netfilter: nft_inner: add geneve support

Geneve tunnel header may contain options, parse geneve header and update
offset to point to the link layer header according to the opt_len field.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/uapi/linux/netfilter/nf_tables.h

@@ -783,6 +783,7 @@ enum nft_payload_csum_flags {
 enum nft_inner_type {
 	NFT_INNER_UNSPEC	= 0,
 	NFT_INNER_VXLAN,
+	NFT_INNER_GENEVE,
 };
 
 enum nft_inner_flags {

net/netfilter/nft_inner.c

@@ -17,6 +17,7 @@
 #include <linux/tcp.h>
 #include <linux/udp.h>
 #include <net/gre.h>
+#include <net/geneve.h>
 #include <net/ip.h>
 #include <linux/icmpv6.h>
 #include <linux/ip.h>
@@ -181,6 +182,22 @@ static int nft_inner_parse_tunhdr(const struct nft_inner *priv,
 	ctx->flags |= NFT_PAYLOAD_CTX_INNER_TUN;
 	*off += priv->hdrsize;
 
+	switch (priv->type) {
+	case NFT_INNER_GENEVE: {
+		struct genevehdr *gnvh, _gnvh;
+
+		gnvh = skb_header_pointer(pkt->skb, pkt->inneroff,
+					  sizeof(_gnvh), &_gnvh);
+		if (!gnvh)
+			return -1;
+
+		*off += gnvh->opt_len * 4;
+		}
+		break;
+	default:
+		break;
+	}
+
 	return 0;
 }