1 /* $NetBSD: stack_protector.c,v 1.10 2025/05/02 23:04:56 riastradh 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 1.10 2025/05/02 23:04:56 riastradh 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 void xprintf(const char *fmt, ...);
47 #include <stdlib.h>
48 #endif
49
50 #include "../include/__sysctl.h"
51
52 long __stack_chk_guard[8] = {0, 0, 0, 0, 0, 0, 0, 0};
53 static void __fail(const char *) __attribute__((__noreturn__));
54 __dead void __stack_chk_fail_local(void);
55 void __guard_setup(void);
56
57 void __section(".text.startup")
__guard_setup(void)58 __guard_setup(void)
59 {
60 static const int mib[2] = { CTL_KERN, KERN_ARND };
61 size_t len;
62
63 if (__stack_chk_guard[0] != 0)
64 return;
65
66 len = sizeof(__stack_chk_guard);
67 if (__sysctl(mib, (u_int)__arraycount(mib), __stack_chk_guard, &len,
68 NULL, 0) == -1 || len != sizeof(__stack_chk_guard)) {
69 /* If sysctl was unsuccessful, use the "terminator canary". */
70 ((unsigned char *)(void *)__stack_chk_guard)[0] = 0;
71 ((unsigned char *)(void *)__stack_chk_guard)[1] = 0;
72 ((unsigned char *)(void *)__stack_chk_guard)[2] = '\n';
73 ((unsigned char *)(void *)__stack_chk_guard)[3] = 255;
74 }
75 }
76
77 /*ARGSUSED*/
78 static void
__fail(const char * msg)79 __fail(const char *msg)
80 {
81 #ifdef _LIBC
82 struct syslog_data sdata = SYSLOG_DATA_INIT;
83 #endif
84 struct sigaction sa;
85 sigset_t mask;
86
87 /* Immediately block all signal handlers from running code */
88 (void)sigfillset(&mask);
89 (void)sigdelset(&mask, SIGABRT);
90 (void)sigprocmask(SIG_BLOCK, &mask, NULL);
91
92 #ifdef _LIBC
93 /* This may fail on a chroot jail... */
94 syslog_ss(LOG_CRIT, &sdata, "%s", msg);
95 #else
96 xprintf("%s: %s\n", getprogname(), msg);
97 #endif
98
99 (void)memset(&sa, 0, sizeof(sa));
100 (void)sigemptyset(&sa.sa_mask);
101 sa.sa_flags = 0;
102 sa.sa_handler = SIG_DFL;
103 (void)sigaction(SIGABRT, &sa, NULL);
104 (void)raise(SIGABRT);
105 _exit(127);
106 }
107
108 void
__stack_chk_fail(void)109 __stack_chk_fail(void)
110 {
111 __fail("stack overflow detected; terminated");
112 }
113
114 void
__chk_fail(void)115 __chk_fail(void)
116 {
117 __fail("buffer overflow detected; terminated");
118 }
119
120 void
__stack_chk_fail_local(void)121 __stack_chk_fail_local(void)
122 {
123 __stack_chk_fail();
124 }
125