forked from luck/tmp_suning_uos_patched
cf99abace7
This follows a suggestion from Chuck Ebbert on how to make seccomp absolutely zerocost in schedule too. The only remaining footprint of seccomp is in terms of the bzImage size that becomes a few bytes (perhaps even a few kbytes) larger, measure it if you care in the embedded. Signed-off-by: Andrea Arcangeli <andrea@cpushare.com> Cc: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
86 lines
1.6 KiB
C
86 lines
1.6 KiB
C
/*
|
|
* linux/kernel/seccomp.c
|
|
*
|
|
* Copyright 2004-2005 Andrea Arcangeli <andrea@cpushare.com>
|
|
*
|
|
* This defines a simple but solid secure-computing mode.
|
|
*/
|
|
|
|
#include <linux/seccomp.h>
|
|
#include <linux/sched.h>
|
|
|
|
/* #define SECCOMP_DEBUG 1 */
|
|
#define NR_SECCOMP_MODES 1
|
|
|
|
/*
|
|
* Secure computing mode 1 allows only read/write/exit/sigreturn.
|
|
* To be fully secure this must be combined with rlimit
|
|
* to limit the stack allocations too.
|
|
*/
|
|
static int mode1_syscalls[] = {
|
|
__NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn,
|
|
0, /* null terminated */
|
|
};
|
|
|
|
#ifdef TIF_32BIT
|
|
static int mode1_syscalls_32[] = {
|
|
__NR_seccomp_read_32, __NR_seccomp_write_32, __NR_seccomp_exit_32, __NR_seccomp_sigreturn_32,
|
|
0, /* null terminated */
|
|
};
|
|
#endif
|
|
|
|
void __secure_computing(int this_syscall)
|
|
{
|
|
int mode = current->seccomp.mode;
|
|
int * syscall;
|
|
|
|
switch (mode) {
|
|
case 1:
|
|
syscall = mode1_syscalls;
|
|
#ifdef TIF_32BIT
|
|
if (test_thread_flag(TIF_32BIT))
|
|
syscall = mode1_syscalls_32;
|
|
#endif
|
|
do {
|
|
if (*syscall == this_syscall)
|
|
return;
|
|
} while (*++syscall);
|
|
break;
|
|
default:
|
|
BUG();
|
|
}
|
|
|
|
#ifdef SECCOMP_DEBUG
|
|
dump_stack();
|
|
#endif
|
|
do_exit(SIGKILL);
|
|
}
|
|
|
|
long prctl_get_seccomp(void)
|
|
{
|
|
return current->seccomp.mode;
|
|
}
|
|
|
|
long prctl_set_seccomp(unsigned long seccomp_mode)
|
|
{
|
|
long ret;
|
|
|
|
/* can set it only once to be even more secure */
|
|
ret = -EPERM;
|
|
if (unlikely(current->seccomp.mode))
|
|
goto out;
|
|
|
|
ret = -EINVAL;
|
|
if (seccomp_mode && seccomp_mode <= NR_SECCOMP_MODES) {
|
|
current->seccomp.mode = seccomp_mode;
|
|
set_thread_flag(TIF_SECCOMP);
|
|
#ifdef TIF_NOTSC
|
|
disable_TSC();
|
|
#endif
|
|
ret = 0;
|
|
}
|
|
|
|
out:
|
|
return ret;
|
|
}
|