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kern_ssp.c revision 1.1 
      1 /*	$NetBSD: kern_ssp.c,v 1.1 2009/02/12 18:24:18 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 1.1 2009/02/12 18:24:18 christos Exp $");
     31 
     32 #include <sys/systm.h>
     33 #include <sys/intr.h>
     34 
     35 #if defined(__SSP__) || defined(__SSP_ALL__)
     36 long __stack_chk_guard[8] = {0, 0, 0, 0, 0, 0, 0, 0};
     37 void __stack_chk_fail(void);
     38 
     39 void
     40 __stack_chk_fail(void)
     41 {
     42 	panic("stack overflow detected; terminated");
     43 }
     44 
     45 void
     46 ssp_init(void)
     47 {
     48 	int s;
     49 
     50 #ifdef DIAGNOSTIC
     51 	printf("Initializing SSP:");
     52 #endif
     53 	/*
     54 	 * We initialize ssp here carefully:
     55 	 *	1. after we got some entropy
     56 	 *	2. without calling a function
     57 	 */
     58 	size_t i;
     59 	long guard[__arraycount(__stack_chk_guard)];
     60 
     61 	arc4randbytes(guard, sizeof(guard));
     62 	s = splhigh();
     63 	for (i = 0; i < __arraycount(guard); i++)
     64 		__stack_chk_guard[i] = guard[i];
     65 	splx(s);
     66 #ifdef DIAGNOSTIC
     67 	for (i = 0; i < __arraycount(guard); i++)
     68 		printf("%lx ", guard[i]);
     69 	printf("\n");
     70 #endif
     71 }
     72 #else
     73 void
     74 ssp_init(void)
     75 {
     76 }
     77 #endif
     78