Subject: Re: TALPA - a threat model?  well sorta.
From: Peter Zijlstra <peterz@infradead.org>
To: Helge Hafting <helge.hafting@aitel.hist.no>
Cc: Eric Paris <eparis@redhat.com>, Arjan van de Ven <arjan@infradead.org>,
       linux-kernel@vger.kernel.org, malware-list@lists.printk.net,
       andi@firstfloor.org, riel@redhat.com, greg@kroah.com, tytso@mit.edu,
       viro@ZenIV.linux.org.uk, alan@lxorguk.ukuu.org.uk, hch@infradead.org
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Date: Fri, 15 Aug 2008 12:37:25 +0200
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On Fri, 2008-08-15 at 12:07 +0200, Helge Hafting wrote:
> It seems to me that this "scan on file open" business is the
> wrong way to do things - because it reduces performance.
> 
> If you scan on file open, then your security sw is too late and
> getting in the way.
> 
> It is better to scan in advance. Most machines has lots of idle time.
> Use that time to scan in advance, and mark the files as "clean".
> 
> A "clean" file can be opened without further checking anytime - giving
> normal high performance.  A file that gets written to becomes "dirty"
> until checked again. Some mechanism for making a clean copy of a
> clean file might help avoid excessive "dirtying".
> 
> "Scan on open" might still be useful for cases when the system
> haven't kept up with writing, but please don't aim to have
> this be the _primary_ mode of scanning. A file server
> where most of the stuff is pre-scanned will likely perform much better
> than  one scanning everything on open.

This is the source of all that scan on write/close rambling I've seen go
past the last couple of days..

So I'd not worry about this particular aspect

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