br_fdb.c revision 0b040829952d84bf2a62526f0e24b624e0699447 
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/spinlock.h>
17#include <linux/times.h>
18#include <linux/netdevice.h>
19#include <linux/etherdevice.h>
20#include <linux/jhash.h>
21#include <linux/random.h>
22#include <asm/atomic.h>
23#include <asm/unaligned.h>
24#include "br_private.h"
25
26static struct kmem_cache *br_fdb_cache __read_mostly;
27static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
28		      const unsigned char *addr);
29
30static u32 fdb_salt __read_mostly;
31
32int __init br_fdb_init(void)
33{
34	br_fdb_cache = kmem_cache_create("bridge_fdb_cache",
35					 sizeof(struct net_bridge_fdb_entry),
36					 0,
37					 SLAB_HWCACHE_ALIGN, NULL);
38	if (!br_fdb_cache)
39		return -ENOMEM;
40
41	get_random_bytes(&fdb_salt, sizeof(fdb_salt));
42	return 0;
43}
44
45void br_fdb_fini(void)
46{
47	kmem_cache_destroy(br_fdb_cache);
48}
49
50
51/* if topology_changing then use forward_delay (default 15 sec)
52 * otherwise keep longer (default 5 minutes)
53 */
54static inline unsigned long hold_time(const struct net_bridge *br)
55{
56	return br->topology_change ? br->forward_delay : br->ageing_time;
57}
58
59static inline int has_expired(const struct net_bridge *br,
60				  const struct net_bridge_fdb_entry *fdb)
61{
62	return !fdb->is_static
63		&& time_before_eq(fdb->ageing_timer + hold_time(br), jiffies);
64}
65
66static inline int br_mac_hash(const unsigned char *mac)
67{
68	/* use 1 byte of OUI cnd 3 bytes of NIC */
69	u32 key = get_unaligned((u32 *)(mac + 2));
70	return jhash_1word(key, fdb_salt) & (BR_HASH_SIZE - 1);
71}
72
73static inline void fdb_delete(struct net_bridge_fdb_entry *f)
74{
75	hlist_del_rcu(&f->hlist);
76	br_fdb_put(f);
77}
78
79void br_fdb_changeaddr(struct net_bridge_port *p, const unsigned char *newaddr)
80{
81	struct net_bridge *br = p->br;
82	int i;
83
84	spin_lock_bh(&br->hash_lock);
85
86	/* Search all chains since old address/hash is unknown */
87	for (i = 0; i < BR_HASH_SIZE; i++) {
88		struct hlist_node *h;
89		hlist_for_each(h, &br->hash[i]) {
90			struct net_bridge_fdb_entry *f;
91
92			f = hlist_entry(h, struct net_bridge_fdb_entry, hlist);
93			if (f->dst == p && f->is_local) {
94				/* maybe another port has same hw addr? */
95				struct net_bridge_port *op;
96				list_for_each_entry(op, &br->port_list, list) {
97					if (op != p &&
98					    !compare_ether_addr(op->dev->dev_addr,
99								f->addr.addr)) {
100						f->dst = op;
101						goto insert;
102					}
103				}
104
105				/* delete old one */
106				fdb_delete(f);
107				goto insert;
108			}
109		}
110	}
111 insert:
112	/* insert new address,  may fail if invalid address or dup. */
113	fdb_insert(br, p, newaddr);
114
115	spin_unlock_bh(&br->hash_lock);
116}
117
118void br_fdb_cleanup(unsigned long _data)
119{
120	struct net_bridge *br = (struct net_bridge *)_data;
121	unsigned long delay = hold_time(br);
122	unsigned long next_timer = jiffies + br->forward_delay;
123	int i;
124
125	spin_lock_bh(&br->hash_lock);
126	for (i = 0; i < BR_HASH_SIZE; i++) {
127		struct net_bridge_fdb_entry *f;
128		struct hlist_node *h, *n;
129
130		hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
131			unsigned long this_timer;
132			if (f->is_static)
133				continue;
134			this_timer = f->ageing_timer + delay;
135			if (time_before_eq(this_timer, jiffies))
136				fdb_delete(f);
137			else if (time_before(this_timer, next_timer))
138				next_timer = this_timer;
139		}
140	}
141	spin_unlock_bh(&br->hash_lock);
142
143	/* Add HZ/4 to ensure we round the jiffies upwards to be after the next
144	 * timer, otherwise we might round down and will have no-op run. */
145	mod_timer(&br->gc_timer, round_jiffies(next_timer + HZ/4));
146}
147
148/* Completely flush all dynamic entries in forwarding database.*/
149void br_fdb_flush(struct net_bridge *br)
150{
151	int i;
152
153	spin_lock_bh(&br->hash_lock);
154	for (i = 0; i < BR_HASH_SIZE; i++) {
155		struct net_bridge_fdb_entry *f;
156		struct hlist_node *h, *n;
157		hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
158			if (!f->is_static)
159				fdb_delete(f);
160		}
161	}
162	spin_unlock_bh(&br->hash_lock);
163}
164
165/* Flush all entries refering to a specific port.
166 * if do_all is set also flush static entries
167 */
168void br_fdb_delete_by_port(struct net_bridge *br,
169			   const struct net_bridge_port *p,
170			   int do_all)
171{
172	int i;
173
174	spin_lock_bh(&br->hash_lock);
175	for (i = 0; i < BR_HASH_SIZE; i++) {
176		struct hlist_node *h, *g;
177
178		hlist_for_each_safe(h, g, &br->hash[i]) {
179			struct net_bridge_fdb_entry *f
180				= hlist_entry(h, struct net_bridge_fdb_entry, hlist);
181			if (f->dst != p)
182				continue;
183
184			if (f->is_static && !do_all)
185				continue;
186			/*
187			 * if multiple ports all have the same device address
188			 * then when one port is deleted, assign
189			 * the local entry to other port
190			 */
191			if (f->is_local) {
192				struct net_bridge_port *op;
193				list_for_each_entry(op, &br->port_list, list) {
194					if (op != p &&
195					    !compare_ether_addr(op->dev->dev_addr,
196								f->addr.addr)) {
197						f->dst = op;
198						goto skip_delete;
199					}
200				}
201			}
202
203			fdb_delete(f);
204		skip_delete: ;
205		}
206	}
207	spin_unlock_bh(&br->hash_lock);
208}
209
210/* No locking or refcounting, assumes caller has no preempt (rcu_read_lock) */
211struct net_bridge_fdb_entry *__br_fdb_get(struct net_bridge *br,
212					  const unsigned char *addr)
213{
214	struct hlist_node *h;
215	struct net_bridge_fdb_entry *fdb;
216
217	hlist_for_each_entry_rcu(fdb, h, &br->hash[br_mac_hash(addr)], hlist) {
218		if (!compare_ether_addr(fdb->addr.addr, addr)) {
219			if (unlikely(has_expired(br, fdb)))
220				break;
221			return fdb;
222		}
223	}
224
225	return NULL;
226}
227
228/* Interface used by ATM hook that keeps a ref count */
229struct net_bridge_fdb_entry *br_fdb_get(struct net_bridge *br,
230					unsigned char *addr)
231{
232	struct net_bridge_fdb_entry *fdb;
233
234	rcu_read_lock();
235	fdb = __br_fdb_get(br, addr);
236	if (fdb && !atomic_inc_not_zero(&fdb->use_count))
237		fdb = NULL;
238	rcu_read_unlock();
239	return fdb;
240}
241
242static void fdb_rcu_free(struct rcu_head *head)
243{
244	struct net_bridge_fdb_entry *ent
245		= container_of(head, struct net_bridge_fdb_entry, rcu);
246	kmem_cache_free(br_fdb_cache, ent);
247}
248
249/* Set entry up for deletion with RCU  */
250void br_fdb_put(struct net_bridge_fdb_entry *ent)
251{
252	if (atomic_dec_and_test(&ent->use_count))
253		call_rcu(&ent->rcu, fdb_rcu_free);
254}
255
256/*
257 * Fill buffer with forwarding table records in
258 * the API format.
259 */
260int br_fdb_fillbuf(struct net_bridge *br, void *buf,
261		   unsigned long maxnum, unsigned long skip)
262{
263	struct __fdb_entry *fe = buf;
264	int i, num = 0;
265	struct hlist_node *h;
266	struct net_bridge_fdb_entry *f;
267
268	memset(buf, 0, maxnum*sizeof(struct __fdb_entry));
269
270	rcu_read_lock();
271	for (i = 0; i < BR_HASH_SIZE; i++) {
272		hlist_for_each_entry_rcu(f, h, &br->hash[i], hlist) {
273			if (num >= maxnum)
274				goto out;
275
276			if (has_expired(br, f))
277				continue;
278
279			if (skip) {
280				--skip;
281				continue;
282			}
283
284			/* convert from internal format to API */
285			memcpy(fe->mac_addr, f->addr.addr, ETH_ALEN);
286
287			/* due to ABI compat need to split into hi/lo */
288			fe->port_no = f->dst->port_no;
289			fe->port_hi = f->dst->port_no >> 8;
290
291			fe->is_local = f->is_local;
292			if (!f->is_static)
293				fe->ageing_timer_value = jiffies_to_clock_t(jiffies - f->ageing_timer);
294			++fe;
295			++num;
296		}
297	}
298
299 out:
300	rcu_read_unlock();
301
302	return num;
303}
304
305static inline struct net_bridge_fdb_entry *fdb_find(struct hlist_head *head,
306						    const unsigned char *addr)
307{
308	struct hlist_node *h;
309	struct net_bridge_fdb_entry *fdb;
310
311	hlist_for_each_entry_rcu(fdb, h, head, hlist) {
312		if (!compare_ether_addr(fdb->addr.addr, addr))
313			return fdb;
314	}
315	return NULL;
316}
317
318static struct net_bridge_fdb_entry *fdb_create(struct hlist_head *head,
319					       struct net_bridge_port *source,
320					       const unsigned char *addr,
321					       int is_local)
322{
323	struct net_bridge_fdb_entry *fdb;
324
325	fdb = kmem_cache_alloc(br_fdb_cache, GFP_ATOMIC);
326	if (fdb) {
327		memcpy(fdb->addr.addr, addr, ETH_ALEN);
328		atomic_set(&fdb->use_count, 1);
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