Re: [PATCH v7 4/5] nvme-tcp: Support KeyUpdate

[Alistair Francis]

On Wed, Mar 4, 2026 at 5:40 PM Hannes Reinecke <hare@xxxxxxx> wrote:
>
> On 3/4/26 06:34, alistair23@xxxxxxxxx wrote:
> > From: Alistair Francis <alistair.francis@xxxxxxx>
> >
> > 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 as described in RFC8446
> > https://datatracker.ietf.org/doc/html/rfc8446#section-4.6.3.
> >
> > 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.
> >
> > Signed-off-by: Alistair Francis <alistair.francis@xxxxxxx>
> > ---
> > v7:
> >   - Use read_sock_cmsg instead of recvmsg() to handle KeyUpdate
> > v6:
> >   - Don't use `struct nvme_tcp_hdr` to determine TLS_HANDSHAKE_KEYUPDATE,
> >     instead look at the cmsg fields.
> >   - Don't flush async_event_work
> > v5:
> >   - Cleanup code flow
> >   - Check for MSG_CTRUNC in the msg_flags return from recvmsg
> >     and use that to determine if it's a control message
> > 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 | 59 ++++++++++++++++++++++++++++++++++++++++-
> >   1 file changed, 58 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
> > index 8b6172dd1c0f..ade11d2ac9ef 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            handshake_session_id;
> >       __le32                  exp_ddgst;
> >       __le32                  recv_ddgst;
> >       struct completion       tls_complete;
> > @@ -1361,6 +1362,59 @@ static int nvme_tcp_try_send(struct nvme_tcp_queue *queue)
> >       return ret;
> >   }
> >
> > +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);
> > +
> > +     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);
> > +     }
> > +}
> > +
> > +static int nvme_tcp_recv_cmsg(read_descriptor_t *desc,
> > +                           struct sk_buff *skb,
> > +                           unsigned int offset, size_t len,
> > +                           u8 content_type)
> > +{
> > +     struct nvme_tcp_queue *queue = desc->arg.data;
> > +     struct socket *sock = queue->sock;
> > +     struct sock *sk = sock->sk;
> > +
> > +     switch (content_type) {
> > +     case TLS_RECORD_TYPE_HANDSHAKE:
> > +             if (len == 5) {
> > +                     u8 header[5];
> > +
> > +                     if (!skb_copy_bits(skb, offset, header,
> > +                                        sizeof(header))) {
> > +                             if (header[0] == TLS_HANDSHAKE_KEYUPDATE) {
> > +                                     dev_err(queue->ctrl->ctrl.device, "KeyUpdate message\n");
> > +                                     release_sock(sk);
> > +                                     update_tls_keys(queue);
> > +                                     lock_sock(sk);
> > +                                     return 0;
> > +                             }
> > +                     }
> > +             }
> > +
> > +             break;
> > +     default:
> > +             break;
> > +     }
>
> I think a simple 'if' condition would be sufficient here, or do you have
> handling of other TLS record types queued somewhere?
> And we should log unhandled TLS records.

I like this approach as it makes it really easy to handle more types
in the future. I don't have any more record types queued anywhere so I
can change it to an if statement.

Good point about logging unhandled records

Alistair

>
> > +
> > +     return -EAGAIN;
> > +}
> > +
> >   static int nvme_tcp_try_recv(struct nvme_tcp_queue *queue)
> >   {
> >       struct socket *sock = queue->sock;
> > @@ -1372,7 +1426,8 @@ static int nvme_tcp_try_recv(struct nvme_tcp_queue *queue)
> >       rd_desc.count = 1;
> >       lock_sock(sk);
> >       queue->nr_cqe = 0;
> > -     consumed = sock->ops->read_sock(sk, &rd_desc, nvme_tcp_recv_skb);
> > +     consumed = sock->ops->read_sock_cmsg(sk, &rd_desc, nvme_tcp_recv_skb,
> > +                                          nvme_tcp_recv_cmsg);
> >       release_sock(sk);
> >       return consumed == -EAGAIN ? 0 : consumed;
> >   }
> > @@ -1708,6 +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->handshake_session_id = handshake_session_id;
> >       }
> >
> >   out_complete:
> > @@ -1737,6 +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.ta_handshake_session_id = queue->handshake_session_id;
> >       queue->tls_err = -EOPNOTSUPP;
> >       init_completion(&queue->tls_complete);
> >       if (keyupdate == HANDSHAKE_KEY_UPDATE_TYPE_UNSPEC)
>
> Otherwise looks good.
>
> Cheers,
>
> Hannes
> --
> Dr. Hannes Reinecke                  Kernel Storage Architect
> hare@xxxxxxx                                +49 911 74053 688
> SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
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