2 * linux/kernel/seccomp.c
4 * Copyright 2004-2005 Andrea Arcangeli <andrea@cpushare.com>
6 * This defines a simple but solid secure-computing mode.
9 #include <linux/seccomp.h>
10 #include <linux/sched.h>
12 /* #define SECCOMP_DEBUG 1 */
13 #define NR_SECCOMP_MODES 1
16 * Secure computing mode 1 allows only read/write/exit/sigreturn.
17 * To be fully secure this must be combined with rlimit
18 * to limit the stack allocations too.
20 static int mode1_syscalls
[] = {
21 __NR_seccomp_read
, __NR_seccomp_write
, __NR_seccomp_exit
, __NR_seccomp_sigreturn
,
22 0, /* null terminated */
26 static int mode1_syscalls_32
[] = {
27 __NR_seccomp_read_32
, __NR_seccomp_write_32
, __NR_seccomp_exit_32
, __NR_seccomp_sigreturn_32
,
28 0, /* null terminated */
32 void __secure_computing(int this_syscall
)
34 int mode
= current
->seccomp
.mode
;
39 syscall
= mode1_syscalls
;
41 if (test_thread_flag(TIF_32BIT
))
42 syscall
= mode1_syscalls_32
;
45 if (*syscall
== this_syscall
)
59 long prctl_get_seccomp(void)
61 return current
->seccomp
.mode
;
64 long prctl_set_seccomp(unsigned long seccomp_mode
)
68 /* can set it only once to be even more secure */
70 if (unlikely(current
->seccomp
.mode
))
74 if (seccomp_mode
&& seccomp_mode
<= NR_SECCOMP_MODES
) {
75 current
->seccomp
.mode
= seccomp_mode
;
76 set_thread_flag(TIF_SECCOMP
);