Move all API authentication code to APIGuard

app/models/oauth_access_token.rb

 class OauthAccessToken < Doorkeeper::AccessToken
   belongs_to :resource_owner, class_name: 'User'
   belongs_to :application, class_name: 'Doorkeeper::Application'
+
+  alias_method :user, :resource_owner
 end

lib/api/api_guard.rb

@@ -42,6 +42,38 @@ module API
 
     # Helper Methods for Grape Endpoint
     module HelperMethods
+      def find_current_user
+        user =
+          find_user_from_private_token ||
+          find_user_from_oauth_token ||
+          find_user_from_warden
+
+        return nil unless user
+
+        raise UnauthorizedError unless Gitlab::UserAccess.new(user).allowed? && user.can?(:access_api)
+
+        user
+      end
+
+      def private_token
+        params[PRIVATE_TOKEN_PARAM] || env[PRIVATE_TOKEN_HEADER]
+      end
+
+      private
+
+      def find_user_from_private_token
+        token_string = private_token.to_s
+        return nil unless token_string.present?
+
+        user =
+          find_user_by_authentication_token(token_string) ||
+          find_user_by_personal_access_token(token_string)
+
+        raise UnauthorizedError unless user
+
+        user
+      end
+
       # Invokes the doorkeeper guard.
       #
       # If token is presented and valid, then it sets @current_user.
@@ -60,70 +92,89 @@ module API
       #   scopes: (optional) scopes required for this guard.
       #           Defaults to empty array.
       #
-      def doorkeeper_guard(scopes: [])
-        access_token = find_access_token
-        return nil unless access_token
-
-        case AccessTokenValidationService.new(access_token, request: request).validate(scopes: scopes)
-        when AccessTokenValidationService::INSUFFICIENT_SCOPE
-          raise InsufficientScopeError.new(scopes)
-
-        when AccessTokenValidationService::EXPIRED
-          raise ExpiredError
-
-        when AccessTokenValidationService::REVOKED
-          raise RevokedError
+      def find_user_from_oauth_token
+        access_token = find_oauth_access_token
+        return unless access_token
 
-        when AccessTokenValidationService::VALID
-          User.find(access_token.resource_owner_id)
+        find_user_by_access_token(access_token)
       end
+
+      def find_user_by_authentication_token(token_string)
+        User.find_by_authentication_token(token_string)
       end
 
-      def find_user_by_private_token(scopes: [])
-        token_string = (params[PRIVATE_TOKEN_PARAM] || env[PRIVATE_TOKEN_HEADER]).to_s
+      def find_user_by_personal_access_token(token_string)
+        access_token = PersonalAccessToken.find_by_token(token_string)
+        return unless access_token
 
-        return nil unless token_string.present?
+        find_user_by_access_token(access_token)
+      end
 
-        user =
-          find_user_by_authentication_token(token_string) ||
-          find_user_by_personal_access_token(token_string, scopes)
+      # Check the Rails session for valid authentication details
+      def find_user_from_warden
+        warden.try(:authenticate) if verified_request?
+      end
 
-        raise UnauthorizedError unless user
+      def warden
+        env['warden']
+      end
 
-        user
+      # Check if the request is GET/HEAD, or if CSRF token is valid.
+      def verified_request?
+        Gitlab::RequestForgeryProtection.verified?(env)
       end
 
-      private
+      def find_oauth_access_token
+        return @oauth_access_token if defined?(@oauth_access_token)
 
-      def find_user_by_authentication_token(token_string)
-        User.find_by_authentication_token(token_string)
-      end
+        token = Doorkeeper::OAuth::Token.from_request(doorkeeper_request, *Doorkeeper.configuration.access_token_methods)
+        return @oauth_access_token = nil unless token
 
-      def find_user_by_personal_access_token(token_string, scopes)
-        access_token = PersonalAccessToken.active.find_by_token(token_string)
-        return unless access_token
+        @oauth_access_token = OauthAccessToken.by_token(token)
+        raise UnauthorizedError unless @oauth_access_token
 
-        if AccessTokenValidationService.new(access_token, request: request).include_any_scope?(scopes)
-          User.find(access_token.user_id)
-        end
+        @oauth_access_token.revoke_previous_refresh_token!
+        @oauth_access_token
       end
 
-      def find_access_token
-        return @access_token if defined?(@access_token)
+      def find_user_by_access_token(access_token)
+        scopes = scopes_registered_for_endpoint
 
-        token = Doorkeeper::OAuth::Token.from_request(doorkeeper_request, *Doorkeeper.configuration.access_token_methods)
-        return @access_token = nil unless token
+        case AccessTokenValidationService.new(access_token, request: request).validate(scopes: scopes)
+        when AccessTokenValidationService::INSUFFICIENT_SCOPE
+          raise InsufficientScopeError.new(scopes)
 
-        @access_token = Doorkeeper::AccessToken.by_token(token)
-        raise UnauthorizedError unless @access_token
+        when AccessTokenValidationService::EXPIRED
+          raise ExpiredError
 
-        @access_token.revoke_previous_refresh_token!
-        @access_token
+        when AccessTokenValidationService::REVOKED
+          raise RevokedError
+
+        when AccessTokenValidationService::VALID
+          access_token.user
+        end
       end
 
       def doorkeeper_request
         @doorkeeper_request ||= ActionDispatch::Request.new(env)
       end
+
+      # An array of scopes that were registered (using `allow_access_with_scope`)
+      # for the current endpoint class. It also returns scopes registered on
+      # `API::API`, since these are meant to apply to all API routes.
+      def scopes_registered_for_endpoint
+        @scopes_registered_for_endpoint ||=
+          begin
+            endpoint_classes = [options[:for].presence, ::API::API].compact
+            endpoint_classes.reduce([]) do |memo, endpoint|
+              if endpoint.respond_to?(:allowed_scopes)
+                memo.concat(endpoint.allowed_scopes)
+              else
+                memo
+              end
+            end
+          end
+      end
     end
 
     module ClassMethods

lib/api/helpers.rb

@@ -3,8 +3,6 @@ module API
     include Gitlab::Utils
     include Helpers::Pagination
 
-    UnauthorizedError = Class.new(StandardError)
-
     SUDO_HEADER = "HTTP_SUDO".freeze
     SUDO_PARAM = :sudo
 
@@ -379,47 +377,16 @@ module API
 
     private
 
-    def private_token
-      params[APIGuard::PRIVATE_TOKEN_PARAM] || env[APIGuard::PRIVATE_TOKEN_HEADER]
-    end
-
-    def warden
-      env['warden']
-    end
-
-    # Check if the request is GET/HEAD, or if CSRF token is valid.
-    def verified_request?
-      Gitlab::RequestForgeryProtection.verified?(env)
-    end
-
-    # Check the Rails session for valid authentication details
-    def find_user_from_warden
-      warden.try(:authenticate) if verified_request?
-    end
-
     def initial_current_user
       return @initial_current_user if defined?(@initial_current_user)
 
       begin
         @initial_current_user = Gitlab::Auth::UniqueIpsLimiter.limit_user! { find_current_user }
-      rescue APIGuard::UnauthorizedError, UnauthorizedError
+      rescue APIGuard::UnauthorizedError
         unauthorized!
       end
     end
 
-    def find_current_user
-      user =
-        find_user_by_private_token(scopes: scopes_registered_for_endpoint) ||
-        doorkeeper_guard(scopes: scopes_registered_for_endpoint) ||
-        find_user_from_warden
-
-      return nil unless user
-
-      raise UnauthorizedError unless Gitlab::UserAccess.new(user).allowed? && user.can?(:access_api)
-
-      user
-    end
-
     def sudo!
       return unless sudo_identifier
       return unless initial_current_user
@@ -479,22 +446,5 @@ module API
 
       exception.status == 500
     end
-
-    # An array of scopes that were registered (using `allow_access_with_scope`)
-    # for the current endpoint class. It also returns scopes registered on
-    # `API::API`, since these are meant to apply to all API routes.
-    def scopes_registered_for_endpoint
-      @scopes_registered_for_endpoint ||=
-        begin
-          endpoint_classes = [options[:for].presence, ::API::API].compact
-          endpoint_classes.reduce([]) do |memo, endpoint|
-            if endpoint.respond_to?(:allowed_scopes)
-              memo.concat(endpoint.allowed_scopes)
-            else
-              memo
-            end
-          end
-        end
-    end
   end
 end

spec/requests/api/helpers_spec.rb

@@ -222,13 +222,6 @@ describe API::Helpers do
         expect { current_user }.to raise_error /401/
       end
 
-      it "returns a 401 response for a token without the appropriate scope" do
-        personal_access_token = create(:personal_access_token, user: user, scopes: ['read_user'])
-        env[API::APIGuard::PRIVATE_TOKEN_HEADER] = personal_access_token.token
-
-        expect { current_user }.to raise_error /401/
-      end
-
       it "leaves user as is when sudo not specified" do
         env[API::APIGuard::PRIVATE_TOKEN_HEADER] = personal_access_token.token
         expect(current_user).to eq(user)
@@ -238,18 +231,25 @@ describe API::Helpers do
         expect(current_user).to eq(user)
       end
 
+      it "does not allow tokens without the appropriate scope" do
+        personal_access_token = create(:personal_access_token, user: user, scopes: ['read_user'])
+        env[API::APIGuard::PRIVATE_TOKEN_HEADER] = personal_access_token.token
+
+        expect { current_user }.to raise_error API::APIGuard::InsufficientScopeError
+      end
+
       it 'does not allow revoked tokens' do
         personal_access_token.revoke!
         env[API::APIGuard::PRIVATE_TOKEN_HEADER] = personal_access_token.token
 
-        expect { current_user }.to raise_error /401/
+        expect { current_user }.to raise_error API::APIGuard::RevokedError
       end
 
       it 'does not allow expired tokens' do
         personal_access_token.update_attributes!(expires_at: 1.day.ago)
         env[API::APIGuard::PRIVATE_TOKEN_HEADER] = personal_access_token.token
 
-        expect { current_user }.to raise_error /401/
+        expect { current_user }.to raise_error API::APIGuard::ExpiredError
       end
     end
 

spec/support/api/scopes/read_user_shared_examples.rb

@@ -27,10 +27,10 @@ shared_examples_for 'allows the "read_user" scope' do
         stub_container_registry_config(enabled: true)
       end
 
-      it 'returns a "401" response' do
+      it 'returns a "403" response' do
         get api_call.call(path, user, personal_access_token: token)
 
-        expect(response).to have_http_status(401)
+        expect(response).to have_http_status(403)
       end
     end
   end
@@ -74,10 +74,10 @@ shared_examples_for 'does not allow the "read_user" scope' do
   context 'when the requesting token has the "read_user" scope' do
     let(:token) { create(:personal_access_token, scopes: ['read_user'], user: user) }
 
-    it 'returns a "401" response' do
+    it 'returns a "403" response' do
       post api_call.call(path, user, personal_access_token: token), attributes_for(:user, projects_limit: 3)
 
-      expect(response).to have_http_status(401)
+      expect(response).to have_http_status(403)
     end
   end
 end