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/* $OpenBSD: stack_protector.c,v 1.7 2004/09/14 22:19:30 deraadt Exp $ */
/*
* Copyright (c) 2002 Hiroaki Etoh, Federico G. Schwindt, and Miodrag Vallat.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
*/
#if defined(LIBC_SCCS) && !defined(list)
static char rcsid[] = "$OpenBSD: stack_protector.c,v 1.7 2004/09/14 22:19:30 deraadt Exp $";
#endif
#include <sys/param.h>
#include <sys/sysctl.h>
#include <signal.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
extern int __sysctl(int *, u_int, void *, size_t *, void *, size_t);
long __guard[8] = {0, 0, 0, 0, 0, 0, 0, 0};
static void __guard_setup(void) __attribute__ ((constructor));
void __stack_smash_handler(char func[], int damaged __attribute__((unused)));
static void
__guard_setup(void)
{
int i, mib[2];
size_t len;
if (__guard[0] != 0)
return;
mib[0] = CTL_KERN;
mib[1] = KERN_ARND;
len = 4;
for (i = 0; i < sizeof(__guard) / 4; i++) {
if (__sysctl(mib, 2, (char *)&((int *)__guard)[i],
&len, NULL, 0) == -1)
break;
}
if (i < sizeof(__guard) / 4) {
/* If sysctl was unsuccessful, use the "terminator canary". */
((unsigned char *)__guard)[0] = 0;
((unsigned char *)__guard)[1] = 0;
((unsigned char *)__guard)[2] = '\n';
((unsigned char *)__guard)[3] = 255;
}
}
void
__stack_smash_handler(char func[], int damaged)
{
struct syslog_data sdata = SYSLOG_DATA_INIT;
const char message[] = "stack overflow in function %s";
struct sigaction sa;
sigset_t mask;
/* Immediately block all signal handlers from running code */
sigfillset(&mask);
sigdelset(&mask, SIGABRT);
sigprocmask(SIG_BLOCK, &mask, NULL);
/* This may fail on a chroot jail... */
syslog_r(LOG_CRIT, &sdata, message, func);
bzero(&sa, sizeof(struct sigaction));
sigemptyset(&sa.sa_mask);
sa.sa_flags = 0;
sa.sa_handler = SIG_DFL;
sigaction(SIGABRT, &sa, NULL);
kill(getpid(), SIGABRT);
_exit(127);
}
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