require 'rack/session/abstract/id' require 'action_controller/metal/exceptions' module ActionController #:nodoc: class InvalidAuthenticityToken < ActionControllerError #:nodoc: end # Controller actions are protected from Cross-Site Request Forgery (CSRF) attacks # by including a token in the rendered html for your application. This token is # stored as a random string in the session, to which an attacker does not have # access. When a request reaches your application, \Rails verifies the received # token with the token in the session. Only HTML and 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. # # It's important to remember that XML or JSON requests are also affected and if # you're building an API you'll need something like: # # class ApplicationController < ActionController::Base # protect_from_forgery # skip_before_action :verify_authenticity_token, if: :json_request? # # protected # # def json_request? # request.format.json? # end # end # # CSRF protection is turned on with the protect_from_forgery method, # which checks the token and resets the session if it doesn't match what was expected. # A call to this method is generated for new \Rails applications by default. # # The token parameter is named authenticity_token by default. The name and # value of this token must be added to every layout that renders forms by including # csrf_meta_tags in the html +head+. # # Learn more about CSRF attacks and securing your application in the # {Ruby on Rails Security Guide}[http://guides.rubyonrails.org/security.html]. module RequestForgeryProtection extend ActiveSupport::Concern include AbstractController::Helpers include AbstractController::Callbacks 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 forgery 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. # # class FooController < ApplicationController # protect_from_forgery except: :index # # You can disable csrf protection on controller-by-controller basis: # # skip_before_action :verify_authenticity_token # # It can also be disabled for specific controller actions: # # skip_before_action :verify_authenticity_token, except: [:create] # # Valid Options: # # * :only/:except - Passed to the before_action call. Set which actions are verified. # * :with - Set the method to handle unverified request. # # Valid unverified request handling methods are: # * :exception - Raises ActionController::InvalidAuthenticityToken exception. # * :reset_session - Resets the session. # * :null_session - Provides an empty session during request but doesn't reset it completely. Used as default if :with option is not specified. def protect_from_forgery(options = {}) include protection_method_module(options[:with] || :null_session) self.request_forgery_protection_token ||= :authenticity_token prepend_before_action :verify_authenticity_token, options end private def protection_method_module(name) ActionController::RequestForgeryProtection::ProtectionMethods.const_get(name.to_s.classify) rescue NameError raise ArgumentError, 'Invalid request forgery protection method, use :null_session, :exception, or :reset_session' end end module ProtectionMethods module NullSession protected # This is the method that defines the application behavior when a request is found to be unverified. def handle_unverified_request request.session = NullSessionHash.new request.env['action_dispatch.request.flash_hash'] = nil request.env['rack.session.options'] = { skip: true } request.env['action_dispatch.cookies'] = NullCookieJar.build(request) end class NullSessionHash < Rack::Session::Abstract::SessionHash #:nodoc: def initialize super(nil, nil) @loaded = true end def exists? true end end class NullCookieJar < ActionDispatch::Cookies::CookieJar #:nodoc: def self.build(request) key_generator = request.env[ActionDispatch::Cookies::GENERATOR_KEY] host = request.host secure = request.ssl? new(key_generator, host, secure) end def write(*) # nothing end end end module ResetSession protected def handle_unverified_request reset_session end end module Exception protected def handle_unverified_request raise ActionController::InvalidAuthenticityToken end end end protected # The actual before_action that is used. Modify this to change how you handle unverified requests. def verify_authenticity_token unless verified_request? logger.warn "Can't verify CSRF token authenticity" if logger handle_unverified_request end end # Returns true or false if a request is verified. Checks: # # * is it a GET request? Gets should be safe and idempotent # * Does the form_authenticity_token match the given token value from the params? # * Does the X-CSRF-Token header match the form_authenticity_token def verified_request? !protect_against_forgery? || request.get? || form_authenticity_token == params[request_forgery_protection_token] || form_authenticity_token == request.headers['X-CSRF-Token'] end # Sets the token value for the current session. def form_authenticity_token session[:_csrf_token] ||= 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