[PATCH] net/packet: fix packet drop as of virtio gso

[Jianfeng Tan]

When we use raw socket as the vhost backend, a packet from virito with
gso offloading information, cannot be sent out in later validaton at
xmit path, as we did not set correct skb->protocol which is further used
for looking up the gso function.

To fix this, we set this field according to virito hdr information.

Fixes: e858fae2b0b8f4 ("virtio_net: use common code for virtio_net_hdr and skb 
GSO conversion")

Cc: sta...@vger.kernel.org
Signed-off-by: Jianfeng Tan <jianfeng....@linux.alibaba.com>
---
 include/linux/virtio_net.h | 18 ++++++++++++++++++
 net/packet/af_packet.c     | 11 +++++++----
 2 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
index 9397628a1967..cb462f9ab7dd 100644
--- a/include/linux/virtio_net.h
+++ b/include/linux/virtio_net.h
@@ -5,6 +5,24 @@
 #include <linux/if_vlan.h>
 #include <uapi/linux/virtio_net.h>
 
+static inline int virtio_net_hdr_set_proto(struct sk_buff *skb,
+                                          const struct virtio_net_hdr *hdr)
+{
+       switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
+       case VIRTIO_NET_HDR_GSO_TCPV4:
+       case VIRTIO_NET_HDR_GSO_UDP:
+               skb->protocol = cpu_to_be16(ETH_P_IP);
+               break;
+       case VIRTIO_NET_HDR_GSO_TCPV6:
+               skb->protocol = cpu_to_be16(ETH_P_IPV6);
+               break;
+       default:
+               return -EINVAL;
+       }
+
+       return 0;
+}
+
 static inline int virtio_net_hdr_to_skb(struct sk_buff *skb,
                                        const struct virtio_net_hdr *hdr,
                                        bool little_endian)
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 75c92a87e7b2..d6e94dc7e290 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2715,10 +2715,12 @@ static int tpacket_snd(struct packet_sock *po, struct 
msghdr *msg)
                        }
                }
 
-               if (po->has_vnet_hdr && virtio_net_hdr_to_skb(skb, vnet_hdr,
-                                                             vio_le())) {
-                       tp_len = -EINVAL;
-                       goto tpacket_error;
+               if (po->has_vnet_hdr) {
+                       if (virtio_net_hdr_to_skb(skb, vnet_hdr, vio_le())) {
+                               tp_len = -EINVAL;
+                               goto tpacket_error;
+                       }
+                       virtio_net_hdr_set_proto(skb, vnet_hdr);
                }
 
                skb->destructor = tpacket_destruct_skb;
@@ -2915,6 +2917,7 @@ static int packet_snd(struct socket *sock, struct msghdr 
*msg, size_t len)
                if (err)
                        goto out_free;
                len += sizeof(vnet_hdr);
+               virtio_net_hdr_set_proto(skb, &vnet_hdr);
        }
 
        skb_probe_transport_header(skb, reserve);
-- 
2.17.1