linux-kernel - Re: Where is RLIMIT_RT

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Date:	Sat, 15 Jul 2006 16:42:57 +0200
From:	Arjan van de Ven <arjan@...radead.org>
To:	Jean-Marc Valin <Jean-Marc.Valin@...erbrooke.ca>
Cc:	Lee Revell <rlrevell@...-job.com>,
	Esben Nielsen <nielsen.esben@...glemail.com>,
	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>
Subject: Re: Where is RLIMIT_RT_CPU?

On Sun, 2006-07-16 at 00:19 +1000, Jean-Marc Valin wrote:
> > Non-root RT tasks are not "unprivileged" - they have a level of
> > privileges between a normal user and root.  Really I think it's OK for
> > these tasks to consume 100% CPU, as the admin has explicitly allowed it.
> 
> Sure, if the admin has allowed it, but I think it's also OK for desktop
> users to have access to rt scheduling by default, as long as their tasks
> are "well-behaved" (i.e. only use a few percent CPU).
> 
> > The only problem is that Ubuntu shipped with this enabled for everyone.
> 
> The problem is not the fact that it's enabled, but the fact that the
> amount of CPU allowed isn't restricted.

as long as you can fork and exec as many of those processes as you want
a per process rlimit is useless security wise... an evil user just fires
off a second process just before the first one gets killed and a non-RT
root still is starved out.


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