linux-kernel - Re: [malware-list] scanner interface proposal was: [TALPA] Intro to a linux interface for on access scanning

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Message-Id: <20080818153212.6A6FD33687F@pmx1.sophos.com>
Date:	Mon, 18 Aug 2008 16:31:09 +0100
From:	tvrtko.ursulin@...hos.com
To:	Theodore Tso <tytso@....edu>
Cc:	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Arjan van de Ven <arjan@...radead.org>,
	Adrian Bunk <bunk@...nel.org>, capibara@...all.nl,
	Casey Schaufler <casey@...aufler-ca.com>, davecb@....com,
	david@...g.hm, linux-kernel <linux-kernel@...r.kernel.org>,
	linux-security-module@...r.kernel.org,
	malware-list@...ts.printk.net,
	malware-list-bounces@...sg.printk.net,
	Mihai Don??u <mdontu@...defender.com>,
	Peter Dolding <oiaohm@...il.com>, Pavel Machek <pavel@...e.cz>,
	rmeijer@...all.nl
Subject: Re: [malware-list] scanner interface proposal was: [TALPA] Intro	to a linux
 interface for on access scanning

Theodore Tso <tytso@....edu> wrote on 18/08/2008 15:25:11:

> On Mon, Aug 18, 2008 at 02:15:24PM +0100, tvrtko.ursulin@...hos.com 
wrote:
> > Then there is still a question of who allows some binary to declare 
itself 
> > exempt. If that decision was a mistake, or it gets compromised 
security 
> > will be off. A very powerful mechanism which must not be easily 
> > accessible.  With a good cache your worries go away even without a 
scheme 
> > like this.
> 
> I have one word for you --- bittorrent.  If you are downloading a very
> large torrent (say approximately a gigabyte), and it contains many
> pdf's that are say a few megabytes a piece, and things are coming in
> tribbles, having either a indexing scanner or an AV scanner wake up
> and rescan the file from scratch each time a tiny piece of the pdf
> comes in is going to eat your machine alive....

Huh? I was never advocating re-scan after each modification and I even 
explicitly said it does not make sense for AV not only for performance but 
because it will be useless most of the time. I thought sending out 
modified notification on close makes sense because it is a natural point, 
unless someone is trying to subvert which is out of scope. Other have 
suggested time delay and lumping up.

Also, just to double-check, you don't think AV scanning would read the 
whole file on every write?

--
Tvrtko A. Ursulin
Senior Software Engineer, Sophos

"Views and opinions expressed in this email are strictly those of the 
author.
 The contents has not been reviewed or approved by Sophos."
 

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