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 <linux/slab.h>
  24 #include <asm/atomic.h>
  25 #include <asm/unaligned.h>
  26 #include "br_private.h"
  27
  28 static struct kmem_cache *br_fdb_cache __read_mostly;
  29 static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
  30                       const unsigned char *addr);
  31
  32 static u32 fdb_salt __read_mostly;
  33
  34 int __init br_fdb_init(void)
  35 {
  36         br_fdb_cache = kmem_cache_create("bridge_fdb_cache",
  37                                          sizeof(struct net_bridge_fdb_entry),
  38                                          0,
  39                                          SLAB_HWCACHE_ALIGN, NULL);
  40         if (!br_fdb_cache)
  41                 return -ENOMEM;
  42
  43         get_random_bytes(&fdb_salt, sizeof(fdb_salt));
  44         return 0;
  45 }
  46
  47 void br_fdb_fini(void)
  48 {
  49         kmem_cache_destroy(br_fdb_cache);
  50 }
  51
  52
  53 /* if topology_changing then use forward_delay (default 15 sec)
  54  * otherwise keep longer (default 5 minutes)
  55  */
  56 static inline unsigned long hold_time(const struct net_bridge *br)
  57 {
  58         return br->topology_change ? br->forward_delay : br->ageing_time;
  59 }
  60
  61 static inline int has_expired(const struct net_bridge *br,
  62                                   const struct net_bridge_fdb_entry *fdb)
  63 {
  64         return !fdb->is_static &&
  65                 time_before_eq(fdb->ageing_timer + hold_time(br), jiffies);
  66 }
  67
  68 static inline int br_mac_hash(const unsigned char *mac)
  69 {
  70         /* use 1 byte of OUI cnd 3 bytes of NIC */
  71         u32 key = get_unaligned((u32 *)(mac + 2));
  72         return jhash_1word(key, fdb_salt) & (BR_HASH_SIZE - 1);
  73 }
  74
  75 static void fdb_rcu_free(struct rcu_head *head)
  76 {
  77         struct net_bridge_fdb_entry *ent
  78                 = container_of(head, struct net_bridge_fdb_entry, rcu);
  79         kmem_cache_free(br_fdb_cache, ent);
  80 }
  81
  82 static inline void fdb_delete(struct net_bridge_fdb_entry *f)
  83 {
  84         hlist_del_rcu(&f->hlist);
  85         call_rcu(&f->rcu, fdb_rcu_free);
  86 }
  87
  88 void br_fdb_changeaddr(struct net_bridge_port *p, const unsigned char *newaddr)
  89 {
  90         struct net_bridge *br = p->br;
  91         int i;
  92
  93         spin_lock_bh(&br->hash_lock);
  94
  95         /* Search all chains since old address/hash is unknown */
  96         for (i = 0; i < BR_HASH_SIZE; i++) {
  97                 struct hlist_node *h;
  98                 hlist_for_each(h, &br->hash[i]) {
  99                         struct net_bridge_fdb_entry *f;
 100
 101                         f = hlist_entry(h, struct net_bridge_fdb_entry, hlist);
 102                         if (f->dst == p && f->is_local) {
 103                                 /* maybe another port has same hw addr? */
 104                                 struct net_bridge_port *op;
 105                                 list_for_each_entry(op, &br->port_list, list) {
 106                                         if (op != p &&
 107                                             !compare_ether_addr(op->dev->dev_addr,
 108                                                                 f->addr.addr)) {
 109                                                 f->dst = op;
 110                                                 goto insert;
 111                                         }
 112                                 }
 113
 114                                 /* delete old one */
 115                                 fdb_delete(f);
 116                                 goto insert;
 117                         }
 118                 }
 119         }
 120  insert:
 121         /* insert new address,  may fail if invalid address or dup. */
 122         fdb_insert(br, p, newaddr);
 123
 124         spin_unlock_bh(&br->hash_lock);
 125 }
 126
 127 void br_fdb_cleanup(unsigned long _data)
 128 {
 129         struct net_bridge *br = (struct net_bridge *)_data;
 130         unsigned long delay = hold_time(br);
 131         unsigned long next_timer = jiffies + br->ageing_time;
 132         int i;
 133
 134         spin_lock_bh(&br->hash_lock);
 135         for (i = 0; i < BR_HASH_SIZE; i++) {
 136                 struct net_bridge_fdb_entry *f;
 137                 struct hlist_node *h, *n;
 138
 139                 hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
 140                         unsigned long this_timer;
 141                         if (f->is_static)
 142                                 continue;
 143                         this_timer = f->ageing_timer + delay;
 144                         if (time_before_eq(this_timer, jiffies))
 145                                 fdb_delete(f);
 146                         else if (time_before(this_timer, next_timer))
 147                                 next_timer = this_timer;
 148                 }
 149         }
 150         spin_unlock_bh(&br->hash_lock);
 151
 152         mod_timer(&br->gc_timer, round_jiffies_up(next_timer));
 153 }
 154
 155 /* Completely flush all dynamic entries in forwarding database.*/
 156 void br_fdb_flush(struct net_bridge *br)
 157 {
 158         int i;
 159
 160         spin_lock_bh(&br->hash_lock);
 161         for (i = 0; i < BR_HASH_SIZE; i++) {
 162                 struct net_bridge_fdb_entry *f;
 163                 struct hlist_node *h, *n;
 164                 hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
 165                         if (!f->is_static)
 166                                 fdb_delete(f);
 167                 }
 168         }
 169         spin_unlock_bh(&br->hash_lock);
 170 }
 171
 172 /* Flush all entries refering to a specific port.
 173  * if do_all is set also flush static entries
 174  */
 175 void br_fdb_delete_by_port(struct net_bridge *br,
 176                            const struct net_bridge_port *p,
 177                            int do_all)
 178 {
 179         int i;
 180
 181         spin_lock_bh(&br->hash_lock);
 182         for (i = 0; i < BR_HASH_SIZE; i++) {
 183                 struct hlist_node *h, *g;
 184
 185                 hlist_for_each_safe(h, g, &br->hash[i]) {
 186                         struct net_bridge_fdb_entry *f
 187                                 = hlist_entry(h, struct net_bridge_fdb_entry, hlist);
 188                         if (f->dst != p)
 189                                 continue;
 190
 191                         if (f->is_static && !do_all)
 192                                 continue;
 193                         /*
 194                          * if multiple ports all have the same device address
 195                          * then when one port is deleted, assign
 196                          * the local entry to other port
 197                          */
 198                         if (f->is_local) {
 199                                 struct net_bridge_port *op;
 200                                 list_for_each_entry(op, &br->port_list, list) {
 201                                         if (op != p &&
 202                                             !compare_ether_addr(op->dev->dev_addr,
 203                                                                 f->addr.addr)) {
 204                                                 f->dst = op;
 205                                                 goto skip_delete;
 206                                         }
 207                                 }
 208                         }
 209
 210                         fdb_delete(f);
 211                 skip_delete: ;
 212                 }
 213         }
 214         spin_unlock_bh(&br->hash_lock);
 215 }
 216
 217 /* No locking or refcounting, assumes caller has no preempt (rcu_read_lock) */
 218 struct net_bridge_fdb_entry *__br_fdb_get(struct net_bridge *br,
 219                                           const unsigned char *addr)
 220 {
 221         struct hlist_node *h;
 222         struct net_bridge_fdb_entry *fdb;
 223
 224         hlist_for_each_entry_rcu(fdb, h, &br->hash[br_mac_hash(addr)], hlist) {
 225                 if (!compare_ether_addr(fdb->addr.addr, addr)) {
 226                         if (unlikely(has_expired(br, fdb)))
 227                                 break;
 228                         return fdb;
 229                 }
 230         }
 231
 232         return NULL;
 233 }
 234
 235 #if defined(CONFIG_ATM_LANE) || defined(CONFIG_ATM_LANE_MODULE)
 236 /* Interface used by ATM LANE hook to test
 237  * if an addr is on some other bridge port */
 238 int br_fdb_test_addr(struct net_device *dev, unsigned char *addr)
 239 {
 240         struct net_bridge_fdb_entry *fdb;
 241         int ret;
 242
 243         if (!dev->br_port)
 244                 return 0;
 245
 246         rcu_read_lock();
 247         fdb = __br_fdb_get(dev->br_port->br, addr);
 248         ret = fdb && fdb->dst->dev != dev &&
 249                 fdb->dst->state == BR_STATE_FORWARDING;
 250         rcu_read_unlock();
 251
 252         return ret;
 253 }
 254 #endif /* CONFIG_ATM_LANE */
 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                 hlist_add_head_rcu(&fdb->hlist, head);
 329
 330                 fdb->dst = source;
 331                 fdb->is_local = is_local;
 332                 fdb->is_static = is_local;
 333                 fdb->ageing_timer = jiffies;
 334         }
 335         return fdb;
 336 }
 337
 338 static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
 339                   const unsigned char *addr)
 340 {
 341         struct hlist_head *head = &br->hash[br_mac_hash(addr)];
 342         struct net_bridge_fdb_entry *fdb;
 343
 344         if (!is_valid_ether_addr(addr))
 345                 return -EINVAL;
 346
 347         fdb = fdb_find(head, addr);
 348         if (fdb) {
 349                 /* it is okay to have multiple ports with same
 350                  * address, just use the first one.
 351                  */
 352                 if (fdb->is_local)
 353                         return 0;
 354                 br_warn(br, "adding interface %s with same address "
 355                        "as a received packet\n",
 356                        source->dev->name);
 357                 fdb_delete(fdb);
 358         }
 359
 360         if (!fdb_create(head, source, addr, 1))
 361                 return -ENOMEM;
 362
 363         return 0;
 364 }
 365
 366 int br_fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
 367                   const unsigned char *addr)
 368 {
 369         int ret;
 370
 371         spin_lock_bh(&br->hash_lock);
 372         ret = fdb_insert(br, source, addr);
 373         spin_unlock_bh(&br->hash_lock);
 374         return ret;
 375 }
 376
 377 void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
 378                    const unsigned char *addr)
 379 {
 380         struct hlist_head *head = &br->hash[br_mac_hash(addr)];
 381         struct net_bridge_fdb_entry *fdb;
 382
 383         /* some users want to always flood. */
 384         if (hold_time(br) == 0)
 385                 return;
 386
 387         /* ignore packets unless we are using this port */
 388         if (!(source->state == BR_STATE_LEARNING ||
 389               source->state == BR_STATE_FORWARDING))
 390                 return;
 391
 392         fdb = fdb_find(head, addr);
 393         if (likely(fdb)) {
 394                 /* attempt to update an entry for a local interface */
 395                 if (unlikely(fdb->is_local)) {
 396                         if (net_ratelimit())
 397                                 br_warn(br, "received packet on %s with "
 398                                         "own address as source address\n",
 399                                         source->dev->name);
 400                 } else {
 401                         /* fastpath: update of existing entry */
 402                         fdb->dst = source;
 403                         fdb->ageing_timer = jiffies;
 404                 }
 405         } else {
 406                 spin_lock(&br->hash_lock);
 407                 if (!fdb_find(head, addr))
 408                         fdb_create(head, source, addr, 0);
 409                 /* else  we lose race and someone else inserts
 410                  * it first, don't bother updating
 411                  */
 412                 spin_unlock(&br->hash_lock);
 413         }
 414 }