projects / thirdparty / kernel / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
| 8ac270d1 WD |
2 | /* |
| 3 | * Naive system call dropper built on seccomp_filter. | |
| 4 | * | |
| 5 | * Copyright (c) 2012 The Chromium OS Authors <chromium-os-dev@chromium.org> | |
| 6 | * Author: Will Drewry <wad@chromium.org> | |
| 7 | * | |
| 8 | * The code may be used by anyone for any purpose, | |
| 9 | * and can serve as a starting point for developing | |
| 10 | * applications using prctl(PR_SET_SECCOMP, 2, ...). | |
| 11 | * | |
| 12 | * When run, returns the specified errno for the specified | |
| 13 | * system call number against the given architecture. | |
| 14 | * | |
| 8ac270d1 WD |
15 | */ |
| 16 | ||
| 17 | #include <errno.h> | |
| 18 | #include <linux/audit.h> | |
| 19 | #include <linux/filter.h> | |
| 20 | #include <linux/seccomp.h> | |
| 21 | #include <linux/unistd.h> | |
| 22 | #include <stdio.h> | |
| 23 | #include <stddef.h> | |
| 24 | #include <stdlib.h> | |
| 25 | #include <sys/prctl.h> | |
| 26 | #include <unistd.h> | |
| 27 | ||
| 28 | static int install_filter(int nr, int arch, int error) | |
| 29 | { | |
| 30 | struct sock_filter filter[] = { | |
| 31 | BPF_STMT(BPF_LD+BPF_W+BPF_ABS, | |
| 32 | (offsetof(struct seccomp_data, arch))), | |
| 33 | BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, arch, 0, 3), | |
| 34 | BPF_STMT(BPF_LD+BPF_W+BPF_ABS, | |
| 35 | (offsetof(struct seccomp_data, nr))), | |
| 36 | BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, nr, 0, 1), | |
| 37 | BPF_STMT(BPF_RET+BPF_K, | |
| 38 | SECCOMP_RET_ERRNO|(error & SECCOMP_RET_DATA)), | |
| 39 | BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_ALLOW), | |
| 40 | }; | |
| 41 | struct sock_fprog prog = { | |
| 42 | .len = (unsigned short)(sizeof(filter)/sizeof(filter[0])), | |
| 43 | .filter = filter, | |
| 44 | }; | |
| 1ff12050 RZ |
45 | if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)) { |
| 46 | perror("prctl(NO_NEW_PRIVS)"); | |
| 47 | return 1; | |
| 48 | } | |
| 8ac270d1 | 49 | if (prctl(PR_SET_SECCOMP, 2, &prog)) { |
| 1ff12050 | 50 | perror("prctl(PR_SET_SECCOMP)"); |
| 8ac270d1 WD |
51 | return 1; |
| 52 | } | |
| 53 | return 0; | |
| 54 | } | |
| 55 | ||
| 56 | int main(int argc, char **argv) | |
| 57 | { | |
| 58 | if (argc < 5) { | |
| 59 | fprintf(stderr, "Usage:\n" | |
| 60 | "dropper <syscall_nr> <arch> <errno> <prog> [<args>]\n" | |
| 61 | "Hint: AUDIT_ARCH_I386: 0x%X\n" | |
| 62 | " AUDIT_ARCH_X86_64: 0x%X\n" | |
| 63 | "\n", AUDIT_ARCH_I386, AUDIT_ARCH_X86_64); | |
| 64 | return 1; | |
| 65 | } | |
| 66 | if (install_filter(strtol(argv[1], NULL, 0), strtol(argv[2], NULL, 0), | |
| 67 | strtol(argv[3], NULL, 0))) | |
| 68 | return 1; | |
| 69 | execv(argv[4], &argv[4]); | |
| 70 | printf("Failed to execv\n"); | |
| 71 | return 255; | |
| 72 | } |