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 {
  33 #ifdef CONFIG_NET_NS
  34         struct net *lbl_net;
  35 #endif
  36         struct in6_addr prefix;
  37         int prefixlen;
  38         int ifindex;
  39         int addrtype;
  40         u32 label;
  41         struct hlist_node list;
  42         atomic_t refcnt;
  43         struct rcu_head rcu;
  44 };
  45
  46 static struct ip6addrlbl_table
  47 {
  48         struct hlist_head head;
  49         spinlock_t lock;
  50         u32 seq;
  51 } ip6addrlbl_table;
  52
  53 static inline
  54 struct net *ip6addrlbl_net(const struct ip6addrlbl_entry *lbl)
  55 {
  56         return read_pnet(&lbl->lbl_net);
  57 }
  58
  59 /*
  60  * Default policy table (RFC3484 + extensions)
  61  *
  62  * prefix               addr_type       label
  63  * -------------------------------------------------------------------------
  64  * ::1/128              LOOPBACK        0
  65  * ::/0                 N/A             1
  66  * 2002::/16            N/A             2
  67  * ::/96                COMPATv4        3
  68  * ::ffff:0:0/96        V4MAPPED        4
  69  * fc00::/7             N/A             5               ULA (RFC 4193)
  70  * 2001::/32            N/A             6               Teredo (RFC 4380)
  71  * 2001:10::/28         N/A             7               ORCHID (RFC 4843)
  72  *
  73  * Note: 0xffffffff is used if we do not have any policies.
  74  */
  75
  76 #define IPV6_ADDR_LABEL_DEFAULT 0xffffffffUL
  77
  78 static const __net_initdata struct ip6addrlbl_init_table
  79 {
  80         const struct in6_addr *prefix;
  81         int prefixlen;
  82         u32 label;
  83 } ip6addrlbl_init_table[] = {
  84         {       /* ::/0 */
  85                 .prefix = &in6addr_any,
  86                 .label = 1,
  87         },{     /* fc00::/7 */
  88                 .prefix = &(struct in6_addr){{{ 0xfc }}},
  89                 .prefixlen = 7,
  90                 .label = 5,
  91         },{     /* 2002::/16 */
  92                 .prefix = &(struct in6_addr){{{ 0x20, 0x02 }}},
  93                 .prefixlen = 16,
  94                 .label = 2,
  95         },{     /* 2001::/32 */
  96                 .prefix = &(struct in6_addr){{{ 0x20, 0x01 }}},
  97                 .prefixlen = 32,
  98                 .label = 6,
  99         },{     /* 2001:10::/28 */
 100                 .prefix = &(struct in6_addr){{{ 0x20, 0x01, 0x00, 0x10 }}},
 101                 .prefixlen = 28,
 102                 .label = 7,
 103         },{     /* ::ffff:0:0 */
 104                 .prefix = &(struct in6_addr){{{ [10] = 0xff, [11] = 0xff }}},
 105                 .prefixlen = 96,
 106                 .label = 4,
 107         },{     /* ::/96 */
 108                 .prefix = &in6addr_any,
 109                 .prefixlen = 96,
 110                 .label = 3,
 111         },{     /* ::1/128 */
 112                 .prefix = &in6addr_loopback,
 113                 .prefixlen = 128,
 114                 .label = 0,
 115         }
 116 };
 117
 118 /* Object management */
 119 static inline void ip6addrlbl_free(struct ip6addrlbl_entry *p)
 120 {
 121 #ifdef CONFIG_NET_NS
 122         release_net(p->lbl_net);
 123 #endif
 124         kfree(p);
 125 }
 126
 127 static void ip6addrlbl_free_rcu(struct rcu_head *h)
 128 {
 129         ip6addrlbl_free(container_of(h, struct ip6addrlbl_entry, rcu));
 130 }
 131
 132 static bool ip6addrlbl_hold(struct ip6addrlbl_entry *p)
 133 {
 134         return atomic_inc_not_zero(&p->refcnt);
 135 }
 136
 137 static inline void ip6addrlbl_put(struct ip6addrlbl_entry *p)
 138 {
 139         if (atomic_dec_and_test(&p->refcnt))
 140                 call_rcu(&p->rcu, ip6addrlbl_free_rcu);
 141 }
 142
 143 /* Find label */
 144 static bool __ip6addrlbl_match(struct net *net,
 145                                const struct ip6addrlbl_entry *p,
 146                                const struct in6_addr *addr,
 147                                int addrtype, int ifindex)
 148 {
 149         if (!net_eq(ip6addrlbl_net(p), net))
 150                 return false;
 151         if (p->ifindex && p->ifindex != ifindex)
 152                 return false;
 153         if (p->addrtype && p->addrtype != addrtype)
 154                 return false;
 155         if (!ipv6_prefix_equal(addr, &p->prefix, p->prefixlen))
 156                 return false;
 157         return true;
 158 }
 159
 160 static struct ip6addrlbl_entry *__ipv6_addr_label(struct net *net,
 161                                                   const struct in6_addr *addr,
 162                                                   int type, int ifindex)
 163 {
 164         struct hlist_node *pos;
 165         struct ip6addrlbl_entry *p;
 166         hlist_for_each_entry_rcu(p, pos, &ip6addrlbl_table.head, list) {
 167                 if (__ip6addrlbl_match(net, p, addr, type, ifindex))
 168                         return p;
 169         }
 170         return NULL;
 171 }
 172
 173 u32 ipv6_addr_label(struct net *net,
 174                     const struct in6_addr *addr, int type, int ifindex)
 175 {
 176         u32 label;
 177         struct ip6addrlbl_entry *p;
 178
 179         type &= IPV6_ADDR_MAPPED | IPV6_ADDR_COMPATv4 | IPV6_ADDR_LOOPBACK;
 180
 181         rcu_read_lock();
 182         p = __ipv6_addr_label(net, addr, type, ifindex);
 183         label = p ? p->label : IPV6_ADDR_LABEL_DEFAULT;
 184         rcu_read_unlock();
 185
 186         ADDRLABEL(KERN_DEBUG "%s(addr=%pI6, type=%d, ifindex=%d) => %08x\n",
 187                   __func__, addr, type, ifindex, label);
 188
 189         return label;
 190 }
 191
 192 /* allocate one entry */
 193 static struct ip6addrlbl_entry *ip6addrlbl_alloc(struct net *net,
 194                                                  const struct in6_addr *prefix,
 195                                                  int prefixlen, int ifindex,
 196                                                  u32 label)
 197 {
 198         struct ip6addrlbl_entry *newp;
 199         int addrtype;
 200
 201         ADDRLABEL(KERN_DEBUG "%s(prefix=%pI6, prefixlen=%d, ifindex=%d, label=%u)\n",
 202                   __func__, prefix, prefixlen, ifindex, (unsigned int)label);
 203
 204         addrtype = ipv6_addr_type(prefix) & (IPV6_ADDR_MAPPED | IPV6_ADDR_COMPATv4 | IPV6_ADDR_LOOPBACK);
 205
 206         switch (addrtype) {
 207         case IPV6_ADDR_MAPPED:
 208                 if (prefixlen > 96)
 209                         return ERR_PTR(-EINVAL);
 210                 if (prefixlen < 96)
 211                         addrtype = 0;
 212                 break;
 213         case IPV6_ADDR_COMPATv4:
 214                 if (prefixlen != 96)
 215                         addrtype = 0;
 216                 break;
 217         case IPV6_ADDR_LOOPBACK:
 218                 if (prefixlen != 128)
 219                         addrtype = 0;
 220                 break;
 221         }
 222
 223         newp = kmalloc(sizeof(*newp), GFP_KERNEL);
 224         if (!newp)
 225                 return ERR_PTR(-ENOMEM);
 226
 227         ipv6_addr_prefix(&newp->prefix, prefix, prefixlen);
 228         newp->prefixlen = prefixlen;
 229         newp->ifindex = ifindex;
 230         newp->addrtype = addrtype;
 231         newp->label = label;
 232         INIT_HLIST_NODE(&newp->list);
 233 #ifdef CONFIG_NET_NS
 234         newp->lbl_net = hold_net(net);
 235 #endif
 236         atomic_set(&newp->refcnt, 1);
 237         return newp;
 238 }
 239
 240 /* add a label */
 241 static int __ip6addrlbl_add(struct ip6addrlbl_entry *newp, int replace)
 242 {
 243         int ret = 0;
 244
 245         ADDRLABEL(KERN_DEBUG "%s(newp=%p, replace=%d)\n",
 246                         __func__,
 247                         newp, replace);
 248
 249         if (hlist_empty(&ip6addrlbl_table.head)) {
 250                 hlist_add_head_rcu(&newp->list, &ip6addrlbl_table.head);
 251         } else {
 252                 struct hlist_node *pos, *n;
 253                 struct ip6addrlbl_entry *p = NULL;
 254                 hlist_for_each_entry_safe(p, pos, n,
 255                                           &ip6addrlbl_table.head, list) {
 256                         if (p->prefixlen == newp->prefixlen &&
 257                             net_eq(ip6addrlbl_net(p), ip6addrlbl_net(newp)) &&
 258                             p->ifindex == newp->ifindex &&
 259                             ipv6_addr_equal(&p->prefix, &newp->prefix)) {
 260                                 if (!replace) {
 261                                         ret = -EEXIST;
 262                                         goto out;
 263                                 }
 264                                 hlist_replace_rcu(&p->list, &newp->list);
 265                                 ip6addrlbl_put(p);
 266                                 goto out;
 267                         } else if ((p->prefixlen == newp->prefixlen && !p->ifindex) ||
 268                                    (p->prefixlen < newp->prefixlen)) {
 269                                 hlist_add_before_rcu(&newp->list, &p->list);
 270                                 goto out;
 271                         }
 272                 }
 273                 hlist_add_after_rcu(&p->list, &newp->list);
 274         }
 275 out:
 276         if (!ret)
 277                 ip6addrlbl_table.seq++;
 278         return ret;
 279 }
 280
 281 /* add a label */
 282 static int ip6addrlbl_add(struct net *net,
 283                           const struct in6_addr *prefix, int prefixlen,
 284                           int ifindex, u32 label, int replace)
 285 {
 286         struct ip6addrlbl_entry *newp;
 287         int ret = 0;
 288
 289         ADDRLABEL(KERN_DEBUG "%s(prefix=%pI6, prefixlen=%d, ifindex=%d, label=%u, replace=%d)\n",
 290                   __func__, prefix, prefixlen, ifindex, (unsigned int)label,
 291                   replace);
 292
 293         newp = ip6addrlbl_alloc(net, prefix, prefixlen, ifindex, label);
 294         if (IS_ERR(newp))
 295                 return PTR_ERR(newp);
 296         spin_lock(&ip6addrlbl_table.lock);
 297         ret = __ip6addrlbl_add(newp, replace);
 298         spin_unlock(&ip6addrlbl_table.lock);
 299         if (ret)
 300                 ip6addrlbl_free(newp);
 301         return ret;
 302 }
 303
 304 /* remove a label */
 305 static int __ip6addrlbl_del(struct net *net,
 306                             const struct in6_addr *prefix, int prefixlen,
 307                             int ifindex)
 308 {
 309         struct ip6addrlbl_entry *p = NULL;
 310         struct hlist_node *pos, *n;
 311         int ret = -ESRCH;
 312
 313         ADDRLABEL(KERN_DEBUG "%s(prefix=%pI6, prefixlen=%d, ifindex=%d)\n",
 314                   __func__, prefix, prefixlen, ifindex);
 315
 316         hlist_for_each_entry_safe(p, pos, n, &ip6addrlbl_table.head, list) {
 317                 if (p->prefixlen == prefixlen &&
 318                     net_eq(ip6addrlbl_net(p), net) &&
 319                     p->ifindex == ifindex &&
 320                     ipv6_addr_equal(&p->prefix, prefix)) {
 321                         hlist_del_rcu(&p->list);
 322                         ip6addrlbl_put(p);
 323                         ret = 0;
 324                         break;
 325                 }
 326         }
 327         return ret;
 328 }
 329
 330 static int ip6addrlbl_del(struct net *net,
 331                           const struct in6_addr *prefix, int prefixlen,
 332                           int ifindex)
 333 {
 334         struct in6_addr prefix_buf;
 335         int ret;
 336
 337         ADDRLABEL(KERN_DEBUG "%s(prefix=%pI6, prefixlen=%d, ifindex=%d)\n",
 338                   __func__, prefix, prefixlen, ifindex);
 339
 340         ipv6_addr_prefix(&prefix_buf, prefix, prefixlen);
 341         spin_lock(&ip6addrlbl_table.lock);
 342         ret = __ip6addrlbl_del(net, &prefix_buf, prefixlen, ifindex);
 343         spin_unlock(&ip6addrlbl_table.lock);
 344         return ret;
 345 }
 346
 347 /* add default label */
 348 static int __net_init ip6addrlbl_net_init(struct net *net)
 349 {
 350         int err = 0;
 351         int i;
 352
 353         ADDRLABEL(KERN_DEBUG "%s\n", __func__);
 354
 355         for (i = 0; i < ARRAY_SIZE(ip6addrlbl_init_table); i++) {
 356                 int ret = ip6addrlbl_add(net,
 357                                          ip6addrlbl_init_table[i].prefix,
 358                                          ip6addrlbl_init_table[i].prefixlen,
 359                                          0,
 360                                          ip6addrlbl_init_table[i].label, 0);
 361                 /* XXX: should we free all rules when we catch an error? */
 362                 if (ret && (!err || err != -ENOMEM))
 363                         err = ret;
 364         }
 365         return err;
 366 }
 367
 368 static void __net_exit ip6addrlbl_net_exit(struct net *net)
 369 {
 370         struct ip6addrlbl_entry *p = NULL;
 371         struct hlist_node *pos, *n;
 372
 373         /* Remove all labels belonging to the exiting net */
 374         spin_lock(&ip6addrlbl_table.lock);
 375         hlist_for_each_entry_safe(p, pos, n, &ip6addrlbl_table.head, list) {
 376                 if (net_eq(ip6addrlbl_net(p), net)) {
 377                         hlist_del_rcu(&p->list);
 378                         ip6addrlbl_put(p);
 379                 }
 380         }
 381         spin_unlock(&ip6addrlbl_table.lock);
 382 }
 383
 384 static struct pernet_operations ipv6_addr_label_ops = {
 385         .init = ip6addrlbl_net_init,
 386         .exit = ip6addrlbl_net_exit,
 387 };
 388
 389 int __init ipv6_addr_label_init(void)
 390 {
 391         spin_lock_init(&ip6addrlbl_table.lock);
 392
 393         return register_pernet_subsys(&ipv6_addr_label_ops);
 394 }
 395
 396 void ipv6_addr_label_cleanup(void)
 397 {
 398         unregister_pernet_subsys(&ipv6_addr_label_ops);
 399 }
 400
 401 static const struct nla_policy ifal_policy[IFAL_MAX+1] = {
 402         [IFAL_ADDRESS]          = { .len = sizeof(struct in6_addr), },
 403         [IFAL_LABEL]            = { .len = sizeof(u32), },
 404 };
 405
 406 static int ip6addrlbl_newdel(struct sk_buff *skb, struct nlmsghdr *nlh,
 407                              void *arg)
 408 {
 409         struct net *net = sock_net(skb->sk);
 410         struct ifaddrlblmsg *ifal;
 411         struct nlattr *tb[IFAL_MAX+1];
 412         struct in6_addr *pfx;
 413         u32 label;
 414         int err = 0;
 415
 416         err = nlmsg_parse(nlh, sizeof(*ifal), tb, IFAL_MAX, ifal_policy);
 417         if (err < 0)
 418                 return err;
 419
 420         ifal = nlmsg_data(nlh);
 421
 422         if (ifal->ifal_family != AF_INET6 ||
 423             ifal->ifal_prefixlen > 128)
 424                 return -EINVAL;
 425
 426         if (!tb[IFAL_ADDRESS])
 427                 return -EINVAL;
 428
 429         pfx = nla_data(tb[IFAL_ADDRESS]);
 430         if (!pfx)
 431                 return -EINVAL;
 432
 433         if (!tb[IFAL_LABEL])
 434                 return -EINVAL;
 435         label = nla_get_u32(tb[IFAL_LABEL]);
 436         if (label == IPV6_ADDR_LABEL_DEFAULT)
 437                 return -EINVAL;
 438
 439         switch(nlh->nlmsg_type) {
 440         case RTM_NEWADDRLABEL:
 441                 if (ifal->ifal_index &&
 442                     !__dev_get_by_index(net, ifal->ifal_index))
 443                         return -EINVAL;
 444
 445                 err = ip6addrlbl_add(net, pfx, ifal->ifal_prefixlen,
 446                                      ifal->ifal_index, label,
 447                                      nlh->nlmsg_flags & NLM_F_REPLACE);
 448                 break;
 449         case RTM_DELADDRLABEL:
 450                 err = ip6addrlbl_del(net, pfx, ifal->ifal_prefixlen,
 451                                      ifal->ifal_index);
 452                 break;
 453         default:
 454                 err = -EOPNOTSUPP;
 455         }
 456         return err;
 457 }
 458
 459 static void ip6addrlbl_putmsg(struct nlmsghdr *nlh,
 460                               int prefixlen, int ifindex, u32 lseq)
 461 {
 462         struct ifaddrlblmsg *ifal = nlmsg_data(nlh);
 463         ifal->ifal_family = AF_INET6;
 464         ifal->ifal_prefixlen = prefixlen;
 465         ifal->ifal_flags = 0;
 466         ifal->ifal_index = ifindex;
 467         ifal->ifal_seq = lseq;
 468 };
 469
 470 static int ip6addrlbl_fill(struct sk_buff *skb,
 471                            struct ip6addrlbl_entry *p,
 472                            u32 lseq,
 473                            u32 pid, u32 seq, int event,
 474                            unsigned int flags)
 475 {
 476         struct nlmsghdr *nlh = nlmsg_put(skb, pid, seq, event,
 477                                          sizeof(struct ifaddrlblmsg), flags);
 478         if (!nlh)
 479                 return -EMSGSIZE;
 480
 481         ip6addrlbl_putmsg(nlh, p->prefixlen, p->ifindex, lseq);
 482
 483         if (nla_put(skb, IFAL_ADDRESS, 16, &p->prefix) < 0 ||
 484             nla_put_u32(skb, IFAL_LABEL, p->label) < 0) {
 485                 nlmsg_cancel(skb, nlh);
 486                 return -EMSGSIZE;
 487         }
 488
 489         return nlmsg_end(skb, nlh);
 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         struct hlist_node *pos;
 497         int idx = 0, s_idx = cb->args[0];
 498         int err;
 499
 500         rcu_read_lock();
 501         hlist_for_each_entry_rcu(p, pos, &ip6addrlbl_table.head, list) {
 502                 if (idx >= s_idx &&
 503                     net_eq(ip6addrlbl_net(p), net)) {
 504                         if ((err = ip6addrlbl_fill(skb, p,
 505                                                    ip6addrlbl_table.seq,
 506                                                    NETLINK_CB(cb->skb).pid,
 507                                                    cb->nlh->nlmsg_seq,
 508                                                    RTM_NEWADDRLABEL,
 509                                                    NLM_F_MULTI)) <= 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                           void *arg)
 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         if (err < 0)
 540                 return err;
 541
 542         ifal = nlmsg_data(nlh);
 543
 544         if (ifal->ifal_family != AF_INET6 ||
 545             ifal->ifal_prefixlen != 128)
 546                 return -EINVAL;
 547
 548         if (ifal->ifal_index &&
 549             !__dev_get_by_index(net, ifal->ifal_index))
 550                 return -EINVAL;
 551
 552         if (!tb[IFAL_ADDRESS])
 553                 return -EINVAL;
 554
 555         addr = nla_data(tb[IFAL_ADDRESS]);
 556         if (!addr)
 557                 return -EINVAL;
 558
 559         rcu_read_lock();
 560         p = __ipv6_addr_label(net, addr, ipv6_addr_type(addr), ifal->ifal_index);
 561         if (p && ip6addrlbl_hold(p))
 562                 p = NULL;
 563         lseq = ip6addrlbl_table.seq;
 564         rcu_read_unlock();
 565
 566         if (!p) {
 567                 err = -ESRCH;
 568                 goto out;
 569         }
 570
 571         if (!(skb = nlmsg_new(ip6addrlbl_msgsize(), GFP_KERNEL))) {
 572                 ip6addrlbl_put(p);
 573                 return -ENOBUFS;
 574         }
 575
 576         err = ip6addrlbl_fill(skb, p, lseq,
 577                               NETLINK_CB(in_skb).pid, nlh->nlmsg_seq,
 578                               RTM_NEWADDRLABEL, 0);
 579
 580         ip6addrlbl_put(p);
 581
 582         if (err < 0) {
 583                 WARN_ON(err == -EMSGSIZE);
 584                 kfree_skb(skb);
 585                 goto out;
 586         }
 587
 588         err = rtnl_unicast(skb, net, NETLINK_CB(in_skb).pid);
 589 out:
 590         return err;
 591 }
 592
 593 void __init ipv6_addr_label_rtnl_register(void)
 594 {
 595         __rtnl_register(PF_INET6, RTM_NEWADDRLABEL, ip6addrlbl_newdel,
 596                         NULL, NULL);
 597         __rtnl_register(PF_INET6, RTM_DELADDRLABEL, ip6addrlbl_newdel,
 598                         NULL, NULL);
 599         __rtnl_register(PF_INET6, RTM_GETADDRLABEL, ip6addrlbl_get,
 600                         ip6addrlbl_dump, NULL);
 601 }
 602