Category: cas

Like Alfresco in the cloud and myriad other systems we’ve decided to use the email address as the user name for logging in. This works fine until you want to allow the user to be able to change their email.

The problem here is that Alfresco doesn’t support changing user names (I believe that it can be done with some database hacking but not recommended)

My solution here is to allow logging in via CAS to use the mail attribute as the user name but to pass the uid to Alfresco to use as the Alfresco user name while this means that the Alfresco user name is not the same as they’ve used to log in, it does allow you to change the mail attribute and as the user name isn’t often visible this works quite well – actually it’s not too bad to set the uid as the mail address especially if the rate of change is low although there are some situations where this is potentially confusing.

So how to do it…

First configure CAS (I’m using 4.0_RC2 at the moment)

In your deployerConfigContext.xml find your registeredServices and add

 <property name="usernameAttribute" value="uid"/>

so you end up with something like this:

<bean class="org.jasig.cas.services.RegexRegisteredService" p:id="0"
	p:name="HTTP and IMAP" p:description="Allows HTTP(S) and IMAP(S) protocols"
	p:serviceId="^(https?|imaps?)://alfresco.wrighting.org/.*" p:evaluationOrder="10000001">
    <property name="usernameAttribute" value="uid"/>
</bean>

For 4.1 you’ll need:

Note that you need the allowedAttributes to contain the usernameAttribute otherwise the value of the usernameAttribute will be ignored.

<bean class="org.jasig.cas.services.RegexRegisteredService" p:id="0"
p:serviceId="^(https?|imaps?)://xxx.*"
p:evaluationOrder="10000000">
<property name="usernameAttributeProvider">
<bean
class="org.jasig.cas.services.PrincipalAttributeRegisteredServiceUsernameProvider"
c:usernameAttribute="uid" />
</property>
<property name="attributeReleasePolicy">
<bean class="org.jasig.cas.services.ReturnAllowedAttributeReleasePolicy">
<property name="allowedAttributes">
<list>
<value>uid</value>
</list>
</property>
</bean>
</property>
</bean>

Now to configure Share and Alfresco (see previous posts)

If you are using CAS 4.0_RC2 then make sure that you are using the CAS 2 protocol (or SAML but I’d go with CAS 2) so if you are using the java client the in the web.xml your CAS Validation Filter will be:

  <filter>
   <filter-name>CAS Validation Filter</filter-name>
   <filter-class>org.jasig.cas.client.validation.Cas20ProxyReceivingTicketValidationFilter</filter-class>
   <init-param>
       <param-name>casServerUrlPrefix</param-name>
        <param-value>${cas.server.prefix}</param-value>
   </init-param>
     <init-param>
         <param-name>serverName</param-name>
         <param-value>${alfresco.server.name}</param-value>
     </init-param>
 </filter>

(This will work for CAS 1 in later versions)

Lots of confusion around on this subject so I’m going to attempt to distill some wisdom into this post and tweak it for Ubuntu

2 good blogs Nick with mod_auth_cas and Martin with CAS client and the Alfresco docs

I’m not going to talk about setting up CAS here as this post is complex enough already – I’ll just say be careful if using self signed certs.

I’ve used Martin’s method before with Alfresco 3.4

It’s a tricky decision as to which approach to use:

• the mod_auth_cas approach is the approach supported by Alfresco but it introduces the Apache plug in which isn’t as well supported by CAS and you have problems with managing the mod_auth_cas cookie management, caching etc
• the java client is a bit more involved and intrusive but seems to work quite well in the end
• I haven’t tried container managed auth but it looks promising

Using mod_auth_cas

For a more detailed explanation look at Nick’s blog – this entry is more about how rather than why and is specific to using apt-get packages on Ubuntu.

First set up your mod_auth_cas

Next tell Tomcat to trust the Apache authentication by setting the following attribute tomcatAuthentication=”false” on the AJP Connector (port 8009)

Now you need to set up the Apache Tomcat Connectors module – mod-jk

apt-get install libapache2-mod-jk


Edit the properties file defined in /etc/apache2/mods-enables/jk.conf – /etc/libapache2-mod-jk/workers.properties – to set the following values

workers.tomcat_home=/opt/alfresco-4.2.c/tomcat
workers.java_home=/opt/alfresco-4.2.c/java
Add to your sites file e.g. /etc/apache2/sites-enabled/000-default

JkMount /alfresco ajp13_worker
JkMount /alfresco/* ajp13_worker
JkMount /share ajp13_worker
JkMount /share/* ajp13_worker

And don’t forget to tell Apache which URLs to check

<Location />
Authtype CAS
require valid-user
</Location>

A more complex example in the wiki here

Add the following to tomcat/shared/classes/alfresco-global.properties

authentication.chain=external-apache:external,alfrescoNtlm1:alfrescoNtlm
external.authentication.enabled=true
external.authentication.proxyHeader=X-Alfresco-Remote-User
external.authentication.proxyUserName=


Finally add the following section to tomcat/shared/classes/alfresco/web-extension/share-config-custom.xml

Note that if you have customizations you may need this in the share-config-custom.xml in your jar

 	<config evaluator="string-compare" condition="Remote">
		<remote>
			<endpoint>
				<id>alfresco-noauth</id>
				<name>Alfresco - unauthenticated access</name>
				<description>Access to Alfresco Repository WebScripts that do not
					require authentication
				</description>
				<connector-id>alfresco</connector-id>
				<endpoint-url>http://localhost:8080/alfresco/s</endpoint-url>
				<identity>none</identity>
			</endpoint>

			<endpoint>
				<id>alfresco</id>
				<name>Alfresco - user access</name>
				<description>Access to Alfresco Repository WebScripts that require
					user authentication
				</description>
				<connector-id>alfresco</connector-id>
				<endpoint-url>http://localhost:8080/alfresco/s</endpoint-url>
				<identity>user</identity>
			</endpoint>

			<endpoint>
				<id>alfresco-feed</id>
				<name>Alfresco Feed</name>
				<description>Alfresco Feed - supports basic HTTP authentication via
					the EndPointProxyServlet
				</description>
				<connector-id>http</connector-id>
				<endpoint-url>http://localhost:8080/alfresco/s</endpoint-url>
				<basic-auth>true</basic-auth>
				<identity>user</identity>
                                <external-auth>true</external-auth>
			</endpoint>

			<endpoint>
				<id>activiti-admin</id>
				<name>Activiti Admin UI - user access</name>
				<description>Access to Activiti Admin UI, that requires user
					authentication
				</description>
				<connector-id>activiti-admin-connector</connector-id>
				<endpoint-url>http://localhost:8080/alfresco/activiti-admin
				</endpoint-url>
				<identity>user</identity>
			</endpoint>
		</remote>
	</config>

 

This gets you logged in but you still need to logout! Share CAS logout.
One thing to be careful about with using mod_auth_cas here is that you need to be aware of the mod_auth_cas caching – if you are not careful you’ll log out but mod_auth_cas will still think that you are logged in. There are some options here – set the cache timeout to be low (inefficient), use single sign out (experimental)

Using CAS java client

Martin’s blog works for Alfresco 3.4 and here are some notes I made for 4.2.d

Note that it is not supported to make changes to the web.xml

Make the following jars available:

cas-client-core-3.2.1.jar, commons-logging-1.1.1.jar, commons-logging-api-1.1.1.jar

You can do this by including them in the wars or by copying the following jars into <<alfresco home>>/tomcat/lib
N.B. If you place them into the endorsed directory then you will get error messages like this:
SEVERE: Exception starting filter CAS java.lang.NoClassDefFoundError: javax/servlet/Filter


You need to make the same changes to tomcat/shared/classes/alfresco-global.properties and share-config-custom.xml as for the mod_auth_cas method

Now add the following to share/WEB-INF/web.xml and alfresco/WEB-INF/web.xml

There’s some fine tuning to do on the url-pattern probably the best way is to copy the filter mappings for the existing authentication filter and add /page for share and /faces for alfresco.

Using the values below works but is a little crude (shown here to be concise)

 <filter>
    <filter-name>CAS Authentication Filter</filter-name>
    <filter-class>org.jasig.cas.client.authentication.AuthenticationFilter
    </filter-class>
    <init-param>
        <param-name>casServerLoginUrl</param-name>
        <param-value>https://www.wrighting.org/sso/login</param-value>
    </init-param>
    <init-param>
        <param-name>serverName</param-name>
        <param-value>https://alfresco.wrighting.org</param-value>
    </init-param>
</filter>
<filter>
    <filter-name>CAS Validation Filter</filter-name>
    <filter-class>org.jasig.cas.client.validation.Cas10TicketValidationFilter
    </filter-class>
    <init-param>
        <param-name>casServerUrlPrefix</param-name>
        <param-value>https://www.wrighting.org/sso</param-value>
    </init-param>
    <init-param>
        <param-name>serverName</param-name>
        <param-value>https://alfresco.wrighting.org</param-value>
    </init-param>
</filter>
<filter>
    <filter-name>CAS HttpServletRequest Wrapper Filter</filter-name>
    <filter-class>org.jasig.cas.client.util.HttpServletRequestWrapperFilter
    </filter-class>
</filter>
<filter-mapping>
    <filter-name>CAS Authentication Filter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>
<filter-mapping>
    <filter-name>CAS Validation Filter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>
<filter-mapping>
    <filter-name>CAS HttpServletRequest Wrapper Filter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

Next add the following to the session-config section of the web.xml which relates to this issue which may be solved via removing the jsessionid from the url (this may cause problems with the flash uploader if you’re still using it see here)

<tracking-mode>COOKIE</tracking-mode>

There’s also a case for using web-fragments to avoid changing the main web.xml

You will need to redirect the change password link in the header (how to depends on version)

Container managed auth

This looks quite interesting CAS Tomcat container auth as it allows the use of the CAS java client within tomcat so being closer to the mod_auth_cas approach but without needing to configure Apache.

This issue referenced above gives some details of how somebody tried it – I think it should work if the session tracking mode is set to COOKIE but haven’t tried it.

More complex configurations

This is beyond what I’m trying to do but if you’ve got a load balanced configuration you may need to think about the session management – the easiest way to approach may be to use sticky sessions e.g.

ProxyRequests Off
ProxyPassReverse /share balancer://app
ProxyPass /share balancer://app stickysession=JSESSIONID|jsessionid nofailover=On

BalancerMember ajp://localhost:8019/share route=tomcat3
BalancerMember ajp://localhost:8024/share route=tomcat4

 

Update – since surf 1.2 (at least) the Surf LogoutController understands the redirectURL request parameter (and redirectURLQueryKey, redirectURLQueryValue) which makes this all unnecessary – add the parameters to the end of the dologout call in the header – how depends on the version of Share – in share-config-custom.xml for the old style header – see  here for the new style header

I’ve finally had the time to work out how to configure Alfresco Share to successfully log out when using CAS to log in.

If you log out of just CAS you will still be logged into Share and vice versa so you need to log out of both – and just for good measure log out of Alfresco at the same time.

This follows on from Martin Bergljung’s blog on configuring for CAS

(Note this doesn’t do anything about single sign out as that’s a different problem)

The way I’ve done this is to override the logoutController by defined a new java class and referencing it in custom-slingshot-application-context.xml

 <!-- Override Logout Controller - to expire Alfresco tickets -->
   <bean id="logoutController" class="org.wrighting.web.site.servlet.CASSlingshotLogoutController">
      <property name="cacheSeconds" value="-1" />
      <property name="useExpiresHeader"><value>true</value></property>
      <property name="useCacheControlHeader"><value>true</value></property>
      <property name="connectorService" ref="connector.service" />
      <!-- if blank assumes the same as Share -->

      <property name="casHost"><value>https://alfresco</value></property>
      <property name="casPath"><value>sso/logout</value></property>

   </bean>

You’ll see here that I’ve defined a couple to properties to indicate where the CAS log out page lies – this is where the user will be redirected when they log out. This fits quite closely with the method of configuring the CAS server in the web.xml but you could use an alternative approach such as properties.

The java code is very closely based on org.alfresco.web.site.servlet.SlingshotLogoutController however there is one significant difference in that it doesn’t call handleRequestInternal in LogoutController.
This is because LogoutController.handleRequestInternal ends up redirecting to request.getContextPath whereas we want to go to our CAS logout page however it’s still necessary to make sure that you call AuthenticationUtil.logout which would normally be done in the LogoutController.

package org.wrighting.web.site.servlet;

import java.net.URL;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.extensions.surf.UserFactory;
import org.springframework.extensions.surf.mvc.LogoutController;
import org.springframework.extensions.surf.site.AuthenticationUtil;
import org.springframework.extensions.surf.support.AlfrescoUserFactory;
import org.springframework.extensions.webscripts.connector.AlfrescoAuthenticator;
import org.springframework.extensions.webscripts.connector.Connector;
import org.springframework.extensions.webscripts.connector.ConnectorContext;
import org.springframework.extensions.webscripts.connector.ConnectorService;
import org.springframework.extensions.webscripts.connector.HttpMethod;
import org.springframework.extensions.webscripts.connector.Response;
import org.springframework.web.servlet.ModelAndView;

/**
 * CAS specific override of the Share specific override of the SpringSurf
 * dologout controller.
 * <p>
 * The implementation ensures Alfresco tickets are removed if appropriate and as
 * it can't delegates to the SpringSurf implementation for framework cleanup
 * does that clean up and then sends a logout to the CAS host
 *
 * @see org.alfresco.web.site.servlet.SlingshotLogoutController
 *
 * @author Ian Wright
 */
public class CASSlingshotLogoutController extends LogoutController {
    private static Log logger = LogFactory
            .getLog(CASSlingshotLogoutController.class);
    private ConnectorService connectorService;
    private String casHost;
    private String casPath;

    /**
     * @param connectorService
     *            the ConnectorService to set
     */
    public void setConnectorService(ConnectorService connectorService) {
        this.connectorService = connectorService;
    }

    @Override
    public ModelAndView handleRequestInternal(HttpServletRequest request,
            HttpServletResponse response) throws Exception {

        try {
            HttpSession session = request.getSession(false);
            if (session != null) {
                // retrieve the current user ID from the session
                String userId = (String) session
                        .getAttribute(UserFactory.SESSION_ATTRIBUTE_KEY_USER_ID);

                if (userId != null) {
                    // get the ticket from the Alfresco connector
                    Connector connector = connectorService.getConnector(
                            AlfrescoUserFactory.ALFRESCO_ENDPOINT_ID, userId,
                            session);
                    String ticket = connector.getConnectorSession()
                            .getParameter(
                                    AlfrescoAuthenticator.CS_PARAM_ALF_TICKET);

                    if (ticket != null) {
                        // if we found a ticket, then expire it via REST API -
                        // not all auth will have a ticket i.e. SSO
                        Response res = connector.call("/api/login/ticket/"
                                + ticket, new ConnectorContext(
                                HttpMethod.DELETE));
                        if (logger.isDebugEnabled())
                            logger.debug("Expired ticket: " + ticket
                                    + " user: " + userId + " - status: "
                                    + res.getStatus().getCode());
                    }
                }
            }
        } finally {
            AuthenticationUtil.logout(request, response);
            String target = request.getContextPath();
            if (casHost != null && casHost.length() > 0) {
                target = casHost;
            } else {
                URL reconstructedURL = new URL(request.getScheme(),
                        request.getServerName(),
                        request.getServerPort(),
                        "");
                target = reconstructedURL.toExternalForm();
            }
            if (casPath != null && casPath.length() > 0) {
                target += '/' + casPath;
            }
            if (logger.isDebugEnabled()) {
                logger.debug("Logout to:" + target);
            }
            response.sendRedirect(target);
        }

        return null;
    }

    /**
     * @param casHostValue
     *            the casHost to set - defaults to the same as Share
     */
    public void setCasHost(String casHostValue) {
        casHost = casHostValue;
    }

    /**
     * @param casPathValue
     *            the location of the CAS logout servlet
     */
    public void setCasPath(String casPathValue) {
        casPath = casPathValue;
    }
}

 

Having successfully configured Alfresco (and Share) to authenticate using CAS – it’s documented here

The next challenge is to try and work out how to get this authentication working with webdav
Update:

One way to do this this is to bypass CAS and authenticate against the underlying CAS datastore directly by adding a new authentication component.

Of course this means that you are not using CAS but then as you are likely to be accessing WebDAV outside of the browser the single sign on capabilities are not particularly relevant

We use Drupal as our underlying CAS data store so there’s a bit of custom code here – you may be able to just configure the authentication chain if you’re using a different method e.g. LDAP

So in alfresco-global.properties add to the authentication chain:
authentication.chain=cas:external,localDrupal:drupal

While you’re there set up some database connection properties e.g.

drupal.db.driver=org.gjt.mm.mysql.Driver
drupal.db.username=drupal
drupal.db.password=drupal
drupal.db.url=jdbc:mysql://localhost:3306/drupal6

I’m not going to cover ensuring that you have access to the mysql database here. If it’s on a different machine you’ll need to configure MySQL as well as any firewall rules.

Next it’s time to tell Alfresco about the new component that you are creating so create the directory alfresco/subsystems/Authentication/drupal and add the following files:

drupal-authentication-context.xml

<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xmlns="http://www.springframework.org/schema/beans" 
xsi:schemalocation="http://www.springframework.org/schema/beans  
  http://www.springframework.org/schema/beans/spring-beans-2.0.xsd">

    <bean class="org.apache.commons.dbcp.BasicDataSource" 
                       destroy-method="close" id="drupalDataSource">
       <property name="driverClassName" value="${drupal.db.driver}"/>
        <property name="url" value="${drupal.db.url}"/>
        <property name="username" value="${drupal.db.username}"/>
        <property name="password" value="${drupal.db.password}"/>
        <property name="validationQuery" value="SELECT 1"/>
        <property name="testOnBorrow" value="true"/>
        <property name="defaultAutoCommit" value="false"/>
        <property name="maxWait" value="5000"/>
    </bean>

    <bean class="mypackage.authentication.DrupalAuthenticationComponentImpl" 
id="drupalAuthenticationComponent" parent="authenticationComponentBase"> 
<property name="dataSource" ref="drupalDataSource"/>
        <property name="nodeService">
            <ref bean="nodeService"/>
        </property>
        <property name="personService">
            <ref bean="personService"/>
        </property>
        <property name="transactionService">
            <ref bean="transactionService"/>
        </property>
</bean>

      <!-- Wrapped Drupal authentication component to be used within subsystem -->
    <bean id="AuthenticationComponent">
        <property name="proxyInterfaces">
            <value>org.alfresco.repo.security.authentication.AuthenticationComponent</value>
        </property>
        <property name="transactionManager">
            <ref bean="transactionManager"/>
        </property>
        <property name="target">
            <ref bean="drupalAuthenticationComponent"/>
        </property>
        <property name="transactionAttributes">
            <props>
                <prop key="*">${server.transaction.mode.default}</prop>
            </props>
        </property>
    </bean>
     <!-- Authentication service for authentication component chaining

     Note. the id of this bean must be 'localAuthenticationService' for it to
     be picked up, as an authentication service, by the
     Subsystem Chaining Authentication Service
    -->
    <bean id="localAuthenticationService">
        <property name="ticketComponent">
            <ref bean="ticketComponent"/>
        </property>
        <property name="authenticationComponent">
            <ref bean="drupalAuthenticationComponent"/>
        </property>
        <property name="sysAdminParams">
            <ref bean="sysAdminParams"/>
        </property>
    </bean>
</beans>

 

drupal-authentication.properties

drupal.db.driver=org.gjt.mm.mysql.Driver
drupal.db.username=drupal
drupal.db.password=drupal
drupal.db.url=jdbc:mysql://localhost:3306/drupal6

 

Then create the bean that is referenced from the config

package mypackage.cms.authentication;

import org.alfresco.repo.management.subsystems.ActivateableBean;
import org.alfresco.repo.security.authentication.AbstractAuthenticationComponent;
import org.alfresco.repo.security.authentication.AuthenticationException;
import org.apache.commons.codec.digest.DigestUtils;
import org.apache.commons.lang.StringUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.dao.DataAccessException;
import org.springframework.jdbc.core.JdbcTemplate;

import javax.sql.DataSource;
import java.security.MessageDigest;

/**
 * Authenticates a user by Drupal.
 * <p/>
 * The authentication is done against the database table USERS and the
 * column NAME (username) and column PASS (MD5 password)
 * <p/>
 * Tested with Drupal 6
 *
 * @author martin.bergljung@ixxus.co.uk
 */
public class DrupalAuthenticationComponentImpl 
extends AbstractAuthenticationComponent implements ActivateableBean {
    public static final String GET_USER_PWD_SQL = "SELECT pass FROM users WHERE name=?";

    private final Log logger = LogFactory.getLog(getClass());

    /**
     * Spring JDBC template used to query or update a JDBC data source
     */
    private JdbcTemplate m_jdbcTemplate;

    /**
     * Is this bean active? I.e. should this part of the subsystem be used?
     */
    private boolean m_active = true;

    public DrupalAuthenticationComponentImpl() {
        super();
    }

    /**
     * Controls whether this bean is active. I.e. should this part of the subsystem be used?
     *
     * @param active <code>true</code> if this bean is active
     */
    public void setActive(boolean active) {
        m_active = active;
    }

    /**
     * Dependeny Injects the data source to be used for querying Drupal database
     *
     * @param dataSource the data source to use
     */
    public void setDataSource(DataSource dataSource) {
        m_jdbcTemplate = new JdbcTemplate(dataSource);
    }

    /*
    * (non-Javadoc)
    * @see org.alfresco.repo.management.subsystems.ActivateableBean#isActive()
    */
    public boolean isActive() {
        return m_active;
    }

    /**
     * Authenticate against the Drupal database
     *
     * @param userName the username to authenticate
     * @param password the password to authenticate (passed in as plain text)
     * @throws AuthenticationException if authentication failed
     */
    @Override
    protected void authenticateImpl(String userName, char[] password) throws AuthenticationException {
        String userPwd = new String(password);

        // Generate an MD5 hash for the password as that is what we get back from Drupal
        // Get the value as hex
        String userPwdMd5 = DigestUtils.md5Hex(userPwd);

        if (logger.isDebugEnabled()) {
            logger.debug("About to authenticate user: " + userName + " with MD5 password: " + userPwdMd5);
        }

        try {
            String drupalPwdMd5 = m_jdbcTemplate.queryForObject(GET_USER_PWD_SQL, new Object[]{userName}, String.class);

            if (logger.isDebugEnabled()) {
                logger.debug("Got MD5 password from Drupal database: " + drupalPwdMd5);
            }

            if (StringUtils.isNotBlank(drupalPwdMd5)) {
                if (MessageDigest.isEqual(userPwdMd5.getBytes(), drupalPwdMd5.getBytes())) {
                    // Authentication has been successful.
                    // Set the current user, they are now authenticated.
                    setCurrentUser(userName);
                } else {
                    throw new AuthenticationException("Access denied for user: " + userName +
                            ", incorrect password provided.");
                }
            } else {
                throw new AuthenticationException(
                        "Password in Drupal database is blank, empty, or null for user: " + userName);
            }
        } catch (DataAccessException dae) {
            throw new AuthenticationException(
                    "Error getting password from Drupal database for user: " + userName +
                            ", user may not exist in the Drupal database", dae);
        }
    }

    @Override
    protected boolean implementationAllowsGuestLogin() {
        return true;
    }
}