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

User-oriented SELinux contexts

Once logged in to a system, our user will run inside a certain context. This user context defines the rights and privileges that we, as a user, have on the system. The command to obtain current user information, id, also supports displaying the current SELinux context information:

$ id -Z
unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023

On SELinux systems with a targeted policy type, chances are very high that all users are logged in as unconfined_u (the first part of the context). On more restricted systems, the user can be user_u (regular restricted users), staff_u (operators), sysadm_u (system administrators), or any of the other SELinux users.

The SELinux user defines the roles that the user can switch to. SELinux roles themselves define the application domains that the user can use. By default, a fixed number of SELinux users are available on the system, but administrators can create additional SELinux users. It is also the administrator...