linux/net/ipv4/inet_hashtables.c
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   1/*
   2 * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3 *              operating system.  INET is implemented using the BSD Socket
   4 *              interface as the means of communication with the user level.
   5 *
   6 *              Generic INET transport hashtables
   7 *
   8 * Authors:     Lotsa people, from code originally in tcp
   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/module.h>
  17#include <linux/random.h>
  18#include <linux/sched.h>
  19#include <linux/slab.h>
  20#include <linux/wait.h>
  21
  22#include <net/inet_connection_sock.h>
  23#include <net/inet_hashtables.h>
  24#include <net/secure_seq.h>
  25#include <net/ip.h>
  26
  27/*
  28 * Allocate and initialize a new local port bind bucket.
  29 * The bindhash mutex for snum's hash chain must be held here.
  30 */
  31struct inet_bind_bucket *inet_bind_bucket_create(struct kmem_cache *cachep,
  32                                                 struct net *net,
  33                                                 struct inet_bind_hashbucket *head,
  34                                                 const unsigned short snum)
  35{
  36        struct inet_bind_bucket *tb = kmem_cache_alloc(cachep, GFP_ATOMIC);
  37
  38        if (tb != NULL) {
  39                write_pnet(&tb->ib_net, hold_net(net));
  40                tb->port      = snum;
  41                tb->fastreuse = 0;
  42                tb->num_owners = 0;
  43                INIT_HLIST_HEAD(&tb->owners);
  44                hlist_add_head(&tb->node, &head->chain);
  45        }
  46        return tb;
  47}
  48
  49/*
  50 * Caller must hold hashbucket lock for this tb with local BH disabled
  51 */
  52void inet_bind_bucket_destroy(struct kmem_cache *cachep, struct inet_bind_bucket *tb)
  53{
  54        if (hlist_empty(&tb->owners)) {
  55                __hlist_del(&tb->node);
  56                release_net(ib_net(tb));
  57                kmem_cache_free(cachep, tb);
  58        }
  59}
  60
  61void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,
  62                    const unsigned short snum)
  63{
  64        struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
  65
  66        atomic_inc(&hashinfo->bsockets);
  67
  68        inet_sk(sk)->inet_num = snum;
  69        sk_add_bind_node(sk, &tb->owners);
  70        tb->num_owners++;
  71        inet_csk(sk)->icsk_bind_hash = tb;
  72}
  73
  74/*
  75 * Get rid of any references to a local port held by the given sock.
  76 */
  77static void __inet_put_port(struct sock *sk)
  78{
  79        struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
  80        const int bhash = inet_bhashfn(sock_net(sk), inet_sk(sk)->inet_num,
  81                        hashinfo->bhash_size);
  82        struct inet_bind_hashbucket *head = &hashinfo->bhash[bhash];
  83        struct inet_bind_bucket *tb;
  84
  85        atomic_dec(&hashinfo->bsockets);
  86
  87        spin_lock(&head->lock);
  88        tb = inet_csk(sk)->icsk_bind_hash;
  89        __sk_del_bind_node(sk);
  90        tb->num_owners--;
  91        inet_csk(sk)->icsk_bind_hash = NULL;
  92        inet_sk(sk)->inet_num = 0;
  93        inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb);
  94        spin_unlock(&head->lock);
  95}
  96
  97void inet_put_port(struct sock *sk)
  98{
  99        local_bh_disable();
 100        __inet_put_port(sk);
 101        local_bh_enable();
 102}
 103EXPORT_SYMBOL(inet_put_port);
 104
 105int __inet_inherit_port(struct sock *sk, struct sock *child)
 106{
 107        struct inet_hashinfo *table = sk->sk_prot->h.hashinfo;
 108        unsigned short port = inet_sk(child)->inet_num;
 109        const int bhash = inet_bhashfn(sock_net(sk), port,
 110                        table->bhash_size);
 111        struct inet_bind_hashbucket *head = &table->bhash[bhash];
 112        struct inet_bind_bucket *tb;
 113
 114        spin_lock(&head->lock);
 115        tb = inet_csk(sk)->icsk_bind_hash;
 116        if (tb->port != port) {
 117                /* NOTE: using tproxy and redirecting skbs to a proxy
 118                 * on a different listener port breaks the assumption
 119                 * that the listener socket's icsk_bind_hash is the same
 120                 * as that of the child socket. We have to look up or
 121                 * create a new bind bucket for the child here. */
 122                struct hlist_node *node;
 123                inet_bind_bucket_for_each(tb, node, &head->chain) {
 124                        if (net_eq(ib_net(tb), sock_net(sk)) &&
 125                            tb->port == port)
 126                                break;
 127                }
 128                if (!node) {
 129                        tb = inet_bind_bucket_create(table->bind_bucket_cachep,
 130                                                     sock_net(sk), head, port);
 131                        if (!tb) {
 132                                spin_unlock(&head->lock);
 133                                return -ENOMEM;
 134                        }
 135                }
 136        }
 137        inet_bind_hash(child, tb, port);
 138        spin_unlock(&head->lock);
 139
 140        return 0;
 141}
 142EXPORT_SYMBOL_GPL(__inet_inherit_port);
 143
 144static inline int compute_score(struct sock *sk, struct net *net,
 145                                const unsigned short hnum, const __be32 daddr,
 146                                const int dif)
 147{
 148        int score = -1;
 149        struct inet_sock *inet = inet_sk(sk);
 150
 151        if (net_eq(sock_net(sk), net) && inet->inet_num == hnum &&
 152                        !ipv6_only_sock(sk)) {
 153                __be32 rcv_saddr = inet->inet_rcv_saddr;
 154                score = sk->sk_family == PF_INET ? 1 : 0;
 155                if (rcv_saddr) {
 156                        if (rcv_saddr != daddr)
 157                                return -1;
 158                        score += 2;
 159                }
 160                if (sk->sk_bound_dev_if) {
 161                        if (sk->sk_bound_dev_if != dif)
 162                                return -1;
 163                        score += 2;
 164                }
 165        }
 166        return score;
 167}
 168
 169/*
 170 * Don't inline this cruft. Here are some nice properties to exploit here. The
 171 * BSD API does not allow a listening sock to specify the remote port nor the
 172 * remote address for the connection. So always assume those are both
 173 * wildcarded during the search since they can never be otherwise.
 174 */
 175
 176
 177struct sock *__inet_lookup_listener(struct net *net,
 178                                    struct inet_hashinfo *hashinfo,
 179                                    const __be32 daddr, const unsigned short hnum,
 180                                    const int dif)
 181{
 182        struct sock *sk, *result;
 183        struct hlist_nulls_node *node;
 184        unsigned int hash = inet_lhashfn(net, hnum);
 185        struct inet_listen_hashbucket *ilb = &hashinfo->listening_hash[hash];
 186        int score, hiscore;
 187
 188        rcu_read_lock();
 189begin:
 190        result = NULL;
 191        hiscore = -1;
 192        sk_nulls_for_each_rcu(sk, node, &ilb->head) {
 193                score = compute_score(sk, net, hnum, daddr, dif);
 194                if (score > hiscore) {
 195                        result = sk;
 196                        hiscore = score;
 197                }
 198        }
 199        /*
 200         * if the nulls value we got at the end of this lookup is
 201         * not the expected one, we must restart lookup.
 202         * We probably met an item that was moved to another chain.
 203         */
 204        if (get_nulls_value(node) != hash + LISTENING_NULLS_BASE)
 205                goto begin;
 206        if (result) {
 207                if (unlikely(!atomic_inc_not_zero(&result->sk_refcnt)))
 208                        result = NULL;
 209                else if (unlikely(compute_score(result, net, hnum, daddr,
 210                                  dif) < hiscore)) {
 211                        sock_put(result);
 212                        goto begin;
 213                }
 214        }
 215        rcu_read_unlock();
 216        return result;
 217}
 218EXPORT_SYMBOL_GPL(__inet_lookup_listener);
 219
 220struct sock *__inet_lookup_established(struct net *net,
 221                                  struct inet_hashinfo *hashinfo,
 222                                  const __be32 saddr, const __be16 sport,
 223                                  const __be32 daddr, const u16 hnum,
 224                                  const int dif)
 225{
 226        INET_ADDR_COOKIE(acookie, saddr, daddr)
 227        const __portpair ports = INET_COMBINED_PORTS(sport, hnum);
 228        struct sock *sk;
 229        const struct hlist_nulls_node *node;
 230        /* Optimize here for direct hit, only listening connections can
 231         * have wildcards anyways.
 232         */
 233        unsigned int hash = inet_ehashfn(net, daddr, hnum, saddr, sport);
 234        unsigned int slot = hash & hashinfo->ehash_mask;
 235        struct inet_ehash_bucket *head = &hashinfo->ehash[slot];
 236
 237        rcu_read_lock();
 238begin:
 239        sk_nulls_for_each_rcu(sk, node, &head->chain) {
 240                if (INET_MATCH(sk, net, hash, acookie,
 241                                        saddr, daddr, ports, dif)) {
 242                        if (unlikely(!atomic_inc_not_zero(&sk->sk_refcnt)))
 243                                goto begintw;
 244                        if (unlikely(!INET_MATCH(sk, net, hash, acookie,
 245                                saddr, daddr, ports, dif))) {
 246                                sock_put(sk);
 247                                goto begin;
 248                        }
 249                        goto out;
 250                }
 251        }
 252        /*
 253         * if the nulls value we got at the end of this lookup is
 254         * not the expected one, we must restart lookup.
 255         * We probably met an item that was moved to another chain.
 256         */
 257        if (get_nulls_value(node) != slot)
 258                goto begin;
 259
 260begintw:
 261        /* Must check for a TIME_WAIT'er before going to listener hash. */
 262        sk_nulls_for_each_rcu(sk, node, &head->twchain) {
 263                if (INET_TW_MATCH(sk, net, hash, acookie,
 264                                        saddr, daddr, ports, dif)) {
 265                        if (unlikely(!atomic_inc_not_zero(&sk->sk_refcnt))) {
 266                                sk = NULL;
 267                                goto out;
 268                        }
 269                        if (unlikely(!INET_TW_MATCH(sk, net, hash, acookie,
 270                                 saddr, daddr, ports, dif))) {
 271                                sock_put(sk);
 272                                goto begintw;
 273                        }
 274                        goto out;
 275                }
 276        }
 277        /*
 278         * if the nulls value we got at the end of this lookup is
 279         * not the expected one, we must restart lookup.
 280         * We probably met an item that was moved to another chain.
 281         */
 282        if (get_nulls_value(node) != slot)
 283                goto begintw;
 284        sk = NULL;
 285out:
 286        rcu_read_unlock();
 287        return sk;
 288}
 289EXPORT_SYMBOL_GPL(__inet_lookup_established);
 290
 291/* called with local bh disabled */
 292static int __inet_check_established(struct inet_timewait_death_row *death_row,
 293                                    struct sock *sk, __u16 lport,
 294                                    struct inet_timewait_sock **twp)
 295{
 296        struct inet_hashinfo *hinfo = death_row->hashinfo;
 297        struct inet_sock *inet = inet_sk(sk);
 298        __be32 daddr = inet->inet_rcv_saddr;
 299        __be32 saddr = inet->inet_daddr;
 300        int dif = sk->sk_bound_dev_if;
 301        INET_ADDR_COOKIE(acookie, saddr, daddr)
 302        const __portpair ports = INET_COMBINED_PORTS(inet->inet_dport, lport);
 303        struct net *net = sock_net(sk);
 304        unsigned int hash = inet_ehashfn(net, daddr, lport,
 305                                         saddr, inet->inet_dport);
 306        struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);
 307        spinlock_t *lock = inet_ehash_lockp(hinfo, hash);
 308        struct sock *sk2;
 309        const struct hlist_nulls_node *node;
 310        struct inet_timewait_sock *tw;
 311        int twrefcnt = 0;
 312
 313        spin_lock(lock);
 314
 315        /* Check TIME-WAIT sockets first. */
 316        sk_nulls_for_each(sk2, node, &head->twchain) {
 317                tw = inet_twsk(sk2);
 318
 319                if (INET_TW_MATCH(sk2, net, hash, acookie,
 320                                        saddr, daddr, ports, dif)) {
 321                        if (twsk_unique(sk, sk2, twp))
 322                                goto unique;
 323                        else
 324                                goto not_unique;
 325                }
 326        }
 327        tw = NULL;
 328
 329        /* And established part... */
 330        sk_nulls_for_each(sk2, node, &head->chain) {
 331                if (INET_MATCH(sk2, net, hash, acookie,
 332                                        saddr, daddr, ports, dif))
 333                        goto not_unique;
 334        }
 335
 336unique:
 337        /* Must record num and sport now. Otherwise we will see
 338         * in hash table socket with a funny identity. */
 339        inet->inet_num = lport;
 340        inet->inet_sport = htons(lport);
 341        sk->sk_hash = hash;
 342        WARN_ON(!sk_unhashed(sk));
 343        __sk_nulls_add_node_rcu(sk, &head->chain);
 344        if (tw) {
 345                twrefcnt = inet_twsk_unhash(tw);
 346                NET_INC_STATS_BH(net, LINUX_MIB_TIMEWAITRECYCLED);
 347        }
 348        spin_unlock(lock);
 349        if (twrefcnt)
 350                inet_twsk_put(tw);
 351        sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
 352
 353        if (twp) {
 354                *twp = tw;
 355        } else if (tw) {
 356                /* Silly. Should hash-dance instead... */
 357                inet_twsk_deschedule(tw, death_row);
 358
 359                inet_twsk_put(tw);
 360        }
 361        return 0;
 362
 363not_unique:
 364        spin_unlock(lock);
 365        return -EADDRNOTAVAIL;
 366}
 367
 368static inline u32 inet_sk_port_offset(const struct sock *sk)
 369{
 370        const struct inet_sock *inet = inet_sk(sk);
 371        return secure_ipv4_port_ephemeral(inet->inet_rcv_saddr,
 372                                          inet->inet_daddr,
 373                                          inet->inet_dport);
 374}
 375
 376int __inet_hash_nolisten(struct sock *sk, struct inet_timewait_sock *tw)
 377{
 378        struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
 379        struct hlist_nulls_head *list;
 380        spinlock_t *lock;
 381        struct inet_ehash_bucket *head;
 382        int twrefcnt = 0;
 383
 384        WARN_ON(!sk_unhashed(sk));
 385
 386        sk->sk_hash = inet_sk_ehashfn(sk);
 387        head = inet_ehash_bucket(hashinfo, sk->sk_hash);
 388        list = &head->chain;
 389        lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
 390
 391        spin_lock(lock);
 392        __sk_nulls_add_node_rcu(sk, list);
 393        if (tw) {
 394                WARN_ON(sk->sk_hash != tw->tw_hash);
 395                twrefcnt = inet_twsk_unhash(tw);
 396        }
 397        spin_unlock(lock);
 398        sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
 399        return twrefcnt;
 400}
 401EXPORT_SYMBOL_GPL(__inet_hash_nolisten);
 402
 403static void __inet_hash(struct sock *sk)
 404{
 405        struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
 406        struct inet_listen_hashbucket *ilb;
 407
 408        if (sk->sk_state != TCP_LISTEN) {
 409                __inet_hash_nolisten(sk, NULL);
 410                return;
 411        }
 412
 413        WARN_ON(!sk_unhashed(sk));
 414        ilb = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)];
 415
 416        spin_lock(&ilb->lock);
 417        __sk_nulls_add_node_rcu(sk, &ilb->head);
 418        sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
 419        spin_unlock(&ilb->lock);
 420}
 421
 422void inet_hash(struct sock *sk)
 423{
 424        if (sk->sk_state != TCP_CLOSE) {
 425                local_bh_disable();
 426                __inet_hash(sk);
 427                local_bh_enable();
 428        }
 429}
 430EXPORT_SYMBOL_GPL(inet_hash);
 431
 432void inet_unhash(struct sock *sk)
 433{
 434        struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
 435        spinlock_t *lock;
 436        int done;
 437
 438        if (sk_unhashed(sk))
 439                return;
 440
 441        if (sk->sk_state == TCP_LISTEN)
 442                lock = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)].lock;
 443        else
 444                lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
 445
 446        spin_lock_bh(lock);
 447        done =__sk_nulls_del_node_init_rcu(sk);
 448        if (done)
 449                sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
 450        spin_unlock_bh(lock);
 451}
 452EXPORT_SYMBOL_GPL(inet_unhash);
 453
 454int __inet_hash_connect(struct inet_timewait_death_row *death_row,
 455                struct sock *sk, u32 port_offset,
 456                int (*check_established)(struct inet_timewait_death_row *,
 457                        struct sock *, __u16, struct inet_timewait_sock **),
 458                int (*hash)(struct sock *sk, struct inet_timewait_sock *twp))
 459{
 460        struct inet_hashinfo *hinfo = death_row->hashinfo;
 461        const unsigned short snum = inet_sk(sk)->inet_num;
 462        struct inet_bind_hashbucket *head;
 463        struct inet_bind_bucket *tb;
 464        int ret;
 465        struct net *net = sock_net(sk);
 466        int twrefcnt = 1;
 467
 468        if (!snum) {
 469                int i, remaining, low, high, port;
 470                static u32 hint;
 471                u32 offset = hint + port_offset;
 472                struct hlist_node *node;
 473                struct inet_timewait_sock *tw = NULL;
 474
 475                inet_get_local_port_range(&low, &high);
 476                remaining = (high - low) + 1;
 477
 478                local_bh_disable();
 479                for (i = 1; i <= remaining; i++) {
 480                        port = low + (i + offset) % remaining;
 481                        if (inet_is_reserved_local_port(port))
 482                                continue;
 483                        head = &hinfo->bhash[inet_bhashfn(net, port,
 484                                        hinfo->bhash_size)];
 485                        spin_lock(&head->lock);
 486
 487                        /* Does not bother with rcv_saddr checks,
 488                         * because the established check is already
 489                         * unique enough.
 490                         */
 491                        inet_bind_bucket_for_each(tb, node, &head->chain) {
 492                                if (net_eq(ib_net(tb), net) &&
 493                                    tb->port == port) {
 494                                        if (tb->fastreuse >= 0)
 495                                                goto next_port;
 496                                        WARN_ON(hlist_empty(&tb->owners));
 497                                        if (!check_established(death_row, sk,
 498                                                                port, &tw))
 499                                                goto ok;
 500                                        goto next_port;
 501                                }
 502                        }
 503
 504                        tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep,
 505                                        net, head, port);
 506                        if (!tb) {
 507                                spin_unlock(&head->lock);
 508                                break;
 509                        }
 510                        tb->fastreuse = -1;
 511                        goto ok;
 512
 513                next_port:
 514                        spin_unlock(&head->lock);
 515                }
 516                local_bh_enable();
 517
 518                return -EADDRNOTAVAIL;
 519
 520ok:
 521                hint += i;
 522
 523                /* Head lock still held and bh's disabled */
 524                inet_bind_hash(sk, tb, port);
 525                if (sk_unhashed(sk)) {
 526                        inet_sk(sk)->inet_sport = htons(port);
 527                        twrefcnt += hash(sk, tw);
 528                }
 529                if (tw)
 530                        twrefcnt += inet_twsk_bind_unhash(tw, hinfo);
 531                spin_unlock(&head->lock);
 532
 533                if (tw) {
 534                        inet_twsk_deschedule(tw, death_row);
 535                        while (twrefcnt) {
 536                                twrefcnt--;
 537                                inet_twsk_put(tw);
 538                        }
 539                }
 540
 541                ret = 0;
 542                goto out;
 543        }
 544
 545        head = &hinfo->bhash[inet_bhashfn(net, snum, hinfo->bhash_size)];
 546        tb  = inet_csk(sk)->icsk_bind_hash;
 547        spin_lock_bh(&head->lock);
 548        if (sk_head(&tb->owners) == sk && !sk->sk_bind_node.next) {
 549                hash(sk, NULL);
 550                spin_unlock_bh(&head->lock);
 551                return 0;
 552        } else {
 553                spin_unlock(&head->lock);
 554                /* No definite answer... Walk to established hash table */
 555                ret = check_established(death_row, sk, snum, NULL);
 556out:
 557                local_bh_enable();
 558                return ret;
 559        }
 560}
 561
 562/*
 563 * Bind a port for a connect operation and hash it.
 564 */
 565int inet_hash_connect(struct inet_timewait_death_row *death_row,
 566                      struct sock *sk)
 567{
 568        return __inet_hash_connect(death_row, sk, inet_sk_port_offset(sk),
 569                        __inet_check_established, __inet_hash_nolisten);
 570}
 571EXPORT_SYMBOL_GPL(inet_hash_connect);
 572
 573void inet_hashinfo_init(struct inet_hashinfo *h)
 574{
 575        int i;
 576
 577        atomic_set(&h->bsockets, 0);
 578        for (i = 0; i < INET_LHTABLE_SIZE; i++) {
 579                spin_lock_init(&h->listening_hash[i].lock);
 580                INIT_HLIST_NULLS_HEAD(&h->listening_hash[i].head,
 581                                      i + LISTENING_NULLS_BASE);
 582                }
 583}
 584EXPORT_SYMBOL_GPL(inet_hashinfo_init);
 585
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