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_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5FAILURE); 1179 net_info_ratelimited("MD5 Hash failed for (%pI4, %d)->(%pI4, %d)%s\n", 1180 &iph->saddr, ntohs(th->source), 1181 &iph->daddr, ntohs(th->dest), 1182 genhash ? " tcp_v4_calc_md5_hash failed" 1183 : ""); 1184 return true; 1185 } 1186 return false; 1187 #endif 1188 return false; 1189 } 1190 1191 static void tcp_v4_init_req(struct request_sock *req, 1192 const struct sock *sk_listener, 1193 struct sk_buff *skb) 1194 { 1195 struct inet_request_sock *ireq = inet_rsk(req); 1196 1197 sk_rcv_saddr_set(req_to_sk(req), ip_hdr(skb)->daddr); 1198 sk_daddr_set(req_to_sk(req), ip_hdr(skb)->saddr); 1199 ireq->no_srccheck = inet_sk(sk_listener)->transparent; 1200 ireq->opt = tcp_v4_save_options(skb); 1201 } 1202 1203 static struct dst_entry *tcp_v4_route_req(const struct sock *sk, 1204 struct flowi *fl, 1205 const struct request_sock *req, 1206 bool *strict) 1207 { 1208 struct dst_entry *dst = inet_csk_route_req(sk, &fl->u.ip4, req); 1209 1210 if (strict) { 1211 if (fl->u.ip4.daddr == inet_rsk(req)->ir_rmt_addr) 1212 *strict = true; 1213 else 1214 *strict = false; 1215 } 1216 1217 return dst; 1218 } 1219 1220 struct request_sock_ops tcp_request_sock_ops __read_mostly = { 1221 .family = PF_INET, 1222 .obj_size = sizeof(struct tcp_request_sock), 1223 .rtx_syn_ack = tcp_rtx_synack, 1224 .send_ack = tcp_v4_reqsk_send_ack, 1225 .destructor = tcp_v4_reqsk_destructor, 1226 .send_reset = tcp_v4_send_reset, 1227 .syn_ack_timeout = tcp_syn_ack_timeout, 1228 }; 1229 1230 static const struct tcp_request_sock_ops tcp_request_sock_ipv4_ops = { 1231 .mss_clamp = TCP_MSS_DEFAULT, 1232 #ifdef CONFIG_TCP_MD5SIG 1233 .req_md5_lookup = tcp_v4_md5_lookup, 1234 .calc_md5_hash = tcp_v4_md5_hash_skb, 1235 #endif 1236 .init_req = tcp_v4_init_req, 1237 #ifdef CONFIG_SYN_COOKIES 1238 .cookie_init_seq = cookie_v4_init_sequence, 1239 #endif 1240 .route_req = tcp_v4_route_req, 1241 .init_seq = tcp_v4_init_sequence, 1242 .send_synack = tcp_v4_send_synack, 1243 }; 1244 1245 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb) 1246 { 1247 /* Never answer to SYNs send to broadcast or multicast */ 1248 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 1249 goto drop; 1250 1251 return tcp_conn_request(&tcp_request_sock_ops, 1252 &tcp_request_sock_ipv4_ops, sk, skb); 1253 1254 drop: 1255 tcp_listendrop(sk); 1256 return 0; 1257 } 1258 EXPORT_SYMBOL(tcp_v4_conn_request); 1259 1260 1261 /* 1262 * The three way handshake has completed - we got a valid synack - 1263 * now create the new socket. 1264 */ 1265 struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb, 1266 struct request_sock *req, 1267 struct dst_entry *dst, 1268 struct request_sock *req_unhash, 1269 bool *own_req) 1270 { 1271 struct inet_request_sock *ireq; 1272 struct inet_sock *newinet; 1273 struct tcp_sock *newtp; 1274 struct sock *newsk; 1275 #ifdef CONFIG_TCP_MD5SIG 1276 struct tcp_md5sig_key *key; 1277 #endif 1278 struct ip_options_rcu *inet_opt; 1279 1280 if (sk_acceptq_is_full(sk)) 1281 goto exit_overflow; 1282 1283 newsk = tcp_create_openreq_child(sk, req, skb); 1284 if (!newsk) 1285 goto exit_nonewsk; 1286 1287 newsk->sk_gso_type = SKB_GSO_TCPV4; 1288 inet_sk_rx_dst_set(newsk, skb); 1289 1290 newtp = tcp_sk(newsk); 1291 newinet = inet_sk(newsk); 1292 ireq = inet_rsk(req); 1293 sk_daddr_set(newsk, ireq->ir_rmt_addr); 1294 sk_rcv_saddr_set(newsk, ireq->ir_loc_addr); 1295 newsk->sk_bound_dev_if = ireq->ir_iif; 1296 newinet->inet_saddr = ireq->ir_loc_addr; 1297 inet_opt = ireq->opt; 1298 rcu_assign_pointer(newinet->inet_opt, inet_opt); 1299 ireq->opt = NULL; 1300 newinet->mc_index = inet_iif(skb); 1301 newinet->mc_ttl = ip_hdr(skb)->ttl; 1302 newinet->rcv_tos = ip_hdr(skb)->tos; 1303 inet_csk(newsk)->icsk_ext_hdr_len = 0; 1304 if (inet_opt) 1305 inet_csk(newsk)->icsk_ext_hdr_len = inet_opt->opt.optlen; 1306 newinet->inet_id = newtp->write_seq ^ jiffies; 1307 1308 if (!dst) { 1309 dst = inet_csk_route_child_sock(sk, newsk, req); 1310 if (!dst) 1311 goto put_and_exit; 1312 } else { 1313 /* syncookie case : see end of cookie_v4_check() */ 1314 } 1315 sk_setup_caps(newsk, dst); 1316 1317 tcp_ca_openreq_child(newsk, dst); 1318 1319 tcp_sync_mss(newsk, dst_mtu(dst)); 1320 newtp->advmss = dst_metric_advmss(dst); 1321 if (tcp_sk(sk)->rx_opt.user_mss && 1322 tcp_sk(sk)->rx_opt.user_mss < newtp->advmss) 1323 newtp->advmss = tcp_sk(sk)->rx_opt.user_mss; 1324 1325 tcp_initialize_rcv_mss(newsk); 1326 1327 #ifdef CONFIG_TCP_MD5SIG 1328 /* Copy over the MD5 key from the original socket */ 1329 key = tcp_md5_do_lookup(sk, (union tcp_md5_addr *)&newinet->inet_daddr, 1330 AF_INET); 1331 if (key) { 1332 /* 1333 * We're using one, so create a matching key 1334 * on the newsk structure. If we fail to get 1335 * memory, then we end up not copying the key 1336 * across. Shucks. 1337 */ 1338 tcp_md5_do_add(newsk, (union tcp_md5_addr *)&newinet->inet_daddr, 1339 AF_INET, key->key, key->keylen, GFP_ATOMIC); 1340 sk_nocaps_add(newsk, NETIF_F_GSO_MASK); 1341 } 1342 #endif 1343 1344 if (__inet_inherit_port(sk, newsk) < 0) 1345 goto put_and_exit; 1346 *own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash)); 1347 if (*own_req) 1348 tcp_move_syn(newtp, req); 1349 1350 return newsk; 1351 1352 exit_overflow: 1353 NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS); 1354 exit_nonewsk: 1355 dst_release(dst); 1356 exit: 1357 tcp_listendrop(sk); 1358 return NULL; 1359 put_and_exit: 1360 inet_csk_prepare_forced_close(newsk); 1361 tcp_done(newsk); 1362 goto exit; 1363 } 1364 EXPORT_SYMBOL(tcp_v4_syn_recv_sock); 1365 1366 static struct sock *tcp_v4_cookie_check(struct sock *sk, struct sk_buff *skb) 1367 { 1368 #ifdef CONFIG_SYN_COOKIES 1369 const struct tcphdr *th = tcp_hdr(skb); 1370 1371 if (!th->syn) 1372 sk = cookie_v4_check(sk, skb); 1373 #endif 1374 return sk; 1375 } 1376 1377 /* The socket must have it's spinlock held when we get 1378 * here, unless it is a TCP_LISTEN socket. 1379 * 1380 * We have a potential double-lock case here, so even when 1381 * doing backlog processing we use the BH locking scheme. 1382 * This is because we cannot sleep with the original spinlock 1383 * held. 1384 */ 1385 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb) 1386 { 1387 struct sock *rsk; 1388 1389 if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */ 1390 struct dst_entry *dst = sk->sk_rx_dst; 1391 1392 sock_rps_save_rxhash(sk, skb); 1393 sk_mark_napi_id(sk, skb); 1394 if (dst) { 1395 if (inet_sk(sk)->rx_dst_ifindex != skb->skb_iif || 1396 !dst->ops->check(dst, 0)) { 1397 dst_release(dst); 1398 sk->sk_rx_dst = NULL; 1399 } 1400 } 1401 tcp_rcv_established(sk, skb, tcp_hdr(skb), skb->len); 1402 return 0; 1403 } 1404 1405 if (tcp_checksum_complete(skb)) 1406 goto csum_err; 1407 1408 if (sk->sk_state == TCP_LISTEN) { 1409 struct sock *nsk = tcp_v4_cookie_check(sk, skb); 1410 1411 if (!nsk) 1412 goto discard; 1413 if (nsk != sk) { 1414 sock_rps_save_rxhash(nsk, skb); 1415 sk_mark_napi_id(nsk, skb); 1416 if (tcp_child_process(sk, nsk, skb)) { 1417 rsk = nsk; 1418 goto reset; 1419 } 1420 return 0; 1421 } 1422 } else 1423 sock_rps_save_rxhash(sk, skb); 1424 1425 if (tcp_rcv_state_process(sk, skb)) { 1426 rsk = sk; 1427 goto reset; 1428 } 1429 return 0; 1430 1431 reset: 1432 tcp_v4_send_reset(rsk, skb); 1433 discard: 1434 kfree_skb(skb); 1435 /* Be careful here. If this function gets more complicated and 1436 * gcc suffers from register pressure on the x86, sk (in %ebx) 1437 * might be destroyed here. This current version compiles correctly, 1438 * but you have been warned. 1439 */ 1440 return 0; 1441 1442 csum_err: 1443 TCP_INC_STATS(sock_net(sk), TCP_MIB_CSUMERRORS); 1444 TCP_INC_STATS(sock_net(sk), TCP_MIB_INERRS); 1445 goto discard; 1446 } 1447 EXPORT_SYMBOL(tcp_v4_do_rcv); 1448 1449 void tcp_v4_early_demux(struct sk_buff *skb) 1450 { 1451 const struct iphdr *iph; 1452 const struct tcphdr *th; 1453 struct sock *sk; 1454 1455 if (skb->pkt_type != PACKET_HOST) 1456 return; 1457 1458 if (!pskb_may_pull(skb, skb_transport_offset(skb) + sizeof(struct tcphdr))) 1459 return; 1460 1461 iph = ip_hdr(skb); 1462 th = tcp_hdr(skb); 1463 1464 if (th->doff < sizeof(struct tcphdr) / 4) 1465 return; 1466 1467 sk = __inet_lookup_established(dev_net(skb->dev), &tcp_hashinfo, 1468 iph->saddr, th->source, 1469 iph->daddr, ntohs(th->dest), 1470 skb->skb_iif); 1471 if (sk) { 1472 skb->sk = sk; 1473 skb->destructor = sock_edemux; 1474 if (sk_fullsock(sk)) { 1475 struct dst_entry *dst = READ_ONCE(sk->sk_rx_dst); 1476 1477 if (dst) 1478 dst = dst_check(dst, 0); 1479 if (dst && 1480 inet_sk(sk)->rx_dst_ifindex == skb->skb_iif) 1481 skb_dst_set_noref(skb, dst); 1482 } 1483 } 1484 } 1485 1486 /* Packet is added to VJ-style prequeue for processing in process 1487 * context, if a reader task is waiting. Apparently, this exciting 1488 * idea (VJ's mail "Re: query about TCP header on tcp-ip" of 07 Sep 93) 1489 * failed somewhere. Latency? Burstiness? Well, at least now we will 1490 * see, why it failed. 8)8) --ANK 1491 * 1492 */ 1493 bool tcp_prequeue(struct sock *sk, struct sk_buff *skb) 1494 { 1495 struct tcp_sock *tp = tcp_sk(sk); 1496 1497 if (sysctl_tcp_low_latency || !tp->ucopy.task) 1498 return false; 1499 1500 if (skb->len <= tcp_hdrlen(skb) && 1501 skb_queue_len(&tp->ucopy.prequeue) == 0) 1502 return false; 1503 1504 /* Before escaping RCU protected region, we need to take care of skb 1505 * dst. Prequeue is only enabled for established sockets. 1506 * For such sockets, we might need the skb dst only to set sk->sk_rx_dst 1507 * Instead of doing full sk_rx_dst validity here, let's perform 1508 * an optimistic check. 1509 */ 1510 if (likely(sk->sk_rx_dst)) 1511 skb_dst_drop(skb); 1512 else 1513 skb_dst_force_safe(skb); 1514 1515 __skb_queue_tail(&tp->ucopy.prequeue, skb); 1516 tp->ucopy.memory += skb->truesize; 1517 if (skb_queue_len(&tp->ucopy.prequeue) >= 32 || 1518 tp->ucopy.memory + atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf) { 1519 struct sk_buff *skb1; 1520 1521 BUG_ON(sock_owned_by_user(sk)); 1522 __NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPPREQUEUEDROPPED, 1523 skb_queue_len(&tp->ucopy.prequeue)); 1524 1525 while ((skb1 = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) 1526 sk_backlog_rcv(sk, skb1); 1527 1528 tp->ucopy.memory = 0; 1529 } else if (skb_queue_len(&tp->ucopy.prequeue) == 1) { 1530 wake_up_interruptible_sync_poll(sk_sleep(sk), 1531 POLLIN | POLLRDNORM | POLLRDBAND); 1532 if (!inet_csk_ack_scheduled(sk)) 1533 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 1534 (3 * tcp_rto_min(sk)) / 4, 1535 TCP_RTO_MAX); 1536 } 1537 return true; 1538 } 1539 EXPORT_SYMBOL(tcp_prequeue); 1540 1541 bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb) 1542 { 1543 u32 limit = sk->sk_rcvbuf + sk->sk_sndbuf; 1544 1545 /* Only socket owner can try to collapse/prune rx queues 1546 * to reduce memory overhead, so add a little headroom here. 1547 * Few sockets backlog are possibly concurrently non empty. 1548 */ 1549 limit += 64*1024; 1550 1551 /* In case all data was pulled from skb frags (in __pskb_pull_tail()), 1552 * we can fix skb->truesize to its real value to avoid future drops. 1553 * This is valid because skb is not yet charged to the socket. 1554 * It has been noticed pure SACK packets were sometimes dropped 1555 * (if cooked by drivers without copybreak feature). 1556 */ 1557 if (!skb->data_len) 1558 skb->truesize = SKB_TRUESIZE(skb_end_offset(skb)); 1559 1560 if (unlikely(sk_add_backlog(sk, skb, limit))) { 1561 bh_unlock_sock(sk); 1562 __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPBACKLOGDROP); 1563 return true; 1564 } 1565 return false; 1566 } 1567 EXPORT_SYMBOL(tcp_add_backlog); 1568 1569 /* 1570 * From tcp_input.c 1571 */ 1572 1573 int tcp_v4_rcv(struct sk_buff *skb) 1574 { 1575 struct net *net = dev_net(skb->dev); 1576 const struct iphdr *iph; 1577 const struct tcphdr *th; 1578 bool refcounted; 1579 struct sock *sk; 1580 int ret; 1581 1582 if (skb->pkt_type != PACKET_HOST) 1583 goto discard_it; 1584 1585 /* Count it even if it's bad */ 1586 __TCP_INC_STATS(net, TCP_MIB_INSEGS); 1587 1588 if (!pskb_may_pull(skb, sizeof(struct tcphdr))) 1589 goto discard_it; 1590 1591 th = (const struct tcphdr *)skb->data; 1592 1593 if (unlikely(th->doff < sizeof(struct tcphdr) / 4)) 1594 goto bad_packet; 1595 if (!pskb_may_pull(skb, th->doff * 4)) 1596 goto discard_it; 1597 1598 /* An explanation is required here, I think. 1599 * Packet length and doff are validated by header prediction, 1600 * provided case of th->doff==0 is eliminated. 1601 * So, we defer the checks. */ 1602 1603 if (skb_checksum_init(skb, IPPROTO_TCP, inet_compute_pseudo)) 1604 goto csum_error; 1605 1606 th = (const struct tcphdr *)skb->data; 1607 iph = ip_hdr(skb); 1608 /* This is tricky : We move IPCB at its correct location into TCP_SKB_CB() 1609 * barrier() makes sure compiler wont play fool^Waliasing games. 1610 */ 1611 memmove(&TCP_SKB_CB(skb)->header.h4, IPCB(skb), 1612 sizeof(struct inet_skb_parm)); 1613 barrier(); 1614 1615 TCP_SKB_CB(skb)->seq = ntohl(th->seq); 1616 TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin + 1617 skb->len - th->doff * 4); 1618 TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq); 1619 TCP_SKB_CB(skb)->tcp_flags = tcp_flag_byte(th); 1620 TCP_SKB_CB(skb)->tcp_tw_isn = 0; 1621 TCP_SKB_CB(skb)->ip_dsfield = ipv4_get_dsfield(iph); 1622 TCP_SKB_CB(skb)->sacked = 0; 1623 1624 lookup: 1625 sk = __inet_lookup_skb(&tcp_hashinfo, skb, __tcp_hdrlen(th), th->source, 1626 th->dest, &refcounted); 1627 if (!sk) 1628 goto no_tcp_socket; 1629 1630 process: 1631 if (sk->sk_state == TCP_TIME_WAIT) 1632 goto do_time_wait; 1633 1634 if (sk->sk_state == TCP_NEW_SYN_RECV) { 1635 struct request_sock *req = inet_reqsk(sk); 1636 struct sock *nsk; 1637 1638 sk = req->rsk_listener; 1639 if (unlikely(tcp_v4_inbound_md5_hash(sk, skb))) { 1640 sk_drops_add(sk, skb); 1641 reqsk_put(req); 1642 goto discard_it; 1643 } 1644 if (unlikely(sk->sk_state != TCP_LISTEN)) { 1645 inet_csk_reqsk_queue_drop_and_put(sk, req); 1646 goto lookup; 1647 } 1648 /* We own a reference on the listener, increase it again 1649 * as we might lose it too soon. 1650 */ 1651 sock_hold(sk); 1652 refcounted = true; 1653 nsk = tcp_check_req(sk, skb, req, false); 1654 if (!nsk) { 1655 reqsk_put(req); 1656 goto discard_and_relse; 1657 } 1658 if (nsk == sk) { 1659 reqsk_put(req); 1660 } else if (tcp_child_process(sk, nsk, skb)) { 1661 tcp_v4_send_reset(nsk, skb); 1662 goto discard_and_relse; 1663 } else { 1664 sock_put(sk); 1665 return 0; 1666 } 1667 } 1668 if (unlikely(iph->ttl < inet_sk(sk)->min_ttl)) { 1669 __NET_INC_STATS(net, LINUX_MIB_TCPMINTTLDROP); 1670 goto discard_and_relse; 1671 } 1672 1673 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) 1674 goto discard_and_relse; 1675 1676 if (tcp_v4_inbound_md5_hash(sk, skb)) 1677 goto discard_and_relse; 1678 1679 nf_reset(skb); 1680 1681 if (sk_filter(sk, skb)) 1682 goto discard_and_relse; 1683 1684 skb->dev = NULL; 1685 1686 if (sk->sk_state == TCP_LISTEN) { 1687 ret = tcp_v4_do_rcv(sk, skb); 1688 goto put_and_return; 1689 } 1690 1691 sk_incoming_cpu_update(sk); 1692 1693 bh_lock_sock_nested(sk); 1694 tcp_segs_in(tcp_sk(sk), skb); 1695 ret = 0; 1696 if (!sock_owned_by_user(sk)) { 1697 if (!tcp_prequeue(sk, skb)) 1698 ret = tcp_v4_do_rcv(sk, skb); 1699 } else if (tcp_add_backlog(sk, skb)) { 1700 goto discard_and_relse; 1701 } 1702 bh_unlock_sock(sk); 1703 1704 put_and_return: 1705 if (refcounted) 1706 sock_put(sk); 1707 1708 return ret; 1709 1710 no_tcp_socket: 1711 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) 1712 goto discard_it; 1713 1714 if (tcp_checksum_complete(skb)) { 1715 csum_error: 1716 __TCP_INC_STATS(net, TCP_MIB_CSUMERRORS); 1717 bad_packet: 1718 __TCP_INC_STATS(net, TCP_MIB_INERRS); 1719 } else { 1720 tcp_v4_send_reset(NULL, skb); 1721 } 1722 1723 discard_it: 1724 /* Discard frame. */ 1725 kfree_skb(skb); 1726 return 0; 1727 1728 discard_and_relse: 1729 sk_drops_add(sk, skb); 1730 if (refcounted) 1731 sock_put(sk); 1732 goto discard_it; 1733 1734 do_time_wait: 1735 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { 1736 inet_twsk_put(inet_twsk(sk)); 1737 goto discard_it; 1738 } 1739 1740 if (tcp_checksum_complete(skb)) { 1741 inet_twsk_put(inet_twsk(sk)); 1742 goto csum_error; 1743 } 1744 switch (tcp_timewait_state_process(inet_twsk(sk), skb, th)) { 1745 case TCP_TW_SYN: { 1746 struct sock *sk2 = inet_lookup_listener(dev_net(skb->dev), 1747 &tcp_hashinfo, skb, 1748 __tcp_hdrlen(th), 1749 iph->saddr, th->source, 1750 iph->daddr, th->dest, 1751 inet_iif(skb)); 1752 if (sk2) { 1753 inet_twsk_deschedule_put(inet_twsk(sk)); 1754 sk = sk2; 1755 refcounted = false; 1756 goto process; 1757 } 1758 /* Fall through to ACK */ 1759 } 1760 case TCP_TW_ACK: 1761 tcp_v4_timewait_ack(sk, skb); 1762 break; 1763 case TCP_TW_RST: 1764 tcp_v4_send_reset(sk, skb); 1765 inet_twsk_deschedule_put(inet_twsk(sk)); 1766 goto discard_it; 1767 case TCP_TW_SUCCESS:; 1768 } 1769 goto discard_it; 1770 } 1771 1772 static struct timewait_sock_ops tcp_timewait_sock_ops = { 1773 .twsk_obj_size = sizeof(struct tcp_timewait_sock), 1774 .twsk_unique = tcp_twsk_unique, 1775 .twsk_destructor= tcp_twsk_destructor, 1776 }; 1777 1778 void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb) 1779 { 1780 struct dst_entry *dst = skb_dst(skb); 1781 1782 if (dst && dst_hold_safe(dst)) { 1783 sk->sk_rx_dst = dst; 1784 inet_sk(sk)->rx_dst_ifindex = skb->skb_iif; 1785 } 1786 } 1787 EXPORT_SYMBOL(inet_sk_rx_dst_set); 1788 1789 const struct inet_connection_sock_af_ops ipv4_specific = { 1790 .queue_xmit = ip_queue_xmit, 1791 .send_check = tcp_v4_send_check, 1792 .rebuild_header = inet_sk_rebuild_header, 1793 .sk_rx_dst_set = inet_sk_rx_dst_set, 1794 .conn_request = tcp_v4_conn_request, 1795 .syn_recv_sock = tcp_v4_syn_recv_sock, 1796 .net_header_len = sizeof(struct iphdr), 1797 .setsockopt = ip_setsockopt, 1798 .getsockopt = ip_getsockopt, 1799 .addr2sockaddr = inet_csk_addr2sockaddr, 1800 .sockaddr_len = sizeof(struct sockaddr_in), 1801 .bind_conflict = inet_csk_bind_conflict, 1802 #ifdef CONFIG_COMPAT 1803 .compat_setsockopt = compat_ip_setsockopt, 1804 .compat_getsockopt = compat_ip_getsockopt, 1805 #endif 1806 .mtu_reduced = tcp_v4_mtu_reduced, 1807 }; 1808 EXPORT_SYMBOL(ipv4_specific); 1809 1810 #ifdef CONFIG_TCP_MD5SIG 1811 static const struct tcp_sock_af_ops tcp_sock_ipv4_specific = { 1812 .md5_lookup = tcp_v4_md5_lookup, 1813 .calc_md5_hash = tcp_v4_md5_hash_skb, 1814 .md5_parse = tcp_v4_parse_md5_keys, 1815 }; 1816 #endif 1817 1818 /* NOTE: A lot of things set to zero explicitly by call to 1819 * sk_alloc() so need not be done here. 1820 */ 1821 static int tcp_v4_init_sock(struct sock *sk) 1822 { 1823 struct inet_connection_sock *icsk = inet_csk(sk); 1824 1825 tcp_init_sock(sk); 1826 1827 icsk->icsk_af_ops = &ipv4_specific; 1828 1829 #ifdef CONFIG_TCP_MD5SIG 1830 tcp_sk(sk)->af_specific = &tcp_sock_ipv4_specific; 1831 #endif 1832 1833 return 0; 1834 } 1835 1836 void tcp_v4_destroy_sock(struct sock *sk) 1837 { 1838 struct tcp_sock *tp = tcp_sk(sk); 1839 1840 tcp_clear_xmit_timers(sk); 1841 1842 tcp_cleanup_congestion_control(sk); 1843 1844 /* Cleanup up the write buffer. */ 1845 tcp_write_queue_purge(sk); 1846 1847 /* Cleans up our, hopefully empty, out_of_order_queue. */ 1848 skb_rbtree_purge(&tp->out_of_order_queue); 1849 1850 #ifdef CONFIG_TCP_MD5SIG 1851 /* Clean up the MD5 key list, if any */ 1852 if (tp->md5sig_info) { 1853 tcp_clear_md5_list(sk); 1854 kfree_rcu(tp->md5sig_info, rcu); 1855 tp->md5sig_info = NULL; 1856 } 1857 #endif 1858 1859 /* Clean prequeue, it must be empty really */ 1860 __skb_queue_purge(&tp->ucopy.prequeue); 1861 1862 /* Clean up a referenced TCP bind bucket. */ 1863 if (inet_csk(sk)->icsk_bind_hash) 1864 inet_put_port(sk); 1865 1866 BUG_ON(tp->fastopen_rsk); 1867 1868 /* If socket is aborted during connect operation */ 1869 tcp_free_fastopen_req(tp); 1870 tcp_saved_syn_free(tp); 1871 1872 local_bh_disable(); 1873 sk_sockets_allocated_dec(sk); 1874 local_bh_enable(); 1875 1876 if (mem_cgroup_sockets_enabled && sk->sk_memcg) 1877 sock_release_memcg(sk); 1878 } 1879 EXPORT_SYMBOL(tcp_v4_destroy_sock); 1880 1881 #ifdef CONFIG_PROC_FS 1882 /* Proc filesystem TCP sock list dumping. */ 1883 1884 /* 1885 * Get next listener socket follow cur. If cur is NULL, get first socket 1886 * starting from bucket given in st->bucket; when st->bucket is zero the 1887 * very first socket in the hash table is returned. 1888 */ 1889 static void *listening_get_next(struct seq_file *seq, void *cur) 1890 { 1891 struct tcp_iter_state *st = seq->private; 1892 struct net *net = seq_file_net(seq); 1893 struct inet_listen_hashbucket *ilb; 1894 struct inet_connection_sock *icsk; 1895 struct sock *sk = cur; 1896 1897 if (!sk) { 1898 get_head: 1899 ilb = &tcp_hashinfo.listening_hash[st->bucket]; 1900 spin_lock_bh(&ilb->lock); 1901 sk = sk_head(&ilb->head); 1902 st->offset = 0; 1903 goto get_sk; 1904 } 1905 ilb = &tcp_hashinfo.listening_hash[st->bucket]; 1906 ++st->num; 1907 ++st->offset; 1908 1909 sk = sk_next(sk); 1910 get_sk: 1911 sk_for_each_from(sk) { 1912 if (!net_eq(sock_net(sk), net)) 1913 continue; 1914 if (sk->sk_family == st->family) 1915 return sk; 1916 icsk = inet_csk(sk); 1917 } 1918 spin_unlock_bh(&ilb->lock); 1919 st->offset = 0; 1920 if (++st->bucket < INET_LHTABLE_SIZE) 1921 goto get_head; 1922 return NULL; 1923 } 1924 1925 static void *listening_get_idx(struct seq_file *seq, loff_t *pos) 1926 { 1927 struct tcp_iter_state *st = seq->private; 1928 void *rc; 1929 1930 st->bucket = 0; 1931 st->offset = 0; 1932 rc = listening_get_next(seq, NULL); 1933 1934 while (rc && *pos) { 1935 rc = listening_get_next(seq, rc); 1936 --*pos; 1937 } 1938 return rc; 1939 } 1940 1941 static inline bool empty_bucket(const struct tcp_iter_state *st) 1942 { 1943 return hlist_nulls_empty(&tcp_hashinfo.ehash[st->bucket].chain); 1944 } 1945 1946 /* 1947 * Get first established socket starting from bucket given in st->bucket. 1948 * If st->bucket is zero, the very first socket in the hash is returned. 1949 */ 1950 static void *established_get_first(struct seq_file *seq) 1951 { 1952 struct tcp_iter_state *st = seq->private; 1953 struct net *net = seq_file_net(seq); 1954 void *rc = NULL; 1955 1956 st->offset = 0; 1957 for (; st->bucket <= tcp_hashinfo.ehash_mask; ++st->bucket) { 1958 struct sock *sk; 1959 struct hlist_nulls_node *node; 1960 spinlock_t *lock = inet_ehash_lockp(&tcp_hashinfo, st->bucket); 1961 1962 /* Lockless fast path for the common case of empty buckets */ 1963 if (empty_bucket(st)) 1964 continue; 1965 1966 spin_lock_bh(lock); 1967 sk_nulls_for_each(sk, node, &tcp_hashinfo.ehash[st->bucket].chain) { 1968 if (sk->sk_family != st->family || 1969 !net_eq(sock_net(sk), net)) { 1970 continue; 1971 } 1972 rc = sk; 1973 goto out; 1974 } 1975 spin_unlock_bh(lock); 1976 } 1977 out: 1978 return rc; 1979 } 1980 1981 static void *established_get_next(struct seq_file *seq, void *cur) 1982 { 1983 struct sock *sk = cur; 1984 struct hlist_nulls_node *node; 1985 struct tcp_iter_state *st = seq->private; 1986 struct net *net = seq_file_net(seq); 1987 1988 ++st->num; 1989 ++st->offset; 1990 1991 sk = sk_nulls_next(sk); 1992 1993 sk_nulls_for_each_from(sk, node) { 1994 if (sk->sk_family == st->family && net_eq(sock_net(sk), net)) 1995 return sk; 1996 } 1997 1998 spin_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket)); 1999 ++st->bucket; 2000 return established_get_first(seq); 2001 } 2002 2003 static void *established_get_idx(struct seq_file *seq, loff_t pos) 2004 { 2005 struct tcp_iter_state *st = seq->private; 2006 void *rc; 2007 2008 st->bucket = 0; 2009 rc = established_get_first(seq); 2010 2011 while (rc && pos) { 2012 rc = established_get_next(seq, rc); 2013 --pos; 2014 } 2015 return rc; 2016 } 2017 2018 static void *tcp_get_idx(struct seq_file *seq, loff_t pos) 2019 { 2020 void *rc; 2021 struct tcp_iter_state *st = seq->private; 2022 2023 st->state = TCP_SEQ_STATE_LISTENING; 2024 rc = listening_get_idx(seq, &pos); 2025 2026 if (!rc) { 2027 st->state = TCP_SEQ_STATE_ESTABLISHED; 2028 rc = established_get_idx(seq, pos); 2029 } 2030 2031 return rc; 2032 } 2033 2034 static void *tcp_seek_last_pos(struct seq_file *seq) 2035 { 2036 struct tcp_iter_state *st = seq->private; 2037 int offset = st->offset; 2038 int orig_num = st->num; 2039 void *rc = NULL; 2040 2041 switch (st->state) { 2042 case TCP_SEQ_STATE_LISTENING: 2043 if (st->bucket >= INET_LHTABLE_SIZE) 2044 break; 2045 st->state = TCP_SEQ_STATE_LISTENING; 2046 rc = listening_get_next(seq, NULL); 2047 while (offset-- && rc) 2048 rc = listening_get_next(seq, rc); 2049 if (rc) 2050 break; 2051 st->bucket = 0; 2052 st->state = TCP_SEQ_STATE_ESTABLISHED; 2053 /* Fallthrough */ 2054 case TCP_SEQ_STATE_ESTABLISHED: 2055 if (st->bucket > tcp_hashinfo.ehash_mask) 2056 break; 2057 rc = established_get_first(seq); 2058 while (offset-- && rc) 2059 rc = established_get_next(seq, rc); 2060 } 2061 2062 st->num = orig_num; 2063 2064 return rc; 2065 } 2066 2067 static void *tcp_seq_start(struct seq_file *seq, loff_t *pos) 2068 { 2069 struct tcp_iter_state *st = seq->private; 2070 void *rc; 2071 2072 if (*pos && *pos == st->last_pos) { 2073 rc = tcp_seek_last_pos(seq); 2074 if (rc) 2075 goto out; 2076 } 2077 2078 st->state = TCP_SEQ_STATE_LISTENING; 2079 st->num = 0; 2080 st->bucket = 0; 2081 st->offset = 0; 2082 rc = *pos ? tcp_get_idx(seq, *pos - 1) : SEQ_START_TOKEN; 2083 2084 out: 2085 st->last_pos = *pos; 2086 return rc; 2087 } 2088 2089 static void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos) 2090 { 2091 struct tcp_iter_state *st = seq->private; 2092 void *rc = NULL; 2093 2094 if (v == SEQ_START_TOKEN) { 2095 rc = tcp_get_idx(seq, 0); 2096 goto out; 2097 } 2098 2099 switch (st->state) { 2100 case TCP_SEQ_STATE_LISTENING: 2101 rc = listening_get_next(seq, v); 2102 if (!rc) { 2103 st->state = TCP_SEQ_STATE_ESTABLISHED; 2104 st->bucket = 0; 2105 st->offset = 0; 2106 rc = established_get_first(seq); 2107 } 2108 break; 2109 case TCP_SEQ_STATE_ESTABLISHED: 2110 rc = established_get_next(seq, v); 2111 break; 2112 } 2113 out: 2114 ++*pos; 2115 st->last_pos = *pos; 2116 return rc; 2117 } 2118 2119 static void tcp_seq_stop(struct seq_file *seq, void *v) 2120 { 2121 struct tcp_iter_state *st = seq->private; 2122 2123 switch (st->state) { 2124 case TCP_SEQ_STATE_LISTENING: 2125 if (v != SEQ_START_TOKEN) 2126 spin_unlock_bh(&tcp_hashinfo.listening_hash[st->bucket].lock); 2127 break; 2128 case TCP_SEQ_STATE_ESTABLISHED: 2129 if (v) 2130 spin_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket)); 2131 break; 2132 } 2133 } 2134 2135 int tcp_seq_open(struct inode *inode, struct file *file) 2136 { 2137 struct tcp_seq_afinfo *afinfo = PDE_DATA(inode); 2138 struct tcp_iter_state *s; 2139 int err; 2140 2141 err = seq_open_net(inode, file, &afinfo->seq_ops, 2142 sizeof(struct tcp_iter_state)); 2143 if (err < 0) 2144 return err; 2145 2146 s = ((struct seq_file *)file->private_data)->private; 2147 s->family = afinfo->family; 2148 s->last_pos = 0; 2149 return 0; 2150 } 2151 EXPORT_SYMBOL(tcp_seq_open); 2152 2153 int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo) 2154 { 2155 int rc = 0; 2156 struct proc_dir_entry *p; 2157 2158 afinfo->seq_ops.start = tcp_seq_start; 2159 afinfo->seq_ops.next = tcp_seq_next; 2160 afinfo->seq_ops.stop = tcp_seq_stop; 2161 2162 p = proc_create_data(afinfo->name, S_IRUGO, net->proc_net, 2163 afinfo->seq_fops, afinfo); 2164 if (!p) 2165 rc = -ENOMEM; 2166 return rc; 2167 } 2168 EXPORT_SYMBOL(tcp_proc_register); 2169 2170 void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo) 2171 { 2172 remove_proc_entry(afinfo->name, net->proc_net); 2173 } 2174 EXPORT_SYMBOL(tcp_proc_unregister); 2175 2176 static void get_openreq4(const struct request_sock *req, 2177 struct seq_file *f, int i) 2178 { 2179 const struct inet_request_sock *ireq = inet_rsk(req); 2180 long delta = req->rsk_timer.expires - jiffies; 2181 2182 seq_printf(f, "%4d: %08X:%04X %08X:%04X" 2183 " %02X %08X:%08X %02X:%08lX %08X %5u %8d %u %d %pK", 2184 i, 2185 ireq->ir_loc_addr, 2186 ireq->ir_num, 2187 ireq->ir_rmt_addr, 2188 ntohs(ireq->ir_rmt_port), 2189 TCP_SYN_RECV, 2190 0, 0, /* could print option size, but that is af dependent. */ 2191 1, /* timers active (only the expire timer) */ 2192 jiffies_delta_to_clock_t(delta), 2193 req->num_timeout, 2194 from_kuid_munged(seq_user_ns(f), 2195 sock_i_uid(req->rsk_listener)), 2196 0, /* non standard timer */ 2197 0, /* open_requests have no inode */ 2198 0, 2199 req); 2200 } 2201 2202 static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i) 2203 { 2204 int timer_active; 2205 unsigned long timer_expires; 2206 const struct tcp_sock *tp = tcp_sk(sk); 2207 const struct inet_connection_sock *icsk = inet_csk(sk); 2208 const struct inet_sock *inet = inet_sk(sk); 2209 const struct fastopen_queue *fastopenq = &icsk->icsk_accept_queue.fastopenq; 2210 __be32 dest = inet->inet_daddr; 2211 __be32 src = inet->inet_rcv_saddr; 2212 __u16 destp = ntohs(inet->inet_dport); 2213 __u16 srcp = ntohs(inet->inet_sport); 2214 int rx_queue; 2215 int state; 2216 2217 if (icsk->icsk_pending == ICSK_TIME_RETRANS || 2218 icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS || 2219 icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) { 2220 timer_active = 1; 2221 timer_expires = icsk->icsk_timeout; 2222 } else if (icsk->icsk_pending == ICSK_TIME_PROBE0) { 2223 timer_active = 4; 2224 timer_expires = icsk->icsk_timeout; 2225 } else if (timer_pending(&sk->sk_timer)) { 2226 timer_active = 2; 2227 timer_expires = sk->sk_timer.expires; 2228 } else { 2229 timer_active = 0; 2230 timer_expires = jiffies; 2231 } 2232 2233 state = sk_state_load(sk); 2234 if (state == TCP_LISTEN) 2235 rx_queue = sk->sk_ack_backlog; 2236 else 2237 /* Because we don't lock the socket, 2238 * we might find a transient negative value. 2239 */ 2240 rx_queue = max_t(int, tp->rcv_nxt - tp->copied_seq, 0); 2241 2242 seq_printf(f, "%4d: %08X:%04X %08X:%04X %02X %08X:%08X %02X:%08lX " 2243 "%08X %5u %8d %lu %d %pK %lu %lu %u %u %d", 2244 i, src, srcp, dest, destp, state, 2245 tp->write_seq - tp->snd_una, 2246 rx_queue, 2247 timer_active, 2248 jiffies_delta_to_clock_t(timer_expires - jiffies), 2249 icsk->icsk_retransmits, 2250 from_kuid_munged(seq_user_ns(f), sock_i_uid(sk)), 2251 icsk->icsk_probes_out, 2252 sock_i_ino(sk), 2253 atomic_read(&sk->sk_refcnt), sk, 2254 jiffies_to_clock_t(icsk->icsk_rto), 2255 jiffies_to_clock_t(icsk->icsk_ack.ato), 2256 (icsk->icsk_ack.quick << 1) | icsk->icsk_ack.pingpong, 2257 tp->snd_cwnd, 2258 state == TCP_LISTEN ? 2259 fastopenq->max_qlen : 2260 (tcp_in_initial_slowstart(tp) ? -1 : tp->snd_ssthresh)); 2261 } 2262 2263 static void get_timewait4_sock(const struct inet_timewait_sock *tw, 2264 struct seq_file *f, int i) 2265 { 2266 long delta = tw->tw_timer.expires - jiffies; 2267 __be32 dest, src; 2268 __u16 destp, srcp; 2269 2270 dest = tw->tw_daddr; 2271 src = tw->tw_rcv_saddr; 2272 destp = ntohs(tw->tw_dport); 2273 srcp = ntohs(tw->tw_sport); 2274 2275 seq_printf(f, "%4d: %08X:%04X %08X:%04X" 2276 " %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %pK", 2277 i, src, srcp, dest, destp, tw->tw_substate, 0, 0, 2278 3, jiffies_delta_to_clock_t(delta), 0, 0, 0, 0, 2279 atomic_read(&tw->tw_refcnt), tw); 2280 } 2281 2282 #define TMPSZ 150 2283 2284 static int tcp4_seq_show(struct seq_file *seq, void *v) 2285 { 2286 struct tcp_iter_state *st; 2287 struct sock *sk = v; 2288 2289 seq_setwidth(seq, TMPSZ - 1); 2290 if (v == SEQ_START_TOKEN) { 2291 seq_puts(seq, " sl local_address rem_address st tx_queue " 2292 "rx_queue tr tm->when retrnsmt uid timeout " 2293 "inode"); 2294 goto out; 2295 } 2296 st = seq->private; 2297 2298 if (sk->sk_state == TCP_TIME_WAIT) 2299 get_timewait4_sock(v, seq, st->num); 2300 else if (sk->sk_state == TCP_NEW_SYN_RECV) 2301 get_openreq4(v, seq, st->num); 2302 else 2303 get_tcp4_sock(v, seq, st->num); 2304 out: 2305 seq_pad(seq, '\n'); 2306 return 0; 2307 } 2308 2309 static const struct file_operations tcp_afinfo_seq_fops = { 2310 .owner = THIS_MODULE, 2311 .open = tcp_seq_open, 2312 .read = seq_read, 2313 .llseek = seq_lseek, 2314 .release = seq_release_net 2315 }; 2316 2317 static struct tcp_seq_afinfo tcp4_seq_afinfo = { 2318 .name = "tcp", 2319 .family = AF_INET, 2320 .seq_fops = &tcp_afinfo_seq_fops, 2321 .seq_ops = { 2322 .show = tcp4_seq_show, 2323 }, 2324 }; 2325 2326 static int __net_init tcp4_proc_init_net(struct net *net) 2327 { 2328 return tcp_proc_register(net, &tcp4_seq_afinfo); 2329 } 2330 2331 static void __net_exit tcp4_proc_exit_net(struct net *net) 2332 { 2333 tcp_proc_unregister(net, &tcp4_seq_afinfo); 2334 } 2335 2336 static struct pernet_operations tcp4_net_ops = { 2337 .init = tcp4_proc_init_net, 2338 .exit = tcp4_proc_exit_net, 2339 }; 2340 2341 int __init tcp4_proc_init(void) 2342 { 2343 return register_pernet_subsys(&tcp4_net_ops); 2344 } 2345 2346 void tcp4_proc_exit(void) 2347 { 2348 unregister_pernet_subsys(&tcp4_net_ops); 2349 } 2350 #endif /* CONFIG_PROC_FS */ 2351 2352 struct proto tcp_prot = { 2353 .name = "TCP", 2354 .owner = THIS_MODULE, 2355 .close = tcp_close, 2356 .connect = tcp_v4_connect, 2357 .disconnect = tcp_disconnect, 2358 .accept = inet_csk_accept, 2359 .ioctl = tcp_ioctl, 2360 .init = tcp_v4_init_sock, 2361 .destroy = tcp_v4_destroy_sock, 2362 .shutdown = tcp_shutdown, 2363 .setsockopt = tcp_setsockopt, 2364 .getsockopt = tcp_getsockopt, 2365 .recvmsg = tcp_recvmsg, 2366 .sendmsg = tcp_sendmsg, 2367 .sendpage = tcp_sendpage, 2368 .backlog_rcv = tcp_v4_do_rcv, 2369 .release_cb = tcp_release_cb, 2370 .hash = inet_hash, 2371 .unhash = inet_unhash, 2372 .get_port = inet_csk_get_port, 2373 .enter_memory_pressure = tcp_enter_memory_pressure, 2374 .stream_memory_free = tcp_stream_memory_free, 2375 .sockets_allocated = &tcp_sockets_allocated, 2376 .orphan_count = &tcp_orphan_count, 2377 .memory_allocated = &tcp_memory_allocated, 2378 .memory_pressure = &tcp_memory_pressure, 2379 .sysctl_mem = sysctl_tcp_mem, 2380 .sysctl_wmem = sysctl_tcp_wmem, 2381 .sysctl_rmem = sysctl_tcp_rmem, 2382 .max_header = MAX_TCP_HEADER, 2383 .obj_size = sizeof(struct tcp_sock), 2384 .slab_flags = SLAB_DESTROY_BY_RCU, 2385 .twsk_prot = &tcp_timewait_sock_ops, 2386 .rsk_prot = &tcp_request_sock_ops, 2387 .h.hashinfo = &tcp_hashinfo, 2388 .no_autobind = true, 2389 #ifdef CONFIG_COMPAT 2390 .compat_setsockopt = compat_tcp_setsockopt, 2391 .compat_getsockopt = compat_tcp_getsockopt, 2392 #endif 2393 .diag_destroy = tcp_abort, 2394 }; 2395 EXPORT_SYMBOL(tcp_prot); 2396 2397 static void __net_exit tcp_sk_exit(struct net *net) 2398 { 2399 int cpu; 2400 2401 for_each_possible_cpu(cpu) 2402 inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.tcp_sk, cpu)); 2403 free_percpu(net->ipv4.tcp_sk); 2404 } 2405 2406 static int __net_init tcp_sk_init(struct net *net) 2407 { 2408 int res, cpu; 2409 2410 net->ipv4.tcp_sk = alloc_percpu(struct sock *); 2411 if (!net->ipv4.tcp_sk) 2412 return -ENOMEM; 2413 2414 for_each_possible_cpu(cpu) { 2415 struct sock *sk; 2416 2417 res = inet_ctl_sock_create(&sk, PF_INET, SOCK_RAW, 2418 IPPROTO_TCP, net); 2419 if (res) 2420 goto fail; 2421 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE); 2422 *per_cpu_ptr(net->ipv4.tcp_sk, cpu) = sk; 2423 } 2424 2425 net->ipv4.sysctl_tcp_ecn = 2; 2426 net->ipv4.sysctl_tcp_ecn_fallback = 1; 2427 2428 net->ipv4.sysctl_tcp_base_mss = TCP_BASE_MSS; 2429 net->ipv4.sysctl_tcp_probe_threshold = TCP_PROBE_THRESHOLD; 2430 net->ipv4.sysctl_tcp_probe_interval = TCP_PROBE_INTERVAL; 2431 2432 net->ipv4.sysctl_tcp_keepalive_time = TCP_KEEPALIVE_TIME; 2433 net->ipv4.sysctl_tcp_keepalive_probes = TCP_KEEPALIVE_PROBES; 2434 net->ipv4.sysctl_tcp_keepalive_intvl = TCP_KEEPALIVE_INTVL; 2435 2436 net->ipv4.sysctl_tcp_syn_retries = TCP_SYN_RETRIES; 2437 net->ipv4.sysctl_tcp_synack_retries = TCP_SYNACK_RETRIES; 2438 net->ipv4.sysctl_tcp_syncookies = 1; 2439 net->ipv4.sysctl_tcp_reordering = TCP_FASTRETRANS_THRESH; 2440 net->ipv4.sysctl_tcp_retries1 = TCP_RETR1; 2441 net->ipv4.sysctl_tcp_retries2 = TCP_RETR2; 2442 net->ipv4.sysctl_tcp_orphan_retries = 0; 2443 net->ipv4.sysctl_tcp_fin_timeout = TCP_FIN_TIMEOUT; 2444 net->ipv4.sysctl_tcp_notsent_lowat = UINT_MAX; 2445 2446 return 0; 2447 fail: 2448 tcp_sk_exit(net); 2449 2450 return res; 2451 } 2452 2453 static void __net_exit tcp_sk_exit_batch(struct list_head *net_exit_list) 2454 { 2455 inet_twsk_purge(&tcp_hashinfo, &tcp_death_row, AF_INET); 2456 } 2457 2458 static struct pernet_operations __net_initdata tcp_sk_ops = { 2459 .init = tcp_sk_init, 2460 .exit = tcp_sk_exit, 2461 .exit_batch = tcp_sk_exit_batch, 2462 }; 2463 2464 void __init tcp_v4_init(void) 2465 { 2466 inet_hashinfo_init(&tcp_hashinfo); 2467 if (register_pernet_subsys(&tcp_sk_ops)) 2468 panic("Failed to create the TCP control socket.\n"); 2469 } 2470