From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Subject: Re: [kernel-hardening] Re: [PATCH v7 3/6] random: use SipHash in
 place of MD5
Date: Thu, 22 Dec 2016 16:41:59 +0100
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Cc: kernel-hardening@lists.openwall.com,
        "Theodore Ts'o" <tytso@mit.edu>,
        Andy Lutomirski <luto@amacapital.net>,
        Netdev <netdev@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
        David Laight <David.Laight@aculab.com>,
        Eric Dumazet <edumazet@google.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Eric Biggers <ebiggers3@gmail.com>,
        Tom Herbert <tom@herbertland.com>,
        Andi Kleen <ak@linux.intel.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com>
To: Hannes Frederic Sowa <hannes@stressinduktion.org>
In-Reply-To: <1482420815.2673.1.camel@stressinduktion.org>
Sender: linux-crypto-owner@vger.kernel.org

Hi Hannes,

On Thu, Dec 22, 2016 at 4:33 PM, Hannes Frederic Sowa
<hannes@stressinduktion.org> wrote:
> IPv6 you cannot touch anymore. The hashing algorithm is part of uAPI.
> You don't want to give people new IPv6 addresses with the same stable
> secret (across reboots) after a kernel upgrade. Maybe they lose
> connectivity then and it is extra work?

Ahh, too bad. So it goes.

> The bpf hash stuff can be changed during this merge window, as it is
> not yet in a released kernel. Albeit I would probably have preferred
> something like sha256 here, which can be easily replicated by user
> space tools (minus the problem of patching out references to not
> hashable data, which must be zeroed).

Oh, interesting, so time is of the essence then. Do you want to handle
changing the new eBPF code to something not-SHA1 before it's too late,
as part of a new patchset that can fast track itself to David? And
then I can preserve my large series for the next merge window.

Jason