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/config.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/sched.h>
  25 #include <linux/net.h>
  26 #include <linux/in6.h>
  27 #include <linux/netdevice.h>
  28 #include <linux/if_arp.h>
  29 #include <linux/route.h>
  30 #include <linux/init.h>
  31 #include <linux/proc_fs.h>
  32 #include <linux/seq_file.h>
  33
  34 #include <net/sock.h>
  35 #include <net/snmp.h>
  36
  37 #include <net/ipv6.h>
  38 #include <net/protocol.h>
  39 #include <net/if_inet6.h>
  40 #include <net/ndisc.h>
  41 #include <net/addrconf.h>
  42 #include <net/ip6_route.h>
  43
  44 #include <net/checksum.h>
  45
  46 static int ipv6_dev_ac_dec(struct net_device *dev, struct in6_addr *addr);
  47
  48 /* Big ac list lock for all the sockets */
  49 static DEFINE_RWLOCK(ipv6_sk_ac_lock);
  50
  51 /* XXX ip6_addr_match() and ip6_onlink() really belong in net/core.c */
  52
  53 static int
  54 ip6_addr_match(struct in6_addr *addr1, struct in6_addr *addr2, int prefix)
  55 {
  56         __u32   mask;
  57         int     i;
  58
  59         if (prefix > 128 || prefix < 0)
  60                 return 0;
  61         if (prefix == 0)
  62                 return 1;
  63         for (i=0; i<4; ++i) {
  64                 if (prefix >= 32)
  65                         mask = ~0;
  66                 else
  67                         mask = htonl(~0 << (32 - prefix));
  68                 if ((addr1->s6_addr32[i] ^ addr2->s6_addr32[i]) & mask)
  69                         return 0;
  70                 prefix -= 32;
  71                 if (prefix <= 0)
  72                         break;
  73         }
  74         return 1;
  75 }
  76
  77 static int
  78 ip6_onlink(struct in6_addr *addr, struct net_device *dev)
  79 {
  80         struct inet6_dev        *idev;
  81         struct inet6_ifaddr     *ifa;
  82         int     onlink;
  83
  84         onlink = 0;
  85         read_lock(&addrconf_lock);
  86         idev = __in6_dev_get(dev);
  87         if (idev) {
  88                 read_lock_bh(&idev->lock);
  89                 for (ifa=idev->addr_list; ifa; ifa=ifa->if_next) {
  90                         onlink = ip6_addr_match(addr, &ifa->addr,
  91                                         ifa->prefix_len);
  92                         if (onlink)
  93                                 break;
  94                 }
  95                 read_unlock_bh(&idev->lock);
  96         }
  97         read_unlock(&addrconf_lock);
  98         return onlink;
  99 }
 100
 101 /*
 102  *      socket join an anycast group
 103  */
 104
 105 int ipv6_sock_ac_join(struct sock *sk, int ifindex, struct in6_addr *addr)
 106 {
 107         struct ipv6_pinfo *np = inet6_sk(sk);
 108         struct net_device *dev = NULL;
 109         struct inet6_dev *idev;
 110         struct ipv6_ac_socklist *pac;
 111         int     ishost = !ipv6_devconf.forwarding;
 112         int     err = 0;
 113
 114         if (!capable(CAP_NET_ADMIN))
 115                 return -EPERM;
 116         if (ipv6_addr_is_multicast(addr))
 117                 return -EINVAL;
 118         if (ipv6_chk_addr(addr, NULL, 0))
 119                 return -EINVAL;
 120
 121         pac = sock_kmalloc(sk, sizeof(struct ipv6_ac_socklist), GFP_KERNEL);
 122         if (pac == NULL)
 123                 return -ENOMEM;
 124         pac->acl_next = NULL;
 125         ipv6_addr_copy(&pac->acl_addr, addr);
 126
 127         if (ifindex == 0) {
 128                 struct rt6_info *rt;
 129
 130                 rt = rt6_lookup(addr, NULL, 0, 0);
 131                 if (rt) {
 132                         dev = rt->rt6i_dev;
 133                         dev_hold(dev);
 134                         dst_release(&rt->u.dst);
 135                 } else if (ishost) {
 136                         err = -EADDRNOTAVAIL;
 137                         goto out_free_pac;
 138                 } else {
 139                         /* router, no matching interface: just pick one */
 140
 141                         dev = dev_get_by_flags(IFF_UP, IFF_UP|IFF_LOOPBACK);
 142                 }
 143         } else
 144                 dev = dev_get_by_index(ifindex);
 145
 146         if (dev == NULL) {
 147                 err = -ENODEV;
 148                 goto out_free_pac;
 149         }
 150
 151         idev = in6_dev_get(dev);
 152         if (!idev) {
 153                 if (ifindex)
 154                         err = -ENODEV;
 155                 else
 156                         err = -EADDRNOTAVAIL;
 157                 goto out_dev_put;
 158         }
 159         /* reset ishost, now that we have a specific device */
 160         ishost = !idev->cnf.forwarding;
 161         in6_dev_put(idev);
 162
 163         pac->acl_ifindex = dev->ifindex;
 164
 165         /* XXX
 166          * For hosts, allow link-local or matching prefix anycasts.
 167          * This obviates the need for propagating anycast routes while
 168          * still allowing some non-router anycast participation.
 169          */
 170         if (!ip6_onlink(addr, dev)) {
 171                 if (ishost)
 172                         err = -EADDRNOTAVAIL;
 173                 if (err)
 174                         goto out_dev_put;
 175         }
 176
 177         err = ipv6_dev_ac_inc(dev, addr);
 178         if (err)
 179                 goto out_dev_put;
 180
 181         write_lock_bh(&ipv6_sk_ac_lock);
 182         pac->acl_next = np->ipv6_ac_list;
 183         np->ipv6_ac_list = pac;
 184         write_unlock_bh(&ipv6_sk_ac_lock);
 185
 186         dev_put(dev);
 187
 188         return 0;
 189
 190 out_dev_put:
 191         dev_put(dev);
 192 out_free_pac:
 193         sock_kfree_s(sk, pac, sizeof(*pac));
 194         return err;
 195 }
 196
 197 /*
 198  *      socket leave an anycast group
 199  */
 200 int ipv6_sock_ac_drop(struct sock *sk, int ifindex, struct in6_addr *addr)
 201 {
 202         struct ipv6_pinfo *np = inet6_sk(sk);
 203         struct net_device *dev;
 204         struct ipv6_ac_socklist *pac, *prev_pac;
 205
 206         write_lock_bh(&ipv6_sk_ac_lock);
 207         prev_pac = NULL;
 208         for (pac = np->ipv6_ac_list; pac; pac = pac->acl_next) {
 209                 if ((ifindex == 0 || pac->acl_ifindex == ifindex) &&
 210                      ipv6_addr_equal(&pac->acl_addr, addr))
 211                         break;
 212                 prev_pac = pac;
 213         }
 214         if (!pac) {
 215                 write_unlock_bh(&ipv6_sk_ac_lock);
 216                 return -ENOENT;
 217         }
 218         if (prev_pac)
 219                 prev_pac->acl_next = pac->acl_next;
 220         else
 221                 np->ipv6_ac_list = pac->acl_next;
 222
 223         write_unlock_bh(&ipv6_sk_ac_lock);
 224
 225         dev = dev_get_by_index(pac->acl_ifindex);
 226         if (dev) {
 227                 ipv6_dev_ac_dec(dev, &pac->acl_addr);
 228                 dev_put(dev);
 229         }
 230         sock_kfree_s(sk, pac, sizeof(*pac));
 231         return 0;
 232 }
 233
 234 void ipv6_sock_ac_close(struct sock *sk)
 235 {
 236         struct ipv6_pinfo *np = inet6_sk(sk);
 237         struct net_device *dev = NULL;
 238         struct ipv6_ac_socklist *pac;
 239         int     prev_index;
 240
 241         write_lock_bh(&ipv6_sk_ac_lock);
 242         pac = np->ipv6_ac_list;
 243         np->ipv6_ac_list = NULL;
 244         write_unlock_bh(&ipv6_sk_ac_lock);
 245
 246         prev_index = 0;
 247         while (pac) {
 248                 struct ipv6_ac_socklist *next = pac->acl_next;
 249
 250                 if (pac->acl_ifindex != prev_index) {
 251                         if (dev)
 252                                 dev_put(dev);
 253                         dev = dev_get_by_index(pac->acl_ifindex);
 254                         prev_index = pac->acl_ifindex;
 255                 }
 256                 if (dev)
 257                         ipv6_dev_ac_dec(dev, &pac->acl_addr);
 258                 sock_kfree_s(sk, pac, sizeof(*pac));
 259                 pac = next;
 260         }
 261         if (dev)
 262                 dev_put(dev);
 263 }
 264
 265 #if 0
 266 /* The function is not used, which is funny. Apparently, author
 267  * supposed to use it to filter out datagrams inside udp/raw but forgot.
 268  *
 269  * It is OK, anycasts are not special comparing to delivery to unicasts.
 270  */
 271
 272 int inet6_ac_check(struct sock *sk, struct in6_addr *addr, int ifindex)
 273 {
 274         struct ipv6_ac_socklist *pac;
 275         struct ipv6_pinfo *np = inet6_sk(sk);
 276         int     found;
 277
 278         found = 0;
 279         read_lock(&ipv6_sk_ac_lock);
 280         for (pac=np->ipv6_ac_list; pac; pac=pac->acl_next) {
 281                 if (ifindex && pac->acl_ifindex != ifindex)
 282                         continue;
 283                 found = ipv6_addr_equal(&pac->acl_addr, addr);
 284                 if (found)
 285                         break;
 286         }
 287         read_unlock(&ipv6_sk_ac_lock);
 288
 289         return found;
 290 }
 291
 292 #endif
 293
 294 static void aca_put(struct ifacaddr6 *ac)
 295 {
 296         if (atomic_dec_and_test(&ac->aca_refcnt)) {
 297                 in6_dev_put(ac->aca_idev);
 298                 dst_release(&ac->aca_rt->u.dst);
 299                 kfree(ac);
 300         }
 301 }
 302
 303 /*
 304  *      device anycast group inc (add if not found)
 305  */
 306 int ipv6_dev_ac_inc(struct net_device *dev, struct in6_addr *addr)
 307 {
 308         struct ifacaddr6 *aca;
 309         struct inet6_dev *idev;
 310         struct rt6_info *rt;
 311         int err;
 312
 313         idev = in6_dev_get(dev);
 314
 315         if (idev == NULL)
 316                 return -EINVAL;
 317
 318         write_lock_bh(&idev->lock);
 319         if (idev->dead) {
 320                 err = -ENODEV;
 321                 goto out;
 322         }
 323
 324         for (aca = idev->ac_list; aca; aca = aca->aca_next) {
 325                 if (ipv6_addr_equal(&aca->aca_addr, addr)) {
 326                         aca->aca_users++;
 327                         err = 0;
 328                         goto out;
 329                 }
 330         }
 331
 332         /*
 333          *      not found: create a new one.
 334          */
 335
 336         aca = kmalloc(sizeof(struct ifacaddr6), GFP_ATOMIC);
 337
 338         if (aca == NULL) {
 339                 err = -ENOMEM;
 340                 goto out;
 341         }
 342
 343         rt = addrconf_dst_alloc(idev, addr, 1);
 344         if (IS_ERR(rt)) {
 345                 kfree(aca);
 346                 err = PTR_ERR(rt);
 347                 goto out;
 348         }
 349
 350         memset(aca, 0, sizeof(struct ifacaddr6));
 351
 352         ipv6_addr_copy(&aca->aca_addr, addr);
 353         aca->aca_idev = idev;
 354         aca->aca_rt = rt;
 355         aca->aca_users = 1;
 356         /* aca_tstamp should be updated upon changes */
 357         aca->aca_cstamp = aca->aca_tstamp = jiffies;
 358         atomic_set(&aca->aca_refcnt, 2);
 359         spin_lock_init(&aca->aca_lock);
 360
 361         aca->aca_next = idev->ac_list;
 362         idev->ac_list = aca;
 363         write_unlock_bh(&idev->lock);
 364
 365         dst_hold(&rt->u.dst);
 366         if (ip6_ins_rt(rt, NULL, NULL))
 367                 dst_release(&rt->u.dst);
 368
 369         addrconf_join_solict(dev, &aca->aca_addr);
 370
 371         aca_put(aca);
 372         return 0;
 373 out:
 374         write_unlock_bh(&idev->lock);
 375         in6_dev_put(idev);
 376         return err;
 377 }
 378
 379 /*
 380  *      device anycast group decrement
 381  */
 382 int __ipv6_dev_ac_dec(struct inet6_dev *idev, struct in6_addr *addr)
 383 {
 384         struct ifacaddr6 *aca, *prev_aca;
 385
 386         write_lock_bh(&idev->lock);
 387         prev_aca = NULL;
 388         for (aca = idev->ac_list; aca; aca = aca->aca_next) {
 389                 if (ipv6_addr_equal(&aca->aca_addr, addr))
 390                         break;
 391                 prev_aca = aca;
 392         }
 393         if (!aca) {
 394                 write_unlock_bh(&idev->lock);
 395                 return -ENOENT;
 396         }
 397         if (--aca->aca_users > 0) {
 398                 write_unlock_bh(&idev->lock);
 399                 return 0;
 400         }
 401         if (prev_aca)
 402                 prev_aca->aca_next = aca->aca_next;
 403         else
 404                 idev->ac_list = aca->aca_next;
 405         write_unlock_bh(&idev->lock);
 406         addrconf_leave_solict(idev, &aca->aca_addr);
 407
 408         dst_hold(&aca->aca_rt->u.dst);
 409         if (ip6_del_rt(aca->aca_rt, NULL, NULL))
 410                 dst_free(&aca->aca_rt->u.dst);
 411         else
 412                 dst_release(&aca->aca_rt->u.dst);
 413
 414         aca_put(aca);
 415         return 0;
 416 }
 417
 418 static int ipv6_dev_ac_dec(struct net_device *dev, struct in6_addr *addr)
 419 {
 420         int ret;
 421         struct inet6_dev *idev = in6_dev_get(dev);
 422         if (idev == NULL)
 423                 return -ENODEV;
 424         ret = __ipv6_dev_ac_dec(idev, addr);
 425         in6_dev_put(idev);
 426         return ret;
 427 }
 428
 429 /*
 430  *      check if the interface has this anycast address
 431  */
 432 static int ipv6_chk_acast_dev(struct net_device *dev, struct in6_addr *addr)
 433 {
 434         struct inet6_dev *idev;
 435         struct ifacaddr6 *aca;
 436
 437         idev = in6_dev_get(dev);
 438         if (idev) {
 439                 read_lock_bh(&idev->lock);
 440                 for (aca = idev->ac_list; aca; aca = aca->aca_next)
 441                         if (ipv6_addr_equal(&aca->aca_addr, addr))
 442                                 break;
 443                 read_unlock_bh(&idev->lock);
 444                 in6_dev_put(idev);
 445                 return aca != 0;
 446         }
 447         return 0;
 448 }
 449
 450 /*
 451  *      check if given interface (or any, if dev==0) has this anycast address
 452  */
 453 int ipv6_chk_acast_addr(struct net_device *dev, struct in6_addr *addr)
 454 {
 455         if (dev)
 456                 return ipv6_chk_acast_dev(dev, addr);
 457         read_lock(&dev_base_lock);
 458         for (dev=dev_base; dev; dev=dev->next)
 459                 if (ipv6_chk_acast_dev(dev, addr))
 460                         break;
 461         read_unlock(&dev_base_lock);
 462         return dev != 0;
 463 }
 464
 465
 466 #ifdef CONFIG_PROC_FS
 467 struct ac6_iter_state {
 468         struct net_device *dev;
 469         struct inet6_dev *idev;
 470 };
 471
 472 #define ac6_seq_private(seq)    ((struct ac6_iter_state *)(seq)->private)
 473
 474 static inline struct ifacaddr6 *ac6_get_first(struct seq_file *seq)
 475 {
 476         struct ifacaddr6 *im = NULL;
 477         struct ac6_iter_state *state = ac6_seq_private(seq);
 478
 479         for (state->dev = dev_base, state->idev = NULL;
 480              state->dev;
 481              state->dev = state->dev->next) {
 482                 struct inet6_dev *idev;
 483                 idev = in6_dev_get(state->dev);
 484                 if (!idev)
 485                         continue;
 486                 read_lock_bh(&idev->lock);
 487                 im = idev->ac_list;
 488                 if (im) {
 489                         state->idev = idev;
 490                         break;
 491                 }
 492                 read_unlock_bh(&idev->lock);
 493         }
 494         return im;
 495 }
 496
 497 static struct ifacaddr6 *ac6_get_next(struct seq_file *seq, struct ifacaddr6 *im)
 498 {
 499         struct ac6_iter_state *state = ac6_seq_private(seq);
 500
 501         im = im->aca_next;
 502         while (!im) {
 503                 if (likely(state->idev != NULL)) {
 504                         read_unlock_bh(&state->idev->lock);
 505                         in6_dev_put(state->idev);
 506                 }
 507                 state->dev = state->dev->next;
 508                 if (!state->dev) {
 509                         state->idev = NULL;
 510                         break;
 511                 }
 512                 state->idev = in6_dev_get(state->dev);
 513                 if (!state->idev)
 514                         continue;
 515                 read_lock_bh(&state->idev->lock);
 516                 im = state->idev->ac_list;
 517         }
 518         return im;
 519 }
 520
 521 static struct ifacaddr6 *ac6_get_idx(struct seq_file *seq, loff_t pos)
 522 {
 523         struct ifacaddr6 *im = ac6_get_first(seq);
 524         if (im)
 525                 while (pos && (im = ac6_get_next(seq, im)) != NULL)
 526                         --pos;
 527         return pos ? NULL : im;
 528 }
 529
 530 static void *ac6_seq_start(struct seq_file *seq, loff_t *pos)
 531 {
 532         read_lock(&dev_base_lock);
 533         return ac6_get_idx(seq, *pos);
 534 }
 535
 536 static void *ac6_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 537 {
 538         struct ifacaddr6 *im;
 539         im = ac6_get_next(seq, v);
 540         ++*pos;
 541         return im;
 542 }
 543
 544 static void ac6_seq_stop(struct seq_file *seq, void *v)
 545 {
 546         struct ac6_iter_state *state = ac6_seq_private(seq);
 547         if (likely(state->idev != NULL)) {
 548                 read_unlock_bh(&state->idev->lock);
 549                 in6_dev_put(state->idev);
 550         }
 551         read_unlock(&dev_base_lock);
 552 }
 553
 554 static int ac6_seq_show(struct seq_file *seq, void *v)
 555 {
 556         struct ifacaddr6 *im = (struct ifacaddr6 *)v;
 557         struct ac6_iter_state *state = ac6_seq_private(seq);
 558
 559         seq_printf(seq,
 560                    "%-4d %-15s "
 561                    "%04x%04x%04x%04x%04x%04x%04x%04x "
 562                    "%5d\n",
 563                    state->dev->ifindex, state->dev->name,
 564                    NIP6(im->aca_addr),
 565                    im->aca_users);
 566         return 0;
 567 }
 568
 569 static struct seq_operations ac6_seq_ops = {
 570         .start  =       ac6_seq_start,
 571         .next   =       ac6_seq_next,
 572         .stop   =       ac6_seq_stop,
 573         .show   =       ac6_seq_show,
 574 };
 575
 576 static int ac6_seq_open(struct inode *inode, struct file *file)
 577 {
 578         struct seq_file *seq;
 579         int rc = -ENOMEM;
 580         struct ac6_iter_state *s = kmalloc(sizeof(*s), GFP_KERNEL);
 581
 582         if (!s)
 583                 goto out;
 584
 585         rc = seq_open(file, &ac6_seq_ops);
 586         if (rc)
 587                 goto out_kfree;
 588
 589         seq = file->private_data;
 590         seq->private = s;
 591         memset(s, 0, sizeof(*s));
 592 out:
 593         return rc;
 594 out_kfree:
 595         kfree(s);
 596         goto out;
 597 }
 598
 599 static struct file_operations ac6_seq_fops = {
 600         .owner          =       THIS_MODULE,
 601         .open           =       ac6_seq_open,
 602         .read           =       seq_read,
 603         .llseek         =       seq_lseek,
 604         .release        =       seq_release_private,
 605 };
 606
 607 int __init ac6_proc_init(void)
 608 {
 609         if (!proc_net_fops_create("anycast6", S_IRUGO, &ac6_seq_fops))
 610                 return -ENOMEM;
 611
 612         return 0;
 613 }
 614
 615 void ac6_proc_exit(void)
 616 {
 617         proc_net_remove("anycast6");
 618 }
 619 #endif
 620