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 static bool use_bhash2_on_bind(const struct sock *sk)
 121 {
 122 #if IS_ENABLED(CONFIG_IPV6)
 123         int addr_type;
 124
 125         if (sk->sk_family == AF_INET6) {
 126                 addr_type = ipv6_addr_type(&sk->sk_v6_rcv_saddr);
 127                 return addr_type != IPV6_ADDR_ANY &&
 128                         addr_type != IPV6_ADDR_MAPPED;
 129         }
 130 #endif
 131         return sk->sk_rcv_saddr != htonl(INADDR_ANY);
 132 }
 133
 134 static u32 get_bhash2_nulladdr_hash(const struct sock *sk, struct net *net,
 135                                     int port)
 136 {
 137 #if IS_ENABLED(CONFIG_IPV6)
 138         struct in6_addr nulladdr = {};
 139
 140         if (sk->sk_family == AF_INET6)
 141                 return ipv6_portaddr_hash(net, &nulladdr, port);
 142 #endif
 143         return ipv4_portaddr_hash(net, 0, port);
 144 }
 145
 146 void inet_get_local_port_range(struct net *net, int *low, int *high)
 147 {
 148         unsigned int seq;
 149
 150         do {
 151                 seq = read_seqbegin(&net->ipv4.ip_local_ports.lock);
 152
 153                 *low = net->ipv4.ip_local_ports.range[0];
 154                 *high = net->ipv4.ip_local_ports.range[1];
 155         } while (read_seqretry(&net->ipv4.ip_local_ports.lock, seq));
 156 }
 157 EXPORT_SYMBOL(inet_get_local_port_range);
 158
 159 static bool bind_conflict_exist(const struct sock *sk, struct sock *sk2,
 160                                 kuid_t sk_uid, bool relax,
 161                                 bool reuseport_cb_ok, bool reuseport_ok)
 162 {
 163         int bound_dev_if2;
 164
 165         if (sk == sk2)
 166                 return false;
 167
 168         bound_dev_if2 = READ_ONCE(sk2->sk_bound_dev_if);
 169
 170         if (!sk->sk_bound_dev_if || !bound_dev_if2 ||
 171             sk->sk_bound_dev_if == bound_dev_if2) {
 172                 if (sk->sk_reuse && sk2->sk_reuse &&
 173                     sk2->sk_state != TCP_LISTEN) {
 174                         if (!relax || (!reuseport_ok && sk->sk_reuseport &&
 175                                        sk2->sk_reuseport && reuseport_cb_ok &&
 176                                        (sk2->sk_state == TCP_TIME_WAIT ||
 177                                         uid_eq(sk_uid, sock_i_uid(sk2)))))
 178                                 return true;
 179                 } else if (!reuseport_ok || !sk->sk_reuseport ||
 180                            !sk2->sk_reuseport || !reuseport_cb_ok ||
 181                            (sk2->sk_state != TCP_TIME_WAIT &&
 182                             !uid_eq(sk_uid, sock_i_uid(sk2)))) {
 183                         return true;
 184                 }
 185         }
 186         return false;
 187 }
 188
 189 static bool check_bhash2_conflict(const struct sock *sk,
 190                                   struct inet_bind2_bucket *tb2, kuid_t sk_uid,
 191                                   bool relax, bool reuseport_cb_ok,
 192                                   bool reuseport_ok)
 193 {
 194         struct sock *sk2;
 195
 196         sk_for_each_bound_bhash2(sk2, &tb2->owners) {
 197                 if (sk->sk_family == AF_INET && ipv6_only_sock(sk2))
 198                         continue;
 199
 200                 if (bind_conflict_exist(sk, sk2, sk_uid, relax,
 201                                         reuseport_cb_ok, reuseport_ok))
 202                         return true;
 203         }
 204         return false;
 205 }
 206
 207 /* This should be called only when the corresponding inet_bind_bucket spinlock
 208  * is held
 209  */
 210 static int inet_csk_bind_conflict(const struct sock *sk, int port,
 211                                   struct inet_bind_bucket *tb,
 212                                   struct inet_bind2_bucket *tb2, /* may be null */
 213                                   bool relax, bool reuseport_ok)
 214 {
 215         struct inet_hashinfo *hinfo = sk->sk_prot->h.hashinfo;
 216         kuid_t uid = sock_i_uid((struct sock *)sk);
 217         struct sock_reuseport *reuseport_cb;
 218         struct inet_bind2_hashbucket *head2;
 219         bool reuseport_cb_ok;
 220         struct sock *sk2;
 221         struct net *net;
 222         int l3mdev;
 223         u32 hash;
 224
 225         rcu_read_lock();
 226         reuseport_cb = rcu_dereference(sk->sk_reuseport_cb);
 227         /* paired with WRITE_ONCE() in __reuseport_(add|detach)_closed_sock */
 228         reuseport_cb_ok = !reuseport_cb || READ_ONCE(reuseport_cb->num_closed_socks);
 229         rcu_read_unlock();
 230
 231         /*
 232          * Unlike other sk lookup places we do not check
 233          * for sk_net here, since _all_ the socks listed
 234          * in tb->owners and tb2->owners list belong
 235          * to the same net
 236          */
 237
 238         if (!use_bhash2_on_bind(sk)) {
 239                 sk_for_each_bound(sk2, &tb->owners)
 240                         if (bind_conflict_exist(sk, sk2, uid, relax,
 241                                                 reuseport_cb_ok, reuseport_ok) &&
 242                             inet_rcv_saddr_equal(sk, sk2, true))
 243                                 return true;
 244
 245                 return false;
 246         }
 247
 248         if (tb2 && check_bhash2_conflict(sk, tb2, uid, relax, reuseport_cb_ok,
 249                                          reuseport_ok))
 250                 return true;
 251
 252         net = sock_net(sk);
 253
 254         /* check there's no conflict with an existing IPV6_ADDR_ANY (if ipv6) or
 255          * INADDR_ANY (if ipv4) socket.
 256          */
 257         hash = get_bhash2_nulladdr_hash(sk, net, port);
 258         head2 = &hinfo->bhash2[hash & (hinfo->bhash_size - 1)];
 259
 260         l3mdev = inet_sk_bound_l3mdev(sk);
 261         inet_bind_bucket_for_each(tb2, &head2->chain)
 262                 if (check_bind2_bucket_match_nulladdr(tb2, net, port, l3mdev, sk))
 263                         break;
 264
 265         if (tb2 && check_bhash2_conflict(sk, tb2, uid, relax, reuseport_cb_ok,
 266                                          reuseport_ok))
 267                 return true;
 268
 269         return false;
 270 }
 271
 272 /*
 273  * Find an open port number for the socket.  Returns with the
 274  * inet_bind_hashbucket lock held.
 275  */
 276 static struct inet_bind_hashbucket *
 277 inet_csk_find_open_port(struct sock *sk, struct inet_bind_bucket **tb_ret,
 278                         struct inet_bind2_bucket **tb2_ret,
 279                         struct inet_bind2_hashbucket **head2_ret, int *port_ret)
 280 {
 281         struct inet_hashinfo *hinfo = sk->sk_prot->h.hashinfo;
 282         struct inet_bind2_hashbucket *head2;
 283         struct inet_bind_hashbucket *head;
 284         struct net *net = sock_net(sk);
 285         int i, low, high, attempt_half;
 286         struct inet_bind2_bucket *tb2;
 287         struct inet_bind_bucket *tb;
 288         u32 remaining, offset;
 289         bool relax = false;
 290         int port = 0;
 291         int l3mdev;
 292
 293         l3mdev = inet_sk_bound_l3mdev(sk);
 294 ports_exhausted:
 295         attempt_half = (sk->sk_reuse == SK_CAN_REUSE) ? 1 : 0;
 296 other_half_scan:
 297         inet_get_local_port_range(net, &low, &high);
 298         high++; /* [32768, 60999] -> [32768, 61000[ */
 299         if (high - low < 4)
 300                 attempt_half = 0;
 301         if (attempt_half) {
 302                 int half = low + (((high - low) >> 2) << 1);
 303
 304                 if (attempt_half == 1)
 305                         high = half;
 306                 else
 307                         low = half;
 308         }
 309         remaining = high - low;
 310         if (likely(remaining > 1))
 311                 remaining &= ~1U;
 312
 313         offset = prandom_u32() % remaining;
 314         /* __inet_hash_connect() favors ports having @low parity
 315          * We do the opposite to not pollute connect() users.
 316          */
 317         offset |= 1U;
 318
 319 other_parity_scan:
 320         port = low + offset;
 321         for (i = 0; i < remaining; i += 2, port += 2) {
 322                 if (unlikely(port >= high))
 323                         port -= remaining;
 324                 if (inet_is_local_reserved_port(net, port))
 325                         continue;
 326                 head = &hinfo->bhash[inet_bhashfn(net, port,
 327                                                   hinfo->bhash_size)];
 328                 spin_lock_bh(&head->lock);
 329                 tb2 = inet_bind2_bucket_find(hinfo, net, port, l3mdev, sk,
 330                                              &head2);
 331                 inet_bind_bucket_for_each(tb, &head->chain)
 332                         if (check_bind_bucket_match(tb, net, port, l3mdev)) {
 333                                 if (!inet_csk_bind_conflict(sk, port, tb, tb2,
 334                                                             relax, false))
 335                                         goto success;
 336                                 goto next_port;
 337                         }
 338                 tb = NULL;
 339                 goto success;
 340 next_port:
 341                 spin_unlock_bh(&head->lock);
 342                 cond_resched();
 343         }
 344
 345         offset--;
 346         if (!(offset & 1))
 347                 goto other_parity_scan;
 348
 349         if (attempt_half == 1) {
 350                 /* OK we now try the upper half of the range */
 351                 attempt_half = 2;
 352                 goto other_half_scan;
 353         }
 354
 355         if (net->ipv4.sysctl_ip_autobind_reuse && !relax) {
 356                 /* We still have a chance to connect to different destinations */
 357                 relax = true;
 358                 goto ports_exhausted;
 359         }
 360         return NULL;
 361 success:
 362         *port_ret = port;
 363         *tb_ret = tb;
 364         *tb2_ret = tb2;
 365         *head2_ret = head2;
 366         return head;
 367 }
 368
 369 static inline int sk_reuseport_match(struct inet_bind_bucket *tb,
 370                                      struct sock *sk)
 371 {
 372         kuid_t uid = sock_i_uid(sk);
 373
 374         if (tb->fastreuseport <= 0)
 375                 return 0;
 376         if (!sk->sk_reuseport)
 377                 return 0;
 378         if (rcu_access_pointer(sk->sk_reuseport_cb))
 379                 return 0;
 380         if (!uid_eq(tb->fastuid, uid))
 381                 return 0;
 382         /* We only need to check the rcv_saddr if this tb was once marked
 383          * without fastreuseport and then was reset, as we can only know that
 384          * the fast_*rcv_saddr doesn't have any conflicts with the socks on the
 385          * owners list.
 386          */
 387         if (tb->fastreuseport == FASTREUSEPORT_ANY)
 388                 return 1;
 389 #if IS_ENABLED(CONFIG_IPV6)
 390         if (tb->fast_sk_family == AF_INET6)
 391                 return ipv6_rcv_saddr_equal(&tb->fast_v6_rcv_saddr,
 392                                             inet6_rcv_saddr(sk),
 393                                             tb->fast_rcv_saddr,
 394                                             sk->sk_rcv_saddr,
 395                                             tb->fast_ipv6_only,
 396                                             ipv6_only_sock(sk), true, false);
 397 #endif
 398         return ipv4_rcv_saddr_equal(tb->fast_rcv_saddr, sk->sk_rcv_saddr,
 399                                     ipv6_only_sock(sk), true, false);
 400 }
 401
 402 void inet_csk_update_fastreuse(struct inet_bind_bucket *tb,
 403                                struct sock *sk)
 404 {
 405         kuid_t uid = sock_i_uid(sk);
 406         bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN;
 407
 408         if (hlist_empty(&tb->owners)) {
 409                 tb->fastreuse = reuse;
 410                 if (sk->sk_reuseport) {
 411                         tb->fastreuseport = FASTREUSEPORT_ANY;
 412                         tb->fastuid = uid;
 413                         tb->fast_rcv_saddr = sk->sk_rcv_saddr;
 414                         tb->fast_ipv6_only = ipv6_only_sock(sk);
 415                         tb->fast_sk_family = sk->sk_family;
 416 #if IS_ENABLED(CONFIG_IPV6)
 417                         tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
 418 #endif
 419                 } else {
 420                         tb->fastreuseport = 0;
 421                 }
 422         } else {
 423                 if (!reuse)
 424                         tb->fastreuse = 0;
 425                 if (sk->sk_reuseport) {
 426                         /* We didn't match or we don't have fastreuseport set on
 427                          * the tb, but we have sk_reuseport set on this socket
 428                          * and we know that there are no bind conflicts with
 429                          * this socket in this tb, so reset our tb's reuseport
 430                          * settings so that any subsequent sockets that match
 431                          * our current socket will be put on the fast path.
 432                          *
 433                          * If we reset we need to set FASTREUSEPORT_STRICT so we
 434                          * do extra checking for all subsequent sk_reuseport
 435                          * socks.
 436                          */
 437                         if (!sk_reuseport_match(tb, sk)) {
 438                                 tb->fastreuseport = FASTREUSEPORT_STRICT;
 439                                 tb->fastuid = uid;
 440                                 tb->fast_rcv_saddr = sk->sk_rcv_saddr;
 441                                 tb->fast_ipv6_only = ipv6_only_sock(sk);
 442                                 tb->fast_sk_family = sk->sk_family;
 443 #if IS_ENABLED(CONFIG_IPV6)
 444                                 tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
 445 #endif
 446                         }
 447                 } else {
 448                         tb->fastreuseport = 0;
 449                 }
 450         }
 451 }
 452
 453 /* Obtain a reference to a local port for the given sock,
 454  * if snum is zero it means select any available local port.
 455  * We try to allocate an odd port (and leave even ports for connect())
 456  */
 457 int inet_csk_get_port(struct sock *sk, unsigned short snum)
 458 {
 459         bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN;
 460         struct inet_hashinfo *hinfo = sk->sk_prot->h.hashinfo;
 461         bool bhash_created = false, bhash2_created = false;
 462         struct inet_bind2_bucket *tb2 = NULL;
 463         struct inet_bind2_hashbucket *head2;
 464         struct inet_bind_bucket *tb = NULL;
 465         struct inet_bind_hashbucket *head;
 466         struct net *net = sock_net(sk);
 467         int ret = 1, port = snum;
 468         bool found_port = false;
 469         int l3mdev;
 470
 471         l3mdev = inet_sk_bound_l3mdev(sk);
 472
 473         if (!port) {
 474                 head = inet_csk_find_open_port(sk, &tb, &tb2, &head2, &port);
 475                 if (!head)
 476                         return ret;
 477                 if (tb && tb2)
 478                         goto success;
 479                 found_port = true;
 480         } else {
 481                 head = &hinfo->bhash[inet_bhashfn(net, port,
 482                                                   hinfo->bhash_size)];
 483                 spin_lock_bh(&head->lock);
 484                 inet_bind_bucket_for_each(tb, &head->chain)
 485                         if (check_bind_bucket_match(tb, net, port, l3mdev))
 486                                 break;
 487
 488                 tb2 = inet_bind2_bucket_find(hinfo, net, port, l3mdev, sk,
 489                                              &head2);
 490         }
 491
 492         if (!tb) {
 493                 tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep, net,
 494                                              head, port, l3mdev);
 495                 if (!tb)
 496                         goto fail_unlock;
 497                 bhash_created = true;
 498         }
 499
 500         if (!tb2) {
 501                 tb2 = inet_bind2_bucket_create(hinfo->bind2_bucket_cachep,
 502                                                net, head2, port, l3mdev, sk);
 503                 if (!tb2)
 504                         goto fail_unlock;
 505                 bhash2_created = true;
 506         }
 507
 508         /* If we had to find an open port, we already checked for conflicts */
 509         if (!found_port && !hlist_empty(&tb->owners)) {
 510                 if (sk->sk_reuse == SK_FORCE_REUSE)
 511                         goto success;
 512
 513                 if ((tb->fastreuse > 0 && reuse) ||
 514                     sk_reuseport_match(tb, sk))
 515                         goto success;
 516                 if (inet_csk_bind_conflict(sk, port, tb, tb2, true, true))
 517                         goto fail_unlock;
 518         }
 519 success:
 520         inet_csk_update_fastreuse(tb, sk);
 521
 522         if (!inet_csk(sk)->icsk_bind_hash)
 523                 inet_bind_hash(sk, tb, tb2, port);
 524         WARN_ON(inet_csk(sk)->icsk_bind_hash != tb);
 525         WARN_ON(inet_csk(sk)->icsk_bind2_hash != tb2);
 526         ret = 0;
 527
 528 fail_unlock:
 529         if (ret) {
 530                 if (bhash_created)
 531                         inet_bind_bucket_destroy(hinfo->bind_bucket_cachep, tb);
 532                 if (bhash2_created)
 533                         inet_bind2_bucket_destroy(hinfo->bind2_bucket_cachep,
 534                                                   tb2);
 535         }
 536         spin_unlock_bh(&head->lock);
 537         return ret;
 538 }
 539 EXPORT_SYMBOL_GPL(inet_csk_get_port);
 540
 541 /*
 542  * Wait for an incoming connection, avoid race conditions. This must be called
 543  * with the socket locked.
 544  */
 545 static int inet_csk_wait_for_connect(struct sock *sk, long timeo)
 546 {
 547         struct inet_connection_sock *icsk = inet_csk(sk);
 548         DEFINE_WAIT(wait);
 549         int err;
 550
 551         /*
 552          * True wake-one mechanism for incoming connections: only
 553          * one process gets woken up, not the 'whole herd'.
 554          * Since we do not 'race & poll' for established sockets
 555          * anymore, the common case will execute the loop only once.
 556          *
 557          * Subtle issue: "add_wait_queue_exclusive()" will be added
 558          * after any current non-exclusive waiters, and we know that
 559          * it will always _stay_ after any new non-exclusive waiters
 560          * because all non-exclusive waiters are added at the
 561          * beginning of the wait-queue. As such, it's ok to "drop"
 562          * our exclusiveness temporarily when we get woken up without
 563          * having to remove and re-insert us on the wait queue.
 564          */
 565         for (;;) {
 566                 prepare_to_wait_exclusive(sk_sleep(sk), &wait,
 567                                           TASK_INTERRUPTIBLE);
 568                 release_sock(sk);
 569                 if (reqsk_queue_empty(&icsk->icsk_accept_queue))
 570                         timeo = schedule_timeout(timeo);
 571                 sched_annotate_sleep();
 572                 lock_sock(sk);
 573                 err = 0;
 574                 if (!reqsk_queue_empty(&icsk->icsk_accept_queue))
 575                         break;
 576                 err = -EINVAL;
 577                 if (sk->sk_state != TCP_LISTEN)
 578                         break;
 579                 err = sock_intr_errno(timeo);
 580                 if (signal_pending(current))
 581                         break;
 582                 err = -EAGAIN;
 583                 if (!timeo)
 584                         break;
 585         }
 586         finish_wait(sk_sleep(sk), &wait);
 587         return err;
 588 }
 589
 590 /*
 591  * This will accept the next outstanding connection.
 592  */
 593 struct sock *inet_csk_accept(struct sock *sk, int flags, int *err, bool kern)
 594 {
 595         struct inet_connection_sock *icsk = inet_csk(sk);
 596         struct request_sock_queue *queue = &icsk->icsk_accept_queue;
 597         struct request_sock *req;
 598         struct sock *newsk;
 599         int error;
 600
 601         lock_sock(sk);
 602
 603         /* We need to make sure that this socket is listening,
 604          * and that it has something pending.
 605          */
 606         error = -EINVAL;
 607         if (sk->sk_state != TCP_LISTEN)
 608                 goto out_err;
 609
 610         /* Find already established connection */
 611         if (reqsk_queue_empty(queue)) {
 612                 long timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);
 613
 614                 /* If this is a non blocking socket don't sleep */
 615                 error = -EAGAIN;
 616                 if (!timeo)
 617                         goto out_err;
 618
 619                 error = inet_csk_wait_for_connect(sk, timeo);
 620                 if (error)
 621                         goto out_err;
 622         }
 623         req = reqsk_queue_remove(queue, sk);
 624         newsk = req->sk;
 625
 626         if (sk->sk_protocol == IPPROTO_TCP &&
 627             tcp_rsk(req)->tfo_listener) {
 628                 spin_lock_bh(&queue->fastopenq.lock);
 629                 if (tcp_rsk(req)->tfo_listener) {
 630                         /* We are still waiting for the final ACK from 3WHS
 631                          * so can't free req now. Instead, we set req->sk to
 632                          * NULL to signify that the child socket is taken
 633                          * so reqsk_fastopen_remove() will free the req
 634                          * when 3WHS finishes (or is aborted).
 635                          */
 636                         req->sk = NULL;
 637                         req = NULL;
 638                 }
 639                 spin_unlock_bh(&queue->fastopenq.lock);
 640         }
 641
 642 out:
 643         release_sock(sk);
 644         if (newsk && mem_cgroup_sockets_enabled) {
 645                 int amt;
 646
 647                 /* atomically get the memory usage, set and charge the
 648                  * newsk->sk_memcg.
 649                  */
 650                 lock_sock(newsk);
 651
 652                 /* The socket has not been accepted yet, no need to look at
 653                  * newsk->sk_wmem_queued.
 654                  */
 655                 amt = sk_mem_pages(newsk->sk_forward_alloc +
 656                                    atomic_read(&newsk->sk_rmem_alloc));
 657                 mem_cgroup_sk_alloc(newsk);
 658                 if (newsk->sk_memcg && amt)
 659                         mem_cgroup_charge_skmem(newsk->sk_memcg, amt,
 660                                                 GFP_KERNEL | __GFP_NOFAIL);
 661
 662                 release_sock(newsk);
 663         }
 664         if (req)
 665                 reqsk_put(req);
 666         return newsk;
 667 out_err:
 668         newsk = NULL;
 669         req = NULL;
 670         *err = error;
 671         goto out;
 672 }
 673 EXPORT_SYMBOL(inet_csk_accept);
 674
 675 /*
 676  * Using different timers for retransmit, delayed acks and probes
 677  * We may wish use just one timer maintaining a list of expire jiffies
 678  * to optimize.
 679  */
 680 void inet_csk_init_xmit_timers(struct sock *sk,
 681                                void (*retransmit_handler)(struct timer_list *t),
 682                                void (*delack_handler)(struct timer_list *t),
 683                                void (*keepalive_handler)(struct timer_list *t))
 684 {
 685         struct inet_connection_sock *icsk = inet_csk(sk);
 686
 687         timer_setup(&icsk->icsk_retransmit_timer, retransmit_handler, 0);
 688         timer_setup(&icsk->icsk_delack_timer, delack_handler, 0);
 689         timer_setup(&sk->sk_timer, keepalive_handler, 0);
 690         icsk->icsk_pending = icsk->icsk_ack.pending = 0;
 691 }
 692 EXPORT_SYMBOL(inet_csk_init_xmit_timers);
 693
 694 void inet_csk_clear_xmit_timers(struct sock *sk)
 695 {
 696         struct inet_connection_sock *icsk = inet_csk(sk);
 697
 698         icsk->icsk_pending = icsk->icsk_ack.pending = 0;
 699
 700         sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
 701         sk_stop_timer(sk, &icsk->icsk_delack_timer);
 702         sk_stop_timer(sk, &sk->sk_timer);
 703 }
 704 EXPORT_SYMBOL(inet_csk_clear_xmit_timers);
 705
 706 void inet_csk_delete_keepalive_timer(struct sock *sk)
 707 {
 708         sk_stop_timer(sk, &sk->sk_timer);
 709 }
 710 EXPORT_SYMBOL(inet_csk_delete_keepalive_timer);
 711
 712 void inet_csk_reset_keepalive_timer(struct sock *sk, unsigned long len)
 713 {
 714         sk_reset_timer(sk, &sk->sk_timer, jiffies + len);
 715 }
 716 EXPORT_SYMBOL(inet_csk_reset_keepalive_timer);
 717
 718 struct dst_entry *inet_csk_route_req(const struct sock *sk,
 719                                      struct flowi4 *fl4,
 720                                      const struct request_sock *req)
 721 {
 722         const struct inet_request_sock *ireq = inet_rsk(req);
 723         struct net *net = read_pnet(&ireq->ireq_net);
 724         struct ip_options_rcu *opt;
 725         struct rtable *rt;
 726
 727         rcu_read_lock();
 728         opt = rcu_dereference(ireq->ireq_opt);
 729
 730         flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
 731                            RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
 732                            sk->sk_protocol, inet_sk_flowi_flags(sk),
 733                            (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
 734                            ireq->ir_loc_addr, ireq->ir_rmt_port,
 735                            htons(ireq->ir_num), sk->sk_uid);
 736         security_req_classify_flow(req, flowi4_to_flowi_common(fl4));
 737         rt = ip_route_output_flow(net, fl4, sk);
 738         if (IS_ERR(rt))
 739                 goto no_route;
 740         if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
 741                 goto route_err;
 742         rcu_read_unlock();
 743         return &rt->dst;
 744
 745 route_err:
 746         ip_rt_put(rt);
 747 no_route:
 748         rcu_read_unlock();
 749         __IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
 750         return NULL;
 751 }
 752 EXPORT_SYMBOL_GPL(inet_csk_route_req);
 753
 754 struct dst_entry *inet_csk_route_child_sock(const struct sock *sk,
 755                                             struct sock *newsk,
 756                                             const struct request_sock *req)
 757 {
 758         const struct inet_request_sock *ireq = inet_rsk(req);
 759         struct net *net = read_pnet(&ireq->ireq_net);
 760         struct inet_sock *newinet = inet_sk(newsk);
 761         struct ip_options_rcu *opt;
 762         struct flowi4 *fl4;
 763         struct rtable *rt;
 764
 765         opt = rcu_dereference(ireq->ireq_opt);
 766         fl4 = &newinet->cork.fl.u.ip4;
 767
 768         flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
 769                            RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
 770                            sk->sk_protocol, inet_sk_flowi_flags(sk),
 771                            (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
 772                            ireq->ir_loc_addr, ireq->ir_rmt_port,
 773                            htons(ireq->ir_num), sk->sk_uid);
 774         security_req_classify_flow(req, flowi4_to_flowi_common(fl4));
 775         rt = ip_route_output_flow(net, fl4, sk);
 776         if (IS_ERR(rt))
 777                 goto no_route;
 778         if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
 779                 goto route_err;
 780         return &rt->dst;
 781
 782 route_err:
 783         ip_rt_put(rt);
 784 no_route:
 785         __IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
 786         return NULL;
 787 }
 788 EXPORT_SYMBOL_GPL(inet_csk_route_child_sock);
 789
 790 /* Decide when to expire the request and when to resend SYN-ACK */
 791 static void syn_ack_recalc(struct request_sock *req,
 792                            const int max_syn_ack_retries,
 793                            const u8 rskq_defer_accept,
 794                            int *expire, int *resend)
 795 {
 796         if (!rskq_defer_accept) {
 797                 *expire = req->num_timeout >= max_syn_ack_retries;
 798                 *resend = 1;
 799                 return;
 800         }
 801         *expire = req->num_timeout >= max_syn_ack_retries &&
 802                   (!inet_rsk(req)->acked || req->num_timeout >= rskq_defer_accept);
 803         /* Do not resend while waiting for data after ACK,
 804          * start to resend on end of deferring period to give
 805          * last chance for data or ACK to create established socket.
 806          */
 807         *resend = !inet_rsk(req)->acked ||
 808                   req->num_timeout >= rskq_defer_accept - 1;
 809 }
 810
 811 int inet_rtx_syn_ack(const struct sock *parent, struct request_sock *req)
 812 {
 813         int err = req->rsk_ops->rtx_syn_ack(parent, req);
 814
 815         if (!err)
 816                 req->num_retrans++;
 817         return err;
 818 }
 819 EXPORT_SYMBOL(inet_rtx_syn_ack);
 820
 821 static struct request_sock *inet_reqsk_clone(struct request_sock *req,
 822                                              struct sock *sk)
 823 {
 824         struct sock *req_sk, *nreq_sk;
 825         struct request_sock *nreq;
 826
 827         nreq = kmem_cache_alloc(req->rsk_ops->slab, GFP_ATOMIC | __GFP_NOWARN);
 828         if (!nreq) {
 829                 __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQFAILURE);
 830
 831                 /* paired with refcount_inc_not_zero() in reuseport_migrate_sock() */
 832                 sock_put(sk);
 833                 return NULL;
 834         }
 835
 836         req_sk = req_to_sk(req);
 837         nreq_sk = req_to_sk(nreq);
 838
 839         memcpy(nreq_sk, req_sk,
 840                offsetof(struct sock, sk_dontcopy_begin));
 841         memcpy(&nreq_sk->sk_dontcopy_end, &req_sk->sk_dontcopy_end,
 842                req->rsk_ops->obj_size - offsetof(struct sock, sk_dontcopy_end));
 843
 844         sk_node_init(&nreq_sk->sk_node);
 845         nreq_sk->sk_tx_queue_mapping = req_sk->sk_tx_queue_mapping;
 846 #ifdef CONFIG_SOCK_RX_QUEUE_MAPPING
 847         nreq_sk->sk_rx_queue_mapping = req_sk->sk_rx_queue_mapping;
 848 #endif
 849         nreq_sk->sk_incoming_cpu = req_sk->sk_incoming_cpu;
 850
 851         nreq->rsk_listener = sk;
 852
 853         /* We need not acquire fastopenq->lock
 854          * because the child socket is locked in inet_csk_listen_stop().
 855          */
 856         if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(nreq)->tfo_listener)
 857                 rcu_assign_pointer(tcp_sk(nreq->sk)->fastopen_rsk, nreq);
 858
 859         return nreq;
 860 }
 861
 862 static void reqsk_queue_migrated(struct request_sock_queue *queue,
 863                                  const struct request_sock *req)
 864 {
 865         if (req->num_timeout == 0)
 866                 atomic_inc(&queue->young);
 867         atomic_inc(&queue->qlen);
 868 }
 869
 870 static void reqsk_migrate_reset(struct request_sock *req)
 871 {
 872         req->saved_syn = NULL;
 873 #if IS_ENABLED(CONFIG_IPV6)
 874         inet_rsk(req)->ipv6_opt = NULL;
 875         inet_rsk(req)->pktopts = NULL;
 876 #else
 877         inet_rsk(req)->ireq_opt = NULL;
 878 #endif
 879 }
 880
 881 /* return true if req was found in the ehash table */
 882 static bool reqsk_queue_unlink(struct request_sock *req)
 883 {
 884         struct inet_hashinfo *hashinfo = req_to_sk(req)->sk_prot->h.hashinfo;
 885         bool found = false;
 886
 887         if (sk_hashed(req_to_sk(req))) {
 888                 spinlock_t *lock = inet_ehash_lockp(hashinfo, req->rsk_hash);
 889
 890                 spin_lock(lock);
 891                 found = __sk_nulls_del_node_init_rcu(req_to_sk(req));
 892                 spin_unlock(lock);
 893         }
 894         if (timer_pending(&req->rsk_timer) && del_timer_sync(&req->rsk_timer))
 895                 reqsk_put(req);
 896         return found;
 897 }
 898
 899 bool inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req)
 900 {
 901         bool unlinked = reqsk_queue_unlink(req);
 902
 903         if (unlinked) {
 904                 reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req);
 905                 reqsk_put(req);
 906         }
 907         return unlinked;
 908 }
 909 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop);
 910
 911 void inet_csk_reqsk_queue_drop_and_put(struct sock *sk, struct request_sock *req)
 912 {
 913         inet_csk_reqsk_queue_drop(sk, req);
 914         reqsk_put(req);
 915 }
 916 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop_and_put);
 917
 918 static void reqsk_timer_handler(struct timer_list *t)
 919 {
 920         struct request_sock *req = from_timer(req, t, rsk_timer);
 921         struct request_sock *nreq = NULL, *oreq = req;
 922         struct sock *sk_listener = req->rsk_listener;
 923         struct inet_connection_sock *icsk;
 924         struct request_sock_queue *queue;
 925         struct net *net;
 926         int max_syn_ack_retries, qlen, expire = 0, resend = 0;
 927
 928         if (inet_sk_state_load(sk_listener) != TCP_LISTEN) {
 929                 struct sock *nsk;
 930
 931                 nsk = reuseport_migrate_sock(sk_listener, req_to_sk(req), NULL);
 932                 if (!nsk)
 933                         goto drop;
 934
 935                 nreq = inet_reqsk_clone(req, nsk);
 936                 if (!nreq)
 937                         goto drop;
 938
 939                 /* The new timer for the cloned req can decrease the 2
 940                  * by calling inet_csk_reqsk_queue_drop_and_put(), so
 941                  * hold another count to prevent use-after-free and
 942                  * call reqsk_put() just before return.
 943                  */
 944                 refcount_set(&nreq->rsk_refcnt, 2 + 1);
 945                 timer_setup(&nreq->rsk_timer, reqsk_timer_handler, TIMER_PINNED);
 946                 reqsk_queue_migrated(&inet_csk(nsk)->icsk_accept_queue, req);
 947
 948                 req = nreq;
 949                 sk_listener = nsk;
 950         }
 951
 952         icsk = inet_csk(sk_listener);
 953         net = sock_net(sk_listener);
 954         max_syn_ack_retries = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_synack_retries;
 955         /* Normally all the openreqs are young and become mature
 956          * (i.e. converted to established socket) for first timeout.
 957          * If synack was not acknowledged for 1 second, it means
 958          * one of the following things: synack was lost, ack was lost,
 959          * rtt is high or nobody planned to ack (i.e. synflood).
 960          * When server is a bit loaded, queue is populated with old
 961          * open requests, reducing effective size of queue.
 962          * When server is well loaded, queue size reduces to zero
 963          * after several minutes of work. It is not synflood,
 964          * it is normal operation. The solution is pruning
 965          * too old entries overriding normal timeout, when
 966          * situation becomes dangerous.
 967          *
 968          * Essentially, we reserve half of room for young
 969          * embrions; and abort old ones without pity, if old
 970          * ones are about to clog our table.
 971          */
 972         queue = &icsk->icsk_accept_queue;
 973         qlen = reqsk_queue_len(queue);
 974         if ((qlen << 1) > max(8U, READ_ONCE(sk_listener->sk_max_ack_backlog))) {
 975                 int young = reqsk_queue_len_young(queue) << 1;
 976
 977                 while (max_syn_ack_retries > 2) {
 978                         if (qlen < young)
 979                                 break;
 980                         max_syn_ack_retries--;
 981                         young <<= 1;
 982                 }
 983         }
 984         syn_ack_recalc(req, max_syn_ack_retries, READ_ONCE(queue->rskq_defer_accept),
 985                        &expire, &resend);
 986         req->rsk_ops->syn_ack_timeout(req);
 987         if (!expire &&
 988             (!resend ||
 989              !inet_rtx_syn_ack(sk_listener, req) ||
 990              inet_rsk(req)->acked)) {
 991                 if (req->num_timeout++ == 0)
 992                         atomic_dec(&queue->young);
 993                 mod_timer(&req->rsk_timer, jiffies + reqsk_timeout(req, TCP_RTO_MAX));
 994
 995                 if (!nreq)
 996                         return;
 997
 998                 if (!inet_ehash_insert(req_to_sk(nreq), req_to_sk(oreq), NULL)) {
 999                         /* delete timer */
1000                         inet_csk_reqsk_queue_drop(sk_listener, nreq);
1001                         goto no_ownership;
1002                 }
1003
1004                 __NET_INC_STATS(net, LINUX_MIB_TCPMIGRATEREQSUCCESS);
1005                 reqsk_migrate_reset(oreq);
1006                 reqsk_queue_removed(&inet_csk(oreq->rsk_listener)->icsk_accept_queue, oreq);
1007                 reqsk_put(oreq);
1008
1009                 reqsk_put(nreq);
1010                 return;
1011         }
1012
1013         /* Even if we can clone the req, we may need not retransmit any more
1014          * SYN+ACKs (nreq->num_timeout > max_syn_ack_retries, etc), or another
1015          * CPU may win the "own_req" race so that inet_ehash_insert() fails.
1016          */
1017         if (nreq) {
1018                 __NET_INC_STATS(net, LINUX_MIB_TCPMIGRATEREQFAILURE);
1019 no_ownership:
1020                 reqsk_migrate_reset(nreq);
1021                 reqsk_queue_removed(queue, nreq);
1022                 __reqsk_free(nreq);
1023         }
1024
1025 drop:
1026         inet_csk_reqsk_queue_drop_and_put(oreq->rsk_listener, oreq);
1027 }
1028
1029 static void reqsk_queue_hash_req(struct request_sock *req,
1030                                  unsigned long timeout)
1031 {
1032         timer_setup(&req->rsk_timer, reqsk_timer_handler, TIMER_PINNED);
1033         mod_timer(&req->rsk_timer, jiffies + timeout);
1034
1035         inet_ehash_insert(req_to_sk(req), NULL, NULL);
1036         /* before letting lookups find us, make sure all req fields
1037          * are committed to memory and refcnt initialized.
1038          */
1039         smp_wmb();
1040         refcount_set(&req->rsk_refcnt, 2 + 1);
1041 }
1042
1043 void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
1044                                    unsigned long timeout)
1045 {
1046         reqsk_queue_hash_req(req, timeout);
1047         inet_csk_reqsk_queue_added(sk);
1048 }
1049 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add);
1050
1051 static void inet_clone_ulp(const struct request_sock *req, struct sock *newsk,
1052                            const gfp_t priority)
1053 {
1054         struct inet_connection_sock *icsk = inet_csk(newsk);
1055
1056         if (!icsk->icsk_ulp_ops)
1057                 return;
1058
1059         if (icsk->icsk_ulp_ops->clone)
1060                 icsk->icsk_ulp_ops->clone(req, newsk, priority);
1061 }
1062
1063 /**
1064  *      inet_csk_clone_lock - clone an inet socket, and lock its clone
1065  *      @sk: the socket to clone
1066  *      @req: request_sock
1067  *      @priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc)
1068  *
1069  *      Caller must unlock socket even in error path (bh_unlock_sock(newsk))
1070  */
1071 struct sock *inet_csk_clone_lock(const struct sock *sk,
1072                                  const struct request_sock *req,
1073                                  const gfp_t priority)
1074 {
1075         struct sock *newsk = sk_clone_lock(sk, priority);
1076
1077         if (newsk) {
1078                 struct inet_connection_sock *newicsk = inet_csk(newsk);
1079
1080                 inet_sk_set_state(newsk, TCP_SYN_RECV);
1081                 newicsk->icsk_bind_hash = NULL;
1082                 newicsk->icsk_bind2_hash = NULL;
1083
1084                 inet_sk(newsk)->inet_dport = inet_rsk(req)->ir_rmt_port;
1085                 inet_sk(newsk)->inet_num = inet_rsk(req)->ir_num;
1086                 inet_sk(newsk)->inet_sport = htons(inet_rsk(req)->ir_num);
1087
1088                 /* listeners have SOCK_RCU_FREE, not the children */
1089                 sock_reset_flag(newsk, SOCK_RCU_FREE);
1090
1091                 inet_sk(newsk)->mc_list = NULL;
1092
1093                 newsk->sk_mark = inet_rsk(req)->ir_mark;
1094                 atomic64_set(&newsk->sk_cookie,
1095                              atomic64_read(&inet_rsk(req)->ir_cookie));
1096
1097                 newicsk->icsk_retransmits = 0;
1098                 newicsk->icsk_backoff     = 0;
1099                 newicsk->icsk_probes_out  = 0;
1100                 newicsk->icsk_probes_tstamp = 0;
1101
1102                 /* Deinitialize accept_queue to trap illegal accesses. */
1103                 memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue));
1104
1105                 inet_clone_ulp(req, newsk, priority);
1106
1107                 security_inet_csk_clone(newsk, req);
1108         }
1109         return newsk;
1110 }
1111 EXPORT_SYMBOL_GPL(inet_csk_clone_lock);
1112
1113 /*
1114  * At this point, there should be no process reference to this
1115  * socket, and thus no user references at all.  Therefore we
1116  * can assume the socket waitqueue is inactive and nobody will
1117  * try to jump onto it.
1118  */
1119 void inet_csk_destroy_sock(struct sock *sk)
1120 {
1121         WARN_ON(sk->sk_state != TCP_CLOSE);
1122         WARN_ON(!sock_flag(sk, SOCK_DEAD));
1123
1124         /* It cannot be in hash table! */
1125         WARN_ON(!sk_unhashed(sk));
1126
1127         /* If it has not 0 inet_sk(sk)->inet_num, it must be bound */
1128         WARN_ON(inet_sk(sk)->inet_num && !inet_csk(sk)->icsk_bind_hash);
1129
1130         sk->sk_prot->destroy(sk);
1131
1132         sk_stream_kill_queues(sk);
1133
1134         xfrm_sk_free_policy(sk);
1135
1136         sk_refcnt_debug_release(sk);
1137
1138         this_cpu_dec(*sk->sk_prot->orphan_count);
1139
1140         sock_put(sk);
1141 }
1142 EXPORT_SYMBOL(inet_csk_destroy_sock);
1143
1144 /* This function allows to force a closure of a socket after the call to
1145  * tcp/dccp_create_openreq_child().
1146  */
1147 void inet_csk_prepare_forced_close(struct sock *sk)
1148         __releases(&sk->sk_lock.slock)
1149 {
1150         /* sk_clone_lock locked the socket and set refcnt to 2 */
1151         bh_unlock_sock(sk);
1152         sock_put(sk);
1153         inet_csk_prepare_for_destroy_sock(sk);
1154         inet_sk(sk)->inet_num = 0;
1155 }
1156 EXPORT_SYMBOL(inet_csk_prepare_forced_close);
1157
1158 int inet_csk_listen_start(struct sock *sk)
1159 {
1160         struct inet_connection_sock *icsk = inet_csk(sk);
1161         struct inet_sock *inet = inet_sk(sk);
1162         int err = -EADDRINUSE;
1163
1164         reqsk_queue_alloc(&icsk->icsk_accept_queue);
1165
1166         sk->sk_ack_backlog = 0;
1167         inet_csk_delack_init(sk);
1168
1169         if (sk->sk_txrehash == SOCK_TXREHASH_DEFAULT)
1170                 sk->sk_txrehash = READ_ONCE(sock_net(sk)->core.sysctl_txrehash);
1171
1172         /* There is race window here: we announce ourselves listening,
1173          * but this transition is still not validated by get_port().
1174          * It is OK, because this socket enters to hash table only
1175          * after validation is complete.
1176          */
1177         inet_sk_state_store(sk, TCP_LISTEN);
1178         if (!sk->sk_prot->get_port(sk, inet->inet_num)) {
1179                 inet->inet_sport = htons(inet->inet_num);
1180
1181                 sk_dst_reset(sk);
1182                 err = sk->sk_prot->hash(sk);
1183
1184                 if (likely(!err))
1185                         return 0;
1186         }
1187
1188         inet_sk_set_state(sk, TCP_CLOSE);
1189         return err;
1190 }
1191 EXPORT_SYMBOL_GPL(inet_csk_listen_start);
1192
1193 static void inet_child_forget(struct sock *sk, struct request_sock *req,
1194                               struct sock *child)
1195 {
1196         sk->sk_prot->disconnect(child, O_NONBLOCK);
1197
1198         sock_orphan(child);
1199
1200         this_cpu_inc(*sk->sk_prot->orphan_count);
1201
1202         if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(req)->tfo_listener) {
1203                 BUG_ON(rcu_access_pointer(tcp_sk(child)->fastopen_rsk) != req);
1204                 BUG_ON(sk != req->rsk_listener);
1205
1206                 /* Paranoid, to prevent race condition if
1207                  * an inbound pkt destined for child is
1208                  * blocked by sock lock in tcp_v4_rcv().
1209                  * Also to satisfy an assertion in
1210                  * tcp_v4_destroy_sock().
1211                  */
1212                 RCU_INIT_POINTER(tcp_sk(child)->fastopen_rsk, NULL);
1213         }
1214         inet_csk_destroy_sock(child);
1215 }
1216
1217 struct sock *inet_csk_reqsk_queue_add(struct sock *sk,
1218                                       struct request_sock *req,
1219                                       struct sock *child)
1220 {
1221         struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
1222
1223         spin_lock(&queue->rskq_lock);
1224         if (unlikely(sk->sk_state != TCP_LISTEN)) {
1225                 inet_child_forget(sk, req, child);
1226                 child = NULL;
1227         } else {
1228                 req->sk = child;
1229                 req->dl_next = NULL;
1230                 if (queue->rskq_accept_head == NULL)
1231                         WRITE_ONCE(queue->rskq_accept_head, req);
1232                 else
1233                         queue->rskq_accept_tail->dl_next = req;
1234                 queue->rskq_accept_tail = req;
1235                 sk_acceptq_added(sk);
1236         }
1237         spin_unlock(&queue->rskq_lock);
1238         return child;
1239 }
1240 EXPORT_SYMBOL(inet_csk_reqsk_queue_add);
1241
1242 struct sock *inet_csk_complete_hashdance(struct sock *sk, struct sock *child,
1243                                          struct request_sock *req, bool own_req)
1244 {
1245         if (own_req) {
1246                 inet_csk_reqsk_queue_drop(req->rsk_listener, req);
1247                 reqsk_queue_removed(&inet_csk(req->rsk_listener)->icsk_accept_queue, req);
1248
1249                 if (sk != req->rsk_listener) {
1250                         /* another listening sk has been selected,
1251                          * migrate the req to it.
1252                          */
1253                         struct request_sock *nreq;
1254
1255                         /* hold a refcnt for the nreq->rsk_listener
1256                          * which is assigned in inet_reqsk_clone()
1257                          */
1258                         sock_hold(sk);
1259                         nreq = inet_reqsk_clone(req, sk);
1260                         if (!nreq) {
1261                                 inet_child_forget(sk, req, child);
1262                                 goto child_put;
1263                         }
1264
1265                         refcount_set(&nreq->rsk_refcnt, 1);
1266                         if (inet_csk_reqsk_queue_add(sk, nreq, child)) {
1267                                 __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQSUCCESS);
1268                                 reqsk_migrate_reset(req);
1269                                 reqsk_put(req);
1270                                 return child;
1271                         }
1272
1273                         __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQFAILURE);
1274                         reqsk_migrate_reset(nreq);
1275                         __reqsk_free(nreq);
1276                 } else if (inet_csk_reqsk_queue_add(sk, req, child)) {
1277                         return child;
1278                 }
1279         }
1280         /* Too bad, another child took ownership of the request, undo. */
1281 child_put:
1282         bh_unlock_sock(child);
1283         sock_put(child);
1284         return NULL;
1285 }
1286 EXPORT_SYMBOL(inet_csk_complete_hashdance);
1287
1288 /*
1289  *      This routine closes sockets which have been at least partially
1290  *      opened, but not yet accepted.
1291  */
1292 void inet_csk_listen_stop(struct sock *sk)
1293 {
1294         struct inet_connection_sock *icsk = inet_csk(sk);
1295         struct request_sock_queue *queue = &icsk->icsk_accept_queue;
1296         struct request_sock *next, *req;
1297
1298         /* Following specs, it would be better either to send FIN
1299          * (and enter FIN-WAIT-1, it is normal close)
1300          * or to send active reset (abort).
1301          * Certainly, it is pretty dangerous while synflood, but it is
1302          * bad justification for our negligence 8)
1303          * To be honest, we are not able to make either
1304          * of the variants now.                 --ANK
1305          */
1306         while ((req = reqsk_queue_remove(queue, sk)) != NULL) {
1307                 struct sock *child = req->sk, *nsk;
1308                 struct request_sock *nreq;
1309
1310                 local_bh_disable();
1311                 bh_lock_sock(child);
1312                 WARN_ON(sock_owned_by_user(child));
1313                 sock_hold(child);
1314
1315                 nsk = reuseport_migrate_sock(sk, child, NULL);
1316                 if (nsk) {
1317                         nreq = inet_reqsk_clone(req, nsk);
1318                         if (nreq) {
1319                                 refcount_set(&nreq->rsk_refcnt, 1);
1320
1321                                 if (inet_csk_reqsk_queue_add(nsk, nreq, child)) {
1322                                         __NET_INC_STATS(sock_net(nsk),
1323                                                         LINUX_MIB_TCPMIGRATEREQSUCCESS);
1324                                         reqsk_migrate_reset(req);
1325                                 } else {
1326                                         __NET_INC_STATS(sock_net(nsk),
1327                                                         LINUX_MIB_TCPMIGRATEREQFAILURE);
1328                                         reqsk_migrate_reset(nreq);
1329                                         __reqsk_free(nreq);
1330                                 }
1331
1332                                 /* inet_csk_reqsk_queue_add() has already
1333                                  * called inet_child_forget() on failure case.
1334                                  */
1335                                 goto skip_child_forget;
1336                         }
1337                 }
1338
1339                 inet_child_forget(sk, req, child);
1340 skip_child_forget:
1341                 reqsk_put(req);
1342                 bh_unlock_sock(child);
1343                 local_bh_enable();
1344                 sock_put(child);
1345
1346                 cond_resched();
1347         }
1348         if (queue->fastopenq.rskq_rst_head) {
1349                 /* Free all the reqs queued in rskq_rst_head. */
1350                 spin_lock_bh(&queue->fastopenq.lock);
1351                 req = queue->fastopenq.rskq_rst_head;
1352                 queue->fastopenq.rskq_rst_head = NULL;
1353                 spin_unlock_bh(&queue->fastopenq.lock);
1354                 while (req != NULL) {
1355                         next = req->dl_next;
1356                         reqsk_put(req);
1357                         req = next;
1358                 }
1359         }
1360         WARN_ON_ONCE(sk->sk_ack_backlog);
1361 }
1362 EXPORT_SYMBOL_GPL(inet_csk_listen_stop);
1363
1364 void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr)
1365 {
1366         struct sockaddr_in *sin = (struct sockaddr_in *)uaddr;
1367         const struct inet_sock *inet = inet_sk(sk);
1368
1369         sin->sin_family         = AF_INET;
1370         sin->sin_addr.s_addr    = inet->inet_daddr;
1371         sin->sin_port           = inet->inet_dport;
1372 }
1373 EXPORT_SYMBOL_GPL(inet_csk_addr2sockaddr);
1374
1375 static struct dst_entry *inet_csk_rebuild_route(struct sock *sk, struct flowi *fl)
1376 {
1377         const struct inet_sock *inet = inet_sk(sk);
1378         const struct ip_options_rcu *inet_opt;
1379         __be32 daddr = inet->inet_daddr;
1380         struct flowi4 *fl4;
1381         struct rtable *rt;
1382
1383         rcu_read_lock();
1384         inet_opt = rcu_dereference(inet->inet_opt);
1385         if (inet_opt && inet_opt->opt.srr)
1386                 daddr = inet_opt->opt.faddr;
1387         fl4 = &fl->u.ip4;
1388         rt = ip_route_output_ports(sock_net(sk), fl4, sk, daddr,
1389                                    inet->inet_saddr, inet->inet_dport,
1390                                    inet->inet_sport, sk->sk_protocol,
1391                                    RT_CONN_FLAGS(sk), sk->sk_bound_dev_if);
1392         if (IS_ERR(rt))
1393                 rt = NULL;
1394         if (rt)
1395                 sk_setup_caps(sk, &rt->dst);
1396         rcu_read_unlock();
1397
1398         return &rt->dst;
1399 }
1400
1401 struct dst_entry *inet_csk_update_pmtu(struct sock *sk, u32 mtu)
1402 {
1403         struct dst_entry *dst = __sk_dst_check(sk, 0);
1404         struct inet_sock *inet = inet_sk(sk);
1405
1406         if (!dst) {
1407                 dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
1408                 if (!dst)
1409                         goto out;
1410         }
1411         dst->ops->update_pmtu(dst, sk, NULL, mtu, true);
1412
1413         dst = __sk_dst_check(sk, 0);
1414         if (!dst)
1415                 dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
1416 out:
1417         return dst;
1418 }
1419 EXPORT_SYMBOL_GPL(inet_csk_update_pmtu);