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 hlist_node *pos;
 177         struct ip6addrlbl_entry *p;
 178         hlist_for_each_entry_rcu(p, pos, &ip6addrlbl_table.head, list) {
 179                 if (__ip6addrlbl_match(net, p, addr, type, ifindex))
 180                         return p;
 181         }
 182         return NULL;
 183 }
 184
 185 u32 ipv6_addr_label(struct net *net,
 186                     const struct in6_addr *addr, int type, int ifindex)
 187 {
 188         u32 label;
 189         struct ip6addrlbl_entry *p;
 190
 191         type &= IPV6_ADDR_MAPPED | IPV6_ADDR_COMPATv4 | IPV6_ADDR_LOOPBACK;
 192
 193         rcu_read_lock();
 194         p = __ipv6_addr_label(net, addr, type, ifindex);
 195         label = p ? p->label : IPV6_ADDR_LABEL_DEFAULT;
 196         rcu_read_unlock();
 197
 198         ADDRLABEL(KERN_DEBUG "%s(addr=%pI6, type=%d, ifindex=%d) => %08x\n",
 199                   __func__, addr, type, ifindex, label);
 200
 201         return label;
 202 }
 203
 204 /* allocate one entry */
 205 static struct ip6addrlbl_entry *ip6addrlbl_alloc(struct net *net,
 206                                                  const struct in6_addr *prefix,
 207                                                  int prefixlen, int ifindex,
 208                                                  u32 label)
 209 {
 210         struct ip6addrlbl_entry *newp;
 211         int addrtype;
 212
 213         ADDRLABEL(KERN_DEBUG "%s(prefix=%pI6, prefixlen=%d, ifindex=%d, label=%u)\n",
 214                   __func__, prefix, prefixlen, ifindex, (unsigned int)label);
 215
 216         addrtype = ipv6_addr_type(prefix) & (IPV6_ADDR_MAPPED | IPV6_ADDR_COMPATv4 | IPV6_ADDR_LOOPBACK);
 217
 218         switch (addrtype) {
 219         case IPV6_ADDR_MAPPED:
 220                 if (prefixlen > 96)
 221                         return ERR_PTR(-EINVAL);
 222                 if (prefixlen < 96)
 223                         addrtype = 0;
 224                 break;
 225         case IPV6_ADDR_COMPATv4:
 226                 if (prefixlen != 96)
 227                         addrtype = 0;
 228                 break;
 229         case IPV6_ADDR_LOOPBACK:
 230                 if (prefixlen != 128)
 231                         addrtype = 0;
 232                 break;
 233         }
 234
 235         newp = kmalloc(sizeof(*newp), GFP_KERNEL);
 236         if (!newp)
 237                 return ERR_PTR(-ENOMEM);
 238
 239         ipv6_addr_prefix(&newp->prefix, prefix, prefixlen);
 240         newp->prefixlen = prefixlen;
 241         newp->ifindex = ifindex;
 242         newp->addrtype = addrtype;
 243         newp->label = label;
 244         INIT_HLIST_NODE(&newp->list);
 245 #ifdef CONFIG_NET_NS
 246         newp->lbl_net = hold_net(net);
 247 #endif
 248         atomic_set(&newp->refcnt, 1);
 249         return newp;
 250 }
 251
 252 /* add a label */
 253 static int __ip6addrlbl_add(struct ip6addrlbl_entry *newp, int replace)
 254 {
 255         int ret = 0;
 256
 257         ADDRLABEL(KERN_DEBUG "%s(newp=%p, replace=%d)\n",
 258                         __func__,
 259                         newp, replace);
 260
 261         if (hlist_empty(&ip6addrlbl_table.head)) {
 262                 hlist_add_head_rcu(&newp->list, &ip6addrlbl_table.head);
 263         } else {
 264                 struct hlist_node *pos, *n;
 265                 struct ip6addrlbl_entry *p = NULL;
 266                 hlist_for_each_entry_safe(p, pos, n,
 267                                           &ip6addrlbl_table.head, list) {
 268                         if (p->prefixlen == newp->prefixlen &&
 269                             net_eq(ip6addrlbl_net(p), ip6addrlbl_net(newp)) &&
 270                             p->ifindex == newp->ifindex &&
 271                             ipv6_addr_equal(&p->prefix, &newp->prefix)) {
 272                                 if (!replace) {
 273                                         ret = -EEXIST;
 274                                         goto out;
 275                                 }
 276                                 hlist_replace_rcu(&p->list, &newp->list);
 277                                 ip6addrlbl_put(p);
 278                                 goto out;
 279                         } else if ((p->prefixlen == newp->prefixlen && !p->ifindex) ||
 280                                    (p->prefixlen < newp->prefixlen)) {
 281                                 hlist_add_before_rcu(&newp->list, &p->list);
 282                                 goto out;
 283                         }
 284                 }
 285                 hlist_add_after_rcu(&p->list, &newp->list);
 286         }
 287 out:
 288         if (!ret)
 289                 ip6addrlbl_table.seq++;
 290         return ret;
 291 }
 292
 293 /* add a label */
 294 static int ip6addrlbl_add(struct net *net,
 295                           const struct in6_addr *prefix, int prefixlen,
 296                           int ifindex, u32 label, int replace)
 297 {
 298         struct ip6addrlbl_entry *newp;
 299         int ret = 0;
 300
 301         ADDRLABEL(KERN_DEBUG "%s(prefix=%pI6, prefixlen=%d, ifindex=%d, label=%u, replace=%d)\n",
 302                   __func__, prefix, prefixlen, ifindex, (unsigned int)label,
 303                   replace);
 304
 305         newp = ip6addrlbl_alloc(net, prefix, prefixlen, ifindex, label);
 306         if (IS_ERR(newp))
 307                 return PTR_ERR(newp);
 308         spin_lock(&ip6addrlbl_table.lock);
 309         ret = __ip6addrlbl_add(newp, replace);
 310         spin_unlock(&ip6addrlbl_table.lock);
 311         if (ret)
 312                 ip6addrlbl_free(newp);
 313         return ret;
 314 }
 315
 316 /* remove a label */
 317 static int __ip6addrlbl_del(struct net *net,
 318                             const struct in6_addr *prefix, int prefixlen,
 319                             int ifindex)
 320 {
 321         struct ip6addrlbl_entry *p = NULL;
 322         struct hlist_node *pos, *n;
 323         int ret = -ESRCH;
 324
 325         ADDRLABEL(KERN_DEBUG "%s(prefix=%pI6, prefixlen=%d, ifindex=%d)\n",
 326                   __func__, prefix, prefixlen, ifindex);
 327
 328         hlist_for_each_entry_safe(p, pos, n, &ip6addrlbl_table.head, list) {
 329                 if (p->prefixlen == prefixlen &&
 330                     net_eq(ip6addrlbl_net(p), net) &&
 331                     p->ifindex == ifindex &&
 332                     ipv6_addr_equal(&p->prefix, prefix)) {
 333                         hlist_del_rcu(&p->list);
 334                         ip6addrlbl_put(p);
 335                         ret = 0;
 336                         break;
 337                 }
 338         }
 339         return ret;
 340 }
 341
 342 static int ip6addrlbl_del(struct net *net,
 343                           const struct in6_addr *prefix, int prefixlen,
 344                           int ifindex)
 345 {
 346         struct in6_addr prefix_buf;
 347         int ret;
 348
 349         ADDRLABEL(KERN_DEBUG "%s(prefix=%pI6, prefixlen=%d, ifindex=%d)\n",
 350                   __func__, prefix, prefixlen, ifindex);
 351
 352         ipv6_addr_prefix(&prefix_buf, prefix, prefixlen);
 353         spin_lock(&ip6addrlbl_table.lock);
 354         ret = __ip6addrlbl_del(net, &prefix_buf, prefixlen, ifindex);
 355         spin_unlock(&ip6addrlbl_table.lock);
 356         return ret;
 357 }
 358
 359 /* add default label */
 360 static int __net_init ip6addrlbl_net_init(struct net *net)
 361 {
 362         int err = 0;
 363         int i;
 364
 365         ADDRLABEL(KERN_DEBUG "%s\n", __func__);
 366
 367         for (i = 0; i < ARRAY_SIZE(ip6addrlbl_init_table); i++) {
 368                 int ret = ip6addrlbl_add(net,
 369                                          ip6addrlbl_init_table[i].prefix,
 370                                          ip6addrlbl_init_table[i].prefixlen,
 371                                          0,
 372                                          ip6addrlbl_init_table[i].label, 0);
 373                 /* XXX: should we free all rules when we catch an error? */
 374                 if (ret && (!err || err != -ENOMEM))
 375                         err = ret;
 376         }
 377         return err;
 378 }
 379
 380 static void __net_exit ip6addrlbl_net_exit(struct net *net)
 381 {
 382         struct ip6addrlbl_entry *p = NULL;
 383         struct hlist_node *pos, *n;
 384
 385         /* Remove all labels belonging to the exiting net */
 386         spin_lock(&ip6addrlbl_table.lock);
 387         hlist_for_each_entry_safe(p, pos, n, &ip6addrlbl_table.head, list) {
 388                 if (net_eq(ip6addrlbl_net(p), net)) {
 389                         hlist_del_rcu(&p->list);
 390                         ip6addrlbl_put(p);
 391                 }
 392         }
 393         spin_unlock(&ip6addrlbl_table.lock);
 394 }
 395
 396 static struct pernet_operations ipv6_addr_label_ops = {
 397         .init = ip6addrlbl_net_init,
 398         .exit = ip6addrlbl_net_exit,
 399 };
 400
 401 int __init ipv6_addr_label_init(void)
 402 {
 403         spin_lock_init(&ip6addrlbl_table.lock);
 404
 405         return register_pernet_subsys(&ipv6_addr_label_ops);
 406 }
 407
 408 void ipv6_addr_label_cleanup(void)
 409 {
 410         unregister_pernet_subsys(&ipv6_addr_label_ops);
 411 }
 412
 413 static const struct nla_policy ifal_policy[IFAL_MAX+1] = {
 414         [IFAL_ADDRESS]          = { .len = sizeof(struct in6_addr), },
 415         [IFAL_LABEL]            = { .len = sizeof(u32), },
 416 };
 417
 418 static int ip6addrlbl_newdel(struct sk_buff *skb, struct nlmsghdr *nlh,
 419                              void *arg)
 420 {
 421         struct net *net = sock_net(skb->sk);
 422         struct ifaddrlblmsg *ifal;
 423         struct nlattr *tb[IFAL_MAX+1];
 424         struct in6_addr *pfx;
 425         u32 label;
 426         int err = 0;
 427
 428         err = nlmsg_parse(nlh, sizeof(*ifal), tb, IFAL_MAX, ifal_policy);
 429         if (err < 0)
 430                 return err;
 431
 432         ifal = nlmsg_data(nlh);
 433
 434         if (ifal->ifal_family != AF_INET6 ||
 435             ifal->ifal_prefixlen > 128)
 436                 return -EINVAL;
 437
 438         if (!tb[IFAL_ADDRESS])
 439                 return -EINVAL;
 440
 441         pfx = nla_data(tb[IFAL_ADDRESS]);
 442         if (!pfx)
 443                 return -EINVAL;
 444
 445         if (!tb[IFAL_LABEL])
 446                 return -EINVAL;
 447         label = nla_get_u32(tb[IFAL_LABEL]);
 448         if (label == IPV6_ADDR_LABEL_DEFAULT)
 449                 return -EINVAL;
 450
 451         switch(nlh->nlmsg_type) {
 452         case RTM_NEWADDRLABEL:
 453                 if (ifal->ifal_index &&
 454                     !__dev_get_by_index(net, ifal->ifal_index))
 455                         return -EINVAL;
 456
 457                 err = ip6addrlbl_add(net, pfx, ifal->ifal_prefixlen,
 458                                      ifal->ifal_index, label,
 459                                      nlh->nlmsg_flags & NLM_F_REPLACE);
 460                 break;
 461         case RTM_DELADDRLABEL:
 462                 err = ip6addrlbl_del(net, pfx, ifal->ifal_prefixlen,
 463                                      ifal->ifal_index);
 464                 break;
 465         default:
 466                 err = -EOPNOTSUPP;
 467         }
 468         return err;
 469 }
 470
 471 static void ip6addrlbl_putmsg(struct nlmsghdr *nlh,
 472                               int prefixlen, int ifindex, u32 lseq)
 473 {
 474         struct ifaddrlblmsg *ifal = nlmsg_data(nlh);
 475         ifal->ifal_family = AF_INET6;
 476         ifal->ifal_prefixlen = prefixlen;
 477         ifal->ifal_flags = 0;
 478         ifal->ifal_index = ifindex;
 479         ifal->ifal_seq = lseq;
 480 };
 481
 482 static int ip6addrlbl_fill(struct sk_buff *skb,
 483                            struct ip6addrlbl_entry *p,
 484                            u32 lseq,
 485                            u32 portid, u32 seq, int event,
 486                            unsigned int flags)
 487 {
 488         struct nlmsghdr *nlh = nlmsg_put(skb, portid, seq, event,
 489                                          sizeof(struct ifaddrlblmsg), flags);
 490         if (!nlh)
 491                 return -EMSGSIZE;
 492
 493         ip6addrlbl_putmsg(nlh, p->prefixlen, p->ifindex, lseq);
 494
 495         if (nla_put(skb, IFAL_ADDRESS, 16, &p->prefix) < 0 ||
 496             nla_put_u32(skb, IFAL_LABEL, p->label) < 0) {
 497                 nlmsg_cancel(skb, nlh);
 498                 return -EMSGSIZE;
 499         }
 500
 501         return nlmsg_end(skb, nlh);
 502 }
 503
 504 static int ip6addrlbl_dump(struct sk_buff *skb, struct netlink_callback *cb)
 505 {
 506         struct net *net = sock_net(skb->sk);
 507         struct ip6addrlbl_entry *p;
 508         struct hlist_node *pos;
 509         int idx = 0, s_idx = cb->args[0];
 510         int err;
 511
 512         rcu_read_lock();
 513         hlist_for_each_entry_rcu(p, pos, &ip6addrlbl_table.head, list) {
 514                 if (idx >= s_idx &&
 515                     net_eq(ip6addrlbl_net(p), net)) {
 516                         if ((err = ip6addrlbl_fill(skb, p,
 517                                                    ip6addrlbl_table.seq,
 518                                                    NETLINK_CB(cb->skb).portid,
 519                                                    cb->nlh->nlmsg_seq,
 520                                                    RTM_NEWADDRLABEL,
 521                                                    NLM_F_MULTI)) <= 0)
 522                                 break;
 523                 }
 524                 idx++;
 525         }
 526         rcu_read_unlock();
 527         cb->args[0] = idx;
 528         return skb->len;
 529 }
 530
 531 static inline int ip6addrlbl_msgsize(void)
 532 {
 533         return NLMSG_ALIGN(sizeof(struct ifaddrlblmsg))
 534                 + nla_total_size(16)    /* IFAL_ADDRESS */
 535                 + nla_total_size(4);    /* IFAL_LABEL */
 536 }
 537
 538 static int ip6addrlbl_get(struct sk_buff *in_skb, struct nlmsghdr* nlh,
 539                           void *arg)
 540 {
 541         struct net *net = sock_net(in_skb->sk);
 542         struct ifaddrlblmsg *ifal;
 543         struct nlattr *tb[IFAL_MAX+1];
 544         struct in6_addr *addr;
 545         u32 lseq;
 546         int err = 0;
 547         struct ip6addrlbl_entry *p;
 548         struct sk_buff *skb;
 549
 550         err = nlmsg_parse(nlh, sizeof(*ifal), tb, IFAL_MAX, ifal_policy);
 551         if (err < 0)
 552                 return err;
 553
 554         ifal = nlmsg_data(nlh);
 555
 556         if (ifal->ifal_family != AF_INET6 ||
 557             ifal->ifal_prefixlen != 128)
 558                 return -EINVAL;
 559
 560         if (ifal->ifal_index &&
 561             !__dev_get_by_index(net, ifal->ifal_index))
 562                 return -EINVAL;
 563
 564         if (!tb[IFAL_ADDRESS])
 565                 return -EINVAL;
 566
 567         addr = nla_data(tb[IFAL_ADDRESS]);
 568         if (!addr)
 569                 return -EINVAL;
 570
 571         rcu_read_lock();
 572         p = __ipv6_addr_label(net, addr, ipv6_addr_type(addr), ifal->ifal_index);
 573         if (p && ip6addrlbl_hold(p))
 574                 p = NULL;
 575         lseq = ip6addrlbl_table.seq;
 576         rcu_read_unlock();
 577
 578         if (!p) {
 579                 err = -ESRCH;
 580                 goto out;
 581         }
 582
 583         if (!(skb = nlmsg_new(ip6addrlbl_msgsize(), GFP_KERNEL))) {
 584                 ip6addrlbl_put(p);
 585                 return -ENOBUFS;
 586         }
 587
 588         err = ip6addrlbl_fill(skb, p, lseq,
 589                               NETLINK_CB(in_skb).portid, nlh->nlmsg_seq,
 590                               RTM_NEWADDRLABEL, 0);
 591
 592         ip6addrlbl_put(p);
 593
 594         if (err < 0) {
 595                 WARN_ON(err == -EMSGSIZE);
 596                 kfree_skb(skb);
 597                 goto out;
 598         }
 599
 600         err = rtnl_unicast(skb, net, NETLINK_CB(in_skb).portid);
 601 out:
 602         return err;
 603 }
 604
 605 void __init ipv6_addr_label_rtnl_register(void)
 606 {
 607         __rtnl_register(PF_INET6, RTM_NEWADDRLABEL, ip6addrlbl_newdel,
 608                         NULL, NULL);
 609         __rtnl_register(PF_INET6, RTM_DELADDRLABEL, ip6addrlbl_newdel,
 610                         NULL, NULL);
 611         __rtnl_register(PF_INET6, RTM_GETADDRLABEL, ip6addrlbl_get,
 612                         ip6addrlbl_dump, NULL);
 613 }
 614