Commit | Line | Data |
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b4219952 HX |
1 | /* |
2 | * Stateless NAT actions | |
3 | * | |
4 | * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au> | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify it | |
7 | * under the terms of the GNU General Public License as published by the Free | |
8 | * Software Foundation; either version 2 of the License, or (at your option) | |
9 | * any later version. | |
10 | */ | |
11 | ||
12 | #include <linux/errno.h> | |
13 | #include <linux/init.h> | |
14 | #include <linux/kernel.h> | |
15 | #include <linux/module.h> | |
16 | #include <linux/netfilter.h> | |
17 | #include <linux/rtnetlink.h> | |
18 | #include <linux/skbuff.h> | |
19 | #include <linux/slab.h> | |
20 | #include <linux/spinlock.h> | |
21 | #include <linux/string.h> | |
22 | #include <linux/tc_act/tc_nat.h> | |
23 | #include <net/act_api.h> | |
24 | #include <net/icmp.h> | |
25 | #include <net/ip.h> | |
26 | #include <net/netlink.h> | |
27 | #include <net/tc_act/tc_nat.h> | |
28 | #include <net/tcp.h> | |
29 | #include <net/udp.h> | |
30 | ||
31 | ||
32 | #define NAT_TAB_MASK 15 | |
b4219952 | 33 | |
ddf97ccd WC |
34 | static int nat_net_id; |
35 | ||
53b2bf3f PM |
36 | static const struct nla_policy nat_policy[TCA_NAT_MAX + 1] = { |
37 | [TCA_NAT_PARMS] = { .len = sizeof(struct tc_nat) }, | |
38 | }; | |
39 | ||
c1b52739 | 40 | static int tcf_nat_init(struct net *net, struct nlattr *nla, struct nlattr *est, |
b4219952 HX |
41 | struct tc_action *a, int ovr, int bind) |
42 | { | |
ddf97ccd | 43 | struct tc_action_net *tn = net_generic(net, nat_net_id); |
7ba699c6 | 44 | struct nlattr *tb[TCA_NAT_MAX + 1]; |
b4219952 | 45 | struct tc_nat *parm; |
cee63723 | 46 | int ret = 0, err; |
b4219952 | 47 | struct tcf_nat *p; |
b4219952 | 48 | |
cee63723 | 49 | if (nla == NULL) |
b4219952 HX |
50 | return -EINVAL; |
51 | ||
53b2bf3f | 52 | err = nla_parse_nested(tb, TCA_NAT_MAX, nla, nat_policy); |
cee63723 PM |
53 | if (err < 0) |
54 | return err; | |
55 | ||
53b2bf3f | 56 | if (tb[TCA_NAT_PARMS] == NULL) |
b4219952 | 57 | return -EINVAL; |
7ba699c6 | 58 | parm = nla_data(tb[TCA_NAT_PARMS]); |
b4219952 | 59 | |
ddf97ccd WC |
60 | if (!tcf_hash_check(tn, parm->index, a, bind)) { |
61 | ret = tcf_hash_create(tn, parm->index, est, a, | |
62 | sizeof(*p), bind, false); | |
86062033 WC |
63 | if (ret) |
64 | return ret; | |
b4219952 HX |
65 | ret = ACT_P_CREATED; |
66 | } else { | |
1a29321e JHS |
67 | if (bind) |
68 | return 0; | |
86062033 | 69 | tcf_hash_release(a, bind); |
1a29321e | 70 | if (!ovr) |
b4219952 | 71 | return -EEXIST; |
b4219952 | 72 | } |
86062033 | 73 | p = to_tcf_nat(a); |
b4219952 HX |
74 | |
75 | spin_lock_bh(&p->tcf_lock); | |
76 | p->old_addr = parm->old_addr; | |
77 | p->new_addr = parm->new_addr; | |
78 | p->mask = parm->mask; | |
79 | p->flags = parm->flags; | |
80 | ||
81 | p->tcf_action = parm->action; | |
82 | spin_unlock_bh(&p->tcf_lock); | |
83 | ||
84 | if (ret == ACT_P_CREATED) | |
ddf97ccd | 85 | tcf_hash_insert(tn, a); |
b4219952 HX |
86 | |
87 | return ret; | |
88 | } | |
89 | ||
dc7f9f6e | 90 | static int tcf_nat(struct sk_buff *skb, const struct tc_action *a, |
b4219952 HX |
91 | struct tcf_result *res) |
92 | { | |
93 | struct tcf_nat *p = a->priv; | |
94 | struct iphdr *iph; | |
95 | __be32 old_addr; | |
96 | __be32 new_addr; | |
97 | __be32 mask; | |
98 | __be32 addr; | |
99 | int egress; | |
100 | int action; | |
101 | int ihl; | |
36d12690 | 102 | int noff; |
b4219952 HX |
103 | |
104 | spin_lock(&p->tcf_lock); | |
105 | ||
106 | p->tcf_tm.lastuse = jiffies; | |
107 | old_addr = p->old_addr; | |
108 | new_addr = p->new_addr; | |
109 | mask = p->mask; | |
110 | egress = p->flags & TCA_NAT_FLAG_EGRESS; | |
111 | action = p->tcf_action; | |
112 | ||
bfe0d029 | 113 | bstats_update(&p->tcf_bstats, skb); |
b4219952 HX |
114 | |
115 | spin_unlock(&p->tcf_lock); | |
116 | ||
117 | if (unlikely(action == TC_ACT_SHOT)) | |
118 | goto drop; | |
119 | ||
36d12690 CG |
120 | noff = skb_network_offset(skb); |
121 | if (!pskb_may_pull(skb, sizeof(*iph) + noff)) | |
b4219952 HX |
122 | goto drop; |
123 | ||
124 | iph = ip_hdr(skb); | |
125 | ||
126 | if (egress) | |
127 | addr = iph->saddr; | |
128 | else | |
129 | addr = iph->daddr; | |
130 | ||
131 | if (!((old_addr ^ addr) & mask)) { | |
3697649f | 132 | if (skb_try_make_writable(skb, sizeof(*iph) + noff)) |
b4219952 HX |
133 | goto drop; |
134 | ||
135 | new_addr &= mask; | |
136 | new_addr |= addr & ~mask; | |
137 | ||
138 | /* Rewrite IP header */ | |
139 | iph = ip_hdr(skb); | |
140 | if (egress) | |
141 | iph->saddr = new_addr; | |
142 | else | |
143 | iph->daddr = new_addr; | |
144 | ||
be0ea7d5 | 145 | csum_replace4(&iph->check, addr, new_addr); |
33c29dde CG |
146 | } else if ((iph->frag_off & htons(IP_OFFSET)) || |
147 | iph->protocol != IPPROTO_ICMP) { | |
148 | goto out; | |
b4219952 HX |
149 | } |
150 | ||
151 | ihl = iph->ihl * 4; | |
152 | ||
153 | /* It would be nice to share code with stateful NAT. */ | |
154 | switch (iph->frag_off & htons(IP_OFFSET) ? 0 : iph->protocol) { | |
155 | case IPPROTO_TCP: | |
156 | { | |
157 | struct tcphdr *tcph; | |
158 | ||
36d12690 | 159 | if (!pskb_may_pull(skb, ihl + sizeof(*tcph) + noff) || |
3697649f | 160 | skb_try_make_writable(skb, ihl + sizeof(*tcph) + noff)) |
b4219952 HX |
161 | goto drop; |
162 | ||
163 | tcph = (void *)(skb_network_header(skb) + ihl); | |
4b048d6d TH |
164 | inet_proto_csum_replace4(&tcph->check, skb, addr, new_addr, |
165 | true); | |
b4219952 HX |
166 | break; |
167 | } | |
168 | case IPPROTO_UDP: | |
169 | { | |
170 | struct udphdr *udph; | |
171 | ||
36d12690 | 172 | if (!pskb_may_pull(skb, ihl + sizeof(*udph) + noff) || |
3697649f | 173 | skb_try_make_writable(skb, ihl + sizeof(*udph) + noff)) |
b4219952 HX |
174 | goto drop; |
175 | ||
176 | udph = (void *)(skb_network_header(skb) + ihl); | |
177 | if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) { | |
be0ea7d5 | 178 | inet_proto_csum_replace4(&udph->check, skb, addr, |
4b048d6d | 179 | new_addr, true); |
b4219952 HX |
180 | if (!udph->check) |
181 | udph->check = CSUM_MANGLED_0; | |
182 | } | |
183 | break; | |
184 | } | |
185 | case IPPROTO_ICMP: | |
186 | { | |
187 | struct icmphdr *icmph; | |
188 | ||
36d12690 | 189 | if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + noff)) |
b4219952 HX |
190 | goto drop; |
191 | ||
192 | icmph = (void *)(skb_network_header(skb) + ihl); | |
193 | ||
194 | if ((icmph->type != ICMP_DEST_UNREACH) && | |
195 | (icmph->type != ICMP_TIME_EXCEEDED) && | |
196 | (icmph->type != ICMP_PARAMETERPROB)) | |
197 | break; | |
198 | ||
36d12690 CG |
199 | if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + sizeof(*iph) + |
200 | noff)) | |
70c2efa5 CG |
201 | goto drop; |
202 | ||
072d79a3 | 203 | icmph = (void *)(skb_network_header(skb) + ihl); |
b4219952 HX |
204 | iph = (void *)(icmph + 1); |
205 | if (egress) | |
206 | addr = iph->daddr; | |
207 | else | |
208 | addr = iph->saddr; | |
209 | ||
210 | if ((old_addr ^ addr) & mask) | |
211 | break; | |
212 | ||
3697649f DB |
213 | if (skb_try_make_writable(skb, ihl + sizeof(*icmph) + |
214 | sizeof(*iph) + noff)) | |
b4219952 HX |
215 | goto drop; |
216 | ||
217 | icmph = (void *)(skb_network_header(skb) + ihl); | |
218 | iph = (void *)(icmph + 1); | |
219 | ||
220 | new_addr &= mask; | |
221 | new_addr |= addr & ~mask; | |
222 | ||
223 | /* XXX Fix up the inner checksums. */ | |
224 | if (egress) | |
225 | iph->daddr = new_addr; | |
226 | else | |
227 | iph->saddr = new_addr; | |
228 | ||
be0ea7d5 | 229 | inet_proto_csum_replace4(&icmph->checksum, skb, addr, new_addr, |
4b048d6d | 230 | false); |
b4219952 HX |
231 | break; |
232 | } | |
233 | default: | |
234 | break; | |
235 | } | |
236 | ||
33c29dde | 237 | out: |
b4219952 HX |
238 | return action; |
239 | ||
240 | drop: | |
241 | spin_lock(&p->tcf_lock); | |
242 | p->tcf_qstats.drops++; | |
243 | spin_unlock(&p->tcf_lock); | |
244 | return TC_ACT_SHOT; | |
245 | } | |
246 | ||
247 | static int tcf_nat_dump(struct sk_buff *skb, struct tc_action *a, | |
248 | int bind, int ref) | |
249 | { | |
250 | unsigned char *b = skb_tail_pointer(skb); | |
251 | struct tcf_nat *p = a->priv; | |
1c40be12 ED |
252 | struct tc_nat opt = { |
253 | .old_addr = p->old_addr, | |
254 | .new_addr = p->new_addr, | |
255 | .mask = p->mask, | |
256 | .flags = p->flags, | |
257 | ||
258 | .index = p->tcf_index, | |
259 | .action = p->tcf_action, | |
260 | .refcnt = p->tcf_refcnt - ref, | |
261 | .bindcnt = p->tcf_bindcnt - bind, | |
262 | }; | |
b4219952 | 263 | struct tcf_t t; |
b4219952 | 264 | |
1b34ec43 DM |
265 | if (nla_put(skb, TCA_NAT_PARMS, sizeof(opt), &opt)) |
266 | goto nla_put_failure; | |
b4219952 HX |
267 | t.install = jiffies_to_clock_t(jiffies - p->tcf_tm.install); |
268 | t.lastuse = jiffies_to_clock_t(jiffies - p->tcf_tm.lastuse); | |
269 | t.expires = jiffies_to_clock_t(p->tcf_tm.expires); | |
1b34ec43 DM |
270 | if (nla_put(skb, TCA_NAT_TM, sizeof(t), &t)) |
271 | goto nla_put_failure; | |
b4219952 | 272 | |
b4219952 HX |
273 | return skb->len; |
274 | ||
7ba699c6 | 275 | nla_put_failure: |
b4219952 | 276 | nlmsg_trim(skb, b); |
b4219952 HX |
277 | return -1; |
278 | } | |
279 | ||
ddf97ccd WC |
280 | static int tcf_nat_walker(struct net *net, struct sk_buff *skb, |
281 | struct netlink_callback *cb, int type, | |
282 | struct tc_action *a) | |
283 | { | |
284 | struct tc_action_net *tn = net_generic(net, nat_net_id); | |
285 | ||
286 | return tcf_generic_walker(tn, skb, cb, type, a); | |
287 | } | |
288 | ||
289 | static int tcf_nat_search(struct net *net, struct tc_action *a, u32 index) | |
290 | { | |
291 | struct tc_action_net *tn = net_generic(net, nat_net_id); | |
292 | ||
293 | return tcf_hash_search(tn, a, index); | |
294 | } | |
295 | ||
b4219952 HX |
296 | static struct tc_action_ops act_nat_ops = { |
297 | .kind = "nat", | |
b4219952 | 298 | .type = TCA_ACT_NAT, |
b4219952 HX |
299 | .owner = THIS_MODULE, |
300 | .act = tcf_nat, | |
301 | .dump = tcf_nat_dump, | |
b4219952 | 302 | .init = tcf_nat_init, |
ddf97ccd WC |
303 | .walk = tcf_nat_walker, |
304 | .lookup = tcf_nat_search, | |
305 | }; | |
306 | ||
307 | static __net_init int nat_init_net(struct net *net) | |
308 | { | |
309 | struct tc_action_net *tn = net_generic(net, nat_net_id); | |
310 | ||
311 | return tc_action_net_init(tn, &act_nat_ops, NAT_TAB_MASK); | |
312 | } | |
313 | ||
314 | static void __net_exit nat_exit_net(struct net *net) | |
315 | { | |
316 | struct tc_action_net *tn = net_generic(net, nat_net_id); | |
317 | ||
318 | tc_action_net_exit(tn); | |
319 | } | |
320 | ||
321 | static struct pernet_operations nat_net_ops = { | |
322 | .init = nat_init_net, | |
323 | .exit = nat_exit_net, | |
324 | .id = &nat_net_id, | |
325 | .size = sizeof(struct tc_action_net), | |
b4219952 HX |
326 | }; |
327 | ||
328 | MODULE_DESCRIPTION("Stateless NAT actions"); | |
329 | MODULE_LICENSE("GPL"); | |
330 | ||
331 | static int __init nat_init_module(void) | |
332 | { | |
ddf97ccd | 333 | return tcf_register_action(&act_nat_ops, &nat_net_ops); |
b4219952 HX |
334 | } |
335 | ||
336 | static void __exit nat_cleanup_module(void) | |
337 | { | |
ddf97ccd | 338 | tcf_unregister_action(&act_nat_ops, &nat_net_ops); |
b4219952 HX |
339 | } |
340 | ||
341 | module_init(nat_init_module); | |
342 | module_exit(nat_cleanup_module); |