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聊聊spring security的permitAll以及webIgnore

@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {
    @Override
    public void configure(HttpSecurity http) throws Exception {
        http
                .authorizeRequests()
                .antMatchers("/css/**", "/js/**","/fonts/**").permitAll()
                .anyRequest().authenticated();
    }
}

web ignore配置实例

@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {
    @Override
    public void configure(WebSecurity web) throws Exception {
        web.ignoring().antMatchers("/css/**");
        web.ignoring().antMatchers("/js/**");
        web.ignoring().antMatchers("/fonts/**");
    }
}

二者区别

顾名思义，WebSecurity主要是配置跟web资源相关的，比如css、js、images等等，但是这个还不是本质的区别，关键的区别如下：

ingore是完全绕过了spring security的所有filter，相当于不走spring security
permitall没有绕过spring security，其中包含了登录的以及匿名的。

AnonymousAuthenticationFilter

spring-security-web-4.2.3.RELEASE-sources.jar!/org/springframework/security/web/authentication/AnonymousAuthenticationFilter.java

/**
 * Detects if there is no {@code Authentication} object in the
 * {@code SecurityContextHolder}, and populates it with one if needed.
 *
 * @author Ben Alex
 * @author Luke Taylor
 */
public class AnonymousAuthenticationFilter extends GenericFilterBean implements
        InitializingBean {
    //......
    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
            throws IOException, ServletException {

        if (SecurityContextHolder.getContext().getAuthentication() == null) {
            SecurityContextHolder.getContext().setAuthentication(
                    createAuthentication((HttpServletRequest) req));

            if (logger.isDebugEnabled()) {
                logger.debug("Populated SecurityContextHolder with anonymous token: '"
                        + SecurityContextHolder.getContext().getAuthentication() + "'");
            }
        }
        else {
            if (logger.isDebugEnabled()) {
                logger.debug("SecurityContextHolder not populated with anonymous token, as it already contained: '"
                        + SecurityContextHolder.getContext().getAuthentication() + "'");
            }
        }

        chain.doFilter(req, res);
    }

    protected Authentication createAuthentication(HttpServletRequest request) {
        AnonymousAuthenticationToken auth = new AnonymousAuthenticationToken(key,
                principal, authorities);
        auth.setDetails(authenticationDetailsSource.buildDetails(request));

        return auth;
    }

    //......
}

这个filter的主要功能就是给没有登陆的用户，填充AnonymousAuthenticationToken到SecurityContextHolder的Authentication，后续依赖Authentication的代码可以统一处理。

FilterComparator

spring-security-config-4.1.4.RELEASE-sources.jar!/org/springframework/security/config/annotation/web/builders/FilterComparator.java

final class FilterComparator implements Comparator<Filter>, Serializable {
    private static final int STEP = 100;
    private Map<String, Integer> filterToOrder = new HashMap<String, Integer>();

    FilterComparator() {
        int order = 100;
        put(ChannelProcessingFilter.class, order);
        order += STEP;
        put(ConcurrentSessionFilter.class, order);
        order += STEP;
        put(WebAsyncManagerIntegrationFilter.class, order);
        order += STEP;
        put(SecurityContextPersistenceFilter.class, order);
        order += STEP;
        put(HeaderWriterFilter.class, order);
        order += STEP;
        put(CorsFilter.class, order);
        order += STEP;
        put(CsrfFilter.class, order);
        order += STEP;
        put(LogoutFilter.class, order);
        order += STEP;
        put(X509AuthenticationFilter.class, order);
        order += STEP;
        put(AbstractPreAuthenticatedProcessingFilter.class, order);
        order += STEP;
        filterToOrder.put("org.springframework.security.cas.web.CasAuthenticationFilter",
                order);
        order += STEP;
        put(UsernamePasswordAuthenticationFilter.class, order);
        order += STEP;
        put(ConcurrentSessionFilter.class, order);
        order += STEP;
        filterToOrder.put(
                "org.springframework.security.openid.OpenIDAuthenticationFilter", order);
        order += STEP;
        put(DefaultLoginPageGeneratingFilter.class, order);
        order += STEP;
        put(ConcurrentSessionFilter.class, order);
        order += STEP;
        put(DigestAuthenticationFilter.class, order);
        order += STEP;
        put(BasicAuthenticationFilter.class, order);
        order += STEP;
        put(RequestCacheAwareFilter.class, order);
        order += STEP;
        put(SecurityContextHolderAwareRequestFilter.class, order);
        order += STEP;
        put(JaasApiIntegrationFilter.class, order);
        order += STEP;
        put(RememberMeAuthenticationFilter.class, order);
        order += STEP;
        put(AnonymousAuthenticationFilter.class, order);
        order += STEP;
        put(SessionManagementFilter.class, order);
        order += STEP;
        put(ExceptionTranslationFilter.class, order);
        order += STEP;
        put(FilterSecurityInterceptor.class, order);
        order += STEP;
        put(SwitchUserFilter.class, order);
    }

    //......
}

这个类定义了spring security内置的filter的优先级，AnonymousAuthenticationFilter在倒数第五个执行，在FilterSecurityInterceptor这个类之前。

FilterSecurityInterceptor

spring-security-web-4.2.3.RELEASE-sources.jar!/org/springframework/security/web/access/intercept/FilterSecurityInterceptor.java

/**
 * Performs security handling of HTTP resources via a filter implementation.
 * <p>
 * The <code>SecurityMetadataSource</code> required by this security interceptor is of
 * type {@link FilterInvocationSecurityMetadataSource}.
 * <p>
 * Refer to {@link AbstractSecurityInterceptor} for details on the workflow.
 * </p>
 *
 * @author Ben Alex
 * @author Rob Winch
 */
public class FilterSecurityInterceptor extends AbstractSecurityInterceptor implements
        Filter {
    //......
}

这个相当于spring security的核心处理类了，它继承抽象类AbstractSecurityInterceptor

spring-security-core-4.2.3.RELEASE-sources.jar!/org/springframework/security/access/intercept/AbstractSecurityInterceptor.java

public abstract class AbstractSecurityInterceptor implements InitializingBean,
        ApplicationEventPublisherAware, MessageSourceAware {
    //......
    protected InterceptorStatusToken beforeInvocation(Object object) {
        Assert.notNull(object, "Object was null");
        final boolean debug = logger.isDebugEnabled();

        if (!getSecureObjectClass().isAssignableFrom(object.getClass())) {
            throw new IllegalArgumentException(
                    "Security invocation attempted for object "
                            + object.getClass().getName()
                            + " but AbstractSecurityInterceptor only configured to support secure objects of type: "
                            + getSecureObjectClass());
        }

        Collection<ConfigAttribute> attributes = this.obtainSecurityMetadataSource()
                .getAttributes(object);

        if (attributes == null || attributes.isEmpty()) {
            if (rejectPublicInvocations) {
                throw new IllegalArgumentException(
                        "Secure object invocation "
                                + object
                                + " was denied as public invocations are not allowed via this interceptor. "
                                + "This indicates a configuration error because the "
                                + "rejectPublicInvocations property is set to 'true'");
            }

            if (debug) {
                logger.debug("Public object - authentication not attempted");
            }

            publishEvent(new PublicInvocationEvent(object));

            return null; // no further work post-invocation
        }

        if (debug) {
            logger.debug("Secure object: " + object + "; Attributes: " + attributes);
        }

        if (SecurityContextHolder.getContext().getAuthentication() == null) {
            credentialsNotFound(messages.getMessage(
                    "AbstractSecurityInterceptor.authenticationNotFound",
                    "An Authentication object was not found in the SecurityContext"),
                    object, attributes);
        }

        Authentication authenticated = authenticateIfRequired();

        // Attempt authorization
        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);
        }
    }
    //......
}

主要的逻辑在这个beforeInvocation方法，它就依赖了authentication

private Authentication authenticateIfRequired() {
        Authentication authentication = SecurityContextHolder.getContext()
                .getAuthentication();

        if (authentication.isAuthenticated() && !alwaysReauthenticate) {
            if (logger.isDebugEnabled()) {
                logger.debug("Previously Authenticated: " + authentication);
            }

            return authentication;
        }

        authentication = authenticationManager.authenticate(authentication);

        // We don't authenticated.setAuthentication(true), because each provider should do
        // that
        if (logger.isDebugEnabled()) {
            logger.debug("Successfully Authenticated: " + authentication);
        }

        SecurityContextHolder.getContext().setAuthentication(authentication);

        return authentication;
    }

这个方法判断authentication如果是已经校验过的，则返回；没有校验过的话，则调用authenticationManager进行鉴权。

而AnonymousAuthenticationFilter设置的authentication在这个时候就派上用场了

spring-security-core-4.2.3.RELEASE-sources.jar!/org/springframework/security/authentication/AnonymousAuthenticationToken.java

```

public class AnonymousAuthenticationToken extends AbstractAuthenticationToken implements

Serializable {

private AnonymousAuthenticationToken(Integer keyHash, Object principal,

Collection<? extends GrantedAuthority> authorities) {

super(authorities);

if (principal == null || "".equals(principal)) {
        throw new IllegalArgumentException("principal cannot be null or empty");
    }
    Assert.notEmpty(authorities, "authorities cannot be null or empty");

    this.keyHash = keyHash;
    this.principal = principal;
    setAuthenticated(true);
}
//......

}

```

它默认就是authenticated

小结

web ignore比较适合配置前端相关的静态资源，它是完全绕过spring security的所有filter的；
而permitAll，会给没有登录的用户适配一个AnonymousAuthenticationToken，设置到SecurityContextHolder，方便后面的filter可以统一处理authentication。