Linux-based operating systems are built on an open-development model, which can afford organizations an early view of-and an opportunity to influence-the technologies and implementations that will eventually work their way into these companies’ infrastructures.
What’s more, these early looks extend beyond points on a presentation slide to comprise run-able code that’s gathered into fast-moving, community-supported Linux distributions that administrators can begin testing in advance of the long-lived, enterprise-oriented releases to come.
I examined the principal security-related developments in three such vanguard Linux distributions, Canonical’s Ubuntu Linux 8.10, Novell’s OpenSUSE 11.1 and Red Hat’s Fedora 10, all of which are now available in beta form.
Ubuntu Linux 8.10, which is slated for release at the end of October, ships with an encrypted private directory feature that enables users to store sensitive data securely without incurring the performance overhead of full-volume encryption.
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In my own tests with full-volume encryption in previous Ubuntu versions, I’ve noted processor overhead of about 20 to 30 percent during disk-intensive processes such as virtual machine image creation.
What’s more, full-disk encryption, unlocked by a single pass key, poses problems for multiuser machines, in which the disk unlocking is an all-or-nothing proposition, as opposed to a user-by-user measure.
As implemented in Ubuntu 8.10, the encrypted private directory feature creates a folder-labeled “Private”-in users’ home directories. The system automatically encrypts files placed in this directory and unlocks the directory upon user log-on.
In my tests, I could broaden the range of home directory folders that the system protected by copying the folders to the Private location and leaving a symlink behind to allow my applications to continue accessing the protected files at their previous addresses.
As this feature now stands, it’s too roughly implemented to supplant full-volume encryption entirely-there’s no user interface at this point, and there’s the possibility that sensitive data could be pulled from a system’s unencrypted swap partition. I hope to see Ubuntu’s encryption feature set firmed up to include full-volume, Private folder and home directory encryption in time for the distribution’s next LTS (Long Term Support) release, which is currently scheduled for April 2010.
Access Control and Audit Tools
Version 11.1 of Novell’s OpenSUSE, which is the community-oriented sibling of the company’s more buttoned-down SUSE Linux Enterprise distributions, is slated for release at the beginning of December, complete with basic support for the SELinux mandatory access control system.
Novell’s embrace of SELinux has raised eyebrows in the Linux community because SELinux has been primarily a Red Hat-driven initiative over the past few years. For its part, Novell has been pushing an alternative access control scheme, called AppArmor, which was the fruit of Novell’s 2005 acquisition of Immunix.
Novell has often called out Red Hat and SELinux for the system’s complexity-a Linux system secured with SELinux carries policies that closely govern the specific actions and rights of every user, file and application on a machine, and these policies can be very difficult to create, review and troubleshoot.
However, as implemented by Red Hat, SELinux can be enabled with a targeted policy that tightly controls certain applications while leaving others to the supervision of traditional Linux access controls.
OpenSUSE 11.1 will ship with only basic support for SELinux-AppArmor remains the suggested security enhancement mechanism for the distributions-but according to Novell, the addition of basic SELinux support will allow customers who have adopted SELinux to migrate their systems to Novell’s Linux operating system.
Version 10 of Red Hat’s Fedora Linux distribution, which is scheduled for release at the end of November, is set to ship with a new security audit and intrusion prevention tool.
Between this new tool, Fedora’s support for full-volume encryption at install time (a feature that Ubuntu also offers but OpenSUSE lacks) and Fedora’s well-implemented SELinux subsystem, Red Hat has delivered the most well-rounded complement of security features available on any current Linux distribution.
The new audit utility, which Red Hat is calling Sectool, provides a set of system tests for detecting configuration issues regarding permissions, firewall rules and the status of other system security features. In addition, Sectool offers administrators a framework for writing their own tests in Bash, Python or other scripting languages.
As implemented in Fedora 10, Sectool organizes sets of tests into five security levels, with ascending security strictness: Naive, Desktop, Network, Server or Paranoid.
I ran the graphical version of the Sectool utility (there’s also a command-line version) on a Fedora 10 beta installation at a few of the security levels, and the tool responded with errors, problems that I should fix and warnings, or less serious informational messages.
The tool offered enough information in the error messages to point me in the right direction toward resolving the issues, but this functionality could be better integrated with the system’s configuration tools.
eWEEK Labs Executive Editor Jason Brooks can be reached at [email protected]