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/rculist.h>
  19 #include <linux/spinlock.h>
  20 #include <linux/times.h>
  21 #include <linux/netdevice.h>
  22 #include <linux/etherdevice.h>
  23 #include <linux/jhash.h>
  24 #include <linux/random.h>
  25 #include <asm/atomic.h>
  26 #include <asm/unaligned.h>
  27 #include "br_private.h"
  28
  29 static struct kmem_cache *br_fdb_cache __read_mostly;
  30 static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
  31                       const unsigned char *addr);
  32
  33 static u32 fdb_salt __read_mostly;
  34
  35 int __init br_fdb_init(void)
  36 {
  37         br_fdb_cache = kmem_cache_create("bridge_fdb_cache",
  38                                          sizeof(struct net_bridge_fdb_entry),
  39                                          0,
  40                                          SLAB_HWCACHE_ALIGN, NULL);
  41         if (!br_fdb_cache)
  42                 return -ENOMEM;
  43
  44         get_random_bytes(&fdb_salt, sizeof(fdb_salt));
  45         return 0;
  46 }
  47
  48 void br_fdb_fini(void)
  49 {
  50         kmem_cache_destroy(br_fdb_cache);
  51 }
  52
  53
  54 /* if topology_changing then use forward_delay (default 15 sec)
  55  * otherwise keep longer (default 5 minutes)
  56  */
  57 static inline unsigned long hold_time(const struct net_bridge *br)
  58 {
  59         return br->topology_change ? br->forward_delay : br->ageing_time;
  60 }
  61
  62 static inline int has_expired(const struct net_bridge *br,
  63                                   const struct net_bridge_fdb_entry *fdb)
  64 {
  65         return !fdb->is_static
  66                 && time_before_eq(fdb->ageing_timer + hold_time(br), jiffies);
  67 }
  68
  69 static inline int br_mac_hash(const unsigned char *mac)
  70 {
  71         /* use 1 byte of OUI cnd 3 bytes of NIC */
  72         u32 key = get_unaligned((u32 *)(mac + 2));
  73         return jhash_1word(key, fdb_salt) & (BR_HASH_SIZE - 1);
  74 }
  75
  76 static inline void fdb_delete(struct net_bridge_fdb_entry *f)
  77 {
  78         hlist_del_rcu(&f->hlist);
  79         br_fdb_put(f);
  80 }
  81
  82 void br_fdb_changeaddr(struct net_bridge_port *p, const unsigned char *newaddr)
  83 {
  84         struct net_bridge *br = p->br;
  85         int i;
  86
  87         spin_lock_bh(&br->hash_lock);
  88
  89         /* Search all chains since old address/hash is unknown */
  90         for (i = 0; i < BR_HASH_SIZE; i++) {
  91                 struct hlist_node *h;
  92                 hlist_for_each(h, &br->hash[i]) {
  93                         struct net_bridge_fdb_entry *f;
  94
  95                         f = hlist_entry(h, struct net_bridge_fdb_entry, hlist);
  96                         if (f->dst == p && f->is_local) {
  97                                 /* maybe another port has same hw addr? */
  98                                 struct net_bridge_port *op;
  99                                 list_for_each_entry(op, &br->port_list, list) {
 100                                         if (op != p &&
 101                                             !compare_ether_addr(op->dev->dev_addr,
 102                                                                 f->addr.addr)) {
 103                                                 f->dst = op;
 104                                                 goto insert;
 105                                         }
 106                                 }
 107
 108                                 /* delete old one */
 109                                 fdb_delete(f);
 110                                 goto insert;
 111                         }
 112                 }
 113         }
 114  insert:
 115         /* insert new address,  may fail if invalid address or dup. */
 116         fdb_insert(br, p, newaddr);
 117
 118         spin_unlock_bh(&br->hash_lock);
 119 }
 120
 121 void br_fdb_cleanup(unsigned long _data)
 122 {
 123         struct net_bridge *br = (struct net_bridge *)_data;
 124         unsigned long delay = hold_time(br);
 125         unsigned long next_timer = jiffies + br->forward_delay;
 126         int i;
 127
 128         spin_lock_bh(&br->hash_lock);
 129         for (i = 0; i < BR_HASH_SIZE; i++) {
 130                 struct net_bridge_fdb_entry *f;
 131                 struct hlist_node *h, *n;
 132
 133                 hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
 134                         unsigned long this_timer;
 135                         if (f->is_static)
 136                                 continue;
 137                         this_timer = f->ageing_timer + delay;
 138                         if (time_before_eq(this_timer, jiffies))
 139                                 fdb_delete(f);
 140                         else if (time_before(this_timer, next_timer))
 141                                 next_timer = this_timer;
 142                 }
 143         }
 144         spin_unlock_bh(&br->hash_lock);
 145
 146         /* Add HZ/4 to ensure we round the jiffies upwards to be after the next
 147          * timer, otherwise we might round down and will have no-op run. */
 148         mod_timer(&br->gc_timer, round_jiffies(next_timer + HZ/4));
 149 }
 150
 151 /* Completely flush all dynamic entries in forwarding database.*/
 152 void br_fdb_flush(struct net_bridge *br)
 153 {
 154         int i;
 155
 156         spin_lock_bh(&br->hash_lock);
 157         for (i = 0; i < BR_HASH_SIZE; i++) {
 158                 struct net_bridge_fdb_entry *f;
 159                 struct hlist_node *h, *n;
 160                 hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
 161                         if (!f->is_static)
 162                                 fdb_delete(f);
 163                 }
 164         }
 165         spin_unlock_bh(&br->hash_lock);
 166 }
 167
 168 /* Flush all entries refering to a specific port.
 169  * if do_all is set also flush static entries
 170  */
 171 void br_fdb_delete_by_port(struct net_bridge *br,
 172                            const struct net_bridge_port *p,
 173                            int do_all)
 174 {
 175         int i;
 176
 177         spin_lock_bh(&br->hash_lock);
 178         for (i = 0; i < BR_HASH_SIZE; i++) {
 179                 struct hlist_node *h, *g;
 180
 181                 hlist_for_each_safe(h, g, &br->hash[i]) {
 182                         struct net_bridge_fdb_entry *f
 183                                 = hlist_entry(h, struct net_bridge_fdb_entry, hlist);
 184                         if (f->dst != p)
 185                                 continue;
 186
 187                         if (f->is_static && !do_all)
 188                                 continue;
 189                         /*
 190                          * if multiple ports all have the same device address
 191                          * then when one port is deleted, assign
 192                          * the local entry to other port
 193                          */
 194                         if (f->is_local) {
 195                                 struct net_bridge_port *op;
 196                                 list_for_each_entry(op, &br->port_list, list) {
 197                                         if (op != p &&
 198                                             !compare_ether_addr(op->dev->dev_addr,
 199                                                                 f->addr.addr)) {
 200                                                 f->dst = op;
 201                                                 goto skip_delete;
 202                                         }
 203                                 }
 204                         }
 205
 206                         fdb_delete(f);
 207                 skip_delete: ;
 208                 }
 209         }
 210         spin_unlock_bh(&br->hash_lock);
 211 }
 212
 213 /* No locking or refcounting, assumes caller has no preempt (rcu_read_lock) */
 214 struct net_bridge_fdb_entry *__br_fdb_get(struct net_bridge *br,
 215                                           const unsigned char *addr)
 216 {
 217         struct hlist_node *h;
 218         struct net_bridge_fdb_entry *fdb;
 219
 220         hlist_for_each_entry_rcu(fdb, h, &br->hash[br_mac_hash(addr)], hlist) {
 221                 if (!compare_ether_addr(fdb->addr.addr, addr)) {
 222                         if (unlikely(has_expired(br, fdb)))
 223                                 break;
 224                         return fdb;
 225                 }
 226         }
 227
 228         return NULL;
 229 }
 230
 231 /* Interface used by ATM hook that keeps a ref count */
 232 struct net_bridge_fdb_entry *br_fdb_get(struct net_bridge *br,
 233                                         unsigned char *addr)
 234 {
 235         struct net_bridge_fdb_entry *fdb;
 236
 237         rcu_read_lock();
 238         fdb = __br_fdb_get(br, addr);
 239         if (fdb && !atomic_inc_not_zero(&fdb->use_count))
 240                 fdb = NULL;
 241         rcu_read_unlock();
 242         return fdb;
 243 }
 244
 245 static void fdb_rcu_free(struct rcu_head *head)
 246 {
 247         struct net_bridge_fdb_entry *ent
 248                 = container_of(head, struct net_bridge_fdb_entry, rcu);
 249         kmem_cache_free(br_fdb_cache, ent);
 250 }
 251
 252 /* Set entry up for deletion with RCU  */
 253 void br_fdb_put(struct net_bridge_fdb_entry *ent)
 254 {
 255         if (atomic_dec_and_test(&ent->use_count))
 256                 call_rcu(&ent->rcu, fdb_rcu_free);
 257 }
 258
 259 /*
 260  * Fill buffer with forwarding table records in
 261  * the API format.
 262  */
 263 int br_fdb_fillbuf(struct net_bridge *br, void *buf,
 264                    unsigned long maxnum, unsigned long skip)
 265 {
 266         struct __fdb_entry *fe = buf;
 267         int i, num = 0;
 268         struct hlist_node *h;
 269         struct net_bridge_fdb_entry *f;
 270
 271         memset(buf, 0, maxnum*sizeof(struct __fdb_entry));
 272
 273         rcu_read_lock();
 274         for (i = 0; i < BR_HASH_SIZE; i++) {
 275                 hlist_for_each_entry_rcu(f, h, &br->hash[i], hlist) {
 276                         if (num >= maxnum)
 277                                 goto out;
 278
 279                         if (has_expired(br, f))
 280                                 continue;
 281
 282                         if (skip) {
 283                                 --skip;
 284                                 continue;
 285                         }
 286
 287                         /* convert from internal format to API */
 288                         memcpy(fe->mac_addr, f->addr.addr, ETH_ALEN);
 289
 290                         /* due to ABI compat need to split into hi/lo */
 291                         fe->port_no = f->dst->port_no;
 292                         fe->port_hi = f->dst->port_no >> 8;
 293
 294                         fe->is_local = f->is_local;
 295                         if (!f->is_static)
 296                                 fe->ageing_timer_value = jiffies_to_clock_t(jiffies - f->ageing_timer);
 297                         ++fe;
 298                         ++num;
 299                 }
 300         }
 301
 302  out:
 303         rcu_read_unlock();
 304
 305         return num;
 306 }
 307
 308 static inline struct net_bridge_fdb_entry *fdb_find(struct hlist_head *head,
 309                                                     const unsigned char *addr)
 310 {
 311         struct hlist_node *h;
 312         struct net_bridge_fdb_entry *fdb;
 313
 314         hlist_for_each_entry_rcu(fdb, h, head, hlist) {
 315                 if (!compare_ether_addr(fdb->addr.addr, addr))
 316                         return fdb;
 317         }
 318         return NULL;
 319 }
 320
 321 static struct net_bridge_fdb_entry *fdb_create(struct hlist_head *head,
 322                                                struct net_bridge_port *source,
 323                                                const unsigned char *addr,
 324                                                int is_local)
 325 {
 326         struct net_bridge_fdb_entry *fdb;
 327
 328         fdb = kmem_cache_alloc(br_fdb_cache, GFP_ATOMIC);
 329         if (fdb) {
 330                 memcpy(fdb->addr.addr, addr, ETH_ALEN);
 331                 atomic_set(&fdb->use_count, 1);
 332                 hlist_add_head_rcu(&fdb->hlist, head);
 333
 334                 fdb->dst = source;
 335                 fdb->is_local = is_local;
 336                 fdb->is_static = is_local;
 337                 fdb->ageing_timer = jiffies;
 338         }
 339         return fdb;
 340 }
 341
 342 static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
 343                   const unsigned char *addr)
 344 {
 345         struct hlist_head *head = &br->hash[br_mac_hash(addr)];
 346         struct net_bridge_fdb_entry *fdb;
 347
 348         if (!is_valid_ether_addr(addr))
 349                 return -EINVAL;
 350
 351         fdb = fdb_find(head, addr);
 352         if (fdb) {
 353                 /* it is okay to have multiple ports with same
 354                  * address, just use the first one.
 355                  */
 356                 if (fdb->is_local)
 357                         return 0;
 358
 359                 printk(KERN_WARNING "%s adding interface with same address "
 360                        "as a received packet\n",
 361                        source->dev->name);
 362                 fdb_delete(fdb);
 363         }
 364
 365         if (!fdb_create(head, source, addr, 1))
 366                 return -ENOMEM;
 367
 368         return 0;
 369 }
 370
 371 int br_fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
 372                   const unsigned char *addr)
 373 {
 374         int ret;
 375
 376         spin_lock_bh(&br->hash_lock);
 377         ret = fdb_insert(br, source, addr);
 378         spin_unlock_bh(&br->hash_lock);
 379         return ret;
 380 }
 381
 382 void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
 383                    const unsigned char *addr)
 384 {
 385         struct hlist_head *head = &br->hash[br_mac_hash(addr)];
 386         struct net_bridge_fdb_entry *fdb;
 387
 388         /* some users want to always flood. */
 389         if (hold_time(br) == 0)
 390                 return;
 391
 392         /* ignore packets unless we are using this port */
 393         if (!(source->state == BR_STATE_LEARNING ||
 394               source->state == BR_STATE_FORWARDING))
 395                 return;
 396
 397         fdb = fdb_find(head, addr);
 398         if (likely(fdb)) {
 399                 /* attempt to update an entry for a local interface */
 400                 if (unlikely(fdb->is_local)) {
 401                         if (net_ratelimit())
 402                                 printk(KERN_WARNING "%s: received packet with "
 403                                        " own address as source address\n",
 404                                        source->dev->name);
 405                 } else {
 406                         /* fastpath: update of existing entry */
 407                         fdb->dst = source;
 408                         fdb->ageing_timer = jiffies;
 409                 }
 410         } else {
 411                 spin_lock(&br->hash_lock);
 412                 if (!fdb_find(head, addr))
 413                         fdb_create(head, source, addr, 0);
 414                 /* else  we lose race and someone else inserts
 415                  * it first, don't bother updating
 416                  */
 417                 spin_unlock(&br->hash_lock);
 418         }
 419 }