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