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.
5 #include "ipc/ipc_channel_posix.h"
10 #include <sys/socket.h>
12 #include <sys/types.h>
15 #if defined(OS_OPENBSD)
19 #if !defined(OS_NACL_NONSFI)
26 #include "base/command_line.h"
27 #include "base/files/file_path.h"
28 #include "base/files/file_util.h"
29 #include "base/location.h"
30 #include "base/logging.h"
31 #include "base/memory/scoped_ptr.h"
32 #include "base/memory/singleton.h"
33 #include "base/posix/eintr_wrapper.h"
34 #include "base/posix/global_descriptors.h"
35 #include "base/process/process_handle.h"
36 #include "base/rand_util.h"
37 #include "base/stl_util.h"
38 #include "base/strings/string_util.h"
39 #include "base/synchronization/lock.h"
40 #include "ipc/ipc_descriptors.h"
41 #include "ipc/ipc_listener.h"
42 #include "ipc/ipc_logging.h"
43 #include "ipc/ipc_message_attachment_set.h"
44 #include "ipc/ipc_message_utils.h"
45 #include "ipc/ipc_switches.h"
46 #include "ipc/unix_domain_socket_util.h"
50 // IPC channels on Windows use named pipes (CreateNamedPipe()) with
51 // channel ids as the pipe names. Channels on POSIX use sockets as
52 // pipes These don't quite line up.
54 // When creating a child subprocess we use a socket pair and the parent side of
55 // the fork arranges it such that the initial control channel ends up on the
56 // magic file descriptor kPrimaryIPCChannel in the child. Future
57 // connections (file descriptors) can then be passed via that
58 // connection via sendmsg().
60 // A POSIX IPC channel can also be set up as a server for a bound UNIX domain
61 // socket, and will handle multiple connect and disconnect sequences. Currently
62 // it is limited to one connection at a time.
64 //------------------------------------------------------------------------------
67 // The PipeMap class works around this quirk related to unit tests:
69 // When running as a server, we install the client socket in a
70 // specific file descriptor number (@kPrimaryIPCChannel). However, we
71 // also have to support the case where we are running unittests in the
72 // same process. (We do not support forking without execing.)
74 // Case 1: normal running
75 // The IPC server object will install a mapping in PipeMap from the
76 // name which it was given to the client pipe. When forking the client, the
77 // GetClientFileDescriptorMapping will ensure that the socket is installed in
78 // the magic slot (@kPrimaryIPCChannel). The client will search for the
79 // mapping, but it won't find any since we are in a new process. Thus the
80 // magic fd number is returned. Once the client connects, the server will
81 // close its copy of the client socket and remove the mapping.
83 // Case 2: unittests - client and server in the same process
84 // The IPC server will install a mapping as before. The client will search
85 // for a mapping and find out. It duplicates the file descriptor and
86 // connects. Once the client connects, the server will close the original
87 // copy of the client socket and remove the mapping. Thus, when the client
88 // object closes, it will close the only remaining copy of the client socket
89 // in the fd table and the server will see EOF on its side.
91 // TODO(port): a client process cannot connect to multiple IPC channels with
96 static PipeMap
* GetInstance() {
97 return Singleton
<PipeMap
>::get();
101 // Shouldn't have left over pipes.
102 DCHECK(map_
.empty());
105 // Lookup a given channel id. Return -1 if not found.
106 int Lookup(const std::string
& channel_id
) {
107 base::AutoLock
locked(lock_
);
109 ChannelToFDMap::const_iterator i
= map_
.find(channel_id
);
115 // Remove the mapping for the given channel id. No error is signaled if the
116 // channel_id doesn't exist
117 void Remove(const std::string
& channel_id
) {
118 base::AutoLock
locked(lock_
);
119 map_
.erase(channel_id
);
122 // Insert a mapping from @channel_id to @fd. It's a fatal error to insert a
123 // mapping if one already exists for the given channel_id
124 void Insert(const std::string
& channel_id
, int fd
) {
125 base::AutoLock
locked(lock_
);
128 ChannelToFDMap::const_iterator i
= map_
.find(channel_id
);
129 CHECK(i
== map_
.end()) << "Creating second IPC server (fd " << fd
<< ") "
130 << "for '" << channel_id
<< "' while first "
131 << "(fd " << i
->second
<< ") still exists";
132 map_
[channel_id
] = fd
;
137 typedef std::map
<std::string
, int> ChannelToFDMap
;
140 friend struct DefaultSingletonTraits
<PipeMap
>;
141 #if defined(OS_ANDROID)
142 friend void ::IPC::Channel::NotifyProcessForkedForTesting();
146 //------------------------------------------------------------------------------
148 bool SocketWriteErrorIsRecoverable() {
149 #if defined(OS_MACOSX)
150 // On OS X if sendmsg() is trying to send fds between processes and there
151 // isn't enough room in the output buffer to send the fd structure over
152 // atomically then EMSGSIZE is returned.
154 // EMSGSIZE presents a problem since the system APIs can only call us when
155 // there's room in the socket buffer and not when there is "enough" room.
157 // The current behavior is to return to the event loop when EMSGSIZE is
158 // received and hopefull service another FD. This is however still
159 // technically a busy wait since the event loop will call us right back until
160 // the receiver has read enough data to allow passing the FD over atomically.
161 return errno
== EAGAIN
|| errno
== EMSGSIZE
;
163 return errno
== EAGAIN
;
169 #if defined(OS_ANDROID)
170 // When we fork for simple tests on Android, we can't 'exec', so we need to
171 // reset these entries manually to get the expected testing behavior.
172 void Channel::NotifyProcessForkedForTesting() {
173 PipeMap::GetInstance()->map_
.clear();
177 //------------------------------------------------------------------------------
179 #if defined(OS_LINUX)
180 int ChannelPosix::global_pid_
= 0;
183 ChannelPosix::ChannelPosix(const IPC::ChannelHandle
& channel_handle
,
184 Mode mode
, Listener
* listener
)
185 : ChannelReader(listener
),
187 peer_pid_(base::kNullProcessId
),
188 is_blocked_on_write_(false),
189 waiting_connect_(true),
190 message_send_bytes_written_(0),
191 pipe_name_(channel_handle
.name
),
193 must_unlink_(false) {
194 memset(input_cmsg_buf_
, 0, sizeof(input_cmsg_buf_
));
195 if (!CreatePipe(channel_handle
)) {
196 // The pipe may have been closed already.
197 const char *modestr
= (mode_
& MODE_SERVER_FLAG
) ? "server" : "client";
198 LOG(WARNING
) << "Unable to create pipe named \"" << channel_handle
.name
199 << "\" in " << modestr
<< " mode";
203 ChannelPosix::~ChannelPosix() {
208 bool SocketPair(int* fd1
, int* fd2
) {
210 if (socketpair(AF_UNIX
, SOCK_STREAM
, 0, pipe_fds
) != 0) {
211 PLOG(ERROR
) << "socketpair()";
215 // Set both ends to be non-blocking.
216 if (fcntl(pipe_fds
[0], F_SETFL
, O_NONBLOCK
) == -1 ||
217 fcntl(pipe_fds
[1], F_SETFL
, O_NONBLOCK
) == -1) {
218 PLOG(ERROR
) << "fcntl(O_NONBLOCK)";
219 if (IGNORE_EINTR(close(pipe_fds
[0])) < 0)
220 PLOG(ERROR
) << "close";
221 if (IGNORE_EINTR(close(pipe_fds
[1])) < 0)
222 PLOG(ERROR
) << "close";
232 bool ChannelPosix::CreatePipe(
233 const IPC::ChannelHandle
& channel_handle
) {
234 DCHECK(!server_listen_pipe_
.is_valid() && !pipe_
.is_valid());
236 // Four possible cases:
237 // 1) It's a channel wrapping a pipe that is given to us.
238 // 2) It's for a named channel, so we create it.
239 // 3) It's for a client that we implement ourself. This is used
240 // in single-process unittesting.
241 // 4) It's the initial IPC channel:
242 // 4a) Client side: Pull the pipe out of the GlobalDescriptors set.
243 // 4b) Server side: create the pipe.
245 base::ScopedFD local_pipe
;
246 if (channel_handle
.socket
.fd
!= -1) {
247 // Case 1 from comment above.
248 local_pipe
.reset(channel_handle
.socket
.fd
);
249 #if defined(IPC_USES_READWRITE)
250 // Test the socket passed into us to make sure it is nonblocking.
251 // We don't want to call read/write on a blocking socket.
252 int value
= fcntl(local_pipe
.get(), F_GETFL
);
254 PLOG(ERROR
) << "fcntl(F_GETFL) " << pipe_name_
;
257 if (!(value
& O_NONBLOCK
)) {
258 LOG(ERROR
) << "Socket " << pipe_name_
<< " must be O_NONBLOCK";
261 #endif // IPC_USES_READWRITE
262 } else if (mode_
& MODE_NAMED_FLAG
) {
263 #if defined(OS_NACL_NONSFI)
265 << "IPC channels in nacl_helper_nonsfi should not be in NAMED mode.";
267 // Case 2 from comment above.
268 int local_pipe_fd
= -1;
270 if (mode_
& MODE_SERVER_FLAG
) {
271 if (!CreateServerUnixDomainSocket(base::FilePath(pipe_name_
),
277 } else if (mode_
& MODE_CLIENT_FLAG
) {
278 if (!CreateClientUnixDomainSocket(base::FilePath(pipe_name_
),
283 LOG(ERROR
) << "Bad mode: " << mode_
;
287 local_pipe
.reset(local_pipe_fd
);
288 #endif // !defined(OS_NACL_NONSFI)
290 local_pipe
.reset(PipeMap::GetInstance()->Lookup(pipe_name_
));
291 if (mode_
& MODE_CLIENT_FLAG
) {
292 if (local_pipe
.is_valid()) {
293 // Case 3 from comment above.
294 // We only allow one connection.
295 local_pipe
.reset(HANDLE_EINTR(dup(local_pipe
.release())));
296 PipeMap::GetInstance()->Remove(pipe_name_
);
298 // Case 4a from comment above.
299 // Guard against inappropriate reuse of the initial IPC channel. If
300 // an IPC channel closes and someone attempts to reuse it by name, the
301 // initial channel must not be recycled here. http://crbug.com/26754.
302 static bool used_initial_channel
= false;
303 if (used_initial_channel
) {
304 LOG(FATAL
) << "Denying attempt to reuse initial IPC channel for "
308 used_initial_channel
= true;
311 base::GlobalDescriptors::GetInstance()->Get(kPrimaryIPCChannel
));
313 } else if (mode_
& MODE_SERVER_FLAG
) {
314 // Case 4b from comment above.
315 if (local_pipe
.is_valid()) {
316 LOG(ERROR
) << "Server already exists for " << pipe_name_
;
317 // This is a client side pipe registered by other server and
318 // shouldn't be closed.
319 ignore_result(local_pipe
.release());
322 base::AutoLock
lock(client_pipe_lock_
);
323 int local_pipe_fd
= -1, client_pipe_fd
= -1;
324 if (!SocketPair(&local_pipe_fd
, &client_pipe_fd
))
326 local_pipe
.reset(local_pipe_fd
);
327 client_pipe_
.reset(client_pipe_fd
);
328 PipeMap::GetInstance()->Insert(pipe_name_
, client_pipe_fd
);
330 LOG(ERROR
) << "Bad mode: " << mode_
;
335 #if defined(IPC_USES_READWRITE)
336 // Create a dedicated socketpair() for exchanging file descriptors.
337 // See comments for IPC_USES_READWRITE for details.
338 if (mode_
& MODE_CLIENT_FLAG
) {
339 int fd_pipe_fd
= 1, remote_fd_pipe_fd
= -1;
340 if (!SocketPair(&fd_pipe_fd
, &remote_fd_pipe_fd
)) {
344 fd_pipe_
.reset(fd_pipe_fd
);
345 remote_fd_pipe_
.reset(remote_fd_pipe_fd
);
347 #endif // IPC_USES_READWRITE
349 if ((mode_
& MODE_SERVER_FLAG
) && (mode_
& MODE_NAMED_FLAG
)) {
350 #if defined(OS_NACL_NONSFI)
351 LOG(FATAL
) << "IPC channels in nacl_helper_nonsfi "
352 << "should not be in NAMED or SERVER mode.";
354 server_listen_pipe_
.reset(local_pipe
.release());
357 pipe_
.reset(local_pipe
.release());
362 bool ChannelPosix::Connect() {
363 if (!server_listen_pipe_
.is_valid() && !pipe_
.is_valid()) {
364 DLOG(WARNING
) << "Channel creation failed: " << pipe_name_
;
368 bool did_connect
= true;
369 if (server_listen_pipe_
.is_valid()) {
370 #if defined(OS_NACL_NONSFI)
371 LOG(FATAL
) << "IPC channels in nacl_helper_nonsfi "
372 << "should always be in client mode.";
374 // Watch the pipe for connections, and turn any connections into
376 base::MessageLoopForIO::current()->WatchFileDescriptor(
377 server_listen_pipe_
.get(),
379 base::MessageLoopForIO::WATCH_READ
,
380 &server_listen_connection_watcher_
,
384 did_connect
= AcceptConnection();
389 void ChannelPosix::CloseFileDescriptors(Message
* msg
) {
390 #if defined(OS_MACOSX)
391 // There is a bug on OSX which makes it dangerous to close
392 // a file descriptor while it is in transit. So instead we
393 // store the file descriptor in a set and send a message to
394 // the recipient, which is queued AFTER the message that
395 // sent the FD. The recipient will reply to the message,
396 // letting us know that it is now safe to close the file
397 // descriptor. For more information, see:
398 // http://crbug.com/298276
399 std::vector
<int> to_close
;
400 msg
->attachment_set()->ReleaseFDsToClose(&to_close
);
401 for (size_t i
= 0; i
< to_close
.size(); i
++) {
402 fds_to_close_
.insert(to_close
[i
]);
403 QueueCloseFDMessage(to_close
[i
], 2);
406 msg
->attachment_set()->CommitAll();
410 bool ChannelPosix::ProcessOutgoingMessages() {
411 DCHECK(!waiting_connect_
); // Why are we trying to send messages if there's
413 if (output_queue_
.empty())
416 if (!pipe_
.is_valid())
419 // Write out all the messages we can till the write blocks or there are no
420 // more outgoing messages.
421 while (!output_queue_
.empty()) {
422 Message
* msg
= output_queue_
.front();
424 size_t amt_to_write
= msg
->size() - message_send_bytes_written_
;
425 DCHECK_NE(0U, amt_to_write
);
426 const char* out_bytes
= reinterpret_cast<const char*>(msg
->data()) +
427 message_send_bytes_written_
;
429 struct msghdr msgh
= {0};
430 struct iovec iov
= {const_cast<char*>(out_bytes
), amt_to_write
};
433 char buf
[CMSG_SPACE(sizeof(int) *
434 MessageAttachmentSet::kMaxDescriptorsPerMessage
)];
436 ssize_t bytes_written
= 1;
439 if (message_send_bytes_written_
== 0 && !msg
->attachment_set()->empty()) {
440 // This is the first chunk of a message which has descriptors to send
441 struct cmsghdr
*cmsg
;
442 const unsigned num_fds
= msg
->attachment_set()->size();
444 DCHECK(num_fds
<= MessageAttachmentSet::kMaxDescriptorsPerMessage
);
445 if (msg
->attachment_set()->ContainsDirectoryDescriptor()) {
446 LOG(FATAL
) << "Panic: attempting to transport directory descriptor over"
447 " IPC. Aborting to maintain sandbox isolation.";
448 // If you have hit this then something tried to send a file descriptor
449 // to a directory over an IPC channel. Since IPC channels span
450 // sandboxes this is very bad: the receiving process can use openat
451 // with ".." elements in the path in order to reach the real
455 msgh
.msg_control
= buf
;
456 msgh
.msg_controllen
= CMSG_SPACE(sizeof(int) * num_fds
);
457 cmsg
= CMSG_FIRSTHDR(&msgh
);
458 cmsg
->cmsg_level
= SOL_SOCKET
;
459 cmsg
->cmsg_type
= SCM_RIGHTS
;
460 cmsg
->cmsg_len
= CMSG_LEN(sizeof(int) * num_fds
);
461 msg
->attachment_set()->PeekDescriptors(
462 reinterpret_cast<int*>(CMSG_DATA(cmsg
)));
463 msgh
.msg_controllen
= cmsg
->cmsg_len
;
465 // DCHECK_LE above already checks that
466 // num_fds < kMaxDescriptorsPerMessage so no danger of overflow.
467 msg
->header()->num_fds
= static_cast<uint16
>(num_fds
);
469 #if defined(IPC_USES_READWRITE)
470 if (!IsHelloMessage(*msg
)) {
471 // Only the Hello message sends the file descriptor with the message.
472 // Subsequently, we can send file descriptors on the dedicated
473 // fd_pipe_ which makes Seccomp sandbox operation more efficient.
474 struct iovec fd_pipe_iov
= { const_cast<char *>(""), 1 };
475 msgh
.msg_iov
= &fd_pipe_iov
;
476 fd_written
= fd_pipe_
.get();
478 HANDLE_EINTR(sendmsg(fd_pipe_
.get(), &msgh
, MSG_DONTWAIT
));
480 msgh
.msg_controllen
= 0;
481 if (bytes_written
> 0) {
482 CloseFileDescriptors(msg
);
485 #endif // IPC_USES_READWRITE
488 if (bytes_written
== 1) {
489 fd_written
= pipe_
.get();
490 #if defined(IPC_USES_READWRITE)
491 if ((mode_
& MODE_CLIENT_FLAG
) && IsHelloMessage(*msg
)) {
492 DCHECK_EQ(msg
->attachment_set()->size(), 1U);
494 if (!msgh
.msg_controllen
) {
496 HANDLE_EINTR(write(pipe_
.get(), out_bytes
, amt_to_write
));
498 #endif // IPC_USES_READWRITE
500 bytes_written
= HANDLE_EINTR(sendmsg(pipe_
.get(), &msgh
, MSG_DONTWAIT
));
503 if (bytes_written
> 0)
504 CloseFileDescriptors(msg
);
506 if (bytes_written
< 0 && !SocketWriteErrorIsRecoverable()) {
507 // We can't close the pipe here, because calling OnChannelError
508 // may destroy this object, and that would be bad if we are
509 // called from Send(). Instead, we return false and hope the
510 // caller will close the pipe. If they do not, the pipe will
511 // still be closed next time OnFileCanReadWithoutBlocking is
513 #if defined(OS_MACOSX)
514 // On OSX writing to a pipe with no listener returns EPERM.
515 if (errno
== EPERM
) {
519 if (errno
== EPIPE
) {
522 PLOG(ERROR
) << "pipe error on "
524 << " Currently writing message of size: "
529 if (static_cast<size_t>(bytes_written
) != amt_to_write
) {
530 if (bytes_written
> 0) {
531 // If write() fails with EAGAIN then bytes_written will be -1.
532 message_send_bytes_written_
+= bytes_written
;
535 // Tell libevent to call us back once things are unblocked.
536 is_blocked_on_write_
= true;
537 base::MessageLoopForIO::current()->WatchFileDescriptor(
540 base::MessageLoopForIO::WATCH_WRITE
,
545 message_send_bytes_written_
= 0;
548 DVLOG(2) << "sent message @" << msg
<< " on channel @" << this
549 << " with type " << msg
->type() << " on fd " << pipe_
.get();
550 delete output_queue_
.front();
557 bool ChannelPosix::Send(Message
* message
) {
558 DVLOG(2) << "sending message @" << message
<< " on channel @" << this
559 << " with type " << message
->type()
560 << " (" << output_queue_
.size() << " in queue)";
562 #ifdef IPC_MESSAGE_LOG_ENABLED
563 Logging::GetInstance()->OnSendMessage(message
, "");
564 #endif // IPC_MESSAGE_LOG_ENABLED
566 message
->TraceMessageBegin();
567 output_queue_
.push(message
);
568 if (!is_blocked_on_write_
&& !waiting_connect_
) {
569 return ProcessOutgoingMessages();
575 int ChannelPosix::GetClientFileDescriptor() const {
576 base::AutoLock
lock(client_pipe_lock_
);
577 return client_pipe_
.get();
580 base::ScopedFD
ChannelPosix::TakeClientFileDescriptor() {
581 base::AutoLock
lock(client_pipe_lock_
);
582 if (!client_pipe_
.is_valid())
583 return base::ScopedFD();
584 PipeMap::GetInstance()->Remove(pipe_name_
);
585 return client_pipe_
.Pass();
588 void ChannelPosix::CloseClientFileDescriptor() {
589 base::AutoLock
lock(client_pipe_lock_
);
590 if (!client_pipe_
.is_valid())
592 PipeMap::GetInstance()->Remove(pipe_name_
);
593 client_pipe_
.reset();
596 bool ChannelPosix::AcceptsConnections() const {
597 return server_listen_pipe_
.is_valid();
600 bool ChannelPosix::HasAcceptedConnection() const {
601 return AcceptsConnections() && pipe_
.is_valid();
604 #if !defined(OS_NACL_NONSFI)
605 // GetPeerEuid is not supported in nacl_helper_nonsfi.
606 bool ChannelPosix::GetPeerEuid(uid_t
* peer_euid
) const {
607 DCHECK(!(mode_
& MODE_SERVER
) || HasAcceptedConnection());
608 return IPC::GetPeerEuid(pipe_
.get(), peer_euid
);
612 void ChannelPosix::ResetToAcceptingConnectionState() {
613 // Unregister libevent for the unix domain socket and close it.
614 read_watcher_
.StopWatchingFileDescriptor();
615 write_watcher_
.StopWatchingFileDescriptor();
617 #if defined(IPC_USES_READWRITE)
619 remote_fd_pipe_
.reset();
620 #endif // IPC_USES_READWRITE
622 while (!output_queue_
.empty()) {
623 Message
* m
= output_queue_
.front();
628 // Close any outstanding, received file descriptors.
631 #if defined(OS_MACOSX)
632 // Clear any outstanding, sent file descriptors.
633 for (std::set
<int>::iterator i
= fds_to_close_
.begin();
634 i
!= fds_to_close_
.end();
636 if (IGNORE_EINTR(close(*i
)) < 0)
637 PLOG(ERROR
) << "close";
639 fds_to_close_
.clear();
644 bool ChannelPosix::IsNamedServerInitialized(
645 const std::string
& channel_id
) {
646 return base::PathExists(base::FilePath(channel_id
));
649 #if defined(OS_LINUX)
651 void ChannelPosix::SetGlobalPid(int pid
) {
656 // Called by libevent when we can read from the pipe without blocking.
657 void ChannelPosix::OnFileCanReadWithoutBlocking(int fd
) {
658 if (fd
== server_listen_pipe_
.get()) {
659 #if defined(OS_NACL_NONSFI)
661 << "IPC channels in nacl_helper_nonsfi should not be SERVER mode.";
664 if (!ServerAcceptConnection(server_listen_pipe_
.get(), &new_pipe
) ||
667 listener()->OnChannelListenError();
670 if (pipe_
.is_valid()) {
671 // We already have a connection. We only handle one at a time.
672 // close our new descriptor.
673 if (HANDLE_EINTR(shutdown(new_pipe
, SHUT_RDWR
)) < 0)
674 DPLOG(ERROR
) << "shutdown " << pipe_name_
;
675 if (IGNORE_EINTR(close(new_pipe
)) < 0)
676 DPLOG(ERROR
) << "close " << pipe_name_
;
677 listener()->OnChannelDenied();
680 pipe_
.reset(new_pipe
);
682 if ((mode_
& MODE_OPEN_ACCESS_FLAG
) == 0) {
683 // Verify that the IPC channel peer is running as the same user.
685 if (!GetPeerEuid(&client_euid
)) {
686 DLOG(ERROR
) << "Unable to query client euid";
687 ResetToAcceptingConnectionState();
690 if (client_euid
!= geteuid()) {
691 DLOG(WARNING
) << "Client euid is not authorised";
692 ResetToAcceptingConnectionState();
697 if (!AcceptConnection()) {
698 NOTREACHED() << "AcceptConnection should not fail on server";
700 waiting_connect_
= false;
702 } else if (fd
== pipe_
) {
703 if (waiting_connect_
&& (mode_
& MODE_SERVER_FLAG
)) {
704 waiting_connect_
= false;
706 if (!ProcessIncomingMessages()) {
707 // ClosePipeOnError may delete this object, so we mustn't call
708 // ProcessOutgoingMessages.
713 NOTREACHED() << "Unknown pipe " << fd
;
716 // If we're a server and handshaking, then we want to make sure that we
717 // only send our handshake message after we've processed the client's.
718 // This gives us a chance to kill the client if the incoming handshake
719 // is invalid. This also flushes any closefd messages.
720 if (!is_blocked_on_write_
) {
721 if (!ProcessOutgoingMessages()) {
727 // Called by libevent when we can write to the pipe without blocking.
728 void ChannelPosix::OnFileCanWriteWithoutBlocking(int fd
) {
729 DCHECK_EQ(pipe_
.get(), fd
);
730 is_blocked_on_write_
= false;
731 if (!ProcessOutgoingMessages()) {
736 bool ChannelPosix::AcceptConnection() {
737 base::MessageLoopForIO::current()->WatchFileDescriptor(
740 base::MessageLoopForIO::WATCH_READ
,
745 if (mode_
& MODE_CLIENT_FLAG
) {
746 // If we are a client we want to send a hello message out immediately.
747 // In server mode we will send a hello message when we receive one from a
749 waiting_connect_
= false;
750 return ProcessOutgoingMessages();
751 } else if (mode_
& MODE_SERVER_FLAG
) {
752 waiting_connect_
= true;
760 void ChannelPosix::ClosePipeOnError() {
761 if (HasAcceptedConnection()) {
762 ResetToAcceptingConnectionState();
763 listener()->OnChannelError();
766 if (AcceptsConnections()) {
767 listener()->OnChannelListenError();
769 listener()->OnChannelError();
774 int ChannelPosix::GetHelloMessageProcId() const {
775 int pid
= base::GetCurrentProcId();
776 #if defined(OS_LINUX)
777 // Our process may be in a sandbox with a separate PID namespace.
785 void ChannelPosix::QueueHelloMessage() {
786 // Create the Hello message
787 scoped_ptr
<Message
> msg(new Message(MSG_ROUTING_NONE
,
789 IPC::Message::PRIORITY_NORMAL
));
790 if (!msg
->WriteInt(GetHelloMessageProcId())) {
791 NOTREACHED() << "Unable to pickle hello message proc id";
793 #if defined(IPC_USES_READWRITE)
794 scoped_ptr
<Message
> hello
;
795 if (remote_fd_pipe_
.is_valid()) {
796 if (!msg
->WriteBorrowingFile(remote_fd_pipe_
.get())) {
797 NOTREACHED() << "Unable to pickle hello message file descriptors";
799 DCHECK_EQ(msg
->attachment_set()->size(), 1U);
801 #endif // IPC_USES_READWRITE
802 output_queue_
.push(msg
.release());
805 ChannelPosix::ReadState
ChannelPosix::ReadData(
809 if (!pipe_
.is_valid())
812 struct msghdr msg
= {0};
814 struct iovec iov
= {buffer
, static_cast<size_t>(buffer_len
)};
818 msg
.msg_control
= input_cmsg_buf_
;
820 // recvmsg() returns 0 if the connection has closed or EAGAIN if no data
821 // is waiting on the pipe.
822 #if defined(IPC_USES_READWRITE)
823 if (fd_pipe_
.is_valid()) {
824 *bytes_read
= HANDLE_EINTR(read(pipe_
.get(), buffer
, buffer_len
));
825 msg
.msg_controllen
= 0;
827 #endif // IPC_USES_READWRITE
829 msg
.msg_controllen
= sizeof(input_cmsg_buf_
);
830 *bytes_read
= HANDLE_EINTR(recvmsg(pipe_
.get(), &msg
, MSG_DONTWAIT
));
832 if (*bytes_read
< 0) {
833 if (errno
== EAGAIN
) {
835 #if defined(OS_MACOSX)
836 } else if (errno
== EPERM
) {
837 // On OSX, reading from a pipe with no listener returns EPERM
838 // treat this as a special case to prevent spurious error messages
842 } else if (errno
== ECONNRESET
|| errno
== EPIPE
) {
845 PLOG(ERROR
) << "pipe error (" << pipe_
.get() << ")";
848 } else if (*bytes_read
== 0) {
849 // The pipe has closed...
854 CloseClientFileDescriptor();
856 // Read any file descriptors from the message.
857 if (!ExtractFileDescriptorsFromMsghdr(&msg
))
859 return READ_SUCCEEDED
;
862 #if defined(IPC_USES_READWRITE)
863 bool ChannelPosix::ReadFileDescriptorsFromFDPipe() {
865 struct iovec fd_pipe_iov
= { &dummy
, 1 };
867 struct msghdr msg
= { 0 };
868 msg
.msg_iov
= &fd_pipe_iov
;
870 msg
.msg_control
= input_cmsg_buf_
;
871 msg
.msg_controllen
= sizeof(input_cmsg_buf_
);
872 ssize_t bytes_received
=
873 HANDLE_EINTR(recvmsg(fd_pipe_
.get(), &msg
, MSG_DONTWAIT
));
875 if (bytes_received
!= 1)
876 return true; // No message waiting.
878 if (!ExtractFileDescriptorsFromMsghdr(&msg
))
884 // On Posix, we need to fix up the file descriptors before the input message
887 // This will read from the input_fds_ (READWRITE mode only) and read more
888 // handles from the FD pipe if necessary.
889 bool ChannelPosix::WillDispatchInputMessage(Message
* msg
) {
890 uint16 header_fds
= msg
->header()->num_fds
;
892 return true; // Nothing to do.
894 // The message has file descriptors.
895 const char* error
= NULL
;
896 if (header_fds
> input_fds_
.size()) {
897 // The message has been completely received, but we didn't get
898 // enough file descriptors.
899 #if defined(IPC_USES_READWRITE)
900 if (!ReadFileDescriptorsFromFDPipe())
902 if (header_fds
> input_fds_
.size())
903 #endif // IPC_USES_READWRITE
904 error
= "Message needs unreceived descriptors";
907 if (header_fds
> MessageAttachmentSet::kMaxDescriptorsPerMessage
)
908 error
= "Message requires an excessive number of descriptors";
911 LOG(WARNING
) << error
912 << " channel:" << this
913 << " message-type:" << msg
->type()
914 << " header()->num_fds:" << header_fds
;
915 // Abort the connection.
920 // The shenaniganery below with &foo.front() requires input_fds_ to have
921 // contiguous underlying storage (such as a simple array or a std::vector).
922 // This is why the header warns not to make input_fds_ a deque<>.
923 msg
->attachment_set()->AddDescriptorsToOwn(&input_fds_
.front(), header_fds
);
924 input_fds_
.erase(input_fds_
.begin(), input_fds_
.begin() + header_fds
);
928 bool ChannelPosix::DidEmptyInputBuffers() {
929 // When the input data buffer is empty, the fds should be too. If this is
930 // not the case, we probably have a rogue renderer which is trying to fill
931 // our descriptor table.
932 return input_fds_
.empty();
935 bool ChannelPosix::ExtractFileDescriptorsFromMsghdr(msghdr
* msg
) {
936 // Check that there are any control messages. On OSX, CMSG_FIRSTHDR will
937 // return an invalid non-NULL pointer in the case that controllen == 0.
938 if (msg
->msg_controllen
== 0)
941 for (cmsghdr
* cmsg
= CMSG_FIRSTHDR(msg
);
943 cmsg
= CMSG_NXTHDR(msg
, cmsg
)) {
944 if (cmsg
->cmsg_level
== SOL_SOCKET
&& cmsg
->cmsg_type
== SCM_RIGHTS
) {
945 unsigned payload_len
= cmsg
->cmsg_len
- CMSG_LEN(0);
946 DCHECK_EQ(0U, payload_len
% sizeof(int));
947 const int* file_descriptors
= reinterpret_cast<int*>(CMSG_DATA(cmsg
));
948 unsigned num_file_descriptors
= payload_len
/ 4;
949 input_fds_
.insert(input_fds_
.end(),
951 file_descriptors
+ num_file_descriptors
);
953 // Check this after adding the FDs so we don't leak them.
954 if (msg
->msg_flags
& MSG_CTRUNC
) {
963 // No file descriptors found, but that's OK.
967 void ChannelPosix::ClearInputFDs() {
968 for (size_t i
= 0; i
< input_fds_
.size(); ++i
) {
969 if (IGNORE_EINTR(close(input_fds_
[i
])) < 0)
970 PLOG(ERROR
) << "close ";
975 void ChannelPosix::QueueCloseFDMessage(int fd
, int hops
) {
979 // Create the message
980 scoped_ptr
<Message
> msg(new Message(MSG_ROUTING_NONE
,
981 CLOSE_FD_MESSAGE_TYPE
,
982 IPC::Message::PRIORITY_NORMAL
));
983 if (!msg
->WriteInt(hops
- 1) || !msg
->WriteInt(fd
)) {
984 NOTREACHED() << "Unable to pickle close fd.";
986 // Send(msg.release());
987 output_queue_
.push(msg
.release());
997 void ChannelPosix::HandleInternalMessage(const Message
& msg
) {
998 // The Hello message contains only the process id.
999 PickleIterator
iter(msg
);
1001 switch (msg
.type()) {
1006 case Channel::HELLO_MESSAGE_TYPE
:
1008 if (!iter
.ReadInt(&pid
))
1011 #if defined(IPC_USES_READWRITE)
1012 if (mode_
& MODE_SERVER_FLAG
) {
1013 // With IPC_USES_READWRITE, the Hello message from the client to the
1014 // server also contains the fd_pipe_, which will be used for all
1015 // subsequent file descriptor passing.
1016 DCHECK_EQ(msg
.attachment_set()->size(), 1U);
1017 base::ScopedFD descriptor
;
1018 if (!msg
.ReadFile(&iter
, &descriptor
)) {
1021 fd_pipe_
.reset(descriptor
.release());
1023 #endif // IPC_USES_READWRITE
1025 listener()->OnChannelConnected(pid
);
1028 #if defined(OS_MACOSX)
1029 case Channel::CLOSE_FD_MESSAGE_TYPE
:
1031 if (!iter
.ReadInt(&hops
))
1033 if (!iter
.ReadInt(&fd
))
1036 if (fds_to_close_
.erase(fd
) > 0) {
1037 if (IGNORE_EINTR(close(fd
)) < 0)
1038 PLOG(ERROR
) << "close";
1043 QueueCloseFDMessage(fd
, hops
);
1050 void ChannelPosix::Close() {
1051 // Close can be called multiple time, so we need to make sure we're
1054 ResetToAcceptingConnectionState();
1057 unlink(pipe_name_
.c_str());
1058 must_unlink_
= false;
1061 if (server_listen_pipe_
.is_valid()) {
1062 #if defined(OS_NACL_NONSFI)
1064 << "IPC channels in nacl_helper_nonsfi should not be SERVER mode.";
1066 server_listen_pipe_
.reset();
1067 // Unregister libevent for the listening socket and close it.
1068 server_listen_connection_watcher_
.StopWatchingFileDescriptor();
1072 CloseClientFileDescriptor();
1075 base::ProcessId
ChannelPosix::GetPeerPID() const {
1079 base::ProcessId
ChannelPosix::GetSelfPID() const {
1080 return GetHelloMessageProcId();
1083 void ChannelPosix::ResetSafely(base::ScopedFD
* fd
) {
1090 // The CL [1] tightened the error check for closing FDs, but it turned
1091 // out that there are existing cases that hit the newly added check.
1092 // ResetSafely() is the workaround for that crash, turning it from
1093 // from PCHECK() to DPCHECK() so that it doesn't crash in production.
1094 // [1] https://crrev.com/ce44fef5fd60dd2be5c587d4b084bdcd36adcee4
1095 int fd_to_close
= fd
->release();
1096 if (-1 != fd_to_close
) {
1097 int rv
= IGNORE_EINTR(close(fd_to_close
));
1102 //------------------------------------------------------------------------------
1103 // Channel's methods
1106 scoped_ptr
<Channel
> Channel::Create(
1107 const IPC::ChannelHandle
&channel_handle
, Mode mode
, Listener
* listener
) {
1108 return make_scoped_ptr(new ChannelPosix(channel_handle
, mode
, listener
));
1112 std::string
Channel::GenerateVerifiedChannelID(const std::string
& prefix
) {
1113 // A random name is sufficient validation on posix systems, so we don't need
1114 // an additional shared secret.
1116 std::string id
= prefix
;
1120 return id
.append(GenerateUniqueRandomChannelID());
1124 bool Channel::IsNamedServerInitialized(
1125 const std::string
& channel_id
) {
1126 return ChannelPosix::IsNamedServerInitialized(channel_id
);
1129 #if defined(OS_LINUX)
1131 void Channel::SetGlobalPid(int pid
) {
1132 ChannelPosix::SetGlobalPid(pid
);