From: David Laight <David.Laight@ACULAB.COM>
To: "'Jason A. Donenfeld'" <Jason@zx2c4.com>,
Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: Netdev <netdev@vger.kernel.org>,
"kernel-hardening@lists.openwall.com"
<kernel-hardening@lists.openwall.com>,
Andi Kleen <ak@linux.intel.com>,
LKML <linux-kernel@vger.kernel.org>,
Linux Crypto Mailing List <linux-crypto@vger.kernel.org>
Subject: RE: [PATCH v2 3/4] secure_seq: use siphash24 instead of md5_transform
Date: Wed, 14 Dec 2016 14:47:11 +0000 [thread overview]
Message-ID: <063D6719AE5E284EB5DD2968C1650D6DB023F7BD@AcuExch.aculab.com> (raw)
In-Reply-To: <CAHmME9o4NVi-MPeURio1Ga58rnW6JAGQdTg6scd+K3EZEf3RNA@mail.gmail.com>
From: Jason A. Donenfeld
> Sent: 14 December 2016 13:44
> To: Hannes Frederic Sowa
> > __packed not only removes all padding of the struct but also changes the
> > alignment assumptions for the whole struct itself. The rule, the struct
> > is aligned by its maximum alignment of a member is no longer true. That
> > said, the code accessing this struct will change (not on archs that can
> > deal efficiently with unaligned access, but on others).
>
> That's interesting. There currently aren't any alignment requirements
> in siphash because we use the unaligned helper functions, but as David
> pointed out in another thread, maybe that too should change. In that
> case, we'd have an aligned-only version of the function that requires
> 8-byte aligned input. Perhaps the best way to go about that would be
> to just mark the struct as __packed __aligned(8). Or, I guess, since
> 64-bit accesses gets split into two on 32-bit, that'd be best descried
> as __packed __aligned(sizeof(long)). Would that be an acceptable
> solution?
Just remove the __packed and ensure that the structure is 'nice'.
This includes ensuring there is no 'tail padding'.
In some cases you'll need to put the port number into a 32bit field.
I'd also require that the key be aligned.
It probably ought to be a named structure type with two 64bit members
(or with an array member that has two elements).
David
next prev parent reply other threads:[~2016-12-14 14:47 UTC|newest]
Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-14 3:59 [PATCH v2 1/4] siphash: add cryptographically secure hashtable function Jason A. Donenfeld
2016-12-14 3:59 ` [PATCH v2 2/4] siphash: add convenience functions for jhash converts Jason A. Donenfeld
2016-12-14 3:59 ` [PATCH v2 3/4] secure_seq: use siphash24 instead of md5_transform Jason A. Donenfeld
2016-12-14 12:53 ` Jason A. Donenfeld
2016-12-14 13:16 ` Hannes Frederic Sowa
2016-12-14 13:44 ` Jason A. Donenfeld
2016-12-14 14:47 ` David Laight [this message]
2016-12-14 17:49 ` Jason A. Donenfeld
2016-12-14 17:56 ` David Miller
2016-12-14 18:06 ` Jason A. Donenfeld
2016-12-14 19:22 ` Hannes Frederic Sowa
2016-12-14 19:38 ` Jason A. Donenfeld
2016-12-14 20:27 ` Hannes Frederic Sowa
2016-12-14 20:12 ` Tom Herbert
2016-12-14 21:01 ` Jason A. Donenfeld
2016-12-14 3:59 ` [PATCH v2 4/4] random: use siphash24 instead of md5 for get_random_int/long Jason A. Donenfeld
2016-12-14 11:21 ` [PATCH v2 1/4] siphash: add cryptographically secure hashtable function Hannes Frederic Sowa
2016-12-14 13:10 ` Jason A. Donenfeld
2016-12-14 15:09 ` Hannes Frederic Sowa
2016-12-14 19:47 ` Jason A. Donenfeld
2016-12-15 7:57 ` Herbert Xu
2016-12-15 8:15 ` [kernel-hardening] " Daniel Micay
2016-12-14 12:46 ` Jason A. Donenfeld
2016-12-14 22:03 ` Hannes Frederic Sowa
2016-12-14 23:29 ` Jason A. Donenfeld
2016-12-15 8:31 ` Hannes Frederic Sowa
2016-12-15 11:04 ` David Laight
2016-12-15 12:23 ` Hannes Frederic Sowa
2016-12-15 12:28 ` David Laight
2016-12-15 12:50 ` Hannes Frederic Sowa
2016-12-15 13:56 ` David Laight
2016-12-15 14:56 ` Hannes Frederic Sowa
2016-12-15 15:41 ` David Laight
2016-12-15 15:53 ` Hannes Frederic Sowa
2016-12-15 18:50 ` Jason A. Donenfeld
2016-12-15 20:31 ` Hannes Frederic Sowa
2016-12-15 20:43 ` Jason A. Donenfeld
2016-12-15 21:04 ` Peter Zijlstra
2016-12-15 21:09 ` Hannes Frederic Sowa
2016-12-15 21:17 ` Hannes Frederic Sowa
2016-12-15 21:09 ` Peter Zijlstra
2016-12-15 21:11 ` [kernel-hardening] " Jason A. Donenfeld
2016-12-15 21:14 ` Linus Torvalds
2016-12-14 18:46 ` [PATCH v3 1/3] " Jason A. Donenfeld
2016-12-14 18:46 ` [PATCH v3 2/3] secure_seq: use siphash24 instead of md5_transform Jason A. Donenfeld
2016-12-14 21:44 ` kbuild test robot
2016-12-14 18:46 ` [PATCH v3 3/3] random: use siphash24 instead of md5 for get_random_int/long Jason A. Donenfeld
2016-12-14 21:56 ` kbuild test robot
2016-12-14 21:57 ` kbuild test robot
2016-12-15 10:14 ` David Laight
2016-12-15 18:51 ` Jason A. Donenfeld
2016-12-14 19:18 ` [PATCH v3 1/3] siphash: add cryptographically secure hashtable function Tom Herbert
2016-12-14 19:35 ` Jason A. Donenfeld
2016-12-14 20:55 ` Jason A. Donenfeld
2016-12-14 21:35 ` Tom Herbert
2016-12-14 22:56 ` Jason A. Donenfeld
2016-12-14 23:14 ` Tom Herbert
2016-12-14 23:17 ` Jason A. Donenfeld
2016-12-18 0:06 ` Christian Kujau
2016-12-14 23:30 ` Linus Torvalds
2016-12-14 23:34 ` Jason A. Donenfeld
2016-12-15 0:10 ` Linus Torvalds
2016-12-15 10:22 ` David Laight
2016-12-14 21:15 ` kbuild test robot
2016-12-14 21:21 ` Jason A. Donenfeld
2016-12-15 1:46 ` [PATCH v4 1/4] " Jason A. Donenfeld
2016-12-15 1:46 ` [PATCH v4 2/4] siphash: add N[qd]word helpers Jason A. Donenfeld
2016-12-15 1:46 ` [PATCH v4 3/4] secure_seq: use siphash instead of md5_transform Jason A. Donenfeld
2016-12-15 1:46 ` [PATCH v4 4/4] random: use siphash instead of MD5 for get_random_int/long Jason A. Donenfeld
2016-12-15 4:23 ` [PATCH v4 1/4] siphash: add cryptographically secure hashtable function kbuild test robot
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