btrfs snapshots, rollbacks

[Hubert Kario]

----- Original Message -----
> From: "Chris Murphy" <lists at colorremedies.com>
> To: "Hubert Kario" <hkario at redhat.com>
> Cc: security at lists.fedoraproject.org
> Sent: Thursday, 13 February, 2014 5:02:57 PM
> Subject: Re: btrfs snapshots, rollbacks
> 
> 
> 
> 
> On Feb 13, 2014, at 5:11 AM, Hubert Kario <hkario at redhat.com> wrote:
> 
> > As long as the old /bin and /usr/bin are not part of PATH, I'd say we've
> > done our job. We can't protect the user from shooting himself in the foot
> > in all cases.
> 
> The snapshots aren't in PATH. However, the yum plugin would put them at
> 
> /yum_<datetime>/bin   /yum_<datetime>/usr/bin
> 
> Snapper puts them in
> 
> /.snapshots/<#>/snapshot/bin   /.snapshots/<#>/snapshot/usr/bin
> 
> I'm not sure what you mean by the user shooting himself - these locations
> aren't up to the user with these tools. And installer behavior can limit
> user choice as to where the snapshots can be placed.
> 
> So, is the ability to hide snapshots in an unmounted portion of the (on-disk)
> file system valuable from a security perspective? Or it it trivial?

I would consider it trivial.
 
> > The logs are a different matter, we should aim to preserve them. Dunno
> > where
> > journald is in this picture (binary log forward and backward
> > compatibility).
> 
> If by preserve you mean a single contiguous log location, then that implies
> needing a subvolume for logs. For example:
> 
> http://lists.freedesktop.org/archives/systemd-devel/2014-January/016253.html
> 
> I have implemented this and it appears to work, although probably it should
> be a log subvolume mounted at /var/log so that all logs can be kept
> contiguous, not just the journal.

Yes, that's what I was thinking about.

If we're going to support update rollback through snapshots I think that
/var/log should be kept separate in default install.

-- 
Regards,
Hubert Kario
Quality Engineer, QE BaseOS Security team
http://wiki.brq.redhat.com/hkario
Email: hkario at redhat.com
Web: www.cz.redhat.com
Red Hat Czech s.r.o., Purkyňova 99/71, 612 45, Brno, Czech Republic