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
 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)->inet_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->inet_num == hnum &&
 130                         !ipv6_only_sock(sk)) {
 131                 __be32 rcv_saddr = inet->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_mask;
 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->inet_rcv_saddr;
 277         __be32 saddr = inet->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->inet_dport, lport);
 281         struct net *net = sock_net(sk);
 282         unsigned int hash = inet_ehashfn(net, daddr, lport,
 283                                          saddr, inet->inet_dport);
 284         struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);
 285         spinlock_t *lock = inet_ehash_lockp(hinfo, hash);
 286         struct sock *sk2;
 287         const struct hlist_nulls_node *node;
 288         struct inet_timewait_sock *tw;
 289         int twrefcnt = 0;
 290
 291         spin_lock(lock);
 292
 293         /* Check TIME-WAIT sockets first. */
 294         sk_nulls_for_each(sk2, node, &head->twchain) {
 295                 tw = inet_twsk(sk2);
 296
 297                 if (INET_TW_MATCH(sk2, net, hash, acookie,
 298                                         saddr, daddr, ports, dif)) {
 299                         if (twsk_unique(sk, sk2, twp))
 300                                 goto unique;
 301                         else
 302                                 goto not_unique;
 303                 }
 304         }
 305         tw = NULL;
 306
 307         /* And established part... */
 308         sk_nulls_for_each(sk2, node, &head->chain) {
 309                 if (INET_MATCH(sk2, net, hash, acookie,
 310                                         saddr, daddr, ports, dif))
 311                         goto not_unique;
 312         }
 313
 314 unique:
 315         /* Must record num and sport now. Otherwise we will see
 316          * in hash table socket with a funny identity. */
 317         inet->inet_num = lport;
 318         inet->inet_sport = htons(lport);
 319         sk->sk_hash = hash;
 320         WARN_ON(!sk_unhashed(sk));
 321         __sk_nulls_add_node_rcu(sk, &head->chain);
 322         if (tw) {
 323                 twrefcnt = inet_twsk_unhash(tw);
 324                 NET_INC_STATS_BH(net, LINUX_MIB_TIMEWAITRECYCLED);
 325         }
 326         spin_unlock(lock);
 327         if (twrefcnt)
 328                 inet_twsk_put(tw);
 329         sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
 330
 331         if (twp) {
 332                 *twp = tw;
 333         } else if (tw) {
 334                 /* Silly. Should hash-dance instead... */
 335                 inet_twsk_deschedule(tw, death_row);
 336
 337                 inet_twsk_put(tw);
 338         }
 339         return 0;
 340
 341 not_unique:
 342         spin_unlock(lock);
 343         return -EADDRNOTAVAIL;
 344 }
 345
 346 static inline u32 inet_sk_port_offset(const struct sock *sk)
 347 {
 348         const struct inet_sock *inet = inet_sk(sk);
 349         return secure_ipv4_port_ephemeral(inet->inet_rcv_saddr,
 350                                           inet->inet_daddr,
 351                                           inet->inet_dport);
 352 }
 353
 354 void __inet_hash_nolisten(struct sock *sk)
 355 {
 356         struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
 357         struct hlist_nulls_head *list;
 358         spinlock_t *lock;
 359         struct inet_ehash_bucket *head;
 360
 361         WARN_ON(!sk_unhashed(sk));
 362
 363         sk->sk_hash = inet_sk_ehashfn(sk);
 364         head = inet_ehash_bucket(hashinfo, sk->sk_hash);
 365         list = &head->chain;
 366         lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
 367
 368         spin_lock(lock);
 369         __sk_nulls_add_node_rcu(sk, list);
 370         spin_unlock(lock);
 371         sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
 372 }
 373 EXPORT_SYMBOL_GPL(__inet_hash_nolisten);
 374
 375 static void __inet_hash(struct sock *sk)
 376 {
 377         struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
 378         struct inet_listen_hashbucket *ilb;
 379
 380         if (sk->sk_state != TCP_LISTEN) {
 381                 __inet_hash_nolisten(sk);
 382                 return;
 383         }
 384
 385         WARN_ON(!sk_unhashed(sk));
 386         ilb = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)];
 387
 388         spin_lock(&ilb->lock);
 389         __sk_nulls_add_node_rcu(sk, &ilb->head);
 390         sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
 391         spin_unlock(&ilb->lock);
 392 }
 393
 394 void inet_hash(struct sock *sk)
 395 {
 396         if (sk->sk_state != TCP_CLOSE) {
 397                 local_bh_disable();
 398                 __inet_hash(sk);
 399                 local_bh_enable();
 400         }
 401 }
 402 EXPORT_SYMBOL_GPL(inet_hash);
 403
 404 void inet_unhash(struct sock *sk)
 405 {
 406         struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
 407         spinlock_t *lock;
 408         int done;
 409
 410         if (sk_unhashed(sk))
 411                 return;
 412
 413         if (sk->sk_state == TCP_LISTEN)
 414                 lock = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)].lock;
 415         else
 416                 lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
 417
 418         spin_lock_bh(lock);
 419         done =__sk_nulls_del_node_init_rcu(sk);
 420         if (done)
 421                 sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
 422         spin_unlock_bh(lock);
 423 }
 424 EXPORT_SYMBOL_GPL(inet_unhash);
 425
 426 int __inet_hash_connect(struct inet_timewait_death_row *death_row,
 427                 struct sock *sk, u32 port_offset,
 428                 int (*check_established)(struct inet_timewait_death_row *,
 429                         struct sock *, __u16, struct inet_timewait_sock **),
 430                 void (*hash)(struct sock *sk))
 431 {
 432         struct inet_hashinfo *hinfo = death_row->hashinfo;
 433         const unsigned short snum = inet_sk(sk)->inet_num;
 434         struct inet_bind_hashbucket *head;
 435         struct inet_bind_bucket *tb;
 436         int ret;
 437         struct net *net = sock_net(sk);
 438
 439         if (!snum) {
 440                 int i, remaining, low, high, port;
 441                 static u32 hint;
 442                 u32 offset = hint + port_offset;
 443                 struct hlist_node *node;
 444                 struct inet_timewait_sock *tw = NULL;
 445
 446                 inet_get_local_port_range(&low, &high);
 447                 remaining = (high - low) + 1;
 448
 449                 local_bh_disable();
 450                 for (i = 1; i <= remaining; i++) {
 451                         port = low + (i + offset) % remaining;
 452                         head = &hinfo->bhash[inet_bhashfn(net, port,
 453                                         hinfo->bhash_size)];
 454                         spin_lock(&head->lock);
 455
 456                         /* Does not bother with rcv_saddr checks,
 457                          * because the established check is already
 458                          * unique enough.
 459                          */
 460                         inet_bind_bucket_for_each(tb, node, &head->chain) {
 461                                 if (net_eq(ib_net(tb), net) &&
 462                                     tb->port == port) {
 463                                         if (tb->fastreuse >= 0)
 464                                                 goto next_port;
 465                                         WARN_ON(hlist_empty(&tb->owners));
 466                                         if (!check_established(death_row, sk,
 467                                                                 port, &tw))
 468                                                 goto ok;
 469                                         goto next_port;
 470                                 }
 471                         }
 472
 473                         tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep,
 474                                         net, head, port);
 475                         if (!tb) {
 476                                 spin_unlock(&head->lock);
 477                                 break;
 478                         }
 479                         tb->fastreuse = -1;
 480                         goto ok;
 481
 482                 next_port:
 483                         spin_unlock(&head->lock);
 484                 }
 485                 local_bh_enable();
 486
 487                 return -EADDRNOTAVAIL;
 488
 489 ok:
 490                 hint += i;
 491
 492                 /* Head lock still held and bh's disabled */
 493                 inet_bind_hash(sk, tb, port);
 494                 if (sk_unhashed(sk)) {
 495                         inet_sk(sk)->inet_sport = htons(port);
 496                         hash(sk);
 497                 }
 498                 spin_unlock(&head->lock);
 499
 500                 if (tw) {
 501                         inet_twsk_deschedule(tw, death_row);
 502                         inet_twsk_put(tw);
 503                 }
 504
 505                 ret = 0;
 506                 goto out;
 507         }
 508
 509         head = &hinfo->bhash[inet_bhashfn(net, snum, hinfo->bhash_size)];
 510         tb  = inet_csk(sk)->icsk_bind_hash;
 511         spin_lock_bh(&head->lock);
 512         if (sk_head(&tb->owners) == sk && !sk->sk_bind_node.next) {
 513                 hash(sk);
 514                 spin_unlock_bh(&head->lock);
 515                 return 0;
 516         } else {
 517                 spin_unlock(&head->lock);
 518                 /* No definite answer... Walk to established hash table */
 519                 ret = check_established(death_row, sk, snum, NULL);
 520 out:
 521                 local_bh_enable();
 522                 return ret;
 523         }
 524 }
 525
 526 /*
 527  * Bind a port for a connect operation and hash it.
 528  */
 529 int inet_hash_connect(struct inet_timewait_death_row *death_row,
 530                       struct sock *sk)
 531 {
 532         return __inet_hash_connect(death_row, sk, inet_sk_port_offset(sk),
 533                         __inet_check_established, __inet_hash_nolisten);
 534 }
 535
 536 EXPORT_SYMBOL_GPL(inet_hash_connect);
 537
 538 void inet_hashinfo_init(struct inet_hashinfo *h)
 539 {
 540         int i;
 541
 542         atomic_set(&h->bsockets, 0);
 543         for (i = 0; i < INET_LHTABLE_SIZE; i++) {
 544                 spin_lock_init(&h->listening_hash[i].lock);
 545                 INIT_HLIST_NULLS_HEAD(&h->listening_hash[i].head,
 546                                       i + LISTENING_NULLS_BASE);
 547                 }
 548 }
 549
 550 EXPORT_SYMBOL_GPL(inet_hashinfo_init);