net/ipv6/ip6_fib.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *      Linux INET6 implementation
   4  *      Forwarding Information Database
   5  *
   6  *      Authors:
   7  *      Pedro Roque             <roque@di.fc.ul.pt>
   8  *
   9  *      Changes:
  10  *      Yuji SEKIYA @USAGI:     Support default route on router node;
  11  *                              remove ip6_null_entry from the top of
  12  *                              routing table.
  13  *      Ville Nuorvala:         Fixed routing subtrees.
  14  */
  15
  16 #define pr_fmt(fmt) "IPv6: " fmt
  17
  18 #include <linux/errno.h>
  19 #include <linux/types.h>
  20 #include <linux/net.h>
  21 #include <linux/route.h>
  22 #include <linux/netdevice.h>
  23 #include <linux/in6.h>
  24 #include <linux/init.h>
  25 #include <linux/list.h>
  26 #include <linux/slab.h>
  27
  28 #include <net/ip.h>
  29 #include <net/ipv6.h>
  30 #include <net/ndisc.h>
  31 #include <net/addrconf.h>
  32 #include <net/lwtunnel.h>
  33 #include <net/fib_notifier.h>
  34
  35 #include <net/ip6_fib.h>
  36 #include <net/ip6_route.h>
  37
  38 static struct kmem_cache *fib6_node_kmem __read_mostly;
  39
  40 struct fib6_cleaner {
  41         struct fib6_walker w;
  42         struct net *net;
  43         int (*func)(struct fib6_info *, void *arg);
  44         int sernum;
  45         void *arg;
  46         bool skip_notify;
  47 };
  48
  49 #ifdef CONFIG_IPV6_SUBTREES
  50 #define FWS_INIT FWS_S
  51 #else
  52 #define FWS_INIT FWS_L
  53 #endif
  54
  55 static struct fib6_info *fib6_find_prefix(struct net *net,
  56                                          struct fib6_table *table,
  57                                          struct fib6_node *fn);
  58 static struct fib6_node *fib6_repair_tree(struct net *net,
  59                                           struct fib6_table *table,
  60                                           struct fib6_node *fn);
  61 static int fib6_walk(struct net *net, struct fib6_walker *w);
  62 static int fib6_walk_continue(struct fib6_walker *w);
  63
  64 /*
  65  *      A routing update causes an increase of the serial number on the
  66  *      affected subtree. This allows for cached routes to be asynchronously
  67  *      tested when modifications are made to the destination cache as a
  68  *      result of redirects, path MTU changes, etc.
  69  */
  70
  71 static void fib6_gc_timer_cb(struct timer_list *t);
  72
  73 #define FOR_WALKERS(net, w) \
  74         list_for_each_entry(w, &(net)->ipv6.fib6_walkers, lh)
  75
  76 static void fib6_walker_link(struct net *net, struct fib6_walker *w)
  77 {
  78         write_lock_bh(&net->ipv6.fib6_walker_lock);
  79         list_add(&w->lh, &net->ipv6.fib6_walkers);
  80         write_unlock_bh(&net->ipv6.fib6_walker_lock);
  81 }
  82
  83 static void fib6_walker_unlink(struct net *net, struct fib6_walker *w)
  84 {
  85         write_lock_bh(&net->ipv6.fib6_walker_lock);
  86         list_del(&w->lh);
  87         write_unlock_bh(&net->ipv6.fib6_walker_lock);
  88 }
  89
  90 static int fib6_new_sernum(struct net *net)
  91 {
  92         int new, old;
  93
  94         do {
  95                 old = atomic_read(&net->ipv6.fib6_sernum);
  96                 new = old < INT_MAX ? old + 1 : 1;
  97         } while (atomic_cmpxchg(&net->ipv6.fib6_sernum,
  98                                 old, new) != old);
  99         return new;
 100 }
 101
 102 enum {
 103         FIB6_NO_SERNUM_CHANGE = 0,
 104 };
 105
 106 void fib6_update_sernum(struct net *net, struct fib6_info *f6i)
 107 {
 108         struct fib6_node *fn;
 109
 110         fn = rcu_dereference_protected(f6i->fib6_node,
 111                         lockdep_is_held(&f6i->fib6_table->tb6_lock));
 112         if (fn)
 113                 fn->fn_sernum = fib6_new_sernum(net);
 114 }
 115
 116 /*
 117  *      Auxiliary address test functions for the radix tree.
 118  *
 119  *      These assume a 32bit processor (although it will work on
 120  *      64bit processors)
 121  */
 122
 123 /*
 124  *      test bit
 125  */
 126 #if defined(__LITTLE_ENDIAN)
 127 # define BITOP_BE32_SWIZZLE     (0x1F & ~7)
 128 #else
 129 # define BITOP_BE32_SWIZZLE     0
 130 #endif
 131
 132 static __be32 addr_bit_set(const void *token, int fn_bit)
 133 {
 134         const __be32 *addr = token;
 135         /*
 136          * Here,
 137          *      1 << ((~fn_bit ^ BITOP_BE32_SWIZZLE) & 0x1f)
 138          * is optimized version of
 139          *      htonl(1 << ((~fn_bit)&0x1F))
 140          * See include/asm-generic/bitops/le.h.
 141          */
 142         return (__force __be32)(1 << ((~fn_bit ^ BITOP_BE32_SWIZZLE) & 0x1f)) &
 143                addr[fn_bit >> 5];
 144 }
 145
 146 struct fib6_info *fib6_info_alloc(gfp_t gfp_flags, bool with_fib6_nh)
 147 {
 148         struct fib6_info *f6i;
 149         size_t sz = sizeof(*f6i);
 150
 151         if (with_fib6_nh)
 152                 sz += sizeof(struct fib6_nh);
 153
 154         f6i = kzalloc(sz, gfp_flags);
 155         if (!f6i)
 156                 return NULL;
 157
 158         /* fib6_siblings is a union with nh_list, so this initializes both */
 159         INIT_LIST_HEAD(&f6i->fib6_siblings);
 160         refcount_set(&f6i->fib6_ref, 1);
 161
 162         return f6i;
 163 }
 164
 165 void fib6_info_destroy_rcu(struct rcu_head *head)
 166 {
 167         struct fib6_info *f6i = container_of(head, struct fib6_info, rcu);
 168
 169         WARN_ON(f6i->fib6_node);
 170
 171         if (f6i->nh)
 172                 nexthop_put(f6i->nh);
 173         else
 174                 fib6_nh_release(f6i->fib6_nh);
 175
 176         ip_fib_metrics_put(f6i->fib6_metrics);
 177         kfree(f6i);
 178 }
 179 EXPORT_SYMBOL_GPL(fib6_info_destroy_rcu);
 180
 181 static struct fib6_node *node_alloc(struct net *net)
 182 {
 183         struct fib6_node *fn;
 184
 185         fn = kmem_cache_zalloc(fib6_node_kmem, GFP_ATOMIC);
 186         if (fn)
 187                 net->ipv6.rt6_stats->fib_nodes++;
 188
 189         return fn;
 190 }
 191
 192 static void node_free_immediate(struct net *net, struct fib6_node *fn)
 193 {
 194         kmem_cache_free(fib6_node_kmem, fn);
 195         net->ipv6.rt6_stats->fib_nodes--;
 196 }
 197
 198 static void node_free_rcu(struct rcu_head *head)
 199 {
 200         struct fib6_node *fn = container_of(head, struct fib6_node, rcu);
 201
 202         kmem_cache_free(fib6_node_kmem, fn);
 203 }
 204
 205 static void node_free(struct net *net, struct fib6_node *fn)
 206 {
 207         call_rcu(&fn->rcu, node_free_rcu);
 208         net->ipv6.rt6_stats->fib_nodes--;
 209 }
 210
 211 static void fib6_free_table(struct fib6_table *table)
 212 {
 213         inetpeer_invalidate_tree(&table->tb6_peers);
 214         kfree(table);
 215 }
 216
 217 static void fib6_link_table(struct net *net, struct fib6_table *tb)
 218 {
 219         unsigned int h;
 220
 221         /*
 222          * Initialize table lock at a single place to give lockdep a key,
 223          * tables aren't visible prior to being linked to the list.
 224          */
 225         spin_lock_init(&tb->tb6_lock);
 226         h = tb->tb6_id & (FIB6_TABLE_HASHSZ - 1);
 227
 228         /*
 229          * No protection necessary, this is the only list mutatation
 230          * operation, tables never disappear once they exist.
 231          */
 232         hlist_add_head_rcu(&tb->tb6_hlist, &net->ipv6.fib_table_hash[h]);
 233 }
 234
 235 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
 236
 237 static struct fib6_table *fib6_alloc_table(struct net *net, u32 id)
 238 {
 239         struct fib6_table *table;
 240
 241         table = kzalloc(sizeof(*table), GFP_ATOMIC);
 242         if (table) {
 243                 table->tb6_id = id;
 244                 rcu_assign_pointer(table->tb6_root.leaf,
 245                                    net->ipv6.fib6_null_entry);
 246                 table->tb6_root.fn_flags = RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
 247                 inet_peer_base_init(&table->tb6_peers);
 248         }
 249
 250         return table;
 251 }
 252
 253 struct fib6_table *fib6_new_table(struct net *net, u32 id)
 254 {
 255         struct fib6_table *tb;
 256
 257         if (id == 0)
 258                 id = RT6_TABLE_MAIN;
 259         tb = fib6_get_table(net, id);
 260         if (tb)
 261                 return tb;
 262
 263         tb = fib6_alloc_table(net, id);
 264         if (tb)
 265                 fib6_link_table(net, tb);
 266
 267         return tb;
 268 }
 269 EXPORT_SYMBOL_GPL(fib6_new_table);
 270
 271 struct fib6_table *fib6_get_table(struct net *net, u32 id)
 272 {
 273         struct fib6_table *tb;
 274         struct hlist_head *head;
 275         unsigned int h;
 276
 277         if (id == 0)
 278                 id = RT6_TABLE_MAIN;
 279         h = id & (FIB6_TABLE_HASHSZ - 1);
 280         rcu_read_lock();
 281         head = &net->ipv6.fib_table_hash[h];
 282         hlist_for_each_entry_rcu(tb, head, tb6_hlist) {
 283                 if (tb->tb6_id == id) {
 284                         rcu_read_unlock();
 285                         return tb;
 286                 }
 287         }
 288         rcu_read_unlock();
 289
 290         return NULL;
 291 }
 292 EXPORT_SYMBOL_GPL(fib6_get_table);
 293
 294 static void __net_init fib6_tables_init(struct net *net)
 295 {
 296         fib6_link_table(net, net->ipv6.fib6_main_tbl);
 297         fib6_link_table(net, net->ipv6.fib6_local_tbl);
 298 }
 299 #else
 300
 301 struct fib6_table *fib6_new_table(struct net *net, u32 id)
 302 {
 303         return fib6_get_table(net, id);
 304 }
 305
 306 struct fib6_table *fib6_get_table(struct net *net, u32 id)
 307 {
 308           return net->ipv6.fib6_main_tbl;
 309 }
 310
 311 struct dst_entry *fib6_rule_lookup(struct net *net, struct flowi6 *fl6,
 312                                    const struct sk_buff *skb,
 313                                    int flags, pol_lookup_t lookup)
 314 {
 315         struct rt6_info *rt;
 316
 317         rt = lookup(net, net->ipv6.fib6_main_tbl, fl6, skb, flags);
 318         if (rt->dst.error == -EAGAIN) {
 319                 ip6_rt_put_flags(rt, flags);
 320                 rt = net->ipv6.ip6_null_entry;
 321                 if (!(flags & RT6_LOOKUP_F_DST_NOREF))
 322                         dst_hold(&rt->dst);
 323         }
 324
 325         return &rt->dst;
 326 }
 327
 328 /* called with rcu lock held; no reference taken on fib6_info */
 329 int fib6_lookup(struct net *net, int oif, struct flowi6 *fl6,
 330                 struct fib6_result *res, int flags)
 331 {
 332         return fib6_table_lookup(net, net->ipv6.fib6_main_tbl, oif, fl6,
 333                                  res, flags);
 334 }
 335
 336 static void __net_init fib6_tables_init(struct net *net)
 337 {
 338         fib6_link_table(net, net->ipv6.fib6_main_tbl);
 339 }
 340
 341 #endif
 342
 343 unsigned int fib6_tables_seq_read(struct net *net)
 344 {
 345         unsigned int h, fib_seq = 0;
 346
 347         rcu_read_lock();
 348         for (h = 0; h < FIB6_TABLE_HASHSZ; h++) {
 349                 struct hlist_head *head = &net->ipv6.fib_table_hash[h];
 350                 struct fib6_table *tb;
 351
 352                 hlist_for_each_entry_rcu(tb, head, tb6_hlist)
 353                         fib_seq += tb->fib_seq;
 354         }
 355         rcu_read_unlock();
 356
 357         return fib_seq;
 358 }
 359
 360 static int call_fib6_entry_notifier(struct notifier_block *nb,
 361                                     enum fib_event_type event_type,
 362                                     struct fib6_info *rt,
 363                                     struct netlink_ext_ack *extack)
 364 {
 365         struct fib6_entry_notifier_info info = {
 366                 .info.extack = extack,
 367                 .rt = rt,
 368         };
 369
 370         return call_fib6_notifier(nb, event_type, &info.info);
 371 }
 372
 373 int call_fib6_entry_notifiers(struct net *net,
 374                               enum fib_event_type event_type,
 375                               struct fib6_info *rt,
 376                               struct netlink_ext_ack *extack)
 377 {
 378         struct fib6_entry_notifier_info info = {
 379                 .info.extack = extack,
 380                 .rt = rt,
 381         };
 382
 383         rt->fib6_table->fib_seq++;
 384         return call_fib6_notifiers(net, event_type, &info.info);
 385 }
 386
 387 int call_fib6_multipath_entry_notifiers(struct net *net,
 388                                         enum fib_event_type event_type,
 389                                         struct fib6_info *rt,
 390                                         unsigned int nsiblings,
 391                                         struct netlink_ext_ack *extack)
 392 {
 393         struct fib6_entry_notifier_info info = {
 394                 .info.extack = extack,
 395                 .rt = rt,
 396                 .nsiblings = nsiblings,
 397         };
 398
 399         rt->fib6_table->fib_seq++;
 400         return call_fib6_notifiers(net, event_type, &info.info);
 401 }
 402
 403 struct fib6_dump_arg {
 404         struct net *net;
 405         struct notifier_block *nb;
 406         struct netlink_ext_ack *extack;
 407 };
 408
 409 static int fib6_rt_dump(struct fib6_info *rt, struct fib6_dump_arg *arg)
 410 {
 411         if (rt == arg->net->ipv6.fib6_null_entry)
 412                 return 0;
 413         return call_fib6_entry_notifier(arg->nb, FIB_EVENT_ENTRY_ADD,
 414                                         rt, arg->extack);
 415 }
 416
 417 static int fib6_node_dump(struct fib6_walker *w)
 418 {
 419         struct fib6_info *rt;
 420         int err = 0;
 421
 422         for_each_fib6_walker_rt(w) {
 423                 err = fib6_rt_dump(rt, w->args);
 424                 if (err)
 425                         break;
 426         }
 427         w->leaf = NULL;
 428         return err;
 429 }
 430
 431 static int fib6_table_dump(struct net *net, struct fib6_table *tb,
 432                            struct fib6_walker *w)
 433 {
 434         int err;
 435
 436         w->root = &tb->tb6_root;
 437         spin_lock_bh(&tb->tb6_lock);
 438         err = fib6_walk(net, w);
 439         spin_unlock_bh(&tb->tb6_lock);
 440         return err;
 441 }
 442
 443 /* Called with rcu_read_lock() */
 444 int fib6_tables_dump(struct net *net, struct notifier_block *nb,
 445                      struct netlink_ext_ack *extack)
 446 {
 447         struct fib6_dump_arg arg;
 448         struct fib6_walker *w;
 449         unsigned int h;
 450         int err = 0;
 451
 452         w = kzalloc(sizeof(*w), GFP_ATOMIC);
 453         if (!w)
 454                 return -ENOMEM;
 455
 456         w->func = fib6_node_dump;
 457         arg.net = net;
 458         arg.nb = nb;
 459         arg.extack = extack;
 460         w->args = &arg;
 461
 462         for (h = 0; h < FIB6_TABLE_HASHSZ; h++) {
 463                 struct hlist_head *head = &net->ipv6.fib_table_hash[h];
 464                 struct fib6_table *tb;
 465
 466                 hlist_for_each_entry_rcu(tb, head, tb6_hlist) {
 467                         err = fib6_table_dump(net, tb, w);
 468                         if (err < 0)
 469                                 goto out;
 470                 }
 471         }
 472
 473 out:
 474         kfree(w);
 475
 476         return err;
 477 }
 478
 479 static int fib6_dump_node(struct fib6_walker *w)
 480 {
 481         int res;
 482         struct fib6_info *rt;
 483
 484         for_each_fib6_walker_rt(w) {
 485                 res = rt6_dump_route(rt, w->args, w->skip_in_node);
 486                 if (res >= 0) {
 487                         /* Frame is full, suspend walking */
 488                         w->leaf = rt;
 489
 490                         /* We'll restart from this node, so if some routes were
 491                          * already dumped, skip them next time.
 492                          */
 493                         w->skip_in_node += res;
 494
 495                         return 1;
 496                 }
 497                 w->skip_in_node = 0;
 498
 499                 /* Multipath routes are dumped in one route with the
 500                  * RTA_MULTIPATH attribute. Jump 'rt' to point to the
 501                  * last sibling of this route (no need to dump the
 502                  * sibling routes again)
 503                  */
 504                 if (rt->fib6_nsiblings)
 505                         rt = list_last_entry(&rt->fib6_siblings,
 506                                              struct fib6_info,
 507                                              fib6_siblings);
 508         }
 509         w->leaf = NULL;
 510         return 0;
 511 }
 512
 513 static void fib6_dump_end(struct netlink_callback *cb)
 514 {
 515         struct net *net = sock_net(cb->skb->sk);
 516         struct fib6_walker *w = (void *)cb->args[2];
 517
 518         if (w) {
 519                 if (cb->args[4]) {
 520                         cb->args[4] = 0;
 521                         fib6_walker_unlink(net, w);
 522                 }
 523                 cb->args[2] = 0;
 524                 kfree(w);
 525         }
 526         cb->done = (void *)cb->args[3];
 527         cb->args[1] = 3;
 528 }
 529
 530 static int fib6_dump_done(struct netlink_callback *cb)
 531 {
 532         fib6_dump_end(cb);
 533         return cb->done ? cb->done(cb) : 0;
 534 }
 535
 536 static int fib6_dump_table(struct fib6_table *table, struct sk_buff *skb,
 537                            struct netlink_callback *cb)
 538 {
 539         struct net *net = sock_net(skb->sk);
 540         struct fib6_walker *w;
 541         int res;
 542
 543         w = (void *)cb->args[2];
 544         w->root = &table->tb6_root;
 545
 546         if (cb->args[4] == 0) {
 547                 w->count = 0;
 548                 w->skip = 0;
 549                 w->skip_in_node = 0;
 550
 551                 spin_lock_bh(&table->tb6_lock);
 552                 res = fib6_walk(net, w);
 553                 spin_unlock_bh(&table->tb6_lock);
 554                 if (res > 0) {
 555                         cb->args[4] = 1;
 556                         cb->args[5] = w->root->fn_sernum;
 557                 }
 558         } else {
 559                 if (cb->args[5] != w->root->fn_sernum) {
 560                         /* Begin at the root if the tree changed */
 561                         cb->args[5] = w->root->fn_sernum;
 562                         w->state = FWS_INIT;
 563                         w->node = w->root;
 564                         w->skip = w->count;
 565                         w->skip_in_node = 0;
 566                 } else
 567                         w->skip = 0;
 568
 569                 spin_lock_bh(&table->tb6_lock);
 570                 res = fib6_walk_continue(w);
 571                 spin_unlock_bh(&table->tb6_lock);
 572                 if (res <= 0) {
 573                         fib6_walker_unlink(net, w);
 574                         cb->args[4] = 0;
 575                 }
 576         }
 577
 578         return res;
 579 }
 580
 581 static int inet6_dump_fib(struct sk_buff *skb, struct netlink_callback *cb)
 582 {
 583         struct rt6_rtnl_dump_arg arg = { .filter.dump_exceptions = true,
 584                                          .filter.dump_routes = true };
 585         const struct nlmsghdr *nlh = cb->nlh;
 586         struct net *net = sock_net(skb->sk);
 587         unsigned int h, s_h;
 588         unsigned int e = 0, s_e;
 589         struct fib6_walker *w;
 590         struct fib6_table *tb;
 591         struct hlist_head *head;
 592         int res = 0;
 593
 594         if (cb->strict_check) {
 595                 int err;
 596
 597                 err = ip_valid_fib_dump_req(net, nlh, &arg.filter, cb);
 598                 if (err < 0)
 599                         return err;
 600         } else if (nlmsg_len(nlh) >= sizeof(struct rtmsg)) {
 601                 struct rtmsg *rtm = nlmsg_data(nlh);
 602
 603                 if (rtm->rtm_flags & RTM_F_PREFIX)
 604                         arg.filter.flags = RTM_F_PREFIX;
 605         }
 606
 607         w = (void *)cb->args[2];
 608         if (!w) {
 609                 /* New dump:
 610                  *
 611                  * 1. hook callback destructor.
 612                  */
 613                 cb->args[3] = (long)cb->done;
 614                 cb->done = fib6_dump_done;
 615
 616                 /*
 617                  * 2. allocate and initialize walker.
 618                  */
 619                 w = kzalloc(sizeof(*w), GFP_ATOMIC);
 620                 if (!w)
 621                         return -ENOMEM;
 622                 w->func = fib6_dump_node;
 623                 cb->args[2] = (long)w;
 624         }
 625
 626         arg.skb = skb;
 627         arg.cb = cb;
 628         arg.net = net;
 629         w->args = &arg;
 630
 631         if (arg.filter.table_id) {
 632                 tb = fib6_get_table(net, arg.filter.table_id);
 633                 if (!tb) {
 634                         if (arg.filter.dump_all_families)
 635                                 goto out;
 636
 637                         NL_SET_ERR_MSG_MOD(cb->extack, "FIB table does not exist");
 638                         return -ENOENT;
 639                 }
 640
 641                 if (!cb->args[0]) {
 642                         res = fib6_dump_table(tb, skb, cb);
 643                         if (!res)
 644                                 cb->args[0] = 1;
 645                 }
 646                 goto out;
 647         }
 648
 649         s_h = cb->args[0];
 650         s_e = cb->args[1];
 651
 652         rcu_read_lock();
 653         for (h = s_h; h < FIB6_TABLE_HASHSZ; h++, s_e = 0) {
 654                 e = 0;
 655                 head = &net->ipv6.fib_table_hash[h];
 656                 hlist_for_each_entry_rcu(tb, head, tb6_hlist) {
 657                         if (e < s_e)
 658                                 goto next;
 659                         res = fib6_dump_table(tb, skb, cb);
 660                         if (res != 0)
 661                                 goto out_unlock;
 662 next:
 663                         e++;
 664                 }
 665         }
 666 out_unlock:
 667         rcu_read_unlock();
 668         cb->args[1] = e;
 669         cb->args[0] = h;
 670 out:
 671         res = res < 0 ? res : skb->len;
 672         if (res <= 0)
 673                 fib6_dump_end(cb);
 674         return res;
 675 }
 676
 677 void fib6_metric_set(struct fib6_info *f6i, int metric, u32 val)
 678 {
 679         if (!f6i)
 680                 return;
 681
 682         if (f6i->fib6_metrics == &dst_default_metrics) {
 683                 struct dst_metrics *p = kzalloc(sizeof(*p), GFP_ATOMIC);
 684
 685                 if (!p)
 686                         return;
 687
 688                 refcount_set(&p->refcnt, 1);
 689                 f6i->fib6_metrics = p;
 690         }
 691
 692         f6i->fib6_metrics->metrics[metric - 1] = val;
 693 }
 694
 695 /*
 696  *      Routing Table
 697  *
 698  *      return the appropriate node for a routing tree "add" operation
 699  *      by either creating and inserting or by returning an existing
 700  *      node.
 701  */
 702
 703 static struct fib6_node *fib6_add_1(struct net *net,
 704                                     struct fib6_table *table,
 705                                     struct fib6_node *root,
 706                                     struct in6_addr *addr, int plen,
 707                                     int offset, int allow_create,
 708                                     int replace_required,
 709                                     struct netlink_ext_ack *extack)
 710 {
 711         struct fib6_node *fn, *in, *ln;
 712         struct fib6_node *pn = NULL;
 713         struct rt6key *key;
 714         int     bit;
 715         __be32  dir = 0;
 716
 717         RT6_TRACE("fib6_add_1\n");
 718
 719         /* insert node in tree */
 720
 721         fn = root;
 722
 723         do {
 724                 struct fib6_info *leaf = rcu_dereference_protected(fn->leaf,
 725                                             lockdep_is_held(&table->tb6_lock));
 726                 key = (struct rt6key *)((u8 *)leaf + offset);
 727
 728                 /*
 729                  *      Prefix match
 730                  */
 731                 if (plen < fn->fn_bit ||
 732                     !ipv6_prefix_equal(&key->addr, addr, fn->fn_bit)) {
 733                         if (!allow_create) {
 734                                 if (replace_required) {
 735                                         NL_SET_ERR_MSG(extack,
 736                                                        "Can not replace route - no match found");
 737                                         pr_warn("Can't replace route, no match found\n");
 738                                         return ERR_PTR(-ENOENT);
 739                                 }
 740                                 pr_warn("NLM_F_CREATE should be set when creating new route\n");
 741                         }
 742                         goto insert_above;
 743                 }
 744
 745                 /*
 746                  *      Exact match ?
 747                  */
 748
 749                 if (plen == fn->fn_bit) {
 750                         /* clean up an intermediate node */
 751                         if (!(fn->fn_flags & RTN_RTINFO)) {
 752                                 RCU_INIT_POINTER(fn->leaf, NULL);
 753                                 fib6_info_release(leaf);
 754                         /* remove null_entry in the root node */
 755                         } else if (fn->fn_flags & RTN_TL_ROOT &&
 756                                    rcu_access_pointer(fn->leaf) ==
 757                                    net->ipv6.fib6_null_entry) {
 758                                 RCU_INIT_POINTER(fn->leaf, NULL);
 759                         }
 760
 761                         return fn;
 762                 }
 763
 764                 /*
 765                  *      We have more bits to go
 766                  */
 767
 768                 /* Try to walk down on tree. */
 769                 dir = addr_bit_set(addr, fn->fn_bit);
 770                 pn = fn;
 771                 fn = dir ?
 772                      rcu_dereference_protected(fn->right,
 773                                         lockdep_is_held(&table->tb6_lock)) :
 774                      rcu_dereference_protected(fn->left,
 775                                         lockdep_is_held(&table->tb6_lock));
 776         } while (fn);
 777
 778         if (!allow_create) {
 779                 /* We should not create new node because
 780                  * NLM_F_REPLACE was specified without NLM_F_CREATE
 781                  * I assume it is safe to require NLM_F_CREATE when
 782                  * REPLACE flag is used! Later we may want to remove the
 783                  * check for replace_required, because according
 784                  * to netlink specification, NLM_F_CREATE
 785                  * MUST be specified if new route is created.
 786                  * That would keep IPv6 consistent with IPv4
 787                  */
 788                 if (replace_required) {
 789                         NL_SET_ERR_MSG(extack,
 790                                        "Can not replace route - no match found");
 791                         pr_warn("Can't replace route, no match found\n");
 792                         return ERR_PTR(-ENOENT);
 793                 }
 794                 pr_warn("NLM_F_CREATE should be set when creating new route\n");
 795         }
 796         /*
 797          *      We walked to the bottom of tree.
 798          *      Create new leaf node without children.
 799          */
 800
 801         ln = node_alloc(net);
 802
 803         if (!ln)
 804                 return ERR_PTR(-ENOMEM);
 805         ln->fn_bit = plen;
 806         RCU_INIT_POINTER(ln->parent, pn);
 807
 808         if (dir)
 809                 rcu_assign_pointer(pn->right, ln);
 810         else
 811                 rcu_assign_pointer(pn->left, ln);
 812
 813         return ln;
 814
 815
 816 insert_above:
 817         /*
 818          * split since we don't have a common prefix anymore or
 819          * we have a less significant route.
 820          * we've to insert an intermediate node on the list
 821          * this new node will point to the one we need to create
 822          * and the current
 823          */
 824
 825         pn = rcu_dereference_protected(fn->parent,
 826                                        lockdep_is_held(&table->tb6_lock));
 827
 828         /* find 1st bit in difference between the 2 addrs.
 829
 830            See comment in __ipv6_addr_diff: bit may be an invalid value,
 831            but if it is >= plen, the value is ignored in any case.
 832          */
 833
 834         bit = __ipv6_addr_diff(addr, &key->addr, sizeof(*addr));
 835
 836         /*
 837          *              (intermediate)[in]
 838          *                /        \
 839          *      (new leaf node)[ln] (old node)[fn]
 840          */
 841         if (plen > bit) {
 842                 in = node_alloc(net);
 843                 ln = node_alloc(net);
 844
 845                 if (!in || !ln) {
 846                         if (in)
 847                                 node_free_immediate(net, in);
 848                         if (ln)
 849                                 node_free_immediate(net, ln);
 850                         return ERR_PTR(-ENOMEM);
 851                 }
 852
 853                 /*
 854                  * new intermediate node.
 855                  * RTN_RTINFO will
 856                  * be off since that an address that chooses one of
 857                  * the branches would not match less specific routes
 858                  * in the other branch
 859                  */
 860
 861                 in->fn_bit = bit;
 862
 863                 RCU_INIT_POINTER(in->parent, pn);
 864                 in->leaf = fn->leaf;
 865                 fib6_info_hold(rcu_dereference_protected(in->leaf,
 866                                 lockdep_is_held(&table->tb6_lock)));
 867
 868                 /* update parent pointer */
 869                 if (dir)
 870                         rcu_assign_pointer(pn->right, in);
 871                 else
 872                         rcu_assign_pointer(pn->left, in);
 873
 874                 ln->fn_bit = plen;
 875
 876                 RCU_INIT_POINTER(ln->parent, in);
 877                 rcu_assign_pointer(fn->parent, in);
 878
 879                 if (addr_bit_set(addr, bit)) {
 880                         rcu_assign_pointer(in->right, ln);
 881                         rcu_assign_pointer(in->left, fn);
 882                 } else {
 883                         rcu_assign_pointer(in->left, ln);
 884                         rcu_assign_pointer(in->right, fn);
 885                 }
 886         } else { /* plen <= bit */
 887
 888                 /*
 889                  *              (new leaf node)[ln]
 890                  *                /        \
 891                  *           (old node)[fn] NULL
 892                  */
 893
 894                 ln = node_alloc(net);
 895
 896                 if (!ln)
 897                         return ERR_PTR(-ENOMEM);
 898
 899                 ln->fn_bit = plen;
 900
 901                 RCU_INIT_POINTER(ln->parent, pn);
 902
 903                 if (addr_bit_set(&key->addr, plen))
 904                         RCU_INIT_POINTER(ln->right, fn);
 905                 else
 906                         RCU_INIT_POINTER(ln->left, fn);
 907
 908                 rcu_assign_pointer(fn->parent, ln);
 909
 910                 if (dir)
 911                         rcu_assign_pointer(pn->right, ln);
 912                 else
 913                         rcu_assign_pointer(pn->left, ln);
 914         }
 915         return ln;
 916 }
 917
 918 static void __fib6_drop_pcpu_from(struct fib6_nh *fib6_nh,
 919                                   const struct fib6_info *match,
 920                                   const struct fib6_table *table)
 921 {
 922         int cpu;
 923
 924         if (!fib6_nh->rt6i_pcpu)
 925                 return;
 926
 927         /* release the reference to this fib entry from
 928          * all of its cached pcpu routes
 929          */
 930         for_each_possible_cpu(cpu) {
 931                 struct rt6_info **ppcpu_rt;
 932                 struct rt6_info *pcpu_rt;
 933
 934                 ppcpu_rt = per_cpu_ptr(fib6_nh->rt6i_pcpu, cpu);
 935                 pcpu_rt = *ppcpu_rt;
 936
 937                 /* only dropping the 'from' reference if the cached route
 938                  * is using 'match'. The cached pcpu_rt->from only changes
 939                  * from a fib6_info to NULL (ip6_dst_destroy); it can never
 940                  * change from one fib6_info reference to another
 941                  */
 942                 if (pcpu_rt && rcu_access_pointer(pcpu_rt->from) == match) {
 943                         struct fib6_info *from;
 944
 945                         from = xchg((__force struct fib6_info **)&pcpu_rt->from, NULL);
 946                         fib6_info_release(from);
 947                 }
 948         }
 949 }
 950
 951 struct fib6_nh_pcpu_arg {
 952         struct fib6_info        *from;
 953         const struct fib6_table *table;
 954 };
 955
 956 static int fib6_nh_drop_pcpu_from(struct fib6_nh *nh, void *_arg)
 957 {
 958         struct fib6_nh_pcpu_arg *arg = _arg;
 959
 960         __fib6_drop_pcpu_from(nh, arg->from, arg->table);
 961         return 0;
 962 }
 963
 964 static void fib6_drop_pcpu_from(struct fib6_info *f6i,
 965                                 const struct fib6_table *table)
 966 {
 967         /* Make sure rt6_make_pcpu_route() wont add other percpu routes
 968          * while we are cleaning them here.
 969          */
 970         f6i->fib6_destroying = 1;
 971         mb(); /* paired with the cmpxchg() in rt6_make_pcpu_route() */
 972
 973         if (f6i->nh) {
 974                 struct fib6_nh_pcpu_arg arg = {
 975                         .from = f6i,
 976                         .table = table
 977                 };
 978
 979                 nexthop_for_each_fib6_nh(f6i->nh, fib6_nh_drop_pcpu_from,
 980                                          &arg);
 981         } else {
 982                 struct fib6_nh *fib6_nh;
 983
 984                 fib6_nh = f6i->fib6_nh;
 985                 __fib6_drop_pcpu_from(fib6_nh, f6i, table);
 986         }
 987 }
 988
 989 static void fib6_purge_rt(struct fib6_info *rt, struct fib6_node *fn,
 990                           struct net *net)
 991 {
 992         struct fib6_table *table = rt->fib6_table;
 993
 994         fib6_drop_pcpu_from(rt, table);
 995
 996         if (rt->nh && !list_empty(&rt->nh_list))
 997                 list_del_init(&rt->nh_list);
 998
 999         if (refcount_read(&rt->fib6_ref) != 1) {
1000                 /* This route is used as dummy address holder in some split
1001                  * nodes. It is not leaked, but it still holds other resources,
1002                  * which must be released in time. So, scan ascendant nodes
1003                  * and replace dummy references to this route with references
1004                  * to still alive ones.
1005                  */
1006                 while (fn) {
1007                         struct fib6_info *leaf = rcu_dereference_protected(fn->leaf,
1008                                             lockdep_is_held(&table->tb6_lock));
1009                         struct fib6_info *new_leaf;
1010                         if (!(fn->fn_flags & RTN_RTINFO) && leaf == rt) {
1011                                 new_leaf = fib6_find_prefix(net, table, fn);
1012                                 fib6_info_hold(new_leaf);
1013
1014                                 rcu_assign_pointer(fn->leaf, new_leaf);
1015                                 fib6_info_release(rt);
1016                         }
1017                         fn = rcu_dereference_protected(fn->parent,
1018                                     lockdep_is_held(&table->tb6_lock));
1019                 }
1020         }
1021 }
1022
1023 /*
1024  *      Insert routing information in a node.
1025  */
1026
1027 static int fib6_add_rt2node(struct fib6_node *fn, struct fib6_info *rt,
1028                             struct nl_info *info,
1029                             struct netlink_ext_ack *extack)
1030 {
1031         struct fib6_info *leaf = rcu_dereference_protected(fn->leaf,
1032                                     lockdep_is_held(&rt->fib6_table->tb6_lock));
1033         struct fib6_info *iter = NULL;
1034         struct fib6_info __rcu **ins;
1035         struct fib6_info __rcu **fallback_ins = NULL;
1036         int replace = (info->nlh &&
1037                        (info->nlh->nlmsg_flags & NLM_F_REPLACE));
1038         int add = (!info->nlh ||
1039                    (info->nlh->nlmsg_flags & NLM_F_CREATE));
1040         int found = 0;
1041         bool rt_can_ecmp = rt6_qualify_for_ecmp(rt);
1042         u16 nlflags = NLM_F_EXCL;
1043         int err;
1044
1045         if (info->nlh && (info->nlh->nlmsg_flags & NLM_F_APPEND))
1046                 nlflags |= NLM_F_APPEND;
1047
1048         ins = &fn->leaf;
1049
1050         for (iter = leaf; iter;
1051              iter = rcu_dereference_protected(iter->fib6_next,
1052                                 lockdep_is_held(&rt->fib6_table->tb6_lock))) {
1053                 /*
1054                  *      Search for duplicates
1055                  */
1056
1057                 if (iter->fib6_metric == rt->fib6_metric) {
1058                         /*
1059                          *      Same priority level
1060                          */
1061                         if (info->nlh &&
1062                             (info->nlh->nlmsg_flags & NLM_F_EXCL))
1063                                 return -EEXIST;
1064
1065                         nlflags &= ~NLM_F_EXCL;
1066                         if (replace) {
1067                                 if (rt_can_ecmp == rt6_qualify_for_ecmp(iter)) {
1068                                         found++;
1069                                         break;
1070                                 }
1071                                 if (rt_can_ecmp)
1072                                         fallback_ins = fallback_ins ?: ins;
1073                                 goto next_iter;
1074                         }
1075
1076                         if (rt6_duplicate_nexthop(iter, rt)) {
1077                                 if (rt->fib6_nsiblings)
1078                                         rt->fib6_nsiblings = 0;
1079                                 if (!(iter->fib6_flags & RTF_EXPIRES))
1080                                         return -EEXIST;
1081                                 if (!(rt->fib6_flags & RTF_EXPIRES))
1082                                         fib6_clean_expires(iter);
1083                                 else
1084                                         fib6_set_expires(iter, rt->expires);
1085
1086                                 if (rt->fib6_pmtu)
1087                                         fib6_metric_set(iter, RTAX_MTU,
1088                                                         rt->fib6_pmtu);
1089                                 return -EEXIST;
1090                         }
1091                         /* If we have the same destination and the same metric,
1092                          * but not the same gateway, then the route we try to
1093                          * add is sibling to this route, increment our counter
1094                          * of siblings, and later we will add our route to the
1095                          * list.
1096                          * Only static routes (which don't have flag
1097                          * RTF_EXPIRES) are used for ECMPv6.
1098                          *
1099                          * To avoid long list, we only had siblings if the
1100                          * route have a gateway.
1101                          */
1102                         if (rt_can_ecmp &&
1103                             rt6_qualify_for_ecmp(iter))
1104                                 rt->fib6_nsiblings++;
1105                 }
1106
1107                 if (iter->fib6_metric > rt->fib6_metric)
1108                         break;
1109
1110 next_iter:
1111                 ins = &iter->fib6_next;
1112         }
1113
1114         if (fallback_ins && !found) {
1115                 /* No ECMP-able route found, replace first non-ECMP one */
1116                 ins = fallback_ins;
1117                 iter = rcu_dereference_protected(*ins,
1118                                     lockdep_is_held(&rt->fib6_table->tb6_lock));
1119                 found++;
1120         }
1121
1122         /* Reset round-robin state, if necessary */
1123         if (ins == &fn->leaf)
1124                 fn->rr_ptr = NULL;
1125
1126         /* Link this route to others same route. */
1127         if (rt->fib6_nsiblings) {
1128                 unsigned int fib6_nsiblings;
1129                 struct fib6_info *sibling, *temp_sibling;
1130
1131                 /* Find the first route that have the same metric */
1132                 sibling = leaf;
1133                 while (sibling) {
1134                         if (sibling->fib6_metric == rt->fib6_metric &&
1135                             rt6_qualify_for_ecmp(sibling)) {
1136                                 list_add_tail(&rt->fib6_siblings,
1137                                               &sibling->fib6_siblings);
1138                                 break;
1139                         }
1140                         sibling = rcu_dereference_protected(sibling->fib6_next,
1141                                     lockdep_is_held(&rt->fib6_table->tb6_lock));
1142                 }
1143                 /* For each sibling in the list, increment the counter of
1144                  * siblings. BUG() if counters does not match, list of siblings
1145                  * is broken!
1146                  */
1147                 fib6_nsiblings = 0;
1148                 list_for_each_entry_safe(sibling, temp_sibling,
1149                                          &rt->fib6_siblings, fib6_siblings) {
1150                         sibling->fib6_nsiblings++;
1151                         BUG_ON(sibling->fib6_nsiblings != rt->fib6_nsiblings);
1152                         fib6_nsiblings++;
1153                 }
1154                 BUG_ON(fib6_nsiblings != rt->fib6_nsiblings);
1155                 rt6_multipath_rebalance(temp_sibling);
1156         }
1157
1158         /*
1159          *      insert node
1160          */
1161         if (!replace) {
1162                 if (!add)
1163                         pr_warn("NLM_F_CREATE should be set when creating new route\n");
1164
1165 add:
1166                 nlflags |= NLM_F_CREATE;
1167
1168                 if (!info->skip_notify_kernel) {
1169                         err = call_fib6_entry_notifiers(info->nl_net,
1170                                                         FIB_EVENT_ENTRY_ADD,
1171                                                         rt, extack);
1172                         if (err) {
1173                                 struct fib6_info *sibling, *next_sibling;
1174
1175                                 /* If the route has siblings, then it first
1176                                  * needs to be unlinked from them.
1177                                  */
1178                                 if (!rt->fib6_nsiblings)
1179                                         return err;
1180
1181                                 list_for_each_entry_safe(sibling, next_sibling,
1182                                                          &rt->fib6_siblings,
1183                                                          fib6_siblings)
1184                                         sibling->fib6_nsiblings--;
1185                                 rt->fib6_nsiblings = 0;
1186                                 list_del_init(&rt->fib6_siblings);
1187                                 rt6_multipath_rebalance(next_sibling);
1188                                 return err;
1189                         }
1190                 }
1191
1192                 rcu_assign_pointer(rt->fib6_next, iter);
1193                 fib6_info_hold(rt);
1194                 rcu_assign_pointer(rt->fib6_node, fn);
1195                 rcu_assign_pointer(*ins, rt);
1196                 if (!info->skip_notify)
1197                         inet6_rt_notify(RTM_NEWROUTE, rt, info, nlflags);
1198                 info->nl_net->ipv6.rt6_stats->fib_rt_entries++;
1199
1200                 if (!(fn->fn_flags & RTN_RTINFO)) {
1201                         info->nl_net->ipv6.rt6_stats->fib_route_nodes++;
1202                         fn->fn_flags |= RTN_RTINFO;
1203                 }
1204
1205         } else {
1206                 int nsiblings;
1207
1208                 if (!found) {
1209                         if (add)
1210                                 goto add;
1211                         pr_warn("NLM_F_REPLACE set, but no existing node found!\n");
1212                         return -ENOENT;
1213                 }
1214
1215                 if (!info->skip_notify_kernel) {
1216                         err = call_fib6_entry_notifiers(info->nl_net,
1217                                                         FIB_EVENT_ENTRY_REPLACE,
1218                                                         rt, extack);
1219                         if (err)
1220                                 return err;
1221                 }
1222
1223                 fib6_info_hold(rt);
1224                 rcu_assign_pointer(rt->fib6_node, fn);
1225                 rt->fib6_next = iter->fib6_next;
1226                 rcu_assign_pointer(*ins, rt);
1227                 if (!info->skip_notify)
1228                         inet6_rt_notify(RTM_NEWROUTE, rt, info, NLM_F_REPLACE);
1229                 if (!(fn->fn_flags & RTN_RTINFO)) {
1230                         info->nl_net->ipv6.rt6_stats->fib_route_nodes++;
1231                         fn->fn_flags |= RTN_RTINFO;
1232                 }
1233                 nsiblings = iter->fib6_nsiblings;
1234                 iter->fib6_node = NULL;
1235                 fib6_purge_rt(iter, fn, info->nl_net);
1236                 if (rcu_access_pointer(fn->rr_ptr) == iter)
1237                         fn->rr_ptr = NULL;
1238                 fib6_info_release(iter);
1239
1240                 if (nsiblings) {
1241                         /* Replacing an ECMP route, remove all siblings */
1242                         ins = &rt->fib6_next;
1243                         iter = rcu_dereference_protected(*ins,
1244                                     lockdep_is_held(&rt->fib6_table->tb6_lock));
1245                         while (iter) {
1246                                 if (iter->fib6_metric > rt->fib6_metric)
1247                                         break;
1248                                 if (rt6_qualify_for_ecmp(iter)) {
1249                                         *ins = iter->fib6_next;
1250                                         iter->fib6_node = NULL;
1251                                         fib6_purge_rt(iter, fn, info->nl_net);
1252                                         if (rcu_access_pointer(fn->rr_ptr) == iter)
1253                                                 fn->rr_ptr = NULL;
1254                                         fib6_info_release(iter);
1255                                         nsiblings--;
1256                                         info->nl_net->ipv6.rt6_stats->fib_rt_entries--;
1257                                 } else {
1258                                         ins = &iter->fib6_next;
1259                                 }
1260                                 iter = rcu_dereference_protected(*ins,
1261                                         lockdep_is_held(&rt->fib6_table->tb6_lock));
1262                         }
1263                         WARN_ON(nsiblings != 0);
1264                 }
1265         }
1266
1267         return 0;
1268 }
1269
1270 static void fib6_start_gc(struct net *net, struct fib6_info *rt)
1271 {
1272         if (!timer_pending(&net->ipv6.ip6_fib_timer) &&
1273             (rt->fib6_flags & RTF_EXPIRES))
1274                 mod_timer(&net->ipv6.ip6_fib_timer,
1275                           jiffies + net->ipv6.sysctl.ip6_rt_gc_interval);
1276 }
1277
1278 void fib6_force_start_gc(struct net *net)
1279 {
1280         if (!timer_pending(&net->ipv6.ip6_fib_timer))
1281                 mod_timer(&net->ipv6.ip6_fib_timer,
1282                           jiffies + net->ipv6.sysctl.ip6_rt_gc_interval);
1283 }
1284
1285 static void __fib6_update_sernum_upto_root(struct fib6_info *rt,
1286                                            int sernum)
1287 {
1288         struct fib6_node *fn = rcu_dereference_protected(rt->fib6_node,
1289                                 lockdep_is_held(&rt->fib6_table->tb6_lock));
1290
1291         /* paired with smp_rmb() in rt6_get_cookie_safe() */
1292         smp_wmb();
1293         while (fn) {
1294                 fn->fn_sernum = sernum;
1295                 fn = rcu_dereference_protected(fn->parent,
1296                                 lockdep_is_held(&rt->fib6_table->tb6_lock));
1297         }
1298 }
1299
1300 void fib6_update_sernum_upto_root(struct net *net, struct fib6_info *rt)
1301 {
1302         __fib6_update_sernum_upto_root(rt, fib6_new_sernum(net));
1303 }
1304
1305 /* allow ipv4 to update sernum via ipv6_stub */
1306 void fib6_update_sernum_stub(struct net *net, struct fib6_info *f6i)
1307 {
1308         spin_lock_bh(&f6i->fib6_table->tb6_lock);
1309         fib6_update_sernum_upto_root(net, f6i);
1310         spin_unlock_bh(&f6i->fib6_table->tb6_lock);
1311 }
1312
1313 /*
1314  *      Add routing information to the routing tree.
1315  *      <destination addr>/<source addr>
1316  *      with source addr info in sub-trees
1317  *      Need to own table->tb6_lock
1318  */
1319
1320 int fib6_add(struct fib6_node *root, struct fib6_info *rt,
1321              struct nl_info *info, struct netlink_ext_ack *extack)
1322 {
1323         struct fib6_table *table = rt->fib6_table;
1324         struct fib6_node *fn, *pn = NULL;
1325         int err = -ENOMEM;
1326         int allow_create = 1;
1327         int replace_required = 0;
1328         int sernum = fib6_new_sernum(info->nl_net);
1329
1330         if (info->nlh) {
1331                 if (!(info->nlh->nlmsg_flags & NLM_F_CREATE))
1332                         allow_create = 0;
1333                 if (info->nlh->nlmsg_flags & NLM_F_REPLACE)
1334                         replace_required = 1;
1335         }
1336         if (!allow_create && !replace_required)
1337                 pr_warn("RTM_NEWROUTE with no NLM_F_CREATE or NLM_F_REPLACE\n");
1338
1339         fn = fib6_add_1(info->nl_net, table, root,
1340                         &rt->fib6_dst.addr, rt->fib6_dst.plen,
1341                         offsetof(struct fib6_info, fib6_dst), allow_create,
1342                         replace_required, extack);
1343         if (IS_ERR(fn)) {
1344                 err = PTR_ERR(fn);
1345                 fn = NULL;
1346                 goto out;
1347         }
1348
1349         pn = fn;
1350
1351 #ifdef CONFIG_IPV6_SUBTREES
1352         if (rt->fib6_src.plen) {
1353                 struct fib6_node *sn;
1354
1355                 if (!rcu_access_pointer(fn->subtree)) {
1356                         struct fib6_node *sfn;
1357
1358                         /*
1359                          * Create subtree.
1360                          *
1361                          *              fn[main tree]
1362                          *              |
1363                          *              sfn[subtree root]
1364                          *                 \
1365                          *                  sn[new leaf node]
1366                          */
1367
1368                         /* Create subtree root node */
1369                         sfn = node_alloc(info->nl_net);
1370                         if (!sfn)
1371                                 goto failure;
1372
1373                         fib6_info_hold(info->nl_net->ipv6.fib6_null_entry);
1374                         rcu_assign_pointer(sfn->leaf,
1375                                            info->nl_net->ipv6.fib6_null_entry);
1376                         sfn->fn_flags = RTN_ROOT;
1377
1378                         /* Now add the first leaf node to new subtree */
1379
1380                         sn = fib6_add_1(info->nl_net, table, sfn,
1381                                         &rt->fib6_src.addr, rt->fib6_src.plen,
1382                                         offsetof(struct fib6_info, fib6_src),
1383                                         allow_create, replace_required, extack);
1384
1385                         if (IS_ERR(sn)) {
1386                                 /* If it is failed, discard just allocated
1387                                    root, and then (in failure) stale node
1388                                    in main tree.
1389                                  */
1390                                 node_free_immediate(info->nl_net, sfn);
1391                                 err = PTR_ERR(sn);
1392                                 goto failure;
1393                         }
1394
1395                         /* Now link new subtree to main tree */
1396                         rcu_assign_pointer(sfn->parent, fn);
1397                         rcu_assign_pointer(fn->subtree, sfn);
1398                 } else {
1399                         sn = fib6_add_1(info->nl_net, table, FIB6_SUBTREE(fn),
1400                                         &rt->fib6_src.addr, rt->fib6_src.plen,
1401                                         offsetof(struct fib6_info, fib6_src),
1402                                         allow_create, replace_required, extack);
1403
1404                         if (IS_ERR(sn)) {
1405                                 err = PTR_ERR(sn);
1406                                 goto failure;
1407                         }
1408                 }
1409
1410                 if (!rcu_access_pointer(fn->leaf)) {
1411                         if (fn->fn_flags & RTN_TL_ROOT) {
1412                                 /* put back null_entry for root node */
1413                                 rcu_assign_pointer(fn->leaf,
1414                                             info->nl_net->ipv6.fib6_null_entry);
1415                         } else {
1416                                 fib6_info_hold(rt);
1417                                 rcu_assign_pointer(fn->leaf, rt);
1418                         }
1419                 }
1420                 fn = sn;
1421         }
1422 #endif
1423
1424         err = fib6_add_rt2node(fn, rt, info, extack);
1425         if (!err) {
1426                 if (rt->nh)
1427                         list_add(&rt->nh_list, &rt->nh->f6i_list);
1428                 __fib6_update_sernum_upto_root(rt, sernum);
1429                 fib6_start_gc(info->nl_net, rt);
1430         }
1431
1432 out:
1433         if (err) {
1434 #ifdef CONFIG_IPV6_SUBTREES
1435                 /*
1436                  * If fib6_add_1 has cleared the old leaf pointer in the
1437                  * super-tree leaf node we have to find a new one for it.
1438                  */
1439                 if (pn != fn) {
1440                         struct fib6_info *pn_leaf =
1441                                 rcu_dereference_protected(pn->leaf,
1442                                     lockdep_is_held(&table->tb6_lock));
1443                         if (pn_leaf == rt) {
1444                                 pn_leaf = NULL;
1445                                 RCU_INIT_POINTER(pn->leaf, NULL);
1446                                 fib6_info_release(rt);
1447                         }
1448                         if (!pn_leaf && !(pn->fn_flags & RTN_RTINFO)) {
1449                                 pn_leaf = fib6_find_prefix(info->nl_net, table,
1450                                                            pn);
1451 #if RT6_DEBUG >= 2
1452                                 if (!pn_leaf) {
1453                                         WARN_ON(!pn_leaf);
1454                                         pn_leaf =
1455                                             info->nl_net->ipv6.fib6_null_entry;
1456                                 }
1457 #endif
1458                                 fib6_info_hold(pn_leaf);
1459                                 rcu_assign_pointer(pn->leaf, pn_leaf);
1460                         }
1461                 }
1462 #endif
1463                 goto failure;
1464         } else if (fib6_requires_src(rt)) {
1465                 fib6_routes_require_src_inc(info->nl_net);
1466         }
1467         return err;
1468
1469 failure:
1470         /* fn->leaf could be NULL and fib6_repair_tree() needs to be called if:
1471          * 1. fn is an intermediate node and we failed to add the new
1472          * route to it in both subtree creation failure and fib6_add_rt2node()
1473          * failure case.
1474          * 2. fn is the root node in the table and we fail to add the first
1475          * default route to it.
1476          */
1477         if (fn &&
1478             (!(fn->fn_flags & (RTN_RTINFO|RTN_ROOT)) ||
1479              (fn->fn_flags & RTN_TL_ROOT &&
1480               !rcu_access_pointer(fn->leaf))))
1481                 fib6_repair_tree(info->nl_net, table, fn);
1482         return err;
1483 }
1484
1485 /*
1486  *      Routing tree lookup
1487  *
1488  */
1489
1490 struct lookup_args {
1491         int                     offset;         /* key offset on fib6_info */
1492         const struct in6_addr   *addr;          /* search key                   */
1493 };
1494
1495 static struct fib6_node *fib6_node_lookup_1(struct fib6_node *root,
1496                                             struct lookup_args *args)
1497 {
1498         struct fib6_node *fn;
1499         __be32 dir;
1500
1501         if (unlikely(args->offset == 0))
1502                 return NULL;
1503
1504         /*
1505          *      Descend on a tree
1506          */
1507
1508         fn = root;
1509
1510         for (;;) {
1511                 struct fib6_node *next;
1512
1513                 dir = addr_bit_set(args->addr, fn->fn_bit);
1514
1515                 next = dir ? rcu_dereference(fn->right) :
1516                              rcu_dereference(fn->left);
1517
1518                 if (next) {
1519                         fn = next;
1520                         continue;
1521                 }
1522                 break;
1523         }
1524
1525         while (fn) {
1526                 struct fib6_node *subtree = FIB6_SUBTREE(fn);
1527
1528                 if (subtree || fn->fn_flags & RTN_RTINFO) {
1529                         struct fib6_info *leaf = rcu_dereference(fn->leaf);
1530                         struct rt6key *key;
1531
1532                         if (!leaf)
1533                                 goto backtrack;
1534
1535                         key = (struct rt6key *) ((u8 *)leaf + args->offset);
1536
1537                         if (ipv6_prefix_equal(&key->addr, args->addr, key->plen)) {
1538 #ifdef CONFIG_IPV6_SUBTREES
1539                                 if (subtree) {
1540                                         struct fib6_node *sfn;
1541                                         sfn = fib6_node_lookup_1(subtree,
1542                                                                  args + 1);
1543                                         if (!sfn)
1544                                                 goto backtrack;
1545                                         fn = sfn;
1546                                 }
1547 #endif
1548                                 if (fn->fn_flags & RTN_RTINFO)
1549                                         return fn;
1550                         }
1551                 }
1552 backtrack:
1553                 if (fn->fn_flags & RTN_ROOT)
1554                         break;
1555
1556                 fn = rcu_dereference(fn->parent);
1557         }
1558
1559         return NULL;
1560 }
1561
1562 /* called with rcu_read_lock() held
1563  */
1564 struct fib6_node *fib6_node_lookup(struct fib6_node *root,
1565                                    const struct in6_addr *daddr,
1566                                    const struct in6_addr *saddr)
1567 {
1568         struct fib6_node *fn;
1569         struct lookup_args args[] = {
1570                 {
1571                         .offset = offsetof(struct fib6_info, fib6_dst),
1572                         .addr = daddr,
1573                 },
1574 #ifdef CONFIG_IPV6_SUBTREES
1575                 {
1576                         .offset = offsetof(struct fib6_info, fib6_src),
1577                         .addr = saddr,
1578                 },
1579 #endif
1580                 {
1581                         .offset = 0,    /* sentinel */
1582                 }
1583         };
1584
1585         fn = fib6_node_lookup_1(root, daddr ? args : args + 1);
1586         if (!fn || fn->fn_flags & RTN_TL_ROOT)
1587                 fn = root;
1588
1589         return fn;
1590 }
1591
1592 /*
1593  *      Get node with specified destination prefix (and source prefix,
1594  *      if subtrees are used)
1595  *      exact_match == true means we try to find fn with exact match of
1596  *      the passed in prefix addr
1597  *      exact_match == false means we try to find fn with longest prefix
1598  *      match of the passed in prefix addr. This is useful for finding fn
1599  *      for cached route as it will be stored in the exception table under
1600  *      the node with longest prefix length.
1601  */
1602
1603
1604 static struct fib6_node *fib6_locate_1(struct fib6_node *root,
1605                                        const struct in6_addr *addr,
1606                                        int plen, int offset,
1607                                        bool exact_match)
1608 {
1609         struct fib6_node *fn, *prev = NULL;
1610
1611         for (fn = root; fn ; ) {
1612                 struct fib6_info *leaf = rcu_dereference(fn->leaf);
1613                 struct rt6key *key;
1614
1615                 /* This node is being deleted */
1616                 if (!leaf) {
1617                         if (plen <= fn->fn_bit)
1618                                 goto out;
1619                         else
1620                                 goto next;
1621                 }
1622
1623                 key = (struct rt6key *)((u8 *)leaf + offset);
1624
1625                 /*
1626                  *      Prefix match
1627                  */
1628                 if (plen < fn->fn_bit ||
1629                     !ipv6_prefix_equal(&key->addr, addr, fn->fn_bit))
1630                         goto out;
1631
1632                 if (plen == fn->fn_bit)
1633                         return fn;
1634
1635                 if (fn->fn_flags & RTN_RTINFO)
1636                         prev = fn;
1637
1638 next:
1639                 /*
1640                  *      We have more bits to go
1641                  */
1642                 if (addr_bit_set(addr, fn->fn_bit))
1643                         fn = rcu_dereference(fn->right);
1644                 else
1645                         fn = rcu_dereference(fn->left);
1646         }
1647 out:
1648         if (exact_match)
1649                 return NULL;
1650         else
1651                 return prev;
1652 }
1653
1654 struct fib6_node *fib6_locate(struct fib6_node *root,
1655                               const struct in6_addr *daddr, int dst_len,
1656                               const struct in6_addr *saddr, int src_len,
1657                               bool exact_match)
1658 {
1659         struct fib6_node *fn;
1660
1661         fn = fib6_locate_1(root, daddr, dst_len,
1662                            offsetof(struct fib6_info, fib6_dst),
1663                            exact_match);
1664
1665 #ifdef CONFIG_IPV6_SUBTREES
1666         if (src_len) {
1667                 WARN_ON(saddr == NULL);
1668                 if (fn) {
1669                         struct fib6_node *subtree = FIB6_SUBTREE(fn);
1670
1671                         if (subtree) {
1672                                 fn = fib6_locate_1(subtree, saddr, src_len,
1673                                            offsetof(struct fib6_info, fib6_src),
1674                                            exact_match);
1675                         }
1676                 }
1677         }
1678 #endif
1679
1680         if (fn && fn->fn_flags & RTN_RTINFO)
1681                 return fn;
1682
1683         return NULL;
1684 }
1685
1686
1687 /*
1688  *      Deletion
1689  *
1690  */
1691
1692 static struct fib6_info *fib6_find_prefix(struct net *net,
1693                                          struct fib6_table *table,
1694                                          struct fib6_node *fn)
1695 {
1696         struct fib6_node *child_left, *child_right;
1697
1698         if (fn->fn_flags & RTN_ROOT)
1699                 return net->ipv6.fib6_null_entry;
1700
1701         while (fn) {
1702                 child_left = rcu_dereference_protected(fn->left,
1703                                     lockdep_is_held(&table->tb6_lock));
1704                 child_right = rcu_dereference_protected(fn->right,
1705                                     lockdep_is_held(&table->tb6_lock));
1706                 if (child_left)
1707                         return rcu_dereference_protected(child_left->leaf,
1708                                         lockdep_is_held(&table->tb6_lock));
1709                 if (child_right)
1710                         return rcu_dereference_protected(child_right->leaf,
1711                                         lockdep_is_held(&table->tb6_lock));
1712
1713                 fn = FIB6_SUBTREE(fn);
1714         }
1715         return NULL;
1716 }
1717
1718 /*
1719  *      Called to trim the tree of intermediate nodes when possible. "fn"
1720  *      is the node we want to try and remove.
1721  *      Need to own table->tb6_lock
1722  */
1723
1724 static struct fib6_node *fib6_repair_tree(struct net *net,
1725                                           struct fib6_table *table,
1726                                           struct fib6_node *fn)
1727 {
1728         int children;
1729         int nstate;
1730         struct fib6_node *child;
1731         struct fib6_walker *w;
1732         int iter = 0;
1733
1734         /* Set fn->leaf to null_entry for root node. */
1735         if (fn->fn_flags & RTN_TL_ROOT) {
1736                 rcu_assign_pointer(fn->leaf, net->ipv6.fib6_null_entry);
1737                 return fn;
1738         }
1739
1740         for (;;) {
1741                 struct fib6_node *fn_r = rcu_dereference_protected(fn->right,
1742                                             lockdep_is_held(&table->tb6_lock));
1743                 struct fib6_node *fn_l = rcu_dereference_protected(fn->left,
1744                                             lockdep_is_held(&table->tb6_lock));
1745                 struct fib6_node *pn = rcu_dereference_protected(fn->parent,
1746                                             lockdep_is_held(&table->tb6_lock));
1747                 struct fib6_node *pn_r = rcu_dereference_protected(pn->right,
1748                                             lockdep_is_held(&table->tb6_lock));
1749                 struct fib6_node *pn_l = rcu_dereference_protected(pn->left,
1750                                             lockdep_is_held(&table->tb6_lock));
1751                 struct fib6_info *fn_leaf = rcu_dereference_protected(fn->leaf,
1752                                             lockdep_is_held(&table->tb6_lock));
1753                 struct fib6_info *pn_leaf = rcu_dereference_protected(pn->leaf,
1754                                             lockdep_is_held(&table->tb6_lock));
1755                 struct fib6_info *new_fn_leaf;
1756
1757                 RT6_TRACE("fixing tree: plen=%d iter=%d\n", fn->fn_bit, iter);
1758                 iter++;
1759
1760                 WARN_ON(fn->fn_flags & RTN_RTINFO);
1761                 WARN_ON(fn->fn_flags & RTN_TL_ROOT);
1762                 WARN_ON(fn_leaf);
1763
1764                 children = 0;
1765                 child = NULL;
1766                 if (fn_r)
1767                         child = fn_r, children |= 1;
1768                 if (fn_l)
1769                         child = fn_l, children |= 2;
1770
1771                 if (children == 3 || FIB6_SUBTREE(fn)
1772 #ifdef CONFIG_IPV6_SUBTREES
1773                     /* Subtree root (i.e. fn) may have one child */
1774                     || (children && fn->fn_flags & RTN_ROOT)
1775 #endif
1776                     ) {
1777                         new_fn_leaf = fib6_find_prefix(net, table, fn);
1778 #if RT6_DEBUG >= 2
1779                         if (!new_fn_leaf) {
1780                                 WARN_ON(!new_fn_leaf);
1781                                 new_fn_leaf = net->ipv6.fib6_null_entry;
1782                         }
1783 #endif
1784                         fib6_info_hold(new_fn_leaf);
1785                         rcu_assign_pointer(fn->leaf, new_fn_leaf);
1786                         return pn;
1787                 }
1788
1789 #ifdef CONFIG_IPV6_SUBTREES
1790                 if (FIB6_SUBTREE(pn) == fn) {
1791                         WARN_ON(!(fn->fn_flags & RTN_ROOT));
1792                         RCU_INIT_POINTER(pn->subtree, NULL);
1793                         nstate = FWS_L;
1794                 } else {
1795                         WARN_ON(fn->fn_flags & RTN_ROOT);
1796 #endif
1797                         if (pn_r == fn)
1798                                 rcu_assign_pointer(pn->right, child);
1799                         else if (pn_l == fn)
1800                                 rcu_assign_pointer(pn->left, child);
1801 #if RT6_DEBUG >= 2
1802                         else
1803                                 WARN_ON(1);
1804 #endif
1805                         if (child)
1806                                 rcu_assign_pointer(child->parent, pn);
1807                         nstate = FWS_R;
1808 #ifdef CONFIG_IPV6_SUBTREES
1809                 }
1810 #endif
1811
1812                 read_lock(&net->ipv6.fib6_walker_lock);
1813                 FOR_WALKERS(net, w) {
1814                         if (!child) {
1815                                 if (w->node == fn) {
1816                                         RT6_TRACE("W %p adjusted by delnode 1, s=%d/%d\n", w, w->state, nstate);
1817                                         w->node = pn;
1818                                         w->state = nstate;
1819                                 }
1820                         } else {
1821                                 if (w->node == fn) {
1822                                         w->node = child;
1823                                         if (children&2) {
1824                                                 RT6_TRACE("W %p adjusted by delnode 2, s=%d\n", w, w->state);
1825                                                 w->state = w->state >= FWS_R ? FWS_U : FWS_INIT;
1826                                         } else {
1827                                                 RT6_TRACE("W %p adjusted by delnode 2, s=%d\n", w, w->state);
1828                                                 w->state = w->state >= FWS_C ? FWS_U : FWS_INIT;
1829                                         }
1830                                 }
1831                         }
1832                 }
1833                 read_unlock(&net->ipv6.fib6_walker_lock);
1834
1835                 node_free(net, fn);
1836                 if (pn->fn_flags & RTN_RTINFO || FIB6_SUBTREE(pn))
1837                         return pn;
1838
1839                 RCU_INIT_POINTER(pn->leaf, NULL);
1840                 fib6_info_release(pn_leaf);
1841                 fn = pn;
1842         }
1843 }
1844
1845 static void fib6_del_route(struct fib6_table *table, struct fib6_node *fn,
1846                            struct fib6_info __rcu **rtp, struct nl_info *info)
1847 {
1848         struct fib6_walker *w;
1849         struct fib6_info *rt = rcu_dereference_protected(*rtp,
1850                                     lockdep_is_held(&table->tb6_lock));
1851         struct net *net = info->nl_net;
1852
1853         RT6_TRACE("fib6_del_route\n");
1854
1855         /* Unlink it */
1856         *rtp = rt->fib6_next;
1857         rt->fib6_node = NULL;
1858         net->ipv6.rt6_stats->fib_rt_entries--;
1859         net->ipv6.rt6_stats->fib_discarded_routes++;
1860
1861         /* Flush all cached dst in exception table */
1862         rt6_flush_exceptions(rt);
1863
1864         /* Reset round-robin state, if necessary */
1865         if (rcu_access_pointer(fn->rr_ptr) == rt)
1866                 fn->rr_ptr = NULL;
1867
1868         /* Remove this entry from other siblings */
1869         if (rt->fib6_nsiblings) {
1870                 struct fib6_info *sibling, *next_sibling;
1871
1872                 list_for_each_entry_safe(sibling, next_sibling,
1873                                          &rt->fib6_siblings, fib6_siblings)
1874                         sibling->fib6_nsiblings--;
1875                 rt->fib6_nsiblings = 0;
1876                 list_del_init(&rt->fib6_siblings);
1877                 rt6_multipath_rebalance(next_sibling);
1878         }
1879
1880         /* Adjust walkers */
1881         read_lock(&net->ipv6.fib6_walker_lock);
1882         FOR_WALKERS(net, w) {
1883                 if (w->state == FWS_C && w->leaf == rt) {
1884                         RT6_TRACE("walker %p adjusted by delroute\n", w);
1885                         w->leaf = rcu_dereference_protected(rt->fib6_next,
1886                                             lockdep_is_held(&table->tb6_lock));
1887                         if (!w->leaf)
1888                                 w->state = FWS_U;
1889                 }
1890         }
1891         read_unlock(&net->ipv6.fib6_walker_lock);
1892
1893         /* If it was last route, call fib6_repair_tree() to:
1894          * 1. For root node, put back null_entry as how the table was created.
1895          * 2. For other nodes, expunge its radix tree node.
1896          */
1897         if (!rcu_access_pointer(fn->leaf)) {
1898                 if (!(fn->fn_flags & RTN_TL_ROOT)) {
1899                         fn->fn_flags &= ~RTN_RTINFO;
1900                         net->ipv6.rt6_stats->fib_route_nodes--;
1901                 }
1902                 fn = fib6_repair_tree(net, table, fn);
1903         }
1904
1905         fib6_purge_rt(rt, fn, net);
1906
1907         if (!info->skip_notify_kernel)
1908                 call_fib6_entry_notifiers(net, FIB_EVENT_ENTRY_DEL, rt, NULL);
1909         if (!info->skip_notify)
1910                 inet6_rt_notify(RTM_DELROUTE, rt, info, 0);
1911
1912         fib6_info_release(rt);
1913 }
1914
1915 /* Need to own table->tb6_lock */
1916 int fib6_del(struct fib6_info *rt, struct nl_info *info)
1917 {
1918         struct fib6_node *fn = rcu_dereference_protected(rt->fib6_node,
1919                                     lockdep_is_held(&rt->fib6_table->tb6_lock));
1920         struct fib6_table *table = rt->fib6_table;
1921         struct net *net = info->nl_net;
1922         struct fib6_info __rcu **rtp;
1923         struct fib6_info __rcu **rtp_next;
1924
1925         if (!fn || rt == net->ipv6.fib6_null_entry)
1926                 return -ENOENT;
1927
1928         WARN_ON(!(fn->fn_flags & RTN_RTINFO));
1929
1930         /*
1931          *      Walk the leaf entries looking for ourself
1932          */
1933
1934         for (rtp = &fn->leaf; *rtp; rtp = rtp_next) {
1935                 struct fib6_info *cur = rcu_dereference_protected(*rtp,
1936                                         lockdep_is_held(&table->tb6_lock));
1937                 if (rt == cur) {
1938                         if (fib6_requires_src(cur))
1939                                 fib6_routes_require_src_dec(info->nl_net);
1940                         fib6_del_route(table, fn, rtp, info);
1941                         return 0;
1942                 }
1943                 rtp_next = &cur->fib6_next;
1944         }
1945         return -ENOENT;
1946 }
1947
1948 /*
1949  *      Tree traversal function.
1950  *
1951  *      Certainly, it is not interrupt safe.
1952  *      However, it is internally reenterable wrt itself and fib6_add/fib6_del.
1953  *      It means, that we can modify tree during walking
1954  *      and use this function for garbage collection, clone pruning,
1955  *      cleaning tree when a device goes down etc. etc.
1956  *
1957  *      It guarantees that every node will be traversed,
1958  *      and that it will be traversed only once.
1959  *
1960  *      Callback function w->func may return:
1961  *      0 -> continue walking.
1962  *      positive value -> walking is suspended (used by tree dumps,
1963  *      and probably by gc, if it will be split to several slices)
1964  *      negative value -> terminate walking.
1965  *
1966  *      The function itself returns:
1967  *      0   -> walk is complete.
1968  *      >0  -> walk is incomplete (i.e. suspended)
1969  *      <0  -> walk is terminated by an error.
1970  *
1971  *      This function is called with tb6_lock held.
1972  */
1973
1974 static int fib6_walk_continue(struct fib6_walker *w)
1975 {
1976         struct fib6_node *fn, *pn, *left, *right;
1977
1978         /* w->root should always be table->tb6_root */
1979         WARN_ON_ONCE(!(w->root->fn_flags & RTN_TL_ROOT));
1980
1981         for (;;) {
1982                 fn = w->node;
1983                 if (!fn)
1984                         return 0;
1985
1986                 switch (w->state) {
1987 #ifdef CONFIG_IPV6_SUBTREES
1988                 case FWS_S:
1989                         if (FIB6_SUBTREE(fn)) {
1990                                 w->node = FIB6_SUBTREE(fn);
1991                                 continue;
1992                         }
1993                         w->state = FWS_L;
1994 #endif
1995                         /* fall through */
1996                 case FWS_L:
1997                         left = rcu_dereference_protected(fn->left, 1);
1998                         if (left) {
1999                                 w->node = left;
2000                                 w->state = FWS_INIT;
2001                                 continue;
2002                         }
2003                         w->state = FWS_R;
2004                         /* fall through */
2005                 case FWS_R:
2006                         right = rcu_dereference_protected(fn->right, 1);
2007                         if (right) {
2008                                 w->node = right;
2009                                 w->state = FWS_INIT;
2010                                 continue;
2011                         }
2012                         w->state = FWS_C;
2013                         w->leaf = rcu_dereference_protected(fn->leaf, 1);
2014                         /* fall through */
2015                 case FWS_C:
2016                         if (w->leaf && fn->fn_flags & RTN_RTINFO) {
2017                                 int err;
2018
2019                                 if (w->skip) {
2020                                         w->skip--;
2021                                         goto skip;
2022                                 }
2023
2024                                 err = w->func(w);
2025                                 if (err)
2026                                         return err;
2027
2028                                 w->count++;
2029                                 continue;
2030                         }
2031 skip:
2032                         w->state = FWS_U;
2033                         /* fall through */
2034                 case FWS_U:
2035                         if (fn == w->root)
2036                                 return 0;
2037                         pn = rcu_dereference_protected(fn->parent, 1);
2038                         left = rcu_dereference_protected(pn->left, 1);
2039                         right = rcu_dereference_protected(pn->right, 1);
2040                         w->node = pn;
2041 #ifdef CONFIG_IPV6_SUBTREES
2042                         if (FIB6_SUBTREE(pn) == fn) {
2043                                 WARN_ON(!(fn->fn_flags & RTN_ROOT));
2044                                 w->state = FWS_L;
2045                                 continue;
2046                         }
2047 #endif
2048                         if (left == fn) {
2049                                 w->state = FWS_R;
2050                                 continue;
2051                         }
2052                         if (right == fn) {
2053                                 w->state = FWS_C;
2054                                 w->leaf = rcu_dereference_protected(w->node->leaf, 1);
2055                                 continue;
2056                         }
2057 #if RT6_DEBUG >= 2
2058                         WARN_ON(1);
2059 #endif
2060                 }
2061         }
2062 }
2063
2064 static int fib6_walk(struct net *net, struct fib6_walker *w)
2065 {
2066         int res;
2067
2068         w->state = FWS_INIT;
2069         w->node = w->root;
2070
2071         fib6_walker_link(net, w);
2072         res = fib6_walk_continue(w);
2073         if (res <= 0)
2074                 fib6_walker_unlink(net, w);
2075         return res;
2076 }
2077
2078 static int fib6_clean_node(struct fib6_walker *w)
2079 {
2080         int res;
2081         struct fib6_info *rt;
2082         struct fib6_cleaner *c = container_of(w, struct fib6_cleaner, w);
2083         struct nl_info info = {
2084                 .nl_net = c->net,
2085                 .skip_notify = c->skip_notify,
2086         };
2087
2088         if (c->sernum != FIB6_NO_SERNUM_CHANGE &&
2089             w->node->fn_sernum != c->sernum)
2090                 w->node->fn_sernum = c->sernum;
2091
2092         if (!c->func) {
2093                 WARN_ON_ONCE(c->sernum == FIB6_NO_SERNUM_CHANGE);
2094                 w->leaf = NULL;
2095                 return 0;
2096         }
2097
2098         for_each_fib6_walker_rt(w) {
2099                 res = c->func(rt, c->arg);
2100                 if (res == -1) {
2101                         w->leaf = rt;
2102                         res = fib6_del(rt, &info);
2103                         if (res) {
2104 #if RT6_DEBUG >= 2
2105                                 pr_debug("%s: del failed: rt=%p@%p err=%d\n",
2106                                          __func__, rt,
2107                                          rcu_access_pointer(rt->fib6_node),
2108                                          res);
2109 #endif
2110                                 continue;
2111                         }
2112                         return 0;
2113                 } else if (res == -2) {
2114                         if (WARN_ON(!rt->fib6_nsiblings))
2115                                 continue;
2116                         rt = list_last_entry(&rt->fib6_siblings,
2117                                              struct fib6_info, fib6_siblings);
2118                         continue;
2119                 }
2120                 WARN_ON(res != 0);
2121         }
2122         w->leaf = rt;
2123         return 0;
2124 }
2125
2126 /*
2127  *      Convenient frontend to tree walker.
2128  *
2129  *      func is called on each route.
2130  *              It may return -2 -> skip multipath route.
2131  *                            -1 -> delete this route.
2132  *                            0  -> continue walking
2133  */
2134
2135 static void fib6_clean_tree(struct net *net, struct fib6_node *root,
2136                             int (*func)(struct fib6_info *, void *arg),
2137                             int sernum, void *arg, bool skip_notify)
2138 {
2139         struct fib6_cleaner c;
2140
2141         c.w.root = root;
2142         c.w.func = fib6_clean_node;
2143         c.w.count = 0;
2144         c.w.skip = 0;
2145         c.w.skip_in_node = 0;
2146         c.func = func;
2147         c.sernum = sernum;
2148         c.arg = arg;
2149         c.net = net;
2150         c.skip_notify = skip_notify;
2151
2152         fib6_walk(net, &c.w);
2153 }
2154
2155 static void __fib6_clean_all(struct net *net,
2156                              int (*func)(struct fib6_info *, void *),
2157                              int sernum, void *arg, bool skip_notify)
2158 {
2159         struct fib6_table *table;
2160         struct hlist_head *head;
2161         unsigned int h;
2162
2163         rcu_read_lock();
2164         for (h = 0; h < FIB6_TABLE_HASHSZ; h++) {
2165                 head = &net->ipv6.fib_table_hash[h];
2166                 hlist_for_each_entry_rcu(table, head, tb6_hlist) {
2167                         spin_lock_bh(&table->tb6_lock);
2168                         fib6_clean_tree(net, &table->tb6_root,
2169                                         func, sernum, arg, skip_notify);
2170                         spin_unlock_bh(&table->tb6_lock);
2171                 }
2172         }
2173         rcu_read_unlock();
2174 }
2175
2176 void fib6_clean_all(struct net *net, int (*func)(struct fib6_info *, void *),
2177                     void *arg)
2178 {
2179         __fib6_clean_all(net, func, FIB6_NO_SERNUM_CHANGE, arg, false);
2180 }
2181
2182 void fib6_clean_all_skip_notify(struct net *net,
2183                                 int (*func)(struct fib6_info *, void *),
2184                                 void *arg)
2185 {
2186         __fib6_clean_all(net, func, FIB6_NO_SERNUM_CHANGE, arg, true);
2187 }
2188
2189 static void fib6_flush_trees(struct net *net)
2190 {
2191         int new_sernum = fib6_new_sernum(net);
2192
2193         __fib6_clean_all(net, NULL, new_sernum, NULL, false);
2194 }
2195
2196 /*
2197  *      Garbage collection
2198  */
2199
2200 static int fib6_age(struct fib6_info *rt, void *arg)
2201 {
2202         struct fib6_gc_args *gc_args = arg;
2203         unsigned long now = jiffies;
2204
2205         /*
2206          *      check addrconf expiration here.
2207          *      Routes are expired even if they are in use.
2208          */
2209
2210         if (rt->fib6_flags & RTF_EXPIRES && rt->expires) {
2211                 if (time_after(now, rt->expires)) {
2212                         RT6_TRACE("expiring %p\n", rt);
2213                         return -1;
2214                 }
2215                 gc_args->more++;
2216         }
2217
2218         /*      Also age clones in the exception table.
2219          *      Note, that clones are aged out
2220          *      only if they are not in use now.
2221          */
2222         rt6_age_exceptions(rt, gc_args, now);
2223
2224         return 0;
2225 }
2226
2227 void fib6_run_gc(unsigned long expires, struct net *net, bool force)
2228 {
2229         struct fib6_gc_args gc_args;
2230         unsigned long now;
2231
2232         if (force) {
2233                 spin_lock_bh(&net->ipv6.fib6_gc_lock);
2234         } else if (!spin_trylock_bh(&net->ipv6.fib6_gc_lock)) {
2235                 mod_timer(&net->ipv6.ip6_fib_timer, jiffies + HZ);
2236                 return;
2237         }
2238         gc_args.timeout = expires ? (int)expires :
2239                           net->ipv6.sysctl.ip6_rt_gc_interval;
2240         gc_args.more = 0;
2241
2242         fib6_clean_all(net, fib6_age, &gc_args);
2243         now = jiffies;
2244         net->ipv6.ip6_rt_last_gc = now;
2245
2246         if (gc_args.more)
2247                 mod_timer(&net->ipv6.ip6_fib_timer,
2248                           round_jiffies(now
2249                                         + net->ipv6.sysctl.ip6_rt_gc_interval));
2250         else
2251                 del_timer(&net->ipv6.ip6_fib_timer);
2252         spin_unlock_bh(&net->ipv6.fib6_gc_lock);
2253 }
2254
2255 static void fib6_gc_timer_cb(struct timer_list *t)
2256 {
2257         struct net *arg = from_timer(arg, t, ipv6.ip6_fib_timer);
2258
2259         fib6_run_gc(0, arg, true);
2260 }
2261
2262 static int __net_init fib6_net_init(struct net *net)
2263 {
2264         size_t size = sizeof(struct hlist_head) * FIB6_TABLE_HASHSZ;
2265         int err;
2266
2267         err = fib6_notifier_init(net);
2268         if (err)
2269                 return err;
2270
2271         spin_lock_init(&net->ipv6.fib6_gc_lock);
2272         rwlock_init(&net->ipv6.fib6_walker_lock);
2273         INIT_LIST_HEAD(&net->ipv6.fib6_walkers);
2274         timer_setup(&net->ipv6.ip6_fib_timer, fib6_gc_timer_cb, 0);
2275
2276         net->ipv6.rt6_stats = kzalloc(sizeof(*net->ipv6.rt6_stats), GFP_KERNEL);
2277         if (!net->ipv6.rt6_stats)
2278                 goto out_timer;
2279
2280         /* Avoid false sharing : Use at least a full cache line */
2281         size = max_t(size_t, size, L1_CACHE_BYTES);
2282
2283         net->ipv6.fib_table_hash = kzalloc(size, GFP_KERNEL);
2284         if (!net->ipv6.fib_table_hash)
2285                 goto out_rt6_stats;
2286
2287         net->ipv6.fib6_main_tbl = kzalloc(sizeof(*net->ipv6.fib6_main_tbl),
2288                                           GFP_KERNEL);
2289         if (!net->ipv6.fib6_main_tbl)
2290                 goto out_fib_table_hash;
2291
2292         net->ipv6.fib6_main_tbl->tb6_id = RT6_TABLE_MAIN;
2293         rcu_assign_pointer(net->ipv6.fib6_main_tbl->tb6_root.leaf,
2294                            net->ipv6.fib6_null_entry);
2295         net->ipv6.fib6_main_tbl->tb6_root.fn_flags =
2296                 RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
2297         inet_peer_base_init(&net->ipv6.fib6_main_tbl->tb6_peers);
2298
2299 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
2300         net->ipv6.fib6_local_tbl = kzalloc(sizeof(*net->ipv6.fib6_local_tbl),
2301                                            GFP_KERNEL);
2302         if (!net->ipv6.fib6_local_tbl)
2303                 goto out_fib6_main_tbl;
2304         net->ipv6.fib6_local_tbl->tb6_id = RT6_TABLE_LOCAL;
2305         rcu_assign_pointer(net->ipv6.fib6_local_tbl->tb6_root.leaf,
2306                            net->ipv6.fib6_null_entry);
2307         net->ipv6.fib6_local_tbl->tb6_root.fn_flags =
2308                 RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
2309         inet_peer_base_init(&net->ipv6.fib6_local_tbl->tb6_peers);
2310 #endif
2311         fib6_tables_init(net);
2312
2313         return 0;
2314
2315 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
2316 out_fib6_main_tbl:
2317         kfree(net->ipv6.fib6_main_tbl);
2318 #endif
2319 out_fib_table_hash:
2320         kfree(net->ipv6.fib_table_hash);
2321 out_rt6_stats:
2322         kfree(net->ipv6.rt6_stats);
2323 out_timer:
2324         fib6_notifier_exit(net);
2325         return -ENOMEM;
2326 }
2327
2328 static void fib6_net_exit(struct net *net)
2329 {
2330         unsigned int i;
2331
2332         del_timer_sync(&net->ipv6.ip6_fib_timer);
2333
2334         for (i = 0; i < FIB6_TABLE_HASHSZ; i++) {
2335                 struct hlist_head *head = &net->ipv6.fib_table_hash[i];
2336                 struct hlist_node *tmp;
2337                 struct fib6_table *tb;
2338
2339                 hlist_for_each_entry_safe(tb, tmp, head, tb6_hlist) {
2340                         hlist_del(&tb->tb6_hlist);
2341                         fib6_free_table(tb);
2342                 }
2343         }
2344
2345         kfree(net->ipv6.fib_table_hash);
2346         kfree(net->ipv6.rt6_stats);
2347         fib6_notifier_exit(net);
2348 }
2349
2350 static struct pernet_operations fib6_net_ops = {
2351         .init = fib6_net_init,
2352         .exit = fib6_net_exit,
2353 };
2354
2355 int __init fib6_init(void)
2356 {
2357         int ret = -ENOMEM;
2358
2359         fib6_node_kmem = kmem_cache_create("fib6_nodes",
2360                                            sizeof(struct fib6_node),
2361                                            0, SLAB_HWCACHE_ALIGN,
2362                                            NULL);
2363         if (!fib6_node_kmem)
2364                 goto out;
2365
2366         ret = register_pernet_subsys(&fib6_net_ops);
2367         if (ret)
2368                 goto out_kmem_cache_create;
2369
2370         ret = rtnl_register_module(THIS_MODULE, PF_INET6, RTM_GETROUTE, NULL,
2371                                    inet6_dump_fib, 0);
2372         if (ret)
2373                 goto out_unregister_subsys;
2374
2375         __fib6_flush_trees = fib6_flush_trees;
2376 out:
2377         return ret;
2378
2379 out_unregister_subsys:
2380         unregister_pernet_subsys(&fib6_net_ops);
2381 out_kmem_cache_create:
2382         kmem_cache_destroy(fib6_node_kmem);
2383         goto out;
2384 }
2385
2386 void fib6_gc_cleanup(void)
2387 {
2388         unregister_pernet_subsys(&fib6_net_ops);
2389         kmem_cache_destroy(fib6_node_kmem);
2390 }
2391
2392 #ifdef CONFIG_PROC_FS
2393 static int ipv6_route_seq_show(struct seq_file *seq, void *v)
2394 {
2395         struct fib6_info *rt = v;
2396         struct ipv6_route_iter *iter = seq->private;
2397         struct fib6_nh *fib6_nh = rt->fib6_nh;
2398         unsigned int flags = rt->fib6_flags;
2399         const struct net_device *dev;
2400
2401         if (rt->nh)
2402                 fib6_nh = nexthop_fib6_nh(rt->nh);
2403
2404         seq_printf(seq, "%pi6 %02x ", &rt->fib6_dst.addr, rt->fib6_dst.plen);
2405
2406 #ifdef CONFIG_IPV6_SUBTREES
2407         seq_printf(seq, "%pi6 %02x ", &rt->fib6_src.addr, rt->fib6_src.plen);
2408 #else
2409         seq_puts(seq, "00000000000000000000000000000000 00 ");
2410 #endif
2411         if (fib6_nh->fib_nh_gw_family) {
2412                 flags |= RTF_GATEWAY;
2413                 seq_printf(seq, "%pi6", &fib6_nh->fib_nh_gw6);
2414         } else {
2415                 seq_puts(seq, "00000000000000000000000000000000");
2416         }
2417
2418         dev = fib6_nh->fib_nh_dev;
2419         seq_printf(seq, " %08x %08x %08x %08x %8s\n",
2420                    rt->fib6_metric, refcount_read(&rt->fib6_ref), 0,
2421                    flags, dev ? dev->name : "");
2422         iter->w.leaf = NULL;
2423         return 0;
2424 }
2425
2426 static int ipv6_route_yield(struct fib6_walker *w)
2427 {
2428         struct ipv6_route_iter *iter = w->args;
2429
2430         if (!iter->skip)
2431                 return 1;
2432
2433         do {
2434                 iter->w.leaf = rcu_dereference_protected(
2435                                 iter->w.leaf->fib6_next,
2436                                 lockdep_is_held(&iter->tbl->tb6_lock));
2437                 iter->skip--;
2438                 if (!iter->skip && iter->w.leaf)
2439                         return 1;
2440         } while (iter->w.leaf);
2441
2442         return 0;
2443 }
2444
2445 static void ipv6_route_seq_setup_walk(struct ipv6_route_iter *iter,
2446                                       struct net *net)
2447 {
2448         memset(&iter->w, 0, sizeof(iter->w));
2449         iter->w.func = ipv6_route_yield;
2450         iter->w.root = &iter->tbl->tb6_root;
2451         iter->w.state = FWS_INIT;
2452         iter->w.node = iter->w.root;
2453         iter->w.args = iter;
2454         iter->sernum = iter->w.root->fn_sernum;
2455         INIT_LIST_HEAD(&iter->w.lh);
2456         fib6_walker_link(net, &iter->w);
2457 }
2458
2459 static struct fib6_table *ipv6_route_seq_next_table(struct fib6_table *tbl,
2460                                                     struct net *net)
2461 {
2462         unsigned int h;
2463         struct hlist_node *node;
2464
2465         if (tbl) {
2466                 h = (tbl->tb6_id & (FIB6_TABLE_HASHSZ - 1)) + 1;
2467                 node = rcu_dereference_bh(hlist_next_rcu(&tbl->tb6_hlist));
2468         } else {
2469                 h = 0;
2470                 node = NULL;
2471         }
2472
2473         while (!node && h < FIB6_TABLE_HASHSZ) {
2474                 node = rcu_dereference_bh(
2475                         hlist_first_rcu(&net->ipv6.fib_table_hash[h++]));
2476         }
2477         return hlist_entry_safe(node, struct fib6_table, tb6_hlist);
2478 }
2479
2480 static void ipv6_route_check_sernum(struct ipv6_route_iter *iter)
2481 {
2482         if (iter->sernum != iter->w.root->fn_sernum) {
2483                 iter->sernum = iter->w.root->fn_sernum;
2484                 iter->w.state = FWS_INIT;
2485                 iter->w.node = iter->w.root;
2486                 WARN_ON(iter->w.skip);
2487                 iter->w.skip = iter->w.count;
2488         }
2489 }
2490
2491 static void *ipv6_route_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2492 {
2493         int r;
2494         struct fib6_info *n;
2495         struct net *net = seq_file_net(seq);
2496         struct ipv6_route_iter *iter = seq->private;
2497
2498         if (!v)
2499                 goto iter_table;
2500
2501         n = rcu_dereference_bh(((struct fib6_info *)v)->fib6_next);
2502         if (n) {
2503                 ++*pos;
2504                 return n;
2505         }
2506
2507 iter_table:
2508         ipv6_route_check_sernum(iter);
2509         spin_lock_bh(&iter->tbl->tb6_lock);
2510         r = fib6_walk_continue(&iter->w);
2511         spin_unlock_bh(&iter->tbl->tb6_lock);
2512         if (r > 0) {
2513                 if (v)
2514                         ++*pos;
2515                 return iter->w.leaf;
2516         } else if (r < 0) {
2517                 fib6_walker_unlink(net, &iter->w);
2518                 return NULL;
2519         }
2520         fib6_walker_unlink(net, &iter->w);
2521
2522         iter->tbl = ipv6_route_seq_next_table(iter->tbl, net);
2523         if (!iter->tbl)
2524                 return NULL;
2525
2526         ipv6_route_seq_setup_walk(iter, net);
2527         goto iter_table;
2528 }
2529
2530 static void *ipv6_route_seq_start(struct seq_file *seq, loff_t *pos)
2531         __acquires(RCU_BH)
2532 {
2533         struct net *net = seq_file_net(seq);
2534         struct ipv6_route_iter *iter = seq->private;
2535
2536         rcu_read_lock_bh();
2537         iter->tbl = ipv6_route_seq_next_table(NULL, net);
2538         iter->skip = *pos;
2539
2540         if (iter->tbl) {
2541                 ipv6_route_seq_setup_walk(iter, net);
2542                 return ipv6_route_seq_next(seq, NULL, pos);
2543         } else {
2544                 return NULL;
2545         }
2546 }
2547
2548 static bool ipv6_route_iter_active(struct ipv6_route_iter *iter)
2549 {
2550         struct fib6_walker *w = &iter->w;
2551         return w->node && !(w->state == FWS_U && w->node == w->root);
2552 }
2553
2554 static void ipv6_route_seq_stop(struct seq_file *seq, void *v)
2555         __releases(RCU_BH)
2556 {
2557         struct net *net = seq_file_net(seq);
2558         struct ipv6_route_iter *iter = seq->private;
2559
2560         if (ipv6_route_iter_active(iter))
2561                 fib6_walker_unlink(net, &iter->w);
2562
2563         rcu_read_unlock_bh();
2564 }
2565
2566 const struct seq_operations ipv6_route_seq_ops = {
2567         .start  = ipv6_route_seq_start,
2568         .next   = ipv6_route_seq_next,
2569         .stop   = ipv6_route_seq_stop,
2570         .show   = ipv6_route_seq_show
2571 };
2572 #endif /* CONFIG_PROC_FS */