Re: [PATCH v10 12/18] virtio/vsock: add SEQPACKET receive logic

[Stefano Garzarella <sgarzare@xxxxxxxxxx>]

On Thu, May 20, 2021 at 10:18:21PM +0300, Arseny Krasnov wrote:
> Update current receive logic for SEQPACKET support: performs
> check for packet and socket types on receive(if mismatch, then
> reset connection).

We also copy the flags. Please check better your commit messages.

> Signed-off-by: Arseny Krasnov <arseny.krasnov@xxxxxxxxxxxxx>
> ---
> v9 -> v10:
> 1) Commit message updated.
> 2) Comment updated.
> 3) Updated way to to set 'last_pkt' flags.
>
> net/vmw_vsock/virtio_transport_common.c | 30 ++++++++++++++++++++++---
> 1 file changed, 27 insertions(+), 3 deletions(-)
>
> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
> index 61349b2ea7fe..a6f8b0f39775 100644
> --- a/net/vmw_vsock/virtio_transport_common.c
> +++ b/net/vmw_vsock/virtio_transport_common.c
> @@ -165,6 +165,14 @@ void virtio_transport_deliver_tap_pkt(struct virtio_vsock_pkt *pkt)
> }
> EXPORT_SYMBOL_GPL(virtio_transport_deliver_tap_pkt);
>
> +static u16 virtio_transport_get_type(struct sock *sk)
> +{
> +	if (sk->sk_type == SOCK_STREAM)
> +		return VIRTIO_VSOCK_TYPE_STREAM;
> +	else
> +		return VIRTIO_VSOCK_TYPE_SEQPACKET;
> +}
> +
> /* This function can only be used on connecting/connected sockets,
>  * since a socket assigned to a transport is required.
>  *
> @@ -979,13 +987,17 @@ virtio_transport_recv_enqueue(struct vsock_sock *vsk,
> 					   struct virtio_vsock_pkt, list);
>
> 		/* If there is space in the last packet queued, we copy the
> -		 * new packet in its buffer.
> +		 * new packet in its buffer(except SEQPACKET case, when we
> +		 * also check that last packet is not last packet of previous
> +		 * record).

Is better to explain why we don't do this for SEQPACKET, something like this:

		/* If there is space in the last packet queued, we copy the
		 * new packet in its buffer.
		 * We avoid this if the last packet queued has
		 * VIRTIO_VSOCK_SEQ_EOR set, because it is the delimiter
		 * of SEQPACKET record, so `pkt` is the first packet
		 * of a new record.
		 */

> 		 */
> -		if (pkt->len <= last_pkt->buf_len - last_pkt->len) {
> +		if ((pkt->len <= last_pkt->buf_len - last_pkt->len) &&
> +		    !(le32_to_cpu(last_pkt->hdr.flags) & VIRTIO_VSOCK_SEQ_EOR)) {
> 			memcpy(last_pkt->buf + last_pkt->len, pkt->buf,
> 			       pkt->len);
> 			last_pkt->len += pkt->len;
> 			free_pkt = true;
> +			last_pkt->hdr.flags |= pkt->hdr.flags;
> 			goto out;
> 		}
> 	}
> @@ -1151,6 +1163,12 @@ virtio_transport_recv_listen(struct sock *sk, struct virtio_vsock_pkt *pkt,
> 	return 0;
> }
>
> +static bool virtio_transport_valid_type(u16 type)
> +{
> +	return (type == VIRTIO_VSOCK_TYPE_STREAM) ||
> +	       (type == VIRTIO_VSOCK_TYPE_SEQPACKET);
> +}
> +
> /* We are under the virtio-vsock's vsock->rx_lock or vhost-vsock's vq->mutex
>  * lock.
>  */
> @@ -1176,7 +1194,7 @@ void virtio_transport_recv_pkt(struct virtio_transport *t,
> 					le32_to_cpu(pkt->hdr.buf_alloc),
> 					le32_to_cpu(pkt->hdr.fwd_cnt));
>
> -	if (le16_to_cpu(pkt->hdr.type) != VIRTIO_VSOCK_TYPE_STREAM) {
> +	if (!virtio_transport_valid_type(le16_to_cpu(pkt->hdr.type))) {
> 		(void)virtio_transport_reset_no_sock(t, pkt);
> 		goto free_pkt;
> 	}
> @@ -1193,6 +1211,12 @@ void virtio_transport_recv_pkt(struct virtio_transport *t,
> 		}
> 	}
>
> +	if (virtio_transport_get_type(sk) != le16_to_cpu(pkt->hdr.type)) {
> +		(void)virtio_transport_reset_no_sock(t, pkt);
> +		sock_put(sk);
> +		goto free_pkt;
> +	}
> +
> 	vsk = vsock_sk(sk);
>
> 	lock_sock(sk);
> --
> 2.25.1

The rest LGTM.

Stefano