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                 int bound_dev_if2;
 159
 160                 if (sk == sk2)
 161                         continue;
 162                 bound_dev_if2 = READ_ONCE(sk2->sk_bound_dev_if);
 163                 if ((!sk->sk_bound_dev_if ||
 164                      !bound_dev_if2 ||
 165                      sk->sk_bound_dev_if == bound_dev_if2)) {
 166                         if (reuse && sk2->sk_reuse &&
 167                             sk2->sk_state != TCP_LISTEN) {
 168                                 if ((!relax ||
 169                                      (!reuseport_ok &&
 170                                       reuseport && sk2->sk_reuseport &&
 171                                       reuseport_cb_ok &&
 172                                       (sk2->sk_state == TCP_TIME_WAIT ||
 173                                        uid_eq(uid, sock_i_uid(sk2))))) &&
 174                                     inet_rcv_saddr_equal(sk, sk2, true))
 175                                         break;
 176                         } else if (!reuseport_ok ||
 177                                    !reuseport || !sk2->sk_reuseport ||
 178                                    !reuseport_cb_ok ||
 179                                    (sk2->sk_state != TCP_TIME_WAIT &&
 180                                     !uid_eq(uid, sock_i_uid(sk2)))) {
 181                                 if (inet_rcv_saddr_equal(sk, sk2, true))
 182                                         break;
 183                         }
 184                 }
 185         }
 186         return sk2 != NULL;
 187 }
 188
 189 /*
 190  * Find an open port number for the socket.  Returns with the
 191  * inet_bind_hashbucket lock held.
 192  */
 193 static struct inet_bind_hashbucket *
 194 inet_csk_find_open_port(struct sock *sk, struct inet_bind_bucket **tb_ret, int *port_ret)
 195 {
 196         struct inet_hashinfo *hinfo = sk->sk_prot->h.hashinfo;
 197         int port = 0;
 198         struct inet_bind_hashbucket *head;
 199         struct net *net = sock_net(sk);
 200         bool relax = false;
 201         int i, low, high, attempt_half;
 202         struct inet_bind_bucket *tb;
 203         u32 remaining, offset;
 204         int l3mdev;
 205
 206         l3mdev = inet_sk_bound_l3mdev(sk);
 207 ports_exhausted:
 208         attempt_half = (sk->sk_reuse == SK_CAN_REUSE) ? 1 : 0;
 209 other_half_scan:
 210         inet_get_local_port_range(net, &low, &high);
 211         high++; /* [32768, 60999] -> [32768, 61000[ */
 212         if (high - low < 4)
 213                 attempt_half = 0;
 214         if (attempt_half) {
 215                 int half = low + (((high - low) >> 2) << 1);
 216
 217                 if (attempt_half == 1)
 218                         high = half;
 219                 else
 220                         low = half;
 221         }
 222         remaining = high - low;
 223         if (likely(remaining > 1))
 224                 remaining &= ~1U;
 225
 226         offset = prandom_u32() % remaining;
 227         /* __inet_hash_connect() favors ports having @low parity
 228          * We do the opposite to not pollute connect() users.
 229          */
 230         offset |= 1U;
 231
 232 other_parity_scan:
 233         port = low + offset;
 234         for (i = 0; i < remaining; i += 2, port += 2) {
 235                 if (unlikely(port >= high))
 236                         port -= remaining;
 237                 if (inet_is_local_reserved_port(net, port))
 238                         continue;
 239                 head = &hinfo->bhash[inet_bhashfn(net, port,
 240                                                   hinfo->bhash_size)];
 241                 spin_lock_bh(&head->lock);
 242                 inet_bind_bucket_for_each(tb, &head->chain)
 243                         if (net_eq(ib_net(tb), net) && tb->l3mdev == l3mdev &&
 244                             tb->port == port) {
 245                                 if (!inet_csk_bind_conflict(sk, tb, relax, false))
 246                                         goto success;
 247                                 goto next_port;
 248                         }
 249                 tb = NULL;
 250                 goto success;
 251 next_port:
 252                 spin_unlock_bh(&head->lock);
 253                 cond_resched();
 254         }
 255
 256         offset--;
 257         if (!(offset & 1))
 258                 goto other_parity_scan;
 259
 260         if (attempt_half == 1) {
 261                 /* OK we now try the upper half of the range */
 262                 attempt_half = 2;
 263                 goto other_half_scan;
 264         }
 265
 266         if (net->ipv4.sysctl_ip_autobind_reuse && !relax) {
 267                 /* We still have a chance to connect to different destinations */
 268                 relax = true;
 269                 goto ports_exhausted;
 270         }
 271         return NULL;
 272 success:
 273         *port_ret = port;
 274         *tb_ret = tb;
 275         return head;
 276 }
 277
 278 static inline int sk_reuseport_match(struct inet_bind_bucket *tb,
 279                                      struct sock *sk)
 280 {
 281         kuid_t uid = sock_i_uid(sk);
 282
 283         if (tb->fastreuseport <= 0)
 284                 return 0;
 285         if (!sk->sk_reuseport)
 286                 return 0;
 287         if (rcu_access_pointer(sk->sk_reuseport_cb))
 288                 return 0;
 289         if (!uid_eq(tb->fastuid, uid))
 290                 return 0;
 291         /* We only need to check the rcv_saddr if this tb was once marked
 292          * without fastreuseport and then was reset, as we can only know that
 293          * the fast_*rcv_saddr doesn't have any conflicts with the socks on the
 294          * owners list.
 295          */
 296         if (tb->fastreuseport == FASTREUSEPORT_ANY)
 297                 return 1;
 298 #if IS_ENABLED(CONFIG_IPV6)
 299         if (tb->fast_sk_family == AF_INET6)
 300                 return ipv6_rcv_saddr_equal(&tb->fast_v6_rcv_saddr,
 301                                             inet6_rcv_saddr(sk),
 302                                             tb->fast_rcv_saddr,
 303                                             sk->sk_rcv_saddr,
 304                                             tb->fast_ipv6_only,
 305                                             ipv6_only_sock(sk), true, false);
 306 #endif
 307         return ipv4_rcv_saddr_equal(tb->fast_rcv_saddr, sk->sk_rcv_saddr,
 308                                     ipv6_only_sock(sk), true, false);
 309 }
 310
 311 void inet_csk_update_fastreuse(struct inet_bind_bucket *tb,
 312                                struct sock *sk)
 313 {
 314         kuid_t uid = sock_i_uid(sk);
 315         bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN;
 316
 317         if (hlist_empty(&tb->owners)) {
 318                 tb->fastreuse = reuse;
 319                 if (sk->sk_reuseport) {
 320                         tb->fastreuseport = FASTREUSEPORT_ANY;
 321                         tb->fastuid = uid;
 322                         tb->fast_rcv_saddr = sk->sk_rcv_saddr;
 323                         tb->fast_ipv6_only = ipv6_only_sock(sk);
 324                         tb->fast_sk_family = sk->sk_family;
 325 #if IS_ENABLED(CONFIG_IPV6)
 326                         tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
 327 #endif
 328                 } else {
 329                         tb->fastreuseport = 0;
 330                 }
 331         } else {
 332                 if (!reuse)
 333                         tb->fastreuse = 0;
 334                 if (sk->sk_reuseport) {
 335                         /* We didn't match or we don't have fastreuseport set on
 336                          * the tb, but we have sk_reuseport set on this socket
 337                          * and we know that there are no bind conflicts with
 338                          * this socket in this tb, so reset our tb's reuseport
 339                          * settings so that any subsequent sockets that match
 340                          * our current socket will be put on the fast path.
 341                          *
 342                          * If we reset we need to set FASTREUSEPORT_STRICT so we
 343                          * do extra checking for all subsequent sk_reuseport
 344                          * socks.
 345                          */
 346                         if (!sk_reuseport_match(tb, sk)) {
 347                                 tb->fastreuseport = FASTREUSEPORT_STRICT;
 348                                 tb->fastuid = uid;
 349                                 tb->fast_rcv_saddr = sk->sk_rcv_saddr;
 350                                 tb->fast_ipv6_only = ipv6_only_sock(sk);
 351                                 tb->fast_sk_family = sk->sk_family;
 352 #if IS_ENABLED(CONFIG_IPV6)
 353                                 tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
 354 #endif
 355                         }
 356                 } else {
 357                         tb->fastreuseport = 0;
 358                 }
 359         }
 360 }
 361
 362 /* Obtain a reference to a local port for the given sock,
 363  * if snum is zero it means select any available local port.
 364  * We try to allocate an odd port (and leave even ports for connect())
 365  */
 366 int inet_csk_get_port(struct sock *sk, unsigned short snum)
 367 {
 368         bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN;
 369         struct inet_hashinfo *hinfo = sk->sk_prot->h.hashinfo;
 370         int ret = 1, port = snum;
 371         struct inet_bind_hashbucket *head;
 372         struct net *net = sock_net(sk);
 373         struct inet_bind_bucket *tb = NULL;
 374         int l3mdev;
 375
 376         l3mdev = inet_sk_bound_l3mdev(sk);
 377
 378         if (!port) {
 379                 head = inet_csk_find_open_port(sk, &tb, &port);
 380                 if (!head)
 381                         return ret;
 382                 if (!tb)
 383                         goto tb_not_found;
 384                 goto success;
 385         }
 386         head = &hinfo->bhash[inet_bhashfn(net, port,
 387                                           hinfo->bhash_size)];
 388         spin_lock_bh(&head->lock);
 389         inet_bind_bucket_for_each(tb, &head->chain)
 390                 if (net_eq(ib_net(tb), net) && tb->l3mdev == l3mdev &&
 391                     tb->port == port)
 392                         goto tb_found;
 393 tb_not_found:
 394         tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep,
 395                                      net, head, port, l3mdev);
 396         if (!tb)
 397                 goto fail_unlock;
 398 tb_found:
 399         if (!hlist_empty(&tb->owners)) {
 400                 if (sk->sk_reuse == SK_FORCE_REUSE)
 401                         goto success;
 402
 403                 if ((tb->fastreuse > 0 && reuse) ||
 404                     sk_reuseport_match(tb, sk))
 405                         goto success;
 406                 if (inet_csk_bind_conflict(sk, tb, true, true))
 407                         goto fail_unlock;
 408         }
 409 success:
 410         inet_csk_update_fastreuse(tb, sk);
 411
 412         if (!inet_csk(sk)->icsk_bind_hash)
 413                 inet_bind_hash(sk, tb, port);
 414         WARN_ON(inet_csk(sk)->icsk_bind_hash != tb);
 415         ret = 0;
 416
 417 fail_unlock:
 418         spin_unlock_bh(&head->lock);
 419         return ret;
 420 }
 421 EXPORT_SYMBOL_GPL(inet_csk_get_port);
 422
 423 /*
 424  * Wait for an incoming connection, avoid race conditions. This must be called
 425  * with the socket locked.
 426  */
 427 static int inet_csk_wait_for_connect(struct sock *sk, long timeo)
 428 {
 429         struct inet_connection_sock *icsk = inet_csk(sk);
 430         DEFINE_WAIT(wait);
 431         int err;
 432
 433         /*
 434          * True wake-one mechanism for incoming connections: only
 435          * one process gets woken up, not the 'whole herd'.
 436          * Since we do not 'race & poll' for established sockets
 437          * anymore, the common case will execute the loop only once.
 438          *
 439          * Subtle issue: "add_wait_queue_exclusive()" will be added
 440          * after any current non-exclusive waiters, and we know that
 441          * it will always _stay_ after any new non-exclusive waiters
 442          * because all non-exclusive waiters are added at the
 443          * beginning of the wait-queue. As such, it's ok to "drop"
 444          * our exclusiveness temporarily when we get woken up without
 445          * having to remove and re-insert us on the wait queue.
 446          */
 447         for (;;) {
 448                 prepare_to_wait_exclusive(sk_sleep(sk), &wait,
 449                                           TASK_INTERRUPTIBLE);
 450                 release_sock(sk);
 451                 if (reqsk_queue_empty(&icsk->icsk_accept_queue))
 452                         timeo = schedule_timeout(timeo);
 453                 sched_annotate_sleep();
 454                 lock_sock(sk);
 455                 err = 0;
 456                 if (!reqsk_queue_empty(&icsk->icsk_accept_queue))
 457                         break;
 458                 err = -EINVAL;
 459                 if (sk->sk_state != TCP_LISTEN)
 460                         break;
 461                 err = sock_intr_errno(timeo);
 462                 if (signal_pending(current))
 463                         break;
 464                 err = -EAGAIN;
 465                 if (!timeo)
 466                         break;
 467         }
 468         finish_wait(sk_sleep(sk), &wait);
 469         return err;
 470 }
 471
 472 /*
 473  * This will accept the next outstanding connection.
 474  */
 475 struct sock *inet_csk_accept(struct sock *sk, int flags, int *err, bool kern)
 476 {
 477         struct inet_connection_sock *icsk = inet_csk(sk);
 478         struct request_sock_queue *queue = &icsk->icsk_accept_queue;
 479         struct request_sock *req;
 480         struct sock *newsk;
 481         int error;
 482
 483         lock_sock(sk);
 484
 485         /* We need to make sure that this socket is listening,
 486          * and that it has something pending.
 487          */
 488         error = -EINVAL;
 489         if (sk->sk_state != TCP_LISTEN)
 490                 goto out_err;
 491
 492         /* Find already established connection */
 493         if (reqsk_queue_empty(queue)) {
 494                 long timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);
 495
 496                 /* If this is a non blocking socket don't sleep */
 497                 error = -EAGAIN;
 498                 if (!timeo)
 499                         goto out_err;
 500
 501                 error = inet_csk_wait_for_connect(sk, timeo);
 502                 if (error)
 503                         goto out_err;
 504         }
 505         req = reqsk_queue_remove(queue, sk);
 506         newsk = req->sk;
 507
 508         if (sk->sk_protocol == IPPROTO_TCP &&
 509             tcp_rsk(req)->tfo_listener) {
 510                 spin_lock_bh(&queue->fastopenq.lock);
 511                 if (tcp_rsk(req)->tfo_listener) {
 512                         /* We are still waiting for the final ACK from 3WHS
 513                          * so can't free req now. Instead, we set req->sk to
 514                          * NULL to signify that the child socket is taken
 515                          * so reqsk_fastopen_remove() will free the req
 516                          * when 3WHS finishes (or is aborted).
 517                          */
 518                         req->sk = NULL;
 519                         req = NULL;
 520                 }
 521                 spin_unlock_bh(&queue->fastopenq.lock);
 522         }
 523
 524 out:
 525         release_sock(sk);
 526         if (newsk && mem_cgroup_sockets_enabled) {
 527                 int amt;
 528
 529                 /* atomically get the memory usage, set and charge the
 530                  * newsk->sk_memcg.
 531                  */
 532                 lock_sock(newsk);
 533
 534                 /* The socket has not been accepted yet, no need to look at
 535                  * newsk->sk_wmem_queued.
 536                  */
 537                 amt = sk_mem_pages(newsk->sk_forward_alloc +
 538                                    atomic_read(&newsk->sk_rmem_alloc));
 539                 mem_cgroup_sk_alloc(newsk);
 540                 if (newsk->sk_memcg && amt)
 541                         mem_cgroup_charge_skmem(newsk->sk_memcg, amt,
 542                                                 GFP_KERNEL | __GFP_NOFAIL);
 543
 544                 release_sock(newsk);
 545         }
 546         if (req)
 547                 reqsk_put(req);
 548         return newsk;
 549 out_err:
 550         newsk = NULL;
 551         req = NULL;
 552         *err = error;
 553         goto out;
 554 }
 555 EXPORT_SYMBOL(inet_csk_accept);
 556
 557 /*
 558  * Using different timers for retransmit, delayed acks and probes
 559  * We may wish use just one timer maintaining a list of expire jiffies
 560  * to optimize.
 561  */
 562 void inet_csk_init_xmit_timers(struct sock *sk,
 563                                void (*retransmit_handler)(struct timer_list *t),
 564                                void (*delack_handler)(struct timer_list *t),
 565                                void (*keepalive_handler)(struct timer_list *t))
 566 {
 567         struct inet_connection_sock *icsk = inet_csk(sk);
 568
 569         timer_setup(&icsk->icsk_retransmit_timer, retransmit_handler, 0);
 570         timer_setup(&icsk->icsk_delack_timer, delack_handler, 0);
 571         timer_setup(&sk->sk_timer, keepalive_handler, 0);
 572         icsk->icsk_pending = icsk->icsk_ack.pending = 0;
 573 }
 574 EXPORT_SYMBOL(inet_csk_init_xmit_timers);
 575
 576 void inet_csk_clear_xmit_timers(struct sock *sk)
 577 {
 578         struct inet_connection_sock *icsk = inet_csk(sk);
 579
 580         icsk->icsk_pending = icsk->icsk_ack.pending = 0;
 581
 582         sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
 583         sk_stop_timer(sk, &icsk->icsk_delack_timer);
 584         sk_stop_timer(sk, &sk->sk_timer);
 585 }
 586 EXPORT_SYMBOL(inet_csk_clear_xmit_timers);
 587
 588 void inet_csk_delete_keepalive_timer(struct sock *sk)
 589 {
 590         sk_stop_timer(sk, &sk->sk_timer);
 591 }
 592 EXPORT_SYMBOL(inet_csk_delete_keepalive_timer);
 593
 594 void inet_csk_reset_keepalive_timer(struct sock *sk, unsigned long len)
 595 {
 596         sk_reset_timer(sk, &sk->sk_timer, jiffies + len);
 597 }
 598 EXPORT_SYMBOL(inet_csk_reset_keepalive_timer);
 599
 600 struct dst_entry *inet_csk_route_req(const struct sock *sk,
 601                                      struct flowi4 *fl4,
 602                                      const struct request_sock *req)
 603 {
 604         const struct inet_request_sock *ireq = inet_rsk(req);
 605         struct net *net = read_pnet(&ireq->ireq_net);
 606         struct ip_options_rcu *opt;
 607         struct rtable *rt;
 608
 609         rcu_read_lock();
 610         opt = rcu_dereference(ireq->ireq_opt);
 611
 612         flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
 613                            RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
 614                            sk->sk_protocol, inet_sk_flowi_flags(sk),
 615                            (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
 616                            ireq->ir_loc_addr, ireq->ir_rmt_port,
 617                            htons(ireq->ir_num), sk->sk_uid);
 618         security_req_classify_flow(req, flowi4_to_flowi_common(fl4));
 619         rt = ip_route_output_flow(net, fl4, sk);
 620         if (IS_ERR(rt))
 621                 goto no_route;
 622         if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
 623                 goto route_err;
 624         rcu_read_unlock();
 625         return &rt->dst;
 626
 627 route_err:
 628         ip_rt_put(rt);
 629 no_route:
 630         rcu_read_unlock();
 631         __IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
 632         return NULL;
 633 }
 634 EXPORT_SYMBOL_GPL(inet_csk_route_req);
 635
 636 struct dst_entry *inet_csk_route_child_sock(const struct sock *sk,
 637                                             struct sock *newsk,
 638                                             const struct request_sock *req)
 639 {
 640         const struct inet_request_sock *ireq = inet_rsk(req);
 641         struct net *net = read_pnet(&ireq->ireq_net);
 642         struct inet_sock *newinet = inet_sk(newsk);
 643         struct ip_options_rcu *opt;
 644         struct flowi4 *fl4;
 645         struct rtable *rt;
 646
 647         opt = rcu_dereference(ireq->ireq_opt);
 648         fl4 = &newinet->cork.fl.u.ip4;
 649
 650         flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
 651                            RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
 652                            sk->sk_protocol, inet_sk_flowi_flags(sk),
 653                            (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
 654                            ireq->ir_loc_addr, ireq->ir_rmt_port,
 655                            htons(ireq->ir_num), sk->sk_uid);
 656         security_req_classify_flow(req, flowi4_to_flowi_common(fl4));
 657         rt = ip_route_output_flow(net, fl4, sk);
 658         if (IS_ERR(rt))
 659                 goto no_route;
 660         if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
 661                 goto route_err;
 662         return &rt->dst;
 663
 664 route_err:
 665         ip_rt_put(rt);
 666 no_route:
 667         __IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
 668         return NULL;
 669 }
 670 EXPORT_SYMBOL_GPL(inet_csk_route_child_sock);
 671
 672 /* Decide when to expire the request and when to resend SYN-ACK */
 673 static void syn_ack_recalc(struct request_sock *req,
 674                            const int max_syn_ack_retries,
 675                            const u8 rskq_defer_accept,
 676                            int *expire, int *resend)
 677 {
 678         if (!rskq_defer_accept) {
 679                 *expire = req->num_timeout >= max_syn_ack_retries;
 680                 *resend = 1;
 681                 return;
 682         }
 683         *expire = req->num_timeout >= max_syn_ack_retries &&
 684                   (!inet_rsk(req)->acked || req->num_timeout >= rskq_defer_accept);
 685         /* Do not resend while waiting for data after ACK,
 686          * start to resend on end of deferring period to give
 687          * last chance for data or ACK to create established socket.
 688          */
 689         *resend = !inet_rsk(req)->acked ||
 690                   req->num_timeout >= rskq_defer_accept - 1;
 691 }
 692
 693 int inet_rtx_syn_ack(const struct sock *parent, struct request_sock *req)
 694 {
 695         int err = req->rsk_ops->rtx_syn_ack(parent, req);
 696
 697         if (!err)
 698                 req->num_retrans++;
 699         return err;
 700 }
 701 EXPORT_SYMBOL(inet_rtx_syn_ack);
 702
 703 static struct request_sock *inet_reqsk_clone(struct request_sock *req,
 704                                              struct sock *sk)
 705 {
 706         struct sock *req_sk, *nreq_sk;
 707         struct request_sock *nreq;
 708
 709         nreq = kmem_cache_alloc(req->rsk_ops->slab, GFP_ATOMIC | __GFP_NOWARN);
 710         if (!nreq) {
 711                 __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQFAILURE);
 712
 713                 /* paired with refcount_inc_not_zero() in reuseport_migrate_sock() */
 714                 sock_put(sk);
 715                 return NULL;
 716         }
 717
 718         req_sk = req_to_sk(req);
 719         nreq_sk = req_to_sk(nreq);
 720
 721         memcpy(nreq_sk, req_sk,
 722                offsetof(struct sock, sk_dontcopy_begin));
 723         memcpy(&nreq_sk->sk_dontcopy_end, &req_sk->sk_dontcopy_end,
 724                req->rsk_ops->obj_size - offsetof(struct sock, sk_dontcopy_end));
 725
 726         sk_node_init(&nreq_sk->sk_node);
 727         nreq_sk->sk_tx_queue_mapping = req_sk->sk_tx_queue_mapping;
 728 #ifdef CONFIG_SOCK_RX_QUEUE_MAPPING
 729         nreq_sk->sk_rx_queue_mapping = req_sk->sk_rx_queue_mapping;
 730 #endif
 731         nreq_sk->sk_incoming_cpu = req_sk->sk_incoming_cpu;
 732
 733         nreq->rsk_listener = sk;
 734
 735         /* We need not acquire fastopenq->lock
 736          * because the child socket is locked in inet_csk_listen_stop().
 737          */
 738         if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(nreq)->tfo_listener)
 739                 rcu_assign_pointer(tcp_sk(nreq->sk)->fastopen_rsk, nreq);
 740
 741         return nreq;
 742 }
 743
 744 static void reqsk_queue_migrated(struct request_sock_queue *queue,
 745                                  const struct request_sock *req)
 746 {
 747         if (req->num_timeout == 0)
 748                 atomic_inc(&queue->young);
 749         atomic_inc(&queue->qlen);
 750 }
 751
 752 static void reqsk_migrate_reset(struct request_sock *req)
 753 {
 754         req->saved_syn = NULL;
 755 #if IS_ENABLED(CONFIG_IPV6)
 756         inet_rsk(req)->ipv6_opt = NULL;
 757         inet_rsk(req)->pktopts = NULL;
 758 #else
 759         inet_rsk(req)->ireq_opt = NULL;
 760 #endif
 761 }
 762
 763 /* return true if req was found in the ehash table */
 764 static bool reqsk_queue_unlink(struct request_sock *req)
 765 {
 766         struct inet_hashinfo *hashinfo = req_to_sk(req)->sk_prot->h.hashinfo;
 767         bool found = false;
 768
 769         if (sk_hashed(req_to_sk(req))) {
 770                 spinlock_t *lock = inet_ehash_lockp(hashinfo, req->rsk_hash);
 771
 772                 spin_lock(lock);
 773                 found = __sk_nulls_del_node_init_rcu(req_to_sk(req));
 774                 spin_unlock(lock);
 775         }
 776         if (timer_pending(&req->rsk_timer) && del_timer_sync(&req->rsk_timer))
 777                 reqsk_put(req);
 778         return found;
 779 }
 780
 781 bool inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req)
 782 {
 783         bool unlinked = reqsk_queue_unlink(req);
 784
 785         if (unlinked) {
 786                 reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req);
 787                 reqsk_put(req);
 788         }
 789         return unlinked;
 790 }
 791 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop);
 792
 793 void inet_csk_reqsk_queue_drop_and_put(struct sock *sk, struct request_sock *req)
 794 {
 795         inet_csk_reqsk_queue_drop(sk, req);
 796         reqsk_put(req);
 797 }
 798 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop_and_put);
 799
 800 static void reqsk_timer_handler(struct timer_list *t)
 801 {
 802         struct request_sock *req = from_timer(req, t, rsk_timer);
 803         struct request_sock *nreq = NULL, *oreq = req;
 804         struct sock *sk_listener = req->rsk_listener;
 805         struct inet_connection_sock *icsk;
 806         struct request_sock_queue *queue;
 807         struct net *net;
 808         int max_syn_ack_retries, qlen, expire = 0, resend = 0;
 809
 810         if (inet_sk_state_load(sk_listener) != TCP_LISTEN) {
 811                 struct sock *nsk;
 812
 813                 nsk = reuseport_migrate_sock(sk_listener, req_to_sk(req), NULL);
 814                 if (!nsk)
 815                         goto drop;
 816
 817                 nreq = inet_reqsk_clone(req, nsk);
 818                 if (!nreq)
 819                         goto drop;
 820
 821                 /* The new timer for the cloned req can decrease the 2
 822                  * by calling inet_csk_reqsk_queue_drop_and_put(), so
 823                  * hold another count to prevent use-after-free and
 824                  * call reqsk_put() just before return.
 825                  */
 826                 refcount_set(&nreq->rsk_refcnt, 2 + 1);
 827                 timer_setup(&nreq->rsk_timer, reqsk_timer_handler, TIMER_PINNED);
 828                 reqsk_queue_migrated(&inet_csk(nsk)->icsk_accept_queue, req);
 829
 830                 req = nreq;
 831                 sk_listener = nsk;
 832         }
 833
 834         icsk = inet_csk(sk_listener);
 835         net = sock_net(sk_listener);
 836         max_syn_ack_retries = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_synack_retries;
 837         /* Normally all the openreqs are young and become mature
 838          * (i.e. converted to established socket) for first timeout.
 839          * If synack was not acknowledged for 1 second, it means
 840          * one of the following things: synack was lost, ack was lost,
 841          * rtt is high or nobody planned to ack (i.e. synflood).
 842          * When server is a bit loaded, queue is populated with old
 843          * open requests, reducing effective size of queue.
 844          * When server is well loaded, queue size reduces to zero
 845          * after several minutes of work. It is not synflood,
 846          * it is normal operation. The solution is pruning
 847          * too old entries overriding normal timeout, when
 848          * situation becomes dangerous.
 849          *
 850          * Essentially, we reserve half of room for young
 851          * embrions; and abort old ones without pity, if old
 852          * ones are about to clog our table.
 853          */
 854         queue = &icsk->icsk_accept_queue;
 855         qlen = reqsk_queue_len(queue);
 856         if ((qlen << 1) > max(8U, READ_ONCE(sk_listener->sk_max_ack_backlog))) {
 857                 int young = reqsk_queue_len_young(queue) << 1;
 858
 859                 while (max_syn_ack_retries > 2) {
 860                         if (qlen < young)
 861                                 break;
 862                         max_syn_ack_retries--;
 863                         young <<= 1;
 864                 }
 865         }
 866         syn_ack_recalc(req, max_syn_ack_retries, READ_ONCE(queue->rskq_defer_accept),
 867                        &expire, &resend);
 868         req->rsk_ops->syn_ack_timeout(req);
 869         if (!expire &&
 870             (!resend ||
 871              !inet_rtx_syn_ack(sk_listener, req) ||
 872              inet_rsk(req)->acked)) {
 873                 if (req->num_timeout++ == 0)
 874                         atomic_dec(&queue->young);
 875                 mod_timer(&req->rsk_timer, jiffies + reqsk_timeout(req, TCP_RTO_MAX));
 876
 877                 if (!nreq)
 878                         return;
 879
 880                 if (!inet_ehash_insert(req_to_sk(nreq), req_to_sk(oreq), NULL)) {
 881                         /* delete timer */
 882                         inet_csk_reqsk_queue_drop(sk_listener, nreq);
 883                         goto no_ownership;
 884                 }
 885
 886                 __NET_INC_STATS(net, LINUX_MIB_TCPMIGRATEREQSUCCESS);
 887                 reqsk_migrate_reset(oreq);
 888                 reqsk_queue_removed(&inet_csk(oreq->rsk_listener)->icsk_accept_queue, oreq);
 889                 reqsk_put(oreq);
 890
 891                 reqsk_put(nreq);
 892                 return;
 893         }
 894
 895         /* Even if we can clone the req, we may need not retransmit any more
 896          * SYN+ACKs (nreq->num_timeout > max_syn_ack_retries, etc), or another
 897          * CPU may win the "own_req" race so that inet_ehash_insert() fails.
 898          */
 899         if (nreq) {
 900                 __NET_INC_STATS(net, LINUX_MIB_TCPMIGRATEREQFAILURE);
 901 no_ownership:
 902                 reqsk_migrate_reset(nreq);
 903                 reqsk_queue_removed(queue, nreq);
 904                 __reqsk_free(nreq);
 905         }
 906
 907 drop:
 908         inet_csk_reqsk_queue_drop_and_put(oreq->rsk_listener, oreq);
 909 }
 910
 911 static void reqsk_queue_hash_req(struct request_sock *req,
 912                                  unsigned long timeout)
 913 {
 914         timer_setup(&req->rsk_timer, reqsk_timer_handler, TIMER_PINNED);
 915         mod_timer(&req->rsk_timer, jiffies + timeout);
 916
 917         inet_ehash_insert(req_to_sk(req), NULL, NULL);
 918         /* before letting lookups find us, make sure all req fields
 919          * are committed to memory and refcnt initialized.
 920          */
 921         smp_wmb();
 922         refcount_set(&req->rsk_refcnt, 2 + 1);
 923 }
 924
 925 void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
 926                                    unsigned long timeout)
 927 {
 928         reqsk_queue_hash_req(req, timeout);
 929         inet_csk_reqsk_queue_added(sk);
 930 }
 931 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add);
 932
 933 static void inet_clone_ulp(const struct request_sock *req, struct sock *newsk,
 934                            const gfp_t priority)
 935 {
 936         struct inet_connection_sock *icsk = inet_csk(newsk);
 937
 938         if (!icsk->icsk_ulp_ops)
 939                 return;
 940
 941         if (icsk->icsk_ulp_ops->clone)
 942                 icsk->icsk_ulp_ops->clone(req, newsk, priority);
 943 }
 944
 945 /**
 946  *      inet_csk_clone_lock - clone an inet socket, and lock its clone
 947  *      @sk: the socket to clone
 948  *      @req: request_sock
 949  *      @priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc)
 950  *
 951  *      Caller must unlock socket even in error path (bh_unlock_sock(newsk))
 952  */
 953 struct sock *inet_csk_clone_lock(const struct sock *sk,
 954                                  const struct request_sock *req,
 955                                  const gfp_t priority)
 956 {
 957         struct sock *newsk = sk_clone_lock(sk, priority);
 958
 959         if (newsk) {
 960                 struct inet_connection_sock *newicsk = inet_csk(newsk);
 961
 962                 inet_sk_set_state(newsk, TCP_SYN_RECV);
 963                 newicsk->icsk_bind_hash = NULL;
 964
 965                 inet_sk(newsk)->inet_dport = inet_rsk(req)->ir_rmt_port;
 966                 inet_sk(newsk)->inet_num = inet_rsk(req)->ir_num;
 967                 inet_sk(newsk)->inet_sport = htons(inet_rsk(req)->ir_num);
 968
 969                 /* listeners have SOCK_RCU_FREE, not the children */
 970                 sock_reset_flag(newsk, SOCK_RCU_FREE);
 971
 972                 inet_sk(newsk)->mc_list = NULL;
 973
 974                 newsk->sk_mark = inet_rsk(req)->ir_mark;
 975                 atomic64_set(&newsk->sk_cookie,
 976                              atomic64_read(&inet_rsk(req)->ir_cookie));
 977
 978                 newicsk->icsk_retransmits = 0;
 979                 newicsk->icsk_backoff     = 0;
 980                 newicsk->icsk_probes_out  = 0;
 981                 newicsk->icsk_probes_tstamp = 0;
 982
 983                 /* Deinitialize accept_queue to trap illegal accesses. */
 984                 memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue));
 985
 986                 inet_clone_ulp(req, newsk, priority);
 987
 988                 security_inet_csk_clone(newsk, req);
 989         }
 990         return newsk;
 991 }
 992 EXPORT_SYMBOL_GPL(inet_csk_clone_lock);
 993
 994 /*
 995  * At this point, there should be no process reference to this
 996  * socket, and thus no user references at all.  Therefore we
 997  * can assume the socket waitqueue is inactive and nobody will
 998  * try to jump onto it.
 999  */
1000 void inet_csk_destroy_sock(struct sock *sk)
1001 {
1002         WARN_ON(sk->sk_state != TCP_CLOSE);
1003         WARN_ON(!sock_flag(sk, SOCK_DEAD));
1004
1005         /* It cannot be in hash table! */
1006         WARN_ON(!sk_unhashed(sk));
1007
1008         /* If it has not 0 inet_sk(sk)->inet_num, it must be bound */
1009         WARN_ON(inet_sk(sk)->inet_num && !inet_csk(sk)->icsk_bind_hash);
1010
1011         sk->sk_prot->destroy(sk);
1012
1013         sk_stream_kill_queues(sk);
1014
1015         xfrm_sk_free_policy(sk);
1016
1017         sk_refcnt_debug_release(sk);
1018
1019         this_cpu_dec(*sk->sk_prot->orphan_count);
1020
1021         sock_put(sk);
1022 }
1023 EXPORT_SYMBOL(inet_csk_destroy_sock);
1024
1025 /* This function allows to force a closure of a socket after the call to
1026  * tcp/dccp_create_openreq_child().
1027  */
1028 void inet_csk_prepare_forced_close(struct sock *sk)
1029         __releases(&sk->sk_lock.slock)
1030 {
1031         /* sk_clone_lock locked the socket and set refcnt to 2 */
1032         bh_unlock_sock(sk);
1033         sock_put(sk);
1034         inet_csk_prepare_for_destroy_sock(sk);
1035         inet_sk(sk)->inet_num = 0;
1036 }
1037 EXPORT_SYMBOL(inet_csk_prepare_forced_close);
1038
1039 int inet_csk_listen_start(struct sock *sk)
1040 {
1041         struct inet_connection_sock *icsk = inet_csk(sk);
1042         struct inet_sock *inet = inet_sk(sk);
1043         int err = -EADDRINUSE;
1044
1045         reqsk_queue_alloc(&icsk->icsk_accept_queue);
1046
1047         sk->sk_ack_backlog = 0;
1048         inet_csk_delack_init(sk);
1049
1050         if (sk->sk_txrehash == SOCK_TXREHASH_DEFAULT)
1051                 sk->sk_txrehash = READ_ONCE(sock_net(sk)->core.sysctl_txrehash);
1052
1053         /* There is race window here: we announce ourselves listening,
1054          * but this transition is still not validated by get_port().
1055          * It is OK, because this socket enters to hash table only
1056          * after validation is complete.
1057          */
1058         inet_sk_state_store(sk, TCP_LISTEN);
1059         if (!sk->sk_prot->get_port(sk, inet->inet_num)) {
1060                 inet->inet_sport = htons(inet->inet_num);
1061
1062                 sk_dst_reset(sk);
1063                 err = sk->sk_prot->hash(sk);
1064
1065                 if (likely(!err))
1066                         return 0;
1067         }
1068
1069         inet_sk_set_state(sk, TCP_CLOSE);
1070         return err;
1071 }
1072 EXPORT_SYMBOL_GPL(inet_csk_listen_start);
1073
1074 static void inet_child_forget(struct sock *sk, struct request_sock *req,
1075                               struct sock *child)
1076 {
1077         sk->sk_prot->disconnect(child, O_NONBLOCK);
1078
1079         sock_orphan(child);
1080
1081         this_cpu_inc(*sk->sk_prot->orphan_count);
1082
1083         if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(req)->tfo_listener) {
1084                 BUG_ON(rcu_access_pointer(tcp_sk(child)->fastopen_rsk) != req);
1085                 BUG_ON(sk != req->rsk_listener);
1086
1087                 /* Paranoid, to prevent race condition if
1088                  * an inbound pkt destined for child is
1089                  * blocked by sock lock in tcp_v4_rcv().
1090                  * Also to satisfy an assertion in
1091                  * tcp_v4_destroy_sock().
1092                  */
1093                 RCU_INIT_POINTER(tcp_sk(child)->fastopen_rsk, NULL);
1094         }
1095         inet_csk_destroy_sock(child);
1096 }
1097
1098 struct sock *inet_csk_reqsk_queue_add(struct sock *sk,
1099                                       struct request_sock *req,
1100                                       struct sock *child)
1101 {
1102         struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
1103
1104         spin_lock(&queue->rskq_lock);
1105         if (unlikely(sk->sk_state != TCP_LISTEN)) {
1106                 inet_child_forget(sk, req, child);
1107                 child = NULL;
1108         } else {
1109                 req->sk = child;
1110                 req->dl_next = NULL;
1111                 if (queue->rskq_accept_head == NULL)
1112                         WRITE_ONCE(queue->rskq_accept_head, req);
1113                 else
1114                         queue->rskq_accept_tail->dl_next = req;
1115                 queue->rskq_accept_tail = req;
1116                 sk_acceptq_added(sk);
1117         }
1118         spin_unlock(&queue->rskq_lock);
1119         return child;
1120 }
1121 EXPORT_SYMBOL(inet_csk_reqsk_queue_add);
1122
1123 struct sock *inet_csk_complete_hashdance(struct sock *sk, struct sock *child,
1124                                          struct request_sock *req, bool own_req)
1125 {
1126         if (own_req) {
1127                 inet_csk_reqsk_queue_drop(req->rsk_listener, req);
1128                 reqsk_queue_removed(&inet_csk(req->rsk_listener)->icsk_accept_queue, req);
1129
1130                 if (sk != req->rsk_listener) {
1131                         /* another listening sk has been selected,
1132                          * migrate the req to it.
1133                          */
1134                         struct request_sock *nreq;
1135
1136                         /* hold a refcnt for the nreq->rsk_listener
1137                          * which is assigned in inet_reqsk_clone()
1138                          */
1139                         sock_hold(sk);
1140                         nreq = inet_reqsk_clone(req, sk);
1141                         if (!nreq) {
1142                                 inet_child_forget(sk, req, child);
1143                                 goto child_put;
1144                         }
1145
1146                         refcount_set(&nreq->rsk_refcnt, 1);
1147                         if (inet_csk_reqsk_queue_add(sk, nreq, child)) {
1148                                 __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQSUCCESS);
1149                                 reqsk_migrate_reset(req);
1150                                 reqsk_put(req);
1151                                 return child;
1152                         }
1153
1154                         __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQFAILURE);
1155                         reqsk_migrate_reset(nreq);
1156                         __reqsk_free(nreq);
1157                 } else if (inet_csk_reqsk_queue_add(sk, req, child)) {
1158                         return child;
1159                 }
1160         }
1161         /* Too bad, another child took ownership of the request, undo. */
1162 child_put:
1163         bh_unlock_sock(child);
1164         sock_put(child);
1165         return NULL;
1166 }
1167 EXPORT_SYMBOL(inet_csk_complete_hashdance);
1168
1169 /*
1170  *      This routine closes sockets which have been at least partially
1171  *      opened, but not yet accepted.
1172  */
1173 void inet_csk_listen_stop(struct sock *sk)
1174 {
1175         struct inet_connection_sock *icsk = inet_csk(sk);
1176         struct request_sock_queue *queue = &icsk->icsk_accept_queue;
1177         struct request_sock *next, *req;
1178
1179         /* Following specs, it would be better either to send FIN
1180          * (and enter FIN-WAIT-1, it is normal close)
1181          * or to send active reset (abort).
1182          * Certainly, it is pretty dangerous while synflood, but it is
1183          * bad justification for our negligence 8)
1184          * To be honest, we are not able to make either
1185          * of the variants now.                 --ANK
1186          */
1187         while ((req = reqsk_queue_remove(queue, sk)) != NULL) {
1188                 struct sock *child = req->sk, *nsk;
1189                 struct request_sock *nreq;
1190
1191                 local_bh_disable();
1192                 bh_lock_sock(child);
1193                 WARN_ON(sock_owned_by_user(child));
1194                 sock_hold(child);
1195
1196                 nsk = reuseport_migrate_sock(sk, child, NULL);
1197                 if (nsk) {
1198                         nreq = inet_reqsk_clone(req, nsk);
1199                         if (nreq) {
1200                                 refcount_set(&nreq->rsk_refcnt, 1);
1201
1202                                 if (inet_csk_reqsk_queue_add(nsk, nreq, child)) {
1203                                         __NET_INC_STATS(sock_net(nsk),
1204                                                         LINUX_MIB_TCPMIGRATEREQSUCCESS);
1205                                         reqsk_migrate_reset(req);
1206                                 } else {
1207                                         __NET_INC_STATS(sock_net(nsk),
1208                                                         LINUX_MIB_TCPMIGRATEREQFAILURE);
1209                                         reqsk_migrate_reset(nreq);
1210                                         __reqsk_free(nreq);
1211                                 }
1212
1213                                 /* inet_csk_reqsk_queue_add() has already
1214                                  * called inet_child_forget() on failure case.
1215                                  */
1216                                 goto skip_child_forget;
1217                         }
1218                 }
1219
1220                 inet_child_forget(sk, req, child);
1221 skip_child_forget:
1222                 reqsk_put(req);
1223                 bh_unlock_sock(child);
1224                 local_bh_enable();
1225                 sock_put(child);
1226
1227                 cond_resched();
1228         }
1229         if (queue->fastopenq.rskq_rst_head) {
1230                 /* Free all the reqs queued in rskq_rst_head. */
1231                 spin_lock_bh(&queue->fastopenq.lock);
1232                 req = queue->fastopenq.rskq_rst_head;
1233                 queue->fastopenq.rskq_rst_head = NULL;
1234                 spin_unlock_bh(&queue->fastopenq.lock);
1235                 while (req != NULL) {
1236                         next = req->dl_next;
1237                         reqsk_put(req);
1238                         req = next;
1239                 }
1240         }
1241         WARN_ON_ONCE(sk->sk_ack_backlog);
1242 }
1243 EXPORT_SYMBOL_GPL(inet_csk_listen_stop);
1244
1245 void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr)
1246 {
1247         struct sockaddr_in *sin = (struct sockaddr_in *)uaddr;
1248         const struct inet_sock *inet = inet_sk(sk);
1249
1250         sin->sin_family         = AF_INET;
1251         sin->sin_addr.s_addr    = inet->inet_daddr;
1252         sin->sin_port           = inet->inet_dport;
1253 }
1254 EXPORT_SYMBOL_GPL(inet_csk_addr2sockaddr);
1255
1256 static struct dst_entry *inet_csk_rebuild_route(struct sock *sk, struct flowi *fl)
1257 {
1258         const struct inet_sock *inet = inet_sk(sk);
1259         const struct ip_options_rcu *inet_opt;
1260         __be32 daddr = inet->inet_daddr;
1261         struct flowi4 *fl4;
1262         struct rtable *rt;
1263
1264         rcu_read_lock();
1265         inet_opt = rcu_dereference(inet->inet_opt);
1266         if (inet_opt && inet_opt->opt.srr)
1267                 daddr = inet_opt->opt.faddr;
1268         fl4 = &fl->u.ip4;
1269         rt = ip_route_output_ports(sock_net(sk), fl4, sk, daddr,
1270                                    inet->inet_saddr, inet->inet_dport,
1271                                    inet->inet_sport, sk->sk_protocol,
1272                                    RT_CONN_FLAGS(sk), sk->sk_bound_dev_if);
1273         if (IS_ERR(rt))
1274                 rt = NULL;
1275         if (rt)
1276                 sk_setup_caps(sk, &rt->dst);
1277         rcu_read_unlock();
1278
1279         return &rt->dst;
1280 }
1281
1282 struct dst_entry *inet_csk_update_pmtu(struct sock *sk, u32 mtu)
1283 {
1284         struct dst_entry *dst = __sk_dst_check(sk, 0);
1285         struct inet_sock *inet = inet_sk(sk);
1286
1287         if (!dst) {
1288                 dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
1289                 if (!dst)
1290                         goto out;
1291         }
1292         dst->ops->update_pmtu(dst, sk, NULL, mtu, true);
1293
1294         dst = __sk_dst_check(sk, 0);
1295         if (!dst)
1296                 dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
1297 out:
1298         return dst;
1299 }
1300 EXPORT_SYMBOL_GPL(inet_csk_update_pmtu);