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 /*
  50  *      socket join an anycast group
  51  */
  52
  53 int ipv6_sock_ac_join(struct sock *sk, int ifindex, const struct in6_addr *addr)
  54 {
  55         struct ipv6_pinfo *np = inet6_sk(sk);
  56         struct net_device *dev = NULL;
  57         struct inet6_dev *idev;
  58         struct ipv6_ac_socklist *pac;
  59         struct net *net = sock_net(sk);
  60         int     ishost = !net->ipv6.devconf_all->forwarding;
  61         int     err = 0;
  62
  63         if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
  64                 return -EPERM;
  65         if (ipv6_addr_is_multicast(addr))
  66                 return -EINVAL;
  67         if (ipv6_chk_addr(net, addr, NULL, 0))
  68                 return -EINVAL;
  69
  70         pac = sock_kmalloc(sk, sizeof(struct ipv6_ac_socklist), GFP_KERNEL);
  71         if (pac == NULL)
  72                 return -ENOMEM;
  73         pac->acl_next = NULL;
  74         pac->acl_addr = *addr;
  75
  76         rtnl_lock();
  77         if (ifindex == 0) {
  78                 struct rt6_info *rt;
  79
  80                 rt = rt6_lookup(net, addr, NULL, 0, 0);
  81                 if (rt) {
  82                         dev = rt->dst.dev;
  83                         ip6_rt_put(rt);
  84                 } else if (ishost) {
  85                         err = -EADDRNOTAVAIL;
  86                         goto error;
  87                 } else {
  88                         /* router, no matching interface: just pick one */
  89                         dev = __dev_get_by_flags(net, IFF_UP,
  90                                                  IFF_UP | IFF_LOOPBACK);
  91                 }
  92         } else
  93                 dev = __dev_get_by_index(net, ifindex);
  94
  95         if (dev == NULL) {
  96                 err = -ENODEV;
  97                 goto error;
  98         }
  99
 100         idev = __in6_dev_get(dev);
 101         if (!idev) {
 102                 if (ifindex)
 103                         err = -ENODEV;
 104                 else
 105                         err = -EADDRNOTAVAIL;
 106                 goto error;
 107         }
 108         /* reset ishost, now that we have a specific device */
 109         ishost = !idev->cnf.forwarding;
 110
 111         pac->acl_ifindex = dev->ifindex;
 112
 113         /* XXX
 114          * For hosts, allow link-local or matching prefix anycasts.
 115          * This obviates the need for propagating anycast routes while
 116          * still allowing some non-router anycast participation.
 117          */
 118         if (!ipv6_chk_prefix(addr, dev)) {
 119                 if (ishost)
 120                         err = -EADDRNOTAVAIL;
 121                 if (err)
 122                         goto error;
 123         }
 124
 125         err = __ipv6_dev_ac_inc(idev, addr);
 126         if (!err) {
 127                 pac->acl_next = np->ipv6_ac_list;
 128                 np->ipv6_ac_list = pac;
 129                 pac = NULL;
 130         }
 131
 132 error:
 133         rtnl_unlock();
 134         if (pac)
 135                 sock_kfree_s(sk, pac, sizeof(*pac));
 136         return err;
 137 }
 138
 139 /*
 140  *      socket leave an anycast group
 141  */
 142 int ipv6_sock_ac_drop(struct sock *sk, int ifindex, const struct in6_addr *addr)
 143 {
 144         struct ipv6_pinfo *np = inet6_sk(sk);
 145         struct net_device *dev;
 146         struct ipv6_ac_socklist *pac, *prev_pac;
 147         struct net *net = sock_net(sk);
 148
 149         rtnl_lock();
 150         prev_pac = NULL;
 151         for (pac = np->ipv6_ac_list; pac; pac = pac->acl_next) {
 152                 if ((ifindex == 0 || pac->acl_ifindex == ifindex) &&
 153                      ipv6_addr_equal(&pac->acl_addr, addr))
 154                         break;
 155                 prev_pac = pac;
 156         }
 157         if (!pac) {
 158                 rtnl_unlock();
 159                 return -ENOENT;
 160         }
 161         if (prev_pac)
 162                 prev_pac->acl_next = pac->acl_next;
 163         else
 164                 np->ipv6_ac_list = pac->acl_next;
 165
 166         dev = __dev_get_by_index(net, pac->acl_ifindex);
 167         if (dev)
 168                 ipv6_dev_ac_dec(dev, &pac->acl_addr);
 169         rtnl_unlock();
 170
 171         sock_kfree_s(sk, pac, sizeof(*pac));
 172         return 0;
 173 }
 174
 175 void ipv6_sock_ac_close(struct sock *sk)
 176 {
 177         struct ipv6_pinfo *np = inet6_sk(sk);
 178         struct net_device *dev = NULL;
 179         struct ipv6_ac_socklist *pac;
 180         struct net *net = sock_net(sk);
 181         int     prev_index;
 182
 183         if (!np->ipv6_ac_list)
 184                 return;
 185
 186         rtnl_lock();
 187         pac = np->ipv6_ac_list;
 188         np->ipv6_ac_list = NULL;
 189
 190         prev_index = 0;
 191         while (pac) {
 192                 struct ipv6_ac_socklist *next = pac->acl_next;
 193
 194                 if (pac->acl_ifindex != prev_index) {
 195                         dev = __dev_get_by_index(net, pac->acl_ifindex);
 196                         prev_index = pac->acl_ifindex;
 197                 }
 198                 if (dev)
 199                         ipv6_dev_ac_dec(dev, &pac->acl_addr);
 200                 sock_kfree_s(sk, pac, sizeof(*pac));
 201                 pac = next;
 202         }
 203         rtnl_unlock();
 204 }
 205
 206 static void aca_get(struct ifacaddr6 *aca)
 207 {
 208         atomic_inc(&aca->aca_refcnt);
 209 }
 210
 211 static void aca_put(struct ifacaddr6 *ac)
 212 {
 213         if (atomic_dec_and_test(&ac->aca_refcnt)) {
 214                 in6_dev_put(ac->aca_idev);
 215                 dst_release(&ac->aca_rt->dst);
 216                 kfree(ac);
 217         }
 218 }
 219
 220 static struct ifacaddr6 *aca_alloc(struct rt6_info *rt,
 221                                    const struct in6_addr *addr)
 222 {
 223         struct inet6_dev *idev = rt->rt6i_idev;
 224         struct ifacaddr6 *aca;
 225
 226         aca = kzalloc(sizeof(*aca), GFP_ATOMIC);
 227         if (aca == NULL)
 228                 return NULL;
 229
 230         aca->aca_addr = *addr;
 231         in6_dev_hold(idev);
 232         aca->aca_idev = idev;
 233         aca->aca_rt = rt;
 234         aca->aca_users = 1;
 235         /* aca_tstamp should be updated upon changes */
 236         aca->aca_cstamp = aca->aca_tstamp = jiffies;
 237         atomic_set(&aca->aca_refcnt, 1);
 238
 239         return aca;
 240 }
 241
 242 /*
 243  *      device anycast group inc (add if not found)
 244  */
 245 int __ipv6_dev_ac_inc(struct inet6_dev *idev, const struct in6_addr *addr)
 246 {
 247         struct ifacaddr6 *aca;
 248         struct rt6_info *rt;
 249         int err;
 250
 251         ASSERT_RTNL();
 252
 253         write_lock_bh(&idev->lock);
 254         if (idev->dead) {
 255                 err = -ENODEV;
 256                 goto out;
 257         }
 258
 259         for (aca = idev->ac_list; aca; aca = aca->aca_next) {
 260                 if (ipv6_addr_equal(&aca->aca_addr, addr)) {
 261                         aca->aca_users++;
 262                         err = 0;
 263                         goto out;
 264                 }
 265         }
 266
 267         rt = addrconf_dst_alloc(idev, addr, true);
 268         if (IS_ERR(rt)) {
 269                 err = PTR_ERR(rt);
 270                 goto out;
 271         }
 272         aca = aca_alloc(rt, addr);
 273         if (aca == NULL) {
 274                 ip6_rt_put(rt);
 275                 err = -ENOMEM;
 276                 goto out;
 277         }
 278
 279         aca->aca_next = idev->ac_list;
 280         idev->ac_list = aca;
 281
 282         /* Hold this for addrconf_join_solict() below before we unlock,
 283          * it is already exposed via idev->ac_list.
 284          */
 285         aca_get(aca);
 286         write_unlock_bh(&idev->lock);
 287
 288         ip6_ins_rt(rt);
 289
 290         addrconf_join_solict(idev->dev, &aca->aca_addr);
 291
 292         aca_put(aca);
 293         return 0;
 294 out:
 295         write_unlock_bh(&idev->lock);
 296         return err;
 297 }
 298
 299 /*
 300  *      device anycast group decrement
 301  */
 302 int __ipv6_dev_ac_dec(struct inet6_dev *idev, const struct in6_addr *addr)
 303 {
 304         struct ifacaddr6 *aca, *prev_aca;
 305
 306         ASSERT_RTNL();
 307
 308         write_lock_bh(&idev->lock);
 309         prev_aca = NULL;
 310         for (aca = idev->ac_list; aca; aca = aca->aca_next) {
 311                 if (ipv6_addr_equal(&aca->aca_addr, addr))
 312                         break;
 313                 prev_aca = aca;
 314         }
 315         if (!aca) {
 316                 write_unlock_bh(&idev->lock);
 317                 return -ENOENT;
 318         }
 319         if (--aca->aca_users > 0) {
 320                 write_unlock_bh(&idev->lock);
 321                 return 0;
 322         }
 323         if (prev_aca)
 324                 prev_aca->aca_next = aca->aca_next;
 325         else
 326                 idev->ac_list = aca->aca_next;
 327         write_unlock_bh(&idev->lock);
 328         addrconf_leave_solict(idev, &aca->aca_addr);
 329
 330         dst_hold(&aca->aca_rt->dst);
 331         ip6_del_rt(aca->aca_rt);
 332
 333         aca_put(aca);
 334         return 0;
 335 }
 336
 337 /* called with rtnl_lock() */
 338 static int ipv6_dev_ac_dec(struct net_device *dev, const struct in6_addr *addr)
 339 {
 340         struct inet6_dev *idev = __in6_dev_get(dev);
 341
 342         if (idev == NULL)
 343                 return -ENODEV;
 344         return __ipv6_dev_ac_dec(idev, addr);
 345 }
 346
 347 void ipv6_ac_destroy_dev(struct inet6_dev *idev)
 348 {
 349         struct ifacaddr6 *aca;
 350
 351         write_lock_bh(&idev->lock);
 352         while ((aca = idev->ac_list) != NULL) {
 353                 idev->ac_list = aca->aca_next;
 354                 write_unlock_bh(&idev->lock);
 355
 356                 addrconf_leave_solict(idev, &aca->aca_addr);
 357
 358                 dst_hold(&aca->aca_rt->dst);
 359                 ip6_del_rt(aca->aca_rt);
 360
 361                 aca_put(aca);
 362
 363                 write_lock_bh(&idev->lock);
 364         }
 365         write_unlock_bh(&idev->lock);
 366 }
 367
 368 /*
 369  *      check if the interface has this anycast address
 370  *      called with rcu_read_lock()
 371  */
 372 static bool ipv6_chk_acast_dev(struct net_device *dev, const struct in6_addr *addr)
 373 {
 374         struct inet6_dev *idev;
 375         struct ifacaddr6 *aca;
 376
 377         idev = __in6_dev_get(dev);
 378         if (idev) {
 379                 read_lock_bh(&idev->lock);
 380                 for (aca = idev->ac_list; aca; aca = aca->aca_next)
 381                         if (ipv6_addr_equal(&aca->aca_addr, addr))
 382                                 break;
 383                 read_unlock_bh(&idev->lock);
 384                 return aca != NULL;
 385         }
 386         return false;
 387 }
 388
 389 /*
 390  *      check if given interface (or any, if dev==0) has this anycast address
 391  */
 392 bool ipv6_chk_acast_addr(struct net *net, struct net_device *dev,
 393                          const struct in6_addr *addr)
 394 {
 395         bool found = false;
 396
 397         rcu_read_lock();
 398         if (dev)
 399                 found = ipv6_chk_acast_dev(dev, addr);
 400         else
 401                 for_each_netdev_rcu(net, dev)
 402                         if (ipv6_chk_acast_dev(dev, addr)) {
 403                                 found = true;
 404                                 break;
 405                         }
 406         rcu_read_unlock();
 407         return found;
 408 }
 409
 410 /*      check if this anycast address is link-local on given interface or
 411  *      is global
 412  */
 413 bool ipv6_chk_acast_addr_src(struct net *net, struct net_device *dev,
 414                              const struct in6_addr *addr)
 415 {
 416         return ipv6_chk_acast_addr(net,
 417                                    (ipv6_addr_type(addr) & IPV6_ADDR_LINKLOCAL ?
 418                                     dev : NULL),
 419                                    addr);
 420 }
 421
 422 #ifdef CONFIG_PROC_FS
 423 struct ac6_iter_state {
 424         struct seq_net_private p;
 425         struct net_device *dev;
 426         struct inet6_dev *idev;
 427 };
 428
 429 #define ac6_seq_private(seq)    ((struct ac6_iter_state *)(seq)->private)
 430
 431 static inline struct ifacaddr6 *ac6_get_first(struct seq_file *seq)
 432 {
 433         struct ifacaddr6 *im = NULL;
 434         struct ac6_iter_state *state = ac6_seq_private(seq);
 435         struct net *net = seq_file_net(seq);
 436
 437         state->idev = NULL;
 438         for_each_netdev_rcu(net, state->dev) {
 439                 struct inet6_dev *idev;
 440                 idev = __in6_dev_get(state->dev);
 441                 if (!idev)
 442                         continue;
 443                 read_lock_bh(&idev->lock);
 444                 im = idev->ac_list;
 445                 if (im) {
 446                         state->idev = idev;
 447                         break;
 448                 }
 449                 read_unlock_bh(&idev->lock);
 450         }
 451         return im;
 452 }
 453
 454 static struct ifacaddr6 *ac6_get_next(struct seq_file *seq, struct ifacaddr6 *im)
 455 {
 456         struct ac6_iter_state *state = ac6_seq_private(seq);
 457
 458         im = im->aca_next;
 459         while (!im) {
 460                 if (likely(state->idev != NULL))
 461                         read_unlock_bh(&state->idev->lock);
 462
 463                 state->dev = next_net_device_rcu(state->dev);
 464                 if (!state->dev) {
 465                         state->idev = NULL;
 466                         break;
 467                 }
 468                 state->idev = __in6_dev_get(state->dev);
 469                 if (!state->idev)
 470                         continue;
 471                 read_lock_bh(&state->idev->lock);
 472                 im = state->idev->ac_list;
 473         }
 474         return im;
 475 }
 476
 477 static struct ifacaddr6 *ac6_get_idx(struct seq_file *seq, loff_t pos)
 478 {
 479         struct ifacaddr6 *im = ac6_get_first(seq);
 480         if (im)
 481                 while (pos && (im = ac6_get_next(seq, im)) != NULL)
 482                         --pos;
 483         return pos ? NULL : im;
 484 }
 485
 486 static void *ac6_seq_start(struct seq_file *seq, loff_t *pos)
 487         __acquires(RCU)
 488 {
 489         rcu_read_lock();
 490         return ac6_get_idx(seq, *pos);
 491 }
 492
 493 static void *ac6_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 494 {
 495         struct ifacaddr6 *im = ac6_get_next(seq, v);
 496
 497         ++*pos;
 498         return im;
 499 }
 500
 501 static void ac6_seq_stop(struct seq_file *seq, void *v)
 502         __releases(RCU)
 503 {
 504         struct ac6_iter_state *state = ac6_seq_private(seq);
 505
 506         if (likely(state->idev != NULL)) {
 507                 read_unlock_bh(&state->idev->lock);
 508                 state->idev = NULL;
 509         }
 510         rcu_read_unlock();
 511 }
 512
 513 static int ac6_seq_show(struct seq_file *seq, void *v)
 514 {
 515         struct ifacaddr6 *im = (struct ifacaddr6 *)v;
 516         struct ac6_iter_state *state = ac6_seq_private(seq);
 517
 518         seq_printf(seq, "%-4d %-15s %pi6 %5d\n",
 519                    state->dev->ifindex, state->dev->name,
 520                    &im->aca_addr, im->aca_users);
 521         return 0;
 522 }
 523
 524 static const struct seq_operations ac6_seq_ops = {
 525         .start  =       ac6_seq_start,
 526         .next   =       ac6_seq_next,
 527         .stop   =       ac6_seq_stop,
 528         .show   =       ac6_seq_show,
 529 };
 530
 531 static int ac6_seq_open(struct inode *inode, struct file *file)
 532 {
 533         return seq_open_net(inode, file, &ac6_seq_ops,
 534                             sizeof(struct ac6_iter_state));
 535 }
 536
 537 static const struct file_operations ac6_seq_fops = {
 538         .owner          =       THIS_MODULE,
 539         .open           =       ac6_seq_open,
 540         .read           =       seq_read,
 541         .llseek         =       seq_lseek,
 542         .release        =       seq_release_net,
 543 };
 544
 545 int __net_init ac6_proc_init(struct net *net)
 546 {
 547         if (!proc_create("anycast6", S_IRUGO, net->proc_net, &ac6_seq_fops))
 548                 return -ENOMEM;
 549
 550         return 0;
 551 }
 552
 553 void ac6_proc_exit(struct net *net)
 554 {
 555         remove_proc_entry("anycast6", net->proc_net);
 556 }
 557 #endif
 558