netfilter: ebtables: only call xt_compat_add_offset once per rule
[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  *      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
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);
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 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 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
82 static 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
88 void 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
127 void 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->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         mod_timer(&br->gc_timer, round_jiffies_up(next_timer));
153 }
154
155 /* Completely flush all dynamic entries in forwarding database.*/
156 void 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  */
175 void 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 */
218 struct 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 */
238 int 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  */
263 int 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->ageing_timer);
297                         ++fe;
298                         ++num;
299                 }
300         }
301
302  out:
303         rcu_read_unlock();
304
305         return num;
306 }
307
308 static inline 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_rcu(fdb, h, head, hlist) {
315                 if (!compare_ether_addr(fdb->addr.addr, addr))
316                         return fdb;
317         }
318         return NULL;
319 }
320
321 static struct net_bridge_fdb_entry *fdb_create(struct hlist_head *head,
322                                                struct net_bridge_port *source,
323                                                const unsigned char *addr,
324                                                int is_local)
325 {
326         struct net_bridge_fdb_entry *fdb;
327
328         fdb = kmem_cache_alloc(br_fdb_cache, GFP_ATOMIC);
329         if (fdb) {
330                 memcpy(fdb->addr.addr, addr, ETH_ALEN);
331                 fdb->dst = source;
332                 fdb->is_local = is_local;
333                 fdb->is_static = is_local;
334                 fdb->ageing_timer = jiffies;
335
336                 hlist_add_head_rcu(&fdb->hlist, head);
337         }
338         return fdb;
339 }
340
341 static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
342                   const unsigned char *addr)
343 {
344         struct hlist_head *head = &br->hash[br_mac_hash(addr)];
345         struct net_bridge_fdb_entry *fdb;
346
347         if (!is_valid_ether_addr(addr))
348                 return -EINVAL;
349
350         fdb = fdb_find(head, addr);
351         if (fdb) {
352                 /* it is okay to have multiple ports with same
353                  * address, just use the first one.
354                  */
355                 if (fdb->is_local)
356                         return 0;
357                 br_warn(br, "adding interface %s with same address "
358                        "as a received packet\n",
359                        source->dev->name);
360                 fdb_delete(fdb);
361         }
362
363         if (!fdb_create(head, source, addr, 1))
364                 return -ENOMEM;
365
366         return 0;
367 }
368
369 int br_fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
370                   const unsigned char *addr)
371 {
372         int ret;
373
374         spin_lock_bh(&br->hash_lock);
375         ret = fdb_insert(br, source, addr);
376         spin_unlock_bh(&br->hash_lock);
377         return ret;
378 }
379
380 void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
381                    const unsigned char *addr)
382 {
383         struct hlist_head *head = &br->hash[br_mac_hash(addr)];
384         struct net_bridge_fdb_entry *fdb;
385
386         /* some users want to always flood. */
387         if (hold_time(br) == 0)
388                 return;
389
390         /* ignore packets unless we are using this port */
391         if (!(source->state == BR_STATE_LEARNING ||
392               source->state == BR_STATE_FORWARDING))
393                 return;
394
395         fdb = fdb_find(head, addr);
396         if (likely(fdb)) {
397                 /* attempt to update an entry for a local interface */
398                 if (unlikely(fdb->is_local)) {
399                         if (net_ratelimit())
400                                 br_warn(br, "received packet on %s with "
401                                         "own address as source address\n",
402                                         source->dev->name);
403                 } else {
404                         /* fastpath: update of existing entry */
405                         fdb->dst = source;
406                         fdb->ageing_timer = jiffies;
407                 }
408         } else {
409                 spin_lock(&br->hash_lock);
410                 if (!fdb_find(head, addr))
411                         fdb_create(head, source, addr, 0);
412                 /* else  we lose race and someone else inserts
413                  * it first, don't bother updating
414                  */
415                 spin_unlock(&br->hash_lock);
416         }
417 }