xref: /openbmc/linux/net/bridge/br_fdb.c (revision b6dcefde)
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 <asm/atomic.h>
24 #include <asm/unaligned.h>
25 #include "br_private.h"
26 
27 static struct kmem_cache *br_fdb_cache __read_mostly;
28 static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
29 		      const unsigned char *addr);
30 
31 static u32 fdb_salt __read_mostly;
32 
33 int __init br_fdb_init(void)
34 {
35 	br_fdb_cache = kmem_cache_create("bridge_fdb_cache",
36 					 sizeof(struct net_bridge_fdb_entry),
37 					 0,
38 					 SLAB_HWCACHE_ALIGN, NULL);
39 	if (!br_fdb_cache)
40 		return -ENOMEM;
41 
42 	get_random_bytes(&fdb_salt, sizeof(fdb_salt));
43 	return 0;
44 }
45 
46 void br_fdb_fini(void)
47 {
48 	kmem_cache_destroy(br_fdb_cache);
49 }
50 
51 
52 /* if topology_changing then use forward_delay (default 15 sec)
53  * otherwise keep longer (default 5 minutes)
54  */
55 static inline unsigned long hold_time(const struct net_bridge *br)
56 {
57 	return br->topology_change ? br->forward_delay : br->ageing_time;
58 }
59 
60 static inline int has_expired(const struct net_bridge *br,
61 				  const struct net_bridge_fdb_entry *fdb)
62 {
63 	return !fdb->is_static &&
64 		time_before_eq(fdb->ageing_timer + hold_time(br), jiffies);
65 }
66 
67 static inline int br_mac_hash(const unsigned char *mac)
68 {
69 	/* use 1 byte of OUI cnd 3 bytes of NIC */
70 	u32 key = get_unaligned((u32 *)(mac + 2));
71 	return jhash_1word(key, fdb_salt) & (BR_HASH_SIZE - 1);
72 }
73 
74 static void fdb_rcu_free(struct rcu_head *head)
75 {
76 	struct net_bridge_fdb_entry *ent
77 		= container_of(head, struct net_bridge_fdb_entry, rcu);
78 	kmem_cache_free(br_fdb_cache, ent);
79 }
80 
81 static inline void fdb_delete(struct net_bridge_fdb_entry *f)
82 {
83 	hlist_del_rcu(&f->hlist);
84 	call_rcu(&f->rcu, fdb_rcu_free);
85 }
86 
87 void br_fdb_changeaddr(struct net_bridge_port *p, const unsigned char *newaddr)
88 {
89 	struct net_bridge *br = p->br;
90 	int i;
91 
92 	spin_lock_bh(&br->hash_lock);
93 
94 	/* Search all chains since old address/hash is unknown */
95 	for (i = 0; i < BR_HASH_SIZE; i++) {
96 		struct hlist_node *h;
97 		hlist_for_each(h, &br->hash[i]) {
98 			struct net_bridge_fdb_entry *f;
99 
100 			f = hlist_entry(h, struct net_bridge_fdb_entry, hlist);
101 			if (f->dst == p && f->is_local) {
102 				/* maybe another port has same hw addr? */
103 				struct net_bridge_port *op;
104 				list_for_each_entry(op, &br->port_list, list) {
105 					if (op != p &&
106 					    !compare_ether_addr(op->dev->dev_addr,
107 								f->addr.addr)) {
108 						f->dst = op;
109 						goto insert;
110 					}
111 				}
112 
113 				/* delete old one */
114 				fdb_delete(f);
115 				goto insert;
116 			}
117 		}
118 	}
119  insert:
120 	/* insert new address,  may fail if invalid address or dup. */
121 	fdb_insert(br, p, newaddr);
122 
123 	spin_unlock_bh(&br->hash_lock);
124 }
125 
126 void br_fdb_cleanup(unsigned long _data)
127 {
128 	struct net_bridge *br = (struct net_bridge *)_data;
129 	unsigned long delay = hold_time(br);
130 	unsigned long next_timer = jiffies + br->forward_delay;
131 	int i;
132 
133 	spin_lock_bh(&br->hash_lock);
134 	for (i = 0; i < BR_HASH_SIZE; i++) {
135 		struct net_bridge_fdb_entry *f;
136 		struct hlist_node *h, *n;
137 
138 		hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
139 			unsigned long this_timer;
140 			if (f->is_static)
141 				continue;
142 			this_timer = f->ageing_timer + delay;
143 			if (time_before_eq(this_timer, jiffies))
144 				fdb_delete(f);
145 			else if (time_before(this_timer, next_timer))
146 				next_timer = this_timer;
147 		}
148 	}
149 	spin_unlock_bh(&br->hash_lock);
150 
151 	/* Add HZ/4 to ensure we round the jiffies upwards to be after the next
152 	 * timer, otherwise we might round down and will have no-op run. */
153 	mod_timer(&br->gc_timer, round_jiffies(next_timer + HZ/4));
154 }
155 
156 /* Completely flush all dynamic entries in forwarding database.*/
157 void br_fdb_flush(struct net_bridge *br)
158 {
159 	int i;
160 
161 	spin_lock_bh(&br->hash_lock);
162 	for (i = 0; i < BR_HASH_SIZE; i++) {
163 		struct net_bridge_fdb_entry *f;
164 		struct hlist_node *h, *n;
165 		hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
166 			if (!f->is_static)
167 				fdb_delete(f);
168 		}
169 	}
170 	spin_unlock_bh(&br->hash_lock);
171 }
172 
173 /* Flush all entries refering to a specific port.
174  * if do_all is set also flush static entries
175  */
176 void br_fdb_delete_by_port(struct net_bridge *br,
177 			   const struct net_bridge_port *p,
178 			   int do_all)
179 {
180 	int i;
181 
182 	spin_lock_bh(&br->hash_lock);
183 	for (i = 0; i < BR_HASH_SIZE; i++) {
184 		struct hlist_node *h, *g;
185 
186 		hlist_for_each_safe(h, g, &br->hash[i]) {
187 			struct net_bridge_fdb_entry *f
188 				= hlist_entry(h, struct net_bridge_fdb_entry, hlist);
189 			if (f->dst != p)
190 				continue;
191 
192 			if (f->is_static && !do_all)
193 				continue;
194 			/*
195 			 * if multiple ports all have the same device address
196 			 * then when one port is deleted, assign
197 			 * the local entry to other port
198 			 */
199 			if (f->is_local) {
200 				struct net_bridge_port *op;
201 				list_for_each_entry(op, &br->port_list, list) {
202 					if (op != p &&
203 					    !compare_ether_addr(op->dev->dev_addr,
204 								f->addr.addr)) {
205 						f->dst = op;
206 						goto skip_delete;
207 					}
208 				}
209 			}
210 
211 			fdb_delete(f);
212 		skip_delete: ;
213 		}
214 	}
215 	spin_unlock_bh(&br->hash_lock);
216 }
217 
218 /* No locking or refcounting, assumes caller has no preempt (rcu_read_lock) */
219 struct net_bridge_fdb_entry *__br_fdb_get(struct net_bridge *br,
220 					  const unsigned char *addr)
221 {
222 	struct hlist_node *h;
223 	struct net_bridge_fdb_entry *fdb;
224 
225 	hlist_for_each_entry_rcu(fdb, h, &br->hash[br_mac_hash(addr)], hlist) {
226 		if (!compare_ether_addr(fdb->addr.addr, addr)) {
227 			if (unlikely(has_expired(br, fdb)))
228 				break;
229 			return fdb;
230 		}
231 	}
232 
233 	return NULL;
234 }
235 
236 #if defined(CONFIG_ATM_LANE) || defined(CONFIG_ATM_LANE_MODULE)
237 /* Interface used by ATM LANE hook to test
238  * if an addr is on some other bridge port */
239 int br_fdb_test_addr(struct net_device *dev, unsigned char *addr)
240 {
241 	struct net_bridge_fdb_entry *fdb;
242 	int ret;
243 
244 	if (!dev->br_port)
245 		return 0;
246 
247 	rcu_read_lock();
248 	fdb = __br_fdb_get(dev->br_port->br, addr);
249 	ret = fdb && fdb->dst->dev != dev &&
250 		fdb->dst->state == BR_STATE_FORWARDING;
251 	rcu_read_unlock();
252 
253 	return ret;
254 }
255 #endif /* CONFIG_ATM_LANE */
256 
257 /*
258  * Fill buffer with forwarding table records in
259  * the API format.
260  */
261 int br_fdb_fillbuf(struct net_bridge *br, void *buf,
262 		   unsigned long maxnum, unsigned long skip)
263 {
264 	struct __fdb_entry *fe = buf;
265 	int i, num = 0;
266 	struct hlist_node *h;
267 	struct net_bridge_fdb_entry *f;
268 
269 	memset(buf, 0, maxnum*sizeof(struct __fdb_entry));
270 
271 	rcu_read_lock();
272 	for (i = 0; i < BR_HASH_SIZE; i++) {
273 		hlist_for_each_entry_rcu(f, h, &br->hash[i], hlist) {
274 			if (num >= maxnum)
275 				goto out;
276 
277 			if (has_expired(br, f))
278 				continue;
279 
280 			if (skip) {
281 				--skip;
282 				continue;
283 			}
284 
285 			/* convert from internal format to API */
286 			memcpy(fe->mac_addr, f->addr.addr, ETH_ALEN);
287 
288 			/* due to ABI compat need to split into hi/lo */
289 			fe->port_no = f->dst->port_no;
290 			fe->port_hi = f->dst->port_no >> 8;
291 
292 			fe->is_local = f->is_local;
293 			if (!f->is_static)
294 				fe->ageing_timer_value = jiffies_to_clock_t(jiffies - f->ageing_timer);
295 			++fe;
296 			++num;
297 		}
298 	}
299 
300  out:
301 	rcu_read_unlock();
302 
303 	return num;
304 }
305 
306 static inline struct net_bridge_fdb_entry *fdb_find(struct hlist_head *head,
307 						    const unsigned char *addr)
308 {
309 	struct hlist_node *h;
310 	struct net_bridge_fdb_entry *fdb;
311 
312 	hlist_for_each_entry_rcu(fdb, h, head, hlist) {
313 		if (!compare_ether_addr(fdb->addr.addr, addr))
314 			return fdb;
315 	}
316 	return NULL;
317 }
318 
319 static struct net_bridge_fdb_entry *fdb_create(struct hlist_head *head,
320 					       struct net_bridge_port *source,
321 					       const unsigned char *addr,
322 					       int is_local)
323 {
324 	struct net_bridge_fdb_entry *fdb;
325 
326 	fdb = kmem_cache_alloc(br_fdb_cache, GFP_ATOMIC);
327 	if (fdb) {
328 		memcpy(fdb->addr.addr, addr, ETH_ALEN);
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 
339 static 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 
368 int 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 
379 void 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