How to implement Permission Based Access Control with Asp.Net Core

Question

I am trying to implement permission based access control with aspnet core. For dynamically managing user roles and permissions(create_product, delete_product etc.), they are stored in the database. Data Model is like https://i.stack.imgur.com/CHMPE.png

Before aspnet core (in MVC 5) i was using custom AuthorizeAttribute like below to handle the issue:

public class CustomAuthorizeAttribute : AuthorizeAttribute
{
    private readonly string _permissionName { get; set; }
    [Inject]
    public IAccessControlService _accessControlService { get; set; }

    public CustomAuthorizeAttribute(string permissionName = "")
    {
        _permissionName = permissionName;
    }

    public override void OnAuthorization(AuthorizationContext filterContext)
    {
        base.OnAuthorization(filterContext);
        var user = _accessControlService.GetUser();
        if (PermissionName != "" && !user.HasPermission(_permissionName))
        {
            // set error result
            filterContext.HttpContext.Response.StatusCode = 403;
            return;
        }
        filterContext.HttpContext.Items["CUSTOM_USER"] = user;
    }
}

Then i was using it in action method like below:

[HttpGet]
[CustomAuthorize(PermissionEnum.PERSON_LIST)]
public ActionResult Index(PersonListQuery query){ }

Additionally, i was using HttpContext.Items["CUSTOM_USER"] in views to show or hide html part:

@if (CurrentUser.HasPermission("<Permission Name>"))
{

}

When i decided to switch aspnet core, all my plan was failed. Because there was no virtual OnAuthorization method in the AuthorizeAttribute. I tried some ways to solve problem. Those are below:

• Using new policy based authorization(i think it is not suitable for my scenerio)

• Using custom AuthorizeAttribute and AuthorizationFilter(i read this post https://stackoverflow.com/a/35863514/5426333 but i couldn’t change it properly)

• Using custom middleware(how to get AuthorizeAttribute of current action?)

• Using ActionFilter(is it correct for security purpose?)

I couldn’t decide which way is the best for my scenerio and how to implement it.

First question: Is MVC5 implementation bad practice?

Second question: Do you have any suggest to implement aspnet core?

Answer 1

Based on the comments, here an example on how to use the policy based authorization:

public class PermissionRequirement : IAuthorizationRequirement
{
    public PermissionRequirement(PermissionEnum permission)
    {
         Permission = permission;
    }

    public PermissionEnum Permission { get; }
}

public class PermissionHandler : AuthorizationHandler<PermissionRequirement>
{
    private readonly IUserPermissionsRepository permissionRepository;

    public PermissionHandler(IUserPermissionsRepository permissionRepository)
    {
        if(permissionRepository == null)
            throw new ArgumentNullException(nameof(permissionRepository));

        this.permissionRepository = permissionRepository;
    }

    protected override void Handle(AuthorizationContext context, PermissionRequirement requirement)
    {
        if(context.User == null)
        {
            // no user authorizedd. Alternatively call context.Fail() to ensure a failure 
            // as another handler for this requirement may succeed
            return null;
        }

        bool hasPermission = permissionRepository.CheckPermissionForUser(context.User, requirement.Permission);
        if (hasPermission)
        {
            context.Succeed(requirement);
        }
    }
}

And register it in your Startup class:

services.AddAuthorization(options =>
{
    UserDbContext context = ...;
    foreach(var permission in context.Permissions) 
    {
        // assuming .Permission is enum
        options.AddPolicy(permission.Permission.ToString(),
            policy => policy.Requirements.Add(new PermissionRequirement(permission.Permission)));
    }
});

// Register it as scope, because it uses Repository that probably uses dbcontext
services.AddScope<IAuthorizationHandler, PermissionHandler>();

And finally in the controller

[HttpGet]
[Authorize(Policy = PermissionEnum.PERSON_LIST.ToString())]
public ActionResult Index(PersonListQuery query)
{
    ...
}

The advantage of this solution is that you can also have multiple handlers for a requirement, i.e. if first one succeed the second handler can determine it's a fail and you can use it with resource based authorization with little extra effort.

The policy based approach is the preferred way to do it by the ASP.NET Core team.

From blowdart:

We don't want you writing custom authorize attributes. If you need to do that we've done something wrong. Instead you should be writing authorization requirements.

Answer 2

I had same requirement and i have done it as below and it works fine for me. I am using .Net Core 2.0 Webapi

[AttributeUsage(AttributeTargets.Class | 
                         AttributeTargets.Method
                       , AllowMultiple = true
                       , Inherited = true)]
public class CheckAccessAttribute : AuthorizeAttribute, IAuthorizationFilter
{
  private string[] _permission;
  public CheckAccessAttribute(params string[] permission)
  {
      _permission = permission;
  }

  public void OnAuthorization(AuthorizationFilterContext context)
  {
     var user = context.HttpContext.User;

     if (!user.Identity.IsAuthenticated)
     {
        return;
     }

     IRepository service = 
     (IRepositoryWrapper)context.HttpContext.RequestServices.GetService(typeof(IRepository));
     var success = service.CheckAccess(userName, _permission.ToList());
     if (!success)
     {
        context.Result = JsonFormatter.GetErrorJsonObject(
                               CommonResource.error_unauthorized,
                               StatusCodeEnum.Forbidden);
        return;
     }
     return;
   }
}

In Controller use it like below

[HttpPost]
[CheckAccess(Permission.CreateGroup)]
public JsonResult POST([FromBody]Group group)
{
   // your code api code here.
}

Answer 3

For a solution that doesn't require you to add a policy for each permission see my answer for another question.

It lets you decorate your Controllers and Actions with any custom attributes you wish, and access them in your AuthorizationHandler.