[$csp4 adblockpluschrome] Issue 5241 - Add support for Content Security Policy filters

lib/csp.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 "use strict";
 
-// The webRequest API doesn't support WebSocket connection blocking in Microsoft
-// Edge and versions of Chrome before 58. Therefore for those we inject CSP
-// headers below as a workaround. See https://crbug.com/129353 and
-// https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/10297376/
-if (!browser.webRequest.ResourceType ||
-    !("WEBSOCKET" in browser.webRequest.ResourceType))
+const {defaultMatcher} = require("matcher");
+const {BlockingFilter, RegExpFilter} = require("filterClasses");
+const {getDecodedHostname, stringifyURL} = require("url");
+const {checkWhitelisted} = require("whitelisting");
+const {FilterNotifier} = require("filterNotifier");
+const devtools = require("devtools");
+
+const {typeMap} = RegExpFilter;
+
+browser.webRequest.onHeadersReceived.addListener(details =>
 {
-  const {defaultMatcher} = require("matcher");
-  const {BlockingFilter, RegExpFilter} = require("filterClasses");
-  const {getDecodedHostname} = require("url");
-  const {checkWhitelisted} = require("whitelisting");
+  let url = new URL(details.url);
+  let urlString = stringifyURL(url);
+  let hostname = getDecodedHostname(url);

[Sebastian Noack, 2018/03/14 20:19:42]

This seems inconsistent with the semantics of request blocking, where the
$domain option refers to the hostname of the parent document.

[kzar, 2018/03/15 13:10:13]

Well I suppose with request blocking we are generally blocking a request,
instead of injecting something that will then block child requests (or similar).
I'm not sure what else we can do here, do you have any suggestions?

[Sebastian Noack, 2018/03/15 17:14:25]

I don't see how the difference between blocking requests vs injecting headers,
calls for an inconsistency here. FWIW $popup filters have the same semantics.

We have access to the parentFrameId, and can get the parent frame's URL, to make
the behavior consistent here. So that ||foo.com$csp=...,domain=bar.com, only
injects a CSP on foo.com if embedded in a frame on bar.com.

[kzar, 2018/03/15 18:18:44]

Done, look OK?

+  let cspMatch = defaultMatcher.matchesAny(urlString, typeMap.CSP, hostname,
+                                           false, null, false);
+  if (cspMatch)
+  {
+    let page = new ext.Page({id: details.tabId, url: details.url});
+    let frame = ext.getFrame(details.tabId, details.frameId);
+    if (checkWhitelisted(page, frame, typeMap.DOCUMENT | typeMap.CSP))
+      return;
 
-  browser.webRequest.onHeadersReceived.addListener(details =>
-  {
-    let hostname = getDecodedHostname(new URL(details.url));
-    let match = defaultMatcher.matchesAny("", RegExpFilter.typeMap.WEBSOCKET,
-                                          hostname, false, null, true);
-    if (match instanceof BlockingFilter &&
-        !checkWhitelisted(new ext.Page({id: details.tabId}),
-                          ext.getFrame(details.tabId, details.frameId)))
+    // To avoid an extra matchesAny for the common case we assumed no
+    // $genericblock filters applied when searching for a matching $csp filter.
+    // We must now pay the price by first checking for a $genericblock filter
+    // and if necessary that our $csp filter is specific.
+    let specificOnly = checkWhitelisted(page, frame, typeMap.GENERICBLOCK);
+    if (specificOnly)
     {
-      details.responseHeaders.push({
-        name: "Content-Security-Policy",
-        // We're blocking WebSockets here by adding a connect-src restriction
-        // since the Chrome extension API does not allow us to intercept them.
-        // https://bugs.chromium.org/p/chromium/issues/detail?id=129353
-        //
-        // We also need the frame-src and object-src restrictions since CSPs
-        // are not inherited from the parent for documents with data: and blob:
-        // URLs, see https://crbug.com/513860.
-        //
-        // We must use the deprecated child-src directive instead of worker-src
-        // since that's not supported yet (as of Chrome 56.)
-        //
-        // "http:" also includes "https:" implictly.
-        // https://www.chromestatus.com/feature/6653486812889088
-        value: "connect-src http:; child-src http:; " +
-               "frame-src http:; object-src http:"
-      });
-      return {responseHeaders: details.responseHeaders};
+      cspMatch = defaultMatcher.matchesAny(urlString, typeMap.CSP, hostname,
+                                           false, null, specificOnly);
+      if (!(cspMatch instanceof BlockingFilter))
+        return;
     }
-  }, {
-    urls: ["http://*/*", "https://*/*"],
-    // We must also intercept script requests since otherwise Web Workers can
-    // be abused to execute scripts for which our Content Security Policy
-    // won't be injected.
-    // https://github.com/gorhill/uBO-Extra/issues/19
-    types: ["main_frame", "sub_frame", "script"]
-  }, ["blocking", "responseHeaders"]);
-}
+
+    FilterNotifier.emit("filter.hitCount", cspMatch, 0, 0, page);
+    devtools.logRequest(page, urlString, "CSP", hostname, false, null,
+                        specificOnly, cspMatch);
+
+    details.responseHeaders.push({
+      name: "Content-Security-Policy",
+      value: cspMatch.csp
+    });
+
+    return {responseHeaders: details.responseHeaders};
+  }
+}, {
+  urls: ["http://*/*", "https://*/*"],
+  types: ["main_frame", "sub_frame"]
+}, ["blocking", "responseHeaders"]);