netdev - Re: [PATCH 6/8] nvme-tcp: Support KeyUpdate

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Message-ID: <107506e2-7870-45df-b595-583b57137a29@suse.de>
Date: Mon, 18 Aug 2025 14:52:14 +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 6/8] nvme-tcp: Support KeyUpdate

On 8/15/25 07:02, alistair23@...il.com wrote:
> From: Alistair Francis <alistair.francis@....com>
> 
> If the nvme_tcp_try_send() or nvme_tcp_try_recv() functions return
> EKEYEXPIRED then the underlying TLS keys need to be updated. This occurs
> on an KeyUpdate event.
> 
> If the NVMe Target (TLS server) initiates a KeyUpdate this patch will
> allow the NVMe layer to process the KeyUpdate request and forward the
> request to userspace. Userspace must then update the key to keep the
> connection alive.
> 
> This patch allows us to handle the NVMe target sending a KeyUpdate
> request without aborting the connection. At this time we don't support
> initiating a KeyUpdate.
> 
> Link: https://datatracker.ietf.org/doc/html/rfc8446#section-4.6.3
> Signed-off-by: Alistair Francis <alistair.francis@....com>
> ---
>   drivers/nvme/host/tcp.c | 63 ++++++++++++++++++++++++++++++++++++++++-
>   1 file changed, 62 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
> index cc3332529355..0c14d3ad58af 100644
> --- a/drivers/nvme/host/tcp.c
> +++ b/drivers/nvme/host/tcp.c
> @@ -171,6 +171,7 @@ struct nvme_tcp_queue {
>   	bool			tls_enabled;
>   	u32			rcv_crc;
>   	u32			snd_crc;
> +	key_serial_t		user_key_serial;
>   	__le32			exp_ddgst;
>   	__le32			recv_ddgst;
>   	struct completion       tls_complete;
> @@ -1313,6 +1314,7 @@ static int nvme_tcp_try_send(struct nvme_tcp_queue *queue)
>   	struct nvme_tcp_request *req;
>   	unsigned int noreclaim_flag;
>   	int ret = 1;
> +	enum nvme_ctrl_state state = nvme_ctrl_state(&(queue->ctrl->ctrl));
>   
>   	if (!queue->request) {
>   		queue->request = nvme_tcp_fetch_request(queue);
> @@ -1347,6 +1349,29 @@ static int nvme_tcp_try_send(struct nvme_tcp_queue *queue)
>   done:
>   	if (ret == -EAGAIN) {
>   		ret = 0;
> +	} else if (ret == -EKEYEXPIRED &&
> +		state != NVME_CTRL_CONNECTING &&
> +		state != NVME_CTRL_RESETTING) {
> +		int qid = nvme_tcp_queue_id(queue);
> +
> +		dev_dbg(queue->ctrl->ctrl.device,
> +			"updating key for queue %d\n", qid);
> +
> +		nvme_change_ctrl_state(&(queue->ctrl->ctrl), NVME_CTRL_RESETTING);

Rah. Don't do that.
The 'resetting' state is tied to the resetting mechanism
(LIVE->RESETTING->CONNECTING->LIVE) and is being relied on
for the timeout handler. Setting it manually will confuse error
handling.

And really, having the key update in two places is a bit ... odd.
I'd rather stop the I/O queue in nvme_tcp_io_work() once a
EKEYEXPIRED error has been hit, and start the key update via
nvme_tcp_start_tls() function directly from there.
No need to change the controller state.

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