gue: TX support for using remote checksum offload option

Add if_tunnel flag TUNNEL_ENCAP_FLAG_REMCSUM to configure
remote checksum offload on an IP tunnel. Add logic in gue_build_header
to insert remote checksum offload option.

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

1 files changed, 13 insertions, 1 deletions

diff --git a/include/net/fou.h b/include/net/fou.h
index cf4ce8874f92..25b26ffcf1df 100644
--- a/include/net/fou.h
+++ b/include/net/fou.h
@@ -20,7 +20,19 @@ static size_t fou_encap_hlen(struct ip_tunnel_encap *e)
 
 static size_t gue_encap_hlen(struct ip_tunnel_encap *e)
 {
-        return sizeof(struct udphdr) + sizeof(struct guehdr);
+        size_t len;
+        bool need_priv = false;
+
+        len = sizeof(struct udphdr) + sizeof(struct guehdr);
+
+        if (e->flags & TUNNEL_ENCAP_FLAG_REMCSUM) {
+                len += GUE_PLEN_REMCSUM;
+                need_priv = true;
+        }
+
+        len += need_priv ? GUE_LEN_PRIV : 0;
+
+        return len;
 }
 
 #endif