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 static int ipv6_dev_ac_dec(struct net_device *dev, const struct in6_addr *addr);
  48
  49 /* Big ac list lock for all the sockets */
  50 static DEFINE_SPINLOCK(ipv6_sk_ac_lock);
  51
  52
  53 /*
  54  *      socket join an anycast group
  55  */
  56
  57 int ipv6_sock_ac_join(struct sock *sk, int ifindex, const struct in6_addr *addr)
  58 {
  59         struct ipv6_pinfo *np = inet6_sk(sk);
  60         struct net_device *dev = NULL;
  61         struct inet6_dev *idev;
  62         struct ipv6_ac_socklist *pac;
  63         struct net *net = sock_net(sk);
  64         int     ishost = !net->ipv6.devconf_all->forwarding;
  65         int     err = 0;
  66
  67         if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
  68                 return -EPERM;
  69         if (ipv6_addr_is_multicast(addr))
  70                 return -EINVAL;
  71         if (ipv6_chk_addr(net, addr, NULL, 0))
  72                 return -EINVAL;
  73
  74         pac = sock_kmalloc(sk, sizeof(struct ipv6_ac_socklist), GFP_KERNEL);
  75         if (pac == NULL)
  76                 return -ENOMEM;
  77         pac->acl_next = NULL;
  78         pac->acl_addr = *addr;
  79
  80         rtnl_lock();
  81         rcu_read_lock();
  82         if (ifindex == 0) {
  83                 struct rt6_info *rt;
  84
  85                 rt = rt6_lookup(net, addr, NULL, 0, 0);
  86                 if (rt) {
  87                         dev = rt->dst.dev;
  88                         ip6_rt_put(rt);
  89                 } else if (ishost) {
  90                         err = -EADDRNOTAVAIL;
  91                         goto error;
  92                 } else {
  93                         /* router, no matching interface: just pick one */
  94                         dev = dev_get_by_flags_rcu(net, IFF_UP,
  95                                                    IFF_UP | IFF_LOOPBACK);
  96                 }
  97         } else
  98                 dev = dev_get_by_index_rcu(net, ifindex);
  99
 100         if (dev == NULL) {
 101                 err = -ENODEV;
 102                 goto error;
 103         }
 104
 105         idev = __in6_dev_get(dev);
 106         if (!idev) {
 107                 if (ifindex)
 108                         err = -ENODEV;
 109                 else
 110                         err = -EADDRNOTAVAIL;
 111                 goto error;
 112         }
 113         /* reset ishost, now that we have a specific device */
 114         ishost = !idev->cnf.forwarding;
 115
 116         pac->acl_ifindex = dev->ifindex;
 117
 118         /* XXX
 119          * For hosts, allow link-local or matching prefix anycasts.
 120          * This obviates the need for propagating anycast routes while
 121          * still allowing some non-router anycast participation.
 122          */
 123         if (!ipv6_chk_prefix(addr, dev)) {
 124                 if (ishost)
 125                         err = -EADDRNOTAVAIL;
 126                 if (err)
 127                         goto error;
 128         }
 129
 130         err = ipv6_dev_ac_inc(dev, addr);
 131         if (!err) {
 132                 spin_lock_bh(&ipv6_sk_ac_lock);
 133                 pac->acl_next = np->ipv6_ac_list;
 134                 np->ipv6_ac_list = pac;
 135                 spin_unlock_bh(&ipv6_sk_ac_lock);
 136                 pac = NULL;
 137         }
 138
 139 error:
 140         rcu_read_unlock();
 141         rtnl_unlock();
 142         if (pac)
 143                 sock_kfree_s(sk, pac, sizeof(*pac));
 144         return err;
 145 }
 146
 147 /*
 148  *      socket leave an anycast group
 149  */
 150 int ipv6_sock_ac_drop(struct sock *sk, int ifindex, const struct in6_addr *addr)
 151 {
 152         struct ipv6_pinfo *np = inet6_sk(sk);
 153         struct net_device *dev;
 154         struct ipv6_ac_socklist *pac, *prev_pac;
 155         struct net *net = sock_net(sk);
 156
 157         spin_lock_bh(&ipv6_sk_ac_lock);
 158         prev_pac = NULL;
 159         for (pac = np->ipv6_ac_list; pac; pac = pac->acl_next) {
 160                 if ((ifindex == 0 || pac->acl_ifindex == ifindex) &&
 161                      ipv6_addr_equal(&pac->acl_addr, addr))
 162                         break;
 163                 prev_pac = pac;
 164         }
 165         if (!pac) {
 166                 spin_unlock_bh(&ipv6_sk_ac_lock);
 167                 return -ENOENT;
 168         }
 169         if (prev_pac)
 170                 prev_pac->acl_next = pac->acl_next;
 171         else
 172                 np->ipv6_ac_list = pac->acl_next;
 173
 174         spin_unlock_bh(&ipv6_sk_ac_lock);
 175
 176         rtnl_lock();
 177         rcu_read_lock();
 178         dev = dev_get_by_index_rcu(net, pac->acl_ifindex);
 179         if (dev)
 180                 ipv6_dev_ac_dec(dev, &pac->acl_addr);
 181         rcu_read_unlock();
 182         rtnl_unlock();
 183
 184         sock_kfree_s(sk, pac, sizeof(*pac));
 185         return 0;
 186 }
 187
 188 void ipv6_sock_ac_close(struct sock *sk)
 189 {
 190         struct ipv6_pinfo *np = inet6_sk(sk);
 191         struct net_device *dev = NULL;
 192         struct ipv6_ac_socklist *pac;
 193         struct net *net = sock_net(sk);
 194         int     prev_index;
 195
 196         if (!np->ipv6_ac_list)
 197                 return;
 198
 199         spin_lock_bh(&ipv6_sk_ac_lock);
 200         pac = np->ipv6_ac_list;
 201         np->ipv6_ac_list = NULL;
 202         spin_unlock_bh(&ipv6_sk_ac_lock);
 203
 204         prev_index = 0;
 205         rtnl_lock();
 206         rcu_read_lock();
 207         while (pac) {
 208                 struct ipv6_ac_socklist *next = pac->acl_next;
 209
 210                 if (pac->acl_ifindex != prev_index) {
 211                         dev = dev_get_by_index_rcu(net, pac->acl_ifindex);
 212                         prev_index = pac->acl_ifindex;
 213                 }
 214                 if (dev)
 215                         ipv6_dev_ac_dec(dev, &pac->acl_addr);
 216                 sock_kfree_s(sk, pac, sizeof(*pac));
 217                 pac = next;
 218         }
 219         rcu_read_unlock();
 220         rtnl_unlock();
 221 }
 222
 223 static void aca_put(struct ifacaddr6 *ac)
 224 {
 225         if (atomic_dec_and_test(&ac->aca_refcnt)) {
 226                 in6_dev_put(ac->aca_idev);
 227                 dst_release(&ac->aca_rt->dst);
 228                 kfree(ac);
 229         }
 230 }
 231
 232 /*
 233  *      device anycast group inc (add if not found)
 234  */
 235 int ipv6_dev_ac_inc(struct net_device *dev, const struct in6_addr *addr)
 236 {
 237         struct ifacaddr6 *aca;
 238         struct inet6_dev *idev;
 239         struct rt6_info *rt;
 240         int err;
 241
 242         ASSERT_RTNL();
 243
 244         idev = in6_dev_get(dev);
 245
 246         if (idev == NULL)
 247                 return -EINVAL;
 248
 249         write_lock_bh(&idev->lock);
 250         if (idev->dead) {
 251                 err = -ENODEV;
 252                 goto out;
 253         }
 254
 255         for (aca = idev->ac_list; aca; aca = aca->aca_next) {
 256                 if (ipv6_addr_equal(&aca->aca_addr, addr)) {
 257                         aca->aca_users++;
 258                         err = 0;
 259                         goto out;
 260                 }
 261         }
 262
 263         /*
 264          *      not found: create a new one.
 265          */
 266
 267         aca = kzalloc(sizeof(struct ifacaddr6), GFP_ATOMIC);
 268
 269         if (aca == NULL) {
 270                 err = -ENOMEM;
 271                 goto out;
 272         }
 273
 274         rt = addrconf_dst_alloc(idev, addr, true);
 275         if (IS_ERR(rt)) {
 276                 kfree(aca);
 277                 err = PTR_ERR(rt);
 278                 goto out;
 279         }
 280
 281         aca->aca_addr = *addr;
 282         aca->aca_idev = idev;
 283         aca->aca_rt = rt;
 284         aca->aca_users = 1;
 285         /* aca_tstamp should be updated upon changes */
 286         aca->aca_cstamp = aca->aca_tstamp = jiffies;
 287         atomic_set(&aca->aca_refcnt, 2);
 288         spin_lock_init(&aca->aca_lock);
 289
 290         aca->aca_next = idev->ac_list;
 291         idev->ac_list = aca;
 292         write_unlock_bh(&idev->lock);
 293
 294         ip6_ins_rt(rt);
 295
 296         addrconf_join_solict(dev, &aca->aca_addr);
 297
 298         aca_put(aca);
 299         return 0;
 300 out:
 301         write_unlock_bh(&idev->lock);
 302         in6_dev_put(idev);
 303         return err;
 304 }
 305
 306 /*
 307  *      device anycast group decrement
 308  */
 309 int __ipv6_dev_ac_dec(struct inet6_dev *idev, const struct in6_addr *addr)
 310 {
 311         struct ifacaddr6 *aca, *prev_aca;
 312
 313         ASSERT_RTNL();
 314
 315         write_lock_bh(&idev->lock);
 316         prev_aca = NULL;
 317         for (aca = idev->ac_list; aca; aca = aca->aca_next) {
 318                 if (ipv6_addr_equal(&aca->aca_addr, addr))
 319                         break;
 320                 prev_aca = aca;
 321         }
 322         if (!aca) {
 323                 write_unlock_bh(&idev->lock);
 324                 return -ENOENT;
 325         }
 326         if (--aca->aca_users > 0) {
 327                 write_unlock_bh(&idev->lock);
 328                 return 0;
 329         }
 330         if (prev_aca)
 331                 prev_aca->aca_next = aca->aca_next;
 332         else
 333                 idev->ac_list = aca->aca_next;
 334         write_unlock_bh(&idev->lock);
 335         addrconf_leave_solict(idev, &aca->aca_addr);
 336
 337         dst_hold(&aca->aca_rt->dst);
 338         ip6_del_rt(aca->aca_rt);
 339
 340         aca_put(aca);
 341         return 0;
 342 }
 343
 344 /* called with rcu_read_lock() */
 345 static int ipv6_dev_ac_dec(struct net_device *dev, const struct in6_addr *addr)
 346 {
 347         struct inet6_dev *idev = __in6_dev_get(dev);
 348
 349         if (idev == NULL)
 350                 return -ENODEV;
 351         return __ipv6_dev_ac_dec(idev, addr);
 352 }
 353
 354 void ipv6_ac_destroy_dev(struct inet6_dev *idev)
 355 {
 356         struct ifacaddr6 *aca;
 357
 358         write_lock_bh(&idev->lock);
 359         while ((aca = idev->ac_list) != NULL) {
 360                 idev->ac_list = aca->aca_next;
 361                 write_unlock_bh(&idev->lock);
 362
 363                 addrconf_leave_solict(idev, &aca->aca_addr);
 364
 365                 dst_hold(&aca->aca_rt->dst);
 366                 ip6_del_rt(aca->aca_rt);
 367
 368                 aca_put(aca);
 369
 370                 write_lock_bh(&idev->lock);
 371         }
 372         write_unlock_bh(&idev->lock);
 373 }
 374
 375 /*
 376  *      check if the interface has this anycast address
 377  *      called with rcu_read_lock()
 378  */
 379 static bool ipv6_chk_acast_dev(struct net_device *dev, const struct in6_addr *addr)
 380 {
 381         struct inet6_dev *idev;
 382         struct ifacaddr6 *aca;
 383
 384         idev = __in6_dev_get(dev);
 385         if (idev) {
 386                 read_lock_bh(&idev->lock);
 387                 for (aca = idev->ac_list; aca; aca = aca->aca_next)
 388                         if (ipv6_addr_equal(&aca->aca_addr, addr))
 389                                 break;
 390                 read_unlock_bh(&idev->lock);
 391                 return aca != NULL;
 392         }
 393         return false;
 394 }
 395
 396 /*
 397  *      check if given interface (or any, if dev==0) has this anycast address
 398  */
 399 bool ipv6_chk_acast_addr(struct net *net, struct net_device *dev,
 400                          const struct in6_addr *addr)
 401 {
 402         bool found = false;
 403
 404         rcu_read_lock();
 405         if (dev)
 406                 found = ipv6_chk_acast_dev(dev, addr);
 407         else
 408                 for_each_netdev_rcu(net, dev)
 409                         if (ipv6_chk_acast_dev(dev, addr)) {
 410                                 found = true;
 411                                 break;
 412                         }
 413         rcu_read_unlock();
 414         return found;
 415 }
 416
 417 /*      check if this anycast address is link-local on given interface or
 418  *      is global
 419  */
 420 bool ipv6_chk_acast_addr_src(struct net *net, struct net_device *dev,
 421                              const struct in6_addr *addr)
 422 {
 423         return ipv6_chk_acast_addr(net,
 424                                    (ipv6_addr_type(addr) & IPV6_ADDR_LINKLOCAL ?
 425                                     dev : NULL),
 426                                    addr);
 427 }
 428
 429 #ifdef CONFIG_PROC_FS
 430 struct ac6_iter_state {
 431         struct seq_net_private p;
 432         struct net_device *dev;
 433         struct inet6_dev *idev;
 434 };
 435
 436 #define ac6_seq_private(seq)    ((struct ac6_iter_state *)(seq)->private)
 437
 438 static inline struct ifacaddr6 *ac6_get_first(struct seq_file *seq)
 439 {
 440         struct ifacaddr6 *im = NULL;
 441         struct ac6_iter_state *state = ac6_seq_private(seq);
 442         struct net *net = seq_file_net(seq);
 443
 444         state->idev = NULL;
 445         for_each_netdev_rcu(net, state->dev) {
 446                 struct inet6_dev *idev;
 447                 idev = __in6_dev_get(state->dev);
 448                 if (!idev)
 449                         continue;
 450                 read_lock_bh(&idev->lock);
 451                 im = idev->ac_list;
 452                 if (im) {
 453                         state->idev = idev;
 454                         break;
 455                 }
 456                 read_unlock_bh(&idev->lock);
 457         }
 458         return im;
 459 }
 460
 461 static struct ifacaddr6 *ac6_get_next(struct seq_file *seq, struct ifacaddr6 *im)
 462 {
 463         struct ac6_iter_state *state = ac6_seq_private(seq);
 464
 465         im = im->aca_next;
 466         while (!im) {
 467                 if (likely(state->idev != NULL))
 468                         read_unlock_bh(&state->idev->lock);
 469
 470                 state->dev = next_net_device_rcu(state->dev);
 471                 if (!state->dev) {
 472                         state->idev = NULL;
 473                         break;
 474                 }
 475                 state->idev = __in6_dev_get(state->dev);
 476                 if (!state->idev)
 477                         continue;
 478                 read_lock_bh(&state->idev->lock);
 479                 im = state->idev->ac_list;
 480         }
 481         return im;
 482 }
 483
 484 static struct ifacaddr6 *ac6_get_idx(struct seq_file *seq, loff_t pos)
 485 {
 486         struct ifacaddr6 *im = ac6_get_first(seq);
 487         if (im)
 488                 while (pos && (im = ac6_get_next(seq, im)) != NULL)
 489                         --pos;
 490         return pos ? NULL : im;
 491 }
 492
 493 static void *ac6_seq_start(struct seq_file *seq, loff_t *pos)
 494         __acquires(RCU)
 495 {
 496         rcu_read_lock();
 497         return ac6_get_idx(seq, *pos);
 498 }
 499
 500 static void *ac6_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 501 {
 502         struct ifacaddr6 *im = ac6_get_next(seq, v);
 503
 504         ++*pos;
 505         return im;
 506 }
 507
 508 static void ac6_seq_stop(struct seq_file *seq, void *v)
 509         __releases(RCU)
 510 {
 511         struct ac6_iter_state *state = ac6_seq_private(seq);
 512
 513         if (likely(state->idev != NULL)) {
 514                 read_unlock_bh(&state->idev->lock);
 515                 state->idev = NULL;
 516         }
 517         rcu_read_unlock();
 518 }
 519
 520 static int ac6_seq_show(struct seq_file *seq, void *v)
 521 {
 522         struct ifacaddr6 *im = (struct ifacaddr6 *)v;
 523         struct ac6_iter_state *state = ac6_seq_private(seq);
 524
 525         seq_printf(seq, "%-4d %-15s %pi6 %5d\n",
 526                    state->dev->ifindex, state->dev->name,
 527                    &im->aca_addr, im->aca_users);
 528         return 0;
 529 }
 530
 531 static const struct seq_operations ac6_seq_ops = {
 532         .start  =       ac6_seq_start,
 533         .next   =       ac6_seq_next,
 534         .stop   =       ac6_seq_stop,
 535         .show   =       ac6_seq_show,
 536 };
 537
 538 static int ac6_seq_open(struct inode *inode, struct file *file)
 539 {
 540         return seq_open_net(inode, file, &ac6_seq_ops,
 541                             sizeof(struct ac6_iter_state));
 542 }
 543
 544 static const struct file_operations ac6_seq_fops = {
 545         .owner          =       THIS_MODULE,
 546         .open           =       ac6_seq_open,
 547         .read           =       seq_read,
 548         .llseek         =       seq_lseek,
 549         .release        =       seq_release_net,
 550 };
 551
 552 int __net_init ac6_proc_init(struct net *net)
 553 {
 554         if (!proc_create("anycast6", S_IRUGO, net->proc_net, &ac6_seq_fops))
 555                 return -ENOMEM;
 556
 557         return 0;
 558 }
 559
 560 void ac6_proc_exit(struct net *net)
 561 {
 562         remove_proc_entry("anycast6", net->proc_net);
 563 }
 564 #endif
 565