netfilter: nft_nat: allow to specify layer 4 protocol NAT only

stable inclusion
from stable-5.10.56
commit cbc8012902b34516cae039f12435b78be80493a3
bugzilla: 176004 https://gitee.com/openeuler/kernel/issues/I4DYZ4

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=cbc8012902b34516cae039f12435b78be80493a3

--------------------------------

[ Upstream commit a33f387e ]

nft_nat reports a bogus EAFNOSUPPORT if no layer 3 information is specified.

Fixes: d07db988 ("netfilter: nf_tables: introduce nft_validate_register_load()")
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

net/netfilter/nft_nat.c

@@ -201,7 +201,9 @@ static int nft_nat_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
 		alen = sizeof_field(struct nf_nat_range, min_addr.ip6);
 		break;
 	default:
-		return -EAFNOSUPPORT;
+		if (tb[NFTA_NAT_REG_ADDR_MIN])
+			return -EAFNOSUPPORT;
+		break;
 	}
 	priv->family = family;