ftrace: Update the kconfig for DYNAMIC_FTRACE
[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/audit.h>
10 #include <linux/seccomp.h>
11 #include <linux/sched.h>
12 #include <linux/compat.h>
13
14 /* #define SECCOMP_DEBUG 1 */
15 #define NR_SECCOMP_MODES 1
16
17 /*
18  * Secure computing mode 1 allows only read/write/exit/sigreturn.
19  * To be fully secure this must be combined with rlimit
20  * to limit the stack allocations too.
21  */
22 static int mode1_syscalls[] = {
23         __NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn,
24         0, /* null terminated */
25 };
26
27 #ifdef CONFIG_COMPAT
28 static int mode1_syscalls_32[] = {
29         __NR_seccomp_read_32, __NR_seccomp_write_32, __NR_seccomp_exit_32, __NR_seccomp_sigreturn_32,
30         0, /* null terminated */
31 };
32 #endif
33
34 void __secure_computing(int this_syscall)
35 {
36         int mode = current->seccomp.mode;
37         int * syscall;
38
39         switch (mode) {
40         case 1:
41                 syscall = mode1_syscalls;
42 #ifdef CONFIG_COMPAT
43                 if (is_compat_task())
44                         syscall = mode1_syscalls_32;
45 #endif
46                 do {
47                         if (*syscall == this_syscall)
48                                 return;
49                 } while (*++syscall);
50                 break;
51         default:
52                 BUG();
53         }
54
55 #ifdef SECCOMP_DEBUG
56         dump_stack();
57 #endif
58         audit_seccomp(this_syscall);
59         do_exit(SIGKILL);
60 }
61
62 long prctl_get_seccomp(void)
63 {
64         return current->seccomp.mode;
65 }
66
67 long prctl_set_seccomp(unsigned long seccomp_mode)
68 {
69         long ret;
70
71         /* can set it only once to be even more secure */
72         ret = -EPERM;
73         if (unlikely(current->seccomp.mode))
74                 goto out;
75
76         ret = -EINVAL;
77         if (seccomp_mode && seccomp_mode <= NR_SECCOMP_MODES) {
78                 current->seccomp.mode = seccomp_mode;
79                 set_thread_flag(TIF_SECCOMP);
80 #ifdef TIF_NOTSC
81                 disable_TSC();
82 #endif
83                 ret = 0;
84         }
85
86  out:
87         return ret;
88 }