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 /* Obtain a reference to a local port for the given sock, 300 * if snum is zero it means select any available local port. 301 * We try to allocate an odd port (and leave even ports for connect()) 302 */ 303 int inet_csk_get_port(struct sock *sk, unsigned short snum) 304 { 305 bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN; 306 struct inet_hashinfo *hinfo = sk->sk_prot->h.hashinfo; 307 int ret = 1, port = snum; 308 struct inet_bind_hashbucket *head; 309 struct net *net = sock_net(sk); 310 struct inet_bind_bucket *tb = NULL; 311 kuid_t uid = sock_i_uid(sk); 312 int l3mdev; 313 314 l3mdev = inet_sk_bound_l3mdev(sk); 315 316 if (!port) { 317 head = inet_csk_find_open_port(sk, &tb, &port); 318 if (!head) 319 return ret; 320 if (!tb) 321 goto tb_not_found; 322 goto success; 323 } 324 head = &hinfo->bhash[inet_bhashfn(net, port, 325 hinfo->bhash_size)]; 326 spin_lock_bh(&head->lock); 327 inet_bind_bucket_for_each(tb, &head->chain) 328 if (net_eq(ib_net(tb), net) && tb->l3mdev == l3mdev && 329 tb->port == port) 330 goto tb_found; 331 tb_not_found: 332 tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep, 333 net, head, port, l3mdev); 334 if (!tb) 335 goto fail_unlock; 336 tb_found: 337 if (!hlist_empty(&tb->owners)) { 338 if (sk->sk_reuse == SK_FORCE_REUSE) 339 goto success; 340 341 if ((tb->fastreuse > 0 && reuse) || 342 sk_reuseport_match(tb, sk)) 343 goto success; 344 if (inet_csk_bind_conflict(sk, tb, true, true)) 345 goto fail_unlock; 346 } 347 success: 348 if (hlist_empty(&tb->owners)) { 349 tb->fastreuse = reuse; 350 if (sk->sk_reuseport) { 351 tb->fastreuseport = FASTREUSEPORT_ANY; 352 tb->fastuid = uid; 353 tb->fast_rcv_saddr = sk->sk_rcv_saddr; 354 tb->fast_ipv6_only = ipv6_only_sock(sk); 355 tb->fast_sk_family = sk->sk_family; 356 #if IS_ENABLED(CONFIG_IPV6) 357 tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr; 358 #endif 359 } else { 360 tb->fastreuseport = 0; 361 } 362 } else { 363 if (!reuse) 364 tb->fastreuse = 0; 365 if (sk->sk_reuseport) { 366 /* We didn't match or we don't have fastreuseport set on 367 * the tb, but we have sk_reuseport set on this socket 368 * and we know that there are no bind conflicts with 369 * this socket in this tb, so reset our tb's reuseport 370 * settings so that any subsequent sockets that match 371 * our current socket will be put on the fast path. 372 * 373 * If we reset we need to set FASTREUSEPORT_STRICT so we 374 * do extra checking for all subsequent sk_reuseport 375 * socks. 376 */ 377 if (!sk_reuseport_match(tb, sk)) { 378 tb->fastreuseport = FASTREUSEPORT_STRICT; 379 tb->fastuid = uid; 380 tb->fast_rcv_saddr = sk->sk_rcv_saddr; 381 tb->fast_ipv6_only = ipv6_only_sock(sk); 382 tb->fast_sk_family = sk->sk_family; 383 #if IS_ENABLED(CONFIG_IPV6) 384 tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr; 385 #endif 386 } 387 } else { 388 tb->fastreuseport = 0; 389 } 390 } 391 if (!inet_csk(sk)->icsk_bind_hash) 392 inet_bind_hash(sk, tb, port); 393 WARN_ON(inet_csk(sk)->icsk_bind_hash != tb); 394 ret = 0; 395 396 fail_unlock: 397 spin_unlock_bh(&head->lock); 398 return ret; 399 } 400 EXPORT_SYMBOL_GPL(inet_csk_get_port); 401 402 /* 403 * Wait for an incoming connection, avoid race conditions. This must be called 404 * with the socket locked. 405 */ 406 static int inet_csk_wait_for_connect(struct sock *sk, long timeo) 407 { 408 struct inet_connection_sock *icsk = inet_csk(sk); 409 DEFINE_WAIT(wait); 410 int err; 411 412 /* 413 * True wake-one mechanism for incoming connections: only 414 * one process gets woken up, not the 'whole herd'. 415 * Since we do not 'race & poll' for established sockets 416 * anymore, the common case will execute the loop only once. 417 * 418 * Subtle issue: "add_wait_queue_exclusive()" will be added 419 * after any current non-exclusive waiters, and we know that 420 * it will always _stay_ after any new non-exclusive waiters 421 * because all non-exclusive waiters are added at the 422 * beginning of the wait-queue. As such, it's ok to "drop" 423 * our exclusiveness temporarily when we get woken up without 424 * having to remove and re-insert us on the wait queue. 425 */ 426 for (;;) { 427 prepare_to_wait_exclusive(sk_sleep(sk), &wait, 428 TASK_INTERRUPTIBLE); 429 release_sock(sk); 430 if (reqsk_queue_empty(&icsk->icsk_accept_queue)) 431 timeo = schedule_timeout(timeo); 432 sched_annotate_sleep(); 433 lock_sock(sk); 434 err = 0; 435 if (!reqsk_queue_empty(&icsk->icsk_accept_queue)) 436 break; 437 err = -EINVAL; 438 if (sk->sk_state != TCP_LISTEN) 439 break; 440 err = sock_intr_errno(timeo); 441 if (signal_pending(current)) 442 break; 443 err = -EAGAIN; 444 if (!timeo) 445 break; 446 } 447 finish_wait(sk_sleep(sk), &wait); 448 return err; 449 } 450 451 /* 452 * This will accept the next outstanding connection. 453 */ 454 struct sock *inet_csk_accept(struct sock *sk, int flags, int *err, bool kern) 455 { 456 struct inet_connection_sock *icsk = inet_csk(sk); 457 struct request_sock_queue *queue = &icsk->icsk_accept_queue; 458 struct request_sock *req; 459 struct sock *newsk; 460 int error; 461 462 lock_sock(sk); 463 464 /* We need to make sure that this socket is listening, 465 * and that it has something pending. 466 */ 467 error = -EINVAL; 468 if (sk->sk_state != TCP_LISTEN) 469 goto out_err; 470 471 /* Find already established connection */ 472 if (reqsk_queue_empty(queue)) { 473 long timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK); 474 475 /* If this is a non blocking socket don't sleep */ 476 error = -EAGAIN; 477 if (!timeo) 478 goto out_err; 479 480 error = inet_csk_wait_for_connect(sk, timeo); 481 if (error) 482 goto out_err; 483 } 484 req = reqsk_queue_remove(queue, sk); 485 newsk = req->sk; 486 487 if (sk->sk_protocol == IPPROTO_TCP && 488 tcp_rsk(req)->tfo_listener) { 489 spin_lock_bh(&queue->fastopenq.lock); 490 if (tcp_rsk(req)->tfo_listener) { 491 /* We are still waiting for the final ACK from 3WHS 492 * so can't free req now. Instead, we set req->sk to 493 * NULL to signify that the child socket is taken 494 * so reqsk_fastopen_remove() will free the req 495 * when 3WHS finishes (or is aborted). 496 */ 497 req->sk = NULL; 498 req = NULL; 499 } 500 spin_unlock_bh(&queue->fastopenq.lock); 501 } 502 503 out: 504 release_sock(sk); 505 if (newsk && mem_cgroup_sockets_enabled) { 506 int amt; 507 508 /* atomically get the memory usage, set and charge the 509 * newsk->sk_memcg. 510 */ 511 lock_sock(newsk); 512 513 /* The socket has not been accepted yet, no need to look at 514 * newsk->sk_wmem_queued. 515 */ 516 amt = sk_mem_pages(newsk->sk_forward_alloc + 517 atomic_read(&newsk->sk_rmem_alloc)); 518 mem_cgroup_sk_alloc(newsk); 519 if (newsk->sk_memcg && amt) 520 mem_cgroup_charge_skmem(newsk->sk_memcg, amt); 521 522 release_sock(newsk); 523 } 524 if (req) 525 reqsk_put(req); 526 return newsk; 527 out_err: 528 newsk = NULL; 529 req = NULL; 530 *err = error; 531 goto out; 532 } 533 EXPORT_SYMBOL(inet_csk_accept); 534 535 /* 536 * Using different timers for retransmit, delayed acks and probes 537 * We may wish use just one timer maintaining a list of expire jiffies 538 * to optimize. 539 */ 540 void inet_csk_init_xmit_timers(struct sock *sk, 541 void (*retransmit_handler)(struct timer_list *t), 542 void (*delack_handler)(struct timer_list *t), 543 void (*keepalive_handler)(struct timer_list *t)) 544 { 545 struct inet_connection_sock *icsk = inet_csk(sk); 546 547 timer_setup(&icsk->icsk_retransmit_timer, retransmit_handler, 0); 548 timer_setup(&icsk->icsk_delack_timer, delack_handler, 0); 549 timer_setup(&sk->sk_timer, keepalive_handler, 0); 550 icsk->icsk_pending = icsk->icsk_ack.pending = 0; 551 } 552 EXPORT_SYMBOL(inet_csk_init_xmit_timers); 553 554 void inet_csk_clear_xmit_timers(struct sock *sk) 555 { 556 struct inet_connection_sock *icsk = inet_csk(sk); 557 558 icsk->icsk_pending = icsk->icsk_ack.pending = icsk->icsk_ack.blocked = 0; 559 560 sk_stop_timer(sk, &icsk->icsk_retransmit_timer); 561 sk_stop_timer(sk, &icsk->icsk_delack_timer); 562 sk_stop_timer(sk, &sk->sk_timer); 563 } 564 EXPORT_SYMBOL(inet_csk_clear_xmit_timers); 565 566 void inet_csk_delete_keepalive_timer(struct sock *sk) 567 { 568 sk_stop_timer(sk, &sk->sk_timer); 569 } 570 EXPORT_SYMBOL(inet_csk_delete_keepalive_timer); 571 572 void inet_csk_reset_keepalive_timer(struct sock *sk, unsigned long len) 573 { 574 sk_reset_timer(sk, &sk->sk_timer, jiffies + len); 575 } 576 EXPORT_SYMBOL(inet_csk_reset_keepalive_timer); 577 578 struct dst_entry *inet_csk_route_req(const struct sock *sk, 579 struct flowi4 *fl4, 580 const struct request_sock *req) 581 { 582 const struct inet_request_sock *ireq = inet_rsk(req); 583 struct net *net = read_pnet(&ireq->ireq_net); 584 struct ip_options_rcu *opt; 585 struct rtable *rt; 586 587 rcu_read_lock(); 588 opt = rcu_dereference(ireq->ireq_opt); 589 590 flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark, 591 RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE, 592 sk->sk_protocol, inet_sk_flowi_flags(sk), 593 (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr, 594 ireq->ir_loc_addr, ireq->ir_rmt_port, 595 htons(ireq->ir_num), sk->sk_uid); 596 security_req_classify_flow(req, flowi4_to_flowi(fl4)); 597 rt = ip_route_output_flow(net, fl4, sk); 598 if (IS_ERR(rt)) 599 goto no_route; 600 if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway) 601 goto route_err; 602 rcu_read_unlock(); 603 return &rt->dst; 604 605 route_err: 606 ip_rt_put(rt); 607 no_route: 608 rcu_read_unlock(); 609 __IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES); 610 return NULL; 611 } 612 EXPORT_SYMBOL_GPL(inet_csk_route_req); 613 614 struct dst_entry *inet_csk_route_child_sock(const struct sock *sk, 615 struct sock *newsk, 616 const struct request_sock *req) 617 { 618 const struct inet_request_sock *ireq = inet_rsk(req); 619 struct net *net = read_pnet(&ireq->ireq_net); 620 struct inet_sock *newinet = inet_sk(newsk); 621 struct ip_options_rcu *opt; 622 struct flowi4 *fl4; 623 struct rtable *rt; 624 625 opt = rcu_dereference(ireq->ireq_opt); 626 fl4 = &newinet->cork.fl.u.ip4; 627 628 flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark, 629 RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE, 630 sk->sk_protocol, inet_sk_flowi_flags(sk), 631 (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr, 632 ireq->ir_loc_addr, ireq->ir_rmt_port, 633 htons(ireq->ir_num), sk->sk_uid); 634 security_req_classify_flow(req, flowi4_to_flowi(fl4)); 635 rt = ip_route_output_flow(net, fl4, sk); 636 if (IS_ERR(rt)) 637 goto no_route; 638 if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway) 639 goto route_err; 640 return &rt->dst; 641 642 route_err: 643 ip_rt_put(rt); 644 no_route: 645 __IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES); 646 return NULL; 647 } 648 EXPORT_SYMBOL_GPL(inet_csk_route_child_sock); 649 650 /* Decide when to expire the request and when to resend SYN-ACK */ 651 static inline void syn_ack_recalc(struct request_sock *req, const int thresh, 652 const int max_retries, 653 const u8 rskq_defer_accept, 654 int *expire, int *resend) 655 { 656 if (!rskq_defer_accept) { 657 *expire = req->num_timeout >= thresh; 658 *resend = 1; 659 return; 660 } 661 *expire = req->num_timeout >= thresh && 662 (!inet_rsk(req)->acked || req->num_timeout >= max_retries); 663 /* 664 * Do not resend while waiting for data after ACK, 665 * start to resend on end of deferring period to give 666 * last chance for data or ACK to create established socket. 667 */ 668 *resend = !inet_rsk(req)->acked || 669 req->num_timeout >= rskq_defer_accept - 1; 670 } 671 672 int inet_rtx_syn_ack(const struct sock *parent, struct request_sock *req) 673 { 674 int err = req->rsk_ops->rtx_syn_ack(parent, req); 675 676 if (!err) 677 req->num_retrans++; 678 return err; 679 } 680 EXPORT_SYMBOL(inet_rtx_syn_ack); 681 682 /* return true if req was found in the ehash table */ 683 static bool reqsk_queue_unlink(struct request_sock *req) 684 { 685 struct inet_hashinfo *hashinfo = req_to_sk(req)->sk_prot->h.hashinfo; 686 bool found = false; 687 688 if (sk_hashed(req_to_sk(req))) { 689 spinlock_t *lock = inet_ehash_lockp(hashinfo, req->rsk_hash); 690 691 spin_lock(lock); 692 found = __sk_nulls_del_node_init_rcu(req_to_sk(req)); 693 spin_unlock(lock); 694 } 695 if (timer_pending(&req->rsk_timer) && del_timer_sync(&req->rsk_timer)) 696 reqsk_put(req); 697 return found; 698 } 699 700 void inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req) 701 { 702 if (reqsk_queue_unlink(req)) { 703 reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req); 704 reqsk_put(req); 705 } 706 } 707 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop); 708 709 void inet_csk_reqsk_queue_drop_and_put(struct sock *sk, struct request_sock *req) 710 { 711 inet_csk_reqsk_queue_drop(sk, req); 712 reqsk_put(req); 713 } 714 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop_and_put); 715 716 static void reqsk_timer_handler(struct timer_list *t) 717 { 718 struct request_sock *req = from_timer(req, t, rsk_timer); 719 struct sock *sk_listener = req->rsk_listener; 720 struct net *net = sock_net(sk_listener); 721 struct inet_connection_sock *icsk = inet_csk(sk_listener); 722 struct request_sock_queue *queue = &icsk->icsk_accept_queue; 723 int qlen, expire = 0, resend = 0; 724 int max_retries, thresh; 725 u8 defer_accept; 726 727 if (inet_sk_state_load(sk_listener) != TCP_LISTEN) 728 goto drop; 729 730 max_retries = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_synack_retries; 731 thresh = max_retries; 732 /* Normally all the openreqs are young and become mature 733 * (i.e. converted to established socket) for first timeout. 734 * If synack was not acknowledged for 1 second, it means 735 * one of the following things: synack was lost, ack was lost, 736 * rtt is high or nobody planned to ack (i.e. synflood). 737 * When server is a bit loaded, queue is populated with old 738 * open requests, reducing effective size of queue. 739 * When server is well loaded, queue size reduces to zero 740 * after several minutes of work. It is not synflood, 741 * it is normal operation. The solution is pruning 742 * too old entries overriding normal timeout, when 743 * situation becomes dangerous. 744 * 745 * Essentially, we reserve half of room for young 746 * embrions; and abort old ones without pity, if old 747 * ones are about to clog our table. 748 */ 749 qlen = reqsk_queue_len(queue); 750 if ((qlen << 1) > max(8U, READ_ONCE(sk_listener->sk_max_ack_backlog))) { 751 int young = reqsk_queue_len_young(queue) << 1; 752 753 while (thresh > 2) { 754 if (qlen < young) 755 break; 756 thresh--; 757 young <<= 1; 758 } 759 } 760 defer_accept = READ_ONCE(queue->rskq_defer_accept); 761 if (defer_accept) 762 max_retries = defer_accept; 763 syn_ack_recalc(req, thresh, max_retries, defer_accept, 764 &expire, &resend); 765 req->rsk_ops->syn_ack_timeout(req); 766 if (!expire && 767 (!resend || 768 !inet_rtx_syn_ack(sk_listener, req) || 769 inet_rsk(req)->acked)) { 770 unsigned long timeo; 771 772 if (req->num_timeout++ == 0) 773 atomic_dec(&queue->young); 774 timeo = min(TCP_TIMEOUT_INIT << req->num_timeout, TCP_RTO_MAX); 775 mod_timer(&req->rsk_timer, jiffies + timeo); 776 return; 777 } 778 drop: 779 inet_csk_reqsk_queue_drop_and_put(sk_listener, req); 780 } 781 782 static void reqsk_queue_hash_req(struct request_sock *req, 783 unsigned long timeout) 784 { 785 timer_setup(&req->rsk_timer, reqsk_timer_handler, TIMER_PINNED); 786 mod_timer(&req->rsk_timer, jiffies + timeout); 787 788 inet_ehash_insert(req_to_sk(req), NULL); 789 /* before letting lookups find us, make sure all req fields 790 * are committed to memory and refcnt initialized. 791 */ 792 smp_wmb(); 793 refcount_set(&req->rsk_refcnt, 2 + 1); 794 } 795 796 void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req, 797 unsigned long timeout) 798 { 799 reqsk_queue_hash_req(req, timeout); 800 inet_csk_reqsk_queue_added(sk); 801 } 802 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add); 803 804 static void inet_clone_ulp(const struct request_sock *req, struct sock *newsk, 805 const gfp_t priority) 806 { 807 struct inet_connection_sock *icsk = inet_csk(newsk); 808 809 if (!icsk->icsk_ulp_ops) 810 return; 811 812 if (icsk->icsk_ulp_ops->clone) 813 icsk->icsk_ulp_ops->clone(req, newsk, priority); 814 } 815 816 /** 817 * inet_csk_clone_lock - clone an inet socket, and lock its clone 818 * @sk: the socket to clone 819 * @req: request_sock 820 * @priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc) 821 * 822 * Caller must unlock socket even in error path (bh_unlock_sock(newsk)) 823 */ 824 struct sock *inet_csk_clone_lock(const struct sock *sk, 825 const struct request_sock *req, 826 const gfp_t priority) 827 { 828 struct sock *newsk = sk_clone_lock(sk, priority); 829 830 if (newsk) { 831 struct inet_connection_sock *newicsk = inet_csk(newsk); 832 833 inet_sk_set_state(newsk, TCP_SYN_RECV); 834 newicsk->icsk_bind_hash = NULL; 835 836 inet_sk(newsk)->inet_dport = inet_rsk(req)->ir_rmt_port; 837 inet_sk(newsk)->inet_num = inet_rsk(req)->ir_num; 838 inet_sk(newsk)->inet_sport = htons(inet_rsk(req)->ir_num); 839 840 /* listeners have SOCK_RCU_FREE, not the children */ 841 sock_reset_flag(newsk, SOCK_RCU_FREE); 842 843 inet_sk(newsk)->mc_list = NULL; 844 845 newsk->sk_mark = inet_rsk(req)->ir_mark; 846 atomic64_set(&newsk->sk_cookie, 847 atomic64_read(&inet_rsk(req)->ir_cookie)); 848 849 newicsk->icsk_retransmits = 0; 850 newicsk->icsk_backoff = 0; 851 newicsk->icsk_probes_out = 0; 852 853 /* Deinitialize accept_queue to trap illegal accesses. */ 854 memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue)); 855 856 inet_clone_ulp(req, newsk, priority); 857 858 security_inet_csk_clone(newsk, req); 859 } 860 return newsk; 861 } 862 EXPORT_SYMBOL_GPL(inet_csk_clone_lock); 863 864 /* 865 * At this point, there should be no process reference to this 866 * socket, and thus no user references at all. Therefore we 867 * can assume the socket waitqueue is inactive and nobody will 868 * try to jump onto it. 869 */ 870 void inet_csk_destroy_sock(struct sock *sk) 871 { 872 WARN_ON(sk->sk_state != TCP_CLOSE); 873 WARN_ON(!sock_flag(sk, SOCK_DEAD)); 874 875 /* It cannot be in hash table! */ 876 WARN_ON(!sk_unhashed(sk)); 877 878 /* If it has not 0 inet_sk(sk)->inet_num, it must be bound */ 879 WARN_ON(inet_sk(sk)->inet_num && !inet_csk(sk)->icsk_bind_hash); 880 881 sk->sk_prot->destroy(sk); 882 883 sk_stream_kill_queues(sk); 884 885 xfrm_sk_free_policy(sk); 886 887 sk_refcnt_debug_release(sk); 888 889 percpu_counter_dec(sk->sk_prot->orphan_count); 890 891 sock_put(sk); 892 } 893 EXPORT_SYMBOL(inet_csk_destroy_sock); 894 895 /* This function allows to force a closure of a socket after the call to 896 * tcp/dccp_create_openreq_child(). 897 */ 898 void inet_csk_prepare_forced_close(struct sock *sk) 899 __releases(&sk->sk_lock.slock) 900 { 901 /* sk_clone_lock locked the socket and set refcnt to 2 */ 902 bh_unlock_sock(sk); 903 sock_put(sk); 904 inet_csk_prepare_for_destroy_sock(sk); 905 inet_sk(sk)->inet_num = 0; 906 } 907 EXPORT_SYMBOL(inet_csk_prepare_forced_close); 908 909 int inet_csk_listen_start(struct sock *sk, int backlog) 910 { 911 struct inet_connection_sock *icsk = inet_csk(sk); 912 struct inet_sock *inet = inet_sk(sk); 913 int err = -EADDRINUSE; 914 915 reqsk_queue_alloc(&icsk->icsk_accept_queue); 916 917 sk->sk_ack_backlog = 0; 918 inet_csk_delack_init(sk); 919 920 /* There is race window here: we announce ourselves listening, 921 * but this transition is still not validated by get_port(). 922 * It is OK, because this socket enters to hash table only 923 * after validation is complete. 924 */ 925 inet_sk_state_store(sk, TCP_LISTEN); 926 if (!sk->sk_prot->get_port(sk, inet->inet_num)) { 927 inet->inet_sport = htons(inet->inet_num); 928 929 sk_dst_reset(sk); 930 err = sk->sk_prot->hash(sk); 931 932 if (likely(!err)) 933 return 0; 934 } 935 936 inet_sk_set_state(sk, TCP_CLOSE); 937 return err; 938 } 939 EXPORT_SYMBOL_GPL(inet_csk_listen_start); 940 941 static void inet_child_forget(struct sock *sk, struct request_sock *req, 942 struct sock *child) 943 { 944 sk->sk_prot->disconnect(child, O_NONBLOCK); 945 946 sock_orphan(child); 947 948 percpu_counter_inc(sk->sk_prot->orphan_count); 949 950 if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(req)->tfo_listener) { 951 BUG_ON(rcu_access_pointer(tcp_sk(child)->fastopen_rsk) != req); 952 BUG_ON(sk != req->rsk_listener); 953 954 /* Paranoid, to prevent race condition if 955 * an inbound pkt destined for child is 956 * blocked by sock lock in tcp_v4_rcv(). 957 * Also to satisfy an assertion in 958 * tcp_v4_destroy_sock(). 959 */ 960 RCU_INIT_POINTER(tcp_sk(child)->fastopen_rsk, NULL); 961 } 962 inet_csk_destroy_sock(child); 963 } 964 965 struct sock *inet_csk_reqsk_queue_add(struct sock *sk, 966 struct request_sock *req, 967 struct sock *child) 968 { 969 struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue; 970 971 spin_lock(&queue->rskq_lock); 972 if (unlikely(sk->sk_state != TCP_LISTEN)) { 973 inet_child_forget(sk, req, child); 974 child = NULL; 975 } else { 976 req->sk = child; 977 req->dl_next = NULL; 978 if (queue->rskq_accept_head == NULL) 979 WRITE_ONCE(queue->rskq_accept_head, req); 980 else 981 queue->rskq_accept_tail->dl_next = req; 982 queue->rskq_accept_tail = req; 983 sk_acceptq_added(sk); 984 } 985 spin_unlock(&queue->rskq_lock); 986 return child; 987 } 988 EXPORT_SYMBOL(inet_csk_reqsk_queue_add); 989 990 struct sock *inet_csk_complete_hashdance(struct sock *sk, struct sock *child, 991 struct request_sock *req, bool own_req) 992 { 993 if (own_req) { 994 inet_csk_reqsk_queue_drop(sk, req); 995 reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req); 996 if (inet_csk_reqsk_queue_add(sk, req, child)) 997 return child; 998 } 999 /* Too bad, another child took ownership of the request, undo. */ 1000 bh_unlock_sock(child); 1001 sock_put(child); 1002 return NULL; 1003 } 1004 EXPORT_SYMBOL(inet_csk_complete_hashdance); 1005 1006 /* 1007 * This routine closes sockets which have been at least partially 1008 * opened, but not yet accepted. 1009 */ 1010 void inet_csk_listen_stop(struct sock *sk) 1011 { 1012 struct inet_connection_sock *icsk = inet_csk(sk); 1013 struct request_sock_queue *queue = &icsk->icsk_accept_queue; 1014 struct request_sock *next, *req; 1015 1016 /* Following specs, it would be better either to send FIN 1017 * (and enter FIN-WAIT-1, it is normal close) 1018 * or to send active reset (abort). 1019 * Certainly, it is pretty dangerous while synflood, but it is 1020 * bad justification for our negligence 8) 1021 * To be honest, we are not able to make either 1022 * of the variants now. --ANK 1023 */ 1024 while ((req = reqsk_queue_remove(queue, sk)) != NULL) { 1025 struct sock *child = req->sk; 1026 1027 local_bh_disable(); 1028 bh_lock_sock(child); 1029 WARN_ON(sock_owned_by_user(child)); 1030 sock_hold(child); 1031 1032 inet_child_forget(sk, req, child); 1033 reqsk_put(req); 1034 bh_unlock_sock(child); 1035 local_bh_enable(); 1036 sock_put(child); 1037 1038 cond_resched(); 1039 } 1040 if (queue->fastopenq.rskq_rst_head) { 1041 /* Free all the reqs queued in rskq_rst_head. */ 1042 spin_lock_bh(&queue->fastopenq.lock); 1043 req = queue->fastopenq.rskq_rst_head; 1044 queue->fastopenq.rskq_rst_head = NULL; 1045 spin_unlock_bh(&queue->fastopenq.lock); 1046 while (req != NULL) { 1047 next = req->dl_next; 1048 reqsk_put(req); 1049 req = next; 1050 } 1051 } 1052 WARN_ON_ONCE(sk->sk_ack_backlog); 1053 } 1054 EXPORT_SYMBOL_GPL(inet_csk_listen_stop); 1055 1056 void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr) 1057 { 1058 struct sockaddr_in *sin = (struct sockaddr_in *)uaddr; 1059 const struct inet_sock *inet = inet_sk(sk); 1060 1061 sin->sin_family = AF_INET; 1062 sin->sin_addr.s_addr = inet->inet_daddr; 1063 sin->sin_port = inet->inet_dport; 1064 } 1065 EXPORT_SYMBOL_GPL(inet_csk_addr2sockaddr); 1066 1067 #ifdef CONFIG_COMPAT 1068 int inet_csk_compat_getsockopt(struct sock *sk, int level, int optname, 1069 char __user *optval, int __user *optlen) 1070 { 1071 const struct inet_connection_sock *icsk = inet_csk(sk); 1072 1073 if (icsk->icsk_af_ops->compat_getsockopt) 1074 return icsk->icsk_af_ops->compat_getsockopt(sk, level, optname, 1075 optval, optlen); 1076 return icsk->icsk_af_ops->getsockopt(sk, level, optname, 1077 optval, optlen); 1078 } 1079 EXPORT_SYMBOL_GPL(inet_csk_compat_getsockopt); 1080 1081 int inet_csk_compat_setsockopt(struct sock *sk, int level, int optname, 1082 char __user *optval, unsigned int optlen) 1083 { 1084 const struct inet_connection_sock *icsk = inet_csk(sk); 1085 1086 if (icsk->icsk_af_ops->compat_setsockopt) 1087 return icsk->icsk_af_ops->compat_setsockopt(sk, level, optname, 1088 optval, optlen); 1089 return icsk->icsk_af_ops->setsockopt(sk, level, optname, 1090 optval, optlen); 1091 } 1092 EXPORT_SYMBOL_GPL(inet_csk_compat_setsockopt); 1093 #endif 1094 1095 static struct dst_entry *inet_csk_rebuild_route(struct sock *sk, struct flowi *fl) 1096 { 1097 const struct inet_sock *inet = inet_sk(sk); 1098 const struct ip_options_rcu *inet_opt; 1099 __be32 daddr = inet->inet_daddr; 1100 struct flowi4 *fl4; 1101 struct rtable *rt; 1102 1103 rcu_read_lock(); 1104 inet_opt = rcu_dereference(inet->inet_opt); 1105 if (inet_opt && inet_opt->opt.srr) 1106 daddr = inet_opt->opt.faddr; 1107 fl4 = &fl->u.ip4; 1108 rt = ip_route_output_ports(sock_net(sk), fl4, sk, daddr, 1109 inet->inet_saddr, inet->inet_dport, 1110 inet->inet_sport, sk->sk_protocol, 1111 RT_CONN_FLAGS(sk), sk->sk_bound_dev_if); 1112 if (IS_ERR(rt)) 1113 rt = NULL; 1114 if (rt) 1115 sk_setup_caps(sk, &rt->dst); 1116 rcu_read_unlock(); 1117 1118 return &rt->dst; 1119 } 1120 1121 struct dst_entry *inet_csk_update_pmtu(struct sock *sk, u32 mtu) 1122 { 1123 struct dst_entry *dst = __sk_dst_check(sk, 0); 1124 struct inet_sock *inet = inet_sk(sk); 1125 1126 if (!dst) { 1127 dst = inet_csk_rebuild_route(sk, &inet->cork.fl); 1128 if (!dst) 1129 goto out; 1130 } 1131 dst->ops->update_pmtu(dst, sk, NULL, mtu, true); 1132 1133 dst = __sk_dst_check(sk, 0); 1134 if (!dst) 1135 dst = inet_csk_rebuild_route(sk, &inet->cork.fl); 1136 out: 1137 return dst; 1138 } 1139 EXPORT_SYMBOL_GPL(inet_csk_update_pmtu); 1140