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kern_ssp.c revision 1.5 
      1 /*	$NetBSD: kern_ssp.c,v 1.5 2010/02/01 16:14:58 njoly 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 1.5 2010/02/01 16:14:58 njoly Exp $");
     31 
     32 #include <sys/param.h>
     33 #include <sys/systm.h>
     34 #include <sys/intr.h>
     35 
     36 #if defined(__SSP__) || defined(__SSP_ALL__)
     37 long __stack_chk_guard[8] = {0, 0, 0, 0, 0, 0, 0, 0};
     38 void __stack_chk_fail(void);
     39 
     40 void
     41 __stack_chk_fail(void)
     42 {
     43 	panic("stack overflow detected; terminated");
     44 }
     45 
     46 void
     47 ssp_init(void)
     48 {
     49 	int s;
     50 
     51 	aprint_debug("Initializing SSP: ");
     52 	/*
     53 	 * We initialize ssp here carefully:
     54 	 *	1. after we got some entropy
     55 	 *	2. without calling a function
     56 	 */
     57 	size_t i;
     58 	long guard[__arraycount(__stack_chk_guard)];
     59 
     60 	arc4randbytes(guard, sizeof(guard));
     61 	s = splhigh();
     62 	for (i = 0; i < __arraycount(guard); i++)
     63 		__stack_chk_guard[i] = guard[i];
     64 	splx(s);
     65 	for (i = 0; i < __arraycount(guard); i++)
     66 		aprint_debug("%lx ", guard[i]);
     67 	aprint_debug("\n");
     68 }
     69 #else
     70 void
     71 ssp_init(void)
     72 {
     73 }
     74 #endif
     75