Added checks for 2FA to the API `/sessions` endpoint and the Resource Owner...

Added checks for 2FA to the API `/sessions` endpoint and the Resource Owner Password Credentials flow.

app/services/user_retrieval_service.rb

+class UserRetrievalService
+  attr_accessor :login, :password
+
+  def initialize(login, password)
+    @login = login
+    @password = password
+  end
+
+  def execute
+    user = Gitlab::Auth.find_with_user_password(login, password)
+    user unless user.two_factor_enabled?
+  end
+end
\ No newline at end of file

config/initializers/doorkeeper.rb

@@ -12,7 +12,7 @@ Doorkeeper.configure do
   end
 
   resource_owner_from_credentials do |routes|
-    Gitlab::Auth.find_with_user_password(params[:username], params[:password])
+    UserRetrievalService.new(params[:username], params[:password]).execute
   end
 
   # If you want to restrict access to the web interface for adding oauth authorized applications, you need to declare the block below.

lib/api/helpers.rb

@@ -275,6 +275,10 @@ module API
       end
     end
 
+    def render_2fa_error!
+      render_api_error!('401 You have 2FA enabled. Please use a personal access token to access the API', 401)
+    end
+
     def render_api_error!(message, status)
       error!({ 'message' => message }, status)
     end

lib/api/session.rb

@@ -14,6 +14,7 @@ module API
       user = Gitlab::Auth.find_with_user_password(params[:email] || params[:login], params[:password])
 
       return unauthorized! unless user
+      return render_2fa_error! if user.two_factor_enabled?
       present user, with: Entities::UserLogin
     end
   end

spec/requests/api/oauth_tokens_spec.rb

+require 'spec_helper'
+
+describe API::API, api: true  do
+  include ApiHelpers
+
+  context 'Resource Owner Password Credentials' do
+    def request_oauth_token(user)
+      post '/oauth/token', username: user.username, password: user.password, grant_type: 'password'
+    end
+
+    context 'when user has 2FA enabled' do
+      it 'does not create an access token' do
+        user = create(:user, :two_factor)
+        request_oauth_token(user)
+
+        expect(response).to have_http_status(401)
+        expect(json_response['error']).to eq('invalid_grant')
+      end
+    end
+
+    context 'when user does not have 2FA enabled' do
+      it 'creates an access token' do
+        user = create(:user)
+        request_oauth_token(user)
+
+        expect(response).to have_http_status(200)
+        expect(json_response['access_token']).not_to be_nil
+      end
+    end
+  end
+end
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spec/requests/api/session_spec.rb

@@ -17,6 +17,16 @@ describe API::API, api: true  do
         expect(json_response['can_create_project']).to eq(user.can_create_project?)
         expect(json_response['can_create_group']).to eq(user.can_create_group?)
       end
+
+      context 'with 2FA enabled' do
+        it 'rejects sign in attempts' do
+          user = create(:user, :two_factor)
+
+          post api('/session'), email: user.email, password: user.password
+
+          expect(response).to have_http_status(401)
+        end
+      end
     end
 
     context 'when email has case-typo and password is valid' do

spec/services/user_retrieval_service_spec.rb

+require 'spec_helper'
+
+describe UserRetrievalService, services: true do
+  context 'user retrieval' do
+    it 'retrieves the correct user' do
+      user = create(:user)
+      retrieved_user = described_class.new(user.username, user.password).execute
+
+      expect(retrieved_user).to eq(user)
+    end
+
+    it 'returns nil when 2FA is enabled' do
+      user = create(:user, :two_factor)
+      retrieved_user = described_class.new(user.username, user.password).execute
+
+      expect(retrieved_user).to be_nil
+    end
+  end
+end
\ No newline at end of file