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