Develop Reference

asp.net core custom attribute to get object from filter

I am having some ActionFilters in my asp.net core mvc application, which validate some input data. For example, the client sends a userId inside the header, the filter loads that user from a repository, and validates, if the user exists, is active, has a license, and so on.
This filter is attached to a Controller method. The Controller method also needs to collect the same user object. Because of performance, I want to pass that user object, collected inside the filter, to the controller, so the controller does not need to load the same user object again. I know there are ways to do so, like mentioned here.
Because of clean code, I wonder if this would be possible, coding an attribute which defines what to retrieve, like the [FromBody] attribute does, for instance.
I could imagine this attribute named [FromFilter("User")], which takes a parameter to specify the key inside the HttpContext.Items
A basic implementation could be something like this:
[AttributeUsage(AttributeTargets.Parameter | AttributeTargets.Property, AllowMultiple = false, Inherited = true)]
public class FromFilterAttribute : Attribute, IBindingSourceMetadata, IModelNameProvider
{
/// <inheritdoc />
public BindingSource BindingSource => BindingSource.Custom;
/// <inheritdoc />
public string Name { get; set; }
}
Neither do I know if this would a be a good idea, nor how to implement such a feature. Hopefully someone can me point into the right direction

As far as I know, we couldn't directly pass the object from filter to action.
In my opinion, the best solution is creating a custom model binding and then find the user from the repository and pass the user to the action.
Since the model binding is triggered before the filter, you could get the custom model binding result from the ActionExecutingContext.
Order of execution:
UserModelBinder --> OnActionExecuting --> Index action
More details about to do it, you could refer to below codes:
Custom model binding:
public class UserModelBinder : IModelBinder
{
public Task BindModelAsync(ModelBindingContext bindingContext)
{
var model = new UserModel()
{
id = 1,
name = "test"
};
bindingContext.Result = ModelBindingResult.Success(model);
return Task.CompletedTask;
}
}
Controller action and OnActionExecuting method:
OnActionExecuting:
public override void OnActionExecuting(ActionExecutingContext context)
{
//ActionArguments["user"] is the parameter name of the action parameter
var user = context.ActionArguments["user"] as UserModel;
// Do something before the action executes.
base.OnActionExecuting(context);
}
Action method:
public async Task<IActionResult> Index([ModelBinder(BinderType = typeof(UserModelBinder))] UserModel user)
{
int i =0;
return View();
}
Result:
Filter onexecuting:
Action parameter:

You can use HttpContext.Items for this and create HttpContextItemsModelBinder which will bind model from HttpContext.Items
public class HttpContextItemsModelBinder : IModelBinder
{
public Task BindModelAsync(ModelBindingContext bindingContext)
{
var items = bindingContext.HttpContext.Items;
string name = bindingContext.BinderModelName ?? bindingContext.FieldName;
bindingContext.Result = items.TryGetValue(name, out object item)
? ModelBindingResult.Success(item)
: ModelBindingResult.Failed();
return Task.CompletedTask;
}
}
Create and register model binder provider
public static class CustomBindingSources
{
public static BindingSource HttpContextItems { get; } = new BindingSource("HttpContextItems", "HttpContext Items", true, true);
}
public class HttpContextItemsModelBinderProvider : IModelBinderProvider
{
public IModelBinder GetBinder(ModelBinderProviderContext context)
{
if (context.BindingInfo.BindingSource == CustomBindingSources.HttpContextItems)
{
return new HttpContextItemsModelBinder();
}
return null;
}
}
In Startup.cs
services
.AddMvc(options =>
{
options.ModelBinderProviders.Insert(0, new HttpContextItemsModelBinderProvider());
//...
})
Create an attribute which will set correct BindingSource to use HttpContextItemsModelBinder
[AttributeUsage(AttributeTargets.Parameter | AttributeTargets.Property, AllowMultiple = false, Inherited = true)]
public class FromHttpContextItemsAttribute : Attribute, IBindingSourceMetadata, IModelNameProvider
{
public string Name { get; set; }
public BindingSource BindingSource => CustomBindingSources.HttpContextItems;
public FromHttpContextItemsAttribute(string name)
{
Name = name;
}
public FromHttpContextItemsAttribute() { }
}
Usage:
//in controller
[HttpGet]
[ValidateUserFilter]
public IActionResult TestHttpContextItems([FromHttpContextItems("UserItem")]UserItemModel model)
{
return Ok(model);
}
//your action filter
public class ValidateUserFilterAttribute : ActionFilterAttribute, IAuthorizationFilter
{
public override void OnActionExecuting(ActionExecutingContext context)
{
//...
}
public void OnAuthorization(AuthorizationFilterContext context)
{
var model = new UserItemModel
{
Id = 45,
Name = "Some user name"
};
context.HttpContext.Items["UserItem"] = model;
}
}
Important note
Pay attention that I save user model to HttpContext.Items during OnAuthorization and not OnActionExecuting because model binding happens before any action filters run, so HttpContext.Items won't contain user and model binding will fail. You might need to adjust filter code to your needs and to make the solution work as expected.
Usage without specifying item name. Parameter name in action method should match key ("userModel") used to store value in HttpContext.Items:
//in controller
[HttpGet]
[ValidateUserFilter]
public IActionResult TestHttpContextItems([FromHttpContextItems]UserItemModel userModel)
{
return Ok(userModel);
}
//action filter
public class ValidateUserFilterAttribute : ActionFilterAttribute, IAuthorizationFilter
{
public override void OnActionExecuting(ActionExecutingContext context)
{
//...
}
public void OnAuthorization(AuthorizationFilterContext context)
{
//...
context.HttpContext.Items["userModel"] = model;
}
}

Check annotation schema from base class

Is there any way to check schema annotation from a base class?
Is simple to explain throw an example:
I have this 2 controllers
[Authorize]
public class HomeController : _baseController
{
//Some actions here
}
[AllowAnonymous]
public class OtherController : _baseController
{
//Some actions here
}
Then I have this base class which overrides OnActionExecuting. The objective is to perform some action if the controller has an annotation.
public class _baseController
{
public override void OnActionExecuting(ActionExecutingContext context)
{
base.OnActionExecuting(context);
if(context.Controller.hasAnnotation("Authorize")){
//do something
}
else if(context.Controller.hasAnnotation("AllowAnonymous")){
//do something
}
}
}
Obviously context.Controller.hasAnnotation is not a valid method. But you get the idea.

Further to my comment above, I have tested the following solution in ASP.Net Core 3.
public override void OnActionExecuting(ActionExecutingContext context)
{
var allowAnonAttr = Attribute.GetCustomAttribute(context.Controller.GetType(), typeof(AllowAnonymousAttribute));
if(allowAnonAttr != null)
{
// do something
}
}
In older versions of ASP.NET, you also have to reference System.Reflection to make use of the GetCustomAttribute extension.
Note that this solution works for attributes placed on the controller class itself (as asked in the question), but will not work for attributes placed on action methods. To get it to work for action methods, the below works:
public override void OnActionExecuting(ActionExecutingContext context)
{
var descriptor = context.ActionDescriptor as ControllerActionDescriptor;
var actionName = descriptor.ActionName;
var actionType = context.Controller.GetType().GetMethod(actionName);
var allowAnonAttr = Attribute.GetCustomAttribute(actionType, typeof(AllowAnonymousAttribute));
if(allowAnonAttr != null)
{
// do something
}
}

As suggested in the comments, the below should work for you:
public class _baseController
{
public override void OnActionExecuting(ActionExecutingContext context)
{
base.OnActionExecuting(context);
System.Attribute[] attrs = System.Attribute.GetCustomAttributes(context.Controller.GetType());
}
}

Custom authorization attribute implementation [duplicate]

I'm trying to make a custom authorization attribute in ASP.NET Core. In previous versions it was possible to override bool AuthorizeCore(HttpContextBase httpContext). But this no longer exists in AuthorizeAttribute.
What is the current approach to make a custom AuthorizeAttribute?
What I am trying to accomplish: I am receiving a session ID in the Header Authorization. From that ID I'll know whether a particular action is valid.

The approach recommended by the ASP.Net Core team is to use the new policy design which is fully documented here. The basic idea behind the new approach is to use the new [Authorize] attribute to designate a "policy" (e.g. [Authorize( Policy = "YouNeedToBe18ToDoThis")] where the policy is registered in the application's Startup.cs to execute some block of code (i.e. ensure the user has an age claim where the age is 18 or older).
The policy design is a great addition to the framework and the ASP.Net Security Core team should be commended for its introduction. That said, it isn't well-suited for all cases. The shortcoming of this approach is that it fails to provide a convenient solution for the most common need of simply asserting that a given controller or action requires a given claim type. In the case where an application may have hundreds of discrete permissions governing CRUD operations on individual REST resources ("CanCreateOrder", "CanReadOrder", "CanUpdateOrder", "CanDeleteOrder", etc.), the new approach either requires repetitive one-to-one mappings between a policy name and a claim name (e.g. options.AddPolicy("CanUpdateOrder", policy => policy.RequireClaim(MyClaimTypes.Permission, "CanUpdateOrder));), or writing some code to perform these registrations at run time (e.g. read all claim types from a database and perform the aforementioned call in a loop). The problem with this approach for the majority of cases is that it's unnecessary overhead.
While the ASP.Net Core Security team recommends never creating your own solution, in some cases this may be the most prudent option with which to start.
The following is an implementation which uses the IAuthorizationFilter to provide a simple way to express a claim requirement for a given controller or action:
public class ClaimRequirementAttribute : TypeFilterAttribute
{
public ClaimRequirementAttribute(string claimType, string claimValue) : base(typeof(ClaimRequirementFilter))
{
Arguments = new object[] {new Claim(claimType, claimValue) };
}
}
public class ClaimRequirementFilter : IAuthorizationFilter
{
readonly Claim _claim;
public ClaimRequirementFilter(Claim claim)
{
_claim = claim;
}
public void OnAuthorization(AuthorizationFilterContext context)
{
var hasClaim = context.HttpContext.User.Claims.Any(c => c.Type == _claim.Type && c.Value == _claim.Value);
if (!hasClaim)
{
context.Result = new ForbidResult();
}
}
}
[Route("api/resource")]
public class MyController : Controller
{
[ClaimRequirement(MyClaimTypes.Permission, "CanReadResource")]
[HttpGet]
public IActionResult GetResource()
{
return Ok();
}
}

I'm the asp.net security person. Firstly let me apologize that none of this is documented yet outside of the music store sample or unit tests, and it's all still being refined in terms of exposed APIs. Detailed documentation is here.
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.
Authorization acts upon Identities. Identities are created by authentication.
You say in comments you want to check a session ID in a header. Your session ID would be the basis for identity. If you wanted to use the Authorize attribute you'd write an authentication middleware to take that header and turn it into an authenticated ClaimsPrincipal. You would then check that inside an authorization requirement. Authorization requirements can be as complicated as you like, for example here's one that takes a date of birth claim on the current identity and will authorize if the user is over 18;
public class Over18Requirement : AuthorizationHandler<Over18Requirement>, IAuthorizationRequirement
{
public override void Handle(AuthorizationHandlerContext context, Over18Requirement requirement)
{
if (!context.User.HasClaim(c => c.Type == ClaimTypes.DateOfBirth))
{
context.Fail();
return;
}
var dobVal = context.User.FindFirst(c => c.Type == ClaimTypes.DateOfBirth).Value;
var dateOfBirth = Convert.ToDateTime(dobVal);
int age = DateTime.Today.Year - dateOfBirth.Year;
if (dateOfBirth > DateTime.Today.AddYears(-age))
{
age--;
}
if (age >= 18)
{
context.Succeed(requirement);
}
else
{
context.Fail();
}
}
}
Then in your ConfigureServices() function you'd wire it up
services.AddAuthorization(options =>
{
options.AddPolicy("Over18",
policy => policy.Requirements.Add(new Authorization.Over18Requirement()));
});
And finally, apply it to a controller or action method with
[Authorize(Policy = "Over18")]

It seems that with ASP.NET Core 2, you can again inherit AuthorizeAttribute, you just need to also implement IAuthorizationFilter (or IAsyncAuthorizationFilter):
[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, AllowMultiple = true, Inherited = true)]
public class CustomAuthorizeAttribute : AuthorizeAttribute, IAuthorizationFilter
{
private readonly string _someFilterParameter;
public CustomAuthorizeAttribute(string someFilterParameter)
{
_someFilterParameter = someFilterParameter;
}
public void OnAuthorization(AuthorizationFilterContext context)
{
var user = context.HttpContext.User;
if (!user.Identity.IsAuthenticated)
{
// it isn't needed to set unauthorized result
// as the base class already requires the user to be authenticated
// this also makes redirect to a login page work properly
// context.Result = new UnauthorizedResult();
return;
}
// you can also use registered services
var someService = context.HttpContext.RequestServices.GetService<ISomeService>();
var isAuthorized = someService.IsUserAuthorized(user.Identity.Name, _someFilterParameter);
if (!isAuthorized)
{
context.Result = new StatusCodeResult((int)System.Net.HttpStatusCode.Forbidden);
return;
}
}
}

Based on Derek Greer GREAT answer, i did it with enums.
Here is an example of my code:
public enum PermissionItem
{
User,
Product,
Contact,
Review,
Client
}
public enum PermissionAction
{
Read,
Create,
}
public class AuthorizeAttribute : TypeFilterAttribute
{
public AuthorizeAttribute(PermissionItem item, PermissionAction action)
: base(typeof(AuthorizeActionFilter))
{
Arguments = new object[] { item, action };
}
}
public class AuthorizeActionFilter : IAuthorizationFilter
{
private readonly PermissionItem _item;
private readonly PermissionAction _action;
public AuthorizeActionFilter(PermissionItem item, PermissionAction action)
{
_item = item;
_action = action;
}
public void OnAuthorization(AuthorizationFilterContext context)
{
bool isAuthorized = MumboJumboFunction(context.HttpContext.User, _item, _action); // :)
if (!isAuthorized)
{
context.Result = new ForbidResult();
}
}
}
public class UserController : BaseController
{
private readonly DbContext _context;
public UserController( DbContext context) :
base()
{
_logger = logger;
}
[Authorize(PermissionItem.User, PermissionAction.Read)]
public async Task<IActionResult> Index()
{
return View(await _context.User.ToListAsync());
}
}

You can create your own AuthorizationHandler that will find custom attributes on your Controllers and Actions, and pass them to the HandleRequirementAsync method.
public abstract class AttributeAuthorizationHandler<TRequirement, TAttribute> : AuthorizationHandler<TRequirement> where TRequirement : IAuthorizationRequirement where TAttribute : Attribute
{
protected override Task HandleRequirementAsync(AuthorizationHandlerContext context, TRequirement requirement)
{
var attributes = new List<TAttribute>();
var action = (context.Resource as AuthorizationFilterContext)?.ActionDescriptor as ControllerActionDescriptor;
if (action != null)
{
attributes.AddRange(GetAttributes(action.ControllerTypeInfo.UnderlyingSystemType));
attributes.AddRange(GetAttributes(action.MethodInfo));
}
return HandleRequirementAsync(context, requirement, attributes);
}
protected abstract Task HandleRequirementAsync(AuthorizationHandlerContext context, TRequirement requirement, IEnumerable<TAttribute> attributes);
private static IEnumerable<TAttribute> GetAttributes(MemberInfo memberInfo)
{
return memberInfo.GetCustomAttributes(typeof(TAttribute), false).Cast<TAttribute>();
}
}
Then you can use it for any custom attributes you need on your controllers or actions. For example to add permission requirements. Just create your custom attribute.
[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, AllowMultiple = true)]
public class PermissionAttribute : AuthorizeAttribute
{
public string Name { get; }
public PermissionAttribute(string name) : base("Permission")
{
Name = name;
}
}
Then create a Requirement to add to your Policy
public class PermissionAuthorizationRequirement : IAuthorizationRequirement
{
//Add any custom requirement properties if you have them
}
Then create the AuthorizationHandler for your custom attribute, inheriting the AttributeAuthorizationHandler that we created earlier. It will be passed an IEnumerable for all your custom attributes in the HandleRequirementsAsync method, accumulated from your Controller and Action.
public class PermissionAuthorizationHandler : AttributeAuthorizationHandler<PermissionAuthorizationRequirement, PermissionAttribute>
{
protected override async Task HandleRequirementAsync(AuthorizationHandlerContext context, PermissionAuthorizationRequirement requirement, IEnumerable<PermissionAttribute> attributes)
{
foreach (var permissionAttribute in attributes)
{
if (!await AuthorizeAsync(context.User, permissionAttribute.Name))
{
return;
}
}
context.Succeed(requirement);
}
private Task<bool> AuthorizeAsync(ClaimsPrincipal user, string permission)
{
//Implement your custom user permission logic here
}
}
And finally, in your Startup.cs ConfigureServices method, add your custom AuthorizationHandler to the services, and add your Policy.
services.AddSingleton<IAuthorizationHandler, PermissionAuthorizationHandler>();
services.AddAuthorization(options =>
{
options.AddPolicy("Permission", policyBuilder =>
{
policyBuilder.Requirements.Add(new PermissionAuthorizationRequirement());
});
});
Now you can simply decorate your Controllers and Actions with your custom attribute.
[Permission("AccessCustomers")]
public class CustomersController
{
[Permission("AddCustomer")]
IActionResult AddCustomer([FromBody] Customer customer)
{
//Add customer
}
}

What is the current approach to make a custom AuthorizeAttribute
For pure authorization scenarios (like restricting access to specific users only), the recommended approach is to use the new authorization block: https://github.com/aspnet/MusicStore/blob/1c0aeb08bb1ebd846726232226279bbe001782e1/samples/MusicStore/Startup.cs#L84-L92
public class Startup
{
public void ConfigureServices(IServiceCollection services)
{
services.Configure<AuthorizationOptions>(options =>
{
options.AddPolicy("ManageStore", policy => policy.RequireClaim("Action", "ManageStore"));
});
}
}
public class StoreController : Controller
{
[Authorize(Policy = "ManageStore"), HttpGet]
public async Task<IActionResult> Manage() { ... }
}
For authentication, it's best handled at the middleware level.
What are you trying to achieve exactly?

What?!
I decided to add another simple answer. B/c I find most of these answers a little overengineered. And also because I needed a way to GRANT authorization, not just DENY it. Most of the answers here offer a way to "tighten" security, but I wanted to "loosen" it. For example: "if some application setting is configured, then allow access to anonymous users".
public class MyAuthAttribute : Attribute, IAuthorizationFilter
{
public void OnAuthorization(AuthorizationFilterContext context)
{
//check access
if (CheckPermissions())
{
//all good, add optional code if you want. Or don't
}
else
{
//DENIED!
//return "ChallengeResult" to redirect to login page (for example)
context.Result = new ChallengeResult(CookieAuthenticationDefaults.AuthenticationScheme);
}
}
}
That's it. No need to mess with "policies", "claims", "handlers" and other [beep]
Usage:
// GET api/Get/5
[MyAuth]
public ActionResult<string> Get(int id)
{
return "blahblah";
}

The modern way is AuthenticationHandlers
in startup.cs add
services.AddAuthentication("BasicAuthentication").AddScheme<AuthenticationSchemeOptions, BasicAuthenticationHandler>("BasicAuthentication", null);
public class BasicAuthenticationHandler : AuthenticationHandler<AuthenticationSchemeOptions>
{
private readonly IUserService _userService;
public BasicAuthenticationHandler(
IOptionsMonitor<AuthenticationSchemeOptions> options,
ILoggerFactory logger,
UrlEncoder encoder,
ISystemClock clock,
IUserService userService)
: base(options, logger, encoder, clock)
{
_userService = userService;
}
protected override async Task<AuthenticateResult> HandleAuthenticateAsync()
{
if (!Request.Headers.ContainsKey("Authorization"))
return AuthenticateResult.Fail("Missing Authorization Header");
User user = null;
try
{
var authHeader = AuthenticationHeaderValue.Parse(Request.Headers["Authorization"]);
var credentialBytes = Convert.FromBase64String(authHeader.Parameter);
var credentials = Encoding.UTF8.GetString(credentialBytes).Split(new[] { ':' }, 2);
var username = credentials[0];
var password = credentials[1];
user = await _userService.Authenticate(username, password);
}
catch
{
return AuthenticateResult.Fail("Invalid Authorization Header");
}
if (user == null)
return AuthenticateResult.Fail("Invalid User-name or Password");
var claims = new[] {
new Claim(ClaimTypes.NameIdentifier, user.Id.ToString()),
new Claim(ClaimTypes.Name, user.Username),
};
var identity = new ClaimsIdentity(claims, Scheme.Name);
var principal = new ClaimsPrincipal(identity);
var ticket = new AuthenticationTicket(principal, Scheme.Name);
return AuthenticateResult.Success(ticket);
}
}
IUserService is a service that you make where you have user name and password.
basically it returns a user class that you use to map your claims on.
var claims = new[] {
new Claim(ClaimTypes.NameIdentifier, user.Id.ToString()),
new Claim(ClaimTypes.Name, user.Username),
};
Then you can query these claims and her any data you mapped, ther are quite a few, have a look at ClaimTypes class
you can use this in an extension method an get any of the mappings
public int? GetUserId()
{
if (context.User.Identity.IsAuthenticated)
{
var id=context.User.FindFirst(ClaimTypes.NameIdentifier);
if (!(id is null) && int.TryParse(id.Value, out var userId))
return userId;
}
return new Nullable<int>();
}
This new way, i think is better than the old way as shown here, both work
public class BasicAuthenticationAttribute : AuthorizationFilterAttribute
{
public override void OnAuthorization(HttpActionContext actionContext)
{
if (actionContext.Request.Headers.Authorization != null)
{
var authToken = actionContext.Request.Headers.Authorization.Parameter;
// decoding authToken we get decode value in 'Username:Password' format
var decodeauthToken = System.Text.Encoding.UTF8.GetString(Convert.FromBase64String(authToken));
// spliting decodeauthToken using ':'
var arrUserNameandPassword = decodeauthToken.Split(':');
// at 0th postion of array we get username and at 1st we get password
if (IsAuthorizedUser(arrUserNameandPassword[0], arrUserNameandPassword[1]))
{
// setting current principle
Thread.CurrentPrincipal = new GenericPrincipal(new GenericIdentity(arrUserNameandPassword[0]), null);
}
else
{
actionContext.Response = actionContext.Request.CreateResponse(HttpStatusCode.Unauthorized);
}
}
else
{
actionContext.Response = actionContext.Request.CreateResponse(HttpStatusCode.Unauthorized);
}
}
public static bool IsAuthorizedUser(string Username, string Password)
{
// In this method we can handle our database logic here...
return Username.Equals("test") && Password == "test";
}
}

If anyone just wants to validate a bearer token in the authorize phase using the current security practices you can,
add this to your Startup/ConfigureServices
services.AddSingleton<IAuthorizationHandler, BearerAuthorizationHandler>();
services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme).AddJwtBearer();
services.AddAuthorization(options => options.AddPolicy("Bearer",
policy => policy.AddRequirements(new BearerRequirement())
)
);
and this in your codebase,
public class BearerRequirement : IAuthorizationRequirement
{
public async Task<bool> IsTokenValid(SomeValidationContext context, string token)
{
// here you can check if the token received is valid
return true;
}
}
public class BearerAuthorizationHandler : AuthorizationHandler<BearerRequirement>
{
public BearerAuthorizationHandler(SomeValidationContext thatYouCanInject)
{
...
}
protected override async Task HandleRequirementAsync(AuthorizationHandlerContext context, BearerRequirement requirement)
{
var authFilterCtx = (Microsoft.AspNetCore.Mvc.Filters.AuthorizationFilterContext)context.Resource;
string authHeader = authFilterCtx.HttpContext.Request.Headers["Authorization"];
if (authHeader != null && authHeader.Contains("Bearer"))
{
var token = authHeader.Replace("Bearer ", string.Empty);
if (await requirement.IsTokenValid(thatYouCanInject, token))
{
context.Succeed(requirement);
}
}
}
}
If the code doesn't reach context.Succeed(...) it will Fail anyway (401).
And then in your controllers you can use
[Authorize(Policy = "Bearer", AuthenticationSchemes = JwtBearerDefaults.AuthenticationScheme)]

The below code worked for me in .Net Core 5
[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method)]
public class AccessAuthorizationAttribute : AuthorizeAttribute, IAuthorizationFilter
{
public string Module { get; set; } //Permission string to get from controller
public AccessAuthorizationAttribute(string module)
{
Module = module;
}
public void OnAuthorization(AuthorizationFilterContext context)
{
//Validate if any permissions are passed when using attribute at controller or action level
if (string.IsNullOrEmpty(Module))
{
//Validation cannot take place without any permissions so returning unauthorized
context.Result = new UnauthorizedResult();
return;
}
if (hasAccess)
{
return;
}
context.Result = new UnauthorizedResult();
return;
}
}

The accepted answer (https://stackoverflow.com/a/41348219/4974715) is not realistically maintainable or suitable because "CanReadResource" is being used as a claim (but should essentially be a policy in reality, IMO). The approach at the answer is not OK in the way it was used, because if an action method requires many different claims setups, then with that answer you would have to repeatedly write something like...
[ClaimRequirement(MyClaimTypes.Permission, "CanReadResource")]
[ClaimRequirement(MyClaimTypes.AnotherPermision, "AnotherClaimVaue")]
//and etc. on a single action.
So, imagine how much coding that would take. Ideally, "CanReadResource" is supposed to be a policy that uses many claims to determine if a user can read a resource.
What I do is I create my policies as an enumeration and then loop through and set up the requirements like thus...
services.AddAuthorization(authorizationOptions =>
{
foreach (var policyString in Enum.GetNames(typeof(Enumerations.Security.Policy)))
{
authorizationOptions.AddPolicy(
policyString,
authorizationPolicyBuilder => authorizationPolicyBuilder.Requirements.Add(new DefaultAuthorizationRequirement((Enumerations.Security.Policy)Enum.Parse(typeof(Enumerations.Security.Policy), policyWrtString), DateTime.UtcNow)));
/* Note that thisn does not stop you from
configuring policies directly against a username, claims, roles, etc. You can do the usual.
*/
}
});
The DefaultAuthorizationRequirement class looks like...
public class DefaultAuthorizationRequirement : IAuthorizationRequirement
{
public Enumerations.Security.Policy Policy {get; set;} //This is a mere enumeration whose code is not shown.
public DateTime DateTimeOfSetup {get; set;} //Just in case you have to know when the app started up. And you may want to log out a user if their profile was modified after this date-time, etc.
}
public class DefaultAuthorizationHandler : AuthorizationHandler<DefaultAuthorizationRequirement>
{
private IAServiceToUse _aServiceToUse;
public DefaultAuthorizationHandler(
IAServiceToUse aServiceToUse
)
{
_aServiceToUse = aServiceToUse;
}
protected async override Task HandleRequirementAsync(AuthorizationHandlerContext context, DefaultAuthorizationRequirement requirement)
{
/*Here, you can quickly check a data source or Web API or etc.
to know the latest date-time of the user's profile modification...
*/
if (_aServiceToUse.GetDateTimeOfLatestUserProfileModication > requirement.DateTimeOfSetup)
{
context.Fail(); /*Because any modifications to user information,
e.g. if the user used another browser or if by Admin modification,
the claims of the user in this session cannot be guaranteed to be reliable.
*/
return;
}
bool shouldSucceed = false; //This should first be false, because context.Succeed(...) has to only be called if the requirement specifically succeeds.
bool shouldFail = false; /*This should first be false, because context.Fail()
doesn't have to be called if there's no security breach.
*/
// You can do anything.
await doAnythingAsync();
/*You can get the user's claims...
ALSO, note that if you have a way to priorly map users or users with certain claims
to particular policies, add those policies as claims of the user for the sake of ease.
BUT policies that require dynamic code (e.g. checking for age range) would have to be
coded in the switch-case below to determine stuff.
*/
var claims = context.User.Claims;
// You can, of course, get the policy that was hit...
var policy = requirement.Policy
//You can use a switch case to determine what policy to deal with here...
switch (policy)
{
case Enumerations.Security.Policy.CanReadResource:
/*Do stuff with the claims and change the
value of shouldSucceed and/or shouldFail.
*/
break;
case Enumerations.Security.Policy.AnotherPolicy:
/*Do stuff with the claims and change the
value of shouldSucceed and/or shouldFail.
*/
break;
// Other policies too.
default:
throw new NotImplementedException();
}
/* Note that the following conditions are
so because failure and success in a requirement handler
are not mutually exclusive. They demand certainty.
*/
if (shouldFail)
{
context.Fail(); /*Check the docs on this method to
see its implications.
*/
}
if (shouldSucceed)
{
context.Succeed(requirement);
}
}
}
Note that the code above can also enable pre-mapping of a user to a policy in your data store. So, when composing claims for the user, you basically retrieve the policies that had been pre-mapped to the user directly or indirectly (e.g. because the user has a certain claim value and that claim value had been identified and mapped to a policy, such that it provides automatic mapping for users who have that claim value too), and enlist the policies as claims, such that in the authorization handler, you can simply check if the user's claims contain requirement.Policy as a Value of a Claim item in their claims. That is for a static way of satisfying a policy requirement, e.g. "First name" requirement is quite static in nature. So, for the example above (which I had forgotten to give example on Authorize attribute in my earlier updates to this answer), using the policy with Authorize attribute is like as follows, where ViewRecord is an enum member:
[Authorize(Policy = nameof(Enumerations.Security.Policy.ViewRecord))]
A dynamic requirement can be about checking age range, etc. and policies that use such requirements cannot be pre-mapped to users.
An example of dynamic policy claims checking (e.g. to check if a user is above 18 years old) is already at the answer given by #blowdart (https://stackoverflow.com/a/31465227/4974715).
PS: I typed this on my phone. Pardon any typos and lack of formatting.

As of this writing I believe this can be accomplished with the IClaimsTransformation interface in asp.net core 2 and above. I just implemented a proof of concept which is sharable enough to post here.
public class PrivilegesToClaimsTransformer : IClaimsTransformation
{
private readonly IPrivilegeProvider privilegeProvider;
public const string DidItClaim = "http://foo.bar/privileges/resolved";
public PrivilegesToClaimsTransformer(IPrivilegeProvider privilegeProvider)
{
this.privilegeProvider = privilegeProvider;
}
public async Task<ClaimsPrincipal> TransformAsync(ClaimsPrincipal principal)
{
if (principal.Identity is ClaimsIdentity claimer)
{
if (claimer.HasClaim(DidItClaim, bool.TrueString))
{
return principal;
}
var privileges = await this.privilegeProvider.GetPrivileges( ... );
claimer.AddClaim(new Claim(DidItClaim, bool.TrueString));
foreach (var privilegeAsRole in privileges)
{
claimer.AddClaim(new Claim(ClaimTypes.Role /*"http://schemas.microsoft.com/ws/2008/06/identity/claims/role" */, privilegeAsRole));
}
}
return principal;
}
}
To use this in your Controller just add an appropriate [Authorize(Roles="whatever")] to your methods.
[HttpGet]
[Route("poc")]
[Authorize(Roles = "plugh,blast")]
public JsonResult PocAuthorization()
{
var result = Json(new
{
when = DateTime.UtcNow,
});
result.StatusCode = (int)HttpStatusCode.OK;
return result;
}
In our case every request includes an Authorization header that is a JWT. This is the prototype and I believe we will do something super close to this in our production system next week.
Future voters, consider the date of writing when you vote. As of today, this works on my machine.™ You will probably want more error handling and logging on your implementation.

Just adding to the great answer from #Shawn. If you are using dotnet 5 you need to update the class to be:
public abstract class AttributeAuthorizationHandler<TRequirement, TAttribute> : AuthorizationHandler<TRequirement> where TRequirement : IAuthorizationRequirement where TAttribute : Attribute
{
protected override Task HandleRequirementAsync(AuthorizationHandlerContext context, TRequirement requirement)
{
var attributes = new List<TAttribute>();
if (context.Resource is HttpContext httpContext)
{
var endPoint = httpContext.GetEndpoint();
var action = endPoint?.Metadata.GetMetadata<ControllerActionDescriptor>();
if(action != null)
{
attributes.AddRange(GetAttributes(action.ControllerTypeInfo.UnderlyingSystemType));
attributes.AddRange(GetAttributes(action.MethodInfo));
}
}
return HandleRequirementAsync(context, requirement, attributes);
}
protected abstract Task HandleRequirementAsync(AuthorizationHandlerContext context, TRequirement requirement, IEnumerable<TAttribute> attributes);
private static IEnumerable<TAttribute> GetAttributes(MemberInfo memberInfo) => memberInfo.GetCustomAttributes(typeof(TAttribute), false).Cast<TAttribute>();
}
Noting the way getting the ControllerActionDescriptor has changed.

I have bearer token and I can read claims.
I use that attribute on controllers and actions
public class CustomAuthorizationAttribute : ActionFilterAttribute
{
public string[] Claims;
public override void OnActionExecuting(ActionExecutingContext context)
{
// check user
var contextUser = context?.HttpContext?.User;
if (contextUser == null)
{
throw new BusinessException("Forbidden");
}
// check roles
var roles = contextUser.FindAll("http://schemas.microsoft.com/ws/2008/06/identity/claims/role").Select(c => c.Value).ToList();
if (!roles.Any(s => Claims.Contains(s)))
{
throw new BusinessException("Forbidden");
}
base.OnActionExecuting(context);
}
}
example
[CustomAuthorization(Claims = new string[]
{
nameof(AuthorizationRole.HR_ADMIN),
nameof(AuthorizationRole.HR_SETTING)
})]
[Route("api/[controller]")]
[ApiController]
public class SomeAdminController : ControllerBase
{
private readonly IMediator _mediator;
public SomeAdminController(IMediator mediator)
{
_mediator = mediator;
}
[HttpGet("list/SomeList")]
public async Task<IActionResult> SomeList()
=> Ok(await _mediator.Send(new SomeListQuery()));
}
That is Roles
public struct AuthorizationRole
{
public static string HR_ADMIN;
public static string HR_SETTING;
}

Here's a simple 5-step guide for how to implement custom role authorization using policies for all you copy and pasters out there :) . I used these docs.
Create a requirement:
public class RoleRequirement : IAuthorizationRequirement
{
public string Role { get; set; }
}
Create a handler:
public class RoleHandler : AuthorizationHandler<RoleRequirement>
{
protected override async Task HandleRequirementAsync(AuthorizationHandlerContext context, RoleRequirement requirement)
{
var requiredRole = requirement.Role;
//custom auth logic
// you can use context to access authenticated user,
// you can use dependecy injection to call custom services
var hasRole = true;
if (hasRole)
{
context.Succeed(requirement);
}
else
{
context.Fail(new AuthorizationFailureReason(this, $"Role {requirement.Role} missing"));
}
}
}
Add the handler in Program.cs:
builder.Services.AddSingleton<IAuthorizationHandler, RoleHandler>();
Add a policy with your role requirement in program.cs:
builder.Services.AddAuthorization(options =>
{
options.AddPolicy("Read", policy => policy.Requirements.Add(new RoleRequirement{Role = "ReadAccess_Custom_System"}));
});
Use your policy:
[Authorize("Read")]
public class ExampleController : ControllerBase
{
}

A lot of people here already told this, but with Policy handlers you can come really far in terms of what you could achieve with the old way in .NET Framework.
I followed a quick writeup from this answer on SO: https://stackoverflow.com/a/61963465/7081176
For me it works flawlessly after making some classes:
The EditUserRequirement:
public class EditUserRequirement : IAuthorizationRequirement
{
public EditUserRequirement()
{
}
}
An abstract handler to make my life easier:
public abstract class AbstractRequirementHandler<T> : IAuthorizationHandler
where T : IAuthorizationRequirement
{
public async Task HandleAsync(AuthorizationHandlerContext context)
{
var pendingRequirements = context.PendingRequirements.ToList();
foreach (var requirement in pendingRequirements)
{
if (requirement is T typedRequirement)
{
await HandleRequirementAsync(context, typedRequirement);
}
}
}
protected abstract Task HandleRequirementAsync(AuthorizationHandlerContext context, T requirement);
}
An implementation of the abstract handler:
public class EditUserRequirementHandler : AbstractRequirementHandler<EditUserRequirement>
{
protected override Task HandleRequirementAsync(AuthorizationHandlerContext context, EditUserRequirement requirement)
{
// If the user is owner of the resource, allow it.
if (IsOwner(context.User, g))
{
context.Succeed(requirement);
}
return Task.CompletedTask;
}
private static bool IsOwner(ClaimsPrincipal user, Guid userIdentifier)
{
return user.GetUserIdentifier() == userIdentifier;
}
}
Registering my handler and requirement:
services.AddSingleton<IAuthorizationHandler, EditUserRequirementHandler>();
services.AddAuthorization(options =>
{
options.AddPolicy(Policies.Policies.EditUser, policy =>
{
policy.Requirements.Add(new EditUserRequirement());
});
});
And then using my Policy in Blazor:
<AuthorizeView Policy="#Policies.EditUser" Resource="#id">
<NotAuthorized>
<Unauthorized />
</NotAuthorized>
<Authorized Context="Auth">
...
</Authorized>
</AuthorizeView>
I hope this is useful for anyone facing this issue.

I have been looking into solving a very similar issue, and settled on creating a custom ActionFilterAttribute (I'm going to call it AuthorizationFilterAttribute) instead of an AuthorizeAttribute to implement the guidance here: https://learn.microsoft.com/en-us/aspnet/core/security/authorization/resourcebased?view=aspnetcore-6.0#challenge-and-forbid-with-an-operational-resource-handler.

For authorization in our app. We had to call a service based on the parameters passed in authorization attribute.
For example, if we want to check if logged in doctor can view patient appointments we will pass "View_Appointment" to custom authorize attribute and check that right in DB service and based on results we will athorize. Here is the code for this scenario:
public class PatientAuthorizeAttribute : TypeFilterAttribute
{
public PatientAuthorizeAttribute(params PatientAccessRights[] right) : base(typeof(AuthFilter)) //PatientAccessRights is an enum
{
Arguments = new object[] { right };
}
private class AuthFilter : IActionFilter
{
PatientAccessRights[] right;
IAuthService authService;
public AuthFilter(IAuthService authService, PatientAccessRights[] right)
{
this.right = right;
this.authService = authService;
}
public void OnActionExecuted(ActionExecutedContext context)
{
}
public void OnActionExecuting(ActionExecutingContext context)
{
var allparameters = context.ActionArguments.Values;
if (allparameters.Count() == 1)
{
var param = allparameters.First();
if (typeof(IPatientRequest).IsAssignableFrom(param.GetType()))
{
IPatientRequest patientRequestInfo = (IPatientRequest)param;
PatientAccessRequest userAccessRequest = new PatientAccessRequest();
userAccessRequest.Rights = right;
userAccessRequest.MemberID = patientRequestInfo.PatientID;
var result = authService.CheckUserPatientAccess(userAccessRequest).Result; //this calls DB service to check from DB
if (result.Status == ReturnType.Failure)
{
//TODO: return apirepsonse
context.Result = new StatusCodeResult((int)System.Net.HttpStatusCode.Forbidden);
}
}
else
{
throw new AppSystemException("PatientAuthorizeAttribute not supported");
}
}
else
{
throw new AppSystemException("PatientAuthorizeAttribute not supported");
}
}
}
}
And on API action we use it like this:
[PatientAuthorize(PatientAccessRights.PATIENT_VIEW_APPOINTMENTS)] //this is enum, we can pass multiple
[HttpPost]
public SomeReturnType ViewAppointments()
{
}

Force reload of ResponseCache in .NET Core 2.1 when request data changes

I am using the following attribute [ResponseCache(Duration = 60)] to cache a specific GET Request which is called a lot on my backend in .NET Core.
Everything is working fine except the cache isn't reloaded when some data in database has changed within the 60 seconds.
Is there a specific directive I have to set to reload/update the cache? link
Example Code Snippet from my Controller:
[HttpGet]
[ResponseCache(Duration = 60)]
public ActionResult<SomeTyp[]> SendDtos()
{
var dtos = _repository.QueryAll();
return Ok(dtos);
}

There is a solution with a usage of "ETag", "If-None-Match" HTTP headers. The idea is using a code which can give us an answer to the question: "Did action response changed?".
This can be done if a controller completely owns particular data lifetime.
Create ITagProvider:
public interface ITagProvider
{
string GetETag(string tagKey);
void InvalidateETag(string tagKey);
}
Create an action filter:
public class ETagActionFilter : IActionFilter
{
private readonly ITagProvider _tagProvider;
public ETagActionFilter(ITagProvider tagProvider)
{
_tagProvider = tagProvider ?? throw new ArgumentNullException(nameof(tagProvider));
}
public void OnActionExecuted(ActionExecutedContext context)
{
if (context.Exception != null)
{
return;
}
var uri = GetActionName(context.ActionDescriptor);
var currentEtag = _tagProvider.GetETag(uri);
if (!string.IsNullOrEmpty(currentEtag))
{
context.HttpContext.Response.Headers.Add("ETag", currentEtag);
}
}
public void OnActionExecuting(ActionExecutingContext context)
{
var uri = GetActionName(context.ActionDescriptor);
var requestedEtag = context.HttpContext.Request.Headers["If-None-Match"];
var currentEtag = _tagProvider.GetETag(uri);
if (requestedEtag.Contains(currentEtag))
{
context.HttpContext.Response.Headers.Add("ETag", currentEtag);
context.Result = new StatusCodeResult(StatusCodes.Status304NotModified);
}
}
private string GetActionName(ActionDescriptor actionDescriptor)
{
return $"{actionDescriptor.RouteValues["controller"]}.{actionDescriptor.RouteValues["action"]}";
}
}
Initialize filter in Startup class:
public void ConfigureServices(IServiceCollection services)
{
// code above
services.AddMvc(options =>
{
options.Filters.Add(typeof(ETagActionFilter));
});
services.AddScoped<ETagActionFilter>();
services.AddSingleton<ITagProvider, TagProvider>();
// code below
}
Use InvalidateETag method somewhere in controllers (in the place where you modifing data):
[HttpPost]
public async Task<ActionResult> Post([FromBody] SomeType data)
{
// TODO: Modify data
// Invalidate tag
var tag = $"{controllerName}.{methodName}"
_tagProvider.InvalidateETag(tag);
return NoContent();
}
This solution may require a change of a client side. If you are using fetch, you can use, for example, the following library: https://github.com/export-mike/f-etag.
P.S. I didn't specify an implementation of the ITagProvider interface, you will need to write your own.
P.P.S. Articles about ETag and caching: https://developers.google.com/web/fundamentals/performance/optimizing-content-efficiency/http-caching, https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/ETag

Why is it so complicated to get the ActionName in ApiController? Easier way?

An MVC controller getting the action name and controller name:
public class AuthorizeController : Controller
{
protected override void OnActionExecuting(ActionExecutingContext filterContext)
{
string actionName = filterContext.ActionDescriptor.ActionName;
string controllerNamespace = filterContext.ActionDescriptor.ControllerDescriptor.ControllerType.FullName;
//..more code
base.OnActionExecuting(filterContext);
}
}
Pretty straight forward.
But when I have an ApiController (System.Web.Http.ApiController), things are more complicated:
Eventually with the help of some rsharper tips I was able to reduce it to a 'few' lines.
private string GetActionName(HttpControllerContext context)
{
var httpRouteDataCollection = context.RouteData.Values.Values;
var httpRouteDataCollection2 = httpRouteDataCollection.FirstOrDefault();
if (!(httpRouteDataCollection2 is IHttpRouteData[] httpRouteData))
{
return null;
}
IHttpRouteData routeData = httpRouteData.FirstOrDefault();
var httpActionDescriptorCollection = routeData?.Route.DataTokens["actions"];
if (!(httpActionDescriptorCollection is HttpActionDescriptor[] httpActionDescriptor))
{
return null;
}
HttpActionDescriptor reflectedHttpActionDescriptor = httpActionDescriptor.FirstOrDefault();
return reflectedHttpActionDescriptor?.ActionName;
}
Can't it be done easier?
Reason for asking this is because currently I am implementing a generic way of determining who can open what action. Some actions are within an WebApi and every time I would need to perform above 'querying'. So this whole conversion things eat up some performance time.
The WHY?
Without going in to much detail, let just assume you have 40 MVC controllers and 20 API controllers with each about 5-10 actions. All of them are stored in the database (loop through them on startup) and can be linked to an Identity role. An admin is able to choose the actions a certain role can perform. After receiving the first answers I might not be clear enough why I would like to create an controller override where I want to do the programming only once.

One of the potential solutions might be an ActionFilterAttribute:
public class ValidateAccessAttribute : ActionFilterAttribute
{
public override void OnActionExecuting(HttpActionContext actionContext)
{
var actionName = actionContext.ActionDescriptor.ActionName;
......
base.OnActionExecuting(actionContext);
}
}
And then on your controllers:
[ValidateAccess]
public async Task<IHttpActionResult> Stuff()
You can even pass arguments to those attributes and have them "smart", like for each action will belong to a certain group and validation of access will be based on a group rather action name. Which can be hard to maintain.
Eg
public class ValidateAccessAttribute2 : ActionFilterAttribute
{
private readonly FunctionalArea _area;
public ValidateAccessAttribute2(FunctionalArea area)
{
_area = area;
}
public override void OnActionExecuting(HttpActionContext actionContext)
{
base.OnActionExecuting(actionContext);
if (!actionContext.Request.Headers.Contains(AuthorizationHeaders.UserNameHeader))
{
actionContext.Response = new HttpResponseMessage(HttpStatusCode.Forbidden);
return;
}
var userName = actionContext.Request.Headers.GetValues("UserNameHeader").First();
if (!UserCanAccessArea(userName, _area))
{
actionContext.Response = new HttpResponseMessage(HttpStatusCode.Forbidden);
return;
}
}
}
[ValidateAccess2(FunctionalArea.AccessToGenericStuff)]
public async Task<IHttpActionResult> Stuff()

Why don't You use ActionContext and ControllerContext?
public class ValuesController : ApiController
{
[HttpGet]
[AllowAnonymous]
public IHttpActionResult Get()
{
var actionName = this.ActionContext.ActionDescriptor.ActionName;
var controlerName = this.ControllerContext.ControllerDescriptor.ControllerName;
return this.Ok();
}
}