[Lxc-users] Hard links to fifos not permitted in ephemeral containers? (was: Re: selinux trouble in lxc?)

[Serge Hallyn]

Quoting Dan Kegel (dank at kegel.com):
> On Fri, Sep 7, 2012 at 4:01 PM, Dan Kegel <dank at kegel.com> wrote:
> >>   mkfifo /tmp/fifo
> >>   ln /tmp/fifo /tmp/fifo2
> >> fails with "operation not permitted".
> >>
> > Aha.  Starting with 'lxc-start' yields a system which can do the ln.
> > Starting with 'lxc-start-ephemeral' yields a system which can't.
> > Has nothing to do with /tmp.
> >
> > Is overlayfs at fault?
> 
> I see there are several rumored sources of restrictions on hardlinks, e.g.
> https://lkml.org/lkml/2011/5/19/384
> https://lkml.org/lkml/2012/2/21/397
> 
> And I see this is a known issue:
> http://comments.gmane.org/gmane.linux.ubuntu.devel/34948
> 
> Happily, using the -U aufs option to lxc-start-ephemeral seems to work
> around the problem, at least in my little test.  I'll know soon if it fixes
> my real system.
> 
> But I was not able to find a bug for this issue in launchpad.  Should
> I file one?

There are several other bugs in overlayfs which are not hurriedly
getting fixed.  If you have a testcase to show that it's definately
an overlayfs bug, you might just take it o lkml.

But yeah, filing a bug against 'linux' (the kernel package) saying
it's an overlayfs bugs would be good.

thanks,
-serge