Date: Fri, 23 Nov 2007 08:34:47 +0100
From: Radoslaw Szkodzinski (AstralStorm) <lkml@astralstorm.puszkin.org>
To: Dane Mutters <dmutters@gmail.com>
Cc: Diego Calleja <diegocg@gmail.com>, Martin Olsson <mnemo@minimum.se>,
       Peter Zijlstra <peterz@infradead.org>,
       Alan Cox <alan@lxorguk.ukuu.org.uk>, linux-kernel@vger.kernel.org
Subject: Re: Is it possible to give the user the option to cancel forkbombs?
Message-ID: <20071123083447.3a3e4d23@astralstorm.puszkin.org>
In-Reply-To: <1195322101.15120.3.camel@Orchestrator>
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	<1195285481.3059.12.camel@twins>
	<473F281B.60408@minimum.se>
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On Sat, 17 Nov 2007 09:55:01 -0800
Dane Mutters <dmutters@gmail.com> wrote:

> I don't know if this is at all feasible, but is it possible to have a
> mechanism that would detect a fork bomb in progress and either stop the
> fork, or allow the user to cancel the operation?  For example, are there
> any legitimate processes (i.e. ones that really need to fork like crazy)
> that would need to generate 200+ processes in less than 1 second?
>=20
> (Note: I'm not a programmer; I'm just throwing out the idea.)
>=20

If the parent PID of the new task is exported through TASKSTATS, you can
do it already in userspace. If not, that data should be exported.

Then you could write a root daemon using netlink, set it to RT priority
and create an inheritable counter in it to thwart binary forking.
The counter would be cleared every x seconds.
No need to do it in the kernel.

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