Entity framework is based on DML stuff (
data manipulation), so using it for CRUD operations won't be a bad idea. But creating a login system on the top of it, would not be a good idea. You would have to create a lot of modules and other stuff. So, don't!
Instead of this, you can use
ASP.NET Identity[
^]. Identity has a lot of good features, and allows you to take controls of everything (
yes, everything) that goes on under the hood. You can use the API to create your own services and use them in your application, change how the Identity system works, add more packages to it and so on.
So, instead of using Entity framework for user logins and permissions (
groups or roles, right?) you should use
ASP.NET Identity.