单点登录系统使用Spring Security的权限功能

背景

在配置中心增加权限功能

• 目前配置中心已经包含了单点登录功能，可以通过统一页面进行登录，登录完会将用户写入用户表
• RBAC的用户、角色、权限表CRUD、授权等都已经完成
• 希望不用用户再次登录，就可以使用SpringSecurity的权限控制

Spring Security

Spring Security最主要的两个功能：认证和授权

功能	解决的问题	Spring Security中主要类
认证（Authentication）	你是谁	AuthenticationManager
授权（Authorization）	你可以做什么	AuthorizationManager

实现

在这先简单了解一下Spring Security的架构是怎样的，如何可以认证和授权的

过滤器大家应该都了解，这属于Servlet的范畴，Servlet 过滤器可以动态地拦截请求和响应，以变换或使用包含在请求或响应中的信息

DelegatingFilterProxy是一个属于Spring Security的过滤器

通过这个过滤器，Spring Security就可以从Request中获取URL来判断是不是需要认证才能访问，是不是得拥有特定的权限才能访问。

已经有了单点登录页面，Spring Security怎么登录，不登录可以拿到权限吗

Spring Security官方文档-授权架构中这样说，GrantedAuthority（也就是拥有的权限）被AuthenticationManager写入Authentication对象，后而被AuthorizationManager用来做权限认证

The GrantedAuthority objects are inserted into the Authentication object by the AuthenticationManager and are later read by either the AuthorizationManager when making authorization decisions.

为了解决我们的问题，即使我只想用权限认证功能，也得造出一个Authentication，先看下这个对象：

Authentication

Authentication包含三个字段：

• principal，代表用户
• credentials，用户密码
• authorities，拥有的权限

有两个作用:

• AuthenticationManager的入参，仅仅是用来存用户的信息，准备去认证
• AuthenticationManager的出参，已经认证的用户信息，可以从SecurityContext获取

SecurityContext和SecurityContextHolder用来存储Authentication， 通常是用了线程全局变量ThreadLocal, 也就是认证完成把Authentication放入SecurityContext，后续在整个同线程流程中都可以获取认证信息，也方便了认证

继续分析

看到这可以得到，要实现不登录的权限认证，只需要手动造一个Authentication，然后放入SecurityContext就可以了，先尝试一下，大概流程是这样，在每个请求上

1. 获取sso登录的用户
2. 读取用户、角色、权限写入Authentication
3. 将Authentication写入SecurityContext
4. 请求完毕时将SecurityContext清空，因为是ThreadLocal的，不然可能会被别的用户用到
5. 同时Spring Security的配置中是对所有的url都允许访问的

加了一个过滤器，代码如下：

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

@WebFilter( urlPatterns = "/*", filterName = "reqResFilter" )
public class ReqResFilter implements Filter{

	@Autowired
	private SSOUtils ssoUtils;
	@Autowired
	private UserManager userManager;
	@Autowired
	private RoleManager roleManager;

	@Override
	public void init( FilterConfig filterConfig ) throws ServletException{

	}

	@Override
	public void doFilter( ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain )
			throws IOException, ServletException{
		setAuthentication(servletRequest);
		filterChain.doFilter( servletRequest, servletResponse );
		clearAuthentication();
	}

	@Override
	public void destroy(){

	}

	private void setAuthentication( ServletRequest request ){

		Map<String, String> data;
		try{
			data = ssoUtils.getLoginData( ( HttpServletRequest )request );
		}
		catch( Exception e ){
			data = new HashMap<>();
			data.put( "name", "visitor" );
		}
		String username = data.get( "name" );
		if( username != null ){
			userManager.findAndInsert( username );
		}
		List<Role> userRole = userManager.findUserRole( username );
		List<Long> roleIds = userRole.stream().map( Role::getId ).collect( Collectors.toList() );
		List<Permission> rolePermission = roleManager.findRolePermission( roleIds );
		List<SimpleGrantedAuthority> authorities = rolePermission.stream().map( one -> new SimpleGrantedAuthority( one.getName() ) ).collect(
				Collectors.toList() );

		UsernamePasswordAuthenticationToken authenticationToken = new UsernamePasswordAuthenticationToken( username, "", authorities );
		SecurityContextHolder.getContext().setAuthentication( authenticationToken );
	}

	private void clearAuthentication(){

		SecurityContextHolder.clearContext();
	}
}

从日志可以看出，Principal: visitor，当访问未授权的接口被拒绝了

16:04:07.429 [http-nio-8081-exec-9] DEBUG org.springframework.security.access.intercept.aopalliance.MethodSecurityInterceptor - Previously Authenticated: org.springframework.security.authentication.UsernamePasswordAuthenticationToken@cc4c6ea0: Principal: visitor; Credentials: [PROTECTED]; Authenticated: true; Details: null; Granted Authorities: CHANGE_USER_ROLE, CHANGE_ROLE_PERMISSION, ROLE_ADD
...
org.springframework.security.access.AccessDeniedException: 不允许访问

结论

不登录是可以使用Spring Security的权限，从功能上是没有问题的，但存在一些别的问题

• 性能问题，每个请求都需要请求用户角色权限数据库，当然可以利用缓存优化
• 我们写的过滤器其实也是Spring Security做的事，除此之外，它做了更多的事，比如结合HttpSession, Remember me这些功能

我们可以采取另外一种做法，对用户来说只登录一次就行，我们仍然是可以手动用代码再去登录一次Spring Security的

如何手动登录Spring Security

How to login user from java code in Spring Security? 从这篇文章从可以看到，只要通过以下代码即可

	private void loginInSpringSecurity( String username, String password ){

		UsernamePasswordAuthenticationToken loginToken = new UsernamePasswordAuthenticationToken( username, password );
		Authentication authenticatedUser = authenticationManager.authenticate( loginToken );
		SecurityContextHolder.getContext().setAuthentication( authenticatedUser );
	}

和上面我们直接拿已经认证过的用户对比，这段代码让Spring Security来执行认证步骤，不过需要配置额外的AuthenticationManager和UserDetailsServiceImpl，这两个配置只是AuthenticationManager的一种实现，和上面的流程区别不大，目的就是为了拿到用户的信息和权限进行认证

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.security.core.GrantedAuthority;
import org.springframework.security.core.authority.SimpleGrantedAuthority;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.security.core.userdetails.UserDetailsService;
import org.springframework.security.core.userdetails.UsernameNotFoundException;
import org.springframework.stereotype.Service;

import java.util.List;
import java.util.stream.Collectors;

@Service
public class UserDetailsServiceImpl implements UserDetailsService{

	private static final Logger logger = LoggerFactory.getLogger( UserDetailsServiceImpl.class );

	@Autowired
	private UserManager userManager;

	@Autowired
	private RoleManager roleManager;

	@Override
	public UserDetails loadUserByUsername( String username ) throws UsernameNotFoundException{

		User user = userManager.findByName( username );
		if( user == null ){
			logger.info( "登录用户[{}]没注册!", username );
			throw new UsernameNotFoundException( "登录用户[" + username + "]没注册!" );
		}
		return new org.springframework.security.core.userdetails.User( user.getUsername(), "", getAuthority( username ) );
	}

	private List<? extends GrantedAuthority> getAuthority( String username ){

		List<Role> userRole = userManager.findUserRole( username );
		List<Long> roleIds = userRole.stream().map( Role::getId ).collect( Collectors.toList() );
		List<Permission> rolePermission = roleManager.findRolePermission( roleIds );
		return rolePermission.stream().map( one -> new SimpleGrantedAuthority( one.getName() ) ).collect( Collectors.toList() );
	}
}

	@Override
	@Bean
	public AuthenticationManager authenticationManagerBean() throws Exception{

		DaoAuthenticationProvider daoAuthenticationProvider = new DaoAuthenticationProvider();
		daoAuthenticationProvider.setUserDetailsService( userDetailsService );
		daoAuthenticationProvider.setPasswordEncoder( NoOpPasswordEncoder.getInstance() );
		return new ProviderManager( daoAuthenticationProvider );
	}

结论

通过这样的方式，同样实现了权限认证，同时Spring Security会将用户信息和权限缓存到了Session中，这样就不用每次去数据库获取

总结

可以通过两种方式来实现不登录使用SpringSecurity的权限功能

1. 手动组装认证过的Authentication直接写到SecurityContext，需要我们自己使用过滤器控制写入和清除
2. 手动组装未认证过的Authentication，并交给Spring Security认证，并写入SecurityContext

附

Spring Security是如何配置的，因为只使用权限功能，所有允许所有的路径访问（我们的单点登录会限制接口的访问）

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.security.authentication.AuthenticationManager;
import org.springframework.security.authentication.ProviderManager;
import org.springframework.security.authentication.dao.DaoAuthenticationProvider;
import org.springframework.security.config.annotation.method.configuration.EnableGlobalMethodSecurity;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;
import org.springframework.security.core.userdetails.UserDetailsService;
import org.springframework.security.crypto.password.NoOpPasswordEncoder;
import org.springframework.web.cors.CorsConfiguration;
import org.springframework.web.cors.CorsConfigurationSource;
import org.springframework.web.cors.UrlBasedCorsConfigurationSource;

import java.util.Arrays;
import java.util.Collections;

@Configuration
@EnableWebSecurity
@EnableGlobalMethodSecurity(prePostEnabled = true)
public class WebSecurityConfig extends WebSecurityConfigurerAdapter{

	@Autowired
	private UserDetailsService userDetailsService;

	@Override
	protected void configure( HttpSecurity http ) throws Exception{

		http
				.cors()
				.and()
				.csrf()
				.disable()
				.sessionManagement()
				.and()
				.authorizeRequests()
				.anyRequest()
				.permitAll()
				.and()
				.exceptionHandling()
				.accessDeniedHandler( new SimpleAccessDeniedHandler() );
	}

	@Override
	@Bean
	public AuthenticationManager authenticationManagerBean() throws Exception{

		DaoAuthenticationProvider daoAuthenticationProvider = new DaoAuthenticationProvider();
		daoAuthenticationProvider.setUserDetailsService( userDetailsService );
		daoAuthenticationProvider.setPasswordEncoder( NoOpPasswordEncoder.getInstance() );
		return new ProviderManager( daoAuthenticationProvider );
	}

	@Bean
	public CorsConfigurationSource corsConfigurationSource(){

		CorsConfiguration configuration = new CorsConfiguration();
		configuration.setAllowedOrigins( Collections.singletonList( "*" ) );
		configuration.setAllowedMethods( Arrays.asList( "GET", "HEAD", "POST", "PUT", "DELETE", "OPTIONS" ) );
		configuration.setAllowCredentials( true );
		configuration.setAllowedHeaders( Collections.singletonList( "*" ) );
		configuration.setMaxAge( 3600L );
		UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
		source.registerCorsConfiguration( "/**", configuration );
		return source;
	}

}

参考

• Spring Security官方文档-授权架构
• How to login user from java code in Spring Security?