1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * INET An implementation of the TCP/IP protocol suite for the LINUX 4 * operating system. INET is implemented using the BSD Socket 5 * interface as the means of communication with the user level. 6 * 7 * Support for INET connection oriented protocols. 8 * 9 * Authors: See the TCP sources 10 */ 11 12 #include <linux/module.h> 13 #include <linux/jhash.h> 14 15 #include <net/inet_connection_sock.h> 16 #include <net/inet_hashtables.h> 17 #include <net/inet_timewait_sock.h> 18 #include <net/ip.h> 19 #include <net/route.h> 20 #include <net/tcp_states.h> 21 #include <net/xfrm.h> 22 #include <net/tcp.h> 23 #include <net/sock_reuseport.h> 24 #include <net/addrconf.h> 25 26 #if IS_ENABLED(CONFIG_IPV6) 27 /* match_sk*_wildcard == true: IPV6_ADDR_ANY equals to any IPv6 addresses 28 * if IPv6 only, and any IPv4 addresses 29 * if not IPv6 only 30 * match_sk*_wildcard == false: addresses must be exactly the same, i.e. 31 * IPV6_ADDR_ANY only equals to IPV6_ADDR_ANY, 32 * and 0.0.0.0 equals to 0.0.0.0 only 33 */ 34 static bool ipv6_rcv_saddr_equal(const struct in6_addr *sk1_rcv_saddr6, 35 const struct in6_addr *sk2_rcv_saddr6, 36 __be32 sk1_rcv_saddr, __be32 sk2_rcv_saddr, 37 bool sk1_ipv6only, bool sk2_ipv6only, 38 bool match_sk1_wildcard, 39 bool match_sk2_wildcard) 40 { 41 int addr_type = ipv6_addr_type(sk1_rcv_saddr6); 42 int addr_type2 = sk2_rcv_saddr6 ? ipv6_addr_type(sk2_rcv_saddr6) : IPV6_ADDR_MAPPED; 43 44 /* if both are mapped, treat as IPv4 */ 45 if (addr_type == IPV6_ADDR_MAPPED && addr_type2 == IPV6_ADDR_MAPPED) { 46 if (!sk2_ipv6only) { 47 if (sk1_rcv_saddr == sk2_rcv_saddr) 48 return true; 49 return (match_sk1_wildcard && !sk1_rcv_saddr) || 50 (match_sk2_wildcard && !sk2_rcv_saddr); 51 } 52 return false; 53 } 54 55 if (addr_type == IPV6_ADDR_ANY && addr_type2 == IPV6_ADDR_ANY) 56 return true; 57 58 if (addr_type2 == IPV6_ADDR_ANY && match_sk2_wildcard && 59 !(sk2_ipv6only && addr_type == IPV6_ADDR_MAPPED)) 60 return true; 61 62 if (addr_type == IPV6_ADDR_ANY && match_sk1_wildcard && 63 !(sk1_ipv6only && addr_type2 == IPV6_ADDR_MAPPED)) 64 return true; 65 66 if (sk2_rcv_saddr6 && 67 ipv6_addr_equal(sk1_rcv_saddr6, sk2_rcv_saddr6)) 68 return true; 69 70 return false; 71 } 72 #endif 73 74 /* match_sk*_wildcard == true: 0.0.0.0 equals to any IPv4 addresses 75 * match_sk*_wildcard == false: addresses must be exactly the same, i.e. 76 * 0.0.0.0 only equals to 0.0.0.0 77 */ 78 static bool ipv4_rcv_saddr_equal(__be32 sk1_rcv_saddr, __be32 sk2_rcv_saddr, 79 bool sk2_ipv6only, bool match_sk1_wildcard, 80 bool match_sk2_wildcard) 81 { 82 if (!sk2_ipv6only) { 83 if (sk1_rcv_saddr == sk2_rcv_saddr) 84 return true; 85 return (match_sk1_wildcard && !sk1_rcv_saddr) || 86 (match_sk2_wildcard && !sk2_rcv_saddr); 87 } 88 return false; 89 } 90 91 bool inet_rcv_saddr_equal(const struct sock *sk, const struct sock *sk2, 92 bool match_wildcard) 93 { 94 #if IS_ENABLED(CONFIG_IPV6) 95 if (sk->sk_family == AF_INET6) 96 return ipv6_rcv_saddr_equal(&sk->sk_v6_rcv_saddr, 97 inet6_rcv_saddr(sk2), 98 sk->sk_rcv_saddr, 99 sk2->sk_rcv_saddr, 100 ipv6_only_sock(sk), 101 ipv6_only_sock(sk2), 102 match_wildcard, 103 match_wildcard); 104 #endif 105 return ipv4_rcv_saddr_equal(sk->sk_rcv_saddr, sk2->sk_rcv_saddr, 106 ipv6_only_sock(sk2), match_wildcard, 107 match_wildcard); 108 } 109 EXPORT_SYMBOL(inet_rcv_saddr_equal); 110 111 bool inet_rcv_saddr_any(const struct sock *sk) 112 { 113 #if IS_ENABLED(CONFIG_IPV6) 114 if (sk->sk_family == AF_INET6) 115 return ipv6_addr_any(&sk->sk_v6_rcv_saddr); 116 #endif 117 return !sk->sk_rcv_saddr; 118 } 119 120 void inet_get_local_port_range(struct net *net, int *low, int *high) 121 { 122 unsigned int seq; 123 124 do { 125 seq = read_seqbegin(&net->ipv4.ip_local_ports.lock); 126 127 *low = net->ipv4.ip_local_ports.range[0]; 128 *high = net->ipv4.ip_local_ports.range[1]; 129 } while (read_seqretry(&net->ipv4.ip_local_ports.lock, seq)); 130 } 131 EXPORT_SYMBOL(inet_get_local_port_range); 132 133 static int inet_csk_bind_conflict(const struct sock *sk, 134 const struct inet_bind_bucket *tb, 135 bool relax, bool reuseport_ok) 136 { 137 struct sock *sk2; 138 bool reuse = sk->sk_reuse; 139 bool reuseport = !!sk->sk_reuseport; 140 kuid_t uid = sock_i_uid((struct sock *)sk); 141 142 /* 143 * Unlike other sk lookup places we do not check 144 * for sk_net here, since _all_ the socks listed 145 * in tb->owners list belong to the same net - the 146 * one this bucket belongs to. 147 */ 148 149 sk_for_each_bound(sk2, &tb->owners) { 150 if (sk != sk2 && 151 (!sk->sk_bound_dev_if || 152 !sk2->sk_bound_dev_if || 153 sk->sk_bound_dev_if == sk2->sk_bound_dev_if)) { 154 if (reuse && sk2->sk_reuse && 155 sk2->sk_state != TCP_LISTEN) { 156 if ((!relax || 157 (!reuseport_ok && 158 reuseport && sk2->sk_reuseport && 159 !rcu_access_pointer(sk->sk_reuseport_cb) && 160 (sk2->sk_state == TCP_TIME_WAIT || 161 uid_eq(uid, sock_i_uid(sk2))))) && 162 inet_rcv_saddr_equal(sk, sk2, true)) 163 break; 164 } else if (!reuseport_ok || 165 !reuseport || !sk2->sk_reuseport || 166 rcu_access_pointer(sk->sk_reuseport_cb) || 167 (sk2->sk_state != TCP_TIME_WAIT && 168 !uid_eq(uid, sock_i_uid(sk2)))) { 169 if (inet_rcv_saddr_equal(sk, sk2, true)) 170 break; 171 } 172 } 173 } 174 return sk2 != NULL; 175 } 176 177 /* 178 * Find an open port number for the socket. Returns with the 179 * inet_bind_hashbucket lock held. 180 */ 181 static struct inet_bind_hashbucket * 182 inet_csk_find_open_port(struct sock *sk, struct inet_bind_bucket **tb_ret, int *port_ret) 183 { 184 struct inet_hashinfo *hinfo = sk->sk_prot->h.hashinfo; 185 int port = 0; 186 struct inet_bind_hashbucket *head; 187 struct net *net = sock_net(sk); 188 bool relax = false; 189 int i, low, high, attempt_half; 190 struct inet_bind_bucket *tb; 191 u32 remaining, offset; 192 int l3mdev; 193 194 l3mdev = inet_sk_bound_l3mdev(sk); 195 ports_exhausted: 196 attempt_half = (sk->sk_reuse == SK_CAN_REUSE) ? 1 : 0; 197 other_half_scan: 198 inet_get_local_port_range(net, &low, &high); 199 high++; /* [32768, 60999] -> [32768, 61000[ */ 200 if (high - low < 4) 201 attempt_half = 0; 202 if (attempt_half) { 203 int half = low + (((high - low) >> 2) << 1); 204 205 if (attempt_half == 1) 206 high = half; 207 else 208 low = half; 209 } 210 remaining = high - low; 211 if (likely(remaining > 1)) 212 remaining &= ~1U; 213 214 offset = prandom_u32() % remaining; 215 /* __inet_hash_connect() favors ports having @low parity 216 * We do the opposite to not pollute connect() users. 217 */ 218 offset |= 1U; 219 220 other_parity_scan: 221 port = low + offset; 222 for (i = 0; i < remaining; i += 2, port += 2) { 223 if (unlikely(port >= high)) 224 port -= remaining; 225 if (inet_is_local_reserved_port(net, port)) 226 continue; 227 head = &hinfo->bhash[inet_bhashfn(net, port, 228 hinfo->bhash_size)]; 229 spin_lock_bh(&head->lock); 230 inet_bind_bucket_for_each(tb, &head->chain) 231 if (net_eq(ib_net(tb), net) && tb->l3mdev == l3mdev && 232 tb->port == port) { 233 if (!inet_csk_bind_conflict(sk, tb, relax, false)) 234 goto success; 235 goto next_port; 236 } 237 tb = NULL; 238 goto success; 239 next_port: 240 spin_unlock_bh(&head->lock); 241 cond_resched(); 242 } 243 244 offset--; 245 if (!(offset & 1)) 246 goto other_parity_scan; 247 248 if (attempt_half == 1) { 249 /* OK we now try the upper half of the range */ 250 attempt_half = 2; 251 goto other_half_scan; 252 } 253 254 if (net->ipv4.sysctl_ip_autobind_reuse && !relax) { 255 /* We still have a chance to connect to different destinations */ 256 relax = true; 257 goto ports_exhausted; 258 } 259 return NULL; 260 success: 261 *port_ret = port; 262 *tb_ret = tb; 263 return head; 264 } 265 266 static inline int sk_reuseport_match(struct inet_bind_bucket *tb, 267 struct sock *sk) 268 { 269 kuid_t uid = sock_i_uid(sk); 270 271 if (tb->fastreuseport <= 0) 272 return 0; 273 if (!sk->sk_reuseport) 274 return 0; 275 if (rcu_access_pointer(sk->sk_reuseport_cb)) 276 return 0; 277 if (!uid_eq(tb->fastuid, uid)) 278 return 0; 279 /* We only need to check the rcv_saddr if this tb was once marked 280 * without fastreuseport and then was reset, as we can only know that 281 * the fast_*rcv_saddr doesn't have any conflicts with the socks on the 282 * owners list. 283 */ 284 if (tb->fastreuseport == FASTREUSEPORT_ANY) 285 return 1; 286 #if IS_ENABLED(CONFIG_IPV6) 287 if (tb->fast_sk_family == AF_INET6) 288 return ipv6_rcv_saddr_equal(&tb->fast_v6_rcv_saddr, 289 inet6_rcv_saddr(sk), 290 tb->fast_rcv_saddr, 291 sk->sk_rcv_saddr, 292 tb->fast_ipv6_only, 293 ipv6_only_sock(sk), true, false); 294 #endif 295 return ipv4_rcv_saddr_equal(tb->fast_rcv_saddr, sk->sk_rcv_saddr, 296 ipv6_only_sock(sk), true, false); 297 } 298 299 void inet_csk_update_fastreuse(struct inet_bind_bucket *tb, 300 struct sock *sk) 301 { 302 kuid_t uid = sock_i_uid(sk); 303 bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN; 304 305 if (hlist_empty(&tb->owners)) { 306 tb->fastreuse = reuse; 307 if (sk->sk_reuseport) { 308 tb->fastreuseport = FASTREUSEPORT_ANY; 309 tb->fastuid = uid; 310 tb->fast_rcv_saddr = sk->sk_rcv_saddr; 311 tb->fast_ipv6_only = ipv6_only_sock(sk); 312 tb->fast_sk_family = sk->sk_family; 313 #if IS_ENABLED(CONFIG_IPV6) 314 tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr; 315 #endif 316 } else { 317 tb->fastreuseport = 0; 318 } 319 } else { 320 if (!reuse) 321 tb->fastreuse = 0; 322 if (sk->sk_reuseport) { 323 /* We didn't match or we don't have fastreuseport set on 324 * the tb, but we have sk_reuseport set on this socket 325 * and we know that there are no bind conflicts with 326 * this socket in this tb, so reset our tb's reuseport 327 * settings so that any subsequent sockets that match 328 * our current socket will be put on the fast path. 329 * 330 * If we reset we need to set FASTREUSEPORT_STRICT so we 331 * do extra checking for all subsequent sk_reuseport 332 * socks. 333 */ 334 if (!sk_reuseport_match(tb, sk)) { 335 tb->fastreuseport = FASTREUSEPORT_STRICT; 336 tb->fastuid = uid; 337 tb->fast_rcv_saddr = sk->sk_rcv_saddr; 338 tb->fast_ipv6_only = ipv6_only_sock(sk); 339 tb->fast_sk_family = sk->sk_family; 340 #if IS_ENABLED(CONFIG_IPV6) 341 tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr; 342 #endif 343 } 344 } else { 345 tb->fastreuseport = 0; 346 } 347 } 348 } 349 350 /* Obtain a reference to a local port for the given sock, 351 * if snum is zero it means select any available local port. 352 * We try to allocate an odd port (and leave even ports for connect()) 353 */ 354 int inet_csk_get_port(struct sock *sk, unsigned short snum) 355 { 356 bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN; 357 struct inet_hashinfo *hinfo = sk->sk_prot->h.hashinfo; 358 int ret = 1, port = snum; 359 struct inet_bind_hashbucket *head; 360 struct net *net = sock_net(sk); 361 struct inet_bind_bucket *tb = NULL; 362 int l3mdev; 363 364 l3mdev = inet_sk_bound_l3mdev(sk); 365 366 if (!port) { 367 head = inet_csk_find_open_port(sk, &tb, &port); 368 if (!head) 369 return ret; 370 if (!tb) 371 goto tb_not_found; 372 goto success; 373 } 374 head = &hinfo->bhash[inet_bhashfn(net, port, 375 hinfo->bhash_size)]; 376 spin_lock_bh(&head->lock); 377 inet_bind_bucket_for_each(tb, &head->chain) 378 if (net_eq(ib_net(tb), net) && tb->l3mdev == l3mdev && 379 tb->port == port) 380 goto tb_found; 381 tb_not_found: 382 tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep, 383 net, head, port, l3mdev); 384 if (!tb) 385 goto fail_unlock; 386 tb_found: 387 if (!hlist_empty(&tb->owners)) { 388 if (sk->sk_reuse == SK_FORCE_REUSE) 389 goto success; 390 391 if ((tb->fastreuse > 0 && reuse) || 392 sk_reuseport_match(tb, sk)) 393 goto success; 394 if (inet_csk_bind_conflict(sk, tb, true, true)) 395 goto fail_unlock; 396 } 397 success: 398 inet_csk_update_fastreuse(tb, sk); 399 400 if (!inet_csk(sk)->icsk_bind_hash) 401 inet_bind_hash(sk, tb, port); 402 WARN_ON(inet_csk(sk)->icsk_bind_hash != tb); 403 ret = 0; 404 405 fail_unlock: 406 spin_unlock_bh(&head->lock); 407 return ret; 408 } 409 EXPORT_SYMBOL_GPL(inet_csk_get_port); 410 411 /* 412 * Wait for an incoming connection, avoid race conditions. This must be called 413 * with the socket locked. 414 */ 415 static int inet_csk_wait_for_connect(struct sock *sk, long timeo) 416 { 417 struct inet_connection_sock *icsk = inet_csk(sk); 418 DEFINE_WAIT(wait); 419 int err; 420 421 /* 422 * True wake-one mechanism for incoming connections: only 423 * one process gets woken up, not the 'whole herd'. 424 * Since we do not 'race & poll' for established sockets 425 * anymore, the common case will execute the loop only once. 426 * 427 * Subtle issue: "add_wait_queue_exclusive()" will be added 428 * after any current non-exclusive waiters, and we know that 429 * it will always _stay_ after any new non-exclusive waiters 430 * because all non-exclusive waiters are added at the 431 * beginning of the wait-queue. As such, it's ok to "drop" 432 * our exclusiveness temporarily when we get woken up without 433 * having to remove and re-insert us on the wait queue. 434 */ 435 for (;;) { 436 prepare_to_wait_exclusive(sk_sleep(sk), &wait, 437 TASK_INTERRUPTIBLE); 438 release_sock(sk); 439 if (reqsk_queue_empty(&icsk->icsk_accept_queue)) 440 timeo = schedule_timeout(timeo); 441 sched_annotate_sleep(); 442 lock_sock(sk); 443 err = 0; 444 if (!reqsk_queue_empty(&icsk->icsk_accept_queue)) 445 break; 446 err = -EINVAL; 447 if (sk->sk_state != TCP_LISTEN) 448 break; 449 err = sock_intr_errno(timeo); 450 if (signal_pending(current)) 451 break; 452 err = -EAGAIN; 453 if (!timeo) 454 break; 455 } 456 finish_wait(sk_sleep(sk), &wait); 457 return err; 458 } 459 460 /* 461 * This will accept the next outstanding connection. 462 */ 463 struct sock *inet_csk_accept(struct sock *sk, int flags, int *err, bool kern) 464 { 465 struct inet_connection_sock *icsk = inet_csk(sk); 466 struct request_sock_queue *queue = &icsk->icsk_accept_queue; 467 struct request_sock *req; 468 struct sock *newsk; 469 int error; 470 471 lock_sock(sk); 472 473 /* We need to make sure that this socket is listening, 474 * and that it has something pending. 475 */ 476 error = -EINVAL; 477 if (sk->sk_state != TCP_LISTEN) 478 goto out_err; 479 480 /* Find already established connection */ 481 if (reqsk_queue_empty(queue)) { 482 long timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK); 483 484 /* If this is a non blocking socket don't sleep */ 485 error = -EAGAIN; 486 if (!timeo) 487 goto out_err; 488 489 error = inet_csk_wait_for_connect(sk, timeo); 490 if (error) 491 goto out_err; 492 } 493 req = reqsk_queue_remove(queue, sk); 494 newsk = req->sk; 495 496 if (sk->sk_protocol == IPPROTO_TCP && 497 tcp_rsk(req)->tfo_listener) { 498 spin_lock_bh(&queue->fastopenq.lock); 499 if (tcp_rsk(req)->tfo_listener) { 500 /* We are still waiting for the final ACK from 3WHS 501 * so can't free req now. Instead, we set req->sk to 502 * NULL to signify that the child socket is taken 503 * so reqsk_fastopen_remove() will free the req 504 * when 3WHS finishes (or is aborted). 505 */ 506 req->sk = NULL; 507 req = NULL; 508 } 509 spin_unlock_bh(&queue->fastopenq.lock); 510 } 511 512 out: 513 release_sock(sk); 514 if (newsk && mem_cgroup_sockets_enabled) { 515 int amt; 516 517 /* atomically get the memory usage, set and charge the 518 * newsk->sk_memcg. 519 */ 520 lock_sock(newsk); 521 522 /* The socket has not been accepted yet, no need to look at 523 * newsk->sk_wmem_queued. 524 */ 525 amt = sk_mem_pages(newsk->sk_forward_alloc + 526 atomic_read(&newsk->sk_rmem_alloc)); 527 mem_cgroup_sk_alloc(newsk); 528 if (newsk->sk_memcg && amt) 529 mem_cgroup_charge_skmem(newsk->sk_memcg, amt); 530 531 release_sock(newsk); 532 } 533 if (req) 534 reqsk_put(req); 535 return newsk; 536 out_err: 537 newsk = NULL; 538 req = NULL; 539 *err = error; 540 goto out; 541 } 542 EXPORT_SYMBOL(inet_csk_accept); 543 544 /* 545 * Using different timers for retransmit, delayed acks and probes 546 * We may wish use just one timer maintaining a list of expire jiffies 547 * to optimize. 548 */ 549 void inet_csk_init_xmit_timers(struct sock *sk, 550 void (*retransmit_handler)(struct timer_list *t), 551 void (*delack_handler)(struct timer_list *t), 552 void (*keepalive_handler)(struct timer_list *t)) 553 { 554 struct inet_connection_sock *icsk = inet_csk(sk); 555 556 timer_setup(&icsk->icsk_retransmit_timer, retransmit_handler, 0); 557 timer_setup(&icsk->icsk_delack_timer, delack_handler, 0); 558 timer_setup(&sk->sk_timer, keepalive_handler, 0); 559 icsk->icsk_pending = icsk->icsk_ack.pending = 0; 560 } 561 EXPORT_SYMBOL(inet_csk_init_xmit_timers); 562 563 void inet_csk_clear_xmit_timers(struct sock *sk) 564 { 565 struct inet_connection_sock *icsk = inet_csk(sk); 566 567 icsk->icsk_pending = icsk->icsk_ack.pending = 0; 568 569 sk_stop_timer(sk, &icsk->icsk_retransmit_timer); 570 sk_stop_timer(sk, &icsk->icsk_delack_timer); 571 sk_stop_timer(sk, &sk->sk_timer); 572 } 573 EXPORT_SYMBOL(inet_csk_clear_xmit_timers); 574 575 void inet_csk_delete_keepalive_timer(struct sock *sk) 576 { 577 sk_stop_timer(sk, &sk->sk_timer); 578 } 579 EXPORT_SYMBOL(inet_csk_delete_keepalive_timer); 580 581 void inet_csk_reset_keepalive_timer(struct sock *sk, unsigned long len) 582 { 583 sk_reset_timer(sk, &sk->sk_timer, jiffies + len); 584 } 585 EXPORT_SYMBOL(inet_csk_reset_keepalive_timer); 586 587 struct dst_entry *inet_csk_route_req(const struct sock *sk, 588 struct flowi4 *fl4, 589 const struct request_sock *req) 590 { 591 const struct inet_request_sock *ireq = inet_rsk(req); 592 struct net *net = read_pnet(&ireq->ireq_net); 593 struct ip_options_rcu *opt; 594 struct rtable *rt; 595 596 rcu_read_lock(); 597 opt = rcu_dereference(ireq->ireq_opt); 598 599 flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark, 600 RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE, 601 sk->sk_protocol, inet_sk_flowi_flags(sk), 602 (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr, 603 ireq->ir_loc_addr, ireq->ir_rmt_port, 604 htons(ireq->ir_num), sk->sk_uid); 605 security_req_classify_flow(req, flowi4_to_flowi_common(fl4)); 606 rt = ip_route_output_flow(net, fl4, sk); 607 if (IS_ERR(rt)) 608 goto no_route; 609 if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway) 610 goto route_err; 611 rcu_read_unlock(); 612 return &rt->dst; 613 614 route_err: 615 ip_rt_put(rt); 616 no_route: 617 rcu_read_unlock(); 618 __IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES); 619 return NULL; 620 } 621 EXPORT_SYMBOL_GPL(inet_csk_route_req); 622 623 struct dst_entry *inet_csk_route_child_sock(const struct sock *sk, 624 struct sock *newsk, 625 const struct request_sock *req) 626 { 627 const struct inet_request_sock *ireq = inet_rsk(req); 628 struct net *net = read_pnet(&ireq->ireq_net); 629 struct inet_sock *newinet = inet_sk(newsk); 630 struct ip_options_rcu *opt; 631 struct flowi4 *fl4; 632 struct rtable *rt; 633 634 opt = rcu_dereference(ireq->ireq_opt); 635 fl4 = &newinet->cork.fl.u.ip4; 636 637 flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark, 638 RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE, 639 sk->sk_protocol, inet_sk_flowi_flags(sk), 640 (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr, 641 ireq->ir_loc_addr, ireq->ir_rmt_port, 642 htons(ireq->ir_num), sk->sk_uid); 643 security_req_classify_flow(req, flowi4_to_flowi_common(fl4)); 644 rt = ip_route_output_flow(net, fl4, sk); 645 if (IS_ERR(rt)) 646 goto no_route; 647 if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway) 648 goto route_err; 649 return &rt->dst; 650 651 route_err: 652 ip_rt_put(rt); 653 no_route: 654 __IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES); 655 return NULL; 656 } 657 EXPORT_SYMBOL_GPL(inet_csk_route_child_sock); 658 659 /* Decide when to expire the request and when to resend SYN-ACK */ 660 static void syn_ack_recalc(struct request_sock *req, 661 const int max_syn_ack_retries, 662 const u8 rskq_defer_accept, 663 int *expire, int *resend) 664 { 665 if (!rskq_defer_accept) { 666 *expire = req->num_timeout >= max_syn_ack_retries; 667 *resend = 1; 668 return; 669 } 670 *expire = req->num_timeout >= max_syn_ack_retries && 671 (!inet_rsk(req)->acked || req->num_timeout >= rskq_defer_accept); 672 /* Do not resend while waiting for data after ACK, 673 * start to resend on end of deferring period to give 674 * last chance for data or ACK to create established socket. 675 */ 676 *resend = !inet_rsk(req)->acked || 677 req->num_timeout >= rskq_defer_accept - 1; 678 } 679 680 int inet_rtx_syn_ack(const struct sock *parent, struct request_sock *req) 681 { 682 int err = req->rsk_ops->rtx_syn_ack(parent, req); 683 684 if (!err) 685 req->num_retrans++; 686 return err; 687 } 688 EXPORT_SYMBOL(inet_rtx_syn_ack); 689 690 /* return true if req was found in the ehash table */ 691 static bool reqsk_queue_unlink(struct request_sock *req) 692 { 693 struct inet_hashinfo *hashinfo = req_to_sk(req)->sk_prot->h.hashinfo; 694 bool found = false; 695 696 if (sk_hashed(req_to_sk(req))) { 697 spinlock_t *lock = inet_ehash_lockp(hashinfo, req->rsk_hash); 698 699 spin_lock(lock); 700 found = __sk_nulls_del_node_init_rcu(req_to_sk(req)); 701 spin_unlock(lock); 702 } 703 if (timer_pending(&req->rsk_timer) && del_timer_sync(&req->rsk_timer)) 704 reqsk_put(req); 705 return found; 706 } 707 708 void inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req) 709 { 710 if (reqsk_queue_unlink(req)) { 711 reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req); 712 reqsk_put(req); 713 } 714 } 715 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop); 716 717 void inet_csk_reqsk_queue_drop_and_put(struct sock *sk, struct request_sock *req) 718 { 719 inet_csk_reqsk_queue_drop(sk, req); 720 reqsk_put(req); 721 } 722 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop_and_put); 723 724 static void reqsk_timer_handler(struct timer_list *t) 725 { 726 struct request_sock *req = from_timer(req, t, rsk_timer); 727 struct sock *sk_listener = req->rsk_listener; 728 struct net *net = sock_net(sk_listener); 729 struct inet_connection_sock *icsk = inet_csk(sk_listener); 730 struct request_sock_queue *queue = &icsk->icsk_accept_queue; 731 int max_syn_ack_retries, qlen, expire = 0, resend = 0; 732 733 if (inet_sk_state_load(sk_listener) != TCP_LISTEN) 734 goto drop; 735 736 max_syn_ack_retries = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_synack_retries; 737 /* Normally all the openreqs are young and become mature 738 * (i.e. converted to established socket) for first timeout. 739 * If synack was not acknowledged for 1 second, it means 740 * one of the following things: synack was lost, ack was lost, 741 * rtt is high or nobody planned to ack (i.e. synflood). 742 * When server is a bit loaded, queue is populated with old 743 * open requests, reducing effective size of queue. 744 * When server is well loaded, queue size reduces to zero 745 * after several minutes of work. It is not synflood, 746 * it is normal operation. The solution is pruning 747 * too old entries overriding normal timeout, when 748 * situation becomes dangerous. 749 * 750 * Essentially, we reserve half of room for young 751 * embrions; and abort old ones without pity, if old 752 * ones are about to clog our table. 753 */ 754 qlen = reqsk_queue_len(queue); 755 if ((qlen << 1) > max(8U, READ_ONCE(sk_listener->sk_max_ack_backlog))) { 756 int young = reqsk_queue_len_young(queue) << 1; 757 758 while (max_syn_ack_retries > 2) { 759 if (qlen < young) 760 break; 761 max_syn_ack_retries--; 762 young <<= 1; 763 } 764 } 765 syn_ack_recalc(req, max_syn_ack_retries, READ_ONCE(queue->rskq_defer_accept), 766 &expire, &resend); 767 req->rsk_ops->syn_ack_timeout(req); 768 if (!expire && 769 (!resend || 770 !inet_rtx_syn_ack(sk_listener, req) || 771 inet_rsk(req)->acked)) { 772 unsigned long timeo; 773 774 if (req->num_timeout++ == 0) 775 atomic_dec(&queue->young); 776 timeo = min(TCP_TIMEOUT_INIT << req->num_timeout, TCP_RTO_MAX); 777 mod_timer(&req->rsk_timer, jiffies + timeo); 778 return; 779 } 780 drop: 781 inet_csk_reqsk_queue_drop_and_put(sk_listener, req); 782 } 783 784 static void reqsk_queue_hash_req(struct request_sock *req, 785 unsigned long timeout) 786 { 787 timer_setup(&req->rsk_timer, reqsk_timer_handler, TIMER_PINNED); 788 mod_timer(&req->rsk_timer, jiffies + timeout); 789 790 inet_ehash_insert(req_to_sk(req), NULL, NULL); 791 /* before letting lookups find us, make sure all req fields 792 * are committed to memory and refcnt initialized. 793 */ 794 smp_wmb(); 795 refcount_set(&req->rsk_refcnt, 2 + 1); 796 } 797 798 void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req, 799 unsigned long timeout) 800 { 801 reqsk_queue_hash_req(req, timeout); 802 inet_csk_reqsk_queue_added(sk); 803 } 804 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add); 805 806 static void inet_clone_ulp(const struct request_sock *req, struct sock *newsk, 807 const gfp_t priority) 808 { 809 struct inet_connection_sock *icsk = inet_csk(newsk); 810 811 if (!icsk->icsk_ulp_ops) 812 return; 813 814 if (icsk->icsk_ulp_ops->clone) 815 icsk->icsk_ulp_ops->clone(req, newsk, priority); 816 } 817 818 /** 819 * inet_csk_clone_lock - clone an inet socket, and lock its clone 820 * @sk: the socket to clone 821 * @req: request_sock 822 * @priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc) 823 * 824 * Caller must unlock socket even in error path (bh_unlock_sock(newsk)) 825 */ 826 struct sock *inet_csk_clone_lock(const struct sock *sk, 827 const struct request_sock *req, 828 const gfp_t priority) 829 { 830 struct sock *newsk = sk_clone_lock(sk, priority); 831 832 if (newsk) { 833 struct inet_connection_sock *newicsk = inet_csk(newsk); 834 835 inet_sk_set_state(newsk, TCP_SYN_RECV); 836 newicsk->icsk_bind_hash = NULL; 837 838 inet_sk(newsk)->inet_dport = inet_rsk(req)->ir_rmt_port; 839 inet_sk(newsk)->inet_num = inet_rsk(req)->ir_num; 840 inet_sk(newsk)->inet_sport = htons(inet_rsk(req)->ir_num); 841 842 /* listeners have SOCK_RCU_FREE, not the children */ 843 sock_reset_flag(newsk, SOCK_RCU_FREE); 844 845 inet_sk(newsk)->mc_list = NULL; 846 847 newsk->sk_mark = inet_rsk(req)->ir_mark; 848 atomic64_set(&newsk->sk_cookie, 849 atomic64_read(&inet_rsk(req)->ir_cookie)); 850 851 newicsk->icsk_retransmits = 0; 852 newicsk->icsk_backoff = 0; 853 newicsk->icsk_probes_out = 0; 854 newicsk->icsk_probes_tstamp = 0; 855 856 /* Deinitialize accept_queue to trap illegal accesses. */ 857 memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue)); 858 859 inet_clone_ulp(req, newsk, priority); 860 861 security_inet_csk_clone(newsk, req); 862 } 863 return newsk; 864 } 865 EXPORT_SYMBOL_GPL(inet_csk_clone_lock); 866 867 /* 868 * At this point, there should be no process reference to this 869 * socket, and thus no user references at all. Therefore we 870 * can assume the socket waitqueue is inactive and nobody will 871 * try to jump onto it. 872 */ 873 void inet_csk_destroy_sock(struct sock *sk) 874 { 875 WARN_ON(sk->sk_state != TCP_CLOSE); 876 WARN_ON(!sock_flag(sk, SOCK_DEAD)); 877 878 /* It cannot be in hash table! */ 879 WARN_ON(!sk_unhashed(sk)); 880 881 /* If it has not 0 inet_sk(sk)->inet_num, it must be bound */ 882 WARN_ON(inet_sk(sk)->inet_num && !inet_csk(sk)->icsk_bind_hash); 883 884 sk->sk_prot->destroy(sk); 885 886 sk_stream_kill_queues(sk); 887 888 xfrm_sk_free_policy(sk); 889 890 sk_refcnt_debug_release(sk); 891 892 percpu_counter_dec(sk->sk_prot->orphan_count); 893 894 sock_put(sk); 895 } 896 EXPORT_SYMBOL(inet_csk_destroy_sock); 897 898 /* This function allows to force a closure of a socket after the call to 899 * tcp/dccp_create_openreq_child(). 900 */ 901 void inet_csk_prepare_forced_close(struct sock *sk) 902 __releases(&sk->sk_lock.slock) 903 { 904 /* sk_clone_lock locked the socket and set refcnt to 2 */ 905 bh_unlock_sock(sk); 906 sock_put(sk); 907 inet_csk_prepare_for_destroy_sock(sk); 908 inet_sk(sk)->inet_num = 0; 909 } 910 EXPORT_SYMBOL(inet_csk_prepare_forced_close); 911 912 int inet_csk_listen_start(struct sock *sk, int backlog) 913 { 914 struct inet_connection_sock *icsk = inet_csk(sk); 915 struct inet_sock *inet = inet_sk(sk); 916 int err = -EADDRINUSE; 917 918 reqsk_queue_alloc(&icsk->icsk_accept_queue); 919 920 sk->sk_ack_backlog = 0; 921 inet_csk_delack_init(sk); 922 923 /* There is race window here: we announce ourselves listening, 924 * but this transition is still not validated by get_port(). 925 * It is OK, because this socket enters to hash table only 926 * after validation is complete. 927 */ 928 inet_sk_state_store(sk, TCP_LISTEN); 929 if (!sk->sk_prot->get_port(sk, inet->inet_num)) { 930 inet->inet_sport = htons(inet->inet_num); 931 932 sk_dst_reset(sk); 933 err = sk->sk_prot->hash(sk); 934 935 if (likely(!err)) 936 return 0; 937 } 938 939 inet_sk_set_state(sk, TCP_CLOSE); 940 return err; 941 } 942 EXPORT_SYMBOL_GPL(inet_csk_listen_start); 943 944 static void inet_child_forget(struct sock *sk, struct request_sock *req, 945 struct sock *child) 946 { 947 sk->sk_prot->disconnect(child, O_NONBLOCK); 948 949 sock_orphan(child); 950 951 percpu_counter_inc(sk->sk_prot->orphan_count); 952 953 if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(req)->tfo_listener) { 954 BUG_ON(rcu_access_pointer(tcp_sk(child)->fastopen_rsk) != req); 955 BUG_ON(sk != req->rsk_listener); 956 957 /* Paranoid, to prevent race condition if 958 * an inbound pkt destined for child is 959 * blocked by sock lock in tcp_v4_rcv(). 960 * Also to satisfy an assertion in 961 * tcp_v4_destroy_sock(). 962 */ 963 RCU_INIT_POINTER(tcp_sk(child)->fastopen_rsk, NULL); 964 } 965 inet_csk_destroy_sock(child); 966 } 967 968 struct sock *inet_csk_reqsk_queue_add(struct sock *sk, 969 struct request_sock *req, 970 struct sock *child) 971 { 972 struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue; 973 974 spin_lock(&queue->rskq_lock); 975 if (unlikely(sk->sk_state != TCP_LISTEN)) { 976 inet_child_forget(sk, req, child); 977 child = NULL; 978 } else { 979 req->sk = child; 980 req->dl_next = NULL; 981 if (queue->rskq_accept_head == NULL) 982 WRITE_ONCE(queue->rskq_accept_head, req); 983 else 984 queue->rskq_accept_tail->dl_next = req; 985 queue->rskq_accept_tail = req; 986 sk_acceptq_added(sk); 987 } 988 spin_unlock(&queue->rskq_lock); 989 return child; 990 } 991 EXPORT_SYMBOL(inet_csk_reqsk_queue_add); 992 993 struct sock *inet_csk_complete_hashdance(struct sock *sk, struct sock *child, 994 struct request_sock *req, bool own_req) 995 { 996 if (own_req) { 997 inet_csk_reqsk_queue_drop(sk, req); 998 reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req); 999 if (inet_csk_reqsk_queue_add(sk, req, child)) 1000 return child; 1001 } 1002 /* Too bad, another child took ownership of the request, undo. */ 1003 bh_unlock_sock(child); 1004 sock_put(child); 1005 return NULL; 1006 } 1007 EXPORT_SYMBOL(inet_csk_complete_hashdance); 1008 1009 /* 1010 * This routine closes sockets which have been at least partially 1011 * opened, but not yet accepted. 1012 */ 1013 void inet_csk_listen_stop(struct sock *sk) 1014 { 1015 struct inet_connection_sock *icsk = inet_csk(sk); 1016 struct request_sock_queue *queue = &icsk->icsk_accept_queue; 1017 struct request_sock *next, *req; 1018 1019 /* Following specs, it would be better either to send FIN 1020 * (and enter FIN-WAIT-1, it is normal close) 1021 * or to send active reset (abort). 1022 * Certainly, it is pretty dangerous while synflood, but it is 1023 * bad justification for our negligence 8) 1024 * To be honest, we are not able to make either 1025 * of the variants now. --ANK 1026 */ 1027 while ((req = reqsk_queue_remove(queue, sk)) != NULL) { 1028 struct sock *child = req->sk; 1029 1030 local_bh_disable(); 1031 bh_lock_sock(child); 1032 WARN_ON(sock_owned_by_user(child)); 1033 sock_hold(child); 1034 1035 inet_child_forget(sk, req, child); 1036 reqsk_put(req); 1037 bh_unlock_sock(child); 1038 local_bh_enable(); 1039 sock_put(child); 1040 1041 cond_resched(); 1042 } 1043 if (queue->fastopenq.rskq_rst_head) { 1044 /* Free all the reqs queued in rskq_rst_head. */ 1045 spin_lock_bh(&queue->fastopenq.lock); 1046 req = queue->fastopenq.rskq_rst_head; 1047 queue->fastopenq.rskq_rst_head = NULL; 1048 spin_unlock_bh(&queue->fastopenq.lock); 1049 while (req != NULL) { 1050 next = req->dl_next; 1051 reqsk_put(req); 1052 req = next; 1053 } 1054 } 1055 WARN_ON_ONCE(sk->sk_ack_backlog); 1056 } 1057 EXPORT_SYMBOL_GPL(inet_csk_listen_stop); 1058 1059 void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr) 1060 { 1061 struct sockaddr_in *sin = (struct sockaddr_in *)uaddr; 1062 const struct inet_sock *inet = inet_sk(sk); 1063 1064 sin->sin_family = AF_INET; 1065 sin->sin_addr.s_addr = inet->inet_daddr; 1066 sin->sin_port = inet->inet_dport; 1067 } 1068 EXPORT_SYMBOL_GPL(inet_csk_addr2sockaddr); 1069 1070 static struct dst_entry *inet_csk_rebuild_route(struct sock *sk, struct flowi *fl) 1071 { 1072 const struct inet_sock *inet = inet_sk(sk); 1073 const struct ip_options_rcu *inet_opt; 1074 __be32 daddr = inet->inet_daddr; 1075 struct flowi4 *fl4; 1076 struct rtable *rt; 1077 1078 rcu_read_lock(); 1079 inet_opt = rcu_dereference(inet->inet_opt); 1080 if (inet_opt && inet_opt->opt.srr) 1081 daddr = inet_opt->opt.faddr; 1082 fl4 = &fl->u.ip4; 1083 rt = ip_route_output_ports(sock_net(sk), fl4, sk, daddr, 1084 inet->inet_saddr, inet->inet_dport, 1085 inet->inet_sport, sk->sk_protocol, 1086 RT_CONN_FLAGS(sk), sk->sk_bound_dev_if); 1087 if (IS_ERR(rt)) 1088 rt = NULL; 1089 if (rt) 1090 sk_setup_caps(sk, &rt->dst); 1091 rcu_read_unlock(); 1092 1093 return &rt->dst; 1094 } 1095 1096 struct dst_entry *inet_csk_update_pmtu(struct sock *sk, u32 mtu) 1097 { 1098 struct dst_entry *dst = __sk_dst_check(sk, 0); 1099 struct inet_sock *inet = inet_sk(sk); 1100 1101 if (!dst) { 1102 dst = inet_csk_rebuild_route(sk, &inet->cork.fl); 1103 if (!dst) 1104 goto out; 1105 } 1106 dst->ops->update_pmtu(dst, sk, NULL, mtu, true); 1107 1108 dst = __sk_dst_check(sk, 0); 1109 if (!dst) 1110 dst = inet_csk_rebuild_route(sk, &inet->cork.fl); 1111 out: 1112 return dst; 1113 } 1114 EXPORT_SYMBOL_GPL(inet_csk_update_pmtu); 1115