linux-kernel - Re: Patch related with Fork Bombing Atack

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Date:	Fri, 1 Jun 2007 09:30:20 +0200
From:	Jens Axboe <jens.axboe@...cle.com>
To:	Daniel Hazelton <dhazelton@...er.net>
Cc:	Anand Jahagirdar <anandjigar@...il.com>, security@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: Patch related with Fork Bombing Atack

On Fri, Jun 01 2007, Daniel Hazelton wrote:
> On Friday 01 June 2007 02:48:59 Anand Jahagirdar wrote:
> > On 5/31/07, Jens Axboe <jens.axboe@...cle.com> wrote:
> > > On Thu, May 31 2007, Anand Jahagirdar wrote:
> > > > 2) Printk message in my patch will definitely help Administrator/Root
> > > > User to detect which particular user is trying fork bombing attack on
> > > > his machine by looking at /var/log/messages or dmesg . he can take
> > > > action against that particular user and kill his processes.
> > >
> > > You just opened a DoS possibility for any user, they can now flood the
> > > syslog instead.
> >
> > Jens Axboe
> >
> >      when they try to flood the syslog using fork bombing attack,
> > their messge will be printed only once in syslog and it will show how
> > many times it has repeated. due to this he will not able to flood the
> > syslog.and i am using only one single variable in my printk messge so
> > it is quite not possible to flood the syslog.
> >
> >    am i missing something??
> >
> > anand
> 
> Most definately. Each printk() call outputs to syslog - which means
> that every time your code outputs its message there is another line in
> the logs. It then becomes possible to use that to flood the syslog.

I think Anand is assuming that because syslog may coalesce identical
messages into "repeated foo times" in the messages file, that it's not a
dos. That is of course wrong.

-- 
Jens Axboe

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