br_fdb.c revision 81bdf5bd7349bd4523538cbd7878f334bc2bfe14 
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->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 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->forward_delay;
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->ageing_timer + 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	/* Add HZ/4 to ensure we round the jiffies upwards to be after the next
153	 * timer, otherwise we might round down and will have no-op run. */
154	mod_timer(&br->gc_timer, round_jiffies(next_timer + HZ/4));
155}
156
157/* Completely flush all dynamic entries in forwarding database.*/
158void br_fdb_flush(struct net_bridge *br)
159{
160	int i;
161
162	spin_lock_bh(&br->hash_lock);
163	for (i = 0; i < BR_HASH_SIZE; i++) {
164		struct net_bridge_fdb_entry *f;
165		struct hlist_node *h, *n;
166		hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
167			if (!f->is_static)
168				fdb_delete(f);
169		}
170	}
171	spin_unlock_bh(&br->hash_lock);
172}
173
174/* Flush all entries refering to a specific port.
175 * if do_all is set also flush static entries
176 */
177void br_fdb_delete_by_port(struct net_bridge *br,
178			   const struct net_bridge_port *p,
179			   int do_all)
180{
181	int i;
182
183	spin_lock_bh(&br->hash_lock);
184	for (i = 0; i < BR_HASH_SIZE; i++) {
185		struct hlist_node *h, *g;
186
187		hlist_for_each_safe(h, g, &br->hash[i]) {
188			struct net_bridge_fdb_entry *f
189				= hlist_entry(h, struct net_bridge_fdb_entry, hlist);
190			if (f->dst != p)
191				continue;
192
193			if (f->is_static && !do_all)
194				continue;
195			/*
196			 * if multiple ports all have the same device address
197			 * then when one port is deleted, assign
198			 * the local entry to other port
199			 */
200			if (f->is_local) {
201				struct net_bridge_port *op;
202				list_for_each_entry(op, &br->port_list, list) {
203					if (op != p &&
204					    !compare_ether_addr(op->dev->dev_addr,
205								f->addr.addr)) {
206						f->dst = op;
207						goto skip_delete;
208					}
209				}
210			}
211
212			fdb_delete(f);
213		skip_delete: ;
214		}
215	}
216	spin_unlock_bh(&br->hash_lock);
217}
218
219/* No locking or refcounting, assumes caller has no preempt (rcu_read_lock) */
220struct net_bridge_fdb_entry *__br_fdb_get(struct net_bridge *br,
221					  const unsigned char *addr)
222{
223	struct hlist_node *h;
224	struct net_bridge_fdb_entry *fdb;
225
226	hlist_for_each_entry_rcu(fdb, h, &br->hash[br_mac_hash(addr)], hlist) {
227		if (!compare_ether_addr(fdb->addr.addr, addr)) {
228			if (unlikely(has_expired(br, fdb)))
229				break;
230			return fdb;
231		}
232	}
233
234	return NULL;
235}
236
237#if defined(CONFIG_ATM_LANE) || defined(CONFIG_ATM_LANE_MODULE)
238/* Interface used by ATM LANE hook to test
239 * if an addr is on some other bridge port */
240int br_fdb_test_addr(struct net_device *dev, unsigned char *addr)
241{
242	struct net_bridge_fdb_entry *fdb;
243	int ret;
244
245	if (!dev->br_port)
246		return 0;
247
248	rcu_read_lock();
249	fdb = __br_fdb_get(br_port(dev)->br, addr);
250	ret = fdb && fdb->dst->dev != dev &&
251		fdb->dst->state == BR_STATE_FORWARDING;
252	rcu_read_unlock();
253
254	return ret;
255}
256#endif /* CONFIG_ATM_LANE */
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
289			/* due to ABI compat need to split into hi/lo */
290			fe->port_no = f->dst->port_no;
291			fe->port_hi = f->dst->port_no >> 8;
292
293			fe->is_local = f->is_local;
294			if (!f->is_static)
295				fe->ageing_timer_value = jiffies_to_clock_t(jiffies - f->ageing_timer);
296			++fe;
297			++num;
298		}
299	}
300
301 out:
302	rcu_read_unlock();
303
304	return num;
305}
306
307static inline struct net_bridge_fdb_entry *fdb_find(struct hlist_head *head,
308						    const unsigned char *addr)
309{
310	struct hlist_node *h;
311	struct net_bridge_fdb_entry *fdb;
312
313	hlist_for_each_entry_rcu(fdb, h, head, hlist) {
314		if (!compare_ether_addr(fdb->addr.addr, addr))
315			return fdb;
316	}
317	return NULL;
318}
319
320static struct net_bridge_fdb_entry *fdb_create(struct hlist_head *head,
321					       struct net_bridge_port *source,
322					       const unsigned char *addr,
323					       int is_local)
324{
325	struct net_bridge_fdb_entry *fdb;
326
327	fdb = kmem_cache_alloc(br_fdb_cache, GFP_ATOMIC);
328	if (fdb) {
329		memcpy(fdb->addr.addr, addr, ETH_ALEN);
330		hlist_add_head_rcu(&fdb->hlist, head);
331
332		fdb->dst = source;
333		fdb->is_local = is_local;
334		fdb->is_static = is_local;
335		fdb->ageing_timer = jiffies;
336	}
337	return fdb;
338}
339
340static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
341		  const unsigned char *addr)
342{
343	struct hlist_head *head = &br->hash[br_mac_hash(addr)];
344	struct net_bridge_fdb_entry *fdb;
345
346	if (!is_valid_ether_addr(addr))
347		return -EINVAL;
348
349	fdb = fdb_find(head, addr);
350	if (fdb) {
351		/* it is okay to have multiple ports with same
352		 * address, just use the first one.
353		 */
354		if (fdb->is_local)
355			return 0;
356		br_warn(br, "adding interface %s 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				br_warn(br, "received packet on %s 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