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         ASSERT_RTNL();
  64
  65         if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
  66                 return -EPERM;
  67         if (ipv6_addr_is_multicast(addr))
  68                 return -EINVAL;
  69
  70         if (ifindex)
  71                 dev = __dev_get_by_index(net, ifindex);
  72
  73         if (ipv6_chk_addr_and_flags(net, addr, dev, true, 0, IFA_F_TENTATIVE))
  74                 return -EINVAL;
  75
  76         pac = sock_kmalloc(sk, sizeof(struct ipv6_ac_socklist), GFP_KERNEL);
  77         if (!pac)
  78                 return -ENOMEM;
  79         pac->acl_next = NULL;
  80         pac->acl_addr = *addr;
  81
  82         if (ifindex == 0) {
  83                 struct rt6_info *rt;
  84
  85                 rt = rt6_lookup(net, addr, NULL, 0, NULL, 0);
  86                 if (rt) {
  87                         dev = rt->dst.dev;
  88                         ip6_rt_put(rt);
  89                 } else if (ishost) {
  90                         err = -EADDRNOTAVAIL;
  91                         goto error;
  92                 } else {
  93                         /* router, no matching interface: just pick one */
  94                         dev = __dev_get_by_flags(net, IFF_UP,
  95                                                  IFF_UP | IFF_LOOPBACK);
  96                 }
  97         }
  98
  99         if (!dev) {
 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(idev, addr);
 130         if (!err) {
 131                 pac->acl_next = np->ipv6_ac_list;
 132                 np->ipv6_ac_list = pac;
 133                 pac = NULL;
 134         }
 135
 136 error:
 137         if (pac)
 138                 sock_kfree_s(sk, pac, sizeof(*pac));
 139         return err;
 140 }
 141
 142 /*
 143  *      socket leave an anycast group
 144  */
 145 int ipv6_sock_ac_drop(struct sock *sk, int ifindex, const struct in6_addr *addr)
 146 {
 147         struct ipv6_pinfo *np = inet6_sk(sk);
 148         struct net_device *dev;
 149         struct ipv6_ac_socklist *pac, *prev_pac;
 150         struct net *net = sock_net(sk);
 151
 152         ASSERT_RTNL();
 153
 154         prev_pac = NULL;
 155         for (pac = np->ipv6_ac_list; pac; pac = pac->acl_next) {
 156                 if ((ifindex == 0 || pac->acl_ifindex == ifindex) &&
 157                      ipv6_addr_equal(&pac->acl_addr, addr))
 158                         break;
 159                 prev_pac = pac;
 160         }
 161         if (!pac)
 162                 return -ENOENT;
 163         if (prev_pac)
 164                 prev_pac->acl_next = pac->acl_next;
 165         else
 166                 np->ipv6_ac_list = pac->acl_next;
 167
 168         dev = __dev_get_by_index(net, pac->acl_ifindex);
 169         if (dev)
 170                 ipv6_dev_ac_dec(dev, &pac->acl_addr);
 171
 172         sock_kfree_s(sk, pac, sizeof(*pac));
 173         return 0;
 174 }
 175
 176 void ipv6_sock_ac_close(struct sock *sk)
 177 {
 178         struct ipv6_pinfo *np = inet6_sk(sk);
 179         struct net_device *dev = NULL;
 180         struct ipv6_ac_socklist *pac;
 181         struct net *net = sock_net(sk);
 182         int     prev_index;
 183
 184         if (!np->ipv6_ac_list)
 185                 return;
 186
 187         rtnl_lock();
 188         pac = np->ipv6_ac_list;
 189         np->ipv6_ac_list = NULL;
 190
 191         prev_index = 0;
 192         while (pac) {
 193                 struct ipv6_ac_socklist *next = pac->acl_next;
 194
 195                 if (pac->acl_ifindex != prev_index) {
 196                         dev = __dev_get_by_index(net, pac->acl_ifindex);
 197                         prev_index = pac->acl_ifindex;
 198                 }
 199                 if (dev)
 200                         ipv6_dev_ac_dec(dev, &pac->acl_addr);
 201                 sock_kfree_s(sk, pac, sizeof(*pac));
 202                 pac = next;
 203         }
 204         rtnl_unlock();
 205 }
 206
 207 static void aca_get(struct ifacaddr6 *aca)
 208 {
 209         refcount_inc(&aca->aca_refcnt);
 210 }
 211
 212 static void aca_put(struct ifacaddr6 *ac)
 213 {
 214         if (refcount_dec_and_test(&ac->aca_refcnt)) {
 215                 fib6_info_release(ac->aca_rt);
 216                 kfree(ac);
 217         }
 218 }
 219
 220 static struct ifacaddr6 *aca_alloc(struct fib6_info *f6i,
 221                                    const struct in6_addr *addr)
 222 {
 223         struct ifacaddr6 *aca;
 224
 225         aca = kzalloc(sizeof(*aca), GFP_ATOMIC);
 226         if (!aca)
 227                 return NULL;
 228
 229         aca->aca_addr = *addr;
 230         fib6_info_hold(f6i);
 231         aca->aca_rt = f6i;
 232         aca->aca_users = 1;
 233         /* aca_tstamp should be updated upon changes */
 234         aca->aca_cstamp = aca->aca_tstamp = jiffies;
 235         refcount_set(&aca->aca_refcnt, 1);
 236
 237         return aca;
 238 }
 239
 240 /*
 241  *      device anycast group inc (add if not found)
 242  */
 243 int __ipv6_dev_ac_inc(struct inet6_dev *idev, const struct in6_addr *addr)
 244 {
 245         struct ifacaddr6 *aca;
 246         struct fib6_info *f6i;
 247         struct net *net;
 248         int err;
 249
 250         ASSERT_RTNL();
 251
 252         write_lock_bh(&idev->lock);
 253         if (idev->dead) {
 254                 err = -ENODEV;
 255                 goto out;
 256         }
 257
 258         for (aca = idev->ac_list; aca; aca = aca->aca_next) {
 259                 if (ipv6_addr_equal(&aca->aca_addr, addr)) {
 260                         aca->aca_users++;
 261                         err = 0;
 262                         goto out;
 263                 }
 264         }
 265
 266         net = dev_net(idev->dev);
 267         f6i = addrconf_f6i_alloc(net, idev, addr, true, GFP_ATOMIC);
 268         if (IS_ERR(f6i)) {
 269                 err = PTR_ERR(f6i);
 270                 goto out;
 271         }
 272         aca = aca_alloc(f6i, addr);
 273         if (!aca) {
 274                 fib6_info_release(f6i);
 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(net, f6i);
 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         ip6_del_rt(dev_net(idev->dev), aca->aca_rt);
 331
 332         aca_put(aca);
 333         return 0;
 334 }
 335
 336 /* called with rtnl_lock() */
 337 static int ipv6_dev_ac_dec(struct net_device *dev, const struct in6_addr *addr)
 338 {
 339         struct inet6_dev *idev = __in6_dev_get(dev);
 340
 341         if (!idev)
 342                 return -ENODEV;
 343         return __ipv6_dev_ac_dec(idev, addr);
 344 }
 345
 346 void ipv6_ac_destroy_dev(struct inet6_dev *idev)
 347 {
 348         struct ifacaddr6 *aca;
 349
 350         write_lock_bh(&idev->lock);
 351         while ((aca = idev->ac_list) != NULL) {
 352                 idev->ac_list = aca->aca_next;
 353                 write_unlock_bh(&idev->lock);
 354
 355                 addrconf_leave_solict(idev, &aca->aca_addr);
 356
 357                 ip6_del_rt(dev_net(idev->dev), aca->aca_rt);
 358
 359                 aca_put(aca);
 360
 361                 write_lock_bh(&idev->lock);
 362         }
 363         write_unlock_bh(&idev->lock);
 364 }
 365
 366 /*
 367  *      check if the interface has this anycast address
 368  *      called with rcu_read_lock()
 369  */
 370 static bool ipv6_chk_acast_dev(struct net_device *dev, const struct in6_addr *addr)
 371 {
 372         struct inet6_dev *idev;
 373         struct ifacaddr6 *aca;
 374
 375         idev = __in6_dev_get(dev);
 376         if (idev) {
 377                 read_lock_bh(&idev->lock);
 378                 for (aca = idev->ac_list; aca; aca = aca->aca_next)
 379                         if (ipv6_addr_equal(&aca->aca_addr, addr))
 380                                 break;
 381                 read_unlock_bh(&idev->lock);
 382                 return aca != NULL;
 383         }
 384         return false;
 385 }
 386
 387 /*
 388  *      check if given interface (or any, if dev==0) has this anycast address
 389  */
 390 bool ipv6_chk_acast_addr(struct net *net, struct net_device *dev,
 391                          const struct in6_addr *addr)
 392 {
 393         bool found = false;
 394
 395         rcu_read_lock();
 396         if (dev)
 397                 found = ipv6_chk_acast_dev(dev, addr);
 398         else
 399                 for_each_netdev_rcu(net, dev)
 400                         if (ipv6_chk_acast_dev(dev, addr)) {
 401                                 found = true;
 402                                 break;
 403                         }
 404         rcu_read_unlock();
 405         return found;
 406 }
 407
 408 /*      check if this anycast address is link-local on given interface or
 409  *      is global
 410  */
 411 bool ipv6_chk_acast_addr_src(struct net *net, struct net_device *dev,
 412                              const struct in6_addr *addr)
 413 {
 414         return ipv6_chk_acast_addr(net,
 415                                    (ipv6_addr_type(addr) & IPV6_ADDR_LINKLOCAL ?
 416                                     dev : NULL),
 417                                    addr);
 418 }
 419
 420 #ifdef CONFIG_PROC_FS
 421 struct ac6_iter_state {
 422         struct seq_net_private p;
 423         struct net_device *dev;
 424         struct inet6_dev *idev;
 425 };
 426
 427 #define ac6_seq_private(seq)    ((struct ac6_iter_state *)(seq)->private)
 428
 429 static inline struct ifacaddr6 *ac6_get_first(struct seq_file *seq)
 430 {
 431         struct ifacaddr6 *im = NULL;
 432         struct ac6_iter_state *state = ac6_seq_private(seq);
 433         struct net *net = seq_file_net(seq);
 434
 435         state->idev = NULL;
 436         for_each_netdev_rcu(net, state->dev) {
 437                 struct inet6_dev *idev;
 438                 idev = __in6_dev_get(state->dev);
 439                 if (!idev)
 440                         continue;
 441                 read_lock_bh(&idev->lock);
 442                 im = idev->ac_list;
 443                 if (im) {
 444                         state->idev = idev;
 445                         break;
 446                 }
 447                 read_unlock_bh(&idev->lock);
 448         }
 449         return im;
 450 }
 451
 452 static struct ifacaddr6 *ac6_get_next(struct seq_file *seq, struct ifacaddr6 *im)
 453 {
 454         struct ac6_iter_state *state = ac6_seq_private(seq);
 455
 456         im = im->aca_next;
 457         while (!im) {
 458                 if (likely(state->idev != NULL))
 459                         read_unlock_bh(&state->idev->lock);
 460
 461                 state->dev = next_net_device_rcu(state->dev);
 462                 if (!state->dev) {
 463                         state->idev = NULL;
 464                         break;
 465                 }
 466                 state->idev = __in6_dev_get(state->dev);
 467                 if (!state->idev)
 468                         continue;
 469                 read_lock_bh(&state->idev->lock);
 470                 im = state->idev->ac_list;
 471         }
 472         return im;
 473 }
 474
 475 static struct ifacaddr6 *ac6_get_idx(struct seq_file *seq, loff_t pos)
 476 {
 477         struct ifacaddr6 *im = ac6_get_first(seq);
 478         if (im)
 479                 while (pos && (im = ac6_get_next(seq, im)) != NULL)
 480                         --pos;
 481         return pos ? NULL : im;
 482 }
 483
 484 static void *ac6_seq_start(struct seq_file *seq, loff_t *pos)
 485         __acquires(RCU)
 486 {
 487         rcu_read_lock();
 488         return ac6_get_idx(seq, *pos);
 489 }
 490
 491 static void *ac6_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 492 {
 493         struct ifacaddr6 *im = ac6_get_next(seq, v);
 494
 495         ++*pos;
 496         return im;
 497 }
 498
 499 static void ac6_seq_stop(struct seq_file *seq, void *v)
 500         __releases(RCU)
 501 {
 502         struct ac6_iter_state *state = ac6_seq_private(seq);
 503
 504         if (likely(state->idev != NULL)) {
 505                 read_unlock_bh(&state->idev->lock);
 506                 state->idev = NULL;
 507         }
 508         rcu_read_unlock();
 509 }
 510
 511 static int ac6_seq_show(struct seq_file *seq, void *v)
 512 {
 513         struct ifacaddr6 *im = (struct ifacaddr6 *)v;
 514         struct ac6_iter_state *state = ac6_seq_private(seq);
 515
 516         seq_printf(seq, "%-4d %-15s %pi6 %5d\n",
 517                    state->dev->ifindex, state->dev->name,
 518                    &im->aca_addr, im->aca_users);
 519         return 0;
 520 }
 521
 522 static const struct seq_operations ac6_seq_ops = {
 523         .start  =       ac6_seq_start,
 524         .next   =       ac6_seq_next,
 525         .stop   =       ac6_seq_stop,
 526         .show   =       ac6_seq_show,
 527 };
 528
 529 int __net_init ac6_proc_init(struct net *net)
 530 {
 531         if (!proc_create_net("anycast6", 0444, net->proc_net, &ac6_seq_ops,
 532                         sizeof(struct ac6_iter_state)))
 533                 return -ENOMEM;
 534
 535         return 0;
 536 }
 537
 538 void ac6_proc_exit(struct net *net)
 539 {
 540         remove_proc_entry("anycast6", net->proc_net);
 541 }
 542 #endif