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 void __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         get_random_bytes(&fdb_salt, sizeof(fdb_salt));
  41 }
  42
  43 void __exit br_fdb_fini(void)
  44 {
  45         kmem_cache_destroy(br_fdb_cache);
  46 }
  47
  48
  49 /* if topology_changing then use forward_delay (default 15 sec)
  50  * otherwise keep longer (default 5 minutes)
  51  */
  52 static inline unsigned long hold_time(const struct net_bridge *br)
  53 {
  54         return br->topology_change ? br->forward_delay : br->ageing_time;
  55 }
  56
  57 static inline int has_expired(const struct net_bridge *br,
  58                                   const struct net_bridge_fdb_entry *fdb)
  59 {
  60         return !fdb->is_static
  61                 && time_before_eq(fdb->ageing_timer + hold_time(br), jiffies);
  62 }
  63
  64 static inline int br_mac_hash(const unsigned char *mac)
  65 {
  66         /* use 1 byte of OUI cnd 3 bytes of NIC */
  67         u32 key = get_unaligned((u32 *)(mac + 2));
  68         return jhash_1word(key, fdb_salt) & (BR_HASH_SIZE - 1);
  69 }
  70
  71 static inline void fdb_delete(struct net_bridge_fdb_entry *f)
  72 {
  73         hlist_del_rcu(&f->hlist);
  74         br_fdb_put(f);
  75 }
  76
  77 void br_fdb_changeaddr(struct net_bridge_port *p, const unsigned char *newaddr)
  78 {
  79         struct net_bridge *br = p->br;
  80         int i;
  81
  82         spin_lock_bh(&br->hash_lock);
  83
  84         /* Search all chains since old address/hash is unknown */
  85         for (i = 0; i < BR_HASH_SIZE; i++) {
  86                 struct hlist_node *h;
  87                 hlist_for_each(h, &br->hash[i]) {
  88                         struct net_bridge_fdb_entry *f;
  89
  90                         f = hlist_entry(h, struct net_bridge_fdb_entry, hlist);
  91                         if (f->dst == p && f->is_local) {
  92                                 /* maybe another port has same hw addr? */
  93                                 struct net_bridge_port *op;
  94                                 list_for_each_entry(op, &br->port_list, list) {
  95                                         if (op != p &&
  96                                             !compare_ether_addr(op->dev->dev_addr,
  97                                                                 f->addr.addr)) {
  98                                                 f->dst = op;
  99                                                 goto insert;
 100                                         }
 101                                 }
 102
 103                                 /* delete old one */
 104                                 fdb_delete(f);
 105                                 goto insert;
 106                         }
 107                 }
 108         }
 109  insert:
 110         /* insert new address,  may fail if invalid address or dup. */
 111         fdb_insert(br, p, newaddr);
 112
 113         spin_unlock_bh(&br->hash_lock);
 114 }
 115
 116 void br_fdb_cleanup(unsigned long _data)
 117 {
 118         struct net_bridge *br = (struct net_bridge *)_data;
 119         unsigned long delay = hold_time(br);
 120         int i;
 121
 122         spin_lock_bh(&br->hash_lock);
 123         for (i = 0; i < BR_HASH_SIZE; i++) {
 124                 struct net_bridge_fdb_entry *f;
 125                 struct hlist_node *h, *n;
 126
 127                 hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
 128                         if (!f->is_static &&
 129                             time_before_eq(f->ageing_timer + delay, jiffies))
 130                                 fdb_delete(f);
 131                 }
 132         }
 133         spin_unlock_bh(&br->hash_lock);
 134
 135         mod_timer(&br->gc_timer, jiffies + HZ/10);
 136 }
 137
 138 /* Completely flush all dynamic entries in forwarding database.*/
 139 void br_fdb_flush(struct net_bridge *br)
 140 {
 141         int i;
 142
 143         spin_lock_bh(&br->hash_lock);
 144         for (i = 0; i < BR_HASH_SIZE; i++) {
 145                 struct net_bridge_fdb_entry *f;
 146                 struct hlist_node *h, *n;
 147                 hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
 148                         if (!f->is_static)
 149                                 fdb_delete(f);
 150                 }
 151         }
 152         spin_unlock_bh(&br->hash_lock);
 153 }
 154
 155 /* Flush all entries refering to a specific port.
 156  * if do_all is set also flush static entries
 157  */
 158 void br_fdb_delete_by_port(struct net_bridge *br,
 159                            const struct net_bridge_port *p,
 160                            int do_all)
 161 {
 162         int i;
 163
 164         spin_lock_bh(&br->hash_lock);
 165         for (i = 0; i < BR_HASH_SIZE; i++) {
 166                 struct hlist_node *h, *g;
 167
 168                 hlist_for_each_safe(h, g, &br->hash[i]) {
 169                         struct net_bridge_fdb_entry *f
 170                                 = hlist_entry(h, struct net_bridge_fdb_entry, hlist);
 171                         if (f->dst != p)
 172                                 continue;
 173
 174                         if (f->is_static && !do_all)
 175                                 continue;
 176                         /*
 177                          * if multiple ports all have the same device address
 178                          * then when one port is deleted, assign
 179                          * the local entry to other port
 180                          */
 181                         if (f->is_local) {
 182                                 struct net_bridge_port *op;
 183                                 list_for_each_entry(op, &br->port_list, list) {
 184                                         if (op != p &&
 185                                             !compare_ether_addr(op->dev->dev_addr,
 186                                                                 f->addr.addr)) {
 187                                                 f->dst = op;
 188                                                 goto skip_delete;
 189                                         }
 190                                 }
 191                         }
 192
 193                         fdb_delete(f);
 194                 skip_delete: ;
 195                 }
 196         }
 197         spin_unlock_bh(&br->hash_lock);
 198 }
 199
 200 /* No locking or refcounting, assumes caller has no preempt (rcu_read_lock) */
 201 struct net_bridge_fdb_entry *__br_fdb_get(struct net_bridge *br,
 202                                           const unsigned char *addr)
 203 {
 204         struct hlist_node *h;
 205         struct net_bridge_fdb_entry *fdb;
 206
 207         hlist_for_each_entry_rcu(fdb, h, &br->hash[br_mac_hash(addr)], hlist) {
 208                 if (!compare_ether_addr(fdb->addr.addr, addr)) {
 209                         if (unlikely(has_expired(br, fdb)))
 210                                 break;
 211                         return fdb;
 212                 }
 213         }
 214
 215         return NULL;
 216 }
 217
 218 /* Interface used by ATM hook that keeps a ref count */
 219 struct net_bridge_fdb_entry *br_fdb_get(struct net_bridge *br,
 220                                         unsigned char *addr)
 221 {
 222         struct net_bridge_fdb_entry *fdb;
 223
 224         rcu_read_lock();
 225         fdb = __br_fdb_get(br, addr);
 226         if (fdb && !atomic_inc_not_zero(&fdb->use_count))
 227                 fdb = NULL;
 228         rcu_read_unlock();
 229         return fdb;
 230 }
 231
 232 static void fdb_rcu_free(struct rcu_head *head)
 233 {
 234         struct net_bridge_fdb_entry *ent
 235                 = container_of(head, struct net_bridge_fdb_entry, rcu);
 236         kmem_cache_free(br_fdb_cache, ent);
 237 }
 238
 239 /* Set entry up for deletion with RCU  */
 240 void br_fdb_put(struct net_bridge_fdb_entry *ent)
 241 {
 242         if (atomic_dec_and_test(&ent->use_count))
 243                 call_rcu(&ent->rcu, fdb_rcu_free);
 244 }
 245
 246 /*
 247  * Fill buffer with forwarding table records in
 248  * the API format.
 249  */
 250 int br_fdb_fillbuf(struct net_bridge *br, void *buf,
 251                    unsigned long maxnum, unsigned long skip)
 252 {
 253         struct __fdb_entry *fe = buf;
 254         int i, num = 0;
 255         struct hlist_node *h;
 256         struct net_bridge_fdb_entry *f;
 257
 258         memset(buf, 0, maxnum*sizeof(struct __fdb_entry));
 259
 260         rcu_read_lock();
 261         for (i = 0; i < BR_HASH_SIZE; i++) {
 262                 hlist_for_each_entry_rcu(f, h, &br->hash[i], hlist) {
 263                         if (num >= maxnum)
 264                                 goto out;
 265
 266                         if (has_expired(br, f))
 267                                 continue;
 268
 269                         if (skip) {
 270                                 --skip;
 271                                 continue;
 272                         }
 273
 274                         /* convert from internal format to API */
 275                         memcpy(fe->mac_addr, f->addr.addr, ETH_ALEN);
 276                         fe->port_no = f->dst->port_no;
 277                         fe->is_local = f->is_local;
 278                         if (!f->is_static)
 279                                 fe->ageing_timer_value = jiffies_to_clock_t(jiffies - f->ageing_timer);
 280                         ++fe;
 281                         ++num;
 282                 }
 283         }
 284
 285  out:
 286         rcu_read_unlock();
 287
 288         return num;
 289 }
 290
 291 static inline struct net_bridge_fdb_entry *fdb_find(struct hlist_head *head,
 292                                                     const unsigned char *addr)
 293 {
 294         struct hlist_node *h;
 295         struct net_bridge_fdb_entry *fdb;
 296
 297         hlist_for_each_entry_rcu(fdb, h, head, hlist) {
 298                 if (!compare_ether_addr(fdb->addr.addr, addr))
 299                         return fdb;
 300         }
 301         return NULL;
 302 }
 303
 304 static struct net_bridge_fdb_entry *fdb_create(struct hlist_head *head,
 305                                                struct net_bridge_port *source,
 306                                                const unsigned char *addr,
 307                                                int is_local)
 308 {
 309         struct net_bridge_fdb_entry *fdb;
 310
 311         fdb = kmem_cache_alloc(br_fdb_cache, GFP_ATOMIC);
 312         if (fdb) {
 313                 memcpy(fdb->addr.addr, addr, ETH_ALEN);
 314                 atomic_set(&fdb->use_count, 1);
 315                 hlist_add_head_rcu(&fdb->hlist, head);
 316
 317                 fdb->dst = source;
 318                 fdb->is_local = is_local;
 319                 fdb->is_static = is_local;
 320                 fdb->ageing_timer = jiffies;
 321         }
 322         return fdb;
 323 }
 324
 325 static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
 326                   const unsigned char *addr)
 327 {
 328         struct hlist_head *head = &br->hash[br_mac_hash(addr)];
 329         struct net_bridge_fdb_entry *fdb;
 330
 331         if (!is_valid_ether_addr(addr))
 332                 return -EINVAL;
 333
 334         fdb = fdb_find(head, addr);
 335         if (fdb) {
 336                 /* it is okay to have multiple ports with same
 337                  * address, just use the first one.
 338                  */
 339                 if (fdb->is_local)
 340                         return 0;
 341
 342                 printk(KERN_WARNING "%s adding interface with same address "
 343                        "as a received packet\n",
 344                        source->dev->name);
 345                 fdb_delete(fdb);
 346         }
 347
 348         if (!fdb_create(head, source, addr, 1))
 349                 return -ENOMEM;
 350
 351         return 0;
 352 }
 353
 354 int br_fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
 355                   const unsigned char *addr)
 356 {
 357         int ret;
 358
 359         spin_lock_bh(&br->hash_lock);
 360         ret = fdb_insert(br, source, addr);
 361         spin_unlock_bh(&br->hash_lock);
 362         return ret;
 363 }
 364
 365 void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
 366                    const unsigned char *addr)
 367 {
 368         struct hlist_head *head = &br->hash[br_mac_hash(addr)];
 369         struct net_bridge_fdb_entry *fdb;
 370
 371         /* some users want to always flood. */
 372         if (hold_time(br) == 0)
 373                 return;
 374
 375         fdb = fdb_find(head, addr);
 376         if (likely(fdb)) {
 377                 /* attempt to update an entry for a local interface */
 378                 if (unlikely(fdb->is_local)) {
 379                         if (net_ratelimit())
 380                                 printk(KERN_WARNING "%s: received packet with "
 381                                        " own address as source address\n",
 382                                        source->dev->name);
 383                 } else {
 384                         /* fastpath: update of existing entry */
 385                         fdb->dst = source;
 386                         fdb->ageing_timer = jiffies;
 387                 }
 388         } else {
 389                 spin_lock(&br->hash_lock);
 390                 if (!fdb_find(head, addr))
 391                         fdb_create(head, source, addr, 0);
 392                 /* else  we lose race and someone else inserts
 393                  * it first, don't bother updating
 394                  */
 395                 spin_unlock(&br->hash_lock);
 396         }
 397 }