net/ipv6/addrlabel.c

   1 /*
   2  * IPv6 Address Label subsystem
   3  * for the IPv6 "Default" Source Address Selection
   4  *
   5  * Copyright (C)2007 USAGI/WIDE Project
   6  */
   7 /*
   8  * Author:
   9  *      YOSHIFUJI Hideaki @ USAGI/WIDE Project <yoshfuji@linux-ipv6.org>
  10  */
  11
  12 #include <linux/kernel.h>
  13 #include <linux/list.h>
  14 #include <linux/rcupdate.h>
  15 #include <linux/in6.h>
  16 #include <linux/slab.h>
  17 #include <net/addrconf.h>
  18 #include <linux/if_addrlabel.h>
  19 #include <linux/netlink.h>
  20 #include <linux/rtnetlink.h>
  21
  22 #if 0
  23 #define ADDRLABEL(x...) printk(x)
  24 #else
  25 #define ADDRLABEL(x...) do { ; } while (0)
  26 #endif
  27
  28 /*
  29  * Policy Table
  30  */
  31 struct ip6addrlbl_entry {
  32         possible_net_t lbl_net;
  33         struct in6_addr prefix;
  34         int prefixlen;
  35         int ifindex;
  36         int addrtype;
  37         u32 label;
  38         struct hlist_node list;
  39         atomic_t refcnt;
  40         struct rcu_head rcu;
  41 };
  42
  43 static struct ip6addrlbl_table
  44 {
  45         struct hlist_head head;
  46         spinlock_t lock;
  47         u32 seq;
  48 } ip6addrlbl_table;
  49
  50 static inline
  51 struct net *ip6addrlbl_net(const struct ip6addrlbl_entry *lbl)
  52 {
  53         return read_pnet(&lbl->lbl_net);
  54 }
  55
  56 /*
  57  * Default policy table (RFC6724 + extensions)
  58  *
  59  * prefix               addr_type       label
  60  * -------------------------------------------------------------------------
  61  * ::1/128              LOOPBACK        0
  62  * ::/0                 N/A             1
  63  * 2002::/16            N/A             2
  64  * ::/96                COMPATv4        3
  65  * ::ffff:0:0/96        V4MAPPED        4
  66  * fc00::/7             N/A             5               ULA (RFC 4193)
  67  * 2001::/32            N/A             6               Teredo (RFC 4380)
  68  * 2001:10::/28         N/A             7               ORCHID (RFC 4843)
  69  * fec0::/10            N/A             11              Site-local
  70  *                                                      (deprecated by RFC3879)
  71  * 3ffe::/16            N/A             12              6bone
  72  *
  73  * Note: 0xffffffff is used if we do not have any policies.
  74  * Note: Labels for ULA and 6to4 are different from labels listed in RFC6724.
  75  */
  76
  77 #define IPV6_ADDR_LABEL_DEFAULT 0xffffffffUL
  78
  79 static const __net_initconst struct ip6addrlbl_init_table
  80 {
  81         const struct in6_addr *prefix;
  82         int prefixlen;
  83         u32 label;
  84 } ip6addrlbl_init_table[] = {
  85         {       /* ::/0 */
  86                 .prefix = &in6addr_any,
  87                 .label = 1,
  88         }, {    /* fc00::/7 */
  89                 .prefix = &(struct in6_addr){ { { 0xfc } } } ,
  90                 .prefixlen = 7,
  91                 .label = 5,
  92         }, {    /* fec0::/10 */
  93                 .prefix = &(struct in6_addr){ { { 0xfe, 0xc0 } } },
  94                 .prefixlen = 10,
  95                 .label = 11,
  96         }, {    /* 2002::/16 */
  97                 .prefix = &(struct in6_addr){ { { 0x20, 0x02 } } },
  98                 .prefixlen = 16,
  99                 .label = 2,
 100         }, {    /* 3ffe::/16 */
 101                 .prefix = &(struct in6_addr){ { { 0x3f, 0xfe } } },
 102                 .prefixlen = 16,
 103                 .label = 12,
 104         }, {    /* 2001::/32 */
 105                 .prefix = &(struct in6_addr){ { { 0x20, 0x01 } } },
 106                 .prefixlen = 32,
 107                 .label = 6,
 108         }, {    /* 2001:10::/28 */
 109                 .prefix = &(struct in6_addr){ { { 0x20, 0x01, 0x00, 0x10 } } },
 110                 .prefixlen = 28,
 111                 .label = 7,
 112         }, {    /* ::ffff:0:0 */
 113                 .prefix = &(struct in6_addr){ { { [10] = 0xff, [11] = 0xff } } },
 114                 .prefixlen = 96,
 115                 .label = 4,
 116         }, {    /* ::/96 */
 117                 .prefix = &in6addr_any,
 118                 .prefixlen = 96,
 119                 .label = 3,
 120         }, {    /* ::1/128 */
 121                 .prefix = &in6addr_loopback,
 122                 .prefixlen = 128,
 123                 .label = 0,
 124         }
 125 };
 126
 127 /* Object management */
 128 static inline void ip6addrlbl_free(struct ip6addrlbl_entry *p)
 129 {
 130         kfree(p);
 131 }
 132
 133 static void ip6addrlbl_free_rcu(struct rcu_head *h)
 134 {
 135         ip6addrlbl_free(container_of(h, struct ip6addrlbl_entry, rcu));
 136 }
 137
 138 static bool ip6addrlbl_hold(struct ip6addrlbl_entry *p)
 139 {
 140         return atomic_inc_not_zero(&p->refcnt);
 141 }
 142
 143 static inline void ip6addrlbl_put(struct ip6addrlbl_entry *p)
 144 {
 145         if (atomic_dec_and_test(&p->refcnt))
 146                 call_rcu(&p->rcu, ip6addrlbl_free_rcu);
 147 }
 148
 149 /* Find label */
 150 static bool __ip6addrlbl_match(struct net *net,
 151                                const struct ip6addrlbl_entry *p,
 152                                const struct in6_addr *addr,
 153                                int addrtype, int ifindex)
 154 {
 155         if (!net_eq(ip6addrlbl_net(p), net))
 156                 return false;
 157         if (p->ifindex && p->ifindex != ifindex)
 158                 return false;
 159         if (p->addrtype && p->addrtype != addrtype)
 160                 return false;
 161         if (!ipv6_prefix_equal(addr, &p->prefix, p->prefixlen))
 162                 return false;
 163         return true;
 164 }
 165
 166 static struct ip6addrlbl_entry *__ipv6_addr_label(struct net *net,
 167                                                   const struct in6_addr *addr,
 168                                                   int type, int ifindex)
 169 {
 170         struct ip6addrlbl_entry *p;
 171         hlist_for_each_entry_rcu(p, &ip6addrlbl_table.head, list) {
 172                 if (__ip6addrlbl_match(net, p, addr, type, ifindex))
 173                         return p;
 174         }
 175         return NULL;
 176 }
 177
 178 u32 ipv6_addr_label(struct net *net,
 179                     const struct in6_addr *addr, int type, int ifindex)
 180 {
 181         u32 label;
 182         struct ip6addrlbl_entry *p;
 183
 184         type &= IPV6_ADDR_MAPPED | IPV6_ADDR_COMPATv4 | IPV6_ADDR_LOOPBACK;
 185
 186         rcu_read_lock();
 187         p = __ipv6_addr_label(net, addr, type, ifindex);
 188         label = p ? p->label : IPV6_ADDR_LABEL_DEFAULT;
 189         rcu_read_unlock();
 190
 191         ADDRLABEL(KERN_DEBUG "%s(addr=%pI6, type=%d, ifindex=%d) => %08x\n",
 192                   __func__, addr, type, ifindex, label);
 193
 194         return label;
 195 }
 196
 197 /* allocate one entry */
 198 static struct ip6addrlbl_entry *ip6addrlbl_alloc(struct net *net,
 199                                                  const struct in6_addr *prefix,
 200                                                  int prefixlen, int ifindex,
 201                                                  u32 label)
 202 {
 203         struct ip6addrlbl_entry *newp;
 204         int addrtype;
 205
 206         ADDRLABEL(KERN_DEBUG "%s(prefix=%pI6, prefixlen=%d, ifindex=%d, label=%u)\n",
 207                   __func__, prefix, prefixlen, ifindex, (unsigned int)label);
 208
 209         addrtype = ipv6_addr_type(prefix) & (IPV6_ADDR_MAPPED | IPV6_ADDR_COMPATv4 | IPV6_ADDR_LOOPBACK);
 210
 211         switch (addrtype) {
 212         case IPV6_ADDR_MAPPED:
 213                 if (prefixlen > 96)
 214                         return ERR_PTR(-EINVAL);
 215                 if (prefixlen < 96)
 216                         addrtype = 0;
 217                 break;
 218         case IPV6_ADDR_COMPATv4:
 219                 if (prefixlen != 96)
 220                         addrtype = 0;
 221                 break;
 222         case IPV6_ADDR_LOOPBACK:
 223                 if (prefixlen != 128)
 224                         addrtype = 0;
 225                 break;
 226         }
 227
 228         newp = kmalloc(sizeof(*newp), GFP_KERNEL);
 229         if (!newp)
 230                 return ERR_PTR(-ENOMEM);
 231
 232         ipv6_addr_prefix(&newp->prefix, prefix, prefixlen);
 233         newp->prefixlen = prefixlen;
 234         newp->ifindex = ifindex;
 235         newp->addrtype = addrtype;
 236         newp->label = label;
 237         INIT_HLIST_NODE(&newp->list);
 238         write_pnet(&newp->lbl_net, net);
 239         atomic_set(&newp->refcnt, 1);
 240         return newp;
 241 }
 242
 243 /* add a label */
 244 static int __ip6addrlbl_add(struct ip6addrlbl_entry *newp, int replace)
 245 {
 246         struct hlist_node *n;
 247         struct ip6addrlbl_entry *last = NULL, *p = NULL;
 248         int ret = 0;
 249
 250         ADDRLABEL(KERN_DEBUG "%s(newp=%p, replace=%d)\n", __func__, newp,
 251                   replace);
 252
 253         hlist_for_each_entry_safe(p, n, &ip6addrlbl_table.head, list) {
 254                 if (p->prefixlen == newp->prefixlen &&
 255                     net_eq(ip6addrlbl_net(p), ip6addrlbl_net(newp)) &&
 256                     p->ifindex == newp->ifindex &&
 257                     ipv6_addr_equal(&p->prefix, &newp->prefix)) {
 258                         if (!replace) {
 259                                 ret = -EEXIST;
 260                                 goto out;
 261                         }
 262                         hlist_replace_rcu(&p->list, &newp->list);
 263                         ip6addrlbl_put(p);
 264                         goto out;
 265                 } else if ((p->prefixlen == newp->prefixlen && !p->ifindex) ||
 266                            (p->prefixlen < newp->prefixlen)) {
 267                         hlist_add_before_rcu(&newp->list, &p->list);
 268                         goto out;
 269                 }
 270                 last = p;
 271         }
 272         if (last)
 273                 hlist_add_behind_rcu(&newp->list, &last->list);
 274         else
 275                 hlist_add_head_rcu(&newp->list, &ip6addrlbl_table.head);
 276 out:
 277         if (!ret)
 278                 ip6addrlbl_table.seq++;
 279         return ret;
 280 }
 281
 282 /* add a label */
 283 static int ip6addrlbl_add(struct net *net,
 284                           const struct in6_addr *prefix, int prefixlen,
 285                           int ifindex, u32 label, int replace)
 286 {
 287         struct ip6addrlbl_entry *newp;
 288         int ret = 0;
 289
 290         ADDRLABEL(KERN_DEBUG "%s(prefix=%pI6, prefixlen=%d, ifindex=%d, label=%u, replace=%d)\n",
 291                   __func__, prefix, prefixlen, ifindex, (unsigned int)label,
 292                   replace);
 293
 294         newp = ip6addrlbl_alloc(net, prefix, prefixlen, ifindex, label);
 295         if (IS_ERR(newp))
 296                 return PTR_ERR(newp);
 297         spin_lock(&ip6addrlbl_table.lock);
 298         ret = __ip6addrlbl_add(newp, replace);
 299         spin_unlock(&ip6addrlbl_table.lock);
 300         if (ret)
 301                 ip6addrlbl_free(newp);
 302         return ret;
 303 }
 304
 305 /* remove a label */
 306 static int __ip6addrlbl_del(struct net *net,
 307                             const struct in6_addr *prefix, int prefixlen,
 308                             int ifindex)
 309 {
 310         struct ip6addrlbl_entry *p = NULL;
 311         struct hlist_node *n;
 312         int ret = -ESRCH;
 313
 314         ADDRLABEL(KERN_DEBUG "%s(prefix=%pI6, prefixlen=%d, ifindex=%d)\n",
 315                   __func__, prefix, prefixlen, ifindex);
 316
 317         hlist_for_each_entry_safe(p, n, &ip6addrlbl_table.head, list) {
 318                 if (p->prefixlen == prefixlen &&
 319                     net_eq(ip6addrlbl_net(p), net) &&
 320                     p->ifindex == ifindex &&
 321                     ipv6_addr_equal(&p->prefix, prefix)) {
 322                         hlist_del_rcu(&p->list);
 323                         ip6addrlbl_put(p);
 324                         ret = 0;
 325                         break;
 326                 }
 327         }
 328         return ret;
 329 }
 330
 331 static int ip6addrlbl_del(struct net *net,
 332                           const struct in6_addr *prefix, int prefixlen,
 333                           int ifindex)
 334 {
 335         struct in6_addr prefix_buf;
 336         int ret;
 337
 338         ADDRLABEL(KERN_DEBUG "%s(prefix=%pI6, prefixlen=%d, ifindex=%d)\n",
 339                   __func__, prefix, prefixlen, ifindex);
 340
 341         ipv6_addr_prefix(&prefix_buf, prefix, prefixlen);
 342         spin_lock(&ip6addrlbl_table.lock);
 343         ret = __ip6addrlbl_del(net, &prefix_buf, prefixlen, ifindex);
 344         spin_unlock(&ip6addrlbl_table.lock);
 345         return ret;
 346 }
 347
 348 /* add default label */
 349 static int __net_init ip6addrlbl_net_init(struct net *net)
 350 {
 351         int err = 0;
 352         int i;
 353
 354         ADDRLABEL(KERN_DEBUG "%s\n", __func__);
 355
 356         for (i = 0; i < ARRAY_SIZE(ip6addrlbl_init_table); i++) {
 357                 int ret = ip6addrlbl_add(net,
 358                                          ip6addrlbl_init_table[i].prefix,
 359                                          ip6addrlbl_init_table[i].prefixlen,
 360                                          0,
 361                                          ip6addrlbl_init_table[i].label, 0);
 362                 /* XXX: should we free all rules when we catch an error? */
 363                 if (ret && (!err || err != -ENOMEM))
 364                         err = ret;
 365         }
 366         return err;
 367 }
 368
 369 static void __net_exit ip6addrlbl_net_exit(struct net *net)
 370 {
 371         struct ip6addrlbl_entry *p = NULL;
 372         struct hlist_node *n;
 373
 374         /* Remove all labels belonging to the exiting net */
 375         spin_lock(&ip6addrlbl_table.lock);
 376         hlist_for_each_entry_safe(p, n, &ip6addrlbl_table.head, list) {
 377                 if (net_eq(ip6addrlbl_net(p), net)) {
 378                         hlist_del_rcu(&p->list);
 379                         ip6addrlbl_put(p);
 380                 }
 381         }
 382         spin_unlock(&ip6addrlbl_table.lock);
 383 }
 384
 385 static struct pernet_operations ipv6_addr_label_ops = {
 386         .init = ip6addrlbl_net_init,
 387         .exit = ip6addrlbl_net_exit,
 388 };
 389
 390 int __init ipv6_addr_label_init(void)
 391 {
 392         spin_lock_init(&ip6addrlbl_table.lock);
 393
 394         return register_pernet_subsys(&ipv6_addr_label_ops);
 395 }
 396
 397 void ipv6_addr_label_cleanup(void)
 398 {
 399         unregister_pernet_subsys(&ipv6_addr_label_ops);
 400 }
 401
 402 static const struct nla_policy ifal_policy[IFAL_MAX+1] = {
 403         [IFAL_ADDRESS]          = { .len = sizeof(struct in6_addr), },
 404         [IFAL_LABEL]            = { .len = sizeof(u32), },
 405 };
 406
 407 static int ip6addrlbl_newdel(struct sk_buff *skb, struct nlmsghdr *nlh,
 408                              struct netlink_ext_ack *extack)
 409 {
 410         struct net *net = sock_net(skb->sk);
 411         struct ifaddrlblmsg *ifal;
 412         struct nlattr *tb[IFAL_MAX+1];
 413         struct in6_addr *pfx;
 414         u32 label;
 415         int err = 0;
 416
 417         err = nlmsg_parse(nlh, sizeof(*ifal), tb, IFAL_MAX, ifal_policy,
 418                           extack);
 419         if (err < 0)
 420                 return err;
 421
 422         ifal = nlmsg_data(nlh);
 423
 424         if (ifal->ifal_family != AF_INET6 ||
 425             ifal->ifal_prefixlen > 128)
 426                 return -EINVAL;
 427
 428         if (!tb[IFAL_ADDRESS])
 429                 return -EINVAL;
 430         pfx = nla_data(tb[IFAL_ADDRESS]);
 431
 432         if (!tb[IFAL_LABEL])
 433                 return -EINVAL;
 434         label = nla_get_u32(tb[IFAL_LABEL]);
 435         if (label == IPV6_ADDR_LABEL_DEFAULT)
 436                 return -EINVAL;
 437
 438         switch (nlh->nlmsg_type) {
 439         case RTM_NEWADDRLABEL:
 440                 if (ifal->ifal_index &&
 441                     !__dev_get_by_index(net, ifal->ifal_index))
 442                         return -EINVAL;
 443
 444                 err = ip6addrlbl_add(net, pfx, ifal->ifal_prefixlen,
 445                                      ifal->ifal_index, label,
 446                                      nlh->nlmsg_flags & NLM_F_REPLACE);
 447                 break;
 448         case RTM_DELADDRLABEL:
 449                 err = ip6addrlbl_del(net, pfx, ifal->ifal_prefixlen,
 450                                      ifal->ifal_index);
 451                 break;
 452         default:
 453                 err = -EOPNOTSUPP;
 454         }
 455         return err;
 456 }
 457
 458 static void ip6addrlbl_putmsg(struct nlmsghdr *nlh,
 459                               int prefixlen, int ifindex, u32 lseq)
 460 {
 461         struct ifaddrlblmsg *ifal = nlmsg_data(nlh);
 462         ifal->ifal_family = AF_INET6;
 463         ifal->ifal_prefixlen = prefixlen;
 464         ifal->ifal_flags = 0;
 465         ifal->ifal_index = ifindex;
 466         ifal->ifal_seq = lseq;
 467 };
 468
 469 static int ip6addrlbl_fill(struct sk_buff *skb,
 470                            struct ip6addrlbl_entry *p,
 471                            u32 lseq,
 472                            u32 portid, u32 seq, int event,
 473                            unsigned int flags)
 474 {
 475         struct nlmsghdr *nlh = nlmsg_put(skb, portid, seq, event,
 476                                          sizeof(struct ifaddrlblmsg), flags);
 477         if (!nlh)
 478                 return -EMSGSIZE;
 479
 480         ip6addrlbl_putmsg(nlh, p->prefixlen, p->ifindex, lseq);
 481
 482         if (nla_put_in6_addr(skb, IFAL_ADDRESS, &p->prefix) < 0 ||
 483             nla_put_u32(skb, IFAL_LABEL, p->label) < 0) {
 484                 nlmsg_cancel(skb, nlh);
 485                 return -EMSGSIZE;
 486         }
 487
 488         nlmsg_end(skb, nlh);
 489         return 0;
 490 }
 491
 492 static int ip6addrlbl_dump(struct sk_buff *skb, struct netlink_callback *cb)
 493 {
 494         struct net *net = sock_net(skb->sk);
 495         struct ip6addrlbl_entry *p;
 496         int idx = 0, s_idx = cb->args[0];
 497         int err;
 498
 499         rcu_read_lock();
 500         hlist_for_each_entry_rcu(p, &ip6addrlbl_table.head, list) {
 501                 if (idx >= s_idx &&
 502                     net_eq(ip6addrlbl_net(p), net)) {
 503                         err = ip6addrlbl_fill(skb, p,
 504                                               ip6addrlbl_table.seq,
 505                                               NETLINK_CB(cb->skb).portid,
 506                                               cb->nlh->nlmsg_seq,
 507                                               RTM_NEWADDRLABEL,
 508                                               NLM_F_MULTI);
 509                         if (err < 0)
 510                                 break;
 511                 }
 512                 idx++;
 513         }
 514         rcu_read_unlock();
 515         cb->args[0] = idx;
 516         return skb->len;
 517 }
 518
 519 static inline int ip6addrlbl_msgsize(void)
 520 {
 521         return NLMSG_ALIGN(sizeof(struct ifaddrlblmsg))
 522                 + nla_total_size(16)    /* IFAL_ADDRESS */
 523                 + nla_total_size(4);    /* IFAL_LABEL */
 524 }
 525
 526 static int ip6addrlbl_get(struct sk_buff *in_skb, struct nlmsghdr *nlh,
 527                           struct netlink_ext_ack *extack)
 528 {
 529         struct net *net = sock_net(in_skb->sk);
 530         struct ifaddrlblmsg *ifal;
 531         struct nlattr *tb[IFAL_MAX+1];
 532         struct in6_addr *addr;
 533         u32 lseq;
 534         int err = 0;
 535         struct ip6addrlbl_entry *p;
 536         struct sk_buff *skb;
 537
 538         err = nlmsg_parse(nlh, sizeof(*ifal), tb, IFAL_MAX, ifal_policy,
 539                           extack);
 540         if (err < 0)
 541                 return err;
 542
 543         ifal = nlmsg_data(nlh);
 544
 545         if (ifal->ifal_family != AF_INET6 ||
 546             ifal->ifal_prefixlen != 128)
 547                 return -EINVAL;
 548
 549         if (ifal->ifal_index &&
 550             !__dev_get_by_index(net, ifal->ifal_index))
 551                 return -EINVAL;
 552
 553         if (!tb[IFAL_ADDRESS])
 554                 return -EINVAL;
 555         addr = nla_data(tb[IFAL_ADDRESS]);
 556
 557         rcu_read_lock();
 558         p = __ipv6_addr_label(net, addr, ipv6_addr_type(addr), ifal->ifal_index);
 559         if (p && !ip6addrlbl_hold(p))
 560                 p = NULL;
 561         lseq = ip6addrlbl_table.seq;
 562         rcu_read_unlock();
 563
 564         if (!p) {
 565                 err = -ESRCH;
 566                 goto out;
 567         }
 568
 569         skb = nlmsg_new(ip6addrlbl_msgsize(), GFP_KERNEL);
 570         if (!skb) {
 571                 ip6addrlbl_put(p);
 572                 return -ENOBUFS;
 573         }
 574
 575         err = ip6addrlbl_fill(skb, p, lseq,
 576                               NETLINK_CB(in_skb).portid, nlh->nlmsg_seq,
 577                               RTM_NEWADDRLABEL, 0);
 578
 579         ip6addrlbl_put(p);
 580
 581         if (err < 0) {
 582                 WARN_ON(err == -EMSGSIZE);
 583                 kfree_skb(skb);
 584                 goto out;
 585         }
 586
 587         err = rtnl_unicast(skb, net, NETLINK_CB(in_skb).portid);
 588 out:
 589         return err;
 590 }
 591
 592 void __init ipv6_addr_label_rtnl_register(void)
 593 {
 594         __rtnl_register(PF_INET6, RTM_NEWADDRLABEL, ip6addrlbl_newdel,
 595                         NULL, NULL);
 596         __rtnl_register(PF_INET6, RTM_DELADDRLABEL, ip6addrlbl_newdel,
 597                         NULL, NULL);
 598         __rtnl_register(PF_INET6, RTM_GETADDRLABEL, ip6addrlbl_get,
 599                         ip6addrlbl_dump, NULL);
 600 }
 601