fix($compile): lower the $sce context for src on video, audio, and track.

Previously, video, audio, and track sources were $sce.RESOURCE_URL. This is not justified as
no attacks are possible through these attributes as far as I can tell. This change is not
breaking, and uses of $sce.trustAsResourceUrl before assigning to src or ng-src attributes
will just be silently ignored.

Author: rjamet

src/ng/compile.js

@@ -3151,13 +3151,16 @@ function $CompileProvider($provide, $$sanitizeUriProvider) {
         return $sce.HTML;
       }
       var tag = nodeName_(node);
+      // All tags with src attributes require a RESOURCE_URL value, except for
+      // img and various html5 media tags.
+      if (attrNormalizedName === 'src' || attrNormalizedName === 'ngSrc') {
+        if (['img', 'video', 'audio', 'track'].indexOf(tag) === -1) {
+          return $sce.RESOURCE_URL;
+        }
       // maction[xlink:href] can source SVG.  It's not limited to <maction>.
-      if (attrNormalizedName === 'xlinkHref' ||
-          (tag === 'form' && attrNormalizedName === 'action') ||
-          // links can be stylesheets or imports, which can run script in the current origin
-          (tag === 'link' && attrNormalizedName === 'href') ||
-          (tag !== 'img' && (attrNormalizedName === 'src' ||
-                            attrNormalizedName === 'ngSrc'))) {
+      } else if (attrNormalizedName === 'xlinkHref' ||
+          (tag === 'form' && attrNormalizedName === 'action')
+      ) {
         return $sce.RESOURCE_URL;
       }
     }

src/ng/sce.js

@@ -537,7 +537,7 @@ function $SceDelegateProvider() {
  * | `$sce.HTML`         | For HTML that's safe to source into the application.  The {@link ng.directive:ngBindHtml ngBindHtml} directive uses this context for bindings. If an unsafe value is encountered and the {@link ngSanitize $sanitize} module is present this will sanitize the value instead of throwing an error. |
  * | `$sce.CSS`          | For CSS that's safe to source into the application.  Currently unused.  Feel free to use it in your own directives. |
  * | `$sce.URL`          | For URLs that are safe to follow as links.  Currently unused (`<a href=` and `<img src=` sanitize their urls and don't constitute an SCE context. |
- * | `$sce.RESOURCE_URL` | For URLs that are not only safe to follow as links, but whose contents are also safe to include in your application.  Examples include `ng-include`, `src` / `ngSrc` bindings for tags other than `IMG` (e.g. `IFRAME`, `OBJECT`, etc.)  <br><br>Note that `$sce.RESOURCE_URL` makes a stronger statement about the URL than `$sce.URL` does and therefore contexts requiring values trusted for `$sce.RESOURCE_URL` can be used anywhere that values trusted for `$sce.URL` are required. |
+ * | `$sce.RESOURCE_URL` | For URLs that are not only safe to follow as links, but whose contents are also safe to include in your application.  Examples include `ng-include`, `src` / `ngSrc` bindings for tags other than `IMG`, `VIDEO`, `AUDIO` and `TRACK` (e.g. `IFRAME`, `OBJECT`, etc.)  <br><br>Note that `$sce.RESOURCE_URL` makes a stronger statement about the URL than `$sce.URL` does and therefore contexts requiring values trusted for `$sce.RESOURCE_URL` can be used anywhere that values trusted for `$sce.URL` are required. |
  * | `$sce.JS`           | For JavaScript that is safe to execute in your application's context.  Currently unused.  Feel free to use it in your own directives. |
  *
  * ## Format of items in {@link ng.$sceDelegateProvider#resourceUrlWhitelist resourceUrlWhitelist}/{@link ng.$sceDelegateProvider#resourceUrlBlacklist Blacklist} <a name="resourceUrlPatternItem"></a>

test/ng/compileSpec.js

@@ -10152,6 +10152,18 @@ describe('$compile', function() {
       expect(element.attr('src')).toEqual('http://example.com/image2.png');
     }));
 
+    it('should NOT require trusted values for video / audio / track src', inject(function($rootScope, $compile, $sce) {
+      element = $compile('<video src="{{testUrl}}"></video>')($rootScope);
+      $rootScope.testUrl = 'http://example.com/image.mp4';
+      $rootScope.$digest();
+      expect(element.attr('src')).toEqual('http://example.com/image.mp4');
+
+      // But it should accept trusted values anyway.
+      $rootScope.testUrl = $sce.trustAsUrl('http://example.com/image2.mp4');
+      $rootScope.$digest();
+      expect(element.attr('src')).toEqual('http://example.com/image2.mp4');
+    }));
+
     it('should not sanitize attributes other than src', inject(function($compile, $rootScope) {
       element = $compile('<img title="{{testUrl}}"></img>')($rootScope);
       $rootScope.testUrl = 'javascript:doEvilStuff()';