net/ipv6/anycast.c

   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
  33 #include <net/sock.h>
  34 #include <net/snmp.h>
  35
  36 #include <net/ipv6.h>
  37 #include <net/protocol.h>
  38 #include <net/if_inet6.h>
  39 #include <net/ndisc.h>
  40 #include <net/addrconf.h>
  41 #include <net/ip6_route.h>
  42
  43 #include <net/checksum.h>
  44
  45 static int ipv6_dev_ac_dec(struct net_device *dev, struct in6_addr *addr);
  46
  47 /* Big ac list lock for all the sockets */
  48 static DEFINE_RWLOCK(ipv6_sk_ac_lock);
  49
  50 static int
  51 ip6_onlink(struct in6_addr *addr, struct net_device *dev)
  52 {
  53         struct inet6_dev        *idev;
  54         struct inet6_ifaddr     *ifa;
  55         int     onlink;
  56
  57         onlink = 0;
  58         rcu_read_lock();
  59         idev = __in6_dev_get(dev);
  60         if (idev) {
  61                 read_lock_bh(&idev->lock);
  62                 for (ifa=idev->addr_list; ifa; ifa=ifa->if_next) {
  63                         onlink = ipv6_prefix_equal(addr, &ifa->addr,
  64                                                    ifa->prefix_len);
  65                         if (onlink)
  66                                 break;
  67                 }
  68                 read_unlock_bh(&idev->lock);
  69         }
  70         rcu_read_unlock();
  71         return onlink;
  72 }
  73
  74 /*
  75  *      socket join an anycast group
  76  */
  77
  78 int ipv6_sock_ac_join(struct sock *sk, int ifindex, struct in6_addr *addr)
  79 {
  80         struct ipv6_pinfo *np = inet6_sk(sk);
  81         struct net_device *dev = NULL;
  82         struct inet6_dev *idev;
  83         struct ipv6_ac_socklist *pac;
  84         int     ishost = !ipv6_devconf.forwarding;
  85         int     err = 0;
  86
  87         if (!capable(CAP_NET_ADMIN))
  88                 return -EPERM;
  89         if (ipv6_addr_is_multicast(addr))
  90                 return -EINVAL;
  91         if (ipv6_chk_addr(addr, NULL, 0))
  92                 return -EINVAL;
  93
  94         pac = sock_kmalloc(sk, sizeof(struct ipv6_ac_socklist), GFP_KERNEL);
  95         if (pac == NULL)
  96                 return -ENOMEM;
  97         pac->acl_next = NULL;
  98         ipv6_addr_copy(&pac->acl_addr, addr);
  99
 100         if (ifindex == 0) {
 101                 struct rt6_info *rt;
 102
 103                 rt = rt6_lookup(addr, NULL, 0, 0);
 104                 if (rt) {
 105                         dev = rt->rt6i_dev;
 106                         dev_hold(dev);
 107                         dst_release(&rt->u.dst);
 108                 } else if (ishost) {
 109                         err = -EADDRNOTAVAIL;
 110                         goto out_free_pac;
 111                 } else {
 112                         /* router, no matching interface: just pick one */
 113
 114                         dev = dev_get_by_flags(IFF_UP, IFF_UP|IFF_LOOPBACK);
 115                 }
 116         } else
 117                 dev = dev_get_by_index(ifindex);
 118
 119         if (dev == NULL) {
 120                 err = -ENODEV;
 121                 goto out_free_pac;
 122         }
 123
 124         idev = in6_dev_get(dev);
 125         if (!idev) {
 126                 if (ifindex)
 127                         err = -ENODEV;
 128                 else
 129                         err = -EADDRNOTAVAIL;
 130                 goto out_dev_put;
 131         }
 132         /* reset ishost, now that we have a specific device */
 133         ishost = !idev->cnf.forwarding;
 134         in6_dev_put(idev);
 135
 136         pac->acl_ifindex = dev->ifindex;
 137
 138         /* XXX
 139          * For hosts, allow link-local or matching prefix anycasts.
 140          * This obviates the need for propagating anycast routes while
 141          * still allowing some non-router anycast participation.
 142          */
 143         if (!ip6_onlink(addr, dev)) {
 144                 if (ishost)
 145                         err = -EADDRNOTAVAIL;
 146                 if (err)
 147                         goto out_dev_put;
 148         }
 149
 150         err = ipv6_dev_ac_inc(dev, addr);
 151         if (err)
 152                 goto out_dev_put;
 153
 154         write_lock_bh(&ipv6_sk_ac_lock);
 155         pac->acl_next = np->ipv6_ac_list;
 156         np->ipv6_ac_list = pac;
 157         write_unlock_bh(&ipv6_sk_ac_lock);
 158
 159         dev_put(dev);
 160
 161         return 0;
 162
 163 out_dev_put:
 164         dev_put(dev);
 165 out_free_pac:
 166         sock_kfree_s(sk, pac, sizeof(*pac));
 167         return err;
 168 }
 169
 170 /*
 171  *      socket leave an anycast group
 172  */
 173 int ipv6_sock_ac_drop(struct sock *sk, int ifindex, struct in6_addr *addr)
 174 {
 175         struct ipv6_pinfo *np = inet6_sk(sk);
 176         struct net_device *dev;
 177         struct ipv6_ac_socklist *pac, *prev_pac;
 178
 179         write_lock_bh(&ipv6_sk_ac_lock);
 180         prev_pac = NULL;
 181         for (pac = np->ipv6_ac_list; pac; pac = pac->acl_next) {
 182                 if ((ifindex == 0 || pac->acl_ifindex == ifindex) &&
 183                      ipv6_addr_equal(&pac->acl_addr, addr))
 184                         break;
 185                 prev_pac = pac;
 186         }
 187         if (!pac) {
 188                 write_unlock_bh(&ipv6_sk_ac_lock);
 189                 return -ENOENT;
 190         }
 191         if (prev_pac)
 192                 prev_pac->acl_next = pac->acl_next;
 193         else
 194                 np->ipv6_ac_list = pac->acl_next;
 195
 196         write_unlock_bh(&ipv6_sk_ac_lock);
 197
 198         dev = dev_get_by_index(pac->acl_ifindex);
 199         if (dev) {
 200                 ipv6_dev_ac_dec(dev, &pac->acl_addr);
 201                 dev_put(dev);
 202         }
 203         sock_kfree_s(sk, pac, sizeof(*pac));
 204         return 0;
 205 }
 206
 207 void ipv6_sock_ac_close(struct sock *sk)
 208 {
 209         struct ipv6_pinfo *np = inet6_sk(sk);
 210         struct net_device *dev = NULL;
 211         struct ipv6_ac_socklist *pac;
 212         int     prev_index;
 213
 214         write_lock_bh(&ipv6_sk_ac_lock);
 215         pac = np->ipv6_ac_list;
 216         np->ipv6_ac_list = NULL;
 217         write_unlock_bh(&ipv6_sk_ac_lock);
 218
 219         prev_index = 0;
 220         while (pac) {
 221                 struct ipv6_ac_socklist *next = pac->acl_next;
 222
 223                 if (pac->acl_ifindex != prev_index) {
 224                         if (dev)
 225                                 dev_put(dev);
 226                         dev = dev_get_by_index(pac->acl_ifindex);
 227                         prev_index = pac->acl_ifindex;
 228                 }
 229                 if (dev)
 230                         ipv6_dev_ac_dec(dev, &pac->acl_addr);
 231                 sock_kfree_s(sk, pac, sizeof(*pac));
 232                 pac = next;
 233         }
 234         if (dev)
 235                 dev_put(dev);
 236 }
 237
 238 #if 0
 239 /* The function is not used, which is funny. Apparently, author
 240  * supposed to use it to filter out datagrams inside udp/raw but forgot.
 241  *
 242  * It is OK, anycasts are not special comparing to delivery to unicasts.
 243  */
 244
 245 int inet6_ac_check(struct sock *sk, struct in6_addr *addr, int ifindex)
 246 {
 247         struct ipv6_ac_socklist *pac;
 248         struct ipv6_pinfo *np = inet6_sk(sk);
 249         int     found;
 250
 251         found = 0;
 252         read_lock(&ipv6_sk_ac_lock);
 253         for (pac=np->ipv6_ac_list; pac; pac=pac->acl_next) {
 254                 if (ifindex && pac->acl_ifindex != ifindex)
 255                         continue;
 256                 found = ipv6_addr_equal(&pac->acl_addr, addr);
 257                 if (found)
 258                         break;
 259         }
 260         read_unlock(&ipv6_sk_ac_lock);
 261
 262         return found;
 263 }
 264
 265 #endif
 266
 267 static void aca_put(struct ifacaddr6 *ac)
 268 {
 269         if (atomic_dec_and_test(&ac->aca_refcnt)) {
 270                 in6_dev_put(ac->aca_idev);
 271                 dst_release(&ac->aca_rt->u.dst);
 272                 kfree(ac);
 273         }
 274 }
 275
 276 /*
 277  *      device anycast group inc (add if not found)
 278  */
 279 int ipv6_dev_ac_inc(struct net_device *dev, struct in6_addr *addr)
 280 {
 281         struct ifacaddr6 *aca;
 282         struct inet6_dev *idev;
 283         struct rt6_info *rt;
 284         int err;
 285
 286         idev = in6_dev_get(dev);
 287
 288         if (idev == NULL)
 289                 return -EINVAL;
 290
 291         write_lock_bh(&idev->lock);
 292         if (idev->dead) {
 293                 err = -ENODEV;
 294                 goto out;
 295         }
 296
 297         for (aca = idev->ac_list; aca; aca = aca->aca_next) {
 298                 if (ipv6_addr_equal(&aca->aca_addr, addr)) {
 299                         aca->aca_users++;
 300                         err = 0;
 301                         goto out;
 302                 }
 303         }
 304
 305         /*
 306          *      not found: create a new one.
 307          */
 308
 309         aca = kzalloc(sizeof(struct ifacaddr6), GFP_ATOMIC);
 310
 311         if (aca == NULL) {
 312                 err = -ENOMEM;
 313                 goto out;
 314         }
 315
 316         rt = addrconf_dst_alloc(idev, addr, 1);
 317         if (IS_ERR(rt)) {
 318                 kfree(aca);
 319                 err = PTR_ERR(rt);
 320                 goto out;
 321         }
 322
 323         ipv6_addr_copy(&aca->aca_addr, addr);
 324         aca->aca_idev = idev;
 325         aca->aca_rt = rt;
 326         aca->aca_users = 1;
 327         /* aca_tstamp should be updated upon changes */
 328         aca->aca_cstamp = aca->aca_tstamp = jiffies;
 329         atomic_set(&aca->aca_refcnt, 2);
 330         spin_lock_init(&aca->aca_lock);
 331
 332         aca->aca_next = idev->ac_list;
 333         idev->ac_list = aca;
 334         write_unlock_bh(&idev->lock);
 335
 336         dst_hold(&rt->u.dst);
 337         if (ip6_ins_rt(rt))
 338                 dst_release(&rt->u.dst);
 339
 340         addrconf_join_solict(dev, &aca->aca_addr);
 341
 342         aca_put(aca);
 343         return 0;
 344 out:
 345         write_unlock_bh(&idev->lock);
 346         in6_dev_put(idev);
 347         return err;
 348 }
 349
 350 /*
 351  *      device anycast group decrement
 352  */
 353 int __ipv6_dev_ac_dec(struct inet6_dev *idev, struct in6_addr *addr)
 354 {
 355         struct ifacaddr6 *aca, *prev_aca;
 356
 357         write_lock_bh(&idev->lock);
 358         prev_aca = NULL;
 359         for (aca = idev->ac_list; aca; aca = aca->aca_next) {
 360                 if (ipv6_addr_equal(&aca->aca_addr, addr))
 361                         break;
 362                 prev_aca = aca;
 363         }
 364         if (!aca) {
 365                 write_unlock_bh(&idev->lock);
 366                 return -ENOENT;
 367         }
 368         if (--aca->aca_users > 0) {
 369                 write_unlock_bh(&idev->lock);
 370                 return 0;
 371         }
 372         if (prev_aca)
 373                 prev_aca->aca_next = aca->aca_next;
 374         else
 375                 idev->ac_list = aca->aca_next;
 376         write_unlock_bh(&idev->lock);
 377         addrconf_leave_solict(idev, &aca->aca_addr);
 378
 379         dst_hold(&aca->aca_rt->u.dst);
 380         if (ip6_del_rt(aca->aca_rt))
 381                 dst_free(&aca->aca_rt->u.dst);
 382         else
 383                 dst_release(&aca->aca_rt->u.dst);
 384
 385         aca_put(aca);
 386         return 0;
 387 }
 388
 389 static int ipv6_dev_ac_dec(struct net_device *dev, struct in6_addr *addr)
 390 {
 391         int ret;
 392         struct inet6_dev *idev = in6_dev_get(dev);
 393         if (idev == NULL)
 394                 return -ENODEV;
 395         ret = __ipv6_dev_ac_dec(idev, addr);
 396         in6_dev_put(idev);
 397         return ret;
 398 }
 399
 400 /*
 401  *      check if the interface has this anycast address
 402  */
 403 static int ipv6_chk_acast_dev(struct net_device *dev, struct in6_addr *addr)
 404 {
 405         struct inet6_dev *idev;
 406         struct ifacaddr6 *aca;
 407
 408         idev = in6_dev_get(dev);
 409         if (idev) {
 410                 read_lock_bh(&idev->lock);
 411                 for (aca = idev->ac_list; aca; aca = aca->aca_next)
 412                         if (ipv6_addr_equal(&aca->aca_addr, addr))
 413                                 break;
 414                 read_unlock_bh(&idev->lock);
 415                 in6_dev_put(idev);
 416                 return aca != 0;
 417         }
 418         return 0;
 419 }
 420
 421 /*
 422  *      check if given interface (or any, if dev==0) has this anycast address
 423  */
 424 int ipv6_chk_acast_addr(struct net_device *dev, struct in6_addr *addr)
 425 {
 426         int found = 0;
 427
 428         if (dev)
 429                 return ipv6_chk_acast_dev(dev, addr);
 430         read_lock(&dev_base_lock);
 431         for_each_netdev(dev)
 432                 if (ipv6_chk_acast_dev(dev, addr)) {
 433                         found = 1;
 434                         break;
 435                 }
 436         read_unlock(&dev_base_lock);
 437         return found;
 438 }
 439
 440
 441 #ifdef CONFIG_PROC_FS
 442 struct ac6_iter_state {
 443         struct net_device *dev;
 444         struct inet6_dev *idev;
 445 };
 446
 447 #define ac6_seq_private(seq)    ((struct ac6_iter_state *)(seq)->private)
 448
 449 static inline struct ifacaddr6 *ac6_get_first(struct seq_file *seq)
 450 {
 451         struct ifacaddr6 *im = NULL;
 452         struct ac6_iter_state *state = ac6_seq_private(seq);
 453
 454         state->idev = NULL;
 455         for_each_netdev(state->dev) {
 456                 struct inet6_dev *idev;
 457                 idev = in6_dev_get(state->dev);
 458                 if (!idev)
 459                         continue;
 460                 read_lock_bh(&idev->lock);
 461                 im = idev->ac_list;
 462                 if (im) {
 463                         state->idev = idev;
 464                         break;
 465                 }
 466                 read_unlock_bh(&idev->lock);
 467                 in6_dev_put(idev);
 468         }
 469         return im;
 470 }
 471
 472 static struct ifacaddr6 *ac6_get_next(struct seq_file *seq, struct ifacaddr6 *im)
 473 {
 474         struct ac6_iter_state *state = ac6_seq_private(seq);
 475
 476         im = im->aca_next;
 477         while (!im) {
 478                 if (likely(state->idev != NULL)) {
 479                         read_unlock_bh(&state->idev->lock);
 480                         in6_dev_put(state->idev);
 481                 }
 482                 state->dev = next_net_device(state->dev);
 483                 if (!state->dev) {
 484                         state->idev = NULL;
 485                         break;
 486                 }
 487                 state->idev = in6_dev_get(state->dev);
 488                 if (!state->idev)
 489                         continue;
 490                 read_lock_bh(&state->idev->lock);
 491                 im = state->idev->ac_list;
 492         }
 493         return im;
 494 }
 495
 496 static struct ifacaddr6 *ac6_get_idx(struct seq_file *seq, loff_t pos)
 497 {
 498         struct ifacaddr6 *im = ac6_get_first(seq);
 499         if (im)
 500                 while (pos && (im = ac6_get_next(seq, im)) != NULL)
 501                         --pos;
 502         return pos ? NULL : im;
 503 }
 504
 505 static void *ac6_seq_start(struct seq_file *seq, loff_t *pos)
 506 {
 507         read_lock(&dev_base_lock);
 508         return ac6_get_idx(seq, *pos);
 509 }
 510
 511 static void *ac6_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 512 {
 513         struct ifacaddr6 *im;
 514         im = ac6_get_next(seq, v);
 515         ++*pos;
 516         return im;
 517 }
 518
 519 static void ac6_seq_stop(struct seq_file *seq, void *v)
 520 {
 521         struct ac6_iter_state *state = ac6_seq_private(seq);
 522         if (likely(state->idev != NULL)) {
 523                 read_unlock_bh(&state->idev->lock);
 524                 in6_dev_put(state->idev);
 525         }
 526         read_unlock(&dev_base_lock);
 527 }
 528
 529 static int ac6_seq_show(struct seq_file *seq, void *v)
 530 {
 531         struct ifacaddr6 *im = (struct ifacaddr6 *)v;
 532         struct ac6_iter_state *state = ac6_seq_private(seq);
 533
 534         seq_printf(seq,
 535                    "%-4d %-15s " NIP6_SEQFMT " %5d\n",
 536                    state->dev->ifindex, state->dev->name,
 537                    NIP6(im->aca_addr),
 538                    im->aca_users);
 539         return 0;
 540 }
 541
 542 static const struct seq_operations ac6_seq_ops = {
 543         .start  =       ac6_seq_start,
 544         .next   =       ac6_seq_next,
 545         .stop   =       ac6_seq_stop,
 546         .show   =       ac6_seq_show,
 547 };
 548
 549 static int ac6_seq_open(struct inode *inode, struct file *file)
 550 {
 551         struct seq_file *seq;
 552         int rc = -ENOMEM;
 553         struct ac6_iter_state *s = kzalloc(sizeof(*s), GFP_KERNEL);
 554
 555         if (!s)
 556                 goto out;
 557
 558         rc = seq_open(file, &ac6_seq_ops);
 559         if (rc)
 560                 goto out_kfree;
 561
 562         seq = file->private_data;
 563         seq->private = s;
 564 out:
 565         return rc;
 566 out_kfree:
 567         kfree(s);
 568         goto out;
 569 }
 570
 571 static const struct file_operations ac6_seq_fops = {
 572         .owner          =       THIS_MODULE,
 573         .open           =       ac6_seq_open,
 574         .read           =       seq_read,
 575         .llseek         =       seq_lseek,
 576         .release        =       seq_release_private,
 577 };
 578
 579 int __init ac6_proc_init(void)
 580 {
 581         if (!proc_net_fops_create("anycast6", S_IRUGO, &ac6_seq_fops))
 582                 return -ENOMEM;
 583
 584         return 0;
 585 }
 586
 587 void ac6_proc_exit(void)
 588 {
 589         proc_net_remove("anycast6");
 590 }
 591 #endif
 592