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/config.h>
  18 #include <linux/module.h>
  19 #include <linux/errno.h>
  20 #include <linux/types.h>
  21 #include <linux/random.h>
  22 #include <linux/string.h>
  23 #include <linux/socket.h>
  24 #include <linux/sockios.h>
  25 #include <linux/sched.h>
  26 #include <linux/net.h>
  27 #include <linux/in6.h>
  28 #include <linux/netdevice.h>
  29 #include <linux/if_arp.h>
  30 #include <linux/route.h>
  31 #include <linux/init.h>
  32 #include <linux/proc_fs.h>
  33 #include <linux/seq_file.h>
  34
  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, struct in6_addr *addr);
  48
  49 /* Big ac list lock for all the sockets */
  50 static DEFINE_RWLOCK(ipv6_sk_ac_lock);
  51
  52 static int
  53 ip6_onlink(struct in6_addr *addr, struct net_device *dev)
  54 {
  55         struct inet6_dev        *idev;
  56         struct inet6_ifaddr     *ifa;
  57         int     onlink;
  58
  59         onlink = 0;
  60         read_lock(&addrconf_lock);
  61         idev = __in6_dev_get(dev);
  62         if (idev) {
  63                 read_lock_bh(&idev->lock);
  64                 for (ifa=idev->addr_list; ifa; ifa=ifa->if_next) {
  65                         onlink = ipv6_prefix_equal(addr, &ifa->addr,
  66                                                    ifa->prefix_len);
  67                         if (onlink)
  68                                 break;
  69                 }
  70                 read_unlock_bh(&idev->lock);
  71         }
  72         read_unlock(&addrconf_lock);
  73         return onlink;
  74 }
  75
  76 /*
  77  *      socket join an anycast group
  78  */
  79
  80 int ipv6_sock_ac_join(struct sock *sk, int ifindex, struct in6_addr *addr)
  81 {
  82         struct ipv6_pinfo *np = inet6_sk(sk);
  83         struct net_device *dev = NULL;
  84         struct inet6_dev *idev;
  85         struct ipv6_ac_socklist *pac;
  86         int     ishost = !ipv6_devconf.forwarding;
  87         int     err = 0;
  88
  89         if (!capable(CAP_NET_ADMIN))
  90                 return -EPERM;
  91         if (ipv6_addr_is_multicast(addr))
  92                 return -EINVAL;
  93         if (ipv6_chk_addr(addr, NULL, 0))
  94                 return -EINVAL;
  95
  96         pac = sock_kmalloc(sk, sizeof(struct ipv6_ac_socklist), GFP_KERNEL);
  97         if (pac == NULL)
  98                 return -ENOMEM;
  99         pac->acl_next = NULL;
 100         ipv6_addr_copy(&pac->acl_addr, addr);
 101
 102         if (ifindex == 0) {
 103                 struct rt6_info *rt;
 104
 105                 rt = rt6_lookup(addr, NULL, 0, 0);
 106                 if (rt) {
 107                         dev = rt->rt6i_dev;
 108                         dev_hold(dev);
 109                         dst_release(&rt->u.dst);
 110                 } else if (ishost) {
 111                         err = -EADDRNOTAVAIL;
 112                         goto out_free_pac;
 113                 } else {
 114                         /* router, no matching interface: just pick one */
 115
 116                         dev = dev_get_by_flags(IFF_UP, IFF_UP|IFF_LOOPBACK);
 117                 }
 118         } else
 119                 dev = dev_get_by_index(ifindex);
 120
 121         if (dev == NULL) {
 122                 err = -ENODEV;
 123                 goto out_free_pac;
 124         }
 125
 126         idev = in6_dev_get(dev);
 127         if (!idev) {
 128                 if (ifindex)
 129                         err = -ENODEV;
 130                 else
 131                         err = -EADDRNOTAVAIL;
 132                 goto out_dev_put;
 133         }
 134         /* reset ishost, now that we have a specific device */
 135         ishost = !idev->cnf.forwarding;
 136         in6_dev_put(idev);
 137
 138         pac->acl_ifindex = dev->ifindex;
 139
 140         /* XXX
 141          * For hosts, allow link-local or matching prefix anycasts.
 142          * This obviates the need for propagating anycast routes while
 143          * still allowing some non-router anycast participation.
 144          */
 145         if (!ip6_onlink(addr, dev)) {
 146                 if (ishost)
 147                         err = -EADDRNOTAVAIL;
 148                 if (err)
 149                         goto out_dev_put;
 150         }
 151
 152         err = ipv6_dev_ac_inc(dev, addr);
 153         if (err)
 154                 goto out_dev_put;
 155
 156         write_lock_bh(&ipv6_sk_ac_lock);
 157         pac->acl_next = np->ipv6_ac_list;
 158         np->ipv6_ac_list = pac;
 159         write_unlock_bh(&ipv6_sk_ac_lock);
 160
 161         dev_put(dev);
 162
 163         return 0;
 164
 165 out_dev_put:
 166         dev_put(dev);
 167 out_free_pac:
 168         sock_kfree_s(sk, pac, sizeof(*pac));
 169         return err;
 170 }
 171
 172 /*
 173  *      socket leave an anycast group
 174  */
 175 int ipv6_sock_ac_drop(struct sock *sk, int ifindex, struct in6_addr *addr)
 176 {
 177         struct ipv6_pinfo *np = inet6_sk(sk);
 178         struct net_device *dev;
 179         struct ipv6_ac_socklist *pac, *prev_pac;
 180
 181         write_lock_bh(&ipv6_sk_ac_lock);
 182         prev_pac = NULL;
 183         for (pac = np->ipv6_ac_list; pac; pac = pac->acl_next) {
 184                 if ((ifindex == 0 || pac->acl_ifindex == ifindex) &&
 185                      ipv6_addr_equal(&pac->acl_addr, addr))
 186                         break;
 187                 prev_pac = pac;
 188         }
 189         if (!pac) {
 190                 write_unlock_bh(&ipv6_sk_ac_lock);
 191                 return -ENOENT;
 192         }
 193         if (prev_pac)
 194                 prev_pac->acl_next = pac->acl_next;
 195         else
 196                 np->ipv6_ac_list = pac->acl_next;
 197
 198         write_unlock_bh(&ipv6_sk_ac_lock);
 199
 200         dev = dev_get_by_index(pac->acl_ifindex);
 201         if (dev) {
 202                 ipv6_dev_ac_dec(dev, &pac->acl_addr);
 203                 dev_put(dev);
 204         }
 205         sock_kfree_s(sk, pac, sizeof(*pac));
 206         return 0;
 207 }
 208
 209 void ipv6_sock_ac_close(struct sock *sk)
 210 {
 211         struct ipv6_pinfo *np = inet6_sk(sk);
 212         struct net_device *dev = NULL;
 213         struct ipv6_ac_socklist *pac;
 214         int     prev_index;
 215
 216         write_lock_bh(&ipv6_sk_ac_lock);
 217         pac = np->ipv6_ac_list;
 218         np->ipv6_ac_list = NULL;
 219         write_unlock_bh(&ipv6_sk_ac_lock);
 220
 221         prev_index = 0;
 222         while (pac) {
 223                 struct ipv6_ac_socklist *next = pac->acl_next;
 224
 225                 if (pac->acl_ifindex != prev_index) {
 226                         if (dev)
 227                                 dev_put(dev);
 228                         dev = dev_get_by_index(pac->acl_ifindex);
 229                         prev_index = pac->acl_ifindex;
 230                 }
 231                 if (dev)
 232                         ipv6_dev_ac_dec(dev, &pac->acl_addr);
 233                 sock_kfree_s(sk, pac, sizeof(*pac));
 234                 pac = next;
 235         }
 236         if (dev)
 237                 dev_put(dev);
 238 }
 239
 240 #if 0
 241 /* The function is not used, which is funny. Apparently, author
 242  * supposed to use it to filter out datagrams inside udp/raw but forgot.
 243  *
 244  * It is OK, anycasts are not special comparing to delivery to unicasts.
 245  */
 246
 247 int inet6_ac_check(struct sock *sk, struct in6_addr *addr, int ifindex)
 248 {
 249         struct ipv6_ac_socklist *pac;
 250         struct ipv6_pinfo *np = inet6_sk(sk);
 251         int     found;
 252
 253         found = 0;
 254         read_lock(&ipv6_sk_ac_lock);
 255         for (pac=np->ipv6_ac_list; pac; pac=pac->acl_next) {
 256                 if (ifindex && pac->acl_ifindex != ifindex)
 257                         continue;
 258                 found = ipv6_addr_equal(&pac->acl_addr, addr);
 259                 if (found)
 260                         break;
 261         }
 262         read_unlock(&ipv6_sk_ac_lock);
 263
 264         return found;
 265 }
 266
 267 #endif
 268
 269 static void aca_put(struct ifacaddr6 *ac)
 270 {
 271         if (atomic_dec_and_test(&ac->aca_refcnt)) {
 272                 in6_dev_put(ac->aca_idev);
 273                 dst_release(&ac->aca_rt->u.dst);
 274                 kfree(ac);
 275         }
 276 }
 277
 278 /*
 279  *      device anycast group inc (add if not found)
 280  */
 281 int ipv6_dev_ac_inc(struct net_device *dev, struct in6_addr *addr)
 282 {
 283         struct ifacaddr6 *aca;
 284         struct inet6_dev *idev;
 285         struct rt6_info *rt;
 286         int err;
 287
 288         idev = in6_dev_get(dev);
 289
 290         if (idev == NULL)
 291                 return -EINVAL;
 292
 293         write_lock_bh(&idev->lock);
 294         if (idev->dead) {
 295                 err = -ENODEV;
 296                 goto out;
 297         }
 298
 299         for (aca = idev->ac_list; aca; aca = aca->aca_next) {
 300                 if (ipv6_addr_equal(&aca->aca_addr, addr)) {
 301                         aca->aca_users++;
 302                         err = 0;
 303                         goto out;
 304                 }
 305         }
 306
 307         /*
 308          *      not found: create a new one.
 309          */
 310
 311         aca = kzalloc(sizeof(struct ifacaddr6), GFP_ATOMIC);
 312
 313         if (aca == NULL) {
 314                 err = -ENOMEM;
 315                 goto out;
 316         }
 317
 318         rt = addrconf_dst_alloc(idev, addr, 1);
 319         if (IS_ERR(rt)) {
 320                 kfree(aca);
 321                 err = PTR_ERR(rt);
 322                 goto out;
 323         }
 324
 325         ipv6_addr_copy(&aca->aca_addr, addr);
 326         aca->aca_idev = idev;
 327         aca->aca_rt = rt;
 328         aca->aca_users = 1;
 329         /* aca_tstamp should be updated upon changes */
 330         aca->aca_cstamp = aca->aca_tstamp = jiffies;
 331         atomic_set(&aca->aca_refcnt, 2);
 332         spin_lock_init(&aca->aca_lock);
 333
 334         aca->aca_next = idev->ac_list;
 335         idev->ac_list = aca;
 336         write_unlock_bh(&idev->lock);
 337
 338         dst_hold(&rt->u.dst);
 339         if (ip6_ins_rt(rt, NULL, NULL, NULL))
 340                 dst_release(&rt->u.dst);
 341
 342         addrconf_join_solict(dev, &aca->aca_addr);
 343
 344         aca_put(aca);
 345         return 0;
 346 out:
 347         write_unlock_bh(&idev->lock);
 348         in6_dev_put(idev);
 349         return err;
 350 }
 351
 352 /*
 353  *      device anycast group decrement
 354  */
 355 int __ipv6_dev_ac_dec(struct inet6_dev *idev, struct in6_addr *addr)
 356 {
 357         struct ifacaddr6 *aca, *prev_aca;
 358
 359         write_lock_bh(&idev->lock);
 360         prev_aca = NULL;
 361         for (aca = idev->ac_list; aca; aca = aca->aca_next) {
 362                 if (ipv6_addr_equal(&aca->aca_addr, addr))
 363                         break;
 364                 prev_aca = aca;
 365         }
 366         if (!aca) {
 367                 write_unlock_bh(&idev->lock);
 368                 return -ENOENT;
 369         }
 370         if (--aca->aca_users > 0) {
 371                 write_unlock_bh(&idev->lock);
 372                 return 0;
 373         }
 374         if (prev_aca)
 375                 prev_aca->aca_next = aca->aca_next;
 376         else
 377                 idev->ac_list = aca->aca_next;
 378         write_unlock_bh(&idev->lock);
 379         addrconf_leave_solict(idev, &aca->aca_addr);
 380
 381         dst_hold(&aca->aca_rt->u.dst);
 382         if (ip6_del_rt(aca->aca_rt, NULL, NULL, NULL))
 383                 dst_free(&aca->aca_rt->u.dst);
 384         else
 385                 dst_release(&aca->aca_rt->u.dst);
 386
 387         aca_put(aca);
 388         return 0;
 389 }
 390
 391 static int ipv6_dev_ac_dec(struct net_device *dev, struct in6_addr *addr)
 392 {
 393         int ret;
 394         struct inet6_dev *idev = in6_dev_get(dev);
 395         if (idev == NULL)
 396                 return -ENODEV;
 397         ret = __ipv6_dev_ac_dec(idev, addr);
 398         in6_dev_put(idev);
 399         return ret;
 400 }
 401
 402 /*
 403  *      check if the interface has this anycast address
 404  */
 405 static int ipv6_chk_acast_dev(struct net_device *dev, struct in6_addr *addr)
 406 {
 407         struct inet6_dev *idev;
 408         struct ifacaddr6 *aca;
 409
 410         idev = in6_dev_get(dev);
 411         if (idev) {
 412                 read_lock_bh(&idev->lock);
 413                 for (aca = idev->ac_list; aca; aca = aca->aca_next)
 414                         if (ipv6_addr_equal(&aca->aca_addr, addr))
 415                                 break;
 416                 read_unlock_bh(&idev->lock);
 417                 in6_dev_put(idev);
 418                 return aca != 0;
 419         }
 420         return 0;
 421 }
 422
 423 /*
 424  *      check if given interface (or any, if dev==0) has this anycast address
 425  */
 426 int ipv6_chk_acast_addr(struct net_device *dev, struct in6_addr *addr)
 427 {
 428         if (dev)
 429                 return ipv6_chk_acast_dev(dev, addr);
 430         read_lock(&dev_base_lock);
 431         for (dev=dev_base; dev; dev=dev->next)
 432                 if (ipv6_chk_acast_dev(dev, addr))
 433                         break;
 434         read_unlock(&dev_base_lock);
 435         return dev != 0;
 436 }
 437
 438
 439 #ifdef CONFIG_PROC_FS
 440 struct ac6_iter_state {
 441         struct net_device *dev;
 442         struct inet6_dev *idev;
 443 };
 444
 445 #define ac6_seq_private(seq)    ((struct ac6_iter_state *)(seq)->private)
 446
 447 static inline struct ifacaddr6 *ac6_get_first(struct seq_file *seq)
 448 {
 449         struct ifacaddr6 *im = NULL;
 450         struct ac6_iter_state *state = ac6_seq_private(seq);
 451
 452         for (state->dev = dev_base, state->idev = NULL;
 453              state->dev;
 454              state->dev = state->dev->next) {
 455                 struct inet6_dev *idev;
 456                 idev = in6_dev_get(state->dev);
 457                 if (!idev)
 458                         continue;
 459                 read_lock_bh(&idev->lock);
 460                 im = idev->ac_list;
 461                 if (im) {
 462                         state->idev = idev;
 463                         break;
 464                 }
 465                 read_unlock_bh(&idev->lock);
 466         }
 467         return im;
 468 }
 469
 470 static struct ifacaddr6 *ac6_get_next(struct seq_file *seq, struct ifacaddr6 *im)
 471 {
 472         struct ac6_iter_state *state = ac6_seq_private(seq);
 473
 474         im = im->aca_next;
 475         while (!im) {
 476                 if (likely(state->idev != NULL)) {
 477                         read_unlock_bh(&state->idev->lock);
 478                         in6_dev_put(state->idev);
 479                 }
 480                 state->dev = state->dev->next;
 481                 if (!state->dev) {
 482                         state->idev = NULL;
 483                         break;
 484                 }
 485                 state->idev = in6_dev_get(state->dev);
 486                 if (!state->idev)
 487                         continue;
 488                 read_lock_bh(&state->idev->lock);
 489                 im = state->idev->ac_list;
 490         }
 491         return im;
 492 }
 493
 494 static struct ifacaddr6 *ac6_get_idx(struct seq_file *seq, loff_t pos)
 495 {
 496         struct ifacaddr6 *im = ac6_get_first(seq);
 497         if (im)
 498                 while (pos && (im = ac6_get_next(seq, im)) != NULL)
 499                         --pos;
 500         return pos ? NULL : im;
 501 }
 502
 503 static void *ac6_seq_start(struct seq_file *seq, loff_t *pos)
 504 {
 505         read_lock(&dev_base_lock);
 506         return ac6_get_idx(seq, *pos);
 507 }
 508
 509 static void *ac6_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 510 {
 511         struct ifacaddr6 *im;
 512         im = ac6_get_next(seq, v);
 513         ++*pos;
 514         return im;
 515 }
 516
 517 static void ac6_seq_stop(struct seq_file *seq, void *v)
 518 {
 519         struct ac6_iter_state *state = ac6_seq_private(seq);
 520         if (likely(state->idev != NULL)) {
 521                 read_unlock_bh(&state->idev->lock);
 522                 in6_dev_put(state->idev);
 523         }
 524         read_unlock(&dev_base_lock);
 525 }
 526
 527 static int ac6_seq_show(struct seq_file *seq, void *v)
 528 {
 529         struct ifacaddr6 *im = (struct ifacaddr6 *)v;
 530         struct ac6_iter_state *state = ac6_seq_private(seq);
 531
 532         seq_printf(seq,
 533                    "%-4d %-15s " NIP6_SEQFMT " %5d\n",
 534                    state->dev->ifindex, state->dev->name,
 535                    NIP6(im->aca_addr),
 536                    im->aca_users);
 537         return 0;
 538 }
 539
 540 static struct seq_operations ac6_seq_ops = {
 541         .start  =       ac6_seq_start,
 542         .next   =       ac6_seq_next,
 543         .stop   =       ac6_seq_stop,
 544         .show   =       ac6_seq_show,
 545 };
 546
 547 static int ac6_seq_open(struct inode *inode, struct file *file)
 548 {
 549         struct seq_file *seq;
 550         int rc = -ENOMEM;
 551         struct ac6_iter_state *s = kzalloc(sizeof(*s), GFP_KERNEL);
 552
 553         if (!s)
 554                 goto out;
 555
 556         rc = seq_open(file, &ac6_seq_ops);
 557         if (rc)
 558                 goto out_kfree;
 559
 560         seq = file->private_data;
 561         seq->private = s;
 562 out:
 563         return rc;
 564 out_kfree:
 565         kfree(s);
 566         goto out;
 567 }
 568
 569 static struct file_operations ac6_seq_fops = {
 570         .owner          =       THIS_MODULE,
 571         .open           =       ac6_seq_open,
 572         .read           =       seq_read,
 573         .llseek         =       seq_lseek,
 574         .release        =       seq_release_private,
 575 };
 576
 577 int __init ac6_proc_init(void)
 578 {
 579         if (!proc_net_fops_create("anycast6", S_IRUGO, &ac6_seq_fops))
 580                 return -ENOMEM;
 581
 582         return 0;
 583 }
 584
 585 void ac6_proc_exit(void)
 586 {
 587         proc_net_remove("anycast6");
 588 }
 589 #endif
 590