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

Running applications without restrictions

The default behavior in many Linux distributions is to run new applications through unconfined domains. These are specially crafted domains that, while still being controlled by SELinux, are designed to have very, very broad permissions granted. You can compare such unconfined domains with a firewall that allows any possible flow: while the firewall is running, it is hardly doing any enforcement.

There is, however, another approach possible as well, namely, running an application as a permissive domain. Unlike unconfined domains, permissive domains are not enforced through SELinux: everything the domain does is allowed, even though SELinux might log every violation. We briefly touched upon permissive domains in Chapter 3, Understanding SELinux Decisions and Logging.

Let's first look at unconfined domains and how administrators can modify system configuration to apply unconfined domains to other applications, or remove applications...