linux/net/bridge/br_fdb.c
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   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 <linux/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);
  31static void fdb_notify(struct net_bridge *br,
  32                       const struct net_bridge_fdb_entry *, int);
  33
  34static u32 fdb_salt __read_mostly;
  35
  36int __init br_fdb_init(void)
  37{
  38        br_fdb_cache = kmem_cache_create("bridge_fdb_cache",
  39                                         sizeof(struct net_bridge_fdb_entry),
  40                                         0,
  41                                         SLAB_HWCACHE_ALIGN, NULL);
  42        if (!br_fdb_cache)
  43                return -ENOMEM;
  44
  45        get_random_bytes(&fdb_salt, sizeof(fdb_salt));
  46        return 0;
  47}
  48
  49void br_fdb_fini(void)
  50{
  51        kmem_cache_destroy(br_fdb_cache);
  52}
  53
  54
  55/* if topology_changing then use forward_delay (default 15 sec)
  56 * otherwise keep longer (default 5 minutes)
  57 */
  58static inline unsigned long hold_time(const struct net_bridge *br)
  59{
  60        return br->topology_change ? br->forward_delay : br->ageing_time;
  61}
  62
  63static inline int has_expired(const struct net_bridge *br,
  64                                  const struct net_bridge_fdb_entry *fdb)
  65{
  66        return !fdb->is_static &&
  67                time_before_eq(fdb->updated + hold_time(br), jiffies);
  68}
  69
  70static inline int br_mac_hash(const unsigned char *mac)
  71{
  72        /* use 1 byte of OUI cnd 3 bytes of NIC */
  73        u32 key = get_unaligned((u32 *)(mac + 2));
  74        return jhash_1word(key, fdb_salt) & (BR_HASH_SIZE - 1);
  75}
  76
  77static void fdb_rcu_free(struct rcu_head *head)
  78{
  79        struct net_bridge_fdb_entry *ent
  80                = container_of(head, struct net_bridge_fdb_entry, rcu);
  81        kmem_cache_free(br_fdb_cache, ent);
  82}
  83
  84static void fdb_delete(struct net_bridge *br, struct net_bridge_fdb_entry *f)
  85{
  86        hlist_del_rcu(&f->hlist);
  87        fdb_notify(br, f, RTM_DELNEIGH);
  88        call_rcu(&f->rcu, fdb_rcu_free);
  89}
  90
  91void br_fdb_changeaddr(struct net_bridge_port *p, const unsigned char *newaddr)
  92{
  93        struct net_bridge *br = p->br;
  94        int i;
  95
  96        spin_lock_bh(&br->hash_lock);
  97
  98        /* Search all chains since old address/hash is unknown */
  99        for (i = 0; i < BR_HASH_SIZE; i++) {
 100                struct hlist_node *h;
 101                hlist_for_each(h, &br->hash[i]) {
 102                        struct net_bridge_fdb_entry *f;
 103
 104                        f = hlist_entry(h, struct net_bridge_fdb_entry, hlist);
 105                        if (f->dst == p && f->is_local) {
 106                                /* maybe another port has same hw addr? */
 107                                struct net_bridge_port *op;
 108                                list_for_each_entry(op, &br->port_list, list) {
 109                                        if (op != p &&
 110                                            ether_addr_equal(op->dev->dev_addr,
 111                                                             f->addr.addr)) {
 112                                                f->dst = op;
 113                                                goto insert;
 114                                        }
 115                                }
 116
 117                                /* delete old one */
 118                                fdb_delete(br, f);
 119                                goto insert;
 120                        }
 121                }
 122        }
 123 insert:
 124        /* insert new address,  may fail if invalid address or dup. */
 125        fdb_insert(br, p, newaddr);
 126
 127        spin_unlock_bh(&br->hash_lock);
 128}
 129
 130void br_fdb_change_mac_address(struct net_bridge *br, const u8 *newaddr)
 131{
 132        struct net_bridge_fdb_entry *f;
 133
 134        /* If old entry was unassociated with any port, then delete it. */
 135        f = __br_fdb_get(br, br->dev->dev_addr);
 136        if (f && f->is_local && !f->dst)
 137                fdb_delete(br, f);
 138
 139        fdb_insert(br, NULL, newaddr);
 140}
 141
 142void br_fdb_cleanup(unsigned long _data)
 143{
 144        struct net_bridge *br = (struct net_bridge *)_data;
 145        unsigned long delay = hold_time(br);
 146        unsigned long next_timer = jiffies + br->ageing_time;
 147        int i;
 148
 149        spin_lock(&br->hash_lock);
 150        for (i = 0; i < BR_HASH_SIZE; i++) {
 151                struct net_bridge_fdb_entry *f;
 152                struct hlist_node *h, *n;
 153
 154                hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
 155                        unsigned long this_timer;
 156                        if (f->is_static)
 157                                continue;
 158                        this_timer = f->updated + delay;
 159                        if (time_before_eq(this_timer, jiffies))
 160                                fdb_delete(br, f);
 161                        else if (time_before(this_timer, next_timer))
 162                                next_timer = this_timer;
 163                }
 164        }
 165        spin_unlock(&br->hash_lock);
 166
 167        mod_timer(&br->gc_timer, round_jiffies_up(next_timer));
 168}
 169
 170/* Completely flush all dynamic entries in forwarding database.*/
 171void br_fdb_flush(struct net_bridge *br)
 172{
 173        int i;
 174
 175        spin_lock_bh(&br->hash_lock);
 176        for (i = 0; i < BR_HASH_SIZE; i++) {
 177                struct net_bridge_fdb_entry *f;
 178                struct hlist_node *h, *n;
 179                hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
 180                        if (!f->is_static)
 181                                fdb_delete(br, f);
 182                }
 183        }
 184        spin_unlock_bh(&br->hash_lock);
 185}
 186
 187/* Flush all entries referring to a specific port.
 188 * if do_all is set also flush static entries
 189 */
 190void br_fdb_delete_by_port(struct net_bridge *br,
 191                           const struct net_bridge_port *p,
 192                           int do_all)
 193{
 194        int i;
 195
 196        spin_lock_bh(&br->hash_lock);
 197        for (i = 0; i < BR_HASH_SIZE; i++) {
 198                struct hlist_node *h, *g;
 199
 200                hlist_for_each_safe(h, g, &br->hash[i]) {
 201                        struct net_bridge_fdb_entry *f
 202                                = hlist_entry(h, struct net_bridge_fdb_entry, hlist);
 203                        if (f->dst != p)
 204                                continue;
 205
 206                        if (f->is_static && !do_all)
 207                                continue;
 208                        /*
 209                         * if multiple ports all have the same device address
 210                         * then when one port is deleted, assign
 211                         * the local entry to other port
 212                         */
 213                        if (f->is_local) {
 214                                struct net_bridge_port *op;
 215                                list_for_each_entry(op, &br->port_list, list) {
 216                                        if (op != p &&
 217                                            ether_addr_equal(op->dev->dev_addr,
 218                                                             f->addr.addr)) {
 219                                                f->dst = op;
 220                                                goto skip_delete;
 221                                        }
 222                                }
 223                        }
 224
 225                        fdb_delete(br, f);
 226                skip_delete: ;
 227                }
 228        }
 229        spin_unlock_bh(&br->hash_lock);
 230}
 231
 232/* No locking or refcounting, assumes caller has rcu_read_lock */
 233struct net_bridge_fdb_entry *__br_fdb_get(struct net_bridge *br,
 234                                          const unsigned char *addr)
 235{
 236        struct hlist_node *h;
 237        struct net_bridge_fdb_entry *fdb;
 238
 239        hlist_for_each_entry_rcu(fdb, h, &br->hash[br_mac_hash(addr)], hlist) {
 240                if (ether_addr_equal(fdb->addr.addr, addr)) {
 241                        if (unlikely(has_expired(br, fdb)))
 242                                break;
 243                        return fdb;
 244                }
 245        }
 246
 247        return NULL;
 248}
 249
 250#if IS_ENABLED(CONFIG_ATM_LANE)
 251/* Interface used by ATM LANE hook to test
 252 * if an addr is on some other bridge port */
 253int br_fdb_test_addr(struct net_device *dev, unsigned char *addr)
 254{
 255        struct net_bridge_fdb_entry *fdb;
 256        struct net_bridge_port *port;
 257        int ret;
 258
 259        rcu_read_lock();
 260        port = br_port_get_rcu(dev);
 261        if (!port)
 262                ret = 0;
 263        else {
 264                fdb = __br_fdb_get(port->br, addr);
 265                ret = fdb && fdb->dst && fdb->dst->dev != dev &&
 266                        fdb->dst->state == BR_STATE_FORWARDING;
 267        }
 268        rcu_read_unlock();
 269
 270        return ret;
 271}
 272#endif /* CONFIG_ATM_LANE */
 273
 274/*
 275 * Fill buffer with forwarding table records in
 276 * the API format.
 277 */
 278int br_fdb_fillbuf(struct net_bridge *br, void *buf,
 279                   unsigned long maxnum, unsigned long skip)
 280{
 281        struct __fdb_entry *fe = buf;
 282        int i, num = 0;
 283        struct hlist_node *h;
 284        struct net_bridge_fdb_entry *f;
 285
 286        memset(buf, 0, maxnum*sizeof(struct __fdb_entry));
 287
 288        rcu_read_lock();
 289        for (i = 0; i < BR_HASH_SIZE; i++) {
 290                hlist_for_each_entry_rcu(f, h, &br->hash[i], hlist) {
 291                        if (num >= maxnum)
 292                                goto out;
 293
 294                        if (has_expired(br, f))
 295                                continue;
 296
 297                        /* ignore pseudo entry for local MAC address */
 298                        if (!f->dst)
 299                                continue;
 300
 301                        if (skip) {
 302                                --skip;
 303                                continue;
 304                        }
 305
 306                        /* convert from internal format to API */
 307                        memcpy(fe->mac_addr, f->addr.addr, ETH_ALEN);
 308
 309                        /* due to ABI compat need to split into hi/lo */
 310                        fe->port_no = f->dst->port_no;
 311                        fe->port_hi = f->dst->port_no >> 8;
 312
 313                        fe->is_local = f->is_local;
 314                        if (!f->is_static)
 315                                fe->ageing_timer_value = jiffies_to_clock_t(jiffies - f->updated);
 316                        ++fe;
 317                        ++num;
 318                }
 319        }
 320
 321 out:
 322        rcu_read_unlock();
 323
 324        return num;
 325}
 326
 327static struct net_bridge_fdb_entry *fdb_find(struct hlist_head *head,
 328                                             const unsigned char *addr)
 329{
 330        struct hlist_node *h;
 331        struct net_bridge_fdb_entry *fdb;
 332
 333        hlist_for_each_entry(fdb, h, head, hlist) {
 334                if (ether_addr_equal(fdb->addr.addr, addr))
 335                        return fdb;
 336        }
 337        return NULL;
 338}
 339
 340static struct net_bridge_fdb_entry *fdb_find_rcu(struct hlist_head *head,
 341                                                 const unsigned char *addr)
 342{
 343        struct hlist_node *h;
 344        struct net_bridge_fdb_entry *fdb;
 345
 346        hlist_for_each_entry_rcu(fdb, h, head, hlist) {
 347                if (ether_addr_equal(fdb->addr.addr, addr))
 348                        return fdb;
 349        }
 350        return NULL;
 351}
 352
 353static struct net_bridge_fdb_entry *fdb_create(struct hlist_head *head,
 354                                               struct net_bridge_port *source,
 355                                               const unsigned char *addr)
 356{
 357        struct net_bridge_fdb_entry *fdb;
 358
 359        fdb = kmem_cache_alloc(br_fdb_cache, GFP_ATOMIC);
 360        if (fdb) {
 361                memcpy(fdb->addr.addr, addr, ETH_ALEN);
 362                fdb->dst = source;
 363                fdb->is_local = 0;
 364                fdb->is_static = 0;
 365                fdb->updated = fdb->used = jiffies;
 366                hlist_add_head_rcu(&fdb->hlist, head);
 367        }
 368        return fdb;
 369}
 370
 371static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
 372                  const unsigned char *addr)
 373{
 374        struct hlist_head *head = &br->hash[br_mac_hash(addr)];
 375        struct net_bridge_fdb_entry *fdb;
 376
 377        if (!is_valid_ether_addr(addr))
 378                return -EINVAL;
 379
 380        fdb = fdb_find(head, addr);
 381        if (fdb) {
 382                /* it is okay to have multiple ports with same
 383                 * address, just use the first one.
 384                 */
 385                if (fdb->is_local)
 386                        return 0;
 387                br_warn(br, "adding interface %s with same address "
 388                       "as a received packet\n",
 389                       source->dev->name);
 390                fdb_delete(br, fdb);
 391        }
 392
 393        fdb = fdb_create(head, source, addr);
 394        if (!fdb)
 395                return -ENOMEM;
 396
 397        fdb->is_local = fdb->is_static = 1;
 398        fdb_notify(br, fdb, RTM_NEWNEIGH);
 399        return 0;
 400}
 401
 402/* Add entry for local address of interface */
 403int br_fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
 404                  const unsigned char *addr)
 405{
 406        int ret;
 407
 408        spin_lock_bh(&br->hash_lock);
 409        ret = fdb_insert(br, source, addr);
 410        spin_unlock_bh(&br->hash_lock);
 411        return ret;
 412}
 413
 414void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
 415                   const unsigned char *addr)
 416{
 417        struct hlist_head *head = &br->hash[br_mac_hash(addr)];
 418        struct net_bridge_fdb_entry *fdb;
 419
 420        /* some users want to always flood. */
 421        if (hold_time(br) == 0)
 422                return;
 423
 424        /* ignore packets unless we are using this port */
 425        if (!(source->state == BR_STATE_LEARNING ||
 426              source->state == BR_STATE_FORWARDING))
 427                return;
 428
 429        fdb = fdb_find_rcu(head, addr);
 430        if (likely(fdb)) {
 431                /* attempt to update an entry for a local interface */
 432                if (unlikely(fdb->is_local)) {
 433                        if (net_ratelimit())
 434                                br_warn(br, "received packet on %s with "
 435                                        "own address as source address\n",
 436                                        source->dev->name);
 437                } else {
 438                        /* fastpath: update of existing entry */
 439                        fdb->dst = source;
 440                        fdb->updated = jiffies;
 441                }
 442        } else {
 443                spin_lock(&br->hash_lock);
 444                if (likely(!fdb_find(head, addr))) {
 445                        fdb = fdb_create(head, source, addr);
 446                        if (fdb)
 447                                fdb_notify(br, fdb, RTM_NEWNEIGH);
 448                }
 449                /* else  we lose race and someone else inserts
 450                 * it first, don't bother updating
 451                 */
 452                spin_unlock(&br->hash_lock);
 453        }
 454}
 455
 456static int fdb_to_nud(const struct net_bridge_fdb_entry *fdb)
 457{
 458        if (fdb->is_local)
 459                return NUD_PERMANENT;
 460        else if (fdb->is_static)
 461                return NUD_NOARP;
 462        else if (has_expired(fdb->dst->br, fdb))
 463                return NUD_STALE;
 464        else
 465                return NUD_REACHABLE;
 466}
 467
 468static int fdb_fill_info(struct sk_buff *skb, const struct net_bridge *br,
 469                         const struct net_bridge_fdb_entry *fdb,
 470                         u32 pid, u32 seq, int type, unsigned int flags)
 471{
 472        unsigned long now = jiffies;
 473        struct nda_cacheinfo ci;
 474        struct nlmsghdr *nlh;
 475        struct ndmsg *ndm;
 476
 477        nlh = nlmsg_put(skb, pid, seq, type, sizeof(*ndm), flags);
 478        if (nlh == NULL)
 479                return -EMSGSIZE;
 480
 481        ndm = nlmsg_data(nlh);
 482        ndm->ndm_family  = AF_BRIDGE;
 483        ndm->ndm_pad1    = 0;
 484        ndm->ndm_pad2    = 0;
 485        ndm->ndm_flags   = 0;
 486        ndm->ndm_type    = 0;
 487        ndm->ndm_ifindex = fdb->dst ? fdb->dst->dev->ifindex : br->dev->ifindex;
 488        ndm->ndm_state   = fdb_to_nud(fdb);
 489
 490        if (nla_put(skb, NDA_LLADDR, ETH_ALEN, &fdb->addr))
 491                goto nla_put_failure;
 492        ci.ndm_used      = jiffies_to_clock_t(now - fdb->used);
 493        ci.ndm_confirmed = 0;
 494        ci.ndm_updated   = jiffies_to_clock_t(now - fdb->updated);
 495        ci.ndm_refcnt    = 0;
 496        if (nla_put(skb, NDA_CACHEINFO, sizeof(ci), &ci))
 497                goto nla_put_failure;
 498        return nlmsg_end(skb, nlh);
 499
 500nla_put_failure:
 501        nlmsg_cancel(skb, nlh);
 502        return -EMSGSIZE;
 503}
 504
 505static inline size_t fdb_nlmsg_size(void)
 506{
 507        return NLMSG_ALIGN(sizeof(struct ndmsg))
 508                + nla_total_size(ETH_ALEN) /* NDA_LLADDR */
 509                + nla_total_size(sizeof(struct nda_cacheinfo));
 510}
 511
 512static void fdb_notify(struct net_bridge *br,
 513                       const struct net_bridge_fdb_entry *fdb, int type)
 514{
 515        struct net *net = dev_net(br->dev);
 516        struct sk_buff *skb;
 517        int err = -ENOBUFS;
 518
 519        skb = nlmsg_new(fdb_nlmsg_size(), GFP_ATOMIC);
 520        if (skb == NULL)
 521                goto errout;
 522
 523        err = fdb_fill_info(skb, br, fdb, 0, 0, type, 0);
 524        if (err < 0) {
 525                /* -EMSGSIZE implies BUG in fdb_nlmsg_size() */
 526                WARN_ON(err == -EMSGSIZE);
 527                kfree_skb(skb);
 528                goto errout;
 529        }
 530        rtnl_notify(skb, net, 0, RTNLGRP_NEIGH, NULL, GFP_ATOMIC);
 531        return;
 532errout:
 533        if (err < 0)
 534                rtnl_set_sk_err(net, RTNLGRP_NEIGH, err);
 535}
 536
 537/* Dump information about entries, in response to GETNEIGH */
 538int br_fdb_dump(struct sk_buff *skb,
 539                struct netlink_callback *cb,
 540                struct net_device *dev,
 541                int idx)
 542{
 543        struct net_bridge *br = netdev_priv(dev);
 544        int i;
 545
 546        if (!(dev->priv_flags & IFF_EBRIDGE))
 547                goto out;
 548
 549        for (i = 0; i < BR_HASH_SIZE; i++) {
 550                struct hlist_node *h;
 551                struct net_bridge_fdb_entry *f;
 552
 553                hlist_for_each_entry_rcu(f, h, &br->hash[i], hlist) {
 554                        if (idx < cb->args[0])
 555                                goto skip;
 556
 557                        if (fdb_fill_info(skb, br, f,
 558                                          NETLINK_CB(cb->skb).pid,
 559                                          cb->nlh->nlmsg_seq,
 560                                          RTM_NEWNEIGH,
 561                                          NLM_F_MULTI) < 0)
 562                                break;
 563skip:
 564                        ++idx;
 565                }
 566        }
 567
 568out:
 569        return idx;
 570}
 571
 572/* Update (create or replace) forwarding database entry */
 573static int fdb_add_entry(struct net_bridge_port *source, const __u8 *addr,
 574                         __u16 state, __u16 flags)
 575{
 576        struct net_bridge *br = source->br;
 577        struct hlist_head *head = &br->hash[br_mac_hash(addr)];
 578        struct net_bridge_fdb_entry *fdb;
 579
 580        fdb = fdb_find(head, addr);
 581        if (fdb == NULL) {
 582                if (!(flags & NLM_F_CREATE))
 583                        return -ENOENT;
 584
 585                fdb = fdb_create(head, source, addr);
 586                if (!fdb)
 587                        return -ENOMEM;
 588                fdb_notify(br, fdb, RTM_NEWNEIGH);
 589        } else {
 590                if (flags & NLM_F_EXCL)
 591                        return -EEXIST;
 592        }
 593
 594        if (fdb_to_nud(fdb) != state) {
 595                if (state & NUD_PERMANENT)
 596                        fdb->is_local = fdb->is_static = 1;
 597                else if (state & NUD_NOARP) {
 598                        fdb->is_local = 0;
 599                        fdb->is_static = 1;
 600                } else
 601                        fdb->is_local = fdb->is_static = 0;
 602
 603                fdb->updated = fdb->used = jiffies;
 604                fdb_notify(br, fdb, RTM_NEWNEIGH);
 605        }
 606
 607        return 0;
 608}
 609
 610/* Add new permanent fdb entry with RTM_NEWNEIGH */
 611int br_fdb_add(struct ndmsg *ndm, struct net_device *dev,
 612               unsigned char *addr, u16 nlh_flags)
 613{
 614        struct net_bridge_port *p;
 615        int err = 0;
 616
 617        if (!(ndm->ndm_state & (NUD_PERMANENT|NUD_NOARP|NUD_REACHABLE))) {
 618                pr_info("bridge: RTM_NEWNEIGH with invalid state %#x\n", ndm->ndm_state);
 619                return -EINVAL;
 620        }
 621
 622        p = br_port_get_rtnl(dev);
 623        if (p == NULL) {
 624                pr_info("bridge: RTM_NEWNEIGH %s not a bridge port\n",
 625                        dev->name);
 626                return -EINVAL;
 627        }
 628
 629        if (ndm->ndm_flags & NTF_USE) {
 630                rcu_read_lock();
 631                br_fdb_update(p->br, p, addr);
 632                rcu_read_unlock();
 633        } else {
 634                spin_lock_bh(&p->br->hash_lock);
 635                err = fdb_add_entry(p, addr, ndm->ndm_state, nlh_flags);
 636                spin_unlock_bh(&p->br->hash_lock);
 637        }
 638
 639        return err;
 640}
 641
 642static int fdb_delete_by_addr(struct net_bridge_port *p, u8 *addr)
 643{
 644        struct net_bridge *br = p->br;
 645        struct hlist_head *head = &br->hash[br_mac_hash(addr)];
 646        struct net_bridge_fdb_entry *fdb;
 647
 648        fdb = fdb_find(head, addr);
 649        if (!fdb)
 650                return -ENOENT;
 651
 652        fdb_delete(p->br, fdb);
 653        return 0;
 654}
 655
 656/* Remove neighbor entry with RTM_DELNEIGH */
 657int br_fdb_delete(struct ndmsg *ndm, struct net_device *dev,
 658                  unsigned char *addr)
 659{
 660        struct net_bridge_port *p;
 661        int err;
 662
 663        p = br_port_get_rtnl(dev);
 664        if (p == NULL) {
 665                pr_info("bridge: RTM_DELNEIGH %s not a bridge port\n",
 666                        dev->name);
 667                return -EINVAL;
 668        }
 669
 670        spin_lock_bh(&p->br->hash_lock);
 671        err = fdb_delete_by_addr(p, addr);
 672        spin_unlock_bh(&p->br->hash_lock);
 673
 674        return err;
 675}
 676
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