netdev - Re: [PATCH v2 3/4] nvmet-tcp: fix handling of tls alerts

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Message-ID: <CAN-5tyF=5oQLyy7ikbbhFW10OrUfHh0Sr3D=G1nHN+pEsfiSzw@mail.gmail.com>
Date: Fri, 5 Sep 2025 12:10:21 -0400
From: Olga Kornievskaia <aglo@...ch.edu>
To: Olga Kornievskaia <okorniev@...hat.com>
Cc: chuck.lever@...cle.com, jlayton@...nel.org, trondmy@...merspace.com, 
	anna.schumaker@...cle.com, hch@....de, sagi@...mberg.me, kch@...dia.com, 
	davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com, 
	linux-nfs@...r.kernel.org, linux-nvme@...ts.infradead.org, 
	netdev@...r.kernel.org, kernel-tls-handshake@...ts.linux.dev, neil@...wn.name, 
	Dai.Ngo@...cle.com, tom@...pey.com, hare@...e.de, horms@...nel.org, 
	kbusch@...nel.org
Subject: Re: [PATCH v2 3/4] nvmet-tcp: fix handling of tls alerts

Dear NvME maintainers,

Are there objections to this patch? What's the path forward to
including it in the nvme code.

Thank you.

On Thu, Jul 31, 2025 at 2:01 PM Olga Kornievskaia <okorniev@...hat.com> wrote:
>
> Revert kvec msg iterator before trying to process a TLS alert
> when possible.
>
> In nvmet_tcp_try_recv_data(), it's assumed that no msg control
> message buffer is set prior to sock_recvmsg(). Hannes suggested
> that upon detecting that TLS control message is received log a
> message and error out. Left comments in the code for the future
> improvements.
>
> Fixes: a1c5dd8355b1 ("nvmet-tcp: control messages for recvmsg()")
> Suggested-by: Hannes Reinecke <hare@...e.de>
> Reviewed-by: Hannes Reinecky <hare@...u.de>
> Signed-off-by: Olga Kornievskaia <okorniev@...hat.com>
> ---
>  drivers/nvme/target/tcp.c | 31 +++++++++++++++++++------------
>  1 file changed, 19 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/nvme/target/tcp.c b/drivers/nvme/target/tcp.c
> index 688033b88d38..98cee10de713 100644
> --- a/drivers/nvme/target/tcp.c
> +++ b/drivers/nvme/target/tcp.c
> @@ -120,7 +120,6 @@ struct nvmet_tcp_cmd {
>         u32                             pdu_len;
>         u32                             pdu_recv;
>         int                             sg_idx;
> -       char                            recv_cbuf[CMSG_LEN(sizeof(char))];
>         struct msghdr                   recv_msg;
>         struct bio_vec                  *iov;
>         u32                             flags;
> @@ -1161,6 +1160,7 @@ static int nvmet_tcp_try_recv_pdu(struct nvmet_tcp_queue *queue)
>         if (unlikely(len < 0))
>                 return len;
>         if (queue->tls_pskid) {
> +               iov_iter_revert(&msg.msg_iter, len);
>                 ret = nvmet_tcp_tls_record_ok(queue, &msg, cbuf);
>                 if (ret < 0)
>                         return ret;
> @@ -1217,19 +1217,28 @@ static void nvmet_tcp_prep_recv_ddgst(struct nvmet_tcp_cmd *cmd)
>  static int nvmet_tcp_try_recv_data(struct nvmet_tcp_queue *queue)
>  {
>         struct nvmet_tcp_cmd  *cmd = queue->cmd;
> -       int len, ret;
> +       int len;
>
>         while (msg_data_left(&cmd->recv_msg)) {
> +               /* to detect that we received a TlS alert, we assumed that
> +                * cmg->recv_msg's control buffer is not setup. kTLS will
> +                * return an error when no control buffer is set and
> +                * non-tls-data payload is received.
> +                */
>                 len = sock_recvmsg(cmd->queue->sock, &cmd->recv_msg,
>                         cmd->recv_msg.msg_flags);
> +               if (cmd->recv_msg.msg_flags & MSG_CTRUNC) {
> +                       if (len == 0 || len == -EIO) {
> +                               pr_err("queue %d: unhandled control message\n",
> +                                      queue->idx);
> +                               /* note that unconsumed TLS control message such
> +                                * as TLS alert is still on the socket.
> +                                */
> +                               return -EAGAIN;
> +                       }
> +               }
>                 if (len <= 0)
>                         return len;
> -               if (queue->tls_pskid) {
> -                       ret = nvmet_tcp_tls_record_ok(cmd->queue,
> -                                       &cmd->recv_msg, cmd->recv_cbuf);
> -                       if (ret < 0)
> -                               return ret;
> -               }
>
>                 cmd->pdu_recv += len;
>                 cmd->rbytes_done += len;
> @@ -1267,6 +1276,7 @@ static int nvmet_tcp_try_recv_ddgst(struct nvmet_tcp_queue *queue)
>         if (unlikely(len < 0))
>                 return len;
>         if (queue->tls_pskid) {
> +               iov_iter_revert(&msg.msg_iter, len);
>                 ret = nvmet_tcp_tls_record_ok(queue, &msg, cbuf);
>                 if (ret < 0)
>                         return ret;
> @@ -1453,10 +1463,6 @@ static int nvmet_tcp_alloc_cmd(struct nvmet_tcp_queue *queue,
>         if (!c->r2t_pdu)
>                 goto out_free_data;
>
> -       if (queue->state == NVMET_TCP_Q_TLS_HANDSHAKE) {
> -               c->recv_msg.msg_control = c->recv_cbuf;
> -               c->recv_msg.msg_controllen = sizeof(c->recv_cbuf);
> -       }
>         c->recv_msg.msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL;
>
>         list_add_tail(&c->entry, &queue->free_list);
> @@ -1736,6 +1742,7 @@ static int nvmet_tcp_try_peek_pdu(struct nvmet_tcp_queue *queue)
>                 return len;
>         }
>
> +       iov_iter_revert(&msg.msg_iter, len);
>         ret = nvmet_tcp_tls_record_ok(queue, &msg, cbuf);
>         if (ret < 0)
>                 return ret;
> --
> 2.47.1
>
>