# ------------------------------------------------------------------
#
#    Copyright (C) 2002-2006 Novell/SUSE
#
#    This program is free software; you can redistribute it and/or
#    modify it under the terms of version 2 of the GNU General Public
#    License published by the Free Software Foundation.
#
# ------------------------------------------------------------------


----------------------

1. Overview
2. Requirements
3. Compiling the code
4. Installation
5. Generating a basic Tomcat profile
6. Implementation Notes
7. Profile Generation Tools and change_hat
8. Feedback/Resources

-----------------------


1. Overview
   --------

This package provides an implementation of a Tomcat 5.0 Valve that calls out 
to the change_hat(2) function provided by libapparmor to allow a process to 
change its security context. Any feedback is greatly appreciated.


2. Requirements
   ------------

 AppArmor version 1.2 or later
 Tomcat version 5.0.X
 JDK 1.4.2 or later


3. Compiling the Code
   -----------------

From the top level directory execute: 
  ant jar jni_so


This will create a jar file and a shared library (for the JNI interface to the 
libapparmor library) and place the jar file under dist/ and the shared library 
under src/jni_src.


4. Installation
   ------------

- Copy the jar file to $TOMCAT_HOME/server/lib:

  [SLES10 example]

  cp dist/changeHatValve.jar /usr/share/tomcat5/server/lib


- Copy the shared library to somehere in your library search path:

  cp dist/libJNIChangeHat.so /usr/lib

  [Note: you must ensure that the target directory is passed to tomcat via the
   java.library.path property. This can be accomplished by setting the JAVA_OPTS
   environment variable, export JAVA_OPTS=-Djava.library.path, or set via the
   env variable LD_LIBRARY_PATH to include this directory so that tomcat can 
   find this library at startup]


- Configure the Tomcat server to use ChangeHatValve:

  Place the configuration directive below in your server.xml file. The valve 
  definition should be the initial configuration option declared in the 
  top-level container in the container hierarchy.

  <Valve className="com.novell.apparmor.catalina.valves.ChangeHatValve"
             mediationType="ServletPath"/>

  [Note: The mediationType attribute may be set to ServletPath or URI depending 
         on the granularity of containers that you wish to create. URI will 
         prompt the user to create containers for every URI it processes. This 
         is not recommended for most deployment scenarios and so the default 
         "ServletPath" should be used. This maps to containers identified by 
         the ServletPath header defined in the HttpRequest.]


- Defining a default and required hat for the tomcat profile

  Edit the file /etc/apparmor/logprof.conf and add the following line to the 
  section [required_hats]:
     ^.+/catalina.sh$          = DEFAULT

  Edit the file /etc/apparmor/logprof.conf and add the following line to the 
  section [default_hat]:
     ^.+/catalina.sh$          = DEFAULT



 
5. Generating a basic Tomcat profile
   -------------------------------

Once the installation steps above have been started you are ready to begin 
creating a profile for your application. The profile creation tool genprof will
guide you through generating a profile and its support for change_hat will 
prompt you create discrete hats as requested by the changeHatValve during
tomcat execution.

  1. Create a basic profile for the tomcat server.

     - Run the command "genprof PATH_TO_CATALINA.SH"
     - In a separate window start tomcat and then stop tomcat
     - In the genprof window press "S" to scan for events
     - Answer the questions about the initial profile for tomcat


  2. Extending the profile to include containers for your web-app

     - Stop the tomcat server
     - Deploy your WAR file or equivalent files under the container. 
     - execute "genprof PATH_TO_CATALINA.SH"
     - In a separate window start tomcat and then exercise your web application
     - In the genprof window press "S" to scan for events
       During the prompting you will be asked questions similar to:
  
        -----------------------------------------------
    
       Profile:       /usr/share/tomcat5/bin/catalina.sh
       Default Hat:   DEFAULT
       Requested Hat: /servlet/CookieExample

  (A)dd Requested Hat / (U)se Default Hat / (D)eny / Abo(r)t / (F)inish

       ------------------------------------------------

   This example shows the tomcat valve for changehat attempting to change to 
   the hat "/servlet/CookieExample". You can choose to create this hat, and 
   subsequently fill it with resources, use the Default hat, named "DEFAULT" 
   and is the default hat for request processing. 



6. Implementation Notes
   --------------------

- Selecting the hat during request processing

This implementation follows the following pattern to decide what hat to execute in for an incoming request:

  Try #1: Request data (URI or ServletInfo) 
      if  #1 fails (because the hat does not exist) then try #2
  Try #2: DEFAULT - this is the default hat for request processing
      if #2 fails (because of any error) then..
  Error: report that change_hat calls failed and remain in current security context. 

- Java 1.4.2 Notes

  This library uses java.security.SecureRandom to generate random numbers used as cookies in 
  the change_hat(2) interface. This class on java version 1.4.2 uses /dev/random which is a 
  blocking call and can adversely effect performance. Java can be configured to use 
  /dev/urandom instead. For details:

   http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4705093 



7. Profile Tools and change_hat
   ----------------------------

When using the profile generation tool, genprof, you will be prompted to add a 
new hat when you exercise your program and requests are processed by the 
changeHatValve. You can choose to Add the hat or use the Default hat.
If you choose to add the requested hat: genprof  will create the hat and then 
all subsequent resource requests will be mediated in this hew hat (or security 
context).        
If you choose to use the default hat: genprof will mediate all resource 
requests in the default hat for the duration of processing this request.
When the request processing is complete the valve will change_hat back to the
parent context.



8. Feedback/Resources
   -----------------

Project webpage:
https://apparmor.net/

To provide feedback or ask questions please contact the
apparmor@lists.ubuntu.com mail list. This is the development list
for the AppArmor team.
