[net PATCH] net: Reset encap_level to avoid resetting features on inner IP headers

[Alexander Duyck]

This patch corrects an oversight in which we were allowing the encap_level
value to pass from the outer headers to the inner headers.  As a result we
were incorrectly identifying UDP or GRE tunnels as also making use of ipip
or sit when the second header actually represented a tunnel encapsulated in
either a UDP or GRE tunnel which already had the features masked.

Fixes: 76443456227097179c1482 ("net: Move GSO csum into SKB_GSO_CB")
Reported-by: Tom Herbert <t...@herbertland.com>
Signed-off-by: Alexander Duyck <adu...@mirantis.com>
---
 net/ipv4/gre_offload.c |    1 +
 net/ipv4/udp_offload.c |    1 +
 2 files changed, 2 insertions(+)

diff --git a/net/ipv4/gre_offload.c b/net/ipv4/gre_offload.c
index dea0390d65bb..43a5c76742dc 100644
--- a/net/ipv4/gre_offload.c
+++ b/net/ipv4/gre_offload.c
@@ -49,6 +49,7 @@ static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
 
        /* setup inner skb. */
        skb->encapsulation = 0;
+       SKB_GSO_CB(skb)->encap_level = 0;
        __skb_pull(skb, tnl_hlen);
        skb_reset_mac_header(skb);
        skb_set_network_header(skb, skb_inner_network_offset(skb));
diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
index 5fcb93269afb..80236a9e1769 100644
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c
@@ -56,6 +56,7 @@ static struct sk_buff *__skb_udp_tunnel_segment(struct 
sk_buff *skb,
 
        /* setup inner skb. */
        skb->encapsulation = 0;
+       SKB_GSO_CB(skb)->encap_level = 0;
        __skb_pull(skb, tnl_hlen);
        skb_reset_mac_header(skb);
        skb_set_network_header(skb, skb_inner_network_offset(skb));