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/*
* linux/kernel/seccomp.c
*
* Copyright 2004-2005 Andrea Arcangeli <andrea@cpushare.com>
* Copyright (C) 2011 The Chromium OS Authors <chromium-os-dev@chromium.org>
*
* This defines a simple but solid secure-computing mode.
*/
#include <linux/seccomp.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/compat.h>
#include <linux/unistd.h>
#include <linux/ftrace_event.h>
#define SECCOMP_MAX_FILTER_LENGTH MAX_FILTER_STR_VAL
/* #define SECCOMP_DEBUG 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 CONFIG_COMPAT
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 * syscall;
switch (current->seccomp.mode) {
case 1:
syscall = mode1_syscalls;
#ifdef CONFIG_COMPAT
if (is_compat_task())
syscall = mode1_syscalls_32;
#endif
do {
if (*syscall == this_syscall)
return;
} while (*++syscall);
break;
#ifdef CONFIG_SECCOMP_FILTER
case 13:
if (this_syscall >= NR_syscalls || this_syscall < 0)
break;
if (!seccomp_test_filters(this_syscall))
return;
seccomp_filter_log_failure(this_syscall);
break;
#endif
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 = 0;
switch (seccomp_mode) {
case 1:
#ifdef TIF_NOTSC
disable_TSC();
#endif
#ifdef CONFIG_SECCOMP_FILTER
case 13:
#endif
current->seccomp.mode = seccomp_mode;
set_thread_flag(TIF_SECCOMP);
break;
default:
ret = -EINVAL;
}
out:
return ret;
}
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