f88e6a8a50
Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
237 lines
6.1 KiB
C
237 lines
6.1 KiB
C
/* (C) 1999-2001 Paul `Rusty' Russell
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* (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
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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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/* Everything about the rules for NAT. */
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#include <linux/types.h>
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#include <linux/ip.h>
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#include <linux/netfilter.h>
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#include <linux/netfilter_ipv4.h>
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#include <linux/module.h>
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#include <linux/kmod.h>
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#include <linux/skbuff.h>
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#include <linux/proc_fs.h>
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#include <net/checksum.h>
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#include <net/route.h>
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#include <linux/bitops.h>
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#include <linux/netfilter_ipv4/ip_tables.h>
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#include <net/netfilter/nf_nat.h>
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#include <net/netfilter/nf_nat_core.h>
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#include <net/netfilter/nf_nat_rule.h>
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#define NAT_VALID_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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static struct
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{
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struct ipt_replace repl;
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struct ipt_standard entries[3];
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struct ipt_error term;
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} nat_initial_table __net_initdata = {
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.repl = {
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.name = "nat",
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.valid_hooks = NAT_VALID_HOOKS,
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.num_entries = 4,
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.size = sizeof(struct ipt_standard) * 3 + sizeof(struct ipt_error),
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.hook_entry = {
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[NF_INET_PRE_ROUTING] = 0,
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[NF_INET_POST_ROUTING] = sizeof(struct ipt_standard),
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[NF_INET_LOCAL_OUT] = sizeof(struct ipt_standard) * 2
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},
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.underflow = {
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[NF_INET_PRE_ROUTING] = 0,
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[NF_INET_POST_ROUTING] = sizeof(struct ipt_standard),
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[NF_INET_LOCAL_OUT] = sizeof(struct ipt_standard) * 2
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},
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},
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.entries = {
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IPT_STANDARD_INIT(NF_ACCEPT), /* PRE_ROUTING */
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IPT_STANDARD_INIT(NF_ACCEPT), /* POST_ROUTING */
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IPT_STANDARD_INIT(NF_ACCEPT), /* LOCAL_OUT */
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},
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.term = IPT_ERROR_INIT, /* ERROR */
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};
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static struct xt_table nat_table = {
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.name = "nat",
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.valid_hooks = NAT_VALID_HOOKS,
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.me = THIS_MODULE,
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.af = NFPROTO_IPV4,
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};
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/* Source NAT */
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static unsigned int
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ipt_snat_target(struct sk_buff *skb, const struct xt_target_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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const struct nf_nat_multi_range_compat *mr = par->targinfo;
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NF_CT_ASSERT(par->hooknum == NF_INET_POST_ROUTING);
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ct = nf_ct_get(skb, &ctinfo);
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/* Connection must be valid and new. */
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NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED ||
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ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY));
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NF_CT_ASSERT(par->out != NULL);
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return nf_nat_setup_info(ct, &mr->range[0], IP_NAT_MANIP_SRC);
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}
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static unsigned int
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ipt_dnat_target(struct sk_buff *skb, const struct xt_target_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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const struct nf_nat_multi_range_compat *mr = par->targinfo;
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NF_CT_ASSERT(par->hooknum == NF_INET_PRE_ROUTING ||
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par->hooknum == NF_INET_LOCAL_OUT);
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ct = nf_ct_get(skb, &ctinfo);
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/* Connection must be valid and new. */
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NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED));
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return nf_nat_setup_info(ct, &mr->range[0], IP_NAT_MANIP_DST);
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}
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static bool ipt_snat_checkentry(const struct xt_tgchk_param *par)
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{
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const struct nf_nat_multi_range_compat *mr = par->targinfo;
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/* Must be a valid range */
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if (mr->rangesize != 1) {
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printk("SNAT: multiple ranges no longer supported\n");
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return false;
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}
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return true;
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}
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static bool ipt_dnat_checkentry(const struct xt_tgchk_param *par)
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{
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const struct nf_nat_multi_range_compat *mr = par->targinfo;
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/* Must be a valid range */
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if (mr->rangesize != 1) {
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printk("DNAT: multiple ranges no longer supported\n");
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return false;
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}
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return true;
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}
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unsigned int
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alloc_null_binding(struct nf_conn *ct, unsigned int hooknum)
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{
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/* Force range to this IP; let proto decide mapping for
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per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED).
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Use reply in case it's already been mangled (eg local packet).
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*/
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__be32 ip
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= (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
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? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip
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: ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip);
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struct nf_nat_range range
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= { IP_NAT_RANGE_MAP_IPS, ip, ip, { 0 }, { 0 } };
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pr_debug("Allocating NULL binding for %p (%pI4)\n", ct, &ip);
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return nf_nat_setup_info(ct, &range, HOOK2MANIP(hooknum));
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}
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int nf_nat_rule_find(struct sk_buff *skb,
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unsigned int hooknum,
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const struct net_device *in,
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const struct net_device *out,
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struct nf_conn *ct)
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{
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struct net *net = nf_ct_net(ct);
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int ret;
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ret = ipt_do_table(skb, hooknum, in, out, net->ipv4.nat_table);
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if (ret == NF_ACCEPT) {
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if (!nf_nat_initialized(ct, HOOK2MANIP(hooknum)))
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/* NUL mapping */
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ret = alloc_null_binding(ct, hooknum);
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}
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return ret;
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}
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static struct xt_target ipt_snat_reg __read_mostly = {
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.name = "SNAT",
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.target = ipt_snat_target,
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.targetsize = sizeof(struct nf_nat_multi_range_compat),
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.table = "nat",
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.hooks = 1 << NF_INET_POST_ROUTING,
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.checkentry = ipt_snat_checkentry,
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.family = AF_INET,
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};
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static struct xt_target ipt_dnat_reg __read_mostly = {
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.name = "DNAT",
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.target = ipt_dnat_target,
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.targetsize = sizeof(struct nf_nat_multi_range_compat),
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.table = "nat",
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.hooks = (1 << NF_INET_PRE_ROUTING) | (1 << NF_INET_LOCAL_OUT),
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.checkentry = ipt_dnat_checkentry,
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.family = AF_INET,
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};
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static int __net_init nf_nat_rule_net_init(struct net *net)
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{
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net->ipv4.nat_table = ipt_register_table(net, &nat_table,
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&nat_initial_table.repl);
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if (IS_ERR(net->ipv4.nat_table))
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return PTR_ERR(net->ipv4.nat_table);
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return 0;
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}
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static void __net_exit nf_nat_rule_net_exit(struct net *net)
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{
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ipt_unregister_table(net->ipv4.nat_table);
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}
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static struct pernet_operations nf_nat_rule_net_ops = {
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.init = nf_nat_rule_net_init,
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.exit = nf_nat_rule_net_exit,
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};
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int __init nf_nat_rule_init(void)
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{
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int ret;
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ret = register_pernet_subsys(&nf_nat_rule_net_ops);
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if (ret != 0)
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goto out;
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ret = xt_register_target(&ipt_snat_reg);
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if (ret != 0)
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goto unregister_table;
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ret = xt_register_target(&ipt_dnat_reg);
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if (ret != 0)
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goto unregister_snat;
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return ret;
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unregister_snat:
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xt_unregister_target(&ipt_snat_reg);
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unregister_table:
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unregister_pernet_subsys(&nf_nat_rule_net_ops);
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out:
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return ret;
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}
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void nf_nat_rule_cleanup(void)
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{
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xt_unregister_target(&ipt_dnat_reg);
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xt_unregister_target(&ipt_snat_reg);
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unregister_pernet_subsys(&nf_nat_rule_net_ops);
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}
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