2 files changed, 13 insertions, 3 deletions
diff --git a/activerecord/lib/active_record/attribute_assignment.rb b/activerecord/lib/active_record/attribute_assignment.rb
index abc2fa546a..269fc3e381 100644
--- a/activerecord/lib/active_record/attribute_assignment.rb
+++ b/activerecord/lib/active_record/attribute_assignment.rb
@@ -1,11 +1,24 @@
 require 'active_support/concern'
 
 module ActiveRecord
+  ActiveSupport.on_load(:active_record_config) do
+    mattr_accessor :whitelist_attributes, instance_accessor: false
+  end
+
   module AttributeAssignment
     extend ActiveSupport::Concern
     include ActiveModel::MassAssignmentSecurity
 
+    included do
+      attr_accessible(nil) if Model.whitelist_attributes
+    end
+
     module ClassMethods
+      def inherited(child) # :nodoc:
+        child.attr_accessible(nil) if Model.whitelist_attributes
+        super
+      end
+
       private
 
       # The primary key and inheritance column can never be set by mass-assignment for security reasons.
diff --git a/activerecord/lib/active_record/railtie.rb b/activerecord/lib/active_record/railtie.rb
index 6937960e93..bcafcbb76c 100644
--- a/activerecord/lib/active_record/railtie.rb
+++ b/activerecord/lib/active_record/railtie.rb
@@ -68,9 +68,6 @@ module ActiveRecord
 
     initializer "active_record.set_configs" do |app|
       ActiveSupport.on_load(:active_record) do
-        if app.config.active_record.delete(:whitelist_attributes)
-          attr_accessible(nil)
-        end
         app.config.active_record.each do |k,v|
           send "#{k}=", v
         end