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 <asm/atomic.h>
  24 #include "br_private.h"
  25
  26 static kmem_cache_t *br_fdb_cache __read_mostly;
  27 static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
  28                       const unsigned char *addr);
  29
  30 void __init br_fdb_init(void)
  31 {
  32         br_fdb_cache = kmem_cache_create("bridge_fdb_cache",
  33                                          sizeof(struct net_bridge_fdb_entry),
  34                                          0,
  35                                          SLAB_HWCACHE_ALIGN, NULL, NULL);
  36 }
  37
  38 void __exit br_fdb_fini(void)
  39 {
  40         kmem_cache_destroy(br_fdb_cache);
  41 }
  42
  43
  44 /* if topology_changing then use forward_delay (default 15 sec)
  45  * otherwise keep longer (default 5 minutes)
  46  */
  47 static __inline__ unsigned long hold_time(const struct net_bridge *br)
  48 {
  49         return br->topology_change ? br->forward_delay : br->ageing_time;
  50 }
  51
  52 static __inline__ int has_expired(const struct net_bridge *br,
  53                                   const struct net_bridge_fdb_entry *fdb)
  54 {
  55         return !fdb->is_static
  56                 && time_before_eq(fdb->ageing_timer + hold_time(br), jiffies);
  57 }
  58
  59 static __inline__ int br_mac_hash(const unsigned char *mac)
  60 {
  61         return jhash(mac, ETH_ALEN, 0) & (BR_HASH_SIZE - 1);
  62 }
  63
  64 static __inline__ void fdb_delete(struct net_bridge_fdb_entry *f)
  65 {
  66         hlist_del_rcu(&f->hlist);
  67         br_fdb_put(f);
  68 }
  69
  70 void br_fdb_changeaddr(struct net_bridge_port *p, const unsigned char *newaddr)
  71 {
  72         struct net_bridge *br = p->br;
  73         int i;
  74
  75         spin_lock_bh(&br->hash_lock);
  76
  77         /* Search all chains since old address/hash is unknown */
  78         for (i = 0; i < BR_HASH_SIZE; i++) {
  79                 struct hlist_node *h;
  80                 hlist_for_each(h, &br->hash[i]) {
  81                         struct net_bridge_fdb_entry *f;
  82
  83                         f = hlist_entry(h, struct net_bridge_fdb_entry, hlist);
  84                         if (f->dst == p && f->is_local) {
  85                                 /* maybe another port has same hw addr? */
  86                                 struct net_bridge_port *op;
  87                                 list_for_each_entry(op, &br->port_list, list) {
  88                                         if (op != p &&
  89                                             !compare_ether_addr(op->dev->dev_addr,
  90                                                                 f->addr.addr)) {
  91                                                 f->dst = op;
  92                                                 goto insert;
  93                                         }
  94                                 }
  95
  96                                 /* delete old one */
  97                                 fdb_delete(f);
  98                                 goto insert;
  99                         }
 100                 }
 101         }
 102  insert:
 103         /* insert new address,  may fail if invalid address or dup. */
 104         fdb_insert(br, p, newaddr);
 105
 106         spin_unlock_bh(&br->hash_lock);
 107 }
 108
 109 void br_fdb_cleanup(unsigned long _data)
 110 {
 111         struct net_bridge *br = (struct net_bridge *)_data;
 112         unsigned long delay = hold_time(br);
 113         int i;
 114
 115         spin_lock_bh(&br->hash_lock);
 116         for (i = 0; i < BR_HASH_SIZE; i++) {
 117                 struct net_bridge_fdb_entry *f;
 118                 struct hlist_node *h, *n;
 119
 120                 hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
 121                         if (!f->is_static &&
 122                             time_before_eq(f->ageing_timer + delay, jiffies))
 123                                 fdb_delete(f);
 124                 }
 125         }
 126         spin_unlock_bh(&br->hash_lock);
 127
 128         mod_timer(&br->gc_timer, jiffies + HZ/10);
 129 }
 130
 131 void br_fdb_delete_by_port(struct net_bridge *br, struct net_bridge_port *p)
 132 {
 133         int i;
 134
 135         spin_lock_bh(&br->hash_lock);
 136         for (i = 0; i < BR_HASH_SIZE; i++) {
 137                 struct hlist_node *h, *g;
 138
 139                 hlist_for_each_safe(h, g, &br->hash[i]) {
 140                         struct net_bridge_fdb_entry *f
 141                                 = hlist_entry(h, struct net_bridge_fdb_entry, hlist);
 142                         if (f->dst != p)
 143                                 continue;
 144
 145                         /*
 146                          * if multiple ports all have the same device address
 147                          * then when one port is deleted, assign
 148                          * the local entry to other port
 149                          */
 150                         if (f->is_local) {
 151                                 struct net_bridge_port *op;
 152                                 list_for_each_entry(op, &br->port_list, list) {
 153                                         if (op != p &&
 154                                             !compare_ether_addr(op->dev->dev_addr,
 155                                                                 f->addr.addr)) {
 156                                                 f->dst = op;
 157                                                 goto skip_delete;
 158                                         }
 159                                 }
 160                         }
 161
 162                         fdb_delete(f);
 163                 skip_delete: ;
 164                 }
 165         }
 166         spin_unlock_bh(&br->hash_lock);
 167 }
 168
 169 /* No locking or refcounting, assumes caller has no preempt (rcu_read_lock) */
 170 struct net_bridge_fdb_entry *__br_fdb_get(struct net_bridge *br,
 171                                           const unsigned char *addr)
 172 {
 173         struct hlist_node *h;
 174         struct net_bridge_fdb_entry *fdb;
 175
 176         hlist_for_each_entry_rcu(fdb, h, &br->hash[br_mac_hash(addr)], hlist) {
 177                 if (!compare_ether_addr(fdb->addr.addr, addr)) {
 178                         if (unlikely(has_expired(br, fdb)))
 179                                 break;
 180                         return fdb;
 181                 }
 182         }
 183
 184         return NULL;
 185 }
 186
 187 /* Interface used by ATM hook that keeps a ref count */
 188 struct net_bridge_fdb_entry *br_fdb_get(struct net_bridge *br,
 189                                         unsigned char *addr)
 190 {
 191         struct net_bridge_fdb_entry *fdb;
 192
 193         rcu_read_lock();
 194         fdb = __br_fdb_get(br, addr);
 195         if (fdb)
 196                 atomic_inc(&fdb->use_count);
 197         rcu_read_unlock();
 198         return fdb;
 199 }
 200
 201 static void fdb_rcu_free(struct rcu_head *head)
 202 {
 203         struct net_bridge_fdb_entry *ent
 204                 = container_of(head, struct net_bridge_fdb_entry, rcu);
 205         kmem_cache_free(br_fdb_cache, ent);
 206 }
 207
 208 /* Set entry up for deletion with RCU  */
 209 void br_fdb_put(struct net_bridge_fdb_entry *ent)
 210 {
 211         if (atomic_dec_and_test(&ent->use_count))
 212                 call_rcu(&ent->rcu, fdb_rcu_free);
 213 }
 214
 215 /*
 216  * Fill buffer with forwarding table records in
 217  * the API format.
 218  */
 219 int br_fdb_fillbuf(struct net_bridge *br, void *buf,
 220                    unsigned long maxnum, unsigned long skip)
 221 {
 222         struct __fdb_entry *fe = buf;
 223         int i, num = 0;
 224         struct hlist_node *h;
 225         struct net_bridge_fdb_entry *f;
 226
 227         memset(buf, 0, maxnum*sizeof(struct __fdb_entry));
 228
 229         rcu_read_lock();
 230         for (i = 0; i < BR_HASH_SIZE; i++) {
 231                 hlist_for_each_entry_rcu(f, h, &br->hash[i], hlist) {
 232                         if (num >= maxnum)
 233                                 goto out;
 234
 235                         if (has_expired(br, f))
 236                                 continue;
 237
 238                         if (skip) {
 239                                 --skip;
 240                                 continue;
 241                         }
 242
 243                         /* convert from internal format to API */
 244                         memcpy(fe->mac_addr, f->addr.addr, ETH_ALEN);
 245                         fe->port_no = f->dst->port_no;
 246                         fe->is_local = f->is_local;
 247                         if (!f->is_static)
 248                                 fe->ageing_timer_value = jiffies_to_clock_t(jiffies - f->ageing_timer);
 249                         ++fe;
 250                         ++num;
 251                 }
 252         }
 253
 254  out:
 255         rcu_read_unlock();
 256
 257         return num;
 258 }
 259
 260 static inline struct net_bridge_fdb_entry *fdb_find(struct hlist_head *head,
 261                                                     const unsigned char *addr)
 262 {
 263         struct hlist_node *h;
 264         struct net_bridge_fdb_entry *fdb;
 265
 266         hlist_for_each_entry_rcu(fdb, h, head, hlist) {
 267                 if (!compare_ether_addr(fdb->addr.addr, addr))
 268                         return fdb;
 269         }
 270         return NULL;
 271 }
 272
 273 static struct net_bridge_fdb_entry *fdb_create(struct hlist_head *head,
 274                                                struct net_bridge_port *source,
 275                                                const unsigned char *addr,
 276                                                int is_local)
 277 {
 278         struct net_bridge_fdb_entry *fdb;
 279
 280         fdb = kmem_cache_alloc(br_fdb_cache, GFP_ATOMIC);
 281         if (fdb) {
 282                 memcpy(fdb->addr.addr, addr, ETH_ALEN);
 283                 atomic_set(&fdb->use_count, 1);
 284                 hlist_add_head_rcu(&fdb->hlist, head);
 285
 286                 fdb->dst = source;
 287                 fdb->is_local = is_local;
 288                 fdb->is_static = is_local;
 289                 fdb->ageing_timer = jiffies;
 290         }
 291         return fdb;
 292 }
 293
 294 static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
 295                   const unsigned char *addr)
 296 {
 297         struct hlist_head *head = &br->hash[br_mac_hash(addr)];
 298         struct net_bridge_fdb_entry *fdb;
 299
 300         if (!is_valid_ether_addr(addr))
 301                 return -EINVAL;
 302
 303         fdb = fdb_find(head, addr);
 304         if (fdb) {
 305                 /* it is okay to have multiple ports with same
 306                  * address, just use the first one.
 307                  */
 308                 if (fdb->is_local)
 309                         return 0;
 310
 311                 printk(KERN_WARNING "%s adding interface with same address "
 312                        "as a received packet\n",
 313                        source->dev->name);
 314                 fdb_delete(fdb);
 315         }
 316
 317         if (!fdb_create(head, source, addr, 1))
 318                 return -ENOMEM;
 319
 320         return 0;
 321 }
 322
 323 int br_fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
 324                   const unsigned char *addr)
 325 {
 326         int ret;
 327
 328         spin_lock_bh(&br->hash_lock);
 329         ret = fdb_insert(br, source, addr);
 330         spin_unlock_bh(&br->hash_lock);
 331         return ret;
 332 }
 333
 334 void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
 335                    const unsigned char *addr)
 336 {
 337         struct hlist_head *head = &br->hash[br_mac_hash(addr)];
 338         struct net_bridge_fdb_entry *fdb;
 339
 340         /* some users want to always flood. */
 341         if (hold_time(br) == 0)
 342                 return;
 343
 344         rcu_read_lock();
 345         fdb = fdb_find(head, addr);
 346         if (likely(fdb)) {
 347                 /* attempt to update an entry for a local interface */
 348                 if (unlikely(fdb->is_local)) {
 349                         if (net_ratelimit())
 350                                 printk(KERN_WARNING "%s: received packet with "
 351                                        " own address as source address\n",
 352                                        source->dev->name);
 353                 } else {
 354                         /* fastpath: update of existing entry */
 355                         fdb->dst = source;
 356                         fdb->ageing_timer = jiffies;
 357                 }
 358         } else {
 359                 spin_lock_bh(&br->hash_lock);
 360                 if (!fdb_find(head, addr))
 361                         fdb_create(head, source, addr, 0);
 362                 /* else  we lose race and someone else inserts
 363                  * it first, don't bother updating
 364                  */
 365                 spin_unlock_bh(&br->hash_lock);
 366         }
 367         rcu_read_unlock();
 368 }