net/ipv4/inet_connection_sock.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   4  *              operating system.  INET is implemented using the  BSD Socket
   5  *              interface as the means of communication with the user level.
   6  *
   7  *              Support for INET connection oriented protocols.
   8  *
   9  * Authors:     See the TCP sources
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/jhash.h>
  14
  15 #include <net/inet_connection_sock.h>
  16 #include <net/inet_hashtables.h>
  17 #include <net/inet_timewait_sock.h>
  18 #include <net/ip.h>
  19 #include <net/route.h>
  20 #include <net/tcp_states.h>
  21 #include <net/xfrm.h>
  22 #include <net/tcp.h>
  23 #include <net/sock_reuseport.h>
  24 #include <net/addrconf.h>
  25
  26 #if IS_ENABLED(CONFIG_IPV6)
  27 /* match_sk*_wildcard == true:  IPV6_ADDR_ANY equals to any IPv6 addresses
  28  *                              if IPv6 only, and any IPv4 addresses
  29  *                              if not IPv6 only
  30  * match_sk*_wildcard == false: addresses must be exactly the same, i.e.
  31  *                              IPV6_ADDR_ANY only equals to IPV6_ADDR_ANY,
  32  *                              and 0.0.0.0 equals to 0.0.0.0 only
  33  */
  34 static bool ipv6_rcv_saddr_equal(const struct in6_addr *sk1_rcv_saddr6,
  35                                  const struct in6_addr *sk2_rcv_saddr6,
  36                                  __be32 sk1_rcv_saddr, __be32 sk2_rcv_saddr,
  37                                  bool sk1_ipv6only, bool sk2_ipv6only,
  38                                  bool match_sk1_wildcard,
  39                                  bool match_sk2_wildcard)
  40 {
  41         int addr_type = ipv6_addr_type(sk1_rcv_saddr6);
  42         int addr_type2 = sk2_rcv_saddr6 ? ipv6_addr_type(sk2_rcv_saddr6) : IPV6_ADDR_MAPPED;
  43
  44         /* if both are mapped, treat as IPv4 */
  45         if (addr_type == IPV6_ADDR_MAPPED && addr_type2 == IPV6_ADDR_MAPPED) {
  46                 if (!sk2_ipv6only) {
  47                         if (sk1_rcv_saddr == sk2_rcv_saddr)
  48                                 return true;
  49                         return (match_sk1_wildcard && !sk1_rcv_saddr) ||
  50                                 (match_sk2_wildcard && !sk2_rcv_saddr);
  51                 }
  52                 return false;
  53         }
  54
  55         if (addr_type == IPV6_ADDR_ANY && addr_type2 == IPV6_ADDR_ANY)
  56                 return true;
  57
  58         if (addr_type2 == IPV6_ADDR_ANY && match_sk2_wildcard &&
  59             !(sk2_ipv6only && addr_type == IPV6_ADDR_MAPPED))
  60                 return true;
  61
  62         if (addr_type == IPV6_ADDR_ANY && match_sk1_wildcard &&
  63             !(sk1_ipv6only && addr_type2 == IPV6_ADDR_MAPPED))
  64                 return true;
  65
  66         if (sk2_rcv_saddr6 &&
  67             ipv6_addr_equal(sk1_rcv_saddr6, sk2_rcv_saddr6))
  68                 return true;
  69
  70         return false;
  71 }
  72 #endif
  73
  74 /* match_sk*_wildcard == true:  0.0.0.0 equals to any IPv4 addresses
  75  * match_sk*_wildcard == false: addresses must be exactly the same, i.e.
  76  *                              0.0.0.0 only equals to 0.0.0.0
  77  */
  78 static bool ipv4_rcv_saddr_equal(__be32 sk1_rcv_saddr, __be32 sk2_rcv_saddr,
  79                                  bool sk2_ipv6only, bool match_sk1_wildcard,
  80                                  bool match_sk2_wildcard)
  81 {
  82         if (!sk2_ipv6only) {
  83                 if (sk1_rcv_saddr == sk2_rcv_saddr)
  84                         return true;
  85                 return (match_sk1_wildcard && !sk1_rcv_saddr) ||
  86                         (match_sk2_wildcard && !sk2_rcv_saddr);
  87         }
  88         return false;
  89 }
  90
  91 bool inet_rcv_saddr_equal(const struct sock *sk, const struct sock *sk2,
  92                           bool match_wildcard)
  93 {
  94 #if IS_ENABLED(CONFIG_IPV6)
  95         if (sk->sk_family == AF_INET6)
  96                 return ipv6_rcv_saddr_equal(&sk->sk_v6_rcv_saddr,
  97                                             inet6_rcv_saddr(sk2),
  98                                             sk->sk_rcv_saddr,
  99                                             sk2->sk_rcv_saddr,
 100                                             ipv6_only_sock(sk),
 101                                             ipv6_only_sock(sk2),
 102                                             match_wildcard,
 103                                             match_wildcard);
 104 #endif
 105         return ipv4_rcv_saddr_equal(sk->sk_rcv_saddr, sk2->sk_rcv_saddr,
 106                                     ipv6_only_sock(sk2), match_wildcard,
 107                                     match_wildcard);
 108 }
 109 EXPORT_SYMBOL(inet_rcv_saddr_equal);
 110
 111 bool inet_rcv_saddr_any(const struct sock *sk)
 112 {
 113 #if IS_ENABLED(CONFIG_IPV6)
 114         if (sk->sk_family == AF_INET6)
 115                 return ipv6_addr_any(&sk->sk_v6_rcv_saddr);
 116 #endif
 117         return !sk->sk_rcv_saddr;
 118 }
 119
 120 void inet_get_local_port_range(struct net *net, int *low, int *high)
 121 {
 122         unsigned int seq;
 123
 124         do {
 125                 seq = read_seqbegin(&net->ipv4.ip_local_ports.lock);
 126
 127                 *low = net->ipv4.ip_local_ports.range[0];
 128                 *high = net->ipv4.ip_local_ports.range[1];
 129         } while (read_seqretry(&net->ipv4.ip_local_ports.lock, seq));
 130 }
 131 EXPORT_SYMBOL(inet_get_local_port_range);
 132
 133 static int inet_csk_bind_conflict(const struct sock *sk,
 134                                   const struct inet_bind_bucket *tb,
 135                                   bool relax, bool reuseport_ok)
 136 {
 137         struct sock *sk2;
 138         bool reuseport_cb_ok;
 139         bool reuse = sk->sk_reuse;
 140         bool reuseport = !!sk->sk_reuseport;
 141         struct sock_reuseport *reuseport_cb;
 142         kuid_t uid = sock_i_uid((struct sock *)sk);
 143
 144         rcu_read_lock();
 145         reuseport_cb = rcu_dereference(sk->sk_reuseport_cb);
 146         /* paired with WRITE_ONCE() in __reuseport_(add|detach)_closed_sock */
 147         reuseport_cb_ok = !reuseport_cb || READ_ONCE(reuseport_cb->num_closed_socks);
 148         rcu_read_unlock();
 149
 150         /*
 151          * Unlike other sk lookup places we do not check
 152          * for sk_net here, since _all_ the socks listed
 153          * in tb->owners list belong to the same net - the
 154          * one this bucket belongs to.
 155          */
 156
 157         sk_for_each_bound(sk2, &tb->owners) {
 158                 if (sk != sk2 &&
 159                     (!sk->sk_bound_dev_if ||
 160                      !sk2->sk_bound_dev_if ||
 161                      sk->sk_bound_dev_if == sk2->sk_bound_dev_if)) {
 162                         if (reuse && sk2->sk_reuse &&
 163                             sk2->sk_state != TCP_LISTEN) {
 164                                 if ((!relax ||
 165                                      (!reuseport_ok &&
 166                                       reuseport && sk2->sk_reuseport &&
 167                                       reuseport_cb_ok &&
 168                                       (sk2->sk_state == TCP_TIME_WAIT ||
 169                                        uid_eq(uid, sock_i_uid(sk2))))) &&
 170                                     inet_rcv_saddr_equal(sk, sk2, true))
 171                                         break;
 172                         } else if (!reuseport_ok ||
 173                                    !reuseport || !sk2->sk_reuseport ||
 174                                    !reuseport_cb_ok ||
 175                                    (sk2->sk_state != TCP_TIME_WAIT &&
 176                                     !uid_eq(uid, sock_i_uid(sk2)))) {
 177                                 if (inet_rcv_saddr_equal(sk, sk2, true))
 178                                         break;
 179                         }
 180                 }
 181         }
 182         return sk2 != NULL;
 183 }
 184
 185 /*
 186  * Find an open port number for the socket.  Returns with the
 187  * inet_bind_hashbucket lock held.
 188  */
 189 static struct inet_bind_hashbucket *
 190 inet_csk_find_open_port(struct sock *sk, struct inet_bind_bucket **tb_ret, int *port_ret)
 191 {
 192         struct inet_hashinfo *hinfo = sk->sk_prot->h.hashinfo;
 193         int port = 0;
 194         struct inet_bind_hashbucket *head;
 195         struct net *net = sock_net(sk);
 196         bool relax = false;
 197         int i, low, high, attempt_half;
 198         struct inet_bind_bucket *tb;
 199         u32 remaining, offset;
 200         int l3mdev;
 201
 202         l3mdev = inet_sk_bound_l3mdev(sk);
 203 ports_exhausted:
 204         attempt_half = (sk->sk_reuse == SK_CAN_REUSE) ? 1 : 0;
 205 other_half_scan:
 206         inet_get_local_port_range(net, &low, &high);
 207         high++; /* [32768, 60999] -> [32768, 61000[ */
 208         if (high - low < 4)
 209                 attempt_half = 0;
 210         if (attempt_half) {
 211                 int half = low + (((high - low) >> 2) << 1);
 212
 213                 if (attempt_half == 1)
 214                         high = half;
 215                 else
 216                         low = half;
 217         }
 218         remaining = high - low;
 219         if (likely(remaining > 1))
 220                 remaining &= ~1U;
 221
 222         offset = prandom_u32() % remaining;
 223         /* __inet_hash_connect() favors ports having @low parity
 224          * We do the opposite to not pollute connect() users.
 225          */
 226         offset |= 1U;
 227
 228 other_parity_scan:
 229         port = low + offset;
 230         for (i = 0; i < remaining; i += 2, port += 2) {
 231                 if (unlikely(port >= high))
 232                         port -= remaining;
 233                 if (inet_is_local_reserved_port(net, port))
 234                         continue;
 235                 head = &hinfo->bhash[inet_bhashfn(net, port,
 236                                                   hinfo->bhash_size)];
 237                 spin_lock_bh(&head->lock);
 238                 inet_bind_bucket_for_each(tb, &head->chain)
 239                         if (net_eq(ib_net(tb), net) && tb->l3mdev == l3mdev &&
 240                             tb->port == port) {
 241                                 if (!inet_csk_bind_conflict(sk, tb, relax, false))
 242                                         goto success;
 243                                 goto next_port;
 244                         }
 245                 tb = NULL;
 246                 goto success;
 247 next_port:
 248                 spin_unlock_bh(&head->lock);
 249                 cond_resched();
 250         }
 251
 252         offset--;
 253         if (!(offset & 1))
 254                 goto other_parity_scan;
 255
 256         if (attempt_half == 1) {
 257                 /* OK we now try the upper half of the range */
 258                 attempt_half = 2;
 259                 goto other_half_scan;
 260         }
 261
 262         if (net->ipv4.sysctl_ip_autobind_reuse && !relax) {
 263                 /* We still have a chance to connect to different destinations */
 264                 relax = true;
 265                 goto ports_exhausted;
 266         }
 267         return NULL;
 268 success:
 269         *port_ret = port;
 270         *tb_ret = tb;
 271         return head;
 272 }
 273
 274 static inline int sk_reuseport_match(struct inet_bind_bucket *tb,
 275                                      struct sock *sk)
 276 {
 277         kuid_t uid = sock_i_uid(sk);
 278
 279         if (tb->fastreuseport <= 0)
 280                 return 0;
 281         if (!sk->sk_reuseport)
 282                 return 0;
 283         if (rcu_access_pointer(sk->sk_reuseport_cb))
 284                 return 0;
 285         if (!uid_eq(tb->fastuid, uid))
 286                 return 0;
 287         /* We only need to check the rcv_saddr if this tb was once marked
 288          * without fastreuseport and then was reset, as we can only know that
 289          * the fast_*rcv_saddr doesn't have any conflicts with the socks on the
 290          * owners list.
 291          */
 292         if (tb->fastreuseport == FASTREUSEPORT_ANY)
 293                 return 1;
 294 #if IS_ENABLED(CONFIG_IPV6)
 295         if (tb->fast_sk_family == AF_INET6)
 296                 return ipv6_rcv_saddr_equal(&tb->fast_v6_rcv_saddr,
 297                                             inet6_rcv_saddr(sk),
 298                                             tb->fast_rcv_saddr,
 299                                             sk->sk_rcv_saddr,
 300                                             tb->fast_ipv6_only,
 301                                             ipv6_only_sock(sk), true, false);
 302 #endif
 303         return ipv4_rcv_saddr_equal(tb->fast_rcv_saddr, sk->sk_rcv_saddr,
 304                                     ipv6_only_sock(sk), true, false);
 305 }
 306
 307 void inet_csk_update_fastreuse(struct inet_bind_bucket *tb,
 308                                struct sock *sk)
 309 {
 310         kuid_t uid = sock_i_uid(sk);
 311         bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN;
 312
 313         if (hlist_empty(&tb->owners)) {
 314                 tb->fastreuse = reuse;
 315                 if (sk->sk_reuseport) {
 316                         tb->fastreuseport = FASTREUSEPORT_ANY;
 317                         tb->fastuid = uid;
 318                         tb->fast_rcv_saddr = sk->sk_rcv_saddr;
 319                         tb->fast_ipv6_only = ipv6_only_sock(sk);
 320                         tb->fast_sk_family = sk->sk_family;
 321 #if IS_ENABLED(CONFIG_IPV6)
 322                         tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
 323 #endif
 324                 } else {
 325                         tb->fastreuseport = 0;
 326                 }
 327         } else {
 328                 if (!reuse)
 329                         tb->fastreuse = 0;
 330                 if (sk->sk_reuseport) {
 331                         /* We didn't match or we don't have fastreuseport set on
 332                          * the tb, but we have sk_reuseport set on this socket
 333                          * and we know that there are no bind conflicts with
 334                          * this socket in this tb, so reset our tb's reuseport
 335                          * settings so that any subsequent sockets that match
 336                          * our current socket will be put on the fast path.
 337                          *
 338                          * If we reset we need to set FASTREUSEPORT_STRICT so we
 339                          * do extra checking for all subsequent sk_reuseport
 340                          * socks.
 341                          */
 342                         if (!sk_reuseport_match(tb, sk)) {
 343                                 tb->fastreuseport = FASTREUSEPORT_STRICT;
 344                                 tb->fastuid = uid;
 345                                 tb->fast_rcv_saddr = sk->sk_rcv_saddr;
 346                                 tb->fast_ipv6_only = ipv6_only_sock(sk);
 347                                 tb->fast_sk_family = sk->sk_family;
 348 #if IS_ENABLED(CONFIG_IPV6)
 349                                 tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
 350 #endif
 351                         }
 352                 } else {
 353                         tb->fastreuseport = 0;
 354                 }
 355         }
 356 }
 357
 358 /* Obtain a reference to a local port for the given sock,
 359  * if snum is zero it means select any available local port.
 360  * We try to allocate an odd port (and leave even ports for connect())
 361  */
 362 int inet_csk_get_port(struct sock *sk, unsigned short snum)
 363 {
 364         bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN;
 365         struct inet_hashinfo *hinfo = sk->sk_prot->h.hashinfo;
 366         int ret = 1, port = snum;
 367         struct inet_bind_hashbucket *head;
 368         struct net *net = sock_net(sk);
 369         struct inet_bind_bucket *tb = NULL;
 370         int l3mdev;
 371
 372         l3mdev = inet_sk_bound_l3mdev(sk);
 373
 374         if (!port) {
 375                 head = inet_csk_find_open_port(sk, &tb, &port);
 376                 if (!head)
 377                         return ret;
 378                 if (!tb)
 379                         goto tb_not_found;
 380                 goto success;
 381         }
 382         head = &hinfo->bhash[inet_bhashfn(net, port,
 383                                           hinfo->bhash_size)];
 384         spin_lock_bh(&head->lock);
 385         inet_bind_bucket_for_each(tb, &head->chain)
 386                 if (net_eq(ib_net(tb), net) && tb->l3mdev == l3mdev &&
 387                     tb->port == port)
 388                         goto tb_found;
 389 tb_not_found:
 390         tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep,
 391                                      net, head, port, l3mdev);
 392         if (!tb)
 393                 goto fail_unlock;
 394 tb_found:
 395         if (!hlist_empty(&tb->owners)) {
 396                 if (sk->sk_reuse == SK_FORCE_REUSE)
 397                         goto success;
 398
 399                 if ((tb->fastreuse > 0 && reuse) ||
 400                     sk_reuseport_match(tb, sk))
 401                         goto success;
 402                 if (inet_csk_bind_conflict(sk, tb, true, true))
 403                         goto fail_unlock;
 404         }
 405 success:
 406         inet_csk_update_fastreuse(tb, sk);
 407
 408         if (!inet_csk(sk)->icsk_bind_hash)
 409                 inet_bind_hash(sk, tb, port);
 410         WARN_ON(inet_csk(sk)->icsk_bind_hash != tb);
 411         ret = 0;
 412
 413 fail_unlock:
 414         spin_unlock_bh(&head->lock);
 415         return ret;
 416 }
 417 EXPORT_SYMBOL_GPL(inet_csk_get_port);
 418
 419 /*
 420  * Wait for an incoming connection, avoid race conditions. This must be called
 421  * with the socket locked.
 422  */
 423 static int inet_csk_wait_for_connect(struct sock *sk, long timeo)
 424 {
 425         struct inet_connection_sock *icsk = inet_csk(sk);
 426         DEFINE_WAIT(wait);
 427         int err;
 428
 429         /*
 430          * True wake-one mechanism for incoming connections: only
 431          * one process gets woken up, not the 'whole herd'.
 432          * Since we do not 'race & poll' for established sockets
 433          * anymore, the common case will execute the loop only once.
 434          *
 435          * Subtle issue: "add_wait_queue_exclusive()" will be added
 436          * after any current non-exclusive waiters, and we know that
 437          * it will always _stay_ after any new non-exclusive waiters
 438          * because all non-exclusive waiters are added at the
 439          * beginning of the wait-queue. As such, it's ok to "drop"
 440          * our exclusiveness temporarily when we get woken up without
 441          * having to remove and re-insert us on the wait queue.
 442          */
 443         for (;;) {
 444                 prepare_to_wait_exclusive(sk_sleep(sk), &wait,
 445                                           TASK_INTERRUPTIBLE);
 446                 release_sock(sk);
 447                 if (reqsk_queue_empty(&icsk->icsk_accept_queue))
 448                         timeo = schedule_timeout(timeo);
 449                 sched_annotate_sleep();
 450                 lock_sock(sk);
 451                 err = 0;
 452                 if (!reqsk_queue_empty(&icsk->icsk_accept_queue))
 453                         break;
 454                 err = -EINVAL;
 455                 if (sk->sk_state != TCP_LISTEN)
 456                         break;
 457                 err = sock_intr_errno(timeo);
 458                 if (signal_pending(current))
 459                         break;
 460                 err = -EAGAIN;
 461                 if (!timeo)
 462                         break;
 463         }
 464         finish_wait(sk_sleep(sk), &wait);
 465         return err;
 466 }
 467
 468 /*
 469  * This will accept the next outstanding connection.
 470  */
 471 struct sock *inet_csk_accept(struct sock *sk, int flags, int *err, bool kern)
 472 {
 473         struct inet_connection_sock *icsk = inet_csk(sk);
 474         struct request_sock_queue *queue = &icsk->icsk_accept_queue;
 475         struct request_sock *req;
 476         struct sock *newsk;
 477         int error;
 478
 479         lock_sock(sk);
 480
 481         /* We need to make sure that this socket is listening,
 482          * and that it has something pending.
 483          */
 484         error = -EINVAL;
 485         if (sk->sk_state != TCP_LISTEN)
 486                 goto out_err;
 487
 488         /* Find already established connection */
 489         if (reqsk_queue_empty(queue)) {
 490                 long timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);
 491
 492                 /* If this is a non blocking socket don't sleep */
 493                 error = -EAGAIN;
 494                 if (!timeo)
 495                         goto out_err;
 496
 497                 error = inet_csk_wait_for_connect(sk, timeo);
 498                 if (error)
 499                         goto out_err;
 500         }
 501         req = reqsk_queue_remove(queue, sk);
 502         newsk = req->sk;
 503
 504         if (sk->sk_protocol == IPPROTO_TCP &&
 505             tcp_rsk(req)->tfo_listener) {
 506                 spin_lock_bh(&queue->fastopenq.lock);
 507                 if (tcp_rsk(req)->tfo_listener) {
 508                         /* We are still waiting for the final ACK from 3WHS
 509                          * so can't free req now. Instead, we set req->sk to
 510                          * NULL to signify that the child socket is taken
 511                          * so reqsk_fastopen_remove() will free the req
 512                          * when 3WHS finishes (or is aborted).
 513                          */
 514                         req->sk = NULL;
 515                         req = NULL;
 516                 }
 517                 spin_unlock_bh(&queue->fastopenq.lock);
 518         }
 519
 520 out:
 521         release_sock(sk);
 522         if (newsk && mem_cgroup_sockets_enabled) {
 523                 int amt;
 524
 525                 /* atomically get the memory usage, set and charge the
 526                  * newsk->sk_memcg.
 527                  */
 528                 lock_sock(newsk);
 529
 530                 /* The socket has not been accepted yet, no need to look at
 531                  * newsk->sk_wmem_queued.
 532                  */
 533                 amt = sk_mem_pages(newsk->sk_forward_alloc +
 534                                    atomic_read(&newsk->sk_rmem_alloc));
 535                 mem_cgroup_sk_alloc(newsk);
 536                 if (newsk->sk_memcg && amt)
 537                         mem_cgroup_charge_skmem(newsk->sk_memcg, amt,
 538                                                 GFP_KERNEL | __GFP_NOFAIL);
 539
 540                 release_sock(newsk);
 541         }
 542         if (req)
 543                 reqsk_put(req);
 544         return newsk;
 545 out_err:
 546         newsk = NULL;
 547         req = NULL;
 548         *err = error;
 549         goto out;
 550 }
 551 EXPORT_SYMBOL(inet_csk_accept);
 552
 553 /*
 554  * Using different timers for retransmit, delayed acks and probes
 555  * We may wish use just one timer maintaining a list of expire jiffies
 556  * to optimize.
 557  */
 558 void inet_csk_init_xmit_timers(struct sock *sk,
 559                                void (*retransmit_handler)(struct timer_list *t),
 560                                void (*delack_handler)(struct timer_list *t),
 561                                void (*keepalive_handler)(struct timer_list *t))
 562 {
 563         struct inet_connection_sock *icsk = inet_csk(sk);
 564
 565         timer_setup(&icsk->icsk_retransmit_timer, retransmit_handler, 0);
 566         timer_setup(&icsk->icsk_delack_timer, delack_handler, 0);
 567         timer_setup(&sk->sk_timer, keepalive_handler, 0);
 568         icsk->icsk_pending = icsk->icsk_ack.pending = 0;
 569 }
 570 EXPORT_SYMBOL(inet_csk_init_xmit_timers);
 571
 572 void inet_csk_clear_xmit_timers(struct sock *sk)
 573 {
 574         struct inet_connection_sock *icsk = inet_csk(sk);
 575
 576         icsk->icsk_pending = icsk->icsk_ack.pending = 0;
 577
 578         sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
 579         sk_stop_timer(sk, &icsk->icsk_delack_timer);
 580         sk_stop_timer(sk, &sk->sk_timer);
 581 }
 582 EXPORT_SYMBOL(inet_csk_clear_xmit_timers);
 583
 584 void inet_csk_delete_keepalive_timer(struct sock *sk)
 585 {
 586         sk_stop_timer(sk, &sk->sk_timer);
 587 }
 588 EXPORT_SYMBOL(inet_csk_delete_keepalive_timer);
 589
 590 void inet_csk_reset_keepalive_timer(struct sock *sk, unsigned long len)
 591 {
 592         sk_reset_timer(sk, &sk->sk_timer, jiffies + len);
 593 }
 594 EXPORT_SYMBOL(inet_csk_reset_keepalive_timer);
 595
 596 struct dst_entry *inet_csk_route_req(const struct sock *sk,
 597                                      struct flowi4 *fl4,
 598                                      const struct request_sock *req)
 599 {
 600         const struct inet_request_sock *ireq = inet_rsk(req);
 601         struct net *net = read_pnet(&ireq->ireq_net);
 602         struct ip_options_rcu *opt;
 603         struct rtable *rt;
 604
 605         rcu_read_lock();
 606         opt = rcu_dereference(ireq->ireq_opt);
 607
 608         flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
 609                            RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
 610                            sk->sk_protocol, inet_sk_flowi_flags(sk),
 611                            (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
 612                            ireq->ir_loc_addr, ireq->ir_rmt_port,
 613                            htons(ireq->ir_num), sk->sk_uid);
 614         security_req_classify_flow(req, flowi4_to_flowi_common(fl4));
 615         rt = ip_route_output_flow(net, fl4, sk);
 616         if (IS_ERR(rt))
 617                 goto no_route;
 618         if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
 619                 goto route_err;
 620         rcu_read_unlock();
 621         return &rt->dst;
 622
 623 route_err:
 624         ip_rt_put(rt);
 625 no_route:
 626         rcu_read_unlock();
 627         __IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
 628         return NULL;
 629 }
 630 EXPORT_SYMBOL_GPL(inet_csk_route_req);
 631
 632 struct dst_entry *inet_csk_route_child_sock(const struct sock *sk,
 633                                             struct sock *newsk,
 634                                             const struct request_sock *req)
 635 {
 636         const struct inet_request_sock *ireq = inet_rsk(req);
 637         struct net *net = read_pnet(&ireq->ireq_net);
 638         struct inet_sock *newinet = inet_sk(newsk);
 639         struct ip_options_rcu *opt;
 640         struct flowi4 *fl4;
 641         struct rtable *rt;
 642
 643         opt = rcu_dereference(ireq->ireq_opt);
 644         fl4 = &newinet->cork.fl.u.ip4;
 645
 646         flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
 647                            RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
 648                            sk->sk_protocol, inet_sk_flowi_flags(sk),
 649                            (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
 650                            ireq->ir_loc_addr, ireq->ir_rmt_port,
 651                            htons(ireq->ir_num), sk->sk_uid);
 652         security_req_classify_flow(req, flowi4_to_flowi_common(fl4));
 653         rt = ip_route_output_flow(net, fl4, sk);
 654         if (IS_ERR(rt))
 655                 goto no_route;
 656         if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
 657                 goto route_err;
 658         return &rt->dst;
 659
 660 route_err:
 661         ip_rt_put(rt);
 662 no_route:
 663         __IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
 664         return NULL;
 665 }
 666 EXPORT_SYMBOL_GPL(inet_csk_route_child_sock);
 667
 668 /* Decide when to expire the request and when to resend SYN-ACK */
 669 static void syn_ack_recalc(struct request_sock *req,
 670                            const int max_syn_ack_retries,
 671                            const u8 rskq_defer_accept,
 672                            int *expire, int *resend)
 673 {
 674         if (!rskq_defer_accept) {
 675                 *expire = req->num_timeout >= max_syn_ack_retries;
 676                 *resend = 1;
 677                 return;
 678         }
 679         *expire = req->num_timeout >= max_syn_ack_retries &&
 680                   (!inet_rsk(req)->acked || req->num_timeout >= rskq_defer_accept);
 681         /* Do not resend while waiting for data after ACK,
 682          * start to resend on end of deferring period to give
 683          * last chance for data or ACK to create established socket.
 684          */
 685         *resend = !inet_rsk(req)->acked ||
 686                   req->num_timeout >= rskq_defer_accept - 1;
 687 }
 688
 689 int inet_rtx_syn_ack(const struct sock *parent, struct request_sock *req)
 690 {
 691         int err = req->rsk_ops->rtx_syn_ack(parent, req);
 692
 693         if (!err)
 694                 req->num_retrans++;
 695         return err;
 696 }
 697 EXPORT_SYMBOL(inet_rtx_syn_ack);
 698
 699 static struct request_sock *inet_reqsk_clone(struct request_sock *req,
 700                                              struct sock *sk)
 701 {
 702         struct sock *req_sk, *nreq_sk;
 703         struct request_sock *nreq;
 704
 705         nreq = kmem_cache_alloc(req->rsk_ops->slab, GFP_ATOMIC | __GFP_NOWARN);
 706         if (!nreq) {
 707                 __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQFAILURE);
 708
 709                 /* paired with refcount_inc_not_zero() in reuseport_migrate_sock() */
 710                 sock_put(sk);
 711                 return NULL;
 712         }
 713
 714         req_sk = req_to_sk(req);
 715         nreq_sk = req_to_sk(nreq);
 716
 717         memcpy(nreq_sk, req_sk,
 718                offsetof(struct sock, sk_dontcopy_begin));
 719         memcpy(&nreq_sk->sk_dontcopy_end, &req_sk->sk_dontcopy_end,
 720                req->rsk_ops->obj_size - offsetof(struct sock, sk_dontcopy_end));
 721
 722         sk_node_init(&nreq_sk->sk_node);
 723         nreq_sk->sk_tx_queue_mapping = req_sk->sk_tx_queue_mapping;
 724 #ifdef CONFIG_XPS
 725         nreq_sk->sk_rx_queue_mapping = req_sk->sk_rx_queue_mapping;
 726 #endif
 727         nreq_sk->sk_incoming_cpu = req_sk->sk_incoming_cpu;
 728
 729         nreq->rsk_listener = sk;
 730
 731         /* We need not acquire fastopenq->lock
 732          * because the child socket is locked in inet_csk_listen_stop().
 733          */
 734         if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(nreq)->tfo_listener)
 735                 rcu_assign_pointer(tcp_sk(nreq->sk)->fastopen_rsk, nreq);
 736
 737         return nreq;
 738 }
 739
 740 static void reqsk_queue_migrated(struct request_sock_queue *queue,
 741                                  const struct request_sock *req)
 742 {
 743         if (req->num_timeout == 0)
 744                 atomic_inc(&queue->young);
 745         atomic_inc(&queue->qlen);
 746 }
 747
 748 static void reqsk_migrate_reset(struct request_sock *req)
 749 {
 750         req->saved_syn = NULL;
 751 #if IS_ENABLED(CONFIG_IPV6)
 752         inet_rsk(req)->ipv6_opt = NULL;
 753         inet_rsk(req)->pktopts = NULL;
 754 #else
 755         inet_rsk(req)->ireq_opt = NULL;
 756 #endif
 757 }
 758
 759 /* return true if req was found in the ehash table */
 760 static bool reqsk_queue_unlink(struct request_sock *req)
 761 {
 762         struct inet_hashinfo *hashinfo = req_to_sk(req)->sk_prot->h.hashinfo;
 763         bool found = false;
 764
 765         if (sk_hashed(req_to_sk(req))) {
 766                 spinlock_t *lock = inet_ehash_lockp(hashinfo, req->rsk_hash);
 767
 768                 spin_lock(lock);
 769                 found = __sk_nulls_del_node_init_rcu(req_to_sk(req));
 770                 spin_unlock(lock);
 771         }
 772         if (timer_pending(&req->rsk_timer) && del_timer_sync(&req->rsk_timer))
 773                 reqsk_put(req);
 774         return found;
 775 }
 776
 777 bool inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req)
 778 {
 779         bool unlinked = reqsk_queue_unlink(req);
 780
 781         if (unlinked) {
 782                 reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req);
 783                 reqsk_put(req);
 784         }
 785         return unlinked;
 786 }
 787 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop);
 788
 789 void inet_csk_reqsk_queue_drop_and_put(struct sock *sk, struct request_sock *req)
 790 {
 791         inet_csk_reqsk_queue_drop(sk, req);
 792         reqsk_put(req);
 793 }
 794 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop_and_put);
 795
 796 static void reqsk_timer_handler(struct timer_list *t)
 797 {
 798         struct request_sock *req = from_timer(req, t, rsk_timer);
 799         struct request_sock *nreq = NULL, *oreq = req;
 800         struct sock *sk_listener = req->rsk_listener;
 801         struct inet_connection_sock *icsk;
 802         struct request_sock_queue *queue;
 803         struct net *net;
 804         int max_syn_ack_retries, qlen, expire = 0, resend = 0;
 805
 806         if (inet_sk_state_load(sk_listener) != TCP_LISTEN) {
 807                 struct sock *nsk;
 808
 809                 nsk = reuseport_migrate_sock(sk_listener, req_to_sk(req), NULL);
 810                 if (!nsk)
 811                         goto drop;
 812
 813                 nreq = inet_reqsk_clone(req, nsk);
 814                 if (!nreq)
 815                         goto drop;
 816
 817                 /* The new timer for the cloned req can decrease the 2
 818                  * by calling inet_csk_reqsk_queue_drop_and_put(), so
 819                  * hold another count to prevent use-after-free and
 820                  * call reqsk_put() just before return.
 821                  */
 822                 refcount_set(&nreq->rsk_refcnt, 2 + 1);
 823                 timer_setup(&nreq->rsk_timer, reqsk_timer_handler, TIMER_PINNED);
 824                 reqsk_queue_migrated(&inet_csk(nsk)->icsk_accept_queue, req);
 825
 826                 req = nreq;
 827                 sk_listener = nsk;
 828         }
 829
 830         icsk = inet_csk(sk_listener);
 831         net = sock_net(sk_listener);
 832         max_syn_ack_retries = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_synack_retries;
 833         /* Normally all the openreqs are young and become mature
 834          * (i.e. converted to established socket) for first timeout.
 835          * If synack was not acknowledged for 1 second, it means
 836          * one of the following things: synack was lost, ack was lost,
 837          * rtt is high or nobody planned to ack (i.e. synflood).
 838          * When server is a bit loaded, queue is populated with old
 839          * open requests, reducing effective size of queue.
 840          * When server is well loaded, queue size reduces to zero
 841          * after several minutes of work. It is not synflood,
 842          * it is normal operation. The solution is pruning
 843          * too old entries overriding normal timeout, when
 844          * situation becomes dangerous.
 845          *
 846          * Essentially, we reserve half of room for young
 847          * embrions; and abort old ones without pity, if old
 848          * ones are about to clog our table.
 849          */
 850         queue = &icsk->icsk_accept_queue;
 851         qlen = reqsk_queue_len(queue);
 852         if ((qlen << 1) > max(8U, READ_ONCE(sk_listener->sk_max_ack_backlog))) {
 853                 int young = reqsk_queue_len_young(queue) << 1;
 854
 855                 while (max_syn_ack_retries > 2) {
 856                         if (qlen < young)
 857                                 break;
 858                         max_syn_ack_retries--;
 859                         young <<= 1;
 860                 }
 861         }
 862         syn_ack_recalc(req, max_syn_ack_retries, READ_ONCE(queue->rskq_defer_accept),
 863                        &expire, &resend);
 864         req->rsk_ops->syn_ack_timeout(req);
 865         if (!expire &&
 866             (!resend ||
 867              !inet_rtx_syn_ack(sk_listener, req) ||
 868              inet_rsk(req)->acked)) {
 869                 unsigned long timeo;
 870
 871                 if (req->num_timeout++ == 0)
 872                         atomic_dec(&queue->young);
 873                 timeo = min(TCP_TIMEOUT_INIT << req->num_timeout, TCP_RTO_MAX);
 874                 mod_timer(&req->rsk_timer, jiffies + timeo);
 875
 876                 if (!nreq)
 877                         return;
 878
 879                 if (!inet_ehash_insert(req_to_sk(nreq), req_to_sk(oreq), NULL)) {
 880                         /* delete timer */
 881                         inet_csk_reqsk_queue_drop(sk_listener, nreq);
 882                         goto no_ownership;
 883                 }
 884
 885                 __NET_INC_STATS(net, LINUX_MIB_TCPMIGRATEREQSUCCESS);
 886                 reqsk_migrate_reset(oreq);
 887                 reqsk_queue_removed(&inet_csk(oreq->rsk_listener)->icsk_accept_queue, oreq);
 888                 reqsk_put(oreq);
 889
 890                 reqsk_put(nreq);
 891                 return;
 892         }
 893
 894         /* Even if we can clone the req, we may need not retransmit any more
 895          * SYN+ACKs (nreq->num_timeout > max_syn_ack_retries, etc), or another
 896          * CPU may win the "own_req" race so that inet_ehash_insert() fails.
 897          */
 898         if (nreq) {
 899                 __NET_INC_STATS(net, LINUX_MIB_TCPMIGRATEREQFAILURE);
 900 no_ownership:
 901                 reqsk_migrate_reset(nreq);
 902                 reqsk_queue_removed(queue, nreq);
 903                 __reqsk_free(nreq);
 904         }
 905
 906 drop:
 907         inet_csk_reqsk_queue_drop_and_put(oreq->rsk_listener, oreq);
 908 }
 909
 910 static void reqsk_queue_hash_req(struct request_sock *req,
 911                                  unsigned long timeout)
 912 {
 913         timer_setup(&req->rsk_timer, reqsk_timer_handler, TIMER_PINNED);
 914         mod_timer(&req->rsk_timer, jiffies + timeout);
 915
 916         inet_ehash_insert(req_to_sk(req), NULL, NULL);
 917         /* before letting lookups find us, make sure all req fields
 918          * are committed to memory and refcnt initialized.
 919          */
 920         smp_wmb();
 921         refcount_set(&req->rsk_refcnt, 2 + 1);
 922 }
 923
 924 void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
 925                                    unsigned long timeout)
 926 {
 927         reqsk_queue_hash_req(req, timeout);
 928         inet_csk_reqsk_queue_added(sk);
 929 }
 930 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add);
 931
 932 static void inet_clone_ulp(const struct request_sock *req, struct sock *newsk,
 933                            const gfp_t priority)
 934 {
 935         struct inet_connection_sock *icsk = inet_csk(newsk);
 936
 937         if (!icsk->icsk_ulp_ops)
 938                 return;
 939
 940         if (icsk->icsk_ulp_ops->clone)
 941                 icsk->icsk_ulp_ops->clone(req, newsk, priority);
 942 }
 943
 944 /**
 945  *      inet_csk_clone_lock - clone an inet socket, and lock its clone
 946  *      @sk: the socket to clone
 947  *      @req: request_sock
 948  *      @priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc)
 949  *
 950  *      Caller must unlock socket even in error path (bh_unlock_sock(newsk))
 951  */
 952 struct sock *inet_csk_clone_lock(const struct sock *sk,
 953                                  const struct request_sock *req,
 954                                  const gfp_t priority)
 955 {
 956         struct sock *newsk = sk_clone_lock(sk, priority);
 957
 958         if (newsk) {
 959                 struct inet_connection_sock *newicsk = inet_csk(newsk);
 960
 961                 inet_sk_set_state(newsk, TCP_SYN_RECV);
 962                 newicsk->icsk_bind_hash = NULL;
 963
 964                 inet_sk(newsk)->inet_dport = inet_rsk(req)->ir_rmt_port;
 965                 inet_sk(newsk)->inet_num = inet_rsk(req)->ir_num;
 966                 inet_sk(newsk)->inet_sport = htons(inet_rsk(req)->ir_num);
 967
 968                 /* listeners have SOCK_RCU_FREE, not the children */
 969                 sock_reset_flag(newsk, SOCK_RCU_FREE);
 970
 971                 inet_sk(newsk)->mc_list = NULL;
 972
 973                 newsk->sk_mark = inet_rsk(req)->ir_mark;
 974                 atomic64_set(&newsk->sk_cookie,
 975                              atomic64_read(&inet_rsk(req)->ir_cookie));
 976
 977                 newicsk->icsk_retransmits = 0;
 978                 newicsk->icsk_backoff     = 0;
 979                 newicsk->icsk_probes_out  = 0;
 980                 newicsk->icsk_probes_tstamp = 0;
 981
 982                 /* Deinitialize accept_queue to trap illegal accesses. */
 983                 memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue));
 984
 985                 inet_clone_ulp(req, newsk, priority);
 986
 987                 security_inet_csk_clone(newsk, req);
 988         }
 989         return newsk;
 990 }
 991 EXPORT_SYMBOL_GPL(inet_csk_clone_lock);
 992
 993 /*
 994  * At this point, there should be no process reference to this
 995  * socket, and thus no user references at all.  Therefore we
 996  * can assume the socket waitqueue is inactive and nobody will
 997  * try to jump onto it.
 998  */
 999 void inet_csk_destroy_sock(struct sock *sk)
1000 {
1001         WARN_ON(sk->sk_state != TCP_CLOSE);
1002         WARN_ON(!sock_flag(sk, SOCK_DEAD));
1003
1004         /* It cannot be in hash table! */
1005         WARN_ON(!sk_unhashed(sk));
1006
1007         /* If it has not 0 inet_sk(sk)->inet_num, it must be bound */
1008         WARN_ON(inet_sk(sk)->inet_num && !inet_csk(sk)->icsk_bind_hash);
1009
1010         sk->sk_prot->destroy(sk);
1011
1012         sk_stream_kill_queues(sk);
1013
1014         xfrm_sk_free_policy(sk);
1015
1016         sk_refcnt_debug_release(sk);
1017
1018         percpu_counter_dec(sk->sk_prot->orphan_count);
1019
1020         sock_put(sk);
1021 }
1022 EXPORT_SYMBOL(inet_csk_destroy_sock);
1023
1024 /* This function allows to force a closure of a socket after the call to
1025  * tcp/dccp_create_openreq_child().
1026  */
1027 void inet_csk_prepare_forced_close(struct sock *sk)
1028         __releases(&sk->sk_lock.slock)
1029 {
1030         /* sk_clone_lock locked the socket and set refcnt to 2 */
1031         bh_unlock_sock(sk);
1032         sock_put(sk);
1033         inet_csk_prepare_for_destroy_sock(sk);
1034         inet_sk(sk)->inet_num = 0;
1035 }
1036 EXPORT_SYMBOL(inet_csk_prepare_forced_close);
1037
1038 int inet_csk_listen_start(struct sock *sk, int backlog)
1039 {
1040         struct inet_connection_sock *icsk = inet_csk(sk);
1041         struct inet_sock *inet = inet_sk(sk);
1042         int err = -EADDRINUSE;
1043
1044         reqsk_queue_alloc(&icsk->icsk_accept_queue);
1045
1046         sk->sk_ack_backlog = 0;
1047         inet_csk_delack_init(sk);
1048
1049         /* There is race window here: we announce ourselves listening,
1050          * but this transition is still not validated by get_port().
1051          * It is OK, because this socket enters to hash table only
1052          * after validation is complete.
1053          */
1054         inet_sk_state_store(sk, TCP_LISTEN);
1055         if (!sk->sk_prot->get_port(sk, inet->inet_num)) {
1056                 inet->inet_sport = htons(inet->inet_num);
1057
1058                 sk_dst_reset(sk);
1059                 err = sk->sk_prot->hash(sk);
1060
1061                 if (likely(!err))
1062                         return 0;
1063         }
1064
1065         inet_sk_set_state(sk, TCP_CLOSE);
1066         return err;
1067 }
1068 EXPORT_SYMBOL_GPL(inet_csk_listen_start);
1069
1070 static void inet_child_forget(struct sock *sk, struct request_sock *req,
1071                               struct sock *child)
1072 {
1073         sk->sk_prot->disconnect(child, O_NONBLOCK);
1074
1075         sock_orphan(child);
1076
1077         percpu_counter_inc(sk->sk_prot->orphan_count);
1078
1079         if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(req)->tfo_listener) {
1080                 BUG_ON(rcu_access_pointer(tcp_sk(child)->fastopen_rsk) != req);
1081                 BUG_ON(sk != req->rsk_listener);
1082
1083                 /* Paranoid, to prevent race condition if
1084                  * an inbound pkt destined for child is
1085                  * blocked by sock lock in tcp_v4_rcv().
1086                  * Also to satisfy an assertion in
1087                  * tcp_v4_destroy_sock().
1088                  */
1089                 RCU_INIT_POINTER(tcp_sk(child)->fastopen_rsk, NULL);
1090         }
1091         inet_csk_destroy_sock(child);
1092 }
1093
1094 struct sock *inet_csk_reqsk_queue_add(struct sock *sk,
1095                                       struct request_sock *req,
1096                                       struct sock *child)
1097 {
1098         struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
1099
1100         spin_lock(&queue->rskq_lock);
1101         if (unlikely(sk->sk_state != TCP_LISTEN)) {
1102                 inet_child_forget(sk, req, child);
1103                 child = NULL;
1104         } else {
1105                 req->sk = child;
1106                 req->dl_next = NULL;
1107                 if (queue->rskq_accept_head == NULL)
1108                         WRITE_ONCE(queue->rskq_accept_head, req);
1109                 else
1110                         queue->rskq_accept_tail->dl_next = req;
1111                 queue->rskq_accept_tail = req;
1112                 sk_acceptq_added(sk);
1113         }
1114         spin_unlock(&queue->rskq_lock);
1115         return child;
1116 }
1117 EXPORT_SYMBOL(inet_csk_reqsk_queue_add);
1118
1119 struct sock *inet_csk_complete_hashdance(struct sock *sk, struct sock *child,
1120                                          struct request_sock *req, bool own_req)
1121 {
1122         if (own_req) {
1123                 inet_csk_reqsk_queue_drop(req->rsk_listener, req);
1124                 reqsk_queue_removed(&inet_csk(req->rsk_listener)->icsk_accept_queue, req);
1125
1126                 if (sk != req->rsk_listener) {
1127                         /* another listening sk has been selected,
1128                          * migrate the req to it.
1129                          */
1130                         struct request_sock *nreq;
1131
1132                         /* hold a refcnt for the nreq->rsk_listener
1133                          * which is assigned in inet_reqsk_clone()
1134                          */
1135                         sock_hold(sk);
1136                         nreq = inet_reqsk_clone(req, sk);
1137                         if (!nreq) {
1138                                 inet_child_forget(sk, req, child);
1139                                 goto child_put;
1140                         }
1141
1142                         refcount_set(&nreq->rsk_refcnt, 1);
1143                         if (inet_csk_reqsk_queue_add(sk, nreq, child)) {
1144                                 __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQSUCCESS);
1145                                 reqsk_migrate_reset(req);
1146                                 reqsk_put(req);
1147                                 return child;
1148                         }
1149
1150                         __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQFAILURE);
1151                         reqsk_migrate_reset(nreq);
1152                         __reqsk_free(nreq);
1153                 } else if (inet_csk_reqsk_queue_add(sk, req, child)) {
1154                         return child;
1155                 }
1156         }
1157         /* Too bad, another child took ownership of the request, undo. */
1158 child_put:
1159         bh_unlock_sock(child);
1160         sock_put(child);
1161         return NULL;
1162 }
1163 EXPORT_SYMBOL(inet_csk_complete_hashdance);
1164
1165 /*
1166  *      This routine closes sockets which have been at least partially
1167  *      opened, but not yet accepted.
1168  */
1169 void inet_csk_listen_stop(struct sock *sk)
1170 {
1171         struct inet_connection_sock *icsk = inet_csk(sk);
1172         struct request_sock_queue *queue = &icsk->icsk_accept_queue;
1173         struct request_sock *next, *req;
1174
1175         /* Following specs, it would be better either to send FIN
1176          * (and enter FIN-WAIT-1, it is normal close)
1177          * or to send active reset (abort).
1178          * Certainly, it is pretty dangerous while synflood, but it is
1179          * bad justification for our negligence 8)
1180          * To be honest, we are not able to make either
1181          * of the variants now.                 --ANK
1182          */
1183         while ((req = reqsk_queue_remove(queue, sk)) != NULL) {
1184                 struct sock *child = req->sk, *nsk;
1185                 struct request_sock *nreq;
1186
1187                 local_bh_disable();
1188                 bh_lock_sock(child);
1189                 WARN_ON(sock_owned_by_user(child));
1190                 sock_hold(child);
1191
1192                 nsk = reuseport_migrate_sock(sk, child, NULL);
1193                 if (nsk) {
1194                         nreq = inet_reqsk_clone(req, nsk);
1195                         if (nreq) {
1196                                 refcount_set(&nreq->rsk_refcnt, 1);
1197
1198                                 if (inet_csk_reqsk_queue_add(nsk, nreq, child)) {
1199                                         __NET_INC_STATS(sock_net(nsk),
1200                                                         LINUX_MIB_TCPMIGRATEREQSUCCESS);
1201                                         reqsk_migrate_reset(req);
1202                                 } else {
1203                                         __NET_INC_STATS(sock_net(nsk),
1204                                                         LINUX_MIB_TCPMIGRATEREQFAILURE);
1205                                         reqsk_migrate_reset(nreq);
1206                                         __reqsk_free(nreq);
1207                                 }
1208
1209                                 /* inet_csk_reqsk_queue_add() has already
1210                                  * called inet_child_forget() on failure case.
1211                                  */
1212                                 goto skip_child_forget;
1213                         }
1214                 }
1215
1216                 inet_child_forget(sk, req, child);
1217 skip_child_forget:
1218                 reqsk_put(req);
1219                 bh_unlock_sock(child);
1220                 local_bh_enable();
1221                 sock_put(child);
1222
1223                 cond_resched();
1224         }
1225         if (queue->fastopenq.rskq_rst_head) {
1226                 /* Free all the reqs queued in rskq_rst_head. */
1227                 spin_lock_bh(&queue->fastopenq.lock);
1228                 req = queue->fastopenq.rskq_rst_head;
1229                 queue->fastopenq.rskq_rst_head = NULL;
1230                 spin_unlock_bh(&queue->fastopenq.lock);
1231                 while (req != NULL) {
1232                         next = req->dl_next;
1233                         reqsk_put(req);
1234                         req = next;
1235                 }
1236         }
1237         WARN_ON_ONCE(sk->sk_ack_backlog);
1238 }
1239 EXPORT_SYMBOL_GPL(inet_csk_listen_stop);
1240
1241 void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr)
1242 {
1243         struct sockaddr_in *sin = (struct sockaddr_in *)uaddr;
1244         const struct inet_sock *inet = inet_sk(sk);
1245
1246         sin->sin_family         = AF_INET;
1247         sin->sin_addr.s_addr    = inet->inet_daddr;
1248         sin->sin_port           = inet->inet_dport;
1249 }
1250 EXPORT_SYMBOL_GPL(inet_csk_addr2sockaddr);
1251
1252 static struct dst_entry *inet_csk_rebuild_route(struct sock *sk, struct flowi *fl)
1253 {
1254         const struct inet_sock *inet = inet_sk(sk);
1255         const struct ip_options_rcu *inet_opt;
1256         __be32 daddr = inet->inet_daddr;
1257         struct flowi4 *fl4;
1258         struct rtable *rt;
1259
1260         rcu_read_lock();
1261         inet_opt = rcu_dereference(inet->inet_opt);
1262         if (inet_opt && inet_opt->opt.srr)
1263                 daddr = inet_opt->opt.faddr;
1264         fl4 = &fl->u.ip4;
1265         rt = ip_route_output_ports(sock_net(sk), fl4, sk, daddr,
1266                                    inet->inet_saddr, inet->inet_dport,
1267                                    inet->inet_sport, sk->sk_protocol,
1268                                    RT_CONN_FLAGS(sk), sk->sk_bound_dev_if);
1269         if (IS_ERR(rt))
1270                 rt = NULL;
1271         if (rt)
1272                 sk_setup_caps(sk, &rt->dst);
1273         rcu_read_unlock();
1274
1275         return &rt->dst;
1276 }
1277
1278 struct dst_entry *inet_csk_update_pmtu(struct sock *sk, u32 mtu)
1279 {
1280         struct dst_entry *dst = __sk_dst_check(sk, 0);
1281         struct inet_sock *inet = inet_sk(sk);
1282
1283         if (!dst) {
1284                 dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
1285                 if (!dst)
1286                         goto out;
1287         }
1288         dst->ops->update_pmtu(dst, sk, NULL, mtu, true);
1289
1290         dst = __sk_dst_check(sk, 0);
1291         if (!dst)
1292                 dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
1293 out:
1294         return dst;
1295 }
1296 EXPORT_SYMBOL_GPL(inet_csk_update_pmtu);