ipc: Create an unforgeable mechanism to get the process id of the sender.

ipc/attachment_broker_privileged_win.cc

 // Copyright 2015 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/attachment_broker_privileged_win.h"
 
 #include <windows.h>
 
 #include "base/process/process.h"
 #include "ipc/attachment_broker_messages.h"
@@ skipping 21 matching lines @@
       if (new_wire_format.handle == 0)
         return false;
       RouteDuplicatedHandle(new_wire_format);
       return true;
   }
   return false;
 }
 
 bool AttachmentBrokerPrivilegedWin::OnMessageReceived(const Message& msg) {
   bool handled = true;
-  IPC_BEGIN_MESSAGE_MAP(AttachmentBrokerPrivilegedWin, msg)
-    IPC_MESSAGE_HANDLER(AttachmentBrokerMsg_DuplicateWinHandle,
-                        OnDuplicateWinHandle)
+  switch (msg.type()) {
+    IPC_MESSAGE_HANDLER_GENERIC(AttachmentBrokerMsg_DuplicateWinHandle,
+                                OnDuplicateWinHandle(msg))
     IPC_MESSAGE_UNHANDLED(handled = false)
-  IPC_END_MESSAGE_MAP()
+  }
   return handled;
 }
 
 void AttachmentBrokerPrivilegedWin::RegisterCommunicationChannel(
     Channel* channel) {
   auto it = std::find(channels_.begin(), channels_.end(), channel);
   DCHECK(channels_.end() == it);
   channels_.push_back(channel);
 }
 
 void AttachmentBrokerPrivilegedWin::DeregisterCommunicationChannel(
     Channel* channel) {
   auto it = std::find(channels_.begin(), channels_.end(), channel);
   DCHECK(it != channels_.end());
   channels_.erase(it);
 }
 
 void AttachmentBrokerPrivilegedWin::OnDuplicateWinHandle(
-    const HandleWireFormat& wire_format,
-    base::ProcessId source_pid) {
+    const IPC::Message& message) {
+  AttachmentBrokerMsg_DuplicateWinHandle::Param param;
+  if (!AttachmentBrokerMsg_DuplicateWinHandle::Read(&message, &param))
+    return;
+  IPC::internal::HandleAttachmentWin::WireFormat wire_format =
+      base::get<0>(param);
+
   if (wire_format.destination_process == base::kNullProcessId)
     return;
 
   HandleWireFormat new_wire_format =
-      DuplicateWinHandle(wire_format, source_pid);
+      DuplicateWinHandle(wire_format, message.get_sender_pid());
   RouteDuplicatedHandle(new_wire_format);
 }
 
 void AttachmentBrokerPrivilegedWin::RouteDuplicatedHandle(
     const HandleWireFormat& wire_format) {
   // This process is the destination.
   if (wire_format.destination_process == base::Process::Current().Pid()) {
     scoped_refptr<BrokerableAttachment> attachment(
         new internal::HandleAttachmentWin(wire_format));
     HandleReceivedAttachment(attachment);
@@ skipping 38 matching lines @@
                                      FALSE, DUPLICATE_SAME_ACCESS);
 
     new_wire_format.handle = (result != 0) ? HandleToLong(new_handle) : 0;
   } else {
     new_wire_format.handle = 0;
   }
   return new_wire_format;
 }
 
 }  // namespace IPC