ipv4: fix tunneled VM traffic over hw VXLAN/GRE GSO NIC

VM to VM GSO traffic is broken if it goes through VXLAN or GRE
tunnel and the physical NIC on the host supports hardware VXLAN/GRE
GSO offload (e.g. bnx2x and next-gen mlx4).

Two issues -
(VXLAN) VM traffic has SKB_GSO_DODGY and SKB_GSO_UDP_TUNNEL with
SKB_GSO_TCP/UDP set depending on the inner protocol. GSO header
integrity check fails in udp4_ufo_fragment if inner protocol is
TCP. Also gso_segs is calculated incorrectly using skb->len that
includes tunnel header. Fix: robust check should only be applied
to the inner packet.

(VXLAN & GRE) Once GSO header integrity check passes, NULL segs
is returned and the original skb is sent to hardware. However the
tunnel header is already pulled. Fix: tunnel header needs to be
restored so that hardware can perform GSO properly on the original
packet.

Signed-off-by: Wei-Chun Chao <weichunc@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 1 deletions

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index f140048334ce..a7e4729e974b 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -2478,6 +2478,7 @@ struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb,
                                        netdev_features_t features)
 {
         struct sk_buff *segs = ERR_PTR(-EINVAL);
+        u16 mac_offset = skb->mac_header;
         int mac_len = skb->mac_len;
         int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb);
         __be16 protocol = skb->protocol;
@@ -2497,8 +2498,11 @@ struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb,
         /* segment inner packet. */
         enc_features = skb->dev->hw_enc_features & netif_skb_features(skb);
         segs = skb_mac_gso_segment(skb, enc_features);
-        if (!segs || IS_ERR(segs))
+        if (!segs || IS_ERR(segs)) {
+                skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset,
+                                     mac_len);
                 goto out;
+        }
 
         outer_hlen = skb_tnl_header_len(skb);
         skb = segs;