LXR linux/net/bridge/br

   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 <linux/jhash.h>
  23#include <linux/random.h>
  24#include <asm/atomic.h>
  25#include <asm/unaligned.h>
  26#include "br_private.h"
  27
  28static struct kmem_cache *br_fdb_cache __read_mostly;
  29static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
  30                      const unsigned char *addr);
  31
  32static u32 fdb_salt __read_mostly;
  33
  34int __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
  47void 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 */
  56static inline unsigned long hold_time(const struct net_bridge *br)
  57{
  58        return br->topology_change ? br->forward_delay : br->ageing_time;
  59}
  60
  61static 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
  68static 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
  75static inline void fdb_delete(struct net_bridge_fdb_entry *f)
  76{
  77        hlist_del_rcu(&f->hlist);
  78        br_fdb_put(f);
  79}
  80
  81void br_fdb_changeaddr(struct net_bridge_port *p, const unsigned char *newaddr)
  82{
  83        struct net_bridge *br = p->br;
  84        int i;
  85
  86        spin_lock_bh(&br->hash_lock);
  87
  88        /* Search all chains since old address/hash is unknown */
  89        for (i = 0; i < BR_HASH_SIZE; i++) {
  90                struct hlist_node *h;
  91                hlist_for_each(h, &br->hash[i]) {
  92                        struct net_bridge_fdb_entry *f;
  93
  94                        f = hlist_entry(h, struct net_bridge_fdb_entry, hlist);
  95                        if (f->dst == p && f->is_local) {
  96                                /* maybe another port has same hw addr? */
  97                                struct net_bridge_port *op;
  98                                list_for_each_entry(op, &br->port_list, list) {
  99                                        if (op != p &&
 100                                            !compare_ether_addr(op->dev->dev_addr,
 101                                                                f->addr.addr)) {
 102                                                f->dst = op;
 103                                                goto insert;
 104                                        }
 105                                }
 106
 107                                /* delete old one */
 108                                fdb_delete(f);
 109                                goto insert;
 110                        }
 111                }
 112        }
 113 insert:
 114        /* insert new address,  may fail if invalid address or dup. */
 115        fdb_insert(br, p, newaddr);
 116
 117        spin_unlock_bh(&br->hash_lock);
 118}
 119
 120void br_fdb_cleanup(unsigned long _data)
 121{
 122        struct net_bridge *br = (struct net_bridge *)_data;
 123        unsigned long delay = hold_time(br);
 124        unsigned long next_timer = jiffies + br->forward_delay;
 125        int i;
 126
 127        spin_lock_bh(&br->hash_lock);
 128        for (i = 0; i < BR_HASH_SIZE; i++) {
 129                struct net_bridge_fdb_entry *f;
 130                struct hlist_node *h, *n;
 131
 132                hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
 133                        unsigned long this_timer;
 134                        if (f->is_static)
 135                                continue;
 136                        this_timer = f->ageing_timer + delay;
 137                        if (time_before_eq(this_timer, jiffies))
 138                                fdb_delete(f);
 139                        else if (this_timer < next_timer)
 140                                next_timer = this_timer;
 141                }
 142        }
 143        spin_unlock_bh(&br->hash_lock);
 144
 145        /* Add HZ/4 to ensure we round the jiffies upwards to be after the next
 146         * timer, otherwise we might round down and will have no-op run. */
 147        mod_timer(&br->gc_timer, round_jiffies(next_timer + HZ/4));
 148}
 149
 150/* Completely flush all dynamic entries in forwarding database.*/
 151void br_fdb_flush(struct net_bridge *br)
 152{
 153        int i;
 154
 155        spin_lock_bh(&br->hash_lock);
 156        for (i = 0; i < BR_HASH_SIZE; i++) {
 157                struct net_bridge_fdb_entry *f;
 158                struct hlist_node *h, *n;
 159                hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
 160                        if (!f->is_static)
 161                                fdb_delete(f);
 162                }
 163        }
 164        spin_unlock_bh(&br->hash_lock);
 165}
 166
 167/* Flush all entries refering to a specific port.
 168 * if do_all is set also flush static entries
 169 */
 170void br_fdb_delete_by_port(struct net_bridge *br,
 171                           const struct net_bridge_port *p,
 172                           int do_all)
 173{
 174        int i;
 175
 176        spin_lock_bh(&br->hash_lock);
 177        for (i = 0; i < BR_HASH_SIZE; i++) {
 178                struct hlist_node *h, *g;
 179
 180                hlist_for_each_safe(h, g, &br->hash[i]) {
 181                        struct net_bridge_fdb_entry *f
 182                                = hlist_entry(h, struct net_bridge_fdb_entry, hlist);
 183                        if (f->dst != p)
 184                                continue;
 185
 186                        if (f->is_static && !do_all)
 187                                continue;
 188                        /*
 189                         * if multiple ports all have the same device address
 190                         * then when one port is deleted, assign
 191                         * the local entry to other port
 192                         */
 193                        if (f->is_local) {
 194                                struct net_bridge_port *op;
 195                                list_for_each_entry(op, &br->port_list, list) {
 196                                        if (op != p &&
 197                                            !compare_ether_addr(op->dev->dev_addr,
 198                                                                f->addr.addr)) {
 199                                                f->dst = op;
 200                                                goto skip_delete;
 201                                        }
 202                                }
 203                        }
 204
 205                        fdb_delete(f);
 206                skip_delete: ;
 207                }
 208        }
 209        spin_unlock_bh(&br->hash_lock);
 210}
 211
 212/* No locking or refcounting, assumes caller has no preempt (rcu_read_lock) */
 213struct net_bridge_fdb_entry *__br_fdb_get(struct net_bridge *br,
 214                                          const unsigned char *addr)
 215{
 216        struct hlist_node *h;
 217        struct net_bridge_fdb_entry *fdb;
 218
 219        hlist_for_each_entry_rcu(fdb, h, &br->hash[br_mac_hash(addr)], hlist) {
 220                if (!compare_ether_addr(fdb->addr.addr, addr)) {
 221                        if (unlikely(has_expired(br, fdb)))
 222                                break;
 223                        return fdb;
 224                }
 225        }
 226
 227        return NULL;
 228}
 229
 230/* Interface used by ATM hook that keeps a ref count */
 231struct net_bridge_fdb_entry *br_fdb_get(struct net_bridge *br,
 232                                        unsigned char *addr)
 233{
 234        struct net_bridge_fdb_entry *fdb;
 235
 236        rcu_read_lock();
 237        fdb = __br_fdb_get(br, addr);
 238        if (fdb && !atomic_inc_not_zero(&fdb->use_count))
 239                fdb = NULL;
 240        rcu_read_unlock();
 241        return fdb;
 242}
 243
 244static void fdb_rcu_free(struct rcu_head *head)
 245{
 246        struct net_bridge_fdb_entry *ent
 247                = container_of(head, struct net_bridge_fdb_entry, rcu);
 248        kmem_cache_free(br_fdb_cache, ent);
 249}
 250
 251/* Set entry up for deletion with RCU  */
 252void br_fdb_put(struct net_bridge_fdb_entry *ent)
 253{
 254        if (atomic_dec_and_test(&ent->use_count))
 255                call_rcu(&ent->rcu, fdb_rcu_free);
 256}
 257
 258/*
 259 * Fill buffer with forwarding table records in
 260 * the API format.
 261 */
 262int br_fdb_fillbuf(struct net_bridge *br, void *buf,
 263                   unsigned long maxnum, unsigned long skip)
 264{
 265        struct __fdb_entry *fe = buf;
 266        int i, num = 0;
 267        struct hlist_node *h;
 268        struct net_bridge_fdb_entry *f;
 269
 270        memset(buf, 0, maxnum*sizeof(struct __fdb_entry));
 271
 272        rcu_read_lock();
 273        for (i = 0; i < BR_HASH_SIZE; i++) {
 274                hlist_for_each_entry_rcu(f, h, &br->hash[i], hlist) {
 275                        if (num >= maxnum)
 276                                goto out;
 277
 278                        if (has_expired(br, f))
 279                                continue;
 280
 281                        if (skip) {
 282                                --skip;
 283                                continue;
 284                        }
 285
 286                        /* convert from internal format to API */
 287                        memcpy(fe->mac_addr, f->addr.addr, ETH_ALEN);
 288                        fe->port_no = f->dst->port_no;
 289                        fe->is_local = f->is_local;
 290                        if (!f->is_static)
 291                                fe->ageing_timer_value = jiffies_to_clock_t(jiffies - f->ageing_timer);
 292                        ++fe;
 293                        ++num;
 294                }
 295        }
 296
 297 out:
 298        rcu_read_unlock();
 299
 300        return num;
 301}
 302
 303static inline struct net_bridge_fdb_entry *fdb_find(struct hlist_head *head,
 304                                                    const unsigned char *addr)
 305{
 306        struct hlist_node *h;
 307        struct net_bridge_fdb_entry *fdb;
 308
 309        hlist_for_each_entry_rcu(fdb, h, head, hlist) {
 310                if (!compare_ether_addr(fdb->addr.addr, addr))
 311                        return fdb;
 312        }
 313        return NULL;
 314}
 315
 316static struct net_bridge_fdb_entry *fdb_create(struct hlist_head *head,
 317                                               struct net_bridge_port *source,
 318                                               const unsigned char *addr,
 319                                               int is_local)
 320{
 321        struct net_bridge_fdb_entry *fdb;
 322
 323        fdb = kmem_cache_alloc(br_fdb_cache, GFP_ATOMIC);
 324        if (fdb) {
 325                memcpy(fdb->addr.addr, addr, ETH_ALEN);
 326                atomic_set(&fdb->use_count, 1);
 327                hlist_add_head_rcu(&fdb->hlist, head);
 328
 329                fdb->dst = source;
 330                fdb->is_local = is_local;
 331                fdb->is_static = is_local;
 332                fdb->ageing_timer = jiffies;
 333        }
 334        return fdb;
 335}
 336
 337static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
 338                  const unsigned char *addr)
 339{
 340        struct hlist_head *head = &br->hash[br_mac_hash(addr)];
 341        struct net_bridge_fdb_entry *fdb;
 342
 343        if (!is_valid_ether_addr(addr))
 344                return -EINVAL;
 345
 346        fdb = fdb_find(head, addr);
 347        if (fdb) {
 348                /* it is okay to have multiple ports with same
 349                 * address, just use the first one.
 350                 */
 351                if (fdb->is_local)
 352                        return 0;
 353
 354                printk(KERN_WARNING "%s adding interface 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
 366int 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
 377void 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                                printk(KERN_WARNING "%s: received packet 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}
 415