Using nVidia with SELinux

Yesterday I've switched to the gentoo-sources kernel package on Gentoo Linux. And with that, I also attempted (succesfully) to use the propriatary nvidia drivers so that I can enjoy both a smoother 3D experience while playing minecraft, as well as use the CUDA support so I don't need to use cloud-based services for small exercises.

The move to nvidia was quite simple, as the nvidia-drivers wiki article on the Gentoo wiki was quite easy to follow.

more ...

Switch to Gentoo sources

You've might already read it on the Gentoo news site, the Hardened Linux kernel sources are removed from the tree due to the grsecurity change where the grsecurity Linux kernel patches are no longer provided for free. The decision was made due to supportability and maintainability reasons.

That doesn't mean that users who want to stick with the grsecurity related hardening features are left alone. Agostino Sarubbo has started providing sys-kernel/grsecurity-sources for the users who want to stick with it, as it is based on minipli's unofficial patchset. I seriously hope that the patchset will continue to be maintained and, who knows, even evolve further.

Personally though, I'm switching to the Gentoo sources, and stick with SELinux as one of the protection measures. And with that, I might even start using my NVidia graphics card a bit more, as that one hasn't been touched in several years (I have an Optimus-capable setup with both an Intel integrated graphics card and an NVidia one, but all attempts to use nouveau for the one game I like to play - minecraft - didn't work out that well).

more ...

SELinux System Administration, 2nd Edition

While still working on a few other projects, one of the time consumers of the past half year (haven't you noticed? my blog was quite silent) has come to an end: the SELinux System Administration - Second Edition book is now available. With almost double the amount of pages and a serious update of the content, the book can now be bought either through Packt Publishing itself, or the various online bookstores such as Amazon.

With the holidays now approaching, I hope to be able to execute a few tasks within the Gentoo community (and of the Gentoo Foundation) and get back on track. Luckily, my absence was not jeopardizing the state of SELinux in Gentoo thanks to the efforts of Jason Zaman.

more ...


Getting su to work in init scripts

While developing an init script which has to switch user, I got a couple of errors from SELinux and the system itself:

~# rc-service hadoop-namenode format
Authenticating root.
 * Formatting HDFS ...
su: Authentication service cannot retrieve authentication info
(Ignored)
more ...


Using multiple OpenSSH daemons

I administer a couple of systems which provide interactive access by end users, and for this interactive access I position OpenSSH. However, I also use this for administrative access to the system, and I tend to have harder security requirements for OpenSSH than most users do.

For instance, on one system, end users with a userid + password use the sFTP server for publishing static websites. Other access is prohibited, so I really like this OpenSSH configuration to use chrooted users, internal sftp support, whereas a different OpenSSH is used for administrative access (which is only accessible by myself and some trusted parties).

more ...

Doing away with interfaces

CIL is SELinux' Common Intermediate Language, which brings on a whole new set of possibilities with policy development. I hardly know CIL but am (slowly) learning. Of course, the best way to learn is to try and do lots of things with it, but real-life work and time-to-market for now forces me to stick with the M4-based refpolicy one.

Still, I do try out some things here and there, and one of the things I wanted to look into was how CIL policies would deal with interfaces.

more ...

Why we do confine Firefox

If you're a bit following the SELinux development community you will know Dan Walsh, a Red Hat security engineer. Today he blogged about CVE-2015-4495 and SELinux, or why doesn't SELinux confine Firefox. He should've asked why the reference policy or Red Hat/Fedora policy does not confine Firefox, because SELinux is, as I've mentioned before, not the same as its policy.

In effect, Gentoo's SELinux policy does confine Firefox by default. One of the principles we focus on in Gentoo Hardened is to develop desktop policies in order to reduce exposure and information leakage of user documents. We might not have the manpower to confine all desktop applications, but I do think it is worthwhile to at least attempt to do this, even though what Dan Walsh mentioned is also correct: desktops are notoriously difficult to use a mandatory access control system on.

more ...

Can SELinux substitute DAC?

A nice twitter discussion with Erling Hellenäs caught my full attention later when I was heading home: Can SELinux substitute DAC? I know it can't and doesn't in the current implementation, but why not and what would be needed?

SELinux is implemented through the Linux Security Modules framework which allows for different security systems to be implemented and integrated in the Linux kernel. Through LSM, various security-sensitive operations can be secured further through additional access checks. This criteria was made to have LSM be as minimally invasive as possible.

more ...