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Message-ID: <dc19d073-0266-4143-9c74-08e30a90b875@suse.de>
Date: Mon, 20 Oct 2025 08:22:09 +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 5/7] nvme-tcp: Support KeyUpdate
On 10/17/25 06:23, 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>
> ---
> v4:
> - Remove all support for initiating KeyUpdate
> - Don't call cancel_work() when updating keys
> 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, 51 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
> index 2696bf97dfac..791e0cc91ad8 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;
> @@ -858,7 +859,10 @@ static void nvme_tcp_handle_c2h_term(struct nvme_tcp_queue *queue,
> static int nvme_tcp_recvmsg_pdu(struct nvme_tcp_queue *queue)
> {
> char *pdu = queue->pdu;
> + char cbuf[CMSG_LEN(sizeof(char))] = {};
> struct msghdr msg = {
> + .msg_control = cbuf,
> + .msg_controllen = sizeof(cbuf),
> .msg_flags = MSG_DONTWAIT,
> };
> struct kvec iov = {
> @@ -873,12 +877,17 @@ static int nvme_tcp_recvmsg_pdu(struct nvme_tcp_queue *queue)
> if (ret <= 0)
> return ret;
>
> + hdr = queue->pdu;
> + if (hdr->type == TLS_HANDSHAKE_KEYUPDATE) {
> + dev_err(queue->ctrl->ctrl.device, "KeyUpdate message\n");
> + return 1;
> + }
> +
> queue->pdu_remaining -= ret;
> queue->pdu_offset += ret;
> if (queue->pdu_remaining)
> return 0;
>
> - hdr = queue->pdu;
> if (unlikely(hdr->hlen != sizeof(struct nvme_tcp_rsp_pdu))) {
> if (!nvme_tcp_recv_pdu_supported(hdr->type))
> goto unsupported_pdu;
> @@ -944,6 +953,7 @@ static int nvme_tcp_recvmsg_data(struct nvme_tcp_queue *queue)
> struct request *rq =
> nvme_cid_to_rq(nvme_tcp_tagset(queue), pdu->command_id);
> struct nvme_tcp_request *req = blk_mq_rq_to_pdu(rq);
> + char cbuf[CMSG_LEN(sizeof(char))] = {};
>
> if (nvme_tcp_recv_state(queue) != NVME_TCP_RECV_DATA)
> return 0;
> @@ -973,12 +983,14 @@ static int nvme_tcp_recvmsg_data(struct nvme_tcp_queue *queue)
> memset(&msg, 0, sizeof(msg));
> msg.msg_iter = req->iter;
> msg.msg_flags = MSG_DONTWAIT;
> + msg.msg_control = cbuf,
> + msg.msg_controllen = sizeof(cbuf),
>
Watch out. This is the recvmsg bug Olga had been posting patches for.
Thing is, if there is a control message the networking code will place
the control message payload into the message buffer. But in doing so
it expects the message buffer to be an iovec, not a bio vec.
To handle this properly you'd need to _not_ set the control buffer,
but rather check for 'MSG_CTRUNC' in msg_flags upon return.
Then you have to setup a new message with msg_control set and
a suitable msg_len (5 bytes, wasn't it?) and re-issue recvmsg
with that message.
And keep fingers crossed that you don't get MSG_CTRUNC on every
call to recvmsg() ...
> ret = sock_recvmsg(queue->sock, &msg, msg.msg_flags);
> if (ret < 0) {
> - dev_err(queue->ctrl->ctrl.device,
> - "queue %d failed to receive request %#x data",
> - nvme_tcp_queue_id(queue), rq->tag);
> + dev_dbg(queue->ctrl->ctrl.device,
> + "queue %d failed to receive request %#x data, %d",
> + nvme_tcp_queue_id(queue), rq->tag, ret);
> return ret;
> }
> if (queue->data_digest)
> @@ -1381,17 +1393,42 @@ 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) {
> + return -EAGAIN;
> + } 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);
> }
>
> +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);
> +
> + 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 =
> @@ -1414,8 +1451,11 @@ static void nvme_tcp_io_work(struct work_struct *w)
> 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 +1763,7 @@ 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;
Hmm. I wonder, do we need to store the generation number somewhere?
Currently the sysfs interface is completely oblivious that a key update
has happened. I really would like to have _some_ indicator there telling
us that a key update had happened, and the generation number would be
ideal here.
> }
>
> out_complete:
> @@ -1752,6 +1793,7 @@ 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);
> if (keyupdate == HANDSHAKE_KEY_UPDATE_TYPE_UNSPEC)
Chers,
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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