接受的答案(https://stackoverflow.com/a/41348219/4974715)实际上是不可维护的或不合适的，因为“CanReadResource”被用作索赔(但本质上应该是现实中的政策，IMO)。答案的方法在它被使用的方式上是不正确的，因为如果一个动作方法需要许多不同的声明设置，那么有了这个答案，你就必须重复写一些像……

[ClaimRequirement(MyClaimTypes.Permission, "CanReadResource")] 
[ClaimRequirement(MyClaimTypes.AnotherPermision, "AnotherClaimVaue")]
//and etc. on a single action.

所以，想象一下这需要多少编码。理想情况下，“CanReadResource”应该是一种策略，它使用许多声明来确定用户是否可以读取资源。

我所做的是将策略创建为枚举，然后循环遍历并设置需求，就像这样……

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.
     */
            }
        }); 

DefaultAuthorizationRequirement类看起来像…

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))] 

动态需求可以是关于检查年龄范围等，使用这种需求的策略不能预先映射到用户。

一个动态策略索赔检查的例子(例如，检查用户是否超过18岁)已经在@blowdart (https://stackoverflow.com/a/31465227/4974715)给出的答案中。

PS:这是我用手机打出来的。请原谅任何拼写错误和缺乏格式。

什么? !

我决定再补充一个简单的答案。B/c我发现大多数答案都有点过度设计。也因为我需要一种授予授权的方法，而不仅仅是否认它。这里的大多数答案都提供了一种“加强”安全性的方法，但我想“放松”它。例如:“如果配置了某些应用程序设置，则允许匿名用户访问”。

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);
        }
    }
}

就是这样。不需要混淆“策略”，“声明”，“处理程序”和其他[哔]

用法:

// GET api/Get/5
[MyAuth]
public ActionResult<string> Get(int id)
{
    return "blahblah";
}

ASP。Net Core团队将使用这里完整记录的新策略设计。新方法背后的基本思想是使用新的[Authorize]属性来指定一个“策略”(例如[Authorize(policy = "YouNeedToBe18ToDoThis")]，其中策略在应用程序的Startup.cs中注册，以执行一些代码块(即确保用户在年龄为18岁或以上时有年龄声明)。

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.

而ASP。Net Core Security团队建议永远不要创建自己的解决方案，在某些情况下，这可能是最谨慎的选择。

下面是一个实现，它使用IAuthorizationFilter提供了一种简单的方式来表达给定控制器或动作的索赔要求:

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();
    }
}

为了在我们的应用程序中进行授权。我们必须根据在授权属性中传递的参数调用服务。

例如，如果我们想检查登录的医生是否可以查看病人的预约，我们将传递“View_Appointment”到自定义授权属性，并在DB服务中检查该权利，并根据结果进行审查。下面是这个场景的代码:

    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");
            }
        }
    }
}

在API操作中，我们像这样使用它:

    [PatientAuthorize(PatientAccessRights.PATIENT_VIEW_APPOINTMENTS)] //this is enum, we can pass multiple
    [HttpPost]
    public SomeReturnType ViewAppointments()
    {

    }

您可以创建自己的AuthorizationHandler，它将在控制器和动作上找到自定义属性，并将它们传递给handlerrequirementasync方法。

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>();
    }
}

然后你可以在你的控制器或动作上使用它的任何自定义属性。例如，添加权限要求。只需创建您的自定义属性。

[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, AllowMultiple = true)]
public class PermissionAttribute : AuthorizeAttribute
{
    public string Name { get; }

    public PermissionAttribute(string name) : base("Permission")
    {
        Name = name;
    }
}

然后创建一个需求，添加到您的策略

public class PermissionAuthorizationRequirement : IAuthorizationRequirement
{
    //Add any custom requirement properties if you have them
}

然后为您的自定义属性创建AuthorizationHandler，继承我们之前创建的AttributeAuthorizationHandler。它将被传递一个IEnumerable，用于handlerrequirementsasync方法中的所有自定义属性，这些属性是由控制器和动作积累而来的。

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
    }
}

最后，在Startup.cs ConfigureServices方法中，将您的自定义AuthorizationHandler添加到服务中，并添加您的Policy。

        services.AddSingleton<IAuthorizationHandler, PermissionAuthorizationHandler>();

        services.AddAuthorization(options =>
        {
            options.AddPolicy("Permission", policyBuilder =>
            {
                policyBuilder.Requirements.Add(new PermissionAuthorizationRequirement());
            });
        });

现在你可以简单地用你的自定义属性装饰你的控制器和动作。

[Permission("AccessCustomers")]
public class CustomersController
{
    [Permission("AddCustomer")]
    IActionResult AddCustomer([FromBody] Customer customer)
    {
        //Add customer
    }
}

我有不记名令牌，我可以阅读索赔。 我在控制器和动作上使用该属性

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);
    }
}

例子

[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()));
}

这就是角色

public struct AuthorizationRole
{
    public static string HR_ADMIN;
    public static string HR_SETTING;
}