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 #include <net/addrconf.h> 29 30 #if IS_ENABLED(CONFIG_IPV6) 31 /* match_wildcard == true: IPV6_ADDR_ANY equals to any IPv6 addresses if IPv6 32 * only, and any IPv4 addresses if not IPv6 only 33 * match_wildcard == false: addresses must be exactly the same, i.e. 34 * IPV6_ADDR_ANY only equals to IPV6_ADDR_ANY, 35 * and 0.0.0.0 equals to 0.0.0.0 only 36 */ 37 static bool ipv6_rcv_saddr_equal(const struct in6_addr *sk1_rcv_saddr6, 38 const struct in6_addr *sk2_rcv_saddr6, 39 __be32 sk1_rcv_saddr, __be32 sk2_rcv_saddr, 40 bool sk1_ipv6only, bool sk2_ipv6only, 41 bool match_wildcard) 42 { 43 int addr_type = ipv6_addr_type(sk1_rcv_saddr6); 44 int addr_type2 = sk2_rcv_saddr6 ? ipv6_addr_type(sk2_rcv_saddr6) : IPV6_ADDR_MAPPED; 45 46 /* if both are mapped, treat as IPv4 */ 47 if (addr_type == IPV6_ADDR_MAPPED && addr_type2 == IPV6_ADDR_MAPPED) { 48 if (!sk2_ipv6only) { 49 if (sk1_rcv_saddr == sk2_rcv_saddr) 50 return true; 51 if (!sk1_rcv_saddr || !sk2_rcv_saddr) 52 return match_wildcard; 53 } 54 return false; 55 } 56 57 if (addr_type == IPV6_ADDR_ANY && addr_type2 == IPV6_ADDR_ANY) 58 return true; 59 60 if (addr_type2 == IPV6_ADDR_ANY && match_wildcard && 61 !(sk2_ipv6only && addr_type == IPV6_ADDR_MAPPED)) 62 return true; 63 64 if (addr_type == IPV6_ADDR_ANY && match_wildcard && 65 !(sk1_ipv6only && addr_type2 == IPV6_ADDR_MAPPED)) 66 return true; 67 68 if (sk2_rcv_saddr6 && 69 ipv6_addr_equal(sk1_rcv_saddr6, sk2_rcv_saddr6)) 70 return true; 71 72 return false; 73 } 74 #endif 75 76 /* match_wildcard == true: 0.0.0.0 equals to any IPv4 addresses 77 * match_wildcard == false: addresses must be exactly the same, i.e. 78 * 0.0.0.0 only equals to 0.0.0.0 79 */ 80 static bool ipv4_rcv_saddr_equal(__be32 sk1_rcv_saddr, __be32 sk2_rcv_saddr, 81 bool sk2_ipv6only, bool match_wildcard) 82 { 83 if (!sk2_ipv6only) { 84 if (sk1_rcv_saddr == sk2_rcv_saddr) 85 return true; 86 if (!sk1_rcv_saddr || !sk2_rcv_saddr) 87 return match_wildcard; 88 } 89 return false; 90 } 91 92 bool inet_rcv_saddr_equal(const struct sock *sk, const struct sock *sk2, 93 bool match_wildcard) 94 { 95 #if IS_ENABLED(CONFIG_IPV6) 96 if (sk->sk_family == AF_INET6) 97 return ipv6_rcv_saddr_equal(&sk->sk_v6_rcv_saddr, 98 inet6_rcv_saddr(sk2), 99 sk->sk_rcv_saddr, 100 sk2->sk_rcv_saddr, 101 ipv6_only_sock(sk), 102 ipv6_only_sock(sk2), 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 } 108 EXPORT_SYMBOL(inet_rcv_saddr_equal); 109 110 void inet_get_local_port_range(struct net *net, int *low, int *high) 111 { 112 unsigned int seq; 113 114 do { 115 seq = read_seqbegin(&net->ipv4.ip_local_ports.lock); 116 117 *low = net->ipv4.ip_local_ports.range[0]; 118 *high = net->ipv4.ip_local_ports.range[1]; 119 } while (read_seqretry(&net->ipv4.ip_local_ports.lock, seq)); 120 } 121 EXPORT_SYMBOL(inet_get_local_port_range); 122 123 static int inet_csk_bind_conflict(const struct sock *sk, 124 const struct inet_bind_bucket *tb, 125 bool relax, bool reuseport_ok) 126 { 127 struct sock *sk2; 128 bool reuse = sk->sk_reuse; 129 bool reuseport = !!sk->sk_reuseport && reuseport_ok; 130 kuid_t uid = sock_i_uid((struct sock *)sk); 131 132 /* 133 * Unlike other sk lookup places we do not check 134 * for sk_net here, since _all_ the socks listed 135 * in tb->owners list belong to the same net - the 136 * one this bucket belongs to. 137 */ 138 139 sk_for_each_bound(sk2, &tb->owners) { 140 if (sk != sk2 && 141 (!sk->sk_bound_dev_if || 142 !sk2->sk_bound_dev_if || 143 sk->sk_bound_dev_if == sk2->sk_bound_dev_if)) { 144 if ((!reuse || !sk2->sk_reuse || 145 sk2->sk_state == TCP_LISTEN) && 146 (!reuseport || !sk2->sk_reuseport || 147 rcu_access_pointer(sk->sk_reuseport_cb) || 148 (sk2->sk_state != TCP_TIME_WAIT && 149 !uid_eq(uid, sock_i_uid(sk2))))) { 150 if (inet_rcv_saddr_equal(sk, sk2, true)) 151 break; 152 } 153 if (!relax && reuse && sk2->sk_reuse && 154 sk2->sk_state != TCP_LISTEN) { 155 if (inet_rcv_saddr_equal(sk, sk2, true)) 156 break; 157 } 158 } 159 } 160 return sk2 != NULL; 161 } 162 163 /* 164 * Find an open port number for the socket. Returns with the 165 * inet_bind_hashbucket lock held. 166 */ 167 static struct inet_bind_hashbucket * 168 inet_csk_find_open_port(struct sock *sk, struct inet_bind_bucket **tb_ret, int *port_ret) 169 { 170 struct inet_hashinfo *hinfo = sk->sk_prot->h.hashinfo; 171 int port = 0; 172 struct inet_bind_hashbucket *head; 173 struct net *net = sock_net(sk); 174 int i, low, high, attempt_half; 175 struct inet_bind_bucket *tb; 176 u32 remaining, offset; 177 178 attempt_half = (sk->sk_reuse == SK_CAN_REUSE) ? 1 : 0; 179 other_half_scan: 180 inet_get_local_port_range(net, &low, &high); 181 high++; /* [32768, 60999] -> [32768, 61000[ */ 182 if (high - low < 4) 183 attempt_half = 0; 184 if (attempt_half) { 185 int half = low + (((high - low) >> 2) << 1); 186 187 if (attempt_half == 1) 188 high = half; 189 else 190 low = half; 191 } 192 remaining = high - low; 193 if (likely(remaining > 1)) 194 remaining &= ~1U; 195 196 offset = prandom_u32() % remaining; 197 /* __inet_hash_connect() favors ports having @low parity 198 * We do the opposite to not pollute connect() users. 199 */ 200 offset |= 1U; 201 202 other_parity_scan: 203 port = low + offset; 204 for (i = 0; i < remaining; i += 2, port += 2) { 205 if (unlikely(port >= high)) 206 port -= remaining; 207 if (inet_is_local_reserved_port(net, port)) 208 continue; 209 head = &hinfo->bhash[inet_bhashfn(net, port, 210 hinfo->bhash_size)]; 211 spin_lock_bh(&head->lock); 212 inet_bind_bucket_for_each(tb, &head->chain) 213 if (net_eq(ib_net(tb), net) && tb->port == port) { 214 if (!inet_csk_bind_conflict(sk, tb, false, false)) 215 goto success; 216 goto next_port; 217 } 218 tb = NULL; 219 goto success; 220 next_port: 221 spin_unlock_bh(&head->lock); 222 cond_resched(); 223 } 224 225 offset--; 226 if (!(offset & 1)) 227 goto other_parity_scan; 228 229 if (attempt_half == 1) { 230 /* OK we now try the upper half of the range */ 231 attempt_half = 2; 232 goto other_half_scan; 233 } 234 return NULL; 235 success: 236 *port_ret = port; 237 *tb_ret = tb; 238 return head; 239 } 240 241 static inline int sk_reuseport_match(struct inet_bind_bucket *tb, 242 struct sock *sk) 243 { 244 kuid_t uid = sock_i_uid(sk); 245 246 if (tb->fastreuseport <= 0) 247 return 0; 248 if (!sk->sk_reuseport) 249 return 0; 250 if (rcu_access_pointer(sk->sk_reuseport_cb)) 251 return 0; 252 if (!uid_eq(tb->fastuid, uid)) 253 return 0; 254 /* We only need to check the rcv_saddr if this tb was once marked 255 * without fastreuseport and then was reset, as we can only know that 256 * the fast_*rcv_saddr doesn't have any conflicts with the socks on the 257 * owners list. 258 */ 259 if (tb->fastreuseport == FASTREUSEPORT_ANY) 260 return 1; 261 #if IS_ENABLED(CONFIG_IPV6) 262 if (tb->fast_sk_family == AF_INET6) 263 return ipv6_rcv_saddr_equal(&tb->fast_v6_rcv_saddr, 264 inet6_rcv_saddr(sk), 265 tb->fast_rcv_saddr, 266 sk->sk_rcv_saddr, 267 tb->fast_ipv6_only, 268 ipv6_only_sock(sk), true); 269 #endif 270 return ipv4_rcv_saddr_equal(tb->fast_rcv_saddr, sk->sk_rcv_saddr, 271 ipv6_only_sock(sk), true); 272 } 273 274 /* Obtain a reference to a local port for the given sock, 275 * if snum is zero it means select any available local port. 276 * We try to allocate an odd port (and leave even ports for connect()) 277 */ 278 int inet_csk_get_port(struct sock *sk, unsigned short snum) 279 { 280 bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN; 281 struct inet_hashinfo *hinfo = sk->sk_prot->h.hashinfo; 282 int ret = 1, port = snum; 283 struct inet_bind_hashbucket *head; 284 struct net *net = sock_net(sk); 285 struct inet_bind_bucket *tb = NULL; 286 kuid_t uid = sock_i_uid(sk); 287 288 if (!port) { 289 head = inet_csk_find_open_port(sk, &tb, &port); 290 if (!head) 291 return ret; 292 if (!tb) 293 goto tb_not_found; 294 goto success; 295 } 296 head = &hinfo->bhash[inet_bhashfn(net, port, 297 hinfo->bhash_size)]; 298 spin_lock_bh(&head->lock); 299 inet_bind_bucket_for_each(tb, &head->chain) 300 if (net_eq(ib_net(tb), net) && tb->port == port) 301 goto tb_found; 302 tb_not_found: 303 tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep, 304 net, head, port); 305 if (!tb) 306 goto fail_unlock; 307 tb_found: 308 if (!hlist_empty(&tb->owners)) { 309 if (sk->sk_reuse == SK_FORCE_REUSE) 310 goto success; 311 312 if ((tb->fastreuse > 0 && reuse) || 313 sk_reuseport_match(tb, sk)) 314 goto success; 315 if (inet_csk_bind_conflict(sk, tb, true, true)) 316 goto fail_unlock; 317 } 318 success: 319 if (hlist_empty(&tb->owners)) { 320 tb->fastreuse = reuse; 321 if (sk->sk_reuseport) { 322 tb->fastreuseport = FASTREUSEPORT_ANY; 323 tb->fastuid = uid; 324 tb->fast_rcv_saddr = sk->sk_rcv_saddr; 325 tb->fast_ipv6_only = ipv6_only_sock(sk); 326 tb->fast_sk_family = sk->sk_family; 327 #if IS_ENABLED(CONFIG_IPV6) 328 tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr; 329 #endif 330 } else { 331 tb->fastreuseport = 0; 332 } 333 } else { 334 if (!reuse) 335 tb->fastreuse = 0; 336 if (sk->sk_reuseport) { 337 /* We didn't match or we don't have fastreuseport set on 338 * the tb, but we have sk_reuseport set on this socket 339 * and we know that there are no bind conflicts with 340 * this socket in this tb, so reset our tb's reuseport 341 * settings so that any subsequent sockets that match 342 * our current socket will be put on the fast path. 343 * 344 * If we reset we need to set FASTREUSEPORT_STRICT so we 345 * do extra checking for all subsequent sk_reuseport 346 * socks. 347 */ 348 if (!sk_reuseport_match(tb, sk)) { 349 tb->fastreuseport = FASTREUSEPORT_STRICT; 350 tb->fastuid = uid; 351 tb->fast_rcv_saddr = sk->sk_rcv_saddr; 352 tb->fast_ipv6_only = ipv6_only_sock(sk); 353 tb->fast_sk_family = sk->sk_family; 354 #if IS_ENABLED(CONFIG_IPV6) 355 tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr; 356 #endif 357 } 358 } else { 359 tb->fastreuseport = 0; 360 } 361 } 362 if (!inet_csk(sk)->icsk_bind_hash) 363 inet_bind_hash(sk, tb, port); 364 WARN_ON(inet_csk(sk)->icsk_bind_hash != tb); 365 ret = 0; 366 367 fail_unlock: 368 spin_unlock_bh(&head->lock); 369 return ret; 370 } 371 EXPORT_SYMBOL_GPL(inet_csk_get_port); 372 373 /* 374 * Wait for an incoming connection, avoid race conditions. This must be called 375 * with the socket locked. 376 */ 377 static int inet_csk_wait_for_connect(struct sock *sk, long timeo) 378 { 379 struct inet_connection_sock *icsk = inet_csk(sk); 380 DEFINE_WAIT(wait); 381 int err; 382 383 /* 384 * True wake-one mechanism for incoming connections: only 385 * one process gets woken up, not the 'whole herd'. 386 * Since we do not 'race & poll' for established sockets 387 * anymore, the common case will execute the loop only once. 388 * 389 * Subtle issue: "add_wait_queue_exclusive()" will be added 390 * after any current non-exclusive waiters, and we know that 391 * it will always _stay_ after any new non-exclusive waiters 392 * because all non-exclusive waiters are added at the 393 * beginning of the wait-queue. As such, it's ok to "drop" 394 * our exclusiveness temporarily when we get woken up without 395 * having to remove and re-insert us on the wait queue. 396 */ 397 for (;;) { 398 prepare_to_wait_exclusive(sk_sleep(sk), &wait, 399 TASK_INTERRUPTIBLE); 400 release_sock(sk); 401 if (reqsk_queue_empty(&icsk->icsk_accept_queue)) 402 timeo = schedule_timeout(timeo); 403 sched_annotate_sleep(); 404 lock_sock(sk); 405 err = 0; 406 if (!reqsk_queue_empty(&icsk->icsk_accept_queue)) 407 break; 408 err = -EINVAL; 409 if (sk->sk_state != TCP_LISTEN) 410 break; 411 err = sock_intr_errno(timeo); 412 if (signal_pending(current)) 413 break; 414 err = -EAGAIN; 415 if (!timeo) 416 break; 417 } 418 finish_wait(sk_sleep(sk), &wait); 419 return err; 420 } 421 422 /* 423 * This will accept the next outstanding connection. 424 */ 425 struct sock *inet_csk_accept(struct sock *sk, int flags, int *err, bool kern) 426 { 427 struct inet_connection_sock *icsk = inet_csk(sk); 428 struct request_sock_queue *queue = &icsk->icsk_accept_queue; 429 struct request_sock *req; 430 struct sock *newsk; 431 int error; 432 433 lock_sock(sk); 434 435 /* We need to make sure that this socket is listening, 436 * and that it has something pending. 437 */ 438 error = -EINVAL; 439 if (sk->sk_state != TCP_LISTEN) 440 goto out_err; 441 442 /* Find already established connection */ 443 if (reqsk_queue_empty(queue)) { 444 long timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK); 445 446 /* If this is a non blocking socket don't sleep */ 447 error = -EAGAIN; 448 if (!timeo) 449 goto out_err; 450 451 error = inet_csk_wait_for_connect(sk, timeo); 452 if (error) 453 goto out_err; 454 } 455 req = reqsk_queue_remove(queue, sk); 456 newsk = req->sk; 457 458 if (sk->sk_protocol == IPPROTO_TCP && 459 tcp_rsk(req)->tfo_listener) { 460 spin_lock_bh(&queue->fastopenq.lock); 461 if (tcp_rsk(req)->tfo_listener) { 462 /* We are still waiting for the final ACK from 3WHS 463 * so can't free req now. Instead, we set req->sk to 464 * NULL to signify that the child socket is taken 465 * so reqsk_fastopen_remove() will free the req 466 * when 3WHS finishes (or is aborted). 467 */ 468 req->sk = NULL; 469 req = NULL; 470 } 471 spin_unlock_bh(&queue->fastopenq.lock); 472 } 473 out: 474 release_sock(sk); 475 if (req) 476 reqsk_put(req); 477 return newsk; 478 out_err: 479 newsk = NULL; 480 req = NULL; 481 *err = error; 482 goto out; 483 } 484 EXPORT_SYMBOL(inet_csk_accept); 485 486 /* 487 * Using different timers for retransmit, delayed acks and probes 488 * We may wish use just one timer maintaining a list of expire jiffies 489 * to optimize. 490 */ 491 void inet_csk_init_xmit_timers(struct sock *sk, 492 void (*retransmit_handler)(struct timer_list *t), 493 void (*delack_handler)(struct timer_list *t), 494 void (*keepalive_handler)(struct timer_list *t)) 495 { 496 struct inet_connection_sock *icsk = inet_csk(sk); 497 498 timer_setup(&icsk->icsk_retransmit_timer, retransmit_handler, 0); 499 timer_setup(&icsk->icsk_delack_timer, delack_handler, 0); 500 timer_setup(&sk->sk_timer, keepalive_handler, 0); 501 icsk->icsk_pending = icsk->icsk_ack.pending = 0; 502 } 503 EXPORT_SYMBOL(inet_csk_init_xmit_timers); 504 505 void inet_csk_clear_xmit_timers(struct sock *sk) 506 { 507 struct inet_connection_sock *icsk = inet_csk(sk); 508 509 icsk->icsk_pending = icsk->icsk_ack.pending = icsk->icsk_ack.blocked = 0; 510 511 sk_stop_timer(sk, &icsk->icsk_retransmit_timer); 512 sk_stop_timer(sk, &icsk->icsk_delack_timer); 513 sk_stop_timer(sk, &sk->sk_timer); 514 } 515 EXPORT_SYMBOL(inet_csk_clear_xmit_timers); 516 517 void inet_csk_delete_keepalive_timer(struct sock *sk) 518 { 519 sk_stop_timer(sk, &sk->sk_timer); 520 } 521 EXPORT_SYMBOL(inet_csk_delete_keepalive_timer); 522 523 void inet_csk_reset_keepalive_timer(struct sock *sk, unsigned long len) 524 { 525 sk_reset_timer(sk, &sk->sk_timer, jiffies + len); 526 } 527 EXPORT_SYMBOL(inet_csk_reset_keepalive_timer); 528 529 struct dst_entry *inet_csk_route_req(const struct sock *sk, 530 struct flowi4 *fl4, 531 const struct request_sock *req) 532 { 533 const struct inet_request_sock *ireq = inet_rsk(req); 534 struct net *net = read_pnet(&ireq->ireq_net); 535 struct ip_options_rcu *opt; 536 struct rtable *rt; 537 538 opt = ireq_opt_deref(ireq); 539 540 flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark, 541 RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE, 542 sk->sk_protocol, inet_sk_flowi_flags(sk), 543 (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr, 544 ireq->ir_loc_addr, ireq->ir_rmt_port, 545 htons(ireq->ir_num), sk->sk_uid); 546 security_req_classify_flow(req, flowi4_to_flowi(fl4)); 547 rt = ip_route_output_flow(net, fl4, sk); 548 if (IS_ERR(rt)) 549 goto no_route; 550 if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway) 551 goto route_err; 552 return &rt->dst; 553 554 route_err: 555 ip_rt_put(rt); 556 no_route: 557 __IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES); 558 return NULL; 559 } 560 EXPORT_SYMBOL_GPL(inet_csk_route_req); 561 562 struct dst_entry *inet_csk_route_child_sock(const struct sock *sk, 563 struct sock *newsk, 564 const struct request_sock *req) 565 { 566 const struct inet_request_sock *ireq = inet_rsk(req); 567 struct net *net = read_pnet(&ireq->ireq_net); 568 struct inet_sock *newinet = inet_sk(newsk); 569 struct ip_options_rcu *opt; 570 struct flowi4 *fl4; 571 struct rtable *rt; 572 573 opt = rcu_dereference(ireq->ireq_opt); 574 fl4 = &newinet->cork.fl.u.ip4; 575 576 flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark, 577 RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE, 578 sk->sk_protocol, inet_sk_flowi_flags(sk), 579 (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr, 580 ireq->ir_loc_addr, ireq->ir_rmt_port, 581 htons(ireq->ir_num), sk->sk_uid); 582 security_req_classify_flow(req, flowi4_to_flowi(fl4)); 583 rt = ip_route_output_flow(net, fl4, sk); 584 if (IS_ERR(rt)) 585 goto no_route; 586 if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway) 587 goto route_err; 588 return &rt->dst; 589 590 route_err: 591 ip_rt_put(rt); 592 no_route: 593 __IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES); 594 return NULL; 595 } 596 EXPORT_SYMBOL_GPL(inet_csk_route_child_sock); 597 598 #if IS_ENABLED(CONFIG_IPV6) 599 #define AF_INET_FAMILY(fam) ((fam) == AF_INET) 600 #else 601 #define AF_INET_FAMILY(fam) true 602 #endif 603 604 /* Decide when to expire the request and when to resend SYN-ACK */ 605 static inline void syn_ack_recalc(struct request_sock *req, const int thresh, 606 const int max_retries, 607 const u8 rskq_defer_accept, 608 int *expire, int *resend) 609 { 610 if (!rskq_defer_accept) { 611 *expire = req->num_timeout >= thresh; 612 *resend = 1; 613 return; 614 } 615 *expire = req->num_timeout >= thresh && 616 (!inet_rsk(req)->acked || req->num_timeout >= max_retries); 617 /* 618 * Do not resend while waiting for data after ACK, 619 * start to resend on end of deferring period to give 620 * last chance for data or ACK to create established socket. 621 */ 622 *resend = !inet_rsk(req)->acked || 623 req->num_timeout >= rskq_defer_accept - 1; 624 } 625 626 int inet_rtx_syn_ack(const struct sock *parent, struct request_sock *req) 627 { 628 int err = req->rsk_ops->rtx_syn_ack(parent, req); 629 630 if (!err) 631 req->num_retrans++; 632 return err; 633 } 634 EXPORT_SYMBOL(inet_rtx_syn_ack); 635 636 /* return true if req was found in the ehash table */ 637 static bool reqsk_queue_unlink(struct request_sock_queue *queue, 638 struct request_sock *req) 639 { 640 struct inet_hashinfo *hashinfo = req_to_sk(req)->sk_prot->h.hashinfo; 641 bool found = false; 642 643 if (sk_hashed(req_to_sk(req))) { 644 spinlock_t *lock = inet_ehash_lockp(hashinfo, req->rsk_hash); 645 646 spin_lock(lock); 647 found = __sk_nulls_del_node_init_rcu(req_to_sk(req)); 648 spin_unlock(lock); 649 } 650 if (timer_pending(&req->rsk_timer) && del_timer_sync(&req->rsk_timer)) 651 reqsk_put(req); 652 return found; 653 } 654 655 void inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req) 656 { 657 if (reqsk_queue_unlink(&inet_csk(sk)->icsk_accept_queue, req)) { 658 reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req); 659 reqsk_put(req); 660 } 661 } 662 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop); 663 664 void inet_csk_reqsk_queue_drop_and_put(struct sock *sk, struct request_sock *req) 665 { 666 inet_csk_reqsk_queue_drop(sk, req); 667 reqsk_put(req); 668 } 669 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop_and_put); 670 671 static void reqsk_timer_handler(struct timer_list *t) 672 { 673 struct request_sock *req = from_timer(req, t, rsk_timer); 674 struct sock *sk_listener = req->rsk_listener; 675 struct net *net = sock_net(sk_listener); 676 struct inet_connection_sock *icsk = inet_csk(sk_listener); 677 struct request_sock_queue *queue = &icsk->icsk_accept_queue; 678 int qlen, expire = 0, resend = 0; 679 int max_retries, thresh; 680 u8 defer_accept; 681 682 if (inet_sk_state_load(sk_listener) != TCP_LISTEN) 683 goto drop; 684 685 max_retries = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_synack_retries; 686 thresh = max_retries; 687 /* Normally all the openreqs are young and become mature 688 * (i.e. converted to established socket) for first timeout. 689 * If synack was not acknowledged for 1 second, it means 690 * one of the following things: synack was lost, ack was lost, 691 * rtt is high or nobody planned to ack (i.e. synflood). 692 * When server is a bit loaded, queue is populated with old 693 * open requests, reducing effective size of queue. 694 * When server is well loaded, queue size reduces to zero 695 * after several minutes of work. It is not synflood, 696 * it is normal operation. The solution is pruning 697 * too old entries overriding normal timeout, when 698 * situation becomes dangerous. 699 * 700 * Essentially, we reserve half of room for young 701 * embrions; and abort old ones without pity, if old 702 * ones are about to clog our table. 703 */ 704 qlen = reqsk_queue_len(queue); 705 if ((qlen << 1) > max(8U, sk_listener->sk_max_ack_backlog)) { 706 int young = reqsk_queue_len_young(queue) << 1; 707 708 while (thresh > 2) { 709 if (qlen < young) 710 break; 711 thresh--; 712 young <<= 1; 713 } 714 } 715 defer_accept = READ_ONCE(queue->rskq_defer_accept); 716 if (defer_accept) 717 max_retries = defer_accept; 718 syn_ack_recalc(req, thresh, max_retries, defer_accept, 719 &expire, &resend); 720 req->rsk_ops->syn_ack_timeout(req); 721 if (!expire && 722 (!resend || 723 !inet_rtx_syn_ack(sk_listener, req) || 724 inet_rsk(req)->acked)) { 725 unsigned long timeo; 726 727 if (req->num_timeout++ == 0) 728 atomic_dec(&queue->young); 729 timeo = min(TCP_TIMEOUT_INIT << req->num_timeout, TCP_RTO_MAX); 730 mod_timer(&req->rsk_timer, jiffies + timeo); 731 return; 732 } 733 drop: 734 inet_csk_reqsk_queue_drop_and_put(sk_listener, req); 735 } 736 737 static void reqsk_queue_hash_req(struct request_sock *req, 738 unsigned long timeout) 739 { 740 req->num_retrans = 0; 741 req->num_timeout = 0; 742 req->sk = NULL; 743 744 timer_setup(&req->rsk_timer, reqsk_timer_handler, TIMER_PINNED); 745 mod_timer(&req->rsk_timer, jiffies + timeout); 746 747 inet_ehash_insert(req_to_sk(req), NULL); 748 /* before letting lookups find us, make sure all req fields 749 * are committed to memory and refcnt initialized. 750 */ 751 smp_wmb(); 752 refcount_set(&req->rsk_refcnt, 2 + 1); 753 } 754 755 void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req, 756 unsigned long timeout) 757 { 758 reqsk_queue_hash_req(req, timeout); 759 inet_csk_reqsk_queue_added(sk); 760 } 761 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add); 762 763 /** 764 * inet_csk_clone_lock - clone an inet socket, and lock its clone 765 * @sk: the socket to clone 766 * @req: request_sock 767 * @priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc) 768 * 769 * Caller must unlock socket even in error path (bh_unlock_sock(newsk)) 770 */ 771 struct sock *inet_csk_clone_lock(const struct sock *sk, 772 const struct request_sock *req, 773 const gfp_t priority) 774 { 775 struct sock *newsk = sk_clone_lock(sk, priority); 776 777 if (newsk) { 778 struct inet_connection_sock *newicsk = inet_csk(newsk); 779 780 inet_sk_set_state(newsk, TCP_SYN_RECV); 781 newicsk->icsk_bind_hash = NULL; 782 783 inet_sk(newsk)->inet_dport = inet_rsk(req)->ir_rmt_port; 784 inet_sk(newsk)->inet_num = inet_rsk(req)->ir_num; 785 inet_sk(newsk)->inet_sport = htons(inet_rsk(req)->ir_num); 786 787 /* listeners have SOCK_RCU_FREE, not the children */ 788 sock_reset_flag(newsk, SOCK_RCU_FREE); 789 790 inet_sk(newsk)->mc_list = NULL; 791 792 newsk->sk_mark = inet_rsk(req)->ir_mark; 793 atomic64_set(&newsk->sk_cookie, 794 atomic64_read(&inet_rsk(req)->ir_cookie)); 795 796 newicsk->icsk_retransmits = 0; 797 newicsk->icsk_backoff = 0; 798 newicsk->icsk_probes_out = 0; 799 800 /* Deinitialize accept_queue to trap illegal accesses. */ 801 memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue)); 802 803 security_inet_csk_clone(newsk, req); 804 } 805 return newsk; 806 } 807 EXPORT_SYMBOL_GPL(inet_csk_clone_lock); 808 809 /* 810 * At this point, there should be no process reference to this 811 * socket, and thus no user references at all. Therefore we 812 * can assume the socket waitqueue is inactive and nobody will 813 * try to jump onto it. 814 */ 815 void inet_csk_destroy_sock(struct sock *sk) 816 { 817 WARN_ON(sk->sk_state != TCP_CLOSE); 818 WARN_ON(!sock_flag(sk, SOCK_DEAD)); 819 820 /* It cannot be in hash table! */ 821 WARN_ON(!sk_unhashed(sk)); 822 823 /* If it has not 0 inet_sk(sk)->inet_num, it must be bound */ 824 WARN_ON(inet_sk(sk)->inet_num && !inet_csk(sk)->icsk_bind_hash); 825 826 sk->sk_prot->destroy(sk); 827 828 sk_stream_kill_queues(sk); 829 830 xfrm_sk_free_policy(sk); 831 832 sk_refcnt_debug_release(sk); 833 834 percpu_counter_dec(sk->sk_prot->orphan_count); 835 836 sock_put(sk); 837 } 838 EXPORT_SYMBOL(inet_csk_destroy_sock); 839 840 /* This function allows to force a closure of a socket after the call to 841 * tcp/dccp_create_openreq_child(). 842 */ 843 void inet_csk_prepare_forced_close(struct sock *sk) 844 __releases(&sk->sk_lock.slock) 845 { 846 /* sk_clone_lock locked the socket and set refcnt to 2 */ 847 bh_unlock_sock(sk); 848 sock_put(sk); 849 850 /* The below has to be done to allow calling inet_csk_destroy_sock */ 851 sock_set_flag(sk, SOCK_DEAD); 852 percpu_counter_inc(sk->sk_prot->orphan_count); 853 inet_sk(sk)->inet_num = 0; 854 } 855 EXPORT_SYMBOL(inet_csk_prepare_forced_close); 856 857 int inet_csk_listen_start(struct sock *sk, int backlog) 858 { 859 struct inet_connection_sock *icsk = inet_csk(sk); 860 struct inet_sock *inet = inet_sk(sk); 861 int err = -EADDRINUSE; 862 863 reqsk_queue_alloc(&icsk->icsk_accept_queue); 864 865 sk->sk_max_ack_backlog = backlog; 866 sk->sk_ack_backlog = 0; 867 inet_csk_delack_init(sk); 868 869 /* There is race window here: we announce ourselves listening, 870 * but this transition is still not validated by get_port(). 871 * It is OK, because this socket enters to hash table only 872 * after validation is complete. 873 */ 874 inet_sk_state_store(sk, TCP_LISTEN); 875 if (!sk->sk_prot->get_port(sk, inet->inet_num)) { 876 inet->inet_sport = htons(inet->inet_num); 877 878 sk_dst_reset(sk); 879 err = sk->sk_prot->hash(sk); 880 881 if (likely(!err)) 882 return 0; 883 } 884 885 inet_sk_set_state(sk, TCP_CLOSE); 886 return err; 887 } 888 EXPORT_SYMBOL_GPL(inet_csk_listen_start); 889 890 static void inet_child_forget(struct sock *sk, struct request_sock *req, 891 struct sock *child) 892 { 893 sk->sk_prot->disconnect(child, O_NONBLOCK); 894 895 sock_orphan(child); 896 897 percpu_counter_inc(sk->sk_prot->orphan_count); 898 899 if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(req)->tfo_listener) { 900 BUG_ON(tcp_sk(child)->fastopen_rsk != req); 901 BUG_ON(sk != req->rsk_listener); 902 903 /* Paranoid, to prevent race condition if 904 * an inbound pkt destined for child is 905 * blocked by sock lock in tcp_v4_rcv(). 906 * Also to satisfy an assertion in 907 * tcp_v4_destroy_sock(). 908 */ 909 tcp_sk(child)->fastopen_rsk = NULL; 910 } 911 inet_csk_destroy_sock(child); 912 } 913 914 struct sock *inet_csk_reqsk_queue_add(struct sock *sk, 915 struct request_sock *req, 916 struct sock *child) 917 { 918 struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue; 919 920 spin_lock(&queue->rskq_lock); 921 if (unlikely(sk->sk_state != TCP_LISTEN)) { 922 inet_child_forget(sk, req, child); 923 child = NULL; 924 } else { 925 req->sk = child; 926 req->dl_next = NULL; 927 if (queue->rskq_accept_head == NULL) 928 queue->rskq_accept_head = req; 929 else 930 queue->rskq_accept_tail->dl_next = req; 931 queue->rskq_accept_tail = req; 932 sk_acceptq_added(sk); 933 } 934 spin_unlock(&queue->rskq_lock); 935 return child; 936 } 937 EXPORT_SYMBOL(inet_csk_reqsk_queue_add); 938 939 struct sock *inet_csk_complete_hashdance(struct sock *sk, struct sock *child, 940 struct request_sock *req, bool own_req) 941 { 942 if (own_req) { 943 inet_csk_reqsk_queue_drop(sk, req); 944 reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req); 945 if (inet_csk_reqsk_queue_add(sk, req, child)) 946 return child; 947 } 948 /* Too bad, another child took ownership of the request, undo. */ 949 bh_unlock_sock(child); 950 sock_put(child); 951 return NULL; 952 } 953 EXPORT_SYMBOL(inet_csk_complete_hashdance); 954 955 /* 956 * This routine closes sockets which have been at least partially 957 * opened, but not yet accepted. 958 */ 959 void inet_csk_listen_stop(struct sock *sk) 960 { 961 struct inet_connection_sock *icsk = inet_csk(sk); 962 struct request_sock_queue *queue = &icsk->icsk_accept_queue; 963 struct request_sock *next, *req; 964 965 /* Following specs, it would be better either to send FIN 966 * (and enter FIN-WAIT-1, it is normal close) 967 * or to send active reset (abort). 968 * Certainly, it is pretty dangerous while synflood, but it is 969 * bad justification for our negligence 8) 970 * To be honest, we are not able to make either 971 * of the variants now. --ANK 972 */ 973 while ((req = reqsk_queue_remove(queue, sk)) != NULL) { 974 struct sock *child = req->sk; 975 976 local_bh_disable(); 977 bh_lock_sock(child); 978 WARN_ON(sock_owned_by_user(child)); 979 sock_hold(child); 980 981 inet_child_forget(sk, req, child); 982 reqsk_put(req); 983 bh_unlock_sock(child); 984 local_bh_enable(); 985 sock_put(child); 986 987 cond_resched(); 988 } 989 if (queue->fastopenq.rskq_rst_head) { 990 /* Free all the reqs queued in rskq_rst_head. */ 991 spin_lock_bh(&queue->fastopenq.lock); 992 req = queue->fastopenq.rskq_rst_head; 993 queue->fastopenq.rskq_rst_head = NULL; 994 spin_unlock_bh(&queue->fastopenq.lock); 995 while (req != NULL) { 996 next = req->dl_next; 997 reqsk_put(req); 998 req = next; 999 } 1000 } 1001 WARN_ON_ONCE(sk->sk_ack_backlog); 1002 } 1003 EXPORT_SYMBOL_GPL(inet_csk_listen_stop); 1004 1005 void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr) 1006 { 1007 struct sockaddr_in *sin = (struct sockaddr_in *)uaddr; 1008 const struct inet_sock *inet = inet_sk(sk); 1009 1010 sin->sin_family = AF_INET; 1011 sin->sin_addr.s_addr = inet->inet_daddr; 1012 sin->sin_port = inet->inet_dport; 1013 } 1014 EXPORT_SYMBOL_GPL(inet_csk_addr2sockaddr); 1015 1016 #ifdef CONFIG_COMPAT 1017 int inet_csk_compat_getsockopt(struct sock *sk, int level, int optname, 1018 char __user *optval, int __user *optlen) 1019 { 1020 const struct inet_connection_sock *icsk = inet_csk(sk); 1021 1022 if (icsk->icsk_af_ops->compat_getsockopt) 1023 return icsk->icsk_af_ops->compat_getsockopt(sk, level, optname, 1024 optval, optlen); 1025 return icsk->icsk_af_ops->getsockopt(sk, level, optname, 1026 optval, optlen); 1027 } 1028 EXPORT_SYMBOL_GPL(inet_csk_compat_getsockopt); 1029 1030 int inet_csk_compat_setsockopt(struct sock *sk, int level, int optname, 1031 char __user *optval, unsigned int optlen) 1032 { 1033 const struct inet_connection_sock *icsk = inet_csk(sk); 1034 1035 if (icsk->icsk_af_ops->compat_setsockopt) 1036 return icsk->icsk_af_ops->compat_setsockopt(sk, level, optname, 1037 optval, optlen); 1038 return icsk->icsk_af_ops->setsockopt(sk, level, optname, 1039 optval, optlen); 1040 } 1041 EXPORT_SYMBOL_GPL(inet_csk_compat_setsockopt); 1042 #endif 1043 1044 static struct dst_entry *inet_csk_rebuild_route(struct sock *sk, struct flowi *fl) 1045 { 1046 const struct inet_sock *inet = inet_sk(sk); 1047 const struct ip_options_rcu *inet_opt; 1048 __be32 daddr = inet->inet_daddr; 1049 struct flowi4 *fl4; 1050 struct rtable *rt; 1051 1052 rcu_read_lock(); 1053 inet_opt = rcu_dereference(inet->inet_opt); 1054 if (inet_opt && inet_opt->opt.srr) 1055 daddr = inet_opt->opt.faddr; 1056 fl4 = &fl->u.ip4; 1057 rt = ip_route_output_ports(sock_net(sk), fl4, sk, daddr, 1058 inet->inet_saddr, inet->inet_dport, 1059 inet->inet_sport, sk->sk_protocol, 1060 RT_CONN_FLAGS(sk), sk->sk_bound_dev_if); 1061 if (IS_ERR(rt)) 1062 rt = NULL; 1063 if (rt) 1064 sk_setup_caps(sk, &rt->dst); 1065 rcu_read_unlock(); 1066 1067 return &rt->dst; 1068 } 1069 1070 struct dst_entry *inet_csk_update_pmtu(struct sock *sk, u32 mtu) 1071 { 1072 struct dst_entry *dst = __sk_dst_check(sk, 0); 1073 struct inet_sock *inet = inet_sk(sk); 1074 1075 if (!dst) { 1076 dst = inet_csk_rebuild_route(sk, &inet->cork.fl); 1077 if (!dst) 1078 goto out; 1079 } 1080 dst->ops->update_pmtu(dst, sk, NULL, mtu); 1081 1082 dst = __sk_dst_check(sk, 0); 1083 if (!dst) 1084 dst = inet_csk_rebuild_route(sk, &inet->cork.fl); 1085 out: 1086 return dst; 1087 } 1088 EXPORT_SYMBOL_GPL(inet_csk_update_pmtu); 1089