net/ipv6/anycast.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *      Anycast support for IPv6
   4  *      Linux INET6 implementation
   5  *
   6  *      Authors:
   7  *      David L Stevens (dlstevens@us.ibm.com)
   8  *
   9  *      based heavily on net/ipv6/mcast.c
  10  */
  11
  12 #include <linux/capability.h>
  13 #include <linux/module.h>
  14 #include <linux/errno.h>
  15 #include <linux/types.h>
  16 #include <linux/random.h>
  17 #include <linux/string.h>
  18 #include <linux/socket.h>
  19 #include <linux/sockios.h>
  20 #include <linux/net.h>
  21 #include <linux/in6.h>
  22 #include <linux/netdevice.h>
  23 #include <linux/if_arp.h>
  24 #include <linux/route.h>
  25 #include <linux/init.h>
  26 #include <linux/proc_fs.h>
  27 #include <linux/seq_file.h>
  28 #include <linux/slab.h>
  29
  30 #include <net/net_namespace.h>
  31 #include <net/sock.h>
  32 #include <net/snmp.h>
  33
  34 #include <net/ipv6.h>
  35 #include <net/protocol.h>
  36 #include <net/if_inet6.h>
  37 #include <net/ndisc.h>
  38 #include <net/addrconf.h>
  39 #include <net/ip6_route.h>
  40
  41 #include <net/checksum.h>
  42
  43 #define IN6_ADDR_HSIZE_SHIFT    8
  44 #define IN6_ADDR_HSIZE          BIT(IN6_ADDR_HSIZE_SHIFT)
  45 /*      anycast address hash table
  46  */
  47 static struct hlist_head inet6_acaddr_lst[IN6_ADDR_HSIZE];
  48 static DEFINE_SPINLOCK(acaddr_hash_lock);
  49
  50 static int ipv6_dev_ac_dec(struct net_device *dev, const struct in6_addr *addr);
  51
  52 static u32 inet6_acaddr_hash(struct net *net, const struct in6_addr *addr)
  53 {
  54         u32 val = ipv6_addr_hash(addr) ^ net_hash_mix(net);
  55
  56         return hash_32(val, IN6_ADDR_HSIZE_SHIFT);
  57 }
  58
  59 /*
  60  *      socket join an anycast group
  61  */
  62
  63 int ipv6_sock_ac_join(struct sock *sk, int ifindex, const struct in6_addr *addr)
  64 {
  65         struct ipv6_pinfo *np = inet6_sk(sk);
  66         struct net_device *dev = NULL;
  67         struct inet6_dev *idev;
  68         struct ipv6_ac_socklist *pac;
  69         struct net *net = sock_net(sk);
  70         int     ishost = !net->ipv6.devconf_all->forwarding;
  71         int     err = 0;
  72
  73         ASSERT_RTNL();
  74
  75         if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
  76                 return -EPERM;
  77         if (ipv6_addr_is_multicast(addr))
  78                 return -EINVAL;
  79
  80         if (ifindex)
  81                 dev = __dev_get_by_index(net, ifindex);
  82
  83         if (ipv6_chk_addr_and_flags(net, addr, dev, true, 0, IFA_F_TENTATIVE))
  84                 return -EINVAL;
  85
  86         pac = sock_kmalloc(sk, sizeof(struct ipv6_ac_socklist), GFP_KERNEL);
  87         if (!pac)
  88                 return -ENOMEM;
  89         pac->acl_next = NULL;
  90         pac->acl_addr = *addr;
  91
  92         if (ifindex == 0) {
  93                 struct rt6_info *rt;
  94
  95                 rt = rt6_lookup(net, addr, NULL, 0, NULL, 0);
  96                 if (rt) {
  97                         dev = rt->dst.dev;
  98                         ip6_rt_put(rt);
  99                 } else if (ishost) {
 100                         err = -EADDRNOTAVAIL;
 101                         goto error;
 102                 } else {
 103                         /* router, no matching interface: just pick one */
 104                         dev = __dev_get_by_flags(net, IFF_UP,
 105                                                  IFF_UP | IFF_LOOPBACK);
 106                 }
 107         }
 108
 109         if (!dev) {
 110                 err = -ENODEV;
 111                 goto error;
 112         }
 113
 114         idev = __in6_dev_get(dev);
 115         if (!idev) {
 116                 if (ifindex)
 117                         err = -ENODEV;
 118                 else
 119                         err = -EADDRNOTAVAIL;
 120                 goto error;
 121         }
 122         /* reset ishost, now that we have a specific device */
 123         ishost = !idev->cnf.forwarding;
 124
 125         pac->acl_ifindex = dev->ifindex;
 126
 127         /* XXX
 128          * For hosts, allow link-local or matching prefix anycasts.
 129          * This obviates the need for propagating anycast routes while
 130          * still allowing some non-router anycast participation.
 131          */
 132         if (!ipv6_chk_prefix(addr, dev)) {
 133                 if (ishost)
 134                         err = -EADDRNOTAVAIL;
 135                 if (err)
 136                         goto error;
 137         }
 138
 139         err = __ipv6_dev_ac_inc(idev, addr);
 140         if (!err) {
 141                 pac->acl_next = np->ipv6_ac_list;
 142                 np->ipv6_ac_list = pac;
 143                 pac = NULL;
 144         }
 145
 146 error:
 147         if (pac)
 148                 sock_kfree_s(sk, pac, sizeof(*pac));
 149         return err;
 150 }
 151
 152 /*
 153  *      socket leave an anycast group
 154  */
 155 int ipv6_sock_ac_drop(struct sock *sk, int ifindex, const struct in6_addr *addr)
 156 {
 157         struct ipv6_pinfo *np = inet6_sk(sk);
 158         struct net_device *dev;
 159         struct ipv6_ac_socklist *pac, *prev_pac;
 160         struct net *net = sock_net(sk);
 161
 162         ASSERT_RTNL();
 163
 164         prev_pac = NULL;
 165         for (pac = np->ipv6_ac_list; pac; pac = pac->acl_next) {
 166                 if ((ifindex == 0 || pac->acl_ifindex == ifindex) &&
 167                      ipv6_addr_equal(&pac->acl_addr, addr))
 168                         break;
 169                 prev_pac = pac;
 170         }
 171         if (!pac)
 172                 return -ENOENT;
 173         if (prev_pac)
 174                 prev_pac->acl_next = pac->acl_next;
 175         else
 176                 np->ipv6_ac_list = pac->acl_next;
 177
 178         dev = __dev_get_by_index(net, pac->acl_ifindex);
 179         if (dev)
 180                 ipv6_dev_ac_dec(dev, &pac->acl_addr);
 181
 182         sock_kfree_s(sk, pac, sizeof(*pac));
 183         return 0;
 184 }
 185
 186 void ipv6_sock_ac_close(struct sock *sk)
 187 {
 188         struct ipv6_pinfo *np = inet6_sk(sk);
 189         struct net_device *dev = NULL;
 190         struct ipv6_ac_socklist *pac;
 191         struct net *net = sock_net(sk);
 192         int     prev_index;
 193
 194         if (!np->ipv6_ac_list)
 195                 return;
 196
 197         rtnl_lock();
 198         pac = np->ipv6_ac_list;
 199         np->ipv6_ac_list = NULL;
 200
 201         prev_index = 0;
 202         while (pac) {
 203                 struct ipv6_ac_socklist *next = pac->acl_next;
 204
 205                 if (pac->acl_ifindex != prev_index) {
 206                         dev = __dev_get_by_index(net, pac->acl_ifindex);
 207                         prev_index = pac->acl_ifindex;
 208                 }
 209                 if (dev)
 210                         ipv6_dev_ac_dec(dev, &pac->acl_addr);
 211                 sock_kfree_s(sk, pac, sizeof(*pac));
 212                 pac = next;
 213         }
 214         rtnl_unlock();
 215 }
 216
 217 static void ipv6_add_acaddr_hash(struct net *net, struct ifacaddr6 *aca)
 218 {
 219         unsigned int hash = inet6_acaddr_hash(net, &aca->aca_addr);
 220
 221         spin_lock(&acaddr_hash_lock);
 222         hlist_add_head_rcu(&aca->aca_addr_lst, &inet6_acaddr_lst[hash]);
 223         spin_unlock(&acaddr_hash_lock);
 224 }
 225
 226 static void ipv6_del_acaddr_hash(struct ifacaddr6 *aca)
 227 {
 228         spin_lock(&acaddr_hash_lock);
 229         hlist_del_init_rcu(&aca->aca_addr_lst);
 230         spin_unlock(&acaddr_hash_lock);
 231 }
 232
 233 static void aca_get(struct ifacaddr6 *aca)
 234 {
 235         refcount_inc(&aca->aca_refcnt);
 236 }
 237
 238 static void aca_free_rcu(struct rcu_head *h)
 239 {
 240         struct ifacaddr6 *aca = container_of(h, struct ifacaddr6, rcu);
 241
 242         fib6_info_release(aca->aca_rt);
 243         kfree(aca);
 244 }
 245
 246 static void aca_put(struct ifacaddr6 *ac)
 247 {
 248         if (refcount_dec_and_test(&ac->aca_refcnt)) {
 249                 call_rcu(&ac->rcu, aca_free_rcu);
 250         }
 251 }
 252
 253 static struct ifacaddr6 *aca_alloc(struct fib6_info *f6i,
 254                                    const struct in6_addr *addr)
 255 {
 256         struct ifacaddr6 *aca;
 257
 258         aca = kzalloc(sizeof(*aca), GFP_ATOMIC);
 259         if (!aca)
 260                 return NULL;
 261
 262         aca->aca_addr = *addr;
 263         fib6_info_hold(f6i);
 264         aca->aca_rt = f6i;
 265         INIT_HLIST_NODE(&aca->aca_addr_lst);
 266         aca->aca_users = 1;
 267         /* aca_tstamp should be updated upon changes */
 268         aca->aca_cstamp = aca->aca_tstamp = jiffies;
 269         refcount_set(&aca->aca_refcnt, 1);
 270
 271         return aca;
 272 }
 273
 274 /*
 275  *      device anycast group inc (add if not found)
 276  */
 277 int __ipv6_dev_ac_inc(struct inet6_dev *idev, const struct in6_addr *addr)
 278 {
 279         struct ifacaddr6 *aca;
 280         struct fib6_info *f6i;
 281         struct net *net;
 282         int err;
 283
 284         ASSERT_RTNL();
 285
 286         write_lock_bh(&idev->lock);
 287         if (idev->dead) {
 288                 err = -ENODEV;
 289                 goto out;
 290         }
 291
 292         for (aca = idev->ac_list; aca; aca = aca->aca_next) {
 293                 if (ipv6_addr_equal(&aca->aca_addr, addr)) {
 294                         aca->aca_users++;
 295                         err = 0;
 296                         goto out;
 297                 }
 298         }
 299
 300         net = dev_net(idev->dev);
 301         f6i = addrconf_f6i_alloc(net, idev, addr, true, GFP_ATOMIC);
 302         if (IS_ERR(f6i)) {
 303                 err = PTR_ERR(f6i);
 304                 goto out;
 305         }
 306         aca = aca_alloc(f6i, addr);
 307         if (!aca) {
 308                 fib6_info_release(f6i);
 309                 err = -ENOMEM;
 310                 goto out;
 311         }
 312
 313         aca->aca_next = idev->ac_list;
 314         idev->ac_list = aca;
 315
 316         /* Hold this for addrconf_join_solict() below before we unlock,
 317          * it is already exposed via idev->ac_list.
 318          */
 319         aca_get(aca);
 320         write_unlock_bh(&idev->lock);
 321
 322         ipv6_add_acaddr_hash(net, aca);
 323
 324         ip6_ins_rt(net, f6i);
 325
 326         addrconf_join_solict(idev->dev, &aca->aca_addr);
 327
 328         aca_put(aca);
 329         return 0;
 330 out:
 331         write_unlock_bh(&idev->lock);
 332         return err;
 333 }
 334
 335 /*
 336  *      device anycast group decrement
 337  */
 338 int __ipv6_dev_ac_dec(struct inet6_dev *idev, const struct in6_addr *addr)
 339 {
 340         struct ifacaddr6 *aca, *prev_aca;
 341
 342         ASSERT_RTNL();
 343
 344         write_lock_bh(&idev->lock);
 345         prev_aca = NULL;
 346         for (aca = idev->ac_list; aca; aca = aca->aca_next) {
 347                 if (ipv6_addr_equal(&aca->aca_addr, addr))
 348                         break;
 349                 prev_aca = aca;
 350         }
 351         if (!aca) {
 352                 write_unlock_bh(&idev->lock);
 353                 return -ENOENT;
 354         }
 355         if (--aca->aca_users > 0) {
 356                 write_unlock_bh(&idev->lock);
 357                 return 0;
 358         }
 359         if (prev_aca)
 360                 prev_aca->aca_next = aca->aca_next;
 361         else
 362                 idev->ac_list = aca->aca_next;
 363         write_unlock_bh(&idev->lock);
 364         ipv6_del_acaddr_hash(aca);
 365         addrconf_leave_solict(idev, &aca->aca_addr);
 366
 367         ip6_del_rt(dev_net(idev->dev), aca->aca_rt, false);
 368
 369         aca_put(aca);
 370         return 0;
 371 }
 372
 373 /* called with rtnl_lock() */
 374 static int ipv6_dev_ac_dec(struct net_device *dev, const struct in6_addr *addr)
 375 {
 376         struct inet6_dev *idev = __in6_dev_get(dev);
 377
 378         if (!idev)
 379                 return -ENODEV;
 380         return __ipv6_dev_ac_dec(idev, addr);
 381 }
 382
 383 void ipv6_ac_destroy_dev(struct inet6_dev *idev)
 384 {
 385         struct ifacaddr6 *aca;
 386
 387         write_lock_bh(&idev->lock);
 388         while ((aca = idev->ac_list) != NULL) {
 389                 idev->ac_list = aca->aca_next;
 390                 write_unlock_bh(&idev->lock);
 391
 392                 ipv6_del_acaddr_hash(aca);
 393
 394                 addrconf_leave_solict(idev, &aca->aca_addr);
 395
 396                 ip6_del_rt(dev_net(idev->dev), aca->aca_rt, false);
 397
 398                 aca_put(aca);
 399
 400                 write_lock_bh(&idev->lock);
 401         }
 402         write_unlock_bh(&idev->lock);
 403 }
 404
 405 /*
 406  *      check if the interface has this anycast address
 407  *      called with rcu_read_lock()
 408  */
 409 static bool ipv6_chk_acast_dev(struct net_device *dev, const struct in6_addr *addr)
 410 {
 411         struct inet6_dev *idev;
 412         struct ifacaddr6 *aca;
 413
 414         idev = __in6_dev_get(dev);
 415         if (idev) {
 416                 read_lock_bh(&idev->lock);
 417                 for (aca = idev->ac_list; aca; aca = aca->aca_next)
 418                         if (ipv6_addr_equal(&aca->aca_addr, addr))
 419                                 break;
 420                 read_unlock_bh(&idev->lock);
 421                 return aca != NULL;
 422         }
 423         return false;
 424 }
 425
 426 /*
 427  *      check if given interface (or any, if dev==0) has this anycast address
 428  */
 429 bool ipv6_chk_acast_addr(struct net *net, struct net_device *dev,
 430                          const struct in6_addr *addr)
 431 {
 432         struct net_device *nh_dev;
 433         struct ifacaddr6 *aca;
 434         bool found = false;
 435
 436         rcu_read_lock();
 437         if (dev)
 438                 found = ipv6_chk_acast_dev(dev, addr);
 439         else {
 440                 unsigned int hash = inet6_acaddr_hash(net, addr);
 441
 442                 hlist_for_each_entry_rcu(aca, &inet6_acaddr_lst[hash],
 443                                          aca_addr_lst) {
 444                         nh_dev = fib6_info_nh_dev(aca->aca_rt);
 445                         if (!nh_dev || !net_eq(dev_net(nh_dev), net))
 446                                 continue;
 447                         if (ipv6_addr_equal(&aca->aca_addr, addr)) {
 448                                 found = true;
 449                                 break;
 450                         }
 451                 }
 452         }
 453         rcu_read_unlock();
 454         return found;
 455 }
 456
 457 /*      check if this anycast address is link-local on given interface or
 458  *      is global
 459  */
 460 bool ipv6_chk_acast_addr_src(struct net *net, struct net_device *dev,
 461                              const struct in6_addr *addr)
 462 {
 463         return ipv6_chk_acast_addr(net,
 464                                    (ipv6_addr_type(addr) & IPV6_ADDR_LINKLOCAL ?
 465                                     dev : NULL),
 466                                    addr);
 467 }
 468
 469 #ifdef CONFIG_PROC_FS
 470 struct ac6_iter_state {
 471         struct seq_net_private p;
 472         struct net_device *dev;
 473         struct inet6_dev *idev;
 474 };
 475
 476 #define ac6_seq_private(seq)    ((struct ac6_iter_state *)(seq)->private)
 477
 478 static inline struct ifacaddr6 *ac6_get_first(struct seq_file *seq)
 479 {
 480         struct ifacaddr6 *im = NULL;
 481         struct ac6_iter_state *state = ac6_seq_private(seq);
 482         struct net *net = seq_file_net(seq);
 483
 484         state->idev = NULL;
 485         for_each_netdev_rcu(net, state->dev) {
 486                 struct inet6_dev *idev;
 487                 idev = __in6_dev_get(state->dev);
 488                 if (!idev)
 489                         continue;
 490                 read_lock_bh(&idev->lock);
 491                 im = idev->ac_list;
 492                 if (im) {
 493                         state->idev = idev;
 494                         break;
 495                 }
 496                 read_unlock_bh(&idev->lock);
 497         }
 498         return im;
 499 }
 500
 501 static struct ifacaddr6 *ac6_get_next(struct seq_file *seq, struct ifacaddr6 *im)
 502 {
 503         struct ac6_iter_state *state = ac6_seq_private(seq);
 504
 505         im = im->aca_next;
 506         while (!im) {
 507                 if (likely(state->idev != NULL))
 508                         read_unlock_bh(&state->idev->lock);
 509
 510                 state->dev = next_net_device_rcu(state->dev);
 511                 if (!state->dev) {
 512                         state->idev = NULL;
 513                         break;
 514                 }
 515                 state->idev = __in6_dev_get(state->dev);
 516                 if (!state->idev)
 517                         continue;
 518                 read_lock_bh(&state->idev->lock);
 519                 im = state->idev->ac_list;
 520         }
 521         return im;
 522 }
 523
 524 static struct ifacaddr6 *ac6_get_idx(struct seq_file *seq, loff_t pos)
 525 {
 526         struct ifacaddr6 *im = ac6_get_first(seq);
 527         if (im)
 528                 while (pos && (im = ac6_get_next(seq, im)) != NULL)
 529                         --pos;
 530         return pos ? NULL : im;
 531 }
 532
 533 static void *ac6_seq_start(struct seq_file *seq, loff_t *pos)
 534         __acquires(RCU)
 535 {
 536         rcu_read_lock();
 537         return ac6_get_idx(seq, *pos);
 538 }
 539
 540 static void *ac6_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 541 {
 542         struct ifacaddr6 *im = ac6_get_next(seq, v);
 543
 544         ++*pos;
 545         return im;
 546 }
 547
 548 static void ac6_seq_stop(struct seq_file *seq, void *v)
 549         __releases(RCU)
 550 {
 551         struct ac6_iter_state *state = ac6_seq_private(seq);
 552
 553         if (likely(state->idev != NULL)) {
 554                 read_unlock_bh(&state->idev->lock);
 555                 state->idev = NULL;
 556         }
 557         rcu_read_unlock();
 558 }
 559
 560 static int ac6_seq_show(struct seq_file *seq, void *v)
 561 {
 562         struct ifacaddr6 *im = (struct ifacaddr6 *)v;
 563         struct ac6_iter_state *state = ac6_seq_private(seq);
 564
 565         seq_printf(seq, "%-4d %-15s %pi6 %5d\n",
 566                    state->dev->ifindex, state->dev->name,
 567                    &im->aca_addr, im->aca_users);
 568         return 0;
 569 }
 570
 571 static const struct seq_operations ac6_seq_ops = {
 572         .start  =       ac6_seq_start,
 573         .next   =       ac6_seq_next,
 574         .stop   =       ac6_seq_stop,
 575         .show   =       ac6_seq_show,
 576 };
 577
 578 int __net_init ac6_proc_init(struct net *net)
 579 {
 580         if (!proc_create_net("anycast6", 0444, net->proc_net, &ac6_seq_ops,
 581                         sizeof(struct ac6_iter_state)))
 582                 return -ENOMEM;
 583
 584         return 0;
 585 }
 586
 587 void ac6_proc_exit(struct net *net)
 588 {
 589         remove_proc_entry("anycast6", net->proc_net);
 590 }
 591 #endif
 592
 593 /*      Init / cleanup code
 594  */
 595 int __init ipv6_anycast_init(void)
 596 {
 597         int i;
 598
 599         for (i = 0; i < IN6_ADDR_HSIZE; i++)
 600                 INIT_HLIST_HEAD(&inet6_acaddr_lst[i]);
 601         return 0;
 602 }
 603
 604 void ipv6_anycast_cleanup(void)
 605 {
 606         int i;
 607
 608         spin_lock(&acaddr_hash_lock);
 609         for (i = 0; i < IN6_ADDR_HSIZE; i++)
 610                 WARN_ON(!hlist_empty(&inet6_acaddr_lst[i]));
 611         spin_unlock(&acaddr_hash_lock);
 612 }