Re: [PATCH] devpts: Make ptmx be owned by the userns owner instead of userns-local 0

From: Andy Lutomirski
Date: Tue Mar 15 2016 - 14:21:48 EST

On Mar 14, 2016 1:35 AM, "Serge Hallyn" <serge.hallyn@xxxxxxxxxx> wrote:
> Quoting Andy Lutomirski (luto@xxxxxxxxxx):
> > We used to have ptmx be owned by the inner uid and gid 0. Change
> > this: if the owner and group are both mapped but are not both 0,
> > then use the owner instead.
> >
> > For container-style namespaces (LXC, etc), this should have no
> > effect -- UID 0 is will either be the owner or will be unmapped.
> This doesn't seem right - it's often the case that the owner is mapped
> in as non-0 uid, safe or not. The actual namespace root uid should be
> the owner (so long as it exists).
> Why not reverse the cases? If 0 is not mapped, then check whether the
> current_user_ns()->owner is mapped?

Good point, and less chance of breakage that way as well.