Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * linux/kernel/seccomp.c |
| 3 | * |
| 4 | * Copyright 2004-2005 Andrea Arcangeli <andrea@cpushare.com> |
| 5 | * |
| 6 | * This defines a simple but solid secure-computing mode. |
| 7 | */ |
| 8 | |
| 9 | #include <linux/seccomp.h> |
| 10 | #include <linux/sched.h> |
| 11 | |
| 12 | /* #define SECCOMP_DEBUG 1 */ |
| 13 | |
| 14 | /* |
| 15 | * Secure computing mode 1 allows only read/write/exit/sigreturn. |
| 16 | * To be fully secure this must be combined with rlimit |
| 17 | * to limit the stack allocations too. |
| 18 | */ |
| 19 | static int mode1_syscalls[] = { |
| 20 | __NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn, |
| 21 | 0, /* null terminated */ |
| 22 | }; |
| 23 | |
| 24 | #ifdef TIF_32BIT |
| 25 | static int mode1_syscalls_32[] = { |
| 26 | __NR_seccomp_read_32, __NR_seccomp_write_32, __NR_seccomp_exit_32, __NR_seccomp_sigreturn_32, |
| 27 | 0, /* null terminated */ |
| 28 | }; |
| 29 | #endif |
| 30 | |
| 31 | void __secure_computing(int this_syscall) |
| 32 | { |
| 33 | int mode = current->seccomp.mode; |
| 34 | int * syscall; |
| 35 | |
| 36 | switch (mode) { |
| 37 | case 1: |
| 38 | syscall = mode1_syscalls; |
| 39 | #ifdef TIF_32BIT |
| 40 | if (test_thread_flag(TIF_32BIT)) |
| 41 | syscall = mode1_syscalls_32; |
| 42 | #endif |
| 43 | do { |
| 44 | if (*syscall == this_syscall) |
| 45 | return; |
| 46 | } while (*++syscall); |
| 47 | break; |
| 48 | default: |
| 49 | BUG(); |
| 50 | } |
| 51 | |
| 52 | #ifdef SECCOMP_DEBUG |
| 53 | dump_stack(); |
| 54 | #endif |
| 55 | do_exit(SIGKILL); |
| 56 | } |