virtio_net: reject XDP programs using header adjustment

commit 17bedab272 ("bpf: xdp: Allow head adjustment in XDP prog")
added a new XDP helper to prepend and remove data from a frame.
Make virtio_net reject programs making use of this helper until
proper support is added.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: John Fastabend <john.r.fastabend@intel.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/virtio_net.c

@@ -1715,6 +1715,11 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog)
 	u16 xdp_qp = 0, curr_qp;
 	int i, err;
 
+	if (prog && prog->xdp_adjust_head) {
+		netdev_warn(dev, "Does not support bpf_xdp_adjust_head()\n");
+		return -EOPNOTSUPP;
+	}
+
 	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO4) ||
 	    virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO6) ||
 	    virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_ECN) ||