AspNetCore3.1_Secutiry源码解析_8_Authorization_授权框架
- 2020 年 3 月 26 日
- 笔记
目录
- AspNetCore3.1_Secutiry源码解析_1_目录
- AspNetCore3.1_Secutiry源码解析_2_Authentication_核心流程
- AspNetCore3.1_Secutiry源码解析_3_Authentication_Cookies
- AspNetCore3.1_Secutiry源码解析_4_Authentication_JwtBear
- AspNetCore3.1_Secutiry源码解析_5_Authentication_OAuth
- AspNetCore3.1_Secutiry源码解析_6_Authentication_OpenIdConnect
- AspNetCore3.1_Secutiry源码解析_7_Authentication_其他
- AspNetCore3.1_Secutiry源码解析_8_Authorization_授权框架
简介
开篇提到过，认证主要解决的是who are you，授权解决的是 are you allowed的问题。各种认证架构可以帮我们知道用户身份（claims），oauth等架构的scope字段能够控制api服务级别的访问权限，但是更加细化和多变的功能授权不是它们的处理范围。
微软的Authorization项目提供了基于策略的灵活的授权框架。
推荐看下面博客了解，我主要学习和梳理源码。
https://www.cnblogs.com/RainingNight/p/authorization-in-asp-net-core.html
依赖注入
注入了以下接口，提供了默认实现
- IAuthorizationService ：授权服务，主干服务
- IAuthorizationPolicyProvider ： 策略提供类
- IAuthorizationHandlerProvider：处理器提供类
- IAuthorizationEvaluator：校验类
- IAuthorizationHandlerContextFactory：授权上下文工厂
- IAuthorizationHandler：授权处理器，这个是注入的集合，一个策略可以有多个授权处理器，依次执行
- 配置类：AuthorizationOptions
微软的命名风格还是比较一致的
Service：服务
Provider：某类的提供者
Evaluator：校验预处理类
Factory：工厂
Handler：处理器
Context：上下文
看源码的过程，不仅可以学习框架背后原理，还可以学习编码风格和设计模式，还是挺有用处的。
/// <summary> /// Adds authorization services to the specified <see cref="IServiceCollection" />. /// </summary> /// <param name="services">The <see cref="IServiceCollection" /> to add services to.</param> /// <returns>The <see cref="IServiceCollection"/> so that additional calls can be chained.</returns> public static IServiceCollection AddAuthorizationCore(this IServiceCollection services) { if (services == null) { throw new ArgumentNullException(nameof(services)); } services.TryAdd(ServiceDescriptor.Transient<IAuthorizationService, DefaultAuthorizationService>()); services.TryAdd(ServiceDescriptor.Transient<IAuthorizationPolicyProvider, DefaultAuthorizationPolicyProvider>()); services.TryAdd(ServiceDescriptor.Transient<IAuthorizationHandlerProvider, DefaultAuthorizationHandlerProvider>()); services.TryAdd(ServiceDescriptor.Transient<IAuthorizationEvaluator, DefaultAuthorizationEvaluator>()); services.TryAdd(ServiceDescriptor.Transient<IAuthorizationHandlerContextFactory, DefaultAuthorizationHandlerContextFactory>()); services.TryAddEnumerable(ServiceDescriptor.Transient<IAuthorizationHandler, PassThroughAuthorizationHandler>()); return services; } /// <summary> /// Adds authorization services to the specified <see cref="IServiceCollection" />. /// </summary> /// <param name="services">The <see cref="IServiceCollection" /> to add services to.</param> /// <param name="configure">An action delegate to configure the provided <see cref="AuthorizationOptions"/>.</param> /// <returns>The <see cref="IServiceCollection"/> so that additional calls can be chained.</returns> public static IServiceCollection AddAuthorizationCore(this IServiceCollection services, Action<AuthorizationOptions> configure) { if (services == null) { throw new ArgumentNullException(nameof(services)); } if (configure != null) { services.Configure(configure); } return services.AddAuthorizationCore(); } 配置类 – AuthorizationOptions
- PolicyMap：策略名称&策略的字典数据
- InvokeHandlersAfterFailure： 授权处理器失败后是否触发下一个处理器，默认true
- DefaultPolicy：默认策略，构造了一个RequireAuthenticatedUser策略，即需要认证用户，不允许匿名访问。现在有点线索了，为什么api一加上[Authorize]，就会校验授权。
- FallbackPolicy：保底策略。没有任何策略的时候会使用保底策略。感觉有点多此一举，不是给了个默认策略吗？
- AddPolicy：添加策略
- GetPolicy：获取策略
/// <summary> /// Provides programmatic configuration used by <see cref="IAuthorizationService"/> and <see cref="IAuthorizationPolicyProvider"/>. /// </summary> public class AuthorizationOptions { private IDictionary<string, AuthorizationPolicy> PolicyMap { get; } = new Dictionary<string, AuthorizationPolicy>(StringComparer.OrdinalIgnoreCase); /// <summary> /// Determines whether authentication handlers should be invoked after a failure. /// Defaults to true. /// </summary> public bool InvokeHandlersAfterFailure { get; set; } = true; /// <summary> /// Gets or sets the default authorization policy. Defaults to require authenticated users. /// </summary> /// <remarks> /// The default policy used when evaluating <see cref="IAuthorizeData"/> with no policy name specified. /// </remarks> public AuthorizationPolicy DefaultPolicy { get; set; } = new AuthorizationPolicyBuilder().RequireAuthenticatedUser().Build(); /// <summary> /// Gets or sets the fallback authorization policy used by <see cref="AuthorizationPolicy.CombineAsync(IAuthorizationPolicyProvider, IEnumerable{IAuthorizeData})"/> /// when no IAuthorizeData have been provided. As a result, the AuthorizationMiddleware uses the fallback policy /// if there are no <see cref="IAuthorizeData"/> instances for a resource. If a resource has any <see cref="IAuthorizeData"/> /// then they are evaluated instead of the fallback policy. By default the fallback policy is null, and usually will have no /// effect unless you have the AuthorizationMiddleware in your pipeline. It is not used in any way by the /// default <see cref="IAuthorizationService"/>. /// </summary> public AuthorizationPolicy FallbackPolicy { get; set; } /// <summary> /// Add an authorization policy with the provided name. /// </summary> /// <param name="name">The name of the policy.</param> /// <param name="policy">The authorization policy.</param> public void AddPolicy(string name, AuthorizationPolicy policy) { if (name == null) { throw new ArgumentNullException(nameof(name)); } if (policy == null) { throw new ArgumentNullException(nameof(policy)); } PolicyMap[name] = policy; } /// <summary> /// Add a policy that is built from a delegate with the provided name. /// </summary> /// <param name="name">The name of the policy.</param> /// <param name="configurePolicy">The delegate that will be used to build the policy.</param> public void AddPolicy(string name, Action<AuthorizationPolicyBuilder> configurePolicy) { if (name == null) { throw new ArgumentNullException(nameof(name)); } if (configurePolicy == null) { throw new ArgumentNullException(nameof(configurePolicy)); } var policyBuilder = new AuthorizationPolicyBuilder(); configurePolicy(policyBuilder); PolicyMap[name] = policyBuilder.Build(); } /// <summary> /// Returns the policy for the specified name, or null if a policy with the name does not exist. /// </summary> /// <param name="name">The name of the policy to return.</param> /// <returns>The policy for the specified name, or null if a policy with the name does not exist.</returns> public AuthorizationPolicy GetPolicy(string name) { if (name == null) { throw new ArgumentNullException(nameof(name)); } return PolicyMap.ContainsKey(name) ? PolicyMap[name] : null; } } IAuthorizationService – 授权服务 – 主干逻辑
接口定义了授权方法，有两个重载，一个是基于requirements校验，一个是基于policyName校验。
Task<AuthorizationResult> AuthorizeAsync(ClaimsPrincipal user, object resource, IEnumerable<IAuthorizationRequirement> requirements); Task<AuthorizationResult> AuthorizeAsync(ClaimsPrincipal user, object resource, string policyName); 看下默认实现DefaultAuthorizationService的处理,逻辑还是比较简单
- 获取策略
- 获取策略的授权条件
- 获取授权上下文
- 获取处理器集合
- 处理器依次执行，结果存入上下文
- 校验器验证上下文
- 返回授权结果类
/// <summary> /// The default implementation of an <see cref="IAuthorizationService"/>. /// </summary> public class DefaultAuthorizationService : IAuthorizationService { private readonly AuthorizationOptions _options; private readonly IAuthorizationHandlerContextFactory _contextFactory; private readonly IAuthorizationHandlerProvider _handlers; private readonly IAuthorizationEvaluator _evaluator; private readonly IAuthorizationPolicyProvider _policyProvider; private readonly ILogger _logger; /// <summary> /// Creates a new instance of <see cref="DefaultAuthorizationService"/>. /// </summary> /// <param name="policyProvider">The <see cref="IAuthorizationPolicyProvider"/> used to provide policies.</param> /// <param name="handlers">The handlers used to fulfill <see cref="IAuthorizationRequirement"/>s.</param> /// <param name="logger">The logger used to log messages, warnings and errors.</param> /// <param name="contextFactory">The <see cref="IAuthorizationHandlerContextFactory"/> used to create the context to handle the authorization.</param> /// <param name="evaluator">The <see cref="IAuthorizationEvaluator"/> used to determine if authorization was successful.</param> /// <param name="options">The <see cref="AuthorizationOptions"/> used.</param> public DefaultAuthorizationService(IAuthorizationPolicyProvider policyProvider, IAuthorizationHandlerProvider handlers, ILogger<DefaultAuthorizationService> logger, IAuthorizationHandlerContextFactory contextFactory, IAuthorizationEvaluator evaluator, IOptions<AuthorizationOptions> options) { if (options == null) { throw new ArgumentNullException(nameof(options)); } if (policyProvider == null) { throw new ArgumentNullException(nameof(policyProvider)); } if (handlers == null) { throw new ArgumentNullException(nameof(handlers)); } if (logger == null) { throw new ArgumentNullException(nameof(logger)); } if (contextFactory == null) { throw new ArgumentNullException(nameof(contextFactory)); } if (evaluator == null) { throw new ArgumentNullException(nameof(evaluator)); } _options = options.Value; _handlers = handlers; _policyProvider = policyProvider; _logger = logger; _evaluator = evaluator; _contextFactory = contextFactory; } /// <summary> /// Checks if a user meets a specific set of requirements for the specified resource. /// </summary> /// <param name="user">The user to evaluate the requirements against.</param> /// <param name="resource">The resource to evaluate the requirements against.</param> /// <param name="requirements">The requirements to evaluate.</param> /// <returns> /// A flag indicating whether authorization has succeeded. /// This value is <value>true</value> when the user fulfills the policy otherwise <value>false</value>. /// </returns> public async Task<AuthorizationResult> AuthorizeAsync(ClaimsPrincipal user, object resource, IEnumerable<IAuthorizationRequirement> requirements) { if (requirements == null) { throw new ArgumentNullException(nameof(requirements)); } var authContext = _contextFactory.CreateContext(requirements, user, resource); var handlers = await _handlers.GetHandlersAsync(authContext); foreach (var handler in handlers) { await handler.HandleAsync(authContext); if (!_options.InvokeHandlersAfterFailure && authContext.HasFailed) { break; } } var result = _evaluator.Evaluate(authContext); if (result.Succeeded) { _logger.UserAuthorizationSucceeded(); } else { _logger.UserAuthorizationFailed(); } return result; } /// <summary> /// Checks if a user meets a specific authorization policy. /// </summary> /// <param name="user">The user to check the policy against.</param> /// <param name="resource">The resource the policy should be checked with.</param> /// <param name="policyName">The name of the policy to check against a specific context.</param> /// <returns> /// A flag indicating whether authorization has succeeded. /// This value is <value>true</value> when the user fulfills the policy otherwise <value>false</value>. /// </returns> public async Task<AuthorizationResult> AuthorizeAsync(ClaimsPrincipal user, object resource, string policyName) { if (policyName == null) { throw new ArgumentNullException(nameof(policyName)); } var policy = await _policyProvider.GetPolicyAsync(policyName); if (policy == null) { throw new InvalidOperationException($"No policy found: {policyName}."); } return await this.AuthorizeAsync(user, resource, policy); } } 默认策略 – 需要认证用户
默认策略添加了校验条件DenyAnonymousAuthorizationRequirement
public AuthorizationPolicyBuilder RequireAuthenticatedUser() { Requirements.Add(new DenyAnonymousAuthorizationRequirement()); return this; } 校验上下文中是否存在认证用户信息，验证通过则在上下文中将校验条件标记为成功。
protected override Task HandleRequirementAsync(AuthorizationHandlerContext context, DenyAnonymousAuthorizationRequirement requirement) { var user = context.User; var userIsAnonymous = user?.Identity == null || !user.Identities.Any(i => i.IsAuthenticated); if (!userIsAnonymous) { context.Succeed(requirement); } return Task.CompletedTask; } 授权时序图
授权项目还是比较好理解的，微软提供了一个基于策略的授权模型，大部门的具体的业务代码还是需要自己去实现的。
classDiagram class AuthorizationPolicy{ Requirements } class Requirement{ } class AuthorizationHandler{ } class IAuthorizationHandler{ +HandleAsync(AuthorizationHandlerContext context) } class IAuthorizationRequirement{ } Requirement–>AuthorizationHandler AuthorizationHandler–>IAuthorizationHandler Requirement–>IAuthorizationHandler Requirement–>IAuthorizationRequirement
中间件去哪了？
开发不需要编写UseAuthorization类似代码，项目中也没发现中间件，甚至找不到 使用AuthorizeAttribute的地方。那么问题来了，框架怎么知道某个方法标记了[Authorize]特性，然后执行校验的呢？
答案是Mvc框架处理的，它读取了节点的[Authorize]和[AllowAnonymous]特性，并触发相应的逻辑。关于Mvc的就不细说了，感兴趣可以翻看源码。
AspNetCoresrcMvcMvc.CoresrcApplicationModelsAuthorizationApplicationModelProvider.cs。
public void OnProvidersExecuting(ApplicationModelProviderContext context) { if (context == null) { throw new ArgumentNullException(nameof(context)); } if (_mvcOptions.EnableEndpointRouting) { // When using endpoint routing, the AuthorizationMiddleware does the work that Auth filters would otherwise perform. // Consequently we do not need to convert authorization attributes to filters. return; } foreach (var controllerModel in context.Result.Controllers) { var controllerModelAuthData = controllerModel.Attributes.OfType<IAuthorizeData>().ToArray(); if (controllerModelAuthData.Length > 0) { controllerModel.Filters.Add(GetFilter(_policyProvider, controllerModelAuthData)); } foreach (var attribute in controllerModel.Attributes.OfType<IAllowAnonymous>()) { controllerModel.Filters.Add(new AllowAnonymousFilter()); } foreach (var actionModel in controllerModel.Actions) { var actionModelAuthData = actionModel.Attributes.OfType<IAuthorizeData>().ToArray(); if (actionModelAuthData.Length > 0) { actionModel.Filters.Add(GetFilter(_policyProvider, actionModelAuthData)); } foreach (var attribute in actionModel.Attributes.OfType<IAllowAnonymous>()) { actionModel.Filters.Add(new AllowAnonymousFilter()); } } } } 
