/thirdparty/breakpad/client/linux/handler/exception_handler.cc
http://github.com/tomahawk-player/tomahawk · C++ · 523 lines · 328 code · 65 blank · 130 comment · 58 complexity · 6b51de1e88bd892a94d2cf4e2b085c8a MD5 · raw file
- // Copyright (c) 2010 Google Inc.
- // 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.
- // * Neither the name of Google Inc. nor the names of its
- // contributors may be used to endorse or promote products derived from
- // this software without specific prior written permission.
- //
- // 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.
- // The ExceptionHandler object installs signal handlers for a number of
- // signals. We rely on the signal handler running on the thread which crashed
- // in order to identify it. This is true of the synchronous signals (SEGV etc),
- // but not true of ABRT. Thus, if you send ABRT to yourself in a program which
- // uses ExceptionHandler, you need to use tgkill to direct it to the current
- // thread.
- //
- // The signal flow looks like this:
- //
- // SignalHandler (uses a global stack of ExceptionHandler objects to find
- // | one to handle the signal. If the first rejects it, try
- // | the second etc...)
- // V
- // HandleSignal ----------------------------| (clones a new process which
- // | | shares an address space with
- // (wait for cloned | the crashed process. This
- // process) | allows us to ptrace the crashed
- // | | process)
- // V V
- // (set signal handler to ThreadEntry (static function to bounce
- // SIG_DFL and rethrow, | back into the object)
- // killing the crashed |
- // process) V
- // DoDump (writes minidump)
- // |
- // V
- // sys_exit
- //
- // This code is a little fragmented. Different functions of the ExceptionHandler
- // class run in a number of different contexts. Some of them run in a normal
- // context and are easy to code, others run in a compromised context and the
- // restrictions at the top of minidump_writer.cc apply: no libc and use the
- // alternative malloc. Each function should have comment above it detailing the
- // context which it runs in.
- #include "client/linux/handler/exception_handler.h"
- #include <errno.h>
- #include <fcntl.h>
- #include <linux/limits.h>
- #include <sched.h>
- #include <signal.h>
- #include <stdio.h>
- #include <sys/mman.h>
- #include <sys/prctl.h>
- #include <sys/syscall.h>
- #include <sys/wait.h>
- #include <unistd.h>
- #if !defined(__ANDROID__)
- #include <sys/signal.h>
- #include <sys/ucontext.h>
- #include <sys/user.h>
- #include <ucontext.h>
- #endif
- #include <algorithm>
- #include <utility>
- #include <vector>
- #include "common/linux/linux_libc_support.h"
- #include "common/memory.h"
- #include "client/linux/log/log.h"
- #include "client/linux/minidump_writer/linux_dumper.h"
- #include "client/linux/minidump_writer/minidump_writer.h"
- #include "common/linux/guid_creator.h"
- #include "common/linux/eintr_wrapper.h"
- #include "third_party/lss/linux_syscall_support.h"
- #include "linux/sched.h"
- #ifndef PR_SET_PTRACER
- #define PR_SET_PTRACER 0x59616d61
- #endif
- // A wrapper for the tgkill syscall: send a signal to a specific thread.
- static int tgkill(pid_t tgid, pid_t tid, int sig) {
- return syscall(__NR_tgkill, tgid, tid, sig);
- return 0;
- }
- namespace google_breakpad {
- // The list of signals which we consider to be crashes. The default action for
- // all these signals must be Core (see man 7 signal) because we rethrow the
- // signal after handling it and expect that it'll be fatal.
- static const int kExceptionSignals[] = {
- SIGSEGV, SIGABRT, SIGFPE, SIGILL, SIGBUS, -1
- };
- // We can stack multiple exception handlers. In that case, this is the global
- // which holds the stack.
- std::vector<ExceptionHandler*>* ExceptionHandler::handler_stack_ = NULL;
- unsigned ExceptionHandler::handler_stack_index_ = 0;
- pthread_mutex_t ExceptionHandler::handler_stack_mutex_ =
- PTHREAD_MUTEX_INITIALIZER;
- // Runs before crashing: normal context.
- ExceptionHandler::ExceptionHandler(const std::string &dump_path,
- FilterCallback filter,
- MinidumpCallback callback,
- void *callback_context,
- bool install_handler)
- : filter_(filter),
- callback_(callback),
- callback_context_(callback_context),
- handler_installed_(install_handler)
- {
- Init(dump_path, -1);
- }
- ExceptionHandler::ExceptionHandler(const std::string &dump_path,
- FilterCallback filter,
- MinidumpCallback callback,
- void* callback_context,
- bool install_handler,
- const int server_fd)
- : filter_(filter),
- callback_(callback),
- callback_context_(callback_context),
- handler_installed_(install_handler)
- {
- Init(dump_path, server_fd);
- }
- // Runs before crashing: normal context.
- ExceptionHandler::~ExceptionHandler() {
- UninstallHandlers();
- }
- void ExceptionHandler::Init(const std::string &dump_path,
- const int server_fd)
- {
- crash_handler_ = NULL;
- if (0 <= server_fd)
- crash_generation_client_
- .reset(CrashGenerationClient::TryCreate(server_fd));
- if (handler_installed_)
- InstallHandlers();
- if (!IsOutOfProcess())
- set_dump_path(dump_path);
- pthread_mutex_lock(&handler_stack_mutex_);
- if (handler_stack_ == NULL)
- handler_stack_ = new std::vector<ExceptionHandler *>;
- handler_stack_->push_back(this);
- pthread_mutex_unlock(&handler_stack_mutex_);
- }
- // Runs before crashing: normal context.
- bool ExceptionHandler::InstallHandlers() {
- // We run the signal handlers on an alternative stack because we might have
- // crashed because of a stack overflow.
- // We use this value rather than SIGSTKSZ because we would end up overrunning
- // such a small stack.
- static const unsigned kSigStackSize = 8192;
- stack_t stack;
- // Only set an alternative stack if there isn't already one, or if the current
- // one is too small.
- if (sys_sigaltstack(NULL, &stack) == -1 || !stack.ss_sp ||
- stack.ss_size < kSigStackSize) {
- memset(&stack, 0, sizeof(stack));
- stack.ss_sp = malloc(kSigStackSize);
- stack.ss_size = kSigStackSize;
- if (sys_sigaltstack(&stack, NULL) == -1)
- return false;
- }
- struct sigaction sa;
- memset(&sa, 0, sizeof(sa));
- sigemptyset(&sa.sa_mask);
- // mask all exception signals when we're handling one of them.
- for (unsigned i = 0; kExceptionSignals[i] != -1; ++i)
- sigaddset(&sa.sa_mask, kExceptionSignals[i]);
- sa.sa_sigaction = SignalHandler;
- sa.sa_flags = SA_ONSTACK | SA_SIGINFO;
- for (unsigned i = 0; kExceptionSignals[i] != -1; ++i) {
- struct sigaction* old = new struct sigaction;
- if (sigaction(kExceptionSignals[i], &sa, old) == -1)
- return false;
- old_handlers_.push_back(std::make_pair(kExceptionSignals[i], old));
- }
- return true;
- }
- // Runs before crashing: normal context.
- void ExceptionHandler::UninstallHandlers() {
- for (unsigned i = 0; i < old_handlers_.size(); ++i) {
- struct sigaction *action =
- reinterpret_cast<struct sigaction*>(old_handlers_[i].second);
- sigaction(old_handlers_[i].first, action, NULL);
- delete action;
- }
- pthread_mutex_lock(&handler_stack_mutex_);
- std::vector<ExceptionHandler*>::iterator handler =
- std::find(handler_stack_->begin(), handler_stack_->end(), this);
- handler_stack_->erase(handler);
- pthread_mutex_unlock(&handler_stack_mutex_);
- old_handlers_.clear();
- }
- // Runs before crashing: normal context.
- void ExceptionHandler::UpdateNextID() {
- GUID guid;
- char guid_str[kGUIDStringLength + 1];
- if (CreateGUID(&guid) && GUIDToString(&guid, guid_str, sizeof(guid_str))) {
- next_minidump_id_ = guid_str;
- next_minidump_id_c_ = next_minidump_id_.c_str();
- char minidump_path[PATH_MAX];
- snprintf(minidump_path, sizeof(minidump_path), "%s/%s.dmp",
- dump_path_c_,
- guid_str);
- next_minidump_path_ = minidump_path;
- next_minidump_path_c_ = next_minidump_path_.c_str();
- }
- }
- // void ExceptionHandler::set_crash_handler(HandlerCallback callback) {
- // crash_handler_ = callback;
- // }
- // This function runs in a compromised context: see the top of the file.
- // Runs on the crashing thread.
- // static
- void ExceptionHandler::SignalHandler(int sig, siginfo_t* info, void* uc) {
- // All the exception signals are blocked at this point.
- pthread_mutex_lock(&handler_stack_mutex_);
- if (!handler_stack_->size()) {
- pthread_mutex_unlock(&handler_stack_mutex_);
- return;
- }
- for (int i = handler_stack_->size() - 1; i >= 0; --i) {
- if ((*handler_stack_)[i]->HandleSignal(sig, info, uc)) {
- // successfully handled: We are in an invalid state since an exception
- // signal has been delivered. We don't call the exit handlers because
- // they could end up corrupting on-disk state.
- break;
- }
- }
- pthread_mutex_unlock(&handler_stack_mutex_);
- if (info->si_pid) {
- // This signal was triggered by somebody sending us the signal with kill().
- // In order to retrigger it, we have to queue a new signal by calling
- // kill() ourselves.
- if (tgkill(getpid(), syscall(__NR_gettid), sig) < 0) {
- // If we failed to kill ourselves (e.g. because a sandbox disallows us
- // to do so), we instead resort to terminating our process. This will
- // result in an incorrect exit code.
- _exit(1);
- }
- } else {
- // This was a synchronous signal triggered by a hard fault (e.g. SIGSEGV).
- // No need to reissue the signal. It will automatically trigger again,
- // when we return from the signal handler.
- }
- // As soon as we return from the signal handler, our signal will become
- // unmasked. At that time, we will get terminated with the same signal that
- // was triggered originally. This allows our parent to know that we crashed.
- // The default action for all the signals which we catch is Core, so
- // this is the end of us.
- signal(sig, SIG_DFL);
- }
- struct ThreadArgument {
- pid_t pid; // the crashing process
- ExceptionHandler* handler;
- const void* context; // a CrashContext structure
- size_t context_size;
- };
- // This is the entry function for the cloned process. We are in a compromised
- // context here: see the top of the file.
- // static
- int ExceptionHandler::ThreadEntry(void *arg) {
- const ThreadArgument *thread_arg = reinterpret_cast<ThreadArgument*>(arg);
- // Block here until the crashing process unblocks us when
- // we're allowed to use ptrace
- thread_arg->handler->WaitForContinueSignal();
- return thread_arg->handler->DoDump(thread_arg->pid, thread_arg->context,
- thread_arg->context_size) == false;
- }
- // This function runs in a compromised context: see the top of the file.
- // Runs on the crashing thread.
- bool ExceptionHandler::HandleSignal(int sig, siginfo_t* info, void* uc) {
- if (filter_ && !filter_(callback_context_))
- return false;
- // Allow ourselves to be dumped if the signal is trusted.
- bool signal_trusted = info->si_code > 0;
- bool signal_pid_trusted = info->si_code == SI_USER ||
- info->si_code == SI_TKILL;
- if (signal_trusted || (signal_pid_trusted && info->si_pid == getpid())) {
- sys_prctl(PR_SET_DUMPABLE, 1);
- }
- CrashContext context;
- memcpy(&context.siginfo, info, sizeof(siginfo_t));
- memcpy(&context.context, uc, sizeof(struct ucontext));
- #if !defined(__ARM_EABI__)
- // FP state is not part of user ABI on ARM Linux.
- struct ucontext *uc_ptr = (struct ucontext*)uc;
- if (uc_ptr->uc_mcontext.fpregs) {
- memcpy(&context.float_state,
- uc_ptr->uc_mcontext.fpregs,
- sizeof(context.float_state));
- }
- #endif
- context.tid = syscall(__NR_gettid);
- if (crash_handler_ != NULL) {
- if (crash_handler_(&context, sizeof(context),
- callback_context_)) {
- return true;
- }
- }
- return GenerateDump(&context);
- }
- // This function may run in a compromised context: see the top of the file.
- bool ExceptionHandler::GenerateDump(CrashContext *context) {
- if (IsOutOfProcess())
- return crash_generation_client_->RequestDump(context, sizeof(*context));
- static const unsigned kChildStackSize = 8000;
- PageAllocator allocator;
- uint8_t* stack = (uint8_t*) allocator.Alloc(kChildStackSize);
- if (!stack)
- return false;
- // clone() needs the top-most address. (scrub just to be safe)
- stack += kChildStackSize;
- my_memset(stack - 16, 0, 16);
- ThreadArgument thread_arg;
- thread_arg.handler = this;
- thread_arg.pid = getpid();
- thread_arg.context = context;
- thread_arg.context_size = sizeof(*context);
- // We need to explicitly enable ptrace of parent processes on some
- // kernels, but we need to know the PID of the cloned process before we
- // can do this. Create a pipe here which we can use to block the
- // cloned process after creating it, until we have explicitly enabled ptrace
- if(sys_pipe(fdes) == -1) {
- // Creating the pipe failed. We'll log an error but carry on anyway,
- // as we'll probably still get a useful crash report. All that will happen
- // is the write() and read() calls will fail with EBADF
- static const char no_pipe_msg[] = "ExceptionHandler::GenerateDump \
- sys_pipe failed:";
- logger::write(no_pipe_msg, sizeof(no_pipe_msg) - 1);
- logger::write(strerror(errno), strlen(strerror(errno)));
- logger::write("\n", 1);
- }
- #if defined(__ANDROID__)
- const pid_t child = clone(
- ThreadEntry, stack, CLONE_FILES | CLONE_FS | CLONE_UNTRACED,
- &thread_arg);
- #else
- const pid_t child = sys_clone(
- ThreadEntry, stack, CLONE_FILES | CLONE_FS | CLONE_UNTRACED,
- &thread_arg, NULL, NULL, NULL);
- #endif
- int r, status;
- // Allow the child to ptrace us
- sys_prctl(PR_SET_PTRACER, child);
- SendContinueSignalToChild();
- do {
- r = sys_waitpid(child, &status, __WALL);
- } while (r == -1 && errno == EINTR);
- sys_close(fdes[0]);
- sys_close(fdes[1]);
- if (r == -1) {
- static const char msg[] = "ExceptionHandler::GenerateDump waitpid failed:";
- logger::write(msg, sizeof(msg) - 1);
- logger::write(strerror(errno), strlen(strerror(errno)));
- logger::write("\n", 1);
- }
- bool success = r != -1 && WIFEXITED(status) && WEXITSTATUS(status) == 0;
- if (callback_)
- success = callback_(dump_path_c_, next_minidump_id_c_,
- callback_context_, success);
- return success;
- }
- // This function runs in a compromised context: see the top of the file.
- void ExceptionHandler::SendContinueSignalToChild() {
- static const char okToContinueMessage = 'a';
- int r;
- r = HANDLE_EINTR(sys_write(fdes[1], &okToContinueMessage, sizeof(char)));
- if(r == -1) {
- static const char msg[] = "ExceptionHandler::SendContinueSignalToChild \
- sys_write failed:";
- logger::write(msg, sizeof(msg) - 1);
- logger::write(strerror(errno), strlen(strerror(errno)));
- logger::write("\n", 1);
- }
- }
- // This function runs in a compromised context: see the top of the file.
- // Runs on the cloned process.
- void ExceptionHandler::WaitForContinueSignal() {
- int r;
- char receivedMessage;
- r = HANDLE_EINTR(sys_read(fdes[0], &receivedMessage, sizeof(char)));
- if(r == -1) {
- static const char msg[] = "ExceptionHandler::WaitForContinueSignal \
- sys_read failed:";
- logger::write(msg, sizeof(msg) - 1);
- logger::write(strerror(errno), strlen(strerror(errno)));
- logger::write("\n", 1);
- }
- }
- // This function runs in a compromised context: see the top of the file.
- // Runs on the cloned process.
- bool ExceptionHandler::DoDump(pid_t crashing_process, const void* context,
- size_t context_size) {
- return google_breakpad::WriteMinidump(next_minidump_path_c_,
- crashing_process,
- context,
- context_size,
- mapping_list_);
- }
- // static
- bool ExceptionHandler::WriteMinidump(const std::string &dump_path,
- MinidumpCallback callback,
- void* callback_context) {
- ExceptionHandler eh(dump_path, NULL, callback, callback_context, false);
- return eh.WriteMinidump();
- }
- bool ExceptionHandler::WriteMinidump() {
- #if !defined(__ARM_EABI__)
- // Allow ourselves to be dumped.
- sys_prctl(PR_SET_DUMPABLE, 1);
- CrashContext context;
- int getcontext_result = getcontext(&context.context);
- if (getcontext_result)
- return false;
- memcpy(&context.float_state, context.context.uc_mcontext.fpregs,
- sizeof(context.float_state));
- context.tid = sys_gettid();
- bool success = GenerateDump(&context);
- UpdateNextID();
- return success;
- #else
- return false;
- #endif // !defined(__ARM_EABI__)
- }
- void ExceptionHandler::AddMappingInfo(const std::string& name,
- const u_int8_t identifier[sizeof(MDGUID)],
- uintptr_t start_address,
- size_t mapping_size,
- size_t file_offset) {
- MappingInfo info;
- info.start_addr = start_address;
- info.size = mapping_size;
- info.offset = file_offset;
- strncpy(info.name, name.c_str(), sizeof(info.name) - 1);
- info.name[sizeof(info.name) - 1] = '\0';
- MappingEntry mapping;
- mapping.first = info;
- memcpy(mapping.second, identifier, sizeof(MDGUID));
- mapping_list_.push_back(mapping);
- }
- } // namespace google_breakpad