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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         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 

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