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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
33static struct tcf_common *tcf_nat_ht[NAT_TAB_MASK + 1];
34static u32 nat_idx_gen;
35static DEFINE_RWLOCK(nat_lock);
36
37static struct tcf_hashinfo nat_hash_info = {
38 .htab = tcf_nat_ht,
39 .hmask = NAT_TAB_MASK,
40 .lock = &nat_lock,
41};
42
43static const struct nla_policy nat_policy[TCA_NAT_MAX + 1] = {
44 [TCA_NAT_PARMS] = { .len = sizeof(struct tc_nat) },
45};
46
47static int tcf_nat_init(struct nlattr *nla, struct nlattr *est,
48 struct tc_action *a, int ovr, int bind)
49{
50 struct nlattr *tb[TCA_NAT_MAX + 1];
51 struct tc_nat *parm;
52 int ret = 0, err;
53 struct tcf_nat *p;
54 struct tcf_common *pc;
55
56 if (nla == NULL)
57 return -EINVAL;
58
59 err = nla_parse_nested(tb, TCA_NAT_MAX, nla, nat_policy);
60 if (err < 0)
61 return err;
62
63 if (tb[TCA_NAT_PARMS] == NULL)
64 return -EINVAL;
65 parm = nla_data(tb[TCA_NAT_PARMS]);
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);
71 if (IS_ERR(pc))
72 return PTR_ERR(pc);
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
98static 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
105static int tcf_nat(struct sk_buff *skb, const struct tc_action *a,
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;
117 int noff;
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
128 bstats_update(&p->tcf_bstats, skb);
129
130 spin_unlock(&p->tcf_lock);
131
132 if (unlikely(action == TC_ACT_SHOT))
133 goto drop;
134
135 noff = skb_network_offset(skb);
136 if (!pskb_may_pull(skb, sizeof(*iph) + noff))
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) &&
148 !skb_clone_writable(skb, sizeof(*iph) + noff) &&
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
162 csum_replace4(&iph->check, addr, new_addr);
163 } else if ((iph->frag_off & htons(IP_OFFSET)) ||
164 iph->protocol != IPPROTO_ICMP) {
165 goto out;
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
176 if (!pskb_may_pull(skb, ihl + sizeof(*tcph) + noff) ||
177 (skb_cloned(skb) &&
178 !skb_clone_writable(skb, ihl + sizeof(*tcph) + noff) &&
179 pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
180 goto drop;
181
182 tcph = (void *)(skb_network_header(skb) + ihl);
183 inet_proto_csum_replace4(&tcph->check, skb, addr, new_addr, 1);
184 break;
185 }
186 case IPPROTO_UDP:
187 {
188 struct udphdr *udph;
189
190 if (!pskb_may_pull(skb, ihl + sizeof(*udph) + noff) ||
191 (skb_cloned(skb) &&
192 !skb_clone_writable(skb, ihl + sizeof(*udph) + noff) &&
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) {
198 inet_proto_csum_replace4(&udph->check, skb, addr,
199 new_addr, 1);
200 if (!udph->check)
201 udph->check = CSUM_MANGLED_0;
202 }
203 break;
204 }
205 case IPPROTO_ICMP:
206 {
207 struct icmphdr *icmph;
208
209 if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + noff))
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
219 if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + sizeof(*iph) +
220 noff))
221 goto drop;
222
223 icmph = (void *)(skb_network_header(skb) + ihl);
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) &&
234 !skb_clone_writable(skb, ihl + sizeof(*icmph) +
235 sizeof(*iph) + noff) &&
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
251 inet_proto_csum_replace4(&icmph->checksum, skb, addr, new_addr,
252 0);
253 break;
254 }
255 default:
256 break;
257 }
258
259out:
260 return action;
261
262drop:
263 spin_lock(&p->tcf_lock);
264 p->tcf_qstats.drops++;
265 spin_unlock(&p->tcf_lock);
266 return TC_ACT_SHOT;
267}
268
269static 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;
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 };
285 struct tcf_t t;
286
287 NLA_PUT(skb, TCA_NAT_PARMS, sizeof(opt), &opt);
288 t.install = jiffies_to_clock_t(jiffies - p->tcf_tm.install);
289 t.lastuse = jiffies_to_clock_t(jiffies - p->tcf_tm.lastuse);
290 t.expires = jiffies_to_clock_t(p->tcf_tm.expires);
291 NLA_PUT(skb, TCA_NAT_TM, sizeof(t), &t);
292
293 return skb->len;
294
295nla_put_failure:
296 nlmsg_trim(skb, b);
297 return -1;
298}
299
300static struct tc_action_ops act_nat_ops = {
301 .kind = "nat",
302 .hinfo = &nat_hash_info,
303 .type = TCA_ACT_NAT,
304 .capab = TCA_CAP_NONE,
305 .owner = THIS_MODULE,
306 .act = tcf_nat,
307 .dump = tcf_nat_dump,
308 .cleanup = tcf_nat_cleanup,
309 .lookup = tcf_hash_search,
310 .init = tcf_nat_init,
311 .walk = tcf_generic_walker
312};
313
314MODULE_DESCRIPTION("Stateless NAT actions");
315MODULE_LICENSE("GPL");
316
317static int __init nat_init_module(void)
318{
319 return tcf_register_action(&act_nat_ops);
320}
321
322static void __exit nat_cleanup_module(void)
323{
324 tcf_unregister_action(&act_nat_ops);
325}
326
327module_init(nat_init_module);
328module_exit(nat_cleanup_module);
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
32static unsigned int nat_net_id;
33static struct tc_action_ops act_nat_ops;
34
35static const struct nla_policy nat_policy[TCA_NAT_MAX + 1] = {
36 [TCA_NAT_PARMS] = { .len = sizeof(struct tc_nat) },
37};
38
39static int tcf_nat_init(struct net *net, struct nlattr *nla, struct nlattr *est,
40 struct tc_action **a, int ovr, int bind,
41 struct netlink_ext_ack *extack)
42{
43 struct tc_action_net *tn = net_generic(net, nat_net_id);
44 struct nlattr *tb[TCA_NAT_MAX + 1];
45 struct tc_nat *parm;
46 int ret = 0, err;
47 struct tcf_nat *p;
48
49 if (nla == NULL)
50 return -EINVAL;
51
52 err = nla_parse_nested(tb, TCA_NAT_MAX, nla, nat_policy, NULL);
53 if (err < 0)
54 return err;
55
56 if (tb[TCA_NAT_PARMS] == NULL)
57 return -EINVAL;
58 parm = nla_data(tb[TCA_NAT_PARMS]);
59
60 if (!tcf_idr_check(tn, parm->index, a, bind)) {
61 ret = tcf_idr_create(tn, parm->index, est, a,
62 &act_nat_ops, bind, false);
63 if (ret)
64 return ret;
65 ret = ACT_P_CREATED;
66 } else {
67 if (bind)
68 return 0;
69 tcf_idr_release(*a, bind);
70 if (!ovr)
71 return -EEXIST;
72 }
73 p = to_tcf_nat(*a);
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)
85 tcf_idr_insert(tn, *a);
86
87 return ret;
88}
89
90static int tcf_nat(struct sk_buff *skb, const struct tc_action *a,
91 struct tcf_result *res)
92{
93 struct tcf_nat *p = to_tcf_nat(a);
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;
102 int noff;
103
104 spin_lock(&p->tcf_lock);
105
106 tcf_lastuse_update(&p->tcf_tm);
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
113 bstats_update(&p->tcf_bstats, skb);
114
115 spin_unlock(&p->tcf_lock);
116
117 if (unlikely(action == TC_ACT_SHOT))
118 goto drop;
119
120 noff = skb_network_offset(skb);
121 if (!pskb_may_pull(skb, sizeof(*iph) + noff))
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)) {
132 if (skb_try_make_writable(skb, sizeof(*iph) + noff))
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
145 csum_replace4(&iph->check, addr, new_addr);
146 } else if ((iph->frag_off & htons(IP_OFFSET)) ||
147 iph->protocol != IPPROTO_ICMP) {
148 goto out;
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
159 if (!pskb_may_pull(skb, ihl + sizeof(*tcph) + noff) ||
160 skb_try_make_writable(skb, ihl + sizeof(*tcph) + noff))
161 goto drop;
162
163 tcph = (void *)(skb_network_header(skb) + ihl);
164 inet_proto_csum_replace4(&tcph->check, skb, addr, new_addr,
165 true);
166 break;
167 }
168 case IPPROTO_UDP:
169 {
170 struct udphdr *udph;
171
172 if (!pskb_may_pull(skb, ihl + sizeof(*udph) + noff) ||
173 skb_try_make_writable(skb, ihl + sizeof(*udph) + noff))
174 goto drop;
175
176 udph = (void *)(skb_network_header(skb) + ihl);
177 if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
178 inet_proto_csum_replace4(&udph->check, skb, addr,
179 new_addr, true);
180 if (!udph->check)
181 udph->check = CSUM_MANGLED_0;
182 }
183 break;
184 }
185 case IPPROTO_ICMP:
186 {
187 struct icmphdr *icmph;
188
189 if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + noff))
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
199 if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + sizeof(*iph) +
200 noff))
201 goto drop;
202
203 icmph = (void *)(skb_network_header(skb) + ihl);
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
213 if (skb_try_make_writable(skb, ihl + sizeof(*icmph) +
214 sizeof(*iph) + noff))
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
229 inet_proto_csum_replace4(&icmph->checksum, skb, addr, new_addr,
230 false);
231 break;
232 }
233 default:
234 break;
235 }
236
237out:
238 return action;
239
240drop:
241 spin_lock(&p->tcf_lock);
242 p->tcf_qstats.drops++;
243 spin_unlock(&p->tcf_lock);
244 return TC_ACT_SHOT;
245}
246
247static 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 = to_tcf_nat(a);
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 };
263 struct tcf_t t;
264
265 if (nla_put(skb, TCA_NAT_PARMS, sizeof(opt), &opt))
266 goto nla_put_failure;
267
268 tcf_tm_dump(&t, &p->tcf_tm);
269 if (nla_put_64bit(skb, TCA_NAT_TM, sizeof(t), &t, TCA_NAT_PAD))
270 goto nla_put_failure;
271
272 return skb->len;
273
274nla_put_failure:
275 nlmsg_trim(skb, b);
276 return -1;
277}
278
279static int tcf_nat_walker(struct net *net, struct sk_buff *skb,
280 struct netlink_callback *cb, int type,
281 const struct tc_action_ops *ops,
282 struct netlink_ext_ack *extack)
283{
284 struct tc_action_net *tn = net_generic(net, nat_net_id);
285
286 return tcf_generic_walker(tn, skb, cb, type, ops, extack);
287}
288
289static int tcf_nat_search(struct net *net, struct tc_action **a, u32 index,
290 struct netlink_ext_ack *extack)
291{
292 struct tc_action_net *tn = net_generic(net, nat_net_id);
293
294 return tcf_idr_search(tn, a, index);
295}
296
297static struct tc_action_ops act_nat_ops = {
298 .kind = "nat",
299 .type = TCA_ACT_NAT,
300 .owner = THIS_MODULE,
301 .act = tcf_nat,
302 .dump = tcf_nat_dump,
303 .init = tcf_nat_init,
304 .walk = tcf_nat_walker,
305 .lookup = tcf_nat_search,
306 .size = sizeof(struct tcf_nat),
307};
308
309static __net_init int nat_init_net(struct net *net)
310{
311 struct tc_action_net *tn = net_generic(net, nat_net_id);
312
313 return tc_action_net_init(tn, &act_nat_ops);
314}
315
316static void __net_exit nat_exit_net(struct list_head *net_list)
317{
318 tc_action_net_exit(net_list, nat_net_id);
319}
320
321static struct pernet_operations nat_net_ops = {
322 .init = nat_init_net,
323 .exit_batch = nat_exit_net,
324 .id = &nat_net_id,
325 .size = sizeof(struct tc_action_net),
326};
327
328MODULE_DESCRIPTION("Stateless NAT actions");
329MODULE_LICENSE("GPL");
330
331static int __init nat_init_module(void)
332{
333 return tcf_register_action(&act_nat_ops, &nat_net_ops);
334}
335
336static void __exit nat_cleanup_module(void)
337{
338 tcf_unregister_action(&act_nat_ops, &nat_net_ops);
339}
340
341module_init(nat_init_module);
342module_exit(nat_cleanup_module);