net/ipv6/ip6_fib.c

   1 /*
   2  *      Linux INET6 implementation
   3  *      Forwarding Information Database
   4  *
   5  *      Authors:
   6  *      Pedro Roque             <roque@di.fc.ul.pt>
   7  *
   8  *      This program is free software; you can redistribute it and/or
   9  *      modify it under the terms of the GNU General Public License
  10  *      as published by the Free Software Foundation; either version
  11  *      2 of the License, or (at your option) any later version.
  12  *
  13  *      Changes:
  14  *      Yuji SEKIYA @USAGI:     Support default route on router node;
  15  *                              remove ip6_null_entry from the top of
  16  *                              routing table.
  17  *      Ville Nuorvala:         Fixed routing subtrees.
  18  */
  19
  20 #define pr_fmt(fmt) "IPv6: " fmt
  21
  22 #include <linux/errno.h>
  23 #include <linux/types.h>
  24 #include <linux/net.h>
  25 #include <linux/route.h>
  26 #include <linux/netdevice.h>
  27 #include <linux/in6.h>
  28 #include <linux/init.h>
  29 #include <linux/list.h>
  30 #include <linux/slab.h>
  31
  32 #include <net/ip.h>
  33 #include <net/ipv6.h>
  34 #include <net/ndisc.h>
  35 #include <net/addrconf.h>
  36 #include <net/lwtunnel.h>
  37 #include <net/fib_notifier.h>
  38
  39 #include <net/ip6_fib.h>
  40 #include <net/ip6_route.h>
  41
  42 static struct kmem_cache *fib6_node_kmem __read_mostly;
  43
  44 struct fib6_cleaner {
  45         struct fib6_walker w;
  46         struct net *net;
  47         int (*func)(struct fib6_info *, void *arg);
  48         int sernum;
  49         void *arg;
  50         bool skip_notify;
  51 };
  52
  53 #ifdef CONFIG_IPV6_SUBTREES
  54 #define FWS_INIT FWS_S
  55 #else
  56 #define FWS_INIT FWS_L
  57 #endif
  58
  59 static struct fib6_info *fib6_find_prefix(struct net *net,
  60                                          struct fib6_table *table,
  61                                          struct fib6_node *fn);
  62 static struct fib6_node *fib6_repair_tree(struct net *net,
  63                                           struct fib6_table *table,
  64                                           struct fib6_node *fn);
  65 static int fib6_walk(struct net *net, struct fib6_walker *w);
  66 static int fib6_walk_continue(struct fib6_walker *w);
  67
  68 /*
  69  *      A routing update causes an increase of the serial number on the
  70  *      affected subtree. This allows for cached routes to be asynchronously
  71  *      tested when modifications are made to the destination cache as a
  72  *      result of redirects, path MTU changes, etc.
  73  */
  74
  75 static void fib6_gc_timer_cb(struct timer_list *t);
  76
  77 #define FOR_WALKERS(net, w) \
  78         list_for_each_entry(w, &(net)->ipv6.fib6_walkers, lh)
  79
  80 static void fib6_walker_link(struct net *net, struct fib6_walker *w)
  81 {
  82         write_lock_bh(&net->ipv6.fib6_walker_lock);
  83         list_add(&w->lh, &net->ipv6.fib6_walkers);
  84         write_unlock_bh(&net->ipv6.fib6_walker_lock);
  85 }
  86
  87 static void fib6_walker_unlink(struct net *net, struct fib6_walker *w)
  88 {
  89         write_lock_bh(&net->ipv6.fib6_walker_lock);
  90         list_del(&w->lh);
  91         write_unlock_bh(&net->ipv6.fib6_walker_lock);
  92 }
  93
  94 static int fib6_new_sernum(struct net *net)
  95 {
  96         int new, old;
  97
  98         do {
  99                 old = atomic_read(&net->ipv6.fib6_sernum);
 100                 new = old < INT_MAX ? old + 1 : 1;
 101         } while (atomic_cmpxchg(&net->ipv6.fib6_sernum,
 102                                 old, new) != old);
 103         return new;
 104 }
 105
 106 enum {
 107         FIB6_NO_SERNUM_CHANGE = 0,
 108 };
 109
 110 void fib6_update_sernum(struct net *net, struct fib6_info *f6i)
 111 {
 112         struct fib6_node *fn;
 113
 114         fn = rcu_dereference_protected(f6i->fib6_node,
 115                         lockdep_is_held(&f6i->fib6_table->tb6_lock));
 116         if (fn)
 117                 fn->fn_sernum = fib6_new_sernum(net);
 118 }
 119
 120 /*
 121  *      Auxiliary address test functions for the radix tree.
 122  *
 123  *      These assume a 32bit processor (although it will work on
 124  *      64bit processors)
 125  */
 126
 127 /*
 128  *      test bit
 129  */
 130 #if defined(__LITTLE_ENDIAN)
 131 # define BITOP_BE32_SWIZZLE     (0x1F & ~7)
 132 #else
 133 # define BITOP_BE32_SWIZZLE     0
 134 #endif
 135
 136 static __be32 addr_bit_set(const void *token, int fn_bit)
 137 {
 138         const __be32 *addr = token;
 139         /*
 140          * Here,
 141          *      1 << ((~fn_bit ^ BITOP_BE32_SWIZZLE) & 0x1f)
 142          * is optimized version of
 143          *      htonl(1 << ((~fn_bit)&0x1F))
 144          * See include/asm-generic/bitops/le.h.
 145          */
 146         return (__force __be32)(1 << ((~fn_bit ^ BITOP_BE32_SWIZZLE) & 0x1f)) &
 147                addr[fn_bit >> 5];
 148 }
 149
 150 struct fib6_info *fib6_info_alloc(gfp_t gfp_flags)
 151 {
 152         struct fib6_info *f6i;
 153
 154         f6i = kzalloc(sizeof(*f6i), gfp_flags);
 155         if (!f6i)
 156                 return NULL;
 157
 158         f6i->rt6i_pcpu = alloc_percpu_gfp(struct rt6_info *, gfp_flags);
 159         if (!f6i->rt6i_pcpu) {
 160                 kfree(f6i);
 161                 return NULL;
 162         }
 163
 164         INIT_LIST_HEAD(&f6i->fib6_siblings);
 165         refcount_set(&f6i->fib6_ref, 1);
 166
 167         return f6i;
 168 }
 169
 170 void fib6_info_destroy_rcu(struct rcu_head *head)
 171 {
 172         struct fib6_info *f6i = container_of(head, struct fib6_info, rcu);
 173         struct rt6_exception_bucket *bucket;
 174
 175         WARN_ON(f6i->fib6_node);
 176
 177         bucket = rcu_dereference_protected(f6i->rt6i_exception_bucket, 1);
 178         kfree(bucket);
 179
 180         if (f6i->rt6i_pcpu) {
 181                 int cpu;
 182
 183                 for_each_possible_cpu(cpu) {
 184                         struct rt6_info **ppcpu_rt;
 185                         struct rt6_info *pcpu_rt;
 186
 187                         ppcpu_rt = per_cpu_ptr(f6i->rt6i_pcpu, cpu);
 188                         pcpu_rt = *ppcpu_rt;
 189                         if (pcpu_rt) {
 190                                 dst_dev_put(&pcpu_rt->dst);
 191                                 dst_release(&pcpu_rt->dst);
 192                                 *ppcpu_rt = NULL;
 193                         }
 194                 }
 195
 196                 free_percpu(f6i->rt6i_pcpu);
 197         }
 198
 199         fib6_nh_release(&f6i->fib6_nh);
 200
 201         ip_fib_metrics_put(f6i->fib6_metrics);
 202
 203         kfree(f6i);
 204 }
 205 EXPORT_SYMBOL_GPL(fib6_info_destroy_rcu);
 206
 207 static struct fib6_node *node_alloc(struct net *net)
 208 {
 209         struct fib6_node *fn;
 210
 211         fn = kmem_cache_zalloc(fib6_node_kmem, GFP_ATOMIC);
 212         if (fn)
 213                 net->ipv6.rt6_stats->fib_nodes++;
 214
 215         return fn;
 216 }
 217
 218 static void node_free_immediate(struct net *net, struct fib6_node *fn)
 219 {
 220         kmem_cache_free(fib6_node_kmem, fn);
 221         net->ipv6.rt6_stats->fib_nodes--;
 222 }
 223
 224 static void node_free_rcu(struct rcu_head *head)
 225 {
 226         struct fib6_node *fn = container_of(head, struct fib6_node, rcu);
 227
 228         kmem_cache_free(fib6_node_kmem, fn);
 229 }
 230
 231 static void node_free(struct net *net, struct fib6_node *fn)
 232 {
 233         call_rcu(&fn->rcu, node_free_rcu);
 234         net->ipv6.rt6_stats->fib_nodes--;
 235 }
 236
 237 static void fib6_free_table(struct fib6_table *table)
 238 {
 239         inetpeer_invalidate_tree(&table->tb6_peers);
 240         kfree(table);
 241 }
 242
 243 static void fib6_link_table(struct net *net, struct fib6_table *tb)
 244 {
 245         unsigned int h;
 246
 247         /*
 248          * Initialize table lock at a single place to give lockdep a key,
 249          * tables aren't visible prior to being linked to the list.
 250          */
 251         spin_lock_init(&tb->tb6_lock);
 252         h = tb->tb6_id & (FIB6_TABLE_HASHSZ - 1);
 253
 254         /*
 255          * No protection necessary, this is the only list mutatation
 256          * operation, tables never disappear once they exist.
 257          */
 258         hlist_add_head_rcu(&tb->tb6_hlist, &net->ipv6.fib_table_hash[h]);
 259 }
 260
 261 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
 262
 263 static struct fib6_table *fib6_alloc_table(struct net *net, u32 id)
 264 {
 265         struct fib6_table *table;
 266
 267         table = kzalloc(sizeof(*table), GFP_ATOMIC);
 268         if (table) {
 269                 table->tb6_id = id;
 270                 rcu_assign_pointer(table->tb6_root.leaf,
 271                                    net->ipv6.fib6_null_entry);
 272                 table->tb6_root.fn_flags = RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
 273                 inet_peer_base_init(&table->tb6_peers);
 274         }
 275
 276         return table;
 277 }
 278
 279 struct fib6_table *fib6_new_table(struct net *net, u32 id)
 280 {
 281         struct fib6_table *tb;
 282
 283         if (id == 0)
 284                 id = RT6_TABLE_MAIN;
 285         tb = fib6_get_table(net, id);
 286         if (tb)
 287                 return tb;
 288
 289         tb = fib6_alloc_table(net, id);
 290         if (tb)
 291                 fib6_link_table(net, tb);
 292
 293         return tb;
 294 }
 295 EXPORT_SYMBOL_GPL(fib6_new_table);
 296
 297 struct fib6_table *fib6_get_table(struct net *net, u32 id)
 298 {
 299         struct fib6_table *tb;
 300         struct hlist_head *head;
 301         unsigned int h;
 302
 303         if (id == 0)
 304                 id = RT6_TABLE_MAIN;
 305         h = id & (FIB6_TABLE_HASHSZ - 1);
 306         rcu_read_lock();
 307         head = &net->ipv6.fib_table_hash[h];
 308         hlist_for_each_entry_rcu(tb, head, tb6_hlist) {
 309                 if (tb->tb6_id == id) {
 310                         rcu_read_unlock();
 311                         return tb;
 312                 }
 313         }
 314         rcu_read_unlock();
 315
 316         return NULL;
 317 }
 318 EXPORT_SYMBOL_GPL(fib6_get_table);
 319
 320 static void __net_init fib6_tables_init(struct net *net)
 321 {
 322         fib6_link_table(net, net->ipv6.fib6_main_tbl);
 323         fib6_link_table(net, net->ipv6.fib6_local_tbl);
 324 }
 325 #else
 326
 327 struct fib6_table *fib6_new_table(struct net *net, u32 id)
 328 {
 329         return fib6_get_table(net, id);
 330 }
 331
 332 struct fib6_table *fib6_get_table(struct net *net, u32 id)
 333 {
 334           return net->ipv6.fib6_main_tbl;
 335 }
 336
 337 struct dst_entry *fib6_rule_lookup(struct net *net, struct flowi6 *fl6,
 338                                    const struct sk_buff *skb,
 339                                    int flags, pol_lookup_t lookup)
 340 {
 341         struct rt6_info *rt;
 342
 343         rt = lookup(net, net->ipv6.fib6_main_tbl, fl6, skb, flags);
 344         if (rt->dst.error == -EAGAIN) {
 345                 ip6_rt_put(rt);
 346                 rt = net->ipv6.ip6_null_entry;
 347                 dst_hold(&rt->dst);
 348         }
 349
 350         return &rt->dst;
 351 }
 352
 353 /* called with rcu lock held; no reference taken on fib6_info */
 354 int fib6_lookup(struct net *net, int oif, struct flowi6 *fl6,
 355                 struct fib6_result *res, int flags)
 356 {
 357         return fib6_table_lookup(net, net->ipv6.fib6_main_tbl, oif, fl6,
 358                                  res, flags);
 359 }
 360
 361 static void __net_init fib6_tables_init(struct net *net)
 362 {
 363         fib6_link_table(net, net->ipv6.fib6_main_tbl);
 364 }
 365
 366 #endif
 367
 368 unsigned int fib6_tables_seq_read(struct net *net)
 369 {
 370         unsigned int h, fib_seq = 0;
 371
 372         rcu_read_lock();
 373         for (h = 0; h < FIB6_TABLE_HASHSZ; h++) {
 374                 struct hlist_head *head = &net->ipv6.fib_table_hash[h];
 375                 struct fib6_table *tb;
 376
 377                 hlist_for_each_entry_rcu(tb, head, tb6_hlist)
 378                         fib_seq += tb->fib_seq;
 379         }
 380         rcu_read_unlock();
 381
 382         return fib_seq;
 383 }
 384
 385 static int call_fib6_entry_notifier(struct notifier_block *nb, struct net *net,
 386                                     enum fib_event_type event_type,
 387                                     struct fib6_info *rt)
 388 {
 389         struct fib6_entry_notifier_info info = {
 390                 .rt = rt,
 391         };
 392
 393         return call_fib6_notifier(nb, net, event_type, &info.info);
 394 }
 395
 396 static int call_fib6_entry_notifiers(struct net *net,
 397                                      enum fib_event_type event_type,
 398                                      struct fib6_info *rt,
 399                                      struct netlink_ext_ack *extack)
 400 {
 401         struct fib6_entry_notifier_info info = {
 402                 .info.extack = extack,
 403                 .rt = rt,
 404         };
 405
 406         rt->fib6_table->fib_seq++;
 407         return call_fib6_notifiers(net, event_type, &info.info);
 408 }
 409
 410 struct fib6_dump_arg {
 411         struct net *net;
 412         struct notifier_block *nb;
 413 };
 414
 415 static void fib6_rt_dump(struct fib6_info *rt, struct fib6_dump_arg *arg)
 416 {
 417         if (rt == arg->net->ipv6.fib6_null_entry)
 418                 return;
 419         call_fib6_entry_notifier(arg->nb, arg->net, FIB_EVENT_ENTRY_ADD, rt);
 420 }
 421
 422 static int fib6_node_dump(struct fib6_walker *w)
 423 {
 424         struct fib6_info *rt;
 425
 426         for_each_fib6_walker_rt(w)
 427                 fib6_rt_dump(rt, w->args);
 428         w->leaf = NULL;
 429         return 0;
 430 }
 431
 432 static void fib6_table_dump(struct net *net, struct fib6_table *tb,
 433                             struct fib6_walker *w)
 434 {
 435         w->root = &tb->tb6_root;
 436         spin_lock_bh(&tb->tb6_lock);
 437         fib6_walk(net, w);
 438         spin_unlock_bh(&tb->tb6_lock);
 439 }
 440
 441 /* Called with rcu_read_lock() */
 442 int fib6_tables_dump(struct net *net, struct notifier_block *nb)
 443 {
 444         struct fib6_dump_arg arg;
 445         struct fib6_walker *w;
 446         unsigned int h;
 447
 448         w = kzalloc(sizeof(*w), GFP_ATOMIC);
 449         if (!w)
 450                 return -ENOMEM;
 451
 452         w->func = fib6_node_dump;
 453         arg.net = net;
 454         arg.nb = nb;
 455         w->args = &arg;
 456
 457         for (h = 0; h < FIB6_TABLE_HASHSZ; h++) {
 458                 struct hlist_head *head = &net->ipv6.fib_table_hash[h];
 459                 struct fib6_table *tb;
 460
 461                 hlist_for_each_entry_rcu(tb, head, tb6_hlist)
 462                         fib6_table_dump(net, tb, w);
 463         }
 464
 465         kfree(w);
 466
 467         return 0;
 468 }
 469
 470 static int fib6_dump_node(struct fib6_walker *w)
 471 {
 472         int res;
 473         struct fib6_info *rt;
 474
 475         for_each_fib6_walker_rt(w) {
 476                 res = rt6_dump_route(rt, w->args);
 477                 if (res < 0) {
 478                         /* Frame is full, suspend walking */
 479                         w->leaf = rt;
 480                         return 1;
 481                 }
 482
 483                 /* Multipath routes are dumped in one route with the
 484                  * RTA_MULTIPATH attribute. Jump 'rt' to point to the
 485                  * last sibling of this route (no need to dump the
 486                  * sibling routes again)
 487                  */
 488                 if (rt->fib6_nsiblings)
 489                         rt = list_last_entry(&rt->fib6_siblings,
 490                                              struct fib6_info,
 491                                              fib6_siblings);
 492         }
 493         w->leaf = NULL;
 494         return 0;
 495 }
 496
 497 static void fib6_dump_end(struct netlink_callback *cb)
 498 {
 499         struct net *net = sock_net(cb->skb->sk);
 500         struct fib6_walker *w = (void *)cb->args[2];
 501
 502         if (w) {
 503                 if (cb->args[4]) {
 504                         cb->args[4] = 0;
 505                         fib6_walker_unlink(net, w);
 506                 }
 507                 cb->args[2] = 0;
 508                 kfree(w);
 509         }
 510         cb->done = (void *)cb->args[3];
 511         cb->args[1] = 3;
 512 }
 513
 514 static int fib6_dump_done(struct netlink_callback *cb)
 515 {
 516         fib6_dump_end(cb);
 517         return cb->done ? cb->done(cb) : 0;
 518 }
 519
 520 static int fib6_dump_table(struct fib6_table *table, struct sk_buff *skb,
 521                            struct netlink_callback *cb)
 522 {
 523         struct net *net = sock_net(skb->sk);
 524         struct fib6_walker *w;
 525         int res;
 526
 527         w = (void *)cb->args[2];
 528         w->root = &table->tb6_root;
 529
 530         if (cb->args[4] == 0) {
 531                 w->count = 0;
 532                 w->skip = 0;
 533
 534                 spin_lock_bh(&table->tb6_lock);
 535                 res = fib6_walk(net, w);
 536                 spin_unlock_bh(&table->tb6_lock);
 537                 if (res > 0) {
 538                         cb->args[4] = 1;
 539                         cb->args[5] = w->root->fn_sernum;
 540                 }
 541         } else {
 542                 if (cb->args[5] != w->root->fn_sernum) {
 543                         /* Begin at the root if the tree changed */
 544                         cb->args[5] = w->root->fn_sernum;
 545                         w->state = FWS_INIT;
 546                         w->node = w->root;
 547                         w->skip = w->count;
 548                 } else
 549                         w->skip = 0;
 550
 551                 spin_lock_bh(&table->tb6_lock);
 552                 res = fib6_walk_continue(w);
 553                 spin_unlock_bh(&table->tb6_lock);
 554                 if (res <= 0) {
 555                         fib6_walker_unlink(net, w);
 556                         cb->args[4] = 0;
 557                 }
 558         }
 559
 560         return res;
 561 }
 562
 563 static int inet6_dump_fib(struct sk_buff *skb, struct netlink_callback *cb)
 564 {
 565         const struct nlmsghdr *nlh = cb->nlh;
 566         struct net *net = sock_net(skb->sk);
 567         struct rt6_rtnl_dump_arg arg = {};
 568         unsigned int h, s_h;
 569         unsigned int e = 0, s_e;
 570         struct fib6_walker *w;
 571         struct fib6_table *tb;
 572         struct hlist_head *head;
 573         int res = 0;
 574
 575         if (cb->strict_check) {
 576                 int err;
 577
 578                 err = ip_valid_fib_dump_req(net, nlh, &arg.filter, cb);
 579                 if (err < 0)
 580                         return err;
 581         } else if (nlmsg_len(nlh) >= sizeof(struct rtmsg)) {
 582                 struct rtmsg *rtm = nlmsg_data(nlh);
 583
 584                 arg.filter.flags = rtm->rtm_flags & (RTM_F_PREFIX|RTM_F_CLONED);
 585         }
 586
 587         /* fib entries are never clones */
 588         if (arg.filter.flags & RTM_F_CLONED)
 589                 goto out;
 590
 591         w = (void *)cb->args[2];
 592         if (!w) {
 593                 /* New dump:
 594                  *
 595                  * 1. hook callback destructor.
 596                  */
 597                 cb->args[3] = (long)cb->done;
 598                 cb->done = fib6_dump_done;
 599
 600                 /*
 601                  * 2. allocate and initialize walker.
 602                  */
 603                 w = kzalloc(sizeof(*w), GFP_ATOMIC);
 604                 if (!w)
 605                         return -ENOMEM;
 606                 w->func = fib6_dump_node;
 607                 cb->args[2] = (long)w;
 608         }
 609
 610         arg.skb = skb;
 611         arg.cb = cb;
 612         arg.net = net;
 613         w->args = &arg;
 614
 615         if (arg.filter.table_id) {
 616                 tb = fib6_get_table(net, arg.filter.table_id);
 617                 if (!tb) {
 618                         if (arg.filter.dump_all_families)
 619                                 goto out;
 620
 621                         NL_SET_ERR_MSG_MOD(cb->extack, "FIB table does not exist");
 622                         return -ENOENT;
 623                 }
 624
 625                 if (!cb->args[0]) {
 626                         res = fib6_dump_table(tb, skb, cb);
 627                         if (!res)
 628                                 cb->args[0] = 1;
 629                 }
 630                 goto out;
 631         }
 632
 633         s_h = cb->args[0];
 634         s_e = cb->args[1];
 635
 636         rcu_read_lock();
 637         for (h = s_h; h < FIB6_TABLE_HASHSZ; h++, s_e = 0) {
 638                 e = 0;
 639                 head = &net->ipv6.fib_table_hash[h];
 640                 hlist_for_each_entry_rcu(tb, head, tb6_hlist) {
 641                         if (e < s_e)
 642                                 goto next;
 643                         res = fib6_dump_table(tb, skb, cb);
 644                         if (res != 0)
 645                                 goto out_unlock;
 646 next:
 647                         e++;
 648                 }
 649         }
 650 out_unlock:
 651         rcu_read_unlock();
 652         cb->args[1] = e;
 653         cb->args[0] = h;
 654 out:
 655         res = res < 0 ? res : skb->len;
 656         if (res <= 0)
 657                 fib6_dump_end(cb);
 658         return res;
 659 }
 660
 661 void fib6_metric_set(struct fib6_info *f6i, int metric, u32 val)
 662 {
 663         if (!f6i)
 664                 return;
 665
 666         if (f6i->fib6_metrics == &dst_default_metrics) {
 667                 struct dst_metrics *p = kzalloc(sizeof(*p), GFP_ATOMIC);
 668
 669                 if (!p)
 670                         return;
 671
 672                 refcount_set(&p->refcnt, 1);
 673                 f6i->fib6_metrics = p;
 674         }
 675
 676         f6i->fib6_metrics->metrics[metric - 1] = val;
 677 }
 678
 679 /*
 680  *      Routing Table
 681  *
 682  *      return the appropriate node for a routing tree "add" operation
 683  *      by either creating and inserting or by returning an existing
 684  *      node.
 685  */
 686
 687 static struct fib6_node *fib6_add_1(struct net *net,
 688                                     struct fib6_table *table,
 689                                     struct fib6_node *root,
 690                                     struct in6_addr *addr, int plen,
 691                                     int offset, int allow_create,
 692                                     int replace_required,
 693                                     struct netlink_ext_ack *extack)
 694 {
 695         struct fib6_node *fn, *in, *ln;
 696         struct fib6_node *pn = NULL;
 697         struct rt6key *key;
 698         int     bit;
 699         __be32  dir = 0;
 700
 701         RT6_TRACE("fib6_add_1\n");
 702
 703         /* insert node in tree */
 704
 705         fn = root;
 706
 707         do {
 708                 struct fib6_info *leaf = rcu_dereference_protected(fn->leaf,
 709                                             lockdep_is_held(&table->tb6_lock));
 710                 key = (struct rt6key *)((u8 *)leaf + offset);
 711
 712                 /*
 713                  *      Prefix match
 714                  */
 715                 if (plen < fn->fn_bit ||
 716                     !ipv6_prefix_equal(&key->addr, addr, fn->fn_bit)) {
 717                         if (!allow_create) {
 718                                 if (replace_required) {
 719                                         NL_SET_ERR_MSG(extack,
 720                                                        "Can not replace route - no match found");
 721                                         pr_warn("Can't replace route, no match found\n");
 722                                         return ERR_PTR(-ENOENT);
 723                                 }
 724                                 pr_warn("NLM_F_CREATE should be set when creating new route\n");
 725                         }
 726                         goto insert_above;
 727                 }
 728
 729                 /*
 730                  *      Exact match ?
 731                  */
 732
 733                 if (plen == fn->fn_bit) {
 734                         /* clean up an intermediate node */
 735                         if (!(fn->fn_flags & RTN_RTINFO)) {
 736                                 RCU_INIT_POINTER(fn->leaf, NULL);
 737                                 fib6_info_release(leaf);
 738                         /* remove null_entry in the root node */
 739                         } else if (fn->fn_flags & RTN_TL_ROOT &&
 740                                    rcu_access_pointer(fn->leaf) ==
 741                                    net->ipv6.fib6_null_entry) {
 742                                 RCU_INIT_POINTER(fn->leaf, NULL);
 743                         }
 744
 745                         return fn;
 746                 }
 747
 748                 /*
 749                  *      We have more bits to go
 750                  */
 751
 752                 /* Try to walk down on tree. */
 753                 dir = addr_bit_set(addr, fn->fn_bit);
 754                 pn = fn;
 755                 fn = dir ?
 756                      rcu_dereference_protected(fn->right,
 757                                         lockdep_is_held(&table->tb6_lock)) :
 758                      rcu_dereference_protected(fn->left,
 759                                         lockdep_is_held(&table->tb6_lock));
 760         } while (fn);
 761
 762         if (!allow_create) {
 763                 /* We should not create new node because
 764                  * NLM_F_REPLACE was specified without NLM_F_CREATE
 765                  * I assume it is safe to require NLM_F_CREATE when
 766                  * REPLACE flag is used! Later we may want to remove the
 767                  * check for replace_required, because according
 768                  * to netlink specification, NLM_F_CREATE
 769                  * MUST be specified if new route is created.
 770                  * That would keep IPv6 consistent with IPv4
 771                  */
 772                 if (replace_required) {
 773                         NL_SET_ERR_MSG(extack,
 774                                        "Can not replace route - no match found");
 775                         pr_warn("Can't replace route, no match found\n");
 776                         return ERR_PTR(-ENOENT);
 777                 }
 778                 pr_warn("NLM_F_CREATE should be set when creating new route\n");
 779         }
 780         /*
 781          *      We walked to the bottom of tree.
 782          *      Create new leaf node without children.
 783          */
 784
 785         ln = node_alloc(net);
 786
 787         if (!ln)
 788                 return ERR_PTR(-ENOMEM);
 789         ln->fn_bit = plen;
 790         RCU_INIT_POINTER(ln->parent, pn);
 791
 792         if (dir)
 793                 rcu_assign_pointer(pn->right, ln);
 794         else
 795                 rcu_assign_pointer(pn->left, ln);
 796
 797         return ln;
 798
 799
 800 insert_above:
 801         /*
 802          * split since we don't have a common prefix anymore or
 803          * we have a less significant route.
 804          * we've to insert an intermediate node on the list
 805          * this new node will point to the one we need to create
 806          * and the current
 807          */
 808
 809         pn = rcu_dereference_protected(fn->parent,
 810                                        lockdep_is_held(&table->tb6_lock));
 811
 812         /* find 1st bit in difference between the 2 addrs.
 813
 814            See comment in __ipv6_addr_diff: bit may be an invalid value,
 815            but if it is >= plen, the value is ignored in any case.
 816          */
 817
 818         bit = __ipv6_addr_diff(addr, &key->addr, sizeof(*addr));
 819
 820         /*
 821          *              (intermediate)[in]
 822          *                /        \
 823          *      (new leaf node)[ln] (old node)[fn]
 824          */
 825         if (plen > bit) {
 826                 in = node_alloc(net);
 827                 ln = node_alloc(net);
 828
 829                 if (!in || !ln) {
 830                         if (in)
 831                                 node_free_immediate(net, in);
 832                         if (ln)
 833                                 node_free_immediate(net, ln);
 834                         return ERR_PTR(-ENOMEM);
 835                 }
 836
 837                 /*
 838                  * new intermediate node.
 839                  * RTN_RTINFO will
 840                  * be off since that an address that chooses one of
 841                  * the branches would not match less specific routes
 842                  * in the other branch
 843                  */
 844
 845                 in->fn_bit = bit;
 846
 847                 RCU_INIT_POINTER(in->parent, pn);
 848                 in->leaf = fn->leaf;
 849                 fib6_info_hold(rcu_dereference_protected(in->leaf,
 850                                 lockdep_is_held(&table->tb6_lock)));
 851
 852                 /* update parent pointer */
 853                 if (dir)
 854                         rcu_assign_pointer(pn->right, in);
 855                 else
 856                         rcu_assign_pointer(pn->left, in);
 857
 858                 ln->fn_bit = plen;
 859
 860                 RCU_INIT_POINTER(ln->parent, in);
 861                 rcu_assign_pointer(fn->parent, in);
 862
 863                 if (addr_bit_set(addr, bit)) {
 864                         rcu_assign_pointer(in->right, ln);
 865                         rcu_assign_pointer(in->left, fn);
 866                 } else {
 867                         rcu_assign_pointer(in->left, ln);
 868                         rcu_assign_pointer(in->right, fn);
 869                 }
 870         } else { /* plen <= bit */
 871
 872                 /*
 873                  *              (new leaf node)[ln]
 874                  *                /        \
 875                  *           (old node)[fn] NULL
 876                  */
 877
 878                 ln = node_alloc(net);
 879
 880                 if (!ln)
 881                         return ERR_PTR(-ENOMEM);
 882
 883                 ln->fn_bit = plen;
 884
 885                 RCU_INIT_POINTER(ln->parent, pn);
 886
 887                 if (addr_bit_set(&key->addr, plen))
 888                         RCU_INIT_POINTER(ln->right, fn);
 889                 else
 890                         RCU_INIT_POINTER(ln->left, fn);
 891
 892                 rcu_assign_pointer(fn->parent, ln);
 893
 894                 if (dir)
 895                         rcu_assign_pointer(pn->right, ln);
 896                 else
 897                         rcu_assign_pointer(pn->left, ln);
 898         }
 899         return ln;
 900 }
 901
 902 static void fib6_drop_pcpu_from(struct fib6_info *f6i,
 903                                 const struct fib6_table *table)
 904 {
 905         int cpu;
 906
 907         /* Make sure rt6_make_pcpu_route() wont add other percpu routes
 908          * while we are cleaning them here.
 909          */
 910         f6i->fib6_destroying = 1;
 911         mb(); /* paired with the cmpxchg() in rt6_make_pcpu_route() */
 912
 913         /* release the reference to this fib entry from
 914          * all of its cached pcpu routes
 915          */
 916         for_each_possible_cpu(cpu) {
 917                 struct rt6_info **ppcpu_rt;
 918                 struct rt6_info *pcpu_rt;
 919
 920                 ppcpu_rt = per_cpu_ptr(f6i->rt6i_pcpu, cpu);
 921                 pcpu_rt = *ppcpu_rt;
 922                 if (pcpu_rt) {
 923                         struct fib6_info *from;
 924
 925                         from = xchg((__force struct fib6_info **)&pcpu_rt->from, NULL);
 926                         fib6_info_release(from);
 927                 }
 928         }
 929 }
 930
 931 static void fib6_purge_rt(struct fib6_info *rt, struct fib6_node *fn,
 932                           struct net *net)
 933 {
 934         struct fib6_table *table = rt->fib6_table;
 935
 936         if (rt->rt6i_pcpu)
 937                 fib6_drop_pcpu_from(rt, table);
 938
 939         if (refcount_read(&rt->fib6_ref) != 1) {
 940                 /* This route is used as dummy address holder in some split
 941                  * nodes. It is not leaked, but it still holds other resources,
 942                  * which must be released in time. So, scan ascendant nodes
 943                  * and replace dummy references to this route with references
 944                  * to still alive ones.
 945                  */
 946                 while (fn) {
 947                         struct fib6_info *leaf = rcu_dereference_protected(fn->leaf,
 948                                             lockdep_is_held(&table->tb6_lock));
 949                         struct fib6_info *new_leaf;
 950                         if (!(fn->fn_flags & RTN_RTINFO) && leaf == rt) {
 951                                 new_leaf = fib6_find_prefix(net, table, fn);
 952                                 fib6_info_hold(new_leaf);
 953
 954                                 rcu_assign_pointer(fn->leaf, new_leaf);
 955                                 fib6_info_release(rt);
 956                         }
 957                         fn = rcu_dereference_protected(fn->parent,
 958                                     lockdep_is_held(&table->tb6_lock));
 959                 }
 960         }
 961 }
 962
 963 /*
 964  *      Insert routing information in a node.
 965  */
 966
 967 static int fib6_add_rt2node(struct fib6_node *fn, struct fib6_info *rt,
 968                             struct nl_info *info,
 969                             struct netlink_ext_ack *extack)
 970 {
 971         struct fib6_info *leaf = rcu_dereference_protected(fn->leaf,
 972                                     lockdep_is_held(&rt->fib6_table->tb6_lock));
 973         struct fib6_info *iter = NULL;
 974         struct fib6_info __rcu **ins;
 975         struct fib6_info __rcu **fallback_ins = NULL;
 976         int replace = (info->nlh &&
 977                        (info->nlh->nlmsg_flags & NLM_F_REPLACE));
 978         int add = (!info->nlh ||
 979                    (info->nlh->nlmsg_flags & NLM_F_CREATE));
 980         int found = 0;
 981         bool rt_can_ecmp = rt6_qualify_for_ecmp(rt);
 982         u16 nlflags = NLM_F_EXCL;
 983         int err;
 984
 985         if (info->nlh && (info->nlh->nlmsg_flags & NLM_F_APPEND))
 986                 nlflags |= NLM_F_APPEND;
 987
 988         ins = &fn->leaf;
 989
 990         for (iter = leaf; iter;
 991              iter = rcu_dereference_protected(iter->fib6_next,
 992                                 lockdep_is_held(&rt->fib6_table->tb6_lock))) {
 993                 /*
 994                  *      Search for duplicates
 995                  */
 996
 997                 if (iter->fib6_metric == rt->fib6_metric) {
 998                         /*
 999                          *      Same priority level
1000                          */
1001                         if (info->nlh &&
1002                             (info->nlh->nlmsg_flags & NLM_F_EXCL))
1003                                 return -EEXIST;
1004
1005                         nlflags &= ~NLM_F_EXCL;
1006                         if (replace) {
1007                                 if (rt_can_ecmp == rt6_qualify_for_ecmp(iter)) {
1008                                         found++;
1009                                         break;
1010                                 }
1011                                 if (rt_can_ecmp)
1012                                         fallback_ins = fallback_ins ?: ins;
1013                                 goto next_iter;
1014                         }
1015
1016                         if (rt6_duplicate_nexthop(iter, rt)) {
1017                                 if (rt->fib6_nsiblings)
1018                                         rt->fib6_nsiblings = 0;
1019                                 if (!(iter->fib6_flags & RTF_EXPIRES))
1020                                         return -EEXIST;
1021                                 if (!(rt->fib6_flags & RTF_EXPIRES))
1022                                         fib6_clean_expires(iter);
1023                                 else
1024                                         fib6_set_expires(iter, rt->expires);
1025
1026                                 if (rt->fib6_pmtu)
1027                                         fib6_metric_set(iter, RTAX_MTU,
1028                                                         rt->fib6_pmtu);
1029                                 return -EEXIST;
1030                         }
1031                         /* If we have the same destination and the same metric,
1032                          * but not the same gateway, then the route we try to
1033                          * add is sibling to this route, increment our counter
1034                          * of siblings, and later we will add our route to the
1035                          * list.
1036                          * Only static routes (which don't have flag
1037                          * RTF_EXPIRES) are used for ECMPv6.
1038                          *
1039                          * To avoid long list, we only had siblings if the
1040                          * route have a gateway.
1041                          */
1042                         if (rt_can_ecmp &&
1043                             rt6_qualify_for_ecmp(iter))
1044                                 rt->fib6_nsiblings++;
1045                 }
1046
1047                 if (iter->fib6_metric > rt->fib6_metric)
1048                         break;
1049
1050 next_iter:
1051                 ins = &iter->fib6_next;
1052         }
1053
1054         if (fallback_ins && !found) {
1055                 /* No ECMP-able route found, replace first non-ECMP one */
1056                 ins = fallback_ins;
1057                 iter = rcu_dereference_protected(*ins,
1058                                     lockdep_is_held(&rt->fib6_table->tb6_lock));
1059                 found++;
1060         }
1061
1062         /* Reset round-robin state, if necessary */
1063         if (ins == &fn->leaf)
1064                 fn->rr_ptr = NULL;
1065
1066         /* Link this route to others same route. */
1067         if (rt->fib6_nsiblings) {
1068                 unsigned int fib6_nsiblings;
1069                 struct fib6_info *sibling, *temp_sibling;
1070
1071                 /* Find the first route that have the same metric */
1072                 sibling = leaf;
1073                 while (sibling) {
1074                         if (sibling->fib6_metric == rt->fib6_metric &&
1075                             rt6_qualify_for_ecmp(sibling)) {
1076                                 list_add_tail(&rt->fib6_siblings,
1077                                               &sibling->fib6_siblings);
1078                                 break;
1079                         }
1080                         sibling = rcu_dereference_protected(sibling->fib6_next,
1081                                     lockdep_is_held(&rt->fib6_table->tb6_lock));
1082                 }
1083                 /* For each sibling in the list, increment the counter of
1084                  * siblings. BUG() if counters does not match, list of siblings
1085                  * is broken!
1086                  */
1087                 fib6_nsiblings = 0;
1088                 list_for_each_entry_safe(sibling, temp_sibling,
1089                                          &rt->fib6_siblings, fib6_siblings) {
1090                         sibling->fib6_nsiblings++;
1091                         BUG_ON(sibling->fib6_nsiblings != rt->fib6_nsiblings);
1092                         fib6_nsiblings++;
1093                 }
1094                 BUG_ON(fib6_nsiblings != rt->fib6_nsiblings);
1095                 rt6_multipath_rebalance(temp_sibling);
1096         }
1097
1098         /*
1099          *      insert node
1100          */
1101         if (!replace) {
1102                 if (!add)
1103                         pr_warn("NLM_F_CREATE should be set when creating new route\n");
1104
1105 add:
1106                 nlflags |= NLM_F_CREATE;
1107
1108                 err = call_fib6_entry_notifiers(info->nl_net,
1109                                                 FIB_EVENT_ENTRY_ADD,
1110                                                 rt, extack);
1111                 if (err)
1112                         return err;
1113
1114                 rcu_assign_pointer(rt->fib6_next, iter);
1115                 fib6_info_hold(rt);
1116                 rcu_assign_pointer(rt->fib6_node, fn);
1117                 rcu_assign_pointer(*ins, rt);
1118                 if (!info->skip_notify)
1119                         inet6_rt_notify(RTM_NEWROUTE, rt, info, nlflags);
1120                 info->nl_net->ipv6.rt6_stats->fib_rt_entries++;
1121
1122                 if (!(fn->fn_flags & RTN_RTINFO)) {
1123                         info->nl_net->ipv6.rt6_stats->fib_route_nodes++;
1124                         fn->fn_flags |= RTN_RTINFO;
1125                 }
1126
1127         } else {
1128                 int nsiblings;
1129
1130                 if (!found) {
1131                         if (add)
1132                                 goto add;
1133                         pr_warn("NLM_F_REPLACE set, but no existing node found!\n");
1134                         return -ENOENT;
1135                 }
1136
1137                 err = call_fib6_entry_notifiers(info->nl_net,
1138                                                 FIB_EVENT_ENTRY_REPLACE,
1139                                                 rt, extack);
1140                 if (err)
1141                         return err;
1142
1143                 fib6_info_hold(rt);
1144                 rcu_assign_pointer(rt->fib6_node, fn);
1145                 rt->fib6_next = iter->fib6_next;
1146                 rcu_assign_pointer(*ins, rt);
1147                 if (!info->skip_notify)
1148                         inet6_rt_notify(RTM_NEWROUTE, rt, info, NLM_F_REPLACE);
1149                 if (!(fn->fn_flags & RTN_RTINFO)) {
1150                         info->nl_net->ipv6.rt6_stats->fib_route_nodes++;
1151                         fn->fn_flags |= RTN_RTINFO;
1152                 }
1153                 nsiblings = iter->fib6_nsiblings;
1154                 iter->fib6_node = NULL;
1155                 fib6_purge_rt(iter, fn, info->nl_net);
1156                 if (rcu_access_pointer(fn->rr_ptr) == iter)
1157                         fn->rr_ptr = NULL;
1158                 fib6_info_release(iter);
1159
1160                 if (nsiblings) {
1161                         /* Replacing an ECMP route, remove all siblings */
1162                         ins = &rt->fib6_next;
1163                         iter = rcu_dereference_protected(*ins,
1164                                     lockdep_is_held(&rt->fib6_table->tb6_lock));
1165                         while (iter) {
1166                                 if (iter->fib6_metric > rt->fib6_metric)
1167                                         break;
1168                                 if (rt6_qualify_for_ecmp(iter)) {
1169                                         *ins = iter->fib6_next;
1170                                         iter->fib6_node = NULL;
1171                                         fib6_purge_rt(iter, fn, info->nl_net);
1172                                         if (rcu_access_pointer(fn->rr_ptr) == iter)
1173                                                 fn->rr_ptr = NULL;
1174                                         fib6_info_release(iter);
1175                                         nsiblings--;
1176                                         info->nl_net->ipv6.rt6_stats->fib_rt_entries--;
1177                                 } else {
1178                                         ins = &iter->fib6_next;
1179                                 }
1180                                 iter = rcu_dereference_protected(*ins,
1181                                         lockdep_is_held(&rt->fib6_table->tb6_lock));
1182                         }
1183                         WARN_ON(nsiblings != 0);
1184                 }
1185         }
1186
1187         return 0;
1188 }
1189
1190 static void fib6_start_gc(struct net *net, struct fib6_info *rt)
1191 {
1192         if (!timer_pending(&net->ipv6.ip6_fib_timer) &&
1193             (rt->fib6_flags & RTF_EXPIRES))
1194                 mod_timer(&net->ipv6.ip6_fib_timer,
1195                           jiffies + net->ipv6.sysctl.ip6_rt_gc_interval);
1196 }
1197
1198 void fib6_force_start_gc(struct net *net)
1199 {
1200         if (!timer_pending(&net->ipv6.ip6_fib_timer))
1201                 mod_timer(&net->ipv6.ip6_fib_timer,
1202                           jiffies + net->ipv6.sysctl.ip6_rt_gc_interval);
1203 }
1204
1205 static void __fib6_update_sernum_upto_root(struct fib6_info *rt,
1206                                            int sernum)
1207 {
1208         struct fib6_node *fn = rcu_dereference_protected(rt->fib6_node,
1209                                 lockdep_is_held(&rt->fib6_table->tb6_lock));
1210
1211         /* paired with smp_rmb() in rt6_get_cookie_safe() */
1212         smp_wmb();
1213         while (fn) {
1214                 fn->fn_sernum = sernum;
1215                 fn = rcu_dereference_protected(fn->parent,
1216                                 lockdep_is_held(&rt->fib6_table->tb6_lock));
1217         }
1218 }
1219
1220 void fib6_update_sernum_upto_root(struct net *net, struct fib6_info *rt)
1221 {
1222         __fib6_update_sernum_upto_root(rt, fib6_new_sernum(net));
1223 }
1224
1225 /*
1226  *      Add routing information to the routing tree.
1227  *      <destination addr>/<source addr>
1228  *      with source addr info in sub-trees
1229  *      Need to own table->tb6_lock
1230  */
1231
1232 int fib6_add(struct fib6_node *root, struct fib6_info *rt,
1233              struct nl_info *info, struct netlink_ext_ack *extack)
1234 {
1235         struct fib6_table *table = rt->fib6_table;
1236         struct fib6_node *fn, *pn = NULL;
1237         int err = -ENOMEM;
1238         int allow_create = 1;
1239         int replace_required = 0;
1240         int sernum = fib6_new_sernum(info->nl_net);
1241
1242         if (info->nlh) {
1243                 if (!(info->nlh->nlmsg_flags & NLM_F_CREATE))
1244                         allow_create = 0;
1245                 if (info->nlh->nlmsg_flags & NLM_F_REPLACE)
1246                         replace_required = 1;
1247         }
1248         if (!allow_create && !replace_required)
1249                 pr_warn("RTM_NEWROUTE with no NLM_F_CREATE or NLM_F_REPLACE\n");
1250
1251         fn = fib6_add_1(info->nl_net, table, root,
1252                         &rt->fib6_dst.addr, rt->fib6_dst.plen,
1253                         offsetof(struct fib6_info, fib6_dst), allow_create,
1254                         replace_required, extack);
1255         if (IS_ERR(fn)) {
1256                 err = PTR_ERR(fn);
1257                 fn = NULL;
1258                 goto out;
1259         }
1260
1261         pn = fn;
1262
1263 #ifdef CONFIG_IPV6_SUBTREES
1264         if (rt->fib6_src.plen) {
1265                 struct fib6_node *sn;
1266
1267                 if (!rcu_access_pointer(fn->subtree)) {
1268                         struct fib6_node *sfn;
1269
1270                         /*
1271                          * Create subtree.
1272                          *
1273                          *              fn[main tree]
1274                          *              |
1275                          *              sfn[subtree root]
1276                          *                 \
1277                          *                  sn[new leaf node]
1278                          */
1279
1280                         /* Create subtree root node */
1281                         sfn = node_alloc(info->nl_net);
1282                         if (!sfn)
1283                                 goto failure;
1284
1285                         fib6_info_hold(info->nl_net->ipv6.fib6_null_entry);
1286                         rcu_assign_pointer(sfn->leaf,
1287                                            info->nl_net->ipv6.fib6_null_entry);
1288                         sfn->fn_flags = RTN_ROOT;
1289
1290                         /* Now add the first leaf node to new subtree */
1291
1292                         sn = fib6_add_1(info->nl_net, table, sfn,
1293                                         &rt->fib6_src.addr, rt->fib6_src.plen,
1294                                         offsetof(struct fib6_info, fib6_src),
1295                                         allow_create, replace_required, extack);
1296
1297                         if (IS_ERR(sn)) {
1298                                 /* If it is failed, discard just allocated
1299                                    root, and then (in failure) stale node
1300                                    in main tree.
1301                                  */
1302                                 node_free_immediate(info->nl_net, sfn);
1303                                 err = PTR_ERR(sn);
1304                                 goto failure;
1305                         }
1306
1307                         /* Now link new subtree to main tree */
1308                         rcu_assign_pointer(sfn->parent, fn);
1309                         rcu_assign_pointer(fn->subtree, sfn);
1310                 } else {
1311                         sn = fib6_add_1(info->nl_net, table, FIB6_SUBTREE(fn),
1312                                         &rt->fib6_src.addr, rt->fib6_src.plen,
1313                                         offsetof(struct fib6_info, fib6_src),
1314                                         allow_create, replace_required, extack);
1315
1316                         if (IS_ERR(sn)) {
1317                                 err = PTR_ERR(sn);
1318                                 goto failure;
1319                         }
1320                 }
1321
1322                 if (!rcu_access_pointer(fn->leaf)) {
1323                         if (fn->fn_flags & RTN_TL_ROOT) {
1324                                 /* put back null_entry for root node */
1325                                 rcu_assign_pointer(fn->leaf,
1326                                             info->nl_net->ipv6.fib6_null_entry);
1327                         } else {
1328                                 fib6_info_hold(rt);
1329                                 rcu_assign_pointer(fn->leaf, rt);
1330                         }
1331                 }
1332                 fn = sn;
1333         }
1334 #endif
1335
1336         err = fib6_add_rt2node(fn, rt, info, extack);
1337         if (!err) {
1338                 __fib6_update_sernum_upto_root(rt, sernum);
1339                 fib6_start_gc(info->nl_net, rt);
1340         }
1341
1342 out:
1343         if (err) {
1344 #ifdef CONFIG_IPV6_SUBTREES
1345                 /*
1346                  * If fib6_add_1 has cleared the old leaf pointer in the
1347                  * super-tree leaf node we have to find a new one for it.
1348                  */
1349                 if (pn != fn) {
1350                         struct fib6_info *pn_leaf =
1351                                 rcu_dereference_protected(pn->leaf,
1352                                     lockdep_is_held(&table->tb6_lock));
1353                         if (pn_leaf == rt) {
1354                                 pn_leaf = NULL;
1355                                 RCU_INIT_POINTER(pn->leaf, NULL);
1356                                 fib6_info_release(rt);
1357                         }
1358                         if (!pn_leaf && !(pn->fn_flags & RTN_RTINFO)) {
1359                                 pn_leaf = fib6_find_prefix(info->nl_net, table,
1360                                                            pn);
1361 #if RT6_DEBUG >= 2
1362                                 if (!pn_leaf) {
1363                                         WARN_ON(!pn_leaf);
1364                                         pn_leaf =
1365                                             info->nl_net->ipv6.fib6_null_entry;
1366                                 }
1367 #endif
1368                                 fib6_info_hold(pn_leaf);
1369                                 rcu_assign_pointer(pn->leaf, pn_leaf);
1370                         }
1371                 }
1372 #endif
1373                 goto failure;
1374         }
1375         return err;
1376
1377 failure:
1378         /* fn->leaf could be NULL and fib6_repair_tree() needs to be called if:
1379          * 1. fn is an intermediate node and we failed to add the new
1380          * route to it in both subtree creation failure and fib6_add_rt2node()
1381          * failure case.
1382          * 2. fn is the root node in the table and we fail to add the first
1383          * default route to it.
1384          */
1385         if (fn &&
1386             (!(fn->fn_flags & (RTN_RTINFO|RTN_ROOT)) ||
1387              (fn->fn_flags & RTN_TL_ROOT &&
1388               !rcu_access_pointer(fn->leaf))))
1389                 fib6_repair_tree(info->nl_net, table, fn);
1390         return err;
1391 }
1392
1393 /*
1394  *      Routing tree lookup
1395  *
1396  */
1397
1398 struct lookup_args {
1399         int                     offset;         /* key offset on fib6_info */
1400         const struct in6_addr   *addr;          /* search key                   */
1401 };
1402
1403 static struct fib6_node *fib6_node_lookup_1(struct fib6_node *root,
1404                                             struct lookup_args *args)
1405 {
1406         struct fib6_node *fn;
1407         __be32 dir;
1408
1409         if (unlikely(args->offset == 0))
1410                 return NULL;
1411
1412         /*
1413          *      Descend on a tree
1414          */
1415
1416         fn = root;
1417
1418         for (;;) {
1419                 struct fib6_node *next;
1420
1421                 dir = addr_bit_set(args->addr, fn->fn_bit);
1422
1423                 next = dir ? rcu_dereference(fn->right) :
1424                              rcu_dereference(fn->left);
1425
1426                 if (next) {
1427                         fn = next;
1428                         continue;
1429                 }
1430                 break;
1431         }
1432
1433         while (fn) {
1434                 struct fib6_node *subtree = FIB6_SUBTREE(fn);
1435
1436                 if (subtree || fn->fn_flags & RTN_RTINFO) {
1437                         struct fib6_info *leaf = rcu_dereference(fn->leaf);
1438                         struct rt6key *key;
1439
1440                         if (!leaf)
1441                                 goto backtrack;
1442
1443                         key = (struct rt6key *) ((u8 *)leaf + args->offset);
1444
1445                         if (ipv6_prefix_equal(&key->addr, args->addr, key->plen)) {
1446 #ifdef CONFIG_IPV6_SUBTREES
1447                                 if (subtree) {
1448                                         struct fib6_node *sfn;
1449                                         sfn = fib6_node_lookup_1(subtree,
1450                                                                  args + 1);
1451                                         if (!sfn)
1452                                                 goto backtrack;
1453                                         fn = sfn;
1454                                 }
1455 #endif
1456                                 if (fn->fn_flags & RTN_RTINFO)
1457                                         return fn;
1458                         }
1459                 }
1460 backtrack:
1461                 if (fn->fn_flags & RTN_ROOT)
1462                         break;
1463
1464                 fn = rcu_dereference(fn->parent);
1465         }
1466
1467         return NULL;
1468 }
1469
1470 /* called with rcu_read_lock() held
1471  */
1472 struct fib6_node *fib6_node_lookup(struct fib6_node *root,
1473                                    const struct in6_addr *daddr,
1474                                    const struct in6_addr *saddr)
1475 {
1476         struct fib6_node *fn;
1477         struct lookup_args args[] = {
1478                 {
1479                         .offset = offsetof(struct fib6_info, fib6_dst),
1480                         .addr = daddr,
1481                 },
1482 #ifdef CONFIG_IPV6_SUBTREES
1483                 {
1484                         .offset = offsetof(struct fib6_info, fib6_src),
1485                         .addr = saddr,
1486                 },
1487 #endif
1488                 {
1489                         .offset = 0,    /* sentinel */
1490                 }
1491         };
1492
1493         fn = fib6_node_lookup_1(root, daddr ? args : args + 1);
1494         if (!fn || fn->fn_flags & RTN_TL_ROOT)
1495                 fn = root;
1496
1497         return fn;
1498 }
1499
1500 /*
1501  *      Get node with specified destination prefix (and source prefix,
1502  *      if subtrees are used)
1503  *      exact_match == true means we try to find fn with exact match of
1504  *      the passed in prefix addr
1505  *      exact_match == false means we try to find fn with longest prefix
1506  *      match of the passed in prefix addr. This is useful for finding fn
1507  *      for cached route as it will be stored in the exception table under
1508  *      the node with longest prefix length.
1509  */
1510
1511
1512 static struct fib6_node *fib6_locate_1(struct fib6_node *root,
1513                                        const struct in6_addr *addr,
1514                                        int plen, int offset,
1515                                        bool exact_match)
1516 {
1517         struct fib6_node *fn, *prev = NULL;
1518
1519         for (fn = root; fn ; ) {
1520                 struct fib6_info *leaf = rcu_dereference(fn->leaf);
1521                 struct rt6key *key;
1522
1523                 /* This node is being deleted */
1524                 if (!leaf) {
1525                         if (plen <= fn->fn_bit)
1526                                 goto out;
1527                         else
1528                                 goto next;
1529                 }
1530
1531                 key = (struct rt6key *)((u8 *)leaf + offset);
1532
1533                 /*
1534                  *      Prefix match
1535                  */
1536                 if (plen < fn->fn_bit ||
1537                     !ipv6_prefix_equal(&key->addr, addr, fn->fn_bit))
1538                         goto out;
1539
1540                 if (plen == fn->fn_bit)
1541                         return fn;
1542
1543                 prev = fn;
1544
1545 next:
1546                 /*
1547                  *      We have more bits to go
1548                  */
1549                 if (addr_bit_set(addr, fn->fn_bit))
1550                         fn = rcu_dereference(fn->right);
1551                 else
1552                         fn = rcu_dereference(fn->left);
1553         }
1554 out:
1555         if (exact_match)
1556                 return NULL;
1557         else
1558                 return prev;
1559 }
1560
1561 struct fib6_node *fib6_locate(struct fib6_node *root,
1562                               const struct in6_addr *daddr, int dst_len,
1563                               const struct in6_addr *saddr, int src_len,
1564                               bool exact_match)
1565 {
1566         struct fib6_node *fn;
1567
1568         fn = fib6_locate_1(root, daddr, dst_len,
1569                            offsetof(struct fib6_info, fib6_dst),
1570                            exact_match);
1571
1572 #ifdef CONFIG_IPV6_SUBTREES
1573         if (src_len) {
1574                 WARN_ON(saddr == NULL);
1575                 if (fn) {
1576                         struct fib6_node *subtree = FIB6_SUBTREE(fn);
1577
1578                         if (subtree) {
1579                                 fn = fib6_locate_1(subtree, saddr, src_len,
1580                                            offsetof(struct fib6_info, fib6_src),
1581                                            exact_match);
1582                         }
1583                 }
1584         }
1585 #endif
1586
1587         if (fn && fn->fn_flags & RTN_RTINFO)
1588                 return fn;
1589
1590         return NULL;
1591 }
1592
1593
1594 /*
1595  *      Deletion
1596  *
1597  */
1598
1599 static struct fib6_info *fib6_find_prefix(struct net *net,
1600                                          struct fib6_table *table,
1601                                          struct fib6_node *fn)
1602 {
1603         struct fib6_node *child_left, *child_right;
1604
1605         if (fn->fn_flags & RTN_ROOT)
1606                 return net->ipv6.fib6_null_entry;
1607
1608         while (fn) {
1609                 child_left = rcu_dereference_protected(fn->left,
1610                                     lockdep_is_held(&table->tb6_lock));
1611                 child_right = rcu_dereference_protected(fn->right,
1612                                     lockdep_is_held(&table->tb6_lock));
1613                 if (child_left)
1614                         return rcu_dereference_protected(child_left->leaf,
1615                                         lockdep_is_held(&table->tb6_lock));
1616                 if (child_right)
1617                         return rcu_dereference_protected(child_right->leaf,
1618                                         lockdep_is_held(&table->tb6_lock));
1619
1620                 fn = FIB6_SUBTREE(fn);
1621         }
1622         return NULL;
1623 }
1624
1625 /*
1626  *      Called to trim the tree of intermediate nodes when possible. "fn"
1627  *      is the node we want to try and remove.
1628  *      Need to own table->tb6_lock
1629  */
1630
1631 static struct fib6_node *fib6_repair_tree(struct net *net,
1632                                           struct fib6_table *table,
1633                                           struct fib6_node *fn)
1634 {
1635         int children;
1636         int nstate;
1637         struct fib6_node *child;
1638         struct fib6_walker *w;
1639         int iter = 0;
1640
1641         /* Set fn->leaf to null_entry for root node. */
1642         if (fn->fn_flags & RTN_TL_ROOT) {
1643                 rcu_assign_pointer(fn->leaf, net->ipv6.fib6_null_entry);
1644                 return fn;
1645         }
1646
1647         for (;;) {
1648                 struct fib6_node *fn_r = rcu_dereference_protected(fn->right,
1649                                             lockdep_is_held(&table->tb6_lock));
1650                 struct fib6_node *fn_l = rcu_dereference_protected(fn->left,
1651                                             lockdep_is_held(&table->tb6_lock));
1652                 struct fib6_node *pn = rcu_dereference_protected(fn->parent,
1653                                             lockdep_is_held(&table->tb6_lock));
1654                 struct fib6_node *pn_r = rcu_dereference_protected(pn->right,
1655                                             lockdep_is_held(&table->tb6_lock));
1656                 struct fib6_node *pn_l = rcu_dereference_protected(pn->left,
1657                                             lockdep_is_held(&table->tb6_lock));
1658                 struct fib6_info *fn_leaf = rcu_dereference_protected(fn->leaf,
1659                                             lockdep_is_held(&table->tb6_lock));
1660                 struct fib6_info *pn_leaf = rcu_dereference_protected(pn->leaf,
1661                                             lockdep_is_held(&table->tb6_lock));
1662                 struct fib6_info *new_fn_leaf;
1663
1664                 RT6_TRACE("fixing tree: plen=%d iter=%d\n", fn->fn_bit, iter);
1665                 iter++;
1666
1667                 WARN_ON(fn->fn_flags & RTN_RTINFO);
1668                 WARN_ON(fn->fn_flags & RTN_TL_ROOT);
1669                 WARN_ON(fn_leaf);
1670
1671                 children = 0;
1672                 child = NULL;
1673                 if (fn_r)
1674                         child = fn_r, children |= 1;
1675                 if (fn_l)
1676                         child = fn_l, children |= 2;
1677
1678                 if (children == 3 || FIB6_SUBTREE(fn)
1679 #ifdef CONFIG_IPV6_SUBTREES
1680                     /* Subtree root (i.e. fn) may have one child */
1681                     || (children && fn->fn_flags & RTN_ROOT)
1682 #endif
1683                     ) {
1684                         new_fn_leaf = fib6_find_prefix(net, table, fn);
1685 #if RT6_DEBUG >= 2
1686                         if (!new_fn_leaf) {
1687                                 WARN_ON(!new_fn_leaf);
1688                                 new_fn_leaf = net->ipv6.fib6_null_entry;
1689                         }
1690 #endif
1691                         fib6_info_hold(new_fn_leaf);
1692                         rcu_assign_pointer(fn->leaf, new_fn_leaf);
1693                         return pn;
1694                 }
1695
1696 #ifdef CONFIG_IPV6_SUBTREES
1697                 if (FIB6_SUBTREE(pn) == fn) {
1698                         WARN_ON(!(fn->fn_flags & RTN_ROOT));
1699                         RCU_INIT_POINTER(pn->subtree, NULL);
1700                         nstate = FWS_L;
1701                 } else {
1702                         WARN_ON(fn->fn_flags & RTN_ROOT);
1703 #endif
1704                         if (pn_r == fn)
1705                                 rcu_assign_pointer(pn->right, child);
1706                         else if (pn_l == fn)
1707                                 rcu_assign_pointer(pn->left, child);
1708 #if RT6_DEBUG >= 2
1709                         else
1710                                 WARN_ON(1);
1711 #endif
1712                         if (child)
1713                                 rcu_assign_pointer(child->parent, pn);
1714                         nstate = FWS_R;
1715 #ifdef CONFIG_IPV6_SUBTREES
1716                 }
1717 #endif
1718
1719                 read_lock(&net->ipv6.fib6_walker_lock);
1720                 FOR_WALKERS(net, w) {
1721                         if (!child) {
1722                                 if (w->node == fn) {
1723                                         RT6_TRACE("W %p adjusted by delnode 1, s=%d/%d\n", w, w->state, nstate);
1724                                         w->node = pn;
1725                                         w->state = nstate;
1726                                 }
1727                         } else {
1728                                 if (w->node == fn) {
1729                                         w->node = child;
1730                                         if (children&2) {
1731                                                 RT6_TRACE("W %p adjusted by delnode 2, s=%d\n", w, w->state);
1732                                                 w->state = w->state >= FWS_R ? FWS_U : FWS_INIT;
1733                                         } else {
1734                                                 RT6_TRACE("W %p adjusted by delnode 2, s=%d\n", w, w->state);
1735                                                 w->state = w->state >= FWS_C ? FWS_U : FWS_INIT;
1736                                         }
1737                                 }
1738                         }
1739                 }
1740                 read_unlock(&net->ipv6.fib6_walker_lock);
1741
1742                 node_free(net, fn);
1743                 if (pn->fn_flags & RTN_RTINFO || FIB6_SUBTREE(pn))
1744                         return pn;
1745
1746                 RCU_INIT_POINTER(pn->leaf, NULL);
1747                 fib6_info_release(pn_leaf);
1748                 fn = pn;
1749         }
1750 }
1751
1752 static void fib6_del_route(struct fib6_table *table, struct fib6_node *fn,
1753                            struct fib6_info __rcu **rtp, struct nl_info *info)
1754 {
1755         struct fib6_walker *w;
1756         struct fib6_info *rt = rcu_dereference_protected(*rtp,
1757                                     lockdep_is_held(&table->tb6_lock));
1758         struct net *net = info->nl_net;
1759
1760         RT6_TRACE("fib6_del_route\n");
1761
1762         /* Unlink it */
1763         *rtp = rt->fib6_next;
1764         rt->fib6_node = NULL;
1765         net->ipv6.rt6_stats->fib_rt_entries--;
1766         net->ipv6.rt6_stats->fib_discarded_routes++;
1767
1768         /* Flush all cached dst in exception table */
1769         rt6_flush_exceptions(rt);
1770
1771         /* Reset round-robin state, if necessary */
1772         if (rcu_access_pointer(fn->rr_ptr) == rt)
1773                 fn->rr_ptr = NULL;
1774
1775         /* Remove this entry from other siblings */
1776         if (rt->fib6_nsiblings) {
1777                 struct fib6_info *sibling, *next_sibling;
1778
1779                 list_for_each_entry_safe(sibling, next_sibling,
1780                                          &rt->fib6_siblings, fib6_siblings)
1781                         sibling->fib6_nsiblings--;
1782                 rt->fib6_nsiblings = 0;
1783                 list_del_init(&rt->fib6_siblings);
1784                 rt6_multipath_rebalance(next_sibling);
1785         }
1786
1787         /* Adjust walkers */
1788         read_lock(&net->ipv6.fib6_walker_lock);
1789         FOR_WALKERS(net, w) {
1790                 if (w->state == FWS_C && w->leaf == rt) {
1791                         RT6_TRACE("walker %p adjusted by delroute\n", w);
1792                         w->leaf = rcu_dereference_protected(rt->fib6_next,
1793                                             lockdep_is_held(&table->tb6_lock));
1794                         if (!w->leaf)
1795                                 w->state = FWS_U;
1796                 }
1797         }
1798         read_unlock(&net->ipv6.fib6_walker_lock);
1799
1800         /* If it was last route, call fib6_repair_tree() to:
1801          * 1. For root node, put back null_entry as how the table was created.
1802          * 2. For other nodes, expunge its radix tree node.
1803          */
1804         if (!rcu_access_pointer(fn->leaf)) {
1805                 if (!(fn->fn_flags & RTN_TL_ROOT)) {
1806                         fn->fn_flags &= ~RTN_RTINFO;
1807                         net->ipv6.rt6_stats->fib_route_nodes--;
1808                 }
1809                 fn = fib6_repair_tree(net, table, fn);
1810         }
1811
1812         fib6_purge_rt(rt, fn, net);
1813
1814         call_fib6_entry_notifiers(net, FIB_EVENT_ENTRY_DEL, rt, NULL);
1815         if (!info->skip_notify)
1816                 inet6_rt_notify(RTM_DELROUTE, rt, info, 0);
1817         fib6_info_release(rt);
1818 }
1819
1820 /* Need to own table->tb6_lock */
1821 int fib6_del(struct fib6_info *rt, struct nl_info *info)
1822 {
1823         struct fib6_node *fn = rcu_dereference_protected(rt->fib6_node,
1824                                     lockdep_is_held(&rt->fib6_table->tb6_lock));
1825         struct fib6_table *table = rt->fib6_table;
1826         struct net *net = info->nl_net;
1827         struct fib6_info __rcu **rtp;
1828         struct fib6_info __rcu **rtp_next;
1829
1830         if (!fn || rt == net->ipv6.fib6_null_entry)
1831                 return -ENOENT;
1832
1833         WARN_ON(!(fn->fn_flags & RTN_RTINFO));
1834
1835         /*
1836          *      Walk the leaf entries looking for ourself
1837          */
1838
1839         for (rtp = &fn->leaf; *rtp; rtp = rtp_next) {
1840                 struct fib6_info *cur = rcu_dereference_protected(*rtp,
1841                                         lockdep_is_held(&table->tb6_lock));
1842                 if (rt == cur) {
1843                         fib6_del_route(table, fn, rtp, info);
1844                         return 0;
1845                 }
1846                 rtp_next = &cur->fib6_next;
1847         }
1848         return -ENOENT;
1849 }
1850
1851 /*
1852  *      Tree traversal function.
1853  *
1854  *      Certainly, it is not interrupt safe.
1855  *      However, it is internally reenterable wrt itself and fib6_add/fib6_del.
1856  *      It means, that we can modify tree during walking
1857  *      and use this function for garbage collection, clone pruning,
1858  *      cleaning tree when a device goes down etc. etc.
1859  *
1860  *      It guarantees that every node will be traversed,
1861  *      and that it will be traversed only once.
1862  *
1863  *      Callback function w->func may return:
1864  *      0 -> continue walking.
1865  *      positive value -> walking is suspended (used by tree dumps,
1866  *      and probably by gc, if it will be split to several slices)
1867  *      negative value -> terminate walking.
1868  *
1869  *      The function itself returns:
1870  *      0   -> walk is complete.
1871  *      >0  -> walk is incomplete (i.e. suspended)
1872  *      <0  -> walk is terminated by an error.
1873  *
1874  *      This function is called with tb6_lock held.
1875  */
1876
1877 static int fib6_walk_continue(struct fib6_walker *w)
1878 {
1879         struct fib6_node *fn, *pn, *left, *right;
1880
1881         /* w->root should always be table->tb6_root */
1882         WARN_ON_ONCE(!(w->root->fn_flags & RTN_TL_ROOT));
1883
1884         for (;;) {
1885                 fn = w->node;
1886                 if (!fn)
1887                         return 0;
1888
1889                 switch (w->state) {
1890 #ifdef CONFIG_IPV6_SUBTREES
1891                 case FWS_S:
1892                         if (FIB6_SUBTREE(fn)) {
1893                                 w->node = FIB6_SUBTREE(fn);
1894                                 continue;
1895                         }
1896                         w->state = FWS_L;
1897 #endif
1898                         /* fall through */
1899                 case FWS_L:
1900                         left = rcu_dereference_protected(fn->left, 1);
1901                         if (left) {
1902                                 w->node = left;
1903                                 w->state = FWS_INIT;
1904                                 continue;
1905                         }
1906                         w->state = FWS_R;
1907                         /* fall through */
1908                 case FWS_R:
1909                         right = rcu_dereference_protected(fn->right, 1);
1910                         if (right) {
1911                                 w->node = right;
1912                                 w->state = FWS_INIT;
1913                                 continue;
1914                         }
1915                         w->state = FWS_C;
1916                         w->leaf = rcu_dereference_protected(fn->leaf, 1);
1917                         /* fall through */
1918                 case FWS_C:
1919                         if (w->leaf && fn->fn_flags & RTN_RTINFO) {
1920                                 int err;
1921
1922                                 if (w->skip) {
1923                                         w->skip--;
1924                                         goto skip;
1925                                 }
1926
1927                                 err = w->func(w);
1928                                 if (err)
1929                                         return err;
1930
1931                                 w->count++;
1932                                 continue;
1933                         }
1934 skip:
1935                         w->state = FWS_U;
1936                         /* fall through */
1937                 case FWS_U:
1938                         if (fn == w->root)
1939                                 return 0;
1940                         pn = rcu_dereference_protected(fn->parent, 1);
1941                         left = rcu_dereference_protected(pn->left, 1);
1942                         right = rcu_dereference_protected(pn->right, 1);
1943                         w->node = pn;
1944 #ifdef CONFIG_IPV6_SUBTREES
1945                         if (FIB6_SUBTREE(pn) == fn) {
1946                                 WARN_ON(!(fn->fn_flags & RTN_ROOT));
1947                                 w->state = FWS_L;
1948                                 continue;
1949                         }
1950 #endif
1951                         if (left == fn) {
1952                                 w->state = FWS_R;
1953                                 continue;
1954                         }
1955                         if (right == fn) {
1956                                 w->state = FWS_C;
1957                                 w->leaf = rcu_dereference_protected(w->node->leaf, 1);
1958                                 continue;
1959                         }
1960 #if RT6_DEBUG >= 2
1961                         WARN_ON(1);
1962 #endif
1963                 }
1964         }
1965 }
1966
1967 static int fib6_walk(struct net *net, struct fib6_walker *w)
1968 {
1969         int res;
1970
1971         w->state = FWS_INIT;
1972         w->node = w->root;
1973
1974         fib6_walker_link(net, w);
1975         res = fib6_walk_continue(w);
1976         if (res <= 0)
1977                 fib6_walker_unlink(net, w);
1978         return res;
1979 }
1980
1981 static int fib6_clean_node(struct fib6_walker *w)
1982 {
1983         int res;
1984         struct fib6_info *rt;
1985         struct fib6_cleaner *c = container_of(w, struct fib6_cleaner, w);
1986         struct nl_info info = {
1987                 .nl_net = c->net,
1988                 .skip_notify = c->skip_notify,
1989         };
1990
1991         if (c->sernum != FIB6_NO_SERNUM_CHANGE &&
1992             w->node->fn_sernum != c->sernum)
1993                 w->node->fn_sernum = c->sernum;
1994
1995         if (!c->func) {
1996                 WARN_ON_ONCE(c->sernum == FIB6_NO_SERNUM_CHANGE);
1997                 w->leaf = NULL;
1998                 return 0;
1999         }
2000
2001         for_each_fib6_walker_rt(w) {
2002                 res = c->func(rt, c->arg);
2003                 if (res == -1) {
2004                         w->leaf = rt;
2005                         res = fib6_del(rt, &info);
2006                         if (res) {
2007 #if RT6_DEBUG >= 2
2008                                 pr_debug("%s: del failed: rt=%p@%p err=%d\n",
2009                                          __func__, rt,
2010                                          rcu_access_pointer(rt->fib6_node),
2011                                          res);
2012 #endif
2013                                 continue;
2014                         }
2015                         return 0;
2016                 } else if (res == -2) {
2017                         if (WARN_ON(!rt->fib6_nsiblings))
2018                                 continue;
2019                         rt = list_last_entry(&rt->fib6_siblings,
2020                                              struct fib6_info, fib6_siblings);
2021                         continue;
2022                 }
2023                 WARN_ON(res != 0);
2024         }
2025         w->leaf = rt;
2026         return 0;
2027 }
2028
2029 /*
2030  *      Convenient frontend to tree walker.
2031  *
2032  *      func is called on each route.
2033  *              It may return -2 -> skip multipath route.
2034  *                            -1 -> delete this route.
2035  *                            0  -> continue walking
2036  */
2037
2038 static void fib6_clean_tree(struct net *net, struct fib6_node *root,
2039                             int (*func)(struct fib6_info *, void *arg),
2040                             int sernum, void *arg, bool skip_notify)
2041 {
2042         struct fib6_cleaner c;
2043
2044         c.w.root = root;
2045         c.w.func = fib6_clean_node;
2046         c.w.count = 0;
2047         c.w.skip = 0;
2048         c.func = func;
2049         c.sernum = sernum;
2050         c.arg = arg;
2051         c.net = net;
2052         c.skip_notify = skip_notify;
2053
2054         fib6_walk(net, &c.w);
2055 }
2056
2057 static void __fib6_clean_all(struct net *net,
2058                              int (*func)(struct fib6_info *, void *),
2059                              int sernum, void *arg, bool skip_notify)
2060 {
2061         struct fib6_table *table;
2062         struct hlist_head *head;
2063         unsigned int h;
2064
2065         rcu_read_lock();
2066         for (h = 0; h < FIB6_TABLE_HASHSZ; h++) {
2067                 head = &net->ipv6.fib_table_hash[h];
2068                 hlist_for_each_entry_rcu(table, head, tb6_hlist) {
2069                         spin_lock_bh(&table->tb6_lock);
2070                         fib6_clean_tree(net, &table->tb6_root,
2071                                         func, sernum, arg, skip_notify);
2072                         spin_unlock_bh(&table->tb6_lock);
2073                 }
2074         }
2075         rcu_read_unlock();
2076 }
2077
2078 void fib6_clean_all(struct net *net, int (*func)(struct fib6_info *, void *),
2079                     void *arg)
2080 {
2081         __fib6_clean_all(net, func, FIB6_NO_SERNUM_CHANGE, arg, false);
2082 }
2083
2084 void fib6_clean_all_skip_notify(struct net *net,
2085                                 int (*func)(struct fib6_info *, void *),
2086                                 void *arg)
2087 {
2088         __fib6_clean_all(net, func, FIB6_NO_SERNUM_CHANGE, arg, true);
2089 }
2090
2091 static void fib6_flush_trees(struct net *net)
2092 {
2093         int new_sernum = fib6_new_sernum(net);
2094
2095         __fib6_clean_all(net, NULL, new_sernum, NULL, false);
2096 }
2097
2098 /*
2099  *      Garbage collection
2100  */
2101
2102 static int fib6_age(struct fib6_info *rt, void *arg)
2103 {
2104         struct fib6_gc_args *gc_args = arg;
2105         unsigned long now = jiffies;
2106
2107         /*
2108          *      check addrconf expiration here.
2109          *      Routes are expired even if they are in use.
2110          */
2111
2112         if (rt->fib6_flags & RTF_EXPIRES && rt->expires) {
2113                 if (time_after(now, rt->expires)) {
2114                         RT6_TRACE("expiring %p\n", rt);
2115                         return -1;
2116                 }
2117                 gc_args->more++;
2118         }
2119
2120         /*      Also age clones in the exception table.
2121          *      Note, that clones are aged out
2122          *      only if they are not in use now.
2123          */
2124         rt6_age_exceptions(rt, gc_args, now);
2125
2126         return 0;
2127 }
2128
2129 void fib6_run_gc(unsigned long expires, struct net *net, bool force)
2130 {
2131         struct fib6_gc_args gc_args;
2132         unsigned long now;
2133
2134         if (force) {
2135                 spin_lock_bh(&net->ipv6.fib6_gc_lock);
2136         } else if (!spin_trylock_bh(&net->ipv6.fib6_gc_lock)) {
2137                 mod_timer(&net->ipv6.ip6_fib_timer, jiffies + HZ);
2138                 return;
2139         }
2140         gc_args.timeout = expires ? (int)expires :
2141                           net->ipv6.sysctl.ip6_rt_gc_interval;
2142         gc_args.more = 0;
2143
2144         fib6_clean_all(net, fib6_age, &gc_args);
2145         now = jiffies;
2146         net->ipv6.ip6_rt_last_gc = now;
2147
2148         if (gc_args.more)
2149                 mod_timer(&net->ipv6.ip6_fib_timer,
2150                           round_jiffies(now
2151                                         + net->ipv6.sysctl.ip6_rt_gc_interval));
2152         else
2153                 del_timer(&net->ipv6.ip6_fib_timer);
2154         spin_unlock_bh(&net->ipv6.fib6_gc_lock);
2155 }
2156
2157 static void fib6_gc_timer_cb(struct timer_list *t)
2158 {
2159         struct net *arg = from_timer(arg, t, ipv6.ip6_fib_timer);
2160
2161         fib6_run_gc(0, arg, true);
2162 }
2163
2164 static int __net_init fib6_net_init(struct net *net)
2165 {
2166         size_t size = sizeof(struct hlist_head) * FIB6_TABLE_HASHSZ;
2167         int err;
2168
2169         err = fib6_notifier_init(net);
2170         if (err)
2171                 return err;
2172
2173         spin_lock_init(&net->ipv6.fib6_gc_lock);
2174         rwlock_init(&net->ipv6.fib6_walker_lock);
2175         INIT_LIST_HEAD(&net->ipv6.fib6_walkers);
2176         timer_setup(&net->ipv6.ip6_fib_timer, fib6_gc_timer_cb, 0);
2177
2178         net->ipv6.rt6_stats = kzalloc(sizeof(*net->ipv6.rt6_stats), GFP_KERNEL);
2179         if (!net->ipv6.rt6_stats)
2180                 goto out_timer;
2181
2182         /* Avoid false sharing : Use at least a full cache line */
2183         size = max_t(size_t, size, L1_CACHE_BYTES);
2184
2185         net->ipv6.fib_table_hash = kzalloc(size, GFP_KERNEL);
2186         if (!net->ipv6.fib_table_hash)
2187                 goto out_rt6_stats;
2188
2189         net->ipv6.fib6_main_tbl = kzalloc(sizeof(*net->ipv6.fib6_main_tbl),
2190                                           GFP_KERNEL);
2191         if (!net->ipv6.fib6_main_tbl)
2192                 goto out_fib_table_hash;
2193
2194         net->ipv6.fib6_main_tbl->tb6_id = RT6_TABLE_MAIN;
2195         rcu_assign_pointer(net->ipv6.fib6_main_tbl->tb6_root.leaf,
2196                            net->ipv6.fib6_null_entry);
2197         net->ipv6.fib6_main_tbl->tb6_root.fn_flags =
2198                 RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
2199         inet_peer_base_init(&net->ipv6.fib6_main_tbl->tb6_peers);
2200
2201 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
2202         net->ipv6.fib6_local_tbl = kzalloc(sizeof(*net->ipv6.fib6_local_tbl),
2203                                            GFP_KERNEL);
2204         if (!net->ipv6.fib6_local_tbl)
2205                 goto out_fib6_main_tbl;
2206         net->ipv6.fib6_local_tbl->tb6_id = RT6_TABLE_LOCAL;
2207         rcu_assign_pointer(net->ipv6.fib6_local_tbl->tb6_root.leaf,
2208                            net->ipv6.fib6_null_entry);
2209         net->ipv6.fib6_local_tbl->tb6_root.fn_flags =
2210                 RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
2211         inet_peer_base_init(&net->ipv6.fib6_local_tbl->tb6_peers);
2212 #endif
2213         fib6_tables_init(net);
2214
2215         return 0;
2216
2217 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
2218 out_fib6_main_tbl:
2219         kfree(net->ipv6.fib6_main_tbl);
2220 #endif
2221 out_fib_table_hash:
2222         kfree(net->ipv6.fib_table_hash);
2223 out_rt6_stats:
2224         kfree(net->ipv6.rt6_stats);
2225 out_timer:
2226         fib6_notifier_exit(net);
2227         return -ENOMEM;
2228 }
2229
2230 static void fib6_net_exit(struct net *net)
2231 {
2232         unsigned int i;
2233
2234         del_timer_sync(&net->ipv6.ip6_fib_timer);
2235
2236         for (i = 0; i < FIB6_TABLE_HASHSZ; i++) {
2237                 struct hlist_head *head = &net->ipv6.fib_table_hash[i];
2238                 struct hlist_node *tmp;
2239                 struct fib6_table *tb;
2240
2241                 hlist_for_each_entry_safe(tb, tmp, head, tb6_hlist) {
2242                         hlist_del(&tb->tb6_hlist);
2243                         fib6_free_table(tb);
2244                 }
2245         }
2246
2247         kfree(net->ipv6.fib_table_hash);
2248         kfree(net->ipv6.rt6_stats);
2249         fib6_notifier_exit(net);
2250 }
2251
2252 static struct pernet_operations fib6_net_ops = {
2253         .init = fib6_net_init,
2254         .exit = fib6_net_exit,
2255 };
2256
2257 int __init fib6_init(void)
2258 {
2259         int ret = -ENOMEM;
2260
2261         fib6_node_kmem = kmem_cache_create("fib6_nodes",
2262                                            sizeof(struct fib6_node),
2263                                            0, SLAB_HWCACHE_ALIGN,
2264                                            NULL);
2265         if (!fib6_node_kmem)
2266                 goto out;
2267
2268         ret = register_pernet_subsys(&fib6_net_ops);
2269         if (ret)
2270                 goto out_kmem_cache_create;
2271
2272         ret = rtnl_register_module(THIS_MODULE, PF_INET6, RTM_GETROUTE, NULL,
2273                                    inet6_dump_fib, 0);
2274         if (ret)
2275                 goto out_unregister_subsys;
2276
2277         __fib6_flush_trees = fib6_flush_trees;
2278 out:
2279         return ret;
2280
2281 out_unregister_subsys:
2282         unregister_pernet_subsys(&fib6_net_ops);
2283 out_kmem_cache_create:
2284         kmem_cache_destroy(fib6_node_kmem);
2285         goto out;
2286 }
2287
2288 void fib6_gc_cleanup(void)
2289 {
2290         unregister_pernet_subsys(&fib6_net_ops);
2291         kmem_cache_destroy(fib6_node_kmem);
2292 }
2293
2294 #ifdef CONFIG_PROC_FS
2295 static int ipv6_route_seq_show(struct seq_file *seq, void *v)
2296 {
2297         struct fib6_info *rt = v;
2298         struct ipv6_route_iter *iter = seq->private;
2299         unsigned int flags = rt->fib6_flags;
2300         const struct net_device *dev;
2301
2302         seq_printf(seq, "%pi6 %02x ", &rt->fib6_dst.addr, rt->fib6_dst.plen);
2303
2304 #ifdef CONFIG_IPV6_SUBTREES
2305         seq_printf(seq, "%pi6 %02x ", &rt->fib6_src.addr, rt->fib6_src.plen);
2306 #else
2307         seq_puts(seq, "00000000000000000000000000000000 00 ");
2308 #endif
2309         if (rt->fib6_nh.fib_nh_gw_family) {
2310                 flags |= RTF_GATEWAY;
2311                 seq_printf(seq, "%pi6", &rt->fib6_nh.fib_nh_gw6);
2312         } else {
2313                 seq_puts(seq, "00000000000000000000000000000000");
2314         }
2315
2316         dev = rt->fib6_nh.fib_nh_dev;
2317         seq_printf(seq, " %08x %08x %08x %08x %8s\n",
2318                    rt->fib6_metric, refcount_read(&rt->fib6_ref), 0,
2319                    flags, dev ? dev->name : "");
2320         iter->w.leaf = NULL;
2321         return 0;
2322 }
2323
2324 static int ipv6_route_yield(struct fib6_walker *w)
2325 {
2326         struct ipv6_route_iter *iter = w->args;
2327
2328         if (!iter->skip)
2329                 return 1;
2330
2331         do {
2332                 iter->w.leaf = rcu_dereference_protected(
2333                                 iter->w.leaf->fib6_next,
2334                                 lockdep_is_held(&iter->tbl->tb6_lock));
2335                 iter->skip--;
2336                 if (!iter->skip && iter->w.leaf)
2337                         return 1;
2338         } while (iter->w.leaf);
2339
2340         return 0;
2341 }
2342
2343 static void ipv6_route_seq_setup_walk(struct ipv6_route_iter *iter,
2344                                       struct net *net)
2345 {
2346         memset(&iter->w, 0, sizeof(iter->w));
2347         iter->w.func = ipv6_route_yield;
2348         iter->w.root = &iter->tbl->tb6_root;
2349         iter->w.state = FWS_INIT;
2350         iter->w.node = iter->w.root;
2351         iter->w.args = iter;
2352         iter->sernum = iter->w.root->fn_sernum;
2353         INIT_LIST_HEAD(&iter->w.lh);
2354         fib6_walker_link(net, &iter->w);
2355 }
2356
2357 static struct fib6_table *ipv6_route_seq_next_table(struct fib6_table *tbl,
2358                                                     struct net *net)
2359 {
2360         unsigned int h;
2361         struct hlist_node *node;
2362
2363         if (tbl) {
2364                 h = (tbl->tb6_id & (FIB6_TABLE_HASHSZ - 1)) + 1;
2365                 node = rcu_dereference_bh(hlist_next_rcu(&tbl->tb6_hlist));
2366         } else {
2367                 h = 0;
2368                 node = NULL;
2369         }
2370
2371         while (!node && h < FIB6_TABLE_HASHSZ) {
2372                 node = rcu_dereference_bh(
2373                         hlist_first_rcu(&net->ipv6.fib_table_hash[h++]));
2374         }
2375         return hlist_entry_safe(node, struct fib6_table, tb6_hlist);
2376 }
2377
2378 static void ipv6_route_check_sernum(struct ipv6_route_iter *iter)
2379 {
2380         if (iter->sernum != iter->w.root->fn_sernum) {
2381                 iter->sernum = iter->w.root->fn_sernum;
2382                 iter->w.state = FWS_INIT;
2383                 iter->w.node = iter->w.root;
2384                 WARN_ON(iter->w.skip);
2385                 iter->w.skip = iter->w.count;
2386         }
2387 }
2388
2389 static void *ipv6_route_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2390 {
2391         int r;
2392         struct fib6_info *n;
2393         struct net *net = seq_file_net(seq);
2394         struct ipv6_route_iter *iter = seq->private;
2395
2396         if (!v)
2397                 goto iter_table;
2398
2399         n = rcu_dereference_bh(((struct fib6_info *)v)->fib6_next);
2400         if (n) {
2401                 ++*pos;
2402                 return n;
2403         }
2404
2405 iter_table:
2406         ipv6_route_check_sernum(iter);
2407         spin_lock_bh(&iter->tbl->tb6_lock);
2408         r = fib6_walk_continue(&iter->w);
2409         spin_unlock_bh(&iter->tbl->tb6_lock);
2410         if (r > 0) {
2411                 if (v)
2412                         ++*pos;
2413                 return iter->w.leaf;
2414         } else if (r < 0) {
2415                 fib6_walker_unlink(net, &iter->w);
2416                 return NULL;
2417         }
2418         fib6_walker_unlink(net, &iter->w);
2419
2420         iter->tbl = ipv6_route_seq_next_table(iter->tbl, net);
2421         if (!iter->tbl)
2422                 return NULL;
2423
2424         ipv6_route_seq_setup_walk(iter, net);
2425         goto iter_table;
2426 }
2427
2428 static void *ipv6_route_seq_start(struct seq_file *seq, loff_t *pos)
2429         __acquires(RCU_BH)
2430 {
2431         struct net *net = seq_file_net(seq);
2432         struct ipv6_route_iter *iter = seq->private;
2433
2434         rcu_read_lock_bh();
2435         iter->tbl = ipv6_route_seq_next_table(NULL, net);
2436         iter->skip = *pos;
2437
2438         if (iter->tbl) {
2439                 ipv6_route_seq_setup_walk(iter, net);
2440                 return ipv6_route_seq_next(seq, NULL, pos);
2441         } else {
2442                 return NULL;
2443         }
2444 }
2445
2446 static bool ipv6_route_iter_active(struct ipv6_route_iter *iter)
2447 {
2448         struct fib6_walker *w = &iter->w;
2449         return w->node && !(w->state == FWS_U && w->node == w->root);
2450 }
2451
2452 static void ipv6_route_seq_stop(struct seq_file *seq, void *v)
2453         __releases(RCU_BH)
2454 {
2455         struct net *net = seq_file_net(seq);
2456         struct ipv6_route_iter *iter = seq->private;
2457
2458         if (ipv6_route_iter_active(iter))
2459                 fib6_walker_unlink(net, &iter->w);
2460
2461         rcu_read_unlock_bh();
2462 }
2463
2464 const struct seq_operations ipv6_route_seq_ops = {
2465         .start  = ipv6_route_seq_start,
2466         .next   = ipv6_route_seq_next,
2467         .stop   = ipv6_route_seq_stop,
2468         .show   = ipv6_route_seq_show
2469 };
2470 #endif /* CONFIG_PROC_FS */