1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Anycast support for IPv6
4 * Linux INET6 implementation
5 *
6 * Authors:
7 * David L Stevens (dlstevens@us.ibm.com)
8 *
9 * based heavily on net/ipv6/mcast.c
10 */
11
12 #include <linux/capability.h>
13 #include <linux/module.h>
14 #include <linux/errno.h>
15 #include <linux/types.h>
16 #include <linux/random.h>
17 #include <linux/string.h>
18 #include <linux/socket.h>
19 #include <linux/sockios.h>
20 #include <linux/net.h>
21 #include <linux/in6.h>
22 #include <linux/netdevice.h>
23 #include <linux/if_arp.h>
24 #include <linux/route.h>
25 #include <linux/init.h>
26 #include <linux/proc_fs.h>
27 #include <linux/seq_file.h>
28 #include <linux/slab.h>
29
30 #include <net/net_namespace.h>
31 #include <net/sock.h>
32 #include <net/snmp.h>
33
34 #include <net/ipv6.h>
35 #include <net/protocol.h>
36 #include <net/if_inet6.h>
37 #include <net/ndisc.h>
38 #include <net/addrconf.h>
39 #include <net/ip6_route.h>
40
41 #include <net/checksum.h>
42
43 #define IN6_ADDR_HSIZE_SHIFT 8
44 #define IN6_ADDR_HSIZE BIT(IN6_ADDR_HSIZE_SHIFT)
45 /* anycast address hash table
46 */
47 static struct hlist_head inet6_acaddr_lst[IN6_ADDR_HSIZE];
48 static DEFINE_SPINLOCK(acaddr_hash_lock);
49
50 static int ipv6_dev_ac_dec(struct net_device *dev, const struct in6_addr *addr);
51
52 static u32 inet6_acaddr_hash(struct net *net, const struct in6_addr *addr)
53 {
54 u32 val = ipv6_addr_hash(addr) ^ net_hash_mix(net);
55
56 return hash_32(val, IN6_ADDR_HSIZE_SHIFT);
57 }
58
59 /*
60 * socket join an anycast group
61 */
62
63 int ipv6_sock_ac_join(struct sock *sk, int ifindex, const struct in6_addr *addr)
64 {
65 struct ipv6_pinfo *np = inet6_sk(sk);
66 struct net_device *dev = NULL;
67 struct inet6_dev *idev;
68 struct ipv6_ac_socklist *pac;
69 struct net *net = sock_net(sk);
70 int ishost = !net->ipv6.devconf_all->forwarding;
71 int err = 0;
72
73 ASSERT_RTNL();
74
75 if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
76 return -EPERM;
77 if (ipv6_addr_is_multicast(addr))
78 return -EINVAL;
79
80 if (ifindex)
81 dev = __dev_get_by_index(net, ifindex);
82
83 if (ipv6_chk_addr_and_flags(net, addr, dev, true, 0, IFA_F_TENTATIVE))
84 return -EINVAL;
85
86 pac = sock_kmalloc(sk, sizeof(struct ipv6_ac_socklist), GFP_KERNEL);
87 if (!pac)
88 return -ENOMEM;
89 pac->acl_next = NULL;
90 pac->acl_addr = *addr;
91
92 if (ifindex == 0) {
93 struct rt6_info *rt;
94
95 rt = rt6_lookup(net, addr, NULL, 0, NULL, 0);
96 if (rt) {
97 dev = rt->dst.dev;
98 ip6_rt_put(rt);
99 } else if (ishost) {
100 err = -EADDRNOTAVAIL;
101 goto error;
102 } else {
103 /* router, no matching interface: just pick one */
104 dev = __dev_get_by_flags(net, IFF_UP,
105 IFF_UP | IFF_LOOPBACK);
106 }
107 }
108
109 if (!dev) {
110 err = -ENODEV;
111 goto error;
112 }
113
114 idev = __in6_dev_get(dev);
115 if (!idev) {
116 if (ifindex)
117 err = -ENODEV;
118 else
119 err = -EADDRNOTAVAIL;
120 goto error;
121 }
122 /* reset ishost, now that we have a specific device */
123 ishost = !idev->cnf.forwarding;
124
125 pac->acl_ifindex = dev->ifindex;
126
127 /* XXX
128 * For hosts, allow link-local or matching prefix anycasts.
129 * This obviates the need for propagating anycast routes while
130 * still allowing some non-router anycast participation.
131 */
132 if (!ipv6_chk_prefix(addr, dev)) {
133 if (ishost)
134 err = -EADDRNOTAVAIL;
135 if (err)
136 goto error;
137 }
138
139 err = __ipv6_dev_ac_inc(idev, addr);
140 if (!err) {
141 pac->acl_next = np->ipv6_ac_list;
142 np->ipv6_ac_list = pac;
143 pac = NULL;
144 }
145
146 error:
147 if (pac)
148 sock_kfree_s(sk, pac, sizeof(*pac));
149 return err;
150 }
151
152 /*
153 * socket leave an anycast group
154 */
155 int ipv6_sock_ac_drop(struct sock *sk, int ifindex, const struct in6_addr *addr)
156 {
157 struct ipv6_pinfo *np = inet6_sk(sk);
158 struct net_device *dev;
159 struct ipv6_ac_socklist *pac, *prev_pac;
160 struct net *net = sock_net(sk);
161
162 ASSERT_RTNL();
163
164 prev_pac = NULL;
165 for (pac = np->ipv6_ac_list; pac; pac = pac->acl_next) {
166 if ((ifindex == 0 || pac->acl_ifindex == ifindex) &&
167 ipv6_addr_equal(&pac->acl_addr, addr))
168 break;
169 prev_pac = pac;
170 }
171 if (!pac)
172 return -ENOENT;
173 if (prev_pac)
174 prev_pac->acl_next = pac->acl_next;
175 else
176 np->ipv6_ac_list = pac->acl_next;
177
178 dev = __dev_get_by_index(net, pac->acl_ifindex);
179 if (dev)
180 ipv6_dev_ac_dec(dev, &pac->acl_addr);
181
182 sock_kfree_s(sk, pac, sizeof(*pac));
183 return 0;
184 }
185
186 void ipv6_sock_ac_close(struct sock *sk)
187 {
188 struct ipv6_pinfo *np = inet6_sk(sk);
189 struct net_device *dev = NULL;
190 struct ipv6_ac_socklist *pac;
191 struct net *net = sock_net(sk);
192 int prev_index;
193
194 if (!np->ipv6_ac_list)
195 return;
196
197 rtnl_lock();
198 pac = np->ipv6_ac_list;
199 np->ipv6_ac_list = NULL;
200
201 prev_index = 0;
202 while (pac) {
203 struct ipv6_ac_socklist *next = pac->acl_next;
204
205 if (pac->acl_ifindex != prev_index) {
206 dev = __dev_get_by_index(net, pac->acl_ifindex);
207 prev_index = pac->acl_ifindex;
208 }
209 if (dev)
210 ipv6_dev_ac_dec(dev, &pac->acl_addr);
211 sock_kfree_s(sk, pac, sizeof(*pac));
212 pac = next;
213 }
214 rtnl_unlock();
215 }
216
217 static void ipv6_add_acaddr_hash(struct net *net, struct ifacaddr6 *aca)
218 {
219 unsigned int hash = inet6_acaddr_hash(net, &aca->aca_addr);
220
221 spin_lock(&acaddr_hash_lock);
222 hlist_add_head_rcu(&aca->aca_addr_lst, &inet6_acaddr_lst[hash]);
223 spin_unlock(&acaddr_hash_lock);
224 }
225
226 static void ipv6_del_acaddr_hash(struct ifacaddr6 *aca)
227 {
228 spin_lock(&acaddr_hash_lock);
229 hlist_del_init_rcu(&aca->aca_addr_lst);
230 spin_unlock(&acaddr_hash_lock);
231 }
232
233 static void aca_get(struct ifacaddr6 *aca)
234 {
235 refcount_inc(&aca->aca_refcnt);
236 }
237
238 static void aca_free_rcu(struct rcu_head *h)
239 {
240 struct ifacaddr6 *aca = container_of(h, struct ifacaddr6, rcu);
241
242 fib6_info_release(aca->aca_rt);
243 kfree(aca);
244 }
245
246 static void aca_put(struct ifacaddr6 *ac)
247 {
248 if (refcount_dec_and_test(&ac->aca_refcnt)) {
249 call_rcu(&ac->rcu, aca_free_rcu);
250 }
251 }
252
253 static struct ifacaddr6 *aca_alloc(struct fib6_info *f6i,
254 const struct in6_addr *addr)
255 {
256 struct ifacaddr6 *aca;
257
258 aca = kzalloc(sizeof(*aca), GFP_ATOMIC);
259 if (!aca)
260 return NULL;
261
262 aca->aca_addr = *addr;
263 fib6_info_hold(f6i);
264 aca->aca_rt = f6i;
265 INIT_HLIST_NODE(&aca->aca_addr_lst);
266 aca->aca_users = 1;
267 /* aca_tstamp should be updated upon changes */
268 aca->aca_cstamp = aca->aca_tstamp = jiffies;
269 refcount_set(&aca->aca_refcnt, 1);
270
271 return aca;
272 }
273
274 /*
275 * device anycast group inc (add if not found)
276 */
277 int __ipv6_dev_ac_inc(struct inet6_dev *idev, const struct in6_addr *addr)
278 {
279 struct ifacaddr6 *aca;
280 struct fib6_info *f6i;
281 struct net *net;
282 int err;
283
284 ASSERT_RTNL();
285
286 write_lock_bh(&idev->lock);
287 if (idev->dead) {
288 err = -ENODEV;
289 goto out;
290 }
291
292 for (aca = idev->ac_list; aca; aca = aca->aca_next) {
293 if (ipv6_addr_equal(&aca->aca_addr, addr)) {
294 aca->aca_users++;
295 err = 0;
296 goto out;
297 }
298 }
299
300 net = dev_net(idev->dev);
301 f6i = addrconf_f6i_alloc(net, idev, addr, true, GFP_ATOMIC);
302 if (IS_ERR(f6i)) {
303 err = PTR_ERR(f6i);
304 goto out;
305 }
306 aca = aca_alloc(f6i, addr);
307 if (!aca) {
308 fib6_info_release(f6i);
309 err = -ENOMEM;
310 goto out;
311 }
312
313 aca->aca_next = idev->ac_list;
314 idev->ac_list = aca;
315
316 /* Hold this for addrconf_join_solict() below before we unlock,
317 * it is already exposed via idev->ac_list.
318 */
319 aca_get(aca);
320 write_unlock_bh(&idev->lock);
321
322 ipv6_add_acaddr_hash(net, aca);
323
324 ip6_ins_rt(net, f6i);
325
326 addrconf_join_solict(idev->dev, &aca->aca_addr);
327
328 aca_put(aca);
329 return 0;
330 out:
331 write_unlock_bh(&idev->lock);
332 return err;
333 }
334
335 /*
336 * device anycast group decrement
337 */
338 int __ipv6_dev_ac_dec(struct inet6_dev *idev, const struct in6_addr *addr)
339 {
340 struct ifacaddr6 *aca, *prev_aca;
341
342 ASSERT_RTNL();
343
344 write_lock_bh(&idev->lock);
345 prev_aca = NULL;
346 for (aca = idev->ac_list; aca; aca = aca->aca_next) {
347 if (ipv6_addr_equal(&aca->aca_addr, addr))
348 break;
349 prev_aca = aca;
350 }
351 if (!aca) {
352 write_unlock_bh(&idev->lock);
353 return -ENOENT;
354 }
355 if (--aca->aca_users > 0) {
356 write_unlock_bh(&idev->lock);
357 return 0;
358 }
359 if (prev_aca)
360 prev_aca->aca_next = aca->aca_next;
361 else
362 idev->ac_list = aca->aca_next;
363 write_unlock_bh(&idev->lock);
364 ipv6_del_acaddr_hash(aca);
365 addrconf_leave_solict(idev, &aca->aca_addr);
366
367 ip6_del_rt(dev_net(idev->dev), aca->aca_rt);
368
369 aca_put(aca);
370 return 0;
371 }
372
373 /* called with rtnl_lock() */
374 static int ipv6_dev_ac_dec(struct net_device *dev, const struct in6_addr *addr)
375 {
376 struct inet6_dev *idev = __in6_dev_get(dev);
377
378 if (!idev)
379 return -ENODEV;
380 return __ipv6_dev_ac_dec(idev, addr);
381 }
382
383 void ipv6_ac_destroy_dev(struct inet6_dev *idev)
384 {
385 struct ifacaddr6 *aca;
386
387 write_lock_bh(&idev->lock);
388 while ((aca = idev->ac_list) != NULL) {
389 idev->ac_list = aca->aca_next;
390 write_unlock_bh(&idev->lock);
391
392 ipv6_del_acaddr_hash(aca);
393
394 addrconf_leave_solict(idev, &aca->aca_addr);
395
396 ip6_del_rt(dev_net(idev->dev), aca->aca_rt);
397
398 aca_put(aca);
399
400 write_lock_bh(&idev->lock);
401 }
402 write_unlock_bh(&idev->lock);
403 }
404
405 /*
406 * check if the interface has this anycast address
407 * called with rcu_read_lock()
408 */
409 static bool ipv6_chk_acast_dev(struct net_device *dev, const struct in6_addr *addr)
410 {
411 struct inet6_dev *idev;
412 struct ifacaddr6 *aca;
413
414 idev = __in6_dev_get(dev);
415 if (idev) {
416 read_lock_bh(&idev->lock);
417 for (aca = idev->ac_list; aca; aca = aca->aca_next)
418 if (ipv6_addr_equal(&aca->aca_addr, addr))
419 break;
420 read_unlock_bh(&idev->lock);
421 return aca != NULL;
422 }
423 return false;
424 }
425
426 /*
427 * check if given interface (or any, if dev==0) has this anycast address
428 */
429 bool ipv6_chk_acast_addr(struct net *net, struct net_device *dev,
430 const struct in6_addr *addr)
431 {
432 struct net_device *nh_dev;
433 struct ifacaddr6 *aca;
434 bool found = false;
435
436 rcu_read_lock();
437 if (dev)
438 found = ipv6_chk_acast_dev(dev, addr);
439 else {
440 unsigned int hash = inet6_acaddr_hash(net, addr);
441
442 hlist_for_each_entry_rcu(aca, &inet6_acaddr_lst[hash],
443 aca_addr_lst) {
444 nh_dev = fib6_info_nh_dev(aca->aca_rt);
445 if (!nh_dev || !net_eq(dev_net(nh_dev), net))
446 continue;
447 if (ipv6_addr_equal(&aca->aca_addr, addr)) {
448 found = true;
449 break;
450 }
451 }
452 }
453 rcu_read_unlock();
454 return found;
455 }
456
457 /* check if this anycast address is link-local on given interface or
458 * is global
459 */
460 bool ipv6_chk_acast_addr_src(struct net *net, struct net_device *dev,
461 const struct in6_addr *addr)
462 {
463 return ipv6_chk_acast_addr(net,
464 (ipv6_addr_type(addr) & IPV6_ADDR_LINKLOCAL ?
465 dev : NULL),
466 addr);
467 }
468
469 #ifdef CONFIG_PROC_FS
470 struct ac6_iter_state {
471 struct seq_net_private p;
472 struct net_device *dev;
473 struct inet6_dev *idev;
474 };
475
476 #define ac6_seq_private(seq) ((struct ac6_iter_state *)(seq)->private)
477
478 static inline struct ifacaddr6 *ac6_get_first(struct seq_file *seq)
479 {
480 struct ifacaddr6 *im = NULL;
481 struct ac6_iter_state *state = ac6_seq_private(seq);
482 struct net *net = seq_file_net(seq);
483
484 state->idev = NULL;
485 for_each_netdev_rcu(net, state->dev) {
486 struct inet6_dev *idev;
487 idev = __in6_dev_get(state->dev);
488 if (!idev)
489 continue;
490 read_lock_bh(&idev->lock);
491 im = idev->ac_list;
492 if (im) {
493 state->idev = idev;
494 break;
495 }
496 read_unlock_bh(&idev->lock);
497 }
498 return im;
499 }
500
501 static struct ifacaddr6 *ac6_get_next(struct seq_file *seq, struct ifacaddr6 *im)
502 {
503 struct ac6_iter_state *state = ac6_seq_private(seq);
504
505 im = im->aca_next;
506 while (!im) {
507 if (likely(state->idev != NULL))
508 read_unlock_bh(&state->idev->lock);
509
510 state->dev = next_net_device_rcu(state->dev);
511 if (!state->dev) {
512 state->idev = NULL;
513 break;
514 }
515 state->idev = __in6_dev_get(state->dev);
516 if (!state->idev)
517 continue;
518 read_lock_bh(&state->idev->lock);
519 im = state->idev->ac_list;
520 }
521 return im;
522 }
523
524 static struct ifacaddr6 *ac6_get_idx(struct seq_file *seq, loff_t pos)
525 {
526 struct ifacaddr6 *im = ac6_get_first(seq);
527 if (im)
528 while (pos && (im = ac6_get_next(seq, im)) != NULL)
529 --pos;
530 return pos ? NULL : im;
531 }
532
533 static void *ac6_seq_start(struct seq_file *seq, loff_t *pos)
534 __acquires(RCU)
535 {
536 rcu_read_lock();
537 return ac6_get_idx(seq, *pos);
538 }
539
540 static void *ac6_seq_next(struct seq_file *seq, void *v, loff_t *pos)
541 {
542 struct ifacaddr6 *im = ac6_get_next(seq, v);
543
544 ++*pos;
545 return im;
546 }
547
548 static void ac6_seq_stop(struct seq_file *seq, void *v)
549 __releases(RCU)
550 {
551 struct ac6_iter_state *state = ac6_seq_private(seq);
552
553 if (likely(state->idev != NULL)) {
554 read_unlock_bh(&state->idev->lock);
555 state->idev = NULL;
556 }
557 rcu_read_unlock();
558 }
559
560 static int ac6_seq_show(struct seq_file *seq, void *v)
561 {
562 struct ifacaddr6 *im = (struct ifacaddr6 *)v;
563 struct ac6_iter_state *state = ac6_seq_private(seq);
564
565 seq_printf(seq, "%-4d %-15s %pi6 %5d\n",
566 state->dev->ifindex, state->dev->name,
567 &im->aca_addr, im->aca_users);
568 return 0;
569 }
570
571 static const struct seq_operations ac6_seq_ops = {
572 .start = ac6_seq_start,
573 .next = ac6_seq_next,
574 .stop = ac6_seq_stop,
575 .show = ac6_seq_show,
576 };
577
578 int __net_init ac6_proc_init(struct net *net)
579 {
580 if (!proc_create_net("anycast6", 0444, net->proc_net, &ac6_seq_ops,
581 sizeof(struct ac6_iter_state)))
582 return -ENOMEM;
583
584 return 0;
585 }
586
587 void ac6_proc_exit(struct net *net)
588 {
589 remove_proc_entry("anycast6", net->proc_net);
590 }
591 #endif
592
593 /* Init / cleanup code
594 */
595 int __init ipv6_anycast_init(void)
596 {
597 int i;
598
599 for (i = 0; i < IN6_ADDR_HSIZE; i++)
600 INIT_HLIST_HEAD(&inet6_acaddr_lst[i]);
601 return 0;
602 }
603
604 void ipv6_anycast_cleanup(void)
605 {
606 int i;
607
608 spin_lock(&acaddr_hash_lock);
609 for (i = 0; i < IN6_ADDR_HSIZE; i++)
610 WARN_ON(!hlist_empty(&inet6_acaddr_lst[i]));
611 spin_unlock(&acaddr_hash_lock);
612 }
613
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