[Extensions] Add an access check before executing native code in the renderer

extensions/renderer/script_context.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "extensions/renderer/script_context.h"
 
+#include "base/command_line.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/values.h"
 #include "content/public/child/v8_value_converter.h"
+#include "content/public/common/content_switches.h"
 #include "content/public/common/url_constants.h"
 #include "content/public/renderer/render_frame.h"
 #include "extensions/common/constants.h"
 #include "extensions/common/extension.h"
 #include "extensions/common/extension_api.h"
 #include "extensions/common/extension_urls.h"
 #include "extensions/common/features/base_feature_provider.h"
 #include "extensions/common/manifest_handlers/sandboxed_page_info.h"
 #include "extensions/common/permissions/permissions_data.h"
 #include "extensions/renderer/renderer_extension_registry.h"
@@ skipping 176 matching lines @@
 
 v8::Local<v8::Value> ScriptContext::CallFunction(
     const v8::Local<v8::Function>& function) const {
   DCHECK(thread_checker_.CalledOnValidThread());
   return CallFunction(function, 0, nullptr);
 }
 
 Feature::Availability ScriptContext::GetAvailability(
     const std::string& api_name) {
   DCHECK(thread_checker_.CalledOnValidThread());
+  if (api_name == "test") {

[Devlin, 2016/03/30 22:02:28]

test api is special; the rest of them should pretty much just fall into the
normal code below.

+    bool allowed = base::CommandLine::ForCurrentProcess()->
+                       HasSwitch(::switches::kTestType);
+    Feature::AvailabilityResult result =
+        allowed ? Feature::IS_AVAILABLE : Feature::MISSING_COMMAND_LINE_SWITCH;
+    return Feature::Availability(result,
+                                 allowed ? "" : "Only allowed in tests");
+  }
   // Hack: Hosted apps should have the availability of messaging APIs based on
   // the URL of the page (which might have access depending on some extension
   // with externally_connectable), not whether the app has access to messaging
   // (which it won't).
   const Extension* extension = extension_.get();
   if (extension && extension->is_hosted_app() &&
       (api_name == "runtime.connect" || api_name == "runtime.sendMessage")) {
     extension = NULL;
   }
   return ExtensionAPI::GetSharedInstance()->IsAvailable(api_name, extension,
@@ skipping 249 matching lines @@
     v8::Local<v8::Value> argv[]) {
   return context_->CallFunction(function, argc, argv);
 }
 
 gin::ContextHolder* ScriptContext::Runner::GetContextHolder() {
   v8::HandleScope handle_scope(context_->isolate());
   return gin::PerContextData::From(context_->v8_context())->context_holder();
 }
 
 }  // namespace extensions