Add counters for various ways of loading scripts with bad mimetypes

third_party/WebKit/Source/core/dom/ScriptLoader.cpp

Index: third_party/WebKit/Source/core/dom/ScriptLoader.cpp
diff --git a/third_party/WebKit/Source/core/dom/ScriptLoader.cpp b/third_party/WebKit/Source/core/dom/ScriptLoader.cpp
index a7b90c6739fafc8dca761bb50c11c5a5d3962981..c1acd20dba3514b3884393b42ed82b44c64b96f5 100644
--- a/third_party/WebKit/Source/core/dom/ScriptLoader.cpp
+++ b/third_party/WebKit/Source/core/dom/ScriptLoader.cpp
@@ -333,6 +333,18 @@ bool isSVGScriptLoader(Element* element)
     return isSVGScriptElement(*element);
 }
 
+void ScriptLoader::logScriptMimetype(ScriptResource* resource, LocalFrame* frame, String mimetype)
+{
+    bool text = mimetype.lower().startsWith("text/");
+    bool application = mimetype.lower().startsWith("application/");
+    bool expectedJs = MIMETypeRegistry::isSupportedJavaScriptMIMEType(mimetype) || (text && isLegacySupportedJavaScriptLanguage(mimetype.substring(5)));
+    bool sameOrigin = m_element->document().securityOrigin()->canRequest(m_resource->url());
+    if (!expectedJs) {

[Nate Chapin, 2015/12/03 17:53:32]

Early exit is probably more readable than the remainder of the function wrapped
in an if().

[Dan Ehrenberg, 2015/12/04 19:28:53]

Done

+        UseCounter::Feature feature = sameOrigin ? (text ? UseCounter::SameOriginTextScript : application ? UseCounter::SameOriginApplicationScript : UseCounter::SameOriginOtherScript) : (text ? UseCounter::CrossOriginTextScript : application ? UseCounter::CrossOriginApplicationScript : UseCounter::CrossOriginOtherScript);

[Nate Chapin, 2015/12/03 17:53:32]

This is a bit much for 1 line, even by WebKit-style standards :)

[Dan Ehrenberg, 2015/12/04 19:28:53]

Well, I'd love to, but this is what git cl format seems to force me to do.

+        UseCounter::count(frame, feature);
+    }
+}
+
 bool ScriptLoader::executeScript(const ScriptSourceCode& sourceCode, double* compilationFinishTime)
 {
     ASSERT(m_alreadyStarted);
@@ -358,15 +370,20 @@ bool ScriptLoader::executeScript(const ScriptSourceCode& sourceCode, double* com
 
     if (m_isExternalScript) {
         ScriptResource* resource = m_resource ? m_resource.get() : sourceCode.resource();
-        if (resource && !resource->mimeTypeAllowedByNosniff()) {
-            contextDocument->addConsoleMessage(ConsoleMessage::create(SecurityMessageSource, ErrorMessageLevel, "Refused to execute script from '" + resource->url().elidedString() + "' because its MIME type ('" + resource->mimeType() + "') is not executable, and strict MIME type checking is enabled."));
-            return false;
-        }
-
-        if (resource && resource->mimeType().lower().startsWith("image/")) {
-            contextDocument->addConsoleMessage(ConsoleMessage::create(SecurityMessageSource, ErrorMessageLevel, "Refused to execute script from '" + resource->url().elidedString() + "' because its MIME type ('" + resource->mimeType() + "') is not executable."));
-            UseCounter::count(frame, UseCounter::BlockedSniffingImageToScript);
-            return false;
+        if (resource) {
+            if (!resource->mimeTypeAllowedByNosniff()) {
+                contextDocument->addConsoleMessage(ConsoleMessage::create(SecurityMessageSource, ErrorMessageLevel, "Refused to execute script from '" + resource->url().elidedString() + "' because its MIME type ('" + resource->mimeType() + "') is not executable, and strict MIME type checking is enabled."));
+                return false;
+            }
+
+            String mimetype = resource->mimeType();
+            if (mimetype.lower().startsWith("image/")) {
+                contextDocument->addConsoleMessage(ConsoleMessage::create(SecurityMessageSource, ErrorMessageLevel, "Refused to execute script from '" + resource->url().elidedString() + "' because its MIME type ('" + resource->mimeType() + "') is not executable."));
+                UseCounter::count(frame, UseCounter::BlockedSniffingImageToScript);
+                return false;
+            }
+
+            logScriptMimetype(resource, frame, mimetype);
         }
     }