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)->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)->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)->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
 103 EXPORT_SYMBOL(inet_put_port);
 104
 105 void __inet_inherit_port(struct sock *sk, struct sock *child)
 106 {
 107         struct inet_hashinfo *table = sk->sk_prot->h.hashinfo;
 108         const int bhash = inet_bhashfn(sock_net(sk), inet_sk(child)->num,
 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         sk_add_bind_node(child, &tb->owners);
 116         inet_csk(child)->icsk_bind_hash = tb;
 117         spin_unlock(&head->lock);
 118 }
 119
 120 EXPORT_SYMBOL_GPL(__inet_inherit_port);
 121
 122 static inline int compute_score(struct sock *sk, struct net *net,
 123                                 const unsigned short hnum, const __be32 daddr,
 124                                 const int dif)
 125 {
 126         int score = -1;
 127         struct inet_sock *inet = inet_sk(sk);
 128
 129         if (net_eq(sock_net(sk), net) && inet->num == hnum &&
 130                         !ipv6_only_sock(sk)) {
 131                 __be32 rcv_saddr = inet->rcv_saddr;
 132                 score = sk->sk_family == PF_INET ? 1 : 0;
 133                 if (rcv_saddr) {
 134                         if (rcv_saddr != daddr)
 135                                 return -1;
 136                         score += 2;
 137                 }
 138                 if (sk->sk_bound_dev_if) {
 139                         if (sk->sk_bound_dev_if != dif)
 140                                 return -1;
 141                         score += 2;
 142                 }
 143         }
 144         return score;
 145 }
 146
 147 /*
 148  * Don't inline this cruft. Here are some nice properties to exploit here. The
 149  * BSD API does not allow a listening sock to specify the remote port nor the
 150  * remote address for the connection. So always assume those are both
 151  * wildcarded during the search since they can never be otherwise.
 152  */
 153
 154
 155 struct sock *__inet_lookup_listener(struct net *net,
 156                                     struct inet_hashinfo *hashinfo,
 157                                     const __be32 daddr, const unsigned short hnum,
 158                                     const int dif)
 159 {
 160         struct sock *sk, *result;
 161         struct hlist_nulls_node *node;
 162         unsigned int hash = inet_lhashfn(net, hnum);
 163         struct inet_listen_hashbucket *ilb = &hashinfo->listening_hash[hash];
 164         int score, hiscore;
 165
 166         rcu_read_lock();
 167 begin:
 168         result = NULL;
 169         hiscore = -1;
 170         sk_nulls_for_each_rcu(sk, node, &ilb->head) {
 171                 score = compute_score(sk, net, hnum, daddr, dif);
 172                 if (score > hiscore) {
 173                         result = sk;
 174                         hiscore = score;
 175                 }
 176         }
 177         /*
 178          * if the nulls value we got at the end of this lookup is
 179          * not the expected one, we must restart lookup.
 180          * We probably met an item that was moved to another chain.
 181          */
 182         if (get_nulls_value(node) != hash + LISTENING_NULLS_BASE)
 183                 goto begin;
 184         if (result) {
 185                 if (unlikely(!atomic_inc_not_zero(&result->sk_refcnt)))
 186                         result = NULL;
 187                 else if (unlikely(compute_score(result, net, hnum, daddr,
 188                                   dif) < hiscore)) {
 189                         sock_put(result);
 190                         goto begin;
 191                 }
 192         }
 193         rcu_read_unlock();
 194         return result;
 195 }
 196 EXPORT_SYMBOL_GPL(__inet_lookup_listener);
 197
 198 struct sock * __inet_lookup_established(struct net *net,
 199                                   struct inet_hashinfo *hashinfo,
 200                                   const __be32 saddr, const __be16 sport,
 201                                   const __be32 daddr, const u16 hnum,
 202                                   const int dif)
 203 {
 204         INET_ADDR_COOKIE(acookie, saddr, daddr)
 205         const __portpair ports = INET_COMBINED_PORTS(sport, hnum);
 206         struct sock *sk;
 207         const struct hlist_nulls_node *node;
 208         /* Optimize here for direct hit, only listening connections can
 209          * have wildcards anyways.
 210          */
 211         unsigned int hash = inet_ehashfn(net, daddr, hnum, saddr, sport);
 212         unsigned int slot = hash & (hashinfo->ehash_size - 1);
 213         struct inet_ehash_bucket *head = &hashinfo->ehash[slot];
 214
 215         rcu_read_lock();
 216 begin:
 217         sk_nulls_for_each_rcu(sk, node, &head->chain) {
 218                 if (INET_MATCH(sk, net, hash, acookie,
 219                                         saddr, daddr, ports, dif)) {
 220                         if (unlikely(!atomic_inc_not_zero(&sk->sk_refcnt)))
 221                                 goto begintw;
 222                         if (unlikely(!INET_MATCH(sk, net, hash, acookie,
 223                                 saddr, daddr, ports, dif))) {
 224                                 sock_put(sk);
 225                                 goto begin;
 226                         }
 227                         goto out;
 228                 }
 229         }
 230         /*
 231          * if the nulls value we got at the end of this lookup is
 232          * not the expected one, we must restart lookup.
 233          * We probably met an item that was moved to another chain.
 234          */
 235         if (get_nulls_value(node) != slot)
 236                 goto begin;
 237
 238 begintw:
 239         /* Must check for a TIME_WAIT'er before going to listener hash. */
 240         sk_nulls_for_each_rcu(sk, node, &head->twchain) {
 241                 if (INET_TW_MATCH(sk, net, hash, acookie,
 242                                         saddr, daddr, ports, dif)) {
 243                         if (unlikely(!atomic_inc_not_zero(&sk->sk_refcnt))) {
 244                                 sk = NULL;
 245                                 goto out;
 246                         }
 247                         if (unlikely(!INET_TW_MATCH(sk, net, hash, acookie,
 248                                  saddr, daddr, ports, dif))) {
 249                                 sock_put(sk);
 250                                 goto begintw;
 251                         }
 252                         goto out;
 253                 }
 254         }
 255         /*
 256          * if the nulls value we got at the end of this lookup is
 257          * not the expected one, we must restart lookup.
 258          * We probably met an item that was moved to another chain.
 259          */
 260         if (get_nulls_value(node) != slot)
 261                 goto begintw;
 262         sk = NULL;
 263 out:
 264         rcu_read_unlock();
 265         return sk;
 266 }
 267 EXPORT_SYMBOL_GPL(__inet_lookup_established);
 268
 269 /* called with local bh disabled */
 270 static int __inet_check_established(struct inet_timewait_death_row *death_row,
 271                                     struct sock *sk, __u16 lport,
 272                                     struct inet_timewait_sock **twp)
 273 {
 274         struct inet_hashinfo *hinfo = death_row->hashinfo;
 275         struct inet_sock *inet = inet_sk(sk);
 276         __be32 daddr = inet->rcv_saddr;
 277         __be32 saddr = inet->daddr;
 278         int dif = sk->sk_bound_dev_if;
 279         INET_ADDR_COOKIE(acookie, saddr, daddr)
 280         const __portpair ports = INET_COMBINED_PORTS(inet->dport, lport);
 281         struct net *net = sock_net(sk);
 282         unsigned int hash = inet_ehashfn(net, daddr, lport, saddr, inet->dport);
 283         struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);
 284         spinlock_t *lock = inet_ehash_lockp(hinfo, hash);
 285         struct sock *sk2;
 286         const struct hlist_nulls_node *node;
 287         struct inet_timewait_sock *tw;
 288
 289         spin_lock(lock);
 290
 291         /* Check TIME-WAIT sockets first. */
 292         sk_nulls_for_each(sk2, node, &head->twchain) {
 293                 tw = inet_twsk(sk2);
 294
 295                 if (INET_TW_MATCH(sk2, net, hash, acookie,
 296                                         saddr, daddr, ports, dif)) {
 297                         if (twsk_unique(sk, sk2, twp))
 298                                 goto unique;
 299                         else
 300                                 goto not_unique;
 301                 }
 302         }
 303         tw = NULL;
 304
 305         /* And established part... */
 306         sk_nulls_for_each(sk2, node, &head->chain) {
 307                 if (INET_MATCH(sk2, net, hash, acookie,
 308                                         saddr, daddr, ports, dif))
 309                         goto not_unique;
 310         }
 311
 312 unique:
 313         /* Must record num and sport now. Otherwise we will see
 314          * in hash table socket with a funny identity. */
 315         inet->num = lport;
 316         inet->sport = htons(lport);
 317         sk->sk_hash = hash;
 318         WARN_ON(!sk_unhashed(sk));
 319         __sk_nulls_add_node_rcu(sk, &head->chain);
 320         spin_unlock(lock);
 321         sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
 322
 323         if (twp) {
 324                 *twp = tw;
 325                 NET_INC_STATS_BH(net, LINUX_MIB_TIMEWAITRECYCLED);
 326         } else if (tw) {
 327                 /* Silly. Should hash-dance instead... */
 328                 inet_twsk_deschedule(tw, death_row);
 329                 NET_INC_STATS_BH(net, LINUX_MIB_TIMEWAITRECYCLED);
 330
 331                 inet_twsk_put(tw);
 332         }
 333
 334         return 0;
 335
 336 not_unique:
 337         spin_unlock(lock);
 338         return -EADDRNOTAVAIL;
 339 }
 340
 341 static inline u32 inet_sk_port_offset(const struct sock *sk)
 342 {
 343         const struct inet_sock *inet = inet_sk(sk);
 344         return secure_ipv4_port_ephemeral(inet->rcv_saddr, inet->daddr,
 345                                           inet->dport);
 346 }
 347
 348 void __inet_hash_nolisten(struct sock *sk)
 349 {
 350         struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
 351         struct hlist_nulls_head *list;
 352         spinlock_t *lock;
 353         struct inet_ehash_bucket *head;
 354
 355         WARN_ON(!sk_unhashed(sk));
 356
 357         sk->sk_hash = inet_sk_ehashfn(sk);
 358         head = inet_ehash_bucket(hashinfo, sk->sk_hash);
 359         list = &head->chain;
 360         lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
 361
 362         spin_lock(lock);
 363         __sk_nulls_add_node_rcu(sk, list);
 364         spin_unlock(lock);
 365         sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
 366 }
 367 EXPORT_SYMBOL_GPL(__inet_hash_nolisten);
 368
 369 static void __inet_hash(struct sock *sk)
 370 {
 371         struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
 372         struct inet_listen_hashbucket *ilb;
 373
 374         if (sk->sk_state != TCP_LISTEN) {
 375                 __inet_hash_nolisten(sk);
 376                 return;
 377         }
 378
 379         WARN_ON(!sk_unhashed(sk));
 380         ilb = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)];
 381
 382         spin_lock(&ilb->lock);
 383         __sk_nulls_add_node_rcu(sk, &ilb->head);
 384         sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
 385         spin_unlock(&ilb->lock);
 386 }
 387
 388 void inet_hash(struct sock *sk)
 389 {
 390         if (sk->sk_state != TCP_CLOSE) {
 391                 local_bh_disable();
 392                 __inet_hash(sk);
 393                 local_bh_enable();
 394         }
 395 }
 396 EXPORT_SYMBOL_GPL(inet_hash);
 397
 398 void inet_unhash(struct sock *sk)
 399 {
 400         struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
 401         spinlock_t *lock;
 402         int done;
 403
 404         if (sk_unhashed(sk))
 405                 return;
 406
 407         if (sk->sk_state == TCP_LISTEN)
 408                 lock = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)].lock;
 409         else
 410                 lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
 411
 412         spin_lock_bh(lock);
 413         done =__sk_nulls_del_node_init_rcu(sk);
 414         if (done)
 415                 sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
 416         spin_unlock_bh(lock);
 417 }
 418 EXPORT_SYMBOL_GPL(inet_unhash);
 419
 420 int __inet_hash_connect(struct inet_timewait_death_row *death_row,
 421                 struct sock *sk, u32 port_offset,
 422                 int (*check_established)(struct inet_timewait_death_row *,
 423                         struct sock *, __u16, struct inet_timewait_sock **),
 424                 void (*hash)(struct sock *sk))
 425 {
 426         struct inet_hashinfo *hinfo = death_row->hashinfo;
 427         const unsigned short snum = inet_sk(sk)->num;
 428         struct inet_bind_hashbucket *head;
 429         struct inet_bind_bucket *tb;
 430         int ret;
 431         struct net *net = sock_net(sk);
 432
 433         if (!snum) {
 434                 int i, remaining, low, high, port;
 435                 static u32 hint;
 436                 u32 offset = hint + port_offset;
 437                 struct hlist_node *node;
 438                 struct inet_timewait_sock *tw = NULL;
 439
 440                 inet_get_local_port_range(&low, &high);
 441                 remaining = (high - low) + 1;
 442
 443                 local_bh_disable();
 444                 for (i = 1; i <= remaining; i++) {
 445                         port = low + (i + offset) % remaining;
 446                         head = &hinfo->bhash[inet_bhashfn(net, port,
 447                                         hinfo->bhash_size)];
 448                         spin_lock(&head->lock);
 449
 450                         /* Does not bother with rcv_saddr checks,
 451                          * because the established check is already
 452                          * unique enough.
 453                          */
 454                         inet_bind_bucket_for_each(tb, node, &head->chain) {
 455                                 if (ib_net(tb) == net && tb->port == port) {
 456                                         if (tb->fastreuse >= 0)
 457                                                 goto next_port;
 458                                         WARN_ON(hlist_empty(&tb->owners));
 459                                         if (!check_established(death_row, sk,
 460                                                                 port, &tw))
 461                                                 goto ok;
 462                                         goto next_port;
 463                                 }
 464                         }
 465
 466                         tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep,
 467                                         net, head, port);
 468                         if (!tb) {
 469                                 spin_unlock(&head->lock);
 470                                 break;
 471                         }
 472                         tb->fastreuse = -1;
 473                         goto ok;
 474
 475                 next_port:
 476                         spin_unlock(&head->lock);
 477                 }
 478                 local_bh_enable();
 479
 480                 return -EADDRNOTAVAIL;
 481
 482 ok:
 483                 hint += i;
 484
 485                 /* Head lock still held and bh's disabled */
 486                 inet_bind_hash(sk, tb, port);
 487                 if (sk_unhashed(sk)) {
 488                         inet_sk(sk)->sport = htons(port);
 489                         hash(sk);
 490                 }
 491                 spin_unlock(&head->lock);
 492
 493                 if (tw) {
 494                         inet_twsk_deschedule(tw, death_row);
 495                         inet_twsk_put(tw);
 496                 }
 497
 498                 ret = 0;
 499                 goto out;
 500         }
 501
 502         head = &hinfo->bhash[inet_bhashfn(net, snum, hinfo->bhash_size)];
 503         tb  = inet_csk(sk)->icsk_bind_hash;
 504         spin_lock_bh(&head->lock);
 505         if (sk_head(&tb->owners) == sk && !sk->sk_bind_node.next) {
 506                 hash(sk);
 507                 spin_unlock_bh(&head->lock);
 508                 return 0;
 509         } else {
 510                 spin_unlock(&head->lock);
 511                 /* No definite answer... Walk to established hash table */
 512                 ret = check_established(death_row, sk, snum, NULL);
 513 out:
 514                 local_bh_enable();
 515                 return ret;
 516         }
 517 }
 518
 519 /*
 520  * Bind a port for a connect operation and hash it.
 521  */
 522 int inet_hash_connect(struct inet_timewait_death_row *death_row,
 523                       struct sock *sk)
 524 {
 525         return __inet_hash_connect(death_row, sk, inet_sk_port_offset(sk),
 526                         __inet_check_established, __inet_hash_nolisten);
 527 }
 528
 529 EXPORT_SYMBOL_GPL(inet_hash_connect);
 530
 531 void inet_hashinfo_init(struct inet_hashinfo *h)
 532 {
 533         int i;
 534
 535         atomic_set(&h->bsockets, 0);
 536         for (i = 0; i < INET_LHTABLE_SIZE; i++) {
 537                 spin_lock_init(&h->listening_hash[i].lock);
 538                 INIT_HLIST_NULLS_HEAD(&h->listening_hash[i].head,
 539                                       i + LISTENING_NULLS_BASE);
 540                 }
 541 }
 542
 543 EXPORT_SYMBOL_GPL(inet_hashinfo_init);