kernel-hardening - Re: [RFC] ipc: introduce shm_rmid

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Message-ID: <20110701112534.GG20990@elte.hu>
Date: Fri, 1 Jul 2011 13:25:34 +0200
From: Ingo Molnar <mingo@...e.hu>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Vasiliy Kulikov <segoon@...nwall.com>,
	kernel-hardening@...ts.openwall.com,
	Randy Dunlap <rdunlap@...otime.net>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	"Serge E. Hallyn" <serge.hallyn@...onical.com>,
	Daniel Lezcano <daniel.lezcano@...e.fr>,
	Oleg Nesterov <oleg@...hat.com>, Tejun Heo <tj@...nel.org>,
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org
Subject: Re: [RFC] ipc: introduce shm_rmid_forced sysctl


* Andrew Morton <akpm@...ux-foundation.org> wrote:

> > --- a/ipc/shm.c
> > +++ b/ipc/shm.c
> > @@ -74,6 +74,7 @@ void shm_init_ns(struct ipc_namespace *ns)
> >  	ns->shm_ctlmax = SHMMAX;
> >  	ns->shm_ctlall = SHMALL;
> >  	ns->shm_ctlmni = SHMMNI;
> > +	ns->shm_rmid_forced = 0;
> >  	ns->shm_tot = 0;
> >  	ipc_init_ids(&shm_ids(ns));
> >  }
> 
> The problem is that nobody will test your feature.  So for testing
> purposes, let's enable the feature by default.  I assume this:

I'd also strongly argue to keep this as a default. OOM-kills are not 
part of POSIX and violate POSIX in a number of ways already.

Furthermore, if testing shows that this is not actually breaking 
anything in a serious way we could also in theory simplify the patch 
and just make this the default behavior with no runtime ability to 
switch it off.

Thanks,

	Ingo

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