缘起
标准的rabc, 权限需要支持动态配置，spring security默认是在代码里约定好权限，真实的业务场景通常需要可以支持动态配置角色访问权限，即在运行时去配置url对应的访问角色。
基于spring security，如何实现这个需求呢？
最简单的方法就是自定义一个filter去完成权限判断，但这脱离了spring security框架，如何基于spring security优雅的实现呢？
spring security 授权回顾
spring security 通过filterchainproxy作为注册到web的filter，filterchainproxy里面一次包含了内置的多个过滤器，我们首先需要了解spring security内置的各种filter：
| alias | filter class | namespace element or attribute |
|---|---|---|
| channel_filter | channelprocessingfilter | http/intercept-url@requires-channel |
| security_context_filter | securitycontextpersistencefilter | http |
| concurrent_session_filter | concurrentsessionfilter | session-management/concurrency-control |
| headers_filter | headerwriterfilter | http/headers |
| csrf_filter | csrffilter | http/csrf |
| logout_filter | logoutfilter | http/logout |
| x509_filter | x509authenticationfilter | http/x509 |
| pre_auth_filter | abstractpreauthenticatedprocessingfilter subclasses | n/a |
| cas_filter | casauthenticationfilter | n/a |
| form_login_filter | usernamepasswordauthenticationfilter | http/form-login |
| basic_auth_filter | basicauthenticationfilter | http/http-basic |
| servlet_api_support_filter | securitycontextholderawarerequestfilter | http/@servlet-api-provision |
| jaas_api_support_filter | jaasapiintegrationfilter | http/@jaas-api-provision |
| remember_me_filter | remembermeauthenticationfilter | http/remember-me |
| anonymous_filter | anonymousauthenticationfilter | http/anonymous |
| session_management_filter | sessionmanagementfilter | session-management |
| exception_translation_filter | exceptiontranslationfilter | http |
| filter_security_interceptor | filtersecurityinterceptor | http |
| switch_user_filter | switchuserfilter | n/a |
最重要的是filtersecurityinterceptor，该过滤器实现了主要的鉴权逻辑，最核心的代码在这里：
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protected interceptorstatustoken beforeinvocation(object object) { // 获取访问url所需权限 collection<configattribute> attributes = this.obtainsecuritymetadatasource() .getattributes(object); authentication authenticated = authenticateifrequired(); // 通过accessdecisionmanager鉴权 try { this.accessdecisionmanager.decide(authenticated, object, attributes); } catch (accessdeniedexception accessdeniedexception) { publishevent(new authorizationfailureevent(object, attributes, authenticated, accessdeniedexception)); throw accessdeniedexception; } if (debug) { logger.debug("authorization successful"); } if (publishauthorizationsuccess) { publishevent(new authorizedevent(object, attributes, authenticated)); } // attempt to run as a different user authentication runas = this.runasmanager.buildrunas(authenticated, object, attributes); if (runas == null) { if (debug) { logger.debug("runasmanager did not change authentication object"); } // no further work post-invocation return new interceptorstatustoken(securitycontextholder.getcontext(), false, attributes, object); } else { if (debug) { logger.debug("switching to runas authentication: " + runas); } securitycontext origctx = securitycontextholder.getcontext(); securitycontextholder.setcontext(securitycontextholder.createemptycontext()); securitycontextholder.getcontext().setauthentication(runas); // need to revert to token.authenticated post-invocation return new interceptorstatustoken(origctx, true, attributes, object); } } |
从上面可以看出，要实现动态鉴权，可以从两方面着手：
- 自定义securitymetadatasource，实现从数据库加载configattribute
- 另外就是可以自定义accessdecisionmanager，官方的unanimousbased其实足够使用，并且他是基于accessdecisionvoter来实现权限认证的，因此我们只需要自定义一个accessdecisionvoter就可以了
下面来看分别如何实现。
自定义accessdecisionmanager
官方的三个accessdecisionmanager都是基于accessdecisionvoter来实现权限认证的，因此我们只需要自定义一个accessdecisionvoter就可以了。
自定义主要是实现accessdecisionvoter接口，我们可以仿照官方的rolevoter实现一个：
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public class rolebasedvoter implements accessdecisionvoter<object> { @override public boolean supports(configattribute attribute) { return true; } @override public int vote(authentication authentication, object object, collection<configattribute> attributes) { if(authentication == null) { return access_denied; } int result = access_abstain; collection<? extends grantedauthority> authorities = extractauthorities(authentication); for (configattribute attribute : attributes) { if(attribute.getattribute()==null){ continue; } if (this.supports(attribute)) { result = access_denied; // attempt to find a matching granted authority for (grantedauthority authority : authorities) { if (attribute.getattribute().equals(authority.getauthority())) { return access_granted; } } } } return result; } collection<? extends grantedauthority> extractauthorities( authentication authentication) { return authentication.getauthorities(); } @override public boolean supports(class clazz) { return true; }} |
如何加入动态权限呢？
vote(authentication authentication, object object, collection<configattribute> attributes)里的object object的类型是filterinvocation，可以通过getrequesturl获取当前请求的url:
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filterinvocation fi = (filterinvocation) object;string url = fi.getrequesturl(); |
因此这里扩展空间就大了，可以从db动态加载，然后判断url的configattribute就可以了。
如何使用这个rolebasedvoter呢？在configure里使用accessdecisionmanager方法自定义，我们还是使用官方的unanimousbased，然后将自定义的rolebasedvoter加入即可。
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@enablewebsecurity@enableglobalmethodsecurity(prepostenabled = true, securedenabled = true)public class securityconfiguration extends websecurityconfigureradapter { @override protected void configure(httpsecurity http) throws exception { http .addfilterbefore(corsfilter, usernamepasswordauthenticationfilter.class) .exceptionhandling() .authenticationentrypoint(problemsupport) .accessdeniedhandler(problemsupport) .and() .csrf() .disable() .headers() .frameoptions() .disable() .and() .sessionmanagement() .sessioncreationpolicy(sessioncreationpolicy.stateless) .and() .authorizerequests() // 自定义accessdecisionmanager .accessdecisionmanager(accessdecisionmanager()) .and() .apply(securityconfigureradapter()); } @bean public accessdecisionmanager accessdecisionmanager() { list<accessdecisionvoter<? extends object>> decisionvoters = arrays.aslist( new webexpressionvoter(), // new rolevoter(), new rolebasedvoter(), new authenticatedvoter()); return new unanimousbased(decisionvoters); } |
自定义securitymetadatasource
自定义filterinvocationsecuritymetadatasource只要实现接口即可，在接口里从db动态加载规则。
为了复用代码里的定义，我们可以将代码里生成的securitymetadatasource带上，在构造函数里传入默认的filterinvocationsecuritymetadatasource。
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public class appfilterinvocationsecuritymetadatasource implements org.springframework.security.web.access.intercept.filterinvocationsecuritymetadatasource { private filterinvocationsecuritymetadatasource supermetadatasource; @override public collection<configattribute> getallconfigattributes() { return null; } public appfilterinvocationsecuritymetadatasource(filterinvocationsecuritymetadatasource expressionbasedfilterinvocationsecuritymetadatasource){ this.supermetadatasource = expressionbasedfilterinvocationsecuritymetadatasource; // todo 从数据库加载权限配置 } private final antpathmatcher antpathmatcher = new antpathmatcher(); // 这里的需要从db加载 private final map<string,string> urlrolemap = new hashmap<string,string>(){{ put("/open/**","role_anonymous"); put("/health","role_anonymous"); put("/restart","role_admin"); put("/demo","role_user"); }}; @override public collection<configattribute> getattributes(object object) throws illegalargumentexception { filterinvocation fi = (filterinvocation) object; string url = fi.getrequesturl(); for(map.entry<string,string> entry:urlrolemap.entryset()){ if(antpathmatcher.match(entry.getkey(),url)){ return securityconfig.createlist(entry.getvalue()); } } // 返回代码定义的默认配置 return supermetadatasource.getattributes(object); } @override public boolean supports(class<?> clazz) { return filterinvocation.class.isassignablefrom(clazz); }} |
怎么使用？和accessdecisionmanager不一样，expressionurlauthorizationconfigurer 并没有提供set方法设置filtersecurityinterceptor的filterinvocationsecuritymetadatasource，how to do?
发现一个扩展方法withobjectpostprocessor，通过该方法自定义一个处理filtersecurityinterceptor类型的objectpostprocessor就可以修改filtersecurityinterceptor。
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@enablewebsecurity@enableglobalmethodsecurity(prepostenabled = true, securedenabled = true)public class securityconfiguration extends websecurityconfigureradapter { @override protected void configure(httpsecurity http) throws exception { http .addfilterbefore(corsfilter, usernamepasswordauthenticationfilter.class) .exceptionhandling() .authenticationentrypoint(problemsupport) .accessdeniedhandler(problemsupport) .and() .csrf() .disable() .headers() .frameoptions() .disable() .and() .sessionmanagement() .sessioncreationpolicy(sessioncreationpolicy.stateless) .and() .authorizerequests() // 自定义filterinvocationsecuritymetadatasource .withobjectpostprocessor(new objectpostprocessor<filtersecurityinterceptor>() { @override public <o extends filtersecurityinterceptor> o postprocess( o fsi) { fsi.setsecuritymetadatasource(mysecuritymetadatasource(fsi.getsecuritymetadatasource())); return fsi; } }) .and() .apply(securityconfigureradapter()); } @bean public appfilterinvocationsecuritymetadatasource mysecuritymetadatasource(filterinvocationsecuritymetadatasource filterinvocationsecuritymetadatasource) { appfilterinvocationsecuritymetadatasource securitymetadatasource = new appfilterinvocationsecuritymetadatasource(filterinvocationsecuritymetadatasource); return securitymetadatasource;} |
小结
本文介绍了两种基于spring security实现动态权限的方法，一是自定义accessdecisionmanager，二是自定义filterinvocationsecuritymetadatasource。实际项目里可以根据需要灵活选择。
延伸阅读:
总结
以上就是这篇文章的全部内容了，希望本文的内容对大家的学习或者工作具有一定的参考学习价值，如果有疑问大家可以留言交流，谢谢大家对服务器之家的支持。
原文链接：http://www.cnblogs.com/xiaoqi/p/spring-security-rabc.html
