Novell APPARMOR 2.1 - Instruction Manual

AppArmor

www.novell.com2.1

September27,2007 Novell AppArmor Administration Guide

Novell AppArmor Administration Guide

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”.

SUSE®, openSUSE®, the openSUSE® logo, Novell®, the Novell® logo, the N® 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. A

trademark symbol (® , ™, etc.) denotes a Novell trademark; an asterisk (*) denotes a third-party

trademark.

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 1

1.1 Introducing the AppArmor Framework . . . . . . . . . . . . . . . . 2

1.2 Determining Programs to Immunize . . . . . . . . . . . . . . . . . . 4

1.3 Immunizing cron Jobs . . . . . . . . . . . . . . . . . . . . . . . . 5

1.4 Immunizing Network Applications . . . . . . . . . . . . . . . . . . 5

2Prole Components and Syntax 11

2.1 Breaking a Novell AppArmor Prole into Its Parts . . . . . . . . . . . 12

2.2 #include Statements ...................... 21

2.3 Capability Entries (POSIX.1e) . . . . . . . . . . . . . . . . . . . . 22

2.4 Using the Local AppArmor Prole Repository . . . . . . . . . . . . . 22

2.5 Using the External AppArmor Prole Repository . . . . . . . . . . . . 23

2.6 Important Filenames and Directories . . . . . . . . . . . . . . . . . 25

3Building and Managing Proles with YaST 27

3.1 Adding a Prole Using the Wizard . . . . . . . . . . . . . . . . . . 29

3.2 Manually Adding a Prole . . . . . . . . . . . . . . . . . . . . . 37

3.3 EditingProles.......................... 38

3.4 DeletingaProle......................... 43

3.5 Updating Proles from Log Entries . . . . . . . . . . . . . . . . . . 44

3.6 Managing Novell AppArmor and Security Event Status . . . . . . . . . 45

4Building Proles from the Command Line 49

4.1 Checking the AppArmor Module Status . . . . . . . . . . . . . . . 49

4.2 Building AppArmor Proles . . . . . . . . . . . . . . . . . . . . . 51

4.3 Adding or Creating an AppArmor Prole . . . . . . . . . . . . . . . 52

4.4 Editing an AppArmor Prole . . . . . . . . . . . . . . . . . . . . 52

4.5 Deleting an AppArmor Prole . . . . . . . . . . . . . . . . . . . . 52

4.6 Two Methods of Proling . . . . . . . . . . . . . . . . . . . . . . 53

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 Conguring and Using the AppArmor Desktop Monitor Applet . . . . . 111

6.5 Reacting to Security Event Rejections . . . . . . . . . . . . . . . . 112

6.6 Maintaining Your Security Proles . . . . . . . . . . . . . . . . . 112

7Support 115

7.1 Updating Novell AppArmor Online . . . . . . . . . . . . . . . . . 115

7.2 Using the Man Pages . . . . . . . . . . . . . . . . . . . . . . . 115

7.3 For More Information . . . . . . . . . . . . . . . . . . . . . . 117

7.4 Troubleshooting......................... 118

7.5 Reporting Bugs for AppArmor . . . . . . . . . . . . . . . . . . . 124

ABackground Information on AppArmor Proling 127

BGNU Licenses 129

B.1 GNU General Public License . . . . . . . . . . . . . . . . . . . . 129

B.2 GNU Free Documentation License . . . . . . . . . . . . . . . . . 132

Glossary 137

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 it can prevent attacks even if they are exploiting previously unknown

vulnerabilities.

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 from 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, ↑Another Manual): This is a reference to a

chapter in another manual.

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

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. To protect other applications, use the Novell AppArmor tools to create

proles for the applications that you want protected. This chapter introduces the philos-

ophy of immunizing programs. Proceed to Chapter 2, Prole Components and Syntax

(page 11), Chapter 3, Building and Managing Proles with YaST (page 27), or Chap-

ter 4, Building Proles from the Command Line (page 49) 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, and which type of

network it is allowed to access. 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 servers. Novell AppArmor controls the access given to network

services and other programs to prevent weaknesses from being exploited.

Immunizing Programs 1

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 127).

1.1 Introducing the AppArmor

Framework

This section provides a very basic understanding of what is happening “behind the

scenes” (and under the hood of the YaST interface) when you run AppArmor.

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 12) for a

detailed reference prole. The directives contained in this text le are then enforced

by the AppArmor routines to quarantine the process or 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 73) for detailed infor-

mation about 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 56) for detailed information about this tool.

aa-genprof

aa-genprof generates a basic prole and asks you to rene this prole by executing

the application, generating log events that need to be taken care of by AppArmor

policies. You are guided through a series of questions to deal with the log events

2Novell AppArmor Administration Guide

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