net/ipv4/inet_connection_sock.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   4  *              operating system.  INET is implemented using the  BSD Socket
   5  *              interface as the means of communication with the user level.
   6  *
   7  *              Support for INET connection oriented protocols.
   8  *
   9  * Authors:     See the TCP sources
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/jhash.h>
  14
  15 #include <net/inet_connection_sock.h>
  16 #include <net/inet_hashtables.h>
  17 #include <net/inet_timewait_sock.h>
  18 #include <net/ip.h>
  19 #include <net/route.h>
  20 #include <net/tcp_states.h>
  21 #include <net/xfrm.h>
  22 #include <net/tcp.h>
  23 #include <net/sock_reuseport.h>
  24 #include <net/addrconf.h>
  25
  26 #if IS_ENABLED(CONFIG_IPV6)
  27 /* match_sk*_wildcard == true:  IPV6_ADDR_ANY equals to any IPv6 addresses
  28  *                              if IPv6 only, and any IPv4 addresses
  29  *                              if not IPv6 only
  30  * match_sk*_wildcard == false: addresses must be exactly the same, i.e.
  31  *                              IPV6_ADDR_ANY only equals to IPV6_ADDR_ANY,
  32  *                              and 0.0.0.0 equals to 0.0.0.0 only
  33  */
  34 static bool ipv6_rcv_saddr_equal(const struct in6_addr *sk1_rcv_saddr6,
  35                                  const struct in6_addr *sk2_rcv_saddr6,
  36                                  __be32 sk1_rcv_saddr, __be32 sk2_rcv_saddr,
  37                                  bool sk1_ipv6only, bool sk2_ipv6only,
  38                                  bool match_sk1_wildcard,
  39                                  bool match_sk2_wildcard)
  40 {
  41         int addr_type = ipv6_addr_type(sk1_rcv_saddr6);
  42         int addr_type2 = sk2_rcv_saddr6 ? ipv6_addr_type(sk2_rcv_saddr6) : IPV6_ADDR_MAPPED;
  43
  44         /* if both are mapped, treat as IPv4 */
  45         if (addr_type == IPV6_ADDR_MAPPED && addr_type2 == IPV6_ADDR_MAPPED) {
  46                 if (!sk2_ipv6only) {
  47                         if (sk1_rcv_saddr == sk2_rcv_saddr)
  48                                 return true;
  49                         return (match_sk1_wildcard && !sk1_rcv_saddr) ||
  50                                 (match_sk2_wildcard && !sk2_rcv_saddr);
  51                 }
  52                 return false;
  53         }
  54
  55         if (addr_type == IPV6_ADDR_ANY && addr_type2 == IPV6_ADDR_ANY)
  56                 return true;
  57
  58         if (addr_type2 == IPV6_ADDR_ANY && match_sk2_wildcard &&
  59             !(sk2_ipv6only && addr_type == IPV6_ADDR_MAPPED))
  60                 return true;
  61
  62         if (addr_type == IPV6_ADDR_ANY && match_sk1_wildcard &&
  63             !(sk1_ipv6only && addr_type2 == IPV6_ADDR_MAPPED))
  64                 return true;
  65
  66         if (sk2_rcv_saddr6 &&
  67             ipv6_addr_equal(sk1_rcv_saddr6, sk2_rcv_saddr6))
  68                 return true;
  69
  70         return false;
  71 }
  72 #endif
  73
  74 /* match_sk*_wildcard == true:  0.0.0.0 equals to any IPv4 addresses
  75  * match_sk*_wildcard == false: addresses must be exactly the same, i.e.
  76  *                              0.0.0.0 only equals to 0.0.0.0
  77  */
  78 static bool ipv4_rcv_saddr_equal(__be32 sk1_rcv_saddr, __be32 sk2_rcv_saddr,
  79                                  bool sk2_ipv6only, bool match_sk1_wildcard,
  80                                  bool match_sk2_wildcard)
  81 {
  82         if (!sk2_ipv6only) {
  83                 if (sk1_rcv_saddr == sk2_rcv_saddr)
  84                         return true;
  85                 return (match_sk1_wildcard && !sk1_rcv_saddr) ||
  86                         (match_sk2_wildcard && !sk2_rcv_saddr);
  87         }
  88         return false;
  89 }
  90
  91 bool inet_rcv_saddr_equal(const struct sock *sk, const struct sock *sk2,
  92                           bool match_wildcard)
  93 {
  94 #if IS_ENABLED(CONFIG_IPV6)
  95         if (sk->sk_family == AF_INET6)
  96                 return ipv6_rcv_saddr_equal(&sk->sk_v6_rcv_saddr,
  97                                             inet6_rcv_saddr(sk2),
  98                                             sk->sk_rcv_saddr,
  99                                             sk2->sk_rcv_saddr,
 100                                             ipv6_only_sock(sk),
 101                                             ipv6_only_sock(sk2),
 102                                             match_wildcard,
 103                                             match_wildcard);
 104 #endif
 105         return ipv4_rcv_saddr_equal(sk->sk_rcv_saddr, sk2->sk_rcv_saddr,
 106                                     ipv6_only_sock(sk2), match_wildcard,
 107                                     match_wildcard);
 108 }
 109 EXPORT_SYMBOL(inet_rcv_saddr_equal);
 110
 111 bool inet_rcv_saddr_any(const struct sock *sk)
 112 {
 113 #if IS_ENABLED(CONFIG_IPV6)
 114         if (sk->sk_family == AF_INET6)
 115                 return ipv6_addr_any(&sk->sk_v6_rcv_saddr);
 116 #endif
 117         return !sk->sk_rcv_saddr;
 118 }
 119
 120 void inet_get_local_port_range(struct net *net, int *low, int *high)
 121 {
 122         unsigned int seq;
 123
 124         do {
 125                 seq = read_seqbegin(&net->ipv4.ip_local_ports.lock);
 126
 127                 *low = net->ipv4.ip_local_ports.range[0];
 128                 *high = net->ipv4.ip_local_ports.range[1];
 129         } while (read_seqretry(&net->ipv4.ip_local_ports.lock, seq));
 130 }
 131 EXPORT_SYMBOL(inet_get_local_port_range);
 132
 133 static bool inet_use_bhash2_on_bind(const struct sock *sk)
 134 {
 135 #if IS_ENABLED(CONFIG_IPV6)
 136         if (sk->sk_family == AF_INET6) {
 137                 int addr_type = ipv6_addr_type(&sk->sk_v6_rcv_saddr);
 138
 139                 return addr_type != IPV6_ADDR_ANY &&
 140                         addr_type != IPV6_ADDR_MAPPED;
 141         }
 142 #endif
 143         return sk->sk_rcv_saddr != htonl(INADDR_ANY);
 144 }
 145
 146 static bool inet_bind_conflict(const struct sock *sk, struct sock *sk2,
 147                                kuid_t sk_uid, bool relax,
 148                                bool reuseport_cb_ok, bool reuseport_ok)
 149 {
 150         int bound_dev_if2;
 151
 152         if (sk == sk2)
 153                 return false;
 154
 155         bound_dev_if2 = READ_ONCE(sk2->sk_bound_dev_if);
 156
 157         if (!sk->sk_bound_dev_if || !bound_dev_if2 ||
 158             sk->sk_bound_dev_if == bound_dev_if2) {
 159                 if (sk->sk_reuse && sk2->sk_reuse &&
 160                     sk2->sk_state != TCP_LISTEN) {
 161                         if (!relax || (!reuseport_ok && sk->sk_reuseport &&
 162                                        sk2->sk_reuseport && reuseport_cb_ok &&
 163                                        (sk2->sk_state == TCP_TIME_WAIT ||
 164                                         uid_eq(sk_uid, sock_i_uid(sk2)))))
 165                                 return true;
 166                 } else if (!reuseport_ok || !sk->sk_reuseport ||
 167                            !sk2->sk_reuseport || !reuseport_cb_ok ||
 168                            (sk2->sk_state != TCP_TIME_WAIT &&
 169                             !uid_eq(sk_uid, sock_i_uid(sk2)))) {
 170                         return true;
 171                 }
 172         }
 173         return false;
 174 }
 175
 176 static bool __inet_bhash2_conflict(const struct sock *sk, struct sock *sk2,
 177                                    kuid_t sk_uid, bool relax,
 178                                    bool reuseport_cb_ok, bool reuseport_ok)
 179 {
 180         if (sk->sk_family == AF_INET && ipv6_only_sock(sk2))
 181                 return false;
 182
 183         return inet_bind_conflict(sk, sk2, sk_uid, relax,
 184                                   reuseport_cb_ok, reuseport_ok);
 185 }
 186
 187 static bool inet_bhash2_conflict(const struct sock *sk,
 188                                  const struct inet_bind2_bucket *tb2,
 189                                  kuid_t sk_uid,
 190                                  bool relax, bool reuseport_cb_ok,
 191                                  bool reuseport_ok)
 192 {
 193         struct inet_timewait_sock *tw2;
 194         struct sock *sk2;
 195
 196         sk_for_each_bound_bhash2(sk2, &tb2->owners) {
 197                 if (__inet_bhash2_conflict(sk, sk2, sk_uid, relax,
 198                                            reuseport_cb_ok, reuseport_ok))
 199                         return true;
 200         }
 201
 202         twsk_for_each_bound_bhash2(tw2, &tb2->deathrow) {
 203                 sk2 = (struct sock *)tw2;
 204
 205                 if (__inet_bhash2_conflict(sk, sk2, sk_uid, relax,
 206                                            reuseport_cb_ok, reuseport_ok))
 207                         return true;
 208         }
 209
 210         return false;
 211 }
 212
 213 /* This should be called only when the tb and tb2 hashbuckets' locks are held */
 214 static int inet_csk_bind_conflict(const struct sock *sk,
 215                                   const struct inet_bind_bucket *tb,
 216                                   const struct inet_bind2_bucket *tb2, /* may be null */
 217                                   bool relax, bool reuseport_ok)
 218 {
 219         bool reuseport_cb_ok;
 220         struct sock_reuseport *reuseport_cb;
 221         kuid_t uid = sock_i_uid((struct sock *)sk);
 222
 223         rcu_read_lock();
 224         reuseport_cb = rcu_dereference(sk->sk_reuseport_cb);
 225         /* paired with WRITE_ONCE() in __reuseport_(add|detach)_closed_sock */
 226         reuseport_cb_ok = !reuseport_cb || READ_ONCE(reuseport_cb->num_closed_socks);
 227         rcu_read_unlock();
 228
 229         /*
 230          * Unlike other sk lookup places we do not check
 231          * for sk_net here, since _all_ the socks listed
 232          * in tb->owners and tb2->owners list belong
 233          * to the same net - the one this bucket belongs to.
 234          */
 235
 236         if (!inet_use_bhash2_on_bind(sk)) {
 237                 struct sock *sk2;
 238
 239                 sk_for_each_bound(sk2, &tb->owners)
 240                         if (inet_bind_conflict(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         /* Conflicts with an existing IPV6_ADDR_ANY (if ipv6) or INADDR_ANY (if
 249          * ipv4) should have been checked already. We need to do these two
 250          * checks separately because their spinlocks have to be acquired/released
 251          * independently of each other, to prevent possible deadlocks
 252          */
 253         return tb2 && inet_bhash2_conflict(sk, tb2, uid, relax, reuseport_cb_ok,
 254                                            reuseport_ok);
 255 }
 256
 257 /* Determine if there is a bind conflict with an existing IPV6_ADDR_ANY (if ipv6) or
 258  * INADDR_ANY (if ipv4) socket.
 259  *
 260  * Caller must hold bhash hashbucket lock with local bh disabled, to protect
 261  * against concurrent binds on the port for addr any
 262  */
 263 static bool inet_bhash2_addr_any_conflict(const struct sock *sk, int port, int l3mdev,
 264                                           bool relax, bool reuseport_ok)
 265 {
 266         kuid_t uid = sock_i_uid((struct sock *)sk);
 267         const struct net *net = sock_net(sk);
 268         struct sock_reuseport *reuseport_cb;
 269         struct inet_bind_hashbucket *head2;
 270         struct inet_bind2_bucket *tb2;
 271         bool reuseport_cb_ok;
 272
 273         rcu_read_lock();
 274         reuseport_cb = rcu_dereference(sk->sk_reuseport_cb);
 275         /* paired with WRITE_ONCE() in __reuseport_(add|detach)_closed_sock */
 276         reuseport_cb_ok = !reuseport_cb || READ_ONCE(reuseport_cb->num_closed_socks);
 277         rcu_read_unlock();
 278
 279         head2 = inet_bhash2_addr_any_hashbucket(sk, net, port);
 280
 281         spin_lock(&head2->lock);
 282
 283         inet_bind_bucket_for_each(tb2, &head2->chain)
 284                 if (inet_bind2_bucket_match_addr_any(tb2, net, port, l3mdev, sk))
 285                         break;
 286
 287         if (tb2 && inet_bhash2_conflict(sk, tb2, uid, relax, reuseport_cb_ok,
 288                                         reuseport_ok)) {
 289                 spin_unlock(&head2->lock);
 290                 return true;
 291         }
 292
 293         spin_unlock(&head2->lock);
 294         return false;
 295 }
 296
 297 /*
 298  * Find an open port number for the socket.  Returns with the
 299  * inet_bind_hashbucket locks held if successful.
 300  */
 301 static struct inet_bind_hashbucket *
 302 inet_csk_find_open_port(const struct sock *sk, struct inet_bind_bucket **tb_ret,
 303                         struct inet_bind2_bucket **tb2_ret,
 304                         struct inet_bind_hashbucket **head2_ret, int *port_ret)
 305 {
 306         struct inet_hashinfo *hinfo = tcp_or_dccp_get_hashinfo(sk);
 307         int i, low, high, attempt_half, port, l3mdev;
 308         struct inet_bind_hashbucket *head, *head2;
 309         struct net *net = sock_net(sk);
 310         struct inet_bind2_bucket *tb2;
 311         struct inet_bind_bucket *tb;
 312         u32 remaining, offset;
 313         bool relax = false;
 314
 315         l3mdev = inet_sk_bound_l3mdev(sk);
 316 ports_exhausted:
 317         attempt_half = (sk->sk_reuse == SK_CAN_REUSE) ? 1 : 0;
 318 other_half_scan:
 319         inet_get_local_port_range(net, &low, &high);
 320         high++; /* [32768, 60999] -> [32768, 61000[ */
 321         if (high - low < 4)
 322                 attempt_half = 0;
 323         if (attempt_half) {
 324                 int half = low + (((high - low) >> 2) << 1);
 325
 326                 if (attempt_half == 1)
 327                         high = half;
 328                 else
 329                         low = half;
 330         }
 331         remaining = high - low;
 332         if (likely(remaining > 1))
 333                 remaining &= ~1U;
 334
 335         offset = get_random_u32_below(remaining);
 336         /* __inet_hash_connect() favors ports having @low parity
 337          * We do the opposite to not pollute connect() users.
 338          */
 339         offset |= 1U;
 340
 341 other_parity_scan:
 342         port = low + offset;
 343         for (i = 0; i < remaining; i += 2, port += 2) {
 344                 if (unlikely(port >= high))
 345                         port -= remaining;
 346                 if (inet_is_local_reserved_port(net, port))
 347                         continue;
 348                 head = &hinfo->bhash[inet_bhashfn(net, port,
 349                                                   hinfo->bhash_size)];
 350                 spin_lock_bh(&head->lock);
 351                 if (inet_use_bhash2_on_bind(sk)) {
 352                         if (inet_bhash2_addr_any_conflict(sk, port, l3mdev, relax, false))
 353                                 goto next_port;
 354                 }
 355
 356                 head2 = inet_bhashfn_portaddr(hinfo, sk, net, port);
 357                 spin_lock(&head2->lock);
 358                 tb2 = inet_bind2_bucket_find(head2, net, port, l3mdev, sk);
 359                 inet_bind_bucket_for_each(tb, &head->chain)
 360                         if (inet_bind_bucket_match(tb, net, port, l3mdev)) {
 361                                 if (!inet_csk_bind_conflict(sk, tb, tb2,
 362                                                             relax, false))
 363                                         goto success;
 364                                 spin_unlock(&head2->lock);
 365                                 goto next_port;
 366                         }
 367                 tb = NULL;
 368                 goto success;
 369 next_port:
 370                 spin_unlock_bh(&head->lock);
 371                 cond_resched();
 372         }
 373
 374         offset--;
 375         if (!(offset & 1))
 376                 goto other_parity_scan;
 377
 378         if (attempt_half == 1) {
 379                 /* OK we now try the upper half of the range */
 380                 attempt_half = 2;
 381                 goto other_half_scan;
 382         }
 383
 384         if (READ_ONCE(net->ipv4.sysctl_ip_autobind_reuse) && !relax) {
 385                 /* We still have a chance to connect to different destinations */
 386                 relax = true;
 387                 goto ports_exhausted;
 388         }
 389         return NULL;
 390 success:
 391         *port_ret = port;
 392         *tb_ret = tb;
 393         *tb2_ret = tb2;
 394         *head2_ret = head2;
 395         return head;
 396 }
 397
 398 static inline int sk_reuseport_match(struct inet_bind_bucket *tb,
 399                                      struct sock *sk)
 400 {
 401         kuid_t uid = sock_i_uid(sk);
 402
 403         if (tb->fastreuseport <= 0)
 404                 return 0;
 405         if (!sk->sk_reuseport)
 406                 return 0;
 407         if (rcu_access_pointer(sk->sk_reuseport_cb))
 408                 return 0;
 409         if (!uid_eq(tb->fastuid, uid))
 410                 return 0;
 411         /* We only need to check the rcv_saddr if this tb was once marked
 412          * without fastreuseport and then was reset, as we can only know that
 413          * the fast_*rcv_saddr doesn't have any conflicts with the socks on the
 414          * owners list.
 415          */
 416         if (tb->fastreuseport == FASTREUSEPORT_ANY)
 417                 return 1;
 418 #if IS_ENABLED(CONFIG_IPV6)
 419         if (tb->fast_sk_family == AF_INET6)
 420                 return ipv6_rcv_saddr_equal(&tb->fast_v6_rcv_saddr,
 421                                             inet6_rcv_saddr(sk),
 422                                             tb->fast_rcv_saddr,
 423                                             sk->sk_rcv_saddr,
 424                                             tb->fast_ipv6_only,
 425                                             ipv6_only_sock(sk), true, false);
 426 #endif
 427         return ipv4_rcv_saddr_equal(tb->fast_rcv_saddr, sk->sk_rcv_saddr,
 428                                     ipv6_only_sock(sk), true, false);
 429 }
 430
 431 void inet_csk_update_fastreuse(struct inet_bind_bucket *tb,
 432                                struct sock *sk)
 433 {
 434         kuid_t uid = sock_i_uid(sk);
 435         bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN;
 436
 437         if (hlist_empty(&tb->owners)) {
 438                 tb->fastreuse = reuse;
 439                 if (sk->sk_reuseport) {
 440                         tb->fastreuseport = FASTREUSEPORT_ANY;
 441                         tb->fastuid = uid;
 442                         tb->fast_rcv_saddr = sk->sk_rcv_saddr;
 443                         tb->fast_ipv6_only = ipv6_only_sock(sk);
 444                         tb->fast_sk_family = sk->sk_family;
 445 #if IS_ENABLED(CONFIG_IPV6)
 446                         tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
 447 #endif
 448                 } else {
 449                         tb->fastreuseport = 0;
 450                 }
 451         } else {
 452                 if (!reuse)
 453                         tb->fastreuse = 0;
 454                 if (sk->sk_reuseport) {
 455                         /* We didn't match or we don't have fastreuseport set on
 456                          * the tb, but we have sk_reuseport set on this socket
 457                          * and we know that there are no bind conflicts with
 458                          * this socket in this tb, so reset our tb's reuseport
 459                          * settings so that any subsequent sockets that match
 460                          * our current socket will be put on the fast path.
 461                          *
 462                          * If we reset we need to set FASTREUSEPORT_STRICT so we
 463                          * do extra checking for all subsequent sk_reuseport
 464                          * socks.
 465                          */
 466                         if (!sk_reuseport_match(tb, sk)) {
 467                                 tb->fastreuseport = FASTREUSEPORT_STRICT;
 468                                 tb->fastuid = uid;
 469                                 tb->fast_rcv_saddr = sk->sk_rcv_saddr;
 470                                 tb->fast_ipv6_only = ipv6_only_sock(sk);
 471                                 tb->fast_sk_family = sk->sk_family;
 472 #if IS_ENABLED(CONFIG_IPV6)
 473                                 tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
 474 #endif
 475                         }
 476                 } else {
 477                         tb->fastreuseport = 0;
 478                 }
 479         }
 480 }
 481
 482 /* Obtain a reference to a local port for the given sock,
 483  * if snum is zero it means select any available local port.
 484  * We try to allocate an odd port (and leave even ports for connect())
 485  */
 486 int inet_csk_get_port(struct sock *sk, unsigned short snum)
 487 {
 488         struct inet_hashinfo *hinfo = tcp_or_dccp_get_hashinfo(sk);
 489         bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN;
 490         bool found_port = false, check_bind_conflict = true;
 491         bool bhash_created = false, bhash2_created = false;
 492         int ret = -EADDRINUSE, port = snum, l3mdev;
 493         struct inet_bind_hashbucket *head, *head2;
 494         struct inet_bind2_bucket *tb2 = NULL;
 495         struct inet_bind_bucket *tb = NULL;
 496         bool head2_lock_acquired = false;
 497         struct net *net = sock_net(sk);
 498
 499         l3mdev = inet_sk_bound_l3mdev(sk);
 500
 501         if (!port) {
 502                 head = inet_csk_find_open_port(sk, &tb, &tb2, &head2, &port);
 503                 if (!head)
 504                         return ret;
 505
 506                 head2_lock_acquired = true;
 507
 508                 if (tb && tb2)
 509                         goto success;
 510                 found_port = true;
 511         } else {
 512                 head = &hinfo->bhash[inet_bhashfn(net, port,
 513                                                   hinfo->bhash_size)];
 514                 spin_lock_bh(&head->lock);
 515                 inet_bind_bucket_for_each(tb, &head->chain)
 516                         if (inet_bind_bucket_match(tb, net, port, l3mdev))
 517                                 break;
 518         }
 519
 520         if (!tb) {
 521                 tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep, net,
 522                                              head, port, l3mdev);
 523                 if (!tb)
 524                         goto fail_unlock;
 525                 bhash_created = true;
 526         }
 527
 528         if (!found_port) {
 529                 if (!hlist_empty(&tb->owners)) {
 530                         if (sk->sk_reuse == SK_FORCE_REUSE ||
 531                             (tb->fastreuse > 0 && reuse) ||
 532                             sk_reuseport_match(tb, sk))
 533                                 check_bind_conflict = false;
 534                 }
 535
 536                 if (check_bind_conflict && inet_use_bhash2_on_bind(sk)) {
 537                         if (inet_bhash2_addr_any_conflict(sk, port, l3mdev, true, true))
 538                                 goto fail_unlock;
 539                 }
 540
 541                 head2 = inet_bhashfn_portaddr(hinfo, sk, net, port);
 542                 spin_lock(&head2->lock);
 543                 head2_lock_acquired = true;
 544                 tb2 = inet_bind2_bucket_find(head2, net, port, l3mdev, sk);
 545         }
 546
 547         if (!tb2) {
 548                 tb2 = inet_bind2_bucket_create(hinfo->bind2_bucket_cachep,
 549                                                net, head2, port, l3mdev, sk);
 550                 if (!tb2)
 551                         goto fail_unlock;
 552                 bhash2_created = true;
 553         }
 554
 555         if (!found_port && check_bind_conflict) {
 556                 if (inet_csk_bind_conflict(sk, tb, tb2, true, true))
 557                         goto fail_unlock;
 558         }
 559
 560 success:
 561         inet_csk_update_fastreuse(tb, sk);
 562
 563         if (!inet_csk(sk)->icsk_bind_hash)
 564                 inet_bind_hash(sk, tb, tb2, port);
 565         WARN_ON(inet_csk(sk)->icsk_bind_hash != tb);
 566         WARN_ON(inet_csk(sk)->icsk_bind2_hash != tb2);
 567         ret = 0;
 568
 569 fail_unlock:
 570         if (ret) {
 571                 if (bhash_created)
 572                         inet_bind_bucket_destroy(hinfo->bind_bucket_cachep, tb);
 573                 if (bhash2_created)
 574                         inet_bind2_bucket_destroy(hinfo->bind2_bucket_cachep,
 575                                                   tb2);
 576         }
 577         if (head2_lock_acquired)
 578                 spin_unlock(&head2->lock);
 579         spin_unlock_bh(&head->lock);
 580         return ret;
 581 }
 582 EXPORT_SYMBOL_GPL(inet_csk_get_port);
 583
 584 /*
 585  * Wait for an incoming connection, avoid race conditions. This must be called
 586  * with the socket locked.
 587  */
 588 static int inet_csk_wait_for_connect(struct sock *sk, long timeo)
 589 {
 590         struct inet_connection_sock *icsk = inet_csk(sk);
 591         DEFINE_WAIT(wait);
 592         int err;
 593
 594         /*
 595          * True wake-one mechanism for incoming connections: only
 596          * one process gets woken up, not the 'whole herd'.
 597          * Since we do not 'race & poll' for established sockets
 598          * anymore, the common case will execute the loop only once.
 599          *
 600          * Subtle issue: "add_wait_queue_exclusive()" will be added
 601          * after any current non-exclusive waiters, and we know that
 602          * it will always _stay_ after any new non-exclusive waiters
 603          * because all non-exclusive waiters are added at the
 604          * beginning of the wait-queue. As such, it's ok to "drop"
 605          * our exclusiveness temporarily when we get woken up without
 606          * having to remove and re-insert us on the wait queue.
 607          */
 608         for (;;) {
 609                 prepare_to_wait_exclusive(sk_sleep(sk), &wait,
 610                                           TASK_INTERRUPTIBLE);
 611                 release_sock(sk);
 612                 if (reqsk_queue_empty(&icsk->icsk_accept_queue))
 613                         timeo = schedule_timeout(timeo);
 614                 sched_annotate_sleep();
 615                 lock_sock(sk);
 616                 err = 0;
 617                 if (!reqsk_queue_empty(&icsk->icsk_accept_queue))
 618                         break;
 619                 err = -EINVAL;
 620                 if (sk->sk_state != TCP_LISTEN)
 621                         break;
 622                 err = sock_intr_errno(timeo);
 623                 if (signal_pending(current))
 624                         break;
 625                 err = -EAGAIN;
 626                 if (!timeo)
 627                         break;
 628         }
 629         finish_wait(sk_sleep(sk), &wait);
 630         return err;
 631 }
 632
 633 /*
 634  * This will accept the next outstanding connection.
 635  */
 636 struct sock *inet_csk_accept(struct sock *sk, int flags, int *err, bool kern)
 637 {
 638         struct inet_connection_sock *icsk = inet_csk(sk);
 639         struct request_sock_queue *queue = &icsk->icsk_accept_queue;
 640         struct request_sock *req;
 641         struct sock *newsk;
 642         int error;
 643
 644         lock_sock(sk);
 645
 646         /* We need to make sure that this socket is listening,
 647          * and that it has something pending.
 648          */
 649         error = -EINVAL;
 650         if (sk->sk_state != TCP_LISTEN)
 651                 goto out_err;
 652
 653         /* Find already established connection */
 654         if (reqsk_queue_empty(queue)) {
 655                 long timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);
 656
 657                 /* If this is a non blocking socket don't sleep */
 658                 error = -EAGAIN;
 659                 if (!timeo)
 660                         goto out_err;
 661
 662                 error = inet_csk_wait_for_connect(sk, timeo);
 663                 if (error)
 664                         goto out_err;
 665         }
 666         req = reqsk_queue_remove(queue, sk);
 667         newsk = req->sk;
 668
 669         if (sk->sk_protocol == IPPROTO_TCP &&
 670             tcp_rsk(req)->tfo_listener) {
 671                 spin_lock_bh(&queue->fastopenq.lock);
 672                 if (tcp_rsk(req)->tfo_listener) {
 673                         /* We are still waiting for the final ACK from 3WHS
 674                          * so can't free req now. Instead, we set req->sk to
 675                          * NULL to signify that the child socket is taken
 676                          * so reqsk_fastopen_remove() will free the req
 677                          * when 3WHS finishes (or is aborted).
 678                          */
 679                         req->sk = NULL;
 680                         req = NULL;
 681                 }
 682                 spin_unlock_bh(&queue->fastopenq.lock);
 683         }
 684
 685 out:
 686         release_sock(sk);
 687         if (newsk && mem_cgroup_sockets_enabled) {
 688                 int amt;
 689
 690                 /* atomically get the memory usage, set and charge the
 691                  * newsk->sk_memcg.
 692                  */
 693                 lock_sock(newsk);
 694
 695                 /* The socket has not been accepted yet, no need to look at
 696                  * newsk->sk_wmem_queued.
 697                  */
 698                 amt = sk_mem_pages(newsk->sk_forward_alloc +
 699                                    atomic_read(&newsk->sk_rmem_alloc));
 700                 mem_cgroup_sk_alloc(newsk);
 701                 if (newsk->sk_memcg && amt)
 702                         mem_cgroup_charge_skmem(newsk->sk_memcg, amt,
 703                                                 GFP_KERNEL | __GFP_NOFAIL);
 704
 705                 release_sock(newsk);
 706         }
 707         if (req)
 708                 reqsk_put(req);
 709         return newsk;
 710 out_err:
 711         newsk = NULL;
 712         req = NULL;
 713         *err = error;
 714         goto out;
 715 }
 716 EXPORT_SYMBOL(inet_csk_accept);
 717
 718 /*
 719  * Using different timers for retransmit, delayed acks and probes
 720  * We may wish use just one timer maintaining a list of expire jiffies
 721  * to optimize.
 722  */
 723 void inet_csk_init_xmit_timers(struct sock *sk,
 724                                void (*retransmit_handler)(struct timer_list *t),
 725                                void (*delack_handler)(struct timer_list *t),
 726                                void (*keepalive_handler)(struct timer_list *t))
 727 {
 728         struct inet_connection_sock *icsk = inet_csk(sk);
 729
 730         timer_setup(&icsk->icsk_retransmit_timer, retransmit_handler, 0);
 731         timer_setup(&icsk->icsk_delack_timer, delack_handler, 0);
 732         timer_setup(&sk->sk_timer, keepalive_handler, 0);
 733         icsk->icsk_pending = icsk->icsk_ack.pending = 0;
 734 }
 735 EXPORT_SYMBOL(inet_csk_init_xmit_timers);
 736
 737 void inet_csk_clear_xmit_timers(struct sock *sk)
 738 {
 739         struct inet_connection_sock *icsk = inet_csk(sk);
 740
 741         icsk->icsk_pending = icsk->icsk_ack.pending = 0;
 742
 743         sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
 744         sk_stop_timer(sk, &icsk->icsk_delack_timer);
 745         sk_stop_timer(sk, &sk->sk_timer);
 746 }
 747 EXPORT_SYMBOL(inet_csk_clear_xmit_timers);
 748
 749 void inet_csk_delete_keepalive_timer(struct sock *sk)
 750 {
 751         sk_stop_timer(sk, &sk->sk_timer);
 752 }
 753 EXPORT_SYMBOL(inet_csk_delete_keepalive_timer);
 754
 755 void inet_csk_reset_keepalive_timer(struct sock *sk, unsigned long len)
 756 {
 757         sk_reset_timer(sk, &sk->sk_timer, jiffies + len);
 758 }
 759 EXPORT_SYMBOL(inet_csk_reset_keepalive_timer);
 760
 761 struct dst_entry *inet_csk_route_req(const struct sock *sk,
 762                                      struct flowi4 *fl4,
 763                                      const struct request_sock *req)
 764 {
 765         const struct inet_request_sock *ireq = inet_rsk(req);
 766         struct net *net = read_pnet(&ireq->ireq_net);
 767         struct ip_options_rcu *opt;
 768         struct rtable *rt;
 769
 770         rcu_read_lock();
 771         opt = rcu_dereference(ireq->ireq_opt);
 772
 773         flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
 774                            RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
 775                            sk->sk_protocol, inet_sk_flowi_flags(sk),
 776                            (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
 777                            ireq->ir_loc_addr, ireq->ir_rmt_port,
 778                            htons(ireq->ir_num), sk->sk_uid);
 779         security_req_classify_flow(req, flowi4_to_flowi_common(fl4));
 780         rt = ip_route_output_flow(net, fl4, sk);
 781         if (IS_ERR(rt))
 782                 goto no_route;
 783         if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
 784                 goto route_err;
 785         rcu_read_unlock();
 786         return &rt->dst;
 787
 788 route_err:
 789         ip_rt_put(rt);
 790 no_route:
 791         rcu_read_unlock();
 792         __IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
 793         return NULL;
 794 }
 795 EXPORT_SYMBOL_GPL(inet_csk_route_req);
 796
 797 struct dst_entry *inet_csk_route_child_sock(const struct sock *sk,
 798                                             struct sock *newsk,
 799                                             const struct request_sock *req)
 800 {
 801         const struct inet_request_sock *ireq = inet_rsk(req);
 802         struct net *net = read_pnet(&ireq->ireq_net);
 803         struct inet_sock *newinet = inet_sk(newsk);
 804         struct ip_options_rcu *opt;
 805         struct flowi4 *fl4;
 806         struct rtable *rt;
 807
 808         opt = rcu_dereference(ireq->ireq_opt);
 809         fl4 = &newinet->cork.fl.u.ip4;
 810
 811         flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
 812                            RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
 813                            sk->sk_protocol, inet_sk_flowi_flags(sk),
 814                            (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
 815                            ireq->ir_loc_addr, ireq->ir_rmt_port,
 816                            htons(ireq->ir_num), sk->sk_uid);
 817         security_req_classify_flow(req, flowi4_to_flowi_common(fl4));
 818         rt = ip_route_output_flow(net, fl4, sk);
 819         if (IS_ERR(rt))
 820                 goto no_route;
 821         if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
 822                 goto route_err;
 823         return &rt->dst;
 824
 825 route_err:
 826         ip_rt_put(rt);
 827 no_route:
 828         __IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
 829         return NULL;
 830 }
 831 EXPORT_SYMBOL_GPL(inet_csk_route_child_sock);
 832
 833 /* Decide when to expire the request and when to resend SYN-ACK */
 834 static void syn_ack_recalc(struct request_sock *req,
 835                            const int max_syn_ack_retries,
 836                            const u8 rskq_defer_accept,
 837                            int *expire, int *resend)
 838 {
 839         if (!rskq_defer_accept) {
 840                 *expire = req->num_timeout >= max_syn_ack_retries;
 841                 *resend = 1;
 842                 return;
 843         }
 844         *expire = req->num_timeout >= max_syn_ack_retries &&
 845                   (!inet_rsk(req)->acked || req->num_timeout >= rskq_defer_accept);
 846         /* Do not resend while waiting for data after ACK,
 847          * start to resend on end of deferring period to give
 848          * last chance for data or ACK to create established socket.
 849          */
 850         *resend = !inet_rsk(req)->acked ||
 851                   req->num_timeout >= rskq_defer_accept - 1;
 852 }
 853
 854 int inet_rtx_syn_ack(const struct sock *parent, struct request_sock *req)
 855 {
 856         int err = req->rsk_ops->rtx_syn_ack(parent, req);
 857
 858         if (!err)
 859                 req->num_retrans++;
 860         return err;
 861 }
 862 EXPORT_SYMBOL(inet_rtx_syn_ack);
 863
 864 static struct request_sock *inet_reqsk_clone(struct request_sock *req,
 865                                              struct sock *sk)
 866 {
 867         struct sock *req_sk, *nreq_sk;
 868         struct request_sock *nreq;
 869
 870         nreq = kmem_cache_alloc(req->rsk_ops->slab, GFP_ATOMIC | __GFP_NOWARN);
 871         if (!nreq) {
 872                 __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQFAILURE);
 873
 874                 /* paired with refcount_inc_not_zero() in reuseport_migrate_sock() */
 875                 sock_put(sk);
 876                 return NULL;
 877         }
 878
 879         req_sk = req_to_sk(req);
 880         nreq_sk = req_to_sk(nreq);
 881
 882         memcpy(nreq_sk, req_sk,
 883                offsetof(struct sock, sk_dontcopy_begin));
 884         memcpy(&nreq_sk->sk_dontcopy_end, &req_sk->sk_dontcopy_end,
 885                req->rsk_ops->obj_size - offsetof(struct sock, sk_dontcopy_end));
 886
 887         sk_node_init(&nreq_sk->sk_node);
 888         nreq_sk->sk_tx_queue_mapping = req_sk->sk_tx_queue_mapping;
 889 #ifdef CONFIG_SOCK_RX_QUEUE_MAPPING
 890         nreq_sk->sk_rx_queue_mapping = req_sk->sk_rx_queue_mapping;
 891 #endif
 892         nreq_sk->sk_incoming_cpu = req_sk->sk_incoming_cpu;
 893
 894         nreq->rsk_listener = sk;
 895
 896         /* We need not acquire fastopenq->lock
 897          * because the child socket is locked in inet_csk_listen_stop().
 898          */
 899         if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(nreq)->tfo_listener)
 900                 rcu_assign_pointer(tcp_sk(nreq->sk)->fastopen_rsk, nreq);
 901
 902         return nreq;
 903 }
 904
 905 static void reqsk_queue_migrated(struct request_sock_queue *queue,
 906                                  const struct request_sock *req)
 907 {
 908         if (req->num_timeout == 0)
 909                 atomic_inc(&queue->young);
 910         atomic_inc(&queue->qlen);
 911 }
 912
 913 static void reqsk_migrate_reset(struct request_sock *req)
 914 {
 915         req->saved_syn = NULL;
 916 #if IS_ENABLED(CONFIG_IPV6)
 917         inet_rsk(req)->ipv6_opt = NULL;
 918         inet_rsk(req)->pktopts = NULL;
 919 #else
 920         inet_rsk(req)->ireq_opt = NULL;
 921 #endif
 922 }
 923
 924 /* return true if req was found in the ehash table */
 925 static bool reqsk_queue_unlink(struct request_sock *req)
 926 {
 927         struct sock *sk = req_to_sk(req);
 928         bool found = false;
 929
 930         if (sk_hashed(sk)) {
 931                 struct inet_hashinfo *hashinfo = tcp_or_dccp_get_hashinfo(sk);
 932                 spinlock_t *lock = inet_ehash_lockp(hashinfo, req->rsk_hash);
 933
 934                 spin_lock(lock);
 935                 found = __sk_nulls_del_node_init_rcu(sk);
 936                 spin_unlock(lock);
 937         }
 938         if (timer_pending(&req->rsk_timer) && del_timer_sync(&req->rsk_timer))
 939                 reqsk_put(req);
 940         return found;
 941 }
 942
 943 bool inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req)
 944 {
 945         bool unlinked = reqsk_queue_unlink(req);
 946
 947         if (unlinked) {
 948                 reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req);
 949                 reqsk_put(req);
 950         }
 951         return unlinked;
 952 }
 953 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop);
 954
 955 void inet_csk_reqsk_queue_drop_and_put(struct sock *sk, struct request_sock *req)
 956 {
 957         inet_csk_reqsk_queue_drop(sk, req);
 958         reqsk_put(req);
 959 }
 960 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop_and_put);
 961
 962 static void reqsk_timer_handler(struct timer_list *t)
 963 {
 964         struct request_sock *req = from_timer(req, t, rsk_timer);
 965         struct request_sock *nreq = NULL, *oreq = req;
 966         struct sock *sk_listener = req->rsk_listener;
 967         struct inet_connection_sock *icsk;
 968         struct request_sock_queue *queue;
 969         struct net *net;
 970         int max_syn_ack_retries, qlen, expire = 0, resend = 0;
 971
 972         if (inet_sk_state_load(sk_listener) != TCP_LISTEN) {
 973                 struct sock *nsk;
 974
 975                 nsk = reuseport_migrate_sock(sk_listener, req_to_sk(req), NULL);
 976                 if (!nsk)
 977                         goto drop;
 978
 979                 nreq = inet_reqsk_clone(req, nsk);
 980                 if (!nreq)
 981                         goto drop;
 982
 983                 /* The new timer for the cloned req can decrease the 2
 984                  * by calling inet_csk_reqsk_queue_drop_and_put(), so
 985                  * hold another count to prevent use-after-free and
 986                  * call reqsk_put() just before return.
 987                  */
 988                 refcount_set(&nreq->rsk_refcnt, 2 + 1);
 989                 timer_setup(&nreq->rsk_timer, reqsk_timer_handler, TIMER_PINNED);
 990                 reqsk_queue_migrated(&inet_csk(nsk)->icsk_accept_queue, req);
 991
 992                 req = nreq;
 993                 sk_listener = nsk;
 994         }
 995
 996         icsk = inet_csk(sk_listener);
 997         net = sock_net(sk_listener);
 998         max_syn_ack_retries = icsk->icsk_syn_retries ? :
 999                 READ_ONCE(net->ipv4.sysctl_tcp_synack_retries);
1000         /* Normally all the openreqs are young and become mature
1001          * (i.e. converted to established socket) for first timeout.
1002          * If synack was not acknowledged for 1 second, it means
1003          * one of the following things: synack was lost, ack was lost,
1004          * rtt is high or nobody planned to ack (i.e. synflood).
1005          * When server is a bit loaded, queue is populated with old
1006          * open requests, reducing effective size of queue.
1007          * When server is well loaded, queue size reduces to zero
1008          * after several minutes of work. It is not synflood,
1009          * it is normal operation. The solution is pruning
1010          * too old entries overriding normal timeout, when
1011          * situation becomes dangerous.
1012          *
1013          * Essentially, we reserve half of room for young
1014          * embrions; and abort old ones without pity, if old
1015          * ones are about to clog our table.
1016          */
1017         queue = &icsk->icsk_accept_queue;
1018         qlen = reqsk_queue_len(queue);
1019         if ((qlen << 1) > max(8U, READ_ONCE(sk_listener->sk_max_ack_backlog))) {
1020                 int young = reqsk_queue_len_young(queue) << 1;
1021
1022                 while (max_syn_ack_retries > 2) {
1023                         if (qlen < young)
1024                                 break;
1025                         max_syn_ack_retries--;
1026                         young <<= 1;
1027                 }
1028         }
1029         syn_ack_recalc(req, max_syn_ack_retries, READ_ONCE(queue->rskq_defer_accept),
1030                        &expire, &resend);
1031         req->rsk_ops->syn_ack_timeout(req);
1032         if (!expire &&
1033             (!resend ||
1034              !inet_rtx_syn_ack(sk_listener, req) ||
1035              inet_rsk(req)->acked)) {
1036                 if (req->num_timeout++ == 0)
1037                         atomic_dec(&queue->young);
1038                 mod_timer(&req->rsk_timer, jiffies + reqsk_timeout(req, TCP_RTO_MAX));
1039
1040                 if (!nreq)
1041                         return;
1042
1043                 if (!inet_ehash_insert(req_to_sk(nreq), req_to_sk(oreq), NULL)) {
1044                         /* delete timer */
1045                         inet_csk_reqsk_queue_drop(sk_listener, nreq);
1046                         goto no_ownership;
1047                 }
1048
1049                 __NET_INC_STATS(net, LINUX_MIB_TCPMIGRATEREQSUCCESS);
1050                 reqsk_migrate_reset(oreq);
1051                 reqsk_queue_removed(&inet_csk(oreq->rsk_listener)->icsk_accept_queue, oreq);
1052                 reqsk_put(oreq);
1053
1054                 reqsk_put(nreq);
1055                 return;
1056         }
1057
1058         /* Even if we can clone the req, we may need not retransmit any more
1059          * SYN+ACKs (nreq->num_timeout > max_syn_ack_retries, etc), or another
1060          * CPU may win the "own_req" race so that inet_ehash_insert() fails.
1061          */
1062         if (nreq) {
1063                 __NET_INC_STATS(net, LINUX_MIB_TCPMIGRATEREQFAILURE);
1064 no_ownership:
1065                 reqsk_migrate_reset(nreq);
1066                 reqsk_queue_removed(queue, nreq);
1067                 __reqsk_free(nreq);
1068         }
1069
1070 drop:
1071         inet_csk_reqsk_queue_drop_and_put(oreq->rsk_listener, oreq);
1072 }
1073
1074 static void reqsk_queue_hash_req(struct request_sock *req,
1075                                  unsigned long timeout)
1076 {
1077         timer_setup(&req->rsk_timer, reqsk_timer_handler, TIMER_PINNED);
1078         mod_timer(&req->rsk_timer, jiffies + timeout);
1079
1080         inet_ehash_insert(req_to_sk(req), NULL, NULL);
1081         /* before letting lookups find us, make sure all req fields
1082          * are committed to memory and refcnt initialized.
1083          */
1084         smp_wmb();
1085         refcount_set(&req->rsk_refcnt, 2 + 1);
1086 }
1087
1088 void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
1089                                    unsigned long timeout)
1090 {
1091         reqsk_queue_hash_req(req, timeout);
1092         inet_csk_reqsk_queue_added(sk);
1093 }
1094 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add);
1095
1096 static void inet_clone_ulp(const struct request_sock *req, struct sock *newsk,
1097                            const gfp_t priority)
1098 {
1099         struct inet_connection_sock *icsk = inet_csk(newsk);
1100
1101         if (!icsk->icsk_ulp_ops)
1102                 return;
1103
1104         if (icsk->icsk_ulp_ops->clone)
1105                 icsk->icsk_ulp_ops->clone(req, newsk, priority);
1106 }
1107
1108 /**
1109  *      inet_csk_clone_lock - clone an inet socket, and lock its clone
1110  *      @sk: the socket to clone
1111  *      @req: request_sock
1112  *      @priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc)
1113  *
1114  *      Caller must unlock socket even in error path (bh_unlock_sock(newsk))
1115  */
1116 struct sock *inet_csk_clone_lock(const struct sock *sk,
1117                                  const struct request_sock *req,
1118                                  const gfp_t priority)
1119 {
1120         struct sock *newsk = sk_clone_lock(sk, priority);
1121
1122         if (newsk) {
1123                 struct inet_connection_sock *newicsk = inet_csk(newsk);
1124
1125                 inet_sk_set_state(newsk, TCP_SYN_RECV);
1126                 newicsk->icsk_bind_hash = NULL;
1127                 newicsk->icsk_bind2_hash = NULL;
1128
1129                 inet_sk(newsk)->inet_dport = inet_rsk(req)->ir_rmt_port;
1130                 inet_sk(newsk)->inet_num = inet_rsk(req)->ir_num;
1131                 inet_sk(newsk)->inet_sport = htons(inet_rsk(req)->ir_num);
1132
1133                 /* listeners have SOCK_RCU_FREE, not the children */
1134                 sock_reset_flag(newsk, SOCK_RCU_FREE);
1135
1136                 inet_sk(newsk)->mc_list = NULL;
1137
1138                 newsk->sk_mark = inet_rsk(req)->ir_mark;
1139                 atomic64_set(&newsk->sk_cookie,
1140                              atomic64_read(&inet_rsk(req)->ir_cookie));
1141
1142                 newicsk->icsk_retransmits = 0;
1143                 newicsk->icsk_backoff     = 0;
1144                 newicsk->icsk_probes_out  = 0;
1145                 newicsk->icsk_probes_tstamp = 0;
1146
1147                 /* Deinitialize accept_queue to trap illegal accesses. */
1148                 memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue));
1149
1150                 inet_clone_ulp(req, newsk, priority);
1151
1152                 security_inet_csk_clone(newsk, req);
1153         }
1154         return newsk;
1155 }
1156 EXPORT_SYMBOL_GPL(inet_csk_clone_lock);
1157
1158 /*
1159  * At this point, there should be no process reference to this
1160  * socket, and thus no user references at all.  Therefore we
1161  * can assume the socket waitqueue is inactive and nobody will
1162  * try to jump onto it.
1163  */
1164 void inet_csk_destroy_sock(struct sock *sk)
1165 {
1166         WARN_ON(sk->sk_state != TCP_CLOSE);
1167         WARN_ON(!sock_flag(sk, SOCK_DEAD));
1168
1169         /* It cannot be in hash table! */
1170         WARN_ON(!sk_unhashed(sk));
1171
1172         /* If it has not 0 inet_sk(sk)->inet_num, it must be bound */
1173         WARN_ON(inet_sk(sk)->inet_num && !inet_csk(sk)->icsk_bind_hash);
1174
1175         sk->sk_prot->destroy(sk);
1176
1177         sk_stream_kill_queues(sk);
1178
1179         xfrm_sk_free_policy(sk);
1180
1181         sk_refcnt_debug_release(sk);
1182
1183         this_cpu_dec(*sk->sk_prot->orphan_count);
1184
1185         sock_put(sk);
1186 }
1187 EXPORT_SYMBOL(inet_csk_destroy_sock);
1188
1189 /* This function allows to force a closure of a socket after the call to
1190  * tcp/dccp_create_openreq_child().
1191  */
1192 void inet_csk_prepare_forced_close(struct sock *sk)
1193         __releases(&sk->sk_lock.slock)
1194 {
1195         /* sk_clone_lock locked the socket and set refcnt to 2 */
1196         bh_unlock_sock(sk);
1197         sock_put(sk);
1198         inet_csk_prepare_for_destroy_sock(sk);
1199         inet_sk(sk)->inet_num = 0;
1200 }
1201 EXPORT_SYMBOL(inet_csk_prepare_forced_close);
1202
1203 int inet_csk_listen_start(struct sock *sk)
1204 {
1205         struct inet_connection_sock *icsk = inet_csk(sk);
1206         struct inet_sock *inet = inet_sk(sk);
1207         int err;
1208
1209         reqsk_queue_alloc(&icsk->icsk_accept_queue);
1210
1211         sk->sk_ack_backlog = 0;
1212         inet_csk_delack_init(sk);
1213
1214         if (sk->sk_txrehash == SOCK_TXREHASH_DEFAULT)
1215                 sk->sk_txrehash = READ_ONCE(sock_net(sk)->core.sysctl_txrehash);
1216
1217         /* There is race window here: we announce ourselves listening,
1218          * but this transition is still not validated by get_port().
1219          * It is OK, because this socket enters to hash table only
1220          * after validation is complete.
1221          */
1222         inet_sk_state_store(sk, TCP_LISTEN);
1223         err = sk->sk_prot->get_port(sk, inet->inet_num);
1224         if (!err) {
1225                 inet->inet_sport = htons(inet->inet_num);
1226
1227                 sk_dst_reset(sk);
1228                 err = sk->sk_prot->hash(sk);
1229
1230                 if (likely(!err))
1231                         return 0;
1232         }
1233
1234         inet_sk_set_state(sk, TCP_CLOSE);
1235         return err;
1236 }
1237 EXPORT_SYMBOL_GPL(inet_csk_listen_start);
1238
1239 static void inet_child_forget(struct sock *sk, struct request_sock *req,
1240                               struct sock *child)
1241 {
1242         sk->sk_prot->disconnect(child, O_NONBLOCK);
1243
1244         sock_orphan(child);
1245
1246         this_cpu_inc(*sk->sk_prot->orphan_count);
1247
1248         if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(req)->tfo_listener) {
1249                 BUG_ON(rcu_access_pointer(tcp_sk(child)->fastopen_rsk) != req);
1250                 BUG_ON(sk != req->rsk_listener);
1251
1252                 /* Paranoid, to prevent race condition if
1253                  * an inbound pkt destined for child is
1254                  * blocked by sock lock in tcp_v4_rcv().
1255                  * Also to satisfy an assertion in
1256                  * tcp_v4_destroy_sock().
1257                  */
1258                 RCU_INIT_POINTER(tcp_sk(child)->fastopen_rsk, NULL);
1259         }
1260         inet_csk_destroy_sock(child);
1261 }
1262
1263 struct sock *inet_csk_reqsk_queue_add(struct sock *sk,
1264                                       struct request_sock *req,
1265                                       struct sock *child)
1266 {
1267         struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
1268
1269         spin_lock(&queue->rskq_lock);
1270         if (unlikely(sk->sk_state != TCP_LISTEN)) {
1271                 inet_child_forget(sk, req, child);
1272                 child = NULL;
1273         } else {
1274                 req->sk = child;
1275                 req->dl_next = NULL;
1276                 if (queue->rskq_accept_head == NULL)
1277                         WRITE_ONCE(queue->rskq_accept_head, req);
1278                 else
1279                         queue->rskq_accept_tail->dl_next = req;
1280                 queue->rskq_accept_tail = req;
1281                 sk_acceptq_added(sk);
1282         }
1283         spin_unlock(&queue->rskq_lock);
1284         return child;
1285 }
1286 EXPORT_SYMBOL(inet_csk_reqsk_queue_add);
1287
1288 struct sock *inet_csk_complete_hashdance(struct sock *sk, struct sock *child,
1289                                          struct request_sock *req, bool own_req)
1290 {
1291         if (own_req) {
1292                 inet_csk_reqsk_queue_drop(req->rsk_listener, req);
1293                 reqsk_queue_removed(&inet_csk(req->rsk_listener)->icsk_accept_queue, req);
1294
1295                 if (sk != req->rsk_listener) {
1296                         /* another listening sk has been selected,
1297                          * migrate the req to it.
1298                          */
1299                         struct request_sock *nreq;
1300
1301                         /* hold a refcnt for the nreq->rsk_listener
1302                          * which is assigned in inet_reqsk_clone()
1303                          */
1304                         sock_hold(sk);
1305                         nreq = inet_reqsk_clone(req, sk);
1306                         if (!nreq) {
1307                                 inet_child_forget(sk, req, child);
1308                                 goto child_put;
1309                         }
1310
1311                         refcount_set(&nreq->rsk_refcnt, 1);
1312                         if (inet_csk_reqsk_queue_add(sk, nreq, child)) {
1313                                 __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQSUCCESS);
1314                                 reqsk_migrate_reset(req);
1315                                 reqsk_put(req);
1316                                 return child;
1317                         }
1318
1319                         __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQFAILURE);
1320                         reqsk_migrate_reset(nreq);
1321                         __reqsk_free(nreq);
1322                 } else if (inet_csk_reqsk_queue_add(sk, req, child)) {
1323                         return child;
1324                 }
1325         }
1326         /* Too bad, another child took ownership of the request, undo. */
1327 child_put:
1328         bh_unlock_sock(child);
1329         sock_put(child);
1330         return NULL;
1331 }
1332 EXPORT_SYMBOL(inet_csk_complete_hashdance);
1333
1334 /*
1335  *      This routine closes sockets which have been at least partially
1336  *      opened, but not yet accepted.
1337  */
1338 void inet_csk_listen_stop(struct sock *sk)
1339 {
1340         struct inet_connection_sock *icsk = inet_csk(sk);
1341         struct request_sock_queue *queue = &icsk->icsk_accept_queue;
1342         struct request_sock *next, *req;
1343
1344         /* Following specs, it would be better either to send FIN
1345          * (and enter FIN-WAIT-1, it is normal close)
1346          * or to send active reset (abort).
1347          * Certainly, it is pretty dangerous while synflood, but it is
1348          * bad justification for our negligence 8)
1349          * To be honest, we are not able to make either
1350          * of the variants now.                 --ANK
1351          */
1352         while ((req = reqsk_queue_remove(queue, sk)) != NULL) {
1353                 struct sock *child = req->sk, *nsk;
1354                 struct request_sock *nreq;
1355
1356                 local_bh_disable();
1357                 bh_lock_sock(child);
1358                 WARN_ON(sock_owned_by_user(child));
1359                 sock_hold(child);
1360
1361                 nsk = reuseport_migrate_sock(sk, child, NULL);
1362                 if (nsk) {
1363                         nreq = inet_reqsk_clone(req, nsk);
1364                         if (nreq) {
1365                                 refcount_set(&nreq->rsk_refcnt, 1);
1366
1367                                 if (inet_csk_reqsk_queue_add(nsk, nreq, child)) {
1368                                         __NET_INC_STATS(sock_net(nsk),
1369                                                         LINUX_MIB_TCPMIGRATEREQSUCCESS);
1370                                         reqsk_migrate_reset(req);
1371                                 } else {
1372                                         __NET_INC_STATS(sock_net(nsk),
1373                                                         LINUX_MIB_TCPMIGRATEREQFAILURE);
1374                                         reqsk_migrate_reset(nreq);
1375                                         __reqsk_free(nreq);
1376                                 }
1377
1378                                 /* inet_csk_reqsk_queue_add() has already
1379                                  * called inet_child_forget() on failure case.
1380                                  */
1381                                 goto skip_child_forget;
1382                         }
1383                 }
1384
1385                 inet_child_forget(sk, req, child);
1386 skip_child_forget:
1387                 reqsk_put(req);
1388                 bh_unlock_sock(child);
1389                 local_bh_enable();
1390                 sock_put(child);
1391
1392                 cond_resched();
1393         }
1394         if (queue->fastopenq.rskq_rst_head) {
1395                 /* Free all the reqs queued in rskq_rst_head. */
1396                 spin_lock_bh(&queue->fastopenq.lock);
1397                 req = queue->fastopenq.rskq_rst_head;
1398                 queue->fastopenq.rskq_rst_head = NULL;
1399                 spin_unlock_bh(&queue->fastopenq.lock);
1400                 while (req != NULL) {
1401                         next = req->dl_next;
1402                         reqsk_put(req);
1403                         req = next;
1404                 }
1405         }
1406         WARN_ON_ONCE(sk->sk_ack_backlog);
1407 }
1408 EXPORT_SYMBOL_GPL(inet_csk_listen_stop);
1409
1410 void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr)
1411 {
1412         struct sockaddr_in *sin = (struct sockaddr_in *)uaddr;
1413         const struct inet_sock *inet = inet_sk(sk);
1414
1415         sin->sin_family         = AF_INET;
1416         sin->sin_addr.s_addr    = inet->inet_daddr;
1417         sin->sin_port           = inet->inet_dport;
1418 }
1419 EXPORT_SYMBOL_GPL(inet_csk_addr2sockaddr);
1420
1421 static struct dst_entry *inet_csk_rebuild_route(struct sock *sk, struct flowi *fl)
1422 {
1423         const struct inet_sock *inet = inet_sk(sk);
1424         const struct ip_options_rcu *inet_opt;
1425         __be32 daddr = inet->inet_daddr;
1426         struct flowi4 *fl4;
1427         struct rtable *rt;
1428
1429         rcu_read_lock();
1430         inet_opt = rcu_dereference(inet->inet_opt);
1431         if (inet_opt && inet_opt->opt.srr)
1432                 daddr = inet_opt->opt.faddr;
1433         fl4 = &fl->u.ip4;
1434         rt = ip_route_output_ports(sock_net(sk), fl4, sk, daddr,
1435                                    inet->inet_saddr, inet->inet_dport,
1436                                    inet->inet_sport, sk->sk_protocol,
1437                                    RT_CONN_FLAGS(sk), sk->sk_bound_dev_if);
1438         if (IS_ERR(rt))
1439                 rt = NULL;
1440         if (rt)
1441                 sk_setup_caps(sk, &rt->dst);
1442         rcu_read_unlock();
1443
1444         return &rt->dst;
1445 }
1446
1447 struct dst_entry *inet_csk_update_pmtu(struct sock *sk, u32 mtu)
1448 {
1449         struct dst_entry *dst = __sk_dst_check(sk, 0);
1450         struct inet_sock *inet = inet_sk(sk);
1451
1452         if (!dst) {
1453                 dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
1454                 if (!dst)
1455                         goto out;
1456         }
1457         dst->ops->update_pmtu(dst, sk, NULL, mtu, true);
1458
1459         dst = __sk_dst_check(sk, 0);
1460         if (!dst)
1461                 dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
1462 out:
1463         return dst;
1464 }
1465 EXPORT_SYMBOL_GPL(inet_csk_update_pmtu);