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/ipv6.h>
  33 #include <net/ndisc.h>
  34 #include <net/addrconf.h>
  35 #include <net/lwtunnel.h>
  36
  37 #include <net/ip6_fib.h>
  38 #include <net/ip6_route.h>
  39
  40 #define RT6_DEBUG 2
  41
  42 #if RT6_DEBUG >= 3
  43 #define RT6_TRACE(x...) pr_debug(x)
  44 #else
  45 #define RT6_TRACE(x...) do { ; } while (0)
  46 #endif
  47
  48 static struct kmem_cache *fib6_node_kmem __read_mostly;
  49
  50 struct fib6_cleaner {
  51         struct fib6_walker w;
  52         struct net *net;
  53         int (*func)(struct rt6_info *, void *arg);
  54         int sernum;
  55         void *arg;
  56 };
  57
  58 #ifdef CONFIG_IPV6_SUBTREES
  59 #define FWS_INIT FWS_S
  60 #else
  61 #define FWS_INIT FWS_L
  62 #endif
  63
  64 static void fib6_prune_clones(struct net *net, struct fib6_node *fn);
  65 static struct rt6_info *fib6_find_prefix(struct net *net, struct fib6_node *fn);
  66 static struct fib6_node *fib6_repair_tree(struct net *net, struct fib6_node *fn);
  67 static int fib6_walk(struct net *net, struct fib6_walker *w);
  68 static int fib6_walk_continue(struct fib6_walker *w);
  69
  70 /*
  71  *      A routing update causes an increase of the serial number on the
  72  *      affected subtree. This allows for cached routes to be asynchronously
  73  *      tested when modifications are made to the destination cache as a
  74  *      result of redirects, path MTU changes, etc.
  75  */
  76
  77 static void fib6_gc_timer_cb(unsigned long arg);
  78
  79 #define FOR_WALKERS(net, w) \
  80         list_for_each_entry(w, &(net)->ipv6.fib6_walkers, lh)
  81
  82 static void fib6_walker_link(struct net *net, struct fib6_walker *w)
  83 {
  84         write_lock_bh(&net->ipv6.fib6_walker_lock);
  85         list_add(&w->lh, &net->ipv6.fib6_walkers);
  86         write_unlock_bh(&net->ipv6.fib6_walker_lock);
  87 }
  88
  89 static void fib6_walker_unlink(struct net *net, struct fib6_walker *w)
  90 {
  91         write_lock_bh(&net->ipv6.fib6_walker_lock);
  92         list_del(&w->lh);
  93         write_unlock_bh(&net->ipv6.fib6_walker_lock);
  94 }
  95
  96 static int fib6_new_sernum(struct net *net)
  97 {
  98         int new, old;
  99
 100         do {
 101                 old = atomic_read(&net->ipv6.fib6_sernum);
 102                 new = old < INT_MAX ? old + 1 : 1;
 103         } while (atomic_cmpxchg(&net->ipv6.fib6_sernum,
 104                                 old, new) != old);
 105         return new;
 106 }
 107
 108 enum {
 109         FIB6_NO_SERNUM_CHANGE = 0,
 110 };
 111
 112 /*
 113  *      Auxiliary address test functions for the radix tree.
 114  *
 115  *      These assume a 32bit processor (although it will work on
 116  *      64bit processors)
 117  */
 118
 119 /*
 120  *      test bit
 121  */
 122 #if defined(__LITTLE_ENDIAN)
 123 # define BITOP_BE32_SWIZZLE     (0x1F & ~7)
 124 #else
 125 # define BITOP_BE32_SWIZZLE     0
 126 #endif
 127
 128 static __be32 addr_bit_set(const void *token, int fn_bit)
 129 {
 130         const __be32 *addr = token;
 131         /*
 132          * Here,
 133          *      1 << ((~fn_bit ^ BITOP_BE32_SWIZZLE) & 0x1f)
 134          * is optimized version of
 135          *      htonl(1 << ((~fn_bit)&0x1F))
 136          * See include/asm-generic/bitops/le.h.
 137          */
 138         return (__force __be32)(1 << ((~fn_bit ^ BITOP_BE32_SWIZZLE) & 0x1f)) &
 139                addr[fn_bit >> 5];
 140 }
 141
 142 static struct fib6_node *node_alloc(void)
 143 {
 144         struct fib6_node *fn;
 145
 146         fn = kmem_cache_zalloc(fib6_node_kmem, GFP_ATOMIC);
 147
 148         return fn;
 149 }
 150
 151 static void node_free(struct fib6_node *fn)
 152 {
 153         kmem_cache_free(fib6_node_kmem, fn);
 154 }
 155
 156 static void rt6_free_pcpu(struct rt6_info *non_pcpu_rt)
 157 {
 158         int cpu;
 159
 160         if (!non_pcpu_rt->rt6i_pcpu)
 161                 return;
 162
 163         for_each_possible_cpu(cpu) {
 164                 struct rt6_info **ppcpu_rt;
 165                 struct rt6_info *pcpu_rt;
 166
 167                 ppcpu_rt = per_cpu_ptr(non_pcpu_rt->rt6i_pcpu, cpu);
 168                 pcpu_rt = *ppcpu_rt;
 169                 if (pcpu_rt) {
 170                         dst_dev_put(&pcpu_rt->dst);
 171                         dst_release(&pcpu_rt->dst);
 172                         *ppcpu_rt = NULL;
 173                 }
 174         }
 175
 176         free_percpu(non_pcpu_rt->rt6i_pcpu);
 177         non_pcpu_rt->rt6i_pcpu = NULL;
 178 }
 179
 180 static void rt6_release(struct rt6_info *rt)
 181 {
 182         if (atomic_dec_and_test(&rt->rt6i_ref)) {
 183                 rt6_free_pcpu(rt);
 184                 dst_dev_put(&rt->dst);
 185                 dst_release(&rt->dst);
 186         }
 187 }
 188
 189 static void fib6_link_table(struct net *net, struct fib6_table *tb)
 190 {
 191         unsigned int h;
 192
 193         /*
 194          * Initialize table lock at a single place to give lockdep a key,
 195          * tables aren't visible prior to being linked to the list.
 196          */
 197         rwlock_init(&tb->tb6_lock);
 198
 199         h = tb->tb6_id & (FIB6_TABLE_HASHSZ - 1);
 200
 201         /*
 202          * No protection necessary, this is the only list mutatation
 203          * operation, tables never disappear once they exist.
 204          */
 205         hlist_add_head_rcu(&tb->tb6_hlist, &net->ipv6.fib_table_hash[h]);
 206 }
 207
 208 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
 209
 210 static struct fib6_table *fib6_alloc_table(struct net *net, u32 id)
 211 {
 212         struct fib6_table *table;
 213
 214         table = kzalloc(sizeof(*table), GFP_ATOMIC);
 215         if (table) {
 216                 table->tb6_id = id;
 217                 table->tb6_root.leaf = net->ipv6.ip6_null_entry;
 218                 table->tb6_root.fn_flags = RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
 219                 inet_peer_base_init(&table->tb6_peers);
 220         }
 221
 222         return table;
 223 }
 224
 225 struct fib6_table *fib6_new_table(struct net *net, u32 id)
 226 {
 227         struct fib6_table *tb;
 228
 229         if (id == 0)
 230                 id = RT6_TABLE_MAIN;
 231         tb = fib6_get_table(net, id);
 232         if (tb)
 233                 return tb;
 234
 235         tb = fib6_alloc_table(net, id);
 236         if (tb)
 237                 fib6_link_table(net, tb);
 238
 239         return tb;
 240 }
 241 EXPORT_SYMBOL_GPL(fib6_new_table);
 242
 243 struct fib6_table *fib6_get_table(struct net *net, u32 id)
 244 {
 245         struct fib6_table *tb;
 246         struct hlist_head *head;
 247         unsigned int h;
 248
 249         if (id == 0)
 250                 id = RT6_TABLE_MAIN;
 251         h = id & (FIB6_TABLE_HASHSZ - 1);
 252         rcu_read_lock();
 253         head = &net->ipv6.fib_table_hash[h];
 254         hlist_for_each_entry_rcu(tb, head, tb6_hlist) {
 255                 if (tb->tb6_id == id) {
 256                         rcu_read_unlock();
 257                         return tb;
 258                 }
 259         }
 260         rcu_read_unlock();
 261
 262         return NULL;
 263 }
 264 EXPORT_SYMBOL_GPL(fib6_get_table);
 265
 266 static void __net_init fib6_tables_init(struct net *net)
 267 {
 268         fib6_link_table(net, net->ipv6.fib6_main_tbl);
 269         fib6_link_table(net, net->ipv6.fib6_local_tbl);
 270 }
 271 #else
 272
 273 struct fib6_table *fib6_new_table(struct net *net, u32 id)
 274 {
 275         return fib6_get_table(net, id);
 276 }
 277
 278 struct fib6_table *fib6_get_table(struct net *net, u32 id)
 279 {
 280           return net->ipv6.fib6_main_tbl;
 281 }
 282
 283 struct dst_entry *fib6_rule_lookup(struct net *net, struct flowi6 *fl6,
 284                                    int flags, pol_lookup_t lookup)
 285 {
 286         struct rt6_info *rt;
 287
 288         rt = lookup(net, net->ipv6.fib6_main_tbl, fl6, flags);
 289         if (rt->dst.error == -EAGAIN) {
 290                 ip6_rt_put(rt);
 291                 rt = net->ipv6.ip6_null_entry;
 292                 dst_hold(&rt->dst);
 293         }
 294
 295         return &rt->dst;
 296 }
 297
 298 static void __net_init fib6_tables_init(struct net *net)
 299 {
 300         fib6_link_table(net, net->ipv6.fib6_main_tbl);
 301 }
 302
 303 #endif
 304
 305 static int fib6_dump_node(struct fib6_walker *w)
 306 {
 307         int res;
 308         struct rt6_info *rt;
 309
 310         for (rt = w->leaf; rt; rt = rt->dst.rt6_next) {
 311                 res = rt6_dump_route(rt, w->args);
 312                 if (res < 0) {
 313                         /* Frame is full, suspend walking */
 314                         w->leaf = rt;
 315                         return 1;
 316                 }
 317
 318                 /* Multipath routes are dumped in one route with the
 319                  * RTA_MULTIPATH attribute. Jump 'rt' to point to the
 320                  * last sibling of this route (no need to dump the
 321                  * sibling routes again)
 322                  */
 323                 if (rt->rt6i_nsiblings)
 324                         rt = list_last_entry(&rt->rt6i_siblings,
 325                                              struct rt6_info,
 326                                              rt6i_siblings);
 327         }
 328         w->leaf = NULL;
 329         return 0;
 330 }
 331
 332 static void fib6_dump_end(struct netlink_callback *cb)
 333 {
 334         struct net *net = sock_net(cb->skb->sk);
 335         struct fib6_walker *w = (void *)cb->args[2];
 336
 337         if (w) {
 338                 if (cb->args[4]) {
 339                         cb->args[4] = 0;
 340                         fib6_walker_unlink(net, w);
 341                 }
 342                 cb->args[2] = 0;
 343                 kfree(w);
 344         }
 345         cb->done = (void *)cb->args[3];
 346         cb->args[1] = 3;
 347 }
 348
 349 static int fib6_dump_done(struct netlink_callback *cb)
 350 {
 351         fib6_dump_end(cb);
 352         return cb->done ? cb->done(cb) : 0;
 353 }
 354
 355 static int fib6_dump_table(struct fib6_table *table, struct sk_buff *skb,
 356                            struct netlink_callback *cb)
 357 {
 358         struct net *net = sock_net(skb->sk);
 359         struct fib6_walker *w;
 360         int res;
 361
 362         w = (void *)cb->args[2];
 363         w->root = &table->tb6_root;
 364
 365         if (cb->args[4] == 0) {
 366                 w->count = 0;
 367                 w->skip = 0;
 368
 369                 read_lock_bh(&table->tb6_lock);
 370                 res = fib6_walk(net, w);
 371                 read_unlock_bh(&table->tb6_lock);
 372                 if (res > 0) {
 373                         cb->args[4] = 1;
 374                         cb->args[5] = w->root->fn_sernum;
 375                 }
 376         } else {
 377                 if (cb->args[5] != w->root->fn_sernum) {
 378                         /* Begin at the root if the tree changed */
 379                         cb->args[5] = w->root->fn_sernum;
 380                         w->state = FWS_INIT;
 381                         w->node = w->root;
 382                         w->skip = w->count;
 383                 } else
 384                         w->skip = 0;
 385
 386                 read_lock_bh(&table->tb6_lock);
 387                 res = fib6_walk_continue(w);
 388                 read_unlock_bh(&table->tb6_lock);
 389                 if (res <= 0) {
 390                         fib6_walker_unlink(net, w);
 391                         cb->args[4] = 0;
 392                 }
 393         }
 394
 395         return res;
 396 }
 397
 398 static int inet6_dump_fib(struct sk_buff *skb, struct netlink_callback *cb)
 399 {
 400         struct net *net = sock_net(skb->sk);
 401         unsigned int h, s_h;
 402         unsigned int e = 0, s_e;
 403         struct rt6_rtnl_dump_arg arg;
 404         struct fib6_walker *w;
 405         struct fib6_table *tb;
 406         struct hlist_head *head;
 407         int res = 0;
 408
 409         s_h = cb->args[0];
 410         s_e = cb->args[1];
 411
 412         w = (void *)cb->args[2];
 413         if (!w) {
 414                 /* New dump:
 415                  *
 416                  * 1. hook callback destructor.
 417                  */
 418                 cb->args[3] = (long)cb->done;
 419                 cb->done = fib6_dump_done;
 420
 421                 /*
 422                  * 2. allocate and initialize walker.
 423                  */
 424                 w = kzalloc(sizeof(*w), GFP_ATOMIC);
 425                 if (!w)
 426                         return -ENOMEM;
 427                 w->func = fib6_dump_node;
 428                 cb->args[2] = (long)w;
 429         }
 430
 431         arg.skb = skb;
 432         arg.cb = cb;
 433         arg.net = net;
 434         w->args = &arg;
 435
 436         rcu_read_lock();
 437         for (h = s_h; h < FIB6_TABLE_HASHSZ; h++, s_e = 0) {
 438                 e = 0;
 439                 head = &net->ipv6.fib_table_hash[h];
 440                 hlist_for_each_entry_rcu(tb, head, tb6_hlist) {
 441                         if (e < s_e)
 442                                 goto next;
 443                         res = fib6_dump_table(tb, skb, cb);
 444                         if (res != 0)
 445                                 goto out;
 446 next:
 447                         e++;
 448                 }
 449         }
 450 out:
 451         rcu_read_unlock();
 452         cb->args[1] = e;
 453         cb->args[0] = h;
 454
 455         res = res < 0 ? res : skb->len;
 456         if (res <= 0)
 457                 fib6_dump_end(cb);
 458         return res;
 459 }
 460
 461 /*
 462  *      Routing Table
 463  *
 464  *      return the appropriate node for a routing tree "add" operation
 465  *      by either creating and inserting or by returning an existing
 466  *      node.
 467  */
 468
 469 static struct fib6_node *fib6_add_1(struct fib6_node *root,
 470                                      struct in6_addr *addr, int plen,
 471                                      int offset, int allow_create,
 472                                      int replace_required, int sernum,
 473                                      struct netlink_ext_ack *extack)
 474 {
 475         struct fib6_node *fn, *in, *ln;
 476         struct fib6_node *pn = NULL;
 477         struct rt6key *key;
 478         int     bit;
 479         __be32  dir = 0;
 480
 481         RT6_TRACE("fib6_add_1\n");
 482
 483         /* insert node in tree */
 484
 485         fn = root;
 486
 487         do {
 488                 key = (struct rt6key *)((u8 *)fn->leaf + offset);
 489
 490                 /*
 491                  *      Prefix match
 492                  */
 493                 if (plen < fn->fn_bit ||
 494                     !ipv6_prefix_equal(&key->addr, addr, fn->fn_bit)) {
 495                         if (!allow_create) {
 496                                 if (replace_required) {
 497                                         NL_SET_ERR_MSG(extack,
 498                                                        "Can not replace route - no match found");
 499                                         pr_warn("Can't replace route, no match found\n");
 500                                         return ERR_PTR(-ENOENT);
 501                                 }
 502                                 pr_warn("NLM_F_CREATE should be set when creating new route\n");
 503                         }
 504                         goto insert_above;
 505                 }
 506
 507                 /*
 508                  *      Exact match ?
 509                  */
 510
 511                 if (plen == fn->fn_bit) {
 512                         /* clean up an intermediate node */
 513                         if (!(fn->fn_flags & RTN_RTINFO)) {
 514                                 rt6_release(fn->leaf);
 515                                 fn->leaf = NULL;
 516                         }
 517
 518                         fn->fn_sernum = sernum;
 519
 520                         return fn;
 521                 }
 522
 523                 /*
 524                  *      We have more bits to go
 525                  */
 526
 527                 /* Try to walk down on tree. */
 528                 fn->fn_sernum = sernum;
 529                 dir = addr_bit_set(addr, fn->fn_bit);
 530                 pn = fn;
 531                 fn = dir ? fn->right : fn->left;
 532         } while (fn);
 533
 534         if (!allow_create) {
 535                 /* We should not create new node because
 536                  * NLM_F_REPLACE was specified without NLM_F_CREATE
 537                  * I assume it is safe to require NLM_F_CREATE when
 538                  * REPLACE flag is used! Later we may want to remove the
 539                  * check for replace_required, because according
 540                  * to netlink specification, NLM_F_CREATE
 541                  * MUST be specified if new route is created.
 542                  * That would keep IPv6 consistent with IPv4
 543                  */
 544                 if (replace_required) {
 545                         NL_SET_ERR_MSG(extack,
 546                                        "Can not replace route - no match found");
 547                         pr_warn("Can't replace route, no match found\n");
 548                         return ERR_PTR(-ENOENT);
 549                 }
 550                 pr_warn("NLM_F_CREATE should be set when creating new route\n");
 551         }
 552         /*
 553          *      We walked to the bottom of tree.
 554          *      Create new leaf node without children.
 555          */
 556
 557         ln = node_alloc();
 558
 559         if (!ln)
 560                 return ERR_PTR(-ENOMEM);
 561         ln->fn_bit = plen;
 562
 563         ln->parent = pn;
 564         ln->fn_sernum = sernum;
 565
 566         if (dir)
 567                 pn->right = ln;
 568         else
 569                 pn->left  = ln;
 570
 571         return ln;
 572
 573
 574 insert_above:
 575         /*
 576          * split since we don't have a common prefix anymore or
 577          * we have a less significant route.
 578          * we've to insert an intermediate node on the list
 579          * this new node will point to the one we need to create
 580          * and the current
 581          */
 582
 583         pn = fn->parent;
 584
 585         /* find 1st bit in difference between the 2 addrs.
 586
 587            See comment in __ipv6_addr_diff: bit may be an invalid value,
 588            but if it is >= plen, the value is ignored in any case.
 589          */
 590
 591         bit = __ipv6_addr_diff(addr, &key->addr, sizeof(*addr));
 592
 593         /*
 594          *              (intermediate)[in]
 595          *                /        \
 596          *      (new leaf node)[ln] (old node)[fn]
 597          */
 598         if (plen > bit) {
 599                 in = node_alloc();
 600                 ln = node_alloc();
 601
 602                 if (!in || !ln) {
 603                         if (in)
 604                                 node_free(in);
 605                         if (ln)
 606                                 node_free(ln);
 607                         return ERR_PTR(-ENOMEM);
 608                 }
 609
 610                 /*
 611                  * new intermediate node.
 612                  * RTN_RTINFO will
 613                  * be off since that an address that chooses one of
 614                  * the branches would not match less specific routes
 615                  * in the other branch
 616                  */
 617
 618                 in->fn_bit = bit;
 619
 620                 in->parent = pn;
 621                 in->leaf = fn->leaf;
 622                 atomic_inc(&in->leaf->rt6i_ref);
 623
 624                 in->fn_sernum = sernum;
 625
 626                 /* update parent pointer */
 627                 if (dir)
 628                         pn->right = in;
 629                 else
 630                         pn->left  = in;
 631
 632                 ln->fn_bit = plen;
 633
 634                 ln->parent = in;
 635                 fn->parent = in;
 636
 637                 ln->fn_sernum = sernum;
 638
 639                 if (addr_bit_set(addr, bit)) {
 640                         in->right = ln;
 641                         in->left  = fn;
 642                 } else {
 643                         in->left  = ln;
 644                         in->right = fn;
 645                 }
 646         } else { /* plen <= bit */
 647
 648                 /*
 649                  *              (new leaf node)[ln]
 650                  *                /        \
 651                  *           (old node)[fn] NULL
 652                  */
 653
 654                 ln = node_alloc();
 655
 656                 if (!ln)
 657                         return ERR_PTR(-ENOMEM);
 658
 659                 ln->fn_bit = plen;
 660
 661                 ln->parent = pn;
 662
 663                 ln->fn_sernum = sernum;
 664
 665                 if (dir)
 666                         pn->right = ln;
 667                 else
 668                         pn->left  = ln;
 669
 670                 if (addr_bit_set(&key->addr, plen))
 671                         ln->right = fn;
 672                 else
 673                         ln->left  = fn;
 674
 675                 fn->parent = ln;
 676         }
 677         return ln;
 678 }
 679
 680 static bool rt6_qualify_for_ecmp(struct rt6_info *rt)
 681 {
 682         return (rt->rt6i_flags & (RTF_GATEWAY|RTF_ADDRCONF|RTF_DYNAMIC)) ==
 683                RTF_GATEWAY;
 684 }
 685
 686 static void fib6_copy_metrics(u32 *mp, const struct mx6_config *mxc)
 687 {
 688         int i;
 689
 690         for (i = 0; i < RTAX_MAX; i++) {
 691                 if (test_bit(i, mxc->mx_valid))
 692                         mp[i] = mxc->mx[i];
 693         }
 694 }
 695
 696 static int fib6_commit_metrics(struct dst_entry *dst, struct mx6_config *mxc)
 697 {
 698         if (!mxc->mx)
 699                 return 0;
 700
 701         if (dst->flags & DST_HOST) {
 702                 u32 *mp = dst_metrics_write_ptr(dst);
 703
 704                 if (unlikely(!mp))
 705                         return -ENOMEM;
 706
 707                 fib6_copy_metrics(mp, mxc);
 708         } else {
 709                 dst_init_metrics(dst, mxc->mx, false);
 710
 711                 /* We've stolen mx now. */
 712                 mxc->mx = NULL;
 713         }
 714
 715         return 0;
 716 }
 717
 718 static void fib6_purge_rt(struct rt6_info *rt, struct fib6_node *fn,
 719                           struct net *net)
 720 {
 721         if (atomic_read(&rt->rt6i_ref) != 1) {
 722                 /* This route is used as dummy address holder in some split
 723                  * nodes. It is not leaked, but it still holds other resources,
 724                  * which must be released in time. So, scan ascendant nodes
 725                  * and replace dummy references to this route with references
 726                  * to still alive ones.
 727                  */
 728                 while (fn) {
 729                         if (!(fn->fn_flags & RTN_RTINFO) && fn->leaf == rt) {
 730                                 fn->leaf = fib6_find_prefix(net, fn);
 731                                 atomic_inc(&fn->leaf->rt6i_ref);
 732                                 rt6_release(rt);
 733                         }
 734                         fn = fn->parent;
 735                 }
 736                 /* No more references are possible at this point. */
 737                 BUG_ON(atomic_read(&rt->rt6i_ref) != 1);
 738         }
 739 }
 740
 741 /*
 742  *      Insert routing information in a node.
 743  */
 744
 745 static int fib6_add_rt2node(struct fib6_node *fn, struct rt6_info *rt,
 746                             struct nl_info *info, struct mx6_config *mxc)
 747 {
 748         struct rt6_info *iter = NULL;
 749         struct rt6_info **ins;
 750         struct rt6_info **fallback_ins = NULL;
 751         int replace = (info->nlh &&
 752                        (info->nlh->nlmsg_flags & NLM_F_REPLACE));
 753         int add = (!info->nlh ||
 754                    (info->nlh->nlmsg_flags & NLM_F_CREATE));
 755         int found = 0;
 756         bool rt_can_ecmp = rt6_qualify_for_ecmp(rt);
 757         u16 nlflags = NLM_F_EXCL;
 758         int err;
 759
 760         if (info->nlh && (info->nlh->nlmsg_flags & NLM_F_APPEND))
 761                 nlflags |= NLM_F_APPEND;
 762
 763         ins = &fn->leaf;
 764
 765         for (iter = fn->leaf; iter; iter = iter->dst.rt6_next) {
 766                 /*
 767                  *      Search for duplicates
 768                  */
 769
 770                 if (iter->rt6i_metric == rt->rt6i_metric) {
 771                         /*
 772                          *      Same priority level
 773                          */
 774                         if (info->nlh &&
 775                             (info->nlh->nlmsg_flags & NLM_F_EXCL))
 776                                 return -EEXIST;
 777
 778                         nlflags &= ~NLM_F_EXCL;
 779                         if (replace) {
 780                                 if (rt_can_ecmp == rt6_qualify_for_ecmp(iter)) {
 781                                         found++;
 782                                         break;
 783                                 }
 784                                 if (rt_can_ecmp)
 785                                         fallback_ins = fallback_ins ?: ins;
 786                                 goto next_iter;
 787                         }
 788
 789                         if (rt6_duplicate_nexthop(iter, rt)) {
 790                                 if (rt->rt6i_nsiblings)
 791                                         rt->rt6i_nsiblings = 0;
 792                                 if (!(iter->rt6i_flags & RTF_EXPIRES))
 793                                         return -EEXIST;
 794                                 if (!(rt->rt6i_flags & RTF_EXPIRES))
 795                                         rt6_clean_expires(iter);
 796                                 else
 797                                         rt6_set_expires(iter, rt->dst.expires);
 798                                 iter->rt6i_pmtu = rt->rt6i_pmtu;
 799                                 return -EEXIST;
 800                         }
 801                         /* If we have the same destination and the same metric,
 802                          * but not the same gateway, then the route we try to
 803                          * add is sibling to this route, increment our counter
 804                          * of siblings, and later we will add our route to the
 805                          * list.
 806                          * Only static routes (which don't have flag
 807                          * RTF_EXPIRES) are used for ECMPv6.
 808                          *
 809                          * To avoid long list, we only had siblings if the
 810                          * route have a gateway.
 811                          */
 812                         if (rt_can_ecmp &&
 813                             rt6_qualify_for_ecmp(iter))
 814                                 rt->rt6i_nsiblings++;
 815                 }
 816
 817                 if (iter->rt6i_metric > rt->rt6i_metric)
 818                         break;
 819
 820 next_iter:
 821                 ins = &iter->dst.rt6_next;
 822         }
 823
 824         if (fallback_ins && !found) {
 825                 /* No ECMP-able route found, replace first non-ECMP one */
 826                 ins = fallback_ins;
 827                 iter = *ins;
 828                 found++;
 829         }
 830
 831         /* Reset round-robin state, if necessary */
 832         if (ins == &fn->leaf)
 833                 fn->rr_ptr = NULL;
 834
 835         /* Link this route to others same route. */
 836         if (rt->rt6i_nsiblings) {
 837                 unsigned int rt6i_nsiblings;
 838                 struct rt6_info *sibling, *temp_sibling;
 839
 840                 /* Find the first route that have the same metric */
 841                 sibling = fn->leaf;
 842                 while (sibling) {
 843                         if (sibling->rt6i_metric == rt->rt6i_metric &&
 844                             rt6_qualify_for_ecmp(sibling)) {
 845                                 list_add_tail(&rt->rt6i_siblings,
 846                                               &sibling->rt6i_siblings);
 847                                 break;
 848                         }
 849                         sibling = sibling->dst.rt6_next;
 850                 }
 851                 /* For each sibling in the list, increment the counter of
 852                  * siblings. BUG() if counters does not match, list of siblings
 853                  * is broken!
 854                  */
 855                 rt6i_nsiblings = 0;
 856                 list_for_each_entry_safe(sibling, temp_sibling,
 857                                          &rt->rt6i_siblings, rt6i_siblings) {
 858                         sibling->rt6i_nsiblings++;
 859                         BUG_ON(sibling->rt6i_nsiblings != rt->rt6i_nsiblings);
 860                         rt6i_nsiblings++;
 861                 }
 862                 BUG_ON(rt6i_nsiblings != rt->rt6i_nsiblings);
 863         }
 864
 865         /*
 866          *      insert node
 867          */
 868         if (!replace) {
 869                 if (!add)
 870                         pr_warn("NLM_F_CREATE should be set when creating new route\n");
 871
 872 add:
 873                 nlflags |= NLM_F_CREATE;
 874                 err = fib6_commit_metrics(&rt->dst, mxc);
 875                 if (err)
 876                         return err;
 877
 878                 rt->dst.rt6_next = iter;
 879                 *ins = rt;
 880                 rt->rt6i_node = fn;
 881                 atomic_inc(&rt->rt6i_ref);
 882                 if (!info->skip_notify)
 883                         inet6_rt_notify(RTM_NEWROUTE, rt, info, nlflags);
 884                 info->nl_net->ipv6.rt6_stats->fib_rt_entries++;
 885
 886                 if (!(fn->fn_flags & RTN_RTINFO)) {
 887                         info->nl_net->ipv6.rt6_stats->fib_route_nodes++;
 888                         fn->fn_flags |= RTN_RTINFO;
 889                 }
 890
 891         } else {
 892                 int nsiblings;
 893
 894                 if (!found) {
 895                         if (add)
 896                                 goto add;
 897                         pr_warn("NLM_F_REPLACE set, but no existing node found!\n");
 898                         return -ENOENT;
 899                 }
 900
 901                 err = fib6_commit_metrics(&rt->dst, mxc);
 902                 if (err)
 903                         return err;
 904
 905                 *ins = rt;
 906                 rt->rt6i_node = fn;
 907                 rt->dst.rt6_next = iter->dst.rt6_next;
 908                 atomic_inc(&rt->rt6i_ref);
 909                 if (!info->skip_notify)
 910                         inet6_rt_notify(RTM_NEWROUTE, rt, info, NLM_F_REPLACE);
 911                 if (!(fn->fn_flags & RTN_RTINFO)) {
 912                         info->nl_net->ipv6.rt6_stats->fib_route_nodes++;
 913                         fn->fn_flags |= RTN_RTINFO;
 914                 }
 915                 nsiblings = iter->rt6i_nsiblings;
 916                 fib6_purge_rt(iter, fn, info->nl_net);
 917                 if (fn->rr_ptr == iter)
 918                         fn->rr_ptr = NULL;
 919                 rt6_release(iter);
 920
 921                 if (nsiblings) {
 922                         /* Replacing an ECMP route, remove all siblings */
 923                         ins = &rt->dst.rt6_next;
 924                         iter = *ins;
 925                         while (iter) {
 926                                 if (iter->rt6i_metric > rt->rt6i_metric)
 927                                         break;
 928                                 if (rt6_qualify_for_ecmp(iter)) {
 929                                         *ins = iter->dst.rt6_next;
 930                                         fib6_purge_rt(iter, fn, info->nl_net);
 931                                         if (fn->rr_ptr == iter)
 932                                                 fn->rr_ptr = NULL;
 933                                         rt6_release(iter);
 934                                         nsiblings--;
 935                                 } else {
 936                                         ins = &iter->dst.rt6_next;
 937                                 }
 938                                 iter = *ins;
 939                         }
 940                         WARN_ON(nsiblings != 0);
 941                 }
 942         }
 943
 944         return 0;
 945 }
 946
 947 static void fib6_start_gc(struct net *net, struct rt6_info *rt)
 948 {
 949         if (!timer_pending(&net->ipv6.ip6_fib_timer) &&
 950             (rt->rt6i_flags & (RTF_EXPIRES | RTF_CACHE)))
 951                 mod_timer(&net->ipv6.ip6_fib_timer,
 952                           jiffies + net->ipv6.sysctl.ip6_rt_gc_interval);
 953 }
 954
 955 void fib6_force_start_gc(struct net *net)
 956 {
 957         if (!timer_pending(&net->ipv6.ip6_fib_timer))
 958                 mod_timer(&net->ipv6.ip6_fib_timer,
 959                           jiffies + net->ipv6.sysctl.ip6_rt_gc_interval);
 960 }
 961
 962 /*
 963  *      Add routing information to the routing tree.
 964  *      <destination addr>/<source addr>
 965  *      with source addr info in sub-trees
 966  */
 967
 968 int fib6_add(struct fib6_node *root, struct rt6_info *rt,
 969              struct nl_info *info, struct mx6_config *mxc,
 970              struct netlink_ext_ack *extack)
 971 {
 972         struct fib6_node *fn, *pn = NULL;
 973         int err = -ENOMEM;
 974         int allow_create = 1;
 975         int replace_required = 0;
 976         int sernum = fib6_new_sernum(info->nl_net);
 977
 978         if (WARN_ON_ONCE(!atomic_read(&rt->dst.__refcnt)))
 979                 return -EINVAL;
 980
 981         if (info->nlh) {
 982                 if (!(info->nlh->nlmsg_flags & NLM_F_CREATE))
 983                         allow_create = 0;
 984                 if (info->nlh->nlmsg_flags & NLM_F_REPLACE)
 985                         replace_required = 1;
 986         }
 987         if (!allow_create && !replace_required)
 988                 pr_warn("RTM_NEWROUTE with no NLM_F_CREATE or NLM_F_REPLACE\n");
 989
 990         fn = fib6_add_1(root, &rt->rt6i_dst.addr, rt->rt6i_dst.plen,
 991                         offsetof(struct rt6_info, rt6i_dst), allow_create,
 992                         replace_required, sernum, extack);
 993         if (IS_ERR(fn)) {
 994                 err = PTR_ERR(fn);
 995                 fn = NULL;
 996                 goto out;
 997         }
 998
 999         pn = fn;
1000
1001 #ifdef CONFIG_IPV6_SUBTREES
1002         if (rt->rt6i_src.plen) {
1003                 struct fib6_node *sn;
1004
1005                 if (!fn->subtree) {
1006                         struct fib6_node *sfn;
1007
1008                         /*
1009                          * Create subtree.
1010                          *
1011                          *              fn[main tree]
1012                          *              |
1013                          *              sfn[subtree root]
1014                          *                 \
1015                          *                  sn[new leaf node]
1016                          */
1017
1018                         /* Create subtree root node */
1019                         sfn = node_alloc();
1020                         if (!sfn)
1021                                 goto failure;
1022
1023                         sfn->leaf = info->nl_net->ipv6.ip6_null_entry;
1024                         atomic_inc(&info->nl_net->ipv6.ip6_null_entry->rt6i_ref);
1025                         sfn->fn_flags = RTN_ROOT;
1026                         sfn->fn_sernum = sernum;
1027
1028                         /* Now add the first leaf node to new subtree */
1029
1030                         sn = fib6_add_1(sfn, &rt->rt6i_src.addr,
1031                                         rt->rt6i_src.plen,
1032                                         offsetof(struct rt6_info, rt6i_src),
1033                                         allow_create, replace_required, sernum,
1034                                         extack);
1035
1036                         if (IS_ERR(sn)) {
1037                                 /* If it is failed, discard just allocated
1038                                    root, and then (in failure) stale node
1039                                    in main tree.
1040                                  */
1041                                 node_free(sfn);
1042                                 err = PTR_ERR(sn);
1043                                 goto failure;
1044                         }
1045
1046                         /* Now link new subtree to main tree */
1047                         sfn->parent = fn;
1048                         fn->subtree = sfn;
1049                 } else {
1050                         sn = fib6_add_1(fn->subtree, &rt->rt6i_src.addr,
1051                                         rt->rt6i_src.plen,
1052                                         offsetof(struct rt6_info, rt6i_src),
1053                                         allow_create, replace_required, sernum,
1054                                         extack);
1055
1056                         if (IS_ERR(sn)) {
1057                                 err = PTR_ERR(sn);
1058                                 goto failure;
1059                         }
1060                 }
1061
1062                 if (!fn->leaf) {
1063                         fn->leaf = rt;
1064                         atomic_inc(&rt->rt6i_ref);
1065                 }
1066                 fn = sn;
1067         }
1068 #endif
1069
1070         err = fib6_add_rt2node(fn, rt, info, mxc);
1071         if (!err) {
1072                 fib6_start_gc(info->nl_net, rt);
1073                 if (!(rt->rt6i_flags & RTF_CACHE))
1074                         fib6_prune_clones(info->nl_net, pn);
1075         }
1076
1077 out:
1078         if (err) {
1079 #ifdef CONFIG_IPV6_SUBTREES
1080                 /*
1081                  * If fib6_add_1 has cleared the old leaf pointer in the
1082                  * super-tree leaf node we have to find a new one for it.
1083                  */
1084                 if (pn != fn && pn->leaf == rt) {
1085                         pn->leaf = NULL;
1086                         atomic_dec(&rt->rt6i_ref);
1087                 }
1088                 if (pn != fn && !pn->leaf && !(pn->fn_flags & RTN_RTINFO)) {
1089                         pn->leaf = fib6_find_prefix(info->nl_net, pn);
1090 #if RT6_DEBUG >= 2
1091                         if (!pn->leaf) {
1092                                 WARN_ON(pn->leaf == NULL);
1093                                 pn->leaf = info->nl_net->ipv6.ip6_null_entry;
1094                         }
1095 #endif
1096                         atomic_inc(&pn->leaf->rt6i_ref);
1097                 }
1098 #endif
1099                 goto failure;
1100         }
1101         return err;
1102
1103 failure:
1104         /* fn->leaf could be NULL if fn is an intermediate node and we
1105          * failed to add the new route to it in both subtree creation
1106          * failure and fib6_add_rt2node() failure case.
1107          * In both cases, fib6_repair_tree() should be called to fix
1108          * fn->leaf.
1109          */
1110         if (fn && !(fn->fn_flags & (RTN_RTINFO|RTN_ROOT)))
1111                 fib6_repair_tree(info->nl_net, fn);
1112         /* Always release dst as dst->__refcnt is guaranteed
1113          * to be taken before entering this function
1114          */
1115         dst_release_immediate(&rt->dst);
1116         return err;
1117 }
1118
1119 /*
1120  *      Routing tree lookup
1121  *
1122  */
1123
1124 struct lookup_args {
1125         int                     offset;         /* key offset on rt6_info       */
1126         const struct in6_addr   *addr;          /* search key                   */
1127 };
1128
1129 static struct fib6_node *fib6_lookup_1(struct fib6_node *root,
1130                                        struct lookup_args *args)
1131 {
1132         struct fib6_node *fn;
1133         __be32 dir;
1134
1135         if (unlikely(args->offset == 0))
1136                 return NULL;
1137
1138         /*
1139          *      Descend on a tree
1140          */
1141
1142         fn = root;
1143
1144         for (;;) {
1145                 struct fib6_node *next;
1146
1147                 dir = addr_bit_set(args->addr, fn->fn_bit);
1148
1149                 next = dir ? fn->right : fn->left;
1150
1151                 if (next) {
1152                         fn = next;
1153                         continue;
1154                 }
1155                 break;
1156         }
1157
1158         while (fn) {
1159                 if (FIB6_SUBTREE(fn) || fn->fn_flags & RTN_RTINFO) {
1160                         struct rt6key *key;
1161
1162                         key = (struct rt6key *) ((u8 *) fn->leaf +
1163                                                  args->offset);
1164
1165                         if (ipv6_prefix_equal(&key->addr, args->addr, key->plen)) {
1166 #ifdef CONFIG_IPV6_SUBTREES
1167                                 if (fn->subtree) {
1168                                         struct fib6_node *sfn;
1169                                         sfn = fib6_lookup_1(fn->subtree,
1170                                                             args + 1);
1171                                         if (!sfn)
1172                                                 goto backtrack;
1173                                         fn = sfn;
1174                                 }
1175 #endif
1176                                 if (fn->fn_flags & RTN_RTINFO)
1177                                         return fn;
1178                         }
1179                 }
1180 #ifdef CONFIG_IPV6_SUBTREES
1181 backtrack:
1182 #endif
1183                 if (fn->fn_flags & RTN_ROOT)
1184                         break;
1185
1186                 fn = fn->parent;
1187         }
1188
1189         return NULL;
1190 }
1191
1192 struct fib6_node *fib6_lookup(struct fib6_node *root, const struct in6_addr *daddr,
1193                               const struct in6_addr *saddr)
1194 {
1195         struct fib6_node *fn;
1196         struct lookup_args args[] = {
1197                 {
1198                         .offset = offsetof(struct rt6_info, rt6i_dst),
1199                         .addr = daddr,
1200                 },
1201 #ifdef CONFIG_IPV6_SUBTREES
1202                 {
1203                         .offset = offsetof(struct rt6_info, rt6i_src),
1204                         .addr = saddr,
1205                 },
1206 #endif
1207                 {
1208                         .offset = 0,    /* sentinel */
1209                 }
1210         };
1211
1212         fn = fib6_lookup_1(root, daddr ? args : args + 1);
1213         if (!fn || fn->fn_flags & RTN_TL_ROOT)
1214                 fn = root;
1215
1216         return fn;
1217 }
1218
1219 /*
1220  *      Get node with specified destination prefix (and source prefix,
1221  *      if subtrees are used)
1222  */
1223
1224
1225 static struct fib6_node *fib6_locate_1(struct fib6_node *root,
1226                                        const struct in6_addr *addr,
1227                                        int plen, int offset)
1228 {
1229         struct fib6_node *fn;
1230
1231         for (fn = root; fn ; ) {
1232                 struct rt6key *key = (struct rt6key *)((u8 *)fn->leaf + offset);
1233
1234                 /*
1235                  *      Prefix match
1236                  */
1237                 if (plen < fn->fn_bit ||
1238                     !ipv6_prefix_equal(&key->addr, addr, fn->fn_bit))
1239                         return NULL;
1240
1241                 if (plen == fn->fn_bit)
1242                         return fn;
1243
1244                 /*
1245                  *      We have more bits to go
1246                  */
1247                 if (addr_bit_set(addr, fn->fn_bit))
1248                         fn = fn->right;
1249                 else
1250                         fn = fn->left;
1251         }
1252         return NULL;
1253 }
1254
1255 struct fib6_node *fib6_locate(struct fib6_node *root,
1256                               const struct in6_addr *daddr, int dst_len,
1257                               const struct in6_addr *saddr, int src_len)
1258 {
1259         struct fib6_node *fn;
1260
1261         fn = fib6_locate_1(root, daddr, dst_len,
1262                            offsetof(struct rt6_info, rt6i_dst));
1263
1264 #ifdef CONFIG_IPV6_SUBTREES
1265         if (src_len) {
1266                 WARN_ON(saddr == NULL);
1267                 if (fn && fn->subtree)
1268                         fn = fib6_locate_1(fn->subtree, saddr, src_len,
1269                                            offsetof(struct rt6_info, rt6i_src));
1270         }
1271 #endif
1272
1273         if (fn && fn->fn_flags & RTN_RTINFO)
1274                 return fn;
1275
1276         return NULL;
1277 }
1278
1279
1280 /*
1281  *      Deletion
1282  *
1283  */
1284
1285 static struct rt6_info *fib6_find_prefix(struct net *net, struct fib6_node *fn)
1286 {
1287         if (fn->fn_flags & RTN_ROOT)
1288                 return net->ipv6.ip6_null_entry;
1289
1290         while (fn) {
1291                 if (fn->left)
1292                         return fn->left->leaf;
1293                 if (fn->right)
1294                         return fn->right->leaf;
1295
1296                 fn = FIB6_SUBTREE(fn);
1297         }
1298         return NULL;
1299 }
1300
1301 /*
1302  *      Called to trim the tree of intermediate nodes when possible. "fn"
1303  *      is the node we want to try and remove.
1304  */
1305
1306 static struct fib6_node *fib6_repair_tree(struct net *net,
1307                                            struct fib6_node *fn)
1308 {
1309         int children;
1310         int nstate;
1311         struct fib6_node *child, *pn;
1312         struct fib6_walker *w;
1313         int iter = 0;
1314
1315         for (;;) {
1316                 RT6_TRACE("fixing tree: plen=%d iter=%d\n", fn->fn_bit, iter);
1317                 iter++;
1318
1319                 WARN_ON(fn->fn_flags & RTN_RTINFO);
1320                 WARN_ON(fn->fn_flags & RTN_TL_ROOT);
1321                 WARN_ON(fn->leaf);
1322
1323                 children = 0;
1324                 child = NULL;
1325                 if (fn->right)
1326                         child = fn->right, children |= 1;
1327                 if (fn->left)
1328                         child = fn->left, children |= 2;
1329
1330                 if (children == 3 || FIB6_SUBTREE(fn)
1331 #ifdef CONFIG_IPV6_SUBTREES
1332                     /* Subtree root (i.e. fn) may have one child */
1333                     || (children && fn->fn_flags & RTN_ROOT)
1334 #endif
1335                     ) {
1336                         fn->leaf = fib6_find_prefix(net, fn);
1337 #if RT6_DEBUG >= 2
1338                         if (!fn->leaf) {
1339                                 WARN_ON(!fn->leaf);
1340                                 fn->leaf = net->ipv6.ip6_null_entry;
1341                         }
1342 #endif
1343                         atomic_inc(&fn->leaf->rt6i_ref);
1344                         return fn->parent;
1345                 }
1346
1347                 pn = fn->parent;
1348 #ifdef CONFIG_IPV6_SUBTREES
1349                 if (FIB6_SUBTREE(pn) == fn) {
1350                         WARN_ON(!(fn->fn_flags & RTN_ROOT));
1351                         FIB6_SUBTREE(pn) = NULL;
1352                         nstate = FWS_L;
1353                 } else {
1354                         WARN_ON(fn->fn_flags & RTN_ROOT);
1355 #endif
1356                         if (pn->right == fn)
1357                                 pn->right = child;
1358                         else if (pn->left == fn)
1359                                 pn->left = child;
1360 #if RT6_DEBUG >= 2
1361                         else
1362                                 WARN_ON(1);
1363 #endif
1364                         if (child)
1365                                 child->parent = pn;
1366                         nstate = FWS_R;
1367 #ifdef CONFIG_IPV6_SUBTREES
1368                 }
1369 #endif
1370
1371                 read_lock(&net->ipv6.fib6_walker_lock);
1372                 FOR_WALKERS(net, w) {
1373                         if (!child) {
1374                                 if (w->root == fn) {
1375                                         w->root = w->node = NULL;
1376                                         RT6_TRACE("W %p adjusted by delroot 1\n", w);
1377                                 } else if (w->node == fn) {
1378                                         RT6_TRACE("W %p adjusted by delnode 1, s=%d/%d\n", w, w->state, nstate);
1379                                         w->node = pn;
1380                                         w->state = nstate;
1381                                 }
1382                         } else {
1383                                 if (w->root == fn) {
1384                                         w->root = child;
1385                                         RT6_TRACE("W %p adjusted by delroot 2\n", w);
1386                                 }
1387                                 if (w->node == fn) {
1388                                         w->node = child;
1389                                         if (children&2) {
1390                                                 RT6_TRACE("W %p adjusted by delnode 2, s=%d\n", w, w->state);
1391                                                 w->state = w->state >= FWS_R ? FWS_U : FWS_INIT;
1392                                         } else {
1393                                                 RT6_TRACE("W %p adjusted by delnode 2, s=%d\n", w, w->state);
1394                                                 w->state = w->state >= FWS_C ? FWS_U : FWS_INIT;
1395                                         }
1396                                 }
1397                         }
1398                 }
1399                 read_unlock(&net->ipv6.fib6_walker_lock);
1400
1401                 node_free(fn);
1402                 if (pn->fn_flags & RTN_RTINFO || FIB6_SUBTREE(pn))
1403                         return pn;
1404
1405                 rt6_release(pn->leaf);
1406                 pn->leaf = NULL;
1407                 fn = pn;
1408         }
1409 }
1410
1411 static void fib6_del_route(struct fib6_node *fn, struct rt6_info **rtp,
1412                            struct nl_info *info)
1413 {
1414         struct fib6_walker *w;
1415         struct rt6_info *rt = *rtp;
1416         struct net *net = info->nl_net;
1417
1418         RT6_TRACE("fib6_del_route\n");
1419
1420         /* Unlink it */
1421         *rtp = rt->dst.rt6_next;
1422         rt->rt6i_node = NULL;
1423         net->ipv6.rt6_stats->fib_rt_entries--;
1424         net->ipv6.rt6_stats->fib_discarded_routes++;
1425
1426         /* Reset round-robin state, if necessary */
1427         if (fn->rr_ptr == rt)
1428                 fn->rr_ptr = NULL;
1429
1430         /* Remove this entry from other siblings */
1431         if (rt->rt6i_nsiblings) {
1432                 struct rt6_info *sibling, *next_sibling;
1433
1434                 list_for_each_entry_safe(sibling, next_sibling,
1435                                          &rt->rt6i_siblings, rt6i_siblings)
1436                         sibling->rt6i_nsiblings--;
1437                 rt->rt6i_nsiblings = 0;
1438                 list_del_init(&rt->rt6i_siblings);
1439         }
1440
1441         /* Adjust walkers */
1442         read_lock(&net->ipv6.fib6_walker_lock);
1443         FOR_WALKERS(net, w) {
1444                 if (w->state == FWS_C && w->leaf == rt) {
1445                         RT6_TRACE("walker %p adjusted by delroute\n", w);
1446                         w->leaf = rt->dst.rt6_next;
1447                         if (!w->leaf)
1448                                 w->state = FWS_U;
1449                 }
1450         }
1451         read_unlock(&net->ipv6.fib6_walker_lock);
1452
1453         rt->dst.rt6_next = NULL;
1454
1455         /* If it was last route, expunge its radix tree node */
1456         if (!fn->leaf) {
1457                 fn->fn_flags &= ~RTN_RTINFO;
1458                 net->ipv6.rt6_stats->fib_route_nodes--;
1459                 fn = fib6_repair_tree(net, fn);
1460         }
1461
1462         fib6_purge_rt(rt, fn, net);
1463
1464         if (!info->skip_notify)
1465                 inet6_rt_notify(RTM_DELROUTE, rt, info, 0);
1466         rt6_release(rt);
1467 }
1468
1469 int fib6_del(struct rt6_info *rt, struct nl_info *info)
1470 {
1471         struct net *net = info->nl_net;
1472         struct fib6_node *fn = rt->rt6i_node;
1473         struct rt6_info **rtp;
1474
1475 #if RT6_DEBUG >= 2
1476         if (rt->dst.obsolete > 0) {
1477                 WARN_ON(fn);
1478                 return -ENOENT;
1479         }
1480 #endif
1481         if (!fn || rt == net->ipv6.ip6_null_entry)
1482                 return -ENOENT;
1483
1484         WARN_ON(!(fn->fn_flags & RTN_RTINFO));
1485
1486         if (!(rt->rt6i_flags & RTF_CACHE)) {
1487                 struct fib6_node *pn = fn;
1488 #ifdef CONFIG_IPV6_SUBTREES
1489                 /* clones of this route might be in another subtree */
1490                 if (rt->rt6i_src.plen) {
1491                         while (!(pn->fn_flags & RTN_ROOT))
1492                                 pn = pn->parent;
1493                         pn = pn->parent;
1494                 }
1495 #endif
1496                 fib6_prune_clones(info->nl_net, pn);
1497         }
1498
1499         /*
1500          *      Walk the leaf entries looking for ourself
1501          */
1502
1503         for (rtp = &fn->leaf; *rtp; rtp = &(*rtp)->dst.rt6_next) {
1504                 if (*rtp == rt) {
1505                         fib6_del_route(fn, rtp, info);
1506                         return 0;
1507                 }
1508         }
1509         return -ENOENT;
1510 }
1511
1512 /*
1513  *      Tree traversal function.
1514  *
1515  *      Certainly, it is not interrupt safe.
1516  *      However, it is internally reenterable wrt itself and fib6_add/fib6_del.
1517  *      It means, that we can modify tree during walking
1518  *      and use this function for garbage collection, clone pruning,
1519  *      cleaning tree when a device goes down etc. etc.
1520  *
1521  *      It guarantees that every node will be traversed,
1522  *      and that it will be traversed only once.
1523  *
1524  *      Callback function w->func may return:
1525  *      0 -> continue walking.
1526  *      positive value -> walking is suspended (used by tree dumps,
1527  *      and probably by gc, if it will be split to several slices)
1528  *      negative value -> terminate walking.
1529  *
1530  *      The function itself returns:
1531  *      0   -> walk is complete.
1532  *      >0  -> walk is incomplete (i.e. suspended)
1533  *      <0  -> walk is terminated by an error.
1534  */
1535
1536 static int fib6_walk_continue(struct fib6_walker *w)
1537 {
1538         struct fib6_node *fn, *pn;
1539
1540         for (;;) {
1541                 fn = w->node;
1542                 if (!fn)
1543                         return 0;
1544
1545                 if (w->prune && fn != w->root &&
1546                     fn->fn_flags & RTN_RTINFO && w->state < FWS_C) {
1547                         w->state = FWS_C;
1548                         w->leaf = fn->leaf;
1549                 }
1550                 switch (w->state) {
1551 #ifdef CONFIG_IPV6_SUBTREES
1552                 case FWS_S:
1553                         if (FIB6_SUBTREE(fn)) {
1554                                 w->node = FIB6_SUBTREE(fn);
1555                                 continue;
1556                         }
1557                         w->state = FWS_L;
1558 #endif
1559                 case FWS_L:
1560                         if (fn->left) {
1561                                 w->node = fn->left;
1562                                 w->state = FWS_INIT;
1563                                 continue;
1564                         }
1565                         w->state = FWS_R;
1566                 case FWS_R:
1567                         if (fn->right) {
1568                                 w->node = fn->right;
1569                                 w->state = FWS_INIT;
1570                                 continue;
1571                         }
1572                         w->state = FWS_C;
1573                         w->leaf = fn->leaf;
1574                 case FWS_C:
1575                         if (w->leaf && fn->fn_flags & RTN_RTINFO) {
1576                                 int err;
1577
1578                                 if (w->skip) {
1579                                         w->skip--;
1580                                         goto skip;
1581                                 }
1582
1583                                 err = w->func(w);
1584                                 if (err)
1585                                         return err;
1586
1587                                 w->count++;
1588                                 continue;
1589                         }
1590 skip:
1591                         w->state = FWS_U;
1592                 case FWS_U:
1593                         if (fn == w->root)
1594                                 return 0;
1595                         pn = fn->parent;
1596                         w->node = pn;
1597 #ifdef CONFIG_IPV6_SUBTREES
1598                         if (FIB6_SUBTREE(pn) == fn) {
1599                                 WARN_ON(!(fn->fn_flags & RTN_ROOT));
1600                                 w->state = FWS_L;
1601                                 continue;
1602                         }
1603 #endif
1604                         if (pn->left == fn) {
1605                                 w->state = FWS_R;
1606                                 continue;
1607                         }
1608                         if (pn->right == fn) {
1609                                 w->state = FWS_C;
1610                                 w->leaf = w->node->leaf;
1611                                 continue;
1612                         }
1613 #if RT6_DEBUG >= 2
1614                         WARN_ON(1);
1615 #endif
1616                 }
1617         }
1618 }
1619
1620 static int fib6_walk(struct net *net, struct fib6_walker *w)
1621 {
1622         int res;
1623
1624         w->state = FWS_INIT;
1625         w->node = w->root;
1626
1627         fib6_walker_link(net, w);
1628         res = fib6_walk_continue(w);
1629         if (res <= 0)
1630                 fib6_walker_unlink(net, w);
1631         return res;
1632 }
1633
1634 static int fib6_clean_node(struct fib6_walker *w)
1635 {
1636         int res;
1637         struct rt6_info *rt;
1638         struct fib6_cleaner *c = container_of(w, struct fib6_cleaner, w);
1639         struct nl_info info = {
1640                 .nl_net = c->net,
1641         };
1642
1643         if (c->sernum != FIB6_NO_SERNUM_CHANGE &&
1644             w->node->fn_sernum != c->sernum)
1645                 w->node->fn_sernum = c->sernum;
1646
1647         if (!c->func) {
1648                 WARN_ON_ONCE(c->sernum == FIB6_NO_SERNUM_CHANGE);
1649                 w->leaf = NULL;
1650                 return 0;
1651         }
1652
1653         for (rt = w->leaf; rt; rt = rt->dst.rt6_next) {
1654                 res = c->func(rt, c->arg);
1655                 if (res < 0) {
1656                         w->leaf = rt;
1657                         res = fib6_del(rt, &info);
1658                         if (res) {
1659 #if RT6_DEBUG >= 2
1660                                 pr_debug("%s: del failed: rt=%p@%p err=%d\n",
1661                                          __func__, rt, rt->rt6i_node, res);
1662 #endif
1663                                 continue;
1664                         }
1665                         return 0;
1666                 }
1667                 WARN_ON(res != 0);
1668         }
1669         w->leaf = rt;
1670         return 0;
1671 }
1672
1673 /*
1674  *      Convenient frontend to tree walker.
1675  *
1676  *      func is called on each route.
1677  *              It may return -1 -> delete this route.
1678  *                            0  -> continue walking
1679  *
1680  *      prune==1 -> only immediate children of node (certainly,
1681  *      ignoring pure split nodes) will be scanned.
1682  */
1683
1684 static void fib6_clean_tree(struct net *net, struct fib6_node *root,
1685                             int (*func)(struct rt6_info *, void *arg),
1686                             bool prune, int sernum, void *arg)
1687 {
1688         struct fib6_cleaner c;
1689
1690         c.w.root = root;
1691         c.w.func = fib6_clean_node;
1692         c.w.prune = prune;
1693         c.w.count = 0;
1694         c.w.skip = 0;
1695         c.func = func;
1696         c.sernum = sernum;
1697         c.arg = arg;
1698         c.net = net;
1699
1700         fib6_walk(net, &c.w);
1701 }
1702
1703 static void __fib6_clean_all(struct net *net,
1704                              int (*func)(struct rt6_info *, void *),
1705                              int sernum, void *arg)
1706 {
1707         struct fib6_table *table;
1708         struct hlist_head *head;
1709         unsigned int h;
1710
1711         rcu_read_lock();
1712         for (h = 0; h < FIB6_TABLE_HASHSZ; h++) {
1713                 head = &net->ipv6.fib_table_hash[h];
1714                 hlist_for_each_entry_rcu(table, head, tb6_hlist) {
1715                         write_lock_bh(&table->tb6_lock);
1716                         fib6_clean_tree(net, &table->tb6_root,
1717                                         func, false, sernum, arg);
1718                         write_unlock_bh(&table->tb6_lock);
1719                 }
1720         }
1721         rcu_read_unlock();
1722 }
1723
1724 void fib6_clean_all(struct net *net, int (*func)(struct rt6_info *, void *),
1725                     void *arg)
1726 {
1727         __fib6_clean_all(net, func, FIB6_NO_SERNUM_CHANGE, arg);
1728 }
1729
1730 static int fib6_prune_clone(struct rt6_info *rt, void *arg)
1731 {
1732         if (rt->rt6i_flags & RTF_CACHE) {
1733                 RT6_TRACE("pruning clone %p\n", rt);
1734                 return -1;
1735         }
1736
1737         return 0;
1738 }
1739
1740 static void fib6_prune_clones(struct net *net, struct fib6_node *fn)
1741 {
1742         fib6_clean_tree(net, fn, fib6_prune_clone, true,
1743                         FIB6_NO_SERNUM_CHANGE, NULL);
1744 }
1745
1746 static void fib6_flush_trees(struct net *net)
1747 {
1748         int new_sernum = fib6_new_sernum(net);
1749
1750         __fib6_clean_all(net, NULL, new_sernum, NULL);
1751 }
1752
1753 /*
1754  *      Garbage collection
1755  */
1756
1757 struct fib6_gc_args
1758 {
1759         int                     timeout;
1760         int                     more;
1761 };
1762
1763 static int fib6_age(struct rt6_info *rt, void *arg)
1764 {
1765         struct fib6_gc_args *gc_args = arg;
1766         unsigned long now = jiffies;
1767
1768         /*
1769          *      check addrconf expiration here.
1770          *      Routes are expired even if they are in use.
1771          *
1772          *      Also age clones. Note, that clones are aged out
1773          *      only if they are not in use now.
1774          */
1775
1776         if (rt->rt6i_flags & RTF_EXPIRES && rt->dst.expires) {
1777                 if (time_after(now, rt->dst.expires)) {
1778                         RT6_TRACE("expiring %p\n", rt);
1779                         return -1;
1780                 }
1781                 gc_args->more++;
1782         } else if (rt->rt6i_flags & RTF_CACHE) {
1783                 if (atomic_read(&rt->dst.__refcnt) == 1 &&
1784                     time_after_eq(now, rt->dst.lastuse + gc_args->timeout)) {
1785                         RT6_TRACE("aging clone %p\n", rt);
1786                         return -1;
1787                 } else if (rt->rt6i_flags & RTF_GATEWAY) {
1788                         struct neighbour *neigh;
1789                         __u8 neigh_flags = 0;
1790
1791                         neigh = dst_neigh_lookup(&rt->dst, &rt->rt6i_gateway);
1792                         if (neigh) {
1793                                 neigh_flags = neigh->flags;
1794                                 neigh_release(neigh);
1795                         }
1796                         if (!(neigh_flags & NTF_ROUTER)) {
1797                                 RT6_TRACE("purging route %p via non-router but gateway\n",
1798                                           rt);
1799                                 return -1;
1800                         }
1801                 }
1802                 gc_args->more++;
1803         }
1804
1805         return 0;
1806 }
1807
1808 void fib6_run_gc(unsigned long expires, struct net *net, bool force)
1809 {
1810         struct fib6_gc_args gc_args;
1811         unsigned long now;
1812
1813         if (force) {
1814                 spin_lock_bh(&net->ipv6.fib6_gc_lock);
1815         } else if (!spin_trylock_bh(&net->ipv6.fib6_gc_lock)) {
1816                 mod_timer(&net->ipv6.ip6_fib_timer, jiffies + HZ);
1817                 return;
1818         }
1819         gc_args.timeout = expires ? (int)expires :
1820                           net->ipv6.sysctl.ip6_rt_gc_interval;
1821         gc_args.more = 0;
1822
1823         fib6_clean_all(net, fib6_age, &gc_args);
1824         now = jiffies;
1825         net->ipv6.ip6_rt_last_gc = now;
1826
1827         if (gc_args.more)
1828                 mod_timer(&net->ipv6.ip6_fib_timer,
1829                           round_jiffies(now
1830                                         + net->ipv6.sysctl.ip6_rt_gc_interval));
1831         else
1832                 del_timer(&net->ipv6.ip6_fib_timer);
1833         spin_unlock_bh(&net->ipv6.fib6_gc_lock);
1834 }
1835
1836 static void fib6_gc_timer_cb(unsigned long arg)
1837 {
1838         fib6_run_gc(0, (struct net *)arg, true);
1839 }
1840
1841 static int __net_init fib6_net_init(struct net *net)
1842 {
1843         size_t size = sizeof(struct hlist_head) * FIB6_TABLE_HASHSZ;
1844
1845         spin_lock_init(&net->ipv6.fib6_gc_lock);
1846         rwlock_init(&net->ipv6.fib6_walker_lock);
1847         INIT_LIST_HEAD(&net->ipv6.fib6_walkers);
1848         setup_timer(&net->ipv6.ip6_fib_timer, fib6_gc_timer_cb, (unsigned long)net);
1849
1850         net->ipv6.rt6_stats = kzalloc(sizeof(*net->ipv6.rt6_stats), GFP_KERNEL);
1851         if (!net->ipv6.rt6_stats)
1852                 goto out_timer;
1853
1854         /* Avoid false sharing : Use at least a full cache line */
1855         size = max_t(size_t, size, L1_CACHE_BYTES);
1856
1857         net->ipv6.fib_table_hash = kzalloc(size, GFP_KERNEL);
1858         if (!net->ipv6.fib_table_hash)
1859                 goto out_rt6_stats;
1860
1861         net->ipv6.fib6_main_tbl = kzalloc(sizeof(*net->ipv6.fib6_main_tbl),
1862                                           GFP_KERNEL);
1863         if (!net->ipv6.fib6_main_tbl)
1864                 goto out_fib_table_hash;
1865
1866         net->ipv6.fib6_main_tbl->tb6_id = RT6_TABLE_MAIN;
1867         net->ipv6.fib6_main_tbl->tb6_root.leaf = net->ipv6.ip6_null_entry;
1868         net->ipv6.fib6_main_tbl->tb6_root.fn_flags =
1869                 RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
1870         inet_peer_base_init(&net->ipv6.fib6_main_tbl->tb6_peers);
1871
1872 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
1873         net->ipv6.fib6_local_tbl = kzalloc(sizeof(*net->ipv6.fib6_local_tbl),
1874                                            GFP_KERNEL);
1875         if (!net->ipv6.fib6_local_tbl)
1876                 goto out_fib6_main_tbl;
1877         net->ipv6.fib6_local_tbl->tb6_id = RT6_TABLE_LOCAL;
1878         net->ipv6.fib6_local_tbl->tb6_root.leaf = net->ipv6.ip6_null_entry;
1879         net->ipv6.fib6_local_tbl->tb6_root.fn_flags =
1880                 RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
1881         inet_peer_base_init(&net->ipv6.fib6_local_tbl->tb6_peers);
1882 #endif
1883         fib6_tables_init(net);
1884
1885         return 0;
1886
1887 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
1888 out_fib6_main_tbl:
1889         kfree(net->ipv6.fib6_main_tbl);
1890 #endif
1891 out_fib_table_hash:
1892         kfree(net->ipv6.fib_table_hash);
1893 out_rt6_stats:
1894         kfree(net->ipv6.rt6_stats);
1895 out_timer:
1896         return -ENOMEM;
1897 }
1898
1899 static void fib6_net_exit(struct net *net)
1900 {
1901         rt6_ifdown(net, NULL);
1902         del_timer_sync(&net->ipv6.ip6_fib_timer);
1903
1904 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
1905         inetpeer_invalidate_tree(&net->ipv6.fib6_local_tbl->tb6_peers);
1906         kfree(net->ipv6.fib6_local_tbl);
1907 #endif
1908         inetpeer_invalidate_tree(&net->ipv6.fib6_main_tbl->tb6_peers);
1909         kfree(net->ipv6.fib6_main_tbl);
1910         kfree(net->ipv6.fib_table_hash);
1911         kfree(net->ipv6.rt6_stats);
1912 }
1913
1914 static struct pernet_operations fib6_net_ops = {
1915         .init = fib6_net_init,
1916         .exit = fib6_net_exit,
1917 };
1918
1919 int __init fib6_init(void)
1920 {
1921         int ret = -ENOMEM;
1922
1923         fib6_node_kmem = kmem_cache_create("fib6_nodes",
1924                                            sizeof(struct fib6_node),
1925                                            0, SLAB_HWCACHE_ALIGN,
1926                                            NULL);
1927         if (!fib6_node_kmem)
1928                 goto out;
1929
1930         ret = register_pernet_subsys(&fib6_net_ops);
1931         if (ret)
1932                 goto out_kmem_cache_create;
1933
1934         ret = __rtnl_register(PF_INET6, RTM_GETROUTE, NULL, inet6_dump_fib,
1935                               NULL);
1936         if (ret)
1937                 goto out_unregister_subsys;
1938
1939         __fib6_flush_trees = fib6_flush_trees;
1940 out:
1941         return ret;
1942
1943 out_unregister_subsys:
1944         unregister_pernet_subsys(&fib6_net_ops);
1945 out_kmem_cache_create:
1946         kmem_cache_destroy(fib6_node_kmem);
1947         goto out;
1948 }
1949
1950 void fib6_gc_cleanup(void)
1951 {
1952         unregister_pernet_subsys(&fib6_net_ops);
1953         kmem_cache_destroy(fib6_node_kmem);
1954 }
1955
1956 #ifdef CONFIG_PROC_FS
1957
1958 struct ipv6_route_iter {
1959         struct seq_net_private p;
1960         struct fib6_walker w;
1961         loff_t skip;
1962         struct fib6_table *tbl;
1963         int sernum;
1964 };
1965
1966 static int ipv6_route_seq_show(struct seq_file *seq, void *v)
1967 {
1968         struct rt6_info *rt = v;
1969         struct ipv6_route_iter *iter = seq->private;
1970
1971         seq_printf(seq, "%pi6 %02x ", &rt->rt6i_dst.addr, rt->rt6i_dst.plen);
1972
1973 #ifdef CONFIG_IPV6_SUBTREES
1974         seq_printf(seq, "%pi6 %02x ", &rt->rt6i_src.addr, rt->rt6i_src.plen);
1975 #else
1976         seq_puts(seq, "00000000000000000000000000000000 00 ");
1977 #endif
1978         if (rt->rt6i_flags & RTF_GATEWAY)
1979                 seq_printf(seq, "%pi6", &rt->rt6i_gateway);
1980         else
1981                 seq_puts(seq, "00000000000000000000000000000000");
1982
1983         seq_printf(seq, " %08x %08x %08x %08x %8s\n",
1984                    rt->rt6i_metric, atomic_read(&rt->dst.__refcnt),
1985                    rt->dst.__use, rt->rt6i_flags,
1986                    rt->dst.dev ? rt->dst.dev->name : "");
1987         iter->w.leaf = NULL;
1988         return 0;
1989 }
1990
1991 static int ipv6_route_yield(struct fib6_walker *w)
1992 {
1993         struct ipv6_route_iter *iter = w->args;
1994
1995         if (!iter->skip)
1996                 return 1;
1997
1998         do {
1999                 iter->w.leaf = iter->w.leaf->dst.rt6_next;
2000                 iter->skip--;
2001                 if (!iter->skip && iter->w.leaf)
2002                         return 1;
2003         } while (iter->w.leaf);
2004
2005         return 0;
2006 }
2007
2008 static void ipv6_route_seq_setup_walk(struct ipv6_route_iter *iter,
2009                                       struct net *net)
2010 {
2011         memset(&iter->w, 0, sizeof(iter->w));
2012         iter->w.func = ipv6_route_yield;
2013         iter->w.root = &iter->tbl->tb6_root;
2014         iter->w.state = FWS_INIT;
2015         iter->w.node = iter->w.root;
2016         iter->w.args = iter;
2017         iter->sernum = iter->w.root->fn_sernum;
2018         INIT_LIST_HEAD(&iter->w.lh);
2019         fib6_walker_link(net, &iter->w);
2020 }
2021
2022 static struct fib6_table *ipv6_route_seq_next_table(struct fib6_table *tbl,
2023                                                     struct net *net)
2024 {
2025         unsigned int h;
2026         struct hlist_node *node;
2027
2028         if (tbl) {
2029                 h = (tbl->tb6_id & (FIB6_TABLE_HASHSZ - 1)) + 1;
2030                 node = rcu_dereference_bh(hlist_next_rcu(&tbl->tb6_hlist));
2031         } else {
2032                 h = 0;
2033                 node = NULL;
2034         }
2035
2036         while (!node && h < FIB6_TABLE_HASHSZ) {
2037                 node = rcu_dereference_bh(
2038                         hlist_first_rcu(&net->ipv6.fib_table_hash[h++]));
2039         }
2040         return hlist_entry_safe(node, struct fib6_table, tb6_hlist);
2041 }
2042
2043 static void ipv6_route_check_sernum(struct ipv6_route_iter *iter)
2044 {
2045         if (iter->sernum != iter->w.root->fn_sernum) {
2046                 iter->sernum = iter->w.root->fn_sernum;
2047                 iter->w.state = FWS_INIT;
2048                 iter->w.node = iter->w.root;
2049                 WARN_ON(iter->w.skip);
2050                 iter->w.skip = iter->w.count;
2051         }
2052 }
2053
2054 static void *ipv6_route_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2055 {
2056         int r;
2057         struct rt6_info *n;
2058         struct net *net = seq_file_net(seq);
2059         struct ipv6_route_iter *iter = seq->private;
2060
2061         if (!v)
2062                 goto iter_table;
2063
2064         n = ((struct rt6_info *)v)->dst.rt6_next;
2065         if (n) {
2066                 ++*pos;
2067                 return n;
2068         }
2069
2070 iter_table:
2071         ipv6_route_check_sernum(iter);
2072         read_lock(&iter->tbl->tb6_lock);
2073         r = fib6_walk_continue(&iter->w);
2074         read_unlock(&iter->tbl->tb6_lock);
2075         if (r > 0) {
2076                 if (v)
2077                         ++*pos;
2078                 return iter->w.leaf;
2079         } else if (r < 0) {
2080                 fib6_walker_unlink(net, &iter->w);
2081                 return NULL;
2082         }
2083         fib6_walker_unlink(net, &iter->w);
2084
2085         iter->tbl = ipv6_route_seq_next_table(iter->tbl, net);
2086         if (!iter->tbl)
2087                 return NULL;
2088
2089         ipv6_route_seq_setup_walk(iter, net);
2090         goto iter_table;
2091 }
2092
2093 static void *ipv6_route_seq_start(struct seq_file *seq, loff_t *pos)
2094         __acquires(RCU_BH)
2095 {
2096         struct net *net = seq_file_net(seq);
2097         struct ipv6_route_iter *iter = seq->private;
2098
2099         rcu_read_lock_bh();
2100         iter->tbl = ipv6_route_seq_next_table(NULL, net);
2101         iter->skip = *pos;
2102
2103         if (iter->tbl) {
2104                 ipv6_route_seq_setup_walk(iter, net);
2105                 return ipv6_route_seq_next(seq, NULL, pos);
2106         } else {
2107                 return NULL;
2108         }
2109 }
2110
2111 static bool ipv6_route_iter_active(struct ipv6_route_iter *iter)
2112 {
2113         struct fib6_walker *w = &iter->w;
2114         return w->node && !(w->state == FWS_U && w->node == w->root);
2115 }
2116
2117 static void ipv6_route_seq_stop(struct seq_file *seq, void *v)
2118         __releases(RCU_BH)
2119 {
2120         struct net *net = seq_file_net(seq);
2121         struct ipv6_route_iter *iter = seq->private;
2122
2123         if (ipv6_route_iter_active(iter))
2124                 fib6_walker_unlink(net, &iter->w);
2125
2126         rcu_read_unlock_bh();
2127 }
2128
2129 static const struct seq_operations ipv6_route_seq_ops = {
2130         .start  = ipv6_route_seq_start,
2131         .next   = ipv6_route_seq_next,
2132         .stop   = ipv6_route_seq_stop,
2133         .show   = ipv6_route_seq_show
2134 };
2135
2136 int ipv6_route_open(struct inode *inode, struct file *file)
2137 {
2138         return seq_open_net(inode, file, &ipv6_route_seq_ops,
2139                             sizeof(struct ipv6_route_iter));
2140 }
2141
2142 #endif /* CONFIG_PROC_FS */