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 * Implementation of the Transmission Control Protocol(TCP). 7 * 8 * IPv4 specific functions 9 * 10 * 11 * code split from: 12 * linux/ipv4/tcp.c 13 * linux/ipv4/tcp_input.c 14 * linux/ipv4/tcp_output.c 15 * 16 * See tcp.c for author information 17 * 18 * This program is free software; you can redistribute it and/or 19 * modify it under the terms of the GNU General Public License 20 * as published by the Free Software Foundation; either version 21 * 2 of the License, or (at your option) any later version. 22 */ 23 24 /* 25 * Changes: 26 * David S. Miller : New socket lookup architecture. 27 * This code is dedicated to John Dyson. 28 * David S. Miller : Change semantics of established hash, 29 * half is devoted to TIME_WAIT sockets 30 * and the rest go in the other half. 31 * Andi Kleen : Add support for syncookies and fixed 32 * some bugs: ip options weren't passed to 33 * the TCP layer, missed a check for an 34 * ACK bit. 35 * Andi Kleen : Implemented fast path mtu discovery. 36 * Fixed many serious bugs in the 37 * request_sock handling and moved 38 * most of it into the af independent code. 39 * Added tail drop and some other bugfixes. 40 * Added new listen semantics. 41 * Mike McLagan : Routing by source 42 * Juan Jose Ciarlante: ip_dynaddr bits 43 * Andi Kleen: various fixes. 44 * Vitaly E. Lavrov : Transparent proxy revived after year 45 * coma. 46 * Andi Kleen : Fix new listen. 47 * Andi Kleen : Fix accept error reporting. 48 * YOSHIFUJI Hideaki @USAGI and: Support IPV6_V6ONLY socket option, which 49 * Alexey Kuznetsov allow both IPv4 and IPv6 sockets to bind 50 * a single port at the same time. 51 */ 52 53 #define pr_fmt(fmt) "TCP: " fmt 54 55 #include <linux/bottom_half.h> 56 #include <linux/types.h> 57 #include <linux/fcntl.h> 58 #include <linux/module.h> 59 #include <linux/random.h> 60 #include <linux/cache.h> 61 #include <linux/jhash.h> 62 #include <linux/init.h> 63 #include <linux/times.h> 64 #include <linux/slab.h> 65 66 #include <net/net_namespace.h> 67 #include <net/icmp.h> 68 #include <net/inet_hashtables.h> 69 #include <net/tcp.h> 70 #include <net/transp_v6.h> 71 #include <net/ipv6.h> 72 #include <net/inet_common.h> 73 #include <net/timewait_sock.h> 74 #include <net/xfrm.h> 75 #include <net/secure_seq.h> 76 #include <net/busy_poll.h> 77 78 #include <linux/inet.h> 79 #include <linux/ipv6.h> 80 #include <linux/stddef.h> 81 #include <linux/proc_fs.h> 82 #include <linux/seq_file.h> 83 84 #include <crypto/hash.h> 85 #include <linux/scatterlist.h> 86 87 int sysctl_tcp_tw_reuse __read_mostly; 88 int sysctl_tcp_low_latency __read_mostly; 89 EXPORT_SYMBOL(sysctl_tcp_low_latency); 90 91 #ifdef CONFIG_TCP_MD5SIG 92 static int tcp_v4_md5_hash_hdr(char *md5_hash, const struct tcp_md5sig_key *key, 93 __be32 daddr, __be32 saddr, const struct tcphdr *th); 94 #endif 95 96 struct inet_hashinfo tcp_hashinfo; 97 EXPORT_SYMBOL(tcp_hashinfo); 98 99 static __u32 tcp_v4_init_sequence(const struct sk_buff *skb) 100 { 101 return secure_tcp_sequence_number(ip_hdr(skb)->daddr, 102 ip_hdr(skb)->saddr, 103 tcp_hdr(skb)->dest, 104 tcp_hdr(skb)->source); 105 } 106 107 int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp) 108 { 109 const struct tcp_timewait_sock *tcptw = tcp_twsk(sktw); 110 struct tcp_sock *tp = tcp_sk(sk); 111 112 /* With PAWS, it is safe from the viewpoint 113 of data integrity. Even without PAWS it is safe provided sequence 114 spaces do not overlap i.e. at data rates <= 80Mbit/sec. 115 116 Actually, the idea is close to VJ's one, only timestamp cache is 117 held not per host, but per port pair and TW bucket is used as state 118 holder. 119 120 If TW bucket has been already destroyed we fall back to VJ's scheme 121 and use initial timestamp retrieved from peer table. 122 */ 123 if (tcptw->tw_ts_recent_stamp && 124 (!twp || (sysctl_tcp_tw_reuse && 125 get_seconds() - tcptw->tw_ts_recent_stamp > 1))) { 126 tp->write_seq = tcptw->tw_snd_nxt + 65535 + 2; 127 if (tp->write_seq == 0) 128 tp->write_seq = 1; 129 tp->rx_opt.ts_recent = tcptw->tw_ts_recent; 130 tp->rx_opt.ts_recent_stamp = tcptw->tw_ts_recent_stamp; 131 sock_hold(sktw); 132 return 1; 133 } 134 135 return 0; 136 } 137 EXPORT_SYMBOL_GPL(tcp_twsk_unique); 138 139 /* This will initiate an outgoing connection. */ 140 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len) 141 { 142 struct sockaddr_in *usin = (struct sockaddr_in *)uaddr; 143 struct inet_sock *inet = inet_sk(sk); 144 struct tcp_sock *tp = tcp_sk(sk); 145 __be16 orig_sport, orig_dport; 146 __be32 daddr, nexthop; 147 struct flowi4 *fl4; 148 struct rtable *rt; 149 int err; 150 struct ip_options_rcu *inet_opt; 151 152 if (addr_len < sizeof(struct sockaddr_in)) 153 return -EINVAL; 154 155 if (usin->sin_family != AF_INET) 156 return -EAFNOSUPPORT; 157 158 nexthop = daddr = usin->sin_addr.s_addr; 159 inet_opt = rcu_dereference_protected(inet->inet_opt, 160 lockdep_sock_is_held(sk)); 161 if (inet_opt && inet_opt->opt.srr) { 162 if (!daddr) 163 return -EINVAL; 164 nexthop = inet_opt->opt.faddr; 165 } 166 167 orig_sport = inet->inet_sport; 168 orig_dport = usin->sin_port; 169 fl4 = &inet->cork.fl.u.ip4; 170 rt = ip_route_connect(fl4, nexthop, inet->inet_saddr, 171 RT_CONN_FLAGS(sk), sk->sk_bound_dev_if, 172 IPPROTO_TCP, 173 orig_sport, orig_dport, sk); 174 if (IS_ERR(rt)) { 175 err = PTR_ERR(rt); 176 if (err == -ENETUNREACH) 177 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES); 178 return err; 179 } 180 181 if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) { 182 ip_rt_put(rt); 183 return -ENETUNREACH; 184 } 185 186 if (!inet_opt || !inet_opt->opt.srr) 187 daddr = fl4->daddr; 188 189 if (!inet->inet_saddr) 190 inet->inet_saddr = fl4->saddr; 191 sk_rcv_saddr_set(sk, inet->inet_saddr); 192 193 if (tp->rx_opt.ts_recent_stamp && inet->inet_daddr != daddr) { 194 /* Reset inherited state */ 195 tp->rx_opt.ts_recent = 0; 196 tp->rx_opt.ts_recent_stamp = 0; 197 if (likely(!tp->repair)) 198 tp->write_seq = 0; 199 } 200 201 if (tcp_death_row.sysctl_tw_recycle && 202 !tp->rx_opt.ts_recent_stamp && fl4->daddr == daddr) 203 tcp_fetch_timewait_stamp(sk, &rt->dst); 204 205 inet->inet_dport = usin->sin_port; 206 sk_daddr_set(sk, daddr); 207 208 inet_csk(sk)->icsk_ext_hdr_len = 0; 209 if (inet_opt) 210 inet_csk(sk)->icsk_ext_hdr_len = inet_opt->opt.optlen; 211 212 tp->rx_opt.mss_clamp = TCP_MSS_DEFAULT; 213 214 /* Socket identity is still unknown (sport may be zero). 215 * However we set state to SYN-SENT and not releasing socket 216 * lock select source port, enter ourselves into the hash tables and 217 * complete initialization after this. 218 */ 219 tcp_set_state(sk, TCP_SYN_SENT); 220 err = inet_hash_connect(&tcp_death_row, sk); 221 if (err) 222 goto failure; 223 224 sk_set_txhash(sk); 225 226 rt = ip_route_newports(fl4, rt, orig_sport, orig_dport, 227 inet->inet_sport, inet->inet_dport, sk); 228 if (IS_ERR(rt)) { 229 err = PTR_ERR(rt); 230 rt = NULL; 231 goto failure; 232 } 233 /* OK, now commit destination to socket. */ 234 sk->sk_gso_type = SKB_GSO_TCPV4; 235 sk_setup_caps(sk, &rt->dst); 236 237 if (!tp->write_seq && likely(!tp->repair)) 238 tp->write_seq = secure_tcp_sequence_number(inet->inet_saddr, 239 inet->inet_daddr, 240 inet->inet_sport, 241 usin->sin_port); 242 243 inet->inet_id = tp->write_seq ^ jiffies; 244 245 err = tcp_connect(sk); 246 247 rt = NULL; 248 if (err) 249 goto failure; 250 251 return 0; 252 253 failure: 254 /* 255 * This unhashes the socket and releases the local port, 256 * if necessary. 257 */ 258 tcp_set_state(sk, TCP_CLOSE); 259 ip_rt_put(rt); 260 sk->sk_route_caps = 0; 261 inet->inet_dport = 0; 262 return err; 263 } 264 EXPORT_SYMBOL(tcp_v4_connect); 265 266 /* 267 * This routine reacts to ICMP_FRAG_NEEDED mtu indications as defined in RFC1191. 268 * It can be called through tcp_release_cb() if socket was owned by user 269 * at the time tcp_v4_err() was called to handle ICMP message. 270 */ 271 void tcp_v4_mtu_reduced(struct sock *sk) 272 { 273 struct dst_entry *dst; 274 struct inet_sock *inet = inet_sk(sk); 275 u32 mtu = tcp_sk(sk)->mtu_info; 276 277 dst = inet_csk_update_pmtu(sk, mtu); 278 if (!dst) 279 return; 280 281 /* Something is about to be wrong... Remember soft error 282 * for the case, if this connection will not able to recover. 283 */ 284 if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst)) 285 sk->sk_err_soft = EMSGSIZE; 286 287 mtu = dst_mtu(dst); 288 289 if (inet->pmtudisc != IP_PMTUDISC_DONT && 290 ip_sk_accept_pmtu(sk) && 291 inet_csk(sk)->icsk_pmtu_cookie > mtu) { 292 tcp_sync_mss(sk, mtu); 293 294 /* Resend the TCP packet because it's 295 * clear that the old packet has been 296 * dropped. This is the new "fast" path mtu 297 * discovery. 298 */ 299 tcp_simple_retransmit(sk); 300 } /* else let the usual retransmit timer handle it */ 301 } 302 EXPORT_SYMBOL(tcp_v4_mtu_reduced); 303 304 static void do_redirect(struct sk_buff *skb, struct sock *sk) 305 { 306 struct dst_entry *dst = __sk_dst_check(sk, 0); 307 308 if (dst) 309 dst->ops->redirect(dst, sk, skb); 310 } 311 312 313 /* handle ICMP messages on TCP_NEW_SYN_RECV request sockets */ 314 void tcp_req_err(struct sock *sk, u32 seq, bool abort) 315 { 316 struct request_sock *req = inet_reqsk(sk); 317 struct net *net = sock_net(sk); 318 319 /* ICMPs are not backlogged, hence we cannot get 320 * an established socket here. 321 */ 322 if (seq != tcp_rsk(req)->snt_isn) { 323 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS); 324 } else if (abort) { 325 /* 326 * Still in SYN_RECV, just remove it silently. 327 * There is no good way to pass the error to the newly 328 * created socket, and POSIX does not want network 329 * errors returned from accept(). 330 */ 331 inet_csk_reqsk_queue_drop(req->rsk_listener, req); 332 tcp_listendrop(req->rsk_listener); 333 } 334 reqsk_put(req); 335 } 336 EXPORT_SYMBOL(tcp_req_err); 337 338 /* 339 * This routine is called by the ICMP module when it gets some 340 * sort of error condition. If err < 0 then the socket should 341 * be closed and the error returned to the user. If err > 0 342 * it's just the icmp type << 8 | icmp code. After adjustment 343 * header points to the first 8 bytes of the tcp header. We need 344 * to find the appropriate port. 345 * 346 * The locking strategy used here is very "optimistic". When 347 * someone else accesses the socket the ICMP is just dropped 348 * and for some paths there is no check at all. 349 * A more general error queue to queue errors for later handling 350 * is probably better. 351 * 352 */ 353 354 void tcp_v4_err(struct sk_buff *icmp_skb, u32 info) 355 { 356 const struct iphdr *iph = (const struct iphdr *)icmp_skb->data; 357 struct tcphdr *th = (struct tcphdr *)(icmp_skb->data + (iph->ihl << 2)); 358 struct inet_connection_sock *icsk; 359 struct tcp_sock *tp; 360 struct inet_sock *inet; 361 const int type = icmp_hdr(icmp_skb)->type; 362 const int code = icmp_hdr(icmp_skb)->code; 363 struct sock *sk; 364 struct sk_buff *skb; 365 struct request_sock *fastopen; 366 __u32 seq, snd_una; 367 __u32 remaining; 368 int err; 369 struct net *net = dev_net(icmp_skb->dev); 370 371 sk = __inet_lookup_established(net, &tcp_hashinfo, iph->daddr, 372 th->dest, iph->saddr, ntohs(th->source), 373 inet_iif(icmp_skb)); 374 if (!sk) { 375 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 376 return; 377 } 378 if (sk->sk_state == TCP_TIME_WAIT) { 379 inet_twsk_put(inet_twsk(sk)); 380 return; 381 } 382 seq = ntohl(th->seq); 383 if (sk->sk_state == TCP_NEW_SYN_RECV) 384 return tcp_req_err(sk, seq, 385 type == ICMP_PARAMETERPROB || 386 type == ICMP_TIME_EXCEEDED || 387 (type == ICMP_DEST_UNREACH && 388 (code == ICMP_NET_UNREACH || 389 code == ICMP_HOST_UNREACH))); 390 391 bh_lock_sock(sk); 392 /* If too many ICMPs get dropped on busy 393 * servers this needs to be solved differently. 394 * We do take care of PMTU discovery (RFC1191) special case : 395 * we can receive locally generated ICMP messages while socket is held. 396 */ 397 if (sock_owned_by_user(sk)) { 398 if (!(type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)) 399 __NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS); 400 } 401 if (sk->sk_state == TCP_CLOSE) 402 goto out; 403 404 if (unlikely(iph->ttl < inet_sk(sk)->min_ttl)) { 405 __NET_INC_STATS(net, LINUX_MIB_TCPMINTTLDROP); 406 goto out; 407 } 408 409 icsk = inet_csk(sk); 410 tp = tcp_sk(sk); 411 /* XXX (TFO) - tp->snd_una should be ISN (tcp_create_openreq_child() */ 412 fastopen = tp->fastopen_rsk; 413 snd_una = fastopen ? tcp_rsk(fastopen)->snt_isn : tp->snd_una; 414 if (sk->sk_state != TCP_LISTEN && 415 !between(seq, snd_una, tp->snd_nxt)) { 416 __NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS); 417 goto out; 418 } 419 420 switch (type) { 421 case ICMP_REDIRECT: 422 do_redirect(icmp_skb, sk); 423 goto out; 424 case ICMP_SOURCE_QUENCH: 425 /* Just silently ignore these. */ 426 goto out; 427 case ICMP_PARAMETERPROB: 428 err = EPROTO; 429 break; 430 case ICMP_DEST_UNREACH: 431 if (code > NR_ICMP_UNREACH) 432 goto out; 433 434 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */ 435 /* We are not interested in TCP_LISTEN and open_requests 436 * (SYN-ACKs send out by Linux are always <576bytes so 437 * they should go through unfragmented). 438 */ 439 if (sk->sk_state == TCP_LISTEN) 440 goto out; 441 442 tp->mtu_info = info; 443 if (!sock_owned_by_user(sk)) { 444 tcp_v4_mtu_reduced(sk); 445 } else { 446 if (!test_and_set_bit(TCP_MTU_REDUCED_DEFERRED, &tp->tsq_flags)) 447 sock_hold(sk); 448 } 449 goto out; 450 } 451 452 err = icmp_err_convert[code].errno; 453 /* check if icmp_skb allows revert of backoff 454 * (see draft-zimmermann-tcp-lcd) */ 455 if (code != ICMP_NET_UNREACH && code != ICMP_HOST_UNREACH) 456 break; 457 if (seq != tp->snd_una || !icsk->icsk_retransmits || 458 !icsk->icsk_backoff || fastopen) 459 break; 460 461 if (sock_owned_by_user(sk)) 462 break; 463 464 icsk->icsk_backoff--; 465 icsk->icsk_rto = tp->srtt_us ? __tcp_set_rto(tp) : 466 TCP_TIMEOUT_INIT; 467 icsk->icsk_rto = inet_csk_rto_backoff(icsk, TCP_RTO_MAX); 468 469 skb = tcp_write_queue_head(sk); 470 BUG_ON(!skb); 471 472 remaining = icsk->icsk_rto - 473 min(icsk->icsk_rto, 474 tcp_time_stamp - tcp_skb_timestamp(skb)); 475 476 if (remaining) { 477 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 478 remaining, TCP_RTO_MAX); 479 } else { 480 /* RTO revert clocked out retransmission. 481 * Will retransmit now */ 482 tcp_retransmit_timer(sk); 483 } 484 485 break; 486 case ICMP_TIME_EXCEEDED: 487 err = EHOSTUNREACH; 488 break; 489 default: 490 goto out; 491 } 492 493 switch (sk->sk_state) { 494 case TCP_SYN_SENT: 495 case TCP_SYN_RECV: 496 /* Only in fast or simultaneous open. If a fast open socket is 497 * is already accepted it is treated as a connected one below. 498 */ 499 if (fastopen && !fastopen->sk) 500 break; 501 502 if (!sock_owned_by_user(sk)) { 503 sk->sk_err = err; 504 505 sk->sk_error_report(sk); 506 507 tcp_done(sk); 508 } else { 509 sk->sk_err_soft = err; 510 } 511 goto out; 512 } 513 514 /* If we've already connected we will keep trying 515 * until we time out, or the user gives up. 516 * 517 * rfc1122 4.2.3.9 allows to consider as hard errors 518 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too, 519 * but it is obsoleted by pmtu discovery). 520 * 521 * Note, that in modern internet, where routing is unreliable 522 * and in each dark corner broken firewalls sit, sending random 523 * errors ordered by their masters even this two messages finally lose 524 * their original sense (even Linux sends invalid PORT_UNREACHs) 525 * 526 * Now we are in compliance with RFCs. 527 * --ANK (980905) 528 */ 529 530 inet = inet_sk(sk); 531 if (!sock_owned_by_user(sk) && inet->recverr) { 532 sk->sk_err = err; 533 sk->sk_error_report(sk); 534 } else { /* Only an error on timeout */ 535 sk->sk_err_soft = err; 536 } 537 538 out: 539 bh_unlock_sock(sk); 540 sock_put(sk); 541 } 542 543 void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr) 544 { 545 struct tcphdr *th = tcp_hdr(skb); 546 547 if (skb->ip_summed == CHECKSUM_PARTIAL) { 548 th->check = ~tcp_v4_check(skb->len, saddr, daddr, 0); 549 skb->csum_start = skb_transport_header(skb) - skb->head; 550 skb->csum_offset = offsetof(struct tcphdr, check); 551 } else { 552 th->check = tcp_v4_check(skb->len, saddr, daddr, 553 csum_partial(th, 554 th->doff << 2, 555 skb->csum)); 556 } 557 } 558 559 /* This routine computes an IPv4 TCP checksum. */ 560 void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb) 561 { 562 const struct inet_sock *inet = inet_sk(sk); 563 564 __tcp_v4_send_check(skb, inet->inet_saddr, inet->inet_daddr); 565 } 566 EXPORT_SYMBOL(tcp_v4_send_check); 567 568 /* 569 * This routine will send an RST to the other tcp. 570 * 571 * Someone asks: why I NEVER use socket parameters (TOS, TTL etc.) 572 * for reset. 573 * Answer: if a packet caused RST, it is not for a socket 574 * existing in our system, if it is matched to a socket, 575 * it is just duplicate segment or bug in other side's TCP. 576 * So that we build reply only basing on parameters 577 * arrived with segment. 578 * Exception: precedence violation. We do not implement it in any case. 579 */ 580 581 static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb) 582 { 583 const struct tcphdr *th = tcp_hdr(skb); 584 struct { 585 struct tcphdr th; 586 #ifdef CONFIG_TCP_MD5SIG 587 __be32 opt[(TCPOLEN_MD5SIG_ALIGNED >> 2)]; 588 #endif 589 } rep; 590 struct ip_reply_arg arg; 591 #ifdef CONFIG_TCP_MD5SIG 592 struct tcp_md5sig_key *key = NULL; 593 const __u8 *hash_location = NULL; 594 unsigned char newhash[16]; 595 int genhash; 596 struct sock *sk1 = NULL; 597 #endif 598 struct net *net; 599 600 /* Never send a reset in response to a reset. */ 601 if (th->rst) 602 return; 603 604 /* If sk not NULL, it means we did a successful lookup and incoming 605 * route had to be correct. prequeue might have dropped our dst. 606 */ 607 if (!sk && skb_rtable(skb)->rt_type != RTN_LOCAL) 608 return; 609 610 /* Swap the send and the receive. */ 611 memset(&rep, 0, sizeof(rep)); 612 rep.th.dest = th->source; 613 rep.th.source = th->dest; 614 rep.th.doff = sizeof(struct tcphdr) / 4; 615 rep.th.rst = 1; 616 617 if (th->ack) { 618 rep.th.seq = th->ack_seq; 619 } else { 620 rep.th.ack = 1; 621 rep.th.ack_seq = htonl(ntohl(th->seq) + th->syn + th->fin + 622 skb->len - (th->doff << 2)); 623 } 624 625 memset(&arg, 0, sizeof(arg)); 626 arg.iov[0].iov_base = (unsigned char *)&rep; 627 arg.iov[0].iov_len = sizeof(rep.th); 628 629 net = sk ? sock_net(sk) : dev_net(skb_dst(skb)->dev); 630 #ifdef CONFIG_TCP_MD5SIG 631 rcu_read_lock(); 632 hash_location = tcp_parse_md5sig_option(th); 633 if (sk && sk_fullsock(sk)) { 634 key = tcp_md5_do_lookup(sk, (union tcp_md5_addr *) 635 &ip_hdr(skb)->saddr, AF_INET); 636 } else if (hash_location) { 637 /* 638 * active side is lost. Try to find listening socket through 639 * source port, and then find md5 key through listening socket. 640 * we are not loose security here: 641 * Incoming packet is checked with md5 hash with finding key, 642 * no RST generated if md5 hash doesn't match. 643 */ 644 sk1 = __inet_lookup_listener(net, &tcp_hashinfo, NULL, 0, 645 ip_hdr(skb)->saddr, 646 th->source, ip_hdr(skb)->daddr, 647 ntohs(th->source), inet_iif(skb)); 648 /* don't send rst if it can't find key */ 649 if (!sk1) 650 goto out; 651 652 key = tcp_md5_do_lookup(sk1, (union tcp_md5_addr *) 653 &ip_hdr(skb)->saddr, AF_INET); 654 if (!key) 655 goto out; 656 657 658 genhash = tcp_v4_md5_hash_skb(newhash, key, NULL, skb); 659 if (genhash || memcmp(hash_location, newhash, 16) != 0) 660 goto out; 661 662 } 663 664 if (key) { 665 rep.opt[0] = htonl((TCPOPT_NOP << 24) | 666 (TCPOPT_NOP << 16) | 667 (TCPOPT_MD5SIG << 8) | 668 TCPOLEN_MD5SIG); 669 /* Update length and the length the header thinks exists */ 670 arg.iov[0].iov_len += TCPOLEN_MD5SIG_ALIGNED; 671 rep.th.doff = arg.iov[0].iov_len / 4; 672 673 tcp_v4_md5_hash_hdr((__u8 *) &rep.opt[1], 674 key, ip_hdr(skb)->saddr, 675 ip_hdr(skb)->daddr, &rep.th); 676 } 677 #endif 678 arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr, 679 ip_hdr(skb)->saddr, /* XXX */ 680 arg.iov[0].iov_len, IPPROTO_TCP, 0); 681 arg.csumoffset = offsetof(struct tcphdr, check) / 2; 682 arg.flags = (sk && inet_sk_transparent(sk)) ? IP_REPLY_ARG_NOSRCCHECK : 0; 683 684 /* When socket is gone, all binding information is lost. 685 * routing might fail in this case. No choice here, if we choose to force 686 * input interface, we will misroute in case of asymmetric route. 687 */ 688 if (sk) 689 arg.bound_dev_if = sk->sk_bound_dev_if; 690 691 BUILD_BUG_ON(offsetof(struct sock, sk_bound_dev_if) != 692 offsetof(struct inet_timewait_sock, tw_bound_dev_if)); 693 694 arg.tos = ip_hdr(skb)->tos; 695 local_bh_disable(); 696 ip_send_unicast_reply(*this_cpu_ptr(net->ipv4.tcp_sk), 697 skb, &TCP_SKB_CB(skb)->header.h4.opt, 698 ip_hdr(skb)->saddr, ip_hdr(skb)->daddr, 699 &arg, arg.iov[0].iov_len); 700 701 __TCP_INC_STATS(net, TCP_MIB_OUTSEGS); 702 __TCP_INC_STATS(net, TCP_MIB_OUTRSTS); 703 local_bh_enable(); 704 705 #ifdef CONFIG_TCP_MD5SIG 706 out: 707 rcu_read_unlock(); 708 #endif 709 } 710 711 /* The code following below sending ACKs in SYN-RECV and TIME-WAIT states 712 outside socket context is ugly, certainly. What can I do? 713 */ 714 715 static void tcp_v4_send_ack(struct net *net, 716 struct sk_buff *skb, u32 seq, u32 ack, 717 u32 win, u32 tsval, u32 tsecr, int oif, 718 struct tcp_md5sig_key *key, 719 int reply_flags, u8 tos) 720 { 721 const struct tcphdr *th = tcp_hdr(skb); 722 struct { 723 struct tcphdr th; 724 __be32 opt[(TCPOLEN_TSTAMP_ALIGNED >> 2) 725 #ifdef CONFIG_TCP_MD5SIG 726 + (TCPOLEN_MD5SIG_ALIGNED >> 2) 727 #endif 728 ]; 729 } rep; 730 struct ip_reply_arg arg; 731 732 memset(&rep.th, 0, sizeof(struct tcphdr)); 733 memset(&arg, 0, sizeof(arg)); 734 735 arg.iov[0].iov_base = (unsigned char *)&rep; 736 arg.iov[0].iov_len = sizeof(rep.th); 737 if (tsecr) { 738 rep.opt[0] = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) | 739 (TCPOPT_TIMESTAMP << 8) | 740 TCPOLEN_TIMESTAMP); 741 rep.opt[1] = htonl(tsval); 742 rep.opt[2] = htonl(tsecr); 743 arg.iov[0].iov_len += TCPOLEN_TSTAMP_ALIGNED; 744 } 745 746 /* Swap the send and the receive. */ 747 rep.th.dest = th->source; 748 rep.th.source = th->dest; 749 rep.th.doff = arg.iov[0].iov_len / 4; 750 rep.th.seq = htonl(seq); 751 rep.th.ack_seq = htonl(ack); 752 rep.th.ack = 1; 753 rep.th.window = htons(win); 754 755 #ifdef CONFIG_TCP_MD5SIG 756 if (key) { 757 int offset = (tsecr) ? 3 : 0; 758 759 rep.opt[offset++] = htonl((TCPOPT_NOP << 24) | 760 (TCPOPT_NOP << 16) | 761 (TCPOPT_MD5SIG << 8) | 762 TCPOLEN_MD5SIG); 763 arg.iov[0].iov_len += TCPOLEN_MD5SIG_ALIGNED; 764 rep.th.doff = arg.iov[0].iov_len/4; 765 766 tcp_v4_md5_hash_hdr((__u8 *) &rep.opt[offset], 767 key, ip_hdr(skb)->saddr, 768 ip_hdr(skb)->daddr, &rep.th); 769 } 770 #endif 771 arg.flags = reply_flags; 772 arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr, 773 ip_hdr(skb)->saddr, /* XXX */ 774 arg.iov[0].iov_len, IPPROTO_TCP, 0); 775 arg.csumoffset = offsetof(struct tcphdr, check) / 2; 776 if (oif) 777 arg.bound_dev_if = oif; 778 arg.tos = tos; 779 local_bh_disable(); 780 ip_send_unicast_reply(*this_cpu_ptr(net->ipv4.tcp_sk), 781 skb, &TCP_SKB_CB(skb)->header.h4.opt, 782 ip_hdr(skb)->saddr, ip_hdr(skb)->daddr, 783 &arg, arg.iov[0].iov_len); 784 785 __TCP_INC_STATS(net, TCP_MIB_OUTSEGS); 786 local_bh_enable(); 787 } 788 789 static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb) 790 { 791 struct inet_timewait_sock *tw = inet_twsk(sk); 792 struct tcp_timewait_sock *tcptw = tcp_twsk(sk); 793 794 tcp_v4_send_ack(sock_net(sk), skb, 795 tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt, 796 tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale, 797 tcp_time_stamp + tcptw->tw_ts_offset, 798 tcptw->tw_ts_recent, 799 tw->tw_bound_dev_if, 800 tcp_twsk_md5_key(tcptw), 801 tw->tw_transparent ? IP_REPLY_ARG_NOSRCCHECK : 0, 802 tw->tw_tos 803 ); 804 805 inet_twsk_put(tw); 806 } 807 808 static void tcp_v4_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb, 809 struct request_sock *req) 810 { 811 /* sk->sk_state == TCP_LISTEN -> for regular TCP_SYN_RECV 812 * sk->sk_state == TCP_SYN_RECV -> for Fast Open. 813 */ 814 u32 seq = (sk->sk_state == TCP_LISTEN) ? tcp_rsk(req)->snt_isn + 1 : 815 tcp_sk(sk)->snd_nxt; 816 817 /* RFC 7323 2.3 818 * The window field (SEG.WND) of every outgoing segment, with the 819 * exception of <SYN> segments, MUST be right-shifted by 820 * Rcv.Wind.Shift bits: 821 */ 822 tcp_v4_send_ack(sock_net(sk), skb, seq, 823 tcp_rsk(req)->rcv_nxt, 824 req->rsk_rcv_wnd >> inet_rsk(req)->rcv_wscale, 825 tcp_time_stamp, 826 req->ts_recent, 827 0, 828 tcp_md5_do_lookup(sk, (union tcp_md5_addr *)&ip_hdr(skb)->daddr, 829 AF_INET), 830 inet_rsk(req)->no_srccheck ? IP_REPLY_ARG_NOSRCCHECK : 0, 831 ip_hdr(skb)->tos); 832 } 833 834 /* 835 * Send a SYN-ACK after having received a SYN. 836 * This still operates on a request_sock only, not on a big 837 * socket. 838 */ 839 static int tcp_v4_send_synack(const struct sock *sk, struct dst_entry *dst, 840 struct flowi *fl, 841 struct request_sock *req, 842 struct tcp_fastopen_cookie *foc, 843 enum tcp_synack_type synack_type) 844 { 845 const struct inet_request_sock *ireq = inet_rsk(req); 846 struct flowi4 fl4; 847 int err = -1; 848 struct sk_buff *skb; 849 850 /* First, grab a route. */ 851 if (!dst && (dst = inet_csk_route_req(sk, &fl4, req)) == NULL) 852 return -1; 853 854 skb = tcp_make_synack(sk, dst, req, foc, synack_type); 855 856 if (skb) { 857 __tcp_v4_send_check(skb, ireq->ir_loc_addr, ireq->ir_rmt_addr); 858 859 err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr, 860 ireq->ir_rmt_addr, 861 ireq->opt); 862 err = net_xmit_eval(err); 863 } 864 865 return err; 866 } 867 868 /* 869 * IPv4 request_sock destructor. 870 */ 871 static void tcp_v4_reqsk_destructor(struct request_sock *req) 872 { 873 kfree(inet_rsk(req)->opt); 874 } 875 876 #ifdef CONFIG_TCP_MD5SIG 877 /* 878 * RFC2385 MD5 checksumming requires a mapping of 879 * IP address->MD5 Key. 880 * We need to maintain these in the sk structure. 881 */ 882 883 /* Find the Key structure for an address. */ 884 struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk, 885 const union tcp_md5_addr *addr, 886 int family) 887 { 888 const struct tcp_sock *tp = tcp_sk(sk); 889 struct tcp_md5sig_key *key; 890 unsigned int size = sizeof(struct in_addr); 891 const struct tcp_md5sig_info *md5sig; 892 893 /* caller either holds rcu_read_lock() or socket lock */ 894 md5sig = rcu_dereference_check(tp->md5sig_info, 895 lockdep_sock_is_held(sk)); 896 if (!md5sig) 897 return NULL; 898 #if IS_ENABLED(CONFIG_IPV6) 899 if (family == AF_INET6) 900 size = sizeof(struct in6_addr); 901 #endif 902 hlist_for_each_entry_rcu(key, &md5sig->head, node) { 903 if (key->family != family) 904 continue; 905 if (!memcmp(&key->addr, addr, size)) 906 return key; 907 } 908 return NULL; 909 } 910 EXPORT_SYMBOL(tcp_md5_do_lookup); 911 912 struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk, 913 const struct sock *addr_sk) 914 { 915 const union tcp_md5_addr *addr; 916 917 addr = (const union tcp_md5_addr *)&addr_sk->sk_daddr; 918 return tcp_md5_do_lookup(sk, addr, AF_INET); 919 } 920 EXPORT_SYMBOL(tcp_v4_md5_lookup); 921 922 /* This can be called on a newly created socket, from other files */ 923 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr, 924 int family, const u8 *newkey, u8 newkeylen, gfp_t gfp) 925 { 926 /* Add Key to the list */ 927 struct tcp_md5sig_key *key; 928 struct tcp_sock *tp = tcp_sk(sk); 929 struct tcp_md5sig_info *md5sig; 930 931 key = tcp_md5_do_lookup(sk, addr, family); 932 if (key) { 933 /* Pre-existing entry - just update that one. */ 934 memcpy(key->key, newkey, newkeylen); 935 key->keylen = newkeylen; 936 return 0; 937 } 938 939 md5sig = rcu_dereference_protected(tp->md5sig_info, 940 lockdep_sock_is_held(sk)); 941 if (!md5sig) { 942 md5sig = kmalloc(sizeof(*md5sig), gfp); 943 if (!md5sig) 944 return -ENOMEM; 945 946 sk_nocaps_add(sk, NETIF_F_GSO_MASK); 947 INIT_HLIST_HEAD(&md5sig->head); 948 rcu_assign_pointer(tp->md5sig_info, md5sig); 949 } 950 951 key = sock_kmalloc(sk, sizeof(*key), gfp); 952 if (!key) 953 return -ENOMEM; 954 if (!tcp_alloc_md5sig_pool()) { 955 sock_kfree_s(sk, key, sizeof(*key)); 956 return -ENOMEM; 957 } 958 959 memcpy(key->key, newkey, newkeylen); 960 key->keylen = newkeylen; 961 key->family = family; 962 memcpy(&key->addr, addr, 963 (family == AF_INET6) ? sizeof(struct in6_addr) : 964 sizeof(struct in_addr)); 965 hlist_add_head_rcu(&key->node, &md5sig->head); 966 return 0; 967 } 968 EXPORT_SYMBOL(tcp_md5_do_add); 969 970 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, int family) 971 { 972 struct tcp_md5sig_key *key; 973 974 key = tcp_md5_do_lookup(sk, addr, family); 975 if (!key) 976 return -ENOENT; 977 hlist_del_rcu(&key->node); 978 atomic_sub(sizeof(*key), &sk->sk_omem_alloc); 979 kfree_rcu(key, rcu); 980 return 0; 981 } 982 EXPORT_SYMBOL(tcp_md5_do_del); 983 984 static void tcp_clear_md5_list(struct sock *sk) 985 { 986 struct tcp_sock *tp = tcp_sk(sk); 987 struct tcp_md5sig_key *key; 988 struct hlist_node *n; 989 struct tcp_md5sig_info *md5sig; 990 991 md5sig = rcu_dereference_protected(tp->md5sig_info, 1); 992 993 hlist_for_each_entry_safe(key, n, &md5sig->head, node) { 994 hlist_del_rcu(&key->node); 995 atomic_sub(sizeof(*key), &sk->sk_omem_alloc); 996 kfree_rcu(key, rcu); 997 } 998 } 999 1000 static int tcp_v4_parse_md5_keys(struct sock *sk, char __user *optval, 1001 int optlen) 1002 { 1003 struct tcp_md5sig cmd; 1004 struct sockaddr_in *sin = (struct sockaddr_in *)&cmd.tcpm_addr; 1005 1006 if (optlen < sizeof(cmd)) 1007 return -EINVAL; 1008 1009 if (copy_from_user(&cmd, optval, sizeof(cmd))) 1010 return -EFAULT; 1011 1012 if (sin->sin_family != AF_INET) 1013 return -EINVAL; 1014 1015 if (!cmd.tcpm_keylen) 1016 return tcp_md5_do_del(sk, (union tcp_md5_addr *)&sin->sin_addr.s_addr, 1017 AF_INET); 1018 1019 if (cmd.tcpm_keylen > TCP_MD5SIG_MAXKEYLEN) 1020 return -EINVAL; 1021 1022 return tcp_md5_do_add(sk, (union tcp_md5_addr *)&sin->sin_addr.s_addr, 1023 AF_INET, cmd.tcpm_key, cmd.tcpm_keylen, 1024 GFP_KERNEL); 1025 } 1026 1027 static int tcp_v4_md5_hash_headers(struct tcp_md5sig_pool *hp, 1028 __be32 daddr, __be32 saddr, 1029 const struct tcphdr *th, int nbytes) 1030 { 1031 struct tcp4_pseudohdr *bp; 1032 struct scatterlist sg; 1033 struct tcphdr *_th; 1034 1035 bp = hp->scratch; 1036 bp->saddr = saddr; 1037 bp->daddr = daddr; 1038 bp->pad = 0; 1039 bp->protocol = IPPROTO_TCP; 1040 bp->len = cpu_to_be16(nbytes); 1041 1042 _th = (struct tcphdr *)(bp + 1); 1043 memcpy(_th, th, sizeof(*th)); 1044 _th->check = 0; 1045 1046 sg_init_one(&sg, bp, sizeof(*bp) + sizeof(*th)); 1047 ahash_request_set_crypt(hp->md5_req, &sg, NULL, 1048 sizeof(*bp) + sizeof(*th)); 1049 return crypto_ahash_update(hp->md5_req); 1050 } 1051 1052 static int tcp_v4_md5_hash_hdr(char *md5_hash, const struct tcp_md5sig_key *key, 1053 __be32 daddr, __be32 saddr, const struct tcphdr *th) 1054 { 1055 struct tcp_md5sig_pool *hp; 1056 struct ahash_request *req; 1057 1058 hp = tcp_get_md5sig_pool(); 1059 if (!hp) 1060 goto clear_hash_noput; 1061 req = hp->md5_req; 1062 1063 if (crypto_ahash_init(req)) 1064 goto clear_hash; 1065 if (tcp_v4_md5_hash_headers(hp, daddr, saddr, th, th->doff << 2)) 1066 goto clear_hash; 1067 if (tcp_md5_hash_key(hp, key)) 1068 goto clear_hash; 1069 ahash_request_set_crypt(req, NULL, md5_hash, 0); 1070 if (crypto_ahash_final(req)) 1071 goto clear_hash; 1072 1073 tcp_put_md5sig_pool(); 1074 return 0; 1075 1076 clear_hash: 1077 tcp_put_md5sig_pool(); 1078 clear_hash_noput: 1079 memset(md5_hash, 0, 16); 1080 return 1; 1081 } 1082 1083 int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key, 1084 const struct sock *sk, 1085 const struct sk_buff *skb) 1086 { 1087 struct tcp_md5sig_pool *hp; 1088 struct ahash_request *req; 1089 const struct tcphdr *th = tcp_hdr(skb); 1090 __be32 saddr, daddr; 1091 1092 if (sk) { /* valid for establish/request sockets */ 1093 saddr = sk->sk_rcv_saddr; 1094 daddr = sk->sk_daddr; 1095 } else { 1096 const struct iphdr *iph = ip_hdr(skb); 1097 saddr = iph->saddr; 1098 daddr = iph->daddr; 1099 } 1100 1101 hp = tcp_get_md5sig_pool(); 1102 if (!hp) 1103 goto clear_hash_noput; 1104 req = hp->md5_req; 1105 1106 if (crypto_ahash_init(req)) 1107 goto clear_hash; 1108 1109 if (tcp_v4_md5_hash_headers(hp, daddr, saddr, th, skb->len)) 1110 goto clear_hash; 1111 if (tcp_md5_hash_skb_data(hp, skb, th->doff << 2)) 1112 goto clear_hash; 1113 if (tcp_md5_hash_key(hp, key)) 1114 goto clear_hash; 1115 ahash_request_set_crypt(req, NULL, md5_hash, 0); 1116 if (crypto_ahash_final(req)) 1117 goto clear_hash; 1118 1119 tcp_put_md5sig_pool(); 1120 return 0; 1121 1122 clear_hash: 1123 tcp_put_md5sig_pool(); 1124 clear_hash_noput: 1125 memset(md5_hash, 0, 16); 1126 return 1; 1127 } 1128 EXPORT_SYMBOL(tcp_v4_md5_hash_skb); 1129 1130 #endif 1131 1132 /* Called with rcu_read_lock() */ 1133 static bool tcp_v4_inbound_md5_hash(const struct sock *sk, 1134 const struct sk_buff *skb) 1135 { 1136 #ifdef CONFIG_TCP_MD5SIG 1137 /* 1138 * This gets called for each TCP segment that arrives 1139 * so we want to be efficient. 1140 * We have 3 drop cases: 1141 * o No MD5 hash and one expected. 1142 * o MD5 hash and we're not expecting one. 1143 * o MD5 hash and its wrong. 1144 */ 1145 const __u8 *hash_location = NULL; 1146 struct tcp_md5sig_key *hash_expected; 1147 const struct iphdr *iph = ip_hdr(skb); 1148 const struct tcphdr *th = tcp_hdr(skb); 1149 int genhash; 1150 unsigned char newhash[16]; 1151 1152 hash_expected = tcp_md5_do_lookup(sk, (union tcp_md5_addr *)&iph->saddr, 1153 AF_INET); 1154 hash_location = tcp_parse_md5sig_option(th); 1155 1156 /* We've parsed the options - do we have a hash? */ 1157 if (!hash_expected && !hash_location) 1158 return false; 1159 1160 if (hash_expected && !hash_location) { 1161 NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5NOTFOUND); 1162 return true; 1163 } 1164 1165 if (!hash_expected && hash_location) { 1166 NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5UNEXPECTED); 1167 return true; 1168 } 1169 1170 /* Okay, so this is hash_expected and hash_location - 1171 * so we need to calculate the checksum. 1172 */ 1173 genhash = tcp_v4_md5_hash_skb(newhash, 1174 hash_expected, 1175 NULL, skb); 1176 1177 if (genhash || memcmp(hash_location, newhash, 16) != 0) { 1178 net_info_ratelimited("MD5 Hash failed for (%pI4, %d)->(%pI4, %d)%s\n", 1179 &iph->saddr, ntohs(th->source), 1180 &iph->daddr, ntohs(th->dest), 1181 genhash ? " tcp_v4_calc_md5_hash failed" 1182 : ""); 1183 return true; 1184 } 1185 return false; 1186 #endif 1187 return false; 1188 } 1189 1190 static void tcp_v4_init_req(struct request_sock *req, 1191 const struct sock *sk_listener, 1192 struct sk_buff *skb) 1193 { 1194 struct inet_request_sock *ireq = inet_rsk(req); 1195 1196 sk_rcv_saddr_set(req_to_sk(req), ip_hdr(skb)->daddr); 1197 sk_daddr_set(req_to_sk(req), ip_hdr(skb)->saddr); 1198 ireq->no_srccheck = inet_sk(sk_listener)->transparent; 1199 ireq->opt = tcp_v4_save_options(skb); 1200 } 1201 1202 static struct dst_entry *tcp_v4_route_req(const struct sock *sk, 1203 struct flowi *fl, 1204 const struct request_sock *req, 1205 bool *strict) 1206 { 1207 struct dst_entry *dst = inet_csk_route_req(sk, &fl->u.ip4, req); 1208 1209 if (strict) { 1210 if (fl->u.ip4.daddr == inet_rsk(req)->ir_rmt_addr) 1211 *strict = true; 1212 else 1213 *strict = false; 1214 } 1215 1216 return dst; 1217 } 1218 1219 struct request_sock_ops tcp_request_sock_ops __read_mostly = { 1220 .family = PF_INET, 1221 .obj_size = sizeof(struct tcp_request_sock), 1222 .rtx_syn_ack = tcp_rtx_synack, 1223 .send_ack = tcp_v4_reqsk_send_ack, 1224 .destructor = tcp_v4_reqsk_destructor, 1225 .send_reset = tcp_v4_send_reset, 1226 .syn_ack_timeout = tcp_syn_ack_timeout, 1227 }; 1228 1229 static const struct tcp_request_sock_ops tcp_request_sock_ipv4_ops = { 1230 .mss_clamp = TCP_MSS_DEFAULT, 1231 #ifdef CONFIG_TCP_MD5SIG 1232 .req_md5_lookup = tcp_v4_md5_lookup, 1233 .calc_md5_hash = tcp_v4_md5_hash_skb, 1234 #endif 1235 .init_req = tcp_v4_init_req, 1236 #ifdef CONFIG_SYN_COOKIES 1237 .cookie_init_seq = cookie_v4_init_sequence, 1238 #endif 1239 .route_req = tcp_v4_route_req, 1240 .init_seq = tcp_v4_init_sequence, 1241 .send_synack = tcp_v4_send_synack, 1242 }; 1243 1244 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb) 1245 { 1246 /* Never answer to SYNs send to broadcast or multicast */ 1247 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 1248 goto drop; 1249 1250 return tcp_conn_request(&tcp_request_sock_ops, 1251 &tcp_request_sock_ipv4_ops, sk, skb); 1252 1253 drop: 1254 tcp_listendrop(sk); 1255 return 0; 1256 } 1257 EXPORT_SYMBOL(tcp_v4_conn_request); 1258 1259 1260 /* 1261 * The three way handshake has completed - we got a valid synack - 1262 * now create the new socket. 1263 */ 1264 struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb, 1265 struct request_sock *req, 1266 struct dst_entry *dst, 1267 struct request_sock *req_unhash, 1268 bool *own_req) 1269 { 1270 struct inet_request_sock *ireq; 1271 struct inet_sock *newinet; 1272 struct tcp_sock *newtp; 1273 struct sock *newsk; 1274 #ifdef CONFIG_TCP_MD5SIG 1275 struct tcp_md5sig_key *key; 1276 #endif 1277 struct ip_options_rcu *inet_opt; 1278 1279 if (sk_acceptq_is_full(sk)) 1280 goto exit_overflow; 1281 1282 newsk = tcp_create_openreq_child(sk, req, skb); 1283 if (!newsk) 1284 goto exit_nonewsk; 1285 1286 newsk->sk_gso_type = SKB_GSO_TCPV4; 1287 inet_sk_rx_dst_set(newsk, skb); 1288 1289 newtp = tcp_sk(newsk); 1290 newinet = inet_sk(newsk); 1291 ireq = inet_rsk(req); 1292 sk_daddr_set(newsk, ireq->ir_rmt_addr); 1293 sk_rcv_saddr_set(newsk, ireq->ir_loc_addr); 1294 newsk->sk_bound_dev_if = ireq->ir_iif; 1295 newinet->inet_saddr = ireq->ir_loc_addr; 1296 inet_opt = ireq->opt; 1297 rcu_assign_pointer(newinet->inet_opt, inet_opt); 1298 ireq->opt = NULL; 1299 newinet->mc_index = inet_iif(skb); 1300 newinet->mc_ttl = ip_hdr(skb)->ttl; 1301 newinet->rcv_tos = ip_hdr(skb)->tos; 1302 inet_csk(newsk)->icsk_ext_hdr_len = 0; 1303 if (inet_opt) 1304 inet_csk(newsk)->icsk_ext_hdr_len = inet_opt->opt.optlen; 1305 newinet->inet_id = newtp->write_seq ^ jiffies; 1306 1307 if (!dst) { 1308 dst = inet_csk_route_child_sock(sk, newsk, req); 1309 if (!dst) 1310 goto put_and_exit; 1311 } else { 1312 /* syncookie case : see end of cookie_v4_check() */ 1313 } 1314 sk_setup_caps(newsk, dst); 1315 1316 tcp_ca_openreq_child(newsk, dst); 1317 1318 tcp_sync_mss(newsk, dst_mtu(dst)); 1319 newtp->advmss = dst_metric_advmss(dst); 1320 if (tcp_sk(sk)->rx_opt.user_mss && 1321 tcp_sk(sk)->rx_opt.user_mss < newtp->advmss) 1322 newtp->advmss = tcp_sk(sk)->rx_opt.user_mss; 1323 1324 tcp_initialize_rcv_mss(newsk); 1325 1326 #ifdef CONFIG_TCP_MD5SIG 1327 /* Copy over the MD5 key from the original socket */ 1328 key = tcp_md5_do_lookup(sk, (union tcp_md5_addr *)&newinet->inet_daddr, 1329 AF_INET); 1330 if (key) { 1331 /* 1332 * We're using one, so create a matching key 1333 * on the newsk structure. If we fail to get 1334 * memory, then we end up not copying the key 1335 * across. Shucks. 1336 */ 1337 tcp_md5_do_add(newsk, (union tcp_md5_addr *)&newinet->inet_daddr, 1338 AF_INET, key->key, key->keylen, GFP_ATOMIC); 1339 sk_nocaps_add(newsk, NETIF_F_GSO_MASK); 1340 } 1341 #endif 1342 1343 if (__inet_inherit_port(sk, newsk) < 0) 1344 goto put_and_exit; 1345 *own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash)); 1346 if (*own_req) 1347 tcp_move_syn(newtp, req); 1348 1349 return newsk; 1350 1351 exit_overflow: 1352 NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS); 1353 exit_nonewsk: 1354 dst_release(dst); 1355 exit: 1356 tcp_listendrop(sk); 1357 return NULL; 1358 put_and_exit: 1359 inet_csk_prepare_forced_close(newsk); 1360 tcp_done(newsk); 1361 goto exit; 1362 } 1363 EXPORT_SYMBOL(tcp_v4_syn_recv_sock); 1364 1365 static struct sock *tcp_v4_cookie_check(struct sock *sk, struct sk_buff *skb) 1366 { 1367 #ifdef CONFIG_SYN_COOKIES 1368 const struct tcphdr *th = tcp_hdr(skb); 1369 1370 if (!th->syn) 1371 sk = cookie_v4_check(sk, skb); 1372 #endif 1373 return sk; 1374 } 1375 1376 /* The socket must have it's spinlock held when we get 1377 * here, unless it is a TCP_LISTEN socket. 1378 * 1379 * We have a potential double-lock case here, so even when 1380 * doing backlog processing we use the BH locking scheme. 1381 * This is because we cannot sleep with the original spinlock 1382 * held. 1383 */ 1384 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb) 1385 { 1386 struct sock *rsk; 1387 1388 if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */ 1389 struct dst_entry *dst = sk->sk_rx_dst; 1390 1391 sock_rps_save_rxhash(sk, skb); 1392 sk_mark_napi_id(sk, skb); 1393 if (dst) { 1394 if (inet_sk(sk)->rx_dst_ifindex != skb->skb_iif || 1395 !dst->ops->check(dst, 0)) { 1396 dst_release(dst); 1397 sk->sk_rx_dst = NULL; 1398 } 1399 } 1400 tcp_rcv_established(sk, skb, tcp_hdr(skb), skb->len); 1401 return 0; 1402 } 1403 1404 if (tcp_checksum_complete(skb)) 1405 goto csum_err; 1406 1407 if (sk->sk_state == TCP_LISTEN) { 1408 struct sock *nsk = tcp_v4_cookie_check(sk, skb); 1409 1410 if (!nsk) 1411 goto discard; 1412 if (nsk != sk) { 1413 sock_rps_save_rxhash(nsk, skb); 1414 sk_mark_napi_id(nsk, skb); 1415 if (tcp_child_process(sk, nsk, skb)) { 1416 rsk = nsk; 1417 goto reset; 1418 } 1419 return 0; 1420 } 1421 } else 1422 sock_rps_save_rxhash(sk, skb); 1423 1424 if (tcp_rcv_state_process(sk, skb)) { 1425 rsk = sk; 1426 goto reset; 1427 } 1428 return 0; 1429 1430 reset: 1431 tcp_v4_send_reset(rsk, skb); 1432 discard: 1433 kfree_skb(skb); 1434 /* Be careful here. If this function gets more complicated and 1435 * gcc suffers from register pressure on the x86, sk (in %ebx) 1436 * might be destroyed here. This current version compiles correctly, 1437 * but you have been warned. 1438 */ 1439 return 0; 1440 1441 csum_err: 1442 TCP_INC_STATS(sock_net(sk), TCP_MIB_CSUMERRORS); 1443 TCP_INC_STATS(sock_net(sk), TCP_MIB_INERRS); 1444 goto discard; 1445 } 1446 EXPORT_SYMBOL(tcp_v4_do_rcv); 1447 1448 void tcp_v4_early_demux(struct sk_buff *skb) 1449 { 1450 const struct iphdr *iph; 1451 const struct tcphdr *th; 1452 struct sock *sk; 1453 1454 if (skb->pkt_type != PACKET_HOST) 1455 return; 1456 1457 if (!pskb_may_pull(skb, skb_transport_offset(skb) + sizeof(struct tcphdr))) 1458 return; 1459 1460 iph = ip_hdr(skb); 1461 th = tcp_hdr(skb); 1462 1463 if (th->doff < sizeof(struct tcphdr) / 4) 1464 return; 1465 1466 sk = __inet_lookup_established(dev_net(skb->dev), &tcp_hashinfo, 1467 iph->saddr, th->source, 1468 iph->daddr, ntohs(th->dest), 1469 skb->skb_iif); 1470 if (sk) { 1471 skb->sk = sk; 1472 skb->destructor = sock_edemux; 1473 if (sk_fullsock(sk)) { 1474 struct dst_entry *dst = READ_ONCE(sk->sk_rx_dst); 1475 1476 if (dst) 1477 dst = dst_check(dst, 0); 1478 if (dst && 1479 inet_sk(sk)->rx_dst_ifindex == skb->skb_iif) 1480 skb_dst_set_noref(skb, dst); 1481 } 1482 } 1483 } 1484 1485 /* Packet is added to VJ-style prequeue for processing in process 1486 * context, if a reader task is waiting. Apparently, this exciting 1487 * idea (VJ's mail "Re: query about TCP header on tcp-ip" of 07 Sep 93) 1488 * failed somewhere. Latency? Burstiness? Well, at least now we will 1489 * see, why it failed. 8)8) --ANK 1490 * 1491 */ 1492 bool tcp_prequeue(struct sock *sk, struct sk_buff *skb) 1493 { 1494 struct tcp_sock *tp = tcp_sk(sk); 1495 1496 if (sysctl_tcp_low_latency || !tp->ucopy.task) 1497 return false; 1498 1499 if (skb->len <= tcp_hdrlen(skb) && 1500 skb_queue_len(&tp->ucopy.prequeue) == 0) 1501 return false; 1502 1503 /* Before escaping RCU protected region, we need to take care of skb 1504 * dst. Prequeue is only enabled for established sockets. 1505 * For such sockets, we might need the skb dst only to set sk->sk_rx_dst 1506 * Instead of doing full sk_rx_dst validity here, let's perform 1507 * an optimistic check. 1508 */ 1509 if (likely(sk->sk_rx_dst)) 1510 skb_dst_drop(skb); 1511 else 1512 skb_dst_force_safe(skb); 1513 1514 __skb_queue_tail(&tp->ucopy.prequeue, skb); 1515 tp->ucopy.memory += skb->truesize; 1516 if (skb_queue_len(&tp->ucopy.prequeue) >= 32 || 1517 tp->ucopy.memory + atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf) { 1518 struct sk_buff *skb1; 1519 1520 BUG_ON(sock_owned_by_user(sk)); 1521 __NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPPREQUEUEDROPPED, 1522 skb_queue_len(&tp->ucopy.prequeue)); 1523 1524 while ((skb1 = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) 1525 sk_backlog_rcv(sk, skb1); 1526 1527 tp->ucopy.memory = 0; 1528 } else if (skb_queue_len(&tp->ucopy.prequeue) == 1) { 1529 wake_up_interruptible_sync_poll(sk_sleep(sk), 1530 POLLIN | POLLRDNORM | POLLRDBAND); 1531 if (!inet_csk_ack_scheduled(sk)) 1532 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 1533 (3 * tcp_rto_min(sk)) / 4, 1534 TCP_RTO_MAX); 1535 } 1536 return true; 1537 } 1538 EXPORT_SYMBOL(tcp_prequeue); 1539 1540 /* 1541 * From tcp_input.c 1542 */ 1543 1544 int tcp_v4_rcv(struct sk_buff *skb) 1545 { 1546 struct net *net = dev_net(skb->dev); 1547 const struct iphdr *iph; 1548 const struct tcphdr *th; 1549 bool refcounted; 1550 struct sock *sk; 1551 int ret; 1552 1553 if (skb->pkt_type != PACKET_HOST) 1554 goto discard_it; 1555 1556 /* Count it even if it's bad */ 1557 __TCP_INC_STATS(net, TCP_MIB_INSEGS); 1558 1559 if (!pskb_may_pull(skb, sizeof(struct tcphdr))) 1560 goto discard_it; 1561 1562 th = (const struct tcphdr *)skb->data; 1563 1564 if (unlikely(th->doff < sizeof(struct tcphdr) / 4)) 1565 goto bad_packet; 1566 if (!pskb_may_pull(skb, th->doff * 4)) 1567 goto discard_it; 1568 1569 /* An explanation is required here, I think. 1570 * Packet length and doff are validated by header prediction, 1571 * provided case of th->doff==0 is eliminated. 1572 * So, we defer the checks. */ 1573 1574 if (skb_checksum_init(skb, IPPROTO_TCP, inet_compute_pseudo)) 1575 goto csum_error; 1576 1577 th = (const struct tcphdr *)skb->data; 1578 iph = ip_hdr(skb); 1579 /* This is tricky : We move IPCB at its correct location into TCP_SKB_CB() 1580 * barrier() makes sure compiler wont play fool^Waliasing games. 1581 */ 1582 memmove(&TCP_SKB_CB(skb)->header.h4, IPCB(skb), 1583 sizeof(struct inet_skb_parm)); 1584 barrier(); 1585 1586 TCP_SKB_CB(skb)->seq = ntohl(th->seq); 1587 TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin + 1588 skb->len - th->doff * 4); 1589 TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq); 1590 TCP_SKB_CB(skb)->tcp_flags = tcp_flag_byte(th); 1591 TCP_SKB_CB(skb)->tcp_tw_isn = 0; 1592 TCP_SKB_CB(skb)->ip_dsfield = ipv4_get_dsfield(iph); 1593 TCP_SKB_CB(skb)->sacked = 0; 1594 1595 lookup: 1596 sk = __inet_lookup_skb(&tcp_hashinfo, skb, __tcp_hdrlen(th), th->source, 1597 th->dest, &refcounted); 1598 if (!sk) 1599 goto no_tcp_socket; 1600 1601 process: 1602 if (sk->sk_state == TCP_TIME_WAIT) 1603 goto do_time_wait; 1604 1605 if (sk->sk_state == TCP_NEW_SYN_RECV) { 1606 struct request_sock *req = inet_reqsk(sk); 1607 struct sock *nsk; 1608 1609 sk = req->rsk_listener; 1610 if (unlikely(tcp_v4_inbound_md5_hash(sk, skb))) { 1611 reqsk_put(req); 1612 goto discard_it; 1613 } 1614 if (unlikely(sk->sk_state != TCP_LISTEN)) { 1615 inet_csk_reqsk_queue_drop_and_put(sk, req); 1616 goto lookup; 1617 } 1618 /* We own a reference on the listener, increase it again 1619 * as we might lose it too soon. 1620 */ 1621 sock_hold(sk); 1622 refcounted = true; 1623 nsk = tcp_check_req(sk, skb, req, false); 1624 if (!nsk) { 1625 reqsk_put(req); 1626 goto discard_and_relse; 1627 } 1628 if (nsk == sk) { 1629 reqsk_put(req); 1630 } else if (tcp_child_process(sk, nsk, skb)) { 1631 tcp_v4_send_reset(nsk, skb); 1632 goto discard_and_relse; 1633 } else { 1634 sock_put(sk); 1635 return 0; 1636 } 1637 } 1638 if (unlikely(iph->ttl < inet_sk(sk)->min_ttl)) { 1639 __NET_INC_STATS(net, LINUX_MIB_TCPMINTTLDROP); 1640 goto discard_and_relse; 1641 } 1642 1643 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) 1644 goto discard_and_relse; 1645 1646 if (tcp_v4_inbound_md5_hash(sk, skb)) 1647 goto discard_and_relse; 1648 1649 nf_reset(skb); 1650 1651 if (sk_filter(sk, skb)) 1652 goto discard_and_relse; 1653 1654 skb->dev = NULL; 1655 1656 if (sk->sk_state == TCP_LISTEN) { 1657 ret = tcp_v4_do_rcv(sk, skb); 1658 goto put_and_return; 1659 } 1660 1661 sk_incoming_cpu_update(sk); 1662 1663 bh_lock_sock_nested(sk); 1664 tcp_segs_in(tcp_sk(sk), skb); 1665 ret = 0; 1666 if (!sock_owned_by_user(sk)) { 1667 if (!tcp_prequeue(sk, skb)) 1668 ret = tcp_v4_do_rcv(sk, skb); 1669 } else if (unlikely(sk_add_backlog(sk, skb, 1670 sk->sk_rcvbuf + sk->sk_sndbuf))) { 1671 bh_unlock_sock(sk); 1672 __NET_INC_STATS(net, LINUX_MIB_TCPBACKLOGDROP); 1673 goto discard_and_relse; 1674 } 1675 bh_unlock_sock(sk); 1676 1677 put_and_return: 1678 if (refcounted) 1679 sock_put(sk); 1680 1681 return ret; 1682 1683 no_tcp_socket: 1684 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) 1685 goto discard_it; 1686 1687 if (tcp_checksum_complete(skb)) { 1688 csum_error: 1689 __TCP_INC_STATS(net, TCP_MIB_CSUMERRORS); 1690 bad_packet: 1691 __TCP_INC_STATS(net, TCP_MIB_INERRS); 1692 } else { 1693 tcp_v4_send_reset(NULL, skb); 1694 } 1695 1696 discard_it: 1697 /* Discard frame. */ 1698 kfree_skb(skb); 1699 return 0; 1700 1701 discard_and_relse: 1702 sk_drops_add(sk, skb); 1703 if (refcounted) 1704 sock_put(sk); 1705 goto discard_it; 1706 1707 do_time_wait: 1708 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { 1709 inet_twsk_put(inet_twsk(sk)); 1710 goto discard_it; 1711 } 1712 1713 if (tcp_checksum_complete(skb)) { 1714 inet_twsk_put(inet_twsk(sk)); 1715 goto csum_error; 1716 } 1717 switch (tcp_timewait_state_process(inet_twsk(sk), skb, th)) { 1718 case TCP_TW_SYN: { 1719 struct sock *sk2 = inet_lookup_listener(dev_net(skb->dev), 1720 &tcp_hashinfo, skb, 1721 __tcp_hdrlen(th), 1722 iph->saddr, th->source, 1723 iph->daddr, th->dest, 1724 inet_iif(skb)); 1725 if (sk2) { 1726 inet_twsk_deschedule_put(inet_twsk(sk)); 1727 sk = sk2; 1728 refcounted = false; 1729 goto process; 1730 } 1731 /* Fall through to ACK */ 1732 } 1733 case TCP_TW_ACK: 1734 tcp_v4_timewait_ack(sk, skb); 1735 break; 1736 case TCP_TW_RST: 1737 tcp_v4_send_reset(sk, skb); 1738 inet_twsk_deschedule_put(inet_twsk(sk)); 1739 goto discard_it; 1740 case TCP_TW_SUCCESS:; 1741 } 1742 goto discard_it; 1743 } 1744 1745 static struct timewait_sock_ops tcp_timewait_sock_ops = { 1746 .twsk_obj_size = sizeof(struct tcp_timewait_sock), 1747 .twsk_unique = tcp_twsk_unique, 1748 .twsk_destructor= tcp_twsk_destructor, 1749 }; 1750 1751 void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb) 1752 { 1753 struct dst_entry *dst = skb_dst(skb); 1754 1755 if (dst && dst_hold_safe(dst)) { 1756 sk->sk_rx_dst = dst; 1757 inet_sk(sk)->rx_dst_ifindex = skb->skb_iif; 1758 } 1759 } 1760 EXPORT_SYMBOL(inet_sk_rx_dst_set); 1761 1762 const struct inet_connection_sock_af_ops ipv4_specific = { 1763 .queue_xmit = ip_queue_xmit, 1764 .send_check = tcp_v4_send_check, 1765 .rebuild_header = inet_sk_rebuild_header, 1766 .sk_rx_dst_set = inet_sk_rx_dst_set, 1767 .conn_request = tcp_v4_conn_request, 1768 .syn_recv_sock = tcp_v4_syn_recv_sock, 1769 .net_header_len = sizeof(struct iphdr), 1770 .setsockopt = ip_setsockopt, 1771 .getsockopt = ip_getsockopt, 1772 .addr2sockaddr = inet_csk_addr2sockaddr, 1773 .sockaddr_len = sizeof(struct sockaddr_in), 1774 .bind_conflict = inet_csk_bind_conflict, 1775 #ifdef CONFIG_COMPAT 1776 .compat_setsockopt = compat_ip_setsockopt, 1777 .compat_getsockopt = compat_ip_getsockopt, 1778 #endif 1779 .mtu_reduced = tcp_v4_mtu_reduced, 1780 }; 1781 EXPORT_SYMBOL(ipv4_specific); 1782 1783 #ifdef CONFIG_TCP_MD5SIG 1784 static const struct tcp_sock_af_ops tcp_sock_ipv4_specific = { 1785 .md5_lookup = tcp_v4_md5_lookup, 1786 .calc_md5_hash = tcp_v4_md5_hash_skb, 1787 .md5_parse = tcp_v4_parse_md5_keys, 1788 }; 1789 #endif 1790 1791 /* NOTE: A lot of things set to zero explicitly by call to 1792 * sk_alloc() so need not be done here. 1793 */ 1794 static int tcp_v4_init_sock(struct sock *sk) 1795 { 1796 struct inet_connection_sock *icsk = inet_csk(sk); 1797 1798 tcp_init_sock(sk); 1799 1800 icsk->icsk_af_ops = &ipv4_specific; 1801 1802 #ifdef CONFIG_TCP_MD5SIG 1803 tcp_sk(sk)->af_specific = &tcp_sock_ipv4_specific; 1804 #endif 1805 1806 return 0; 1807 } 1808 1809 void tcp_v4_destroy_sock(struct sock *sk) 1810 { 1811 struct tcp_sock *tp = tcp_sk(sk); 1812 1813 tcp_clear_xmit_timers(sk); 1814 1815 tcp_cleanup_congestion_control(sk); 1816 1817 /* Cleanup up the write buffer. */ 1818 tcp_write_queue_purge(sk); 1819 1820 /* Cleans up our, hopefully empty, out_of_order_queue. */ 1821 __skb_queue_purge(&tp->out_of_order_queue); 1822 1823 #ifdef CONFIG_TCP_MD5SIG 1824 /* Clean up the MD5 key list, if any */ 1825 if (tp->md5sig_info) { 1826 tcp_clear_md5_list(sk); 1827 kfree_rcu(tp->md5sig_info, rcu); 1828 tp->md5sig_info = NULL; 1829 } 1830 #endif 1831 1832 /* Clean prequeue, it must be empty really */ 1833 __skb_queue_purge(&tp->ucopy.prequeue); 1834 1835 /* Clean up a referenced TCP bind bucket. */ 1836 if (inet_csk(sk)->icsk_bind_hash) 1837 inet_put_port(sk); 1838 1839 BUG_ON(tp->fastopen_rsk); 1840 1841 /* If socket is aborted during connect operation */ 1842 tcp_free_fastopen_req(tp); 1843 tcp_saved_syn_free(tp); 1844 1845 local_bh_disable(); 1846 sk_sockets_allocated_dec(sk); 1847 local_bh_enable(); 1848 1849 if (mem_cgroup_sockets_enabled && sk->sk_memcg) 1850 sock_release_memcg(sk); 1851 } 1852 EXPORT_SYMBOL(tcp_v4_destroy_sock); 1853 1854 #ifdef CONFIG_PROC_FS 1855 /* Proc filesystem TCP sock list dumping. */ 1856 1857 /* 1858 * Get next listener socket follow cur. If cur is NULL, get first socket 1859 * starting from bucket given in st->bucket; when st->bucket is zero the 1860 * very first socket in the hash table is returned. 1861 */ 1862 static void *listening_get_next(struct seq_file *seq, void *cur) 1863 { 1864 struct tcp_iter_state *st = seq->private; 1865 struct net *net = seq_file_net(seq); 1866 struct inet_listen_hashbucket *ilb; 1867 struct inet_connection_sock *icsk; 1868 struct sock *sk = cur; 1869 1870 if (!sk) { 1871 get_head: 1872 ilb = &tcp_hashinfo.listening_hash[st->bucket]; 1873 spin_lock_bh(&ilb->lock); 1874 sk = sk_head(&ilb->head); 1875 st->offset = 0; 1876 goto get_sk; 1877 } 1878 ilb = &tcp_hashinfo.listening_hash[st->bucket]; 1879 ++st->num; 1880 ++st->offset; 1881 1882 sk = sk_next(sk); 1883 get_sk: 1884 sk_for_each_from(sk) { 1885 if (!net_eq(sock_net(sk), net)) 1886 continue; 1887 if (sk->sk_family == st->family) 1888 return sk; 1889 icsk = inet_csk(sk); 1890 } 1891 spin_unlock_bh(&ilb->lock); 1892 st->offset = 0; 1893 if (++st->bucket < INET_LHTABLE_SIZE) 1894 goto get_head; 1895 return NULL; 1896 } 1897 1898 static void *listening_get_idx(struct seq_file *seq, loff_t *pos) 1899 { 1900 struct tcp_iter_state *st = seq->private; 1901 void *rc; 1902 1903 st->bucket = 0; 1904 st->offset = 0; 1905 rc = listening_get_next(seq, NULL); 1906 1907 while (rc && *pos) { 1908 rc = listening_get_next(seq, rc); 1909 --*pos; 1910 } 1911 return rc; 1912 } 1913 1914 static inline bool empty_bucket(const struct tcp_iter_state *st) 1915 { 1916 return hlist_nulls_empty(&tcp_hashinfo.ehash[st->bucket].chain); 1917 } 1918 1919 /* 1920 * Get first established socket starting from bucket given in st->bucket. 1921 * If st->bucket is zero, the very first socket in the hash is returned. 1922 */ 1923 static void *established_get_first(struct seq_file *seq) 1924 { 1925 struct tcp_iter_state *st = seq->private; 1926 struct net *net = seq_file_net(seq); 1927 void *rc = NULL; 1928 1929 st->offset = 0; 1930 for (; st->bucket <= tcp_hashinfo.ehash_mask; ++st->bucket) { 1931 struct sock *sk; 1932 struct hlist_nulls_node *node; 1933 spinlock_t *lock = inet_ehash_lockp(&tcp_hashinfo, st->bucket); 1934 1935 /* Lockless fast path for the common case of empty buckets */ 1936 if (empty_bucket(st)) 1937 continue; 1938 1939 spin_lock_bh(lock); 1940 sk_nulls_for_each(sk, node, &tcp_hashinfo.ehash[st->bucket].chain) { 1941 if (sk->sk_family != st->family || 1942 !net_eq(sock_net(sk), net)) { 1943 continue; 1944 } 1945 rc = sk; 1946 goto out; 1947 } 1948 spin_unlock_bh(lock); 1949 } 1950 out: 1951 return rc; 1952 } 1953 1954 static void *established_get_next(struct seq_file *seq, void *cur) 1955 { 1956 struct sock *sk = cur; 1957 struct hlist_nulls_node *node; 1958 struct tcp_iter_state *st = seq->private; 1959 struct net *net = seq_file_net(seq); 1960 1961 ++st->num; 1962 ++st->offset; 1963 1964 sk = sk_nulls_next(sk); 1965 1966 sk_nulls_for_each_from(sk, node) { 1967 if (sk->sk_family == st->family && net_eq(sock_net(sk), net)) 1968 return sk; 1969 } 1970 1971 spin_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket)); 1972 ++st->bucket; 1973 return established_get_first(seq); 1974 } 1975 1976 static void *established_get_idx(struct seq_file *seq, loff_t pos) 1977 { 1978 struct tcp_iter_state *st = seq->private; 1979 void *rc; 1980 1981 st->bucket = 0; 1982 rc = established_get_first(seq); 1983 1984 while (rc && pos) { 1985 rc = established_get_next(seq, rc); 1986 --pos; 1987 } 1988 return rc; 1989 } 1990 1991 static void *tcp_get_idx(struct seq_file *seq, loff_t pos) 1992 { 1993 void *rc; 1994 struct tcp_iter_state *st = seq->private; 1995 1996 st->state = TCP_SEQ_STATE_LISTENING; 1997 rc = listening_get_idx(seq, &pos); 1998 1999 if (!rc) { 2000 st->state = TCP_SEQ_STATE_ESTABLISHED; 2001 rc = established_get_idx(seq, pos); 2002 } 2003 2004 return rc; 2005 } 2006 2007 static void *tcp_seek_last_pos(struct seq_file *seq) 2008 { 2009 struct tcp_iter_state *st = seq->private; 2010 int offset = st->offset; 2011 int orig_num = st->num; 2012 void *rc = NULL; 2013 2014 switch (st->state) { 2015 case TCP_SEQ_STATE_LISTENING: 2016 if (st->bucket >= INET_LHTABLE_SIZE) 2017 break; 2018 st->state = TCP_SEQ_STATE_LISTENING; 2019 rc = listening_get_next(seq, NULL); 2020 while (offset-- && rc) 2021 rc = listening_get_next(seq, rc); 2022 if (rc) 2023 break; 2024 st->bucket = 0; 2025 st->state = TCP_SEQ_STATE_ESTABLISHED; 2026 /* Fallthrough */ 2027 case TCP_SEQ_STATE_ESTABLISHED: 2028 if (st->bucket > tcp_hashinfo.ehash_mask) 2029 break; 2030 rc = established_get_first(seq); 2031 while (offset-- && rc) 2032 rc = established_get_next(seq, rc); 2033 } 2034 2035 st->num = orig_num; 2036 2037 return rc; 2038 } 2039 2040 static void *tcp_seq_start(struct seq_file *seq, loff_t *pos) 2041 { 2042 struct tcp_iter_state *st = seq->private; 2043 void *rc; 2044 2045 if (*pos && *pos == st->last_pos) { 2046 rc = tcp_seek_last_pos(seq); 2047 if (rc) 2048 goto out; 2049 } 2050 2051 st->state = TCP_SEQ_STATE_LISTENING; 2052 st->num = 0; 2053 st->bucket = 0; 2054 st->offset = 0; 2055 rc = *pos ? tcp_get_idx(seq, *pos - 1) : SEQ_START_TOKEN; 2056 2057 out: 2058 st->last_pos = *pos; 2059 return rc; 2060 } 2061 2062 static void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos) 2063 { 2064 struct tcp_iter_state *st = seq->private; 2065 void *rc = NULL; 2066 2067 if (v == SEQ_START_TOKEN) { 2068 rc = tcp_get_idx(seq, 0); 2069 goto out; 2070 } 2071 2072 switch (st->state) { 2073 case TCP_SEQ_STATE_LISTENING: 2074 rc = listening_get_next(seq, v); 2075 if (!rc) { 2076 st->state = TCP_SEQ_STATE_ESTABLISHED; 2077 st->bucket = 0; 2078 st->offset = 0; 2079 rc = established_get_first(seq); 2080 } 2081 break; 2082 case TCP_SEQ_STATE_ESTABLISHED: 2083 rc = established_get_next(seq, v); 2084 break; 2085 } 2086 out: 2087 ++*pos; 2088 st->last_pos = *pos; 2089 return rc; 2090 } 2091 2092 static void tcp_seq_stop(struct seq_file *seq, void *v) 2093 { 2094 struct tcp_iter_state *st = seq->private; 2095 2096 switch (st->state) { 2097 case TCP_SEQ_STATE_LISTENING: 2098 if (v != SEQ_START_TOKEN) 2099 spin_unlock_bh(&tcp_hashinfo.listening_hash[st->bucket].lock); 2100 break; 2101 case TCP_SEQ_STATE_ESTABLISHED: 2102 if (v) 2103 spin_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket)); 2104 break; 2105 } 2106 } 2107 2108 int tcp_seq_open(struct inode *inode, struct file *file) 2109 { 2110 struct tcp_seq_afinfo *afinfo = PDE_DATA(inode); 2111 struct tcp_iter_state *s; 2112 int err; 2113 2114 err = seq_open_net(inode, file, &afinfo->seq_ops, 2115 sizeof(struct tcp_iter_state)); 2116 if (err < 0) 2117 return err; 2118 2119 s = ((struct seq_file *)file->private_data)->private; 2120 s->family = afinfo->family; 2121 s->last_pos = 0; 2122 return 0; 2123 } 2124 EXPORT_SYMBOL(tcp_seq_open); 2125 2126 int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo) 2127 { 2128 int rc = 0; 2129 struct proc_dir_entry *p; 2130 2131 afinfo->seq_ops.start = tcp_seq_start; 2132 afinfo->seq_ops.next = tcp_seq_next; 2133 afinfo->seq_ops.stop = tcp_seq_stop; 2134 2135 p = proc_create_data(afinfo->name, S_IRUGO, net->proc_net, 2136 afinfo->seq_fops, afinfo); 2137 if (!p) 2138 rc = -ENOMEM; 2139 return rc; 2140 } 2141 EXPORT_SYMBOL(tcp_proc_register); 2142 2143 void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo) 2144 { 2145 remove_proc_entry(afinfo->name, net->proc_net); 2146 } 2147 EXPORT_SYMBOL(tcp_proc_unregister); 2148 2149 static void get_openreq4(const struct request_sock *req, 2150 struct seq_file *f, int i) 2151 { 2152 const struct inet_request_sock *ireq = inet_rsk(req); 2153 long delta = req->rsk_timer.expires - jiffies; 2154 2155 seq_printf(f, "%4d: %08X:%04X %08X:%04X" 2156 " %02X %08X:%08X %02X:%08lX %08X %5u %8d %u %d %pK", 2157 i, 2158 ireq->ir_loc_addr, 2159 ireq->ir_num, 2160 ireq->ir_rmt_addr, 2161 ntohs(ireq->ir_rmt_port), 2162 TCP_SYN_RECV, 2163 0, 0, /* could print option size, but that is af dependent. */ 2164 1, /* timers active (only the expire timer) */ 2165 jiffies_delta_to_clock_t(delta), 2166 req->num_timeout, 2167 from_kuid_munged(seq_user_ns(f), 2168 sock_i_uid(req->rsk_listener)), 2169 0, /* non standard timer */ 2170 0, /* open_requests have no inode */ 2171 0, 2172 req); 2173 } 2174 2175 static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i) 2176 { 2177 int timer_active; 2178 unsigned long timer_expires; 2179 const struct tcp_sock *tp = tcp_sk(sk); 2180 const struct inet_connection_sock *icsk = inet_csk(sk); 2181 const struct inet_sock *inet = inet_sk(sk); 2182 const struct fastopen_queue *fastopenq = &icsk->icsk_accept_queue.fastopenq; 2183 __be32 dest = inet->inet_daddr; 2184 __be32 src = inet->inet_rcv_saddr; 2185 __u16 destp = ntohs(inet->inet_dport); 2186 __u16 srcp = ntohs(inet->inet_sport); 2187 int rx_queue; 2188 int state; 2189 2190 if (icsk->icsk_pending == ICSK_TIME_RETRANS || 2191 icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS || 2192 icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) { 2193 timer_active = 1; 2194 timer_expires = icsk->icsk_timeout; 2195 } else if (icsk->icsk_pending == ICSK_TIME_PROBE0) { 2196 timer_active = 4; 2197 timer_expires = icsk->icsk_timeout; 2198 } else if (timer_pending(&sk->sk_timer)) { 2199 timer_active = 2; 2200 timer_expires = sk->sk_timer.expires; 2201 } else { 2202 timer_active = 0; 2203 timer_expires = jiffies; 2204 } 2205 2206 state = sk_state_load(sk); 2207 if (state == TCP_LISTEN) 2208 rx_queue = sk->sk_ack_backlog; 2209 else 2210 /* Because we don't lock the socket, 2211 * we might find a transient negative value. 2212 */ 2213 rx_queue = max_t(int, tp->rcv_nxt - tp->copied_seq, 0); 2214 2215 seq_printf(f, "%4d: %08X:%04X %08X:%04X %02X %08X:%08X %02X:%08lX " 2216 "%08X %5u %8d %lu %d %pK %lu %lu %u %u %d", 2217 i, src, srcp, dest, destp, state, 2218 tp->write_seq - tp->snd_una, 2219 rx_queue, 2220 timer_active, 2221 jiffies_delta_to_clock_t(timer_expires - jiffies), 2222 icsk->icsk_retransmits, 2223 from_kuid_munged(seq_user_ns(f), sock_i_uid(sk)), 2224 icsk->icsk_probes_out, 2225 sock_i_ino(sk), 2226 atomic_read(&sk->sk_refcnt), sk, 2227 jiffies_to_clock_t(icsk->icsk_rto), 2228 jiffies_to_clock_t(icsk->icsk_ack.ato), 2229 (icsk->icsk_ack.quick << 1) | icsk->icsk_ack.pingpong, 2230 tp->snd_cwnd, 2231 state == TCP_LISTEN ? 2232 fastopenq->max_qlen : 2233 (tcp_in_initial_slowstart(tp) ? -1 : tp->snd_ssthresh)); 2234 } 2235 2236 static void get_timewait4_sock(const struct inet_timewait_sock *tw, 2237 struct seq_file *f, int i) 2238 { 2239 long delta = tw->tw_timer.expires - jiffies; 2240 __be32 dest, src; 2241 __u16 destp, srcp; 2242 2243 dest = tw->tw_daddr; 2244 src = tw->tw_rcv_saddr; 2245 destp = ntohs(tw->tw_dport); 2246 srcp = ntohs(tw->tw_sport); 2247 2248 seq_printf(f, "%4d: %08X:%04X %08X:%04X" 2249 " %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %pK", 2250 i, src, srcp, dest, destp, tw->tw_substate, 0, 0, 2251 3, jiffies_delta_to_clock_t(delta), 0, 0, 0, 0, 2252 atomic_read(&tw->tw_refcnt), tw); 2253 } 2254 2255 #define TMPSZ 150 2256 2257 static int tcp4_seq_show(struct seq_file *seq, void *v) 2258 { 2259 struct tcp_iter_state *st; 2260 struct sock *sk = v; 2261 2262 seq_setwidth(seq, TMPSZ - 1); 2263 if (v == SEQ_START_TOKEN) { 2264 seq_puts(seq, " sl local_address rem_address st tx_queue " 2265 "rx_queue tr tm->when retrnsmt uid timeout " 2266 "inode"); 2267 goto out; 2268 } 2269 st = seq->private; 2270 2271 if (sk->sk_state == TCP_TIME_WAIT) 2272 get_timewait4_sock(v, seq, st->num); 2273 else if (sk->sk_state == TCP_NEW_SYN_RECV) 2274 get_openreq4(v, seq, st->num); 2275 else 2276 get_tcp4_sock(v, seq, st->num); 2277 out: 2278 seq_pad(seq, '\n'); 2279 return 0; 2280 } 2281 2282 static const struct file_operations tcp_afinfo_seq_fops = { 2283 .owner = THIS_MODULE, 2284 .open = tcp_seq_open, 2285 .read = seq_read, 2286 .llseek = seq_lseek, 2287 .release = seq_release_net 2288 }; 2289 2290 static struct tcp_seq_afinfo tcp4_seq_afinfo = { 2291 .name = "tcp", 2292 .family = AF_INET, 2293 .seq_fops = &tcp_afinfo_seq_fops, 2294 .seq_ops = { 2295 .show = tcp4_seq_show, 2296 }, 2297 }; 2298 2299 static int __net_init tcp4_proc_init_net(struct net *net) 2300 { 2301 return tcp_proc_register(net, &tcp4_seq_afinfo); 2302 } 2303 2304 static void __net_exit tcp4_proc_exit_net(struct net *net) 2305 { 2306 tcp_proc_unregister(net, &tcp4_seq_afinfo); 2307 } 2308 2309 static struct pernet_operations tcp4_net_ops = { 2310 .init = tcp4_proc_init_net, 2311 .exit = tcp4_proc_exit_net, 2312 }; 2313 2314 int __init tcp4_proc_init(void) 2315 { 2316 return register_pernet_subsys(&tcp4_net_ops); 2317 } 2318 2319 void tcp4_proc_exit(void) 2320 { 2321 unregister_pernet_subsys(&tcp4_net_ops); 2322 } 2323 #endif /* CONFIG_PROC_FS */ 2324 2325 struct proto tcp_prot = { 2326 .name = "TCP", 2327 .owner = THIS_MODULE, 2328 .close = tcp_close, 2329 .connect = tcp_v4_connect, 2330 .disconnect = tcp_disconnect, 2331 .accept = inet_csk_accept, 2332 .ioctl = tcp_ioctl, 2333 .init = tcp_v4_init_sock, 2334 .destroy = tcp_v4_destroy_sock, 2335 .shutdown = tcp_shutdown, 2336 .setsockopt = tcp_setsockopt, 2337 .getsockopt = tcp_getsockopt, 2338 .recvmsg = tcp_recvmsg, 2339 .sendmsg = tcp_sendmsg, 2340 .sendpage = tcp_sendpage, 2341 .backlog_rcv = tcp_v4_do_rcv, 2342 .release_cb = tcp_release_cb, 2343 .hash = inet_hash, 2344 .unhash = inet_unhash, 2345 .get_port = inet_csk_get_port, 2346 .enter_memory_pressure = tcp_enter_memory_pressure, 2347 .stream_memory_free = tcp_stream_memory_free, 2348 .sockets_allocated = &tcp_sockets_allocated, 2349 .orphan_count = &tcp_orphan_count, 2350 .memory_allocated = &tcp_memory_allocated, 2351 .memory_pressure = &tcp_memory_pressure, 2352 .sysctl_mem = sysctl_tcp_mem, 2353 .sysctl_wmem = sysctl_tcp_wmem, 2354 .sysctl_rmem = sysctl_tcp_rmem, 2355 .max_header = MAX_TCP_HEADER, 2356 .obj_size = sizeof(struct tcp_sock), 2357 .slab_flags = SLAB_DESTROY_BY_RCU, 2358 .twsk_prot = &tcp_timewait_sock_ops, 2359 .rsk_prot = &tcp_request_sock_ops, 2360 .h.hashinfo = &tcp_hashinfo, 2361 .no_autobind = true, 2362 #ifdef CONFIG_COMPAT 2363 .compat_setsockopt = compat_tcp_setsockopt, 2364 .compat_getsockopt = compat_tcp_getsockopt, 2365 #endif 2366 .diag_destroy = tcp_abort, 2367 }; 2368 EXPORT_SYMBOL(tcp_prot); 2369 2370 static void __net_exit tcp_sk_exit(struct net *net) 2371 { 2372 int cpu; 2373 2374 for_each_possible_cpu(cpu) 2375 inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.tcp_sk, cpu)); 2376 free_percpu(net->ipv4.tcp_sk); 2377 } 2378 2379 static int __net_init tcp_sk_init(struct net *net) 2380 { 2381 int res, cpu; 2382 2383 net->ipv4.tcp_sk = alloc_percpu(struct sock *); 2384 if (!net->ipv4.tcp_sk) 2385 return -ENOMEM; 2386 2387 for_each_possible_cpu(cpu) { 2388 struct sock *sk; 2389 2390 res = inet_ctl_sock_create(&sk, PF_INET, SOCK_RAW, 2391 IPPROTO_TCP, net); 2392 if (res) 2393 goto fail; 2394 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE); 2395 *per_cpu_ptr(net->ipv4.tcp_sk, cpu) = sk; 2396 } 2397 2398 net->ipv4.sysctl_tcp_ecn = 2; 2399 net->ipv4.sysctl_tcp_ecn_fallback = 1; 2400 2401 net->ipv4.sysctl_tcp_base_mss = TCP_BASE_MSS; 2402 net->ipv4.sysctl_tcp_probe_threshold = TCP_PROBE_THRESHOLD; 2403 net->ipv4.sysctl_tcp_probe_interval = TCP_PROBE_INTERVAL; 2404 2405 net->ipv4.sysctl_tcp_keepalive_time = TCP_KEEPALIVE_TIME; 2406 net->ipv4.sysctl_tcp_keepalive_probes = TCP_KEEPALIVE_PROBES; 2407 net->ipv4.sysctl_tcp_keepalive_intvl = TCP_KEEPALIVE_INTVL; 2408 2409 net->ipv4.sysctl_tcp_syn_retries = TCP_SYN_RETRIES; 2410 net->ipv4.sysctl_tcp_synack_retries = TCP_SYNACK_RETRIES; 2411 net->ipv4.sysctl_tcp_syncookies = 1; 2412 net->ipv4.sysctl_tcp_reordering = TCP_FASTRETRANS_THRESH; 2413 net->ipv4.sysctl_tcp_retries1 = TCP_RETR1; 2414 net->ipv4.sysctl_tcp_retries2 = TCP_RETR2; 2415 net->ipv4.sysctl_tcp_orphan_retries = 0; 2416 net->ipv4.sysctl_tcp_fin_timeout = TCP_FIN_TIMEOUT; 2417 net->ipv4.sysctl_tcp_notsent_lowat = UINT_MAX; 2418 2419 return 0; 2420 fail: 2421 tcp_sk_exit(net); 2422 2423 return res; 2424 } 2425 2426 static void __net_exit tcp_sk_exit_batch(struct list_head *net_exit_list) 2427 { 2428 inet_twsk_purge(&tcp_hashinfo, &tcp_death_row, AF_INET); 2429 } 2430 2431 static struct pernet_operations __net_initdata tcp_sk_ops = { 2432 .init = tcp_sk_init, 2433 .exit = tcp_sk_exit, 2434 .exit_batch = tcp_sk_exit_batch, 2435 }; 2436 2437 void __init tcp_v4_init(void) 2438 { 2439 inet_hashinfo_init(&tcp_hashinfo); 2440 if (register_pernet_subsys(&tcp_sk_ops)) 2441 panic("Failed to create the TCP control socket.\n"); 2442 } 2443