netfilter: nat: add inet family nat support

We need minimal support from the nat core for this, as we do not
want to register additional base hooks.

When an inet hook is registered, interally register ipv4 and ipv6
hooks for them and unregister those when inet hooks are removed.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 56 insertions, 2 deletions

diff --git a/net/netfilter/nft_nat.c b/net/netfilter/nft_nat.c
index e93aed9bda88..d90d421826aa 100644
--- a/net/netfilter/nft_nat.c
+++ b/net/netfilter/nft_nat.c
@@ -140,7 +140,7 @@ static int nft_nat_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
 		return -EINVAL;
 
 	family = ntohl(nla_get_be32(tb[NFTA_NAT_FAMILY]));
-	if (family != ctx->family)
+	if (ctx->family != NFPROTO_INET && ctx->family != family)
 		return -EOPNOTSUPP;
 
 	switch (family) {
@@ -278,13 +278,67 @@ static struct nft_expr_type nft_nat_type __read_mostly = {
 	.owner          = THIS_MODULE,
 };
 
+#ifdef CONFIG_NF_TABLES_INET
+static void nft_nat_inet_eval(const struct nft_expr *expr,
+			      struct nft_regs *regs,
+			      const struct nft_pktinfo *pkt)
+{
+	const struct nft_nat *priv = nft_expr_priv(expr);
+
+	if (priv->family == nft_pf(pkt))
+		nft_nat_eval(expr, regs, pkt);
+}
+
+static const struct nft_expr_ops nft_nat_inet_ops = {
+	.type           = &nft_nat_type,
+	.size           = NFT_EXPR_SIZE(sizeof(struct nft_nat)),
+	.eval           = nft_nat_inet_eval,
+	.init           = nft_nat_init,
+	.destroy        = nft_nat_destroy,
+	.dump           = nft_nat_dump,
+	.validate	= nft_nat_validate,
+};
+
+static struct nft_expr_type nft_inet_nat_type __read_mostly = {
+	.name           = "nat",
+	.family		= NFPROTO_INET,
+	.ops            = &nft_nat_inet_ops,
+	.policy         = nft_nat_policy,
+	.maxattr        = NFTA_NAT_MAX,
+	.owner          = THIS_MODULE,
+};
+
+static int nft_nat_inet_module_init(void)
+{
+	return nft_register_expr(&nft_inet_nat_type);
+}
+
+static void nft_nat_inet_module_exit(void)
+{
+	nft_unregister_expr(&nft_inet_nat_type);
+}
+#else
+static int nft_nat_inet_module_init(void) { return 0; }
+static void nft_nat_inet_module_exit(void) { }
+#endif
+
 static int __init nft_nat_module_init(void)
 {
-	return nft_register_expr(&nft_nat_type);
+	int ret = nft_nat_inet_module_init();
+
+	if (ret)
+		return ret;
+
+	ret = nft_register_expr(&nft_nat_type);
+	if (ret)
+		nft_nat_inet_module_exit();
+
+	return ret;
 }
 
 static void __exit nft_nat_module_exit(void)
 {
+	nft_nat_inet_module_exit();
 	nft_unregister_expr(&nft_nat_type);
 }