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(const 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 void inet_sk_get_local_port_range(const struct sock *sk, int *low, int *high)
 134 {
 135         const struct inet_sock *inet = inet_sk(sk);
 136         const struct net *net = sock_net(sk);
 137         int lo, hi, sk_lo, sk_hi;
 138
 139         inet_get_local_port_range(net, &lo, &hi);
 140
 141         sk_lo = inet->local_port_range.lo;
 142         sk_hi = inet->local_port_range.hi;
 143
 144         if (unlikely(lo <= sk_lo && sk_lo <= hi))
 145                 lo = sk_lo;
 146         if (unlikely(lo <= sk_hi && sk_hi <= hi))
 147                 hi = sk_hi;
 148
 149         *low = lo;
 150         *high = hi;
 151 }
 152 EXPORT_SYMBOL(inet_sk_get_local_port_range);
 153
 154 static bool inet_use_bhash2_on_bind(const struct sock *sk)
 155 {
 156 #if IS_ENABLED(CONFIG_IPV6)
 157         if (sk->sk_family == AF_INET6) {
 158                 int addr_type = ipv6_addr_type(&sk->sk_v6_rcv_saddr);
 159
 160                 return addr_type != IPV6_ADDR_ANY &&
 161                         addr_type != IPV6_ADDR_MAPPED;
 162         }
 163 #endif
 164         return sk->sk_rcv_saddr != htonl(INADDR_ANY);
 165 }
 166
 167 static bool inet_bind_conflict(const struct sock *sk, struct sock *sk2,
 168                                kuid_t sk_uid, bool relax,
 169                                bool reuseport_cb_ok, bool reuseport_ok)
 170 {
 171         int bound_dev_if2;
 172
 173         if (sk == sk2)
 174                 return false;
 175
 176         bound_dev_if2 = READ_ONCE(sk2->sk_bound_dev_if);
 177
 178         if (!sk->sk_bound_dev_if || !bound_dev_if2 ||
 179             sk->sk_bound_dev_if == bound_dev_if2) {
 180                 if (sk->sk_reuse && sk2->sk_reuse &&
 181                     sk2->sk_state != TCP_LISTEN) {
 182                         if (!relax || (!reuseport_ok && sk->sk_reuseport &&
 183                                        sk2->sk_reuseport && reuseport_cb_ok &&
 184                                        (sk2->sk_state == TCP_TIME_WAIT ||
 185                                         uid_eq(sk_uid, sock_i_uid(sk2)))))
 186                                 return true;
 187                 } else if (!reuseport_ok || !sk->sk_reuseport ||
 188                            !sk2->sk_reuseport || !reuseport_cb_ok ||
 189                            (sk2->sk_state != TCP_TIME_WAIT &&
 190                             !uid_eq(sk_uid, sock_i_uid(sk2)))) {
 191                         return true;
 192                 }
 193         }
 194         return false;
 195 }
 196
 197 static bool __inet_bhash2_conflict(const struct sock *sk, struct sock *sk2,
 198                                    kuid_t sk_uid, bool relax,
 199                                    bool reuseport_cb_ok, bool reuseport_ok)
 200 {
 201         if (sk->sk_family == AF_INET && ipv6_only_sock(sk2))
 202                 return false;
 203
 204         return inet_bind_conflict(sk, sk2, sk_uid, relax,
 205                                   reuseport_cb_ok, reuseport_ok);
 206 }
 207
 208 static bool inet_bhash2_conflict(const struct sock *sk,
 209                                  const struct inet_bind2_bucket *tb2,
 210                                  kuid_t sk_uid,
 211                                  bool relax, bool reuseport_cb_ok,
 212                                  bool reuseport_ok)
 213 {
 214         struct inet_timewait_sock *tw2;
 215         struct sock *sk2;
 216
 217         sk_for_each_bound_bhash2(sk2, &tb2->owners) {
 218                 if (__inet_bhash2_conflict(sk, sk2, sk_uid, relax,
 219                                            reuseport_cb_ok, reuseport_ok))
 220                         return true;
 221         }
 222
 223         twsk_for_each_bound_bhash2(tw2, &tb2->deathrow) {
 224                 sk2 = (struct sock *)tw2;
 225
 226                 if (__inet_bhash2_conflict(sk, sk2, sk_uid, relax,
 227                                            reuseport_cb_ok, reuseport_ok))
 228                         return true;
 229         }
 230
 231         return false;
 232 }
 233
 234 /* This should be called only when the tb and tb2 hashbuckets' locks are held */
 235 static int inet_csk_bind_conflict(const struct sock *sk,
 236                                   const struct inet_bind_bucket *tb,
 237                                   const struct inet_bind2_bucket *tb2, /* may be null */
 238                                   bool relax, bool reuseport_ok)
 239 {
 240         bool reuseport_cb_ok;
 241         struct sock_reuseport *reuseport_cb;
 242         kuid_t uid = sock_i_uid((struct sock *)sk);
 243
 244         rcu_read_lock();
 245         reuseport_cb = rcu_dereference(sk->sk_reuseport_cb);
 246         /* paired with WRITE_ONCE() in __reuseport_(add|detach)_closed_sock */
 247         reuseport_cb_ok = !reuseport_cb || READ_ONCE(reuseport_cb->num_closed_socks);
 248         rcu_read_unlock();
 249
 250         /*
 251          * Unlike other sk lookup places we do not check
 252          * for sk_net here, since _all_ the socks listed
 253          * in tb->owners and tb2->owners list belong
 254          * to the same net - the one this bucket belongs to.
 255          */
 256
 257         if (!inet_use_bhash2_on_bind(sk)) {
 258                 struct sock *sk2;
 259
 260                 sk_for_each_bound(sk2, &tb->owners)
 261                         if (inet_bind_conflict(sk, sk2, uid, relax,
 262                                                reuseport_cb_ok, reuseport_ok) &&
 263                             inet_rcv_saddr_equal(sk, sk2, true))
 264                                 return true;
 265
 266                 return false;
 267         }
 268
 269         /* Conflicts with an existing IPV6_ADDR_ANY (if ipv6) or INADDR_ANY (if
 270          * ipv4) should have been checked already. We need to do these two
 271          * checks separately because their spinlocks have to be acquired/released
 272          * independently of each other, to prevent possible deadlocks
 273          */
 274         return tb2 && inet_bhash2_conflict(sk, tb2, uid, relax, reuseport_cb_ok,
 275                                            reuseport_ok);
 276 }
 277
 278 /* Determine if there is a bind conflict with an existing IPV6_ADDR_ANY (if ipv6) or
 279  * INADDR_ANY (if ipv4) socket.
 280  *
 281  * Caller must hold bhash hashbucket lock with local bh disabled, to protect
 282  * against concurrent binds on the port for addr any
 283  */
 284 static bool inet_bhash2_addr_any_conflict(const struct sock *sk, int port, int l3mdev,
 285                                           bool relax, bool reuseport_ok)
 286 {
 287         kuid_t uid = sock_i_uid((struct sock *)sk);
 288         const struct net *net = sock_net(sk);
 289         struct sock_reuseport *reuseport_cb;
 290         struct inet_bind_hashbucket *head2;
 291         struct inet_bind2_bucket *tb2;
 292         bool reuseport_cb_ok;
 293
 294         rcu_read_lock();
 295         reuseport_cb = rcu_dereference(sk->sk_reuseport_cb);
 296         /* paired with WRITE_ONCE() in __reuseport_(add|detach)_closed_sock */
 297         reuseport_cb_ok = !reuseport_cb || READ_ONCE(reuseport_cb->num_closed_socks);
 298         rcu_read_unlock();
 299
 300         head2 = inet_bhash2_addr_any_hashbucket(sk, net, port);
 301
 302         spin_lock(&head2->lock);
 303
 304         inet_bind_bucket_for_each(tb2, &head2->chain)
 305                 if (inet_bind2_bucket_match_addr_any(tb2, net, port, l3mdev, sk))
 306                         break;
 307
 308         if (tb2 && inet_bhash2_conflict(sk, tb2, uid, relax, reuseport_cb_ok,
 309                                         reuseport_ok)) {
 310                 spin_unlock(&head2->lock);
 311                 return true;
 312         }
 313
 314         spin_unlock(&head2->lock);
 315         return false;
 316 }
 317
 318 /*
 319  * Find an open port number for the socket.  Returns with the
 320  * inet_bind_hashbucket locks held if successful.
 321  */
 322 static struct inet_bind_hashbucket *
 323 inet_csk_find_open_port(const struct sock *sk, struct inet_bind_bucket **tb_ret,
 324                         struct inet_bind2_bucket **tb2_ret,
 325                         struct inet_bind_hashbucket **head2_ret, int *port_ret)
 326 {
 327         struct inet_hashinfo *hinfo = tcp_or_dccp_get_hashinfo(sk);
 328         int i, low, high, attempt_half, port, l3mdev;
 329         struct inet_bind_hashbucket *head, *head2;
 330         struct net *net = sock_net(sk);
 331         struct inet_bind2_bucket *tb2;
 332         struct inet_bind_bucket *tb;
 333         u32 remaining, offset;
 334         bool relax = false;
 335
 336         l3mdev = inet_sk_bound_l3mdev(sk);
 337 ports_exhausted:
 338         attempt_half = (sk->sk_reuse == SK_CAN_REUSE) ? 1 : 0;
 339 other_half_scan:
 340         inet_sk_get_local_port_range(sk, &low, &high);
 341         high++; /* [32768, 60999] -> [32768, 61000[ */
 342         if (high - low < 4)
 343                 attempt_half = 0;
 344         if (attempt_half) {
 345                 int half = low + (((high - low) >> 2) << 1);
 346
 347                 if (attempt_half == 1)
 348                         high = half;
 349                 else
 350                         low = half;
 351         }
 352         remaining = high - low;
 353         if (likely(remaining > 1))
 354                 remaining &= ~1U;
 355
 356         offset = get_random_u32_below(remaining);
 357         /* __inet_hash_connect() favors ports having @low parity
 358          * We do the opposite to not pollute connect() users.
 359          */
 360         offset |= 1U;
 361
 362 other_parity_scan:
 363         port = low + offset;
 364         for (i = 0; i < remaining; i += 2, port += 2) {
 365                 if (unlikely(port >= high))
 366                         port -= remaining;
 367                 if (inet_is_local_reserved_port(net, port))
 368                         continue;
 369                 head = &hinfo->bhash[inet_bhashfn(net, port,
 370                                                   hinfo->bhash_size)];
 371                 spin_lock_bh(&head->lock);
 372                 if (inet_use_bhash2_on_bind(sk)) {
 373                         if (inet_bhash2_addr_any_conflict(sk, port, l3mdev, relax, false))
 374                                 goto next_port;
 375                 }
 376
 377                 head2 = inet_bhashfn_portaddr(hinfo, sk, net, port);
 378                 spin_lock(&head2->lock);
 379                 tb2 = inet_bind2_bucket_find(head2, net, port, l3mdev, sk);
 380                 inet_bind_bucket_for_each(tb, &head->chain)
 381                         if (inet_bind_bucket_match(tb, net, port, l3mdev)) {
 382                                 if (!inet_csk_bind_conflict(sk, tb, tb2,
 383                                                             relax, false))
 384                                         goto success;
 385                                 spin_unlock(&head2->lock);
 386                                 goto next_port;
 387                         }
 388                 tb = NULL;
 389                 goto success;
 390 next_port:
 391                 spin_unlock_bh(&head->lock);
 392                 cond_resched();
 393         }
 394
 395         offset--;
 396         if (!(offset & 1))
 397                 goto other_parity_scan;
 398
 399         if (attempt_half == 1) {
 400                 /* OK we now try the upper half of the range */
 401                 attempt_half = 2;
 402                 goto other_half_scan;
 403         }
 404
 405         if (READ_ONCE(net->ipv4.sysctl_ip_autobind_reuse) && !relax) {
 406                 /* We still have a chance to connect to different destinations */
 407                 relax = true;
 408                 goto ports_exhausted;
 409         }
 410         return NULL;
 411 success:
 412         *port_ret = port;
 413         *tb_ret = tb;
 414         *tb2_ret = tb2;
 415         *head2_ret = head2;
 416         return head;
 417 }
 418
 419 static inline int sk_reuseport_match(struct inet_bind_bucket *tb,
 420                                      struct sock *sk)
 421 {
 422         kuid_t uid = sock_i_uid(sk);
 423
 424         if (tb->fastreuseport <= 0)
 425                 return 0;
 426         if (!sk->sk_reuseport)
 427                 return 0;
 428         if (rcu_access_pointer(sk->sk_reuseport_cb))
 429                 return 0;
 430         if (!uid_eq(tb->fastuid, uid))
 431                 return 0;
 432         /* We only need to check the rcv_saddr if this tb was once marked
 433          * without fastreuseport and then was reset, as we can only know that
 434          * the fast_*rcv_saddr doesn't have any conflicts with the socks on the
 435          * owners list.
 436          */
 437         if (tb->fastreuseport == FASTREUSEPORT_ANY)
 438                 return 1;
 439 #if IS_ENABLED(CONFIG_IPV6)
 440         if (tb->fast_sk_family == AF_INET6)
 441                 return ipv6_rcv_saddr_equal(&tb->fast_v6_rcv_saddr,
 442                                             inet6_rcv_saddr(sk),
 443                                             tb->fast_rcv_saddr,
 444                                             sk->sk_rcv_saddr,
 445                                             tb->fast_ipv6_only,
 446                                             ipv6_only_sock(sk), true, false);
 447 #endif
 448         return ipv4_rcv_saddr_equal(tb->fast_rcv_saddr, sk->sk_rcv_saddr,
 449                                     ipv6_only_sock(sk), true, false);
 450 }
 451
 452 void inet_csk_update_fastreuse(struct inet_bind_bucket *tb,
 453                                struct sock *sk)
 454 {
 455         kuid_t uid = sock_i_uid(sk);
 456         bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN;
 457
 458         if (hlist_empty(&tb->owners)) {
 459                 tb->fastreuse = reuse;
 460                 if (sk->sk_reuseport) {
 461                         tb->fastreuseport = FASTREUSEPORT_ANY;
 462                         tb->fastuid = uid;
 463                         tb->fast_rcv_saddr = sk->sk_rcv_saddr;
 464                         tb->fast_ipv6_only = ipv6_only_sock(sk);
 465                         tb->fast_sk_family = sk->sk_family;
 466 #if IS_ENABLED(CONFIG_IPV6)
 467                         tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
 468 #endif
 469                 } else {
 470                         tb->fastreuseport = 0;
 471                 }
 472         } else {
 473                 if (!reuse)
 474                         tb->fastreuse = 0;
 475                 if (sk->sk_reuseport) {
 476                         /* We didn't match or we don't have fastreuseport set on
 477                          * the tb, but we have sk_reuseport set on this socket
 478                          * and we know that there are no bind conflicts with
 479                          * this socket in this tb, so reset our tb's reuseport
 480                          * settings so that any subsequent sockets that match
 481                          * our current socket will be put on the fast path.
 482                          *
 483                          * If we reset we need to set FASTREUSEPORT_STRICT so we
 484                          * do extra checking for all subsequent sk_reuseport
 485                          * socks.
 486                          */
 487                         if (!sk_reuseport_match(tb, sk)) {
 488                                 tb->fastreuseport = FASTREUSEPORT_STRICT;
 489                                 tb->fastuid = uid;
 490                                 tb->fast_rcv_saddr = sk->sk_rcv_saddr;
 491                                 tb->fast_ipv6_only = ipv6_only_sock(sk);
 492                                 tb->fast_sk_family = sk->sk_family;
 493 #if IS_ENABLED(CONFIG_IPV6)
 494                                 tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
 495 #endif
 496                         }
 497                 } else {
 498                         tb->fastreuseport = 0;
 499                 }
 500         }
 501 }
 502
 503 /* Obtain a reference to a local port for the given sock,
 504  * if snum is zero it means select any available local port.
 505  * We try to allocate an odd port (and leave even ports for connect())
 506  */
 507 int inet_csk_get_port(struct sock *sk, unsigned short snum)
 508 {
 509         struct inet_hashinfo *hinfo = tcp_or_dccp_get_hashinfo(sk);
 510         bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN;
 511         bool found_port = false, check_bind_conflict = true;
 512         bool bhash_created = false, bhash2_created = false;
 513         int ret = -EADDRINUSE, port = snum, l3mdev;
 514         struct inet_bind_hashbucket *head, *head2;
 515         struct inet_bind2_bucket *tb2 = NULL;
 516         struct inet_bind_bucket *tb = NULL;
 517         bool head2_lock_acquired = false;
 518         struct net *net = sock_net(sk);
 519
 520         l3mdev = inet_sk_bound_l3mdev(sk);
 521
 522         if (!port) {
 523                 head = inet_csk_find_open_port(sk, &tb, &tb2, &head2, &port);
 524                 if (!head)
 525                         return ret;
 526
 527                 head2_lock_acquired = true;
 528
 529                 if (tb && tb2)
 530                         goto success;
 531                 found_port = true;
 532         } else {
 533                 head = &hinfo->bhash[inet_bhashfn(net, port,
 534                                                   hinfo->bhash_size)];
 535                 spin_lock_bh(&head->lock);
 536                 inet_bind_bucket_for_each(tb, &head->chain)
 537                         if (inet_bind_bucket_match(tb, net, port, l3mdev))
 538                                 break;
 539         }
 540
 541         if (!tb) {
 542                 tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep, net,
 543                                              head, port, l3mdev);
 544                 if (!tb)
 545                         goto fail_unlock;
 546                 bhash_created = true;
 547         }
 548
 549         if (!found_port) {
 550                 if (!hlist_empty(&tb->owners)) {
 551                         if (sk->sk_reuse == SK_FORCE_REUSE ||
 552                             (tb->fastreuse > 0 && reuse) ||
 553                             sk_reuseport_match(tb, sk))
 554                                 check_bind_conflict = false;
 555                 }
 556
 557                 if (check_bind_conflict && inet_use_bhash2_on_bind(sk)) {
 558                         if (inet_bhash2_addr_any_conflict(sk, port, l3mdev, true, true))
 559                                 goto fail_unlock;
 560                 }
 561
 562                 head2 = inet_bhashfn_portaddr(hinfo, sk, net, port);
 563                 spin_lock(&head2->lock);
 564                 head2_lock_acquired = true;
 565                 tb2 = inet_bind2_bucket_find(head2, net, port, l3mdev, sk);
 566         }
 567
 568         if (!tb2) {
 569                 tb2 = inet_bind2_bucket_create(hinfo->bind2_bucket_cachep,
 570                                                net, head2, port, l3mdev, sk);
 571                 if (!tb2)
 572                         goto fail_unlock;
 573                 bhash2_created = true;
 574         }
 575
 576         if (!found_port && check_bind_conflict) {
 577                 if (inet_csk_bind_conflict(sk, tb, tb2, true, true))
 578                         goto fail_unlock;
 579         }
 580
 581 success:
 582         inet_csk_update_fastreuse(tb, sk);
 583
 584         if (!inet_csk(sk)->icsk_bind_hash)
 585                 inet_bind_hash(sk, tb, tb2, port);
 586         WARN_ON(inet_csk(sk)->icsk_bind_hash != tb);
 587         WARN_ON(inet_csk(sk)->icsk_bind2_hash != tb2);
 588         ret = 0;
 589
 590 fail_unlock:
 591         if (ret) {
 592                 if (bhash_created)
 593                         inet_bind_bucket_destroy(hinfo->bind_bucket_cachep, tb);
 594                 if (bhash2_created)
 595                         inet_bind2_bucket_destroy(hinfo->bind2_bucket_cachep,
 596                                                   tb2);
 597         }
 598         if (head2_lock_acquired)
 599                 spin_unlock(&head2->lock);
 600         spin_unlock_bh(&head->lock);
 601         return ret;
 602 }
 603 EXPORT_SYMBOL_GPL(inet_csk_get_port);
 604
 605 /*
 606  * Wait for an incoming connection, avoid race conditions. This must be called
 607  * with the socket locked.
 608  */
 609 static int inet_csk_wait_for_connect(struct sock *sk, long timeo)
 610 {
 611         struct inet_connection_sock *icsk = inet_csk(sk);
 612         DEFINE_WAIT(wait);
 613         int err;
 614
 615         /*
 616          * True wake-one mechanism for incoming connections: only
 617          * one process gets woken up, not the 'whole herd'.
 618          * Since we do not 'race & poll' for established sockets
 619          * anymore, the common case will execute the loop only once.
 620          *
 621          * Subtle issue: "add_wait_queue_exclusive()" will be added
 622          * after any current non-exclusive waiters, and we know that
 623          * it will always _stay_ after any new non-exclusive waiters
 624          * because all non-exclusive waiters are added at the
 625          * beginning of the wait-queue. As such, it's ok to "drop"
 626          * our exclusiveness temporarily when we get woken up without
 627          * having to remove and re-insert us on the wait queue.
 628          */
 629         for (;;) {
 630                 prepare_to_wait_exclusive(sk_sleep(sk), &wait,
 631                                           TASK_INTERRUPTIBLE);
 632                 release_sock(sk);
 633                 if (reqsk_queue_empty(&icsk->icsk_accept_queue))
 634                         timeo = schedule_timeout(timeo);
 635                 sched_annotate_sleep();
 636                 lock_sock(sk);
 637                 err = 0;
 638                 if (!reqsk_queue_empty(&icsk->icsk_accept_queue))
 639                         break;
 640                 err = -EINVAL;
 641                 if (sk->sk_state != TCP_LISTEN)
 642                         break;
 643                 err = sock_intr_errno(timeo);
 644                 if (signal_pending(current))
 645                         break;
 646                 err = -EAGAIN;
 647                 if (!timeo)
 648                         break;
 649         }
 650         finish_wait(sk_sleep(sk), &wait);
 651         return err;
 652 }
 653
 654 /*
 655  * This will accept the next outstanding connection.
 656  */
 657 struct sock *inet_csk_accept(struct sock *sk, int flags, int *err, bool kern)
 658 {
 659         struct inet_connection_sock *icsk = inet_csk(sk);
 660         struct request_sock_queue *queue = &icsk->icsk_accept_queue;
 661         struct request_sock *req;
 662         struct sock *newsk;
 663         int error;
 664
 665         lock_sock(sk);
 666
 667         /* We need to make sure that this socket is listening,
 668          * and that it has something pending.
 669          */
 670         error = -EINVAL;
 671         if (sk->sk_state != TCP_LISTEN)
 672                 goto out_err;
 673
 674         /* Find already established connection */
 675         if (reqsk_queue_empty(queue)) {
 676                 long timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);
 677
 678                 /* If this is a non blocking socket don't sleep */
 679                 error = -EAGAIN;
 680                 if (!timeo)
 681                         goto out_err;
 682
 683                 error = inet_csk_wait_for_connect(sk, timeo);
 684                 if (error)
 685                         goto out_err;
 686         }
 687         req = reqsk_queue_remove(queue, sk);
 688         newsk = req->sk;
 689
 690         if (sk->sk_protocol == IPPROTO_TCP &&
 691             tcp_rsk(req)->tfo_listener) {
 692                 spin_lock_bh(&queue->fastopenq.lock);
 693                 if (tcp_rsk(req)->tfo_listener) {
 694                         /* We are still waiting for the final ACK from 3WHS
 695                          * so can't free req now. Instead, we set req->sk to
 696                          * NULL to signify that the child socket is taken
 697                          * so reqsk_fastopen_remove() will free the req
 698                          * when 3WHS finishes (or is aborted).
 699                          */
 700                         req->sk = NULL;
 701                         req = NULL;
 702                 }
 703                 spin_unlock_bh(&queue->fastopenq.lock);
 704         }
 705
 706 out:
 707         release_sock(sk);
 708         if (newsk && mem_cgroup_sockets_enabled) {
 709                 int amt = 0;
 710
 711                 /* atomically get the memory usage, set and charge the
 712                  * newsk->sk_memcg.
 713                  */
 714                 lock_sock(newsk);
 715
 716                 mem_cgroup_sk_alloc(newsk);
 717                 if (newsk->sk_memcg) {
 718                         /* The socket has not been accepted yet, no need
 719                          * to look at newsk->sk_wmem_queued.
 720                          */
 721                         amt = sk_mem_pages(newsk->sk_forward_alloc +
 722                                            atomic_read(&newsk->sk_rmem_alloc));
 723                 }
 724
 725                 if (amt)
 726                         mem_cgroup_charge_skmem(newsk->sk_memcg, amt,
 727                                                 GFP_KERNEL | __GFP_NOFAIL);
 728
 729                 release_sock(newsk);
 730         }
 731         if (req)
 732                 reqsk_put(req);
 733
 734         if (newsk)
 735                 inet_init_csk_locks(newsk);
 736
 737         return newsk;
 738 out_err:
 739         newsk = NULL;
 740         req = NULL;
 741         *err = error;
 742         goto out;
 743 }
 744 EXPORT_SYMBOL(inet_csk_accept);
 745
 746 /*
 747  * Using different timers for retransmit, delayed acks and probes
 748  * We may wish use just one timer maintaining a list of expire jiffies
 749  * to optimize.
 750  */
 751 void inet_csk_init_xmit_timers(struct sock *sk,
 752                                void (*retransmit_handler)(struct timer_list *t),
 753                                void (*delack_handler)(struct timer_list *t),
 754                                void (*keepalive_handler)(struct timer_list *t))
 755 {
 756         struct inet_connection_sock *icsk = inet_csk(sk);
 757
 758         timer_setup(&icsk->icsk_retransmit_timer, retransmit_handler, 0);
 759         timer_setup(&icsk->icsk_delack_timer, delack_handler, 0);
 760         timer_setup(&sk->sk_timer, keepalive_handler, 0);
 761         icsk->icsk_pending = icsk->icsk_ack.pending = 0;
 762 }
 763 EXPORT_SYMBOL(inet_csk_init_xmit_timers);
 764
 765 void inet_csk_clear_xmit_timers(struct sock *sk)
 766 {
 767         struct inet_connection_sock *icsk = inet_csk(sk);
 768
 769         icsk->icsk_pending = icsk->icsk_ack.pending = 0;
 770
 771         sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
 772         sk_stop_timer(sk, &icsk->icsk_delack_timer);
 773         sk_stop_timer(sk, &sk->sk_timer);
 774 }
 775 EXPORT_SYMBOL(inet_csk_clear_xmit_timers);
 776
 777 void inet_csk_delete_keepalive_timer(struct sock *sk)
 778 {
 779         sk_stop_timer(sk, &sk->sk_timer);
 780 }
 781 EXPORT_SYMBOL(inet_csk_delete_keepalive_timer);
 782
 783 void inet_csk_reset_keepalive_timer(struct sock *sk, unsigned long len)
 784 {
 785         sk_reset_timer(sk, &sk->sk_timer, jiffies + len);
 786 }
 787 EXPORT_SYMBOL(inet_csk_reset_keepalive_timer);
 788
 789 struct dst_entry *inet_csk_route_req(const struct sock *sk,
 790                                      struct flowi4 *fl4,
 791                                      const struct request_sock *req)
 792 {
 793         const struct inet_request_sock *ireq = inet_rsk(req);
 794         struct net *net = read_pnet(&ireq->ireq_net);
 795         struct ip_options_rcu *opt;
 796         struct rtable *rt;
 797
 798         rcu_read_lock();
 799         opt = rcu_dereference(ireq->ireq_opt);
 800
 801         flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
 802                            ip_sock_rt_tos(sk), ip_sock_rt_scope(sk),
 803                            sk->sk_protocol, inet_sk_flowi_flags(sk),
 804                            (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
 805                            ireq->ir_loc_addr, ireq->ir_rmt_port,
 806                            htons(ireq->ir_num), sk->sk_uid);
 807         security_req_classify_flow(req, flowi4_to_flowi_common(fl4));
 808         rt = ip_route_output_flow(net, fl4, sk);
 809         if (IS_ERR(rt))
 810                 goto no_route;
 811         if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
 812                 goto route_err;
 813         rcu_read_unlock();
 814         return &rt->dst;
 815
 816 route_err:
 817         ip_rt_put(rt);
 818 no_route:
 819         rcu_read_unlock();
 820         __IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
 821         return NULL;
 822 }
 823 EXPORT_SYMBOL_GPL(inet_csk_route_req);
 824
 825 struct dst_entry *inet_csk_route_child_sock(const struct sock *sk,
 826                                             struct sock *newsk,
 827                                             const struct request_sock *req)
 828 {
 829         const struct inet_request_sock *ireq = inet_rsk(req);
 830         struct net *net = read_pnet(&ireq->ireq_net);
 831         struct inet_sock *newinet = inet_sk(newsk);
 832         struct ip_options_rcu *opt;
 833         struct flowi4 *fl4;
 834         struct rtable *rt;
 835
 836         opt = rcu_dereference(ireq->ireq_opt);
 837         fl4 = &newinet->cork.fl.u.ip4;
 838
 839         flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
 840                            ip_sock_rt_tos(sk), ip_sock_rt_scope(sk),
 841                            sk->sk_protocol, inet_sk_flowi_flags(sk),
 842                            (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
 843                            ireq->ir_loc_addr, ireq->ir_rmt_port,
 844                            htons(ireq->ir_num), sk->sk_uid);
 845         security_req_classify_flow(req, flowi4_to_flowi_common(fl4));
 846         rt = ip_route_output_flow(net, fl4, sk);
 847         if (IS_ERR(rt))
 848                 goto no_route;
 849         if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
 850                 goto route_err;
 851         return &rt->dst;
 852
 853 route_err:
 854         ip_rt_put(rt);
 855 no_route:
 856         __IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
 857         return NULL;
 858 }
 859 EXPORT_SYMBOL_GPL(inet_csk_route_child_sock);
 860
 861 /* Decide when to expire the request and when to resend SYN-ACK */
 862 static void syn_ack_recalc(struct request_sock *req,
 863                            const int max_syn_ack_retries,
 864                            const u8 rskq_defer_accept,
 865                            int *expire, int *resend)
 866 {
 867         if (!rskq_defer_accept) {
 868                 *expire = req->num_timeout >= max_syn_ack_retries;
 869                 *resend = 1;
 870                 return;
 871         }
 872         *expire = req->num_timeout >= max_syn_ack_retries &&
 873                   (!inet_rsk(req)->acked || req->num_timeout >= rskq_defer_accept);
 874         /* Do not resend while waiting for data after ACK,
 875          * start to resend on end of deferring period to give
 876          * last chance for data or ACK to create established socket.
 877          */
 878         *resend = !inet_rsk(req)->acked ||
 879                   req->num_timeout >= rskq_defer_accept - 1;
 880 }
 881
 882 int inet_rtx_syn_ack(const struct sock *parent, struct request_sock *req)
 883 {
 884         int err = req->rsk_ops->rtx_syn_ack(parent, req);
 885
 886         if (!err)
 887                 req->num_retrans++;
 888         return err;
 889 }
 890 EXPORT_SYMBOL(inet_rtx_syn_ack);
 891
 892 static struct request_sock *inet_reqsk_clone(struct request_sock *req,
 893                                              struct sock *sk)
 894 {
 895         struct sock *req_sk, *nreq_sk;
 896         struct request_sock *nreq;
 897
 898         nreq = kmem_cache_alloc(req->rsk_ops->slab, GFP_ATOMIC | __GFP_NOWARN);
 899         if (!nreq) {
 900                 __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQFAILURE);
 901
 902                 /* paired with refcount_inc_not_zero() in reuseport_migrate_sock() */
 903                 sock_put(sk);
 904                 return NULL;
 905         }
 906
 907         req_sk = req_to_sk(req);
 908         nreq_sk = req_to_sk(nreq);
 909
 910         memcpy(nreq_sk, req_sk,
 911                offsetof(struct sock, sk_dontcopy_begin));
 912         memcpy(&nreq_sk->sk_dontcopy_end, &req_sk->sk_dontcopy_end,
 913                req->rsk_ops->obj_size - offsetof(struct sock, sk_dontcopy_end));
 914
 915         sk_node_init(&nreq_sk->sk_node);
 916         nreq_sk->sk_tx_queue_mapping = req_sk->sk_tx_queue_mapping;
 917 #ifdef CONFIG_SOCK_RX_QUEUE_MAPPING
 918         nreq_sk->sk_rx_queue_mapping = req_sk->sk_rx_queue_mapping;
 919 #endif
 920         nreq_sk->sk_incoming_cpu = req_sk->sk_incoming_cpu;
 921
 922         nreq->rsk_listener = sk;
 923
 924         /* We need not acquire fastopenq->lock
 925          * because the child socket is locked in inet_csk_listen_stop().
 926          */
 927         if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(nreq)->tfo_listener)
 928                 rcu_assign_pointer(tcp_sk(nreq->sk)->fastopen_rsk, nreq);
 929
 930         return nreq;
 931 }
 932
 933 static void reqsk_queue_migrated(struct request_sock_queue *queue,
 934                                  const struct request_sock *req)
 935 {
 936         if (req->num_timeout == 0)
 937                 atomic_inc(&queue->young);
 938         atomic_inc(&queue->qlen);
 939 }
 940
 941 static void reqsk_migrate_reset(struct request_sock *req)
 942 {
 943         req->saved_syn = NULL;
 944 #if IS_ENABLED(CONFIG_IPV6)
 945         inet_rsk(req)->ipv6_opt = NULL;
 946         inet_rsk(req)->pktopts = NULL;
 947 #else
 948         inet_rsk(req)->ireq_opt = NULL;
 949 #endif
 950 }
 951
 952 /* return true if req was found in the ehash table */
 953 static bool reqsk_queue_unlink(struct request_sock *req)
 954 {
 955         struct sock *sk = req_to_sk(req);
 956         bool found = false;
 957
 958         if (sk_hashed(sk)) {
 959                 struct inet_hashinfo *hashinfo = tcp_or_dccp_get_hashinfo(sk);
 960                 spinlock_t *lock = inet_ehash_lockp(hashinfo, req->rsk_hash);
 961
 962                 spin_lock(lock);
 963                 found = __sk_nulls_del_node_init_rcu(sk);
 964                 spin_unlock(lock);
 965         }
 966         if (timer_pending(&req->rsk_timer) && del_timer_sync(&req->rsk_timer))
 967                 reqsk_put(req);
 968         return found;
 969 }
 970
 971 bool inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req)
 972 {
 973         bool unlinked = reqsk_queue_unlink(req);
 974
 975         if (unlinked) {
 976                 reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req);
 977                 reqsk_put(req);
 978         }
 979         return unlinked;
 980 }
 981 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop);
 982
 983 void inet_csk_reqsk_queue_drop_and_put(struct sock *sk, struct request_sock *req)
 984 {
 985         inet_csk_reqsk_queue_drop(sk, req);
 986         reqsk_put(req);
 987 }
 988 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop_and_put);
 989
 990 static void reqsk_timer_handler(struct timer_list *t)
 991 {
 992         struct request_sock *req = from_timer(req, t, rsk_timer);
 993         struct request_sock *nreq = NULL, *oreq = req;
 994         struct sock *sk_listener = req->rsk_listener;
 995         struct inet_connection_sock *icsk;
 996         struct request_sock_queue *queue;
 997         struct net *net;
 998         int max_syn_ack_retries, qlen, expire = 0, resend = 0;
 999
1000         if (inet_sk_state_load(sk_listener) != TCP_LISTEN) {
1001                 struct sock *nsk;
1002
1003                 nsk = reuseport_migrate_sock(sk_listener, req_to_sk(req), NULL);
1004                 if (!nsk)
1005                         goto drop;
1006
1007                 nreq = inet_reqsk_clone(req, nsk);
1008                 if (!nreq)
1009                         goto drop;
1010
1011                 /* The new timer for the cloned req can decrease the 2
1012                  * by calling inet_csk_reqsk_queue_drop_and_put(), so
1013                  * hold another count to prevent use-after-free and
1014                  * call reqsk_put() just before return.
1015                  */
1016                 refcount_set(&nreq->rsk_refcnt, 2 + 1);
1017                 timer_setup(&nreq->rsk_timer, reqsk_timer_handler, TIMER_PINNED);
1018                 reqsk_queue_migrated(&inet_csk(nsk)->icsk_accept_queue, req);
1019
1020                 req = nreq;
1021                 sk_listener = nsk;
1022         }
1023
1024         icsk = inet_csk(sk_listener);
1025         net = sock_net(sk_listener);
1026         max_syn_ack_retries = READ_ONCE(icsk->icsk_syn_retries) ? :
1027                 READ_ONCE(net->ipv4.sysctl_tcp_synack_retries);
1028         /* Normally all the openreqs are young and become mature
1029          * (i.e. converted to established socket) for first timeout.
1030          * If synack was not acknowledged for 1 second, it means
1031          * one of the following things: synack was lost, ack was lost,
1032          * rtt is high or nobody planned to ack (i.e. synflood).
1033          * When server is a bit loaded, queue is populated with old
1034          * open requests, reducing effective size of queue.
1035          * When server is well loaded, queue size reduces to zero
1036          * after several minutes of work. It is not synflood,
1037          * it is normal operation. The solution is pruning
1038          * too old entries overriding normal timeout, when
1039          * situation becomes dangerous.
1040          *
1041          * Essentially, we reserve half of room for young
1042          * embrions; and abort old ones without pity, if old
1043          * ones are about to clog our table.
1044          */
1045         queue = &icsk->icsk_accept_queue;
1046         qlen = reqsk_queue_len(queue);
1047         if ((qlen << 1) > max(8U, READ_ONCE(sk_listener->sk_max_ack_backlog))) {
1048                 int young = reqsk_queue_len_young(queue) << 1;
1049
1050                 while (max_syn_ack_retries > 2) {
1051                         if (qlen < young)
1052                                 break;
1053                         max_syn_ack_retries--;
1054                         young <<= 1;
1055                 }
1056         }
1057         syn_ack_recalc(req, max_syn_ack_retries, READ_ONCE(queue->rskq_defer_accept),
1058                        &expire, &resend);
1059         req->rsk_ops->syn_ack_timeout(req);
1060         if (!expire &&
1061             (!resend ||
1062              !inet_rtx_syn_ack(sk_listener, req) ||
1063              inet_rsk(req)->acked)) {
1064                 if (req->num_timeout++ == 0)
1065                         atomic_dec(&queue->young);
1066                 mod_timer(&req->rsk_timer, jiffies + reqsk_timeout(req, TCP_RTO_MAX));
1067
1068                 if (!nreq)
1069                         return;
1070
1071                 if (!inet_ehash_insert(req_to_sk(nreq), req_to_sk(oreq), NULL)) {
1072                         /* delete timer */
1073                         inet_csk_reqsk_queue_drop(sk_listener, nreq);
1074                         goto no_ownership;
1075                 }
1076
1077                 __NET_INC_STATS(net, LINUX_MIB_TCPMIGRATEREQSUCCESS);
1078                 reqsk_migrate_reset(oreq);
1079                 reqsk_queue_removed(&inet_csk(oreq->rsk_listener)->icsk_accept_queue, oreq);
1080                 reqsk_put(oreq);
1081
1082                 reqsk_put(nreq);
1083                 return;
1084         }
1085
1086         /* Even if we can clone the req, we may need not retransmit any more
1087          * SYN+ACKs (nreq->num_timeout > max_syn_ack_retries, etc), or another
1088          * CPU may win the "own_req" race so that inet_ehash_insert() fails.
1089          */
1090         if (nreq) {
1091                 __NET_INC_STATS(net, LINUX_MIB_TCPMIGRATEREQFAILURE);
1092 no_ownership:
1093                 reqsk_migrate_reset(nreq);
1094                 reqsk_queue_removed(queue, nreq);
1095                 __reqsk_free(nreq);
1096         }
1097
1098 drop:
1099         inet_csk_reqsk_queue_drop_and_put(oreq->rsk_listener, oreq);
1100 }
1101
1102 static void reqsk_queue_hash_req(struct request_sock *req,
1103                                  unsigned long timeout)
1104 {
1105         timer_setup(&req->rsk_timer, reqsk_timer_handler, TIMER_PINNED);
1106         mod_timer(&req->rsk_timer, jiffies + timeout);
1107
1108         inet_ehash_insert(req_to_sk(req), NULL, NULL);
1109         /* before letting lookups find us, make sure all req fields
1110          * are committed to memory and refcnt initialized.
1111          */
1112         smp_wmb();
1113         refcount_set(&req->rsk_refcnt, 2 + 1);
1114 }
1115
1116 void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
1117                                    unsigned long timeout)
1118 {
1119         reqsk_queue_hash_req(req, timeout);
1120         inet_csk_reqsk_queue_added(sk);
1121 }
1122 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add);
1123
1124 static void inet_clone_ulp(const struct request_sock *req, struct sock *newsk,
1125                            const gfp_t priority)
1126 {
1127         struct inet_connection_sock *icsk = inet_csk(newsk);
1128
1129         if (!icsk->icsk_ulp_ops)
1130                 return;
1131
1132         icsk->icsk_ulp_ops->clone(req, newsk, priority);
1133 }
1134
1135 /**
1136  *      inet_csk_clone_lock - clone an inet socket, and lock its clone
1137  *      @sk: the socket to clone
1138  *      @req: request_sock
1139  *      @priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc)
1140  *
1141  *      Caller must unlock socket even in error path (bh_unlock_sock(newsk))
1142  */
1143 struct sock *inet_csk_clone_lock(const struct sock *sk,
1144                                  const struct request_sock *req,
1145                                  const gfp_t priority)
1146 {
1147         struct sock *newsk = sk_clone_lock(sk, priority);
1148
1149         if (newsk) {
1150                 struct inet_connection_sock *newicsk = inet_csk(newsk);
1151
1152                 inet_sk_set_state(newsk, TCP_SYN_RECV);
1153                 newicsk->icsk_bind_hash = NULL;
1154                 newicsk->icsk_bind2_hash = NULL;
1155
1156                 inet_sk(newsk)->inet_dport = inet_rsk(req)->ir_rmt_port;
1157                 inet_sk(newsk)->inet_num = inet_rsk(req)->ir_num;
1158                 inet_sk(newsk)->inet_sport = htons(inet_rsk(req)->ir_num);
1159
1160                 /* listeners have SOCK_RCU_FREE, not the children */
1161                 sock_reset_flag(newsk, SOCK_RCU_FREE);
1162
1163                 inet_sk(newsk)->mc_list = NULL;
1164
1165                 newsk->sk_mark = inet_rsk(req)->ir_mark;
1166                 atomic64_set(&newsk->sk_cookie,
1167                              atomic64_read(&inet_rsk(req)->ir_cookie));
1168
1169                 newicsk->icsk_retransmits = 0;
1170                 newicsk->icsk_backoff     = 0;
1171                 newicsk->icsk_probes_out  = 0;
1172                 newicsk->icsk_probes_tstamp = 0;
1173
1174                 /* Deinitialize accept_queue to trap illegal accesses. */
1175                 memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue));
1176
1177                 inet_clone_ulp(req, newsk, priority);
1178
1179                 security_inet_csk_clone(newsk, req);
1180         }
1181         return newsk;
1182 }
1183 EXPORT_SYMBOL_GPL(inet_csk_clone_lock);
1184
1185 /*
1186  * At this point, there should be no process reference to this
1187  * socket, and thus no user references at all.  Therefore we
1188  * can assume the socket waitqueue is inactive and nobody will
1189  * try to jump onto it.
1190  */
1191 void inet_csk_destroy_sock(struct sock *sk)
1192 {
1193         WARN_ON(sk->sk_state != TCP_CLOSE);
1194         WARN_ON(!sock_flag(sk, SOCK_DEAD));
1195
1196         /* It cannot be in hash table! */
1197         WARN_ON(!sk_unhashed(sk));
1198
1199         /* If it has not 0 inet_sk(sk)->inet_num, it must be bound */
1200         WARN_ON(inet_sk(sk)->inet_num && !inet_csk(sk)->icsk_bind_hash);
1201
1202         sk->sk_prot->destroy(sk);
1203
1204         sk_stream_kill_queues(sk);
1205
1206         xfrm_sk_free_policy(sk);
1207
1208         this_cpu_dec(*sk->sk_prot->orphan_count);
1209
1210         sock_put(sk);
1211 }
1212 EXPORT_SYMBOL(inet_csk_destroy_sock);
1213
1214 /* This function allows to force a closure of a socket after the call to
1215  * tcp/dccp_create_openreq_child().
1216  */
1217 void inet_csk_prepare_forced_close(struct sock *sk)
1218         __releases(&sk->sk_lock.slock)
1219 {
1220         /* sk_clone_lock locked the socket and set refcnt to 2 */
1221         bh_unlock_sock(sk);
1222         sock_put(sk);
1223         inet_csk_prepare_for_destroy_sock(sk);
1224         inet_sk(sk)->inet_num = 0;
1225 }
1226 EXPORT_SYMBOL(inet_csk_prepare_forced_close);
1227
1228 static int inet_ulp_can_listen(const struct sock *sk)
1229 {
1230         const struct inet_connection_sock *icsk = inet_csk(sk);
1231
1232         if (icsk->icsk_ulp_ops && !icsk->icsk_ulp_ops->clone)
1233                 return -EINVAL;
1234
1235         return 0;
1236 }
1237
1238 int inet_csk_listen_start(struct sock *sk)
1239 {
1240         struct inet_connection_sock *icsk = inet_csk(sk);
1241         struct inet_sock *inet = inet_sk(sk);
1242         int err;
1243
1244         err = inet_ulp_can_listen(sk);
1245         if (unlikely(err))
1246                 return err;
1247
1248         reqsk_queue_alloc(&icsk->icsk_accept_queue);
1249
1250         sk->sk_ack_backlog = 0;
1251         inet_csk_delack_init(sk);
1252
1253         /* There is race window here: we announce ourselves listening,
1254          * but this transition is still not validated by get_port().
1255          * It is OK, because this socket enters to hash table only
1256          * after validation is complete.
1257          */
1258         inet_sk_state_store(sk, TCP_LISTEN);
1259         err = sk->sk_prot->get_port(sk, inet->inet_num);
1260         if (!err) {
1261                 inet->inet_sport = htons(inet->inet_num);
1262
1263                 sk_dst_reset(sk);
1264                 err = sk->sk_prot->hash(sk);
1265
1266                 if (likely(!err))
1267                         return 0;
1268         }
1269
1270         inet_sk_set_state(sk, TCP_CLOSE);
1271         return err;
1272 }
1273 EXPORT_SYMBOL_GPL(inet_csk_listen_start);
1274
1275 static void inet_child_forget(struct sock *sk, struct request_sock *req,
1276                               struct sock *child)
1277 {
1278         sk->sk_prot->disconnect(child, O_NONBLOCK);
1279
1280         sock_orphan(child);
1281
1282         this_cpu_inc(*sk->sk_prot->orphan_count);
1283
1284         if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(req)->tfo_listener) {
1285                 BUG_ON(rcu_access_pointer(tcp_sk(child)->fastopen_rsk) != req);
1286                 BUG_ON(sk != req->rsk_listener);
1287
1288                 /* Paranoid, to prevent race condition if
1289                  * an inbound pkt destined for child is
1290                  * blocked by sock lock in tcp_v4_rcv().
1291                  * Also to satisfy an assertion in
1292                  * tcp_v4_destroy_sock().
1293                  */
1294                 RCU_INIT_POINTER(tcp_sk(child)->fastopen_rsk, NULL);
1295         }
1296         inet_csk_destroy_sock(child);
1297 }
1298
1299 struct sock *inet_csk_reqsk_queue_add(struct sock *sk,
1300                                       struct request_sock *req,
1301                                       struct sock *child)
1302 {
1303         struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
1304
1305         spin_lock(&queue->rskq_lock);
1306         if (unlikely(sk->sk_state != TCP_LISTEN)) {
1307                 inet_child_forget(sk, req, child);
1308                 child = NULL;
1309         } else {
1310                 req->sk = child;
1311                 req->dl_next = NULL;
1312                 if (queue->rskq_accept_head == NULL)
1313                         WRITE_ONCE(queue->rskq_accept_head, req);
1314                 else
1315                         queue->rskq_accept_tail->dl_next = req;
1316                 queue->rskq_accept_tail = req;
1317                 sk_acceptq_added(sk);
1318         }
1319         spin_unlock(&queue->rskq_lock);
1320         return child;
1321 }
1322 EXPORT_SYMBOL(inet_csk_reqsk_queue_add);
1323
1324 struct sock *inet_csk_complete_hashdance(struct sock *sk, struct sock *child,
1325                                          struct request_sock *req, bool own_req)
1326 {
1327         if (own_req) {
1328                 inet_csk_reqsk_queue_drop(req->rsk_listener, req);
1329                 reqsk_queue_removed(&inet_csk(req->rsk_listener)->icsk_accept_queue, req);
1330
1331                 if (sk != req->rsk_listener) {
1332                         /* another listening sk has been selected,
1333                          * migrate the req to it.
1334                          */
1335                         struct request_sock *nreq;
1336
1337                         /* hold a refcnt for the nreq->rsk_listener
1338                          * which is assigned in inet_reqsk_clone()
1339                          */
1340                         sock_hold(sk);
1341                         nreq = inet_reqsk_clone(req, sk);
1342                         if (!nreq) {
1343                                 inet_child_forget(sk, req, child);
1344                                 goto child_put;
1345                         }
1346
1347                         refcount_set(&nreq->rsk_refcnt, 1);
1348                         if (inet_csk_reqsk_queue_add(sk, nreq, child)) {
1349                                 __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQSUCCESS);
1350                                 reqsk_migrate_reset(req);
1351                                 reqsk_put(req);
1352                                 return child;
1353                         }
1354
1355                         __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQFAILURE);
1356                         reqsk_migrate_reset(nreq);
1357                         __reqsk_free(nreq);
1358                 } else if (inet_csk_reqsk_queue_add(sk, req, child)) {
1359                         return child;
1360                 }
1361         }
1362         /* Too bad, another child took ownership of the request, undo. */
1363 child_put:
1364         bh_unlock_sock(child);
1365         sock_put(child);
1366         return NULL;
1367 }
1368 EXPORT_SYMBOL(inet_csk_complete_hashdance);
1369
1370 /*
1371  *      This routine closes sockets which have been at least partially
1372  *      opened, but not yet accepted.
1373  */
1374 void inet_csk_listen_stop(struct sock *sk)
1375 {
1376         struct inet_connection_sock *icsk = inet_csk(sk);
1377         struct request_sock_queue *queue = &icsk->icsk_accept_queue;
1378         struct request_sock *next, *req;
1379
1380         /* Following specs, it would be better either to send FIN
1381          * (and enter FIN-WAIT-1, it is normal close)
1382          * or to send active reset (abort).
1383          * Certainly, it is pretty dangerous while synflood, but it is
1384          * bad justification for our negligence 8)
1385          * To be honest, we are not able to make either
1386          * of the variants now.                 --ANK
1387          */
1388         while ((req = reqsk_queue_remove(queue, sk)) != NULL) {
1389                 struct sock *child = req->sk, *nsk;
1390                 struct request_sock *nreq;
1391
1392                 local_bh_disable();
1393                 bh_lock_sock(child);
1394                 WARN_ON(sock_owned_by_user(child));
1395                 sock_hold(child);
1396
1397                 nsk = reuseport_migrate_sock(sk, child, NULL);
1398                 if (nsk) {
1399                         nreq = inet_reqsk_clone(req, nsk);
1400                         if (nreq) {
1401                                 refcount_set(&nreq->rsk_refcnt, 1);
1402
1403                                 if (inet_csk_reqsk_queue_add(nsk, nreq, child)) {
1404                                         __NET_INC_STATS(sock_net(nsk),
1405                                                         LINUX_MIB_TCPMIGRATEREQSUCCESS);
1406                                         reqsk_migrate_reset(req);
1407                                 } else {
1408                                         __NET_INC_STATS(sock_net(nsk),
1409                                                         LINUX_MIB_TCPMIGRATEREQFAILURE);
1410                                         reqsk_migrate_reset(nreq);
1411                                         __reqsk_free(nreq);
1412                                 }
1413
1414                                 /* inet_csk_reqsk_queue_add() has already
1415                                  * called inet_child_forget() on failure case.
1416                                  */
1417                                 goto skip_child_forget;
1418                         }
1419                 }
1420
1421                 inet_child_forget(sk, req, child);
1422 skip_child_forget:
1423                 reqsk_put(req);
1424                 bh_unlock_sock(child);
1425                 local_bh_enable();
1426                 sock_put(child);
1427
1428                 cond_resched();
1429         }
1430         if (queue->fastopenq.rskq_rst_head) {
1431                 /* Free all the reqs queued in rskq_rst_head. */
1432                 spin_lock_bh(&queue->fastopenq.lock);
1433                 req = queue->fastopenq.rskq_rst_head;
1434                 queue->fastopenq.rskq_rst_head = NULL;
1435                 spin_unlock_bh(&queue->fastopenq.lock);
1436                 while (req != NULL) {
1437                         next = req->dl_next;
1438                         reqsk_put(req);
1439                         req = next;
1440                 }
1441         }
1442         WARN_ON_ONCE(sk->sk_ack_backlog);
1443 }
1444 EXPORT_SYMBOL_GPL(inet_csk_listen_stop);
1445
1446 void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr)
1447 {
1448         struct sockaddr_in *sin = (struct sockaddr_in *)uaddr;
1449         const struct inet_sock *inet = inet_sk(sk);
1450
1451         sin->sin_family         = AF_INET;
1452         sin->sin_addr.s_addr    = inet->inet_daddr;
1453         sin->sin_port           = inet->inet_dport;
1454 }
1455 EXPORT_SYMBOL_GPL(inet_csk_addr2sockaddr);
1456
1457 static struct dst_entry *inet_csk_rebuild_route(struct sock *sk, struct flowi *fl)
1458 {
1459         const struct inet_sock *inet = inet_sk(sk);
1460         const struct ip_options_rcu *inet_opt;
1461         __be32 daddr = inet->inet_daddr;
1462         struct flowi4 *fl4;
1463         struct rtable *rt;
1464
1465         rcu_read_lock();
1466         inet_opt = rcu_dereference(inet->inet_opt);
1467         if (inet_opt && inet_opt->opt.srr)
1468                 daddr = inet_opt->opt.faddr;
1469         fl4 = &fl->u.ip4;
1470         rt = ip_route_output_ports(sock_net(sk), fl4, sk, daddr,
1471                                    inet->inet_saddr, inet->inet_dport,
1472                                    inet->inet_sport, sk->sk_protocol,
1473                                    RT_CONN_FLAGS(sk), sk->sk_bound_dev_if);
1474         if (IS_ERR(rt))
1475                 rt = NULL;
1476         if (rt)
1477                 sk_setup_caps(sk, &rt->dst);
1478         rcu_read_unlock();
1479
1480         return &rt->dst;
1481 }
1482
1483 struct dst_entry *inet_csk_update_pmtu(struct sock *sk, u32 mtu)
1484 {
1485         struct dst_entry *dst = __sk_dst_check(sk, 0);
1486         struct inet_sock *inet = inet_sk(sk);
1487
1488         if (!dst) {
1489                 dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
1490                 if (!dst)
1491                         goto out;
1492         }
1493         dst->ops->update_pmtu(dst, sk, NULL, mtu, true);
1494
1495         dst = __sk_dst_check(sk, 0);
1496         if (!dst)
1497                 dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
1498 out:
1499         return dst;
1500 }
1501 EXPORT_SYMBOL_GPL(inet_csk_update_pmtu);