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