xref: /openbmc/linux/net/ipv6/ip6_fib.c (revision 8b235f2f)
1 /*
2  *	Linux INET6 implementation
3  *	Forwarding Information Database
4  *
5  *	Authors:
6  *	Pedro Roque		<roque@di.fc.ul.pt>
7  *
8  *	This program is free software; you can redistribute it and/or
9  *      modify it under the terms of the GNU General Public License
10  *      as published by the Free Software Foundation; either version
11  *      2 of the License, or (at your option) any later version.
12  *
13  *	Changes:
14  *	Yuji SEKIYA @USAGI:	Support default route on router node;
15  *				remove ip6_null_entry from the top of
16  *				routing table.
17  *	Ville Nuorvala:		Fixed routing subtrees.
18  */
19 
20 #define pr_fmt(fmt) "IPv6: " fmt
21 
22 #include <linux/errno.h>
23 #include <linux/types.h>
24 #include <linux/net.h>
25 #include <linux/route.h>
26 #include <linux/netdevice.h>
27 #include <linux/in6.h>
28 #include <linux/init.h>
29 #include <linux/list.h>
30 #include <linux/slab.h>
31 
32 #include <net/ipv6.h>
33 #include <net/ndisc.h>
34 #include <net/addrconf.h>
35 #include <net/lwtunnel.h>
36 
37 #include <net/ip6_fib.h>
38 #include <net/ip6_route.h>
39 
40 #define RT6_DEBUG 2
41 
42 #if RT6_DEBUG >= 3
43 #define RT6_TRACE(x...) pr_debug(x)
44 #else
45 #define RT6_TRACE(x...) do { ; } while (0)
46 #endif
47 
48 static struct kmem_cache *fib6_node_kmem __read_mostly;
49 
50 struct fib6_cleaner {
51 	struct fib6_walker w;
52 	struct net *net;
53 	int (*func)(struct rt6_info *, void *arg);
54 	int sernum;
55 	void *arg;
56 };
57 
58 static DEFINE_RWLOCK(fib6_walker_lock);
59 
60 #ifdef CONFIG_IPV6_SUBTREES
61 #define FWS_INIT FWS_S
62 #else
63 #define FWS_INIT FWS_L
64 #endif
65 
66 static void fib6_prune_clones(struct net *net, struct fib6_node *fn);
67 static struct rt6_info *fib6_find_prefix(struct net *net, struct fib6_node *fn);
68 static struct fib6_node *fib6_repair_tree(struct net *net, struct fib6_node *fn);
69 static int fib6_walk(struct fib6_walker *w);
70 static int fib6_walk_continue(struct fib6_walker *w);
71 
72 /*
73  *	A routing update causes an increase of the serial number on the
74  *	affected subtree. This allows for cached routes to be asynchronously
75  *	tested when modifications are made to the destination cache as a
76  *	result of redirects, path MTU changes, etc.
77  */
78 
79 static void fib6_gc_timer_cb(unsigned long arg);
80 
81 static LIST_HEAD(fib6_walkers);
82 #define FOR_WALKERS(w) list_for_each_entry(w, &fib6_walkers, lh)
83 
84 static void fib6_walker_link(struct fib6_walker *w)
85 {
86 	write_lock_bh(&fib6_walker_lock);
87 	list_add(&w->lh, &fib6_walkers);
88 	write_unlock_bh(&fib6_walker_lock);
89 }
90 
91 static void fib6_walker_unlink(struct fib6_walker *w)
92 {
93 	write_lock_bh(&fib6_walker_lock);
94 	list_del(&w->lh);
95 	write_unlock_bh(&fib6_walker_lock);
96 }
97 
98 static int fib6_new_sernum(struct net *net)
99 {
100 	int new, old;
101 
102 	do {
103 		old = atomic_read(&net->ipv6.fib6_sernum);
104 		new = old < INT_MAX ? old + 1 : 1;
105 	} while (atomic_cmpxchg(&net->ipv6.fib6_sernum,
106 				old, new) != old);
107 	return new;
108 }
109 
110 enum {
111 	FIB6_NO_SERNUM_CHANGE = 0,
112 };
113 
114 /*
115  *	Auxiliary address test functions for the radix tree.
116  *
117  *	These assume a 32bit processor (although it will work on
118  *	64bit processors)
119  */
120 
121 /*
122  *	test bit
123  */
124 #if defined(__LITTLE_ENDIAN)
125 # define BITOP_BE32_SWIZZLE	(0x1F & ~7)
126 #else
127 # define BITOP_BE32_SWIZZLE	0
128 #endif
129 
130 static __be32 addr_bit_set(const void *token, int fn_bit)
131 {
132 	const __be32 *addr = token;
133 	/*
134 	 * Here,
135 	 *	1 << ((~fn_bit ^ BITOP_BE32_SWIZZLE) & 0x1f)
136 	 * is optimized version of
137 	 *	htonl(1 << ((~fn_bit)&0x1F))
138 	 * See include/asm-generic/bitops/le.h.
139 	 */
140 	return (__force __be32)(1 << ((~fn_bit ^ BITOP_BE32_SWIZZLE) & 0x1f)) &
141 	       addr[fn_bit >> 5];
142 }
143 
144 static struct fib6_node *node_alloc(void)
145 {
146 	struct fib6_node *fn;
147 
148 	fn = kmem_cache_zalloc(fib6_node_kmem, GFP_ATOMIC);
149 
150 	return fn;
151 }
152 
153 static void node_free(struct fib6_node *fn)
154 {
155 	kmem_cache_free(fib6_node_kmem, fn);
156 }
157 
158 static void rt6_free_pcpu(struct rt6_info *non_pcpu_rt)
159 {
160 	int cpu;
161 
162 	if (!non_pcpu_rt->rt6i_pcpu)
163 		return;
164 
165 	for_each_possible_cpu(cpu) {
166 		struct rt6_info **ppcpu_rt;
167 		struct rt6_info *pcpu_rt;
168 
169 		ppcpu_rt = per_cpu_ptr(non_pcpu_rt->rt6i_pcpu, cpu);
170 		pcpu_rt = *ppcpu_rt;
171 		if (pcpu_rt) {
172 			dst_free(&pcpu_rt->dst);
173 			*ppcpu_rt = NULL;
174 		}
175 	}
176 
177 	non_pcpu_rt->rt6i_pcpu = NULL;
178 }
179 
180 static void rt6_release(struct rt6_info *rt)
181 {
182 	if (atomic_dec_and_test(&rt->rt6i_ref)) {
183 		rt6_free_pcpu(rt);
184 		dst_free(&rt->dst);
185 	}
186 }
187 
188 static void fib6_link_table(struct net *net, struct fib6_table *tb)
189 {
190 	unsigned int h;
191 
192 	/*
193 	 * Initialize table lock at a single place to give lockdep a key,
194 	 * tables aren't visible prior to being linked to the list.
195 	 */
196 	rwlock_init(&tb->tb6_lock);
197 
198 	h = tb->tb6_id & (FIB6_TABLE_HASHSZ - 1);
199 
200 	/*
201 	 * No protection necessary, this is the only list mutatation
202 	 * operation, tables never disappear once they exist.
203 	 */
204 	hlist_add_head_rcu(&tb->tb6_hlist, &net->ipv6.fib_table_hash[h]);
205 }
206 
207 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
208 
209 static struct fib6_table *fib6_alloc_table(struct net *net, u32 id)
210 {
211 	struct fib6_table *table;
212 
213 	table = kzalloc(sizeof(*table), GFP_ATOMIC);
214 	if (table) {
215 		table->tb6_id = id;
216 		table->tb6_root.leaf = net->ipv6.ip6_null_entry;
217 		table->tb6_root.fn_flags = RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
218 		inet_peer_base_init(&table->tb6_peers);
219 	}
220 
221 	return table;
222 }
223 
224 struct fib6_table *fib6_new_table(struct net *net, u32 id)
225 {
226 	struct fib6_table *tb;
227 
228 	if (id == 0)
229 		id = RT6_TABLE_MAIN;
230 	tb = fib6_get_table(net, id);
231 	if (tb)
232 		return tb;
233 
234 	tb = fib6_alloc_table(net, id);
235 	if (tb)
236 		fib6_link_table(net, tb);
237 
238 	return tb;
239 }
240 
241 struct fib6_table *fib6_get_table(struct net *net, u32 id)
242 {
243 	struct fib6_table *tb;
244 	struct hlist_head *head;
245 	unsigned int h;
246 
247 	if (id == 0)
248 		id = RT6_TABLE_MAIN;
249 	h = id & (FIB6_TABLE_HASHSZ - 1);
250 	rcu_read_lock();
251 	head = &net->ipv6.fib_table_hash[h];
252 	hlist_for_each_entry_rcu(tb, head, tb6_hlist) {
253 		if (tb->tb6_id == id) {
254 			rcu_read_unlock();
255 			return tb;
256 		}
257 	}
258 	rcu_read_unlock();
259 
260 	return NULL;
261 }
262 
263 static void __net_init fib6_tables_init(struct net *net)
264 {
265 	fib6_link_table(net, net->ipv6.fib6_main_tbl);
266 	fib6_link_table(net, net->ipv6.fib6_local_tbl);
267 }
268 #else
269 
270 struct fib6_table *fib6_new_table(struct net *net, u32 id)
271 {
272 	return fib6_get_table(net, id);
273 }
274 
275 struct fib6_table *fib6_get_table(struct net *net, u32 id)
276 {
277 	  return net->ipv6.fib6_main_tbl;
278 }
279 
280 struct dst_entry *fib6_rule_lookup(struct net *net, struct flowi6 *fl6,
281 				   int flags, pol_lookup_t lookup)
282 {
283 	return (struct dst_entry *) lookup(net, net->ipv6.fib6_main_tbl, fl6, flags);
284 }
285 
286 static void __net_init fib6_tables_init(struct net *net)
287 {
288 	fib6_link_table(net, net->ipv6.fib6_main_tbl);
289 }
290 
291 #endif
292 
293 static int fib6_dump_node(struct fib6_walker *w)
294 {
295 	int res;
296 	struct rt6_info *rt;
297 
298 	for (rt = w->leaf; rt; rt = rt->dst.rt6_next) {
299 		res = rt6_dump_route(rt, w->args);
300 		if (res < 0) {
301 			/* Frame is full, suspend walking */
302 			w->leaf = rt;
303 			return 1;
304 		}
305 	}
306 	w->leaf = NULL;
307 	return 0;
308 }
309 
310 static void fib6_dump_end(struct netlink_callback *cb)
311 {
312 	struct fib6_walker *w = (void *)cb->args[2];
313 
314 	if (w) {
315 		if (cb->args[4]) {
316 			cb->args[4] = 0;
317 			fib6_walker_unlink(w);
318 		}
319 		cb->args[2] = 0;
320 		kfree(w);
321 	}
322 	cb->done = (void *)cb->args[3];
323 	cb->args[1] = 3;
324 }
325 
326 static int fib6_dump_done(struct netlink_callback *cb)
327 {
328 	fib6_dump_end(cb);
329 	return cb->done ? cb->done(cb) : 0;
330 }
331 
332 static int fib6_dump_table(struct fib6_table *table, struct sk_buff *skb,
333 			   struct netlink_callback *cb)
334 {
335 	struct fib6_walker *w;
336 	int res;
337 
338 	w = (void *)cb->args[2];
339 	w->root = &table->tb6_root;
340 
341 	if (cb->args[4] == 0) {
342 		w->count = 0;
343 		w->skip = 0;
344 
345 		read_lock_bh(&table->tb6_lock);
346 		res = fib6_walk(w);
347 		read_unlock_bh(&table->tb6_lock);
348 		if (res > 0) {
349 			cb->args[4] = 1;
350 			cb->args[5] = w->root->fn_sernum;
351 		}
352 	} else {
353 		if (cb->args[5] != w->root->fn_sernum) {
354 			/* Begin at the root if the tree changed */
355 			cb->args[5] = w->root->fn_sernum;
356 			w->state = FWS_INIT;
357 			w->node = w->root;
358 			w->skip = w->count;
359 		} else
360 			w->skip = 0;
361 
362 		read_lock_bh(&table->tb6_lock);
363 		res = fib6_walk_continue(w);
364 		read_unlock_bh(&table->tb6_lock);
365 		if (res <= 0) {
366 			fib6_walker_unlink(w);
367 			cb->args[4] = 0;
368 		}
369 	}
370 
371 	return res;
372 }
373 
374 static int inet6_dump_fib(struct sk_buff *skb, struct netlink_callback *cb)
375 {
376 	struct net *net = sock_net(skb->sk);
377 	unsigned int h, s_h;
378 	unsigned int e = 0, s_e;
379 	struct rt6_rtnl_dump_arg arg;
380 	struct fib6_walker *w;
381 	struct fib6_table *tb;
382 	struct hlist_head *head;
383 	int res = 0;
384 
385 	s_h = cb->args[0];
386 	s_e = cb->args[1];
387 
388 	w = (void *)cb->args[2];
389 	if (!w) {
390 		/* New dump:
391 		 *
392 		 * 1. hook callback destructor.
393 		 */
394 		cb->args[3] = (long)cb->done;
395 		cb->done = fib6_dump_done;
396 
397 		/*
398 		 * 2. allocate and initialize walker.
399 		 */
400 		w = kzalloc(sizeof(*w), GFP_ATOMIC);
401 		if (!w)
402 			return -ENOMEM;
403 		w->func = fib6_dump_node;
404 		cb->args[2] = (long)w;
405 	}
406 
407 	arg.skb = skb;
408 	arg.cb = cb;
409 	arg.net = net;
410 	w->args = &arg;
411 
412 	rcu_read_lock();
413 	for (h = s_h; h < FIB6_TABLE_HASHSZ; h++, s_e = 0) {
414 		e = 0;
415 		head = &net->ipv6.fib_table_hash[h];
416 		hlist_for_each_entry_rcu(tb, head, tb6_hlist) {
417 			if (e < s_e)
418 				goto next;
419 			res = fib6_dump_table(tb, skb, cb);
420 			if (res != 0)
421 				goto out;
422 next:
423 			e++;
424 		}
425 	}
426 out:
427 	rcu_read_unlock();
428 	cb->args[1] = e;
429 	cb->args[0] = h;
430 
431 	res = res < 0 ? res : skb->len;
432 	if (res <= 0)
433 		fib6_dump_end(cb);
434 	return res;
435 }
436 
437 /*
438  *	Routing Table
439  *
440  *	return the appropriate node for a routing tree "add" operation
441  *	by either creating and inserting or by returning an existing
442  *	node.
443  */
444 
445 static struct fib6_node *fib6_add_1(struct fib6_node *root,
446 				     struct in6_addr *addr, int plen,
447 				     int offset, int allow_create,
448 				     int replace_required, int sernum)
449 {
450 	struct fib6_node *fn, *in, *ln;
451 	struct fib6_node *pn = NULL;
452 	struct rt6key *key;
453 	int	bit;
454 	__be32	dir = 0;
455 
456 	RT6_TRACE("fib6_add_1\n");
457 
458 	/* insert node in tree */
459 
460 	fn = root;
461 
462 	do {
463 		key = (struct rt6key *)((u8 *)fn->leaf + offset);
464 
465 		/*
466 		 *	Prefix match
467 		 */
468 		if (plen < fn->fn_bit ||
469 		    !ipv6_prefix_equal(&key->addr, addr, fn->fn_bit)) {
470 			if (!allow_create) {
471 				if (replace_required) {
472 					pr_warn("Can't replace route, no match found\n");
473 					return ERR_PTR(-ENOENT);
474 				}
475 				pr_warn("NLM_F_CREATE should be set when creating new route\n");
476 			}
477 			goto insert_above;
478 		}
479 
480 		/*
481 		 *	Exact match ?
482 		 */
483 
484 		if (plen == fn->fn_bit) {
485 			/* clean up an intermediate node */
486 			if (!(fn->fn_flags & RTN_RTINFO)) {
487 				rt6_release(fn->leaf);
488 				fn->leaf = NULL;
489 			}
490 
491 			fn->fn_sernum = sernum;
492 
493 			return fn;
494 		}
495 
496 		/*
497 		 *	We have more bits to go
498 		 */
499 
500 		/* Try to walk down on tree. */
501 		fn->fn_sernum = sernum;
502 		dir = addr_bit_set(addr, fn->fn_bit);
503 		pn = fn;
504 		fn = dir ? fn->right : fn->left;
505 	} while (fn);
506 
507 	if (!allow_create) {
508 		/* We should not create new node because
509 		 * NLM_F_REPLACE was specified without NLM_F_CREATE
510 		 * I assume it is safe to require NLM_F_CREATE when
511 		 * REPLACE flag is used! Later we may want to remove the
512 		 * check for replace_required, because according
513 		 * to netlink specification, NLM_F_CREATE
514 		 * MUST be specified if new route is created.
515 		 * That would keep IPv6 consistent with IPv4
516 		 */
517 		if (replace_required) {
518 			pr_warn("Can't replace route, no match found\n");
519 			return ERR_PTR(-ENOENT);
520 		}
521 		pr_warn("NLM_F_CREATE should be set when creating new route\n");
522 	}
523 	/*
524 	 *	We walked to the bottom of tree.
525 	 *	Create new leaf node without children.
526 	 */
527 
528 	ln = node_alloc();
529 
530 	if (!ln)
531 		return ERR_PTR(-ENOMEM);
532 	ln->fn_bit = plen;
533 
534 	ln->parent = pn;
535 	ln->fn_sernum = sernum;
536 
537 	if (dir)
538 		pn->right = ln;
539 	else
540 		pn->left  = ln;
541 
542 	return ln;
543 
544 
545 insert_above:
546 	/*
547 	 * split since we don't have a common prefix anymore or
548 	 * we have a less significant route.
549 	 * we've to insert an intermediate node on the list
550 	 * this new node will point to the one we need to create
551 	 * and the current
552 	 */
553 
554 	pn = fn->parent;
555 
556 	/* find 1st bit in difference between the 2 addrs.
557 
558 	   See comment in __ipv6_addr_diff: bit may be an invalid value,
559 	   but if it is >= plen, the value is ignored in any case.
560 	 */
561 
562 	bit = __ipv6_addr_diff(addr, &key->addr, sizeof(*addr));
563 
564 	/*
565 	 *		(intermediate)[in]
566 	 *	          /	   \
567 	 *	(new leaf node)[ln] (old node)[fn]
568 	 */
569 	if (plen > bit) {
570 		in = node_alloc();
571 		ln = node_alloc();
572 
573 		if (!in || !ln) {
574 			if (in)
575 				node_free(in);
576 			if (ln)
577 				node_free(ln);
578 			return ERR_PTR(-ENOMEM);
579 		}
580 
581 		/*
582 		 * new intermediate node.
583 		 * RTN_RTINFO will
584 		 * be off since that an address that chooses one of
585 		 * the branches would not match less specific routes
586 		 * in the other branch
587 		 */
588 
589 		in->fn_bit = bit;
590 
591 		in->parent = pn;
592 		in->leaf = fn->leaf;
593 		atomic_inc(&in->leaf->rt6i_ref);
594 
595 		in->fn_sernum = sernum;
596 
597 		/* update parent pointer */
598 		if (dir)
599 			pn->right = in;
600 		else
601 			pn->left  = in;
602 
603 		ln->fn_bit = plen;
604 
605 		ln->parent = in;
606 		fn->parent = in;
607 
608 		ln->fn_sernum = sernum;
609 
610 		if (addr_bit_set(addr, bit)) {
611 			in->right = ln;
612 			in->left  = fn;
613 		} else {
614 			in->left  = ln;
615 			in->right = fn;
616 		}
617 	} else { /* plen <= bit */
618 
619 		/*
620 		 *		(new leaf node)[ln]
621 		 *	          /	   \
622 		 *	     (old node)[fn] NULL
623 		 */
624 
625 		ln = node_alloc();
626 
627 		if (!ln)
628 			return ERR_PTR(-ENOMEM);
629 
630 		ln->fn_bit = plen;
631 
632 		ln->parent = pn;
633 
634 		ln->fn_sernum = sernum;
635 
636 		if (dir)
637 			pn->right = ln;
638 		else
639 			pn->left  = ln;
640 
641 		if (addr_bit_set(&key->addr, plen))
642 			ln->right = fn;
643 		else
644 			ln->left  = fn;
645 
646 		fn->parent = ln;
647 	}
648 	return ln;
649 }
650 
651 static bool rt6_qualify_for_ecmp(struct rt6_info *rt)
652 {
653 	return (rt->rt6i_flags & (RTF_GATEWAY|RTF_ADDRCONF|RTF_DYNAMIC)) ==
654 	       RTF_GATEWAY;
655 }
656 
657 static void fib6_copy_metrics(u32 *mp, const struct mx6_config *mxc)
658 {
659 	int i;
660 
661 	for (i = 0; i < RTAX_MAX; i++) {
662 		if (test_bit(i, mxc->mx_valid))
663 			mp[i] = mxc->mx[i];
664 	}
665 }
666 
667 static int fib6_commit_metrics(struct dst_entry *dst, struct mx6_config *mxc)
668 {
669 	if (!mxc->mx)
670 		return 0;
671 
672 	if (dst->flags & DST_HOST) {
673 		u32 *mp = dst_metrics_write_ptr(dst);
674 
675 		if (unlikely(!mp))
676 			return -ENOMEM;
677 
678 		fib6_copy_metrics(mp, mxc);
679 	} else {
680 		dst_init_metrics(dst, mxc->mx, false);
681 
682 		/* We've stolen mx now. */
683 		mxc->mx = NULL;
684 	}
685 
686 	return 0;
687 }
688 
689 static void fib6_purge_rt(struct rt6_info *rt, struct fib6_node *fn,
690 			  struct net *net)
691 {
692 	if (atomic_read(&rt->rt6i_ref) != 1) {
693 		/* This route is used as dummy address holder in some split
694 		 * nodes. It is not leaked, but it still holds other resources,
695 		 * which must be released in time. So, scan ascendant nodes
696 		 * and replace dummy references to this route with references
697 		 * to still alive ones.
698 		 */
699 		while (fn) {
700 			if (!(fn->fn_flags & RTN_RTINFO) && fn->leaf == rt) {
701 				fn->leaf = fib6_find_prefix(net, fn);
702 				atomic_inc(&fn->leaf->rt6i_ref);
703 				rt6_release(rt);
704 			}
705 			fn = fn->parent;
706 		}
707 		/* No more references are possible at this point. */
708 		BUG_ON(atomic_read(&rt->rt6i_ref) != 1);
709 	}
710 }
711 
712 /*
713  *	Insert routing information in a node.
714  */
715 
716 static int fib6_add_rt2node(struct fib6_node *fn, struct rt6_info *rt,
717 			    struct nl_info *info, struct mx6_config *mxc)
718 {
719 	struct rt6_info *iter = NULL;
720 	struct rt6_info **ins;
721 	struct rt6_info **fallback_ins = NULL;
722 	int replace = (info->nlh &&
723 		       (info->nlh->nlmsg_flags & NLM_F_REPLACE));
724 	int add = (!info->nlh ||
725 		   (info->nlh->nlmsg_flags & NLM_F_CREATE));
726 	int found = 0;
727 	bool rt_can_ecmp = rt6_qualify_for_ecmp(rt);
728 	int err;
729 
730 	ins = &fn->leaf;
731 
732 	for (iter = fn->leaf; iter; iter = iter->dst.rt6_next) {
733 		/*
734 		 *	Search for duplicates
735 		 */
736 
737 		if (iter->rt6i_metric == rt->rt6i_metric) {
738 			/*
739 			 *	Same priority level
740 			 */
741 			if (info->nlh &&
742 			    (info->nlh->nlmsg_flags & NLM_F_EXCL))
743 				return -EEXIST;
744 			if (replace) {
745 				if (rt_can_ecmp == rt6_qualify_for_ecmp(iter)) {
746 					found++;
747 					break;
748 				}
749 				if (rt_can_ecmp)
750 					fallback_ins = fallback_ins ?: ins;
751 				goto next_iter;
752 			}
753 
754 			if (iter->dst.dev == rt->dst.dev &&
755 			    iter->rt6i_idev == rt->rt6i_idev &&
756 			    ipv6_addr_equal(&iter->rt6i_gateway,
757 					    &rt->rt6i_gateway)) {
758 				if (rt->rt6i_nsiblings)
759 					rt->rt6i_nsiblings = 0;
760 				if (!(iter->rt6i_flags & RTF_EXPIRES))
761 					return -EEXIST;
762 				if (!(rt->rt6i_flags & RTF_EXPIRES))
763 					rt6_clean_expires(iter);
764 				else
765 					rt6_set_expires(iter, rt->dst.expires);
766 				iter->rt6i_pmtu = rt->rt6i_pmtu;
767 				return -EEXIST;
768 			}
769 			/* If we have the same destination and the same metric,
770 			 * but not the same gateway, then the route we try to
771 			 * add is sibling to this route, increment our counter
772 			 * of siblings, and later we will add our route to the
773 			 * list.
774 			 * Only static routes (which don't have flag
775 			 * RTF_EXPIRES) are used for ECMPv6.
776 			 *
777 			 * To avoid long list, we only had siblings if the
778 			 * route have a gateway.
779 			 */
780 			if (rt_can_ecmp &&
781 			    rt6_qualify_for_ecmp(iter))
782 				rt->rt6i_nsiblings++;
783 		}
784 
785 		if (iter->rt6i_metric > rt->rt6i_metric)
786 			break;
787 
788 next_iter:
789 		ins = &iter->dst.rt6_next;
790 	}
791 
792 	if (fallback_ins && !found) {
793 		/* No ECMP-able route found, replace first non-ECMP one */
794 		ins = fallback_ins;
795 		iter = *ins;
796 		found++;
797 	}
798 
799 	/* Reset round-robin state, if necessary */
800 	if (ins == &fn->leaf)
801 		fn->rr_ptr = NULL;
802 
803 	/* Link this route to others same route. */
804 	if (rt->rt6i_nsiblings) {
805 		unsigned int rt6i_nsiblings;
806 		struct rt6_info *sibling, *temp_sibling;
807 
808 		/* Find the first route that have the same metric */
809 		sibling = fn->leaf;
810 		while (sibling) {
811 			if (sibling->rt6i_metric == rt->rt6i_metric &&
812 			    rt6_qualify_for_ecmp(sibling)) {
813 				list_add_tail(&rt->rt6i_siblings,
814 					      &sibling->rt6i_siblings);
815 				break;
816 			}
817 			sibling = sibling->dst.rt6_next;
818 		}
819 		/* For each sibling in the list, increment the counter of
820 		 * siblings. BUG() if counters does not match, list of siblings
821 		 * is broken!
822 		 */
823 		rt6i_nsiblings = 0;
824 		list_for_each_entry_safe(sibling, temp_sibling,
825 					 &rt->rt6i_siblings, rt6i_siblings) {
826 			sibling->rt6i_nsiblings++;
827 			BUG_ON(sibling->rt6i_nsiblings != rt->rt6i_nsiblings);
828 			rt6i_nsiblings++;
829 		}
830 		BUG_ON(rt6i_nsiblings != rt->rt6i_nsiblings);
831 	}
832 
833 	/*
834 	 *	insert node
835 	 */
836 	if (!replace) {
837 		if (!add)
838 			pr_warn("NLM_F_CREATE should be set when creating new route\n");
839 
840 add:
841 		err = fib6_commit_metrics(&rt->dst, mxc);
842 		if (err)
843 			return err;
844 
845 		rt->dst.rt6_next = iter;
846 		*ins = rt;
847 		rt->rt6i_node = fn;
848 		atomic_inc(&rt->rt6i_ref);
849 		inet6_rt_notify(RTM_NEWROUTE, rt, info);
850 		info->nl_net->ipv6.rt6_stats->fib_rt_entries++;
851 
852 		if (!(fn->fn_flags & RTN_RTINFO)) {
853 			info->nl_net->ipv6.rt6_stats->fib_route_nodes++;
854 			fn->fn_flags |= RTN_RTINFO;
855 		}
856 
857 	} else {
858 		int nsiblings;
859 
860 		if (!found) {
861 			if (add)
862 				goto add;
863 			pr_warn("NLM_F_REPLACE set, but no existing node found!\n");
864 			return -ENOENT;
865 		}
866 
867 		err = fib6_commit_metrics(&rt->dst, mxc);
868 		if (err)
869 			return err;
870 
871 		*ins = rt;
872 		rt->rt6i_node = fn;
873 		rt->dst.rt6_next = iter->dst.rt6_next;
874 		atomic_inc(&rt->rt6i_ref);
875 		inet6_rt_notify(RTM_NEWROUTE, rt, info);
876 		if (!(fn->fn_flags & RTN_RTINFO)) {
877 			info->nl_net->ipv6.rt6_stats->fib_route_nodes++;
878 			fn->fn_flags |= RTN_RTINFO;
879 		}
880 		nsiblings = iter->rt6i_nsiblings;
881 		fib6_purge_rt(iter, fn, info->nl_net);
882 		rt6_release(iter);
883 
884 		if (nsiblings) {
885 			/* Replacing an ECMP route, remove all siblings */
886 			ins = &rt->dst.rt6_next;
887 			iter = *ins;
888 			while (iter) {
889 				if (rt6_qualify_for_ecmp(iter)) {
890 					*ins = iter->dst.rt6_next;
891 					fib6_purge_rt(iter, fn, info->nl_net);
892 					rt6_release(iter);
893 					nsiblings--;
894 				} else {
895 					ins = &iter->dst.rt6_next;
896 				}
897 				iter = *ins;
898 			}
899 			WARN_ON(nsiblings != 0);
900 		}
901 	}
902 
903 	return 0;
904 }
905 
906 static void fib6_start_gc(struct net *net, struct rt6_info *rt)
907 {
908 	if (!timer_pending(&net->ipv6.ip6_fib_timer) &&
909 	    (rt->rt6i_flags & (RTF_EXPIRES | RTF_CACHE)))
910 		mod_timer(&net->ipv6.ip6_fib_timer,
911 			  jiffies + net->ipv6.sysctl.ip6_rt_gc_interval);
912 }
913 
914 void fib6_force_start_gc(struct net *net)
915 {
916 	if (!timer_pending(&net->ipv6.ip6_fib_timer))
917 		mod_timer(&net->ipv6.ip6_fib_timer,
918 			  jiffies + net->ipv6.sysctl.ip6_rt_gc_interval);
919 }
920 
921 /*
922  *	Add routing information to the routing tree.
923  *	<destination addr>/<source addr>
924  *	with source addr info in sub-trees
925  */
926 
927 int fib6_add(struct fib6_node *root, struct rt6_info *rt,
928 	     struct nl_info *info, struct mx6_config *mxc)
929 {
930 	struct fib6_node *fn, *pn = NULL;
931 	int err = -ENOMEM;
932 	int allow_create = 1;
933 	int replace_required = 0;
934 	int sernum = fib6_new_sernum(info->nl_net);
935 
936 	if (info->nlh) {
937 		if (!(info->nlh->nlmsg_flags & NLM_F_CREATE))
938 			allow_create = 0;
939 		if (info->nlh->nlmsg_flags & NLM_F_REPLACE)
940 			replace_required = 1;
941 	}
942 	if (!allow_create && !replace_required)
943 		pr_warn("RTM_NEWROUTE with no NLM_F_CREATE or NLM_F_REPLACE\n");
944 
945 	fn = fib6_add_1(root, &rt->rt6i_dst.addr, rt->rt6i_dst.plen,
946 			offsetof(struct rt6_info, rt6i_dst), allow_create,
947 			replace_required, sernum);
948 	if (IS_ERR(fn)) {
949 		err = PTR_ERR(fn);
950 		fn = NULL;
951 		goto out;
952 	}
953 
954 	pn = fn;
955 
956 #ifdef CONFIG_IPV6_SUBTREES
957 	if (rt->rt6i_src.plen) {
958 		struct fib6_node *sn;
959 
960 		if (!fn->subtree) {
961 			struct fib6_node *sfn;
962 
963 			/*
964 			 * Create subtree.
965 			 *
966 			 *		fn[main tree]
967 			 *		|
968 			 *		sfn[subtree root]
969 			 *		   \
970 			 *		    sn[new leaf node]
971 			 */
972 
973 			/* Create subtree root node */
974 			sfn = node_alloc();
975 			if (!sfn)
976 				goto st_failure;
977 
978 			sfn->leaf = info->nl_net->ipv6.ip6_null_entry;
979 			atomic_inc(&info->nl_net->ipv6.ip6_null_entry->rt6i_ref);
980 			sfn->fn_flags = RTN_ROOT;
981 			sfn->fn_sernum = sernum;
982 
983 			/* Now add the first leaf node to new subtree */
984 
985 			sn = fib6_add_1(sfn, &rt->rt6i_src.addr,
986 					rt->rt6i_src.plen,
987 					offsetof(struct rt6_info, rt6i_src),
988 					allow_create, replace_required, sernum);
989 
990 			if (IS_ERR(sn)) {
991 				/* If it is failed, discard just allocated
992 				   root, and then (in st_failure) stale node
993 				   in main tree.
994 				 */
995 				node_free(sfn);
996 				err = PTR_ERR(sn);
997 				goto st_failure;
998 			}
999 
1000 			/* Now link new subtree to main tree */
1001 			sfn->parent = fn;
1002 			fn->subtree = sfn;
1003 		} else {
1004 			sn = fib6_add_1(fn->subtree, &rt->rt6i_src.addr,
1005 					rt->rt6i_src.plen,
1006 					offsetof(struct rt6_info, rt6i_src),
1007 					allow_create, replace_required, sernum);
1008 
1009 			if (IS_ERR(sn)) {
1010 				err = PTR_ERR(sn);
1011 				goto st_failure;
1012 			}
1013 		}
1014 
1015 		if (!fn->leaf) {
1016 			fn->leaf = rt;
1017 			atomic_inc(&rt->rt6i_ref);
1018 		}
1019 		fn = sn;
1020 	}
1021 #endif
1022 
1023 	err = fib6_add_rt2node(fn, rt, info, mxc);
1024 	if (!err) {
1025 		fib6_start_gc(info->nl_net, rt);
1026 		if (!(rt->rt6i_flags & RTF_CACHE))
1027 			fib6_prune_clones(info->nl_net, pn);
1028 	}
1029 
1030 out:
1031 	if (err) {
1032 #ifdef CONFIG_IPV6_SUBTREES
1033 		/*
1034 		 * If fib6_add_1 has cleared the old leaf pointer in the
1035 		 * super-tree leaf node we have to find a new one for it.
1036 		 */
1037 		if (pn != fn && pn->leaf == rt) {
1038 			pn->leaf = NULL;
1039 			atomic_dec(&rt->rt6i_ref);
1040 		}
1041 		if (pn != fn && !pn->leaf && !(pn->fn_flags & RTN_RTINFO)) {
1042 			pn->leaf = fib6_find_prefix(info->nl_net, pn);
1043 #if RT6_DEBUG >= 2
1044 			if (!pn->leaf) {
1045 				WARN_ON(pn->leaf == NULL);
1046 				pn->leaf = info->nl_net->ipv6.ip6_null_entry;
1047 			}
1048 #endif
1049 			atomic_inc(&pn->leaf->rt6i_ref);
1050 		}
1051 #endif
1052 		dst_free(&rt->dst);
1053 	}
1054 	return err;
1055 
1056 #ifdef CONFIG_IPV6_SUBTREES
1057 	/* Subtree creation failed, probably main tree node
1058 	   is orphan. If it is, shoot it.
1059 	 */
1060 st_failure:
1061 	if (fn && !(fn->fn_flags & (RTN_RTINFO|RTN_ROOT)))
1062 		fib6_repair_tree(info->nl_net, fn);
1063 	dst_free(&rt->dst);
1064 	return err;
1065 #endif
1066 }
1067 
1068 /*
1069  *	Routing tree lookup
1070  *
1071  */
1072 
1073 struct lookup_args {
1074 	int			offset;		/* key offset on rt6_info	*/
1075 	const struct in6_addr	*addr;		/* search key			*/
1076 };
1077 
1078 static struct fib6_node *fib6_lookup_1(struct fib6_node *root,
1079 				       struct lookup_args *args)
1080 {
1081 	struct fib6_node *fn;
1082 	__be32 dir;
1083 
1084 	if (unlikely(args->offset == 0))
1085 		return NULL;
1086 
1087 	/*
1088 	 *	Descend on a tree
1089 	 */
1090 
1091 	fn = root;
1092 
1093 	for (;;) {
1094 		struct fib6_node *next;
1095 
1096 		dir = addr_bit_set(args->addr, fn->fn_bit);
1097 
1098 		next = dir ? fn->right : fn->left;
1099 
1100 		if (next) {
1101 			fn = next;
1102 			continue;
1103 		}
1104 		break;
1105 	}
1106 
1107 	while (fn) {
1108 		if (FIB6_SUBTREE(fn) || fn->fn_flags & RTN_RTINFO) {
1109 			struct rt6key *key;
1110 
1111 			key = (struct rt6key *) ((u8 *) fn->leaf +
1112 						 args->offset);
1113 
1114 			if (ipv6_prefix_equal(&key->addr, args->addr, key->plen)) {
1115 #ifdef CONFIG_IPV6_SUBTREES
1116 				if (fn->subtree) {
1117 					struct fib6_node *sfn;
1118 					sfn = fib6_lookup_1(fn->subtree,
1119 							    args + 1);
1120 					if (!sfn)
1121 						goto backtrack;
1122 					fn = sfn;
1123 				}
1124 #endif
1125 				if (fn->fn_flags & RTN_RTINFO)
1126 					return fn;
1127 			}
1128 		}
1129 #ifdef CONFIG_IPV6_SUBTREES
1130 backtrack:
1131 #endif
1132 		if (fn->fn_flags & RTN_ROOT)
1133 			break;
1134 
1135 		fn = fn->parent;
1136 	}
1137 
1138 	return NULL;
1139 }
1140 
1141 struct fib6_node *fib6_lookup(struct fib6_node *root, const struct in6_addr *daddr,
1142 			      const struct in6_addr *saddr)
1143 {
1144 	struct fib6_node *fn;
1145 	struct lookup_args args[] = {
1146 		{
1147 			.offset = offsetof(struct rt6_info, rt6i_dst),
1148 			.addr = daddr,
1149 		},
1150 #ifdef CONFIG_IPV6_SUBTREES
1151 		{
1152 			.offset = offsetof(struct rt6_info, rt6i_src),
1153 			.addr = saddr,
1154 		},
1155 #endif
1156 		{
1157 			.offset = 0,	/* sentinel */
1158 		}
1159 	};
1160 
1161 	fn = fib6_lookup_1(root, daddr ? args : args + 1);
1162 	if (!fn || fn->fn_flags & RTN_TL_ROOT)
1163 		fn = root;
1164 
1165 	return fn;
1166 }
1167 
1168 /*
1169  *	Get node with specified destination prefix (and source prefix,
1170  *	if subtrees are used)
1171  */
1172 
1173 
1174 static struct fib6_node *fib6_locate_1(struct fib6_node *root,
1175 				       const struct in6_addr *addr,
1176 				       int plen, int offset)
1177 {
1178 	struct fib6_node *fn;
1179 
1180 	for (fn = root; fn ; ) {
1181 		struct rt6key *key = (struct rt6key *)((u8 *)fn->leaf + offset);
1182 
1183 		/*
1184 		 *	Prefix match
1185 		 */
1186 		if (plen < fn->fn_bit ||
1187 		    !ipv6_prefix_equal(&key->addr, addr, fn->fn_bit))
1188 			return NULL;
1189 
1190 		if (plen == fn->fn_bit)
1191 			return fn;
1192 
1193 		/*
1194 		 *	We have more bits to go
1195 		 */
1196 		if (addr_bit_set(addr, fn->fn_bit))
1197 			fn = fn->right;
1198 		else
1199 			fn = fn->left;
1200 	}
1201 	return NULL;
1202 }
1203 
1204 struct fib6_node *fib6_locate(struct fib6_node *root,
1205 			      const struct in6_addr *daddr, int dst_len,
1206 			      const struct in6_addr *saddr, int src_len)
1207 {
1208 	struct fib6_node *fn;
1209 
1210 	fn = fib6_locate_1(root, daddr, dst_len,
1211 			   offsetof(struct rt6_info, rt6i_dst));
1212 
1213 #ifdef CONFIG_IPV6_SUBTREES
1214 	if (src_len) {
1215 		WARN_ON(saddr == NULL);
1216 		if (fn && fn->subtree)
1217 			fn = fib6_locate_1(fn->subtree, saddr, src_len,
1218 					   offsetof(struct rt6_info, rt6i_src));
1219 	}
1220 #endif
1221 
1222 	if (fn && fn->fn_flags & RTN_RTINFO)
1223 		return fn;
1224 
1225 	return NULL;
1226 }
1227 
1228 
1229 /*
1230  *	Deletion
1231  *
1232  */
1233 
1234 static struct rt6_info *fib6_find_prefix(struct net *net, struct fib6_node *fn)
1235 {
1236 	if (fn->fn_flags & RTN_ROOT)
1237 		return net->ipv6.ip6_null_entry;
1238 
1239 	while (fn) {
1240 		if (fn->left)
1241 			return fn->left->leaf;
1242 		if (fn->right)
1243 			return fn->right->leaf;
1244 
1245 		fn = FIB6_SUBTREE(fn);
1246 	}
1247 	return NULL;
1248 }
1249 
1250 /*
1251  *	Called to trim the tree of intermediate nodes when possible. "fn"
1252  *	is the node we want to try and remove.
1253  */
1254 
1255 static struct fib6_node *fib6_repair_tree(struct net *net,
1256 					   struct fib6_node *fn)
1257 {
1258 	int children;
1259 	int nstate;
1260 	struct fib6_node *child, *pn;
1261 	struct fib6_walker *w;
1262 	int iter = 0;
1263 
1264 	for (;;) {
1265 		RT6_TRACE("fixing tree: plen=%d iter=%d\n", fn->fn_bit, iter);
1266 		iter++;
1267 
1268 		WARN_ON(fn->fn_flags & RTN_RTINFO);
1269 		WARN_ON(fn->fn_flags & RTN_TL_ROOT);
1270 		WARN_ON(fn->leaf);
1271 
1272 		children = 0;
1273 		child = NULL;
1274 		if (fn->right)
1275 			child = fn->right, children |= 1;
1276 		if (fn->left)
1277 			child = fn->left, children |= 2;
1278 
1279 		if (children == 3 || FIB6_SUBTREE(fn)
1280 #ifdef CONFIG_IPV6_SUBTREES
1281 		    /* Subtree root (i.e. fn) may have one child */
1282 		    || (children && fn->fn_flags & RTN_ROOT)
1283 #endif
1284 		    ) {
1285 			fn->leaf = fib6_find_prefix(net, fn);
1286 #if RT6_DEBUG >= 2
1287 			if (!fn->leaf) {
1288 				WARN_ON(!fn->leaf);
1289 				fn->leaf = net->ipv6.ip6_null_entry;
1290 			}
1291 #endif
1292 			atomic_inc(&fn->leaf->rt6i_ref);
1293 			return fn->parent;
1294 		}
1295 
1296 		pn = fn->parent;
1297 #ifdef CONFIG_IPV6_SUBTREES
1298 		if (FIB6_SUBTREE(pn) == fn) {
1299 			WARN_ON(!(fn->fn_flags & RTN_ROOT));
1300 			FIB6_SUBTREE(pn) = NULL;
1301 			nstate = FWS_L;
1302 		} else {
1303 			WARN_ON(fn->fn_flags & RTN_ROOT);
1304 #endif
1305 			if (pn->right == fn)
1306 				pn->right = child;
1307 			else if (pn->left == fn)
1308 				pn->left = child;
1309 #if RT6_DEBUG >= 2
1310 			else
1311 				WARN_ON(1);
1312 #endif
1313 			if (child)
1314 				child->parent = pn;
1315 			nstate = FWS_R;
1316 #ifdef CONFIG_IPV6_SUBTREES
1317 		}
1318 #endif
1319 
1320 		read_lock(&fib6_walker_lock);
1321 		FOR_WALKERS(w) {
1322 			if (!child) {
1323 				if (w->root == fn) {
1324 					w->root = w->node = NULL;
1325 					RT6_TRACE("W %p adjusted by delroot 1\n", w);
1326 				} else if (w->node == fn) {
1327 					RT6_TRACE("W %p adjusted by delnode 1, s=%d/%d\n", w, w->state, nstate);
1328 					w->node = pn;
1329 					w->state = nstate;
1330 				}
1331 			} else {
1332 				if (w->root == fn) {
1333 					w->root = child;
1334 					RT6_TRACE("W %p adjusted by delroot 2\n", w);
1335 				}
1336 				if (w->node == fn) {
1337 					w->node = child;
1338 					if (children&2) {
1339 						RT6_TRACE("W %p adjusted by delnode 2, s=%d\n", w, w->state);
1340 						w->state = w->state >= FWS_R ? FWS_U : FWS_INIT;
1341 					} else {
1342 						RT6_TRACE("W %p adjusted by delnode 2, s=%d\n", w, w->state);
1343 						w->state = w->state >= FWS_C ? FWS_U : FWS_INIT;
1344 					}
1345 				}
1346 			}
1347 		}
1348 		read_unlock(&fib6_walker_lock);
1349 
1350 		node_free(fn);
1351 		if (pn->fn_flags & RTN_RTINFO || FIB6_SUBTREE(pn))
1352 			return pn;
1353 
1354 		rt6_release(pn->leaf);
1355 		pn->leaf = NULL;
1356 		fn = pn;
1357 	}
1358 }
1359 
1360 static void fib6_del_route(struct fib6_node *fn, struct rt6_info **rtp,
1361 			   struct nl_info *info)
1362 {
1363 	struct fib6_walker *w;
1364 	struct rt6_info *rt = *rtp;
1365 	struct net *net = info->nl_net;
1366 
1367 	RT6_TRACE("fib6_del_route\n");
1368 
1369 	/* Unlink it */
1370 	*rtp = rt->dst.rt6_next;
1371 	rt->rt6i_node = NULL;
1372 	net->ipv6.rt6_stats->fib_rt_entries--;
1373 	net->ipv6.rt6_stats->fib_discarded_routes++;
1374 
1375 	/* Reset round-robin state, if necessary */
1376 	if (fn->rr_ptr == rt)
1377 		fn->rr_ptr = NULL;
1378 
1379 	/* Remove this entry from other siblings */
1380 	if (rt->rt6i_nsiblings) {
1381 		struct rt6_info *sibling, *next_sibling;
1382 
1383 		list_for_each_entry_safe(sibling, next_sibling,
1384 					 &rt->rt6i_siblings, rt6i_siblings)
1385 			sibling->rt6i_nsiblings--;
1386 		rt->rt6i_nsiblings = 0;
1387 		list_del_init(&rt->rt6i_siblings);
1388 	}
1389 
1390 	/* Adjust walkers */
1391 	read_lock(&fib6_walker_lock);
1392 	FOR_WALKERS(w) {
1393 		if (w->state == FWS_C && w->leaf == rt) {
1394 			RT6_TRACE("walker %p adjusted by delroute\n", w);
1395 			w->leaf = rt->dst.rt6_next;
1396 			if (!w->leaf)
1397 				w->state = FWS_U;
1398 		}
1399 	}
1400 	read_unlock(&fib6_walker_lock);
1401 
1402 	rt->dst.rt6_next = NULL;
1403 
1404 	/* If it was last route, expunge its radix tree node */
1405 	if (!fn->leaf) {
1406 		fn->fn_flags &= ~RTN_RTINFO;
1407 		net->ipv6.rt6_stats->fib_route_nodes--;
1408 		fn = fib6_repair_tree(net, fn);
1409 	}
1410 
1411 	fib6_purge_rt(rt, fn, net);
1412 
1413 	inet6_rt_notify(RTM_DELROUTE, rt, info);
1414 	rt6_release(rt);
1415 }
1416 
1417 int fib6_del(struct rt6_info *rt, struct nl_info *info)
1418 {
1419 	struct net *net = info->nl_net;
1420 	struct fib6_node *fn = rt->rt6i_node;
1421 	struct rt6_info **rtp;
1422 
1423 #if RT6_DEBUG >= 2
1424 	if (rt->dst.obsolete > 0) {
1425 		WARN_ON(fn);
1426 		return -ENOENT;
1427 	}
1428 #endif
1429 	if (!fn || rt == net->ipv6.ip6_null_entry)
1430 		return -ENOENT;
1431 
1432 	WARN_ON(!(fn->fn_flags & RTN_RTINFO));
1433 
1434 	if (!(rt->rt6i_flags & RTF_CACHE)) {
1435 		struct fib6_node *pn = fn;
1436 #ifdef CONFIG_IPV6_SUBTREES
1437 		/* clones of this route might be in another subtree */
1438 		if (rt->rt6i_src.plen) {
1439 			while (!(pn->fn_flags & RTN_ROOT))
1440 				pn = pn->parent;
1441 			pn = pn->parent;
1442 		}
1443 #endif
1444 		fib6_prune_clones(info->nl_net, pn);
1445 	}
1446 
1447 	/*
1448 	 *	Walk the leaf entries looking for ourself
1449 	 */
1450 
1451 	for (rtp = &fn->leaf; *rtp; rtp = &(*rtp)->dst.rt6_next) {
1452 		if (*rtp == rt) {
1453 			fib6_del_route(fn, rtp, info);
1454 			return 0;
1455 		}
1456 	}
1457 	return -ENOENT;
1458 }
1459 
1460 /*
1461  *	Tree traversal function.
1462  *
1463  *	Certainly, it is not interrupt safe.
1464  *	However, it is internally reenterable wrt itself and fib6_add/fib6_del.
1465  *	It means, that we can modify tree during walking
1466  *	and use this function for garbage collection, clone pruning,
1467  *	cleaning tree when a device goes down etc. etc.
1468  *
1469  *	It guarantees that every node will be traversed,
1470  *	and that it will be traversed only once.
1471  *
1472  *	Callback function w->func may return:
1473  *	0 -> continue walking.
1474  *	positive value -> walking is suspended (used by tree dumps,
1475  *	and probably by gc, if it will be split to several slices)
1476  *	negative value -> terminate walking.
1477  *
1478  *	The function itself returns:
1479  *	0   -> walk is complete.
1480  *	>0  -> walk is incomplete (i.e. suspended)
1481  *	<0  -> walk is terminated by an error.
1482  */
1483 
1484 static int fib6_walk_continue(struct fib6_walker *w)
1485 {
1486 	struct fib6_node *fn, *pn;
1487 
1488 	for (;;) {
1489 		fn = w->node;
1490 		if (!fn)
1491 			return 0;
1492 
1493 		if (w->prune && fn != w->root &&
1494 		    fn->fn_flags & RTN_RTINFO && w->state < FWS_C) {
1495 			w->state = FWS_C;
1496 			w->leaf = fn->leaf;
1497 		}
1498 		switch (w->state) {
1499 #ifdef CONFIG_IPV6_SUBTREES
1500 		case FWS_S:
1501 			if (FIB6_SUBTREE(fn)) {
1502 				w->node = FIB6_SUBTREE(fn);
1503 				continue;
1504 			}
1505 			w->state = FWS_L;
1506 #endif
1507 		case FWS_L:
1508 			if (fn->left) {
1509 				w->node = fn->left;
1510 				w->state = FWS_INIT;
1511 				continue;
1512 			}
1513 			w->state = FWS_R;
1514 		case FWS_R:
1515 			if (fn->right) {
1516 				w->node = fn->right;
1517 				w->state = FWS_INIT;
1518 				continue;
1519 			}
1520 			w->state = FWS_C;
1521 			w->leaf = fn->leaf;
1522 		case FWS_C:
1523 			if (w->leaf && fn->fn_flags & RTN_RTINFO) {
1524 				int err;
1525 
1526 				if (w->skip) {
1527 					w->skip--;
1528 					goto skip;
1529 				}
1530 
1531 				err = w->func(w);
1532 				if (err)
1533 					return err;
1534 
1535 				w->count++;
1536 				continue;
1537 			}
1538 skip:
1539 			w->state = FWS_U;
1540 		case FWS_U:
1541 			if (fn == w->root)
1542 				return 0;
1543 			pn = fn->parent;
1544 			w->node = pn;
1545 #ifdef CONFIG_IPV6_SUBTREES
1546 			if (FIB6_SUBTREE(pn) == fn) {
1547 				WARN_ON(!(fn->fn_flags & RTN_ROOT));
1548 				w->state = FWS_L;
1549 				continue;
1550 			}
1551 #endif
1552 			if (pn->left == fn) {
1553 				w->state = FWS_R;
1554 				continue;
1555 			}
1556 			if (pn->right == fn) {
1557 				w->state = FWS_C;
1558 				w->leaf = w->node->leaf;
1559 				continue;
1560 			}
1561 #if RT6_DEBUG >= 2
1562 			WARN_ON(1);
1563 #endif
1564 		}
1565 	}
1566 }
1567 
1568 static int fib6_walk(struct fib6_walker *w)
1569 {
1570 	int res;
1571 
1572 	w->state = FWS_INIT;
1573 	w->node = w->root;
1574 
1575 	fib6_walker_link(w);
1576 	res = fib6_walk_continue(w);
1577 	if (res <= 0)
1578 		fib6_walker_unlink(w);
1579 	return res;
1580 }
1581 
1582 static int fib6_clean_node(struct fib6_walker *w)
1583 {
1584 	int res;
1585 	struct rt6_info *rt;
1586 	struct fib6_cleaner *c = container_of(w, struct fib6_cleaner, w);
1587 	struct nl_info info = {
1588 		.nl_net = c->net,
1589 	};
1590 
1591 	if (c->sernum != FIB6_NO_SERNUM_CHANGE &&
1592 	    w->node->fn_sernum != c->sernum)
1593 		w->node->fn_sernum = c->sernum;
1594 
1595 	if (!c->func) {
1596 		WARN_ON_ONCE(c->sernum == FIB6_NO_SERNUM_CHANGE);
1597 		w->leaf = NULL;
1598 		return 0;
1599 	}
1600 
1601 	for (rt = w->leaf; rt; rt = rt->dst.rt6_next) {
1602 		res = c->func(rt, c->arg);
1603 		if (res < 0) {
1604 			w->leaf = rt;
1605 			res = fib6_del(rt, &info);
1606 			if (res) {
1607 #if RT6_DEBUG >= 2
1608 				pr_debug("%s: del failed: rt=%p@%p err=%d\n",
1609 					 __func__, rt, rt->rt6i_node, res);
1610 #endif
1611 				continue;
1612 			}
1613 			return 0;
1614 		}
1615 		WARN_ON(res != 0);
1616 	}
1617 	w->leaf = rt;
1618 	return 0;
1619 }
1620 
1621 /*
1622  *	Convenient frontend to tree walker.
1623  *
1624  *	func is called on each route.
1625  *		It may return -1 -> delete this route.
1626  *		              0  -> continue walking
1627  *
1628  *	prune==1 -> only immediate children of node (certainly,
1629  *	ignoring pure split nodes) will be scanned.
1630  */
1631 
1632 static void fib6_clean_tree(struct net *net, struct fib6_node *root,
1633 			    int (*func)(struct rt6_info *, void *arg),
1634 			    bool prune, int sernum, void *arg)
1635 {
1636 	struct fib6_cleaner c;
1637 
1638 	c.w.root = root;
1639 	c.w.func = fib6_clean_node;
1640 	c.w.prune = prune;
1641 	c.w.count = 0;
1642 	c.w.skip = 0;
1643 	c.func = func;
1644 	c.sernum = sernum;
1645 	c.arg = arg;
1646 	c.net = net;
1647 
1648 	fib6_walk(&c.w);
1649 }
1650 
1651 static void __fib6_clean_all(struct net *net,
1652 			     int (*func)(struct rt6_info *, void *),
1653 			     int sernum, void *arg)
1654 {
1655 	struct fib6_table *table;
1656 	struct hlist_head *head;
1657 	unsigned int h;
1658 
1659 	rcu_read_lock();
1660 	for (h = 0; h < FIB6_TABLE_HASHSZ; h++) {
1661 		head = &net->ipv6.fib_table_hash[h];
1662 		hlist_for_each_entry_rcu(table, head, tb6_hlist) {
1663 			write_lock_bh(&table->tb6_lock);
1664 			fib6_clean_tree(net, &table->tb6_root,
1665 					func, false, sernum, arg);
1666 			write_unlock_bh(&table->tb6_lock);
1667 		}
1668 	}
1669 	rcu_read_unlock();
1670 }
1671 
1672 void fib6_clean_all(struct net *net, int (*func)(struct rt6_info *, void *),
1673 		    void *arg)
1674 {
1675 	__fib6_clean_all(net, func, FIB6_NO_SERNUM_CHANGE, arg);
1676 }
1677 
1678 static int fib6_prune_clone(struct rt6_info *rt, void *arg)
1679 {
1680 	if (rt->rt6i_flags & RTF_CACHE) {
1681 		RT6_TRACE("pruning clone %p\n", rt);
1682 		return -1;
1683 	}
1684 
1685 	return 0;
1686 }
1687 
1688 static void fib6_prune_clones(struct net *net, struct fib6_node *fn)
1689 {
1690 	fib6_clean_tree(net, fn, fib6_prune_clone, true,
1691 			FIB6_NO_SERNUM_CHANGE, NULL);
1692 }
1693 
1694 static void fib6_flush_trees(struct net *net)
1695 {
1696 	int new_sernum = fib6_new_sernum(net);
1697 
1698 	__fib6_clean_all(net, NULL, new_sernum, NULL);
1699 }
1700 
1701 /*
1702  *	Garbage collection
1703  */
1704 
1705 static struct fib6_gc_args
1706 {
1707 	int			timeout;
1708 	int			more;
1709 } gc_args;
1710 
1711 static int fib6_age(struct rt6_info *rt, void *arg)
1712 {
1713 	unsigned long now = jiffies;
1714 
1715 	/*
1716 	 *	check addrconf expiration here.
1717 	 *	Routes are expired even if they are in use.
1718 	 *
1719 	 *	Also age clones. Note, that clones are aged out
1720 	 *	only if they are not in use now.
1721 	 */
1722 
1723 	if (rt->rt6i_flags & RTF_EXPIRES && rt->dst.expires) {
1724 		if (time_after(now, rt->dst.expires)) {
1725 			RT6_TRACE("expiring %p\n", rt);
1726 			return -1;
1727 		}
1728 		gc_args.more++;
1729 	} else if (rt->rt6i_flags & RTF_CACHE) {
1730 		if (atomic_read(&rt->dst.__refcnt) == 0 &&
1731 		    time_after_eq(now, rt->dst.lastuse + gc_args.timeout)) {
1732 			RT6_TRACE("aging clone %p\n", rt);
1733 			return -1;
1734 		} else if (rt->rt6i_flags & RTF_GATEWAY) {
1735 			struct neighbour *neigh;
1736 			__u8 neigh_flags = 0;
1737 
1738 			neigh = dst_neigh_lookup(&rt->dst, &rt->rt6i_gateway);
1739 			if (neigh) {
1740 				neigh_flags = neigh->flags;
1741 				neigh_release(neigh);
1742 			}
1743 			if (!(neigh_flags & NTF_ROUTER)) {
1744 				RT6_TRACE("purging route %p via non-router but gateway\n",
1745 					  rt);
1746 				return -1;
1747 			}
1748 		}
1749 		gc_args.more++;
1750 	}
1751 
1752 	return 0;
1753 }
1754 
1755 static DEFINE_SPINLOCK(fib6_gc_lock);
1756 
1757 void fib6_run_gc(unsigned long expires, struct net *net, bool force)
1758 {
1759 	unsigned long now;
1760 
1761 	if (force) {
1762 		spin_lock_bh(&fib6_gc_lock);
1763 	} else if (!spin_trylock_bh(&fib6_gc_lock)) {
1764 		mod_timer(&net->ipv6.ip6_fib_timer, jiffies + HZ);
1765 		return;
1766 	}
1767 	gc_args.timeout = expires ? (int)expires :
1768 			  net->ipv6.sysctl.ip6_rt_gc_interval;
1769 
1770 	gc_args.more = icmp6_dst_gc();
1771 
1772 	fib6_clean_all(net, fib6_age, NULL);
1773 	now = jiffies;
1774 	net->ipv6.ip6_rt_last_gc = now;
1775 
1776 	if (gc_args.more)
1777 		mod_timer(&net->ipv6.ip6_fib_timer,
1778 			  round_jiffies(now
1779 					+ net->ipv6.sysctl.ip6_rt_gc_interval));
1780 	else
1781 		del_timer(&net->ipv6.ip6_fib_timer);
1782 	spin_unlock_bh(&fib6_gc_lock);
1783 }
1784 
1785 static void fib6_gc_timer_cb(unsigned long arg)
1786 {
1787 	fib6_run_gc(0, (struct net *)arg, true);
1788 }
1789 
1790 static int __net_init fib6_net_init(struct net *net)
1791 {
1792 	size_t size = sizeof(struct hlist_head) * FIB6_TABLE_HASHSZ;
1793 
1794 	setup_timer(&net->ipv6.ip6_fib_timer, fib6_gc_timer_cb, (unsigned long)net);
1795 
1796 	net->ipv6.rt6_stats = kzalloc(sizeof(*net->ipv6.rt6_stats), GFP_KERNEL);
1797 	if (!net->ipv6.rt6_stats)
1798 		goto out_timer;
1799 
1800 	/* Avoid false sharing : Use at least a full cache line */
1801 	size = max_t(size_t, size, L1_CACHE_BYTES);
1802 
1803 	net->ipv6.fib_table_hash = kzalloc(size, GFP_KERNEL);
1804 	if (!net->ipv6.fib_table_hash)
1805 		goto out_rt6_stats;
1806 
1807 	net->ipv6.fib6_main_tbl = kzalloc(sizeof(*net->ipv6.fib6_main_tbl),
1808 					  GFP_KERNEL);
1809 	if (!net->ipv6.fib6_main_tbl)
1810 		goto out_fib_table_hash;
1811 
1812 	net->ipv6.fib6_main_tbl->tb6_id = RT6_TABLE_MAIN;
1813 	net->ipv6.fib6_main_tbl->tb6_root.leaf = net->ipv6.ip6_null_entry;
1814 	net->ipv6.fib6_main_tbl->tb6_root.fn_flags =
1815 		RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
1816 	inet_peer_base_init(&net->ipv6.fib6_main_tbl->tb6_peers);
1817 
1818 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
1819 	net->ipv6.fib6_local_tbl = kzalloc(sizeof(*net->ipv6.fib6_local_tbl),
1820 					   GFP_KERNEL);
1821 	if (!net->ipv6.fib6_local_tbl)
1822 		goto out_fib6_main_tbl;
1823 	net->ipv6.fib6_local_tbl->tb6_id = RT6_TABLE_LOCAL;
1824 	net->ipv6.fib6_local_tbl->tb6_root.leaf = net->ipv6.ip6_null_entry;
1825 	net->ipv6.fib6_local_tbl->tb6_root.fn_flags =
1826 		RTN_ROOT | RTN_TL_ROOT | RTN_RTINFO;
1827 	inet_peer_base_init(&net->ipv6.fib6_local_tbl->tb6_peers);
1828 #endif
1829 	fib6_tables_init(net);
1830 
1831 	return 0;
1832 
1833 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
1834 out_fib6_main_tbl:
1835 	kfree(net->ipv6.fib6_main_tbl);
1836 #endif
1837 out_fib_table_hash:
1838 	kfree(net->ipv6.fib_table_hash);
1839 out_rt6_stats:
1840 	kfree(net->ipv6.rt6_stats);
1841 out_timer:
1842 	return -ENOMEM;
1843 }
1844 
1845 static void fib6_net_exit(struct net *net)
1846 {
1847 	rt6_ifdown(net, NULL);
1848 	del_timer_sync(&net->ipv6.ip6_fib_timer);
1849 
1850 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
1851 	inetpeer_invalidate_tree(&net->ipv6.fib6_local_tbl->tb6_peers);
1852 	kfree(net->ipv6.fib6_local_tbl);
1853 #endif
1854 	inetpeer_invalidate_tree(&net->ipv6.fib6_main_tbl->tb6_peers);
1855 	kfree(net->ipv6.fib6_main_tbl);
1856 	kfree(net->ipv6.fib_table_hash);
1857 	kfree(net->ipv6.rt6_stats);
1858 }
1859 
1860 static struct pernet_operations fib6_net_ops = {
1861 	.init = fib6_net_init,
1862 	.exit = fib6_net_exit,
1863 };
1864 
1865 int __init fib6_init(void)
1866 {
1867 	int ret = -ENOMEM;
1868 
1869 	fib6_node_kmem = kmem_cache_create("fib6_nodes",
1870 					   sizeof(struct fib6_node),
1871 					   0, SLAB_HWCACHE_ALIGN,
1872 					   NULL);
1873 	if (!fib6_node_kmem)
1874 		goto out;
1875 
1876 	ret = register_pernet_subsys(&fib6_net_ops);
1877 	if (ret)
1878 		goto out_kmem_cache_create;
1879 
1880 	ret = __rtnl_register(PF_INET6, RTM_GETROUTE, NULL, inet6_dump_fib,
1881 			      NULL);
1882 	if (ret)
1883 		goto out_unregister_subsys;
1884 
1885 	__fib6_flush_trees = fib6_flush_trees;
1886 out:
1887 	return ret;
1888 
1889 out_unregister_subsys:
1890 	unregister_pernet_subsys(&fib6_net_ops);
1891 out_kmem_cache_create:
1892 	kmem_cache_destroy(fib6_node_kmem);
1893 	goto out;
1894 }
1895 
1896 void fib6_gc_cleanup(void)
1897 {
1898 	unregister_pernet_subsys(&fib6_net_ops);
1899 	kmem_cache_destroy(fib6_node_kmem);
1900 }
1901 
1902 #ifdef CONFIG_PROC_FS
1903 
1904 struct ipv6_route_iter {
1905 	struct seq_net_private p;
1906 	struct fib6_walker w;
1907 	loff_t skip;
1908 	struct fib6_table *tbl;
1909 	int sernum;
1910 };
1911 
1912 static int ipv6_route_seq_show(struct seq_file *seq, void *v)
1913 {
1914 	struct rt6_info *rt = v;
1915 	struct ipv6_route_iter *iter = seq->private;
1916 
1917 	seq_printf(seq, "%pi6 %02x ", &rt->rt6i_dst.addr, rt->rt6i_dst.plen);
1918 
1919 #ifdef CONFIG_IPV6_SUBTREES
1920 	seq_printf(seq, "%pi6 %02x ", &rt->rt6i_src.addr, rt->rt6i_src.plen);
1921 #else
1922 	seq_puts(seq, "00000000000000000000000000000000 00 ");
1923 #endif
1924 	if (rt->rt6i_flags & RTF_GATEWAY)
1925 		seq_printf(seq, "%pi6", &rt->rt6i_gateway);
1926 	else
1927 		seq_puts(seq, "00000000000000000000000000000000");
1928 
1929 	seq_printf(seq, " %08x %08x %08x %08x %8s\n",
1930 		   rt->rt6i_metric, atomic_read(&rt->dst.__refcnt),
1931 		   rt->dst.__use, rt->rt6i_flags,
1932 		   rt->dst.dev ? rt->dst.dev->name : "");
1933 	iter->w.leaf = NULL;
1934 	return 0;
1935 }
1936 
1937 static int ipv6_route_yield(struct fib6_walker *w)
1938 {
1939 	struct ipv6_route_iter *iter = w->args;
1940 
1941 	if (!iter->skip)
1942 		return 1;
1943 
1944 	do {
1945 		iter->w.leaf = iter->w.leaf->dst.rt6_next;
1946 		iter->skip--;
1947 		if (!iter->skip && iter->w.leaf)
1948 			return 1;
1949 	} while (iter->w.leaf);
1950 
1951 	return 0;
1952 }
1953 
1954 static void ipv6_route_seq_setup_walk(struct ipv6_route_iter *iter)
1955 {
1956 	memset(&iter->w, 0, sizeof(iter->w));
1957 	iter->w.func = ipv6_route_yield;
1958 	iter->w.root = &iter->tbl->tb6_root;
1959 	iter->w.state = FWS_INIT;
1960 	iter->w.node = iter->w.root;
1961 	iter->w.args = iter;
1962 	iter->sernum = iter->w.root->fn_sernum;
1963 	INIT_LIST_HEAD(&iter->w.lh);
1964 	fib6_walker_link(&iter->w);
1965 }
1966 
1967 static struct fib6_table *ipv6_route_seq_next_table(struct fib6_table *tbl,
1968 						    struct net *net)
1969 {
1970 	unsigned int h;
1971 	struct hlist_node *node;
1972 
1973 	if (tbl) {
1974 		h = (tbl->tb6_id & (FIB6_TABLE_HASHSZ - 1)) + 1;
1975 		node = rcu_dereference_bh(hlist_next_rcu(&tbl->tb6_hlist));
1976 	} else {
1977 		h = 0;
1978 		node = NULL;
1979 	}
1980 
1981 	while (!node && h < FIB6_TABLE_HASHSZ) {
1982 		node = rcu_dereference_bh(
1983 			hlist_first_rcu(&net->ipv6.fib_table_hash[h++]));
1984 	}
1985 	return hlist_entry_safe(node, struct fib6_table, tb6_hlist);
1986 }
1987 
1988 static void ipv6_route_check_sernum(struct ipv6_route_iter *iter)
1989 {
1990 	if (iter->sernum != iter->w.root->fn_sernum) {
1991 		iter->sernum = iter->w.root->fn_sernum;
1992 		iter->w.state = FWS_INIT;
1993 		iter->w.node = iter->w.root;
1994 		WARN_ON(iter->w.skip);
1995 		iter->w.skip = iter->w.count;
1996 	}
1997 }
1998 
1999 static void *ipv6_route_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2000 {
2001 	int r;
2002 	struct rt6_info *n;
2003 	struct net *net = seq_file_net(seq);
2004 	struct ipv6_route_iter *iter = seq->private;
2005 
2006 	if (!v)
2007 		goto iter_table;
2008 
2009 	n = ((struct rt6_info *)v)->dst.rt6_next;
2010 	if (n) {
2011 		++*pos;
2012 		return n;
2013 	}
2014 
2015 iter_table:
2016 	ipv6_route_check_sernum(iter);
2017 	read_lock(&iter->tbl->tb6_lock);
2018 	r = fib6_walk_continue(&iter->w);
2019 	read_unlock(&iter->tbl->tb6_lock);
2020 	if (r > 0) {
2021 		if (v)
2022 			++*pos;
2023 		return iter->w.leaf;
2024 	} else if (r < 0) {
2025 		fib6_walker_unlink(&iter->w);
2026 		return NULL;
2027 	}
2028 	fib6_walker_unlink(&iter->w);
2029 
2030 	iter->tbl = ipv6_route_seq_next_table(iter->tbl, net);
2031 	if (!iter->tbl)
2032 		return NULL;
2033 
2034 	ipv6_route_seq_setup_walk(iter);
2035 	goto iter_table;
2036 }
2037 
2038 static void *ipv6_route_seq_start(struct seq_file *seq, loff_t *pos)
2039 	__acquires(RCU_BH)
2040 {
2041 	struct net *net = seq_file_net(seq);
2042 	struct ipv6_route_iter *iter = seq->private;
2043 
2044 	rcu_read_lock_bh();
2045 	iter->tbl = ipv6_route_seq_next_table(NULL, net);
2046 	iter->skip = *pos;
2047 
2048 	if (iter->tbl) {
2049 		ipv6_route_seq_setup_walk(iter);
2050 		return ipv6_route_seq_next(seq, NULL, pos);
2051 	} else {
2052 		return NULL;
2053 	}
2054 }
2055 
2056 static bool ipv6_route_iter_active(struct ipv6_route_iter *iter)
2057 {
2058 	struct fib6_walker *w = &iter->w;
2059 	return w->node && !(w->state == FWS_U && w->node == w->root);
2060 }
2061 
2062 static void ipv6_route_seq_stop(struct seq_file *seq, void *v)
2063 	__releases(RCU_BH)
2064 {
2065 	struct ipv6_route_iter *iter = seq->private;
2066 
2067 	if (ipv6_route_iter_active(iter))
2068 		fib6_walker_unlink(&iter->w);
2069 
2070 	rcu_read_unlock_bh();
2071 }
2072 
2073 static const struct seq_operations ipv6_route_seq_ops = {
2074 	.start	= ipv6_route_seq_start,
2075 	.next	= ipv6_route_seq_next,
2076 	.stop	= ipv6_route_seq_stop,
2077 	.show	= ipv6_route_seq_show
2078 };
2079 
2080 int ipv6_route_open(struct inode *inode, struct file *file)
2081 {
2082 	return seq_open_net(inode, file, &ipv6_route_seq_ops,
2083 			    sizeof(struct ipv6_route_iter));
2084 }
2085 
2086 #endif /* CONFIG_PROC_FS */
2087