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 7

  1. The unit files in /usr/lib/systemd/system are managed by the Linux distribution itself. Whenever a new update to the software is deployed on the system, these files are overwritten.

    Modifications to unit files should be placed in /etc/systemd/system instead, as they overrule the settings in /usr/lib/systemd, and software deployments should not place any of their unit files in that location.

  2. The application is tmpfiles, and is part of the systemd suite. To have it reset a context, a configuration file has to be created (in /etc/tmpfiles.d for locally defined changes) and use the z directive (to reset the context of a single file) or the Z directive (to recursively set the context of an entire directory).
  3. The journalctl command allows filtering on variables that it obtained from the event itself. One of these variables is the SELinux context of the service that generated the event.

    To filter on a particular value, you use the variable name as an argument to the journalctl...