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1 | /* (C) 1999-2001 Paul `Rusty' Russell | |
2 | * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org> | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License version 2 as | |
6 | * published by the Free Software Foundation. | |
7 | */ | |
8 | ||
9 | /* Everything about the rules for NAT. */ | |
10 | #include <linux/types.h> | |
11 | #include <linux/ip.h> | |
12 | #include <linux/netfilter.h> | |
13 | #include <linux/netfilter_ipv4.h> | |
14 | #include <linux/module.h> | |
15 | #include <linux/kmod.h> | |
16 | #include <linux/skbuff.h> | |
17 | #include <linux/proc_fs.h> | |
18 | #include <net/checksum.h> | |
19 | #include <net/route.h> | |
20 | #include <linux/bitops.h> | |
21 | ||
22 | #include <linux/netfilter_ipv4/ip_tables.h> | |
23 | #include <net/netfilter/nf_nat.h> | |
24 | #include <net/netfilter/nf_nat_core.h> | |
25 | #include <net/netfilter/nf_nat_rule.h> | |
26 | ||
27 | #define NAT_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | \ | |
28 | (1 << NF_INET_POST_ROUTING) | \ | |
29 | (1 << NF_INET_LOCAL_OUT)) | |
30 | ||
31 | static const struct xt_table nat_table = { | |
32 | .name = "nat", | |
33 | .valid_hooks = NAT_VALID_HOOKS, | |
34 | .me = THIS_MODULE, | |
35 | .af = NFPROTO_IPV4, | |
36 | }; | |
37 | ||
38 | /* Source NAT */ | |
39 | static unsigned int | |
40 | ipt_snat_target(struct sk_buff *skb, const struct xt_target_param *par) | |
41 | { | |
42 | struct nf_conn *ct; | |
43 | enum ip_conntrack_info ctinfo; | |
44 | const struct nf_nat_multi_range_compat *mr = par->targinfo; | |
45 | ||
46 | NF_CT_ASSERT(par->hooknum == NF_INET_POST_ROUTING); | |
47 | ||
48 | ct = nf_ct_get(skb, &ctinfo); | |
49 | ||
50 | /* Connection must be valid and new. */ | |
51 | NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED || | |
52 | ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY)); | |
53 | NF_CT_ASSERT(par->out != NULL); | |
54 | ||
55 | return nf_nat_setup_info(ct, &mr->range[0], IP_NAT_MANIP_SRC); | |
56 | } | |
57 | ||
58 | static unsigned int | |
59 | ipt_dnat_target(struct sk_buff *skb, const struct xt_target_param *par) | |
60 | { | |
61 | struct nf_conn *ct; | |
62 | enum ip_conntrack_info ctinfo; | |
63 | const struct nf_nat_multi_range_compat *mr = par->targinfo; | |
64 | ||
65 | NF_CT_ASSERT(par->hooknum == NF_INET_PRE_ROUTING || | |
66 | par->hooknum == NF_INET_LOCAL_OUT); | |
67 | ||
68 | ct = nf_ct_get(skb, &ctinfo); | |
69 | ||
70 | /* Connection must be valid and new. */ | |
71 | NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED)); | |
72 | ||
73 | return nf_nat_setup_info(ct, &mr->range[0], IP_NAT_MANIP_DST); | |
74 | } | |
75 | ||
76 | static bool ipt_snat_checkentry(const struct xt_tgchk_param *par) | |
77 | { | |
78 | const struct nf_nat_multi_range_compat *mr = par->targinfo; | |
79 | ||
80 | /* Must be a valid range */ | |
81 | if (mr->rangesize != 1) { | |
82 | printk("SNAT: multiple ranges no longer supported\n"); | |
83 | return false; | |
84 | } | |
85 | return true; | |
86 | } | |
87 | ||
88 | static bool ipt_dnat_checkentry(const struct xt_tgchk_param *par) | |
89 | { | |
90 | const struct nf_nat_multi_range_compat *mr = par->targinfo; | |
91 | ||
92 | /* Must be a valid range */ | |
93 | if (mr->rangesize != 1) { | |
94 | printk("DNAT: multiple ranges no longer supported\n"); | |
95 | return false; | |
96 | } | |
97 | return true; | |
98 | } | |
99 | ||
100 | unsigned int | |
101 | alloc_null_binding(struct nf_conn *ct, unsigned int hooknum) | |
102 | { | |
103 | /* Force range to this IP; let proto decide mapping for | |
104 | per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED). | |
105 | Use reply in case it's already been mangled (eg local packet). | |
106 | */ | |
107 | __be32 ip | |
108 | = (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC | |
109 | ? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip | |
110 | : ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip); | |
111 | struct nf_nat_range range | |
112 | = { IP_NAT_RANGE_MAP_IPS, ip, ip, { 0 }, { 0 } }; | |
113 | ||
114 | pr_debug("Allocating NULL binding for %p (%pI4)\n", ct, &ip); | |
115 | return nf_nat_setup_info(ct, &range, HOOK2MANIP(hooknum)); | |
116 | } | |
117 | ||
118 | int nf_nat_rule_find(struct sk_buff *skb, | |
119 | unsigned int hooknum, | |
120 | const struct net_device *in, | |
121 | const struct net_device *out, | |
122 | struct nf_conn *ct) | |
123 | { | |
124 | struct net *net = nf_ct_net(ct); | |
125 | int ret; | |
126 | ||
127 | ret = ipt_do_table(skb, hooknum, in, out, net->ipv4.nat_table); | |
128 | ||
129 | if (ret == NF_ACCEPT) { | |
130 | if (!nf_nat_initialized(ct, HOOK2MANIP(hooknum))) | |
131 | /* NUL mapping */ | |
132 | ret = alloc_null_binding(ct, hooknum); | |
133 | } | |
134 | return ret; | |
135 | } | |
136 | ||
137 | static struct xt_target ipt_snat_reg __read_mostly = { | |
138 | .name = "SNAT", | |
139 | .target = ipt_snat_target, | |
140 | .targetsize = sizeof(struct nf_nat_multi_range_compat), | |
141 | .table = "nat", | |
142 | .hooks = 1 << NF_INET_POST_ROUTING, | |
143 | .checkentry = ipt_snat_checkentry, | |
144 | .family = AF_INET, | |
145 | }; | |
146 | ||
147 | static struct xt_target ipt_dnat_reg __read_mostly = { | |
148 | .name = "DNAT", | |
149 | .target = ipt_dnat_target, | |
150 | .targetsize = sizeof(struct nf_nat_multi_range_compat), | |
151 | .table = "nat", | |
152 | .hooks = (1 << NF_INET_PRE_ROUTING) | (1 << NF_INET_LOCAL_OUT), | |
153 | .checkentry = ipt_dnat_checkentry, | |
154 | .family = AF_INET, | |
155 | }; | |
156 | ||
157 | static int __net_init nf_nat_rule_net_init(struct net *net) | |
158 | { | |
159 | struct ipt_replace *repl; | |
160 | ||
161 | repl = ipt_alloc_initial_table(&nat_table); | |
162 | if (repl == NULL) | |
163 | return -ENOMEM; | |
164 | net->ipv4.nat_table = ipt_register_table(net, &nat_table, repl); | |
165 | kfree(repl); | |
166 | if (IS_ERR(net->ipv4.nat_table)) | |
167 | return PTR_ERR(net->ipv4.nat_table); | |
168 | return 0; | |
169 | } | |
170 | ||
171 | static void __net_exit nf_nat_rule_net_exit(struct net *net) | |
172 | { | |
173 | ipt_unregister_table(net, net->ipv4.nat_table); | |
174 | } | |
175 | ||
176 | static struct pernet_operations nf_nat_rule_net_ops = { | |
177 | .init = nf_nat_rule_net_init, | |
178 | .exit = nf_nat_rule_net_exit, | |
179 | }; | |
180 | ||
181 | int __init nf_nat_rule_init(void) | |
182 | { | |
183 | int ret; | |
184 | ||
185 | ret = register_pernet_subsys(&nf_nat_rule_net_ops); | |
186 | if (ret != 0) | |
187 | goto out; | |
188 | ret = xt_register_target(&ipt_snat_reg); | |
189 | if (ret != 0) | |
190 | goto unregister_table; | |
191 | ||
192 | ret = xt_register_target(&ipt_dnat_reg); | |
193 | if (ret != 0) | |
194 | goto unregister_snat; | |
195 | ||
196 | return ret; | |
197 | ||
198 | unregister_snat: | |
199 | xt_unregister_target(&ipt_snat_reg); | |
200 | unregister_table: | |
201 | unregister_pernet_subsys(&nf_nat_rule_net_ops); | |
202 | out: | |
203 | return ret; | |
204 | } | |
205 | ||
206 | void nf_nat_rule_cleanup(void) | |
207 | { | |
208 | xt_unregister_target(&ipt_dnat_reg); | |
209 | xt_unregister_target(&ipt_snat_reg); | |
210 | unregister_pernet_subsys(&nf_nat_rule_net_ops); | |
211 | } |