Target user role in validation hook

For the purpose of restricting certain fields in a data model from being edited by any user, I should be able to target the current user's role in a validation hook.

Something like

 async function run() {
   if (context.user.role != 'admin') {
     return {
       level: 'error',
       message: 'only users with admin access can edit this field'
     }
   }
 }
 return run();