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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/pkt_cls.h>
25#include <net/icmp.h>
26#include <net/ip.h>
27#include <net/netlink.h>
28#include <net/tc_act/tc_nat.h>
29#include <net/tcp.h>
30#include <net/udp.h>
31
32
33static unsigned int nat_net_id;
34static struct tc_action_ops act_nat_ops;
35
36static const struct nla_policy nat_policy[TCA_NAT_MAX + 1] = {
37 [TCA_NAT_PARMS] = { .len = sizeof(struct tc_nat) },
38};
39
40static int tcf_nat_init(struct net *net, struct nlattr *nla, struct nlattr *est,
41 struct tc_action **a, int ovr, int bind,
42 bool rtnl_held, struct tcf_proto *tp,
43 struct netlink_ext_ack *extack)
44{
45 struct tc_action_net *tn = net_generic(net, nat_net_id);
46 struct nlattr *tb[TCA_NAT_MAX + 1];
47 struct tcf_chain *goto_ch = NULL;
48 struct tc_nat *parm;
49 int ret = 0, err;
50 struct tcf_nat *p;
51
52 if (nla == NULL)
53 return -EINVAL;
54
55 err = nla_parse_nested(tb, TCA_NAT_MAX, nla, nat_policy, NULL);
56 if (err < 0)
57 return err;
58
59 if (tb[TCA_NAT_PARMS] == NULL)
60 return -EINVAL;
61 parm = nla_data(tb[TCA_NAT_PARMS]);
62
63 err = tcf_idr_check_alloc(tn, &parm->index, a, bind);
64 if (!err) {
65 ret = tcf_idr_create(tn, parm->index, est, a,
66 &act_nat_ops, bind, false);
67 if (ret) {
68 tcf_idr_cleanup(tn, parm->index);
69 return ret;
70 }
71 ret = ACT_P_CREATED;
72 } else if (err > 0) {
73 if (bind)
74 return 0;
75 if (!ovr) {
76 tcf_idr_release(*a, bind);
77 return -EEXIST;
78 }
79 } else {
80 return err;
81 }
82 err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
83 if (err < 0)
84 goto release_idr;
85 p = to_tcf_nat(*a);
86
87 spin_lock_bh(&p->tcf_lock);
88 p->old_addr = parm->old_addr;
89 p->new_addr = parm->new_addr;
90 p->mask = parm->mask;
91 p->flags = parm->flags;
92
93 goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
94 spin_unlock_bh(&p->tcf_lock);
95 if (goto_ch)
96 tcf_chain_put_by_act(goto_ch);
97
98 if (ret == ACT_P_CREATED)
99 tcf_idr_insert(tn, *a);
100
101 return ret;
102release_idr:
103 tcf_idr_release(*a, bind);
104 return err;
105}
106
107static int tcf_nat_act(struct sk_buff *skb, const struct tc_action *a,
108 struct tcf_result *res)
109{
110 struct tcf_nat *p = to_tcf_nat(a);
111 struct iphdr *iph;
112 __be32 old_addr;
113 __be32 new_addr;
114 __be32 mask;
115 __be32 addr;
116 int egress;
117 int action;
118 int ihl;
119 int noff;
120
121 spin_lock(&p->tcf_lock);
122
123 tcf_lastuse_update(&p->tcf_tm);
124 old_addr = p->old_addr;
125 new_addr = p->new_addr;
126 mask = p->mask;
127 egress = p->flags & TCA_NAT_FLAG_EGRESS;
128 action = p->tcf_action;
129
130 bstats_update(&p->tcf_bstats, skb);
131
132 spin_unlock(&p->tcf_lock);
133
134 if (unlikely(action == TC_ACT_SHOT))
135 goto drop;
136
137 noff = skb_network_offset(skb);
138 if (!pskb_may_pull(skb, sizeof(*iph) + noff))
139 goto drop;
140
141 iph = ip_hdr(skb);
142
143 if (egress)
144 addr = iph->saddr;
145 else
146 addr = iph->daddr;
147
148 if (!((old_addr ^ addr) & mask)) {
149 if (skb_try_make_writable(skb, sizeof(*iph) + noff))
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_try_make_writable(skb, ihl + sizeof(*tcph) + noff))
178 goto drop;
179
180 tcph = (void *)(skb_network_header(skb) + ihl);
181 inet_proto_csum_replace4(&tcph->check, skb, addr, new_addr,
182 true);
183 break;
184 }
185 case IPPROTO_UDP:
186 {
187 struct udphdr *udph;
188
189 if (!pskb_may_pull(skb, ihl + sizeof(*udph) + noff) ||
190 skb_try_make_writable(skb, ihl + sizeof(*udph) + noff))
191 goto drop;
192
193 udph = (void *)(skb_network_header(skb) + ihl);
194 if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
195 inet_proto_csum_replace4(&udph->check, skb, addr,
196 new_addr, true);
197 if (!udph->check)
198 udph->check = CSUM_MANGLED_0;
199 }
200 break;
201 }
202 case IPPROTO_ICMP:
203 {
204 struct icmphdr *icmph;
205
206 if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + noff))
207 goto drop;
208
209 icmph = (void *)(skb_network_header(skb) + ihl);
210
211 if ((icmph->type != ICMP_DEST_UNREACH) &&
212 (icmph->type != ICMP_TIME_EXCEEDED) &&
213 (icmph->type != ICMP_PARAMETERPROB))
214 break;
215
216 if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + sizeof(*iph) +
217 noff))
218 goto drop;
219
220 icmph = (void *)(skb_network_header(skb) + ihl);
221 iph = (void *)(icmph + 1);
222 if (egress)
223 addr = iph->daddr;
224 else
225 addr = iph->saddr;
226
227 if ((old_addr ^ addr) & mask)
228 break;
229
230 if (skb_try_make_writable(skb, ihl + sizeof(*icmph) +
231 sizeof(*iph) + noff))
232 goto drop;
233
234 icmph = (void *)(skb_network_header(skb) + ihl);
235 iph = (void *)(icmph + 1);
236
237 new_addr &= mask;
238 new_addr |= addr & ~mask;
239
240
241 if (egress)
242 iph->daddr = new_addr;
243 else
244 iph->saddr = new_addr;
245
246 inet_proto_csum_replace4(&icmph->checksum, skb, addr, new_addr,
247 false);
248 break;
249 }
250 default:
251 break;
252 }
253
254out:
255 return action;
256
257drop:
258 spin_lock(&p->tcf_lock);
259 p->tcf_qstats.drops++;
260 spin_unlock(&p->tcf_lock);
261 return TC_ACT_SHOT;
262}
263
264static int tcf_nat_dump(struct sk_buff *skb, struct tc_action *a,
265 int bind, int ref)
266{
267 unsigned char *b = skb_tail_pointer(skb);
268 struct tcf_nat *p = to_tcf_nat(a);
269 struct tc_nat opt = {
270 .index = p->tcf_index,
271 .refcnt = refcount_read(&p->tcf_refcnt) - ref,
272 .bindcnt = atomic_read(&p->tcf_bindcnt) - bind,
273 };
274 struct tcf_t t;
275
276 spin_lock_bh(&p->tcf_lock);
277 opt.old_addr = p->old_addr;
278 opt.new_addr = p->new_addr;
279 opt.mask = p->mask;
280 opt.flags = p->flags;
281 opt.action = p->tcf_action;
282
283 if (nla_put(skb, TCA_NAT_PARMS, sizeof(opt), &opt))
284 goto nla_put_failure;
285
286 tcf_tm_dump(&t, &p->tcf_tm);
287 if (nla_put_64bit(skb, TCA_NAT_TM, sizeof(t), &t, TCA_NAT_PAD))
288 goto nla_put_failure;
289 spin_unlock_bh(&p->tcf_lock);
290
291 return skb->len;
292
293nla_put_failure:
294 spin_unlock_bh(&p->tcf_lock);
295 nlmsg_trim(skb, b);
296 return -1;
297}
298
299static int tcf_nat_walker(struct net *net, struct sk_buff *skb,
300 struct netlink_callback *cb, int type,
301 const struct tc_action_ops *ops,
302 struct netlink_ext_ack *extack)
303{
304 struct tc_action_net *tn = net_generic(net, nat_net_id);
305
306 return tcf_generic_walker(tn, skb, cb, type, ops, extack);
307}
308
309static int tcf_nat_search(struct net *net, struct tc_action **a, u32 index)
310{
311 struct tc_action_net *tn = net_generic(net, nat_net_id);
312
313 return tcf_idr_search(tn, a, index);
314}
315
316static struct tc_action_ops act_nat_ops = {
317 .kind = "nat",
318 .id = TCA_ID_NAT,
319 .owner = THIS_MODULE,
320 .act = tcf_nat_act,
321 .dump = tcf_nat_dump,
322 .init = tcf_nat_init,
323 .walk = tcf_nat_walker,
324 .lookup = tcf_nat_search,
325 .size = sizeof(struct tcf_nat),
326};
327
328static __net_init int nat_init_net(struct net *net)
329{
330 struct tc_action_net *tn = net_generic(net, nat_net_id);
331
332 return tc_action_net_init(tn, &act_nat_ops);
333}
334
335static void __net_exit nat_exit_net(struct list_head *net_list)
336{
337 tc_action_net_exit(net_list, nat_net_id);
338}
339
340static struct pernet_operations nat_net_ops = {
341 .init = nat_init_net,
342 .exit_batch = nat_exit_net,
343 .id = &nat_net_id,
344 .size = sizeof(struct tc_action_net),
345};
346
347MODULE_DESCRIPTION("Stateless NAT actions");
348MODULE_LICENSE("GPL");
349
350static int __init nat_init_module(void)
351{
352 return tcf_register_action(&act_nat_ops, &nat_net_ops);
353}
354
355static void __exit nat_cleanup_module(void)
356{
357 tcf_unregister_action(&act_nat_ops, &nat_net_ops);
358}
359
360module_init(nat_init_module);
361module_exit(nat_cleanup_module);
362
