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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; |
5b1158e9 | 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); |
5b1158e9 JK |
131 | break; |
132 | ||
133 | default: | |
134 | /* ESTABLISHED */ | |
135 | NF_CT_ASSERT(ctinfo == IP_CT_ESTABLISHED || | |
fb048833 | 136 | ctinfo == IP_CT_ESTABLISHED_REPLY); |
5b1158e9 JK |
137 | } |
138 | ||
3db05fea | 139 | return nf_nat_packet(ct, ctinfo, hooknum, skb); |
5b1158e9 JK |
140 | } |
141 | ||
142 | static unsigned int | |
c7232c99 PM |
143 | nf_nat_ipv4_in(unsigned int hooknum, |
144 | struct sk_buff *skb, | |
145 | const struct net_device *in, | |
146 | const struct net_device *out, | |
147 | int (*okfn)(struct sk_buff *)) | |
5b1158e9 JK |
148 | { |
149 | unsigned int ret; | |
3db05fea | 150 | __be32 daddr = ip_hdr(skb)->daddr; |
5b1158e9 | 151 | |
c7232c99 | 152 | ret = nf_nat_ipv4_fn(hooknum, skb, in, out, okfn); |
5b1158e9 | 153 | if (ret != NF_DROP && ret != NF_STOLEN && |
adf30907 ED |
154 | daddr != ip_hdr(skb)->daddr) |
155 | skb_dst_drop(skb); | |
156 | ||
5b1158e9 JK |
157 | return ret; |
158 | } | |
159 | ||
160 | static unsigned int | |
c7232c99 PM |
161 | nf_nat_ipv4_out(unsigned int hooknum, |
162 | struct sk_buff *skb, | |
163 | const struct net_device *in, | |
164 | const struct net_device *out, | |
165 | int (*okfn)(struct sk_buff *)) | |
5b1158e9 JK |
166 | { |
167 | #ifdef CONFIG_XFRM | |
72b72949 | 168 | const struct nf_conn *ct; |
5b1158e9 JK |
169 | enum ip_conntrack_info ctinfo; |
170 | #endif | |
171 | unsigned int ret; | |
172 | ||
173 | /* root is playing with raw sockets. */ | |
3db05fea HX |
174 | if (skb->len < sizeof(struct iphdr) || |
175 | ip_hdrlen(skb) < sizeof(struct iphdr)) | |
5b1158e9 JK |
176 | return NF_ACCEPT; |
177 | ||
c7232c99 | 178 | ret = nf_nat_ipv4_fn(hooknum, skb, in, out, okfn); |
5b1158e9 JK |
179 | #ifdef CONFIG_XFRM |
180 | if (ret != NF_DROP && ret != NF_STOLEN && | |
c7232c99 | 181 | !(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) && |
3db05fea | 182 | (ct = nf_ct_get(skb, &ctinfo)) != NULL) { |
5b1158e9 JK |
183 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); |
184 | ||
3666ed1c JP |
185 | if ((ct->tuplehash[dir].tuple.src.u3.ip != |
186 | ct->tuplehash[!dir].tuple.dst.u3.ip) || | |
38fe36a2 UW |
187 | (ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMP && |
188 | ct->tuplehash[dir].tuple.src.u.all != | |
c7232c99 PM |
189 | ct->tuplehash[!dir].tuple.dst.u.all)) |
190 | if (nf_xfrm_me_harder(skb, AF_INET) < 0) | |
191 | ret = NF_DROP; | |
5b1158e9 JK |
192 | } |
193 | #endif | |
194 | return ret; | |
195 | } | |
196 | ||
197 | static unsigned int | |
c7232c99 PM |
198 | nf_nat_ipv4_local_fn(unsigned int hooknum, |
199 | struct sk_buff *skb, | |
200 | const struct net_device *in, | |
201 | const struct net_device *out, | |
202 | int (*okfn)(struct sk_buff *)) | |
5b1158e9 | 203 | { |
72b72949 | 204 | const struct nf_conn *ct; |
5b1158e9 JK |
205 | enum ip_conntrack_info ctinfo; |
206 | unsigned int ret; | |
207 | ||
208 | /* root is playing with raw sockets. */ | |
3db05fea HX |
209 | if (skb->len < sizeof(struct iphdr) || |
210 | ip_hdrlen(skb) < sizeof(struct iphdr)) | |
5b1158e9 JK |
211 | return NF_ACCEPT; |
212 | ||
c7232c99 | 213 | ret = nf_nat_ipv4_fn(hooknum, skb, in, out, okfn); |
5b1158e9 | 214 | if (ret != NF_DROP && ret != NF_STOLEN && |
3db05fea | 215 | (ct = nf_ct_get(skb, &ctinfo)) != NULL) { |
5b1158e9 JK |
216 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); |
217 | ||
218 | if (ct->tuplehash[dir].tuple.dst.u3.ip != | |
848c29fd | 219 | ct->tuplehash[!dir].tuple.src.u3.ip) { |
3db05fea | 220 | if (ip_route_me_harder(skb, RTN_UNSPEC)) |
5b1158e9 | 221 | ret = NF_DROP; |
848c29fd PM |
222 | } |
223 | #ifdef CONFIG_XFRM | |
c7232c99 | 224 | else if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) && |
38fe36a2 | 225 | ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMP && |
c7232c99 | 226 | ct->tuplehash[dir].tuple.dst.u.all != |
848c29fd | 227 | ct->tuplehash[!dir].tuple.src.u.all) |
c7232c99 | 228 | if (nf_xfrm_me_harder(skb, AF_INET) < 0) |
848c29fd PM |
229 | ret = NF_DROP; |
230 | #endif | |
5b1158e9 JK |
231 | } |
232 | return ret; | |
233 | } | |
234 | ||
c7232c99 | 235 | static struct nf_hook_ops nf_nat_ipv4_ops[] __read_mostly = { |
5b1158e9 JK |
236 | /* Before packet filtering, change destination */ |
237 | { | |
c7232c99 | 238 | .hook = nf_nat_ipv4_in, |
5b1158e9 | 239 | .owner = THIS_MODULE, |
24c232d8 | 240 | .pf = NFPROTO_IPV4, |
6e23ae2a | 241 | .hooknum = NF_INET_PRE_ROUTING, |
5b1158e9 JK |
242 | .priority = NF_IP_PRI_NAT_DST, |
243 | }, | |
244 | /* After packet filtering, change source */ | |
245 | { | |
c7232c99 | 246 | .hook = nf_nat_ipv4_out, |
5b1158e9 | 247 | .owner = THIS_MODULE, |
24c232d8 | 248 | .pf = NFPROTO_IPV4, |
6e23ae2a | 249 | .hooknum = NF_INET_POST_ROUTING, |
5b1158e9 JK |
250 | .priority = NF_IP_PRI_NAT_SRC, |
251 | }, | |
5b1158e9 JK |
252 | /* Before packet filtering, change destination */ |
253 | { | |
c7232c99 | 254 | .hook = nf_nat_ipv4_local_fn, |
5b1158e9 | 255 | .owner = THIS_MODULE, |
24c232d8 | 256 | .pf = NFPROTO_IPV4, |
6e23ae2a | 257 | .hooknum = NF_INET_LOCAL_OUT, |
5b1158e9 JK |
258 | .priority = NF_IP_PRI_NAT_DST, |
259 | }, | |
260 | /* After packet filtering, change source */ | |
261 | { | |
c7232c99 | 262 | .hook = nf_nat_ipv4_fn, |
5b1158e9 | 263 | .owner = THIS_MODULE, |
24c232d8 | 264 | .pf = NFPROTO_IPV4, |
6e23ae2a | 265 | .hooknum = NF_INET_LOCAL_IN, |
5b1158e9 JK |
266 | .priority = NF_IP_PRI_NAT_SRC, |
267 | }, | |
5b1158e9 JK |
268 | }; |
269 | ||
c7232c99 | 270 | static int __net_init iptable_nat_net_init(struct net *net) |
5b1158e9 | 271 | { |
c7232c99 PM |
272 | struct ipt_replace *repl; |
273 | ||
274 | repl = ipt_alloc_initial_table(&nf_nat_ipv4_table); | |
275 | if (repl == NULL) | |
276 | return -ENOMEM; | |
277 | net->ipv4.nat_table = ipt_register_table(net, &nf_nat_ipv4_table, repl); | |
278 | kfree(repl); | |
279 | if (IS_ERR(net->ipv4.nat_table)) | |
280 | return PTR_ERR(net->ipv4.nat_table); | |
281 | return 0; | |
282 | } | |
5b1158e9 | 283 | |
c7232c99 PM |
284 | static void __net_exit iptable_nat_net_exit(struct net *net) |
285 | { | |
286 | ipt_unregister_table(net, net->ipv4.nat_table); | |
287 | } | |
5b1158e9 | 288 | |
c7232c99 PM |
289 | static struct pernet_operations iptable_nat_net_ops = { |
290 | .init = iptable_nat_net_init, | |
291 | .exit = iptable_nat_net_exit, | |
292 | }; | |
5b1158e9 | 293 | |
c7232c99 PM |
294 | static int __init iptable_nat_init(void) |
295 | { | |
296 | int err; | |
297 | ||
298 | err = register_pernet_subsys(&iptable_nat_net_ops); | |
299 | if (err < 0) | |
300 | goto err1; | |
301 | ||
302 | err = nf_register_hooks(nf_nat_ipv4_ops, ARRAY_SIZE(nf_nat_ipv4_ops)); | |
303 | if (err < 0) | |
304 | goto err2; | |
305 | return 0; | |
306 | ||
307 | err2: | |
308 | unregister_pernet_subsys(&iptable_nat_net_ops); | |
309 | err1: | |
310 | return err; | |
5b1158e9 JK |
311 | } |
312 | ||
c7232c99 | 313 | static void __exit iptable_nat_exit(void) |
5b1158e9 | 314 | { |
c7232c99 PM |
315 | nf_unregister_hooks(nf_nat_ipv4_ops, ARRAY_SIZE(nf_nat_ipv4_ops)); |
316 | unregister_pernet_subsys(&iptable_nat_net_ops); | |
5b1158e9 JK |
317 | } |
318 | ||
c7232c99 PM |
319 | module_init(iptable_nat_init); |
320 | module_exit(iptable_nat_exit); | |
5b1158e9 JK |
321 | |
322 | MODULE_LICENSE("GPL"); |