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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
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
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
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
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);
343