btrfs snapshots, rollbacks

[Chris Murphy]

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?

> 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.


Chris Murphy