Subversion Repositories or1k_soc_on_altera_embedded_dev_kit

/*

 * 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;

}