add CAS authentication support

CHANGELOG

@@ -66,6 +66,7 @@ v 8.2.3
 v 8.2.3
   - Webhook payload has an added, modified and removed properties for each commit
   - Fix 500 error when creating a merge request that removes a submodule
+  - Add CAS support (tduehr)
 
 v 8.2.2
   - Fix 404 in redirection after removing a project (Stan Hu)

Gemfile

@@ -23,6 +23,7 @@ gem 'devise-async',           '~> 0.9.0'
 gem 'doorkeeper',             '~> 2.2.0'
 gem 'omniauth',               '~> 1.2.2'
 gem 'omniauth-bitbucket',     '~> 0.0.2'
+gem 'omniauth-cas3',          '~> 1.1.2'
 gem 'omniauth-facebook',      '~> 3.0.0'
 gem 'omniauth-github',        '~> 1.1.1'
 gem 'omniauth-gitlab',        '~> 1.0.0'

Gemfile.lock

@@ -458,6 +458,10 @@ GEM
       multi_json (~> 1.7)
       omniauth (~> 1.1)
       omniauth-oauth (~> 1.0)
+    omniauth-cas3 (1.1.3)
+      addressable (~> 2.3)
+      nokogiri (~> 1.6.6)
+      omniauth (~> 1.2)
     omniauth-facebook (3.0.0)
       omniauth-oauth2 (~> 1.2)
     omniauth-github (1.1.2)
@@ -913,6 +917,7 @@ DEPENDENCIES
   octokit (~> 3.7.0)
   omniauth (~> 1.2.2)
   omniauth-bitbucket (~> 0.0.2)
+  omniauth-cas3 (~> 1.1.2)
   omniauth-facebook (~> 3.0.0)
   omniauth-github (~> 1.1.1)
   omniauth-gitlab (~> 1.0.0)

app/controllers/application_controller.rb

@@ -10,6 +10,7 @@ class ApplicationController < ActionController::Base
 
   before_action :authenticate_user_from_token!
   before_action :authenticate_user!
+  before_action :validate_user_service_ticket!
   before_action :reject_blocked!
   before_action :check_password_expiration
   before_action :ldap_security_check
@@ -202,6 +203,20 @@ def add_gon_variables
     end
   end
 
+  def validate_user_service_ticket!
+    return unless signed_in? && session[:service_tickets]
+
+    valid = session[:service_tickets].all? do |provider, ticket|
+      Gitlab::OAuth::Session.valid?(provider, ticket)
+    end
+
+    unless valid
+      session[:service_tickets] = nil
+      sign_out current_user
+      redirect_to new_user_session_path
+    end
+  end
+
   def check_password_expiration
     if current_user && current_user.password_expires_at && current_user.password_expires_at < Time.now  && !current_user.ldap_user?
       redirect_to new_profile_password_path and return

app/controllers/omniauth_callbacks_controller.rb

 class OmniauthCallbacksController < Devise::OmniauthCallbacksController
 
-  protect_from_forgery except: [:kerberos, :saml]
+  protect_from_forgery except: [:kerberos, :saml, :cas3]
 
   Gitlab.config.omniauth.providers.each do |provider|
     define_method provider['name'] do
@@ -42,6 +42,14 @@ def omniauth_error
     render 'errors/omniauth_error', layout: "errors", status: 422
   end
 
+  def cas3
+    ticket = params['ticket']
+    if ticket
+      handle_service_ticket oauth['provider'], ticket
+    end
+    handle_omniauth
+  end
+
   private
 
   def handle_omniauth
@@ -84,6 +92,12 @@ def handle_omniauth
     redirect_to new_user_session_path
   end
 
+  def handle_service_ticket provider, ticket
+    Gitlab::OAuth::Session.create provider, ticket
+    session[:service_tickets] ||= {}
+    session[:service_tickets][provider] = ticket
+  end
+
   def oauth
     @oauth ||= request.env['omniauth.auth']
   end

config/gitlab.yml.example

@@ -287,6 +287,15 @@ production: &base
     # arguments, followed by optional 'args' which can be either a hash or an array.
     # Documentation for this is available at http://doc.gitlab.com/ce/integration/omniauth.html
     providers:
+      # See omniauth-cas3 for more configuration details
+      # - { name: 'cas3',
+      #     label: 'cas3',
+      #     args: {
+      #             url: 'https://sso.example.com',
+      #             disable_ssl_verification: false,
+      #             login_url: '/cas/login',
+      #             service_validate_url: '/cas/p3/serviceValidate',
+      #             logout_url: '/cas/logout'} }
       # - { name: 'github',
       #     app_id: 'YOUR_APP_ID',
       #     app_secret: 'YOUR_APP_SECRET',
@@ -324,6 +333,10 @@ production: &base
       #       application_name: 'YOUR_APP_NAME',
       #       application_password: 'YOUR_APP_PASSWORD' } }
 
+    # SSO maximum session duration in seconds. Defaults to CAS default of 8 hours.
+    # cas3:
+    #   session_duration: 28800
+
   # Shared file storage settings
   shared:
     # path: /mnt/gitlab # Default: shared

config/initializers/1_settings.rb

@@ -126,6 +126,10 @@ def base_gitlab_url
 Settings.omniauth['auto_link_ldap_user'] = false if Settings.omniauth['auto_link_ldap_user'].nil?
 
 Settings.omniauth['providers']  ||= []
+Settings.omniauth['cas3'] ||= Settingslogic.new({})
+Settings.omniauth.cas3['session_duration'] ||= 8.hours
+Settings.omniauth['session_tickets'] ||= Settingslogic.new({})
+Settings.omniauth.session_tickets['cas3'] = 'ticket'
 
 Settings['shared'] ||= Settingslogic.new({})
 Settings.shared['path'] = File.expand_path(Settings.shared['path'] || "shared", Rails.root)

config/initializers/devise.rb

@@ -241,6 +241,16 @@
       # An Array from the configuration will be expanded.
       provider_arguments.concat provider['args']
     when Hash
+      # Add procs for handling SLO
+      if provider['name'] == 'cas3'
+        provider['args'][:on_single_sign_out]  = lambda do |request|
+          ticket = request.params[:session_index]
+          raise "Service Ticket not found." unless Gitlab::OAuth::Session.valid?(:cas3, ticket)
+          Gitlab::OAuth::Session.destroy(:cas3, ticket)
+          true
+        end
+      end
+
       # A Hash from the configuration will be passed as is.
       provider_arguments << provider['args'].symbolize_keys
     end

doc/integration/cas.md

+# CAS OmniAuth Provider
+
+To enable the CAS OmniAuth provider you must register your application with your CAS instance. This requires the service URL gitlab will supply to CAS. It should be something like: `https://gitlab.example.com:443/users/auth/cas3/callback?url`. By default handling for SLO is enabled, you only need to configure CAS for backchannel logout.
+
+1.  On your GitLab server, open the configuration file.
+
+    For omnibus package:
+
+    ```sh
+      sudo editor /etc/gitlab/gitlab.rb
+    ```
+
+    For instalations from source:
+
+    ```sh
+      cd /home/git/gitlab
+
+      sudo -u git -H editor config/gitlab.yml
+    ```
+
+1.  See [Initial OmniAuth Configuration](omniauth.md#initial-omniauth-configuration) for initial settings.
+
+1.  Add the provider configuration:
+
+    For omnibus package:
+
+    ```ruby
+      gitlab_rails['omniauth_providers'] = [
+        {
+          name: "cas3",
+          label: "cas",
+          args: {
+                  url: 'CAS_SERVER',
+                  login_url: '/CAS_PATH/login',
+                  service_validate_url: '/CAS_PATH/p3/serviceValidate',
+                  logout_url: '/CAS_PATH/logout'} }
+          }
+        }
+      ]
+    ```
+
+    For installations from source:
+
+    ```
+      - { name: 'cas3',
+          label: 'cas',
+          args: {
+                  url: 'CAS_SERVER',
+                  login_url: '/CAS_PATH/login',
+                  service_validate_url: '/CAS_PATH/p3/serviceValidate',
+                  logout_url: '/CAS_PATH/logout'} }
+    ```
+
+1.  Change 'CAS_PATH' to the root of your CAS instance (ie. `cas`).
+
+1.  If your CAS instance does not use default TGC lifetimes, update the `cas3.session_duration` to at least the current TGC maximum lifetime. To explicitly disable SLO, regardless of CAS settings, set this to 0.
+
+1.  Save the configuration file.
+
+1.  Restart GitLab for the changes to take effect.
+
+On the sign in page there should now be a CAS tab in the sign in form.
\ No newline at end of file

lib/gitlab/o_auth/session.rb

+module Gitlab
+  module OAuth
+    module Session
+      def self.create(provider, ticket)
+        Rails.cache.write("gitlab:#{provider}:#{ticket}", ticket, expires_in: Gitlab.config.omniauth.cas3.session_duration)
+      end
+
+      def self.destroy(provider, ticket)
+        Rails.cache.delete("gitlab:#{provider}:#{ticket}")
+      end
+
+      def self.valid?(provider, ticket)
+        Rails.cache.read("gitlab:#{provider}:#{ticket}").present?
+      end
+    end
+  end
+end