netfilter: nf_tables: add devgroup support in meta expresion

Add devgroup support to let us match device group of a packets incoming
or outgoing interface.
Signed-off-by: Ana Rey <anarey@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/uapi/linux/netfilter/nf_tables.h

@@ -573,6 +573,8 @@ enum nft_exthdr_attributes {
  * @NFT_META_BRI_OIFNAME: packet output bridge interface name
  * @NFT_META_PKTTYPE: packet type (skb->pkt_type), special handling for loopback
  * @NFT_META_CPU: cpu id through smp_processor_id()
+ * @NFT_META_IIFGROUP: packet input interface group
+ * @NFT_META_OIFGROUP: packet output interface group
  */
 enum nft_meta_keys {
 	NFT_META_LEN,
@@ -596,6 +598,8 @@ enum nft_meta_keys {
 	NFT_META_BRI_OIFNAME,
 	NFT_META_PKTTYPE,
 	NFT_META_CPU,
+	NFT_META_IIFGROUP,
+	NFT_META_OIFGROUP,
 };
 
 /**

net/netfilter/nft_meta.c

@@ -155,6 +155,16 @@ void nft_meta_get_eval(const struct nft_expr *expr,
 	case NFT_META_CPU:
 		dest->data[0] = smp_processor_id();
 		break;
+	case NFT_META_IIFGROUP:
+		if (in == NULL)
+			goto err;
+		dest->data[0] = in->group;
+		break;
+	case NFT_META_OIFGROUP:
+		if (out == NULL)
+			goto err;
+		dest->data[0] = out->group;
+		break;
 	default:
 		WARN_ON(1);
 		goto err;
@@ -228,6 +238,8 @@ int nft_meta_get_init(const struct nft_ctx *ctx,
 #endif
 	case NFT_META_PKTTYPE:
 	case NFT_META_CPU:
+	case NFT_META_IIFGROUP:
+	case NFT_META_OIFGROUP:
 		break;
 	default:
 		return -EOPNOTSUPP;