From 0e273ade3c006acafccb76c65ed174d6629f8896 Mon Sep 17 00:00:00 2001
From: Chris Pearce <cpearce@mozilla.com>
Date: Fri, 22 Apr 2016 08:31:18 +1200
Subject: [PATCH] Bug 1265587 - Force keystatuses to be cleared when Widevine
 keysessions are closed. r=gerald

The Widevine CDM, and I believe the Adobe CDM too probably, do not mark a
session's keys as unusable when a key session is closed. This means that
the CDMCaps' copy of the keys that are usable is wrong, and so if the media
with the same keys is reloaded with the same MediaKeys, Firefox will assume
that the keys are usable before the license for the keys has been
re-negotiated, and so decryption will fail.


MozReview-Commit-ID: 1kTDzwSD8PE

--HG--
extra : rebase_source : 89c480f36bfaec11ceb5ca1e8d798b0ae795eaea
---
 dom/html/HTMLMediaElement.cpp      |  3 +++
 dom/media/eme/CDMCallbackProxy.cpp | 13 +++++++++++++
 dom/media/eme/CDMCaps.cpp          | 12 ++++++++++++
 dom/media/eme/CDMCaps.h            |  4 ++++
 4 files changed, 32 insertions(+)

diff --git a/dom/html/HTMLMediaElement.cpp b/dom/html/HTMLMediaElement.cpp
index fddd0c20fe15..d19651177faf 100644
--- a/dom/html/HTMLMediaElement.cpp
+++ b/dom/html/HTMLMediaElement.cpp
@@ -5147,6 +5147,9 @@ already_AddRefed<Promise>
 HTMLMediaElement::SetMediaKeys(mozilla::dom::MediaKeys* aMediaKeys,
                                ErrorResult& aRv)
 {
+  LOG(LogLevel::Debug, ("%p SetMediaKeys(%p) mMediaKeys=%p mDecoder=%p",
+    this, aMediaKeys, mMediaKeys.get(), mDecoder.get()));
+
   if (MozAudioCaptured()) {
     aRv.Throw(NS_ERROR_DOM_NOT_SUPPORTED_ERR);
     return nullptr;
diff --git a/dom/media/eme/CDMCallbackProxy.cpp b/dom/media/eme/CDMCallbackProxy.cpp
index a7f92cdbca7c..3be34b55b1c9 100644
--- a/dom/media/eme/CDMCallbackProxy.cpp
+++ b/dom/media/eme/CDMCallbackProxy.cpp
@@ -215,6 +215,19 @@ CDMCallbackProxy::SessionClosed(const nsCString& aSessionId)
 {
   MOZ_ASSERT(mProxy->IsOnGMPThread());
 
+  bool keyStatusesChange = false;
+  {
+    CDMCaps::AutoLock caps(mProxy->Capabilites());
+    keyStatusesChange = caps.RemoveKeysForSession(NS_ConvertUTF8toUTF16(aSessionId));
+  }
+  if (keyStatusesChange) {
+    nsCOMPtr<nsIRunnable> task;
+    task = NS_NewRunnableMethodWithArg<nsString>(mProxy,
+      &CDMProxy::OnKeyStatusesChange,
+      NS_ConvertUTF8toUTF16(aSessionId));
+    NS_DispatchToMainThread(task);
+  }
+
   nsCOMPtr<nsIRunnable> task;
   task = NS_NewRunnableMethodWithArg<nsString>(mProxy,
                                                &CDMProxy::OnSessionClosed,
diff --git a/dom/media/eme/CDMCaps.cpp b/dom/media/eme/CDMCaps.cpp
index c8042375f7bf..e7db94d9dbd2 100644
--- a/dom/media/eme/CDMCaps.cpp
+++ b/dom/media/eme/CDMCaps.cpp
@@ -243,4 +243,16 @@ CDMCaps::AutoLock::GetSessionIdsForKeyId(const CencKeyId& aKeyId,
   }
 }
 
+bool
+CDMCaps::AutoLock::RemoveKeysForSession(const nsString& aSessionId)
+{
+  bool changed = false;
+  nsTArray<KeyStatus> statuses;
+  GetKeyStatusesForSession(aSessionId, statuses);
+  for (const KeyStatus& status : statuses) {
+    changed |= SetKeyStatus(status.mId, aSessionId, kGMPUnknown);
+  }
+  return changed;
+}
+
 } // namespace mozilla
diff --git a/dom/media/eme/CDMCaps.h b/dom/media/eme/CDMCaps.h
index 2d94de6198e8..3cc5a7076117 100644
--- a/dom/media/eme/CDMCaps.h
+++ b/dom/media/eme/CDMCaps.h
@@ -71,6 +71,10 @@ public:
     void GetSessionIdsForKeyId(const CencKeyId& aKeyId,
                                nsTArray<nsCString>& aOutSessionIds);
 
+    // Ensures all keys for a session are marked as 'unknown', i.e. removed.
+    // Returns true if a key status was changed.
+    bool RemoveKeysForSession(const nsString& aSessionId);
+
     // Sets the capabilities of the CDM. aCaps is the logical OR of the
     // GMP_EME_CAP_* flags from gmp-decryption.h.
     void SetCaps(uint64_t aCaps);