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_pcb.h> 67 #include <netinet/in_systm.h> 68 #include <netinet/in_var.h> 69 #include <netinet/ip.h> 70 #include <netinet/ip_icmp.h> 71 #include <netinet/ip_var.h> 72 #ifdef INET6 73 #include <netinet/ip6.h> 74 #include <netinet6/in6_pcb.h> 75 #include <netinet6/ip6_var.h> 76 #include <netinet6/scope6_var.h> 77 #include <netinet6/nd6.h> 78 #endif 79 #include <netinet/tcp.h> 80 #include <netinet/tcp_fsm.h> 81 #include <netinet/tcp_seq.h> 82 #include <netinet/tcp_timer.h> 83 #include <netinet/tcp_var.h> 84 #ifdef INET6 85 #include <netinet6/tcp6_var.h> 86 #endif 87 #include <netinet/tcpip.h> 88 #ifdef TCPDEBUG 89 #include <netinet/tcp_debug.h> 90 #endif 91 #ifdef INET6 92 #include <netinet6/ip6protosw.h> 93 #endif 94 95 #include <machine/in_cksum.h> 96 97 #include <security/mac/mac_framework.h> 98 99 VNET_DEFINE_STATIC(uma_zone_t, tcptw_zone); 100 #define V_tcptw_zone VNET(tcptw_zone) 101 static int maxtcptw; 102 103 /* 104 * The timed wait queue contains references to each of the TCP sessions 105 * currently in the TIME_WAIT state. The queue pointers, including the 106 * queue pointers in each tcptw structure, are protected using the global 107 * timewait lock, which must be held over queue iteration and modification. 108 * 109 * Rules on tcptw usage: 110 * - a inpcb is always freed _after_ its tcptw 111 * - a tcptw relies on its inpcb reference counting for memory stability 112 * - a tcptw is dereferenceable only while its inpcb is locked 113 */ 114 VNET_DEFINE_STATIC(TAILQ_HEAD(, tcptw), twq_2msl); 115 #define V_twq_2msl VNET(twq_2msl) 116 117 /* Global timewait lock */ 118 VNET_DEFINE_STATIC(struct rwlock, tw_lock); 119 #define V_tw_lock VNET(tw_lock) 120 121 #define TW_LOCK_INIT(tw, d) rw_init_flags(&(tw), (d), 0) 122 #define TW_LOCK_DESTROY(tw) rw_destroy(&(tw)) 123 #define TW_RLOCK(tw) rw_rlock(&(tw)) 124 #define TW_WLOCK(tw) rw_wlock(&(tw)) 125 #define TW_RUNLOCK(tw) rw_runlock(&(tw)) 126 #define TW_WUNLOCK(tw) rw_wunlock(&(tw)) 127 #define TW_LOCK_ASSERT(tw) rw_assert(&(tw), RA_LOCKED) 128 #define TW_RLOCK_ASSERT(tw) rw_assert(&(tw), RA_RLOCKED) 129 #define TW_WLOCK_ASSERT(tw) rw_assert(&(tw), RA_WLOCKED) 130 #define TW_UNLOCK_ASSERT(tw) rw_assert(&(tw), RA_UNLOCKED) 131 132 static void tcp_tw_2msl_reset(struct tcptw *, int); 133 static void tcp_tw_2msl_stop(struct tcptw *, int); 134 static int tcp_twrespond(struct tcptw *, int); 135 136 static int 137 tcptw_auto_size(void) 138 { 139 int halfrange; 140 141 /* 142 * Max out at half the ephemeral port range so that TIME_WAIT 143 * sockets don't tie up too many ephemeral ports. 144 */ 145 if (V_ipport_lastauto > V_ipport_firstauto) 146 halfrange = (V_ipport_lastauto - V_ipport_firstauto) / 2; 147 else 148 halfrange = (V_ipport_firstauto - V_ipport_lastauto) / 2; 149 /* Protect against goofy port ranges smaller than 32. */ 150 return (imin(imax(halfrange, 32), maxsockets / 5)); 151 } 152 153 static int 154 sysctl_maxtcptw(SYSCTL_HANDLER_ARGS) 155 { 156 int error, new; 157 158 if (maxtcptw == 0) 159 new = tcptw_auto_size(); 160 else 161 new = maxtcptw; 162 error = sysctl_handle_int(oidp, &new, 0, req); 163 if (error == 0 && req->newptr) 164 if (new >= 32) { 165 maxtcptw = new; 166 uma_zone_set_max(V_tcptw_zone, maxtcptw); 167 } 168 return (error); 169 } 170 171 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, maxtcptw, CTLTYPE_INT|CTLFLAG_RW, 172 &maxtcptw, 0, sysctl_maxtcptw, "IU", 173 "Maximum number of compressed TCP TIME_WAIT entries"); 174 175 VNET_DEFINE_STATIC(int, nolocaltimewait) = 0; 176 #define V_nolocaltimewait VNET(nolocaltimewait) 177 SYSCTL_INT(_net_inet_tcp, OID_AUTO, nolocaltimewait, CTLFLAG_VNET | CTLFLAG_RW, 178 &VNET_NAME(nolocaltimewait), 0, 179 "Do not create compressed TCP TIME_WAIT entries for local connections"); 180 181 void 182 tcp_tw_zone_change(void) 183 { 184 185 if (maxtcptw == 0) 186 uma_zone_set_max(V_tcptw_zone, tcptw_auto_size()); 187 } 188 189 void 190 tcp_tw_init(void) 191 { 192 193 V_tcptw_zone = uma_zcreate("tcptw", sizeof(struct tcptw), 194 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 195 TUNABLE_INT_FETCH("net.inet.tcp.maxtcptw", &maxtcptw); 196 if (maxtcptw == 0) 197 uma_zone_set_max(V_tcptw_zone, tcptw_auto_size()); 198 else 199 uma_zone_set_max(V_tcptw_zone, maxtcptw); 200 TAILQ_INIT(&V_twq_2msl); 201 TW_LOCK_INIT(V_tw_lock, "tcptw"); 202 } 203 204 #ifdef VIMAGE 205 void 206 tcp_tw_destroy(void) 207 { 208 struct tcptw *tw; 209 struct epoch_tracker et; 210 211 INP_INFO_RLOCK_ET(&V_tcbinfo, et); 212 while ((tw = TAILQ_FIRST(&V_twq_2msl)) != NULL) 213 tcp_twclose(tw, 0); 214 INP_INFO_RUNLOCK_ET(&V_tcbinfo, et); 215 216 TW_LOCK_DESTROY(V_tw_lock); 217 uma_zdestroy(V_tcptw_zone); 218 } 219 #endif 220 221 /* 222 * Move a TCP connection into TIME_WAIT state. 223 * tcbinfo is locked. 224 * inp is locked, and is unlocked before returning. 225 */ 226 void 227 tcp_twstart(struct tcpcb *tp) 228 { 229 struct tcptw twlocal, *tw; 230 struct inpcb *inp = tp->t_inpcb; 231 struct socket *so; 232 bool acknow, local; 233 #ifdef INET6 234 bool isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6; 235 #endif 236 237 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 238 INP_WLOCK_ASSERT(inp); 239 240 /* A dropped inp should never transition to TIME_WAIT state. */ 241 KASSERT((inp->inp_flags & INP_DROPPED) == 0, ("tcp_twstart: " 242 "(inp->inp_flags & INP_DROPPED) != 0")); 243 244 if (V_nolocaltimewait) { 245 #ifdef INET6 246 if (isipv6) 247 local = in6_localaddr(&inp->in6p_faddr); 248 else 249 #endif 250 #ifdef INET 251 local = in_localip(inp->inp_faddr); 252 #else 253 local = false; 254 #endif 255 } else 256 local = false; 257 258 /* 259 * For use only by DTrace. We do not reference the state 260 * after this point so modifying it in place is not a problem. 261 */ 262 tcp_state_change(tp, TCPS_TIME_WAIT); 263 264 if (local) 265 tw = &twlocal; 266 else 267 tw = uma_zalloc(V_tcptw_zone, M_NOWAIT); 268 if (tw == NULL) { 269 /* 270 * Reached limit on total number of TIMEWAIT connections 271 * allowed. Remove a connection from TIMEWAIT queue in LRU 272 * fashion to make room for this connection. 273 * 274 * XXX: Check if it possible to always have enough room 275 * in advance based on guarantees provided by uma_zalloc(). 276 */ 277 tw = tcp_tw_2msl_scan(1); 278 if (tw == NULL) { 279 tp = tcp_close(tp); 280 if (tp != NULL) 281 INP_WUNLOCK(inp); 282 return; 283 } 284 } 285 /* 286 * For !local case the tcptw will hold a reference on its inpcb 287 * until tcp_twclose is called. 288 */ 289 tw->tw_inpcb = inp; 290 291 /* 292 * Recover last window size sent. 293 */ 294 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt)) 295 tw->last_win = (tp->rcv_adv - tp->rcv_nxt) >> tp->rcv_scale; 296 else 297 tw->last_win = 0; 298 299 /* 300 * Set t_recent if timestamps are used on the connection. 301 */ 302 if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) == 303 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) { 304 tw->t_recent = tp->ts_recent; 305 tw->ts_offset = tp->ts_offset; 306 } else { 307 tw->t_recent = 0; 308 tw->ts_offset = 0; 309 } 310 311 tw->snd_nxt = tp->snd_nxt; 312 tw->rcv_nxt = tp->rcv_nxt; 313 tw->iss = tp->iss; 314 tw->irs = tp->irs; 315 tw->t_starttime = tp->t_starttime; 316 tw->tw_time = 0; 317 318 /* XXX 319 * If this code will 320 * be used for fin-wait-2 state also, then we may need 321 * a ts_recent from the last segment. 322 */ 323 acknow = tp->t_flags & TF_ACKNOW; 324 325 /* 326 * First, discard tcpcb state, which includes stopping its timers and 327 * freeing it. tcp_discardcb() used to also release the inpcb, but 328 * that work is now done in the caller. 329 * 330 * Note: soisdisconnected() call used to be made in tcp_discardcb(), 331 * and might not be needed here any longer. 332 */ 333 tcp_discardcb(tp); 334 so = inp->inp_socket; 335 soisdisconnected(so); 336 tw->tw_so_options = so->so_options; 337 inp->inp_flags |= INP_TIMEWAIT; 338 if (acknow) 339 tcp_twrespond(tw, TH_ACK); 340 if (local) 341 in_pcbdrop(inp); 342 else { 343 in_pcbref(inp); /* Reference from tw */ 344 tw->tw_cred = crhold(so->so_cred); 345 inp->inp_ppcb = tw; 346 TCPSTATES_INC(TCPS_TIME_WAIT); 347 tcp_tw_2msl_reset(tw, 0); 348 } 349 350 /* 351 * If the inpcb owns the sole reference to the socket, then we can 352 * detach and free the socket as it is not needed in time wait. 353 */ 354 if (inp->inp_flags & INP_SOCKREF) { 355 KASSERT(so->so_state & SS_PROTOREF, 356 ("tcp_twstart: !SS_PROTOREF")); 357 inp->inp_flags &= ~INP_SOCKREF; 358 INP_WUNLOCK(inp); 359 SOCK_LOCK(so); 360 so->so_state &= ~SS_PROTOREF; 361 sofree(so); 362 } else 363 INP_WUNLOCK(inp); 364 } 365 366 /* 367 * Returns 1 if the TIME_WAIT state was killed and we should start over, 368 * looking for a pcb in the listen state. Returns 0 otherwise. 369 */ 370 int 371 tcp_twcheck(struct inpcb *inp, struct tcpopt *to __unused, struct tcphdr *th, 372 struct mbuf *m, int tlen) 373 { 374 struct tcptw *tw; 375 int thflags; 376 tcp_seq seq; 377 378 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 379 INP_WLOCK_ASSERT(inp); 380 381 /* 382 * XXXRW: Time wait state for inpcb has been recycled, but inpcb is 383 * still present. This is undesirable, but temporarily necessary 384 * until we work out how to handle inpcb's who's timewait state has 385 * been removed. 386 */ 387 tw = intotw(inp); 388 if (tw == NULL) 389 goto drop; 390 391 thflags = th->th_flags; 392 393 /* 394 * NOTE: for FIN_WAIT_2 (to be added later), 395 * must validate sequence number before accepting RST 396 */ 397 398 /* 399 * If the segment contains RST: 400 * Drop the segment - see Stevens, vol. 2, p. 964 and 401 * RFC 1337. 402 */ 403 if (thflags & TH_RST) 404 goto drop; 405 406 #if 0 407 /* PAWS not needed at the moment */ 408 /* 409 * RFC 1323 PAWS: If we have a timestamp reply on this segment 410 * and it's less than ts_recent, drop it. 411 */ 412 if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent && 413 TSTMP_LT(to.to_tsval, tp->ts_recent)) { 414 if ((thflags & TH_ACK) == 0) 415 goto drop; 416 goto ack; 417 } 418 /* 419 * ts_recent is never updated because we never accept new segments. 420 */ 421 #endif 422 423 /* 424 * If a new connection request is received 425 * while in TIME_WAIT, drop the old connection 426 * and start over if the sequence numbers 427 * are above the previous ones. 428 */ 429 if ((thflags & TH_SYN) && SEQ_GT(th->th_seq, tw->rcv_nxt)) { 430 tcp_twclose(tw, 0); 431 return (1); 432 } 433 434 /* 435 * Drop the segment if it does not contain an ACK. 436 */ 437 if ((thflags & TH_ACK) == 0) 438 goto drop; 439 440 /* 441 * Reset the 2MSL timer if this is a duplicate FIN. 442 */ 443 if (thflags & TH_FIN) { 444 seq = th->th_seq + tlen + (thflags & TH_SYN ? 1 : 0); 445 if (seq + 1 == tw->rcv_nxt) 446 tcp_tw_2msl_reset(tw, 1); 447 } 448 449 /* 450 * Acknowledge the segment if it has data or is not a duplicate ACK. 451 */ 452 if (thflags != TH_ACK || tlen != 0 || 453 th->th_seq != tw->rcv_nxt || th->th_ack != tw->snd_nxt) 454 tcp_twrespond(tw, TH_ACK); 455 drop: 456 INP_WUNLOCK(inp); 457 m_freem(m); 458 return (0); 459 } 460 461 void 462 tcp_twclose(struct tcptw *tw, int reuse) 463 { 464 struct socket *so; 465 struct inpcb *inp; 466 467 /* 468 * At this point, we are in one of two situations: 469 * 470 * (1) We have no socket, just an inpcb<->twtcp pair. We can free 471 * all state. 472 * 473 * (2) We have a socket -- if we own a reference, release it and 474 * notify the socket layer. 475 */ 476 inp = tw->tw_inpcb; 477 KASSERT((inp->inp_flags & INP_TIMEWAIT), ("tcp_twclose: !timewait")); 478 KASSERT(intotw(inp) == tw, ("tcp_twclose: inp_ppcb != tw")); 479 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); /* in_pcbfree() */ 480 INP_WLOCK_ASSERT(inp); 481 482 tcp_tw_2msl_stop(tw, reuse); 483 inp->inp_ppcb = NULL; 484 in_pcbdrop(inp); 485 486 so = inp->inp_socket; 487 if (so != NULL) { 488 /* 489 * If there's a socket, handle two cases: first, we own a 490 * strong reference, which we will now release, or we don't 491 * in which case another reference exists (XXXRW: think 492 * about this more), and we don't need to take action. 493 */ 494 if (inp->inp_flags & INP_SOCKREF) { 495 inp->inp_flags &= ~INP_SOCKREF; 496 INP_WUNLOCK(inp); 497 SOCK_LOCK(so); 498 KASSERT(so->so_state & SS_PROTOREF, 499 ("tcp_twclose: INP_SOCKREF && !SS_PROTOREF")); 500 so->so_state &= ~SS_PROTOREF; 501 sofree(so); 502 } else { 503 /* 504 * If we don't own the only reference, the socket and 505 * inpcb need to be left around to be handled by 506 * tcp_usr_detach() later. 507 */ 508 INP_WUNLOCK(inp); 509 } 510 } else { 511 /* 512 * The socket has been already cleaned-up for us, only free the 513 * inpcb. 514 */ 515 in_pcbfree(inp); 516 } 517 TCPSTAT_INC(tcps_closed); 518 } 519 520 static int 521 tcp_twrespond(struct tcptw *tw, int flags) 522 { 523 struct inpcb *inp = tw->tw_inpcb; 524 #if defined(INET6) || defined(INET) 525 struct tcphdr *th = NULL; 526 #endif 527 struct mbuf *m; 528 #ifdef INET 529 struct ip *ip = NULL; 530 #endif 531 u_int hdrlen, optlen; 532 int error = 0; /* Keep compiler happy */ 533 struct tcpopt to; 534 #ifdef INET6 535 struct ip6_hdr *ip6 = NULL; 536 int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6; 537 #endif 538 hdrlen = 0; /* Keep compiler happy */ 539 540 INP_WLOCK_ASSERT(inp); 541 542 m = m_gethdr(M_NOWAIT, MT_DATA); 543 if (m == NULL) 544 return (ENOBUFS); 545 m->m_data += max_linkhdr; 546 547 #ifdef MAC 548 mac_inpcb_create_mbuf(inp, m); 549 #endif 550 551 #ifdef INET6 552 if (isipv6) { 553 hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 554 ip6 = mtod(m, struct ip6_hdr *); 555 th = (struct tcphdr *)(ip6 + 1); 556 tcpip_fillheaders(inp, ip6, th); 557 } 558 #endif 559 #if defined(INET6) && defined(INET) 560 else 561 #endif 562 #ifdef INET 563 { 564 hdrlen = sizeof(struct tcpiphdr); 565 ip = mtod(m, struct ip *); 566 th = (struct tcphdr *)(ip + 1); 567 tcpip_fillheaders(inp, ip, th); 568 } 569 #endif 570 to.to_flags = 0; 571 572 /* 573 * Send a timestamp and echo-reply if both our side and our peer 574 * have sent timestamps in our SYN's and this is not a RST. 575 */ 576 if (tw->t_recent && flags == TH_ACK) { 577 to.to_flags |= TOF_TS; 578 to.to_tsval = tcp_ts_getticks() + tw->ts_offset; 579 to.to_tsecr = tw->t_recent; 580 } 581 optlen = tcp_addoptions(&to, (u_char *)(th + 1)); 582 583 m->m_len = hdrlen + optlen; 584 m->m_pkthdr.len = m->m_len; 585 586 KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small")); 587 588 th->th_seq = htonl(tw->snd_nxt); 589 th->th_ack = htonl(tw->rcv_nxt); 590 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 591 th->th_flags = flags; 592 th->th_win = htons(tw->last_win); 593 594 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 595 #ifdef INET6 596 if (isipv6) { 597 m->m_pkthdr.csum_flags = CSUM_TCP_IPV6; 598 th->th_sum = in6_cksum_pseudo(ip6, 599 sizeof(struct tcphdr) + optlen, IPPROTO_TCP, 0); 600 ip6->ip6_hlim = in6_selecthlim(inp, NULL); 601 error = ip6_output(m, inp->in6p_outputopts, NULL, 602 (tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp); 603 } 604 #endif 605 #if defined(INET6) && defined(INET) 606 else 607 #endif 608 #ifdef INET 609 { 610 m->m_pkthdr.csum_flags = CSUM_TCP; 611 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 612 htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP)); 613 ip->ip_len = htons(m->m_pkthdr.len); 614 if (V_path_mtu_discovery) 615 ip->ip_off |= htons(IP_DF); 616 error = ip_output(m, inp->inp_options, NULL, 617 ((tw->tw_so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0), 618 NULL, inp); 619 } 620 #endif 621 if (flags & TH_ACK) 622 TCPSTAT_INC(tcps_sndacks); 623 else 624 TCPSTAT_INC(tcps_sndctrl); 625 TCPSTAT_INC(tcps_sndtotal); 626 return (error); 627 } 628 629 static void 630 tcp_tw_2msl_reset(struct tcptw *tw, int rearm) 631 { 632 633 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 634 INP_WLOCK_ASSERT(tw->tw_inpcb); 635 636 TW_WLOCK(V_tw_lock); 637 if (rearm) 638 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl); 639 tw->tw_time = ticks + 2 * tcp_msl; 640 TAILQ_INSERT_TAIL(&V_twq_2msl, tw, tw_2msl); 641 TW_WUNLOCK(V_tw_lock); 642 } 643 644 static void 645 tcp_tw_2msl_stop(struct tcptw *tw, int reuse) 646 { 647 struct ucred *cred; 648 struct inpcb *inp; 649 int released __unused; 650 651 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 652 653 TW_WLOCK(V_tw_lock); 654 inp = tw->tw_inpcb; 655 tw->tw_inpcb = NULL; 656 657 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl); 658 cred = tw->tw_cred; 659 tw->tw_cred = NULL; 660 TW_WUNLOCK(V_tw_lock); 661 662 if (cred != NULL) 663 crfree(cred); 664 665 released = in_pcbrele_wlocked(inp); 666 KASSERT(!released, ("%s: inp should not be released here", __func__)); 667 668 if (!reuse) 669 uma_zfree(V_tcptw_zone, tw); 670 TCPSTATES_DEC(TCPS_TIME_WAIT); 671 } 672 673 struct tcptw * 674 tcp_tw_2msl_scan(int reuse) 675 { 676 struct tcptw *tw; 677 struct inpcb *inp; 678 struct epoch_tracker et; 679 680 #ifdef INVARIANTS 681 if (reuse) { 682 /* 683 * Exclusive pcbinfo lock is not required in reuse case even if 684 * two inpcb locks can be acquired simultaneously: 685 * - the inpcb transitioning to TIME_WAIT state in 686 * tcp_tw_start(), 687 * - the inpcb closed by tcp_twclose(). 688 * 689 * It is because only inpcbs in FIN_WAIT2 or CLOSING states can 690 * transition in TIME_WAIT state. Then a pcbcb cannot be in 691 * TIME_WAIT list and transitioning to TIME_WAIT state at same 692 * time. 693 */ 694 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 695 } 696 #endif 697 698 for (;;) { 699 TW_RLOCK(V_tw_lock); 700 tw = TAILQ_FIRST(&V_twq_2msl); 701 if (tw == NULL || (!reuse && (tw->tw_time - ticks) > 0)) { 702 TW_RUNLOCK(V_tw_lock); 703 break; 704 } 705 KASSERT(tw->tw_inpcb != NULL, ("%s: tw->tw_inpcb == NULL", 706 __func__)); 707 708 inp = tw->tw_inpcb; 709 in_pcbref(inp); 710 TW_RUNLOCK(V_tw_lock); 711 712 INP_INFO_RLOCK_ET(&V_tcbinfo, et); 713 INP_WLOCK(inp); 714 tw = intotw(inp); 715 if (in_pcbrele_wlocked(inp)) { 716 if (__predict_true(tw == NULL)) { 717 INP_INFO_RUNLOCK_ET(&V_tcbinfo, et); 718 continue; 719 } else { 720 /* This should not happen as in TIMEWAIT 721 * state the inp should not be destroyed 722 * before its tcptw. If INVARIANTS is 723 * defined panic. 724 */ 725 #ifdef INVARIANTS 726 panic("%s: Panic before an infinite " 727 "loop: INP_TIMEWAIT && (INP_FREED " 728 "|| inp last reference) && tw != " 729 "NULL", __func__); 730 #else 731 log(LOG_ERR, "%s: Avoid an infinite " 732 "loop: INP_TIMEWAIT && (INP_FREED " 733 "|| inp last reference) && tw != " 734 "NULL", __func__); 735 #endif 736 INP_INFO_RUNLOCK_ET(&V_tcbinfo, et); 737 break; 738 } 739 } 740 741 if (tw == NULL) { 742 /* tcp_twclose() has already been called */ 743 INP_WUNLOCK(inp); 744 INP_INFO_RUNLOCK_ET(&V_tcbinfo, et); 745 continue; 746 } 747 748 tcp_twclose(tw, reuse); 749 INP_INFO_RUNLOCK_ET(&V_tcbinfo, et); 750 if (reuse) 751 return tw; 752 } 753 754 return NULL; 755 } 756