Allow whitelisting for "external collaborator by default" setting

EE port of https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/17711.

Gemfile

@@ -205,6 +205,9 @@ gem 're2', '~> 1.1.1'
 
 gem 'version_sorter', '~> 2.1.0'
 
+# Export Ruby Regex to Javascript
+gem 'js_regex', '~> 2.2.1'
+
 # User agent parsing
 gem 'device_detector'
 

Gemfile.lock

@@ -456,6 +456,8 @@ GEM
       oauth (~> 0.5, >= 0.5.0)
     jmespath (1.3.1)
     jquery-atwho-rails (1.3.2)
+    js_regex (2.2.1)
+      regexp_parser (>= 0.4.11, <= 0.5.0)
     json (1.8.6)
     json-jwt (1.9.4)
       activesupport
@@ -755,6 +757,7 @@ GEM
       redis-store (>= 1.2, < 2)
     redis-store (1.4.1)
       redis (>= 2.2, < 5)
+    regexp_parser (0.5.0)
     representable (3.0.4)
       declarative (< 0.1.0)
       declarative-option (< 0.2.0)
@@ -1110,6 +1113,7 @@ DEPENDENCIES
   influxdb (~> 0.2)
   jira-ruby (~> 1.4)
   jquery-atwho-rails (~> 1.3.2)
+  js_regex (~> 2.2.1)
   json-schema (~> 2.8.0)
   jwt (~> 1.5.6)
   kaminari (~> 1.0)

Gemfile.rails5.lock

@@ -459,6 +459,8 @@ GEM
       oauth (~> 0.5, >= 0.5.0)
     jmespath (1.3.1)
     jquery-atwho-rails (1.3.2)
+    js_regex (2.2.1)
+      regexp_parser (>= 0.4.11, <= 0.5.0)
     json (1.8.6)
     json-jwt (1.9.4)
       activesupport
@@ -764,6 +766,7 @@ GEM
       redis-store (>= 1.2, < 2)
     redis-store (1.4.1)
       redis (>= 2.2, < 5)
+    regexp_parser (0.5.0)
     representable (3.0.4)
       declarative (< 0.1.0)
       declarative-option (< 0.2.0)
@@ -1120,6 +1123,7 @@ DEPENDENCIES
   influxdb (~> 0.2)
   jira-ruby (~> 1.4)
   jquery-atwho-rails (~> 1.3.2)
+  js_regex (~> 2.2.1)
   json-schema (~> 2.8.0)
   jwt (~> 1.5.6)
   kaminari (~> 1.0)

app/assets/javascripts/pages/admin/application_settings/account_and_limits.js

+import { __ } from '~/locale';
+
+export const PLACEHOLDER_USER_EXTERNAL_DEFAULT_TRUE = __('Regex pattern');
+export const PLACEHOLDER_USER_EXTERNAL_DEFAULT_FALSE = __('To define internal users, first enable new users set to external');
+
+function setUserInternalRegexPlaceholder(checkbox) {
+  const userInternalRegex = document.getElementById('application_setting_user_default_internal_regex');
+  if (checkbox && userInternalRegex) {
+    if (checkbox.checked) {
+      userInternalRegex.readOnly = false;
+      userInternalRegex.placeholder = PLACEHOLDER_USER_EXTERNAL_DEFAULT_TRUE;
+    } else {
+      userInternalRegex.readOnly = true;
+      userInternalRegex.placeholder = PLACEHOLDER_USER_EXTERNAL_DEFAULT_FALSE;
+    }
+  }
+}
+
+export default function initUserInternalRegexPlaceholder() {
+  const checkbox = document.getElementById('application_setting_user_default_external');
+  setUserInternalRegexPlaceholder(checkbox);
+  checkbox.addEventListener('change', () => {
+    setUserInternalRegexPlaceholder(checkbox);
+  });
+}

app/assets/javascripts/pages/admin/index.js

 import initAdmin from './admin';
+import initUserInternalRegexPlaceholder from './application_settings/account_and_limits';
 
-document.addEventListener('DOMContentLoaded', initAdmin);
+document.addEventListener('DOMContentLoaded', () => {
+  initAdmin();
+  initUserInternalRegexPlaceholder();
+});

app/assets/javascripts/pages/admin/users/new/index.js

+import $ from 'jquery';
+
+export default class UserInternalRegexHandler {
+  constructor() {
+    this.regexPattern = $('[data-user-internal-regex-pattern]').data('user-internal-regex-pattern');
+    if (this.regexPattern && this.regexPattern !== '') {
+      this.regexOptions = $('[data-user-internal-regex-options]').data('user-internal-regex-options');
+      this.external = $('#user_external');
+      this.warningMessage = $('#warning_external_automatically_set');
+      this.addListenerToEmailField();
+      this.addListenerToUserExternalCheckbox();
+    }
+  }
+
+  addListenerToEmailField() {
+    $('#user_email').on('input', (event) => {
+      this.setExternalCheckbox(event.currentTarget.value);
+    });
+  }
+
+  addListenerToUserExternalCheckbox() {
+    this.external.on('click', () => {
+      this.warningMessage.addClass('hidden');
+    });
+  }
+
+  isEmailInternal(email) {
+    const regex = new RegExp(this.regexPattern, this.regexOptions);
+    return regex.test(email);
+  }
+
+  setExternalCheckbox(email) {
+    const isChecked = this.external.prop('checked');
+    if (this.isEmailInternal(email)) {
+      if (isChecked) {
+        this.external.prop('checked', false);
+        this.warningMessage.removeClass('hidden');
+      }
+    } else if (!isChecked) {
+      this.external.prop('checked', true);
+      this.warningMessage.addClass('hidden');
+    }
+  }
+}
+
+document.addEventListener('DOMContentLoaded', () => {
+  // eslint-disable-next-line
+  new UserInternalRegexHandler();
+});

app/helpers/application_settings_helper.rb

@@ -256,6 +256,7 @@ module ApplicationSettingsHelper
       :instance_statistics_visibility_private,
       :user_default_external,
       :user_show_add_ssh_key_message,
+      :user_default_internal_regex,
       :user_oauth_applications,
       :version_check_enabled,
       :web_ide_clientside_preview_enabled

app/helpers/users_helper.rb

@@ -23,6 +23,17 @@ module UsersHelper
     profile_tabs.include?(tab)
   end
 
+  def user_internal_regex_data
+    settings = Gitlab::CurrentSettings.current_application_settings
+
+    pattern, options = if settings.user_default_internal_regex_enabled?
+                         regex = settings.user_default_internal_regex_instance
+                         JsRegex.new(regex).to_h.slice(:source, :options).values
+                       end
+
+    { user_internal_regex_pattern: pattern, user_internal_regex_options: options }
+  end
+
   def current_user_menu_items
     @current_user_menu_items ||= get_current_user_menu_items
   end

app/models/application_setting.rb

@@ -193,6 +193,8 @@ class ApplicationSetting < ActiveRecord::Base
             numericality: { less_than_or_equal_to: :gitaly_timeout_default },
             if: :gitaly_timeout_default
 
+  validates :user_default_internal_regex, js_regex: true, allow_nil: true
+
   SUPPORTED_KEY_TYPES.each do |type|
     validates :"#{type}_key_restriction", presence: true, key_restriction: { type: type }
   end
@@ -300,6 +302,7 @@ class ApplicationSetting < ActiveRecord::Base
       usage_ping_enabled: Settings.gitlab['usage_ping_enabled'],
       instance_statistics_visibility_private: false,
       user_default_external: false,
+      user_default_internal_regex: nil,
       user_show_add_ssh_key_message: true
     }
   end
@@ -436,6 +439,14 @@ class ApplicationSetting < ActiveRecord::Base
     password_authentication_enabled_for_web? || password_authentication_enabled_for_git?
   end
 
+  def user_default_internal_regex_enabled?
+    user_default_external? && user_default_internal_regex.present?
+  end
+
+  def user_default_internal_regex_instance
+    Regexp.new(user_default_internal_regex, Regexp::IGNORECASE)
+  end
+
   delegate :terms, to: :latest_terms, allow_nil: true
   def latest_terms
     @latest_terms ||= Term.latest

app/services/users/build_service.rb

@@ -4,6 +4,10 @@ module Users
   class BuildService < BaseService
     prepend ::EE::Users::BuildService
 
+    delegate :user_default_internal_regex_enabled?,
+             :user_default_internal_regex_instance,
+             to: :'Gitlab::CurrentSettings.current_application_settings'
+
     def initialize(current_user, params = {})
       @current_user = current_user
       @params = params.dup
@@ -91,6 +95,10 @@ module Users
         if params[:reset_password]
           user_params.merge!(force_random_password: true, password_expires_at: nil)
         end
+
+        if user_default_internal_regex_enabled? && !user_params.key?(:external)
+          user_params[:external] = user_external?
+        end
       else
         allowed_signup_params = signup_params
         allowed_signup_params << :skip_confirmation if skip_authorization
@@ -107,5 +115,9 @@ module Users
     def skip_user_confirmation_email_from_setting
       !Gitlab::CurrentSettings.send_user_confirmation_email
     end
+
+    def user_external?
+      user_default_internal_regex_instance.match(params[:email]).nil?
+    end
   end
 end

app/validators/js_regex_validator.rb

+class JsRegexValidator < ActiveModel::EachValidator
+  def validate_each(record, attribute, value)
+    return true if value.blank?
+
+    parsed_regex = JsRegex.new(Regexp.new(value, Regexp::IGNORECASE))
+
+    if parsed_regex.source.empty?
+      record.errors.add(attribute, "Regex Pattern #{value} can not be expressed in Javascript")
+    else
+      parsed_regex.warnings.each { |warning| record.errors.add(attribute, warning) }
+    end
+  rescue RegexpError => regex_error
+    record.errors.add(attribute, regex_error.to_s)
+  end
+end

app/views/admin/application_settings/_account_and_limit.html.haml

@@ -32,6 +32,13 @@
         = f.check_box :user_default_external, class: 'form-check-input'
         = f.label :user_default_external, class: 'form-check-label' do
           Newly registered users will by default be external
+      .prepend-top-10
+        = _('Internal users')
+      = f.text_field :user_default_internal_regex, placeholder: _('Regex pattern'), class: 'form-control prepend-top-5'
+      .help-block
+        = _('Specify an e-mail address regex pattern to identify default internal users.')
+        = link_to _('More information'), help_page_path('user/permissions', anchor: 'external-users-permissions'),
+          target: '_blank'
     .form-group
       = f.label :user_show_add_ssh_key_message, 'Prompt users to upload SSH keys', class: 'label-bold'
       .form-check

app/views/admin/users/_access_levels.html.haml

@@ -41,8 +41,12 @@
   .form-group.row
     .col-sm-2.text-right
       = f.label :external, class: 'col-form-label'
+    .hidden{ data: user_internal_regex_data }
     .col-sm-10
       = f.check_box :external do
         External
       %p.light
         External users cannot see internal or private projects unless access is explicitly granted. Also, external users cannot create projects or groups.
+      %row.hidden#warning_external_automatically_set.hidden
+        .badge.badge-warning.text-white
+          = _('Automatically marked as default internal user')

changelogs/unreleased/feature-whitelist-new-users-as-internal.yml

+---
+title: Add an option to whitelist users based on email address as internal when the "New user set to external" setting is enabled.
+merge_request: 17711
+author: Roger Rüttimann
+type: added

db/migrate/20180308125206_add_user_internal_regex_to_application_setting.rb

+class AddUserInternalRegexToApplicationSetting < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  def up
+    add_column :application_settings, :user_default_internal_regex, :string, null: true
+  end
+
+  def down
+    remove_column :application_settings, :user_default_internal_regex
+  end
+end

db/schema.rb

@@ -197,6 +197,7 @@ ActiveRecord::Schema.define(version: 20180823132905) do
     t.string "external_authorization_service_url"
     t.string "external_authorization_service_default_label"
     t.boolean "pages_domain_verification_enabled", default: true, null: false
+    t.string "user_default_internal_regex"
     t.boolean "allow_local_requests_from_hooks_and_services", default: false, null: false
     t.float "external_authorization_service_timeout", default: 0.5
     t.text "external_auth_client_cert"

doc/user/permissions.md

@@ -205,6 +205,21 @@ will find the option to flag the user as external.
 By default new users are not set as external users. This behavior can be changed
 by an administrator under **Admin > Application Settings**.
 
+### Default internal users
+
+The "Internal users" field allows specifying an e-mail address regex pattern to identify default internal users.  
+
+New users whose email address matches the regex pattern will be set to internal by default rather than an external collaborator.
+
+The regex pattern format is Ruby, but it needs to be convertible to JavaScript, and the ignore case flag will be set, e.g. "/regex pattern/i".
+
+Here are some examples:
+
+- Use `\.internal@domain\.com` to mark email addresses containing ".internal@domain.com" internal.
+- Use `^(?:(?!\.ext@domain\.com).)*$\r?` to mark users with email addresses NOT including .ext@domain.com internal.
+
+Please be aware that this regex could lead to a DOS attack, [see](https://en.wikipedia.org/wiki/ReDoS?) ReDos on Wikipedia.
+
 ## Auditor users **[PREMIUM ONLY]**
 
 >[Introduced][ee-998] in [GitLab Premium][eep] 8.17.

locale/gitlab.pot

@@ -876,6 +876,9 @@ msgstr ""
 msgid "AutoDevOps|enable Auto DevOps"
 msgstr ""
 
+msgid "Automatically marked as default internal user"
+msgstr ""
+
 msgid "Available"
 msgstr ""
 
@@ -4055,6 +4058,9 @@ msgstr ""
 msgid "Internal - The project can be accessed by any logged in user."
 msgstr ""
 
+msgid "Internal users"
+msgstr ""
+
 msgid "Interval Pattern"
 msgstr ""
 
@@ -5973,6 +5979,9 @@ msgstr[1] ""
 msgid "Regenerate key"
 msgstr ""
 
+msgid "Regex pattern"
+msgstr ""
+
 msgid "Register / Sign In"
 msgstr ""
 
@@ -6732,6 +6741,9 @@ msgstr ""
 msgid "Specific Runners"
 msgstr ""
 
+msgid "Specify an e-mail address regex pattern to identify default internal users."
+msgstr ""
+
 msgid "Specify the following URL during the Runner setup:"
 msgstr ""
 
@@ -7449,6 +7461,9 @@ msgstr ""
 msgid "To connect an SVN repository, check out %{svn_link}."
 msgstr ""
 
+msgid "To define internal users, first enable new users set to external"
+msgstr ""
+
 msgid "To get started you enter your FogBugz URL and login information below. In the next steps, you'll be able to map users and select the projects you want to import."
 msgstr ""
 

spec/features/admin/admin_settings_spec.rb

@@ -103,6 +103,18 @@ describe 'Admin updates settings' do
     expect(page).to have_content "Application settings saved successfully"
   end
 
+  it 'Change New users set to external', :js do
+    user_internal_regex = find('#application_setting_user_default_internal_regex', visible: :all)
+
+    expect(user_internal_regex).to be_readonly
+    expect(user_internal_regex['placeholder']).to eq 'To define internal users, first enable new users set to external'
+
+    check 'application_setting_user_default_external'
+
+    expect(user_internal_regex).not_to be_readonly
+    expect(user_internal_regex['placeholder']).to eq 'Regex pattern'
+  end
+
   it 'Change Sign-in restrictions' do
     page.within('.as-signin') do
       fill_in 'Home page URL', with: 'https://about.gitlab.com/'

spec/features/admin/admin_users_spec.rb

@@ -125,6 +125,52 @@ describe "Admin::Users" do
         expect(page).to have_content('Username can contain only letters, digits')
       end
     end
+
+    context 'with new users set to external enabled' do
+      context 'with regex to match internal user email address set', :js do
+        before do
+          stub_application_setting(user_default_external: true)
+          stub_application_setting(user_default_internal_regex: '.internal@')
+
+          visit new_admin_user_path
+        end
+
+        def expects_external_to_be_checked
+          expect(find('#user_external')).to be_checked
+        end
+
+        def expects_external_to_be_unchecked
+          expect(find('#user_external')).not_to be_checked
+        end
+
+        def expects_warning_to_be_hidden
+          expect(find('#warning_external_automatically_set', visible: :all)[:class]).to include 'hidden'
+        end
+
+        def expects_warning_to_be_shown
+          expect(find('#warning_external_automatically_set')[:class]).not_to include 'hidden'
+        end
+
+        it 'automatically unchecks external for matching email' do
+          expects_external_to_be_checked
+          expects_warning_to_be_hidden
+
+          fill_in 'user_email', with: 'test.internal@domain.ch'
+
+          expects_external_to_be_unchecked
+          expects_warning_to_be_shown
+
+          fill_in 'user_email', with: 'test@domain.ch'
+
+          expects_external_to_be_checked
+          expects_warning_to_be_hidden
+
+          uncheck 'user_external'
+
+          expects_warning_to_be_hidden
+        end
+      end
+    end
   end
 
   describe "GET /admin/users/:id" do

spec/helpers/users_helper_spec.rb

@@ -42,6 +42,30 @@ describe UsersHelper do
     end
   end
 
+  describe '#user_internal_regex_data' do
+    using RSpec::Parameterized::TableSyntax
+
+    where(:user_default_external, :user_default_internal_regex, :result) do
+      false | nil                | { user_internal_regex_pattern: nil, user_internal_regex_options: nil }
+      false | ''                 | { user_internal_regex_pattern: nil, user_internal_regex_options: nil }
+      false | 'mockRegexPattern' | { user_internal_regex_pattern: nil, user_internal_regex_options: nil }
+      true  | nil                | { user_internal_regex_pattern: nil, user_internal_regex_options: nil }
+      true  | ''                 | { user_internal_regex_pattern: nil, user_internal_regex_options: nil }
+      true  | 'mockRegexPattern' | { user_internal_regex_pattern: 'mockRegexPattern', user_internal_regex_options: 'gi' }
+    end
+
+    with_them do
+      before do
+        stub_application_setting(user_default_external: user_default_external)
+        stub_application_setting(user_default_internal_regex: user_default_internal_regex)
+      end
+
+      subject { helper.user_internal_regex_data }
+
+      it { is_expected.to eq(result) }
+    end
+  end
+
   describe '#current_user_menu_items' do
     subject(:items) { helper.current_user_menu_items }
 

spec/javascripts/fixtures/admin_users.rb

+require 'spec_helper'
+
+describe Admin::UsersController, '(JavaScript fixtures)', type: :controller do
+  include StubENV
+  include JavaScriptFixturesHelpers
+
+  let(:admin) { create(:admin) }
+
+  before do
+    stub_env('IN_MEMORY_APPLICATION_SETTINGS', 'false')
+    sign_in(admin)
+  end
+
+  render_views
+
+  before(:all) do
+    clean_frontend_fixtures('admin/users')
+  end
+
+  it 'admin/users/new_with_internal_user_regex.html.raw' do |example|
+    stub_application_setting(user_default_external: true)
+    stub_application_setting(user_default_internal_regex: '^(?:(?!\.ext@).)*$\r?')
+
+    get :new
+
+    expect(response).to be_success
+    store_frontend_fixture(response, example.description)
+  end
+end

spec/javascripts/fixtures/application_settings.rb

+require 'spec_helper'
+
+describe Admin::ApplicationSettingsController, '(JavaScript fixtures)', type: :controller do
+  include StubENV
+  include JavaScriptFixturesHelpers
+
+  let(:admin) { create(:admin) }
+  let(:namespace) { create(:namespace, name: 'frontend-fixtures' )}
+  let(:project) { create(:project_empty_repo, namespace: namespace, path: 'application-settings') }
+
+  before do
+    stub_env('IN_MEMORY_APPLICATION_SETTINGS', 'false')
+    sign_in(admin)
+  end
+
+  render_views
+
+  before(:all) do
+    clean_frontend_fixtures('application_settings/')
+  end
+
+  after do
+    remove_repository(project)
+  end
+
+  it 'application_settings/accounts_and_limit.html.raw' do |example|
+    stub_application_setting(user_default_external: false)
+
+    get :show
+
+    expect(response).to be_success
+    store_frontend_fixture(response, example.description)
+  end
+end

spec/javascripts/pages/admin/application_settings/account_and_limits_spec.js

+import $ from 'jquery';
+import initUserInternalRegexPlaceholder, { PLACEHOLDER_USER_EXTERNAL_DEFAULT_FALSE,
+  PLACEHOLDER_USER_EXTERNAL_DEFAULT_TRUE } from '~/pages/admin/application_settings/account_and_limits';
+
+describe('AccountAndLimits', () => {
+  const FIXTURE = 'application_settings/accounts_and_limit.html.raw';
+  let $userDefaultExternal;
+  let $userInternalRegex;
+  preloadFixtures(FIXTURE);
+
+  beforeEach(() => {
+    loadFixtures(FIXTURE);
+    initUserInternalRegexPlaceholder();
+    $userDefaultExternal = $('#application_setting_user_default_external');
+    $userInternalRegex = document.querySelector('#application_setting_user_default_internal_regex');
+  });
+
+  describe('Changing of userInternalRegex when userDefaultExternal', () => {
+    it('is unchecked', () => {
+      expect($userDefaultExternal.prop('checked')).toBeFalsy();
+      expect($userInternalRegex.placeholder).toEqual(PLACEHOLDER_USER_EXTERNAL_DEFAULT_FALSE);
+      expect($userInternalRegex.readOnly).toBeTruthy();
+    });
+
+    it('is checked', (done) => {
+      if (!$userDefaultExternal.prop('checked')) $userDefaultExternal.click();
+      expect($userDefaultExternal.prop('checked')).toBeTruthy();
+      expect($userInternalRegex.placeholder).toEqual(PLACEHOLDER_USER_EXTERNAL_DEFAULT_TRUE);
+      expect($userInternalRegex.readOnly).toBeFalsy();
+      done();
+    });
+  });
+});

spec/javascripts/pages/admin/users/new/index_spec.js

+import $ from 'jquery';
+import UserInternalRegexHandler from '~/pages/admin/users/new/index';
+
+describe('UserInternalRegexHandler', () => {
+  const FIXTURE = 'admin/users/new_with_internal_user_regex.html.raw';
+  let $userExternal;
+  let $userEmail;
+  let $warningMessage;
+
+  preloadFixtures(FIXTURE);
+
+  beforeEach(() => {
+    loadFixtures(FIXTURE);
+    // eslint-disable-next-line no-new
+    new UserInternalRegexHandler();
+    $userExternal = $('#user_external');
+    $userEmail = $('#user_email');
+    $warningMessage = $('#warning_external_automatically_set');
+    if (!$userExternal.prop('checked')) $userExternal.prop('checked', 'checked');
+  });
+
+  describe('Behaviour of userExternal checkbox when', () => {
+    it('matches email as internal', (done) => {
+      expect($warningMessage.hasClass('hidden')).toBeTruthy();
+
+      $userEmail.val('test@').trigger('input');
+
+      expect($userExternal.prop('checked')).toBeFalsy();
+      expect($warningMessage.hasClass('hidden')).toBeFalsy();
+      done();
+    });
+
+    it('matches email as external', (done) => {
+      expect($warningMessage.hasClass('hidden')).toBeTruthy();
+
+      $userEmail.val('test.ext@').trigger('input');
+
+      expect($userExternal.prop('checked')).toBeTruthy();
+      expect($warningMessage.hasClass('hidden')).toBeTruthy();
+      done();
+    });
+  });
+});

spec/models/application_setting_spec.rb

@@ -538,4 +538,28 @@ describe ApplicationSetting do
       expect(setting.allow_signup?).to be_falsey
     end
   end
+
+  describe '#user_default_internal_regex_enabled?' do
+    using RSpec::Parameterized::TableSyntax
+
+    where(:user_default_external, :user_default_internal_regex, :result) do
+      false | nil                        | false
+      false | ''                         | false
+      false | '^(?:(?!\.ext@).)*$\r?\n?' | false
+      true  | ''                         | false
+      true  | nil                        | false
+      true  | '^(?:(?!\.ext@).)*$\r?\n?' | true
+    end
+
+    with_them do
+      before do
+        setting.update(user_default_external: user_default_external)
+        setting.update(user_default_internal_regex: user_default_internal_regex)
+      end
+
+      subject { setting.user_default_internal_regex_enabled? }
+
+      it { is_expected.to eq(result) }
+    end
+  end
 end

spec/services/users/build_service_spec.rb

@@ -13,6 +13,59 @@ describe Users::BuildService do
       it 'returns a valid user' do
         expect(service.execute).to be_valid
       end
+
+      context 'with "user_default_external" application setting' do
+        using RSpec::Parameterized::TableSyntax
+
+        where(:user_default_external, :external, :email, :user_default_internal_regex, :result) do
+          true  | nil   | 'fl@example.com'        | nil                     | true
+          true  | true  | 'fl@example.com'        | nil                     | true
+          true  | false | 'fl@example.com'        | nil                     | false
+
+          true  | nil   | 'fl@example.com'        | ''                      | true
+          true  | true  | 'fl@example.com'        | ''                      | true
+          true  | false | 'fl@example.com'        | ''                      | false
+
+          true  | nil   | 'fl@example.com'        | '^(?:(?!\.ext@).)*$\r?' | false
+          true  | true  | 'fl@example.com'        | '^(?:(?!\.ext@).)*$\r?' | true
+          true  | false | 'fl@example.com'        | '^(?:(?!\.ext@).)*$\r?' | false
+
+          true  | nil   | 'tester.ext@domain.com' | '^(?:(?!\.ext@).)*$\r?' | true
+          true  | true  | 'tester.ext@domain.com' | '^(?:(?!\.ext@).)*$\r?' | true
+          true  | false | 'tester.ext@domain.com' | '^(?:(?!\.ext@).)*$\r?' | false
+
+          false | nil   | 'fl@example.com'        | nil                     | false
+          false | true  | 'fl@example.com'        | nil                     | true
+          false | false | 'fl@example.com'        | nil                     | false
+
+          false | nil   | 'fl@example.com'        | ''                      | false
+          false | true  | 'fl@example.com'        | ''                      | true
+          false | false | 'fl@example.com'        | ''                      | false
+
+          false | nil   | 'fl@example.com'        | '^(?:(?!\.ext@).)*$\r?' | false
+          false | true  | 'fl@example.com'        | '^(?:(?!\.ext@).)*$\r?' | true
+          false | false | 'fl@example.com'        | '^(?:(?!\.ext@).)*$\r?' | false
+
+          false | nil   | 'tester.ext@domain.com' | '^(?:(?!\.ext@).)*$\r?' | false
+          false | true  | 'tester.ext@domain.com' | '^(?:(?!\.ext@).)*$\r?' | true
+          false | false | 'tester.ext@domain.com' | '^(?:(?!\.ext@).)*$\r?' | false
+        end
+
+        with_them do
+          before do
+            stub_application_setting(user_default_external: user_default_external)
+            stub_application_setting(user_default_internal_regex: user_default_internal_regex)
+
+            params.merge!({ external: external, email: email }.compact)
+          end
+
+          subject(:user) { service.execute }
+
+          it 'correctly sets user.external' do
+            expect(user.external).to eq(result)
+          end
+        end
+      end
     end
 
     context 'with non admin user' do
@@ -50,6 +103,59 @@ describe Users::BuildService do
           expect(service.execute).to be_confirmed
         end
       end
+
+      context 'with "user_default_external" application setting' do
+        using RSpec::Parameterized::TableSyntax
+
+        where(:user_default_external, :external, :email, :user_default_internal_regex, :result) do
+          true  | nil   | 'fl@example.com'        | nil                     | true
+          true  | true  | 'fl@example.com'        | nil                     | true
+          true  | false | 'fl@example.com'        | nil                     | true
+
+          true  | nil   | 'fl@example.com'        | ''                      | true
+          true  | true  | 'fl@example.com'        | ''                      | true
+          true  | false | 'fl@example.com'        | ''                      | true
+
+          true  | nil   | 'fl@example.com'        | '^(?:(?!\.ext@).)*$\r?' | true
+          true  | true  | 'fl@example.com'        | '^(?:(?!\.ext@).)*$\r?' | true
+          true  | false | 'fl@example.com'        | '^(?:(?!\.ext@).)*$\r?' | true
+
+          true  | nil   | 'tester.ext@domain.com' | '^(?:(?!\.ext@).)*$\r?' | true
+          true  | true  | 'tester.ext@domain.com' | '^(?:(?!\.ext@).)*$\r?' | true
+          true  | false | 'tester.ext@domain.com' | '^(?:(?!\.ext@).)*$\r?' | true
+
+          false | nil   | 'fl@example.com'        | nil                     | false
+          false | true  | 'fl@example.com'        | nil                     | false
+          false | false | 'fl@example.com'        | nil                     | false
+
+          false | nil   | 'fl@example.com'        | ''                      | false
+          false | true  | 'fl@example.com'        | ''                      | false
+          false | false | 'fl@example.com'        | ''                      | false
+
+          false | nil   | 'fl@example.com'        | '^(?:(?!\.ext@).)*$\r?' | false
+          false | true  | 'fl@example.com'        | '^(?:(?!\.ext@).)*$\r?' | false
+          false | false | 'fl@example.com'        | '^(?:(?!\.ext@).)*$\r?' | false
+
+          false | nil   | 'tester.ext@domain.com' | '^(?:(?!\.ext@).)*$\r?' | false
+          false | true  | 'tester.ext@domain.com' | '^(?:(?!\.ext@).)*$\r?' | false
+          false | false | 'tester.ext@domain.com' | '^(?:(?!\.ext@).)*$\r?' | false
+        end
+
+        with_them do
+          before do
+            stub_application_setting(user_default_external: user_default_external)
+            stub_application_setting(user_default_internal_regex: user_default_internal_regex)
+
+            params.merge!({ external: external, email: email }.compact)
+          end
+
+          subject(:user) { service.execute }
+
+          it 'sets the value of Gitlab::CurrentSettings.user_default_external' do
+            expect(user.external).to eq(result)
+          end
+        end
+      end
     end
   end
 end

spec/validators/js_regex_validator_spec.rb

+require 'spec_helper'
+
+describe JsRegexValidator do
+  describe '#validates_each' do
+    using RSpec::Parameterized::TableSyntax
+
+    let(:validator) { described_class.new(attributes: [:user_default_internal_regex]) }
+    let(:application_setting) { build(:application_setting, user_default_external: true) }
+
+    where(:user_default_internal_regex, :result) do
+      nil            | []
+      ''             | []
+      '(?#comment)'  | ['Regex Pattern (?#comment) can not be expressed in Javascript']
+      '(?(a)b|c)'    | ['invalid conditional pattern: /(?(a)b|c)/i']
+      '[a-z&&[^uo]]' | ["Dropped unsupported set intersection '[a-z&&[^uo]]' at index 0",
+                        "Dropped unsupported nested negative set data '[^uo]' at index 6"]
+    end
+
+    with_them do
+      it 'generates correct errors' do
+        validator.validate_each(application_setting, :user_default_internal_regex, user_default_internal_regex)
+
+        expect(application_setting.errors[:user_default_internal_regex]).to eq result
+      end
+    end
+  end
+end