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From: Thomas Graf <tgraf@suug.ch>
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Daniel Borkmann <dborkman@redhat.com>,
	"David S. Miller" <davem@davemloft.net>,
	Theodore Ts'o <tytso@mit.edu>,
	netdev@vger.kernel.org,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: Where exactly will arch_fast_hash be used
Date: Thu, 4 Dec 2014 15:39:38 +0000	[thread overview]
Message-ID: <20141204153938.GC32140@casper.infradead.org> (raw)
In-Reply-To: <20141204152929.GA22075@gondor.apana.org.au>

On 12/04/14 at 11:29pm, Herbert Xu wrote:
> On Thu, Dec 04, 2014 at 03:26:37PM +0000, Thomas Graf wrote:
> >
> > As Daniel pointed out, this work originated for the OVS edge use
> > case where security is of less concern and the rehashing is
> > sufficient. Identifying collisions is less of interest as the user
> > space fall back provides a greater surface for an attack.
> 
> Well in that case the current setup I think is very misleading.
> It's inviting unsuspecting kernel developers to use it as a hash
> function for general hash tables, which AFAICS is something that
> it fails at miserably.

Well, it's called fast hash and not secure hash ;-) but a clear hint
definitely wouldn't hurt.

I wasn't aware of the distribution weakness of the lower bits. Do
you have a reference to more information?

  reply	other threads:[~2014-12-04 15:39 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-12-04  8:11 Where exactly will arch_fast_hash be used Herbert Xu
2014-12-04 12:34 ` Hannes Frederic Sowa
2014-12-04 13:14   ` Daniel Borkmann
2014-12-04 15:26 ` Thomas Graf
2014-12-04 15:29   ` Herbert Xu
2014-12-04 15:39     ` Thomas Graf [this message]
2014-12-04 15:43       ` Daniel Borkmann
2014-12-04 15:47         ` Herbert Xu
2014-12-04 15:51           ` Daniel Borkmann
2014-12-04 15:56           ` David Laight
2014-12-04 16:10             ` Herbert Xu
  -- strict thread matches above, loose matches on Subject: below --
2014-12-07  5:20 George Spelvin
2014-12-07  9:28 ` Herbert Xu
2014-12-07 10:02   ` George Spelvin
2014-12-07 12:51     ` Herbert Xu
2014-12-07 13:23       ` George Spelvin
2014-12-07 14:06         ` Hannes Frederic Sowa
2014-12-07 21:33           ` George Spelvin
2014-12-08 11:25             ` Hannes Frederic Sowa
2014-12-08 16:19               ` George Spelvin
2014-12-08 16:32                 ` Hannes Frederic Sowa
2014-12-09 14:24         ` Herbert Xu
2014-12-07 13:14 ` Hannes Frederic Sowa
2014-12-07 13:30   ` George Spelvin
2014-12-07 13:41     ` Hannes Frederic Sowa
2014-12-07 13:52       ` Hannes Frederic Sowa

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