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 static VNET_DEFINE(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 static VNET_DEFINE(TAILQ_HEAD(, tcptw), twq_2msl); 115 #define V_twq_2msl VNET(twq_2msl) 116 117 /* Global timewait lock */ 118 static VNET_DEFINE(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(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; 209 210 INP_INFO_RLOCK(&V_tcbinfo); 211 while ((tw = TAILQ_FIRST(&V_twq_2msl)) != NULL) 212 tcp_twclose(tw, 0); 213 INP_INFO_RUNLOCK(&V_tcbinfo); 214 215 TW_LOCK_DESTROY(V_tw_lock); 216 uma_zdestroy(V_tcptw_zone); 217 } 218 #endif 219 220 /* 221 * Move a TCP connection into TIME_WAIT state. 222 * tcbinfo is locked. 223 * inp is locked, and is unlocked before returning. 224 */ 225 void 226 tcp_twstart(struct tcpcb *tp) 227 { 228 struct tcptw *tw; 229 struct inpcb *inp = tp->t_inpcb; 230 int acknow; 231 struct socket *so; 232 #ifdef INET6 233 int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6; 234 #endif 235 236 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 237 INP_WLOCK_ASSERT(inp); 238 239 /* A dropped inp should never transition to TIME_WAIT state. */ 240 KASSERT((inp->inp_flags & INP_DROPPED) == 0, ("tcp_twstart: " 241 "(inp->inp_flags & INP_DROPPED) != 0")); 242 243 if (V_nolocaltimewait) { 244 int error = 0; 245 #ifdef INET6 246 if (isipv6) 247 error = in6_localaddr(&inp->in6p_faddr); 248 #endif 249 #if defined(INET6) && defined(INET) 250 else 251 #endif 252 #ifdef INET 253 error = in_localip(inp->inp_faddr); 254 #endif 255 if (error) { 256 tp = tcp_close(tp); 257 if (tp != NULL) 258 INP_WUNLOCK(inp); 259 return; 260 } 261 } 262 263 264 /* 265 * For use only by DTrace. We do not reference the state 266 * after this point so modifying it in place is not a problem. 267 */ 268 tcp_state_change(tp, TCPS_TIME_WAIT); 269 270 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 * The tcptw will hold a reference on its inpcb until tcp_twclose 290 * is called 291 */ 292 tw->tw_inpcb = inp; 293 in_pcbref(inp); /* Reference from tw */ 294 295 /* 296 * Recover last window size sent. 297 */ 298 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt)) 299 tw->last_win = (tp->rcv_adv - tp->rcv_nxt) >> tp->rcv_scale; 300 else 301 tw->last_win = 0; 302 303 /* 304 * Set t_recent if timestamps are used on the connection. 305 */ 306 if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) == 307 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) { 308 tw->t_recent = tp->ts_recent; 309 tw->ts_offset = tp->ts_offset; 310 } else { 311 tw->t_recent = 0; 312 tw->ts_offset = 0; 313 } 314 315 tw->snd_nxt = tp->snd_nxt; 316 tw->rcv_nxt = tp->rcv_nxt; 317 tw->iss = tp->iss; 318 tw->irs = tp->irs; 319 tw->t_starttime = tp->t_starttime; 320 tw->tw_time = 0; 321 322 /* XXX 323 * If this code will 324 * be used for fin-wait-2 state also, then we may need 325 * a ts_recent from the last segment. 326 */ 327 acknow = tp->t_flags & TF_ACKNOW; 328 329 /* 330 * First, discard tcpcb state, which includes stopping its timers and 331 * freeing it. tcp_discardcb() used to also release the inpcb, but 332 * that work is now done in the caller. 333 * 334 * Note: soisdisconnected() call used to be made in tcp_discardcb(), 335 * and might not be needed here any longer. 336 */ 337 tcp_discardcb(tp); 338 so = inp->inp_socket; 339 soisdisconnected(so); 340 tw->tw_cred = crhold(so->so_cred); 341 SOCK_LOCK(so); 342 tw->tw_so_options = so->so_options; 343 SOCK_UNLOCK(so); 344 if (acknow) 345 tcp_twrespond(tw, TH_ACK); 346 inp->inp_ppcb = tw; 347 inp->inp_flags |= INP_TIMEWAIT; 348 TCPSTATES_INC(TCPS_TIME_WAIT); 349 tcp_tw_2msl_reset(tw, 0); 350 351 /* 352 * If the inpcb owns the sole reference to the socket, then we can 353 * detach and free the socket as it is not needed in time wait. 354 */ 355 if (inp->inp_flags & INP_SOCKREF) { 356 KASSERT(so->so_state & SS_PROTOREF, 357 ("tcp_twstart: !SS_PROTOREF")); 358 inp->inp_flags &= ~INP_SOCKREF; 359 INP_WUNLOCK(inp); 360 SOCK_LOCK(so); 361 so->so_state &= ~SS_PROTOREF; 362 sofree(so); 363 } else 364 INP_WUNLOCK(inp); 365 } 366 367 /* 368 * Returns 1 if the TIME_WAIT state was killed and we should start over, 369 * looking for a pcb in the listen state. Returns 0 otherwise. 370 */ 371 int 372 tcp_twcheck(struct inpcb *inp, struct tcpopt *to __unused, struct tcphdr *th, 373 struct mbuf *m, int tlen) 374 { 375 struct tcptw *tw; 376 int thflags; 377 tcp_seq seq; 378 379 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 380 INP_WLOCK_ASSERT(inp); 381 382 /* 383 * XXXRW: Time wait state for inpcb has been recycled, but inpcb is 384 * still present. This is undesirable, but temporarily necessary 385 * until we work out how to handle inpcb's who's timewait state has 386 * been removed. 387 */ 388 tw = intotw(inp); 389 if (tw == NULL) 390 goto drop; 391 392 thflags = th->th_flags; 393 394 /* 395 * NOTE: for FIN_WAIT_2 (to be added later), 396 * must validate sequence number before accepting RST 397 */ 398 399 /* 400 * If the segment contains RST: 401 * Drop the segment - see Stevens, vol. 2, p. 964 and 402 * RFC 1337. 403 */ 404 if (thflags & TH_RST) 405 goto drop; 406 407 #if 0 408 /* PAWS not needed at the moment */ 409 /* 410 * RFC 1323 PAWS: If we have a timestamp reply on this segment 411 * and it's less than ts_recent, drop it. 412 */ 413 if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent && 414 TSTMP_LT(to.to_tsval, tp->ts_recent)) { 415 if ((thflags & TH_ACK) == 0) 416 goto drop; 417 goto ack; 418 } 419 /* 420 * ts_recent is never updated because we never accept new segments. 421 */ 422 #endif 423 424 /* 425 * If a new connection request is received 426 * while in TIME_WAIT, drop the old connection 427 * and start over if the sequence numbers 428 * are above the previous ones. 429 */ 430 if ((thflags & TH_SYN) && SEQ_GT(th->th_seq, tw->rcv_nxt)) { 431 tcp_twclose(tw, 0); 432 return (1); 433 } 434 435 /* 436 * Drop the segment if it does not contain an ACK. 437 */ 438 if ((thflags & TH_ACK) == 0) 439 goto drop; 440 441 /* 442 * Reset the 2MSL timer if this is a duplicate FIN. 443 */ 444 if (thflags & TH_FIN) { 445 seq = th->th_seq + tlen + (thflags & TH_SYN ? 1 : 0); 446 if (seq + 1 == tw->rcv_nxt) 447 tcp_tw_2msl_reset(tw, 1); 448 } 449 450 /* 451 * Acknowledge the segment if it has data or is not a duplicate ACK. 452 */ 453 if (thflags != TH_ACK || tlen != 0 || 454 th->th_seq != tw->rcv_nxt || th->th_ack != tw->snd_nxt) 455 tcp_twrespond(tw, TH_ACK); 456 drop: 457 INP_WUNLOCK(inp); 458 m_freem(m); 459 return (0); 460 } 461 462 void 463 tcp_twclose(struct tcptw *tw, int reuse) 464 { 465 struct socket *so; 466 struct inpcb *inp; 467 468 /* 469 * At this point, we are in one of two situations: 470 * 471 * (1) We have no socket, just an inpcb<->twtcp pair. We can free 472 * all state. 473 * 474 * (2) We have a socket -- if we own a reference, release it and 475 * notify the socket layer. 476 */ 477 inp = tw->tw_inpcb; 478 KASSERT((inp->inp_flags & INP_TIMEWAIT), ("tcp_twclose: !timewait")); 479 KASSERT(intotw(inp) == tw, ("tcp_twclose: inp_ppcb != tw")); 480 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); /* in_pcbfree() */ 481 INP_WLOCK_ASSERT(inp); 482 483 tcp_tw_2msl_stop(tw, reuse); 484 inp->inp_ppcb = NULL; 485 in_pcbdrop(inp); 486 487 so = inp->inp_socket; 488 if (so != NULL) { 489 /* 490 * If there's a socket, handle two cases: first, we own a 491 * strong reference, which we will now release, or we don't 492 * in which case another reference exists (XXXRW: think 493 * about this more), and we don't need to take action. 494 */ 495 if (inp->inp_flags & INP_SOCKREF) { 496 inp->inp_flags &= ~INP_SOCKREF; 497 INP_WUNLOCK(inp); 498 SOCK_LOCK(so); 499 KASSERT(so->so_state & SS_PROTOREF, 500 ("tcp_twclose: INP_SOCKREF && !SS_PROTOREF")); 501 so->so_state &= ~SS_PROTOREF; 502 sofree(so); 503 } else { 504 /* 505 * If we don't own the only reference, the socket and 506 * inpcb need to be left around to be handled by 507 * tcp_usr_detach() later. 508 */ 509 INP_WUNLOCK(inp); 510 } 511 } else { 512 /* 513 * The socket has been already cleaned-up for us, only free the 514 * inpcb. 515 */ 516 in_pcbfree(inp); 517 } 518 TCPSTAT_INC(tcps_closed); 519 } 520 521 static int 522 tcp_twrespond(struct tcptw *tw, int flags) 523 { 524 struct inpcb *inp = tw->tw_inpcb; 525 #if defined(INET6) || defined(INET) 526 struct tcphdr *th = NULL; 527 #endif 528 struct mbuf *m; 529 #ifdef INET 530 struct ip *ip = NULL; 531 #endif 532 u_int hdrlen, optlen; 533 int error = 0; /* Keep compiler happy */ 534 struct tcpopt to; 535 #ifdef INET6 536 struct ip6_hdr *ip6 = NULL; 537 int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6; 538 #endif 539 hdrlen = 0; /* Keep compiler happy */ 540 541 INP_WLOCK_ASSERT(inp); 542 543 m = m_gethdr(M_NOWAIT, MT_DATA); 544 if (m == NULL) 545 return (ENOBUFS); 546 m->m_data += max_linkhdr; 547 548 #ifdef MAC 549 mac_inpcb_create_mbuf(inp, m); 550 #endif 551 552 #ifdef INET6 553 if (isipv6) { 554 hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 555 ip6 = mtod(m, struct ip6_hdr *); 556 th = (struct tcphdr *)(ip6 + 1); 557 tcpip_fillheaders(inp, ip6, th); 558 } 559 #endif 560 #if defined(INET6) && defined(INET) 561 else 562 #endif 563 #ifdef INET 564 { 565 hdrlen = sizeof(struct tcpiphdr); 566 ip = mtod(m, struct ip *); 567 th = (struct tcphdr *)(ip + 1); 568 tcpip_fillheaders(inp, ip, th); 569 } 570 #endif 571 to.to_flags = 0; 572 573 /* 574 * Send a timestamp and echo-reply if both our side and our peer 575 * have sent timestamps in our SYN's and this is not a RST. 576 */ 577 if (tw->t_recent && flags == TH_ACK) { 578 to.to_flags |= TOF_TS; 579 to.to_tsval = tcp_ts_getticks() + tw->ts_offset; 580 to.to_tsecr = tw->t_recent; 581 } 582 optlen = tcp_addoptions(&to, (u_char *)(th + 1)); 583 584 m->m_len = hdrlen + optlen; 585 m->m_pkthdr.len = m->m_len; 586 587 KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small")); 588 589 th->th_seq = htonl(tw->snd_nxt); 590 th->th_ack = htonl(tw->rcv_nxt); 591 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 592 th->th_flags = flags; 593 th->th_win = htons(tw->last_win); 594 595 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 596 #ifdef INET6 597 if (isipv6) { 598 m->m_pkthdr.csum_flags = CSUM_TCP_IPV6; 599 th->th_sum = in6_cksum_pseudo(ip6, 600 sizeof(struct tcphdr) + optlen, IPPROTO_TCP, 0); 601 ip6->ip6_hlim = in6_selecthlim(inp, NULL); 602 error = ip6_output(m, inp->in6p_outputopts, NULL, 603 (tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp); 604 } 605 #endif 606 #if defined(INET6) && defined(INET) 607 else 608 #endif 609 #ifdef INET 610 { 611 m->m_pkthdr.csum_flags = CSUM_TCP; 612 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 613 htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP)); 614 ip->ip_len = htons(m->m_pkthdr.len); 615 if (V_path_mtu_discovery) 616 ip->ip_off |= htons(IP_DF); 617 error = ip_output(m, inp->inp_options, NULL, 618 ((tw->tw_so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0), 619 NULL, inp); 620 } 621 #endif 622 if (flags & TH_ACK) 623 TCPSTAT_INC(tcps_sndacks); 624 else 625 TCPSTAT_INC(tcps_sndctrl); 626 TCPSTAT_INC(tcps_sndtotal); 627 return (error); 628 } 629 630 static void 631 tcp_tw_2msl_reset(struct tcptw *tw, int rearm) 632 { 633 634 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 635 INP_WLOCK_ASSERT(tw->tw_inpcb); 636 637 TW_WLOCK(V_tw_lock); 638 if (rearm) 639 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl); 640 tw->tw_time = ticks + 2 * tcp_msl; 641 TAILQ_INSERT_TAIL(&V_twq_2msl, tw, tw_2msl); 642 TW_WUNLOCK(V_tw_lock); 643 } 644 645 static void 646 tcp_tw_2msl_stop(struct tcptw *tw, int reuse) 647 { 648 struct ucred *cred; 649 struct inpcb *inp; 650 int released; 651 652 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 653 654 TW_WLOCK(V_tw_lock); 655 inp = tw->tw_inpcb; 656 tw->tw_inpcb = NULL; 657 658 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl); 659 cred = tw->tw_cred; 660 tw->tw_cred = NULL; 661 TW_WUNLOCK(V_tw_lock); 662 663 if (cred != NULL) 664 crfree(cred); 665 666 released = in_pcbrele_wlocked(inp); 667 KASSERT(!released, ("%s: inp should not be released here", __func__)); 668 669 if (!reuse) 670 uma_zfree(V_tcptw_zone, tw); 671 TCPSTATES_DEC(TCPS_TIME_WAIT); 672 } 673 674 struct tcptw * 675 tcp_tw_2msl_scan(int reuse) 676 { 677 struct tcptw *tw; 678 struct inpcb *inp; 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 if (INP_INFO_TRY_RLOCK(&V_tcbinfo)) { 713 714 INP_WLOCK(inp); 715 tw = intotw(inp); 716 if (in_pcbrele_wlocked(inp)) { 717 if (__predict_true(tw == NULL)) { 718 INP_INFO_RUNLOCK(&V_tcbinfo); 719 continue; 720 } else { 721 /* This should not happen as in TIMEWAIT 722 * state the inp should not be destroyed 723 * before its tcptw. If INVARIANTS is 724 * defined panic. 725 */ 726 #ifdef INVARIANTS 727 panic("%s: Panic before an infinite " 728 "loop: INP_TIMEWAIT && (INP_FREED " 729 "|| inp last reference) && tw != " 730 "NULL", __func__); 731 #else 732 log(LOG_ERR, "%s: Avoid an infinite " 733 "loop: INP_TIMEWAIT && (INP_FREED " 734 "|| inp last reference) && tw != " 735 "NULL", __func__); 736 #endif 737 INP_INFO_RUNLOCK(&V_tcbinfo); 738 break; 739 } 740 } 741 742 if (tw == NULL) { 743 /* tcp_twclose() has already been called */ 744 INP_WUNLOCK(inp); 745 INP_INFO_RUNLOCK(&V_tcbinfo); 746 continue; 747 } 748 749 tcp_twclose(tw, reuse); 750 INP_INFO_RUNLOCK(&V_tcbinfo); 751 if (reuse) 752 return tw; 753 } else { 754 /* INP_INFO lock is busy, continue later. */ 755 INP_WLOCK(inp); 756 if (!in_pcbrele_wlocked(inp)) 757 INP_WUNLOCK(inp); 758 break; 759 } 760 } 761 762 return NULL; 763 } 764