br_fdb.c revision f64f9e719261a87818dd192a3a2352e5b20fbd0f 
1/*
2 *	Forwarding database
3 *	Linux ethernet bridge
4 *
5 *	Authors:
6 *	Lennert Buytenhek		<buytenh@gnu.org>
7 *
8 *	This program is free software; you can redistribute it and/or
9 *	modify it under the terms of the GNU General Public License
10 *	as published by the Free Software Foundation; either version
11 *	2 of the License, or (at your option) any later version.
12 */
13
14#include <linux/kernel.h>
15#include <linux/init.h>
16#include <linux/rculist.h>
17#include <linux/spinlock.h>
18#include <linux/times.h>
19#include <linux/netdevice.h>
20#include <linux/etherdevice.h>
21#include <linux/jhash.h>
22#include <linux/random.h>
23#include <asm/atomic.h>
24#include <asm/unaligned.h>
25#include "br_private.h"
26
27static struct kmem_cache *br_fdb_cache __read_mostly;
28static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
29		      const unsigned char *addr);
30
31static u32 fdb_salt __read_mostly;
32
33int __init br_fdb_init(void)
34{
35	br_fdb_cache = kmem_cache_create("bridge_fdb_cache",
36					 sizeof(struct net_bridge_fdb_entry),
37					 0,
38					 SLAB_HWCACHE_ALIGN, NULL);
39	if (!br_fdb_cache)
40		return -ENOMEM;
41
42	get_random_bytes(&fdb_salt, sizeof(fdb_salt));
43	return 0;
44}
45
46void br_fdb_fini(void)
47{
48	kmem_cache_destroy(br_fdb_cache);
49}
50
51
52/* if topology_changing then use forward_delay (default 15 sec)
53 * otherwise keep longer (default 5 minutes)
54 */
55static inline unsigned long hold_time(const struct net_bridge *br)
56{
57	return br->topology_change ? br->forward_delay : br->ageing_time;
58}
59
60static inline int has_expired(const struct net_bridge *br,
61				  const struct net_bridge_fdb_entry *fdb)
62{
63	return !fdb->is_static &&
64		time_before_eq(fdb->ageing_timer + hold_time(br), jiffies);
65}
66
67static inline int br_mac_hash(const unsigned char *mac)
68{
69	/* use 1 byte of OUI cnd 3 bytes of NIC */
70	u32 key = get_unaligned((u32 *)(mac + 2));
71	return jhash_1word(key, fdb_salt) & (BR_HASH_SIZE - 1);
72}
73
74static void fdb_rcu_free(struct rcu_head *head)
75{
76	struct net_bridge_fdb_entry *ent
77		= container_of(head, struct net_bridge_fdb_entry, rcu);
78	kmem_cache_free(br_fdb_cache, ent);
79}
80
81static inline void fdb_delete(struct net_bridge_fdb_entry *f)
82{
83	hlist_del_rcu(&f->hlist);
84	call_rcu(&f->rcu, fdb_rcu_free);
85}
86
87void br_fdb_changeaddr(struct net_bridge_port *p, const unsigned char *newaddr)
88{
89	struct net_bridge *br = p->br;
90	int i;
91
92	spin_lock_bh(&br->hash_lock);
93
94	/* Search all chains since old address/hash is unknown */
95	for (i = 0; i < BR_HASH_SIZE; i++) {
96		struct hlist_node *h;
97		hlist_for_each(h, &br->hash[i]) {
98			struct net_bridge_fdb_entry *f;
99
100			f = hlist_entry(h, struct net_bridge_fdb_entry, hlist);
101			if (f->dst == p && f->is_local) {
102				/* maybe another port has same hw addr? */
103				struct net_bridge_port *op;
104				list_for_each_entry(op, &br->port_list, list) {
105					if (op != p &&
106					    !compare_ether_addr(op->dev->dev_addr,
107								f->addr.addr)) {
108						f->dst = op;
109						goto insert;
110					}
111				}
112
113				/* delete old one */
114				fdb_delete(f);
115				goto insert;
116			}
117		}
118	}
119 insert:
120	/* insert new address,  may fail if invalid address or dup. */
121	fdb_insert(br, p, newaddr);
122
123	spin_unlock_bh(&br->hash_lock);
124}
125
126void br_fdb_cleanup(unsigned long _data)
127{
128	struct net_bridge *br = (struct net_bridge *)_data;
129	unsigned long delay = hold_time(br);
130	unsigned long next_timer = jiffies + br->forward_delay;
131	int i;
132
133	spin_lock_bh(&br->hash_lock);
134	for (i = 0; i < BR_HASH_SIZE; i++) {
135		struct net_bridge_fdb_entry *f;
136		struct hlist_node *h, *n;
137
138		hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
139			unsigned long this_timer;
140			if (f->is_static)
141				continue;
142			this_timer = f->ageing_timer + delay;
143			if (time_before_eq(this_timer, jiffies))
144				fdb_delete(f);
145			else if (time_before(this_timer, next_timer))
146				next_timer = this_timer;
147		}
148	}
149	spin_unlock_bh(&br->hash_lock);
150
151	/* Add HZ/4 to ensure we round the jiffies upwards to be after the next
152	 * timer, otherwise we might round down and will have no-op run. */
153	mod_timer(&br->gc_timer, round_jiffies(next_timer + HZ/4));
154}
155
156/* Completely flush all dynamic entries in forwarding database.*/
157void br_fdb_flush(struct net_bridge *br)
158{
159	int i;
160
161	spin_lock_bh(&br->hash_lock);
162	for (i = 0; i < BR_HASH_SIZE; i++) {
163		struct net_bridge_fdb_entry *f;
164		struct hlist_node *h, *n;
165		hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
166			if (!f->is_static)
167				fdb_delete(f);
168		}
169	}
170	spin_unlock_bh(&br->hash_lock);
171}
172
173/* Flush all entries refering to a specific port.
174 * if do_all is set also flush static entries
175 */
176void br_fdb_delete_by_port(struct net_bridge *br,
177			   const struct net_bridge_port *p,
178			   int do_all)
179{
180	int i;
181
182	spin_lock_bh(&br->hash_lock);
183	for (i = 0; i < BR_HASH_SIZE; i++) {
184		struct hlist_node *h, *g;
185
186		hlist_for_each_safe(h, g, &br->hash[i]) {
187			struct net_bridge_fdb_entry *f
188				= hlist_entry(h, struct net_bridge_fdb_entry, hlist);
189			if (f->dst != p)
190				continue;
191
192			if (f->is_static && !do_all)
193				continue;
194			/*
195			 * if multiple ports all have the same device address
196			 * then when one port is deleted, assign
197			 * the local entry to other port
198			 */
199			if (f->is_local) {
200				struct net_bridge_port *op;
201				list_for_each_entry(op, &br->port_list, list) {
202					if (op != p &&
203					    !compare_ether_addr(op->dev->dev_addr,
204								f->addr.addr)) {
205						f->dst = op;
206						goto skip_delete;
207					}
208				}
209			}
210
211			fdb_delete(f);
212		skip_delete: ;
213		}
214	}
215	spin_unlock_bh(&br->hash_lock);
216}
217
218/* No locking or refcounting, assumes caller has no preempt (rcu_read_lock) */
219struct net_bridge_fdb_entry *__br_fdb_get(struct net_bridge *br,
220					  const unsigned char *addr)
221{
222	struct hlist_node *h;
223	struct net_bridge_fdb_entry *fdb;
224
225	hlist_for_each_entry_rcu(fdb, h, &br->hash[br_mac_hash(addr)], hlist) {
226		if (!compare_ether_addr(fdb->addr.addr, addr)) {
227			if (unlikely(has_expired(br, fdb)))
228				break;
229			return fdb;
230		}
231	}
232
233	return NULL;
234}
235
236#if defined(CONFIG_ATM_LANE) || defined(CONFIG_ATM_LANE_MODULE)
237/* Interface used by ATM LANE hook to test
238 * if an addr is on some other bridge port */
239int br_fdb_test_addr(struct net_device *dev, unsigned char *addr)
240{
241	struct net_bridge_fdb_entry *fdb;
242	int ret;
243
244	if (!dev->br_port)
245		return 0;
246
247	rcu_read_lock();
248	fdb = __br_fdb_get(dev->br_port->br, addr);
249	ret = fdb && fdb->dst->dev != dev &&
250		fdb->dst->state == BR_STATE_FORWARDING;
251	rcu_read_unlock();
252
253	return ret;
254}
255#endif /* CONFIG_ATM_LANE */
256
257/*
258 * Fill buffer with forwarding table records in
259 * the API format.
260 */
261int br_fdb_fillbuf(struct net_bridge *br, void *buf,
262		   unsigned long maxnum, unsigned long skip)
263{
264	struct __fdb_entry *fe = buf;
265	int i, num = 0;
266	struct hlist_node *h;
267	struct net_bridge_fdb_entry *f;
268
269	memset(buf, 0, maxnum*sizeof(struct __fdb_entry));
270
271	rcu_read_lock();
272	for (i = 0; i < BR_HASH_SIZE; i++) {
273		hlist_for_each_entry_rcu(f, h, &br->hash[i], hlist) {
274			if (num >= maxnum)
275				goto out;
276
277			if (has_expired(br, f))
278				continue;
279
280			if (skip) {
281				--skip;
282				continue;
283			}
284
285			/* convert from internal format to API */
286			memcpy(fe->mac_addr, f->addr.addr, ETH_ALEN);
287
288			/* due to ABI compat need to split into hi/lo */
289			fe->port_no = f->dst->port_no;
290			fe->port_hi = f->dst->port_no >> 8;
291
292			fe->is_local = f->is_local;
293			if (!f->is_static)
294				fe->ageing_timer_value = jiffies_to_clock_t(jiffies - f->ageing_timer);
295			++fe;
296			++num;
297		}
298	}
299
300 out:
301	rcu_read_unlock();
302
303	return num;
304}
305
306static inline struct net_bridge_fdb_entry *fdb_find(struct hlist_head *head,
307						    const unsigned char *addr)
308{
309	struct hlist_node *h;
310	struct net_bridge_fdb_entry *fdb;
311
312	hlist_for_each_entry_rcu(fdb, h, head, hlist) {
313		if (!compare_ether_addr(fdb->addr.addr, addr))
314			return fdb;
315	}
316	return NULL;
317}
318
319static struct net_bridge_fdb_entry *fdb_create(struct hlist_head *head,
320					       struct net_bridge_port *source,
321					       const unsigned char *addr,
322					       int is_local)
323{
324	struct net_bridge_fdb_entry *fdb;
325
326	fdb = kmem_cache_alloc(br_fdb_cache, GFP_ATOMIC);
327	if (fdb) {
328		memcpy(fdb->addr.addr, addr, ETH_ALEN);
329		hlist_add_head_rcu(&fdb->hlist, head);
330
331		fdb->dst = source;
332		fdb->is_local = is_local;
333		fdb->is_static = is_local;
334		fdb->ageing_timer = jiffies;
335	}
336	return fdb;
337}
338
339static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
340		  const unsigned char *addr)
341{
342	struct hlist_head *head = &br->hash[br_mac_hash(addr)];
343	struct net_bridge_fdb_entry *fdb;
344
345	if (!is_valid_ether_addr(addr))
346		return -EINVAL;
347
348	fdb = fdb_find(head, addr);
349	if (fdb) {
350		/* it is okay to have multiple ports with same
351		 * address, just use the first one.
352		 */
353		if (fdb->is_local)
354			return 0;
355
356		printk(KERN_WARNING "%s adding interface with same address "
357		       "as a received packet\n",
358		       source->dev->name);
359		fdb_delete(fdb);
360	}
361
362	if (!fdb_create(head, source, addr, 1))
363		return -ENOMEM;
364
365	return 0;
366}
367
368int br_fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
369		  const unsigned char *addr)
370{
371	int ret;
372
373	spin_lock_bh(&br->hash_lock);
374	ret = fdb_insert(br, source, addr);
375	spin_unlock_bh(&br->hash_lock);
376	return ret;
377}
378
379void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
380		   const unsigned char *addr)
381{
382	struct hlist_head *head = &br->hash[br_mac_hash(addr)];
383	struct net_bridge_fdb_entry *fdb;
384
385	/* some users want to always flood. */
386	if (hold_time(br) == 0)
387		return;
388
389	/* ignore packets unless we are using this port */
390	if (!(source->state == BR_STATE_LEARNING ||
391	      source->state == BR_STATE_FORWARDING))
392		return;
393
394	fdb = fdb_find(head, addr);
395	if (likely(fdb)) {
396		/* attempt to update an entry for a local interface */
397		if (unlikely(fdb->is_local)) {
398			if (net_ratelimit())
399				printk(KERN_WARNING "%s: received packet with "
400				       "own address as source address\n",
401				       source->dev->name);
402		} else {
403			/* fastpath: update of existing entry */
404			fdb->dst = source;
405			fdb->ageing_timer = jiffies;
406		}
407	} else {
408		spin_lock(&br->hash_lock);
409		if (!fdb_find(head, addr))
410			fdb_create(head, source, addr, 0);
411		/* else  we lose race and someone else inserts
412		 * it first, don't bother updating
413		 */
414		spin_unlock(&br->hash_lock);
415	}
416}
417