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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 | |
33 | static struct tcf_common *tcf_nat_ht[NAT_TAB_MASK + 1]; | |
34 | static u32 nat_idx_gen; | |
35 | static DEFINE_RWLOCK(nat_lock); | |
36 | ||
37 | static struct tcf_hashinfo nat_hash_info = { | |
38 | .htab = tcf_nat_ht, | |
39 | .hmask = NAT_TAB_MASK, | |
40 | .lock = &nat_lock, | |
41 | }; | |
42 | ||
53b2bf3f PM |
43 | static const struct nla_policy nat_policy[TCA_NAT_MAX + 1] = { |
44 | [TCA_NAT_PARMS] = { .len = sizeof(struct tc_nat) }, | |
45 | }; | |
46 | ||
7ba699c6 | 47 | static int tcf_nat_init(struct nlattr *nla, struct nlattr *est, |
b4219952 HX |
48 | struct tc_action *a, int ovr, int bind) |
49 | { | |
7ba699c6 | 50 | struct nlattr *tb[TCA_NAT_MAX + 1]; |
b4219952 | 51 | struct tc_nat *parm; |
cee63723 | 52 | int ret = 0, err; |
b4219952 HX |
53 | struct tcf_nat *p; |
54 | struct tcf_common *pc; | |
55 | ||
cee63723 | 56 | if (nla == NULL) |
b4219952 HX |
57 | return -EINVAL; |
58 | ||
53b2bf3f | 59 | err = nla_parse_nested(tb, TCA_NAT_MAX, nla, nat_policy); |
cee63723 PM |
60 | if (err < 0) |
61 | return err; | |
62 | ||
53b2bf3f | 63 | if (tb[TCA_NAT_PARMS] == NULL) |
b4219952 | 64 | return -EINVAL; |
7ba699c6 | 65 | parm = nla_data(tb[TCA_NAT_PARMS]); |
b4219952 HX |
66 | |
67 | pc = tcf_hash_check(parm->index, a, bind, &nat_hash_info); | |
68 | if (!pc) { | |
69 | pc = tcf_hash_create(parm->index, est, a, sizeof(*p), bind, | |
70 | &nat_idx_gen, &nat_hash_info); | |
0e991ec6 | 71 | if (IS_ERR(pc)) |
cc7ec456 | 72 | return PTR_ERR(pc); |
b4219952 HX |
73 | p = to_tcf_nat(pc); |
74 | ret = ACT_P_CREATED; | |
75 | } else { | |
76 | p = to_tcf_nat(pc); | |
77 | if (!ovr) { | |
78 | tcf_hash_release(pc, bind, &nat_hash_info); | |
79 | return -EEXIST; | |
80 | } | |
81 | } | |
82 | ||
83 | spin_lock_bh(&p->tcf_lock); | |
84 | p->old_addr = parm->old_addr; | |
85 | p->new_addr = parm->new_addr; | |
86 | p->mask = parm->mask; | |
87 | p->flags = parm->flags; | |
88 | ||
89 | p->tcf_action = parm->action; | |
90 | spin_unlock_bh(&p->tcf_lock); | |
91 | ||
92 | if (ret == ACT_P_CREATED) | |
93 | tcf_hash_insert(pc, &nat_hash_info); | |
94 | ||
95 | return ret; | |
96 | } | |
97 | ||
98 | static int tcf_nat_cleanup(struct tc_action *a, int bind) | |
99 | { | |
100 | struct tcf_nat *p = a->priv; | |
101 | ||
102 | return tcf_hash_release(&p->common, bind, &nat_hash_info); | |
103 | } | |
104 | ||
dc7f9f6e | 105 | static int tcf_nat(struct sk_buff *skb, const struct tc_action *a, |
b4219952 HX |
106 | struct tcf_result *res) |
107 | { | |
108 | struct tcf_nat *p = a->priv; | |
109 | struct iphdr *iph; | |
110 | __be32 old_addr; | |
111 | __be32 new_addr; | |
112 | __be32 mask; | |
113 | __be32 addr; | |
114 | int egress; | |
115 | int action; | |
116 | int ihl; | |
36d12690 | 117 | int noff; |
b4219952 HX |
118 | |
119 | spin_lock(&p->tcf_lock); | |
120 | ||
121 | p->tcf_tm.lastuse = jiffies; | |
122 | old_addr = p->old_addr; | |
123 | new_addr = p->new_addr; | |
124 | mask = p->mask; | |
125 | egress = p->flags & TCA_NAT_FLAG_EGRESS; | |
126 | action = p->tcf_action; | |
127 | ||
bfe0d029 | 128 | bstats_update(&p->tcf_bstats, skb); |
b4219952 HX |
129 | |
130 | spin_unlock(&p->tcf_lock); | |
131 | ||
132 | if (unlikely(action == TC_ACT_SHOT)) | |
133 | goto drop; | |
134 | ||
36d12690 CG |
135 | noff = skb_network_offset(skb); |
136 | if (!pskb_may_pull(skb, sizeof(*iph) + noff)) | |
b4219952 HX |
137 | goto drop; |
138 | ||
139 | iph = ip_hdr(skb); | |
140 | ||
141 | if (egress) | |
142 | addr = iph->saddr; | |
143 | else | |
144 | addr = iph->daddr; | |
145 | ||
146 | if (!((old_addr ^ addr) & mask)) { | |
147 | if (skb_cloned(skb) && | |
36d12690 | 148 | !skb_clone_writable(skb, sizeof(*iph) + noff) && |
b4219952 HX |
149 | pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) |
150 | goto drop; | |
151 | ||
152 | new_addr &= mask; | |
153 | new_addr |= addr & ~mask; | |
154 | ||
155 | /* Rewrite IP header */ | |
156 | iph = ip_hdr(skb); | |
157 | if (egress) | |
158 | iph->saddr = new_addr; | |
159 | else | |
160 | iph->daddr = new_addr; | |
161 | ||
be0ea7d5 | 162 | csum_replace4(&iph->check, addr, new_addr); |
33c29dde CG |
163 | } else if ((iph->frag_off & htons(IP_OFFSET)) || |
164 | iph->protocol != IPPROTO_ICMP) { | |
165 | goto out; | |
b4219952 HX |
166 | } |
167 | ||
168 | ihl = iph->ihl * 4; | |
169 | ||
170 | /* It would be nice to share code with stateful NAT. */ | |
171 | switch (iph->frag_off & htons(IP_OFFSET) ? 0 : iph->protocol) { | |
172 | case IPPROTO_TCP: | |
173 | { | |
174 | struct tcphdr *tcph; | |
175 | ||
36d12690 | 176 | if (!pskb_may_pull(skb, ihl + sizeof(*tcph) + noff) || |
b4219952 | 177 | (skb_cloned(skb) && |
36d12690 | 178 | !skb_clone_writable(skb, ihl + sizeof(*tcph) + noff) && |
b4219952 HX |
179 | pskb_expand_head(skb, 0, 0, GFP_ATOMIC))) |
180 | goto drop; | |
181 | ||
182 | tcph = (void *)(skb_network_header(skb) + ihl); | |
be0ea7d5 | 183 | inet_proto_csum_replace4(&tcph->check, skb, addr, new_addr, 1); |
b4219952 HX |
184 | break; |
185 | } | |
186 | case IPPROTO_UDP: | |
187 | { | |
188 | struct udphdr *udph; | |
189 | ||
36d12690 | 190 | if (!pskb_may_pull(skb, ihl + sizeof(*udph) + noff) || |
b4219952 | 191 | (skb_cloned(skb) && |
36d12690 | 192 | !skb_clone_writable(skb, ihl + sizeof(*udph) + noff) && |
b4219952 HX |
193 | pskb_expand_head(skb, 0, 0, GFP_ATOMIC))) |
194 | goto drop; | |
195 | ||
196 | udph = (void *)(skb_network_header(skb) + ihl); | |
197 | if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) { | |
be0ea7d5 PM |
198 | inet_proto_csum_replace4(&udph->check, skb, addr, |
199 | new_addr, 1); | |
b4219952 HX |
200 | if (!udph->check) |
201 | udph->check = CSUM_MANGLED_0; | |
202 | } | |
203 | break; | |
204 | } | |
205 | case IPPROTO_ICMP: | |
206 | { | |
207 | struct icmphdr *icmph; | |
208 | ||
36d12690 | 209 | if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + noff)) |
b4219952 HX |
210 | goto drop; |
211 | ||
212 | icmph = (void *)(skb_network_header(skb) + ihl); | |
213 | ||
214 | if ((icmph->type != ICMP_DEST_UNREACH) && | |
215 | (icmph->type != ICMP_TIME_EXCEEDED) && | |
216 | (icmph->type != ICMP_PARAMETERPROB)) | |
217 | break; | |
218 | ||
36d12690 CG |
219 | if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + sizeof(*iph) + |
220 | noff)) | |
70c2efa5 CG |
221 | goto drop; |
222 | ||
072d79a3 | 223 | icmph = (void *)(skb_network_header(skb) + ihl); |
b4219952 HX |
224 | iph = (void *)(icmph + 1); |
225 | if (egress) | |
226 | addr = iph->daddr; | |
227 | else | |
228 | addr = iph->saddr; | |
229 | ||
230 | if ((old_addr ^ addr) & mask) | |
231 | break; | |
232 | ||
233 | if (skb_cloned(skb) && | |
36d12690 CG |
234 | !skb_clone_writable(skb, ihl + sizeof(*icmph) + |
235 | sizeof(*iph) + noff) && | |
b4219952 HX |
236 | pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) |
237 | goto drop; | |
238 | ||
239 | icmph = (void *)(skb_network_header(skb) + ihl); | |
240 | iph = (void *)(icmph + 1); | |
241 | ||
242 | new_addr &= mask; | |
243 | new_addr |= addr & ~mask; | |
244 | ||
245 | /* XXX Fix up the inner checksums. */ | |
246 | if (egress) | |
247 | iph->daddr = new_addr; | |
248 | else | |
249 | iph->saddr = new_addr; | |
250 | ||
be0ea7d5 | 251 | inet_proto_csum_replace4(&icmph->checksum, skb, addr, new_addr, |
3a3dfb06 | 252 | 0); |
b4219952 HX |
253 | break; |
254 | } | |
255 | default: | |
256 | break; | |
257 | } | |
258 | ||
33c29dde | 259 | out: |
b4219952 HX |
260 | return action; |
261 | ||
262 | drop: | |
263 | spin_lock(&p->tcf_lock); | |
264 | p->tcf_qstats.drops++; | |
265 | spin_unlock(&p->tcf_lock); | |
266 | return TC_ACT_SHOT; | |
267 | } | |
268 | ||
269 | static int tcf_nat_dump(struct sk_buff *skb, struct tc_action *a, | |
270 | int bind, int ref) | |
271 | { | |
272 | unsigned char *b = skb_tail_pointer(skb); | |
273 | struct tcf_nat *p = a->priv; | |
1c40be12 ED |
274 | struct tc_nat opt = { |
275 | .old_addr = p->old_addr, | |
276 | .new_addr = p->new_addr, | |
277 | .mask = p->mask, | |
278 | .flags = p->flags, | |
279 | ||
280 | .index = p->tcf_index, | |
281 | .action = p->tcf_action, | |
282 | .refcnt = p->tcf_refcnt - ref, | |
283 | .bindcnt = p->tcf_bindcnt - bind, | |
284 | }; | |
b4219952 | 285 | struct tcf_t t; |
b4219952 | 286 | |
1b34ec43 DM |
287 | if (nla_put(skb, TCA_NAT_PARMS, sizeof(opt), &opt)) |
288 | goto nla_put_failure; | |
b4219952 HX |
289 | t.install = jiffies_to_clock_t(jiffies - p->tcf_tm.install); |
290 | t.lastuse = jiffies_to_clock_t(jiffies - p->tcf_tm.lastuse); | |
291 | t.expires = jiffies_to_clock_t(p->tcf_tm.expires); | |
1b34ec43 DM |
292 | if (nla_put(skb, TCA_NAT_TM, sizeof(t), &t)) |
293 | goto nla_put_failure; | |
b4219952 | 294 | |
b4219952 HX |
295 | return skb->len; |
296 | ||
7ba699c6 | 297 | nla_put_failure: |
b4219952 | 298 | nlmsg_trim(skb, b); |
b4219952 HX |
299 | return -1; |
300 | } | |
301 | ||
302 | static struct tc_action_ops act_nat_ops = { | |
303 | .kind = "nat", | |
304 | .hinfo = &nat_hash_info, | |
305 | .type = TCA_ACT_NAT, | |
306 | .capab = TCA_CAP_NONE, | |
307 | .owner = THIS_MODULE, | |
308 | .act = tcf_nat, | |
309 | .dump = tcf_nat_dump, | |
310 | .cleanup = tcf_nat_cleanup, | |
311 | .lookup = tcf_hash_search, | |
312 | .init = tcf_nat_init, | |
313 | .walk = tcf_generic_walker | |
314 | }; | |
315 | ||
316 | MODULE_DESCRIPTION("Stateless NAT actions"); | |
317 | MODULE_LICENSE("GPL"); | |
318 | ||
319 | static int __init nat_init_module(void) | |
320 | { | |
321 | return tcf_register_action(&act_nat_ops); | |
322 | } | |
323 | ||
324 | static void __exit nat_cleanup_module(void) | |
325 | { | |
326 | tcf_unregister_action(&act_nat_ops); | |
327 | } | |
328 | ||
329 | module_init(nat_init_module); | |
330 | module_exit(nat_cleanup_module); |