netdev - Re: [kernel-hardening] Re: [PATCH v7 3/6] random: use SipHash in place of MD5

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Message-ID: <CAHmME9o6Qt5aLrP68p-6yPrLz9+DP_kictsXa5GbKz0Bfa3o7Q@mail.gmail.com>
Date:   Thu, 22 Dec 2016 17:36:47 +0100
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     kernel-hardening@...ts.openwall.com,
        "Theodore Ts'o" <tytso@....edu>,
        "Jason A. Donenfeld" <Jason@...c4.com>,
        Hannes Frederic Sowa <hannes@...essinduktion.org>,
        Andy Lutomirski <luto@...capital.net>,
        Netdev <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux Crypto Mailing List <linux-crypto@...r.kernel.org>,
        David Laight <David.Laight@...lab.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Eric Biggers <ebiggers3@...il.com>,
        Tom Herbert <tom@...bertland.com>,
        Andi Kleen <ak@...ux.intel.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jean-Philippe Aumasson <jeanphilippe.aumasson@...il.com>
Subject: Re: [kernel-hardening] Re: [PATCH v7 3/6] random: use SipHash in
 place of MD5

On Thu, Dec 22, 2016 at 5:30 PM, Theodore Ts'o <tytso@....edu> wrote:
> I'd do this first, as one set.  Adding a new file to crypto is
> unlikely to cause merge conflicts.

Ack.

>
>> 2. convert char/random to use siphash. to: ted ts'o's random-next
>
> I'm confused, I thought you had agreed to the batched chacha20
> approach?

Sorry, I meant to write this. Long day, little sleep. Yes, of course.
Batched entropy.

>> 3. move lib/md5.c to static function in crypto/md5.c, remove entry
>> inside of linux/cryptohash.h. to: ??'s ??-next
>
> This is cleanup, so it doesn't matter that much when it happens.  md5
> changes to crypto is also unlikely to cause conflicts, so we could do
> this at the same time as (2), if Herbert (the crypto maintainer) agrees.

Alright, sure.

>
>> 4. move lib/halfmd4.c to static function in fs/ext/hash.c, remove
>> entry inside of linux/cryptohash.c. to: td ts'o's ext-next
>
> This is definitely separate.

Okay, I'll submit it to you separately.

> One more thing.  Can you add some test cases to lib/siphash.h?
> Triggered off of a CONFIG_SIPHASH_REGRESSION_TEST config flag, with
> some test inputs and known outputs?  I'm going to need to add a
> version of siphash to e2fsprogs, and I want to make sure the userspace
> version is implementing the same algorithm as the kernel siphash.

I've already written these. They're behind TEST_HASH. They currently
test every single line of code of all implementations of siphash. I
spent a long time on these. The test vectors themselves were taken
from the SipHash creators' reference publication. Check out
lib/test_siphash.c in my tree.

Jason

On Thu, Dec 22, 2016 at 5:30 PM, Theodore Ts'o <tytso@....edu> wrote:
> On Thu, Dec 22, 2016 at 05:16:47PM +0100, Jason A. Donenfeld wrote:
>> Could you offer a bit of advice on how to manage dependencies between
>> patchsets during merge windows? I'm a bit new to the process.
>>
>> Specifically, we how have 4 parts:
>> 1. add siphash, and use it for some networking code. to: david miller's net-next
>
> I'd do this first, as one set.  Adding a new file to crypto is
> unlikely to cause merge conflicts.
>
>> 2. convert char/random to use siphash. to: ted ts'o's random-next
>
> I'm confused, I thought you had agreed to the batched chacha20
> approach?
>
>> 3. move lib/md5.c to static function in crypto/md5.c, remove entry
>> inside of linux/cryptohash.h. to: ??'s ??-next
>
> This is cleanup, so it doesn't matter that much when it happens.  md5
> changes to crypto is also unlikely to cause conflicts, so we could do
> this at the same time as (2), if Herbert (the crypto maintainer) agrees.
>
>> 4. move lib/halfmd4.c to static function in fs/ext/hash.c, remove
>> entry inside of linux/cryptohash.c. to: td ts'o's ext-next
>
> This is definitely separate.
>
> One more thing.  Can you add some test cases to lib/siphash.h?
> Triggered off of a CONFIG_SIPHASH_REGRESSION_TEST config flag, with
> some test inputs and known outputs?  I'm going to need to add a
> version of siphash to e2fsprogs, and I want to make sure the userspace
> version is implementing the same algorithm as the kernel siphash.
>
>                                               - Ted



-- 
Jason A. Donenfeld
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