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, 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 __exit 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         int i;
 125
 126         spin_lock_bh(&br->hash_lock);
 127         for (i = 0; i < BR_HASH_SIZE; i++) {
 128                 struct net_bridge_fdb_entry *f;
 129                 struct hlist_node *h, *n;
 130
 131                 hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
 132                         if (!f->is_static &&
 133                             time_before_eq(f->ageing_timer + delay, jiffies))
 134                                 fdb_delete(f);
 135                 }
 136         }
 137         spin_unlock_bh(&br->hash_lock);
 138
 139         mod_timer(&br->gc_timer, jiffies + HZ/10);
 140 }
 141
 142 /* Completely flush all dynamic entries in forwarding database.*/
 143 void br_fdb_flush(struct net_bridge *br)
 144 {
 145         int i;
 146
 147         spin_lock_bh(&br->hash_lock);
 148         for (i = 0; i < BR_HASH_SIZE; i++) {
 149                 struct net_bridge_fdb_entry *f;
 150                 struct hlist_node *h, *n;
 151                 hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
 152                         if (!f->is_static)
 153                                 fdb_delete(f);
 154                 }
 155         }
 156         spin_unlock_bh(&br->hash_lock);
 157 }
 158
 159 /* Flush all entries refering to a specific port.
 160  * if do_all is set also flush static entries
 161  */
 162 void br_fdb_delete_by_port(struct net_bridge *br,
 163                            const struct net_bridge_port *p,
 164                            int do_all)
 165 {
 166         int i;
 167
 168         spin_lock_bh(&br->hash_lock);
 169         for (i = 0; i < BR_HASH_SIZE; i++) {
 170                 struct hlist_node *h, *g;
 171
 172                 hlist_for_each_safe(h, g, &br->hash[i]) {
 173                         struct net_bridge_fdb_entry *f
 174                                 = hlist_entry(h, struct net_bridge_fdb_entry, hlist);
 175                         if (f->dst != p)
 176                                 continue;
 177
 178                         if (f->is_static && !do_all)
 179                                 continue;
 180                         /*
 181                          * if multiple ports all have the same device address
 182                          * then when one port is deleted, assign
 183                          * the local entry to other port
 184                          */
 185                         if (f->is_local) {
 186                                 struct net_bridge_port *op;
 187                                 list_for_each_entry(op, &br->port_list, list) {
 188                                         if (op != p &&
 189                                             !compare_ether_addr(op->dev->dev_addr,
 190                                                                 f->addr.addr)) {
 191                                                 f->dst = op;
 192                                                 goto skip_delete;
 193                                         }
 194                                 }
 195                         }
 196
 197                         fdb_delete(f);
 198                 skip_delete: ;
 199                 }
 200         }
 201         spin_unlock_bh(&br->hash_lock);
 202 }
 203
 204 /* No locking or refcounting, assumes caller has no preempt (rcu_read_lock) */
 205 struct net_bridge_fdb_entry *__br_fdb_get(struct net_bridge *br,
 206                                           const unsigned char *addr)
 207 {
 208         struct hlist_node *h;
 209         struct net_bridge_fdb_entry *fdb;
 210
 211         hlist_for_each_entry_rcu(fdb, h, &br->hash[br_mac_hash(addr)], hlist) {
 212                 if (!compare_ether_addr(fdb->addr.addr, addr)) {
 213                         if (unlikely(has_expired(br, fdb)))
 214                                 break;
 215                         return fdb;
 216                 }
 217         }
 218
 219         return NULL;
 220 }
 221
 222 /* Interface used by ATM hook that keeps a ref count */
 223 struct net_bridge_fdb_entry *br_fdb_get(struct net_bridge *br,
 224                                         unsigned char *addr)
 225 {
 226         struct net_bridge_fdb_entry *fdb;
 227
 228         rcu_read_lock();
 229         fdb = __br_fdb_get(br, addr);
 230         if (fdb && !atomic_inc_not_zero(&fdb->use_count))
 231                 fdb = NULL;
 232         rcu_read_unlock();
 233         return fdb;
 234 }
 235
 236 static void fdb_rcu_free(struct rcu_head *head)
 237 {
 238         struct net_bridge_fdb_entry *ent
 239                 = container_of(head, struct net_bridge_fdb_entry, rcu);
 240         kmem_cache_free(br_fdb_cache, ent);
 241 }
 242
 243 /* Set entry up for deletion with RCU  */
 244 void br_fdb_put(struct net_bridge_fdb_entry *ent)
 245 {
 246         if (atomic_dec_and_test(&ent->use_count))
 247                 call_rcu(&ent->rcu, fdb_rcu_free);
 248 }
 249
 250 /*
 251  * Fill buffer with forwarding table records in
 252  * the API format.
 253  */
 254 int br_fdb_fillbuf(struct net_bridge *br, void *buf,
 255                    unsigned long maxnum, unsigned long skip)
 256 {
 257         struct __fdb_entry *fe = buf;
 258         int i, num = 0;
 259         struct hlist_node *h;
 260         struct net_bridge_fdb_entry *f;
 261
 262         memset(buf, 0, maxnum*sizeof(struct __fdb_entry));
 263
 264         rcu_read_lock();
 265         for (i = 0; i < BR_HASH_SIZE; i++) {
 266                 hlist_for_each_entry_rcu(f, h, &br->hash[i], hlist) {
 267                         if (num >= maxnum)
 268                                 goto out;
 269
 270                         if (has_expired(br, f))
 271                                 continue;
 272
 273                         if (skip) {
 274                                 --skip;
 275                                 continue;
 276                         }
 277
 278                         /* convert from internal format to API */
 279                         memcpy(fe->mac_addr, f->addr.addr, ETH_ALEN);
 280                         fe->port_no = f->dst->port_no;
 281                         fe->is_local = f->is_local;
 282                         if (!f->is_static)
 283                                 fe->ageing_timer_value = jiffies_to_clock_t(jiffies - f->ageing_timer);
 284                         ++fe;
 285                         ++num;
 286                 }
 287         }
 288
 289  out:
 290         rcu_read_unlock();
 291
 292         return num;
 293 }
 294
 295 static inline struct net_bridge_fdb_entry *fdb_find(struct hlist_head *head,
 296                                                     const unsigned char *addr)
 297 {
 298         struct hlist_node *h;
 299         struct net_bridge_fdb_entry *fdb;
 300
 301         hlist_for_each_entry_rcu(fdb, h, head, hlist) {
 302                 if (!compare_ether_addr(fdb->addr.addr, addr))
 303                         return fdb;
 304         }
 305         return NULL;
 306 }
 307
 308 static struct net_bridge_fdb_entry *fdb_create(struct hlist_head *head,
 309                                                struct net_bridge_port *source,
 310                                                const unsigned char *addr,
 311                                                int is_local)
 312 {
 313         struct net_bridge_fdb_entry *fdb;
 314
 315         fdb = kmem_cache_alloc(br_fdb_cache, GFP_ATOMIC);
 316         if (fdb) {
 317                 memcpy(fdb->addr.addr, addr, ETH_ALEN);
 318                 atomic_set(&fdb->use_count, 1);
 319                 hlist_add_head_rcu(&fdb->hlist, head);
 320
 321                 fdb->dst = source;
 322                 fdb->is_local = is_local;
 323                 fdb->is_static = is_local;
 324                 fdb->ageing_timer = jiffies;
 325         }
 326         return fdb;
 327 }
 328
 329 static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
 330                   const unsigned char *addr)
 331 {
 332         struct hlist_head *head = &br->hash[br_mac_hash(addr)];
 333         struct net_bridge_fdb_entry *fdb;
 334
 335         if (!is_valid_ether_addr(addr))
 336                 return -EINVAL;
 337
 338         fdb = fdb_find(head, addr);
 339         if (fdb) {
 340                 /* it is okay to have multiple ports with same
 341                  * address, just use the first one.
 342                  */
 343                 if (fdb->is_local)
 344                         return 0;
 345
 346                 printk(KERN_WARNING "%s adding interface with same address "
 347                        "as a received packet\n",
 348                        source->dev->name);
 349                 fdb_delete(fdb);
 350         }
 351
 352         if (!fdb_create(head, source, addr, 1))
 353                 return -ENOMEM;
 354
 355         return 0;
 356 }
 357
 358 int br_fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
 359                   const unsigned char *addr)
 360 {
 361         int ret;
 362
 363         spin_lock_bh(&br->hash_lock);
 364         ret = fdb_insert(br, source, addr);
 365         spin_unlock_bh(&br->hash_lock);
 366         return ret;
 367 }
 368
 369 void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
 370                    const unsigned char *addr)
 371 {
 372         struct hlist_head *head = &br->hash[br_mac_hash(addr)];
 373         struct net_bridge_fdb_entry *fdb;
 374
 375         /* some users want to always flood. */
 376         if (hold_time(br) == 0)
 377                 return;
 378
 379         fdb = fdb_find(head, addr);
 380         if (likely(fdb)) {
 381                 /* attempt to update an entry for a local interface */
 382                 if (unlikely(fdb->is_local)) {
 383                         if (net_ratelimit())
 384                                 printk(KERN_WARNING "%s: received packet with "
 385                                        " own address as source address\n",
 386                                        source->dev->name);
 387                 } else {
 388                         /* fastpath: update of existing entry */
 389                         fdb->dst = source;
 390                         fdb->ageing_timer = jiffies;
 391                 }
 392         } else {
 393                 spin_lock(&br->hash_lock);
 394                 if (!fdb_find(head, addr))
 395                         fdb_create(head, source, addr, 0);
 396                 /* else  we lose race and someone else inserts
 397                  * it first, don't bother updating
 398                  */
 399                 spin_unlock(&br->hash_lock);
 400         }
 401 }