1 /* $NetBSD: stack_protector.c,v 1.5 2010/12/07 20:10:53 joerg 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 1.5 2010/12/07 20:10:53 joerg 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 *) __attribute__((__noreturn__)); 53 void __stack_chk_fail_local(void); 54 void __guard_setup(void); 55 56 void 57 __guard_setup(void) 58 { 59 #ifndef __minix 60 int mib[2]; 61 size_t len; 62 #endif 63 64 if (__stack_chk_guard[0] != 0) 65 return; 66 67 #ifndef __minix 68 mib[0] = CTL_KERN; 69 mib[1] = KERN_ARND; 70 71 len = sizeof(__stack_chk_guard); 72 if (__sysctl(mib, 2, __stack_chk_guard, &len, NULL, 0) == -1 || 73 len != sizeof(__stack_chk_guard)) { 74 #endif 75 /* If sysctl was unsuccessful, use the "terminator canary". */ 76 ((unsigned char *)(void *)__stack_chk_guard)[0] = 0; 77 ((unsigned char *)(void *)__stack_chk_guard)[1] = 0; 78 ((unsigned char *)(void *)__stack_chk_guard)[2] = '\n'; 79 ((unsigned char *)(void *)__stack_chk_guard)[3] = 255; 80 #ifndef __minix 81 } 82 #endif 83 } 84 85 /*ARGSUSED*/ 86 static void 87 __fail(const char *msg) 88 { 89 #ifdef _LIBC 90 struct syslog_data sdata = SYSLOG_DATA_INIT; 91 #endif 92 struct sigaction sa; 93 sigset_t mask; 94 95 /* Immediately block all signal handlers from running code */ 96 (void)sigfillset(&mask); 97 (void)sigdelset(&mask, SIGABRT); 98 (void)sigprocmask(SIG_BLOCK, &mask, NULL); 99 100 #ifdef _LIBC 101 /* This may fail on a chroot jail... */ 102 syslog_ss(LOG_CRIT, &sdata, "%s", msg); 103 #else 104 xprintf("%s: %s\n", getprogname(), msg); 105 #endif 106 107 (void)memset(&sa, 0, sizeof(sa)); 108 (void)sigemptyset(&sa.sa_mask); 109 sa.sa_flags = 0; 110 sa.sa_handler = SIG_DFL; 111 (void)sigaction(SIGABRT, &sa, NULL); 112 (void)raise(SIGABRT); 113 _exit(127); 114 } 115 116 void 117 __stack_chk_fail(void) 118 { 119 __fail("stack overflow detected; terminated"); 120 } 121 122 void 123 __chk_fail(void) 124 { 125 __fail("buffer overflow detected; terminated"); 126 } 127 128 void 129 __stack_chk_fail_local(void) 130 { 131 __stack_chk_fail(); 132 } 133