Book Image

SELinux System Administration. - Second Edition

Book Image

SELinux System Administration. - Second Edition

Overview of this book

Do you have the crucial job of protecting your private and company systems from malicious attacks and undefined application behavior? Are you looking to secure your Linux systems with improved access controls? Look no further, intrepid administrator! This book will show you how to enhance your system’s secure state across Linux distributions, helping you keep application vulnerabilities at bay. This book covers the core SELinux concepts and shows you how to leverage SELinux to improve the protection measures of a Linux system. You will learn the SELinux fundamentals and all of SELinux’s configuration handles including conditional policies, constraints, policy types, and audit capabilities. These topics are paired with genuine examples of situations and issues you may come across as an administrator. In addition, you will learn how to further harden the virtualization offering of both libvirt (sVirt) and Docker through SELinux. By the end of the book you will know how SELinux works and how you can tune it to meet your needs.
Table of Contents (16 chapters)
SELinux System Administration - Second Edition
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface

Enhancing SELinux policies


Not all situations can be perfectly defined by policy writers. At times, we will need to make modifications to the SELinux policy. As long as the changes involve adding rules, we can create additional SELinux modules to enhance the policy. If the change is more intrusive, we might need to remove an existing SELinux module and replace it with an updated one.

Listing policy modules

SELinux policy modules are, as mentioned at the beginning of this book, sets of SELinux rules that can be loaded and unloaded. These modules, with .pp or .cil suffixes, can be loaded and unloaded as needed by the administrator. Once loaded, the policy module is part of the SELinux policy store and will be loaded even after a system reboot.

To list currently loaded SELinux policy modules, it is recommended to use the semodule command. Depending on the version of the SELinux user space tools (in this case, the version of the policycoreutils package), listing modules will show module versions...