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