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Annotation of src/lib/libc/misc/stack_protector.c, Revision 1.2

1.2     ! ad          1: /*     $NetBSD: stack_protector.c,v 1.1 2007/11/13 15:21:20 ad Exp $   */
1.1       ad          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>
1.2     ! ad         31: __RCSID("$NetBSD: stack_protector.c,v 1.1 2007/11/13 15:21:20 ad Exp $");
1.1       ad         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
1.2     ! ad         47: void xprintf(const char *fmt, ...);
1.1       ad         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 *);
                     53: void __stack_chk_fail(void);
                     54: void __chk_fail(void);
                     55: void __stack_chk_fail_local(void);
                     56: void __guard_setup(void);
                     57:
                     58: void
                     59: __guard_setup(void)
                     60: {
                     61:        int mib[2];
                     62:        size_t len;
                     63:
                     64:        if (__stack_chk_guard[0] != 0)
                     65:                return;
                     66:
                     67:        mib[0] = CTL_KERN;
                     68:        mib[1] = KERN_ARND;
                     69:
                     70:        len = sizeof(__stack_chk_guard);
                     71:        if (__sysctl(mib, 2, __stack_chk_guard, &len, NULL, 0) == -1 ||
                     72:            len != sizeof(__stack_chk_guard)) {
                     73:                /* If sysctl was unsuccessful, use the "terminator canary". */
                     74:                ((unsigned char *)(void *)__stack_chk_guard)[0] = 0;
                     75:                ((unsigned char *)(void *)__stack_chk_guard)[1] = 0;
                     76:                ((unsigned char *)(void *)__stack_chk_guard)[2] = '\n';
                     77:                ((unsigned char *)(void *)__stack_chk_guard)[3] = 255;
                     78:        }
                     79: }
                     80:
                     81: /*ARGSUSED*/
                     82: static void
                     83: __fail(const char *msg)
                     84: {
                     85: #ifdef _LIBC
                     86:        struct syslog_data sdata = SYSLOG_DATA_INIT;
                     87: #endif
                     88:        struct sigaction sa;
                     89:        sigset_t mask;
                     90:
                     91:        /* Immediately block all signal handlers from running code */
                     92:        (void)sigfillset(&mask);
                     93:        (void)sigdelset(&mask, SIGABRT);
                     94:        (void)sigprocmask(SIG_BLOCK, &mask, NULL);
                     95:
                     96: #ifdef _LIBC
                     97:        /* This may fail on a chroot jail... */
                     98:        syslog_ss(LOG_CRIT, &sdata, msg);
                     99: #else
                    100:        xprintf("%s: %s\n", getprogname(), msg);
                    101: #endif
                    102:
                    103:        (void)memset(&sa, 0, sizeof(sa));
                    104:        (void)sigemptyset(&sa.sa_mask);
                    105:        sa.sa_flags = 0;
                    106:        sa.sa_handler = SIG_DFL;
                    107:        (void)sigaction(SIGABRT, &sa, NULL);
                    108:        (void)kill(getpid(), SIGABRT);
                    109:        _exit(127);
                    110: }
                    111:
                    112: void
                    113: __stack_chk_fail(void)
                    114: {
                    115:        __fail("stack overflow detected; terminated");
                    116: }
                    117:
                    118: void
                    119: __chk_fail(void)
                    120: {
                    121:        __fail("buffer overflow detected; terminated");
                    122: }
                    123:
                    124: void
                    125: __stack_chk_fail_local(void)
                    126: {
                    127:        __stack_chk_fail();
                    128: }

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