1 // Copyright 2013 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #include "components/crash/browser/crash_handler_host_linux.h" 6 7 #include <stdint.h> 8 #include <stdlib.h> 9 #include <sys/socket.h> 10 #include <sys/syscall.h> 11 #include <unistd.h> 12 13 #include "base/bind.h" 14 #include "base/bind_helpers.h" 15 #include "base/files/file_path.h" 16 #include "base/files/file_util.h" 17 #include "base/files/scoped_file.h" 18 #include "base/format_macros.h" 19 #include "base/linux_util.h" 20 #include "base/logging.h" 21 #include "base/message_loop/message_loop.h" 22 #include "base/path_service.h" 23 #include "base/posix/eintr_wrapper.h" 24 #include "base/rand_util.h" 25 #include "base/strings/string_util.h" 26 #include "base/strings/stringprintf.h" 27 #include "base/threading/thread.h" 28 #include "breakpad/src/client/linux/handler/exception_handler.h" 29 #include "breakpad/src/client/linux/minidump_writer/linux_dumper.h" 30 #include "breakpad/src/client/linux/minidump_writer/minidump_writer.h" 31 #include "components/crash/app/breakpad_linux_impl.h" 32 #include "content/public/browser/browser_thread.h" 33 34 #if defined(OS_ANDROID) && !defined(__LP64__) 35 #include <sys/linux-syscalls.h> 36 37 #define SYS_read __NR_read 38 #endif 39 40 using content::BrowserThread; 41 using google_breakpad::ExceptionHandler; 42 43 namespace breakpad { 44 45 namespace { 46 47 const size_t kNumFDs = 1; 48 // The length of the control message: 49 const size_t kControlMsgSize = 50 CMSG_SPACE(kNumFDs * sizeof(int)) + CMSG_SPACE(sizeof(struct ucred)); 51 // The length of the regular payload: 52 const size_t kCrashContextSize = sizeof(ExceptionHandler::CrashContext); 53 54 // Handles the crash dump and frees the allocated BreakpadInfo struct. 55 void CrashDumpTask(CrashHandlerHostLinux* handler, 56 scoped_ptr<BreakpadInfo> info) { 57 if (handler->IsShuttingDown() && info->upload) { 58 base::DeleteFile(base::FilePath(info->filename), false); 59 #if defined(ADDRESS_SANITIZER) 60 base::DeleteFile(base::FilePath(info->log_filename), false); 61 #endif 62 return; 63 } 64 65 HandleCrashDump(*info); 66 delete[] info->filename; 67 #if defined(ADDRESS_SANITIZER) 68 delete[] info->log_filename; 69 delete[] info->asan_report_str; 70 #endif 71 delete[] info->process_type; 72 delete[] info->distro; 73 delete info->crash_keys; 74 } 75 76 } // namespace 77 78 // Since instances of CrashHandlerHostLinux are leaked, they are only destroyed 79 // at the end of the processes lifetime, which is greater in span than the 80 // lifetime of the IO message loop. Thus, all calls to base::Bind() use 81 // non-refcounted pointers. 82 83 CrashHandlerHostLinux::CrashHandlerHostLinux(const std::string& process_type, 84 const base::FilePath& dumps_path, 85 bool upload) 86 : process_type_(process_type), 87 dumps_path_(dumps_path), 88 upload_(upload), 89 shutting_down_(false), 90 worker_pool_token_(BrowserThread::GetBlockingPool()->GetSequenceToken()) { 91 int fds[2]; 92 // We use SOCK_SEQPACKET rather than SOCK_DGRAM to prevent the process from 93 // sending datagrams to other sockets on the system. The sandbox may prevent 94 // the process from calling socket() to create new sockets, but it'll still 95 // inherit some sockets. With PF_UNIX+SOCK_DGRAM, it can call sendmsg to send 96 // a datagram to any (abstract) socket on the same system. With 97 // SOCK_SEQPACKET, this is prevented. 98 CHECK_EQ(0, socketpair(AF_UNIX, SOCK_SEQPACKET, 0, fds)); 99 static const int on = 1; 100 101 // Enable passcred on the server end of the socket 102 CHECK_EQ(0, setsockopt(fds[1], SOL_SOCKET, SO_PASSCRED, &on, sizeof(on))); 103 104 process_socket_ = fds[0]; 105 browser_socket_ = fds[1]; 106 107 BrowserThread::PostTask( 108 BrowserThread::IO, FROM_HERE, 109 base::Bind(&CrashHandlerHostLinux::Init, base::Unretained(this))); 110 } 111 112 CrashHandlerHostLinux::~CrashHandlerHostLinux() { 113 close(process_socket_); 114 close(browser_socket_); 115 } 116 117 void CrashHandlerHostLinux::StartUploaderThread() { 118 uploader_thread_.reset( 119 new base::Thread(process_type_ + "_crash_uploader")); 120 uploader_thread_->Start(); 121 } 122 123 void CrashHandlerHostLinux::Init() { 124 base::MessageLoopForIO* ml = base::MessageLoopForIO::current(); 125 CHECK(ml->WatchFileDescriptor( 126 browser_socket_, true /* persistent */, 127 base::MessageLoopForIO::WATCH_READ, 128 &file_descriptor_watcher_, this)); 129 ml->AddDestructionObserver(this); 130 } 131 132 void CrashHandlerHostLinux::OnFileCanWriteWithoutBlocking(int fd) { 133 NOTREACHED(); 134 } 135 136 void CrashHandlerHostLinux::OnFileCanReadWithoutBlocking(int fd) { 137 DCHECK_EQ(browser_socket_, fd); 138 139 // A process has crashed and has signaled us by writing a datagram 140 // to the death signal socket. The datagram contains the crash context needed 141 // for writing the minidump as well as a file descriptor and a credentials 142 // block so that they can't lie about their pid. 143 // 144 // The message sender is in components/crash/app/breakpad_linux.cc. 145 146 struct msghdr msg = {0}; 147 struct iovec iov[kCrashIovSize]; 148 149 scoped_ptr<char[]> crash_context(new char[kCrashContextSize]); 150 #if defined(ADDRESS_SANITIZER) 151 scoped_ptr<char[]> asan_report(new char[kMaxAsanReportSize + 1]); 152 #endif 153 154 scoped_ptr<CrashKeyStorage> crash_keys(new CrashKeyStorage); 155 google_breakpad::SerializedNonAllocatingMap* serialized_crash_keys; 156 size_t crash_keys_size = crash_keys->Serialize( 157 const_cast<const google_breakpad::SerializedNonAllocatingMap**>( 158 &serialized_crash_keys)); 159 160 char* tid_buf_addr = NULL; 161 int tid_fd = -1; 162 uint64_t uptime; 163 size_t oom_size; 164 char control[kControlMsgSize]; 165 const ssize_t expected_msg_size = 166 kCrashContextSize + 167 sizeof(tid_buf_addr) + sizeof(tid_fd) + 168 sizeof(uptime) + 169 #if defined(ADDRESS_SANITIZER) 170 kMaxAsanReportSize + 1 + 171 #endif 172 sizeof(oom_size) + 173 crash_keys_size; 174 iov[0].iov_base = crash_context.get(); 175 iov[0].iov_len = kCrashContextSize; 176 iov[1].iov_base = &tid_buf_addr; 177 iov[1].iov_len = sizeof(tid_buf_addr); 178 iov[2].iov_base = &tid_fd; 179 iov[2].iov_len = sizeof(tid_fd); 180 iov[3].iov_base = &uptime; 181 iov[3].iov_len = sizeof(uptime); 182 iov[4].iov_base = &oom_size; 183 iov[4].iov_len = sizeof(oom_size); 184 iov[5].iov_base = serialized_crash_keys; 185 iov[5].iov_len = crash_keys_size; 186 #if !defined(ADDRESS_SANITIZER) 187 COMPILE_ASSERT(5 == kCrashIovSize - 1, Incorrect_Number_Of_Iovec_Members); 188 #else 189 iov[6].iov_base = asan_report.get(); 190 iov[6].iov_len = kMaxAsanReportSize + 1; 191 COMPILE_ASSERT(6 == kCrashIovSize - 1, Incorrect_Number_Of_Iovec_Members); 192 #endif 193 msg.msg_iov = iov; 194 msg.msg_iovlen = kCrashIovSize; 195 msg.msg_control = control; 196 msg.msg_controllen = kControlMsgSize; 197 198 const ssize_t msg_size = HANDLE_EINTR(recvmsg(browser_socket_, &msg, 0)); 199 if (msg_size < 0) { 200 LOG(ERROR) << "Error reading from death signal socket. Crash dumping" 201 << " is disabled." 202 << " msg_size:" << msg_size 203 << " errno:" << errno; 204 file_descriptor_watcher_.StopWatchingFileDescriptor(); 205 return; 206 } 207 const bool bad_message = (msg_size != expected_msg_size || 208 msg.msg_controllen != kControlMsgSize || 209 msg.msg_flags & ~MSG_TRUNC); 210 base::ScopedFD signal_fd; 211 pid_t crashing_pid = -1; 212 if (msg.msg_controllen > 0) { 213 // Walk the control payload and extract the file descriptor and 214 // validated pid. 215 for (struct cmsghdr *hdr = CMSG_FIRSTHDR(&msg); hdr; 216 hdr = CMSG_NXTHDR(&msg, hdr)) { 217 if (hdr->cmsg_level != SOL_SOCKET) 218 continue; 219 if (hdr->cmsg_type == SCM_RIGHTS) { 220 const size_t len = hdr->cmsg_len - 221 (((uint8_t*)CMSG_DATA(hdr)) - (uint8_t*)hdr); 222 DCHECK_EQ(0U, len % sizeof(int)); 223 const size_t num_fds = len / sizeof(int); 224 if (num_fds != kNumFDs) { 225 // A nasty process could try and send us too many descriptors and 226 // force a leak. 227 LOG(ERROR) << "Death signal contained wrong number of descriptors;" 228 << " num_fds:" << num_fds; 229 for (size_t i = 0; i < num_fds; ++i) 230 close(reinterpret_cast<int*>(CMSG_DATA(hdr))[i]); 231 return; 232 } 233 DCHECK(!signal_fd.is_valid()); 234 int fd = reinterpret_cast<int*>(CMSG_DATA(hdr))[0]; 235 DCHECK_GE(fd, 0); // The kernel should never send a negative fd. 236 signal_fd.reset(fd); 237 } else if (hdr->cmsg_type == SCM_CREDENTIALS) { 238 DCHECK_EQ(-1, crashing_pid); 239 const struct ucred *cred = 240 reinterpret_cast<struct ucred*>(CMSG_DATA(hdr)); 241 crashing_pid = cred->pid; 242 } 243 } 244 } 245 246 if (bad_message) { 247 LOG(ERROR) << "Received death signal message with the wrong size;" 248 << " msg.msg_controllen:" << msg.msg_controllen 249 << " msg.msg_flags:" << msg.msg_flags 250 << " kCrashContextSize:" << kCrashContextSize 251 << " kControlMsgSize:" << kControlMsgSize; 252 return; 253 } 254 if (crashing_pid == -1 || !signal_fd.is_valid()) { 255 LOG(ERROR) << "Death signal message didn't contain all expected control" 256 << " messages"; 257 return; 258 } 259 260 // The crashing TID set inside the compromised context via 261 // sys_gettid() in ExceptionHandler::HandleSignal might be wrong (if 262 // the kernel supports PID namespacing) and may need to be 263 // translated. 264 // 265 // We expect the crashing thread to be in sys_read(), waiting for us to 266 // write to |signal_fd|. Most newer kernels where we have the different pid 267 // namespaces also have /proc/[pid]/syscall, so we can look through 268 // |actual_crashing_pid|'s thread group and find the thread that's in the 269 // read syscall with the right arguments. 270 271 std::string expected_syscall_data; 272 // /proc/[pid]/syscall is formatted as follows: 273 // syscall_number arg1 ... arg6 sp pc 274 // but we just check syscall_number through arg3. 275 base::StringAppendF(&expected_syscall_data, "%d 0x%x %p 0x1 ", 276 SYS_read, tid_fd, tid_buf_addr); 277 bool syscall_supported = false; 278 pid_t crashing_tid = 279 base::FindThreadIDWithSyscall(crashing_pid, 280 expected_syscall_data, 281 &syscall_supported); 282 if (crashing_tid == -1) { 283 // We didn't find the thread we want. Maybe it didn't reach 284 // sys_read() yet or the thread went away. We'll just take a 285 // guess here and assume the crashing thread is the thread group 286 // leader. If procfs syscall is not supported by the kernel, then 287 // we assume the kernel also does not support TID namespacing and 288 // trust the TID passed by the crashing process. 289 LOG(WARNING) << "Could not translate tid - assuming crashing thread is " 290 "thread group leader; syscall_supported=" << syscall_supported; 291 crashing_tid = crashing_pid; 292 } 293 294 ExceptionHandler::CrashContext* bad_context = 295 reinterpret_cast<ExceptionHandler::CrashContext*>(crash_context.get()); 296 bad_context->tid = crashing_tid; 297 298 scoped_ptr<BreakpadInfo> info(new BreakpadInfo); 299 300 info->fd = -1; 301 info->process_type_length = process_type_.length(); 302 // Freed in CrashDumpTask(). 303 char* process_type_str = new char[info->process_type_length + 1]; 304 process_type_.copy(process_type_str, info->process_type_length); 305 process_type_str[info->process_type_length] = '\0'; 306 info->process_type = process_type_str; 307 308 // Memory released from scoped_ptrs below are also freed in CrashDumpTask(). 309 info->crash_keys = crash_keys.release(); 310 #if defined(ADDRESS_SANITIZER) 311 asan_report[kMaxAsanReportSize] = '\0'; 312 info->asan_report_str = asan_report.release(); 313 info->asan_report_length = strlen(info->asan_report_str); 314 #endif 315 316 info->process_start_time = uptime; 317 info->oom_size = oom_size; 318 #if defined(OS_ANDROID) 319 // Nothing gets uploaded in android. 320 info->upload = false; 321 #else 322 info->upload = upload_; 323 #endif 324 325 326 BrowserThread::GetBlockingPool()->PostSequencedWorkerTask( 327 worker_pool_token_, 328 FROM_HERE, 329 base::Bind(&CrashHandlerHostLinux::WriteDumpFile, 330 base::Unretained(this), 331 base::Passed(&info), 332 base::Passed(&crash_context), 333 crashing_pid, 334 signal_fd.release())); 335 } 336 337 void CrashHandlerHostLinux::WriteDumpFile(scoped_ptr<BreakpadInfo> info, 338 scoped_ptr<char[]> crash_context, 339 pid_t crashing_pid, 340 int signal_fd) { 341 DCHECK(BrowserThread::GetBlockingPool()->IsRunningSequenceOnCurrentThread( 342 worker_pool_token_)); 343 344 // Set |info->distro| here because base::GetLinuxDistro() needs to run on a 345 // blocking thread. 346 std::string distro = base::GetLinuxDistro(); 347 info->distro_length = distro.length(); 348 // Freed in CrashDumpTask(). 349 char* distro_str = new char[info->distro_length + 1]; 350 distro.copy(distro_str, info->distro_length); 351 distro_str[info->distro_length] = '\0'; 352 info->distro = distro_str; 353 354 base::FilePath dumps_path("/tmp"); 355 PathService::Get(base::DIR_TEMP, &dumps_path); 356 if (!info->upload) 357 dumps_path = dumps_path_; 358 const std::string minidump_filename = 359 base::StringPrintf("%s/chromium-%s-minidump-%016" PRIx64 ".dmp", 360 dumps_path.value().c_str(), 361 process_type_.c_str(), 362 base::RandUint64()); 363 364 if (!google_breakpad::WriteMinidump(minidump_filename.c_str(), 365 kMaxMinidumpFileSize, 366 crashing_pid, 367 crash_context.get(), 368 kCrashContextSize, 369 google_breakpad::MappingList(), 370 google_breakpad::AppMemoryList())) { 371 LOG(ERROR) << "Failed to write crash dump for pid " << crashing_pid; 372 } 373 #if defined(ADDRESS_SANITIZER) 374 // Create a temporary file holding the AddressSanitizer report. 375 const base::FilePath log_path = 376 base::FilePath(minidump_filename).ReplaceExtension("log"); 377 base::WriteFile(log_path, info->asan_report_str, info->asan_report_length); 378 #endif 379 380 // Freed in CrashDumpTask(). 381 char* minidump_filename_str = new char[minidump_filename.length() + 1]; 382 minidump_filename.copy(minidump_filename_str, minidump_filename.length()); 383 minidump_filename_str[minidump_filename.length()] = '\0'; 384 info->filename = minidump_filename_str; 385 #if defined(ADDRESS_SANITIZER) 386 // Freed in CrashDumpTask(). 387 char* minidump_log_filename_str = new char[minidump_filename.length() + 1]; 388 minidump_filename.copy(minidump_log_filename_str, minidump_filename.length()); 389 memcpy(minidump_log_filename_str + minidump_filename.length() - 3, "log", 3); 390 minidump_log_filename_str[minidump_filename.length()] = '\0'; 391 info->log_filename = minidump_log_filename_str; 392 #endif 393 info->pid = crashing_pid; 394 395 BrowserThread::PostTask( 396 BrowserThread::IO, FROM_HERE, 397 base::Bind(&CrashHandlerHostLinux::QueueCrashDumpTask, 398 base::Unretained(this), 399 base::Passed(&info), 400 signal_fd)); 401 } 402 403 void CrashHandlerHostLinux::QueueCrashDumpTask(scoped_ptr<BreakpadInfo> info, 404 int signal_fd) { 405 DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO)); 406 407 // Send the done signal to the process: it can exit now. 408 struct msghdr msg = {0}; 409 struct iovec done_iov; 410 done_iov.iov_base = const_cast<char*>("\x42"); 411 done_iov.iov_len = 1; 412 msg.msg_iov = &done_iov; 413 msg.msg_iovlen = 1; 414 415 HANDLE_EINTR(sendmsg(signal_fd, &msg, MSG_DONTWAIT | MSG_NOSIGNAL)); 416 close(signal_fd); 417 418 uploader_thread_->message_loop()->PostTask( 419 FROM_HERE, 420 base::Bind(&CrashDumpTask, base::Unretained(this), base::Passed(&info))); 421 } 422 423 void CrashHandlerHostLinux::WillDestroyCurrentMessageLoop() { 424 file_descriptor_watcher_.StopWatchingFileDescriptor(); 425 426 // If we are quitting and there are crash dumps in the queue, turn them into 427 // no-ops. 428 shutting_down_ = true; 429 uploader_thread_->Stop(); 430 } 431 432 bool CrashHandlerHostLinux::IsShuttingDown() const { 433 return shutting_down_; 434 } 435 436 } // namespace breakpad 437
