Add rate-limit of TOTP authentication attempts at controller level (#28801)

app/controllers/auth/sessions_controller.rb

@@ -1,6 +1,10 @@
 # frozen_string_literal: true
 
 class Auth::SessionsController < Devise::SessionsController
+  include Redisable
+
+  MAX_2FA_ATTEMPTS_PER_HOUR = 10
+
   layout 'auth'
 
   skip_before_action :check_self_destruct!
@@ -130,9 +134,23 @@ class Auth::SessionsController < Devise::SessionsController
     session.delete(:attempt_user_updated_at)
   end
 
+  def clear_2fa_attempt_from_user(user)
+    redis.del(second_factor_attempts_key(user))
+  end
+
+  def check_second_factor_rate_limits(user)
+    attempts, = redis.multi do |multi|
+      multi.incr(second_factor_attempts_key(user))
+      multi.expire(second_factor_attempts_key(user), 1.hour)
+    end
+
+    attempts >= MAX_2FA_ATTEMPTS_PER_HOUR
+  end
+
   def on_authentication_success(user, security_measure)
     @on_authentication_success_called = true
 
+    clear_2fa_attempt_from_user(user)
     clear_attempt_from_session
 
     user.update_sign_in!(new_sign_in: true)
@@ -164,4 +182,8 @@ class Auth::SessionsController < Devise::SessionsController
       user_agent: request.user_agent
     )
   end
+
+  def second_factor_attempts_key(user)
+    "2fa_auth_attempts:#{user.id}:#{Time.now.utc.hour}"
+  end
 end

app/controllers/concerns/auth/two_factor_authentication_concern.rb

@@ -66,6 +66,11 @@ module Auth::TwoFactorAuthenticationConcern
   end
 
   def authenticate_with_two_factor_via_otp(user)
+    if check_second_factor_rate_limits(user)
+      flash.now[:alert] = I18n.t('users.rate_limited')
+      return prompt_for_two_factor(user)
+    end
+
     if valid_otp_attempt?(user)
       on_authentication_success(user, :otp)
     else