Question

I have an ASP.NET MVC based application that allows different levels of access depending on the user. The way it currently works is when a user accesses a page, a check is done against the database to determine the rights that user has. The view is then selected based on the level of access that user has. Some users see more data and have more functionality available to them than do others. Each page also makes a variety of ajax calls to display and update the data displayed on the page.

My question is what is the best way to ensure that a particular ajax call originated from the view and was not crafted manually to return or update data the user does not have access to? I would prefer not to have to go to the database to re-check every time an ajax call is made since that was already done when the user initially loaded the page.

Answer 1

Check out the Authorize Attribute, you can put it on an entire controller or just specific methods within your controller.

Examples:

[Authorize(Roles = "Administrator")]
public class AdminController : Controller
{
 //your code here
}

or

public class AdminController : Controller
{
    //Available to everyone
    public ActionResult Index()
    {
        return View();
    }

    //Just available to users in the Administrator role.
    [Authorize(Roles = "Administrator")]
    public ActionResult AdminOnlyIndex()
    {
        return View();
    }
}

Alternately, you can write a custom Authorize attribute to provide your own logic.

public class CustomAuthorizeAttribute : AuthorizeAttribute 
{           
    protected override bool AuthorizeCore(HttpContextBase httpContext)     
    {
        IPrincipal user = httpContext.User;     
        var validRoles = Roles.Split(',');//Roles will be a parameter when you use the Attribute        
        List<String> userRoles = GetRolesFromDb(user);//This will be a call to your database to get the roles the user is in.

        return validRoles.Intersect(userRoles).Any();
    }
} 

To use:

 [CustomAuthorizeAttribute(Roles = "Admin,Superuser")] 
 public class AdminController : Controller {

 }