1/*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 * 31 * @(#)tcp_subr.c 8.2 (Berkeley) 5/24/95 32 */ 33 34#include <sys/cdefs.h> 35__FBSDID("$FreeBSD$"); 36 37#include "opt_inet.h" 38#include "opt_inet6.h" 39#include "opt_tcpdebug.h" 40 41#include <sys/param.h> 42#include <sys/systm.h> 43#include <sys/callout.h> 44#include <sys/kernel.h> 45#include <sys/sysctl.h> 46#include <sys/malloc.h> 47#include <sys/mbuf.h> 48#include <sys/priv.h> 49#include <sys/proc.h> 50#include <sys/socket.h> 51#include <sys/socketvar.h> 52#ifndef INVARIANTS 53#include <sys/syslog.h> 54#endif 55#include <sys/protosw.h> 56#include <sys/random.h> 57 58#include <vm/uma.h> 59 60#include <net/route.h> 61#include <net/if.h> 62#include <net/if_var.h> 63#include <net/vnet.h> 64 65#include <netinet/in.h> 66#include <netinet/in_kdtrace.h> 67#include <netinet/in_pcb.h> 68#include <netinet/in_systm.h> 69#include <netinet/in_var.h> 70#include <netinet/ip.h> 71#include <netinet/ip_icmp.h> 72#include <netinet/ip_var.h> 73#ifdef INET6 74#include <netinet/ip6.h> 75#include <netinet6/in6_pcb.h> 76#include <netinet6/ip6_var.h> 77#include <netinet6/scope6_var.h> 78#include <netinet6/nd6.h> 79#endif 80#include <netinet/tcp.h> 81#include <netinet/tcp_fsm.h> 82#include <netinet/tcp_seq.h> 83#include <netinet/tcp_timer.h> 84#include <netinet/tcp_var.h> 85#ifdef INET6 86#include <netinet6/tcp6_var.h> 87#endif 88#include <netinet/tcpip.h> 89#ifdef TCPDEBUG 90#include <netinet/tcp_debug.h> 91#endif 92#ifdef INET6 93#include <netinet6/ip6protosw.h> 94#endif 95 96#include <netinet/udp.h> 97#include <netinet/udp_var.h> 98#include <machine/in_cksum.h> 99 100#include <security/mac/mac_framework.h> 101 102VNET_DEFINE_STATIC(uma_zone_t, tcptw_zone); 103#define V_tcptw_zone VNET(tcptw_zone) 104static int maxtcptw; 105 106/* 107 * The timed wait queue contains references to each of the TCP sessions 108 * currently in the TIME_WAIT state. The queue pointers, including the 109 * queue pointers in each tcptw structure, are protected using the global 110 * timewait lock, which must be held over queue iteration and modification. 111 * 112 * Rules on tcptw usage: 113 * - a inpcb is always freed _after_ its tcptw 114 * - a tcptw relies on its inpcb reference counting for memory stability 115 * - a tcptw is dereferenceable only while its inpcb is locked 116 */ 117VNET_DEFINE_STATIC(TAILQ_HEAD(, tcptw), twq_2msl); 118#define V_twq_2msl VNET(twq_2msl) 119 120/* Global timewait lock */ 121VNET_DEFINE_STATIC(struct rwlock, tw_lock); 122#define V_tw_lock VNET(tw_lock) 123 124#define TW_LOCK_INIT(tw, d) rw_init_flags(&(tw), (d), 0) 125#define TW_LOCK_DESTROY(tw) rw_destroy(&(tw)) 126#define TW_RLOCK(tw) rw_rlock(&(tw)) 127#define TW_WLOCK(tw) rw_wlock(&(tw)) 128#define TW_RUNLOCK(tw) rw_runlock(&(tw)) 129#define TW_WUNLOCK(tw) rw_wunlock(&(tw)) 130#define TW_LOCK_ASSERT(tw) rw_assert(&(tw), RA_LOCKED) 131#define TW_RLOCK_ASSERT(tw) rw_assert(&(tw), RA_RLOCKED) 132#define TW_WLOCK_ASSERT(tw) rw_assert(&(tw), RA_WLOCKED) 133#define TW_UNLOCK_ASSERT(tw) rw_assert(&(tw), RA_UNLOCKED) 134 135static void tcp_tw_2msl_reset(struct tcptw *, int); 136static void tcp_tw_2msl_stop(struct tcptw *, int); 137static int tcp_twrespond(struct tcptw *, int); 138 139static int 140tcptw_auto_size(void) 141{ 142 int halfrange; 143 144 /* 145 * Max out at half the ephemeral port range so that TIME_WAIT 146 * sockets don't tie up too many ephemeral ports. 147 */ 148 if (V_ipport_lastauto > V_ipport_firstauto) 149 halfrange = (V_ipport_lastauto - V_ipport_firstauto) / 2; 150 else 151 halfrange = (V_ipport_firstauto - V_ipport_lastauto) / 2; 152 /* Protect against goofy port ranges smaller than 32. */ 153 return (imin(imax(halfrange, 32), maxsockets / 5)); 154} 155 156static int 157sysctl_maxtcptw(SYSCTL_HANDLER_ARGS) 158{ 159 int error, new; 160 161 if (maxtcptw == 0) 162 new = tcptw_auto_size(); 163 else 164 new = maxtcptw; 165 error = sysctl_handle_int(oidp, &new, 0, req); 166 if (error == 0 && req->newptr) 167 if (new >= 32) { 168 maxtcptw = new; 169 uma_zone_set_max(V_tcptw_zone, maxtcptw); 170 } 171 return (error); 172} 173 174SYSCTL_PROC(_net_inet_tcp, OID_AUTO, maxtcptw, 175 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 176 &maxtcptw, 0, sysctl_maxtcptw, "IU", 177 "Maximum number of compressed TCP TIME_WAIT entries"); 178 179VNET_DEFINE_STATIC(int, nolocaltimewait) = 0; 180#define V_nolocaltimewait VNET(nolocaltimewait) 181SYSCTL_INT(_net_inet_tcp, OID_AUTO, nolocaltimewait, CTLFLAG_VNET | CTLFLAG_RW, 182 &VNET_NAME(nolocaltimewait), 0, 183 "Do not create compressed TCP TIME_WAIT entries for local connections"); 184 185void 186tcp_tw_zone_change(void) 187{ 188 189 if (maxtcptw == 0) 190 uma_zone_set_max(V_tcptw_zone, tcptw_auto_size()); 191} 192 193void 194tcp_tw_init(void) 195{ 196 197 V_tcptw_zone = uma_zcreate("tcptw", sizeof(struct tcptw), 198 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 199 TUNABLE_INT_FETCH("net.inet.tcp.maxtcptw", &maxtcptw); 200 if (maxtcptw == 0) 201 uma_zone_set_max(V_tcptw_zone, tcptw_auto_size()); 202 else 203 uma_zone_set_max(V_tcptw_zone, maxtcptw); 204 TAILQ_INIT(&V_twq_2msl); 205 TW_LOCK_INIT(V_tw_lock, "tcptw"); 206} 207 208#ifdef VIMAGE 209void 210tcp_tw_destroy(void) 211{ 212 struct tcptw *tw; 213 struct epoch_tracker et; 214 215 NET_EPOCH_ENTER(et); 216 while ((tw = TAILQ_FIRST(&V_twq_2msl)) != NULL) 217 tcp_twclose(tw, 0); 218 NET_EPOCH_EXIT(et); 219 220 TW_LOCK_DESTROY(V_tw_lock); 221 uma_zdestroy(V_tcptw_zone); 222} 223#endif 224 225/* 226 * Move a TCP connection into TIME_WAIT state. 227 * tcbinfo is locked. 228 * inp is locked, and is unlocked before returning. 229 */ 230void 231tcp_twstart(struct tcpcb *tp) 232{ 233 struct tcptw twlocal, *tw; 234 struct inpcb *inp = tp->t_inpcb; 235 struct socket *so; 236 uint32_t recwin; 237 bool acknow, local; 238#ifdef INET6 239 bool isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6; 240#endif 241 242 NET_EPOCH_ASSERT(); 243 INP_WLOCK_ASSERT(inp); 244 245 /* A dropped inp should never transition to TIME_WAIT state. */ 246 KASSERT((inp->inp_flags & INP_DROPPED) == 0, ("tcp_twstart: " 247 "(inp->inp_flags & INP_DROPPED) != 0")); 248 249 if (V_nolocaltimewait) { 250#ifdef INET6 251 if (isipv6) 252 local = in6_localaddr(&inp->in6p_faddr); 253 else 254#endif 255#ifdef INET 256 local = in_localip(inp->inp_faddr); 257#else 258 local = false; 259#endif 260 } else 261 local = false; 262 263 /* 264 * For use only by DTrace. We do not reference the state 265 * after this point so modifying it in place is not a problem. 266 */ 267 tcp_state_change(tp, TCPS_TIME_WAIT); 268 269 if (local) 270 tw = &twlocal; 271 else 272 tw = uma_zalloc(V_tcptw_zone, M_NOWAIT); 273 if (tw == NULL) { 274 /* 275 * Reached limit on total number of TIMEWAIT connections 276 * allowed. Remove a connection from TIMEWAIT queue in LRU 277 * fashion to make room for this connection. 278 * 279 * XXX: Check if it possible to always have enough room 280 * in advance based on guarantees provided by uma_zalloc(). 281 */ 282 tw = tcp_tw_2msl_scan(1); 283 if (tw == NULL) { 284 tp = tcp_close(tp); 285 if (tp != NULL) 286 INP_WUNLOCK(inp); 287 return; 288 } 289 } 290 /* 291 * For !local case the tcptw will hold a reference on its inpcb 292 * until tcp_twclose is called. 293 */ 294 tw->tw_inpcb = inp; 295 296 /* 297 * Recover last window size sent. 298 */ 299 so = inp->inp_socket; 300 recwin = lmin(lmax(sbspace(&so->so_rcv), 0), 301 (long)TCP_MAXWIN << tp->rcv_scale); 302 if (recwin < (so->so_rcv.sb_hiwat / 4) && 303 recwin < tp->t_maxseg) 304 recwin = 0; 305 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt) && 306 recwin < (tp->rcv_adv - tp->rcv_nxt)) 307 recwin = (tp->rcv_adv - tp->rcv_nxt); 308 tw->last_win = (u_short)(recwin >> tp->rcv_scale); 309 310 /* 311 * Set t_recent if timestamps are used on the connection. 312 */ 313 if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) == 314 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) { 315 tw->t_recent = tp->ts_recent; 316 tw->ts_offset = tp->ts_offset; 317 } else { 318 tw->t_recent = 0; 319 tw->ts_offset = 0; 320 } 321 322 tw->snd_nxt = tp->snd_nxt; 323 tw->t_port = tp->t_port; 324 tw->rcv_nxt = tp->rcv_nxt; 325 tw->iss = tp->iss; 326 tw->irs = tp->irs; 327 tw->t_starttime = tp->t_starttime; 328 tw->tw_time = 0; 329 330/* XXX 331 * If this code will 332 * be used for fin-wait-2 state also, then we may need 333 * a ts_recent from the last segment. 334 */ 335 acknow = tp->t_flags & TF_ACKNOW; 336 337 /* 338 * First, discard tcpcb state, which includes stopping its timers and 339 * freeing it. tcp_discardcb() used to also release the inpcb, but 340 * that work is now done in the caller. 341 * 342 * Note: soisdisconnected() call used to be made in tcp_discardcb(), 343 * and might not be needed here any longer. 344 */ 345 tcp_discardcb(tp); 346 soisdisconnected(so); 347 tw->tw_so_options = so->so_options; 348 inp->inp_flags |= INP_TIMEWAIT; 349 if (acknow) 350 tcp_twrespond(tw, TH_ACK); 351 if (local) 352 in_pcbdrop(inp); 353 else { 354 in_pcbref(inp); /* Reference from tw */ 355 tw->tw_cred = crhold(so->so_cred); 356 inp->inp_ppcb = tw; 357 TCPSTATES_INC(TCPS_TIME_WAIT); 358 tcp_tw_2msl_reset(tw, 0); 359 } 360 361 /* 362 * If the inpcb owns the sole reference to the socket, then we can 363 * detach and free the socket as it is not needed in time wait. 364 */ 365 if (inp->inp_flags & INP_SOCKREF) { 366 KASSERT(so->so_state & SS_PROTOREF, 367 ("tcp_twstart: !SS_PROTOREF")); 368 inp->inp_flags &= ~INP_SOCKREF; 369 INP_WUNLOCK(inp); 370 SOCK_LOCK(so); 371 so->so_state &= ~SS_PROTOREF; 372 sofree(so); 373 } else 374 INP_WUNLOCK(inp); 375} 376 377/* 378 * Returns 1 if the TIME_WAIT state was killed and we should start over, 379 * looking for a pcb in the listen state. Returns 0 otherwise. 380 * It be called with to == NULL only for pure SYN-segments. 381 */ 382int 383tcp_twcheck(struct inpcb *inp, struct tcpopt *to, struct tcphdr *th, 384 struct mbuf *m, int tlen) 385{ 386 struct tcptw *tw; 387 int thflags; 388 tcp_seq seq; 389 390 NET_EPOCH_ASSERT(); 391 INP_WLOCK_ASSERT(inp); 392 393 /* 394 * XXXRW: Time wait state for inpcb has been recycled, but inpcb is 395 * still present. This is undesirable, but temporarily necessary 396 * until we work out how to handle inpcb's who's timewait state has 397 * been removed. 398 */ 399 tw = intotw(inp); 400 if (tw == NULL) 401 goto drop; 402 403 thflags = th->th_flags; 404 KASSERT(to != NULL || (thflags & (TH_SYN | TH_ACK)) == TH_SYN, 405 ("tcp_twcheck: called without options on a non-SYN segment")); 406 407 /* 408 * NOTE: for FIN_WAIT_2 (to be added later), 409 * must validate sequence number before accepting RST 410 */ 411 412 /* 413 * If the segment contains RST: 414 * Drop the segment - see Stevens, vol. 2, p. 964 and 415 * RFC 1337. 416 */ 417 if (thflags & TH_RST) 418 goto drop; 419 420#if 0 421/* PAWS not needed at the moment */ 422 /* 423 * RFC 1323 PAWS: If we have a timestamp reply on this segment 424 * and it's less than ts_recent, drop it. 425 */ 426 if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent && 427 TSTMP_LT(to.to_tsval, tp->ts_recent)) { 428 if ((thflags & TH_ACK) == 0) 429 goto drop; 430 goto ack; 431 } 432 /* 433 * ts_recent is never updated because we never accept new segments. 434 */ 435#endif 436 437 /* 438 * If a new connection request is received 439 * while in TIME_WAIT, drop the old connection 440 * and start over if the sequence numbers 441 * are above the previous ones. 442 * Allow UDP port number changes in this case. 443 */ 444 if ((thflags & TH_SYN) && SEQ_GT(th->th_seq, tw->rcv_nxt)) { 445 tcp_twclose(tw, 0); 446 return (1); 447 } 448 449 /* 450 * Send RST if UDP port numbers don't match 451 */ 452 if (tw->t_port != m->m_pkthdr.tcp_tun_port) { 453 if (th->th_flags & TH_ACK) { 454 tcp_respond(NULL, mtod(m, void *), th, m, 455 (tcp_seq)0, th->th_ack, TH_RST); 456 } else { 457 if (th->th_flags & TH_SYN) 458 tlen++; 459 if (th->th_flags & TH_FIN) 460 tlen++; 461 tcp_respond(NULL, mtod(m, void *), th, m, 462 th->th_seq+tlen, (tcp_seq)0, TH_RST|TH_ACK); 463 } 464 INP_WUNLOCK(inp); 465 return (0); 466 } 467 468 /* 469 * Drop the segment if it does not contain an ACK. 470 */ 471 if ((thflags & TH_ACK) == 0) 472 goto drop; 473 474 /* 475 * If timestamps were negotiated during SYN/ACK and a 476 * segment without a timestamp is received, silently drop 477 * the segment, unless the missing timestamps are tolerated. 478 * See section 3.2 of RFC 7323. 479 */ 480 if (((to->to_flags & TOF_TS) == 0) && (tw->t_recent != 0) && 481 (V_tcp_tolerate_missing_ts == 0)) { 482 goto drop; 483 } 484 485 /* 486 * Reset the 2MSL timer if this is a duplicate FIN. 487 */ 488 if (thflags & TH_FIN) { 489 seq = th->th_seq + tlen + (thflags & TH_SYN ? 1 : 0); 490 if (seq + 1 == tw->rcv_nxt) 491 tcp_tw_2msl_reset(tw, 1); 492 } 493 494 /* 495 * Acknowledge the segment if it has data or is not a duplicate ACK. 496 */ 497 if (thflags != TH_ACK || tlen != 0 || 498 th->th_seq != tw->rcv_nxt || th->th_ack != tw->snd_nxt) { 499 TCP_PROBE5(receive, NULL, NULL, m, NULL, th); 500 tcp_twrespond(tw, TH_ACK); 501 goto dropnoprobe; 502 } 503drop: 504 TCP_PROBE5(receive, NULL, NULL, m, NULL, th); 505dropnoprobe: 506 INP_WUNLOCK(inp); 507 m_freem(m); 508 return (0); 509} 510 511void 512tcp_twclose(struct tcptw *tw, int reuse) 513{ 514 struct socket *so; 515 struct inpcb *inp; 516 517 /* 518 * At this point, we are in one of two situations: 519 * 520 * (1) We have no socket, just an inpcb<->twtcp pair. We can free 521 * all state. 522 * 523 * (2) We have a socket -- if we own a reference, release it and 524 * notify the socket layer. 525 */ 526 inp = tw->tw_inpcb; 527 KASSERT((inp->inp_flags & INP_TIMEWAIT), ("tcp_twclose: !timewait")); 528 KASSERT(intotw(inp) == tw, ("tcp_twclose: inp_ppcb != tw")); 529 NET_EPOCH_ASSERT(); 530 INP_WLOCK_ASSERT(inp); 531 532 tcp_tw_2msl_stop(tw, reuse); 533 inp->inp_ppcb = NULL; 534 in_pcbdrop(inp); 535 536 so = inp->inp_socket; 537 if (so != NULL) { 538 /* 539 * If there's a socket, handle two cases: first, we own a 540 * strong reference, which we will now release, or we don't 541 * in which case another reference exists (XXXRW: think 542 * about this more), and we don't need to take action. 543 */ 544 if (inp->inp_flags & INP_SOCKREF) { 545 inp->inp_flags &= ~INP_SOCKREF; 546 INP_WUNLOCK(inp); 547 SOCK_LOCK(so); 548 KASSERT(so->so_state & SS_PROTOREF, 549 ("tcp_twclose: INP_SOCKREF && !SS_PROTOREF")); 550 so->so_state &= ~SS_PROTOREF; 551 sofree(so); 552 } else { 553 /* 554 * If we don't own the only reference, the socket and 555 * inpcb need to be left around to be handled by 556 * tcp_usr_detach() later. 557 */ 558 INP_WUNLOCK(inp); 559 } 560 } else { 561 /* 562 * The socket has been already cleaned-up for us, only free the 563 * inpcb. 564 */ 565 in_pcbfree(inp); 566 } 567 TCPSTAT_INC(tcps_closed); 568} 569 570static int 571tcp_twrespond(struct tcptw *tw, int flags) 572{ 573 struct inpcb *inp = tw->tw_inpcb; 574#if defined(INET6) || defined(INET) 575 struct tcphdr *th = NULL; 576#endif 577 struct mbuf *m; 578#ifdef INET 579 struct ip *ip = NULL; 580#endif 581 u_int hdrlen, optlen, ulen; 582 int error = 0; /* Keep compiler happy */ 583 struct tcpopt to; 584#ifdef INET6 585 struct ip6_hdr *ip6 = NULL; 586 int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6; 587#endif 588 struct udphdr *udp = NULL; 589 hdrlen = 0; /* Keep compiler happy */ 590 591 INP_WLOCK_ASSERT(inp); 592 593 m = m_gethdr(M_NOWAIT, MT_DATA); 594 if (m == NULL) 595 return (ENOBUFS); 596 m->m_data += max_linkhdr; 597 598#ifdef MAC 599 mac_inpcb_create_mbuf(inp, m); 600#endif 601 602#ifdef INET6 603 if (isipv6) { 604 hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 605 ip6 = mtod(m, struct ip6_hdr *); 606 if (tw->t_port) { 607 udp = (struct udphdr *)(ip6 + 1); 608 hdrlen += sizeof(struct udphdr); 609 udp->uh_sport = htons(V_tcp_udp_tunneling_port); 610 udp->uh_dport = tw->t_port; 611 ulen = (hdrlen - sizeof(struct ip6_hdr)); 612 th = (struct tcphdr *)(udp + 1); 613 } else 614 th = (struct tcphdr *)(ip6 + 1); 615 tcpip_fillheaders(inp, tw->t_port, ip6, th); 616 } 617#endif 618#if defined(INET6) && defined(INET) 619 else 620#endif 621#ifdef INET 622 { 623 hdrlen = sizeof(struct tcpiphdr); 624 ip = mtod(m, struct ip *); 625 if (tw->t_port) { 626 udp = (struct udphdr *)(ip + 1); 627 hdrlen += sizeof(struct udphdr); 628 udp->uh_sport = htons(V_tcp_udp_tunneling_port); 629 udp->uh_dport = tw->t_port; 630 ulen = (hdrlen - sizeof(struct ip)); 631 th = (struct tcphdr *)(udp + 1); 632 } else 633 th = (struct tcphdr *)(ip + 1); 634 tcpip_fillheaders(inp, tw->t_port, ip, th); 635 } 636#endif 637 to.to_flags = 0; 638 639 /* 640 * Send a timestamp and echo-reply if both our side and our peer 641 * have sent timestamps in our SYN's and this is not a RST. 642 */ 643 if (tw->t_recent && flags == TH_ACK) { 644 to.to_flags |= TOF_TS; 645 to.to_tsval = tcp_ts_getticks() + tw->ts_offset; 646 to.to_tsecr = tw->t_recent; 647 } 648 optlen = tcp_addoptions(&to, (u_char *)(th + 1)); 649 650 if (udp) { 651 ulen += optlen; 652 udp->uh_ulen = htons(ulen); 653 } 654 m->m_len = hdrlen + optlen; 655 m->m_pkthdr.len = m->m_len; 656 657 KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small")); 658 659 th->th_seq = htonl(tw->snd_nxt); 660 th->th_ack = htonl(tw->rcv_nxt); 661 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 662 th->th_flags = flags; 663 th->th_win = htons(tw->last_win); 664 665#ifdef INET6 666 if (isipv6) { 667 if (tw->t_port) { 668 m->m_pkthdr.csum_flags = CSUM_UDP_IPV6; 669 m->m_pkthdr.csum_data = offsetof(struct udphdr, uh_sum); 670 udp->uh_sum = in6_cksum_pseudo(ip6, ulen, IPPROTO_UDP, 0); 671 th->th_sum = htons(0); 672 } else { 673 m->m_pkthdr.csum_flags = CSUM_TCP_IPV6; 674 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 675 th->th_sum = in6_cksum_pseudo(ip6, 676 sizeof(struct tcphdr) + optlen, IPPROTO_TCP, 0); 677 } 678 ip6->ip6_hlim = in6_selecthlim(inp, NULL); 679 TCP_PROBE5(send, NULL, NULL, ip6, NULL, th); 680 error = ip6_output(m, inp->in6p_outputopts, NULL, 681 (tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp); 682 } 683#endif 684#if defined(INET6) && defined(INET) 685 else 686#endif 687#ifdef INET 688 { 689 if (tw->t_port) { 690 m->m_pkthdr.csum_flags = CSUM_UDP; 691 m->m_pkthdr.csum_data = offsetof(struct udphdr, uh_sum); 692 udp->uh_sum = in_pseudo(ip->ip_src.s_addr, 693 ip->ip_dst.s_addr, htons(ulen + IPPROTO_UDP)); 694 th->th_sum = htons(0); 695 } else { 696 m->m_pkthdr.csum_flags = CSUM_TCP; 697 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 698 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 699 htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP)); 700 } 701 ip->ip_len = htons(m->m_pkthdr.len); 702 if (V_path_mtu_discovery) 703 ip->ip_off |= htons(IP_DF); 704 TCP_PROBE5(send, NULL, NULL, ip, NULL, th); 705 error = ip_output(m, inp->inp_options, NULL, 706 ((tw->tw_so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0), 707 NULL, inp); 708 } 709#endif 710 if (flags & TH_ACK) 711 TCPSTAT_INC(tcps_sndacks); 712 else 713 TCPSTAT_INC(tcps_sndctrl); 714 TCPSTAT_INC(tcps_sndtotal); 715 return (error); 716} 717 718static void 719tcp_tw_2msl_reset(struct tcptw *tw, int rearm) 720{ 721 722 NET_EPOCH_ASSERT(); 723 INP_WLOCK_ASSERT(tw->tw_inpcb); 724 725 TW_WLOCK(V_tw_lock); 726 if (rearm) 727 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl); 728 tw->tw_time = ticks + 2 * tcp_msl; 729 TAILQ_INSERT_TAIL(&V_twq_2msl, tw, tw_2msl); 730 TW_WUNLOCK(V_tw_lock); 731} 732 733static void 734tcp_tw_2msl_stop(struct tcptw *tw, int reuse) 735{ 736 struct ucred *cred; 737 struct inpcb *inp; 738 int released __unused; 739 740 NET_EPOCH_ASSERT(); 741 742 TW_WLOCK(V_tw_lock); 743 inp = tw->tw_inpcb; 744 tw->tw_inpcb = NULL; 745 746 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl); 747 cred = tw->tw_cred; 748 tw->tw_cred = NULL; 749 TW_WUNLOCK(V_tw_lock); 750 751 if (cred != NULL) 752 crfree(cred); 753 754 released = in_pcbrele_wlocked(inp); 755 KASSERT(!released, ("%s: inp should not be released here", __func__)); 756 757 if (!reuse) 758 uma_zfree(V_tcptw_zone, tw); 759 TCPSTATES_DEC(TCPS_TIME_WAIT); 760} 761 762struct tcptw * 763tcp_tw_2msl_scan(int reuse) 764{ 765 struct tcptw *tw; 766 struct inpcb *inp; 767 768 NET_EPOCH_ASSERT(); 769 770 for (;;) { 771 TW_RLOCK(V_tw_lock); 772 tw = TAILQ_FIRST(&V_twq_2msl); 773 if (tw == NULL || (!reuse && (tw->tw_time - ticks) > 0)) { 774 TW_RUNLOCK(V_tw_lock); 775 break; 776 } 777 KASSERT(tw->tw_inpcb != NULL, ("%s: tw->tw_inpcb == NULL", 778 __func__)); 779 780 inp = tw->tw_inpcb; 781 in_pcbref(inp); 782 TW_RUNLOCK(V_tw_lock); 783 784 INP_WLOCK(inp); 785 tw = intotw(inp); 786 if (in_pcbrele_wlocked(inp)) { 787 if (__predict_true(tw == NULL)) { 788 continue; 789 } else { 790 /* This should not happen as in TIMEWAIT 791 * state the inp should not be destroyed 792 * before its tcptw. If INVARIANTS is 793 * defined panic. 794 */ 795#ifdef INVARIANTS 796 panic("%s: Panic before an infinite " 797 "loop: INP_TIMEWAIT && (INP_FREED " 798 "|| inp last reference) && tw != " 799 "NULL", __func__); 800#else 801 log(LOG_ERR, "%s: Avoid an infinite " 802 "loop: INP_TIMEWAIT && (INP_FREED " 803 "|| inp last reference) && tw != " 804 "NULL", __func__); 805#endif 806 break; 807 } 808 } 809 810 if (tw == NULL) { 811 /* tcp_twclose() has already been called */ 812 INP_WUNLOCK(inp); 813 continue; 814 } 815 816 tcp_twclose(tw, reuse); 817 if (reuse) 818 return tw; 819 } 820 821 return NULL; 822} 823