Get an instance of an interface from Unity

I'm trying to set up a custom authentication filter in my MVC app, but I need to have a link to my user service in the authentication filter. I am setting up my services with Unity like this:

    private static Lazy<IUnityContainer> container = new Lazy<IUnityContainer>(() =>
    {
        var container = new UnityContainer();
        RegisterTypes(container);
        return container;
    });

    public static IUnityContainer GetConfiguredContainer()
    {
        return container.Value;
    }

    public static void RegisterTypes(IUnityContainer container)
    {

        // container.LoadConfiguration();

        // TODO: Register your types here
        container.RegisterType<IUserService, UserService>();

    }

[assembly: WebActivatorEx.PreApplicationStartMethod(typeof(GERPWeb.App_Start.UnityWebActivator), "Start")]
[assembly: WebActivatorEx.ApplicationShutdownMethod(typeof(GERPWeb.App_Start.UnityWebActivator), "Shutdown")]

namespace APP.App_Start
{
/// <summary>Provides the bootstrapping for integrating Unity with ASP.NET MVC.</summary>
public static class UnityWebActivator
{
    /// <summary>Integrates Unity when the application starts.</summary>
    public static void Start() 
    {
        var container = UnityConfig.GetConfiguredContainer();

        FilterProviders.Providers.Remove(FilterProviders.Providers.OfType<FilterAttributeFilterProvider>().First());
        FilterProviders.Providers.Add(new UnityFilterAttributeFilterProvider(container));

        DependencyResolver.SetResolver(new UnityDependencyResolver(container));

        // TODO: Uncomment if you want to use PerRequestLifetimeManager
        // Microsoft.Web.Infrastructure.DynamicModuleHelper.DynamicModuleUtility.RegisterModule(typeof(UnityPerRequestHttpModule));
    }

    /// <summary>Disposes the Unity container when the application is shut down.</summary>
    public static void Shutdown()
    {
        var container = UnityConfig.GetConfiguredContainer();
        container.Dispose();
    }
}

      

        
        
        
      

    

This works great wherever I can have a constructor, for example:

public class UserController : BaseController
{

    private readonly IUserService _userService;

    public CustomerController(IUserService userService)
    {
        _userService = userService;

    }

      

        
        
        
      

    

However, I cannot have one of my authentication filter:

public class BasicAuthorization : AuthorizeAttribute
{
    public override void OnAuthorization(AuthorizationContext filterContext)
    {
        //see if we can skip the authorization
        bool skipAuthorization = filterContext.ActionDescriptor.IsDefined(typeof(AllowAnonymousAttribute), true) ||
                                 filterContext.ActionDescriptor.ControllerDescriptor.IsDefined(
                                     typeof(AllowAnonymousAttribute), true);

        if (!skipAuthorization)
        {
            //var userService = ServiceLocator.Current.GetInstance<IUserService>();
            //get instance of user service here


            base.OnAuthorization(filterContext);
        }
    }
}

      

        
        
        
      

    

Then in my FilterConfig.cs:

    public static void RegisterGlobalFilters(GlobalFilterCollection filters)
    {
        filters.Add(new BasicAuthorization());
        filters.Add(new HandleErrorAttribute());
    }

      

        
        
        
      

    

I found a link to something called a service locator and tried to use it to the best of my ability, but I think I am missing something as I am getting ServiceLocationProvider must be set.

in this line and all google links are for WPF.

What am I missing here?