xref: /openbmc/linux/net/ipv6/anycast.c (revision 1c2dd16a) 
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, const struct in6_addr *addr);
48 
49 /*
50  *	socket join an anycast group
51  */
52 
53 int ipv6_sock_ac_join(struct sock *sk, int ifindex, const struct in6_addr *addr)
54 {
55 	struct ipv6_pinfo *np = inet6_sk(sk);
56 	struct net_device *dev = NULL;
57 	struct inet6_dev *idev;
58 	struct ipv6_ac_socklist *pac;
59 	struct net *net = sock_net(sk);
60 	int	ishost = !net->ipv6.devconf_all->forwarding;
61 	int	err = 0;
62 
63 	ASSERT_RTNL();
64 
65 	if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
66 		return -EPERM;
67 	if (ipv6_addr_is_multicast(addr))
68 		return -EINVAL;
69 	if (ipv6_chk_addr(net, addr, NULL, 0))
70 		return -EINVAL;
71 
72 	pac = sock_kmalloc(sk, sizeof(struct ipv6_ac_socklist), GFP_KERNEL);
73 	if (!pac)
74 		return -ENOMEM;
75 	pac->acl_next = NULL;
76 	pac->acl_addr = *addr;
77 
78 	if (ifindex == 0) {
79 		struct rt6_info *rt;
80 
81 		rt = rt6_lookup(net, addr, NULL, 0, 0);
82 		if (rt) {
83 			dev = rt->dst.dev;
84 			ip6_rt_put(rt);
85 		} else if (ishost) {
86 			err = -EADDRNOTAVAIL;
87 			goto error;
88 		} else {
89 			/* router, no matching interface: just pick one */
90 			dev = __dev_get_by_flags(net, IFF_UP,
91 						 IFF_UP | IFF_LOOPBACK);
92 		}
93 	} else
94 		dev = __dev_get_by_index(net, ifindex);
95 
96 	if (!dev) {
97 		err = -ENODEV;
98 		goto error;
99 	}
100 
101 	idev = __in6_dev_get(dev);
102 	if (!idev) {
103 		if (ifindex)
104 			err = -ENODEV;
105 		else
106 			err = -EADDRNOTAVAIL;
107 		goto error;
108 	}
109 	/* reset ishost, now that we have a specific device */
110 	ishost = !idev->cnf.forwarding;
111 
112 	pac->acl_ifindex = dev->ifindex;
113 
114 	/* XXX
115 	 * For hosts, allow link-local or matching prefix anycasts.
116 	 * This obviates the need for propagating anycast routes while
117 	 * still allowing some non-router anycast participation.
118 	 */
119 	if (!ipv6_chk_prefix(addr, dev)) {
120 		if (ishost)
121 			err = -EADDRNOTAVAIL;
122 		if (err)
123 			goto error;
124 	}
125 
126 	err = __ipv6_dev_ac_inc(idev, addr);
127 	if (!err) {
128 		pac->acl_next = np->ipv6_ac_list;
129 		np->ipv6_ac_list = pac;
130 		pac = NULL;
131 	}
132 
133 error:
134 	if (pac)
135 		sock_kfree_s(sk, pac, sizeof(*pac));
136 	return err;
137 }
138 
139 /*
140  *	socket leave an anycast group
141  */
142 int ipv6_sock_ac_drop(struct sock *sk, int ifindex, const struct in6_addr *addr)
143 {
144 	struct ipv6_pinfo *np = inet6_sk(sk);
145 	struct net_device *dev;
146 	struct ipv6_ac_socklist *pac, *prev_pac;
147 	struct net *net = sock_net(sk);
148 
149 	ASSERT_RTNL();
150 
151 	prev_pac = NULL;
152 	for (pac = np->ipv6_ac_list; pac; pac = pac->acl_next) {
153 		if ((ifindex == 0 || pac->acl_ifindex == ifindex) &&
154 		     ipv6_addr_equal(&pac->acl_addr, addr))
155 			break;
156 		prev_pac = pac;
157 	}
158 	if (!pac)
159 		return -ENOENT;
160 	if (prev_pac)
161 		prev_pac->acl_next = pac->acl_next;
162 	else
163 		np->ipv6_ac_list = pac->acl_next;
164 
165 	dev = __dev_get_by_index(net, pac->acl_ifindex);
166 	if (dev)
167 		ipv6_dev_ac_dec(dev, &pac->acl_addr);
168 
169 	sock_kfree_s(sk, pac, sizeof(*pac));
170 	return 0;
171 }
172 
173 void ipv6_sock_ac_close(struct sock *sk)
174 {
175 	struct ipv6_pinfo *np = inet6_sk(sk);
176 	struct net_device *dev = NULL;
177 	struct ipv6_ac_socklist *pac;
178 	struct net *net = sock_net(sk);
179 	int	prev_index;
180 
181 	if (!np->ipv6_ac_list)
182 		return;
183 
184 	rtnl_lock();
185 	pac = np->ipv6_ac_list;
186 	np->ipv6_ac_list = NULL;
187 
188 	prev_index = 0;
189 	while (pac) {
190 		struct ipv6_ac_socklist *next = pac->acl_next;
191 
192 		if (pac->acl_ifindex != prev_index) {
193 			dev = __dev_get_by_index(net, pac->acl_ifindex);
194 			prev_index = pac->acl_ifindex;
195 		}
196 		if (dev)
197 			ipv6_dev_ac_dec(dev, &pac->acl_addr);
198 		sock_kfree_s(sk, pac, sizeof(*pac));
199 		pac = next;
200 	}
201 	rtnl_unlock();
202 }
203 
204 static void aca_get(struct ifacaddr6 *aca)
205 {
206 	atomic_inc(&aca->aca_refcnt);
207 }
208 
209 static void aca_put(struct ifacaddr6 *ac)
210 {
211 	if (atomic_dec_and_test(&ac->aca_refcnt)) {
212 		in6_dev_put(ac->aca_idev);
213 		dst_release(&ac->aca_rt->dst);
214 		kfree(ac);
215 	}
216 }
217 
218 static struct ifacaddr6 *aca_alloc(struct rt6_info *rt,
219 				   const struct in6_addr *addr)
220 {
221 	struct inet6_dev *idev = rt->rt6i_idev;
222 	struct ifacaddr6 *aca;
223 
224 	aca = kzalloc(sizeof(*aca), GFP_ATOMIC);
225 	if (!aca)
226 		return NULL;
227 
228 	aca->aca_addr = *addr;
229 	in6_dev_hold(idev);
230 	aca->aca_idev = idev;
231 	aca->aca_rt = rt;
232 	aca->aca_users = 1;
233 	/* aca_tstamp should be updated upon changes */
234 	aca->aca_cstamp = aca->aca_tstamp = jiffies;
235 	atomic_set(&aca->aca_refcnt, 1);
236 
237 	return aca;
238 }
239 
240 /*
241  *	device anycast group inc (add if not found)
242  */
243 int __ipv6_dev_ac_inc(struct inet6_dev *idev, const struct in6_addr *addr)
244 {
245 	struct ifacaddr6 *aca;
246 	struct rt6_info *rt;
247 	int err;
248 
249 	ASSERT_RTNL();
250 
251 	write_lock_bh(&idev->lock);
252 	if (idev->dead) {
253 		err = -ENODEV;
254 		goto out;
255 	}
256 
257 	for (aca = idev->ac_list; aca; aca = aca->aca_next) {
258 		if (ipv6_addr_equal(&aca->aca_addr, addr)) {
259 			aca->aca_users++;
260 			err = 0;
261 			goto out;
262 		}
263 	}
264 
265 	rt = addrconf_dst_alloc(idev, addr, true);
266 	if (IS_ERR(rt)) {
267 		err = PTR_ERR(rt);
268 		goto out;
269 	}
270 	aca = aca_alloc(rt, addr);
271 	if (!aca) {
272 		ip6_rt_put(rt);
273 		err = -ENOMEM;
274 		goto out;
275 	}
276 
277 	aca->aca_next = idev->ac_list;
278 	idev->ac_list = aca;
279 
280 	/* Hold this for addrconf_join_solict() below before we unlock,
281 	 * it is already exposed via idev->ac_list.
282 	 */
283 	aca_get(aca);
284 	write_unlock_bh(&idev->lock);
285 
286 	ip6_ins_rt(rt);
287 
288 	addrconf_join_solict(idev->dev, &aca->aca_addr);
289 
290 	aca_put(aca);
291 	return 0;
292 out:
293 	write_unlock_bh(&idev->lock);
294 	return err;
295 }
296 
297 /*
298  *	device anycast group decrement
299  */
300 int __ipv6_dev_ac_dec(struct inet6_dev *idev, const struct in6_addr *addr)
301 {
302 	struct ifacaddr6 *aca, *prev_aca;
303 
304 	ASSERT_RTNL();
305 
306 	write_lock_bh(&idev->lock);
307 	prev_aca = NULL;
308 	for (aca = idev->ac_list; aca; aca = aca->aca_next) {
309 		if (ipv6_addr_equal(&aca->aca_addr, addr))
310 			break;
311 		prev_aca = aca;
312 	}
313 	if (!aca) {
314 		write_unlock_bh(&idev->lock);
315 		return -ENOENT;
316 	}
317 	if (--aca->aca_users > 0) {
318 		write_unlock_bh(&idev->lock);
319 		return 0;
320 	}
321 	if (prev_aca)
322 		prev_aca->aca_next = aca->aca_next;
323 	else
324 		idev->ac_list = aca->aca_next;
325 	write_unlock_bh(&idev->lock);
326 	addrconf_leave_solict(idev, &aca->aca_addr);
327 
328 	dst_hold(&aca->aca_rt->dst);
329 	ip6_del_rt(aca->aca_rt);
330 
331 	aca_put(aca);
332 	return 0;
333 }
334 
335 /* called with rtnl_lock() */
336 static int ipv6_dev_ac_dec(struct net_device *dev, const struct in6_addr *addr)
337 {
338 	struct inet6_dev *idev = __in6_dev_get(dev);
339 
340 	if (!idev)
341 		return -ENODEV;
342 	return __ipv6_dev_ac_dec(idev, addr);
343 }
344 
345 void ipv6_ac_destroy_dev(struct inet6_dev *idev)
346 {
347 	struct ifacaddr6 *aca;
348 
349 	write_lock_bh(&idev->lock);
350 	while ((aca = idev->ac_list) != NULL) {
351 		idev->ac_list = aca->aca_next;
352 		write_unlock_bh(&idev->lock);
353 
354 		addrconf_leave_solict(idev, &aca->aca_addr);
355 
356 		dst_hold(&aca->aca_rt->dst);
357 		ip6_del_rt(aca->aca_rt);
358 
359 		aca_put(aca);
360 
361 		write_lock_bh(&idev->lock);
362 	}
363 	write_unlock_bh(&idev->lock);
364 }
365 
366 /*
367  *	check if the interface has this anycast address
368  *	called with rcu_read_lock()
369  */
370 static bool ipv6_chk_acast_dev(struct net_device *dev, const struct in6_addr *addr)
371 {
372 	struct inet6_dev *idev;
373 	struct ifacaddr6 *aca;
374 
375 	idev = __in6_dev_get(dev);
376 	if (idev) {
377 		read_lock_bh(&idev->lock);
378 		for (aca = idev->ac_list; aca; aca = aca->aca_next)
379 			if (ipv6_addr_equal(&aca->aca_addr, addr))
380 				break;
381 		read_unlock_bh(&idev->lock);
382 		return aca != NULL;
383 	}
384 	return false;
385 }
386 
387 /*
388  *	check if given interface (or any, if dev==0) has this anycast address
389  */
390 bool ipv6_chk_acast_addr(struct net *net, struct net_device *dev,
391 			 const struct in6_addr *addr)
392 {
393 	bool found = false;
394 
395 	rcu_read_lock();
396 	if (dev)
397 		found = ipv6_chk_acast_dev(dev, addr);
398 	else
399 		for_each_netdev_rcu(net, dev)
400 			if (ipv6_chk_acast_dev(dev, addr)) {
401 				found = true;
402 				break;
403 			}
404 	rcu_read_unlock();
405 	return found;
406 }
407 
408 /*	check if this anycast address is link-local on given interface or
409  *	is global
410  */
411 bool ipv6_chk_acast_addr_src(struct net *net, struct net_device *dev,
412 			     const struct in6_addr *addr)
413 {
414 	return ipv6_chk_acast_addr(net,
415 				   (ipv6_addr_type(addr) & IPV6_ADDR_LINKLOCAL ?
416 				    dev : NULL),
417 				   addr);
418 }
419 
420 #ifdef CONFIG_PROC_FS
421 struct ac6_iter_state {
422 	struct seq_net_private p;
423 	struct net_device *dev;
424 	struct inet6_dev *idev;
425 };
426 
427 #define ac6_seq_private(seq)	((struct ac6_iter_state *)(seq)->private)
428 
429 static inline struct ifacaddr6 *ac6_get_first(struct seq_file *seq)
430 {
431 	struct ifacaddr6 *im = NULL;
432 	struct ac6_iter_state *state = ac6_seq_private(seq);
433 	struct net *net = seq_file_net(seq);
434 
435 	state->idev = NULL;
436 	for_each_netdev_rcu(net, state->dev) {
437 		struct inet6_dev *idev;
438 		idev = __in6_dev_get(state->dev);
439 		if (!idev)
440 			continue;
441 		read_lock_bh(&idev->lock);
442 		im = idev->ac_list;
443 		if (im) {
444 			state->idev = idev;
445 			break;
446 		}
447 		read_unlock_bh(&idev->lock);
448 	}
449 	return im;
450 }
451 
452 static struct ifacaddr6 *ac6_get_next(struct seq_file *seq, struct ifacaddr6 *im)
453 {
454 	struct ac6_iter_state *state = ac6_seq_private(seq);
455 
456 	im = im->aca_next;
457 	while (!im) {
458 		if (likely(state->idev != NULL))
459 			read_unlock_bh(&state->idev->lock);
460 
461 		state->dev = next_net_device_rcu(state->dev);
462 		if (!state->dev) {
463 			state->idev = NULL;
464 			break;
465 		}
466 		state->idev = __in6_dev_get(state->dev);
467 		if (!state->idev)
468 			continue;
469 		read_lock_bh(&state->idev->lock);
470 		im = state->idev->ac_list;
471 	}
472 	return im;
473 }
474 
475 static struct ifacaddr6 *ac6_get_idx(struct seq_file *seq, loff_t pos)
476 {
477 	struct ifacaddr6 *im = ac6_get_first(seq);
478 	if (im)
479 		while (pos && (im = ac6_get_next(seq, im)) != NULL)
480 			--pos;
481 	return pos ? NULL : im;
482 }
483 
484 static void *ac6_seq_start(struct seq_file *seq, loff_t *pos)
485 	__acquires(RCU)
486 {
487 	rcu_read_lock();
488 	return ac6_get_idx(seq, *pos);
489 }
490 
491 static void *ac6_seq_next(struct seq_file *seq, void *v, loff_t *pos)
492 {
493 	struct ifacaddr6 *im = ac6_get_next(seq, v);
494 
495 	++*pos;
496 	return im;
497 }
498 
499 static void ac6_seq_stop(struct seq_file *seq, void *v)
500 	__releases(RCU)
501 {
502 	struct ac6_iter_state *state = ac6_seq_private(seq);
503 
504 	if (likely(state->idev != NULL)) {
505 		read_unlock_bh(&state->idev->lock);
506 		state->idev = NULL;
507 	}
508 	rcu_read_unlock();
509 }
510 
511 static int ac6_seq_show(struct seq_file *seq, void *v)
512 {
513 	struct ifacaddr6 *im = (struct ifacaddr6 *)v;
514 	struct ac6_iter_state *state = ac6_seq_private(seq);
515 
516 	seq_printf(seq, "%-4d %-15s %pi6 %5d\n",
517 		   state->dev->ifindex, state->dev->name,
518 		   &im->aca_addr, im->aca_users);
519 	return 0;
520 }
521 
522 static const struct seq_operations ac6_seq_ops = {
523 	.start	=	ac6_seq_start,
524 	.next	=	ac6_seq_next,
525 	.stop	=	ac6_seq_stop,
526 	.show	=	ac6_seq_show,
527 };
528 
529 static int ac6_seq_open(struct inode *inode, struct file *file)
530 {
531 	return seq_open_net(inode, file, &ac6_seq_ops,
532 			    sizeof(struct ac6_iter_state));
533 }
534 
535 static const struct file_operations ac6_seq_fops = {
536 	.owner		=	THIS_MODULE,
537 	.open		=	ac6_seq_open,
538 	.read		=	seq_read,
539 	.llseek		=	seq_lseek,
540 	.release	=	seq_release_net,
541 };
542 
543 int __net_init ac6_proc_init(struct net *net)
544 {
545 	if (!proc_create("anycast6", S_IRUGO, net->proc_net, &ac6_seq_fops))
546 		return -ENOMEM;
547 
548 	return 0;
549 }
550 
551 void ac6_proc_exit(struct net *net)
552 {
553 	remove_proc_entry("anycast6", net->proc_net);
554 }
555 #endif
556 
557