xref: /openbmc/linux/net/ipv6/anycast.c (revision 61a3e166) 
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 	rcu_read_lock();
81 	if (ifindex == 0) {
82 		struct rt6_info *rt;
83 
84 		rt = rt6_lookup(net, addr, NULL, 0, 0);
85 		if (rt) {
86 			dev = rt->rt6i_dev;
87 			dst_release(&rt->dst);
88 		} else if (ishost) {
89 			err = -EADDRNOTAVAIL;
90 			goto error;
91 		} else {
92 			/* router, no matching interface: just pick one */
93 			dev = dev_get_by_flags_rcu(net, IFF_UP,
94 						   IFF_UP | IFF_LOOPBACK);
95 		}
96 	} else
97 		dev = dev_get_by_index_rcu(net, ifindex);
98 
99 	if (dev == NULL) {
100 		err = -ENODEV;
101 		goto error;
102 	}
103 
104 	idev = __in6_dev_get(dev);
105 	if (!idev) {
106 		if (ifindex)
107 			err = -ENODEV;
108 		else
109 			err = -EADDRNOTAVAIL;
110 		goto error;
111 	}
112 	/* reset ishost, now that we have a specific device */
113 	ishost = !idev->cnf.forwarding;
114 
115 	pac->acl_ifindex = dev->ifindex;
116 
117 	/* XXX
118 	 * For hosts, allow link-local or matching prefix anycasts.
119 	 * This obviates the need for propagating anycast routes while
120 	 * still allowing some non-router anycast participation.
121 	 */
122 	if (!ipv6_chk_prefix(addr, dev)) {
123 		if (ishost)
124 			err = -EADDRNOTAVAIL;
125 		if (err)
126 			goto error;
127 	}
128 
129 	err = ipv6_dev_ac_inc(dev, addr);
130 	if (!err) {
131 		write_lock_bh(&ipv6_sk_ac_lock);
132 		pac->acl_next = np->ipv6_ac_list;
133 		np->ipv6_ac_list = pac;
134 		write_unlock_bh(&ipv6_sk_ac_lock);
135 		pac = NULL;
136 	}
137 
138 error:
139 	rcu_read_unlock();
140 	if (pac)
141 		sock_kfree_s(sk, pac, sizeof(*pac));
142 	return err;
143 }
144 
145 /*
146  *	socket leave an anycast group
147  */
148 int ipv6_sock_ac_drop(struct sock *sk, int ifindex, struct in6_addr *addr)
149 {
150 	struct ipv6_pinfo *np = inet6_sk(sk);
151 	struct net_device *dev;
152 	struct ipv6_ac_socklist *pac, *prev_pac;
153 	struct net *net = sock_net(sk);
154 
155 	write_lock_bh(&ipv6_sk_ac_lock);
156 	prev_pac = NULL;
157 	for (pac = np->ipv6_ac_list; pac; pac = pac->acl_next) {
158 		if ((ifindex == 0 || pac->acl_ifindex == ifindex) &&
159 		     ipv6_addr_equal(&pac->acl_addr, addr))
160 			break;
161 		prev_pac = pac;
162 	}
163 	if (!pac) {
164 		write_unlock_bh(&ipv6_sk_ac_lock);
165 		return -ENOENT;
166 	}
167 	if (prev_pac)
168 		prev_pac->acl_next = pac->acl_next;
169 	else
170 		np->ipv6_ac_list = pac->acl_next;
171 
172 	write_unlock_bh(&ipv6_sk_ac_lock);
173 
174 	rcu_read_lock();
175 	dev = dev_get_by_index_rcu(net, pac->acl_ifindex);
176 	if (dev)
177 		ipv6_dev_ac_dec(dev, &pac->acl_addr);
178 	rcu_read_unlock();
179 
180 	sock_kfree_s(sk, pac, sizeof(*pac));
181 	return 0;
182 }
183 
184 void ipv6_sock_ac_close(struct sock *sk)
185 {
186 	struct ipv6_pinfo *np = inet6_sk(sk);
187 	struct net_device *dev = NULL;
188 	struct ipv6_ac_socklist *pac;
189 	struct net *net = sock_net(sk);
190 	int	prev_index;
191 
192 	write_lock_bh(&ipv6_sk_ac_lock);
193 	pac = np->ipv6_ac_list;
194 	np->ipv6_ac_list = NULL;
195 	write_unlock_bh(&ipv6_sk_ac_lock);
196 
197 	prev_index = 0;
198 	rcu_read_lock();
199 	while (pac) {
200 		struct ipv6_ac_socklist *next = pac->acl_next;
201 
202 		if (pac->acl_ifindex != prev_index) {
203 			dev = dev_get_by_index_rcu(net, pac->acl_ifindex);
204 			prev_index = pac->acl_ifindex;
205 		}
206 		if (dev)
207 			ipv6_dev_ac_dec(dev, &pac->acl_addr);
208 		sock_kfree_s(sk, pac, sizeof(*pac));
209 		pac = next;
210 	}
211 	rcu_read_unlock();
212 }
213 
214 #if 0
215 /* The function is not used, which is funny. Apparently, author
216  * supposed to use it to filter out datagrams inside udp/raw but forgot.
217  *
218  * It is OK, anycasts are not special comparing to delivery to unicasts.
219  */
220 
221 int inet6_ac_check(struct sock *sk, struct in6_addr *addr, int ifindex)
222 {
223 	struct ipv6_ac_socklist *pac;
224 	struct ipv6_pinfo *np = inet6_sk(sk);
225 	int	found;
226 
227 	found = 0;
228 	read_lock(&ipv6_sk_ac_lock);
229 	for (pac=np->ipv6_ac_list; pac; pac=pac->acl_next) {
230 		if (ifindex && pac->acl_ifindex != ifindex)
231 			continue;
232 		found = ipv6_addr_equal(&pac->acl_addr, addr);
233 		if (found)
234 			break;
235 	}
236 	read_unlock(&ipv6_sk_ac_lock);
237 
238 	return found;
239 }
240 
241 #endif
242 
243 static void aca_put(struct ifacaddr6 *ac)
244 {
245 	if (atomic_dec_and_test(&ac->aca_refcnt)) {
246 		in6_dev_put(ac->aca_idev);
247 		dst_release(&ac->aca_rt->dst);
248 		kfree(ac);
249 	}
250 }
251 
252 /*
253  *	device anycast group inc (add if not found)
254  */
255 int ipv6_dev_ac_inc(struct net_device *dev, struct in6_addr *addr)
256 {
257 	struct ifacaddr6 *aca;
258 	struct inet6_dev *idev;
259 	struct rt6_info *rt;
260 	int err;
261 
262 	idev = in6_dev_get(dev);
263 
264 	if (idev == NULL)
265 		return -EINVAL;
266 
267 	write_lock_bh(&idev->lock);
268 	if (idev->dead) {
269 		err = -ENODEV;
270 		goto out;
271 	}
272 
273 	for (aca = idev->ac_list; aca; aca = aca->aca_next) {
274 		if (ipv6_addr_equal(&aca->aca_addr, addr)) {
275 			aca->aca_users++;
276 			err = 0;
277 			goto out;
278 		}
279 	}
280 
281 	/*
282 	 *	not found: create a new one.
283 	 */
284 
285 	aca = kzalloc(sizeof(struct ifacaddr6), GFP_ATOMIC);
286 
287 	if (aca == NULL) {
288 		err = -ENOMEM;
289 		goto out;
290 	}
291 
292 	rt = addrconf_dst_alloc(idev, addr, 1);
293 	if (IS_ERR(rt)) {
294 		kfree(aca);
295 		err = PTR_ERR(rt);
296 		goto out;
297 	}
298 
299 	ipv6_addr_copy(&aca->aca_addr, addr);
300 	aca->aca_idev = idev;
301 	aca->aca_rt = rt;
302 	aca->aca_users = 1;
303 	/* aca_tstamp should be updated upon changes */
304 	aca->aca_cstamp = aca->aca_tstamp = jiffies;
305 	atomic_set(&aca->aca_refcnt, 2);
306 	spin_lock_init(&aca->aca_lock);
307 
308 	aca->aca_next = idev->ac_list;
309 	idev->ac_list = aca;
310 	write_unlock_bh(&idev->lock);
311 
312 	ip6_ins_rt(rt);
313 
314 	addrconf_join_solict(dev, &aca->aca_addr);
315 
316 	aca_put(aca);
317 	return 0;
318 out:
319 	write_unlock_bh(&idev->lock);
320 	in6_dev_put(idev);
321 	return err;
322 }
323 
324 /*
325  *	device anycast group decrement
326  */
327 int __ipv6_dev_ac_dec(struct inet6_dev *idev, struct in6_addr *addr)
328 {
329 	struct ifacaddr6 *aca, *prev_aca;
330 
331 	write_lock_bh(&idev->lock);
332 	prev_aca = NULL;
333 	for (aca = idev->ac_list; aca; aca = aca->aca_next) {
334 		if (ipv6_addr_equal(&aca->aca_addr, addr))
335 			break;
336 		prev_aca = aca;
337 	}
338 	if (!aca) {
339 		write_unlock_bh(&idev->lock);
340 		return -ENOENT;
341 	}
342 	if (--aca->aca_users > 0) {
343 		write_unlock_bh(&idev->lock);
344 		return 0;
345 	}
346 	if (prev_aca)
347 		prev_aca->aca_next = aca->aca_next;
348 	else
349 		idev->ac_list = aca->aca_next;
350 	write_unlock_bh(&idev->lock);
351 	addrconf_leave_solict(idev, &aca->aca_addr);
352 
353 	dst_hold(&aca->aca_rt->dst);
354 	ip6_del_rt(aca->aca_rt);
355 
356 	aca_put(aca);
357 	return 0;
358 }
359 
360 /* called with rcu_read_lock() */
361 static int ipv6_dev_ac_dec(struct net_device *dev, struct in6_addr *addr)
362 {
363 	struct inet6_dev *idev = __in6_dev_get(dev);
364 
365 	if (idev == NULL)
366 		return -ENODEV;
367 	return __ipv6_dev_ac_dec(idev, addr);
368 }
369 
370 /*
371  *	check if the interface has this anycast address
372  *	called with rcu_read_lock()
373  */
374 static int ipv6_chk_acast_dev(struct net_device *dev, struct in6_addr *addr)
375 {
376 	struct inet6_dev *idev;
377 	struct ifacaddr6 *aca;
378 
379 	idev = __in6_dev_get(dev);
380 	if (idev) {
381 		read_lock_bh(&idev->lock);
382 		for (aca = idev->ac_list; aca; aca = aca->aca_next)
383 			if (ipv6_addr_equal(&aca->aca_addr, addr))
384 				break;
385 		read_unlock_bh(&idev->lock);
386 		return aca != NULL;
387 	}
388 	return 0;
389 }
390 
391 /*
392  *	check if given interface (or any, if dev==0) has this anycast address
393  */
394 int ipv6_chk_acast_addr(struct net *net, struct net_device *dev,
395 			struct in6_addr *addr)
396 {
397 	int found = 0;
398 
399 	rcu_read_lock();
400 	if (dev)
401 		found = ipv6_chk_acast_dev(dev, addr);
402 	else
403 		for_each_netdev_rcu(net, dev)
404 			if (ipv6_chk_acast_dev(dev, addr)) {
405 				found = 1;
406 				break;
407 			}
408 	rcu_read_unlock();
409 	return found;
410 }
411 
412 
413 #ifdef CONFIG_PROC_FS
414 struct ac6_iter_state {
415 	struct seq_net_private p;
416 	struct net_device *dev;
417 	struct inet6_dev *idev;
418 };
419 
420 #define ac6_seq_private(seq)	((struct ac6_iter_state *)(seq)->private)
421 
422 static inline struct ifacaddr6 *ac6_get_first(struct seq_file *seq)
423 {
424 	struct ifacaddr6 *im = NULL;
425 	struct ac6_iter_state *state = ac6_seq_private(seq);
426 	struct net *net = seq_file_net(seq);
427 
428 	state->idev = NULL;
429 	for_each_netdev_rcu(net, state->dev) {
430 		struct inet6_dev *idev;
431 		idev = __in6_dev_get(state->dev);
432 		if (!idev)
433 			continue;
434 		read_lock_bh(&idev->lock);
435 		im = idev->ac_list;
436 		if (im) {
437 			state->idev = idev;
438 			break;
439 		}
440 		read_unlock_bh(&idev->lock);
441 	}
442 	return im;
443 }
444 
445 static struct ifacaddr6 *ac6_get_next(struct seq_file *seq, struct ifacaddr6 *im)
446 {
447 	struct ac6_iter_state *state = ac6_seq_private(seq);
448 
449 	im = im->aca_next;
450 	while (!im) {
451 		if (likely(state->idev != NULL))
452 			read_unlock_bh(&state->idev->lock);
453 
454 		state->dev = next_net_device_rcu(state->dev);
455 		if (!state->dev) {
456 			state->idev = NULL;
457 			break;
458 		}
459 		state->idev = __in6_dev_get(state->dev);
460 		if (!state->idev)
461 			continue;
462 		read_lock_bh(&state->idev->lock);
463 		im = state->idev->ac_list;
464 	}
465 	return im;
466 }
467 
468 static struct ifacaddr6 *ac6_get_idx(struct seq_file *seq, loff_t pos)
469 {
470 	struct ifacaddr6 *im = ac6_get_first(seq);
471 	if (im)
472 		while (pos && (im = ac6_get_next(seq, im)) != NULL)
473 			--pos;
474 	return pos ? NULL : im;
475 }
476 
477 static void *ac6_seq_start(struct seq_file *seq, loff_t *pos)
478 	__acquires(RCU)
479 {
480 	rcu_read_lock();
481 	return ac6_get_idx(seq, *pos);
482 }
483 
484 static void *ac6_seq_next(struct seq_file *seq, void *v, loff_t *pos)
485 {
486 	struct ifacaddr6 *im = ac6_get_next(seq, v);
487 
488 	++*pos;
489 	return im;
490 }
491 
492 static void ac6_seq_stop(struct seq_file *seq, void *v)
493 	__releases(RCU)
494 {
495 	struct ac6_iter_state *state = ac6_seq_private(seq);
496 
497 	if (likely(state->idev != NULL)) {
498 		read_unlock_bh(&state->idev->lock);
499 		state->idev = NULL;
500 	}
501 	rcu_read_unlock();
502 }
503 
504 static int ac6_seq_show(struct seq_file *seq, void *v)
505 {
506 	struct ifacaddr6 *im = (struct ifacaddr6 *)v;
507 	struct ac6_iter_state *state = ac6_seq_private(seq);
508 
509 	seq_printf(seq, "%-4d %-15s %pi6 %5d\n",
510 		   state->dev->ifindex, state->dev->name,
511 		   &im->aca_addr, im->aca_users);
512 	return 0;
513 }
514 
515 static const struct seq_operations ac6_seq_ops = {
516 	.start	=	ac6_seq_start,
517 	.next	=	ac6_seq_next,
518 	.stop	=	ac6_seq_stop,
519 	.show	=	ac6_seq_show,
520 };
521 
522 static int ac6_seq_open(struct inode *inode, struct file *file)
523 {
524 	return seq_open_net(inode, file, &ac6_seq_ops,
525 			    sizeof(struct ac6_iter_state));
526 }
527 
528 static const struct file_operations ac6_seq_fops = {
529 	.owner		=	THIS_MODULE,
530 	.open		=	ac6_seq_open,
531 	.read		=	seq_read,
532 	.llseek		=	seq_lseek,
533 	.release	=	seq_release_net,
534 };
535 
536 int __net_init ac6_proc_init(struct net *net)
537 {
538 	if (!proc_net_fops_create(net, "anycast6", S_IRUGO, &ac6_seq_fops))
539 		return -ENOMEM;
540 
541 	return 0;
542 }
543 
544 void ac6_proc_exit(struct net *net)
545 {
546 	proc_net_remove(net, "anycast6");
547 }
548 #endif
549 
550