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 inline void fdb_delete(struct net_bridge_fdb_entry *f)
  75 {
  76         hlist_del_rcu(&f->hlist);
  77         br_fdb_put(f);
  78 }
  79
  80 void br_fdb_changeaddr(struct net_bridge_port *p, const unsigned char *newaddr)
  81 {
  82         struct net_bridge *br = p->br;
  83         int i;
  84
  85         spin_lock_bh(&br->hash_lock);
  86
  87         /* Search all chains since old address/hash is unknown */
  88         for (i = 0; i < BR_HASH_SIZE; i++) {
  89                 struct hlist_node *h;
  90                 hlist_for_each(h, &br->hash[i]) {
  91                         struct net_bridge_fdb_entry *f;
  92
  93                         f = hlist_entry(h, struct net_bridge_fdb_entry, hlist);
  94                         if (f->dst == p && f->is_local) {
  95                                 /* maybe another port has same hw addr? */
  96                                 struct net_bridge_port *op;
  97                                 list_for_each_entry(op, &br->port_list, list) {
  98                                         if (op != p &&
  99                                             !compare_ether_addr(op->dev->dev_addr,
 100                                                                 f->addr.addr)) {
 101                                                 f->dst = op;
 102                                                 goto insert;
 103                                         }
 104                                 }
 105
 106                                 /* delete old one */
 107                                 fdb_delete(f);
 108                                 goto insert;
 109                         }
 110                 }
 111         }
 112  insert:
 113         /* insert new address,  may fail if invalid address or dup. */
 114         fdb_insert(br, p, newaddr);
 115
 116         spin_unlock_bh(&br->hash_lock);
 117 }
 118
 119 void br_fdb_cleanup(unsigned long _data)
 120 {
 121         struct net_bridge *br = (struct net_bridge *)_data;
 122         unsigned long delay = hold_time(br);
 123         unsigned long next_timer = jiffies + br->forward_delay;
 124         int i;
 125
 126         spin_lock_bh(&br->hash_lock);
 127         for (i = 0; i < BR_HASH_SIZE; i++) {
 128                 struct net_bridge_fdb_entry *f;
 129                 struct hlist_node *h, *n;
 130
 131                 hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
 132                         unsigned long this_timer;
 133                         if (f->is_static)
 134                                 continue;
 135                         this_timer = f->ageing_timer + delay;
 136                         if (time_before_eq(this_timer, jiffies))
 137                                 fdb_delete(f);
 138                         else if (time_before(this_timer, next_timer))
 139                                 next_timer = this_timer;
 140                 }
 141         }
 142         spin_unlock_bh(&br->hash_lock);
 143
 144         /* Add HZ/4 to ensure we round the jiffies upwards to be after the next
 145          * timer, otherwise we might round down and will have no-op run. */
 146         mod_timer(&br->gc_timer, round_jiffies(next_timer + HZ/4));
 147 }
 148
 149 /* Completely flush all dynamic entries in forwarding database.*/
 150 void br_fdb_flush(struct net_bridge *br)
 151 {
 152         int i;
 153
 154         spin_lock_bh(&br->hash_lock);
 155         for (i = 0; i < BR_HASH_SIZE; i++) {
 156                 struct net_bridge_fdb_entry *f;
 157                 struct hlist_node *h, *n;
 158                 hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
 159                         if (!f->is_static)
 160                                 fdb_delete(f);
 161                 }
 162         }
 163         spin_unlock_bh(&br->hash_lock);
 164 }
 165
 166 /* Flush all entries refering to a specific port.
 167  * if do_all is set also flush static entries
 168  */
 169 void br_fdb_delete_by_port(struct net_bridge *br,
 170                            const struct net_bridge_port *p,
 171                            int do_all)
 172 {
 173         int i;
 174
 175         spin_lock_bh(&br->hash_lock);
 176         for (i = 0; i < BR_HASH_SIZE; i++) {
 177                 struct hlist_node *h, *g;
 178
 179                 hlist_for_each_safe(h, g, &br->hash[i]) {
 180                         struct net_bridge_fdb_entry *f
 181                                 = hlist_entry(h, struct net_bridge_fdb_entry, hlist);
 182                         if (f->dst != p)
 183                                 continue;
 184
 185                         if (f->is_static && !do_all)
 186                                 continue;
 187                         /*
 188                          * if multiple ports all have the same device address
 189                          * then when one port is deleted, assign
 190                          * the local entry to other port
 191                          */
 192                         if (f->is_local) {
 193                                 struct net_bridge_port *op;
 194                                 list_for_each_entry(op, &br->port_list, list) {
 195                                         if (op != p &&
 196                                             !compare_ether_addr(op->dev->dev_addr,
 197                                                                 f->addr.addr)) {
 198                                                 f->dst = op;
 199                                                 goto skip_delete;
 200                                         }
 201                                 }
 202                         }
 203
 204                         fdb_delete(f);
 205                 skip_delete: ;
 206                 }
 207         }
 208         spin_unlock_bh(&br->hash_lock);
 209 }
 210
 211 /* No locking or refcounting, assumes caller has no preempt (rcu_read_lock) */
 212 struct net_bridge_fdb_entry *__br_fdb_get(struct net_bridge *br,
 213                                           const unsigned char *addr)
 214 {
 215         struct hlist_node *h;
 216         struct net_bridge_fdb_entry *fdb;
 217
 218         hlist_for_each_entry_rcu(fdb, h, &br->hash[br_mac_hash(addr)], hlist) {
 219                 if (!compare_ether_addr(fdb->addr.addr, addr)) {
 220                         if (unlikely(has_expired(br, fdb)))
 221                                 break;
 222                         return fdb;
 223                 }
 224         }
 225
 226         return NULL;
 227 }
 228
 229 /* Interface used by ATM hook that keeps a ref count */
 230 struct net_bridge_fdb_entry *br_fdb_get(struct net_bridge *br,
 231                                         unsigned char *addr)
 232 {
 233         struct net_bridge_fdb_entry *fdb;
 234
 235         rcu_read_lock();
 236         fdb = __br_fdb_get(br, addr);
 237         if (fdb && !atomic_inc_not_zero(&fdb->use_count))
 238                 fdb = NULL;
 239         rcu_read_unlock();
 240         return fdb;
 241 }
 242
 243 static void fdb_rcu_free(struct rcu_head *head)
 244 {
 245         struct net_bridge_fdb_entry *ent
 246                 = container_of(head, struct net_bridge_fdb_entry, rcu);
 247         kmem_cache_free(br_fdb_cache, ent);
 248 }
 249
 250 /* Set entry up for deletion with RCU  */
 251 void br_fdb_put(struct net_bridge_fdb_entry *ent)
 252 {
 253         if (atomic_dec_and_test(&ent->use_count))
 254                 call_rcu(&ent->rcu, fdb_rcu_free);
 255 }
 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                 atomic_set(&fdb->use_count, 1);
 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
 357                 printk(KERN_WARNING "%s adding interface with same address "
 358                        "as a received packet\n",
 359                        source->dev->name);
 360                 fdb_delete(fdb);
 361         }
 362
 363         if (!fdb_create(head, source, addr, 1))
 364                 return -ENOMEM;
 365
 366         return 0;
 367 }
 368
 369 int br_fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
 370                   const unsigned char *addr)
 371 {
 372         int ret;
 373
 374         spin_lock_bh(&br->hash_lock);
 375         ret = fdb_insert(br, source, addr);
 376         spin_unlock_bh(&br->hash_lock);
 377         return ret;
 378 }
 379
 380 void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
 381                    const unsigned char *addr)
 382 {
 383         struct hlist_head *head = &br->hash[br_mac_hash(addr)];
 384         struct net_bridge_fdb_entry *fdb;
 385
 386         /* some users want to always flood. */
 387         if (hold_time(br) == 0)
 388                 return;
 389
 390         /* ignore packets unless we are using this port */
 391         if (!(source->state == BR_STATE_LEARNING ||
 392               source->state == BR_STATE_FORWARDING))
 393                 return;
 394
 395         fdb = fdb_find(head, addr);
 396         if (likely(fdb)) {
 397                 /* attempt to update an entry for a local interface */
 398                 if (unlikely(fdb->is_local)) {
 399                         if (net_ratelimit())
 400                                 printk(KERN_WARNING "%s: received packet with "
 401                                        " own address as source address\n",
 402                                        source->dev->name);
 403                 } else {
 404                         /* fastpath: update of existing entry */
 405                         fdb->dst = source;
 406                         fdb->ageing_timer = jiffies;
 407                 }
 408         } else {
 409                 spin_lock(&br->hash_lock);
 410                 if (!fdb_find(head, addr))
 411                         fdb_create(head, source, addr, 0);
 412                 /* else  we lose race and someone else inserts
 413                  * it first, don't bother updating
 414                  */
 415                 spin_unlock(&br->hash_lock);
 416         }
 417 }