A default propagation token is located on the running thread
for applications and the security infrastructure to use. The product
propagates this default propagation token downstream and the token
stays on the thread where the invocation lands at each hop.
About this task
The data is available from within the container of any
resource where the propagation token lands. Remember that you must
enable the propagation feature at each server where a request is sent
for propagation to work. Make sure that you enable security attribute
propagation for all of the cells in your environment where you want
propagation
There is a WSSecurityHelper class that has application
programming interfaces (APIs) for accessing the PropagationToken attributes.
This topic documents the usage scenarios and includes examples. A
close relationship exists between the propagation token and the work
area feature. The main difference between these features is that after
you add attributes to the propagation token, you cannot change the
attributes. You cannot change these attributes so that the security
runtime can add auditable information and have that information remain
there for the life of the invocation. Any time that you add an attribute
to a specific key, an ArrayList object is stored to hold that attribute.
Any new attribute that is added with the same key is added to the
ArrayList object. When you call getAttributes, the ArrayList object
is converted to a String array and the order is preserved. The first
element in the String array is the first attribute added for that
specific key.
In the default propagation token, a change flag
is kept that logs any data changes to the token. These changes are
tracked to enable WebSphere® Application Server to
know when to send the authentication information downstream again
so that the downstream server has those changes. Normally, Common
Secure Interoperability Version 2 (CSIv2) maintains a session between
servers for an authenticated client. If the propagation token changes,
a new session is generated and subsequently a new authentication occurs.
Frequent changes to the propagation token during a method cause frequent
downstream calls. If you change the token prior to making many downstream
calls or you change the token between each downstream call, you might
impact security performance.
- Obtain the server list from the default propagation token.
Every time the propagation token is propagated and used to
create the authenticated Subject, either horizontally or downstream,
the name of the receiving application server is logged into the propagation
token. The format of the host is "Cell:Node:Server",
which provides you access to the cell name, node name, and server
name of each application server that receives the invocation.
The following code provides you with this list of names
and can be called from a Java 2
Platform, Enterprise Edition (J2EE) application.
The format
of each server in the list is: cell:node_name:server_name.
The output, for example, is: myManager:node1:server1
String[] server_list = null;
// If security is disabled on this application server, do not bother checking
if (com.ibm.websphere.security.WSSecurityHelper.isServerSecurityEnabled())
{
try
{
// Gets the server_list string array
server_list = com.ibm.websphere.security.WSSecurityHelper.getServerList();
}
catch (Exception e)
{
// Performs normal exception handling for your application
}
if (server_list != null)
{
// print out each server in the list, server_list[0] is the first server
for (int i=0; i<server_list.length; i++)
{
System.out.println("Server[" + i + "] = " + server_list[i]);
}
}
}
- Obtain the list of callers, using the getCallerList API.
A default propagation token is generated any time an authenticated
user is set on the running thread or anyone tries to add attributes
to the propagation token. Whenever an authenticated user is set on
the thread, the user is logged in the default propagation token. At
times, the same user might be logged in multiple times if the RunAs
user is different from the caller. The following list provides the
rules that are used to determine if a user that is added to the thread
gets logged into the propagation token:
- The current Subject must be authenticated. For example, an unauthenticated
Subject is not logged.
- The current authenticated Subject is logged if a Subject is not
previously logged.
- The current authenticated Subject is logged if the last authenticated
Subject that is logged does not contain the same user.
- The current authenticated Subject is logged on each unique application
server that is involved in the propagation process.
The following code sample shows how to
use the getCallerList API.
The format of each caller in the
list is: cell:node_name:server_name:realm:port_number/securityName.
The output, for example, is: myManager:node1:server1:ldap.austin.ibm.com:389/jsmith.
String[] caller_list = null;
// If security is disabled on this application server, do not check the caller list
if (com.ibm.websphere.security.WSSecurityHelper.isServerSecurityEnabled())
{
try
{
// Gets the caller_list string array
caller_list = com.ibm.websphere.security.WSSecurityHelper.getCallerList();
}
catch (Exception e)
{
// Performs normal exception handling for your application
}
if (caller_list != null)
{
// Prints out each caller in the list, caller_list[0] is the first caller
for (int i=0; i<caller_list.length;i++)
{
System.out.println("Caller[" + i + "] = " + caller_list[i]);
}
}
}
- Obtain the security name of the first authenticated user,
using the getFirst Caller API.
Whenever you want to
know which authenticated caller started the request, you can call
the getFirstCaller method and the caller list is parsed. However,
this method returns the security name of the caller only. If you need
to know more than the security name, call the getCallerList method
and retrieve the first entry in the String array. This entry provides
all the caller information.
The following code
sample retrieves the security name of the first authenticated caller
using the getFirstCaller API.
The output, for example, is:
jsmith.
String first_caller = null;
// If security is disabled on this application server, do not bother checking
if (com.ibm.websphere.security.WSSecurityHelper.isServerSecurityEnabled())
{
try
{
// Gets the first caller
first_caller = com.ibm.websphere.security.WSSecurityHelper.getFirstCaller();
// Prints out the caller name
System.out.println("First caller: " + first_caller);
}
catch (Exception e)
{
// Performs normal exception handling for your application
}
}
- Obtain the name of the first application server for a request,
using the getFirstServer method.
Whenever you want to
know what the first application server is for this request, call the
getFirstServer method directly.
The following
code sample retrieves the name of the first application server using
the getFirstServer API.
The output, for example, is: myManager:node1:server1.
String first_server = null;
// If security is disabled on this application server, do not bother checking
if (com.ibm.websphere.security.WSSecurityHelper.isServerSecurityEnabled())
{
try
{
// Gets the first server
first_server = com.ibm.websphere.security.WSSecurityHelper.getFirstServer();
// Prints out the server name
System.out.println("First server: " + first_server);
}
catch (Exception e)
{
// Performs normal exception handling for your application
}
}
- Add custom attributes to the default propagation token,
using the addPropagationAttribute API.
You can add custom
attributes to the default propagation token for application usage.
This token follows the request downstream so that the attributes are
available when needed. When you use the default propagation token
to add attributes, you must understand the following issues:
- Adding information to the propagation token affects CSIv2 session
caching. Add information sparingly between remote requests.
- After you add information with a specific key, the information
cannot be removed.
- You can add as many values to a specific key as you need. However,
all of the values must be available from a returned String array in
the order that they were added.
- The propagation token is available only on servers where propagation
and security are enabled.
- The Java 2 Security javax.security.auth.AuthPermission
wssecurity.addPropagationAttribute attribute is needed to add attributes
to the default propagation token.
- An application cannot use keys that begin with either com.ibm.websphere.security
or com.ibm.wsspi.security. These prefixes are reserved for system
usage.
The following code sample shows how to
use the addPropagationAttribute API.
// If security is disabled on this application server,
// do not check the status of server security
if (com.ibm.websphere.security.WSSecurityHelper.isServerSecurityEnabled())
{
try
{
// Specifies the key and values
String key = "mykey";
String value1 = "value1";
String value2 = "value2";
// Sets key, value1
com.ibm.websphere.security.WSSecurityHelper.
addPropagationAttribute (key, value1);
// Sets key, value2
String[] previous_values = com.ibm.websphere.security.WSSecurityHelper.
addPropagationAttribute (key, value2);
// Note: previous_values should contain value1
}
catch (Exception e)
{
// Performs normal exception handling for your application
}
}
- Obtain your custom attributes with the get PropagationAttributes
API.
Custom attributes are added to the default propagation
token using the addPropagationAttribute API. Retrieve these attributes
using the getPropagationAttributes API. This token follows the request
downstream so the attributes are available when needed. When you use
the default propagation token to retrieve attributes, you must understand
the following issues:
- The propagation token is available only on servers where propagation
and security are enabled.
- The Java 2 Security javax.security.auth.AuthPermission
"wssecurity.getPropagationAttributes" permission is needed to retrieve
attributes from the default propagation token.
See Adding
custom attributes to the default PropagationToken to add attributes
using the addPropagationAttributes API.
The
following code sample shows how to use the getPropagationAttributes
API.
// If security is disabled on this application server, do not bother checking
if (com.ibm.websphere.security.WSSecurityHelper.isServerSecurityEnabled())
{
try
{
String key = "mykey";
String[] values = null;
// Sets key, value1
values = com.ibm.websphere.security.WSSecurityHelper.
getPropagationAttributes (key);
// Prints the values
for (int i=0; i<values.length; i++)
{
System.out.println("Value[" + i + "] = " + values[i]);
}
}
catch (Exception e)
{
// Performs normal exception handling for your application
}
}
The output, for example, is:
Value[0] = value1
Value[1] = value2
- Modify the propagation token factory configuration to use
a token factory other than the default token factory.
When WebSphere Application Server generates a default
propagation token, the Application Server utilizes the TokenFactory
class that is specified using the com.ibm.wsspi.security.token.propagationTokenFactory
property.
The default token factory that is specified for this
property is called com.ibm.ws.security.ltpa.AuthzPropTokenFactory.
This token factory encodes the data in the propagation token and does
not encrypt the data. Because the propagation token typically flows
over CSIv2 using Secure Sockets Layer (SSL), encrypting the token
is not required. However, if you need additional security for the
propagation token, you can associate a different token factory implementation
with this property to get encryption. For example, if you choose to
associate the com.ibm.ws.security.ltpa.LTPAToken2Factory token factory
with this property, the token is AES encrypted. However, you need
to weigh the performance impacts against your security needs. Adding
sensitive information to the propagation token is a good reason to
change the token factory implementation to something that encrypts
rather than just encodes.
- Open the administrative console.
- Click Security > Global security.
- Click Custom properties.
- Perform your own signing and encryption of the default
propagation token.
If you want to perform your own signing
and encryption of the default propagation token, you must implement
the following classes:
- com.ibm.wsspi.security.ltpa.Token
- com.ibm.wsspi.security.ltpa.TokenFactory
Your token factory implementation instantiates and validates
your token implementation. You can choose to use the Lightweight Third
Party Authentication (LTPA) keys and have them pass into the initialize
method of the token factory, or you can use your own keys. If you
use your own keys, they must be the same everywhere to validate the
tokens that are generated using those keys. See the API documentation,
available through a link on the front page of the information center,
for more information on implementing your own custom token factory.
- Associate your token factory with the default propagation
token.
- Open the administrative console.
- Click Security > Global security.
- Click Custom properties.
- Locate the com.ibm.wsspi.security.token.propagationTokenFactory
property and verify that the value of this property matches your custom
token factory implementation.
- Verify that your implementation classes are put into
the app_server_root/classes directory
so that the WebSphere Application Server class
loader can load the classes.
![[AIX Solaris HP-UX Linux Windows]](../images/dist.gif)
Verify that your implementation
classes are located in the ${USER_INSTALL_ROOT}/classes directory
so that the WebSphere Application Server class
loader can load the classes.
Verify that the QEJBSVR user profile
has read, write, and execute (*RWX) authority to the classes directory.
You can use the Work with Authority (WRKAUT) command to view the authority
permissions for the directory.