blob: 462d442df3b98c82e387c173cb52f02696a24c5b [file] [log] [blame]
// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "ipc/ipc_channel_posix.h"
#include <errno.h>
#include <fcntl.h>
#include <stddef.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/un.h>
#include <string>
#include <map>
#include "base/command_line.h"
#include "base/eintr_wrapper.h"
#include "base/file_path.h"
#include "base/file_util.h"
#include "base/global_descriptors_posix.h"
#include "base/logging.h"
#include "base/memory/scoped_ptr.h"
#include "base/memory/singleton.h"
#include "base/process_util.h"
#include "base/stl_util.h"
#include "base/string_util.h"
#include "base/synchronization/lock.h"
#include "ipc/ipc_descriptors.h"
#include "ipc/ipc_switches.h"
#include "ipc/file_descriptor_set_posix.h"
#include "ipc/ipc_logging.h"
#include "ipc/ipc_message_utils.h"
namespace IPC {
// IPC channels on Windows use named pipes (CreateNamedPipe()) with
// channel ids as the pipe names. Channels on POSIX use sockets as
// pipes These don't quite line up.
//
// When creating a child subprocess we use a socket pair and the parent side of
// the fork arranges it such that the initial control channel ends up on the
// magic file descriptor kPrimaryIPCChannel in the child. Future
// connections (file descriptors) can then be passed via that
// connection via sendmsg().
//
// A POSIX IPC channel can also be set up as a server for a bound UNIX domain
// socket, and will handle multiple connect and disconnect sequences. Currently
// it is limited to one connection at a time.
//------------------------------------------------------------------------------
namespace {
// The PipeMap class works around this quirk related to unit tests:
//
// When running as a server, we install the client socket in a
// specific file descriptor number (@kPrimaryIPCChannel). However, we
// also have to support the case where we are running unittests in the
// same process. (We do not support forking without execing.)
//
// Case 1: normal running
// The IPC server object will install a mapping in PipeMap from the
// name which it was given to the client pipe. When forking the client, the
// GetClientFileDescriptorMapping will ensure that the socket is installed in
// the magic slot (@kPrimaryIPCChannel). The client will search for the
// mapping, but it won't find any since we are in a new process. Thus the
// magic fd number is returned. Once the client connects, the server will
// close its copy of the client socket and remove the mapping.
//
// Case 2: unittests - client and server in the same process
// The IPC server will install a mapping as before. The client will search
// for a mapping and find out. It duplicates the file descriptor and
// connects. Once the client connects, the server will close the original
// copy of the client socket and remove the mapping. Thus, when the client
// object closes, it will close the only remaining copy of the client socket
// in the fd table and the server will see EOF on its side.
//
// TODO(port): a client process cannot connect to multiple IPC channels with
// this scheme.
class PipeMap {
public:
static PipeMap* GetInstance() {
return Singleton<PipeMap>::get();
}
~PipeMap() {
// Shouldn't have left over pipes.
DCHECK(map_.empty());
}
// Lookup a given channel id. Return -1 if not found.
int Lookup(const std::string& channel_id) {
base::AutoLock locked(lock_);
ChannelToFDMap::const_iterator i = map_.find(channel_id);
if (i == map_.end())
return -1;
return i->second;
}
// Remove the mapping for the given channel id. No error is signaled if the
// channel_id doesn't exist
void RemoveAndClose(const std::string& channel_id) {
base::AutoLock locked(lock_);
ChannelToFDMap::iterator i = map_.find(channel_id);
if (i != map_.end()) {
if (HANDLE_EINTR(close(i->second)) < 0)
PLOG(ERROR) << "close " << channel_id;
map_.erase(i);
}
}
// Insert a mapping from @channel_id to @fd. It's a fatal error to insert a
// mapping if one already exists for the given channel_id
void Insert(const std::string& channel_id, int fd) {
base::AutoLock locked(lock_);
DCHECK_NE(-1, fd);
ChannelToFDMap::const_iterator i = map_.find(channel_id);
CHECK(i == map_.end()) << "Creating second IPC server (fd " << fd << ") "
<< "for '" << channel_id << "' while first "
<< "(fd " << i->second << ") still exists";
map_[channel_id] = fd;
}
private:
base::Lock lock_;
typedef std::map<std::string, int> ChannelToFDMap;
ChannelToFDMap map_;
friend struct DefaultSingletonTraits<PipeMap>;
};
//------------------------------------------------------------------------------
// Verify that kMaxPipeNameLength is a decent size.
COMPILE_ASSERT(sizeof(((sockaddr_un*)0)->sun_path) >= kMaxPipeNameLength,
BAD_SUN_PATH_LENGTH);
// Creates a unix domain socket bound to the specified name that is listening
// for connections.
bool CreateServerUnixDomainSocket(const std::string& pipe_name,
int* server_listen_fd) {
DCHECK(server_listen_fd);
DCHECK_GT(pipe_name.length(), 0u);
DCHECK_LT(pipe_name.length(), kMaxPipeNameLength);
if (pipe_name.length() == 0 || pipe_name.length() >= kMaxPipeNameLength) {
return false;
}
// Create socket.
int fd = socket(AF_UNIX, SOCK_STREAM, 0);
if (fd < 0) {
return false;
}
// Make socket non-blocking
if (fcntl(fd, F_SETFL, O_NONBLOCK) == -1) {
PLOG(ERROR) << "fcntl(O_NONBLOCK) " << pipe_name;
if (HANDLE_EINTR(close(fd)) < 0)
PLOG(ERROR) << "close " << pipe_name;
return false;
}
// Delete any old FS instances.
unlink(pipe_name.c_str());
// Make sure the path we need exists.
FilePath path(pipe_name);
FilePath dir_path = path.DirName();
if (!file_util::CreateDirectory(dir_path)) {
return false;
}
// Create unix_addr structure.
struct sockaddr_un unix_addr;
memset(&unix_addr, 0, sizeof(unix_addr));
unix_addr.sun_family = AF_UNIX;
int path_len = snprintf(unix_addr.sun_path, IPC::kMaxPipeNameLength,
"%s", pipe_name.c_str());
DCHECK_EQ(static_cast<int>(pipe_name.length()), path_len);
size_t unix_addr_len = offsetof(struct sockaddr_un,
sun_path) + path_len + 1;
// Bind the socket.
if (bind(fd, reinterpret_cast<const sockaddr*>(&unix_addr),
unix_addr_len) != 0) {
PLOG(ERROR) << "bind " << pipe_name;
if (HANDLE_EINTR(close(fd)) < 0)
PLOG(ERROR) << "close " << pipe_name;
return false;
}
// Start listening on the socket.
const int listen_queue_length = 1;
if (listen(fd, listen_queue_length) != 0) {
PLOG(ERROR) << "listen " << pipe_name;
if (HANDLE_EINTR(close(fd)) < 0)
PLOG(ERROR) << "close " << pipe_name;
return false;
}
*server_listen_fd = fd;
return true;
}
// Accept a connection on a socket we are listening to.
bool ServerAcceptConnection(int server_listen_fd, int* server_socket) {
DCHECK(server_socket);
int accept_fd = HANDLE_EINTR(accept(server_listen_fd, NULL, 0));
if (accept_fd < 0)
return false;
if (fcntl(accept_fd, F_SETFL, O_NONBLOCK) == -1) {
PLOG(ERROR) << "fcntl(O_NONBLOCK) " << accept_fd;
if (HANDLE_EINTR(close(accept_fd)) < 0)
PLOG(ERROR) << "close " << accept_fd;
return false;
}
*server_socket = accept_fd;
return true;
}
bool CreateClientUnixDomainSocket(const std::string& pipe_name,
int* client_socket) {
DCHECK(client_socket);
DCHECK_GT(pipe_name.length(), 0u);
DCHECK_LT(pipe_name.length(), kMaxPipeNameLength);
if (pipe_name.length() == 0 || pipe_name.length() >= kMaxPipeNameLength) {
return false;
}
// Create socket.
int fd = socket(AF_UNIX, SOCK_STREAM, 0);
if (fd < 0) {
PLOG(ERROR) << "socket " << pipe_name;
return false;
}
// Make socket non-blocking
if (fcntl(fd, F_SETFL, O_NONBLOCK) == -1) {
PLOG(ERROR) << "fcntl(O_NONBLOCK) " << pipe_name;
if (HANDLE_EINTR(close(fd)) < 0)
PLOG(ERROR) << "close " << pipe_name;
return false;
}
// Create server side of socket.
struct sockaddr_un server_unix_addr;
memset(&server_unix_addr, 0, sizeof(server_unix_addr));
server_unix_addr.sun_family = AF_UNIX;
int path_len = snprintf(server_unix_addr.sun_path, IPC::kMaxPipeNameLength,
"%s", pipe_name.c_str());
DCHECK_EQ(static_cast<int>(pipe_name.length()), path_len);
size_t server_unix_addr_len = offsetof(struct sockaddr_un,
sun_path) + path_len + 1;
if (HANDLE_EINTR(connect(fd, reinterpret_cast<sockaddr*>(&server_unix_addr),
server_unix_addr_len)) != 0) {
PLOG(ERROR) << "connect " << pipe_name;
if (HANDLE_EINTR(close(fd)) < 0)
PLOG(ERROR) << "close " << pipe_name;
return false;
}
*client_socket = fd;
return true;
}
bool SocketWriteErrorIsRecoverable() {
#if defined(OS_MACOSX)
// On OS X if sendmsg() is trying to send fds between processes and there
// isn't enough room in the output buffer to send the fd structure over
// atomically then EMSGSIZE is returned.
//
// EMSGSIZE presents a problem since the system APIs can only call us when
// there's room in the socket buffer and not when there is "enough" room.
//
// The current behavior is to return to the event loop when EMSGSIZE is
// received and hopefull service another FD. This is however still
// technically a busy wait since the event loop will call us right back until
// the receiver has read enough data to allow passing the FD over atomically.
return errno == EAGAIN || errno == EMSGSIZE;
#else
return errno == EAGAIN;
#endif // OS_MACOSX
}
} // namespace
//------------------------------------------------------------------------------
Channel::ChannelImpl::ChannelImpl(const IPC::ChannelHandle& channel_handle,
Mode mode, Listener* listener)
: mode_(mode),
is_blocked_on_write_(false),
waiting_connect_(true),
message_send_bytes_written_(0),
server_listen_pipe_(-1),
pipe_(-1),
client_pipe_(-1),
#if defined(IPC_USES_READWRITE)
fd_pipe_(-1),
remote_fd_pipe_(-1),
#endif // IPC_USES_READWRITE
pipe_name_(channel_handle.name),
listener_(listener),
must_unlink_(false) {
memset(input_buf_, 0, sizeof(input_buf_));
memset(input_cmsg_buf_, 0, sizeof(input_cmsg_buf_));
if (!CreatePipe(channel_handle)) {
// The pipe may have been closed already.
const char *modestr = (mode_ & MODE_SERVER_FLAG) ? "server" : "client";
// The pipe may have been closed already.
LOG(WARNING) << "Unable to create pipe named \"" << channel_handle.name
<< "\" in " << modestr << " mode";
}
}
Channel::ChannelImpl::~ChannelImpl() {
Close();
}
bool SocketPair(int* fd1, int* fd2) {
int pipe_fds[2];
if (socketpair(AF_UNIX, SOCK_STREAM, 0, pipe_fds) != 0) {
PLOG(ERROR) << "socketpair()";
return false;
}
// Set both ends to be non-blocking.
if (fcntl(pipe_fds[0], F_SETFL, O_NONBLOCK) == -1 ||
fcntl(pipe_fds[1], F_SETFL, O_NONBLOCK) == -1) {
PLOG(ERROR) << "fcntl(O_NONBLOCK)";
if (HANDLE_EINTR(close(pipe_fds[0])) < 0)
PLOG(ERROR) << "close";
if (HANDLE_EINTR(close(pipe_fds[1])) < 0)
PLOG(ERROR) << "close";
return false;
}
*fd1 = pipe_fds[0];
*fd2 = pipe_fds[1];
return true;
}
bool Channel::ChannelImpl::CreatePipe(
const IPC::ChannelHandle& channel_handle) {
DCHECK(server_listen_pipe_ == -1 && pipe_ == -1);
// Four possible cases:
// 1) It's a channel wrapping a pipe that is given to us.
// 2) It's for a named channel, so we create it.
// 3) It's for a client that we implement ourself. This is used
// in unittesting.
// 4) It's the initial IPC channel:
// 4a) Client side: Pull the pipe out of the GlobalDescriptors set.
// 4b) Server side: create the pipe.
int local_pipe = -1;
if (channel_handle.socket.fd != -1) {
// Case 1 from comment above.
local_pipe = channel_handle.socket.fd;
#if defined(IPC_USES_READWRITE)
// Test the socket passed into us to make sure it is nonblocking.
// We don't want to call read/write on a blocking socket.
int value = fcntl(local_pipe, F_GETFL);
if (value == -1) {
PLOG(ERROR) << "fcntl(F_GETFL) " << pipe_name_;
return false;
}
if (!(value & O_NONBLOCK)) {
LOG(ERROR) << "Socket " << pipe_name_ << " must be O_NONBLOCK";
return false;
}
#endif // IPC_USES_READWRITE
} else if (mode_ & MODE_NAMED_FLAG) {
// Case 2 from comment above.
if (mode_ & MODE_SERVER_FLAG) {
if (!CreateServerUnixDomainSocket(pipe_name_, &local_pipe)) {
return false;
}
must_unlink_ = true;
} else if (mode_ & MODE_CLIENT_FLAG) {
if (!CreateClientUnixDomainSocket(pipe_name_, &local_pipe)) {
return false;
}
} else {
LOG(ERROR) << "Bad mode: " << mode_;
return false;
}
} else {
local_pipe = PipeMap::GetInstance()->Lookup(pipe_name_);
if (mode_ & MODE_CLIENT_FLAG) {
if (local_pipe != -1) {
// Case 3 from comment above.
// We only allow one connection.
local_pipe = HANDLE_EINTR(dup(local_pipe));
PipeMap::GetInstance()->RemoveAndClose(pipe_name_);
} else {
// Case 4a from comment above.
// Guard against inappropriate reuse of the initial IPC channel. If
// an IPC channel closes and someone attempts to reuse it by name, the
// initial channel must not be recycled here. http://crbug.com/26754.
static bool used_initial_channel = false;
if (used_initial_channel) {
LOG(FATAL) << "Denying attempt to reuse initial IPC channel for "
<< pipe_name_;
return false;
}
used_initial_channel = true;
local_pipe =
base::GlobalDescriptors::GetInstance()->Get(kPrimaryIPCChannel);
}
} else if (mode_ & MODE_SERVER_FLAG) {
// Case 4b from comment above.
if (local_pipe != -1) {
LOG(ERROR) << "Server already exists for " << pipe_name_;
return false;
}
if (!SocketPair(&local_pipe, &client_pipe_))
return false;
PipeMap::GetInstance()->Insert(pipe_name_, client_pipe_);
} else {
LOG(ERROR) << "Bad mode: " << mode_;
return false;
}
}
#if defined(IPC_USES_READWRITE)
// Create a dedicated socketpair() for exchanging file descriptors.
// See comments for IPC_USES_READWRITE for details.
if (mode_ & MODE_CLIENT_FLAG) {
if (!SocketPair(&fd_pipe_, &remote_fd_pipe_)) {
return false;
}
}
#endif // IPC_USES_READWRITE
if ((mode_ & MODE_SERVER_FLAG) && (mode_ & MODE_NAMED_FLAG)) {
server_listen_pipe_ = local_pipe;
local_pipe = -1;
}
pipe_ = local_pipe;
return true;
}
bool Channel::ChannelImpl::Connect() {
if (server_listen_pipe_ == -1 && pipe_ == -1) {
DLOG(INFO) << "Channel creation failed: " << pipe_name_;
return false;
}
bool did_connect = true;
if (server_listen_pipe_ != -1) {
// Watch the pipe for connections, and turn any connections into
// active sockets.
MessageLoopForIO::current()->WatchFileDescriptor(
server_listen_pipe_,
true,
MessageLoopForIO::WATCH_READ,
&server_listen_connection_watcher_,
this);
} else {
did_connect = AcceptConnection();
}
return did_connect;
}
bool Channel::ChannelImpl::ProcessIncomingMessages() {
ssize_t bytes_read = 0;
struct msghdr msg = {0};
struct iovec iov = {input_buf_, Channel::kReadBufferSize};
msg.msg_iovlen = 1;
msg.msg_control = input_cmsg_buf_;
for (;;) {
msg.msg_iov = &iov;
if (bytes_read == 0) {
if (pipe_ == -1)
return false;
// Read from pipe.
// recvmsg() returns 0 if the connection has closed or EAGAIN if no data
// is waiting on the pipe.
#if defined(IPC_USES_READWRITE)
if (fd_pipe_ >= 0) {
bytes_read = HANDLE_EINTR(read(pipe_, input_buf_,
Channel::kReadBufferSize));
msg.msg_controllen = 0;
} else
#endif // IPC_USES_READWRITE
{
msg.msg_controllen = sizeof(input_cmsg_buf_);
bytes_read = HANDLE_EINTR(recvmsg(pipe_, &msg, MSG_DONTWAIT));
}
if (bytes_read < 0) {
if (errno == EAGAIN) {
return true;
#if defined(OS_MACOSX)
} else if (errno == EPERM) {
// On OSX, reading from a pipe with no listener returns EPERM
// treat this as a special case to prevent spurious error messages
// to the console.
return false;
#endif // OS_MACOSX
} else if (errno == ECONNRESET || errno == EPIPE) {
return false;
} else {
PLOG(ERROR) << "pipe error (" << pipe_ << ")";
return false;
}
} else if (bytes_read == 0) {
// The pipe has closed...
return false;
}
}
DCHECK(bytes_read);
if (client_pipe_ != -1) {
PipeMap::GetInstance()->RemoveAndClose(pipe_name_);
client_pipe_ = -1;
}
// a pointer to an array of |num_wire_fds| file descriptors from the read
const int* wire_fds = NULL;
unsigned num_wire_fds = 0;
// walk the list of control messages and, if we find an array of file
// descriptors, save a pointer to the array
// This next if statement is to work around an OSX issue where
// CMSG_FIRSTHDR will return non-NULL in the case that controllen == 0.
// Here's a test case:
//
// int main() {
// struct msghdr msg;
// msg.msg_control = &msg;
// msg.msg_controllen = 0;
// if (CMSG_FIRSTHDR(&msg))
// printf("Bug found!\n");
// }
if (msg.msg_controllen > 0) {
// On OSX, CMSG_FIRSTHDR doesn't handle the case where controllen is 0
// and will return a pointer into nowhere.
for (struct cmsghdr* cmsg = CMSG_FIRSTHDR(&msg); cmsg;
cmsg = CMSG_NXTHDR(&msg, cmsg)) {
if (cmsg->cmsg_level == SOL_SOCKET &&
cmsg->cmsg_type == SCM_RIGHTS) {
const unsigned payload_len = cmsg->cmsg_len - CMSG_LEN(0);
DCHECK_EQ(0U, payload_len % sizeof(int));
wire_fds = reinterpret_cast<int*>(CMSG_DATA(cmsg));
num_wire_fds = payload_len / 4;
if (msg.msg_flags & MSG_CTRUNC) {
LOG(ERROR) << "SCM_RIGHTS message was truncated"
<< " cmsg_len:" << cmsg->cmsg_len
<< " fd:" << pipe_;
for (unsigned i = 0; i < num_wire_fds; ++i)
if (HANDLE_EINTR(close(wire_fds[i])) < 0)
PLOG(ERROR) << "close " << i;
return false;
}
break;
}
}
}
// Process messages from input buffer.
const char *p;
const char *end;
if (input_overflow_buf_.empty()) {
p = input_buf_;
end = p + bytes_read;
} else {
if (input_overflow_buf_.size() >
static_cast<size_t>(kMaximumMessageSize - bytes_read)) {
input_overflow_buf_.clear();
LOG(ERROR) << "IPC message is too big";
return false;
}
input_overflow_buf_.append(input_buf_, bytes_read);
p = input_overflow_buf_.data();
end = p + input_overflow_buf_.size();
}
// A pointer to an array of |num_fds| file descriptors which includes any
// fds that have spilled over from a previous read.
const int* fds = NULL;
unsigned num_fds = 0;
unsigned fds_i = 0; // the index of the first unused descriptor
if (input_overflow_fds_.empty()) {
fds = wire_fds;
num_fds = num_wire_fds;
} else {
if (num_wire_fds > 0) {
const size_t prev_size = input_overflow_fds_.size();
input_overflow_fds_.resize(prev_size + num_wire_fds);
memcpy(&input_overflow_fds_[prev_size], wire_fds,
num_wire_fds * sizeof(int));
}
fds = &input_overflow_fds_[0];
num_fds = input_overflow_fds_.size();
}
while (p < end) {
const char* message_tail = Message::FindNext(p, end);
if (message_tail) {
int len = static_cast<int>(message_tail - p);
Message m(p, len);
const uint16 header_fds = m.header()->num_fds;
if (header_fds) {
// the message has file descriptors
const char* error = NULL;
if (header_fds > num_fds - fds_i) {
// the message has been completely received, but we didn't get
// enough file descriptors.
#if defined(IPC_USES_READWRITE)
char dummy;
struct iovec fd_pipe_iov = { &dummy, 1 };
msg.msg_iov = &fd_pipe_iov;
msg.msg_controllen = sizeof(input_cmsg_buf_);
ssize_t n = HANDLE_EINTR(recvmsg(fd_pipe_, &msg, MSG_DONTWAIT));
if (n == 1 && msg.msg_controllen > 0) {
for (struct cmsghdr* cmsg = CMSG_FIRSTHDR(&msg); cmsg;
cmsg = CMSG_NXTHDR(&msg, cmsg)) {
if (cmsg->cmsg_level == SOL_SOCKET &&
cmsg->cmsg_type == SCM_RIGHTS) {
const unsigned payload_len = cmsg->cmsg_len - CMSG_LEN(0);
DCHECK_EQ(0U, payload_len % sizeof(int));
wire_fds = reinterpret_cast<int*>(CMSG_DATA(cmsg));
num_wire_fds = payload_len / 4;
if (msg.msg_flags & MSG_CTRUNC) {
LOG(ERROR) << "SCM_RIGHTS message was truncated"
<< " cmsg_len:" << cmsg->cmsg_len
<< " fd:" << pipe_;
for (unsigned i = 0; i < num_wire_fds; ++i)
if (HANDLE_EINTR(close(wire_fds[i])) < 0)
PLOG(ERROR) << "close " << i;
return false;
}
break;
}
}
if (input_overflow_fds_.empty()) {
fds = wire_fds;
num_fds = num_wire_fds;
} else {
if (num_wire_fds > 0) {
const size_t prev_size = input_overflow_fds_.size();
input_overflow_fds_.resize(prev_size + num_wire_fds);
memcpy(&input_overflow_fds_[prev_size], wire_fds,
num_wire_fds * sizeof(int));
}
fds = &input_overflow_fds_[0];
num_fds = input_overflow_fds_.size();
}
}
if (header_fds > num_fds - fds_i)
#endif // IPC_USES_READWRITE
error = "Message needs unreceived descriptors";
}
if (header_fds >
FileDescriptorSet::MAX_DESCRIPTORS_PER_MESSAGE) {
// There are too many descriptors in this message
error = "Message requires an excessive number of descriptors";
}
if (error) {
LOG(WARNING) << error
<< " channel:" << this
<< " message-type:" << m.type()
<< " header()->num_fds:" << header_fds
<< " num_fds:" << num_fds
<< " fds_i:" << fds_i;
#if defined(CHROMIUM_SELINUX)
LOG(WARNING) << "In the case of SELinux this can be caused when "
"using a --user-data-dir to which the default "
"policy doesn't give the renderer access to. ";
#endif // CHROMIUM_SELINUX
// close the existing file descriptors so that we don't leak them
for (unsigned i = fds_i; i < num_fds; ++i)
if (HANDLE_EINTR(close(fds[i])) < 0)
PLOG(ERROR) << "close " << i;
input_overflow_fds_.clear();
// abort the connection
return false;
}
m.file_descriptor_set()->SetDescriptors(
&fds[fds_i], header_fds);
fds_i += header_fds;
}
DVLOG(2) << "received message on channel @" << this
<< " with type " << m.type() << " on fd " << pipe_;
if (IsHelloMessage(&m)) {
// The Hello message contains only the process id.
void *iter = NULL;
int pid;
if (!m.ReadInt(&iter, &pid)) {
NOTREACHED();
}
#if defined(IPC_USES_READWRITE)
if (mode_ & MODE_SERVER_FLAG) {
// With IPC_USES_READWRITE, the Hello message from the client to the
// server also contains the fd_pipe_, which will be used for all
// subsequent file descriptor passing.
DCHECK_EQ(m.file_descriptor_set()->size(), 1U);
base::FileDescriptor descriptor;
if (!m.ReadFileDescriptor(&iter, &descriptor)) {
NOTREACHED();
}
fd_pipe_ = descriptor.fd;
CHECK(descriptor.auto_close);
}
#endif // IPC_USES_READWRITE
listener_->OnChannelConnected(pid);
} else {
listener_->OnMessageReceived(m);
}
p = message_tail;
} else {
// Last message is partial.
break;
}
input_overflow_fds_ = std::vector<int>(&fds[fds_i], &fds[num_fds]);
fds_i = 0;
fds = vector_as_array(&input_overflow_fds_);
num_fds = input_overflow_fds_.size();
}
input_overflow_buf_.assign(p, end - p);
input_overflow_fds_ = std::vector<int>(&fds[fds_i], &fds[num_fds]);
// When the input data buffer is empty, the overflow fds should be too. If
// this is not the case, we probably have a rogue renderer which is trying
// to fill our descriptor table.
if (input_overflow_buf_.empty() && !input_overflow_fds_.empty()) {
// We close these descriptors in Close()
return false;
}
bytes_read = 0; // Get more data.
}
}
bool Channel::ChannelImpl::ProcessOutgoingMessages() {
DCHECK(!waiting_connect_); // Why are we trying to send messages if there's
// no connection?
if (output_queue_.empty())
return true;
if (pipe_ == -1)
return false;
// Write out all the messages we can till the write blocks or there are no
// more outgoing messages.
while (!output_queue_.empty()) {
Message* msg = output_queue_.front();
size_t amt_to_write = msg->size() - message_send_bytes_written_;
DCHECK_NE(0U, amt_to_write);
const char* out_bytes = reinterpret_cast<const char*>(msg->data()) +
message_send_bytes_written_;
struct msghdr msgh = {0};
struct iovec iov = {const_cast<char*>(out_bytes), amt_to_write};
msgh.msg_iov = &iov;
msgh.msg_iovlen = 1;
char buf[CMSG_SPACE(
sizeof(int[FileDescriptorSet::MAX_DESCRIPTORS_PER_MESSAGE]))];
ssize_t bytes_written = 1;
int fd_written = -1;
if (message_send_bytes_written_ == 0 &&
!msg->file_descriptor_set()->empty()) {
// This is the first chunk of a message which has descriptors to send
struct cmsghdr *cmsg;
const unsigned num_fds = msg->file_descriptor_set()->size();
DCHECK_LE(num_fds, FileDescriptorSet::MAX_DESCRIPTORS_PER_MESSAGE);
if (msg->file_descriptor_set()->ContainsDirectoryDescriptor()) {
LOG(FATAL) << "Panic: attempting to transport directory descriptor over"
" IPC. Aborting to maintain sandbox isolation.";
// If you have hit this then something tried to send a file descriptor
// to a directory over an IPC channel. Since IPC channels span
// sandboxes this is very bad: the receiving process can use openat
// with ".." elements in the path in order to reach the real
// filesystem.
}
msgh.msg_control = buf;
msgh.msg_controllen = CMSG_SPACE(sizeof(int) * num_fds);
cmsg = CMSG_FIRSTHDR(&msgh);
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
cmsg->cmsg_len = CMSG_LEN(sizeof(int) * num_fds);
msg->file_descriptor_set()->GetDescriptors(
reinterpret_cast<int*>(CMSG_DATA(cmsg)));
msgh.msg_controllen = cmsg->cmsg_len;
// DCHECK_LE above already checks that
// num_fds < MAX_DESCRIPTORS_PER_MESSAGE so no danger of overflow.
msg->header()->num_fds = static_cast<uint16>(num_fds);
#if defined(IPC_USES_READWRITE)
if (!IsHelloMessage(msg)) {
// Only the Hello message sends the file descriptor with the message.
// Subsequently, we can send file descriptors on the dedicated
// fd_pipe_ which makes Seccomp sandbox operation more efficient.
struct iovec fd_pipe_iov = { const_cast<char *>(""), 1 };
msgh.msg_iov = &fd_pipe_iov;
fd_written = fd_pipe_;
bytes_written = HANDLE_EINTR(sendmsg(fd_pipe_, &msgh, MSG_DONTWAIT));
msgh.msg_iov = &iov;
msgh.msg_controllen = 0;
if (bytes_written > 0) {
msg->file_descriptor_set()->CommitAll();
}
}
#endif // IPC_USES_READWRITE
}
if (bytes_written == 1) {
fd_written = pipe_;
#if defined(IPC_USES_READWRITE)
if ((mode_ & MODE_CLIENT_FLAG) && IsHelloMessage(msg)) {
DCHECK_EQ(msg->file_descriptor_set()->size(), 1U);
}
if (!msgh.msg_controllen) {
bytes_written = HANDLE_EINTR(write(pipe_, out_bytes, amt_to_write));
} else
#endif // IPC_USES_READWRITE
{
bytes_written = HANDLE_EINTR(sendmsg(pipe_, &msgh, MSG_DONTWAIT));
}
}
if (bytes_written > 0)
msg->file_descriptor_set()->CommitAll();
if (bytes_written < 0 && !SocketWriteErrorIsRecoverable()) {
#if defined(OS_MACOSX)
// On OSX writing to a pipe with no listener returns EPERM.
if (errno == EPERM) {
Close();
return false;
}
#endif // OS_MACOSX
if (errno == EPIPE) {
Close();
return false;
}
PLOG(ERROR) << "pipe error on "
<< fd_written
<< " Currently writing message of size: "
<< msg->size();
return false;
}
if (static_cast<size_t>(bytes_written) != amt_to_write) {
if (bytes_written > 0) {
// If write() fails with EAGAIN then bytes_written will be -1.
message_send_bytes_written_ += bytes_written;
}
// Tell libevent to call us back once things are unblocked.
is_blocked_on_write_ = true;
MessageLoopForIO::current()->WatchFileDescriptor(
pipe_,
false, // One shot
MessageLoopForIO::WATCH_WRITE,
&write_watcher_,
this);
return true;
} else {
message_send_bytes_written_ = 0;
// Message sent OK!
DVLOG(2) << "sent message @" << msg << " on channel @" << this
<< " with type " << msg->type() << " on fd " << pipe_;
delete output_queue_.front();
output_queue_.pop();
}
}
return true;
}
bool Channel::ChannelImpl::Send(Message* message) {
DVLOG(2) << "sending message @" << message << " on channel @" << this
<< " with type " << message->type()
<< " (" << output_queue_.size() << " in queue)";
#ifdef IPC_MESSAGE_LOG_ENABLED
Logging::GetInstance()->OnSendMessage(message, "");
#endif // IPC_MESSAGE_LOG_ENABLED
output_queue_.push(message);
if (!is_blocked_on_write_ && !waiting_connect_) {
return ProcessOutgoingMessages();
}
return true;
}
int Channel::ChannelImpl::GetClientFileDescriptor() const {
return client_pipe_;
}
bool Channel::ChannelImpl::AcceptsConnections() const {
return server_listen_pipe_ != -1;
}
bool Channel::ChannelImpl::HasAcceptedConnection() const {
return AcceptsConnections() && pipe_ != -1;
}
bool Channel::ChannelImpl::GetClientEuid(uid_t* client_euid) const {
DCHECK(HasAcceptedConnection());
#if defined(OS_MACOSX)
uid_t peer_euid;
gid_t peer_gid;
if (getpeereid(pipe_, &peer_euid, &peer_gid) != 0) {
PLOG(ERROR) << "getpeereid " << pipe_;
return false;
}
*client_euid = peer_euid;
return true;
#elif defined(OS_SOLARIS)
return false;
#else
struct ucred cred;
socklen_t cred_len = sizeof(cred);
if (getsockopt(pipe_, SOL_SOCKET, SO_PEERCRED, &cred, &cred_len) != 0) {
PLOG(ERROR) << "getsockopt " << pipe_;
return false;
}
if (cred_len < sizeof(cred)) {
NOTREACHED() << "Truncated ucred from SO_PEERCRED?";
return false;
}
*client_euid = cred.uid;
return true;
#endif
}
void Channel::ChannelImpl::ResetToAcceptingConnectionState() {
// Unregister libevent for the unix domain socket and close it.
read_watcher_.StopWatchingFileDescriptor();
write_watcher_.StopWatchingFileDescriptor();
if (pipe_ != -1) {
if (HANDLE_EINTR(close(pipe_)) < 0)
PLOG(ERROR) << "close pipe_ " << pipe_name_;
pipe_ = -1;
}
#if defined(IPC_USES_READWRITE)
if (fd_pipe_ != -1) {
if (HANDLE_EINTR(close(fd_pipe_)) < 0)
PLOG(ERROR) << "close fd_pipe_ " << pipe_name_;
fd_pipe_ = -1;
}
if (remote_fd_pipe_ != -1) {
if (HANDLE_EINTR(close(remote_fd_pipe_)) < 0)
PLOG(ERROR) << "close remote_fd_pipe_ " << pipe_name_;
remote_fd_pipe_ = -1;
}
#endif // IPC_USES_READWRITE
while (!output_queue_.empty()) {
Message* m = output_queue_.front();
output_queue_.pop();
delete m;
}
// Close any outstanding, received file descriptors.
for (std::vector<int>::iterator
i = input_overflow_fds_.begin(); i != input_overflow_fds_.end(); ++i) {
if (HANDLE_EINTR(close(*i)) < 0)
PLOG(ERROR) << "close";
}
input_overflow_fds_.clear();
}
// Called by libevent when we can read from the pipe without blocking.
void Channel::ChannelImpl::OnFileCanReadWithoutBlocking(int fd) {
bool send_server_hello_msg = false;
if (fd == server_listen_pipe_) {
int new_pipe = 0;
if (!ServerAcceptConnection(server_listen_pipe_, &new_pipe)) {
Close();
listener_->OnChannelListenError();
}
if (pipe_ != -1) {
// We already have a connection. We only handle one at a time.
// close our new descriptor.
if (HANDLE_EINTR(shutdown(new_pipe, SHUT_RDWR)) < 0)
PLOG(ERROR) << "shutdown " << pipe_name_;
if (HANDLE_EINTR(close(new_pipe)) < 0)
PLOG(ERROR) << "close " << pipe_name_;
listener_->OnChannelDenied();
return;
}
pipe_ = new_pipe;
if ((mode_ & MODE_OPEN_ACCESS_FLAG) == 0) {
// Verify that the IPC channel peer is running as the same user.
uid_t client_euid;
if (!GetClientEuid(&client_euid)) {
LOG(ERROR) << "Unable to query client euid";
ResetToAcceptingConnectionState();
return;
}
if (client_euid != geteuid()) {
LOG(WARNING) << "Client euid is not authorised";
ResetToAcceptingConnectionState();
return;
}
}
if (!AcceptConnection()) {
NOTREACHED() << "AcceptConnection should not fail on server";
}
send_server_hello_msg = true;
waiting_connect_ = false;
} else if (fd == pipe_) {
if (waiting_connect_ && (mode_ & MODE_SERVER_FLAG)) {
send_server_hello_msg = true;
waiting_connect_ = false;
}
if (!ProcessIncomingMessages()) {
// ClosePipeOnError may delete this object, so we mustn't call
// ProcessOutgoingMessages.
send_server_hello_msg = false;
ClosePipeOnError();
}
} else {
NOTREACHED() << "Unknown pipe " << fd;
}
// If we're a server and handshaking, then we want to make sure that we
// only send our handshake message after we've processed the client's.
// This gives us a chance to kill the client if the incoming handshake
// is invalid.
if (send_server_hello_msg) {
ProcessOutgoingMessages();
}
}
// Called by libevent when we can write to the pipe without blocking.
void Channel::ChannelImpl::OnFileCanWriteWithoutBlocking(int fd) {
DCHECK_EQ(pipe_, fd);
is_blocked_on_write_ = false;
if (!ProcessOutgoingMessages()) {
ClosePipeOnError();
}
}
bool Channel::ChannelImpl::AcceptConnection() {
MessageLoopForIO::current()->WatchFileDescriptor(pipe_,
true,
MessageLoopForIO::WATCH_READ,
&read_watcher_,
this);
QueueHelloMessage();
if (mode_ & MODE_CLIENT_FLAG) {
// If we are a client we want to send a hello message out immediately.
// In server mode we will send a hello message when we receive one from a
// client.
waiting_connect_ = false;
return ProcessOutgoingMessages();
} else if (mode_ & MODE_SERVER_FLAG) {
waiting_connect_ = true;
return true;
} else {
NOTREACHED();
return false;
}
}
void Channel::ChannelImpl::ClosePipeOnError() {
if (HasAcceptedConnection()) {
ResetToAcceptingConnectionState();
listener_->OnChannelError();
} else {
Close();
if (AcceptsConnections()) {
listener_->OnChannelListenError();
} else {
listener_->OnChannelError();
}
}
}
void Channel::ChannelImpl::QueueHelloMessage() {
// Create the Hello message
scoped_ptr<Message> msg(new Message(MSG_ROUTING_NONE,
HELLO_MESSAGE_TYPE,
IPC::Message::PRIORITY_NORMAL));
if (!msg->WriteInt(base::GetCurrentProcId())) {
NOTREACHED() << "Unable to pickle hello message proc id";
}
#if defined(IPC_USES_READWRITE)
scoped_ptr<Message> hello;
if (remote_fd_pipe_ != -1) {
if (!msg->WriteFileDescriptor(base::FileDescriptor(remote_fd_pipe_,
false))) {
NOTREACHED() << "Unable to pickle hello message file descriptors";
}
DCHECK_EQ(msg->file_descriptor_set()->size(), 1U);
}
#endif // IPC_USES_READWRITE
output_queue_.push(msg.release());
}
bool Channel::ChannelImpl::IsHelloMessage(const Message* m) const {
return m->routing_id() == MSG_ROUTING_NONE && m->type() == HELLO_MESSAGE_TYPE;
}
void Channel::ChannelImpl::Close() {
// Close can be called multiple time, so we need to make sure we're
// idempotent.
ResetToAcceptingConnectionState();
if (must_unlink_) {
unlink(pipe_name_.c_str());
must_unlink_ = false;
}
if (server_listen_pipe_ != -1) {
if (HANDLE_EINTR(close(server_listen_pipe_)) < 0)
PLOG(ERROR) << "close " << server_listen_pipe_;
server_listen_pipe_ = -1;
// Unregister libevent for the listening socket and close it.
server_listen_connection_watcher_.StopWatchingFileDescriptor();
}
if (client_pipe_ != -1) {
PipeMap::GetInstance()->RemoveAndClose(pipe_name_);
client_pipe_ = -1;
}
}
//------------------------------------------------------------------------------
// Channel's methods simply call through to ChannelImpl.
Channel::Channel(const IPC::ChannelHandle& channel_handle, Mode mode,
Listener* listener)
: channel_impl_(new ChannelImpl(channel_handle, mode, listener)) {
}
Channel::~Channel() {
delete channel_impl_;
}
bool Channel::Connect() {
return channel_impl_->Connect();
}
void Channel::Close() {
channel_impl_->Close();
}
void Channel::set_listener(Listener* listener) {
channel_impl_->set_listener(listener);
}
bool Channel::Send(Message* message) {
return channel_impl_->Send(message);
}
int Channel::GetClientFileDescriptor() const {
return channel_impl_->GetClientFileDescriptor();
}
bool Channel::AcceptsConnections() const {
return channel_impl_->AcceptsConnections();
}
bool Channel::HasAcceptedConnection() const {
return channel_impl_->HasAcceptedConnection();
}
bool Channel::GetClientEuid(uid_t* client_euid) const {
return channel_impl_->GetClientEuid(client_euid);
}
void Channel::ResetToAcceptingConnectionState() {
channel_impl_->ResetToAcceptingConnectionState();
}
} // namespace IPC