Customizing authorization in ASP.NET MVC

Question

My Controller class is decorated with an AuthorizeAttribute to protect the actions:

[Authorize(Roles = "User Level 2")]
public class BuyController : Controller
{
    ...
}

Anytime an action is invoked but the user is not in at least the role "User Level 2" he is automatically redirected to the login page with a url like this:

http://localhost:1436/Account/Login?ReturnUrl=%2fBuy

If the user is already logged in, but doesn't have the right security level, this is not an optimal behavior! It would make more sense to display a page which informs the user about the missing level instead of showing the login page.

What can I do to customize this behavior? Is it possible to pass the required user level to the Login action somehow?

Answer 1

You can build your own authorize attribute like this:

public class ClubAuthorizeAttribute : AuthorizeAttribute
{
public override void OnAuthorization(AuthorizationContext filterContext)
{
  base.OnAuthorization(filterContext);
  if (filterContext.Cancel && filterContext.Result is HttpUnauthorizedResult)
  {
    filterContext.Result = new RedirectToRouteResult(
      new RouteValueDictionary {
      { "clubShortName", filterContext.RouteData.Values[ "clubShortName" ] },
      { "controller", "Account" },
      { "action", "Login" },
      { "ReturnUrl", filterContext.HttpContext.Request.RawUrl }
    });
  }
}
}

I used this to redirect to a specific club in a club membership site I am building. You could adapt this to your need. BTW, in my case I do redirect to the login page, but I check to see if the user is authorized and if so, display a message that they don't have the correct permissions. No doubt you could also add something to ViewData or TempData to display on the page, but I haven't tried that

EDIT AuthorizationContext.Cancel doesn't exist anymore in RC. "filterContext.Result is HttpUnauthorizedResult" seems to be enough : What happened to filterContext.Cancel (ASP.NET MVC)

Answer 2

Time has long passed since the last answer.

Since 2009, a lot of progress has been made in the authorization space. In particular, OASIS (the ones behind SAML) have standardized XACML, the eXtensible Access Control Markup Language.

XACML gives developers:

• a usage pattern
• an architecture
• a flexible authorization policy language

XACML is in line with attribute-based access control which NIST recommends be adopted in applications nowadays.

Have a look at this answer for more details.