Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1542153

Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable function

From "Jason A. Donenfeld" <Jason@zx2c4.com>
Newsgroups linux.kernel
Subject Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable function
Date 2016-12-14 20:50 +0100
Message-ID <sOnIR-2Wp-7@gated-at.bofh.it> (permalink)
References <sO93b-1Im-3@gated-at.bofh.it> <sOg4F-5SB-1@gated-at.bofh.it> <sOhDs-6UF-13@gated-at.bofh.it> <sOjvA-82q-25@gated-at.bofh.it>
Organization linux.* mail to news gateway

Show all headers | View raw

Hi Hannes,

On Wed, Dec 14, 2016 at 4:09 PM, Hannes Frederic Sowa
<hannes@stressinduktion.org> wrote:
> Yes, numbers would be very usable here. I am mostly concerned about
> small plastic router cases. E.g. assume you double packet processing
> time with a change of the hashing function at what point is the actual
> packet processing more of an attack vector than the hashtable?

I agree. Looks like Tom did some very quick benchmarks. I'll do some
more precise benchmarks myself when we graduate from looking at md5
replacement (the easy case) to looking at jhash replacement (the
harder case).

>> With that said, siphash is here to replace uses of jhash where
>> hashtable poisoning vulnerabilities make it necessary. Where there's
>> no significant security improvement, if there's no speed improvement
>> either, then of course nothing's going to change.
>
> It still changes currently well working source. ;-)

I mean if siphash doesn't make things better in someway, we'll just
continue using jhash, so no source change or anything. In other words:
evolutionary conservative approach rather than hasty "replace 'em
all!" tomfoolery.

> MD5 is considered broken because its collision resistance is broken?
> SipHash doesn't even claim to have collision resistance (which we don't
> need here)?

Not just that, but it's not immediately clear to me that using MD5 as
a PRF the way it is now with md5_transform is even a straightforwardly
good idea.

> But I agree, certainly it could be a nice speed-up!

The benchmarks for the secure sequence number generation and the rng
are indeed really promising.

> I think you mean non-linearity.

Yea of course, editing typo, sorry.

> In general I am in favor to switch to siphash, but it would be nice to
> see some benchmarks with the specific kernel implementation also on some
> smaller 32 bit CPUs and especially without using any SIMD instructions
> (which might have been used in paper comparison).

Sure, agreed. Each proposed jhash replacement will need to be
benchmarked on little MIPS machines and x86 monsters alike, with
patches indicating PPS before and after.

Jason

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH v2 1/4] siphash: add cryptographically secure hashtable function "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-14 05:10 +0100
  Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function Hannes Frederic Sowa <hannes@stressinduktion.org> - 2016-12-14 12:40 +0100
    Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable function "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-14 14:20 +0100
      Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function Hannes Frederic Sowa <hannes@stressinduktion.org> - 2016-12-14 16:20 +0100
        Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable function "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-14 20:50 +0100
      Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function Herbert Xu <herbert@gondor.apana.org.au> - 2016-12-15 09:00 +0100
        Re: [kernel-hardening] Re: [PATCH v2 1/4] siphash: add  cryptographically secure hashtable function Daniel Micay <danielmicay@gmail.com> - 2016-12-15 09:20 +0100
  Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable function "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-14 13:50 +0100
    Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function Hannes Frederic Sowa <hannes@stressinduktion.org> - 2016-12-14 23:10 +0100
      Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable function "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-15 00:40 +0100
        Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function Hannes Frederic Sowa <hannes@stressinduktion.org> - 2016-12-15 09:40 +0100
      RE: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function David Laight <David.Laight@ACULAB.COM> - 2016-12-15 12:10 +0100
        RE: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function David Laight <David.Laight@ACULAB.COM> - 2016-12-15 13:30 +0100
          Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function Hannes Frederic Sowa <hannes@stressinduktion.org> - 2016-12-15 14:00 +0100
            RE: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function David Laight <David.Laight@ACULAB.COM> - 2016-12-15 15:00 +0100
              Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function Hannes Frederic Sowa <hannes@stressinduktion.org> - 2016-12-15 16:00 +0100
                RE: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function David Laight <David.Laight@ACULAB.COM> - 2016-12-15 16:50 +0100
                Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function Hannes Frederic Sowa <hannes@stressinduktion.org> - 2016-12-15 17:00 +0100
                Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable function "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-15 20:00 +0100
                Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function Hannes Frederic Sowa <hannes@stressinduktion.org> - 2016-12-15 21:40 +0100
                Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable function "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-15 21:50 +0100
                Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function Hannes Frederic Sowa <hannes@stressinduktion.org> - 2016-12-15 22:20 +0100
                Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function Hannes Frederic Sowa <hannes@stressinduktion.org> - 2016-12-15 22:20 +0100
                Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function Peter Zijlstra <peterz@infradead.org> - 2016-12-15 23:10 +0100
                Re: [kernel-hardening] Re: [PATCH v2 1/4] siphash: add  cryptographically secure hashtable function "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-15 22:20 +0100
                Re: [kernel-hardening] Re: [PATCH v2 1/4] siphash: add  cryptographically secure hashtable function Linus Torvalds <torvalds@linux-foundation.org> - 2016-12-15 22:20 +0100
                Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function Peter Zijlstra <peterz@infradead.org> - 2016-12-15 22:20 +0100
        Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function Hannes Frederic Sowa <hannes@stressinduktion.org> - 2016-12-15 13:30 +0100
  [PATCH v3 2/3] secure_seq: use siphash24 instead of md5_transform "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-14 19:50 +0100
    Re: [PATCH v3 2/3] secure_seq: use siphash24 instead of md5_transform kbuild test robot <lkp@intel.com> - 2016-12-14 22:50 +0100
  [PATCH v3 1/3] siphash: add cryptographically secure hashtable function "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-14 19:50 +0100
    [PATCH v3 3/3] random: use siphash24 instead of md5 for get_random_int/long "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-14 19:50 +0100
      Re: [PATCH v3 3/3] random: use siphash24 instead of md5 for  get_random_int/long kbuild test robot <lkp@intel.com> - 2016-12-14 23:00 +0100
      Re: [PATCH v3 3/3] random: use siphash24 instead of md5 for  get_random_int/long kbuild test robot <lkp@intel.com> - 2016-12-14 23:10 +0100
      RE: [PATCH v3 3/3] random: use siphash24 instead of md5 for  get_random_int/long David Laight <David.Laight@ACULAB.COM> - 2016-12-15 11:20 +0100
        Re: [PATCH v3 3/3] random: use siphash24 instead of md5 for get_random_int/long "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-15 20:00 +0100
    Re: [PATCH v3 1/3] siphash: add cryptographically secure hashtable function Tom Herbert <tom@herbertland.com> - 2016-12-14 20:20 +0100
      Re: [PATCH v3 1/3] siphash: add cryptographically secure hashtable function "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-14 20:40 +0100
        Re: [PATCH v3 1/3] siphash: add cryptographically secure hashtable function "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-14 22:00 +0100
          Re: [PATCH v3 1/3] siphash: add cryptographically secure hashtable function Tom Herbert <tom@herbertland.com> - 2016-12-14 22:40 +0100
            Re: [PATCH v3 1/3] siphash: add cryptographically secure hashtable function "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-15 00:00 +0100
              Re: [PATCH v3 1/3] siphash: add cryptographically secure hashtable function "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-15 00:20 +0100
                Re: [PATCH v3 1/3] siphash: add cryptographically secure hashtable  function Christian Kujau <lists@nerdbynature.de> - 2016-12-18 01:10 +0100
              Re: [PATCH v3 1/3] siphash: add cryptographically secure hashtable function Tom Herbert <tom@herbertland.com> - 2016-12-15 00:20 +0100
              Re: [PATCH v3 1/3] siphash: add cryptographically secure hashtable function "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-15 00:40 +0100
                Re: [PATCH v3 1/3] siphash: add cryptographically secure hashtable function Linus Torvalds <torvalds@linux-foundation.org> - 2016-12-15 01:30 +0100
                RE: [PATCH v3 1/3] siphash: add cryptographically secure hashtable  function David Laight <David.Laight@ACULAB.COM> - 2016-12-15 11:30 +0100
              Re: [PATCH v3 1/3] siphash: add cryptographically secure hashtable function Linus Torvalds <torvalds@linux-foundation.org> - 2016-12-15 00:40 +0100
    Re: [PATCH v3 1/3] siphash: add cryptographically secure hashtable  function kbuild test robot <lkp@intel.com> - 2016-12-14 22:20 +0100
      Re: [PATCH v3 1/3] siphash: add cryptographically secure hashtable function "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-14 22:30 +0100
    [PATCH v4 3/4] secure_seq: use siphash instead of md5_transform "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-15 02:50 +0100
    [PATCH v4 2/4] siphash: add N[qd]word helpers "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-15 02:50 +0100
    [PATCH v4 4/4] random: use siphash instead of MD5 for get_random_int/long "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-15 02:50 +0100
    [PATCH v4 1/4] siphash: add cryptographically secure hashtable function "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-15 02:50 +0100

csiph-web