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         }
1465         return err;
1466
1467 failure:
1468         /* fn->leaf could be NULL and fib6_repair_tree() needs to be called if:
1469          * 1. fn is an intermediate node and we failed to add the new
1470          * route to it in both subtree creation failure and fib6_add_rt2node()
1471          * failure case.
1472          * 2. fn is the root node in the table and we fail to add the first
1473          * default route to it.
1474          */
1475         if (fn &&
1476             (!(fn->fn_flags & (RTN_RTINFO|RTN_ROOT)) ||
1477              (fn->fn_flags & RTN_TL_ROOT &&
1478               !rcu_access_pointer(fn->leaf))))
1479                 fib6_repair_tree(info->nl_net, table, fn);
1480         return err;
1481 }
1482
1483 /*
1484  *      Routing tree lookup
1485  *
1486  */
1487
1488 struct lookup_args {
1489         int                     offset;         /* key offset on fib6_info */
1490         const struct in6_addr   *addr;          /* search key                   */
1491 };
1492
1493 static struct fib6_node *fib6_node_lookup_1(struct fib6_node *root,
1494                                             struct lookup_args *args)
1495 {
1496         struct fib6_node *fn;
1497         __be32 dir;
1498
1499         if (unlikely(args->offset == 0))
1500                 return NULL;
1501
1502         /*
1503          *      Descend on a tree
1504          */
1505
1506         fn = root;
1507
1508         for (;;) {
1509                 struct fib6_node *next;
1510
1511                 dir = addr_bit_set(args->addr, fn->fn_bit);
1512
1513                 next = dir ? rcu_dereference(fn->right) :
1514                              rcu_dereference(fn->left);
1515
1516                 if (next) {
1517                         fn = next;
1518                         continue;
1519                 }
1520                 break;
1521         }
1522
1523         while (fn) {
1524                 struct fib6_node *subtree = FIB6_SUBTREE(fn);
1525
1526                 if (subtree || fn->fn_flags & RTN_RTINFO) {
1527                         struct fib6_info *leaf = rcu_dereference(fn->leaf);
1528                         struct rt6key *key;
1529
1530                         if (!leaf)
1531                                 goto backtrack;
1532
1533                         key = (struct rt6key *) ((u8 *)leaf + args->offset);
1534
1535                         if (ipv6_prefix_equal(&key->addr, args->addr, key->plen)) {
1536 #ifdef CONFIG_IPV6_SUBTREES
1537                                 if (subtree) {
1538                                         struct fib6_node *sfn;
1539                                         sfn = fib6_node_lookup_1(subtree,
1540                                                                  args + 1);
1541                                         if (!sfn)
1542                                                 goto backtrack;
1543                                         fn = sfn;
1544                                 }
1545 #endif
1546                                 if (fn->fn_flags & RTN_RTINFO)
1547                                         return fn;
1548                         }
1549                 }
1550 backtrack:
1551                 if (fn->fn_flags & RTN_ROOT)
1552                         break;
1553
1554                 fn = rcu_dereference(fn->parent);
1555         }
1556
1557         return NULL;
1558 }
1559
1560 /* called with rcu_read_lock() held
1561  */
1562 struct fib6_node *fib6_node_lookup(struct fib6_node *root,
1563                                    const struct in6_addr *daddr,
1564                                    const struct in6_addr *saddr)
1565 {
1566         struct fib6_node *fn;
1567         struct lookup_args args[] = {
1568                 {
1569                         .offset = offsetof(struct fib6_info, fib6_dst),
1570                         .addr = daddr,
1571                 },
1572 #ifdef CONFIG_IPV6_SUBTREES
1573                 {
1574                         .offset = offsetof(struct fib6_info, fib6_src),
1575                         .addr = saddr,
1576                 },
1577 #endif
1578                 {
1579                         .offset = 0,    /* sentinel */
1580                 }
1581         };
1582
1583         fn = fib6_node_lookup_1(root, daddr ? args : args + 1);
1584         if (!fn || fn->fn_flags & RTN_TL_ROOT)
1585                 fn = root;
1586
1587         return fn;
1588 }
1589
1590 /*
1591  *      Get node with specified destination prefix (and source prefix,
1592  *      if subtrees are used)
1593  *      exact_match == true means we try to find fn with exact match of
1594  *      the passed in prefix addr
1595  *      exact_match == false means we try to find fn with longest prefix
1596  *      match of the passed in prefix addr. This is useful for finding fn
1597  *      for cached route as it will be stored in the exception table under
1598  *      the node with longest prefix length.
1599  */
1600
1601
1602 static struct fib6_node *fib6_locate_1(struct fib6_node *root,
1603                                        const struct in6_addr *addr,
1604                                        int plen, int offset,
1605                                        bool exact_match)
1606 {
1607         struct fib6_node *fn, *prev = NULL;
1608
1609         for (fn = root; fn ; ) {
1610                 struct fib6_info *leaf = rcu_dereference(fn->leaf);
1611                 struct rt6key *key;
1612
1613                 /* This node is being deleted */
1614                 if (!leaf) {
1615                         if (plen <= fn->fn_bit)
1616                                 goto out;
1617                         else
1618                                 goto next;
1619                 }
1620
1621                 key = (struct rt6key *)((u8 *)leaf + offset);
1622
1623                 /*
1624                  *      Prefix match
1625                  */
1626                 if (plen < fn->fn_bit ||
1627                     !ipv6_prefix_equal(&key->addr, addr, fn->fn_bit))
1628                         goto out;
1629
1630                 if (plen == fn->fn_bit)
1631                         return fn;
1632
1633                 if (fn->fn_flags & RTN_RTINFO)
1634                         prev = fn;
1635
1636 next:
1637                 /*
1638                  *      We have more bits to go
1639                  */
1640                 if (addr_bit_set(addr, fn->fn_bit))
1641                         fn = rcu_dereference(fn->right);
1642                 else
1643                         fn = rcu_dereference(fn->left);
1644         }
1645 out:
1646         if (exact_match)
1647                 return NULL;
1648         else
1649                 return prev;
1650 }
1651
1652 struct fib6_node *fib6_locate(struct fib6_node *root,
1653                               const struct in6_addr *daddr, int dst_len,
1654                               const struct in6_addr *saddr, int src_len,
1655                               bool exact_match)
1656 {
1657         struct fib6_node *fn;
1658
1659         fn = fib6_locate_1(root, daddr, dst_len,
1660                            offsetof(struct fib6_info, fib6_dst),
1661                            exact_match);
1662
1663 #ifdef CONFIG_IPV6_SUBTREES
1664         if (src_len) {
1665                 WARN_ON(saddr == NULL);
1666                 if (fn) {
1667                         struct fib6_node *subtree = FIB6_SUBTREE(fn);
1668
1669                         if (subtree) {
1670                                 fn = fib6_locate_1(subtree, saddr, src_len,
1671                                            offsetof(struct fib6_info, fib6_src),
1672                                            exact_match);
1673                         }
1674                 }
1675         }
1676 #endif
1677
1678         if (fn && fn->fn_flags & RTN_RTINFO)
1679                 return fn;
1680
1681         return NULL;
1682 }
1683
1684
1685 /*
1686  *      Deletion
1687  *
1688  */
1689
1690 static struct fib6_info *fib6_find_prefix(struct net *net,
1691                                          struct fib6_table *table,
1692                                          struct fib6_node *fn)
1693 {
1694         struct fib6_node *child_left, *child_right;
1695
1696         if (fn->fn_flags & RTN_ROOT)
1697                 return net->ipv6.fib6_null_entry;
1698
1699         while (fn) {
1700                 child_left = rcu_dereference_protected(fn->left,
1701                                     lockdep_is_held(&table->tb6_lock));
1702                 child_right = rcu_dereference_protected(fn->right,
1703                                     lockdep_is_held(&table->tb6_lock));
1704                 if (child_left)
1705                         return rcu_dereference_protected(child_left->leaf,
1706                                         lockdep_is_held(&table->tb6_lock));
1707                 if (child_right)
1708                         return rcu_dereference_protected(child_right->leaf,
1709                                         lockdep_is_held(&table->tb6_lock));
1710
1711                 fn = FIB6_SUBTREE(fn);
1712         }
1713         return NULL;
1714 }
1715
1716 /*
1717  *      Called to trim the tree of intermediate nodes when possible. "fn"
1718  *      is the node we want to try and remove.
1719  *      Need to own table->tb6_lock
1720  */
1721
1722 static struct fib6_node *fib6_repair_tree(struct net *net,
1723                                           struct fib6_table *table,
1724                                           struct fib6_node *fn)
1725 {
1726         int children;
1727         int nstate;
1728         struct fib6_node *child;
1729         struct fib6_walker *w;
1730         int iter = 0;
1731
1732         /* Set fn->leaf to null_entry for root node. */
1733         if (fn->fn_flags & RTN_TL_ROOT) {
1734                 rcu_assign_pointer(fn->leaf, net->ipv6.fib6_null_entry);
1735                 return fn;
1736         }
1737
1738         for (;;) {
1739                 struct fib6_node *fn_r = rcu_dereference_protected(fn->right,
1740                                             lockdep_is_held(&table->tb6_lock));
1741                 struct fib6_node *fn_l = rcu_dereference_protected(fn->left,
1742                                             lockdep_is_held(&table->tb6_lock));
1743                 struct fib6_node *pn = rcu_dereference_protected(fn->parent,
1744                                             lockdep_is_held(&table->tb6_lock));
1745                 struct fib6_node *pn_r = rcu_dereference_protected(pn->right,
1746                                             lockdep_is_held(&table->tb6_lock));
1747                 struct fib6_node *pn_l = rcu_dereference_protected(pn->left,
1748                                             lockdep_is_held(&table->tb6_lock));
1749                 struct fib6_info *fn_leaf = rcu_dereference_protected(fn->leaf,
1750                                             lockdep_is_held(&table->tb6_lock));
1751                 struct fib6_info *pn_leaf = rcu_dereference_protected(pn->leaf,
1752                                             lockdep_is_held(&table->tb6_lock));
1753                 struct fib6_info *new_fn_leaf;
1754
1755                 RT6_TRACE("fixing tree: plen=%d iter=%d\n", fn->fn_bit, iter);
1756                 iter++;
1757
1758                 WARN_ON(fn->fn_flags & RTN_RTINFO);
1759                 WARN_ON(fn->fn_flags & RTN_TL_ROOT);
1760                 WARN_ON(fn_leaf);
1761
1762                 children = 0;
1763                 child = NULL;
1764                 if (fn_r)
1765                         child = fn_r, children |= 1;
1766                 if (fn_l)
1767                         child = fn_l, children |= 2;
1768
1769                 if (children == 3 || FIB6_SUBTREE(fn)
1770 #ifdef CONFIG_IPV6_SUBTREES
1771                     /* Subtree root (i.e. fn) may have one child */
1772                     || (children && fn->fn_flags & RTN_ROOT)
1773 #endif
1774                     ) {
1775                         new_fn_leaf = fib6_find_prefix(net, table, fn);
1776 #if RT6_DEBUG >= 2
1777                         if (!new_fn_leaf) {
1778                                 WARN_ON(!new_fn_leaf);
1779                                 new_fn_leaf = net->ipv6.fib6_null_entry;
1780                         }
1781 #endif
1782                         fib6_info_hold(new_fn_leaf);
1783                         rcu_assign_pointer(fn->leaf, new_fn_leaf);
1784                         return pn;
1785                 }
1786
1787 #ifdef CONFIG_IPV6_SUBTREES
1788                 if (FIB6_SUBTREE(pn) == fn) {
1789                         WARN_ON(!(fn->fn_flags & RTN_ROOT));
1790                         RCU_INIT_POINTER(pn->subtree, NULL);
1791                         nstate = FWS_L;
1792                 } else {
1793                         WARN_ON(fn->fn_flags & RTN_ROOT);
1794 #endif
1795                         if (pn_r == fn)
1796                                 rcu_assign_pointer(pn->right, child);
1797                         else if (pn_l == fn)
1798                                 rcu_assign_pointer(pn->left, child);
1799 #if RT6_DEBUG >= 2
1800                         else
1801                                 WARN_ON(1);
1802 #endif
1803                         if (child)
1804                                 rcu_assign_pointer(child->parent, pn);
1805                         nstate = FWS_R;
1806 #ifdef CONFIG_IPV6_SUBTREES
1807                 }
1808 #endif
1809
1810                 read_lock(&net->ipv6.fib6_walker_lock);
1811                 FOR_WALKERS(net, w) {
1812                         if (!child) {
1813                                 if (w->node == fn) {
1814                                         RT6_TRACE("W %p adjusted by delnode 1, s=%d/%d\n", w, w->state, nstate);
1815                                         w->node = pn;
1816                                         w->state = nstate;
1817                                 }
1818                         } else {
1819                                 if (w->node == fn) {
1820                                         w->node = child;
1821                                         if (children&2) {
1822                                                 RT6_TRACE("W %p adjusted by delnode 2, s=%d\n", w, w->state);
1823                                                 w->state = w->state >= FWS_R ? FWS_U : FWS_INIT;
1824                                         } else {
1825                                                 RT6_TRACE("W %p adjusted by delnode 2, s=%d\n", w, w->state);
1826                                                 w->state = w->state >= FWS_C ? FWS_U : FWS_INIT;
1827                                         }
1828                                 }
1829                         }
1830                 }
1831                 read_unlock(&net->ipv6.fib6_walker_lock);
1832
1833                 node_free(net, fn);
1834                 if (pn->fn_flags & RTN_RTINFO || FIB6_SUBTREE(pn))
1835                         return pn;
1836
1837                 RCU_INIT_POINTER(pn->leaf, NULL);
1838                 fib6_info_release(pn_leaf);
1839                 fn = pn;
1840         }
1841 }
1842
1843 static void fib6_del_route(struct fib6_table *table, struct fib6_node *fn,
1844                            struct fib6_info __rcu **rtp, struct nl_info *info)
1845 {
1846         struct fib6_walker *w;
1847         struct fib6_info *rt = rcu_dereference_protected(*rtp,
1848                                     lockdep_is_held(&table->tb6_lock));
1849         struct net *net = info->nl_net;
1850
1851         RT6_TRACE("fib6_del_route\n");
1852
1853         /* Unlink it */
1854         *rtp = rt->fib6_next;
1855         rt->fib6_node = NULL;
1856         net->ipv6.rt6_stats->fib_rt_entries--;
1857         net->ipv6.rt6_stats->fib_discarded_routes++;
1858
1859         /* Flush all cached dst in exception table */
1860         rt6_flush_exceptions(rt);
1861
1862         /* Reset round-robin state, if necessary */
1863         if (rcu_access_pointer(fn->rr_ptr) == rt)
1864                 fn->rr_ptr = NULL;
1865
1866         /* Remove this entry from other siblings */
1867         if (rt->fib6_nsiblings) {
1868                 struct fib6_info *sibling, *next_sibling;
1869
1870                 list_for_each_entry_safe(sibling, next_sibling,
1871                                          &rt->fib6_siblings, fib6_siblings)
1872                         sibling->fib6_nsiblings--;
1873                 rt->fib6_nsiblings = 0;
1874                 list_del_init(&rt->fib6_siblings);
1875                 rt6_multipath_rebalance(next_sibling);
1876         }
1877
1878         /* Adjust walkers */
1879         read_lock(&net->ipv6.fib6_walker_lock);
1880         FOR_WALKERS(net, w) {
1881                 if (w->state == FWS_C && w->leaf == rt) {
1882                         RT6_TRACE("walker %p adjusted by delroute\n", w);
1883                         w->leaf = rcu_dereference_protected(rt->fib6_next,
1884                                             lockdep_is_held(&table->tb6_lock));
1885                         if (!w->leaf)
1886                                 w->state = FWS_U;
1887                 }
1888         }
1889         read_unlock(&net->ipv6.fib6_walker_lock);
1890
1891         /* If it was last route, call fib6_repair_tree() to:
1892          * 1. For root node, put back null_entry as how the table was created.
1893          * 2. For other nodes, expunge its radix tree node.
1894          */
1895         if (!rcu_access_pointer(fn->leaf)) {
1896                 if (!(fn->fn_flags & RTN_TL_ROOT)) {
1897                         fn->fn_flags &= ~RTN_RTINFO;
1898                         net->ipv6.rt6_stats->fib_route_nodes--;
1899                 }
1900                 fn = fib6_repair_tree(net, table, fn);
1901         }
1902
1903         fib6_purge_rt(rt, fn, net);
1904
1905         if (!info->skip_notify_kernel)
1906                 call_fib6_entry_notifiers(net, FIB_EVENT_ENTRY_DEL, rt, NULL);
1907         if (!info->skip_notify)
1908                 inet6_rt_notify(RTM_DELROUTE, rt, info, 0);
1909
1910         fib6_info_release(rt);
1911 }
1912
1913 /* Need to own table->tb6_lock */
1914 int fib6_del(struct fib6_info *rt, struct nl_info *info)
1915 {
1916         struct fib6_node *fn = rcu_dereference_protected(rt->fib6_node,
1917                                     lockdep_is_held(&rt->fib6_table->tb6_lock));
1918         struct fib6_table *table = rt->fib6_table;
1919         struct net *net = info->nl_net;
1920         struct fib6_info __rcu **rtp;
1921         struct fib6_info __rcu **rtp_next;
1922
1923         if (!fn || rt == net->ipv6.fib6_null_entry)
1924                 return -ENOENT;
1925
1926         WARN_ON(!(fn->fn_flags & RTN_RTINFO));
1927
1928         /*
1929          *      Walk the leaf entries looking for ourself
1930          */
1931
1932         for (rtp = &fn->leaf; *rtp; rtp = rtp_next) {
1933                 struct fib6_info *cur = rcu_dereference_protected(*rtp,
1934                                         lockdep_is_held(&table->tb6_lock));
1935                 if (rt == cur) {
1936                         fib6_del_route(table, fn, rtp, info);
1937                         return 0;
1938                 }
1939                 rtp_next = &cur->fib6_next;
1940         }
1941         return -ENOENT;
1942 }
1943
1944 /*
1945  *      Tree traversal function.
1946  *
1947  *      Certainly, it is not interrupt safe.
1948  *      However, it is internally reenterable wrt itself and fib6_add/fib6_del.
1949  *      It means, that we can modify tree during walking
1950  *      and use this function for garbage collection, clone pruning,
1951  *      cleaning tree when a device goes down etc. etc.
1952  *
1953  *      It guarantees that every node will be traversed,
1954  *      and that it will be traversed only once.
1955  *
1956  *      Callback function w->func may return:
1957  *      0 -> continue walking.
1958  *      positive value -> walking is suspended (used by tree dumps,
1959  *      and probably by gc, if it will be split to several slices)
1960  *      negative value -> terminate walking.
1961  *
1962  *      The function itself returns:
1963  *      0   -> walk is complete.
1964  *      >0  -> walk is incomplete (i.e. suspended)
1965  *      <0  -> walk is terminated by an error.
1966  *
1967  *      This function is called with tb6_lock held.
1968  */
1969
1970 static int fib6_walk_continue(struct fib6_walker *w)
1971 {
1972         struct fib6_node *fn, *pn, *left, *right;
1973
1974         /* w->root should always be table->tb6_root */
1975         WARN_ON_ONCE(!(w->root->fn_flags & RTN_TL_ROOT));
1976
1977         for (;;) {
1978                 fn = w->node;
1979                 if (!fn)
1980                         return 0;
1981
1982                 switch (w->state) {
1983 #ifdef CONFIG_IPV6_SUBTREES
1984                 case FWS_S:
1985                         if (FIB6_SUBTREE(fn)) {
1986                                 w->node = FIB6_SUBTREE(fn);
1987                                 continue;
1988                         }
1989                         w->state = FWS_L;
1990 #endif
1991                         /* fall through */
1992                 case FWS_L:
1993                         left = rcu_dereference_protected(fn->left, 1);
1994                         if (left) {
1995                                 w->node = left;
1996                                 w->state = FWS_INIT;
1997                                 continue;
1998                         }
1999                         w->state = FWS_R;
2000                         /* fall through */
2001                 case FWS_R:
2002                         right = rcu_dereference_protected(fn->right, 1);
2003                         if (right) {
2004                                 w->node = right;
2005                                 w->state = FWS_INIT;
2006                                 continue;
2007                         }
2008                         w->state = FWS_C;
2009                         w->leaf = rcu_dereference_protected(fn->leaf, 1);
2010                         /* fall through */
2011                 case FWS_C:
2012                         if (w->leaf && fn->fn_flags & RTN_RTINFO) {
2013                                 int err;
2014
2015                                 if (w->skip) {
2016                                         w->skip--;
2017                                         goto skip;
2018                                 }
2019
2020                                 err = w->func(w);
2021                                 if (err)
2022                                         return err;
2023
2024                                 w->count++;
2025                                 continue;
2026                         }
2027 skip:
2028                         w->state = FWS_U;
2029                         /* fall through */
2030                 case FWS_U:
2031                         if (fn == w->root)
2032                                 return 0;
2033                         pn = rcu_dereference_protected(fn->parent, 1);
2034                         left = rcu_dereference_protected(pn->left, 1);
2035                         right = rcu_dereference_protected(pn->right, 1);
2036                         w->node = pn;
2037 #ifdef CONFIG_IPV6_SUBTREES
2038                         if (FIB6_SUBTREE(pn) == fn) {
2039                                 WARN_ON(!(fn->fn_flags & RTN_ROOT));
2040                                 w->state = FWS_L;
2041                                 continue;
2042                         }
2043 #endif
2044                         if (left == fn) {
2045                                 w->state = FWS_R;
2046                                 continue;
2047                         }
2048                         if (right == fn) {
2049                                 w->state = FWS_C;
2050                                 w->leaf = rcu_dereference_protected(w->node->leaf, 1);
2051                                 continue;
2052                         }
2053 #if RT6_DEBUG >= 2
2054                         WARN_ON(1);
2055 #endif
2056                 }
2057         }
2058 }
2059
2060 static int fib6_walk(struct net *net, struct fib6_walker *w)
2061 {
2062         int res;
2063
2064         w->state = FWS_INIT;
2065         w->node = w->root;
2066
2067         fib6_walker_link(net, w);
2068         res = fib6_walk_continue(w);
2069         if (res <= 0)
2070                 fib6_walker_unlink(net, w);
2071         return res;
2072 }
2073
2074 static int fib6_clean_node(struct fib6_walker *w)
2075 {
2076         int res;
2077         struct fib6_info *rt;
2078         struct fib6_cleaner *c = container_of(w, struct fib6_cleaner, w);
2079         struct nl_info info = {
2080                 .nl_net = c->net,
2081                 .skip_notify = c->skip_notify,
2082         };
2083
2084         if (c->sernum != FIB6_NO_SERNUM_CHANGE &&
2085             w->node->fn_sernum != c->sernum)
2086                 w->node->fn_sernum = c->sernum;
2087
2088         if (!c->func) {
2089                 WARN_ON_ONCE(c->sernum == FIB6_NO_SERNUM_CHANGE);
2090                 w->leaf = NULL;
2091                 return 0;
2092         }
2093
2094         for_each_fib6_walker_rt(w) {
2095                 res = c->func(rt, c->arg);
2096                 if (res == -1) {
2097                         w->leaf = rt;
2098                         res = fib6_del(rt, &info);
2099                         if (res) {
2100 #if RT6_DEBUG >= 2
2101                                 pr_debug("%s: del failed: rt=%p@%p err=%d\n",
2102                                          __func__, rt,
2103                                          rcu_access_pointer(rt->fib6_node),
2104                                          res);
2105 #endif
2106                                 continue;
2107                         }
2108                         return 0;
2109                 } else if (res == -2) {
2110                         if (WARN_ON(!rt->fib6_nsiblings))
2111                                 continue;
2112                         rt = list_last_entry(&rt->fib6_siblings,
2113                                              struct fib6_info, fib6_siblings);
2114                         continue;
2115                 }
2116                 WARN_ON(res != 0);
2117         }
2118         w->leaf = rt;
2119         return 0;
2120 }
2121
2122 /*
2123  *      Convenient frontend to tree walker.
2124  *
2125  *      func is called on each route.
2126  *              It may return -2 -> skip multipath route.
2127  *                            -1 -> delete this route.
2128  *                            0  -> continue walking
2129  */
2130
2131 static void fib6_clean_tree(struct net *net, struct fib6_node *root,
2132                             int (*func)(struct fib6_info *, void *arg),
2133                             int sernum, void *arg, bool skip_notify)
2134 {
2135         struct fib6_cleaner c;
2136
2137         c.w.root = root;
2138         c.w.func = fib6_clean_node;
2139         c.w.count = 0;
2140         c.w.skip = 0;
2141         c.w.skip_in_node = 0;
2142         c.func = func;
2143         c.sernum = sernum;
2144         c.arg = arg;
2145         c.net = net;
2146         c.skip_notify = skip_notify;
2147
2148         fib6_walk(net, &c.w);
2149 }
2150
2151 static void __fib6_clean_all(struct net *net,
2152                              int (*func)(struct fib6_info *, void *),
2153                              int sernum, void *arg, bool skip_notify)
2154 {
2155         struct fib6_table *table;
2156         struct hlist_head *head;
2157         unsigned int h;
2158
2159         rcu_read_lock();
2160         for (h = 0; h < FIB6_TABLE_HASHSZ; h++) {
2161                 head = &net->ipv6.fib_table_hash[h];
2162                 hlist_for_each_entry_rcu(table, head, tb6_hlist) {
2163                         spin_lock_bh(&table->tb6_lock);
2164                         fib6_clean_tree(net, &table->tb6_root,
2165                                         func, sernum, arg, skip_notify);
2166                         spin_unlock_bh(&table->tb6_lock);
2167                 }
2168         }
2169         rcu_read_unlock();
2170 }
2171
2172 void fib6_clean_all(struct net *net, int (*func)(struct fib6_info *, void *),
2173                     void *arg)
2174 {
2175         __fib6_clean_all(net, func, FIB6_NO_SERNUM_CHANGE, arg, false);
2176 }
2177
2178 void fib6_clean_all_skip_notify(struct net *net,
2179                                 int (*func)(struct fib6_info *, void *),
2180                                 void *arg)
2181 {
2182         __fib6_clean_all(net, func, FIB6_NO_SERNUM_CHANGE, arg, true);
2183 }
2184
2185 static void fib6_flush_trees(struct net *net)
2186 {
2187         int new_sernum = fib6_new_sernum(net);
2188
2189         __fib6_clean_all(net, NULL, new_sernum, NULL, false);
2190 }
2191
2192 /*
2193  *      Garbage collection
2194  */
2195
2196 static int fib6_age(struct fib6_info *rt, void *arg)
2197 {
2198         struct fib6_gc_args *gc_args = arg;
2199         unsigned long now = jiffies;
2200
2201         /*
2202          *      check addrconf expiration here.
2203          *      Routes are expired even if they are in use.
2204          */
2205
2206         if (rt->fib6_flags & RTF_EXPIRES && rt->expires) {
2207                 if (time_after(now, rt->expires)) {
2208                         RT6_TRACE("expiring %p\n", rt);
2209                         return -1;
2210                 }
2211                 gc_args->more++;
2212         }
2213
2214         /*      Also age clones in the exception table.
2215          *      Note, that clones are aged out
2216          *      only if they are not in use now.
2217          */
2218         rt6_age_exceptions(rt, gc_args, now);
2219
2220         return 0;
2221 }
2222
2223 void fib6_run_gc(unsigned long expires, struct net *net, bool force)
2224 {
2225         struct fib6_gc_args gc_args;
2226         unsigned long now;
2227
2228         if (force) {
2229                 spin_lock_bh(&net->ipv6.fib6_gc_lock);
2230         } else if (!spin_trylock_bh(&net->ipv6.fib6_gc_lock)) {
2231                 mod_timer(&net->ipv6.ip6_fib_timer, jiffies + HZ);
2232                 return;
2233         }
2234         gc_args.timeout = expires ? (int)expires :
2235                           net->ipv6.sysctl.ip6_rt_gc_interval;
2236         gc_args.more = 0;
2237
2238         fib6_clean_all(net, fib6_age, &gc_args);
2239         now = jiffies;
2240         net->ipv6.ip6_rt_last_gc = now;
2241
2242         if (gc_args.more)
2243                 mod_timer(&net->ipv6.ip6_fib_timer,
2244                           round_jiffies(now
2245                                         + net->ipv6.sysctl.ip6_rt_gc_interval));
2246         else
2247                 del_timer(&net->ipv6.ip6_fib_timer);
2248         spin_unlock_bh(&net->ipv6.fib6_gc_lock);
2249 }
2250
2251 static void fib6_gc_timer_cb(struct timer_list *t)
2252 {
2253         struct net *arg = from_timer(arg, t, ipv6.ip6_fib_timer);
2254
2255         fib6_run_gc(0, arg, true);
2256 }
2257
2258 static int __net_init fib6_net_init(struct net *net)
2259 {
2260         size_t size = sizeof(struct hlist_head) * FIB6_TABLE_HASHSZ;
2261         int err;
2262
2263         err = fib6_notifier_init(net);
2264         if (err)
2265                 return err;
2266
2267         spin_lock_init(&net->ipv6.fib6_gc_lock);
2268         rwlock_init(&net->ipv6.fib6_walker_lock);
2269         INIT_LIST_HEAD(&net->ipv6.fib6_walkers);
2270         timer_setup(&net->ipv6.ip6_fib_timer, fib6_gc_timer_cb, 0);
2271
2272         net->ipv6.rt6_stats = kzalloc(sizeof(*net->ipv6.rt6_stats), GFP_KERNEL);
2273         if (!net->ipv6.rt6_stats)
2274                 goto out_timer;
2275
2276         /* Avoid false sharing : Use at least a full cache line */
2277         size = max_t(size_t, size, L1_CACHE_BYTES);
2278
2279         net->ipv6.fib_table_hash = kzalloc(size, GFP_KERNEL);
2280         if (!net->ipv6.fib_table_hash)
2281                 goto out_rt6_stats;
2282
2283         net->ipv6.fib6_main_tbl = kzalloc(sizeof(*net->ipv6.fib6_main_tbl),
2284                                           GFP_KERNEL);
2285         if (!net->ipv6.fib6_main_tbl)
2286                 goto out_fib_table_hash;
2287
2288         net->ipv6.fib6_main_tbl->tb6_id = RT6_TABLE_MAIN;
2289         rcu_assign_pointer(net->ipv6.fib6_main_tbl->tb6_root.leaf,
2290                            net->ipv6.fib6_null_entry);
2291         net->ipv6.fib6_main_tbl->tb6_root.fn_flags =
2292                 RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
2293         inet_peer_base_init(&net->ipv6.fib6_main_tbl->tb6_peers);
2294
2295 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
2296         net->ipv6.fib6_local_tbl = kzalloc(sizeof(*net->ipv6.fib6_local_tbl),
2297                                            GFP_KERNEL);
2298         if (!net->ipv6.fib6_local_tbl)
2299                 goto out_fib6_main_tbl;
2300         net->ipv6.fib6_local_tbl->tb6_id = RT6_TABLE_LOCAL;
2301         rcu_assign_pointer(net->ipv6.fib6_local_tbl->tb6_root.leaf,
2302                            net->ipv6.fib6_null_entry);
2303         net->ipv6.fib6_local_tbl->tb6_root.fn_flags =
2304                 RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
2305         inet_peer_base_init(&net->ipv6.fib6_local_tbl->tb6_peers);
2306 #endif
2307         fib6_tables_init(net);
2308
2309         return 0;
2310
2311 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
2312 out_fib6_main_tbl:
2313         kfree(net->ipv6.fib6_main_tbl);
2314 #endif
2315 out_fib_table_hash:
2316         kfree(net->ipv6.fib_table_hash);
2317 out_rt6_stats:
2318         kfree(net->ipv6.rt6_stats);
2319 out_timer:
2320         fib6_notifier_exit(net);
2321         return -ENOMEM;
2322 }
2323
2324 static void fib6_net_exit(struct net *net)
2325 {
2326         unsigned int i;
2327
2328         del_timer_sync(&net->ipv6.ip6_fib_timer);
2329
2330         for (i = 0; i < FIB6_TABLE_HASHSZ; i++) {
2331                 struct hlist_head *head = &net->ipv6.fib_table_hash[i];
2332                 struct hlist_node *tmp;
2333                 struct fib6_table *tb;
2334
2335                 hlist_for_each_entry_safe(tb, tmp, head, tb6_hlist) {
2336                         hlist_del(&tb->tb6_hlist);
2337                         fib6_free_table(tb);
2338                 }
2339         }
2340
2341         kfree(net->ipv6.fib_table_hash);
2342         kfree(net->ipv6.rt6_stats);
2343         fib6_notifier_exit(net);
2344 }
2345
2346 static struct pernet_operations fib6_net_ops = {
2347         .init = fib6_net_init,
2348         .exit = fib6_net_exit,
2349 };
2350
2351 int __init fib6_init(void)
2352 {
2353         int ret = -ENOMEM;
2354
2355         fib6_node_kmem = kmem_cache_create("fib6_nodes",
2356                                            sizeof(struct fib6_node),
2357                                            0, SLAB_HWCACHE_ALIGN,
2358                                            NULL);
2359         if (!fib6_node_kmem)
2360                 goto out;
2361
2362         ret = register_pernet_subsys(&fib6_net_ops);
2363         if (ret)
2364                 goto out_kmem_cache_create;
2365
2366         ret = rtnl_register_module(THIS_MODULE, PF_INET6, RTM_GETROUTE, NULL,
2367                                    inet6_dump_fib, 0);
2368         if (ret)
2369                 goto out_unregister_subsys;
2370
2371         __fib6_flush_trees = fib6_flush_trees;
2372 out:
2373         return ret;
2374
2375 out_unregister_subsys:
2376         unregister_pernet_subsys(&fib6_net_ops);
2377 out_kmem_cache_create:
2378         kmem_cache_destroy(fib6_node_kmem);
2379         goto out;
2380 }
2381
2382 void fib6_gc_cleanup(void)
2383 {
2384         unregister_pernet_subsys(&fib6_net_ops);
2385         kmem_cache_destroy(fib6_node_kmem);
2386 }
2387
2388 #ifdef CONFIG_PROC_FS
2389 static int ipv6_route_seq_show(struct seq_file *seq, void *v)
2390 {
2391         struct fib6_info *rt = v;
2392         struct ipv6_route_iter *iter = seq->private;
2393         struct fib6_nh *fib6_nh = rt->fib6_nh;
2394         unsigned int flags = rt->fib6_flags;
2395         const struct net_device *dev;
2396
2397         if (rt->nh)
2398                 fib6_nh = nexthop_fib6_nh(rt->nh);
2399
2400         seq_printf(seq, "%pi6 %02x ", &rt->fib6_dst.addr, rt->fib6_dst.plen);
2401
2402 #ifdef CONFIG_IPV6_SUBTREES
2403         seq_printf(seq, "%pi6 %02x ", &rt->fib6_src.addr, rt->fib6_src.plen);
2404 #else
2405         seq_puts(seq, "00000000000000000000000000000000 00 ");
2406 #endif
2407         if (fib6_nh->fib_nh_gw_family) {
2408                 flags |= RTF_GATEWAY;
2409                 seq_printf(seq, "%pi6", &fib6_nh->fib_nh_gw6);
2410         } else {
2411                 seq_puts(seq, "00000000000000000000000000000000");
2412         }
2413
2414         dev = fib6_nh->fib_nh_dev;
2415         seq_printf(seq, " %08x %08x %08x %08x %8s\n",
2416                    rt->fib6_metric, refcount_read(&rt->fib6_ref), 0,
2417                    flags, dev ? dev->name : "");
2418         iter->w.leaf = NULL;
2419         return 0;
2420 }
2421
2422 static int ipv6_route_yield(struct fib6_walker *w)
2423 {
2424         struct ipv6_route_iter *iter = w->args;
2425
2426         if (!iter->skip)
2427                 return 1;
2428
2429         do {
2430                 iter->w.leaf = rcu_dereference_protected(
2431                                 iter->w.leaf->fib6_next,
2432                                 lockdep_is_held(&iter->tbl->tb6_lock));
2433                 iter->skip--;
2434                 if (!iter->skip && iter->w.leaf)
2435                         return 1;
2436         } while (iter->w.leaf);
2437
2438         return 0;
2439 }
2440
2441 static void ipv6_route_seq_setup_walk(struct ipv6_route_iter *iter,
2442                                       struct net *net)
2443 {
2444         memset(&iter->w, 0, sizeof(iter->w));
2445         iter->w.func = ipv6_route_yield;
2446         iter->w.root = &iter->tbl->tb6_root;
2447         iter->w.state = FWS_INIT;
2448         iter->w.node = iter->w.root;
2449         iter->w.args = iter;
2450         iter->sernum = iter->w.root->fn_sernum;
2451         INIT_LIST_HEAD(&iter->w.lh);
2452         fib6_walker_link(net, &iter->w);
2453 }
2454
2455 static struct fib6_table *ipv6_route_seq_next_table(struct fib6_table *tbl,
2456                                                     struct net *net)
2457 {
2458         unsigned int h;
2459         struct hlist_node *node;
2460
2461         if (tbl) {
2462                 h = (tbl->tb6_id & (FIB6_TABLE_HASHSZ - 1)) + 1;
2463                 node = rcu_dereference_bh(hlist_next_rcu(&tbl->tb6_hlist));
2464         } else {
2465                 h = 0;
2466                 node = NULL;
2467         }
2468
2469         while (!node && h < FIB6_TABLE_HASHSZ) {
2470                 node = rcu_dereference_bh(
2471                         hlist_first_rcu(&net->ipv6.fib_table_hash[h++]));
2472         }
2473         return hlist_entry_safe(node, struct fib6_table, tb6_hlist);
2474 }
2475
2476 static void ipv6_route_check_sernum(struct ipv6_route_iter *iter)
2477 {
2478         if (iter->sernum != iter->w.root->fn_sernum) {
2479                 iter->sernum = iter->w.root->fn_sernum;
2480                 iter->w.state = FWS_INIT;
2481                 iter->w.node = iter->w.root;
2482                 WARN_ON(iter->w.skip);
2483                 iter->w.skip = iter->w.count;
2484         }
2485 }
2486
2487 static void *ipv6_route_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2488 {
2489         int r;
2490         struct fib6_info *n;
2491         struct net *net = seq_file_net(seq);
2492         struct ipv6_route_iter *iter = seq->private;
2493
2494         if (!v)
2495                 goto iter_table;
2496
2497         n = rcu_dereference_bh(((struct fib6_info *)v)->fib6_next);
2498         if (n) {
2499                 ++*pos;
2500                 return n;
2501         }
2502
2503 iter_table:
2504         ipv6_route_check_sernum(iter);
2505         spin_lock_bh(&iter->tbl->tb6_lock);
2506         r = fib6_walk_continue(&iter->w);
2507         spin_unlock_bh(&iter->tbl->tb6_lock);
2508         if (r > 0) {
2509                 if (v)
2510                         ++*pos;
2511                 return iter->w.leaf;
2512         } else if (r < 0) {
2513                 fib6_walker_unlink(net, &iter->w);
2514                 return NULL;
2515         }
2516         fib6_walker_unlink(net, &iter->w);
2517
2518         iter->tbl = ipv6_route_seq_next_table(iter->tbl, net);
2519         if (!iter->tbl)
2520                 return NULL;
2521
2522         ipv6_route_seq_setup_walk(iter, net);
2523         goto iter_table;
2524 }
2525
2526 static void *ipv6_route_seq_start(struct seq_file *seq, loff_t *pos)
2527         __acquires(RCU_BH)
2528 {
2529         struct net *net = seq_file_net(seq);
2530         struct ipv6_route_iter *iter = seq->private;
2531
2532         rcu_read_lock_bh();
2533         iter->tbl = ipv6_route_seq_next_table(NULL, net);
2534         iter->skip = *pos;
2535
2536         if (iter->tbl) {
2537                 ipv6_route_seq_setup_walk(iter, net);
2538                 return ipv6_route_seq_next(seq, NULL, pos);
2539         } else {
2540                 return NULL;
2541         }
2542 }
2543
2544 static bool ipv6_route_iter_active(struct ipv6_route_iter *iter)
2545 {
2546         struct fib6_walker *w = &iter->w;
2547         return w->node && !(w->state == FWS_U && w->node == w->root);
2548 }
2549
2550 static void ipv6_route_seq_stop(struct seq_file *seq, void *v)
2551         __releases(RCU_BH)
2552 {
2553         struct net *net = seq_file_net(seq);
2554         struct ipv6_route_iter *iter = seq->private;
2555
2556         if (ipv6_route_iter_active(iter))
2557                 fib6_walker_unlink(net, &iter->w);
2558
2559         rcu_read_unlock_bh();
2560 }
2561
2562 const struct seq_operations ipv6_route_seq_ops = {
2563         .start  = ipv6_route_seq_start,
2564         .next   = ipv6_route_seq_next,
2565         .stop   = ipv6_route_seq_stop,
2566         .show   = ipv6_route_seq_show
2567 };
2568 #endif /* CONFIG_PROC_FS */