linux-kernel - Re: [PATCH v4 0/7] nvme-tcp: Support receiving KeyUpdate requests

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Message-ID: <fe16288e-e3f2-4de3-838e-181bbb0ce3ee@suse.de>
Date: Mon, 20 Oct 2025 19:46:16 +0200
From: Hannes Reinecke <hare@...e.de>
To: alistair23@...il.com, chuck.lever@...cle.com, hare@...nel.org,
 kernel-tls-handshake@...ts.linux.dev, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
 linux-nvme@...ts.infradead.org, linux-nfs@...r.kernel.org
Cc: kbusch@...nel.org, axboe@...nel.dk, hch@....de, sagi@...mberg.me,
 kch@...dia.com, Alistair Francis <alistair.francis@....com>
Subject: Re: [PATCH v4 0/7] nvme-tcp: Support receiving KeyUpdate requests

On 10/17/25 06:23, alistair23@...il.com wrote:
> From: Alistair Francis <alistair.francis@....com>
> 
> The TLS 1.3 specification allows the TLS client or server to send a
> KeyUpdate. This is generally used when the sequence is about to
> overflow or after a certain amount of bytes have been encrypted.
> 
> The TLS spec doesn't mandate the conditions though, so a KeyUpdate
> can be sent by the TLS client or server at any time. This includes
> when running NVMe-OF over a TLS 1.3 connection.
> 
> As such Linux should be able to handle a KeyUpdate event, as the
> other NVMe side could initiate a KeyUpdate.
> 
> Upcoming WD NVMe-TCP hardware controllers implement TLS support
> and send KeyUpdate requests.
> 
> This series builds on top of the existing TLS EKEYEXPIRED work,
> which already detects a KeyUpdate request. We can now pass that
> information up to the NVMe layer (target and host) and then pass
> it up to userspace.
> 
> Userspace (ktls-utils) will need to save the connection state
> in the keyring during the initial handshake. The kernel then
> provides the key serial back to userspace when handling a
> KeyUpdate. Userspace can use this to restore the connection
> information and then update the keys, this final process
> is similar to the initial handshake.
> 

I am rather sceptical at the current tlshd implementation.
At which place do you update the sending keys?
I'm only seeing a call to 'gnutls_handhake_update_receiving_key()'.

But I haven't found the matching function 
'gnutls_handshake_update_sending_key()' in current gnutls.
So how does updating of the sending keys work?

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                  Kernel Storage Architect
hare@...e.de                                +49 911 74053 688
SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich