1 /* $NetBSD: stack_protector.c,v 1.4 2006/11/22 17:23:25 christos Exp $ */
2 /* $OpenBSD: stack_protector.c,v 1.10 2006/03/31 05:34:44 deraadt Exp $ */
4 * Copyright (c) 2002 Hiroaki Etoh, Federico G. Schwindt, and Miodrag Vallat.
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
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.
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.
30 #include <sys/cdefs.h>
31 __FBSDID("$FreeBSD$");
33 #include <sys/param.h>
34 #include <sys/sysctl.h>
35 #include <sys/types.h>
41 extern int __sysctl(int *name, u_int namelen, void *oldp, size_t *oldlenp,
42 void *newp, size_t newlen);
44 long __stack_chk_guard[8] = {0, 0, 0, 0, 0, 0, 0, 0};
45 static void __guard_setup(void) __attribute__((__constructor__, __used__));
46 static void __fail(const char *);
47 void __stack_chk_fail(void);
48 void __chk_fail(void);
57 if (__stack_chk_guard[0] != 0)
63 len = sizeof(__stack_chk_guard);
64 if (__sysctl(mib, 2, __stack_chk_guard, &len, NULL, 0) == -1 ||
65 len != sizeof(__stack_chk_guard)) {
66 /* If sysctl was unsuccessful, use the "terminator canary". */
67 ((unsigned char *)(void *)__stack_chk_guard)[0] = 0;
68 ((unsigned char *)(void *)__stack_chk_guard)[1] = 0;
69 ((unsigned char *)(void *)__stack_chk_guard)[2] = '\n';
70 ((unsigned char *)(void *)__stack_chk_guard)[3] = 255;
76 __fail(const char *msg)
81 /* Immediately block all signal handlers from running code */
82 (void)sigfillset(&mask);
83 (void)sigdelset(&mask, SIGABRT);
84 (void)sigprocmask(SIG_BLOCK, &mask, NULL);
86 /* This may fail on a chroot jail... */
87 syslog(LOG_CRIT, msg);
89 (void)memset(&sa, 0, sizeof(sa));
90 (void)sigemptyset(&sa.sa_mask);
92 sa.sa_handler = SIG_DFL;
93 (void)sigaction(SIGABRT, &sa, NULL);
94 (void)kill(getpid(), SIGABRT);
99 __stack_chk_fail(void)
101 __fail("stack overflow detected; terminated");
107 __fail("buffer overflow detected; terminated");
111 __weak_reference(__stack_chk_fail, __stack_chk_fail_local);