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