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(&f->hlist);
  77         if (!f->is_static)
  78                 list_del(&f->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         write_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         write_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         write_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                         = list_entry(l, struct net_bridge_fdb_entry, age_list);
 135                 unsigned long expires = f->ageing_timer + delay;
 136
 137                 if (time_before_eq(expires, jiffies)) {
 138                         WARN_ON(f->is_static);
 139                         pr_debug("expire age %lu jiffies %lu\n",
 140                                  f->ageing_timer, jiffies);
 141                         fdb_delete(f);
 142                 } else {
 143                         mod_timer(&br->gc_timer, expires);
 144                         break;
 145                 }
 146         }
 147         write_unlock_bh(&br->hash_lock);
 148 }
 149
 150 void br_fdb_delete_by_port(struct net_bridge *br, struct net_bridge_port *p)
 151 {
 152         int i;
 153
 154         write_lock_bh(&br->hash_lock);
 155         for (i = 0; i < BR_HASH_SIZE; i++) {
 156                 struct hlist_node *h, *g;
 157
 158                 hlist_for_each_safe(h, g, &br->hash[i]) {
 159                         struct net_bridge_fdb_entry *f
 160                                 = hlist_entry(h, struct net_bridge_fdb_entry, hlist);
 161                         if (f->dst != p)
 162                                 continue;
 163
 164                         /*
 165                          * if multiple ports all have the same device address
 166                          * then when one port is deleted, assign
 167                          * the local entry to other port
 168                          */
 169                         if (f->is_local) {
 170                                 struct net_bridge_port *op;
 171                                 list_for_each_entry(op, &br->port_list, list) {
 172                                         if (op != p &&
 173                                             !memcmp(op->dev->dev_addr,
 174                                                     f->addr.addr, ETH_ALEN)) {
 175                                                 f->dst = op;
 176                                                 goto skip_delete;
 177                                         }
 178                                 }
 179                         }
 180
 181                         fdb_delete(f);
 182                 skip_delete: ;
 183                 }
 184         }
 185         write_unlock_bh(&br->hash_lock);
 186 }
 187
 188 struct net_bridge_fdb_entry *br_fdb_get(struct net_bridge *br, unsigned char *addr)
 189 {
 190         struct hlist_node *h;
 191
 192         read_lock_bh(&br->hash_lock);
 193
 194         hlist_for_each(h, &br->hash[br_mac_hash(addr)]) {
 195                 struct net_bridge_fdb_entry *fdb
 196                         = hlist_entry(h, struct net_bridge_fdb_entry, hlist);
 197
 198                 if (!memcmp(fdb->addr.addr, addr, ETH_ALEN)) {
 199                         if (has_expired(br, fdb))
 200                                 goto ret_null;
 201
 202                         atomic_inc(&fdb->use_count);
 203                         read_unlock_bh(&br->hash_lock);
 204                         return fdb;
 205                 }
 206         }
 207  ret_null:
 208         read_unlock_bh(&br->hash_lock);
 209         return NULL;
 210 }
 211
 212 void br_fdb_put(struct net_bridge_fdb_entry *ent)
 213 {
 214         if (atomic_dec_and_test(&ent->use_count))
 215                 kmem_cache_free(br_fdb_cache, ent);
 216 }
 217
 218 /*
 219  * Fill buffer with forwarding table records in
 220  * the API format.
 221  */
 222 int br_fdb_fillbuf(struct net_bridge *br, void *buf,
 223                    unsigned long maxnum, unsigned long skip)
 224 {
 225         struct __fdb_entry *fe = buf;
 226         int i, num = 0;
 227         struct hlist_node *h;
 228         struct net_bridge_fdb_entry *f;
 229
 230         memset(buf, 0, maxnum*sizeof(struct __fdb_entry));
 231
 232         read_lock_bh(&br->hash_lock);
 233         for (i = 0; i < BR_HASH_SIZE; i++) {
 234                 hlist_for_each_entry(f, h, &br->hash[i], hlist) {
 235                         if (num >= maxnum)
 236                                 goto out;
 237
 238                         if (has_expired(br, f))
 239                                 continue;
 240
 241                         if (skip) {
 242                                 --skip;
 243                                 continue;
 244                         }
 245
 246                         /* convert from internal format to API */
 247                         memcpy(fe->mac_addr, f->addr.addr, ETH_ALEN);
 248                         fe->port_no = f->dst->port_no;
 249                         fe->is_local = f->is_local;
 250                         if (!f->is_static)
 251                                 fe->ageing_timer_value = jiffies_to_clock_t(jiffies - f->ageing_timer);
 252                         ++fe;
 253                         ++num;
 254                 }
 255         }
 256
 257  out:
 258         read_unlock_bh(&br->hash_lock);
 259
 260         return num;
 261 }
 262
 263 static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
 264                   const unsigned char *addr, int is_local)
 265 {
 266         struct hlist_node *h;
 267         struct net_bridge_fdb_entry *fdb;
 268         int hash = br_mac_hash(addr);
 269
 270         if (!is_valid_ether_addr(addr))
 271                 return -EADDRNOTAVAIL;
 272
 273         hlist_for_each_entry(fdb, h, &br->hash[hash], hlist) {
 274                 if (!memcmp(fdb->addr.addr, addr, ETH_ALEN)) {
 275                         /* attempt to update an entry for a local interface */
 276                         if (fdb->is_local) {
 277                                 /* it is okay to have multiple ports with same
 278                                  * address, just don't allow to be spoofed.
 279                                  */
 280                                 if (is_local)
 281                                         return 0;
 282
 283                                 if (net_ratelimit())
 284                                         printk(KERN_WARNING "%s: received packet with "
 285                                                " own address as source address\n",
 286                                                source->dev->name);
 287                                 return -EEXIST;
 288                         }
 289
 290                         if (is_local) {
 291                                 printk(KERN_WARNING "%s adding interface with same address "
 292                                        "as a received packet\n",
 293                                        source->dev->name);
 294                                 goto update;
 295                         }
 296
 297                         if (fdb->is_static)
 298                                 return 0;
 299
 300                         /* move to end of age list */
 301                         list_del(&fdb->age_list);
 302                         goto update;
 303                 }
 304         }
 305
 306         fdb = kmem_cache_alloc(br_fdb_cache, GFP_ATOMIC);
 307         if (!fdb)
 308                 return ENOMEM;
 309
 310         memcpy(fdb->addr.addr, addr, ETH_ALEN);
 311         atomic_set(&fdb->use_count, 1);
 312         hlist_add_head(&fdb->hlist, &br->hash[hash]);
 313
 314         if (!timer_pending(&br->gc_timer)) {
 315                 br->gc_timer.expires = jiffies + hold_time(br);
 316                 add_timer(&br->gc_timer);
 317         }
 318
 319  update:
 320         fdb->dst = source;
 321         fdb->is_local = is_local;
 322         fdb->is_static = is_local;
 323         fdb->ageing_timer = jiffies;
 324         if (!is_local)
 325                 list_add_tail(&fdb->age_list, &br->age_list);
 326
 327         return 0;
 328 }
 329
 330 int br_fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
 331                   const unsigned char *addr, int is_local)
 332 {
 333         int ret;
 334
 335         write_lock_bh(&br->hash_lock);
 336         ret = fdb_insert(br, source, addr, is_local);
 337         write_unlock_bh(&br->hash_lock);
 338         return ret;
 339 }