xref: /openbmc/linux/net/ipv6/anycast.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
1 /*
2  *	Anycast support for IPv6
3  *	Linux INET6 implementation
4  *
5  *	Authors:
6  *	David L Stevens (dlstevens@us.ibm.com)
7  *
8  *	based heavily on net/ipv6/mcast.c
9  *
10  *	This program is free software; you can redistribute it and/or
11  *      modify it under the terms of the GNU General Public License
12  *      as published by the Free Software Foundation; either version
13  *      2 of the License, or (at your option) any later version.
14  */
15 
16 #include <linux/capability.h>
17 #include <linux/module.h>
18 #include <linux/errno.h>
19 #include <linux/types.h>
20 #include <linux/random.h>
21 #include <linux/string.h>
22 #include <linux/socket.h>
23 #include <linux/sockios.h>
24 #include <linux/net.h>
25 #include <linux/in6.h>
26 #include <linux/netdevice.h>
27 #include <linux/if_arp.h>
28 #include <linux/route.h>
29 #include <linux/init.h>
30 #include <linux/proc_fs.h>
31 #include <linux/seq_file.h>
32 
33 #include <net/sock.h>
34 #include <net/snmp.h>
35 
36 #include <net/ipv6.h>
37 #include <net/protocol.h>
38 #include <net/if_inet6.h>
39 #include <net/ndisc.h>
40 #include <net/addrconf.h>
41 #include <net/ip6_route.h>
42 
43 #include <net/checksum.h>
44 
45 static int ipv6_dev_ac_dec(struct net_device *dev, struct in6_addr *addr);
46 
47 /* Big ac list lock for all the sockets */
48 static DEFINE_RWLOCK(ipv6_sk_ac_lock);
49 
50 static int
51 ip6_onlink(struct in6_addr *addr, struct net_device *dev)
52 {
53 	struct inet6_dev	*idev;
54 	struct inet6_ifaddr	*ifa;
55 	int	onlink;
56 
57 	onlink = 0;
58 	rcu_read_lock();
59 	idev = __in6_dev_get(dev);
60 	if (idev) {
61 		read_lock_bh(&idev->lock);
62 		for (ifa=idev->addr_list; ifa; ifa=ifa->if_next) {
63 			onlink = ipv6_prefix_equal(addr, &ifa->addr,
64 						   ifa->prefix_len);
65 			if (onlink)
66 				break;
67 		}
68 		read_unlock_bh(&idev->lock);
69 	}
70 	rcu_read_unlock();
71 	return onlink;
72 }
73 
74 /*
75  *	socket join an anycast group
76  */
77 
78 int ipv6_sock_ac_join(struct sock *sk, int ifindex, struct in6_addr *addr)
79 {
80 	struct ipv6_pinfo *np = inet6_sk(sk);
81 	struct net_device *dev = NULL;
82 	struct inet6_dev *idev;
83 	struct ipv6_ac_socklist *pac;
84 	int	ishost = !ipv6_devconf.forwarding;
85 	int	err = 0;
86 
87 	if (!capable(CAP_NET_ADMIN))
88 		return -EPERM;
89 	if (ipv6_addr_is_multicast(addr))
90 		return -EINVAL;
91 	if (ipv6_chk_addr(addr, NULL, 0))
92 		return -EINVAL;
93 
94 	pac = sock_kmalloc(sk, sizeof(struct ipv6_ac_socklist), GFP_KERNEL);
95 	if (pac == NULL)
96 		return -ENOMEM;
97 	pac->acl_next = NULL;
98 	ipv6_addr_copy(&pac->acl_addr, addr);
99 
100 	if (ifindex == 0) {
101 		struct rt6_info *rt;
102 
103 		rt = rt6_lookup(addr, NULL, 0, 0);
104 		if (rt) {
105 			dev = rt->rt6i_dev;
106 			dev_hold(dev);
107 			dst_release(&rt->u.dst);
108 		} else if (ishost) {
109 			err = -EADDRNOTAVAIL;
110 			goto out_free_pac;
111 		} else {
112 			/* router, no matching interface: just pick one */
113 
114 			dev = dev_get_by_flags(IFF_UP, IFF_UP|IFF_LOOPBACK);
115 		}
116 	} else
117 		dev = dev_get_by_index(ifindex);
118 
119 	if (dev == NULL) {
120 		err = -ENODEV;
121 		goto out_free_pac;
122 	}
123 
124 	idev = in6_dev_get(dev);
125 	if (!idev) {
126 		if (ifindex)
127 			err = -ENODEV;
128 		else
129 			err = -EADDRNOTAVAIL;
130 		goto out_dev_put;
131 	}
132 	/* reset ishost, now that we have a specific device */
133 	ishost = !idev->cnf.forwarding;
134 	in6_dev_put(idev);
135 
136 	pac->acl_ifindex = dev->ifindex;
137 
138 	/* XXX
139 	 * For hosts, allow link-local or matching prefix anycasts.
140 	 * This obviates the need for propagating anycast routes while
141 	 * still allowing some non-router anycast participation.
142 	 */
143 	if (!ip6_onlink(addr, dev)) {
144 		if (ishost)
145 			err = -EADDRNOTAVAIL;
146 		if (err)
147 			goto out_dev_put;
148 	}
149 
150 	err = ipv6_dev_ac_inc(dev, addr);
151 	if (err)
152 		goto out_dev_put;
153 
154 	write_lock_bh(&ipv6_sk_ac_lock);
155 	pac->acl_next = np->ipv6_ac_list;
156 	np->ipv6_ac_list = pac;
157 	write_unlock_bh(&ipv6_sk_ac_lock);
158 
159 	dev_put(dev);
160 
161 	return 0;
162 
163 out_dev_put:
164 	dev_put(dev);
165 out_free_pac:
166 	sock_kfree_s(sk, pac, sizeof(*pac));
167 	return err;
168 }
169 
170 /*
171  *	socket leave an anycast group
172  */
173 int ipv6_sock_ac_drop(struct sock *sk, int ifindex, struct in6_addr *addr)
174 {
175 	struct ipv6_pinfo *np = inet6_sk(sk);
176 	struct net_device *dev;
177 	struct ipv6_ac_socklist *pac, *prev_pac;
178 
179 	write_lock_bh(&ipv6_sk_ac_lock);
180 	prev_pac = NULL;
181 	for (pac = np->ipv6_ac_list; pac; pac = pac->acl_next) {
182 		if ((ifindex == 0 || pac->acl_ifindex == ifindex) &&
183 		     ipv6_addr_equal(&pac->acl_addr, addr))
184 			break;
185 		prev_pac = pac;
186 	}
187 	if (!pac) {
188 		write_unlock_bh(&ipv6_sk_ac_lock);
189 		return -ENOENT;
190 	}
191 	if (prev_pac)
192 		prev_pac->acl_next = pac->acl_next;
193 	else
194 		np->ipv6_ac_list = pac->acl_next;
195 
196 	write_unlock_bh(&ipv6_sk_ac_lock);
197 
198 	dev = dev_get_by_index(pac->acl_ifindex);
199 	if (dev) {
200 		ipv6_dev_ac_dec(dev, &pac->acl_addr);
201 		dev_put(dev);
202 	}
203 	sock_kfree_s(sk, pac, sizeof(*pac));
204 	return 0;
205 }
206 
207 void ipv6_sock_ac_close(struct sock *sk)
208 {
209 	struct ipv6_pinfo *np = inet6_sk(sk);
210 	struct net_device *dev = NULL;
211 	struct ipv6_ac_socklist *pac;
212 	int	prev_index;
213 
214 	write_lock_bh(&ipv6_sk_ac_lock);
215 	pac = np->ipv6_ac_list;
216 	np->ipv6_ac_list = NULL;
217 	write_unlock_bh(&ipv6_sk_ac_lock);
218 
219 	prev_index = 0;
220 	while (pac) {
221 		struct ipv6_ac_socklist *next = pac->acl_next;
222 
223 		if (pac->acl_ifindex != prev_index) {
224 			if (dev)
225 				dev_put(dev);
226 			dev = dev_get_by_index(pac->acl_ifindex);
227 			prev_index = pac->acl_ifindex;
228 		}
229 		if (dev)
230 			ipv6_dev_ac_dec(dev, &pac->acl_addr);
231 		sock_kfree_s(sk, pac, sizeof(*pac));
232 		pac = next;
233 	}
234 	if (dev)
235 		dev_put(dev);
236 }
237 
238 #if 0
239 /* The function is not used, which is funny. Apparently, author
240  * supposed to use it to filter out datagrams inside udp/raw but forgot.
241  *
242  * It is OK, anycasts are not special comparing to delivery to unicasts.
243  */
244 
245 int inet6_ac_check(struct sock *sk, struct in6_addr *addr, int ifindex)
246 {
247 	struct ipv6_ac_socklist *pac;
248 	struct ipv6_pinfo *np = inet6_sk(sk);
249 	int	found;
250 
251 	found = 0;
252 	read_lock(&ipv6_sk_ac_lock);
253 	for (pac=np->ipv6_ac_list; pac; pac=pac->acl_next) {
254 		if (ifindex && pac->acl_ifindex != ifindex)
255 			continue;
256 		found = ipv6_addr_equal(&pac->acl_addr, addr);
257 		if (found)
258 			break;
259 	}
260 	read_unlock(&ipv6_sk_ac_lock);
261 
262 	return found;
263 }
264 
265 #endif
266 
267 static void aca_put(struct ifacaddr6 *ac)
268 {
269 	if (atomic_dec_and_test(&ac->aca_refcnt)) {
270 		in6_dev_put(ac->aca_idev);
271 		dst_release(&ac->aca_rt->u.dst);
272 		kfree(ac);
273 	}
274 }
275 
276 /*
277  *	device anycast group inc (add if not found)
278  */
279 int ipv6_dev_ac_inc(struct net_device *dev, struct in6_addr *addr)
280 {
281 	struct ifacaddr6 *aca;
282 	struct inet6_dev *idev;
283 	struct rt6_info *rt;
284 	int err;
285 
286 	idev = in6_dev_get(dev);
287 
288 	if (idev == NULL)
289 		return -EINVAL;
290 
291 	write_lock_bh(&idev->lock);
292 	if (idev->dead) {
293 		err = -ENODEV;
294 		goto out;
295 	}
296 
297 	for (aca = idev->ac_list; aca; aca = aca->aca_next) {
298 		if (ipv6_addr_equal(&aca->aca_addr, addr)) {
299 			aca->aca_users++;
300 			err = 0;
301 			goto out;
302 		}
303 	}
304 
305 	/*
306 	 *	not found: create a new one.
307 	 */
308 
309 	aca = kzalloc(sizeof(struct ifacaddr6), GFP_ATOMIC);
310 
311 	if (aca == NULL) {
312 		err = -ENOMEM;
313 		goto out;
314 	}
315 
316 	rt = addrconf_dst_alloc(idev, addr, 1);
317 	if (IS_ERR(rt)) {
318 		kfree(aca);
319 		err = PTR_ERR(rt);
320 		goto out;
321 	}
322 
323 	ipv6_addr_copy(&aca->aca_addr, addr);
324 	aca->aca_idev = idev;
325 	aca->aca_rt = rt;
326 	aca->aca_users = 1;
327 	/* aca_tstamp should be updated upon changes */
328 	aca->aca_cstamp = aca->aca_tstamp = jiffies;
329 	atomic_set(&aca->aca_refcnt, 2);
330 	spin_lock_init(&aca->aca_lock);
331 
332 	aca->aca_next = idev->ac_list;
333 	idev->ac_list = aca;
334 	write_unlock_bh(&idev->lock);
335 
336 	dst_hold(&rt->u.dst);
337 	if (ip6_ins_rt(rt))
338 		dst_release(&rt->u.dst);
339 
340 	addrconf_join_solict(dev, &aca->aca_addr);
341 
342 	aca_put(aca);
343 	return 0;
344 out:
345 	write_unlock_bh(&idev->lock);
346 	in6_dev_put(idev);
347 	return err;
348 }
349 
350 /*
351  *	device anycast group decrement
352  */
353 int __ipv6_dev_ac_dec(struct inet6_dev *idev, struct in6_addr *addr)
354 {
355 	struct ifacaddr6 *aca, *prev_aca;
356 
357 	write_lock_bh(&idev->lock);
358 	prev_aca = NULL;
359 	for (aca = idev->ac_list; aca; aca = aca->aca_next) {
360 		if (ipv6_addr_equal(&aca->aca_addr, addr))
361 			break;
362 		prev_aca = aca;
363 	}
364 	if (!aca) {
365 		write_unlock_bh(&idev->lock);
366 		return -ENOENT;
367 	}
368 	if (--aca->aca_users > 0) {
369 		write_unlock_bh(&idev->lock);
370 		return 0;
371 	}
372 	if (prev_aca)
373 		prev_aca->aca_next = aca->aca_next;
374 	else
375 		idev->ac_list = aca->aca_next;
376 	write_unlock_bh(&idev->lock);
377 	addrconf_leave_solict(idev, &aca->aca_addr);
378 
379 	dst_hold(&aca->aca_rt->u.dst);
380 	if (ip6_del_rt(aca->aca_rt))
381 		dst_free(&aca->aca_rt->u.dst);
382 	else
383 		dst_release(&aca->aca_rt->u.dst);
384 
385 	aca_put(aca);
386 	return 0;
387 }
388 
389 static int ipv6_dev_ac_dec(struct net_device *dev, struct in6_addr *addr)
390 {
391 	int ret;
392 	struct inet6_dev *idev = in6_dev_get(dev);
393 	if (idev == NULL)
394 		return -ENODEV;
395 	ret = __ipv6_dev_ac_dec(idev, addr);
396 	in6_dev_put(idev);
397 	return ret;
398 }
399 
400 /*
401  *	check if the interface has this anycast address
402  */
403 static int ipv6_chk_acast_dev(struct net_device *dev, struct in6_addr *addr)
404 {
405 	struct inet6_dev *idev;
406 	struct ifacaddr6 *aca;
407 
408 	idev = in6_dev_get(dev);
409 	if (idev) {
410 		read_lock_bh(&idev->lock);
411 		for (aca = idev->ac_list; aca; aca = aca->aca_next)
412 			if (ipv6_addr_equal(&aca->aca_addr, addr))
413 				break;
414 		read_unlock_bh(&idev->lock);
415 		in6_dev_put(idev);
416 		return aca != 0;
417 	}
418 	return 0;
419 }
420 
421 /*
422  *	check if given interface (or any, if dev==0) has this anycast address
423  */
424 int ipv6_chk_acast_addr(struct net_device *dev, struct in6_addr *addr)
425 {
426 	int found = 0;
427 
428 	if (dev)
429 		return ipv6_chk_acast_dev(dev, addr);
430 	read_lock(&dev_base_lock);
431 	for_each_netdev(dev)
432 		if (ipv6_chk_acast_dev(dev, addr)) {
433 			found = 1;
434 			break;
435 		}
436 	read_unlock(&dev_base_lock);
437 	return found;
438 }
439 
440 
441 #ifdef CONFIG_PROC_FS
442 struct ac6_iter_state {
443 	struct net_device *dev;
444 	struct inet6_dev *idev;
445 };
446 
447 #define ac6_seq_private(seq)	((struct ac6_iter_state *)(seq)->private)
448 
449 static inline struct ifacaddr6 *ac6_get_first(struct seq_file *seq)
450 {
451 	struct ifacaddr6 *im = NULL;
452 	struct ac6_iter_state *state = ac6_seq_private(seq);
453 
454 	state->idev = NULL;
455 	for_each_netdev(state->dev) {
456 		struct inet6_dev *idev;
457 		idev = in6_dev_get(state->dev);
458 		if (!idev)
459 			continue;
460 		read_lock_bh(&idev->lock);
461 		im = idev->ac_list;
462 		if (im) {
463 			state->idev = idev;
464 			break;
465 		}
466 		read_unlock_bh(&idev->lock);
467 		in6_dev_put(idev);
468 	}
469 	return im;
470 }
471 
472 static struct ifacaddr6 *ac6_get_next(struct seq_file *seq, struct ifacaddr6 *im)
473 {
474 	struct ac6_iter_state *state = ac6_seq_private(seq);
475 
476 	im = im->aca_next;
477 	while (!im) {
478 		if (likely(state->idev != NULL)) {
479 			read_unlock_bh(&state->idev->lock);
480 			in6_dev_put(state->idev);
481 		}
482 		state->dev = next_net_device(state->dev);
483 		if (!state->dev) {
484 			state->idev = NULL;
485 			break;
486 		}
487 		state->idev = in6_dev_get(state->dev);
488 		if (!state->idev)
489 			continue;
490 		read_lock_bh(&state->idev->lock);
491 		im = state->idev->ac_list;
492 	}
493 	return im;
494 }
495 
496 static struct ifacaddr6 *ac6_get_idx(struct seq_file *seq, loff_t pos)
497 {
498 	struct ifacaddr6 *im = ac6_get_first(seq);
499 	if (im)
500 		while (pos && (im = ac6_get_next(seq, im)) != NULL)
501 			--pos;
502 	return pos ? NULL : im;
503 }
504 
505 static void *ac6_seq_start(struct seq_file *seq, loff_t *pos)
506 {
507 	read_lock(&dev_base_lock);
508 	return ac6_get_idx(seq, *pos);
509 }
510 
511 static void *ac6_seq_next(struct seq_file *seq, void *v, loff_t *pos)
512 {
513 	struct ifacaddr6 *im;
514 	im = ac6_get_next(seq, v);
515 	++*pos;
516 	return im;
517 }
518 
519 static void ac6_seq_stop(struct seq_file *seq, void *v)
520 {
521 	struct ac6_iter_state *state = ac6_seq_private(seq);
522 	if (likely(state->idev != NULL)) {
523 		read_unlock_bh(&state->idev->lock);
524 		in6_dev_put(state->idev);
525 	}
526 	read_unlock(&dev_base_lock);
527 }
528 
529 static int ac6_seq_show(struct seq_file *seq, void *v)
530 {
531 	struct ifacaddr6 *im = (struct ifacaddr6 *)v;
532 	struct ac6_iter_state *state = ac6_seq_private(seq);
533 
534 	seq_printf(seq,
535 		   "%-4d %-15s " NIP6_SEQFMT " %5d\n",
536 		   state->dev->ifindex, state->dev->name,
537 		   NIP6(im->aca_addr),
538 		   im->aca_users);
539 	return 0;
540 }
541 
542 static struct seq_operations ac6_seq_ops = {
543 	.start	=	ac6_seq_start,
544 	.next	=	ac6_seq_next,
545 	.stop	=	ac6_seq_stop,
546 	.show	=	ac6_seq_show,
547 };
548 
549 static int ac6_seq_open(struct inode *inode, struct file *file)
550 {
551 	struct seq_file *seq;
552 	int rc = -ENOMEM;
553 	struct ac6_iter_state *s = kzalloc(sizeof(*s), GFP_KERNEL);
554 
555 	if (!s)
556 		goto out;
557 
558 	rc = seq_open(file, &ac6_seq_ops);
559 	if (rc)
560 		goto out_kfree;
561 
562 	seq = file->private_data;
563 	seq->private = s;
564 out:
565 	return rc;
566 out_kfree:
567 	kfree(s);
568 	goto out;
569 }
570 
571 static const struct file_operations ac6_seq_fops = {
572 	.owner		=	THIS_MODULE,
573 	.open		=	ac6_seq_open,
574 	.read		=	seq_read,
575 	.llseek		=	seq_lseek,
576 	.release	=	seq_release_private,
577 };
578 
579 int __init ac6_proc_init(void)
580 {
581 	if (!proc_net_fops_create("anycast6", S_IRUGO, &ac6_seq_fops))
582 		return -ENOMEM;
583 
584 	return 0;
585 }
586 
587 void ac6_proc_exit(void)
588 {
589 	proc_net_remove("anycast6");
590 }
591 #endif
592 
593