netfilter: nft_meta: add l4proto support

For L3-proto independant rules we need to get at the L4 protocol value
directly. Add it to the nft_pktinfo struct and use the meta expression
to retrieve it.

Signed-off-by: Patrick McHardy <[e-mail]>
Signed-off-by: Pablo Neira Ayuso <[e-mail]>

include/net/netfilter/nf_tables.h

···
 	const struct nf_hook_ops	*ops;
 	u8				nhoff;
 	u8				thoff;
+	u8				tprot;
 	/* for x_tables compatibility */
 	struct xt_action_param		xt;
 };

include/net/netfilter/nf_tables_ipv4.h

···
 
 	nft_set_pktinfo(pkt, ops, skb, in, out);
 
-	pkt->xt.thoff = ip_hdrlen(pkt->skb);
 	ip = ip_hdr(pkt->skb);
+	pkt->tprot = ip->protocol;
+	pkt->xt.thoff = ip_hdrlen(pkt->skb);
 	pkt->xt.fragoff = ntohs(ip->frag_off) & IP_OFFSET;
 }
 

include/net/netfilter/nf_tables_ipv6.h

···
 	if (protohdr < 0)
 		return -1;
 
+	pkt->tprot = protohdr;
 	pkt->xt.thoff = thoff;
 	pkt->xt.fragoff = frag_off;
 

include/uapi/linux/netfilter/nf_tables.h

···
  * @NFT_META_RTCLASSID: realm value of packet's route (skb->dst->tclassid)
  * @NFT_META_SECMARK: packet secmark (skb->secmark)
  * @NFT_META_NFPROTO: netfilter protocol
+ * @NFT_META_L4PROTO: layer 4 protocol number
  */
 enum nft_meta_keys {
 	NFT_META_LEN,
···
 	NFT_META_RTCLASSID,
 	NFT_META_SECMARK,
 	NFT_META_NFPROTO,
+	NFT_META_L4PROTO,
 };
 
 /**

net/netfilter/nft_meta.c

···
 	case NFT_META_NFPROTO:
 		dest->data[0] = pkt->ops->pf;
 		break;
+	case NFT_META_L4PROTO:
+		dest->data[0] = pkt->tprot;
+		break;
 	case NFT_META_PRIORITY:
 		dest->data[0] = skb->priority;
 		break;
···
 	case NFT_META_LEN:
 	case NFT_META_PROTOCOL:
 	case NFT_META_NFPROTO:
+	case NFT_META_L4PROTO:
 	case NFT_META_PRIORITY:
 	case NFT_META_MARK:
 	case NFT_META_IIF: