Re: [rfc] fcntl: Add F_GETOWNER_UIDS option

From: Serge E. Hallyn
Date: Tue Mar 27 2012 - 18:29:04 EST

Quoting Cyrill Gorcunov (gorcunov@xxxxxxxxxx):
> On Tue, Mar 27, 2012 at 05:25:34PM +0200, Oleg Nesterov wrote:
> > user_ns_map_uid() should translate uid_t from one namespace to another,
> > in this case the namespace is the same.
> >
> > user_ns_map_uid(cred->user_ns, cred) must be the identical mapping,
> > no matter how we change the implementation.
> >
> > What I think you need is
> > user_ns_map_uid(current_user_ns(), filp->f_owner.cred), the only
> > problem is that f_owner.cred doesn't exist.
> >
> Hmm, I was confused by likely() in user_ns_map_uid. But indeed, I think
> you're so right. Is there some reason why we can't carry f_owner.cred
> pointer?

We would need that for this, yes. However, Eric is working on a new
patchset which changes the cross-userns uid mappings. I think it's
worth simply leaving a comment that this will need to be addressed,
and leave in the unconverted uid.

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