Home | History | Annotate | Line # | Download | only in kern 
      1 /*	$NetBSD: kern_ssp.c,v 1.7 2016/12/06 02:55:42 christos Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2008 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     17  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     18  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     19  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     20  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     21  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     22  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     23  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     24  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     25  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     26  * POSSIBILITY OF SUCH DAMAGE.
     27  */
     28 
     29 #include <sys/cdefs.h>
     30 __KERNEL_RCSID(0, "$NetBSD: kern_ssp.c,v 1.7 2016/12/06 02:55:42 christos Exp $");
     31 
     32 #include <sys/param.h>
     33 #include <sys/systm.h>
     34 #include <sys/intr.h>
     35 #include <sys/cprng.h>
     36 
     37 #if defined(__SSP__) || defined(__SSP_ALL__)
     38 # ifdef _RUMPKERNEL
     39 __weak_alias(__stack_chk_guard, stack_chk_guard)
     40 __weak_alias(__stack_chk_fail, stack_chk_fail)
     41 # define SSP_STATIC static __used
     42 # else
     43 # define stack_chk_guard __stack_chk_guard
     44 # define stack_chk_fail __stack_chk_fail
     45 # define SSP_STATIC
     46 #endif
     47 
     48 SSP_STATIC long stack_chk_guard[8] = {0, 0, 0, 0, 0, 0, 0, 0,};
     49 SSP_STATIC void stack_chk_fail(void);
     50 
     51 SSP_STATIC void
     52 stack_chk_fail(void)
     53 {
     54 	panic("stack overflow detected; terminated");
     55 }
     56 
     57 void
     58 ssp_init(void)
     59 {
     60 	int s;
     61 
     62 	aprint_debug("Initializing SSP: ");
     63 	/*
     64 	 * We initialize ssp here carefully:
     65 	 *	1. after we got some entropy
     66 	 *	2. without calling a function
     67 	 */
     68 	size_t i;
     69 	long guard[__arraycount(stack_chk_guard)];
     70 
     71 	cprng_fast(guard, sizeof(guard));
     72 	s = splhigh();
     73 	for (i = 0; i < __arraycount(guard); i++)
     74 		stack_chk_guard[i] = guard[i];
     75 	splx(s);
     76 	for (i = 0; i < __arraycount(guard); i++)
     77 		aprint_debug("%lx ", guard[i]);
     78 	aprint_debug("\n");
     79 }
     80 #else
     81 void
     82 ssp_init(void)
     83 {
     84 }
     85 #endif
     86