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 <machine/in_cksum.h> 97 98 #include <security/mac/mac_framework.h> 99 100 VNET_DEFINE_STATIC(uma_zone_t, tcptw_zone); 101 #define V_tcptw_zone VNET(tcptw_zone) 102 static int maxtcptw; 103 104 /* 105 * The timed wait queue contains references to each of the TCP sessions 106 * currently in the TIME_WAIT state. The queue pointers, including the 107 * queue pointers in each tcptw structure, are protected using the global 108 * timewait lock, which must be held over queue iteration and modification. 109 * 110 * Rules on tcptw usage: 111 * - a inpcb is always freed _after_ its tcptw 112 * - a tcptw relies on its inpcb reference counting for memory stability 113 * - a tcptw is dereferenceable only while its inpcb is locked 114 */ 115 VNET_DEFINE_STATIC(TAILQ_HEAD(, tcptw), twq_2msl); 116 #define V_twq_2msl VNET(twq_2msl) 117 118 /* Global timewait lock */ 119 VNET_DEFINE_STATIC(struct rwlock, tw_lock); 120 #define V_tw_lock VNET(tw_lock) 121 122 #define TW_LOCK_INIT(tw, d) rw_init_flags(&(tw), (d), 0) 123 #define TW_LOCK_DESTROY(tw) rw_destroy(&(tw)) 124 #define TW_RLOCK(tw) rw_rlock(&(tw)) 125 #define TW_WLOCK(tw) rw_wlock(&(tw)) 126 #define TW_RUNLOCK(tw) rw_runlock(&(tw)) 127 #define TW_WUNLOCK(tw) rw_wunlock(&(tw)) 128 #define TW_LOCK_ASSERT(tw) rw_assert(&(tw), RA_LOCKED) 129 #define TW_RLOCK_ASSERT(tw) rw_assert(&(tw), RA_RLOCKED) 130 #define TW_WLOCK_ASSERT(tw) rw_assert(&(tw), RA_WLOCKED) 131 #define TW_UNLOCK_ASSERT(tw) rw_assert(&(tw), RA_UNLOCKED) 132 133 static void tcp_tw_2msl_reset(struct tcptw *, int); 134 static void tcp_tw_2msl_stop(struct tcptw *, int); 135 static int tcp_twrespond(struct tcptw *, int); 136 137 static int 138 tcptw_auto_size(void) 139 { 140 int halfrange; 141 142 /* 143 * Max out at half the ephemeral port range so that TIME_WAIT 144 * sockets don't tie up too many ephemeral ports. 145 */ 146 if (V_ipport_lastauto > V_ipport_firstauto) 147 halfrange = (V_ipport_lastauto - V_ipport_firstauto) / 2; 148 else 149 halfrange = (V_ipport_firstauto - V_ipport_lastauto) / 2; 150 /* Protect against goofy port ranges smaller than 32. */ 151 return (imin(imax(halfrange, 32), maxsockets / 5)); 152 } 153 154 static int 155 sysctl_maxtcptw(SYSCTL_HANDLER_ARGS) 156 { 157 int error, new; 158 159 if (maxtcptw == 0) 160 new = tcptw_auto_size(); 161 else 162 new = maxtcptw; 163 error = sysctl_handle_int(oidp, &new, 0, req); 164 if (error == 0 && req->newptr) 165 if (new >= 32) { 166 maxtcptw = new; 167 uma_zone_set_max(V_tcptw_zone, maxtcptw); 168 } 169 return (error); 170 } 171 172 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, maxtcptw, 173 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 174 &maxtcptw, 0, sysctl_maxtcptw, "IU", 175 "Maximum number of compressed TCP TIME_WAIT entries"); 176 177 VNET_DEFINE_STATIC(int, nolocaltimewait) = 0; 178 #define V_nolocaltimewait VNET(nolocaltimewait) 179 SYSCTL_INT(_net_inet_tcp, OID_AUTO, nolocaltimewait, CTLFLAG_VNET | CTLFLAG_RW, 180 &VNET_NAME(nolocaltimewait), 0, 181 "Do not create compressed TCP TIME_WAIT entries for local connections"); 182 183 void 184 tcp_tw_zone_change(void) 185 { 186 187 if (maxtcptw == 0) 188 uma_zone_set_max(V_tcptw_zone, tcptw_auto_size()); 189 } 190 191 void 192 tcp_tw_init(void) 193 { 194 195 V_tcptw_zone = uma_zcreate("tcptw", sizeof(struct tcptw), 196 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 197 TUNABLE_INT_FETCH("net.inet.tcp.maxtcptw", &maxtcptw); 198 if (maxtcptw == 0) 199 uma_zone_set_max(V_tcptw_zone, tcptw_auto_size()); 200 else 201 uma_zone_set_max(V_tcptw_zone, maxtcptw); 202 TAILQ_INIT(&V_twq_2msl); 203 TW_LOCK_INIT(V_tw_lock, "tcptw"); 204 } 205 206 #ifdef VIMAGE 207 void 208 tcp_tw_destroy(void) 209 { 210 struct tcptw *tw; 211 struct epoch_tracker et; 212 213 NET_EPOCH_ENTER(et); 214 while ((tw = TAILQ_FIRST(&V_twq_2msl)) != NULL) 215 tcp_twclose(tw, 0); 216 NET_EPOCH_EXIT(et); 217 218 TW_LOCK_DESTROY(V_tw_lock); 219 uma_zdestroy(V_tcptw_zone); 220 } 221 #endif 222 223 /* 224 * Move a TCP connection into TIME_WAIT state. 225 * tcbinfo is locked. 226 * inp is locked, and is unlocked before returning. 227 */ 228 void 229 tcp_twstart(struct tcpcb *tp) 230 { 231 struct tcptw twlocal, *tw; 232 struct inpcb *inp = tp->t_inpcb; 233 struct socket *so; 234 uint32_t recwin; 235 bool acknow, local; 236 #ifdef INET6 237 bool isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6; 238 #endif 239 240 NET_EPOCH_ASSERT(); 241 INP_WLOCK_ASSERT(inp); 242 243 /* A dropped inp should never transition to TIME_WAIT state. */ 244 KASSERT((inp->inp_flags & INP_DROPPED) == 0, ("tcp_twstart: " 245 "(inp->inp_flags & INP_DROPPED) != 0")); 246 247 if (V_nolocaltimewait) { 248 #ifdef INET6 249 if (isipv6) 250 local = in6_localaddr(&inp->in6p_faddr); 251 else 252 #endif 253 #ifdef INET 254 local = in_localip(inp->inp_faddr); 255 #else 256 local = false; 257 #endif 258 } else 259 local = false; 260 261 /* 262 * For use only by DTrace. We do not reference the state 263 * after this point so modifying it in place is not a problem. 264 */ 265 tcp_state_change(tp, TCPS_TIME_WAIT); 266 267 if (local) 268 tw = &twlocal; 269 else 270 tw = uma_zalloc(V_tcptw_zone, M_NOWAIT); 271 if (tw == NULL) { 272 /* 273 * Reached limit on total number of TIMEWAIT connections 274 * allowed. Remove a connection from TIMEWAIT queue in LRU 275 * fashion to make room for this connection. 276 * 277 * XXX: Check if it possible to always have enough room 278 * in advance based on guarantees provided by uma_zalloc(). 279 */ 280 tw = tcp_tw_2msl_scan(1); 281 if (tw == NULL) { 282 tp = tcp_close(tp); 283 if (tp != NULL) 284 INP_WUNLOCK(inp); 285 return; 286 } 287 } 288 /* 289 * For !local case the tcptw will hold a reference on its inpcb 290 * until tcp_twclose is called. 291 */ 292 tw->tw_inpcb = inp; 293 294 /* 295 * Recover last window size sent. 296 */ 297 so = inp->inp_socket; 298 recwin = lmin(lmax(sbspace(&so->so_rcv), 0), 299 (long)TCP_MAXWIN << tp->rcv_scale); 300 if (recwin < (so->so_rcv.sb_hiwat / 4) && 301 recwin < tp->t_maxseg) 302 recwin = 0; 303 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt) && 304 recwin < (tp->rcv_adv - tp->rcv_nxt)) 305 recwin = (tp->rcv_adv - tp->rcv_nxt); 306 tw->last_win = (u_short)(recwin >> tp->rcv_scale); 307 308 /* 309 * Set t_recent if timestamps are used on the connection. 310 */ 311 if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) == 312 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) { 313 tw->t_recent = tp->ts_recent; 314 tw->ts_offset = tp->ts_offset; 315 } else { 316 tw->t_recent = 0; 317 tw->ts_offset = 0; 318 } 319 320 tw->snd_nxt = tp->snd_nxt; 321 tw->rcv_nxt = tp->rcv_nxt; 322 tw->iss = tp->iss; 323 tw->irs = tp->irs; 324 tw->t_starttime = tp->t_starttime; 325 tw->tw_time = 0; 326 327 /* XXX 328 * If this code will 329 * be used for fin-wait-2 state also, then we may need 330 * a ts_recent from the last segment. 331 */ 332 acknow = tp->t_flags & TF_ACKNOW; 333 334 /* 335 * First, discard tcpcb state, which includes stopping its timers and 336 * freeing it. tcp_discardcb() used to also release the inpcb, but 337 * that work is now done in the caller. 338 * 339 * Note: soisdisconnected() call used to be made in tcp_discardcb(), 340 * and might not be needed here any longer. 341 */ 342 tcp_discardcb(tp); 343 soisdisconnected(so); 344 tw->tw_so_options = so->so_options; 345 inp->inp_flags |= INP_TIMEWAIT; 346 if (acknow) 347 tcp_twrespond(tw, TH_ACK); 348 if (local) 349 in_pcbdrop(inp); 350 else { 351 in_pcbref(inp); /* Reference from tw */ 352 tw->tw_cred = crhold(so->so_cred); 353 inp->inp_ppcb = tw; 354 TCPSTATES_INC(TCPS_TIME_WAIT); 355 tcp_tw_2msl_reset(tw, 0); 356 } 357 358 /* 359 * If the inpcb owns the sole reference to the socket, then we can 360 * detach and free the socket as it is not needed in time wait. 361 */ 362 if (inp->inp_flags & INP_SOCKREF) { 363 KASSERT(so->so_state & SS_PROTOREF, 364 ("tcp_twstart: !SS_PROTOREF")); 365 inp->inp_flags &= ~INP_SOCKREF; 366 INP_WUNLOCK(inp); 367 SOCK_LOCK(so); 368 so->so_state &= ~SS_PROTOREF; 369 sofree(so); 370 } else 371 INP_WUNLOCK(inp); 372 } 373 374 /* 375 * Returns 1 if the TIME_WAIT state was killed and we should start over, 376 * looking for a pcb in the listen state. Returns 0 otherwise. 377 * It be called with to == NULL only for pure SYN-segments. 378 */ 379 int 380 tcp_twcheck(struct inpcb *inp, struct tcpopt *to, struct tcphdr *th, 381 struct mbuf *m, int tlen) 382 { 383 struct tcptw *tw; 384 int thflags; 385 tcp_seq seq; 386 387 NET_EPOCH_ASSERT(); 388 INP_WLOCK_ASSERT(inp); 389 390 /* 391 * XXXRW: Time wait state for inpcb has been recycled, but inpcb is 392 * still present. This is undesirable, but temporarily necessary 393 * until we work out how to handle inpcb's who's timewait state has 394 * been removed. 395 */ 396 tw = intotw(inp); 397 if (tw == NULL) 398 goto drop; 399 400 thflags = th->th_flags; 401 KASSERT(to != NULL || (thflags & (TH_SYN | TH_ACK)) == TH_SYN, 402 ("tcp_twcheck: called without options on a non-SYN segment")); 403 404 /* 405 * NOTE: for FIN_WAIT_2 (to be added later), 406 * must validate sequence number before accepting RST 407 */ 408 409 /* 410 * If the segment contains RST: 411 * Drop the segment - see Stevens, vol. 2, p. 964 and 412 * RFC 1337. 413 */ 414 if (thflags & TH_RST) 415 goto drop; 416 417 #if 0 418 /* PAWS not needed at the moment */ 419 /* 420 * RFC 1323 PAWS: If we have a timestamp reply on this segment 421 * and it's less than ts_recent, drop it. 422 */ 423 if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent && 424 TSTMP_LT(to.to_tsval, tp->ts_recent)) { 425 if ((thflags & TH_ACK) == 0) 426 goto drop; 427 goto ack; 428 } 429 /* 430 * ts_recent is never updated because we never accept new segments. 431 */ 432 #endif 433 434 /* 435 * If a new connection request is received 436 * while in TIME_WAIT, drop the old connection 437 * and start over if the sequence numbers 438 * are above the previous ones. 439 */ 440 if ((thflags & TH_SYN) && SEQ_GT(th->th_seq, tw->rcv_nxt)) { 441 tcp_twclose(tw, 0); 442 return (1); 443 } 444 445 /* 446 * Drop the segment if it does not contain an ACK. 447 */ 448 if ((thflags & TH_ACK) == 0) 449 goto drop; 450 451 /* 452 * If timestamps were negotiated during SYN/ACK and a 453 * segment without a timestamp is received, silently drop 454 * the segment. 455 * See section 3.2 of RFC 7323. 456 */ 457 if (((to->to_flags & TOF_TS) == 0) && (tw->t_recent != 0)) { 458 goto drop; 459 } 460 461 /* 462 * Reset the 2MSL timer if this is a duplicate FIN. 463 */ 464 if (thflags & TH_FIN) { 465 seq = th->th_seq + tlen + (thflags & TH_SYN ? 1 : 0); 466 if (seq + 1 == tw->rcv_nxt) 467 tcp_tw_2msl_reset(tw, 1); 468 } 469 470 /* 471 * Acknowledge the segment if it has data or is not a duplicate ACK. 472 */ 473 if (thflags != TH_ACK || tlen != 0 || 474 th->th_seq != tw->rcv_nxt || th->th_ack != tw->snd_nxt) { 475 TCP_PROBE5(receive, NULL, NULL, m, NULL, th); 476 tcp_twrespond(tw, TH_ACK); 477 goto dropnoprobe; 478 } 479 drop: 480 TCP_PROBE5(receive, NULL, NULL, m, NULL, th); 481 dropnoprobe: 482 INP_WUNLOCK(inp); 483 m_freem(m); 484 return (0); 485 } 486 487 void 488 tcp_twclose(struct tcptw *tw, int reuse) 489 { 490 struct socket *so; 491 struct inpcb *inp; 492 493 /* 494 * At this point, we are in one of two situations: 495 * 496 * (1) We have no socket, just an inpcb<->twtcp pair. We can free 497 * all state. 498 * 499 * (2) We have a socket -- if we own a reference, release it and 500 * notify the socket layer. 501 */ 502 inp = tw->tw_inpcb; 503 KASSERT((inp->inp_flags & INP_TIMEWAIT), ("tcp_twclose: !timewait")); 504 KASSERT(intotw(inp) == tw, ("tcp_twclose: inp_ppcb != tw")); 505 NET_EPOCH_ASSERT(); 506 INP_WLOCK_ASSERT(inp); 507 508 tcp_tw_2msl_stop(tw, reuse); 509 inp->inp_ppcb = NULL; 510 in_pcbdrop(inp); 511 512 so = inp->inp_socket; 513 if (so != NULL) { 514 /* 515 * If there's a socket, handle two cases: first, we own a 516 * strong reference, which we will now release, or we don't 517 * in which case another reference exists (XXXRW: think 518 * about this more), and we don't need to take action. 519 */ 520 if (inp->inp_flags & INP_SOCKREF) { 521 inp->inp_flags &= ~INP_SOCKREF; 522 INP_WUNLOCK(inp); 523 SOCK_LOCK(so); 524 KASSERT(so->so_state & SS_PROTOREF, 525 ("tcp_twclose: INP_SOCKREF && !SS_PROTOREF")); 526 so->so_state &= ~SS_PROTOREF; 527 sofree(so); 528 } else { 529 /* 530 * If we don't own the only reference, the socket and 531 * inpcb need to be left around to be handled by 532 * tcp_usr_detach() later. 533 */ 534 INP_WUNLOCK(inp); 535 } 536 } else { 537 /* 538 * The socket has been already cleaned-up for us, only free the 539 * inpcb. 540 */ 541 in_pcbfree(inp); 542 } 543 TCPSTAT_INC(tcps_closed); 544 } 545 546 static int 547 tcp_twrespond(struct tcptw *tw, int flags) 548 { 549 struct inpcb *inp = tw->tw_inpcb; 550 #if defined(INET6) || defined(INET) 551 struct tcphdr *th = NULL; 552 #endif 553 struct mbuf *m; 554 #ifdef INET 555 struct ip *ip = NULL; 556 #endif 557 u_int hdrlen, optlen; 558 int error = 0; /* Keep compiler happy */ 559 struct tcpopt to; 560 #ifdef INET6 561 struct ip6_hdr *ip6 = NULL; 562 int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6; 563 #endif 564 hdrlen = 0; /* Keep compiler happy */ 565 566 INP_WLOCK_ASSERT(inp); 567 568 m = m_gethdr(M_NOWAIT, MT_DATA); 569 if (m == NULL) 570 return (ENOBUFS); 571 m->m_data += max_linkhdr; 572 573 #ifdef MAC 574 mac_inpcb_create_mbuf(inp, m); 575 #endif 576 577 #ifdef INET6 578 if (isipv6) { 579 hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 580 ip6 = mtod(m, struct ip6_hdr *); 581 th = (struct tcphdr *)(ip6 + 1); 582 tcpip_fillheaders(inp, ip6, th); 583 } 584 #endif 585 #if defined(INET6) && defined(INET) 586 else 587 #endif 588 #ifdef INET 589 { 590 hdrlen = sizeof(struct tcpiphdr); 591 ip = mtod(m, struct ip *); 592 th = (struct tcphdr *)(ip + 1); 593 tcpip_fillheaders(inp, ip, th); 594 } 595 #endif 596 to.to_flags = 0; 597 598 /* 599 * Send a timestamp and echo-reply if both our side and our peer 600 * have sent timestamps in our SYN's and this is not a RST. 601 */ 602 if (tw->t_recent && flags == TH_ACK) { 603 to.to_flags |= TOF_TS; 604 to.to_tsval = tcp_ts_getticks() + tw->ts_offset; 605 to.to_tsecr = tw->t_recent; 606 } 607 optlen = tcp_addoptions(&to, (u_char *)(th + 1)); 608 609 m->m_len = hdrlen + optlen; 610 m->m_pkthdr.len = m->m_len; 611 612 KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small")); 613 614 th->th_seq = htonl(tw->snd_nxt); 615 th->th_ack = htonl(tw->rcv_nxt); 616 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 617 th->th_flags = flags; 618 th->th_win = htons(tw->last_win); 619 620 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 621 #ifdef INET6 622 if (isipv6) { 623 m->m_pkthdr.csum_flags = CSUM_TCP_IPV6; 624 th->th_sum = in6_cksum_pseudo(ip6, 625 sizeof(struct tcphdr) + optlen, IPPROTO_TCP, 0); 626 ip6->ip6_hlim = in6_selecthlim(inp, NULL); 627 TCP_PROBE5(send, NULL, NULL, ip6, NULL, th); 628 error = ip6_output(m, inp->in6p_outputopts, NULL, 629 (tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp); 630 } 631 #endif 632 #if defined(INET6) && defined(INET) 633 else 634 #endif 635 #ifdef INET 636 { 637 m->m_pkthdr.csum_flags = CSUM_TCP; 638 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 639 htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP)); 640 ip->ip_len = htons(m->m_pkthdr.len); 641 if (V_path_mtu_discovery) 642 ip->ip_off |= htons(IP_DF); 643 TCP_PROBE5(send, NULL, NULL, ip, NULL, th); 644 error = ip_output(m, inp->inp_options, NULL, 645 ((tw->tw_so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0), 646 NULL, inp); 647 } 648 #endif 649 if (flags & TH_ACK) 650 TCPSTAT_INC(tcps_sndacks); 651 else 652 TCPSTAT_INC(tcps_sndctrl); 653 TCPSTAT_INC(tcps_sndtotal); 654 return (error); 655 } 656 657 static void 658 tcp_tw_2msl_reset(struct tcptw *tw, int rearm) 659 { 660 661 NET_EPOCH_ASSERT(); 662 INP_WLOCK_ASSERT(tw->tw_inpcb); 663 664 TW_WLOCK(V_tw_lock); 665 if (rearm) 666 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl); 667 tw->tw_time = ticks + 2 * tcp_msl; 668 TAILQ_INSERT_TAIL(&V_twq_2msl, tw, tw_2msl); 669 TW_WUNLOCK(V_tw_lock); 670 } 671 672 static void 673 tcp_tw_2msl_stop(struct tcptw *tw, int reuse) 674 { 675 struct ucred *cred; 676 struct inpcb *inp; 677 int released __unused; 678 679 NET_EPOCH_ASSERT(); 680 681 TW_WLOCK(V_tw_lock); 682 inp = tw->tw_inpcb; 683 tw->tw_inpcb = NULL; 684 685 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl); 686 cred = tw->tw_cred; 687 tw->tw_cred = NULL; 688 TW_WUNLOCK(V_tw_lock); 689 690 if (cred != NULL) 691 crfree(cred); 692 693 released = in_pcbrele_wlocked(inp); 694 KASSERT(!released, ("%s: inp should not be released here", __func__)); 695 696 if (!reuse) 697 uma_zfree(V_tcptw_zone, tw); 698 TCPSTATES_DEC(TCPS_TIME_WAIT); 699 } 700 701 struct tcptw * 702 tcp_tw_2msl_scan(int reuse) 703 { 704 struct tcptw *tw; 705 struct inpcb *inp; 706 707 NET_EPOCH_ASSERT(); 708 709 for (;;) { 710 TW_RLOCK(V_tw_lock); 711 tw = TAILQ_FIRST(&V_twq_2msl); 712 if (tw == NULL || (!reuse && (tw->tw_time - ticks) > 0)) { 713 TW_RUNLOCK(V_tw_lock); 714 break; 715 } 716 KASSERT(tw->tw_inpcb != NULL, ("%s: tw->tw_inpcb == NULL", 717 __func__)); 718 719 inp = tw->tw_inpcb; 720 in_pcbref(inp); 721 TW_RUNLOCK(V_tw_lock); 722 723 INP_WLOCK(inp); 724 tw = intotw(inp); 725 if (in_pcbrele_wlocked(inp)) { 726 if (__predict_true(tw == NULL)) { 727 continue; 728 } else { 729 /* This should not happen as in TIMEWAIT 730 * state the inp should not be destroyed 731 * before its tcptw. If INVARIANTS is 732 * defined panic. 733 */ 734 #ifdef INVARIANTS 735 panic("%s: Panic before an infinite " 736 "loop: INP_TIMEWAIT && (INP_FREED " 737 "|| inp last reference) && tw != " 738 "NULL", __func__); 739 #else 740 log(LOG_ERR, "%s: Avoid an infinite " 741 "loop: INP_TIMEWAIT && (INP_FREED " 742 "|| inp last reference) && tw != " 743 "NULL", __func__); 744 #endif 745 break; 746 } 747 } 748 749 if (tw == NULL) { 750 /* tcp_twclose() has already been called */ 751 INP_WUNLOCK(inp); 752 continue; 753 } 754 755 tcp_twclose(tw, reuse); 756 if (reuse) 757 return tw; 758 } 759 760 return NULL; 761 } 762