[$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");
+
+browser.webRequest.onHeadersReceived.addListener(details =>
 {
-  const {defaultMatcher} = require("matcher");
-  const {BlockingFilter, RegExpFilter} = require("filterClasses");
-  const {getDecodedHostname} = require("url");
-  const {checkWhitelisted} = require("whitelisting");
+  // Chrome seems to sometimes give the response type of "xmlhttprequest"
+  // instead of "main_frame", but when it does the tabId is always -1 and
+  // the URL matches the initiator's URL (once normalised).
+  // https://bugs.chromium.org/p/chromium/issues/detail?id=805649

[kzar, 2018/01/26 18:12:37]

This bug is also potentially relevant for our ext/background.js code, I'm going
to look into that next week.

+  if (details.type == "xmlhttprequest" &&
+      (details.tabId > -1 || details.initiator &&
+       details.url != new URL(details.initiator).toString()))
+  {
+    return;
+  }
 
-  browser.webRequest.onHeadersReceived.addListener(details =>
+  // To avoid an extra matchesAny for the common case let's assume no
+  // $genericblock filters apply when searching for a matching $csp filter,
+  // we double check later when necessary.
+  let specificOnly = false;
+
+  let url = new URL(details.url);
+  let hostname = getDecodedHostname(url);
+  let cspMatch = defaultMatcher.matchesAny(
+    details.url,
+    RegExpFilter.typeMap.CSP,
+    hostname, false, null, specificOnly
+  );
+
+  if (cspMatch instanceof BlockingFilter)
   {
-    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)))
+    if (details.tabId > -1)
     {
-      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};
+      let page = new ext.Page({id: details.tabId, url: details.url});
+      let frame = ext.getFrame(details.tabId, details.frameId);
+
+      if (checkWhitelisted(page, frame, RegExpFilter.typeMap.DOCUMENT |
+                                          RegExpFilter.typeMap.CSP))
+      {
+        return;
+      }
+
+      // We pay the price now for skipping the specificOnly check earlier, we
+      // must check again for a CSP filter, this time making sure it's specific.
+      specificOnly = !!checkWhitelisted(page, frame,
+                                        RegExpFilter.typeMap.GENERICBLOCK);
+      if (specificOnly)
+      {
+        cspMatch = defaultMatcher.matchesAny(
+          details.url,
+          RegExpFilter.typeMap.CSP,
+          hostname, false, null, specificOnly
+        );
+        if (!(cspMatch instanceof BlockingFilter))
+          return;
+      }
+
+      FilterNotifier.emit("filter.hitCount", cspMatch, 0, 0, page);
     }
-  }, {
-    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"]);
-}
+    // If we don't know the associated tab we'll have to check that if the URL
+    // is whitelisted manually. Things like $sitekey whitelisting and filter hit
+    // logging won't work, but it's the best we can do.
+    else if (defaultMatcher.whitelist.matchesAny(stringifyURL(url),
+                                                 RegExpFilter.typeMap.DOCUMENT |
+                                                   RegExpFilter.typeMap.CSP,
+                                                 hostname))
+    {
+      return;
+    }
+
+    details.responseHeaders.push({
+      name: "Content-Security-Policy",
+      value: cspMatch.csp
+    });
+
+    return {responseHeaders: details.responseHeaders};
+  }
+}, {
+  urls: ["http://*/*", "https://*/*"],
+  types: ["main_frame", "sub_frame", "xmlhttprequest"]
+}, ["blocking", "responseHeaders"]);