Parse.com cloud code check user before allowing login -

i using following code allow login ios , android apps. 1 of our paying customers has hundreds of users (who use same domain in email i.e @mycompany.com) need stopped using app immediately.

i cannot re-publish client app takes time review etc. how can prevent login group of users cloud code.

 parse.user.login(user.username.tolowercase(), user.password, {           success: function(user) {              user.set("platform", ionic.platform.device());             user.set("os", ionic.platform.platform());             user.save(null, {               success: function(user) {                 console.log('ok');               },               error: function(err) {                 console.log('error setting device');               }             }); 

is there beforesave on session class?