ip_tunnel: Account for secondary encapsulation header in max_headroom

When adjusting max_header for the tunnel interface based on egress
device we need to account for any extra bytes in secondary encapsulation
(e.g. FOU).

Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 1 deletions

diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index 2272de90c2d4..d9c9dc4ffeaf 100644
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -759,7 +759,7 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
                 df |= (inner_iph->frag_off&htons(IP_DF));
 
         max_headroom = LL_RESERVED_SPACE(rt->dst.dev) + sizeof(struct iphdr)
-                        + rt->dst.header_len;
+                        + rt->dst.header_len + ip_encap_hlen(&tunnel->encap);
         if (max_headroom > dev->needed_headroom)
                 dev->needed_headroom = max_headroom;