linux/net/ipv6/anycast.c
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   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
  47static int ipv6_dev_ac_dec(struct net_device *dev, struct in6_addr *addr);
  48
  49/* Big ac list lock for all the sockets */
  50static DEFINE_RWLOCK(ipv6_sk_ac_lock);
  51
  52
  53/*
  54 *      socket join an anycast group
  55 */
  56
  57int ipv6_sock_ac_join(struct sock *sk, int ifindex, 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        ipv6_addr_copy(&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->rt6i_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
 138error:
 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 */
 148int ipv6_sock_ac_drop(struct sock *sk, int ifindex, 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
 184void 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
 221int 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
 243static 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 */
 255int ipv6_dev_ac_inc(struct net_device *dev, 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, 1);
 293        if (IS_ERR(rt)) {
 294                kfree(aca);
 295                err = PTR_ERR(rt);
 296                goto out;
 297        }
 298
 299        ipv6_addr_copy(&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;
 318out:
 319        write_unlock_bh(&idev->lock);
 320        in6_dev_put(idev);
 321        return err;
 322}
 323
 324/*
 325 *      device anycast group decrement
 326 */
 327int __ipv6_dev_ac_dec(struct inet6_dev *idev, 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() */
 361static int ipv6_dev_ac_dec(struct net_device *dev, 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 */
 374static int ipv6_chk_acast_dev(struct net_device *dev, 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 */
 394int ipv6_chk_acast_addr(struct net *net, struct net_device *dev,
 395                        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
 414struct 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
 422static 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
 445static 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
 468static 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
 477static 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
 484static 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
 492static 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
 504static 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
 515static 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
 522static 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
 528static 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
 536int __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
 544void ac6_proc_exit(struct net *net)
 545{
 546        proc_net_remove(net, "anycast6");
 547}
 548#endif
 549
 550