netfilter: combine ipt_NETMAP and ip6t_NETMAP

Combine more modules since the actual code is so small anyway that the
kmod metadata and the module in its loaded state totally outweighs the
combined actual code size.

IP_NF_TARGET_NETMAP becomes a compat option; IP6_NF_TARGET_NETMAP
is completely eliminated since it has not see a release yet.

Signed-off-by: Jan Engelhardt <jengelh@inai.de>
Acked-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

3 files changed, 176 insertions, 0 deletions

diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index 3f4b3b4a7762..ad0e0da62ede 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -648,6 +648,16 @@ config NETFILTER_XT_TARGET_MARK
 	(e.g. when running oldconfig). It selects
 	CONFIG_NETFILTER_XT_MARK (combined mark/MARK module).
 
+config NETFILTER_XT_TARGET_NETMAP
+	tristate '"NETMAP" target support'
+	depends on NF_NAT
+	---help---
+	NETMAP is an implementation of static 1:1 NAT mapping of network
+	addresses. It maps the network address part, while keeping the host
+	address part intact.
+
+	To compile it as a module, choose M here. If unsure, say N.
+
 config NETFILTER_XT_TARGET_NFLOG
 	tristate '"NFLOG" target support'
 	default m if NETFILTER_ADVANCED=n
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index 0baa3f104fcb..600d28ba514c 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -83,6 +83,7 @@ obj-$(CONFIG_NETFILTER_XT_TARGET_HL) += xt_HL.o
 obj-$(CONFIG_NETFILTER_XT_TARGET_HMARK) += xt_HMARK.o
 obj-$(CONFIG_NETFILTER_XT_TARGET_LED) += xt_LED.o
 obj-$(CONFIG_NETFILTER_XT_TARGET_LOG) += xt_LOG.o
+obj-$(CONFIG_NETFILTER_XT_TARGET_NETMAP) += xt_NETMAP.o
 obj-$(CONFIG_NETFILTER_XT_TARGET_NFLOG) += xt_NFLOG.o
 obj-$(CONFIG_NETFILTER_XT_TARGET_NFQUEUE) += xt_NFQUEUE.o
 obj-$(CONFIG_NETFILTER_XT_TARGET_RATEEST) += xt_RATEEST.o
diff --git a/net/netfilter/xt_NETMAP.c b/net/netfilter/xt_NETMAP.c
new file mode 100644
index 000000000000..b253e07cb1c5
--- /dev/null
+++ b/net/netfilter/xt_NETMAP.c
@@ -0,0 +1,165 @@
+/*
+ * (C) 2000-2001 Svenning Soerensen <svenning@post5.tele.dk>
+ * Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/ip.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/ipv6.h>
+#include <linux/netfilter.h>
+#include <linux/netfilter_ipv4.h>
+#include <linux/netfilter_ipv6.h>
+#include <linux/netfilter/x_tables.h>
+#include <net/netfilter/nf_nat.h>
+
+static unsigned int
+netmap_tg6(struct sk_buff *skb, const struct xt_action_param *par)
+{
+	const struct nf_nat_range *range = par->targinfo;
+	struct nf_nat_range newrange;
+	struct nf_conn *ct;
+	enum ip_conntrack_info ctinfo;
+	union nf_inet_addr new_addr, netmask;
+	unsigned int i;
+
+	ct = nf_ct_get(skb, &ctinfo);
+	for (i = 0; i < ARRAY_SIZE(range->min_addr.ip6); i++)
+		netmask.ip6[i] = ~(range->min_addr.ip6[i] ^
+				   range->max_addr.ip6[i]);
+
+	if (par->hooknum == NF_INET_PRE_ROUTING ||
+	    par->hooknum == NF_INET_LOCAL_OUT)
+		new_addr.in6 = ipv6_hdr(skb)->daddr;
+	else
+		new_addr.in6 = ipv6_hdr(skb)->saddr;
+
+	for (i = 0; i < ARRAY_SIZE(new_addr.ip6); i++) {
+		new_addr.ip6[i] &= ~netmask.ip6[i];
+		new_addr.ip6[i] |= range->min_addr.ip6[i] &
+				   netmask.ip6[i];
+	}
+
+	newrange.flags	= range->flags | NF_NAT_RANGE_MAP_IPS;
+	newrange.min_addr	= new_addr;
+	newrange.max_addr	= new_addr;
+	newrange.min_proto	= range->min_proto;
+	newrange.max_proto	= range->max_proto;
+
+	return nf_nat_setup_info(ct, &newrange, HOOK2MANIP(par->hooknum));
+}
+
+static int netmap_tg6_checkentry(const struct xt_tgchk_param *par)
+{
+	const struct nf_nat_range *range = par->targinfo;
+
+	if (!(range->flags & NF_NAT_RANGE_MAP_IPS))
+		return -EINVAL;
+	return 0;
+}
+
+static unsigned int
+netmap_tg4(struct sk_buff *skb, const struct xt_action_param *par)
+{
+	struct nf_conn *ct;
+	enum ip_conntrack_info ctinfo;
+	__be32 new_ip, netmask;
+	const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
+	struct nf_nat_range newrange;
+
+	NF_CT_ASSERT(par->hooknum == NF_INET_PRE_ROUTING ||
+		     par->hooknum == NF_INET_POST_ROUTING ||
+		     par->hooknum == NF_INET_LOCAL_OUT ||
+		     par->hooknum == NF_INET_LOCAL_IN);
+	ct = nf_ct_get(skb, &ctinfo);
+
+	netmask = ~(mr->range[0].min_ip ^ mr->range[0].max_ip);
+
+	if (par->hooknum == NF_INET_PRE_ROUTING ||
+	    par->hooknum == NF_INET_LOCAL_OUT)
+		new_ip = ip_hdr(skb)->daddr & ~netmask;
+	else
+		new_ip = ip_hdr(skb)->saddr & ~netmask;
+	new_ip |= mr->range[0].min_ip & netmask;
+
+	memset(&newrange.min_addr, 0, sizeof(newrange.min_addr));
+	memset(&newrange.max_addr, 0, sizeof(newrange.max_addr));
+	newrange.flags	     = mr->range[0].flags | NF_NAT_RANGE_MAP_IPS;
+	newrange.min_addr.ip = new_ip;
+	newrange.max_addr.ip = new_ip;
+	newrange.min_proto   = mr->range[0].min;
+	newrange.max_proto   = mr->range[0].max;
+
+	/* Hand modified range to generic setup. */
+	return nf_nat_setup_info(ct, &newrange, HOOK2MANIP(par->hooknum));
+}
+
+static int netmap_tg4_check(const struct xt_tgchk_param *par)
+{
+	const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
+
+	if (!(mr->range[0].flags & NF_NAT_RANGE_MAP_IPS)) {
+		pr_debug("bad MAP_IPS.\n");
+		return -EINVAL;
+	}
+	if (mr->rangesize != 1) {
+		pr_debug("bad rangesize %u.\n", mr->rangesize);
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static struct xt_target netmap_tg_reg[] __read_mostly = {
+	{
+		.name       = "NETMAP",
+		.family     = NFPROTO_IPV6,
+		.revision   = 0,
+		.target     = netmap_tg6,
+		.targetsize = sizeof(struct nf_nat_range),
+		.table      = "nat",
+		.hooks      = (1 << NF_INET_PRE_ROUTING) |
+		              (1 << NF_INET_POST_ROUTING) |
+		              (1 << NF_INET_LOCAL_OUT) |
+		              (1 << NF_INET_LOCAL_IN),
+		.checkentry = netmap_tg6_checkentry,
+		.me         = THIS_MODULE,
+	},
+	{
+		.name       = "NETMAP",
+		.family     = NFPROTO_IPV4,
+		.revision   = 0,
+		.target     = netmap_tg4,
+		.targetsize = sizeof(struct nf_nat_ipv4_multi_range_compat),
+		.table      = "nat",
+		.hooks      = (1 << NF_INET_PRE_ROUTING) |
+		              (1 << NF_INET_POST_ROUTING) |
+		              (1 << NF_INET_LOCAL_OUT) |
+		              (1 << NF_INET_LOCAL_IN),
+		.checkentry = netmap_tg4_check,
+		.me         = THIS_MODULE,
+	},
+};
+
+static int __init netmap_tg_init(void)
+{
+	return xt_register_targets(netmap_tg_reg, ARRAY_SIZE(netmap_tg_reg));
+}
+
+static void netmap_tg_exit(void)
+{
+	xt_unregister_targets(netmap_tg_reg, ARRAY_SIZE(netmap_tg_reg));
+}
+
+module_init(netmap_tg_init);
+module_exit(netmap_tg_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Xtables: 1:1 NAT mapping of subnets");
+MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
+MODULE_ALIAS("ip6t_NETMAP");
+MODULE_ALIAS("ipt_NETMAP");