perf: Validate cpu early in perf_event_alloc()
[linux-2.6.git] / kernel / seccomp.c
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 #include <linux/compat.h>
12
13 /* #define SECCOMP_DEBUG 1 */
14 #define NR_SECCOMP_MODES 1
15
16 /*
17  * Secure computing mode 1 allows only read/write/exit/sigreturn.
18  * To be fully secure this must be combined with rlimit
19  * to limit the stack allocations too.
20  */
21 static int mode1_syscalls[] = {
22         __NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn,
23         0, /* null terminated */
24 };
25
26 #ifdef CONFIG_COMPAT
27 static int mode1_syscalls_32[] = {
28         __NR_seccomp_read_32, __NR_seccomp_write_32, __NR_seccomp_exit_32, __NR_seccomp_sigreturn_32,
29         0, /* null terminated */
30 };
31 #endif
32
33 void __secure_computing(int this_syscall)
34 {
35         int mode = current->seccomp.mode;
36         int * syscall;
37
38         switch (mode) {
39         case 1:
40                 syscall = mode1_syscalls;
41 #ifdef CONFIG_COMPAT
42                 if (is_compat_task())
43                         syscall = mode1_syscalls_32;
44 #endif
45                 do {
46                         if (*syscall == this_syscall)
47                                 return;
48                 } while (*++syscall);
49                 break;
50         default:
51                 BUG();
52         }
53
54 #ifdef SECCOMP_DEBUG
55         dump_stack();
56 #endif
57         do_exit(SIGKILL);
58 }
59
60 long prctl_get_seccomp(void)
61 {
62         return current->seccomp.mode;
63 }
64
65 long prctl_set_seccomp(unsigned long seccomp_mode)
66 {
67         long ret;
68
69         /* can set it only once to be even more secure */
70         ret = -EPERM;
71         if (unlikely(current->seccomp.mode))
72                 goto out;
73
74         ret = -EINVAL;
75         if (seccomp_mode && seccomp_mode <= NR_SECCOMP_MODES) {
76                 current->seccomp.mode = seccomp_mode;
77                 set_thread_flag(TIF_SECCOMP);
78 #ifdef TIF_NOTSC
79                 disable_TSC();
80 #endif
81                 ret = 0;
82         }
83
84  out:
85         return ret;
86 }