/* * Copyright (C) 2008 The Android Open Source Project * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * 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 COPYRIGHT HOLDERS AND CONTRIBUTORS * "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 * COPYRIGHT OWNER OR CONTRIBUTORS 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. */ #include "linker.h" #include #include #include #include #include #include #include #include #include extern "C" int tgkill(int tgid, int tid, int sig); #if __LP64__ #define DEBUGGER_SOCKET_NAME "android:debuggerd64" #else #define DEBUGGER_SOCKET_NAME "android:debuggerd" #endif enum debugger_action_t { // dump a crash DEBUGGER_ACTION_CRASH, // dump a tombstone file DEBUGGER_ACTION_DUMP_TOMBSTONE, // dump a backtrace only back to the socket DEBUGGER_ACTION_DUMP_BACKTRACE, }; /* message sent over the socket */ struct debugger_msg_t { // version 1 included: debugger_action_t action; pid_t tid; // version 2 added: uintptr_t abort_msg_address; }; // see man(2) prctl, specifically the section about PR_GET_NAME #define MAX_TASK_NAME_LEN (16) static int socket_abstract_client(const char* name, int type) { sockaddr_un addr; // Test with length +1 for the *initial* '\0'. size_t namelen = strlen(name); if ((namelen + 1) > sizeof(addr.sun_path)) { errno = EINVAL; return -1; } /* This is used for abstract socket namespace, we need * an initial '\0' at the start of the Unix socket path. * * Note: The path in this case is *not* supposed to be * '\0'-terminated. ("man 7 unix" for the gory details.) */ memset(&addr, 0, sizeof(addr)); addr.sun_family = AF_LOCAL; addr.sun_path[0] = 0; memcpy(addr.sun_path + 1, name, namelen); socklen_t alen = namelen + offsetof(sockaddr_un, sun_path) + 1; int s = socket(AF_LOCAL, type, 0); if (s == -1) { return -1; } int rc = TEMP_FAILURE_RETRY(connect(s, reinterpret_cast(&addr), alen)); if (rc == -1) { close(s); return -1; } return s; } /* * Writes a summary of the signal to the log file. We do this so that, if * for some reason we're not able to contact debuggerd, there is still some * indication of the failure in the log. * * We could be here as a result of native heap corruption, or while a * mutex is being held, so we don't want to use any libc functions that * could allocate memory or hold a lock. */ static void log_signal_summary(int signum, const siginfo_t* info) { const char* signal_name; switch (signum) { case SIGILL: signal_name = "SIGILL"; break; case SIGABRT: signal_name = "SIGABRT"; break; case SIGBUS: signal_name = "SIGBUS"; break; case SIGFPE: signal_name = "SIGFPE"; break; case SIGSEGV: signal_name = "SIGSEGV"; break; #if defined(SIGSTKFLT) case SIGSTKFLT: signal_name = "SIGSTKFLT"; break; #endif case SIGPIPE: signal_name = "SIGPIPE"; break; default: signal_name = "???"; break; } char thread_name[MAX_TASK_NAME_LEN + 1]; // one more for termination if (prctl(PR_GET_NAME, (unsigned long)thread_name, 0, 0, 0) != 0) { strcpy(thread_name, ""); } else { // short names are null terminated by prctl, but the man page // implies that 16 byte names are not. thread_name[MAX_TASK_NAME_LEN] = 0; } // "info" will be NULL if the siginfo_t information was not available. if (info != NULL) { __libc_format_log(ANDROID_LOG_FATAL, "libc", "Fatal signal %d (%s) at %p (code=%d), thread %d (%s)", signum, signal_name, info->si_addr, info->si_code, gettid(), thread_name); } else { __libc_format_log(ANDROID_LOG_FATAL, "libc", "Fatal signal %d (%s), thread %d (%s)", signum, signal_name, gettid(), thread_name); } } /* * Returns true if the handler for signal "signum" has SA_SIGINFO set. */ static bool have_siginfo(int signum) { struct sigaction old_action, new_action; memset(&new_action, 0, sizeof(new_action)); new_action.sa_handler = SIG_DFL; new_action.sa_flags = SA_RESTART; sigemptyset(&new_action.sa_mask); if (sigaction(signum, &new_action, &old_action) < 0) { __libc_format_log(ANDROID_LOG_WARN, "libc", "Failed testing for SA_SIGINFO: %s", strerror(errno)); return false; } bool result = (old_action.sa_flags & SA_SIGINFO) != 0; if (sigaction(signum, &old_action, NULL) == -1) { __libc_format_log(ANDROID_LOG_WARN, "libc", "Restore failed in test for SA_SIGINFO: %s", strerror(errno)); } return result; } /* * Catches fatal signals so we can ask debuggerd to ptrace us before * we crash. */ void debuggerd_signal_handler(int signal_number, siginfo_t* info, void*) { // It's possible somebody cleared the SA_SIGINFO flag, which would mean // our "info" arg holds an undefined value. if (!have_siginfo(signal_number)) { info = NULL; } log_signal_summary(signal_number, info); int s = socket_abstract_client(DEBUGGER_SOCKET_NAME, SOCK_STREAM); if (s != -1) { // debuggerd knows our pid from the credentials on the // local socket but we need to tell it the tid of the crashing thread. // debuggerd will be paranoid and verify that we sent a tid // that's actually in our process. debugger_msg_t msg; msg.action = DEBUGGER_ACTION_CRASH; msg.tid = gettid(); msg.abort_msg_address = reinterpret_cast(gAbortMessage); int ret = TEMP_FAILURE_RETRY(write(s, &msg, sizeof(msg))); if (ret == sizeof(msg)) { // If the write failed, there is no point trying to read a response. char debuggerd_ack; ret = TEMP_FAILURE_RETRY(read(s, &debuggerd_ack, 1)); int saved_errno = errno; notify_gdb_of_libraries(); errno = saved_errno; } if (ret < 0) { // read or write failed -- broken connection? __libc_format_log(ANDROID_LOG_FATAL, "libc", "Failed while talking to debuggerd: %s", strerror(errno)); } close(s); } else { // socket failed; maybe process ran out of fds? __libc_format_log(ANDROID_LOG_FATAL, "libc", "Unable to open connection to debuggerd: %s", strerror(errno)); } // Remove our net so we fault for real when we return. signal(signal_number, SIG_DFL); // These signals are not re-thrown when we resume. This means that // crashing due to (say) SIGPIPE doesn't work the way you'd expect it // to. We work around this by throwing them manually. We don't want // to do this for *all* signals because it'll screw up the address for // faults like SIGSEGV. switch (signal_number) { case SIGABRT: case SIGFPE: case SIGPIPE: #if defined(SIGSTKFLT) case SIGSTKFLT: #endif tgkill(getpid(), gettid(), signal_number); break; default: // SIGILL, SIGBUS, SIGSEGV break; } } void debuggerd_init() { struct sigaction action; memset(&action, 0, sizeof(action)); sigemptyset(&action.sa_mask); action.sa_sigaction = debuggerd_signal_handler; action.sa_flags = SA_RESTART | SA_SIGINFO; // Use the alternate signal stack if available so we can catch stack overflows. action.sa_flags |= SA_ONSTACK; sigaction(SIGABRT, &action, NULL); sigaction(SIGBUS, &action, NULL); sigaction(SIGFPE, &action, NULL); sigaction(SIGILL, &action, NULL); sigaction(SIGPIPE, &action, NULL); sigaction(SIGSEGV, &action, NULL); #if defined(SIGSTKFLT) sigaction(SIGSTKFLT, &action, NULL); #endif sigaction(SIGTRAP, &action, NULL); }