xref: /openbmc/linux/net/ipv6/anycast.c (revision e190bfe5) 
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 #include <linux/slab.h>
33 
34 #include <net/net_namespace.h>
35 #include <net/sock.h>
36 #include <net/snmp.h>
37 
38 #include <net/ipv6.h>
39 #include <net/protocol.h>
40 #include <net/if_inet6.h>
41 #include <net/ndisc.h>
42 #include <net/addrconf.h>
43 #include <net/ip6_route.h>
44 
45 #include <net/checksum.h>
46 
47 static int ipv6_dev_ac_dec(struct net_device *dev, struct in6_addr *addr);
48 
49 /* Big ac list lock for all the sockets */
50 static DEFINE_RWLOCK(ipv6_sk_ac_lock);
51 
52 
53 /*
54  *	socket join an anycast group
55  */
56 
57 int ipv6_sock_ac_join(struct sock *sk, int ifindex, struct in6_addr *addr)
58 {
59 	struct ipv6_pinfo *np = inet6_sk(sk);
60 	struct net_device *dev = NULL;
61 	struct inet6_dev *idev;
62 	struct ipv6_ac_socklist *pac;
63 	struct net *net = sock_net(sk);
64 	int	ishost = !net->ipv6.devconf_all->forwarding;
65 	int	err = 0;
66 
67 	if (!capable(CAP_NET_ADMIN))
68 		return -EPERM;
69 	if (ipv6_addr_is_multicast(addr))
70 		return -EINVAL;
71 	if (ipv6_chk_addr(net, addr, NULL, 0))
72 		return -EINVAL;
73 
74 	pac = sock_kmalloc(sk, sizeof(struct ipv6_ac_socklist), GFP_KERNEL);
75 	if (pac == NULL)
76 		return -ENOMEM;
77 	pac->acl_next = NULL;
78 	ipv6_addr_copy(&pac->acl_addr, addr);
79 
80 	if (ifindex == 0) {
81 		struct rt6_info *rt;
82 
83 		rt = rt6_lookup(net, addr, NULL, 0, 0);
84 		if (rt) {
85 			dev = rt->rt6i_dev;
86 			dev_hold(dev);
87 			dst_release(&rt->u.dst);
88 		} else if (ishost) {
89 			err = -EADDRNOTAVAIL;
90 			goto out_free_pac;
91 		} else {
92 			/* router, no matching interface: just pick one */
93 
94 			dev = dev_get_by_flags(net, IFF_UP, IFF_UP|IFF_LOOPBACK);
95 		}
96 	} else
97 		dev = dev_get_by_index(net, ifindex);
98 
99 	if (dev == NULL) {
100 		err = -ENODEV;
101 		goto out_free_pac;
102 	}
103 
104 	idev = in6_dev_get(dev);
105 	if (!idev) {
106 		if (ifindex)
107 			err = -ENODEV;
108 		else
109 			err = -EADDRNOTAVAIL;
110 		goto out_dev_put;
111 	}
112 	/* reset ishost, now that we have a specific device */
113 	ishost = !idev->cnf.forwarding;
114 	in6_dev_put(idev);
115 
116 	pac->acl_ifindex = dev->ifindex;
117 
118 	/* XXX
119 	 * For hosts, allow link-local or matching prefix anycasts.
120 	 * This obviates the need for propagating anycast routes while
121 	 * still allowing some non-router anycast participation.
122 	 */
123 	if (!ipv6_chk_prefix(addr, dev)) {
124 		if (ishost)
125 			err = -EADDRNOTAVAIL;
126 		if (err)
127 			goto out_dev_put;
128 	}
129 
130 	err = ipv6_dev_ac_inc(dev, addr);
131 	if (err)
132 		goto out_dev_put;
133 
134 	write_lock_bh(&ipv6_sk_ac_lock);
135 	pac->acl_next = np->ipv6_ac_list;
136 	np->ipv6_ac_list = pac;
137 	write_unlock_bh(&ipv6_sk_ac_lock);
138 
139 	dev_put(dev);
140 
141 	return 0;
142 
143 out_dev_put:
144 	dev_put(dev);
145 out_free_pac:
146 	sock_kfree_s(sk, pac, sizeof(*pac));
147 	return err;
148 }
149 
150 /*
151  *	socket leave an anycast group
152  */
153 int ipv6_sock_ac_drop(struct sock *sk, int ifindex, struct in6_addr *addr)
154 {
155 	struct ipv6_pinfo *np = inet6_sk(sk);
156 	struct net_device *dev;
157 	struct ipv6_ac_socklist *pac, *prev_pac;
158 	struct net *net = sock_net(sk);
159 
160 	write_lock_bh(&ipv6_sk_ac_lock);
161 	prev_pac = NULL;
162 	for (pac = np->ipv6_ac_list; pac; pac = pac->acl_next) {
163 		if ((ifindex == 0 || pac->acl_ifindex == ifindex) &&
164 		     ipv6_addr_equal(&pac->acl_addr, addr))
165 			break;
166 		prev_pac = pac;
167 	}
168 	if (!pac) {
169 		write_unlock_bh(&ipv6_sk_ac_lock);
170 		return -ENOENT;
171 	}
172 	if (prev_pac)
173 		prev_pac->acl_next = pac->acl_next;
174 	else
175 		np->ipv6_ac_list = pac->acl_next;
176 
177 	write_unlock_bh(&ipv6_sk_ac_lock);
178 
179 	dev = dev_get_by_index(net, pac->acl_ifindex);
180 	if (dev) {
181 		ipv6_dev_ac_dec(dev, &pac->acl_addr);
182 		dev_put(dev);
183 	}
184 	sock_kfree_s(sk, pac, sizeof(*pac));
185 	return 0;
186 }
187 
188 void ipv6_sock_ac_close(struct sock *sk)
189 {
190 	struct ipv6_pinfo *np = inet6_sk(sk);
191 	struct net_device *dev = NULL;
192 	struct ipv6_ac_socklist *pac;
193 	struct net *net = sock_net(sk);
194 	int	prev_index;
195 
196 	write_lock_bh(&ipv6_sk_ac_lock);
197 	pac = np->ipv6_ac_list;
198 	np->ipv6_ac_list = NULL;
199 	write_unlock_bh(&ipv6_sk_ac_lock);
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 			if (dev)
207 				dev_put(dev);
208 			dev = dev_get_by_index(net, pac->acl_ifindex);
209 			prev_index = pac->acl_ifindex;
210 		}
211 		if (dev)
212 			ipv6_dev_ac_dec(dev, &pac->acl_addr);
213 		sock_kfree_s(sk, pac, sizeof(*pac));
214 		pac = next;
215 	}
216 	if (dev)
217 		dev_put(dev);
218 }
219 
220 #if 0
221 /* The function is not used, which is funny. Apparently, author
222  * supposed to use it to filter out datagrams inside udp/raw but forgot.
223  *
224  * It is OK, anycasts are not special comparing to delivery to unicasts.
225  */
226 
227 int inet6_ac_check(struct sock *sk, struct in6_addr *addr, int ifindex)
228 {
229 	struct ipv6_ac_socklist *pac;
230 	struct ipv6_pinfo *np = inet6_sk(sk);
231 	int	found;
232 
233 	found = 0;
234 	read_lock(&ipv6_sk_ac_lock);
235 	for (pac=np->ipv6_ac_list; pac; pac=pac->acl_next) {
236 		if (ifindex && pac->acl_ifindex != ifindex)
237 			continue;
238 		found = ipv6_addr_equal(&pac->acl_addr, addr);
239 		if (found)
240 			break;
241 	}
242 	read_unlock(&ipv6_sk_ac_lock);
243 
244 	return found;
245 }
246 
247 #endif
248 
249 static void aca_put(struct ifacaddr6 *ac)
250 {
251 	if (atomic_dec_and_test(&ac->aca_refcnt)) {
252 		in6_dev_put(ac->aca_idev);
253 		dst_release(&ac->aca_rt->u.dst);
254 		kfree(ac);
255 	}
256 }
257 
258 /*
259  *	device anycast group inc (add if not found)
260  */
261 int ipv6_dev_ac_inc(struct net_device *dev, struct in6_addr *addr)
262 {
263 	struct ifacaddr6 *aca;
264 	struct inet6_dev *idev;
265 	struct rt6_info *rt;
266 	int err;
267 
268 	idev = in6_dev_get(dev);
269 
270 	if (idev == NULL)
271 		return -EINVAL;
272 
273 	write_lock_bh(&idev->lock);
274 	if (idev->dead) {
275 		err = -ENODEV;
276 		goto out;
277 	}
278 
279 	for (aca = idev->ac_list; aca; aca = aca->aca_next) {
280 		if (ipv6_addr_equal(&aca->aca_addr, addr)) {
281 			aca->aca_users++;
282 			err = 0;
283 			goto out;
284 		}
285 	}
286 
287 	/*
288 	 *	not found: create a new one.
289 	 */
290 
291 	aca = kzalloc(sizeof(struct ifacaddr6), GFP_ATOMIC);
292 
293 	if (aca == NULL) {
294 		err = -ENOMEM;
295 		goto out;
296 	}
297 
298 	rt = addrconf_dst_alloc(idev, addr, 1);
299 	if (IS_ERR(rt)) {
300 		kfree(aca);
301 		err = PTR_ERR(rt);
302 		goto out;
303 	}
304 
305 	ipv6_addr_copy(&aca->aca_addr, addr);
306 	aca->aca_idev = idev;
307 	aca->aca_rt = rt;
308 	aca->aca_users = 1;
309 	/* aca_tstamp should be updated upon changes */
310 	aca->aca_cstamp = aca->aca_tstamp = jiffies;
311 	atomic_set(&aca->aca_refcnt, 2);
312 	spin_lock_init(&aca->aca_lock);
313 
314 	aca->aca_next = idev->ac_list;
315 	idev->ac_list = aca;
316 	write_unlock_bh(&idev->lock);
317 
318 	ip6_ins_rt(rt);
319 
320 	addrconf_join_solict(dev, &aca->aca_addr);
321 
322 	aca_put(aca);
323 	return 0;
324 out:
325 	write_unlock_bh(&idev->lock);
326 	in6_dev_put(idev);
327 	return err;
328 }
329 
330 /*
331  *	device anycast group decrement
332  */
333 int __ipv6_dev_ac_dec(struct inet6_dev *idev, struct in6_addr *addr)
334 {
335 	struct ifacaddr6 *aca, *prev_aca;
336 
337 	write_lock_bh(&idev->lock);
338 	prev_aca = NULL;
339 	for (aca = idev->ac_list; aca; aca = aca->aca_next) {
340 		if (ipv6_addr_equal(&aca->aca_addr, addr))
341 			break;
342 		prev_aca = aca;
343 	}
344 	if (!aca) {
345 		write_unlock_bh(&idev->lock);
346 		return -ENOENT;
347 	}
348 	if (--aca->aca_users > 0) {
349 		write_unlock_bh(&idev->lock);
350 		return 0;
351 	}
352 	if (prev_aca)
353 		prev_aca->aca_next = aca->aca_next;
354 	else
355 		idev->ac_list = aca->aca_next;
356 	write_unlock_bh(&idev->lock);
357 	addrconf_leave_solict(idev, &aca->aca_addr);
358 
359 	dst_hold(&aca->aca_rt->u.dst);
360 	ip6_del_rt(aca->aca_rt);
361 
362 	aca_put(aca);
363 	return 0;
364 }
365 
366 static int ipv6_dev_ac_dec(struct net_device *dev, struct in6_addr *addr)
367 {
368 	int ret;
369 	struct inet6_dev *idev = in6_dev_get(dev);
370 	if (idev == NULL)
371 		return -ENODEV;
372 	ret = __ipv6_dev_ac_dec(idev, addr);
373 	in6_dev_put(idev);
374 	return ret;
375 }
376 
377 /*
378  *	check if the interface has this anycast address
379  */
380 static int ipv6_chk_acast_dev(struct net_device *dev, struct in6_addr *addr)
381 {
382 	struct inet6_dev *idev;
383 	struct ifacaddr6 *aca;
384 
385 	idev = in6_dev_get(dev);
386 	if (idev) {
387 		read_lock_bh(&idev->lock);
388 		for (aca = idev->ac_list; aca; aca = aca->aca_next)
389 			if (ipv6_addr_equal(&aca->aca_addr, addr))
390 				break;
391 		read_unlock_bh(&idev->lock);
392 		in6_dev_put(idev);
393 		return aca != NULL;
394 	}
395 	return 0;
396 }
397 
398 /*
399  *	check if given interface (or any, if dev==0) has this anycast address
400  */
401 int ipv6_chk_acast_addr(struct net *net, struct net_device *dev,
402 			struct in6_addr *addr)
403 {
404 	int found = 0;
405 
406 	if (dev)
407 		return ipv6_chk_acast_dev(dev, addr);
408 	rcu_read_lock();
409 	for_each_netdev_rcu(net, dev)
410 		if (ipv6_chk_acast_dev(dev, addr)) {
411 			found = 1;
412 			break;
413 		}
414 	rcu_read_unlock();
415 	return found;
416 }
417 
418 
419 #ifdef CONFIG_PROC_FS
420 struct ac6_iter_state {
421 	struct seq_net_private p;
422 	struct net_device *dev;
423 	struct inet6_dev *idev;
424 };
425 
426 #define ac6_seq_private(seq)	((struct ac6_iter_state *)(seq)->private)
427 
428 static inline struct ifacaddr6 *ac6_get_first(struct seq_file *seq)
429 {
430 	struct ifacaddr6 *im = NULL;
431 	struct ac6_iter_state *state = ac6_seq_private(seq);
432 	struct net *net = seq_file_net(seq);
433 
434 	state->idev = NULL;
435 	for_each_netdev_rcu(net, state->dev) {
436 		struct inet6_dev *idev;
437 		idev = __in6_dev_get(state->dev);
438 		if (!idev)
439 			continue;
440 		read_lock_bh(&idev->lock);
441 		im = idev->ac_list;
442 		if (im) {
443 			state->idev = idev;
444 			break;
445 		}
446 		read_unlock_bh(&idev->lock);
447 	}
448 	return im;
449 }
450 
451 static struct ifacaddr6 *ac6_get_next(struct seq_file *seq, struct ifacaddr6 *im)
452 {
453 	struct ac6_iter_state *state = ac6_seq_private(seq);
454 
455 	im = im->aca_next;
456 	while (!im) {
457 		if (likely(state->idev != NULL))
458 			read_unlock_bh(&state->idev->lock);
459 
460 		state->dev = next_net_device_rcu(state->dev);
461 		if (!state->dev) {
462 			state->idev = NULL;
463 			break;
464 		}
465 		state->idev = __in6_dev_get(state->dev);
466 		if (!state->idev)
467 			continue;
468 		read_lock_bh(&state->idev->lock);
469 		im = state->idev->ac_list;
470 	}
471 	return im;
472 }
473 
474 static struct ifacaddr6 *ac6_get_idx(struct seq_file *seq, loff_t pos)
475 {
476 	struct ifacaddr6 *im = ac6_get_first(seq);
477 	if (im)
478 		while (pos && (im = ac6_get_next(seq, im)) != NULL)
479 			--pos;
480 	return pos ? NULL : im;
481 }
482 
483 static void *ac6_seq_start(struct seq_file *seq, loff_t *pos)
484 	__acquires(RCU)
485 {
486 	rcu_read_lock();
487 	return ac6_get_idx(seq, *pos);
488 }
489 
490 static void *ac6_seq_next(struct seq_file *seq, void *v, loff_t *pos)
491 {
492 	struct ifacaddr6 *im = ac6_get_next(seq, v);
493 
494 	++*pos;
495 	return im;
496 }
497 
498 static void ac6_seq_stop(struct seq_file *seq, void *v)
499 	__releases(RCU)
500 {
501 	struct ac6_iter_state *state = ac6_seq_private(seq);
502 
503 	if (likely(state->idev != NULL)) {
504 		read_unlock_bh(&state->idev->lock);
505 		state->idev = NULL;
506 	}
507 	rcu_read_unlock();
508 }
509 
510 static int ac6_seq_show(struct seq_file *seq, void *v)
511 {
512 	struct ifacaddr6 *im = (struct ifacaddr6 *)v;
513 	struct ac6_iter_state *state = ac6_seq_private(seq);
514 
515 	seq_printf(seq, "%-4d %-15s %pi6 %5d\n",
516 		   state->dev->ifindex, state->dev->name,
517 		   &im->aca_addr, im->aca_users);
518 	return 0;
519 }
520 
521 static const struct seq_operations ac6_seq_ops = {
522 	.start	=	ac6_seq_start,
523 	.next	=	ac6_seq_next,
524 	.stop	=	ac6_seq_stop,
525 	.show	=	ac6_seq_show,
526 };
527 
528 static int ac6_seq_open(struct inode *inode, struct file *file)
529 {
530 	return seq_open_net(inode, file, &ac6_seq_ops,
531 			    sizeof(struct ac6_iter_state));
532 }
533 
534 static const struct file_operations ac6_seq_fops = {
535 	.owner		=	THIS_MODULE,
536 	.open		=	ac6_seq_open,
537 	.read		=	seq_read,
538 	.llseek		=	seq_lseek,
539 	.release	=	seq_release_net,
540 };
541 
542 int __net_init ac6_proc_init(struct net *net)
543 {
544 	if (!proc_net_fops_create(net, "anycast6", S_IRUGO, &ac6_seq_fops))
545 		return -ENOMEM;
546 
547 	return 0;
548 }
549 
550 void ac6_proc_exit(struct net *net)
551 {
552 	proc_net_remove(net, "anycast6");
553 }
554 #endif
555 
556