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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_RWLOCK(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                 write_lock_bh(&ipv6_sk_ac_lock);
132                 pac->acl_next = np->ipv6_ac_list;
133                 np->ipv6_ac_list = pac;
134                 write_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         write_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                 write_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         write_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         write_lock_bh(&ipv6_sk_ac_lock);
196         pac = np->ipv6_ac_list;
197         np->ipv6_ac_list = NULL;
198         write_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 
387 #ifdef CONFIG_PROC_FS
388 struct ac6_iter_state {
389         struct seq_net_private p;
390         struct net_device *dev;
391         struct inet6_dev *idev;
392 };
393 
394 #define ac6_seq_private(seq)    ((struct ac6_iter_state *)(seq)->private)
395 
396 static inline struct ifacaddr6 *ac6_get_first(struct seq_file *seq)
397 {
398         struct ifacaddr6 *im = NULL;
399         struct ac6_iter_state *state = ac6_seq_private(seq);
400         struct net *net = seq_file_net(seq);
401 
402         state->idev = NULL;
403         for_each_netdev_rcu(net, state->dev) {
404                 struct inet6_dev *idev;
405                 idev = __in6_dev_get(state->dev);
406                 if (!idev)
407                         continue;
408                 read_lock_bh(&idev->lock);
409                 im = idev->ac_list;
410                 if (im) {
411                         state->idev = idev;
412                         break;
413                 }
414                 read_unlock_bh(&idev->lock);
415         }
416         return im;
417 }
418 
419 static struct ifacaddr6 *ac6_get_next(struct seq_file *seq, struct ifacaddr6 *im)
420 {
421         struct ac6_iter_state *state = ac6_seq_private(seq);
422 
423         im = im->aca_next;
424         while (!im) {
425                 if (likely(state->idev != NULL))
426                         read_unlock_bh(&state->idev->lock);
427 
428                 state->dev = next_net_device_rcu(state->dev);
429                 if (!state->dev) {
430                         state->idev = NULL;
431                         break;
432                 }
433                 state->idev = __in6_dev_get(state->dev);
434                 if (!state->idev)
435                         continue;
436                 read_lock_bh(&state->idev->lock);
437                 im = state->idev->ac_list;
438         }
439         return im;
440 }
441 
442 static struct ifacaddr6 *ac6_get_idx(struct seq_file *seq, loff_t pos)
443 {
444         struct ifacaddr6 *im = ac6_get_first(seq);
445         if (im)
446                 while (pos && (im = ac6_get_next(seq, im)) != NULL)
447                         --pos;
448         return pos ? NULL : im;
449 }
450 
451 static void *ac6_seq_start(struct seq_file *seq, loff_t *pos)
452         __acquires(RCU)
453 {
454         rcu_read_lock();
455         return ac6_get_idx(seq, *pos);
456 }
457 
458 static void *ac6_seq_next(struct seq_file *seq, void *v, loff_t *pos)
459 {
460         struct ifacaddr6 *im = ac6_get_next(seq, v);
461 
462         ++*pos;
463         return im;
464 }
465 
466 static void ac6_seq_stop(struct seq_file *seq, void *v)
467         __releases(RCU)
468 {
469         struct ac6_iter_state *state = ac6_seq_private(seq);
470 
471         if (likely(state->idev != NULL)) {
472                 read_unlock_bh(&state->idev->lock);
473                 state->idev = NULL;
474         }
475         rcu_read_unlock();
476 }
477 
478 static int ac6_seq_show(struct seq_file *seq, void *v)
479 {
480         struct ifacaddr6 *im = (struct ifacaddr6 *)v;
481         struct ac6_iter_state *state = ac6_seq_private(seq);
482 
483         seq_printf(seq, "%-4d %-15s %pi6 %5d\n",
484                    state->dev->ifindex, state->dev->name,
485                    &im->aca_addr, im->aca_users);
486         return 0;
487 }
488 
489 static const struct seq_operations ac6_seq_ops = {
490         .start  =       ac6_seq_start,
491         .next   =       ac6_seq_next,
492         .stop   =       ac6_seq_stop,
493         .show   =       ac6_seq_show,
494 };
495 
496 static int ac6_seq_open(struct inode *inode, struct file *file)
497 {
498         return seq_open_net(inode, file, &ac6_seq_ops,
499                             sizeof(struct ac6_iter_state));
500 }
501 
502 static const struct file_operations ac6_seq_fops = {
503         .owner          =       THIS_MODULE,
504         .open           =       ac6_seq_open,
505         .read           =       seq_read,
506         .llseek         =       seq_lseek,
507         .release        =       seq_release_net,
508 };
509 
510 int __net_init ac6_proc_init(struct net *net)
511 {
512         if (!proc_net_fops_create(net, "anycast6", S_IRUGO, &ac6_seq_fops))
513                 return -ENOMEM;
514 
515         return 0;
516 }
517 
518 void ac6_proc_exit(struct net *net)
519 {
520         proc_net_remove(net, "anycast6");
521 }
522 #endif
523 
524 

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