Fluent validation divide business validation from auth validaton

Fluent validation divide business validation from auth validaton - c#

I'm using ASP, CQRS + MediatR and fluent validation. I want to implement user role validation, but I don't want to mix it with business logic validation. Do you have any idea how to implement this?
I mean a specific validator must be executed for a specific request.
Something tells me the solution lies in IEnumerable< IValidator>
{
private readonly IEnumerable<IValidator<TRequest>> _validators;
public ValidationBehavior(IEnumerable<IValidator<TRequest>> validators) => _validators = validators;
public async Task<TResponse> Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate<TResponse> next)
{
if (_validators.Any())
{
var context = new ValidationContext<TRequest>(request);
var validationResults = await Task.WhenAll(_validators.Select(v => v.ValidateAsync(context, cancellationToken)));
var failures = validationResults.SelectMany(r => r.Errors).Where(f => f != null).ToArray();
if (failures.Any())
{
var errors = failures
.Select(x => new Error(x.ErrorMessage, x.ErrorCode))
.ToArray();
throw new ValidationException(errors);
}
}
return await next();
}
}

I see your concern, I also found myself in this situation. I wanted to separate my validators from handlers while also keeping them in the domain/business project. Also I didn't want to throw exceptions just to handle bad request or any other custom business exception.
You have the right idea by
I mean a specific validator must be executed for a specific request
For this, you need to set up a mediator pipeline, so for every Command you can find the appropriate the appropriate validator, validate and decide whether to execute the command or return a failed result.
First, create an interface(although not necessary but it is how I did it) of ICommand like this:
public interface ICommand<TResponse>: IRequest<TResponse>
{
}
And, ICommandHandler like:
public interface ICommandHandler<in TCommand, TResponse>: IRequestHandler<TCommand, TResponse>
where TCommand : ICommand<TResponse>
{
}
This way we can only apply validation to commands. Instead of iheriting IRequest<MyOutputDTO> and IRequestHandler<MyCommand, MyOutputDTO> you inherit from ICommand and ICommandHandler.
Now create a ValidationBehaviour for the mediator as we agreed before.
public class ValidationBehaviour<TRequest, TResponse> : IPipelineBehavior<TRequest, TResponse>
where TRequest : class, ICommand<TResponse>
{
private readonly IEnumerable<IValidator<TRequest>> _validators;
public ValidationBehaviour(IEnumerable<IValidator<TRequest>> validators) => _validators = validators;
public async Task<TResponse> Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate<TResponse> next)
{
if (!_validators.Any())
return await next();
var validationContext = new ValidationContext<TRequest>(request);
var errors = (await Task.WhenAll(_validators
.Select(async x => await x.ValidateAsync(validationContext))))
.SelectMany(x => x.Errors)
.Where(x => x != null)
.Select(x => x.CustomState)
.Cast<TResponse>();
//TResponse should be of type Result<T>
if (errors.Any())
return errors.First();
try
{
return await next();
}
catch(Exception e)
{
//most likely internal server error
//better retain error as an inner exception for debugging
//but also return that an error occurred
return Result<TResponse>.Failure(new InternalServerException(e));
}
}
}
This code simply, excepts all the validators in the constructor, because you register all your validator from assembly for your DI container to inject them.
It waits for all validations to validate async(because my validations mostly require calls to db itself such as getting user roles etc).
Then check for errors and return the error(here I have created a DTO to wrap my error and value to get consistent results).
If there were no errors simply let the handler do it's work return await next();
Now you have to register this pipeline behavior and all the validators.
I use autofac so I can do it easily by
builder
.RegisterAssemblyTypes(_assemblies.ToArray())
.AsClosedTypesOf(typeof(IValidator<>))
.AsImplementedInterfaces();
var mediatrOpenTypes = new[]
{
typeof(IRequestHandler<,>),
typeof(IRequestExceptionHandler<,,>),
typeof(IRequestExceptionAction<,>),
typeof(INotificationHandler<>),
typeof(IPipelineBehavior<,>)
};
foreach (var mediatrOpenType in mediatrOpenTypes)
{
builder
.RegisterAssemblyTypes(_assemblies.ToArray())
.AsClosedTypesOf(mediatrOpenType)
.AsImplementedInterfaces();
}
If you use Microsoft DI, you can:
services.AddMediatR(typeof(Application.AssemblyReference).Assembly);
services.AddTransient(typeof(IPipelineBehavior<,>), typeof(ValidationBehavior<,>));
services.AddValidatorsFromAssembly(typeof(Application.AssemblyReference).Assembly); //to add validators
Example usage:
My generic DTO Wrapper
public class Result<T>: IResult<T>
{
public Result(T? value, bool isSuccess, Exception? error)
{
IsSuccess = isSuccess;
Value = value;
Error = error;
}
public bool IsSuccess { get; set; }
public T? Value { get; set; }
public Exception? Error { get; set; }
public static Result<T> Success(T value) => new (value, true, null);
public static Result<T> Failure(Exception error) => new (default, false, error);
}
A sample Command:
public record CreateNewRecordCommand(int UserId, string record) : ICommand<Result<bool>>;
Validator for it:
public class CreateNewRecordCommandValidator : AbstractValidator<CreateNewRecordCommand>
{
public CreateNewVoucherCommandValidator(DbContext _context, IMediator mediator) //will be injected by out DI container
{
RuleFor(x => x.record)
.NotEmpty()
.WithState(x => Result<bool>.Failure(new Exception("Empty record")));
//.WithName("record") if your validation a property in array or something and can't find appropriate property name
RuleFor(x => x.UserId)
.MustAsync(async(id, cToken) =>
{
//var roles = await mediator.send(new GetUserRolesQuery(id, cToken));
//var roles = (await context.Set<User>.FirstAsync(user => user.id == id)).roles
//return roles.Contains(MyRolesEnum.CanCreateRecordRole);
}
)
.WithState(x => Result<bool>.Failure(new MyCustomForbiddenRequestException(id)))
}
}
This way you always get a result object, you can check if error is null or !IsSuccess and then create a custom HandleResult(result) method in your Controller base which can switch on the exception to return BadReuqestObjectResult(result) or ForbiddenObjectResult(result).
If you prefer to throw, catch and handle the exceptions in the pipeline or you wan't non-async implementation, read this https://code-maze.com/cqrs-mediatr-fluentvalidation/
This way all your validations are very far from your handler while maintaining consistent results.

I think that your initial approach its right. When you say that you want to keep the auth validations apart from the other business validation, do you mean like returning a http error like 403 and 401 right?
If thats the case try marking the auth validations with and interface to identify they, and do not run all the validations at once. Search first in the collection for a validation with that interface, and if it fails send a custom exception that you can identity in a IActionFilter to set the wanted result. This code does not do that exactly but you can make an idea.
public class HttpResponseExceptionFilter : IActionFilter, IOrderedFilter
{
private ISystemLogger _logger;
public HttpResponseExceptionFilter()
{
}
public int Order { get; } = int.MaxValue - 10;
public void OnActionExecuting(ActionExecutingContext context) { }
public void OnActionExecuted(ActionExecutedContext context)
{
if (context.Exception is PipelineValidationException exception)
{
context.Result = new ObjectResult(new Response(false, exception.ValidationErrors.FirstOrDefault()?.ErrorMessage ?? I18n.UnknownError));
context.ExceptionHandled = true;
}
else if (context.Exception != null)
{
_logger ??= (ISystemLogger)context.HttpContext.RequestServices.GetService(typeof(ISystemLogger));
_logger?.LogException(this, context.Exception, methodName: context.HttpContext.Request.Method);
context.Result = new ObjectResult(new Response(false, I18n.UnknownError));
context.ExceptionHandled = true;
}
}
}

Related

Custom Authorize attribute [CustomAuthorize] not working with Blazor asp.net core 5 [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()
{
}

How can I wrap failed model validation result of an ASP.NET Core 5 Web API controller action into another class and return response as OK

I have ASP.NET Web API controller with some actions (methods). Let's say something like this:
[HttpPost]
public async Task<ActionResult> SavePerson([FromBody]PersonDto person)
{
await _mediatr.Send(new SavePerson.Command(person));
return Ok();
}
and the PersonDto looks something like this:
public record PersonDto([Required, MinLength(3)]string Name, int? Age);
When I call my Web API action 'SavePerson' with invalid person data (Name.Length < 3 and etc...), ASP.NET Core model binding validation interrupts the execution and returns 400 (Bad Request) as it should. When I pass valid person data, it works fine.
My questions are:
How can I catch this model binding validation result (400 Bad Request) and transform it into different format, so our front-end developers will be happy?
Should I validate my DTOs (PersonDto) in Web API layer or it's better to validate it in MediatR command handler? I'm trying to adhere Uncle Bob's Clean Architecture. I have Domain, Application, Infrastructure, Web API. And my MediatR CQRS handlers are placed in the Application layer.

Automatic 400 bad request responses is enabled by default. To disable it use the following code in Startup ConfigureServices method:
services.Configure<ApiBehaviorOptions>(options =>
{
options.SuppressModelStateInvalidFilter = true;
});
Then you can handle invalid model states manually like this:
[HttpPost]
public async Task<ActionResult> SavePerson([FromBody]PersonDto person)
{
if(!ModelState.IsValid)
return BadRequest(ModelState);// or what ever you want
await _mediatr.Send(new SavePerson.Command(person));
return Ok();
}

You can use Jason Taylor's Clean Architecture approach. Instead of using attribute validation, use FluentValidation:
public class CreatePersonCommandValidator : AbstractValidator<SavePerson.Command>
{
public CreatePersonCommandValidator()
{
RuleFor(v => v.Title)
.NotEmpty().WithMessage("Title is required.")
.MinimujLength(200).WithMessage("Title at least should have 3 characters.");
}
}
Use MediatR behavior to perform validation and translate errors into validation exception:
public class ValidationBehaviour<TRequest, TResponse> : IPipelineBehavior<TRequest, TResponse>
where TRequest : IRequest<TResponse>
{
private readonly IEnumerable<IValidator<TRequest>> _validators;
public ValidationBehaviour(IEnumerable<IValidator<TRequest>> validators)
{
_validators = validators;
}
public async Task<TResponse> Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate<TResponse> next)
{
if (_validators.Any())
{
var context = new ValidationContext<TRequest>(request);
var validationResults = await Task.WhenAll(_validators.Select(v => v.ValidateAsync(context, cancellationToken)));
var failures = validationResults.SelectMany(r => r.Errors).Where(f => f != null).ToList();
if (failures.Count != 0)
throw new ValidationException(failures);
}
return await next();
}
}
Validation exception:
public class ValidationException : Exception
{
public ValidationException()
: base("One or more validation failures have occurred.")
{
Errors = new Dictionary<string, string[]>();
}
public ValidationException(IEnumerable<ValidationFailure> failures)
: this()
{
Errors = failures
.GroupBy(e => e.PropertyName, e => e.ErrorMessage)
.ToDictionary(failureGroup => failureGroup.Key, failureGroup => failureGroup.ToArray());
}
public IDictionary<string, string[]> Errors { get; }
}
And finally, implement an exception filter or exception handling middleware to catch that exception and return desired response:
public class ApiExceptionFilterAttribute : ExceptionFilterAttribute
{
private readonly IDictionary<Type, Action<ExceptionContext>> _exceptionHandlers;
public ApiExceptionFilterAttribute()
{
// Register known exception types and handlers.
_exceptionHandlers = new Dictionary<Type, Action<ExceptionContext>>
{
{ typeof(ValidationException), HandleValidationException }
};
}
public override void OnException(ExceptionContext context)
{
HandleException(context);
base.OnException(context);
}
private void HandleException(ExceptionContext context)
{
Type type = context.Exception.GetType();
if (_exceptionHandlers.ContainsKey(type))
{
_exceptionHandlers[type].Invoke(context);
return;
}
if (!context.ModelState.IsValid)
{
HandleInvalidModelStateException(context);
return;
}
HandleUnknownException(context);
}
private void HandleValidationException(ExceptionContext context)
{
var exception = context.Exception as ValidationException;
//var details = new ValidationProblemDetails(exception.Errors)
//{
//Type = "https://tools.ietf.org/html/rfc7231#section-6.5.1"
//};
context.Result = Returns your response type //new BadRequestObjectResult(details);
context.ExceptionHandled = true;
}
}

You can perform ModelState.isValid() in the biginig of your Api method and return a BadRequestResult() if the model is invalid. You can can return the validation errors along with BadRequestResult.
You need to get validation errors from model state and fill your custom error object. This way your customers can see more meaningful errors.

How to use custom Authorize attribute in Asp.Net Core? [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()
{
}

How to make a custom Authorize attribute in ASP.NET Core? [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()
{
}

How do you create a custom AuthorizeAttribute in ASP.NET Core?

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()
{
}

We Keep Coding

C# (C-Sharp) is a programming language developed by Microsoft that runs on the .NET Framework.

Fluent validation divide business validation from auth validaton - c#

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