br_fdb.c revision 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 
1/*
2 *	Forwarding database
3 *	Linux ethernet bridge
4 *
5 *	Authors:
6 *	Lennert Buytenhek		<buytenh@gnu.org>
7 *
8 *	$Id: br_fdb.c,v 1.6 2002/01/17 00:57:07 davem Exp $
9 *
10 *	This program is free software; you can redistribute it and/or
11 *	modify it under the terms of the GNU General Public License
12 *	as published by the Free Software Foundation; either version
13 *	2 of the License, or (at your option) any later version.
14 */
15
16#include <linux/kernel.h>
17#include <linux/init.h>
18#include <linux/spinlock.h>
19#include <linux/times.h>
20#include <linux/netdevice.h>
21#include <linux/etherdevice.h>
22#include <linux/jhash.h>
23#include <asm/atomic.h>
24#include "br_private.h"
25
26static kmem_cache_t *br_fdb_cache;
27static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
28		      const unsigned char *addr);
29
30void __init br_fdb_init(void)
31{
32	br_fdb_cache = kmem_cache_create("bridge_fdb_cache",
33					 sizeof(struct net_bridge_fdb_entry),
34					 0,
35					 SLAB_HWCACHE_ALIGN, NULL, NULL);
36}
37
38void __exit br_fdb_fini(void)
39{
40	kmem_cache_destroy(br_fdb_cache);
41}
42
43
44/* if topology_changing then use forward_delay (default 15 sec)
45 * otherwise keep longer (default 5 minutes)
46 */
47static __inline__ unsigned long hold_time(const struct net_bridge *br)
48{
49	return br->topology_change ? br->forward_delay : br->ageing_time;
50}
51
52static __inline__ int has_expired(const struct net_bridge *br,
53				  const struct net_bridge_fdb_entry *fdb)
54{
55	return !fdb->is_static
56		&& time_before_eq(fdb->ageing_timer + hold_time(br), jiffies);
57}
58
59static __inline__ int br_mac_hash(const unsigned char *mac)
60{
61	return jhash(mac, ETH_ALEN, 0) & (BR_HASH_SIZE - 1);
62}
63
64static __inline__ void fdb_delete(struct net_bridge_fdb_entry *f)
65{
66	hlist_del_rcu(&f->hlist);
67	br_fdb_put(f);
68}
69
70void br_fdb_changeaddr(struct net_bridge_port *p, const unsigned char *newaddr)
71{
72	struct net_bridge *br = p->br;
73	int i;
74
75	spin_lock_bh(&br->hash_lock);
76
77	/* Search all chains since old address/hash is unknown */
78	for (i = 0; i < BR_HASH_SIZE; i++) {
79		struct hlist_node *h;
80		hlist_for_each(h, &br->hash[i]) {
81			struct net_bridge_fdb_entry *f;
82
83			f = hlist_entry(h, struct net_bridge_fdb_entry, hlist);
84			if (f->dst == p && f->is_local) {
85				/* maybe another port has same hw addr? */
86				struct net_bridge_port *op;
87				list_for_each_entry(op, &br->port_list, list) {
88					if (op != p &&
89					    !memcmp(op->dev->dev_addr,
90						    f->addr.addr, ETH_ALEN)) {
91						f->dst = op;
92						goto insert;
93					}
94				}
95
96				/* delete old one */
97				fdb_delete(f);
98				goto insert;
99			}
100		}
101	}
102 insert:
103	/* insert new address,  may fail if invalid address or dup. */
104	fdb_insert(br, p, newaddr);
105
106	spin_unlock_bh(&br->hash_lock);
107}
108
109void br_fdb_cleanup(unsigned long _data)
110{
111	struct net_bridge *br = (struct net_bridge *)_data;
112	unsigned long delay = hold_time(br);
113	int i;
114
115	spin_lock_bh(&br->hash_lock);
116	for (i = 0; i < BR_HASH_SIZE; i++) {
117		struct net_bridge_fdb_entry *f;
118		struct hlist_node *h, *n;
119
120		hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
121			if (!f->is_static &&
122			    time_before_eq(f->ageing_timer + delay, jiffies))
123				fdb_delete(f);
124		}
125	}
126	spin_unlock_bh(&br->hash_lock);
127
128	mod_timer(&br->gc_timer, jiffies + HZ/10);
129}
130
131void br_fdb_delete_by_port(struct net_bridge *br, struct net_bridge_port *p)
132{
133	int i;
134
135	spin_lock_bh(&br->hash_lock);
136	for (i = 0; i < BR_HASH_SIZE; i++) {
137		struct hlist_node *h, *g;
138
139		hlist_for_each_safe(h, g, &br->hash[i]) {
140			struct net_bridge_fdb_entry *f
141				= hlist_entry(h, struct net_bridge_fdb_entry, hlist);
142			if (f->dst != p)
143				continue;
144
145			/*
146			 * if multiple ports all have the same device address
147			 * then when one port is deleted, assign
148			 * the local entry to other port
149			 */
150			if (f->is_local) {
151				struct net_bridge_port *op;
152				list_for_each_entry(op, &br->port_list, list) {
153					if (op != p &&
154					    !memcmp(op->dev->dev_addr,
155						    f->addr.addr, ETH_ALEN)) {
156						f->dst = op;
157						goto skip_delete;
158					}
159				}
160			}
161
162			fdb_delete(f);
163		skip_delete: ;
164		}
165	}
166	spin_unlock_bh(&br->hash_lock);
167}
168
169/* No locking or refcounting, assumes caller has no preempt (rcu_read_lock) */
170struct net_bridge_fdb_entry *__br_fdb_get(struct net_bridge *br,
171					  const unsigned char *addr)
172{
173	struct hlist_node *h;
174	struct net_bridge_fdb_entry *fdb;
175
176	hlist_for_each_entry_rcu(fdb, h, &br->hash[br_mac_hash(addr)], hlist) {
177		if (!memcmp(fdb->addr.addr, addr, ETH_ALEN)) {
178			if (unlikely(has_expired(br, fdb)))
179				break;
180			return fdb;
181		}
182	}
183
184	return NULL;
185}
186
187/* Interface used by ATM hook that keeps a ref count */
188struct net_bridge_fdb_entry *br_fdb_get(struct net_bridge *br,
189					unsigned char *addr)
190{
191	struct net_bridge_fdb_entry *fdb;
192
193	rcu_read_lock();
194	fdb = __br_fdb_get(br, addr);
195	if (fdb)
196		atomic_inc(&fdb->use_count);
197	rcu_read_unlock();
198	return fdb;
199}
200
201static void fdb_rcu_free(struct rcu_head *head)
202{
203	struct net_bridge_fdb_entry *ent
204		= container_of(head, struct net_bridge_fdb_entry, rcu);
205	kmem_cache_free(br_fdb_cache, ent);
206}
207
208/* Set entry up for deletion with RCU  */
209void br_fdb_put(struct net_bridge_fdb_entry *ent)
210{
211	if (atomic_dec_and_test(&ent->use_count))
212		call_rcu(&ent->rcu, fdb_rcu_free);
213}
214
215/*
216 * Fill buffer with forwarding table records in
217 * the API format.
218 */
219int br_fdb_fillbuf(struct net_bridge *br, void *buf,
220		   unsigned long maxnum, unsigned long skip)
221{
222	struct __fdb_entry *fe = buf;
223	int i, num = 0;
224	struct hlist_node *h;
225	struct net_bridge_fdb_entry *f;
226
227	memset(buf, 0, maxnum*sizeof(struct __fdb_entry));
228
229	rcu_read_lock();
230	for (i = 0; i < BR_HASH_SIZE; i++) {
231		hlist_for_each_entry_rcu(f, h, &br->hash[i], hlist) {
232			if (num >= maxnum)
233				goto out;
234
235			if (has_expired(br, f))
236				continue;
237
238			if (skip) {
239				--skip;
240				continue;
241			}
242
243			/* convert from internal format to API */
244			memcpy(fe->mac_addr, f->addr.addr, ETH_ALEN);
245			fe->port_no = f->dst->port_no;
246			fe->is_local = f->is_local;
247			if (!f->is_static)
248				fe->ageing_timer_value = jiffies_to_clock_t(jiffies - f->ageing_timer);
249			++fe;
250			++num;
251		}
252	}
253
254 out:
255	rcu_read_unlock();
256
257	return num;
258}
259
260static inline struct net_bridge_fdb_entry *fdb_find(struct hlist_head *head,
261						    const unsigned char *addr)
262{
263	struct hlist_node *h;
264	struct net_bridge_fdb_entry *fdb;
265
266	hlist_for_each_entry_rcu(fdb, h, head, hlist) {
267		if (!memcmp(fdb->addr.addr, addr, ETH_ALEN))
268			return fdb;
269	}
270	return NULL;
271}
272
273static struct net_bridge_fdb_entry *fdb_create(struct hlist_head *head,
274					       struct net_bridge_port *source,
275					       const unsigned char *addr,
276					       int is_local)
277{
278	struct net_bridge_fdb_entry *fdb;
279
280	fdb = kmem_cache_alloc(br_fdb_cache, GFP_ATOMIC);
281	if (fdb) {
282		memcpy(fdb->addr.addr, addr, ETH_ALEN);
283		atomic_set(&fdb->use_count, 1);
284		hlist_add_head_rcu(&fdb->hlist, head);
285
286		fdb->dst = source;
287		fdb->is_local = is_local;
288		fdb->is_static = is_local;
289		fdb->ageing_timer = jiffies;
290	}
291	return fdb;
292}
293
294static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
295		  const unsigned char *addr)
296{
297	struct hlist_head *head = &br->hash[br_mac_hash(addr)];
298	struct net_bridge_fdb_entry *fdb;
299
300	if (!is_valid_ether_addr(addr))
301		return -EINVAL;
302
303	fdb = fdb_find(head, addr);
304	if (fdb) {
305		/* it is okay to have multiple ports with same
306		 * address, just use the first one.
307		 */
308		if (fdb->is_local)
309			return 0;
310
311		printk(KERN_WARNING "%s adding interface with same address "
312		       "as a received packet\n",
313		       source->dev->name);
314		fdb_delete(fdb);
315 	}
316
317	if (!fdb_create(head, source, addr, 1))
318		return -ENOMEM;
319
320	return 0;
321}
322
323int br_fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
324		  const unsigned char *addr)
325{
326	int ret;
327
328	spin_lock_bh(&br->hash_lock);
329	ret = fdb_insert(br, source, addr);
330	spin_unlock_bh(&br->hash_lock);
331	return ret;
332}
333
334void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
335		   const unsigned char *addr)
336{
337	struct hlist_head *head = &br->hash[br_mac_hash(addr)];
338	struct net_bridge_fdb_entry *fdb;
339
340	/* some users want to always flood. */
341	if (hold_time(br) == 0)
342		return;
343
344	rcu_read_lock();
345	fdb = fdb_find(head, addr);
346	if (likely(fdb)) {
347		/* attempt to update an entry for a local interface */
348		if (unlikely(fdb->is_local)) {
349			if (net_ratelimit())
350				printk(KERN_WARNING "%s: received packet with "
351				       " own address as source address\n",
352				       source->dev->name);
353		} else {
354			/* fastpath: update of existing entry */
355			fdb->dst = source;
356			fdb->ageing_timer = jiffies;
357		}
358	} else {
359		spin_lock_bh(&br->hash_lock);
360		if (!fdb_find(head, addr))
361			fdb_create(head, source, addr, 0);
362		/* else  we lose race and someone else inserts
363		 * it first, don't bother updating
364		 */
365		spin_unlock_bh(&br->hash_lock);
366	}
367	rcu_read_unlock();
368}
369