net/ipv4/inet_hashtables.c

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