How do I enable ssl for all controllers in mvc application

The [RequireHttps] attribute is inherited, so you could create a base controller, apply the attribute to that, and then derive all your controllers from that base.

[RequireHttps]
public abstract class BaseController : Controller
{}

public class HomeController : BaseController
{}

public class FooController : BaseController
{}

Use the RegisterGlobalFilters method in your FiltersConfig.

public class FilterConfig
{
    public static void RegisterGlobalFilters(GlobalFilterCollection filters)
    {
        filters.Add(new HandleErrorAttribute());
        filters.Add(new RequireHttpsAttribute());
    }
}