diff options
Diffstat (limited to 'actionpack/lib/action_controller/metal')
| -rw-r--r-- | actionpack/lib/action_controller/metal/request_forgery_protection.rb | 72 | ||||
| -rw-r--r-- | actionpack/lib/action_controller/metal/strong_parameters.rb | 87 |
2 files changed, 151 insertions, 8 deletions
diff --git a/actionpack/lib/action_controller/metal/request_forgery_protection.rb b/actionpack/lib/action_controller/metal/request_forgery_protection.rb index 0efa0fb259..a4f376816f 100644 --- a/actionpack/lib/action_controller/metal/request_forgery_protection.rb +++ b/actionpack/lib/action_controller/metal/request_forgery_protection.rb @@ -9,7 +9,7 @@ module ActionController #: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 + # 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, @@ -44,7 +44,7 @@ module ActionController #:nodoc: # # The token parameter is named <tt>authenticity_token</tt> by default. The name and # value of this token must be added to every layout that renders forms by including - # <tt>csrf_meta_tags</tt> in the html +head+. + # <tt>csrf_meta_tags</tt> 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]. @@ -240,6 +240,8 @@ module ActionController #:nodoc: content_type =~ %r(\Atext/javascript) && !request.xhr? end + AUTHENTICITY_TOKEN_LENGTH = 32 + # Returns true or false if a request is verified. Checks: # # * is it a GET or HEAD request? Gets should be safe and idempotent @@ -247,13 +249,73 @@ module ActionController #:nodoc: # * Does the X-CSRF-Token header match the form_authenticity_token def verified_request? !protect_against_forgery? || request.get? || request.head? || - form_authenticity_token == form_authenticity_param || - form_authenticity_token == request.headers['X-CSRF-Token'] + valid_authenticity_token?(session, form_authenticity_param) || + valid_authenticity_token?(session, request.headers['X-CSRF-Token']) end # Sets the token value for the current session. def form_authenticity_token - session[:_csrf_token] ||= SecureRandom.base64(32) + masked_authenticity_token(session) + end + + # Creates a masked version of the authenticity token that varies + # on each request. The masking is used to mitigate SSL attacks + # like BREACH. + def masked_authenticity_token(session) + one_time_pad = SecureRandom.random_bytes(AUTHENTICITY_TOKEN_LENGTH) + encrypted_csrf_token = xor_byte_strings(one_time_pad, real_csrf_token(session)) + masked_token = one_time_pad + encrypted_csrf_token + Base64.strict_encode64(masked_token) + end + + # Checks the client's masked token to see if it matches the + # session token. Essentially the inverse of + # +masked_authenticity_token+. + def valid_authenticity_token?(session, encoded_masked_token) + return false if encoded_masked_token.nil? || encoded_masked_token.empty? + + begin + masked_token = Base64.strict_decode64(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, session + + elsif masked_token.length == AUTHENTICITY_TOKEN_LENGTH * 2 + # 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] + csrf_token = xor_byte_strings(one_time_pad, encrypted_csrf_token) + + compare_with_real_token csrf_token, session + + else + false # Token is malformed + end + end + + def compare_with_real_token(token, session) + # Borrow a constant-time comparison from Rack + Rack::Utils.secure_compare(token, real_csrf_token(session)) + end + + def real_csrf_token(session) + session[:_csrf_token] ||= SecureRandom.base64(AUTHENTICITY_TOKEN_LENGTH) + Base64.strict_decode64(session[:_csrf_token]) + end + + def xor_byte_strings(s1, s2) + s1.bytes.zip(s2.bytes).map { |(c1,c2)| c1 ^ c2 }.pack('c*') end # The form's authenticity parameter. Override to provide your own. diff --git a/actionpack/lib/action_controller/metal/strong_parameters.rb b/actionpack/lib/action_controller/metal/strong_parameters.rb index bc27ecaa20..7038f0997f 100644 --- a/actionpack/lib/action_controller/metal/strong_parameters.rb +++ b/actionpack/lib/action_controller/metal/strong_parameters.rb @@ -141,6 +141,37 @@ module ActionController @permitted = self.class.permit_all_parameters end + # Returns a safe +Hash+ representation of this parameter with all + # unpermitted keys removed. + # + # params = ActionController::Parameters.new({ + # name: 'Senjougahara Hitagi', + # oddity: 'Heavy stone crab' + # }) + # params.to_h # => {} + # + # safe_params = params.permit(:name) + # safe_params.to_h # => {"name"=>"Senjougahara Hitagi"} + def to_h + if permitted? + to_hash + else + slice(*self.class.always_permitted_parameters).permit!.to_h + end + end + + # Convert all hashes in values into parameters, then yield each pair like + # the same way as <tt>Hash#each_pair</tt> + def each_pair(&block) + super do |key, value| + convert_hashes_to_parameters(key, value) + end + + super + end + + alias_method :each, :each_pair + # Attribute that keeps track of converted arrays, if any, to avoid double # looping in the common use case permit + mass-assignment. Defined in a # method to instantiate it only if needed. @@ -176,7 +207,6 @@ module ActionController # Person.new(params) # => #<Person id: nil, name: "Francesco"> def permit! each_pair do |key, value| - value = convert_hashes_to_parameters(key, value) Array.wrap(value).each do |v| v.permit! if v.respond_to? :permit! end @@ -331,11 +361,56 @@ module ActionController # params.slice(:a, :b) # => {"a"=>1, "b"=>2} # params.slice(:d) # => {} def slice(*keys) - self.class.new(super).tap do |new_instance| - new_instance.permitted = @permitted + new_instance_with_inherited_permitted_status(super) + end + + # Removes and returns the key/value pairs matching the given keys. + # + # params = ActionController::Parameters.new(a: 1, b: 2, c: 3) + # params.extract!(:a, :b) # => {"a"=>1, "b"=>2} + # params # => {"c"=>3} + def extract!(*keys) + new_instance_with_inherited_permitted_status(super) + end + + # Returns a new <tt>ActionController::Parameters</tt> with the results of + # running +block+ once for every value. The keys are unchanged. + # + # params = ActionController::Parameters.new(a: 1, b: 2, c: 3) + # params.transform_values { |x| x * 2 } + # # => {"a"=>2, "b"=>4, "c"=>6} + def transform_values + if block_given? + new_instance_with_inherited_permitted_status(super) + else + super + end + end + + # This method is here only to make sure that the returned object has the + # correct +permitted+ status. It should not matter since the parent of + # this object is +HashWithIndifferentAccess+ + def transform_keys # :nodoc: + if block_given? + new_instance_with_inherited_permitted_status(super) + else + super end end + # Deletes and returns a key-value pair from +Parameters+ whose key is equal + # to key. If the key is not found, returns the default value. If the + # optional code block is given and the key is not found, pass in the key + # and return the result of block. + def delete(key, &block) + convert_hashes_to_parameters(key, super, false) + end + + # Equivalent to Hash#keep_if, but returns nil if no changes were made. + def select!(&block) + convert_value_to_parameters(super) + end + # Returns an exact copy of the <tt>ActionController::Parameters</tt> # instance. +permitted+ state is kept on the duped object. # @@ -356,6 +431,12 @@ module ActionController end private + def new_instance_with_inherited_permitted_status(hash) + self.class.new(hash).tap do |new_instance| + new_instance.permitted = @permitted + end + end + def convert_hashes_to_parameters(key, value, assign_if_converted=true) converted = convert_value_to_parameters(value) self[key] = converted if assign_if_converted && !converted.equal?(value) |