xref: /openbmc/linux/net/ipv6/ip6_fib.c (revision c819e2cf)
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 
36 #include <net/ip6_fib.h>
37 #include <net/ip6_route.h>
38 
39 #define RT6_DEBUG 2
40 
41 #if RT6_DEBUG >= 3
42 #define RT6_TRACE(x...) pr_debug(x)
43 #else
44 #define RT6_TRACE(x...) do { ; } while (0)
45 #endif
46 
47 static struct kmem_cache *fib6_node_kmem __read_mostly;
48 
49 struct fib6_cleaner {
50 	struct fib6_walker w;
51 	struct net *net;
52 	int (*func)(struct rt6_info *, void *arg);
53 	int sernum;
54 	void *arg;
55 };
56 
57 static DEFINE_RWLOCK(fib6_walker_lock);
58 
59 #ifdef CONFIG_IPV6_SUBTREES
60 #define FWS_INIT FWS_S
61 #else
62 #define FWS_INIT FWS_L
63 #endif
64 
65 static void fib6_prune_clones(struct net *net, struct fib6_node *fn);
66 static struct rt6_info *fib6_find_prefix(struct net *net, struct fib6_node *fn);
67 static struct fib6_node *fib6_repair_tree(struct net *net, struct fib6_node *fn);
68 static int fib6_walk(struct fib6_walker *w);
69 static int fib6_walk_continue(struct fib6_walker *w);
70 
71 /*
72  *	A routing update causes an increase of the serial number on the
73  *	affected subtree. This allows for cached routes to be asynchronously
74  *	tested when modifications are made to the destination cache as a
75  *	result of redirects, path MTU changes, etc.
76  */
77 
78 static void fib6_gc_timer_cb(unsigned long arg);
79 
80 static LIST_HEAD(fib6_walkers);
81 #define FOR_WALKERS(w) list_for_each_entry(w, &fib6_walkers, lh)
82 
83 static void fib6_walker_link(struct fib6_walker *w)
84 {
85 	write_lock_bh(&fib6_walker_lock);
86 	list_add(&w->lh, &fib6_walkers);
87 	write_unlock_bh(&fib6_walker_lock);
88 }
89 
90 static void fib6_walker_unlink(struct fib6_walker *w)
91 {
92 	write_lock_bh(&fib6_walker_lock);
93 	list_del(&w->lh);
94 	write_unlock_bh(&fib6_walker_lock);
95 }
96 
97 static int fib6_new_sernum(struct net *net)
98 {
99 	int new, old;
100 
101 	do {
102 		old = atomic_read(&net->ipv6.fib6_sernum);
103 		new = old < INT_MAX ? old + 1 : 1;
104 	} while (atomic_cmpxchg(&net->ipv6.fib6_sernum,
105 				old, new) != old);
106 	return new;
107 }
108 
109 enum {
110 	FIB6_NO_SERNUM_CHANGE = 0,
111 };
112 
113 /*
114  *	Auxiliary address test functions for the radix tree.
115  *
116  *	These assume a 32bit processor (although it will work on
117  *	64bit processors)
118  */
119 
120 /*
121  *	test bit
122  */
123 #if defined(__LITTLE_ENDIAN)
124 # define BITOP_BE32_SWIZZLE	(0x1F & ~7)
125 #else
126 # define BITOP_BE32_SWIZZLE	0
127 #endif
128 
129 static __be32 addr_bit_set(const void *token, int fn_bit)
130 {
131 	const __be32 *addr = token;
132 	/*
133 	 * Here,
134 	 *	1 << ((~fn_bit ^ BITOP_BE32_SWIZZLE) & 0x1f)
135 	 * is optimized version of
136 	 *	htonl(1 << ((~fn_bit)&0x1F))
137 	 * See include/asm-generic/bitops/le.h.
138 	 */
139 	return (__force __be32)(1 << ((~fn_bit ^ BITOP_BE32_SWIZZLE) & 0x1f)) &
140 	       addr[fn_bit >> 5];
141 }
142 
143 static struct fib6_node *node_alloc(void)
144 {
145 	struct fib6_node *fn;
146 
147 	fn = kmem_cache_zalloc(fib6_node_kmem, GFP_ATOMIC);
148 
149 	return fn;
150 }
151 
152 static void node_free(struct fib6_node *fn)
153 {
154 	kmem_cache_free(fib6_node_kmem, fn);
155 }
156 
157 static void rt6_release(struct rt6_info *rt)
158 {
159 	if (atomic_dec_and_test(&rt->rt6i_ref))
160 		dst_free(&rt->dst);
161 }
162 
163 static void fib6_link_table(struct net *net, struct fib6_table *tb)
164 {
165 	unsigned int h;
166 
167 	/*
168 	 * Initialize table lock at a single place to give lockdep a key,
169 	 * tables aren't visible prior to being linked to the list.
170 	 */
171 	rwlock_init(&tb->tb6_lock);
172 
173 	h = tb->tb6_id & (FIB6_TABLE_HASHSZ - 1);
174 
175 	/*
176 	 * No protection necessary, this is the only list mutatation
177 	 * operation, tables never disappear once they exist.
178 	 */
179 	hlist_add_head_rcu(&tb->tb6_hlist, &net->ipv6.fib_table_hash[h]);
180 }
181 
182 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
183 
184 static struct fib6_table *fib6_alloc_table(struct net *net, u32 id)
185 {
186 	struct fib6_table *table;
187 
188 	table = kzalloc(sizeof(*table), GFP_ATOMIC);
189 	if (table) {
190 		table->tb6_id = id;
191 		table->tb6_root.leaf = net->ipv6.ip6_null_entry;
192 		table->tb6_root.fn_flags = RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
193 		inet_peer_base_init(&table->tb6_peers);
194 	}
195 
196 	return table;
197 }
198 
199 struct fib6_table *fib6_new_table(struct net *net, u32 id)
200 {
201 	struct fib6_table *tb;
202 
203 	if (id == 0)
204 		id = RT6_TABLE_MAIN;
205 	tb = fib6_get_table(net, id);
206 	if (tb)
207 		return tb;
208 
209 	tb = fib6_alloc_table(net, id);
210 	if (tb)
211 		fib6_link_table(net, tb);
212 
213 	return tb;
214 }
215 
216 struct fib6_table *fib6_get_table(struct net *net, u32 id)
217 {
218 	struct fib6_table *tb;
219 	struct hlist_head *head;
220 	unsigned int h;
221 
222 	if (id == 0)
223 		id = RT6_TABLE_MAIN;
224 	h = id & (FIB6_TABLE_HASHSZ - 1);
225 	rcu_read_lock();
226 	head = &net->ipv6.fib_table_hash[h];
227 	hlist_for_each_entry_rcu(tb, head, tb6_hlist) {
228 		if (tb->tb6_id == id) {
229 			rcu_read_unlock();
230 			return tb;
231 		}
232 	}
233 	rcu_read_unlock();
234 
235 	return NULL;
236 }
237 
238 static void __net_init fib6_tables_init(struct net *net)
239 {
240 	fib6_link_table(net, net->ipv6.fib6_main_tbl);
241 	fib6_link_table(net, net->ipv6.fib6_local_tbl);
242 }
243 #else
244 
245 struct fib6_table *fib6_new_table(struct net *net, u32 id)
246 {
247 	return fib6_get_table(net, id);
248 }
249 
250 struct fib6_table *fib6_get_table(struct net *net, u32 id)
251 {
252 	  return net->ipv6.fib6_main_tbl;
253 }
254 
255 struct dst_entry *fib6_rule_lookup(struct net *net, struct flowi6 *fl6,
256 				   int flags, pol_lookup_t lookup)
257 {
258 	return (struct dst_entry *) lookup(net, net->ipv6.fib6_main_tbl, fl6, flags);
259 }
260 
261 static void __net_init fib6_tables_init(struct net *net)
262 {
263 	fib6_link_table(net, net->ipv6.fib6_main_tbl);
264 }
265 
266 #endif
267 
268 static int fib6_dump_node(struct fib6_walker *w)
269 {
270 	int res;
271 	struct rt6_info *rt;
272 
273 	for (rt = w->leaf; rt; rt = rt->dst.rt6_next) {
274 		res = rt6_dump_route(rt, w->args);
275 		if (res < 0) {
276 			/* Frame is full, suspend walking */
277 			w->leaf = rt;
278 			return 1;
279 		}
280 		WARN_ON(res == 0);
281 	}
282 	w->leaf = NULL;
283 	return 0;
284 }
285 
286 static void fib6_dump_end(struct netlink_callback *cb)
287 {
288 	struct fib6_walker *w = (void *)cb->args[2];
289 
290 	if (w) {
291 		if (cb->args[4]) {
292 			cb->args[4] = 0;
293 			fib6_walker_unlink(w);
294 		}
295 		cb->args[2] = 0;
296 		kfree(w);
297 	}
298 	cb->done = (void *)cb->args[3];
299 	cb->args[1] = 3;
300 }
301 
302 static int fib6_dump_done(struct netlink_callback *cb)
303 {
304 	fib6_dump_end(cb);
305 	return cb->done ? cb->done(cb) : 0;
306 }
307 
308 static int fib6_dump_table(struct fib6_table *table, struct sk_buff *skb,
309 			   struct netlink_callback *cb)
310 {
311 	struct fib6_walker *w;
312 	int res;
313 
314 	w = (void *)cb->args[2];
315 	w->root = &table->tb6_root;
316 
317 	if (cb->args[4] == 0) {
318 		w->count = 0;
319 		w->skip = 0;
320 
321 		read_lock_bh(&table->tb6_lock);
322 		res = fib6_walk(w);
323 		read_unlock_bh(&table->tb6_lock);
324 		if (res > 0) {
325 			cb->args[4] = 1;
326 			cb->args[5] = w->root->fn_sernum;
327 		}
328 	} else {
329 		if (cb->args[5] != w->root->fn_sernum) {
330 			/* Begin at the root if the tree changed */
331 			cb->args[5] = w->root->fn_sernum;
332 			w->state = FWS_INIT;
333 			w->node = w->root;
334 			w->skip = w->count;
335 		} else
336 			w->skip = 0;
337 
338 		read_lock_bh(&table->tb6_lock);
339 		res = fib6_walk_continue(w);
340 		read_unlock_bh(&table->tb6_lock);
341 		if (res <= 0) {
342 			fib6_walker_unlink(w);
343 			cb->args[4] = 0;
344 		}
345 	}
346 
347 	return res;
348 }
349 
350 static int inet6_dump_fib(struct sk_buff *skb, struct netlink_callback *cb)
351 {
352 	struct net *net = sock_net(skb->sk);
353 	unsigned int h, s_h;
354 	unsigned int e = 0, s_e;
355 	struct rt6_rtnl_dump_arg arg;
356 	struct fib6_walker *w;
357 	struct fib6_table *tb;
358 	struct hlist_head *head;
359 	int res = 0;
360 
361 	s_h = cb->args[0];
362 	s_e = cb->args[1];
363 
364 	w = (void *)cb->args[2];
365 	if (!w) {
366 		/* New dump:
367 		 *
368 		 * 1. hook callback destructor.
369 		 */
370 		cb->args[3] = (long)cb->done;
371 		cb->done = fib6_dump_done;
372 
373 		/*
374 		 * 2. allocate and initialize walker.
375 		 */
376 		w = kzalloc(sizeof(*w), GFP_ATOMIC);
377 		if (!w)
378 			return -ENOMEM;
379 		w->func = fib6_dump_node;
380 		cb->args[2] = (long)w;
381 	}
382 
383 	arg.skb = skb;
384 	arg.cb = cb;
385 	arg.net = net;
386 	w->args = &arg;
387 
388 	rcu_read_lock();
389 	for (h = s_h; h < FIB6_TABLE_HASHSZ; h++, s_e = 0) {
390 		e = 0;
391 		head = &net->ipv6.fib_table_hash[h];
392 		hlist_for_each_entry_rcu(tb, head, tb6_hlist) {
393 			if (e < s_e)
394 				goto next;
395 			res = fib6_dump_table(tb, skb, cb);
396 			if (res != 0)
397 				goto out;
398 next:
399 			e++;
400 		}
401 	}
402 out:
403 	rcu_read_unlock();
404 	cb->args[1] = e;
405 	cb->args[0] = h;
406 
407 	res = res < 0 ? res : skb->len;
408 	if (res <= 0)
409 		fib6_dump_end(cb);
410 	return res;
411 }
412 
413 /*
414  *	Routing Table
415  *
416  *	return the appropriate node for a routing tree "add" operation
417  *	by either creating and inserting or by returning an existing
418  *	node.
419  */
420 
421 static struct fib6_node *fib6_add_1(struct fib6_node *root,
422 				     struct in6_addr *addr, int plen,
423 				     int offset, int allow_create,
424 				     int replace_required, int sernum)
425 {
426 	struct fib6_node *fn, *in, *ln;
427 	struct fib6_node *pn = NULL;
428 	struct rt6key *key;
429 	int	bit;
430 	__be32	dir = 0;
431 
432 	RT6_TRACE("fib6_add_1\n");
433 
434 	/* insert node in tree */
435 
436 	fn = root;
437 
438 	do {
439 		key = (struct rt6key *)((u8 *)fn->leaf + offset);
440 
441 		/*
442 		 *	Prefix match
443 		 */
444 		if (plen < fn->fn_bit ||
445 		    !ipv6_prefix_equal(&key->addr, addr, fn->fn_bit)) {
446 			if (!allow_create) {
447 				if (replace_required) {
448 					pr_warn("Can't replace route, no match found\n");
449 					return ERR_PTR(-ENOENT);
450 				}
451 				pr_warn("NLM_F_CREATE should be set when creating new route\n");
452 			}
453 			goto insert_above;
454 		}
455 
456 		/*
457 		 *	Exact match ?
458 		 */
459 
460 		if (plen == fn->fn_bit) {
461 			/* clean up an intermediate node */
462 			if (!(fn->fn_flags & RTN_RTINFO)) {
463 				rt6_release(fn->leaf);
464 				fn->leaf = NULL;
465 			}
466 
467 			fn->fn_sernum = sernum;
468 
469 			return fn;
470 		}
471 
472 		/*
473 		 *	We have more bits to go
474 		 */
475 
476 		/* Try to walk down on tree. */
477 		fn->fn_sernum = sernum;
478 		dir = addr_bit_set(addr, fn->fn_bit);
479 		pn = fn;
480 		fn = dir ? fn->right : fn->left;
481 	} while (fn);
482 
483 	if (!allow_create) {
484 		/* We should not create new node because
485 		 * NLM_F_REPLACE was specified without NLM_F_CREATE
486 		 * I assume it is safe to require NLM_F_CREATE when
487 		 * REPLACE flag is used! Later we may want to remove the
488 		 * check for replace_required, because according
489 		 * to netlink specification, NLM_F_CREATE
490 		 * MUST be specified if new route is created.
491 		 * That would keep IPv6 consistent with IPv4
492 		 */
493 		if (replace_required) {
494 			pr_warn("Can't replace route, no match found\n");
495 			return ERR_PTR(-ENOENT);
496 		}
497 		pr_warn("NLM_F_CREATE should be set when creating new route\n");
498 	}
499 	/*
500 	 *	We walked to the bottom of tree.
501 	 *	Create new leaf node without children.
502 	 */
503 
504 	ln = node_alloc();
505 
506 	if (!ln)
507 		return ERR_PTR(-ENOMEM);
508 	ln->fn_bit = plen;
509 
510 	ln->parent = pn;
511 	ln->fn_sernum = sernum;
512 
513 	if (dir)
514 		pn->right = ln;
515 	else
516 		pn->left  = ln;
517 
518 	return ln;
519 
520 
521 insert_above:
522 	/*
523 	 * split since we don't have a common prefix anymore or
524 	 * we have a less significant route.
525 	 * we've to insert an intermediate node on the list
526 	 * this new node will point to the one we need to create
527 	 * and the current
528 	 */
529 
530 	pn = fn->parent;
531 
532 	/* find 1st bit in difference between the 2 addrs.
533 
534 	   See comment in __ipv6_addr_diff: bit may be an invalid value,
535 	   but if it is >= plen, the value is ignored in any case.
536 	 */
537 
538 	bit = __ipv6_addr_diff(addr, &key->addr, sizeof(*addr));
539 
540 	/*
541 	 *		(intermediate)[in]
542 	 *	          /	   \
543 	 *	(new leaf node)[ln] (old node)[fn]
544 	 */
545 	if (plen > bit) {
546 		in = node_alloc();
547 		ln = node_alloc();
548 
549 		if (!in || !ln) {
550 			if (in)
551 				node_free(in);
552 			if (ln)
553 				node_free(ln);
554 			return ERR_PTR(-ENOMEM);
555 		}
556 
557 		/*
558 		 * new intermediate node.
559 		 * RTN_RTINFO will
560 		 * be off since that an address that chooses one of
561 		 * the branches would not match less specific routes
562 		 * in the other branch
563 		 */
564 
565 		in->fn_bit = bit;
566 
567 		in->parent = pn;
568 		in->leaf = fn->leaf;
569 		atomic_inc(&in->leaf->rt6i_ref);
570 
571 		in->fn_sernum = sernum;
572 
573 		/* update parent pointer */
574 		if (dir)
575 			pn->right = in;
576 		else
577 			pn->left  = in;
578 
579 		ln->fn_bit = plen;
580 
581 		ln->parent = in;
582 		fn->parent = in;
583 
584 		ln->fn_sernum = sernum;
585 
586 		if (addr_bit_set(addr, bit)) {
587 			in->right = ln;
588 			in->left  = fn;
589 		} else {
590 			in->left  = ln;
591 			in->right = fn;
592 		}
593 	} else { /* plen <= bit */
594 
595 		/*
596 		 *		(new leaf node)[ln]
597 		 *	          /	   \
598 		 *	     (old node)[fn] NULL
599 		 */
600 
601 		ln = node_alloc();
602 
603 		if (!ln)
604 			return ERR_PTR(-ENOMEM);
605 
606 		ln->fn_bit = plen;
607 
608 		ln->parent = pn;
609 
610 		ln->fn_sernum = sernum;
611 
612 		if (dir)
613 			pn->right = ln;
614 		else
615 			pn->left  = ln;
616 
617 		if (addr_bit_set(&key->addr, plen))
618 			ln->right = fn;
619 		else
620 			ln->left  = fn;
621 
622 		fn->parent = ln;
623 	}
624 	return ln;
625 }
626 
627 static bool rt6_qualify_for_ecmp(struct rt6_info *rt)
628 {
629 	return (rt->rt6i_flags & (RTF_GATEWAY|RTF_ADDRCONF|RTF_DYNAMIC)) ==
630 	       RTF_GATEWAY;
631 }
632 
633 static int fib6_commit_metrics(struct dst_entry *dst,
634 			       struct nlattr *mx, int mx_len)
635 {
636 	struct nlattr *nla;
637 	int remaining;
638 	u32 *mp;
639 
640 	if (dst->flags & DST_HOST) {
641 		mp = dst_metrics_write_ptr(dst);
642 	} else {
643 		mp = kzalloc(sizeof(u32) * RTAX_MAX, GFP_ATOMIC);
644 		if (!mp)
645 			return -ENOMEM;
646 		dst_init_metrics(dst, mp, 0);
647 	}
648 
649 	nla_for_each_attr(nla, mx, mx_len, remaining) {
650 		int type = nla_type(nla);
651 
652 		if (type) {
653 			if (type > RTAX_MAX)
654 				return -EINVAL;
655 
656 			mp[type - 1] = nla_get_u32(nla);
657 		}
658 	}
659 	return 0;
660 }
661 
662 static void fib6_purge_rt(struct rt6_info *rt, struct fib6_node *fn,
663 			  struct net *net)
664 {
665 	if (atomic_read(&rt->rt6i_ref) != 1) {
666 		/* This route is used as dummy address holder in some split
667 		 * nodes. It is not leaked, but it still holds other resources,
668 		 * which must be released in time. So, scan ascendant nodes
669 		 * and replace dummy references to this route with references
670 		 * to still alive ones.
671 		 */
672 		while (fn) {
673 			if (!(fn->fn_flags & RTN_RTINFO) && fn->leaf == rt) {
674 				fn->leaf = fib6_find_prefix(net, fn);
675 				atomic_inc(&fn->leaf->rt6i_ref);
676 				rt6_release(rt);
677 			}
678 			fn = fn->parent;
679 		}
680 		/* No more references are possible at this point. */
681 		BUG_ON(atomic_read(&rt->rt6i_ref) != 1);
682 	}
683 }
684 
685 /*
686  *	Insert routing information in a node.
687  */
688 
689 static int fib6_add_rt2node(struct fib6_node *fn, struct rt6_info *rt,
690 			    struct nl_info *info, struct nlattr *mx, int mx_len)
691 {
692 	struct rt6_info *iter = NULL;
693 	struct rt6_info **ins;
694 	int replace = (info->nlh &&
695 		       (info->nlh->nlmsg_flags & NLM_F_REPLACE));
696 	int add = (!info->nlh ||
697 		   (info->nlh->nlmsg_flags & NLM_F_CREATE));
698 	int found = 0;
699 	bool rt_can_ecmp = rt6_qualify_for_ecmp(rt);
700 	int err;
701 
702 	ins = &fn->leaf;
703 
704 	for (iter = fn->leaf; iter; iter = iter->dst.rt6_next) {
705 		/*
706 		 *	Search for duplicates
707 		 */
708 
709 		if (iter->rt6i_metric == rt->rt6i_metric) {
710 			/*
711 			 *	Same priority level
712 			 */
713 			if (info->nlh &&
714 			    (info->nlh->nlmsg_flags & NLM_F_EXCL))
715 				return -EEXIST;
716 			if (replace) {
717 				found++;
718 				break;
719 			}
720 
721 			if (iter->dst.dev == rt->dst.dev &&
722 			    iter->rt6i_idev == rt->rt6i_idev &&
723 			    ipv6_addr_equal(&iter->rt6i_gateway,
724 					    &rt->rt6i_gateway)) {
725 				if (rt->rt6i_nsiblings)
726 					rt->rt6i_nsiblings = 0;
727 				if (!(iter->rt6i_flags & RTF_EXPIRES))
728 					return -EEXIST;
729 				if (!(rt->rt6i_flags & RTF_EXPIRES))
730 					rt6_clean_expires(iter);
731 				else
732 					rt6_set_expires(iter, rt->dst.expires);
733 				return -EEXIST;
734 			}
735 			/* If we have the same destination and the same metric,
736 			 * but not the same gateway, then the route we try to
737 			 * add is sibling to this route, increment our counter
738 			 * of siblings, and later we will add our route to the
739 			 * list.
740 			 * Only static routes (which don't have flag
741 			 * RTF_EXPIRES) are used for ECMPv6.
742 			 *
743 			 * To avoid long list, we only had siblings if the
744 			 * route have a gateway.
745 			 */
746 			if (rt_can_ecmp &&
747 			    rt6_qualify_for_ecmp(iter))
748 				rt->rt6i_nsiblings++;
749 		}
750 
751 		if (iter->rt6i_metric > rt->rt6i_metric)
752 			break;
753 
754 		ins = &iter->dst.rt6_next;
755 	}
756 
757 	/* Reset round-robin state, if necessary */
758 	if (ins == &fn->leaf)
759 		fn->rr_ptr = NULL;
760 
761 	/* Link this route to others same route. */
762 	if (rt->rt6i_nsiblings) {
763 		unsigned int rt6i_nsiblings;
764 		struct rt6_info *sibling, *temp_sibling;
765 
766 		/* Find the first route that have the same metric */
767 		sibling = fn->leaf;
768 		while (sibling) {
769 			if (sibling->rt6i_metric == rt->rt6i_metric &&
770 			    rt6_qualify_for_ecmp(sibling)) {
771 				list_add_tail(&rt->rt6i_siblings,
772 					      &sibling->rt6i_siblings);
773 				break;
774 			}
775 			sibling = sibling->dst.rt6_next;
776 		}
777 		/* For each sibling in the list, increment the counter of
778 		 * siblings. BUG() if counters does not match, list of siblings
779 		 * is broken!
780 		 */
781 		rt6i_nsiblings = 0;
782 		list_for_each_entry_safe(sibling, temp_sibling,
783 					 &rt->rt6i_siblings, rt6i_siblings) {
784 			sibling->rt6i_nsiblings++;
785 			BUG_ON(sibling->rt6i_nsiblings != rt->rt6i_nsiblings);
786 			rt6i_nsiblings++;
787 		}
788 		BUG_ON(rt6i_nsiblings != rt->rt6i_nsiblings);
789 	}
790 
791 	/*
792 	 *	insert node
793 	 */
794 	if (!replace) {
795 		if (!add)
796 			pr_warn("NLM_F_CREATE should be set when creating new route\n");
797 
798 add:
799 		if (mx) {
800 			err = fib6_commit_metrics(&rt->dst, mx, mx_len);
801 			if (err)
802 				return err;
803 		}
804 		rt->dst.rt6_next = iter;
805 		*ins = rt;
806 		rt->rt6i_node = fn;
807 		atomic_inc(&rt->rt6i_ref);
808 		inet6_rt_notify(RTM_NEWROUTE, rt, info);
809 		info->nl_net->ipv6.rt6_stats->fib_rt_entries++;
810 
811 		if (!(fn->fn_flags & RTN_RTINFO)) {
812 			info->nl_net->ipv6.rt6_stats->fib_route_nodes++;
813 			fn->fn_flags |= RTN_RTINFO;
814 		}
815 
816 	} else {
817 		if (!found) {
818 			if (add)
819 				goto add;
820 			pr_warn("NLM_F_REPLACE set, but no existing node found!\n");
821 			return -ENOENT;
822 		}
823 		if (mx) {
824 			err = fib6_commit_metrics(&rt->dst, mx, mx_len);
825 			if (err)
826 				return err;
827 		}
828 		*ins = rt;
829 		rt->rt6i_node = fn;
830 		rt->dst.rt6_next = iter->dst.rt6_next;
831 		atomic_inc(&rt->rt6i_ref);
832 		inet6_rt_notify(RTM_NEWROUTE, rt, info);
833 		if (!(fn->fn_flags & RTN_RTINFO)) {
834 			info->nl_net->ipv6.rt6_stats->fib_route_nodes++;
835 			fn->fn_flags |= RTN_RTINFO;
836 		}
837 		fib6_purge_rt(iter, fn, info->nl_net);
838 		rt6_release(iter);
839 	}
840 
841 	return 0;
842 }
843 
844 static void fib6_start_gc(struct net *net, struct rt6_info *rt)
845 {
846 	if (!timer_pending(&net->ipv6.ip6_fib_timer) &&
847 	    (rt->rt6i_flags & (RTF_EXPIRES | RTF_CACHE)))
848 		mod_timer(&net->ipv6.ip6_fib_timer,
849 			  jiffies + net->ipv6.sysctl.ip6_rt_gc_interval);
850 }
851 
852 void fib6_force_start_gc(struct net *net)
853 {
854 	if (!timer_pending(&net->ipv6.ip6_fib_timer))
855 		mod_timer(&net->ipv6.ip6_fib_timer,
856 			  jiffies + net->ipv6.sysctl.ip6_rt_gc_interval);
857 }
858 
859 /*
860  *	Add routing information to the routing tree.
861  *	<destination addr>/<source addr>
862  *	with source addr info in sub-trees
863  */
864 
865 int fib6_add(struct fib6_node *root, struct rt6_info *rt, struct nl_info *info,
866 	     struct nlattr *mx, int mx_len)
867 {
868 	struct fib6_node *fn, *pn = NULL;
869 	int err = -ENOMEM;
870 	int allow_create = 1;
871 	int replace_required = 0;
872 	int sernum = fib6_new_sernum(info->nl_net);
873 
874 	if (info->nlh) {
875 		if (!(info->nlh->nlmsg_flags & NLM_F_CREATE))
876 			allow_create = 0;
877 		if (info->nlh->nlmsg_flags & NLM_F_REPLACE)
878 			replace_required = 1;
879 	}
880 	if (!allow_create && !replace_required)
881 		pr_warn("RTM_NEWROUTE with no NLM_F_CREATE or NLM_F_REPLACE\n");
882 
883 	fn = fib6_add_1(root, &rt->rt6i_dst.addr, rt->rt6i_dst.plen,
884 			offsetof(struct rt6_info, rt6i_dst), allow_create,
885 			replace_required, sernum);
886 	if (IS_ERR(fn)) {
887 		err = PTR_ERR(fn);
888 		fn = NULL;
889 		goto out;
890 	}
891 
892 	pn = fn;
893 
894 #ifdef CONFIG_IPV6_SUBTREES
895 	if (rt->rt6i_src.plen) {
896 		struct fib6_node *sn;
897 
898 		if (!fn->subtree) {
899 			struct fib6_node *sfn;
900 
901 			/*
902 			 * Create subtree.
903 			 *
904 			 *		fn[main tree]
905 			 *		|
906 			 *		sfn[subtree root]
907 			 *		   \
908 			 *		    sn[new leaf node]
909 			 */
910 
911 			/* Create subtree root node */
912 			sfn = node_alloc();
913 			if (!sfn)
914 				goto st_failure;
915 
916 			sfn->leaf = info->nl_net->ipv6.ip6_null_entry;
917 			atomic_inc(&info->nl_net->ipv6.ip6_null_entry->rt6i_ref);
918 			sfn->fn_flags = RTN_ROOT;
919 			sfn->fn_sernum = sernum;
920 
921 			/* Now add the first leaf node to new subtree */
922 
923 			sn = fib6_add_1(sfn, &rt->rt6i_src.addr,
924 					rt->rt6i_src.plen,
925 					offsetof(struct rt6_info, rt6i_src),
926 					allow_create, replace_required, sernum);
927 
928 			if (IS_ERR(sn)) {
929 				/* If it is failed, discard just allocated
930 				   root, and then (in st_failure) stale node
931 				   in main tree.
932 				 */
933 				node_free(sfn);
934 				err = PTR_ERR(sn);
935 				goto st_failure;
936 			}
937 
938 			/* Now link new subtree to main tree */
939 			sfn->parent = fn;
940 			fn->subtree = sfn;
941 		} else {
942 			sn = fib6_add_1(fn->subtree, &rt->rt6i_src.addr,
943 					rt->rt6i_src.plen,
944 					offsetof(struct rt6_info, rt6i_src),
945 					allow_create, replace_required, sernum);
946 
947 			if (IS_ERR(sn)) {
948 				err = PTR_ERR(sn);
949 				goto st_failure;
950 			}
951 		}
952 
953 		if (!fn->leaf) {
954 			fn->leaf = rt;
955 			atomic_inc(&rt->rt6i_ref);
956 		}
957 		fn = sn;
958 	}
959 #endif
960 
961 	err = fib6_add_rt2node(fn, rt, info, mx, mx_len);
962 	if (!err) {
963 		fib6_start_gc(info->nl_net, rt);
964 		if (!(rt->rt6i_flags & RTF_CACHE))
965 			fib6_prune_clones(info->nl_net, pn);
966 	}
967 
968 out:
969 	if (err) {
970 #ifdef CONFIG_IPV6_SUBTREES
971 		/*
972 		 * If fib6_add_1 has cleared the old leaf pointer in the
973 		 * super-tree leaf node we have to find a new one for it.
974 		 */
975 		if (pn != fn && pn->leaf == rt) {
976 			pn->leaf = NULL;
977 			atomic_dec(&rt->rt6i_ref);
978 		}
979 		if (pn != fn && !pn->leaf && !(pn->fn_flags & RTN_RTINFO)) {
980 			pn->leaf = fib6_find_prefix(info->nl_net, pn);
981 #if RT6_DEBUG >= 2
982 			if (!pn->leaf) {
983 				WARN_ON(pn->leaf == NULL);
984 				pn->leaf = info->nl_net->ipv6.ip6_null_entry;
985 			}
986 #endif
987 			atomic_inc(&pn->leaf->rt6i_ref);
988 		}
989 #endif
990 		dst_free(&rt->dst);
991 	}
992 	return err;
993 
994 #ifdef CONFIG_IPV6_SUBTREES
995 	/* Subtree creation failed, probably main tree node
996 	   is orphan. If it is, shoot it.
997 	 */
998 st_failure:
999 	if (fn && !(fn->fn_flags & (RTN_RTINFO|RTN_ROOT)))
1000 		fib6_repair_tree(info->nl_net, fn);
1001 	dst_free(&rt->dst);
1002 	return err;
1003 #endif
1004 }
1005 
1006 /*
1007  *	Routing tree lookup
1008  *
1009  */
1010 
1011 struct lookup_args {
1012 	int			offset;		/* key offset on rt6_info	*/
1013 	const struct in6_addr	*addr;		/* search key			*/
1014 };
1015 
1016 static struct fib6_node *fib6_lookup_1(struct fib6_node *root,
1017 				       struct lookup_args *args)
1018 {
1019 	struct fib6_node *fn;
1020 	__be32 dir;
1021 
1022 	if (unlikely(args->offset == 0))
1023 		return NULL;
1024 
1025 	/*
1026 	 *	Descend on a tree
1027 	 */
1028 
1029 	fn = root;
1030 
1031 	for (;;) {
1032 		struct fib6_node *next;
1033 
1034 		dir = addr_bit_set(args->addr, fn->fn_bit);
1035 
1036 		next = dir ? fn->right : fn->left;
1037 
1038 		if (next) {
1039 			fn = next;
1040 			continue;
1041 		}
1042 		break;
1043 	}
1044 
1045 	while (fn) {
1046 		if (FIB6_SUBTREE(fn) || fn->fn_flags & RTN_RTINFO) {
1047 			struct rt6key *key;
1048 
1049 			key = (struct rt6key *) ((u8 *) fn->leaf +
1050 						 args->offset);
1051 
1052 			if (ipv6_prefix_equal(&key->addr, args->addr, key->plen)) {
1053 #ifdef CONFIG_IPV6_SUBTREES
1054 				if (fn->subtree) {
1055 					struct fib6_node *sfn;
1056 					sfn = fib6_lookup_1(fn->subtree,
1057 							    args + 1);
1058 					if (!sfn)
1059 						goto backtrack;
1060 					fn = sfn;
1061 				}
1062 #endif
1063 				if (fn->fn_flags & RTN_RTINFO)
1064 					return fn;
1065 			}
1066 		}
1067 #ifdef CONFIG_IPV6_SUBTREES
1068 backtrack:
1069 #endif
1070 		if (fn->fn_flags & RTN_ROOT)
1071 			break;
1072 
1073 		fn = fn->parent;
1074 	}
1075 
1076 	return NULL;
1077 }
1078 
1079 struct fib6_node *fib6_lookup(struct fib6_node *root, const struct in6_addr *daddr,
1080 			      const struct in6_addr *saddr)
1081 {
1082 	struct fib6_node *fn;
1083 	struct lookup_args args[] = {
1084 		{
1085 			.offset = offsetof(struct rt6_info, rt6i_dst),
1086 			.addr = daddr,
1087 		},
1088 #ifdef CONFIG_IPV6_SUBTREES
1089 		{
1090 			.offset = offsetof(struct rt6_info, rt6i_src),
1091 			.addr = saddr,
1092 		},
1093 #endif
1094 		{
1095 			.offset = 0,	/* sentinel */
1096 		}
1097 	};
1098 
1099 	fn = fib6_lookup_1(root, daddr ? args : args + 1);
1100 	if (!fn || fn->fn_flags & RTN_TL_ROOT)
1101 		fn = root;
1102 
1103 	return fn;
1104 }
1105 
1106 /*
1107  *	Get node with specified destination prefix (and source prefix,
1108  *	if subtrees are used)
1109  */
1110 
1111 
1112 static struct fib6_node *fib6_locate_1(struct fib6_node *root,
1113 				       const struct in6_addr *addr,
1114 				       int plen, int offset)
1115 {
1116 	struct fib6_node *fn;
1117 
1118 	for (fn = root; fn ; ) {
1119 		struct rt6key *key = (struct rt6key *)((u8 *)fn->leaf + offset);
1120 
1121 		/*
1122 		 *	Prefix match
1123 		 */
1124 		if (plen < fn->fn_bit ||
1125 		    !ipv6_prefix_equal(&key->addr, addr, fn->fn_bit))
1126 			return NULL;
1127 
1128 		if (plen == fn->fn_bit)
1129 			return fn;
1130 
1131 		/*
1132 		 *	We have more bits to go
1133 		 */
1134 		if (addr_bit_set(addr, fn->fn_bit))
1135 			fn = fn->right;
1136 		else
1137 			fn = fn->left;
1138 	}
1139 	return NULL;
1140 }
1141 
1142 struct fib6_node *fib6_locate(struct fib6_node *root,
1143 			      const struct in6_addr *daddr, int dst_len,
1144 			      const struct in6_addr *saddr, int src_len)
1145 {
1146 	struct fib6_node *fn;
1147 
1148 	fn = fib6_locate_1(root, daddr, dst_len,
1149 			   offsetof(struct rt6_info, rt6i_dst));
1150 
1151 #ifdef CONFIG_IPV6_SUBTREES
1152 	if (src_len) {
1153 		WARN_ON(saddr == NULL);
1154 		if (fn && fn->subtree)
1155 			fn = fib6_locate_1(fn->subtree, saddr, src_len,
1156 					   offsetof(struct rt6_info, rt6i_src));
1157 	}
1158 #endif
1159 
1160 	if (fn && fn->fn_flags & RTN_RTINFO)
1161 		return fn;
1162 
1163 	return NULL;
1164 }
1165 
1166 
1167 /*
1168  *	Deletion
1169  *
1170  */
1171 
1172 static struct rt6_info *fib6_find_prefix(struct net *net, struct fib6_node *fn)
1173 {
1174 	if (fn->fn_flags & RTN_ROOT)
1175 		return net->ipv6.ip6_null_entry;
1176 
1177 	while (fn) {
1178 		if (fn->left)
1179 			return fn->left->leaf;
1180 		if (fn->right)
1181 			return fn->right->leaf;
1182 
1183 		fn = FIB6_SUBTREE(fn);
1184 	}
1185 	return NULL;
1186 }
1187 
1188 /*
1189  *	Called to trim the tree of intermediate nodes when possible. "fn"
1190  *	is the node we want to try and remove.
1191  */
1192 
1193 static struct fib6_node *fib6_repair_tree(struct net *net,
1194 					   struct fib6_node *fn)
1195 {
1196 	int children;
1197 	int nstate;
1198 	struct fib6_node *child, *pn;
1199 	struct fib6_walker *w;
1200 	int iter = 0;
1201 
1202 	for (;;) {
1203 		RT6_TRACE("fixing tree: plen=%d iter=%d\n", fn->fn_bit, iter);
1204 		iter++;
1205 
1206 		WARN_ON(fn->fn_flags & RTN_RTINFO);
1207 		WARN_ON(fn->fn_flags & RTN_TL_ROOT);
1208 		WARN_ON(fn->leaf != NULL);
1209 
1210 		children = 0;
1211 		child = NULL;
1212 		if (fn->right)
1213 			child = fn->right, children |= 1;
1214 		if (fn->left)
1215 			child = fn->left, children |= 2;
1216 
1217 		if (children == 3 || FIB6_SUBTREE(fn)
1218 #ifdef CONFIG_IPV6_SUBTREES
1219 		    /* Subtree root (i.e. fn) may have one child */
1220 		    || (children && fn->fn_flags & RTN_ROOT)
1221 #endif
1222 		    ) {
1223 			fn->leaf = fib6_find_prefix(net, fn);
1224 #if RT6_DEBUG >= 2
1225 			if (!fn->leaf) {
1226 				WARN_ON(!fn->leaf);
1227 				fn->leaf = net->ipv6.ip6_null_entry;
1228 			}
1229 #endif
1230 			atomic_inc(&fn->leaf->rt6i_ref);
1231 			return fn->parent;
1232 		}
1233 
1234 		pn = fn->parent;
1235 #ifdef CONFIG_IPV6_SUBTREES
1236 		if (FIB6_SUBTREE(pn) == fn) {
1237 			WARN_ON(!(fn->fn_flags & RTN_ROOT));
1238 			FIB6_SUBTREE(pn) = NULL;
1239 			nstate = FWS_L;
1240 		} else {
1241 			WARN_ON(fn->fn_flags & RTN_ROOT);
1242 #endif
1243 			if (pn->right == fn)
1244 				pn->right = child;
1245 			else if (pn->left == fn)
1246 				pn->left = child;
1247 #if RT6_DEBUG >= 2
1248 			else
1249 				WARN_ON(1);
1250 #endif
1251 			if (child)
1252 				child->parent = pn;
1253 			nstate = FWS_R;
1254 #ifdef CONFIG_IPV6_SUBTREES
1255 		}
1256 #endif
1257 
1258 		read_lock(&fib6_walker_lock);
1259 		FOR_WALKERS(w) {
1260 			if (!child) {
1261 				if (w->root == fn) {
1262 					w->root = w->node = NULL;
1263 					RT6_TRACE("W %p adjusted by delroot 1\n", w);
1264 				} else if (w->node == fn) {
1265 					RT6_TRACE("W %p adjusted by delnode 1, s=%d/%d\n", w, w->state, nstate);
1266 					w->node = pn;
1267 					w->state = nstate;
1268 				}
1269 			} else {
1270 				if (w->root == fn) {
1271 					w->root = child;
1272 					RT6_TRACE("W %p adjusted by delroot 2\n", w);
1273 				}
1274 				if (w->node == fn) {
1275 					w->node = child;
1276 					if (children&2) {
1277 						RT6_TRACE("W %p adjusted by delnode 2, s=%d\n", w, w->state);
1278 						w->state = w->state >= FWS_R ? FWS_U : FWS_INIT;
1279 					} else {
1280 						RT6_TRACE("W %p adjusted by delnode 2, s=%d\n", w, w->state);
1281 						w->state = w->state >= FWS_C ? FWS_U : FWS_INIT;
1282 					}
1283 				}
1284 			}
1285 		}
1286 		read_unlock(&fib6_walker_lock);
1287 
1288 		node_free(fn);
1289 		if (pn->fn_flags & RTN_RTINFO || FIB6_SUBTREE(pn))
1290 			return pn;
1291 
1292 		rt6_release(pn->leaf);
1293 		pn->leaf = NULL;
1294 		fn = pn;
1295 	}
1296 }
1297 
1298 static void fib6_del_route(struct fib6_node *fn, struct rt6_info **rtp,
1299 			   struct nl_info *info)
1300 {
1301 	struct fib6_walker *w;
1302 	struct rt6_info *rt = *rtp;
1303 	struct net *net = info->nl_net;
1304 
1305 	RT6_TRACE("fib6_del_route\n");
1306 
1307 	/* Unlink it */
1308 	*rtp = rt->dst.rt6_next;
1309 	rt->rt6i_node = NULL;
1310 	net->ipv6.rt6_stats->fib_rt_entries--;
1311 	net->ipv6.rt6_stats->fib_discarded_routes++;
1312 
1313 	/* Reset round-robin state, if necessary */
1314 	if (fn->rr_ptr == rt)
1315 		fn->rr_ptr = NULL;
1316 
1317 	/* Remove this entry from other siblings */
1318 	if (rt->rt6i_nsiblings) {
1319 		struct rt6_info *sibling, *next_sibling;
1320 
1321 		list_for_each_entry_safe(sibling, next_sibling,
1322 					 &rt->rt6i_siblings, rt6i_siblings)
1323 			sibling->rt6i_nsiblings--;
1324 		rt->rt6i_nsiblings = 0;
1325 		list_del_init(&rt->rt6i_siblings);
1326 	}
1327 
1328 	/* Adjust walkers */
1329 	read_lock(&fib6_walker_lock);
1330 	FOR_WALKERS(w) {
1331 		if (w->state == FWS_C && w->leaf == rt) {
1332 			RT6_TRACE("walker %p adjusted by delroute\n", w);
1333 			w->leaf = rt->dst.rt6_next;
1334 			if (!w->leaf)
1335 				w->state = FWS_U;
1336 		}
1337 	}
1338 	read_unlock(&fib6_walker_lock);
1339 
1340 	rt->dst.rt6_next = NULL;
1341 
1342 	/* If it was last route, expunge its radix tree node */
1343 	if (!fn->leaf) {
1344 		fn->fn_flags &= ~RTN_RTINFO;
1345 		net->ipv6.rt6_stats->fib_route_nodes--;
1346 		fn = fib6_repair_tree(net, fn);
1347 	}
1348 
1349 	fib6_purge_rt(rt, fn, net);
1350 
1351 	inet6_rt_notify(RTM_DELROUTE, rt, info);
1352 	rt6_release(rt);
1353 }
1354 
1355 int fib6_del(struct rt6_info *rt, struct nl_info *info)
1356 {
1357 	struct net *net = info->nl_net;
1358 	struct fib6_node *fn = rt->rt6i_node;
1359 	struct rt6_info **rtp;
1360 
1361 #if RT6_DEBUG >= 2
1362 	if (rt->dst.obsolete > 0) {
1363 		WARN_ON(fn != NULL);
1364 		return -ENOENT;
1365 	}
1366 #endif
1367 	if (!fn || rt == net->ipv6.ip6_null_entry)
1368 		return -ENOENT;
1369 
1370 	WARN_ON(!(fn->fn_flags & RTN_RTINFO));
1371 
1372 	if (!(rt->rt6i_flags & RTF_CACHE)) {
1373 		struct fib6_node *pn = fn;
1374 #ifdef CONFIG_IPV6_SUBTREES
1375 		/* clones of this route might be in another subtree */
1376 		if (rt->rt6i_src.plen) {
1377 			while (!(pn->fn_flags & RTN_ROOT))
1378 				pn = pn->parent;
1379 			pn = pn->parent;
1380 		}
1381 #endif
1382 		fib6_prune_clones(info->nl_net, pn);
1383 	}
1384 
1385 	/*
1386 	 *	Walk the leaf entries looking for ourself
1387 	 */
1388 
1389 	for (rtp = &fn->leaf; *rtp; rtp = &(*rtp)->dst.rt6_next) {
1390 		if (*rtp == rt) {
1391 			fib6_del_route(fn, rtp, info);
1392 			return 0;
1393 		}
1394 	}
1395 	return -ENOENT;
1396 }
1397 
1398 /*
1399  *	Tree traversal function.
1400  *
1401  *	Certainly, it is not interrupt safe.
1402  *	However, it is internally reenterable wrt itself and fib6_add/fib6_del.
1403  *	It means, that we can modify tree during walking
1404  *	and use this function for garbage collection, clone pruning,
1405  *	cleaning tree when a device goes down etc. etc.
1406  *
1407  *	It guarantees that every node will be traversed,
1408  *	and that it will be traversed only once.
1409  *
1410  *	Callback function w->func may return:
1411  *	0 -> continue walking.
1412  *	positive value -> walking is suspended (used by tree dumps,
1413  *	and probably by gc, if it will be split to several slices)
1414  *	negative value -> terminate walking.
1415  *
1416  *	The function itself returns:
1417  *	0   -> walk is complete.
1418  *	>0  -> walk is incomplete (i.e. suspended)
1419  *	<0  -> walk is terminated by an error.
1420  */
1421 
1422 static int fib6_walk_continue(struct fib6_walker *w)
1423 {
1424 	struct fib6_node *fn, *pn;
1425 
1426 	for (;;) {
1427 		fn = w->node;
1428 		if (!fn)
1429 			return 0;
1430 
1431 		if (w->prune && fn != w->root &&
1432 		    fn->fn_flags & RTN_RTINFO && w->state < FWS_C) {
1433 			w->state = FWS_C;
1434 			w->leaf = fn->leaf;
1435 		}
1436 		switch (w->state) {
1437 #ifdef CONFIG_IPV6_SUBTREES
1438 		case FWS_S:
1439 			if (FIB6_SUBTREE(fn)) {
1440 				w->node = FIB6_SUBTREE(fn);
1441 				continue;
1442 			}
1443 			w->state = FWS_L;
1444 #endif
1445 		case FWS_L:
1446 			if (fn->left) {
1447 				w->node = fn->left;
1448 				w->state = FWS_INIT;
1449 				continue;
1450 			}
1451 			w->state = FWS_R;
1452 		case FWS_R:
1453 			if (fn->right) {
1454 				w->node = fn->right;
1455 				w->state = FWS_INIT;
1456 				continue;
1457 			}
1458 			w->state = FWS_C;
1459 			w->leaf = fn->leaf;
1460 		case FWS_C:
1461 			if (w->leaf && fn->fn_flags & RTN_RTINFO) {
1462 				int err;
1463 
1464 				if (w->skip) {
1465 					w->skip--;
1466 					goto skip;
1467 				}
1468 
1469 				err = w->func(w);
1470 				if (err)
1471 					return err;
1472 
1473 				w->count++;
1474 				continue;
1475 			}
1476 skip:
1477 			w->state = FWS_U;
1478 		case FWS_U:
1479 			if (fn == w->root)
1480 				return 0;
1481 			pn = fn->parent;
1482 			w->node = pn;
1483 #ifdef CONFIG_IPV6_SUBTREES
1484 			if (FIB6_SUBTREE(pn) == fn) {
1485 				WARN_ON(!(fn->fn_flags & RTN_ROOT));
1486 				w->state = FWS_L;
1487 				continue;
1488 			}
1489 #endif
1490 			if (pn->left == fn) {
1491 				w->state = FWS_R;
1492 				continue;
1493 			}
1494 			if (pn->right == fn) {
1495 				w->state = FWS_C;
1496 				w->leaf = w->node->leaf;
1497 				continue;
1498 			}
1499 #if RT6_DEBUG >= 2
1500 			WARN_ON(1);
1501 #endif
1502 		}
1503 	}
1504 }
1505 
1506 static int fib6_walk(struct fib6_walker *w)
1507 {
1508 	int res;
1509 
1510 	w->state = FWS_INIT;
1511 	w->node = w->root;
1512 
1513 	fib6_walker_link(w);
1514 	res = fib6_walk_continue(w);
1515 	if (res <= 0)
1516 		fib6_walker_unlink(w);
1517 	return res;
1518 }
1519 
1520 static int fib6_clean_node(struct fib6_walker *w)
1521 {
1522 	int res;
1523 	struct rt6_info *rt;
1524 	struct fib6_cleaner *c = container_of(w, struct fib6_cleaner, w);
1525 	struct nl_info info = {
1526 		.nl_net = c->net,
1527 	};
1528 
1529 	if (c->sernum != FIB6_NO_SERNUM_CHANGE &&
1530 	    w->node->fn_sernum != c->sernum)
1531 		w->node->fn_sernum = c->sernum;
1532 
1533 	if (!c->func) {
1534 		WARN_ON_ONCE(c->sernum == FIB6_NO_SERNUM_CHANGE);
1535 		w->leaf = NULL;
1536 		return 0;
1537 	}
1538 
1539 	for (rt = w->leaf; rt; rt = rt->dst.rt6_next) {
1540 		res = c->func(rt, c->arg);
1541 		if (res < 0) {
1542 			w->leaf = rt;
1543 			res = fib6_del(rt, &info);
1544 			if (res) {
1545 #if RT6_DEBUG >= 2
1546 				pr_debug("%s: del failed: rt=%p@%p err=%d\n",
1547 					 __func__, rt, rt->rt6i_node, res);
1548 #endif
1549 				continue;
1550 			}
1551 			return 0;
1552 		}
1553 		WARN_ON(res != 0);
1554 	}
1555 	w->leaf = rt;
1556 	return 0;
1557 }
1558 
1559 /*
1560  *	Convenient frontend to tree walker.
1561  *
1562  *	func is called on each route.
1563  *		It may return -1 -> delete this route.
1564  *		              0  -> continue walking
1565  *
1566  *	prune==1 -> only immediate children of node (certainly,
1567  *	ignoring pure split nodes) will be scanned.
1568  */
1569 
1570 static void fib6_clean_tree(struct net *net, struct fib6_node *root,
1571 			    int (*func)(struct rt6_info *, void *arg),
1572 			    bool prune, int sernum, void *arg)
1573 {
1574 	struct fib6_cleaner c;
1575 
1576 	c.w.root = root;
1577 	c.w.func = fib6_clean_node;
1578 	c.w.prune = prune;
1579 	c.w.count = 0;
1580 	c.w.skip = 0;
1581 	c.func = func;
1582 	c.sernum = sernum;
1583 	c.arg = arg;
1584 	c.net = net;
1585 
1586 	fib6_walk(&c.w);
1587 }
1588 
1589 static void __fib6_clean_all(struct net *net,
1590 			     int (*func)(struct rt6_info *, void *),
1591 			     int sernum, void *arg)
1592 {
1593 	struct fib6_table *table;
1594 	struct hlist_head *head;
1595 	unsigned int h;
1596 
1597 	rcu_read_lock();
1598 	for (h = 0; h < FIB6_TABLE_HASHSZ; h++) {
1599 		head = &net->ipv6.fib_table_hash[h];
1600 		hlist_for_each_entry_rcu(table, head, tb6_hlist) {
1601 			write_lock_bh(&table->tb6_lock);
1602 			fib6_clean_tree(net, &table->tb6_root,
1603 					func, false, sernum, arg);
1604 			write_unlock_bh(&table->tb6_lock);
1605 		}
1606 	}
1607 	rcu_read_unlock();
1608 }
1609 
1610 void fib6_clean_all(struct net *net, int (*func)(struct rt6_info *, void *),
1611 		    void *arg)
1612 {
1613 	__fib6_clean_all(net, func, FIB6_NO_SERNUM_CHANGE, arg);
1614 }
1615 
1616 static int fib6_prune_clone(struct rt6_info *rt, void *arg)
1617 {
1618 	if (rt->rt6i_flags & RTF_CACHE) {
1619 		RT6_TRACE("pruning clone %p\n", rt);
1620 		return -1;
1621 	}
1622 
1623 	return 0;
1624 }
1625 
1626 static void fib6_prune_clones(struct net *net, struct fib6_node *fn)
1627 {
1628 	fib6_clean_tree(net, fn, fib6_prune_clone, true,
1629 			FIB6_NO_SERNUM_CHANGE, NULL);
1630 }
1631 
1632 static void fib6_flush_trees(struct net *net)
1633 {
1634 	int new_sernum = fib6_new_sernum(net);
1635 
1636 	__fib6_clean_all(net, NULL, new_sernum, NULL);
1637 }
1638 
1639 /*
1640  *	Garbage collection
1641  */
1642 
1643 static struct fib6_gc_args
1644 {
1645 	int			timeout;
1646 	int			more;
1647 } gc_args;
1648 
1649 static int fib6_age(struct rt6_info *rt, void *arg)
1650 {
1651 	unsigned long now = jiffies;
1652 
1653 	/*
1654 	 *	check addrconf expiration here.
1655 	 *	Routes are expired even if they are in use.
1656 	 *
1657 	 *	Also age clones. Note, that clones are aged out
1658 	 *	only if they are not in use now.
1659 	 */
1660 
1661 	if (rt->rt6i_flags & RTF_EXPIRES && rt->dst.expires) {
1662 		if (time_after(now, rt->dst.expires)) {
1663 			RT6_TRACE("expiring %p\n", rt);
1664 			return -1;
1665 		}
1666 		gc_args.more++;
1667 	} else if (rt->rt6i_flags & RTF_CACHE) {
1668 		if (atomic_read(&rt->dst.__refcnt) == 0 &&
1669 		    time_after_eq(now, rt->dst.lastuse + gc_args.timeout)) {
1670 			RT6_TRACE("aging clone %p\n", rt);
1671 			return -1;
1672 		} else if (rt->rt6i_flags & RTF_GATEWAY) {
1673 			struct neighbour *neigh;
1674 			__u8 neigh_flags = 0;
1675 
1676 			neigh = dst_neigh_lookup(&rt->dst, &rt->rt6i_gateway);
1677 			if (neigh) {
1678 				neigh_flags = neigh->flags;
1679 				neigh_release(neigh);
1680 			}
1681 			if (!(neigh_flags & NTF_ROUTER)) {
1682 				RT6_TRACE("purging route %p via non-router but gateway\n",
1683 					  rt);
1684 				return -1;
1685 			}
1686 		}
1687 		gc_args.more++;
1688 	}
1689 
1690 	return 0;
1691 }
1692 
1693 static DEFINE_SPINLOCK(fib6_gc_lock);
1694 
1695 void fib6_run_gc(unsigned long expires, struct net *net, bool force)
1696 {
1697 	unsigned long now;
1698 
1699 	if (force) {
1700 		spin_lock_bh(&fib6_gc_lock);
1701 	} else if (!spin_trylock_bh(&fib6_gc_lock)) {
1702 		mod_timer(&net->ipv6.ip6_fib_timer, jiffies + HZ);
1703 		return;
1704 	}
1705 	gc_args.timeout = expires ? (int)expires :
1706 			  net->ipv6.sysctl.ip6_rt_gc_interval;
1707 
1708 	gc_args.more = icmp6_dst_gc();
1709 
1710 	fib6_clean_all(net, fib6_age, NULL);
1711 	now = jiffies;
1712 	net->ipv6.ip6_rt_last_gc = now;
1713 
1714 	if (gc_args.more)
1715 		mod_timer(&net->ipv6.ip6_fib_timer,
1716 			  round_jiffies(now
1717 					+ net->ipv6.sysctl.ip6_rt_gc_interval));
1718 	else
1719 		del_timer(&net->ipv6.ip6_fib_timer);
1720 	spin_unlock_bh(&fib6_gc_lock);
1721 }
1722 
1723 static void fib6_gc_timer_cb(unsigned long arg)
1724 {
1725 	fib6_run_gc(0, (struct net *)arg, true);
1726 }
1727 
1728 static int __net_init fib6_net_init(struct net *net)
1729 {
1730 	size_t size = sizeof(struct hlist_head) * FIB6_TABLE_HASHSZ;
1731 
1732 	setup_timer(&net->ipv6.ip6_fib_timer, fib6_gc_timer_cb, (unsigned long)net);
1733 
1734 	net->ipv6.rt6_stats = kzalloc(sizeof(*net->ipv6.rt6_stats), GFP_KERNEL);
1735 	if (!net->ipv6.rt6_stats)
1736 		goto out_timer;
1737 
1738 	/* Avoid false sharing : Use at least a full cache line */
1739 	size = max_t(size_t, size, L1_CACHE_BYTES);
1740 
1741 	net->ipv6.fib_table_hash = kzalloc(size, GFP_KERNEL);
1742 	if (!net->ipv6.fib_table_hash)
1743 		goto out_rt6_stats;
1744 
1745 	net->ipv6.fib6_main_tbl = kzalloc(sizeof(*net->ipv6.fib6_main_tbl),
1746 					  GFP_KERNEL);
1747 	if (!net->ipv6.fib6_main_tbl)
1748 		goto out_fib_table_hash;
1749 
1750 	net->ipv6.fib6_main_tbl->tb6_id = RT6_TABLE_MAIN;
1751 	net->ipv6.fib6_main_tbl->tb6_root.leaf = net->ipv6.ip6_null_entry;
1752 	net->ipv6.fib6_main_tbl->tb6_root.fn_flags =
1753 		RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
1754 	inet_peer_base_init(&net->ipv6.fib6_main_tbl->tb6_peers);
1755 
1756 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
1757 	net->ipv6.fib6_local_tbl = kzalloc(sizeof(*net->ipv6.fib6_local_tbl),
1758 					   GFP_KERNEL);
1759 	if (!net->ipv6.fib6_local_tbl)
1760 		goto out_fib6_main_tbl;
1761 	net->ipv6.fib6_local_tbl->tb6_id = RT6_TABLE_LOCAL;
1762 	net->ipv6.fib6_local_tbl->tb6_root.leaf = net->ipv6.ip6_null_entry;
1763 	net->ipv6.fib6_local_tbl->tb6_root.fn_flags =
1764 		RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
1765 	inet_peer_base_init(&net->ipv6.fib6_local_tbl->tb6_peers);
1766 #endif
1767 	fib6_tables_init(net);
1768 
1769 	return 0;
1770 
1771 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
1772 out_fib6_main_tbl:
1773 	kfree(net->ipv6.fib6_main_tbl);
1774 #endif
1775 out_fib_table_hash:
1776 	kfree(net->ipv6.fib_table_hash);
1777 out_rt6_stats:
1778 	kfree(net->ipv6.rt6_stats);
1779 out_timer:
1780 	return -ENOMEM;
1781 }
1782 
1783 static void fib6_net_exit(struct net *net)
1784 {
1785 	rt6_ifdown(net, NULL);
1786 	del_timer_sync(&net->ipv6.ip6_fib_timer);
1787 
1788 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
1789 	inetpeer_invalidate_tree(&net->ipv6.fib6_local_tbl->tb6_peers);
1790 	kfree(net->ipv6.fib6_local_tbl);
1791 #endif
1792 	inetpeer_invalidate_tree(&net->ipv6.fib6_main_tbl->tb6_peers);
1793 	kfree(net->ipv6.fib6_main_tbl);
1794 	kfree(net->ipv6.fib_table_hash);
1795 	kfree(net->ipv6.rt6_stats);
1796 }
1797 
1798 static struct pernet_operations fib6_net_ops = {
1799 	.init = fib6_net_init,
1800 	.exit = fib6_net_exit,
1801 };
1802 
1803 int __init fib6_init(void)
1804 {
1805 	int ret = -ENOMEM;
1806 
1807 	fib6_node_kmem = kmem_cache_create("fib6_nodes",
1808 					   sizeof(struct fib6_node),
1809 					   0, SLAB_HWCACHE_ALIGN,
1810 					   NULL);
1811 	if (!fib6_node_kmem)
1812 		goto out;
1813 
1814 	ret = register_pernet_subsys(&fib6_net_ops);
1815 	if (ret)
1816 		goto out_kmem_cache_create;
1817 
1818 	ret = __rtnl_register(PF_INET6, RTM_GETROUTE, NULL, inet6_dump_fib,
1819 			      NULL);
1820 	if (ret)
1821 		goto out_unregister_subsys;
1822 
1823 	__fib6_flush_trees = fib6_flush_trees;
1824 out:
1825 	return ret;
1826 
1827 out_unregister_subsys:
1828 	unregister_pernet_subsys(&fib6_net_ops);
1829 out_kmem_cache_create:
1830 	kmem_cache_destroy(fib6_node_kmem);
1831 	goto out;
1832 }
1833 
1834 void fib6_gc_cleanup(void)
1835 {
1836 	unregister_pernet_subsys(&fib6_net_ops);
1837 	kmem_cache_destroy(fib6_node_kmem);
1838 }
1839 
1840 #ifdef CONFIG_PROC_FS
1841 
1842 struct ipv6_route_iter {
1843 	struct seq_net_private p;
1844 	struct fib6_walker w;
1845 	loff_t skip;
1846 	struct fib6_table *tbl;
1847 	int sernum;
1848 };
1849 
1850 static int ipv6_route_seq_show(struct seq_file *seq, void *v)
1851 {
1852 	struct rt6_info *rt = v;
1853 	struct ipv6_route_iter *iter = seq->private;
1854 
1855 	seq_printf(seq, "%pi6 %02x ", &rt->rt6i_dst.addr, rt->rt6i_dst.plen);
1856 
1857 #ifdef CONFIG_IPV6_SUBTREES
1858 	seq_printf(seq, "%pi6 %02x ", &rt->rt6i_src.addr, rt->rt6i_src.plen);
1859 #else
1860 	seq_puts(seq, "00000000000000000000000000000000 00 ");
1861 #endif
1862 	if (rt->rt6i_flags & RTF_GATEWAY)
1863 		seq_printf(seq, "%pi6", &rt->rt6i_gateway);
1864 	else
1865 		seq_puts(seq, "00000000000000000000000000000000");
1866 
1867 	seq_printf(seq, " %08x %08x %08x %08x %8s\n",
1868 		   rt->rt6i_metric, atomic_read(&rt->dst.__refcnt),
1869 		   rt->dst.__use, rt->rt6i_flags,
1870 		   rt->dst.dev ? rt->dst.dev->name : "");
1871 	iter->w.leaf = NULL;
1872 	return 0;
1873 }
1874 
1875 static int ipv6_route_yield(struct fib6_walker *w)
1876 {
1877 	struct ipv6_route_iter *iter = w->args;
1878 
1879 	if (!iter->skip)
1880 		return 1;
1881 
1882 	do {
1883 		iter->w.leaf = iter->w.leaf->dst.rt6_next;
1884 		iter->skip--;
1885 		if (!iter->skip && iter->w.leaf)
1886 			return 1;
1887 	} while (iter->w.leaf);
1888 
1889 	return 0;
1890 }
1891 
1892 static void ipv6_route_seq_setup_walk(struct ipv6_route_iter *iter)
1893 {
1894 	memset(&iter->w, 0, sizeof(iter->w));
1895 	iter->w.func = ipv6_route_yield;
1896 	iter->w.root = &iter->tbl->tb6_root;
1897 	iter->w.state = FWS_INIT;
1898 	iter->w.node = iter->w.root;
1899 	iter->w.args = iter;
1900 	iter->sernum = iter->w.root->fn_sernum;
1901 	INIT_LIST_HEAD(&iter->w.lh);
1902 	fib6_walker_link(&iter->w);
1903 }
1904 
1905 static struct fib6_table *ipv6_route_seq_next_table(struct fib6_table *tbl,
1906 						    struct net *net)
1907 {
1908 	unsigned int h;
1909 	struct hlist_node *node;
1910 
1911 	if (tbl) {
1912 		h = (tbl->tb6_id & (FIB6_TABLE_HASHSZ - 1)) + 1;
1913 		node = rcu_dereference_bh(hlist_next_rcu(&tbl->tb6_hlist));
1914 	} else {
1915 		h = 0;
1916 		node = NULL;
1917 	}
1918 
1919 	while (!node && h < FIB6_TABLE_HASHSZ) {
1920 		node = rcu_dereference_bh(
1921 			hlist_first_rcu(&net->ipv6.fib_table_hash[h++]));
1922 	}
1923 	return hlist_entry_safe(node, struct fib6_table, tb6_hlist);
1924 }
1925 
1926 static void ipv6_route_check_sernum(struct ipv6_route_iter *iter)
1927 {
1928 	if (iter->sernum != iter->w.root->fn_sernum) {
1929 		iter->sernum = iter->w.root->fn_sernum;
1930 		iter->w.state = FWS_INIT;
1931 		iter->w.node = iter->w.root;
1932 		WARN_ON(iter->w.skip);
1933 		iter->w.skip = iter->w.count;
1934 	}
1935 }
1936 
1937 static void *ipv6_route_seq_next(struct seq_file *seq, void *v, loff_t *pos)
1938 {
1939 	int r;
1940 	struct rt6_info *n;
1941 	struct net *net = seq_file_net(seq);
1942 	struct ipv6_route_iter *iter = seq->private;
1943 
1944 	if (!v)
1945 		goto iter_table;
1946 
1947 	n = ((struct rt6_info *)v)->dst.rt6_next;
1948 	if (n) {
1949 		++*pos;
1950 		return n;
1951 	}
1952 
1953 iter_table:
1954 	ipv6_route_check_sernum(iter);
1955 	read_lock(&iter->tbl->tb6_lock);
1956 	r = fib6_walk_continue(&iter->w);
1957 	read_unlock(&iter->tbl->tb6_lock);
1958 	if (r > 0) {
1959 		if (v)
1960 			++*pos;
1961 		return iter->w.leaf;
1962 	} else if (r < 0) {
1963 		fib6_walker_unlink(&iter->w);
1964 		return NULL;
1965 	}
1966 	fib6_walker_unlink(&iter->w);
1967 
1968 	iter->tbl = ipv6_route_seq_next_table(iter->tbl, net);
1969 	if (!iter->tbl)
1970 		return NULL;
1971 
1972 	ipv6_route_seq_setup_walk(iter);
1973 	goto iter_table;
1974 }
1975 
1976 static void *ipv6_route_seq_start(struct seq_file *seq, loff_t *pos)
1977 	__acquires(RCU_BH)
1978 {
1979 	struct net *net = seq_file_net(seq);
1980 	struct ipv6_route_iter *iter = seq->private;
1981 
1982 	rcu_read_lock_bh();
1983 	iter->tbl = ipv6_route_seq_next_table(NULL, net);
1984 	iter->skip = *pos;
1985 
1986 	if (iter->tbl) {
1987 		ipv6_route_seq_setup_walk(iter);
1988 		return ipv6_route_seq_next(seq, NULL, pos);
1989 	} else {
1990 		return NULL;
1991 	}
1992 }
1993 
1994 static bool ipv6_route_iter_active(struct ipv6_route_iter *iter)
1995 {
1996 	struct fib6_walker *w = &iter->w;
1997 	return w->node && !(w->state == FWS_U && w->node == w->root);
1998 }
1999 
2000 static void ipv6_route_seq_stop(struct seq_file *seq, void *v)
2001 	__releases(RCU_BH)
2002 {
2003 	struct ipv6_route_iter *iter = seq->private;
2004 
2005 	if (ipv6_route_iter_active(iter))
2006 		fib6_walker_unlink(&iter->w);
2007 
2008 	rcu_read_unlock_bh();
2009 }
2010 
2011 static const struct seq_operations ipv6_route_seq_ops = {
2012 	.start	= ipv6_route_seq_start,
2013 	.next	= ipv6_route_seq_next,
2014 	.stop	= ipv6_route_seq_stop,
2015 	.show	= ipv6_route_seq_show
2016 };
2017 
2018 int ipv6_route_open(struct inode *inode, struct file *file)
2019 {
2020 	return seq_open_net(inode, file, &ipv6_route_seq_ops,
2021 			    sizeof(struct ipv6_route_iter));
2022 }
2023 
2024 #endif /* CONFIG_PROC_FS */
2025