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)
 147 {
 148         struct fib6_info *f6i;
 149
 150         f6i = kzalloc(sizeof(*f6i), gfp_flags);
 151         if (!f6i)
 152                 return NULL;
 153
 154         f6i->rt6i_pcpu = alloc_percpu_gfp(struct rt6_info *, gfp_flags);
 155         if (!f6i->rt6i_pcpu) {
 156                 kfree(f6i);
 157                 return NULL;
 158         }
 159
 160         INIT_LIST_HEAD(&f6i->fib6_siblings);
 161         refcount_set(&f6i->fib6_ref, 1);
 162
 163         return f6i;
 164 }
 165
 166 void fib6_info_destroy_rcu(struct rcu_head *head)
 167 {
 168         struct fib6_info *f6i = container_of(head, struct fib6_info, rcu);
 169         struct rt6_exception_bucket *bucket;
 170
 171         WARN_ON(f6i->fib6_node);
 172
 173         bucket = rcu_dereference_protected(f6i->rt6i_exception_bucket, 1);
 174         kfree(bucket);
 175
 176         if (f6i->rt6i_pcpu) {
 177                 int cpu;
 178
 179                 for_each_possible_cpu(cpu) {
 180                         struct rt6_info **ppcpu_rt;
 181                         struct rt6_info *pcpu_rt;
 182
 183                         ppcpu_rt = per_cpu_ptr(f6i->rt6i_pcpu, cpu);
 184                         pcpu_rt = *ppcpu_rt;
 185                         if (pcpu_rt) {
 186                                 dst_dev_put(&pcpu_rt->dst);
 187                                 dst_release(&pcpu_rt->dst);
 188                                 *ppcpu_rt = NULL;
 189                         }
 190                 }
 191
 192                 free_percpu(f6i->rt6i_pcpu);
 193         }
 194
 195         fib6_nh_release(&f6i->fib6_nh);
 196
 197         ip_fib_metrics_put(f6i->fib6_metrics);
 198
 199         kfree(f6i);
 200 }
 201 EXPORT_SYMBOL_GPL(fib6_info_destroy_rcu);
 202
 203 static struct fib6_node *node_alloc(struct net *net)
 204 {
 205         struct fib6_node *fn;
 206
 207         fn = kmem_cache_zalloc(fib6_node_kmem, GFP_ATOMIC);
 208         if (fn)
 209                 net->ipv6.rt6_stats->fib_nodes++;
 210
 211         return fn;
 212 }
 213
 214 static void node_free_immediate(struct net *net, struct fib6_node *fn)
 215 {
 216         kmem_cache_free(fib6_node_kmem, fn);
 217         net->ipv6.rt6_stats->fib_nodes--;
 218 }
 219
 220 static void node_free_rcu(struct rcu_head *head)
 221 {
 222         struct fib6_node *fn = container_of(head, struct fib6_node, rcu);
 223
 224         kmem_cache_free(fib6_node_kmem, fn);
 225 }
 226
 227 static void node_free(struct net *net, struct fib6_node *fn)
 228 {
 229         call_rcu(&fn->rcu, node_free_rcu);
 230         net->ipv6.rt6_stats->fib_nodes--;
 231 }
 232
 233 static void fib6_free_table(struct fib6_table *table)
 234 {
 235         inetpeer_invalidate_tree(&table->tb6_peers);
 236         kfree(table);
 237 }
 238
 239 static void fib6_link_table(struct net *net, struct fib6_table *tb)
 240 {
 241         unsigned int h;
 242
 243         /*
 244          * Initialize table lock at a single place to give lockdep a key,
 245          * tables aren't visible prior to being linked to the list.
 246          */
 247         spin_lock_init(&tb->tb6_lock);
 248         h = tb->tb6_id & (FIB6_TABLE_HASHSZ - 1);
 249
 250         /*
 251          * No protection necessary, this is the only list mutatation
 252          * operation, tables never disappear once they exist.
 253          */
 254         hlist_add_head_rcu(&tb->tb6_hlist, &net->ipv6.fib_table_hash[h]);
 255 }
 256
 257 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
 258
 259 static struct fib6_table *fib6_alloc_table(struct net *net, u32 id)
 260 {
 261         struct fib6_table *table;
 262
 263         table = kzalloc(sizeof(*table), GFP_ATOMIC);
 264         if (table) {
 265                 table->tb6_id = id;
 266                 rcu_assign_pointer(table->tb6_root.leaf,
 267                                    net->ipv6.fib6_null_entry);
 268                 table->tb6_root.fn_flags = RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
 269                 inet_peer_base_init(&table->tb6_peers);
 270         }
 271
 272         return table;
 273 }
 274
 275 struct fib6_table *fib6_new_table(struct net *net, u32 id)
 276 {
 277         struct fib6_table *tb;
 278
 279         if (id == 0)
 280                 id = RT6_TABLE_MAIN;
 281         tb = fib6_get_table(net, id);
 282         if (tb)
 283                 return tb;
 284
 285         tb = fib6_alloc_table(net, id);
 286         if (tb)
 287                 fib6_link_table(net, tb);
 288
 289         return tb;
 290 }
 291 EXPORT_SYMBOL_GPL(fib6_new_table);
 292
 293 struct fib6_table *fib6_get_table(struct net *net, u32 id)
 294 {
 295         struct fib6_table *tb;
 296         struct hlist_head *head;
 297         unsigned int h;
 298
 299         if (id == 0)
 300                 id = RT6_TABLE_MAIN;
 301         h = id & (FIB6_TABLE_HASHSZ - 1);
 302         rcu_read_lock();
 303         head = &net->ipv6.fib_table_hash[h];
 304         hlist_for_each_entry_rcu(tb, head, tb6_hlist) {
 305                 if (tb->tb6_id == id) {
 306                         rcu_read_unlock();
 307                         return tb;
 308                 }
 309         }
 310         rcu_read_unlock();
 311
 312         return NULL;
 313 }
 314 EXPORT_SYMBOL_GPL(fib6_get_table);
 315
 316 static void __net_init fib6_tables_init(struct net *net)
 317 {
 318         fib6_link_table(net, net->ipv6.fib6_main_tbl);
 319         fib6_link_table(net, net->ipv6.fib6_local_tbl);
 320 }
 321 #else
 322
 323 struct fib6_table *fib6_new_table(struct net *net, u32 id)
 324 {
 325         return fib6_get_table(net, id);
 326 }
 327
 328 struct fib6_table *fib6_get_table(struct net *net, u32 id)
 329 {
 330           return net->ipv6.fib6_main_tbl;
 331 }
 332
 333 struct dst_entry *fib6_rule_lookup(struct net *net, struct flowi6 *fl6,
 334                                    const struct sk_buff *skb,
 335                                    int flags, pol_lookup_t lookup)
 336 {
 337         struct rt6_info *rt;
 338
 339         rt = lookup(net, net->ipv6.fib6_main_tbl, fl6, skb, flags);
 340         if (rt->dst.error == -EAGAIN) {
 341                 ip6_rt_put(rt);
 342                 rt = net->ipv6.ip6_null_entry;
 343                 dst_hold(&rt->dst);
 344         }
 345
 346         return &rt->dst;
 347 }
 348
 349 /* called with rcu lock held; no reference taken on fib6_info */
 350 int fib6_lookup(struct net *net, int oif, struct flowi6 *fl6,
 351                 struct fib6_result *res, int flags)
 352 {
 353         return fib6_table_lookup(net, net->ipv6.fib6_main_tbl, oif, fl6,
 354                                  res, flags);
 355 }
 356
 357 static void __net_init fib6_tables_init(struct net *net)
 358 {
 359         fib6_link_table(net, net->ipv6.fib6_main_tbl);
 360 }
 361
 362 #endif
 363
 364 unsigned int fib6_tables_seq_read(struct net *net)
 365 {
 366         unsigned int h, fib_seq = 0;
 367
 368         rcu_read_lock();
 369         for (h = 0; h < FIB6_TABLE_HASHSZ; h++) {
 370                 struct hlist_head *head = &net->ipv6.fib_table_hash[h];
 371                 struct fib6_table *tb;
 372
 373                 hlist_for_each_entry_rcu(tb, head, tb6_hlist)
 374                         fib_seq += tb->fib_seq;
 375         }
 376         rcu_read_unlock();
 377
 378         return fib_seq;
 379 }
 380
 381 static int call_fib6_entry_notifier(struct notifier_block *nb, struct net *net,
 382                                     enum fib_event_type event_type,
 383                                     struct fib6_info *rt)
 384 {
 385         struct fib6_entry_notifier_info info = {
 386                 .rt = rt,
 387         };
 388
 389         return call_fib6_notifier(nb, net, event_type, &info.info);
 390 }
 391
 392 static int call_fib6_entry_notifiers(struct net *net,
 393                                      enum fib_event_type event_type,
 394                                      struct fib6_info *rt,
 395                                      struct netlink_ext_ack *extack)
 396 {
 397         struct fib6_entry_notifier_info info = {
 398                 .info.extack = extack,
 399                 .rt = rt,
 400         };
 401
 402         rt->fib6_table->fib_seq++;
 403         return call_fib6_notifiers(net, event_type, &info.info);
 404 }
 405
 406 struct fib6_dump_arg {
 407         struct net *net;
 408         struct notifier_block *nb;
 409 };
 410
 411 static void fib6_rt_dump(struct fib6_info *rt, struct fib6_dump_arg *arg)
 412 {
 413         if (rt == arg->net->ipv6.fib6_null_entry)
 414                 return;
 415         call_fib6_entry_notifier(arg->nb, arg->net, FIB_EVENT_ENTRY_ADD, rt);
 416 }
 417
 418 static int fib6_node_dump(struct fib6_walker *w)
 419 {
 420         struct fib6_info *rt;
 421
 422         for_each_fib6_walker_rt(w)
 423                 fib6_rt_dump(rt, w->args);
 424         w->leaf = NULL;
 425         return 0;
 426 }
 427
 428 static void fib6_table_dump(struct net *net, struct fib6_table *tb,
 429                             struct fib6_walker *w)
 430 {
 431         w->root = &tb->tb6_root;
 432         spin_lock_bh(&tb->tb6_lock);
 433         fib6_walk(net, w);
 434         spin_unlock_bh(&tb->tb6_lock);
 435 }
 436
 437 /* Called with rcu_read_lock() */
 438 int fib6_tables_dump(struct net *net, struct notifier_block *nb)
 439 {
 440         struct fib6_dump_arg arg;
 441         struct fib6_walker *w;
 442         unsigned int h;
 443
 444         w = kzalloc(sizeof(*w), GFP_ATOMIC);
 445         if (!w)
 446                 return -ENOMEM;
 447
 448         w->func = fib6_node_dump;
 449         arg.net = net;
 450         arg.nb = nb;
 451         w->args = &arg;
 452
 453         for (h = 0; h < FIB6_TABLE_HASHSZ; h++) {
 454                 struct hlist_head *head = &net->ipv6.fib_table_hash[h];
 455                 struct fib6_table *tb;
 456
 457                 hlist_for_each_entry_rcu(tb, head, tb6_hlist)
 458                         fib6_table_dump(net, tb, w);
 459         }
 460
 461         kfree(w);
 462
 463         return 0;
 464 }
 465
 466 static int fib6_dump_node(struct fib6_walker *w)
 467 {
 468         int res;
 469         struct fib6_info *rt;
 470
 471         for_each_fib6_walker_rt(w) {
 472                 res = rt6_dump_route(rt, w->args);
 473                 if (res < 0) {
 474                         /* Frame is full, suspend walking */
 475                         w->leaf = rt;
 476                         return 1;
 477                 }
 478
 479                 /* Multipath routes are dumped in one route with the
 480                  * RTA_MULTIPATH attribute. Jump 'rt' to point to the
 481                  * last sibling of this route (no need to dump the
 482                  * sibling routes again)
 483                  */
 484                 if (rt->fib6_nsiblings)
 485                         rt = list_last_entry(&rt->fib6_siblings,
 486                                              struct fib6_info,
 487                                              fib6_siblings);
 488         }
 489         w->leaf = NULL;
 490         return 0;
 491 }
 492
 493 static void fib6_dump_end(struct netlink_callback *cb)
 494 {
 495         struct net *net = sock_net(cb->skb->sk);
 496         struct fib6_walker *w = (void *)cb->args[2];
 497
 498         if (w) {
 499                 if (cb->args[4]) {
 500                         cb->args[4] = 0;
 501                         fib6_walker_unlink(net, w);
 502                 }
 503                 cb->args[2] = 0;
 504                 kfree(w);
 505         }
 506         cb->done = (void *)cb->args[3];
 507         cb->args[1] = 3;
 508 }
 509
 510 static int fib6_dump_done(struct netlink_callback *cb)
 511 {
 512         fib6_dump_end(cb);
 513         return cb->done ? cb->done(cb) : 0;
 514 }
 515
 516 static int fib6_dump_table(struct fib6_table *table, struct sk_buff *skb,
 517                            struct netlink_callback *cb)
 518 {
 519         struct net *net = sock_net(skb->sk);
 520         struct fib6_walker *w;
 521         int res;
 522
 523         w = (void *)cb->args[2];
 524         w->root = &table->tb6_root;
 525
 526         if (cb->args[4] == 0) {
 527                 w->count = 0;
 528                 w->skip = 0;
 529
 530                 spin_lock_bh(&table->tb6_lock);
 531                 res = fib6_walk(net, w);
 532                 spin_unlock_bh(&table->tb6_lock);
 533                 if (res > 0) {
 534                         cb->args[4] = 1;
 535                         cb->args[5] = w->root->fn_sernum;
 536                 }
 537         } else {
 538                 if (cb->args[5] != w->root->fn_sernum) {
 539                         /* Begin at the root if the tree changed */
 540                         cb->args[5] = w->root->fn_sernum;
 541                         w->state = FWS_INIT;
 542                         w->node = w->root;
 543                         w->skip = w->count;
 544                 } else
 545                         w->skip = 0;
 546
 547                 spin_lock_bh(&table->tb6_lock);
 548                 res = fib6_walk_continue(w);
 549                 spin_unlock_bh(&table->tb6_lock);
 550                 if (res <= 0) {
 551                         fib6_walker_unlink(net, w);
 552                         cb->args[4] = 0;
 553                 }
 554         }
 555
 556         return res;
 557 }
 558
 559 static int inet6_dump_fib(struct sk_buff *skb, struct netlink_callback *cb)
 560 {
 561         const struct nlmsghdr *nlh = cb->nlh;
 562         struct net *net = sock_net(skb->sk);
 563         struct rt6_rtnl_dump_arg arg = {};
 564         unsigned int h, s_h;
 565         unsigned int e = 0, s_e;
 566         struct fib6_walker *w;
 567         struct fib6_table *tb;
 568         struct hlist_head *head;
 569         int res = 0;
 570
 571         if (cb->strict_check) {
 572                 int err;
 573
 574                 err = ip_valid_fib_dump_req(net, nlh, &arg.filter, cb);
 575                 if (err < 0)
 576                         return err;
 577         } else if (nlmsg_len(nlh) >= sizeof(struct rtmsg)) {
 578                 struct rtmsg *rtm = nlmsg_data(nlh);
 579
 580                 arg.filter.flags = rtm->rtm_flags & (RTM_F_PREFIX|RTM_F_CLONED);
 581         }
 582
 583         /* fib entries are never clones */
 584         if (arg.filter.flags & RTM_F_CLONED)
 585                 goto out;
 586
 587         w = (void *)cb->args[2];
 588         if (!w) {
 589                 /* New dump:
 590                  *
 591                  * 1. hook callback destructor.
 592                  */
 593                 cb->args[3] = (long)cb->done;
 594                 cb->done = fib6_dump_done;
 595
 596                 /*
 597                  * 2. allocate and initialize walker.
 598                  */
 599                 w = kzalloc(sizeof(*w), GFP_ATOMIC);
 600                 if (!w)
 601                         return -ENOMEM;
 602                 w->func = fib6_dump_node;
 603                 cb->args[2] = (long)w;
 604         }
 605
 606         arg.skb = skb;
 607         arg.cb = cb;
 608         arg.net = net;
 609         w->args = &arg;
 610
 611         if (arg.filter.table_id) {
 612                 tb = fib6_get_table(net, arg.filter.table_id);
 613                 if (!tb) {
 614                         if (arg.filter.dump_all_families)
 615                                 goto out;
 616
 617                         NL_SET_ERR_MSG_MOD(cb->extack, "FIB table does not exist");
 618                         return -ENOENT;
 619                 }
 620
 621                 if (!cb->args[0]) {
 622                         res = fib6_dump_table(tb, skb, cb);
 623                         if (!res)
 624                                 cb->args[0] = 1;
 625                 }
 626                 goto out;
 627         }
 628
 629         s_h = cb->args[0];
 630         s_e = cb->args[1];
 631
 632         rcu_read_lock();
 633         for (h = s_h; h < FIB6_TABLE_HASHSZ; h++, s_e = 0) {
 634                 e = 0;
 635                 head = &net->ipv6.fib_table_hash[h];
 636                 hlist_for_each_entry_rcu(tb, head, tb6_hlist) {
 637                         if (e < s_e)
 638                                 goto next;
 639                         res = fib6_dump_table(tb, skb, cb);
 640                         if (res != 0)
 641                                 goto out_unlock;
 642 next:
 643                         e++;
 644                 }
 645         }
 646 out_unlock:
 647         rcu_read_unlock();
 648         cb->args[1] = e;
 649         cb->args[0] = h;
 650 out:
 651         res = res < 0 ? res : skb->len;
 652         if (res <= 0)
 653                 fib6_dump_end(cb);
 654         return res;
 655 }
 656
 657 void fib6_metric_set(struct fib6_info *f6i, int metric, u32 val)
 658 {
 659         if (!f6i)
 660                 return;
 661
 662         if (f6i->fib6_metrics == &dst_default_metrics) {
 663                 struct dst_metrics *p = kzalloc(sizeof(*p), GFP_ATOMIC);
 664
 665                 if (!p)
 666                         return;
 667
 668                 refcount_set(&p->refcnt, 1);
 669                 f6i->fib6_metrics = p;
 670         }
 671
 672         f6i->fib6_metrics->metrics[metric - 1] = val;
 673 }
 674
 675 /*
 676  *      Routing Table
 677  *
 678  *      return the appropriate node for a routing tree "add" operation
 679  *      by either creating and inserting or by returning an existing
 680  *      node.
 681  */
 682
 683 static struct fib6_node *fib6_add_1(struct net *net,
 684                                     struct fib6_table *table,
 685                                     struct fib6_node *root,
 686                                     struct in6_addr *addr, int plen,
 687                                     int offset, int allow_create,
 688                                     int replace_required,
 689                                     struct netlink_ext_ack *extack)
 690 {
 691         struct fib6_node *fn, *in, *ln;
 692         struct fib6_node *pn = NULL;
 693         struct rt6key *key;
 694         int     bit;
 695         __be32  dir = 0;
 696
 697         RT6_TRACE("fib6_add_1\n");
 698
 699         /* insert node in tree */
 700
 701         fn = root;
 702
 703         do {
 704                 struct fib6_info *leaf = rcu_dereference_protected(fn->leaf,
 705                                             lockdep_is_held(&table->tb6_lock));
 706                 key = (struct rt6key *)((u8 *)leaf + offset);
 707
 708                 /*
 709                  *      Prefix match
 710                  */
 711                 if (plen < fn->fn_bit ||
 712                     !ipv6_prefix_equal(&key->addr, addr, fn->fn_bit)) {
 713                         if (!allow_create) {
 714                                 if (replace_required) {
 715                                         NL_SET_ERR_MSG(extack,
 716                                                        "Can not replace route - no match found");
 717                                         pr_warn("Can't replace route, no match found\n");
 718                                         return ERR_PTR(-ENOENT);
 719                                 }
 720                                 pr_warn("NLM_F_CREATE should be set when creating new route\n");
 721                         }
 722                         goto insert_above;
 723                 }
 724
 725                 /*
 726                  *      Exact match ?
 727                  */
 728
 729                 if (plen == fn->fn_bit) {
 730                         /* clean up an intermediate node */
 731                         if (!(fn->fn_flags & RTN_RTINFO)) {
 732                                 RCU_INIT_POINTER(fn->leaf, NULL);
 733                                 fib6_info_release(leaf);
 734                         /* remove null_entry in the root node */
 735                         } else if (fn->fn_flags & RTN_TL_ROOT &&
 736                                    rcu_access_pointer(fn->leaf) ==
 737                                    net->ipv6.fib6_null_entry) {
 738                                 RCU_INIT_POINTER(fn->leaf, NULL);
 739                         }
 740
 741                         return fn;
 742                 }
 743
 744                 /*
 745                  *      We have more bits to go
 746                  */
 747
 748                 /* Try to walk down on tree. */
 749                 dir = addr_bit_set(addr, fn->fn_bit);
 750                 pn = fn;
 751                 fn = dir ?
 752                      rcu_dereference_protected(fn->right,
 753                                         lockdep_is_held(&table->tb6_lock)) :
 754                      rcu_dereference_protected(fn->left,
 755                                         lockdep_is_held(&table->tb6_lock));
 756         } while (fn);
 757
 758         if (!allow_create) {
 759                 /* We should not create new node because
 760                  * NLM_F_REPLACE was specified without NLM_F_CREATE
 761                  * I assume it is safe to require NLM_F_CREATE when
 762                  * REPLACE flag is used! Later we may want to remove the
 763                  * check for replace_required, because according
 764                  * to netlink specification, NLM_F_CREATE
 765                  * MUST be specified if new route is created.
 766                  * That would keep IPv6 consistent with IPv4
 767                  */
 768                 if (replace_required) {
 769                         NL_SET_ERR_MSG(extack,
 770                                        "Can not replace route - no match found");
 771                         pr_warn("Can't replace route, no match found\n");
 772                         return ERR_PTR(-ENOENT);
 773                 }
 774                 pr_warn("NLM_F_CREATE should be set when creating new route\n");
 775         }
 776         /*
 777          *      We walked to the bottom of tree.
 778          *      Create new leaf node without children.
 779          */
 780
 781         ln = node_alloc(net);
 782
 783         if (!ln)
 784                 return ERR_PTR(-ENOMEM);
 785         ln->fn_bit = plen;
 786         RCU_INIT_POINTER(ln->parent, pn);
 787
 788         if (dir)
 789                 rcu_assign_pointer(pn->right, ln);
 790         else
 791                 rcu_assign_pointer(pn->left, ln);
 792
 793         return ln;
 794
 795
 796 insert_above:
 797         /*
 798          * split since we don't have a common prefix anymore or
 799          * we have a less significant route.
 800          * we've to insert an intermediate node on the list
 801          * this new node will point to the one we need to create
 802          * and the current
 803          */
 804
 805         pn = rcu_dereference_protected(fn->parent,
 806                                        lockdep_is_held(&table->tb6_lock));
 807
 808         /* find 1st bit in difference between the 2 addrs.
 809
 810            See comment in __ipv6_addr_diff: bit may be an invalid value,
 811            but if it is >= plen, the value is ignored in any case.
 812          */
 813
 814         bit = __ipv6_addr_diff(addr, &key->addr, sizeof(*addr));
 815
 816         /*
 817          *              (intermediate)[in]
 818          *                /        \
 819          *      (new leaf node)[ln] (old node)[fn]
 820          */
 821         if (plen > bit) {
 822                 in = node_alloc(net);
 823                 ln = node_alloc(net);
 824
 825                 if (!in || !ln) {
 826                         if (in)
 827                                 node_free_immediate(net, in);
 828                         if (ln)
 829                                 node_free_immediate(net, ln);
 830                         return ERR_PTR(-ENOMEM);
 831                 }
 832
 833                 /*
 834                  * new intermediate node.
 835                  * RTN_RTINFO will
 836                  * be off since that an address that chooses one of
 837                  * the branches would not match less specific routes
 838                  * in the other branch
 839                  */
 840
 841                 in->fn_bit = bit;
 842
 843                 RCU_INIT_POINTER(in->parent, pn);
 844                 in->leaf = fn->leaf;
 845                 fib6_info_hold(rcu_dereference_protected(in->leaf,
 846                                 lockdep_is_held(&table->tb6_lock)));
 847
 848                 /* update parent pointer */
 849                 if (dir)
 850                         rcu_assign_pointer(pn->right, in);
 851                 else
 852                         rcu_assign_pointer(pn->left, in);
 853
 854                 ln->fn_bit = plen;
 855
 856                 RCU_INIT_POINTER(ln->parent, in);
 857                 rcu_assign_pointer(fn->parent, in);
 858
 859                 if (addr_bit_set(addr, bit)) {
 860                         rcu_assign_pointer(in->right, ln);
 861                         rcu_assign_pointer(in->left, fn);
 862                 } else {
 863                         rcu_assign_pointer(in->left, ln);
 864                         rcu_assign_pointer(in->right, fn);
 865                 }
 866         } else { /* plen <= bit */
 867
 868                 /*
 869                  *              (new leaf node)[ln]
 870                  *                /        \
 871                  *           (old node)[fn] NULL
 872                  */
 873
 874                 ln = node_alloc(net);
 875
 876                 if (!ln)
 877                         return ERR_PTR(-ENOMEM);
 878
 879                 ln->fn_bit = plen;
 880
 881                 RCU_INIT_POINTER(ln->parent, pn);
 882
 883                 if (addr_bit_set(&key->addr, plen))
 884                         RCU_INIT_POINTER(ln->right, fn);
 885                 else
 886                         RCU_INIT_POINTER(ln->left, fn);
 887
 888                 rcu_assign_pointer(fn->parent, ln);
 889
 890                 if (dir)
 891                         rcu_assign_pointer(pn->right, ln);
 892                 else
 893                         rcu_assign_pointer(pn->left, ln);
 894         }
 895         return ln;
 896 }
 897
 898 static void fib6_drop_pcpu_from(struct fib6_info *f6i,
 899                                 const struct fib6_table *table)
 900 {
 901         int cpu;
 902
 903         /* Make sure rt6_make_pcpu_route() wont add other percpu routes
 904          * while we are cleaning them here.
 905          */
 906         f6i->fib6_destroying = 1;
 907         mb(); /* paired with the cmpxchg() in rt6_make_pcpu_route() */
 908
 909         /* release the reference to this fib entry from
 910          * all of its cached pcpu routes
 911          */
 912         for_each_possible_cpu(cpu) {
 913                 struct rt6_info **ppcpu_rt;
 914                 struct rt6_info *pcpu_rt;
 915
 916                 ppcpu_rt = per_cpu_ptr(f6i->rt6i_pcpu, cpu);
 917                 pcpu_rt = *ppcpu_rt;
 918                 if (pcpu_rt) {
 919                         struct fib6_info *from;
 920
 921                         from = xchg((__force struct fib6_info **)&pcpu_rt->from, NULL);
 922                         fib6_info_release(from);
 923                 }
 924         }
 925 }
 926
 927 static void fib6_purge_rt(struct fib6_info *rt, struct fib6_node *fn,
 928                           struct net *net)
 929 {
 930         struct fib6_table *table = rt->fib6_table;
 931
 932         if (rt->rt6i_pcpu)
 933                 fib6_drop_pcpu_from(rt, table);
 934
 935         if (refcount_read(&rt->fib6_ref) != 1) {
 936                 /* This route is used as dummy address holder in some split
 937                  * nodes. It is not leaked, but it still holds other resources,
 938                  * which must be released in time. So, scan ascendant nodes
 939                  * and replace dummy references to this route with references
 940                  * to still alive ones.
 941                  */
 942                 while (fn) {
 943                         struct fib6_info *leaf = rcu_dereference_protected(fn->leaf,
 944                                             lockdep_is_held(&table->tb6_lock));
 945                         struct fib6_info *new_leaf;
 946                         if (!(fn->fn_flags & RTN_RTINFO) && leaf == rt) {
 947                                 new_leaf = fib6_find_prefix(net, table, fn);
 948                                 fib6_info_hold(new_leaf);
 949
 950                                 rcu_assign_pointer(fn->leaf, new_leaf);
 951                                 fib6_info_release(rt);
 952                         }
 953                         fn = rcu_dereference_protected(fn->parent,
 954                                     lockdep_is_held(&table->tb6_lock));
 955                 }
 956         }
 957 }
 958
 959 /*
 960  *      Insert routing information in a node.
 961  */
 962
 963 static int fib6_add_rt2node(struct fib6_node *fn, struct fib6_info *rt,
 964                             struct nl_info *info,
 965                             struct netlink_ext_ack *extack)
 966 {
 967         struct fib6_info *leaf = rcu_dereference_protected(fn->leaf,
 968                                     lockdep_is_held(&rt->fib6_table->tb6_lock));
 969         struct fib6_info *iter = NULL;
 970         struct fib6_info __rcu **ins;
 971         struct fib6_info __rcu **fallback_ins = NULL;
 972         int replace = (info->nlh &&
 973                        (info->nlh->nlmsg_flags & NLM_F_REPLACE));
 974         int add = (!info->nlh ||
 975                    (info->nlh->nlmsg_flags & NLM_F_CREATE));
 976         int found = 0;
 977         bool rt_can_ecmp = rt6_qualify_for_ecmp(rt);
 978         u16 nlflags = NLM_F_EXCL;
 979         int err;
 980
 981         if (info->nlh && (info->nlh->nlmsg_flags & NLM_F_APPEND))
 982                 nlflags |= NLM_F_APPEND;
 983
 984         ins = &fn->leaf;
 985
 986         for (iter = leaf; iter;
 987              iter = rcu_dereference_protected(iter->fib6_next,
 988                                 lockdep_is_held(&rt->fib6_table->tb6_lock))) {
 989                 /*
 990                  *      Search for duplicates
 991                  */
 992
 993                 if (iter->fib6_metric == rt->fib6_metric) {
 994                         /*
 995                          *      Same priority level
 996                          */
 997                         if (info->nlh &&
 998                             (info->nlh->nlmsg_flags & NLM_F_EXCL))
 999                                 return -EEXIST;
1000
1001                         nlflags &= ~NLM_F_EXCL;
1002                         if (replace) {
1003                                 if (rt_can_ecmp == rt6_qualify_for_ecmp(iter)) {
1004                                         found++;
1005                                         break;
1006                                 }
1007                                 if (rt_can_ecmp)
1008                                         fallback_ins = fallback_ins ?: ins;
1009                                 goto next_iter;
1010                         }
1011
1012                         if (rt6_duplicate_nexthop(iter, rt)) {
1013                                 if (rt->fib6_nsiblings)
1014                                         rt->fib6_nsiblings = 0;
1015                                 if (!(iter->fib6_flags & RTF_EXPIRES))
1016                                         return -EEXIST;
1017                                 if (!(rt->fib6_flags & RTF_EXPIRES))
1018                                         fib6_clean_expires(iter);
1019                                 else
1020                                         fib6_set_expires(iter, rt->expires);
1021
1022                                 if (rt->fib6_pmtu)
1023                                         fib6_metric_set(iter, RTAX_MTU,
1024                                                         rt->fib6_pmtu);
1025                                 return -EEXIST;
1026                         }
1027                         /* If we have the same destination and the same metric,
1028                          * but not the same gateway, then the route we try to
1029                          * add is sibling to this route, increment our counter
1030                          * of siblings, and later we will add our route to the
1031                          * list.
1032                          * Only static routes (which don't have flag
1033                          * RTF_EXPIRES) are used for ECMPv6.
1034                          *
1035                          * To avoid long list, we only had siblings if the
1036                          * route have a gateway.
1037                          */
1038                         if (rt_can_ecmp &&
1039                             rt6_qualify_for_ecmp(iter))
1040                                 rt->fib6_nsiblings++;
1041                 }
1042
1043                 if (iter->fib6_metric > rt->fib6_metric)
1044                         break;
1045
1046 next_iter:
1047                 ins = &iter->fib6_next;
1048         }
1049
1050         if (fallback_ins && !found) {
1051                 /* No ECMP-able route found, replace first non-ECMP one */
1052                 ins = fallback_ins;
1053                 iter = rcu_dereference_protected(*ins,
1054                                     lockdep_is_held(&rt->fib6_table->tb6_lock));
1055                 found++;
1056         }
1057
1058         /* Reset round-robin state, if necessary */
1059         if (ins == &fn->leaf)
1060                 fn->rr_ptr = NULL;
1061
1062         /* Link this route to others same route. */
1063         if (rt->fib6_nsiblings) {
1064                 unsigned int fib6_nsiblings;
1065                 struct fib6_info *sibling, *temp_sibling;
1066
1067                 /* Find the first route that have the same metric */
1068                 sibling = leaf;
1069                 while (sibling) {
1070                         if (sibling->fib6_metric == rt->fib6_metric &&
1071                             rt6_qualify_for_ecmp(sibling)) {
1072                                 list_add_tail(&rt->fib6_siblings,
1073                                               &sibling->fib6_siblings);
1074                                 break;
1075                         }
1076                         sibling = rcu_dereference_protected(sibling->fib6_next,
1077                                     lockdep_is_held(&rt->fib6_table->tb6_lock));
1078                 }
1079                 /* For each sibling in the list, increment the counter of
1080                  * siblings. BUG() if counters does not match, list of siblings
1081                  * is broken!
1082                  */
1083                 fib6_nsiblings = 0;
1084                 list_for_each_entry_safe(sibling, temp_sibling,
1085                                          &rt->fib6_siblings, fib6_siblings) {
1086                         sibling->fib6_nsiblings++;
1087                         BUG_ON(sibling->fib6_nsiblings != rt->fib6_nsiblings);
1088                         fib6_nsiblings++;
1089                 }
1090                 BUG_ON(fib6_nsiblings != rt->fib6_nsiblings);
1091                 rt6_multipath_rebalance(temp_sibling);
1092         }
1093
1094         /*
1095          *      insert node
1096          */
1097         if (!replace) {
1098                 if (!add)
1099                         pr_warn("NLM_F_CREATE should be set when creating new route\n");
1100
1101 add:
1102                 nlflags |= NLM_F_CREATE;
1103
1104                 err = call_fib6_entry_notifiers(info->nl_net,
1105                                                 FIB_EVENT_ENTRY_ADD,
1106                                                 rt, extack);
1107                 if (err)
1108                         return err;
1109
1110                 rcu_assign_pointer(rt->fib6_next, iter);
1111                 fib6_info_hold(rt);
1112                 rcu_assign_pointer(rt->fib6_node, fn);
1113                 rcu_assign_pointer(*ins, rt);
1114                 if (!info->skip_notify)
1115                         inet6_rt_notify(RTM_NEWROUTE, rt, info, nlflags);
1116                 info->nl_net->ipv6.rt6_stats->fib_rt_entries++;
1117
1118                 if (!(fn->fn_flags & RTN_RTINFO)) {
1119                         info->nl_net->ipv6.rt6_stats->fib_route_nodes++;
1120                         fn->fn_flags |= RTN_RTINFO;
1121                 }
1122
1123         } else {
1124                 int nsiblings;
1125
1126                 if (!found) {
1127                         if (add)
1128                                 goto add;
1129                         pr_warn("NLM_F_REPLACE set, but no existing node found!\n");
1130                         return -ENOENT;
1131                 }
1132
1133                 err = call_fib6_entry_notifiers(info->nl_net,
1134                                                 FIB_EVENT_ENTRY_REPLACE,
1135                                                 rt, extack);
1136                 if (err)
1137                         return err;
1138
1139                 fib6_info_hold(rt);
1140                 rcu_assign_pointer(rt->fib6_node, fn);
1141                 rt->fib6_next = iter->fib6_next;
1142                 rcu_assign_pointer(*ins, rt);
1143                 if (!info->skip_notify)
1144                         inet6_rt_notify(RTM_NEWROUTE, rt, info, NLM_F_REPLACE);
1145                 if (!(fn->fn_flags & RTN_RTINFO)) {
1146                         info->nl_net->ipv6.rt6_stats->fib_route_nodes++;
1147                         fn->fn_flags |= RTN_RTINFO;
1148                 }
1149                 nsiblings = iter->fib6_nsiblings;
1150                 iter->fib6_node = NULL;
1151                 fib6_purge_rt(iter, fn, info->nl_net);
1152                 if (rcu_access_pointer(fn->rr_ptr) == iter)
1153                         fn->rr_ptr = NULL;
1154                 fib6_info_release(iter);
1155
1156                 if (nsiblings) {
1157                         /* Replacing an ECMP route, remove all siblings */
1158                         ins = &rt->fib6_next;
1159                         iter = rcu_dereference_protected(*ins,
1160                                     lockdep_is_held(&rt->fib6_table->tb6_lock));
1161                         while (iter) {
1162                                 if (iter->fib6_metric > rt->fib6_metric)
1163                                         break;
1164                                 if (rt6_qualify_for_ecmp(iter)) {
1165                                         *ins = iter->fib6_next;
1166                                         iter->fib6_node = NULL;
1167                                         fib6_purge_rt(iter, fn, info->nl_net);
1168                                         if (rcu_access_pointer(fn->rr_ptr) == iter)
1169                                                 fn->rr_ptr = NULL;
1170                                         fib6_info_release(iter);
1171                                         nsiblings--;
1172                                         info->nl_net->ipv6.rt6_stats->fib_rt_entries--;
1173                                 } else {
1174                                         ins = &iter->fib6_next;
1175                                 }
1176                                 iter = rcu_dereference_protected(*ins,
1177                                         lockdep_is_held(&rt->fib6_table->tb6_lock));
1178                         }
1179                         WARN_ON(nsiblings != 0);
1180                 }
1181         }
1182
1183         return 0;
1184 }
1185
1186 static void fib6_start_gc(struct net *net, struct fib6_info *rt)
1187 {
1188         if (!timer_pending(&net->ipv6.ip6_fib_timer) &&
1189             (rt->fib6_flags & RTF_EXPIRES))
1190                 mod_timer(&net->ipv6.ip6_fib_timer,
1191                           jiffies + net->ipv6.sysctl.ip6_rt_gc_interval);
1192 }
1193
1194 void fib6_force_start_gc(struct net *net)
1195 {
1196         if (!timer_pending(&net->ipv6.ip6_fib_timer))
1197                 mod_timer(&net->ipv6.ip6_fib_timer,
1198                           jiffies + net->ipv6.sysctl.ip6_rt_gc_interval);
1199 }
1200
1201 static void __fib6_update_sernum_upto_root(struct fib6_info *rt,
1202                                            int sernum)
1203 {
1204         struct fib6_node *fn = rcu_dereference_protected(rt->fib6_node,
1205                                 lockdep_is_held(&rt->fib6_table->tb6_lock));
1206
1207         /* paired with smp_rmb() in rt6_get_cookie_safe() */
1208         smp_wmb();
1209         while (fn) {
1210                 fn->fn_sernum = sernum;
1211                 fn = rcu_dereference_protected(fn->parent,
1212                                 lockdep_is_held(&rt->fib6_table->tb6_lock));
1213         }
1214 }
1215
1216 void fib6_update_sernum_upto_root(struct net *net, struct fib6_info *rt)
1217 {
1218         __fib6_update_sernum_upto_root(rt, fib6_new_sernum(net));
1219 }
1220
1221 /*
1222  *      Add routing information to the routing tree.
1223  *      <destination addr>/<source addr>
1224  *      with source addr info in sub-trees
1225  *      Need to own table->tb6_lock
1226  */
1227
1228 int fib6_add(struct fib6_node *root, struct fib6_info *rt,
1229              struct nl_info *info, struct netlink_ext_ack *extack)
1230 {
1231         struct fib6_table *table = rt->fib6_table;
1232         struct fib6_node *fn, *pn = NULL;
1233         int err = -ENOMEM;
1234         int allow_create = 1;
1235         int replace_required = 0;
1236         int sernum = fib6_new_sernum(info->nl_net);
1237
1238         if (info->nlh) {
1239                 if (!(info->nlh->nlmsg_flags & NLM_F_CREATE))
1240                         allow_create = 0;
1241                 if (info->nlh->nlmsg_flags & NLM_F_REPLACE)
1242                         replace_required = 1;
1243         }
1244         if (!allow_create && !replace_required)
1245                 pr_warn("RTM_NEWROUTE with no NLM_F_CREATE or NLM_F_REPLACE\n");
1246
1247         fn = fib6_add_1(info->nl_net, table, root,
1248                         &rt->fib6_dst.addr, rt->fib6_dst.plen,
1249                         offsetof(struct fib6_info, fib6_dst), allow_create,
1250                         replace_required, extack);
1251         if (IS_ERR(fn)) {
1252                 err = PTR_ERR(fn);
1253                 fn = NULL;
1254                 goto out;
1255         }
1256
1257         pn = fn;
1258
1259 #ifdef CONFIG_IPV6_SUBTREES
1260         if (rt->fib6_src.plen) {
1261                 struct fib6_node *sn;
1262
1263                 if (!rcu_access_pointer(fn->subtree)) {
1264                         struct fib6_node *sfn;
1265
1266                         /*
1267                          * Create subtree.
1268                          *
1269                          *              fn[main tree]
1270                          *              |
1271                          *              sfn[subtree root]
1272                          *                 \
1273                          *                  sn[new leaf node]
1274                          */
1275
1276                         /* Create subtree root node */
1277                         sfn = node_alloc(info->nl_net);
1278                         if (!sfn)
1279                                 goto failure;
1280
1281                         fib6_info_hold(info->nl_net->ipv6.fib6_null_entry);
1282                         rcu_assign_pointer(sfn->leaf,
1283                                            info->nl_net->ipv6.fib6_null_entry);
1284                         sfn->fn_flags = RTN_ROOT;
1285
1286                         /* Now add the first leaf node to new subtree */
1287
1288                         sn = fib6_add_1(info->nl_net, table, sfn,
1289                                         &rt->fib6_src.addr, rt->fib6_src.plen,
1290                                         offsetof(struct fib6_info, fib6_src),
1291                                         allow_create, replace_required, extack);
1292
1293                         if (IS_ERR(sn)) {
1294                                 /* If it is failed, discard just allocated
1295                                    root, and then (in failure) stale node
1296                                    in main tree.
1297                                  */
1298                                 node_free_immediate(info->nl_net, sfn);
1299                                 err = PTR_ERR(sn);
1300                                 goto failure;
1301                         }
1302
1303                         /* Now link new subtree to main tree */
1304                         rcu_assign_pointer(sfn->parent, fn);
1305                         rcu_assign_pointer(fn->subtree, sfn);
1306                 } else {
1307                         sn = fib6_add_1(info->nl_net, table, FIB6_SUBTREE(fn),
1308                                         &rt->fib6_src.addr, rt->fib6_src.plen,
1309                                         offsetof(struct fib6_info, fib6_src),
1310                                         allow_create, replace_required, extack);
1311
1312                         if (IS_ERR(sn)) {
1313                                 err = PTR_ERR(sn);
1314                                 goto failure;
1315                         }
1316                 }
1317
1318                 if (!rcu_access_pointer(fn->leaf)) {
1319                         if (fn->fn_flags & RTN_TL_ROOT) {
1320                                 /* put back null_entry for root node */
1321                                 rcu_assign_pointer(fn->leaf,
1322                                             info->nl_net->ipv6.fib6_null_entry);
1323                         } else {
1324                                 fib6_info_hold(rt);
1325                                 rcu_assign_pointer(fn->leaf, rt);
1326                         }
1327                 }
1328                 fn = sn;
1329         }
1330 #endif
1331
1332         err = fib6_add_rt2node(fn, rt, info, extack);
1333         if (!err) {
1334                 __fib6_update_sernum_upto_root(rt, sernum);
1335                 fib6_start_gc(info->nl_net, rt);
1336         }
1337
1338 out:
1339         if (err) {
1340 #ifdef CONFIG_IPV6_SUBTREES
1341                 /*
1342                  * If fib6_add_1 has cleared the old leaf pointer in the
1343                  * super-tree leaf node we have to find a new one for it.
1344                  */
1345                 if (pn != fn) {
1346                         struct fib6_info *pn_leaf =
1347                                 rcu_dereference_protected(pn->leaf,
1348                                     lockdep_is_held(&table->tb6_lock));
1349                         if (pn_leaf == rt) {
1350                                 pn_leaf = NULL;
1351                                 RCU_INIT_POINTER(pn->leaf, NULL);
1352                                 fib6_info_release(rt);
1353                         }
1354                         if (!pn_leaf && !(pn->fn_flags & RTN_RTINFO)) {
1355                                 pn_leaf = fib6_find_prefix(info->nl_net, table,
1356                                                            pn);
1357 #if RT6_DEBUG >= 2
1358                                 if (!pn_leaf) {
1359                                         WARN_ON(!pn_leaf);
1360                                         pn_leaf =
1361                                             info->nl_net->ipv6.fib6_null_entry;
1362                                 }
1363 #endif
1364                                 fib6_info_hold(pn_leaf);
1365                                 rcu_assign_pointer(pn->leaf, pn_leaf);
1366                         }
1367                 }
1368 #endif
1369                 goto failure;
1370         }
1371         return err;
1372
1373 failure:
1374         /* fn->leaf could be NULL and fib6_repair_tree() needs to be called if:
1375          * 1. fn is an intermediate node and we failed to add the new
1376          * route to it in both subtree creation failure and fib6_add_rt2node()
1377          * failure case.
1378          * 2. fn is the root node in the table and we fail to add the first
1379          * default route to it.
1380          */
1381         if (fn &&
1382             (!(fn->fn_flags & (RTN_RTINFO|RTN_ROOT)) ||
1383              (fn->fn_flags & RTN_TL_ROOT &&
1384               !rcu_access_pointer(fn->leaf))))
1385                 fib6_repair_tree(info->nl_net, table, fn);
1386         return err;
1387 }
1388
1389 /*
1390  *      Routing tree lookup
1391  *
1392  */
1393
1394 struct lookup_args {
1395         int                     offset;         /* key offset on fib6_info */
1396         const struct in6_addr   *addr;          /* search key                   */
1397 };
1398
1399 static struct fib6_node *fib6_node_lookup_1(struct fib6_node *root,
1400                                             struct lookup_args *args)
1401 {
1402         struct fib6_node *fn;
1403         __be32 dir;
1404
1405         if (unlikely(args->offset == 0))
1406                 return NULL;
1407
1408         /*
1409          *      Descend on a tree
1410          */
1411
1412         fn = root;
1413
1414         for (;;) {
1415                 struct fib6_node *next;
1416
1417                 dir = addr_bit_set(args->addr, fn->fn_bit);
1418
1419                 next = dir ? rcu_dereference(fn->right) :
1420                              rcu_dereference(fn->left);
1421
1422                 if (next) {
1423                         fn = next;
1424                         continue;
1425                 }
1426                 break;
1427         }
1428
1429         while (fn) {
1430                 struct fib6_node *subtree = FIB6_SUBTREE(fn);
1431
1432                 if (subtree || fn->fn_flags & RTN_RTINFO) {
1433                         struct fib6_info *leaf = rcu_dereference(fn->leaf);
1434                         struct rt6key *key;
1435
1436                         if (!leaf)
1437                                 goto backtrack;
1438
1439                         key = (struct rt6key *) ((u8 *)leaf + args->offset);
1440
1441                         if (ipv6_prefix_equal(&key->addr, args->addr, key->plen)) {
1442 #ifdef CONFIG_IPV6_SUBTREES
1443                                 if (subtree) {
1444                                         struct fib6_node *sfn;
1445                                         sfn = fib6_node_lookup_1(subtree,
1446                                                                  args + 1);
1447                                         if (!sfn)
1448                                                 goto backtrack;
1449                                         fn = sfn;
1450                                 }
1451 #endif
1452                                 if (fn->fn_flags & RTN_RTINFO)
1453                                         return fn;
1454                         }
1455                 }
1456 backtrack:
1457                 if (fn->fn_flags & RTN_ROOT)
1458                         break;
1459
1460                 fn = rcu_dereference(fn->parent);
1461         }
1462
1463         return NULL;
1464 }
1465
1466 /* called with rcu_read_lock() held
1467  */
1468 struct fib6_node *fib6_node_lookup(struct fib6_node *root,
1469                                    const struct in6_addr *daddr,
1470                                    const struct in6_addr *saddr)
1471 {
1472         struct fib6_node *fn;
1473         struct lookup_args args[] = {
1474                 {
1475                         .offset = offsetof(struct fib6_info, fib6_dst),
1476                         .addr = daddr,
1477                 },
1478 #ifdef CONFIG_IPV6_SUBTREES
1479                 {
1480                         .offset = offsetof(struct fib6_info, fib6_src),
1481                         .addr = saddr,
1482                 },
1483 #endif
1484                 {
1485                         .offset = 0,    /* sentinel */
1486                 }
1487         };
1488
1489         fn = fib6_node_lookup_1(root, daddr ? args : args + 1);
1490         if (!fn || fn->fn_flags & RTN_TL_ROOT)
1491                 fn = root;
1492
1493         return fn;
1494 }
1495
1496 /*
1497  *      Get node with specified destination prefix (and source prefix,
1498  *      if subtrees are used)
1499  *      exact_match == true means we try to find fn with exact match of
1500  *      the passed in prefix addr
1501  *      exact_match == false means we try to find fn with longest prefix
1502  *      match of the passed in prefix addr. This is useful for finding fn
1503  *      for cached route as it will be stored in the exception table under
1504  *      the node with longest prefix length.
1505  */
1506
1507
1508 static struct fib6_node *fib6_locate_1(struct fib6_node *root,
1509                                        const struct in6_addr *addr,
1510                                        int plen, int offset,
1511                                        bool exact_match)
1512 {
1513         struct fib6_node *fn, *prev = NULL;
1514
1515         for (fn = root; fn ; ) {
1516                 struct fib6_info *leaf = rcu_dereference(fn->leaf);
1517                 struct rt6key *key;
1518
1519                 /* This node is being deleted */
1520                 if (!leaf) {
1521                         if (plen <= fn->fn_bit)
1522                                 goto out;
1523                         else
1524                                 goto next;
1525                 }
1526
1527                 key = (struct rt6key *)((u8 *)leaf + offset);
1528
1529                 /*
1530                  *      Prefix match
1531                  */
1532                 if (plen < fn->fn_bit ||
1533                     !ipv6_prefix_equal(&key->addr, addr, fn->fn_bit))
1534                         goto out;
1535
1536                 if (plen == fn->fn_bit)
1537                         return fn;
1538
1539                 prev = fn;
1540
1541 next:
1542                 /*
1543                  *      We have more bits to go
1544                  */
1545                 if (addr_bit_set(addr, fn->fn_bit))
1546                         fn = rcu_dereference(fn->right);
1547                 else
1548                         fn = rcu_dereference(fn->left);
1549         }
1550 out:
1551         if (exact_match)
1552                 return NULL;
1553         else
1554                 return prev;
1555 }
1556
1557 struct fib6_node *fib6_locate(struct fib6_node *root,
1558                               const struct in6_addr *daddr, int dst_len,
1559                               const struct in6_addr *saddr, int src_len,
1560                               bool exact_match)
1561 {
1562         struct fib6_node *fn;
1563
1564         fn = fib6_locate_1(root, daddr, dst_len,
1565                            offsetof(struct fib6_info, fib6_dst),
1566                            exact_match);
1567
1568 #ifdef CONFIG_IPV6_SUBTREES
1569         if (src_len) {
1570                 WARN_ON(saddr == NULL);
1571                 if (fn) {
1572                         struct fib6_node *subtree = FIB6_SUBTREE(fn);
1573
1574                         if (subtree) {
1575                                 fn = fib6_locate_1(subtree, saddr, src_len,
1576                                            offsetof(struct fib6_info, fib6_src),
1577                                            exact_match);
1578                         }
1579                 }
1580         }
1581 #endif
1582
1583         if (fn && fn->fn_flags & RTN_RTINFO)
1584                 return fn;
1585
1586         return NULL;
1587 }
1588
1589
1590 /*
1591  *      Deletion
1592  *
1593  */
1594
1595 static struct fib6_info *fib6_find_prefix(struct net *net,
1596                                          struct fib6_table *table,
1597                                          struct fib6_node *fn)
1598 {
1599         struct fib6_node *child_left, *child_right;
1600
1601         if (fn->fn_flags & RTN_ROOT)
1602                 return net->ipv6.fib6_null_entry;
1603
1604         while (fn) {
1605                 child_left = rcu_dereference_protected(fn->left,
1606                                     lockdep_is_held(&table->tb6_lock));
1607                 child_right = rcu_dereference_protected(fn->right,
1608                                     lockdep_is_held(&table->tb6_lock));
1609                 if (child_left)
1610                         return rcu_dereference_protected(child_left->leaf,
1611                                         lockdep_is_held(&table->tb6_lock));
1612                 if (child_right)
1613                         return rcu_dereference_protected(child_right->leaf,
1614                                         lockdep_is_held(&table->tb6_lock));
1615
1616                 fn = FIB6_SUBTREE(fn);
1617         }
1618         return NULL;
1619 }
1620
1621 /*
1622  *      Called to trim the tree of intermediate nodes when possible. "fn"
1623  *      is the node we want to try and remove.
1624  *      Need to own table->tb6_lock
1625  */
1626
1627 static struct fib6_node *fib6_repair_tree(struct net *net,
1628                                           struct fib6_table *table,
1629                                           struct fib6_node *fn)
1630 {
1631         int children;
1632         int nstate;
1633         struct fib6_node *child;
1634         struct fib6_walker *w;
1635         int iter = 0;
1636
1637         /* Set fn->leaf to null_entry for root node. */
1638         if (fn->fn_flags & RTN_TL_ROOT) {
1639                 rcu_assign_pointer(fn->leaf, net->ipv6.fib6_null_entry);
1640                 return fn;
1641         }
1642
1643         for (;;) {
1644                 struct fib6_node *fn_r = rcu_dereference_protected(fn->right,
1645                                             lockdep_is_held(&table->tb6_lock));
1646                 struct fib6_node *fn_l = rcu_dereference_protected(fn->left,
1647                                             lockdep_is_held(&table->tb6_lock));
1648                 struct fib6_node *pn = rcu_dereference_protected(fn->parent,
1649                                             lockdep_is_held(&table->tb6_lock));
1650                 struct fib6_node *pn_r = rcu_dereference_protected(pn->right,
1651                                             lockdep_is_held(&table->tb6_lock));
1652                 struct fib6_node *pn_l = rcu_dereference_protected(pn->left,
1653                                             lockdep_is_held(&table->tb6_lock));
1654                 struct fib6_info *fn_leaf = rcu_dereference_protected(fn->leaf,
1655                                             lockdep_is_held(&table->tb6_lock));
1656                 struct fib6_info *pn_leaf = rcu_dereference_protected(pn->leaf,
1657                                             lockdep_is_held(&table->tb6_lock));
1658                 struct fib6_info *new_fn_leaf;
1659
1660                 RT6_TRACE("fixing tree: plen=%d iter=%d\n", fn->fn_bit, iter);
1661                 iter++;
1662
1663                 WARN_ON(fn->fn_flags & RTN_RTINFO);
1664                 WARN_ON(fn->fn_flags & RTN_TL_ROOT);
1665                 WARN_ON(fn_leaf);
1666
1667                 children = 0;
1668                 child = NULL;
1669                 if (fn_r)
1670                         child = fn_r, children |= 1;
1671                 if (fn_l)
1672                         child = fn_l, children |= 2;
1673
1674                 if (children == 3 || FIB6_SUBTREE(fn)
1675 #ifdef CONFIG_IPV6_SUBTREES
1676                     /* Subtree root (i.e. fn) may have one child */
1677                     || (children && fn->fn_flags & RTN_ROOT)
1678 #endif
1679                     ) {
1680                         new_fn_leaf = fib6_find_prefix(net, table, fn);
1681 #if RT6_DEBUG >= 2
1682                         if (!new_fn_leaf) {
1683                                 WARN_ON(!new_fn_leaf);
1684                                 new_fn_leaf = net->ipv6.fib6_null_entry;
1685                         }
1686 #endif
1687                         fib6_info_hold(new_fn_leaf);
1688                         rcu_assign_pointer(fn->leaf, new_fn_leaf);
1689                         return pn;
1690                 }
1691
1692 #ifdef CONFIG_IPV6_SUBTREES
1693                 if (FIB6_SUBTREE(pn) == fn) {
1694                         WARN_ON(!(fn->fn_flags & RTN_ROOT));
1695                         RCU_INIT_POINTER(pn->subtree, NULL);
1696                         nstate = FWS_L;
1697                 } else {
1698                         WARN_ON(fn->fn_flags & RTN_ROOT);
1699 #endif
1700                         if (pn_r == fn)
1701                                 rcu_assign_pointer(pn->right, child);
1702                         else if (pn_l == fn)
1703                                 rcu_assign_pointer(pn->left, child);
1704 #if RT6_DEBUG >= 2
1705                         else
1706                                 WARN_ON(1);
1707 #endif
1708                         if (child)
1709                                 rcu_assign_pointer(child->parent, pn);
1710                         nstate = FWS_R;
1711 #ifdef CONFIG_IPV6_SUBTREES
1712                 }
1713 #endif
1714
1715                 read_lock(&net->ipv6.fib6_walker_lock);
1716                 FOR_WALKERS(net, w) {
1717                         if (!child) {
1718                                 if (w->node == fn) {
1719                                         RT6_TRACE("W %p adjusted by delnode 1, s=%d/%d\n", w, w->state, nstate);
1720                                         w->node = pn;
1721                                         w->state = nstate;
1722                                 }
1723                         } else {
1724                                 if (w->node == fn) {
1725                                         w->node = child;
1726                                         if (children&2) {
1727                                                 RT6_TRACE("W %p adjusted by delnode 2, s=%d\n", w, w->state);
1728                                                 w->state = w->state >= FWS_R ? FWS_U : FWS_INIT;
1729                                         } else {
1730                                                 RT6_TRACE("W %p adjusted by delnode 2, s=%d\n", w, w->state);
1731                                                 w->state = w->state >= FWS_C ? FWS_U : FWS_INIT;
1732                                         }
1733                                 }
1734                         }
1735                 }
1736                 read_unlock(&net->ipv6.fib6_walker_lock);
1737
1738                 node_free(net, fn);
1739                 if (pn->fn_flags & RTN_RTINFO || FIB6_SUBTREE(pn))
1740                         return pn;
1741
1742                 RCU_INIT_POINTER(pn->leaf, NULL);
1743                 fib6_info_release(pn_leaf);
1744                 fn = pn;
1745         }
1746 }
1747
1748 static void fib6_del_route(struct fib6_table *table, struct fib6_node *fn,
1749                            struct fib6_info __rcu **rtp, struct nl_info *info)
1750 {
1751         struct fib6_walker *w;
1752         struct fib6_info *rt = rcu_dereference_protected(*rtp,
1753                                     lockdep_is_held(&table->tb6_lock));
1754         struct net *net = info->nl_net;
1755
1756         RT6_TRACE("fib6_del_route\n");
1757
1758         /* Unlink it */
1759         *rtp = rt->fib6_next;
1760         rt->fib6_node = NULL;
1761         net->ipv6.rt6_stats->fib_rt_entries--;
1762         net->ipv6.rt6_stats->fib_discarded_routes++;
1763
1764         /* Flush all cached dst in exception table */
1765         rt6_flush_exceptions(rt);
1766
1767         /* Reset round-robin state, if necessary */
1768         if (rcu_access_pointer(fn->rr_ptr) == rt)
1769                 fn->rr_ptr = NULL;
1770
1771         /* Remove this entry from other siblings */
1772         if (rt->fib6_nsiblings) {
1773                 struct fib6_info *sibling, *next_sibling;
1774
1775                 list_for_each_entry_safe(sibling, next_sibling,
1776                                          &rt->fib6_siblings, fib6_siblings)
1777                         sibling->fib6_nsiblings--;
1778                 rt->fib6_nsiblings = 0;
1779                 list_del_init(&rt->fib6_siblings);
1780                 rt6_multipath_rebalance(next_sibling);
1781         }
1782
1783         /* Adjust walkers */
1784         read_lock(&net->ipv6.fib6_walker_lock);
1785         FOR_WALKERS(net, w) {
1786                 if (w->state == FWS_C && w->leaf == rt) {
1787                         RT6_TRACE("walker %p adjusted by delroute\n", w);
1788                         w->leaf = rcu_dereference_protected(rt->fib6_next,
1789                                             lockdep_is_held(&table->tb6_lock));
1790                         if (!w->leaf)
1791                                 w->state = FWS_U;
1792                 }
1793         }
1794         read_unlock(&net->ipv6.fib6_walker_lock);
1795
1796         /* If it was last route, call fib6_repair_tree() to:
1797          * 1. For root node, put back null_entry as how the table was created.
1798          * 2. For other nodes, expunge its radix tree node.
1799          */
1800         if (!rcu_access_pointer(fn->leaf)) {
1801                 if (!(fn->fn_flags & RTN_TL_ROOT)) {
1802                         fn->fn_flags &= ~RTN_RTINFO;
1803                         net->ipv6.rt6_stats->fib_route_nodes--;
1804                 }
1805                 fn = fib6_repair_tree(net, table, fn);
1806         }
1807
1808         fib6_purge_rt(rt, fn, net);
1809
1810         call_fib6_entry_notifiers(net, FIB_EVENT_ENTRY_DEL, rt, NULL);
1811         if (!info->skip_notify)
1812                 inet6_rt_notify(RTM_DELROUTE, rt, info, 0);
1813         fib6_info_release(rt);
1814 }
1815
1816 /* Need to own table->tb6_lock */
1817 int fib6_del(struct fib6_info *rt, struct nl_info *info)
1818 {
1819         struct fib6_node *fn = rcu_dereference_protected(rt->fib6_node,
1820                                     lockdep_is_held(&rt->fib6_table->tb6_lock));
1821         struct fib6_table *table = rt->fib6_table;
1822         struct net *net = info->nl_net;
1823         struct fib6_info __rcu **rtp;
1824         struct fib6_info __rcu **rtp_next;
1825
1826         if (!fn || rt == net->ipv6.fib6_null_entry)
1827                 return -ENOENT;
1828
1829         WARN_ON(!(fn->fn_flags & RTN_RTINFO));
1830
1831         /*
1832          *      Walk the leaf entries looking for ourself
1833          */
1834
1835         for (rtp = &fn->leaf; *rtp; rtp = rtp_next) {
1836                 struct fib6_info *cur = rcu_dereference_protected(*rtp,
1837                                         lockdep_is_held(&table->tb6_lock));
1838                 if (rt == cur) {
1839                         fib6_del_route(table, fn, rtp, info);
1840                         return 0;
1841                 }
1842                 rtp_next = &cur->fib6_next;
1843         }
1844         return -ENOENT;
1845 }
1846
1847 /*
1848  *      Tree traversal function.
1849  *
1850  *      Certainly, it is not interrupt safe.
1851  *      However, it is internally reenterable wrt itself and fib6_add/fib6_del.
1852  *      It means, that we can modify tree during walking
1853  *      and use this function for garbage collection, clone pruning,
1854  *      cleaning tree when a device goes down etc. etc.
1855  *
1856  *      It guarantees that every node will be traversed,
1857  *      and that it will be traversed only once.
1858  *
1859  *      Callback function w->func may return:
1860  *      0 -> continue walking.
1861  *      positive value -> walking is suspended (used by tree dumps,
1862  *      and probably by gc, if it will be split to several slices)
1863  *      negative value -> terminate walking.
1864  *
1865  *      The function itself returns:
1866  *      0   -> walk is complete.
1867  *      >0  -> walk is incomplete (i.e. suspended)
1868  *      <0  -> walk is terminated by an error.
1869  *
1870  *      This function is called with tb6_lock held.
1871  */
1872
1873 static int fib6_walk_continue(struct fib6_walker *w)
1874 {
1875         struct fib6_node *fn, *pn, *left, *right;
1876
1877         /* w->root should always be table->tb6_root */
1878         WARN_ON_ONCE(!(w->root->fn_flags & RTN_TL_ROOT));
1879
1880         for (;;) {
1881                 fn = w->node;
1882                 if (!fn)
1883                         return 0;
1884
1885                 switch (w->state) {
1886 #ifdef CONFIG_IPV6_SUBTREES
1887                 case FWS_S:
1888                         if (FIB6_SUBTREE(fn)) {
1889                                 w->node = FIB6_SUBTREE(fn);
1890                                 continue;
1891                         }
1892                         w->state = FWS_L;
1893 #endif
1894                         /* fall through */
1895                 case FWS_L:
1896                         left = rcu_dereference_protected(fn->left, 1);
1897                         if (left) {
1898                                 w->node = left;
1899                                 w->state = FWS_INIT;
1900                                 continue;
1901                         }
1902                         w->state = FWS_R;
1903                         /* fall through */
1904                 case FWS_R:
1905                         right = rcu_dereference_protected(fn->right, 1);
1906                         if (right) {
1907                                 w->node = right;
1908                                 w->state = FWS_INIT;
1909                                 continue;
1910                         }
1911                         w->state = FWS_C;
1912                         w->leaf = rcu_dereference_protected(fn->leaf, 1);
1913                         /* fall through */
1914                 case FWS_C:
1915                         if (w->leaf && fn->fn_flags & RTN_RTINFO) {
1916                                 int err;
1917
1918                                 if (w->skip) {
1919                                         w->skip--;
1920                                         goto skip;
1921                                 }
1922
1923                                 err = w->func(w);
1924                                 if (err)
1925                                         return err;
1926
1927                                 w->count++;
1928                                 continue;
1929                         }
1930 skip:
1931                         w->state = FWS_U;
1932                         /* fall through */
1933                 case FWS_U:
1934                         if (fn == w->root)
1935                                 return 0;
1936                         pn = rcu_dereference_protected(fn->parent, 1);
1937                         left = rcu_dereference_protected(pn->left, 1);
1938                         right = rcu_dereference_protected(pn->right, 1);
1939                         w->node = pn;
1940 #ifdef CONFIG_IPV6_SUBTREES
1941                         if (FIB6_SUBTREE(pn) == fn) {
1942                                 WARN_ON(!(fn->fn_flags & RTN_ROOT));
1943                                 w->state = FWS_L;
1944                                 continue;
1945                         }
1946 #endif
1947                         if (left == fn) {
1948                                 w->state = FWS_R;
1949                                 continue;
1950                         }
1951                         if (right == fn) {
1952                                 w->state = FWS_C;
1953                                 w->leaf = rcu_dereference_protected(w->node->leaf, 1);
1954                                 continue;
1955                         }
1956 #if RT6_DEBUG >= 2
1957                         WARN_ON(1);
1958 #endif
1959                 }
1960         }
1961 }
1962
1963 static int fib6_walk(struct net *net, struct fib6_walker *w)
1964 {
1965         int res;
1966
1967         w->state = FWS_INIT;
1968         w->node = w->root;
1969
1970         fib6_walker_link(net, w);
1971         res = fib6_walk_continue(w);
1972         if (res <= 0)
1973                 fib6_walker_unlink(net, w);
1974         return res;
1975 }
1976
1977 static int fib6_clean_node(struct fib6_walker *w)
1978 {
1979         int res;
1980         struct fib6_info *rt;
1981         struct fib6_cleaner *c = container_of(w, struct fib6_cleaner, w);
1982         struct nl_info info = {
1983                 .nl_net = c->net,
1984                 .skip_notify = c->skip_notify,
1985         };
1986
1987         if (c->sernum != FIB6_NO_SERNUM_CHANGE &&
1988             w->node->fn_sernum != c->sernum)
1989                 w->node->fn_sernum = c->sernum;
1990
1991         if (!c->func) {
1992                 WARN_ON_ONCE(c->sernum == FIB6_NO_SERNUM_CHANGE);
1993                 w->leaf = NULL;
1994                 return 0;
1995         }
1996
1997         for_each_fib6_walker_rt(w) {
1998                 res = c->func(rt, c->arg);
1999                 if (res == -1) {
2000                         w->leaf = rt;
2001                         res = fib6_del(rt, &info);
2002                         if (res) {
2003 #if RT6_DEBUG >= 2
2004                                 pr_debug("%s: del failed: rt=%p@%p err=%d\n",
2005                                          __func__, rt,
2006                                          rcu_access_pointer(rt->fib6_node),
2007                                          res);
2008 #endif
2009                                 continue;
2010                         }
2011                         return 0;
2012                 } else if (res == -2) {
2013                         if (WARN_ON(!rt->fib6_nsiblings))
2014                                 continue;
2015                         rt = list_last_entry(&rt->fib6_siblings,
2016                                              struct fib6_info, fib6_siblings);
2017                         continue;
2018                 }
2019                 WARN_ON(res != 0);
2020         }
2021         w->leaf = rt;
2022         return 0;
2023 }
2024
2025 /*
2026  *      Convenient frontend to tree walker.
2027  *
2028  *      func is called on each route.
2029  *              It may return -2 -> skip multipath route.
2030  *                            -1 -> delete this route.
2031  *                            0  -> continue walking
2032  */
2033
2034 static void fib6_clean_tree(struct net *net, struct fib6_node *root,
2035                             int (*func)(struct fib6_info *, void *arg),
2036                             int sernum, void *arg, bool skip_notify)
2037 {
2038         struct fib6_cleaner c;
2039
2040         c.w.root = root;
2041         c.w.func = fib6_clean_node;
2042         c.w.count = 0;
2043         c.w.skip = 0;
2044         c.func = func;
2045         c.sernum = sernum;
2046         c.arg = arg;
2047         c.net = net;
2048         c.skip_notify = skip_notify;
2049
2050         fib6_walk(net, &c.w);
2051 }
2052
2053 static void __fib6_clean_all(struct net *net,
2054                              int (*func)(struct fib6_info *, void *),
2055                              int sernum, void *arg, bool skip_notify)
2056 {
2057         struct fib6_table *table;
2058         struct hlist_head *head;
2059         unsigned int h;
2060
2061         rcu_read_lock();
2062         for (h = 0; h < FIB6_TABLE_HASHSZ; h++) {
2063                 head = &net->ipv6.fib_table_hash[h];
2064                 hlist_for_each_entry_rcu(table, head, tb6_hlist) {
2065                         spin_lock_bh(&table->tb6_lock);
2066                         fib6_clean_tree(net, &table->tb6_root,
2067                                         func, sernum, arg, skip_notify);
2068                         spin_unlock_bh(&table->tb6_lock);
2069                 }
2070         }
2071         rcu_read_unlock();
2072 }
2073
2074 void fib6_clean_all(struct net *net, int (*func)(struct fib6_info *, void *),
2075                     void *arg)
2076 {
2077         __fib6_clean_all(net, func, FIB6_NO_SERNUM_CHANGE, arg, false);
2078 }
2079
2080 void fib6_clean_all_skip_notify(struct net *net,
2081                                 int (*func)(struct fib6_info *, void *),
2082                                 void *arg)
2083 {
2084         __fib6_clean_all(net, func, FIB6_NO_SERNUM_CHANGE, arg, true);
2085 }
2086
2087 static void fib6_flush_trees(struct net *net)
2088 {
2089         int new_sernum = fib6_new_sernum(net);
2090
2091         __fib6_clean_all(net, NULL, new_sernum, NULL, false);
2092 }
2093
2094 /*
2095  *      Garbage collection
2096  */
2097
2098 static int fib6_age(struct fib6_info *rt, void *arg)
2099 {
2100         struct fib6_gc_args *gc_args = arg;
2101         unsigned long now = jiffies;
2102
2103         /*
2104          *      check addrconf expiration here.
2105          *      Routes are expired even if they are in use.
2106          */
2107
2108         if (rt->fib6_flags & RTF_EXPIRES && rt->expires) {
2109                 if (time_after(now, rt->expires)) {
2110                         RT6_TRACE("expiring %p\n", rt);
2111                         return -1;
2112                 }
2113                 gc_args->more++;
2114         }
2115
2116         /*      Also age clones in the exception table.
2117          *      Note, that clones are aged out
2118          *      only if they are not in use now.
2119          */
2120         rt6_age_exceptions(rt, gc_args, now);
2121
2122         return 0;
2123 }
2124
2125 void fib6_run_gc(unsigned long expires, struct net *net, bool force)
2126 {
2127         struct fib6_gc_args gc_args;
2128         unsigned long now;
2129
2130         if (force) {
2131                 spin_lock_bh(&net->ipv6.fib6_gc_lock);
2132         } else if (!spin_trylock_bh(&net->ipv6.fib6_gc_lock)) {
2133                 mod_timer(&net->ipv6.ip6_fib_timer, jiffies + HZ);
2134                 return;
2135         }
2136         gc_args.timeout = expires ? (int)expires :
2137                           net->ipv6.sysctl.ip6_rt_gc_interval;
2138         gc_args.more = 0;
2139
2140         fib6_clean_all(net, fib6_age, &gc_args);
2141         now = jiffies;
2142         net->ipv6.ip6_rt_last_gc = now;
2143
2144         if (gc_args.more)
2145                 mod_timer(&net->ipv6.ip6_fib_timer,
2146                           round_jiffies(now
2147                                         + net->ipv6.sysctl.ip6_rt_gc_interval));
2148         else
2149                 del_timer(&net->ipv6.ip6_fib_timer);
2150         spin_unlock_bh(&net->ipv6.fib6_gc_lock);
2151 }
2152
2153 static void fib6_gc_timer_cb(struct timer_list *t)
2154 {
2155         struct net *arg = from_timer(arg, t, ipv6.ip6_fib_timer);
2156
2157         fib6_run_gc(0, arg, true);
2158 }
2159
2160 static int __net_init fib6_net_init(struct net *net)
2161 {
2162         size_t size = sizeof(struct hlist_head) * FIB6_TABLE_HASHSZ;
2163         int err;
2164
2165         err = fib6_notifier_init(net);
2166         if (err)
2167                 return err;
2168
2169         spin_lock_init(&net->ipv6.fib6_gc_lock);
2170         rwlock_init(&net->ipv6.fib6_walker_lock);
2171         INIT_LIST_HEAD(&net->ipv6.fib6_walkers);
2172         timer_setup(&net->ipv6.ip6_fib_timer, fib6_gc_timer_cb, 0);
2173
2174         net->ipv6.rt6_stats = kzalloc(sizeof(*net->ipv6.rt6_stats), GFP_KERNEL);
2175         if (!net->ipv6.rt6_stats)
2176                 goto out_timer;
2177
2178         /* Avoid false sharing : Use at least a full cache line */
2179         size = max_t(size_t, size, L1_CACHE_BYTES);
2180
2181         net->ipv6.fib_table_hash = kzalloc(size, GFP_KERNEL);
2182         if (!net->ipv6.fib_table_hash)
2183                 goto out_rt6_stats;
2184
2185         net->ipv6.fib6_main_tbl = kzalloc(sizeof(*net->ipv6.fib6_main_tbl),
2186                                           GFP_KERNEL);
2187         if (!net->ipv6.fib6_main_tbl)
2188                 goto out_fib_table_hash;
2189
2190         net->ipv6.fib6_main_tbl->tb6_id = RT6_TABLE_MAIN;
2191         rcu_assign_pointer(net->ipv6.fib6_main_tbl->tb6_root.leaf,
2192                            net->ipv6.fib6_null_entry);
2193         net->ipv6.fib6_main_tbl->tb6_root.fn_flags =
2194                 RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
2195         inet_peer_base_init(&net->ipv6.fib6_main_tbl->tb6_peers);
2196
2197 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
2198         net->ipv6.fib6_local_tbl = kzalloc(sizeof(*net->ipv6.fib6_local_tbl),
2199                                            GFP_KERNEL);
2200         if (!net->ipv6.fib6_local_tbl)
2201                 goto out_fib6_main_tbl;
2202         net->ipv6.fib6_local_tbl->tb6_id = RT6_TABLE_LOCAL;
2203         rcu_assign_pointer(net->ipv6.fib6_local_tbl->tb6_root.leaf,
2204                            net->ipv6.fib6_null_entry);
2205         net->ipv6.fib6_local_tbl->tb6_root.fn_flags =
2206                 RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
2207         inet_peer_base_init(&net->ipv6.fib6_local_tbl->tb6_peers);
2208 #endif
2209         fib6_tables_init(net);
2210
2211         return 0;
2212
2213 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
2214 out_fib6_main_tbl:
2215         kfree(net->ipv6.fib6_main_tbl);
2216 #endif
2217 out_fib_table_hash:
2218         kfree(net->ipv6.fib_table_hash);
2219 out_rt6_stats:
2220         kfree(net->ipv6.rt6_stats);
2221 out_timer:
2222         fib6_notifier_exit(net);
2223         return -ENOMEM;
2224 }
2225
2226 static void fib6_net_exit(struct net *net)
2227 {
2228         unsigned int i;
2229
2230         del_timer_sync(&net->ipv6.ip6_fib_timer);
2231
2232         for (i = 0; i < FIB6_TABLE_HASHSZ; i++) {
2233                 struct hlist_head *head = &net->ipv6.fib_table_hash[i];
2234                 struct hlist_node *tmp;
2235                 struct fib6_table *tb;
2236
2237                 hlist_for_each_entry_safe(tb, tmp, head, tb6_hlist) {
2238                         hlist_del(&tb->tb6_hlist);
2239                         fib6_free_table(tb);
2240                 }
2241         }
2242
2243         kfree(net->ipv6.fib_table_hash);
2244         kfree(net->ipv6.rt6_stats);
2245         fib6_notifier_exit(net);
2246 }
2247
2248 static struct pernet_operations fib6_net_ops = {
2249         .init = fib6_net_init,
2250         .exit = fib6_net_exit,
2251 };
2252
2253 int __init fib6_init(void)
2254 {
2255         int ret = -ENOMEM;
2256
2257         fib6_node_kmem = kmem_cache_create("fib6_nodes",
2258                                            sizeof(struct fib6_node),
2259                                            0, SLAB_HWCACHE_ALIGN,
2260                                            NULL);
2261         if (!fib6_node_kmem)
2262                 goto out;
2263
2264         ret = register_pernet_subsys(&fib6_net_ops);
2265         if (ret)
2266                 goto out_kmem_cache_create;
2267
2268         ret = rtnl_register_module(THIS_MODULE, PF_INET6, RTM_GETROUTE, NULL,
2269                                    inet6_dump_fib, 0);
2270         if (ret)
2271                 goto out_unregister_subsys;
2272
2273         __fib6_flush_trees = fib6_flush_trees;
2274 out:
2275         return ret;
2276
2277 out_unregister_subsys:
2278         unregister_pernet_subsys(&fib6_net_ops);
2279 out_kmem_cache_create:
2280         kmem_cache_destroy(fib6_node_kmem);
2281         goto out;
2282 }
2283
2284 void fib6_gc_cleanup(void)
2285 {
2286         unregister_pernet_subsys(&fib6_net_ops);
2287         kmem_cache_destroy(fib6_node_kmem);
2288 }
2289
2290 #ifdef CONFIG_PROC_FS
2291 static int ipv6_route_seq_show(struct seq_file *seq, void *v)
2292 {
2293         struct fib6_info *rt = v;
2294         struct ipv6_route_iter *iter = seq->private;
2295         unsigned int flags = rt->fib6_flags;
2296         const struct net_device *dev;
2297
2298         seq_printf(seq, "%pi6 %02x ", &rt->fib6_dst.addr, rt->fib6_dst.plen);
2299
2300 #ifdef CONFIG_IPV6_SUBTREES
2301         seq_printf(seq, "%pi6 %02x ", &rt->fib6_src.addr, rt->fib6_src.plen);
2302 #else
2303         seq_puts(seq, "00000000000000000000000000000000 00 ");
2304 #endif
2305         if (rt->fib6_nh.fib_nh_gw_family) {
2306                 flags |= RTF_GATEWAY;
2307                 seq_printf(seq, "%pi6", &rt->fib6_nh.fib_nh_gw6);
2308         } else {
2309                 seq_puts(seq, "00000000000000000000000000000000");
2310         }
2311
2312         dev = rt->fib6_nh.fib_nh_dev;
2313         seq_printf(seq, " %08x %08x %08x %08x %8s\n",
2314                    rt->fib6_metric, refcount_read(&rt->fib6_ref), 0,
2315                    flags, dev ? dev->name : "");
2316         iter->w.leaf = NULL;
2317         return 0;
2318 }
2319
2320 static int ipv6_route_yield(struct fib6_walker *w)
2321 {
2322         struct ipv6_route_iter *iter = w->args;
2323
2324         if (!iter->skip)
2325                 return 1;
2326
2327         do {
2328                 iter->w.leaf = rcu_dereference_protected(
2329                                 iter->w.leaf->fib6_next,
2330                                 lockdep_is_held(&iter->tbl->tb6_lock));
2331                 iter->skip--;
2332                 if (!iter->skip && iter->w.leaf)
2333                         return 1;
2334         } while (iter->w.leaf);
2335
2336         return 0;
2337 }
2338
2339 static void ipv6_route_seq_setup_walk(struct ipv6_route_iter *iter,
2340                                       struct net *net)
2341 {
2342         memset(&iter->w, 0, sizeof(iter->w));
2343         iter->w.func = ipv6_route_yield;
2344         iter->w.root = &iter->tbl->tb6_root;
2345         iter->w.state = FWS_INIT;
2346         iter->w.node = iter->w.root;
2347         iter->w.args = iter;
2348         iter->sernum = iter->w.root->fn_sernum;
2349         INIT_LIST_HEAD(&iter->w.lh);
2350         fib6_walker_link(net, &iter->w);
2351 }
2352
2353 static struct fib6_table *ipv6_route_seq_next_table(struct fib6_table *tbl,
2354                                                     struct net *net)
2355 {
2356         unsigned int h;
2357         struct hlist_node *node;
2358
2359         if (tbl) {
2360                 h = (tbl->tb6_id & (FIB6_TABLE_HASHSZ - 1)) + 1;
2361                 node = rcu_dereference_bh(hlist_next_rcu(&tbl->tb6_hlist));
2362         } else {
2363                 h = 0;
2364                 node = NULL;
2365         }
2366
2367         while (!node && h < FIB6_TABLE_HASHSZ) {
2368                 node = rcu_dereference_bh(
2369                         hlist_first_rcu(&net->ipv6.fib_table_hash[h++]));
2370         }
2371         return hlist_entry_safe(node, struct fib6_table, tb6_hlist);
2372 }
2373
2374 static void ipv6_route_check_sernum(struct ipv6_route_iter *iter)
2375 {
2376         if (iter->sernum != iter->w.root->fn_sernum) {
2377                 iter->sernum = iter->w.root->fn_sernum;
2378                 iter->w.state = FWS_INIT;
2379                 iter->w.node = iter->w.root;
2380                 WARN_ON(iter->w.skip);
2381                 iter->w.skip = iter->w.count;
2382         }
2383 }
2384
2385 static void *ipv6_route_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2386 {
2387         int r;
2388         struct fib6_info *n;
2389         struct net *net = seq_file_net(seq);
2390         struct ipv6_route_iter *iter = seq->private;
2391
2392         if (!v)
2393                 goto iter_table;
2394
2395         n = rcu_dereference_bh(((struct fib6_info *)v)->fib6_next);
2396         if (n) {
2397                 ++*pos;
2398                 return n;
2399         }
2400
2401 iter_table:
2402         ipv6_route_check_sernum(iter);
2403         spin_lock_bh(&iter->tbl->tb6_lock);
2404         r = fib6_walk_continue(&iter->w);
2405         spin_unlock_bh(&iter->tbl->tb6_lock);
2406         if (r > 0) {
2407                 if (v)
2408                         ++*pos;
2409                 return iter->w.leaf;
2410         } else if (r < 0) {
2411                 fib6_walker_unlink(net, &iter->w);
2412                 return NULL;
2413         }
2414         fib6_walker_unlink(net, &iter->w);
2415
2416         iter->tbl = ipv6_route_seq_next_table(iter->tbl, net);
2417         if (!iter->tbl)
2418                 return NULL;
2419
2420         ipv6_route_seq_setup_walk(iter, net);
2421         goto iter_table;
2422 }
2423
2424 static void *ipv6_route_seq_start(struct seq_file *seq, loff_t *pos)
2425         __acquires(RCU_BH)
2426 {
2427         struct net *net = seq_file_net(seq);
2428         struct ipv6_route_iter *iter = seq->private;
2429
2430         rcu_read_lock_bh();
2431         iter->tbl = ipv6_route_seq_next_table(NULL, net);
2432         iter->skip = *pos;
2433
2434         if (iter->tbl) {
2435                 ipv6_route_seq_setup_walk(iter, net);
2436                 return ipv6_route_seq_next(seq, NULL, pos);
2437         } else {
2438                 return NULL;
2439         }
2440 }
2441
2442 static bool ipv6_route_iter_active(struct ipv6_route_iter *iter)
2443 {
2444         struct fib6_walker *w = &iter->w;
2445         return w->node && !(w->state == FWS_U && w->node == w->root);
2446 }
2447
2448 static void ipv6_route_seq_stop(struct seq_file *seq, void *v)
2449         __releases(RCU_BH)
2450 {
2451         struct net *net = seq_file_net(seq);
2452         struct ipv6_route_iter *iter = seq->private;
2453
2454         if (ipv6_route_iter_active(iter))
2455                 fib6_walker_unlink(net, &iter->w);
2456
2457         rcu_read_unlock_bh();
2458 }
2459
2460 const struct seq_operations ipv6_route_seq_ops = {
2461         .start  = ipv6_route_seq_start,
2462         .next   = ipv6_route_seq_next,
2463         .stop   = ipv6_route_seq_stop,
2464         .show   = ipv6_route_seq_show
2465 };
2466 #endif /* CONFIG_PROC_FS */