ipc/ipc_channel_nacl.cc

   1 // Copyright (c) 2012 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 "ipc/ipc_channel_nacl.h"
   6
   7 #include <errno.h>
   8 #include <stddef.h>
   9 #include <sys/nacl_imc_api.h>
  10 #include <sys/nacl_syscalls.h>
  11 #include <sys/types.h>
  12
  13 #include <algorithm>
  14
  15 #include "base/bind.h"
  16 #include "base/file_util.h"
  17 #include "base/logging.h"
  18 #include "base/message_loop_proxy.h"
  19 #include "base/process_util.h"
  20 #include "base/synchronization/lock.h"
  21 #include "base/task_runner_util.h"
  22 #include "base/threading/simple_thread.h"
  23 #include "ipc/file_descriptor_set_posix.h"
  24 #include "ipc/ipc_logging.h"
  25
  26 namespace IPC {
  27
  28 struct MessageContents {
  29   std::vector<char> data;
  30   std::vector<int> fds;
  31 };
  32
  33 namespace {
  34
  35 bool ReadDataOnReaderThread(int pipe, MessageContents* contents) {
  36   DCHECK(pipe >= 0);
  37   if (pipe < 0)
  38     return false;
  39
  40   contents->data.resize(Channel::kReadBufferSize);
  41   contents->fds.resize(FileDescriptorSet::kMaxDescriptorsPerMessage);
  42
  43   NaClImcMsgIoVec iov = { &contents->data[0], contents->data.size() };
  44   NaClImcMsgHdr msg = { &iov, 1, &contents->fds[0], contents->fds.size() };
  45
  46   int bytes_read = imc_recvmsg(pipe, &msg, 0);
  47
  48   if (bytes_read <= 0) {
  49     // NaClIPCAdapter::BlockingReceive returns -1 when the pipe closes (either
  50     // due to error or for regular shutdown).
  51     contents->data.clear();
  52     contents->fds.clear();
  53     return false;
  54   }
  55   DCHECK(bytes_read);
  56   // Resize the buffers down to the number of bytes and fds we actually read.
  57   contents->data.resize(bytes_read);
  58   contents->fds.resize(msg.desc_length);
  59   return true;
  60 }
  61
  62 }  // namespace
  63
  64 class Channel::ChannelImpl::ReaderThreadRunner
  65     : public base::DelegateSimpleThread::Delegate {
  66  public:
  67   // |pipe|: A file descriptor from which we will read using imc_recvmsg.
  68   // |data_read_callback|: A callback we invoke (on the main thread) when we
  69   //                       have read data.
  70   // |failure_callback|: A callback we invoke when we have a failure reading
  71   //                     from |pipe|.
  72   // |main_message_loop|: A proxy for the main thread, where we will invoke the
  73   //                      above callbacks.
  74   ReaderThreadRunner(
  75       int pipe,
  76       base::Callback<void (scoped_ptr<MessageContents>)> data_read_callback,
  77       base::Callback<void ()> failure_callback,
  78       scoped_refptr<base::MessageLoopProxy> main_message_loop);
  79
  80   // DelegateSimpleThread implementation. Reads data from the pipe in a loop
  81   // until either we are told to quit or a read fails.
  82   virtual void Run() OVERRIDE;
  83
  84  private:
  85   int pipe_;
  86   base::Callback<void (scoped_ptr<MessageContents>)> data_read_callback_;
  87   base::Callback<void ()> failure_callback_;
  88   scoped_refptr<base::MessageLoopProxy> main_message_loop_;
  89
  90   DISALLOW_COPY_AND_ASSIGN(ReaderThreadRunner);
  91 };
  92
  93 Channel::ChannelImpl::ReaderThreadRunner::ReaderThreadRunner(
  94     int pipe,
  95     base::Callback<void (scoped_ptr<MessageContents>)> data_read_callback,
  96     base::Callback<void ()> failure_callback,
  97     scoped_refptr<base::MessageLoopProxy> main_message_loop)
  98     : pipe_(pipe),
  99       data_read_callback_(data_read_callback),
 100       failure_callback_(failure_callback),
 101       main_message_loop_(main_message_loop) {
 102 }
 103
 104 void Channel::ChannelImpl::ReaderThreadRunner::Run() {
 105   while (true) {
 106     scoped_ptr<MessageContents> msg_contents(new MessageContents);
 107     bool success = ReadDataOnReaderThread(pipe_, msg_contents.get());
 108     if (success) {
 109       main_message_loop_->PostTask(FROM_HERE,
 110           base::Bind(data_read_callback_, base::Passed(msg_contents.Pass())));
 111     } else {
 112       main_message_loop_->PostTask(FROM_HERE, failure_callback_);
 113       // Because the read failed, we know we're going to quit. Don't bother
 114       // trying to read again.
 115       return;
 116     }
 117   }
 118 }
 119
 120 Channel::ChannelImpl::ChannelImpl(const IPC::ChannelHandle& channel_handle,
 121                                   Mode mode,
 122                                   Listener* listener)
 123     : ChannelReader(listener),
 124       mode_(mode),
 125       waiting_connect_(true),
 126       pipe_(-1),
 127       pipe_name_(channel_handle.name),
 128       weak_ptr_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(this)) {
 129   if (!CreatePipe(channel_handle)) {
 130     // The pipe may have been closed already.
 131     const char *modestr = (mode_ & MODE_SERVER_FLAG) ? "server" : "client";
 132     LOG(WARNING) << "Unable to create pipe named \"" << channel_handle.name
 133                  << "\" in " << modestr << " mode";
 134   }
 135 }
 136
 137 Channel::ChannelImpl::~ChannelImpl() {
 138   Close();
 139 }
 140
 141 bool Channel::ChannelImpl::Connect() {
 142   if (pipe_ == -1) {
 143     DLOG(INFO) << "Channel creation failed: " << pipe_name_;
 144     return false;
 145   }
 146
 147   // Note that Connect is called on the "Channel" thread (i.e., the same thread
 148   // where Channel::Send will be called, and the same thread that should receive
 149   // messages). The constructor might be invoked on another thread (see
 150   // ChannelProxy for an example of that). Therefore, we must wait until Connect
 151   // is called to decide which MessageLoopProxy to pass to ReaderThreadRunner.
 152   reader_thread_runner_.reset(
 153       new ReaderThreadRunner(
 154           pipe_,
 155           base::Bind(&Channel::ChannelImpl::DidRecvMsg,
 156                      weak_ptr_factory_.GetWeakPtr()),
 157           base::Bind(&Channel::ChannelImpl::ReadDidFail,
 158                      weak_ptr_factory_.GetWeakPtr()),
 159           base::MessageLoopProxy::current()));
 160   reader_thread_.reset(
 161       new base::DelegateSimpleThread(reader_thread_runner_.get(),
 162                                      "ipc_channel_nacl reader thread"));
 163   reader_thread_->Start();
 164   waiting_connect_ = false;
 165   // If there were any messages queued before connection, send them.
 166   ProcessOutgoingMessages();
 167   return true;
 168 }
 169
 170 void Channel::ChannelImpl::Close() {
 171   // For now, we assume that at shutdown, the reader thread will be woken with
 172   // a failure (see NaClIPCAdapter::BlockingRead and CloseChannel). Or... we
 173   // might simply be killed with no chance to clean up anyway :-).
 174   // If untrusted code tries to close the channel prior to shutdown, it's likely
 175   // to hang.
 176   // TODO(dmichael): Can we do anything smarter here to make sure the reader
 177   //                 thread wakes up and quits?
 178   reader_thread_->Join();
 179   close(pipe_);
 180   pipe_ = -1;
 181   reader_thread_runner_.reset();
 182   reader_thread_.reset();
 183   read_queue_.clear();
 184   output_queue_.clear();
 185 }
 186
 187 bool Channel::ChannelImpl::Send(Message* message) {
 188   DVLOG(2) << "sending message @" << message << " on channel @" << this
 189            << " with type " << message->type();
 190   scoped_ptr<Message> message_ptr(message);
 191
 192 #ifdef IPC_MESSAGE_LOG_ENABLED
 193   Logging::GetInstance()->OnSendMessage(message_ptr.get(), "");
 194 #endif  // IPC_MESSAGE_LOG_ENABLED
 195
 196   message->TraceMessageBegin();
 197   output_queue_.push_back(linked_ptr<Message>(message_ptr.release()));
 198   if (!waiting_connect_)
 199     return ProcessOutgoingMessages();
 200
 201   return true;
 202 }
 203
 204 void Channel::ChannelImpl::DidRecvMsg(scoped_ptr<MessageContents> contents) {
 205   // Close sets the pipe to -1. It's possible we'll get a buffer sent to us from
 206   // the reader thread after Close is called. If so, we ignore it.
 207   if (pipe_ == -1)
 208     return;
 209
 210   linked_ptr<std::vector<char> > data(new std::vector<char>);
 211   data->swap(contents->data);
 212   read_queue_.push_back(data);
 213
 214   input_fds_.insert(input_fds_.end(),
 215                     contents->fds.begin(), contents->fds.end());
 216   contents->fds.clear();
 217
 218   // In POSIX, we would be told when there are bytes to read by implementing
 219   // OnFileCanReadWithoutBlocking in MessageLoopForIO::Watcher. In NaCl, we
 220   // instead know at this point because the reader thread posted some data to
 221   // us.
 222   ProcessIncomingMessages();
 223 }
 224
 225 void Channel::ChannelImpl::ReadDidFail() {
 226   Close();
 227 }
 228
 229 bool Channel::ChannelImpl::CreatePipe(
 230     const IPC::ChannelHandle& channel_handle) {
 231   DCHECK(pipe_ == -1);
 232
 233   // There's one possible case in NaCl:
 234   // 1) It's a channel wrapping a pipe that is given to us.
 235   // We don't support these:
 236   // 2) It's for a named channel.
 237   // 3) It's for a client that we implement ourself.
 238   // 4) It's the initial IPC channel.
 239
 240   if (channel_handle.socket.fd == -1) {
 241     NOTIMPLEMENTED();
 242     return false;
 243   }
 244   pipe_ = channel_handle.socket.fd;
 245   return true;
 246 }
 247
 248 bool Channel::ChannelImpl::ProcessOutgoingMessages() {
 249   DCHECK(!waiting_connect_);  // Why are we trying to send messages if there's
 250                               // no connection?
 251   if (output_queue_.empty())
 252     return true;
 253
 254   if (pipe_ == -1)
 255     return false;
 256
 257   // Write out all the messages. The trusted implementation is guaranteed to not
 258   // block. See NaClIPCAdapter::Send for the implementation of imc_sendmsg.
 259   while (!output_queue_.empty()) {
 260     linked_ptr<Message> msg = output_queue_.front();
 261     output_queue_.pop_front();
 262
 263     int fds[FileDescriptorSet::kMaxDescriptorsPerMessage];
 264     const size_t num_fds = msg->file_descriptor_set()->size();
 265     DCHECK(num_fds <= FileDescriptorSet::kMaxDescriptorsPerMessage);
 266     msg->file_descriptor_set()->GetDescriptors(fds);
 267
 268     NaClImcMsgIoVec iov = { const_cast<void*>(msg->data()), msg->size() };
 269     NaClImcMsgHdr msgh = { &iov, 1, fds, num_fds };
 270     ssize_t bytes_written = imc_sendmsg(pipe_, &msgh, 0);
 271
 272     DCHECK(bytes_written);  // The trusted side shouldn't return 0.
 273     if (bytes_written < 0) {
 274       // The trusted side should only ever give us an error of EPIPE. We
 275       // should never be interrupted, nor should we get EAGAIN.
 276       DCHECK(errno == EPIPE);
 277       Close();
 278       PLOG(ERROR) << "pipe_ error on "
 279                   << pipe_
 280                   << " Currently writing message of size: "
 281                   << msg->size();
 282       return false;
 283     } else {
 284       msg->file_descriptor_set()->CommitAll();
 285     }
 286
 287     // Message sent OK!
 288     DVLOG(2) << "sent message @" << msg.get() << " with type " << msg->type()
 289              << " on fd " << pipe_;
 290   }
 291   return true;
 292 }
 293
 294 Channel::ChannelImpl::ReadState Channel::ChannelImpl::ReadData(
 295     char* buffer,
 296     int buffer_len,
 297     int* bytes_read) {
 298   *bytes_read = 0;
 299   if (pipe_ == -1)
 300     return READ_FAILED;
 301   if (read_queue_.empty())
 302     return READ_PENDING;
 303   while (!read_queue_.empty() && *bytes_read < buffer_len) {
 304     linked_ptr<std::vector<char> > vec(read_queue_.front());
 305     size_t bytes_to_read = buffer_len - *bytes_read;
 306     if (vec->size() <= bytes_to_read) {
 307       // We can read and discard the entire vector.
 308       std::copy(vec->begin(), vec->end(), buffer + *bytes_read);
 309       *bytes_read += vec->size();
 310       read_queue_.pop_front();
 311     } else {
 312       // Read all the bytes we can and discard them from the front of the
 313       // vector. (This can be slowish, since erase has to move the back of the
 314       // vector to the front, but it's hopefully a temporary hack and it keeps
 315       // the code simple).
 316       std::copy(vec->begin(), vec->begin() + bytes_to_read,
 317                 buffer + *bytes_read);
 318       vec->erase(vec->begin(), vec->begin() + bytes_to_read);
 319       *bytes_read += bytes_to_read;
 320     }
 321   }
 322   return READ_SUCCEEDED;
 323 }
 324
 325 bool Channel::ChannelImpl::WillDispatchInputMessage(Message* msg) {
 326   uint16 header_fds = msg->header()->num_fds;
 327   CHECK(header_fds == input_fds_.size());
 328   if (header_fds == 0)
 329     return true;  // Nothing to do.
 330
 331   // The shenaniganery below with &foo.front() requires input_fds_ to have
 332   // contiguous underlying storage (such as a simple array or a std::vector).
 333   // This is why the header warns not to make input_fds_ a deque<>.
 334   msg->file_descriptor_set()->SetDescriptors(&input_fds_.front(),
 335                                              header_fds);
 336   input_fds_.clear();
 337   return true;
 338 }
 339
 340 bool Channel::ChannelImpl::DidEmptyInputBuffers() {
 341   // When the input data buffer is empty, the fds should be too.
 342   return input_fds_.empty();
 343 }
 344
 345 void Channel::ChannelImpl::HandleHelloMessage(const Message& msg) {
 346   // The trusted side IPC::Channel should handle the "hello" handshake; we
 347   // should not receive the "Hello" message.
 348   NOTREACHED();
 349 }
 350
 351 //------------------------------------------------------------------------------
 352 // Channel's methods simply call through to ChannelImpl.
 353
 354 Channel::Channel(const IPC::ChannelHandle& channel_handle,
 355                  Mode mode,
 356                  Listener* listener)
 357     : channel_impl_(new ChannelImpl(channel_handle, mode, listener)) {
 358 }
 359
 360 Channel::~Channel() {
 361   delete channel_impl_;
 362 }
 363
 364 bool Channel::Connect() {
 365   return channel_impl_->Connect();
 366 }
 367
 368 void Channel::Close() {
 369   channel_impl_->Close();
 370 }
 371
 372 void Channel::set_listener(Listener* listener) {
 373   channel_impl_->set_listener(listener);
 374 }
 375
 376 base::ProcessId Channel::peer_pid() const {
 377   // This shouldn't actually get used in the untrusted side of the proxy, and we
 378   // don't have the real pid anyway.
 379   return -1;
 380 }
 381
 382 bool Channel::Send(Message* message) {
 383   return channel_impl_->Send(message);
 384 }
 385
 386 }  // namespace IPC