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/*
* 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>
#include <asm/unistd.h>
#ifdef TIF_IA32
#include <asm/ia32_unistd.h>
#endif
/* #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_read, __NR_write, __NR_exit,
/*
* Allow either sigreturn or rt_sigreturn, newer archs
* like x86-64 only defines __NR_rt_sigreturn.
*/
#ifdef __NR_sigreturn
__NR_sigreturn,
#else
__NR_rt_sigreturn,
#endif
0, /* null terminated */
};
#ifdef TIF_IA32
static int mode1_syscalls_32bit[] = {
__NR_ia32_read, __NR_ia32_write, __NR_ia32_exit,
/*
* Allow either sigreturn or rt_sigreturn, newer archs
* like x86-64 only defines __NR_rt_sigreturn.
*/
__NR_ia32_sigreturn,
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_IA32
if (test_thread_flag(TIF_IA32))
syscall = mode1_syscalls_32bit;
#endif
do {
if (*syscall == this_syscall)
return;
} while (*++syscall);
break;
default:
BUG();
}
#ifdef SECCOMP_DEBUG
dump_stack();
#endif
do_exit(SIGKILL);
}
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