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
  33#include <net/net_namespace.h>
  34#include <net/sock.h>
  35#include <net/snmp.h>
  36
  37#include <net/ipv6.h>
  38#include <net/protocol.h>
  39#include <net/if_inet6.h>
  40#include <net/ndisc.h>
  41#include <net/addrconf.h>
  42#include <net/ip6_route.h>
  43
  44#include <net/checksum.h>
  45
  46static int ipv6_dev_ac_dec(struct net_device *dev, struct in6_addr *addr);
  47
  48/* Big ac list lock for all the sockets */
  49static DEFINE_RWLOCK(ipv6_sk_ac_lock);
  50
  51
  52/*
  53 *      socket join an anycast group
  54 */
  55
  56int ipv6_sock_ac_join(struct sock *sk, int ifindex, struct in6_addr *addr)
  57{
  58        struct ipv6_pinfo *np = inet6_sk(sk);
  59        struct net_device *dev = NULL;
  60        struct inet6_dev *idev;
  61        struct ipv6_ac_socklist *pac;
  62        struct net *net = sock_net(sk);
  63        int     ishost = !net->ipv6.devconf_all->forwarding;
  64        int     err = 0;
  65
  66        if (!capable(CAP_NET_ADMIN))
  67                return -EPERM;
  68        if (ipv6_addr_is_multicast(addr))
  69                return -EINVAL;
  70        if (ipv6_chk_addr(net, addr, NULL, 0))
  71                return -EINVAL;
  72
  73        pac = sock_kmalloc(sk, sizeof(struct ipv6_ac_socklist), GFP_KERNEL);
  74        if (pac == NULL)
  75                return -ENOMEM;
  76        pac->acl_next = NULL;
  77        ipv6_addr_copy(&pac->acl_addr, addr);
  78
  79        if (ifindex == 0) {
  80                struct rt6_info *rt;
  81
  82                rt = rt6_lookup(net, addr, NULL, 0, 0);
  83                if (rt) {
  84                        dev = rt->rt6i_dev;
  85                        dev_hold(dev);
  86                        dst_release(&rt->u.dst);
  87                } else if (ishost) {
  88                        err = -EADDRNOTAVAIL;
  89                        goto out_free_pac;
  90                } else {
  91                        /* router, no matching interface: just pick one */
  92
  93                        dev = dev_get_by_flags(net, IFF_UP, IFF_UP|IFF_LOOPBACK);
  94                }
  95        } else
  96                dev = dev_get_by_index(net, ifindex);
  97
  98        if (dev == NULL) {
  99                err = -ENODEV;
 100                goto out_free_pac;
 101        }
 102
 103        idev = in6_dev_get(dev);
 104        if (!idev) {
 105                if (ifindex)
 106                        err = -ENODEV;
 107                else
 108                        err = -EADDRNOTAVAIL;
 109                goto out_dev_put;
 110        }
 111        /* reset ishost, now that we have a specific device */
 112        ishost = !idev->cnf.forwarding;
 113        in6_dev_put(idev);
 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 out_dev_put;
 127        }
 128
 129        err = ipv6_dev_ac_inc(dev, addr);
 130        if (err)
 131                goto out_dev_put;
 132
 133        write_lock_bh(&ipv6_sk_ac_lock);
 134        pac->acl_next = np->ipv6_ac_list;
 135        np->ipv6_ac_list = pac;
 136        write_unlock_bh(&ipv6_sk_ac_lock);
 137
 138        dev_put(dev);
 139
 140        return 0;
 141
 142out_dev_put:
 143        dev_put(dev);
 144out_free_pac:
 145        sock_kfree_s(sk, pac, sizeof(*pac));
 146        return err;
 147}
 148
 149/*
 150 *      socket leave an anycast group
 151 */
 152int ipv6_sock_ac_drop(struct sock *sk, int ifindex, struct in6_addr *addr)
 153{
 154        struct ipv6_pinfo *np = inet6_sk(sk);
 155        struct net_device *dev;
 156        struct ipv6_ac_socklist *pac, *prev_pac;
 157        struct net *net = sock_net(sk);
 158
 159        write_lock_bh(&ipv6_sk_ac_lock);
 160        prev_pac = NULL;
 161        for (pac = np->ipv6_ac_list; pac; pac = pac->acl_next) {
 162                if ((ifindex == 0 || pac->acl_ifindex == ifindex) &&
 163                     ipv6_addr_equal(&pac->acl_addr, addr))
 164                        break;
 165                prev_pac = pac;
 166        }
 167        if (!pac) {
 168                write_unlock_bh(&ipv6_sk_ac_lock);
 169                return -ENOENT;
 170        }
 171        if (prev_pac)
 172                prev_pac->acl_next = pac->acl_next;
 173        else
 174                np->ipv6_ac_list = pac->acl_next;
 175
 176        write_unlock_bh(&ipv6_sk_ac_lock);
 177
 178        dev = dev_get_by_index(net, pac->acl_ifindex);
 179        if (dev) {
 180                ipv6_dev_ac_dec(dev, &pac->acl_addr);
 181                dev_put(dev);
 182        }
 183        sock_kfree_s(sk, pac, sizeof(*pac));
 184        return 0;
 185}
 186
 187void ipv6_sock_ac_close(struct sock *sk)
 188{
 189        struct ipv6_pinfo *np = inet6_sk(sk);
 190        struct net_device *dev = NULL;
 191        struct ipv6_ac_socklist *pac;
 192        struct net *net = sock_net(sk);
 193        int     prev_index;
 194
 195        write_lock_bh(&ipv6_sk_ac_lock);
 196        pac = np->ipv6_ac_list;
 197        np->ipv6_ac_list = NULL;
 198        write_unlock_bh(&ipv6_sk_ac_lock);
 199
 200        prev_index = 0;
 201        while (pac) {
 202                struct ipv6_ac_socklist *next = pac->acl_next;
 203
 204                if (pac->acl_ifindex != prev_index) {
 205                        if (dev)
 206                                dev_put(dev);
 207                        dev = dev_get_by_index(net, pac->acl_ifindex);
 208                        prev_index = pac->acl_ifindex;
 209                }
 210                if (dev)
 211                        ipv6_dev_ac_dec(dev, &pac->acl_addr);
 212                sock_kfree_s(sk, pac, sizeof(*pac));
 213                pac = next;
 214        }
 215        if (dev)
 216                dev_put(dev);
 217}
 218
 219#if 0
 220/* The function is not used, which is funny. Apparently, author
 221 * supposed to use it to filter out datagrams inside udp/raw but forgot.
 222 *
 223 * It is OK, anycasts are not special comparing to delivery to unicasts.
 224 */
 225
 226int inet6_ac_check(struct sock *sk, struct in6_addr *addr, int ifindex)
 227{
 228        struct ipv6_ac_socklist *pac;
 229        struct ipv6_pinfo *np = inet6_sk(sk);
 230        int     found;
 231
 232        found = 0;
 233        read_lock(&ipv6_sk_ac_lock);
 234        for (pac=np->ipv6_ac_list; pac; pac=pac->acl_next) {
 235                if (ifindex && pac->acl_ifindex != ifindex)
 236                        continue;
 237                found = ipv6_addr_equal(&pac->acl_addr, addr);
 238                if (found)
 239                        break;
 240        }
 241        read_unlock(&ipv6_sk_ac_lock);
 242
 243        return found;
 244}
 245
 246#endif
 247
 248static void aca_put(struct ifacaddr6 *ac)
 249{
 250        if (atomic_dec_and_test(&ac->aca_refcnt)) {
 251                in6_dev_put(ac->aca_idev);
 252                dst_release(&ac->aca_rt->u.dst);
 253                kfree(ac);
 254        }
 255}
 256
 257/*
 258 *      device anycast group inc (add if not found)
 259 */
 260int ipv6_dev_ac_inc(struct net_device *dev, struct in6_addr *addr)
 261{
 262        struct ifacaddr6 *aca;
 263        struct inet6_dev *idev;
 264        struct rt6_info *rt;
 265        int err;
 266
 267        idev = in6_dev_get(dev);
 268
 269        if (idev == NULL)
 270                return -EINVAL;
 271
 272        write_lock_bh(&idev->lock);
 273        if (idev->dead) {
 274                err = -ENODEV;
 275                goto out;
 276        }
 277
 278        for (aca = idev->ac_list; aca; aca = aca->aca_next) {
 279                if (ipv6_addr_equal(&aca->aca_addr, addr)) {
 280                        aca->aca_users++;
 281                        err = 0;
 282                        goto out;
 283                }
 284        }
 285
 286        /*
 287         *      not found: create a new one.
 288         */
 289
 290        aca = kzalloc(sizeof(struct ifacaddr6), GFP_ATOMIC);
 291
 292        if (aca == NULL) {
 293                err = -ENOMEM;
 294                goto out;
 295        }
 296
 297        rt = addrconf_dst_alloc(idev, addr, 1);
 298        if (IS_ERR(rt)) {
 299                kfree(aca);
 300                err = PTR_ERR(rt);
 301                goto out;
 302        }
 303
 304        ipv6_addr_copy(&aca->aca_addr, addr);
 305        aca->aca_idev = idev;
 306        aca->aca_rt = rt;
 307        aca->aca_users = 1;
 308        /* aca_tstamp should be updated upon changes */
 309        aca->aca_cstamp = aca->aca_tstamp = jiffies;
 310        atomic_set(&aca->aca_refcnt, 2);
 311        spin_lock_init(&aca->aca_lock);
 312
 313        aca->aca_next = idev->ac_list;
 314        idev->ac_list = aca;
 315        write_unlock_bh(&idev->lock);
 316
 317        ip6_ins_rt(rt);
 318
 319        addrconf_join_solict(dev, &aca->aca_addr);
 320
 321        aca_put(aca);
 322        return 0;
 323out:
 324        write_unlock_bh(&idev->lock);
 325        in6_dev_put(idev);
 326        return err;
 327}
 328
 329/*
 330 *      device anycast group decrement
 331 */
 332int __ipv6_dev_ac_dec(struct inet6_dev *idev, struct in6_addr *addr)
 333{
 334        struct ifacaddr6 *aca, *prev_aca;
 335
 336        write_lock_bh(&idev->lock);
 337        prev_aca = NULL;
 338        for (aca = idev->ac_list; aca; aca = aca->aca_next) {
 339                if (ipv6_addr_equal(&aca->aca_addr, addr))
 340                        break;
 341                prev_aca = aca;
 342        }
 343        if (!aca) {
 344                write_unlock_bh(&idev->lock);
 345                return -ENOENT;
 346        }
 347        if (--aca->aca_users > 0) {
 348                write_unlock_bh(&idev->lock);
 349                return 0;
 350        }
 351        if (prev_aca)
 352                prev_aca->aca_next = aca->aca_next;
 353        else
 354                idev->ac_list = aca->aca_next;
 355        write_unlock_bh(&idev->lock);
 356        addrconf_leave_solict(idev, &aca->aca_addr);
 357
 358        dst_hold(&aca->aca_rt->u.dst);
 359        ip6_del_rt(aca->aca_rt);
 360
 361        aca_put(aca);
 362        return 0;
 363}
 364
 365static int ipv6_dev_ac_dec(struct net_device *dev, struct in6_addr *addr)
 366{
 367        int ret;
 368        struct inet6_dev *idev = in6_dev_get(dev);
 369        if (idev == NULL)
 370                return -ENODEV;
 371        ret = __ipv6_dev_ac_dec(idev, addr);
 372        in6_dev_put(idev);
 373        return ret;
 374}
 375
 376/*
 377 *      check if the interface has this anycast address
 378 */
 379static int ipv6_chk_acast_dev(struct net_device *dev, struct in6_addr *addr)
 380{
 381        struct inet6_dev *idev;
 382        struct ifacaddr6 *aca;
 383
 384        idev = in6_dev_get(dev);
 385        if (idev) {
 386                read_lock_bh(&idev->lock);
 387                for (aca = idev->ac_list; aca; aca = aca->aca_next)
 388                        if (ipv6_addr_equal(&aca->aca_addr, addr))
 389                                break;
 390                read_unlock_bh(&idev->lock);
 391                in6_dev_put(idev);
 392                return aca != NULL;
 393        }
 394        return 0;
 395}
 396
 397/*
 398 *      check if given interface (or any, if dev==0) has this anycast address
 399 */
 400int ipv6_chk_acast_addr(struct net *net, struct net_device *dev,
 401                        struct in6_addr *addr)
 402{
 403        int found = 0;
 404
 405        if (dev)
 406                return ipv6_chk_acast_dev(dev, addr);
 407        read_lock(&dev_base_lock);
 408        for_each_netdev(net, dev)
 409                if (ipv6_chk_acast_dev(dev, addr)) {
 410                        found = 1;
 411                        break;
 412                }
 413        read_unlock(&dev_base_lock);
 414        return found;
 415}
 416
 417
 418#ifdef CONFIG_PROC_FS
 419struct ac6_iter_state {
 420        struct seq_net_private p;
 421        struct net_device *dev;
 422        struct inet6_dev *idev;
 423};
 424
 425#define ac6_seq_private(seq)    ((struct ac6_iter_state *)(seq)->private)
 426
 427static inline struct ifacaddr6 *ac6_get_first(struct seq_file *seq)
 428{
 429        struct ifacaddr6 *im = NULL;
 430        struct ac6_iter_state *state = ac6_seq_private(seq);
 431        struct net *net = seq_file_net(seq);
 432
 433        state->idev = NULL;
 434        for_each_netdev(net, state->dev) {
 435                struct inet6_dev *idev;
 436                idev = in6_dev_get(state->dev);
 437                if (!idev)
 438                        continue;
 439                read_lock_bh(&idev->lock);
 440                im = idev->ac_list;
 441                if (im) {
 442                        state->idev = idev;
 443                        break;
 444                }
 445                read_unlock_bh(&idev->lock);
 446                in6_dev_put(idev);
 447        }
 448        return im;
 449}
 450
 451static struct ifacaddr6 *ac6_get_next(struct seq_file *seq, struct ifacaddr6 *im)
 452{
 453        struct ac6_iter_state *state = ac6_seq_private(seq);
 454
 455        im = im->aca_next;
 456        while (!im) {
 457                if (likely(state->idev != NULL)) {
 458                        read_unlock_bh(&state->idev->lock);
 459                        in6_dev_put(state->idev);
 460                }
 461                state->dev = next_net_device(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
 475static 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
 484static void *ac6_seq_start(struct seq_file *seq, loff_t *pos)
 485        __acquires(dev_base_lock)
 486{
 487        read_lock(&dev_base_lock);
 488        return ac6_get_idx(seq, *pos);
 489}
 490
 491static void *ac6_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 492{
 493        struct ifacaddr6 *im;
 494        im = ac6_get_next(seq, v);
 495        ++*pos;
 496        return im;
 497}
 498
 499static void ac6_seq_stop(struct seq_file *seq, void *v)
 500        __releases(dev_base_lock)
 501{
 502        struct ac6_iter_state *state = ac6_seq_private(seq);
 503        if (likely(state->idev != NULL)) {
 504                read_unlock_bh(&state->idev->lock);
 505                in6_dev_put(state->idev);
 506        }
 507        read_unlock(&dev_base_lock);
 508}
 509
 510static int ac6_seq_show(struct seq_file *seq, void *v)
 511{
 512        struct ifacaddr6 *im = (struct ifacaddr6 *)v;
 513        struct ac6_iter_state *state = ac6_seq_private(seq);
 514
 515        seq_printf(seq, "%-4d %-15s %pi6 %5d\n",
 516                   state->dev->ifindex, state->dev->name,
 517                   &im->aca_addr, im->aca_users);
 518        return 0;
 519}
 520
 521static const struct seq_operations ac6_seq_ops = {
 522        .start  =       ac6_seq_start,
 523        .next   =       ac6_seq_next,
 524        .stop   =       ac6_seq_stop,
 525        .show   =       ac6_seq_show,
 526};
 527
 528static int ac6_seq_open(struct inode *inode, struct file *file)
 529{
 530        return seq_open_net(inode, file, &ac6_seq_ops,
 531                            sizeof(struct ac6_iter_state));
 532}
 533
 534static const struct file_operations ac6_seq_fops = {
 535        .owner          =       THIS_MODULE,
 536        .open           =       ac6_seq_open,
 537        .read           =       seq_read,
 538        .llseek         =       seq_lseek,
 539        .release        =       seq_release_net,
 540};
 541
 542int ac6_proc_init(struct net *net)
 543{
 544        if (!proc_net_fops_create(net, "anycast6", S_IRUGO, &ac6_seq_fops))
 545                return -ENOMEM;
 546
 547        return 0;
 548}
 549
 550void ac6_proc_exit(struct net *net)
 551{
 552        proc_net_remove(net, "anycast6");
 553}
 554#endif
 555
 556