netfilter: nft_nat: return EOPNOTSUPP if type or flags are not supported

Instead of EINVAL which should be used for malformed netlink messages.

Fixes: eb31628e ("netfilter: nf_tables: Add support for IPv6 NAT")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nft_nat.c

@@ -129,7 +129,7 @@ static int nft_nat_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
 		priv->type = NF_NAT_MANIP_DST;
 		break;
 	default:
-		return -EINVAL;
+		return -EOPNOTSUPP;
 	}
 
 	if (tb[NFTA_NAT_FAMILY] == NULL)
@@ -196,7 +196,7 @@ static int nft_nat_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
 	if (tb[NFTA_NAT_FLAGS]) {
 		priv->flags = ntohl(nla_get_be32(tb[NFTA_NAT_FLAGS]));
 		if (priv->flags & ~NF_NAT_RANGE_MASK)
-			return -EINVAL;
+			return -EOPNOTSUPP;
 	}
 
 	return nf_ct_netns_get(ctx->net, family);