From 0fb6347bdc2ca91e012c222d92d59e90716e75ec Mon Sep 17 00:00:00 2001

From: Michael Koziarski <michael@koziarski.com>

Date: Mon, 17 Jan 2011 14:12:29 +1300

Subject: [PATCH 2/2] Change the CSRF whitelisting to only apply to get requests

Unfortunately the previous method of browser detection and XHR whitelisting is unable to prevent requests issued from some Flash animations and Java applets.  To ease the work required to include the CSRF token in ajax requests rails now supports providing the token in a custom http header:

 X-CSRF-Token: ...

This fixes CVE-2011-0447

---

 .../request_forgery_protection.rb                  |   15 +-

 actionpack/lib/action_view/helpers.rb              |    2 +

 actionpack/lib/action_view/helpers/csrf_helper.rb  |   14 ++

 .../controller/request_forgery_protection_test.rb  |  216 +++++++++-----------

 4 files changed, 117 insertions(+), 130 deletions(-)

 create mode 100644 actionpack/lib/action_view/helpers/csrf_helper.rb

diff --git a/actionpack/lib/action_controller/request_forgery_protection.rb b/actionpack/lib/action_controller/request_forgery_protection.rb

index 24821ff..0030857 100644

--- a/actionpack/lib/action_controller/request_forgery_protection.rb

+++ b/actionpack/lib/action_controller/request_forgery_protection.rb

@@ -76,7 +76,11 @@ module ActionController #:nodoc:

     protected

       # The actual before_filter that is used.  Modify this to change how you handle unverified requests.

       def verify_authenticity_token

-        verified_request? || raise(ActionController::InvalidAuthenticityToken)

+        verified_request? || handle_unverified_request

+      end

+

+      def handle_unverified_request

+        reset_session

       end

       # Returns true or false if a request is verified.  Checks:

@@ -85,11 +89,10 @@ module ActionController #:nodoc:

       # * is it a GET request?  Gets should be safe and idempotent

       # * Does the form_authenticity_token match the given token value from the params?

       def verified_request?

-        !protect_against_forgery?     ||

-          request.method == :get      ||

-          request.xhr?                ||

-          !verifiable_request_format? ||

-          form_authenticity_token == form_authenticity_param

+        !protect_against_forgery?                            ||

+          request.get?                                       ||

+          form_authenticity_token == form_authenticity_param ||

+          form_authenticity_token == request.headers['X-CSRF-Token']

       end

       def form_authenticity_param

diff --git a/actionpack/lib/action_view/helpers.rb b/actionpack/lib/action_view/helpers.rb

index cea894d..debd2e7 100644

--- a/actionpack/lib/action_view/helpers.rb

+++ b/actionpack/lib/action_view/helpers.rb

@@ -6,6 +6,7 @@ module ActionView #:nodoc:

     autoload :BenchmarkHelper, 'action_view/helpers/benchmark_helper'

     autoload :CacheHelper, 'action_view/helpers/cache_helper'

     autoload :CaptureHelper, 'action_view/helpers/capture_helper'

+    autoload :CsrfHelper, 'action_view/helpers/csrf_helper'

     autoload :DateHelper, 'action_view/helpers/date_helper'

     autoload :DebugHelper, 'action_view/helpers/debug_helper'

     autoload :FormHelper, 'action_view/helpers/form_helper'

@@ -38,6 +39,7 @@ module ActionView #:nodoc:

     include BenchmarkHelper

     include CacheHelper

     include CaptureHelper

+    include CsrfHelper

     include DateHelper

     include DebugHelper

     include FormHelper

diff --git a/actionpack/lib/action_view/helpers/csrf_helper.rb b/actionpack/lib/action_view/helpers/csrf_helper.rb

new file mode 100644

index 0000000..e0e6c9a

--- /dev/null

+++ b/actionpack/lib/action_view/helpers/csrf_helper.rb

@@ -0,0 +1,14 @@

+module ActionView

+  # = Action View CSRF Helper

+  module Helpers

+    module CsrfHelper

+      # Returns a meta tag with the cross-site request forgery protection token

+      # for forms to use. Place this in your head.

+      def csrf_meta_tag

+        if protect_against_forgery?

+          %(<meta name="csrf-param" content="#{h(request_forgery_protection_token)}"/>\n<meta name="csrf-token" content="#{h(form_authenticity_token)}"/>)

+        end

+      end

+    end

+  end

+end

diff --git a/actionpack/test/controller/request_forgery_protection_test.rb b/actionpack/test/controller/request_forgery_protection_test.rb

index c6ad4b9..7502905 100644

--- a/actionpack/test/controller/request_forgery_protection_test.rb

+++ b/actionpack/test/controller/request_forgery_protection_test.rb

@@ -23,6 +23,10 @@ module RequestForgeryProtectionActions

     render :text => 'pwn'

   end

+  def meta

+    render :inline => "<%= csrf_meta_tag %>"

+  end

+

   def rescue_action(e) raise e end

 end

@@ -32,6 +36,16 @@ class RequestForgeryProtectionController < ActionController::Base

   protect_from_forgery :only => :index

 end

+class RequestForgeryProtectionControllerUsingOldBehaviour < ActionController::Base

+  include RequestForgeryProtectionActions

+  protect_from_forgery :only => %w(index meta)

+

+  def handle_unverified_request

+    raise(ActionController::InvalidAuthenticityToken)

+  end

+end

+

+

 class FreeCookieController < RequestForgeryProtectionController

   self.allow_forgery_protection = false

@@ -54,158 +68,92 @@ end

 # common test methods

 module RequestForgeryProtectionTests

-  def teardown

-    ActionController::Base.request_forgery_protection_token = nil

-  end

-  

+  def setup

+    @token      = "cf50faa3fe97702ca1ae"

-  def test_should_render_form_with_token_tag

-     get :index

-     assert_select 'form>div>input[name=?][value=?]', 'authenticity_token', @token

-   end

-

-   def test_should_render_button_to_with_token_tag

-     get :show_button

-     assert_select 'form>div>input[name=?][value=?]', 'authenticity_token', @token

-   end

-

-   def test_should_render_remote_form_with_only_one_token_parameter

-     get :remote_form

-     assert_equal 1, @response.body.scan(@token).size

-   end

-

-   def test_should_allow_get

-     get :index

-     assert_response :success

-   end

-

-   def test_should_allow_post_without_token_on_unsafe_action

-     post :unsafe

-     assert_response :success

-   end

-

-  def test_should_not_allow_html_post_without_token

-    @request.env['CONTENT_TYPE'] = Mime::URL_ENCODED_FORM.to_s

-    assert_raise(ActionController::InvalidAuthenticityToken) { post :index, :format => :html }

+    ActiveSupport::SecureRandom.stubs(:base64).returns(@token)

+    ActionController::Base.request_forgery_protection_token = :authenticity_token

   end

-  def test_should_not_allow_html_put_without_token

-    @request.env['CONTENT_TYPE'] = Mime::URL_ENCODED_FORM.to_s

-    assert_raise(ActionController::InvalidAuthenticityToken) { put :index, :format => :html }

-  end

-  def test_should_not_allow_html_delete_without_token

-    @request.env['CONTENT_TYPE'] = Mime::URL_ENCODED_FORM.to_s

-    assert_raise(ActionController::InvalidAuthenticityToken) { delete :index, :format => :html }

-  end

-

-  def test_should_allow_api_formatted_post_without_token

-    assert_nothing_raised do

-      post :index, :format => 'xml'

+  def test_should_render_form_with_token_tag

+    assert_not_blocked do

+      get :index

     end

+    assert_select 'form>div>input[name=?][value=?]', 'authenticity_token', @token

   end

-  def test_should_not_allow_api_formatted_put_without_token

-    assert_nothing_raised do

-      put :index, :format => 'xml'

+  def test_should_render_button_to_with_token_tag

+    assert_not_blocked do

+      get :show_button

     end

+    assert_select 'form>div>input[name=?][value=?]', 'authenticity_token', @token

   end

-  def test_should_allow_api_formatted_delete_without_token

-    assert_nothing_raised do

-      delete :index, :format => 'xml'

-    end

+  def test_should_allow_get

+    assert_not_blocked { get :index }

   end

-  def test_should_not_allow_api_formatted_post_sent_as_url_encoded_form_without_token

-    assert_raise(ActionController::InvalidAuthenticityToken) do

-      @request.env['CONTENT_TYPE'] = Mime::URL_ENCODED_FORM.to_s

-      post :index, :format => 'xml'

-    end

+  def test_should_allow_post_without_token_on_unsafe_action

+    assert_not_blocked { post :unsafe }

   end

-  def test_should_not_allow_api_formatted_put_sent_as_url_encoded_form_without_token

-    assert_raise(ActionController::InvalidAuthenticityToken) do

-      @request.env['CONTENT_TYPE'] = Mime::URL_ENCODED_FORM.to_s

-      put :index, :format => 'xml'

-    end

+  def test_should_not_allow_post_without_token

+    assert_blocked { post :index }

   end

-  def test_should_not_allow_api_formatted_delete_sent_as_url_encoded_form_without_token

-    assert_raise(ActionController::InvalidAuthenticityToken) do

-      @request.env['CONTENT_TYPE'] = Mime::URL_ENCODED_FORM.to_s

-      delete :index, :format => 'xml'

-    end

+  def test_should_not_allow_post_without_token_irrespective_of_format

+    assert_blocked { post :index, :format=>'xml' }

   end

-  def test_should_not_allow_api_formatted_post_sent_as_multipart_form_without_token

-    assert_raise(ActionController::InvalidAuthenticityToken) do

-      @request.env['CONTENT_TYPE'] = Mime::MULTIPART_FORM.to_s

-      post :index, :format => 'xml'

-    end

+  def test_should_not_allow_put_without_token

+    assert_blocked { put :index }

   end

-  def test_should_not_allow_api_formatted_put_sent_as_multipart_form_without_token

-    assert_raise(ActionController::InvalidAuthenticityToken) do

-      @request.env['CONTENT_TYPE'] = Mime::MULTIPART_FORM.to_s

-      put :index, :format => 'xml'

-    end

+  def test_should_not_allow_delete_without_token

+    assert_blocked { delete :index }

   end

-  def test_should_not_allow_api_formatted_delete_sent_as_multipart_form_without_token

-    assert_raise(ActionController::InvalidAuthenticityToken) do

-      @request.env['CONTENT_TYPE'] = Mime::MULTIPART_FORM.to_s

-      delete :index, :format => 'xml'

-    end

-  end

-  

-  def test_should_allow_xhr_post_without_token

-    assert_nothing_raised { xhr :post, :index }

-  end

-  

-  def test_should_allow_xhr_put_without_token

-    assert_nothing_raised { xhr :put, :index }

-  end

-  

-  def test_should_allow_xhr_delete_without_token

-    assert_nothing_raised { xhr :delete, :index }

+  def test_should_not_allow_xhr_post_without_token

+    assert_blocked { xhr :post, :index }

   end

-  

-  def test_should_allow_xhr_post_with_encoded_form_content_type_without_token

-    @request.env['CONTENT_TYPE'] = Mime::URL_ENCODED_FORM.to_s

-    assert_nothing_raised { xhr :post, :index }

-  end

-  

+

   def test_should_allow_post_with_token

-    post :index, :authenticity_token => @token

-    assert_response :success

+    assert_not_blocked { post :index, :authenticity_token => @token }

   end

   def test_should_allow_put_with_token

-    put :index, :authenticity_token => @token

-    assert_response :success

+    assert_not_blocked { put :index, :authenticity_token => @token }

   end

   def test_should_allow_delete_with_token

-    delete :index, :authenticity_token => @token

-    assert_response :success

+    assert_not_blocked { delete :index, :authenticity_token => @token }

   end

-  def test_should_allow_post_with_xml

-    @request.env['CONTENT_TYPE'] = Mime::XML.to_s

-    post :index, :format => 'xml'

-    assert_response :success

+  def test_should_allow_post_with_token_in_header

+    @request.env['HTTP_X_CSRF_TOKEN'] = @token

+    assert_not_blocked { post :index }

+  end

+

+  def test_should_allow_delete_with_token_in_header

+    @request.env['HTTP_X_CSRF_TOKEN'] = @token

+    assert_not_blocked { delete :index }

   end

-  def test_should_allow_put_with_xml

-    @request.env['CONTENT_TYPE'] = Mime::XML.to_s

-    put :index, :format => 'xml'

+  def test_should_allow_put_with_token_in_header

+    @request.env['HTTP_X_CSRF_TOKEN'] = @token

+    assert_not_blocked { put :index }

+  end

+

+  def assert_blocked

+    session[:something_like_user_id] = 1

+    yield

+    assert_nil session[:something_like_user_id], "session values are still present"

     assert_response :success

   end

-  def test_should_allow_delete_with_xml

-    @request.env['CONTENT_TYPE'] = Mime::XML.to_s

-    delete :index, :format => 'xml'

+  def assert_not_blocked

+    assert_nothing_raised { yield }

     assert_response :success

   end

 end

@@ -214,15 +162,20 @@ end

 class RequestForgeryProtectionControllerTest < ActionController::TestCase

   include RequestForgeryProtectionTests

-  def setup

-    @controller = RequestForgeryProtectionController.new

-    @request    = ActionController::TestRequest.new

-    @request.format = :html

-    @response   = ActionController::TestResponse.new

-    @token      = "cf50faa3fe97702ca1ae"

-    ActiveSupport::SecureRandom.stubs(:base64).returns(@token)

-    ActionController::Base.request_forgery_protection_token = :authenticity_token

+  test 'should emit a csrf-token meta tag' do

+    ActiveSupport::SecureRandom.stubs(:base64).returns(@token + '<=?')

+    get :meta

+    assert_equal %(<meta name="csrf-param" content="authenticity_token"/>\n<meta name="csrf-token" content="cf50faa3fe97702ca1ae<=?"/>), @response.body

+  end

+end

+

+class RequestForgeryProtectionControllerUsingOldBehaviourTest < ActionController::TestCase

+  include RequestForgeryProtectionTests

+  def assert_blocked

+    assert_raises(ActionController::InvalidAuthenticityToken) do

+      yield

+    end

   end

 end

@@ -251,15 +204,30 @@ class FreeCookieControllerTest < ActionController::TestCase

       assert_nothing_raised { send(method, :index)}

     end

   end

+

+  test 'should not emit a csrf-token meta tag' do

+    get :meta

+    assert @response.body.blank?, "#{@response.body.inspect} is not blank"

+  end

 end

+

+

+

+

 class CustomAuthenticityParamControllerTest < ActionController::TestCase

   def setup

+    ActionController::Base.request_forgery_protection_token = :custom_token_name

+    super

+  end

+

+  def teardown

     ActionController::Base.request_forgery_protection_token = :authenticity_token

+    super

   end

   def test_should_allow_custom_token

-    post :index, :authenticity_token => 'foobar'

+    post :index, :custom_token_name => 'foobar'

     assert_response :ok

   end

 end

-- 

1.7.2