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<!DOCTYPE document [
  <!ENTITY project SYSTEM "project.xml">
  <!ENTITY defaultpolicy SYSTEM "../../conf/catalina.policy">
]>
<document url="security-manager-howto.html">

    &project;

    <properties>
        <title>Security Manager How-To</title>
    </properties>

<body>

<section name="Table of Contents">
<toc/>
</section>

<section name="Background">

  <p>The Java <strong>SecurityManager</strong> is what allows a web browser
  to run an applet in its own sandbox to prevent untrusted code from
  accessing files on the local file system, connecting to a host other
  than the one the applet was loaded from, and so on.  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, JSPs, JSP beans, and tag libraries.
  Or even inadvertent mistakes.</p>

  <p>Imagine if someone who is authorized to publish JSPs on your site
  inadvertently included the following in their JSP:</p>
<source><![CDATA[<% System.exit(1); %>]]></source>

  <p>Every time this 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.</p>

  <p><strong>WARNING</strong> - A security audit
  have been conducted using the Tomcat codebase. Most of the critical
  package have been protected and a new security package protection mechanism
  has been implemented. Still, make sure that you are satisfied with your SecurityManager
  configuration before allowing untrusted users to publish web applications,
  JSPs, servlets, beans, or tag libraries.  <strong>However, running with a
  SecurityManager is definitely better than running without one.</strong></p>

</section>


<section name="Known Issues">

  <p>As of Java 17, the SecurityManager has been deprecated with the expectation
  that it will be removed in a future Java version. Users currently using a
  SecurityManager are recommended to start planning for its removal.</p>

</section>


<section name="Permissions">

  <p>Permission classes are used to define what Permissions a class loaded
  by Tomcat will have.  There are a number of Permission classes that are
  a standard part of the JDK, and you can create your own Permission class
  for use in your own web applications.  Both techniques are used in
  Tomcat.</p>


  <subsection name="Standard Permissions">

    <p>This is just a short summary of the standard system SecurityManager
    Permission classes applicable to Tomcat.  See
    <a href="http://docs.oracle.com/javase/7/docs/technotes/guides/security/">
    http://docs.oracle.com/javase/7/docs/technotes/guides/security/</a>
    for more information.</p>

    <ul>
    <li><strong>java.util.PropertyPermission</strong> - Controls read/write
        access to JVM properties such as <code>java.home</code>.</li>
    <li><strong>java.lang.RuntimePermission</strong> - Controls use of
        some System/Runtime functions like <code>exit()</code> and
        <code>exec()</code>. Also control the package access/definition.</li>
    <li><strong>java.io.FilePermission</strong> - Controls read/write/execute
        access to files and directories.</li>
    <li><strong>java.net.SocketPermission</strong> - Controls use of
        network sockets.</li>
    <li><strong>java.net.NetPermission</strong> - Controls use of
        multicast network connections.</li>
    <li><strong>java.lang.reflect.ReflectPermission</strong> - Controls
        use of reflection to do class introspection.</li>
    <li><strong>java.security.SecurityPermission</strong> - Controls access
        to Security methods.</li>
    <li><strong>java.security.AllPermission</strong> - Allows access to all
        permissions, just as if you were running Tomcat without a
        SecurityManager.</li>
    </ul>

  </subsection>

</section>


<section name="Configuring Tomcat With A SecurityManager">

  <h3>Policy File Format</h3>

  <p>The security policies implemented by the Java SecurityManager are
  configured in the <code>$CATALINA_BASE/conf/catalina.policy</code> file.
  This file completely replaces the <code>java.policy</code> file present
  in your JDK system directories.</p>

  <p>Entries in the <code>catalina.policy</code> file use the standard
  <code>java.policy</code> file format, as follows:</p>
<source><![CDATA[// Example policy file entry

grant [signedBy <signer>,] [codeBase <code source>] {
  permission  <class>  [<name> [, <action list>]];
};]]></source>

  <p>The <strong>signedBy</strong> and <strong>codeBase</strong> entries are
  optional when granting permissions.  Comment lines begin with "//" and
  end at the end of the current line.  The <code>codeBase</code> is in the
  form of a URL, and for a file URL can use the <code>${java.home}</code>
  and <code>${catalina.home}</code> properties (which are expanded out to
  the directory paths defined for them by the <code>JAVA_HOME</code>,
  <code>CATALINA_HOME</code> and <code>CATALINA_BASE</code> environment
  variables).</p>

  <h3>The Default Policy File</h3>

  <p>The default <code>$CATALINA_BASE/conf/catalina.policy</code> file
  looks like this:</p>

<!-- The following pulls in the conf/catalina.policy file when the
 documentation is built -->
<source>&defaultpolicy;</source>

  <h3>Starting Tomcat With A SecurityManager</h3>

  <p>Once you have configured the <code>catalina.policy</code> file for use
  with a SecurityManager, Tomcat can be started with a SecurityManager in
  place by using the "-security" option:</p>
<source>$CATALINA_HOME/bin/catalina.sh start -security    (Unix)
%CATALINA_HOME%\bin\catalina start -security      (Windows)</source>

  <subsection name="Permissions for packed WAR files">

    <p>When using packed WAR files, it is necessary to use Tomcat's custom war
    URL protocol to assign permissions to web application code.</p>

    <p>To assign permissions to the entire web application the entry in the
    policy file would look like this:</p>

<source><![CDATA[// Example policy file entry
grant codeBase "war:file:${catalina.base}/webapps/examples.war*/-" {
    ...
};
]]></source>

    <p>To assign permissions to a single JAR within the web application the
    entry in the policy file would look like this:</p>

<source><![CDATA[// Example policy file entry
grant codeBase "war:file:${catalina.base}/webapps/examples.war*/WEB-INF/lib/foo.jar" {
    ...
};
]]></source>

  </subsection>

</section>

<section name="Configuring Package Protection in Tomcat">
  <p>Starting with Tomcat 5, it is now possible to configure which Tomcat
  internal package are protected against package definition and access. See
  <a href="http://www.oracle.com/technetwork/java/seccodeguide-139067.html">
    http://www.oracle.com/technetwork/java/seccodeguide-139067.html</a>
    for more information.</p>


  <p><strong>WARNING</strong>: Be aware that removing the default package protection
  could possibly open a security hole</p>

  <h3>The Default Properties File</h3>

  <p>The default <code>$CATALINA_BASE/conf/catalina.properties</code> file
  looks like this:</p>
<source><![CDATA[#
# List of comma-separated packages that start with or equal this string
# will cause a security exception to be thrown when
# passed to checkPackageAccess unless the
# corresponding RuntimePermission ("accessClassInPackage."+package) has
# been granted.
package.access=sun.,org.apache.catalina.,org.apache.coyote.,org.apache.tomcat.,
org.apache.jasper.
#
# List of comma-separated packages that start with or equal this string
# will cause a security exception to be thrown when
# passed to checkPackageDefinition unless the
# corresponding RuntimePermission ("defineClassInPackage."+package) has
# been granted.
#
# by default, no packages are restricted for definition, and none of
# the class loaders supplied with the JDK call checkPackageDefinition.
#
package.definition=sun.,java.,org.apache.catalina.,org.apache.coyote.,
org.apache.tomcat.,org.apache.jasper.]]></source>
  <p>Once you have configured the <code>catalina.properties</code> file for use
  with a SecurityManager, remember to re-start Tomcat.</p>
</section>

<section name="Troubleshooting">

  <p>If your web application attempts to execute an operation that is
  prohibited by lack of a required Permission, it will throw an
  <code>AccessControLException</code> or a <code>SecurityException</code>
  when the SecurityManager detects the violation.  Debugging the permission
  that is missing can be challenging, and one option is to turn on debug
  output of all security decisions that are made during execution.  This
  is done by setting a system property before starting Tomcat.  The easiest
  way to do this is via the <code>CATALINA_OPTS</code> environment variable.
  Execute this command:</p>
<source>export CATALINA_OPTS=-Djava.security.debug=all    (Unix)
set CATALINA_OPTS=-Djava.security.debug=all       (Windows)</source>

  <p>before starting Tomcat.</p>

  <p><strong>WARNING</strong> - This will generate <em>many megabytes</em>
  of output!  However, it can help you track down problems by searching
  for the word "FAILED" and determining which permission was being checked
  for.  See the Java security documentation for more options that you can
  specify here as well.</p>

</section>


</body>

</document>
