This document describes how to add an object into the Subject from a login module and describes other infrastructure considerations to make sure that the Java object gets propagated.
Prior to completing this task, verify that security propagation is enabled in the administrative console.
About this task With security attribute propagation enabled, you can propagate data either horizontally with single sign-on (SSO) enabled or downstream using Common Secure Interoperability Version 2 (CSIv2). When a login occurs, either through an application login configuration or a system login configuration, a custom login module can be plugged in to add Java serialized objects into the Subject during login. This document describes how to add an object into the Subject from a login module and describes other infrastructure considerations to make sure that the Java object gets propagated.
After a custom Java object is added into the Subject, WebSphere Application Server serializes the object on the sending server, deserializes the object on the receiving server, and adds the object back into the Subject downstream. However, some requirements exist for this process to occur successfully. For more information on the JAAS programming model, see the JAAS information provided in Security: Resources for learning .
Important: Whenever you plug a custom login module into the login infrastructure of WebSphere Application Server, make sure that the code is trusted. When you add the login module into the install_root/classes directory, the login module has Java 2 Security AllPermissions permissions . IBM recommends that you add your login module and other infrastructure classes into any private directory. However, modify the install_root/properties/server.policy file to make sure that your private directory, Java archive (JAR) file, or both have the permissions required to run the application programming interfaces (API) that are called from the login module. Because the login module might be run after the application code on the call stack, you might add doPrivileged code so that you do not need to add additional properties to your applications.
The following code sample shows how to add doPrivileged code. For information on what to do during initialization, login and commit, see Custom login module development for a system login configuration.
public customLoginModule()
{
public void initialize(Subject subject, CallbackHandler callbackHandler,
Map sharedState, Map options)
{
}
public boolean login() throws LoginException
{
// Construct callback for the WSTokenHolderCallback so that you
// can determine if // your custom object has propagated Callback callbacks[] = new Callback[1];
callbacks[0] = new WSTokenHolderCallback("Authz Token List: ");
try {
_callbackHandler.handle(callbacks);
}
catch (Exception e)
{
throw new LoginException (e.getLocalizedMessage());
}
// Checks to see if any information is propagated into this login List authzTokenList = ((WSTokenHolderCallback) callbacks[1]).
getTokenHolderList();
if (authzTokenList != null)
{
for (int i = 0; i< authzTokenList.size(); i++)
{
TokenHolder tokenHolder = (TokenHolder)authzTokenList.get(i);
// Look for your custom object. Make sure you use
// "startsWith"because there is some data appended
// to the end of the name indicating in which Subject
// Set it belongs. Example from getName():
// "com.acme.CustomObject (1)". The class name is
// generated at the sending side by calling the
// object.getClass().getName() method. If this object
// is deserialized by WebSphere Application Server,
// then return it and you do not need to add it here.
// Otherwise, you can add it below.
// Note: If your class appears in this list and does
// not use custom serialization (for example, an
// implementation of the Token interface described in
// the Propagation Token Framework), then WebSphere
// Application Server automatically deserializes the
// Java object for you. You might just return here if
// it is found in the list.
if (tokenHolder.getName().startsWith("com.acme.CustomObject"))
return true;
}
}
// If you get to this point, then your custom object has not propagated myCustomObject = new com.acme.CustomObject();
myCustomObject.put("mykey", "mydata");
}
public boolean commit() throws LoginException
{
try
{
// Assigns a reference to a final variable so it can be used in
// the doPrivileged block final com.acme.CustomObject myCustomObjectFinal = myCustomObject;
// Prevents your applications from needing a JAAS getPrivateCredential
// permission.
java.security.AccessController.doPrivileged(new java.security.
PrivilegedExceptionAction()
{
public Object run() throws java.lang.Exception {
// Try not to add a null object to the Subject or an object
// that already exists.
if (myCustomObjectFinal != null && !subject.getPrivateCredentials().
contains(myCustomObjectFinal))
{
// This call requires a special Java 2 Security permission,
// see the JAAS application programming interface (API)
// documentation.
subject.getPrivateCredentials().add(myCustomObjectFinal);
}
return null;
}
});
}
catch (java.security.PrivilegedActionException e)
{
// Wraps the exception in a WSLoginFailedException java.lang.Throwable myException = e.getException();
throw new WSLoginFailedException (myException.getMessage(), myException);
}
}
// Defines your login module variables com.acme.CustomObject myCustomObject = null;
}
If you are careful adding custom objects and follow all the steps to make sure that WebSphere Application Server can serialize and deserialize the object at each hop, then it is sufficient to use custom Java objects only.
When you add a custom object into the Subject and expect WebSphere Application Server to propagate the object, make sure that the class definition for that custom object exists in the install_root/classes directory on all of the nodes where serialization or deserialization might occur. Also, verify that the Java class versions are the same.
Related reference
Security: Resources for learning
Custom login module development for a system login configuration
Default authorization token
Default propagation token