Avoid calling GetNamedPipeClientProcessId() which is not available on XP.

remoting/host/win/worker_process_launcher.cc

 // Copyright (c) 2012 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 "remoting/host/win/worker_process_launcher.h"
 
 #include <windows.h>
 #include <sddl.h>
 #include <limits>
 
@@ skipping 91 matching lines @@
 
   return delegate_->OnMessageReceived(message);
 }
 
 void WorkerProcessLauncher::OnChannelConnected(int32 peer_pid) {
   DCHECK(main_task_runner_->BelongsToCurrentThread());
   DCHECK(ipc_channel_.get() != NULL);
   DCHECK(pipe_.IsValid());
   DCHECK(process_exit_event_.IsValid());
 
-  // Get the actual peer's PID (i.e. reported by the OS) instead of the PID
-  // reported by the peer itself (|peer_pid|).
-  DWORD actual_peer_pid;
-  if (!GetNamedPipeClientProcessId(pipe_, &actual_peer_pid)) {
-    LOG_GETLASTERROR(ERROR) << "Failed to query the peer's PID";
-    Stop();
-    return;
-  }
-
-  delegate_->OnChannelConnected(actual_peer_pid);
+  // |peer_pid| is send by the client and cannot be trusted.
+  // GetNamedPipeClientProcessId() is not available on XP. The pipe's security
+  // descriptor is the only protection we currently have against malicious
+  // clients.
+  //
+  // If we'd like to be able to launch low-privileged workers and let them to

[dcaiafa, 2012/08/15 20:44:32]

nit: "...let them connect..."

[alexeypa (please no reviews), 2012/08/15 21:15:07]

Done.

+  // connect back, the pipe handle should be passed to the worker instead of
+  // the pipe name.
+  delegate_->OnChannelConnected();
 }
 
 void WorkerProcessLauncher::OnChannelError() {
   DCHECK(main_task_runner_->BelongsToCurrentThread());
   DCHECK(ipc_channel_.get() != NULL);
   DCHECK(pipe_.IsValid());
   DCHECK(process_exit_event_.IsValid());
 
   Stop();
 }
@@ skipping 70 matching lines @@
 }
 
 // N.B. Copied from src/content/common/child_process_host_impl.cc
 std::string WorkerProcessLauncher::GenerateRandomChannelId() {
   return base::StringPrintf("%d.%p.%d",
                             base::GetCurrentProcId(), this,
                             base::RandInt(0, std::numeric_limits<int>::max()));
 }
 
 } // namespace remoting