netfilter: xtables: prepare for on-demand hook register

This change prepares for upcoming on-demand xtables hook registration.

We change the protoypes of the register/unregister functions.
A followup patch will then add nf_hook_register/unregister calls
to the iptables one.

Once a hook is registered packets will be picked up, so all assignments
of the form

net->ipv4.iptable_$table = new_table

have to be moved to ip(6)t_register_table, else we can see NULL
net->ipv4.iptable_$table later.

This patch doesn't change functionality; without this the actual change
simply gets too big.

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

6 files changed, 37 insertions, 30 deletions

diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index 99425cf2819b..052d7447b52e 100644
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -2071,9 +2071,10 @@ do_ip6t_get_ctl(struct sock *sk, int cmd, void __user *user, int *len)
 	return ret;
 }
 
-struct xt_table *ip6t_register_table(struct net *net,
-				     const struct xt_table *table,
-				     const struct ip6t_replace *repl)
+int ip6t_register_table(struct net *net, const struct xt_table *table,
+			const struct ip6t_replace *repl,
+			const struct nf_hook_ops *ops,
+			struct xt_table **res)
 {
 	int ret;
 	struct xt_table_info *newinfo;
@@ -2082,10 +2083,8 @@ struct xt_table *ip6t_register_table(struct net *net,
 	struct xt_table *new_table;
 
 	newinfo = xt_alloc_table_info(repl->size);
-	if (!newinfo) {
-		ret = -ENOMEM;
-		goto out;
-	}
+	if (!newinfo)
+		return -ENOMEM;
 
 	loc_cpu_entry = newinfo->entries;
 	memcpy(loc_cpu_entry, repl->entries, repl->size);
@@ -2099,15 +2098,17 @@ struct xt_table *ip6t_register_table(struct net *net,
 		ret = PTR_ERR(new_table);
 		goto out_free;
 	}
-	return new_table;
+
+	WRITE_ONCE(*res, new_table);
+	return ret;
 
 out_free:
 	xt_free_table_info(newinfo);
-out:
-	return ERR_PTR(ret);
+	return ret;
 }
 
-void ip6t_unregister_table(struct net *net, struct xt_table *table)
+void ip6t_unregister_table(struct net *net, struct xt_table *table,
+			   const struct nf_hook_ops *ops)
 {
 	struct xt_table_info *private;
 	void *loc_cpu_entry;
diff --git a/net/ipv6/netfilter/ip6table_filter.c b/net/ipv6/netfilter/ip6table_filter.c
index 8b277b983ca5..d191d54cdf50 100644
--- a/net/ipv6/netfilter/ip6table_filter.c
+++ b/net/ipv6/netfilter/ip6table_filter.c
@@ -47,6 +47,7 @@ module_param(forward, bool, 0000);
 static int __net_init ip6table_filter_net_init(struct net *net)
 {
 	struct ip6t_replace *repl;
+	int err;
 
 	repl = ip6t_alloc_initial_table(&packet_filter);
 	if (repl == NULL)
@@ -55,15 +56,15 @@ static int __net_init ip6table_filter_net_init(struct net *net)
 	((struct ip6t_standard *)repl->entries)[1].target.verdict =
 		forward ? -NF_ACCEPT - 1 : -NF_DROP - 1;
 
-	net->ipv6.ip6table_filter =
-		ip6t_register_table(net, &packet_filter, repl);
+	err = ip6t_register_table(net, &packet_filter, repl, filter_ops,
+				  &net->ipv6.ip6table_filter);
 	kfree(repl);
-	return PTR_ERR_OR_ZERO(net->ipv6.ip6table_filter);
+	return err;
 }
 
 static void __net_exit ip6table_filter_net_exit(struct net *net)
 {
-	ip6t_unregister_table(net, net->ipv6.ip6table_filter);
+	ip6t_unregister_table(net, net->ipv6.ip6table_filter, filter_ops);
 }
 
 static struct pernet_operations ip6table_filter_net_ops = {
diff --git a/net/ipv6/netfilter/ip6table_mangle.c b/net/ipv6/netfilter/ip6table_mangle.c
index abe278b07932..fe43d08284bc 100644
--- a/net/ipv6/netfilter/ip6table_mangle.c
+++ b/net/ipv6/netfilter/ip6table_mangle.c
@@ -91,19 +91,20 @@ static struct nf_hook_ops *mangle_ops __read_mostly;
 static int __net_init ip6table_mangle_net_init(struct net *net)
 {
 	struct ip6t_replace *repl;
+	int ret;
 
 	repl = ip6t_alloc_initial_table(&packet_mangler);
 	if (repl == NULL)
 		return -ENOMEM;
-	net->ipv6.ip6table_mangle =
-		ip6t_register_table(net, &packet_mangler, repl);
+	ret = ip6t_register_table(net, &packet_mangler, repl, mangle_ops,
+				  &net->ipv6.ip6table_mangle);
 	kfree(repl);
-	return PTR_ERR_OR_ZERO(net->ipv6.ip6table_mangle);
+	return ret;
 }
 
 static void __net_exit ip6table_mangle_net_exit(struct net *net)
 {
-	ip6t_unregister_table(net, net->ipv6.ip6table_mangle);
+	ip6t_unregister_table(net, net->ipv6.ip6table_mangle, mangle_ops);
 }
 
 static struct pernet_operations ip6table_mangle_net_ops = {
diff --git a/net/ipv6/netfilter/ip6table_nat.c b/net/ipv6/netfilter/ip6table_nat.c
index de2a10a565f5..7f9740e8ef47 100644
--- a/net/ipv6/netfilter/ip6table_nat.c
+++ b/net/ipv6/netfilter/ip6table_nat.c
@@ -100,18 +100,20 @@ static struct nf_hook_ops nf_nat_ipv6_ops[] __read_mostly = {
 static int __net_init ip6table_nat_net_init(struct net *net)
 {
 	struct ip6t_replace *repl;
+	int ret;
 
 	repl = ip6t_alloc_initial_table(&nf_nat_ipv6_table);
 	if (repl == NULL)
 		return -ENOMEM;
-	net->ipv6.ip6table_nat = ip6t_register_table(net, &nf_nat_ipv6_table, repl);
+	ret = ip6t_register_table(net, &nf_nat_ipv6_table, repl,
+				  nf_nat_ipv6_ops, &net->ipv6.ip6table_nat);
 	kfree(repl);
-	return PTR_ERR_OR_ZERO(net->ipv6.ip6table_nat);
+	return ret;
 }
 
 static void __net_exit ip6table_nat_net_exit(struct net *net)
 {
-	ip6t_unregister_table(net, net->ipv6.ip6table_nat);
+	ip6t_unregister_table(net, net->ipv6.ip6table_nat, nf_nat_ipv6_ops);
 }
 
 static struct pernet_operations ip6table_nat_net_ops = {
diff --git a/net/ipv6/netfilter/ip6table_raw.c b/net/ipv6/netfilter/ip6table_raw.c
index 9021963565c3..5fac433da069 100644
--- a/net/ipv6/netfilter/ip6table_raw.c
+++ b/net/ipv6/netfilter/ip6table_raw.c
@@ -30,19 +30,20 @@ static struct nf_hook_ops *rawtable_ops __read_mostly;
 static int __net_init ip6table_raw_net_init(struct net *net)
 {
 	struct ip6t_replace *repl;
+	int ret;
 
 	repl = ip6t_alloc_initial_table(&packet_raw);
 	if (repl == NULL)
 		return -ENOMEM;
-	net->ipv6.ip6table_raw =
-		ip6t_register_table(net, &packet_raw, repl);
+	ret = ip6t_register_table(net, &packet_raw, repl, rawtable_ops,
+				  &net->ipv6.ip6table_raw);
 	kfree(repl);
-	return PTR_ERR_OR_ZERO(net->ipv6.ip6table_raw);
+	return ret;
 }
 
 static void __net_exit ip6table_raw_net_exit(struct net *net)
 {
-	ip6t_unregister_table(net, net->ipv6.ip6table_raw);
+	ip6t_unregister_table(net, net->ipv6.ip6table_raw, rawtable_ops);
 }
 
 static struct pernet_operations ip6table_raw_net_ops = {
diff --git a/net/ipv6/netfilter/ip6table_security.c b/net/ipv6/netfilter/ip6table_security.c
index 0d856fedfeb0..cf587453e322 100644
--- a/net/ipv6/netfilter/ip6table_security.c
+++ b/net/ipv6/netfilter/ip6table_security.c
@@ -47,19 +47,20 @@ static struct nf_hook_ops *sectbl_ops __read_mostly;
 static int __net_init ip6table_security_net_init(struct net *net)
 {
 	struct ip6t_replace *repl;
+	int ret;
 
 	repl = ip6t_alloc_initial_table(&security_table);
 	if (repl == NULL)
 		return -ENOMEM;
-	net->ipv6.ip6table_security =
-		ip6t_register_table(net, &security_table, repl);
+	ret = ip6t_register_table(net, &security_table, repl, sectbl_ops,
+				  &net->ipv6.ip6table_security);
 	kfree(repl);
-	return PTR_ERR_OR_ZERO(net->ipv6.ip6table_security);
+	return ret;
 }
 
 static void __net_exit ip6table_security_net_exit(struct net *net)
 {
-	ip6t_unregister_table(net, net->ipv6.ip6table_security);
+	ip6t_unregister_table(net, net->ipv6.ip6table_security, sectbl_ops);
 }
 
 static struct pernet_operations ip6table_security_net_ops = {