Root/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
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->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.*/
156void 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 referring to a specific port.
173 * if do_all is set also flush static entries
174 */
175void 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 */
218struct 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 */
238int 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 */
263int 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
308static 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
321static 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
341static 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
369int 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
380void 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}
418

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