Properly check if the request is cross domain

Fix CVE-2015-1840

Author: rafaelfranca

src/rails.js

@@ -86,16 +86,14 @@
 
     // Default way to get an element's href. May be overridden at $.rails.href.
     href: function(element) {
-      return element.attr('href');
+      return element[0].href;
     },
 
     // Submits "remote" forms and links with ajax
     handleRemote: function(element) {
-      var method, url, data, elCrossDomain, crossDomain, withCredentials, dataType, options;
+      var method, url, data, withCredentials, dataType, options;
 
       if (rails.fire(element, 'ajax:before')) {
-        elCrossDomain = element.data('cross-domain');
-        crossDomain = elCrossDomain === undefined ? null : elCrossDomain;
         withCredentials = element.data('with-credentials') || null;
         dataType = element.data('type') || ($.ajaxSettings && $.ajaxSettings.dataType);
 
@@ -147,7 +145,7 @@
           error: function(xhr, status, error) {
             element.trigger('ajax:error', [xhr, status, error]);
           },
-          crossDomain: crossDomain
+          crossDomain: rails.isCrossDomain(url)
         };
 
         // There is no withCredentials for IE6-8 when
@@ -167,6 +165,27 @@
       }
     },
 
+    // Determines if the request is a cross domain request.
+    isCrossDomain: function(url) {
+      var originAnchor = document.createElement("a");
+      originAnchor.href = location.href;
+      var urlAnchor = document.createElement("a");
+
+      try {
+        urlAnchor.href = url;
+        // This is a workaround to a IE bug.
+        urlAnchor.href = urlAnchor.href;
+
+        // Make sure that the browser parses the URL and that the protocols and hosts match.
+        return !urlAnchor.protocol || !urlAnchor.host ||
+          (originAnchor.protocol + "//" + originAnchor.host !==
+            urlAnchor.protocol + "//" + urlAnchor.host);
+      } catch (e) {
+        // If there is an error parsing the URL, assume it is crossDomain.
+        return true;
+      }
+    },
+
     // Handles "data-method" on links such as:
     // <a href="/users/5" data-method="delete" rel="nofollow" data-confirm="Are you sure?">Delete</a>
     handleMethod: function(link) {
@@ -178,7 +197,7 @@
         form = $('<form method="post" action="' + href + '"></form>'),
         metadataInput = '<input name="_method" value="' + method + '" type="hidden" />';
 
-      if (csrfParam !== undefined && csrfToken !== undefined) {
+      if (csrfParam !== undefined && csrfToken !== undefined && !rails.isCrossDomain(href)) {
         metadataInput += '<input name="' + csrfParam + '" value="' + csrfToken + '" type="hidden" />';
       }
 

test/public/test/call-remote-callbacks.js

@@ -64,20 +64,6 @@ asyncTest('modifying data("type") with "ajax:before" requests new dataType in re
   });
 });
 
-asyncTest('setting data("cross-domain",true) with "ajax:before" uses new setting in request', 2, function(){
-  $('form[data-remote]').data('cross-domain',false)
-    .bind('ajax:before', function() {
-      var form = $(this);
-      form.data('cross-domain',true);
-    });
-
-  submit(function(form) {
-    form.bind('ajax:beforeSend', function(e, xhr, settings) {
-      equal(settings.crossDomain, true, 'setting modified in ajax:before should have forced cross-domain request');
-    });
-  });
-});
-
 asyncTest('setting data("with-credentials",true) with "ajax:before" uses new setting in request', 2, function(){
   $('form[data-remote]').data('with-credentials',false)
     .bind('ajax:before', function() {

test/public/test/call-remote.js

@@ -122,22 +122,6 @@ asyncTest('sends CSRF token in custom header', 1, function() {
   });
 });
 
-asyncTest('does not send CSRF token in custom header if crossDomain', 1, function() {
-  buildForm({ 'data-cross-domain': 'true' });
-  $('#qunit-fixture').append('<meta name="csrf-token" content="cf50faa3fe97702ca1ae" />');
-
-  // Manually set request header to be XHR, since setting crossDomain: true in .ajax()
-  // causes jQuery to skip setting the request header, to prevent our test/server.rb from
-  // raising an an error (when request.xhr? is false).
-  $('#qunit-fixture').find('form').bind('ajax:beforeSend', function(e, xhr) {
-    xhr.setRequestHeader('X-Requested-With', "XMLHttpRequest");
-  });
-
-  submit(function(e, data, status, xhr) {
-    equal(data.HTTP_X_CSRF_TOKEN, undefined, 'X-CSRF-Token header should NOT be sent');
-  });
-});
-
 asyncTest('intelligently guesses crossDomain behavior when target URL is a different domain', 1, function(e, xhr) {
 
   // Don't set data-cross-domain here, just set action to be a different domain than localhost
@@ -156,20 +140,4 @@ asyncTest('intelligently guesses crossDomain behavior when target URL is a diffe
 
   setTimeout(function() { start(); }, 13);
 });
-
-asyncTest('does not set crossDomain if explicitly set to false on element', 1, function() {
-  buildForm({ action: 'http://www.alfajango.com', 'data-cross-domain': false });
-  $('#qunit-fixture').append('<meta name="csrf-token" content="cf50faa3fe97702ca1ae" />');
-
-  $('#qunit-fixture').find('form')
-    .bind('ajax:beforeSend', function(e, xhr, settings) {
-      equal(settings.crossDomain, false, 'crossDomain should be set to false');
-      // prevent request from actually getting sent off-domain
-      return false;
-    })
-    .trigger('submit');
-
-  setTimeout(function() { start(); }, 13);
-});
-
 })();

test/public/test/data-method.js

@@ -46,4 +46,30 @@ asyncTest('link "target" should be carried over to generated form', 1, function(
   });
 });
 
+asyncTest('link with "data-method" and cross origin', 1, function() {
+  var data = {};
+
+  $('#qunit-fixture')
+    .append('<meta name="csrf-param" content="authenticity_token"/>')
+    .append('<meta name="csrf-token" content="cf50faa3fe97702ca1ae"/>');
+
+  $(document).on('submit', 'form', function(e) {
+    $(e.currentTarget).serializeArray().map(function(item) {
+      data[item.name] = item.value;
+    });
+
+    return false;
+  });
+
+  var link = $('#qunit-fixture').find('a');
+
+  link.attr('href', 'http://www.alfajango.com');
+
+  link.trigger('click');
+
+  start();
+
+  notEqual(data.authenticity_token, 'cf50faa3fe97702ca1ae');
+});
+
 })();

test/public/test/override.js

@@ -32,7 +32,7 @@ asyncTest("the getter for an element's href is overridable", 1, function() {
 
 asyncTest("the getter for an element's href works normally if not overridden", 1, function() {
   $.rails.ajax = function(options) {
-    equal('/real/href', options.url);
+    equal(location.protocol + '//' + location.host + '/real/href', options.url);
   }
   $.rails.handleRemote($('#qunit-fixture').find('a'));
   start();