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Message-ID: <591a7eb8-563c-4368-b868-880ed081a432@suse.de>
Date: Mon, 6 Oct 2025 08:48:44 +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 7/8] nvmet-tcp: Support KeyUpdate
On 10/3/25 06:31, alistair23@...il.com wrote:
> From: Alistair Francis <alistair.francis@....com>
>
> If the nvmet_tcp_try_recv() function return EKEYEXPIRED or if we receive
> a KeyUpdate handshake type then the underlying TLS keys need to be
> updated.
>
> If the NVMe Host (TLS client) 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 host 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:
> - Use a write lock for sk_user_data
> - Fix build with CONFIG_NVME_TARGET_TCP_TLS disabled
> - Remove unused variable
> v2:
> - Use a helper function for KeyUpdates
> - Ensure keep alive timer is stopped
> - Wait for TLS KeyUpdate to complete
>
> drivers/nvme/target/tcp.c | 90 ++++++++++++++++++++++++++++++++++++---
> 1 file changed, 85 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/nvme/target/tcp.c b/drivers/nvme/target/tcp.c
> index bee0355195f5..fd59dd3ca632 100644
> --- a/drivers/nvme/target/tcp.c
> +++ b/drivers/nvme/target/tcp.c
> @@ -175,6 +175,7 @@ struct nvmet_tcp_queue {
>
> /* TLS state */
> key_serial_t tls_pskid;
> + key_serial_t user_session_id;
> struct delayed_work tls_handshake_tmo_work;
>
> unsigned long poll_end;
> @@ -186,6 +187,8 @@ struct nvmet_tcp_queue {
> struct sockaddr_storage sockaddr_peer;
> struct work_struct release_work;
>
> + struct completion tls_complete;
> +
> int idx;
> struct list_head queue_list;
>
> @@ -836,6 +839,11 @@ static int nvmet_tcp_try_send_one(struct nvmet_tcp_queue *queue,
> return 1;
> }
>
> +#ifdef CONFIG_NVME_TARGET_TCP_TLS
> +static int nvmet_tcp_try_peek_pdu(struct nvmet_tcp_queue *queue);
> +static void nvmet_tcp_tls_handshake_timeout(struct work_struct *w);
> +#endif
> +
> static int nvmet_tcp_try_send(struct nvmet_tcp_queue *queue,
> int budget, int *sends)
> {
And we need this why?
> @@ -844,6 +852,13 @@ static int nvmet_tcp_try_send(struct nvmet_tcp_queue *queue,
> for (i = 0; i < budget; i++) {
> ret = nvmet_tcp_try_send_one(queue, i == budget - 1);
> if (unlikely(ret < 0)) {
> +#ifdef CONFIG_NVME_TARGET_TCP_TLS
> + if (ret == -EKEYEXPIRED &&
> + queue->state != NVMET_TCP_Q_DISCONNECTING &&
> + queue->state != NVMET_TCP_Q_TLS_HANDSHAKE) {
> + goto done;
> + }
> +#endif
> nvmet_tcp_socket_error(queue, ret);
> goto done;
> } else if (ret == 0) {
See my comment to the host patches. Handling an incoming KeyUpdate is
vastly different than initiating a KeyUpdate. _and_ the network stack
will only ever return -EKEYEXPIRED on receive.
So please split the patches in handling an incoming KeyUpdate and
initiating a KeyUpdate.
> @@ -1110,6 +1125,45 @@ static inline bool nvmet_tcp_pdu_valid(u8 type)
> return false;
> }
>
> +#ifdef CONFIG_NVME_TARGET_TCP_TLS
> +static int update_tls_keys(struct nvmet_tcp_queue *queue)
> +{
> + int ret;
> +
> + cancel_work(&queue->io_work);
> + queue->state = NVMET_TCP_Q_TLS_HANDSHAKE;
> +
> + /* Restore the default callbacks before starting upcall */
> + write_lock_bh(&queue->sock->sk->sk_callback_lock);
> + queue->sock->sk->sk_data_ready = queue->data_ready;
> + queue->sock->sk->sk_state_change = queue->state_change;
> + queue->sock->sk->sk_write_space = queue->write_space;
> + queue->sock->sk->sk_user_data = NULL;
> + write_unlock_bh(&queue->sock->sk->sk_callback_lock);
> +
We do have a function for this ...
> + nvmet_stop_keep_alive_timer(queue->nvme_sq.ctrl);
> +
> + INIT_DELAYED_WORK(&queue->tls_handshake_tmo_work,
> + nvmet_tcp_tls_handshake_timeout);
> +
> + ret = nvmet_tcp_tls_handshake(queue, HANDSHAKE_KEY_UPDATE_TYPE_RECEIVED);
> +
> + if (ret < 0)
> + return ret;
> +
> + ret = wait_for_completion_interruptible_timeout(&queue->tls_complete, 10 * HZ);
> +
> + if (ret <= 0) {
> + tls_handshake_cancel(queue->sock->sk);
> + return ret;
> + }
> +
> + queue->state = NVMET_TCP_Q_LIVE;
> +
> + return ret;
> +}
> +#endif
> +
> static int nvmet_tcp_tls_record_ok(struct nvmet_tcp_queue *queue,
> struct msghdr *msg, char *cbuf)
> {
> @@ -1135,6 +1189,9 @@ static int nvmet_tcp_tls_record_ok(struct nvmet_tcp_queue *queue,
> ret = -EAGAIN;
> }
> break;
> + case TLS_RECORD_TYPE_HANDSHAKE:
> + ret = -EAGAIN;
> + break;
Shouldn't this be rather -EKEYEXPIRED?
> default:
> /* discard this record type */
> pr_err("queue %d: TLS record %d unhandled\n",
> @@ -1344,6 +1401,13 @@ static int nvmet_tcp_try_recv(struct nvmet_tcp_queue *queue,
> for (i = 0; i < budget; i++) {
> ret = nvmet_tcp_try_recv_one(queue);
> if (unlikely(ret < 0)) {
> +#ifdef CONFIG_NVME_TARGET_TCP_TLS
> + if (ret == -EKEYEXPIRED &&
> + queue->state != NVMET_TCP_Q_DISCONNECTING &&
> + queue->state != NVMET_TCP_Q_TLS_HANDSHAKE) {
> + goto done;
> + }
> +#endif
> nvmet_tcp_socket_error(queue, ret);
> goto done;
> } else if (ret == 0) {
> @@ -1408,14 +1472,26 @@ static void nvmet_tcp_io_work(struct work_struct *w)
> ret = nvmet_tcp_try_recv(queue, NVMET_TCP_RECV_BUDGET, &ops);
> if (ret > 0)
> pending = true;
> - else if (ret < 0)
> - return;
> + else if (ret < 0) {
> +#ifdef CONFIG_NVME_TARGET_TCP_TLS
> + if (ret == -EKEYEXPIRED)
> + update_tls_keys(queue);
> + else
> +#endif
> + return;
> + }
>
> ret = nvmet_tcp_try_send(queue, NVMET_TCP_SEND_BUDGET, &ops);
> if (ret > 0)
> pending = true;
> - else if (ret < 0)
> - return;
> + else if (ret < 0) {
> +#ifdef CONFIG_NVME_TARGET_TCP_TLS
> + if (ret == -EKEYEXPIRED)
> + update_tls_keys(queue);
> + else
> +#endif
> + return;
> + }
>
> } while (pending && ops < NVMET_TCP_IO_WORK_BUDGET);
>
Wouldn't it be better to move the call to 'update_tls_keys()' out of
the loop and just requeue io_work afterwards?
> @@ -1798,6 +1874,7 @@ static void nvmet_tcp_tls_handshake_done(void *data, int status,
> }
> if (!status) {
> queue->tls_pskid = peerid;
> + queue->user_session_id = user_session_id;
> queue->state = NVMET_TCP_Q_CONNECTING;
> } else
> queue->state = NVMET_TCP_Q_FAILED;
> @@ -1813,6 +1890,7 @@ static void nvmet_tcp_tls_handshake_done(void *data, int status,
> else
> nvmet_tcp_set_queue_sock(queue);
> kref_put(&queue->kref, nvmet_tcp_release_queue);
> + complete(&queue->tls_complete);
> }
>
> static void nvmet_tcp_tls_handshake_timeout(struct work_struct *w)
> @@ -1843,7 +1921,7 @@ static int nvmet_tcp_tls_handshake(struct nvmet_tcp_queue *queue,
> int ret = -EOPNOTSUPP;
> struct tls_handshake_args args;
>
> - if (queue->state != NVMET_TCP_Q_TLS_HANDSHAKE) {
> + if (queue->state != NVMET_TCP_Q_TLS_HANDSHAKE && !keyupdate) {
> pr_warn("cannot start TLS in state %d\n", queue->state);
> return -EINVAL;
>
Why? Shouldn't we always set the HANDSHAKE state?
> @@ -1856,7 +1934,9 @@ static int nvmet_tcp_tls_handshake(struct nvmet_tcp_queue *queue,
> args.ta_data = queue;
> args.ta_keyring = key_serial(queue->port->nport->keyring);
> args.ta_timeout_ms = tls_handshake_timeout * 1000;
> + args.user_session_id = queue->user_session_id;
>
> + init_completion(&queue->tls_complete);
> ret = tls_server_hello_psk(&args, GFP_KERNEL, keyupdate);
> if (ret) {
> kref_put(&queue->kref, nvmet_tcp_release_queue)
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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