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 tcp_v4_send_ack(sock_net(sk), skb, seq, 818 tcp_rsk(req)->rcv_nxt, req->rsk_rcv_wnd, 819 tcp_time_stamp, 820 req->ts_recent, 821 0, 822 tcp_md5_do_lookup(sk, (union tcp_md5_addr *)&ip_hdr(skb)->daddr, 823 AF_INET), 824 inet_rsk(req)->no_srccheck ? IP_REPLY_ARG_NOSRCCHECK : 0, 825 ip_hdr(skb)->tos); 826 } 827 828 /* 829 * Send a SYN-ACK after having received a SYN. 830 * This still operates on a request_sock only, not on a big 831 * socket. 832 */ 833 static int tcp_v4_send_synack(const struct sock *sk, struct dst_entry *dst, 834 struct flowi *fl, 835 struct request_sock *req, 836 struct tcp_fastopen_cookie *foc, 837 enum tcp_synack_type synack_type) 838 { 839 const struct inet_request_sock *ireq = inet_rsk(req); 840 struct flowi4 fl4; 841 int err = -1; 842 struct sk_buff *skb; 843 844 /* First, grab a route. */ 845 if (!dst && (dst = inet_csk_route_req(sk, &fl4, req)) == NULL) 846 return -1; 847 848 skb = tcp_make_synack(sk, dst, req, foc, synack_type); 849 850 if (skb) { 851 __tcp_v4_send_check(skb, ireq->ir_loc_addr, ireq->ir_rmt_addr); 852 853 err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr, 854 ireq->ir_rmt_addr, 855 ireq->opt); 856 err = net_xmit_eval(err); 857 } 858 859 return err; 860 } 861 862 /* 863 * IPv4 request_sock destructor. 864 */ 865 static void tcp_v4_reqsk_destructor(struct request_sock *req) 866 { 867 kfree(inet_rsk(req)->opt); 868 } 869 870 #ifdef CONFIG_TCP_MD5SIG 871 /* 872 * RFC2385 MD5 checksumming requires a mapping of 873 * IP address->MD5 Key. 874 * We need to maintain these in the sk structure. 875 */ 876 877 /* Find the Key structure for an address. */ 878 struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk, 879 const union tcp_md5_addr *addr, 880 int family) 881 { 882 const struct tcp_sock *tp = tcp_sk(sk); 883 struct tcp_md5sig_key *key; 884 unsigned int size = sizeof(struct in_addr); 885 const struct tcp_md5sig_info *md5sig; 886 887 /* caller either holds rcu_read_lock() or socket lock */ 888 md5sig = rcu_dereference_check(tp->md5sig_info, 889 lockdep_sock_is_held(sk)); 890 if (!md5sig) 891 return NULL; 892 #if IS_ENABLED(CONFIG_IPV6) 893 if (family == AF_INET6) 894 size = sizeof(struct in6_addr); 895 #endif 896 hlist_for_each_entry_rcu(key, &md5sig->head, node) { 897 if (key->family != family) 898 continue; 899 if (!memcmp(&key->addr, addr, size)) 900 return key; 901 } 902 return NULL; 903 } 904 EXPORT_SYMBOL(tcp_md5_do_lookup); 905 906 struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk, 907 const struct sock *addr_sk) 908 { 909 const union tcp_md5_addr *addr; 910 911 addr = (const union tcp_md5_addr *)&addr_sk->sk_daddr; 912 return tcp_md5_do_lookup(sk, addr, AF_INET); 913 } 914 EXPORT_SYMBOL(tcp_v4_md5_lookup); 915 916 /* This can be called on a newly created socket, from other files */ 917 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr, 918 int family, const u8 *newkey, u8 newkeylen, gfp_t gfp) 919 { 920 /* Add Key to the list */ 921 struct tcp_md5sig_key *key; 922 struct tcp_sock *tp = tcp_sk(sk); 923 struct tcp_md5sig_info *md5sig; 924 925 key = tcp_md5_do_lookup(sk, addr, family); 926 if (key) { 927 /* Pre-existing entry - just update that one. */ 928 memcpy(key->key, newkey, newkeylen); 929 key->keylen = newkeylen; 930 return 0; 931 } 932 933 md5sig = rcu_dereference_protected(tp->md5sig_info, 934 lockdep_sock_is_held(sk)); 935 if (!md5sig) { 936 md5sig = kmalloc(sizeof(*md5sig), gfp); 937 if (!md5sig) 938 return -ENOMEM; 939 940 sk_nocaps_add(sk, NETIF_F_GSO_MASK); 941 INIT_HLIST_HEAD(&md5sig->head); 942 rcu_assign_pointer(tp->md5sig_info, md5sig); 943 } 944 945 key = sock_kmalloc(sk, sizeof(*key), gfp); 946 if (!key) 947 return -ENOMEM; 948 if (!tcp_alloc_md5sig_pool()) { 949 sock_kfree_s(sk, key, sizeof(*key)); 950 return -ENOMEM; 951 } 952 953 memcpy(key->key, newkey, newkeylen); 954 key->keylen = newkeylen; 955 key->family = family; 956 memcpy(&key->addr, addr, 957 (family == AF_INET6) ? sizeof(struct in6_addr) : 958 sizeof(struct in_addr)); 959 hlist_add_head_rcu(&key->node, &md5sig->head); 960 return 0; 961 } 962 EXPORT_SYMBOL(tcp_md5_do_add); 963 964 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, int family) 965 { 966 struct tcp_md5sig_key *key; 967 968 key = tcp_md5_do_lookup(sk, addr, family); 969 if (!key) 970 return -ENOENT; 971 hlist_del_rcu(&key->node); 972 atomic_sub(sizeof(*key), &sk->sk_omem_alloc); 973 kfree_rcu(key, rcu); 974 return 0; 975 } 976 EXPORT_SYMBOL(tcp_md5_do_del); 977 978 static void tcp_clear_md5_list(struct sock *sk) 979 { 980 struct tcp_sock *tp = tcp_sk(sk); 981 struct tcp_md5sig_key *key; 982 struct hlist_node *n; 983 struct tcp_md5sig_info *md5sig; 984 985 md5sig = rcu_dereference_protected(tp->md5sig_info, 1); 986 987 hlist_for_each_entry_safe(key, n, &md5sig->head, node) { 988 hlist_del_rcu(&key->node); 989 atomic_sub(sizeof(*key), &sk->sk_omem_alloc); 990 kfree_rcu(key, rcu); 991 } 992 } 993 994 static int tcp_v4_parse_md5_keys(struct sock *sk, char __user *optval, 995 int optlen) 996 { 997 struct tcp_md5sig cmd; 998 struct sockaddr_in *sin = (struct sockaddr_in *)&cmd.tcpm_addr; 999 1000 if (optlen < sizeof(cmd)) 1001 return -EINVAL; 1002 1003 if (copy_from_user(&cmd, optval, sizeof(cmd))) 1004 return -EFAULT; 1005 1006 if (sin->sin_family != AF_INET) 1007 return -EINVAL; 1008 1009 if (!cmd.tcpm_keylen) 1010 return tcp_md5_do_del(sk, (union tcp_md5_addr *)&sin->sin_addr.s_addr, 1011 AF_INET); 1012 1013 if (cmd.tcpm_keylen > TCP_MD5SIG_MAXKEYLEN) 1014 return -EINVAL; 1015 1016 return tcp_md5_do_add(sk, (union tcp_md5_addr *)&sin->sin_addr.s_addr, 1017 AF_INET, cmd.tcpm_key, cmd.tcpm_keylen, 1018 GFP_KERNEL); 1019 } 1020 1021 static int tcp_v4_md5_hash_pseudoheader(struct tcp_md5sig_pool *hp, 1022 __be32 daddr, __be32 saddr, int nbytes) 1023 { 1024 struct tcp4_pseudohdr *bp; 1025 struct scatterlist sg; 1026 1027 bp = &hp->md5_blk.ip4; 1028 1029 /* 1030 * 1. the TCP pseudo-header (in the order: source IP address, 1031 * destination IP address, zero-padded protocol number, and 1032 * segment length) 1033 */ 1034 bp->saddr = saddr; 1035 bp->daddr = daddr; 1036 bp->pad = 0; 1037 bp->protocol = IPPROTO_TCP; 1038 bp->len = cpu_to_be16(nbytes); 1039 1040 sg_init_one(&sg, bp, sizeof(*bp)); 1041 ahash_request_set_crypt(hp->md5_req, &sg, NULL, sizeof(*bp)); 1042 return crypto_ahash_update(hp->md5_req); 1043 } 1044 1045 static int tcp_v4_md5_hash_hdr(char *md5_hash, const struct tcp_md5sig_key *key, 1046 __be32 daddr, __be32 saddr, const struct tcphdr *th) 1047 { 1048 struct tcp_md5sig_pool *hp; 1049 struct ahash_request *req; 1050 1051 hp = tcp_get_md5sig_pool(); 1052 if (!hp) 1053 goto clear_hash_noput; 1054 req = hp->md5_req; 1055 1056 if (crypto_ahash_init(req)) 1057 goto clear_hash; 1058 if (tcp_v4_md5_hash_pseudoheader(hp, daddr, saddr, th->doff << 2)) 1059 goto clear_hash; 1060 if (tcp_md5_hash_header(hp, th)) 1061 goto clear_hash; 1062 if (tcp_md5_hash_key(hp, key)) 1063 goto clear_hash; 1064 ahash_request_set_crypt(req, NULL, md5_hash, 0); 1065 if (crypto_ahash_final(req)) 1066 goto clear_hash; 1067 1068 tcp_put_md5sig_pool(); 1069 return 0; 1070 1071 clear_hash: 1072 tcp_put_md5sig_pool(); 1073 clear_hash_noput: 1074 memset(md5_hash, 0, 16); 1075 return 1; 1076 } 1077 1078 int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key, 1079 const struct sock *sk, 1080 const struct sk_buff *skb) 1081 { 1082 struct tcp_md5sig_pool *hp; 1083 struct ahash_request *req; 1084 const struct tcphdr *th = tcp_hdr(skb); 1085 __be32 saddr, daddr; 1086 1087 if (sk) { /* valid for establish/request sockets */ 1088 saddr = sk->sk_rcv_saddr; 1089 daddr = sk->sk_daddr; 1090 } else { 1091 const struct iphdr *iph = ip_hdr(skb); 1092 saddr = iph->saddr; 1093 daddr = iph->daddr; 1094 } 1095 1096 hp = tcp_get_md5sig_pool(); 1097 if (!hp) 1098 goto clear_hash_noput; 1099 req = hp->md5_req; 1100 1101 if (crypto_ahash_init(req)) 1102 goto clear_hash; 1103 1104 if (tcp_v4_md5_hash_pseudoheader(hp, daddr, saddr, skb->len)) 1105 goto clear_hash; 1106 if (tcp_md5_hash_header(hp, th)) 1107 goto clear_hash; 1108 if (tcp_md5_hash_skb_data(hp, skb, th->doff << 2)) 1109 goto clear_hash; 1110 if (tcp_md5_hash_key(hp, key)) 1111 goto clear_hash; 1112 ahash_request_set_crypt(req, NULL, md5_hash, 0); 1113 if (crypto_ahash_final(req)) 1114 goto clear_hash; 1115 1116 tcp_put_md5sig_pool(); 1117 return 0; 1118 1119 clear_hash: 1120 tcp_put_md5sig_pool(); 1121 clear_hash_noput: 1122 memset(md5_hash, 0, 16); 1123 return 1; 1124 } 1125 EXPORT_SYMBOL(tcp_v4_md5_hash_skb); 1126 1127 #endif 1128 1129 /* Called with rcu_read_lock() */ 1130 static bool tcp_v4_inbound_md5_hash(const struct sock *sk, 1131 const struct sk_buff *skb) 1132 { 1133 #ifdef CONFIG_TCP_MD5SIG 1134 /* 1135 * This gets called for each TCP segment that arrives 1136 * so we want to be efficient. 1137 * We have 3 drop cases: 1138 * o No MD5 hash and one expected. 1139 * o MD5 hash and we're not expecting one. 1140 * o MD5 hash and its wrong. 1141 */ 1142 const __u8 *hash_location = NULL; 1143 struct tcp_md5sig_key *hash_expected; 1144 const struct iphdr *iph = ip_hdr(skb); 1145 const struct tcphdr *th = tcp_hdr(skb); 1146 int genhash; 1147 unsigned char newhash[16]; 1148 1149 hash_expected = tcp_md5_do_lookup(sk, (union tcp_md5_addr *)&iph->saddr, 1150 AF_INET); 1151 hash_location = tcp_parse_md5sig_option(th); 1152 1153 /* We've parsed the options - do we have a hash? */ 1154 if (!hash_expected && !hash_location) 1155 return false; 1156 1157 if (hash_expected && !hash_location) { 1158 NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5NOTFOUND); 1159 return true; 1160 } 1161 1162 if (!hash_expected && hash_location) { 1163 NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5UNEXPECTED); 1164 return true; 1165 } 1166 1167 /* Okay, so this is hash_expected and hash_location - 1168 * so we need to calculate the checksum. 1169 */ 1170 genhash = tcp_v4_md5_hash_skb(newhash, 1171 hash_expected, 1172 NULL, skb); 1173 1174 if (genhash || memcmp(hash_location, newhash, 16) != 0) { 1175 net_info_ratelimited("MD5 Hash failed for (%pI4, %d)->(%pI4, %d)%s\n", 1176 &iph->saddr, ntohs(th->source), 1177 &iph->daddr, ntohs(th->dest), 1178 genhash ? " tcp_v4_calc_md5_hash failed" 1179 : ""); 1180 return true; 1181 } 1182 return false; 1183 #endif 1184 return false; 1185 } 1186 1187 static void tcp_v4_init_req(struct request_sock *req, 1188 const struct sock *sk_listener, 1189 struct sk_buff *skb) 1190 { 1191 struct inet_request_sock *ireq = inet_rsk(req); 1192 1193 sk_rcv_saddr_set(req_to_sk(req), ip_hdr(skb)->daddr); 1194 sk_daddr_set(req_to_sk(req), ip_hdr(skb)->saddr); 1195 ireq->no_srccheck = inet_sk(sk_listener)->transparent; 1196 ireq->opt = tcp_v4_save_options(skb); 1197 } 1198 1199 static struct dst_entry *tcp_v4_route_req(const struct sock *sk, 1200 struct flowi *fl, 1201 const struct request_sock *req, 1202 bool *strict) 1203 { 1204 struct dst_entry *dst = inet_csk_route_req(sk, &fl->u.ip4, req); 1205 1206 if (strict) { 1207 if (fl->u.ip4.daddr == inet_rsk(req)->ir_rmt_addr) 1208 *strict = true; 1209 else 1210 *strict = false; 1211 } 1212 1213 return dst; 1214 } 1215 1216 struct request_sock_ops tcp_request_sock_ops __read_mostly = { 1217 .family = PF_INET, 1218 .obj_size = sizeof(struct tcp_request_sock), 1219 .rtx_syn_ack = tcp_rtx_synack, 1220 .send_ack = tcp_v4_reqsk_send_ack, 1221 .destructor = tcp_v4_reqsk_destructor, 1222 .send_reset = tcp_v4_send_reset, 1223 .syn_ack_timeout = tcp_syn_ack_timeout, 1224 }; 1225 1226 static const struct tcp_request_sock_ops tcp_request_sock_ipv4_ops = { 1227 .mss_clamp = TCP_MSS_DEFAULT, 1228 #ifdef CONFIG_TCP_MD5SIG 1229 .req_md5_lookup = tcp_v4_md5_lookup, 1230 .calc_md5_hash = tcp_v4_md5_hash_skb, 1231 #endif 1232 .init_req = tcp_v4_init_req, 1233 #ifdef CONFIG_SYN_COOKIES 1234 .cookie_init_seq = cookie_v4_init_sequence, 1235 #endif 1236 .route_req = tcp_v4_route_req, 1237 .init_seq = tcp_v4_init_sequence, 1238 .send_synack = tcp_v4_send_synack, 1239 }; 1240 1241 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb) 1242 { 1243 /* Never answer to SYNs send to broadcast or multicast */ 1244 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 1245 goto drop; 1246 1247 return tcp_conn_request(&tcp_request_sock_ops, 1248 &tcp_request_sock_ipv4_ops, sk, skb); 1249 1250 drop: 1251 tcp_listendrop(sk); 1252 return 0; 1253 } 1254 EXPORT_SYMBOL(tcp_v4_conn_request); 1255 1256 1257 /* 1258 * The three way handshake has completed - we got a valid synack - 1259 * now create the new socket. 1260 */ 1261 struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb, 1262 struct request_sock *req, 1263 struct dst_entry *dst, 1264 struct request_sock *req_unhash, 1265 bool *own_req) 1266 { 1267 struct inet_request_sock *ireq; 1268 struct inet_sock *newinet; 1269 struct tcp_sock *newtp; 1270 struct sock *newsk; 1271 #ifdef CONFIG_TCP_MD5SIG 1272 struct tcp_md5sig_key *key; 1273 #endif 1274 struct ip_options_rcu *inet_opt; 1275 1276 if (sk_acceptq_is_full(sk)) 1277 goto exit_overflow; 1278 1279 newsk = tcp_create_openreq_child(sk, req, skb); 1280 if (!newsk) 1281 goto exit_nonewsk; 1282 1283 newsk->sk_gso_type = SKB_GSO_TCPV4; 1284 inet_sk_rx_dst_set(newsk, skb); 1285 1286 newtp = tcp_sk(newsk); 1287 newinet = inet_sk(newsk); 1288 ireq = inet_rsk(req); 1289 sk_daddr_set(newsk, ireq->ir_rmt_addr); 1290 sk_rcv_saddr_set(newsk, ireq->ir_loc_addr); 1291 newsk->sk_bound_dev_if = ireq->ir_iif; 1292 newinet->inet_saddr = ireq->ir_loc_addr; 1293 inet_opt = ireq->opt; 1294 rcu_assign_pointer(newinet->inet_opt, inet_opt); 1295 ireq->opt = NULL; 1296 newinet->mc_index = inet_iif(skb); 1297 newinet->mc_ttl = ip_hdr(skb)->ttl; 1298 newinet->rcv_tos = ip_hdr(skb)->tos; 1299 inet_csk(newsk)->icsk_ext_hdr_len = 0; 1300 if (inet_opt) 1301 inet_csk(newsk)->icsk_ext_hdr_len = inet_opt->opt.optlen; 1302 newinet->inet_id = newtp->write_seq ^ jiffies; 1303 1304 if (!dst) { 1305 dst = inet_csk_route_child_sock(sk, newsk, req); 1306 if (!dst) 1307 goto put_and_exit; 1308 } else { 1309 /* syncookie case : see end of cookie_v4_check() */ 1310 } 1311 sk_setup_caps(newsk, dst); 1312 1313 tcp_ca_openreq_child(newsk, dst); 1314 1315 tcp_sync_mss(newsk, dst_mtu(dst)); 1316 newtp->advmss = dst_metric_advmss(dst); 1317 if (tcp_sk(sk)->rx_opt.user_mss && 1318 tcp_sk(sk)->rx_opt.user_mss < newtp->advmss) 1319 newtp->advmss = tcp_sk(sk)->rx_opt.user_mss; 1320 1321 tcp_initialize_rcv_mss(newsk); 1322 1323 #ifdef CONFIG_TCP_MD5SIG 1324 /* Copy over the MD5 key from the original socket */ 1325 key = tcp_md5_do_lookup(sk, (union tcp_md5_addr *)&newinet->inet_daddr, 1326 AF_INET); 1327 if (key) { 1328 /* 1329 * We're using one, so create a matching key 1330 * on the newsk structure. If we fail to get 1331 * memory, then we end up not copying the key 1332 * across. Shucks. 1333 */ 1334 tcp_md5_do_add(newsk, (union tcp_md5_addr *)&newinet->inet_daddr, 1335 AF_INET, key->key, key->keylen, GFP_ATOMIC); 1336 sk_nocaps_add(newsk, NETIF_F_GSO_MASK); 1337 } 1338 #endif 1339 1340 if (__inet_inherit_port(sk, newsk) < 0) 1341 goto put_and_exit; 1342 *own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash)); 1343 if (*own_req) 1344 tcp_move_syn(newtp, req); 1345 1346 return newsk; 1347 1348 exit_overflow: 1349 NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS); 1350 exit_nonewsk: 1351 dst_release(dst); 1352 exit: 1353 tcp_listendrop(sk); 1354 return NULL; 1355 put_and_exit: 1356 inet_csk_prepare_forced_close(newsk); 1357 tcp_done(newsk); 1358 goto exit; 1359 } 1360 EXPORT_SYMBOL(tcp_v4_syn_recv_sock); 1361 1362 static struct sock *tcp_v4_cookie_check(struct sock *sk, struct sk_buff *skb) 1363 { 1364 #ifdef CONFIG_SYN_COOKIES 1365 const struct tcphdr *th = tcp_hdr(skb); 1366 1367 if (!th->syn) 1368 sk = cookie_v4_check(sk, skb); 1369 #endif 1370 return sk; 1371 } 1372 1373 /* The socket must have it's spinlock held when we get 1374 * here, unless it is a TCP_LISTEN socket. 1375 * 1376 * We have a potential double-lock case here, so even when 1377 * doing backlog processing we use the BH locking scheme. 1378 * This is because we cannot sleep with the original spinlock 1379 * held. 1380 */ 1381 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb) 1382 { 1383 struct sock *rsk; 1384 1385 if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */ 1386 struct dst_entry *dst = sk->sk_rx_dst; 1387 1388 sock_rps_save_rxhash(sk, skb); 1389 sk_mark_napi_id(sk, skb); 1390 if (dst) { 1391 if (inet_sk(sk)->rx_dst_ifindex != skb->skb_iif || 1392 !dst->ops->check(dst, 0)) { 1393 dst_release(dst); 1394 sk->sk_rx_dst = NULL; 1395 } 1396 } 1397 tcp_rcv_established(sk, skb, tcp_hdr(skb), skb->len); 1398 return 0; 1399 } 1400 1401 if (tcp_checksum_complete(skb)) 1402 goto csum_err; 1403 1404 if (sk->sk_state == TCP_LISTEN) { 1405 struct sock *nsk = tcp_v4_cookie_check(sk, skb); 1406 1407 if (!nsk) 1408 goto discard; 1409 if (nsk != sk) { 1410 sock_rps_save_rxhash(nsk, skb); 1411 sk_mark_napi_id(nsk, skb); 1412 if (tcp_child_process(sk, nsk, skb)) { 1413 rsk = nsk; 1414 goto reset; 1415 } 1416 return 0; 1417 } 1418 } else 1419 sock_rps_save_rxhash(sk, skb); 1420 1421 if (tcp_rcv_state_process(sk, skb)) { 1422 rsk = sk; 1423 goto reset; 1424 } 1425 return 0; 1426 1427 reset: 1428 tcp_v4_send_reset(rsk, skb); 1429 discard: 1430 kfree_skb(skb); 1431 /* Be careful here. If this function gets more complicated and 1432 * gcc suffers from register pressure on the x86, sk (in %ebx) 1433 * might be destroyed here. This current version compiles correctly, 1434 * but you have been warned. 1435 */ 1436 return 0; 1437 1438 csum_err: 1439 TCP_INC_STATS(sock_net(sk), TCP_MIB_CSUMERRORS); 1440 TCP_INC_STATS(sock_net(sk), TCP_MIB_INERRS); 1441 goto discard; 1442 } 1443 EXPORT_SYMBOL(tcp_v4_do_rcv); 1444 1445 void tcp_v4_early_demux(struct sk_buff *skb) 1446 { 1447 const struct iphdr *iph; 1448 const struct tcphdr *th; 1449 struct sock *sk; 1450 1451 if (skb->pkt_type != PACKET_HOST) 1452 return; 1453 1454 if (!pskb_may_pull(skb, skb_transport_offset(skb) + sizeof(struct tcphdr))) 1455 return; 1456 1457 iph = ip_hdr(skb); 1458 th = tcp_hdr(skb); 1459 1460 if (th->doff < sizeof(struct tcphdr) / 4) 1461 return; 1462 1463 sk = __inet_lookup_established(dev_net(skb->dev), &tcp_hashinfo, 1464 iph->saddr, th->source, 1465 iph->daddr, ntohs(th->dest), 1466 skb->skb_iif); 1467 if (sk) { 1468 skb->sk = sk; 1469 skb->destructor = sock_edemux; 1470 if (sk_fullsock(sk)) { 1471 struct dst_entry *dst = READ_ONCE(sk->sk_rx_dst); 1472 1473 if (dst) 1474 dst = dst_check(dst, 0); 1475 if (dst && 1476 inet_sk(sk)->rx_dst_ifindex == skb->skb_iif) 1477 skb_dst_set_noref(skb, dst); 1478 } 1479 } 1480 } 1481 1482 /* Packet is added to VJ-style prequeue for processing in process 1483 * context, if a reader task is waiting. Apparently, this exciting 1484 * idea (VJ's mail "Re: query about TCP header on tcp-ip" of 07 Sep 93) 1485 * failed somewhere. Latency? Burstiness? Well, at least now we will 1486 * see, why it failed. 8)8) --ANK 1487 * 1488 */ 1489 bool tcp_prequeue(struct sock *sk, struct sk_buff *skb) 1490 { 1491 struct tcp_sock *tp = tcp_sk(sk); 1492 1493 if (sysctl_tcp_low_latency || !tp->ucopy.task) 1494 return false; 1495 1496 if (skb->len <= tcp_hdrlen(skb) && 1497 skb_queue_len(&tp->ucopy.prequeue) == 0) 1498 return false; 1499 1500 /* Before escaping RCU protected region, we need to take care of skb 1501 * dst. Prequeue is only enabled for established sockets. 1502 * For such sockets, we might need the skb dst only to set sk->sk_rx_dst 1503 * Instead of doing full sk_rx_dst validity here, let's perform 1504 * an optimistic check. 1505 */ 1506 if (likely(sk->sk_rx_dst)) 1507 skb_dst_drop(skb); 1508 else 1509 skb_dst_force_safe(skb); 1510 1511 __skb_queue_tail(&tp->ucopy.prequeue, skb); 1512 tp->ucopy.memory += skb->truesize; 1513 if (skb_queue_len(&tp->ucopy.prequeue) >= 32 || 1514 tp->ucopy.memory + atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf) { 1515 struct sk_buff *skb1; 1516 1517 BUG_ON(sock_owned_by_user(sk)); 1518 __NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPPREQUEUEDROPPED, 1519 skb_queue_len(&tp->ucopy.prequeue)); 1520 1521 while ((skb1 = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) 1522 sk_backlog_rcv(sk, skb1); 1523 1524 tp->ucopy.memory = 0; 1525 } else if (skb_queue_len(&tp->ucopy.prequeue) == 1) { 1526 wake_up_interruptible_sync_poll(sk_sleep(sk), 1527 POLLIN | POLLRDNORM | POLLRDBAND); 1528 if (!inet_csk_ack_scheduled(sk)) 1529 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 1530 (3 * tcp_rto_min(sk)) / 4, 1531 TCP_RTO_MAX); 1532 } 1533 return true; 1534 } 1535 EXPORT_SYMBOL(tcp_prequeue); 1536 1537 /* 1538 * From tcp_input.c 1539 */ 1540 1541 int tcp_v4_rcv(struct sk_buff *skb) 1542 { 1543 struct net *net = dev_net(skb->dev); 1544 const struct iphdr *iph; 1545 const struct tcphdr *th; 1546 bool refcounted; 1547 struct sock *sk; 1548 int ret; 1549 1550 if (skb->pkt_type != PACKET_HOST) 1551 goto discard_it; 1552 1553 /* Count it even if it's bad */ 1554 __TCP_INC_STATS(net, TCP_MIB_INSEGS); 1555 1556 if (!pskb_may_pull(skb, sizeof(struct tcphdr))) 1557 goto discard_it; 1558 1559 th = (const struct tcphdr *)skb->data; 1560 1561 if (unlikely(th->doff < sizeof(struct tcphdr) / 4)) 1562 goto bad_packet; 1563 if (!pskb_may_pull(skb, th->doff * 4)) 1564 goto discard_it; 1565 1566 /* An explanation is required here, I think. 1567 * Packet length and doff are validated by header prediction, 1568 * provided case of th->doff==0 is eliminated. 1569 * So, we defer the checks. */ 1570 1571 if (skb_checksum_init(skb, IPPROTO_TCP, inet_compute_pseudo)) 1572 goto csum_error; 1573 1574 th = (const struct tcphdr *)skb->data; 1575 iph = ip_hdr(skb); 1576 /* This is tricky : We move IPCB at its correct location into TCP_SKB_CB() 1577 * barrier() makes sure compiler wont play fool^Waliasing games. 1578 */ 1579 memmove(&TCP_SKB_CB(skb)->header.h4, IPCB(skb), 1580 sizeof(struct inet_skb_parm)); 1581 barrier(); 1582 1583 TCP_SKB_CB(skb)->seq = ntohl(th->seq); 1584 TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin + 1585 skb->len - th->doff * 4); 1586 TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq); 1587 TCP_SKB_CB(skb)->tcp_flags = tcp_flag_byte(th); 1588 TCP_SKB_CB(skb)->tcp_tw_isn = 0; 1589 TCP_SKB_CB(skb)->ip_dsfield = ipv4_get_dsfield(iph); 1590 TCP_SKB_CB(skb)->sacked = 0; 1591 1592 lookup: 1593 sk = __inet_lookup_skb(&tcp_hashinfo, skb, __tcp_hdrlen(th), th->source, 1594 th->dest, &refcounted); 1595 if (!sk) 1596 goto no_tcp_socket; 1597 1598 process: 1599 if (sk->sk_state == TCP_TIME_WAIT) 1600 goto do_time_wait; 1601 1602 if (sk->sk_state == TCP_NEW_SYN_RECV) { 1603 struct request_sock *req = inet_reqsk(sk); 1604 struct sock *nsk; 1605 1606 sk = req->rsk_listener; 1607 if (unlikely(tcp_v4_inbound_md5_hash(sk, skb))) { 1608 reqsk_put(req); 1609 goto discard_it; 1610 } 1611 if (unlikely(sk->sk_state != TCP_LISTEN)) { 1612 inet_csk_reqsk_queue_drop_and_put(sk, req); 1613 goto lookup; 1614 } 1615 /* We own a reference on the listener, increase it again 1616 * as we might lose it too soon. 1617 */ 1618 sock_hold(sk); 1619 refcounted = true; 1620 nsk = tcp_check_req(sk, skb, req, false); 1621 if (!nsk) { 1622 reqsk_put(req); 1623 goto discard_and_relse; 1624 } 1625 if (nsk == sk) { 1626 reqsk_put(req); 1627 } else if (tcp_child_process(sk, nsk, skb)) { 1628 tcp_v4_send_reset(nsk, skb); 1629 goto discard_and_relse; 1630 } else { 1631 sock_put(sk); 1632 return 0; 1633 } 1634 } 1635 if (unlikely(iph->ttl < inet_sk(sk)->min_ttl)) { 1636 __NET_INC_STATS(net, LINUX_MIB_TCPMINTTLDROP); 1637 goto discard_and_relse; 1638 } 1639 1640 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) 1641 goto discard_and_relse; 1642 1643 if (tcp_v4_inbound_md5_hash(sk, skb)) 1644 goto discard_and_relse; 1645 1646 nf_reset(skb); 1647 1648 if (sk_filter(sk, skb)) 1649 goto discard_and_relse; 1650 1651 skb->dev = NULL; 1652 1653 if (sk->sk_state == TCP_LISTEN) { 1654 ret = tcp_v4_do_rcv(sk, skb); 1655 goto put_and_return; 1656 } 1657 1658 sk_incoming_cpu_update(sk); 1659 1660 bh_lock_sock_nested(sk); 1661 tcp_segs_in(tcp_sk(sk), skb); 1662 ret = 0; 1663 if (!sock_owned_by_user(sk)) { 1664 if (!tcp_prequeue(sk, skb)) 1665 ret = tcp_v4_do_rcv(sk, skb); 1666 } else if (unlikely(sk_add_backlog(sk, skb, 1667 sk->sk_rcvbuf + sk->sk_sndbuf))) { 1668 bh_unlock_sock(sk); 1669 __NET_INC_STATS(net, LINUX_MIB_TCPBACKLOGDROP); 1670 goto discard_and_relse; 1671 } 1672 bh_unlock_sock(sk); 1673 1674 put_and_return: 1675 if (refcounted) 1676 sock_put(sk); 1677 1678 return ret; 1679 1680 no_tcp_socket: 1681 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) 1682 goto discard_it; 1683 1684 if (tcp_checksum_complete(skb)) { 1685 csum_error: 1686 __TCP_INC_STATS(net, TCP_MIB_CSUMERRORS); 1687 bad_packet: 1688 __TCP_INC_STATS(net, TCP_MIB_INERRS); 1689 } else { 1690 tcp_v4_send_reset(NULL, skb); 1691 } 1692 1693 discard_it: 1694 /* Discard frame. */ 1695 kfree_skb(skb); 1696 return 0; 1697 1698 discard_and_relse: 1699 sk_drops_add(sk, skb); 1700 if (refcounted) 1701 sock_put(sk); 1702 goto discard_it; 1703 1704 do_time_wait: 1705 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { 1706 inet_twsk_put(inet_twsk(sk)); 1707 goto discard_it; 1708 } 1709 1710 if (tcp_checksum_complete(skb)) { 1711 inet_twsk_put(inet_twsk(sk)); 1712 goto csum_error; 1713 } 1714 switch (tcp_timewait_state_process(inet_twsk(sk), skb, th)) { 1715 case TCP_TW_SYN: { 1716 struct sock *sk2 = inet_lookup_listener(dev_net(skb->dev), 1717 &tcp_hashinfo, skb, 1718 __tcp_hdrlen(th), 1719 iph->saddr, th->source, 1720 iph->daddr, th->dest, 1721 inet_iif(skb)); 1722 if (sk2) { 1723 inet_twsk_deschedule_put(inet_twsk(sk)); 1724 sk = sk2; 1725 refcounted = false; 1726 goto process; 1727 } 1728 /* Fall through to ACK */ 1729 } 1730 case TCP_TW_ACK: 1731 tcp_v4_timewait_ack(sk, skb); 1732 break; 1733 case TCP_TW_RST: 1734 tcp_v4_send_reset(sk, skb); 1735 inet_twsk_deschedule_put(inet_twsk(sk)); 1736 goto discard_it; 1737 case TCP_TW_SUCCESS:; 1738 } 1739 goto discard_it; 1740 } 1741 1742 static struct timewait_sock_ops tcp_timewait_sock_ops = { 1743 .twsk_obj_size = sizeof(struct tcp_timewait_sock), 1744 .twsk_unique = tcp_twsk_unique, 1745 .twsk_destructor= tcp_twsk_destructor, 1746 }; 1747 1748 void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb) 1749 { 1750 struct dst_entry *dst = skb_dst(skb); 1751 1752 if (dst && dst_hold_safe(dst)) { 1753 sk->sk_rx_dst = dst; 1754 inet_sk(sk)->rx_dst_ifindex = skb->skb_iif; 1755 } 1756 } 1757 EXPORT_SYMBOL(inet_sk_rx_dst_set); 1758 1759 const struct inet_connection_sock_af_ops ipv4_specific = { 1760 .queue_xmit = ip_queue_xmit, 1761 .send_check = tcp_v4_send_check, 1762 .rebuild_header = inet_sk_rebuild_header, 1763 .sk_rx_dst_set = inet_sk_rx_dst_set, 1764 .conn_request = tcp_v4_conn_request, 1765 .syn_recv_sock = tcp_v4_syn_recv_sock, 1766 .net_header_len = sizeof(struct iphdr), 1767 .setsockopt = ip_setsockopt, 1768 .getsockopt = ip_getsockopt, 1769 .addr2sockaddr = inet_csk_addr2sockaddr, 1770 .sockaddr_len = sizeof(struct sockaddr_in), 1771 .bind_conflict = inet_csk_bind_conflict, 1772 #ifdef CONFIG_COMPAT 1773 .compat_setsockopt = compat_ip_setsockopt, 1774 .compat_getsockopt = compat_ip_getsockopt, 1775 #endif 1776 .mtu_reduced = tcp_v4_mtu_reduced, 1777 }; 1778 EXPORT_SYMBOL(ipv4_specific); 1779 1780 #ifdef CONFIG_TCP_MD5SIG 1781 static const struct tcp_sock_af_ops tcp_sock_ipv4_specific = { 1782 .md5_lookup = tcp_v4_md5_lookup, 1783 .calc_md5_hash = tcp_v4_md5_hash_skb, 1784 .md5_parse = tcp_v4_parse_md5_keys, 1785 }; 1786 #endif 1787 1788 /* NOTE: A lot of things set to zero explicitly by call to 1789 * sk_alloc() so need not be done here. 1790 */ 1791 static int tcp_v4_init_sock(struct sock *sk) 1792 { 1793 struct inet_connection_sock *icsk = inet_csk(sk); 1794 1795 tcp_init_sock(sk); 1796 1797 icsk->icsk_af_ops = &ipv4_specific; 1798 1799 #ifdef CONFIG_TCP_MD5SIG 1800 tcp_sk(sk)->af_specific = &tcp_sock_ipv4_specific; 1801 #endif 1802 1803 return 0; 1804 } 1805 1806 void tcp_v4_destroy_sock(struct sock *sk) 1807 { 1808 struct tcp_sock *tp = tcp_sk(sk); 1809 1810 tcp_clear_xmit_timers(sk); 1811 1812 tcp_cleanup_congestion_control(sk); 1813 1814 /* Cleanup up the write buffer. */ 1815 tcp_write_queue_purge(sk); 1816 1817 /* Cleans up our, hopefully empty, out_of_order_queue. */ 1818 __skb_queue_purge(&tp->out_of_order_queue); 1819 1820 #ifdef CONFIG_TCP_MD5SIG 1821 /* Clean up the MD5 key list, if any */ 1822 if (tp->md5sig_info) { 1823 tcp_clear_md5_list(sk); 1824 kfree_rcu(tp->md5sig_info, rcu); 1825 tp->md5sig_info = NULL; 1826 } 1827 #endif 1828 1829 /* Clean prequeue, it must be empty really */ 1830 __skb_queue_purge(&tp->ucopy.prequeue); 1831 1832 /* Clean up a referenced TCP bind bucket. */ 1833 if (inet_csk(sk)->icsk_bind_hash) 1834 inet_put_port(sk); 1835 1836 BUG_ON(tp->fastopen_rsk); 1837 1838 /* If socket is aborted during connect operation */ 1839 tcp_free_fastopen_req(tp); 1840 tcp_saved_syn_free(tp); 1841 1842 local_bh_disable(); 1843 sk_sockets_allocated_dec(sk); 1844 local_bh_enable(); 1845 1846 if (mem_cgroup_sockets_enabled && sk->sk_memcg) 1847 sock_release_memcg(sk); 1848 } 1849 EXPORT_SYMBOL(tcp_v4_destroy_sock); 1850 1851 #ifdef CONFIG_PROC_FS 1852 /* Proc filesystem TCP sock list dumping. */ 1853 1854 /* 1855 * Get next listener socket follow cur. If cur is NULL, get first socket 1856 * starting from bucket given in st->bucket; when st->bucket is zero the 1857 * very first socket in the hash table is returned. 1858 */ 1859 static void *listening_get_next(struct seq_file *seq, void *cur) 1860 { 1861 struct tcp_iter_state *st = seq->private; 1862 struct net *net = seq_file_net(seq); 1863 struct inet_listen_hashbucket *ilb; 1864 struct inet_connection_sock *icsk; 1865 struct sock *sk = cur; 1866 1867 if (!sk) { 1868 get_head: 1869 ilb = &tcp_hashinfo.listening_hash[st->bucket]; 1870 spin_lock_bh(&ilb->lock); 1871 sk = sk_head(&ilb->head); 1872 st->offset = 0; 1873 goto get_sk; 1874 } 1875 ilb = &tcp_hashinfo.listening_hash[st->bucket]; 1876 ++st->num; 1877 ++st->offset; 1878 1879 sk = sk_next(sk); 1880 get_sk: 1881 sk_for_each_from(sk) { 1882 if (!net_eq(sock_net(sk), net)) 1883 continue; 1884 if (sk->sk_family == st->family) 1885 return sk; 1886 icsk = inet_csk(sk); 1887 } 1888 spin_unlock_bh(&ilb->lock); 1889 st->offset = 0; 1890 if (++st->bucket < INET_LHTABLE_SIZE) 1891 goto get_head; 1892 return NULL; 1893 } 1894 1895 static void *listening_get_idx(struct seq_file *seq, loff_t *pos) 1896 { 1897 struct tcp_iter_state *st = seq->private; 1898 void *rc; 1899 1900 st->bucket = 0; 1901 st->offset = 0; 1902 rc = listening_get_next(seq, NULL); 1903 1904 while (rc && *pos) { 1905 rc = listening_get_next(seq, rc); 1906 --*pos; 1907 } 1908 return rc; 1909 } 1910 1911 static inline bool empty_bucket(const struct tcp_iter_state *st) 1912 { 1913 return hlist_nulls_empty(&tcp_hashinfo.ehash[st->bucket].chain); 1914 } 1915 1916 /* 1917 * Get first established socket starting from bucket given in st->bucket. 1918 * If st->bucket is zero, the very first socket in the hash is returned. 1919 */ 1920 static void *established_get_first(struct seq_file *seq) 1921 { 1922 struct tcp_iter_state *st = seq->private; 1923 struct net *net = seq_file_net(seq); 1924 void *rc = NULL; 1925 1926 st->offset = 0; 1927 for (; st->bucket <= tcp_hashinfo.ehash_mask; ++st->bucket) { 1928 struct sock *sk; 1929 struct hlist_nulls_node *node; 1930 spinlock_t *lock = inet_ehash_lockp(&tcp_hashinfo, st->bucket); 1931 1932 /* Lockless fast path for the common case of empty buckets */ 1933 if (empty_bucket(st)) 1934 continue; 1935 1936 spin_lock_bh(lock); 1937 sk_nulls_for_each(sk, node, &tcp_hashinfo.ehash[st->bucket].chain) { 1938 if (sk->sk_family != st->family || 1939 !net_eq(sock_net(sk), net)) { 1940 continue; 1941 } 1942 rc = sk; 1943 goto out; 1944 } 1945 spin_unlock_bh(lock); 1946 } 1947 out: 1948 return rc; 1949 } 1950 1951 static void *established_get_next(struct seq_file *seq, void *cur) 1952 { 1953 struct sock *sk = cur; 1954 struct hlist_nulls_node *node; 1955 struct tcp_iter_state *st = seq->private; 1956 struct net *net = seq_file_net(seq); 1957 1958 ++st->num; 1959 ++st->offset; 1960 1961 sk = sk_nulls_next(sk); 1962 1963 sk_nulls_for_each_from(sk, node) { 1964 if (sk->sk_family == st->family && net_eq(sock_net(sk), net)) 1965 return sk; 1966 } 1967 1968 spin_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket)); 1969 ++st->bucket; 1970 return established_get_first(seq); 1971 } 1972 1973 static void *established_get_idx(struct seq_file *seq, loff_t pos) 1974 { 1975 struct tcp_iter_state *st = seq->private; 1976 void *rc; 1977 1978 st->bucket = 0; 1979 rc = established_get_first(seq); 1980 1981 while (rc && pos) { 1982 rc = established_get_next(seq, rc); 1983 --pos; 1984 } 1985 return rc; 1986 } 1987 1988 static void *tcp_get_idx(struct seq_file *seq, loff_t pos) 1989 { 1990 void *rc; 1991 struct tcp_iter_state *st = seq->private; 1992 1993 st->state = TCP_SEQ_STATE_LISTENING; 1994 rc = listening_get_idx(seq, &pos); 1995 1996 if (!rc) { 1997 st->state = TCP_SEQ_STATE_ESTABLISHED; 1998 rc = established_get_idx(seq, pos); 1999 } 2000 2001 return rc; 2002 } 2003 2004 static void *tcp_seek_last_pos(struct seq_file *seq) 2005 { 2006 struct tcp_iter_state *st = seq->private; 2007 int offset = st->offset; 2008 int orig_num = st->num; 2009 void *rc = NULL; 2010 2011 switch (st->state) { 2012 case TCP_SEQ_STATE_LISTENING: 2013 if (st->bucket >= INET_LHTABLE_SIZE) 2014 break; 2015 st->state = TCP_SEQ_STATE_LISTENING; 2016 rc = listening_get_next(seq, NULL); 2017 while (offset-- && rc) 2018 rc = listening_get_next(seq, rc); 2019 if (rc) 2020 break; 2021 st->bucket = 0; 2022 st->state = TCP_SEQ_STATE_ESTABLISHED; 2023 /* Fallthrough */ 2024 case TCP_SEQ_STATE_ESTABLISHED: 2025 if (st->bucket > tcp_hashinfo.ehash_mask) 2026 break; 2027 rc = established_get_first(seq); 2028 while (offset-- && rc) 2029 rc = established_get_next(seq, rc); 2030 } 2031 2032 st->num = orig_num; 2033 2034 return rc; 2035 } 2036 2037 static void *tcp_seq_start(struct seq_file *seq, loff_t *pos) 2038 { 2039 struct tcp_iter_state *st = seq->private; 2040 void *rc; 2041 2042 if (*pos && *pos == st->last_pos) { 2043 rc = tcp_seek_last_pos(seq); 2044 if (rc) 2045 goto out; 2046 } 2047 2048 st->state = TCP_SEQ_STATE_LISTENING; 2049 st->num = 0; 2050 st->bucket = 0; 2051 st->offset = 0; 2052 rc = *pos ? tcp_get_idx(seq, *pos - 1) : SEQ_START_TOKEN; 2053 2054 out: 2055 st->last_pos = *pos; 2056 return rc; 2057 } 2058 2059 static void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos) 2060 { 2061 struct tcp_iter_state *st = seq->private; 2062 void *rc = NULL; 2063 2064 if (v == SEQ_START_TOKEN) { 2065 rc = tcp_get_idx(seq, 0); 2066 goto out; 2067 } 2068 2069 switch (st->state) { 2070 case TCP_SEQ_STATE_LISTENING: 2071 rc = listening_get_next(seq, v); 2072 if (!rc) { 2073 st->state = TCP_SEQ_STATE_ESTABLISHED; 2074 st->bucket = 0; 2075 st->offset = 0; 2076 rc = established_get_first(seq); 2077 } 2078 break; 2079 case TCP_SEQ_STATE_ESTABLISHED: 2080 rc = established_get_next(seq, v); 2081 break; 2082 } 2083 out: 2084 ++*pos; 2085 st->last_pos = *pos; 2086 return rc; 2087 } 2088 2089 static void tcp_seq_stop(struct seq_file *seq, void *v) 2090 { 2091 struct tcp_iter_state *st = seq->private; 2092 2093 switch (st->state) { 2094 case TCP_SEQ_STATE_LISTENING: 2095 if (v != SEQ_START_TOKEN) 2096 spin_unlock_bh(&tcp_hashinfo.listening_hash[st->bucket].lock); 2097 break; 2098 case TCP_SEQ_STATE_ESTABLISHED: 2099 if (v) 2100 spin_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket)); 2101 break; 2102 } 2103 } 2104 2105 int tcp_seq_open(struct inode *inode, struct file *file) 2106 { 2107 struct tcp_seq_afinfo *afinfo = PDE_DATA(inode); 2108 struct tcp_iter_state *s; 2109 int err; 2110 2111 err = seq_open_net(inode, file, &afinfo->seq_ops, 2112 sizeof(struct tcp_iter_state)); 2113 if (err < 0) 2114 return err; 2115 2116 s = ((struct seq_file *)file->private_data)->private; 2117 s->family = afinfo->family; 2118 s->last_pos = 0; 2119 return 0; 2120 } 2121 EXPORT_SYMBOL(tcp_seq_open); 2122 2123 int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo) 2124 { 2125 int rc = 0; 2126 struct proc_dir_entry *p; 2127 2128 afinfo->seq_ops.start = tcp_seq_start; 2129 afinfo->seq_ops.next = tcp_seq_next; 2130 afinfo->seq_ops.stop = tcp_seq_stop; 2131 2132 p = proc_create_data(afinfo->name, S_IRUGO, net->proc_net, 2133 afinfo->seq_fops, afinfo); 2134 if (!p) 2135 rc = -ENOMEM; 2136 return rc; 2137 } 2138 EXPORT_SYMBOL(tcp_proc_register); 2139 2140 void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo) 2141 { 2142 remove_proc_entry(afinfo->name, net->proc_net); 2143 } 2144 EXPORT_SYMBOL(tcp_proc_unregister); 2145 2146 static void get_openreq4(const struct request_sock *req, 2147 struct seq_file *f, int i) 2148 { 2149 const struct inet_request_sock *ireq = inet_rsk(req); 2150 long delta = req->rsk_timer.expires - jiffies; 2151 2152 seq_printf(f, "%4d: %08X:%04X %08X:%04X" 2153 " %02X %08X:%08X %02X:%08lX %08X %5u %8d %u %d %pK", 2154 i, 2155 ireq->ir_loc_addr, 2156 ireq->ir_num, 2157 ireq->ir_rmt_addr, 2158 ntohs(ireq->ir_rmt_port), 2159 TCP_SYN_RECV, 2160 0, 0, /* could print option size, but that is af dependent. */ 2161 1, /* timers active (only the expire timer) */ 2162 jiffies_delta_to_clock_t(delta), 2163 req->num_timeout, 2164 from_kuid_munged(seq_user_ns(f), 2165 sock_i_uid(req->rsk_listener)), 2166 0, /* non standard timer */ 2167 0, /* open_requests have no inode */ 2168 0, 2169 req); 2170 } 2171 2172 static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i) 2173 { 2174 int timer_active; 2175 unsigned long timer_expires; 2176 const struct tcp_sock *tp = tcp_sk(sk); 2177 const struct inet_connection_sock *icsk = inet_csk(sk); 2178 const struct inet_sock *inet = inet_sk(sk); 2179 const struct fastopen_queue *fastopenq = &icsk->icsk_accept_queue.fastopenq; 2180 __be32 dest = inet->inet_daddr; 2181 __be32 src = inet->inet_rcv_saddr; 2182 __u16 destp = ntohs(inet->inet_dport); 2183 __u16 srcp = ntohs(inet->inet_sport); 2184 int rx_queue; 2185 int state; 2186 2187 if (icsk->icsk_pending == ICSK_TIME_RETRANS || 2188 icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS || 2189 icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) { 2190 timer_active = 1; 2191 timer_expires = icsk->icsk_timeout; 2192 } else if (icsk->icsk_pending == ICSK_TIME_PROBE0) { 2193 timer_active = 4; 2194 timer_expires = icsk->icsk_timeout; 2195 } else if (timer_pending(&sk->sk_timer)) { 2196 timer_active = 2; 2197 timer_expires = sk->sk_timer.expires; 2198 } else { 2199 timer_active = 0; 2200 timer_expires = jiffies; 2201 } 2202 2203 state = sk_state_load(sk); 2204 if (state == TCP_LISTEN) 2205 rx_queue = sk->sk_ack_backlog; 2206 else 2207 /* Because we don't lock the socket, 2208 * we might find a transient negative value. 2209 */ 2210 rx_queue = max_t(int, tp->rcv_nxt - tp->copied_seq, 0); 2211 2212 seq_printf(f, "%4d: %08X:%04X %08X:%04X %02X %08X:%08X %02X:%08lX " 2213 "%08X %5u %8d %lu %d %pK %lu %lu %u %u %d", 2214 i, src, srcp, dest, destp, state, 2215 tp->write_seq - tp->snd_una, 2216 rx_queue, 2217 timer_active, 2218 jiffies_delta_to_clock_t(timer_expires - jiffies), 2219 icsk->icsk_retransmits, 2220 from_kuid_munged(seq_user_ns(f), sock_i_uid(sk)), 2221 icsk->icsk_probes_out, 2222 sock_i_ino(sk), 2223 atomic_read(&sk->sk_refcnt), sk, 2224 jiffies_to_clock_t(icsk->icsk_rto), 2225 jiffies_to_clock_t(icsk->icsk_ack.ato), 2226 (icsk->icsk_ack.quick << 1) | icsk->icsk_ack.pingpong, 2227 tp->snd_cwnd, 2228 state == TCP_LISTEN ? 2229 fastopenq->max_qlen : 2230 (tcp_in_initial_slowstart(tp) ? -1 : tp->snd_ssthresh)); 2231 } 2232 2233 static void get_timewait4_sock(const struct inet_timewait_sock *tw, 2234 struct seq_file *f, int i) 2235 { 2236 long delta = tw->tw_timer.expires - jiffies; 2237 __be32 dest, src; 2238 __u16 destp, srcp; 2239 2240 dest = tw->tw_daddr; 2241 src = tw->tw_rcv_saddr; 2242 destp = ntohs(tw->tw_dport); 2243 srcp = ntohs(tw->tw_sport); 2244 2245 seq_printf(f, "%4d: %08X:%04X %08X:%04X" 2246 " %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %pK", 2247 i, src, srcp, dest, destp, tw->tw_substate, 0, 0, 2248 3, jiffies_delta_to_clock_t(delta), 0, 0, 0, 0, 2249 atomic_read(&tw->tw_refcnt), tw); 2250 } 2251 2252 #define TMPSZ 150 2253 2254 static int tcp4_seq_show(struct seq_file *seq, void *v) 2255 { 2256 struct tcp_iter_state *st; 2257 struct sock *sk = v; 2258 2259 seq_setwidth(seq, TMPSZ - 1); 2260 if (v == SEQ_START_TOKEN) { 2261 seq_puts(seq, " sl local_address rem_address st tx_queue " 2262 "rx_queue tr tm->when retrnsmt uid timeout " 2263 "inode"); 2264 goto out; 2265 } 2266 st = seq->private; 2267 2268 if (sk->sk_state == TCP_TIME_WAIT) 2269 get_timewait4_sock(v, seq, st->num); 2270 else if (sk->sk_state == TCP_NEW_SYN_RECV) 2271 get_openreq4(v, seq, st->num); 2272 else 2273 get_tcp4_sock(v, seq, st->num); 2274 out: 2275 seq_pad(seq, '\n'); 2276 return 0; 2277 } 2278 2279 static const struct file_operations tcp_afinfo_seq_fops = { 2280 .owner = THIS_MODULE, 2281 .open = tcp_seq_open, 2282 .read = seq_read, 2283 .llseek = seq_lseek, 2284 .release = seq_release_net 2285 }; 2286 2287 static struct tcp_seq_afinfo tcp4_seq_afinfo = { 2288 .name = "tcp", 2289 .family = AF_INET, 2290 .seq_fops = &tcp_afinfo_seq_fops, 2291 .seq_ops = { 2292 .show = tcp4_seq_show, 2293 }, 2294 }; 2295 2296 static int __net_init tcp4_proc_init_net(struct net *net) 2297 { 2298 return tcp_proc_register(net, &tcp4_seq_afinfo); 2299 } 2300 2301 static void __net_exit tcp4_proc_exit_net(struct net *net) 2302 { 2303 tcp_proc_unregister(net, &tcp4_seq_afinfo); 2304 } 2305 2306 static struct pernet_operations tcp4_net_ops = { 2307 .init = tcp4_proc_init_net, 2308 .exit = tcp4_proc_exit_net, 2309 }; 2310 2311 int __init tcp4_proc_init(void) 2312 { 2313 return register_pernet_subsys(&tcp4_net_ops); 2314 } 2315 2316 void tcp4_proc_exit(void) 2317 { 2318 unregister_pernet_subsys(&tcp4_net_ops); 2319 } 2320 #endif /* CONFIG_PROC_FS */ 2321 2322 struct proto tcp_prot = { 2323 .name = "TCP", 2324 .owner = THIS_MODULE, 2325 .close = tcp_close, 2326 .connect = tcp_v4_connect, 2327 .disconnect = tcp_disconnect, 2328 .accept = inet_csk_accept, 2329 .ioctl = tcp_ioctl, 2330 .init = tcp_v4_init_sock, 2331 .destroy = tcp_v4_destroy_sock, 2332 .shutdown = tcp_shutdown, 2333 .setsockopt = tcp_setsockopt, 2334 .getsockopt = tcp_getsockopt, 2335 .recvmsg = tcp_recvmsg, 2336 .sendmsg = tcp_sendmsg, 2337 .sendpage = tcp_sendpage, 2338 .backlog_rcv = tcp_v4_do_rcv, 2339 .release_cb = tcp_release_cb, 2340 .hash = inet_hash, 2341 .unhash = inet_unhash, 2342 .get_port = inet_csk_get_port, 2343 .enter_memory_pressure = tcp_enter_memory_pressure, 2344 .stream_memory_free = tcp_stream_memory_free, 2345 .sockets_allocated = &tcp_sockets_allocated, 2346 .orphan_count = &tcp_orphan_count, 2347 .memory_allocated = &tcp_memory_allocated, 2348 .memory_pressure = &tcp_memory_pressure, 2349 .sysctl_mem = sysctl_tcp_mem, 2350 .sysctl_wmem = sysctl_tcp_wmem, 2351 .sysctl_rmem = sysctl_tcp_rmem, 2352 .max_header = MAX_TCP_HEADER, 2353 .obj_size = sizeof(struct tcp_sock), 2354 .slab_flags = SLAB_DESTROY_BY_RCU, 2355 .twsk_prot = &tcp_timewait_sock_ops, 2356 .rsk_prot = &tcp_request_sock_ops, 2357 .h.hashinfo = &tcp_hashinfo, 2358 .no_autobind = true, 2359 #ifdef CONFIG_COMPAT 2360 .compat_setsockopt = compat_tcp_setsockopt, 2361 .compat_getsockopt = compat_tcp_getsockopt, 2362 #endif 2363 .diag_destroy = tcp_abort, 2364 }; 2365 EXPORT_SYMBOL(tcp_prot); 2366 2367 static void __net_exit tcp_sk_exit(struct net *net) 2368 { 2369 int cpu; 2370 2371 for_each_possible_cpu(cpu) 2372 inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.tcp_sk, cpu)); 2373 free_percpu(net->ipv4.tcp_sk); 2374 } 2375 2376 static int __net_init tcp_sk_init(struct net *net) 2377 { 2378 int res, cpu; 2379 2380 net->ipv4.tcp_sk = alloc_percpu(struct sock *); 2381 if (!net->ipv4.tcp_sk) 2382 return -ENOMEM; 2383 2384 for_each_possible_cpu(cpu) { 2385 struct sock *sk; 2386 2387 res = inet_ctl_sock_create(&sk, PF_INET, SOCK_RAW, 2388 IPPROTO_TCP, net); 2389 if (res) 2390 goto fail; 2391 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE); 2392 *per_cpu_ptr(net->ipv4.tcp_sk, cpu) = sk; 2393 } 2394 2395 net->ipv4.sysctl_tcp_ecn = 2; 2396 net->ipv4.sysctl_tcp_ecn_fallback = 1; 2397 2398 net->ipv4.sysctl_tcp_base_mss = TCP_BASE_MSS; 2399 net->ipv4.sysctl_tcp_probe_threshold = TCP_PROBE_THRESHOLD; 2400 net->ipv4.sysctl_tcp_probe_interval = TCP_PROBE_INTERVAL; 2401 2402 net->ipv4.sysctl_tcp_keepalive_time = TCP_KEEPALIVE_TIME; 2403 net->ipv4.sysctl_tcp_keepalive_probes = TCP_KEEPALIVE_PROBES; 2404 net->ipv4.sysctl_tcp_keepalive_intvl = TCP_KEEPALIVE_INTVL; 2405 2406 net->ipv4.sysctl_tcp_syn_retries = TCP_SYN_RETRIES; 2407 net->ipv4.sysctl_tcp_synack_retries = TCP_SYNACK_RETRIES; 2408 net->ipv4.sysctl_tcp_syncookies = 1; 2409 net->ipv4.sysctl_tcp_reordering = TCP_FASTRETRANS_THRESH; 2410 net->ipv4.sysctl_tcp_retries1 = TCP_RETR1; 2411 net->ipv4.sysctl_tcp_retries2 = TCP_RETR2; 2412 net->ipv4.sysctl_tcp_orphan_retries = 0; 2413 net->ipv4.sysctl_tcp_fin_timeout = TCP_FIN_TIMEOUT; 2414 net->ipv4.sysctl_tcp_notsent_lowat = UINT_MAX; 2415 2416 return 0; 2417 fail: 2418 tcp_sk_exit(net); 2419 2420 return res; 2421 } 2422 2423 static void __net_exit tcp_sk_exit_batch(struct list_head *net_exit_list) 2424 { 2425 inet_twsk_purge(&tcp_hashinfo, &tcp_death_row, AF_INET); 2426 } 2427 2428 static struct pernet_operations __net_initdata tcp_sk_ops = { 2429 .init = tcp_sk_init, 2430 .exit = tcp_sk_exit, 2431 .exit_batch = tcp_sk_exit_batch, 2432 }; 2433 2434 void __init tcp_v4_init(void) 2435 { 2436 inet_hashinfo_init(&tcp_hashinfo); 2437 if (register_pernet_subsys(&tcp_sk_ops)) 2438 panic("Failed to create the TCP control socket.\n"); 2439 } 2440