diff options
Diffstat (limited to 'samples/seccomp/dropper.c')
| -rw-r--r-- | samples/seccomp/dropper.c | 68 |
1 files changed, 68 insertions, 0 deletions
diff --git a/samples/seccomp/dropper.c b/samples/seccomp/dropper.c new file mode 100644 index 000000000000..c69c347c7011 --- /dev/null +++ b/samples/seccomp/dropper.c | |||
| @@ -0,0 +1,68 @@ | |||
| 1 | /* | ||
| 2 | * Naive system call dropper built on seccomp_filter. | ||
| 3 | * | ||
| 4 | * Copyright (c) 2012 The Chromium OS Authors <chromium-os-dev@chromium.org> | ||
| 5 | * Author: Will Drewry <wad@chromium.org> | ||
| 6 | * | ||
| 7 | * The code may be used by anyone for any purpose, | ||
| 8 | * and can serve as a starting point for developing | ||
| 9 | * applications using prctl(PR_SET_SECCOMP, 2, ...). | ||
| 10 | * | ||
| 11 | * When run, returns the specified errno for the specified | ||
| 12 | * system call number against the given architecture. | ||
| 13 | * | ||
| 14 | * Run this one as root as PR_SET_NO_NEW_PRIVS is not called. | ||
| 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 | }; | ||
| 45 | if (prctl(PR_SET_SECCOMP, 2, &prog)) { | ||
| 46 | perror("prctl"); | ||
| 47 | return 1; | ||
| 48 | } | ||
| 49 | return 0; | ||
| 50 | } | ||
| 51 | |||
| 52 | int main(int argc, char **argv) | ||
| 53 | { | ||
| 54 | if (argc < 5) { | ||
| 55 | fprintf(stderr, "Usage:\n" | ||
| 56 | "dropper <syscall_nr> <arch> <errno> <prog> [<args>]\n" | ||
| 57 | "Hint: AUDIT_ARCH_I386: 0x%X\n" | ||
| 58 | " AUDIT_ARCH_X86_64: 0x%X\n" | ||
| 59 | "\n", AUDIT_ARCH_I386, AUDIT_ARCH_X86_64); | ||
| 60 | return 1; | ||
| 61 | } | ||
| 62 | if (install_filter(strtol(argv[1], NULL, 0), strtol(argv[2], NULL, 0), | ||
| 63 | strtol(argv[3], NULL, 0))) | ||
| 64 | return 1; | ||
| 65 | execv(argv[4], &argv[4]); | ||
| 66 | printf("Failed to execv\n"); | ||
| 67 | return 255; | ||
| 68 | } | ||