Re: [PATCH v4 3/3] VSOCK: Add virtio vsock vsockmon hooks

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Apr 13, 2017 at 05:18:11PM +0100, Stefan Hajnoczi wrote:
> From: Gerard Garcia <ggarcia@deic.uab.cat>
> 
> The virtio drivers deal with struct virtio_vsock_pkt.  Add
> virtio_transport_deliver_tap_pkt(pkt) for handing packets to the
> vsockmon device.
> 
> We call virtio_transport_deliver_tap_pkt(pkt) from
> net/vmw_vsock/virtio_transport.c and drivers/vhost/vsock.c instead of
> common code.  This is because the drivers may drop packets before
> handing them to common code - we still want to capture them.
> 
> Signed-off-by: Gerard Garcia <ggarcia@deic.uab.cat>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
> v3:
>  * Hook virtio_transport.c (guest driver), not just
>    drivers/vhost/vsock.c (host driver)
> ---
>  include/linux/virtio_vsock.h            |  1 +
>  drivers/vhost/vsock.c                   |  8 +++++
>  net/vmw_vsock/virtio_transport.c        |  3 ++
>  net/vmw_vsock/virtio_transport_common.c | 58 +++++++++++++++++++++++++++++++++
>  4 files changed, 70 insertions(+)
> 
> diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
> index 584f9a6..ab13f07 100644
> --- a/include/linux/virtio_vsock.h
> +++ b/include/linux/virtio_vsock.h
> @@ -153,5 +153,6 @@ void virtio_transport_free_pkt(struct virtio_vsock_pkt *pkt);
>  void virtio_transport_inc_tx_pkt(struct virtio_vsock_sock *vvs, struct virtio_vsock_pkt *pkt);
>  u32 virtio_transport_get_credit(struct virtio_vsock_sock *vvs, u32 wanted);
>  void virtio_transport_put_credit(struct virtio_vsock_sock *vvs, u32 credit);
> +void virtio_transport_deliver_tap_pkt(struct virtio_vsock_pkt *pkt);
>  
>  #endif /* _LINUX_VIRTIO_VSOCK_H */
> diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
> index 44eed8e..d939ac1 100644
> --- a/drivers/vhost/vsock.c
> +++ b/drivers/vhost/vsock.c
> @@ -176,6 +176,11 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
>  				restart_tx = true;
>  		}
>  
> +		/* Deliver to monitoring devices all correctly transmitted
> +		 * packets.
> +		 */
> +		virtio_transport_deliver_tap_pkt(pkt);
> +
>  		virtio_transport_free_pkt(pkt);
>  	}
>  	if (added)
> @@ -383,6 +388,9 @@ static void vhost_vsock_handle_tx_kick(struct vhost_work *work)
>  
>  		len = pkt->len;
>  
> +		/* Deliver to monitoring devices all received packets */
> +		virtio_transport_deliver_tap_pkt(pkt);
> +
>  		/* Only accept correctly addressed packets */
>  		if (le64_to_cpu(pkt->hdr.src_cid) == vsock->guest_cid)
>  			virtio_transport_recv_pkt(pkt);
> diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
> index 68675a1..9dffe02 100644
> --- a/net/vmw_vsock/virtio_transport.c
> +++ b/net/vmw_vsock/virtio_transport.c
> @@ -144,6 +144,8 @@ virtio_transport_send_pkt_work(struct work_struct *work)
>  		list_del_init(&pkt->list);
>  		spin_unlock_bh(&vsock->send_pkt_list_lock);
>  
> +		virtio_transport_deliver_tap_pkt(pkt);
> +
>  		reply = pkt->reply;
>  
>  		sg_init_one(&hdr, &pkt->hdr, sizeof(pkt->hdr));
> @@ -370,6 +372,7 @@ static void virtio_transport_rx_work(struct work_struct *work)
>  			}
>  
>  			pkt->len = len - sizeof(pkt->hdr);
> +			virtio_transport_deliver_tap_pkt(pkt);
>  			virtio_transport_recv_pkt(pkt);
>  		}
>  	} while (!virtqueue_enable_cb(vq));
> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
> index af087b4..aae60c1 100644
> --- a/net/vmw_vsock/virtio_transport_common.c
> +++ b/net/vmw_vsock/virtio_transport_common.c
> @@ -16,6 +16,7 @@
>  #include <linux/virtio_ids.h>
>  #include <linux/virtio_config.h>
>  #include <linux/virtio_vsock.h>
> +#include <uapi/linux/vsockmon.h>
>  
>  #include <net/sock.h>
>  #include <net/af_vsock.h>
> @@ -85,6 +86,63 @@ virtio_transport_alloc_pkt(struct virtio_vsock_pkt_info *info,
>  	return NULL;
>  }
>  
> +/* Packet capture */
> +void virtio_transport_deliver_tap_pkt(struct virtio_vsock_pkt *pkt)
> +{
> +	struct sk_buff *skb;
> +	struct af_vsockmon_hdr *hdr;
> +	unsigned char *t_hdr, *payload;
> +
> +	skb = alloc_skb(sizeof(*hdr) + sizeof(pkt->hdr) + pkt->len,
> +			GFP_ATOMIC);
> +	if (!skb)
> +		return; /* nevermind if we cannot capture the packet */
> +
> +	hdr = (struct af_vsockmon_hdr *)skb_put(skb, sizeof(*hdr));
> +
> +	/* pkt->hdr is little-endian so no need to byteswap here */

Comment does not seem to make sense. Drop it?

> +	hdr->src_cid = pkt->hdr.src_cid;
> +	hdr->src_port = pkt->hdr.src_port;
> +	hdr->dst_cid = pkt->hdr.dst_cid;
> +	hdr->dst_port = pkt->hdr.dst_port;
> +
> +	hdr->transport = cpu_to_le16(AF_VSOCK_TRANSPORT_VIRTIO);
> +	hdr->len = cpu_to_le16(sizeof(pkt->hdr));
> +	hdr->reserved[0] = hdr->reserved[1] = 0;
> +
> +	switch(cpu_to_le16(pkt->hdr.op)) {

I'd expect this to be le16_to_cpu.
Does this pass check build?

> +	case VIRTIO_VSOCK_OP_REQUEST:
> +	case VIRTIO_VSOCK_OP_RESPONSE:
> +		hdr->op = cpu_to_le16(AF_VSOCK_OP_CONNECT);
> +		break;
> +	case VIRTIO_VSOCK_OP_RST:
> +	case VIRTIO_VSOCK_OP_SHUTDOWN:
> +		hdr->op = cpu_to_le16(AF_VSOCK_OP_DISCONNECT);
> +		break;
> +	case VIRTIO_VSOCK_OP_RW:
> +		hdr->op = cpu_to_le16(AF_VSOCK_OP_PAYLOAD);
> +		break;
> +	case VIRTIO_VSOCK_OP_CREDIT_UPDATE:
> +	case VIRTIO_VSOCK_OP_CREDIT_REQUEST:
> +		hdr->op = cpu_to_le16(AF_VSOCK_OP_CONTROL);
> +		break;
> +	default:
> +		hdr->op = cpu_to_le16(AF_VSOCK_OP_UNKNOWN);
> +		break;
> +	}
> +
> +	t_hdr = skb_put(skb, sizeof(pkt->hdr));
> +	memcpy(t_hdr, &pkt->hdr, sizeof(pkt->hdr));
> +
> +	if (pkt->len) {
> +		payload = skb_put(skb, pkt->len);
> +		memcpy(payload, pkt->buf, pkt->len);
> +	}
> +
> +	vsock_deliver_tap(skb);
> +}
> +EXPORT_SYMBOL_GPL(virtio_transport_deliver_tap_pkt);
> +
>  static int virtio_transport_send_pkt_info(struct vsock_sock *vsk,
>  					  struct virtio_vsock_pkt_info *info)
>  {
> -- 
> 2.9.3