WebSphere Application Server Version 6.1 Feature Pack for Web Services
             Operating Systems: z/OS

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This topic applies only on the z/OS operating system.

Custom one to one LDAP to System Authorization Facility (SAF) mapping modules

You can customize Java Authentication and Authorization (JAAS) login configurations by writing a customized login mapping module.

WebSphere Application Server for z/OS has the ability to provide mapping from a remote method invocation (RMI) inbound request with LDAP credentials to the system authorization facility (SAF) Identity. The use case is a WebSphere Application Server on any platform that is configured to LDAP and sends a RMI/IIOP request to a second server configured to a SAF User Registry. The WebSphere Application Server (release 5.1 and higher) sends a RMI request using LTPA Token representing the LDAP identity to the WebSphere Application Server for z/OS that is configured to SAF. The following figure illustrates this mapping.


Figure 1. Mapping from RMI inbound request with LDAP credentials to SAF Identity

The sample below is a JAAS RMI inbound login module that opens the LTPA token, extracts the LDAP userid, strips the cn=userID, and sets the WSCredential to the SAF userid. The sample inbound login module that is configured to the second server is only supported on WebSphere Application Server for z/OS release 6.1 and higher.

The sample is really a hash login module in which the com.ibm.wsspi.security.token.AttributeNameConstants.WSCREDENTIAL_UNIQUEID is set to the desired z/OS SAF Identity. TheltpaLoginModule checks for a com.ibm.wsspi.security.token.AttributeNameConstants.WSCREDENTIAL_UNIQUEID that has been passed and uses the ID specified to build the appropriate security context for the user.

This sample module is configured as a RMI_INBOUND JAAS login module and must be specified at the top of the list followed by the ltpaLoginModule.

In the following sample, a Java 2 Platform, Enterprise Edition (J2EE) identity is available to control the mapping to a SAF identity. The sample uses the hash login of Constants.WSCREDENTIAL value in the shared state.

The following is a sample SampleLTPASAFMappingModule:
// This program may be used, executed, copied, modified and
// distributed without royalty for the purpose of developing,
// using, marketing, or distributing.
//
//

package com.ibm.websphere.security;

import com.ibm.websphere.security.auth.CredentialDestroyedException;
import com.ibm.websphere.security.auth.WSPrincipal;
import com.ibm.websphere.security.cred.WSCredential;
import com.ibm.wsspi.security.auth.callback.Constants;
import com.ibm.wsspi.security.token.AttributeNameConstants;
import java.lang.reflect.Array;
import java.util.Map;
import javax.security.auth.Subject;
import javax.security.auth.callback.CallbackHandler;
import javax.security.auth.login.CredentialExpiredException;
import javax.security.auth.login.LoginException;
import javax.security.auth.spi.LoginModule;
import com.ibm.wsspi.security.token.WSSecurityPropagationHelper;
import com.ibm.websphere.security.auth.callback.WSCredTokenCallbackImpl;
import com.ibm.websphere.security.auth.WSLoginFailedException;

/**
 * **
 * SampleLTPASAFMappingModule demonstrates a custom login module
 * that maps the existing LTPA Token from the shared state to a UNIQUE ID to avoid the Login. Typical use is a inbound LTPA Token generated from a different realm (perhaps a non zOS Realm) into a SAF User Registry. The LTPA Token is used as the trusted identity token. 
 *
 * ***
 *
 * @author IBM Corporation
 * @version 1.0
 * @since 1.0
 */
public class SampleLTPASAFMappingModule implements LoginModule
{
    /*
     * **
     * Constant that represents the name of this mapping module.  Whenever this sample
     * code is used to create a class with a different name, this value should be changed.
     *
     * By default, this value is used as part of the sample audit token, and for debugging
     * purposes.
     * ***
     */
    private final static String MAPPING_MODULE_NAME = "com.ibm.websphere.security.SampleLTPASAFMappingModule";

    private final static int MAXIMUM_NAME_LENGTH = 8;

    /*
     * **
     * Specifies whether debugging is enabled for this Login Module.  This depends on the
     * value of the "debug" option passed in from the LoginContext.
     * ***
     */
    private boolean debugEnabled = false;
 /*
     * **
     * Specifies the inbound realm that this Login Module is to handle.  If there is no incoming 
     * property setting for onlyThisRealm, then this Login module will process all inbound
     * request regardless of the incoming idenity realm within the LTPA token. 
     * ***
     */
    private String onlyThisRealm = null;

    /*
     * **
     * Stores the Subject passed from the LoginContext.
     * ***
     */
    private Subject subject;

    /*
     * **
     * Stores the CallbackHandler passed from the LoginContext.
     * ***
     */
    private CallbackHandler callbackHandler;

    /*
     * **
     * Stores the shared state Map passed from the LoginContext.
     * ***
     */
    private Map sharedState;

    /*
     * **
     * Stores the options Map passed from the LoginContext.
     * ***
     */
    private Map options;

    /*
     * **
     * This value is used to store the success or failure of the login() method so
     * that commit() and abort() can act differently in the two cases if so desired.
     * ***
     */
    private boolean succeeded = false;

    /**
     * **Construct an uninitialized mapping module object.***
     */
    public SampleLTPASAFMappingModule()
    {
    }

    /**
     * **Initialize this login module.***
     *
     * **
     * This is called by the LoginContext after this login module is
     * instantiated. The relevant information is passed from the LoginContext
     * to this login module. If the login module does not understand any of the data
     * stored in the sharedState and options parameters,
     * they can be ignored.
     * ***
     *
     * @param subject
     *                The subject that this LoginContext is authenticating
     * @param callbackHandler
     *                A CallbackHandler for communicating with the end user to gather login information (e.g., username and password).
     * @param sharedState
     *                The state shared with other configured login modules.
     * @param options
     *                The options specified in the login configuration for this particular login module.
     */
    public void initialize(Subject newSubject, CallbackHandler newCallbackHandler, Map newSharedState, Map newOptions)
    {
        // obtain the value for debug before anything else so that tracing can be used within
        // this method
        if (newOptions.containsKey("debug"))
        {
            String debugEnabledString = (String) newOptions.get("debug");
            if (debugEnabledString != null && debugEnabledString.toLowerCase().equals("true"))
            {
                debugEnabled = true;
            }
        }
	if (debugEnabled)
        {
            debug("initialize() entry");
        }
	// obtain the value for realm before anything else to see if this login module should 
	// only process a particular inbound realm or if it should process all realm. A null value 
	// singles all realms will be processed. 
	if (newOptions.containsKey("realm"))
        {
            onlyThisRealm = (String) newOptions.get("realm");
	    onlyThisRealm = onlyThisRealm.trim();
	}


        // this login module is not going to use any of these objects except for the sharedState,
        // but for consistency with most login modules, we will save a reference to all of them
        this.subject = newSubject;
        this.callbackHandler = newCallbackHandler;
        this.sharedState = newSharedState;
        this.options = newOptions;

        if (debugEnabled)
        {
            debug(new Object[] { "initialize() exit", subject, callbackHandler, sharedState, options });
        }
    }

    /**
     *
     * @return true if the authentication succeeded, or false
     *         if this Login Module should be ignored
     * @exception LoginException
     *         if the authentication fails, which is impossible for this Login Module
     */
    public boolean login() throws LoginException
    {
        if (debugEnabled)
        {
            debug("login() entry");
        }

	// Handle the callback 
	javax.security.auth.callback.Callback callbacks[] = 
            new javax.security.auth.callback.Callback[1];
	callbacks[0] = new com.ibm.websphere.security.auth.callback.WSCredTokenCallbackImpl("");

	try
	{
		callbackHandler.handle(callbacks);
	} 
	catch (Exception e)
	{
	     if (debugEnabled)
             {
                 debug(new Object[] { "Caught exception in callbackhandler: ", e });
             }
             return false;
	} 
	
	byte[] credToken = ((WSCredTokenCallbackImpl) callbacks[0]).getCredToken();
        String uid = null;
	String realm = null;
	String uniqueID = null;

	//This routine will only process a LTPA token. If there is no inbound token, 
	//then this routine will return true and allow the other LM should handle
	//this request
	if (credToken != null)
	{
		try
		{
			uniqueID = WSSecurityPropagationHelper.validateLTPAToken(credToken);
			realm = WSSecurityPropagationHelper.getRealmFromUniqueID (uniqueID);
                        uid = createSAFIdenityName (uniqueID);
			if (debugEnabled)
                        {
                            debug("using uniqueID: "+ uniqueID+ " inbound realm: "+ realm +
				  "uid: " + uid );
                        }
		}
		catch (Exception e)
		{
		   if (debugEnabled)
                   {
                       debug(new Object[] { "Caught exception in callbackhandler: ", e });
                   }
                   return false;
		}	
	}
	else return true; // let the other LM handle this request. 
	

	//onlyThisRealm is a input property setting to see if we want this login module
	//to handle only 1 inputed realm request. If onlyThisRealm is null, 
	//then we will process all request and continue on. If the onlyThisRealm does
	//not match the inbound request extracted from LTPA, then we will let the other
	//LM handle this request. 
	//
	if ((onlyThisRealm != null) && (!realm.trim().equals(onlyThisRealm))) {
            if (debugEnabled)
            {
                debug("inbound realm of "+realm+" does not match option realm of "+onlyThisRealm);
            }
            return true;
	}

	try {
	    // Retrieves the default InitialContext for this server.
	    javax.naming.InitialContext ctx = new javax.naming.InitialContext();

	    // Retrieves the local UserRegistry object.
	    com.ibm.websphere.security.UserRegistry reg = 
		    (com.ibm.websphere.security.UserRegistry) ctx.lookup("UserRegistry");				

	
  	   // Retrieves the registry uniqueID based on the uid that is specified 
           // in the NameCallback.
	   String uniqueid = reg.getUniqueUserId(uid);
	   if (debugEnabled)
            {
                debug("uniqueid "+uniqueid);
            }
	   // Retrieves the display name from the user registry based on the uniqueID.
	   String securityName = reg.getUserSecurityName(uid);
	   if (debugEnabled)
            {
                debug("securityName "+securityName);
            }
	
	   // Retrieves the groups associated with this uniqueID.
	   java.util.List groupList = reg.getUniqueGroupIds(uid);

   	   // Creates the java.util.Hashtable with the information that you gathered 
           // from the UserRegistry.
	   // By setting this hashtable, the LTPA login module will propertly
	   // setup the SAF Identity. 
   	   java.util.Hashtable hashtable = new java.util.Hashtable();
           hashtable.put(com.ibm.wsspi.security.token.AttributeNameConstants.
              WSCREDENTIAL_UNIQUEID, uniqueid);		   
           hashtable.put(com.ibm.wsspi.security.token.AttributeNameConstants.
              WSCREDENTIAL_SECURITYNAME, securityName);
	   hashtable.put(com.ibm.wsspi.security.token.AttributeNameConstants.
              WSCREDENTIAL_GROUPS, groupList);

	   // Adds the hashtable to the shared state of the Subject.
	   sharedState.put(com.ibm.wsspi.security.token.AttributeNameConstants.
              WSCREDENTIAL_PROPERTIES_KEY, hashtable);
        }
	catch (Exception e)
	{
	   if (debugEnabled)
           {
               debug(new Object[] { "Caught exception in callbackhandler: ", e });
           }
	   WSLoginFailedException e2 = new WSLoginFailedException("SampleLTPASAFMappingModule detected an error. "+e);
           throw e2;
        }		
        if (debugEnabled)
        {
            debug("login() exit");
        }
        return succeeded;
    }

    /**
     * **Method to commit the authentication result.***
     *
     * **
     * This Login Module does not need to commit any data, so we will simply return.
     * ***
     *
     * @return true if the original login succeeded, or false
     *         if the original login failed
     * @exception LoginException
     *         if the commit fails, which cannot happen in this Login Module
     */
    public boolean commit() throws LoginException
    {
        if (debugEnabled)
        {
            debug("commit() entry");
        }

        // the return value of commit() is the same as the success of the original login
        boolean returnVal = succeeded;

        cleanup();

        if (debugEnabled)
        {
            debug("commit() exit");
        }
        return returnVal;
    }

    /**
     * **Method to abort the authentication process (Phase 2).***
     *
     * **
     * No matter whether our original login succeeded or failed, this method cleans up
     * our state and returns.
     * ***
     *
     * @return true if the original login succeeded, or false
     *         if the original login failed
     * @exception LoginException
     *         if the abort fails, which cannot happen in this Login Module
     */
    public boolean abort() throws LoginException
    {
        if (debugEnabled)
        {
            debug("abort() entry");
        }

        // the return value of abort() is the same as the success of the original login
        boolean returnVal = succeeded;

        cleanup();

        if (debugEnabled)
        {
            debug("abort() exit");
        }
        return returnVal;
    }

    /**
     * **Method which logs out a Subject.***
     *
     * **
     * Since our commit method did not modify the Subject, we don't have anything to
     * logout or clean up and can just return true.
     * ***
     *
     * @return true if the logout succeeded
     * @exception LoginException
     *         if the logout fails, which cannot happen in the Login Module
     */
    public boolean logout() throws LoginException
    {
        if (debugEnabled)
        {
            debug("logout() entry");
        }

        // our local variables were cleanup up during the commit, so no further cleanup is needed

        if (debugEnabled)
        {
            debug("logout() exit");
        }

        // since there is nothing to logout, we always succeed
        return true;
    }

    /*
     * **
     * Cleans up our local variables; the only cleanup required for
     * this Login Module is to set our success variable back to false.
     * ***
     */
    private void cleanup()
    {
        if (debugEnabled)
        {
            debug("cleanup() entry");
        }

        // there's nothing to cleanup, really, so just reset our success variable
        succeeded = false;

        if (debugEnabled)
        {
            debug("cleanup() exit");
        }
    }

    /*
     * **
     * Private method to print trace information.  This implementation uses System.out
     * to print trace information to standard output, but a custom tracing system can
     * be implemented here as well.
     * ***
     */
    private void debug(Object o)
    {
        System.out.println("Debug: " + MAPPING_MODULE_NAME);
        if (o != null)
        {
            if (o.getClass().isArray())
            {
                int length = Array.getLength(o);
                for (int i = 0; i < length; i++)
                {
                    System.out.println("\t" + Array.get(o, i));
                }
            }
            else
            {
                System.out.println("\t" + o);
            }
        }
    }
    /*
     * **
     * TODO
     * Private method to generate the SAF Idenity from the LDAP identity. This routine may
     * need to be modify by your installation standards to extract the SAF Idenity from
     * the LDAP IDentity. OR this routine could be written to map the LDAP to SAF identity.
     * ***
     */
    private String createSAFIdenityName(String name)
    {
        if (debugEnabled)
        {
            debug("createSAFIdenityName() entry");
        }

        if (debugEnabled)
        {
            debug("Using name='" + name + "' from principal");
        }

        name = name.toUpperCase();
        int index = name.indexOf("/") + 1; // index of the first character after the first /
        System.out.println(index);
        System.out.println(name);
        if (index >= name.length())
        {
            // this block handles the case where the first / is the last character in the String,
            // it really shouldn't happen, but if it does we can just strip it off
            name = name.substring(0, index - 1);

            if (debugEnabled)
            {
                debug("Stripping trailing / from name");
            }
        }
        else
        {
            // index is either 0 (if no / exists in the name), or it is the position
            // after the first / in the name
            //
            // either way, we will take the substring from that point until the end of the string
            name = name.substring(index);
        }
        System.out.println(name);
        
        if (name.indexOf("CN=") >= 0) 
        	name = name.substring((name.indexOf("CN=")+3),name.length());
        
        
        if (name.indexOf(",") > 0)
            name = name.substring(0,name.indexOf(","));
        
        // shorten the name if its length exceeds the defined maximum
        if (name.length() > MAXIMUM_NAME_LENGTH)
        {
            name = name.substring(0, MAXIMUM_NAME_LENGTH);

            if (debugEnabled)
            {
                debug("WSPrincipal name shortened to " + name);
            }
        }

        if (debugEnabled)
        {
            debug("createSAFIdenityName() exit");
        }
        return name; //return a SAF Idenity Name
    }
}

The sample mapping module creates a mapping from an RMI inbound request with LDAP credentials to SAF identity. This module can be customized to perform the mapping.




Related tasks
Writing a custom System Authorization Facility (SAF) mapping module with non-local operating system
Installing and configuring a custom System Authorization Facility mapping module for WebSphere Application Server
Developing custom login modules for a system login configuration
Developing programmatic logins with the Java Authentication and Authorization Service
Concept topic    

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Last updated: Nov 25, 2008 2:35:59 AM CST
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