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 (RFC6724 + 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  * fec0::/10            N/A             11              Site-local
  73  *                                                      (deprecated by RFC3879)
  74  * 3ffe::/16            N/A             12              6bone
  75  *
  76  * Note: 0xffffffff is used if we do not have any policies.
  77  * Note: Labels for ULA and 6to4 are different from labels listed in RFC6724.
  78  */
  79
  80 #define IPV6_ADDR_LABEL_DEFAULT 0xffffffffUL
  81
  82 static const __net_initconst struct ip6addrlbl_init_table
  83 {
  84         const struct in6_addr *prefix;
  85         int prefixlen;
  86         u32 label;
  87 } ip6addrlbl_init_table[] = {
  88         {       /* ::/0 */
  89                 .prefix = &in6addr_any,
  90                 .label = 1,
  91         },{     /* fc00::/7 */
  92                 .prefix = &(struct in6_addr){{{ 0xfc }}},
  93                 .prefixlen = 7,
  94                 .label = 5,
  95         },{     /* fec0::/10 */
  96                 .prefix = &(struct in6_addr){{{ 0xfe, 0xc0 }}},
  97                 .prefixlen = 10,
  98                 .label = 11,
  99         },{     /* 2002::/16 */
 100                 .prefix = &(struct in6_addr){{{ 0x20, 0x02 }}},
 101                 .prefixlen = 16,
 102                 .label = 2,
 103         },{     /* 3ffe::/16 */
 104                 .prefix = &(struct in6_addr){{{ 0x3f, 0xfe }}},
 105                 .prefixlen = 16,
 106                 .label = 12,
 107         },{     /* 2001::/32 */
 108                 .prefix = &(struct in6_addr){{{ 0x20, 0x01 }}},
 109                 .prefixlen = 32,
 110                 .label = 6,
 111         },{     /* 2001:10::/28 */
 112                 .prefix = &(struct in6_addr){{{ 0x20, 0x01, 0x00, 0x10 }}},
 113                 .prefixlen = 28,
 114                 .label = 7,
 115         },{     /* ::ffff:0:0 */
 116                 .prefix = &(struct in6_addr){{{ [10] = 0xff, [11] = 0xff }}},
 117                 .prefixlen = 96,
 118                 .label = 4,
 119         },{     /* ::/96 */
 120                 .prefix = &in6addr_any,
 121                 .prefixlen = 96,
 122                 .label = 3,
 123         },{     /* ::1/128 */
 124                 .prefix = &in6addr_loopback,
 125                 .prefixlen = 128,
 126                 .label = 0,
 127         }
 128 };
 129
 130 /* Object management */
 131 static inline void ip6addrlbl_free(struct ip6addrlbl_entry *p)
 132 {
 133 #ifdef CONFIG_NET_NS
 134         release_net(p->lbl_net);
 135 #endif
 136         kfree(p);
 137 }
 138
 139 static void ip6addrlbl_free_rcu(struct rcu_head *h)
 140 {
 141         ip6addrlbl_free(container_of(h, struct ip6addrlbl_entry, rcu));
 142 }
 143
 144 static bool ip6addrlbl_hold(struct ip6addrlbl_entry *p)
 145 {
 146         return atomic_inc_not_zero(&p->refcnt);
 147 }
 148
 149 static inline void ip6addrlbl_put(struct ip6addrlbl_entry *p)
 150 {
 151         if (atomic_dec_and_test(&p->refcnt))
 152                 call_rcu(&p->rcu, ip6addrlbl_free_rcu);
 153 }
 154
 155 /* Find label */
 156 static bool __ip6addrlbl_match(struct net *net,
 157                                const struct ip6addrlbl_entry *p,
 158                                const struct in6_addr *addr,
 159                                int addrtype, int ifindex)
 160 {
 161         if (!net_eq(ip6addrlbl_net(p), net))
 162                 return false;
 163         if (p->ifindex && p->ifindex != ifindex)
 164                 return false;
 165         if (p->addrtype && p->addrtype != addrtype)
 166                 return false;
 167         if (!ipv6_prefix_equal(addr, &p->prefix, p->prefixlen))
 168                 return false;
 169         return true;
 170 }
 171
 172 static struct ip6addrlbl_entry *__ipv6_addr_label(struct net *net,
 173                                                   const struct in6_addr *addr,
 174                                                   int type, int ifindex)
 175 {
 176         struct ip6addrlbl_entry *p;
 177         hlist_for_each_entry_rcu(p, &ip6addrlbl_table.head, list) {
 178                 if (__ip6addrlbl_match(net, p, addr, type, ifindex))
 179                         return p;
 180         }
 181         return NULL;
 182 }
 183
 184 u32 ipv6_addr_label(struct net *net,
 185                     const struct in6_addr *addr, int type, int ifindex)
 186 {
 187         u32 label;
 188         struct ip6addrlbl_entry *p;
 189
 190         type &= IPV6_ADDR_MAPPED | IPV6_ADDR_COMPATv4 | IPV6_ADDR_LOOPBACK;
 191
 192         rcu_read_lock();
 193         p = __ipv6_addr_label(net, addr, type, ifindex);
 194         label = p ? p->label : IPV6_ADDR_LABEL_DEFAULT;
 195         rcu_read_unlock();
 196
 197         ADDRLABEL(KERN_DEBUG "%s(addr=%pI6, type=%d, ifindex=%d) => %08x\n",
 198                   __func__, addr, type, ifindex, label);
 199
 200         return label;
 201 }
 202
 203 /* allocate one entry */
 204 static struct ip6addrlbl_entry *ip6addrlbl_alloc(struct net *net,
 205                                                  const struct in6_addr *prefix,
 206                                                  int prefixlen, int ifindex,
 207                                                  u32 label)
 208 {
 209         struct ip6addrlbl_entry *newp;
 210         int addrtype;
 211
 212         ADDRLABEL(KERN_DEBUG "%s(prefix=%pI6, prefixlen=%d, ifindex=%d, label=%u)\n",
 213                   __func__, prefix, prefixlen, ifindex, (unsigned int)label);
 214
 215         addrtype = ipv6_addr_type(prefix) & (IPV6_ADDR_MAPPED | IPV6_ADDR_COMPATv4 | IPV6_ADDR_LOOPBACK);
 216
 217         switch (addrtype) {
 218         case IPV6_ADDR_MAPPED:
 219                 if (prefixlen > 96)
 220                         return ERR_PTR(-EINVAL);
 221                 if (prefixlen < 96)
 222                         addrtype = 0;
 223                 break;
 224         case IPV6_ADDR_COMPATv4:
 225                 if (prefixlen != 96)
 226                         addrtype = 0;
 227                 break;
 228         case IPV6_ADDR_LOOPBACK:
 229                 if (prefixlen != 128)
 230                         addrtype = 0;
 231                 break;
 232         }
 233
 234         newp = kmalloc(sizeof(*newp), GFP_KERNEL);
 235         if (!newp)
 236                 return ERR_PTR(-ENOMEM);
 237
 238         ipv6_addr_prefix(&newp->prefix, prefix, prefixlen);
 239         newp->prefixlen = prefixlen;
 240         newp->ifindex = ifindex;
 241         newp->addrtype = addrtype;
 242         newp->label = label;
 243         INIT_HLIST_NODE(&newp->list);
 244 #ifdef CONFIG_NET_NS
 245         newp->lbl_net = hold_net(net);
 246 #endif
 247         atomic_set(&newp->refcnt, 1);
 248         return newp;
 249 }
 250
 251 /* add a label */
 252 static int __ip6addrlbl_add(struct ip6addrlbl_entry *newp, int replace)
 253 {
 254         int ret = 0;
 255
 256         ADDRLABEL(KERN_DEBUG "%s(newp=%p, replace=%d)\n",
 257                         __func__,
 258                         newp, replace);
 259
 260         if (hlist_empty(&ip6addrlbl_table.head)) {
 261                 hlist_add_head_rcu(&newp->list, &ip6addrlbl_table.head);
 262         } else {
 263                 struct hlist_node *n;
 264                 struct ip6addrlbl_entry *p = NULL;
 265                 hlist_for_each_entry_safe(p, n,
 266                                           &ip6addrlbl_table.head, list) {
 267                         if (p->prefixlen == newp->prefixlen &&
 268                             net_eq(ip6addrlbl_net(p), ip6addrlbl_net(newp)) &&
 269                             p->ifindex == newp->ifindex &&
 270                             ipv6_addr_equal(&p->prefix, &newp->prefix)) {
 271                                 if (!replace) {
 272                                         ret = -EEXIST;
 273                                         goto out;
 274                                 }
 275                                 hlist_replace_rcu(&p->list, &newp->list);
 276                                 ip6addrlbl_put(p);
 277                                 goto out;
 278                         } else if ((p->prefixlen == newp->prefixlen && !p->ifindex) ||
 279                                    (p->prefixlen < newp->prefixlen)) {
 280                                 hlist_add_before_rcu(&newp->list, &p->list);
 281                                 goto out;
 282                         }
 283                 }
 284                 hlist_add_after_rcu(&p->list, &newp->list);
 285         }
 286 out:
 287         if (!ret)
 288                 ip6addrlbl_table.seq++;
 289         return ret;
 290 }
 291
 292 /* add a label */
 293 static int ip6addrlbl_add(struct net *net,
 294                           const struct in6_addr *prefix, int prefixlen,
 295                           int ifindex, u32 label, int replace)
 296 {
 297         struct ip6addrlbl_entry *newp;
 298         int ret = 0;
 299
 300         ADDRLABEL(KERN_DEBUG "%s(prefix=%pI6, prefixlen=%d, ifindex=%d, label=%u, replace=%d)\n",
 301                   __func__, prefix, prefixlen, ifindex, (unsigned int)label,
 302                   replace);
 303
 304         newp = ip6addrlbl_alloc(net, prefix, prefixlen, ifindex, label);
 305         if (IS_ERR(newp))
 306                 return PTR_ERR(newp);
 307         spin_lock(&ip6addrlbl_table.lock);
 308         ret = __ip6addrlbl_add(newp, replace);
 309         spin_unlock(&ip6addrlbl_table.lock);
 310         if (ret)
 311                 ip6addrlbl_free(newp);
 312         return ret;
 313 }
 314
 315 /* remove a label */
 316 static int __ip6addrlbl_del(struct net *net,
 317                             const struct in6_addr *prefix, int prefixlen,
 318                             int ifindex)
 319 {
 320         struct ip6addrlbl_entry *p = NULL;
 321         struct hlist_node *n;
 322         int ret = -ESRCH;
 323
 324         ADDRLABEL(KERN_DEBUG "%s(prefix=%pI6, prefixlen=%d, ifindex=%d)\n",
 325                   __func__, prefix, prefixlen, ifindex);
 326
 327         hlist_for_each_entry_safe(p, n, &ip6addrlbl_table.head, list) {
 328                 if (p->prefixlen == prefixlen &&
 329                     net_eq(ip6addrlbl_net(p), net) &&
 330                     p->ifindex == ifindex &&
 331                     ipv6_addr_equal(&p->prefix, prefix)) {
 332                         hlist_del_rcu(&p->list);
 333                         ip6addrlbl_put(p);
 334                         ret = 0;
 335                         break;
 336                 }
 337         }
 338         return ret;
 339 }
 340
 341 static int ip6addrlbl_del(struct net *net,
 342                           const struct in6_addr *prefix, int prefixlen,
 343                           int ifindex)
 344 {
 345         struct in6_addr prefix_buf;
 346         int ret;
 347
 348         ADDRLABEL(KERN_DEBUG "%s(prefix=%pI6, prefixlen=%d, ifindex=%d)\n",
 349                   __func__, prefix, prefixlen, ifindex);
 350
 351         ipv6_addr_prefix(&prefix_buf, prefix, prefixlen);
 352         spin_lock(&ip6addrlbl_table.lock);
 353         ret = __ip6addrlbl_del(net, &prefix_buf, prefixlen, ifindex);
 354         spin_unlock(&ip6addrlbl_table.lock);
 355         return ret;
 356 }
 357
 358 /* add default label */
 359 static int __net_init ip6addrlbl_net_init(struct net *net)
 360 {
 361         int err = 0;
 362         int i;
 363
 364         ADDRLABEL(KERN_DEBUG "%s\n", __func__);
 365
 366         for (i = 0; i < ARRAY_SIZE(ip6addrlbl_init_table); i++) {
 367                 int ret = ip6addrlbl_add(net,
 368                                          ip6addrlbl_init_table[i].prefix,
 369                                          ip6addrlbl_init_table[i].prefixlen,
 370                                          0,
 371                                          ip6addrlbl_init_table[i].label, 0);
 372                 /* XXX: should we free all rules when we catch an error? */
 373                 if (ret && (!err || err != -ENOMEM))
 374                         err = ret;
 375         }
 376         return err;
 377 }
 378
 379 static void __net_exit ip6addrlbl_net_exit(struct net *net)
 380 {
 381         struct ip6addrlbl_entry *p = NULL;
 382         struct hlist_node *n;
 383
 384         /* Remove all labels belonging to the exiting net */
 385         spin_lock(&ip6addrlbl_table.lock);
 386         hlist_for_each_entry_safe(p, n, &ip6addrlbl_table.head, list) {
 387                 if (net_eq(ip6addrlbl_net(p), net)) {
 388                         hlist_del_rcu(&p->list);
 389                         ip6addrlbl_put(p);
 390                 }
 391         }
 392         spin_unlock(&ip6addrlbl_table.lock);
 393 }
 394
 395 static struct pernet_operations ipv6_addr_label_ops = {
 396         .init = ip6addrlbl_net_init,
 397         .exit = ip6addrlbl_net_exit,
 398 };
 399
 400 int __init ipv6_addr_label_init(void)
 401 {
 402         spin_lock_init(&ip6addrlbl_table.lock);
 403
 404         return register_pernet_subsys(&ipv6_addr_label_ops);
 405 }
 406
 407 void ipv6_addr_label_cleanup(void)
 408 {
 409         unregister_pernet_subsys(&ipv6_addr_label_ops);
 410 }
 411
 412 static const struct nla_policy ifal_policy[IFAL_MAX+1] = {
 413         [IFAL_ADDRESS]          = { .len = sizeof(struct in6_addr), },
 414         [IFAL_LABEL]            = { .len = sizeof(u32), },
 415 };
 416
 417 static int ip6addrlbl_newdel(struct sk_buff *skb, struct nlmsghdr *nlh,
 418                              void *arg)
 419 {
 420         struct net *net = sock_net(skb->sk);
 421         struct ifaddrlblmsg *ifal;
 422         struct nlattr *tb[IFAL_MAX+1];
 423         struct in6_addr *pfx;
 424         u32 label;
 425         int err = 0;
 426
 427         err = nlmsg_parse(nlh, sizeof(*ifal), tb, IFAL_MAX, ifal_policy);
 428         if (err < 0)
 429                 return err;
 430
 431         ifal = nlmsg_data(nlh);
 432
 433         if (ifal->ifal_family != AF_INET6 ||
 434             ifal->ifal_prefixlen > 128)
 435                 return -EINVAL;
 436
 437         if (!tb[IFAL_ADDRESS])
 438                 return -EINVAL;
 439
 440         pfx = nla_data(tb[IFAL_ADDRESS]);
 441         if (!pfx)
 442                 return -EINVAL;
 443
 444         if (!tb[IFAL_LABEL])
 445                 return -EINVAL;
 446         label = nla_get_u32(tb[IFAL_LABEL]);
 447         if (label == IPV6_ADDR_LABEL_DEFAULT)
 448                 return -EINVAL;
 449
 450         switch(nlh->nlmsg_type) {
 451         case RTM_NEWADDRLABEL:
 452                 if (ifal->ifal_index &&
 453                     !__dev_get_by_index(net, ifal->ifal_index))
 454                         return -EINVAL;
 455
 456                 err = ip6addrlbl_add(net, pfx, ifal->ifal_prefixlen,
 457                                      ifal->ifal_index, label,
 458                                      nlh->nlmsg_flags & NLM_F_REPLACE);
 459                 break;
 460         case RTM_DELADDRLABEL:
 461                 err = ip6addrlbl_del(net, pfx, ifal->ifal_prefixlen,
 462                                      ifal->ifal_index);
 463                 break;
 464         default:
 465                 err = -EOPNOTSUPP;
 466         }
 467         return err;
 468 }
 469
 470 static void ip6addrlbl_putmsg(struct nlmsghdr *nlh,
 471                               int prefixlen, int ifindex, u32 lseq)
 472 {
 473         struct ifaddrlblmsg *ifal = nlmsg_data(nlh);
 474         ifal->ifal_family = AF_INET6;
 475         ifal->ifal_prefixlen = prefixlen;
 476         ifal->ifal_flags = 0;
 477         ifal->ifal_index = ifindex;
 478         ifal->ifal_seq = lseq;
 479 };
 480
 481 static int ip6addrlbl_fill(struct sk_buff *skb,
 482                            struct ip6addrlbl_entry *p,
 483                            u32 lseq,
 484                            u32 portid, u32 seq, int event,
 485                            unsigned int flags)
 486 {
 487         struct nlmsghdr *nlh = nlmsg_put(skb, portid, seq, event,
 488                                          sizeof(struct ifaddrlblmsg), flags);
 489         if (!nlh)
 490                 return -EMSGSIZE;
 491
 492         ip6addrlbl_putmsg(nlh, p->prefixlen, p->ifindex, lseq);
 493
 494         if (nla_put(skb, IFAL_ADDRESS, 16, &p->prefix) < 0 ||
 495             nla_put_u32(skb, IFAL_LABEL, p->label) < 0) {
 496                 nlmsg_cancel(skb, nlh);
 497                 return -EMSGSIZE;
 498         }
 499
 500         return nlmsg_end(skb, nlh);
 501 }
 502
 503 static int ip6addrlbl_dump(struct sk_buff *skb, struct netlink_callback *cb)
 504 {
 505         struct net *net = sock_net(skb->sk);
 506         struct ip6addrlbl_entry *p;
 507         int idx = 0, s_idx = cb->args[0];
 508         int err;
 509
 510         rcu_read_lock();
 511         hlist_for_each_entry_rcu(p, &ip6addrlbl_table.head, list) {
 512                 if (idx >= s_idx &&
 513                     net_eq(ip6addrlbl_net(p), net)) {
 514                         if ((err = ip6addrlbl_fill(skb, p,
 515                                                    ip6addrlbl_table.seq,
 516                                                    NETLINK_CB(cb->skb).portid,
 517                                                    cb->nlh->nlmsg_seq,
 518                                                    RTM_NEWADDRLABEL,
 519                                                    NLM_F_MULTI)) <= 0)
 520                                 break;
 521                 }
 522                 idx++;
 523         }
 524         rcu_read_unlock();
 525         cb->args[0] = idx;
 526         return skb->len;
 527 }
 528
 529 static inline int ip6addrlbl_msgsize(void)
 530 {
 531         return NLMSG_ALIGN(sizeof(struct ifaddrlblmsg))
 532                 + nla_total_size(16)    /* IFAL_ADDRESS */
 533                 + nla_total_size(4);    /* IFAL_LABEL */
 534 }
 535
 536 static int ip6addrlbl_get(struct sk_buff *in_skb, struct nlmsghdr* nlh,
 537                           void *arg)
 538 {
 539         struct net *net = sock_net(in_skb->sk);
 540         struct ifaddrlblmsg *ifal;
 541         struct nlattr *tb[IFAL_MAX+1];
 542         struct in6_addr *addr;
 543         u32 lseq;
 544         int err = 0;
 545         struct ip6addrlbl_entry *p;
 546         struct sk_buff *skb;
 547
 548         err = nlmsg_parse(nlh, sizeof(*ifal), tb, IFAL_MAX, ifal_policy);
 549         if (err < 0)
 550                 return err;
 551
 552         ifal = nlmsg_data(nlh);
 553
 554         if (ifal->ifal_family != AF_INET6 ||
 555             ifal->ifal_prefixlen != 128)
 556                 return -EINVAL;
 557
 558         if (ifal->ifal_index &&
 559             !__dev_get_by_index(net, ifal->ifal_index))
 560                 return -EINVAL;
 561
 562         if (!tb[IFAL_ADDRESS])
 563                 return -EINVAL;
 564
 565         addr = nla_data(tb[IFAL_ADDRESS]);
 566         if (!addr)
 567                 return -EINVAL;
 568
 569         rcu_read_lock();
 570         p = __ipv6_addr_label(net, addr, ipv6_addr_type(addr), ifal->ifal_index);
 571         if (p && ip6addrlbl_hold(p))
 572                 p = NULL;
 573         lseq = ip6addrlbl_table.seq;
 574         rcu_read_unlock();
 575
 576         if (!p) {
 577                 err = -ESRCH;
 578                 goto out;
 579         }
 580
 581         if (!(skb = nlmsg_new(ip6addrlbl_msgsize(), GFP_KERNEL))) {
 582                 ip6addrlbl_put(p);
 583                 return -ENOBUFS;
 584         }
 585
 586         err = ip6addrlbl_fill(skb, p, lseq,
 587                               NETLINK_CB(in_skb).portid, nlh->nlmsg_seq,
 588                               RTM_NEWADDRLABEL, 0);
 589
 590         ip6addrlbl_put(p);
 591
 592         if (err < 0) {
 593                 WARN_ON(err == -EMSGSIZE);
 594                 kfree_skb(skb);
 595                 goto out;
 596         }
 597
 598         err = rtnl_unicast(skb, net, NETLINK_CB(in_skb).portid);
 599 out:
 600         return err;
 601 }
 602
 603 void __init ipv6_addr_label_rtnl_register(void)
 604 {
 605         __rtnl_register(PF_INET6, RTM_NEWADDRLABEL, ip6addrlbl_newdel,
 606                         NULL, NULL);
 607         __rtnl_register(PF_INET6, RTM_DELADDRLABEL, ip6addrlbl_newdel,
 608                         NULL, NULL);
 609         __rtnl_register(PF_INET6, RTM_GETADDRLABEL, ip6addrlbl_get,
 610                         ip6addrlbl_dump, NULL);
 611 }
 612