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

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Date:   Thu, 3 Jun 2021 16:56:23 +0200
From:   Stefano Garzarella <sgarzare@...hat.com>
To:     Arseny Krasnov <arseny.krasnov@...persky.com>
Cc:     Stefan Hajnoczi <stefanha@...hat.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Jorgen Hansen <jhansen@...are.com>,
        Andra Paraschiv <andraprs@...zon.com>,
        Colin Ian King <colin.king@...onical.com>,
        Norbert Slusarek <nslusarek@....net>, kvm@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, oxffffaa@...il.com
Subject: Re: [PATCH v10 12/18] virtio/vsock: add SEQPACKET receive logic

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@...persky.com>
>---
> 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