1 /* $NetBSD: stack_protector.c,v 1.9 2013/08/19 22:14:37 matt 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 1.9 2013/08/19 22:14:37 matt 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 __dead void __stack_chk_fail_local(void);
54 void __guard_setup(void);
55
56 void __section(".text.startup")
__guard_setup(void)57 __guard_setup(void)
58 {
59 #if !defined(__minix)
60 static const int mib[2] = { CTL_KERN, KERN_ARND };
61 size_t len;
62 #endif /* !defined(__minix) */
63
64 if (__stack_chk_guard[0] != 0)
65 return;
66
67 #if !defined(__minix)
68 len = sizeof(__stack_chk_guard);
69 if (__sysctl(mib, (u_int)__arraycount(mib), __stack_chk_guard, &len,
70 NULL, 0) == -1 || len != sizeof(__stack_chk_guard)) {
71 #endif /* !defined(__minix) */
72 /* If sysctl was unsuccessful, use the "terminator canary". */
73 ((unsigned char *)(void *)__stack_chk_guard)[0] = 0;
74 ((unsigned char *)(void *)__stack_chk_guard)[1] = 0;
75 ((unsigned char *)(void *)__stack_chk_guard)[2] = '\n';
76 ((unsigned char *)(void *)__stack_chk_guard)[3] = 255;
77 #if !defined(__minix)
78 }
79 #endif /* !defined(__minix) */
80 }
81
82 /*ARGSUSED*/
83 static void
__fail(const char * msg)84 __fail(const char *msg)
85 {
86 #ifdef _LIBC
87 struct syslog_data sdata = SYSLOG_DATA_INIT;
88 /* MINIX: #endif */
89 struct sigaction sa;
90 sigset_t mask;
91
92 /* Immediately block all signal handlers from running code */
93 (void)sigfillset(&mask);
94 (void)sigdelset(&mask, SIGABRT);
95 (void)sigprocmask(SIG_BLOCK, &mask, NULL);
96
97 /* MINIX: #ifdef _LIBC */
98 /* This may fail on a chroot jail... */
99 syslog_ss(LOG_CRIT, &sdata, "%s", msg);
100 #else
101 xprintf("%s: %s\n", getprogname(), msg);
102 #endif
103
104 #if defined(__minix) && defined(_LIBC)
105 (void)memset(&sa, 0, sizeof(sa));
106 (void)sigemptyset(&sa.sa_mask);
107 sa.sa_flags = 0;
108 sa.sa_handler = SIG_DFL;
109 (void)sigaction(SIGABRT, &sa, NULL);
110 (void)raise(SIGABRT);
111 #endif /* defined(__minix) && defined(_LIBC) */
112 _exit(127);
113 }
114
115 void
__stack_chk_fail(void)116 __stack_chk_fail(void)
117 {
118 __fail("stack overflow detected; terminated");
119 }
120
121 void
__chk_fail(void)122 __chk_fail(void)
123 {
124 __fail("buffer overflow detected; terminated");
125 }
126
127 void
__stack_chk_fail_local(void)128 __stack_chk_fail_local(void)
129 {
130 __stack_chk_fail();
131 }
132