1 /* $OpenBSD: stack_protector.c,v 1.2 2002/12/02 09:02:57 deraadt Exp $ */ 2 3 /* 4 * Copyright (c) 2002 Hiroaki Etoh, Federico G. Schwindt, and Miodrag Vallat. 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 AUTHORS ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 18 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 19 * DISCLAIMED. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, 20 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 21 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 22 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 24 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 25 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 26 * POSSIBILITY OF SUCH DAMAGE. 27 * 28 */ 29 30 #if defined(LIBC_SCCS) && !defined(list) 31 static char rcsid[] = "$OpenBSD: stack_protector.c,v 1.2 2002/12/02 09:02:57 deraadt Exp $"; 32 #endif 33 34 #include <sys/param.h> 35 #include <sys/sysctl.h> 36 #include <syslog.h> 37 38 long __guard[8] = {0, 0, 0, 0, 0, 0, 0, 0}; 39 static void __guard_setup(void) __attribute__ ((constructor)); 40 void __stack_smash_handler(char func[], int damaged __attribute__((unused))); 41 42 static void 43 __guard_setup(void) 44 { 45 int i, mib[2]; 46 size_t len; 47 48 if (__guard[0] != 0) 49 return; 50 51 mib[0] = CTL_KERN; 52 mib[1] = KERN_ARND; 53 54 len = 4; 55 for (i = 0; i < sizeof(__guard) / 4; i++) { 56 if (sysctl(mib, 2, (char *)&((int *)__guard)[i], 57 &len, NULL, 0) == -1) 58 break; 59 } 60 61 if (i < sizeof(__guard) / 4) { 62 /* If sysctl was unsuccessful, use the "terminator canary". */ 63 ((char *)__guard)[0] = 0; ((char*)__guard)[1] = 0; 64 ((char *)__guard)[2] = '\n'; ((char *)__guard)[3] = 255; 65 } 66 } 67 68 void 69 __stack_smash_handler(char func[], int damaged) 70 { 71 struct syslog_data sdata = SYSLOG_DATA_INIT; 72 const char message[] = "stack overflow in function %s"; 73 struct sigaction sa; 74 75 /* this may fail on a chroot jail, though luck */ 76 syslog_r(LOG_CRIT, &sdata, message, func); 77 78 bzero(sa, sizeof(struct sigaction)); 79 sigemptyset(&sa.sa_mask); 80 sa.sa_flags = 0; 81 sa.sa_handler = SIG_DFL; 82 sigaction(SIGABRT, &sa, NULL); 83 84 kill(getpid(), SIGABRT); 85 86 _exit(127); 87 } 88