xref: /openbmc/linux/net/ipv6/anycast.c (revision 94c7b6fc) 
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 /* Big ac list lock for all the sockets */
50 static DEFINE_SPINLOCK(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, const 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 (!ns_capable(net->user_ns, 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 	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->dst.dev;
87 			ip6_rt_put(rt);
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 		spin_lock_bh(&ipv6_sk_ac_lock);
132 		pac->acl_next = np->ipv6_ac_list;
133 		np->ipv6_ac_list = pac;
134 		spin_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, const 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 	spin_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 		spin_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 	spin_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 	if (!np->ipv6_ac_list)
193 		return;
194 
195 	spin_lock_bh(&ipv6_sk_ac_lock);
196 	pac = np->ipv6_ac_list;
197 	np->ipv6_ac_list = NULL;
198 	spin_unlock_bh(&ipv6_sk_ac_lock);
199 
200 	prev_index = 0;
201 	rcu_read_lock();
202 	while (pac) {
203 		struct ipv6_ac_socklist *next = pac->acl_next;
204 
205 		if (pac->acl_ifindex != prev_index) {
206 			dev = dev_get_by_index_rcu(net, pac->acl_ifindex);
207 			prev_index = pac->acl_ifindex;
208 		}
209 		if (dev)
210 			ipv6_dev_ac_dec(dev, &pac->acl_addr);
211 		sock_kfree_s(sk, pac, sizeof(*pac));
212 		pac = next;
213 	}
214 	rcu_read_unlock();
215 }
216 
217 static void aca_put(struct ifacaddr6 *ac)
218 {
219 	if (atomic_dec_and_test(&ac->aca_refcnt)) {
220 		in6_dev_put(ac->aca_idev);
221 		dst_release(&ac->aca_rt->dst);
222 		kfree(ac);
223 	}
224 }
225 
226 /*
227  *	device anycast group inc (add if not found)
228  */
229 int ipv6_dev_ac_inc(struct net_device *dev, const struct in6_addr *addr)
230 {
231 	struct ifacaddr6 *aca;
232 	struct inet6_dev *idev;
233 	struct rt6_info *rt;
234 	int err;
235 
236 	idev = in6_dev_get(dev);
237 
238 	if (idev == NULL)
239 		return -EINVAL;
240 
241 	write_lock_bh(&idev->lock);
242 	if (idev->dead) {
243 		err = -ENODEV;
244 		goto out;
245 	}
246 
247 	for (aca = idev->ac_list; aca; aca = aca->aca_next) {
248 		if (ipv6_addr_equal(&aca->aca_addr, addr)) {
249 			aca->aca_users++;
250 			err = 0;
251 			goto out;
252 		}
253 	}
254 
255 	/*
256 	 *	not found: create a new one.
257 	 */
258 
259 	aca = kzalloc(sizeof(struct ifacaddr6), GFP_ATOMIC);
260 
261 	if (aca == NULL) {
262 		err = -ENOMEM;
263 		goto out;
264 	}
265 
266 	rt = addrconf_dst_alloc(idev, addr, true);
267 	if (IS_ERR(rt)) {
268 		kfree(aca);
269 		err = PTR_ERR(rt);
270 		goto out;
271 	}
272 
273 	aca->aca_addr = *addr;
274 	aca->aca_idev = idev;
275 	aca->aca_rt = rt;
276 	aca->aca_users = 1;
277 	/* aca_tstamp should be updated upon changes */
278 	aca->aca_cstamp = aca->aca_tstamp = jiffies;
279 	atomic_set(&aca->aca_refcnt, 2);
280 	spin_lock_init(&aca->aca_lock);
281 
282 	aca->aca_next = idev->ac_list;
283 	idev->ac_list = aca;
284 	write_unlock_bh(&idev->lock);
285 
286 	ip6_ins_rt(rt);
287 
288 	addrconf_join_solict(dev, &aca->aca_addr);
289 
290 	aca_put(aca);
291 	return 0;
292 out:
293 	write_unlock_bh(&idev->lock);
294 	in6_dev_put(idev);
295 	return err;
296 }
297 
298 /*
299  *	device anycast group decrement
300  */
301 int __ipv6_dev_ac_dec(struct inet6_dev *idev, const struct in6_addr *addr)
302 {
303 	struct ifacaddr6 *aca, *prev_aca;
304 
305 	write_lock_bh(&idev->lock);
306 	prev_aca = NULL;
307 	for (aca = idev->ac_list; aca; aca = aca->aca_next) {
308 		if (ipv6_addr_equal(&aca->aca_addr, addr))
309 			break;
310 		prev_aca = aca;
311 	}
312 	if (!aca) {
313 		write_unlock_bh(&idev->lock);
314 		return -ENOENT;
315 	}
316 	if (--aca->aca_users > 0) {
317 		write_unlock_bh(&idev->lock);
318 		return 0;
319 	}
320 	if (prev_aca)
321 		prev_aca->aca_next = aca->aca_next;
322 	else
323 		idev->ac_list = aca->aca_next;
324 	write_unlock_bh(&idev->lock);
325 	addrconf_leave_solict(idev, &aca->aca_addr);
326 
327 	dst_hold(&aca->aca_rt->dst);
328 	ip6_del_rt(aca->aca_rt);
329 
330 	aca_put(aca);
331 	return 0;
332 }
333 
334 /* called with rcu_read_lock() */
335 static int ipv6_dev_ac_dec(struct net_device *dev, const struct in6_addr *addr)
336 {
337 	struct inet6_dev *idev = __in6_dev_get(dev);
338 
339 	if (idev == NULL)
340 		return -ENODEV;
341 	return __ipv6_dev_ac_dec(idev, addr);
342 }
343 
344 /*
345  *	check if the interface has this anycast address
346  *	called with rcu_read_lock()
347  */
348 static bool ipv6_chk_acast_dev(struct net_device *dev, const struct in6_addr *addr)
349 {
350 	struct inet6_dev *idev;
351 	struct ifacaddr6 *aca;
352 
353 	idev = __in6_dev_get(dev);
354 	if (idev) {
355 		read_lock_bh(&idev->lock);
356 		for (aca = idev->ac_list; aca; aca = aca->aca_next)
357 			if (ipv6_addr_equal(&aca->aca_addr, addr))
358 				break;
359 		read_unlock_bh(&idev->lock);
360 		return aca != NULL;
361 	}
362 	return false;
363 }
364 
365 /*
366  *	check if given interface (or any, if dev==0) has this anycast address
367  */
368 bool ipv6_chk_acast_addr(struct net *net, struct net_device *dev,
369 			 const struct in6_addr *addr)
370 {
371 	bool found = false;
372 
373 	rcu_read_lock();
374 	if (dev)
375 		found = ipv6_chk_acast_dev(dev, addr);
376 	else
377 		for_each_netdev_rcu(net, dev)
378 			if (ipv6_chk_acast_dev(dev, addr)) {
379 				found = true;
380 				break;
381 			}
382 	rcu_read_unlock();
383 	return found;
384 }
385 
386 /*	check if this anycast address is link-local on given interface or
387  *	is global
388  */
389 bool ipv6_chk_acast_addr_src(struct net *net, struct net_device *dev,
390 			     const struct in6_addr *addr)
391 {
392 	return ipv6_chk_acast_addr(net,
393 				   (ipv6_addr_type(addr) & IPV6_ADDR_LINKLOCAL ?
394 				    dev : NULL),
395 				   addr);
396 }
397 
398 #ifdef CONFIG_PROC_FS
399 struct ac6_iter_state {
400 	struct seq_net_private p;
401 	struct net_device *dev;
402 	struct inet6_dev *idev;
403 };
404 
405 #define ac6_seq_private(seq)	((struct ac6_iter_state *)(seq)->private)
406 
407 static inline struct ifacaddr6 *ac6_get_first(struct seq_file *seq)
408 {
409 	struct ifacaddr6 *im = NULL;
410 	struct ac6_iter_state *state = ac6_seq_private(seq);
411 	struct net *net = seq_file_net(seq);
412 
413 	state->idev = NULL;
414 	for_each_netdev_rcu(net, state->dev) {
415 		struct inet6_dev *idev;
416 		idev = __in6_dev_get(state->dev);
417 		if (!idev)
418 			continue;
419 		read_lock_bh(&idev->lock);
420 		im = idev->ac_list;
421 		if (im) {
422 			state->idev = idev;
423 			break;
424 		}
425 		read_unlock_bh(&idev->lock);
426 	}
427 	return im;
428 }
429 
430 static struct ifacaddr6 *ac6_get_next(struct seq_file *seq, struct ifacaddr6 *im)
431 {
432 	struct ac6_iter_state *state = ac6_seq_private(seq);
433 
434 	im = im->aca_next;
435 	while (!im) {
436 		if (likely(state->idev != NULL))
437 			read_unlock_bh(&state->idev->lock);
438 
439 		state->dev = next_net_device_rcu(state->dev);
440 		if (!state->dev) {
441 			state->idev = NULL;
442 			break;
443 		}
444 		state->idev = __in6_dev_get(state->dev);
445 		if (!state->idev)
446 			continue;
447 		read_lock_bh(&state->idev->lock);
448 		im = state->idev->ac_list;
449 	}
450 	return im;
451 }
452 
453 static struct ifacaddr6 *ac6_get_idx(struct seq_file *seq, loff_t pos)
454 {
455 	struct ifacaddr6 *im = ac6_get_first(seq);
456 	if (im)
457 		while (pos && (im = ac6_get_next(seq, im)) != NULL)
458 			--pos;
459 	return pos ? NULL : im;
460 }
461 
462 static void *ac6_seq_start(struct seq_file *seq, loff_t *pos)
463 	__acquires(RCU)
464 {
465 	rcu_read_lock();
466 	return ac6_get_idx(seq, *pos);
467 }
468 
469 static void *ac6_seq_next(struct seq_file *seq, void *v, loff_t *pos)
470 {
471 	struct ifacaddr6 *im = ac6_get_next(seq, v);
472 
473 	++*pos;
474 	return im;
475 }
476 
477 static void ac6_seq_stop(struct seq_file *seq, void *v)
478 	__releases(RCU)
479 {
480 	struct ac6_iter_state *state = ac6_seq_private(seq);
481 
482 	if (likely(state->idev != NULL)) {
483 		read_unlock_bh(&state->idev->lock);
484 		state->idev = NULL;
485 	}
486 	rcu_read_unlock();
487 }
488 
489 static int ac6_seq_show(struct seq_file *seq, void *v)
490 {
491 	struct ifacaddr6 *im = (struct ifacaddr6 *)v;
492 	struct ac6_iter_state *state = ac6_seq_private(seq);
493 
494 	seq_printf(seq, "%-4d %-15s %pi6 %5d\n",
495 		   state->dev->ifindex, state->dev->name,
496 		   &im->aca_addr, im->aca_users);
497 	return 0;
498 }
499 
500 static const struct seq_operations ac6_seq_ops = {
501 	.start	=	ac6_seq_start,
502 	.next	=	ac6_seq_next,
503 	.stop	=	ac6_seq_stop,
504 	.show	=	ac6_seq_show,
505 };
506 
507 static int ac6_seq_open(struct inode *inode, struct file *file)
508 {
509 	return seq_open_net(inode, file, &ac6_seq_ops,
510 			    sizeof(struct ac6_iter_state));
511 }
512 
513 static const struct file_operations ac6_seq_fops = {
514 	.owner		=	THIS_MODULE,
515 	.open		=	ac6_seq_open,
516 	.read		=	seq_read,
517 	.llseek		=	seq_lseek,
518 	.release	=	seq_release_net,
519 };
520 
521 int __net_init ac6_proc_init(struct net *net)
522 {
523 	if (!proc_create("anycast6", S_IRUGO, net->proc_net, &ac6_seq_fops))
524 		return -ENOMEM;
525 
526 	return 0;
527 }
528 
529 void ac6_proc_exit(struct net *net)
530 {
531 	remove_proc_entry("anycast6", net->proc_net);
532 }
533 #endif
534 
535