ASP.NET Core 1 – Authorization using Policies

The goal of this post is to show how can we protect controller actions in ASP.NET Core 1 using Policies.

The whole code is available on GitHub: ASP.NET Core 1, Security using Policies.

With policies we don’t need to hard code anymore Roles or Names in our Authorize attribute. A policy is an authorization logic that contains one of more requirements.

How to use a policy?

The concept is very simple, once we have a defined policy we can add it to our Authorize attributes…

public IActionResult Info()
//... something that only good monsters can do

How to create a policy?

We have to define our policies in our Startup class, in ConfigureServices. We need a policy name, a list of valid authentication schemes and a list of requirements.

// Configure authorization
services.AddAuthorization(options => options.AddPolicy(CookieMonsterSecurity.OnlyGoodMonstersPolicy, policy =>
// Our own requirement logic...
policy.AddRequirements(new IsGoodMonsterRequirement());

We can add more than one requirement to our policy, there are some pre-build requirements:

  • policy.RequireAuthenticatedUser()
  • policy.RequireClaim(…)
  • policy.RequireRole(…)

But the more flexible way is to add a custom requirement, doing this we can write our own logic:

  • policy.AddRequirements(new IsGoodMonsterRequirement());

To write our requirement we use the base class AuthorizationHandler and implement the interface IAuthorizationRequirement.

This requirement checks that the user is authenticated and has the claim “MonsterTypeClaim” = “Good”

public class IsGoodMonsterRequirement : AuthorizationHandler<IsGoodMonsterRequirement>, IAuthorizationRequirement
protected override void Handle(AuthorizationContext context, IsGoodMonsterRequirement requirement)
Console.WriteLine("Is a good monster?");
if (!context.User.Identity.IsAuthenticated)
Console.WriteLine("... is authenticated...");
if (context.User.HasClaim(CookieMonsterSecurity.MonsterTypeClaim, CookieMonsterSecurity.MonsterTypes.Good))
Console.WriteLine("... and has the MonsterTypeClaim = MonsterTypes.Good!");