Book Image

SELinux System Administration - Second Edition

By : Sven Vermeulen
Book Image

SELinux System Administration - Second Edition

By: Sven Vermeulen

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

Switching SELinux on and off


This is perhaps a weird section to begin with, but disabling SELinux is a commonly requested activity. Some vendors do not support their application running on a platform that has SELinux enabled. System administrators are generally reluctant to use security controls they do not understand or find too complex to maintain. Luckily, this number is diminishing, and SELinux is also capable of selectively disabling its access controls for a part of the system rather than requiring us to completely disable it.

Setting the global SELinux state

SELinux supports three major states that it can be in: disabled, permissive, and enforcing. These states are set in the /etc/selinux/config file, through the SELINUX variable. Take a look at the current setting:

$ grep ^SELINUX= /etc/selinux/config
SELINUX=enforcing

When the system init process loads the SELinux policy, the SELinux code checks the state that the administrator has configured. The states are described as follows...