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 #include <net/sock_reuseport.h>
  28
  29 #ifdef INET_CSK_DEBUG
  30 const char inet_csk_timer_bug_msg[] = "inet_csk BUG: unknown timer value\n";
  31 EXPORT_SYMBOL(inet_csk_timer_bug_msg);
  32 #endif
  33
  34 void inet_get_local_port_range(struct net *net, int *low, int *high)
  35 {
  36         unsigned int seq;
  37
  38         do {
  39                 seq = read_seqbegin(&net->ipv4.ip_local_ports.lock);
  40
  41                 *low = net->ipv4.ip_local_ports.range[0];
  42                 *high = net->ipv4.ip_local_ports.range[1];
  43         } while (read_seqretry(&net->ipv4.ip_local_ports.lock, seq));
  44 }
  45 EXPORT_SYMBOL(inet_get_local_port_range);
  46
  47 int inet_csk_bind_conflict(const struct sock *sk,
  48                            const struct inet_bind_bucket *tb, bool relax)
  49 {
  50         struct sock *sk2;
  51         int reuse = sk->sk_reuse;
  52         int reuseport = sk->sk_reuseport;
  53         kuid_t uid = sock_i_uid((struct sock *)sk);
  54
  55         /*
  56          * Unlike other sk lookup places we do not check
  57          * for sk_net here, since _all_ the socks listed
  58          * in tb->owners list belong to the same net - the
  59          * one this bucket belongs to.
  60          */
  61
  62         sk_for_each_bound(sk2, &tb->owners) {
  63                 if (sk != sk2 &&
  64                     !inet_v6_ipv6only(sk2) &&
  65                     (!sk->sk_bound_dev_if ||
  66                      !sk2->sk_bound_dev_if ||
  67                      sk->sk_bound_dev_if == sk2->sk_bound_dev_if)) {
  68                         if ((!reuse || !sk2->sk_reuse ||
  69                             sk2->sk_state == TCP_LISTEN) &&
  70                             (!reuseport || !sk2->sk_reuseport ||
  71                              rcu_access_pointer(sk->sk_reuseport_cb) ||
  72                              (sk2->sk_state != TCP_TIME_WAIT &&
  73                              !uid_eq(uid, sock_i_uid(sk2))))) {
  74
  75                                 if (!sk2->sk_rcv_saddr || !sk->sk_rcv_saddr ||
  76                                     sk2->sk_rcv_saddr == sk->sk_rcv_saddr)
  77                                         break;
  78                         }
  79                         if (!relax && reuse && sk2->sk_reuse &&
  80                             sk2->sk_state != TCP_LISTEN) {
  81
  82                                 if (!sk2->sk_rcv_saddr || !sk->sk_rcv_saddr ||
  83                                     sk2->sk_rcv_saddr == sk->sk_rcv_saddr)
  84                                         break;
  85                         }
  86                 }
  87         }
  88         return sk2 != NULL;
  89 }
  90 EXPORT_SYMBOL_GPL(inet_csk_bind_conflict);
  91
  92 /* Obtain a reference to a local port for the given sock,
  93  * if snum is zero it means select any available local port.
  94  * We try to allocate an odd port (and leave even ports for connect())
  95  */
  96 int inet_csk_get_port(struct sock *sk, unsigned short snum)
  97 {
  98         bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN;
  99         struct inet_hashinfo *hinfo = sk->sk_prot->h.hashinfo;
 100         int ret = 1, attempts = 5, port = snum;
 101         int smallest_size = -1, smallest_port;
 102         struct inet_bind_hashbucket *head;
 103         struct net *net = sock_net(sk);
 104         int i, low, high, attempt_half;
 105         struct inet_bind_bucket *tb;
 106         kuid_t uid = sock_i_uid(sk);
 107         u32 remaining, offset;
 108
 109         if (port) {
 110 have_port:
 111                 head = &hinfo->bhash[inet_bhashfn(net, port,
 112                                                   hinfo->bhash_size)];
 113                 spin_lock_bh(&head->lock);
 114                 inet_bind_bucket_for_each(tb, &head->chain)
 115                         if (net_eq(ib_net(tb), net) && tb->port == port)
 116                                 goto tb_found;
 117
 118                 goto tb_not_found;
 119         }
 120 again:
 121         attempt_half = (sk->sk_reuse == SK_CAN_REUSE) ? 1 : 0;
 122 other_half_scan:
 123         inet_get_local_port_range(net, &low, &high);
 124         high++; /* [32768, 60999] -> [32768, 61000[ */
 125         if (high - low < 4)
 126                 attempt_half = 0;
 127         if (attempt_half) {
 128                 int half = low + (((high - low) >> 2) << 1);
 129
 130                 if (attempt_half == 1)
 131                         high = half;
 132                 else
 133                         low = half;
 134         }
 135         remaining = high - low;
 136         if (likely(remaining > 1))
 137                 remaining &= ~1U;
 138
 139         offset = prandom_u32() % remaining;
 140         /* __inet_hash_connect() favors ports having @low parity
 141          * We do the opposite to not pollute connect() users.
 142          */
 143         offset |= 1U;
 144         smallest_size = -1;
 145         smallest_port = low; /* avoid compiler warning */
 146
 147 other_parity_scan:
 148         port = low + offset;
 149         for (i = 0; i < remaining; i += 2, port += 2) {
 150                 if (unlikely(port >= high))
 151                         port -= remaining;
 152                 if (inet_is_local_reserved_port(net, port))
 153                         continue;
 154                 head = &hinfo->bhash[inet_bhashfn(net, port,
 155                                                   hinfo->bhash_size)];
 156                 spin_lock_bh(&head->lock);
 157                 inet_bind_bucket_for_each(tb, &head->chain)
 158                         if (net_eq(ib_net(tb), net) && tb->port == port) {
 159                                 if (((tb->fastreuse > 0 && reuse) ||
 160                                      (tb->fastreuseport > 0 &&
 161                                       sk->sk_reuseport &&
 162                                       !rcu_access_pointer(sk->sk_reuseport_cb) &&
 163                                       uid_eq(tb->fastuid, uid))) &&
 164                                     (tb->num_owners < smallest_size || smallest_size == -1)) {
 165                                         smallest_size = tb->num_owners;
 166                                         smallest_port = port;
 167                                 }
 168                                 if (!inet_csk(sk)->icsk_af_ops->bind_conflict(sk, tb, false))
 169                                         goto tb_found;
 170                                 goto next_port;
 171                         }
 172                 goto tb_not_found;
 173 next_port:
 174                 spin_unlock_bh(&head->lock);
 175                 cond_resched();
 176         }
 177
 178         if (smallest_size != -1) {
 179                 port = smallest_port;
 180                 goto have_port;
 181         }
 182         offset--;
 183         if (!(offset & 1))
 184                 goto other_parity_scan;
 185
 186         if (attempt_half == 1) {
 187                 /* OK we now try the upper half of the range */
 188                 attempt_half = 2;
 189                 goto other_half_scan;
 190         }
 191         return ret;
 192
 193 tb_not_found:
 194         tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep,
 195                                      net, head, port);
 196         if (!tb)
 197                 goto fail_unlock;
 198 tb_found:
 199         if (!hlist_empty(&tb->owners)) {
 200                 if (sk->sk_reuse == SK_FORCE_REUSE)
 201                         goto success;
 202
 203                 if (((tb->fastreuse > 0 && reuse) ||
 204                      (tb->fastreuseport > 0 &&
 205                       !rcu_access_pointer(sk->sk_reuseport_cb) &&
 206                       sk->sk_reuseport && uid_eq(tb->fastuid, uid))) &&
 207                     smallest_size == -1)
 208                         goto success;
 209                 if (inet_csk(sk)->icsk_af_ops->bind_conflict(sk, tb, true)) {
 210                         if ((reuse ||
 211                              (tb->fastreuseport > 0 &&
 212                               sk->sk_reuseport &&
 213                               !rcu_access_pointer(sk->sk_reuseport_cb) &&
 214                               uid_eq(tb->fastuid, uid))) &&
 215                             smallest_size != -1 && --attempts >= 0) {
 216                                 spin_unlock_bh(&head->lock);
 217                                 goto again;
 218                         }
 219                         goto fail_unlock;
 220                 }
 221                 if (!reuse)
 222                         tb->fastreuse = 0;
 223                 if (!sk->sk_reuseport || !uid_eq(tb->fastuid, uid))
 224                         tb->fastreuseport = 0;
 225         } else {
 226                 tb->fastreuse = reuse;
 227                 if (sk->sk_reuseport) {
 228                         tb->fastreuseport = 1;
 229                         tb->fastuid = uid;
 230                 } else {
 231                         tb->fastreuseport = 0;
 232                 }
 233         }
 234 success:
 235         if (!inet_csk(sk)->icsk_bind_hash)
 236                 inet_bind_hash(sk, tb, port);
 237         WARN_ON(inet_csk(sk)->icsk_bind_hash != tb);
 238         ret = 0;
 239
 240 fail_unlock:
 241         spin_unlock_bh(&head->lock);
 242         return ret;
 243 }
 244 EXPORT_SYMBOL_GPL(inet_csk_get_port);
 245
 246 /*
 247  * Wait for an incoming connection, avoid race conditions. This must be called
 248  * with the socket locked.
 249  */
 250 static int inet_csk_wait_for_connect(struct sock *sk, long timeo)
 251 {
 252         struct inet_connection_sock *icsk = inet_csk(sk);
 253         DEFINE_WAIT(wait);
 254         int err;
 255
 256         /*
 257          * True wake-one mechanism for incoming connections: only
 258          * one process gets woken up, not the 'whole herd'.
 259          * Since we do not 'race & poll' for established sockets
 260          * anymore, the common case will execute the loop only once.
 261          *
 262          * Subtle issue: "add_wait_queue_exclusive()" will be added
 263          * after any current non-exclusive waiters, and we know that
 264          * it will always _stay_ after any new non-exclusive waiters
 265          * because all non-exclusive waiters are added at the
 266          * beginning of the wait-queue. As such, it's ok to "drop"
 267          * our exclusiveness temporarily when we get woken up without
 268          * having to remove and re-insert us on the wait queue.
 269          */
 270         for (;;) {
 271                 prepare_to_wait_exclusive(sk_sleep(sk), &wait,
 272                                           TASK_INTERRUPTIBLE);
 273                 release_sock(sk);
 274                 if (reqsk_queue_empty(&icsk->icsk_accept_queue))
 275                         timeo = schedule_timeout(timeo);
 276                 sched_annotate_sleep();
 277                 lock_sock(sk);
 278                 err = 0;
 279                 if (!reqsk_queue_empty(&icsk->icsk_accept_queue))
 280                         break;
 281                 err = -EINVAL;
 282                 if (sk->sk_state != TCP_LISTEN)
 283                         break;
 284                 err = sock_intr_errno(timeo);
 285                 if (signal_pending(current))
 286                         break;
 287                 err = -EAGAIN;
 288                 if (!timeo)
 289                         break;
 290         }
 291         finish_wait(sk_sleep(sk), &wait);
 292         return err;
 293 }
 294
 295 /*
 296  * This will accept the next outstanding connection.
 297  */
 298 struct sock *inet_csk_accept(struct sock *sk, int flags, int *err)
 299 {
 300         struct inet_connection_sock *icsk = inet_csk(sk);
 301         struct request_sock_queue *queue = &icsk->icsk_accept_queue;
 302         struct request_sock *req;
 303         struct sock *newsk;
 304         int error;
 305
 306         lock_sock(sk);
 307
 308         /* We need to make sure that this socket is listening,
 309          * and that it has something pending.
 310          */
 311         error = -EINVAL;
 312         if (sk->sk_state != TCP_LISTEN)
 313                 goto out_err;
 314
 315         /* Find already established connection */
 316         if (reqsk_queue_empty(queue)) {
 317                 long timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);
 318
 319                 /* If this is a non blocking socket don't sleep */
 320                 error = -EAGAIN;
 321                 if (!timeo)
 322                         goto out_err;
 323
 324                 error = inet_csk_wait_for_connect(sk, timeo);
 325                 if (error)
 326                         goto out_err;
 327         }
 328         req = reqsk_queue_remove(queue, sk);
 329         newsk = req->sk;
 330
 331         if (sk->sk_protocol == IPPROTO_TCP &&
 332             tcp_rsk(req)->tfo_listener) {
 333                 spin_lock_bh(&queue->fastopenq.lock);
 334                 if (tcp_rsk(req)->tfo_listener) {
 335                         /* We are still waiting for the final ACK from 3WHS
 336                          * so can't free req now. Instead, we set req->sk to
 337                          * NULL to signify that the child socket is taken
 338                          * so reqsk_fastopen_remove() will free the req
 339                          * when 3WHS finishes (or is aborted).
 340                          */
 341                         req->sk = NULL;
 342                         req = NULL;
 343                 }
 344                 spin_unlock_bh(&queue->fastopenq.lock);
 345         }
 346 out:
 347         release_sock(sk);
 348         if (req)
 349                 reqsk_put(req);
 350         return newsk;
 351 out_err:
 352         newsk = NULL;
 353         req = NULL;
 354         *err = error;
 355         goto out;
 356 }
 357 EXPORT_SYMBOL(inet_csk_accept);
 358
 359 /*
 360  * Using different timers for retransmit, delayed acks and probes
 361  * We may wish use just one timer maintaining a list of expire jiffies
 362  * to optimize.
 363  */
 364 void inet_csk_init_xmit_timers(struct sock *sk,
 365                                void (*retransmit_handler)(unsigned long),
 366                                void (*delack_handler)(unsigned long),
 367                                void (*keepalive_handler)(unsigned long))
 368 {
 369         struct inet_connection_sock *icsk = inet_csk(sk);
 370
 371         setup_timer(&icsk->icsk_retransmit_timer, retransmit_handler,
 372                         (unsigned long)sk);
 373         setup_timer(&icsk->icsk_delack_timer, delack_handler,
 374                         (unsigned long)sk);
 375         setup_timer(&sk->sk_timer, keepalive_handler, (unsigned long)sk);
 376         icsk->icsk_pending = icsk->icsk_ack.pending = 0;
 377 }
 378 EXPORT_SYMBOL(inet_csk_init_xmit_timers);
 379
 380 void inet_csk_clear_xmit_timers(struct sock *sk)
 381 {
 382         struct inet_connection_sock *icsk = inet_csk(sk);
 383
 384         icsk->icsk_pending = icsk->icsk_ack.pending = icsk->icsk_ack.blocked = 0;
 385
 386         sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
 387         sk_stop_timer(sk, &icsk->icsk_delack_timer);
 388         sk_stop_timer(sk, &sk->sk_timer);
 389 }
 390 EXPORT_SYMBOL(inet_csk_clear_xmit_timers);
 391
 392 void inet_csk_delete_keepalive_timer(struct sock *sk)
 393 {
 394         sk_stop_timer(sk, &sk->sk_timer);
 395 }
 396 EXPORT_SYMBOL(inet_csk_delete_keepalive_timer);
 397
 398 void inet_csk_reset_keepalive_timer(struct sock *sk, unsigned long len)
 399 {
 400         sk_reset_timer(sk, &sk->sk_timer, jiffies + len);
 401 }
 402 EXPORT_SYMBOL(inet_csk_reset_keepalive_timer);
 403
 404 struct dst_entry *inet_csk_route_req(const struct sock *sk,
 405                                      struct flowi4 *fl4,
 406                                      const struct request_sock *req)
 407 {
 408         const struct inet_request_sock *ireq = inet_rsk(req);
 409         struct net *net = read_pnet(&ireq->ireq_net);
 410         struct ip_options_rcu *opt = ireq->opt;
 411         struct rtable *rt;
 412
 413         flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
 414                            RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
 415                            sk->sk_protocol, inet_sk_flowi_flags(sk),
 416                            (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
 417                            ireq->ir_loc_addr, ireq->ir_rmt_port,
 418                            htons(ireq->ir_num));
 419         security_req_classify_flow(req, flowi4_to_flowi(fl4));
 420         rt = ip_route_output_flow(net, fl4, sk);
 421         if (IS_ERR(rt))
 422                 goto no_route;
 423         if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
 424                 goto route_err;
 425         return &rt->dst;
 426
 427 route_err:
 428         ip_rt_put(rt);
 429 no_route:
 430         __IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
 431         return NULL;
 432 }
 433 EXPORT_SYMBOL_GPL(inet_csk_route_req);
 434
 435 struct dst_entry *inet_csk_route_child_sock(const struct sock *sk,
 436                                             struct sock *newsk,
 437                                             const struct request_sock *req)
 438 {
 439         const struct inet_request_sock *ireq = inet_rsk(req);
 440         struct net *net = read_pnet(&ireq->ireq_net);
 441         struct inet_sock *newinet = inet_sk(newsk);
 442         struct ip_options_rcu *opt;
 443         struct flowi4 *fl4;
 444         struct rtable *rt;
 445
 446         fl4 = &newinet->cork.fl.u.ip4;
 447
 448         rcu_read_lock();
 449         opt = rcu_dereference(newinet->inet_opt);
 450         flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
 451                            RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
 452                            sk->sk_protocol, inet_sk_flowi_flags(sk),
 453                            (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
 454                            ireq->ir_loc_addr, ireq->ir_rmt_port,
 455                            htons(ireq->ir_num));
 456         security_req_classify_flow(req, flowi4_to_flowi(fl4));
 457         rt = ip_route_output_flow(net, fl4, sk);
 458         if (IS_ERR(rt))
 459                 goto no_route;
 460         if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
 461                 goto route_err;
 462         rcu_read_unlock();
 463         return &rt->dst;
 464
 465 route_err:
 466         ip_rt_put(rt);
 467 no_route:
 468         rcu_read_unlock();
 469         __IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
 470         return NULL;
 471 }
 472 EXPORT_SYMBOL_GPL(inet_csk_route_child_sock);
 473
 474 #if IS_ENABLED(CONFIG_IPV6)
 475 #define AF_INET_FAMILY(fam) ((fam) == AF_INET)
 476 #else
 477 #define AF_INET_FAMILY(fam) true
 478 #endif
 479
 480 /* Decide when to expire the request and when to resend SYN-ACK */
 481 static inline void syn_ack_recalc(struct request_sock *req, const int thresh,
 482                                   const int max_retries,
 483                                   const u8 rskq_defer_accept,
 484                                   int *expire, int *resend)
 485 {
 486         if (!rskq_defer_accept) {
 487                 *expire = req->num_timeout >= thresh;
 488                 *resend = 1;
 489                 return;
 490         }
 491         *expire = req->num_timeout >= thresh &&
 492                   (!inet_rsk(req)->acked || req->num_timeout >= max_retries);
 493         /*
 494          * Do not resend while waiting for data after ACK,
 495          * start to resend on end of deferring period to give
 496          * last chance for data or ACK to create established socket.
 497          */
 498         *resend = !inet_rsk(req)->acked ||
 499                   req->num_timeout >= rskq_defer_accept - 1;
 500 }
 501
 502 int inet_rtx_syn_ack(const struct sock *parent, struct request_sock *req)
 503 {
 504         int err = req->rsk_ops->rtx_syn_ack(parent, req);
 505
 506         if (!err)
 507                 req->num_retrans++;
 508         return err;
 509 }
 510 EXPORT_SYMBOL(inet_rtx_syn_ack);
 511
 512 /* return true if req was found in the ehash table */
 513 static bool reqsk_queue_unlink(struct request_sock_queue *queue,
 514                                struct request_sock *req)
 515 {
 516         struct inet_hashinfo *hashinfo = req_to_sk(req)->sk_prot->h.hashinfo;
 517         bool found = false;
 518
 519         if (sk_hashed(req_to_sk(req))) {
 520                 spinlock_t *lock = inet_ehash_lockp(hashinfo, req->rsk_hash);
 521
 522                 spin_lock(lock);
 523                 found = __sk_nulls_del_node_init_rcu(req_to_sk(req));
 524                 spin_unlock(lock);
 525         }
 526         if (timer_pending(&req->rsk_timer) && del_timer_sync(&req->rsk_timer))
 527                 reqsk_put(req);
 528         return found;
 529 }
 530
 531 void inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req)
 532 {
 533         if (reqsk_queue_unlink(&inet_csk(sk)->icsk_accept_queue, req)) {
 534                 reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req);
 535                 reqsk_put(req);
 536         }
 537 }
 538 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop);
 539
 540 void inet_csk_reqsk_queue_drop_and_put(struct sock *sk, struct request_sock *req)
 541 {
 542         inet_csk_reqsk_queue_drop(sk, req);
 543         reqsk_put(req);
 544 }
 545 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop_and_put);
 546
 547 static void reqsk_timer_handler(unsigned long data)
 548 {
 549         struct request_sock *req = (struct request_sock *)data;
 550         struct sock *sk_listener = req->rsk_listener;
 551         struct net *net = sock_net(sk_listener);
 552         struct inet_connection_sock *icsk = inet_csk(sk_listener);
 553         struct request_sock_queue *queue = &icsk->icsk_accept_queue;
 554         int qlen, expire = 0, resend = 0;
 555         int max_retries, thresh;
 556         u8 defer_accept;
 557
 558         if (sk_state_load(sk_listener) != TCP_LISTEN)
 559                 goto drop;
 560
 561         max_retries = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_synack_retries;
 562         thresh = max_retries;
 563         /* Normally all the openreqs are young and become mature
 564          * (i.e. converted to established socket) for first timeout.
 565          * If synack was not acknowledged for 1 second, it means
 566          * one of the following things: synack was lost, ack was lost,
 567          * rtt is high or nobody planned to ack (i.e. synflood).
 568          * When server is a bit loaded, queue is populated with old
 569          * open requests, reducing effective size of queue.
 570          * When server is well loaded, queue size reduces to zero
 571          * after several minutes of work. It is not synflood,
 572          * it is normal operation. The solution is pruning
 573          * too old entries overriding normal timeout, when
 574          * situation becomes dangerous.
 575          *
 576          * Essentially, we reserve half of room for young
 577          * embrions; and abort old ones without pity, if old
 578          * ones are about to clog our table.
 579          */
 580         qlen = reqsk_queue_len(queue);
 581         if ((qlen << 1) > max(8U, sk_listener->sk_max_ack_backlog)) {
 582                 int young = reqsk_queue_len_young(queue) << 1;
 583
 584                 while (thresh > 2) {
 585                         if (qlen < young)
 586                                 break;
 587                         thresh--;
 588                         young <<= 1;
 589                 }
 590         }
 591         defer_accept = READ_ONCE(queue->rskq_defer_accept);
 592         if (defer_accept)
 593                 max_retries = defer_accept;
 594         syn_ack_recalc(req, thresh, max_retries, defer_accept,
 595                        &expire, &resend);
 596         req->rsk_ops->syn_ack_timeout(req);
 597         if (!expire &&
 598             (!resend ||
 599              !inet_rtx_syn_ack(sk_listener, req) ||
 600              inet_rsk(req)->acked)) {
 601                 unsigned long timeo;
 602
 603                 if (req->num_timeout++ == 0)
 604                         atomic_dec(&queue->young);
 605                 timeo = min(TCP_TIMEOUT_INIT << req->num_timeout, TCP_RTO_MAX);
 606                 mod_timer(&req->rsk_timer, jiffies + timeo);
 607                 return;
 608         }
 609 drop:
 610         inet_csk_reqsk_queue_drop_and_put(sk_listener, req);
 611 }
 612
 613 static void reqsk_queue_hash_req(struct request_sock *req,
 614                                  unsigned long timeout)
 615 {
 616         req->num_retrans = 0;
 617         req->num_timeout = 0;
 618         req->sk = NULL;
 619
 620         setup_pinned_timer(&req->rsk_timer, reqsk_timer_handler,
 621                             (unsigned long)req);
 622         mod_timer(&req->rsk_timer, jiffies + timeout);
 623
 624         inet_ehash_insert(req_to_sk(req), NULL);
 625         /* before letting lookups find us, make sure all req fields
 626          * are committed to memory and refcnt initialized.
 627          */
 628         smp_wmb();
 629         atomic_set(&req->rsk_refcnt, 2 + 1);
 630 }
 631
 632 void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
 633                                    unsigned long timeout)
 634 {
 635         reqsk_queue_hash_req(req, timeout);
 636         inet_csk_reqsk_queue_added(sk);
 637 }
 638 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add);
 639
 640 /**
 641  *      inet_csk_clone_lock - clone an inet socket, and lock its clone
 642  *      @sk: the socket to clone
 643  *      @req: request_sock
 644  *      @priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc)
 645  *
 646  *      Caller must unlock socket even in error path (bh_unlock_sock(newsk))
 647  */
 648 struct sock *inet_csk_clone_lock(const struct sock *sk,
 649                                  const struct request_sock *req,
 650                                  const gfp_t priority)
 651 {
 652         struct sock *newsk = sk_clone_lock(sk, priority);
 653
 654         if (newsk) {
 655                 struct inet_connection_sock *newicsk = inet_csk(newsk);
 656
 657                 newsk->sk_state = TCP_SYN_RECV;
 658                 newicsk->icsk_bind_hash = NULL;
 659
 660                 inet_sk(newsk)->inet_dport = inet_rsk(req)->ir_rmt_port;
 661                 inet_sk(newsk)->inet_num = inet_rsk(req)->ir_num;
 662                 inet_sk(newsk)->inet_sport = htons(inet_rsk(req)->ir_num);
 663                 newsk->sk_write_space = sk_stream_write_space;
 664
 665                 /* listeners have SOCK_RCU_FREE, not the children */
 666                 sock_reset_flag(newsk, SOCK_RCU_FREE);
 667
 668                 newsk->sk_mark = inet_rsk(req)->ir_mark;
 669                 atomic64_set(&newsk->sk_cookie,
 670                              atomic64_read(&inet_rsk(req)->ir_cookie));
 671
 672                 newicsk->icsk_retransmits = 0;
 673                 newicsk->icsk_backoff     = 0;
 674                 newicsk->icsk_probes_out  = 0;
 675
 676                 /* Deinitialize accept_queue to trap illegal accesses. */
 677                 memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue));
 678
 679                 security_inet_csk_clone(newsk, req);
 680         }
 681         return newsk;
 682 }
 683 EXPORT_SYMBOL_GPL(inet_csk_clone_lock);
 684
 685 /*
 686  * At this point, there should be no process reference to this
 687  * socket, and thus no user references at all.  Therefore we
 688  * can assume the socket waitqueue is inactive and nobody will
 689  * try to jump onto it.
 690  */
 691 void inet_csk_destroy_sock(struct sock *sk)
 692 {
 693         WARN_ON(sk->sk_state != TCP_CLOSE);
 694         WARN_ON(!sock_flag(sk, SOCK_DEAD));
 695
 696         /* It cannot be in hash table! */
 697         WARN_ON(!sk_unhashed(sk));
 698
 699         /* If it has not 0 inet_sk(sk)->inet_num, it must be bound */
 700         WARN_ON(inet_sk(sk)->inet_num && !inet_csk(sk)->icsk_bind_hash);
 701
 702         sk->sk_prot->destroy(sk);
 703
 704         sk_stream_kill_queues(sk);
 705
 706         xfrm_sk_free_policy(sk);
 707
 708         sk_refcnt_debug_release(sk);
 709
 710         local_bh_disable();
 711         percpu_counter_dec(sk->sk_prot->orphan_count);
 712         local_bh_enable();
 713         sock_put(sk);
 714 }
 715 EXPORT_SYMBOL(inet_csk_destroy_sock);
 716
 717 /* This function allows to force a closure of a socket after the call to
 718  * tcp/dccp_create_openreq_child().
 719  */
 720 void inet_csk_prepare_forced_close(struct sock *sk)
 721         __releases(&sk->sk_lock.slock)
 722 {
 723         /* sk_clone_lock locked the socket and set refcnt to 2 */
 724         bh_unlock_sock(sk);
 725         sock_put(sk);
 726
 727         /* The below has to be done to allow calling inet_csk_destroy_sock */
 728         sock_set_flag(sk, SOCK_DEAD);
 729         percpu_counter_inc(sk->sk_prot->orphan_count);
 730         inet_sk(sk)->inet_num = 0;
 731 }
 732 EXPORT_SYMBOL(inet_csk_prepare_forced_close);
 733
 734 int inet_csk_listen_start(struct sock *sk, int backlog)
 735 {
 736         struct inet_connection_sock *icsk = inet_csk(sk);
 737         struct inet_sock *inet = inet_sk(sk);
 738         int err = -EADDRINUSE;
 739
 740         reqsk_queue_alloc(&icsk->icsk_accept_queue);
 741
 742         sk->sk_max_ack_backlog = backlog;
 743         sk->sk_ack_backlog = 0;
 744         inet_csk_delack_init(sk);
 745
 746         /* There is race window here: we announce ourselves listening,
 747          * but this transition is still not validated by get_port().
 748          * It is OK, because this socket enters to hash table only
 749          * after validation is complete.
 750          */
 751         sk_state_store(sk, TCP_LISTEN);
 752         if (!sk->sk_prot->get_port(sk, inet->inet_num)) {
 753                 inet->inet_sport = htons(inet->inet_num);
 754
 755                 sk_dst_reset(sk);
 756                 err = sk->sk_prot->hash(sk);
 757
 758                 if (likely(!err))
 759                         return 0;
 760         }
 761
 762         sk->sk_state = TCP_CLOSE;
 763         return err;
 764 }
 765 EXPORT_SYMBOL_GPL(inet_csk_listen_start);
 766
 767 static void inet_child_forget(struct sock *sk, struct request_sock *req,
 768                               struct sock *child)
 769 {
 770         sk->sk_prot->disconnect(child, O_NONBLOCK);
 771
 772         sock_orphan(child);
 773
 774         percpu_counter_inc(sk->sk_prot->orphan_count);
 775
 776         if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(req)->tfo_listener) {
 777                 BUG_ON(tcp_sk(child)->fastopen_rsk != req);
 778                 BUG_ON(sk != req->rsk_listener);
 779
 780                 /* Paranoid, to prevent race condition if
 781                  * an inbound pkt destined for child is
 782                  * blocked by sock lock in tcp_v4_rcv().
 783                  * Also to satisfy an assertion in
 784                  * tcp_v4_destroy_sock().
 785                  */
 786                 tcp_sk(child)->fastopen_rsk = NULL;
 787         }
 788         inet_csk_destroy_sock(child);
 789         reqsk_put(req);
 790 }
 791
 792 struct sock *inet_csk_reqsk_queue_add(struct sock *sk,
 793                                       struct request_sock *req,
 794                                       struct sock *child)
 795 {
 796         struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
 797
 798         spin_lock(&queue->rskq_lock);
 799         if (unlikely(sk->sk_state != TCP_LISTEN)) {
 800                 inet_child_forget(sk, req, child);
 801                 child = NULL;
 802         } else {
 803                 req->sk = child;
 804                 req->dl_next = NULL;
 805                 if (queue->rskq_accept_head == NULL)
 806                         queue->rskq_accept_head = req;
 807                 else
 808                         queue->rskq_accept_tail->dl_next = req;
 809                 queue->rskq_accept_tail = req;
 810                 sk_acceptq_added(sk);
 811         }
 812         spin_unlock(&queue->rskq_lock);
 813         return child;
 814 }
 815 EXPORT_SYMBOL(inet_csk_reqsk_queue_add);
 816
 817 struct sock *inet_csk_complete_hashdance(struct sock *sk, struct sock *child,
 818                                          struct request_sock *req, bool own_req)
 819 {
 820         if (own_req) {
 821                 inet_csk_reqsk_queue_drop(sk, req);
 822                 reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req);
 823                 if (inet_csk_reqsk_queue_add(sk, req, child))
 824                         return child;
 825         }
 826         /* Too bad, another child took ownership of the request, undo. */
 827         bh_unlock_sock(child);
 828         sock_put(child);
 829         return NULL;
 830 }
 831 EXPORT_SYMBOL(inet_csk_complete_hashdance);
 832
 833 /*
 834  *      This routine closes sockets which have been at least partially
 835  *      opened, but not yet accepted.
 836  */
 837 void inet_csk_listen_stop(struct sock *sk)
 838 {
 839         struct inet_connection_sock *icsk = inet_csk(sk);
 840         struct request_sock_queue *queue = &icsk->icsk_accept_queue;
 841         struct request_sock *next, *req;
 842
 843         /* Following specs, it would be better either to send FIN
 844          * (and enter FIN-WAIT-1, it is normal close)
 845          * or to send active reset (abort).
 846          * Certainly, it is pretty dangerous while synflood, but it is
 847          * bad justification for our negligence 8)
 848          * To be honest, we are not able to make either
 849          * of the variants now.                 --ANK
 850          */
 851         while ((req = reqsk_queue_remove(queue, sk)) != NULL) {
 852                 struct sock *child = req->sk;
 853
 854                 local_bh_disable();
 855                 bh_lock_sock(child);
 856                 WARN_ON(sock_owned_by_user(child));
 857                 sock_hold(child);
 858
 859                 inet_child_forget(sk, req, child);
 860                 bh_unlock_sock(child);
 861                 local_bh_enable();
 862                 sock_put(child);
 863
 864                 cond_resched();
 865         }
 866         if (queue->fastopenq.rskq_rst_head) {
 867                 /* Free all the reqs queued in rskq_rst_head. */
 868                 spin_lock_bh(&queue->fastopenq.lock);
 869                 req = queue->fastopenq.rskq_rst_head;
 870                 queue->fastopenq.rskq_rst_head = NULL;
 871                 spin_unlock_bh(&queue->fastopenq.lock);
 872                 while (req != NULL) {
 873                         next = req->dl_next;
 874                         reqsk_put(req);
 875                         req = next;
 876                 }
 877         }
 878         WARN_ON_ONCE(sk->sk_ack_backlog);
 879 }
 880 EXPORT_SYMBOL_GPL(inet_csk_listen_stop);
 881
 882 void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr)
 883 {
 884         struct sockaddr_in *sin = (struct sockaddr_in *)uaddr;
 885         const struct inet_sock *inet = inet_sk(sk);
 886
 887         sin->sin_family         = AF_INET;
 888         sin->sin_addr.s_addr    = inet->inet_daddr;
 889         sin->sin_port           = inet->inet_dport;
 890 }
 891 EXPORT_SYMBOL_GPL(inet_csk_addr2sockaddr);
 892
 893 #ifdef CONFIG_COMPAT
 894 int inet_csk_compat_getsockopt(struct sock *sk, int level, int optname,
 895                                char __user *optval, int __user *optlen)
 896 {
 897         const struct inet_connection_sock *icsk = inet_csk(sk);
 898
 899         if (icsk->icsk_af_ops->compat_getsockopt)
 900                 return icsk->icsk_af_ops->compat_getsockopt(sk, level, optname,
 901                                                             optval, optlen);
 902         return icsk->icsk_af_ops->getsockopt(sk, level, optname,
 903                                              optval, optlen);
 904 }
 905 EXPORT_SYMBOL_GPL(inet_csk_compat_getsockopt);
 906
 907 int inet_csk_compat_setsockopt(struct sock *sk, int level, int optname,
 908                                char __user *optval, unsigned int optlen)
 909 {
 910         const struct inet_connection_sock *icsk = inet_csk(sk);
 911
 912         if (icsk->icsk_af_ops->compat_setsockopt)
 913                 return icsk->icsk_af_ops->compat_setsockopt(sk, level, optname,
 914                                                             optval, optlen);
 915         return icsk->icsk_af_ops->setsockopt(sk, level, optname,
 916                                              optval, optlen);
 917 }
 918 EXPORT_SYMBOL_GPL(inet_csk_compat_setsockopt);
 919 #endif
 920
 921 static struct dst_entry *inet_csk_rebuild_route(struct sock *sk, struct flowi *fl)
 922 {
 923         const struct inet_sock *inet = inet_sk(sk);
 924         const struct ip_options_rcu *inet_opt;
 925         __be32 daddr = inet->inet_daddr;
 926         struct flowi4 *fl4;
 927         struct rtable *rt;
 928
 929         rcu_read_lock();
 930         inet_opt = rcu_dereference(inet->inet_opt);
 931         if (inet_opt && inet_opt->opt.srr)
 932                 daddr = inet_opt->opt.faddr;
 933         fl4 = &fl->u.ip4;
 934         rt = ip_route_output_ports(sock_net(sk), fl4, sk, daddr,
 935                                    inet->inet_saddr, inet->inet_dport,
 936                                    inet->inet_sport, sk->sk_protocol,
 937                                    RT_CONN_FLAGS(sk), sk->sk_bound_dev_if);
 938         if (IS_ERR(rt))
 939                 rt = NULL;
 940         if (rt)
 941                 sk_setup_caps(sk, &rt->dst);
 942         rcu_read_unlock();
 943
 944         return &rt->dst;
 945 }
 946
 947 struct dst_entry *inet_csk_update_pmtu(struct sock *sk, u32 mtu)
 948 {
 949         struct dst_entry *dst = __sk_dst_check(sk, 0);
 950         struct inet_sock *inet = inet_sk(sk);
 951
 952         if (!dst) {
 953                 dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
 954                 if (!dst)
 955                         goto out;
 956         }
 957         dst->ops->update_pmtu(dst, sk, NULL, mtu);
 958
 959         dst = __sk_dst_check(sk, 0);
 960         if (!dst)
 961                 dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
 962 out:
 963         return dst;
 964 }
 965 EXPORT_SYMBOL_GPL(inet_csk_update_pmtu);