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 <asm/atomic.h>
  23 #include "br_private.h"
  24
  25 static kmem_cache_t *br_fdb_cache;
  26 static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
  27                       const unsigned char *addr, int is_local);
  28
  29 void __init br_fdb_init(void)
  30 {
  31         br_fdb_cache = kmem_cache_create("bridge_fdb_cache",
  32                                          sizeof(struct net_bridge_fdb_entry),
  33                                          0,
  34                                          SLAB_HWCACHE_ALIGN, NULL, NULL);
  35 }
  36
  37 void __exit br_fdb_fini(void)
  38 {
  39         kmem_cache_destroy(br_fdb_cache);
  40 }
  41
  42
  43 /* if topology_changing then use forward_delay (default 15 sec)
  44  * otherwise keep longer (default 5 minutes)
  45  */
  46 static __inline__ unsigned long hold_time(const struct net_bridge *br)
  47 {
  48         return br->topology_change ? br->forward_delay : br->ageing_time;
  49 }
  50
  51 static __inline__ int has_expired(const struct net_bridge *br,
  52                                   const struct net_bridge_fdb_entry *fdb)
  53 {
  54         return !fdb->is_static
  55                 && time_before_eq(fdb->ageing_timer + hold_time(br), jiffies);
  56 }
  57
  58 static __inline__ int br_mac_hash(const unsigned char *mac)
  59 {
  60         unsigned long x;
  61
  62         x = mac[0];
  63         x = (x << 2) ^ mac[1];
  64         x = (x << 2) ^ mac[2];
  65         x = (x << 2) ^ mac[3];
  66         x = (x << 2) ^ mac[4];
  67         x = (x << 2) ^ mac[5];
  68
  69         x ^= x >> 8;
  70
  71         return x & (BR_HASH_SIZE - 1);
  72 }
  73
  74 static __inline__ void fdb_delete(struct net_bridge_fdb_entry *f)
  75 {
  76         hlist_del_rcu(&f->hlist);
  77         if (!f->is_static)
  78                 list_del(&f->u.age_list);
  79
  80         br_fdb_put(f);
  81 }
  82
  83 void br_fdb_changeaddr(struct net_bridge_port *p, const unsigned char *newaddr)
  84 {
  85         struct net_bridge *br = p->br;
  86         int i;
  87
  88         spin_lock_bh(&br->hash_lock);
  89
  90         /* Search all chains since old address/hash is unknown */
  91         for (i = 0; i < BR_HASH_SIZE; i++) {
  92                 struct hlist_node *h;
  93                 hlist_for_each(h, &br->hash[i]) {
  94                         struct net_bridge_fdb_entry *f;
  95
  96                         f = hlist_entry(h, struct net_bridge_fdb_entry, hlist);
  97                         if (f->dst == p && f->is_local) {
  98                                 /* maybe another port has same hw addr? */
  99                                 struct net_bridge_port *op;
 100                                 list_for_each_entry(op, &br->port_list, list) {
 101                                         if (op != p &&
 102                                             !memcmp(op->dev->dev_addr,
 103                                                     f->addr.addr, ETH_ALEN)) {
 104                                                 f->dst = op;
 105                                                 goto insert;
 106                                         }
 107                                 }
 108
 109                                 /* delete old one */
 110                                 fdb_delete(f);
 111                                 goto insert;
 112                         }
 113                 }
 114         }
 115  insert:
 116         /* insert new address,  may fail if invalid address or dup. */
 117         fdb_insert(br, p, newaddr, 1);
 118
 119
 120         spin_unlock_bh(&br->hash_lock);
 121 }
 122
 123 void br_fdb_cleanup(unsigned long _data)
 124 {
 125         struct net_bridge *br = (struct net_bridge *)_data;
 126         struct list_head *l, *n;
 127         unsigned long delay;
 128
 129         spin_lock_bh(&br->hash_lock);
 130         delay = hold_time(br);
 131
 132         list_for_each_safe(l, n, &br->age_list) {
 133                 struct net_bridge_fdb_entry *f;
 134                 unsigned long expires;
 135
 136                 f = list_entry(l, struct net_bridge_fdb_entry, u.age_list);
 137                 expires = f->ageing_timer + delay;
 138
 139                 if (time_before_eq(expires, jiffies)) {
 140                         WARN_ON(f->is_static);
 141                         pr_debug("expire age %lu jiffies %lu\n",
 142                                  f->ageing_timer, jiffies);
 143                         fdb_delete(f);
 144                 } else {
 145                         mod_timer(&br->gc_timer, expires);
 146                         break;
 147                 }
 148         }
 149         spin_unlock_bh(&br->hash_lock);
 150 }
 151
 152 void br_fdb_delete_by_port(struct net_bridge *br, struct net_bridge_port *p)
 153 {
 154         int i;
 155
 156         spin_lock_bh(&br->hash_lock);
 157         for (i = 0; i < BR_HASH_SIZE; i++) {
 158                 struct hlist_node *h, *g;
 159
 160                 hlist_for_each_safe(h, g, &br->hash[i]) {
 161                         struct net_bridge_fdb_entry *f
 162                                 = hlist_entry(h, struct net_bridge_fdb_entry, hlist);
 163                         if (f->dst != p)
 164                                 continue;
 165
 166                         /*
 167                          * if multiple ports all have the same device address
 168                          * then when one port is deleted, assign
 169                          * the local entry to other port
 170                          */
 171                         if (f->is_local) {
 172                                 struct net_bridge_port *op;
 173                                 list_for_each_entry(op, &br->port_list, list) {
 174                                         if (op != p &&
 175                                             !memcmp(op->dev->dev_addr,
 176                                                     f->addr.addr, ETH_ALEN)) {
 177                                                 f->dst = op;
 178                                                 goto skip_delete;
 179                                         }
 180                                 }
 181                         }
 182
 183                         fdb_delete(f);
 184                 skip_delete: ;
 185                 }
 186         }
 187         spin_unlock_bh(&br->hash_lock);
 188 }
 189
 190 /* No locking or refcounting, assumes caller has no preempt (rcu_read_lock) */
 191 struct net_bridge_fdb_entry *__br_fdb_get(struct net_bridge *br,
 192                                           const unsigned char *addr)
 193 {
 194         struct hlist_node *h;
 195         struct net_bridge_fdb_entry *fdb;
 196
 197         hlist_for_each_entry_rcu(fdb, h, &br->hash[br_mac_hash(addr)], hlist) {
 198                 if (!memcmp(fdb->addr.addr, addr, ETH_ALEN)) {
 199                         if (unlikely(has_expired(br, fdb)))
 200                                 break;
 201                         return fdb;
 202                 }
 203         }
 204
 205         return NULL;
 206 }
 207
 208 /* Interface used by ATM hook that keeps a ref count */
 209 struct net_bridge_fdb_entry *br_fdb_get(struct net_bridge *br,
 210                                         unsigned char *addr)
 211 {
 212         struct net_bridge_fdb_entry *fdb;
 213
 214         rcu_read_lock();
 215         fdb = __br_fdb_get(br, addr);
 216         if (fdb)
 217                 atomic_inc(&fdb->use_count);
 218         rcu_read_unlock();
 219         return fdb;
 220 }
 221
 222 static void fdb_rcu_free(struct rcu_head *head)
 223 {
 224         struct net_bridge_fdb_entry *ent
 225                 = container_of(head, struct net_bridge_fdb_entry, u.rcu);
 226         kmem_cache_free(br_fdb_cache, ent);
 227 }
 228
 229 /* Set entry up for deletion with RCU  */
 230 void br_fdb_put(struct net_bridge_fdb_entry *ent)
 231 {
 232         if (atomic_dec_and_test(&ent->use_count))
 233                 call_rcu(&ent->u.rcu, fdb_rcu_free);
 234 }
 235
 236 /*
 237  * Fill buffer with forwarding table records in
 238  * the API format.
 239  */
 240 int br_fdb_fillbuf(struct net_bridge *br, void *buf,
 241                    unsigned long maxnum, unsigned long skip)
 242 {
 243         struct __fdb_entry *fe = buf;
 244         int i, num = 0;
 245         struct hlist_node *h;
 246         struct net_bridge_fdb_entry *f;
 247
 248         memset(buf, 0, maxnum*sizeof(struct __fdb_entry));
 249
 250         rcu_read_lock();
 251         for (i = 0; i < BR_HASH_SIZE; i++) {
 252                 hlist_for_each_entry_rcu(f, h, &br->hash[i], hlist) {
 253                         if (num >= maxnum)
 254                                 goto out;
 255
 256                         if (has_expired(br, f))
 257                                 continue;
 258
 259                         if (skip) {
 260                                 --skip;
 261                                 continue;
 262                         }
 263
 264                         /* convert from internal format to API */
 265                         memcpy(fe->mac_addr, f->addr.addr, ETH_ALEN);
 266                         fe->port_no = f->dst->port_no;
 267                         fe->is_local = f->is_local;
 268                         if (!f->is_static)
 269                                 fe->ageing_timer_value = jiffies_to_clock_t(jiffies - f->ageing_timer);
 270                         ++fe;
 271                         ++num;
 272                 }
 273         }
 274
 275  out:
 276         rcu_read_unlock();
 277
 278         return num;
 279 }
 280
 281 static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
 282                   const unsigned char *addr, int is_local)
 283 {
 284         struct hlist_node *h;
 285         struct net_bridge_fdb_entry *fdb;
 286         int hash = br_mac_hash(addr);
 287
 288         if (!is_valid_ether_addr(addr))
 289                 return -EADDRNOTAVAIL;
 290
 291         hlist_for_each_entry(fdb, h, &br->hash[hash], hlist) {
 292                 if (!memcmp(fdb->addr.addr, addr, ETH_ALEN)) {
 293                         /* attempt to update an entry for a local interface */
 294                         if (fdb->is_local) {
 295                                 /* it is okay to have multiple ports with same
 296                                  * address, just don't allow to be spoofed.
 297                                  */
 298                                 if (is_local)
 299                                         return 0;
 300
 301                                 if (net_ratelimit())
 302                                         printk(KERN_WARNING "%s: received packet with "
 303                                                " own address as source address\n",
 304                                                source->dev->name);
 305                                 return -EEXIST;
 306                         }
 307
 308                         if (is_local) {
 309                                 printk(KERN_WARNING "%s adding interface with same address "
 310                                        "as a received packet\n",
 311                                        source->dev->name);
 312                                 goto update;
 313                         }
 314
 315                         if (fdb->is_static)
 316                                 return 0;
 317
 318                         /* move to end of age list */
 319                         list_del(&fdb->u.age_list);
 320                         goto update;
 321                 }
 322         }
 323
 324         fdb = kmem_cache_alloc(br_fdb_cache, GFP_ATOMIC);
 325         if (!fdb)
 326                 return ENOMEM;
 327
 328         memcpy(fdb->addr.addr, addr, ETH_ALEN);
 329         atomic_set(&fdb->use_count, 1);
 330         hlist_add_head_rcu(&fdb->hlist, &br->hash[hash]);
 331
 332         if (!timer_pending(&br->gc_timer)) {
 333                 br->gc_timer.expires = jiffies + hold_time(br);
 334                 add_timer(&br->gc_timer);
 335         }
 336
 337  update:
 338         fdb->dst = source;
 339         fdb->is_local = is_local;
 340         fdb->is_static = is_local;
 341         fdb->ageing_timer = jiffies;
 342         if (!is_local)
 343                 list_add_tail(&fdb->u.age_list, &br->age_list);
 344
 345         return 0;
 346 }
 347
 348 int br_fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
 349                   const unsigned char *addr, int is_local)
 350 {
 351         int ret;
 352
 353         spin_lock_bh(&br->hash_lock);
 354         ret = fdb_insert(br, source, addr, is_local);
 355         spin_unlock_bh(&br->hash_lock);
 356         return ret;
 357 }