sys/kern/kern_ssp.c

   1 /*      $NetBSD: kern_ssp.c,v 1.2 2009/02/26 05:50:54 kenh 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 1.2 2009/02/26 05:50:54 kenh 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 #ifdef DIAGNOSTIC
  52         printf("Initializing SSP: ");
  53 #endif
  54         /*
  55          * We initialize ssp here carefully:
  56          *      1. after we got some entropy
  57          *      2. without calling a function
  58          */
  59         size_t i;
  60         long guard[__arraycount(__stack_chk_guard)];
  61
  62         arc4randbytes(guard, sizeof(guard));
  63         s = splhigh();
  64         for (i = 0; i < __arraycount(guard); i++)
  65                 __stack_chk_guard[i] = guard[i];
  66         splx(s);
  67 #ifdef DIAGNOSTIC
  68         for (i = 0; i < __arraycount(guard); i++)
  69                 printf("%lx ", guard[i]);
  70         printf("\n");
  71 #endif
  72 }
  73 #else
  74 void
  75 ssp_init(void)
  76 {
  77 }
  78 #endif