1/*
2 * Copyright (C) 2008 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *  * Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 *  * Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in
12 *    the documentation and/or other materials provided with the
13 *    distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28#include <stdio.h>
29#include <stdlib.h>
30#include <signal.h>
31#include <string.h>
32#include <unistd.h>
33#include <fcntl.h>
34#include <ctype.h>
35#include "logd.h"
36
37void *__stack_chk_guard = 0;
38
39/* Initialize the canary with a random value from /dev/urandom.
40 * If that fails, use the "terminator canary". */
41static void __attribute__ ((constructor))
42__guard_setup(void)
43{
44    int fd;
45
46    fd = open("/dev/urandom", O_RDONLY);
47    if (fd != -1) {
48        ssize_t len = read(fd, &__stack_chk_guard,
49                           sizeof(__stack_chk_guard));
50        close(fd);
51        if (len == sizeof(__stack_chk_guard))
52            return;
53    }
54
55    /* If that failed, switch to 'terminator canary' */
56    ((unsigned char *)&__stack_chk_guard)[0] = 0;
57    ((unsigned char *)&__stack_chk_guard)[1] = 0;
58    ((unsigned char *)&__stack_chk_guard)[2] = '\n';
59    ((unsigned char *)&__stack_chk_guard)[3] = 255;
60}
61
62/* This is the crash handler.
63 * Does a best effort at logging and calls _exit to terminate
64 * the process immediately (without atexit handlers, etc.) */
65void __stack_chk_fail(void)
66{
67    struct sigaction sa;
68    sigset_t sigmask;
69    static const char message[] = "stack corruption detected: aborted";
70    char path[PATH_MAX];
71    int count;
72
73    /* Immediately block all (but SIGABRT) signal handlers from running code */
74    sigfillset(&sigmask);
75    sigdelset(&sigmask, SIGABRT);
76    sigprocmask(SIG_BLOCK, &sigmask, NULL);
77
78    /* Use /proc/self/exe link to obtain the program name for logging
79     * purposes. If it's not available, we set it to "<unknown>" */
80    if ((count = readlink("/proc/self/exe", path, sizeof(path) - 1)) == -1) {
81        strlcpy(path, "<unknown>", sizeof(path));
82    } else {
83        path[count] = '\0';
84    }
85
86    /* Do a best effort at logging. This ends up calling writev(2) */
87    __libc_android_log_print(ANDROID_LOG_FATAL, path, message);
88
89    /* Make sure there is no default action for SIGABRT */
90    bzero(&sa, sizeof(struct sigaction));
91    sigemptyset(&sa.sa_mask);
92    sa.sa_flags = 0;
93    sa.sa_handler = SIG_DFL;
94    sigaction(SIGABRT, &sa, NULL);
95
96    /* Terminate the process and exit immediately */
97    kill(getpid(), SIGABRT);
98
99    _exit(127);
100}
101