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, const 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, 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
 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, 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
 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
 214static 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 */
 226int 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;
 289out:
 290        write_unlock_bh(&idev->lock);
 291        in6_dev_put(idev);
 292        return err;
 293}
 294
 295/*
 296 *      device anycast group decrement
 297 */
 298int __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() */
 332static 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 */
 345static 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 */
 365bool 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
 385struct 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
 393static 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
 416static 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
 439static 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
 448static 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
 455static 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
 463static 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
 475static 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
 486static 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
 493static 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
 499static 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
 507int __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
 515void ac6_proc_exit(struct net *net)
 516{
 517        proc_net_remove(net, "anycast6");
 518}
 519#endif
 520
 521
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