3fc697293819524823ee8bb4d9918493f12db6e0
[linux-2.6.git] / net / bridge / br_fdb.c
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
28 static struct kmem_cache *br_fdb_cache __read_mostly;
29 static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
30                       const unsigned char *addr);
31
32 static u32 fdb_salt __read_mostly;
33
34 int __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, NULL);
40         if (!br_fdb_cache)
41                 return -ENOMEM;
42
43         get_random_bytes(&fdb_salt, sizeof(fdb_salt));
44         return 0;
45 }
46
47 void __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  */
56 static inline unsigned long hold_time(const struct net_bridge *br)
57 {
58         return br->topology_change ? br->forward_delay : br->ageing_time;
59 }
60
61 static 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
68 static 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
75 static inline void fdb_delete(struct net_bridge_fdb_entry *f)
76 {
77         hlist_del_rcu(&f->hlist);
78         br_fdb_put(f);
79 }
80
81 void 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
120 void 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.*/
151 void 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  */
170 void 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) */
213 struct 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 */
231 struct 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
244 static 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  */
252 void 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  */
262 int 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
303 static 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
316 static 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
337 static 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
366 int 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
377 void 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         fdb = fdb_find(head, addr);
388         if (likely(fdb)) {
389                 /* attempt to update an entry for a local interface */
390                 if (unlikely(fdb->is_local)) {
391                         if (net_ratelimit())
392                                 printk(KERN_WARNING "%s: received packet with "
393                                        " own address as source address\n",
394                                        source->dev->name);
395                 } else {
396                         /* fastpath: update of existing entry */
397                         fdb->dst = source;
398                         fdb->ageing_timer = jiffies;
399                 }
400         } else {
401                 spin_lock(&br->hash_lock);
402                 if (!fdb_find(head, addr))
403                         fdb_create(head, source, addr, 0);
404                 /* else  we lose race and someone else inserts
405                  * it first, don't bother updating
406                  */
407                 spin_unlock(&br->hash_lock);
408         }
409 }