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

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Message-ID: <CAHmME9ok8iWfZybyDki13v6Xf3usRet1y8oUcDcy+5YwkARQPA@mail.gmail.com>
Date:   Thu, 22 Dec 2016 16:41:59 +0100
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     Hannes Frederic Sowa <hannes@...essinduktion.org>
Cc:     kernel-hardening@...ts.openwall.com,
        "Theodore Ts'o" <tytso@....edu>,
        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

Hi Hannes,

On Thu, Dec 22, 2016 at 4:33 PM, Hannes Frederic Sowa
<hannes@...essinduktion.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