Dmitry V. Levin | 485f8fb | 2015-03-19 00:40:49 +0000 | [diff] [blame] | 1 | #ifdef HAVE_CONFIG_H |
| 2 | # include "config.h" |
| 3 | #endif |
| 4 | |
| 5 | #include <stddef.h> |
| 6 | #include <unistd.h> |
| 7 | #include <stdio.h> |
| 8 | #include <errno.h> |
| 9 | #include <sys/syscall.h> |
| 10 | |
| 11 | #ifdef HAVE_PRCTL |
| 12 | # include <sys/prctl.h> |
| 13 | #endif |
| 14 | #ifdef HAVE_LINUX_SECCOMP_H |
| 15 | # include <linux/seccomp.h> |
| 16 | #endif |
| 17 | #ifdef HAVE_LINUX_FILTER_H |
| 18 | # include <linux/filter.h> |
| 19 | #endif |
| 20 | |
| 21 | #if defined HAVE_PRCTL \ |
| 22 | && defined PR_SET_NO_NEW_PRIVS \ |
| 23 | && defined PR_SET_SECCOMP \ |
| 24 | && defined SECCOMP_MODE_FILTER \ |
| 25 | && defined SECCOMP_RET_ERRNO \ |
| 26 | && defined BPF_JUMP \ |
| 27 | && defined BPF_STMT |
| 28 | |
| 29 | #define SOCK_FILTER_ALLOW_SYSCALL(nr) \ |
| 30 | BPF_JUMP(BPF_JMP | BPF_K | BPF_JEQ, __NR_ ## nr, 0, 1), \ |
| 31 | BPF_STMT(BPF_RET | BPF_K, SECCOMP_RET_ALLOW) |
| 32 | |
| 33 | #define SOCK_FILTER_DENY_SYSCALL(nr, err) \ |
| 34 | BPF_JUMP(BPF_JMP | BPF_K | BPF_JEQ, __NR_ ## nr, 0, 1), \ |
| 35 | BPF_STMT(BPF_RET | BPF_K, SECCOMP_RET_ERRNO | (SECCOMP_RET_DATA & (err))) |
| 36 | |
| 37 | #define SOCK_FILTER_KILL_PROCESS \ |
| 38 | BPF_STMT(BPF_RET | BPF_K, SECCOMP_RET_KILL) |
| 39 | |
| 40 | #define PRINT_ALLOW_SYSCALL(nr) \ |
| 41 | printf("BPF_JUMP(BPF_JMP | BPF_K | BPF_JEQ, %#x, 0, 0x1), " \ |
| 42 | "BPF_STMT(BPF_RET | BPF_K, SECCOMP_RET_ALLOW), ", \ |
| 43 | __NR_ ## nr) |
| 44 | |
| 45 | #define PRINT_DENY_SYSCALL(nr, err) \ |
| 46 | printf("BPF_JUMP(BPF_JMP | BPF_K | BPF_JEQ, %#x, 0, 0x1), " \ |
| 47 | "BPF_STMT(BPF_RET | BPF_K, SECCOMP_RET_ERRNO | %#x), ", \ |
| 48 | __NR_ ## nr, err) |
| 49 | |
| 50 | static const struct sock_filter filter[] = { |
| 51 | /* load syscall number */ |
| 52 | BPF_STMT(BPF_LD | BPF_W | BPF_ABS, offsetof(struct seccomp_data, nr)), |
| 53 | |
| 54 | /* allow syscalls */ |
| 55 | SOCK_FILTER_ALLOW_SYSCALL(close), |
| 56 | SOCK_FILTER_ALLOW_SYSCALL(exit), |
| 57 | SOCK_FILTER_ALLOW_SYSCALL(exit_group), |
| 58 | |
| 59 | /* deny syscalls */ |
| 60 | SOCK_FILTER_DENY_SYSCALL(sync, EBUSY), |
| 61 | SOCK_FILTER_DENY_SYSCALL(setsid, EPERM), |
| 62 | |
| 63 | /* kill process */ |
| 64 | SOCK_FILTER_KILL_PROCESS |
| 65 | }; |
| 66 | |
| 67 | static const struct sock_fprog prog = { |
| 68 | .len = sizeof(filter) / sizeof(filter[0]), |
| 69 | .filter = (struct sock_filter *) filter, |
| 70 | }; |
| 71 | |
| 72 | int |
| 73 | main(void) |
| 74 | { |
| 75 | int fds[2]; |
| 76 | |
| 77 | puts("prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) = 0"); |
| 78 | |
| 79 | printf("prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, ["); |
| 80 | |
| 81 | printf("BPF_STMT(BPF_LD | BPF_W | BPF_ABS, %#x), ", |
| 82 | (unsigned) offsetof(struct seccomp_data, nr)); |
| 83 | |
| 84 | PRINT_ALLOW_SYSCALL(close); |
| 85 | PRINT_ALLOW_SYSCALL(exit); |
| 86 | PRINT_ALLOW_SYSCALL(exit_group); |
| 87 | |
| 88 | PRINT_DENY_SYSCALL(sync, EBUSY), |
| 89 | PRINT_DENY_SYSCALL(setsid, EPERM), |
| 90 | |
| 91 | printf("BPF_STMT(BPF_RET | BPF_K, SECCOMP_RET_KILL)"); |
| 92 | |
| 93 | puts("]) = 0"); |
| 94 | puts("+++ exited with 0 +++"); |
| 95 | |
| 96 | fflush(stdout); |
| 97 | close(0); |
| 98 | close(1); |
| 99 | |
| 100 | if (pipe(fds) || |
| 101 | prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) || |
| 102 | prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog) || |
| 103 | close(0) || close(1)) |
| 104 | _exit(77); |
| 105 | |
| 106 | _exit(0); |
| 107 | } |
| 108 | |
| 109 | #else |
| 110 | |
| 111 | int main(void) { return 77; } |
| 112 | |
| 113 | #endif |