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 #if 0
 215 /* The function is not used, which is funny. Apparently, author
 216  * supposed to use it to filter out datagrams inside udp/raw but forgot.
 217  *
 218  * It is OK, anycasts are not special comparing to delivery to unicasts.
 219  */
 220
 221 int inet6_ac_check(struct sock *sk, struct in6_addr *addr, int ifindex)
 222 {
 223         struct ipv6_ac_socklist *pac;
 224         struct ipv6_pinfo *np = inet6_sk(sk);
 225         int     found;
 226
 227         found = 0;
 228         read_lock(&ipv6_sk_ac_lock);
 229         for (pac=np->ipv6_ac_list; pac; pac=pac->acl_next) {
 230                 if (ifindex && pac->acl_ifindex != ifindex)
 231                         continue;
 232                 found = ipv6_addr_equal(&pac->acl_addr, addr);
 233                 if (found)
 234                         break;
 235         }
 236         read_unlock(&ipv6_sk_ac_lock);
 237
 238         return found;
 239 }
 240
 241 #endif
 242
 243 static void aca_put(struct ifacaddr6 *ac)
 244 {
 245         if (atomic_dec_and_test(&ac->aca_refcnt)) {
 246                 in6_dev_put(ac->aca_idev);
 247                 dst_release(&ac->aca_rt->dst);
 248                 kfree(ac);
 249         }
 250 }
 251
 252 /*
 253  *      device anycast group inc (add if not found)
 254  */
 255 int ipv6_dev_ac_inc(struct net_device *dev, const struct in6_addr *addr)
 256 {
 257         struct ifacaddr6 *aca;
 258         struct inet6_dev *idev;
 259         struct rt6_info *rt;
 260         int err;
 261
 262         idev = in6_dev_get(dev);
 263
 264         if (idev == NULL)
 265                 return -EINVAL;
 266
 267         write_lock_bh(&idev->lock);
 268         if (idev->dead) {
 269                 err = -ENODEV;
 270                 goto out;
 271         }
 272
 273         for (aca = idev->ac_list; aca; aca = aca->aca_next) {
 274                 if (ipv6_addr_equal(&aca->aca_addr, addr)) {
 275                         aca->aca_users++;
 276                         err = 0;
 277                         goto out;
 278                 }
 279         }
 280
 281         /*
 282          *      not found: create a new one.
 283          */
 284
 285         aca = kzalloc(sizeof(struct ifacaddr6), GFP_ATOMIC);
 286
 287         if (aca == NULL) {
 288                 err = -ENOMEM;
 289                 goto out;
 290         }
 291
 292         rt = addrconf_dst_alloc(idev, addr, true);
 293         if (IS_ERR(rt)) {
 294                 kfree(aca);
 295                 err = PTR_ERR(rt);
 296                 goto out;
 297         }
 298
 299         aca->aca_addr = *addr;
 300         aca->aca_idev = idev;
 301         aca->aca_rt = rt;
 302         aca->aca_users = 1;
 303         /* aca_tstamp should be updated upon changes */
 304         aca->aca_cstamp = aca->aca_tstamp = jiffies;
 305         atomic_set(&aca->aca_refcnt, 2);
 306         spin_lock_init(&aca->aca_lock);
 307
 308         aca->aca_next = idev->ac_list;
 309         idev->ac_list = aca;
 310         write_unlock_bh(&idev->lock);
 311
 312         ip6_ins_rt(rt);
 313
 314         addrconf_join_solict(dev, &aca->aca_addr);
 315
 316         aca_put(aca);
 317         return 0;
 318 out:
 319         write_unlock_bh(&idev->lock);
 320         in6_dev_put(idev);
 321         return err;
 322 }
 323
 324 /*
 325  *      device anycast group decrement
 326  */
 327 int __ipv6_dev_ac_dec(struct inet6_dev *idev, const struct in6_addr *addr)
 328 {
 329         struct ifacaddr6 *aca, *prev_aca;
 330
 331         write_lock_bh(&idev->lock);
 332         prev_aca = NULL;
 333         for (aca = idev->ac_list; aca; aca = aca->aca_next) {
 334                 if (ipv6_addr_equal(&aca->aca_addr, addr))
 335                         break;
 336                 prev_aca = aca;
 337         }
 338         if (!aca) {
 339                 write_unlock_bh(&idev->lock);
 340                 return -ENOENT;
 341         }
 342         if (--aca->aca_users > 0) {
 343                 write_unlock_bh(&idev->lock);
 344                 return 0;
 345         }
 346         if (prev_aca)
 347                 prev_aca->aca_next = aca->aca_next;
 348         else
 349                 idev->ac_list = aca->aca_next;
 350         write_unlock_bh(&idev->lock);
 351         addrconf_leave_solict(idev, &aca->aca_addr);
 352
 353         dst_hold(&aca->aca_rt->dst);
 354         ip6_del_rt(aca->aca_rt);
 355
 356         aca_put(aca);
 357         return 0;
 358 }
 359
 360 /* called with rcu_read_lock() */
 361 static int ipv6_dev_ac_dec(struct net_device *dev, const struct in6_addr *addr)
 362 {
 363         struct inet6_dev *idev = __in6_dev_get(dev);
 364
 365         if (idev == NULL)
 366                 return -ENODEV;
 367         return __ipv6_dev_ac_dec(idev, addr);
 368 }
 369
 370 /*
 371  *      check if the interface has this anycast address
 372  *      called with rcu_read_lock()
 373  */
 374 static int ipv6_chk_acast_dev(struct net_device *dev, const struct in6_addr *addr)
 375 {
 376         struct inet6_dev *idev;
 377         struct ifacaddr6 *aca;
 378
 379         idev = __in6_dev_get(dev);
 380         if (idev) {
 381                 read_lock_bh(&idev->lock);
 382                 for (aca = idev->ac_list; aca; aca = aca->aca_next)
 383                         if (ipv6_addr_equal(&aca->aca_addr, addr))
 384                                 break;
 385                 read_unlock_bh(&idev->lock);
 386                 return aca != NULL;
 387         }
 388         return 0;
 389 }
 390
 391 /*
 392  *      check if given interface (or any, if dev==0) has this anycast address
 393  */
 394 int ipv6_chk_acast_addr(struct net *net, struct net_device *dev,
 395                         const struct in6_addr *addr)
 396 {
 397         int found = 0;
 398
 399         rcu_read_lock();
 400         if (dev)
 401                 found = ipv6_chk_acast_dev(dev, addr);
 402         else
 403                 for_each_netdev_rcu(net, dev)
 404                         if (ipv6_chk_acast_dev(dev, addr)) {
 405                                 found = 1;
 406                                 break;
 407                         }
 408         rcu_read_unlock();
 409         return found;
 410 }
 411
 412
 413 #ifdef CONFIG_PROC_FS
 414 struct ac6_iter_state {
 415         struct seq_net_private p;
 416         struct net_device *dev;
 417         struct inet6_dev *idev;
 418 };
 419
 420 #define ac6_seq_private(seq)    ((struct ac6_iter_state *)(seq)->private)
 421
 422 static inline struct ifacaddr6 *ac6_get_first(struct seq_file *seq)
 423 {
 424         struct ifacaddr6 *im = NULL;
 425         struct ac6_iter_state *state = ac6_seq_private(seq);
 426         struct net *net = seq_file_net(seq);
 427
 428         state->idev = NULL;
 429         for_each_netdev_rcu(net, state->dev) {
 430                 struct inet6_dev *idev;
 431                 idev = __in6_dev_get(state->dev);
 432                 if (!idev)
 433                         continue;
 434                 read_lock_bh(&idev->lock);
 435                 im = idev->ac_list;
 436                 if (im) {
 437                         state->idev = idev;
 438                         break;
 439                 }
 440                 read_unlock_bh(&idev->lock);
 441         }
 442         return im;
 443 }
 444
 445 static struct ifacaddr6 *ac6_get_next(struct seq_file *seq, struct ifacaddr6 *im)
 446 {
 447         struct ac6_iter_state *state = ac6_seq_private(seq);
 448
 449         im = im->aca_next;
 450         while (!im) {
 451                 if (likely(state->idev != NULL))
 452                         read_unlock_bh(&state->idev->lock);
 453
 454                 state->dev = next_net_device_rcu(state->dev);
 455                 if (!state->dev) {
 456                         state->idev = NULL;
 457                         break;
 458                 }
 459                 state->idev = __in6_dev_get(state->dev);
 460                 if (!state->idev)
 461                         continue;
 462                 read_lock_bh(&state->idev->lock);
 463                 im = state->idev->ac_list;
 464         }
 465         return im;
 466 }
 467
 468 static struct ifacaddr6 *ac6_get_idx(struct seq_file *seq, loff_t pos)
 469 {
 470         struct ifacaddr6 *im = ac6_get_first(seq);
 471         if (im)
 472                 while (pos && (im = ac6_get_next(seq, im)) != NULL)
 473                         --pos;
 474         return pos ? NULL : im;
 475 }
 476
 477 static void *ac6_seq_start(struct seq_file *seq, loff_t *pos)
 478         __acquires(RCU)
 479 {
 480         rcu_read_lock();
 481         return ac6_get_idx(seq, *pos);
 482 }
 483
 484 static void *ac6_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 485 {
 486         struct ifacaddr6 *im = ac6_get_next(seq, v);
 487
 488         ++*pos;
 489         return im;
 490 }
 491
 492 static void ac6_seq_stop(struct seq_file *seq, void *v)
 493         __releases(RCU)
 494 {
 495         struct ac6_iter_state *state = ac6_seq_private(seq);
 496
 497         if (likely(state->idev != NULL)) {
 498                 read_unlock_bh(&state->idev->lock);
 499                 state->idev = NULL;
 500         }
 501         rcu_read_unlock();
 502 }
 503
 504 static int ac6_seq_show(struct seq_file *seq, void *v)
 505 {
 506         struct ifacaddr6 *im = (struct ifacaddr6 *)v;
 507         struct ac6_iter_state *state = ac6_seq_private(seq);
 508
 509         seq_printf(seq, "%-4d %-15s %pi6 %5d\n",
 510                    state->dev->ifindex, state->dev->name,
 511                    &im->aca_addr, im->aca_users);
 512         return 0;
 513 }
 514
 515 static const struct seq_operations ac6_seq_ops = {
 516         .start  =       ac6_seq_start,
 517         .next   =       ac6_seq_next,
 518         .stop   =       ac6_seq_stop,
 519         .show   =       ac6_seq_show,
 520 };
 521
 522 static int ac6_seq_open(struct inode *inode, struct file *file)
 523 {
 524         return seq_open_net(inode, file, &ac6_seq_ops,
 525                             sizeof(struct ac6_iter_state));
 526 }
 527
 528 static const struct file_operations ac6_seq_fops = {
 529         .owner          =       THIS_MODULE,
 530         .open           =       ac6_seq_open,
 531         .read           =       seq_read,
 532         .llseek         =       seq_lseek,
 533         .release        =       seq_release_net,
 534 };
 535
 536 int __net_init ac6_proc_init(struct net *net)
 537 {
 538         if (!proc_net_fops_create(net, "anycast6", S_IRUGO, &ac6_seq_fops))
 539                 return -ENOMEM;
 540
 541         return 0;
 542 }
 543
 544 void ac6_proc_exit(struct net *net)
 545 {
 546         proc_net_remove(net, "anycast6");
 547 }
 548 #endif
 549