Novell APPARMOR 2.0.1 Instruction Manual

Novell AppArmor
www.novell.com2.0.1
November29,2006 Novell AppArmor Administration Guide

Novell AppArmor Administration Guide
Copyright © 2006 Novell, Inc.
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU
Free Documentation License, Version 1.2 or any later version published by the Free Software Foun-
dation; with the Invariant Section being this copyright notice and license. A copy of the license is in-
cluded in the section entitled “GNU Free Documentation License”.
Novell, the Novell logo, the N logo, openSUSE, SUSE, and the SUSE “geeko” logo are registered
trademarks of Novell, Inc. in the United States and other countries. * Linux is a registered trademark
of Linus Torvalds. All other third party trademarks are the property of their respective owners.
All information found in this book has been compiled with utmost attention to detail. However, this
does not guarantee complete accuracy. Neither Novell, Inc., SUSE LINUX Products GmbH, the authors,
nor the translators shall be held liable for possible errors or the consequences thereof.

Contents
About This Guide v
1Immunizing Programs 9
1.1 Introducing the AppArmor Framework . . . . . . . . . . . . . . . . 10
1.2 Determining Programs to Immunize . . . . . . . . . . . . . . . . . 12
1.3 Immunizing Cron Jobs . . . . . . . . . . . . . . . . . . . . . . . 13
1.4 Immunizing Network Applications . . . . . . . . . . . . . . . . . . 13
2Prole Components and Syntax 19
2.1 Breaking a Novell AppArmor Prole into Its Parts . . . . . . . . . . . 19
2.2 #include Statements ...................... 21
2.3 Capability Entries (POSIX.1e) . . . . . . . . . . . . . . . . . . . . 22
3Building and Managing Proles With YaST 23
3.1 Adding a Prole Using the Wizard . . . . . . . . . . . . . . . . . . 25
3.2 Manually Adding a Prole . . . . . . . . . . . . . . . . . . . . . 32
3.3 EditingProles.......................... 33
3.4 DeletingaProle......................... 38
3.5 Updating Proles from Log Entries . . . . . . . . . . . . . . . . . . 39
3.6 Managing Novell AppArmor and Security Event Status . . . . . . . . . 40
4Building Proles via the Command Line 45
4.1 Checking the AppArmor Module Status . . . . . . . . . . . . . . . 45
4.2 Building Novell AppArmor Proles . . . . . . . . . . . . . . . . . . 47
4.3 Adding or Creating a Novell AppArmor Prole . . . . . . . . . . . . 48
4.4 Editing a Novell AppArmor Prole . . . . . . . . . . . . . . . . . . 48

4.5 Deleting a Novell AppArmor Prole . . . . . . . . . . . . . . . . . 48
4.6 Two Methods of Proling . . . . . . . . . . . . . . . . . . . . . . 49
4.7 Pathnames and Globbing . . . . . . . . . . . . . . . . . . . . . . 68
4.8 File Permission Access Modes . . . . . . . . . . . . . . . . . . . . 69
4.9 Important Filenames and Directories . . . . . . . . . . . . . . . . . 73
5Proling Your Web Applications Using ChangeHat 75
5.1 ApacheChangeHat........................ 76
5.2 Conguring Apache for mod_apparmor . . . . . . . . . . . . . . . 83
6Managing Proled Applications 87
6.1 Monitoring Your Secured Applications . . . . . . . . . . . . . . . . 87
6.2 Conguring Security Event Notication . . . . . . . . . . . . . . . . 88
6.3 Conguring Reports . . . . . . . . . . . . . . . . . . . . . . . . 91
6.4 Reacting to Security Event Rejections . . . . . . . . . . . . . . . . 110
6.5 Maintaining Your Security Proles . . . . . . . . . . . . . . . . . 111
7Support 113
7.1 Updating Novell AppArmor Online . . . . . . . . . . . . . . . . . 113
7.2 Using the Man Pages . . . . . . . . . . . . . . . . . . . . . . . 113
7.3 For More Information . . . . . . . . . . . . . . . . . . . . . . 115
7.4 Troubleshooting......................... 116
7.5 Reporting Bugs for AppArmor . . . . . . . . . . . . . . . . . . . 117
ABackground Information on AppArmor Proling 119
BGNU Licenses 121
B.1 GNU General Public License . . . . . . . . . . . . . . . . . . . . 121
B.2 GNU Free Documentation License . . . . . . . . . . . . . . . . . 129
Glossary 139

About This Guide
Novell® AppArmor is designed to provide easy-to-use application security for both
servers and workstations. Novell AppArmor is an access control system that lets you
specify per program which les the program may read, write, and execute. AppArmor
secures applications by enforcing good application behavior without relying on attack
signatures, so can prevent attacks even if they are exploiting previously unknown vul-
nerabilities.
Novell AppArmor consists of:
• A library of AppArmor proles for common Linux* applications describing what
les the program needs to access.
• A library of AppArmor prole foundation classes (prole building blocks) needed
for common application activities, such as DNS lookup and user authentication.
• A tool suite for developing and enhancing AppArmor proles, so that you can
change the existing proles to suit your needs and create new proles for your own
local and custom applications.
• Several specially modied applications that are AppArmor enabled to provide en-
hanced security in the form of unique subprocess connement, including Apache
and Tomcat.
• The Novell AppArmor–loadable kernel module and associated control scripts to
enforce AppArmor policies on your openSUSE™ system.
This guide covers the following topics:
Immunizing Programs
Describes the operation of Novell AppArmor and describes the types of programs
that should have Novell AppArmor proles created for them.
Prole Components and Syntax
Introduces the prole components and syntax.
Building and Managing Proles With YaST
Describes how to use the AppArmor YaST modules to build, maintain and update
proles.

Building Proles via the Command Line
Describes how to use the AppArmor command line tools to build, maintain and
update proles.
Proling Your Web Applications Using ChangeHat
Enables you to create subproles for the Apache Web server that allow you to
tightly conne small sections of Web application processing.
Managing Proled Applications
Describes how to perform Novell AppArmor prole maintenance, which involves
tracking common issues and concerns.
Support
Indicates support options for this product.
Glossary
Provides a list of terms and their denitions.
1 Feedback
We want to hear your comments and suggestions about this manual and the other doc-
umentation included with this product. Please use the User Comments feature at the
bottom of each page of the online documentation and enter your comments there.
2 Documentation Conventions
The following typographical conventions are used in this manual:
•/etc/passwd: lenames and directory names
•placeholder: replace placeholder with the actual value
•PATH: the environment variable PATH
•ls,--help: commands, options, and parameters
•user: users or groups
vi Novell AppArmor Administration Guide

•Alt,Alt +F1: a key to press or a key combination; keys are shown in uppercase as
on a keyboard
•File,File →Save As: menu items, buttons
•Dancing Penguins (Chapter Penguins, ↑Reference): This is a reference to a chapter
in another book.
3 Source Code
The source code of openSUSE is publicly available. To download the source code,
proceed as outlined under http://www.novell.com/products/suselinux/
source_code.html. If requested we send you the source code on a DVD. We need
to charge a $15 or €15 fee for creation, handling and postage. To request a DVD of the
source code, send an e-mail to [email protected] [mailto:sourcedvd@suse
.de] or mail the request to:
SUSE Linux Products GmbH
Product Management openSUSE
Maxfeldstr. 5
D-90409 Nürnberg
Germany
About This Guide vii

1
Immunizing Programs
Novell® AppArmor provides immunization technologies that protect applications from
the inherent vulnerabilities they possess. After installing Novell AppArmor, setting up
Novell AppArmor proles, and rebooting the computer, your system becomes immu-
nized because it begins to enforce the Novell AppArmor security policies. Protecting
programs with Novell AppArmor is referred to as immunizing.
Novell AppArmor sets up a collection of default application proles to protect standard
Linux services. In order to protect other applications, use the Novell AppArmor tools
to create proles for the applications that you want protected. This chapter introduces
the philosophy of immunizing programs. Proceed to Chapter 2, Prole Components
and Syntax (page 19), Chapter 3, Building and Managing Proles With YaST (page 23),
or Chapter 4, Building Proles via the Command Line (page 45) if you are ready to
build and manage Novell AppArmor proles.
Novell AppArmor provides streamlined access control for network services by specifying
which les each program is allowed to read, write, and execute. This ensures that each
program does what it is supposed to do and nothing else. Novell AppArmor quarantines
programs to protect the rest of the system from being damaged by a compromised
process.
Novell AppArmor is a host intrusion prevention, or mandatory access control scheme.
Previously, access control schemes were centered around users because they were built
for large timeshare systems. Alternatively, modern network servers largely do not permit
users to log in, but instead provide a variety of network services for users, such as Web,
mail, le, and print. Novell AppArmor controls the access given to network services
and other programs to prevent weaknesses from being exploited.
Immunizing Programs 9

TIP: Background Information for Novell AppArmor
To get a more in-depth overview of AppArmor and the overall concept behind
it, refer to Appendix A, Background Information on AppArmor Proling
(page 119).
1.1 Introducing the AppArmor
Framework
The following section provides you with a very basic understanding of what is happening
“behind the scenes” (and under the hood of the YaST interface) when you run App-
Armor.
An AppArmor prole is a plain text le containing path entries and access permissions,
see Section 2.1, “Breaking a Novell AppArmor Prole into Its Parts” (page 19) for a
detailed reference prole. The directives contained in this text le are then enforced
by the AppArmor routines to quarantine the process/program.
The following tools interact in the building and enforcement of AppArmor proles and
policies:
aa-unconned
aa-unconned detects any application running on your system that listens for net-
work connections and is not protected by an AppArmor prole. Refer to Section
“aa-unconned—Identifying Unprotected Processes” (page 67) for detailed infor-
mation on this tool.
aa-autodep
aa-autodep creates a basic skeleton of a prole that needs to be eshed out before
it is put to productive use. The resulting prole is loaded and put into complain
mode, reporting any behavior of the application that is not (yet) covered by App-
Armor rules. Refer to Section “aa-autodep—Creating Approximate Proles”
(page 52) for detailed information on this tool.
aa-genprof
aa-genprof generates a basic prole and asks you to rene this prole by executing
the application and thus generating log events that need to be taken care of by
10 Novell AppArmor Administration Guide