Book Image

SELinux System Administration, Third Edition - Third Edition

By : Sven Vermeulen
Book Image

SELinux System Administration, Third Edition - Third Edition

By: Sven Vermeulen

Overview of this book

Linux is a dominant player in many organizations and in the cloud. Securing the Linux environment is extremely important for any organization, and Security-Enhanced Linux (SELinux) acts as an additional layer to Linux system security. SELinux System Administration covers basic SELinux concepts and shows you how to enhance Linux system protection measures. You will get to grips with SELinux and understand how it is integrated. As you progress, you’ll get hands-on experience of tuning and configuring SELinux and integrating it into day-to-day administration tasks such as user management, network management, and application maintenance. Platforms such as Kubernetes, system services like systemd, and virtualization solutions like libvirt and Xen, all of which offer SELinux-specific controls, will be explained effectively so that you understand how to apply and configure SELinux within these applications. If applications do not exert the expected behavior, you’ll learn how to fine-tune policies to securely host these applications. In case no policies exist, the book will guide you through developing custom policies on your own. By the end of this Linux book, you’ll be able to harden any Linux system using SELinux to suit your needs and fine-tune existing policies and develop custom ones to protect any app and service running on your Linux systems.
Table of Contents (22 chapters)
1
Section 1: Using SELinux
8
Section 2: SELinux-Aware Platforms
14
Section 3: Policy Management

Comparing policies

Until now, we've analyzed a single policy set, finding the domain transitions and information flow paths. The commands and applications we've used all focus on this single-policy analysis. Another important analysis is to compare two policies. Policy developers can use this to compare a new policy with an old one, or to compare two system policies to see what additional rules have been added by the administrator.

Using sediff to compare policies

The sediff tool looks at the differences between two policy files and reports those to the user. It is often not sensible to use this against completely different policies, but is powerful for finding slight differences between policies, which can assist in troubleshooting issues across different systems.

A common use case for sediff is to validate that a source-built policy file is the same as the distribution-provided binary policy file. Administrators can then be certain that the source code they&apos...