Commit | Line | Data |
---|---|---|
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 WC |
57 | if (!tcf_hash_check(parm->index, a, bind)) { |
58 | ret = tcf_hash_create(parm->index, est, a, sizeof(*p), bind); | |
59 | if (ret) | |
60 | return ret; | |
b4219952 HX |
61 | ret = ACT_P_CREATED; |
62 | } else { | |
1a29321e JHS |
63 | if (bind) |
64 | return 0; | |
86062033 | 65 | tcf_hash_release(a, bind); |
1a29321e | 66 | if (!ovr) |
b4219952 | 67 | return -EEXIST; |
b4219952 | 68 | } |
86062033 | 69 | p = to_tcf_nat(a); |
b4219952 HX |
70 | |
71 | spin_lock_bh(&p->tcf_lock); | |
72 | p->old_addr = parm->old_addr; | |
73 | p->new_addr = parm->new_addr; | |
74 | p->mask = parm->mask; | |
75 | p->flags = parm->flags; | |
76 | ||
77 | p->tcf_action = parm->action; | |
78 | spin_unlock_bh(&p->tcf_lock); | |
79 | ||
80 | if (ret == ACT_P_CREATED) | |
86062033 | 81 | tcf_hash_insert(a); |
b4219952 HX |
82 | |
83 | return ret; | |
84 | } | |
85 | ||
dc7f9f6e | 86 | static int tcf_nat(struct sk_buff *skb, const struct tc_action *a, |
b4219952 HX |
87 | struct tcf_result *res) |
88 | { | |
89 | struct tcf_nat *p = a->priv; | |
90 | struct iphdr *iph; | |
91 | __be32 old_addr; | |
92 | __be32 new_addr; | |
93 | __be32 mask; | |
94 | __be32 addr; | |
95 | int egress; | |
96 | int action; | |
97 | int ihl; | |
36d12690 | 98 | int noff; |
b4219952 HX |
99 | |
100 | spin_lock(&p->tcf_lock); | |
101 | ||
102 | p->tcf_tm.lastuse = jiffies; | |
103 | old_addr = p->old_addr; | |
104 | new_addr = p->new_addr; | |
105 | mask = p->mask; | |
106 | egress = p->flags & TCA_NAT_FLAG_EGRESS; | |
107 | action = p->tcf_action; | |
108 | ||
bfe0d029 | 109 | bstats_update(&p->tcf_bstats, skb); |
b4219952 HX |
110 | |
111 | spin_unlock(&p->tcf_lock); | |
112 | ||
113 | if (unlikely(action == TC_ACT_SHOT)) | |
114 | goto drop; | |
115 | ||
36d12690 CG |
116 | noff = skb_network_offset(skb); |
117 | if (!pskb_may_pull(skb, sizeof(*iph) + noff)) | |
b4219952 HX |
118 | goto drop; |
119 | ||
120 | iph = ip_hdr(skb); | |
121 | ||
122 | if (egress) | |
123 | addr = iph->saddr; | |
124 | else | |
125 | addr = iph->daddr; | |
126 | ||
127 | if (!((old_addr ^ addr) & mask)) { | |
128 | if (skb_cloned(skb) && | |
36d12690 | 129 | !skb_clone_writable(skb, sizeof(*iph) + noff) && |
b4219952 HX |
130 | pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) |
131 | goto drop; | |
132 | ||
133 | new_addr &= mask; | |
134 | new_addr |= addr & ~mask; | |
135 | ||
136 | /* Rewrite IP header */ | |
137 | iph = ip_hdr(skb); | |
138 | if (egress) | |
139 | iph->saddr = new_addr; | |
140 | else | |
141 | iph->daddr = new_addr; | |
142 | ||
be0ea7d5 | 143 | csum_replace4(&iph->check, addr, new_addr); |
33c29dde CG |
144 | } else if ((iph->frag_off & htons(IP_OFFSET)) || |
145 | iph->protocol != IPPROTO_ICMP) { | |
146 | goto out; | |
b4219952 HX |
147 | } |
148 | ||
149 | ihl = iph->ihl * 4; | |
150 | ||
151 | /* It would be nice to share code with stateful NAT. */ | |
152 | switch (iph->frag_off & htons(IP_OFFSET) ? 0 : iph->protocol) { | |
153 | case IPPROTO_TCP: | |
154 | { | |
155 | struct tcphdr *tcph; | |
156 | ||
36d12690 | 157 | if (!pskb_may_pull(skb, ihl + sizeof(*tcph) + noff) || |
b4219952 | 158 | (skb_cloned(skb) && |
36d12690 | 159 | !skb_clone_writable(skb, ihl + sizeof(*tcph) + noff) && |
b4219952 HX |
160 | pskb_expand_head(skb, 0, 0, GFP_ATOMIC))) |
161 | goto drop; | |
162 | ||
163 | tcph = (void *)(skb_network_header(skb) + ihl); | |
be0ea7d5 | 164 | inet_proto_csum_replace4(&tcph->check, skb, addr, new_addr, 1); |
b4219952 HX |
165 | break; |
166 | } | |
167 | case IPPROTO_UDP: | |
168 | { | |
169 | struct udphdr *udph; | |
170 | ||
36d12690 | 171 | if (!pskb_may_pull(skb, ihl + sizeof(*udph) + noff) || |
b4219952 | 172 | (skb_cloned(skb) && |
36d12690 | 173 | !skb_clone_writable(skb, ihl + sizeof(*udph) + noff) && |
b4219952 HX |
174 | pskb_expand_head(skb, 0, 0, GFP_ATOMIC))) |
175 | goto drop; | |
176 | ||
177 | udph = (void *)(skb_network_header(skb) + ihl); | |
178 | if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) { | |
be0ea7d5 PM |
179 | inet_proto_csum_replace4(&udph->check, skb, addr, |
180 | new_addr, 1); | |
b4219952 HX |
181 | if (!udph->check) |
182 | udph->check = CSUM_MANGLED_0; | |
183 | } | |
184 | break; | |
185 | } | |
186 | case IPPROTO_ICMP: | |
187 | { | |
188 | struct icmphdr *icmph; | |
189 | ||
36d12690 | 190 | if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + noff)) |
b4219952 HX |
191 | goto drop; |
192 | ||
193 | icmph = (void *)(skb_network_header(skb) + ihl); | |
194 | ||
195 | if ((icmph->type != ICMP_DEST_UNREACH) && | |
196 | (icmph->type != ICMP_TIME_EXCEEDED) && | |
197 | (icmph->type != ICMP_PARAMETERPROB)) | |
198 | break; | |
199 | ||
36d12690 CG |
200 | if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + sizeof(*iph) + |
201 | noff)) | |
70c2efa5 CG |
202 | goto drop; |
203 | ||
072d79a3 | 204 | icmph = (void *)(skb_network_header(skb) + ihl); |
b4219952 HX |
205 | iph = (void *)(icmph + 1); |
206 | if (egress) | |
207 | addr = iph->daddr; | |
208 | else | |
209 | addr = iph->saddr; | |
210 | ||
211 | if ((old_addr ^ addr) & mask) | |
212 | break; | |
213 | ||
214 | if (skb_cloned(skb) && | |
36d12690 CG |
215 | !skb_clone_writable(skb, ihl + sizeof(*icmph) + |
216 | sizeof(*iph) + noff) && | |
b4219952 HX |
217 | pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) |
218 | goto drop; | |
219 | ||
220 | icmph = (void *)(skb_network_header(skb) + ihl); | |
221 | iph = (void *)(icmph + 1); | |
222 | ||
223 | new_addr &= mask; | |
224 | new_addr |= addr & ~mask; | |
225 | ||
226 | /* XXX Fix up the inner checksums. */ | |
227 | if (egress) | |
228 | iph->daddr = new_addr; | |
229 | else | |
230 | iph->saddr = new_addr; | |
231 | ||
be0ea7d5 | 232 | inet_proto_csum_replace4(&icmph->checksum, skb, addr, new_addr, |
3a3dfb06 | 233 | 0); |
b4219952 HX |
234 | break; |
235 | } | |
236 | default: | |
237 | break; | |
238 | } | |
239 | ||
33c29dde | 240 | out: |
b4219952 HX |
241 | return action; |
242 | ||
243 | drop: | |
244 | spin_lock(&p->tcf_lock); | |
245 | p->tcf_qstats.drops++; | |
246 | spin_unlock(&p->tcf_lock); | |
247 | return TC_ACT_SHOT; | |
248 | } | |
249 | ||
250 | static int tcf_nat_dump(struct sk_buff *skb, struct tc_action *a, | |
251 | int bind, int ref) | |
252 | { | |
253 | unsigned char *b = skb_tail_pointer(skb); | |
254 | struct tcf_nat *p = a->priv; | |
1c40be12 ED |
255 | struct tc_nat opt = { |
256 | .old_addr = p->old_addr, | |
257 | .new_addr = p->new_addr, | |
258 | .mask = p->mask, | |
259 | .flags = p->flags, | |
260 | ||
261 | .index = p->tcf_index, | |
262 | .action = p->tcf_action, | |
263 | .refcnt = p->tcf_refcnt - ref, | |
264 | .bindcnt = p->tcf_bindcnt - bind, | |
265 | }; | |
b4219952 | 266 | struct tcf_t t; |
b4219952 | 267 | |
1b34ec43 DM |
268 | if (nla_put(skb, TCA_NAT_PARMS, sizeof(opt), &opt)) |
269 | goto nla_put_failure; | |
b4219952 HX |
270 | t.install = jiffies_to_clock_t(jiffies - p->tcf_tm.install); |
271 | t.lastuse = jiffies_to_clock_t(jiffies - p->tcf_tm.lastuse); | |
272 | t.expires = jiffies_to_clock_t(p->tcf_tm.expires); | |
1b34ec43 DM |
273 | if (nla_put(skb, TCA_NAT_TM, sizeof(t), &t)) |
274 | goto nla_put_failure; | |
b4219952 | 275 | |
b4219952 HX |
276 | return skb->len; |
277 | ||
7ba699c6 | 278 | nla_put_failure: |
b4219952 | 279 | nlmsg_trim(skb, b); |
b4219952 HX |
280 | return -1; |
281 | } | |
282 | ||
283 | static struct tc_action_ops act_nat_ops = { | |
284 | .kind = "nat", | |
b4219952 | 285 | .type = TCA_ACT_NAT, |
b4219952 HX |
286 | .owner = THIS_MODULE, |
287 | .act = tcf_nat, | |
288 | .dump = tcf_nat_dump, | |
b4219952 | 289 | .init = tcf_nat_init, |
b4219952 HX |
290 | }; |
291 | ||
292 | MODULE_DESCRIPTION("Stateless NAT actions"); | |
293 | MODULE_LICENSE("GPL"); | |
294 | ||
295 | static int __init nat_init_module(void) | |
296 | { | |
4f1e9d89 | 297 | return tcf_register_action(&act_nat_ops, NAT_TAB_MASK); |
b4219952 HX |
298 | } |
299 | ||
300 | static void __exit nat_cleanup_module(void) | |
301 | { | |
302 | tcf_unregister_action(&act_nat_ops); | |
303 | } | |
304 | ||
305 | module_init(nat_init_module); | |
306 | module_exit(nat_cleanup_module); |