一般来说, Web 应用的安全性包括用户认证( Authentication )和用户授权( Authorization )两个部分。用户认证指的是验证某个用户是否为系统中的合法主体,也就是说用户能否访问该系统。用户授权指的是验证某个用户是否有权限执行某个操作。在一 个系统中,不同用户所具有的权限是不同的。比如对一个文件来说,有的用户只能进行读取,而有的用户可以进行修改。一般来说,系统会为不同的用户分配不同的 角色,而每个角色则对应一系列的权限。
对于上面提到的两种应用情景, Spring Security 框架都有很好的支持。在用户认证方面, Spring Security 框架支持主流的认证方式,包括 HTTP 基本认证、 HTTP 表单验证、 HTTP 摘要认证、 OpenID 和 LDAP 等。在用户授权方面, Spring Security 提供了基于角色的访问控制和访问控制列表( Access Control List , ACL ),可以对应用中的领域对象进行细粒度的控制。
若 Spring Security 整合 CAS 单点登录 , 使用 CAS 进行认证和获取授权信息 , 使用 Spring Security 验证权限 ,则可以很好的把公共的认证和授权与具体应用剥离开来,同时简化应用的配置。本文就 Spring Security 与 CAS 的整合进行说明。
一 、基本需求
1. jdk 5.0
2. tomcat 6
3. Spring 3.0.5.RELEASE
4. Spring Security 3.1.0.RELEASE
5. CAS cas-server-3.4.7, cas-client-3.2.0
6. 使用http协议进行传输
7. 通过jdbc进行用户验证,需要通过casserver提供除登录用户名以外的附加信息(用于Spring Security 进行验证权限)
二、搭建CAS Server
1. 把从 http://www.jasig.org/cas/download 上下载cas解压找到
cas-server-3.4.7-releasecas-server-3.4.7modulescas-server-webapp-3.4.7.war
, 解压cas-server-webapp-3.4.7.war ,部署在至tomcat上端口为 8080的server上,如部署路径为
http://localhost:8080/cas 。为了达到需求目的,我们主要需要对
/WEB-INF/deployerConfigContext.xml 文件进行修改。
2.
使用
jdbc
数据源进行用户认证,需要修改
deployerConfigContext.xml
的
authenticationHandlers
方式
<property name="
authenticationHandlers
">
<list>
<!--
| This is the authentication handler that authenticates services by means of callback via SSL, thereby validating
| a server side SSL certificate.
+-->
<bean class="org.jasig.cas.authentication.handler.support.HttpBasedServiceCredentialsAuthenticationHandler"
p:httpClient-ref="httpClient" />
<!--
| This is the authentication handler declaration that every CAS deployer will need to change before deploying CAS
| into production. The default SimpleTestUsernamePasswordAuthenticationHandler authenticates UsernamePasswordCredentials
| where the username equals the password. You will need to replace this with an AuthenticationHandler that implements your
| local authentication strategy. You might accomplish this by coding a new such handler and declaring
| edu.someschool.its.cas.MySpecialHandler here, or you might use one of the handlers provided in the adaptors modules.
+-->
//
注释掉,否则只要用户名和密码一致的话都可以得到认证
<!-- bean class="org.jasig.cas.authentication.handler.support.SimpleTestUsernamePasswordAuthenticationHandler" / -->
//
数据库认证方式
<!--DATABASE -- >
<bean class="org.jasig.cas.adaptors.jdbc.QueryDatabaseAuthenticationHandler">
<property name="dataSource" ref="dataSource" />
<property name="sql" value="select password from t_admin_user where login_name=?" />
</bean>
</list>
<property name="authenticationHandlers">
<!-- DATABASE
增加数据源配置
-->
<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName"><value>com.mysql.jdbc.Driver</value></property>
<property
name="url"><value>jdbc:mysql:///cas?useUnicode=true&characterEncoding=utf-8</value></property>
<property name="username"><value>root</value></property>
</bean>
3.
通过
casserver
提供除登录用户名以外的附加信息(用于
Spring Security
进行验证权限),修改
/WEB-INF/
deployerConfigContext
.xml
3.1
修改
credentialsToPrincipalResolvers
<property name="credentialsToPrincipalResolvers">
<list>
<bean class="org.jasig.cas.authentication.principal.UsernamePasswordCredentialsToPrincipalResolver" >
<property name="attributeRepository" ref="attributeRepository" /> //
增加此属性,为认证过的用户的
Principal
添加属性
</bean>
<bean class="org.jasig.cas.authentication.principal.HttpBasedServiceCredentialsToPrincipalResolver" />
</list>
</property>
3.2
修改该文件中默认的
attributeRepositorybean
配置
<!--
使用
SingleRowJdbcPersonAttributeDao
获取更多用户的信息
-->
<bean id="attributeRepository" class="org.jasig.services.persondir.support.jdbc.SingleRowJdbcPersonAttributeDao">
<constructor-arg index="0" ref="dataSource"/>
<constructor-arg index="1" value="select role_name,group_name from role where login_name = ?"/>
<!--
这里的
key
需写
username,value
对应数据库用户名字段
-->
<property name="queryAttributeMapping">
<map>
<entry key="username" value="login_name"/>
</map>
</property>
<!--key
对应数据库字段,
value
对应客户端获取参数
-->
<property name="resultAttributeMapping">
<map>
<entry key="role_name" value="authorities"/> //
这个从数据库中获取的角色,用于在应用中
security
的权限验证
</map>
</property>
</bean>
3.3
修改该文件中最默认的
serviceRegistryDao
中的属性全部注释掉
这个
bean
中的
RegisteredServiceImpl
的
ignoreAttributes
属性将决定是否添加
attributes
属性内容,默认为
false:
不添加,只有去掉这个配置,
cas server
才会将获取的用户的附加属性添加到认证用的
Principal
的
attributes
中去。
<bean id="serviceRegistryDao" class="org.jasig.cas.services.InMemoryServiceRegistryDaoImpl"></bean>
3.4
若采用
CAS
的
Cas20ServiceTicketValidator
认证,则需要修改
WEB-INFviewjspprotocol2.0casServiceValidationSuccess.jsp
文件,才能把获取的属性传递至客户端
<%@ page session="false" %>
<%@ taglib prefix="c" uri="
http://java.sun.com/jsp/jstl/core
" %>
<%@ taglib uri="
http://java.sun.com/jsp/jstl/functions
" prefix="fn" %>
<cas:serviceResponse xmlns:cas=\'http://www.yale.edu/tp/cas\'>
<cas:authenticationSuccess>
<cas:user>${fn:escapeXml(assertion.chainedAuthentications[fn:length(assertion.chainedAuthentications)-1].principal.id)}</cas:user>
<c:if test="${not empty pgtIou}">
<cas:proxyGrantingTicket>${pgtIou}</cas:proxyGrantingTicket>
</c:if>
<c:if test="${fn:length(assertion.chainedAuthentications) > 1}">
<cas:proxies>
<c:forEach var="proxy" items="${assertion.chainedAuthentications}"
varStatus="loopStatus" begin="0"
end="${fn:length(assertion.chainedAuthentications)-2}" step="1">
<cas:proxy>${fn:escapeXml(proxy.principal.id)}</cas:proxy>
</c:forEach>
</cas:proxies>
</c:if>
<!--
增加如下内容
-->
<c:if
test="${fn:length(assertion.chainedAuthentications[fn:length(assertion.chainedAuthentications)-1].principal.attributes)>
0}">
<cas:attributes>
<c:forEach
var="attr"
items="${assertion.chainedAuthentications[fn:length(assertion.chainedAuthentications)-1].principal.attributes}"
varStatus="loopStatus"
begin="0"
end="${fn:length(assertion.chainedAuthentications[fn:length(assertion.chainedAuthentications)-1].principal.attributes)-1}"
step="1">
<cas:${fn:escapeXml(attr.key)}>${fn:escapeXml(attr.value)}</cas:${fn:escapeXml(attr.key)}>
</c:forEach>
</cas:attributes>
</c:if>
</cas:authenticationSuccess>
</cas:serviceResponse>
至此,
CAS Server
搭建完毕。
三、搭建
CAS Client
(即
Spring Security
)应用
1. CAS Client
下需要把
spring-security-cas-3.1.0.M2.jar
等
Spring Security
相关的
jar
引入,把
cas-client-core-3.2.0.jar
引入,用于从
cas server
上获取相关认证与授权信息。
2. CAS Client
应用的
web.xml
,
增加如下
<!--
spring
配置文件
-
->
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:applicationContext-security-ns.xml</param-value>
</context-param>
<!-- spring security filter -->
<filter>
<filter-name>springSecurityFilterChain</filter-name>
<filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
</filter>
<filter-mapping>
<filter-name>springSecurityFilterChain</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<!-- spring
默认侦听器
-->
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
3. spring security
文件的配置
applicationContext-security-ns.xml
<?xml version="1.0"?>
<beans xmlns="
http://www.springframework.org/schema/beans
"
xmlns:security="
http://www.springframework.org/schema/security
"
xmlns:xsi="
http://www.w3.org/2001/XMLSchema-instance
"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/security
http://www.springframework.org/schema/security/spring-security-3.1.xsd
">
<!--
Enable security, let the casAuthenticationEntryPoint handle all intercepted urls.
The CAS_FILTER needs to be in the right position within the filter chain.
-->
<security:http entry-point-ref="casAuthenticationEntryPoint" auto-config="true">
<security:intercept-url pattern="/**" access="ROLE_USER"></security:intercept-url>
<security:custom-filter position="CAS_FILTER" ref="casAuthenticationFilter"></security:custom-filter>
</security:http>
<!--
Required for the casProcessingFilter, so define it explicitly set and
specify an Id Even though the authenticationManager is created by
default when namespace based config is used.
-->
<security:authentication-manager alias="authenticationManager">
<security:authentication-provider ref="casAuthenticationProvider"></security:authentication-provider>
</security:authentication-manager>
<!--
This section is used to configure CAS. The service is the
actual redirect that will be triggered after the CAS login sequence.
-->
<bean id="serviceProperties" class="org.springframework.security.cas.ServiceProperties">
//http://localhost:8088/SpringSecurity
具体应用
// j_spring_cas_security_check spring
的虚拟
URL
,此标志标识使用
CAS authentication upon return from CAS SSO login.
<property name="service" value="
http://localhost:8088/SpringSecurity/j_spring_cas_security_check"></property
>
<property name="sendRenew" value="false"></property>
</bean>
<!--
The CAS filter handles the redirect from the CAS server and starts the ticket validation.
-->
<bean id="casAuthenticationFilter" class="org.springframework.security.cas.web.CasAuthenticationFilter">
<property name="authenticationManager" ref="authenticationManager"></property>
</bean>
<!--
The entryPoint intercepts all the CAS authentication requests.
It redirects to the CAS loginUrl for the CAS login page.
-->
<bean id="casAuthenticationEntryPoint" class="org.springframework.security.cas.web.CasAuthenticationEntryPoint">
<property name="loginUrl" value="
http://localhost:8080/cas/login"></property
> //SSO
登录地址
<property name="serviceProperties" ref="serviceProperties"></property>
</bean>
<!--
Handles the CAS ticket processing.
-->
<bean id="casAuthenticationProvider" class="org.springframework.security.cas.authentication.CasAuthenticationProvider">
<property name="authenticationUserDetailsService" ref="authenticationUserDetailsService"/>
<property name="serviceProperties" ref="serviceProperties"></property>
<property name="ticketValidator">
<bean class="org.jasig.cas.client.validation.Cas20ServiceTicketValidator">
<constructor-arg index="0" value="
http://localhost:8080/cas
" /> //SSO
验证地址
</bean>
</property>
<property name="key" value="cas"></property>
</bean>
<!-- authorities
对应
CAS server
的
登录属性,
在此设置到
spirng security
中,用于
spring security
的验证
-->
<bean id="authenticationUserDetailsService"
class="org.springframework.security.cas.userdetails.GrantedAuthorityFromAssertionAttributesUserDetailsService">
<constructor-arg>
<array>
<value>authorities</value>
</array>
</constructor-arg>
</bean>
</beans>
至此,
CAS
客户端搭建完毕。
四、总结
通过上述的配置,则具体应用在使用的时候,用户认证和授权则无需过问,只需在应用中配置相关的角色访问权限即可。即,只需对下面的红色部分进行修改,即可以完成应用的认证和授权工作。大大简化了应用和认证与授权的剥离工作
<security:http entry-point-ref="casAuthenticationEntryPoint" auto-config="true">
<security:intercept-url pattern="/**" access="ROLE_USER"></security:intercept-url>
<security:custom-filter position="CAS_FILTER" ref="casAuthenticationFilter"></security:custom-filter>
</security:http>
五、扩展
若在同一
SSO
下有多个应用,
同一户在不同应用下有不同的角色
,则考虑扩展获取用户权限的环节;资源和角色在数据库中进行配置等等。