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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 net *net, 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
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
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
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 if (nla_put(skb, TCA_NAT_PARMS, sizeof(opt), &opt))
288 goto nla_put_failure;
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);
292 if (nla_put(skb, TCA_NAT_TM, sizeof(t), &t))
293 goto nla_put_failure;
294
295 return skb->len;
296
297nla_put_failure:
298 nlmsg_trim(skb, b);
299 return -1;
300}
301
302static 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
316MODULE_DESCRIPTION("Stateless NAT actions");
317MODULE_LICENSE("GPL");
318
319static int __init nat_init_module(void)
320{
321 return tcf_register_action(&act_nat_ops);
322}
323
324static void __exit nat_cleanup_module(void)
325{
326 tcf_unregister_action(&act_nat_ops);
327}
328
329module_init(nat_init_module);
330module_exit(nat_cleanup_module);
331
