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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 | |
53b2bf3f PM |
34 | static const struct nla_policy nat_policy[TCA_NAT_MAX + 1] = { |
35 | [TCA_NAT_PARMS] = { .len = sizeof(struct tc_nat) }, | |
36 | }; | |
37 | ||
c1b52739 | 38 | static int tcf_nat_init(struct net *net, struct nlattr *nla, struct nlattr *est, |
b4219952 HX |
39 | struct tc_action *a, int ovr, int bind) |
40 | { | |
7ba699c6 | 41 | struct nlattr *tb[TCA_NAT_MAX + 1]; |
b4219952 | 42 | struct tc_nat *parm; |
cee63723 | 43 | int ret = 0, err; |
b4219952 | 44 | struct tcf_nat *p; |
b4219952 | 45 | |
cee63723 | 46 | if (nla == NULL) |
b4219952 HX |
47 | return -EINVAL; |
48 | ||
53b2bf3f | 49 | err = nla_parse_nested(tb, TCA_NAT_MAX, nla, nat_policy); |
cee63723 PM |
50 | if (err < 0) |
51 | return err; | |
52 | ||
53b2bf3f | 53 | if (tb[TCA_NAT_PARMS] == NULL) |
b4219952 | 54 | return -EINVAL; |
7ba699c6 | 55 | parm = nla_data(tb[TCA_NAT_PARMS]); |
b4219952 | 56 | |
86062033 | 57 | if (!tcf_hash_check(parm->index, a, bind)) { |
519c818e ED |
58 | ret = tcf_hash_create(parm->index, est, a, sizeof(*p), |
59 | bind, false); | |
86062033 WC |
60 | if (ret) |
61 | return ret; | |
b4219952 HX |
62 | ret = ACT_P_CREATED; |
63 | } else { | |
1a29321e JHS |
64 | if (bind) |
65 | return 0; | |
86062033 | 66 | tcf_hash_release(a, bind); |
1a29321e | 67 | if (!ovr) |
b4219952 | 68 | return -EEXIST; |
b4219952 | 69 | } |
86062033 | 70 | p = to_tcf_nat(a); |
b4219952 HX |
71 | |
72 | spin_lock_bh(&p->tcf_lock); | |
73 | p->old_addr = parm->old_addr; | |
74 | p->new_addr = parm->new_addr; | |
75 | p->mask = parm->mask; | |
76 | p->flags = parm->flags; | |
77 | ||
78 | p->tcf_action = parm->action; | |
79 | spin_unlock_bh(&p->tcf_lock); | |
80 | ||
81 | if (ret == ACT_P_CREATED) | |
86062033 | 82 | tcf_hash_insert(a); |
b4219952 HX |
83 | |
84 | return ret; | |
85 | } | |
86 | ||
dc7f9f6e | 87 | static int tcf_nat(struct sk_buff *skb, const struct tc_action *a, |
b4219952 HX |
88 | struct tcf_result *res) |
89 | { | |
90 | struct tcf_nat *p = a->priv; | |
91 | struct iphdr *iph; | |
92 | __be32 old_addr; | |
93 | __be32 new_addr; | |
94 | __be32 mask; | |
95 | __be32 addr; | |
96 | int egress; | |
97 | int action; | |
98 | int ihl; | |
36d12690 | 99 | int noff; |
b4219952 HX |
100 | |
101 | spin_lock(&p->tcf_lock); | |
102 | ||
103 | p->tcf_tm.lastuse = jiffies; | |
104 | old_addr = p->old_addr; | |
105 | new_addr = p->new_addr; | |
106 | mask = p->mask; | |
107 | egress = p->flags & TCA_NAT_FLAG_EGRESS; | |
108 | action = p->tcf_action; | |
109 | ||
bfe0d029 | 110 | bstats_update(&p->tcf_bstats, skb); |
b4219952 HX |
111 | |
112 | spin_unlock(&p->tcf_lock); | |
113 | ||
114 | if (unlikely(action == TC_ACT_SHOT)) | |
115 | goto drop; | |
116 | ||
36d12690 CG |
117 | noff = skb_network_offset(skb); |
118 | if (!pskb_may_pull(skb, sizeof(*iph) + noff)) | |
b4219952 HX |
119 | goto drop; |
120 | ||
121 | iph = ip_hdr(skb); | |
122 | ||
123 | if (egress) | |
124 | addr = iph->saddr; | |
125 | else | |
126 | addr = iph->daddr; | |
127 | ||
128 | if (!((old_addr ^ addr) & mask)) { | |
3697649f | 129 | if (skb_try_make_writable(skb, sizeof(*iph) + noff)) |
b4219952 HX |
130 | goto drop; |
131 | ||
132 | new_addr &= mask; | |
133 | new_addr |= addr & ~mask; | |
134 | ||
135 | /* Rewrite IP header */ | |
136 | iph = ip_hdr(skb); | |
137 | if (egress) | |
138 | iph->saddr = new_addr; | |
139 | else | |
140 | iph->daddr = new_addr; | |
141 | ||
be0ea7d5 | 142 | csum_replace4(&iph->check, addr, new_addr); |
33c29dde CG |
143 | } else if ((iph->frag_off & htons(IP_OFFSET)) || |
144 | iph->protocol != IPPROTO_ICMP) { | |
145 | goto out; | |
b4219952 HX |
146 | } |
147 | ||
148 | ihl = iph->ihl * 4; | |
149 | ||
150 | /* It would be nice to share code with stateful NAT. */ | |
151 | switch (iph->frag_off & htons(IP_OFFSET) ? 0 : iph->protocol) { | |
152 | case IPPROTO_TCP: | |
153 | { | |
154 | struct tcphdr *tcph; | |
155 | ||
36d12690 | 156 | if (!pskb_may_pull(skb, ihl + sizeof(*tcph) + noff) || |
3697649f | 157 | skb_try_make_writable(skb, ihl + sizeof(*tcph) + noff)) |
b4219952 HX |
158 | goto drop; |
159 | ||
160 | tcph = (void *)(skb_network_header(skb) + ihl); | |
4b048d6d TH |
161 | inet_proto_csum_replace4(&tcph->check, skb, addr, new_addr, |
162 | true); | |
b4219952 HX |
163 | break; |
164 | } | |
165 | case IPPROTO_UDP: | |
166 | { | |
167 | struct udphdr *udph; | |
168 | ||
36d12690 | 169 | if (!pskb_may_pull(skb, ihl + sizeof(*udph) + noff) || |
3697649f | 170 | skb_try_make_writable(skb, ihl + sizeof(*udph) + noff)) |
b4219952 HX |
171 | goto drop; |
172 | ||
173 | udph = (void *)(skb_network_header(skb) + ihl); | |
174 | if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) { | |
be0ea7d5 | 175 | inet_proto_csum_replace4(&udph->check, skb, addr, |
4b048d6d | 176 | new_addr, true); |
b4219952 HX |
177 | if (!udph->check) |
178 | udph->check = CSUM_MANGLED_0; | |
179 | } | |
180 | break; | |
181 | } | |
182 | case IPPROTO_ICMP: | |
183 | { | |
184 | struct icmphdr *icmph; | |
185 | ||
36d12690 | 186 | if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + noff)) |
b4219952 HX |
187 | goto drop; |
188 | ||
189 | icmph = (void *)(skb_network_header(skb) + ihl); | |
190 | ||
191 | if ((icmph->type != ICMP_DEST_UNREACH) && | |
192 | (icmph->type != ICMP_TIME_EXCEEDED) && | |
193 | (icmph->type != ICMP_PARAMETERPROB)) | |
194 | break; | |
195 | ||
36d12690 CG |
196 | if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + sizeof(*iph) + |
197 | noff)) | |
70c2efa5 CG |
198 | goto drop; |
199 | ||
072d79a3 | 200 | icmph = (void *)(skb_network_header(skb) + ihl); |
b4219952 HX |
201 | iph = (void *)(icmph + 1); |
202 | if (egress) | |
203 | addr = iph->daddr; | |
204 | else | |
205 | addr = iph->saddr; | |
206 | ||
207 | if ((old_addr ^ addr) & mask) | |
208 | break; | |
209 | ||
3697649f DB |
210 | if (skb_try_make_writable(skb, ihl + sizeof(*icmph) + |
211 | sizeof(*iph) + noff)) | |
b4219952 HX |
212 | goto drop; |
213 | ||
214 | icmph = (void *)(skb_network_header(skb) + ihl); | |
215 | iph = (void *)(icmph + 1); | |
216 | ||
217 | new_addr &= mask; | |
218 | new_addr |= addr & ~mask; | |
219 | ||
220 | /* XXX Fix up the inner checksums. */ | |
221 | if (egress) | |
222 | iph->daddr = new_addr; | |
223 | else | |
224 | iph->saddr = new_addr; | |
225 | ||
be0ea7d5 | 226 | inet_proto_csum_replace4(&icmph->checksum, skb, addr, new_addr, |
4b048d6d | 227 | false); |
b4219952 HX |
228 | break; |
229 | } | |
230 | default: | |
231 | break; | |
232 | } | |
233 | ||
33c29dde | 234 | out: |
b4219952 HX |
235 | return action; |
236 | ||
237 | drop: | |
238 | spin_lock(&p->tcf_lock); | |
239 | p->tcf_qstats.drops++; | |
240 | spin_unlock(&p->tcf_lock); | |
241 | return TC_ACT_SHOT; | |
242 | } | |
243 | ||
244 | static int tcf_nat_dump(struct sk_buff *skb, struct tc_action *a, | |
245 | int bind, int ref) | |
246 | { | |
247 | unsigned char *b = skb_tail_pointer(skb); | |
248 | struct tcf_nat *p = a->priv; | |
1c40be12 ED |
249 | struct tc_nat opt = { |
250 | .old_addr = p->old_addr, | |
251 | .new_addr = p->new_addr, | |
252 | .mask = p->mask, | |
253 | .flags = p->flags, | |
254 | ||
255 | .index = p->tcf_index, | |
256 | .action = p->tcf_action, | |
257 | .refcnt = p->tcf_refcnt - ref, | |
258 | .bindcnt = p->tcf_bindcnt - bind, | |
259 | }; | |
b4219952 | 260 | struct tcf_t t; |
b4219952 | 261 | |
1b34ec43 DM |
262 | if (nla_put(skb, TCA_NAT_PARMS, sizeof(opt), &opt)) |
263 | goto nla_put_failure; | |
b4219952 HX |
264 | t.install = jiffies_to_clock_t(jiffies - p->tcf_tm.install); |
265 | t.lastuse = jiffies_to_clock_t(jiffies - p->tcf_tm.lastuse); | |
266 | t.expires = jiffies_to_clock_t(p->tcf_tm.expires); | |
1b34ec43 DM |
267 | if (nla_put(skb, TCA_NAT_TM, sizeof(t), &t)) |
268 | goto nla_put_failure; | |
b4219952 | 269 | |
b4219952 HX |
270 | return skb->len; |
271 | ||
7ba699c6 | 272 | nla_put_failure: |
b4219952 | 273 | nlmsg_trim(skb, b); |
b4219952 HX |
274 | return -1; |
275 | } | |
276 | ||
277 | static struct tc_action_ops act_nat_ops = { | |
278 | .kind = "nat", | |
b4219952 | 279 | .type = TCA_ACT_NAT, |
b4219952 HX |
280 | .owner = THIS_MODULE, |
281 | .act = tcf_nat, | |
282 | .dump = tcf_nat_dump, | |
b4219952 | 283 | .init = tcf_nat_init, |
b4219952 HX |
284 | }; |
285 | ||
286 | MODULE_DESCRIPTION("Stateless NAT actions"); | |
287 | MODULE_LICENSE("GPL"); | |
288 | ||
289 | static int __init nat_init_module(void) | |
290 | { | |
4f1e9d89 | 291 | return tcf_register_action(&act_nat_ops, NAT_TAB_MASK); |
b4219952 HX |
292 | } |
293 | ||
294 | static void __exit nat_cleanup_module(void) | |
295 | { | |
296 | tcf_unregister_action(&act_nat_ops); | |
297 | } | |
298 | ||
299 | module_init(nat_init_module); | |
300 | module_exit(nat_cleanup_module); |