net/bridge/br_fdb.c

   1 /*
   2  *      Forwarding database
   3  *      Linux ethernet bridge
   4  *
   5  *      Authors:
   6  *      Lennert Buytenhek               <buytenh@gnu.org>
   7  *
   8  *      This program is free software; you can redistribute it and/or
   9  *      modify it under the terms of the GNU General Public License
  10  *      as published by the Free Software Foundation; either version
  11  *      2 of the License, or (at your option) any later version.
  12  */
  13
  14 #include <linux/kernel.h>
  15 #include <linux/init.h>
  16 #include <linux/rculist.h>
  17 #include <linux/spinlock.h>
  18 #include <linux/times.h>
  19 #include <linux/netdevice.h>
  20 #include <linux/etherdevice.h>
  21 #include <linux/jhash.h>
  22 #include <linux/random.h>
  23 #include <linux/slab.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);
  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 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 void fdb_rcu_free(struct rcu_head *head)
  76 {
  77         struct net_bridge_fdb_entry *ent
  78                 = container_of(head, struct net_bridge_fdb_entry, rcu);
  79         kmem_cache_free(br_fdb_cache, ent);
  80 }
  81
  82 static inline void fdb_delete(struct net_bridge_fdb_entry *f)
  83 {
  84         hlist_del_rcu(&f->hlist);
  85         call_rcu(&f->rcu, fdb_rcu_free);
  86 }
  87
  88 void br_fdb_changeaddr(struct net_bridge_port *p, const unsigned char *newaddr)
  89 {
  90         struct net_bridge *br = p->br;
  91         int i;
  92
  93         spin_lock_bh(&br->hash_lock);
  94
  95         /* Search all chains since old address/hash is unknown */
  96         for (i = 0; i < BR_HASH_SIZE; i++) {
  97                 struct hlist_node *h;
  98                 hlist_for_each(h, &br->hash[i]) {
  99                         struct net_bridge_fdb_entry *f;
 100
 101                         f = hlist_entry(h, struct net_bridge_fdb_entry, hlist);
 102                         if (f->dst == p && f->is_local) {
 103                                 /* maybe another port has same hw addr? */
 104                                 struct net_bridge_port *op;
 105                                 list_for_each_entry(op, &br->port_list, list) {
 106                                         if (op != p &&
 107                                             !compare_ether_addr(op->dev->dev_addr,
 108                                                                 f->addr.addr)) {
 109                                                 f->dst = op;
 110                                                 goto insert;
 111                                         }
 112                                 }
 113
 114                                 /* delete old one */
 115                                 fdb_delete(f);
 116                                 goto insert;
 117                         }
 118                 }
 119         }
 120  insert:
 121         /* insert new address,  may fail if invalid address or dup. */
 122         fdb_insert(br, p, newaddr);
 123
 124         spin_unlock_bh(&br->hash_lock);
 125 }
 126
 127 void br_fdb_cleanup(unsigned long _data)
 128 {
 129         struct net_bridge *br = (struct net_bridge *)_data;
 130         unsigned long delay = hold_time(br);
 131         unsigned long next_timer = jiffies + br->forward_delay;
 132         int i;
 133
 134         spin_lock_bh(&br->hash_lock);
 135         for (i = 0; i < BR_HASH_SIZE; i++) {
 136                 struct net_bridge_fdb_entry *f;
 137                 struct hlist_node *h, *n;
 138
 139                 hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
 140                         unsigned long this_timer;
 141                         if (f->is_static)
 142                                 continue;
 143                         this_timer = f->ageing_timer + delay;
 144                         if (time_before_eq(this_timer, jiffies))
 145                                 fdb_delete(f);
 146                         else if (time_before(this_timer, next_timer))
 147                                 next_timer = this_timer;
 148                 }
 149         }
 150         spin_unlock_bh(&br->hash_lock);
 151
 152         /* Add HZ/4 to ensure we round the jiffies upwards to be after the next
 153          * timer, otherwise we might round down and will have no-op run. */
 154         mod_timer(&br->gc_timer, round_jiffies(next_timer + HZ/4));
 155 }
 156
 157 /* Completely flush all dynamic entries in forwarding database.*/
 158 void br_fdb_flush(struct net_bridge *br)
 159 {
 160         int i;
 161
 162         spin_lock_bh(&br->hash_lock);
 163         for (i = 0; i < BR_HASH_SIZE; i++) {
 164                 struct net_bridge_fdb_entry *f;
 165                 struct hlist_node *h, *n;
 166                 hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
 167                         if (!f->is_static)
 168                                 fdb_delete(f);
 169                 }
 170         }
 171         spin_unlock_bh(&br->hash_lock);
 172 }
 173
 174 /* Flush all entries refering to a specific port.
 175  * if do_all is set also flush static entries
 176  */
 177 void br_fdb_delete_by_port(struct net_bridge *br,
 178                            const struct net_bridge_port *p,
 179                            int do_all)
 180 {
 181         int i;
 182
 183         spin_lock_bh(&br->hash_lock);
 184         for (i = 0; i < BR_HASH_SIZE; i++) {
 185                 struct hlist_node *h, *g;
 186
 187                 hlist_for_each_safe(h, g, &br->hash[i]) {
 188                         struct net_bridge_fdb_entry *f
 189                                 = hlist_entry(h, struct net_bridge_fdb_entry, hlist);
 190                         if (f->dst != p)
 191                                 continue;
 192
 193                         if (f->is_static && !do_all)
 194                                 continue;
 195                         /*
 196                          * if multiple ports all have the same device address
 197                          * then when one port is deleted, assign
 198                          * the local entry to other port
 199                          */
 200                         if (f->is_local) {
 201                                 struct net_bridge_port *op;
 202                                 list_for_each_entry(op, &br->port_list, list) {
 203                                         if (op != p &&
 204                                             !compare_ether_addr(op->dev->dev_addr,
 205                                                                 f->addr.addr)) {
 206                                                 f->dst = op;
 207                                                 goto skip_delete;
 208                                         }
 209                                 }
 210                         }
 211
 212                         fdb_delete(f);
 213                 skip_delete: ;
 214                 }
 215         }
 216         spin_unlock_bh(&br->hash_lock);
 217 }
 218
 219 /* No locking or refcounting, assumes caller has no preempt (rcu_read_lock) */
 220 struct net_bridge_fdb_entry *__br_fdb_get(struct net_bridge *br,
 221                                           const unsigned char *addr)
 222 {
 223         struct hlist_node *h;
 224         struct net_bridge_fdb_entry *fdb;
 225
 226         hlist_for_each_entry_rcu(fdb, h, &br->hash[br_mac_hash(addr)], hlist) {
 227                 if (!compare_ether_addr(fdb->addr.addr, addr)) {
 228                         if (unlikely(has_expired(br, fdb)))
 229                                 break;
 230                         return fdb;
 231                 }
 232         }
 233
 234         return NULL;
 235 }
 236
 237 #if defined(CONFIG_ATM_LANE) || defined(CONFIG_ATM_LANE_MODULE)
 238 /* Interface used by ATM LANE hook to test
 239  * if an addr is on some other bridge port */
 240 int br_fdb_test_addr(struct net_device *dev, unsigned char *addr)
 241 {
 242         struct net_bridge_fdb_entry *fdb;
 243         int ret;
 244
 245         if (!dev->br_port)
 246                 return 0;
 247
 248         rcu_read_lock();
 249         fdb = __br_fdb_get(dev->br_port->br, addr);
 250         ret = fdb && fdb->dst->dev != dev &&
 251                 fdb->dst->state == BR_STATE_FORWARDING;
 252         rcu_read_unlock();
 253
 254         return ret;
 255 }
 256 #endif /* CONFIG_ATM_LANE */
 257
 258 /*
 259  * Fill buffer with forwarding table records in
 260  * the API format.
 261  */
 262 int br_fdb_fillbuf(struct net_bridge *br, void *buf,
 263                    unsigned long maxnum, unsigned long skip)
 264 {
 265         struct __fdb_entry *fe = buf;
 266         int i, num = 0;
 267         struct hlist_node *h;
 268         struct net_bridge_fdb_entry *f;
 269
 270         memset(buf, 0, maxnum*sizeof(struct __fdb_entry));
 271
 272         rcu_read_lock();
 273         for (i = 0; i < BR_HASH_SIZE; i++) {
 274                 hlist_for_each_entry_rcu(f, h, &br->hash[i], hlist) {
 275                         if (num >= maxnum)
 276                                 goto out;
 277
 278                         if (has_expired(br, f))
 279                                 continue;
 280
 281                         if (skip) {
 282                                 --skip;
 283                                 continue;
 284                         }
 285
 286                         /* convert from internal format to API */
 287                         memcpy(fe->mac_addr, f->addr.addr, ETH_ALEN);
 288
 289                         /* due to ABI compat need to split into hi/lo */
 290                         fe->port_no = f->dst->port_no;
 291                         fe->port_hi = f->dst->port_no >> 8;
 292
 293                         fe->is_local = f->is_local;
 294                         if (!f->is_static)
 295                                 fe->ageing_timer_value = jiffies_to_clock_t(jiffies - f->ageing_timer);
 296                         ++fe;
 297                         ++num;
 298                 }
 299         }
 300
 301  out:
 302         rcu_read_unlock();
 303
 304         return num;
 305 }
 306
 307 static inline struct net_bridge_fdb_entry *fdb_find(struct hlist_head *head,
 308                                                     const unsigned char *addr)
 309 {
 310         struct hlist_node *h;
 311         struct net_bridge_fdb_entry *fdb;
 312
 313         hlist_for_each_entry_rcu(fdb, h, head, hlist) {
 314                 if (!compare_ether_addr(fdb->addr.addr, addr))
 315                         return fdb;
 316         }
 317         return NULL;
 318 }
 319
 320 static struct net_bridge_fdb_entry *fdb_create(struct hlist_head *head,
 321                                                struct net_bridge_port *source,
 322                                                const unsigned char *addr,
 323                                                int is_local)
 324 {
 325         struct net_bridge_fdb_entry *fdb;
 326
 327         fdb = kmem_cache_alloc(br_fdb_cache, GFP_ATOMIC);
 328         if (fdb) {
 329                 memcpy(fdb->addr.addr, addr, ETH_ALEN);
 330                 hlist_add_head_rcu(&fdb->hlist, head);
 331
 332                 fdb->dst = source;
 333                 fdb->is_local = is_local;
 334                 fdb->is_static = is_local;
 335                 fdb->ageing_timer = jiffies;
 336         }
 337         return fdb;
 338 }
 339
 340 static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
 341                   const unsigned char *addr)
 342 {
 343         struct hlist_head *head = &br->hash[br_mac_hash(addr)];
 344         struct net_bridge_fdb_entry *fdb;
 345
 346         if (!is_valid_ether_addr(addr))
 347                 return -EINVAL;
 348
 349         fdb = fdb_find(head, addr);
 350         if (fdb) {
 351                 /* it is okay to have multiple ports with same
 352                  * address, just use the first one.
 353                  */
 354                 if (fdb->is_local)
 355                         return 0;
 356                 br_warn(br, "adding interface %s with same address "
 357                        "as a received packet\n",
 358                        source->dev->name);
 359                 fdb_delete(fdb);
 360         }
 361
 362         if (!fdb_create(head, source, addr, 1))
 363                 return -ENOMEM;
 364
 365         return 0;
 366 }
 367
 368 int br_fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
 369                   const unsigned char *addr)
 370 {
 371         int ret;
 372
 373         spin_lock_bh(&br->hash_lock);
 374         ret = fdb_insert(br, source, addr);
 375         spin_unlock_bh(&br->hash_lock);
 376         return ret;
 377 }
 378
 379 void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
 380                    const unsigned char *addr)
 381 {
 382         struct hlist_head *head = &br->hash[br_mac_hash(addr)];
 383         struct net_bridge_fdb_entry *fdb;
 384
 385         /* some users want to always flood. */
 386         if (hold_time(br) == 0)
 387                 return;
 388
 389         /* ignore packets unless we are using this port */
 390         if (!(source->state == BR_STATE_LEARNING ||
 391               source->state == BR_STATE_FORWARDING))
 392                 return;
 393
 394         fdb = fdb_find(head, addr);
 395         if (likely(fdb)) {
 396                 /* attempt to update an entry for a local interface */
 397                 if (unlikely(fdb->is_local)) {
 398                         if (net_ratelimit())
 399                                 br_warn(br, "received packet on %s with "
 400                                         "own address as source address\n",
 401                                         source->dev->name);
 402                 } else {
 403                         /* fastpath: update of existing entry */
 404                         fdb->dst = source;
 405                         fdb->ageing_timer = jiffies;
 406                 }
 407         } else {
 408                 spin_lock(&br->hash_lock);
 409                 if (!fdb_find(head, addr))
 410                         fdb_create(head, source, addr, 0);
 411                 /* else  we lose race and someone else inserts
 412                  * it first, don't bother updating
 413                  */
 414                 spin_unlock(&br->hash_lock);
 415         }
 416 }