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

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Message-ID: <20161222163041.xb2ysx4uswpaqfev@thunk.org>
Date:   Thu, 22 Dec 2016 11:30:41 -0500
From:   Theodore Ts'o <tytso@....edu>
To:     kernel-hardening@...ts.openwall.com
Cc:     "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 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