Configure filter.policy files

Java 2 security uses several policy files to determine the granted permission for each Java program. Java 2 security policy filtering is only in effect when Java 2 security is enabled. Refer to Configuring Java 2 security. The filtering policy defined in the filter.policy file is cell wide. Refer to the article, Dynamic policy, for the list of available policy files supported by WebSphere Application Server. The filter.policy file is the only policy file used when restricting the permission instead of granting permission. The permissions listed in the filter policy file are filtered out from the app.policy file and the was.policy file. Permissions defined in the other policy files are not affected by the filter.policy file.

When a permission is filtered out, an audit message is logged. However, if the permissions defined in the app.policy file and the was.policy file are compound permissions like java.security.AllPermission, for example, the permission is not removed. A warning message is logged. If the Issue Permission Warning flag is enabled (default) and if the app.policy file and the was.policy file contain custom permissions (non-Java API permission, the permission package name begins with characters other than java or javax), then a warning message is logged and the permission is not removed. You can change the value of the Issue Permission Warning flag from the administrative console in the Global Security panel. It is not recommended that you use AllPermission for the enterprise application.

There are some default permissions defined in the filter.policy file. These permissions are the minimal ones recommended by the product. If more permissions are added to the filter.policy file, certain operations can fail for enterprise applications. Add permissions to the filter.policy file carefully.

Note that

1. You cannot use the Policy Tool to edit the filter.policy file. Editing must be completed in a text editor. Be careful and verify that there are no syntax errors in the filter.policy file. If there are any syntax errors in filter.policy file, it will not be loaded by the product security run time, which implies that filtering is disabled.

An updated filter.policy file is applied to all of the WebSphere Application Server enterprise application after the servers are cycled.

 Usage scenariofilter.policy

The filter.policy file supplied by WAS resides at: $WAS_HOME/config/cells/cell/filter.policy.

It contains these permissions as defaults:

filterMask {
permission java.lang.RuntimePermission "exitVM";
permission java.lang.RuntimePermission "setSecurityManager";
permission java.security.SecurityPermission "setPolicy";
permission javax.security.auth.AuthPermission "setLoginConfiguration"; }; 
runtimeFilterMask {
permission java.lang.RuntimePermission "exitVM";
permission java.lang.RuntimePermission "setSecurityManager";
permission java.security.SecurityPermission "setPolicy";
permission javax.security.auth.AuthPermission "setLoginConfiguration"; }; 

The permissions defined in filterMask are for static policy filtering. The security run time tries to remove the permissions from applications during application startup. Compound permissions are not removed but are issued with a warning, and application deployment is stopped if applications contain permissions defined in filterMask, and if scripting was used wsadmin(tool). The runtimeFilterMask defines permissions used by the security run time to deny access to those permissions to application thread. Do not add more permissions to the runtimeFilterMask. Application start failure or incorrect functioning might result. Be careful when adding more permissions to the runtimeFilterMask. Usually, you only need to add permissions to the filterMask stanza.

WebSphere Application Server relies on the filter policy file to restrict or disallow certain permissions that could compromise the integrity of the system. For instance, WAS considers the exitVM and setSecurityManager permissions as those permissions that most applications should never have. If these permissions are granted, then the following scenarios are possible...

• exitVM -- A servlet, JSP file, enterprise bean, or other library used by the aforementioned could call the System.exit() API and cause the entire WAS process to terminate.

• setSecurityManager -- An application could install its own SecurityManager that could either grant more permissions or bypass the default policy the WAS SecurityManager enforces.

For the updated filter.policy file to take effect, restart related Java processes.

 

See Also

Java 2 security policy files
Configuring app.policy files
Configuring the was.policy file
Using PolicyTool to edit policy files

 

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