Java 2 security

Java 2 security provides a policy-based, fine-grain access control mechanism that increases overall system integrity by checking for permissions before allowing access to certain protected system resources. Java 2 security guards access to system resources such as file I/O, sockets, and properties. J2EE security guards access to Web resources such as servlets, JSP files and EJB methods. WebSphere global security includes J2EE role-based authorization, the CSIv2 authentication protocol, and SSL configuration.

Since Java 2 security is relatively new, many existing or even new applications might not be prepared for the very fine-grain access control programming model that Java 2 security is capable of enforcing. Administrators should understand the possible consequences of enabling Java 2 security if applications are not prepared for Java 2 security. Java 2 security places some new requirements on application developers and administrators.

Java 2 security for deployers and administrators

Although Java 2 security is supported in WAS V5, it is disabled by default. However, it is enabled automatically if you also enable global security when configuring security. Although it becomes enabled automatically when you enable WebSphere global security, one can choose to disable it. One can configure Java 2 security and global security independently of one another. Disabling global security does not disable Java 2 security automatically. You need to explicitly disable it.

If your applications, or third-party libraries are not ready, having Java 2 security enabled causes problems. We can identify these problems as Java 2 security AccessControlExceptions in the SystemOut.log file, SystemError.log file, or the trace log files. If you are unsure about the Java 2 security readiness of your applications, disable Java 2 security initially to get your application installed and verify that it is working properly.

There are implications if Java 2 Security is enabled; deployers or administrators are required to make sure that all the applications are granted the required permissions, otherwise, applications might fail to run. By default, applications are granted the permissions recommended in the J2EE 1.3 Specification. For details of default permissions granted to applications in the product, refer to the following policy files:

Note: This policy embodied by these policy files cannot be made more restrictive because the product might not have the necessary Java 2 security doPrivileged APIs in place. The restrictive policy is the default policy. We can grant additional permissions, but one cannot make the default more restrictive because AccessControlExceptions is generated from within WAS. The product does not support a more restrictive policy than the default defined in the policy files previously mentioned.

There are several policy files used to define the security policy for the Java process. These policy files are static (code base is defined in the policy file) and they are in the default policy format provided by the IBM Developer Kit, Java Technology Edition. For enterprise application resources and utility libraries, WAS provides dynamic policy support. The code base is dynamically calculated based on deployment information and permissions are granted based on template policy files during run time. Refer to the article, Java 2 security policy files for more information.

Note: Syntax errors in the policy files cause the application server process to fail. Edit these policy files carefully using the Policy Tool provided by the IBM Developer Kit, Java Technology Edition for editing the policy files (install_root/java/jre/bin/policytool).

If an application is not prepared for Java 2 security, if the application provider does not provide a was.policy file as part of the application, or if the application provider does not communicate the expected permissions the application is likely to cause Java 2 security access control exceptions at run time. It might not be obvious that an application is not prepared for Java 2 security. Several run-time debugging aids help troubleshoot applications that might have access control exceptions. See the Java 2 security debugging aids for more details. See Handling applications that are not Java 2 security ready for information and strategies for dealing with such applications.

It is important to note that when Java 2 Security is enabled in the Global Security settings, the installed SecurityManager does not currently check modifyThread and modifyThreadGroup permissions for non-system threads. Allowing Web and EJB application code to create or modify a thread can have a negative impact on other components of the container and can affect the capability of the container to manage enterprise bean life cycles and transactions.

Java 2 security for application developers

Application developers must understand the permissions granted in the default WebSphere policy and the permission requirements of the SDK APIs that their application calls to know whether additional permissions are required. The "Permissions in the Java 2 SDK" reference in the resources section describes which APIs require which permission.

Application providers can assume that applications have the permissions granted in the default policy previously mentioned. Applications that access resources not covered by the default WebSphere policy are required to grant the additional Java 2 security permissions to the application.

While it is possible to grant the application additional permissions in one of the other dynamic WebSphere policy files or in one of the more traditional static policy files, such as java.policy, the was.policy (which is embedded in the EAR file) ensures the additional permissions are scoped to the exact application that requires them. Scoping the permission beyond the application code that requires it can permit code that normally does not have permission to access particular resources.

If an application component is being developed, like a library that might actually be included in more than one .ear file, then the library developer should document the required Java 2 permissions needed by the application assembler. There is no was.policy file for library type components. The developer must communicate the required permissions through API documentation or some other external documentation.

If the component library is shared by multiple enterprise applications, the permissions can be granted to all enterprise applications on the node in the app.policy file.

If the permission is only used internally by the component library and the application should never be granted access to resources protected by the permission, then it might be necessary to mark the code as privileged (inserting doPrivileged). Refer to the article, AccessControlException, for more details. However, improperly inserting a doPrivileged might open up security holes. Understand the implication of doPrivileged to make a correct judgement whether a doPrivileged should be inserted or not.

The section on Dynamic Policy describes how the permissions in the was.policy files are granted at run time.

Developing an application with Java 2 security in mind might be a new skill and impose a security awareness not previously required of application developers. Describing the Java 2 security model and the implications on application development is beyond the scope of this section. The following URL can help you get started: http://java.sun.com/j2se/1.3/docs/guide/security/index.html.

Debugging Aids

The WebSphere SystemOut.log File

The AccessControl exception logged in the SystemOut.log file contains the permission violation that causes the exception, the exception call stack, and the permissions granted to each stack frame. This information is usually enough to determine the missing permission and the code requiring the permission.

The com.ibm.websphere.java2secman.norethrow Property

When Java 2 security is enabled in WAS, the security manager component throws a java.security.AccessControl exception when a permission violation occurs. This exception, if not handled, often causes a run-time failure. This exception is also logged in the SystemOut.log file.

However, when the JVM com.ibm.websphere.java2secman.norethrow property is set and has a value of true, the security manager does not throw the AccessControl exception. This information is logged.

To set the com.ibm.websphere.java2secman.norethrow property for the server, go to...

To set the com.ibm.websphere.java2secman.norethrow property for the node agent, go to..

Note: This property is intended for a sandbox or debug environment because it instructs the security manager not to throw the AccessControl exception. Java 2 security is not enforced. This property should not be used in a production environment where a relaxed Java 2 security environment weakens the integrity that Java 2 security is intended to produce.

This property is valuable in a sandbox or test environment where the application can be thoroughly tested and the where the SystemOut.log file can be inspected for AccessControl exceptions. Since this property does not throw the AccessControl exception , it does not propagate the call stack and does not cause a failure. Without this property, you have to find and fix AccessControl exceptions one at a time.

Handling applications that are not Java 2 security ready

If the increased system integrity that Java 2 security provides is important, then contact the application provider to have the application support Java 2 security or at least communicate the required additional permissions beyond the default WebSphere policy that must be granted.

The easiest way to deal with such applications is to disable Java 2 security in WAS. The downside is that this solution applies to the entire system and the integrity of the system is not as strong as it might be. Disabling Java 2 security might not be acceptable depending on the organization security policies or risk tolerances.

Another approach is to leave Java 2 security enabled, but to grant either just enough additional permissions or grant all permissions to just the problematic application. Granting permissions however, might not be a trivial thing to do. If the application provider has not communicated the required permissions in some way, there is no easy way to determine what the required permissions are and granting all permissions might be the only choice. You minimize this risk by locating this application on a different node, which might help isolate it from certain resources. Grant the java.security.AllPermission permission in the was.policy file embedded in the application's .ear file, for example:

grant codeBase "file:${application}" 
{
    permission java.security.AllPermission;
};

install_root/properties/server.policy

This policy defines the policy for the WebSphere classes. At present, all the server processes on the same installation share the same server.policy file. However, one can configure this file so that each server process can have a separate server.policy file. Define the desired policy file as the value of the Java system properties java.security.policy. For details of how to define Java system properties, Refer to the Process definition section of the Manage application servers file.

The server.policy file is not a configuration file managed by the repository and the file replication service. Changes to this file are local and do not get replicated to other machines. Use the server.policy file to define Java 2 security policy for server resources. Use the app.policy file (per node) or was.policy file (per enterprise application) to define Java 2 security policy for enterprise application resources.

WAS_HOME/java/jre/lib/security/java.policy

The file represents the default permissions granted to all classes. The policy of this file applies to all the processes launched by the WAS JVM.

Troubleshoot

Symptom:

Error message CWSCJ0314E: Current Java 2 security policy reported a potential violation of Java 2 security permission. Refer to Problem Determination Guide for further information.
{0}Permission\:{1}Code\:{2}{3}Stack Trace\:{4}Code Base Location\:{5}
Current Java 2 security policy reported a potential violation of Java 2 Security Permission.

Problem:

The Java security manager checkPermission() reported a SecurityException on the subject permission with debugging information. The reported information can be different with respect to the system configuration. This report is enabled by either configuring RAS trace into debug mode or specifying a Java property.

Specify the following property in the JVM Settings panel from the administrative console:

java.security.debug

Valid values include:

access

Print all debug information including: required permission, code, stack, and code base location.

stack

Print debug information including: required permission, code, and stack.

failure

Print debug information including: required permission and code.

Recommended response:

The reported exception might be critical to the secure system. Turn on security trace to determine the potential code that might have violated the security policy. Once the violating code is determined, verify if the attempted operation is permitted with respect to Java 2 security, by examining all applicable Java 2 security policy files and the application code.

Note: If the application is running with Java Mail, this message might be benign. User can update the was.policy file to grant the following permissions to the application.

permission java.io.FilePermission "${user.home}${/}.mailcap", "read";
permission java.io.FilePermission "${user.home}${/}.mime.types", "read";
permission java.io.FilePermission "${java.home}${/}lib${/}mailcap", "read";
permission java.io.FilePermission "${java.home}${/}lib${/}mime.types", "read";

Messages

Message: CWSCJ0313E: Java 2 security manager debug message flags are initialized\: TrDebug: {0}, Access: {1}, Stack: {2}, Failure: {3}
Problem: Configured values of the valid debug message flags for security manager.
Recommended response: None.

Message: CWSCJ0307E: Unexpected exception is caught when trying to determine the code base location. Exception: {0}
Problem: An unexpected exception is caught when the code base location is determined.
Recommended response: Contact an IBM representative.