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 #include <linux/slab.h>
  33
  34 #include <net/net_namespace.h>
  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 #define IN6_ADDR_HSIZE_SHIFT    8
  48 #define IN6_ADDR_HSIZE          BIT(IN6_ADDR_HSIZE_SHIFT)
  49 /*      anycast address hash table
  50  */
  51 static struct hlist_head inet6_acaddr_lst[IN6_ADDR_HSIZE];
  52 static DEFINE_SPINLOCK(acaddr_hash_lock);
  53
  54 static int ipv6_dev_ac_dec(struct net_device *dev, const struct in6_addr *addr);
  55
  56 static u32 inet6_acaddr_hash(struct net *net, const struct in6_addr *addr)
  57 {
  58         u32 val = ipv6_addr_hash(addr) ^ net_hash_mix(net);
  59
  60         return hash_32(val, IN6_ADDR_HSIZE_SHIFT);
  61 }
  62
  63 /*
  64  *      socket join an anycast group
  65  */
  66
  67 int ipv6_sock_ac_join(struct sock *sk, int ifindex, const struct in6_addr *addr)
  68 {
  69         struct ipv6_pinfo *np = inet6_sk(sk);
  70         struct net_device *dev = NULL;
  71         struct inet6_dev *idev;
  72         struct ipv6_ac_socklist *pac;
  73         struct net *net = sock_net(sk);
  74         int     ishost = !net->ipv6.devconf_all->forwarding;
  75         int     err = 0;
  76
  77         ASSERT_RTNL();
  78
  79         if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
  80                 return -EPERM;
  81         if (ipv6_addr_is_multicast(addr))
  82                 return -EINVAL;
  83
  84         if (ifindex)
  85                 dev = __dev_get_by_index(net, ifindex);
  86
  87         if (ipv6_chk_addr_and_flags(net, addr, dev, true, 0, IFA_F_TENTATIVE))
  88                 return -EINVAL;
  89
  90         pac = sock_kmalloc(sk, sizeof(struct ipv6_ac_socklist), GFP_KERNEL);
  91         if (!pac)
  92                 return -ENOMEM;
  93         pac->acl_next = NULL;
  94         pac->acl_addr = *addr;
  95
  96         if (ifindex == 0) {
  97                 struct rt6_info *rt;
  98
  99                 rt = rt6_lookup(net, addr, NULL, 0, NULL, 0);
 100                 if (rt) {
 101                         dev = rt->dst.dev;
 102                         ip6_rt_put(rt);
 103                 } else if (ishost) {
 104                         err = -EADDRNOTAVAIL;
 105                         goto error;
 106                 } else {
 107                         /* router, no matching interface: just pick one */
 108                         dev = __dev_get_by_flags(net, IFF_UP,
 109                                                  IFF_UP | IFF_LOOPBACK);
 110                 }
 111         }
 112
 113         if (!dev) {
 114                 err = -ENODEV;
 115                 goto error;
 116         }
 117
 118         idev = __in6_dev_get(dev);
 119         if (!idev) {
 120                 if (ifindex)
 121                         err = -ENODEV;
 122                 else
 123                         err = -EADDRNOTAVAIL;
 124                 goto error;
 125         }
 126         /* reset ishost, now that we have a specific device */
 127         ishost = !idev->cnf.forwarding;
 128
 129         pac->acl_ifindex = dev->ifindex;
 130
 131         /* XXX
 132          * For hosts, allow link-local or matching prefix anycasts.
 133          * This obviates the need for propagating anycast routes while
 134          * still allowing some non-router anycast participation.
 135          */
 136         if (!ipv6_chk_prefix(addr, dev)) {
 137                 if (ishost)
 138                         err = -EADDRNOTAVAIL;
 139                 if (err)
 140                         goto error;
 141         }
 142
 143         err = __ipv6_dev_ac_inc(idev, addr);
 144         if (!err) {
 145                 pac->acl_next = np->ipv6_ac_list;
 146                 np->ipv6_ac_list = pac;
 147                 pac = NULL;
 148         }
 149
 150 error:
 151         if (pac)
 152                 sock_kfree_s(sk, pac, sizeof(*pac));
 153         return err;
 154 }
 155
 156 /*
 157  *      socket leave an anycast group
 158  */
 159 int ipv6_sock_ac_drop(struct sock *sk, int ifindex, const struct in6_addr *addr)
 160 {
 161         struct ipv6_pinfo *np = inet6_sk(sk);
 162         struct net_device *dev;
 163         struct ipv6_ac_socklist *pac, *prev_pac;
 164         struct net *net = sock_net(sk);
 165
 166         ASSERT_RTNL();
 167
 168         prev_pac = NULL;
 169         for (pac = np->ipv6_ac_list; pac; pac = pac->acl_next) {
 170                 if ((ifindex == 0 || pac->acl_ifindex == ifindex) &&
 171                      ipv6_addr_equal(&pac->acl_addr, addr))
 172                         break;
 173                 prev_pac = pac;
 174         }
 175         if (!pac)
 176                 return -ENOENT;
 177         if (prev_pac)
 178                 prev_pac->acl_next = pac->acl_next;
 179         else
 180                 np->ipv6_ac_list = pac->acl_next;
 181
 182         dev = __dev_get_by_index(net, pac->acl_ifindex);
 183         if (dev)
 184                 ipv6_dev_ac_dec(dev, &pac->acl_addr);
 185
 186         sock_kfree_s(sk, pac, sizeof(*pac));
 187         return 0;
 188 }
 189
 190 void ipv6_sock_ac_close(struct sock *sk)
 191 {
 192         struct ipv6_pinfo *np = inet6_sk(sk);
 193         struct net_device *dev = NULL;
 194         struct ipv6_ac_socklist *pac;
 195         struct net *net = sock_net(sk);
 196         int     prev_index;
 197
 198         if (!np->ipv6_ac_list)
 199                 return;
 200
 201         rtnl_lock();
 202         pac = np->ipv6_ac_list;
 203         np->ipv6_ac_list = NULL;
 204
 205         prev_index = 0;
 206         while (pac) {
 207                 struct ipv6_ac_socklist *next = pac->acl_next;
 208
 209                 if (pac->acl_ifindex != prev_index) {
 210                         dev = __dev_get_by_index(net, pac->acl_ifindex);
 211                         prev_index = pac->acl_ifindex;
 212                 }
 213                 if (dev)
 214                         ipv6_dev_ac_dec(dev, &pac->acl_addr);
 215                 sock_kfree_s(sk, pac, sizeof(*pac));
 216                 pac = next;
 217         }
 218         rtnl_unlock();
 219 }
 220
 221 static void ipv6_add_acaddr_hash(struct net *net, struct ifacaddr6 *aca)
 222 {
 223         unsigned int hash = inet6_acaddr_hash(net, &aca->aca_addr);
 224
 225         spin_lock(&acaddr_hash_lock);
 226         hlist_add_head_rcu(&aca->aca_addr_lst, &inet6_acaddr_lst[hash]);
 227         spin_unlock(&acaddr_hash_lock);
 228 }
 229
 230 static void ipv6_del_acaddr_hash(struct ifacaddr6 *aca)
 231 {
 232         spin_lock(&acaddr_hash_lock);
 233         hlist_del_init_rcu(&aca->aca_addr_lst);
 234         spin_unlock(&acaddr_hash_lock);
 235 }
 236
 237 static void aca_get(struct ifacaddr6 *aca)
 238 {
 239         refcount_inc(&aca->aca_refcnt);
 240 }
 241
 242 static void aca_free_rcu(struct rcu_head *h)
 243 {
 244         struct ifacaddr6 *aca = container_of(h, struct ifacaddr6, rcu);
 245
 246         fib6_info_release(aca->aca_rt);
 247         kfree(aca);
 248 }
 249
 250 static void aca_put(struct ifacaddr6 *ac)
 251 {
 252         if (refcount_dec_and_test(&ac->aca_refcnt)) {
 253                 call_rcu(&ac->rcu, aca_free_rcu);
 254         }
 255 }
 256
 257 static struct ifacaddr6 *aca_alloc(struct fib6_info *f6i,
 258                                    const struct in6_addr *addr)
 259 {
 260         struct ifacaddr6 *aca;
 261
 262         aca = kzalloc(sizeof(*aca), GFP_ATOMIC);
 263         if (!aca)
 264                 return NULL;
 265
 266         aca->aca_addr = *addr;
 267         fib6_info_hold(f6i);
 268         aca->aca_rt = f6i;
 269         INIT_HLIST_NODE(&aca->aca_addr_lst);
 270         aca->aca_users = 1;
 271         /* aca_tstamp should be updated upon changes */
 272         aca->aca_cstamp = aca->aca_tstamp = jiffies;
 273         refcount_set(&aca->aca_refcnt, 1);
 274
 275         return aca;
 276 }
 277
 278 /*
 279  *      device anycast group inc (add if not found)
 280  */
 281 int __ipv6_dev_ac_inc(struct inet6_dev *idev, const struct in6_addr *addr)
 282 {
 283         struct ifacaddr6 *aca;
 284         struct fib6_info *f6i;
 285         struct net *net;
 286         int err;
 287
 288         ASSERT_RTNL();
 289
 290         write_lock_bh(&idev->lock);
 291         if (idev->dead) {
 292                 err = -ENODEV;
 293                 goto out;
 294         }
 295
 296         for (aca = idev->ac_list; aca; aca = aca->aca_next) {
 297                 if (ipv6_addr_equal(&aca->aca_addr, addr)) {
 298                         aca->aca_users++;
 299                         err = 0;
 300                         goto out;
 301                 }
 302         }
 303
 304         net = dev_net(idev->dev);
 305         f6i = addrconf_f6i_alloc(net, idev, addr, true, GFP_ATOMIC);
 306         if (IS_ERR(f6i)) {
 307                 err = PTR_ERR(f6i);
 308                 goto out;
 309         }
 310         aca = aca_alloc(f6i, addr);
 311         if (!aca) {
 312                 fib6_info_release(f6i);
 313                 err = -ENOMEM;
 314                 goto out;
 315         }
 316
 317         aca->aca_next = idev->ac_list;
 318         idev->ac_list = aca;
 319
 320         /* Hold this for addrconf_join_solict() below before we unlock,
 321          * it is already exposed via idev->ac_list.
 322          */
 323         aca_get(aca);
 324         write_unlock_bh(&idev->lock);
 325
 326         ipv6_add_acaddr_hash(net, aca);
 327
 328         ip6_ins_rt(net, f6i);
 329
 330         addrconf_join_solict(idev->dev, &aca->aca_addr);
 331
 332         aca_put(aca);
 333         return 0;
 334 out:
 335         write_unlock_bh(&idev->lock);
 336         return err;
 337 }
 338
 339 /*
 340  *      device anycast group decrement
 341  */
 342 int __ipv6_dev_ac_dec(struct inet6_dev *idev, const struct in6_addr *addr)
 343 {
 344         struct ifacaddr6 *aca, *prev_aca;
 345
 346         ASSERT_RTNL();
 347
 348         write_lock_bh(&idev->lock);
 349         prev_aca = NULL;
 350         for (aca = idev->ac_list; aca; aca = aca->aca_next) {
 351                 if (ipv6_addr_equal(&aca->aca_addr, addr))
 352                         break;
 353                 prev_aca = aca;
 354         }
 355         if (!aca) {
 356                 write_unlock_bh(&idev->lock);
 357                 return -ENOENT;
 358         }
 359         if (--aca->aca_users > 0) {
 360                 write_unlock_bh(&idev->lock);
 361                 return 0;
 362         }
 363         if (prev_aca)
 364                 prev_aca->aca_next = aca->aca_next;
 365         else
 366                 idev->ac_list = aca->aca_next;
 367         write_unlock_bh(&idev->lock);
 368         ipv6_del_acaddr_hash(aca);
 369         addrconf_leave_solict(idev, &aca->aca_addr);
 370
 371         ip6_del_rt(dev_net(idev->dev), aca->aca_rt);
 372
 373         aca_put(aca);
 374         return 0;
 375 }
 376
 377 /* called with rtnl_lock() */
 378 static int ipv6_dev_ac_dec(struct net_device *dev, const struct in6_addr *addr)
 379 {
 380         struct inet6_dev *idev = __in6_dev_get(dev);
 381
 382         if (!idev)
 383                 return -ENODEV;
 384         return __ipv6_dev_ac_dec(idev, addr);
 385 }
 386
 387 void ipv6_ac_destroy_dev(struct inet6_dev *idev)
 388 {
 389         struct ifacaddr6 *aca;
 390
 391         write_lock_bh(&idev->lock);
 392         while ((aca = idev->ac_list) != NULL) {
 393                 idev->ac_list = aca->aca_next;
 394                 write_unlock_bh(&idev->lock);
 395
 396                 ipv6_del_acaddr_hash(aca);
 397
 398                 addrconf_leave_solict(idev, &aca->aca_addr);
 399
 400                 ip6_del_rt(dev_net(idev->dev), aca->aca_rt);
 401
 402                 aca_put(aca);
 403
 404                 write_lock_bh(&idev->lock);
 405         }
 406         write_unlock_bh(&idev->lock);
 407 }
 408
 409 /*
 410  *      check if the interface has this anycast address
 411  *      called with rcu_read_lock()
 412  */
 413 static bool ipv6_chk_acast_dev(struct net_device *dev, const struct in6_addr *addr)
 414 {
 415         struct inet6_dev *idev;
 416         struct ifacaddr6 *aca;
 417
 418         idev = __in6_dev_get(dev);
 419         if (idev) {
 420                 read_lock_bh(&idev->lock);
 421                 for (aca = idev->ac_list; aca; aca = aca->aca_next)
 422                         if (ipv6_addr_equal(&aca->aca_addr, addr))
 423                                 break;
 424                 read_unlock_bh(&idev->lock);
 425                 return aca != NULL;
 426         }
 427         return false;
 428 }
 429
 430 /*
 431  *      check if given interface (or any, if dev==0) has this anycast address
 432  */
 433 bool ipv6_chk_acast_addr(struct net *net, struct net_device *dev,
 434                          const struct in6_addr *addr)
 435 {
 436         struct net_device *nh_dev;
 437         struct ifacaddr6 *aca;
 438         bool found = false;
 439
 440         rcu_read_lock();
 441         if (dev)
 442                 found = ipv6_chk_acast_dev(dev, addr);
 443         else {
 444                 unsigned int hash = inet6_acaddr_hash(net, addr);
 445
 446                 hlist_for_each_entry_rcu(aca, &inet6_acaddr_lst[hash],
 447                                          aca_addr_lst) {
 448                         nh_dev = fib6_info_nh_dev(aca->aca_rt);
 449                         if (!nh_dev || !net_eq(dev_net(nh_dev), net))
 450                                 continue;
 451                         if (ipv6_addr_equal(&aca->aca_addr, addr)) {
 452                                 found = true;
 453                                 break;
 454                         }
 455                 }
 456         }
 457         rcu_read_unlock();
 458         return found;
 459 }
 460
 461 /*      check if this anycast address is link-local on given interface or
 462  *      is global
 463  */
 464 bool ipv6_chk_acast_addr_src(struct net *net, struct net_device *dev,
 465                              const struct in6_addr *addr)
 466 {
 467         return ipv6_chk_acast_addr(net,
 468                                    (ipv6_addr_type(addr) & IPV6_ADDR_LINKLOCAL ?
 469                                     dev : NULL),
 470                                    addr);
 471 }
 472
 473 #ifdef CONFIG_PROC_FS
 474 struct ac6_iter_state {
 475         struct seq_net_private p;
 476         struct net_device *dev;
 477         struct inet6_dev *idev;
 478 };
 479
 480 #define ac6_seq_private(seq)    ((struct ac6_iter_state *)(seq)->private)
 481
 482 static inline struct ifacaddr6 *ac6_get_first(struct seq_file *seq)
 483 {
 484         struct ifacaddr6 *im = NULL;
 485         struct ac6_iter_state *state = ac6_seq_private(seq);
 486         struct net *net = seq_file_net(seq);
 487
 488         state->idev = NULL;
 489         for_each_netdev_rcu(net, state->dev) {
 490                 struct inet6_dev *idev;
 491                 idev = __in6_dev_get(state->dev);
 492                 if (!idev)
 493                         continue;
 494                 read_lock_bh(&idev->lock);
 495                 im = idev->ac_list;
 496                 if (im) {
 497                         state->idev = idev;
 498                         break;
 499                 }
 500                 read_unlock_bh(&idev->lock);
 501         }
 502         return im;
 503 }
 504
 505 static struct ifacaddr6 *ac6_get_next(struct seq_file *seq, struct ifacaddr6 *im)
 506 {
 507         struct ac6_iter_state *state = ac6_seq_private(seq);
 508
 509         im = im->aca_next;
 510         while (!im) {
 511                 if (likely(state->idev != NULL))
 512                         read_unlock_bh(&state->idev->lock);
 513
 514                 state->dev = next_net_device_rcu(state->dev);
 515                 if (!state->dev) {
 516                         state->idev = NULL;
 517                         break;
 518                 }
 519                 state->idev = __in6_dev_get(state->dev);
 520                 if (!state->idev)
 521                         continue;
 522                 read_lock_bh(&state->idev->lock);
 523                 im = state->idev->ac_list;
 524         }
 525         return im;
 526 }
 527
 528 static struct ifacaddr6 *ac6_get_idx(struct seq_file *seq, loff_t pos)
 529 {
 530         struct ifacaddr6 *im = ac6_get_first(seq);
 531         if (im)
 532                 while (pos && (im = ac6_get_next(seq, im)) != NULL)
 533                         --pos;
 534         return pos ? NULL : im;
 535 }
 536
 537 static void *ac6_seq_start(struct seq_file *seq, loff_t *pos)
 538         __acquires(RCU)
 539 {
 540         rcu_read_lock();
 541         return ac6_get_idx(seq, *pos);
 542 }
 543
 544 static void *ac6_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 545 {
 546         struct ifacaddr6 *im = ac6_get_next(seq, v);
 547
 548         ++*pos;
 549         return im;
 550 }
 551
 552 static void ac6_seq_stop(struct seq_file *seq, void *v)
 553         __releases(RCU)
 554 {
 555         struct ac6_iter_state *state = ac6_seq_private(seq);
 556
 557         if (likely(state->idev != NULL)) {
 558                 read_unlock_bh(&state->idev->lock);
 559                 state->idev = NULL;
 560         }
 561         rcu_read_unlock();
 562 }
 563
 564 static int ac6_seq_show(struct seq_file *seq, void *v)
 565 {
 566         struct ifacaddr6 *im = (struct ifacaddr6 *)v;
 567         struct ac6_iter_state *state = ac6_seq_private(seq);
 568
 569         seq_printf(seq, "%-4d %-15s %pi6 %5d\n",
 570                    state->dev->ifindex, state->dev->name,
 571                    &im->aca_addr, im->aca_users);
 572         return 0;
 573 }
 574
 575 static const struct seq_operations ac6_seq_ops = {
 576         .start  =       ac6_seq_start,
 577         .next   =       ac6_seq_next,
 578         .stop   =       ac6_seq_stop,
 579         .show   =       ac6_seq_show,
 580 };
 581
 582 int __net_init ac6_proc_init(struct net *net)
 583 {
 584         if (!proc_create_net("anycast6", 0444, net->proc_net, &ac6_seq_ops,
 585                         sizeof(struct ac6_iter_state)))
 586                 return -ENOMEM;
 587
 588         return 0;
 589 }
 590
 591 void ac6_proc_exit(struct net *net)
 592 {
 593         remove_proc_entry("anycast6", net->proc_net);
 594 }
 595 #endif
 596
 597 /*      Init / cleanup code
 598  */
 599 int __init ipv6_anycast_init(void)
 600 {
 601         int i;
 602
 603         for (i = 0; i < IN6_ADDR_HSIZE; i++)
 604                 INIT_HLIST_HEAD(&inet6_acaddr_lst[i]);
 605         return 0;
 606 }
 607
 608 void ipv6_anycast_cleanup(void)
 609 {
 610         int i;
 611
 612         spin_lock(&acaddr_hash_lock);
 613         for (i = 0; i < IN6_ADDR_HSIZE; i++)
 614                 WARN_ON(!hlist_empty(&inet6_acaddr_lst[i]));
 615         spin_unlock(&acaddr_hash_lock);
 616 }