xref: /openbmc/linux/net/ipv6/anycast.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
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/config.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/sched.h>
25 #include <linux/net.h>
26 #include <linux/in6.h>
27 #include <linux/netdevice.h>
28 #include <linux/if_arp.h>
29 #include <linux/route.h>
30 #include <linux/init.h>
31 #include <linux/proc_fs.h>
32 #include <linux/seq_file.h>
33 
34 #include <net/sock.h>
35 #include <net/snmp.h>
36 
37 #include <net/ipv6.h>
38 #include <net/protocol.h>
39 #include <net/if_inet6.h>
40 #include <net/ndisc.h>
41 #include <net/addrconf.h>
42 #include <net/ip6_route.h>
43 
44 #include <net/checksum.h>
45 
46 static int ipv6_dev_ac_dec(struct net_device *dev, struct in6_addr *addr);
47 
48 /* Big ac list lock for all the sockets */
49 static DEFINE_RWLOCK(ipv6_sk_ac_lock);
50 
51 static int
52 ip6_onlink(struct in6_addr *addr, struct net_device *dev)
53 {
54 	struct inet6_dev	*idev;
55 	struct inet6_ifaddr	*ifa;
56 	int	onlink;
57 
58 	onlink = 0;
59 	read_lock(&addrconf_lock);
60 	idev = __in6_dev_get(dev);
61 	if (idev) {
62 		read_lock_bh(&idev->lock);
63 		for (ifa=idev->addr_list; ifa; ifa=ifa->if_next) {
64 			onlink = ipv6_prefix_equal(addr, &ifa->addr,
65 						   ifa->prefix_len);
66 			if (onlink)
67 				break;
68 		}
69 		read_unlock_bh(&idev->lock);
70 	}
71 	read_unlock(&addrconf_lock);
72 	return onlink;
73 }
74 
75 /*
76  *	socket join an anycast group
77  */
78 
79 int ipv6_sock_ac_join(struct sock *sk, int ifindex, struct in6_addr *addr)
80 {
81 	struct ipv6_pinfo *np = inet6_sk(sk);
82 	struct net_device *dev = NULL;
83 	struct inet6_dev *idev;
84 	struct ipv6_ac_socklist *pac;
85 	int	ishost = !ipv6_devconf.forwarding;
86 	int	err = 0;
87 
88 	if (!capable(CAP_NET_ADMIN))
89 		return -EPERM;
90 	if (ipv6_addr_is_multicast(addr))
91 		return -EINVAL;
92 	if (ipv6_chk_addr(addr, NULL, 0))
93 		return -EINVAL;
94 
95 	pac = sock_kmalloc(sk, sizeof(struct ipv6_ac_socklist), GFP_KERNEL);
96 	if (pac == NULL)
97 		return -ENOMEM;
98 	pac->acl_next = NULL;
99 	ipv6_addr_copy(&pac->acl_addr, addr);
100 
101 	if (ifindex == 0) {
102 		struct rt6_info *rt;
103 
104 		rt = rt6_lookup(addr, NULL, 0, 0);
105 		if (rt) {
106 			dev = rt->rt6i_dev;
107 			dev_hold(dev);
108 			dst_release(&rt->u.dst);
109 		} else if (ishost) {
110 			err = -EADDRNOTAVAIL;
111 			goto out_free_pac;
112 		} else {
113 			/* router, no matching interface: just pick one */
114 
115 			dev = dev_get_by_flags(IFF_UP, IFF_UP|IFF_LOOPBACK);
116 		}
117 	} else
118 		dev = dev_get_by_index(ifindex);
119 
120 	if (dev == NULL) {
121 		err = -ENODEV;
122 		goto out_free_pac;
123 	}
124 
125 	idev = in6_dev_get(dev);
126 	if (!idev) {
127 		if (ifindex)
128 			err = -ENODEV;
129 		else
130 			err = -EADDRNOTAVAIL;
131 		goto out_dev_put;
132 	}
133 	/* reset ishost, now that we have a specific device */
134 	ishost = !idev->cnf.forwarding;
135 	in6_dev_put(idev);
136 
137 	pac->acl_ifindex = dev->ifindex;
138 
139 	/* XXX
140 	 * For hosts, allow link-local or matching prefix anycasts.
141 	 * This obviates the need for propagating anycast routes while
142 	 * still allowing some non-router anycast participation.
143 	 */
144 	if (!ip6_onlink(addr, dev)) {
145 		if (ishost)
146 			err = -EADDRNOTAVAIL;
147 		if (err)
148 			goto out_dev_put;
149 	}
150 
151 	err = ipv6_dev_ac_inc(dev, addr);
152 	if (err)
153 		goto out_dev_put;
154 
155 	write_lock_bh(&ipv6_sk_ac_lock);
156 	pac->acl_next = np->ipv6_ac_list;
157 	np->ipv6_ac_list = pac;
158 	write_unlock_bh(&ipv6_sk_ac_lock);
159 
160 	dev_put(dev);
161 
162 	return 0;
163 
164 out_dev_put:
165 	dev_put(dev);
166 out_free_pac:
167 	sock_kfree_s(sk, pac, sizeof(*pac));
168 	return err;
169 }
170 
171 /*
172  *	socket leave an anycast group
173  */
174 int ipv6_sock_ac_drop(struct sock *sk, int ifindex, struct in6_addr *addr)
175 {
176 	struct ipv6_pinfo *np = inet6_sk(sk);
177 	struct net_device *dev;
178 	struct ipv6_ac_socklist *pac, *prev_pac;
179 
180 	write_lock_bh(&ipv6_sk_ac_lock);
181 	prev_pac = NULL;
182 	for (pac = np->ipv6_ac_list; pac; pac = pac->acl_next) {
183 		if ((ifindex == 0 || pac->acl_ifindex == ifindex) &&
184 		     ipv6_addr_equal(&pac->acl_addr, addr))
185 			break;
186 		prev_pac = pac;
187 	}
188 	if (!pac) {
189 		write_unlock_bh(&ipv6_sk_ac_lock);
190 		return -ENOENT;
191 	}
192 	if (prev_pac)
193 		prev_pac->acl_next = pac->acl_next;
194 	else
195 		np->ipv6_ac_list = pac->acl_next;
196 
197 	write_unlock_bh(&ipv6_sk_ac_lock);
198 
199 	dev = dev_get_by_index(pac->acl_ifindex);
200 	if (dev) {
201 		ipv6_dev_ac_dec(dev, &pac->acl_addr);
202 		dev_put(dev);
203 	}
204 	sock_kfree_s(sk, pac, sizeof(*pac));
205 	return 0;
206 }
207 
208 void ipv6_sock_ac_close(struct sock *sk)
209 {
210 	struct ipv6_pinfo *np = inet6_sk(sk);
211 	struct net_device *dev = NULL;
212 	struct ipv6_ac_socklist *pac;
213 	int	prev_index;
214 
215 	write_lock_bh(&ipv6_sk_ac_lock);
216 	pac = np->ipv6_ac_list;
217 	np->ipv6_ac_list = NULL;
218 	write_unlock_bh(&ipv6_sk_ac_lock);
219 
220 	prev_index = 0;
221 	while (pac) {
222 		struct ipv6_ac_socklist *next = pac->acl_next;
223 
224 		if (pac->acl_ifindex != prev_index) {
225 			if (dev)
226 				dev_put(dev);
227 			dev = dev_get_by_index(pac->acl_ifindex);
228 			prev_index = pac->acl_ifindex;
229 		}
230 		if (dev)
231 			ipv6_dev_ac_dec(dev, &pac->acl_addr);
232 		sock_kfree_s(sk, pac, sizeof(*pac));
233 		pac = next;
234 	}
235 	if (dev)
236 		dev_put(dev);
237 }
238 
239 #if 0
240 /* The function is not used, which is funny. Apparently, author
241  * supposed to use it to filter out datagrams inside udp/raw but forgot.
242  *
243  * It is OK, anycasts are not special comparing to delivery to unicasts.
244  */
245 
246 int inet6_ac_check(struct sock *sk, struct in6_addr *addr, int ifindex)
247 {
248 	struct ipv6_ac_socklist *pac;
249 	struct ipv6_pinfo *np = inet6_sk(sk);
250 	int	found;
251 
252 	found = 0;
253 	read_lock(&ipv6_sk_ac_lock);
254 	for (pac=np->ipv6_ac_list; pac; pac=pac->acl_next) {
255 		if (ifindex && pac->acl_ifindex != ifindex)
256 			continue;
257 		found = ipv6_addr_equal(&pac->acl_addr, addr);
258 		if (found)
259 			break;
260 	}
261 	read_unlock(&ipv6_sk_ac_lock);
262 
263 	return found;
264 }
265 
266 #endif
267 
268 static void aca_put(struct ifacaddr6 *ac)
269 {
270 	if (atomic_dec_and_test(&ac->aca_refcnt)) {
271 		in6_dev_put(ac->aca_idev);
272 		dst_release(&ac->aca_rt->u.dst);
273 		kfree(ac);
274 	}
275 }
276 
277 /*
278  *	device anycast group inc (add if not found)
279  */
280 int ipv6_dev_ac_inc(struct net_device *dev, struct in6_addr *addr)
281 {
282 	struct ifacaddr6 *aca;
283 	struct inet6_dev *idev;
284 	struct rt6_info *rt;
285 	int err;
286 
287 	idev = in6_dev_get(dev);
288 
289 	if (idev == NULL)
290 		return -EINVAL;
291 
292 	write_lock_bh(&idev->lock);
293 	if (idev->dead) {
294 		err = -ENODEV;
295 		goto out;
296 	}
297 
298 	for (aca = idev->ac_list; aca; aca = aca->aca_next) {
299 		if (ipv6_addr_equal(&aca->aca_addr, addr)) {
300 			aca->aca_users++;
301 			err = 0;
302 			goto out;
303 		}
304 	}
305 
306 	/*
307 	 *	not found: create a new one.
308 	 */
309 
310 	aca = kmalloc(sizeof(struct ifacaddr6), GFP_ATOMIC);
311 
312 	if (aca == NULL) {
313 		err = -ENOMEM;
314 		goto out;
315 	}
316 
317 	rt = addrconf_dst_alloc(idev, addr, 1);
318 	if (IS_ERR(rt)) {
319 		kfree(aca);
320 		err = PTR_ERR(rt);
321 		goto out;
322 	}
323 
324 	memset(aca, 0, sizeof(struct ifacaddr6));
325 
326 	ipv6_addr_copy(&aca->aca_addr, addr);
327 	aca->aca_idev = idev;
328 	aca->aca_rt = rt;
329 	aca->aca_users = 1;
330 	/* aca_tstamp should be updated upon changes */
331 	aca->aca_cstamp = aca->aca_tstamp = jiffies;
332 	atomic_set(&aca->aca_refcnt, 2);
333 	spin_lock_init(&aca->aca_lock);
334 
335 	aca->aca_next = idev->ac_list;
336 	idev->ac_list = aca;
337 	write_unlock_bh(&idev->lock);
338 
339 	dst_hold(&rt->u.dst);
340 	if (ip6_ins_rt(rt, NULL, NULL, NULL))
341 		dst_release(&rt->u.dst);
342 
343 	addrconf_join_solict(dev, &aca->aca_addr);
344 
345 	aca_put(aca);
346 	return 0;
347 out:
348 	write_unlock_bh(&idev->lock);
349 	in6_dev_put(idev);
350 	return err;
351 }
352 
353 /*
354  *	device anycast group decrement
355  */
356 int __ipv6_dev_ac_dec(struct inet6_dev *idev, struct in6_addr *addr)
357 {
358 	struct ifacaddr6 *aca, *prev_aca;
359 
360 	write_lock_bh(&idev->lock);
361 	prev_aca = NULL;
362 	for (aca = idev->ac_list; aca; aca = aca->aca_next) {
363 		if (ipv6_addr_equal(&aca->aca_addr, addr))
364 			break;
365 		prev_aca = aca;
366 	}
367 	if (!aca) {
368 		write_unlock_bh(&idev->lock);
369 		return -ENOENT;
370 	}
371 	if (--aca->aca_users > 0) {
372 		write_unlock_bh(&idev->lock);
373 		return 0;
374 	}
375 	if (prev_aca)
376 		prev_aca->aca_next = aca->aca_next;
377 	else
378 		idev->ac_list = aca->aca_next;
379 	write_unlock_bh(&idev->lock);
380 	addrconf_leave_solict(idev, &aca->aca_addr);
381 
382 	dst_hold(&aca->aca_rt->u.dst);
383 	if (ip6_del_rt(aca->aca_rt, NULL, NULL, NULL))
384 		dst_free(&aca->aca_rt->u.dst);
385 	else
386 		dst_release(&aca->aca_rt->u.dst);
387 
388 	aca_put(aca);
389 	return 0;
390 }
391 
392 static int ipv6_dev_ac_dec(struct net_device *dev, struct in6_addr *addr)
393 {
394 	int ret;
395 	struct inet6_dev *idev = in6_dev_get(dev);
396 	if (idev == NULL)
397 		return -ENODEV;
398 	ret = __ipv6_dev_ac_dec(idev, addr);
399 	in6_dev_put(idev);
400 	return ret;
401 }
402 
403 /*
404  *	check if the interface has this anycast address
405  */
406 static int ipv6_chk_acast_dev(struct net_device *dev, struct in6_addr *addr)
407 {
408 	struct inet6_dev *idev;
409 	struct ifacaddr6 *aca;
410 
411 	idev = in6_dev_get(dev);
412 	if (idev) {
413 		read_lock_bh(&idev->lock);
414 		for (aca = idev->ac_list; aca; aca = aca->aca_next)
415 			if (ipv6_addr_equal(&aca->aca_addr, addr))
416 				break;
417 		read_unlock_bh(&idev->lock);
418 		in6_dev_put(idev);
419 		return aca != 0;
420 	}
421 	return 0;
422 }
423 
424 /*
425  *	check if given interface (or any, if dev==0) has this anycast address
426  */
427 int ipv6_chk_acast_addr(struct net_device *dev, struct in6_addr *addr)
428 {
429 	if (dev)
430 		return ipv6_chk_acast_dev(dev, addr);
431 	read_lock(&dev_base_lock);
432 	for (dev=dev_base; dev; dev=dev->next)
433 		if (ipv6_chk_acast_dev(dev, addr))
434 			break;
435 	read_unlock(&dev_base_lock);
436 	return dev != 0;
437 }
438 
439 
440 #ifdef CONFIG_PROC_FS
441 struct ac6_iter_state {
442 	struct net_device *dev;
443 	struct inet6_dev *idev;
444 };
445 
446 #define ac6_seq_private(seq)	((struct ac6_iter_state *)(seq)->private)
447 
448 static inline struct ifacaddr6 *ac6_get_first(struct seq_file *seq)
449 {
450 	struct ifacaddr6 *im = NULL;
451 	struct ac6_iter_state *state = ac6_seq_private(seq);
452 
453 	for (state->dev = dev_base, state->idev = NULL;
454 	     state->dev;
455 	     state->dev = state->dev->next) {
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 	}
468 	return im;
469 }
470 
471 static struct ifacaddr6 *ac6_get_next(struct seq_file *seq, struct ifacaddr6 *im)
472 {
473 	struct ac6_iter_state *state = ac6_seq_private(seq);
474 
475 	im = im->aca_next;
476 	while (!im) {
477 		if (likely(state->idev != NULL)) {
478 			read_unlock_bh(&state->idev->lock);
479 			in6_dev_put(state->idev);
480 		}
481 		state->dev = state->dev->next;
482 		if (!state->dev) {
483 			state->idev = NULL;
484 			break;
485 		}
486 		state->idev = in6_dev_get(state->dev);
487 		if (!state->idev)
488 			continue;
489 		read_lock_bh(&state->idev->lock);
490 		im = state->idev->ac_list;
491 	}
492 	return im;
493 }
494 
495 static struct ifacaddr6 *ac6_get_idx(struct seq_file *seq, loff_t pos)
496 {
497 	struct ifacaddr6 *im = ac6_get_first(seq);
498 	if (im)
499 		while (pos && (im = ac6_get_next(seq, im)) != NULL)
500 			--pos;
501 	return pos ? NULL : im;
502 }
503 
504 static void *ac6_seq_start(struct seq_file *seq, loff_t *pos)
505 {
506 	read_lock(&dev_base_lock);
507 	return ac6_get_idx(seq, *pos);
508 }
509 
510 static void *ac6_seq_next(struct seq_file *seq, void *v, loff_t *pos)
511 {
512 	struct ifacaddr6 *im;
513 	im = ac6_get_next(seq, v);
514 	++*pos;
515 	return im;
516 }
517 
518 static void ac6_seq_stop(struct seq_file *seq, void *v)
519 {
520 	struct ac6_iter_state *state = ac6_seq_private(seq);
521 	if (likely(state->idev != NULL)) {
522 		read_unlock_bh(&state->idev->lock);
523 		in6_dev_put(state->idev);
524 	}
525 	read_unlock(&dev_base_lock);
526 }
527 
528 static int ac6_seq_show(struct seq_file *seq, void *v)
529 {
530 	struct ifacaddr6 *im = (struct ifacaddr6 *)v;
531 	struct ac6_iter_state *state = ac6_seq_private(seq);
532 
533 	seq_printf(seq,
534 		   "%-4d %-15s "
535 		   "%04x%04x%04x%04x%04x%04x%04x%04x "
536 		   "%5d\n",
537 		   state->dev->ifindex, state->dev->name,
538 		   NIP6(im->aca_addr),
539 		   im->aca_users);
540 	return 0;
541 }
542 
543 static struct seq_operations ac6_seq_ops = {
544 	.start	=	ac6_seq_start,
545 	.next	=	ac6_seq_next,
546 	.stop	=	ac6_seq_stop,
547 	.show	=	ac6_seq_show,
548 };
549 
550 static int ac6_seq_open(struct inode *inode, struct file *file)
551 {
552 	struct seq_file *seq;
553 	int rc = -ENOMEM;
554 	struct ac6_iter_state *s = kmalloc(sizeof(*s), GFP_KERNEL);
555 
556 	if (!s)
557 		goto out;
558 
559 	rc = seq_open(file, &ac6_seq_ops);
560 	if (rc)
561 		goto out_kfree;
562 
563 	seq = file->private_data;
564 	seq->private = s;
565 	memset(s, 0, sizeof(*s));
566 out:
567 	return rc;
568 out_kfree:
569 	kfree(s);
570 	goto out;
571 }
572 
573 static struct file_operations ac6_seq_fops = {
574 	.owner		=	THIS_MODULE,
575 	.open		=	ac6_seq_open,
576 	.read		=	seq_read,
577 	.llseek		=	seq_lseek,
578 	.release	=	seq_release_private,
579 };
580 
581 int __init ac6_proc_init(void)
582 {
583 	if (!proc_net_fops_create("anycast6", S_IRUGO, &ac6_seq_fops))
584 		return -ENOMEM;
585 
586 	return 0;
587 }
588 
589 void ac6_proc_exit(void)
590 {
591 	proc_net_remove("anycast6");
592 }
593 #endif
594 
595