Re: [PATCH 5/5] pid: use namespaced iteration on processes while managing priority

[Matt Helsley <matthltc-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>]

On Thu, 2008-12-18 at 10:54 -0800, Eric W. Biederman wrote:
> "Serge E. Hallyn" <serue-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org> writes:
> 
> 
> > The uid check needs to be fixed for user namespaces, agreed.  I could
> > go either way though on whether we should also restrict to the same
> > pidns.
> 
> It would be a subtle unexpected semantic change, that we would need
> to copy linux-abi and document etc.  I'm not convinced it is that
> useful.
> 
> I'm inclined to keep the semantics pure until there is some real
> experience from the field on issues like this.

Well the man page talks about PRIO_PROCESS and PRIO_PGRP and in those
cases it looks like "who" is really a pid or pgrp id:

>        The  value  which  is one of PRIO_PROCESS, PRIO_PGRP, or PRIO_USER, and
>        who  is  interpreted  relative  to  which  (a  process  identifier  for
>        PRIO_PROCESS, process group identifier for PRIO_PGRP, and a user ID for
>        PRIO_USER). 

It looks to me like restricting by pidns is required if "which" is
PRIO_PROCESS or PRIO_PGRP. If "which" is PRIO_USER then yes, it sounds
like a user ns issue.

Cheers,
	-Matt Helsley