Working on a new selinuxnode VM


Sven Vermeulen Sat 23 February 2013

A long time ago, I made a SELinux enabled VM for people to play with, displaying a minimal Gentoo installation, including the hardening features it supports (PIE/PIC toolchain, grSecurity, PaX and SELinux). I'm currently trying to create a new one, which also includes IMA/EVM, but it looks like I still have many things to investigate further...

First of all, I notice that many SELinux domains want to use the mknod capability, even for domains of which I have no idea whatsoever why they need it. I don't notice any downsides though, and running in permissive mode doesn't change the domain behavior. But still, I'm reluctant to mark them dontaudit as long as I'm not 100% sure.

Second, the gettys (I think it is the getty) result in a "Cannot change SELinux context: permission denied" error, even though everything is running in the right SELinux context. I still have to confirm if it really is the getty process or something else (the last run I had the impression it was a udev-related process). But there are no denials and no SELinux errors in the logs.

Third, during shutdown, many domains have problems accessing their PID files in /var/run (which is a link to /run). I most likely need to allow read privileges on all domains that have access to var_run_t towards the var_t symlinks. It isn't a problem per se (the processes still run correctly) but ugly as hell, and if you introduce monitoring it'll go haywire (as no PID files were either found, or were stale).

Also, EVM is giving me a hard time, not allowing me to change mode and ownership in files on /var/run. I have received some feedback from the IMA user list on this so it is still very much a work-in-progress.

Finally, the first attempt to generate a new VM resulted in a download of 817 MB (instead of the 158 MB of the previous release), so I still have to correct my USE flags and doublecheck the installed applications. Anyway, definitely to be continued. Too bad time is a scarce resource :-(