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Linux/net/ipv6/ip6_fib.c

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  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 
 14 /*
 15  *      Changes:
 16  *      Yuji SEKIYA @USAGI:     Support default route on router node;
 17  *                              remove ip6_null_entry from the top of
 18  *                              routing table.
 19  *      Ville Nuorvala:         Fixed routing subtrees.
 20  */
 21 
 22 #define pr_fmt(fmt) "IPv6: " fmt
 23 
 24 #include <linux/errno.h>
 25 #include <linux/types.h>
 26 #include <linux/net.h>
 27 #include <linux/route.h>
 28 #include <linux/netdevice.h>
 29 #include <linux/in6.h>
 30 #include <linux/init.h>
 31 #include <linux/list.h>
 32 #include <linux/slab.h>
 33 
 34 #include <net/ipv6.h>
 35 #include <net/ndisc.h>
 36 #include <net/addrconf.h>
 37 
 38 #include <net/ip6_fib.h>
 39 #include <net/ip6_route.h>
 40 
 41 #define RT6_DEBUG 2
 42 
 43 #if RT6_DEBUG >= 3
 44 #define RT6_TRACE(x...) pr_debug(x)
 45 #else
 46 #define RT6_TRACE(x...) do { ; } while (0)
 47 #endif
 48 
 49 static struct kmem_cache * fib6_node_kmem __read_mostly;
 50 
 51 enum fib_walk_state_t
 52 {
 53 #ifdef CONFIG_IPV6_SUBTREES
 54         FWS_S,
 55 #endif
 56         FWS_L,
 57         FWS_R,
 58         FWS_C,
 59         FWS_U
 60 };
 61 
 62 struct fib6_cleaner_t
 63 {
 64         struct fib6_walker_t w;
 65         struct net *net;
 66         int (*func)(struct rt6_info *, void *arg);
 67         void *arg;
 68 };
 69 
 70 static DEFINE_RWLOCK(fib6_walker_lock);
 71 
 72 #ifdef CONFIG_IPV6_SUBTREES
 73 #define FWS_INIT FWS_S
 74 #else
 75 #define FWS_INIT FWS_L
 76 #endif
 77 
 78 static void fib6_prune_clones(struct net *net, struct fib6_node *fn,
 79                               struct rt6_info *rt);
 80 static struct rt6_info *fib6_find_prefix(struct net *net, struct fib6_node *fn);
 81 static struct fib6_node *fib6_repair_tree(struct net *net, struct fib6_node *fn);
 82 static int fib6_walk(struct fib6_walker_t *w);
 83 static int fib6_walk_continue(struct fib6_walker_t *w);
 84 
 85 /*
 86  *      A routing update causes an increase of the serial number on the
 87  *      affected subtree. This allows for cached routes to be asynchronously
 88  *      tested when modifications are made to the destination cache as a
 89  *      result of redirects, path MTU changes, etc.
 90  */
 91 
 92 static __u32 rt_sernum;
 93 
 94 static void fib6_gc_timer_cb(unsigned long arg);
 95 
 96 static LIST_HEAD(fib6_walkers);
 97 #define FOR_WALKERS(w) list_for_each_entry(w, &fib6_walkers, lh)
 98 
 99 static inline void fib6_walker_link(struct fib6_walker_t *w)
100 {
101         write_lock_bh(&fib6_walker_lock);
102         list_add(&w->lh, &fib6_walkers);
103         write_unlock_bh(&fib6_walker_lock);
104 }
105 
106 static inline void fib6_walker_unlink(struct fib6_walker_t *w)
107 {
108         write_lock_bh(&fib6_walker_lock);
109         list_del(&w->lh);
110         write_unlock_bh(&fib6_walker_lock);
111 }
112 static __inline__ u32 fib6_new_sernum(void)
113 {
114         u32 n = ++rt_sernum;
115         if ((__s32)n <= 0)
116                 rt_sernum = n = 1;
117         return n;
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 __inline__ __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 static __inline__ struct fib6_node * node_alloc(void)
151 {
152         struct fib6_node *fn;
153 
154         fn = kmem_cache_zalloc(fib6_node_kmem, GFP_ATOMIC);
155 
156         return fn;
157 }
158 
159 static __inline__ void node_free(struct fib6_node * fn)
160 {
161         kmem_cache_free(fib6_node_kmem, fn);
162 }
163 
164 static __inline__ void rt6_release(struct rt6_info *rt)
165 {
166         if (atomic_dec_and_test(&rt->rt6i_ref))
167                 dst_free(&rt->dst);
168 }
169 
170 static void fib6_link_table(struct net *net, struct fib6_table *tb)
171 {
172         unsigned int h;
173 
174         /*
175          * Initialize table lock at a single place to give lockdep a key,
176          * tables aren't visible prior to being linked to the list.
177          */
178         rwlock_init(&tb->tb6_lock);
179 
180         h = tb->tb6_id & (FIB6_TABLE_HASHSZ - 1);
181 
182         /*
183          * No protection necessary, this is the only list mutatation
184          * operation, tables never disappear once they exist.
185          */
186         hlist_add_head_rcu(&tb->tb6_hlist, &net->ipv6.fib_table_hash[h]);
187 }
188 
189 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
190 
191 static struct fib6_table *fib6_alloc_table(struct net *net, u32 id)
192 {
193         struct fib6_table *table;
194 
195         table = kzalloc(sizeof(*table), GFP_ATOMIC);
196         if (table) {
197                 table->tb6_id = id;
198                 table->tb6_root.leaf = net->ipv6.ip6_null_entry;
199                 table->tb6_root.fn_flags = RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
200                 inet_peer_base_init(&table->tb6_peers);
201         }
202 
203         return table;
204 }
205 
206 struct fib6_table *fib6_new_table(struct net *net, u32 id)
207 {
208         struct fib6_table *tb;
209 
210         if (id == 0)
211                 id = RT6_TABLE_MAIN;
212         tb = fib6_get_table(net, id);
213         if (tb)
214                 return tb;
215 
216         tb = fib6_alloc_table(net, id);
217         if (tb)
218                 fib6_link_table(net, tb);
219 
220         return tb;
221 }
222 
223 struct fib6_table *fib6_get_table(struct net *net, u32 id)
224 {
225         struct fib6_table *tb;
226         struct hlist_head *head;
227         unsigned int h;
228 
229         if (id == 0)
230                 id = RT6_TABLE_MAIN;
231         h = id & (FIB6_TABLE_HASHSZ - 1);
232         rcu_read_lock();
233         head = &net->ipv6.fib_table_hash[h];
234         hlist_for_each_entry_rcu(tb, head, tb6_hlist) {
235                 if (tb->tb6_id == id) {
236                         rcu_read_unlock();
237                         return tb;
238                 }
239         }
240         rcu_read_unlock();
241 
242         return NULL;
243 }
244 
245 static void __net_init fib6_tables_init(struct net *net)
246 {
247         fib6_link_table(net, net->ipv6.fib6_main_tbl);
248         fib6_link_table(net, net->ipv6.fib6_local_tbl);
249 }
250 #else
251 
252 struct fib6_table *fib6_new_table(struct net *net, u32 id)
253 {
254         return fib6_get_table(net, id);
255 }
256 
257 struct fib6_table *fib6_get_table(struct net *net, u32 id)
258 {
259           return net->ipv6.fib6_main_tbl;
260 }
261 
262 struct dst_entry *fib6_rule_lookup(struct net *net, struct flowi6 *fl6,
263                                    int flags, pol_lookup_t lookup)
264 {
265         return (struct dst_entry *) lookup(net, net->ipv6.fib6_main_tbl, fl6, flags);
266 }
267 
268 static void __net_init fib6_tables_init(struct net *net)
269 {
270         fib6_link_table(net, net->ipv6.fib6_main_tbl);
271 }
272 
273 #endif
274 
275 static int fib6_dump_node(struct fib6_walker_t *w)
276 {
277         int res;
278         struct rt6_info *rt;
279 
280         for (rt = w->leaf; rt; rt = rt->dst.rt6_next) {
281                 res = rt6_dump_route(rt, w->args);
282                 if (res < 0) {
283                         /* Frame is full, suspend walking */
284                         w->leaf = rt;
285                         return 1;
286                 }
287                 WARN_ON(res == 0);
288         }
289         w->leaf = NULL;
290         return 0;
291 }
292 
293 static void fib6_dump_end(struct netlink_callback *cb)
294 {
295         struct fib6_walker_t *w = (void*)cb->args[2];
296 
297         if (w) {
298                 if (cb->args[4]) {
299                         cb->args[4] = 0;
300                         fib6_walker_unlink(w);
301                 }
302                 cb->args[2] = 0;
303                 kfree(w);
304         }
305         cb->done = (void*)cb->args[3];
306         cb->args[1] = 3;
307 }
308 
309 static int fib6_dump_done(struct netlink_callback *cb)
310 {
311         fib6_dump_end(cb);
312         return cb->done ? cb->done(cb) : 0;
313 }
314 
315 static int fib6_dump_table(struct fib6_table *table, struct sk_buff *skb,
316                            struct netlink_callback *cb)
317 {
318         struct fib6_walker_t *w;
319         int res;
320 
321         w = (void *)cb->args[2];
322         w->root = &table->tb6_root;
323 
324         if (cb->args[4] == 0) {
325                 w->count = 0;
326                 w->skip = 0;
327 
328                 read_lock_bh(&table->tb6_lock);
329                 res = fib6_walk(w);
330                 read_unlock_bh(&table->tb6_lock);
331                 if (res > 0) {
332                         cb->args[4] = 1;
333                         cb->args[5] = w->root->fn_sernum;
334                 }
335         } else {
336                 if (cb->args[5] != w->root->fn_sernum) {
337                         /* Begin at the root if the tree changed */
338                         cb->args[5] = w->root->fn_sernum;
339                         w->state = FWS_INIT;
340                         w->node = w->root;
341                         w->skip = w->count;
342                 } else
343                         w->skip = 0;
344 
345                 read_lock_bh(&table->tb6_lock);
346                 res = fib6_walk_continue(w);
347                 read_unlock_bh(&table->tb6_lock);
348                 if (res <= 0) {
349                         fib6_walker_unlink(w);
350                         cb->args[4] = 0;
351                 }
352         }
353 
354         return res;
355 }
356 
357 static int inet6_dump_fib(struct sk_buff *skb, struct netlink_callback *cb)
358 {
359         struct net *net = sock_net(skb->sk);
360         unsigned int h, s_h;
361         unsigned int e = 0, s_e;
362         struct rt6_rtnl_dump_arg arg;
363         struct fib6_walker_t *w;
364         struct fib6_table *tb;
365         struct hlist_head *head;
366         int res = 0;
367 
368         s_h = cb->args[0];
369         s_e = cb->args[1];
370 
371         w = (void *)cb->args[2];
372         if (!w) {
373                 /* New dump:
374                  *
375                  * 1. hook callback destructor.
376                  */
377                 cb->args[3] = (long)cb->done;
378                 cb->done = fib6_dump_done;
379 
380                 /*
381                  * 2. allocate and initialize walker.
382                  */
383                 w = kzalloc(sizeof(*w), GFP_ATOMIC);
384                 if (!w)
385                         return -ENOMEM;
386                 w->func = fib6_dump_node;
387                 cb->args[2] = (long)w;
388         }
389 
390         arg.skb = skb;
391         arg.cb = cb;
392         arg.net = net;
393         w->args = &arg;
394 
395         rcu_read_lock();
396         for (h = s_h; h < FIB6_TABLE_HASHSZ; h++, s_e = 0) {
397                 e = 0;
398                 head = &net->ipv6.fib_table_hash[h];
399                 hlist_for_each_entry_rcu(tb, head, tb6_hlist) {
400                         if (e < s_e)
401                                 goto next;
402                         res = fib6_dump_table(tb, skb, cb);
403                         if (res != 0)
404                                 goto out;
405 next:
406                         e++;
407                 }
408         }
409 out:
410         rcu_read_unlock();
411         cb->args[1] = e;
412         cb->args[0] = h;
413 
414         res = res < 0 ? res : skb->len;
415         if (res <= 0)
416                 fib6_dump_end(cb);
417         return res;
418 }
419 
420 /*
421  *      Routing Table
422  *
423  *      return the appropriate node for a routing tree "add" operation
424  *      by either creating and inserting or by returning an existing
425  *      node.
426  */
427 
428 static struct fib6_node *fib6_add_1(struct fib6_node *root,
429                                      struct in6_addr *addr, int plen,
430                                      int offset, int allow_create,
431                                      int replace_required)
432 {
433         struct fib6_node *fn, *in, *ln;
434         struct fib6_node *pn = NULL;
435         struct rt6key *key;
436         int     bit;
437         __be32  dir = 0;
438         __u32   sernum = fib6_new_sernum();
439 
440         RT6_TRACE("fib6_add_1\n");
441 
442         /* insert node in tree */
443 
444         fn = root;
445 
446         do {
447                 key = (struct rt6key *)((u8 *)fn->leaf + offset);
448 
449                 /*
450                  *      Prefix match
451                  */
452                 if (plen < fn->fn_bit ||
453                     !ipv6_prefix_equal(&key->addr, addr, fn->fn_bit)) {
454                         if (!allow_create) {
455                                 if (replace_required) {
456                                         pr_warn("Can't replace route, no match found\n");
457                                         return ERR_PTR(-ENOENT);
458                                 }
459                                 pr_warn("NLM_F_CREATE should be set when creating new route\n");
460                         }
461                         goto insert_above;
462                 }
463 
464                 /*
465                  *      Exact match ?
466                  */
467 
468                 if (plen == fn->fn_bit) {
469                         /* clean up an intermediate node */
470                         if (!(fn->fn_flags & RTN_RTINFO)) {
471                                 rt6_release(fn->leaf);
472                                 fn->leaf = NULL;
473                         }
474 
475                         fn->fn_sernum = sernum;
476 
477                         return fn;
478                 }
479 
480                 /*
481                  *      We have more bits to go
482                  */
483 
484                 /* Try to walk down on tree. */
485                 fn->fn_sernum = sernum;
486                 dir = addr_bit_set(addr, fn->fn_bit);
487                 pn = fn;
488                 fn = dir ? fn->right: fn->left;
489         } while (fn);
490 
491         if (!allow_create) {
492                 /* We should not create new node because
493                  * NLM_F_REPLACE was specified without NLM_F_CREATE
494                  * I assume it is safe to require NLM_F_CREATE when
495                  * REPLACE flag is used! Later we may want to remove the
496                  * check for replace_required, because according
497                  * to netlink specification, NLM_F_CREATE
498                  * MUST be specified if new route is created.
499                  * That would keep IPv6 consistent with IPv4
500                  */
501                 if (replace_required) {
502                         pr_warn("Can't replace route, no match found\n");
503                         return ERR_PTR(-ENOENT);
504                 }
505                 pr_warn("NLM_F_CREATE should be set when creating new route\n");
506         }
507         /*
508          *      We walked to the bottom of tree.
509          *      Create new leaf node without children.
510          */
511 
512         ln = node_alloc();
513 
514         if (!ln)
515                 return ERR_PTR(-ENOMEM);
516         ln->fn_bit = plen;
517 
518         ln->parent = pn;
519         ln->fn_sernum = sernum;
520 
521         if (dir)
522                 pn->right = ln;
523         else
524                 pn->left  = ln;
525 
526         return ln;
527 
528 
529 insert_above:
530         /*
531          * split since we don't have a common prefix anymore or
532          * we have a less significant route.
533          * we've to insert an intermediate node on the list
534          * this new node will point to the one we need to create
535          * and the current
536          */
537 
538         pn = fn->parent;
539 
540         /* find 1st bit in difference between the 2 addrs.
541 
542            See comment in __ipv6_addr_diff: bit may be an invalid value,
543            but if it is >= plen, the value is ignored in any case.
544          */
545 
546         bit = __ipv6_addr_diff(addr, &key->addr, sizeof(*addr));
547 
548         /*
549          *              (intermediate)[in]
550          *                /        \
551          *      (new leaf node)[ln] (old node)[fn]
552          */
553         if (plen > bit) {
554                 in = node_alloc();
555                 ln = node_alloc();
556 
557                 if (!in || !ln) {
558                         if (in)
559                                 node_free(in);
560                         if (ln)
561                                 node_free(ln);
562                         return ERR_PTR(-ENOMEM);
563                 }
564 
565                 /*
566                  * new intermediate node.
567                  * RTN_RTINFO will
568                  * be off since that an address that chooses one of
569                  * the branches would not match less specific routes
570                  * in the other branch
571                  */
572 
573                 in->fn_bit = bit;
574 
575                 in->parent = pn;
576                 in->leaf = fn->leaf;
577                 atomic_inc(&in->leaf->rt6i_ref);
578 
579                 in->fn_sernum = sernum;
580 
581                 /* update parent pointer */
582                 if (dir)
583                         pn->right = in;
584                 else
585                         pn->left  = in;
586 
587                 ln->fn_bit = plen;
588 
589                 ln->parent = in;
590                 fn->parent = in;
591 
592                 ln->fn_sernum = sernum;
593 
594                 if (addr_bit_set(addr, bit)) {
595                         in->right = ln;
596                         in->left  = fn;
597                 } else {
598                         in->left  = ln;
599                         in->right = fn;
600                 }
601         } else { /* plen <= bit */
602 
603                 /*
604                  *              (new leaf node)[ln]
605                  *                /        \
606                  *           (old node)[fn] NULL
607                  */
608 
609                 ln = node_alloc();
610 
611                 if (!ln)
612                         return ERR_PTR(-ENOMEM);
613 
614                 ln->fn_bit = plen;
615 
616                 ln->parent = pn;
617 
618                 ln->fn_sernum = sernum;
619 
620                 if (dir)
621                         pn->right = ln;
622                 else
623                         pn->left  = ln;
624 
625                 if (addr_bit_set(&key->addr, plen))
626                         ln->right = fn;
627                 else
628                         ln->left  = fn;
629 
630                 fn->parent = ln;
631         }
632         return ln;
633 }
634 
635 static inline bool rt6_qualify_for_ecmp(struct rt6_info *rt)
636 {
637         return (rt->rt6i_flags & (RTF_GATEWAY|RTF_ADDRCONF|RTF_DYNAMIC)) ==
638                RTF_GATEWAY;
639 }
640 
641 static void fib6_purge_rt(struct rt6_info *rt, struct fib6_node *fn,
642                           struct net *net)
643 {
644         if (atomic_read(&rt->rt6i_ref) != 1) {
645                 /* This route is used as dummy address holder in some split
646                  * nodes. It is not leaked, but it still holds other resources,
647                  * which must be released in time. So, scan ascendant nodes
648                  * and replace dummy references to this route with references
649                  * to still alive ones.
650                  */
651                 while (fn) {
652                         if (!(fn->fn_flags & RTN_RTINFO) && fn->leaf == rt) {
653                                 fn->leaf = fib6_find_prefix(net, fn);
654                                 atomic_inc(&fn->leaf->rt6i_ref);
655                                 rt6_release(rt);
656                         }
657                         fn = fn->parent;
658                 }
659                 /* No more references are possible at this point. */
660                 BUG_ON(atomic_read(&rt->rt6i_ref) != 1);
661         }
662 }
663 
664 /*
665  *      Insert routing information in a node.
666  */
667 
668 static int fib6_add_rt2node(struct fib6_node *fn, struct rt6_info *rt,
669                             struct nl_info *info)
670 {
671         struct rt6_info *iter = NULL;
672         struct rt6_info **ins;
673         int replace = (info->nlh &&
674                        (info->nlh->nlmsg_flags & NLM_F_REPLACE));
675         int add = (!info->nlh ||
676                    (info->nlh->nlmsg_flags & NLM_F_CREATE));
677         int found = 0;
678         bool rt_can_ecmp = rt6_qualify_for_ecmp(rt);
679 
680         ins = &fn->leaf;
681 
682         for (iter = fn->leaf; iter; iter = iter->dst.rt6_next) {
683                 /*
684                  *      Search for duplicates
685                  */
686 
687                 if (iter->rt6i_metric == rt->rt6i_metric) {
688                         /*
689                          *      Same priority level
690                          */
691                         if (info->nlh &&
692                             (info->nlh->nlmsg_flags & NLM_F_EXCL))
693                                 return -EEXIST;
694                         if (replace) {
695                                 found++;
696                                 break;
697                         }
698 
699                         if (iter->dst.dev == rt->dst.dev &&
700                             iter->rt6i_idev == rt->rt6i_idev &&
701                             ipv6_addr_equal(&iter->rt6i_gateway,
702                                             &rt->rt6i_gateway)) {
703                                 if (rt->rt6i_nsiblings)
704                                         rt->rt6i_nsiblings = 0;
705                                 if (!(iter->rt6i_flags & RTF_EXPIRES))
706                                         return -EEXIST;
707                                 if (!(rt->rt6i_flags & RTF_EXPIRES))
708                                         rt6_clean_expires(iter);
709                                 else
710                                         rt6_set_expires(iter, rt->dst.expires);
711                                 return -EEXIST;
712                         }
713                         /* If we have the same destination and the same metric,
714                          * but not the same gateway, then the route we try to
715                          * add is sibling to this route, increment our counter
716                          * of siblings, and later we will add our route to the
717                          * list.
718                          * Only static routes (which don't have flag
719                          * RTF_EXPIRES) are used for ECMPv6.
720                          *
721                          * To avoid long list, we only had siblings if the
722                          * route have a gateway.
723                          */
724                         if (rt_can_ecmp &&
725                             rt6_qualify_for_ecmp(iter))
726                                 rt->rt6i_nsiblings++;
727                 }
728 
729                 if (iter->rt6i_metric > rt->rt6i_metric)
730                         break;
731 
732                 ins = &iter->dst.rt6_next;
733         }
734 
735         /* Reset round-robin state, if necessary */
736         if (ins == &fn->leaf)
737                 fn->rr_ptr = NULL;
738 
739         /* Link this route to others same route. */
740         if (rt->rt6i_nsiblings) {
741                 unsigned int rt6i_nsiblings;
742                 struct rt6_info *sibling, *temp_sibling;
743 
744                 /* Find the first route that have the same metric */
745                 sibling = fn->leaf;
746                 while (sibling) {
747                         if (sibling->rt6i_metric == rt->rt6i_metric &&
748                             rt6_qualify_for_ecmp(sibling)) {
749                                 list_add_tail(&rt->rt6i_siblings,
750                                               &sibling->rt6i_siblings);
751                                 break;
752                         }
753                         sibling = sibling->dst.rt6_next;
754                 }
755                 /* For each sibling in the list, increment the counter of
756                  * siblings. BUG() if counters does not match, list of siblings
757                  * is broken!
758                  */
759                 rt6i_nsiblings = 0;
760                 list_for_each_entry_safe(sibling, temp_sibling,
761                                          &rt->rt6i_siblings, rt6i_siblings) {
762                         sibling->rt6i_nsiblings++;
763                         BUG_ON(sibling->rt6i_nsiblings != rt->rt6i_nsiblings);
764                         rt6i_nsiblings++;
765                 }
766                 BUG_ON(rt6i_nsiblings != rt->rt6i_nsiblings);
767         }
768 
769         /*
770          *      insert node
771          */
772         if (!replace) {
773                 if (!add)
774                         pr_warn("NLM_F_CREATE should be set when creating new route\n");
775 
776 add:
777                 rt->dst.rt6_next = iter;
778                 *ins = rt;
779                 rt->rt6i_node = fn;
780                 atomic_inc(&rt->rt6i_ref);
781                 inet6_rt_notify(RTM_NEWROUTE, rt, info);
782                 info->nl_net->ipv6.rt6_stats->fib_rt_entries++;
783 
784                 if (!(fn->fn_flags & RTN_RTINFO)) {
785                         info->nl_net->ipv6.rt6_stats->fib_route_nodes++;
786                         fn->fn_flags |= RTN_RTINFO;
787                 }
788 
789         } else {
790                 if (!found) {
791                         if (add)
792                                 goto add;
793                         pr_warn("NLM_F_REPLACE set, but no existing node found!\n");
794                         return -ENOENT;
795                 }
796                 *ins = rt;
797                 rt->rt6i_node = fn;
798                 rt->dst.rt6_next = iter->dst.rt6_next;
799                 atomic_inc(&rt->rt6i_ref);
800                 inet6_rt_notify(RTM_NEWROUTE, rt, info);
801                 if (!(fn->fn_flags & RTN_RTINFO)) {
802                         info->nl_net->ipv6.rt6_stats->fib_route_nodes++;
803                         fn->fn_flags |= RTN_RTINFO;
804                 }
805                 fib6_purge_rt(iter, fn, info->nl_net);
806                 rt6_release(iter);
807         }
808 
809         return 0;
810 }
811 
812 static __inline__ void fib6_start_gc(struct net *net, struct rt6_info *rt)
813 {
814         if (!timer_pending(&net->ipv6.ip6_fib_timer) &&
815             (rt->rt6i_flags & (RTF_EXPIRES | RTF_CACHE)))
816                 mod_timer(&net->ipv6.ip6_fib_timer,
817                           jiffies + net->ipv6.sysctl.ip6_rt_gc_interval);
818 }
819 
820 void fib6_force_start_gc(struct net *net)
821 {
822         if (!timer_pending(&net->ipv6.ip6_fib_timer))
823                 mod_timer(&net->ipv6.ip6_fib_timer,
824                           jiffies + net->ipv6.sysctl.ip6_rt_gc_interval);
825 }
826 
827 /*
828  *      Add routing information to the routing tree.
829  *      <destination addr>/<source addr>
830  *      with source addr info in sub-trees
831  */
832 
833 int fib6_add(struct fib6_node *root, struct rt6_info *rt, struct nl_info *info)
834 {
835         struct fib6_node *fn, *pn = NULL;
836         int err = -ENOMEM;
837         int allow_create = 1;
838         int replace_required = 0;
839 
840         if (info->nlh) {
841                 if (!(info->nlh->nlmsg_flags & NLM_F_CREATE))
842                         allow_create = 0;
843                 if (info->nlh->nlmsg_flags & NLM_F_REPLACE)
844                         replace_required = 1;
845         }
846         if (!allow_create && !replace_required)
847                 pr_warn("RTM_NEWROUTE with no NLM_F_CREATE or NLM_F_REPLACE\n");
848 
849         fn = fib6_add_1(root, &rt->rt6i_dst.addr, rt->rt6i_dst.plen,
850                         offsetof(struct rt6_info, rt6i_dst), allow_create,
851                         replace_required);
852         if (IS_ERR(fn)) {
853                 err = PTR_ERR(fn);
854                 fn = NULL;
855                 goto out;
856         }
857 
858         pn = fn;
859 
860 #ifdef CONFIG_IPV6_SUBTREES
861         if (rt->rt6i_src.plen) {
862                 struct fib6_node *sn;
863 
864                 if (!fn->subtree) {
865                         struct fib6_node *sfn;
866 
867                         /*
868                          * Create subtree.
869                          *
870                          *              fn[main tree]
871                          *              |
872                          *              sfn[subtree root]
873                          *                 \
874                          *                  sn[new leaf node]
875                          */
876 
877                         /* Create subtree root node */
878                         sfn = node_alloc();
879                         if (!sfn)
880                                 goto st_failure;
881 
882                         sfn->leaf = info->nl_net->ipv6.ip6_null_entry;
883                         atomic_inc(&info->nl_net->ipv6.ip6_null_entry->rt6i_ref);
884                         sfn->fn_flags = RTN_ROOT;
885                         sfn->fn_sernum = fib6_new_sernum();
886 
887                         /* Now add the first leaf node to new subtree */
888 
889                         sn = fib6_add_1(sfn, &rt->rt6i_src.addr,
890                                         rt->rt6i_src.plen,
891                                         offsetof(struct rt6_info, rt6i_src),
892                                         allow_create, replace_required);
893 
894                         if (IS_ERR(sn)) {
895                                 /* If it is failed, discard just allocated
896                                    root, and then (in st_failure) stale node
897                                    in main tree.
898                                  */
899                                 node_free(sfn);
900                                 err = PTR_ERR(sn);
901                                 goto st_failure;
902                         }
903 
904                         /* Now link new subtree to main tree */
905                         sfn->parent = fn;
906                         fn->subtree = sfn;
907                 } else {
908                         sn = fib6_add_1(fn->subtree, &rt->rt6i_src.addr,
909                                         rt->rt6i_src.plen,
910                                         offsetof(struct rt6_info, rt6i_src),
911                                         allow_create, replace_required);
912 
913                         if (IS_ERR(sn)) {
914                                 err = PTR_ERR(sn);
915                                 goto st_failure;
916                         }
917                 }
918 
919                 if (!fn->leaf) {
920                         fn->leaf = rt;
921                         atomic_inc(&rt->rt6i_ref);
922                 }
923                 fn = sn;
924         }
925 #endif
926 
927         err = fib6_add_rt2node(fn, rt, info);
928         if (!err) {
929                 fib6_start_gc(info->nl_net, rt);
930                 if (!(rt->rt6i_flags & RTF_CACHE))
931                         fib6_prune_clones(info->nl_net, pn, rt);
932         }
933 
934 out:
935         if (err) {
936 #ifdef CONFIG_IPV6_SUBTREES
937                 /*
938                  * If fib6_add_1 has cleared the old leaf pointer in the
939                  * super-tree leaf node we have to find a new one for it.
940                  */
941                 if (pn != fn && pn->leaf == rt) {
942                         pn->leaf = NULL;
943                         atomic_dec(&rt->rt6i_ref);
944                 }
945                 if (pn != fn && !pn->leaf && !(pn->fn_flags & RTN_RTINFO)) {
946                         pn->leaf = fib6_find_prefix(info->nl_net, pn);
947 #if RT6_DEBUG >= 2
948                         if (!pn->leaf) {
949                                 WARN_ON(pn->leaf == NULL);
950                                 pn->leaf = info->nl_net->ipv6.ip6_null_entry;
951                         }
952 #endif
953                         atomic_inc(&pn->leaf->rt6i_ref);
954                 }
955 #endif
956                 dst_free(&rt->dst);
957         }
958         return err;
959 
960 #ifdef CONFIG_IPV6_SUBTREES
961         /* Subtree creation failed, probably main tree node
962            is orphan. If it is, shoot it.
963          */
964 st_failure:
965         if (fn && !(fn->fn_flags & (RTN_RTINFO|RTN_ROOT)))
966                 fib6_repair_tree(info->nl_net, fn);
967         dst_free(&rt->dst);
968         return err;
969 #endif
970 }
971 
972 /*
973  *      Routing tree lookup
974  *
975  */
976 
977 struct lookup_args {
978         int                     offset;         /* key offset on rt6_info       */
979         const struct in6_addr   *addr;          /* search key                   */
980 };
981 
982 static struct fib6_node * fib6_lookup_1(struct fib6_node *root,
983                                         struct lookup_args *args)
984 {
985         struct fib6_node *fn;
986         __be32 dir;
987 
988         if (unlikely(args->offset == 0))
989                 return NULL;
990 
991         /*
992          *      Descend on a tree
993          */
994 
995         fn = root;
996 
997         for (;;) {
998                 struct fib6_node *next;
999 
1000                 dir = addr_bit_set(args->addr, fn->fn_bit);
1001 
1002                 next = dir ? fn->right : fn->left;
1003 
1004                 if (next) {
1005                         fn = next;
1006                         continue;
1007                 }
1008                 break;
1009         }
1010 
1011         while (fn) {
1012                 if (FIB6_SUBTREE(fn) || fn->fn_flags & RTN_RTINFO) {
1013                         struct rt6key *key;
1014 
1015                         key = (struct rt6key *) ((u8 *) fn->leaf +
1016                                                  args->offset);
1017 
1018                         if (ipv6_prefix_equal(&key->addr, args->addr, key->plen)) {
1019 #ifdef CONFIG_IPV6_SUBTREES
1020                                 if (fn->subtree) {
1021                                         struct fib6_node *sfn;
1022                                         sfn = fib6_lookup_1(fn->subtree,
1023                                                             args + 1);
1024                                         if (!sfn)
1025                                                 goto backtrack;
1026                                         fn = sfn;
1027                                 }
1028 #endif
1029                                 if (fn->fn_flags & RTN_RTINFO)
1030                                         return fn;
1031                         }
1032                 }
1033 #ifdef CONFIG_IPV6_SUBTREES
1034 backtrack:
1035 #endif
1036                 if (fn->fn_flags & RTN_ROOT)
1037                         break;
1038 
1039                 fn = fn->parent;
1040         }
1041 
1042         return NULL;
1043 }
1044 
1045 struct fib6_node * fib6_lookup(struct fib6_node *root, const struct in6_addr *daddr,
1046                                const struct in6_addr *saddr)
1047 {
1048         struct fib6_node *fn;
1049         struct lookup_args args[] = {
1050                 {
1051                         .offset = offsetof(struct rt6_info, rt6i_dst),
1052                         .addr = daddr,
1053                 },
1054 #ifdef CONFIG_IPV6_SUBTREES
1055                 {
1056                         .offset = offsetof(struct rt6_info, rt6i_src),
1057                         .addr = saddr,
1058                 },
1059 #endif
1060                 {
1061                         .offset = 0,    /* sentinel */
1062                 }
1063         };
1064 
1065         fn = fib6_lookup_1(root, daddr ? args : args + 1);
1066         if (!fn || fn->fn_flags & RTN_TL_ROOT)
1067                 fn = root;
1068 
1069         return fn;
1070 }
1071 
1072 /*
1073  *      Get node with specified destination prefix (and source prefix,
1074  *      if subtrees are used)
1075  */
1076 
1077 
1078 static struct fib6_node * fib6_locate_1(struct fib6_node *root,
1079                                         const struct in6_addr *addr,
1080                                         int plen, int offset)
1081 {
1082         struct fib6_node *fn;
1083 
1084         for (fn = root; fn ; ) {
1085                 struct rt6key *key = (struct rt6key *)((u8 *)fn->leaf + offset);
1086 
1087                 /*
1088                  *      Prefix match
1089                  */
1090                 if (plen < fn->fn_bit ||
1091                     !ipv6_prefix_equal(&key->addr, addr, fn->fn_bit))
1092                         return NULL;
1093 
1094                 if (plen == fn->fn_bit)
1095                         return fn;
1096 
1097                 /*
1098                  *      We have more bits to go
1099                  */
1100                 if (addr_bit_set(addr, fn->fn_bit))
1101                         fn = fn->right;
1102                 else
1103                         fn = fn->left;
1104         }
1105         return NULL;
1106 }
1107 
1108 struct fib6_node * fib6_locate(struct fib6_node *root,
1109                                const struct in6_addr *daddr, int dst_len,
1110                                const struct in6_addr *saddr, int src_len)
1111 {
1112         struct fib6_node *fn;
1113 
1114         fn = fib6_locate_1(root, daddr, dst_len,
1115                            offsetof(struct rt6_info, rt6i_dst));
1116 
1117 #ifdef CONFIG_IPV6_SUBTREES
1118         if (src_len) {
1119                 WARN_ON(saddr == NULL);
1120                 if (fn && fn->subtree)
1121                         fn = fib6_locate_1(fn->subtree, saddr, src_len,
1122                                            offsetof(struct rt6_info, rt6i_src));
1123         }
1124 #endif
1125 
1126         if (fn && fn->fn_flags & RTN_RTINFO)
1127                 return fn;
1128 
1129         return NULL;
1130 }
1131 
1132 
1133 /*
1134  *      Deletion
1135  *
1136  */
1137 
1138 static struct rt6_info *fib6_find_prefix(struct net *net, struct fib6_node *fn)
1139 {
1140         if (fn->fn_flags & RTN_ROOT)
1141                 return net->ipv6.ip6_null_entry;
1142 
1143         while (fn) {
1144                 if (fn->left)
1145                         return fn->left->leaf;
1146                 if (fn->right)
1147                         return fn->right->leaf;
1148 
1149                 fn = FIB6_SUBTREE(fn);
1150         }
1151         return NULL;
1152 }
1153 
1154 /*
1155  *      Called to trim the tree of intermediate nodes when possible. "fn"
1156  *      is the node we want to try and remove.
1157  */
1158 
1159 static struct fib6_node *fib6_repair_tree(struct net *net,
1160                                            struct fib6_node *fn)
1161 {
1162         int children;
1163         int nstate;
1164         struct fib6_node *child, *pn;
1165         struct fib6_walker_t *w;
1166         int iter = 0;
1167 
1168         for (;;) {
1169                 RT6_TRACE("fixing tree: plen=%d iter=%d\n", fn->fn_bit, iter);
1170                 iter++;
1171 
1172                 WARN_ON(fn->fn_flags & RTN_RTINFO);
1173                 WARN_ON(fn->fn_flags & RTN_TL_ROOT);
1174                 WARN_ON(fn->leaf != NULL);
1175 
1176                 children = 0;
1177                 child = NULL;
1178                 if (fn->right) child = fn->right, children |= 1;
1179                 if (fn->left) child = fn->left, children |= 2;
1180 
1181                 if (children == 3 || FIB6_SUBTREE(fn)
1182 #ifdef CONFIG_IPV6_SUBTREES
1183                     /* Subtree root (i.e. fn) may have one child */
1184                     || (children && fn->fn_flags & RTN_ROOT)
1185 #endif
1186                     ) {
1187                         fn->leaf = fib6_find_prefix(net, fn);
1188 #if RT6_DEBUG >= 2
1189                         if (!fn->leaf) {
1190                                 WARN_ON(!fn->leaf);
1191                                 fn->leaf = net->ipv6.ip6_null_entry;
1192                         }
1193 #endif
1194                         atomic_inc(&fn->leaf->rt6i_ref);
1195                         return fn->parent;
1196                 }
1197 
1198                 pn = fn->parent;
1199 #ifdef CONFIG_IPV6_SUBTREES
1200                 if (FIB6_SUBTREE(pn) == fn) {
1201                         WARN_ON(!(fn->fn_flags & RTN_ROOT));
1202                         FIB6_SUBTREE(pn) = NULL;
1203                         nstate = FWS_L;
1204                 } else {
1205                         WARN_ON(fn->fn_flags & RTN_ROOT);
1206 #endif
1207                         if (pn->right == fn) pn->right = child;
1208                         else if (pn->left == fn) pn->left = child;
1209 #if RT6_DEBUG >= 2
1210                         else
1211                                 WARN_ON(1);
1212 #endif
1213                         if (child)
1214                                 child->parent = pn;
1215                         nstate = FWS_R;
1216 #ifdef CONFIG_IPV6_SUBTREES
1217                 }
1218 #endif
1219 
1220                 read_lock(&fib6_walker_lock);
1221                 FOR_WALKERS(w) {
1222                         if (!child) {
1223                                 if (w->root == fn) {
1224                                         w->root = w->node = NULL;
1225                                         RT6_TRACE("W %p adjusted by delroot 1\n", w);
1226                                 } else if (w->node == fn) {
1227                                         RT6_TRACE("W %p adjusted by delnode 1, s=%d/%d\n", w, w->state, nstate);
1228                                         w->node = pn;
1229                                         w->state = nstate;
1230                                 }
1231                         } else {
1232                                 if (w->root == fn) {
1233                                         w->root = child;
1234                                         RT6_TRACE("W %p adjusted by delroot 2\n", w);
1235                                 }
1236                                 if (w->node == fn) {
1237                                         w->node = child;
1238                                         if (children&2) {
1239                                                 RT6_TRACE("W %p adjusted by delnode 2, s=%d\n", w, w->state);
1240                                                 w->state = w->state>=FWS_R ? FWS_U : FWS_INIT;
1241                                         } else {
1242                                                 RT6_TRACE("W %p adjusted by delnode 2, s=%d\n", w, w->state);
1243                                                 w->state = w->state>=FWS_C ? FWS_U : FWS_INIT;
1244                                         }
1245                                 }
1246                         }
1247                 }
1248                 read_unlock(&fib6_walker_lock);
1249 
1250                 node_free(fn);
1251                 if (pn->fn_flags & RTN_RTINFO || FIB6_SUBTREE(pn))
1252                         return pn;
1253 
1254                 rt6_release(pn->leaf);
1255                 pn->leaf = NULL;
1256                 fn = pn;
1257         }
1258 }
1259 
1260 static void fib6_del_route(struct fib6_node *fn, struct rt6_info **rtp,
1261                            struct nl_info *info)
1262 {
1263         struct fib6_walker_t *w;
1264         struct rt6_info *rt = *rtp;
1265         struct net *net = info->nl_net;
1266 
1267         RT6_TRACE("fib6_del_route\n");
1268 
1269         /* Unlink it */
1270         *rtp = rt->dst.rt6_next;
1271         rt->rt6i_node = NULL;
1272         net->ipv6.rt6_stats->fib_rt_entries--;
1273         net->ipv6.rt6_stats->fib_discarded_routes++;
1274 
1275         /* Reset round-robin state, if necessary */
1276         if (fn->rr_ptr == rt)
1277                 fn->rr_ptr = NULL;
1278 
1279         /* Remove this entry from other siblings */
1280         if (rt->rt6i_nsiblings) {
1281                 struct rt6_info *sibling, *next_sibling;
1282 
1283                 list_for_each_entry_safe(sibling, next_sibling,
1284                                          &rt->rt6i_siblings, rt6i_siblings)
1285                         sibling->rt6i_nsiblings--;
1286                 rt->rt6i_nsiblings = 0;
1287                 list_del_init(&rt->rt6i_siblings);
1288         }
1289 
1290         /* Adjust walkers */
1291         read_lock(&fib6_walker_lock);
1292         FOR_WALKERS(w) {
1293                 if (w->state == FWS_C && w->leaf == rt) {
1294                         RT6_TRACE("walker %p adjusted by delroute\n", w);
1295                         w->leaf = rt->dst.rt6_next;
1296                         if (!w->leaf)
1297                                 w->state = FWS_U;
1298                 }
1299         }
1300         read_unlock(&fib6_walker_lock);
1301 
1302         rt->dst.rt6_next = NULL;
1303 
1304         /* If it was last route, expunge its radix tree node */
1305         if (!fn->leaf) {
1306                 fn->fn_flags &= ~RTN_RTINFO;
1307                 net->ipv6.rt6_stats->fib_route_nodes--;
1308                 fn = fib6_repair_tree(net, fn);
1309         }
1310 
1311         fib6_purge_rt(rt, fn, net);
1312 
1313         inet6_rt_notify(RTM_DELROUTE, rt, info);
1314         rt6_release(rt);
1315 }
1316 
1317 int fib6_del(struct rt6_info *rt, struct nl_info *info)
1318 {
1319         struct net *net = info->nl_net;
1320         struct fib6_node *fn = rt->rt6i_node;
1321         struct rt6_info **rtp;
1322 
1323 #if RT6_DEBUG >= 2
1324         if (rt->dst.obsolete>0) {
1325                 WARN_ON(fn != NULL);
1326                 return -ENOENT;
1327         }
1328 #endif
1329         if (!fn || rt == net->ipv6.ip6_null_entry)
1330                 return -ENOENT;
1331 
1332         WARN_ON(!(fn->fn_flags & RTN_RTINFO));
1333 
1334         if (!(rt->rt6i_flags & RTF_CACHE)) {
1335                 struct fib6_node *pn = fn;
1336 #ifdef CONFIG_IPV6_SUBTREES
1337                 /* clones of this route might be in another subtree */
1338                 if (rt->rt6i_src.plen) {
1339                         while (!(pn->fn_flags & RTN_ROOT))
1340                                 pn = pn->parent;
1341                         pn = pn->parent;
1342                 }
1343 #endif
1344                 fib6_prune_clones(info->nl_net, pn, rt);
1345         }
1346 
1347         /*
1348          *      Walk the leaf entries looking for ourself
1349          */
1350 
1351         for (rtp = &fn->leaf; *rtp; rtp = &(*rtp)->dst.rt6_next) {
1352                 if (*rtp == rt) {
1353                         fib6_del_route(fn, rtp, info);
1354                         return 0;
1355                 }
1356         }
1357         return -ENOENT;
1358 }
1359 
1360 /*
1361  *      Tree traversal function.
1362  *
1363  *      Certainly, it is not interrupt safe.
1364  *      However, it is internally reenterable wrt itself and fib6_add/fib6_del.
1365  *      It means, that we can modify tree during walking
1366  *      and use this function for garbage collection, clone pruning,
1367  *      cleaning tree when a device goes down etc. etc.
1368  *
1369  *      It guarantees that every node will be traversed,
1370  *      and that it will be traversed only once.
1371  *
1372  *      Callback function w->func may return:
1373  *      0 -> continue walking.
1374  *      positive value -> walking is suspended (used by tree dumps,
1375  *      and probably by gc, if it will be split to several slices)
1376  *      negative value -> terminate walking.
1377  *
1378  *      The function itself returns:
1379  *      0   -> walk is complete.
1380  *      >0  -> walk is incomplete (i.e. suspended)
1381  *      <0  -> walk is terminated by an error.
1382  */
1383 
1384 static int fib6_walk_continue(struct fib6_walker_t *w)
1385 {
1386         struct fib6_node *fn, *pn;
1387 
1388         for (;;) {
1389                 fn = w->node;
1390                 if (!fn)
1391                         return 0;
1392 
1393                 if (w->prune && fn != w->root &&
1394                     fn->fn_flags & RTN_RTINFO && w->state < FWS_C) {
1395                         w->state = FWS_C;
1396                         w->leaf = fn->leaf;
1397                 }
1398                 switch (w->state) {
1399 #ifdef CONFIG_IPV6_SUBTREES
1400                 case FWS_S:
1401                         if (FIB6_SUBTREE(fn)) {
1402                                 w->node = FIB6_SUBTREE(fn);
1403                                 continue;
1404                         }
1405                         w->state = FWS_L;
1406 #endif
1407                 case FWS_L:
1408                         if (fn->left) {
1409                                 w->node = fn->left;
1410                                 w->state = FWS_INIT;
1411                                 continue;
1412                         }
1413                         w->state = FWS_R;
1414                 case FWS_R:
1415                         if (fn->right) {
1416                                 w->node = fn->right;
1417                                 w->state = FWS_INIT;
1418                                 continue;
1419                         }
1420                         w->state = FWS_C;
1421                         w->leaf = fn->leaf;
1422                 case FWS_C:
1423                         if (w->leaf && fn->fn_flags & RTN_RTINFO) {
1424                                 int err;
1425 
1426                                 if (w->skip) {
1427                                         w->skip--;
1428                                         goto skip;
1429                                 }
1430 
1431                                 err = w->func(w);
1432                                 if (err)
1433                                         return err;
1434 
1435                                 w->count++;
1436                                 continue;
1437                         }
1438 skip:
1439                         w->state = FWS_U;
1440                 case FWS_U:
1441                         if (fn == w->root)
1442                                 return 0;
1443                         pn = fn->parent;
1444                         w->node = pn;
1445 #ifdef CONFIG_IPV6_SUBTREES
1446                         if (FIB6_SUBTREE(pn) == fn) {
1447                                 WARN_ON(!(fn->fn_flags & RTN_ROOT));
1448                                 w->state = FWS_L;
1449                                 continue;
1450                         }
1451 #endif
1452                         if (pn->left == fn) {
1453                                 w->state = FWS_R;
1454                                 continue;
1455                         }
1456                         if (pn->right == fn) {
1457                                 w->state = FWS_C;
1458                                 w->leaf = w->node->leaf;
1459                                 continue;
1460                         }
1461 #if RT6_DEBUG >= 2
1462                         WARN_ON(1);
1463 #endif
1464                 }
1465         }
1466 }
1467 
1468 static int fib6_walk(struct fib6_walker_t *w)
1469 {
1470         int res;
1471 
1472         w->state = FWS_INIT;
1473         w->node = w->root;
1474 
1475         fib6_walker_link(w);
1476         res = fib6_walk_continue(w);
1477         if (res <= 0)
1478                 fib6_walker_unlink(w);
1479         return res;
1480 }
1481 
1482 static int fib6_clean_node(struct fib6_walker_t *w)
1483 {
1484         int res;
1485         struct rt6_info *rt;
1486         struct fib6_cleaner_t *c = container_of(w, struct fib6_cleaner_t, w);
1487         struct nl_info info = {
1488                 .nl_net = c->net,
1489         };
1490 
1491         for (rt = w->leaf; rt; rt = rt->dst.rt6_next) {
1492                 res = c->func(rt, c->arg);
1493                 if (res < 0) {
1494                         w->leaf = rt;
1495                         res = fib6_del(rt, &info);
1496                         if (res) {
1497 #if RT6_DEBUG >= 2
1498                                 pr_debug("%s: del failed: rt=%p@%p err=%d\n",
1499                                          __func__, rt, rt->rt6i_node, res);
1500 #endif
1501                                 continue;
1502                         }
1503                         return 0;
1504                 }
1505                 WARN_ON(res != 0);
1506         }
1507         w->leaf = rt;
1508         return 0;
1509 }
1510 
1511 /*
1512  *      Convenient frontend to tree walker.
1513  *
1514  *      func is called on each route.
1515  *              It may return -1 -> delete this route.
1516  *                            0  -> continue walking
1517  *
1518  *      prune==1 -> only immediate children of node (certainly,
1519  *      ignoring pure split nodes) will be scanned.
1520  */
1521 
1522 static void fib6_clean_tree(struct net *net, struct fib6_node *root,
1523                             int (*func)(struct rt6_info *, void *arg),
1524                             int prune, void *arg)
1525 {
1526         struct fib6_cleaner_t c;
1527 
1528         c.w.root = root;
1529         c.w.func = fib6_clean_node;
1530         c.w.prune = prune;
1531         c.w.count = 0;
1532         c.w.skip = 0;
1533         c.func = func;
1534         c.arg = arg;
1535         c.net = net;
1536 
1537         fib6_walk(&c.w);
1538 }
1539 
1540 void fib6_clean_all_ro(struct net *net, int (*func)(struct rt6_info *, void *arg),
1541                     int prune, void *arg)
1542 {
1543         struct fib6_table *table;
1544         struct hlist_head *head;
1545         unsigned int h;
1546 
1547         rcu_read_lock();
1548         for (h = 0; h < FIB6_TABLE_HASHSZ; h++) {
1549                 head = &net->ipv6.fib_table_hash[h];
1550                 hlist_for_each_entry_rcu(table, head, tb6_hlist) {
1551                         read_lock_bh(&table->tb6_lock);
1552                         fib6_clean_tree(net, &table->tb6_root,
1553                                         func, prune, arg);
1554                         read_unlock_bh(&table->tb6_lock);
1555                 }
1556         }
1557         rcu_read_unlock();
1558 }
1559 void fib6_clean_all(struct net *net, int (*func)(struct rt6_info *, void *arg),
1560                     int prune, void *arg)
1561 {
1562         struct fib6_table *table;
1563         struct hlist_head *head;
1564         unsigned int h;
1565 
1566         rcu_read_lock();
1567         for (h = 0; h < FIB6_TABLE_HASHSZ; h++) {
1568                 head = &net->ipv6.fib_table_hash[h];
1569                 hlist_for_each_entry_rcu(table, head, tb6_hlist) {
1570                         write_lock_bh(&table->tb6_lock);
1571                         fib6_clean_tree(net, &table->tb6_root,
1572                                         func, prune, arg);
1573                         write_unlock_bh(&table->tb6_lock);
1574                 }
1575         }
1576         rcu_read_unlock();
1577 }
1578 
1579 static int fib6_prune_clone(struct rt6_info *rt, void *arg)
1580 {
1581         if (rt->rt6i_flags & RTF_CACHE) {
1582                 RT6_TRACE("pruning clone %p\n", rt);
1583                 return -1;
1584         }
1585 
1586         return 0;
1587 }
1588 
1589 static void fib6_prune_clones(struct net *net, struct fib6_node *fn,
1590                               struct rt6_info *rt)
1591 {
1592         fib6_clean_tree(net, fn, fib6_prune_clone, 1, rt);
1593 }
1594 
1595 /*
1596  *      Garbage collection
1597  */
1598 
1599 static struct fib6_gc_args
1600 {
1601         int                     timeout;
1602         int                     more;
1603 } gc_args;
1604 
1605 static int fib6_age(struct rt6_info *rt, void *arg)
1606 {
1607         unsigned long now = jiffies;
1608 
1609         /*
1610          *      check addrconf expiration here.
1611          *      Routes are expired even if they are in use.
1612          *
1613          *      Also age clones. Note, that clones are aged out
1614          *      only if they are not in use now.
1615          */
1616 
1617         if (rt->rt6i_flags & RTF_EXPIRES && rt->dst.expires) {
1618                 if (time_after(now, rt->dst.expires)) {
1619                         RT6_TRACE("expiring %p\n", rt);
1620                         return -1;
1621                 }
1622                 gc_args.more++;
1623         } else if (rt->rt6i_flags & RTF_CACHE) {
1624                 if (atomic_read(&rt->dst.__refcnt) == 0 &&
1625                     time_after_eq(now, rt->dst.lastuse + gc_args.timeout)) {
1626                         RT6_TRACE("aging clone %p\n", rt);
1627                         return -1;
1628                 } else if (rt->rt6i_flags & RTF_GATEWAY) {
1629                         struct neighbour *neigh;
1630                         __u8 neigh_flags = 0;
1631 
1632                         neigh = dst_neigh_lookup(&rt->dst, &rt->rt6i_gateway);
1633                         if (neigh) {
1634                                 neigh_flags = neigh->flags;
1635                                 neigh_release(neigh);
1636                         }
1637                         if (!(neigh_flags & NTF_ROUTER)) {
1638                                 RT6_TRACE("purging route %p via non-router but gateway\n",
1639                                           rt);
1640                                 return -1;
1641                         }
1642                 }
1643                 gc_args.more++;
1644         }
1645 
1646         return 0;
1647 }
1648 
1649 static DEFINE_SPINLOCK(fib6_gc_lock);
1650 
1651 void fib6_run_gc(unsigned long expires, struct net *net, bool force)
1652 {
1653         unsigned long now;
1654 
1655         if (force) {
1656                 spin_lock_bh(&fib6_gc_lock);
1657         } else if (!spin_trylock_bh(&fib6_gc_lock)) {
1658                 mod_timer(&net->ipv6.ip6_fib_timer, jiffies + HZ);
1659                 return;
1660         }
1661         gc_args.timeout = expires ? (int)expires :
1662                           net->ipv6.sysctl.ip6_rt_gc_interval;
1663 
1664         gc_args.more = icmp6_dst_gc();
1665 
1666         fib6_clean_all(net, fib6_age, 0, NULL);
1667         now = jiffies;
1668         net->ipv6.ip6_rt_last_gc = now;
1669 
1670         if (gc_args.more)
1671                 mod_timer(&net->ipv6.ip6_fib_timer,
1672                           round_jiffies(now
1673                                         + net->ipv6.sysctl.ip6_rt_gc_interval));
1674         else
1675                 del_timer(&net->ipv6.ip6_fib_timer);
1676         spin_unlock_bh(&fib6_gc_lock);
1677 }
1678 
1679 static void fib6_gc_timer_cb(unsigned long arg)
1680 {
1681         fib6_run_gc(0, (struct net *)arg, true);
1682 }
1683 
1684 static int __net_init fib6_net_init(struct net *net)
1685 {
1686         size_t size = sizeof(struct hlist_head) * FIB6_TABLE_HASHSZ;
1687 
1688         setup_timer(&net->ipv6.ip6_fib_timer, fib6_gc_timer_cb, (unsigned long)net);
1689 
1690         net->ipv6.rt6_stats = kzalloc(sizeof(*net->ipv6.rt6_stats), GFP_KERNEL);
1691         if (!net->ipv6.rt6_stats)
1692                 goto out_timer;
1693 
1694         /* Avoid false sharing : Use at least a full cache line */
1695         size = max_t(size_t, size, L1_CACHE_BYTES);
1696 
1697         net->ipv6.fib_table_hash = kzalloc(size, GFP_KERNEL);
1698         if (!net->ipv6.fib_table_hash)
1699                 goto out_rt6_stats;
1700 
1701         net->ipv6.fib6_main_tbl = kzalloc(sizeof(*net->ipv6.fib6_main_tbl),
1702                                           GFP_KERNEL);
1703         if (!net->ipv6.fib6_main_tbl)
1704                 goto out_fib_table_hash;
1705 
1706         net->ipv6.fib6_main_tbl->tb6_id = RT6_TABLE_MAIN;
1707         net->ipv6.fib6_main_tbl->tb6_root.leaf = net->ipv6.ip6_null_entry;
1708         net->ipv6.fib6_main_tbl->tb6_root.fn_flags =
1709                 RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
1710         inet_peer_base_init(&net->ipv6.fib6_main_tbl->tb6_peers);
1711 
1712 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
1713         net->ipv6.fib6_local_tbl = kzalloc(sizeof(*net->ipv6.fib6_local_tbl),
1714                                            GFP_KERNEL);
1715         if (!net->ipv6.fib6_local_tbl)
1716                 goto out_fib6_main_tbl;
1717         net->ipv6.fib6_local_tbl->tb6_id = RT6_TABLE_LOCAL;
1718         net->ipv6.fib6_local_tbl->tb6_root.leaf = net->ipv6.ip6_null_entry;
1719         net->ipv6.fib6_local_tbl->tb6_root.fn_flags =
1720                 RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
1721         inet_peer_base_init(&net->ipv6.fib6_local_tbl->tb6_peers);
1722 #endif
1723         fib6_tables_init(net);
1724 
1725         return 0;
1726 
1727 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
1728 out_fib6_main_tbl:
1729         kfree(net->ipv6.fib6_main_tbl);
1730 #endif
1731 out_fib_table_hash:
1732         kfree(net->ipv6.fib_table_hash);
1733 out_rt6_stats:
1734         kfree(net->ipv6.rt6_stats);
1735 out_timer:
1736         return -ENOMEM;
1737  }
1738 
1739 static void fib6_net_exit(struct net *net)
1740 {
1741         rt6_ifdown(net, NULL);
1742         del_timer_sync(&net->ipv6.ip6_fib_timer);
1743 
1744 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
1745         inetpeer_invalidate_tree(&net->ipv6.fib6_local_tbl->tb6_peers);
1746         kfree(net->ipv6.fib6_local_tbl);
1747 #endif
1748         inetpeer_invalidate_tree(&net->ipv6.fib6_main_tbl->tb6_peers);
1749         kfree(net->ipv6.fib6_main_tbl);
1750         kfree(net->ipv6.fib_table_hash);
1751         kfree(net->ipv6.rt6_stats);
1752 }
1753 
1754 static struct pernet_operations fib6_net_ops = {
1755         .init = fib6_net_init,
1756         .exit = fib6_net_exit,
1757 };
1758 
1759 int __init fib6_init(void)
1760 {
1761         int ret = -ENOMEM;
1762 
1763         fib6_node_kmem = kmem_cache_create("fib6_nodes",
1764                                            sizeof(struct fib6_node),
1765                                            0, SLAB_HWCACHE_ALIGN,
1766                                            NULL);
1767         if (!fib6_node_kmem)
1768                 goto out;
1769 
1770         ret = register_pernet_subsys(&fib6_net_ops);
1771         if (ret)
1772                 goto out_kmem_cache_create;
1773 
1774         ret = __rtnl_register(PF_INET6, RTM_GETROUTE, NULL, inet6_dump_fib,
1775                               NULL);
1776         if (ret)
1777                 goto out_unregister_subsys;
1778 out:
1779         return ret;
1780 
1781 out_unregister_subsys:
1782         unregister_pernet_subsys(&fib6_net_ops);
1783 out_kmem_cache_create:
1784         kmem_cache_destroy(fib6_node_kmem);
1785         goto out;
1786 }
1787 
1788 void fib6_gc_cleanup(void)
1789 {
1790         unregister_pernet_subsys(&fib6_net_ops);
1791         kmem_cache_destroy(fib6_node_kmem);
1792 }
1793 

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