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>

5 files changed, 39 insertions, 134 deletions

diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index 4332f45..dcd7825 100644
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -29,6 +29,7 @@
 #include <linux/netfilter_ipv6/ip6_tables.h>
 #include <linux/netfilter/x_tables.h>
 #include <net/netfilter/nf_log.h>
+#include "../../netfilter/xt_repldata.h"
 
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
@@ -67,6 +68,12 @@ do {								\
 #define inline
 #endif
 
+void *ip6t_alloc_initial_table(const struct xt_table *info)
+{
+	return xt_alloc_initial_table(ip6t, IP6T);
+}
+EXPORT_SYMBOL_GPL(ip6t_alloc_initial_table);
+
 /*
    We keep a set of rules for each CPU, so we can avoid write-locking
    them in the softirq when updating the counters and therefore
diff --git a/net/ipv6/netfilter/ip6table_filter.c b/net/ipv6/netfilter/ip6table_filter.c
index 6e95d06..36b72ca 100644
--- a/net/ipv6/netfilter/ip6table_filter.c
+++ b/net/ipv6/netfilter/ip6table_filter.c
@@ -21,36 +21,6 @@ MODULE_DESCRIPTION("ip6tables filter table");
 			    (1 << NF_INET_FORWARD) | \
 			    (1 << NF_INET_LOCAL_OUT))
 
-static struct
-{
-	struct ip6t_replace repl;
-	struct ip6t_standard entries[3];
-	struct ip6t_error term;
-} initial_table __net_initdata = {
-	.repl = {
-		.name = "filter",
-		.valid_hooks = FILTER_VALID_HOOKS,
-		.num_entries = 4,
-		.size = sizeof(struct ip6t_standard) * 3 + sizeof(struct ip6t_error),
-		.hook_entry = {
-			[NF_INET_LOCAL_IN] = 0,
-			[NF_INET_FORWARD] = sizeof(struct ip6t_standard),
-			[NF_INET_LOCAL_OUT] = sizeof(struct ip6t_standard) * 2
-		},
-		.underflow = {
-			[NF_INET_LOCAL_IN] = 0,
-			[NF_INET_FORWARD] = sizeof(struct ip6t_standard),
-			[NF_INET_LOCAL_OUT] = sizeof(struct ip6t_standard) * 2
-		},
-	},
-	.entries = {
-		IP6T_STANDARD_INIT(NF_ACCEPT),	/* LOCAL_IN */
-		IP6T_STANDARD_INIT(NF_ACCEPT),	/* FORWARD */
-		IP6T_STANDARD_INIT(NF_ACCEPT),	/* LOCAL_OUT */
-	},
-	.term = IP6T_ERROR_INIT,		/* ERROR */
-};
-
 static const struct xt_table packet_filter = {
 	.name		= "filter",
 	.valid_hooks	= FILTER_VALID_HOOKS,
@@ -78,9 +48,18 @@ module_param(forward, bool, 0000);
 
 static int __net_init ip6table_filter_net_init(struct net *net)
 {
-	/* Register table */
+	struct ip6t_replace *repl;
+
+	repl = ip6t_alloc_initial_table(&packet_filter);
+	if (repl == NULL)
+		return -ENOMEM;
+	/* Entry 1 is the FORWARD hook */
+	((struct ip6t_standard *)repl->entries)[1].target.verdict =
+		-forward - 1;
+
 	net->ipv6.ip6table_filter =
-		ip6t_register_table(net, &packet_filter, &initial_table.repl);
+		ip6t_register_table(net, &packet_filter, repl);
+	kfree(repl);
 	if (IS_ERR(net->ipv6.ip6table_filter))
 		return PTR_ERR(net->ipv6.ip6table_filter);
 	return 0;
@@ -105,9 +84,6 @@ static int __init ip6table_filter_init(void)
 		return -EINVAL;
 	}
 
-	/* Entry 1 is the FORWARD hook */
-	initial_table.entries[1].target.verdict = -forward - 1;
-
 	ret = register_pernet_subsys(&ip6table_filter_net_ops);
 	if (ret < 0)
 		return ret;
diff --git a/net/ipv6/netfilter/ip6table_mangle.c b/net/ipv6/netfilter/ip6table_mangle.c
index 5023ac5..dc803b7 100644
--- a/net/ipv6/netfilter/ip6table_mangle.c
+++ b/net/ipv6/netfilter/ip6table_mangle.c
@@ -21,42 +21,6 @@ MODULE_DESCRIPTION("ip6tables mangle table");
 			    (1 << NF_INET_LOCAL_OUT) | \
 			    (1 << NF_INET_POST_ROUTING))
 
-static const struct
-{
-	struct ip6t_replace repl;
-	struct ip6t_standard entries[5];
-	struct ip6t_error term;
-} initial_table __net_initdata = {
-	.repl = {
-		.name = "mangle",
-		.valid_hooks = MANGLE_VALID_HOOKS,
-		.num_entries = 6,
-		.size = sizeof(struct ip6t_standard) * 5 + sizeof(struct ip6t_error),
-		.hook_entry = {
-			[NF_INET_PRE_ROUTING] 	= 0,
-			[NF_INET_LOCAL_IN]	= sizeof(struct ip6t_standard),
-			[NF_INET_FORWARD]	= sizeof(struct ip6t_standard) * 2,
-			[NF_INET_LOCAL_OUT] 	= sizeof(struct ip6t_standard) * 3,
-			[NF_INET_POST_ROUTING]	= sizeof(struct ip6t_standard) * 4,
-		},
-		.underflow = {
-			[NF_INET_PRE_ROUTING] 	= 0,
-			[NF_INET_LOCAL_IN]	= sizeof(struct ip6t_standard),
-			[NF_INET_FORWARD]	= sizeof(struct ip6t_standard) * 2,
-			[NF_INET_LOCAL_OUT] 	= sizeof(struct ip6t_standard) * 3,
-			[NF_INET_POST_ROUTING]	= sizeof(struct ip6t_standard) * 4,
-		},
-	},
-	.entries = {
-		IP6T_STANDARD_INIT(NF_ACCEPT),	/* PRE_ROUTING */
-		IP6T_STANDARD_INIT(NF_ACCEPT),	/* LOCAL_IN */
-		IP6T_STANDARD_INIT(NF_ACCEPT),	/* FORWARD */
-		IP6T_STANDARD_INIT(NF_ACCEPT),	/* LOCAL_OUT */
-		IP6T_STANDARD_INIT(NF_ACCEPT),	/* POST_ROUTING */
-	},
-	.term = IP6T_ERROR_INIT,		/* ERROR */
-};
-
 static const struct xt_table packet_mangler = {
 	.name		= "mangle",
 	.valid_hooks	= MANGLE_VALID_HOOKS,
@@ -126,9 +90,14 @@ ip6table_mangle_hook(unsigned int hook, struct sk_buff *skb,
 static struct nf_hook_ops *mangle_ops __read_mostly;
 static int __net_init ip6table_mangle_net_init(struct net *net)
 {
-	/* Register table */
+	struct ip6t_replace *repl;
+
+	repl = ip6t_alloc_initial_table(&packet_mangler);
+	if (repl == NULL)
+		return -ENOMEM;
 	net->ipv6.ip6table_mangle =
-		ip6t_register_table(net, &packet_mangler, &initial_table.repl);
+		ip6t_register_table(net, &packet_mangler, repl);
+	kfree(repl);
 	if (IS_ERR(net->ipv6.ip6table_mangle))
 		return PTR_ERR(net->ipv6.ip6table_mangle);
 	return 0;
diff --git a/net/ipv6/netfilter/ip6table_raw.c b/net/ipv6/netfilter/ip6table_raw.c
index 3bfa695..aef31a2 100644
--- a/net/ipv6/netfilter/ip6table_raw.c
+++ b/net/ipv6/netfilter/ip6table_raw.c
@@ -8,33 +8,6 @@
 
 #define RAW_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | (1 << NF_INET_LOCAL_OUT))
 
-static const struct
-{
-	struct ip6t_replace repl;
-	struct ip6t_standard entries[2];
-	struct ip6t_error term;
-} initial_table __net_initdata = {
-	.repl = {
-		.name = "raw",
-		.valid_hooks = RAW_VALID_HOOKS,
-		.num_entries = 3,
-		.size = sizeof(struct ip6t_standard) * 2 + sizeof(struct ip6t_error),
-		.hook_entry = {
-			[NF_INET_PRE_ROUTING] = 0,
-			[NF_INET_LOCAL_OUT] = sizeof(struct ip6t_standard)
-		},
-		.underflow = {
-			[NF_INET_PRE_ROUTING] = 0,
-			[NF_INET_LOCAL_OUT] = sizeof(struct ip6t_standard)
-		},
-	},
-	.entries = {
-		IP6T_STANDARD_INIT(NF_ACCEPT),	/* PRE_ROUTING */
-		IP6T_STANDARD_INIT(NF_ACCEPT),	/* LOCAL_OUT */
-	},
-	.term = IP6T_ERROR_INIT,		/* ERROR */
-};
-
 static const struct xt_table packet_raw = {
 	.name = "raw",
 	.valid_hooks = RAW_VALID_HOOKS,
@@ -58,9 +31,14 @@ static struct nf_hook_ops *rawtable_ops __read_mostly;
 
 static int __net_init ip6table_raw_net_init(struct net *net)
 {
-	/* Register table */
+	struct ip6t_replace *repl;
+
+	repl = ip6t_alloc_initial_table(&packet_raw);
+	if (repl == NULL)
+		return -ENOMEM;
 	net->ipv6.ip6table_raw =
-		ip6t_register_table(net, &packet_raw, &initial_table.repl);
+		ip6t_register_table(net, &packet_raw, repl);
+	kfree(repl);
 	if (IS_ERR(net->ipv6.ip6table_raw))
 		return PTR_ERR(net->ipv6.ip6table_raw);
 	return 0;
diff --git a/net/ipv6/netfilter/ip6table_security.c b/net/ipv6/netfilter/ip6table_security.c
index dd2200f..0824d86 100644
--- a/net/ipv6/netfilter/ip6table_security.c
+++ b/net/ipv6/netfilter/ip6table_security.c
@@ -26,36 +26,6 @@ MODULE_DESCRIPTION("ip6tables security table, for MAC rules");
 				(1 << NF_INET_FORWARD) | \
 				(1 << NF_INET_LOCAL_OUT)
 
-static const struct
-{
-	struct ip6t_replace repl;
-	struct ip6t_standard entries[3];
-	struct ip6t_error term;
-} initial_table __net_initdata = {
-	.repl = {
-		.name = "security",
-		.valid_hooks = SECURITY_VALID_HOOKS,
-		.num_entries = 4,
-		.size = sizeof(struct ip6t_standard) * 3 + sizeof(struct ip6t_error),
-		.hook_entry = {
-			[NF_INET_LOCAL_IN] 	= 0,
-			[NF_INET_FORWARD] 	= sizeof(struct ip6t_standard),
-			[NF_INET_LOCAL_OUT] 	= sizeof(struct ip6t_standard) * 2,
-		},
-		.underflow = {
-			[NF_INET_LOCAL_IN] 	= 0,
-			[NF_INET_FORWARD] 	= sizeof(struct ip6t_standard),
-			[NF_INET_LOCAL_OUT] 	= sizeof(struct ip6t_standard) * 2,
-		},
-	},
-	.entries = {
-		IP6T_STANDARD_INIT(NF_ACCEPT),	/* LOCAL_IN */
-		IP6T_STANDARD_INIT(NF_ACCEPT),	/* FORWARD */
-		IP6T_STANDARD_INIT(NF_ACCEPT),	/* LOCAL_OUT */
-	},
-	.term = IP6T_ERROR_INIT,		/* ERROR */
-};
-
 static const struct xt_table security_table = {
 	.name		= "security",
 	.valid_hooks	= SECURITY_VALID_HOOKS,
@@ -79,9 +49,14 @@ static struct nf_hook_ops *sectbl_ops __read_mostly;
 
 static int __net_init ip6table_security_net_init(struct net *net)
 {
-	net->ipv6.ip6table_security =
-		ip6t_register_table(net, &security_table, &initial_table.repl);
+	struct ip6t_replace *repl;
 
+	repl = ip6t_alloc_initial_table(&security_table);
+	if (repl == NULL)
+		return -ENOMEM;
+	net->ipv6.ip6table_security =
+		ip6t_register_table(net, &security_table, repl);
+	kfree(repl);
 	if (IS_ERR(net->ipv6.ip6table_security))
 		return PTR_ERR(net->ipv6.ip6table_security);