linux-kernel - Re: Versioning file system

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Date:	Thu, 5 Jul 2007 19:57:35 +0200
From:	Erik Mouw <mouw@...linux.org>
To:	John Stoffel <john@...ffel.org>
Cc:	Theodore Tso <tytso@....edu>, alan <alan@...eserver.org>,
	J?rn Engel <joern@...fs.org>, "H. Peter Anvin" <hpa@...or.com>,
	Jack Stone <jack@...keye.stone.uk.eu.org>,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	akpm@...ux-foundation.org, viro@...iv.linux.org.uk
Subject: Re: Versioning file system

On Thu, Jul 05, 2007 at 09:57:40AM -0400, John Stoffel wrote:
> >>>>> "Erik" == Erik Mouw <mouw@...linux.org> writes:
> Erik> The only valid use of Streams in Windows I've seen was a virus
> Erik> checker that stored a hash of the file in a separate
> Erik> stream. Checking a file was a matter of rehashing it and
> Erik> comparing against the hash stored in the special hash data
> Erik> stream for that particular file.
> 
> So what was stopping a virus from infecting a file, re-computing the
> hash and pushing the new hash into the stream?  

Nothing, but the same holds for virus checkers that store the hash in a
separate file. The only advantage of storing the hash in a stream is
that the stream is automatically deleted when you remove the file.

> You need to keep the computed hashes on Read-Only media for true
> security, once you let the system change them, then you're toast....

Agreed.


Erik

-- 
They're all fools. Don't worry. Darwin may be slow, but he'll
eventually get them. -- Matthew Lammers in alt.sysadmin.recovery

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