Spring Security 架构与源码分析

Spring Security 主要实现了Authentication（认证，解决who are you? ） 和 Access Control（访问控制，也就是what are you allowed to do？，也称为Authorization）。Spring Security在架构上将认证与授权分离，并提供了扩展点。

核心对象

主要代码在spring-security-core包下面。要了解Spring Security，需要先关注里面的核心对象。

SecurityContextHolder, SecurityContext 和 Authentication

SecurityContextHolder 是 SecurityContext的存放容器，默认使用ThreadLocal 存储，意味SecurityContext在相同线程中的方法都可用。
SecurityContext主要是存储应用的principal信息，在Spring Security中用Authentication 来表示。

获取principal：

Object principal = SecurityContextHolder.getContext().getAuthentication().getPrincipal();

if (principal instanceof UserDetails) {
String username = ((UserDetails)principal).getUsername();
} else {
String username = principal.toString();
}

在Spring Security中，可以看一下Authentication定义：

public interface Authentication extends Principal, Serializable {

    Collection<? extends GrantedAuthority> getAuthorities();

    /**
     * 通常是密码
     */
    Object getCredentials();

    /**
     * Stores additional details about the authentication request. These might be an IP
     * address, certificate serial number etc.
     */
    Object getDetails();

    /**
     * 用来标识是否已认证，如果使用用户名和密码登录,通常是用户名 
     */
    Object getPrincipal();

    /**
     * 是否已认证
     */
    boolean isAuthenticated();

    void setAuthenticated(boolean isAuthenticated) throws IllegalArgumentException;
}

在实际应用中，通常使用UsernamePasswordAuthenticationToken：

public abstract class AbstractAuthenticationToken implements Authentication,
        CredentialsContainer {
        }
public class UsernamePasswordAuthenticationToken extends AbstractAuthenticationToken {
}

一个常见的认证过程通常是这样的，创建一个UsernamePasswordAuthenticationToken，然后交给authenticationManager认证（后面详细说明），认证通过则通过SecurityContextHolder存放Authentication信息。

 UsernamePasswordAuthenticationToken authenticationToken =
            new UsernamePasswordAuthenticationToken(loginVM.getUsername(), loginVM.getPassword());

Authentication authentication = this.authenticationManager.authenticate(authenticationToken);
SecurityContextHolder.getContext().setAuthentication(authentication);

UserDetails与UserDetailsService

UserDetails 是Spring Security里的一个关键接口，他用来表示一个principal。

public interface UserDetails extends Serializable {
    /**
     * 用户的授权信息，可以理解为角色
     */
    Collection<? extends GrantedAuthority> getAuthorities();

    /**
     * 用户密码
     *
     * @return the password
     */
    String getPassword();

    /**
     * 用户名 
     *   */
    String getUsername();

    boolean isAccountNonExpired();

    boolean isAccountNonLocked();

    boolean isCredentialsNonExpired();

    boolean isEnabled();
}

UserDetails提供了认证所需的必要信息，在实际使用里，可以自己实现UserDetails，并增加额外的信息，比如email、mobile等信息。

在Authentication中的principal通常是用户名，我们可以通过UserDetailsService来通过principal获取UserDetails：

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

GrantedAuthority

在UserDetails里说了，GrantedAuthority可以理解为角色，例如 ROLE_ADMINISTRATOR or ROLE_HR_SUPERVISOR。

小结

• SecurityContextHolder, 用来访问 SecurityContext.
• SecurityContext, 用来存储Authentication .
• Authentication, 代表凭证.
• GrantedAuthority, 代表权限.
• UserDetails, 用户信息.
• UserDetailsService,获取用户信息.

Authentication认证

AuthenticationManager

实现认证主要是通过AuthenticationManager接口，它只包含了一个方法：

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

authenticate()方法主要做三件事：

1. 如果验证通过，返回Authentication（通常带上authenticated=true）。
2. 认证失败抛出AuthenticationException
3. 如果无法确定，则返回null

AuthenticationException是运行时异常,它通常由应用程序按通用方式处理，用户代码通常不用特意被捕获和处理这个异常。

AuthenticationManager的默认实现是ProviderManager，它委托一组AuthenticationProvider实例来实现认证。
AuthenticationProvider和AuthenticationManager类似，都包含authenticate，但它有一个额外的方法supports，以允许查询调用方是否支持给定Authentication类型：

public interface AuthenticationProvider {

    Authentication authenticate(Authentication authentication)
            throws AuthenticationException;
    boolean supports(Class<?> authentication);
}

ProviderManager包含一组AuthenticationProvider，执行authenticate时，遍历Providers，然后调用supports，如果支持，则执行遍历当前provider的authenticate方法，如果一个provider认证成功，则break。

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

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

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

            try {
                result = provider.authenticate(authentication);

                if (result != null) {
                    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 {
                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;
            }
        }

        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;
    }

从上面的代码可以看出， ProviderManager有一个可选parent，如果parent不为空，则调用parent.authenticate(authentication)

AuthenticationProvider

AuthenticationProvider有多种实现，大家最关注的通常是DaoAuthenticationProvider，继承于AbstractUserDetailsAuthenticationProvider，核心是通过UserDetails来实现认证,DaoAuthenticationProvider默认会自动加载，不用手动配。

先来看AbstractUserDetailsAuthenticationProvider，看最核心的authenticate：

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

        //  获取用户名
        String username = (authentication.getPrincipal() == null) ? "NONE_PROVIDED"
                : authentication.getName();

        boolean cacheWasUsed = true;
        // 从缓存获取
        UserDetails user = this.userCache.getUserFromCache(username);

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

            try {
               // retrieveUser 抽象方法，获取用户
                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 {
            // 预先检查，DefaultPreAuthenticationChecks，检查用户是否被lock或者账号是否可用
            preAuthenticationChecks.check(user);
            
            // 抽象方法，自定义检验
            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;
            }
        }
      
        // 后置检查 DefaultPostAuthenticationChecks，检查isCredentialsNonExpired
        postAuthenticationChecks.check(user);

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

        Object principalToReturn = user;

        if (forcePrincipalAsString) {
            principalToReturn = user.getUsername();
        }
   
        return createSuccessAuthentication(principalToReturn, authentication, user);
    }

上面的检验主要基于UserDetails实现，其中获取用户和检验逻辑由具体的类去实现，默认实现是DaoAuthenticationProvider，这个类的核心是让开发者提供UserDetailsService来获取UserDetails以及 PasswordEncoder来检验密码是否有效：

private UserDetailsService userDetailsService;
private PasswordEncoder passwordEncoder;

看具体的实现，retrieveUser,直接调用userDetailsService获取用户：

protected final UserDetails retrieveUser(String username,
            UsernamePasswordAuthenticationToken authentication)
            throws AuthenticationException {
        UserDetails loadedUser;

        try {
            loadedUser = this.getUserDetailsService().loadUserByUsername(username);
        }
        catch (UsernameNotFoundException notFound) {
            if (authentication.getCredentials() != null) {
                String presentedPassword = authentication.getCredentials().toString();
                passwordEncoder.isPasswordValid(userNotFoundEncodedPassword,
                        presentedPassword, null);
            }
            throw notFound;
        }
        catch (Exception repositoryProblem) {
            throw new InternalAuthenticationServiceException(
                    repositoryProblem.getMessage(), repositoryProblem);
        }

        if (loadedUser == null) {
            throw new InternalAuthenticationServiceException(
                    "UserDetailsService returned null, which is an interface contract violation");
        }
        return loadedUser;
    }

再来看验证：

protected void additionalAuthenticationChecks(UserDetails userDetails,
            UsernamePasswordAuthenticationToken authentication)
            throws AuthenticationException {
        Object salt = null;

        if (this.saltSource != null) {
            salt = this.saltSource.getSalt(userDetails);
        }

        if (authentication.getCredentials() == null) {
            logger.debug("Authentication failed: no credentials provided");

            throw new BadCredentialsException(messages.getMessage(
                    "AbstractUserDetailsAuthenticationProvider.badCredentials",
                    "Bad credentials"));
        }
        // 获取用户密码
        String presentedPassword = authentication.getCredentials().toString();
        // 比较passwordEncoder后的密码是否和userdetails的密码一致
        if (!passwordEncoder.isPasswordValid(userDetails.getPassword(),
                presentedPassword, salt)) {
            logger.debug("Authentication failed: password does not match stored value");

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

小结：要自定义认证，使用DaoAuthenticationProvider，只需要为其提供PasswordEncoder和UserDetailsService就可以了。

定制 Authentication Managers

Spring Security提供了一个Builder类AuthenticationManagerBuilder，借助它可以快速实现自定义认证。

看官方源码说明：

SecurityBuilder used to create an AuthenticationManager . Allows for easily building in memory authentication, LDAP authentication, JDBC based authentication, adding UserDetailsService , and adding AuthenticationProvider's.

AuthenticationManagerBuilder可以用来Build一个AuthenticationManager，可以创建基于内存的认证、LDAP认证、 JDBC认证，以及添加UserDetailsService和AuthenticationProvider。

简单使用：

@Configuration
@EnableWebSecurity
@EnableGlobalMethodSecurity(prePostEnabled = true, securedEnabled = true)
public class ApplicationSecurity extends WebSecurityConfigurerAdapter {


  public SecurityConfiguration(AuthenticationManagerBuilder authenticationManagerBuilder, UserDetailsService userDetailsService,TokenProvider tokenProvider,CorsFilter corsFilter, SecurityProblemSupport problemSupport) {
        this.authenticationManagerBuilder = authenticationManagerBuilder;
        this.userDetailsService = userDetailsService;
        this.tokenProvider = tokenProvider;
        this.corsFilter = corsFilter;
        this.problemSupport = problemSupport;
    }

    @PostConstruct
    public void init() {
        try {
            authenticationManagerBuilder
                .userDetailsService(userDetailsService)
                .passwordEncoder(passwordEncoder());
        } catch (Exception e) {
            throw new BeanInitializationException("Security configuration failed", e);
        }
    }

   @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()
            .antMatchers("/api/register").permitAll()
            .antMatchers("/api/activate").permitAll()
            .antMatchers("/api/authenticate").permitAll()
            .antMatchers("/api/account/reset-password/init").permitAll()
            .antMatchers("/api/account/reset-password/finish").permitAll()
            .antMatchers("/api/profile-info").permitAll()
            .antMatchers("/api/**").authenticated()
            .antMatchers("/management/health").permitAll()
            .antMatchers("/management/**").hasAuthority(AuthoritiesConstants.ADMIN)
            .antMatchers("/v2/api-docs/**").permitAll()
            .antMatchers("/swagger-resources/configuration/ui").permitAll()
            .antMatchers("/swagger-ui/index.html").hasAuthority(AuthoritiesConstants.ADMIN)
        .and()
            .apply(securityConfigurerAdapter());

    }
}

授权与访问控制

一旦认证成功，我们可以继续进行授权，授权是通过AccessDecisionManager来实现的。框架有三种实现，默认是AffirmativeBased，通过AccessDecisionVoter决策，有点像ProviderManager委托给AuthenticationProviders来认证。

public void decide(Authentication authentication, Object object,
            Collection<ConfigAttribute> configAttributes) throws AccessDeniedException {
        int deny = 0;
        // 遍历DecisionVoter 
        for (AccessDecisionVoter voter : getDecisionVoters()) {
            // 投票
            int result = voter.vote(authentication, object, configAttributes);

            if (logger.isDebugEnabled()) {
                logger.debug("Voter: " + voter + ", returned: " + result);
            }

            switch (result) {
            case AccessDecisionVoter.ACCESS_GRANTED:
                return;

            case AccessDecisionVoter.ACCESS_DENIED:
                deny++;

                break;

            default:
                break;
            }
        }
       
        // 一票否决
        if (deny > 0) {
            throw new AccessDeniedException(messages.getMessage(
                    "AbstractAccessDecisionManager.accessDenied", "Access is denied"));
        }

        // To get this far, every AccessDecisionVoter abstained
        checkAllowIfAllAbstainDecisions();
    }

来看AccessDecisionVoter：

boolean supports(ConfigAttribute attribute);

boolean supports(Class<?> clazz);

int vote(Authentication authentication, S object,
        Collection<ConfigAttribute> attributes);

object是用户要访问的资源，ConfigAttribute则是访问object要满足的条件，通常payload是字符串，比如ROLE_ADMIN 。所以我们来看下RoleVoter的实现，其核心就是从authentication提取出GrantedAuthority，然后和ConfigAttribute比较是否满足条件。

public boolean supports(ConfigAttribute attribute) {
        if ((attribute.getAttribute() != null)
                && attribute.getAttribute().startsWith(getRolePrefix())) {
            return true;
        }
        else {
            return false;
        }
    }
    
public boolean supports(Class<?> clazz) {
        return true;
    }


public int vote(Authentication authentication, Object object,
            Collection<ConfigAttribute> attributes) {
        if(authentication == null) {
            return ACCESS_DENIED;
        }
        int result = ACCESS_ABSTAIN;
        
        // 获取GrantedAuthority信息
        Collection<? extends GrantedAuthority> authorities = extractAuthorities(authentication);

        for (ConfigAttribute attribute : attributes) {
            if (this.supports(attribute)) {
                // 默认拒绝访问
                result = ACCESS_DENIED;

                // Attempt to find a matching granted authority
                for (GrantedAuthority authority : authorities) {
                     // 判断是否有匹配的 authority
                    if (attribute.getAttribute().equals(authority.getAuthority())) {
                        // 可访问
                        return ACCESS_GRANTED;
                    }
                }
            }
        }

        return result;
    }

这里要疑问，ConfigAttribute哪来的？其实就是上面ApplicationSecurity的configure里的。

web security 如何实现

Web层中的Spring Security（用于UI和HTTP后端）基于Servlet Filters，下图显示了单个HTTP请求的处理程序的典型分层。

[图片上传失败...(image-47e8d6-1528938759966)]

Spring Security通过FilterChainProxy作为单一的Filter注册到web层，Proxy内部的Filter。

[图片上传失败...(image-3fba6-1528938759966)]

FilterChainProxy相当于一个filter的容器，通过VirtualFilterChain来依次调用各个内部filter

public void doFilter(ServletRequest request, ServletResponse response,
            FilterChain chain) throws IOException, ServletException {
        boolean clearContext = request.getAttribute(FILTER_APPLIED) == null;
        if (clearContext) {
            try {
                request.setAttribute(FILTER_APPLIED, Boolean.TRUE);
                doFilterInternal(request, response, chain);
            }
            finally {
                SecurityContextHolder.clearContext();
                request.removeAttribute(FILTER_APPLIED);
            }
        }
        else {
            doFilterInternal(request, response, chain);
        }
    }

    private void doFilterInternal(ServletRequest request, ServletResponse response,
            FilterChain chain) throws IOException, ServletException {

        FirewalledRequest fwRequest = firewall
                .getFirewalledRequest((HttpServletRequest) request);
        HttpServletResponse fwResponse = firewall
                .getFirewalledResponse((HttpServletResponse) response);

        List<Filter> filters = getFilters(fwRequest);

        if (filters == null || filters.size() == 0) {
            if (logger.isDebugEnabled()) {
                logger.debug(UrlUtils.buildRequestUrl(fwRequest)
                        + (filters == null ? " has no matching filters"
                                : " has an empty filter list"));
            }

            fwRequest.reset();

            chain.doFilter(fwRequest, fwResponse);

            return;
        }

        VirtualFilterChain vfc = new VirtualFilterChain(fwRequest, chain, filters);
        vfc.doFilter(fwRequest, fwResponse);
    }
    
    private static class VirtualFilterChain implements FilterChain {
        private final FilterChain originalChain;
        private final List<Filter> additionalFilters;
        private final FirewalledRequest firewalledRequest;
        private final int size;
        private int currentPosition = 0;

        private VirtualFilterChain(FirewalledRequest firewalledRequest,
                FilterChain chain, List<Filter> additionalFilters) {
            this.originalChain = chain;
            this.additionalFilters = additionalFilters;
            this.size = additionalFilters.size();
            this.firewalledRequest = firewalledRequest;
        }

        public void doFilter(ServletRequest request, ServletResponse response)
                throws IOException, ServletException {
            if (currentPosition == size) {
                if (logger.isDebugEnabled()) {
                    logger.debug(UrlUtils.buildRequestUrl(firewalledRequest)
                            + " reached end of additional filter chain; proceeding with original chain");
                }

                // Deactivate path stripping as we exit the security filter chain
                this.firewalledRequest.reset();

                originalChain.doFilter(request, response);
            }
            else {
                currentPosition++;

                Filter nextFilter = additionalFilters.get(currentPosition - 1);

                if (logger.isDebugEnabled()) {
                    logger.debug(UrlUtils.buildRequestUrl(firewalledRequest)
                            + " at position " + currentPosition + " of " + size
                            + " in additional filter chain; firing Filter: '"
                            + nextFilter.getClass().getSimpleName() + "'");
                }

                nextFilter.doFilter(request, response, this);
            }
        }
    }
    

spring security动态配置url权限

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：

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：

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：

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:

  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。

@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。

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。

@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。

基于spring security 实现前后端分离项目权限控制

前后端分离的项目，前端有菜单（menu），后端有API（backendApi），一个menu对应的页面有N个API接口来支持，本文介绍如何基于spring security实现前后端的同步权限控制。

实现思路

还是基于Role来实现，具体的思路是，一个Role拥有多个Menu，一个menu有多个backendApi，其中Role和menu，以及menu和backendApi都是ManyToMany关系。

验证授权也很简单，用户登陆系统时，获取Role关联的Menu，页面访问后端API时，再验证下用户是否有访问API的权限。

domain定义

我们用JPA来实现，先来定义Role

public class Role implements Serializable {


    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    /**
     * 名称
     */
    @NotNull
    @ApiModelProperty(value = "名称", required = true)
    @Column(name = "name", nullable = false)
    private String name;

    /**
     * 备注
     */
    @ApiModelProperty(value = "备注")
    @Column(name = "remark")
    private String remark;

    @JsonIgnore
    @ManyToMany
    @JoinTable(
        name = "role_menus",
        joinColumns = {@JoinColumn(name = "role_id", referencedColumnName = "id")},
        inverseJoinColumns = {@JoinColumn(name = "menu_id", referencedColumnName = "id")})
    @Cache(usage = CacheConcurrencyStrategy.NONSTRICT_READ_WRITE)
    @BatchSize(size = 100)
    private Set<Menu> menus = new HashSet<>();
    
    }

以及Menu：

public class Menu implements Serializable {


    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(name = "parent_id")
    private Integer parentId;

    /**
     * 文本
     */
    @ApiModelProperty(value = "文本")
    @Column(name = "text")
    private String text;
    
    @ApiModelProperty(value = "angular路由")
    @Column(name = "link")
    private String link;
    
    @ManyToMany
    @JsonIgnore
    @JoinTable(name = "backend_api_menus",
        joinColumns = @JoinColumn(name="menus_id", referencedColumnName="id"),
        inverseJoinColumns = @JoinColumn(name="backend_apis_id", referencedColumnName="id"))
    @Cache(usage = CacheConcurrencyStrategy.NONSTRICT_READ_WRITE)
    private Set<BackendApi> backendApis = new HashSet<>();

    @ManyToMany(mappedBy = "menus")
    @JsonIgnore
    private Set<Role> roles = new HashSet<>();
    }
    
    

最后是BackendApi，区分method（HTTP请求方法）、tag（哪一个Controller）和path（API请求路径）：

public class BackendApi implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(name = "tag")
    private String tag;

    @Column(name = "path")
    private String path;

    @Column(name = "method")
    private String method;

    @Column(name = "summary")
    private String summary;

    @Column(name = "operation_id")
    private String operationId;

    @ManyToMany(mappedBy = "backendApis")
    @Cache(usage = CacheConcurrencyStrategy.NONSTRICT_READ_WRITE)
    private Set<Menu> menus = new HashSet<>();
    
    }

管理页面实现

Menu菜单是业务需求确定的，因此提供CRUD编辑即可。
BackendAPI，可以通过swagger来获取。
前端选择ng-algin，参见Angular 中后台前端解决方案 - Ng Alain 介绍

通过swagger获取BackendAPI

获取swagger api有多种方法，最简单的就是访问http接口获取json，然后解析，这很简单，这里不赘述，还有一种就是直接调用相关API获取Swagger对象。

查看官方的web代码，可以看到获取数据大概是这样的：

        String groupName = Optional.fromNullable(swaggerGroup).or(Docket.DEFAULT_GROUP_NAME);
        Documentation documentation = documentationCache.documentationByGroup(groupName);
        if (documentation == null) {
            return new ResponseEntity<Json>(HttpStatus.NOT_FOUND);
        }
        Swagger swagger = mapper.mapDocumentation(documentation);
        UriComponents uriComponents = componentsFrom(servletRequest, swagger.getBasePath());
        swagger.basePath(Strings.isNullOrEmpty(uriComponents.getPath()) ? "/" : uriComponents.getPath());
        if (isNullOrEmpty(swagger.getHost())) {
            swagger.host(hostName(uriComponents));
        }
        return new ResponseEntity<Json>(jsonSerializer.toJson(swagger), HttpStatus.OK);

其中的documentationCache、environment、mapper等可以直接Autowired获得：

@Autowired
    public SwaggerResource(
        Environment environment,
        DocumentationCache documentationCache,
        ServiceModelToSwagger2Mapper mapper,
        BackendApiRepository backendApiRepository,
        JsonSerializer jsonSerializer) {

        this.hostNameOverride = environment.getProperty("springfox.documentation.swagger.v2.host", "DEFAULT");
        this.documentationCache = documentationCache;
        this.mapper = mapper;
        this.jsonSerializer = jsonSerializer;

        this.backendApiRepository = backendApiRepository;

    }

然后我们自动加载就简单了，写一个updateApi接口，读取swagger对象，然后解析成BackendAPI，存储到数据库：

@RequestMapping(
        value = "/api/updateApi",
        method = RequestMethod.GET,
        produces = { APPLICATION_JSON_VALUE, HAL_MEDIA_TYPE })
    @PropertySourcedMapping(
        value = "${springfox.documentation.swagger.v2.path}",
        propertyKey = "springfox.documentation.swagger.v2.path")
    @ResponseBody
    public ResponseEntity<Json> updateApi(
        @RequestParam(value = "group", required = false) String swaggerGroup) {

        // 加载已有的api
        Map<String,Boolean> apiMap = Maps.newHashMap();
        List<BackendApi> apis = backendApiRepository.findAll();
        apis.stream().forEach(api->apiMap.put(api.getPath()+api.getMethod(),true));

        // 获取swagger
        String groupName = Optional.fromNullable(swaggerGroup).or(Docket.DEFAULT_GROUP_NAME);
        Documentation documentation = documentationCache.documentationByGroup(groupName);
        if (documentation == null) {
            return new ResponseEntity<Json>(HttpStatus.NOT_FOUND);
        }
        Swagger swagger = mapper.mapDocumentation(documentation);

        // 加载到数据库
        for(Map.Entry<String, Path> item : swagger.getPaths().entrySet()){
            String path = item.getKey();
            Path pathInfo = item.getValue();
            createApiIfNeeded(apiMap, path,  pathInfo.getGet(), HttpMethod.GET.name());
            createApiIfNeeded(apiMap, path,  pathInfo.getPost(), HttpMethod.POST.name());
            createApiIfNeeded(apiMap, path,  pathInfo.getDelete(), HttpMethod.DELETE.name());
            createApiIfNeeded(apiMap, path,  pathInfo.getPut(), HttpMethod.PUT.name());
        }
        return new ResponseEntity<Json>(HttpStatus.OK);
    }

其中createApiIfNeeded，先判断下是否存在，不存在的则新增：

 private void createApiIfNeeded(Map<String, Boolean> apiMap, String path, Operation operation, String method) {
        if(operation==null) {
            return;
        }
        if(!apiMap.containsKey(path+ method)){
            apiMap.put(path+ method,true);

            BackendApi api = new BackendApi();
            api.setMethod( method);
            api.setOperationId(operation.getOperationId());
            api.setPath(path);
            api.setTag(operation.getTags().get(0));
            api.setSummary(operation.getSummary());

            // 保存
            this.backendApiRepository.save(api);
        }
    }

最后，做一个简单页面展示即可：

enter description here

菜单管理

新增和修改页面，可以选择上级菜单，后台API做成按tag分组，可多选即可：

enter description here

列表页面

enter description here

角色管理

普通的CRUD，最主要的增加一个菜单授权页面，菜单按层级显示即可：

enter description here

认证实现

管理页面可以做成千奇百样，最核心的还是如何实现认证。

在上一篇文章spring security实现动态配置url权限的两种方法里我们说了，可以自定义FilterInvocationSecurityMetadataSource来实现。

实现FilterInvocationSecurityMetadataSource接口即可，核心是根据FilterInvocation的Request的method和path，获取对应的Role，然后交给RoleVoter去判断是否有权限。

自定义FilterInvocationSecurityMetadataSource

我们新建一个DaoSecurityMetadataSource实现FilterInvocationSecurityMetadataSource接口，主要看getAttributes方法：

     @Override
    public Collection<ConfigAttribute> getAttributes(Object object) throws IllegalArgumentException {
        FilterInvocation fi = (FilterInvocation) object;

        List<Role> neededRoles = this.getRequestNeededRoles(fi.getRequest().getMethod(), fi.getRequestUrl());

        if (neededRoles != null) {
            return SecurityConfig.createList(neededRoles.stream().map(role -> role.getName()).collect(Collectors.toList()).toArray(new String[]{}));
        }

        //  返回默认配置
        return superMetadataSource.getAttributes(object);
    }

核心是getRequestNeededRoles怎么实现，获取到干净的RequestUrl（去掉参数）,然后看是否有对应的backendAPI，如果没有，则有可能该API有path参数，我们可以去掉最后的path，去库里模糊匹配，直到找到。

 public List<Role> getRequestNeededRoles(String method, String path) {
        String rawPath = path;
        //  remove parameters
        if(path.indexOf("?")>-1){
            path = path.substring(0,path.indexOf("?"));
        }
        // /menus/{id}
        BackendApi api = backendApiRepository.findByPathAndMethod(path, method);
        if (api == null){
            // try fetch by remove last path
            api = loadFromSimilarApi(method, path, rawPath);
        }

        if (api != null && api.getMenus().size() > 0) {
            return api.getMenus()
                .stream()
                .flatMap(menu -> menuRepository.findOneWithRolesById(menu.getId()).getRoles().stream())
                .collect(Collectors.toList());
        }
        return null;
    }

    private BackendApi loadFromSimilarApi(String method, String path, String rawPath) {
        if(path.lastIndexOf("/")>-1){
            path = path.substring(0,path.lastIndexOf("/"));
            List<BackendApi> apis = backendApiRepository.findByPathStartsWithAndMethod(path, method);

            // 如果为空，再去掉一层path
            while(apis==null){
                if(path.lastIndexOf("/")>-1) {
                    path = path.substring(0, path.lastIndexOf("/"));
                    apis = backendApiRepository.findByPathStartsWithAndMethod(path, method);
                }else{
                    break;
                }
            }

            if(apis!=null){
                for(BackendApi backendApi : apis){
                    if (antPathMatcher.match(backendApi.getPath(), rawPath)) {
                        return backendApi;
                    }
                }
            }
        }
        return null;
    }

其中，BackendApiRepository：

    @EntityGraph(attributePaths = "menus")
    BackendApi findByPathAndMethod(String path,String method);

    @EntityGraph(attributePaths = "menus")
    List<BackendApi> findByPathStartsWithAndMethod(String path,String method);
    

以及MenuRepository

    @EntityGraph(attributePaths = "roles")
    Menu findOneWithRolesById(long id);

使用DaoSecurityMetadataSource

需要注意的是，在DaoSecurityMetadataSource里，不能直接注入Repository，我们可以给DaoSecurityMetadataSource添加一个方法，方便传入：

   public void init(MenuRepository menuRepository, BackendApiRepository backendApiRepository) {
        this.menuRepository = menuRepository;
        this.backendApiRepository = backendApiRepository;
    }

然后建立一个容器，存储实例化的DaoSecurityMetadataSource，我们可以建立如下的ApplicationContext来作为对象容器，存取对象：

public class ApplicationContext {
    static Map<Class<?>,Object> beanMap = Maps.newConcurrentMap();

    public static <T> T getBean(Class<T> requireType){
        return (T) beanMap.get(requireType);
    }

    public static void registerBean(Object item){
        beanMap.put(item.getClass(),item);
    }
}

在SecurityConfiguration配置中使用DaoSecurityMetadataSource，并通过ApplicationContext.registerBean将DaoSecurityMetadataSource注册：

 @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            .addFilterBefore(corsFilter, UsernamePasswordAuthenticationFilter.class)
            .exceptionHandling()
            .authenticationEntryPoint(problemSupport)
            .accessDeniedHandler(problemSupport)
            ....
           // .withObjectPostProcessor()
            // 自定义accessDecisionManager
            .accessDecisionManager(accessDecisionManager())
            // 自定义FilterInvocationSecurityMetadataSource
            .withObjectPostProcessor(new ObjectPostProcessor<FilterSecurityInterceptor>() {
                @Override
                public <O extends FilterSecurityInterceptor> O postProcess(
                    O fsi) {
                    fsi.setSecurityMetadataSource(daoSecurityMetadataSource(fsi.getSecurityMetadataSource()));
                    return fsi;
                }
            })
        .and()
            .apply(securityConfigurerAdapter());

    }

    @Bean
    public DaoSecurityMetadataSource daoSecurityMetadataSource(FilterInvocationSecurityMetadataSource filterInvocationSecurityMetadataSource) {
        DaoSecurityMetadataSource securityMetadataSource = new DaoSecurityMetadataSource(filterInvocationSecurityMetadataSource);
        ApplicationContext.registerBean(securityMetadataSource);
        return securityMetadataSource;
    }

最后，在程序启动后，通过ApplicationContext.getBean获取到daoSecurityMetadataSource，然后调用init注入Repository

 public static void postInit(){
        ApplicationContext
            .getBean(DaoSecurityMetadataSource.class)
 .init(applicationContext.getBean(MenuRepository.class),applicationContext.getBean(BackendApiRepository.class));
    }

    static ConfigurableApplicationContext applicationContext;

    public static void main(String[] args) throws UnknownHostException {
        SpringApplication app = new SpringApplication(UserCenterApp.class);
        DefaultProfileUtil.addDefaultProfile(app);
        applicationContext = app.run(args);

        // 后初始化
        postInit();
}

大功告成！