Don't reuse the initial IPC channel

ipc/ipc_channel_posix.cc

 // Copyright (c) 2008 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>
@@ skipping 320 matching lines @@
     //   2b) Client side: Pull the pipe out of the GlobalDescriptors set.
     pipe_name_ = channel_id;
     pipe_ = ChannelNameToFD(pipe_name_);
     if (pipe_ < 0) {
       // Initial IPC channel.
       if (mode == MODE_SERVER) {
         if (!SocketPair(&pipe_, &client_pipe_))
           return false;
         AddChannelSocket(pipe_name_, client_pipe_);
       } else {
+        // 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";
+          return false;
+        }
+        used_initial_channel = true;
+
         pipe_ = Singleton<base::GlobalDescriptors>()->Get(kPrimaryIPCChannel);
       }
     } else {
       waiting_connect_ = mode == MODE_SERVER;
     }
   }
 
   // Create the Hello message to be sent when Connect is called
   scoped_ptr<Message> msg(new Message(MSG_ROUTING_NONE,
                                       HELLO_MESSAGE_TYPE,
@@ skipping 658 matching lines @@
 
 bool Channel::Send(Message* message) {
   return channel_impl_->Send(message);
 }
 
 int Channel::GetClientFileDescriptor() const {
   return channel_impl_->GetClientFileDescriptor();
 }
 
 }  // namespace IPC