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