Configure a JAAS custom login module for Liberty

We can configure a custom Java Authentication and Authorization Service (JAAS) login module before or after configuring the Liberty server login module.

Liberty supports the server.xml file, client.xml file, and the JAAS configuration file for JAAS configuration. However, it is suggested to configure the JAAS custom login module in the server.xml file or client.xml file.

See Configure an application JAAS custom login context entry and login module using a JAAS configuration file for Liberty.

Make sure we have a JAR file containing the JAAS custom login module, which implements the javax.security.auth.spi.LoginModule interface as described in Develop JAAS custom login modules for a system login configuration. In that topic, JAAS custom login module uses hashtable, callbacks, or shared state variables provided by the Liberty server to pass authentication data to the system login module.

We can use a custom login module to either make additional authentication decisions or add information to the subject to make finer-grained authorization decisions inside the application.

See JAAS configuration and JAAS login modules for a more detailed overview.

We can also use the developer tools to configure a custom JAAS login module.

See Configure JAAS on Liberty using developer tools. There are several security configuration examples on the Open Liberty website for reference when configuring security for the applications on Liberty.

To configure a JAAS custom login module, complete the following steps:

1. Enable the Liberty Application Security feature, version 2.0 or later, in the server.xml file.

   <featureManager>
       <feature>appSecurity-2.0</feature>
   </featureManager>
   

2. Create a class com.sample.CustomLoginModule that implements the LoginModule interface and package it into the CustomLoginModule.jar file.

3. Create a <library> element that uses a <fileset> element that indicates where the CustomLoginModule.jar file is. In this example, the library id is customLoginLib.

   <library id="customLoginLib">
       <fileset dir="${server.config.dir}" includes="CustomLoginModule.jar"/>
   </library> 

4. Create a <jaasLoginModule> element. In this example, the id is myCustom.

   1. Configure the custom login module to require a successful authentication by setting the controlFlag attribute to REQUIRED.
   2. Set the libraryRef attribute to customLoginLib, the id of the <library> element configured in the previous step. This login module also has two options: UserRegistry is ldap and mapToUser is user1.

   <jaasLoginModule id="myCustom" 
            className="com.sample.CustomLoginModule" 
            controlFlag="REQUIRED" libraryRef="customLoginLib">
       <options UserRegistry="ldap" mapToUser="user1"/>
   </jaasLoginModule>

   Note: The option name cannot start with a period (.), config., or service and must be unique. Also, the property name id or ID is not allowed.

5. Create a <jaasLogincontextEntry> element with an id and a unique name of the system-defined JAAS configuration: system.WEB_INBOUND. We can also set this JAAS configuration to system.DEFAULT, WSLogin, or our own JAAS configuration. On the loginModuleRef attribute, add myCustom, the id of the jaasLoginModule element created in the previous step. Putting this id first in the list means that it is the first JAAS login module to be called. We must also list the other default login modules: hashtable , userNameAndPassword , certificate , and token .

   <jaasLoginContextEntry id="system.WEB_INBOUND" name="system.WEB_INBOUND" 
            loginModuleRef="myCustom, hashtable, userNameAndPassword, certificate, token"  />
   

   For more information about the <jaasLoginContextEntry>, <jaasLoginModule>, <options>, and <library> elements, see Application Security 2.0.