Re: [PATCH net-next v2 2/6] net: Introduce read_sock_rectype proto_ops for control record delivery

On 7/20/26 4:27 PM, Chuck Lever wrote:
> From: Chuck Lever <[email protected]>
> 
> Kernel TCP consumers that use the read_sock interface
> (proto_ops.read_sock) cannot receive TLS control messages (Alerts,
> Handshake records) when kTLS is active. The current
> tls_sw_read_sock() method rejects non-data records with -EINVAL, and
> the sk_read_actor_t callback has no channel for delivering record-
> type metadata.
> 
> Four kernel subsystems are affected: NFSD (sunrpc svcsock), NFS
> client (sunrpc xprtsock), NVMe target (nvmet-tcp), and NVMe host
> (nvme-tcp). Each of these either falls back to the sock_recvmsg()
> API or lacks TLS alert handling entirely.
> 
> A new read_sock_rectype method in struct proto_ops provides a
> separate code path that delivers non-data TLS records to a callback,
> without changing the behavior seen by existing read_sock consumers.
> 
> The new sk_read_rectype_actor_t callback type extends the
> sk_read_actor_t signature with a rectype parameter carrying the
> protocol-layer record type (for example, TLS_RECORD_TYPE_ALERT). The
> record-type callback returns 0 to consume a record or a negative
> value to requeue it and stop delivery; unlike the data callback, its
> return value does not count bytes.
> 
> Signed-off-by: Chuck Lever <[email protected]>
> ---
>   include/linux/net.h | 28 ++++++++++++++++++++++++++++
>   1 file changed, 28 insertions(+)
> 
> diff --git a/include/linux/net.h b/include/linux/net.h
> index 277188a40c72..7a19a743a617 100644
> --- a/include/linux/net.h
> +++ b/include/linux/net.h
> @@ -198,6 +198,13 @@ struct sk_buff;
>   struct proto_accept_arg;
>   typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *,
>   			       unsigned int, size_t);
> +/* rectype carries the transport record type, for example a
> + * TLS_RECORD_TYPE_* value.
> + */
> +typedef int (*sk_read_rectype_actor_t)(read_descriptor_t *,
> +				       struct sk_buff *,
> +				       unsigned int, size_t,
> +				       u8 rectype);
>   typedef int (*skb_read_actor_t)(struct sock *, struct sk_buff *);
>   
>   
> @@ -264,6 +271,27 @@ struct proto_ops {
>   	 */
>   	int		(*read_sock)(struct sock *sk, read_descriptor_t *desc,
>   				     sk_read_actor_t recv_actor);
> +	/*
> +	 * read_sock_rectype splits delivery across two callbacks:
> +	 * recv_actor for data records, per the sk_read_actor_t
> +	 * convention, and rectype_actor for all other records,
> +	 * with rectype identifying each. A NULL rectype_actor
> +	 * leaves non-data records pending. rectype_actor returns 0
> +	 * to consume a record or negative to leave it pending for
> +	 * redelivery and stop delivery; the negative return is a
> +	 * backpressure signal, not a fatal error. Both callbacks
> +	 * report errors and early stop the way recv_actor does:
> +	 * by setting desc->count to 0 and recording the reason in
> +	 * desc->error, per the read_descriptor_t convention and
> +	 * independent of the return value. The return value reports
> +	 * only data bytes consumed by recv_actor; the caller
> +	 * detects an error or early stop via desc->count and
> +	 * desc->error.
> +	 */
> +	int		(*read_sock_rectype)(struct sock *sk,
> +					     read_descriptor_t *desc,
> +					     sk_read_actor_t recv_actor,
> +					     sk_read_rectype_actor_t rectype_actor);
>   	/* This is different from read_sock(), it reads an entire skb at a time. */
>   	int		(*read_skb)(struct sock *sk, skb_read_actor_t recv_actor);
>   	int		(*sendmsg_locked)(struct sock *sk, struct msghdr *msg,
> 

Naming is a bit odd, but hey.

Reviewed-by: Hannes Reinecke <[email protected]>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                  Kernel Storage Architect
[email protected]                                +49 911 74053 688
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