netfilter: xtables: generate initial table on-demand

The static initial tables are pretty large, and after the net
namespace has been instantiated, they just hang around for nothing.
This commit removes them and creates tables on-demand at runtime when
needed.

Size shrinks by 7735 bytes (x86_64).

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>

1 files changed, 11 insertions, 35 deletions

diff --git a/net/ipv4/netfilter/iptable_filter.c b/net/ipv4/netfilter/iptable_filter.c
index c14bb85db1d..c8dc9800d62 100644
--- a/net/ipv4/netfilter/iptable_filter.c
+++ b/net/ipv4/netfilter/iptable_filter.c
@@ -23,36 +23,6 @@ MODULE_DESCRIPTION("iptables filter table");
 			    (1 << NF_INET_FORWARD) | \
 			    (1 << NF_INET_LOCAL_OUT))
 
-static struct
-{
-	struct ipt_replace repl;
-	struct ipt_standard entries[3];
-	struct ipt_error term;
-} initial_table __net_initdata = {
-	.repl = {
-		.name = "filter",
-		.valid_hooks = FILTER_VALID_HOOKS,
-		.num_entries = 4,
-		.size = sizeof(struct ipt_standard) * 3 + sizeof(struct ipt_error),
-		.hook_entry = {
-			[NF_INET_LOCAL_IN] = 0,
-			[NF_INET_FORWARD] = sizeof(struct ipt_standard),
-			[NF_INET_LOCAL_OUT] = sizeof(struct ipt_standard) * 2,
-		},
-		.underflow = {
-			[NF_INET_LOCAL_IN] = 0,
-			[NF_INET_FORWARD] = sizeof(struct ipt_standard),
-			[NF_INET_LOCAL_OUT] = sizeof(struct ipt_standard) * 2,
-		},
-	},
-	.entries = {
-		IPT_STANDARD_INIT(NF_ACCEPT),	/* LOCAL_IN */
-		IPT_STANDARD_INIT(NF_ACCEPT),	/* FORWARD */
-		IPT_STANDARD_INIT(NF_ACCEPT),	/* LOCAL_OUT */
-	},
-	.term = IPT_ERROR_INIT,			/* ERROR */
-};
-
 static const struct xt_table packet_filter = {
 	.name		= "filter",
 	.valid_hooks	= FILTER_VALID_HOOKS,
@@ -86,9 +56,18 @@ module_param(forward, bool, 0000);
 
 static int __net_init iptable_filter_net_init(struct net *net)
 {
-	/* Register table */
+	struct ipt_replace *repl;
+
+	repl = ipt_alloc_initial_table(&packet_filter);
+	if (repl == NULL)
+		return -ENOMEM;
+	/* Entry 1 is the FORWARD hook */
+	((struct ipt_standard *)repl->entries)[1].target.verdict =
+		-forward - 1;
+
 	net->ipv4.iptable_filter =
-		ipt_register_table(net, &packet_filter, &initial_table.repl);
+		ipt_register_table(net, &packet_filter, repl);
+	kfree(repl);
 	if (IS_ERR(net->ipv4.iptable_filter))
 		return PTR_ERR(net->ipv4.iptable_filter);
 	return 0;
@@ -113,9 +92,6 @@ static int __init iptable_filter_init(void)
 		return -EINVAL;
 	}
 
-	/* Entry 1 is the FORWARD hook */
-	initial_table.entries[1].target.verdict = -forward - 1;
-
 	ret = register_pernet_subsys(&iptable_filter_net_ops);
 	if (ret < 0)
 		return ret;