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 * Version: $Id: tcp_ipv4.c,v 1.240 2002/02/01 22:01:04 davem Exp $ 9 * 10 * IPv4 specific functions 11 * 12 * 13 * code split from: 14 * linux/ipv4/tcp.c 15 * linux/ipv4/tcp_input.c 16 * linux/ipv4/tcp_output.c 17 * 18 * See tcp.c for author information 19 * 20 * This program is free software; you can redistribute it and/or 21 * modify it under the terms of the GNU General Public License 22 * as published by the Free Software Foundation; either version 23 * 2 of the License, or (at your option) any later version. 24 */ 25 26 /* 27 * Changes: 28 * David S. Miller : New socket lookup architecture. 29 * This code is dedicated to John Dyson. 30 * David S. Miller : Change semantics of established hash, 31 * half is devoted to TIME_WAIT sockets 32 * and the rest go in the other half. 33 * Andi Kleen : Add support for syncookies and fixed 34 * some bugs: ip options weren't passed to 35 * the TCP layer, missed a check for an 36 * ACK bit. 37 * Andi Kleen : Implemented fast path mtu discovery. 38 * Fixed many serious bugs in the 39 * request_sock handling and moved 40 * most of it into the af independent code. 41 * Added tail drop and some other bugfixes. 42 * Added new listen semantics. 43 * Mike McLagan : Routing by source 44 * Juan Jose Ciarlante: ip_dynaddr bits 45 * Andi Kleen: various fixes. 46 * Vitaly E. Lavrov : Transparent proxy revived after year 47 * coma. 48 * Andi Kleen : Fix new listen. 49 * Andi Kleen : Fix accept error reporting. 50 * YOSHIFUJI Hideaki @USAGI and: Support IPV6_V6ONLY socket option, which 51 * Alexey Kuznetsov allow both IPv4 and IPv6 sockets to bind 52 * a single port at the same time. 53 */ 54 55 #include <linux/config.h> 56 57 #include <linux/types.h> 58 #include <linux/fcntl.h> 59 #include <linux/module.h> 60 #include <linux/random.h> 61 #include <linux/cache.h> 62 #include <linux/jhash.h> 63 #include <linux/init.h> 64 #include <linux/times.h> 65 66 #include <net/icmp.h> 67 #include <net/inet_hashtables.h> 68 #include <net/tcp.h> 69 #include <net/transp_v6.h> 70 #include <net/ipv6.h> 71 #include <net/inet_common.h> 72 #include <net/timewait_sock.h> 73 #include <net/xfrm.h> 74 75 #include <linux/inet.h> 76 #include <linux/ipv6.h> 77 #include <linux/stddef.h> 78 #include <linux/proc_fs.h> 79 #include <linux/seq_file.h> 80 81 int sysctl_tcp_tw_reuse; 82 int sysctl_tcp_low_latency; 83 84 /* Check TCP sequence numbers in ICMP packets. */ 85 #define ICMP_MIN_LENGTH 8 86 87 /* Socket used for sending RSTs */ 88 static struct socket *tcp_socket; 89 90 void tcp_v4_send_check(struct sock *sk, int len, struct sk_buff *skb); 91 92 struct inet_hashinfo __cacheline_aligned tcp_hashinfo = { 93 .lhash_lock = RW_LOCK_UNLOCKED, 94 .lhash_users = ATOMIC_INIT(0), 95 .lhash_wait = __WAIT_QUEUE_HEAD_INITIALIZER(tcp_hashinfo.lhash_wait), 96 }; 97 98 static int tcp_v4_get_port(struct sock *sk, unsigned short snum) 99 { 100 return inet_csk_get_port(&tcp_hashinfo, sk, snum, 101 inet_csk_bind_conflict); 102 } 103 104 static void tcp_v4_hash(struct sock *sk) 105 { 106 inet_hash(&tcp_hashinfo, sk); 107 } 108 109 void tcp_unhash(struct sock *sk) 110 { 111 inet_unhash(&tcp_hashinfo, sk); 112 } 113 114 static inline __u32 tcp_v4_init_sequence(struct sock *sk, struct sk_buff *skb) 115 { 116 return secure_tcp_sequence_number(skb->nh.iph->daddr, 117 skb->nh.iph->saddr, 118 skb->h.th->dest, 119 skb->h.th->source); 120 } 121 122 int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp) 123 { 124 const struct tcp_timewait_sock *tcptw = tcp_twsk(sktw); 125 struct tcp_sock *tp = tcp_sk(sk); 126 127 /* With PAWS, it is safe from the viewpoint 128 of data integrity. Even without PAWS it is safe provided sequence 129 spaces do not overlap i.e. at data rates <= 80Mbit/sec. 130 131 Actually, the idea is close to VJ's one, only timestamp cache is 132 held not per host, but per port pair and TW bucket is used as state 133 holder. 134 135 If TW bucket has been already destroyed we fall back to VJ's scheme 136 and use initial timestamp retrieved from peer table. 137 */ 138 if (tcptw->tw_ts_recent_stamp && 139 (twp == NULL || (sysctl_tcp_tw_reuse && 140 xtime.tv_sec - tcptw->tw_ts_recent_stamp > 1))) { 141 tp->write_seq = tcptw->tw_snd_nxt + 65535 + 2; 142 if (tp->write_seq == 0) 143 tp->write_seq = 1; 144 tp->rx_opt.ts_recent = tcptw->tw_ts_recent; 145 tp->rx_opt.ts_recent_stamp = tcptw->tw_ts_recent_stamp; 146 sock_hold(sktw); 147 return 1; 148 } 149 150 return 0; 151 } 152 153 EXPORT_SYMBOL_GPL(tcp_twsk_unique); 154 155 /* This will initiate an outgoing connection. */ 156 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len) 157 { 158 struct inet_sock *inet = inet_sk(sk); 159 struct tcp_sock *tp = tcp_sk(sk); 160 struct sockaddr_in *usin = (struct sockaddr_in *)uaddr; 161 struct rtable *rt; 162 u32 daddr, nexthop; 163 int tmp; 164 int err; 165 166 if (addr_len < sizeof(struct sockaddr_in)) 167 return -EINVAL; 168 169 if (usin->sin_family != AF_INET) 170 return -EAFNOSUPPORT; 171 172 nexthop = daddr = usin->sin_addr.s_addr; 173 if (inet->opt && inet->opt->srr) { 174 if (!daddr) 175 return -EINVAL; 176 nexthop = inet->opt->faddr; 177 } 178 179 tmp = ip_route_connect(&rt, nexthop, inet->saddr, 180 RT_CONN_FLAGS(sk), sk->sk_bound_dev_if, 181 IPPROTO_TCP, 182 inet->sport, usin->sin_port, sk); 183 if (tmp < 0) 184 return tmp; 185 186 if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) { 187 ip_rt_put(rt); 188 return -ENETUNREACH; 189 } 190 191 if (!inet->opt || !inet->opt->srr) 192 daddr = rt->rt_dst; 193 194 if (!inet->saddr) 195 inet->saddr = rt->rt_src; 196 inet->rcv_saddr = inet->saddr; 197 198 if (tp->rx_opt.ts_recent_stamp && inet->daddr != daddr) { 199 /* Reset inherited state */ 200 tp->rx_opt.ts_recent = 0; 201 tp->rx_opt.ts_recent_stamp = 0; 202 tp->write_seq = 0; 203 } 204 205 if (tcp_death_row.sysctl_tw_recycle && 206 !tp->rx_opt.ts_recent_stamp && rt->rt_dst == daddr) { 207 struct inet_peer *peer = rt_get_peer(rt); 208 209 /* VJ's idea. We save last timestamp seen from 210 * the destination in peer table, when entering state TIME-WAIT 211 * and initialize rx_opt.ts_recent from it, when trying new connection. 212 */ 213 214 if (peer && peer->tcp_ts_stamp + TCP_PAWS_MSL >= xtime.tv_sec) { 215 tp->rx_opt.ts_recent_stamp = peer->tcp_ts_stamp; 216 tp->rx_opt.ts_recent = peer->tcp_ts; 217 } 218 } 219 220 inet->dport = usin->sin_port; 221 inet->daddr = daddr; 222 223 inet_csk(sk)->icsk_ext_hdr_len = 0; 224 if (inet->opt) 225 inet_csk(sk)->icsk_ext_hdr_len = inet->opt->optlen; 226 227 tp->rx_opt.mss_clamp = 536; 228 229 /* Socket identity is still unknown (sport may be zero). 230 * However we set state to SYN-SENT and not releasing socket 231 * lock select source port, enter ourselves into the hash tables and 232 * complete initialization after this. 233 */ 234 tcp_set_state(sk, TCP_SYN_SENT); 235 err = inet_hash_connect(&tcp_death_row, sk); 236 if (err) 237 goto failure; 238 239 err = ip_route_newports(&rt, IPPROTO_TCP, inet->sport, inet->dport, sk); 240 if (err) 241 goto failure; 242 243 /* OK, now commit destination to socket. */ 244 sk_setup_caps(sk, &rt->u.dst); 245 246 if (!tp->write_seq) 247 tp->write_seq = secure_tcp_sequence_number(inet->saddr, 248 inet->daddr, 249 inet->sport, 250 usin->sin_port); 251 252 inet->id = tp->write_seq ^ jiffies; 253 254 err = tcp_connect(sk); 255 rt = NULL; 256 if (err) 257 goto failure; 258 259 return 0; 260 261 failure: 262 /* This unhashes the socket and releases the local port, if necessary. */ 263 tcp_set_state(sk, TCP_CLOSE); 264 ip_rt_put(rt); 265 sk->sk_route_caps = 0; 266 inet->dport = 0; 267 return err; 268 } 269 270 /* 271 * This routine does path mtu discovery as defined in RFC1191. 272 */ 273 static void do_pmtu_discovery(struct sock *sk, struct iphdr *iph, u32 mtu) 274 { 275 struct dst_entry *dst; 276 struct inet_sock *inet = inet_sk(sk); 277 278 /* We are not interested in TCP_LISTEN and open_requests (SYN-ACKs 279 * send out by Linux are always <576bytes so they should go through 280 * unfragmented). 281 */ 282 if (sk->sk_state == TCP_LISTEN) 283 return; 284 285 /* We don't check in the destentry if pmtu discovery is forbidden 286 * on this route. We just assume that no packet_to_big packets 287 * are send back when pmtu discovery is not active. 288 * There is a small race when the user changes this flag in the 289 * route, but I think that's acceptable. 290 */ 291 if ((dst = __sk_dst_check(sk, 0)) == NULL) 292 return; 293 294 dst->ops->update_pmtu(dst, mtu); 295 296 /* Something is about to be wrong... Remember soft error 297 * for the case, if this connection will not able to recover. 298 */ 299 if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst)) 300 sk->sk_err_soft = EMSGSIZE; 301 302 mtu = dst_mtu(dst); 303 304 if (inet->pmtudisc != IP_PMTUDISC_DONT && 305 inet_csk(sk)->icsk_pmtu_cookie > mtu) { 306 tcp_sync_mss(sk, mtu); 307 308 /* Resend the TCP packet because it's 309 * clear that the old packet has been 310 * dropped. This is the new "fast" path mtu 311 * discovery. 312 */ 313 tcp_simple_retransmit(sk); 314 } /* else let the usual retransmit timer handle it */ 315 } 316 317 /* 318 * This routine is called by the ICMP module when it gets some 319 * sort of error condition. If err < 0 then the socket should 320 * be closed and the error returned to the user. If err > 0 321 * it's just the icmp type << 8 | icmp code. After adjustment 322 * header points to the first 8 bytes of the tcp header. We need 323 * to find the appropriate port. 324 * 325 * The locking strategy used here is very "optimistic". When 326 * someone else accesses the socket the ICMP is just dropped 327 * and for some paths there is no check at all. 328 * A more general error queue to queue errors for later handling 329 * is probably better. 330 * 331 */ 332 333 void tcp_v4_err(struct sk_buff *skb, u32 info) 334 { 335 struct iphdr *iph = (struct iphdr *)skb->data; 336 struct tcphdr *th = (struct tcphdr *)(skb->data + (iph->ihl << 2)); 337 struct tcp_sock *tp; 338 struct inet_sock *inet; 339 int type = skb->h.icmph->type; 340 int code = skb->h.icmph->code; 341 struct sock *sk; 342 __u32 seq; 343 int err; 344 345 if (skb->len < (iph->ihl << 2) + 8) { 346 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS); 347 return; 348 } 349 350 sk = inet_lookup(&tcp_hashinfo, iph->daddr, th->dest, iph->saddr, 351 th->source, inet_iif(skb)); 352 if (!sk) { 353 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS); 354 return; 355 } 356 if (sk->sk_state == TCP_TIME_WAIT) { 357 inet_twsk_put((struct inet_timewait_sock *)sk); 358 return; 359 } 360 361 bh_lock_sock(sk); 362 /* If too many ICMPs get dropped on busy 363 * servers this needs to be solved differently. 364 */ 365 if (sock_owned_by_user(sk)) 366 NET_INC_STATS_BH(LINUX_MIB_LOCKDROPPEDICMPS); 367 368 if (sk->sk_state == TCP_CLOSE) 369 goto out; 370 371 tp = tcp_sk(sk); 372 seq = ntohl(th->seq); 373 if (sk->sk_state != TCP_LISTEN && 374 !between(seq, tp->snd_una, tp->snd_nxt)) { 375 NET_INC_STATS(LINUX_MIB_OUTOFWINDOWICMPS); 376 goto out; 377 } 378 379 switch (type) { 380 case ICMP_SOURCE_QUENCH: 381 /* Just silently ignore these. */ 382 goto out; 383 case ICMP_PARAMETERPROB: 384 err = EPROTO; 385 break; 386 case ICMP_DEST_UNREACH: 387 if (code > NR_ICMP_UNREACH) 388 goto out; 389 390 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */ 391 if (!sock_owned_by_user(sk)) 392 do_pmtu_discovery(sk, iph, info); 393 goto out; 394 } 395 396 err = icmp_err_convert[code].errno; 397 break; 398 case ICMP_TIME_EXCEEDED: 399 err = EHOSTUNREACH; 400 break; 401 default: 402 goto out; 403 } 404 405 switch (sk->sk_state) { 406 struct request_sock *req, **prev; 407 case TCP_LISTEN: 408 if (sock_owned_by_user(sk)) 409 goto out; 410 411 req = inet_csk_search_req(sk, &prev, th->dest, 412 iph->daddr, iph->saddr); 413 if (!req) 414 goto out; 415 416 /* ICMPs are not backlogged, hence we cannot get 417 an established socket here. 418 */ 419 BUG_TRAP(!req->sk); 420 421 if (seq != tcp_rsk(req)->snt_isn) { 422 NET_INC_STATS_BH(LINUX_MIB_OUTOFWINDOWICMPS); 423 goto out; 424 } 425 426 /* 427 * Still in SYN_RECV, just remove it silently. 428 * There is no good way to pass the error to the newly 429 * created socket, and POSIX does not want network 430 * errors returned from accept(). 431 */ 432 inet_csk_reqsk_queue_drop(sk, req, prev); 433 goto out; 434 435 case TCP_SYN_SENT: 436 case TCP_SYN_RECV: /* Cannot happen. 437 It can f.e. if SYNs crossed. 438 */ 439 if (!sock_owned_by_user(sk)) { 440 TCP_INC_STATS_BH(TCP_MIB_ATTEMPTFAILS); 441 sk->sk_err = err; 442 443 sk->sk_error_report(sk); 444 445 tcp_done(sk); 446 } else { 447 sk->sk_err_soft = err; 448 } 449 goto out; 450 } 451 452 /* If we've already connected we will keep trying 453 * until we time out, or the user gives up. 454 * 455 * rfc1122 4.2.3.9 allows to consider as hard errors 456 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too, 457 * but it is obsoleted by pmtu discovery). 458 * 459 * Note, that in modern internet, where routing is unreliable 460 * and in each dark corner broken firewalls sit, sending random 461 * errors ordered by their masters even this two messages finally lose 462 * their original sense (even Linux sends invalid PORT_UNREACHs) 463 * 464 * Now we are in compliance with RFCs. 465 * --ANK (980905) 466 */ 467 468 inet = inet_sk(sk); 469 if (!sock_owned_by_user(sk) && inet->recverr) { 470 sk->sk_err = err; 471 sk->sk_error_report(sk); 472 } else { /* Only an error on timeout */ 473 sk->sk_err_soft = err; 474 } 475 476 out: 477 bh_unlock_sock(sk); 478 sock_put(sk); 479 } 480 481 /* This routine computes an IPv4 TCP checksum. */ 482 void tcp_v4_send_check(struct sock *sk, int len, struct sk_buff *skb) 483 { 484 struct inet_sock *inet = inet_sk(sk); 485 struct tcphdr *th = skb->h.th; 486 487 if (skb->ip_summed == CHECKSUM_HW) { 488 th->check = ~tcp_v4_check(th, len, inet->saddr, inet->daddr, 0); 489 skb->csum = offsetof(struct tcphdr, check); 490 } else { 491 th->check = tcp_v4_check(th, len, inet->saddr, inet->daddr, 492 csum_partial((char *)th, 493 th->doff << 2, 494 skb->csum)); 495 } 496 } 497 498 /* 499 * This routine will send an RST to the other tcp. 500 * 501 * Someone asks: why I NEVER use socket parameters (TOS, TTL etc.) 502 * for reset. 503 * Answer: if a packet caused RST, it is not for a socket 504 * existing in our system, if it is matched to a socket, 505 * it is just duplicate segment or bug in other side's TCP. 506 * So that we build reply only basing on parameters 507 * arrived with segment. 508 * Exception: precedence violation. We do not implement it in any case. 509 */ 510 511 static void tcp_v4_send_reset(struct sk_buff *skb) 512 { 513 struct tcphdr *th = skb->h.th; 514 struct tcphdr rth; 515 struct ip_reply_arg arg; 516 517 /* Never send a reset in response to a reset. */ 518 if (th->rst) 519 return; 520 521 if (((struct rtable *)skb->dst)->rt_type != RTN_LOCAL) 522 return; 523 524 /* Swap the send and the receive. */ 525 memset(&rth, 0, sizeof(struct tcphdr)); 526 rth.dest = th->source; 527 rth.source = th->dest; 528 rth.doff = sizeof(struct tcphdr) / 4; 529 rth.rst = 1; 530 531 if (th->ack) { 532 rth.seq = th->ack_seq; 533 } else { 534 rth.ack = 1; 535 rth.ack_seq = htonl(ntohl(th->seq) + th->syn + th->fin + 536 skb->len - (th->doff << 2)); 537 } 538 539 memset(&arg, 0, sizeof arg); 540 arg.iov[0].iov_base = (unsigned char *)&rth; 541 arg.iov[0].iov_len = sizeof rth; 542 arg.csum = csum_tcpudp_nofold(skb->nh.iph->daddr, 543 skb->nh.iph->saddr, /*XXX*/ 544 sizeof(struct tcphdr), IPPROTO_TCP, 0); 545 arg.csumoffset = offsetof(struct tcphdr, check) / 2; 546 547 ip_send_reply(tcp_socket->sk, skb, &arg, sizeof rth); 548 549 TCP_INC_STATS_BH(TCP_MIB_OUTSEGS); 550 TCP_INC_STATS_BH(TCP_MIB_OUTRSTS); 551 } 552 553 /* The code following below sending ACKs in SYN-RECV and TIME-WAIT states 554 outside socket context is ugly, certainly. What can I do? 555 */ 556 557 static void tcp_v4_send_ack(struct sk_buff *skb, u32 seq, u32 ack, 558 u32 win, u32 ts) 559 { 560 struct tcphdr *th = skb->h.th; 561 struct { 562 struct tcphdr th; 563 u32 tsopt[3]; 564 } rep; 565 struct ip_reply_arg arg; 566 567 memset(&rep.th, 0, sizeof(struct tcphdr)); 568 memset(&arg, 0, sizeof arg); 569 570 arg.iov[0].iov_base = (unsigned char *)&rep; 571 arg.iov[0].iov_len = sizeof(rep.th); 572 if (ts) { 573 rep.tsopt[0] = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) | 574 (TCPOPT_TIMESTAMP << 8) | 575 TCPOLEN_TIMESTAMP); 576 rep.tsopt[1] = htonl(tcp_time_stamp); 577 rep.tsopt[2] = htonl(ts); 578 arg.iov[0].iov_len = sizeof(rep); 579 } 580 581 /* Swap the send and the receive. */ 582 rep.th.dest = th->source; 583 rep.th.source = th->dest; 584 rep.th.doff = arg.iov[0].iov_len / 4; 585 rep.th.seq = htonl(seq); 586 rep.th.ack_seq = htonl(ack); 587 rep.th.ack = 1; 588 rep.th.window = htons(win); 589 590 arg.csum = csum_tcpudp_nofold(skb->nh.iph->daddr, 591 skb->nh.iph->saddr, /*XXX*/ 592 arg.iov[0].iov_len, IPPROTO_TCP, 0); 593 arg.csumoffset = offsetof(struct tcphdr, check) / 2; 594 595 ip_send_reply(tcp_socket->sk, skb, &arg, arg.iov[0].iov_len); 596 597 TCP_INC_STATS_BH(TCP_MIB_OUTSEGS); 598 } 599 600 static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb) 601 { 602 struct inet_timewait_sock *tw = inet_twsk(sk); 603 const struct tcp_timewait_sock *tcptw = tcp_twsk(sk); 604 605 tcp_v4_send_ack(skb, tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt, 606 tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale, tcptw->tw_ts_recent); 607 608 inet_twsk_put(tw); 609 } 610 611 static void tcp_v4_reqsk_send_ack(struct sk_buff *skb, struct request_sock *req) 612 { 613 tcp_v4_send_ack(skb, tcp_rsk(req)->snt_isn + 1, tcp_rsk(req)->rcv_isn + 1, req->rcv_wnd, 614 req->ts_recent); 615 } 616 617 /* 618 * Send a SYN-ACK after having received an ACK. 619 * This still operates on a request_sock only, not on a big 620 * socket. 621 */ 622 static int tcp_v4_send_synack(struct sock *sk, struct request_sock *req, 623 struct dst_entry *dst) 624 { 625 const struct inet_request_sock *ireq = inet_rsk(req); 626 int err = -1; 627 struct sk_buff * skb; 628 629 /* First, grab a route. */ 630 if (!dst && (dst = inet_csk_route_req(sk, req)) == NULL) 631 goto out; 632 633 skb = tcp_make_synack(sk, dst, req); 634 635 if (skb) { 636 struct tcphdr *th = skb->h.th; 637 638 th->check = tcp_v4_check(th, skb->len, 639 ireq->loc_addr, 640 ireq->rmt_addr, 641 csum_partial((char *)th, skb->len, 642 skb->csum)); 643 644 err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr, 645 ireq->rmt_addr, 646 ireq->opt); 647 if (err == NET_XMIT_CN) 648 err = 0; 649 } 650 651 out: 652 dst_release(dst); 653 return err; 654 } 655 656 /* 657 * IPv4 request_sock destructor. 658 */ 659 static void tcp_v4_reqsk_destructor(struct request_sock *req) 660 { 661 kfree(inet_rsk(req)->opt); 662 } 663 664 #ifdef CONFIG_SYN_COOKIES 665 static void syn_flood_warning(struct sk_buff *skb) 666 { 667 static unsigned long warntime; 668 669 if (time_after(jiffies, (warntime + HZ * 60))) { 670 warntime = jiffies; 671 printk(KERN_INFO 672 "possible SYN flooding on port %d. Sending cookies.\n", 673 ntohs(skb->h.th->dest)); 674 } 675 } 676 #endif 677 678 /* 679 * Save and compile IPv4 options into the request_sock if needed. 680 */ 681 static struct ip_options *tcp_v4_save_options(struct sock *sk, 682 struct sk_buff *skb) 683 { 684 struct ip_options *opt = &(IPCB(skb)->opt); 685 struct ip_options *dopt = NULL; 686 687 if (opt && opt->optlen) { 688 int opt_size = optlength(opt); 689 dopt = kmalloc(opt_size, GFP_ATOMIC); 690 if (dopt) { 691 if (ip_options_echo(dopt, skb)) { 692 kfree(dopt); 693 dopt = NULL; 694 } 695 } 696 } 697 return dopt; 698 } 699 700 struct request_sock_ops tcp_request_sock_ops = { 701 .family = PF_INET, 702 .obj_size = sizeof(struct tcp_request_sock), 703 .rtx_syn_ack = tcp_v4_send_synack, 704 .send_ack = tcp_v4_reqsk_send_ack, 705 .destructor = tcp_v4_reqsk_destructor, 706 .send_reset = tcp_v4_send_reset, 707 }; 708 709 static struct timewait_sock_ops tcp_timewait_sock_ops = { 710 .twsk_obj_size = sizeof(struct tcp_timewait_sock), 711 .twsk_unique = tcp_twsk_unique, 712 }; 713 714 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb) 715 { 716 struct inet_request_sock *ireq; 717 struct tcp_options_received tmp_opt; 718 struct request_sock *req; 719 __u32 saddr = skb->nh.iph->saddr; 720 __u32 daddr = skb->nh.iph->daddr; 721 __u32 isn = TCP_SKB_CB(skb)->when; 722 struct dst_entry *dst = NULL; 723 #ifdef CONFIG_SYN_COOKIES 724 int want_cookie = 0; 725 #else 726 #define want_cookie 0 /* Argh, why doesn't gcc optimize this :( */ 727 #endif 728 729 /* Never answer to SYNs send to broadcast or multicast */ 730 if (((struct rtable *)skb->dst)->rt_flags & 731 (RTCF_BROADCAST | RTCF_MULTICAST)) 732 goto drop; 733 734 /* TW buckets are converted to open requests without 735 * limitations, they conserve resources and peer is 736 * evidently real one. 737 */ 738 if (inet_csk_reqsk_queue_is_full(sk) && !isn) { 739 #ifdef CONFIG_SYN_COOKIES 740 if (sysctl_tcp_syncookies) { 741 want_cookie = 1; 742 } else 743 #endif 744 goto drop; 745 } 746 747 /* Accept backlog is full. If we have already queued enough 748 * of warm entries in syn queue, drop request. It is better than 749 * clogging syn queue with openreqs with exponentially increasing 750 * timeout. 751 */ 752 if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1) 753 goto drop; 754 755 req = reqsk_alloc(&tcp_request_sock_ops); 756 if (!req) 757 goto drop; 758 759 tcp_clear_options(&tmp_opt); 760 tmp_opt.mss_clamp = 536; 761 tmp_opt.user_mss = tcp_sk(sk)->rx_opt.user_mss; 762 763 tcp_parse_options(skb, &tmp_opt, 0); 764 765 if (want_cookie) { 766 tcp_clear_options(&tmp_opt); 767 tmp_opt.saw_tstamp = 0; 768 } 769 770 if (tmp_opt.saw_tstamp && !tmp_opt.rcv_tsval) { 771 /* Some OSes (unknown ones, but I see them on web server, which 772 * contains information interesting only for windows' 773 * users) do not send their stamp in SYN. It is easy case. 774 * We simply do not advertise TS support. 775 */ 776 tmp_opt.saw_tstamp = 0; 777 tmp_opt.tstamp_ok = 0; 778 } 779 tmp_opt.tstamp_ok = tmp_opt.saw_tstamp; 780 781 tcp_openreq_init(req, &tmp_opt, skb); 782 783 ireq = inet_rsk(req); 784 ireq->loc_addr = daddr; 785 ireq->rmt_addr = saddr; 786 ireq->opt = tcp_v4_save_options(sk, skb); 787 if (!want_cookie) 788 TCP_ECN_create_request(req, skb->h.th); 789 790 if (want_cookie) { 791 #ifdef CONFIG_SYN_COOKIES 792 syn_flood_warning(skb); 793 #endif 794 isn = cookie_v4_init_sequence(sk, skb, &req->mss); 795 } else if (!isn) { 796 struct inet_peer *peer = NULL; 797 798 /* VJ's idea. We save last timestamp seen 799 * from the destination in peer table, when entering 800 * state TIME-WAIT, and check against it before 801 * accepting new connection request. 802 * 803 * If "isn" is not zero, this request hit alive 804 * timewait bucket, so that all the necessary checks 805 * are made in the function processing timewait state. 806 */ 807 if (tmp_opt.saw_tstamp && 808 tcp_death_row.sysctl_tw_recycle && 809 (dst = inet_csk_route_req(sk, req)) != NULL && 810 (peer = rt_get_peer((struct rtable *)dst)) != NULL && 811 peer->v4daddr == saddr) { 812 if (xtime.tv_sec < peer->tcp_ts_stamp + TCP_PAWS_MSL && 813 (s32)(peer->tcp_ts - req->ts_recent) > 814 TCP_PAWS_WINDOW) { 815 NET_INC_STATS_BH(LINUX_MIB_PAWSPASSIVEREJECTED); 816 dst_release(dst); 817 goto drop_and_free; 818 } 819 } 820 /* Kill the following clause, if you dislike this way. */ 821 else if (!sysctl_tcp_syncookies && 822 (sysctl_max_syn_backlog - inet_csk_reqsk_queue_len(sk) < 823 (sysctl_max_syn_backlog >> 2)) && 824 (!peer || !peer->tcp_ts_stamp) && 825 (!dst || !dst_metric(dst, RTAX_RTT))) { 826 /* Without syncookies last quarter of 827 * backlog is filled with destinations, 828 * proven to be alive. 829 * It means that we continue to communicate 830 * to destinations, already remembered 831 * to the moment of synflood. 832 */ 833 LIMIT_NETDEBUG(KERN_DEBUG "TCP: drop open " 834 "request from %u.%u.%u.%u/%u\n", 835 NIPQUAD(saddr), 836 ntohs(skb->h.th->source)); 837 dst_release(dst); 838 goto drop_and_free; 839 } 840 841 isn = tcp_v4_init_sequence(sk, skb); 842 } 843 tcp_rsk(req)->snt_isn = isn; 844 845 if (tcp_v4_send_synack(sk, req, dst)) 846 goto drop_and_free; 847 848 if (want_cookie) { 849 reqsk_free(req); 850 } else { 851 inet_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT); 852 } 853 return 0; 854 855 drop_and_free: 856 reqsk_free(req); 857 drop: 858 TCP_INC_STATS_BH(TCP_MIB_ATTEMPTFAILS); 859 return 0; 860 } 861 862 863 /* 864 * The three way handshake has completed - we got a valid synack - 865 * now create the new socket. 866 */ 867 struct sock *tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb, 868 struct request_sock *req, 869 struct dst_entry *dst) 870 { 871 struct inet_request_sock *ireq; 872 struct inet_sock *newinet; 873 struct tcp_sock *newtp; 874 struct sock *newsk; 875 876 if (sk_acceptq_is_full(sk)) 877 goto exit_overflow; 878 879 if (!dst && (dst = inet_csk_route_req(sk, req)) == NULL) 880 goto exit; 881 882 newsk = tcp_create_openreq_child(sk, req, skb); 883 if (!newsk) 884 goto exit; 885 886 sk_setup_caps(newsk, dst); 887 888 newtp = tcp_sk(newsk); 889 newinet = inet_sk(newsk); 890 ireq = inet_rsk(req); 891 newinet->daddr = ireq->rmt_addr; 892 newinet->rcv_saddr = ireq->loc_addr; 893 newinet->saddr = ireq->loc_addr; 894 newinet->opt = ireq->opt; 895 ireq->opt = NULL; 896 newinet->mc_index = inet_iif(skb); 897 newinet->mc_ttl = skb->nh.iph->ttl; 898 inet_csk(newsk)->icsk_ext_hdr_len = 0; 899 if (newinet->opt) 900 inet_csk(newsk)->icsk_ext_hdr_len = newinet->opt->optlen; 901 newinet->id = newtp->write_seq ^ jiffies; 902 903 tcp_sync_mss(newsk, dst_mtu(dst)); 904 newtp->advmss = dst_metric(dst, RTAX_ADVMSS); 905 tcp_initialize_rcv_mss(newsk); 906 907 __inet_hash(&tcp_hashinfo, newsk, 0); 908 __inet_inherit_port(&tcp_hashinfo, sk, newsk); 909 910 return newsk; 911 912 exit_overflow: 913 NET_INC_STATS_BH(LINUX_MIB_LISTENOVERFLOWS); 914 exit: 915 NET_INC_STATS_BH(LINUX_MIB_LISTENDROPS); 916 dst_release(dst); 917 return NULL; 918 } 919 920 static struct sock *tcp_v4_hnd_req(struct sock *sk, struct sk_buff *skb) 921 { 922 struct tcphdr *th = skb->h.th; 923 struct iphdr *iph = skb->nh.iph; 924 struct sock *nsk; 925 struct request_sock **prev; 926 /* Find possible connection requests. */ 927 struct request_sock *req = inet_csk_search_req(sk, &prev, th->source, 928 iph->saddr, iph->daddr); 929 if (req) 930 return tcp_check_req(sk, skb, req, prev); 931 932 nsk = __inet_lookup_established(&tcp_hashinfo, skb->nh.iph->saddr, 933 th->source, skb->nh.iph->daddr, 934 ntohs(th->dest), inet_iif(skb)); 935 936 if (nsk) { 937 if (nsk->sk_state != TCP_TIME_WAIT) { 938 bh_lock_sock(nsk); 939 return nsk; 940 } 941 inet_twsk_put((struct inet_timewait_sock *)nsk); 942 return NULL; 943 } 944 945 #ifdef CONFIG_SYN_COOKIES 946 if (!th->rst && !th->syn && th->ack) 947 sk = cookie_v4_check(sk, skb, &(IPCB(skb)->opt)); 948 #endif 949 return sk; 950 } 951 952 static int tcp_v4_checksum_init(struct sk_buff *skb) 953 { 954 if (skb->ip_summed == CHECKSUM_HW) { 955 if (!tcp_v4_check(skb->h.th, skb->len, skb->nh.iph->saddr, 956 skb->nh.iph->daddr, skb->csum)) { 957 skb->ip_summed = CHECKSUM_UNNECESSARY; 958 return 0; 959 } 960 } 961 962 skb->csum = csum_tcpudp_nofold(skb->nh.iph->saddr, skb->nh.iph->daddr, 963 skb->len, IPPROTO_TCP, 0); 964 965 if (skb->len <= 76) { 966 return __skb_checksum_complete(skb); 967 } 968 return 0; 969 } 970 971 972 /* The socket must have it's spinlock held when we get 973 * here. 974 * 975 * We have a potential double-lock case here, so even when 976 * doing backlog processing we use the BH locking scheme. 977 * This is because we cannot sleep with the original spinlock 978 * held. 979 */ 980 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb) 981 { 982 if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */ 983 TCP_CHECK_TIMER(sk); 984 if (tcp_rcv_established(sk, skb, skb->h.th, skb->len)) 985 goto reset; 986 TCP_CHECK_TIMER(sk); 987 return 0; 988 } 989 990 if (skb->len < (skb->h.th->doff << 2) || tcp_checksum_complete(skb)) 991 goto csum_err; 992 993 if (sk->sk_state == TCP_LISTEN) { 994 struct sock *nsk = tcp_v4_hnd_req(sk, skb); 995 if (!nsk) 996 goto discard; 997 998 if (nsk != sk) { 999 if (tcp_child_process(sk, nsk, skb)) 1000 goto reset; 1001 return 0; 1002 } 1003 } 1004 1005 TCP_CHECK_TIMER(sk); 1006 if (tcp_rcv_state_process(sk, skb, skb->h.th, skb->len)) 1007 goto reset; 1008 TCP_CHECK_TIMER(sk); 1009 return 0; 1010 1011 reset: 1012 tcp_v4_send_reset(skb); 1013 discard: 1014 kfree_skb(skb); 1015 /* Be careful here. If this function gets more complicated and 1016 * gcc suffers from register pressure on the x86, sk (in %ebx) 1017 * might be destroyed here. This current version compiles correctly, 1018 * but you have been warned. 1019 */ 1020 return 0; 1021 1022 csum_err: 1023 TCP_INC_STATS_BH(TCP_MIB_INERRS); 1024 goto discard; 1025 } 1026 1027 /* 1028 * From tcp_input.c 1029 */ 1030 1031 int tcp_v4_rcv(struct sk_buff *skb) 1032 { 1033 struct tcphdr *th; 1034 struct sock *sk; 1035 int ret; 1036 1037 if (skb->pkt_type != PACKET_HOST) 1038 goto discard_it; 1039 1040 /* Count it even if it's bad */ 1041 TCP_INC_STATS_BH(TCP_MIB_INSEGS); 1042 1043 if (!pskb_may_pull(skb, sizeof(struct tcphdr))) 1044 goto discard_it; 1045 1046 th = skb->h.th; 1047 1048 if (th->doff < sizeof(struct tcphdr) / 4) 1049 goto bad_packet; 1050 if (!pskb_may_pull(skb, th->doff * 4)) 1051 goto discard_it; 1052 1053 /* An explanation is required here, I think. 1054 * Packet length and doff are validated by header prediction, 1055 * provided case of th->doff==0 is eliminated. 1056 * So, we defer the checks. */ 1057 if ((skb->ip_summed != CHECKSUM_UNNECESSARY && 1058 tcp_v4_checksum_init(skb))) 1059 goto bad_packet; 1060 1061 th = skb->h.th; 1062 TCP_SKB_CB(skb)->seq = ntohl(th->seq); 1063 TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin + 1064 skb->len - th->doff * 4); 1065 TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq); 1066 TCP_SKB_CB(skb)->when = 0; 1067 TCP_SKB_CB(skb)->flags = skb->nh.iph->tos; 1068 TCP_SKB_CB(skb)->sacked = 0; 1069 1070 sk = __inet_lookup(&tcp_hashinfo, skb->nh.iph->saddr, th->source, 1071 skb->nh.iph->daddr, ntohs(th->dest), 1072 inet_iif(skb)); 1073 1074 if (!sk) 1075 goto no_tcp_socket; 1076 1077 process: 1078 if (sk->sk_state == TCP_TIME_WAIT) 1079 goto do_time_wait; 1080 1081 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) 1082 goto discard_and_relse; 1083 nf_reset(skb); 1084 1085 if (sk_filter(sk, skb, 0)) 1086 goto discard_and_relse; 1087 1088 skb->dev = NULL; 1089 1090 bh_lock_sock(sk); 1091 ret = 0; 1092 if (!sock_owned_by_user(sk)) { 1093 if (!tcp_prequeue(sk, skb)) 1094 ret = tcp_v4_do_rcv(sk, skb); 1095 } else 1096 sk_add_backlog(sk, skb); 1097 bh_unlock_sock(sk); 1098 1099 sock_put(sk); 1100 1101 return ret; 1102 1103 no_tcp_socket: 1104 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) 1105 goto discard_it; 1106 1107 if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) { 1108 bad_packet: 1109 TCP_INC_STATS_BH(TCP_MIB_INERRS); 1110 } else { 1111 tcp_v4_send_reset(skb); 1112 } 1113 1114 discard_it: 1115 /* Discard frame. */ 1116 kfree_skb(skb); 1117 return 0; 1118 1119 discard_and_relse: 1120 sock_put(sk); 1121 goto discard_it; 1122 1123 do_time_wait: 1124 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { 1125 inet_twsk_put((struct inet_timewait_sock *) sk); 1126 goto discard_it; 1127 } 1128 1129 if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) { 1130 TCP_INC_STATS_BH(TCP_MIB_INERRS); 1131 inet_twsk_put((struct inet_timewait_sock *) sk); 1132 goto discard_it; 1133 } 1134 switch (tcp_timewait_state_process((struct inet_timewait_sock *)sk, 1135 skb, th)) { 1136 case TCP_TW_SYN: { 1137 struct sock *sk2 = inet_lookup_listener(&tcp_hashinfo, 1138 skb->nh.iph->daddr, 1139 ntohs(th->dest), 1140 inet_iif(skb)); 1141 if (sk2) { 1142 inet_twsk_deschedule((struct inet_timewait_sock *)sk, 1143 &tcp_death_row); 1144 inet_twsk_put((struct inet_timewait_sock *)sk); 1145 sk = sk2; 1146 goto process; 1147 } 1148 /* Fall through to ACK */ 1149 } 1150 case TCP_TW_ACK: 1151 tcp_v4_timewait_ack(sk, skb); 1152 break; 1153 case TCP_TW_RST: 1154 goto no_tcp_socket; 1155 case TCP_TW_SUCCESS:; 1156 } 1157 goto discard_it; 1158 } 1159 1160 /* VJ's idea. Save last timestamp seen from this destination 1161 * and hold it at least for normal timewait interval to use for duplicate 1162 * segment detection in subsequent connections, before they enter synchronized 1163 * state. 1164 */ 1165 1166 int tcp_v4_remember_stamp(struct sock *sk) 1167 { 1168 struct inet_sock *inet = inet_sk(sk); 1169 struct tcp_sock *tp = tcp_sk(sk); 1170 struct rtable *rt = (struct rtable *)__sk_dst_get(sk); 1171 struct inet_peer *peer = NULL; 1172 int release_it = 0; 1173 1174 if (!rt || rt->rt_dst != inet->daddr) { 1175 peer = inet_getpeer(inet->daddr, 1); 1176 release_it = 1; 1177 } else { 1178 if (!rt->peer) 1179 rt_bind_peer(rt, 1); 1180 peer = rt->peer; 1181 } 1182 1183 if (peer) { 1184 if ((s32)(peer->tcp_ts - tp->rx_opt.ts_recent) <= 0 || 1185 (peer->tcp_ts_stamp + TCP_PAWS_MSL < xtime.tv_sec && 1186 peer->tcp_ts_stamp <= tp->rx_opt.ts_recent_stamp)) { 1187 peer->tcp_ts_stamp = tp->rx_opt.ts_recent_stamp; 1188 peer->tcp_ts = tp->rx_opt.ts_recent; 1189 } 1190 if (release_it) 1191 inet_putpeer(peer); 1192 return 1; 1193 } 1194 1195 return 0; 1196 } 1197 1198 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw) 1199 { 1200 struct inet_peer *peer = inet_getpeer(tw->tw_daddr, 1); 1201 1202 if (peer) { 1203 const struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw); 1204 1205 if ((s32)(peer->tcp_ts - tcptw->tw_ts_recent) <= 0 || 1206 (peer->tcp_ts_stamp + TCP_PAWS_MSL < xtime.tv_sec && 1207 peer->tcp_ts_stamp <= tcptw->tw_ts_recent_stamp)) { 1208 peer->tcp_ts_stamp = tcptw->tw_ts_recent_stamp; 1209 peer->tcp_ts = tcptw->tw_ts_recent; 1210 } 1211 inet_putpeer(peer); 1212 return 1; 1213 } 1214 1215 return 0; 1216 } 1217 1218 struct inet_connection_sock_af_ops ipv4_specific = { 1219 .queue_xmit = ip_queue_xmit, 1220 .send_check = tcp_v4_send_check, 1221 .rebuild_header = inet_sk_rebuild_header, 1222 .conn_request = tcp_v4_conn_request, 1223 .syn_recv_sock = tcp_v4_syn_recv_sock, 1224 .remember_stamp = tcp_v4_remember_stamp, 1225 .net_header_len = sizeof(struct iphdr), 1226 .setsockopt = ip_setsockopt, 1227 .getsockopt = ip_getsockopt, 1228 .addr2sockaddr = inet_csk_addr2sockaddr, 1229 .sockaddr_len = sizeof(struct sockaddr_in), 1230 }; 1231 1232 /* NOTE: A lot of things set to zero explicitly by call to 1233 * sk_alloc() so need not be done here. 1234 */ 1235 static int tcp_v4_init_sock(struct sock *sk) 1236 { 1237 struct inet_connection_sock *icsk = inet_csk(sk); 1238 struct tcp_sock *tp = tcp_sk(sk); 1239 1240 skb_queue_head_init(&tp->out_of_order_queue); 1241 tcp_init_xmit_timers(sk); 1242 tcp_prequeue_init(tp); 1243 1244 icsk->icsk_rto = TCP_TIMEOUT_INIT; 1245 tp->mdev = TCP_TIMEOUT_INIT; 1246 1247 /* So many TCP implementations out there (incorrectly) count the 1248 * initial SYN frame in their delayed-ACK and congestion control 1249 * algorithms that we must have the following bandaid to talk 1250 * efficiently to them. -DaveM 1251 */ 1252 tp->snd_cwnd = 2; 1253 1254 /* See draft-stevens-tcpca-spec-01 for discussion of the 1255 * initialization of these values. 1256 */ 1257 tp->snd_ssthresh = 0x7fffffff; /* Infinity */ 1258 tp->snd_cwnd_clamp = ~0; 1259 tp->mss_cache = 536; 1260 1261 tp->reordering = sysctl_tcp_reordering; 1262 icsk->icsk_ca_ops = &tcp_init_congestion_ops; 1263 1264 sk->sk_state = TCP_CLOSE; 1265 1266 sk->sk_write_space = sk_stream_write_space; 1267 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE); 1268 1269 icsk->icsk_af_ops = &ipv4_specific; 1270 icsk->icsk_sync_mss = tcp_sync_mss; 1271 1272 sk->sk_sndbuf = sysctl_tcp_wmem[1]; 1273 sk->sk_rcvbuf = sysctl_tcp_rmem[1]; 1274 1275 atomic_inc(&tcp_sockets_allocated); 1276 1277 return 0; 1278 } 1279 1280 int tcp_v4_destroy_sock(struct sock *sk) 1281 { 1282 struct tcp_sock *tp = tcp_sk(sk); 1283 1284 tcp_clear_xmit_timers(sk); 1285 1286 tcp_cleanup_congestion_control(sk); 1287 1288 /* Cleanup up the write buffer. */ 1289 sk_stream_writequeue_purge(sk); 1290 1291 /* Cleans up our, hopefully empty, out_of_order_queue. */ 1292 __skb_queue_purge(&tp->out_of_order_queue); 1293 1294 /* Clean prequeue, it must be empty really */ 1295 __skb_queue_purge(&tp->ucopy.prequeue); 1296 1297 /* Clean up a referenced TCP bind bucket. */ 1298 if (inet_csk(sk)->icsk_bind_hash) 1299 inet_put_port(&tcp_hashinfo, sk); 1300 1301 /* 1302 * If sendmsg cached page exists, toss it. 1303 */ 1304 if (sk->sk_sndmsg_page) { 1305 __free_page(sk->sk_sndmsg_page); 1306 sk->sk_sndmsg_page = NULL; 1307 } 1308 1309 atomic_dec(&tcp_sockets_allocated); 1310 1311 return 0; 1312 } 1313 1314 EXPORT_SYMBOL(tcp_v4_destroy_sock); 1315 1316 #ifdef CONFIG_PROC_FS 1317 /* Proc filesystem TCP sock list dumping. */ 1318 1319 static inline struct inet_timewait_sock *tw_head(struct hlist_head *head) 1320 { 1321 return hlist_empty(head) ? NULL : 1322 list_entry(head->first, struct inet_timewait_sock, tw_node); 1323 } 1324 1325 static inline struct inet_timewait_sock *tw_next(struct inet_timewait_sock *tw) 1326 { 1327 return tw->tw_node.next ? 1328 hlist_entry(tw->tw_node.next, typeof(*tw), tw_node) : NULL; 1329 } 1330 1331 static void *listening_get_next(struct seq_file *seq, void *cur) 1332 { 1333 struct inet_connection_sock *icsk; 1334 struct hlist_node *node; 1335 struct sock *sk = cur; 1336 struct tcp_iter_state* st = seq->private; 1337 1338 if (!sk) { 1339 st->bucket = 0; 1340 sk = sk_head(&tcp_hashinfo.listening_hash[0]); 1341 goto get_sk; 1342 } 1343 1344 ++st->num; 1345 1346 if (st->state == TCP_SEQ_STATE_OPENREQ) { 1347 struct request_sock *req = cur; 1348 1349 icsk = inet_csk(st->syn_wait_sk); 1350 req = req->dl_next; 1351 while (1) { 1352 while (req) { 1353 if (req->rsk_ops->family == st->family) { 1354 cur = req; 1355 goto out; 1356 } 1357 req = req->dl_next; 1358 } 1359 if (++st->sbucket >= TCP_SYNQ_HSIZE) 1360 break; 1361 get_req: 1362 req = icsk->icsk_accept_queue.listen_opt->syn_table[st->sbucket]; 1363 } 1364 sk = sk_next(st->syn_wait_sk); 1365 st->state = TCP_SEQ_STATE_LISTENING; 1366 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock); 1367 } else { 1368 icsk = inet_csk(sk); 1369 read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock); 1370 if (reqsk_queue_len(&icsk->icsk_accept_queue)) 1371 goto start_req; 1372 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock); 1373 sk = sk_next(sk); 1374 } 1375 get_sk: 1376 sk_for_each_from(sk, node) { 1377 if (sk->sk_family == st->family) { 1378 cur = sk; 1379 goto out; 1380 } 1381 icsk = inet_csk(sk); 1382 read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock); 1383 if (reqsk_queue_len(&icsk->icsk_accept_queue)) { 1384 start_req: 1385 st->uid = sock_i_uid(sk); 1386 st->syn_wait_sk = sk; 1387 st->state = TCP_SEQ_STATE_OPENREQ; 1388 st->sbucket = 0; 1389 goto get_req; 1390 } 1391 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock); 1392 } 1393 if (++st->bucket < INET_LHTABLE_SIZE) { 1394 sk = sk_head(&tcp_hashinfo.listening_hash[st->bucket]); 1395 goto get_sk; 1396 } 1397 cur = NULL; 1398 out: 1399 return cur; 1400 } 1401 1402 static void *listening_get_idx(struct seq_file *seq, loff_t *pos) 1403 { 1404 void *rc = listening_get_next(seq, NULL); 1405 1406 while (rc && *pos) { 1407 rc = listening_get_next(seq, rc); 1408 --*pos; 1409 } 1410 return rc; 1411 } 1412 1413 static void *established_get_first(struct seq_file *seq) 1414 { 1415 struct tcp_iter_state* st = seq->private; 1416 void *rc = NULL; 1417 1418 for (st->bucket = 0; st->bucket < tcp_hashinfo.ehash_size; ++st->bucket) { 1419 struct sock *sk; 1420 struct hlist_node *node; 1421 struct inet_timewait_sock *tw; 1422 1423 /* We can reschedule _before_ having picked the target: */ 1424 cond_resched_softirq(); 1425 1426 read_lock(&tcp_hashinfo.ehash[st->bucket].lock); 1427 sk_for_each(sk, node, &tcp_hashinfo.ehash[st->bucket].chain) { 1428 if (sk->sk_family != st->family) { 1429 continue; 1430 } 1431 rc = sk; 1432 goto out; 1433 } 1434 st->state = TCP_SEQ_STATE_TIME_WAIT; 1435 inet_twsk_for_each(tw, node, 1436 &tcp_hashinfo.ehash[st->bucket + tcp_hashinfo.ehash_size].chain) { 1437 if (tw->tw_family != st->family) { 1438 continue; 1439 } 1440 rc = tw; 1441 goto out; 1442 } 1443 read_unlock(&tcp_hashinfo.ehash[st->bucket].lock); 1444 st->state = TCP_SEQ_STATE_ESTABLISHED; 1445 } 1446 out: 1447 return rc; 1448 } 1449 1450 static void *established_get_next(struct seq_file *seq, void *cur) 1451 { 1452 struct sock *sk = cur; 1453 struct inet_timewait_sock *tw; 1454 struct hlist_node *node; 1455 struct tcp_iter_state* st = seq->private; 1456 1457 ++st->num; 1458 1459 if (st->state == TCP_SEQ_STATE_TIME_WAIT) { 1460 tw = cur; 1461 tw = tw_next(tw); 1462 get_tw: 1463 while (tw && tw->tw_family != st->family) { 1464 tw = tw_next(tw); 1465 } 1466 if (tw) { 1467 cur = tw; 1468 goto out; 1469 } 1470 read_unlock(&tcp_hashinfo.ehash[st->bucket].lock); 1471 st->state = TCP_SEQ_STATE_ESTABLISHED; 1472 1473 /* We can reschedule between buckets: */ 1474 cond_resched_softirq(); 1475 1476 if (++st->bucket < tcp_hashinfo.ehash_size) { 1477 read_lock(&tcp_hashinfo.ehash[st->bucket].lock); 1478 sk = sk_head(&tcp_hashinfo.ehash[st->bucket].chain); 1479 } else { 1480 cur = NULL; 1481 goto out; 1482 } 1483 } else 1484 sk = sk_next(sk); 1485 1486 sk_for_each_from(sk, node) { 1487 if (sk->sk_family == st->family) 1488 goto found; 1489 } 1490 1491 st->state = TCP_SEQ_STATE_TIME_WAIT; 1492 tw = tw_head(&tcp_hashinfo.ehash[st->bucket + tcp_hashinfo.ehash_size].chain); 1493 goto get_tw; 1494 found: 1495 cur = sk; 1496 out: 1497 return cur; 1498 } 1499 1500 static void *established_get_idx(struct seq_file *seq, loff_t pos) 1501 { 1502 void *rc = established_get_first(seq); 1503 1504 while (rc && pos) { 1505 rc = established_get_next(seq, rc); 1506 --pos; 1507 } 1508 return rc; 1509 } 1510 1511 static void *tcp_get_idx(struct seq_file *seq, loff_t pos) 1512 { 1513 void *rc; 1514 struct tcp_iter_state* st = seq->private; 1515 1516 inet_listen_lock(&tcp_hashinfo); 1517 st->state = TCP_SEQ_STATE_LISTENING; 1518 rc = listening_get_idx(seq, &pos); 1519 1520 if (!rc) { 1521 inet_listen_unlock(&tcp_hashinfo); 1522 local_bh_disable(); 1523 st->state = TCP_SEQ_STATE_ESTABLISHED; 1524 rc = established_get_idx(seq, pos); 1525 } 1526 1527 return rc; 1528 } 1529 1530 static void *tcp_seq_start(struct seq_file *seq, loff_t *pos) 1531 { 1532 struct tcp_iter_state* st = seq->private; 1533 st->state = TCP_SEQ_STATE_LISTENING; 1534 st->num = 0; 1535 return *pos ? tcp_get_idx(seq, *pos - 1) : SEQ_START_TOKEN; 1536 } 1537 1538 static void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos) 1539 { 1540 void *rc = NULL; 1541 struct tcp_iter_state* st; 1542 1543 if (v == SEQ_START_TOKEN) { 1544 rc = tcp_get_idx(seq, 0); 1545 goto out; 1546 } 1547 st = seq->private; 1548 1549 switch (st->state) { 1550 case TCP_SEQ_STATE_OPENREQ: 1551 case TCP_SEQ_STATE_LISTENING: 1552 rc = listening_get_next(seq, v); 1553 if (!rc) { 1554 inet_listen_unlock(&tcp_hashinfo); 1555 local_bh_disable(); 1556 st->state = TCP_SEQ_STATE_ESTABLISHED; 1557 rc = established_get_first(seq); 1558 } 1559 break; 1560 case TCP_SEQ_STATE_ESTABLISHED: 1561 case TCP_SEQ_STATE_TIME_WAIT: 1562 rc = established_get_next(seq, v); 1563 break; 1564 } 1565 out: 1566 ++*pos; 1567 return rc; 1568 } 1569 1570 static void tcp_seq_stop(struct seq_file *seq, void *v) 1571 { 1572 struct tcp_iter_state* st = seq->private; 1573 1574 switch (st->state) { 1575 case TCP_SEQ_STATE_OPENREQ: 1576 if (v) { 1577 struct inet_connection_sock *icsk = inet_csk(st->syn_wait_sk); 1578 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock); 1579 } 1580 case TCP_SEQ_STATE_LISTENING: 1581 if (v != SEQ_START_TOKEN) 1582 inet_listen_unlock(&tcp_hashinfo); 1583 break; 1584 case TCP_SEQ_STATE_TIME_WAIT: 1585 case TCP_SEQ_STATE_ESTABLISHED: 1586 if (v) 1587 read_unlock(&tcp_hashinfo.ehash[st->bucket].lock); 1588 local_bh_enable(); 1589 break; 1590 } 1591 } 1592 1593 static int tcp_seq_open(struct inode *inode, struct file *file) 1594 { 1595 struct tcp_seq_afinfo *afinfo = PDE(inode)->data; 1596 struct seq_file *seq; 1597 struct tcp_iter_state *s; 1598 int rc; 1599 1600 if (unlikely(afinfo == NULL)) 1601 return -EINVAL; 1602 1603 s = kmalloc(sizeof(*s), GFP_KERNEL); 1604 if (!s) 1605 return -ENOMEM; 1606 memset(s, 0, sizeof(*s)); 1607 s->family = afinfo->family; 1608 s->seq_ops.start = tcp_seq_start; 1609 s->seq_ops.next = tcp_seq_next; 1610 s->seq_ops.show = afinfo->seq_show; 1611 s->seq_ops.stop = tcp_seq_stop; 1612 1613 rc = seq_open(file, &s->seq_ops); 1614 if (rc) 1615 goto out_kfree; 1616 seq = file->private_data; 1617 seq->private = s; 1618 out: 1619 return rc; 1620 out_kfree: 1621 kfree(s); 1622 goto out; 1623 } 1624 1625 int tcp_proc_register(struct tcp_seq_afinfo *afinfo) 1626 { 1627 int rc = 0; 1628 struct proc_dir_entry *p; 1629 1630 if (!afinfo) 1631 return -EINVAL; 1632 afinfo->seq_fops->owner = afinfo->owner; 1633 afinfo->seq_fops->open = tcp_seq_open; 1634 afinfo->seq_fops->read = seq_read; 1635 afinfo->seq_fops->llseek = seq_lseek; 1636 afinfo->seq_fops->release = seq_release_private; 1637 1638 p = proc_net_fops_create(afinfo->name, S_IRUGO, afinfo->seq_fops); 1639 if (p) 1640 p->data = afinfo; 1641 else 1642 rc = -ENOMEM; 1643 return rc; 1644 } 1645 1646 void tcp_proc_unregister(struct tcp_seq_afinfo *afinfo) 1647 { 1648 if (!afinfo) 1649 return; 1650 proc_net_remove(afinfo->name); 1651 memset(afinfo->seq_fops, 0, sizeof(*afinfo->seq_fops)); 1652 } 1653 1654 static void get_openreq4(struct sock *sk, struct request_sock *req, 1655 char *tmpbuf, int i, int uid) 1656 { 1657 const struct inet_request_sock *ireq = inet_rsk(req); 1658 int ttd = req->expires - jiffies; 1659 1660 sprintf(tmpbuf, "%4d: %08X:%04X %08X:%04X" 1661 " %02X %08X:%08X %02X:%08lX %08X %5d %8d %u %d %p", 1662 i, 1663 ireq->loc_addr, 1664 ntohs(inet_sk(sk)->sport), 1665 ireq->rmt_addr, 1666 ntohs(ireq->rmt_port), 1667 TCP_SYN_RECV, 1668 0, 0, /* could print option size, but that is af dependent. */ 1669 1, /* timers active (only the expire timer) */ 1670 jiffies_to_clock_t(ttd), 1671 req->retrans, 1672 uid, 1673 0, /* non standard timer */ 1674 0, /* open_requests have no inode */ 1675 atomic_read(&sk->sk_refcnt), 1676 req); 1677 } 1678 1679 static void get_tcp4_sock(struct sock *sp, char *tmpbuf, int i) 1680 { 1681 int timer_active; 1682 unsigned long timer_expires; 1683 struct tcp_sock *tp = tcp_sk(sp); 1684 const struct inet_connection_sock *icsk = inet_csk(sp); 1685 struct inet_sock *inet = inet_sk(sp); 1686 unsigned int dest = inet->daddr; 1687 unsigned int src = inet->rcv_saddr; 1688 __u16 destp = ntohs(inet->dport); 1689 __u16 srcp = ntohs(inet->sport); 1690 1691 if (icsk->icsk_pending == ICSK_TIME_RETRANS) { 1692 timer_active = 1; 1693 timer_expires = icsk->icsk_timeout; 1694 } else if (icsk->icsk_pending == ICSK_TIME_PROBE0) { 1695 timer_active = 4; 1696 timer_expires = icsk->icsk_timeout; 1697 } else if (timer_pending(&sp->sk_timer)) { 1698 timer_active = 2; 1699 timer_expires = sp->sk_timer.expires; 1700 } else { 1701 timer_active = 0; 1702 timer_expires = jiffies; 1703 } 1704 1705 sprintf(tmpbuf, "%4d: %08X:%04X %08X:%04X %02X %08X:%08X %02X:%08lX " 1706 "%08X %5d %8d %lu %d %p %u %u %u %u %d", 1707 i, src, srcp, dest, destp, sp->sk_state, 1708 tp->write_seq - tp->snd_una, tp->rcv_nxt - tp->copied_seq, 1709 timer_active, 1710 jiffies_to_clock_t(timer_expires - jiffies), 1711 icsk->icsk_retransmits, 1712 sock_i_uid(sp), 1713 icsk->icsk_probes_out, 1714 sock_i_ino(sp), 1715 atomic_read(&sp->sk_refcnt), sp, 1716 icsk->icsk_rto, 1717 icsk->icsk_ack.ato, 1718 (icsk->icsk_ack.quick << 1) | icsk->icsk_ack.pingpong, 1719 tp->snd_cwnd, 1720 tp->snd_ssthresh >= 0xFFFF ? -1 : tp->snd_ssthresh); 1721 } 1722 1723 static void get_timewait4_sock(struct inet_timewait_sock *tw, char *tmpbuf, int i) 1724 { 1725 unsigned int dest, src; 1726 __u16 destp, srcp; 1727 int ttd = tw->tw_ttd - jiffies; 1728 1729 if (ttd < 0) 1730 ttd = 0; 1731 1732 dest = tw->tw_daddr; 1733 src = tw->tw_rcv_saddr; 1734 destp = ntohs(tw->tw_dport); 1735 srcp = ntohs(tw->tw_sport); 1736 1737 sprintf(tmpbuf, "%4d: %08X:%04X %08X:%04X" 1738 " %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %p", 1739 i, src, srcp, dest, destp, tw->tw_substate, 0, 0, 1740 3, jiffies_to_clock_t(ttd), 0, 0, 0, 0, 1741 atomic_read(&tw->tw_refcnt), tw); 1742 } 1743 1744 #define TMPSZ 150 1745 1746 static int tcp4_seq_show(struct seq_file *seq, void *v) 1747 { 1748 struct tcp_iter_state* st; 1749 char tmpbuf[TMPSZ + 1]; 1750 1751 if (v == SEQ_START_TOKEN) { 1752 seq_printf(seq, "%-*s\n", TMPSZ - 1, 1753 " sl local_address rem_address st tx_queue " 1754 "rx_queue tr tm->when retrnsmt uid timeout " 1755 "inode"); 1756 goto out; 1757 } 1758 st = seq->private; 1759 1760 switch (st->state) { 1761 case TCP_SEQ_STATE_LISTENING: 1762 case TCP_SEQ_STATE_ESTABLISHED: 1763 get_tcp4_sock(v, tmpbuf, st->num); 1764 break; 1765 case TCP_SEQ_STATE_OPENREQ: 1766 get_openreq4(st->syn_wait_sk, v, tmpbuf, st->num, st->uid); 1767 break; 1768 case TCP_SEQ_STATE_TIME_WAIT: 1769 get_timewait4_sock(v, tmpbuf, st->num); 1770 break; 1771 } 1772 seq_printf(seq, "%-*s\n", TMPSZ - 1, tmpbuf); 1773 out: 1774 return 0; 1775 } 1776 1777 static struct file_operations tcp4_seq_fops; 1778 static struct tcp_seq_afinfo tcp4_seq_afinfo = { 1779 .owner = THIS_MODULE, 1780 .name = "tcp", 1781 .family = AF_INET, 1782 .seq_show = tcp4_seq_show, 1783 .seq_fops = &tcp4_seq_fops, 1784 }; 1785 1786 int __init tcp4_proc_init(void) 1787 { 1788 return tcp_proc_register(&tcp4_seq_afinfo); 1789 } 1790 1791 void tcp4_proc_exit(void) 1792 { 1793 tcp_proc_unregister(&tcp4_seq_afinfo); 1794 } 1795 #endif /* CONFIG_PROC_FS */ 1796 1797 struct proto tcp_prot = { 1798 .name = "TCP", 1799 .owner = THIS_MODULE, 1800 .close = tcp_close, 1801 .connect = tcp_v4_connect, 1802 .disconnect = tcp_disconnect, 1803 .accept = inet_csk_accept, 1804 .ioctl = tcp_ioctl, 1805 .init = tcp_v4_init_sock, 1806 .destroy = tcp_v4_destroy_sock, 1807 .shutdown = tcp_shutdown, 1808 .setsockopt = tcp_setsockopt, 1809 .getsockopt = tcp_getsockopt, 1810 .sendmsg = tcp_sendmsg, 1811 .recvmsg = tcp_recvmsg, 1812 .backlog_rcv = tcp_v4_do_rcv, 1813 .hash = tcp_v4_hash, 1814 .unhash = tcp_unhash, 1815 .get_port = tcp_v4_get_port, 1816 .enter_memory_pressure = tcp_enter_memory_pressure, 1817 .sockets_allocated = &tcp_sockets_allocated, 1818 .orphan_count = &tcp_orphan_count, 1819 .memory_allocated = &tcp_memory_allocated, 1820 .memory_pressure = &tcp_memory_pressure, 1821 .sysctl_mem = sysctl_tcp_mem, 1822 .sysctl_wmem = sysctl_tcp_wmem, 1823 .sysctl_rmem = sysctl_tcp_rmem, 1824 .max_header = MAX_TCP_HEADER, 1825 .obj_size = sizeof(struct tcp_sock), 1826 .twsk_prot = &tcp_timewait_sock_ops, 1827 .rsk_prot = &tcp_request_sock_ops, 1828 }; 1829 1830 1831 1832 void __init tcp_v4_init(struct net_proto_family *ops) 1833 { 1834 int err = sock_create_kern(PF_INET, SOCK_RAW, IPPROTO_TCP, &tcp_socket); 1835 if (err < 0) 1836 panic("Failed to create the TCP control socket.\n"); 1837 tcp_socket->sk->sk_allocation = GFP_ATOMIC; 1838 inet_sk(tcp_socket->sk)->uc_ttl = -1; 1839 1840 /* Unhash it so that IP input processing does not even 1841 * see it, we do not wish this socket to see incoming 1842 * packets. 1843 */ 1844 tcp_socket->sk->sk_prot->unhash(tcp_socket->sk); 1845 } 1846 1847 EXPORT_SYMBOL(ipv4_specific); 1848 EXPORT_SYMBOL(tcp_hashinfo); 1849 EXPORT_SYMBOL(tcp_prot); 1850 EXPORT_SYMBOL(tcp_unhash); 1851 EXPORT_SYMBOL(tcp_v4_conn_request); 1852 EXPORT_SYMBOL(tcp_v4_connect); 1853 EXPORT_SYMBOL(tcp_v4_do_rcv); 1854 EXPORT_SYMBOL(tcp_v4_remember_stamp); 1855 EXPORT_SYMBOL(tcp_v4_send_check); 1856 EXPORT_SYMBOL(tcp_v4_syn_recv_sock); 1857 1858 #ifdef CONFIG_PROC_FS 1859 EXPORT_SYMBOL(tcp_proc_register); 1860 EXPORT_SYMBOL(tcp_proc_unregister); 1861 #endif 1862 EXPORT_SYMBOL(sysctl_local_port_range); 1863 EXPORT_SYMBOL(sysctl_tcp_low_latency); 1864 EXPORT_SYMBOL(sysctl_tcp_tw_reuse); 1865 1866