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