Update GnubbyAuthHandler to use the current session ID

remoting/host/security_key/gnubby_auth_handler_win.cc

Index: remoting/host/security_key/gnubby_auth_handler_win.cc
diff --git a/remoting/host/security_key/gnubby_auth_handler_win.cc b/remoting/host/security_key/gnubby_auth_handler_win.cc
index fa7a0a0805022951ccae83ebe604128075c5ea4b..98570e14d9fbec8cd5b3a40d32cdb2c951866b10 100644
--- a/remoting/host/security_key/gnubby_auth_handler_win.cc
+++ b/remoting/host/security_key/gnubby_auth_handler_win.cc
@@ -9,10 +9,13 @@
 #include <string>
 
 #include "base/bind.h"
+#include "base/location.h"
 #include "base/logging.h"
+#include "base/memory/weak_ptr.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/threading/thread_checker.h"
+#include "base/threading/thread_task_runner_handle.h"
 #include "base/time/time.h"
 #include "base/timer/timer.h"
 #include "base/win/win_util.h"
@@ -69,6 +72,7 @@ class GnubbyAuthHandlerWin : public GnubbyAuthHandler, public IPC::Listener {
                           const std::string& response) override;
   void SendErrorAndCloseConnection(int gnubby_connection_id) override;
   void SetSendMessageCallback(const SendMessageCallback& callback) override;
+  void SetSessionIdCallback(const SessionIdCallback& callback) override;
   size_t GetActiveConnectionCountForTest() const override;
   void SetRequestTimeoutForTest(base::TimeDelta timeout) override;
 
@@ -100,6 +104,9 @@ class GnubbyAuthHandlerWin : public GnubbyAuthHandler, public IPC::Listener {
   // Sends a gnubby extension messages to the remote client when called.
   SendMessageCallback send_message_callback_;
 
+  // Used to retrieve the id of the remoted session.
+  SessionIdCallback session_id_callback_;
+
   // Tracks the IPC channel created for each security key forwarding session.
   ActiveChannels active_channels_;
 
@@ -117,19 +124,24 @@ class GnubbyAuthHandlerWin : public GnubbyAuthHandler, public IPC::Listener {
   // Ensures GnubbyAuthHandlerWin methods are called on the same thread.
   base::ThreadChecker thread_checker_;
 
+  base::WeakPtrFactory<GnubbyAuthHandlerWin> weak_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(GnubbyAuthHandlerWin);
 };
 
 std::unique_ptr<GnubbyAuthHandler> GnubbyAuthHandler::Create(
-    const SendMessageCallback& callback) {
+    const SendMessageCallback& send_message_callback,
+    const SessionIdCallback& session_id_callback) {
   std::unique_ptr<GnubbyAuthHandler> auth_handler(new GnubbyAuthHandlerWin());
-  auth_handler->SetSendMessageCallback(callback);
+  auth_handler->SetSendMessageCallback(send_message_callback);
+  auth_handler->SetSessionIdCallback(session_id_callback);
   return auth_handler;
 }
 
 GnubbyAuthHandlerWin::GnubbyAuthHandlerWin()
     : disconnect_timeout_(
-          base::TimeDelta::FromSeconds(kInitialRequestTimeoutSeconds)) {}
+          base::TimeDelta::FromSeconds(kInitialRequestTimeoutSeconds)),
+      weak_factory_(this) {}
 
 GnubbyAuthHandlerWin::~GnubbyAuthHandlerWin() {}
 
@@ -173,6 +185,12 @@ void GnubbyAuthHandlerWin::SetSendMessageCallback(
   send_message_callback_ = callback;
 }
 
+void GnubbyAuthHandlerWin::SetSessionIdCallback(
+    const SessionIdCallback& callback) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  session_id_callback_ = callback;
+}
+
 size_t GnubbyAuthHandlerWin::GetActiveConnectionCountForTest() const {
   return active_channels_.size();
 }
@@ -239,14 +257,30 @@ void GnubbyAuthHandlerWin::OnChannelConnected(int32_t peer_pid) {
                base::Bind(&GnubbyAuthHandlerWin::OnChannelError,
                           base::Unretained(this)));
 
-  // TODO(joedow): Use |peer_pid| to determine the originating session
-  // using ProcessIdToSessionId() and verify it is the one we created.
-  // Tracked via crbug.com/591746
+  // Verify the IPC connection attempt originated from the session we are
+  // currently remoting.  We don't want to service requests from arbitrary
+  // Windows sessions.
+  DWORD peer_session_id;
+  if (!ProcessIdToSessionId(peer_pid, &peer_session_id)) {
+    PLOG(ERROR) << "ProcessIdToSessionId() failed";
+    base::ThreadTaskRunnerHandle::Get()->PostTask(
+        FROM_HERE, base::Bind(&GnubbyAuthHandlerWin::OnChannelError,
+                              weak_factory_.GetWeakPtr()));
+    return;
+  }
+  if (peer_session_id != session_id_callback_.Run()) {
+    LOG(INFO) << "Ignoring connection attempt from outside remoted session.";
+    base::ThreadTaskRunnerHandle::Get()->PostTask(
+        FROM_HERE, base::Bind(&GnubbyAuthHandlerWin::OnChannelError,
+                              weak_factory_.GetWeakPtr()));
+    return;
+  }
 
   int new_connection_id = ++last_connection_id_;
   std::unique_ptr<RemoteSecurityKeyIpcServer> ipc_server(
       RemoteSecurityKeyIpcServer::Create(
-          new_connection_id, disconnect_timeout_, send_message_callback_,
+          new_connection_id, peer_session_id, disconnect_timeout_,
+          send_message_callback_,
           base::Bind(&GnubbyAuthHandlerWin::CloseSecurityKeyRequestIpcChannel,
                      base::Unretained(this), new_connection_id)));