linux-kernel - Re: noisy selinux messages on tmpfs mount.

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Date:	Fri, 9 Jan 2015 14:13:29 -0500
From:	Dave Jones <davej@...emonkey.org.uk>
To:	Stephen Smalley <stephen.smalley@...il.com>
Cc:	Paul Moore <pmoore@...hat.com>, selinux <selinux@...ho.nsa.gov>,
	James Morris <james.l.morris@...cle.com>,
	Stephen Smalley <sds@...ch.ncsc.mil>,
	Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: noisy selinux messages on tmpfs mount.

On Fri, Jan 09, 2015 at 08:06:49AM -0500, Stephen Smalley wrote:
 
 > On Thu, Jan 8, 2015 at 2:39 PM, Paul Moore <pmoore@...hat.com> wrote:
 > > On Thursday, January 08, 2015 02:34:57 PM Paul Moore wrote:
 > >> On Thursday, January 08, 2015 02:08:22 PM Dave Jones wrote:
 > >> > systemd has started mounting a tmpfs in /run/user/<uid> every time a
 > >> > session begins.  So after ssh'ing into a box a number of times, dmesg
 > >> > looks like this..
 > >> >
 > >> > [...] SELinux: initialized (dev tmpfs, type tmpfs), uses transition SIDs
 > >> > [...] SELinux: initialized (dev tmpfs, type tmpfs), uses transition SIDs
 > >>
 > >> {snip}
 > >>
 > >> > What's a good solution to stopping this spew ? printk_once doesn't seem
 > >> > like a good fit, in case someone is doing different labelling behaviours
 > >> > between mounts.
 > >> >
 > >> > Could we only print it if the mount is being done with non-default
 > >> > behaviour perhaps?
 > >>
 > >> I'm very curious to hear Stephen's opinion on the issue, but I wonder how
 > >> much this would honestly impact us if we removed this message in the case
 > >> where we mount the filesystem with a known labeling behavior.
 >
 > We already reduced that message to KERN_DEBUG.  Is that not sufficient?

That doesn't really help with the flooding of dmesg, so no.
I should also note that it's not just logging in that creates a new
session, it also seems to be getting triggered by cron jobs, or
whatever the systemd replacement is.

	Dave

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