Bug 856361. Part 2: Block data from a non-same-origin media resource entering a MediaStream from a media element. r=cpearce

--HG--
extra : rebase_source : fd0ac711b6be627b87634b5a6c518c82ffd46448

content/html/content/src/HTMLMediaElement.cpp

@@ -3251,9 +3251,16 @@ already_AddRefed<nsIPrincipal> HTMLMediaElement::GetCurrentPrincipal()
 
 void HTMLMediaElement::NotifyDecoderPrincipalChanged()
 {
+  nsRefPtr<nsIPrincipal> principal = GetCurrentPrincipal();
+
+  if (mDecoder) {
+    bool subsumes;
+    mDecoder->UpdateSameOriginStatus(
+      NS_SUCCEEDED(NodePrincipal()->Subsumes(principal, &subsumes)) && subsumes);
+  }
+
   for (uint32_t i = 0; i < mOutputStreams.Length(); ++i) {
     OutputMediaStream* ms = &mOutputStreams[i];
-    nsRefPtr<nsIPrincipal> principal = GetCurrentPrincipal();
     ms->mStream->CombineWithPrincipal(principal);
   }
 }

content/media/MediaDecoder.cpp

@@ -368,6 +368,7 @@ MediaDecoder::MediaDecoder() :
   mDuration(-1),
   mTransportSeekable(true),
   mMediaSeekable(true),
+  mSameOriginMedia(false),
   mReentrantMonitor("media.decoder"),
   mIsDormant(false),
   mPlayState(PLAY_STATE_PAUSED),
@@ -842,6 +843,18 @@ void MediaDecoder::DecodeError()
   Shutdown();
 }
 
+void MediaDecoder::UpdateSameOriginStatus(bool aSameOrigin)
+{
+  ReentrantMonitorAutoEnter mon(GetReentrantMonitor());
+  mSameOriginMedia = aSameOrigin;
+}
+
+bool MediaDecoder::IsSameOriginMedia()
+{
+  GetReentrantMonitor().AssertCurrentThreadIn();
+  return mSameOriginMedia;
+}
+
 bool MediaDecoder::IsSeeking() const
 {
   MOZ_ASSERT(NS_IsMainThread());

content/media/MediaDecoder.h

@@ -640,6 +640,10 @@ public:
   // The actual playback rate computation. The monitor must be held.
   virtual double ComputePlaybackRate(bool* aReliable);
 
+  // Return true when the media is same-origin with the element. The monitor
+  // must be held.
+  bool IsSameOriginMedia();
+
   // Returns true if we can play the entire media through without stopping
   // to buffer, given the current download and playback rates.
   bool CanPlayThrough();
@@ -736,6 +740,9 @@ public:
   // Notifies the element that decoding has failed.
   virtual void DecodeError();
 
+  // Indicate whether the media is same-origin with the element.
+  void UpdateSameOriginStatus(bool aSameOrigin);
+
   MediaDecoderOwner* GetOwner() MOZ_OVERRIDE;
 
 #ifdef MOZ_RAW
@@ -958,6 +965,10 @@ public:
   // True if the media is seekable (i.e. supports random access).
   bool mMediaSeekable;
 
+  // True if the media is same-origin with the element. Data can only be
+  // passed to MediaStreams when this is true.
+  bool mSameOriginMedia;
+
   /******
    * The following member variables can be accessed from any thread.
    ******/

content/media/MediaDecoderStateMachine.cpp

@@ -619,6 +619,10 @@ void MediaDecoderStateMachine::SendStreamData()
   if (mState == DECODER_STATE_DECODING_METADATA)
     return;
 
+  if (!mDecoder->IsSameOriginMedia()) {
+    return;
+  }
+
   // If there's still an audio thread alive, then we can't send any stream
   // data yet since both SendStreamData and the audio thread want to be in
   // charge of popping the audio queue. We're waiting for the audio thread