In the same way the SecurityManager protects you from an untrusted applet running in your browser, use of a SecurityManager while running Tomcat can protect your server from trojan servlets, JSP's, JSP beans, and tag libraries. Or even inadvertent mistakes.
Imagine if someone who is authorized to publish JSP's on your site invadvertently included the following in their JSP:
<% System.exit(1); %>
Every time that JSP was executed by Tomcat, Tomcat would exit.
Using the Java SecurityManager is just one more line of defense a system administrator can use to keep the server secure and reliable.
Still, running with a SecurityManager is definitely better than running
without one.
This is just a short summary of the System SecurityManager Permission classes applicable to Tomcat. Please refer to http://java.sun.com/security/ for more information on using the Java SecurityManager and the below Permissions.
java.util.PropertyPermission
Controls read/write access to JVM properties such
as java.home.
java.lang.RuntimePermission
Controls use of some System/Runtime functions like
exit() and exec().
java.io.FilePermission
Controls read/write/execute access to files and
directories.
java.net.SocketPermission
Controls use of network sockets.
java.net.NetPermission
Controls use of multicast network connections.
java.lang.reflect.ReflectPermission
Controls use of reflection to do class introspection.
java.security.SecurityPermission
Controls access to Security methods.
java.security.AllPermission
Allows access to all permissions, just as if you
were running Tomcat without a SecurityManager.
Example:
permission org.apache.naming.JndiPermission "jndi://localhost/examples/*";
The security policies implemented by the Java SecurityManager are configured in the catalina.policy file located in the tomcat conf directory. The catalina.policy file replaces any system java.policy file. The catalina.policy file can be edited by hand or you can use the policytoolapplication that comes with Java 1.2.
Entries in the catalina.policy file use the standard java.policy file format as follows:
// Example policy file entry
grant [signedBy <signer> [,codeBase <code source>] {
permission <class> [<name> [, <action list>]];
};
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The codeBase is in the form of a URL and for a file URL can use the ${java.home} and ${catalina.home} properties which are expanded out to the directory paths defined for them.
Default catalina.policy file
// ============================================================================
// catalina.corepolicy - Security Policy Permissions for Tomcat 4.0
//
// This file contains a default set of security policies to be enforced (by the
// JVM) when Catalina is executed with the "-security" option. In addition
// to the permissions granted here, the following additional permissions are
// granted to the codebase specific to each web application:
//
// * Read access to the document root directory
//
// $Id$
// ============================================================================
// ========== SYSTEM CODE PERMISSIONS =========================================
// These permissions apply to javac
grant codeBase "file:${java.home}/lib/-" {
permission java.security.AllPermission;
};
// These permissions apply to all shared system extensions
grant codeBase "file:${java.home}/jre/lib/ext/-" {
permission java.security.AllPermission;
};
// These permissions apply to javac when ${java.home] points at $JAVA_HOME/jre
grant codeBase "file:${java.home}/../lib/-" {
permission java.security.AllPermission;
};
// These permissions apply to all shared system extensions when
// ${java.home} points at $JAVA_HOME/jre
grant codeBase "file:${java.home}/lib/ext/-" {
permission java.security.AllPermission;
};
// ========== CATALINA CODE PERMISSIONS =======================================
// These permissions apply to the server startup code
grant codeBase "file:${catalina.home}/bin/bootstrap.jar" {
permission java.security.AllPermission;
};
// These permissions apply to the servlet API classes
// and those that are shared across all class loaders
// located in the "common" directory
grant codeBase "file:${catalina.home}/common/-" {
permission java.security.AllPermission;
};
// These permissions apply to the container's core code, plus any additional
// libraries installed in the "server" directory
grant codeBase "file:${catalina.home}/server/-" {
permission java.security.AllPermission;
};
// These permissions apply to the jasper page compiler
// located in the "jasper" directory.
grant codeBase "file:${catalina.home}/jasper/-" {
permission java.security.AllPermission;
};
// These permissions apply to shared web application libraries
// including the Jasper runtime library installed in the "lib" directory
grant codeBase "file:${catalina.home}/lib/-" {
permission java.security.AllPermission;
};
// These permissions apply to shared web application classes
// located in the "classes" directory
grant codeBase "file:${catalina.home}/classes/-" {
permission java.security.AllPermission;
};
// ========== WEB APPLICATION PERMISSIONS =====================================
// These permissions are granted by default to all web applications
// In addition, a web application will be given a read FilePermission
// and JndiPermission for all files and directories in its document root.
grant {
// Required for JNDI lookup of named JDBC DataSource's and
// javamail named MimePart DataSource used to send mail
permission java.utim.PropertyPermission "java.home", "read";
permission java.util.PropertyPermission "java.naming.*", "read";
permission java.util.PropertyPermission "javax.sql.*", "read";
// OS Specific properties to allow read access
permission java.util.PropertyPermission "os.name", "read";
permission java.util.PropertyPermission "os.version", "read";
permission java.util.PropertyPermission "os.arch", "read";
permission java.util.PropertyPermission "file.separator", "read";
permission java.util.PropertyPermission "path.separator", "read";
permission java.util.PropertyPermission "line.separator", "read";
// JVM properties to allow read access
permission java.util.PropertyPermission "java.version", "read";
permission java.util.PropertyPermission "java.vendor", "read";
permission java.util.PropertyPermission "java.vendor.url", "read";
permission java.util.PropertyPermission "java.class.version", "read";
permission java.util.PropertyPermission "java.specification.version", "read";
permission java.util.PropertyPermission "java.specification.vendor", "read";
permission java.util.PropertyPermission "java.specification.name", "read";
permission java.util.PropertyPermission "java.vm.specification.version", "read";
permission java.util.PropertyPermission "java.vm.specification.vendor", "read";
permission java.util.PropertyPermission "java.vm.specification.name", "read";
permission java.util.PropertyPermission "java.vm.version", "read";
permission java.util.PropertyPermission "java.vm.vendor", "read";
permission java.util.PropertyPermission "java.vm.name", "read";
// Required for getting BeanInfo
permission java.lang.RuntimePermission "accessClassInPackage.sun.beans.*";
// Allow read of JAXP compliant XML parser debug
permission java.util.PropertyPermission "jaxp.debug", "read";
};
// You can assign additional permissions to particular web applications by
// adding additional "grant" entries here, based on the code base for that
// application, /WEB-INF/classes/, or /WEB-INF/lib/ jar files.
//
// Different permissions can be granted to JSP pages, classes loaded from
// the /WEB-INF/classes/ directory, all jar files in the /WEB-INF/lib/
// directory, or even to individual jar files in the /WEB-INF/lib/ directory.
//
// For instance, assume that the standard "examples" application
// included a JDBC driver that needed to establish a network connection to the
// corresponding database and used the scrape taglib to get the weather from
// the NOAA web server. You might create a "grant" entries like this:
//
// The permissions granted to the context root directory apply to JSP pages.
// grant codeBase "file:${catalina.home}/webapps/examples/-" {
// permission java.net.SocketPermission "dbhost.mycompany.com:5432", "connect";
// permission java.net.SocketPermission "*.noaa.gov:80", "connect";
// };
//
// The permissions granted to the context WEB-INF/classes directory
// grant codeBase "file:${catalina.home}/webapps/examples/WEB-INF/classes/-" {
// };
//
// The permission granted to your JDBC driver
// grant codeBase "file:${catalina.home}/webapps/examples/WEB-INF/lib/driver.jar!/-" {
// permission java.net.SocketPermission "dbhost.mycompany.com:5432", "connect";
// };
// The permission granted to the scrape taglib
// grant codeBase "file:${catalina.home}/webapps/examples/WEB-INF/lib/scrape.jar!/-" {
// permission java.net.SocketPermission "*.noaa.gov:80", "connect";
// };
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