br_fdb.c revision 664de48bb6c4e167fcdf92a4bddf880030fbfbb3 
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 <linux/slab.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 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->updated + 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 void fdb_rcu_free(struct rcu_head *head)
76{
77	struct net_bridge_fdb_entry *ent
78		= container_of(head, struct net_bridge_fdb_entry, rcu);
79	kmem_cache_free(br_fdb_cache, ent);
80}
81
82static inline void fdb_delete(struct net_bridge_fdb_entry *f)
83{
84	hlist_del_rcu(&f->hlist);
85	call_rcu(&f->rcu, fdb_rcu_free);
86}
87
88void br_fdb_changeaddr(struct net_bridge_port *p, const unsigned char *newaddr)
89{
90	struct net_bridge *br = p->br;
91	int i;
92
93	spin_lock_bh(&br->hash_lock);
94
95	/* Search all chains since old address/hash is unknown */
96	for (i = 0; i < BR_HASH_SIZE; i++) {
97		struct hlist_node *h;
98		hlist_for_each(h, &br->hash[i]) {
99			struct net_bridge_fdb_entry *f;
100
101			f = hlist_entry(h, struct net_bridge_fdb_entry, hlist);
102			if (f->dst == p && f->is_local) {
103				/* maybe another port has same hw addr? */
104				struct net_bridge_port *op;
105				list_for_each_entry(op, &br->port_list, list) {
106					if (op != p &&
107					    !compare_ether_addr(op->dev->dev_addr,
108								f->addr.addr)) {
109						f->dst = op;
110						goto insert;
111					}
112				}
113
114				/* delete old one */
115				fdb_delete(f);
116				goto insert;
117			}
118		}
119	}
120 insert:
121	/* insert new address,  may fail if invalid address or dup. */
122	fdb_insert(br, p, newaddr);
123
124	spin_unlock_bh(&br->hash_lock);
125}
126
127void br_fdb_cleanup(unsigned long _data)
128{
129	struct net_bridge *br = (struct net_bridge *)_data;
130	unsigned long delay = hold_time(br);
131	unsigned long next_timer = jiffies + br->ageing_time;
132	int i;
133
134	spin_lock_bh(&br->hash_lock);
135	for (i = 0; i < BR_HASH_SIZE; i++) {
136		struct net_bridge_fdb_entry *f;
137		struct hlist_node *h, *n;
138
139		hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
140			unsigned long this_timer;
141			if (f->is_static)
142				continue;
143			this_timer = f->updated + delay;
144			if (time_before_eq(this_timer, jiffies))
145				fdb_delete(f);
146			else if (time_before(this_timer, next_timer))
147				next_timer = this_timer;
148		}
149	}
150	spin_unlock_bh(&br->hash_lock);
151
152	mod_timer(&br->gc_timer, round_jiffies_up(next_timer));
153}
154
155/* Completely flush all dynamic entries in forwarding database.*/
156void br_fdb_flush(struct net_bridge *br)
157{
158	int i;
159
160	spin_lock_bh(&br->hash_lock);
161	for (i = 0; i < BR_HASH_SIZE; i++) {
162		struct net_bridge_fdb_entry *f;
163		struct hlist_node *h, *n;
164		hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
165			if (!f->is_static)
166				fdb_delete(f);
167		}
168	}
169	spin_unlock_bh(&br->hash_lock);
170}
171
172/* Flush all entries refering to a specific port.
173 * if do_all is set also flush static entries
174 */
175void br_fdb_delete_by_port(struct net_bridge *br,
176			   const struct net_bridge_port *p,
177			   int do_all)
178{
179	int i;
180
181	spin_lock_bh(&br->hash_lock);
182	for (i = 0; i < BR_HASH_SIZE; i++) {
183		struct hlist_node *h, *g;
184
185		hlist_for_each_safe(h, g, &br->hash[i]) {
186			struct net_bridge_fdb_entry *f
187				= hlist_entry(h, struct net_bridge_fdb_entry, hlist);
188			if (f->dst != p)
189				continue;
190
191			if (f->is_static && !do_all)
192				continue;
193			/*
194			 * if multiple ports all have the same device address
195			 * then when one port is deleted, assign
196			 * the local entry to other port
197			 */
198			if (f->is_local) {
199				struct net_bridge_port *op;
200				list_for_each_entry(op, &br->port_list, list) {
201					if (op != p &&
202					    !compare_ether_addr(op->dev->dev_addr,
203								f->addr.addr)) {
204						f->dst = op;
205						goto skip_delete;
206					}
207				}
208			}
209
210			fdb_delete(f);
211		skip_delete: ;
212		}
213	}
214	spin_unlock_bh(&br->hash_lock);
215}
216
217/* No locking or refcounting, assumes caller has rcu_read_lock */
218struct net_bridge_fdb_entry *__br_fdb_get(struct net_bridge *br,
219					  const unsigned char *addr)
220{
221	struct hlist_node *h;
222	struct net_bridge_fdb_entry *fdb;
223
224	hlist_for_each_entry_rcu(fdb, h, &br->hash[br_mac_hash(addr)], hlist) {
225		if (!compare_ether_addr(fdb->addr.addr, addr)) {
226			if (unlikely(has_expired(br, fdb)))
227				break;
228			return fdb;
229		}
230	}
231
232	return NULL;
233}
234
235#if defined(CONFIG_ATM_LANE) || defined(CONFIG_ATM_LANE_MODULE)
236/* Interface used by ATM LANE hook to test
237 * if an addr is on some other bridge port */
238int br_fdb_test_addr(struct net_device *dev, unsigned char *addr)
239{
240	struct net_bridge_fdb_entry *fdb;
241	struct net_bridge_port *port;
242	int ret;
243
244	rcu_read_lock();
245	port = br_port_get_rcu(dev);
246	if (!port)
247		ret = 0;
248	else {
249		fdb = __br_fdb_get(port->br, addr);
250		ret = fdb && fdb->dst->dev != dev &&
251			fdb->dst->state == BR_STATE_FORWARDING;
252	}
253	rcu_read_unlock();
254
255	return ret;
256}
257#endif /* CONFIG_ATM_LANE */
258
259/*
260 * Fill buffer with forwarding table records in
261 * the API format.
262 */
263int br_fdb_fillbuf(struct net_bridge *br, void *buf,
264		   unsigned long maxnum, unsigned long skip)
265{
266	struct __fdb_entry *fe = buf;
267	int i, num = 0;
268	struct hlist_node *h;
269	struct net_bridge_fdb_entry *f;
270
271	memset(buf, 0, maxnum*sizeof(struct __fdb_entry));
272
273	rcu_read_lock();
274	for (i = 0; i < BR_HASH_SIZE; i++) {
275		hlist_for_each_entry_rcu(f, h, &br->hash[i], hlist) {
276			if (num >= maxnum)
277				goto out;
278
279			if (has_expired(br, f))
280				continue;
281
282			if (skip) {
283				--skip;
284				continue;
285			}
286
287			/* convert from internal format to API */
288			memcpy(fe->mac_addr, f->addr.addr, ETH_ALEN);
289
290			/* due to ABI compat need to split into hi/lo */
291			fe->port_no = f->dst->port_no;
292			fe->port_hi = f->dst->port_no >> 8;
293
294			fe->is_local = f->is_local;
295			if (!f->is_static)
296				fe->ageing_timer_value = jiffies_to_clock_t(jiffies - f->updated);
297			++fe;
298			++num;
299		}
300	}
301
302 out:
303	rcu_read_unlock();
304
305	return num;
306}
307
308static struct net_bridge_fdb_entry *fdb_find(struct hlist_head *head,
309					     const unsigned char *addr)
310{
311	struct hlist_node *h;
312	struct net_bridge_fdb_entry *fdb;
313
314	hlist_for_each_entry(fdb, h, head, hlist) {
315		if (!compare_ether_addr(fdb->addr.addr, addr))
316			return fdb;
317	}
318	return NULL;
319}
320
321static struct net_bridge_fdb_entry *fdb_find_rcu(struct hlist_head *head,
322						 const unsigned char *addr)
323{
324	struct hlist_node *h;
325	struct net_bridge_fdb_entry *fdb;
326
327	hlist_for_each_entry_rcu(fdb, h, head, hlist) {
328		if (!compare_ether_addr(fdb->addr.addr, addr))
329			return fdb;
330	}
331	return NULL;
332}
333
334static struct net_bridge_fdb_entry *fdb_create(struct hlist_head *head,
335					       struct net_bridge_port *source,
336					       const unsigned char *addr)
337{
338	struct net_bridge_fdb_entry *fdb;
339
340	fdb = kmem_cache_alloc(br_fdb_cache, GFP_ATOMIC);
341	if (fdb) {
342		memcpy(fdb->addr.addr, addr, ETH_ALEN);
343		fdb->dst = source;
344		fdb->is_local = 0;
345		fdb->is_static = 0;
346		fdb->updated = fdb->used = jiffies;
347		hlist_add_head_rcu(&fdb->hlist, head);
348	}
349	return fdb;
350}
351
352static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
353		  const unsigned char *addr)
354{
355	struct hlist_head *head = &br->hash[br_mac_hash(addr)];
356	struct net_bridge_fdb_entry *fdb;
357
358	if (!is_valid_ether_addr(addr))
359		return -EINVAL;
360
361	fdb = fdb_find(head, addr);
362	if (fdb) {
363		/* it is okay to have multiple ports with same
364		 * address, just use the first one.
365		 */
366		if (fdb->is_local)
367			return 0;
368		br_warn(br, "adding interface %s with same address "
369		       "as a received packet\n",
370		       source->dev->name);
371		fdb_delete(fdb);
372	}
373
374	fdb = fdb_create(head, source, addr);
375	if (!fdb)
376		return -ENOMEM;
377
378	fdb->is_local = fdb->is_static = 1;
379	return 0;
380}
381
382/* Add entry for local address of interface */
383int br_fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
384		  const unsigned char *addr)
385{
386	int ret;
387
388	spin_lock_bh(&br->hash_lock);
389	ret = fdb_insert(br, source, addr);
390	spin_unlock_bh(&br->hash_lock);
391	return ret;
392}
393
394void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
395		   const unsigned char *addr)
396{
397	struct hlist_head *head = &br->hash[br_mac_hash(addr)];
398	struct net_bridge_fdb_entry *fdb;
399
400	/* some users want to always flood. */
401	if (hold_time(br) == 0)
402		return;
403
404	/* ignore packets unless we are using this port */
405	if (!(source->state == BR_STATE_LEARNING ||
406	      source->state == BR_STATE_FORWARDING))
407		return;
408
409	fdb = fdb_find_rcu(head, addr);
410	if (likely(fdb)) {
411		/* attempt to update an entry for a local interface */
412		if (unlikely(fdb->is_local)) {
413			if (net_ratelimit())
414				br_warn(br, "received packet on %s with "
415					"own address as source address\n",
416					source->dev->name);
417		} else {
418			/* fastpath: update of existing entry */
419			fdb->dst = source;
420			fdb->updated = jiffies;
421		}
422	} else {
423		spin_lock(&br->hash_lock);
424		if (likely(!fdb_find(head, addr)))
425			fdb_create(head, source, addr);
426
427		/* else  we lose race and someone else inserts
428		 * it first, don't bother updating
429		 */
430		spin_unlock(&br->hash_lock);
431	}
432}
433