/* * 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 extern "C" int tgkill(int tgid, int tid, int sig); #define DEBUGGER_SOCKET_NAME "android:debuggerd" 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 { debugger_action_t action; pid_t tid; }; // 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 err = TEMP_FAILURE_RETRY(connect(s, (sockaddr*) &addr, alen)); if (err == -1) { close(s); s = -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 logSignalSummary(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 0x%08x (code=%d), thread %d (%s)", signum, signal_name, reinterpret_cast(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 haveSiginfo(int signum) { struct sigaction oldact, newact; memset(&newact, 0, sizeof(newact)); newact.sa_handler = SIG_DFL; newact.sa_flags = SA_RESTART; sigemptyset(&newact.sa_mask); if (sigaction(signum, &newact, &oldact) < 0) { __libc_format_log(ANDROID_LOG_FATAL, "libc", "Failed testing for SA_SIGINFO: %s", strerror(errno)); return 0; } bool ret = (oldact.sa_flags & SA_SIGINFO) != 0; if (sigaction(signum, &oldact, NULL) == -1) { __libc_format_log(ANDROID_LOG_FATAL, "libc", "Restore failed in test for SA_SIGINFO: %s", strerror(errno)); } return ret; } /* * Catches fatal signals so we can ask debuggerd to ptrace us before * we crash. */ void debuggerd_signal_handler(int n, siginfo_t* info, void*) { /* * It's possible somebody cleared the SA_SIGINFO flag, which would mean * our "info" arg holds an undefined value. */ if (!haveSiginfo(n)) { info = NULL; } logSignalSummary(n, info); pid_t tid = gettid(); int s = socket_abstract_client(DEBUGGER_SOCKET_NAME, SOCK_STREAM); if (s >= 0) { /* debugger knows our pid from the credentials on the * local socket but we need to tell it our tid. It * is paranoid and will verify that we are giving a tid * that's actually in our process */ int ret; debugger_msg_t msg; msg.action = DEBUGGER_ACTION_CRASH; msg.tid = tid; ret = TEMP_FAILURE_RETRY(write(s, &msg, sizeof(msg))); if (ret == sizeof(msg)) { /* if the write failed, there is no point to read on * the file descriptor. */ ret = TEMP_FAILURE_RETRY(read(s, &tid, 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(n, 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 (n) { case SIGABRT: case SIGFPE: case SIGPIPE: #ifdef SIGSTKFLT case SIGSTKFLT: #endif (void) tgkill(getpid(), gettid(), n); break; default: // SIGILL, SIGBUS, SIGSEGV break; } } void debuggerd_init() { struct sigaction act; memset(&act, 0, sizeof(act)); act.sa_sigaction = debuggerd_signal_handler; act.sa_flags = SA_RESTART | SA_SIGINFO; sigemptyset(&act.sa_mask); sigaction(SIGILL, &act, NULL); sigaction(SIGABRT, &act, NULL); sigaction(SIGBUS, &act, NULL); sigaction(SIGFPE, &act, NULL); sigaction(SIGSEGV, &act, NULL); #if defined(SIGSTKFLT) sigaction(SIGSTKFLT, &act, NULL); #endif sigaction(SIGPIPE, &act, NULL); }