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Clementine-audio-player-Mac.../3rdparty/google-breakpad/client/linux/handler/exception_handler.cc

513 lines
18 KiB
C++

// 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>
#if !defined(__ANDROID__)
#include <sys/signal.h>
#endif
#include <sys/syscall.h>
#if !defined(__ANDROID__)
#include <sys/ucontext.h>
#include <sys/user.h>
#endif
#include <sys/wait.h>
#if !defined(__ANDROID__)
#include <ucontext.h>
#endif
#include <unistd.h>
#include <algorithm>
#include <utility>
#include <vector>
#include "common/linux/linux_libc_support.h"
#include "common/memory.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"
#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;
signal_stack = malloc(kSigStackSize);
stack_t stack;
memset(&stack, 0, sizeof(stack));
stack.ss_sp = signal_stack;
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:";
sys_write(2, no_pipe_msg, sizeof(no_pipe_msg) - 1);
sys_write(2, strerror(errno), strlen(strerror(errno)));
sys_write(2, "\n", 1);
}
const pid_t child = sys_clone(
ThreadEntry, stack, CLONE_FILES | CLONE_FS | CLONE_UNTRACED,
&thread_arg, NULL, NULL, NULL);
int r, status;
// Allow the child to ptrace us
prctl(PR_SET_PTRACER, child, 0, 0, 0);
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:";
sys_write(2, msg, sizeof(msg) - 1);
sys_write(2, strerror(errno), strlen(strerror(errno)));
sys_write(2, "\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:";
sys_write(2, msg, sizeof(msg) - 1);
sys_write(2, strerror(errno), strlen(strerror(errno)));
sys_write(2, "\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:";
sys_write(2, msg, sizeof(msg) - 1);
sys_write(2, strerror(errno), strlen(strerror(errno)));
sys_write(2, "\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(), std::min(name.size(), sizeof(info)));
MappingEntry mapping;
mapping.first = info;
memcpy(mapping.second, identifier, sizeof(MDGUID));
mapping_list_.push_back(mapping);
}
} // namespace google_breakpad