authorization with cancancan

app/controllers/users/omniauth_callbacks_controller.rb

@@ -1,6 +1,7 @@
 module Users
   class OmniauthCallbacksController < Devise::OmniauthCallbacksController
     skip_before_filter :verify_authenticity_token
+    skip_authorization_check
 
     User.omniauth_providers.each do |provider|
       define_method(provider) { handle(provider) }