Why I (still) care about SELinux and its flaws

November 7, 2015

A perfectly sensible reaction to my series of disgruntlements is to ask why I still care enough to write about it. There is all sorts of ill-considered software out there in the world, and disabling SELinux is simple enough. I don't gripe about Ubuntu's AppArmor, for example (which we disable too). As it happens, there are two major reasons that I continue to care about SELinux.

First, the continued existence and popularity of SELinux drains the time and attention of people away from doing other, more usable security work. Linux needs security work of all sorts, including defenses against normal programs being compromised. In fact, the existence and theoretical purity and power of SELinux (and it being integrated into the kernel and major distributions) serves to block most explorations of more usable but more messy solutions. If you propose doing something, especially if you touch user-level programs, I expect that you'll get told 'SELinux already solves that (and better)'.

(If you want an idea of what such solutions might look like, look at the work OpenBSD is doing here with eg the tame()/pledge() system call and other related things.)

Or in short, SELinux is effectively a high stakes gamble with Linux security. People are betting on what is very close to mathematical security, which would be great if it worked but instead often leads to the total failure of SELinux's toxic mistake.

Second, increasingly SELinux is being advocated as a default thing for everyone to use as part of hardening Linux, not just as an extra add-on for the paranoid. This is not exactly a new development (it's why SELinux is the default in Red Hat Enterprise and Fedora), but my strong impression is that it's been ramping up these days (more and more people will loudly tell you that you're doing it wrong if you disable SELinux, for example). When SELinux is supposed to be for everyone, well, it affects me more and more; it's increasingly present and increasingly mandatory.

Also, as part of caring about the direction of Linux in general I care about something that is theoretically supposed to be the Linux answer for (user-level) security issues for everyone. If SELinux is Linux's security solution and I think it's a bad idea, every so often my irritation boils over and I write another blog entry here.

(Real, usable security is one of my hot buttons in general, as you may have either noticed or guessed.)

Written on 07 November 2015.
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Last modified: Sat Nov 7 00:33:02 2015
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