264 lines
8.5 KiB
C++
264 lines
8.5 KiB
C++
/*
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* Copyright (C) 2008 The Android Open Source Project
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include "linker.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <signal.h>
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#include <sys/prctl.h>
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#include <errno.h>
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#include <sys/socket.h>
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#include <sys/un.h>
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#include <private/debug_format.h>
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#include <private/logd.h>
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extern "C" int tgkill(int tgid, int tid, int sig);
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#define DEBUGGER_SOCKET_NAME "android:debuggerd"
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enum debugger_action_t {
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// dump a crash
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DEBUGGER_ACTION_CRASH,
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// dump a tombstone file
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DEBUGGER_ACTION_DUMP_TOMBSTONE,
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// dump a backtrace only back to the socket
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DEBUGGER_ACTION_DUMP_BACKTRACE,
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};
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/* message sent over the socket */
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struct debugger_msg_t {
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debugger_action_t action;
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pid_t tid;
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};
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// see man(2) prctl, specifically the section about PR_GET_NAME
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#define MAX_TASK_NAME_LEN (16)
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static int socket_abstract_client(const char* name, int type) {
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sockaddr_un addr;
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// Test with length +1 for the *initial* '\0'.
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size_t namelen = strlen(name);
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if ((namelen + 1) > sizeof(addr.sun_path)) {
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errno = EINVAL;
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return -1;
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}
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/* This is used for abstract socket namespace, we need
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* an initial '\0' at the start of the Unix socket path.
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*
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* Note: The path in this case is *not* supposed to be
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* '\0'-terminated. ("man 7 unix" for the gory details.)
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*/
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memset(&addr, 0, sizeof(addr));
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addr.sun_family = AF_LOCAL;
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addr.sun_path[0] = 0;
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memcpy(addr.sun_path + 1, name, namelen);
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socklen_t alen = namelen + offsetof(sockaddr_un, sun_path) + 1;
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int s = socket(AF_LOCAL, type, 0);
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if (s == -1) {
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return -1;
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}
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int err = TEMP_FAILURE_RETRY(connect(s, (sockaddr*) &addr, alen));
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if (err == -1) {
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close(s);
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s = -1;
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}
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return s;
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}
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/*
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* Writes a summary of the signal to the log file. We do this so that, if
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* for some reason we're not able to contact debuggerd, there is still some
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* indication of the failure in the log.
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*
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* We could be here as a result of native heap corruption, or while a
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* mutex is being held, so we don't want to use any libc functions that
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* could allocate memory or hold a lock.
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*/
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static void logSignalSummary(int signum, const siginfo_t* info) {
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const char* signal_name;
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switch (signum) {
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case SIGILL: signal_name = "SIGILL"; break;
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case SIGABRT: signal_name = "SIGABRT"; break;
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case SIGBUS: signal_name = "SIGBUS"; break;
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case SIGFPE: signal_name = "SIGFPE"; break;
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case SIGSEGV: signal_name = "SIGSEGV"; break;
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#if defined(SIGSTKFLT)
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case SIGSTKFLT: signal_name = "SIGSTKFLT"; break;
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#endif
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case SIGPIPE: signal_name = "SIGPIPE"; break;
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default: signal_name = "???"; break;
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}
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char thread_name[MAX_TASK_NAME_LEN + 1]; // one more for termination
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if (prctl(PR_GET_NAME, (unsigned long)thread_name, 0, 0, 0) != 0) {
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strcpy(thread_name, "<name unknown>");
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} else {
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// short names are null terminated by prctl, but the man page
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// implies that 16 byte names are not.
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thread_name[MAX_TASK_NAME_LEN] = 0;
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}
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// "info" will be NULL if the siginfo_t information was not available.
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if (info != NULL) {
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__libc_format_log(ANDROID_LOG_FATAL, "libc",
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"Fatal signal %d (%s) at 0x%08x (code=%d), thread %d (%s)",
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signum, signal_name, reinterpret_cast<uintptr_t>(info->si_addr),
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info->si_code, gettid(), thread_name);
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} else {
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__libc_format_log(ANDROID_LOG_FATAL, "libc",
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"Fatal signal %d (%s), thread %d (%s)",
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signum, signal_name, gettid(), thread_name);
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}
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}
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/*
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* Returns true if the handler for signal "signum" has SA_SIGINFO set.
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*/
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static bool haveSiginfo(int signum) {
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struct sigaction oldact, newact;
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memset(&newact, 0, sizeof(newact));
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newact.sa_handler = SIG_DFL;
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newact.sa_flags = SA_RESTART;
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sigemptyset(&newact.sa_mask);
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if (sigaction(signum, &newact, &oldact) < 0) {
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__libc_android_log_write(ANDROID_LOG_FATAL, "libc",
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"Failed testing for SA_SIGINFO");
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return 0;
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}
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bool ret = (oldact.sa_flags & SA_SIGINFO) != 0;
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if (sigaction(signum, &oldact, NULL) < 0) {
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__libc_android_log_write(ANDROID_LOG_FATAL, "libc",
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"Restore failed in test for SA_SIGINFO");
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}
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return ret;
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}
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/*
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* Catches fatal signals so we can ask debuggerd to ptrace us before
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* we crash.
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*/
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void debugger_signal_handler(int n, siginfo_t* info, void*) {
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/*
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* It's possible somebody cleared the SA_SIGINFO flag, which would mean
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* our "info" arg holds an undefined value.
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*/
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if (!haveSiginfo(n)) {
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info = NULL;
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}
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logSignalSummary(n, info);
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pid_t tid = gettid();
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int s = socket_abstract_client(DEBUGGER_SOCKET_NAME, SOCK_STREAM);
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if (s >= 0) {
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/* debugger knows our pid from the credentials on the
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* local socket but we need to tell it our tid. It
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* is paranoid and will verify that we are giving a tid
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* that's actually in our process
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*/
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int ret;
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debugger_msg_t msg;
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msg.action = DEBUGGER_ACTION_CRASH;
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msg.tid = tid;
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ret = TEMP_FAILURE_RETRY(write(s, &msg, sizeof(msg)));
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if (ret == sizeof(msg)) {
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/* if the write failed, there is no point to read on
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* the file descriptor. */
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ret = TEMP_FAILURE_RETRY(read(s, &tid, 1));
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int saved_errno = errno;
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notify_gdb_of_libraries();
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errno = saved_errno;
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}
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if (ret < 0) {
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/* read or write failed -- broken connection? */
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__libc_format_log(ANDROID_LOG_FATAL, "libc", "Failed while talking to debuggerd: %s",
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strerror(errno));
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}
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close(s);
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} else {
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/* socket failed; maybe process ran out of fds */
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__libc_format_log(ANDROID_LOG_FATAL, "libc", "Unable to open connection to debuggerd: %s",
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strerror(errno));
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}
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/* remove our net so we fault for real when we return */
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signal(n, SIG_DFL);
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/*
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* These signals are not re-thrown when we resume. This means that
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* crashing due to (say) SIGPIPE doesn't work the way you'd expect it
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* to. We work around this by throwing them manually. We don't want
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* to do this for *all* signals because it'll screw up the address for
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* faults like SIGSEGV.
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*/
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switch (n) {
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case SIGABRT:
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case SIGFPE:
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case SIGPIPE:
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#ifdef SIGSTKFLT
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case SIGSTKFLT:
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#endif
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(void) tgkill(getpid(), gettid(), n);
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break;
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default: // SIGILL, SIGBUS, SIGSEGV
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break;
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}
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}
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void debugger_init() {
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struct sigaction act;
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memset(&act, 0, sizeof(act));
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act.sa_sigaction = debugger_signal_handler;
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act.sa_flags = SA_RESTART | SA_SIGINFO;
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sigemptyset(&act.sa_mask);
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sigaction(SIGILL, &act, NULL);
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sigaction(SIGABRT, &act, NULL);
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sigaction(SIGBUS, &act, NULL);
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sigaction(SIGFPE, &act, NULL);
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sigaction(SIGSEGV, &act, NULL);
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#if defined(SIGSTKFLT)
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sigaction(SIGSTKFLT, &act, NULL);
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#endif
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sigaction(SIGPIPE, &act, NULL);
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}
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