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         spin_lock_init(&aca->aca_lock);
 239
 240         return aca;
 241 }
 242
 243 /*
 244  *      device anycast group inc (add if not found)
 245  */
 246 int __ipv6_dev_ac_inc(struct inet6_dev *idev, const struct in6_addr *addr)
 247 {
 248         struct ifacaddr6 *aca;
 249         struct rt6_info *rt;
 250         int err;
 251
 252         ASSERT_RTNL();
 253
 254         write_lock_bh(&idev->lock);
 255         if (idev->dead) {
 256                 err = -ENODEV;
 257                 goto out;
 258         }
 259
 260         for (aca = idev->ac_list; aca; aca = aca->aca_next) {
 261                 if (ipv6_addr_equal(&aca->aca_addr, addr)) {
 262                         aca->aca_users++;
 263                         err = 0;
 264                         goto out;
 265                 }
 266         }
 267
 268         rt = addrconf_dst_alloc(idev, addr, true);
 269         if (IS_ERR(rt)) {
 270                 err = PTR_ERR(rt);
 271                 goto out;
 272         }
 273         aca = aca_alloc(rt, addr);
 274         if (aca == NULL) {
 275                 ip6_rt_put(rt);
 276                 err = -ENOMEM;
 277                 goto out;
 278         }
 279
 280         aca->aca_next = idev->ac_list;
 281         idev->ac_list = aca;
 282
 283         /* Hold this for addrconf_join_solict() below before we unlock,
 284          * it is already exposed via idev->ac_list.
 285          */
 286         aca_get(aca);
 287         write_unlock_bh(&idev->lock);
 288
 289         ip6_ins_rt(rt);
 290
 291         addrconf_join_solict(idev->dev, &aca->aca_addr);
 292
 293         aca_put(aca);
 294         return 0;
 295 out:
 296         write_unlock_bh(&idev->lock);
 297         return err;
 298 }
 299
 300 /*
 301  *      device anycast group decrement
 302  */
 303 int __ipv6_dev_ac_dec(struct inet6_dev *idev, const struct in6_addr *addr)
 304 {
 305         struct ifacaddr6 *aca, *prev_aca;
 306
 307         ASSERT_RTNL();
 308
 309         write_lock_bh(&idev->lock);
 310         prev_aca = NULL;
 311         for (aca = idev->ac_list; aca; aca = aca->aca_next) {
 312                 if (ipv6_addr_equal(&aca->aca_addr, addr))
 313                         break;
 314                 prev_aca = aca;
 315         }
 316         if (!aca) {
 317                 write_unlock_bh(&idev->lock);
 318                 return -ENOENT;
 319         }
 320         if (--aca->aca_users > 0) {
 321                 write_unlock_bh(&idev->lock);
 322                 return 0;
 323         }
 324         if (prev_aca)
 325                 prev_aca->aca_next = aca->aca_next;
 326         else
 327                 idev->ac_list = aca->aca_next;
 328         write_unlock_bh(&idev->lock);
 329         addrconf_leave_solict(idev, &aca->aca_addr);
 330
 331         dst_hold(&aca->aca_rt->dst);
 332         ip6_del_rt(aca->aca_rt);
 333
 334         aca_put(aca);
 335         return 0;
 336 }
 337
 338 /* called with rtnl_lock() */
 339 static int ipv6_dev_ac_dec(struct net_device *dev, const struct in6_addr *addr)
 340 {
 341         struct inet6_dev *idev = __in6_dev_get(dev);
 342
 343         if (idev == NULL)
 344                 return -ENODEV;
 345         return __ipv6_dev_ac_dec(idev, addr);
 346 }
 347
 348 void ipv6_ac_destroy_dev(struct inet6_dev *idev)
 349 {
 350         struct ifacaddr6 *aca;
 351
 352         write_lock_bh(&idev->lock);
 353         while ((aca = idev->ac_list) != NULL) {
 354                 idev->ac_list = aca->aca_next;
 355                 write_unlock_bh(&idev->lock);
 356
 357                 addrconf_leave_solict(idev, &aca->aca_addr);
 358
 359                 dst_hold(&aca->aca_rt->dst);
 360                 ip6_del_rt(aca->aca_rt);
 361
 362                 aca_put(aca);
 363
 364                 write_lock_bh(&idev->lock);
 365         }
 366         write_unlock_bh(&idev->lock);
 367 }
 368
 369 /*
 370  *      check if the interface has this anycast address
 371  *      called with rcu_read_lock()
 372  */
 373 static bool ipv6_chk_acast_dev(struct net_device *dev, const struct in6_addr *addr)
 374 {
 375         struct inet6_dev *idev;
 376         struct ifacaddr6 *aca;
 377
 378         idev = __in6_dev_get(dev);
 379         if (idev) {
 380                 read_lock_bh(&idev->lock);
 381                 for (aca = idev->ac_list; aca; aca = aca->aca_next)
 382                         if (ipv6_addr_equal(&aca->aca_addr, addr))
 383                                 break;
 384                 read_unlock_bh(&idev->lock);
 385                 return aca != NULL;
 386         }
 387         return false;
 388 }
 389
 390 /*
 391  *      check if given interface (or any, if dev==0) has this anycast address
 392  */
 393 bool ipv6_chk_acast_addr(struct net *net, struct net_device *dev,
 394                          const struct in6_addr *addr)
 395 {
 396         bool found = false;
 397
 398         rcu_read_lock();
 399         if (dev)
 400                 found = ipv6_chk_acast_dev(dev, addr);
 401         else
 402                 for_each_netdev_rcu(net, dev)
 403                         if (ipv6_chk_acast_dev(dev, addr)) {
 404                                 found = true;
 405                                 break;
 406                         }
 407         rcu_read_unlock();
 408         return found;
 409 }
 410
 411 /*      check if this anycast address is link-local on given interface or
 412  *      is global
 413  */
 414 bool ipv6_chk_acast_addr_src(struct net *net, struct net_device *dev,
 415                              const struct in6_addr *addr)
 416 {
 417         return ipv6_chk_acast_addr(net,
 418                                    (ipv6_addr_type(addr) & IPV6_ADDR_LINKLOCAL ?
 419                                     dev : NULL),
 420                                    addr);
 421 }
 422
 423 #ifdef CONFIG_PROC_FS
 424 struct ac6_iter_state {
 425         struct seq_net_private p;
 426         struct net_device *dev;
 427         struct inet6_dev *idev;
 428 };
 429
 430 #define ac6_seq_private(seq)    ((struct ac6_iter_state *)(seq)->private)
 431
 432 static inline struct ifacaddr6 *ac6_get_first(struct seq_file *seq)
 433 {
 434         struct ifacaddr6 *im = NULL;
 435         struct ac6_iter_state *state = ac6_seq_private(seq);
 436         struct net *net = seq_file_net(seq);
 437
 438         state->idev = NULL;
 439         for_each_netdev_rcu(net, state->dev) {
 440                 struct inet6_dev *idev;
 441                 idev = __in6_dev_get(state->dev);
 442                 if (!idev)
 443                         continue;
 444                 read_lock_bh(&idev->lock);
 445                 im = idev->ac_list;
 446                 if (im) {
 447                         state->idev = idev;
 448                         break;
 449                 }
 450                 read_unlock_bh(&idev->lock);
 451         }
 452         return im;
 453 }
 454
 455 static struct ifacaddr6 *ac6_get_next(struct seq_file *seq, struct ifacaddr6 *im)
 456 {
 457         struct ac6_iter_state *state = ac6_seq_private(seq);
 458
 459         im = im->aca_next;
 460         while (!im) {
 461                 if (likely(state->idev != NULL))
 462                         read_unlock_bh(&state->idev->lock);
 463
 464                 state->dev = next_net_device_rcu(state->dev);
 465                 if (!state->dev) {
 466                         state->idev = NULL;
 467                         break;
 468                 }
 469                 state->idev = __in6_dev_get(state->dev);
 470                 if (!state->idev)
 471                         continue;
 472                 read_lock_bh(&state->idev->lock);
 473                 im = state->idev->ac_list;
 474         }
 475         return im;
 476 }
 477
 478 static struct ifacaddr6 *ac6_get_idx(struct seq_file *seq, loff_t pos)
 479 {
 480         struct ifacaddr6 *im = ac6_get_first(seq);
 481         if (im)
 482                 while (pos && (im = ac6_get_next(seq, im)) != NULL)
 483                         --pos;
 484         return pos ? NULL : im;
 485 }
 486
 487 static void *ac6_seq_start(struct seq_file *seq, loff_t *pos)
 488         __acquires(RCU)
 489 {
 490         rcu_read_lock();
 491         return ac6_get_idx(seq, *pos);
 492 }
 493
 494 static void *ac6_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 495 {
 496         struct ifacaddr6 *im = ac6_get_next(seq, v);
 497
 498         ++*pos;
 499         return im;
 500 }
 501
 502 static void ac6_seq_stop(struct seq_file *seq, void *v)
 503         __releases(RCU)
 504 {
 505         struct ac6_iter_state *state = ac6_seq_private(seq);
 506
 507         if (likely(state->idev != NULL)) {
 508                 read_unlock_bh(&state->idev->lock);
 509                 state->idev = NULL;
 510         }
 511         rcu_read_unlock();
 512 }
 513
 514 static int ac6_seq_show(struct seq_file *seq, void *v)
 515 {
 516         struct ifacaddr6 *im = (struct ifacaddr6 *)v;
 517         struct ac6_iter_state *state = ac6_seq_private(seq);
 518
 519         seq_printf(seq, "%-4d %-15s %pi6 %5d\n",
 520                    state->dev->ifindex, state->dev->name,
 521                    &im->aca_addr, im->aca_users);
 522         return 0;
 523 }
 524
 525 static const struct seq_operations ac6_seq_ops = {
 526         .start  =       ac6_seq_start,
 527         .next   =       ac6_seq_next,
 528         .stop   =       ac6_seq_stop,
 529         .show   =       ac6_seq_show,
 530 };
 531
 532 static int ac6_seq_open(struct inode *inode, struct file *file)
 533 {
 534         return seq_open_net(inode, file, &ac6_seq_ops,
 535                             sizeof(struct ac6_iter_state));
 536 }
 537
 538 static const struct file_operations ac6_seq_fops = {
 539         .owner          =       THIS_MODULE,
 540         .open           =       ac6_seq_open,
 541         .read           =       seq_read,
 542         .llseek         =       seq_lseek,
 543         .release        =       seq_release_net,
 544 };
 545
 546 int __net_init ac6_proc_init(struct net *net)
 547 {
 548         if (!proc_create("anycast6", S_IRUGO, net->proc_net, &ac6_seq_fops))
 549                 return -ENOMEM;
 550
 551         return 0;
 552 }
 553
 554 void ac6_proc_exit(struct net *net)
 555 {
 556         remove_proc_entry("anycast6", net->proc_net);
 557 }
 558 #endif
 559