Skip two factor challenge in account module middleware

Fixes issue with infinite redirect when trying to access the challenge
page.

core/Middleware/AccountModuleMiddleware.php

@@ -32,6 +32,7 @@
 use OCP\Authentication\IAccountModuleController;
 use OCP\ILogger;
 use OCP\IUserSession;
+use OC\Core\Controller\TwoFactorChallengeController;
 
 /**
  * Class AccountModuleMiddleware
@@ -94,6 +95,11 @@ public function beforeController($controller, $methodName) {
 			return;
 		}
 
+		if ($controller instanceof TwoFactorChallengeController) {
+			// Don't block two factor challenge
+			return;
+		}
+
 		if ($this->session->isLoggedIn()) {
 			$user = $this->session->getUser();
 			if ($user === null) {