Bug 1129040 - Query the chrome process blocklist service prior to instantiating plugins in the content process. r=billm

dom/base/nsObjectLoadingContent.cpp

@@ -3258,8 +3258,9 @@ nsObjectLoadingContent::ShouldPlay(FallbackType &aReason, bool aIgnoreCurrentTyp
   }
 
   // Before we check permissions, get the blocklist state of this plugin to set
-  // the fallback reason correctly.
-  uint32_t blocklistState = nsIBlocklistService::STATE_NOT_BLOCKED;
+  // the fallback reason correctly. In the content process this will involve
+  // an ipc call to chrome.
+  uint32_t blocklistState = nsIBlocklistService::STATE_BLOCKED;
   pluginHost->GetBlocklistStateForType(mContentType,
                                        nsPluginHost::eExcludeNone,
                                        &blocklistState);

dom/plugins/base/nsPluginHost.cpp

@@ -1276,6 +1276,13 @@ nsPluginHost::GetPluginForContentProcess(uint32_t aPluginId, nsNPAPIPlugin** aPl
 
   nsPluginTag* pluginTag = PluginWithId(aPluginId);
   if (pluginTag) {
+    // When setting up a bridge, double check with chrome to see if this plugin
+    // is blocked hard. Note this does not protect against vulnerable plugins
+    // that the user has explicitly allowed. :(
+    if (pluginTag->IsBlocklisted()) {
+      return NS_ERROR_PLUGIN_BLOCKLISTED;
+    }
+
     nsresult rv = EnsurePluginLoaded(pluginTag);
     if (NS_FAILED(rv)) {
       return rv;