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, struct in6_addr *addr);
  48
  49 /* Big ac list lock for all the sockets */
  50 static DEFINE_RWLOCK(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, 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 (!capable(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         ipv6_addr_copy(&pac->acl_addr, addr);
  79
  80         if (ifindex == 0) {
  81                 struct rt6_info *rt;
  82
  83                 rt = rt6_lookup(net, addr, NULL, 0, 0);
  84                 if (rt) {
  85                         dev = rt->rt6i_dev;
  86                         dev_hold(dev);
  87                         dst_release(&rt->u.dst);
  88                 } else if (ishost) {
  89                         err = -EADDRNOTAVAIL;
  90                         goto out_free_pac;
  91                 } else {
  92                         /* router, no matching interface: just pick one */
  93
  94                         dev = dev_get_by_flags(net, IFF_UP, IFF_UP|IFF_LOOPBACK);
  95                 }
  96         } else
  97                 dev = dev_get_by_index(net, ifindex);
  98
  99         if (dev == NULL) {
 100                 err = -ENODEV;
 101                 goto out_free_pac;
 102         }
 103
 104         idev = in6_dev_get(dev);
 105         if (!idev) {
 106                 if (ifindex)
 107                         err = -ENODEV;
 108                 else
 109                         err = -EADDRNOTAVAIL;
 110                 goto out_dev_put;
 111         }
 112         /* reset ishost, now that we have a specific device */
 113         ishost = !idev->cnf.forwarding;
 114         in6_dev_put(idev);
 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 out_dev_put;
 128         }
 129
 130         err = ipv6_dev_ac_inc(dev, addr);
 131         if (err)
 132                 goto out_dev_put;
 133
 134         write_lock_bh(&ipv6_sk_ac_lock);
 135         pac->acl_next = np->ipv6_ac_list;
 136         np->ipv6_ac_list = pac;
 137         write_unlock_bh(&ipv6_sk_ac_lock);
 138
 139         dev_put(dev);
 140
 141         return 0;
 142
 143 out_dev_put:
 144         dev_put(dev);
 145 out_free_pac:
 146         sock_kfree_s(sk, pac, sizeof(*pac));
 147         return err;
 148 }
 149
 150 /*
 151  *      socket leave an anycast group
 152  */
 153 int ipv6_sock_ac_drop(struct sock *sk, int ifindex, struct in6_addr *addr)
 154 {
 155         struct ipv6_pinfo *np = inet6_sk(sk);
 156         struct net_device *dev;
 157         struct ipv6_ac_socklist *pac, *prev_pac;
 158         struct net *net = sock_net(sk);
 159
 160         write_lock_bh(&ipv6_sk_ac_lock);
 161         prev_pac = NULL;
 162         for (pac = np->ipv6_ac_list; pac; pac = pac->acl_next) {
 163                 if ((ifindex == 0 || pac->acl_ifindex == ifindex) &&
 164                      ipv6_addr_equal(&pac->acl_addr, addr))
 165                         break;
 166                 prev_pac = pac;
 167         }
 168         if (!pac) {
 169                 write_unlock_bh(&ipv6_sk_ac_lock);
 170                 return -ENOENT;
 171         }
 172         if (prev_pac)
 173                 prev_pac->acl_next = pac->acl_next;
 174         else
 175                 np->ipv6_ac_list = pac->acl_next;
 176
 177         write_unlock_bh(&ipv6_sk_ac_lock);
 178
 179         dev = dev_get_by_index(net, pac->acl_ifindex);
 180         if (dev) {
 181                 ipv6_dev_ac_dec(dev, &pac->acl_addr);
 182                 dev_put(dev);
 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         write_lock_bh(&ipv6_sk_ac_lock);
 197         pac = np->ipv6_ac_list;
 198         np->ipv6_ac_list = NULL;
 199         write_unlock_bh(&ipv6_sk_ac_lock);
 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                         if (dev)
 207                                 dev_put(dev);
 208                         dev = dev_get_by_index(net, pac->acl_ifindex);
 209                         prev_index = pac->acl_ifindex;
 210                 }
 211                 if (dev)
 212                         ipv6_dev_ac_dec(dev, &pac->acl_addr);
 213                 sock_kfree_s(sk, pac, sizeof(*pac));
 214                 pac = next;
 215         }
 216         if (dev)
 217                 dev_put(dev);
 218 }
 219
 220 #if 0
 221 /* The function is not used, which is funny. Apparently, author
 222  * supposed to use it to filter out datagrams inside udp/raw but forgot.
 223  *
 224  * It is OK, anycasts are not special comparing to delivery to unicasts.
 225  */
 226
 227 int inet6_ac_check(struct sock *sk, struct in6_addr *addr, int ifindex)
 228 {
 229         struct ipv6_ac_socklist *pac;
 230         struct ipv6_pinfo *np = inet6_sk(sk);
 231         int     found;
 232
 233         found = 0;
 234         read_lock(&ipv6_sk_ac_lock);
 235         for (pac=np->ipv6_ac_list; pac; pac=pac->acl_next) {
 236                 if (ifindex && pac->acl_ifindex != ifindex)
 237                         continue;
 238                 found = ipv6_addr_equal(&pac->acl_addr, addr);
 239                 if (found)
 240                         break;
 241         }
 242         read_unlock(&ipv6_sk_ac_lock);
 243
 244         return found;
 245 }
 246
 247 #endif
 248
 249 static void aca_put(struct ifacaddr6 *ac)
 250 {
 251         if (atomic_dec_and_test(&ac->aca_refcnt)) {
 252                 in6_dev_put(ac->aca_idev);
 253                 dst_release(&ac->aca_rt->u.dst);
 254                 kfree(ac);
 255         }
 256 }
 257
 258 /*
 259  *      device anycast group inc (add if not found)
 260  */
 261 int ipv6_dev_ac_inc(struct net_device *dev, struct in6_addr *addr)
 262 {
 263         struct ifacaddr6 *aca;
 264         struct inet6_dev *idev;
 265         struct rt6_info *rt;
 266         int err;
 267
 268         idev = in6_dev_get(dev);
 269
 270         if (idev == NULL)
 271                 return -EINVAL;
 272
 273         write_lock_bh(&idev->lock);
 274         if (idev->dead) {
 275                 err = -ENODEV;
 276                 goto out;
 277         }
 278
 279         for (aca = idev->ac_list; aca; aca = aca->aca_next) {
 280                 if (ipv6_addr_equal(&aca->aca_addr, addr)) {
 281                         aca->aca_users++;
 282                         err = 0;
 283                         goto out;
 284                 }
 285         }
 286
 287         /*
 288          *      not found: create a new one.
 289          */
 290
 291         aca = kzalloc(sizeof(struct ifacaddr6), GFP_ATOMIC);
 292
 293         if (aca == NULL) {
 294                 err = -ENOMEM;
 295                 goto out;
 296         }
 297
 298         rt = addrconf_dst_alloc(idev, addr, 1);
 299         if (IS_ERR(rt)) {
 300                 kfree(aca);
 301                 err = PTR_ERR(rt);
 302                 goto out;
 303         }
 304
 305         ipv6_addr_copy(&aca->aca_addr, addr);
 306         aca->aca_idev = idev;
 307         aca->aca_rt = rt;
 308         aca->aca_users = 1;
 309         /* aca_tstamp should be updated upon changes */
 310         aca->aca_cstamp = aca->aca_tstamp = jiffies;
 311         atomic_set(&aca->aca_refcnt, 2);
 312         spin_lock_init(&aca->aca_lock);
 313
 314         aca->aca_next = idev->ac_list;
 315         idev->ac_list = aca;
 316         write_unlock_bh(&idev->lock);
 317
 318         ip6_ins_rt(rt);
 319
 320         addrconf_join_solict(dev, &aca->aca_addr);
 321
 322         aca_put(aca);
 323         return 0;
 324 out:
 325         write_unlock_bh(&idev->lock);
 326         in6_dev_put(idev);
 327         return err;
 328 }
 329
 330 /*
 331  *      device anycast group decrement
 332  */
 333 int __ipv6_dev_ac_dec(struct inet6_dev *idev, struct in6_addr *addr)
 334 {
 335         struct ifacaddr6 *aca, *prev_aca;
 336
 337         write_lock_bh(&idev->lock);
 338         prev_aca = NULL;
 339         for (aca = idev->ac_list; aca; aca = aca->aca_next) {
 340                 if (ipv6_addr_equal(&aca->aca_addr, addr))
 341                         break;
 342                 prev_aca = aca;
 343         }
 344         if (!aca) {
 345                 write_unlock_bh(&idev->lock);
 346                 return -ENOENT;
 347         }
 348         if (--aca->aca_users > 0) {
 349                 write_unlock_bh(&idev->lock);
 350                 return 0;
 351         }
 352         if (prev_aca)
 353                 prev_aca->aca_next = aca->aca_next;
 354         else
 355                 idev->ac_list = aca->aca_next;
 356         write_unlock_bh(&idev->lock);
 357         addrconf_leave_solict(idev, &aca->aca_addr);
 358
 359         dst_hold(&aca->aca_rt->u.dst);
 360         ip6_del_rt(aca->aca_rt);
 361
 362         aca_put(aca);
 363         return 0;
 364 }
 365
 366 static int ipv6_dev_ac_dec(struct net_device *dev, struct in6_addr *addr)
 367 {
 368         int ret;
 369         struct inet6_dev *idev = in6_dev_get(dev);
 370         if (idev == NULL)
 371                 return -ENODEV;
 372         ret = __ipv6_dev_ac_dec(idev, addr);
 373         in6_dev_put(idev);
 374         return ret;
 375 }
 376
 377 /*
 378  *      check if the interface has this anycast address
 379  */
 380 static int ipv6_chk_acast_dev(struct net_device *dev, struct in6_addr *addr)
 381 {
 382         struct inet6_dev *idev;
 383         struct ifacaddr6 *aca;
 384
 385         idev = in6_dev_get(dev);
 386         if (idev) {
 387                 read_lock_bh(&idev->lock);
 388                 for (aca = idev->ac_list; aca; aca = aca->aca_next)
 389                         if (ipv6_addr_equal(&aca->aca_addr, addr))
 390                                 break;
 391                 read_unlock_bh(&idev->lock);
 392                 in6_dev_put(idev);
 393                 return aca != NULL;
 394         }
 395         return 0;
 396 }
 397
 398 /*
 399  *      check if given interface (or any, if dev==0) has this anycast address
 400  */
 401 int ipv6_chk_acast_addr(struct net *net, struct net_device *dev,
 402                         struct in6_addr *addr)
 403 {
 404         int found = 0;
 405
 406         if (dev)
 407                 return ipv6_chk_acast_dev(dev, addr);
 408         rcu_read_lock();
 409         for_each_netdev_rcu(net, dev)
 410                 if (ipv6_chk_acast_dev(dev, addr)) {
 411                         found = 1;
 412                         break;
 413                 }
 414         rcu_read_unlock();
 415         return found;
 416 }
 417
 418
 419 #ifdef CONFIG_PROC_FS
 420 struct ac6_iter_state {
 421         struct seq_net_private p;
 422         struct net_device *dev;
 423         struct inet6_dev *idev;
 424 };
 425
 426 #define ac6_seq_private(seq)    ((struct ac6_iter_state *)(seq)->private)
 427
 428 static inline struct ifacaddr6 *ac6_get_first(struct seq_file *seq)
 429 {
 430         struct ifacaddr6 *im = NULL;
 431         struct ac6_iter_state *state = ac6_seq_private(seq);
 432         struct net *net = seq_file_net(seq);
 433
 434         state->idev = NULL;
 435         for_each_netdev_rcu(net, state->dev) {
 436                 struct inet6_dev *idev;
 437                 idev = __in6_dev_get(state->dev);
 438                 if (!idev)
 439                         continue;
 440                 read_lock_bh(&idev->lock);
 441                 im = idev->ac_list;
 442                 if (im) {
 443                         state->idev = idev;
 444                         break;
 445                 }
 446                 read_unlock_bh(&idev->lock);
 447         }
 448         return im;
 449 }
 450
 451 static struct ifacaddr6 *ac6_get_next(struct seq_file *seq, struct ifacaddr6 *im)
 452 {
 453         struct ac6_iter_state *state = ac6_seq_private(seq);
 454
 455         im = im->aca_next;
 456         while (!im) {
 457                 if (likely(state->idev != NULL))
 458                         read_unlock_bh(&state->idev->lock);
 459
 460                 state->dev = next_net_device_rcu(state->dev);
 461                 if (!state->dev) {
 462                         state->idev = NULL;
 463                         break;
 464                 }
 465                 state->idev = __in6_dev_get(state->dev);
 466                 if (!state->idev)
 467                         continue;
 468                 read_lock_bh(&state->idev->lock);
 469                 im = state->idev->ac_list;
 470         }
 471         return im;
 472 }
 473
 474 static struct ifacaddr6 *ac6_get_idx(struct seq_file *seq, loff_t pos)
 475 {
 476         struct ifacaddr6 *im = ac6_get_first(seq);
 477         if (im)
 478                 while (pos && (im = ac6_get_next(seq, im)) != NULL)
 479                         --pos;
 480         return pos ? NULL : im;
 481 }
 482
 483 static void *ac6_seq_start(struct seq_file *seq, loff_t *pos)
 484         __acquires(RCU)
 485 {
 486         rcu_read_lock();
 487         return ac6_get_idx(seq, *pos);
 488 }
 489
 490 static void *ac6_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 491 {
 492         struct ifacaddr6 *im = ac6_get_next(seq, v);
 493
 494         ++*pos;
 495         return im;
 496 }
 497
 498 static void ac6_seq_stop(struct seq_file *seq, void *v)
 499         __releases(RCU)
 500 {
 501         struct ac6_iter_state *state = ac6_seq_private(seq);
 502
 503         if (likely(state->idev != NULL)) {
 504                 read_unlock_bh(&state->idev->lock);
 505                 state->idev = NULL;
 506         }
 507         rcu_read_unlock();
 508 }
 509
 510 static int ac6_seq_show(struct seq_file *seq, void *v)
 511 {
 512         struct ifacaddr6 *im = (struct ifacaddr6 *)v;
 513         struct ac6_iter_state *state = ac6_seq_private(seq);
 514
 515         seq_printf(seq, "%-4d %-15s %pi6 %5d\n",
 516                    state->dev->ifindex, state->dev->name,
 517                    &im->aca_addr, im->aca_users);
 518         return 0;
 519 }
 520
 521 static const struct seq_operations ac6_seq_ops = {
 522         .start  =       ac6_seq_start,
 523         .next   =       ac6_seq_next,
 524         .stop   =       ac6_seq_stop,
 525         .show   =       ac6_seq_show,
 526 };
 527
 528 static int ac6_seq_open(struct inode *inode, struct file *file)
 529 {
 530         return seq_open_net(inode, file, &ac6_seq_ops,
 531                             sizeof(struct ac6_iter_state));
 532 }
 533
 534 static const struct file_operations ac6_seq_fops = {
 535         .owner          =       THIS_MODULE,
 536         .open           =       ac6_seq_open,
 537         .read           =       seq_read,
 538         .llseek         =       seq_lseek,
 539         .release        =       seq_release_net,
 540 };
 541
 542 int __net_init ac6_proc_init(struct net *net)
 543 {
 544         if (!proc_net_fops_create(net, "anycast6", S_IRUGO, &ac6_seq_fops))
 545                 return -ENOMEM;
 546
 547         return 0;
 548 }
 549
 550 void ac6_proc_exit(struct net *net)
 551 {
 552         proc_net_remove(net, "anycast6");
 553 }
 554 #endif
 555