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Linux/net/ipv6/anycast.c

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  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         rtnl_lock();
 81         rcu_read_lock();
 82         if (ifindex == 0) {
 83                 struct rt6_info *rt;
 84 
 85                 rt = rt6_lookup(net, addr, NULL, 0, 0);
 86                 if (rt) {
 87                         dev = rt->dst.dev;
 88                         ip6_rt_put(rt);
 89                 } else if (ishost) {
 90                         err = -EADDRNOTAVAIL;
 91                         goto error;
 92                 } else {
 93                         /* router, no matching interface: just pick one */
 94                         dev = dev_get_by_flags_rcu(net, IFF_UP,
 95                                                    IFF_UP | IFF_LOOPBACK);
 96                 }
 97         } else
 98                 dev = dev_get_by_index_rcu(net, ifindex);
 99 
100         if (dev == NULL) {
101                 err = -ENODEV;
102                 goto error;
103         }
104 
105         idev = __in6_dev_get(dev);
106         if (!idev) {
107                 if (ifindex)
108                         err = -ENODEV;
109                 else
110                         err = -EADDRNOTAVAIL;
111                 goto error;
112         }
113         /* reset ishost, now that we have a specific device */
114         ishost = !idev->cnf.forwarding;
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 error;
128         }
129 
130         err = ipv6_dev_ac_inc(dev, addr);
131         if (!err) {
132                 spin_lock_bh(&ipv6_sk_ac_lock);
133                 pac->acl_next = np->ipv6_ac_list;
134                 np->ipv6_ac_list = pac;
135                 spin_unlock_bh(&ipv6_sk_ac_lock);
136                 pac = NULL;
137         }
138 
139 error:
140         rcu_read_unlock();
141         rtnl_unlock();
142         if (pac)
143                 sock_kfree_s(sk, pac, sizeof(*pac));
144         return err;
145 }
146 
147 /*
148  *      socket leave an anycast group
149  */
150 int ipv6_sock_ac_drop(struct sock *sk, int ifindex, const struct in6_addr *addr)
151 {
152         struct ipv6_pinfo *np = inet6_sk(sk);
153         struct net_device *dev;
154         struct ipv6_ac_socklist *pac, *prev_pac;
155         struct net *net = sock_net(sk);
156 
157         spin_lock_bh(&ipv6_sk_ac_lock);
158         prev_pac = NULL;
159         for (pac = np->ipv6_ac_list; pac; pac = pac->acl_next) {
160                 if ((ifindex == 0 || pac->acl_ifindex == ifindex) &&
161                      ipv6_addr_equal(&pac->acl_addr, addr))
162                         break;
163                 prev_pac = pac;
164         }
165         if (!pac) {
166                 spin_unlock_bh(&ipv6_sk_ac_lock);
167                 return -ENOENT;
168         }
169         if (prev_pac)
170                 prev_pac->acl_next = pac->acl_next;
171         else
172                 np->ipv6_ac_list = pac->acl_next;
173 
174         spin_unlock_bh(&ipv6_sk_ac_lock);
175 
176         rtnl_lock();
177         rcu_read_lock();
178         dev = dev_get_by_index_rcu(net, pac->acl_ifindex);
179         if (dev)
180                 ipv6_dev_ac_dec(dev, &pac->acl_addr);
181         rcu_read_unlock();
182         rtnl_unlock();
183 
184         sock_kfree_s(sk, pac, sizeof(*pac));
185         if (!dev)
186                 return -ENODEV;
187         return 0;
188 }
189 
190 void ipv6_sock_ac_close(struct sock *sk)
191 {
192         struct ipv6_pinfo *np = inet6_sk(sk);
193         struct net_device *dev = NULL;
194         struct ipv6_ac_socklist *pac;
195         struct net *net = sock_net(sk);
196         int     prev_index;
197 
198         if (!np->ipv6_ac_list)
199                 return;
200 
201         spin_lock_bh(&ipv6_sk_ac_lock);
202         pac = np->ipv6_ac_list;
203         np->ipv6_ac_list = NULL;
204         spin_unlock_bh(&ipv6_sk_ac_lock);
205 
206         prev_index = 0;
207         rtnl_lock();
208         rcu_read_lock();
209         while (pac) {
210                 struct ipv6_ac_socklist *next = pac->acl_next;
211 
212                 if (pac->acl_ifindex != prev_index) {
213                         dev = dev_get_by_index_rcu(net, pac->acl_ifindex);
214                         prev_index = pac->acl_ifindex;
215                 }
216                 if (dev)
217                         ipv6_dev_ac_dec(dev, &pac->acl_addr);
218                 sock_kfree_s(sk, pac, sizeof(*pac));
219                 pac = next;
220         }
221         rcu_read_unlock();
222         rtnl_unlock();
223 }
224 
225 static void aca_put(struct ifacaddr6 *ac)
226 {
227         if (atomic_dec_and_test(&ac->aca_refcnt)) {
228                 in6_dev_put(ac->aca_idev);
229                 dst_release(&ac->aca_rt->dst);
230                 kfree(ac);
231         }
232 }
233 
234 /*
235  *      device anycast group inc (add if not found)
236  */
237 int ipv6_dev_ac_inc(struct net_device *dev, const struct in6_addr *addr)
238 {
239         struct ifacaddr6 *aca;
240         struct inet6_dev *idev;
241         struct rt6_info *rt;
242         int err;
243 
244         ASSERT_RTNL();
245 
246         idev = in6_dev_get(dev);
247 
248         if (idev == NULL)
249                 return -EINVAL;
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         /*
266          *      not found: create a new one.
267          */
268 
269         aca = kzalloc(sizeof(struct ifacaddr6), GFP_ATOMIC);
270 
271         if (aca == NULL) {
272                 err = -ENOMEM;
273                 goto out;
274         }
275 
276         rt = addrconf_dst_alloc(idev, addr, true);
277         if (IS_ERR(rt)) {
278                 kfree(aca);
279                 err = PTR_ERR(rt);
280                 goto out;
281         }
282 
283         aca->aca_addr = *addr;
284         aca->aca_idev = idev;
285         aca->aca_rt = rt;
286         aca->aca_users = 1;
287         /* aca_tstamp should be updated upon changes */
288         aca->aca_cstamp = aca->aca_tstamp = jiffies;
289         atomic_set(&aca->aca_refcnt, 2);
290         spin_lock_init(&aca->aca_lock);
291 
292         aca->aca_next = idev->ac_list;
293         idev->ac_list = aca;
294         write_unlock_bh(&idev->lock);
295 
296         ip6_ins_rt(rt);
297 
298         addrconf_join_solict(dev, &aca->aca_addr);
299 
300         aca_put(aca);
301         return 0;
302 out:
303         write_unlock_bh(&idev->lock);
304         in6_dev_put(idev);
305         return err;
306 }
307 
308 /*
309  *      device anycast group decrement
310  */
311 int __ipv6_dev_ac_dec(struct inet6_dev *idev, const struct in6_addr *addr)
312 {
313         struct ifacaddr6 *aca, *prev_aca;
314 
315         ASSERT_RTNL();
316 
317         write_lock_bh(&idev->lock);
318         prev_aca = NULL;
319         for (aca = idev->ac_list; aca; aca = aca->aca_next) {
320                 if (ipv6_addr_equal(&aca->aca_addr, addr))
321                         break;
322                 prev_aca = aca;
323         }
324         if (!aca) {
325                 write_unlock_bh(&idev->lock);
326                 return -ENOENT;
327         }
328         if (--aca->aca_users > 0) {
329                 write_unlock_bh(&idev->lock);
330                 return 0;
331         }
332         if (prev_aca)
333                 prev_aca->aca_next = aca->aca_next;
334         else
335                 idev->ac_list = aca->aca_next;
336         write_unlock_bh(&idev->lock);
337         addrconf_leave_solict(idev, &aca->aca_addr);
338 
339         dst_hold(&aca->aca_rt->dst);
340         ip6_del_rt(aca->aca_rt);
341 
342         aca_put(aca);
343         return 0;
344 }
345 
346 /* called with rcu_read_lock() */
347 static int ipv6_dev_ac_dec(struct net_device *dev, const struct in6_addr *addr)
348 {
349         struct inet6_dev *idev = __in6_dev_get(dev);
350 
351         if (idev == NULL)
352                 return -ENODEV;
353         return __ipv6_dev_ac_dec(idev, addr);
354 }
355 
356 /*
357  *      check if the interface has this anycast address
358  *      called with rcu_read_lock()
359  */
360 static bool ipv6_chk_acast_dev(struct net_device *dev, const struct in6_addr *addr)
361 {
362         struct inet6_dev *idev;
363         struct ifacaddr6 *aca;
364 
365         idev = __in6_dev_get(dev);
366         if (idev) {
367                 read_lock_bh(&idev->lock);
368                 for (aca = idev->ac_list; aca; aca = aca->aca_next)
369                         if (ipv6_addr_equal(&aca->aca_addr, addr))
370                                 break;
371                 read_unlock_bh(&idev->lock);
372                 return aca != NULL;
373         }
374         return false;
375 }
376 
377 /*
378  *      check if given interface (or any, if dev==0) has this anycast address
379  */
380 bool ipv6_chk_acast_addr(struct net *net, struct net_device *dev,
381                          const struct in6_addr *addr)
382 {
383         bool found = false;
384 
385         rcu_read_lock();
386         if (dev)
387                 found = ipv6_chk_acast_dev(dev, addr);
388         else
389                 for_each_netdev_rcu(net, dev)
390                         if (ipv6_chk_acast_dev(dev, addr)) {
391                                 found = true;
392                                 break;
393                         }
394         rcu_read_unlock();
395         return found;
396 }
397 
398 
399 #ifdef CONFIG_PROC_FS
400 struct ac6_iter_state {
401         struct seq_net_private p;
402         struct net_device *dev;
403         struct inet6_dev *idev;
404 };
405 
406 #define ac6_seq_private(seq)    ((struct ac6_iter_state *)(seq)->private)
407 
408 static inline struct ifacaddr6 *ac6_get_first(struct seq_file *seq)
409 {
410         struct ifacaddr6 *im = NULL;
411         struct ac6_iter_state *state = ac6_seq_private(seq);
412         struct net *net = seq_file_net(seq);
413 
414         state->idev = NULL;
415         for_each_netdev_rcu(net, state->dev) {
416                 struct inet6_dev *idev;
417                 idev = __in6_dev_get(state->dev);
418                 if (!idev)
419                         continue;
420                 read_lock_bh(&idev->lock);
421                 im = idev->ac_list;
422                 if (im) {
423                         state->idev = idev;
424                         break;
425                 }
426                 read_unlock_bh(&idev->lock);
427         }
428         return im;
429 }
430 
431 static struct ifacaddr6 *ac6_get_next(struct seq_file *seq, struct ifacaddr6 *im)
432 {
433         struct ac6_iter_state *state = ac6_seq_private(seq);
434 
435         im = im->aca_next;
436         while (!im) {
437                 if (likely(state->idev != NULL))
438                         read_unlock_bh(&state->idev->lock);
439 
440                 state->dev = next_net_device_rcu(state->dev);
441                 if (!state->dev) {
442                         state->idev = NULL;
443                         break;
444                 }
445                 state->idev = __in6_dev_get(state->dev);
446                 if (!state->idev)
447                         continue;
448                 read_lock_bh(&state->idev->lock);
449                 im = state->idev->ac_list;
450         }
451         return im;
452 }
453 
454 static struct ifacaddr6 *ac6_get_idx(struct seq_file *seq, loff_t pos)
455 {
456         struct ifacaddr6 *im = ac6_get_first(seq);
457         if (im)
458                 while (pos && (im = ac6_get_next(seq, im)) != NULL)
459                         --pos;
460         return pos ? NULL : im;
461 }
462 
463 static void *ac6_seq_start(struct seq_file *seq, loff_t *pos)
464         __acquires(RCU)
465 {
466         rcu_read_lock();
467         return ac6_get_idx(seq, *pos);
468 }
469 
470 static void *ac6_seq_next(struct seq_file *seq, void *v, loff_t *pos)
471 {
472         struct ifacaddr6 *im = ac6_get_next(seq, v);
473 
474         ++*pos;
475         return im;
476 }
477 
478 static void ac6_seq_stop(struct seq_file *seq, void *v)
479         __releases(RCU)
480 {
481         struct ac6_iter_state *state = ac6_seq_private(seq);
482 
483         if (likely(state->idev != NULL)) {
484                 read_unlock_bh(&state->idev->lock);
485                 state->idev = NULL;
486         }
487         rcu_read_unlock();
488 }
489 
490 static int ac6_seq_show(struct seq_file *seq, void *v)
491 {
492         struct ifacaddr6 *im = (struct ifacaddr6 *)v;
493         struct ac6_iter_state *state = ac6_seq_private(seq);
494 
495         seq_printf(seq, "%-4d %-15s %pi6 %5d\n",
496                    state->dev->ifindex, state->dev->name,
497                    &im->aca_addr, im->aca_users);
498         return 0;
499 }
500 
501 static const struct seq_operations ac6_seq_ops = {
502         .start  =       ac6_seq_start,
503         .next   =       ac6_seq_next,
504         .stop   =       ac6_seq_stop,
505         .show   =       ac6_seq_show,
506 };
507 
508 static int ac6_seq_open(struct inode *inode, struct file *file)
509 {
510         return seq_open_net(inode, file, &ac6_seq_ops,
511                             sizeof(struct ac6_iter_state));
512 }
513 
514 static const struct file_operations ac6_seq_fops = {
515         .owner          =       THIS_MODULE,
516         .open           =       ac6_seq_open,
517         .read           =       seq_read,
518         .llseek         =       seq_lseek,
519         .release        =       seq_release_net,
520 };
521 
522 int __net_init ac6_proc_init(struct net *net)
523 {
524         if (!proc_create("anycast6", S_IRUGO, net->proc_net, &ac6_seq_fops))
525                 return -ENOMEM;
526 
527         return 0;
528 }
529 
530 void ac6_proc_exit(struct net *net)
531 {
532         remove_proc_entry("anycast6", net->proc_net);
533 }
534 #endif
535 
536 

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