linux-kernel - RE: [PATCH] Make core_pattern support namespace

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Message-ID: <009601d16a43$de01fb80$9a05f280$@cn.fujitsu.com>
Date:	Thu, 18 Feb 2016 19:59:48 +0800
From:	Zhao Lei <zhaolei@...fujitsu.com>
To:	'Mateusz Guzik' <mguzik@...hat.com>,
	"'Eric W. Biederman'" <ebiederm@...ssion.com>
CC:	<containers@...ts.linux-foundation.org>,
	<linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] Make core_pattern support namespace

Hi, Mateusz Guzik

> -----Original Message-----
> From: Mateusz Guzik [mailto:mguzik@...hat.com]
> Sent: Thursday, February 18, 2016 4:54 AM
> To: Eric W. Biederman <ebiederm@...ssion.com>
> Cc: Zhao Lei <zhaolei@...fujitsu.com>; containers@...ts.linux-foundation.org;
> linux-kernel@...r.kernel.org
> Subject: Re: [PATCH] Make core_pattern support namespace
> 
> On Wed, Feb 17, 2016 at 02:15:24PM -0600, Eric W. Biederman wrote:
> > Mateusz Guzik <mguzik@...hat.com> writes:
> > > On Tue, Feb 16, 2016 at 07:33:39PM +0800, Zhao Lei wrote:
> > >> For container based on namespace design, it is good to allow
> > >> each container keeping their own coredump setting.
> > >
> > > Sorry if this is a false alarm, I don't have easy means to test it, but
> > > is not this an immediate privilege escalation?
> >
> > It is.  This is why we do not currently have a per namespace setting.
> >
> 
> Thanks for confimation.
> 
> > Solving the user mode helper problem is technically a fair amount of
> > work, if not theoretically challenging.
> >
> 
> Well, I would say custom core_patterns without pipe support are still
> better than none.
> 
+1.

> Say one would ensure a stable core_pattern (i.e. that it cannot be
> modified as it is being parsed) and a restricted set of allowed
> characters in the pattern (which would not include the pipe), validated
> when one attempts to set the pattern.
> 
> Does this sound acceptable? If so, and there are no counter ideas from
> Lei, I can get around to that.
> 
If we can let kernel select pipe_program in vm's filesystem, and run
pipe_program with vm's filesystem, set a pipe for core_patterm in vm
will be safe.
What is your opinion on above solution?

If above way is not acceptable, or impossible to realize, I also
agree your solution of limit vm setting pipe.

Thanks
Zhaolei

> --
> Mateusz Guzik