linux-kernel - Re: [rfc] fcntl: Add F_GETOWNER

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Date:	Wed, 28 Mar 2012 23:32:15 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Serge Hallyn <serge.hallyn@...onical.com>
Cc:	"Serge E. Hallyn" <serge@...lyn.com>,
	Cyrill Gorcunov <gorcunov@...nvz.org>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Pavel Emelyanov <xemul@...allels.com>
Subject: Re: [rfc] fcntl: Add F_GETOWNER_UIDS option

On 03/28, Serge Hallyn wrote:
>
> Quoting Oleg Nesterov (oleg@...hat.com):
> > On 03/28, Serge E. Hallyn wrote:
> > >
> > > If you want to
> > > just add the struct cred to the f_owner and do proper uid conversion,
> > > I'll support that too.  (Just grab a ref to the cred in
> > > fs/fcntl.c:f_modown(), and drop the ref in fs/file_table.c:__fput() ).
> >
> > In this case f_owner.*uid should go away, I guess.
>
> Yup.
>
> Which I guess is all the more reason *not* to do this unless we end up
> not going with Eric's userns mapping patchset (which is unlikely).

Agreed,

> > And sigio_perm()
> > should be unified with kill_ok_by_cred() somehow (modulo
> > security_file_send_sigiotask).
> >
> > Right?
>
> Maybe, but other differences include current being the signal sender in
> one and recipient in the other, and CAP_KILL being relevent in only
> one.

Yes, yes, sure. "current" is meaningless for sigio_perm().

That is why I asked, the "somehow" above is not clear to me.

Oleg.

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