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/*
* 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 <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <array>
#include <deque>
#include <string>
#include <unordered_map>
#include <utility>
#include <event2/event.h>
#include <event2/listener.h>
#include <event2/thread.h>
#include <android-base/cmsg.h>
#include <android-base/logging.h>
#include <android-base/properties.h>
#include <android-base/stringprintf.h>
#include <android-base/unique_fd.h>
#include <cutils/sockets.h>
#include "debuggerd/handler.h"
#include "dump_type.h"
#include "protocol.h"
#include "util.h"
#include "intercept_manager.h"
using android::base::GetIntProperty;
using android::base::SendFileDescriptors;
using android::base::StringPrintf;
using android::base::unique_fd;
static InterceptManager* intercept_manager;
enum CrashStatus {
kCrashStatusRunning,
kCrashStatusQueued,
};
// Ownership of Crash is a bit messy.
// It's either owned by an active event that must have a timeout, or owned by
// queued_requests, in the case that multiple crashes come in at the same time.
struct Crash {
~Crash() { event_free(crash_event); }
std::string crash_tombstone_path;
unique_fd crash_tombstone_fd;
unique_fd crash_socket_fd;
pid_t crash_pid;
event* crash_event = nullptr;
DebuggerdDumpType crash_type;
};
class CrashQueue {
public:
CrashQueue(const std::string& dir_path, const std::string& file_name_prefix, size_t max_artifacts,
size_t max_concurrent_dumps)
: file_name_prefix_(file_name_prefix),
dir_path_(dir_path),
dir_fd_(open(dir_path.c_str(), O_DIRECTORY | O_RDONLY | O_CLOEXEC)),
max_artifacts_(max_artifacts),
next_artifact_(0),
max_concurrent_dumps_(max_concurrent_dumps),
num_concurrent_dumps_(0) {
if (dir_fd_ == -1) {
PLOG(FATAL) << "failed to open directory: " << dir_path;
}
// NOTE: If max_artifacts_ <= max_concurrent_dumps_, then theoretically the
// same filename could be handed out to multiple processes.
CHECK(max_artifacts_ > max_concurrent_dumps_);
find_oldest_artifact();
}
static CrashQueue* for_crash(const Crash* crash) {
return (crash->crash_type == kDebuggerdJavaBacktrace) ? for_anrs() : for_tombstones();
}
static CrashQueue* for_tombstones() {
static CrashQueue queue("/data/tombstones", "tombstone_" /* file_name_prefix */,
GetIntProperty("tombstoned.max_tombstone_count", 32),
1 /* max_concurrent_dumps */);
return &queue;
}
static CrashQueue* for_anrs() {
static CrashQueue queue("/data/anr", "trace_" /* file_name_prefix */,
GetIntProperty("tombstoned.max_anr_count", 64),
4 /* max_concurrent_dumps */);
return &queue;
}
std::pair<std::string, unique_fd> get_output() {
std::string path;
unique_fd result(openat(dir_fd_, ".", O_WRONLY | O_APPEND | O_TMPFILE | O_CLOEXEC, 0640));
if (result == -1) {
// We might not have O_TMPFILE. Try creating with an arbitrary filename instead.
static size_t counter = 0;
std::string tmp_filename = StringPrintf(".temporary%zu", counter++);
result.reset(openat(dir_fd_, tmp_filename.c_str(),
O_WRONLY | O_APPEND | O_CREAT | O_TRUNC | O_CLOEXEC, 0640));
if (result == -1) {
PLOG(FATAL) << "failed to create temporary tombstone in " << dir_path_;
}
path = StringPrintf("%s/%s", dir_path_.c_str(), tmp_filename.c_str());
}
return std::make_pair(std::move(path), std::move(result));
}
std::string get_next_artifact_path() {
std::string file_name =
StringPrintf("%s/%s%02d", dir_path_.c_str(), file_name_prefix_.c_str(), next_artifact_);
next_artifact_ = (next_artifact_ + 1) % max_artifacts_;
return file_name;
}
bool maybe_enqueue_crash(Crash* crash) {
if (num_concurrent_dumps_ == max_concurrent_dumps_) {
queued_requests_.push_back(crash);
return true;
}
return false;
}
void maybe_dequeue_crashes(void (*handler)(Crash* crash)) {
while (!queued_requests_.empty() && num_concurrent_dumps_ < max_concurrent_dumps_) {
Crash* next_crash = queued_requests_.front();
queued_requests_.pop_front();
handler(next_crash);
}
}
void on_crash_started() { ++num_concurrent_dumps_; }
void on_crash_completed() { --num_concurrent_dumps_; }
private:
void find_oldest_artifact() {
size_t oldest_tombstone = 0;
time_t oldest_time = std::numeric_limits<time_t>::max();
for (size_t i = 0; i < max_artifacts_; ++i) {
std::string path = StringPrintf("%s/%s%02zu", dir_path_.c_str(), file_name_prefix_.c_str(), i);
struct stat st;
if (stat(path.c_str(), &st) != 0) {
if (errno == ENOENT) {
oldest_tombstone = i;
break;
} else {
PLOG(ERROR) << "failed to stat " << path;
continue;
}
}
if (st.st_mtime < oldest_time) {
oldest_tombstone = i;
oldest_time = st.st_mtime;
}
}
next_artifact_ = oldest_tombstone;
}
const std::string file_name_prefix_;
const std::string dir_path_;
const int dir_fd_;
const size_t max_artifacts_;
int next_artifact_;
const size_t max_concurrent_dumps_;
size_t num_concurrent_dumps_;
std::deque<Crash*> queued_requests_;
DISALLOW_COPY_AND_ASSIGN(CrashQueue);
};
// Whether java trace dumps are produced via tombstoned.
static constexpr bool kJavaTraceDumpsEnabled = true;
// Forward declare the callbacks so they can be placed in a sensible order.
static void crash_accept_cb(evconnlistener* listener, evutil_socket_t sockfd, sockaddr*, int, void*);
static void crash_request_cb(evutil_socket_t sockfd, short ev, void* arg);
static void crash_completed_cb(evutil_socket_t sockfd, short ev, void* arg);
static void perform_request(Crash* crash) {
unique_fd output_fd;
bool intercepted =
intercept_manager->GetIntercept(crash->crash_pid, crash->crash_type, &output_fd);
if (!intercepted) {
if (crash->crash_type == kDebuggerdNativeBacktrace) {
// Don't generate tombstones for native backtrace requests.
output_fd.reset(open("/dev/null", O_WRONLY | O_CLOEXEC));
} else {
std::tie(crash->crash_tombstone_path, output_fd) = CrashQueue::for_crash(crash)->get_output();
crash->crash_tombstone_fd.reset(dup(output_fd.get()));
}
}
TombstonedCrashPacket response = {
.packet_type = CrashPacketType::kPerformDump
};
ssize_t rc =
SendFileDescriptors(crash->crash_socket_fd, &response, sizeof(response), output_fd.get());
output_fd.reset();
if (rc == -1) {
PLOG(WARNING) << "failed to send response to CrashRequest";
goto fail;
} else if (rc != sizeof(response)) {
PLOG(WARNING) << "crash socket write returned short";
goto fail;
} else {
// TODO: Make this configurable by the interceptor?
struct timeval timeout = { 10, 0 };
event_base* base = event_get_base(crash->crash_event);
event_assign(crash->crash_event, base, crash->crash_socket_fd, EV_TIMEOUT | EV_READ,
crash_completed_cb, crash);
event_add(crash->crash_event, &timeout);
}
CrashQueue::for_crash(crash)->on_crash_started();
return;
fail:
delete crash;
}
static void crash_accept_cb(evconnlistener* listener, evutil_socket_t sockfd, sockaddr*, int,
void*) {
event_base* base = evconnlistener_get_base(listener);
Crash* crash = new Crash();
// TODO: Make sure that only java crashes come in on the java socket
// and only native crashes on the native socket.
struct timeval timeout = { 1, 0 };
event* crash_event = event_new(base, sockfd, EV_TIMEOUT | EV_READ, crash_request_cb, crash);
crash->crash_socket_fd.reset(sockfd);
crash->crash_event = crash_event;
event_add(crash_event, &timeout);
}
static void crash_request_cb(evutil_socket_t sockfd, short ev, void* arg) {
ssize_t rc;
Crash* crash = static_cast<Crash*>(arg);
TombstonedCrashPacket request = {};
if ((ev & EV_TIMEOUT) != 0) {
LOG(WARNING) << "crash request timed out";
goto fail;
} else if ((ev & EV_READ) == 0) {
LOG(WARNING) << "tombstoned received unexpected event from crash socket";
goto fail;
}
rc = TEMP_FAILURE_RETRY(read(sockfd, &request, sizeof(request)));
if (rc == -1) {
PLOG(WARNING) << "failed to read from crash socket";
goto fail;
} else if (rc != sizeof(request)) {
LOG(WARNING) << "crash socket received short read of length " << rc << " (expected "
<< sizeof(request) << ")";
goto fail;
}
if (request.packet_type != CrashPacketType::kDumpRequest) {
LOG(WARNING) << "unexpected crash packet type, expected kDumpRequest, received "
<< StringPrintf("%#2hhX", request.packet_type);
goto fail;
}
crash->crash_type = request.packet.dump_request.dump_type;
if (crash->crash_type < 0 || crash->crash_type > kDebuggerdAnyIntercept) {
LOG(WARNING) << "unexpected crash dump type: " << crash->crash_type;
goto fail;
}
if (crash->crash_type != kDebuggerdJavaBacktrace) {
crash->crash_pid = request.packet.dump_request.pid;
} else {
// Requests for java traces are sent from untrusted processes, so we
// must not trust the PID sent down with the request. Instead, we ask the
// kernel.
ucred cr = {};
socklen_t len = sizeof(cr);
int ret = getsockopt(sockfd, SOL_SOCKET, SO_PEERCRED, &cr, &len);
if (ret != 0) {
PLOG(ERROR) << "Failed to getsockopt(..SO_PEERCRED)";
goto fail;
}
crash->crash_pid = cr.pid;
}
LOG(INFO) << "received crash request for pid " << crash->crash_pid;
if (CrashQueue::for_crash(crash)->maybe_enqueue_crash(crash)) {
LOG(INFO) << "enqueueing crash request for pid " << crash->crash_pid;
} else {
perform_request(crash);
}
return;
fail:
delete crash;
}
static void crash_completed_cb(evutil_socket_t sockfd, short ev, void* arg) {
ssize_t rc;
Crash* crash = static_cast<Crash*>(arg);
TombstonedCrashPacket request = {};
CrashQueue::for_crash(crash)->on_crash_completed();
if ((ev & EV_READ) == 0) {
goto fail;
}
rc = TEMP_FAILURE_RETRY(read(sockfd, &request, sizeof(request)));
if (rc == -1) {
PLOG(WARNING) << "failed to read from crash socket";
goto fail;
} else if (rc != sizeof(request)) {
LOG(WARNING) << "crash socket received short read of length " << rc << " (expected "
<< sizeof(request) << ")";
goto fail;
}
if (request.packet_type != CrashPacketType::kCompletedDump) {
LOG(WARNING) << "unexpected crash packet type, expected kCompletedDump, received "
<< uint32_t(request.packet_type);
goto fail;
}
if (crash->crash_tombstone_fd != -1) {
std::string fd_path = StringPrintf("/proc/self/fd/%d", crash->crash_tombstone_fd.get());
std::string tombstone_path = CrashQueue::for_crash(crash)->get_next_artifact_path();
// linkat doesn't let us replace a file, so we need to unlink first.
int rc = unlink(tombstone_path.c_str());
if (rc != 0 && errno != ENOENT) {
PLOG(ERROR) << "failed to unlink tombstone at " << tombstone_path;
goto fail;
}
rc = linkat(AT_FDCWD, fd_path.c_str(), AT_FDCWD, tombstone_path.c_str(), AT_SYMLINK_FOLLOW);
if (rc != 0) {
PLOG(ERROR) << "failed to link tombstone";
} else {
if (crash->crash_type == kDebuggerdJavaBacktrace) {
LOG(ERROR) << "Traces for pid " << crash->crash_pid << " written to: " << tombstone_path;
} else {
// NOTE: Several tools parse this log message to figure out where the
// tombstone associated with a given native crash was written. Any changes
// to this message must be carefully considered.
LOG(ERROR) << "Tombstone written to: " << tombstone_path;
}
}
// If we don't have O_TMPFILE, we need to clean up after ourselves.
if (!crash->crash_tombstone_path.empty()) {
rc = unlink(crash->crash_tombstone_path.c_str());
if (rc != 0) {
PLOG(ERROR) << "failed to unlink temporary tombstone at " << crash->crash_tombstone_path;
}
}
}
fail:
CrashQueue* queue = CrashQueue::for_crash(crash);
delete crash;
// If there's something queued up, let them proceed.
queue->maybe_dequeue_crashes(perform_request);
}
int main(int, char* []) {
umask(0137);
// Don't try to connect to ourselves if we crash.
struct sigaction action = {};
action.sa_handler = [](int signal) {
LOG(ERROR) << "received fatal signal " << signal;
_exit(1);
};
debuggerd_register_handlers(&action);
int intercept_socket = android_get_control_socket(kTombstonedInterceptSocketName);
int crash_socket = android_get_control_socket(kTombstonedCrashSocketName);
if (intercept_socket == -1 || crash_socket == -1) {
PLOG(FATAL) << "failed to get socket from init";
}
evutil_make_socket_nonblocking(intercept_socket);
evutil_make_socket_nonblocking(crash_socket);
event_base* base = event_base_new();
if (!base) {
LOG(FATAL) << "failed to create event_base";
}
intercept_manager = new InterceptManager(base, intercept_socket);
evconnlistener* tombstone_listener =
evconnlistener_new(base, crash_accept_cb, CrashQueue::for_tombstones(), LEV_OPT_CLOSE_ON_FREE,
-1 /* backlog */, crash_socket);
if (!tombstone_listener) {
LOG(FATAL) << "failed to create evconnlistener for tombstones.";
}
if (kJavaTraceDumpsEnabled) {
const int java_trace_socket = android_get_control_socket(kTombstonedJavaTraceSocketName);
if (java_trace_socket == -1) {
PLOG(FATAL) << "failed to get socket from init";
}
evutil_make_socket_nonblocking(java_trace_socket);
evconnlistener* java_trace_listener =
evconnlistener_new(base, crash_accept_cb, CrashQueue::for_anrs(), LEV_OPT_CLOSE_ON_FREE,
-1 /* backlog */, java_trace_socket);
if (!java_trace_listener) {
LOG(FATAL) << "failed to create evconnlistener for java traces.";
}
}
LOG(INFO) << "tombstoned successfully initialized";
event_base_dispatch(base);
}