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