br_fdb.c revision df1c0b8468b34628ed12b103804a4576cd9af8bb 
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 <linux/random.h>
24#include <asm/atomic.h>
25#include <asm/unaligned.h>
26#include "br_private.h"
27
28static struct kmem_cache *br_fdb_cache __read_mostly;
29static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
30		      const unsigned char *addr);
31
32static u32 fdb_salt __read_mostly;
33
34int __init br_fdb_init(void)
35{
36	br_fdb_cache = kmem_cache_create("bridge_fdb_cache",
37					 sizeof(struct net_bridge_fdb_entry),
38					 0,
39					 SLAB_HWCACHE_ALIGN, NULL);
40	if (!br_fdb_cache)
41		return -ENOMEM;
42
43	get_random_bytes(&fdb_salt, sizeof(fdb_salt));
44	return 0;
45}
46
47void __exit br_fdb_fini(void)
48{
49	kmem_cache_destroy(br_fdb_cache);
50}
51
52
53/* if topology_changing then use forward_delay (default 15 sec)
54 * otherwise keep longer (default 5 minutes)
55 */
56static inline unsigned long hold_time(const struct net_bridge *br)
57{
58	return br->topology_change ? br->forward_delay : br->ageing_time;
59}
60
61static inline int has_expired(const struct net_bridge *br,
62				  const struct net_bridge_fdb_entry *fdb)
63{
64	return !fdb->is_static
65		&& time_before_eq(fdb->ageing_timer + hold_time(br), jiffies);
66}
67
68static inline int br_mac_hash(const unsigned char *mac)
69{
70	/* use 1 byte of OUI cnd 3 bytes of NIC */
71	u32 key = get_unaligned((u32 *)(mac + 2));
72	return jhash_1word(key, fdb_salt) & (BR_HASH_SIZE - 1);
73}
74
75static inline void fdb_delete(struct net_bridge_fdb_entry *f)
76{
77	hlist_del_rcu(&f->hlist);
78	br_fdb_put(f);
79}
80
81void br_fdb_changeaddr(struct net_bridge_port *p, const unsigned char *newaddr)
82{
83	struct net_bridge *br = p->br;
84	int i;
85
86	spin_lock_bh(&br->hash_lock);
87
88	/* Search all chains since old address/hash is unknown */
89	for (i = 0; i < BR_HASH_SIZE; i++) {
90		struct hlist_node *h;
91		hlist_for_each(h, &br->hash[i]) {
92			struct net_bridge_fdb_entry *f;
93
94			f = hlist_entry(h, struct net_bridge_fdb_entry, hlist);
95			if (f->dst == p && f->is_local) {
96				/* maybe another port has same hw addr? */
97				struct net_bridge_port *op;
98				list_for_each_entry(op, &br->port_list, list) {
99					if (op != p &&
100					    !compare_ether_addr(op->dev->dev_addr,
101								f->addr.addr)) {
102						f->dst = op;
103						goto insert;
104					}
105				}
106
107				/* delete old one */
108				fdb_delete(f);
109				goto insert;
110			}
111		}
112	}
113 insert:
114	/* insert new address,  may fail if invalid address or dup. */
115	fdb_insert(br, p, newaddr);
116
117	spin_unlock_bh(&br->hash_lock);
118}
119
120void br_fdb_cleanup(unsigned long _data)
121{
122	struct net_bridge *br = (struct net_bridge *)_data;
123	unsigned long delay = hold_time(br);
124	unsigned long next_timer = jiffies + br->forward_delay;
125	int i;
126
127	spin_lock_bh(&br->hash_lock);
128	for (i = 0; i < BR_HASH_SIZE; i++) {
129		struct net_bridge_fdb_entry *f;
130		struct hlist_node *h, *n;
131
132		hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
133			unsigned long this_timer;
134			if (f->is_static)
135				continue;
136			this_timer = f->ageing_timer + delay;
137			if (time_before_eq(this_timer, jiffies))
138				fdb_delete(f);
139			else if (this_timer < next_timer)
140				next_timer = this_timer;
141		}
142	}
143	spin_unlock_bh(&br->hash_lock);
144
145	/* Add HZ/4 to ensure we round the jiffies upwards to be after the next
146	 * timer, otherwise we might round down and will have no-op run. */
147	mod_timer(&br->gc_timer, round_jiffies(next_timer + HZ/4));
148}
149
150/* Completely flush all dynamic entries in forwarding database.*/
151void br_fdb_flush(struct net_bridge *br)
152{
153	int i;
154
155	spin_lock_bh(&br->hash_lock);
156	for (i = 0; i < BR_HASH_SIZE; i++) {
157		struct net_bridge_fdb_entry *f;
158		struct hlist_node *h, *n;
159		hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
160			if (!f->is_static)
161				fdb_delete(f);
162		}
163	}
164	spin_unlock_bh(&br->hash_lock);
165}
166
167/* Flush all entries refering to a specific port.
168 * if do_all is set also flush static entries
169 */
170void br_fdb_delete_by_port(struct net_bridge *br,
171			   const struct net_bridge_port *p,
172			   int do_all)
173{
174	int i;
175
176	spin_lock_bh(&br->hash_lock);
177	for (i = 0; i < BR_HASH_SIZE; i++) {
178		struct hlist_node *h, *g;
179
180		hlist_for_each_safe(h, g, &br->hash[i]) {
181			struct net_bridge_fdb_entry *f
182				= hlist_entry(h, struct net_bridge_fdb_entry, hlist);
183			if (f->dst != p)
184				continue;
185
186			if (f->is_static && !do_all)
187				continue;
188			/*
189			 * if multiple ports all have the same device address
190			 * then when one port is deleted, assign
191			 * the local entry to other port
192			 */
193			if (f->is_local) {
194				struct net_bridge_port *op;
195				list_for_each_entry(op, &br->port_list, list) {
196					if (op != p &&
197					    !compare_ether_addr(op->dev->dev_addr,
198								f->addr.addr)) {
199						f->dst = op;
200						goto skip_delete;
201					}
202				}
203			}
204
205			fdb_delete(f);
206		skip_delete: ;
207		}
208	}
209	spin_unlock_bh(&br->hash_lock);
210}
211
212/* No locking or refcounting, assumes caller has no preempt (rcu_read_lock) */
213struct net_bridge_fdb_entry *__br_fdb_get(struct net_bridge *br,
214					  const unsigned char *addr)
215{
216	struct hlist_node *h;
217	struct net_bridge_fdb_entry *fdb;
218
219	hlist_for_each_entry_rcu(fdb, h, &br->hash[br_mac_hash(addr)], hlist) {
220		if (!compare_ether_addr(fdb->addr.addr, addr)) {
221			if (unlikely(has_expired(br, fdb)))
222				break;
223			return fdb;
224		}
225	}
226
227	return NULL;
228}
229
230/* Interface used by ATM hook that keeps a ref count */
231struct net_bridge_fdb_entry *br_fdb_get(struct net_bridge *br,
232					unsigned char *addr)
233{
234	struct net_bridge_fdb_entry *fdb;
235
236	rcu_read_lock();
237	fdb = __br_fdb_get(br, addr);
238	if (fdb && !atomic_inc_not_zero(&fdb->use_count))
239		fdb = NULL;
240	rcu_read_unlock();
241	return fdb;
242}
243
244static void fdb_rcu_free(struct rcu_head *head)
245{
246	struct net_bridge_fdb_entry *ent
247		= container_of(head, struct net_bridge_fdb_entry, rcu);
248	kmem_cache_free(br_fdb_cache, ent);
249}
250
251/* Set entry up for deletion with RCU  */
252void br_fdb_put(struct net_bridge_fdb_entry *ent)
253{
254	if (atomic_dec_and_test(&ent->use_count))
255		call_rcu(&ent->rcu, fdb_rcu_free);
256}
257
258/*
259 * Fill buffer with forwarding table records in
260 * the API format.
261 */
262int br_fdb_fillbuf(struct net_bridge *br, void *buf,
263		   unsigned long maxnum, unsigned long skip)
264{
265	struct __fdb_entry *fe = buf;
266	int i, num = 0;
267	struct hlist_node *h;
268	struct net_bridge_fdb_entry *f;
269
270	memset(buf, 0, maxnum*sizeof(struct __fdb_entry));
271
272	rcu_read_lock();
273	for (i = 0; i < BR_HASH_SIZE; i++) {
274		hlist_for_each_entry_rcu(f, h, &br->hash[i], hlist) {
275			if (num >= maxnum)
276				goto out;
277
278			if (has_expired(br, f))
279				continue;
280
281			if (skip) {
282				--skip;
283				continue;
284			}
285
286			/* convert from internal format to API */
287			memcpy(fe->mac_addr, f->addr.addr, ETH_ALEN);
288			fe->port_no = f->dst->port_no;
289			fe->is_local = f->is_local;
290			if (!f->is_static)
291				fe->ageing_timer_value = jiffies_to_clock_t(jiffies - f->ageing_timer);
292			++fe;
293			++num;
294		}
295	}
296
297 out:
298	rcu_read_unlock();
299
300	return num;
301}
302
303static inline struct net_bridge_fdb_entry *fdb_find(struct hlist_head *head,
304						    const unsigned char *addr)
305{
306	struct hlist_node *h;
307	struct net_bridge_fdb_entry *fdb;
308
309	hlist_for_each_entry_rcu(fdb, h, head, hlist) {
310		if (!compare_ether_addr(fdb->addr.addr, addr))
311			return fdb;
312	}
313	return NULL;
314}
315
316static struct net_bridge_fdb_entry *fdb_create(struct hlist_head *head,
317					       struct net_bridge_port *source,
318					       const unsigned char *addr,
319					       int is_local)
320{
321	struct net_bridge_fdb_entry *fdb;
322
323	fdb = kmem_cache_alloc(br_fdb_cache, GFP_ATOMIC);
324	if (fdb) {
325		memcpy(fdb->addr.addr, addr, ETH_ALEN);
326		atomic_set(&fdb->use_count, 1);
327		hlist_add_head_rcu(&fdb->hlist, head);
328
329		fdb->dst = source;
330		fdb->is_local = is_local;
331		fdb->is_static = is_local;
332		fdb->ageing_timer = jiffies;
333	}
334	return fdb;
335}
336
337static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
338		  const unsigned char *addr)
339{
340	struct hlist_head *head = &br->hash[br_mac_hash(addr)];
341	struct net_bridge_fdb_entry *fdb;
342
343	if (!is_valid_ether_addr(addr))
344		return -EINVAL;
345
346	fdb = fdb_find(head, addr);
347	if (fdb) {
348		/* it is okay to have multiple ports with same
349		 * address, just use the first one.
350		 */
351		if (fdb->is_local)
352			return 0;
353
354		printk(KERN_WARNING "%s adding interface with same address "
355		       "as a received packet\n",
356		       source->dev->name);
357		fdb_delete(fdb);
358	}
359
360	if (!fdb_create(head, source, addr, 1))
361		return -ENOMEM;
362
363	return 0;
364}
365
366int br_fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
367		  const unsigned char *addr)
368{
369	int ret;
370
371	spin_lock_bh(&br->hash_lock);
372	ret = fdb_insert(br, source, addr);
373	spin_unlock_bh(&br->hash_lock);
374	return ret;
375}
376
377void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
378		   const unsigned char *addr)
379{
380	struct hlist_head *head = &br->hash[br_mac_hash(addr)];
381	struct net_bridge_fdb_entry *fdb;
382
383	/* some users want to always flood. */
384	if (hold_time(br) == 0)
385		return;
386
387	/* ignore packets unless we are using this port */
388	if (!(source->state == BR_STATE_LEARNING ||
389	      source->state == BR_STATE_FORWARDING))
390		return;
391
392	fdb = fdb_find(head, addr);
393	if (likely(fdb)) {
394		/* attempt to update an entry for a local interface */
395		if (unlikely(fdb->is_local)) {
396			if (net_ratelimit())
397				printk(KERN_WARNING "%s: received packet with "
398				       " own address as source address\n",
399				       source->dev->name);
400		} else {
401			/* fastpath: update of existing entry */
402			fdb->dst = source;
403			fdb->ageing_timer = jiffies;
404		}
405	} else {
406		spin_lock(&br->hash_lock);
407		if (!fdb_find(head, addr))
408			fdb_create(head, source, addr, 0);
409		/* else  we lose race and someone else inserts
410		 * it first, don't bother updating
411		 */
412		spin_unlock(&br->hash_lock);
413	}
414}
415