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 #include <linux/vmalloc.h>
  22
  23 #include <net/addrconf.h>
  24 #include <net/inet_connection_sock.h>
  25 #include <net/inet_hashtables.h>
  26 #if IS_ENABLED(CONFIG_IPV6)
  27 #include <net/inet6_hashtables.h>
  28 #endif
  29 #include <net/secure_seq.h>
  30 #include <net/ip.h>
  31 #include <net/tcp.h>
  32 #include <net/sock_reuseport.h>
  33
  34 static u32 inet_ehashfn(const struct net *net, const __be32 laddr,
  35                         const __u16 lport, const __be32 faddr,
  36                         const __be16 fport)
  37 {
  38         static u32 inet_ehash_secret __read_mostly;
  39
  40         net_get_random_once(&inet_ehash_secret, sizeof(inet_ehash_secret));
  41
  42         return __inet_ehashfn(laddr, lport, faddr, fport,
  43                               inet_ehash_secret + net_hash_mix(net));
  44 }
  45
  46 /* This function handles inet_sock, but also timewait and request sockets
  47  * for IPv4/IPv6.
  48  */
  49 static u32 sk_ehashfn(const struct sock *sk)
  50 {
  51 #if IS_ENABLED(CONFIG_IPV6)
  52         if (sk->sk_family == AF_INET6 &&
  53             !ipv6_addr_v4mapped(&sk->sk_v6_daddr))
  54                 return inet6_ehashfn(sock_net(sk),
  55                                      &sk->sk_v6_rcv_saddr, sk->sk_num,
  56                                      &sk->sk_v6_daddr, sk->sk_dport);
  57 #endif
  58         return inet_ehashfn(sock_net(sk),
  59                             sk->sk_rcv_saddr, sk->sk_num,
  60                             sk->sk_daddr, sk->sk_dport);
  61 }
  62
  63 /*
  64  * Allocate and initialize a new local port bind bucket.
  65  * The bindhash mutex for snum's hash chain must be held here.
  66  */
  67 struct inet_bind_bucket *inet_bind_bucket_create(struct kmem_cache *cachep,
  68                                                  struct net *net,
  69                                                  struct inet_bind_hashbucket *head,
  70                                                  const unsigned short snum)
  71 {
  72         struct inet_bind_bucket *tb = kmem_cache_alloc(cachep, GFP_ATOMIC);
  73
  74         if (tb) {
  75                 write_pnet(&tb->ib_net, net);
  76                 tb->port      = snum;
  77                 tb->fastreuse = 0;
  78                 tb->fastreuseport = 0;
  79                 INIT_HLIST_HEAD(&tb->owners);
  80                 hlist_add_head(&tb->node, &head->chain);
  81         }
  82         return tb;
  83 }
  84
  85 /*
  86  * Caller must hold hashbucket lock for this tb with local BH disabled
  87  */
  88 void inet_bind_bucket_destroy(struct kmem_cache *cachep, struct inet_bind_bucket *tb)
  89 {
  90         if (hlist_empty(&tb->owners)) {
  91                 __hlist_del(&tb->node);
  92                 kmem_cache_free(cachep, tb);
  93         }
  94 }
  95
  96 void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,
  97                     const unsigned short snum)
  98 {
  99         inet_sk(sk)->inet_num = snum;
 100         sk_add_bind_node(sk, &tb->owners);
 101         inet_csk(sk)->icsk_bind_hash = tb;
 102 }
 103
 104 /*
 105  * Get rid of any references to a local port held by the given sock.
 106  */
 107 static void __inet_put_port(struct sock *sk)
 108 {
 109         struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
 110         const int bhash = inet_bhashfn(sock_net(sk), inet_sk(sk)->inet_num,
 111                         hashinfo->bhash_size);
 112         struct inet_bind_hashbucket *head = &hashinfo->bhash[bhash];
 113         struct inet_bind_bucket *tb;
 114
 115         spin_lock(&head->lock);
 116         tb = inet_csk(sk)->icsk_bind_hash;
 117         __sk_del_bind_node(sk);
 118         inet_csk(sk)->icsk_bind_hash = NULL;
 119         inet_sk(sk)->inet_num = 0;
 120         inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb);
 121         spin_unlock(&head->lock);
 122 }
 123
 124 void inet_put_port(struct sock *sk)
 125 {
 126         local_bh_disable();
 127         __inet_put_port(sk);
 128         local_bh_enable();
 129 }
 130 EXPORT_SYMBOL(inet_put_port);
 131
 132 int __inet_inherit_port(const struct sock *sk, struct sock *child)
 133 {
 134         struct inet_hashinfo *table = sk->sk_prot->h.hashinfo;
 135         unsigned short port = inet_sk(child)->inet_num;
 136         const int bhash = inet_bhashfn(sock_net(sk), port,
 137                         table->bhash_size);
 138         struct inet_bind_hashbucket *head = &table->bhash[bhash];
 139         struct inet_bind_bucket *tb;
 140
 141         spin_lock(&head->lock);
 142         tb = inet_csk(sk)->icsk_bind_hash;
 143         if (unlikely(!tb)) {
 144                 spin_unlock(&head->lock);
 145                 return -ENOENT;
 146         }
 147         if (tb->port != port) {
 148                 /* NOTE: using tproxy and redirecting skbs to a proxy
 149                  * on a different listener port breaks the assumption
 150                  * that the listener socket's icsk_bind_hash is the same
 151                  * as that of the child socket. We have to look up or
 152                  * create a new bind bucket for the child here. */
 153                 inet_bind_bucket_for_each(tb, &head->chain) {
 154                         if (net_eq(ib_net(tb), sock_net(sk)) &&
 155                             tb->port == port)
 156                                 break;
 157                 }
 158                 if (!tb) {
 159                         tb = inet_bind_bucket_create(table->bind_bucket_cachep,
 160                                                      sock_net(sk), head, port);
 161                         if (!tb) {
 162                                 spin_unlock(&head->lock);
 163                                 return -ENOMEM;
 164                         }
 165                 }
 166                 inet_csk_update_fastreuse(tb, child);
 167         }
 168         inet_bind_hash(child, tb, port);
 169         spin_unlock(&head->lock);
 170
 171         return 0;
 172 }
 173 EXPORT_SYMBOL_GPL(__inet_inherit_port);
 174
 175 static inline int compute_score(struct sock *sk, struct net *net,
 176                                 const unsigned short hnum, const __be32 daddr,
 177                                 const int dif, const int sdif, bool exact_dif)
 178 {
 179         int score = -1;
 180         struct inet_sock *inet = inet_sk(sk);
 181
 182         if (net_eq(sock_net(sk), net) && inet->inet_num == hnum &&
 183                         !ipv6_only_sock(sk)) {
 184                 __be32 rcv_saddr = inet->inet_rcv_saddr;
 185                 score = sk->sk_family == PF_INET ? 2 : 1;
 186                 if (rcv_saddr) {
 187                         if (rcv_saddr != daddr)
 188                                 return -1;
 189                         score += 4;
 190                 }
 191                 if (sk->sk_bound_dev_if || exact_dif) {
 192                         bool dev_match = (sk->sk_bound_dev_if == dif ||
 193                                           sk->sk_bound_dev_if == sdif);
 194
 195                         if (!dev_match)
 196                                 return -1;
 197                         if (sk->sk_bound_dev_if)
 198                                 score += 4;
 199                 }
 200                 if (READ_ONCE(sk->sk_incoming_cpu) == raw_smp_processor_id())
 201                         score++;
 202         }
 203         return score;
 204 }
 205
 206 /*
 207  * Here are some nice properties to exploit here. The BSD API
 208  * does not allow a listening sock to specify the remote port nor the
 209  * remote address for the connection. So always assume those are both
 210  * wildcarded during the search since they can never be otherwise.
 211  */
 212
 213 /* called with rcu_read_lock() : No refcount taken on the socket */
 214 struct sock *__inet_lookup_listener(struct net *net,
 215                                     struct inet_hashinfo *hashinfo,
 216                                     struct sk_buff *skb, int doff,
 217                                     const __be32 saddr, __be16 sport,
 218                                     const __be32 daddr, const unsigned short hnum,
 219                                     const int dif, const int sdif)
 220 {
 221         unsigned int hash = inet_lhashfn(net, hnum);
 222         struct inet_listen_hashbucket *ilb = &hashinfo->listening_hash[hash];
 223         int score, hiscore = 0, matches = 0, reuseport = 0;
 224         bool exact_dif = inet_exact_dif_match(net, skb);
 225         struct sock *sk, *result = NULL;
 226         struct hlist_nulls_node *node;
 227         u32 phash = 0;
 228
 229         sk_nulls_for_each_rcu(sk, node, &ilb->nulls_head) {
 230                 score = compute_score(sk, net, hnum, daddr,
 231                                       dif, sdif, exact_dif);
 232                 if (score > hiscore) {
 233                         reuseport = sk->sk_reuseport;
 234                         if (reuseport) {
 235                                 phash = inet_ehashfn(net, daddr, hnum,
 236                                                      saddr, sport);
 237                                 result = reuseport_select_sock(sk, phash,
 238                                                                skb, doff);
 239                                 if (result)
 240                                         return result;
 241                                 matches = 1;
 242                         }
 243                         result = sk;
 244                         hiscore = score;
 245                 } else if (score == hiscore && reuseport) {
 246                         matches++;
 247                         if (reciprocal_scale(phash, matches) == 0)
 248                                 result = sk;
 249                         phash = next_pseudo_random32(phash);
 250                 }
 251         }
 252         return result;
 253 }
 254 EXPORT_SYMBOL_GPL(__inet_lookup_listener);
 255
 256 /* All sockets share common refcount, but have different destructors */
 257 void sock_gen_put(struct sock *sk)
 258 {
 259         if (!refcount_dec_and_test(&sk->sk_refcnt))
 260                 return;
 261
 262         if (sk->sk_state == TCP_TIME_WAIT)
 263                 inet_twsk_free(inet_twsk(sk));
 264         else if (sk->sk_state == TCP_NEW_SYN_RECV)
 265                 reqsk_free(inet_reqsk(sk));
 266         else
 267                 sk_free(sk);
 268 }
 269 EXPORT_SYMBOL_GPL(sock_gen_put);
 270
 271 void sock_edemux(struct sk_buff *skb)
 272 {
 273         sock_gen_put(skb->sk);
 274 }
 275 EXPORT_SYMBOL(sock_edemux);
 276
 277 struct sock *__inet_lookup_established(struct net *net,
 278                                   struct inet_hashinfo *hashinfo,
 279                                   const __be32 saddr, const __be16 sport,
 280                                   const __be32 daddr, const u16 hnum,
 281                                   const int dif, const int sdif)
 282 {
 283         INET_ADDR_COOKIE(acookie, saddr, daddr);
 284         const __portpair ports = INET_COMBINED_PORTS(sport, hnum);
 285         struct sock *sk;
 286         const struct hlist_nulls_node *node;
 287         /* Optimize here for direct hit, only listening connections can
 288          * have wildcards anyways.
 289          */
 290         unsigned int hash = inet_ehashfn(net, daddr, hnum, saddr, sport);
 291         unsigned int slot = hash & hashinfo->ehash_mask;
 292         struct inet_ehash_bucket *head = &hashinfo->ehash[slot];
 293
 294 begin:
 295         sk_nulls_for_each_rcu(sk, node, &head->chain) {
 296                 if (sk->sk_hash != hash)
 297                         continue;
 298                 if (likely(INET_MATCH(sk, net, acookie,
 299                                       saddr, daddr, ports, dif, sdif))) {
 300                         if (unlikely(!refcount_inc_not_zero(&sk->sk_refcnt)))
 301                                 goto out;
 302                         if (unlikely(!INET_MATCH(sk, net, acookie,
 303                                                  saddr, daddr, ports,
 304                                                  dif, sdif))) {
 305                                 sock_gen_put(sk);
 306                                 goto begin;
 307                         }
 308                         goto found;
 309                 }
 310         }
 311         /*
 312          * if the nulls value we got at the end of this lookup is
 313          * not the expected one, we must restart lookup.
 314          * We probably met an item that was moved to another chain.
 315          */
 316         if (get_nulls_value(node) != slot)
 317                 goto begin;
 318 out:
 319         sk = NULL;
 320 found:
 321         return sk;
 322 }
 323 EXPORT_SYMBOL_GPL(__inet_lookup_established);
 324
 325 /* called with local bh disabled */
 326 static int __inet_check_established(struct inet_timewait_death_row *death_row,
 327                                     struct sock *sk, __u16 lport,
 328                                     struct inet_timewait_sock **twp)
 329 {
 330         struct inet_hashinfo *hinfo = death_row->hashinfo;
 331         struct inet_sock *inet = inet_sk(sk);
 332         __be32 daddr = inet->inet_rcv_saddr;
 333         __be32 saddr = inet->inet_daddr;
 334         int dif = sk->sk_bound_dev_if;
 335         struct net *net = sock_net(sk);
 336         int sdif = l3mdev_master_ifindex_by_index(net, dif);
 337         INET_ADDR_COOKIE(acookie, saddr, daddr);
 338         const __portpair ports = INET_COMBINED_PORTS(inet->inet_dport, lport);
 339         unsigned int hash = inet_ehashfn(net, daddr, lport,
 340                                          saddr, inet->inet_dport);
 341         struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);
 342         spinlock_t *lock = inet_ehash_lockp(hinfo, hash);
 343         struct sock *sk2;
 344         const struct hlist_nulls_node *node;
 345         struct inet_timewait_sock *tw = NULL;
 346
 347         spin_lock(lock);
 348
 349         sk_nulls_for_each(sk2, node, &head->chain) {
 350                 if (sk2->sk_hash != hash)
 351                         continue;
 352
 353                 if (likely(INET_MATCH(sk2, net, acookie,
 354                                          saddr, daddr, ports, dif, sdif))) {
 355                         if (sk2->sk_state == TCP_TIME_WAIT) {
 356                                 tw = inet_twsk(sk2);
 357                                 if (twsk_unique(sk, sk2, twp))
 358                                         break;
 359                         }
 360                         goto not_unique;
 361                 }
 362         }
 363
 364         /* Must record num and sport now. Otherwise we will see
 365          * in hash table socket with a funny identity.
 366          */
 367         inet->inet_num = lport;
 368         inet->inet_sport = htons(lport);
 369         sk->sk_hash = hash;
 370         WARN_ON(!sk_unhashed(sk));
 371         __sk_nulls_add_node_rcu(sk, &head->chain);
 372         if (tw) {
 373                 sk_nulls_del_node_init_rcu((struct sock *)tw);
 374                 __NET_INC_STATS(net, LINUX_MIB_TIMEWAITRECYCLED);
 375         }
 376         spin_unlock(lock);
 377         sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
 378
 379         if (twp) {
 380                 *twp = tw;
 381         } else if (tw) {
 382                 /* Silly. Should hash-dance instead... */
 383                 inet_twsk_deschedule_put(tw);
 384         }
 385         return 0;
 386
 387 not_unique:
 388         spin_unlock(lock);
 389         return -EADDRNOTAVAIL;
 390 }
 391
 392 static u64 inet_sk_port_offset(const struct sock *sk)
 393 {
 394         const struct inet_sock *inet = inet_sk(sk);
 395
 396         return secure_ipv4_port_ephemeral(inet->inet_rcv_saddr,
 397                                           inet->inet_daddr,
 398                                           inet->inet_dport);
 399 }
 400
 401 /* Searches for an exsiting socket in the ehash bucket list.
 402  * Returns true if found, false otherwise.
 403  */
 404 static bool inet_ehash_lookup_by_sk(struct sock *sk,
 405                                     struct hlist_nulls_head *list)
 406 {
 407         const __portpair ports = INET_COMBINED_PORTS(sk->sk_dport, sk->sk_num);
 408         const int sdif = sk->sk_bound_dev_if;
 409         const int dif = sk->sk_bound_dev_if;
 410         const struct hlist_nulls_node *node;
 411         struct net *net = sock_net(sk);
 412         struct sock *esk;
 413
 414         INET_ADDR_COOKIE(acookie, sk->sk_daddr, sk->sk_rcv_saddr);
 415
 416         sk_nulls_for_each_rcu(esk, node, list) {
 417                 if (esk->sk_hash != sk->sk_hash)
 418                         continue;
 419                 if (sk->sk_family == AF_INET) {
 420                         if (unlikely(INET_MATCH(esk, net, acookie,
 421                                                 sk->sk_daddr,
 422                                                 sk->sk_rcv_saddr,
 423                                                 ports, dif, sdif))) {
 424                                 return true;
 425                         }
 426                 }
 427 #if IS_ENABLED(CONFIG_IPV6)
 428                 else if (sk->sk_family == AF_INET6) {
 429                         if (unlikely(INET6_MATCH(esk, net,
 430                                                  &sk->sk_v6_daddr,
 431                                                  &sk->sk_v6_rcv_saddr,
 432                                                  ports, dif, sdif))) {
 433                                 return true;
 434                         }
 435                 }
 436 #endif
 437         }
 438         return false;
 439 }
 440
 441 /* Insert a socket into ehash, and eventually remove another one
 442  * (The another one can be a SYN_RECV or TIMEWAIT)
 443  * If an existing socket already exists, socket sk is not inserted,
 444  * and sets found_dup_sk parameter to true.
 445  */
 446 bool inet_ehash_insert(struct sock *sk, struct sock *osk, bool *found_dup_sk)
 447 {
 448         struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
 449         struct hlist_nulls_head *list;
 450         struct inet_ehash_bucket *head;
 451         spinlock_t *lock;
 452         bool ret = true;
 453
 454         WARN_ON_ONCE(!sk_unhashed(sk));
 455
 456         sk->sk_hash = sk_ehashfn(sk);
 457         head = inet_ehash_bucket(hashinfo, sk->sk_hash);
 458         list = &head->chain;
 459         lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
 460
 461         spin_lock(lock);
 462         if (osk) {
 463                 WARN_ON_ONCE(sk->sk_hash != osk->sk_hash);
 464                 ret = sk_nulls_del_node_init_rcu(osk);
 465         } else if (found_dup_sk) {
 466                 *found_dup_sk = inet_ehash_lookup_by_sk(sk, list);
 467                 if (*found_dup_sk)
 468                         ret = false;
 469         }
 470
 471         if (ret)
 472                 __sk_nulls_add_node_rcu(sk, list);
 473
 474         spin_unlock(lock);
 475
 476         return ret;
 477 }
 478
 479 bool inet_ehash_nolisten(struct sock *sk, struct sock *osk, bool *found_dup_sk)
 480 {
 481         bool ok = inet_ehash_insert(sk, osk, found_dup_sk);
 482
 483         if (ok) {
 484                 sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
 485         } else {
 486                 percpu_counter_inc(sk->sk_prot->orphan_count);
 487                 sk->sk_state = TCP_CLOSE;
 488                 sock_set_flag(sk, SOCK_DEAD);
 489                 inet_csk_destroy_sock(sk);
 490         }
 491         return ok;
 492 }
 493 EXPORT_SYMBOL_GPL(inet_ehash_nolisten);
 494
 495 static int inet_reuseport_add_sock(struct sock *sk,
 496                                    struct inet_listen_hashbucket *ilb)
 497 {
 498         struct inet_bind_bucket *tb = inet_csk(sk)->icsk_bind_hash;
 499         const struct hlist_nulls_node *node;
 500         struct sock *sk2;
 501         kuid_t uid = sock_i_uid(sk);
 502
 503         sk_nulls_for_each_rcu(sk2, node, &ilb->nulls_head) {
 504                 if (sk2 != sk &&
 505                     sk2->sk_family == sk->sk_family &&
 506                     ipv6_only_sock(sk2) == ipv6_only_sock(sk) &&
 507                     sk2->sk_bound_dev_if == sk->sk_bound_dev_if &&
 508                     inet_csk(sk2)->icsk_bind_hash == tb &&
 509                     sk2->sk_reuseport && uid_eq(uid, sock_i_uid(sk2)) &&
 510                     inet_rcv_saddr_equal(sk, sk2, false))
 511                         return reuseport_add_sock(sk, sk2);
 512         }
 513
 514         return reuseport_alloc(sk);
 515 }
 516
 517 int __inet_hash(struct sock *sk, struct sock *osk)
 518 {
 519         struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
 520         struct inet_listen_hashbucket *ilb;
 521         int err = 0;
 522
 523         if (sk->sk_state != TCP_LISTEN) {
 524                 inet_ehash_nolisten(sk, osk, NULL);
 525                 return 0;
 526         }
 527         WARN_ON(!sk_unhashed(sk));
 528         ilb = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)];
 529
 530         spin_lock(&ilb->lock);
 531         if (sk->sk_reuseport) {
 532                 err = inet_reuseport_add_sock(sk, ilb);
 533                 if (err)
 534                         goto unlock;
 535         }
 536         if (IS_ENABLED(CONFIG_IPV6) && sk->sk_reuseport &&
 537                 sk->sk_family == AF_INET6)
 538                 __sk_nulls_add_node_tail_rcu(sk, &ilb->nulls_head);
 539         else
 540                 __sk_nulls_add_node_rcu(sk, &ilb->nulls_head);
 541         sock_set_flag(sk, SOCK_RCU_FREE);
 542         sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
 543 unlock:
 544         spin_unlock(&ilb->lock);
 545
 546         return err;
 547 }
 548 EXPORT_SYMBOL(__inet_hash);
 549
 550 int inet_hash(struct sock *sk)
 551 {
 552         int err = 0;
 553
 554         if (sk->sk_state != TCP_CLOSE) {
 555                 local_bh_disable();
 556                 err = __inet_hash(sk, NULL);
 557                 local_bh_enable();
 558         }
 559
 560         return err;
 561 }
 562 EXPORT_SYMBOL_GPL(inet_hash);
 563
 564 void inet_unhash(struct sock *sk)
 565 {
 566         struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
 567         spinlock_t *lock;
 568         bool listener = false;
 569         int done;
 570
 571         if (sk_unhashed(sk))
 572                 return;
 573
 574         if (sk->sk_state == TCP_LISTEN) {
 575                 lock = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)].lock;
 576                 listener = true;
 577         } else {
 578                 lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
 579         }
 580         spin_lock_bh(lock);
 581         if (rcu_access_pointer(sk->sk_reuseport_cb))
 582                 reuseport_detach_sock(sk);
 583         done = __sk_nulls_del_node_init_rcu(sk);
 584         if (done)
 585                 sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
 586         spin_unlock_bh(lock);
 587 }
 588 EXPORT_SYMBOL_GPL(inet_unhash);
 589
 590 /* RFC 6056 3.3.4.  Algorithm 4: Double-Hash Port Selection Algorithm
 591  * Note that we use 32bit integers (vs RFC 'short integers')
 592  * because 2^16 is not a multiple of num_ephemeral and this
 593  * property might be used by clever attacker.
 594  *
 595  * RFC claims using TABLE_LENGTH=10 buckets gives an improvement, though
 596  * attacks were since demonstrated, thus we use 65536 by default instead
 597  * to really give more isolation and privacy, at the expense of 256kB
 598  * of kernel memory.
 599  */
 600 #define INET_TABLE_PERTURB_SIZE (1 << CONFIG_INET_TABLE_PERTURB_ORDER)
 601 static u32 *table_perturb;
 602
 603 int __inet_hash_connect(struct inet_timewait_death_row *death_row,
 604                 struct sock *sk, u64 port_offset,
 605                 int (*check_established)(struct inet_timewait_death_row *,
 606                         struct sock *, __u16, struct inet_timewait_sock **))
 607 {
 608         struct inet_hashinfo *hinfo = death_row->hashinfo;
 609         struct inet_timewait_sock *tw = NULL;
 610         struct inet_bind_hashbucket *head;
 611         int port = inet_sk(sk)->inet_num;
 612         struct net *net = sock_net(sk);
 613         struct inet_bind_bucket *tb;
 614         u32 remaining, offset;
 615         int ret, i, low, high;
 616         u32 index;
 617
 618         if (port) {
 619                 local_bh_disable();
 620                 ret = check_established(death_row, sk, port, NULL);
 621                 local_bh_enable();
 622                 return ret;
 623         }
 624
 625         inet_get_local_port_range(net, &low, &high);
 626         high++; /* [32768, 60999] -> [32768, 61000[ */
 627         remaining = high - low;
 628         if (likely(remaining > 1))
 629                 remaining &= ~1U;
 630
 631         get_random_slow_once(table_perturb,
 632                              INET_TABLE_PERTURB_SIZE * sizeof(*table_perturb));
 633         index = port_offset & (INET_TABLE_PERTURB_SIZE - 1);
 634
 635         offset = READ_ONCE(table_perturb[index]) + (port_offset >> 32);
 636         offset %= remaining;
 637
 638         /* In first pass we try ports of @low parity.
 639          * inet_csk_get_port() does the opposite choice.
 640          */
 641         offset &= ~1U;
 642 other_parity_scan:
 643         port = low + offset;
 644         for (i = 0; i < remaining; i += 2, port += 2) {
 645                 if (unlikely(port >= high))
 646                         port -= remaining;
 647                 if (inet_is_local_reserved_port(net, port))
 648                         continue;
 649                 head = &hinfo->bhash[inet_bhashfn(net, port,
 650                                                   hinfo->bhash_size)];
 651                 spin_lock_bh(&head->lock);
 652
 653                 /* Does not bother with rcv_saddr checks, because
 654                  * the established check is already unique enough.
 655                  */
 656                 inet_bind_bucket_for_each(tb, &head->chain) {
 657                         if (net_eq(ib_net(tb), net) && tb->port == port) {
 658                                 if (tb->fastreuse >= 0 ||
 659                                     tb->fastreuseport >= 0)
 660                                         goto next_port;
 661                                 WARN_ON(hlist_empty(&tb->owners));
 662                                 if (!check_established(death_row, sk,
 663                                                        port, &tw))
 664                                         goto ok;
 665                                 goto next_port;
 666                         }
 667                 }
 668
 669                 tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep,
 670                                              net, head, port);
 671                 if (!tb) {
 672                         spin_unlock_bh(&head->lock);
 673                         return -ENOMEM;
 674                 }
 675                 tb->fastreuse = -1;
 676                 tb->fastreuseport = -1;
 677                 goto ok;
 678 next_port:
 679                 spin_unlock_bh(&head->lock);
 680                 cond_resched();
 681         }
 682
 683         offset++;
 684         if ((offset & 1) && remaining > 1)
 685                 goto other_parity_scan;
 686
 687         return -EADDRNOTAVAIL;
 688
 689 ok:
 690         /* Here we want to add a little bit of randomness to the next source
 691          * port that will be chosen. We use a max() with a random here so that
 692          * on low contention the randomness is maximal and on high contention
 693          * it may be inexistent.
 694          */
 695         i = max_t(int, i, (prandom_u32() & 7) * 2);
 696         WRITE_ONCE(table_perturb[index], READ_ONCE(table_perturb[index]) + i + 2);
 697
 698         /* Head lock still held and bh's disabled */
 699         inet_bind_hash(sk, tb, port);
 700         if (sk_unhashed(sk)) {
 701                 inet_sk(sk)->inet_sport = htons(port);
 702                 inet_ehash_nolisten(sk, (struct sock *)tw, NULL);
 703         }
 704         if (tw)
 705                 inet_twsk_bind_unhash(tw, hinfo);
 706         spin_unlock(&head->lock);
 707         if (tw)
 708                 inet_twsk_deschedule_put(tw);
 709         local_bh_enable();
 710         return 0;
 711 }
 712
 713 /*
 714  * Bind a port for a connect operation and hash it.
 715  */
 716 int inet_hash_connect(struct inet_timewait_death_row *death_row,
 717                       struct sock *sk)
 718 {
 719         u64 port_offset = 0;
 720
 721         if (!inet_sk(sk)->inet_num)
 722                 port_offset = inet_sk_port_offset(sk);
 723         return __inet_hash_connect(death_row, sk, port_offset,
 724                                    __inet_check_established);
 725 }
 726 EXPORT_SYMBOL_GPL(inet_hash_connect);
 727
 728 void inet_hashinfo_init(struct inet_hashinfo *h)
 729 {
 730         int i;
 731
 732         for (i = 0; i < INET_LHTABLE_SIZE; i++) {
 733                 spin_lock_init(&h->listening_hash[i].lock);
 734                 INIT_HLIST_NULLS_HEAD(&h->listening_hash[i].nulls_head,
 735                                       i + LISTENING_NULLS_BASE);
 736         }
 737
 738         if (h != &tcp_hashinfo)
 739                 return;
 740
 741         /* this one is used for source ports of outgoing connections */
 742         table_perturb = kmalloc_array(INET_TABLE_PERTURB_SIZE,
 743                                       sizeof(*table_perturb), GFP_KERNEL);
 744         if (!table_perturb)
 745                 panic("TCP: failed to alloc table_perturb");
 746 }
 747 EXPORT_SYMBOL_GPL(inet_hashinfo_init);
 748
 749 int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo)
 750 {
 751         unsigned int locksz = sizeof(spinlock_t);
 752         unsigned int i, nblocks = 1;
 753
 754         if (locksz != 0) {
 755                 /* allocate 2 cache lines or at least one spinlock per cpu */
 756                 nblocks = max(2U * L1_CACHE_BYTES / locksz, 1U);
 757                 nblocks = roundup_pow_of_two(nblocks * num_possible_cpus());
 758
 759                 /* no more locks than number of hash buckets */
 760                 nblocks = min(nblocks, hashinfo->ehash_mask + 1);
 761
 762                 hashinfo->ehash_locks = kvmalloc_array(nblocks, locksz, GFP_KERNEL);
 763                 if (!hashinfo->ehash_locks)
 764                         return -ENOMEM;
 765
 766                 for (i = 0; i < nblocks; i++)
 767                         spin_lock_init(&hashinfo->ehash_locks[i]);
 768         }
 769         hashinfo->ehash_locks_mask = nblocks - 1;
 770         return 0;
 771 }
 772 EXPORT_SYMBOL_GPL(inet_ehash_locks_alloc);