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);
  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 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 (time_before(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
 289                         /* due to ABI compat need to split into hi/lo */
 290                         fe->port_no = f->dst->port_no;
 291                         fe->port_hi = f->dst->port_no >> 8;
 292
 293                         fe->is_local = f->is_local;
 294                         if (!f->is_static)
 295                                 fe->ageing_timer_value = jiffies_to_clock_t(jiffies - f->ageing_timer);
 296                         ++fe;
 297                         ++num;
 298                 }
 299         }
 300
 301  out:
 302         rcu_read_unlock();
 303
 304         return num;
 305 }
 306
 307 static inline struct net_bridge_fdb_entry *fdb_find(struct hlist_head *head,
 308                                                     const unsigned char *addr)
 309 {
 310         struct hlist_node *h;
 311         struct net_bridge_fdb_entry *fdb;
 312
 313         hlist_for_each_entry_rcu(fdb, h, head, hlist) {
 314                 if (!compare_ether_addr(fdb->addr.addr, addr))
 315                         return fdb;
 316         }
 317         return NULL;
 318 }
 319
 320 static struct net_bridge_fdb_entry *fdb_create(struct hlist_head *head,
 321                                                struct net_bridge_port *source,
 322                                                const unsigned char *addr,
 323                                                int is_local)
 324 {
 325         struct net_bridge_fdb_entry *fdb;
 326
 327         fdb = kmem_cache_alloc(br_fdb_cache, GFP_ATOMIC);
 328         if (fdb) {
 329                 memcpy(fdb->addr.addr, addr, ETH_ALEN);
 330                 atomic_set(&fdb->use_count, 1);
 331                 hlist_add_head_rcu(&fdb->hlist, head);
 332
 333                 fdb->dst = source;
 334                 fdb->is_local = is_local;
 335                 fdb->is_static = is_local;
 336                 fdb->ageing_timer = jiffies;
 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
 358                 printk(KERN_WARNING "%s adding interface with same address "
 359                        "as a received packet\n",
 360                        source->dev->name);
 361                 fdb_delete(fdb);
 362         }
 363
 364         if (!fdb_create(head, source, addr, 1))
 365                 return -ENOMEM;
 366
 367         return 0;
 368 }
 369
 370 int br_fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
 371                   const unsigned char *addr)
 372 {
 373         int ret;
 374
 375         spin_lock_bh(&br->hash_lock);
 376         ret = fdb_insert(br, source, addr);
 377         spin_unlock_bh(&br->hash_lock);
 378         return ret;
 379 }
 380
 381 void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
 382                    const unsigned char *addr)
 383 {
 384         struct hlist_head *head = &br->hash[br_mac_hash(addr)];
 385         struct net_bridge_fdb_entry *fdb;
 386
 387         /* some users want to always flood. */
 388         if (hold_time(br) == 0)
 389                 return;
 390
 391         /* ignore packets unless we are using this port */
 392         if (!(source->state == BR_STATE_LEARNING ||
 393               source->state == BR_STATE_FORWARDING))
 394                 return;
 395
 396         fdb = fdb_find(head, addr);
 397         if (likely(fdb)) {
 398                 /* attempt to update an entry for a local interface */
 399                 if (unlikely(fdb->is_local)) {
 400                         if (net_ratelimit())
 401                                 printk(KERN_WARNING "%s: received packet with "
 402                                        " own address as source address\n",
 403                                        source->dev->name);
 404                 } else {
 405                         /* fastpath: update of existing entry */
 406                         fdb->dst = source;
 407                         fdb->ageing_timer = jiffies;
 408                 }
 409         } else {
 410                 spin_lock(&br->hash_lock);
 411                 if (!fdb_find(head, addr))
 412                         fdb_create(head, source, addr, 0);
 413                 /* else  we lose race and someone else inserts
 414                  * it first, don't bother updating
 415                  */
 416                 spin_unlock(&br->hash_lock);
 417         }
 418 }