Module: ActionController::RequestForgeryProtection
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Included In:
Base ,
::ActionView::TestCase::TestController ,
Rails::ApplicationController,
::Rails::HealthController ,
Rails::InfoController,
Rails::MailersController,
Rails::WelcomeController
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Defined in: | actionpack/lib/action_controller/metal/request_forgery_protection.rb |
Overview
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. All requests are checked except GET requests as these should be idempotent. Keep in mind that all session-oriented requests are CSRF protected by default, including JavaScript and HTML requests.
Since HTML and JavaScript requests are typically made from the browser, we need to ensure to verify request authenticity for the web browser. We can use session-oriented authentication for these types of requests, by using the protect_from_forgery
method in our controllers.
GET requests are not protected since they don’t have side effects like writing to the database and don’t leak sensitive information. JavaScript requests are an exception: a third-party site can use a <script> tag to reference a JavaScript URL on your site. When your JavaScript response loads on their site, it executes. With carefully crafted JavaScript on their end, sensitive data in your JavaScript response may be extracted. To prevent this, only XmlHttpRequest (known as XHR or Ajax) requests are allowed to make requests for JavaScript responses.
Subclasses of Base
are protected by default with the :exception
strategy, which raises an InvalidAuthenticityToken
error on unverified requests.
APIs may want to disable this behavior since they are typically designed to be state-less: that is, the request API
client handles the session instead of Rails. One way to achieve this is to use the :null_session
strategy instead, which allows unverified requests to be handled, but with an empty session:
class ApplicationController < ActionController::Base
protect_from_forgery with: :null_session
end
Note that API
only applications don’t include this module or a session middleware by default, and so don’t require CSRF protection to be configured.
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}.
Constant Summary
-
AUTHENTICITY_TOKEN_LENGTH =
# File 'actionpack/lib/action_controller/metal/request_forgery_protection.rb', line 43532
-
CSRF_TOKEN =
# File 'actionpack/lib/action_controller/metal/request_forgery_protection.rb', line 60"action_controller.csrf_token"
-
GLOBAL_CSRF_TOKEN_IDENTIFIER =
private
# File 'actionpack/lib/action_controller/metal/request_forgery_protection.rb', line 564"!real_csrf_token"
-
NULL_ORIGIN_MESSAGE =
# File 'actionpack/lib/action_controller/metal/request_forgery_protection.rb', line 600<<~MSG The browser returned a 'null' origin for a request with origin-based forgery protection turned on. This usually means you have the 'no-referrer' Referrer-Policy header enabled, or that the request came from a site that refused to give its origin. This makes it impossible for Rails to verify the source of the requests. Likely the best solution is to change your referrer policy to something less strict like same-origin or strict-origin. If you cannot change the referrer policy, you can disable origin checking with the Rails.application.config.action_controller.forgery_protection_origin_check setting. MSG
::ActiveSupport::Callbacks
- Included
::AbstractController::Callbacks
- Attributes & Methods
- .raise_on_missing_callback_actions (also: #raise_on_missing_callback_actions) rw
- #raise_on_missing_callback_actions rw
::AbstractController::Helpers
- Attributes & Methods
Class Method Summary
::ActiveSupport::DescendantsTracker
- self
descendants | See additional method definition at line 104. |
subclasses | See additional method definition at line 100. |
::ActiveSupport::Concern
- Extended
class_methods | Define class methods from given block. |
included | Evaluate given block in context of base class, so that you can write class macros here. |
prepended | Evaluate given block in context of base class, so that you can write class macros here. |
Instance Attribute Summary
-
#any_authenticity_token_valid? ⇒ Boolean
readonly
private
Checks if any of the authenticity tokens from the request are valid.
-
#marked_for_same_origin_verification? ⇒ Boolean
readonly
private
If the #verify_authenticity_token before_action ran, verify that JavaScript responses are only served to same-origin GET requests.
-
#non_xhr_javascript_response? ⇒ Boolean
readonly
private
Check for cross-origin JavaScript responses.
-
#protect_against_forgery? ⇒ Boolean
readonly
private
Checks if the controller allows forgery protection.
-
#valid_request_origin? ⇒ Boolean
readonly
private
Checks if the request originated from the same origin by looking at the Origin header.
-
#verified_request? ⇒ Boolean
readonly
private
Returns true or false if a request is verified.
::AbstractController::Callbacks
- Included
Instance Method Summary
- #commit_csrf_token(request)
- #initialize
- #reset_csrf_token(request)
- #compare_with_global_token(token, session = nil) private
- #compare_with_real_token(token, session = nil) private
- #csrf_token_hmac(session, identifier) private
-
#form_authenticity_param
private
The form’s authenticity parameter.
-
#form_authenticity_token(form_options: {})
private
Creates the authenticity token for the current request.
- #global_csrf_token(session = nil) private
- #handle_unverified_request private
-
#mark_for_same_origin_verification!
private
GET requests are checked for cross-origin JavaScript after rendering.
- #mask_token(raw_token) private
- #normalize_action_path(action_path) private
- #per_form_csrf_token(session, action_path, method) private
- #real_csrf_token(_session = nil) private
-
#request_authenticity_tokens
private
Possible authenticity tokens sent in the request.
- #unmask_token(masked_token) private
-
#valid_authenticity_token?(session, encoded_masked_token) ⇒ Boolean
private
Checks the client’s masked token to see if it matches the session token.
- #valid_per_form_csrf_token?(token, session = nil) ⇒ Boolean private
-
#verify_authenticity_token
private
The actual before_action that is used to verify the CSRF token.
-
#verify_same_origin_request
private
If #verify_authenticity_token was run (indicating that we have forgery protection enabled for this request) then also verify that we aren’t serving an unauthorized cross-origin response.
- #xor_byte_strings(s1, s2) private
::ActiveSupport::Callbacks
- Included
#run_callbacks | Runs the callbacks for the given event. |
::AbstractController::Helpers
- Included
DSL Calls
included
[ GitHub ]67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103
# File 'actionpack/lib/action_controller/metal/request_forgery_protection.rb', line 67
included do # Sets the token parameter name for RequestForgery. Calling protect_from_forgery # sets it to <tt>:authenticity_token</tt> by default. config_accessor :request_forgery_protection_token self.request_forgery_protection_token ||= :authenticity_token # Holds the class which implements the request forgery protection. config_accessor :forgery_protection_strategy self.forgery_protection_strategy = nil # 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? # Controls whether a CSRF failure logs a warning. On by default. config_accessor :log_warning_on_csrf_failure self.log_warning_on_csrf_failure = true # Controls whether the Origin header is checked in addition to the CSRF token. config_accessor :forgery_protection_origin_check self.forgery_protection_origin_check = false # Controls whether form-action/method specific CSRF tokens are used. config_accessor :per_form_csrf_tokens self.per_form_csrf_tokens = false # Controls whether forgery protection is enabled by default. config_accessor :default_protect_from_forgery self.default_protect_from_forgery = false # The strategy to use for storing and retrieving CSRF tokens. config_accessor :csrf_token_storage_strategy self.csrf_token_storage_strategy = SessionStore.new helper_method :form_authenticity_token helper_method :protect_against_forgery? end
Class Attribute Details
._helper_methods (rw)
[ GitHub ]# File 'actionpack/lib/abstract_controller/helpers.rb', line 12
class_attribute :_helper_methods, default: Array.new
._helper_methods? ⇒ Boolean
(rw)
[ GitHub ]
# File 'actionpack/lib/abstract_controller/helpers.rb', line 12
class_attribute :_helper_methods, default: Array.new
.raise_on_missing_callback_actions (rw) Also known as: #raise_on_missing_callback_actions
[ GitHub ]# File 'actionpack/lib/abstract_controller/callbacks.rb', line 36
mattr_accessor :raise_on_missing_callback_actions, default: false
Instance Attribute Details
#_helper_methods (rw)
[ GitHub ]# File 'actionpack/lib/abstract_controller/helpers.rb', line 12
class_attribute :_helper_methods, default: Array.new
#_helper_methods? ⇒ Boolean
(rw)
[ GitHub ]
# File 'actionpack/lib/abstract_controller/helpers.rb', line 12
class_attribute :_helper_methods, default: Array.new
#any_authenticity_token_valid? ⇒ Boolean
(readonly, private)
Checks if any of the authenticity tokens from the request are valid.
# File 'actionpack/lib/action_controller/metal/request_forgery_protection.rb', line 448
def any_authenticity_token_valid? # :doc: request_authenticity_tokens.any? do |token| valid_authenticity_token?(session, token) end end
#marked_for_same_origin_verification? ⇒ Boolean
(readonly, private)
If the #verify_authenticity_token before_action ran, verify that JavaScript responses are only served to same-origin GET requests.
# File 'actionpack/lib/action_controller/metal/request_forgery_protection.rb', line 426
def marked_for_same_origin_verification? # :doc: @marked_for_same_origin_verification ||= false end
#non_xhr_javascript_response? ⇒ Boolean
(readonly, private)
Check for cross-origin JavaScript responses.
# File 'actionpack/lib/action_controller/metal/request_forgery_protection.rb', line 431
def non_xhr_javascript_response? # :doc: %r(\A(?:text|application)/javascript).match?(media_type) && !request.xhr? end
#protect_against_forgery? ⇒ Boolean
(readonly, private)
Checks if the controller allows forgery protection.
# File 'actionpack/lib/action_controller/metal/request_forgery_protection.rb', line 596
def protect_against_forgery? # :doc: allow_forgery_protection && (!session.respond_to?(:enabled?) || session.enabled?) end
#raise_on_missing_callback_actions (rw)
[ GitHub ]# File 'actionpack/lib/abstract_controller/callbacks.rb', line 36
mattr_accessor :raise_on_missing_callback_actions, default: false
#valid_request_origin? ⇒ Boolean
(readonly, private)
Checks if the request originated from the same origin by looking at the Origin header.
# File 'actionpack/lib/action_controller/metal/request_forgery_protection.rb', line 611
def valid_request_origin? # :doc: if forgery_protection_origin_check # We accept blank origin headers because some user agents don't send it. raise InvalidAuthenticityToken, NULL_ORIGIN_MESSAGE if request.origin == "null" request.origin.nil? || request.origin == request.base_url else true end end
#verified_request? ⇒ Boolean
(readonly, private)
Returns true or false if a request is verified. Checks:
-
Is it a GET or HEAD 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?
# File 'actionpack/lib/action_controller/metal/request_forgery_protection.rb', line 442
def verified_request? # :doc: !protect_against_forgery? || request.get? || request.head? || (valid_request_origin? && any_authenticity_token_valid?) end
Instance Method Details
#commit_csrf_token(request)
[ GitHub ]# File 'actionpack/lib/action_controller/metal/request_forgery_protection.rb', line 355
def commit_csrf_token(request) # :doc: csrf_token = request.env[CSRF_TOKEN] csrf_token_storage_strategy.store(request, csrf_token) unless csrf_token.nil? end
#compare_with_global_token(token, session = nil) (private)
[ GitHub ]# File 'actionpack/lib/action_controller/metal/request_forgery_protection.rb', line 534
def compare_with_global_token(token, session = nil) # :doc: ActiveSupport::SecurityUtils.fixed_length_secure_compare(token, global_csrf_token(session)) end
#compare_with_real_token(token, session = nil) (private)
[ GitHub ]# File 'actionpack/lib/action_controller/metal/request_forgery_protection.rb', line 530
def compare_with_real_token(token, session = nil) # :doc: ActiveSupport::SecurityUtils.fixed_length_secure_compare(token, real_csrf_token(session)) end
#csrf_token_hmac(session, identifier) (private)
[ GitHub ]# File 'actionpack/lib/action_controller/metal/request_forgery_protection.rb', line 571
def csrf_token_hmac(session, identifier) # :doc: OpenSSL::HMAC.digest( OpenSSL::Digest::SHA256.new, real_csrf_token(session), identifier ) end
#form_authenticity_param (private)
The form’s authenticity parameter. Override to provide your own.
# File 'actionpack/lib/action_controller/metal/request_forgery_protection.rb', line 591
def form_authenticity_param # :doc: params[request_forgery_protection_token] end
#form_authenticity_token(form_options: {}) (private)
Creates the authenticity token for the current request.
# File 'actionpack/lib/action_controller/metal/request_forgery_protection.rb', line 460
def form_authenticity_token(form_options: {}) # :doc: masked_authenticity_token(form_options: ) end
#global_csrf_token(session = nil) (private)
[ GitHub ]# File 'actionpack/lib/action_controller/metal/request_forgery_protection.rb', line 567
def global_csrf_token(session = nil) # :doc: csrf_token_hmac(session, GLOBAL_CSRF_TOKEN_IDENTIFIER) end
#handle_unverified_request (private)
[ GitHub ]# File 'actionpack/lib/action_controller/metal/request_forgery_protection.rb', line 381
def handle_unverified_request # :doc: protection_strategy = forgery_protection_strategy.new(self) if protection_strategy.respond_to?(: ) protection_strategy. = end protection_strategy.handle_unverified_request end
#initialize
[ GitHub ]# File 'actionpack/lib/action_controller/metal/request_forgery_protection.rb', line 345
def initialize(...) super @marked_for_same_origin_verification = nil end
#mark_for_same_origin_verification! (private)
GET requests are checked for cross-origin JavaScript after rendering.
# File 'actionpack/lib/action_controller/metal/request_forgery_protection.rb', line 420
def mark_for_same_origin_verification! # :doc: @marked_for_same_origin_verification = request.get? end
#mask_token(raw_token) (private)
[ GitHub ]# File 'actionpack/lib/action_controller/metal/request_forgery_protection.rb', line 523
def mask_token(raw_token) # :doc: one_time_pad = SecureRandom.random_bytes(AUTHENTICITY_TOKEN_LENGTH) encrypted_csrf_token = xor_byte_strings(one_time_pad, raw_token) masked_token = one_time_pad + encrypted_csrf_token encode_csrf_token(masked_token) end
#normalize_action_path(action_path) (private)
[ GitHub ]# File 'actionpack/lib/action_controller/metal/request_forgery_protection.rb', line 621
def normalize_action_path(action_path) # :doc: uri = URI.parse(action_path) uri.path.chomp("/") end
#per_form_csrf_token(session, action_path, method) (private)
[ GitHub ]# File 'actionpack/lib/action_controller/metal/request_forgery_protection.rb', line 560
def per_form_csrf_token(session, action_path, method) # :doc: csrf_token_hmac(session, [action_path, method.downcase].join("#")) end
#real_csrf_token(_session = nil) (private)
[ GitHub ]# File 'actionpack/lib/action_controller/metal/request_forgery_protection.rb', line 552
def real_csrf_token(_session = nil) # :doc: csrf_token = request.env.fetch(CSRF_TOKEN) do request.env[CSRF_TOKEN] = csrf_token_storage_strategy.fetch(request) || generate_csrf_token end decode_csrf_token(csrf_token) end
#request_authenticity_tokens (private)
Possible authenticity tokens sent in the request.
# File 'actionpack/lib/action_controller/metal/request_forgery_protection.rb', line 455
def request_authenticity_tokens # :doc: [form_authenticity_param, request.x_csrf_token] end
#reset_csrf_token(request)
[ GitHub ]# File 'actionpack/lib/action_controller/metal/request_forgery_protection.rb', line 350
def reset_csrf_token(request) # :doc: request.env.delete(CSRF_TOKEN) csrf_token_storage_strategy.reset(request) end
#unmask_token(masked_token) (private)
[ GitHub ]# File 'actionpack/lib/action_controller/metal/request_forgery_protection.rb', line 515
def unmask_token(masked_token) # :doc: # Split the token into the one-time pad and the encrypted # value and decrypt it. one_time_pad = masked_token[0...AUTHENTICITY_TOKEN_LENGTH] encrypted_csrf_token = masked_token[AUTHENTICITY_TOKEN_LENGTH..-1] xor_byte_strings(one_time_pad, encrypted_csrf_token) end
#valid_authenticity_token?(session, encoded_masked_token) ⇒ Boolean
(private)
Checks the client’s masked token to see if it matches the session token. Essentially the inverse of #masked_authenticity_token.
# File 'actionpack/lib/action_controller/metal/request_forgery_protection.rb', line 483
def valid_authenticity_token?(session, encoded_masked_token) # :doc: if encoded_masked_token.nil? || encoded_masked_token.empty? || !encoded_masked_token.is_a?(String) return false end begin masked_token = decode_csrf_token(encoded_masked_token) rescue ArgumentError # encoded_masked_token is invalid Base64 return false end # See if it's actually a masked token or not. In order to # deploy this code, we should be able to handle any unmasked # tokens that we've issued without error. if masked_token.length == AUTHENTICITY_TOKEN_LENGTH # This is actually an unmasked token. This is expected if # you have just upgraded to masked tokens, but should stop # happening shortly after installing this gem. compare_with_real_token masked_token elsif masked_token.length == AUTHENTICITY_TOKEN_LENGTH * 2 csrf_token = unmask_token(masked_token) compare_with_global_token(csrf_token) || compare_with_real_token(csrf_token) || valid_per_form_csrf_token?(csrf_token) else false # Token is malformed. end end
#valid_per_form_csrf_token?(token, session = nil) ⇒ Boolean
(private)
# File 'actionpack/lib/action_controller/metal/request_forgery_protection.rb', line 538
def valid_per_form_csrf_token?(token, session = nil) # :doc: if per_form_csrf_tokens correct_token = per_form_csrf_token( session, request.path.chomp("/"), request.request_method ) ActiveSupport::SecurityUtils.fixed_length_secure_compare(token, correct_token) else false end end
#verify_authenticity_token (private)
The actual before_action that is used to verify the CSRF token. Don’t override this directly. Provide your own forgery protection strategy instead. If you override, you’ll disable same-origin <script>
verification.
Lean on the protect_from_forgery declaration to mark which actions are due for same-origin request verification. If protect_from_forgery is enabled on an action, this before_action flags its after_action to verify that JavaScript responses are for XHR requests, ensuring they follow the browser’s same-origin policy.
# File 'actionpack/lib/action_controller/metal/request_forgery_protection.rb', line 371
def verify_authenticity_token # :doc: mark_for_same_origin_verification! if !verified_request? logger.warn if logger && log_warning_on_csrf_failure handle_unverified_request end end
#verify_same_origin_request (private)
If #verify_authenticity_token was run (indicating that we have forgery protection enabled for this request) then also verify that we aren’t serving an unauthorized cross-origin response.
# File 'actionpack/lib/action_controller/metal/request_forgery_protection.rb', line 410
def verify_same_origin_request # :doc: if marked_for_same_origin_verification? && non_xhr_javascript_response? if logger && log_warning_on_csrf_failure logger.warn CROSS_ORIGIN_JAVASCRIPT_WARNING end raise ActionController::InvalidCrossOriginRequest, CROSS_ORIGIN_JAVASCRIPT_WARNING end end
#xor_byte_strings(s1, s2) (private)
[ GitHub ]# File 'actionpack/lib/action_controller/metal/request_forgery_protection.rb', line 579
def xor_byte_strings(s1, s2) # :doc: s2 = s2.dup size = s1.bytesize i = 0 while i < size s2.setbyte(i, s1.getbyte(i) ^ s2.getbyte(i)) i += 1 end s2 end