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TOMOYO Linux Cross Reference
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 /*
 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         if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
 64                 return -EPERM;
 65         if (ipv6_addr_is_multicast(addr))
 66                 return -EINVAL;
 67         if (ipv6_chk_addr(net, addr, NULL, 0))
 68                 return -EINVAL;
 69 
 70         pac = sock_kmalloc(sk, sizeof(struct ipv6_ac_socklist), GFP_KERNEL);
 71         if (pac == NULL)
 72                 return -ENOMEM;
 73         pac->acl_next = NULL;
 74         pac->acl_addr = *addr;
 75 
 76         rtnl_lock();
 77         if (ifindex == 0) {
 78                 struct rt6_info *rt;
 79 
 80                 rt = rt6_lookup(net, addr, NULL, 0, 0);
 81                 if (rt) {
 82                         dev = rt->dst.dev;
 83                         ip6_rt_put(rt);
 84                 } else if (ishost) {
 85                         err = -EADDRNOTAVAIL;
 86                         goto error;
 87                 } else {
 88                         /* router, no matching interface: just pick one */
 89                         dev = __dev_get_by_flags(net, IFF_UP,
 90                                                  IFF_UP | IFF_LOOPBACK);
 91                 }
 92         } else
 93                 dev = __dev_get_by_index(net, ifindex);
 94 
 95         if (dev == NULL) {
 96                 err = -ENODEV;
 97                 goto error;
 98         }
 99 
100         idev = __in6_dev_get(dev);
101         if (!idev) {
102                 if (ifindex)
103                         err = -ENODEV;
104                 else
105                         err = -EADDRNOTAVAIL;
106                 goto error;
107         }
108         /* reset ishost, now that we have a specific device */
109         ishost = !idev->cnf.forwarding;
110 
111         pac->acl_ifindex = dev->ifindex;
112 
113         /* XXX
114          * For hosts, allow link-local or matching prefix anycasts.
115          * This obviates the need for propagating anycast routes while
116          * still allowing some non-router anycast participation.
117          */
118         if (!ipv6_chk_prefix(addr, dev)) {
119                 if (ishost)
120                         err = -EADDRNOTAVAIL;
121                 if (err)
122                         goto error;
123         }
124 
125         err = __ipv6_dev_ac_inc(idev, addr);
126         if (!err) {
127                 pac->acl_next = np->ipv6_ac_list;
128                 np->ipv6_ac_list = pac;
129                 pac = NULL;
130         }
131 
132 error:
133         rtnl_unlock();
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         rtnl_lock();
150         prev_pac = NULL;
151         for (pac = np->ipv6_ac_list; pac; pac = pac->acl_next) {
152                 if ((ifindex == 0 || pac->acl_ifindex == ifindex) &&
153                      ipv6_addr_equal(&pac->acl_addr, addr))
154                         break;
155                 prev_pac = pac;
156         }
157         if (!pac) {
158                 rtnl_unlock();
159                 return -ENOENT;
160         }
161         if (prev_pac)
162                 prev_pac->acl_next = pac->acl_next;
163         else
164                 np->ipv6_ac_list = pac->acl_next;
165 
166         dev = __dev_get_by_index(net, pac->acl_ifindex);
167         if (dev)
168                 ipv6_dev_ac_dec(dev, &pac->acl_addr);
169         rtnl_unlock();
170 
171         sock_kfree_s(sk, pac, sizeof(*pac));
172         return 0;
173 }
174 
175 void ipv6_sock_ac_close(struct sock *sk)
176 {
177         struct ipv6_pinfo *np = inet6_sk(sk);
178         struct net_device *dev = NULL;
179         struct ipv6_ac_socklist *pac;
180         struct net *net = sock_net(sk);
181         int     prev_index;
182 
183         if (!np->ipv6_ac_list)
184                 return;
185 
186         rtnl_lock();
187         pac = np->ipv6_ac_list;
188         np->ipv6_ac_list = NULL;
189 
190         prev_index = 0;
191         while (pac) {
192                 struct ipv6_ac_socklist *next = pac->acl_next;
193 
194                 if (pac->acl_ifindex != prev_index) {
195                         dev = __dev_get_by_index(net, pac->acl_ifindex);
196                         prev_index = pac->acl_ifindex;
197                 }
198                 if (dev)
199                         ipv6_dev_ac_dec(dev, &pac->acl_addr);
200                 sock_kfree_s(sk, pac, sizeof(*pac));
201                 pac = next;
202         }
203         rtnl_unlock();
204 }
205 
206 static void aca_get(struct ifacaddr6 *aca)
207 {
208         atomic_inc(&aca->aca_refcnt);
209 }
210 
211 static void aca_put(struct ifacaddr6 *ac)
212 {
213         if (atomic_dec_and_test(&ac->aca_refcnt)) {
214                 in6_dev_put(ac->aca_idev);
215                 dst_release(&ac->aca_rt->dst);
216                 kfree(ac);
217         }
218 }
219 
220 static struct ifacaddr6 *aca_alloc(struct rt6_info *rt,
221                                    const struct in6_addr *addr)
222 {
223         struct inet6_dev *idev = rt->rt6i_idev;
224         struct ifacaddr6 *aca;
225 
226         aca = kzalloc(sizeof(*aca), GFP_ATOMIC);
227         if (aca == NULL)
228                 return NULL;
229 
230         aca->aca_addr = *addr;
231         in6_dev_hold(idev);
232         aca->aca_idev = idev;
233         aca->aca_rt = rt;
234         aca->aca_users = 1;
235         /* aca_tstamp should be updated upon changes */
236         aca->aca_cstamp = aca->aca_tstamp = jiffies;
237         atomic_set(&aca->aca_refcnt, 1);
238 
239         return aca;
240 }
241 
242 /*
243  *      device anycast group inc (add if not found)
244  */
245 int __ipv6_dev_ac_inc(struct inet6_dev *idev, const struct in6_addr *addr)
246 {
247         struct ifacaddr6 *aca;
248         struct rt6_info *rt;
249         int err;
250 
251         ASSERT_RTNL();
252 
253         write_lock_bh(&idev->lock);
254         if (idev->dead) {
255                 err = -ENODEV;
256                 goto out;
257         }
258 
259         for (aca = idev->ac_list; aca; aca = aca->aca_next) {
260                 if (ipv6_addr_equal(&aca->aca_addr, addr)) {
261                         aca->aca_users++;
262                         err = 0;
263                         goto out;
264                 }
265         }
266 
267         rt = addrconf_dst_alloc(idev, addr, true);
268         if (IS_ERR(rt)) {
269                 err = PTR_ERR(rt);
270                 goto out;
271         }
272         aca = aca_alloc(rt, addr);
273         if (aca == NULL) {
274                 ip6_rt_put(rt);
275                 err = -ENOMEM;
276                 goto out;
277         }
278 
279         aca->aca_next = idev->ac_list;
280         idev->ac_list = aca;
281 
282         /* Hold this for addrconf_join_solict() below before we unlock,
283          * it is already exposed via idev->ac_list.
284          */
285         aca_get(aca);
286         write_unlock_bh(&idev->lock);
287 
288         ip6_ins_rt(rt);
289 
290         addrconf_join_solict(idev->dev, &aca->aca_addr);
291 
292         aca_put(aca);
293         return 0;
294 out:
295         write_unlock_bh(&idev->lock);
296         return err;
297 }
298 
299 /*
300  *      device anycast group decrement
301  */
302 int __ipv6_dev_ac_dec(struct inet6_dev *idev, const struct in6_addr *addr)
303 {
304         struct ifacaddr6 *aca, *prev_aca;
305 
306         ASSERT_RTNL();
307 
308         write_lock_bh(&idev->lock);
309         prev_aca = NULL;
310         for (aca = idev->ac_list; aca; aca = aca->aca_next) {
311                 if (ipv6_addr_equal(&aca->aca_addr, addr))
312                         break;
313                 prev_aca = aca;
314         }
315         if (!aca) {
316                 write_unlock_bh(&idev->lock);
317                 return -ENOENT;
318         }
319         if (--aca->aca_users > 0) {
320                 write_unlock_bh(&idev->lock);
321                 return 0;
322         }
323         if (prev_aca)
324                 prev_aca->aca_next = aca->aca_next;
325         else
326                 idev->ac_list = aca->aca_next;
327         write_unlock_bh(&idev->lock);
328         addrconf_leave_solict(idev, &aca->aca_addr);
329 
330         dst_hold(&aca->aca_rt->dst);
331         ip6_del_rt(aca->aca_rt);
332 
333         aca_put(aca);
334         return 0;
335 }
336 
337 /* called with rtnl_lock() */
338 static int ipv6_dev_ac_dec(struct net_device *dev, const struct in6_addr *addr)
339 {
340         struct inet6_dev *idev = __in6_dev_get(dev);
341 
342         if (idev == NULL)
343                 return -ENODEV;
344         return __ipv6_dev_ac_dec(idev, addr);
345 }
346 
347 void ipv6_ac_destroy_dev(struct inet6_dev *idev)
348 {
349         struct ifacaddr6 *aca;
350 
351         write_lock_bh(&idev->lock);
352         while ((aca = idev->ac_list) != NULL) {
353                 idev->ac_list = aca->aca_next;
354                 write_unlock_bh(&idev->lock);
355 
356                 addrconf_leave_solict(idev, &aca->aca_addr);
357 
358                 dst_hold(&aca->aca_rt->dst);
359                 ip6_del_rt(aca->aca_rt);
360 
361                 aca_put(aca);
362 
363                 write_lock_bh(&idev->lock);
364         }
365         write_unlock_bh(&idev->lock);
366 }
367 
368 /*
369  *      check if the interface has this anycast address
370  *      called with rcu_read_lock()
371  */
372 static bool ipv6_chk_acast_dev(struct net_device *dev, const struct in6_addr *addr)
373 {
374         struct inet6_dev *idev;
375         struct ifacaddr6 *aca;
376 
377         idev = __in6_dev_get(dev);
378         if (idev) {
379                 read_lock_bh(&idev->lock);
380                 for (aca = idev->ac_list; aca; aca = aca->aca_next)
381                         if (ipv6_addr_equal(&aca->aca_addr, addr))
382                                 break;
383                 read_unlock_bh(&idev->lock);
384                 return aca != NULL;
385         }
386         return false;
387 }
388 
389 /*
390  *      check if given interface (or any, if dev==0) has this anycast address
391  */
392 bool ipv6_chk_acast_addr(struct net *net, struct net_device *dev,
393                          const struct in6_addr *addr)
394 {
395         bool found = false;
396 
397         rcu_read_lock();
398         if (dev)
399                 found = ipv6_chk_acast_dev(dev, addr);
400         else
401                 for_each_netdev_rcu(net, dev)
402                         if (ipv6_chk_acast_dev(dev, addr)) {
403                                 found = true;
404                                 break;
405                         }
406         rcu_read_unlock();
407         return found;
408 }
409 
410 /*      check if this anycast address is link-local on given interface or
411  *      is global
412  */
413 bool ipv6_chk_acast_addr_src(struct net *net, struct net_device *dev,
414                              const struct in6_addr *addr)
415 {
416         return ipv6_chk_acast_addr(net,
417                                    (ipv6_addr_type(addr) & IPV6_ADDR_LINKLOCAL ?
418                                     dev : NULL),
419                                    addr);
420 }
421 
422 #ifdef CONFIG_PROC_FS
423 struct ac6_iter_state {
424         struct seq_net_private p;
425         struct net_device *dev;
426         struct inet6_dev *idev;
427 };
428 
429 #define ac6_seq_private(seq)    ((struct ac6_iter_state *)(seq)->private)
430 
431 static inline struct ifacaddr6 *ac6_get_first(struct seq_file *seq)
432 {
433         struct ifacaddr6 *im = NULL;
434         struct ac6_iter_state *state = ac6_seq_private(seq);
435         struct net *net = seq_file_net(seq);
436 
437         state->idev = NULL;
438         for_each_netdev_rcu(net, state->dev) {
439                 struct inet6_dev *idev;
440                 idev = __in6_dev_get(state->dev);
441                 if (!idev)
442                         continue;
443                 read_lock_bh(&idev->lock);
444                 im = idev->ac_list;
445                 if (im) {
446                         state->idev = idev;
447                         break;
448                 }
449                 read_unlock_bh(&idev->lock);
450         }
451         return im;
452 }
453 
454 static struct ifacaddr6 *ac6_get_next(struct seq_file *seq, struct ifacaddr6 *im)
455 {
456         struct ac6_iter_state *state = ac6_seq_private(seq);
457 
458         im = im->aca_next;
459         while (!im) {
460                 if (likely(state->idev != NULL))
461                         read_unlock_bh(&state->idev->lock);
462 
463                 state->dev = next_net_device_rcu(state->dev);
464                 if (!state->dev) {
465                         state->idev = NULL;
466                         break;
467                 }
468                 state->idev = __in6_dev_get(state->dev);
469                 if (!state->idev)
470                         continue;
471                 read_lock_bh(&state->idev->lock);
472                 im = state->idev->ac_list;
473         }
474         return im;
475 }
476 
477 static struct ifacaddr6 *ac6_get_idx(struct seq_file *seq, loff_t pos)
478 {
479         struct ifacaddr6 *im = ac6_get_first(seq);
480         if (im)
481                 while (pos && (im = ac6_get_next(seq, im)) != NULL)
482                         --pos;
483         return pos ? NULL : im;
484 }
485 
486 static void *ac6_seq_start(struct seq_file *seq, loff_t *pos)
487         __acquires(RCU)
488 {
489         rcu_read_lock();
490         return ac6_get_idx(seq, *pos);
491 }
492 
493 static void *ac6_seq_next(struct seq_file *seq, void *v, loff_t *pos)
494 {
495         struct ifacaddr6 *im = ac6_get_next(seq, v);
496 
497         ++*pos;
498         return im;
499 }
500 
501 static void ac6_seq_stop(struct seq_file *seq, void *v)
502         __releases(RCU)
503 {
504         struct ac6_iter_state *state = ac6_seq_private(seq);
505 
506         if (likely(state->idev != NULL)) {
507                 read_unlock_bh(&state->idev->lock);
508                 state->idev = NULL;
509         }
510         rcu_read_unlock();
511 }
512 
513 static int ac6_seq_show(struct seq_file *seq, void *v)
514 {
515         struct ifacaddr6 *im = (struct ifacaddr6 *)v;
516         struct ac6_iter_state *state = ac6_seq_private(seq);
517 
518         seq_printf(seq, "%-4d %-15s %pi6 %5d\n",
519                    state->dev->ifindex, state->dev->name,
520                    &im->aca_addr, im->aca_users);
521         return 0;
522 }
523 
524 static const struct seq_operations ac6_seq_ops = {
525         .start  =       ac6_seq_start,
526         .next   =       ac6_seq_next,
527         .stop   =       ac6_seq_stop,
528         .show   =       ac6_seq_show,
529 };
530 
531 static int ac6_seq_open(struct inode *inode, struct file *file)
532 {
533         return seq_open_net(inode, file, &ac6_seq_ops,
534                             sizeof(struct ac6_iter_state));
535 }
536 
537 static const struct file_operations ac6_seq_fops = {
538         .owner          =       THIS_MODULE,
539         .open           =       ac6_seq_open,
540         .read           =       seq_read,
541         .llseek         =       seq_lseek,
542         .release        =       seq_release_net,
543 };
544 
545 int __net_init ac6_proc_init(struct net *net)
546 {
547         if (!proc_create("anycast6", S_IRUGO, net->proc_net, &ac6_seq_fops))
548                 return -ENOMEM;
549 
550         return 0;
551 }
552 
553 void ac6_proc_exit(struct net *net)
554 {
555         remove_proc_entry("anycast6", net->proc_net);
556 }
557 #endif
558 
559 

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