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         unsigned int hash = inet6_acaddr_hash(net, addr);
 437         struct net_device *nh_dev;
 438         struct ifacaddr6 *aca;
 439         bool found = false;
 440
 441         rcu_read_lock();
 442         if (dev)
 443                 found = ipv6_chk_acast_dev(dev, addr);
 444         else
 445                 hlist_for_each_entry_rcu(aca, &inet6_acaddr_lst[hash],
 446                                          aca_addr_lst) {
 447                         nh_dev = fib6_info_nh_dev(aca->aca_rt);
 448                         if (!nh_dev || !net_eq(dev_net(nh_dev), net))
 449                                 continue;
 450                         if (ipv6_addr_equal(&aca->aca_addr, addr)) {
 451                                 found = true;
 452                                 break;
 453                         }
 454                 }
 455         rcu_read_unlock();
 456         return found;
 457 }
 458
 459 /*      check if this anycast address is link-local on given interface or
 460  *      is global
 461  */
 462 bool ipv6_chk_acast_addr_src(struct net *net, struct net_device *dev,
 463                              const struct in6_addr *addr)
 464 {
 465         return ipv6_chk_acast_addr(net,
 466                                    (ipv6_addr_type(addr) & IPV6_ADDR_LINKLOCAL ?
 467                                     dev : NULL),
 468                                    addr);
 469 }
 470
 471 #ifdef CONFIG_PROC_FS
 472 struct ac6_iter_state {
 473         struct seq_net_private p;
 474         struct net_device *dev;
 475         struct inet6_dev *idev;
 476 };
 477
 478 #define ac6_seq_private(seq)    ((struct ac6_iter_state *)(seq)->private)
 479
 480 static inline struct ifacaddr6 *ac6_get_first(struct seq_file *seq)
 481 {
 482         struct ifacaddr6 *im = NULL;
 483         struct ac6_iter_state *state = ac6_seq_private(seq);
 484         struct net *net = seq_file_net(seq);
 485
 486         state->idev = NULL;
 487         for_each_netdev_rcu(net, state->dev) {
 488                 struct inet6_dev *idev;
 489                 idev = __in6_dev_get(state->dev);
 490                 if (!idev)
 491                         continue;
 492                 read_lock_bh(&idev->lock);
 493                 im = idev->ac_list;
 494                 if (im) {
 495                         state->idev = idev;
 496                         break;
 497                 }
 498                 read_unlock_bh(&idev->lock);
 499         }
 500         return im;
 501 }
 502
 503 static struct ifacaddr6 *ac6_get_next(struct seq_file *seq, struct ifacaddr6 *im)
 504 {
 505         struct ac6_iter_state *state = ac6_seq_private(seq);
 506
 507         im = im->aca_next;
 508         while (!im) {
 509                 if (likely(state->idev != NULL))
 510                         read_unlock_bh(&state->idev->lock);
 511
 512                 state->dev = next_net_device_rcu(state->dev);
 513                 if (!state->dev) {
 514                         state->idev = NULL;
 515                         break;
 516                 }
 517                 state->idev = __in6_dev_get(state->dev);
 518                 if (!state->idev)
 519                         continue;
 520                 read_lock_bh(&state->idev->lock);
 521                 im = state->idev->ac_list;
 522         }
 523         return im;
 524 }
 525
 526 static struct ifacaddr6 *ac6_get_idx(struct seq_file *seq, loff_t pos)
 527 {
 528         struct ifacaddr6 *im = ac6_get_first(seq);
 529         if (im)
 530                 while (pos && (im = ac6_get_next(seq, im)) != NULL)
 531                         --pos;
 532         return pos ? NULL : im;
 533 }
 534
 535 static void *ac6_seq_start(struct seq_file *seq, loff_t *pos)
 536         __acquires(RCU)
 537 {
 538         rcu_read_lock();
 539         return ac6_get_idx(seq, *pos);
 540 }
 541
 542 static void *ac6_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 543 {
 544         struct ifacaddr6 *im = ac6_get_next(seq, v);
 545
 546         ++*pos;
 547         return im;
 548 }
 549
 550 static void ac6_seq_stop(struct seq_file *seq, void *v)
 551         __releases(RCU)
 552 {
 553         struct ac6_iter_state *state = ac6_seq_private(seq);
 554
 555         if (likely(state->idev != NULL)) {
 556                 read_unlock_bh(&state->idev->lock);
 557                 state->idev = NULL;
 558         }
 559         rcu_read_unlock();
 560 }
 561
 562 static int ac6_seq_show(struct seq_file *seq, void *v)
 563 {
 564         struct ifacaddr6 *im = (struct ifacaddr6 *)v;
 565         struct ac6_iter_state *state = ac6_seq_private(seq);
 566
 567         seq_printf(seq, "%-4d %-15s %pi6 %5d\n",
 568                    state->dev->ifindex, state->dev->name,
 569                    &im->aca_addr, im->aca_users);
 570         return 0;
 571 }
 572
 573 static const struct seq_operations ac6_seq_ops = {
 574         .start  =       ac6_seq_start,
 575         .next   =       ac6_seq_next,
 576         .stop   =       ac6_seq_stop,
 577         .show   =       ac6_seq_show,
 578 };
 579
 580 int __net_init ac6_proc_init(struct net *net)
 581 {
 582         if (!proc_create_net("anycast6", 0444, net->proc_net, &ac6_seq_ops,
 583                         sizeof(struct ac6_iter_state)))
 584                 return -ENOMEM;
 585
 586         return 0;
 587 }
 588
 589 void ac6_proc_exit(struct net *net)
 590 {
 591         remove_proc_entry("anycast6", net->proc_net);
 592 }
 593 #endif
 594
 595 /*      Init / cleanup code
 596  */
 597 int __init ipv6_anycast_init(void)
 598 {
 599         int i;
 600
 601         for (i = 0; i < IN6_ADDR_HSIZE; i++)
 602                 INIT_HLIST_HEAD(&inet6_acaddr_lst[i]);
 603         return 0;
 604 }
 605
 606 void ipv6_anycast_cleanup(void)
 607 {
 608         int i;
 609
 610         spin_lock(&acaddr_hash_lock);
 611         for (i = 0; i < IN6_ADDR_HSIZE; i++)
 612                 WARN_ON(!hlist_empty(&inet6_acaddr_lst[i]));
 613         spin_unlock(&acaddr_hash_lock);
 614 }