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 4

  1. The most common option is -Z, and is supported by tools such as ls, mv, and ps. The same character is also used by systemd's tmpfiles application to explicitly set SELinux contexts on resources. However, while this is the most commonly used option, not all tools follow this convention, so we recommend to always consult the tool's help or manual page.
  2. In most cases, the context is stored as an extended attribute of the file or directory within the filesystem. This extended attribute is the security.selinux attribute, and can be queried with tools such as getfattr or stat.

    However, not all filesystems support extended attributes. In that case, the SELinux context is obtained through the mount options of that filesystem, and all resources on the filesystem then use the same context.

  3. The chcon application directly alters the SELinux context for a file, but does not adjust the system's file context definitions. If, at any point in time, the system or...