Book Image

SELinux System Administration - Second Edition

By : Sven Vermeulen
Book Image

SELinux System Administration - Second Edition

By: Sven Vermeulen

Overview of this book

Do you have the crucial job of protecting your private and company systems from malicious attacks and undefined application behavior? Are you looking to secure your Linux systems with improved access controls? Look no further, intrepid administrator! This book will show you how to enhance your system’s secure state across Linux distributions, helping you keep application vulnerabilities at bay. This book covers the core SELinux concepts and shows you how to leverage SELinux to improve the protection measures of a Linux system. You will learn the SELinux fundamentals and all of SELinux’s configuration handles including conditional policies, constraints, policy types, and audit capabilities. These topics are paired with genuine examples of situations and issues you may come across as an administrator. In addition, you will learn how to further harden the virtualization offering of both libvirt (sVirt) and Docker through SELinux. By the end of the book you will know how SELinux works and how you can tune it to meet your needs.
Table of Contents (16 chapters)
SELinux System Administration - Second Edition
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface

SELinux and PAM


With all the information about SELinux users and roles, we have not touched upon how exactly applications are able to create and assign a SELinux context to a user.

Assigning contexts through PAM

End users log in to a Linux system through either a login process (triggered through a getty process), a networked service (for example, the OpenSSH daemon), or through a graphical login manager (xdm, kdm, gdm, slim, and so on).

These services are responsible for switching our effective user ID (upon successful authentication, of course) so that we are not logged on to the system as the root user. In the case of SELinux systems, these processes also need to switch the SELinux user (and role) accordingly, as otherwise, the context will be inherited from the service, which is obviously wrong for any interactive session.

In theory, all these applications can be made fully SELinux aware, linking with the SELinux user space libraries to get information about Linux mappings and SELinux users...