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 struct kmem_cache *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
 132 void br_fdb_delete_by_port(struct net_bridge *br,
 133                            const struct net_bridge_port *p,
 134                            int do_all)
 135 {
 136         int i;
 137
 138         spin_lock_bh(&br->hash_lock);
 139         for (i = 0; i < BR_HASH_SIZE; i++) {
 140                 struct hlist_node *h, *g;
 141
 142                 hlist_for_each_safe(h, g, &br->hash[i]) {
 143                         struct net_bridge_fdb_entry *f
 144                                 = hlist_entry(h, struct net_bridge_fdb_entry, hlist);
 145                         if (f->dst != p)
 146                                 continue;
 147
 148                         if (f->is_static && !do_all)
 149                                 continue;
 150                         /*
 151                          * if multiple ports all have the same device address
 152                          * then when one port is deleted, assign
 153                          * the local entry to other port
 154                          */
 155                         if (f->is_local) {
 156                                 struct net_bridge_port *op;
 157                                 list_for_each_entry(op, &br->port_list, list) {
 158                                         if (op != p &&
 159                                             !compare_ether_addr(op->dev->dev_addr,
 160                                                                 f->addr.addr)) {
 161                                                 f->dst = op;
 162                                                 goto skip_delete;
 163                                         }
 164                                 }
 165                         }
 166
 167                         fdb_delete(f);
 168                 skip_delete: ;
 169                 }
 170         }
 171         spin_unlock_bh(&br->hash_lock);
 172 }
 173
 174 /* No locking or refcounting, assumes caller has no preempt (rcu_read_lock) */
 175 struct net_bridge_fdb_entry *__br_fdb_get(struct net_bridge *br,
 176                                           const unsigned char *addr)
 177 {
 178         struct hlist_node *h;
 179         struct net_bridge_fdb_entry *fdb;
 180
 181         hlist_for_each_entry_rcu(fdb, h, &br->hash[br_mac_hash(addr)], hlist) {
 182                 if (!compare_ether_addr(fdb->addr.addr, addr)) {
 183                         if (unlikely(has_expired(br, fdb)))
 184                                 break;
 185                         return fdb;
 186                 }
 187         }
 188
 189         return NULL;
 190 }
 191
 192 /* Interface used by ATM hook that keeps a ref count */
 193 struct net_bridge_fdb_entry *br_fdb_get(struct net_bridge *br,
 194                                         unsigned char *addr)
 195 {
 196         struct net_bridge_fdb_entry *fdb;
 197
 198         rcu_read_lock();
 199         fdb = __br_fdb_get(br, addr);
 200         if (fdb && !atomic_inc_not_zero(&fdb->use_count))
 201                 fdb = NULL;
 202         rcu_read_unlock();
 203         return fdb;
 204 }
 205
 206 static void fdb_rcu_free(struct rcu_head *head)
 207 {
 208         struct net_bridge_fdb_entry *ent
 209                 = container_of(head, struct net_bridge_fdb_entry, rcu);
 210         kmem_cache_free(br_fdb_cache, ent);
 211 }
 212
 213 /* Set entry up for deletion with RCU  */
 214 void br_fdb_put(struct net_bridge_fdb_entry *ent)
 215 {
 216         if (atomic_dec_and_test(&ent->use_count))
 217                 call_rcu(&ent->rcu, fdb_rcu_free);
 218 }
 219
 220 /*
 221  * Fill buffer with forwarding table records in
 222  * the API format.
 223  */
 224 int br_fdb_fillbuf(struct net_bridge *br, void *buf,
 225                    unsigned long maxnum, unsigned long skip)
 226 {
 227         struct __fdb_entry *fe = buf;
 228         int i, num = 0;
 229         struct hlist_node *h;
 230         struct net_bridge_fdb_entry *f;
 231
 232         memset(buf, 0, maxnum*sizeof(struct __fdb_entry));
 233
 234         rcu_read_lock();
 235         for (i = 0; i < BR_HASH_SIZE; i++) {
 236                 hlist_for_each_entry_rcu(f, h, &br->hash[i], hlist) {
 237                         if (num >= maxnum)
 238                                 goto out;
 239
 240                         if (has_expired(br, f))
 241                                 continue;
 242
 243                         if (skip) {
 244                                 --skip;
 245                                 continue;
 246                         }
 247
 248                         /* convert from internal format to API */
 249                         memcpy(fe->mac_addr, f->addr.addr, ETH_ALEN);
 250                         fe->port_no = f->dst->port_no;
 251                         fe->is_local = f->is_local;
 252                         if (!f->is_static)
 253                                 fe->ageing_timer_value = jiffies_to_clock_t(jiffies - f->ageing_timer);
 254                         ++fe;
 255                         ++num;
 256                 }
 257         }
 258
 259  out:
 260         rcu_read_unlock();
 261
 262         return num;
 263 }
 264
 265 static inline struct net_bridge_fdb_entry *fdb_find(struct hlist_head *head,
 266                                                     const unsigned char *addr)
 267 {
 268         struct hlist_node *h;
 269         struct net_bridge_fdb_entry *fdb;
 270
 271         hlist_for_each_entry_rcu(fdb, h, head, hlist) {
 272                 if (!compare_ether_addr(fdb->addr.addr, addr))
 273                         return fdb;
 274         }
 275         return NULL;
 276 }
 277
 278 static struct net_bridge_fdb_entry *fdb_create(struct hlist_head *head,
 279                                                struct net_bridge_port *source,
 280                                                const unsigned char *addr,
 281                                                int is_local)
 282 {
 283         struct net_bridge_fdb_entry *fdb;
 284
 285         fdb = kmem_cache_alloc(br_fdb_cache, GFP_ATOMIC);
 286         if (fdb) {
 287                 memcpy(fdb->addr.addr, addr, ETH_ALEN);
 288                 atomic_set(&fdb->use_count, 1);
 289                 hlist_add_head_rcu(&fdb->hlist, head);
 290
 291                 fdb->dst = source;
 292                 fdb->is_local = is_local;
 293                 fdb->is_static = is_local;
 294                 fdb->ageing_timer = jiffies;
 295         }
 296         return fdb;
 297 }
 298
 299 static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
 300                   const unsigned char *addr)
 301 {
 302         struct hlist_head *head = &br->hash[br_mac_hash(addr)];
 303         struct net_bridge_fdb_entry *fdb;
 304
 305         if (!is_valid_ether_addr(addr))
 306                 return -EINVAL;
 307
 308         fdb = fdb_find(head, addr);
 309         if (fdb) {
 310                 /* it is okay to have multiple ports with same
 311                  * address, just use the first one.
 312                  */
 313                 if (fdb->is_local)
 314                         return 0;
 315
 316                 printk(KERN_WARNING "%s adding interface with same address "
 317                        "as a received packet\n",
 318                        source->dev->name);
 319                 fdb_delete(fdb);
 320         }
 321
 322         if (!fdb_create(head, source, addr, 1))
 323                 return -ENOMEM;
 324
 325         return 0;
 326 }
 327
 328 int br_fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
 329                   const unsigned char *addr)
 330 {
 331         int ret;
 332
 333         spin_lock_bh(&br->hash_lock);
 334         ret = fdb_insert(br, source, addr);
 335         spin_unlock_bh(&br->hash_lock);
 336         return ret;
 337 }
 338
 339 void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
 340                    const unsigned char *addr)
 341 {
 342         struct hlist_head *head = &br->hash[br_mac_hash(addr)];
 343         struct net_bridge_fdb_entry *fdb;
 344
 345         /* some users want to always flood. */
 346         if (hold_time(br) == 0)
 347                 return;
 348
 349         fdb = fdb_find(head, addr);
 350         if (likely(fdb)) {
 351                 /* attempt to update an entry for a local interface */
 352                 if (unlikely(fdb->is_local)) {
 353                         if (net_ratelimit())
 354                                 printk(KERN_WARNING "%s: received packet with "
 355                                        " own address as source address\n",
 356                                        source->dev->name);
 357                 } else {
 358                         /* fastpath: update of existing entry */
 359                         fdb->dst = source;
 360                         fdb->ageing_timer = jiffies;
 361                 }
 362         } else {
 363                 spin_lock(&br->hash_lock);
 364                 if (!fdb_find(head, addr))
 365                         fdb_create(head, source, addr, 0);
 366                 /* else  we lose race and someone else inserts
 367                  * it first, don't bother updating
 368                  */
 369                 spin_unlock(&br->hash_lock);
 370         }
 371 }