[systemd-devel] /run DoS

[Karel Zak]

On Sun, Apr 03, 2011 at 11:45:51PM +0200, Kay Sievers wrote:
> 2011/4/3 Lennart Poettering <mzerqung at 0pointer.de>:
> > On Sun, 03.04.11 23:28, Michał Piotrowski (mkkp4x4 at gmail.com) wrote:
> >
> >> > But for /dev/shm I see no quick fix... do you?
> >>
> >> Unfortunately not. No one foresaw that quota support on tmpfs will
> >> someday be useful :)
> >>
> >> >
> >> > I think we should fix either both or should wait for the proper fix by
> >> > the kernel.
> >>
> >> Can you temporarily fix one?
> >
> > Well, of course we could.
> >
> > But, think about it, what does this help? The vulnerability doesn't go
> > away by doing this, and we'd have a temporary hack in there, that we'd
> > have to remove later on again.
> 
> Systems who might run into problems with /dev/shm, can just add limits
> to /etc/fstab, and systemd will re-mount it and apply them.
> 
> There should really be a _proper_ solution some day, be it quota or
> something else. We have way too many /tmp-like dirs, where users can
> just leave their crap behind and cause problems. This is really
> nothing new with systemd.

 Wouldn't be possible to use namespaces (pam_namespace ?) and after
 user login create any private tmpfs (with explicitly defined size)?

 This allows to use the same path (e.g. /run/user) for all users, make
 the content of the directory invisible for other users and
 effectively control resources. All this is supported by kernel ;-)

    Karel

-- 
 Karel Zak  <kzak at redhat.com>
 http://karelzak.blogspot.com