1
2
3
4
5
6
7
8
9
10#include <linux/types.h>
11#include <linux/module.h>
12#include <linux/skbuff.h>
13#include <linux/ipv6.h>
14#include <linux/netfilter.h>
15#include <linux/netfilter_ipv6.h>
16#include <net/secure_seq.h>
17#include <net/checksum.h>
18#include <net/ip6_checksum.h>
19#include <net/ip6_route.h>
20#include <net/ipv6.h>
21
22#include <net/netfilter/nf_conntrack_core.h>
23#include <net/netfilter/nf_conntrack.h>
24#include <net/netfilter/nf_nat_core.h>
25#include <net/netfilter/nf_nat_l3proto.h>
26#include <net/netfilter/nf_nat_l4proto.h>
27
28static const struct nf_nat_l3proto nf_nat_l3proto_ipv6;
29
30#ifdef CONFIG_XFRM
31static void nf_nat_ipv6_decode_session(struct sk_buff *skb,
32 const struct nf_conn *ct,
33 enum ip_conntrack_dir dir,
34 unsigned long statusbit,
35 struct flowi *fl)
36{
37 const struct nf_conntrack_tuple *t = &ct->tuplehash[dir].tuple;
38 struct flowi6 *fl6 = &fl->u.ip6;
39
40 if (ct->status & statusbit) {
41 fl6->daddr = t->dst.u3.in6;
42 if (t->dst.protonum == IPPROTO_TCP ||
43 t->dst.protonum == IPPROTO_UDP ||
44 t->dst.protonum == IPPROTO_UDPLITE ||
45 t->dst.protonum == IPPROTO_DCCP ||
46 t->dst.protonum == IPPROTO_SCTP)
47 fl6->fl6_dport = t->dst.u.all;
48 }
49
50 statusbit ^= IPS_NAT_MASK;
51
52 if (ct->status & statusbit) {
53 fl6->saddr = t->src.u3.in6;
54 if (t->dst.protonum == IPPROTO_TCP ||
55 t->dst.protonum == IPPROTO_UDP ||
56 t->dst.protonum == IPPROTO_UDPLITE ||
57 t->dst.protonum == IPPROTO_DCCP ||
58 t->dst.protonum == IPPROTO_SCTP)
59 fl6->fl6_sport = t->src.u.all;
60 }
61}
62#endif
63
64static bool nf_nat_ipv6_in_range(const struct nf_conntrack_tuple *t,
65 const struct nf_nat_range *range)
66{
67 return ipv6_addr_cmp(&t->src.u3.in6, &range->min_addr.in6) >= 0 &&
68 ipv6_addr_cmp(&t->src.u3.in6, &range->max_addr.in6) <= 0;
69}
70
71static u32 nf_nat_ipv6_secure_port(const struct nf_conntrack_tuple *t,
72 __be16 dport)
73{
74 return secure_ipv6_port_ephemeral(t->src.u3.ip6, t->dst.u3.ip6, dport);
75}
76
77static bool nf_nat_ipv6_manip_pkt(struct sk_buff *skb,
78 unsigned int iphdroff,
79 const struct nf_nat_l4proto *l4proto,
80 const struct nf_conntrack_tuple *target,
81 enum nf_nat_manip_type maniptype)
82{
83 struct ipv6hdr *ipv6h;
84 __be16 frag_off;
85 int hdroff;
86 u8 nexthdr;
87
88 if (!skb_make_writable(skb, iphdroff + sizeof(*ipv6h)))
89 return false;
90
91 ipv6h = (void *)skb->data + iphdroff;
92 nexthdr = ipv6h->nexthdr;
93 hdroff = ipv6_skip_exthdr(skb, iphdroff + sizeof(*ipv6h),
94 &nexthdr, &frag_off);
95 if (hdroff < 0)
96 goto manip_addr;
97
98 if ((frag_off & htons(~0x7)) == 0 &&
99 !l4proto->manip_pkt(skb, &nf_nat_l3proto_ipv6, iphdroff, hdroff,
100 target, maniptype))
101 return false;
102manip_addr:
103 if (maniptype == NF_NAT_MANIP_SRC)
104 ipv6h->saddr = target->src.u3.in6;
105 else
106 ipv6h->daddr = target->dst.u3.in6;
107
108 return true;
109}
110
111static void nf_nat_ipv6_csum_update(struct sk_buff *skb,
112 unsigned int iphdroff, __sum16 *check,
113 const struct nf_conntrack_tuple *t,
114 enum nf_nat_manip_type maniptype)
115{
116 const struct ipv6hdr *ipv6h = (struct ipv6hdr *)(skb->data + iphdroff);
117 const struct in6_addr *oldip, *newip;
118
119 if (maniptype == NF_NAT_MANIP_SRC) {
120 oldip = &ipv6h->saddr;
121 newip = &t->src.u3.in6;
122 } else {
123 oldip = &ipv6h->daddr;
124 newip = &t->dst.u3.in6;
125 }
126 inet_proto_csum_replace16(check, skb, oldip->s6_addr32,
127 newip->s6_addr32, 1);
128}
129
130static void nf_nat_ipv6_csum_recalc(struct sk_buff *skb,
131 u8 proto, void *data, __sum16 *check,
132 int datalen, int oldlen)
133{
134 const struct ipv6hdr *ipv6h = ipv6_hdr(skb);
135 struct rt6_info *rt = (struct rt6_info *)skb_dst(skb);
136
137 if (skb->ip_summed != CHECKSUM_PARTIAL) {
138 if (!(rt->rt6i_flags & RTF_LOCAL) &&
139 (!skb->dev || skb->dev->features & NETIF_F_V6_CSUM)) {
140 skb->ip_summed = CHECKSUM_PARTIAL;
141 skb->csum_start = skb_headroom(skb) +
142 skb_network_offset(skb) +
143 (data - (void *)skb->data);
144 skb->csum_offset = (void *)check - data;
145 *check = ~csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr,
146 datalen, proto, 0);
147 } else {
148 *check = 0;
149 *check = csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr,
150 datalen, proto,
151 csum_partial(data, datalen,
152 0));
153 if (proto == IPPROTO_UDP && !*check)
154 *check = CSUM_MANGLED_0;
155 }
156 } else
157 inet_proto_csum_replace2(check, skb,
158 htons(oldlen), htons(datalen), 1);
159}
160
161#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
162static int nf_nat_ipv6_nlattr_to_range(struct nlattr *tb[],
163 struct nf_nat_range *range)
164{
165 if (tb[CTA_NAT_V6_MINIP]) {
166 nla_memcpy(&range->min_addr.ip6, tb[CTA_NAT_V6_MINIP],
167 sizeof(struct in6_addr));
168 range->flags |= NF_NAT_RANGE_MAP_IPS;
169 }
170
171 if (tb[CTA_NAT_V6_MAXIP])
172 nla_memcpy(&range->max_addr.ip6, tb[CTA_NAT_V6_MAXIP],
173 sizeof(struct in6_addr));
174 else
175 range->max_addr = range->min_addr;
176
177 return 0;
178}
179#endif
180
181static const struct nf_nat_l3proto nf_nat_l3proto_ipv6 = {
182 .l3proto = NFPROTO_IPV6,
183 .secure_port = nf_nat_ipv6_secure_port,
184 .in_range = nf_nat_ipv6_in_range,
185 .manip_pkt = nf_nat_ipv6_manip_pkt,
186 .csum_update = nf_nat_ipv6_csum_update,
187 .csum_recalc = nf_nat_ipv6_csum_recalc,
188#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
189 .nlattr_to_range = nf_nat_ipv6_nlattr_to_range,
190#endif
191#ifdef CONFIG_XFRM
192 .decode_session = nf_nat_ipv6_decode_session,
193#endif
194};
195
196int nf_nat_icmpv6_reply_translation(struct sk_buff *skb,
197 struct nf_conn *ct,
198 enum ip_conntrack_info ctinfo,
199 unsigned int hooknum,
200 unsigned int hdrlen)
201{
202 struct {
203 struct icmp6hdr icmp6;
204 struct ipv6hdr ip6;
205 } *inside;
206 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
207 enum nf_nat_manip_type manip = HOOK2MANIP(hooknum);
208 const struct nf_nat_l4proto *l4proto;
209 struct nf_conntrack_tuple target;
210 unsigned long statusbit;
211
212 NF_CT_ASSERT(ctinfo == IP_CT_RELATED || ctinfo == IP_CT_RELATED_REPLY);
213
214 if (!skb_make_writable(skb, hdrlen + sizeof(*inside)))
215 return 0;
216 if (nf_ip6_checksum(skb, hooknum, hdrlen, IPPROTO_ICMPV6))
217 return 0;
218
219 inside = (void *)skb->data + hdrlen;
220 if (inside->icmp6.icmp6_type == NDISC_REDIRECT) {
221 if ((ct->status & IPS_NAT_DONE_MASK) != IPS_NAT_DONE_MASK)
222 return 0;
223 if (ct->status & IPS_NAT_MASK)
224 return 0;
225 }
226
227 if (manip == NF_NAT_MANIP_SRC)
228 statusbit = IPS_SRC_NAT;
229 else
230 statusbit = IPS_DST_NAT;
231
232
233 if (dir == IP_CT_DIR_REPLY)
234 statusbit ^= IPS_NAT_MASK;
235
236 if (!(ct->status & statusbit))
237 return 1;
238
239 l4proto = __nf_nat_l4proto_find(NFPROTO_IPV6, inside->ip6.nexthdr);
240 if (!nf_nat_ipv6_manip_pkt(skb, hdrlen + sizeof(inside->icmp6),
241 l4proto, &ct->tuplehash[!dir].tuple, !manip))
242 return 0;
243
244 if (skb->ip_summed != CHECKSUM_PARTIAL) {
245 struct ipv6hdr *ipv6h = ipv6_hdr(skb);
246 inside = (void *)skb->data + hdrlen;
247 inside->icmp6.icmp6_cksum = 0;
248 inside->icmp6.icmp6_cksum =
249 csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr,
250 skb->len - hdrlen, IPPROTO_ICMPV6,
251 csum_partial(&inside->icmp6,
252 skb->len - hdrlen, 0));
253 }
254
255 nf_ct_invert_tuplepr(&target, &ct->tuplehash[!dir].tuple);
256 l4proto = __nf_nat_l4proto_find(NFPROTO_IPV6, IPPROTO_ICMPV6);
257 if (!nf_nat_ipv6_manip_pkt(skb, 0, l4proto, &target, manip))
258 return 0;
259
260 return 1;
261}
262EXPORT_SYMBOL_GPL(nf_nat_icmpv6_reply_translation);
263
264unsigned int
265nf_nat_ipv6_fn(const struct nf_hook_ops *ops, struct sk_buff *skb,
266 const struct nf_hook_state *state,
267 unsigned int (*do_chain)(const struct nf_hook_ops *ops,
268 struct sk_buff *skb,
269 const struct nf_hook_state *state,
270 struct nf_conn *ct))
271{
272 struct nf_conn *ct;
273 enum ip_conntrack_info ctinfo;
274 struct nf_conn_nat *nat;
275 enum nf_nat_manip_type maniptype = HOOK2MANIP(ops->hooknum);
276 __be16 frag_off;
277 int hdrlen;
278 u8 nexthdr;
279
280 ct = nf_ct_get(skb, &ctinfo);
281
282
283
284
285
286 if (!ct)
287 return NF_ACCEPT;
288
289
290 if (nf_ct_is_untracked(ct))
291 return NF_ACCEPT;
292
293 nat = nf_ct_nat_ext_add(ct);
294 if (nat == NULL)
295 return NF_ACCEPT;
296
297 switch (ctinfo) {
298 case IP_CT_RELATED:
299 case IP_CT_RELATED_REPLY:
300 nexthdr = ipv6_hdr(skb)->nexthdr;
301 hdrlen = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr),
302 &nexthdr, &frag_off);
303
304 if (hdrlen >= 0 && nexthdr == IPPROTO_ICMPV6) {
305 if (!nf_nat_icmpv6_reply_translation(skb, ct, ctinfo,
306 ops->hooknum,
307 hdrlen))
308 return NF_DROP;
309 else
310 return NF_ACCEPT;
311 }
312
313 case IP_CT_NEW:
314
315
316
317 if (!nf_nat_initialized(ct, maniptype)) {
318 unsigned int ret;
319
320 ret = do_chain(ops, skb, state, ct);
321 if (ret != NF_ACCEPT)
322 return ret;
323
324 if (nf_nat_initialized(ct, HOOK2MANIP(ops->hooknum)))
325 break;
326
327 ret = nf_nat_alloc_null_binding(ct, ops->hooknum);
328 if (ret != NF_ACCEPT)
329 return ret;
330 } else {
331 pr_debug("Already setup manip %s for ct %p\n",
332 maniptype == NF_NAT_MANIP_SRC ? "SRC" : "DST",
333 ct);
334 if (nf_nat_oif_changed(ops->hooknum, ctinfo, nat, state->out))
335 goto oif_changed;
336 }
337 break;
338
339 default:
340
341 NF_CT_ASSERT(ctinfo == IP_CT_ESTABLISHED ||
342 ctinfo == IP_CT_ESTABLISHED_REPLY);
343 if (nf_nat_oif_changed(ops->hooknum, ctinfo, nat, state->out))
344 goto oif_changed;
345 }
346
347 return nf_nat_packet(ct, ctinfo, ops->hooknum, skb);
348
349oif_changed:
350 nf_ct_kill_acct(ct, ctinfo, skb);
351 return NF_DROP;
352}
353EXPORT_SYMBOL_GPL(nf_nat_ipv6_fn);
354
355unsigned int
356nf_nat_ipv6_in(const struct nf_hook_ops *ops, struct sk_buff *skb,
357 const struct nf_hook_state *state,
358 unsigned int (*do_chain)(const struct nf_hook_ops *ops,
359 struct sk_buff *skb,
360 const struct nf_hook_state *state,
361 struct nf_conn *ct))
362{
363 unsigned int ret;
364 struct in6_addr daddr = ipv6_hdr(skb)->daddr;
365
366 ret = nf_nat_ipv6_fn(ops, skb, state, do_chain);
367 if (ret != NF_DROP && ret != NF_STOLEN &&
368 ipv6_addr_cmp(&daddr, &ipv6_hdr(skb)->daddr))
369 skb_dst_drop(skb);
370
371 return ret;
372}
373EXPORT_SYMBOL_GPL(nf_nat_ipv6_in);
374
375unsigned int
376nf_nat_ipv6_out(const struct nf_hook_ops *ops, struct sk_buff *skb,
377 const struct nf_hook_state *state,
378 unsigned int (*do_chain)(const struct nf_hook_ops *ops,
379 struct sk_buff *skb,
380 const struct nf_hook_state *state,
381 struct nf_conn *ct))
382{
383#ifdef CONFIG_XFRM
384 const struct nf_conn *ct;
385 enum ip_conntrack_info ctinfo;
386 int err;
387#endif
388 unsigned int ret;
389
390
391 if (skb->len < sizeof(struct ipv6hdr))
392 return NF_ACCEPT;
393
394 ret = nf_nat_ipv6_fn(ops, skb, state, do_chain);
395#ifdef CONFIG_XFRM
396 if (ret != NF_DROP && ret != NF_STOLEN &&
397 !(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
398 (ct = nf_ct_get(skb, &ctinfo)) != NULL) {
399 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
400
401 if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3,
402 &ct->tuplehash[!dir].tuple.dst.u3) ||
403 (ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMPV6 &&
404 ct->tuplehash[dir].tuple.src.u.all !=
405 ct->tuplehash[!dir].tuple.dst.u.all)) {
406 err = nf_xfrm_me_harder(skb, AF_INET6);
407 if (err < 0)
408 ret = NF_DROP_ERR(err);
409 }
410 }
411#endif
412 return ret;
413}
414EXPORT_SYMBOL_GPL(nf_nat_ipv6_out);
415
416unsigned int
417nf_nat_ipv6_local_fn(const struct nf_hook_ops *ops, struct sk_buff *skb,
418 const struct nf_hook_state *state,
419 unsigned int (*do_chain)(const struct nf_hook_ops *ops,
420 struct sk_buff *skb,
421 const struct nf_hook_state *state,
422 struct nf_conn *ct))
423{
424 const struct nf_conn *ct;
425 enum ip_conntrack_info ctinfo;
426 unsigned int ret;
427 int err;
428
429
430 if (skb->len < sizeof(struct ipv6hdr))
431 return NF_ACCEPT;
432
433 ret = nf_nat_ipv6_fn(ops, skb, state, do_chain);
434 if (ret != NF_DROP && ret != NF_STOLEN &&
435 (ct = nf_ct_get(skb, &ctinfo)) != NULL) {
436 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
437
438 if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.dst.u3,
439 &ct->tuplehash[!dir].tuple.src.u3)) {
440 err = ip6_route_me_harder(skb);
441 if (err < 0)
442 ret = NF_DROP_ERR(err);
443 }
444#ifdef CONFIG_XFRM
445 else if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
446 ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMPV6 &&
447 ct->tuplehash[dir].tuple.dst.u.all !=
448 ct->tuplehash[!dir].tuple.src.u.all) {
449 err = nf_xfrm_me_harder(skb, AF_INET6);
450 if (err < 0)
451 ret = NF_DROP_ERR(err);
452 }
453#endif
454 }
455 return ret;
456}
457EXPORT_SYMBOL_GPL(nf_nat_ipv6_local_fn);
458
459static int __init nf_nat_l3proto_ipv6_init(void)
460{
461 int err;
462
463 err = nf_nat_l4proto_register(NFPROTO_IPV6, &nf_nat_l4proto_icmpv6);
464 if (err < 0)
465 goto err1;
466 err = nf_nat_l3proto_register(&nf_nat_l3proto_ipv6);
467 if (err < 0)
468 goto err2;
469 return err;
470
471err2:
472 nf_nat_l4proto_unregister(NFPROTO_IPV6, &nf_nat_l4proto_icmpv6);
473err1:
474 return err;
475}
476
477static void __exit nf_nat_l3proto_ipv6_exit(void)
478{
479 nf_nat_l3proto_unregister(&nf_nat_l3proto_ipv6);
480 nf_nat_l4proto_unregister(NFPROTO_IPV6, &nf_nat_l4proto_icmpv6);
481}
482
483MODULE_LICENSE("GPL");
484MODULE_ALIAS("nf-nat-" __stringify(AF_INET6));
485
486module_init(nf_nat_l3proto_ipv6_init);
487module_exit(nf_nat_l3proto_ipv6_exit);
488
