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 /**
 121  *      inet_sk_get_local_port_range - fetch ephemeral ports range
 122  *      @sk: socket
 123  *      @low: pointer to low port
 124  *      @high: pointer to high port
 125  *
 126  *      Fetch netns port range (/proc/sys/net/ipv4/ip_local_port_range)
 127  *      Range can be overridden if socket got IP_LOCAL_PORT_RANGE option.
 128  *      Returns true if IP_LOCAL_PORT_RANGE was set on this socket.
 129  */
 130 bool inet_sk_get_local_port_range(const struct sock *sk, int *low, int *high)
 131 {
 132         int lo, hi, sk_lo, sk_hi;
 133         bool local_range = false;
 134         u32 sk_range;
 135
 136         inet_get_local_port_range(sock_net(sk), &lo, &hi);
 137
 138         sk_range = READ_ONCE(inet_sk(sk)->local_port_range);
 139         if (unlikely(sk_range)) {
 140                 sk_lo = sk_range & 0xffff;
 141                 sk_hi = sk_range >> 16;
 142
 143                 if (lo <= sk_lo && sk_lo <= hi)
 144                         lo = sk_lo;
 145                 if (lo <= sk_hi && sk_hi <= hi)
 146                         hi = sk_hi;
 147                 local_range = true;
 148         }
 149
 150         *low = lo;
 151         *high = hi;
 152         return local_range;
 153 }
 154 EXPORT_SYMBOL(inet_sk_get_local_port_range);
 155
 156 static bool inet_use_bhash2_on_bind(const struct sock *sk)
 157 {
 158 #if IS_ENABLED(CONFIG_IPV6)
 159         if (sk->sk_family == AF_INET6) {
 160                 int addr_type = ipv6_addr_type(&sk->sk_v6_rcv_saddr);
 161
 162                 if (addr_type == IPV6_ADDR_ANY)
 163                         return false;
 164
 165                 if (addr_type != IPV6_ADDR_MAPPED)
 166                         return true;
 167         }
 168 #endif
 169         return sk->sk_rcv_saddr != htonl(INADDR_ANY);
 170 }
 171
 172 static bool inet_bind_conflict(const struct sock *sk, struct sock *sk2,
 173                                kuid_t sk_uid, bool relax,
 174                                bool reuseport_cb_ok, bool reuseport_ok)
 175 {
 176         int bound_dev_if2;
 177
 178         if (sk == sk2)
 179                 return false;
 180
 181         bound_dev_if2 = READ_ONCE(sk2->sk_bound_dev_if);
 182
 183         if (!sk->sk_bound_dev_if || !bound_dev_if2 ||
 184             sk->sk_bound_dev_if == bound_dev_if2) {
 185                 if (sk->sk_reuse && sk2->sk_reuse &&
 186                     sk2->sk_state != TCP_LISTEN) {
 187                         if (!relax || (!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                 } else if (!reuseport_ok || !sk->sk_reuseport ||
 193                            !sk2->sk_reuseport || !reuseport_cb_ok ||
 194                            (sk2->sk_state != TCP_TIME_WAIT &&
 195                             !uid_eq(sk_uid, sock_i_uid(sk2)))) {
 196                         return true;
 197                 }
 198         }
 199         return false;
 200 }
 201
 202 static bool __inet_bhash2_conflict(const struct sock *sk, struct sock *sk2,
 203                                    kuid_t sk_uid, bool relax,
 204                                    bool reuseport_cb_ok, bool reuseport_ok)
 205 {
 206         if (ipv6_only_sock(sk2)) {
 207                 if (sk->sk_family == AF_INET)
 208                         return false;
 209
 210 #if IS_ENABLED(CONFIG_IPV6)
 211                 if (ipv6_addr_v4mapped(&sk->sk_v6_rcv_saddr))
 212                         return false;
 213 #endif
 214         }
 215
 216         return inet_bind_conflict(sk, sk2, sk_uid, relax,
 217                                   reuseport_cb_ok, reuseport_ok);
 218 }
 219
 220 static bool inet_bhash2_conflict(const struct sock *sk,
 221                                  const struct inet_bind2_bucket *tb2,
 222                                  kuid_t sk_uid,
 223                                  bool relax, bool reuseport_cb_ok,
 224                                  bool reuseport_ok)
 225 {
 226         struct sock *sk2;
 227
 228         sk_for_each_bound(sk2, &tb2->owners) {
 229                 if (__inet_bhash2_conflict(sk, sk2, sk_uid, relax,
 230                                            reuseport_cb_ok, reuseport_ok))
 231                         return true;
 232         }
 233
 234         return false;
 235 }
 236
 237 #define sk_for_each_bound_bhash(__sk, __tb2, __tb)                      \
 238         hlist_for_each_entry(__tb2, &(__tb)->bhash2, bhash_node)        \
 239                 sk_for_each_bound((__sk), &(__tb2)->owners)
 240
 241 /* This should be called only when the tb and tb2 hashbuckets' locks are held */
 242 static int inet_csk_bind_conflict(const struct sock *sk,
 243                                   const struct inet_bind_bucket *tb,
 244                                   const struct inet_bind2_bucket *tb2, /* may be null */
 245                                   bool relax, bool reuseport_ok)
 246 {
 247         kuid_t uid = sock_i_uid((struct sock *)sk);
 248         struct sock_reuseport *reuseport_cb;
 249         bool reuseport_cb_ok;
 250         struct sock *sk2;
 251
 252         rcu_read_lock();
 253         reuseport_cb = rcu_dereference(sk->sk_reuseport_cb);
 254         /* paired with WRITE_ONCE() in __reuseport_(add|detach)_closed_sock */
 255         reuseport_cb_ok = !reuseport_cb || READ_ONCE(reuseport_cb->num_closed_socks);
 256         rcu_read_unlock();
 257
 258         /* Conflicts with an existing IPV6_ADDR_ANY (if ipv6) or INADDR_ANY (if
 259          * ipv4) should have been checked already. We need to do these two
 260          * checks separately because their spinlocks have to be acquired/released
 261          * independently of each other, to prevent possible deadlocks
 262          */
 263         if (inet_use_bhash2_on_bind(sk))
 264                 return tb2 && inet_bhash2_conflict(sk, tb2, uid, relax,
 265                                                    reuseport_cb_ok, reuseport_ok);
 266
 267         /* Unlike other sk lookup places we do not check
 268          * for sk_net here, since _all_ the socks listed
 269          * in tb->owners and tb2->owners list belong
 270          * to the same net - the one this bucket belongs to.
 271          */
 272         sk_for_each_bound_bhash(sk2, tb2, tb) {
 273                 if (!inet_bind_conflict(sk, sk2, uid, relax, reuseport_cb_ok, reuseport_ok))
 274                         continue;
 275
 276                 if (inet_rcv_saddr_equal(sk, sk2, true))
 277                         return true;
 278         }
 279
 280         return false;
 281 }
 282
 283 /* Determine if there is a bind conflict with an existing IPV6_ADDR_ANY (if ipv6) or
 284  * INADDR_ANY (if ipv4) socket.
 285  *
 286  * Caller must hold bhash hashbucket lock with local bh disabled, to protect
 287  * against concurrent binds on the port for addr any
 288  */
 289 static bool inet_bhash2_addr_any_conflict(const struct sock *sk, int port, int l3mdev,
 290                                           bool relax, bool reuseport_ok)
 291 {
 292         kuid_t uid = sock_i_uid((struct sock *)sk);
 293         const struct net *net = sock_net(sk);
 294         struct sock_reuseport *reuseport_cb;
 295         struct inet_bind_hashbucket *head2;
 296         struct inet_bind2_bucket *tb2;
 297         bool conflict = false;
 298         bool reuseport_cb_ok;
 299
 300         rcu_read_lock();
 301         reuseport_cb = rcu_dereference(sk->sk_reuseport_cb);
 302         /* paired with WRITE_ONCE() in __reuseport_(add|detach)_closed_sock */
 303         reuseport_cb_ok = !reuseport_cb || READ_ONCE(reuseport_cb->num_closed_socks);
 304         rcu_read_unlock();
 305
 306         head2 = inet_bhash2_addr_any_hashbucket(sk, net, port);
 307
 308         spin_lock(&head2->lock);
 309
 310         inet_bind_bucket_for_each(tb2, &head2->chain) {
 311                 if (!inet_bind2_bucket_match_addr_any(tb2, net, port, l3mdev, sk))
 312                         continue;
 313
 314                 if (!inet_bhash2_conflict(sk, tb2, uid, relax, reuseport_cb_ok, reuseport_ok))
 315                         continue;
 316
 317                 conflict = true;
 318                 break;
 319         }
 320
 321         spin_unlock(&head2->lock);
 322
 323         return conflict;
 324 }
 325
 326 /*
 327  * Find an open port number for the socket.  Returns with the
 328  * inet_bind_hashbucket locks held if successful.
 329  */
 330 static struct inet_bind_hashbucket *
 331 inet_csk_find_open_port(const struct sock *sk, struct inet_bind_bucket **tb_ret,
 332                         struct inet_bind2_bucket **tb2_ret,
 333                         struct inet_bind_hashbucket **head2_ret, int *port_ret)
 334 {
 335         struct inet_hashinfo *hinfo = tcp_or_dccp_get_hashinfo(sk);
 336         int i, low, high, attempt_half, port, l3mdev;
 337         struct inet_bind_hashbucket *head, *head2;
 338         struct net *net = sock_net(sk);
 339         struct inet_bind2_bucket *tb2;
 340         struct inet_bind_bucket *tb;
 341         u32 remaining, offset;
 342         bool relax = false;
 343
 344         l3mdev = inet_sk_bound_l3mdev(sk);
 345 ports_exhausted:
 346         attempt_half = (sk->sk_reuse == SK_CAN_REUSE) ? 1 : 0;
 347 other_half_scan:
 348         inet_sk_get_local_port_range(sk, &low, &high);
 349         high++; /* [32768, 60999] -> [32768, 61000[ */
 350         if (high - low < 4)
 351                 attempt_half = 0;
 352         if (attempt_half) {
 353                 int half = low + (((high - low) >> 2) << 1);
 354
 355                 if (attempt_half == 1)
 356                         high = half;
 357                 else
 358                         low = half;
 359         }
 360         remaining = high - low;
 361         if (likely(remaining > 1))
 362                 remaining &= ~1U;
 363
 364         offset = get_random_u32_below(remaining);
 365         /* __inet_hash_connect() favors ports having @low parity
 366          * We do the opposite to not pollute connect() users.
 367          */
 368         offset |= 1U;
 369
 370 other_parity_scan:
 371         port = low + offset;
 372         for (i = 0; i < remaining; i += 2, port += 2) {
 373                 if (unlikely(port >= high))
 374                         port -= remaining;
 375                 if (inet_is_local_reserved_port(net, port))
 376                         continue;
 377                 head = &hinfo->bhash[inet_bhashfn(net, port,
 378                                                   hinfo->bhash_size)];
 379                 spin_lock_bh(&head->lock);
 380                 if (inet_use_bhash2_on_bind(sk)) {
 381                         if (inet_bhash2_addr_any_conflict(sk, port, l3mdev, relax, false))
 382                                 goto next_port;
 383                 }
 384
 385                 head2 = inet_bhashfn_portaddr(hinfo, sk, net, port);
 386                 spin_lock(&head2->lock);
 387                 tb2 = inet_bind2_bucket_find(head2, net, port, l3mdev, sk);
 388                 inet_bind_bucket_for_each(tb, &head->chain)
 389                         if (inet_bind_bucket_match(tb, net, port, l3mdev)) {
 390                                 if (!inet_csk_bind_conflict(sk, tb, tb2,
 391                                                             relax, false))
 392                                         goto success;
 393                                 spin_unlock(&head2->lock);
 394                                 goto next_port;
 395                         }
 396                 tb = NULL;
 397                 goto success;
 398 next_port:
 399                 spin_unlock_bh(&head->lock);
 400                 cond_resched();
 401         }
 402
 403         offset--;
 404         if (!(offset & 1))
 405                 goto other_parity_scan;
 406
 407         if (attempt_half == 1) {
 408                 /* OK we now try the upper half of the range */
 409                 attempt_half = 2;
 410                 goto other_half_scan;
 411         }
 412
 413         if (READ_ONCE(net->ipv4.sysctl_ip_autobind_reuse) && !relax) {
 414                 /* We still have a chance to connect to different destinations */
 415                 relax = true;
 416                 goto ports_exhausted;
 417         }
 418         return NULL;
 419 success:
 420         *port_ret = port;
 421         *tb_ret = tb;
 422         *tb2_ret = tb2;
 423         *head2_ret = head2;
 424         return head;
 425 }
 426
 427 static inline int sk_reuseport_match(struct inet_bind_bucket *tb,
 428                                      struct sock *sk)
 429 {
 430         kuid_t uid = sock_i_uid(sk);
 431
 432         if (tb->fastreuseport <= 0)
 433                 return 0;
 434         if (!sk->sk_reuseport)
 435                 return 0;
 436         if (rcu_access_pointer(sk->sk_reuseport_cb))
 437                 return 0;
 438         if (!uid_eq(tb->fastuid, uid))
 439                 return 0;
 440         /* We only need to check the rcv_saddr if this tb was once marked
 441          * without fastreuseport and then was reset, as we can only know that
 442          * the fast_*rcv_saddr doesn't have any conflicts with the socks on the
 443          * owners list.
 444          */
 445         if (tb->fastreuseport == FASTREUSEPORT_ANY)
 446                 return 1;
 447 #if IS_ENABLED(CONFIG_IPV6)
 448         if (tb->fast_sk_family == AF_INET6)
 449                 return ipv6_rcv_saddr_equal(&tb->fast_v6_rcv_saddr,
 450                                             inet6_rcv_saddr(sk),
 451                                             tb->fast_rcv_saddr,
 452                                             sk->sk_rcv_saddr,
 453                                             tb->fast_ipv6_only,
 454                                             ipv6_only_sock(sk), true, false);
 455 #endif
 456         return ipv4_rcv_saddr_equal(tb->fast_rcv_saddr, sk->sk_rcv_saddr,
 457                                     ipv6_only_sock(sk), true, false);
 458 }
 459
 460 void inet_csk_update_fastreuse(struct inet_bind_bucket *tb,
 461                                struct sock *sk)
 462 {
 463         kuid_t uid = sock_i_uid(sk);
 464         bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN;
 465
 466         if (hlist_empty(&tb->bhash2)) {
 467                 tb->fastreuse = reuse;
 468                 if (sk->sk_reuseport) {
 469                         tb->fastreuseport = FASTREUSEPORT_ANY;
 470                         tb->fastuid = uid;
 471                         tb->fast_rcv_saddr = sk->sk_rcv_saddr;
 472                         tb->fast_ipv6_only = ipv6_only_sock(sk);
 473                         tb->fast_sk_family = sk->sk_family;
 474 #if IS_ENABLED(CONFIG_IPV6)
 475                         tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
 476 #endif
 477                 } else {
 478                         tb->fastreuseport = 0;
 479                 }
 480         } else {
 481                 if (!reuse)
 482                         tb->fastreuse = 0;
 483                 if (sk->sk_reuseport) {
 484                         /* We didn't match or we don't have fastreuseport set on
 485                          * the tb, but we have sk_reuseport set on this socket
 486                          * and we know that there are no bind conflicts with
 487                          * this socket in this tb, so reset our tb's reuseport
 488                          * settings so that any subsequent sockets that match
 489                          * our current socket will be put on the fast path.
 490                          *
 491                          * If we reset we need to set FASTREUSEPORT_STRICT so we
 492                          * do extra checking for all subsequent sk_reuseport
 493                          * socks.
 494                          */
 495                         if (!sk_reuseport_match(tb, sk)) {
 496                                 tb->fastreuseport = FASTREUSEPORT_STRICT;
 497                                 tb->fastuid = uid;
 498                                 tb->fast_rcv_saddr = sk->sk_rcv_saddr;
 499                                 tb->fast_ipv6_only = ipv6_only_sock(sk);
 500                                 tb->fast_sk_family = sk->sk_family;
 501 #if IS_ENABLED(CONFIG_IPV6)
 502                                 tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
 503 #endif
 504                         }
 505                 } else {
 506                         tb->fastreuseport = 0;
 507                 }
 508         }
 509 }
 510
 511 /* Obtain a reference to a local port for the given sock,
 512  * if snum is zero it means select any available local port.
 513  * We try to allocate an odd port (and leave even ports for connect())
 514  */
 515 int inet_csk_get_port(struct sock *sk, unsigned short snum)
 516 {
 517         struct inet_hashinfo *hinfo = tcp_or_dccp_get_hashinfo(sk);
 518         bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN;
 519         bool found_port = false, check_bind_conflict = true;
 520         bool bhash_created = false, bhash2_created = false;
 521         int ret = -EADDRINUSE, port = snum, l3mdev;
 522         struct inet_bind_hashbucket *head, *head2;
 523         struct inet_bind2_bucket *tb2 = NULL;
 524         struct inet_bind_bucket *tb = NULL;
 525         bool head2_lock_acquired = false;
 526         struct net *net = sock_net(sk);
 527
 528         l3mdev = inet_sk_bound_l3mdev(sk);
 529
 530         if (!port) {
 531                 head = inet_csk_find_open_port(sk, &tb, &tb2, &head2, &port);
 532                 if (!head)
 533                         return ret;
 534
 535                 head2_lock_acquired = true;
 536
 537                 if (tb && tb2)
 538                         goto success;
 539                 found_port = true;
 540         } else {
 541                 head = &hinfo->bhash[inet_bhashfn(net, port,
 542                                                   hinfo->bhash_size)];
 543                 spin_lock_bh(&head->lock);
 544                 inet_bind_bucket_for_each(tb, &head->chain)
 545                         if (inet_bind_bucket_match(tb, net, port, l3mdev))
 546                                 break;
 547         }
 548
 549         if (!tb) {
 550                 tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep, net,
 551                                              head, port, l3mdev);
 552                 if (!tb)
 553                         goto fail_unlock;
 554                 bhash_created = true;
 555         }
 556
 557         if (!found_port) {
 558                 if (!hlist_empty(&tb->bhash2)) {
 559                         if (sk->sk_reuse == SK_FORCE_REUSE ||
 560                             (tb->fastreuse > 0 && reuse) ||
 561                             sk_reuseport_match(tb, sk))
 562                                 check_bind_conflict = false;
 563                 }
 564
 565                 if (check_bind_conflict && inet_use_bhash2_on_bind(sk)) {
 566                         if (inet_bhash2_addr_any_conflict(sk, port, l3mdev, true, true))
 567                                 goto fail_unlock;
 568                 }
 569
 570                 head2 = inet_bhashfn_portaddr(hinfo, sk, net, port);
 571                 spin_lock(&head2->lock);
 572                 head2_lock_acquired = true;
 573                 tb2 = inet_bind2_bucket_find(head2, net, port, l3mdev, sk);
 574         }
 575
 576         if (!tb2) {
 577                 tb2 = inet_bind2_bucket_create(hinfo->bind2_bucket_cachep,
 578                                                net, head2, tb, sk);
 579                 if (!tb2)
 580                         goto fail_unlock;
 581                 bhash2_created = true;
 582         }
 583
 584         if (!found_port && check_bind_conflict) {
 585                 if (inet_csk_bind_conflict(sk, tb, tb2, true, true))
 586                         goto fail_unlock;
 587         }
 588
 589 success:
 590         inet_csk_update_fastreuse(tb, sk);
 591
 592         if (!inet_csk(sk)->icsk_bind_hash)
 593                 inet_bind_hash(sk, tb, tb2, port);
 594         WARN_ON(inet_csk(sk)->icsk_bind_hash != tb);
 595         WARN_ON(inet_csk(sk)->icsk_bind2_hash != tb2);
 596         ret = 0;
 597
 598 fail_unlock:
 599         if (ret) {
 600                 if (bhash2_created)
 601                         inet_bind2_bucket_destroy(hinfo->bind2_bucket_cachep, tb2);
 602                 if (bhash_created)
 603                         inet_bind_bucket_destroy(hinfo->bind_bucket_cachep, tb);
 604         }
 605         if (head2_lock_acquired)
 606                 spin_unlock(&head2->lock);
 607         spin_unlock_bh(&head->lock);
 608         return ret;
 609 }
 610 EXPORT_SYMBOL_GPL(inet_csk_get_port);
 611
 612 /*
 613  * Wait for an incoming connection, avoid race conditions. This must be called
 614  * with the socket locked.
 615  */
 616 static int inet_csk_wait_for_connect(struct sock *sk, long timeo)
 617 {
 618         struct inet_connection_sock *icsk = inet_csk(sk);
 619         DEFINE_WAIT(wait);
 620         int err;
 621
 622         /*
 623          * True wake-one mechanism for incoming connections: only
 624          * one process gets woken up, not the 'whole herd'.
 625          * Since we do not 'race & poll' for established sockets
 626          * anymore, the common case will execute the loop only once.
 627          *
 628          * Subtle issue: "add_wait_queue_exclusive()" will be added
 629          * after any current non-exclusive waiters, and we know that
 630          * it will always _stay_ after any new non-exclusive waiters
 631          * because all non-exclusive waiters are added at the
 632          * beginning of the wait-queue. As such, it's ok to "drop"
 633          * our exclusiveness temporarily when we get woken up without
 634          * having to remove and re-insert us on the wait queue.
 635          */
 636         for (;;) {
 637                 prepare_to_wait_exclusive(sk_sleep(sk), &wait,
 638                                           TASK_INTERRUPTIBLE);
 639                 release_sock(sk);
 640                 if (reqsk_queue_empty(&icsk->icsk_accept_queue))
 641                         timeo = schedule_timeout(timeo);
 642                 sched_annotate_sleep();
 643                 lock_sock(sk);
 644                 err = 0;
 645                 if (!reqsk_queue_empty(&icsk->icsk_accept_queue))
 646                         break;
 647                 err = -EINVAL;
 648                 if (sk->sk_state != TCP_LISTEN)
 649                         break;
 650                 err = sock_intr_errno(timeo);
 651                 if (signal_pending(current))
 652                         break;
 653                 err = -EAGAIN;
 654                 if (!timeo)
 655                         break;
 656         }
 657         finish_wait(sk_sleep(sk), &wait);
 658         return err;
 659 }
 660
 661 /*
 662  * This will accept the next outstanding connection.
 663  */
 664 struct sock *inet_csk_accept(struct sock *sk, struct proto_accept_arg *arg)
 665 {
 666         struct inet_connection_sock *icsk = inet_csk(sk);
 667         struct request_sock_queue *queue = &icsk->icsk_accept_queue;
 668         struct request_sock *req;
 669         struct sock *newsk;
 670         int error;
 671
 672         lock_sock(sk);
 673
 674         /* We need to make sure that this socket is listening,
 675          * and that it has something pending.
 676          */
 677         error = -EINVAL;
 678         if (sk->sk_state != TCP_LISTEN)
 679                 goto out_err;
 680
 681         /* Find already established connection */
 682         if (reqsk_queue_empty(queue)) {
 683                 long timeo = sock_rcvtimeo(sk, arg->flags & O_NONBLOCK);
 684
 685                 /* If this is a non blocking socket don't sleep */
 686                 error = -EAGAIN;
 687                 if (!timeo)
 688                         goto out_err;
 689
 690                 error = inet_csk_wait_for_connect(sk, timeo);
 691                 if (error)
 692                         goto out_err;
 693         }
 694         req = reqsk_queue_remove(queue, sk);
 695         arg->is_empty = reqsk_queue_empty(queue);
 696         newsk = req->sk;
 697
 698         if (sk->sk_protocol == IPPROTO_TCP &&
 699             tcp_rsk(req)->tfo_listener) {
 700                 spin_lock_bh(&queue->fastopenq.lock);
 701                 if (tcp_rsk(req)->tfo_listener) {
 702                         /* We are still waiting for the final ACK from 3WHS
 703                          * so can't free req now. Instead, we set req->sk to
 704                          * NULL to signify that the child socket is taken
 705                          * so reqsk_fastopen_remove() will free the req
 706                          * when 3WHS finishes (or is aborted).
 707                          */
 708                         req->sk = NULL;
 709                         req = NULL;
 710                 }
 711                 spin_unlock_bh(&queue->fastopenq.lock);
 712         }
 713
 714 out:
 715         release_sock(sk);
 716         if (newsk && mem_cgroup_sockets_enabled) {
 717                 gfp_t gfp = GFP_KERNEL | __GFP_NOFAIL;
 718                 int amt = 0;
 719
 720                 /* atomically get the memory usage, set and charge the
 721                  * newsk->sk_memcg.
 722                  */
 723                 lock_sock(newsk);
 724
 725                 mem_cgroup_sk_alloc(newsk);
 726                 if (newsk->sk_memcg) {
 727                         /* The socket has not been accepted yet, no need
 728                          * to look at newsk->sk_wmem_queued.
 729                          */
 730                         amt = sk_mem_pages(newsk->sk_forward_alloc +
 731                                            atomic_read(&newsk->sk_rmem_alloc));
 732                 }
 733
 734                 if (amt)
 735                         mem_cgroup_charge_skmem(newsk->sk_memcg, amt, gfp);
 736                 kmem_cache_charge(newsk, gfp);
 737
 738                 release_sock(newsk);
 739         }
 740         if (req)
 741                 reqsk_put(req);
 742
 743         if (newsk)
 744                 inet_init_csk_locks(newsk);
 745
 746         return newsk;
 747 out_err:
 748         newsk = NULL;
 749         req = NULL;
 750         arg->err = error;
 751         goto out;
 752 }
 753 EXPORT_SYMBOL(inet_csk_accept);
 754
 755 /*
 756  * Using different timers for retransmit, delayed acks and probes
 757  * We may wish use just one timer maintaining a list of expire jiffies
 758  * to optimize.
 759  */
 760 void inet_csk_init_xmit_timers(struct sock *sk,
 761                                void (*retransmit_handler)(struct timer_list *t),
 762                                void (*delack_handler)(struct timer_list *t),
 763                                void (*keepalive_handler)(struct timer_list *t))
 764 {
 765         struct inet_connection_sock *icsk = inet_csk(sk);
 766
 767         timer_setup(&icsk->icsk_retransmit_timer, retransmit_handler, 0);
 768         timer_setup(&icsk->icsk_delack_timer, delack_handler, 0);
 769         timer_setup(&sk->sk_timer, keepalive_handler, 0);
 770         icsk->icsk_pending = icsk->icsk_ack.pending = 0;
 771 }
 772 EXPORT_SYMBOL(inet_csk_init_xmit_timers);
 773
 774 void inet_csk_clear_xmit_timers(struct sock *sk)
 775 {
 776         struct inet_connection_sock *icsk = inet_csk(sk);
 777
 778         smp_store_release(&icsk->icsk_pending, 0);
 779         smp_store_release(&icsk->icsk_ack.pending, 0);
 780
 781         sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
 782         sk_stop_timer(sk, &icsk->icsk_delack_timer);
 783         sk_stop_timer(sk, &sk->sk_timer);
 784 }
 785 EXPORT_SYMBOL(inet_csk_clear_xmit_timers);
 786
 787 void inet_csk_clear_xmit_timers_sync(struct sock *sk)
 788 {
 789         struct inet_connection_sock *icsk = inet_csk(sk);
 790
 791         /* ongoing timer handlers need to acquire socket lock. */
 792         sock_not_owned_by_me(sk);
 793
 794         smp_store_release(&icsk->icsk_pending, 0);
 795         smp_store_release(&icsk->icsk_ack.pending, 0);
 796
 797         sk_stop_timer_sync(sk, &icsk->icsk_retransmit_timer);
 798         sk_stop_timer_sync(sk, &icsk->icsk_delack_timer);
 799         sk_stop_timer_sync(sk, &sk->sk_timer);
 800 }
 801
 802 void inet_csk_delete_keepalive_timer(struct sock *sk)
 803 {
 804         sk_stop_timer(sk, &sk->sk_timer);
 805 }
 806 EXPORT_SYMBOL(inet_csk_delete_keepalive_timer);
 807
 808 void inet_csk_reset_keepalive_timer(struct sock *sk, unsigned long len)
 809 {
 810         sk_reset_timer(sk, &sk->sk_timer, jiffies + len);
 811 }
 812 EXPORT_SYMBOL(inet_csk_reset_keepalive_timer);
 813
 814 struct dst_entry *inet_csk_route_req(const struct sock *sk,
 815                                      struct flowi4 *fl4,
 816                                      const struct request_sock *req)
 817 {
 818         const struct inet_request_sock *ireq = inet_rsk(req);
 819         struct net *net = read_pnet(&ireq->ireq_net);
 820         struct ip_options_rcu *opt;
 821         struct rtable *rt;
 822
 823         rcu_read_lock();
 824         opt = rcu_dereference(ireq->ireq_opt);
 825
 826         flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
 827                            ip_sock_rt_tos(sk), ip_sock_rt_scope(sk),
 828                            sk->sk_protocol, inet_sk_flowi_flags(sk),
 829                            (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
 830                            ireq->ir_loc_addr, ireq->ir_rmt_port,
 831                            htons(ireq->ir_num), sk->sk_uid);
 832         security_req_classify_flow(req, flowi4_to_flowi_common(fl4));
 833         rt = ip_route_output_flow(net, fl4, sk);
 834         if (IS_ERR(rt))
 835                 goto no_route;
 836         if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
 837                 goto route_err;
 838         rcu_read_unlock();
 839         return &rt->dst;
 840
 841 route_err:
 842         ip_rt_put(rt);
 843 no_route:
 844         rcu_read_unlock();
 845         __IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
 846         return NULL;
 847 }
 848 EXPORT_SYMBOL_GPL(inet_csk_route_req);
 849
 850 struct dst_entry *inet_csk_route_child_sock(const struct sock *sk,
 851                                             struct sock *newsk,
 852                                             const struct request_sock *req)
 853 {
 854         const struct inet_request_sock *ireq = inet_rsk(req);
 855         struct net *net = read_pnet(&ireq->ireq_net);
 856         struct inet_sock *newinet = inet_sk(newsk);
 857         struct ip_options_rcu *opt;
 858         struct flowi4 *fl4;
 859         struct rtable *rt;
 860
 861         opt = rcu_dereference(ireq->ireq_opt);
 862         fl4 = &newinet->cork.fl.u.ip4;
 863
 864         flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
 865                            ip_sock_rt_tos(sk), ip_sock_rt_scope(sk),
 866                            sk->sk_protocol, inet_sk_flowi_flags(sk),
 867                            (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
 868                            ireq->ir_loc_addr, ireq->ir_rmt_port,
 869                            htons(ireq->ir_num), sk->sk_uid);
 870         security_req_classify_flow(req, flowi4_to_flowi_common(fl4));
 871         rt = ip_route_output_flow(net, fl4, sk);
 872         if (IS_ERR(rt))
 873                 goto no_route;
 874         if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
 875                 goto route_err;
 876         return &rt->dst;
 877
 878 route_err:
 879         ip_rt_put(rt);
 880 no_route:
 881         __IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
 882         return NULL;
 883 }
 884 EXPORT_SYMBOL_GPL(inet_csk_route_child_sock);
 885
 886 /* Decide when to expire the request and when to resend SYN-ACK */
 887 static void syn_ack_recalc(struct request_sock *req,
 888                            const int max_syn_ack_retries,
 889                            const u8 rskq_defer_accept,
 890                            int *expire, int *resend)
 891 {
 892         if (!rskq_defer_accept) {
 893                 *expire = req->num_timeout >= max_syn_ack_retries;
 894                 *resend = 1;
 895                 return;
 896         }
 897         *expire = req->num_timeout >= max_syn_ack_retries &&
 898                   (!inet_rsk(req)->acked || req->num_timeout >= rskq_defer_accept);
 899         /* Do not resend while waiting for data after ACK,
 900          * start to resend on end of deferring period to give
 901          * last chance for data or ACK to create established socket.
 902          */
 903         *resend = !inet_rsk(req)->acked ||
 904                   req->num_timeout >= rskq_defer_accept - 1;
 905 }
 906
 907 int inet_rtx_syn_ack(const struct sock *parent, struct request_sock *req)
 908 {
 909         int err = req->rsk_ops->rtx_syn_ack(parent, req);
 910
 911         if (!err)
 912                 req->num_retrans++;
 913         return err;
 914 }
 915 EXPORT_SYMBOL(inet_rtx_syn_ack);
 916
 917 static struct request_sock *
 918 reqsk_alloc_noprof(const struct request_sock_ops *ops, struct sock *sk_listener,
 919                    bool attach_listener)
 920 {
 921         struct request_sock *req;
 922
 923         req = kmem_cache_alloc_noprof(ops->slab, GFP_ATOMIC | __GFP_NOWARN);
 924         if (!req)
 925                 return NULL;
 926         req->rsk_listener = NULL;
 927         if (attach_listener) {
 928                 if (unlikely(!refcount_inc_not_zero(&sk_listener->sk_refcnt))) {
 929                         kmem_cache_free(ops->slab, req);
 930                         return NULL;
 931                 }
 932                 req->rsk_listener = sk_listener;
 933         }
 934         req->rsk_ops = ops;
 935         req_to_sk(req)->sk_prot = sk_listener->sk_prot;
 936         sk_node_init(&req_to_sk(req)->sk_node);
 937         sk_tx_queue_clear(req_to_sk(req));
 938         req->saved_syn = NULL;
 939         req->syncookie = 0;
 940         req->timeout = 0;
 941         req->num_timeout = 0;
 942         req->num_retrans = 0;
 943         req->sk = NULL;
 944         refcount_set(&req->rsk_refcnt, 0);
 945
 946         return req;
 947 }
 948 #define reqsk_alloc(...)        alloc_hooks(reqsk_alloc_noprof(__VA_ARGS__))
 949
 950 struct request_sock *inet_reqsk_alloc(const struct request_sock_ops *ops,
 951                                       struct sock *sk_listener,
 952                                       bool attach_listener)
 953 {
 954         struct request_sock *req = reqsk_alloc(ops, sk_listener,
 955                                                attach_listener);
 956
 957         if (req) {
 958                 struct inet_request_sock *ireq = inet_rsk(req);
 959
 960                 ireq->ireq_opt = NULL;
 961 #if IS_ENABLED(CONFIG_IPV6)
 962                 ireq->pktopts = NULL;
 963 #endif
 964                 atomic64_set(&ireq->ir_cookie, 0);
 965                 ireq->ireq_state = TCP_NEW_SYN_RECV;
 966                 write_pnet(&ireq->ireq_net, sock_net(sk_listener));
 967                 ireq->ireq_family = sk_listener->sk_family;
 968                 req->timeout = TCP_TIMEOUT_INIT;
 969         }
 970
 971         return req;
 972 }
 973 EXPORT_SYMBOL(inet_reqsk_alloc);
 974
 975 static struct request_sock *inet_reqsk_clone(struct request_sock *req,
 976                                              struct sock *sk)
 977 {
 978         struct sock *req_sk, *nreq_sk;
 979         struct request_sock *nreq;
 980
 981         nreq = kmem_cache_alloc(req->rsk_ops->slab, GFP_ATOMIC | __GFP_NOWARN);
 982         if (!nreq) {
 983                 __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQFAILURE);
 984
 985                 /* paired with refcount_inc_not_zero() in reuseport_migrate_sock() */
 986                 sock_put(sk);
 987                 return NULL;
 988         }
 989
 990         req_sk = req_to_sk(req);
 991         nreq_sk = req_to_sk(nreq);
 992
 993         memcpy(nreq_sk, req_sk,
 994                offsetof(struct sock, sk_dontcopy_begin));
 995         unsafe_memcpy(&nreq_sk->sk_dontcopy_end, &req_sk->sk_dontcopy_end,
 996                       req->rsk_ops->obj_size - offsetof(struct sock, sk_dontcopy_end),
 997                       /* alloc is larger than struct, see above */);
 998
 999         sk_node_init(&nreq_sk->sk_node);
1000         nreq_sk->sk_tx_queue_mapping = req_sk->sk_tx_queue_mapping;
1001 #ifdef CONFIG_SOCK_RX_QUEUE_MAPPING
1002         nreq_sk->sk_rx_queue_mapping = req_sk->sk_rx_queue_mapping;
1003 #endif
1004         nreq_sk->sk_incoming_cpu = req_sk->sk_incoming_cpu;
1005
1006         nreq->rsk_listener = sk;
1007
1008         /* We need not acquire fastopenq->lock
1009          * because the child socket is locked in inet_csk_listen_stop().
1010          */
1011         if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(nreq)->tfo_listener)
1012                 rcu_assign_pointer(tcp_sk(nreq->sk)->fastopen_rsk, nreq);
1013
1014         return nreq;
1015 }
1016
1017 static void reqsk_queue_migrated(struct request_sock_queue *queue,
1018                                  const struct request_sock *req)
1019 {
1020         if (req->num_timeout == 0)
1021                 atomic_inc(&queue->young);
1022         atomic_inc(&queue->qlen);
1023 }
1024
1025 static void reqsk_migrate_reset(struct request_sock *req)
1026 {
1027         req->saved_syn = NULL;
1028 #if IS_ENABLED(CONFIG_IPV6)
1029         inet_rsk(req)->ipv6_opt = NULL;
1030         inet_rsk(req)->pktopts = NULL;
1031 #else
1032         inet_rsk(req)->ireq_opt = NULL;
1033 #endif
1034 }
1035
1036 /* return true if req was found in the ehash table */
1037 static bool reqsk_queue_unlink(struct request_sock *req)
1038 {
1039         struct sock *sk = req_to_sk(req);
1040         bool found = false;
1041
1042         if (sk_hashed(sk)) {
1043                 struct inet_hashinfo *hashinfo = tcp_or_dccp_get_hashinfo(sk);
1044                 spinlock_t *lock = inet_ehash_lockp(hashinfo, req->rsk_hash);
1045
1046                 spin_lock(lock);
1047                 found = __sk_nulls_del_node_init_rcu(sk);
1048                 spin_unlock(lock);
1049         }
1050
1051         return found;
1052 }
1053
1054 static bool __inet_csk_reqsk_queue_drop(struct sock *sk,
1055                                         struct request_sock *req,
1056                                         bool from_timer)
1057 {
1058         bool unlinked = reqsk_queue_unlink(req);
1059
1060         if (!from_timer && timer_delete_sync(&req->rsk_timer))
1061                 reqsk_put(req);
1062
1063         if (unlinked) {
1064                 reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req);
1065                 reqsk_put(req);
1066         }
1067
1068         return unlinked;
1069 }
1070
1071 bool inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req)
1072 {
1073         return __inet_csk_reqsk_queue_drop(sk, req, false);
1074 }
1075 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop);
1076
1077 void inet_csk_reqsk_queue_drop_and_put(struct sock *sk, struct request_sock *req)
1078 {
1079         inet_csk_reqsk_queue_drop(sk, req);
1080         reqsk_put(req);
1081 }
1082 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop_and_put);
1083
1084 static void reqsk_timer_handler(struct timer_list *t)
1085 {
1086         struct request_sock *req = from_timer(req, t, rsk_timer);
1087         struct request_sock *nreq = NULL, *oreq = req;
1088         struct sock *sk_listener = req->rsk_listener;
1089         struct inet_connection_sock *icsk;
1090         struct request_sock_queue *queue;
1091         struct net *net;
1092         int max_syn_ack_retries, qlen, expire = 0, resend = 0;
1093
1094         if (inet_sk_state_load(sk_listener) != TCP_LISTEN) {
1095                 struct sock *nsk;
1096
1097                 nsk = reuseport_migrate_sock(sk_listener, req_to_sk(req), NULL);
1098                 if (!nsk)
1099                         goto drop;
1100
1101                 nreq = inet_reqsk_clone(req, nsk);
1102                 if (!nreq)
1103                         goto drop;
1104
1105                 /* The new timer for the cloned req can decrease the 2
1106                  * by calling inet_csk_reqsk_queue_drop_and_put(), so
1107                  * hold another count to prevent use-after-free and
1108                  * call reqsk_put() just before return.
1109                  */
1110                 refcount_set(&nreq->rsk_refcnt, 2 + 1);
1111                 timer_setup(&nreq->rsk_timer, reqsk_timer_handler, TIMER_PINNED);
1112                 reqsk_queue_migrated(&inet_csk(nsk)->icsk_accept_queue, req);
1113
1114                 req = nreq;
1115                 sk_listener = nsk;
1116         }
1117
1118         icsk = inet_csk(sk_listener);
1119         net = sock_net(sk_listener);
1120         max_syn_ack_retries = READ_ONCE(icsk->icsk_syn_retries) ? :
1121                 READ_ONCE(net->ipv4.sysctl_tcp_synack_retries);
1122         /* Normally all the openreqs are young and become mature
1123          * (i.e. converted to established socket) for first timeout.
1124          * If synack was not acknowledged for 1 second, it means
1125          * one of the following things: synack was lost, ack was lost,
1126          * rtt is high or nobody planned to ack (i.e. synflood).
1127          * When server is a bit loaded, queue is populated with old
1128          * open requests, reducing effective size of queue.
1129          * When server is well loaded, queue size reduces to zero
1130          * after several minutes of work. It is not synflood,
1131          * it is normal operation. The solution is pruning
1132          * too old entries overriding normal timeout, when
1133          * situation becomes dangerous.
1134          *
1135          * Essentially, we reserve half of room for young
1136          * embrions; and abort old ones without pity, if old
1137          * ones are about to clog our table.
1138          */
1139         queue = &icsk->icsk_accept_queue;
1140         qlen = reqsk_queue_len(queue);
1141         if ((qlen << 1) > max(8U, READ_ONCE(sk_listener->sk_max_ack_backlog))) {
1142                 int young = reqsk_queue_len_young(queue) << 1;
1143
1144                 while (max_syn_ack_retries > 2) {
1145                         if (qlen < young)
1146                                 break;
1147                         max_syn_ack_retries--;
1148                         young <<= 1;
1149                 }
1150         }
1151         syn_ack_recalc(req, max_syn_ack_retries, READ_ONCE(queue->rskq_defer_accept),
1152                        &expire, &resend);
1153         req->rsk_ops->syn_ack_timeout(req);
1154         if (!expire &&
1155             (!resend ||
1156              !inet_rtx_syn_ack(sk_listener, req) ||
1157              inet_rsk(req)->acked)) {
1158                 if (req->num_timeout++ == 0)
1159                         atomic_dec(&queue->young);
1160                 mod_timer(&req->rsk_timer, jiffies + reqsk_timeout(req, TCP_RTO_MAX));
1161
1162                 if (!nreq)
1163                         return;
1164
1165                 if (!inet_ehash_insert(req_to_sk(nreq), req_to_sk(oreq), NULL)) {
1166                         /* delete timer */
1167                         __inet_csk_reqsk_queue_drop(sk_listener, nreq, true);
1168                         goto no_ownership;
1169                 }
1170
1171                 __NET_INC_STATS(net, LINUX_MIB_TCPMIGRATEREQSUCCESS);
1172                 reqsk_migrate_reset(oreq);
1173                 reqsk_queue_removed(&inet_csk(oreq->rsk_listener)->icsk_accept_queue, oreq);
1174                 reqsk_put(oreq);
1175
1176                 reqsk_put(nreq);
1177                 return;
1178         }
1179
1180         /* Even if we can clone the req, we may need not retransmit any more
1181          * SYN+ACKs (nreq->num_timeout > max_syn_ack_retries, etc), or another
1182          * CPU may win the "own_req" race so that inet_ehash_insert() fails.
1183          */
1184         if (nreq) {
1185                 __NET_INC_STATS(net, LINUX_MIB_TCPMIGRATEREQFAILURE);
1186 no_ownership:
1187                 reqsk_migrate_reset(nreq);
1188                 reqsk_queue_removed(queue, nreq);
1189                 __reqsk_free(nreq);
1190         }
1191
1192 drop:
1193         __inet_csk_reqsk_queue_drop(sk_listener, oreq, true);
1194         reqsk_put(oreq);
1195 }
1196
1197 static bool reqsk_queue_hash_req(struct request_sock *req,
1198                                  unsigned long timeout)
1199 {
1200         bool found_dup_sk = false;
1201
1202         if (!inet_ehash_insert(req_to_sk(req), NULL, &found_dup_sk))
1203                 return false;
1204
1205         /* The timer needs to be setup after a successful insertion. */
1206         timer_setup(&req->rsk_timer, reqsk_timer_handler, TIMER_PINNED);
1207         mod_timer(&req->rsk_timer, jiffies + timeout);
1208
1209         /* before letting lookups find us, make sure all req fields
1210          * are committed to memory and refcnt initialized.
1211          */
1212         smp_wmb();
1213         refcount_set(&req->rsk_refcnt, 2 + 1);
1214         return true;
1215 }
1216
1217 bool inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
1218                                    unsigned long timeout)
1219 {
1220         if (!reqsk_queue_hash_req(req, timeout))
1221                 return false;
1222
1223         inet_csk_reqsk_queue_added(sk);
1224         return true;
1225 }
1226 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add);
1227
1228 static void inet_clone_ulp(const struct request_sock *req, struct sock *newsk,
1229                            const gfp_t priority)
1230 {
1231         struct inet_connection_sock *icsk = inet_csk(newsk);
1232
1233         if (!icsk->icsk_ulp_ops)
1234                 return;
1235
1236         icsk->icsk_ulp_ops->clone(req, newsk, priority);
1237 }
1238
1239 /**
1240  *      inet_csk_clone_lock - clone an inet socket, and lock its clone
1241  *      @sk: the socket to clone
1242  *      @req: request_sock
1243  *      @priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc)
1244  *
1245  *      Caller must unlock socket even in error path (bh_unlock_sock(newsk))
1246  */
1247 struct sock *inet_csk_clone_lock(const struct sock *sk,
1248                                  const struct request_sock *req,
1249                                  const gfp_t priority)
1250 {
1251         struct sock *newsk = sk_clone_lock(sk, priority);
1252
1253         if (newsk) {
1254                 struct inet_connection_sock *newicsk = inet_csk(newsk);
1255
1256                 inet_sk_set_state(newsk, TCP_SYN_RECV);
1257                 newicsk->icsk_bind_hash = NULL;
1258                 newicsk->icsk_bind2_hash = NULL;
1259
1260                 inet_sk(newsk)->inet_dport = inet_rsk(req)->ir_rmt_port;
1261                 inet_sk(newsk)->inet_num = inet_rsk(req)->ir_num;
1262                 inet_sk(newsk)->inet_sport = htons(inet_rsk(req)->ir_num);
1263
1264                 /* listeners have SOCK_RCU_FREE, not the children */
1265                 sock_reset_flag(newsk, SOCK_RCU_FREE);
1266
1267                 inet_sk(newsk)->mc_list = NULL;
1268
1269                 newsk->sk_mark = inet_rsk(req)->ir_mark;
1270                 atomic64_set(&newsk->sk_cookie,
1271                              atomic64_read(&inet_rsk(req)->ir_cookie));
1272
1273                 newicsk->icsk_retransmits = 0;
1274                 newicsk->icsk_backoff     = 0;
1275                 newicsk->icsk_probes_out  = 0;
1276                 newicsk->icsk_probes_tstamp = 0;
1277
1278                 /* Deinitialize accept_queue to trap illegal accesses. */
1279                 memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue));
1280
1281                 inet_clone_ulp(req, newsk, priority);
1282
1283                 security_inet_csk_clone(newsk, req);
1284         }
1285         return newsk;
1286 }
1287 EXPORT_SYMBOL_GPL(inet_csk_clone_lock);
1288
1289 /*
1290  * At this point, there should be no process reference to this
1291  * socket, and thus no user references at all.  Therefore we
1292  * can assume the socket waitqueue is inactive and nobody will
1293  * try to jump onto it.
1294  */
1295 void inet_csk_destroy_sock(struct sock *sk)
1296 {
1297         WARN_ON(sk->sk_state != TCP_CLOSE);
1298         WARN_ON(!sock_flag(sk, SOCK_DEAD));
1299
1300         /* It cannot be in hash table! */
1301         WARN_ON(!sk_unhashed(sk));
1302
1303         /* If it has not 0 inet_sk(sk)->inet_num, it must be bound */
1304         WARN_ON(inet_sk(sk)->inet_num && !inet_csk(sk)->icsk_bind_hash);
1305
1306         sk->sk_prot->destroy(sk);
1307
1308         sk_stream_kill_queues(sk);
1309
1310         xfrm_sk_free_policy(sk);
1311
1312         this_cpu_dec(*sk->sk_prot->orphan_count);
1313
1314         sock_put(sk);
1315 }
1316 EXPORT_SYMBOL(inet_csk_destroy_sock);
1317
1318 /* This function allows to force a closure of a socket after the call to
1319  * tcp/dccp_create_openreq_child().
1320  */
1321 void inet_csk_prepare_forced_close(struct sock *sk)
1322         __releases(&sk->sk_lock.slock)
1323 {
1324         /* sk_clone_lock locked the socket and set refcnt to 2 */
1325         bh_unlock_sock(sk);
1326         sock_put(sk);
1327         inet_csk_prepare_for_destroy_sock(sk);
1328         inet_sk(sk)->inet_num = 0;
1329 }
1330 EXPORT_SYMBOL(inet_csk_prepare_forced_close);
1331
1332 static int inet_ulp_can_listen(const struct sock *sk)
1333 {
1334         const struct inet_connection_sock *icsk = inet_csk(sk);
1335
1336         if (icsk->icsk_ulp_ops && !icsk->icsk_ulp_ops->clone)
1337                 return -EINVAL;
1338
1339         return 0;
1340 }
1341
1342 int inet_csk_listen_start(struct sock *sk)
1343 {
1344         struct inet_connection_sock *icsk = inet_csk(sk);
1345         struct inet_sock *inet = inet_sk(sk);
1346         int err;
1347
1348         err = inet_ulp_can_listen(sk);
1349         if (unlikely(err))
1350                 return err;
1351
1352         reqsk_queue_alloc(&icsk->icsk_accept_queue);
1353
1354         sk->sk_ack_backlog = 0;
1355         inet_csk_delack_init(sk);
1356
1357         /* There is race window here: we announce ourselves listening,
1358          * but this transition is still not validated by get_port().
1359          * It is OK, because this socket enters to hash table only
1360          * after validation is complete.
1361          */
1362         inet_sk_state_store(sk, TCP_LISTEN);
1363         err = sk->sk_prot->get_port(sk, inet->inet_num);
1364         if (!err) {
1365                 inet->inet_sport = htons(inet->inet_num);
1366
1367                 sk_dst_reset(sk);
1368                 err = sk->sk_prot->hash(sk);
1369
1370                 if (likely(!err))
1371                         return 0;
1372         }
1373
1374         inet_sk_set_state(sk, TCP_CLOSE);
1375         return err;
1376 }
1377 EXPORT_SYMBOL_GPL(inet_csk_listen_start);
1378
1379 static void inet_child_forget(struct sock *sk, struct request_sock *req,
1380                               struct sock *child)
1381 {
1382         sk->sk_prot->disconnect(child, O_NONBLOCK);
1383
1384         sock_orphan(child);
1385
1386         this_cpu_inc(*sk->sk_prot->orphan_count);
1387
1388         if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(req)->tfo_listener) {
1389                 BUG_ON(rcu_access_pointer(tcp_sk(child)->fastopen_rsk) != req);
1390                 BUG_ON(sk != req->rsk_listener);
1391
1392                 /* Paranoid, to prevent race condition if
1393                  * an inbound pkt destined for child is
1394                  * blocked by sock lock in tcp_v4_rcv().
1395                  * Also to satisfy an assertion in
1396                  * tcp_v4_destroy_sock().
1397                  */
1398                 RCU_INIT_POINTER(tcp_sk(child)->fastopen_rsk, NULL);
1399         }
1400         inet_csk_destroy_sock(child);
1401 }
1402
1403 struct sock *inet_csk_reqsk_queue_add(struct sock *sk,
1404                                       struct request_sock *req,
1405                                       struct sock *child)
1406 {
1407         struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
1408
1409         spin_lock(&queue->rskq_lock);
1410         if (unlikely(sk->sk_state != TCP_LISTEN)) {
1411                 inet_child_forget(sk, req, child);
1412                 child = NULL;
1413         } else {
1414                 req->sk = child;
1415                 req->dl_next = NULL;
1416                 if (queue->rskq_accept_head == NULL)
1417                         WRITE_ONCE(queue->rskq_accept_head, req);
1418                 else
1419                         queue->rskq_accept_tail->dl_next = req;
1420                 queue->rskq_accept_tail = req;
1421                 sk_acceptq_added(sk);
1422         }
1423         spin_unlock(&queue->rskq_lock);
1424         return child;
1425 }
1426 EXPORT_SYMBOL(inet_csk_reqsk_queue_add);
1427
1428 struct sock *inet_csk_complete_hashdance(struct sock *sk, struct sock *child,
1429                                          struct request_sock *req, bool own_req)
1430 {
1431         if (own_req) {
1432                 inet_csk_reqsk_queue_drop(req->rsk_listener, req);
1433                 reqsk_queue_removed(&inet_csk(req->rsk_listener)->icsk_accept_queue, req);
1434
1435                 if (sk != req->rsk_listener) {
1436                         /* another listening sk has been selected,
1437                          * migrate the req to it.
1438                          */
1439                         struct request_sock *nreq;
1440
1441                         /* hold a refcnt for the nreq->rsk_listener
1442                          * which is assigned in inet_reqsk_clone()
1443                          */
1444                         sock_hold(sk);
1445                         nreq = inet_reqsk_clone(req, sk);
1446                         if (!nreq) {
1447                                 inet_child_forget(sk, req, child);
1448                                 goto child_put;
1449                         }
1450
1451                         refcount_set(&nreq->rsk_refcnt, 1);
1452                         if (inet_csk_reqsk_queue_add(sk, nreq, child)) {
1453                                 __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQSUCCESS);
1454                                 reqsk_migrate_reset(req);
1455                                 reqsk_put(req);
1456                                 return child;
1457                         }
1458
1459                         __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQFAILURE);
1460                         reqsk_migrate_reset(nreq);
1461                         __reqsk_free(nreq);
1462                 } else if (inet_csk_reqsk_queue_add(sk, req, child)) {
1463                         return child;
1464                 }
1465         }
1466         /* Too bad, another child took ownership of the request, undo. */
1467 child_put:
1468         bh_unlock_sock(child);
1469         sock_put(child);
1470         return NULL;
1471 }
1472 EXPORT_SYMBOL(inet_csk_complete_hashdance);
1473
1474 /*
1475  *      This routine closes sockets which have been at least partially
1476  *      opened, but not yet accepted.
1477  */
1478 void inet_csk_listen_stop(struct sock *sk)
1479 {
1480         struct inet_connection_sock *icsk = inet_csk(sk);
1481         struct request_sock_queue *queue = &icsk->icsk_accept_queue;
1482         struct request_sock *next, *req;
1483
1484         /* Following specs, it would be better either to send FIN
1485          * (and enter FIN-WAIT-1, it is normal close)
1486          * or to send active reset (abort).
1487          * Certainly, it is pretty dangerous while synflood, but it is
1488          * bad justification for our negligence 8)
1489          * To be honest, we are not able to make either
1490          * of the variants now.                 --ANK
1491          */
1492         while ((req = reqsk_queue_remove(queue, sk)) != NULL) {
1493                 struct sock *child = req->sk, *nsk;
1494                 struct request_sock *nreq;
1495
1496                 local_bh_disable();
1497                 bh_lock_sock(child);
1498                 WARN_ON(sock_owned_by_user(child));
1499                 sock_hold(child);
1500
1501                 nsk = reuseport_migrate_sock(sk, child, NULL);
1502                 if (nsk) {
1503                         nreq = inet_reqsk_clone(req, nsk);
1504                         if (nreq) {
1505                                 refcount_set(&nreq->rsk_refcnt, 1);
1506
1507                                 if (inet_csk_reqsk_queue_add(nsk, nreq, child)) {
1508                                         __NET_INC_STATS(sock_net(nsk),
1509                                                         LINUX_MIB_TCPMIGRATEREQSUCCESS);
1510                                         reqsk_migrate_reset(req);
1511                                 } else {
1512                                         __NET_INC_STATS(sock_net(nsk),
1513                                                         LINUX_MIB_TCPMIGRATEREQFAILURE);
1514                                         reqsk_migrate_reset(nreq);
1515                                         __reqsk_free(nreq);
1516                                 }
1517
1518                                 /* inet_csk_reqsk_queue_add() has already
1519                                  * called inet_child_forget() on failure case.
1520                                  */
1521                                 goto skip_child_forget;
1522                         }
1523                 }
1524
1525                 inet_child_forget(sk, req, child);
1526 skip_child_forget:
1527                 reqsk_put(req);
1528                 bh_unlock_sock(child);
1529                 local_bh_enable();
1530                 sock_put(child);
1531
1532                 cond_resched();
1533         }
1534         if (queue->fastopenq.rskq_rst_head) {
1535                 /* Free all the reqs queued in rskq_rst_head. */
1536                 spin_lock_bh(&queue->fastopenq.lock);
1537                 req = queue->fastopenq.rskq_rst_head;
1538                 queue->fastopenq.rskq_rst_head = NULL;
1539                 spin_unlock_bh(&queue->fastopenq.lock);
1540                 while (req != NULL) {
1541                         next = req->dl_next;
1542                         reqsk_put(req);
1543                         req = next;
1544                 }
1545         }
1546         WARN_ON_ONCE(sk->sk_ack_backlog);
1547 }
1548 EXPORT_SYMBOL_GPL(inet_csk_listen_stop);
1549
1550 void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr)
1551 {
1552         struct sockaddr_in *sin = (struct sockaddr_in *)uaddr;
1553         const struct inet_sock *inet = inet_sk(sk);
1554
1555         sin->sin_family         = AF_INET;
1556         sin->sin_addr.s_addr    = inet->inet_daddr;
1557         sin->sin_port           = inet->inet_dport;
1558 }
1559 EXPORT_SYMBOL_GPL(inet_csk_addr2sockaddr);
1560
1561 static struct dst_entry *inet_csk_rebuild_route(struct sock *sk, struct flowi *fl)
1562 {
1563         const struct inet_sock *inet = inet_sk(sk);
1564         const struct ip_options_rcu *inet_opt;
1565         __be32 daddr = inet->inet_daddr;
1566         struct flowi4 *fl4;
1567         struct rtable *rt;
1568
1569         rcu_read_lock();
1570         inet_opt = rcu_dereference(inet->inet_opt);
1571         if (inet_opt && inet_opt->opt.srr)
1572                 daddr = inet_opt->opt.faddr;
1573         fl4 = &fl->u.ip4;
1574         rt = ip_route_output_ports(sock_net(sk), fl4, sk, daddr,
1575                                    inet->inet_saddr, inet->inet_dport,
1576                                    inet->inet_sport, sk->sk_protocol,
1577                                    ip_sock_rt_tos(sk), sk->sk_bound_dev_if);
1578         if (IS_ERR(rt))
1579                 rt = NULL;
1580         if (rt)
1581                 sk_setup_caps(sk, &rt->dst);
1582         rcu_read_unlock();
1583
1584         return &rt->dst;
1585 }
1586
1587 struct dst_entry *inet_csk_update_pmtu(struct sock *sk, u32 mtu)
1588 {
1589         struct dst_entry *dst = __sk_dst_check(sk, 0);
1590         struct inet_sock *inet = inet_sk(sk);
1591
1592         if (!dst) {
1593                 dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
1594                 if (!dst)
1595                         goto out;
1596         }
1597         dst->ops->update_pmtu(dst, sk, NULL, mtu, true);
1598
1599         dst = __sk_dst_check(sk, 0);
1600         if (!dst)
1601                 dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
1602 out:
1603         return dst;
1604 }
1605 EXPORT_SYMBOL_GPL(inet_csk_update_pmtu);