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Message-ID: <00b0fca9-e9d1-4d04-9a43-5fe3d047e4d6@suse.de>
Date: Mon, 6 Oct 2025 08:34:34 +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 v3 6/8] nvme-tcp: Support KeyUpdate
On 10/3/25 06:31, 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>
> ---
> v3:
> - Don't cancel existing handshake requests
> v2:
> - Don't change the state
> - Use a helper function for KeyUpdates
> - Continue sending in nvme_tcp_send_all() after a KeyUpdate
> - Remove command message using recvmsg
>
> drivers/nvme/host/tcp.c | 60 ++++++++++++++++++++++++++++++++++++-----
> 1 file changed, 54 insertions(+), 6 deletions(-)
>
Weelll ... Checking the code the network stack will only return
-EKEYEXPIRED on recvmsg() (as it parses the TLS message on receive).
So really this is handling an incoming KeyUpdate request only.
And I would keep it that way, as initiating a KeyUpdate request
is quite different (conceptually) than handling an incoming one.
> diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
> index b07401ad68eb..4f27319f0078 100644
> --- a/drivers/nvme/host/tcp.c
> +++ b/drivers/nvme/host/tcp.c
> @@ -172,6 +172,7 @@ struct nvme_tcp_queue {
> bool tls_enabled;
> u32 rcv_crc;
> u32 snd_crc;
> + key_serial_t user_session_id;
> __le32 exp_ddgst;
> __le32 recv_ddgst;
> struct completion tls_complete;
> @@ -211,6 +212,7 @@ static int nvme_tcp_start_tls(struct nvme_ctrl *nctrl,
> struct nvme_tcp_queue *queue,
> key_serial_t pskid,
> handshake_key_update_type keyupdate);
> +static void update_tls_keys(struct nvme_tcp_queue *queue);
>
> static inline struct nvme_tcp_ctrl *to_tcp_ctrl(struct nvme_ctrl *ctrl)
> {
> @@ -394,6 +396,14 @@ static inline void nvme_tcp_send_all(struct nvme_tcp_queue *queue)
> do {
> ret = nvme_tcp_try_send(queue);
> } while (ret > 0);
> +
> + if (ret == -EKEYEXPIRED) {
> + update_tls_keys(queue);
> +
> + do {
> + ret = nvme_tcp_try_send(queue);
> + } while (ret > 0);
> + }
> }
>
See above. I'd rather have two patches, one for handling incoming
KeyUpdate message (where we'd see an EKEYEXPIRED on receive), and
another one for initiating KeyUpdates.
> static inline bool nvme_tcp_queue_has_pending(struct nvme_tcp_queue *queue)
> @@ -1346,6 +1356,8 @@ static int nvme_tcp_try_send(struct nvme_tcp_queue *queue)
> done:
> if (ret == -EAGAIN) {
> ret = 0;
> + } else if (ret == -EKEYEXPIRED) {
> + goto out;
> } else if (ret < 0) {
> dev_err(queue->ctrl->ctrl.device,
> "failed to send request %d\n", ret);
See above.
> @@ -1381,17 +1393,45 @@ static int nvme_tcp_try_recvmsg(struct nvme_tcp_queue *queue)
> }
> } while (result >= 0);
>
> - if (result < 0 && result != -EAGAIN) {
> + if (result == -EKEYEXPIRED) {
> + return -EKEYEXPIRED;
> + } else if (result == -EAGAIN) {
> + result = 0;
> + } else if (result < 0) {
> dev_err(queue->ctrl->ctrl.device,
> "receive failed: %d\n", result);
> queue->rd_enabled = false;
> nvme_tcp_error_recovery(&queue->ctrl->ctrl);
> - } else if (result == -EAGAIN)
> - result = 0;
> + }
>
> return result < 0 ? result : (queue->nr_cqe = nr_cqe);
> }
>
Remind me again to resend my tcp_recvmsg patch. The blanking out
of -EAGAIN is actually wrong.
> +static void update_tls_keys(struct nvme_tcp_queue *queue)
> +{
> + int qid = nvme_tcp_queue_id(queue);
> + int ret;
> +
> + dev_dbg(queue->ctrl->ctrl.device,
> + "updating key for queue %d\n", qid);
> +
> + cancel_work(&queue->io_work);
> +
Hmm.
You issue a 'cancel_work()', but later on you call this
function from within the workqueue context. Not a great
idea.
I'd rather calling 'update_tls_keys()' from io_work() only,
and drop the 'cancel_work()' invocation as that would be
pointless now.
> + nvme_stop_keep_alive(&(queue->ctrl->ctrl));
> + flush_work(&(queue->ctrl->ctrl).async_event_work);
> +
> + ret = nvme_tcp_start_tls(&(queue->ctrl->ctrl),
> + queue, queue->ctrl->ctrl.tls_pskid,
> + HANDSHAKE_KEY_UPDATE_TYPE_RECEIVED);
> +
> + if (ret < 0) {
> + dev_err(queue->ctrl->ctrl.device,
> + "failed to update the keys %d\n", ret);
> + nvme_tcp_fail_request(queue->request);
> + nvme_tcp_done_send_req(queue);
> + }
> +}
> +
> static void nvme_tcp_io_work(struct work_struct *w)
> {
> struct nvme_tcp_queue *queue =
> @@ -1407,15 +1447,21 @@ static void nvme_tcp_io_work(struct work_struct *w)
> mutex_unlock(&queue->send_mutex);
> if (result > 0)
> pending = true;
> - else if (unlikely(result < 0))
> + else if (unlikely(result < 0)) {
> + if (result == -EKEYEXPIRED)
> + update_tls_keys(queue);
> break;
> + }
> }
>
> result = nvme_tcp_try_recvmsg(queue);
> if (result > 0)
> pending = true;
> - else if (unlikely(result < 0))
> - return;
> + else if (unlikely(result < 0)) {
> + if (result == -EKEYEXPIRED)
> + update_tls_keys(queue);
> + break;
> + }
>
> /* did we get some space after spending time in recv? */
> if (nvme_tcp_queue_has_pending(queue) &&
> @@ -1723,6 +1769,7 @@ static void nvme_tcp_tls_done(void *data, int status, key_serial_t pskid,
> ctrl->ctrl.tls_pskid = key_serial(tls_key);
> key_put(tls_key);
> queue->tls_err = 0;
> + queue->user_session_id = user_session_id;
> }
>
> out_complete:
> @@ -1752,6 +1799,7 @@ static int nvme_tcp_start_tls(struct nvme_ctrl *nctrl,
> keyring = key_serial(nctrl->opts->keyring);
> args.ta_keyring = keyring;
> args.ta_timeout_ms = tls_handshake_timeout * 1000;
> + args.user_session_id = queue->user_session_id;
> queue->tls_err = -EOPNOTSUPP;
> init_completion(&queue->tls_complete);
> ret = tls_client_hello_psk(&args, GFP_KERNEL, keyupdate);
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
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