LXR linux/net/bridge/br

   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
  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 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
  82static 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
  88void 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
 127void 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.*/
 156void 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 referring to a specific port.
 173 * if do_all is set also flush static entries
 174 */
 175void 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 rcu_read_lock */
 218struct 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 */
 238int br_fdb_test_addr(struct net_device *dev, unsigned char *addr)
 239{
 240        struct net_bridge_fdb_entry *fdb;
 241        struct net_bridge_port *port;
 242        int ret;
 243
 244        rcu_read_lock();
 245        port = br_port_get_rcu(dev);
 246        if (!port)
 247                ret = 0;
 248        else {
 249                fdb = __br_fdb_get(port->br, addr);
 250                ret = fdb && fdb->dst->dev != dev &&
 251                        fdb->dst->state == BR_STATE_FORWARDING;
 252        }
 253        rcu_read_unlock();
 254
 255        return ret;
 256}
 257#endif /* CONFIG_ATM_LANE */
 258
 259/*
 260 * Fill buffer with forwarding table records in
 261 * the API format.
 262 */
 263int br_fdb_fillbuf(struct net_bridge *br, void *buf,
 264                   unsigned long maxnum, unsigned long skip)
 265{
 266        struct __fdb_entry *fe = buf;
 267        int i, num = 0;
 268        struct hlist_node *h;
 269        struct net_bridge_fdb_entry *f;
 270
 271        memset(buf, 0, maxnum*sizeof(struct __fdb_entry));
 272
 273        rcu_read_lock();
 274        for (i = 0; i < BR_HASH_SIZE; i++) {
 275                hlist_for_each_entry_rcu(f, h, &br->hash[i], hlist) {
 276                        if (num >= maxnum)
 277                                goto out;
 278
 279                        if (has_expired(br, f))
 280                                continue;
 281
 282                        if (skip) {
 283                                --skip;
 284                                continue;
 285                        }
 286
 287                        /* convert from internal format to API */
 288                        memcpy(fe->mac_addr, f->addr.addr, ETH_ALEN);
 289
 290                        /* due to ABI compat need to split into hi/lo */
 291                        fe->port_no = f->dst->port_no;
 292                        fe->port_hi = f->dst->port_no >> 8;
 293
 294                        fe->is_local = f->is_local;
 295                        if (!f->is_static)
 296                                fe->ageing_timer_value = jiffies_to_clock_t(jiffies - f->ageing_timer);
 297                        ++fe;
 298                        ++num;
 299                }
 300        }
 301
 302 out:
 303        rcu_read_unlock();
 304
 305        return num;
 306}
 307
 308static inline struct net_bridge_fdb_entry *fdb_find(struct hlist_head *head,
 309                                                    const unsigned char *addr)
 310{
 311        struct hlist_node *h;
 312        struct net_bridge_fdb_entry *fdb;
 313
 314        hlist_for_each_entry_rcu(fdb, h, head, hlist) {
 315                if (!compare_ether_addr(fdb->addr.addr, addr))
 316                        return fdb;
 317        }
 318        return NULL;
 319}
 320
 321static struct net_bridge_fdb_entry *fdb_create(struct hlist_head *head,
 322                                               struct net_bridge_port *source,
 323                                               const unsigned char *addr,
 324                                               int is_local)
 325{
 326        struct net_bridge_fdb_entry *fdb;
 327
 328        fdb = kmem_cache_alloc(br_fdb_cache, GFP_ATOMIC);
 329        if (fdb) {
 330                memcpy(fdb->addr.addr, addr, ETH_ALEN);
 331                fdb->dst = source;
 332                fdb->is_local = is_local;
 333                fdb->is_static = is_local;
 334                fdb->ageing_timer = jiffies;
 335
 336                hlist_add_head_rcu(&fdb->hlist, head);
 337        }
 338        return fdb;
 339}
 340
 341static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
 342                  const unsigned char *addr)
 343{
 344        struct hlist_head *head = &br->hash[br_mac_hash(addr)];
 345        struct net_bridge_fdb_entry *fdb;
 346
 347        if (!is_valid_ether_addr(addr))
 348                return -EINVAL;
 349
 350        fdb = fdb_find(head, addr);
 351        if (fdb) {
 352                /* it is okay to have multiple ports with same
 353                 * address, just use the first one.
 354                 */
 355                if (fdb->is_local)
 356                        return 0;
 357                br_warn(br, "adding interface %s 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
 369int 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
 380void 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                                br_warn(br, "received packet on %s 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}
 418