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                 tb->ib_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                 kmem_cache_free(cachep, tb);
  55         }
  56 }
  57
  58 void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,
  59                     const unsigned short snum)
  60 {
  61         inet_sk(sk)->num = snum;
  62         sk_add_bind_node(sk, &tb->owners);
  63         inet_csk(sk)->icsk_bind_hash = tb;
  64 }
  65
  66 /*
  67  * Get rid of any references to a local port held by the given sock.
  68  */
  69 static void __inet_put_port(struct sock *sk)
  70 {
  71         struct inet_hashinfo *hashinfo = sk->sk_prot->hashinfo;
  72         const int bhash = inet_bhashfn(inet_sk(sk)->num, hashinfo->bhash_size);
  73         struct inet_bind_hashbucket *head = &hashinfo->bhash[bhash];
  74         struct inet_bind_bucket *tb;
  75
  76         spin_lock(&head->lock);
  77         tb = inet_csk(sk)->icsk_bind_hash;
  78         __sk_del_bind_node(sk);
  79         inet_csk(sk)->icsk_bind_hash = NULL;
  80         inet_sk(sk)->num = 0;
  81         inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb);
  82         spin_unlock(&head->lock);
  83 }
  84
  85 void inet_put_port(struct sock *sk)
  86 {
  87         local_bh_disable();
  88         __inet_put_port(sk);
  89         local_bh_enable();
  90 }
  91
  92 EXPORT_SYMBOL(inet_put_port);
  93
  94 /*
  95  * This lock without WQ_FLAG_EXCLUSIVE is good on UP and it can be very bad on SMP.
  96  * Look, when several writers sleep and reader wakes them up, all but one
  97  * immediately hit write lock and grab all the cpus. Exclusive sleep solves
  98  * this, _but_ remember, it adds useless work on UP machines (wake up each
  99  * exclusive lock release). It should be ifdefed really.
 100  */
 101 void inet_listen_wlock(struct inet_hashinfo *hashinfo)
 102         __acquires(hashinfo->lhash_lock)
 103 {
 104         write_lock(&hashinfo->lhash_lock);
 105
 106         if (atomic_read(&hashinfo->lhash_users)) {
 107                 DEFINE_WAIT(wait);
 108
 109                 for (;;) {
 110                         prepare_to_wait_exclusive(&hashinfo->lhash_wait,
 111                                                   &wait, TASK_UNINTERRUPTIBLE);
 112                         if (!atomic_read(&hashinfo->lhash_users))
 113                                 break;
 114                         write_unlock_bh(&hashinfo->lhash_lock);
 115                         schedule();
 116                         write_lock_bh(&hashinfo->lhash_lock);
 117                 }
 118
 119                 finish_wait(&hashinfo->lhash_wait, &wait);
 120         }
 121 }
 122
 123 EXPORT_SYMBOL(inet_listen_wlock);
 124
 125 /*
 126  * Don't inline this cruft. Here are some nice properties to exploit here. The
 127  * BSD API does not allow a listening sock to specify the remote port nor the
 128  * remote address for the connection. So always assume those are both
 129  * wildcarded during the search since they can never be otherwise.
 130  */
 131 static struct sock *inet_lookup_listener_slow(struct net *net,
 132                                               const struct hlist_head *head,
 133                                               const __be32 daddr,
 134                                               const unsigned short hnum,
 135                                               const int dif)
 136 {
 137         struct sock *result = NULL, *sk;
 138         const struct hlist_node *node;
 139         int hiscore = -1;
 140
 141         sk_for_each(sk, node, head) {
 142                 const struct inet_sock *inet = inet_sk(sk);
 143
 144                 if (sk->sk_net == net && inet->num == hnum &&
 145                                 !ipv6_only_sock(sk)) {
 146                         const __be32 rcv_saddr = inet->rcv_saddr;
 147                         int score = sk->sk_family == PF_INET ? 1 : 0;
 148
 149                         if (rcv_saddr) {
 150                                 if (rcv_saddr != daddr)
 151                                         continue;
 152                                 score += 2;
 153                         }
 154                         if (sk->sk_bound_dev_if) {
 155                                 if (sk->sk_bound_dev_if != dif)
 156                                         continue;
 157                                 score += 2;
 158                         }
 159                         if (score == 5)
 160                                 return sk;
 161                         if (score > hiscore) {
 162                                 hiscore = score;
 163                                 result  = sk;
 164                         }
 165                 }
 166         }
 167         return result;
 168 }
 169
 170 /* Optimize the common listener case. */
 171 struct sock *__inet_lookup_listener(struct net *net,
 172                                     struct inet_hashinfo *hashinfo,
 173                                     const __be32 daddr, const unsigned short hnum,
 174                                     const int dif)
 175 {
 176         struct sock *sk = NULL;
 177         const struct hlist_head *head;
 178
 179         read_lock(&hashinfo->lhash_lock);
 180         head = &hashinfo->listening_hash[inet_lhashfn(hnum)];
 181         if (!hlist_empty(head)) {
 182                 const struct inet_sock *inet = inet_sk((sk = __sk_head(head)));
 183
 184                 if (inet->num == hnum && !sk->sk_node.next &&
 185                     (!inet->rcv_saddr || inet->rcv_saddr == daddr) &&
 186                     (sk->sk_family == PF_INET || !ipv6_only_sock(sk)) &&
 187                     !sk->sk_bound_dev_if && sk->sk_net == net)
 188                         goto sherry_cache;
 189                 sk = inet_lookup_listener_slow(net, head, daddr, hnum, dif);
 190         }
 191         if (sk) {
 192 sherry_cache:
 193                 sock_hold(sk);
 194         }
 195         read_unlock(&hashinfo->lhash_lock);
 196         return sk;
 197 }
 198 EXPORT_SYMBOL_GPL(__inet_lookup_listener);
 199
 200 struct sock * __inet_lookup_established(struct net *net,
 201                                   struct inet_hashinfo *hashinfo,
 202                                   const __be32 saddr, const __be16 sport,
 203                                   const __be32 daddr, const u16 hnum,
 204                                   const int dif)
 205 {
 206         INET_ADDR_COOKIE(acookie, saddr, daddr)
 207         const __portpair ports = INET_COMBINED_PORTS(sport, hnum);
 208         struct sock *sk;
 209         const struct hlist_node *node;
 210         /* Optimize here for direct hit, only listening connections can
 211          * have wildcards anyways.
 212          */
 213         unsigned int hash = inet_ehashfn(daddr, hnum, saddr, sport);
 214         struct inet_ehash_bucket *head = inet_ehash_bucket(hashinfo, hash);
 215         rwlock_t *lock = inet_ehash_lockp(hashinfo, hash);
 216
 217         prefetch(head->chain.first);
 218         read_lock(lock);
 219         sk_for_each(sk, node, &head->chain) {
 220                 if (INET_MATCH(sk, net, hash, acookie,
 221                                         saddr, daddr, ports, dif))
 222                         goto hit; /* You sunk my battleship! */
 223         }
 224
 225         /* Must check for a TIME_WAIT'er before going to listener hash. */
 226         sk_for_each(sk, node, &head->twchain) {
 227                 if (INET_TW_MATCH(sk, net, hash, acookie,
 228                                         saddr, daddr, ports, dif))
 229                         goto hit;
 230         }
 231         sk = NULL;
 232 out:
 233         read_unlock(lock);
 234         return sk;
 235 hit:
 236         sock_hold(sk);
 237         goto out;
 238 }
 239 EXPORT_SYMBOL_GPL(__inet_lookup_established);
 240
 241 /* called with local bh disabled */
 242 static int __inet_check_established(struct inet_timewait_death_row *death_row,
 243                                     struct sock *sk, __u16 lport,
 244                                     struct inet_timewait_sock **twp)
 245 {
 246         struct inet_hashinfo *hinfo = death_row->hashinfo;
 247         struct inet_sock *inet = inet_sk(sk);
 248         __be32 daddr = inet->rcv_saddr;
 249         __be32 saddr = inet->daddr;
 250         int dif = sk->sk_bound_dev_if;
 251         INET_ADDR_COOKIE(acookie, saddr, daddr)
 252         const __portpair ports = INET_COMBINED_PORTS(inet->dport, lport);
 253         unsigned int hash = inet_ehashfn(daddr, lport, saddr, inet->dport);
 254         struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);
 255         rwlock_t *lock = inet_ehash_lockp(hinfo, hash);
 256         struct sock *sk2;
 257         const struct hlist_node *node;
 258         struct inet_timewait_sock *tw;
 259         struct net *net = sk->sk_net;
 260
 261         prefetch(head->chain.first);
 262         write_lock(lock);
 263
 264         /* Check TIME-WAIT sockets first. */
 265         sk_for_each(sk2, node, &head->twchain) {
 266                 tw = inet_twsk(sk2);
 267
 268                 if (INET_TW_MATCH(sk2, net, hash, acookie,
 269                                         saddr, daddr, ports, dif)) {
 270                         if (twsk_unique(sk, sk2, twp))
 271                                 goto unique;
 272                         else
 273                                 goto not_unique;
 274                 }
 275         }
 276         tw = NULL;
 277
 278         /* And established part... */
 279         sk_for_each(sk2, node, &head->chain) {
 280                 if (INET_MATCH(sk2, net, hash, acookie,
 281                                         saddr, daddr, ports, dif))
 282                         goto not_unique;
 283         }
 284
 285 unique:
 286         /* Must record num and sport now. Otherwise we will see
 287          * in hash table socket with a funny identity. */
 288         inet->num = lport;
 289         inet->sport = htons(lport);
 290         sk->sk_hash = hash;
 291         BUG_TRAP(sk_unhashed(sk));
 292         __sk_add_node(sk, &head->chain);
 293         sock_prot_inuse_add(sk->sk_prot, 1);
 294         write_unlock(lock);
 295
 296         if (twp) {
 297                 *twp = tw;
 298                 NET_INC_STATS_BH(LINUX_MIB_TIMEWAITRECYCLED);
 299         } else if (tw) {
 300                 /* Silly. Should hash-dance instead... */
 301                 inet_twsk_deschedule(tw, death_row);
 302                 NET_INC_STATS_BH(LINUX_MIB_TIMEWAITRECYCLED);
 303
 304                 inet_twsk_put(tw);
 305         }
 306
 307         return 0;
 308
 309 not_unique:
 310         write_unlock(lock);
 311         return -EADDRNOTAVAIL;
 312 }
 313
 314 static inline u32 inet_sk_port_offset(const struct sock *sk)
 315 {
 316         const struct inet_sock *inet = inet_sk(sk);
 317         return secure_ipv4_port_ephemeral(inet->rcv_saddr, inet->daddr,
 318                                           inet->dport);
 319 }
 320
 321 void __inet_hash_nolisten(struct sock *sk)
 322 {
 323         struct inet_hashinfo *hashinfo = sk->sk_prot->hashinfo;
 324         struct hlist_head *list;
 325         rwlock_t *lock;
 326         struct inet_ehash_bucket *head;
 327
 328         BUG_TRAP(sk_unhashed(sk));
 329
 330         sk->sk_hash = inet_sk_ehashfn(sk);
 331         head = inet_ehash_bucket(hashinfo, sk->sk_hash);
 332         list = &head->chain;
 333         lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
 334
 335         write_lock(lock);
 336         __sk_add_node(sk, list);
 337         sock_prot_inuse_add(sk->sk_prot, 1);
 338         write_unlock(lock);
 339 }
 340 EXPORT_SYMBOL_GPL(__inet_hash_nolisten);
 341
 342 static void __inet_hash(struct sock *sk)
 343 {
 344         struct inet_hashinfo *hashinfo = sk->sk_prot->hashinfo;
 345         struct hlist_head *list;
 346         rwlock_t *lock;
 347
 348         if (sk->sk_state != TCP_LISTEN) {
 349                 __inet_hash_nolisten(sk);
 350                 return;
 351         }
 352
 353         BUG_TRAP(sk_unhashed(sk));
 354         list = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)];
 355         lock = &hashinfo->lhash_lock;
 356
 357         inet_listen_wlock(hashinfo);
 358         __sk_add_node(sk, list);
 359         sock_prot_inuse_add(sk->sk_prot, 1);
 360         write_unlock(lock);
 361         wake_up(&hashinfo->lhash_wait);
 362 }
 363
 364 void inet_hash(struct sock *sk)
 365 {
 366         if (sk->sk_state != TCP_CLOSE) {
 367                 local_bh_disable();
 368                 __inet_hash(sk);
 369                 local_bh_enable();
 370         }
 371 }
 372 EXPORT_SYMBOL_GPL(inet_hash);
 373
 374 void inet_unhash(struct sock *sk)
 375 {
 376         rwlock_t *lock;
 377         struct inet_hashinfo *hashinfo = sk->sk_prot->hashinfo;
 378
 379         if (sk_unhashed(sk))
 380                 goto out;
 381
 382         if (sk->sk_state == TCP_LISTEN) {
 383                 local_bh_disable();
 384                 inet_listen_wlock(hashinfo);
 385                 lock = &hashinfo->lhash_lock;
 386         } else {
 387                 lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
 388                 write_lock_bh(lock);
 389         }
 390
 391         if (__sk_del_node_init(sk))
 392                 sock_prot_inuse_add(sk->sk_prot, -1);
 393         write_unlock_bh(lock);
 394 out:
 395         if (sk->sk_state == TCP_LISTEN)
 396                 wake_up(&hashinfo->lhash_wait);
 397 }
 398 EXPORT_SYMBOL_GPL(inet_unhash);
 399
 400 int __inet_hash_connect(struct inet_timewait_death_row *death_row,
 401                 struct sock *sk, u32 port_offset,
 402                 int (*check_established)(struct inet_timewait_death_row *,
 403                         struct sock *, __u16, struct inet_timewait_sock **),
 404                 void (*hash)(struct sock *sk))
 405 {
 406         struct inet_hashinfo *hinfo = death_row->hashinfo;
 407         const unsigned short snum = inet_sk(sk)->num;
 408         struct inet_bind_hashbucket *head;
 409         struct inet_bind_bucket *tb;
 410         int ret;
 411         struct net *net = sk->sk_net;
 412
 413         if (!snum) {
 414                 int i, remaining, low, high, port;
 415                 static u32 hint;
 416                 u32 offset = hint + port_offset;
 417                 struct hlist_node *node;
 418                 struct inet_timewait_sock *tw = NULL;
 419
 420                 inet_get_local_port_range(&low, &high);
 421                 remaining = (high - low) + 1;
 422
 423                 local_bh_disable();
 424                 for (i = 1; i <= remaining; i++) {
 425                         port = low + (i + offset) % remaining;
 426                         head = &hinfo->bhash[inet_bhashfn(port, hinfo->bhash_size)];
 427                         spin_lock(&head->lock);
 428
 429                         /* Does not bother with rcv_saddr checks,
 430                          * because the established check is already
 431                          * unique enough.
 432                          */
 433                         inet_bind_bucket_for_each(tb, node, &head->chain) {
 434                                 if (tb->ib_net == net && tb->port == port) {
 435                                         BUG_TRAP(!hlist_empty(&tb->owners));
 436                                         if (tb->fastreuse >= 0)
 437                                                 goto next_port;
 438                                         if (!check_established(death_row, sk,
 439                                                                 port, &tw))
 440                                                 goto ok;
 441                                         goto next_port;
 442                                 }
 443                         }
 444
 445                         tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep,
 446                                         net, head, port);
 447                         if (!tb) {
 448                                 spin_unlock(&head->lock);
 449                                 break;
 450                         }
 451                         tb->fastreuse = -1;
 452                         goto ok;
 453
 454                 next_port:
 455                         spin_unlock(&head->lock);
 456                 }
 457                 local_bh_enable();
 458
 459                 return -EADDRNOTAVAIL;
 460
 461 ok:
 462                 hint += i;
 463
 464                 /* Head lock still held and bh's disabled */
 465                 inet_bind_hash(sk, tb, port);
 466                 if (sk_unhashed(sk)) {
 467                         inet_sk(sk)->sport = htons(port);
 468                         hash(sk);
 469                 }
 470                 spin_unlock(&head->lock);
 471
 472                 if (tw) {
 473                         inet_twsk_deschedule(tw, death_row);
 474                         inet_twsk_put(tw);
 475                 }
 476
 477                 ret = 0;
 478                 goto out;
 479         }
 480
 481         head = &hinfo->bhash[inet_bhashfn(snum, hinfo->bhash_size)];
 482         tb  = inet_csk(sk)->icsk_bind_hash;
 483         spin_lock_bh(&head->lock);
 484         if (sk_head(&tb->owners) == sk && !sk->sk_bind_node.next) {
 485                 hash(sk);
 486                 spin_unlock_bh(&head->lock);
 487                 return 0;
 488         } else {
 489                 spin_unlock(&head->lock);
 490                 /* No definite answer... Walk to established hash table */
 491                 ret = check_established(death_row, sk, snum, NULL);
 492 out:
 493                 local_bh_enable();
 494                 return ret;
 495         }
 496 }
 497 EXPORT_SYMBOL_GPL(__inet_hash_connect);
 498
 499 /*
 500  * Bind a port for a connect operation and hash it.
 501  */
 502 int inet_hash_connect(struct inet_timewait_death_row *death_row,
 503                       struct sock *sk)
 504 {
 505         return __inet_hash_connect(death_row, sk, inet_sk_port_offset(sk),
 506                         __inet_check_established, __inet_hash_nolisten);
 507 }
 508
 509 EXPORT_SYMBOL_GPL(inet_hash_connect);