vsock/virtio: non-linear skb handling for tap

For tap device new skb is created and data from the current skb is
copied to it. This adds copying data from non-linear skb to new
the skb.

Signed-off-by: Arseniy Krasnov <avkrasnov@salutedevices.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index 3e08d52a9355bfd94cd97ff2c0abd6ea0111a527..3a48e48a99ac9b75d14836d16873dc51dd2a4aaa 100644 (file)
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -106,6 +106,27 @@ out:
        return NULL;
 }
 
+static void virtio_transport_copy_nonlinear_skb(const struct sk_buff *skb,
+                                               void *dst,
+                                               size_t len)
+{
+       struct iov_iter iov_iter = { 0 };
+       struct kvec kvec;
+       size_t to_copy;
+
+       kvec.iov_base = dst;
+       kvec.iov_len = len;
+
+       iov_iter.iter_type = ITER_KVEC;
+       iov_iter.kvec = &kvec;
+       iov_iter.nr_segs = 1;
+
+       to_copy = min_t(size_t, len, skb->len);
+
+       skb_copy_datagram_iter(skb, VIRTIO_VSOCK_SKB_CB(skb)->offset,
+                              &iov_iter, to_copy);
+}
+
 /* Packet capture */
 static struct sk_buff *virtio_transport_build_skb(void *opaque)
 {
@@ -114,7 +135,6 @@ static struct sk_buff *virtio_transport_build_skb(void *opaque)
        struct af_vsockmon_hdr *hdr;
        struct sk_buff *skb;
        size_t payload_len;
-       void *payload_buf;
 
        /* A packet could be split to fit the RX buffer, so we can retrieve
         * the payload length from the header and the buffer pointer taking
@@ -122,7 +142,6 @@ static struct sk_buff *virtio_transport_build_skb(void *opaque)
         */
        pkt_hdr = virtio_vsock_hdr(pkt);
        payload_len = pkt->len;
-       payload_buf = pkt->data;
 
        skb = alloc_skb(sizeof(*hdr) + sizeof(*pkt_hdr) + payload_len,
                        GFP_ATOMIC);
@@ -165,7 +184,13 @@ static struct sk_buff *virtio_transport_build_skb(void *opaque)
        skb_put_data(skb, pkt_hdr, sizeof(*pkt_hdr));
 
        if (payload_len) {
-               skb_put_data(skb, payload_buf, payload_len);
+               if (skb_is_nonlinear(pkt)) {
+                       void *data = skb_put(skb, payload_len);
+
+                       virtio_transport_copy_nonlinear_skb(pkt, data, payload_len);
+               } else {
+                       skb_put_data(skb, pkt->data, payload_len);
+               }
        }
 
        return skb;