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

Creating fine-grained definitions

Throughout this book, most small SELinux policy adjustments have been made using CIL. These are small, fine-grained definitions that require little development effort, and have the benefit of being directly loadable.

Depending on roles or types

The CIL language requires some order in how types or roles are linked in the policy. Sometimes, when we develop CIL policies, the order of the types might not be addressed properly.

To work around this issue, a default attribute called cil_gen_require is used. When types or roles are assigned to the cil_gen_require attribute, they are automatically linked correctly in the policy. This is not a CIL requirement though, but a convention that the SELinux utilities use.

The attribute actually exists twice, once as a type attribute and once as a role attribute. They might have the same name, but are two different attributes:

(roleattributeset cil_gen_require system_r)
(typeattributeset cil_gen_require...