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

From: Jason A. Donenfeld
Date: Thu Dec 22 2016 - 10:42:10 EST


Hi Hannes,

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