VSOCK: Add virtio vsock vsockmon hooks

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 <[e-mail]>
Signed-off-by: Stefan Hajnoczi <[e-mail]>
Reviewed-by: Jorgen Hansen <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/vhost/vsock.c

···
 				restart_tx = true;
 		}
 
+		/* Deliver to monitoring devices all correctly transmitted
+		 * packets.
+		 */
+		virtio_transport_deliver_tap_pkt(pkt);
+
 		virtio_transport_free_pkt(pkt);
 	}
 	if (added)
···
 		}
 
 		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)

include/linux/virtio_vsock.h

···
 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 */

net/vmw_vsock/virtio_transport.c

···
 		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));
···
 			}
 
 			pkt->len = len - sizeof(pkt->hdr);
+			virtio_transport_deliver_tap_pkt(pkt);
 			virtio_transport_recv_pkt(pkt);
 		}
 	} while (!virtqueue_enable_cb(vq));

net/vmw_vsock/virtio_transport_common.c

···
 #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>
···
 	kfree(pkt);
 	return NULL;
 }
+
+/* Packet capture */
+static struct sk_buff *virtio_transport_build_skb(void *opaque)
+{
+	struct virtio_vsock_pkt *pkt = opaque;
+	unsigned char *t_hdr, *payload;
+	struct af_vsockmon_hdr *hdr;
+	struct sk_buff *skb;
+
+	skb = alloc_skb(sizeof(*hdr) + sizeof(pkt->hdr) + pkt->len,
+			GFP_ATOMIC);
+	if (!skb)
+		return NULL;
+
+	hdr = (struct af_vsockmon_hdr *)skb_put(skb, sizeof(*hdr));
+
+	/* pkt->hdr is little-endian so no need to byteswap here */
+	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));
+	memset(hdr->reserved, 0, sizeof(hdr->reserved));
+
+	switch (le16_to_cpu(pkt->hdr.op)) {
+	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);
+	}
+
+	return skb;
+}
+
+void virtio_transport_deliver_tap_pkt(struct virtio_vsock_pkt *pkt)
+{
+	vsock_deliver_tap(virtio_transport_build_skb, pkt);
+}
+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)