macvtap: fix network header pointer for VLAN tagged pkts

Network header is set with offset ETH_HLEN but it is not true for VLAN
(multiple-)tagged and results in checksum issues in lower devices.

v2: leave skb->protocol untouched (thx Vlad), comment added
v3: moved after skb_probe_transport_header() call (thx Toshiaki)

Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index 3b933bb5a8d5..edd77342773a 100644
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -719,6 +719,7 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m,
         struct virtio_net_hdr vnet_hdr = { 0 };
         int vnet_hdr_len = 0;
         int copylen = 0;
+        int depth;
         bool zerocopy = false;
         size_t linear;
         ssize_t n;
@@ -804,6 +805,12 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m,
 
         skb_probe_transport_header(skb, ETH_HLEN);
 
+        /* Move network header to the right position for VLAN tagged packets */
+        if ((skb->protocol == htons(ETH_P_8021Q) ||
+             skb->protocol == htons(ETH_P_8021AD)) &&
+            __vlan_get_protocol(skb, skb->protocol, &depth) != 0)
+                skb_set_network_header(skb, depth);
+
         rcu_read_lock();
         vlan = rcu_dereference(q->vlan);
         /* copy skb_ubuf_info for callback when skb has no error */