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+/*
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+ * (C) 2000-2001 Svenning Soerensen <svenning@post5.tele.dk>
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+ * Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
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+ *
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+ * This program is free software; you can redistribute it and/or modify
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+ * it under the terms of the GNU General Public License version 2 as
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+ * published by the Free Software Foundation.
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+ */
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+
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+#include <linux/ip.h>
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+#include <linux/kernel.h>
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+#include <linux/module.h>
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+#include <linux/netdevice.h>
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+#include <linux/ipv6.h>
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+#include <linux/netfilter.h>
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+#include <linux/netfilter_ipv4.h>
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+#include <linux/netfilter_ipv6.h>
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+#include <linux/netfilter/x_tables.h>
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+#include <net/netfilter/nf_nat.h>
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+
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+static unsigned int
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+netmap_tg6(struct sk_buff *skb, const struct xt_action_param *par)
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+{
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+ const struct nf_nat_range *range = par->targinfo;
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+ struct nf_nat_range newrange;
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+ struct nf_conn *ct;
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+ enum ip_conntrack_info ctinfo;
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+ union nf_inet_addr new_addr, netmask;
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+ unsigned int i;
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+
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+ ct = nf_ct_get(skb, &ctinfo);
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+ for (i = 0; i < ARRAY_SIZE(range->min_addr.ip6); i++)
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+ netmask.ip6[i] = ~(range->min_addr.ip6[i] ^
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+ range->max_addr.ip6[i]);
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+
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+ if (par->hooknum == NF_INET_PRE_ROUTING ||
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+ par->hooknum == NF_INET_LOCAL_OUT)
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+ new_addr.in6 = ipv6_hdr(skb)->daddr;
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+ else
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+ new_addr.in6 = ipv6_hdr(skb)->saddr;
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+
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+ for (i = 0; i < ARRAY_SIZE(new_addr.ip6); i++) {
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+ new_addr.ip6[i] &= ~netmask.ip6[i];
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+ new_addr.ip6[i] |= range->min_addr.ip6[i] &
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+ netmask.ip6[i];
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+ }
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+
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+ newrange.flags = range->flags | NF_NAT_RANGE_MAP_IPS;
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+ newrange.min_addr = new_addr;
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+ newrange.max_addr = new_addr;
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+ newrange.min_proto = range->min_proto;
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+ newrange.max_proto = range->max_proto;
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+
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+ return nf_nat_setup_info(ct, &newrange, HOOK2MANIP(par->hooknum));
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+}
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+
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+static int netmap_tg6_checkentry(const struct xt_tgchk_param *par)
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+{
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+ const struct nf_nat_range *range = par->targinfo;
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+
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+ if (!(range->flags & NF_NAT_RANGE_MAP_IPS))
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+ return -EINVAL;
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+ return 0;
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+}
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+
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+static unsigned int
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+netmap_tg4(struct sk_buff *skb, const struct xt_action_param *par)
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+{
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+ struct nf_conn *ct;
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+ enum ip_conntrack_info ctinfo;
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+ __be32 new_ip, netmask;
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+ const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
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+ struct nf_nat_range newrange;
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+
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+ NF_CT_ASSERT(par->hooknum == NF_INET_PRE_ROUTING ||
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+ par->hooknum == NF_INET_POST_ROUTING ||
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+ par->hooknum == NF_INET_LOCAL_OUT ||
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+ par->hooknum == NF_INET_LOCAL_IN);
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+ ct = nf_ct_get(skb, &ctinfo);
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+
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+ netmask = ~(mr->range[0].min_ip ^ mr->range[0].max_ip);
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+
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+ if (par->hooknum == NF_INET_PRE_ROUTING ||
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+ par->hooknum == NF_INET_LOCAL_OUT)
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+ new_ip = ip_hdr(skb)->daddr & ~netmask;
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+ else
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+ new_ip = ip_hdr(skb)->saddr & ~netmask;
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+ new_ip |= mr->range[0].min_ip & netmask;
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+
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+ memset(&newrange.min_addr, 0, sizeof(newrange.min_addr));
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+ memset(&newrange.max_addr, 0, sizeof(newrange.max_addr));
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+ newrange.flags = mr->range[0].flags | NF_NAT_RANGE_MAP_IPS;
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+ newrange.min_addr.ip = new_ip;
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+ newrange.max_addr.ip = new_ip;
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+ newrange.min_proto = mr->range[0].min;
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+ newrange.max_proto = mr->range[0].max;
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+
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+ /* Hand modified range to generic setup. */
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+ return nf_nat_setup_info(ct, &newrange, HOOK2MANIP(par->hooknum));
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+}
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+
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+static int netmap_tg4_check(const struct xt_tgchk_param *par)
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+{
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+ const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
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+
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+ if (!(mr->range[0].flags & NF_NAT_RANGE_MAP_IPS)) {
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+ pr_debug("bad MAP_IPS.\n");
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+ return -EINVAL;
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+ }
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+ if (mr->rangesize != 1) {
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+ pr_debug("bad rangesize %u.\n", mr->rangesize);
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+ return -EINVAL;
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+ }
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+ return 0;
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+}
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+
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+static struct xt_target netmap_tg_reg[] __read_mostly = {
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+ {
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+ .name = "NETMAP",
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+ .family = NFPROTO_IPV6,
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+ .revision = 0,
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+ .target = netmap_tg6,
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+ .targetsize = sizeof(struct nf_nat_range),
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+ .table = "nat",
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+ .hooks = (1 << NF_INET_PRE_ROUTING) |
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+ (1 << NF_INET_POST_ROUTING) |
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+ (1 << NF_INET_LOCAL_OUT) |
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+ (1 << NF_INET_LOCAL_IN),
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+ .checkentry = netmap_tg6_checkentry,
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+ .me = THIS_MODULE,
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+ },
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+ {
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+ .name = "NETMAP",
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+ .family = NFPROTO_IPV4,
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+ .revision = 0,
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+ .target = netmap_tg4,
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+ .targetsize = sizeof(struct nf_nat_ipv4_multi_range_compat),
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+ .table = "nat",
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+ .hooks = (1 << NF_INET_PRE_ROUTING) |
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+ (1 << NF_INET_POST_ROUTING) |
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+ (1 << NF_INET_LOCAL_OUT) |
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+ (1 << NF_INET_LOCAL_IN),
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+ .checkentry = netmap_tg4_check,
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+ .me = THIS_MODULE,
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+ },
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+};
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+
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+static int __init netmap_tg_init(void)
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+{
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+ return xt_register_targets(netmap_tg_reg, ARRAY_SIZE(netmap_tg_reg));
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+}
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+
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+static void netmap_tg_exit(void)
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+{
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+ xt_unregister_targets(netmap_tg_reg, ARRAY_SIZE(netmap_tg_reg));
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+}
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+
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+module_init(netmap_tg_init);
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+module_exit(netmap_tg_exit);
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+
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+MODULE_LICENSE("GPL");
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+MODULE_DESCRIPTION("Xtables: 1:1 NAT mapping of subnets");
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+MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
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+MODULE_ALIAS("ip6t_NETMAP");
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+MODULE_ALIAS("ipt_NETMAP");
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Jan Engelhardt