Configuring inbound identity mapping

 

Overview

For inbound identity mapping, it is recommend that you write a custom login module and configure WebSphere Application Server to run the login module first within the system login configurations. Consider the following steps when you write your custom login module:

1. Get the inbound user identity from the callbacks and map the identity, if necessary.This step occurs in the login method of the login module. A valid authentication has either or both of the following callbacks present: NameCallback and the WSCredTokenCallback. The following code sample shows you how to determine the user identity:

   javax.security.auth.callback.Callback callbacks[] = 
      new javax.security.auth.callback.Callback[3];
   	callbacks[0] = new javax.security.auth.callback.NameCallback("");
   	callbacks[1] = new javax.security.auth.callback.PasswordCallback
        ("Password: ", false);
   	callbacks[2] = new com.ibm.websphere.security.auth.callback.
        WSCredTokenCallbackImpl("");
   	callbacks[3] = new com.ibm.wsspi.security.auth.callback.
        WSTokenHolderCallback("");
   
   	try
   	{
   		callbackHandler.handle(callbacks);
   	} 
   	catch (Exception e)
   	{
   		// Handles exceptions
   		throw new WSLoginFailedException (e.getMessage(), e);
   	}
   
   	// Shows which callbacks contain information
   	boolean identitySwitched = false;
   	String uid = ((NameCallback) callbacks[0]).getName();
   	char password[] = ((PasswordCallback) callbacks[1]).getPassword();
   	byte[] credToken = ((WSCredTokenCallbackImpl) callbacks[2]).getCredToken();
   	java.util.List authzTokenList = ((WSTokenHolderCallback) 
        callbacks[3]).getTokenHolderList();
   
   	if (credToken != null)
   	{
   		try
   		{
   			String uniqueID = WSSecurityPropagationHelper.validateLTPAToken(credToken);
   			String realm = WSSecurityPropagationHelper.getRealmFromUniqueID (uniqueID);
          // Now set the string to the UID so that you can use the result for either
          // mapping or logging in.
   			uid = WSSecurityPropagationHelper.getUserFromUniqueID (uniqueID);
   		}
   		catch (Exception e)
   		{
   			// Handles the exception
   		}	
   	}
   	else if (uid == null)
   	{
        // Throws an exception if invalid authentication data exists.
        // You must have either UID or CredToken
   		throw new WSLoginFailedException("invalid authentication data.");
   	}
   	else if (uid != null && password != null)
   	{
        // This is a typical authentication. You can choose to map this ID to  
        // another ID or you can skip it and allow WebSphere Application Server 
        // to log in for you. When passwords are presented, be very careful to not 
        // validate the password because this is the initial authentication.
   		
   		return true;
   	}
   
       // If desired, map this uid to something else and set the identitySwitched 
       // boolean. If the identity was changed, clear the propagated attributes 
       // below so they are not used incorrectly.
   	uid = myCustomMappingRoutine (uid);
   	
       // Clear the propagated attributes because they no longer applicable to the 
       // new identity
   	if (identitySwitched)
   	{
   		((WSTokenHolderCallback) callbacks[3]).setTokenHolderList(null);
   	}
   

2. Check to see if attribute propagation occurred and if the attributes for the user are already present when the identity remains the same. Check to see if the user attributes are already present from the sending server to avoid duplicate calls to the user registry lookup. To check for the user attributes, use a method on the WSTokenHolderCallback callback that analyzes the information present in the callback. Determine if the information is sufficient for WebSphere Application Server to create a Subject. The following code sample checks for the user attributes:

   boolean requiresLogin = 
   ((com.ibm.wsspi.security.auth.callback.WSTokenHolderCallback) 
   callbacks[2]).requiresLogin();

   If sufficient attributes are not present to form the WSCredential and WSPrincipal objects that are needed to perform authorization, the previous code sample returns a true result. When the result is false, you can choose to discontinue processing as the necessary information exists to create the Subject without performing additional remote user registry calls.

3. (Optional)   Look up the required attributes from the user registry, put the attributes in a hashtable, and add the hashtable to the shared state.If the identity is switched in this login module, complete the following steps:

   1. Create the hashtable of attributes as shown in the following example.

   2. Add the hashtable to the shared state.
   If the identity is not switched, but the value of the requiresLogin code sample shown previously is true, you can create the hashtable of attributes. However, you are not required to create a hashtable in this situation because WebSphere Application Server handles the login for you. However, you might consider creating a hashtable to gather attributes in special cases where you use your own special user registry. Creating a UserRegistry implementation, using a hashtable, and letting WebSphere Application Server gather the user attributes for you might be the easiest solution. The following table shows how to create a hashtable of user attributes:

   if (requiresLogin || identitySwitched)
   	{
   		// Retrieves the default InitialContext for this server.
   		javax.naming.InitialContext ctx = new javax.naming.InitialContext();
   
   		// Retrieves the local UserRegistry implementation.
   		com.ibm.websphere.security.UserRegistry reg = (com.ibm.websphere.
           security.UserRegistry) 
   		ctx.lookup("UserRegistry");				
   
        // Retrieves the user registry uniqueID based on the uid specified
        // in the NameCallback.
   		String uniqueid = reg.getUniqueUserId(uid);
   	 	uid = WSSecurityPropagationHelper.getUserFromUniqueID (uniqueID);
   			
        // Retrieves the display name from the user registry based on the uniqueID.
   		String securityName = reg.getUserSecurityName(uid);
   	
        // Retrieves the groups associated with the uniqueID.
   		java.util.List groupList = reg.getUniqueGroupIds(uid);
   			
        // Creates the java.util.Hashtable with the information that you gathered 
        // from the UserRegistry implementation.
   		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 a cache key that is used as part of the lookup mechanism for 
        // the created Subject. The cache key can be an object, but should have 
        // an implemented toString() method. Make sure that the cacheKey contains 
        // enough information to scope it to the user and any additional attributes 
        // that you are using. If you do not specify this property the Subject is 
        // scoped to the returned WSCREDENTIAL_UNIQUEID, by default.
   		hashtable.put(com.ibm.wsspi.security.token.AttributeNameConstants.
           WSCREDENTIAL_CACHE_KEY, "myCustomAttribute" + uniqueid);
   		// Adds the hashtable to the sharedState of the Subject.
   		_sharedState.put(com.ibm.wsspi.security.token.AttributeNameConstants.
           WSCREDENTIAL_PROPERTIES_KEY, hashtable);
   	}
   

   The following rules define in more detail how a hashtable login is performed. You must use a java.util.Hashtable object in either the Subject (public or private credential set) or in a shared state HashMap. The com.ibm.wsspi.security.token.AttributeNameConstants class defines the keys that contain the user information. If the hashtable object is put into the shared state of the login context using a custom login module that is listed prior to the Lightweight Third Party Authentication (LTPA) login module, the value of the java.util.Hashtable object is searched using the following key within the hashMap shared state:

   Property

   com.ibm.wsspi.security.cred.propertiesObject

   Reference to the property

   AttributeNameConstants.WSCREDENTIAL_PROPERTIES_KEY

   Explanation

   This key searches for the hashtable object that contains the required properties in the sharedState of the login context.

   Expected result

   A java.util.Hashtable object.

   If a java.util.Hashtable object is found either inside the Subject or within the sharedState area, verify that the following properties are present in the hashtable:

   Property

   com.ibm.wsspi.security.cred.uniqueId

   Reference to the property

   AttributeNameConstants.WSCREDENTIAL_UNIQUEID

   Returns

   java.util.String

   Explanation

   The value of the property must be a unique representation of the user. For the WebSphere Application Server default implementation, this property represents the information that is stored in the application authorization table. The information is located in the application deployment descriptor after it is deployed and the user-to-role mapping is performed.

   See the expected format examples if the user-to- role mapping is performed using a lookup to a WebSphere Application Server user registry implementation. If a third-party authorization provider overrides the user-to-role mapping, then the third-party authorization provider defines the format. To ensure compatibility with the WebSphere Application Server default implementation for the unique ID value, call the WebSphere Application Server public String getUniqueUserId(String userSecurityName) UserRegistry method.

   Expected format examples

   Realm	Format (uniqueUserId)
   Lightweight Directory Access Protocol (LDAP)	ldaphost.austin.ibm.com:389/cn=user,o=ibm,c=us
   Windows	MYWINHOST/S-1-5-21-963918322-163748893-4247568029-500
   Linux and UNIX	MYUNIXHOST/32

   
   
   

   The com.ibm.wsspi.security.cred.uniqueId property is required.

   Property

   com.ibm.wsspi.security.cred.securityName

   Reference to the property

   AttributeNameConstants. WSCREDENTIAL_ SECURITYNAME

   Returns

   java.util.String

   Explanation

   This property searches for the securityName of the authentication user. This name is commonly called the display name or short name. WebSphere Application Server uses the securityName attribute for the getRemoteUser, getUserPrincipal and getCallerPrincipal application programming interfaces (APIs). To ensure compatibility with the WebSphere Application Server default implementation for the securityName value, call the WebSphere Application Server public String getUserSecurityName(String uniqueUserId) UserRegistry method.

   Expected format examples

   Realm	Format (uniqueUserId)
   LDAP	user (LDAP UID)
   Windows	user (Windows username)
   Linux and UNIX	user (Linux or UNIX username)

   
   
   

   The com.ibm.wsspi.security.cred.securityName property is required.

   Property

   com.ibm.wsspi.security.cred.groups

   Reference to the property

   AttributeNameConstants. WSCREDENTIAL_GROUPS

   Returns

   java.util.ArrayList

   Explanation

   This key searches for the ArrayList of groups to which the user belongs. The groups are specified in the realm_name/user_name format. The format of these groups is important because the groups are used by the WebSphere Application Server authorization engine for group-to-role mappings in the deployment descriptor. The format provided must match the format that is expected by the WebSphere Application Server default implementation. When you use a third-party authorization provider, use the format expected by the third-party provider. To ensure compatibility with the WebSphere Application Server default implementation for the unique group IDs value, call the WebSphere Application Server public List getUniqueGroupIds(String uniqueUserId) UserRegistry method.

   Expected format examples for each group in the ArrayList

   Realm	Format
   LDAP	ldap1.austin.ibm.com:389/cn=group1,o=ibm,c=us
   Windows	MYWINREALM/S-1-5-32-544
   Linux and UNIX	MY/S-1-5-32-544

   
   
   

   The com.ibm.wsspi.security.cred.groups property is not required. A user is not required to have associated groups.

   Property

   com.ibm.wsspi.security.cred.cacheKey

   Reference to the property

   AttributeNameConstants. WSCREDENTIAL_CACHE_KEY

   Returns

   java.lang.Object

   Explanation

   This key property can specify an Object that represents the unique properties of the login that includes the user-specific information and the user dynamic attributes that might affect uniqueness. For example, when the user logs in from location A, which might affect their access control, the cacheKey needs to include location A so that the Subject received is the correct Subject for the current location.

   This com.ibm.wsspi.security.cred.cacheKey property is not required. When this property is not specified, the cache lookup is the value that is specified for WSCREDENTIAL_UNIQUEID. When this information is found in the java.util.Hashtable object, WebSphere Application Server creates a Subject similar to the Subject that goes through the normal login process (at least for LTPA). The new Subject contains a WSCredential object and a WSPrincipal object that is fully populated with the information that is found in the Hashtable object.

4. Add your custom login module into the RMI_INBOUND, WEB_INBOUND, and DEFAULT Java Authentication and Authorization Service (JAAS) system login configurations.Configure the RMI_INBOUND login configuration so that WebSphere Application Server loads your new custom login module first.

   1. Click Security > JAAS Configuration > System logins > RMI_INBOUND.

   2. Under Additional Properties, click JAAS login modules > New to add your login module to the RMI_INBOUND configuration.

   3. Return to the JAAS login modules panel for RMI_INBOUND and click Set order to change the order that the login modules are loaded so that WebSphere Application Server loads your custom login module first.

   4. Repeat the previous three steps for the WEB_INBOUND and DEFAULT login configurations.

 

Results

This process configures identity mapping for an inbound request.

 

Example

Example: Custom login module for inbound mapping

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Managing security

Custom login module development for a system login configuration
Example: Custom login module for inbound mapping
    

 

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