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5b1158e9 JK |
1 | /* (C) 1999-2001 Paul `Rusty' Russell |
2 | * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org> | |
c7232c99 | 3 | * (C) 2011 Patrick McHardy <kaber@trash.net> |
5b1158e9 JK |
4 | * |
5 | * This program is free software; you can redistribute it and/or modify | |
6 | * it under the terms of the GNU General Public License version 2 as | |
7 | * published by the Free Software Foundation. | |
8 | */ | |
c7232c99 PM |
9 | |
10 | #include <linux/module.h> | |
5b1158e9 JK |
11 | #include <linux/netfilter.h> |
12 | #include <linux/netfilter_ipv4.h> | |
c7232c99 PM |
13 | #include <linux/netfilter_ipv4/ip_tables.h> |
14 | #include <linux/ip.h> | |
5b1158e9 | 15 | #include <net/ip.h> |
5b1158e9 | 16 | |
5b1158e9 | 17 | #include <net/netfilter/nf_nat.h> |
5b1158e9 | 18 | #include <net/netfilter/nf_nat_core.h> |
c7232c99 PM |
19 | #include <net/netfilter/nf_nat_l3proto.h> |
20 | ||
21 | static const struct xt_table nf_nat_ipv4_table = { | |
22 | .name = "nat", | |
23 | .valid_hooks = (1 << NF_INET_PRE_ROUTING) | | |
24 | (1 << NF_INET_POST_ROUTING) | | |
25 | (1 << NF_INET_LOCAL_OUT) | | |
26 | (1 << NF_INET_LOCAL_IN), | |
27 | .me = THIS_MODULE, | |
28 | .af = NFPROTO_IPV4, | |
29 | }; | |
5b1158e9 | 30 | |
c7232c99 | 31 | static unsigned int alloc_null_binding(struct nf_conn *ct, unsigned int hooknum) |
5b1158e9 | 32 | { |
c7232c99 PM |
33 | /* Force range to this IP; let proto decide mapping for |
34 | * per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED). | |
35 | */ | |
36 | struct nf_nat_range range; | |
37 | ||
38 | range.flags = 0; | |
39 | pr_debug("Allocating NULL binding for %p (%pI4)\n", ct, | |
40 | HOOK2MANIP(hooknum) == NF_NAT_MANIP_SRC ? | |
41 | &ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip : | |
42 | &ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip); | |
43 | ||
44 | return nf_nat_setup_info(ct, &range, HOOK2MANIP(hooknum)); | |
45 | } | |
5b1158e9 | 46 | |
c7232c99 PM |
47 | static unsigned int nf_nat_rule_find(struct sk_buff *skb, unsigned int hooknum, |
48 | const struct net_device *in, | |
49 | const struct net_device *out, | |
50 | struct nf_conn *ct) | |
51 | { | |
52 | struct net *net = nf_ct_net(ct); | |
53 | unsigned int ret; | |
5b1158e9 | 54 | |
c7232c99 PM |
55 | ret = ipt_do_table(skb, hooknum, in, out, net->ipv4.nat_table); |
56 | if (ret == NF_ACCEPT) { | |
57 | if (!nf_nat_initialized(ct, HOOK2MANIP(hooknum))) | |
58 | ret = alloc_null_binding(ct, hooknum); | |
5b1158e9 | 59 | } |
c7232c99 | 60 | return ret; |
5b1158e9 | 61 | } |
5b1158e9 JK |
62 | |
63 | static unsigned int | |
c7232c99 PM |
64 | nf_nat_ipv4_fn(unsigned int hooknum, |
65 | struct sk_buff *skb, | |
66 | const struct net_device *in, | |
67 | const struct net_device *out, | |
68 | int (*okfn)(struct sk_buff *)) | |
5b1158e9 JK |
69 | { |
70 | struct nf_conn *ct; | |
71 | enum ip_conntrack_info ctinfo; | |
72 | struct nf_conn_nat *nat; | |
5b1158e9 JK |
73 | /* maniptype == SRC for postrouting. */ |
74 | enum nf_nat_manip_type maniptype = HOOK2MANIP(hooknum); | |
75 | ||
76 | /* We never see fragments: conntrack defrags on pre-routing | |
c7232c99 PM |
77 | * and local-out, and nf_nat_out protects post-routing. |
78 | */ | |
56f8a75c | 79 | NF_CT_ASSERT(!ip_is_fragment(ip_hdr(skb))); |
5b1158e9 | 80 | |
3db05fea | 81 | ct = nf_ct_get(skb, &ctinfo); |
5b1158e9 | 82 | /* Can't track? It's not due to stress, or conntrack would |
c7232c99 PM |
83 | * have dropped it. Hence it's the user's responsibilty to |
84 | * packet filter it out, or implement conntrack/NAT for that | |
85 | * protocol. 8) --RR | |
86 | */ | |
42cf800c | 87 | if (!ct) |
5b1158e9 | 88 | return NF_ACCEPT; |
5b1158e9 JK |
89 | |
90 | /* Don't try to NAT if this packet is not conntracked */ | |
5bfddbd4 | 91 | if (nf_ct_is_untracked(ct)) |
5b1158e9 JK |
92 | return NF_ACCEPT; |
93 | ||
94 | nat = nfct_nat(ct); | |
2d59e5ca | 95 | if (!nat) { |
8c87238b PM |
96 | /* NAT module was loaded late. */ |
97 | if (nf_ct_is_confirmed(ct)) | |
98 | return NF_ACCEPT; | |
2d59e5ca YK |
99 | nat = nf_ct_ext_add(ct, NF_CT_EXT_NAT, GFP_ATOMIC); |
100 | if (nat == NULL) { | |
0d53778e | 101 | pr_debug("failed to add NAT extension\n"); |
2d59e5ca YK |
102 | return NF_ACCEPT; |
103 | } | |
104 | } | |
5b1158e9 JK |
105 | |
106 | switch (ctinfo) { | |
107 | case IP_CT_RELATED: | |
fb048833 | 108 | case IP_CT_RELATED_REPLY: |
3db05fea | 109 | if (ip_hdr(skb)->protocol == IPPROTO_ICMP) { |
c7232c99 PM |
110 | if (!nf_nat_icmp_reply_translation(skb, ct, ctinfo, |
111 | hooknum)) | |
5b1158e9 JK |
112 | return NF_DROP; |
113 | else | |
114 | return NF_ACCEPT; | |
115 | } | |
116 | /* Fall thru... (Only ICMPs can be IP_CT_IS_REPLY) */ | |
117 | case IP_CT_NEW: | |
5b1158e9 | 118 | /* Seen it before? This can happen for loopback, retrans, |
c7232c99 PM |
119 | * or local packets. |
120 | */ | |
5b1158e9 JK |
121 | if (!nf_nat_initialized(ct, maniptype)) { |
122 | unsigned int ret; | |
123 | ||
c68cd6cc | 124 | ret = nf_nat_rule_find(skb, hooknum, in, out, ct); |
22068311 | 125 | if (ret != NF_ACCEPT) |
5b1158e9 | 126 | return ret; |
c65ef8dc | 127 | } else { |
0d53778e | 128 | pr_debug("Already setup manip %s for ct %p\n", |
cbc9f2f4 | 129 | maniptype == NF_NAT_MANIP_SRC ? "SRC" : "DST", |
0d53778e | 130 | ct); |
c65ef8dc AC |
131 | if (nf_nat_oif_changed(hooknum, ctinfo, nat, out)) |
132 | goto oif_changed; | |
133 | } | |
5b1158e9 JK |
134 | break; |
135 | ||
136 | default: | |
137 | /* ESTABLISHED */ | |
138 | NF_CT_ASSERT(ctinfo == IP_CT_ESTABLISHED || | |
fb048833 | 139 | ctinfo == IP_CT_ESTABLISHED_REPLY); |
c65ef8dc AC |
140 | if (nf_nat_oif_changed(hooknum, ctinfo, nat, out)) |
141 | goto oif_changed; | |
5b1158e9 JK |
142 | } |
143 | ||
3db05fea | 144 | return nf_nat_packet(ct, ctinfo, hooknum, skb); |
c65ef8dc AC |
145 | |
146 | oif_changed: | |
147 | nf_ct_kill_acct(ct, ctinfo, skb); | |
148 | return NF_DROP; | |
5b1158e9 JK |
149 | } |
150 | ||
151 | static unsigned int | |
c7232c99 PM |
152 | nf_nat_ipv4_in(unsigned int hooknum, |
153 | struct sk_buff *skb, | |
154 | const struct net_device *in, | |
155 | const struct net_device *out, | |
156 | int (*okfn)(struct sk_buff *)) | |
5b1158e9 JK |
157 | { |
158 | unsigned int ret; | |
3db05fea | 159 | __be32 daddr = ip_hdr(skb)->daddr; |
5b1158e9 | 160 | |
c7232c99 | 161 | ret = nf_nat_ipv4_fn(hooknum, skb, in, out, okfn); |
5b1158e9 | 162 | if (ret != NF_DROP && ret != NF_STOLEN && |
adf30907 ED |
163 | daddr != ip_hdr(skb)->daddr) |
164 | skb_dst_drop(skb); | |
165 | ||
5b1158e9 JK |
166 | return ret; |
167 | } | |
168 | ||
169 | static unsigned int | |
c7232c99 PM |
170 | nf_nat_ipv4_out(unsigned int hooknum, |
171 | struct sk_buff *skb, | |
172 | const struct net_device *in, | |
173 | const struct net_device *out, | |
174 | int (*okfn)(struct sk_buff *)) | |
5b1158e9 JK |
175 | { |
176 | #ifdef CONFIG_XFRM | |
72b72949 | 177 | const struct nf_conn *ct; |
5b1158e9 JK |
178 | enum ip_conntrack_info ctinfo; |
179 | #endif | |
180 | unsigned int ret; | |
181 | ||
182 | /* root is playing with raw sockets. */ | |
3db05fea HX |
183 | if (skb->len < sizeof(struct iphdr) || |
184 | ip_hdrlen(skb) < sizeof(struct iphdr)) | |
5b1158e9 JK |
185 | return NF_ACCEPT; |
186 | ||
c7232c99 | 187 | ret = nf_nat_ipv4_fn(hooknum, skb, in, out, okfn); |
5b1158e9 JK |
188 | #ifdef CONFIG_XFRM |
189 | if (ret != NF_DROP && ret != NF_STOLEN && | |
c7232c99 | 190 | !(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) && |
3db05fea | 191 | (ct = nf_ct_get(skb, &ctinfo)) != NULL) { |
5b1158e9 JK |
192 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); |
193 | ||
3666ed1c JP |
194 | if ((ct->tuplehash[dir].tuple.src.u3.ip != |
195 | ct->tuplehash[!dir].tuple.dst.u3.ip) || | |
38fe36a2 UW |
196 | (ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMP && |
197 | ct->tuplehash[dir].tuple.src.u.all != | |
c7232c99 PM |
198 | ct->tuplehash[!dir].tuple.dst.u.all)) |
199 | if (nf_xfrm_me_harder(skb, AF_INET) < 0) | |
200 | ret = NF_DROP; | |
5b1158e9 JK |
201 | } |
202 | #endif | |
203 | return ret; | |
204 | } | |
205 | ||
206 | static unsigned int | |
c7232c99 PM |
207 | nf_nat_ipv4_local_fn(unsigned int hooknum, |
208 | struct sk_buff *skb, | |
209 | const struct net_device *in, | |
210 | const struct net_device *out, | |
211 | int (*okfn)(struct sk_buff *)) | |
5b1158e9 | 212 | { |
72b72949 | 213 | const struct nf_conn *ct; |
5b1158e9 JK |
214 | enum ip_conntrack_info ctinfo; |
215 | unsigned int ret; | |
216 | ||
217 | /* root is playing with raw sockets. */ | |
3db05fea HX |
218 | if (skb->len < sizeof(struct iphdr) || |
219 | ip_hdrlen(skb) < sizeof(struct iphdr)) | |
5b1158e9 JK |
220 | return NF_ACCEPT; |
221 | ||
c7232c99 | 222 | ret = nf_nat_ipv4_fn(hooknum, skb, in, out, okfn); |
5b1158e9 | 223 | if (ret != NF_DROP && ret != NF_STOLEN && |
3db05fea | 224 | (ct = nf_ct_get(skb, &ctinfo)) != NULL) { |
5b1158e9 JK |
225 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); |
226 | ||
227 | if (ct->tuplehash[dir].tuple.dst.u3.ip != | |
848c29fd | 228 | ct->tuplehash[!dir].tuple.src.u3.ip) { |
3db05fea | 229 | if (ip_route_me_harder(skb, RTN_UNSPEC)) |
5b1158e9 | 230 | ret = NF_DROP; |
848c29fd PM |
231 | } |
232 | #ifdef CONFIG_XFRM | |
c7232c99 | 233 | else if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) && |
38fe36a2 | 234 | ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMP && |
c7232c99 | 235 | ct->tuplehash[dir].tuple.dst.u.all != |
848c29fd | 236 | ct->tuplehash[!dir].tuple.src.u.all) |
c7232c99 | 237 | if (nf_xfrm_me_harder(skb, AF_INET) < 0) |
848c29fd PM |
238 | ret = NF_DROP; |
239 | #endif | |
5b1158e9 JK |
240 | } |
241 | return ret; | |
242 | } | |
243 | ||
c7232c99 | 244 | static struct nf_hook_ops nf_nat_ipv4_ops[] __read_mostly = { |
5b1158e9 JK |
245 | /* Before packet filtering, change destination */ |
246 | { | |
c7232c99 | 247 | .hook = nf_nat_ipv4_in, |
5b1158e9 | 248 | .owner = THIS_MODULE, |
24c232d8 | 249 | .pf = NFPROTO_IPV4, |
6e23ae2a | 250 | .hooknum = NF_INET_PRE_ROUTING, |
5b1158e9 JK |
251 | .priority = NF_IP_PRI_NAT_DST, |
252 | }, | |
253 | /* After packet filtering, change source */ | |
254 | { | |
c7232c99 | 255 | .hook = nf_nat_ipv4_out, |
5b1158e9 | 256 | .owner = THIS_MODULE, |
24c232d8 | 257 | .pf = NFPROTO_IPV4, |
6e23ae2a | 258 | .hooknum = NF_INET_POST_ROUTING, |
5b1158e9 JK |
259 | .priority = NF_IP_PRI_NAT_SRC, |
260 | }, | |
5b1158e9 JK |
261 | /* Before packet filtering, change destination */ |
262 | { | |
c7232c99 | 263 | .hook = nf_nat_ipv4_local_fn, |
5b1158e9 | 264 | .owner = THIS_MODULE, |
24c232d8 | 265 | .pf = NFPROTO_IPV4, |
6e23ae2a | 266 | .hooknum = NF_INET_LOCAL_OUT, |
5b1158e9 JK |
267 | .priority = NF_IP_PRI_NAT_DST, |
268 | }, | |
269 | /* After packet filtering, change source */ | |
270 | { | |
c7232c99 | 271 | .hook = nf_nat_ipv4_fn, |
5b1158e9 | 272 | .owner = THIS_MODULE, |
24c232d8 | 273 | .pf = NFPROTO_IPV4, |
6e23ae2a | 274 | .hooknum = NF_INET_LOCAL_IN, |
5b1158e9 JK |
275 | .priority = NF_IP_PRI_NAT_SRC, |
276 | }, | |
5b1158e9 JK |
277 | }; |
278 | ||
c7232c99 | 279 | static int __net_init iptable_nat_net_init(struct net *net) |
5b1158e9 | 280 | { |
c7232c99 PM |
281 | struct ipt_replace *repl; |
282 | ||
283 | repl = ipt_alloc_initial_table(&nf_nat_ipv4_table); | |
284 | if (repl == NULL) | |
285 | return -ENOMEM; | |
286 | net->ipv4.nat_table = ipt_register_table(net, &nf_nat_ipv4_table, repl); | |
287 | kfree(repl); | |
6229b75d | 288 | return PTR_RET(net->ipv4.nat_table); |
c7232c99 | 289 | } |
5b1158e9 | 290 | |
c7232c99 PM |
291 | static void __net_exit iptable_nat_net_exit(struct net *net) |
292 | { | |
293 | ipt_unregister_table(net, net->ipv4.nat_table); | |
294 | } | |
5b1158e9 | 295 | |
c7232c99 PM |
296 | static struct pernet_operations iptable_nat_net_ops = { |
297 | .init = iptable_nat_net_init, | |
298 | .exit = iptable_nat_net_exit, | |
299 | }; | |
5b1158e9 | 300 | |
c7232c99 PM |
301 | static int __init iptable_nat_init(void) |
302 | { | |
303 | int err; | |
304 | ||
305 | err = register_pernet_subsys(&iptable_nat_net_ops); | |
306 | if (err < 0) | |
307 | goto err1; | |
308 | ||
309 | err = nf_register_hooks(nf_nat_ipv4_ops, ARRAY_SIZE(nf_nat_ipv4_ops)); | |
310 | if (err < 0) | |
311 | goto err2; | |
312 | return 0; | |
313 | ||
314 | err2: | |
315 | unregister_pernet_subsys(&iptable_nat_net_ops); | |
316 | err1: | |
317 | return err; | |
5b1158e9 JK |
318 | } |
319 | ||
c7232c99 | 320 | static void __exit iptable_nat_exit(void) |
5b1158e9 | 321 | { |
c7232c99 PM |
322 | nf_unregister_hooks(nf_nat_ipv4_ops, ARRAY_SIZE(nf_nat_ipv4_ops)); |
323 | unregister_pernet_subsys(&iptable_nat_net_ops); | |
5b1158e9 JK |
324 | } |
325 | ||
c7232c99 PM |
326 | module_init(iptable_nat_init); |
327 | module_exit(iptable_nat_exit); | |
5b1158e9 JK |
328 | |
329 | MODULE_LICENSE("GPL"); |