1 /* $NetBSD: stack_protector.c,v 1.3 2009/01/30 23:21:02 ad Exp $ */ 2 /* $OpenBSD: stack_protector.c,v 1.10 2006/03/31 05:34:44 deraadt Exp $ */ 3 4 /* 5 * Copyright (c) 2002 Hiroaki Etoh, Federico G. Schwindt, and Miodrag Vallat. 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 19 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 20 * DISCLAIMED. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, 21 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 22 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 23 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 25 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 26 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 27 * POSSIBILITY OF SUCH DAMAGE. 28 * 29 */ 30 #include <sys/cdefs.h> 31 __RCSID("$NetBSD: stack_protector.c,v 1.3 2009/01/30 23:21:02 ad Exp $"); 32 33 #ifdef _LIBC 34 #include "namespace.h" 35 #endif 36 #include <sys/param.h> 37 #include <sys/sysctl.h> 38 #include <ssp/ssp.h> 39 #include <signal.h> 40 #include <string.h> 41 #include <unistd.h> 42 #ifdef _LIBC 43 #include <syslog.h> 44 #include "extern.h" 45 #else 46 #define __sysctl sysctl 47 void xprintf(const char *fmt, ...); 48 #include <stdlib.h> 49 #endif 50 51 long __stack_chk_guard[8] = {0, 0, 0, 0, 0, 0, 0, 0}; 52 static void __fail(const char *); 53 void __stack_chk_fail(void); 54 void __chk_fail(void); 55 void __stack_chk_fail_local(void); 56 void __guard_setup(void); 57 58 void 59 __guard_setup(void) 60 { 61 int mib[2]; 62 size_t len; 63 64 if (__stack_chk_guard[0] != 0) 65 return; 66 67 mib[0] = CTL_KERN; 68 mib[1] = KERN_ARND; 69 70 len = sizeof(__stack_chk_guard); 71 if (__sysctl(mib, 2, __stack_chk_guard, &len, NULL, 0) == -1 || 72 len != sizeof(__stack_chk_guard)) { 73 /* If sysctl was unsuccessful, use the "terminator canary". */ 74 ((unsigned char *)(void *)__stack_chk_guard)[0] = 0; 75 ((unsigned char *)(void *)__stack_chk_guard)[1] = 0; 76 ((unsigned char *)(void *)__stack_chk_guard)[2] = '\n'; 77 ((unsigned char *)(void *)__stack_chk_guard)[3] = 255; 78 } 79 } 80 81 /*ARGSUSED*/ 82 static void 83 __fail(const char *msg) 84 { 85 #ifdef _LIBC 86 struct syslog_data sdata = SYSLOG_DATA_INIT; 87 #endif 88 struct sigaction sa; 89 sigset_t mask; 90 91 /* Immediately block all signal handlers from running code */ 92 (void)sigfillset(&mask); 93 (void)sigdelset(&mask, SIGABRT); 94 (void)sigprocmask(SIG_BLOCK, &mask, NULL); 95 96 #ifdef _LIBC 97 /* This may fail on a chroot jail... */ 98 syslog_ss(LOG_CRIT, &sdata, msg); 99 #else 100 xprintf("%s: %s\n", getprogname(), msg); 101 #endif 102 103 (void)memset(&sa, 0, sizeof(sa)); 104 (void)sigemptyset(&sa.sa_mask); 105 sa.sa_flags = 0; 106 sa.sa_handler = SIG_DFL; 107 (void)sigaction(SIGABRT, &sa, NULL); 108 (void)raise(SIGABRT); 109 _exit(127); 110 } 111 112 void 113 __stack_chk_fail(void) 114 { 115 __fail("stack overflow detected; terminated"); 116 } 117 118 void 119 __chk_fail(void) 120 { 121 __fail("buffer overflow detected; terminated"); 122 } 123 124 void 125 __stack_chk_fail_local(void) 126 { 127 __stack_chk_fail(); 128 } 129