// https://syzkaller.appspot.com/bug?id=039bf53503778d3401b657cb99a68e5803f69eae // autogenerated by syzkaller (https://github.com/google/syzkaller) #define _GNU_SOURCE #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifndef __NR_landlock_add_rule #define __NR_landlock_add_rule 445 #endif #ifndef __NR_landlock_create_ruleset #define __NR_landlock_create_ruleset 444 #endif static bool write_file(const char* file, const char* what, ...) { char buf[1024]; va_list args; va_start(args, what); vsnprintf(buf, sizeof(buf), what, args); va_end(args); buf[sizeof(buf) - 1] = 0; int len = strlen(buf); int fd = open(file, O_WRONLY | O_CLOEXEC); if (fd == -1) return false; if (write(fd, buf, len) != len) { int err = errno; close(fd); errno = err; return false; } close(fd); return true; } static int runcmdline(char* cmdline) { int ret = system(cmdline); if (ret) { } return ret; } static void setup_gadgetfs(); static void setup_binderfs(); static void setup_fusectl(); static void sandbox_common_mount_tmpfs(void) { write_file("/proc/sys/fs/mount-max", "100000"); if (mkdir("./syz-tmp", 0777)) exit(1); if (mount("", "./syz-tmp", "tmpfs", 0, NULL)) exit(1); if (mkdir("./syz-tmp/newroot", 0777)) exit(1); if (mkdir("./syz-tmp/newroot/dev", 0700)) exit(1); unsigned bind_mount_flags = MS_BIND | MS_REC | MS_PRIVATE; if (mount("/dev", "./syz-tmp/newroot/dev", NULL, bind_mount_flags, NULL)) exit(1); if (mkdir("./syz-tmp/newroot/proc", 0700)) exit(1); if (mount("syz-proc", "./syz-tmp/newroot/proc", "proc", 0, NULL)) exit(1); if (mkdir("./syz-tmp/newroot/selinux", 0700)) exit(1); const char* selinux_path = "./syz-tmp/newroot/selinux"; if (mount("/selinux", selinux_path, NULL, bind_mount_flags, NULL)) { if (errno != ENOENT) exit(1); if (mount("/sys/fs/selinux", selinux_path, NULL, bind_mount_flags, NULL) && errno != ENOENT) exit(1); } if (mkdir("./syz-tmp/newroot/sys", 0700)) exit(1); if (mount("/sys", "./syz-tmp/newroot/sys", 0, bind_mount_flags, NULL)) exit(1); if (mount("/sys/kernel/debug", "./syz-tmp/newroot/sys/kernel/debug", NULL, bind_mount_flags, NULL) && errno != ENOENT) exit(1); if (mount("/sys/fs/smackfs", "./syz-tmp/newroot/sys/fs/smackfs", NULL, bind_mount_flags, NULL) && errno != ENOENT) exit(1); if (mount("/proc/sys/fs/binfmt_misc", "./syz-tmp/newroot/proc/sys/fs/binfmt_misc", NULL, bind_mount_flags, NULL) && errno != ENOENT) exit(1); if (mkdir("./syz-tmp/newroot/syz-inputs", 0700)) exit(1); if (mount("/syz-inputs", "./syz-tmp/newroot/syz-inputs", NULL, bind_mount_flags | MS_RDONLY, NULL) && errno != ENOENT) exit(1); if (mkdir("./syz-tmp/pivot", 0777)) exit(1); if (syscall(SYS_pivot_root, "./syz-tmp", "./syz-tmp/pivot")) { if (chdir("./syz-tmp")) exit(1); } else { if (chdir("/")) exit(1); if (umount2("./pivot", MNT_DETACH)) exit(1); } if (chroot("./newroot")) exit(1); if (chdir("/")) exit(1); setup_gadgetfs(); setup_binderfs(); setup_fusectl(); } static void setup_gadgetfs() { if (mkdir("/dev/gadgetfs", 0777)) { } if (mount("gadgetfs", "/dev/gadgetfs", "gadgetfs", 0, NULL)) { } } static void setup_fusectl() { if (mount(0, "/sys/fs/fuse/connections", "fusectl", 0, 0)) { } } static void setup_binderfs() { if (mkdir("/dev/binderfs", 0777)) { } if (mount("binder", "/dev/binderfs", "binder", 0, NULL)) { } if (symlink("/dev/binderfs", "./binderfs")) { } } static void loop(); static void sandbox_common() { prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0); if (getppid() == 1) exit(1); struct rlimit rlim; rlim.rlim_cur = rlim.rlim_max = (200 << 20); setrlimit(RLIMIT_AS, &rlim); rlim.rlim_cur = rlim.rlim_max = 32 << 20; setrlimit(RLIMIT_MEMLOCK, &rlim); rlim.rlim_cur = rlim.rlim_max = 136 << 20; setrlimit(RLIMIT_FSIZE, &rlim); rlim.rlim_cur = rlim.rlim_max = 1 << 20; setrlimit(RLIMIT_STACK, &rlim); rlim.rlim_cur = rlim.rlim_max = 128 << 20; setrlimit(RLIMIT_CORE, &rlim); rlim.rlim_cur = rlim.rlim_max = 256; setrlimit(RLIMIT_NOFILE, &rlim); if (unshare(CLONE_NEWNS)) { } if (mount(NULL, "/", NULL, MS_REC | MS_PRIVATE, NULL)) { } if (unshare(CLONE_NEWIPC)) { } if (unshare(0x02000000)) { } if (unshare(CLONE_NEWUTS)) { } if (unshare(CLONE_SYSVSEM)) { } typedef struct { const char* name; const char* value; } sysctl_t; static const sysctl_t sysctls[] = { {"/proc/sys/kernel/shmmax", "16777216"}, {"/proc/sys/kernel/shmall", "536870912"}, {"/proc/sys/kernel/shmmni", "1024"}, {"/proc/sys/kernel/msgmax", "8192"}, {"/proc/sys/kernel/msgmni", "1024"}, {"/proc/sys/kernel/msgmnb", "1024"}, {"/proc/sys/kernel/sem", "1024 1048576 500 1024"}, }; unsigned i; for (i = 0; i < sizeof(sysctls) / sizeof(sysctls[0]); i++) write_file(sysctls[i].name, sysctls[i].value); } static int wait_for_loop(int pid) { if (pid < 0) exit(1); int status = 0; while (waitpid(-1, &status, __WALL) != pid) { } return WEXITSTATUS(status); } static void drop_caps(void) { struct __user_cap_header_struct cap_hdr = {}; struct __user_cap_data_struct cap_data[2] = {}; cap_hdr.version = _LINUX_CAPABILITY_VERSION_3; cap_hdr.pid = getpid(); if (syscall(SYS_capget, &cap_hdr, &cap_data)) exit(1); const int drop = (1 << CAP_SYS_PTRACE) | (1 << CAP_SYS_NICE); cap_data[0].effective &= ~drop; cap_data[0].permitted &= ~drop; cap_data[0].inheritable &= ~drop; if (syscall(SYS_capset, &cap_hdr, &cap_data)) exit(1); } static int do_sandbox_none(void) { if (unshare(CLONE_NEWPID)) { } int pid = fork(); if (pid != 0) return wait_for_loop(pid); sandbox_common(); drop_caps(); if (unshare(CLONE_NEWNET)) { } write_file("/proc/sys/net/ipv4/ping_group_range", "0 65535"); sandbox_common_mount_tmpfs(); loop(); exit(1); } #define SWAP_FILE "./swap-file" #define SWAP_FILE_SIZE (128 * 1000 * 1000) static const char* setup_swap() { swapoff(SWAP_FILE); unlink(SWAP_FILE); int fd = open(SWAP_FILE, O_CREAT | O_WRONLY | O_CLOEXEC, 0600); if (fd == -1) return "swap file open failed"; fallocate(fd, FALLOC_FL_ZERO_RANGE, 0, SWAP_FILE_SIZE); close(fd); char cmdline[64]; sprintf(cmdline, "mkswap %s", SWAP_FILE); if (runcmdline(cmdline)) return "mkswap failed"; if (swapon(SWAP_FILE, SWAP_FLAG_PREFER) == 1) return "swapon failed"; return NULL; } uint64_t r[2] = {0xffffffffffffffff, 0xffffffffffffffff}; void loop(void) { intptr_t res = 0; if (write(1, "executing program\n", sizeof("executing program\n") - 1)) { } // mkdirat arguments: [ // fd: fd_dir (resource) // path: ptr[in, buffer] { // buffer: {2e 2f 66 69 6c 65 30 00} (length 0x8) // } // mode: open_mode = 0x1c0 (8 bytes) // ] memcpy((void*)0x200000000040, "./file0\000", 8); syscall(__NR_mkdirat, /*fd=*/0xffffff9c, /*path=*/0x200000000040ul, /*mode=S_IXUSR|S_IWUSR|S_IRUSR*/ 0x1c0ul); // mount$tmpfs arguments: [ // src: const = 0x0 (8 bytes) // dst: ptr[in, buffer] { // buffer: {2e 2f 66 69 6c 65 30 00} (length 0x8) // } // type: ptr[in, buffer] { // buffer: {74 6d 70 66 73 00} (length 0x6) // } // flags: mount_flags = 0x0 (8 bytes) // opts: nil // ] memcpy((void*)0x200000000080, "./file0\000", 8); memcpy((void*)0x2000000000c0, "tmpfs\000", 6); syscall(__NR_mount, /*src=*/0ul, /*dst=*/0x200000000080ul, /*type=*/0x2000000000c0ul, /*flags=*/0ul, /*opts=*/0ul); // landlock_create_ruleset arguments: [ // attr: ptr[in, landlock_ruleset_attr] { // landlock_ruleset_attr { // handled_access_fs: landlock_access_fs_flags = 0x100 (8 bytes) // handled_access_net: landlock_access_net_flags = 0x0 (8 bytes) // scoped: landlock_scope_flags = 0x0 (8 bytes) // } // } // size: bytesize = 0x18 (8 bytes) // flags: landlock_create_ruleset_flags = 0x0 (8 bytes) // ] // returns fd_ruleset *(uint64_t*)0x200000000180 = 0x100; *(uint64_t*)0x200000000188 = 0; *(uint64_t*)0x200000000190 = 0; res = syscall(__NR_landlock_create_ruleset, /*attr=*/0x200000000180ul, /*size=*/0x18ul, /*flags=*/0ul); if (res != -1) r[0] = res; // openat$dir arguments: [ // fd: const = 0xffffffffffffff9c (8 bytes) // file: ptr[in, buffer] { // buffer: {2e 2f 66 69 6c 65 30 00} (length 0x8) // } // flags: open_flags = 0x200000 (4 bytes) // mode: open_mode = 0x0 (2 bytes) // ] // returns fd_dir memcpy((void*)0x2000000001c0, "./file0\000", 8); res = syscall(__NR_openat, /*fd=*/0xffffffffffffff9cul, /*file=*/0x2000000001c0ul, /*flags=O_PATH*/ 0x200000, /*mode=*/0); if (res != -1) r[1] = res; // landlock_add_rule$LANDLOCK_RULE_PATH_BENEATH arguments: [ // ruleset_fd: fd_ruleset (resource) // rule_type: const = 0x1 (8 bytes) // rule_attr: ptr[in, landlock_path_beneath_attr] { // landlock_path_beneath_attr { // allowed_access: landlock_access_fs_flags = 0x100 (8 bytes) // parent_fd: fd (resource) // } // } // flags: const = 0x0 (8 bytes) // ] *(uint64_t*)0x200000000200 = 0x100; *(uint32_t*)0x200000000208 = r[1]; syscall(__NR_landlock_add_rule, /*ruleset_fd=*/r[0], /*rule_type=*/1ul, /*rule_attr=*/0x200000000200ul, /*flags=*/0ul); // close arguments: [ // fd: fd (resource) // ] syscall(__NR_close, /*fd=*/r[1]); // umount2 arguments: [ // path: ptr[in, buffer] { // buffer: {2e 2f 66 69 6c 65 30 00} (length 0x8) // } // flags: umount_flags = 0x0 (8 bytes) // ] memcpy((void*)0x2000000002c0, "./file0\000", 8); syscall(__NR_umount2, /*path=*/0x2000000002c0ul, /*flags=*/0ul); } 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; if ((reason = setup_swap())) printf("the reproducer may not work as expected: swap setup failed: %s\n", reason); do_sandbox_none(); return 0; }