Spring Security源码分析一:Spring Security认证过程

2018/01/02 Spring Security

Spring Security是一个能够为基于Spring的企业应用系统提供声明式的安全访问控制解决方案的安全框架。它提供了一组可以在Spring应用上下文中配置的Bean,充分利用了Spring IoC,DI(控制反转Inversion of Control ,DI:Dependency Injection 依赖注入)和AOP(面向切面编程)功能,为应用系统提供声明式的安全访问控制功能,减少了为企业系统安全控制编写大量重复代码的工作。

类图

为了方便理解Spring Security认证流程,特意画了如下的类图,包含相关的核心认证类 http://dandandeshangni.oss-cn-beijing.aliyuncs.com/github/Spring%20Security/core-classdiagram.png

概述

核心验证器

AuthenticationManager

该对象提供了认证方法的入口,接收一个Authentiaton对象作为参数;

public interface AuthenticationManager {
	Authentication authenticate(Authentication authentication)
			throws AuthenticationException;
}

ProviderManager

它是 AuthenticationManager 的一个实现类,提供了基本的认证逻辑和方法;它包含了一个 List<AuthenticationProvider> 对象,通过 AuthenticationProvider 接口来扩展出不同的认证提供者(当Spring Security默认提供的实现类不能满足需求的时候可以扩展AuthenticationProvider 覆盖supports(Class<?> authentication) 方法);

验证逻辑

AuthenticationManager 接收 Authentication 对象作为参数,并通过 authenticate(Authentication) 方法对其进行验证;AuthenticationProvider实现类用来支撑对 Authentication 对象的验证动作;UsernamePasswordAuthenticationToken实现了 Authentication主要是将用户输入的用户名和密码进行封装,并供给 AuthenticationManager 进行验证;验证完成以后将返回一个认证成功的 Authentication 对象;

Authentication

Authentication对象中的主要方法

public interface Authentication extends Principal, Serializable {
	//#1.权限结合,可使用AuthorityUtils.commaSeparatedStringToAuthorityList("admin,ROLE_ADMIN")返回字符串权限集合
	Collection<? extends GrantedAuthority> getAuthorities();
	//#2.用户名密码认证时可以理解为密码
	Object getCredentials();
	//#3.认证时包含的一些信息。
	Object getDetails();
	//#4.用户名密码认证时可理解时用户名
	Object getPrincipal();
	#5.是否被认证,认证为true	
	boolean isAuthenticated();
	#6.设置是否能被认证
	void setAuthenticated(boolean isAuthenticated) throws IllegalArgumentException;

ProviderManager

ProviderManagerAuthenticationManager的实现类,提供了基本认证实现逻辑和流程;

public Authentication authenticate(Authentication authentication)
			throws AuthenticationException {
		//#1.获取当前的Authentication的认证类型
		Class<? extends Authentication> toTest = authentication.getClass();
		AuthenticationException lastException = null;
		Authentication result = null;
		boolean debug = logger.isDebugEnabled();
		//#2.遍历所有的providers使用supports方法判断该provider是否支持当前的认证类型,不支持的话继续遍历
		for (AuthenticationProvider provider : getProviders()) {
			if (!provider.supports(toTest)) {
				continue;
			}

			if (debug) {
				logger.debug("Authentication attempt using "
						+ provider.getClass().getName());
			}

			try {
				#3.支持的话调用providerauthenticat方法认证
				result = provider.authenticate(authentication);

				if (result != null) {
					#4.认证通过的话重新生成Authentication对应的Token
					copyDetails(authentication, result);
					break;
				}
			}
			catch (AccountStatusException e) {
				prepareException(e, authentication);
				// SEC-546: Avoid polling additional providers if auth failure is due to
				// invalid account status
				throw e;
			}
			catch (InternalAuthenticationServiceException e) {
				prepareException(e, authentication);
				throw e;
			}
			catch (AuthenticationException e) {
				lastException = e;
			}
		}

		if (result == null && parent != null) {
			// Allow the parent to try.
			try {
				#5.如果#1 没有验证通过,则使用父类型AuthenticationManager进行验证
				result = parent.authenticate(authentication);
			}
			catch (ProviderNotFoundException e) {
				// ignore as we will throw below if no other exception occurred prior to
				// calling parent and the parent
				// may throw ProviderNotFound even though a provider in the child already
				// handled the request
			}
			catch (AuthenticationException e) {
				lastException = e;
			}
		}
		#6. 是否擦出敏感信息
		if (result != null) {
			if (eraseCredentialsAfterAuthentication
					&& (result instanceof CredentialsContainer)) {
				// Authentication is complete. Remove credentials and other secret data
				// from authentication
				((CredentialsContainer) result).eraseCredentials();
			}

			eventPublisher.publishAuthenticationSuccess(result);
			return result;
		}

		// Parent was null, or didn't authenticate (or throw an exception).

		if (lastException == null) {
			lastException = new ProviderNotFoundException(messages.getMessage(
					"ProviderManager.providerNotFound",
					new Object[] { toTest.getName() },
					"No AuthenticationProvider found for {0}"));
		}

		prepareException(lastException, authentication);

		throw lastException;
	}
  1. 遍历所有的 Providers,然后依次执行该 Provider 的验证方法
    • 如果某一个 Provider 验证成功,则跳出循环不再执行后续的验证;
    • 如果验证成功,会将返回的 result 既 Authentication 对象进一步封装为 Authentication Token; 比如 UsernamePasswordAuthenticationToken、RememberMeAuthenticationToken 等;这些 Authentication Token 也都继承自 Authentication 对象;
  2. 如果 #1 没有任何一个 Provider 验证成功,则试图使用其 parent Authentication Manager 进行验证;
  3. 是否需要擦除密码等敏感信息;

AuthenticationProvider

ProviderManager 通过 AuthenticationProvider 扩展出更多的验证提供的方式;而 AuthenticationProvider 本身也就是一个接口,从类图中我们可以看出它的实现类AbstractUserDetailsAuthenticationProvider AbstractUserDetailsAuthenticationProvider的子类DaoAuthenticationProvider DaoAuthenticationProvider Spring Security中一个核心的Provider,对所有的数据库提供了基本方法和入口。

DaoAuthenticationProvider

DaoAuthenticationProvider主要做了以下事情

  1. 对用户身份尽心加密操作;
     #1.可直接返回BCryptPasswordEncoder,也可以自己实现该接口使用自己的加密算法核心方法String encode(CharSequence rawPassword);boolean matches(CharSequence rawPassword, String encodedPassword);
    private PasswordEncoder passwordEncoder;
    
  2. 实现了 AbstractUserDetailsAuthenticationProvider 两个抽象方法,
    1. 获取用户信息的扩展点
      protected final UserDetails retrieveUser(String username,
           UsernamePasswordAuthenticationToken authentication)
           throws AuthenticationException {
       UserDetails loadedUser;
      
       try {
           loadedUser = this.getUserDetailsService().loadUserByUsername(username);
       }
      

      主要是通过注入UserDetailsService接口对象,并调用其接口方法 loadUserByUsername(String username) 获取得到相关的用户信息。UserDetailsService接口非常重要。

    2. 实现 additionalAuthenticationChecks 的验证方法(主要验证密码);

AbstractUserDetailsAuthenticationProvider

AbstractUserDetailsAuthenticationProviderDaoAuthenticationProvider提供了基本的认证方法;

public Authentication authenticate(Authentication authentication)
			throws AuthenticationException {
		Assert.isInstanceOf(UsernamePasswordAuthenticationToken.class, authentication,
				messages.getMessage(
						"AbstractUserDetailsAuthenticationProvider.onlySupports",
						"Only UsernamePasswordAuthenticationToken is supported"));

		// Determine username
		String username = (authentication.getPrincipal() == null) ? "NONE_PROVIDED"
				: authentication.getName();

		boolean cacheWasUsed = true;
		UserDetails user = this.userCache.getUserFromCache(username);

		if (user == null) {
			cacheWasUsed = false;

			try {
				#1.获取用户信息由子类实现即DaoAuthenticationProvider
				user = retrieveUser(username,
						(UsernamePasswordAuthenticationToken) authentication);
			}
			catch (UsernameNotFoundException notFound) {
				logger.debug("User '" + username + "' not found");

				if (hideUserNotFoundExceptions) {
					throw new BadCredentialsException(messages.getMessage(
							"AbstractUserDetailsAuthenticationProvider.badCredentials",
							"Bad credentials"));
				}
				else {
					throw notFound;
				}
			}

			Assert.notNull(user,
					"retrieveUser returned null - a violation of the interface contract");
		}

		try {
			#2.前检查由DefaultPreAuthenticationChecks类实现(主要判断当前用户是否锁定,过期,冻结User接口)
			preAuthenticationChecks.check(user);
			#3.子类实现
			additionalAuthenticationChecks(user,
					(UsernamePasswordAuthenticationToken) authentication);
		}
		catch (AuthenticationException exception) {
			if (cacheWasUsed) {
				// There was a problem, so try again after checking
				// we're using latest data (i.e. not from the cache)
				cacheWasUsed = false;
				user = retrieveUser(username,
						(UsernamePasswordAuthenticationToken) authentication);
				preAuthenticationChecks.check(user);
				additionalAuthenticationChecks(user,
						(UsernamePasswordAuthenticationToken) authentication);
			}
			else {
				throw exception;
			}
		}
		#4.检测用户密码是否过期对应#2 User接口
		postAuthenticationChecks.check(user);

		if (!cacheWasUsed) {
			this.userCache.putUserInCache(user);
		}

		Object principalToReturn = user;

		if (forcePrincipalAsString) {
			principalToReturn = user.getUsername();
		}

		return createSuccessAuthentication(principalToReturn, authentication, user);
	}

AbstractUserDetailsAuthenticationProvider主要实现了AuthenticationProvider的接口方法 authenticate 并提供了相关的验证逻辑;

  1. 获取用户返回UserDetails AbstractUserDetailsAuthenticationProvider定义了一个抽象的方法
    protected abstract UserDetails retrieveUser(String username,
      UsernamePasswordAuthenticationToken authentication)
      throws AuthenticationException;
    
  2. 三步验证工作
    1. preAuthenticationChecks
    2. additionalAuthenticationChecks(抽象方法,子类实现)
    3. postAuthenticationChecks
  3. 将已通过验证的用户信息封装成 UsernamePasswordAuthenticationToken 对象并返回;该对象封装了用户的身份信息,以及相应的权限信息,相关源码如下,
    protected Authentication createSuccessAuthentication(Object principal,
         UsernamePasswordAuthenticationToken result = new UsernamePasswordAuthenticationToken(
                 principal, authentication.getCredentials(),
                 authoritiesMapper.mapAuthorities(user.getAuthorities()));
         result.setDetails(authentication.getDetails());
    
         return result;
     }
    

    UserDetailsService

    UserDetailsService是一个接口,提供了一个方法

    public interface UserDetailsService {
     UserDetails loadUserByUsername(String username) throws UsernameNotFoundException;
    }
    

    通过用户名 username 调用方法 loadUserByUsername 返回了一个UserDetails接口对象(对应AbstractUserDetailsAuthenticationProvider的三步验证方法);

    public interface UserDetails extends Serializable {
     #1.权限集合
     Collection<? extends GrantedAuthority> getAuthorities();
     #2.密码	
     String getPassword();
     #3.用户民
     String getUsername();
     #4.用户是否过期
     boolean isAccountNonExpired();
     #5.是否锁定	
     boolean isAccountNonLocked();
     #6.用户密码是否过期	
     boolean isCredentialsNonExpired();
     #7.账号是否可用(可理解为是否删除)
     boolean isEnabled();
    }
    

Spring 为UserDetailsService默认提供了一个实现类 org.springframework.security.core.userdetails.jdbc.JdbcDaoImpl

JdbcUserDetailsManager

该实现类主要是提供基于JDBC对 User 进行增、删、查、改的方法

public class JdbcUserDetailsManager extends JdbcDaoImpl implements UserDetailsManager,
		GroupManager {
	// ~ Static fields/initializers
	// =====================================================================================

	// UserDetailsManager SQL
	#1.定义了一些列对数据库操作的语句
	public static final String DEF_CREATE_USER_SQL = "insert into users (username, password, enabled) values (?,?,?)";
	public static final String DEF_DELETE_USER_SQL = "delete from users where username = ?";
	public static final String DEF_UPDATE_USER_SQL = "update users set password = ?, enabled = ? where username = ?";
	public static final String DEF_INSERT_AUTHORITY_SQL = "insert into authorities (username, authority) values (?,?)";
	public static final String DEF_DELETE_USER_AUTHORITIES_SQL = "delete from authorities where username = ?";
	public static final String DEF_USER_EXISTS_SQL = "select username from users where username = ?";
	public static final String DEF_CHANGE_PASSWORD_SQL = "update users set password = ? where username = ?";



InMemoryUserDetailsManager

该实现类主要是提供基于内存对 User 进行增、删、查、改的方法 `public class InMemoryUserDetailsManager implements UserDetailsManager { protected final Log logger = LogFactory.getLog(getClass()); #1.用MAP 存储 private final Map<String, MutableUserDetails> users = new HashMap<String, MutableUserDetails>();

private AuthenticationManager authenticationManager;

public InMemoryUserDetailsManager() {
}

public InMemoryUserDetailsManager(Collection<UserDetails> users) {
	for (UserDetails user : users) {
		createUser(user);
	}
}`

总结

UserDetailsService接口作为桥梁,是DaoAuthenticationProvier与特定用户信息来源进行解耦的地方,UserDetailsServiceUserDetailsUserDetailsManager所构成;UserDetailsUserDetailsManager各司其责,一个是对基本用户信息进行封装,一个是对基本用户信息进行管理;

特别注意UserDetailsServiceUserDetails以及UserDetailsManager都是可被用户自定义的扩展点,我们可以继承这些接口提供自己的读取用户来源和管理用户的方法,比如我们可以自己实现一个 与特定 ORM 框架,比如 Mybatis 或者 Hibernate,相关的UserDetailsServiceUserDetailsManager

时序图

http://dandandeshangni.oss-cn-beijing.aliyuncs.com/github/Spring%20Security/core-service-Sequence.png

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