Automatic merge of gitlab-org/gitlab-ce master

app/assets/stylesheets/pages/projects.scss

@@ -67,6 +67,10 @@
   }
 }
 
+.classification-label {
+  background-color: $red-500;
+}
+
 .toggle-wrapper {
   margin-top: 5px;
 }

app/controllers/admin/application_settings_controller.rb

@@ -124,7 +124,9 @@ class Admin::ApplicationSettingsController < Admin::ApplicationController
   end
 
   def visible_application_setting_attributes
-    ApplicationSettingsHelper.visible_attributes + [
+    [
+      *::ApplicationSettingsHelper.visible_attributes,
+      *::ApplicationSettingsHelper.external_authorization_service_attributes,
       :domain_blacklist_file,
       disabled_oauth_sign_in_sources: [],
       import_sources: [],

app/controllers/concerns/project_unauthorized.rb

 # frozen_string_literal: true
 
 module ProjectUnauthorized
-  extend ActiveSupport::Concern
-
-  # EE would override this
   def project_unauthorized_proc
-    # no-op
+    lambda do |project|
+      if project
+        label = project.external_authorization_classification_label
+        rejection_reason = nil
+
+        unless ::Gitlab::ExternalAuthorization.access_allowed?(current_user, label)
+          rejection_reason = ::Gitlab::ExternalAuthorization.rejection_reason(current_user, label)
+          rejection_reason ||= _('External authorization denied access to this project')
+        end
+
+        if rejection_reason
+          access_denied!(rejection_reason)
+        end
+      end
+    end
   end
 end
 

app/controllers/projects_controller.rb

@@ -343,6 +343,7 @@ class ProjectsController < Projects::ApplicationController
       :container_registry_enabled,
       :default_branch,
       :description,
+      :external_authorization_classification_label,
       :import_url,
       :issues_tracker,
       :issues_tracker_id,

app/helpers/application_settings_helper.rb

@@ -119,6 +119,39 @@ module ApplicationSettingsHelper
     options_for_select(options, selected)
   end
 
+  def external_authorization_description
+    _("If enabled, access to projects will be validated on an external service"\
+        " using their classification label.")
+  end
+
+  def external_authorization_timeout_help_text
+    _("Time in seconds GitLab will wait for a response from the external "\
+        "service. When the service does not respond in time, access will be "\
+        "denied.")
+  end
+
+  def external_authorization_url_help_text
+    _("When leaving the URL blank, classification labels can still be "\
+        "specified without disabling cross project features or performing "\
+        "external authorization checks.")
+  end
+
+  def external_authorization_client_certificate_help_text
+    _("The X509 Certificate to use when mutual TLS is required to communicate "\
+        "with the external authorization service. If left blank, the server "\
+        "certificate is still validated when accessing over HTTPS.")
+  end
+
+  def external_authorization_client_key_help_text
+    _("The private key to use when a client certificate is provided. This value "\
+        "is encrypted at rest.")
+  end
+
+  def external_authorization_client_pass_help_text
+    _("The passphrase required to decrypt the private key. This is optional "\
+        "and the value is encrypted at rest.")
+  end
+
   def visible_attributes
     [
       :admin_notification_email,
@@ -237,6 +270,18 @@ module ApplicationSettingsHelper
     ]
   end
 
+  def external_authorization_service_attributes
+    [
+      :external_auth_client_cert,
+      :external_auth_client_key,
+      :external_auth_client_key_pass,
+      :external_authorization_service_default_label,
+      :external_authorization_service_enabled,
+      :external_authorization_service_timeout,
+      :external_authorization_service_url
+    ]
+  end
+
   def expanded_by_default?
     Rails.env.test?
   end

app/helpers/projects_helper.rb

@@ -305,6 +305,16 @@ module ProjectsHelper
     @path.present?
   end
 
+  def external_classification_label_help_message
+    default_label = ::Gitlab::CurrentSettings.current_application_settings
+                      .external_authorization_service_default_label
+
+    s_(
+      "ExternalAuthorizationService|When no classification label is set the "\
+        "default label `%{default_label}` will be used."
+    ) % { default_label: default_label }
+  end
+
   private
 
   def get_project_nav_tabs(project, current_user)

app/models/application_setting.rb

@@ -213,6 +213,40 @@ class ApplicationSetting < ApplicationRecord
 
   validate :terms_exist, if: :enforce_terms?
 
+  validates :external_authorization_service_default_label,
+            presence: true,
+            if: :external_authorization_service_enabled
+
+  validates :external_authorization_service_url,
+            url: true, allow_blank: true,
+            if: :external_authorization_service_enabled
+
+  validates :external_authorization_service_timeout,
+            numericality: { greater_than: 0, less_than_or_equal_to: 10 },
+            if: :external_authorization_service_enabled
+
+  validates :external_auth_client_key,
+            presence: true,
+            if: -> (setting) { setting.external_auth_client_cert.present? }
+
+  validates_with X509CertificateCredentialsValidator,
+                 certificate: :external_auth_client_cert,
+                 pkey: :external_auth_client_key,
+                 pass: :external_auth_client_key_pass,
+                 if: -> (setting) { setting.external_auth_client_cert.present? }
+
+  attr_encrypted :external_auth_client_key,
+                 mode: :per_attribute_iv,
+                 key: Settings.attr_encrypted_db_key_base_truncated,
+                 algorithm: 'aes-256-gcm',
+                 encode: true
+
+  attr_encrypted :external_auth_client_key_pass,
+                 mode: :per_attribute_iv,
+                 key: Settings.attr_encrypted_db_key_base_truncated,
+                 algorithm: 'aes-256-gcm',
+                 encode: true
+
   before_validation :ensure_uuid!
   before_validation :strip_sentry_values
 

app/models/issue.rb

@@ -230,7 +230,13 @@ class Issue < ApplicationRecord
   def visible_to_user?(user = nil)
     return false unless project && project.feature_available?(:issues, user)
 
-    user ? readable_by?(user) : publicly_visible?
+    return publicly_visible? unless user
+
+    return false unless readable_by?(user)
+
+    user.full_private_access? ||
+      ::Gitlab::ExternalAuthorization.access_allowed?(
+        user, project.external_authorization_classification_label)
   end
 
   def check_for_spam?
@@ -298,7 +304,7 @@ class Issue < ApplicationRecord
 
   # Returns `true` if this Issue is visible to everybody.
   def publicly_visible?
-    project.public? && !confidential?
+    project.public? && !confidential? && !::Gitlab::ExternalAuthorization.enabled?
   end
 
   def expire_etag_cache

app/models/project.rb

@@ -2062,6 +2062,11 @@ class Project < ApplicationRecord
     fetch_branch_allows_collaboration(user, branch_name)
   end
 
+  def external_authorization_classification_label
+    super || ::Gitlab::CurrentSettings.current_application_settings
+               .external_authorization_service_default_label
+  end
+
   def licensed_features
     []
   end

app/policies/base_policy.rb

@@ -22,7 +22,14 @@ class BasePolicy < DeclarativePolicy::Base
     Gitlab::CurrentSettings.current_application_settings.restricted_visibility_levels.include?(Gitlab::VisibilityLevel::PUBLIC)
   end
 
-  # This is prevented in some cases in `gitlab-ee`
+  condition(:external_authorization_enabled, scope: :global, score: 0) do
+    ::Gitlab::ExternalAuthorization.perform_check?
+  end
+
+  rule { external_authorization_enabled & ~full_private_access }.policy do
+    prevent :read_cross_project
+  end
+
   rule { default }.enable :read_cross_project
 end
 

app/policies/project_policy.rb

@@ -89,6 +89,15 @@ class ProjectPolicy < BasePolicy
     ::Gitlab::CurrentSettings.current_application_settings.mirror_available
   end
 
+  with_scope :subject
+  condition(:classification_label_authorized, score: 32) do
+    ::Gitlab::ExternalAuthorization.access_allowed?(
+      @user,
+      @subject.external_authorization_classification_label,
+      @subject.full_path
+    )
+  end
+
   # We aren't checking `:read_issue` or `:read_merge_request` in this case
   # because it could be possible for a user to see an issuable-iid
   # (`:read_issue_iid` or `:read_merge_request_iid`) but then wouldn't be
@@ -417,6 +426,25 @@ class ProjectPolicy < BasePolicy
 
   rule { ~can_have_multiple_clusters & has_clusters }.prevent :add_cluster
 
+  rule { ~can?(:read_cross_project) & ~classification_label_authorized }.policy do
+    # Preventing access here still allows the projects to be listed. Listing
+    # projects doesn't check the `:read_project` ability. But instead counts
+    # on the `project_authorizations` table.
+    #
+    # All other actions should explicitly check read project, which would
+    # trigger the `classification_label_authorized` condition.
+    #
+    # `:read_project_for_iids` is not prevented by this condition, as it is
+    # used for cross-project reference checks.
+    prevent :guest_access
+    prevent :public_access
+    prevent :public_user_access
+    prevent :reporter_access
+    prevent :developer_access
+    prevent :maintainer_access
+    prevent :owner_access
+  end
+
   private
 
   def team_member?

app/services/application_settings/update_service.rb

@@ -2,9 +2,17 @@
 
 module ApplicationSettings
   class UpdateService < ApplicationSettings::BaseService
+    include ValidatesClassificationLabel
+
     attr_reader :params, :application_setting
 
     def execute
+      validate_classification_label(application_setting, :external_authorization_service_default_label)
+
+      if application_setting.errors.any?
+        return false
+      end
+
       update_terms(@params.delete(:terms))
 
       if params.key?(:performance_bar_allowed_group_path)

app/services/concerns/validates_classification_label.rb

+# frozen_string_literal: true
+
+module ValidatesClassificationLabel
+  def validate_classification_label(record, attribute_name)
+    return unless ::Gitlab::ExternalAuthorization.enabled?
+    return unless classification_label_change?(record, attribute_name)
+
+    new_label = params[attribute_name].presence
+    new_label ||= ::Gitlab::CurrentSettings.current_application_settings
+                    .external_authorization_service_default_label
+
+    unless ::Gitlab::ExternalAuthorization.access_allowed?(current_user, new_label)
+      reason = rejection_reason_for_label(new_label)
+      message = s_('ClassificationLabelUnavailable|is unavailable: %{reason}') % { reason: reason }
+      record.errors.add(attribute_name, message)
+    end
+  end
+
+  def rejection_reason_for_label(label)
+    reason_from_service = ::Gitlab::ExternalAuthorization.rejection_reason(current_user, label).presence
+    reason_from_service || _("Access to '%{classification_label}' not allowed") % { classification_label: label }
+  end
+
+  def classification_label_change?(record, attribute_name)
+    params.key?(attribute_name) || record.new_record?
+  end
+end

app/services/projects/create_service.rb

@@ -2,6 +2,8 @@
 
 module Projects
   class CreateService < BaseService
+    include ValidatesClassificationLabel
+
     def initialize(user, params)
       @current_user, @params = user, params.dup
       @skip_wiki = @params.delete(:skip_wiki)
@@ -45,6 +47,8 @@ module Projects
       relations_block&.call(@project)
       yield(@project) if block_given?
 
+      validate_classification_label(@project, :external_authorization_classification_label)
+
       # If the block added errors, don't try to save the project
       return @project if @project.errors.any?
 

app/services/projects/update_service.rb

@@ -3,6 +3,7 @@
 module Projects
   class UpdateService < BaseService
     include UpdateVisibilityLevel
+    include ValidatesClassificationLabel
 
     ValidationError = Class.new(StandardError)
 
@@ -14,6 +15,8 @@ module Projects
 
       yield if block_given?
 
+      validate_classification_label(project, :external_authorization_classification_label)
+
       # If the block added errors, don't try to save the project
       return update_failed! if project.errors.any?
 

app/validators/x509_certificate_credentials_validator.rb

+# frozen_string_literal: true
+
+# X509CertificateCredentialsValidator
+#
+# Custom validator to check if certificate-attribute was signed using the
+# private key stored in an attrebute.
+#
+# This can be used as an `ActiveModel::Validator` as follows:
+#
+#   validates_with X509CertificateCredentialsValidator,
+#                  certificate: :client_certificate,
+#                  pkey: :decrypted_private_key,
+#                  pass: :decrypted_passphrase
+#
+#
+# Required attributes:
+# - certificate: The name of the accessor that returns the certificate to check
+# - pkey: The name of the accessor that returns the private key
+# Optional:
+# - pass: The name of the accessor that returns the passphrase to decrypt the
+#         private key
+class X509CertificateCredentialsValidator < ActiveModel::Validator
+  def initialize(*args)
+    super
+
+    # We can't validate if we don't have a private key or certificate attributes
+    # in which case this validator is useless.
+    if options[:pkey].nil? || options[:certificate].nil?
+      raise 'Provide at least `certificate` and `pkey` attribute names'
+    end
+  end
+
+  def validate(record)
+    unless certificate = read_certificate(record)
+      record.errors.add(options[:certificate], _('is not a valid X509 certificate.'))
+    end
+
+    unless private_key = read_private_key(record)
+      record.errors.add(options[:pkey], _('could not read private key, is the passphrase correct?'))
+    end
+
+    return if private_key.nil? || certificate.nil?
+
+    unless certificate.public_key.fingerprint == private_key.public_key.fingerprint
+      record.errors.add(options[:pkey], _('private key does not match certificate.'))
+    end
+  end
+
+  private
+
+  def read_private_key(record)
+    OpenSSL::PKey.read(pkey(record).to_s, pass(record).to_s)
+  rescue OpenSSL::PKey::PKeyError, ArgumentError
+    # When the primary key could not be read, an ArgumentError is raised.
+    # This hapens when the passed key is not valid or the passphrase is incorrect
+    nil
+  end
+
+  def read_certificate(record)
+    OpenSSL::X509::Certificate.new(certificate(record).to_s)
+  rescue OpenSSL::X509::CertificateError
+    nil
+  end
+
+  # rubocop:disable GitlabSecurity/PublicSend
+  #
+  # Allowing `#public_send` here because we don't want the validator to really
+  # care about the names of the attributes or where they come from.
+  #
+  # The credentials are mostly stored encrypted so we need to go through the
+  # accessors to get the values, `read_attribute` bypasses those.
+  def certificate(record)
+    record.public_send(options[:certificate])
+  end
+
+  def pkey(record)
+    record.public_send(options[:pkey])
+  end
+
+  def pass(record)
+    return unless options[:pass]
+
+    record.public_send(options[:pass])
+  end
+  # rubocop:enable GitlabSecurity/PublicSend
+end

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

+%section.settings.as-external-auth.no-animate#js-external-auth-settings{ class: ('expanded' if expanded) }
+  .settings-header
+    %h4
+      = _('External authentication')
+    %button.btn.js-settings-toggle{ type: 'button' }
+      = expanded ? 'Collapse' : 'Expand'
+    %p
+    = _('External Classification Policy Authorization')
+  .settings-content
+
+    = form_for @application_setting, url: admin_application_settings_path(anchor: 'js-external-auth-settings'), html: { class: 'fieldset-form' } do |f|
+      = form_errors(@application_setting)
+
+      %fieldset
+        .form-group
+          .form-check
+            = f.check_box :external_authorization_service_enabled, class: 'form-check-input'
+            = f.label :external_authorization_service_enabled, class: 'form-check-label' do
+              = _('Enable classification control using an external service')
+          %span.form-text.text-muted
+            = external_authorization_description
+            = link_to icon('question-circle'), help_page_path('user/admin_area/settings/external_authorization')
+        .form-group
+          = f.label :external_authorization_service_url, _('Service URL'), class: 'label-bold'
+          = f.text_field :external_authorization_service_url, class: 'form-control'
+          %span.form-text.text-muted
+            = external_authorization_url_help_text
+        .form-group
+          = f.label :external_authorization_service_timeout, _('External authorization request timeout'), class: 'label-bold'
+          = f.number_field :external_authorization_service_timeout, class: 'form-control', min: 0.001, max: 10, step: 0.001
+          %span.form-text.text-muted
+            = external_authorization_timeout_help_text
+          = f.label :external_auth_client_cert, _('Client authentication certificate'), class: 'label-bold'
+          = f.text_area :external_auth_client_cert, class: 'form-control'
+          %span.form-text.text-muted
+            = external_authorization_client_certificate_help_text
+        .form-group
+          = f.label :external_auth_client_key, _('Client authentication key'), class: 'label-bold'
+          = f.text_area :external_auth_client_key, class: 'form-control'
+          %span.form-text.text-muted
+            = external_authorization_client_key_help_text
+        .form-group
+          = f.label :external_auth_client_key_pass, _('Client authentication key password'), class: 'label-bold'
+          = f.password_field :external_auth_client_key_pass, class: 'form-control'
+          %span.form-text.text-muted
+            = external_authorization_client_pass_help_text
+        .form-group
+          = f.label :external_authorization_service_default_label, _('Default classification label'), class: 'label-bold'
+          = f.text_field :external_authorization_service_default_label, class: 'form-control'
+
+      = f.submit 'Save changes', class: "btn btn-success"

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

@@ -68,7 +68,7 @@
   .settings-content
     = render 'terms'
 
-= render_if_exists 'admin/application_settings/external_authorization_service_form', expanded: expanded_by_default?
+= render 'admin/application_settings/external_authorization_service_form', expanded: expanded_by_default?
 
 %section.settings.as-terminal.no-animate#js-terminal-settings{ class: ('expanded' if expanded_by_default?) }
   .settings-header

app/views/layouts/nav/_classification_level_banner.html.haml

+- if ::Gitlab::ExternalAuthorization.enabled? && @project
+  = content_for :header_content do
+    %span.badge.color-label.classification-label.has-tooltip{ title: s_('ExternalAuthorizationService|Classification label') }
+      = sprite_icon('lock-open', size: 8, css_class: 'inline')
+      = @project.external_authorization_classification_label

app/views/projects/_classification_policy_settings.html.haml

+- if ::Gitlab::ExternalAuthorization.enabled?
+  .form-group
+    = f.label :external_authorization_classification_label, class: 'label-bold' do
+      = s_('ExternalAuthorizationService|Classification Label')
+      %span.light (optional)
+    = f.text_field :external_authorization_classification_label, class: "form-control"
+    %span.form-text.text-muted
+      = external_classification_label_help_message

app/views/projects/edit.html.haml

@@ -32,7 +32,7 @@
               %span.light (optional)
             = f.text_area :description, class: "form-control", rows: 3, maxlength: 250
 
-          = render_if_exists 'projects/classification_policy_settings', f: f
+          = render 'projects/classification_policy_settings', f: f
 
         = render_if_exists 'shared/repository_size_limit_setting', form: f, type: :project
 

changelogs/unreleased/57131-external_auth_to_core.yml

+---
+title: Move "Authorize project access with external service" to Core
+merge_request: 26823
+author:
+type: changed

db/migrate/20171211131502_add_external_classification_authorization_settings_to_appliction_settings.rb

+class AddExternalClassificationAuthorizationSettingsToApplictionSettings < ActiveRecord::Migration[4.2]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def up
+    add_column_with_default :application_settings,
+                            :external_authorization_service_enabled,
+                            :boolean,
+                            default: false
+    add_column :application_settings,
+               :external_authorization_service_url,
+               :string
+    add_column :application_settings,
+               :external_authorization_service_default_label,
+               :string
+  end
+
+  def down
+    remove_column :application_settings,
+                  :external_authorization_service_default_label
+    remove_column :application_settings,
+                  :external_authorization_service_url
+    remove_column :application_settings,
+                  :external_authorization_service_enabled
+  end
+end

db/migrate/20171218140451_add_external_authorization_service_classification_label_to_projects.rb

+class AddExternalAuthorizationServiceClassificationLabelToProjects < ActiveRecord::Migration[4.2]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  def change
+    add_column :projects,
+               :external_authorization_classification_label,
+               :string
+  end
+end

db/migrate/20180314100728_add_external_authorization_service_timeout_to_application_settings.rb

+class AddExternalAuthorizationServiceTimeoutToApplicationSettings < ActiveRecord::Migration[4.2]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  def up
+    # We can use the regular `add_column` with a default since `application_settings`
+    # is a small table.
+    add_column :application_settings,
+               :external_authorization_service_timeout,
+               :float,
+               default: 0.5
+  end
+
+  def down
+    remove_column :application_settings, :external_authorization_service_timeout
+  end
+end

db/migrate/20180315160435_add_external_auth_mutual_tls_fields_to_project_settings.rb

+class AddExternalAuthMutualTlsFieldsToProjectSettings < ActiveRecord::Migration[4.2]
+  DOWNTIME = false
+
+  def change
+    add_column :application_settings,
+               :external_auth_client_cert, :text
+    add_column :application_settings,
+               :encrypted_external_auth_client_key, :text
+    add_column :application_settings,
+               :encrypted_external_auth_client_key_iv, :string
+    add_column :application_settings,
+               :encrypted_external_auth_client_key_pass, :string
+    add_column :application_settings,
+               :encrypted_external_auth_client_key_pass_iv, :string
+  end
+end

lib/api/entities.rb

@@ -277,6 +277,7 @@ module API
       expose :statistics, using: 'API::Entities::ProjectStatistics', if: -> (project, options) {
         options[:statistics] && Ability.allowed?(options[:current_user], :read_statistics, project)
       }
+      expose :external_authorization_classification_label
 
       # rubocop: disable CodeReuse/ActiveRecord
       def self.preload_relation(projects_relation, options = {})
@@ -1116,6 +1117,8 @@ module API
       expose(:default_snippet_visibility) { |setting, _options| Gitlab::VisibilityLevel.string_level(setting.default_snippet_visibility) }
       expose(:default_group_visibility) { |setting, _options| Gitlab::VisibilityLevel.string_level(setting.default_group_visibility) }
 
+      expose(*::ApplicationSettingsHelper.external_authorization_service_attributes)
+
       # support legacy names, can be removed in v5
       expose :password_authentication_enabled_for_web, as: :password_authentication_enabled
       expose :password_authentication_enabled_for_web, as: :signin_enabled

lib/api/helpers/projects_helpers.rb

@@ -29,13 +29,13 @@ module API
             optional :printing_merge_request_link_enabled, type: Boolean, desc: 'Show link to create/view merge request when pushing from the command line'
             optional :merge_method, type: String, values: %w(ff rebase_merge merge), desc: 'The merge method used when merging merge requests'
             optional :initialize_with_readme, type: Boolean, desc: "Initialize a project with a README.md"
+            optional :external_authorization_classification_label, type: String, desc: 'The classification label for the project'
           end
 
           if Gitlab.ee?
             params :optional_project_params_ee do
               optional :repository_storage, type: String, desc: 'Which storage shard the repository is on. Available only to admins'
               optional :approvals_before_merge, type: Integer, desc: 'How many approvers should approve merge request by default'
-              optional :external_authorization_classification_label, type: String, desc: 'The classification label for the project'
               optional :mirror, type: Boolean, desc: 'Enables pull mirroring in a project'
               optional :mirror_trigger_builds, type: Boolean, desc: 'Pull mirroring triggers builds'
             end
@@ -72,7 +72,8 @@ module API
           :tag_list,
           :visibility,
           :wiki_enabled,
-          :avatar
+          :avatar,
+          :external_authorization_classification_label
         ]
       end
     end

lib/api/settings.rb

@@ -167,7 +167,9 @@ module API
         optional :usage_ping_enabled, type: Boolean, desc: 'Every week GitLab will report license usage back to GitLab, Inc.'
       end
 
-      optional_attributes = ::ApplicationSettingsHelper.visible_attributes << :performance_bar_allowed_group_id
+      optional_attributes = [*::ApplicationSettingsHelper.visible_attributes,
+                             *::ApplicationSettingsHelper.external_authorization_service_attributes,
+                             :performance_bar_allowed_group_id]
 
       if Gitlab.ee?
         optional_attributes += EE::ApplicationSettingsHelper.possible_licensed_attributes

lib/gitlab/external_authorization.rb

+# frozen_string_literal: true
+
+module Gitlab
+  module ExternalAuthorization
+    extend ExternalAuthorization::Config
+
+    RequestFailed = Class.new(StandardError)
+
+    def self.access_allowed?(user, label, project_path = nil)
+      return true unless perform_check?
+      return false unless user
+
+      access_for_user_to_label(user, label, project_path).has_access?
+    end
+
+    def self.rejection_reason(user, label)
+      return unless enabled?
+      return unless user
+
+      access_for_user_to_label(user, label, nil).reason
+    end
+
+    def self.access_for_user_to_label(user, label, project_path)
+      if RequestStore.active?
+        RequestStore.fetch("external_authorisation:user-#{user.id}:label-#{label}") do
+          load_access(user, label, project_path)
+        end
+      else
+        load_access(user, label, project_path)
+      end
+    end
+
+    def self.load_access(user, label, project_path)
+      access = ::Gitlab::ExternalAuthorization::Access.new(user, label).load!
+      ::Gitlab::ExternalAuthorization::Logger.log_access(access, project_path)
+
+      access
+    end
+  end
+end

lib/gitlab/external_authorization/access.rb

+# frozen_string_literal: true
+
+module Gitlab
+  module ExternalAuthorization
+    class Access
+      attr_reader :user,
+                  :reason,
+                  :loaded_at,
+                  :label,
+                  :load_type
+
+      def initialize(user, label)
+        @user, @label = user, label
+      end
+
+      def loaded?
+        loaded_at && (loaded_at > ExternalAuthorization::Cache::VALIDITY_TIME.ago)
+      end
+
+      def has_access?
+        @access
+      end
+
+      def load!
+        load_from_cache
+        load_from_service unless loaded?
+        self
+      end
+
+      private
+
+      def load_from_cache
+        @load_type = :cache
+        @access, @reason, @loaded_at = cache.load
+      end
+
+      def load_from_service
+        @load_type = :request
+        response = Client.new(@user, @label).request_access
+        @access = response.successful?
+        @reason = response.reason
+        @loaded_at = Time.now
+        cache.store(@access, @reason, @loaded_at) if response.valid?
+      rescue ::Gitlab::ExternalAuthorization::RequestFailed => e
+        @access = false
+        @reason = e.message
+        @loaded_at = Time.now
+      end
+
+      def cache
+        @cache ||= ExternalAuthorization::Cache.new(@user, @label)
+      end
+    end
+  end
+end

lib/gitlab/external_authorization/cache.rb

+# frozen_string_literal: true
+
+module Gitlab
+  module ExternalAuthorization
+    class Cache
+      VALIDITY_TIME = 6.hours
+
+      def initialize(user, label)
+        @user, @label = user, label
+      end
+
+      def load
+        @access, @reason, @refreshed_at = ::Gitlab::Redis::Cache.with do |redis|
+          redis.hmget(cache_key, :access, :reason, :refreshed_at)
+        end
+
+        [access, reason, refreshed_at]
+      end
+
+      def store(new_access, new_reason, new_refreshed_at)
+        ::Gitlab::Redis::Cache.with do |redis|
+          redis.pipelined do
+            redis.mapped_hmset(
+              cache_key,
+              {
+                access: new_access.to_s,
+                reason: new_reason.to_s,
+                refreshed_at: new_refreshed_at.to_s
+              }
+            )
+
+            redis.expire(cache_key, VALIDITY_TIME)
+          end
+        end
+      end
+
+      private
+
+      def access
+        ::Gitlab::Utils.to_boolean(@access)
+      end
+
+      def reason
+        # `nil` if the cached value was an empty string
+        return unless @reason.present?
+
+        @reason
+      end
+
+      def refreshed_at
+        # Don't try to parse a time if there was no cache
+        return unless @refreshed_at.present?
+
+        Time.parse(@refreshed_at)
+      end
+
+      def cache_key
+        "external_authorization:user-#{@user.id}:label-#{@label}"
+      end
+    end
+  end
+end

lib/gitlab/external_authorization/client.rb

+# frozen_string_literal: true
+
+Excon.defaults[:ssl_verify_peer] = false
+
+module Gitlab
+  module ExternalAuthorization
+    class Client
+      include ExternalAuthorization::Config
+
+      REQUEST_HEADERS = {
+        'Content-Type' => 'application/json',
+        'Accept' => 'application/json'
+      }.freeze
+
+      def initialize(user, label)
+        @user, @label = user, label
+      end
+
+      def request_access
+        response = Excon.post(
+          service_url,
+          post_params
+        )
+        ::Gitlab::ExternalAuthorization::Response.new(response)
+      rescue Excon::Error => e
+        raise ::Gitlab::ExternalAuthorization::RequestFailed.new(e)
+      end
+
+      private
+
+      def post_params
+        params = { headers: REQUEST_HEADERS,
+                   body: body.to_json,
+                   connect_timeout: timeout,
+                   read_timeout: timeout,
+                   write_timeout: timeout }
+
+        if has_tls?
+          params[:client_cert_data] = client_cert
+          params[:client_key_data] = client_key
+          params[:client_key_pass] = client_key_pass
+        end
+
+        params
+      end
+
+      def body
+        @body ||= begin
+                    body = {
+                      user_identifier: @user.email,
+                      project_classification_label: @label
+                    }
+
+                    if @user.ldap_identity
+                      body[:user_ldap_dn] = @user.ldap_identity.extern_uid
+                    end
+
+                    body
+                  end
+      end
+    end
+  end
+end

lib/gitlab/external_authorization/config.rb

+# frozen_string_literal: true
+
+module Gitlab
+  module ExternalAuthorization
+    module Config
+      extend self
+
+      def timeout
+        application_settings.external_authorization_service_timeout
+      end
+
+      def service_url
+        application_settings.external_authorization_service_url
+      end
+
+      def enabled?
+        application_settings.external_authorization_service_enabled
+      end
+
+      def perform_check?
+        enabled? && service_url.present?
+      end
+
+      def client_cert
+        application_settings.external_auth_client_cert
+      end
+
+      def client_key
+        application_settings.external_auth_client_key
+      end
+
+      def client_key_pass
+        application_settings.external_auth_client_key_pass
+      end
+
+      def has_tls?
+        client_cert.present? && client_key.present?
+      end
+
+      private
+
+      def application_settings
+        ::Gitlab::CurrentSettings.current_application_settings
+      end
+    end
+  end
+end

lib/gitlab/external_authorization/logger.rb

+# frozen_string_literal: true
+
+module Gitlab
+  module ExternalAuthorization
+    class Logger < ::Gitlab::Logger
+      def self.log_access(access, project_path)
+        status = access.has_access? ? "GRANTED" : "DENIED"
+        message = ["#{status} #{access.user.email} access to '#{access.label}'"]
+
+        message << "(#{project_path})" if project_path.present?
+        message << "- #{access.load_type} #{access.loaded_at}" if access.load_type == :cache
+
+        info(message.join(' '))
+      end
+
+      def self.file_name_noext
+        'external-policy-access-control'
+      end
+    end
+  end
+end

lib/gitlab/external_authorization/response.rb

+# frozen_string_literal: true
+
+module Gitlab
+  module ExternalAuthorization
+    class Response
+      include ::Gitlab::Utils::StrongMemoize
+
+      def initialize(excon_response)
+        @excon_response = excon_response
+      end
+
+      def valid?
+        @excon_response && [200, 401, 403].include?(@excon_response.status)
+      end
+
+      def successful?
+        valid? && @excon_response.status == 200
+      end
+
+      def reason
+        parsed_response['reason'] if parsed_response
+      end
+
+      private
+
+      def parsed_response
+        strong_memoize(:parsed_response) { parse_response! }
+      end
+
+      def parse_response!
+        JSON.parse(@excon_response.body)
+      rescue JSON::JSONError
+        # The JSON response is optional, so don't fail when it's missing
+        nil
+      end
+    end
+  end
+end

spec/controllers/admin/application_settings_controller_spec.rb

@@ -85,6 +85,28 @@ describe Admin::ApplicationSettingsController do
       expect(response).to redirect_to(admin_application_settings_path)
       expect(ApplicationSetting.current.receive_max_input_size).to eq(1024)
     end
+
+    context 'external policy classification settings' do
+      let(:settings) do
+        {
+          external_authorization_service_enabled: true,
+          external_authorization_service_url: 'https://custom.service/',
+          external_authorization_service_default_label: 'default',
+          external_authorization_service_timeout: 3,
+          external_auth_client_cert: File.read('spec/fixtures/passphrase_x509_certificate.crt'),
+          external_auth_client_key: File.read('spec/fixtures/passphrase_x509_certificate_pk.key'),
+          external_auth_client_key_pass: "5iveL!fe"
+        }
+      end
+
+      it 'updates settings when the feature is available' do
+        put :update, params: { application_setting: settings }
+
+        settings.each do |attribute, value|
+          expect(ApplicationSetting.current.public_send(attribute)).to eq(value)
+        end
+      end
+    end
   end
 
   describe 'PUT #reset_registration_token' do

spec/controllers/boards/issues_controller_spec.rb

 require 'spec_helper'
 
 describe Boards::IssuesController do
+  include ExternalAuthorizationServiceHelpers
+
   let(:project) { create(:project, :private) }
   let(:board)   { create(:board, project: project) }
   let(:user)    { create(:user) }
@@ -136,6 +138,30 @@ describe Boards::IssuesController do
       end
     end
 
+    context 'with external authorization' do
+      before do
+        sign_in(user)
+        enable_external_authorization_service_check
+      end
+
+      it 'returns a 403 for group boards' do
+        group = create(:group)
+        group_board = create(:board, group: group)
+
+        list_issues(user: user, board: group_board)
+
+        expect(response).to have_gitlab_http_status(403)
+      end
+
+      it 'is successful for project boards' do
+        project_board = create(:board, project: project)
+
+        list_issues(user: user, board: project_board)
+
+        expect(response).to have_gitlab_http_status(200)
+      end
+    end
+
     def list_issues(user:, board:, list: nil)
       sign_in(user)
 

spec/controllers/concerns/project_unauthorized_spec.rb

+require 'spec_helper'
+
+describe ProjectUnauthorized do
+  include ExternalAuthorizationServiceHelpers
+  let(:user) { create(:user) }
+
+  before do
+    sign_in user
+  end
+
+  render_views
+
+  describe '#project_unauthorized_proc' do
+    controller(::Projects::ApplicationController) do
+      def show
+        head :ok
+      end
+    end
+
+    let(:project) { create(:project) }
+
+    before do
+      project.add_developer(user)
+    end
+
+    it 'renders a 200 when the service allows access to the project' do
+      external_service_allow_access(user, project)
+
+      get :show, params: { namespace_id: project.namespace.to_param, id: project.to_param }
+
+      expect(response).to have_gitlab_http_status(200)
+    end
+
+    it 'renders a 403 when the service denies access to the project' do
+      external_service_deny_access(user, project)
+
+      get :show, params: { namespace_id: project.namespace.to_param, id: project.to_param }
+
+      expect(response).to have_gitlab_http_status(403)
+      expect(response.body).to match("External authorization denied access to this project")
+    end
+
+    it 'renders a 404 when the user cannot see the project at all' do
+      other_project = create(:project, :private)
+
+      get :show, params: { namespace_id: other_project.namespace.to_param, id: other_project.to_param }
+
+      expect(response).to have_gitlab_http_status(404)
+    end
+  end
+end

spec/controllers/dashboard/groups_controller_spec.rb

 require 'spec_helper'
 
 describe Dashboard::GroupsController do
+  include ExternalAuthorizationServiceHelpers
+
   let(:user) { create(:user) }
 
   before do
@@ -11,33 +13,43 @@ describe Dashboard::GroupsController do
     expect(described_class).to include(GroupTree)
   end
 
-  it 'only includes projects the user is a member of' do
-    member_of_group = create(:group)
-    member_of_group.add_developer(user)
-    create(:group, :public)
+  describe '#index' do
+    it 'only includes projects the user is a member of' do
+      member_of_group = create(:group)
+      member_of_group.add_developer(user)
+      create(:group, :public)
 
-    get :index
+      get :index
 
-    expect(assigns(:groups)).to contain_exactly(member_of_group)
-  end
+      expect(assigns(:groups)).to contain_exactly(member_of_group)
+    end
 
-  context 'when rendering an expanded hierarchy with public groups you are not a member of', :nested_groups do
-    let!(:top_level_result) { create(:group, name: 'chef-top') }
-    let!(:top_level_a) { create(:group, name: 'top-a') }
-    let!(:sub_level_result_a) { create(:group, name: 'chef-sub-a', parent: top_level_a) }
-    let!(:other_group) { create(:group, name: 'other') }
+    context 'when rendering an expanded hierarchy with public groups you are not a member of', :nested_groups do
+      let!(:top_level_result) { create(:group, name: 'chef-top') }
+      let!(:top_level_a) { create(:group, name: 'top-a') }
+      let!(:sub_level_result_a) { create(:group, name: 'chef-sub-a', parent: top_level_a) }
+      let!(:other_group) { create(:group, name: 'other') }
 
-    before do
-      top_level_result.add_maintainer(user)
-      top_level_a.add_maintainer(user)
+      before do
+        top_level_result.add_maintainer(user)
+        top_level_a.add_maintainer(user)
+      end
+
+      it 'renders only groups the user is a member of when searching hierarchy correctly' do
+        get :index, params: { filter: 'chef' }, format: :json
+
+        expect(response).to have_gitlab_http_status(200)
+        all_groups = [top_level_result, top_level_a, sub_level_result_a]
+        expect(assigns(:groups)).to contain_exactly(*all_groups)
+      end
     end
 
-    it 'renders only groups the user is a member of when searching hierarchy correctly' do
-      get :index, params: { filter: 'chef' }, format: :json
+    it 'works when the external authorization service is enabled' do
+      enable_external_authorization_service_check
+
+      get :index
 
       expect(response).to have_gitlab_http_status(200)
-      all_groups = [top_level_result, top_level_a, sub_level_result_a]
-      expect(assigns(:groups)).to contain_exactly(*all_groups)
     end
   end
 end

spec/controllers/dashboard/labels_controller_spec.rb

@@ -13,13 +13,17 @@ describe Dashboard::LabelsController do
   describe "#index" do
     let!(:unrelated_label) { create(:label, project: create(:project, :public)) }
 
+    subject { get :index, format: :json }
+
     it 'returns global labels for projects the user has a relationship with' do
-      get :index, format: :json
+      subject
 
       expect(json_response).to be_kind_of(Array)
       expect(json_response.size).to eq(1)
       expect(json_response[0]["id"]).to be_nil
       expect(json_response[0]["title"]).to eq(label.title)
     end
+
+    it_behaves_like 'disabled when using an external authorization service'
   end
 end

spec/controllers/dashboard/milestones_controller_spec.rb

@@ -81,5 +81,11 @@ describe Dashboard::MilestonesController do
       expect(response.body).to include("Open\n<span class=\"badge badge-pill\">2</span>")
       expect(response.body).to include("Closed\n<span class=\"badge badge-pill\">0</span>")
     end
+
+    context 'external authorization' do
+      subject { get :index }
+
+      it_behaves_like 'disabled when using an external authorization service'
+    end
   end
 end

spec/controllers/dashboard/projects_controller_spec.rb

 require 'spec_helper'
 
 describe Dashboard::ProjectsController do
-  it_behaves_like 'authenticates sessionless user', :index, :atom
+  include ExternalAuthorizationServiceHelpers
+
+  describe '#index' do
+    context 'user not logged in' do
+      it_behaves_like 'authenticates sessionless user', :index, :atom
+    end
+
+    context 'user logged in' do
+      before do
+        sign_in create(:user)
+      end
+
+      context 'external authorization' do
+        it 'works when the external authorization service is enabled' do
+          enable_external_authorization_service_check
+
+          get :index
+
+          expect(response).to have_gitlab_http_status(200)
+        end
+      end
+    end
+  end
 
   context 'json requests' do
     render_views

spec/controllers/dashboard/todos_controller_spec.rb

@@ -105,6 +105,12 @@ describe Dashboard::TodosController do
         end
       end
     end
+
+    context 'external authorization' do
+      subject { get :index }
+
+      it_behaves_like 'disabled when using an external authorization service'
+    end
   end
 
   describe 'PATCH #restore' do

spec/controllers/groups/avatars_controller_spec.rb

 require 'spec_helper'
 
 describe Groups::AvatarsController do
+  include ExternalAuthorizationServiceHelpers
+
   let(:user)  { create(:user) }
   let(:group) { create(:group, avatar: fixture_file_upload("spec/fixtures/dk.png", "image/png")) }
 
@@ -15,4 +17,12 @@ describe Groups::AvatarsController do
     expect(@group.avatar.present?).to be_falsey
     expect(@group).to be_valid
   end
+
+  it 'works when external authorization service is enabled' do
+    enable_external_authorization_service_check
+
+    delete :destroy, params: { group_id: group }
+
+    expect(response).to have_gitlab_http_status(302)
+  end
 end

spec/controllers/groups/boards_controller_spec.rb

@@ -82,6 +82,10 @@ describe Groups::BoardsController do
       end
     end
 
+    it_behaves_like 'disabled when using an external authorization service' do
+      subject { list_boards }
+    end
+
     def list_boards(format: :html)
       get :index, params: { group_id: group }, format: format
     end
@@ -160,6 +164,10 @@ describe Groups::BoardsController do
       end
     end
 
+    it_behaves_like 'disabled when using an external authorization service' do
+      subject { read_board board: board }
+    end
+
     def read_board(board:, format: :html)
       get :show, params: {
                    group_id: group,

spec/controllers/groups/children_controller_spec.rb

 require 'spec_helper'
 
 describe Groups::ChildrenController do
+  include ExternalAuthorizationServiceHelpers
+
   let(:group) { create(:group, :public) }
   let(:user) { create(:user) }
   let!(:group_member) { create(:group_member, group: group, user: user) }
@@ -317,5 +319,15 @@ describe Groups::ChildrenController do
         end
       end
     end
+
+    context 'external authorization' do
+      it 'works when external authorization service is enabled' do
+        enable_external_authorization_service_check
+
+        get :index, params: { group_id: group }, format: :json
+
+        expect(response).to have_gitlab_http_status(200)
+      end
+    end
   end
 end

spec/controllers/groups/group_members_controller_spec.rb

 require 'spec_helper'
 
 describe Groups::GroupMembersController do
+  include ExternalAuthorizationServiceHelpers
+
   let(:user)  { create(:user) }
   let(:group) { create(:group, :public, :access_requestable) }
+  let(:membership) { create(:group_member, group: group) }
 
   describe 'GET index' do
     it 'renders index with 200 status code' do
@@ -283,4 +286,87 @@ describe Groups::GroupMembersController do
       end
     end
   end
+
+  context 'with external authorization enabled' do
+    before do
+      enable_external_authorization_service_check
+      group.add_owner(user)
+      sign_in(user)
+    end
+
+    describe 'GET #index' do
+      it 'is successful' do
+        get :index, params: { group_id: group }
+
+        expect(response).to have_gitlab_http_status(200)
+      end
+    end
+
+    describe 'POST #create' do
+      it 'is successful' do
+        post :create, params: { group_id: group, users: user, access_level: Gitlab::Access::GUEST }
+
+        expect(response).to have_gitlab_http_status(302)
+      end
+    end
+
+    describe 'PUT #update' do
+      it 'is successful' do
+        put :update,
+            params: {
+              group_member: { access_level: Gitlab::Access::GUEST },
+              group_id: group,
+              id: membership
+            },
+            format: :js
+
+        expect(response).to have_gitlab_http_status(200)
+      end
+    end
+
+    describe 'DELETE #destroy' do
+      it 'is successful' do
+        delete :destroy, params: { group_id: group, id: membership }
+
+        expect(response).to have_gitlab_http_status(302)
+      end
+    end
+
+    describe 'POST #destroy' do
+      it 'is successful' do
+        sign_in(create(:user))
+
+        post :request_access, params: { group_id: group }
+
+        expect(response).to have_gitlab_http_status(302)
+      end
+    end
+
+    describe 'POST #approve_request_access' do
+      it 'is successful' do
+        access_request = create(:group_member, :access_request, group: group)
+        post :approve_access_request, params: { group_id: group, id: access_request }
+
+        expect(response).to have_gitlab_http_status(302)
+      end
+    end
+
+    describe 'DELETE #leave' do
+      it 'is successful' do
+        group.add_owner(create(:user))
+
+        delete :leave, params: { group_id: group }
+
+        expect(response).to have_gitlab_http_status(302)
+      end
+    end
+
+    describe 'POST #resend_invite' do
+      it 'is successful' do
+        post :resend_invite, params: { group_id: group, id: membership }
+
+        expect(response).to have_gitlab_http_status(302)
+      end
+    end
+  end
 end

spec/controllers/groups/labels_controller_spec.rb

@@ -37,6 +37,12 @@ describe Groups::LabelsController do
         expect(label_ids).to match_array([group_label_1.title, subgroup_label_1.title])
       end
     end
+
+    context 'external authorization' do
+      subject { get :index, params: { group_id: group.to_param } }
+
+      it_behaves_like 'disabled when using an external authorization service'
+    end
   end
 
   describe 'POST #toggle_subscription' do

spec/controllers/groups/milestones_controller_spec.rb

@@ -80,6 +80,12 @@ describe Groups::MilestonesController do
         expect(response.content_type).to eq 'application/json'
       end
     end
+
+    context 'external authorization' do
+      subject { get :index, params: { group_id: group.to_param } }
+
+      it_behaves_like 'disabled when using an external authorization service'
+    end
   end
 
   describe '#show' do

spec/controllers/groups/settings/ci_cd_controller_spec.rb

 require 'spec_helper'
 
 describe Groups::Settings::CiCdController do
+  include ExternalAuthorizationServiceHelpers
+
   let(:group) { create(:group) }
   let(:user) { create(:user) }
 
@@ -33,6 +35,19 @@ describe Groups::Settings::CiCdController do
         expect(response).to have_gitlab_http_status(404)
       end
     end
+
+    context 'external authorization' do
+      before do
+        enable_external_authorization_service_check
+        group.add_owner(user)
+      end
+
+      it 'renders show with 200 status code' do
+        get :show, params: { group_id: group }
+
+        expect(response).to have_gitlab_http_status(200)
+      end
+    end
   end
 
   describe 'PUT #reset_registration_token' do

spec/controllers/groups/variables_controller_spec.rb

 require 'spec_helper'
 
 describe Groups::VariablesController do
+  include ExternalAuthorizationServiceHelpers
+
   let(:group) { create(:group) }
   let(:user) { create(:user) }
 
@@ -34,4 +36,36 @@ describe Groups::VariablesController do
 
     include_examples 'PATCH #update updates variables'
   end
+
+  context 'with external authorization enabled' do
+    before do
+      enable_external_authorization_service_check
+    end
+
+    describe 'GET #show' do
+      let!(:variable) { create(:ci_group_variable, group: group) }
+
+      it 'is successful' do
+        get :show, params: { group_id: group }, format: :json
+
+        expect(response).to have_gitlab_http_status(200)
+      end
+    end
+
+    describe 'PATCH #update' do
+      let!(:variable) { create(:ci_group_variable, group: group) }
+      let(:owner) { group }
+
+      it 'is successful' do
+        patch :update,
+              params: {
+                group_id: group,
+                variables_attributes: [{ id: variable.id, key: 'hello' }]
+              },
+              format: :json
+
+        expect(response).to have_gitlab_http_status(200)
+      end
+    end
+  end
 end

spec/controllers/groups_controller_spec.rb

 require 'spec_helper'
 
 describe GroupsController do
+  include ExternalAuthorizationServiceHelpers
+
   let(:user) { create(:user) }
   let(:admin) { create(:admin) }
   let(:group) { create(:group, :public) }
@@ -697,4 +699,98 @@ describe GroupsController do
       end
     end
   end
+
+  describe 'external authorization' do
+    before do
+      group.add_owner(user)
+      sign_in(user)
+    end
+
+    context 'with external authorization service enabled' do
+      before do
+        enable_external_authorization_service_check
+      end
+
+      describe 'GET #show' do
+        it 'is successful' do
+          get :show, params: { id: group.to_param }
+
+          expect(response).to have_gitlab_http_status(200)
+        end
+
+        it 'does not allow other formats' do
+          get :show, params: { id: group.to_param }, format: :atom
+
+          expect(response).to have_gitlab_http_status(403)
+        end
+      end
+
+      describe 'GET #edit' do
+        it 'is successful' do
+          get :edit, params: { id: group.to_param }
+
+          expect(response).to have_gitlab_http_status(200)
+        end
+      end
+
+      describe 'GET #new' do
+        it 'is successful' do
+          get :new
+
+          expect(response).to have_gitlab_http_status(200)
+        end
+      end
+
+      describe 'GET #index' do
+        it 'is successful' do
+          get :index
+
+          # Redirects to the dashboard
+          expect(response).to have_gitlab_http_status(302)
+        end
+      end
+
+      describe 'POST #create' do
+        it 'creates a group' do
+          expect do
+            post :create, params: { group: { name: 'a name', path: 'a-name' } }
+          end.to change { Group.count }.by(1)
+        end
+      end
+
+      describe 'PUT #update' do
+        it 'updates a group' do
+          expect do
+            put :update, params: { id: group.to_param, group: { name: 'world' } }
+          end.to change { group.reload.name }
+        end
+      end
+
+      describe 'DELETE #destroy' do
+        it 'deletes the group' do
+          delete :destroy, params: { id: group.to_param }
+
+          expect(response).to have_gitlab_http_status(302)
+        end
+      end
+    end
+
+    describe 'GET #activity' do
+      subject { get :activity, params: { id: group.to_param } }
+
+      it_behaves_like 'disabled when using an external authorization service'
+    end
+
+    describe 'GET #issues' do
+      subject { get :issues, params: { id: group.to_param } }
+
+      it_behaves_like 'disabled when using an external authorization service'
+    end
+
+    describe 'GET #merge_requests' do
+      subject { get :merge_requests, params: { id: group.to_param } }
+
+      it_behaves_like 'disabled when using an external authorization service'
+    end
+  end
 end

spec/controllers/projects/boards_controller_spec.rb

@@ -98,6 +98,10 @@ describe Projects::BoardsController do
       end
     end
 
+    it_behaves_like 'unauthorized when external service denies access' do
+      subject { list_boards }
+    end
+
     def list_boards(format: :html)
       get :index, params: {
                     namespace_id: project.namespace,

spec/controllers/projects/issues_controller_spec.rb

@@ -127,6 +127,17 @@ describe Projects::IssuesController do
         expect(assigns(:issues).size).to eq(2)
       end
     end
+
+    context 'external authorization' do
+      before do
+        sign_in user
+        project.add_developer(user)
+      end
+
+      it_behaves_like 'unauthorized when external service denies access' do
+        subject { get :index, params: { namespace_id: project.namespace, project_id: project } }
+      end
+    end
   end
 
   describe 'GET #new' do

spec/controllers/projects_controller_spec.rb

 require('spec_helper')
 
 describe ProjectsController do
+  include ExternalAuthorizationServiceHelpers
   include ProjectForksHelper
 
   let(:project) { create(:project) }
@@ -430,6 +431,37 @@ describe ProjectsController do
 
       it_behaves_like 'updating a project'
     end
+
+    context 'as maintainer' do
+      before do
+        project.add_maintainer(user)
+        sign_in(user)
+      end
+
+      it_behaves_like 'unauthorized when external service denies access' do
+        subject do
+          put :update,
+              params: {
+                namespace_id: project.namespace,
+                id: project,
+                project: { description: 'Hello world' }
+              }
+          project.reload
+        end
+
+        it 'updates when the service allows access' do
+          external_service_allow_access(user, project)
+
+          expect { subject }.to change(project, :description)
+        end
+
+        it 'does not update when the service rejects access' do
+          external_service_deny_access(user, project)
+
+          expect { subject }.not_to change(project, :description)
+        end
+      end
+    end
   end
 
   describe '#transfer' do

spec/controllers/search_controller_spec.rb

 require 'spec_helper'
 
 describe SearchController do
+  include ExternalAuthorizationServiceHelpers
+
   let(:user) { create(:user) }
 
   before do
@@ -76,4 +78,41 @@ describe SearchController do
       expect(assigns[:search_objects].count).to eq(0)
     end
   end
+
+  context 'with external authorization service enabled' do
+    let(:project) { create(:project, namespace: user.namespace) }
+    let(:note) { create(:note_on_issue, project: project) }
+
+    before do
+      enable_external_authorization_service_check
+    end
+
+    describe 'GET #show' do
+      it 'renders a 403 when no project is given' do
+        get :show, params: { scope: 'notes', search: note.note }
+
+        expect(response).to have_gitlab_http_status(403)
+      end
+
+      it 'renders a 200 when a project was set' do
+        get :show, params: { project_id: project.id, scope: 'notes', search: note.note }
+
+        expect(response).to have_gitlab_http_status(200)
+      end
+    end
+
+    describe 'GET #autocomplete' do
+      it 'renders a 403 when no project is given' do
+        get :autocomplete, params: { term: 'hello' }
+
+        expect(response).to have_gitlab_http_status(403)
+      end
+
+      it 'renders a 200 when a project was set' do
+        get :autocomplete, params: { project_id: project.id, term: 'hello' }
+
+        expect(response).to have_gitlab_http_status(200)
+      end
+    end
+  end
 end

spec/controllers/users_controller_spec.rb

@@ -223,6 +223,12 @@ describe UsersController do
         end
       end
 
+      context 'external authorization' do
+        subject { get :calendar_activities, params: { username: user.username } }
+
+        it_behaves_like 'disabled when using an external authorization service'
+      end
+
       def create_push_event
         push_data = Gitlab::DataBuilder::Push.build_sample(project, public_user)
         EventCreateService.new.push(project, public_user, push_data)
@@ -286,6 +292,12 @@ describe UsersController do
         expect(JSON.parse(response.body)).to have_key('html')
       end
     end
+
+    context 'external authorization' do
+      subject { get :snippets, params: { username: user.username } }
+
+      it_behaves_like 'disabled when using an external authorization service'
+    end
   end
 
   describe 'GET #exists' do

spec/features/dashboard/group_dashboard_with_external_authorization_service_spec.rb

+require 'spec_helper'
+
+describe 'The group dashboard' do
+  include ExternalAuthorizationServiceHelpers
+
+  let(:user) { create(:user) }
+
+  before do
+    sign_in user
+  end
+
+  describe 'The top navigation' do
+    it 'has all the expected links' do
+      visit dashboard_groups_path
+
+      within('.navbar') do
+        expect(page).to have_button('Projects')
+        expect(page).to have_button('Groups')
+        expect(page).to have_link('Activity')
+        expect(page).to have_link('Milestones')
+        expect(page).to have_link('Snippets')
+      end
+    end
+
+    it 'hides some links when an external authorization service is enabled' do
+      enable_external_authorization_service_check
+      visit dashboard_groups_path
+
+      within('.navbar') do
+        expect(page).to have_button('Projects')
+        expect(page).to have_button('Groups')
+        expect(page).not_to have_link('Activity')
+        expect(page).not_to have_link('Milestones')
+        expect(page).to have_link('Snippets')
+      end
+    end
+  end
+end

spec/features/groups/group_page_with_external_authorization_service_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe 'The group page' do
+  include ExternalAuthorizationServiceHelpers
+
+  let(:user) { create(:user) }
+  let(:group) { create(:group) }
+
+  before do
+    sign_in user
+    group.add_owner(user)
+  end
+
+  def expect_all_sidebar_links
+    within('.nav-sidebar') do
+      expect(page).to have_link('Overview')
+      expect(page).to have_link('Details')
+      expect(page).to have_link('Activity')
+      expect(page).to have_link('Issues')
+      expect(page).to have_link('Merge Requests')
+      expect(page).to have_link('Members')
+    end
+  end
+
+  describe 'The sidebar' do
+    it 'has all the expected links' do
+      visit group_path(group)
+
+      expect_all_sidebar_links
+    end
+
+    it 'shows all project features when policy control is enabled' do
+      stub_application_setting(external_authorization_service_enabled: true)
+
+      visit group_path(group)
+
+      expect_all_sidebar_links
+    end
+
+    it 'hides some links when an external authorization service configured with an url' do
+      enable_external_authorization_service_check
+      visit group_path(group)
+
+      within('.nav-sidebar') do
+        expect(page).to have_link('Overview')
+        expect(page).to have_link('Details')
+        expect(page).not_to have_link('Activity')
+        expect(page).not_to have_link('Contribution Analytics')
+
+        expect(page).not_to have_link('Issues')
+        expect(page).not_to have_link('Merge Requests')
+        expect(page).to have_link('Members')
+      end
+    end
+  end
+end

spec/features/projects/classification_label_on_project_pages_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe 'Classification label on project pages' do
+  let(:project) do
+    create(:project, external_authorization_classification_label: 'authorized label')
+  end
+  let(:user) { create(:user) }
+
+  before do
+    stub_application_setting(external_authorization_service_enabled: true)
+    project.add_maintainer(user)
+    sign_in(user)
+  end
+
+  it 'shows the classification label on the project page' do
+    visit project_path(project)
+
+    expect(page).to have_content('authorized label')
+  end
+end

spec/features/projects/forks/fork_list_spec.rb

+require 'spec_helper'
+
+describe 'listing forks of a project' do
+  include ProjectForksHelper
+  include ExternalAuthorizationServiceHelpers
+
+  let(:source) { create(:project, :public, :repository) }
+  let!(:fork) { fork_project(source, nil, repository: true) }
+  let(:user) { create(:user) }
+
+  before do
+    source.add_maintainer(user)
+    sign_in(user)
+  end
+
+  it 'shows the forked project in the list with commit as description' do
+    visit project_forks_path(source)
+
+    page.within('li.project-row') do
+      expect(page).to have_content(fork.full_name)
+      expect(page).to have_css('a.commit-row-message')
+    end
+  end
+
+  it 'does not show the commit message when an external authorization service is used' do
+    enable_external_authorization_service_check
+
+    visit project_forks_path(source)
+
+    page.within('li.project-row') do
+      expect(page).to have_content(fork.full_name)
+      expect(page).not_to have_css('a.commit-row-message')
+    end
+  end
+end

spec/features/projects/issues/viewing_issues_with_external_authorization_enabled_spec.rb

+require 'spec_helper'
+
+describe 'viewing an issue with cross project references' do
+  include ExternalAuthorizationServiceHelpers
+  include Gitlab::Routing.url_helpers
+
+  let(:user) { create(:user) }
+  let(:other_project) do
+    create(:project, :public,
+          external_authorization_classification_label: 'other_label')
+  end
+  let(:other_issue) do
+    create(:issue, :closed,
+           title: 'I am in another project',
+           project: other_project)
+  end
+  let(:other_confidential_issue) do
+    create(:issue, :confidential, :closed,
+           title: 'I am in another project and confidential',
+           project: other_project)
+  end
+  let(:other_merge_request) do
+    create(:merge_request, :closed,
+           title: 'I am a merge request in another project',
+           source_project: other_project)
+  end
+  let(:description_referencing_other_issue) do
+    "Referencing: #{other_issue.to_reference(project)}, "\
+    "a confidential issue #{confidential_issue.to_reference}, "\
+    "a cross project confidential issue #{other_confidential_issue.to_reference(project)}, and "\
+    "a cross project merge request #{other_merge_request.to_reference(project)}"
+  end
+  let(:project) { create(:project) }
+  let(:issue) do
+    create(:issue,
+           project: project,
+           description: description_referencing_other_issue )
+  end
+  let(:confidential_issue) do
+    create(:issue, :confidential, :closed,
+           title: "I am in the same project and confidential",
+           project: project)
+  end
+
+  before do
+    project.add_developer(user)
+    sign_in(user)
+  end
+
+  it 'shows all information related to the cross project reference' do
+    visit project_issue_path(project, issue)
+
+    expect(page).to have_link("#{other_issue.to_reference(project)} (#{other_issue.state})")
+    expect(page).to have_xpath("//a[@title='#{other_issue.title}']")
+  end
+
+  it 'shows a link to the confidential issue in the same project' do
+    visit project_issue_path(project, issue)
+
+    expect(page).to have_link("#{confidential_issue.to_reference(project)} (#{confidential_issue.state})")
+    expect(page).to have_xpath("//a[@title='#{confidential_issue.title}']")
+  end
+
+  it 'does not show the link to a cross project confidential issue when the user does not have access' do
+    visit project_issue_path(project, issue)
+
+    expect(page).not_to have_link("#{other_confidential_issue.to_reference(project)} (#{other_confidential_issue.state})")
+    expect(page).not_to have_xpath("//a[@title='#{other_confidential_issue.title}']")
+  end
+
+  it 'shows the link to a cross project confidential issue when the user has access' do
+    other_project.add_developer(user)
+
+    visit project_issue_path(project, issue)
+
+    expect(page).to have_link("#{other_confidential_issue.to_reference(project)} (#{other_confidential_issue.state})")
+    expect(page).to have_xpath("//a[@title='#{other_confidential_issue.title}']")
+  end
+
+  context 'when an external authorization service is enabled' do
+    before do
+      enable_external_authorization_service_check
+    end
+
+    it 'only hits the external service for the project the user is viewing' do
+      expect(::Gitlab::ExternalAuthorization)
+        .to receive(:access_allowed?).with(user, 'default_label', any_args).at_least(1).and_return(true)
+      expect(::Gitlab::ExternalAuthorization)
+        .not_to receive(:access_allowed?).with(user, 'other_label', any_args)
+
+      visit project_issue_path(project, issue)
+    end
+
+    it 'shows only the link to the cross project references' do
+      visit project_issue_path(project, issue)
+
+      expect(page).to have_link("#{other_issue.to_reference(project)}")
+      expect(page).to have_link("#{other_merge_request.to_reference(project)}")
+      expect(page).not_to have_content("#{other_issue.to_reference(project)} (#{other_issue.state})")
+      expect(page).not_to have_xpath("//a[@title='#{other_issue.title}']")
+      expect(page).not_to have_content("#{other_merge_request.to_reference(project)} (#{other_merge_request.state})")
+      expect(page).not_to have_xpath("//a[@title='#{other_merge_request.title}']")
+    end
+
+    it 'does not link a cross project confidential issue if the user does not have access' do
+      visit project_issue_path(project, issue)
+
+      expect(page).not_to have_link("#{other_confidential_issue.to_reference(project)}")
+      expect(page).not_to have_xpath("//a[@title='#{other_confidential_issue.title}']")
+    end
+
+    it 'links a cross project confidential issue without exposing information when the user has access' do
+      other_project.add_developer(user)
+
+      visit project_issue_path(project, issue)
+
+      expect(page).to have_link("#{other_confidential_issue.to_reference(project)}")
+      expect(page).not_to have_xpath("//a[@title='#{other_confidential_issue.title}']")
+    end
+
+    it 'shows a link to the confidential issue in the same project' do
+      visit project_issue_path(project, issue)
+
+      expect(page).to have_link("#{confidential_issue.to_reference(project)} (#{confidential_issue.state})")
+      expect(page).to have_xpath("//a[@title='#{confidential_issue.title}']")
+    end
+  end
+end

spec/features/projects/settings/external_authorization_service_settings_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe 'Projects > Settings > External Authorization Classification Label setting' do
+  let(:user) { create(:user) }
+  let(:project) { create(:project_empty_repo) }
+
+  before do
+    project.add_maintainer(user)
+    sign_in(user)
+  end
+
+  it 'shows the field to set a classification label' do
+    stub_application_setting(external_authorization_service_enabled: true)
+
+    visit edit_project_path(project)
+
+    expect(page).to have_selector('#project_external_authorization_classification_label')
+  end
+end

spec/features/users/show_spec.rb

 require 'spec_helper'
 
 describe 'User page' do
+  include ExternalAuthorizationServiceHelpers
+
   let(:user) { create(:user) }
 
   context 'with public profile' do
@@ -86,4 +88,24 @@ describe 'User page' do
       end
     end
   end
+
+  context 'most recent activity' do
+    it 'shows the most recent activity' do
+      visit(user_path(user))
+
+      expect(page).to have_content('Most Recent Activity')
+    end
+
+    context 'when external authorization is enabled' do
+      before do
+        enable_external_authorization_service_check
+      end
+
+      it 'hides the most recent activity' do
+        visit(user_path(user))
+
+        expect(page).not_to have_content('Most Recent Activity')
+      end
+    end
+  end
 end

spec/finders/issues_finder_spec.rb

@@ -559,6 +559,13 @@ describe IssuesFinder do
         expect(issues.count).to eq 0
       end
     end
+
+    context 'external authorization' do
+      it_behaves_like 'a finder with external authorization service' do
+        let!(:subject) { create(:issue, project: project) }
+        let(:project_params) { { project_id: project.id } }
+      end
+    end
   end
 
   describe '#row_count', :request_store do

spec/finders/labels_finder_spec.rb

@@ -226,5 +226,12 @@ describe LabelsFinder do
         expect(finder.execute).to eq [project_label_1]
       end
     end
+
+    context 'external authorization' do
+      it_behaves_like 'a finder with external authorization service' do
+        let!(:subject) { create(:label, project: project) }
+        let(:project_params) { { project_id: project.id } }
+      end
+    end
   end
 end

spec/finders/merge_requests_finder_spec.rb

@@ -253,6 +253,13 @@ describe MergeRequestsFinder do
         expect(finder.row_count).to eq(1)
       end
     end
+
+    context 'external authorization' do
+      it_behaves_like 'a finder with external authorization service' do
+        let!(:subject) { create(:merge_request, source_project: project) }
+        let(:project_params) { { project_id: project.id } }
+      end
+    end
   end
 
   context 'when projects require different access levels for merge requests' do

spec/finders/snippets_finder_spec.rb

 require 'spec_helper'
 
 describe SnippetsFinder do
+  include ExternalAuthorizationServiceHelpers
   include Gitlab::Allowable
 
   describe '#initialize' do
@@ -164,4 +165,35 @@ describe SnippetsFinder do
   end
 
   it_behaves_like 'snippet visibility'
+
+  context 'external authorization' do
+    let(:user) { create(:user) }
+    let(:project) { create(:project) }
+    let!(:snippet) { create(:project_snippet, :public, project: project) }
+
+    before do
+      project.add_maintainer(user)
+    end
+
+    it_behaves_like 'a finder with external authorization service' do
+      let!(:subject) { create(:project_snippet, project: project) }
+      let(:project_params) { { project: project } }
+    end
+
+    it 'includes the result if the external service allows access' do
+      external_service_allow_access(user, project)
+
+      results = described_class.new(user, project: project).execute
+
+      expect(results).to contain_exactly(snippet)
+    end
+
+    it 'does not include any results if the external service denies access' do
+      external_service_deny_access(user, project)
+
+      results = described_class.new(user, project: project).execute
+
+      expect(results).to be_empty
+    end
+  end
 end

spec/finders/todos_finder_spec.rb

@@ -47,6 +47,13 @@ describe TodosFinder do
           end
         end
       end
+
+      context 'external authorization' do
+        it_behaves_like 'a finder with external authorization service' do
+          let!(:subject) { create(:todo, project: project, user: user) }
+          let(:project_params) { { project_id: project.id } }
+        end
+      end
     end
 
     describe '#sort' do

spec/fixtures/passphrase_x509_certificate.crt

+-----BEGIN CERTIFICATE-----
+MIIEpTCCAo0CAQEwDQYJKoZIhvcNAQEFBQAwFDESMBAGA1UEAwwJYXV0aG9yaXR5
+MB4XDTE4MDMyMzE0MDIwOFoXDTE5MDMyMzE0MDIwOFowHTEbMBkGA1UEAwwSZ2l0
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+-----END CERTIFICATE-----

spec/fixtures/passphrase_x509_certificate_pk.key

+-----BEGIN RSA PRIVATE KEY-----
+Proc-Type: 4,ENCRYPTED
+DEK-Info: AES-128-CBC,79CCB506B0FD42A6F1BAE6D72E1CB20C
+
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+-----END RSA PRIVATE KEY-----

spec/fixtures/x509_certificate.crt

+-----BEGIN CERTIFICATE-----
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+-----END CERTIFICATE-----

spec/fixtures/x509_certificate_pk.key

+-----BEGIN RSA PRIVATE KEY-----
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+-----END RSA PRIVATE KEY-----

spec/lib/gitlab/external_authorization/access_spec.rb

+require 'spec_helper'
+
+describe Gitlab::ExternalAuthorization::Access, :clean_gitlab_redis_cache do
+  subject(:access) { described_class.new(build(:user), 'dummy_label') }
+
+  describe '#loaded?' do
+    it 'is `true` when it was loaded recently' do
+      Timecop.freeze do
+        allow(access).to receive(:loaded_at).and_return(5.minutes.ago)
+
+        expect(access).to be_loaded
+      end
+    end
+
+    it 'is `false` when there is no loading time' do
+      expect(access).not_to be_loaded
+    end
+
+    it 'is `false` when there the result was loaded a long time ago' do
+      Timecop.freeze do
+        allow(access).to receive(:loaded_at).and_return(2.weeks.ago)
+
+        expect(access).not_to be_loaded
+      end
+    end
+  end
+
+  describe 'load!' do
+    let(:fake_client) { double('ExternalAuthorization::Client') }
+    let(:fake_response) do
+      double(
+        'Response',
+        'successful?' => true,
+        'valid?' => true,
+        'reason' => nil
+      )
+    end
+
+    before do
+      allow(access).to receive(:load_from_cache)
+      allow(fake_client).to receive(:request_access).and_return(fake_response)
+      allow(Gitlab::ExternalAuthorization::Client).to receive(:new) { fake_client }
+    end
+
+    context 'when loading from the webservice' do
+      it 'loads from the webservice it the cache was empty' do
+        expect(access).to receive(:load_from_cache)
+        expect(access).to receive(:load_from_service).and_call_original
+
+        access.load!
+
+        expect(access).to be_loaded
+      end
+
+      it 'assigns the accessibility, reason and loaded_at' do
+        allow(fake_response).to receive(:successful?).and_return(false)
+        allow(fake_response).to receive(:reason).and_return('Inaccessible label')
+
+        access.load!
+
+        expect(access.reason).to eq('Inaccessible label')
+        expect(access).not_to have_access
+        expect(access.loaded_at).not_to be_nil
+      end
+
+      it 'returns itself' do
+        expect(access.load!).to eq(access)
+      end
+
+      it 'stores the result in redis' do
+        Timecop.freeze do
+          fake_cache = double
+          expect(fake_cache).to receive(:store).with(true, nil, Time.now)
+          expect(access).to receive(:cache).and_return(fake_cache)
+
+          access.load!
+        end
+      end
+
+      context 'when the request fails' do
+        before do
+          allow(fake_client).to receive(:request_access) do
+            raise ::Gitlab::ExternalAuthorization::RequestFailed.new('Service unavailable')
+          end
+        end
+
+        it 'is loaded' do
+          access.load!
+
+          expect(access).to be_loaded
+        end
+
+        it 'assigns the correct accessibility, reason and loaded_at' do
+          access.load!
+
+          expect(access.reason).to eq('Service unavailable')
+          expect(access).not_to have_access
+          expect(access.loaded_at).not_to be_nil
+        end
+
+        it 'does not store the result in redis' do
+          fake_cache = double
+          expect(fake_cache).not_to receive(:store)
+          allow(access).to receive(:cache).and_return(fake_cache)
+
+          access.load!
+        end
+      end
+    end
+
+    context 'When loading from cache' do
+      let(:fake_cache) { double('ExternalAuthorization::Cache') }
+
+      before do
+        allow(access).to receive(:cache).and_return(fake_cache)
+      end
+
+      it 'does not load from the webservice' do
+        Timecop.freeze do
+          expect(fake_cache).to receive(:load).and_return([true, nil, Time.now])
+
+          expect(access).to receive(:load_from_cache).and_call_original
+          expect(access).not_to receive(:load_from_service)
+
+          access.load!
+        end
+      end
+
+      it 'loads from the webservice when the cached result was too old' do
+        Timecop.freeze do
+          expect(fake_cache).to receive(:load).and_return([true, nil, 2.days.ago])
+
+          expect(access).to receive(:load_from_cache).and_call_original
+          expect(access).to receive(:load_from_service).and_call_original
+          allow(fake_cache).to receive(:store)
+
+          access.load!
+        end
+      end
+    end
+  end
+end

spec/lib/gitlab/external_authorization/cache_spec.rb

+require 'spec_helper'
+
+describe Gitlab::ExternalAuthorization::Cache, :clean_gitlab_redis_cache do
+  let(:user) { build_stubbed(:user) }
+  let(:cache_key) { "external_authorization:user-#{user.id}:label-dummy_label" }
+
+  subject(:cache) { described_class.new(user, 'dummy_label') }
+
+  def read_from_redis(key)
+    Gitlab::Redis::Cache.with do |redis|
+      redis.hget(cache_key, key)
+    end
+  end
+
+  def set_in_redis(key, value)
+    Gitlab::Redis::Cache.with do |redis|
+      redis.hmset(cache_key, key, value)
+    end
+  end
+
+  describe '#load' do
+    it 'reads stored info from redis' do
+      Timecop.freeze do
+        set_in_redis(:access, false)
+        set_in_redis(:reason, 'Access denied for now')
+        set_in_redis(:refreshed_at, Time.now)
+
+        access, reason, refreshed_at = cache.load
+
+        expect(access).to eq(false)
+        expect(reason).to eq('Access denied for now')
+        expect(refreshed_at).to be_within(1.second).of(Time.now)
+      end
+    end
+  end
+
+  describe '#store' do
+    it 'sets the values in redis' do
+      Timecop.freeze do
+        cache.store(true, 'the reason', Time.now)
+
+        expect(read_from_redis(:access)).to eq('true')
+        expect(read_from_redis(:reason)).to eq('the reason')
+        expect(read_from_redis(:refreshed_at)).to eq(Time.now.to_s)
+      end
+    end
+  end
+end

spec/lib/gitlab/external_authorization/client_spec.rb

+require 'spec_helper'
+
+describe Gitlab::ExternalAuthorization::Client do
+  let(:user) { build(:user, email: 'dummy_user@example.com') }
+  let(:dummy_url) { 'https://dummy.net/' }
+  subject(:client) { described_class.new(user, 'dummy_label') }
+
+  before do
+    stub_application_setting(external_authorization_service_url: dummy_url)
+  end
+
+  describe '#request_access' do
+    it 'performs requests to the configured endpoint' do
+      expect(Excon).to receive(:post).with(dummy_url, any_args)
+
+      client.request_access
+    end
+
+    it 'adds the correct params for the user to the body of the request' do
+      expected_body = {
+        user_identifier: 'dummy_user@example.com',
+        project_classification_label: 'dummy_label'
+      }.to_json
+      expect(Excon).to receive(:post)
+                         .with(dummy_url, hash_including(body: expected_body))
+
+      client.request_access
+    end
+
+    it 'respects the the timeout' do
+      stub_application_setting(
+        external_authorization_service_timeout: 3
+      )
+
+      expect(Excon).to receive(:post).with(dummy_url,
+                                           hash_including(
+                                             connect_timeout: 3,
+                                             read_timeout: 3,
+                                             write_timeout: 3
+                                           ))
+
+      client.request_access
+    end
+
+    it 'adds the mutual tls params when they are present' do
+      stub_application_setting(
+        external_auth_client_cert: 'the certificate data',
+        external_auth_client_key: 'the key data',
+        external_auth_client_key_pass: 'open sesame'
+      )
+      expected_params = {
+        client_cert_data: 'the certificate data',
+        client_key_data: 'the key data',
+        client_key_pass: 'open sesame'
+      }
+
+      expect(Excon).to receive(:post).with(dummy_url, hash_including(expected_params))
+
+      client.request_access
+    end
+
+    it 'returns an expected response' do
+      expect(Excon).to receive(:post)
+
+      expect(client.request_access)
+        .to be_kind_of(::Gitlab::ExternalAuthorization::Response)
+    end
+
+    it 'wraps exceptions if the request fails' do
+      expect(Excon).to receive(:post) { raise Excon::Error.new('the request broke') }
+
+      expect { client.request_access }
+        .to raise_error(::Gitlab::ExternalAuthorization::RequestFailed)
+    end
+
+    describe 'for ldap users' do
+      let(:user) do
+        create(:omniauth_user,
+               email: 'dummy_user@example.com',
+               extern_uid: 'external id',
+               provider: 'ldapprovider')
+      end
+
+      it 'includes the ldap dn for ldap users' do
+        expected_body = {
+          user_identifier: 'dummy_user@example.com',
+          project_classification_label: 'dummy_label',
+          user_ldap_dn: 'external id'
+        }.to_json
+        expect(Excon).to receive(:post)
+                           .with(dummy_url, hash_including(body: expected_body))
+
+        client.request_access
+      end
+    end
+  end
+end

spec/lib/gitlab/external_authorization/logger_spec.rb

+require 'spec_helper'
+
+describe Gitlab::ExternalAuthorization::Logger do
+  let(:request_time) { Time.parse('2018-03-26 20:22:15') }
+
+  def fake_access(has_access, user, load_type = :request)
+    access = double('access')
+    allow(access).to receive_messages(user: user,
+                                      has_access?: has_access,
+                                      loaded_at: request_time,
+                                      label: 'dummy_label',
+                                      load_type: load_type)
+
+    access
+  end
+
+  describe '.log_access' do
+    it 'logs a nice message for an access request' do
+      expected_message = "GRANTED admin@example.com access to 'dummy_label' (the/project/path)"
+      fake_access = fake_access(true, build(:user, email: 'admin@example.com'))
+
+      expect(described_class).to receive(:info).with(expected_message)
+
+      described_class.log_access(fake_access, 'the/project/path')
+    end
+
+    it 'does not trip without a project path' do
+      expected_message = "DENIED admin@example.com access to 'dummy_label'"
+      fake_access = fake_access(false, build(:user, email: 'admin@example.com'))
+
+      expect(described_class).to receive(:info).with(expected_message)
+
+      described_class.log_access(fake_access, nil)
+    end
+
+    it 'adds the load time for cached accesses' do
+      expected_message = "DENIED admin@example.com access to 'dummy_label' - cache #{request_time}"
+      fake_access = fake_access(false, build(:user, email: 'admin@example.com'), :cache)
+
+      expect(described_class).to receive(:info).with(expected_message)
+
+      described_class.log_access(fake_access, nil)
+    end
+  end
+end

spec/lib/gitlab/external_authorization/response_spec.rb

+require 'spec_helper'
+
+describe Gitlab::ExternalAuthorization::Response do
+  let(:excon_response) { double }
+  subject(:response) { described_class.new(excon_response) }
+
+  describe '#valid?' do
+    it 'is valid for 200, 401, and 403 responses' do
+      [200, 401, 403].each do |status|
+        allow(excon_response).to receive(:status).and_return(status)
+
+        expect(response).to be_valid
+      end
+    end
+
+    it "is invalid for other statuses" do
+      expect(excon_response).to receive(:status).and_return(500)
+
+      expect(response).not_to be_valid
+    end
+  end
+
+  describe '#reason' do
+    it 'returns a reason if it was included in the response body' do
+      expect(excon_response).to receive(:body).and_return({ reason: 'Not authorized' }.to_json)
+
+      expect(response.reason).to eq('Not authorized')
+    end
+
+    it 'returns nil when there was no body' do
+      expect(excon_response).to receive(:body).and_return('')
+
+      expect(response.reason).to eq(nil)
+    end
+  end
+
+  describe '#successful?' do
+    it 'is `true` if the status is 200' do
+      allow(excon_response).to receive(:status).and_return(200)
+
+      expect(response).to be_successful
+    end
+
+    it 'is `false` if the status is 401 or 403' do
+      [401, 403].each do |status|
+        allow(excon_response).to receive(:status).and_return(status)
+
+        expect(response).not_to be_successful
+      end
+    end
+  end
+end

spec/lib/gitlab/external_authorization_spec.rb

+require 'spec_helper'
+
+describe Gitlab::ExternalAuthorization, :request_store do
+  include ExternalAuthorizationServiceHelpers
+
+  let(:user) { build(:user) }
+  let(:label) { 'dummy_label' }
+
+  describe '#access_allowed?' do
+    it 'is always true when the feature is disabled' do
+      # Not using `stub_application_setting` because the method is prepended in
+      # `EE::ApplicationSetting` which breaks when using `any_instance`
+      # https://gitlab.com/gitlab-org/gitlab-ce/issues/33587
+      expect(::Gitlab::CurrentSettings.current_application_settings)
+        .to receive(:external_authorization_service_enabled) { false }
+
+      expect(described_class).not_to receive(:access_for_user_to_label)
+
+      expect(described_class.access_allowed?(user, label)).to be_truthy
+    end
+  end
+
+  describe '#rejection_reason' do
+    it 'is always nil when the feature is disabled' do
+      expect(::Gitlab::CurrentSettings.current_application_settings)
+        .to receive(:external_authorization_service_enabled) { false }
+
+      expect(described_class).not_to receive(:access_for_user_to_label)
+
+      expect(described_class.rejection_reason(user, label)).to be_nil
+    end
+  end
+
+  describe '#access_for_user_to_label' do
+    it 'only loads the access once per request' do
+      enable_external_authorization_service_check
+
+      expect(::Gitlab::ExternalAuthorization::Access)
+        .to receive(:new).with(user, label).once.and_call_original
+
+      2.times { described_class.access_for_user_to_label(user, label, nil) }
+    end
+
+    it 'logs the access request once per request' do
+      expect(::Gitlab::ExternalAuthorization::Logger)
+        .to receive(:log_access)
+              .with(an_instance_of(::Gitlab::ExternalAuthorization::Access),
+                    'the/project/path')
+              .once
+
+      2.times { described_class.access_for_user_to_label(user, label, 'the/project/path') }
+    end
+  end
+end

spec/models/application_setting_spec.rb

@@ -3,7 +3,7 @@
 require 'spec_helper'
 
 describe ApplicationSetting do
-  let(:setting) { described_class.create_from_defaults }
+  subject(:setting) { described_class.create_from_defaults }
 
   it { include(CacheableAttributes) }
   it { include(ApplicationSettingImplementation) }
@@ -284,6 +284,52 @@ describe ApplicationSetting do
         expect(subject).to be_valid
       end
     end
+
+    describe 'when external authorization service is enabled' do
+      before do
+        setting.external_authorization_service_enabled = true
+      end
+
+      it { is_expected.not_to allow_value('not a URL').for(:external_authorization_service_url) }
+      it { is_expected.to allow_value('https://example.com').for(:external_authorization_service_url) }
+      it { is_expected.to allow_value('').for(:external_authorization_service_url) }
+      it { is_expected.not_to allow_value(nil).for(:external_authorization_service_default_label) }
+      it { is_expected.not_to allow_value(11).for(:external_authorization_service_timeout) }
+      it { is_expected.not_to allow_value(0).for(:external_authorization_service_timeout) }
+      it { is_expected.not_to allow_value('not a certificate').for(:external_auth_client_cert) }
+      it { is_expected.to allow_value('').for(:external_auth_client_cert) }
+      it { is_expected.to allow_value('').for(:external_auth_client_key) }
+
+      context 'when setting a valid client certificate for external authorization' do
+        let(:certificate_data) { File.read('spec/fixtures/passphrase_x509_certificate.crt') }
+
+        before do
+          setting.external_auth_client_cert = certificate_data
+        end
+
+        it 'requires a valid client key when a certificate is set' do
+          expect(setting).not_to allow_value('fefefe').for(:external_auth_client_key)
+        end
+
+        it 'requires a matching certificate' do
+          other_private_key = File.read('spec/fixtures/x509_certificate_pk.key')
+
+          expect(setting).not_to allow_value(other_private_key).for(:external_auth_client_key)
+        end
+
+        it 'the credentials are valid when the private key can be read and matches the certificate' do
+          tls_attributes = [:external_auth_client_key_pass,
+                            :external_auth_client_key,
+                            :external_auth_client_cert]
+          setting.external_auth_client_key = File.read('spec/fixtures/passphrase_x509_certificate_pk.key')
+          setting.external_auth_client_key_pass = '5iveL!fe'
+
+          setting.validate
+
+          expect(setting.errors).not_to include(*tls_attributes)
+        end
+      end
+    end
   end
 
   context 'restrict creating duplicates' do

spec/models/concerns/protected_ref_access_spec.rb

@@ -3,6 +3,8 @@
 require 'spec_helper'
 
 describe ProtectedRefAccess do
+  include ExternalAuthorizationServiceHelpers
+
   subject(:protected_ref_access) do
     create(:protected_branch, :maintainers_can_push).push_access_levels.first
   end
@@ -29,5 +31,15 @@ describe ProtectedRefAccess do
 
       expect(protected_ref_access.check_access(developer)).to be_falsy
     end
+
+    context 'external authorization' do
+      it 'is false if external authorization denies access' do
+        maintainer = create(:user)
+        project.add_maintainer(maintainer)
+        external_service_deny_access(maintainer, project)
+
+        expect(protected_ref_access.check_access(maintainer)).to be_falsey
+      end
+    end
   end
 end

spec/models/issue_spec.rb

@@ -3,6 +3,8 @@
 require 'spec_helper'
 
 describe Issue do
+  include ExternalAuthorizationServiceHelpers
+
   describe "Associations" do
     it { is_expected.to belong_to(:milestone) }
     it { is_expected.to have_many(:assignees) }
@@ -779,4 +781,47 @@ describe Issue do
   it_behaves_like 'throttled touch' do
     subject { create(:issue, updated_at: 1.hour.ago) }
   end
+
+  context 'when an external authentication service' do
+    before do
+      enable_external_authorization_service_check
+    end
+
+    describe '#visible_to_user?' do
+      it 'is `false` when an external authorization service is enabled' do
+        issue = build(:issue, project: build(:project, :public))
+
+        expect(issue).not_to be_visible_to_user
+      end
+
+      it 'checks the external service to determine if an issue is readable by a user' do
+        project = build(:project, :public,
+                        external_authorization_classification_label: 'a-label')
+        issue = build(:issue, project: project)
+        user = build(:user)
+
+        expect(::Gitlab::ExternalAuthorization).to receive(:access_allowed?).with(user, 'a-label') { false }
+        expect(issue.visible_to_user?(user)).to be_falsy
+      end
+
+      it 'does not check the external service if a user does not have access to the project' do
+        project = build(:project, :private,
+                        external_authorization_classification_label: 'a-label')
+        issue = build(:issue, project: project)
+        user = build(:user)
+
+        expect(::Gitlab::ExternalAuthorization).not_to receive(:access_allowed?)
+        expect(issue.visible_to_user?(user)).to be_falsy
+      end
+
+      it 'does not check the external webservice for admins' do
+        issue = build(:issue)
+        user = build(:admin)
+
+        expect(::Gitlab::ExternalAuthorization).not_to receive(:access_allowed?)
+
+        issue.visible_to_user?(user)
+      end
+    end
+  end
 end

spec/models/project_spec.rb

@@ -5,6 +5,7 @@ require 'spec_helper'
 describe Project do
   include ProjectForksHelper
   include GitHelpers
+  include ExternalAuthorizationServiceHelpers
 
   it_behaves_like 'having unique enum values'
 
@@ -4417,6 +4418,25 @@ describe Project do
     end
   end
 
+  describe '#external_authorization_classification_label' do
+    it 'falls back to the default when none is configured' do
+      enable_external_authorization_service_check
+
+      expect(build(:project).external_authorization_classification_label)
+        .to eq('default_label')
+    end
+
+    it 'returns the classification label if it was configured on the project' do
+      enable_external_authorization_service_check
+
+      project = build(:project,
+                      external_authorization_classification_label: 'hello')
+
+      expect(project.external_authorization_classification_label)
+        .to eq('hello')
+    end
+  end
+
   describe "#pages_https_only?" do
     subject { build(:project) }
 

spec/policies/base_policy_spec.rb

 require 'spec_helper'
 
 describe BasePolicy do
+  include ExternalAuthorizationServiceHelpers
+
   describe '.class_for' do
     it 'detects policy class based on the subject ancestors' do
       expect(DeclarativePolicy.class_for(GenericCommitStatus.new)).to eq(CommitStatusPolicy)
@@ -16,4 +18,25 @@ describe BasePolicy do
       expect(DeclarativePolicy.class_for(:global)).to eq(GlobalPolicy)
     end
   end
+
+  describe 'read cross project' do
+    let(:current_user) { create(:user) }
+    let(:user) { create(:user) }
+
+    subject { described_class.new(current_user, [user]) }
+
+    it { is_expected.to be_allowed(:read_cross_project) }
+
+    context 'when an external authorization service is enabled' do
+      before do
+        enable_external_authorization_service_check
+      end
+
+      it { is_expected.not_to be_allowed(:read_cross_project) }
+
+      it 'allows admins' do
+        expect(described_class.new(build(:admin), nil)).to be_allowed(:read_cross_project)
+      end
+    end
+  end
 end

spec/policies/issue_policy_spec.rb

 require 'spec_helper'
 
 describe IssuePolicy do
+  include ExternalAuthorizationServiceHelpers
+
   let(:guest) { create(:user) }
   let(:author) { create(:user) }
   let(:assignee) { create(:user) }
@@ -204,4 +206,21 @@ describe IssuePolicy do
       end
     end
   end
+
+  context 'with external authorization enabled' do
+    let(:user) { create(:user) }
+    let(:project) { create(:project, :public) }
+    let(:issue) { create(:issue, project: project) }
+    let(:policies) { described_class.new(user, issue) }
+
+    before do
+      enable_external_authorization_service_check
+    end
+
+    it 'can read the issue iid without accessing the external service' do
+      expect(::Gitlab::ExternalAuthorization).not_to receive(:access_allowed?)
+
+      expect(policies).to be_allowed(:read_issue_iid)
+    end
+  end
 end

spec/policies/merge_request_policy_spec.rb

 require 'spec_helper'
 
 describe MergeRequestPolicy do
+  include ExternalAuthorizationServiceHelpers
+
   let(:guest) { create(:user) }
   let(:author) { create(:user) }
   let(:developer) { create(:user) }
@@ -47,4 +49,21 @@ describe MergeRequestPolicy do
       expect(permissions(guest, merge_request_locked)).to be_disallowed(:reopen_merge_request)
     end
   end
+
+  context 'with external authorization enabled' do
+    let(:user) { create(:user) }
+    let(:project) { create(:project, :public) }
+    let(:merge_request) { create(:merge_request, source_project: project) }
+    let(:policies) { described_class.new(user, merge_request) }
+
+    before do
+      enable_external_authorization_service_check
+    end
+
+    it 'can read the issue iid without accessing the external service' do
+      expect(::Gitlab::ExternalAuthorization).not_to receive(:access_allowed?)
+
+      expect(policies).to be_allowed(:read_merge_request_iid)
+    end
+  end
 end

spec/policies/project_policy_spec.rb

 require 'spec_helper'
 
 describe ProjectPolicy do
+  include ExternalAuthorizationServiceHelpers
   include_context 'ProjectPolicy context'
   set(:guest) { create(:user) }
   set(:reporter) { create(:user) }
@@ -292,4 +293,56 @@ describe ProjectPolicy do
              projects: [clusterable])
     end
   end
+
+  context 'reading a project' do
+    it 'allows access when a user has read access to the repo' do
+      expect(described_class.new(owner, project)).to be_allowed(:read_project)
+      expect(described_class.new(developer, project)).to be_allowed(:read_project)
+      expect(described_class.new(admin, project)).to be_allowed(:read_project)
+    end
+
+    it 'never checks the external service' do
+      expect(::Gitlab::ExternalAuthorization).not_to receive(:access_allowed?)
+
+      expect(described_class.new(owner, project)).to be_allowed(:read_project)
+    end
+
+    context 'with an external authorization service' do
+      before do
+        enable_external_authorization_service_check
+      end
+
+      it 'allows access when the external service allows it' do
+        external_service_allow_access(owner, project)
+        external_service_allow_access(developer, project)
+
+        expect(described_class.new(owner, project)).to be_allowed(:read_project)
+        expect(described_class.new(developer, project)).to be_allowed(:read_project)
+      end
+
+      it 'does not check the external service for admins and allows access' do
+        expect(::Gitlab::ExternalAuthorization).not_to receive(:access_allowed?)
+
+        expect(described_class.new(admin, project)).to be_allowed(:read_project)
+      end
+
+      it 'prevents all but seeing a public project in a list when access is denied' do
+        [developer, owner, build(:user), nil].each do |user|
+          external_service_deny_access(user, project)
+          policy = described_class.new(user, project)
+
+          expect(policy).not_to be_allowed(:read_project)
+          expect(policy).not_to be_allowed(:owner_access)
+          expect(policy).not_to be_allowed(:change_namespace)
+        end
+      end
+
+      it 'passes the full path to external authorization for logging purposes' do
+        expect(::Gitlab::ExternalAuthorization)
+          .to receive(:access_allowed?).with(owner, 'default_label', project.full_path).and_call_original
+
+        described_class.new(owner, project).allowed?(:read_project)
+      end
+    end
+  end
 end

spec/requests/api/projects_spec.rb

@@ -46,6 +46,8 @@ shared_examples 'languages and percentages JSON response' do
 end
 
 describe API::Projects do
+  include ExternalAuthorizationServiceHelpers
+
   let(:user) { create(:user) }
   let(:user2) { create(:user) }
   let(:user3) { create(:user) }
@@ -1386,6 +1388,39 @@ describe API::Projects do
         end
       end
     end
+
+    context 'with external authorization' do
+      let(:project) do
+        create(:project,
+               namespace: user.namespace,
+               external_authorization_classification_label: 'the-label')
+      end
+
+      context 'when the user has access to the project' do
+        before do
+          external_service_allow_access(user, project)
+        end
+
+        it 'includes the label in the response' do
+          get api("/projects/#{project.id}", user)
+
+          expect(response).to have_gitlab_http_status(200)
+          expect(json_response['external_authorization_classification_label']).to eq('the-label')
+        end
+      end
+
+      context 'when the external service denies access' do
+        before do
+          external_service_deny_access(user, project)
+        end
+
+        it 'returns a 404' do
+          get api("/projects/#{project.id}", user)
+
+          expect(response).to have_gitlab_http_status(404)
+        end
+      end
+    end
   end
 
   describe 'GET /projects/:id/users' do
@@ -1956,6 +1991,20 @@ describe API::Projects do
         expect(response).to have_gitlab_http_status(403)
       end
     end
+
+    context 'when updating external classification' do
+      before do
+        enable_external_authorization_service_check
+      end
+
+      it 'updates the classification label' do
+        put(api("/projects/#{project.id}", user), params: { external_authorization_classification_label: 'new label' })
+
+        expect(response).to have_gitlab_http_status(200)
+
+        expect(project.reload.external_authorization_classification_label).to eq('new label')
+      end
+    end
   end
 
   describe 'POST /projects/:id/archive' do

spec/requests/api/settings_spec.rb

@@ -115,6 +115,39 @@ describe API::Settings, 'Settings' do
       expect(json_response['performance_bar_allowed_group_id']).to be_nil
     end
 
+    context 'external policy classification settings' do
+      let(:settings) do
+        {
+          external_authorization_service_enabled: true,
+          external_authorization_service_url: 'https://custom.service/',
+          external_authorization_service_default_label: 'default',
+          external_authorization_service_timeout: 9.99,
+          external_auth_client_cert: File.read('spec/fixtures/passphrase_x509_certificate.crt'),
+          external_auth_client_key: File.read('spec/fixtures/passphrase_x509_certificate_pk.key'),
+          external_auth_client_key_pass: "5iveL!fe"
+        }
+      end
+      let(:attribute_names) { settings.keys.map(&:to_s) }
+
+      it 'includes the attributes in the API' do
+        get api("/application/settings", admin)
+
+        expect(response).to have_gitlab_http_status(200)
+        attribute_names.each do |attribute|
+          expect(json_response.keys).to include(attribute)
+        end
+      end
+
+      it 'allows updating the settings' do
+        put api("/application/settings", admin), params: settings
+
+        expect(response).to have_gitlab_http_status(200)
+        settings.each do |attribute, value|
+          expect(ApplicationSetting.current.public_send(attribute)).to eq(value)
+        end
+      end
+    end
+
     context "missing plantuml_url value when plantuml_enabled is true" do
       it "returns a blank parameter error message" do
         put api("/application/settings", admin), params: { plantuml_enabled: true }

spec/serializers/group_child_entity_spec.rb

 require 'spec_helper'
 
 describe GroupChildEntity do
+  include ExternalAuthorizationServiceHelpers
   include Gitlab::Routing.url_helpers
 
   let(:user) { create(:user) }
@@ -109,4 +110,22 @@ describe GroupChildEntity do
 
     it_behaves_like 'group child json'
   end
+
+  describe 'for a project with external authorization enabled' do
+    let(:object) do
+      create(:project, :with_avatar,
+             description: 'Awesomeness')
+    end
+
+    before do
+      enable_external_authorization_service_check
+      object.add_maintainer(user)
+    end
+
+    it 'does not hit the external authorization service' do
+      expect(::Gitlab::ExternalAuthorization).not_to receive(:access_allowed?)
+
+      expect(json[:can_edit]).to eq(false)
+    end
+  end
 end

spec/services/application_settings/update_service_spec.rb

 require 'spec_helper'
 
 describe ApplicationSettings::UpdateService do
+  include ExternalAuthorizationServiceHelpers
+
   let(:application_settings) { create(:application_setting) }
   let(:admin) { create(:user, :admin) }
   let(:params) { {} }
@@ -143,4 +145,37 @@ describe ApplicationSettings::UpdateService do
       end
     end
   end
+
+  context 'when external authorization is enabled' do
+    before do
+      enable_external_authorization_service_check
+    end
+
+    it 'does not save the settings with an error if the service denies access' do
+      expect(::Gitlab::ExternalAuthorization)
+        .to receive(:access_allowed?).with(admin, 'new-label') { false }
+
+      described_class.new(application_settings, admin, { external_authorization_service_default_label: 'new-label' }).execute
+
+      expect(application_settings.errors[:external_authorization_service_default_label]).to be_present
+    end
+
+    it 'saves the setting when the user has access to the label' do
+      expect(::Gitlab::ExternalAuthorization)
+        .to receive(:access_allowed?).with(admin, 'new-label') { true }
+
+      described_class.new(application_settings, admin, { external_authorization_service_default_label: 'new-label' }).execute
+
+      # Read the attribute directly to avoid the stub from
+      # `enable_external_authorization_service_check`
+      expect(application_settings[:external_authorization_service_default_label]).to eq('new-label')
+    end
+
+    it 'does not validate the label if it was not passed' do
+      expect(::Gitlab::ExternalAuthorization)
+        .not_to receive(:access_allowed?)
+
+      described_class.new(application_settings, admin, { home_page_url: 'http://foo.bar' }).execute
+    end
+  end
 end

spec/services/notification_service_spec.rb

@@ -2,6 +2,7 @@ require 'spec_helper'
 
 describe NotificationService, :mailer do
   include EmailSpec::Matchers
+  include ExternalAuthorizationServiceHelpers
   include NotificationHelpers
 
   let(:notification) { described_class.new }
@@ -2217,6 +2218,46 @@ describe NotificationService, :mailer do
     end
   end
 
+  context 'with external authorization service' do
+    let(:issue) { create(:issue) }
+    let(:project) { issue.project }
+    let(:note) { create(:note, noteable: issue, project: project) }
+    let(:member) { create(:user) }
+
+    subject { NotificationService.new }
+
+    before do
+      project.add_maintainer(member)
+      member.global_notification_setting.update!(level: :watch)
+    end
+
+    it 'sends email when the service is not enabled' do
+      expect(Notify).to receive(:new_issue_email).at_least(:once).with(member.id, issue.id, nil).and_call_original
+
+      subject.new_issue(issue, member)
+    end
+
+    context 'when the service is enabled' do
+      before do
+        enable_external_authorization_service_check
+      end
+
+      it 'does not send an email' do
+        expect(Notify).not_to receive(:new_issue_email)
+
+        subject.new_issue(issue, member)
+      end
+
+      it 'still delivers email to admins' do
+        member.update!(admin: true)
+
+        expect(Notify).to receive(:new_issue_email).at_least(:once).with(member.id, issue.id, nil).and_call_original
+
+        subject.new_issue(issue, member)
+      end
+    end
+  end
+
   def build_team(project)
     @u_watcher               = create_global_setting_for(create(:user), :watch)
     @u_participating         = create_global_setting_for(create(:user), :participating)

spec/services/projects/create_service_spec.rb

 require 'spec_helper'
 
 describe Projects::CreateService, '#execute' do
+  include ExternalAuthorizationServiceHelpers
   include GitHelpers
 
   let(:gitlab_shell) { Gitlab::Shell.new }
@@ -344,6 +345,42 @@ describe Projects::CreateService, '#execute' do
     expect(rugged.config['gitlab.fullpath']).to eq project.full_path
   end
 
+  context 'with external authorization enabled' do
+    before do
+      enable_external_authorization_service_check
+    end
+
+    it 'does not save the project with an error if the service denies access' do
+      expect(::Gitlab::ExternalAuthorization)
+        .to receive(:access_allowed?).with(user, 'new-label', any_args) { false }
+
+      project = create_project(user, opts.merge({ external_authorization_classification_label: 'new-label' }))
+
+      expect(project.errors[:external_authorization_classification_label]).to be_present
+      expect(project).not_to be_persisted
+    end
+
+    it 'saves the project when the user has access to the label' do
+      expect(::Gitlab::ExternalAuthorization)
+        .to receive(:access_allowed?).with(user, 'new-label', any_args) { true }
+
+      project = create_project(user, opts.merge({ external_authorization_classification_label: 'new-label' }))
+
+      expect(project).to be_persisted
+      expect(project.external_authorization_classification_label).to eq('new-label')
+    end
+
+    it 'does not save the project when the user has no access to the default label and no label is provided' do
+      expect(::Gitlab::ExternalAuthorization)
+        .to receive(:access_allowed?).with(user, 'default_label', any_args) { false }
+
+      project = create_project(user, opts)
+
+      expect(project.errors[:external_authorization_classification_label]).to be_present
+      expect(project).not_to be_persisted
+    end
+  end
+
   def create_project(user, opts)
     Projects::CreateService.new(user, opts).execute
   end

spec/services/projects/update_service_spec.rb

@@ -362,6 +362,46 @@ describe Projects::UpdateService, '#execute' do
         call_service
       end
     end
+
+    context 'with external authorization enabled' do
+      before do
+        enable_external_authorization_service_check
+      end
+
+      it 'does not save the project with an error if the service denies access' do
+        expect(::Gitlab::ExternalAuthorization)
+          .to receive(:access_allowed?).with(user, 'new-label') { false }
+
+        result = update_project(project, user, { external_authorization_classification_label: 'new-label' })
+
+        expect(result[:message]).to be_present
+        expect(result[:status]).to eq(:error)
+      end
+
+      it 'saves the new label if the service allows access' do
+        expect(::Gitlab::ExternalAuthorization)
+          .to receive(:access_allowed?).with(user, 'new-label') { true }
+
+        result = update_project(project, user, { external_authorization_classification_label: 'new-label' })
+
+        expect(result[:status]).to eq(:success)
+        expect(project.reload.external_authorization_classification_label).to eq('new-label')
+      end
+
+      it 'checks the default label when the classification label was cleared' do
+        expect(::Gitlab::ExternalAuthorization)
+          .to receive(:access_allowed?).with(user, 'default_label') { true }
+
+        update_project(project, user, { external_authorization_classification_label: '' })
+      end
+
+      it 'does not check the label when it does not change' do
+        expect(::Gitlab::ExternalAuthorization)
+          .not_to receive(:access_allowed?)
+
+        update_project(project, user, { name: 'New name' })
+      end
+    end
   end
 
   describe '#run_auto_devops_pipeline?' do

spec/support/external_authorization_service_helpers.rb

+module ExternalAuthorizationServiceHelpers
+  def enable_external_authorization_service_check
+    stub_application_setting(external_authorization_service_enabled: true)
+
+    stub_application_setting(external_authorization_service_url: 'https://authorize.me')
+    stub_application_setting(external_authorization_service_default_label: 'default_label')
+    stub_request(:post, "https://authorize.me").to_return(status: 200)
+  end
+
+  def external_service_set_access(allowed, user, project)
+    enable_external_authorization_service_check
+    classification_label = ::Gitlab::CurrentSettings.current_application_settings
+                             .external_authorization_service_default_label
+
+    # Reload the project so cached licensed features are reloaded
+    if project
+      classification_label = Project.find(project.id).external_authorization_classification_label
+    end
+
+    allow(::Gitlab::ExternalAuthorization)
+      .to receive(:access_allowed?)
+            .with(user, classification_label, any_args)
+            .and_return(allowed)
+  end
+
+  def external_service_allow_access(user, project = nil)
+    external_service_set_access(true, user, project)
+  end
+
+  def external_service_deny_access(user, project = nil)
+    external_service_set_access(false, user, project)
+  end
+end

spec/support/shared_examples/controllers/external_authorization_service_shared_examples.rb

+require 'spec_helper'
+
+shared_examples 'disabled when using an external authorization service' do
+  include ExternalAuthorizationServiceHelpers
+
+  it 'works when the feature is not enabled' do
+    subject
+
+    expect(response).to be_success
+  end
+
+  it 'renders a 404 with a message when the feature is enabled' do
+    enable_external_authorization_service_check
+
+    subject
+
+    expect(response).to have_gitlab_http_status(403)
+  end
+end
+
+shared_examples 'unauthorized when external service denies access' do
+  include ExternalAuthorizationServiceHelpers
+
+  it 'allows access when the authorization service allows it' do
+    external_service_allow_access(user, project)
+
+    subject
+
+    # Account for redirects after updates
+    expect(response.status).to be_between(200, 302)
+  end
+
+  it 'allows access when the authorization service denies it' do
+    external_service_deny_access(user, project)
+
+    subject
+
+    expect(response).to have_gitlab_http_status(403)
+  end
+end

spec/support/shared_examples/finders/finder_with_external_authorization_enabled.rb

+require 'spec_helper'
+
+shared_examples 'a finder with external authorization service' do
+  include ExternalAuthorizationServiceHelpers
+
+  let(:user) { create(:user) }
+  let(:project) { create(:project) }
+
+  before do
+    project.add_maintainer(user)
+  end
+
+  it 'finds the subject' do
+    expect(described_class.new(user).execute).to include(subject)
+  end
+
+  context 'with an external authorization service' do
+    before do
+      enable_external_authorization_service_check
+    end
+
+    it 'does not include the subject when no project was given' do
+      expect(described_class.new(user).execute).not_to include(subject)
+    end
+
+    it 'includes the subject when a project id was given' do
+      expect(described_class.new(user, project_params).execute).to include(subject)
+    end
+  end
+end

spec/validators/x509_certificate_credentials_validator_spec.rb

+require 'spec_helper'
+
+describe X509CertificateCredentialsValidator do
+  let(:certificate_data) { File.read('spec/fixtures/x509_certificate.crt') }
+  let(:pkey_data) { File.read('spec/fixtures/x509_certificate_pk.key') }
+
+  let(:validatable) do
+    Class.new do
+      include ActiveModel::Validations
+
+      attr_accessor :certificate, :private_key, :passphrase
+
+      def initialize(certificate, private_key, passphrase = nil)
+        @certificate, @private_key, @passphrase = certificate, private_key, passphrase
+      end
+    end
+  end
+
+  subject(:validator) do
+    described_class.new(certificate: :certificate, pkey: :private_key)
+  end
+
+  it 'is not valid when the certificate is not valid' do
+    record = validatable.new('not a certificate', nil)
+
+    validator.validate(record)
+
+    expect(record.errors[:certificate]).to include('is not a valid X509 certificate.')
+  end
+
+  it 'is not valid without a certificate' do
+    record = validatable.new(nil, nil)
+
+    validator.validate(record)
+
+    expect(record.errors[:certificate]).not_to be_empty
+  end
+
+  context 'when a valid certificate is passed' do
+    let(:record) { validatable.new(certificate_data, nil) }
+
+    it 'does not track an error for the certificate' do
+      validator.validate(record)
+
+      expect(record.errors[:certificate]).to be_empty
+    end
+
+    it 'adds an error when not passing a correct private key' do
+      validator.validate(record)
+
+      expect(record.errors[:private_key]).to include('could not read private key, is the passphrase correct?')
+    end
+
+    it 'has no error when the private key is correct' do
+      record.private_key = pkey_data
+
+      validator.validate(record)
+
+      expect(record.errors).to be_empty
+    end
+  end
+
+  context 'when using a passphrase' do
+    let(:passphrase_certificate_data) { File.read('spec/fixtures/passphrase_x509_certificate.crt') }
+    let(:passphrase_pkey_data) { File.read('spec/fixtures/passphrase_x509_certificate_pk.key') }
+
+    let(:record) { validatable.new(passphrase_certificate_data, passphrase_pkey_data, '5iveL!fe') }
+
+    subject(:validator) do
+      described_class.new(certificate: :certificate, pkey: :private_key, pass: :passphrase)
+    end
+
+    it 'is valid with the correct data' do
+      validator.validate(record)
+
+      expect(record.errors).to be_empty
+    end
+
+    it 'adds an error when the passphrase is wrong' do
+      record.passphrase = 'wrong'
+
+      validator.validate(record)
+
+      expect(record.errors[:private_key]).not_to be_empty
+    end
+  end
+end