SAFE public projects git trees. - safe/jmp/linux-2.6/blob - 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 /*
 114  * Don't inline this cruft. Here are some nice properties to exploit here. The
 115  * BSD API does not allow a listening sock to specify the remote port nor the
 116  * remote address for the connection. So always assume those are both
 117  * wildcarded during the search since they can never be otherwise.
 118  */
 119 static struct sock *inet_lookup_listener_slow(struct net *net,
 120                                               const struct hlist_head *head,
 121                                               const __be32 daddr,
 122                                               const unsigned short hnum,
 123                                               const int dif)
 124 {
 125         struct sock *result = NULL, *sk;
 126         const struct hlist_node *node;
 127         int hiscore = -1;
 128
 129         sk_for_each(sk, node, head) {
 130                 const struct inet_sock *inet = inet_sk(sk);
 131
 132                 if (net_eq(sock_net(sk), net) && inet->num == hnum &&
 133                                 !ipv6_only_sock(sk)) {
 134                         const __be32 rcv_saddr = inet->rcv_saddr;
 135                         int score = sk->sk_family == PF_INET ? 1 : 0;
 136
 137                         if (rcv_saddr) {
 138                                 if (rcv_saddr != daddr)
 139                                         continue;
 140                                 score += 2;
 141                         }
 142                         if (sk->sk_bound_dev_if) {
 143                                 if (sk->sk_bound_dev_if != dif)
 144                                         continue;
 145                                 score += 2;
 146                         }
 147                         if (score == 5)
 148                                 return sk;
 149                         if (score > hiscore) {
 150                                 hiscore = score;
 151                                 result  = sk;
 152                         }
 153                 }
 154         }
 155         return result;
 156 }
 157
 158 /* Optimize the common listener case. */
 159 struct sock *__inet_lookup_listener(struct net *net,
 160                                     struct inet_hashinfo *hashinfo,
 161                                     const __be32 daddr, const unsigned short hnum,
 162                                     const int dif)
 163 {
 164         struct sock *sk = NULL;
 165         struct inet_listen_hashbucket *ilb;
 166
 167         ilb = &hashinfo->listening_hash[inet_lhashfn(net, hnum)];
 168         spin_lock(&ilb->lock);
 169         if (!hlist_empty(&ilb->head)) {
 170                 const struct inet_sock *inet = inet_sk((sk = __sk_head(&ilb->head)));
 171
 172                 if (inet->num == hnum && !sk->sk_node.next &&
 173                     (!inet->rcv_saddr || inet->rcv_saddr == daddr) &&
 174                     (sk->sk_family == PF_INET || !ipv6_only_sock(sk)) &&
 175                     !sk->sk_bound_dev_if && net_eq(sock_net(sk), net))
 176                         goto sherry_cache;
 177                 sk = inet_lookup_listener_slow(net, &ilb->head, daddr, hnum, dif);
 178         }
 179         if (sk) {
 180 sherry_cache:
 181                 sock_hold(sk);
 182         }
 183         spin_unlock(&ilb->lock);
 184         return sk;
 185 }
 186 EXPORT_SYMBOL_GPL(__inet_lookup_listener);
 187
 188 struct sock * __inet_lookup_established(struct net *net,
 189                                   struct inet_hashinfo *hashinfo,
 190                                   const __be32 saddr, const __be16 sport,
 191                                   const __be32 daddr, const u16 hnum,
 192                                   const int dif)
 193 {
 194         INET_ADDR_COOKIE(acookie, saddr, daddr)
 195         const __portpair ports = INET_COMBINED_PORTS(sport, hnum);
 196         struct sock *sk;
 197         const struct hlist_nulls_node *node;
 198         /* Optimize here for direct hit, only listening connections can
 199          * have wildcards anyways.
 200          */
 201         unsigned int hash = inet_ehashfn(net, daddr, hnum, saddr, sport);
 202         unsigned int slot = hash & (hashinfo->ehash_size - 1);
 203         struct inet_ehash_bucket *head = &hashinfo->ehash[slot];
 204
 205         rcu_read_lock();
 206 begin:
 207         sk_nulls_for_each_rcu(sk, node, &head->chain) {
 208                 if (INET_MATCH(sk, net, hash, acookie,
 209                                         saddr, daddr, ports, dif)) {
 210                         if (unlikely(!atomic_inc_not_zero(&sk->sk_refcnt)))
 211                                 goto begintw;
 212                         if (unlikely(!INET_MATCH(sk, net, hash, acookie,
 213                                 saddr, daddr, ports, dif))) {
 214                                 sock_put(sk);
 215                                 goto begin;
 216                         }
 217                         goto out;
 218                 }
 219         }
 220         /*
 221          * if the nulls value we got at the end of this lookup is
 222          * not the expected one, we must restart lookup.
 223          * We probably met an item that was moved to another chain.
 224          */
 225         if (get_nulls_value(node) != slot)
 226                 goto begin;
 227
 228 begintw:
 229         /* Must check for a TIME_WAIT'er before going to listener hash. */
 230         sk_nulls_for_each_rcu(sk, node, &head->twchain) {
 231                 if (INET_TW_MATCH(sk, net, hash, acookie,
 232                                         saddr, daddr, ports, dif)) {
 233                         if (unlikely(!atomic_inc_not_zero(&sk->sk_refcnt))) {
 234                                 sk = NULL;
 235                                 goto out;
 236                         }
 237                         if (unlikely(!INET_TW_MATCH(sk, net, hash, acookie,
 238                                  saddr, daddr, ports, dif))) {
 239                                 sock_put(sk);
 240                                 goto begintw;
 241                         }
 242                         goto out;
 243                 }
 244         }
 245         /*
 246          * if the nulls value we got at the end of this lookup is
 247          * not the expected one, we must restart lookup.
 248          * We probably met an item that was moved to another chain.
 249          */
 250         if (get_nulls_value(node) != slot)
 251                 goto begintw;
 252         sk = NULL;
 253 out:
 254         rcu_read_unlock();
 255         return sk;
 256 }
 257 EXPORT_SYMBOL_GPL(__inet_lookup_established);
 258
 259 /* called with local bh disabled */
 260 static int __inet_check_established(struct inet_timewait_death_row *death_row,
 261                                     struct sock *sk, __u16 lport,
 262                                     struct inet_timewait_sock **twp)
 263 {
 264         struct inet_hashinfo *hinfo = death_row->hashinfo;
 265         struct inet_sock *inet = inet_sk(sk);
 266         __be32 daddr = inet->rcv_saddr;
 267         __be32 saddr = inet->daddr;
 268         int dif = sk->sk_bound_dev_if;
 269         INET_ADDR_COOKIE(acookie, saddr, daddr)
 270         const __portpair ports = INET_COMBINED_PORTS(inet->dport, lport);
 271         struct net *net = sock_net(sk);
 272         unsigned int hash = inet_ehashfn(net, daddr, lport, saddr, inet->dport);
 273         struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);
 274         rwlock_t *lock = inet_ehash_lockp(hinfo, hash);
 275         struct sock *sk2;
 276         const struct hlist_nulls_node *node;
 277         struct inet_timewait_sock *tw;
 278
 279         prefetch(head->chain.first);
 280         write_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         sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
 312         write_unlock(lock);
 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         write_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         rwlock_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         write_lock(lock);
 354         __sk_nulls_add_node_rcu(sk, list);
 355         sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
 356         write_unlock(lock);
 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_add_node(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
 393         if (sk_unhashed(sk))
 394                 return;
 395
 396         if (sk->sk_state == TCP_LISTEN) {
 397                 struct inet_listen_hashbucket *ilb;
 398
 399                 ilb = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)];
 400                 spin_lock_bh(&ilb->lock);
 401                 if (__sk_del_node_init(sk))
 402                         sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
 403                 spin_unlock_bh(&ilb->lock);
 404         } else {
 405                 rwlock_t *lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
 406
 407                 write_lock_bh(lock);
 408                 if (__sk_nulls_del_node_init_rcu(sk))
 409                         sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
 410                 write_unlock_bh(lock);
 411         }
 412 }
 413 EXPORT_SYMBOL_GPL(inet_unhash);
 414
 415 int __inet_hash_connect(struct inet_timewait_death_row *death_row,
 416                 struct sock *sk, u32 port_offset,
 417                 int (*check_established)(struct inet_timewait_death_row *,
 418                         struct sock *, __u16, struct inet_timewait_sock **),
 419                 void (*hash)(struct sock *sk))
 420 {
 421         struct inet_hashinfo *hinfo = death_row->hashinfo;
 422         const unsigned short snum = inet_sk(sk)->num;
 423         struct inet_bind_hashbucket *head;
 424         struct inet_bind_bucket *tb;
 425         int ret;
 426         struct net *net = sock_net(sk);
 427
 428         if (!snum) {
 429                 int i, remaining, low, high, port;
 430                 static u32 hint;
 431                 u32 offset = hint + port_offset;
 432                 struct hlist_node *node;
 433                 struct inet_timewait_sock *tw = NULL;
 434
 435                 inet_get_local_port_range(&low, &high);
 436                 remaining = (high - low) + 1;
 437
 438                 local_bh_disable();
 439                 for (i = 1; i <= remaining; i++) {
 440                         port = low + (i + offset) % remaining;
 441                         head = &hinfo->bhash[inet_bhashfn(net, port,
 442                                         hinfo->bhash_size)];
 443                         spin_lock(&head->lock);
 444
 445                         /* Does not bother with rcv_saddr checks,
 446                          * because the established check is already
 447                          * unique enough.
 448                          */
 449                         inet_bind_bucket_for_each(tb, node, &head->chain) {
 450                                 if (ib_net(tb) == net && tb->port == port) {
 451                                         WARN_ON(hlist_empty(&tb->owners));
 452                                         if (tb->fastreuse >= 0)
 453                                                 goto next_port;
 454                                         if (!check_established(death_row, sk,
 455                                                                 port, &tw))
 456                                                 goto ok;
 457                                         goto next_port;
 458                                 }
 459                         }
 460
 461                         tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep,
 462                                         net, head, port);
 463                         if (!tb) {
 464                                 spin_unlock(&head->lock);
 465                                 break;
 466                         }
 467                         tb->fastreuse = -1;
 468                         goto ok;
 469
 470                 next_port:
 471                         spin_unlock(&head->lock);
 472                 }
 473                 local_bh_enable();
 474
 475                 return -EADDRNOTAVAIL;
 476
 477 ok:
 478                 hint += i;
 479
 480                 /* Head lock still held and bh's disabled */
 481                 inet_bind_hash(sk, tb, port);
 482                 if (sk_unhashed(sk)) {
 483                         inet_sk(sk)->sport = htons(port);
 484                         hash(sk);
 485                 }
 486                 spin_unlock(&head->lock);
 487
 488                 if (tw) {
 489                         inet_twsk_deschedule(tw, death_row);
 490                         inet_twsk_put(tw);
 491                 }
 492
 493                 ret = 0;
 494                 goto out;
 495         }
 496
 497         head = &hinfo->bhash[inet_bhashfn(net, snum, hinfo->bhash_size)];
 498         tb  = inet_csk(sk)->icsk_bind_hash;
 499         spin_lock_bh(&head->lock);
 500         if (sk_head(&tb->owners) == sk && !sk->sk_bind_node.next) {
 501                 hash(sk);
 502                 spin_unlock_bh(&head->lock);
 503                 return 0;
 504         } else {
 505                 spin_unlock(&head->lock);
 506                 /* No definite answer... Walk to established hash table */
 507                 ret = check_established(death_row, sk, snum, NULL);
 508 out:
 509                 local_bh_enable();
 510                 return ret;
 511         }
 512 }
 513
 514 /*
 515  * Bind a port for a connect operation and hash it.
 516  */
 517 int inet_hash_connect(struct inet_timewait_death_row *death_row,
 518                       struct sock *sk)
 519 {
 520         return __inet_hash_connect(death_row, sk, inet_sk_port_offset(sk),
 521                         __inet_check_established, __inet_hash_nolisten);
 522 }
 523
 524 EXPORT_SYMBOL_GPL(inet_hash_connect);
 525
 526 void inet_hashinfo_init(struct inet_hashinfo *h)
 527 {
 528         int i;
 529
 530         for (i = 0; i < INET_LHTABLE_SIZE; i++)
 531                 spin_lock_init(&h->listening_hash[i].lock);
 532 }
 533
 534 EXPORT_SYMBOL_GPL(inet_hashinfo_init);