net/ipv4/inet_connection_sock.c

   1 /*
   2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3  *              operating system.  INET is implemented using the  BSD Socket
   4  *              interface as the means of communication with the user level.
   5  *
   6  *              Support for INET connection oriented protocols.
   7  *
   8  * Authors:     See the TCP sources
   9  *
  10  *              This program is free software; you can redistribute it and/or
  11  *              modify it under the terms of the GNU General Public License
  12  *              as published by the Free Software Foundation; either version
  13  *              2 of the License, or(at your option) any later version.
  14  */
  15
  16 #include <linux/module.h>
  17 #include <linux/jhash.h>
  18
  19 #include <net/inet_connection_sock.h>
  20 #include <net/inet_hashtables.h>
  21 #include <net/inet_timewait_sock.h>
  22 #include <net/ip.h>
  23 #include <net/route.h>
  24 #include <net/tcp_states.h>
  25 #include <net/xfrm.h>
  26 #include <net/tcp.h>
  27
  28 #ifdef INET_CSK_DEBUG
  29 const char inet_csk_timer_bug_msg[] = "inet_csk BUG: unknown timer value\n";
  30 EXPORT_SYMBOL(inet_csk_timer_bug_msg);
  31 #endif
  32
  33 void inet_get_local_port_range(struct net *net, int *low, int *high)
  34 {
  35         unsigned int seq;
  36
  37         do {
  38                 seq = read_seqbegin(&net->ipv4.ip_local_ports.lock);
  39
  40                 *low = net->ipv4.ip_local_ports.range[0];
  41                 *high = net->ipv4.ip_local_ports.range[1];
  42         } while (read_seqretry(&net->ipv4.ip_local_ports.lock, seq));
  43 }
  44 EXPORT_SYMBOL(inet_get_local_port_range);
  45
  46 int inet_csk_bind_conflict(const struct sock *sk,
  47                            const struct inet_bind_bucket *tb, bool relax)
  48 {
  49         struct sock *sk2;
  50         int reuse = sk->sk_reuse;
  51         int reuseport = sk->sk_reuseport;
  52         kuid_t uid = sock_i_uid((struct sock *)sk);
  53
  54         /*
  55          * Unlike other sk lookup places we do not check
  56          * for sk_net here, since _all_ the socks listed
  57          * in tb->owners list belong to the same net - the
  58          * one this bucket belongs to.
  59          */
  60
  61         sk_for_each_bound(sk2, &tb->owners) {
  62                 if (sk != sk2 &&
  63                     !inet_v6_ipv6only(sk2) &&
  64                     (!sk->sk_bound_dev_if ||
  65                      !sk2->sk_bound_dev_if ||
  66                      sk->sk_bound_dev_if == sk2->sk_bound_dev_if)) {
  67                         if ((!reuse || !sk2->sk_reuse ||
  68                             sk2->sk_state == TCP_LISTEN) &&
  69                             (!reuseport || !sk2->sk_reuseport ||
  70                             (sk2->sk_state != TCP_TIME_WAIT &&
  71                              !uid_eq(uid, sock_i_uid(sk2))))) {
  72
  73                                 if (!sk2->sk_rcv_saddr || !sk->sk_rcv_saddr ||
  74                                     sk2->sk_rcv_saddr == sk->sk_rcv_saddr)
  75                                         break;
  76                         }
  77                         if (!relax && reuse && sk2->sk_reuse &&
  78                             sk2->sk_state != TCP_LISTEN) {
  79
  80                                 if (!sk2->sk_rcv_saddr || !sk->sk_rcv_saddr ||
  81                                     sk2->sk_rcv_saddr == sk->sk_rcv_saddr)
  82                                         break;
  83                         }
  84                 }
  85         }
  86         return sk2 != NULL;
  87 }
  88 EXPORT_SYMBOL_GPL(inet_csk_bind_conflict);
  89
  90 /* Obtain a reference to a local port for the given sock,
  91  * if snum is zero it means select any available local port.
  92  */
  93 int inet_csk_get_port(struct sock *sk, unsigned short snum)
  94 {
  95         struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
  96         struct inet_bind_hashbucket *head;
  97         struct inet_bind_bucket *tb;
  98         int ret, attempts = 5;
  99         struct net *net = sock_net(sk);
 100         int smallest_size = -1, smallest_rover;
 101         kuid_t uid = sock_i_uid(sk);
 102         int attempt_half = (sk->sk_reuse == SK_CAN_REUSE) ? 1 : 0;
 103
 104         local_bh_disable();
 105         if (!snum) {
 106                 int remaining, rover, low, high;
 107
 108 again:
 109                 inet_get_local_port_range(net, &low, &high);
 110                 if (attempt_half) {
 111                         int half = low + ((high - low) >> 1);
 112
 113                         if (attempt_half == 1)
 114                                 high = half;
 115                         else
 116                                 low = half;
 117                 }
 118                 remaining = (high - low) + 1;
 119                 smallest_rover = rover = prandom_u32() % remaining + low;
 120
 121                 smallest_size = -1;
 122                 do {
 123                         if (inet_is_local_reserved_port(net, rover))
 124                                 goto next_nolock;
 125                         head = &hashinfo->bhash[inet_bhashfn(net, rover,
 126                                         hashinfo->bhash_size)];
 127                         spin_lock(&head->lock);
 128                         inet_bind_bucket_for_each(tb, &head->chain)
 129                                 if (net_eq(ib_net(tb), net) && tb->port == rover) {
 130                                         if (((tb->fastreuse > 0 &&
 131                                               sk->sk_reuse &&
 132                                               sk->sk_state != TCP_LISTEN) ||
 133                                              (tb->fastreuseport > 0 &&
 134                                               sk->sk_reuseport &&
 135                                               uid_eq(tb->fastuid, uid))) &&
 136                                             (tb->num_owners < smallest_size || smallest_size == -1)) {
 137                                                 smallest_size = tb->num_owners;
 138                                                 smallest_rover = rover;
 139                                         }
 140                                         if (!inet_csk(sk)->icsk_af_ops->bind_conflict(sk, tb, false)) {
 141                                                 snum = rover;
 142                                                 goto tb_found;
 143                                         }
 144                                         goto next;
 145                                 }
 146                         break;
 147                 next:
 148                         spin_unlock(&head->lock);
 149                 next_nolock:
 150                         if (++rover > high)
 151                                 rover = low;
 152                 } while (--remaining > 0);
 153
 154                 /* Exhausted local port range during search?  It is not
 155                  * possible for us to be holding one of the bind hash
 156                  * locks if this test triggers, because if 'remaining'
 157                  * drops to zero, we broke out of the do/while loop at
 158                  * the top level, not from the 'break;' statement.
 159                  */
 160                 ret = 1;
 161                 if (remaining <= 0) {
 162                         if (smallest_size != -1) {
 163                                 snum = smallest_rover;
 164                                 goto have_snum;
 165                         }
 166                         if (attempt_half == 1) {
 167                                 /* OK we now try the upper half of the range */
 168                                 attempt_half = 2;
 169                                 goto again;
 170                         }
 171                         goto fail;
 172                 }
 173                 /* OK, here is the one we will use.  HEAD is
 174                  * non-NULL and we hold it's mutex.
 175                  */
 176                 snum = rover;
 177         } else {
 178 have_snum:
 179                 head = &hashinfo->bhash[inet_bhashfn(net, snum,
 180                                 hashinfo->bhash_size)];
 181                 spin_lock(&head->lock);
 182                 inet_bind_bucket_for_each(tb, &head->chain)
 183                         if (net_eq(ib_net(tb), net) && tb->port == snum)
 184                                 goto tb_found;
 185         }
 186         tb = NULL;
 187         goto tb_not_found;
 188 tb_found:
 189         if (!hlist_empty(&tb->owners)) {
 190                 if (sk->sk_reuse == SK_FORCE_REUSE)
 191                         goto success;
 192
 193                 if (((tb->fastreuse > 0 &&
 194                       sk->sk_reuse && sk->sk_state != TCP_LISTEN) ||
 195                      (tb->fastreuseport > 0 &&
 196                       sk->sk_reuseport && uid_eq(tb->fastuid, uid))) &&
 197                     smallest_size == -1) {
 198                         goto success;
 199                 } else {
 200                         ret = 1;
 201                         if (inet_csk(sk)->icsk_af_ops->bind_conflict(sk, tb, true)) {
 202                                 if (((sk->sk_reuse && sk->sk_state != TCP_LISTEN) ||
 203                                      (tb->fastreuseport > 0 &&
 204                                       sk->sk_reuseport && uid_eq(tb->fastuid, uid))) &&
 205                                     smallest_size != -1 && --attempts >= 0) {
 206                                         spin_unlock(&head->lock);
 207                                         goto again;
 208                                 }
 209
 210                                 goto fail_unlock;
 211                         }
 212                 }
 213         }
 214 tb_not_found:
 215         ret = 1;
 216         if (!tb && (tb = inet_bind_bucket_create(hashinfo->bind_bucket_cachep,
 217                                         net, head, snum)) == NULL)
 218                 goto fail_unlock;
 219         if (hlist_empty(&tb->owners)) {
 220                 if (sk->sk_reuse && sk->sk_state != TCP_LISTEN)
 221                         tb->fastreuse = 1;
 222                 else
 223                         tb->fastreuse = 0;
 224                 if (sk->sk_reuseport) {
 225                         tb->fastreuseport = 1;
 226                         tb->fastuid = uid;
 227                 } else
 228                         tb->fastreuseport = 0;
 229         } else {
 230                 if (tb->fastreuse &&
 231                     (!sk->sk_reuse || sk->sk_state == TCP_LISTEN))
 232                         tb->fastreuse = 0;
 233                 if (tb->fastreuseport &&
 234                     (!sk->sk_reuseport || !uid_eq(tb->fastuid, uid)))
 235                         tb->fastreuseport = 0;
 236         }
 237 success:
 238         if (!inet_csk(sk)->icsk_bind_hash)
 239                 inet_bind_hash(sk, tb, snum);
 240         WARN_ON(inet_csk(sk)->icsk_bind_hash != tb);
 241         ret = 0;
 242
 243 fail_unlock:
 244         spin_unlock(&head->lock);
 245 fail:
 246         local_bh_enable();
 247         return ret;
 248 }
 249 EXPORT_SYMBOL_GPL(inet_csk_get_port);
 250
 251 /*
 252  * Wait for an incoming connection, avoid race conditions. This must be called
 253  * with the socket locked.
 254  */
 255 static int inet_csk_wait_for_connect(struct sock *sk, long timeo)
 256 {
 257         struct inet_connection_sock *icsk = inet_csk(sk);
 258         DEFINE_WAIT(wait);
 259         int err;
 260
 261         /*
 262          * True wake-one mechanism for incoming connections: only
 263          * one process gets woken up, not the 'whole herd'.
 264          * Since we do not 'race & poll' for established sockets
 265          * anymore, the common case will execute the loop only once.
 266          *
 267          * Subtle issue: "add_wait_queue_exclusive()" will be added
 268          * after any current non-exclusive waiters, and we know that
 269          * it will always _stay_ after any new non-exclusive waiters
 270          * because all non-exclusive waiters are added at the
 271          * beginning of the wait-queue. As such, it's ok to "drop"
 272          * our exclusiveness temporarily when we get woken up without
 273          * having to remove and re-insert us on the wait queue.
 274          */
 275         for (;;) {
 276                 prepare_to_wait_exclusive(sk_sleep(sk), &wait,
 277                                           TASK_INTERRUPTIBLE);
 278                 release_sock(sk);
 279                 if (reqsk_queue_empty(&icsk->icsk_accept_queue))
 280                         timeo = schedule_timeout(timeo);
 281                 sched_annotate_sleep();
 282                 lock_sock(sk);
 283                 err = 0;
 284                 if (!reqsk_queue_empty(&icsk->icsk_accept_queue))
 285                         break;
 286                 err = -EINVAL;
 287                 if (sk->sk_state != TCP_LISTEN)
 288                         break;
 289                 err = sock_intr_errno(timeo);
 290                 if (signal_pending(current))
 291                         break;
 292                 err = -EAGAIN;
 293                 if (!timeo)
 294                         break;
 295         }
 296         finish_wait(sk_sleep(sk), &wait);
 297         return err;
 298 }
 299
 300 /*
 301  * This will accept the next outstanding connection.
 302  */
 303 struct sock *inet_csk_accept(struct sock *sk, int flags, int *err)
 304 {
 305         struct inet_connection_sock *icsk = inet_csk(sk);
 306         struct request_sock_queue *queue = &icsk->icsk_accept_queue;
 307         struct request_sock *req;
 308         struct sock *newsk;
 309         int error;
 310
 311         lock_sock(sk);
 312
 313         /* We need to make sure that this socket is listening,
 314          * and that it has something pending.
 315          */
 316         error = -EINVAL;
 317         if (sk->sk_state != TCP_LISTEN)
 318                 goto out_err;
 319
 320         /* Find already established connection */
 321         if (reqsk_queue_empty(queue)) {
 322                 long timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);
 323
 324                 /* If this is a non blocking socket don't sleep */
 325                 error = -EAGAIN;
 326                 if (!timeo)
 327                         goto out_err;
 328
 329                 error = inet_csk_wait_for_connect(sk, timeo);
 330                 if (error)
 331                         goto out_err;
 332         }
 333         req = reqsk_queue_remove(queue, sk);
 334         newsk = req->sk;
 335
 336         if (sk->sk_protocol == IPPROTO_TCP &&
 337             tcp_rsk(req)->tfo_listener) {
 338                 spin_lock_bh(&queue->fastopenq.lock);
 339                 if (tcp_rsk(req)->tfo_listener) {
 340                         /* We are still waiting for the final ACK from 3WHS
 341                          * so can't free req now. Instead, we set req->sk to
 342                          * NULL to signify that the child socket is taken
 343                          * so reqsk_fastopen_remove() will free the req
 344                          * when 3WHS finishes (or is aborted).
 345                          */
 346                         req->sk = NULL;
 347                         req = NULL;
 348                 }
 349                 spin_unlock_bh(&queue->fastopenq.lock);
 350         }
 351 out:
 352         release_sock(sk);
 353         if (req)
 354                 reqsk_put(req);
 355         return newsk;
 356 out_err:
 357         newsk = NULL;
 358         req = NULL;
 359         *err = error;
 360         goto out;
 361 }
 362 EXPORT_SYMBOL(inet_csk_accept);
 363
 364 /*
 365  * Using different timers for retransmit, delayed acks and probes
 366  * We may wish use just one timer maintaining a list of expire jiffies
 367  * to optimize.
 368  */
 369 void inet_csk_init_xmit_timers(struct sock *sk,
 370                                void (*retransmit_handler)(unsigned long),
 371                                void (*delack_handler)(unsigned long),
 372                                void (*keepalive_handler)(unsigned long))
 373 {
 374         struct inet_connection_sock *icsk = inet_csk(sk);
 375
 376         setup_timer(&icsk->icsk_retransmit_timer, retransmit_handler,
 377                         (unsigned long)sk);
 378         setup_timer(&icsk->icsk_delack_timer, delack_handler,
 379                         (unsigned long)sk);
 380         setup_timer(&sk->sk_timer, keepalive_handler, (unsigned long)sk);
 381         icsk->icsk_pending = icsk->icsk_ack.pending = 0;
 382 }
 383 EXPORT_SYMBOL(inet_csk_init_xmit_timers);
 384
 385 void inet_csk_clear_xmit_timers(struct sock *sk)
 386 {
 387         struct inet_connection_sock *icsk = inet_csk(sk);
 388
 389         icsk->icsk_pending = icsk->icsk_ack.pending = icsk->icsk_ack.blocked = 0;
 390
 391         sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
 392         sk_stop_timer(sk, &icsk->icsk_delack_timer);
 393         sk_stop_timer(sk, &sk->sk_timer);
 394 }
 395 EXPORT_SYMBOL(inet_csk_clear_xmit_timers);
 396
 397 void inet_csk_delete_keepalive_timer(struct sock *sk)
 398 {
 399         sk_stop_timer(sk, &sk->sk_timer);
 400 }
 401 EXPORT_SYMBOL(inet_csk_delete_keepalive_timer);
 402
 403 void inet_csk_reset_keepalive_timer(struct sock *sk, unsigned long len)
 404 {
 405         sk_reset_timer(sk, &sk->sk_timer, jiffies + len);
 406 }
 407 EXPORT_SYMBOL(inet_csk_reset_keepalive_timer);
 408
 409 struct dst_entry *inet_csk_route_req(const struct sock *sk,
 410                                      struct flowi4 *fl4,
 411                                      const struct request_sock *req)
 412 {
 413         const struct inet_request_sock *ireq = inet_rsk(req);
 414         struct net *net = read_pnet(&ireq->ireq_net);
 415         struct ip_options_rcu *opt = ireq->opt;
 416         struct rtable *rt;
 417
 418         flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
 419                            RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
 420                            sk->sk_protocol, inet_sk_flowi_flags(sk),
 421                            (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
 422                            ireq->ir_loc_addr, ireq->ir_rmt_port,
 423                            htons(ireq->ir_num));
 424         security_req_classify_flow(req, flowi4_to_flowi(fl4));
 425         rt = ip_route_output_flow(net, fl4, sk);
 426         if (IS_ERR(rt))
 427                 goto no_route;
 428         if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
 429                 goto route_err;
 430         return &rt->dst;
 431
 432 route_err:
 433         ip_rt_put(rt);
 434 no_route:
 435         IP_INC_STATS_BH(net, IPSTATS_MIB_OUTNOROUTES);
 436         return NULL;
 437 }
 438 EXPORT_SYMBOL_GPL(inet_csk_route_req);
 439
 440 struct dst_entry *inet_csk_route_child_sock(const struct sock *sk,
 441                                             struct sock *newsk,
 442                                             const struct request_sock *req)
 443 {
 444         const struct inet_request_sock *ireq = inet_rsk(req);
 445         struct net *net = read_pnet(&ireq->ireq_net);
 446         struct inet_sock *newinet = inet_sk(newsk);
 447         struct ip_options_rcu *opt;
 448         struct flowi4 *fl4;
 449         struct rtable *rt;
 450
 451         fl4 = &newinet->cork.fl.u.ip4;
 452
 453         rcu_read_lock();
 454         opt = rcu_dereference(newinet->inet_opt);
 455         flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
 456                            RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
 457                            sk->sk_protocol, inet_sk_flowi_flags(sk),
 458                            (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
 459                            ireq->ir_loc_addr, ireq->ir_rmt_port,
 460                            htons(ireq->ir_num));
 461         security_req_classify_flow(req, flowi4_to_flowi(fl4));
 462         rt = ip_route_output_flow(net, fl4, sk);
 463         if (IS_ERR(rt))
 464                 goto no_route;
 465         if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
 466                 goto route_err;
 467         rcu_read_unlock();
 468         return &rt->dst;
 469
 470 route_err:
 471         ip_rt_put(rt);
 472 no_route:
 473         rcu_read_unlock();
 474         IP_INC_STATS_BH(net, IPSTATS_MIB_OUTNOROUTES);
 475         return NULL;
 476 }
 477 EXPORT_SYMBOL_GPL(inet_csk_route_child_sock);
 478
 479 #if IS_ENABLED(CONFIG_IPV6)
 480 #define AF_INET_FAMILY(fam) ((fam) == AF_INET)
 481 #else
 482 #define AF_INET_FAMILY(fam) true
 483 #endif
 484
 485 /* Decide when to expire the request and when to resend SYN-ACK */
 486 static inline void syn_ack_recalc(struct request_sock *req, const int thresh,
 487                                   const int max_retries,
 488                                   const u8 rskq_defer_accept,
 489                                   int *expire, int *resend)
 490 {
 491         if (!rskq_defer_accept) {
 492                 *expire = req->num_timeout >= thresh;
 493                 *resend = 1;
 494                 return;
 495         }
 496         *expire = req->num_timeout >= thresh &&
 497                   (!inet_rsk(req)->acked || req->num_timeout >= max_retries);
 498         /*
 499          * Do not resend while waiting for data after ACK,
 500          * start to resend on end of deferring period to give
 501          * last chance for data or ACK to create established socket.
 502          */
 503         *resend = !inet_rsk(req)->acked ||
 504                   req->num_timeout >= rskq_defer_accept - 1;
 505 }
 506
 507 int inet_rtx_syn_ack(const struct sock *parent, struct request_sock *req)
 508 {
 509         int err = req->rsk_ops->rtx_syn_ack(parent, req);
 510
 511         if (!err)
 512                 req->num_retrans++;
 513         return err;
 514 }
 515 EXPORT_SYMBOL(inet_rtx_syn_ack);
 516
 517 /* return true if req was found in the ehash table */
 518 static bool reqsk_queue_unlink(struct request_sock_queue *queue,
 519                                struct request_sock *req)
 520 {
 521         struct inet_hashinfo *hashinfo = req_to_sk(req)->sk_prot->h.hashinfo;
 522         bool found = false;
 523
 524         if (sk_hashed(req_to_sk(req))) {
 525                 spinlock_t *lock = inet_ehash_lockp(hashinfo, req->rsk_hash);
 526
 527                 spin_lock(lock);
 528                 found = __sk_nulls_del_node_init_rcu(req_to_sk(req));
 529                 spin_unlock(lock);
 530         }
 531         if (timer_pending(&req->rsk_timer) && del_timer_sync(&req->rsk_timer))
 532                 reqsk_put(req);
 533         return found;
 534 }
 535
 536 void inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req)
 537 {
 538         if (reqsk_queue_unlink(&inet_csk(sk)->icsk_accept_queue, req)) {
 539                 reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req);
 540                 reqsk_put(req);
 541         }
 542 }
 543 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop);
 544
 545 void inet_csk_reqsk_queue_drop_and_put(struct sock *sk, struct request_sock *req)
 546 {
 547         inet_csk_reqsk_queue_drop(sk, req);
 548         reqsk_put(req);
 549 }
 550 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop_and_put);
 551
 552 static void reqsk_timer_handler(unsigned long data)
 553 {
 554         struct request_sock *req = (struct request_sock *)data;
 555         struct sock *sk_listener = req->rsk_listener;
 556         struct net *net = sock_net(sk_listener);
 557         struct inet_connection_sock *icsk = inet_csk(sk_listener);
 558         struct request_sock_queue *queue = &icsk->icsk_accept_queue;
 559         int qlen, expire = 0, resend = 0;
 560         int max_retries, thresh;
 561         u8 defer_accept;
 562
 563         if (sk_state_load(sk_listener) != TCP_LISTEN)
 564                 goto drop;
 565
 566         max_retries = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_synack_retries;
 567         thresh = max_retries;
 568         /* Normally all the openreqs are young and become mature
 569          * (i.e. converted to established socket) for first timeout.
 570          * If synack was not acknowledged for 1 second, it means
 571          * one of the following things: synack was lost, ack was lost,
 572          * rtt is high or nobody planned to ack (i.e. synflood).
 573          * When server is a bit loaded, queue is populated with old
 574          * open requests, reducing effective size of queue.
 575          * When server is well loaded, queue size reduces to zero
 576          * after several minutes of work. It is not synflood,
 577          * it is normal operation. The solution is pruning
 578          * too old entries overriding normal timeout, when
 579          * situation becomes dangerous.
 580          *
 581          * Essentially, we reserve half of room for young
 582          * embrions; and abort old ones without pity, if old
 583          * ones are about to clog our table.
 584          */
 585         qlen = reqsk_queue_len(queue);
 586         if ((qlen << 1) > max(8U, sk_listener->sk_max_ack_backlog)) {
 587                 int young = reqsk_queue_len_young(queue) << 1;
 588
 589                 while (thresh > 2) {
 590                         if (qlen < young)
 591                                 break;
 592                         thresh--;
 593                         young <<= 1;
 594                 }
 595         }
 596         defer_accept = READ_ONCE(queue->rskq_defer_accept);
 597         if (defer_accept)
 598                 max_retries = defer_accept;
 599         syn_ack_recalc(req, thresh, max_retries, defer_accept,
 600                        &expire, &resend);
 601         req->rsk_ops->syn_ack_timeout(req);
 602         if (!expire &&
 603             (!resend ||
 604              !inet_rtx_syn_ack(sk_listener, req) ||
 605              inet_rsk(req)->acked)) {
 606                 unsigned long timeo;
 607
 608                 if (req->num_timeout++ == 0)
 609                         atomic_dec(&queue->young);
 610                 timeo = min(TCP_TIMEOUT_INIT << req->num_timeout, TCP_RTO_MAX);
 611                 mod_timer_pinned(&req->rsk_timer, jiffies + timeo);
 612                 return;
 613         }
 614 drop:
 615         inet_csk_reqsk_queue_drop_and_put(sk_listener, req);
 616 }
 617
 618 static void reqsk_queue_hash_req(struct request_sock *req,
 619                                  unsigned long timeout)
 620 {
 621         req->num_retrans = 0;
 622         req->num_timeout = 0;
 623         req->sk = NULL;
 624
 625         setup_timer(&req->rsk_timer, reqsk_timer_handler, (unsigned long)req);
 626         mod_timer_pinned(&req->rsk_timer, jiffies + timeout);
 627
 628         inet_ehash_insert(req_to_sk(req), NULL);
 629         /* before letting lookups find us, make sure all req fields
 630          * are committed to memory and refcnt initialized.
 631          */
 632         smp_wmb();
 633         atomic_set(&req->rsk_refcnt, 2 + 1);
 634 }
 635
 636 void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
 637                                    unsigned long timeout)
 638 {
 639         reqsk_queue_hash_req(req, timeout);
 640         inet_csk_reqsk_queue_added(sk);
 641 }
 642 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add);
 643
 644 /**
 645  *      inet_csk_clone_lock - clone an inet socket, and lock its clone
 646  *      @sk: the socket to clone
 647  *      @req: request_sock
 648  *      @priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc)
 649  *
 650  *      Caller must unlock socket even in error path (bh_unlock_sock(newsk))
 651  */
 652 struct sock *inet_csk_clone_lock(const struct sock *sk,
 653                                  const struct request_sock *req,
 654                                  const gfp_t priority)
 655 {
 656         struct sock *newsk = sk_clone_lock(sk, priority);
 657
 658         if (newsk) {
 659                 struct inet_connection_sock *newicsk = inet_csk(newsk);
 660
 661                 newsk->sk_state = TCP_SYN_RECV;
 662                 newicsk->icsk_bind_hash = NULL;
 663
 664                 inet_sk(newsk)->inet_dport = inet_rsk(req)->ir_rmt_port;
 665                 inet_sk(newsk)->inet_num = inet_rsk(req)->ir_num;
 666                 inet_sk(newsk)->inet_sport = htons(inet_rsk(req)->ir_num);
 667                 newsk->sk_write_space = sk_stream_write_space;
 668
 669                 newsk->sk_mark = inet_rsk(req)->ir_mark;
 670                 atomic64_set(&newsk->sk_cookie,
 671                              atomic64_read(&inet_rsk(req)->ir_cookie));
 672
 673                 newicsk->icsk_retransmits = 0;
 674                 newicsk->icsk_backoff     = 0;
 675                 newicsk->icsk_probes_out  = 0;
 676
 677                 /* Deinitialize accept_queue to trap illegal accesses. */
 678                 memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue));
 679
 680                 security_inet_csk_clone(newsk, req);
 681         }
 682         return newsk;
 683 }
 684 EXPORT_SYMBOL_GPL(inet_csk_clone_lock);
 685
 686 /*
 687  * At this point, there should be no process reference to this
 688  * socket, and thus no user references at all.  Therefore we
 689  * can assume the socket waitqueue is inactive and nobody will
 690  * try to jump onto it.
 691  */
 692 void inet_csk_destroy_sock(struct sock *sk)
 693 {
 694         WARN_ON(sk->sk_state != TCP_CLOSE);
 695         WARN_ON(!sock_flag(sk, SOCK_DEAD));
 696
 697         /* It cannot be in hash table! */
 698         WARN_ON(!sk_unhashed(sk));
 699
 700         /* If it has not 0 inet_sk(sk)->inet_num, it must be bound */
 701         WARN_ON(inet_sk(sk)->inet_num && !inet_csk(sk)->icsk_bind_hash);
 702
 703         sk->sk_prot->destroy(sk);
 704
 705         sk_stream_kill_queues(sk);
 706
 707         xfrm_sk_free_policy(sk);
 708
 709         sk_refcnt_debug_release(sk);
 710
 711         percpu_counter_dec(sk->sk_prot->orphan_count);
 712         sock_put(sk);
 713 }
 714 EXPORT_SYMBOL(inet_csk_destroy_sock);
 715
 716 /* This function allows to force a closure of a socket after the call to
 717  * tcp/dccp_create_openreq_child().
 718  */
 719 void inet_csk_prepare_forced_close(struct sock *sk)
 720         __releases(&sk->sk_lock.slock)
 721 {
 722         /* sk_clone_lock locked the socket and set refcnt to 2 */
 723         bh_unlock_sock(sk);
 724         sock_put(sk);
 725
 726         /* The below has to be done to allow calling inet_csk_destroy_sock */
 727         sock_set_flag(sk, SOCK_DEAD);
 728         percpu_counter_inc(sk->sk_prot->orphan_count);
 729         inet_sk(sk)->inet_num = 0;
 730 }
 731 EXPORT_SYMBOL(inet_csk_prepare_forced_close);
 732
 733 int inet_csk_listen_start(struct sock *sk, int backlog)
 734 {
 735         struct inet_connection_sock *icsk = inet_csk(sk);
 736         struct inet_sock *inet = inet_sk(sk);
 737         int err = -EADDRINUSE;
 738
 739         reqsk_queue_alloc(&icsk->icsk_accept_queue);
 740
 741         sk->sk_max_ack_backlog = backlog;
 742         sk->sk_ack_backlog = 0;
 743         inet_csk_delack_init(sk);
 744
 745         /* There is race window here: we announce ourselves listening,
 746          * but this transition is still not validated by get_port().
 747          * It is OK, because this socket enters to hash table only
 748          * after validation is complete.
 749          */
 750         sk_state_store(sk, TCP_LISTEN);
 751         if (!sk->sk_prot->get_port(sk, inet->inet_num)) {
 752                 inet->inet_sport = htons(inet->inet_num);
 753
 754                 sk_dst_reset(sk);
 755                 err = sk->sk_prot->hash(sk);
 756
 757                 if (likely(!err))
 758                         return 0;
 759         }
 760
 761         sk->sk_state = TCP_CLOSE;
 762         return err;
 763 }
 764 EXPORT_SYMBOL_GPL(inet_csk_listen_start);
 765
 766 static void inet_child_forget(struct sock *sk, struct request_sock *req,
 767                               struct sock *child)
 768 {
 769         sk->sk_prot->disconnect(child, O_NONBLOCK);
 770
 771         sock_orphan(child);
 772
 773         percpu_counter_inc(sk->sk_prot->orphan_count);
 774
 775         if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(req)->tfo_listener) {
 776                 BUG_ON(tcp_sk(child)->fastopen_rsk != req);
 777                 BUG_ON(sk != req->rsk_listener);
 778
 779                 /* Paranoid, to prevent race condition if
 780                  * an inbound pkt destined for child is
 781                  * blocked by sock lock in tcp_v4_rcv().
 782                  * Also to satisfy an assertion in
 783                  * tcp_v4_destroy_sock().
 784                  */
 785                 tcp_sk(child)->fastopen_rsk = NULL;
 786         }
 787         inet_csk_destroy_sock(child);
 788         reqsk_put(req);
 789 }
 790
 791 void inet_csk_reqsk_queue_add(struct sock *sk, struct request_sock *req,
 792                               struct sock *child)
 793 {
 794         struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
 795
 796         spin_lock(&queue->rskq_lock);
 797         if (unlikely(sk->sk_state != TCP_LISTEN)) {
 798                 inet_child_forget(sk, req, child);
 799         } else {
 800                 req->sk = child;
 801                 req->dl_next = NULL;
 802                 if (queue->rskq_accept_head == NULL)
 803                         queue->rskq_accept_head = req;
 804                 else
 805                         queue->rskq_accept_tail->dl_next = req;
 806                 queue->rskq_accept_tail = req;
 807                 sk_acceptq_added(sk);
 808         }
 809         spin_unlock(&queue->rskq_lock);
 810 }
 811 EXPORT_SYMBOL(inet_csk_reqsk_queue_add);
 812
 813 struct sock *inet_csk_complete_hashdance(struct sock *sk, struct sock *child,
 814                                          struct request_sock *req, bool own_req)
 815 {
 816         if (own_req) {
 817                 inet_csk_reqsk_queue_drop(sk, req);
 818                 reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req);
 819                 inet_csk_reqsk_queue_add(sk, req, child);
 820                 /* Warning: caller must not call reqsk_put(req);
 821                  * child stole last reference on it.
 822                  */
 823                 return child;
 824         }
 825         /* Too bad, another child took ownership of the request, undo. */
 826         bh_unlock_sock(child);
 827         sock_put(child);
 828         return NULL;
 829 }
 830 EXPORT_SYMBOL(inet_csk_complete_hashdance);
 831
 832 /*
 833  *      This routine closes sockets which have been at least partially
 834  *      opened, but not yet accepted.
 835  */
 836 void inet_csk_listen_stop(struct sock *sk)
 837 {
 838         struct inet_connection_sock *icsk = inet_csk(sk);
 839         struct request_sock_queue *queue = &icsk->icsk_accept_queue;
 840         struct request_sock *next, *req;
 841
 842         /* Following specs, it would be better either to send FIN
 843          * (and enter FIN-WAIT-1, it is normal close)
 844          * or to send active reset (abort).
 845          * Certainly, it is pretty dangerous while synflood, but it is
 846          * bad justification for our negligence 8)
 847          * To be honest, we are not able to make either
 848          * of the variants now.                 --ANK
 849          */
 850         while ((req = reqsk_queue_remove(queue, sk)) != NULL) {
 851                 struct sock *child = req->sk;
 852
 853                 local_bh_disable();
 854                 bh_lock_sock(child);
 855                 WARN_ON(sock_owned_by_user(child));
 856                 sock_hold(child);
 857
 858                 inet_child_forget(sk, req, child);
 859                 bh_unlock_sock(child);
 860                 local_bh_enable();
 861                 sock_put(child);
 862
 863                 cond_resched();
 864         }
 865         if (queue->fastopenq.rskq_rst_head) {
 866                 /* Free all the reqs queued in rskq_rst_head. */
 867                 spin_lock_bh(&queue->fastopenq.lock);
 868                 req = queue->fastopenq.rskq_rst_head;
 869                 queue->fastopenq.rskq_rst_head = NULL;
 870                 spin_unlock_bh(&queue->fastopenq.lock);
 871                 while (req != NULL) {
 872                         next = req->dl_next;
 873                         reqsk_put(req);
 874                         req = next;
 875                 }
 876         }
 877         WARN_ON_ONCE(sk->sk_ack_backlog);
 878 }
 879 EXPORT_SYMBOL_GPL(inet_csk_listen_stop);
 880
 881 void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr)
 882 {
 883         struct sockaddr_in *sin = (struct sockaddr_in *)uaddr;
 884         const struct inet_sock *inet = inet_sk(sk);
 885
 886         sin->sin_family         = AF_INET;
 887         sin->sin_addr.s_addr    = inet->inet_daddr;
 888         sin->sin_port           = inet->inet_dport;
 889 }
 890 EXPORT_SYMBOL_GPL(inet_csk_addr2sockaddr);
 891
 892 #ifdef CONFIG_COMPAT
 893 int inet_csk_compat_getsockopt(struct sock *sk, int level, int optname,
 894                                char __user *optval, int __user *optlen)
 895 {
 896         const struct inet_connection_sock *icsk = inet_csk(sk);
 897
 898         if (icsk->icsk_af_ops->compat_getsockopt)
 899                 return icsk->icsk_af_ops->compat_getsockopt(sk, level, optname,
 900                                                             optval, optlen);
 901         return icsk->icsk_af_ops->getsockopt(sk, level, optname,
 902                                              optval, optlen);
 903 }
 904 EXPORT_SYMBOL_GPL(inet_csk_compat_getsockopt);
 905
 906 int inet_csk_compat_setsockopt(struct sock *sk, int level, int optname,
 907                                char __user *optval, unsigned int optlen)
 908 {
 909         const struct inet_connection_sock *icsk = inet_csk(sk);
 910
 911         if (icsk->icsk_af_ops->compat_setsockopt)
 912                 return icsk->icsk_af_ops->compat_setsockopt(sk, level, optname,
 913                                                             optval, optlen);
 914         return icsk->icsk_af_ops->setsockopt(sk, level, optname,
 915                                              optval, optlen);
 916 }
 917 EXPORT_SYMBOL_GPL(inet_csk_compat_setsockopt);
 918 #endif
 919
 920 static struct dst_entry *inet_csk_rebuild_route(struct sock *sk, struct flowi *fl)
 921 {
 922         const struct inet_sock *inet = inet_sk(sk);
 923         const struct ip_options_rcu *inet_opt;
 924         __be32 daddr = inet->inet_daddr;
 925         struct flowi4 *fl4;
 926         struct rtable *rt;
 927
 928         rcu_read_lock();
 929         inet_opt = rcu_dereference(inet->inet_opt);
 930         if (inet_opt && inet_opt->opt.srr)
 931                 daddr = inet_opt->opt.faddr;
 932         fl4 = &fl->u.ip4;
 933         rt = ip_route_output_ports(sock_net(sk), fl4, sk, daddr,
 934                                    inet->inet_saddr, inet->inet_dport,
 935                                    inet->inet_sport, sk->sk_protocol,
 936                                    RT_CONN_FLAGS(sk), sk->sk_bound_dev_if);
 937         if (IS_ERR(rt))
 938                 rt = NULL;
 939         if (rt)
 940                 sk_setup_caps(sk, &rt->dst);
 941         rcu_read_unlock();
 942
 943         return &rt->dst;
 944 }
 945
 946 struct dst_entry *inet_csk_update_pmtu(struct sock *sk, u32 mtu)
 947 {
 948         struct dst_entry *dst = __sk_dst_check(sk, 0);
 949         struct inet_sock *inet = inet_sk(sk);
 950
 951         if (!dst) {
 952                 dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
 953                 if (!dst)
 954                         goto out;
 955         }
 956         dst->ops->update_pmtu(dst, sk, NULL, mtu);
 957
 958         dst = __sk_dst_check(sk, 0);
 959         if (!dst)
 960                 dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
 961 out:
 962         return dst;
 963 }
 964 EXPORT_SYMBOL_GPL(inet_csk_update_pmtu);