linux-kernel - Re: [PATCH 3/3] wireguard: device: clear keys on VM fork

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Message-ID: <CAHmME9r6zXw6cByqpbhEBKkvpejrLqGMn55E-uOCQ0V1mQi1LQ@mail.gmail.com>
Date:   Wed, 2 Mar 2022 12:44:45 +0100
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     "Michael S. Tsirkin" <mst@...hat.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Linux Crypto Mailing List <linux-crypto@...r.kernel.org>,
        Netdev <netdev@...r.kernel.org>,
        Alexander Graf <graf@...zon.com>, Jann Horn <jannh@...gle.com>,
        Greg KH <gregkh@...uxfoundation.org>,
        Dominik Brodowski <linux@...inikbrodowski.net>,
        "Theodore Ts'o" <tytso@....edu>, Jakub Kicinski <kuba@...nel.org>
Subject: Re: [PATCH 3/3] wireguard: device: clear keys on VM fork

Hi Michael,

On Wed, Mar 2, 2022 at 9:36 AM Michael S. Tsirkin <mst@...hat.com> wrote:
> Catastrophic cryptographic failure sounds bad :(
> So in another thread we discussed that there's a race with this
> approach, and we don't know how big it is. Question is how expensive
> it would be to fix it properly checking for fork after every use of
> key+nonce and before transmitting it. I did a quick microbenchmark
> and it did not seem too bad - care posting some numbers?

I followed up in that thread, which is a larger one, so it might be
easiest to keep discussion there. My response to you here is the same
as it was over there. :)

https://lore.kernel.org/lkml/CAHmME9pf-bjnZuweoLqoFEmPy1OK7ogEgGEAva1T8uVTufhCuw@mail.gmail.com/

Jason