From 6da135a493cc039d92bb5925c2a1ef66025623bf Mon Sep 17 00:00:00 2001
From: Claire <claire.github-309c@sitedethib.com>
Date: Sat, 6 Nov 2021 00:13:58 +0100
Subject: Fix reviving revoked sessions and invalidating login (#16943)

Up until now, we have used Devise's Rememberable mechanism to re-log users
after the end of their browser sessions. This mechanism relies on a signed
cookie containing a token. That token was stored on the user's record,
meaning it was shared across all logged in browsers, meaning truly revoking
a browser's ability to auto-log-in involves revoking the token itself, and
revoking access from *all* logged-in browsers.

We had a session mechanism that dynamically checks whether a user's session
has been disabled, and would log out the user if so. However, this would only
clear a session being actively used, and a new one could be respawned with
the `remember_user_token` cookie.

In practice, this caused two issues:
- sessions could be revived after being closed from /auth/edit (security issue)
- auto-log-in would be disabled for *all* browsers after logging out from one
  of them

This PR removes the `remember_token` mechanism and treats the `_session_id`
cookie/token as a browser-specific `remember_token`, fixing both issues.
---
 config/initializers/devise.rb | 39 ++++++++++++++++++++++++++++++++++++---
 1 file changed, 36 insertions(+), 3 deletions(-)

(limited to 'config/initializers')

diff --git a/config/initializers/devise.rb b/config/initializers/devise.rb
index ef612e177..5232e6cfd 100644
--- a/config/initializers/devise.rb
+++ b/config/initializers/devise.rb
@@ -1,3 +1,5 @@
+require 'devise/strategies/authenticatable'
+
 Warden::Manager.after_set_user except: :fetch do |user, warden|
   if user.session_active?(warden.cookies.signed['_session_id'] || warden.raw_session['auth_id'])
     session_id = warden.cookies.signed['_session_id'] || warden.raw_session['auth_id']
@@ -72,17 +74,48 @@ module Devise
   mattr_accessor :ldap_uid_conversion_replace
   @@ldap_uid_conversion_replace = nil
 
-  class Strategies::PamAuthenticatable
-    def valid?
-      super && ::Devise.pam_authentication
+  module Strategies
+    class PamAuthenticatable
+      def valid?
+        super && ::Devise.pam_authentication
+      end
+    end
+
+    class SessionActivationRememberable < Authenticatable
+      def valid?
+        @session_cookie = nil
+        session_cookie.present?
+      end
+
+      def authenticate!
+        resource = SessionActivation.find_by(session_id: session_cookie)&.user
+
+        unless resource
+          cookies.delete('_session_id')
+          return pass
+        end
+
+        if validate(resource)
+          success!(resource)
+        end
+      end
+
+      private
+
+      def session_cookie
+        @session_cookie ||= cookies.signed['_session_id']
+      end
     end
   end
 end
 
+Warden::Strategies.add(:session_activation_rememberable, Devise::Strategies::SessionActivationRememberable)
+
 Devise.setup do |config|
   config.warden do |manager|
     manager.default_strategies(scope: :user).unshift :two_factor_ldap_authenticatable if Devise.ldap_authentication
     manager.default_strategies(scope: :user).unshift :two_factor_pam_authenticatable  if Devise.pam_authentication
+    manager.default_strategies(scope: :user).unshift :session_activation_rememberable
     manager.default_strategies(scope: :user).unshift :two_factor_authenticatable
     manager.default_strategies(scope: :user).unshift :two_factor_backupable
   end
-- 
cgit