path: root/net/ipv4/gre_offload.c
diff options
authorJesse Gross <>2016-03-19 09:32:01 -0700
committerDavid S. Miller <>2016-03-20 16:33:40 -0400
commitfac8e0f579695a3ecbc4d3cac369139d7f819971 (patch)
tree4509655217edeb5184839c67a48298e45ef38039 /net/ipv4/gre_offload.c
parentb8cba75bdf6a48ea4811bbefb11a94a5c7281b68 (diff)
tunnels: Don't apply GRO to multiple layers of encapsulation.
When drivers express support for TSO of encapsulated packets, they only mean that they can do it for one layer of encapsulation. Supporting additional levels would mean updating, at a minimum, more IP length fields and they are unaware of this. No encapsulation device expresses support for handling offloaded encapsulated packets, so we won't generate these types of frames in the transmit path. However, GRO doesn't have a check for multiple levels of encapsulation and will attempt to build them. UDP tunnel GRO actually does prevent this situation but it only handles multiple UDP tunnels stacked on top of each other. This generalizes that solution to prevent any kind of tunnel stacking that would cause problems. Fixes: bf5a755f ("net-gre-gro: Add GRE support to the GRO stack") Signed-off-by: Jesse Gross <> Signed-off-by: David S. Miller <>
Diffstat (limited to 'net/ipv4/gre_offload.c')
1 files changed, 5 insertions, 0 deletions
diff --git a/net/ipv4/gre_offload.c b/net/ipv4/gre_offload.c
index 540866dbd27d..dd031617160a 100644
--- a/net/ipv4/gre_offload.c
+++ b/net/ipv4/gre_offload.c
@@ -126,6 +126,11 @@ static struct sk_buff **gre_gro_receive(struct sk_buff **head,
struct packet_offload *ptype;
__be16 type;
+ if (NAPI_GRO_CB(skb)->encap_mark)
+ goto out;
+ NAPI_GRO_CB(skb)->encap_mark = 1;
off = skb_gro_offset(skb);
hlen = off + sizeof(*greh);
greh = skb_gro_header_fast(skb, off);