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9
10#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11#include <linux/types.h>
12#include <linux/ip.h>
13#include <linux/netfilter.h>
14#include <linux/netfilter_ipv4.h>
15#include <linux/module.h>
16#include <linux/kmod.h>
17#include <linux/skbuff.h>
18#include <linux/proc_fs.h>
19#include <linux/slab.h>
20#include <net/checksum.h>
21#include <net/route.h>
22#include <linux/bitops.h>
23
24#include <linux/netfilter_ipv4/ip_tables.h>
25#include <net/netfilter/nf_nat.h>
26#include <net/netfilter/nf_nat_core.h>
27#include <net/netfilter/nf_nat_rule.h>
28
29#define NAT_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | \
30 (1 << NF_INET_POST_ROUTING) | \
31 (1 << NF_INET_LOCAL_OUT) | \
32 (1 << NF_INET_LOCAL_IN))
33
34static const struct xt_table nat_table = {
35 .name = "nat",
36 .valid_hooks = NAT_VALID_HOOKS,
37 .me = THIS_MODULE,
38 .af = NFPROTO_IPV4,
39};
40
41
42static unsigned int
43ipt_snat_target(struct sk_buff *skb, const struct xt_action_param *par)
44{
45 struct nf_conn *ct;
46 enum ip_conntrack_info ctinfo;
47 const struct nf_nat_multi_range_compat *mr = par->targinfo;
48
49 NF_CT_ASSERT(par->hooknum == NF_INET_POST_ROUTING ||
50 par->hooknum == NF_INET_LOCAL_IN);
51
52 ct = nf_ct_get(skb, &ctinfo);
53
54
55 NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED ||
56 ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY));
57 NF_CT_ASSERT(par->out != NULL);
58
59 return nf_nat_setup_info(ct, &mr->range[0], IP_NAT_MANIP_SRC);
60}
61
62static unsigned int
63ipt_dnat_target(struct sk_buff *skb, const struct xt_action_param *par)
64{
65 struct nf_conn *ct;
66 enum ip_conntrack_info ctinfo;
67 const struct nf_nat_multi_range_compat *mr = par->targinfo;
68
69 NF_CT_ASSERT(par->hooknum == NF_INET_PRE_ROUTING ||
70 par->hooknum == NF_INET_LOCAL_OUT);
71
72 ct = nf_ct_get(skb, &ctinfo);
73
74
75 NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED));
76
77 return nf_nat_setup_info(ct, &mr->range[0], IP_NAT_MANIP_DST);
78}
79
80static int ipt_snat_checkentry(const struct xt_tgchk_param *par)
81{
82 const struct nf_nat_multi_range_compat *mr = par->targinfo;
83
84
85 if (mr->rangesize != 1) {
86 pr_info("SNAT: multiple ranges no longer supported\n");
87 return -EINVAL;
88 }
89 return 0;
90}
91
92static int ipt_dnat_checkentry(const struct xt_tgchk_param *par)
93{
94 const struct nf_nat_multi_range_compat *mr = par->targinfo;
95
96
97 if (mr->rangesize != 1) {
98 pr_info("DNAT: multiple ranges no longer supported\n");
99 return -EINVAL;
100 }
101 return 0;
102}
103
104static unsigned int
105alloc_null_binding(struct nf_conn *ct, unsigned int hooknum)
106{
107
108
109
110 struct nf_nat_range range;
111
112 range.flags = 0;
113 pr_debug("Allocating NULL binding for %p (%pI4)\n", ct,
114 HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC ?
115 &ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip :
116 &ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip);
117
118 return nf_nat_setup_info(ct, &range, HOOK2MANIP(hooknum));
119}
120
121int nf_nat_rule_find(struct sk_buff *skb,
122 unsigned int hooknum,
123 const struct net_device *in,
124 const struct net_device *out,
125 struct nf_conn *ct)
126{
127 struct net *net = nf_ct_net(ct);
128 int ret;
129
130 ret = ipt_do_table(skb, hooknum, in, out, net->ipv4.nat_table);
131
132 if (ret == NF_ACCEPT) {
133 if (!nf_nat_initialized(ct, HOOK2MANIP(hooknum)))
134
135 ret = alloc_null_binding(ct, hooknum);
136 }
137 return ret;
138}
139
140static struct xt_target ipt_snat_reg __read_mostly = {
141 .name = "SNAT",
142 .target = ipt_snat_target,
143 .targetsize = sizeof(struct nf_nat_multi_range_compat),
144 .table = "nat",
145 .hooks = (1 << NF_INET_POST_ROUTING) | (1 << NF_INET_LOCAL_IN),
146 .checkentry = ipt_snat_checkentry,
147 .family = AF_INET,
148};
149
150static struct xt_target ipt_dnat_reg __read_mostly = {
151 .name = "DNAT",
152 .target = ipt_dnat_target,
153 .targetsize = sizeof(struct nf_nat_multi_range_compat),
154 .table = "nat",
155 .hooks = (1 << NF_INET_PRE_ROUTING) | (1 << NF_INET_LOCAL_OUT),
156 .checkentry = ipt_dnat_checkentry,
157 .family = AF_INET,
158};
159
160static int __net_init nf_nat_rule_net_init(struct net *net)
161{
162 struct ipt_replace *repl;
163
164 repl = ipt_alloc_initial_table(&nat_table);
165 if (repl == NULL)
166 return -ENOMEM;
167 net->ipv4.nat_table = ipt_register_table(net, &nat_table, repl);
168 kfree(repl);
169 if (IS_ERR(net->ipv4.nat_table))
170 return PTR_ERR(net->ipv4.nat_table);
171 return 0;
172}
173
174static void __net_exit nf_nat_rule_net_exit(struct net *net)
175{
176 ipt_unregister_table(net, net->ipv4.nat_table);
177}
178
179static struct pernet_operations nf_nat_rule_net_ops = {
180 .init = nf_nat_rule_net_init,
181 .exit = nf_nat_rule_net_exit,
182};
183
184int __init nf_nat_rule_init(void)
185{
186 int ret;
187
188 ret = register_pernet_subsys(&nf_nat_rule_net_ops);
189 if (ret != 0)
190 goto out;
191 ret = xt_register_target(&ipt_snat_reg);
192 if (ret != 0)
193 goto unregister_table;
194
195 ret = xt_register_target(&ipt_dnat_reg);
196 if (ret != 0)
197 goto unregister_snat;
198
199 return ret;
200
201 unregister_snat:
202 xt_unregister_target(&ipt_snat_reg);
203 unregister_table:
204 unregister_pernet_subsys(&nf_nat_rule_net_ops);
205 out:
206 return ret;
207}
208
209void nf_nat_rule_cleanup(void)
210{
211 xt_unregister_target(&ipt_dnat_reg);
212 xt_unregister_target(&ipt_snat_reg);
213 unregister_pernet_subsys(&nf_nat_rule_net_ops);
214}
215
