spring security AuthenticationM

2022-02-09 本文已影响0人 do_young

AuthenticationManager相关类图

AuthenticationManager验证过程
AuthenticationManager验证过程涉及到的类和接口较多，我们就从这里开始逐一分析，首先我手画了一张图作为索引，这张图说明了各个类和接口之间的关系。
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AuthenticationManager 为认证管理接口类，其定义了认证方法authenticate()。
ProviderManager 为验证管理类，实现了接口AuthenticationManager ，并在认证方法authenticate() 中将身份认证委托给具有认证资格的AuthenticationProvider 进行身份认证。
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从上图中我们可以看到AuthenticationManager的实现类有很多，至于为什么我只提及到ProviderManager，有时间的小伙伴可以进行源码跟踪就能发现。

ProviderManager的成员变量

关于AuthenticationEventPublisher不懂的小伙伴可以查看Security中的认证事件发布器。
providers存储了一个 AuthenticationProvider 类型的list。和Security中的配置文件相对应。
MessageSourceAccessor一个国际化消息来源访问器，Security中用于信息提示。

AuthenticationProvider

接口认证类，定义了认证方法authenticate() 。
AbstractUserDetailsAuthenticationProvider 为认证抽象类，实现了接口 AuthenticationProvider 定义的认证方法 authenticate()。还定义了抽象方法 retrieveUser() 用于查询数据库用户信息，以及抽象方法 additionalAuthenticationChecks() 用作额外的身份验证检查。

DaoAuthenticationProvider

继承自抽象类AbstractUserDetailsAuthenticationProvider，实现了该类的方法 retrieveUser() 和 additionalAuthenticationChecks()。
DaoAuthenticationProvider 中还具有四个成员变量，分别是
USER_NOT_FOUND_PASSWORD
顾名思义，该变量是与PasswordEncoder一同使用的，当Security未找到用户时，用于PasswordEncoder.matches()执行的明文密码，以防止恶意用户确定用户名是否有效的旁路攻击的可能性。
PasswordEncoder
密码编码器，Security中的主要作用是用于将明文密码转换成密文，它采用SHA-256算法，迭代1024次，使用一个密钥(site-wide secret)以及8位随机盐对原密码进行加密。
userNotFoundEncodedPassword
同上方USER_NOT_FOUND_PASSWORD一致，只不过Security将其修饰为volatile的，确保了该变量不会因为编译器的优化而被省略。
关于volatile关键字不懂的请查看volatile理解
UserDetailsService
这个变量相信很多人都知道，不做过多的解释，Security中用于查询用户详细信息的接口
UserDetailsPasswordService
顾名思义，该接口用于修改用户的密码，只有在使用持久存储库时才有效，基于内存的方式会抛异常。(用处不大，只做了解即可)

流程分析

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static final class AuthenticationManagerDelegator implements AuthenticationManager {
        private AuthenticationManagerBuilder delegateBuilder;
        private AuthenticationManager delegate;
        private final Object delegateMonitor = new Object();

        AuthenticationManagerDelegator(AuthenticationManagerBuilder delegateBuilder) {
            Assert.notNull(delegateBuilder, "delegateBuilder cannot be null");
            this.delegateBuilder = delegateBuilder;
        }

        @Override
        public Authentication authenticate(Authentication authentication)
                throws AuthenticationException {
            if (this.delegate != null) {
                return this.delegate.authenticate(authentication);
            }

            synchronized (this.delegateMonitor) {
                if (this.delegate == null) {
                    this.delegate = this.delegateBuilder.getObject();
                    this.delegateBuilder = null;
                }
            }

            return this.delegate.authenticate(authentication);
        }

        @Override
        public String toString() {
            return "AuthenticationManagerDelegator [delegate=" + this.delegate + "]";
        }
    }

1、Security认证的入口为AuthenticationManager的authenticate()方法，从上面代码中我们可以看出，AuthenticationManagerDelegator使用了单例模式来防止AuthenticationManager在初始化时发生无限递归，因此我们只分析上方的两个实现类OAuth2AuthenticationManager和ProviderManager。

OAuth2AuthenticationManager

OAuth2AuthenticationManager的authenticate()的方法代码如下：

public Authentication authenticate(Authentication authentication) throws AuthenticationException {

        if (authentication == null) {
            throw new InvalidTokenException("Invalid token (token not found)");
        }
（1）     String token = (String) authentication.getPrincipal();
（2）     OAuth2Authentication auth = tokenServices.loadAuthentication(token);
        if (auth == null) {
            throw new InvalidTokenException("Invalid token: " + token);
        }

        Collection<String> resourceIds = auth.getOAuth2Request().getResourceIds();
        if (resourceId != null && resourceIds != null && !resourceIds.isEmpty() && !resourceIds.contains(resourceId)) {
            throw new OAuth2AccessDeniedException("Invalid token does not contain resource id (" + resourceId + ")");
        }

（3）     checkClientDetails(auth);

        if (authentication.getDetails() instanceof OAuth2AuthenticationDetails) {
            OAuth2AuthenticationDetails details = (OAuth2AuthenticationDetails) authentication.getDetails();
            // Guard against a cached copy of the same details
            if (!details.equals(auth.getDetails())) {
                // Preserve the authentication details from the one loaded by token services
                details.setDecodedDetails(auth.getDetails());
            }
        }
        auth.setDetails(authentication.getDetails());
        auth.setAuthenticated(true);
        return auth;
    }

private void checkClientDetails(OAuth2Authentication auth) {
        if (clientDetailsService != null) {
            ClientDetails client;
            try {
                            client = clientDetailsService.loadClientByClientId(auth.getOAuth2Request().getClientId());
            }
            catch (ClientRegistrationException e) {
                throw new OAuth2AccessDeniedException("Invalid token contains invalid client id");
            }
            Set<String> allowed = client.getScope();
            for (String scope : auth.getOAuth2Request().getScope()) {
                if (!allowed.contains(scope)) {
                    throw new OAuth2AccessDeniedException(
                            "Invalid token contains disallowed scope (" + scope + ") for this client");
                }
            }
        }
    }

OAuth2AuthenticationManager用于集成了OAuth2.0时使用的，如果没有用到，可以忽略。
其中：

(1)处的代码，期望传入的身份验证请求具有一个主体值，该主体值是一个访问令牌值（一般在（authorization header）请求头中）
(2)处从ResourceServerTokenServices通过查询数据库中 oauth_client_details该表，加载身份验证。
通过(3)处检查资源id是否包含在授权请求中。检查通过之后封装OAuth2认证实体返回给UsernamePasswordAuthenticationFilter以确定认证成功或失败。

ProviderManager

ProviderManager的authenticate()的方法代码如下：

public Authentication authenticate(Authentication authentication)
            throws AuthenticationException {
        Class<? extends Authentication> toTest = authentication.getClass();
        AuthenticationException lastException = null;
        AuthenticationException parentException = null;
        Authentication result = null;
        Authentication parentResult = null;
        boolean debug = logger.isDebugEnabled();

（1）     for (AuthenticationProvider provider : getProviders()) {
            if (!provider.supports(toTest)) {
                continue;
            }

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

            try {
（2）             result = provider.authenticate(authentication);

                if (result != null) {
                    copyDetails(authentication, result);
                    break;
                }
            }
            catch (AccountStatusException | InternalAuthenticationServiceException e) {
                prepareException(e, authentication);
                // SEC-546: Avoid polling additional providers if auth failure is due to
                // invalid account status
                throw e;
            } catch (AuthenticationException e) {
                lastException = e;
            }
        }

        if (result == null && parent != null) {
            // Allow the parent to try.
            try {
                result = parentResult = 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 = parentException = e;
            }
        }

        if (result != null) {
            if (eraseCredentialsAfterAuthentication
                    && (result instanceof CredentialsContainer)) {
                // Authentication is complete. Remove credentials and other secret data
                // from authentication
                ((CredentialsContainer) result).eraseCredentials();
            }

            // If the parent AuthenticationManager was attempted and successful than it will publish an AuthenticationSuccessEvent
            // This check prevents a duplicate AuthenticationSuccessEvent if the parent AuthenticationManager already published it
            if (parentResult == null) {
                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}"));
        }

        // If the parent AuthenticationManager was attempted and failed than it will publish an AbstractAuthenticationFailureEvent
        // This check prevents a duplicate AbstractAuthenticationFailureEvent if the parent AuthenticationManager already published it
        if (parentException == null) {
            prepareException(lastException, authentication);
        }

        throw lastException;
    }

其中：

(1)处的代码从ProviderManager的属性providers[List<authenticationprovider style="margin: 0px; padding: 0px;">]</authenticationprovider>中通过for循环拿到支持该类认证的AuthenticationProvider用于认证处理。
(2)处的代码，对用户进行身份认证，认证过程如下所示。

在上面(2)处的代码，使用了AbstractUserDetailsAuthenticationProvider的authenticate()方法，接下来具体分析该方法，代码如下：

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）             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 {
            preAuthenticationChecks.check(user);
（2）         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;
            }
        }

        postAuthenticationChecks.check(user);

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

        Object principalToReturn = user;

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

（3）     return createSuccessAuthentication(principalToReturn, authentication, user);
    }

(3)处创建一个成功的身份认证令牌并将用户认证信息其放置到UsernamePasswordAuthenticationToken中。

查看源码我们得知，AbstractUserDetailsAuthenticationProvider的(1)处和(2)处调用的方法没有具体的实现，因此我们接下来分析它的子类DaoAuthenticationProvider
retrieveUser()

protected final UserDetails retrieveUser(String username,
            UsernamePasswordAuthenticationToken authentication)
            throws AuthenticationException {
        prepareTimingAttackProtection();
        try {
(1)         UserDetails loadedUser = this.getUserDetailsService().loadUserByUsername(username);
            if (loadedUser == null) {
                throw new InternalAuthenticationServiceException(
                        "UserDetailsService returned null, which is an interface contract violation");
            }
            return loadedUser;
        }
        catch (UsernameNotFoundException ex) {
            mitigateAgainstTimingAttack(authentication);
            throw ex;
        }
        catch (InternalAuthenticationServiceException ex) {
            throw ex;
        }
        catch (Exception ex) {
            throw new InternalAuthenticationServiceException(ex.getMessage(), ex);
        }
    }

(1)处调用DaoAuthenticationProvider成员变量UserDetailsService的方法loadUserByUsername()从数据库中加载用户详细信息（用过Security的对此处应该是很熟悉了）

additionalAuthenticationChecks()

protected void additionalAuthenticationChecks(UserDetails userDetails,
            UsernamePasswordAuthenticationToken authentication)
            throws AuthenticationException {
        if (authentication.getCredentials() == null) {
            logger.debug("Authentication failed: no credentials provided");

            throw new BadCredentialsException(messages.getMessage(
                    "AbstractUserDetailsAuthenticationProvider.badCredentials",
                    "Bad credentials"));
        }

（1）     String presentedPassword = authentication.getCredentials().toString();

（2）     if (!passwordEncoder.matches(presentedPassword, userDetails.getPassword())) {
            logger.debug("Authentication failed: password does not match stored value");

            throw new BadCredentialsException(messages.getMessage(
                    "AbstractUserDetailsAuthenticationProvider.badCredentials",
                    "Bad credentials"));
        }
    }

(1)处从UsernamePasswordAuthenticationToken中调出了密码，再由(2)处通过调用成员变量passwordEncoder对其密码进行验证。