require 'active_support/core_ext/class/attribute' module ActionController #:nodoc: class InvalidAuthenticityToken < ActionControllerError #:nodoc: end # Protecting controller actions from CSRF attacks by ensuring that all forms are coming from the current # web application, not a forged link from another site, is done by embedding a token based on a random # string stored in the session (which an attacker wouldn't know) in all forms and Ajax requests generated # by Rails and then verifying the authenticity of that token in the controller. Only HTML/JavaScript # requests are checked, so this will not protect your XML API (presumably you'll have a different # authentication scheme there anyway). Also, GET requests are not protected as these should be # idempotent anyway. # # This is turned on with the protect_from_forgery method, which will check the token and raise an # ActionController::InvalidAuthenticityToken if it doesn't match what was expected. You can customize the # error message in production by editing public/422.html. A call to this method in ApplicationController is # generated by default in post-Rails 2.0 applications. # # The token parameter is named authenticity_token by default. If you are generating an HTML form # manually (without the use of Rails' form_for, form_tag or other helpers), you have to # include a hidden field named like that and set its value to what is returned by # form_authenticity_token. # # Request forgery protection is disabled by default in test environment. If you are upgrading from Rails # 1.x, add this to config/environments/test.rb: # # # Disable request forgery protection in test environment # config.action_controller.allow_forgery_protection = false # # == Learn more about CSRF (Cross-Site Request Forgery) attacks # # Here are some resources: # * http://isc.sans.org/diary.html?storyid=1750 # * http://en.wikipedia.org/wiki/Cross-site_request_forgery # # Keep in mind, this is NOT a silver-bullet, plug 'n' play, warm security blanket for your rails application. # There are a few guidelines you should follow: # # * Keep your GET requests safe and idempotent. More reading material: # * http://www.xml.com/pub/a/2002/04/24/deviant.html # * http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html#sec9.1.1 # * Make sure the session cookies that Rails creates are non-persistent. Check in Firefox and look # for "Expires: at end of session" # module RequestForgeryProtection extend ActiveSupport::Concern include AbstractController::Helpers included do # Sets the token parameter name for RequestForgery. Calling +protect_from_forgery+ # sets it to :authenticity_token by default. config_accessor :request_forgery_protection_token self.request_forgery_protection_token ||= :authenticity_token # Controls whether request forgergy protection is turned on or not. Turned off by default only in test mode. config_accessor :allow_forgery_protection self.allow_forgery_protection = true if allow_forgery_protection.nil? helper_method :form_authenticity_token helper_method :protect_against_forgery? end module ClassMethods # Turn on request forgery protection. Bear in mind that only non-GET, HTML/JavaScript requests are checked. # # Example: # # class FooController < ApplicationController # protect_from_forgery :except => :index # # # you can disable csrf protection on controller-by-controller basis: # skip_before_filter :verify_authenticity_token # end # # Valid Options: # # * :only/:except - Passed to the before_filter call. Set which actions are verified. def protect_from_forgery(options = {}) self.request_forgery_protection_token ||= :authenticity_token before_filter :verify_authenticity_token, options end end protected def protect_from_forgery(options = {}) self.request_forgery_protection_token ||= :authenticity_token before_filter :verify_authenticity_token, options end # 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) end # Returns true or false if a request is verified. Checks: # # * is the format restricted? By default, only HTML requests are checked. # * 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.forgery_whitelisted? || form_authenticity_token == params[request_forgery_protection_token] end # Sets the token value for the current session. def form_authenticity_token session[:_csrf_token] ||= ActiveSupport::SecureRandom.base64(32) end # The form's authenticity parameter. Override to provide your own. def form_authenticity_param params[request_forgery_protection_token] end def protect_against_forgery? allow_forgery_protection end end end