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 12

  1. When SELinux Booleans are changed through the /sys/fs/selinux/booleans filesystem, the changes are not automatically committed. For that to occur, you also need to write the value 1 into /sys/fs/selinux/commit_pending_bools.
  2. The sesearch command is used to query the active policy, and can be used to query the impact of SELinux Booleans as well. Add the -b <boolean> argument to limit the query to rules that are influenced by the SELinux Boolean.
  3. When an SELinux policy module is loaded, it is assigned a priority that tells the system whether it should be the active module. Administrators can load new modules at a higher priority to test them out, and remove them again, without risking that no proper SELinux rules are active on the system at all.

    Likewise, administrators can load a policy at a lower priority, ensuring that it is not yet active, and later on remove the module at the higher priority so that the newly loaded policy becomes active.

    This is unlike...