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

Chapter 16: Developing Policies with SELinux CIL

While the reference policy is the most frequently used language and development style for SELinux policies, the Common Intermediate Language (CIL) is a powerful, but more low-level language construct to use to develop SELinux policies. Low-level as it might be though, it is still very much readable and well supported, as SELinux tools will use CIL under the hood when using other languages.

Since CIL is the main language used, we know it can be used to build entire policies. Sadly, there are no supporting constructs available for developers to use, unlike the reference policy. However, we can still learn how to customize the current policy, creating specific definitions that are not possible with the more common reference policy, and even build a complete application policy if we choose.

In this chapter, we're going to cover the following main topics:

  • Introducing CIL
  • Creating fine-grained definitions
  • Building...