Integrate WebUSB with Feature Policy

chrome/browser/usb/usb_tab_helper.cc

Index: chrome/browser/usb/usb_tab_helper.cc
diff --git a/chrome/browser/usb/usb_tab_helper.cc b/chrome/browser/usb/usb_tab_helper.cc
index 539e8787286bf26323895048f0251cc35e68c3e7..055183e282a3837963c0598b3d4d0cbc5af107c3 100644
--- a/chrome/browser/usb/usb_tab_helper.cc
+++ b/chrome/browser/usb/usb_tab_helper.cc
@@ -10,7 +10,11 @@
 #include "chrome/browser/ui/browser_finder.h"
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
 #include "chrome/browser/usb/web_usb_permission_provider.h"
+#include "content/public/browser/render_frame_host.h"
+#include "content/public/common/content_features.h"
 #include "device/usb/mojo/device_manager_impl.h"
+#include "mojo/public/cpp/bindings/message.h"
+#include "third_party/WebKit/public/platform/WebFeaturePolicy.h"
 
 #if defined(OS_ANDROID)
 #include "chrome/browser/android/usb/web_usb_chooser_service_android.h"
@@ -21,6 +25,15 @@
 using content::RenderFrameHost;
 using content::WebContents;
 
+namespace {
+
+// The renderer performs its own feature policy checks so a request that gets
+// to the browser process indicates malicous code.
+const char kFeaturePolicyViolation[] =
+    "Feature policy blocks access to WebUSB.";
+
+}  // namespace
+
 DEFINE_WEB_CONTENTS_USER_DATA_KEY(UsbTabHelper);
 
 struct FrameUsbServices {
@@ -50,6 +63,16 @@ void UsbTabHelper::CreateDeviceManager(
     RenderFrameHost* render_frame_host,
     mojo::InterfaceRequest<device::mojom::UsbDeviceManager> request) {
   DCHECK(WebContents::FromRenderFrameHost(render_frame_host) == web_contents());
+  if (base::FeatureList::IsEnabled(features::kFeaturePolicy)) {

[iclelland.google, 2017/05/02 14:42:52]

Could this block, and the identical one below, be extracted into a single
boolean "is USB enabled in RFH" method?

[Reilly Grant (use Gerrit), 2017/05/02 19:29:05]

Done.

+    if (!render_frame_host->IsFeatureEnabled(
+            blink::WebFeaturePolicyFeature::kUsb)) {
+      mojo::ReportBadMessage(kFeaturePolicyViolation);
+      return;
+    }
+  } else if (web_contents()->GetMainFrame() != render_frame_host) {
+    mojo::ReportBadMessage(kFeaturePolicyViolation);
+    return;
+  }
   device::usb::DeviceManagerImpl::Create(
       GetPermissionProvider(render_frame_host), std::move(request));
 }
@@ -57,6 +80,17 @@ void UsbTabHelper::CreateDeviceManager(
 void UsbTabHelper::CreateChooserService(
     content::RenderFrameHost* render_frame_host,
     mojo::InterfaceRequest<device::mojom::UsbChooserService> request) {
+  DCHECK(WebContents::FromRenderFrameHost(render_frame_host) == web_contents());
+  if (base::FeatureList::IsEnabled(features::kFeaturePolicy)) {
+    if (!render_frame_host->IsFeatureEnabled(
+            blink::WebFeaturePolicyFeature::kUsb)) {
+      mojo::ReportBadMessage(kFeaturePolicyViolation);
+      return;
+    }
+  } else if (web_contents()->GetMainFrame() != render_frame_host) {
+    mojo::ReportBadMessage(kFeaturePolicyViolation);
+    return;
+  }
   GetChooserService(render_frame_host, std::move(request));
 }