/* * 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_32BITstatic 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;}