Block NPAPI plugins by default

content/browser/plugin_service_impl.cc

 // Copyright (c) 2012 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 "content/browser/plugin_service_impl.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
 #include "base/files/file_path.h"
@@ skipping 41 matching lines @@
   // process during their lifetime.
   START_NPAPI_FLASH_AT_LEAST_ONCE,
   // Number of browser processes that have started at least one PPAPI Flash
   // process during their lifetime.
   START_PPAPI_FLASH_AT_LEAST_ONCE,
   // Total number of browser processes.
   TOTAL_BROWSER_PROCESSES,
   FLASH_USAGE_ENUM_COUNT
 };
 
+enum NPAPIPluginStatus {
+  // Platform does not support NPAPI.
+  NPAPI_STATUS_UNSUPPORTED,
+  // Platform supports NPAPI and NPAPI is disabled.
+  NPAPI_STATUS_DISABLED,
+  // Platform supports NPAPI and NPAPI is enabled.
+  NPAPI_STATUS_ENABLED,
+  NPAPI_STATUS_ENUM_COUNT
+};
+
 bool LoadPluginListInProcess() {
 #if defined(OS_WIN)
   return true;
 #else
   // If on POSIX, we don't want to load the list of NPAPI plugins in-process as
   // that causes instability.
 
   // Can't load the plugins on the utility thread when in single process mode
   // since that requires GTK which can only be used on the main thread.
   if (RenderProcessHost::run_renderer_in_process())
@@ skipping 64 matching lines @@
       host->Send(new ViewMsg_PurgePluginListCache(reload_pages));
   }
 }
 
 // static
 PluginServiceImpl* PluginServiceImpl::GetInstance() {
   return Singleton<PluginServiceImpl>::get();
 }
 
 PluginServiceImpl::PluginServiceImpl()
-    : filter_(NULL) {
+    : npapi_plugins_enabled_(false), filter_(NULL) {
   // Collect the total number of browser processes (which create
   // PluginServiceImpl objects, to be precise). The number is used to normalize
   // the number of processes which start at least one NPAPI/PPAPI Flash process.
   static bool counted = false;
   if (!counted) {
     counted = true;
     UMA_HISTOGRAM_ENUMERATION("Plugin.FlashUsage", TOTAL_BROWSER_PROCESSES,
                               FLASH_USAGE_ENUM_COUNT);
   }
 }
@@ skipping 16 matching lines @@
   base::FilePath path =
       command_line->GetSwitchValuePath(switches::kLoadPlugin);
   if (!path.empty())
     AddExtraPluginPath(path);
   path = command_line->GetSwitchValuePath(switches::kExtraPluginDir);
   if (!path.empty())
     PluginList::Singleton()->AddExtraPluginDir(path);
 
   if (command_line->HasSwitch(switches::kDisablePluginsDiscovery))
     PluginList::Singleton()->DisablePluginsDiscovery();
+#if defined(OS_WIN) || defined(OS_MACOSX)
+  npapi_plugins_enabled_ = command_line->HasSwitch(switches::kEnableNpapi);
+  UMA_HISTOGRAM_ENUMERATION(
+      "Plugin.NPAPIStatus",
+      npapi_plugins_enabled_ ? NPAPI_STATUS_ENABLED : NPAPI_STATUS_DISABLED,
+      NPAPI_STATUS_ENUM_COUNT);
+#else
+  UMA_HISTOGRAM_ENUMERATION("Plugin.NPAPIStatus", NPAPI_STATUS_UNSUPPORTED,
+                            NPAPI_STATUS_ENUM_COUNT);

[Ilya Sherman, 2015/01/20 20:45:18]

nit: To reduce the risk of typos creeping in to one of the two parallel
codepaths, I'd recommend writing this as:

#if defined(OS_WIN) || defined(OS_MACOSX)
NPAPIPluginStatus status =
    npapi_plugins_enabled_ ? NPAPI_STATUS_ENABLED : NPAPI_STATUS_DISABLED;
#else
NPAPIPluginStatus status = NPAPI_STATUS_UNSUPPORTED;
#endif
UMA_HISTOGRAM_ENUMERATION("Plugin.NPAPIStatus", status,
                          NPAPI_STATUS_ENUM_COUNT);

[Will Harris, 2015/01/20 22:35:11]

Done.

+#endif
 }
 
 void PluginServiceImpl::StartWatchingPlugins() {
   // Start watching for changes in the plugin list. This means watching
   // for changes in the Windows registry keys and on both Windows and POSIX
   // watch for changes in the paths that are expected to contain plugins.
 #if defined(OS_WIN)
   if (hkcu_key_.Create(HKEY_CURRENT_USER,
                        kRegistryMozillaPlugins,
                        KEY_NOTIFY) == ERROR_SUCCESS) {
@@ skipping 578 matching lines @@
 void PluginServiceImpl::UnregisterInternalPlugin(const base::FilePath& path) {
   PluginList::Singleton()->UnregisterInternalPlugin(path);
 }
 
 void PluginServiceImpl::GetInternalPlugins(
     std::vector<WebPluginInfo>* plugins) {
   PluginList::Singleton()->GetInternalPlugins(plugins);
 }
 
 bool PluginServiceImpl::NPAPIPluginsSupported() {
-#if defined(OS_WIN) || defined(OS_MACOSX)
-  return true;
-#else
-  return false;
-#endif
+  return npapi_plugins_enabled_;
 }
 
 void PluginServiceImpl::DisablePluginsDiscoveryForTesting() {
   PluginList::Singleton()->DisablePluginsDiscovery();
 }
 
+void PluginServiceImpl::EnableNpapiPluginsForTesting() {
+  npapi_plugins_enabled_ = true;
+}
+
 #if defined(OS_MACOSX)
 void PluginServiceImpl::AppActivated() {
   BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
                           base::Bind(&NotifyPluginsOfActivation));
 }
 #elif defined(OS_WIN)
 
 bool GetPluginPropertyFromWindow(
     HWND window, const wchar_t* plugin_atom_property,
     base::string16* plugin_property) {
@@ skipping 35 matching lines @@
 #endif
 
 bool PluginServiceImpl::PpapiDevChannelSupported(
     BrowserContext* browser_context,
     const GURL& document_url) {
   return content::GetContentClient()->browser()->
       IsPluginAllowedToUseDevChannelAPIs(browser_context, document_url);
 }
 
 }  // namespace content