1 /*- 2 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * @(#)tcp_subr.c 8.2 (Berkeley) 5/24/95 30 */ 31 32 #include <sys/cdefs.h> 33 __FBSDID("$FreeBSD$"); 34 35 #include "opt_inet.h" 36 #include "opt_inet6.h" 37 #include "opt_tcpdebug.h" 38 39 #include <sys/param.h> 40 #include <sys/systm.h> 41 #include <sys/callout.h> 42 #include <sys/kernel.h> 43 #include <sys/sysctl.h> 44 #include <sys/malloc.h> 45 #include <sys/mbuf.h> 46 #include <sys/priv.h> 47 #include <sys/proc.h> 48 #include <sys/socket.h> 49 #include <sys/socketvar.h> 50 #include <sys/protosw.h> 51 #include <sys/random.h> 52 53 #include <vm/uma.h> 54 55 #include <net/route.h> 56 #include <net/if.h> 57 #include <net/if_var.h> 58 #include <net/vnet.h> 59 60 #include <netinet/in.h> 61 #include <netinet/in_pcb.h> 62 #include <netinet/in_systm.h> 63 #include <netinet/in_var.h> 64 #include <netinet/ip.h> 65 #include <netinet/ip_icmp.h> 66 #include <netinet/ip_var.h> 67 #ifdef INET6 68 #include <netinet/ip6.h> 69 #include <netinet6/in6_pcb.h> 70 #include <netinet6/ip6_var.h> 71 #include <netinet6/scope6_var.h> 72 #include <netinet6/nd6.h> 73 #endif 74 #include <netinet/tcp.h> 75 #include <netinet/tcp_fsm.h> 76 #include <netinet/tcp_seq.h> 77 #include <netinet/tcp_timer.h> 78 #include <netinet/tcp_var.h> 79 #ifdef INET6 80 #include <netinet6/tcp6_var.h> 81 #endif 82 #include <netinet/tcpip.h> 83 #ifdef TCPDEBUG 84 #include <netinet/tcp_debug.h> 85 #endif 86 #ifdef INET6 87 #include <netinet6/ip6protosw.h> 88 #endif 89 90 #include <machine/in_cksum.h> 91 92 #include <security/mac/mac_framework.h> 93 94 static VNET_DEFINE(uma_zone_t, tcptw_zone); 95 #define V_tcptw_zone VNET(tcptw_zone) 96 static int maxtcptw; 97 98 /* 99 * The timed wait queue contains references to each of the TCP sessions 100 * currently in the TIME_WAIT state. The queue pointers, including the 101 * queue pointers in each tcptw structure, are protected using the global 102 * timewait lock, which must be held over queue iteration and modification. 103 * 104 * Rules on tcptw usage: 105 * - a inpcb is always freed _after_ its tcptw 106 * - a tcptw relies on its inpcb reference counting for memory stability 107 * - a tcptw is dereferenceable only while its inpcb is locked 108 */ 109 static VNET_DEFINE(TAILQ_HEAD(, tcptw), twq_2msl); 110 #define V_twq_2msl VNET(twq_2msl) 111 112 /* Global timewait lock */ 113 static VNET_DEFINE(struct rwlock, tw_lock); 114 #define V_tw_lock VNET(tw_lock) 115 116 #define TW_LOCK_INIT(tw, d) rw_init_flags(&(tw), (d), 0) 117 #define TW_LOCK_DESTROY(tw) rw_destroy(&(tw)) 118 #define TW_RLOCK(tw) rw_rlock(&(tw)) 119 #define TW_WLOCK(tw) rw_wlock(&(tw)) 120 #define TW_RUNLOCK(tw) rw_runlock(&(tw)) 121 #define TW_WUNLOCK(tw) rw_wunlock(&(tw)) 122 #define TW_LOCK_ASSERT(tw) rw_assert(&(tw), RA_LOCKED) 123 #define TW_RLOCK_ASSERT(tw) rw_assert(&(tw), RA_RLOCKED) 124 #define TW_WLOCK_ASSERT(tw) rw_assert(&(tw), RA_WLOCKED) 125 #define TW_UNLOCK_ASSERT(tw) rw_assert(&(tw), RA_UNLOCKED) 126 127 static void tcp_tw_2msl_reset(struct tcptw *, int); 128 static void tcp_tw_2msl_stop(struct tcptw *, int); 129 static int tcp_twrespond(struct tcptw *, int); 130 131 static int 132 tcptw_auto_size(void) 133 { 134 int halfrange; 135 136 /* 137 * Max out at half the ephemeral port range so that TIME_WAIT 138 * sockets don't tie up too many ephemeral ports. 139 */ 140 if (V_ipport_lastauto > V_ipport_firstauto) 141 halfrange = (V_ipport_lastauto - V_ipport_firstauto) / 2; 142 else 143 halfrange = (V_ipport_firstauto - V_ipport_lastauto) / 2; 144 /* Protect against goofy port ranges smaller than 32. */ 145 return (imin(imax(halfrange, 32), maxsockets / 5)); 146 } 147 148 static int 149 sysctl_maxtcptw(SYSCTL_HANDLER_ARGS) 150 { 151 int error, new; 152 153 if (maxtcptw == 0) 154 new = tcptw_auto_size(); 155 else 156 new = maxtcptw; 157 error = sysctl_handle_int(oidp, &new, 0, req); 158 if (error == 0 && req->newptr) 159 if (new >= 32) { 160 maxtcptw = new; 161 uma_zone_set_max(V_tcptw_zone, maxtcptw); 162 } 163 return (error); 164 } 165 166 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, maxtcptw, CTLTYPE_INT|CTLFLAG_RW, 167 &maxtcptw, 0, sysctl_maxtcptw, "IU", 168 "Maximum number of compressed TCP TIME_WAIT entries"); 169 170 VNET_DEFINE(int, nolocaltimewait) = 0; 171 #define V_nolocaltimewait VNET(nolocaltimewait) 172 SYSCTL_INT(_net_inet_tcp, OID_AUTO, nolocaltimewait, CTLFLAG_VNET | CTLFLAG_RW, 173 &VNET_NAME(nolocaltimewait), 0, 174 "Do not create compressed TCP TIME_WAIT entries for local connections"); 175 176 void 177 tcp_tw_zone_change(void) 178 { 179 180 if (maxtcptw == 0) 181 uma_zone_set_max(V_tcptw_zone, tcptw_auto_size()); 182 } 183 184 void 185 tcp_tw_init(void) 186 { 187 188 V_tcptw_zone = uma_zcreate("tcptw", sizeof(struct tcptw), 189 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 190 TUNABLE_INT_FETCH("net.inet.tcp.maxtcptw", &maxtcptw); 191 if (maxtcptw == 0) 192 uma_zone_set_max(V_tcptw_zone, tcptw_auto_size()); 193 else 194 uma_zone_set_max(V_tcptw_zone, maxtcptw); 195 TAILQ_INIT(&V_twq_2msl); 196 TW_LOCK_INIT(V_tw_lock, "tcptw"); 197 } 198 199 #ifdef VIMAGE 200 void 201 tcp_tw_destroy(void) 202 { 203 struct tcptw *tw; 204 205 INP_INFO_RLOCK(&V_tcbinfo); 206 while ((tw = TAILQ_FIRST(&V_twq_2msl)) != NULL) 207 tcp_twclose(tw, 0); 208 INP_INFO_RUNLOCK(&V_tcbinfo); 209 210 TW_LOCK_DESTROY(V_tw_lock); 211 uma_zdestroy(V_tcptw_zone); 212 } 213 #endif 214 215 /* 216 * Move a TCP connection into TIME_WAIT state. 217 * tcbinfo is locked. 218 * inp is locked, and is unlocked before returning. 219 */ 220 void 221 tcp_twstart(struct tcpcb *tp) 222 { 223 struct tcptw *tw; 224 struct inpcb *inp = tp->t_inpcb; 225 int acknow; 226 struct socket *so; 227 #ifdef INET6 228 int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6; 229 #endif 230 231 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 232 INP_WLOCK_ASSERT(inp); 233 234 /* A dropped inp should never transition to TIME_WAIT state. */ 235 KASSERT((inp->inp_flags & INP_DROPPED) == 0, ("tcp_twstart: " 236 "(inp->inp_flags & INP_DROPPED) != 0")); 237 238 if (V_nolocaltimewait) { 239 int error = 0; 240 #ifdef INET6 241 if (isipv6) 242 error = in6_localaddr(&inp->in6p_faddr); 243 #endif 244 #if defined(INET6) && defined(INET) 245 else 246 #endif 247 #ifdef INET 248 error = in_localip(inp->inp_faddr); 249 #endif 250 if (error) { 251 tp = tcp_close(tp); 252 if (tp != NULL) 253 INP_WUNLOCK(inp); 254 return; 255 } 256 } 257 258 259 /* 260 * For use only by DTrace. We do not reference the state 261 * after this point so modifying it in place is not a problem. 262 */ 263 tcp_state_change(tp, TCPS_TIME_WAIT); 264 265 tw = uma_zalloc(V_tcptw_zone, M_NOWAIT); 266 if (tw == NULL) { 267 /* 268 * Reached limit on total number of TIMEWAIT connections 269 * allowed. Remove a connection from TIMEWAIT queue in LRU 270 * fashion to make room for this connection. 271 * 272 * XXX: Check if it possible to always have enough room 273 * in advance based on guarantees provided by uma_zalloc(). 274 */ 275 tw = tcp_tw_2msl_scan(1); 276 if (tw == NULL) { 277 tp = tcp_close(tp); 278 if (tp != NULL) 279 INP_WUNLOCK(inp); 280 return; 281 } 282 } 283 /* 284 * The tcptw will hold a reference on its inpcb until tcp_twclose 285 * is called 286 */ 287 tw->tw_inpcb = inp; 288 in_pcbref(inp); /* Reference from tw */ 289 290 /* 291 * Recover last window size sent. 292 */ 293 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt)) 294 tw->last_win = (tp->rcv_adv - tp->rcv_nxt) >> tp->rcv_scale; 295 else 296 tw->last_win = 0; 297 298 /* 299 * Set t_recent if timestamps are used on the connection. 300 */ 301 if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) == 302 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) { 303 tw->t_recent = tp->ts_recent; 304 tw->ts_offset = tp->ts_offset; 305 } else { 306 tw->t_recent = 0; 307 tw->ts_offset = 0; 308 } 309 310 tw->snd_nxt = tp->snd_nxt; 311 tw->rcv_nxt = tp->rcv_nxt; 312 tw->iss = tp->iss; 313 tw->irs = tp->irs; 314 tw->t_starttime = tp->t_starttime; 315 tw->tw_time = 0; 316 317 /* XXX 318 * If this code will 319 * be used for fin-wait-2 state also, then we may need 320 * a ts_recent from the last segment. 321 */ 322 acknow = tp->t_flags & TF_ACKNOW; 323 324 /* 325 * First, discard tcpcb state, which includes stopping its timers and 326 * freeing it. tcp_discardcb() used to also release the inpcb, but 327 * that work is now done in the caller. 328 * 329 * Note: soisdisconnected() call used to be made in tcp_discardcb(), 330 * and might not be needed here any longer. 331 */ 332 tcp_discardcb(tp); 333 so = inp->inp_socket; 334 soisdisconnected(so); 335 tw->tw_cred = crhold(so->so_cred); 336 SOCK_LOCK(so); 337 tw->tw_so_options = so->so_options; 338 SOCK_UNLOCK(so); 339 if (acknow) 340 tcp_twrespond(tw, TH_ACK); 341 inp->inp_ppcb = tw; 342 inp->inp_flags |= INP_TIMEWAIT; 343 TCPSTATES_INC(TCPS_TIME_WAIT); 344 tcp_tw_2msl_reset(tw, 0); 345 346 /* 347 * If the inpcb owns the sole reference to the socket, then we can 348 * detach and free the socket as it is not needed in time wait. 349 */ 350 if (inp->inp_flags & INP_SOCKREF) { 351 KASSERT(so->so_state & SS_PROTOREF, 352 ("tcp_twstart: !SS_PROTOREF")); 353 inp->inp_flags &= ~INP_SOCKREF; 354 INP_WUNLOCK(inp); 355 SOCK_LOCK(so); 356 so->so_state &= ~SS_PROTOREF; 357 sofree(so); 358 } else 359 INP_WUNLOCK(inp); 360 } 361 362 /* 363 * Returns 1 if the TIME_WAIT state was killed and we should start over, 364 * looking for a pcb in the listen state. Returns 0 otherwise. 365 */ 366 int 367 tcp_twcheck(struct inpcb *inp, struct tcpopt *to __unused, struct tcphdr *th, 368 struct mbuf *m, int tlen) 369 { 370 struct tcptw *tw; 371 int thflags; 372 tcp_seq seq; 373 374 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 375 INP_WLOCK_ASSERT(inp); 376 377 /* 378 * XXXRW: Time wait state for inpcb has been recycled, but inpcb is 379 * still present. This is undesirable, but temporarily necessary 380 * until we work out how to handle inpcb's who's timewait state has 381 * been removed. 382 */ 383 tw = intotw(inp); 384 if (tw == NULL) 385 goto drop; 386 387 thflags = th->th_flags; 388 389 /* 390 * NOTE: for FIN_WAIT_2 (to be added later), 391 * must validate sequence number before accepting RST 392 */ 393 394 /* 395 * If the segment contains RST: 396 * Drop the segment - see Stevens, vol. 2, p. 964 and 397 * RFC 1337. 398 */ 399 if (thflags & TH_RST) 400 goto drop; 401 402 #if 0 403 /* PAWS not needed at the moment */ 404 /* 405 * RFC 1323 PAWS: If we have a timestamp reply on this segment 406 * and it's less than ts_recent, drop it. 407 */ 408 if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent && 409 TSTMP_LT(to.to_tsval, tp->ts_recent)) { 410 if ((thflags & TH_ACK) == 0) 411 goto drop; 412 goto ack; 413 } 414 /* 415 * ts_recent is never updated because we never accept new segments. 416 */ 417 #endif 418 419 /* 420 * If a new connection request is received 421 * while in TIME_WAIT, drop the old connection 422 * and start over if the sequence numbers 423 * are above the previous ones. 424 */ 425 if ((thflags & TH_SYN) && SEQ_GT(th->th_seq, tw->rcv_nxt)) { 426 tcp_twclose(tw, 0); 427 return (1); 428 } 429 430 /* 431 * Drop the segment if it does not contain an ACK. 432 */ 433 if ((thflags & TH_ACK) == 0) 434 goto drop; 435 436 /* 437 * Reset the 2MSL timer if this is a duplicate FIN. 438 */ 439 if (thflags & TH_FIN) { 440 seq = th->th_seq + tlen + (thflags & TH_SYN ? 1 : 0); 441 if (seq + 1 == tw->rcv_nxt) 442 tcp_tw_2msl_reset(tw, 1); 443 } 444 445 /* 446 * Acknowledge the segment if it has data or is not a duplicate ACK. 447 */ 448 if (thflags != TH_ACK || tlen != 0 || 449 th->th_seq != tw->rcv_nxt || th->th_ack != tw->snd_nxt) 450 tcp_twrespond(tw, TH_ACK); 451 drop: 452 INP_WUNLOCK(inp); 453 m_freem(m); 454 return (0); 455 } 456 457 void 458 tcp_twclose(struct tcptw *tw, int reuse) 459 { 460 struct socket *so; 461 struct inpcb *inp; 462 463 /* 464 * At this point, we are in one of two situations: 465 * 466 * (1) We have no socket, just an inpcb<->twtcp pair. We can free 467 * all state. 468 * 469 * (2) We have a socket -- if we own a reference, release it and 470 * notify the socket layer. 471 */ 472 inp = tw->tw_inpcb; 473 KASSERT((inp->inp_flags & INP_TIMEWAIT), ("tcp_twclose: !timewait")); 474 KASSERT(intotw(inp) == tw, ("tcp_twclose: inp_ppcb != tw")); 475 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); /* in_pcbfree() */ 476 INP_WLOCK_ASSERT(inp); 477 478 tcp_tw_2msl_stop(tw, reuse); 479 inp->inp_ppcb = NULL; 480 in_pcbdrop(inp); 481 482 so = inp->inp_socket; 483 if (so != NULL) { 484 /* 485 * If there's a socket, handle two cases: first, we own a 486 * strong reference, which we will now release, or we don't 487 * in which case another reference exists (XXXRW: think 488 * about this more), and we don't need to take action. 489 */ 490 if (inp->inp_flags & INP_SOCKREF) { 491 inp->inp_flags &= ~INP_SOCKREF; 492 INP_WUNLOCK(inp); 493 SOCK_LOCK(so); 494 KASSERT(so->so_state & SS_PROTOREF, 495 ("tcp_twclose: INP_SOCKREF && !SS_PROTOREF")); 496 so->so_state &= ~SS_PROTOREF; 497 sofree(so); 498 } else { 499 /* 500 * If we don't own the only reference, the socket and 501 * inpcb need to be left around to be handled by 502 * tcp_usr_detach() later. 503 */ 504 INP_WUNLOCK(inp); 505 } 506 } else { 507 /* 508 * The socket has been already cleaned-up for us, only free the 509 * inpcb. 510 */ 511 in_pcbfree(inp); 512 } 513 TCPSTAT_INC(tcps_closed); 514 } 515 516 static int 517 tcp_twrespond(struct tcptw *tw, int flags) 518 { 519 struct inpcb *inp = tw->tw_inpcb; 520 #if defined(INET6) || defined(INET) 521 struct tcphdr *th = NULL; 522 #endif 523 struct mbuf *m; 524 #ifdef INET 525 struct ip *ip = NULL; 526 #endif 527 u_int hdrlen, optlen; 528 int error = 0; /* Keep compiler happy */ 529 struct tcpopt to; 530 #ifdef INET6 531 struct ip6_hdr *ip6 = NULL; 532 int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6; 533 #endif 534 hdrlen = 0; /* Keep compiler happy */ 535 536 INP_WLOCK_ASSERT(inp); 537 538 m = m_gethdr(M_NOWAIT, MT_DATA); 539 if (m == NULL) 540 return (ENOBUFS); 541 m->m_data += max_linkhdr; 542 543 #ifdef MAC 544 mac_inpcb_create_mbuf(inp, m); 545 #endif 546 547 #ifdef INET6 548 if (isipv6) { 549 hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 550 ip6 = mtod(m, struct ip6_hdr *); 551 th = (struct tcphdr *)(ip6 + 1); 552 tcpip_fillheaders(inp, ip6, th); 553 } 554 #endif 555 #if defined(INET6) && defined(INET) 556 else 557 #endif 558 #ifdef INET 559 { 560 hdrlen = sizeof(struct tcpiphdr); 561 ip = mtod(m, struct ip *); 562 th = (struct tcphdr *)(ip + 1); 563 tcpip_fillheaders(inp, ip, th); 564 } 565 #endif 566 to.to_flags = 0; 567 568 /* 569 * Send a timestamp and echo-reply if both our side and our peer 570 * have sent timestamps in our SYN's and this is not a RST. 571 */ 572 if (tw->t_recent && flags == TH_ACK) { 573 to.to_flags |= TOF_TS; 574 to.to_tsval = tcp_ts_getticks() + tw->ts_offset; 575 to.to_tsecr = tw->t_recent; 576 } 577 optlen = tcp_addoptions(&to, (u_char *)(th + 1)); 578 579 m->m_len = hdrlen + optlen; 580 m->m_pkthdr.len = m->m_len; 581 582 KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small")); 583 584 th->th_seq = htonl(tw->snd_nxt); 585 th->th_ack = htonl(tw->rcv_nxt); 586 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 587 th->th_flags = flags; 588 th->th_win = htons(tw->last_win); 589 590 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 591 #ifdef INET6 592 if (isipv6) { 593 m->m_pkthdr.csum_flags = CSUM_TCP_IPV6; 594 th->th_sum = in6_cksum_pseudo(ip6, 595 sizeof(struct tcphdr) + optlen, IPPROTO_TCP, 0); 596 ip6->ip6_hlim = in6_selecthlim(inp, NULL); 597 error = ip6_output(m, inp->in6p_outputopts, NULL, 598 (tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp); 599 } 600 #endif 601 #if defined(INET6) && defined(INET) 602 else 603 #endif 604 #ifdef INET 605 { 606 m->m_pkthdr.csum_flags = CSUM_TCP; 607 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 608 htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP)); 609 ip->ip_len = htons(m->m_pkthdr.len); 610 if (V_path_mtu_discovery) 611 ip->ip_off |= htons(IP_DF); 612 error = ip_output(m, inp->inp_options, NULL, 613 ((tw->tw_so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0), 614 NULL, inp); 615 } 616 #endif 617 if (flags & TH_ACK) 618 TCPSTAT_INC(tcps_sndacks); 619 else 620 TCPSTAT_INC(tcps_sndctrl); 621 TCPSTAT_INC(tcps_sndtotal); 622 return (error); 623 } 624 625 static void 626 tcp_tw_2msl_reset(struct tcptw *tw, int rearm) 627 { 628 629 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 630 INP_WLOCK_ASSERT(tw->tw_inpcb); 631 632 TW_WLOCK(V_tw_lock); 633 if (rearm) 634 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl); 635 tw->tw_time = ticks + 2 * tcp_msl; 636 TAILQ_INSERT_TAIL(&V_twq_2msl, tw, tw_2msl); 637 TW_WUNLOCK(V_tw_lock); 638 } 639 640 static void 641 tcp_tw_2msl_stop(struct tcptw *tw, int reuse) 642 { 643 struct ucred *cred; 644 struct inpcb *inp; 645 int released; 646 647 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 648 649 TW_WLOCK(V_tw_lock); 650 inp = tw->tw_inpcb; 651 tw->tw_inpcb = NULL; 652 653 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl); 654 cred = tw->tw_cred; 655 tw->tw_cred = NULL; 656 TW_WUNLOCK(V_tw_lock); 657 658 if (cred != NULL) 659 crfree(cred); 660 661 released = in_pcbrele_wlocked(inp); 662 KASSERT(!released, ("%s: inp should not be released here", __func__)); 663 664 if (!reuse) 665 uma_zfree(V_tcptw_zone, tw); 666 TCPSTATES_DEC(TCPS_TIME_WAIT); 667 } 668 669 struct tcptw * 670 tcp_tw_2msl_scan(int reuse) 671 { 672 struct tcptw *tw; 673 struct inpcb *inp; 674 675 #ifdef INVARIANTS 676 if (reuse) { 677 /* 678 * Exclusive pcbinfo lock is not required in reuse case even if 679 * two inpcb locks can be acquired simultaneously: 680 * - the inpcb transitioning to TIME_WAIT state in 681 * tcp_tw_start(), 682 * - the inpcb closed by tcp_twclose(). 683 * 684 * It is because only inpcbs in FIN_WAIT2 or CLOSING states can 685 * transition in TIME_WAIT state. Then a pcbcb cannot be in 686 * TIME_WAIT list and transitioning to TIME_WAIT state at same 687 * time. 688 */ 689 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 690 } 691 #endif 692 693 for (;;) { 694 TW_RLOCK(V_tw_lock); 695 tw = TAILQ_FIRST(&V_twq_2msl); 696 if (tw == NULL || (!reuse && (tw->tw_time - ticks) > 0)) { 697 TW_RUNLOCK(V_tw_lock); 698 break; 699 } 700 KASSERT(tw->tw_inpcb != NULL, ("%s: tw->tw_inpcb == NULL", 701 __func__)); 702 703 inp = tw->tw_inpcb; 704 in_pcbref(inp); 705 TW_RUNLOCK(V_tw_lock); 706 707 if (INP_INFO_TRY_RLOCK(&V_tcbinfo)) { 708 709 INP_WLOCK(inp); 710 tw = intotw(inp); 711 if (in_pcbrele_wlocked(inp)) { 712 KASSERT(tw == NULL, ("%s: held last inp " 713 "reference but tw not NULL", __func__)); 714 INP_INFO_RUNLOCK(&V_tcbinfo); 715 continue; 716 } 717 718 if (tw == NULL) { 719 /* tcp_twclose() has already been called */ 720 INP_WUNLOCK(inp); 721 INP_INFO_RUNLOCK(&V_tcbinfo); 722 continue; 723 } 724 725 tcp_twclose(tw, reuse); 726 INP_INFO_RUNLOCK(&V_tcbinfo); 727 if (reuse) 728 return tw; 729 } else { 730 /* INP_INFO lock is busy, continue later. */ 731 INP_WLOCK(inp); 732 if (!in_pcbrele_wlocked(inp)) 733 INP_WUNLOCK(inp); 734 break; 735 } 736 } 737 738 return NULL; 739 } 740