5 files changed, 17 insertions, 0 deletions
diff --git a/include/linux/netfilter.h b/include/linux/netfilter.h
index ee7a9cbd8d81..85a0b0d599e6 100644
--- a/include/linux/netfilter.h
+++ b/include/linux/netfilter.h
@@ -67,6 +67,7 @@ struct nf_hook_ops {
 	struct net_device	*dev;
 	void			*priv;
 	u_int8_t		pf;
+	bool			nat_hook;
 	unsigned int		hooknum;
 	/* Hooks are ordered in ascending priority. */
 	int			priority;
diff --git a/net/ipv4/netfilter/iptable_nat.c b/net/ipv4/netfilter/iptable_nat.c
index a1a07b338ccf..0f7255cc65ee 100644
--- a/net/ipv4/netfilter/iptable_nat.c
+++ b/net/ipv4/netfilter/iptable_nat.c
@@ -72,6 +72,7 @@ static const struct nf_hook_ops nf_nat_ipv4_ops[] = {
 	{
 		.hook		= iptable_nat_ipv4_in,
 		.pf		= NFPROTO_IPV4,
+		.nat_hook	= true,
 		.hooknum	= NF_INET_PRE_ROUTING,
 		.priority	= NF_IP_PRI_NAT_DST,
 	},
@@ -79,6 +80,7 @@ static const struct nf_hook_ops nf_nat_ipv4_ops[] = {
 	{
 		.hook		= iptable_nat_ipv4_out,
 		.pf		= NFPROTO_IPV4,
+		.nat_hook	= true,
 		.hooknum	= NF_INET_POST_ROUTING,
 		.priority	= NF_IP_PRI_NAT_SRC,
 	},
@@ -86,6 +88,7 @@ static const struct nf_hook_ops nf_nat_ipv4_ops[] = {
 	{
 		.hook		= iptable_nat_ipv4_local_fn,
 		.pf		= NFPROTO_IPV4,
+		.nat_hook	= true,
 		.hooknum	= NF_INET_LOCAL_OUT,
 		.priority	= NF_IP_PRI_NAT_DST,
 	},
@@ -93,6 +96,7 @@ static const struct nf_hook_ops nf_nat_ipv4_ops[] = {
 	{
 		.hook		= iptable_nat_ipv4_fn,
 		.pf		= NFPROTO_IPV4,
+		.nat_hook	= true,
 		.hooknum	= NF_INET_LOCAL_IN,
 		.priority	= NF_IP_PRI_NAT_SRC,
 	},
diff --git a/net/ipv6/netfilter/ip6table_nat.c b/net/ipv6/netfilter/ip6table_nat.c
index 991512576c8c..47306e45a80a 100644
--- a/net/ipv6/netfilter/ip6table_nat.c
+++ b/net/ipv6/netfilter/ip6table_nat.c
@@ -74,6 +74,7 @@ static const struct nf_hook_ops nf_nat_ipv6_ops[] = {
 	{
 		.hook		= ip6table_nat_in,
 		.pf		= NFPROTO_IPV6,
+		.nat_hook	= true,
 		.hooknum	= NF_INET_PRE_ROUTING,
 		.priority	= NF_IP6_PRI_NAT_DST,
 	},
@@ -81,6 +82,7 @@ static const struct nf_hook_ops nf_nat_ipv6_ops[] = {
 	{
 		.hook		= ip6table_nat_out,
 		.pf		= NFPROTO_IPV6,
+		.nat_hook	= true,
 		.hooknum	= NF_INET_POST_ROUTING,
 		.priority	= NF_IP6_PRI_NAT_SRC,
 	},
@@ -88,12 +90,14 @@ static const struct nf_hook_ops nf_nat_ipv6_ops[] = {
 	{
 		.hook		= ip6table_nat_local_fn,
 		.pf		= NFPROTO_IPV6,
+		.nat_hook	= true,
 		.hooknum	= NF_INET_LOCAL_OUT,
 		.priority	= NF_IP6_PRI_NAT_DST,
 	},
 	/* After packet filtering, change source */
 	{
 		.hook		= ip6table_nat_fn,
+		.nat_hook	= true,
 		.pf		= NFPROTO_IPV6,
 		.hooknum	= NF_INET_LOCAL_IN,
 		.priority	= NF_IP6_PRI_NAT_SRC,
diff --git a/net/netfilter/core.c b/net/netfilter/core.c
index ed8618f4efd7..3508a5c8edbb 100644
--- a/net/netfilter/core.c
+++ b/net/netfilter/core.c
@@ -160,6 +160,12 @@ nf_hook_entries_grow(const struct nf_hook_entries *old,
 			++i;
 			continue;
 		}
+
+		if (reg->nat_hook && orig_ops[i]->nat_hook) {
+			kvfree(new);
+			return ERR_PTR(-EEXIST);
+		}
+
 		if (inserted || reg->priority > orig_ops[i]->priority) {
 			new_ops[nhooks] = (void *)orig_ops[i];
 			new->hooks[nhooks] = old->hooks[i];
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 10798b357481..838eb581b5ab 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -1400,6 +1400,8 @@ static int nf_tables_addchain(struct nft_ctx *ctx, u8 family, u8 genmask,
 				ops->hook = hookfn;
 			if (afi->hook_ops_init)
 				afi->hook_ops_init(ops, i);
+			if (basechain->type->type == NFT_CHAIN_T_NAT)
+				ops->nat_hook = true;
 		}
 
 		chain->flags |= NFT_BASE_CHAIN;