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         sk_add_bind_node(child, &tb->owners);
 137         inet_csk(child)->icsk_bind_hash = tb;
 138         spin_unlock(&head->lock);
 139
 140         return 0;
 141 }
 142 EXPORT_SYMBOL_GPL(__inet_inherit_port);
 143
 144 static 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
 177 struct 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();
 189 begin:
 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 }
 218 EXPORT_SYMBOL_GPL(__inet_lookup_listener);
 219
 220 struct 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();
 238 begin:
 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
 260 begintw:
 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;
 285 out:
 286         rcu_read_unlock();
 287         return sk;
 288 }
 289 EXPORT_SYMBOL_GPL(__inet_lookup_established);
 290
 291 /* called with local bh disabled */
 292 static 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
 336 unique:
 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
 363 not_unique:
 364         spin_unlock(lock);
 365         return -EADDRNOTAVAIL;
 366 }
 367
 368 static 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
 376 int __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 }
 401 EXPORT_SYMBOL_GPL(__inet_hash_nolisten);
 402
 403 static 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
 422 void 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 }
 430 EXPORT_SYMBOL_GPL(inet_hash);
 431
 432 void 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 }
 452 EXPORT_SYMBOL_GPL(inet_unhash);
 453
 454 int __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
 520 ok:
 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);
 556 out:
 557                 local_bh_enable();
 558                 return ret;
 559         }
 560 }
 561
 562 /*
 563  * Bind a port for a connect operation and hash it.
 564  */
 565 int 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 }
 571 EXPORT_SYMBOL_GPL(inet_hash_connect);
 572
 573 void 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 }
 584 EXPORT_SYMBOL_GPL(inet_hashinfo_init);