/* * Copyright 2016, The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define ATRACE_TAG ATRACE_TAG_BIONIC #include #include #include #include #include "libdebuggerd/backtrace.h" #include "libdebuggerd/tombstone.h" #include "libdebuggerd/utility.h" #include "debuggerd/handler.h" #include "tombstone_handler.h" #include "protocol.h" #include "util.h" using android::base::ErrnoRestorer; using android::base::StringPrintf; using android::base::unique_fd; static bool pid_contains_tid(int pid_proc_fd, pid_t tid) { struct stat st; std::string task_path = StringPrintf("task/%d", tid); return fstatat(pid_proc_fd, task_path.c_str(), &st, 0) == 0; } static pid_t get_tracer(pid_t tracee) { // Check to see if the thread is being ptraced by another process. android::procinfo::ProcessInfo process_info; if (android::procinfo::GetProcessInfo(tracee, &process_info)) { return process_info.tracer; } return -1; } // Attach to a thread, and verify that it's still a member of the given process static bool ptrace_seize_thread(int pid_proc_fd, pid_t tid, std::string* error, int flags = 0) { if (ptrace(PTRACE_SEIZE, tid, 0, flags) != 0) { if (errno == EPERM) { ErrnoRestorer errno_restorer; // In case get_tracer() fails and we fall through. pid_t tracer_pid = get_tracer(tid); if (tracer_pid > 0) { *error = StringPrintf("failed to attach to thread %d, already traced by %d (%s)", tid, tracer_pid, get_process_name(tracer_pid).c_str()); return false; } } *error = StringPrintf("failed to attach to thread %d: %s", tid, strerror(errno)); return false; } // Make sure that the task we attached to is actually part of the pid we're dumping. if (!pid_contains_tid(pid_proc_fd, tid)) { if (ptrace(PTRACE_DETACH, tid, 0, 0) != 0) { PLOG(WARNING) << "failed to detach from thread " << tid; } *error = StringPrintf("thread %d is not in process", tid); return false; } return true; } static bool wait_for_stop(pid_t tid, int* received_signal) { while (true) { int status; pid_t result = waitpid(tid, &status, __WALL); if (result != tid) { PLOG(ERROR) << "waitpid failed on " << tid << " while detaching"; return false; } if (WIFSTOPPED(status)) { if (status >> 16 == PTRACE_EVENT_STOP) { *received_signal = 0; } else { *received_signal = WSTOPSIG(status); } return true; } } } // Interrupt a process and wait for it to be interrupted. static bool ptrace_interrupt(pid_t tid, int* received_signal) { if (ptrace(PTRACE_INTERRUPT, tid, 0, 0) == 0) { return wait_for_stop(tid, received_signal); } PLOG(ERROR) << "failed to interrupt " << tid << " to detach"; return false; } static bool activity_manager_notify(pid_t pid, int signal, const std::string& amfd_data, bool recoverable_gwp_asan_crash) { ATRACE_CALL(); android::base::unique_fd amfd(socket_local_client( "/data/system/ndebugsocket", ANDROID_SOCKET_NAMESPACE_FILESYSTEM, SOCK_STREAM)); if (amfd.get() == -1) { PLOG(ERROR) << "unable to connect to activity manager"; return false; } struct timeval tv = { .tv_sec = 1 * android::base::HwTimeoutMultiplier(), .tv_usec = 0, }; if (setsockopt(amfd.get(), SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv)) == -1) { PLOG(ERROR) << "failed to set send timeout on activity manager socket"; return false; } tv.tv_sec = 3 * android::base::HwTimeoutMultiplier(); // 3 seconds on handshake read if (setsockopt(amfd.get(), SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv)) == -1) { PLOG(ERROR) << "failed to set receive timeout on activity manager socket"; return false; } // Activity Manager protocol: // - 32-bit network-byte-order: pid // - 32-bit network-byte-order: signal number // - byte: recoverable_gwp_asan_crash // - bytes: raw text of the dump // - null terminator uint32_t datum = htonl(pid); if (!android::base::WriteFully(amfd, &datum, sizeof(datum))) { PLOG(ERROR) << "AM pid write failed"; return false; } datum = htonl(signal); if (!android::base::WriteFully(amfd, &datum, sizeof(datum))) { PLOG(ERROR) << "AM signo write failed"; return false; } uint8_t recoverable_gwp_asan_crash_byte = recoverable_gwp_asan_crash ? 1 : 0; if (!android::base::WriteFully(amfd, &recoverable_gwp_asan_crash_byte, sizeof(recoverable_gwp_asan_crash_byte))) { PLOG(ERROR) << "AM recoverable_gwp_asan_crash_byte write failed"; return false; } if (!android::base::WriteFully(amfd, amfd_data.c_str(), amfd_data.size() + 1)) { PLOG(ERROR) << "AM data write failed"; return false; } // 3 sec timeout reading the ack; we're fine if the read fails. char ack; android::base::ReadFully(amfd, &ack, 1); return true; } // Globals used by the abort handler. static pid_t g_target_thread = -1; static bool g_tombstoned_connected = false; static unique_fd g_tombstoned_socket; static unique_fd g_output_fd; static unique_fd g_proto_fd; static void DefuseSignalHandlers() { // Don't try to dump ourselves. struct sigaction action = {}; action.sa_handler = SIG_DFL; debuggerd_register_handlers(&action); sigset_t mask; sigemptyset(&mask); if (sigprocmask(SIG_SETMASK, &mask, nullptr) != 0) { PLOG(FATAL) << "failed to set signal mask"; } } static void Initialize(char** argv) { android::base::InitLogging(argv); android::base::SetAborter([](const char* abort_msg) { // If we abort before we get an output fd, contact tombstoned to let any // potential listeners know that we failed. if (!g_tombstoned_connected) { if (!connect_tombstone_server(g_target_thread, &g_tombstoned_socket, &g_output_fd, &g_proto_fd, kDebuggerdAnyIntercept)) { // We failed to connect, not much we can do. LOG(ERROR) << "failed to connected to tombstoned to report failure"; _exit(1); } } dprintf(g_output_fd.get(), "crash_dump failed to dump process"); if (g_target_thread != 1) { dprintf(g_output_fd.get(), " %d: %s\n", g_target_thread, abort_msg); } else { dprintf(g_output_fd.get(), ": %s\n", abort_msg); } _exit(1); }); } static void ParseArgs(int argc, char** argv, pid_t* pseudothread_tid, DebuggerdDumpType* dump_type) { if (argc != 4) { LOG(FATAL) << "wrong number of args: " << argc << " (expected 4)"; } if (!android::base::ParseInt(argv[1], &g_target_thread, 1, std::numeric_limits::max())) { LOG(FATAL) << "invalid target tid: " << argv[1]; } if (!android::base::ParseInt(argv[2], pseudothread_tid, 1, std::numeric_limits::max())) { LOG(FATAL) << "invalid pseudothread tid: " << argv[2]; } int dump_type_int; if (!android::base::ParseInt(argv[3], &dump_type_int, 0)) { LOG(FATAL) << "invalid requested dump type: " << argv[3]; } *dump_type = static_cast(dump_type_int); switch (*dump_type) { case kDebuggerdNativeBacktrace: case kDebuggerdTombstone: case kDebuggerdTombstoneProto: break; default: LOG(FATAL) << "invalid requested dump type: " << dump_type_int; } } static void ReadCrashInfo(unique_fd& fd, siginfo_t* siginfo, std::unique_ptr* regs, ProcessInfo* process_info, bool* recoverable_gwp_asan_crash) { std::aligned_storage::type buf; CrashInfo* crash_info = reinterpret_cast(&buf); ssize_t rc = TEMP_FAILURE_RETRY(read(fd.get(), &buf, sizeof(buf))); *recoverable_gwp_asan_crash = false; if (rc == -1) { PLOG(FATAL) << "failed to read target ucontext"; } else { ssize_t expected_size = 0; switch (crash_info->header.version) { case 1: case 2: case 3: expected_size = sizeof(CrashInfoHeader) + sizeof(CrashInfoDataStatic); break; case 4: expected_size = sizeof(CrashInfoHeader) + sizeof(CrashInfoDataDynamic); break; default: LOG(FATAL) << "unexpected CrashInfo version: " << crash_info->header.version; break; }; if (rc < expected_size) { LOG(FATAL) << "read " << rc << " bytes when reading target crash information, expected " << expected_size; } } switch (crash_info->header.version) { case 4: process_info->fdsan_table_address = crash_info->data.d.fdsan_table_address; process_info->gwp_asan_state = crash_info->data.d.gwp_asan_state; process_info->gwp_asan_metadata = crash_info->data.d.gwp_asan_metadata; process_info->scudo_stack_depot = crash_info->data.d.scudo_stack_depot; process_info->scudo_stack_depot_size = crash_info->data.d.scudo_stack_depot_size; process_info->scudo_region_info = crash_info->data.d.scudo_region_info; process_info->scudo_ring_buffer = crash_info->data.d.scudo_ring_buffer; process_info->scudo_ring_buffer_size = crash_info->data.d.scudo_ring_buffer_size; *recoverable_gwp_asan_crash = crash_info->data.d.recoverable_gwp_asan_crash; FALLTHROUGH_INTENDED; case 1: case 2: case 3: process_info->abort_msg_address = crash_info->data.s.abort_msg_address; *siginfo = crash_info->data.s.siginfo; if (signal_has_si_addr(siginfo)) { process_info->has_fault_address = true; process_info->maybe_tagged_fault_address = reinterpret_cast(siginfo->si_addr); process_info->untagged_fault_address = untag_address(reinterpret_cast(siginfo->si_addr)); } regs->reset(unwindstack::Regs::CreateFromUcontext(unwindstack::Regs::CurrentArch(), &crash_info->data.s.ucontext)); break; default: __builtin_unreachable(); } } // Wait for a process to clone and return the child's pid. // Note: this leaves the parent in PTRACE_EVENT_STOP. static pid_t wait_for_clone(pid_t pid, bool resume_child) { int status; pid_t result = TEMP_FAILURE_RETRY(waitpid(pid, &status, __WALL)); if (result == -1) { PLOG(FATAL) << "failed to waitpid"; } if (WIFEXITED(status)) { LOG(FATAL) << "traced process exited with status " << WEXITSTATUS(status); } else if (WIFSIGNALED(status)) { LOG(FATAL) << "traced process exited with signal " << WTERMSIG(status); } else if (!WIFSTOPPED(status)) { LOG(FATAL) << "process didn't stop? (status = " << status << ")"; } if (status >> 8 != (SIGTRAP | (PTRACE_EVENT_CLONE << 8))) { LOG(FATAL) << "process didn't stop due to PTRACE_O_TRACECLONE (status = " << status << ")"; } pid_t child; if (ptrace(PTRACE_GETEVENTMSG, pid, 0, &child) != 0) { PLOG(FATAL) << "failed to get child pid via PTRACE_GETEVENTMSG"; } int stop_signal; if (!wait_for_stop(child, &stop_signal)) { PLOG(FATAL) << "failed to waitpid on child"; } CHECK_EQ(0, stop_signal); if (resume_child) { if (ptrace(PTRACE_CONT, child, 0, 0) != 0) { PLOG(FATAL) << "failed to resume child (pid = " << child << ")"; } } return child; } static pid_t wait_for_vm_process(pid_t pseudothread_tid) { // The pseudothread will double-fork, we want its grandchild. pid_t intermediate = wait_for_clone(pseudothread_tid, true); pid_t vm_pid = wait_for_clone(intermediate, false); if (ptrace(PTRACE_DETACH, intermediate, 0, 0) != 0) { PLOG(FATAL) << "failed to detach from intermediate vm process"; } return vm_pid; } static void InstallSigPipeHandler() { struct sigaction action = {}; action.sa_handler = SIG_IGN; action.sa_flags = SA_RESTART; sigaction(SIGPIPE, &action, nullptr); } int main(int argc, char** argv) { DefuseSignalHandlers(); InstallSigPipeHandler(); // There appears to be a bug in the kernel where our death causes SIGHUP to // be sent to our process group if we exit while it has stopped jobs (e.g. // because of wait_for_debugger). Use setsid to create a new process group to // avoid hitting this. setsid(); atrace_begin(ATRACE_TAG, "before reparent"); pid_t target_process = getppid(); // Open /proc/`getppid()` before we daemonize. std::string target_proc_path = "/proc/" + std::to_string(target_process); int target_proc_fd = open(target_proc_path.c_str(), O_DIRECTORY | O_RDONLY); if (target_proc_fd == -1) { PLOG(FATAL) << "failed to open " << target_proc_path; } // Make sure getppid() hasn't changed. if (getppid() != target_process) { LOG(FATAL) << "parent died"; } atrace_end(ATRACE_TAG); // Reparent ourselves to init, so that the signal handler can waitpid on the // original process to avoid leaving a zombie for non-fatal dumps. // Move the input/output pipes off of stdout/stderr, out of paranoia. unique_fd output_pipe(dup(STDOUT_FILENO)); unique_fd input_pipe(dup(STDIN_FILENO)); unique_fd fork_exit_read, fork_exit_write; if (!Pipe(&fork_exit_read, &fork_exit_write)) { PLOG(FATAL) << "failed to create pipe"; } pid_t forkpid = fork(); if (forkpid == -1) { PLOG(FATAL) << "fork failed"; } else if (forkpid == 0) { fork_exit_read.reset(); } else { // We need the pseudothread to live until we get around to verifying the vm pid against it. // The last thing it does is block on a waitpid on us, so wait until our child tells us to die. fork_exit_write.reset(); char buf; TEMP_FAILURE_RETRY(read(fork_exit_read.get(), &buf, sizeof(buf))); _exit(0); } ATRACE_NAME("after reparent"); pid_t pseudothread_tid; DebuggerdDumpType dump_type; ProcessInfo process_info; Initialize(argv); ParseArgs(argc, argv, &pseudothread_tid, &dump_type); // Die if we take too long. // // Note: processes with many threads and minidebug-info can take a bit to // unwind, do not make this too small. b/62828735 alarm(30 * android::base::HwTimeoutMultiplier()); // Collect the list of open files. OpenFilesList open_files; { ATRACE_NAME("open files"); populate_open_files_list(&open_files, g_target_thread); } // In order to reduce the duration that we pause the process for, we ptrace // the threads, fetch their registers and associated information, and then // fork a separate process as a snapshot of the process's address space. std::set threads; if (!android::procinfo::GetProcessTids(g_target_thread, &threads)) { PLOG(FATAL) << "failed to get process threads"; } std::map thread_info; siginfo_t siginfo; std::string error; bool recoverable_gwp_asan_crash = false; { ATRACE_NAME("ptrace"); for (pid_t thread : threads) { // Trace the pseudothread separately, so we can use different options. if (thread == pseudothread_tid) { continue; } if (!ptrace_seize_thread(target_proc_fd, thread, &error)) { bool fatal = thread == g_target_thread; LOG(fatal ? FATAL : WARNING) << error; } ThreadInfo info; info.pid = target_process; info.tid = thread; info.uid = getuid(); info.thread_name = get_thread_name(thread); unique_fd attr_fd(openat(target_proc_fd, "attr/current", O_RDONLY | O_CLOEXEC)); if (!android::base::ReadFdToString(attr_fd, &info.selinux_label)) { PLOG(WARNING) << "failed to read selinux label"; } if (!ptrace_interrupt(thread, &info.signo)) { PLOG(WARNING) << "failed to ptrace interrupt thread " << thread; ptrace(PTRACE_DETACH, thread, 0, 0); continue; } struct iovec tagged_addr_iov = { &info.tagged_addr_ctrl, sizeof(info.tagged_addr_ctrl), }; if (ptrace(PTRACE_GETREGSET, thread, NT_ARM_TAGGED_ADDR_CTRL, reinterpret_cast(&tagged_addr_iov)) == -1) { info.tagged_addr_ctrl = -1; } struct iovec pac_enabled_keys_iov = { &info.pac_enabled_keys, sizeof(info.pac_enabled_keys), }; if (ptrace(PTRACE_GETREGSET, thread, NT_ARM_PAC_ENABLED_KEYS, reinterpret_cast(&pac_enabled_keys_iov)) == -1) { info.pac_enabled_keys = -1; } if (thread == g_target_thread) { // Read the thread's registers along with the rest of the crash info out of the pipe. ReadCrashInfo(input_pipe, &siginfo, &info.registers, &process_info, &recoverable_gwp_asan_crash); info.siginfo = &siginfo; info.signo = info.siginfo->si_signo; info.command_line = get_command_line(g_target_thread); } else { info.registers.reset(unwindstack::Regs::RemoteGet(thread)); if (!info.registers) { PLOG(WARNING) << "failed to fetch registers for thread " << thread; ptrace(PTRACE_DETACH, thread, 0, 0); continue; } } thread_info[thread] = std::move(info); } } // Trace the pseudothread with PTRACE_O_TRACECLONE and tell it to fork. if (!ptrace_seize_thread(target_proc_fd, pseudothread_tid, &error, PTRACE_O_TRACECLONE)) { LOG(FATAL) << "failed to seize pseudothread: " << error; } if (TEMP_FAILURE_RETRY(write(output_pipe.get(), "\1", 1)) != 1) { PLOG(FATAL) << "failed to write to pseudothread"; } pid_t vm_pid = wait_for_vm_process(pseudothread_tid); if (ptrace(PTRACE_DETACH, pseudothread_tid, 0, 0) != 0) { PLOG(FATAL) << "failed to detach from pseudothread"; } // The pseudothread can die now. fork_exit_write.reset(); // Defer the message until later, for readability. bool wait_for_debugger = android::base::GetBoolProperty( "debug.debuggerd.wait_for_debugger", android::base::GetBoolProperty("debug.debuggerd.wait_for_gdb", false)); if (siginfo.si_signo == BIONIC_SIGNAL_DEBUGGER) { wait_for_debugger = false; } // Detach from all of our attached threads before resuming. for (const auto& [tid, thread] : thread_info) { int resume_signal = thread.signo == BIONIC_SIGNAL_DEBUGGER ? 0 : thread.signo; if (wait_for_debugger) { resume_signal = 0; if (tgkill(target_process, tid, SIGSTOP) != 0) { PLOG(WARNING) << "failed to send SIGSTOP to " << tid; } } LOG(DEBUG) << "detaching from thread " << tid; if (ptrace(PTRACE_DETACH, tid, 0, resume_signal) != 0) { PLOG(ERROR) << "failed to detach from thread " << tid; } } // Drop our capabilities now that we've fetched all of the information we need. drop_capabilities(); { ATRACE_NAME("tombstoned_connect"); LOG(INFO) << "obtaining output fd from tombstoned, type: " << dump_type; g_tombstoned_connected = connect_tombstone_server(g_target_thread, &g_tombstoned_socket, &g_output_fd, &g_proto_fd, dump_type); } if (g_tombstoned_connected) { if (TEMP_FAILURE_RETRY(dup2(g_output_fd.get(), STDOUT_FILENO)) == -1) { PLOG(ERROR) << "failed to dup2 output fd (" << g_output_fd.get() << ") to STDOUT_FILENO"; } } else { unique_fd devnull(TEMP_FAILURE_RETRY(open("/dev/null", O_RDWR))); TEMP_FAILURE_RETRY(dup2(devnull.get(), STDOUT_FILENO)); g_output_fd = std::move(devnull); } LOG(INFO) << "performing dump of process " << target_process << " (target tid = " << g_target_thread << ")"; int signo = siginfo.si_signo; bool fatal_signal = signo != BIONIC_SIGNAL_DEBUGGER; bool backtrace = false; // si_value is special when used with BIONIC_SIGNAL_DEBUGGER. // 0: dump tombstone // 1: dump backtrace if (!fatal_signal) { int si_val = siginfo.si_value.sival_int; if (si_val == 0) { backtrace = false; } else if (si_val == 1) { backtrace = true; } else { LOG(WARNING) << "unknown si_value value " << si_val; } } // TODO: Use seccomp to lock ourselves down. unwindstack::AndroidRemoteUnwinder unwinder(vm_pid, unwindstack::Regs::CurrentArch()); unwindstack::ErrorData error_data; if (!unwinder.Initialize(error_data)) { LOG(FATAL) << "Failed to initialize unwinder object: " << unwindstack::GetErrorCodeString(error_data.code); } std::string amfd_data; if (backtrace) { ATRACE_NAME("dump_backtrace"); dump_backtrace(std::move(g_output_fd), &unwinder, thread_info, g_target_thread); } else { { ATRACE_NAME("fdsan table dump"); populate_fdsan_table(&open_files, unwinder.GetProcessMemory(), process_info.fdsan_table_address); } { ATRACE_NAME("engrave_tombstone"); engrave_tombstone(std::move(g_output_fd), std::move(g_proto_fd), &unwinder, thread_info, g_target_thread, process_info, &open_files, &amfd_data); } } if (fatal_signal) { // Don't try to notify ActivityManager if it just crashed, or we might hang until timeout. if (thread_info[target_process].thread_name != "system_server") { activity_manager_notify(target_process, signo, amfd_data, recoverable_gwp_asan_crash); } } if (wait_for_debugger) { // Use ALOGI to line up with output from engrave_tombstone. ALOGI( "***********************************************************\n" "* Process %d has been suspended while crashing.\n" "* To attach the debugger, run this on the host:\n" "*\n" "* lldbclient.py -p %d\n" "*\n" "***********************************************************", target_process, target_process); } // Close stdout before we notify tombstoned of completion. close(STDOUT_FILENO); if (g_tombstoned_connected && !notify_completion(g_tombstoned_socket.get(), g_output_fd.get(), g_proto_fd.get())) { LOG(ERROR) << "failed to notify tombstoned of completion"; } return 0; }