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 #ifndef INVARIANTS 51 #include <sys/syslog.h> 52 #endif 53 #include <sys/protosw.h> 54 #include <sys/random.h> 55 56 #include <vm/uma.h> 57 58 #include <net/route.h> 59 #include <net/if.h> 60 #include <net/if_var.h> 61 #include <net/vnet.h> 62 63 #include <netinet/in.h> 64 #include <netinet/in_pcb.h> 65 #include <netinet/in_systm.h> 66 #include <netinet/in_var.h> 67 #include <netinet/ip.h> 68 #include <netinet/ip_icmp.h> 69 #include <netinet/ip_var.h> 70 #ifdef INET6 71 #include <netinet/ip6.h> 72 #include <netinet6/in6_pcb.h> 73 #include <netinet6/ip6_var.h> 74 #include <netinet6/scope6_var.h> 75 #include <netinet6/nd6.h> 76 #endif 77 #include <netinet/tcp.h> 78 #include <netinet/tcp_fsm.h> 79 #include <netinet/tcp_seq.h> 80 #include <netinet/tcp_timer.h> 81 #include <netinet/tcp_var.h> 82 #ifdef INET6 83 #include <netinet6/tcp6_var.h> 84 #endif 85 #include <netinet/tcpip.h> 86 #ifdef TCPDEBUG 87 #include <netinet/tcp_debug.h> 88 #endif 89 #ifdef INET6 90 #include <netinet6/ip6protosw.h> 91 #endif 92 93 #include <machine/in_cksum.h> 94 95 #include <security/mac/mac_framework.h> 96 97 static VNET_DEFINE(uma_zone_t, tcptw_zone); 98 #define V_tcptw_zone VNET(tcptw_zone) 99 static int maxtcptw; 100 101 /* 102 * The timed wait queue contains references to each of the TCP sessions 103 * currently in the TIME_WAIT state. The queue pointers, including the 104 * queue pointers in each tcptw structure, are protected using the global 105 * timewait lock, which must be held over queue iteration and modification. 106 * 107 * Rules on tcptw usage: 108 * - a inpcb is always freed _after_ its tcptw 109 * - a tcptw relies on its inpcb reference counting for memory stability 110 * - a tcptw is dereferenceable only while its inpcb is locked 111 */ 112 static VNET_DEFINE(TAILQ_HEAD(, tcptw), twq_2msl); 113 #define V_twq_2msl VNET(twq_2msl) 114 115 /* Global timewait lock */ 116 static VNET_DEFINE(struct rwlock, tw_lock); 117 #define V_tw_lock VNET(tw_lock) 118 119 #define TW_LOCK_INIT(tw, d) rw_init_flags(&(tw), (d), 0) 120 #define TW_LOCK_DESTROY(tw) rw_destroy(&(tw)) 121 #define TW_RLOCK(tw) rw_rlock(&(tw)) 122 #define TW_WLOCK(tw) rw_wlock(&(tw)) 123 #define TW_RUNLOCK(tw) rw_runlock(&(tw)) 124 #define TW_WUNLOCK(tw) rw_wunlock(&(tw)) 125 #define TW_LOCK_ASSERT(tw) rw_assert(&(tw), RA_LOCKED) 126 #define TW_RLOCK_ASSERT(tw) rw_assert(&(tw), RA_RLOCKED) 127 #define TW_WLOCK_ASSERT(tw) rw_assert(&(tw), RA_WLOCKED) 128 #define TW_UNLOCK_ASSERT(tw) rw_assert(&(tw), RA_UNLOCKED) 129 130 static void tcp_tw_2msl_reset(struct tcptw *, int); 131 static void tcp_tw_2msl_stop(struct tcptw *, int); 132 static int tcp_twrespond(struct tcptw *, int); 133 134 static int 135 tcptw_auto_size(void) 136 { 137 int halfrange; 138 139 /* 140 * Max out at half the ephemeral port range so that TIME_WAIT 141 * sockets don't tie up too many ephemeral ports. 142 */ 143 if (V_ipport_lastauto > V_ipport_firstauto) 144 halfrange = (V_ipport_lastauto - V_ipport_firstauto) / 2; 145 else 146 halfrange = (V_ipport_firstauto - V_ipport_lastauto) / 2; 147 /* Protect against goofy port ranges smaller than 32. */ 148 return (imin(imax(halfrange, 32), maxsockets / 5)); 149 } 150 151 static int 152 sysctl_maxtcptw(SYSCTL_HANDLER_ARGS) 153 { 154 int error, new; 155 156 if (maxtcptw == 0) 157 new = tcptw_auto_size(); 158 else 159 new = maxtcptw; 160 error = sysctl_handle_int(oidp, &new, 0, req); 161 if (error == 0 && req->newptr) 162 if (new >= 32) { 163 maxtcptw = new; 164 uma_zone_set_max(V_tcptw_zone, maxtcptw); 165 } 166 return (error); 167 } 168 169 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, maxtcptw, CTLTYPE_INT|CTLFLAG_RW, 170 &maxtcptw, 0, sysctl_maxtcptw, "IU", 171 "Maximum number of compressed TCP TIME_WAIT entries"); 172 173 VNET_DEFINE(int, nolocaltimewait) = 0; 174 #define V_nolocaltimewait VNET(nolocaltimewait) 175 SYSCTL_INT(_net_inet_tcp, OID_AUTO, nolocaltimewait, CTLFLAG_VNET | CTLFLAG_RW, 176 &VNET_NAME(nolocaltimewait), 0, 177 "Do not create compressed TCP TIME_WAIT entries for local connections"); 178 179 void 180 tcp_tw_zone_change(void) 181 { 182 183 if (maxtcptw == 0) 184 uma_zone_set_max(V_tcptw_zone, tcptw_auto_size()); 185 } 186 187 void 188 tcp_tw_init(void) 189 { 190 191 V_tcptw_zone = uma_zcreate("tcptw", sizeof(struct tcptw), 192 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 193 TUNABLE_INT_FETCH("net.inet.tcp.maxtcptw", &maxtcptw); 194 if (maxtcptw == 0) 195 uma_zone_set_max(V_tcptw_zone, tcptw_auto_size()); 196 else 197 uma_zone_set_max(V_tcptw_zone, maxtcptw); 198 TAILQ_INIT(&V_twq_2msl); 199 TW_LOCK_INIT(V_tw_lock, "tcptw"); 200 } 201 202 #ifdef VIMAGE 203 void 204 tcp_tw_destroy(void) 205 { 206 struct tcptw *tw; 207 208 INP_INFO_RLOCK(&V_tcbinfo); 209 while ((tw = TAILQ_FIRST(&V_twq_2msl)) != NULL) 210 tcp_twclose(tw, 0); 211 INP_INFO_RUNLOCK(&V_tcbinfo); 212 213 TW_LOCK_DESTROY(V_tw_lock); 214 uma_zdestroy(V_tcptw_zone); 215 } 216 #endif 217 218 /* 219 * Move a TCP connection into TIME_WAIT state. 220 * tcbinfo is locked. 221 * inp is locked, and is unlocked before returning. 222 */ 223 void 224 tcp_twstart(struct tcpcb *tp) 225 { 226 struct tcptw *tw; 227 struct inpcb *inp = tp->t_inpcb; 228 int acknow; 229 struct socket *so; 230 #ifdef INET6 231 int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6; 232 #endif 233 234 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 235 INP_WLOCK_ASSERT(inp); 236 237 /* A dropped inp should never transition to TIME_WAIT state. */ 238 KASSERT((inp->inp_flags & INP_DROPPED) == 0, ("tcp_twstart: " 239 "(inp->inp_flags & INP_DROPPED) != 0")); 240 241 if (V_nolocaltimewait) { 242 int error = 0; 243 #ifdef INET6 244 if (isipv6) 245 error = in6_localaddr(&inp->in6p_faddr); 246 #endif 247 #if defined(INET6) && defined(INET) 248 else 249 #endif 250 #ifdef INET 251 error = in_localip(inp->inp_faddr); 252 #endif 253 if (error) { 254 tp = tcp_close(tp); 255 if (tp != NULL) 256 INP_WUNLOCK(inp); 257 return; 258 } 259 } 260 261 262 /* 263 * For use only by DTrace. We do not reference the state 264 * after this point so modifying it in place is not a problem. 265 */ 266 tcp_state_change(tp, TCPS_TIME_WAIT); 267 268 tw = uma_zalloc(V_tcptw_zone, M_NOWAIT); 269 if (tw == NULL) { 270 /* 271 * Reached limit on total number of TIMEWAIT connections 272 * allowed. Remove a connection from TIMEWAIT queue in LRU 273 * fashion to make room for this connection. 274 * 275 * XXX: Check if it possible to always have enough room 276 * in advance based on guarantees provided by uma_zalloc(). 277 */ 278 tw = tcp_tw_2msl_scan(1); 279 if (tw == NULL) { 280 tp = tcp_close(tp); 281 if (tp != NULL) 282 INP_WUNLOCK(inp); 283 return; 284 } 285 } 286 /* 287 * The tcptw will hold a reference on its inpcb until tcp_twclose 288 * is called 289 */ 290 tw->tw_inpcb = inp; 291 in_pcbref(inp); /* Reference from tw */ 292 293 /* 294 * Recover last window size sent. 295 */ 296 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt)) 297 tw->last_win = (tp->rcv_adv - tp->rcv_nxt) >> tp->rcv_scale; 298 else 299 tw->last_win = 0; 300 301 /* 302 * Set t_recent if timestamps are used on the connection. 303 */ 304 if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) == 305 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) { 306 tw->t_recent = tp->ts_recent; 307 tw->ts_offset = tp->ts_offset; 308 } else { 309 tw->t_recent = 0; 310 tw->ts_offset = 0; 311 } 312 313 tw->snd_nxt = tp->snd_nxt; 314 tw->rcv_nxt = tp->rcv_nxt; 315 tw->iss = tp->iss; 316 tw->irs = tp->irs; 317 tw->t_starttime = tp->t_starttime; 318 tw->tw_time = 0; 319 320 /* XXX 321 * If this code will 322 * be used for fin-wait-2 state also, then we may need 323 * a ts_recent from the last segment. 324 */ 325 acknow = tp->t_flags & TF_ACKNOW; 326 327 /* 328 * First, discard tcpcb state, which includes stopping its timers and 329 * freeing it. tcp_discardcb() used to also release the inpcb, but 330 * that work is now done in the caller. 331 * 332 * Note: soisdisconnected() call used to be made in tcp_discardcb(), 333 * and might not be needed here any longer. 334 */ 335 tcp_discardcb(tp); 336 so = inp->inp_socket; 337 soisdisconnected(so); 338 tw->tw_cred = crhold(so->so_cred); 339 SOCK_LOCK(so); 340 tw->tw_so_options = so->so_options; 341 SOCK_UNLOCK(so); 342 if (acknow) 343 tcp_twrespond(tw, TH_ACK); 344 inp->inp_ppcb = tw; 345 inp->inp_flags |= INP_TIMEWAIT; 346 TCPSTATES_INC(TCPS_TIME_WAIT); 347 tcp_tw_2msl_reset(tw, 0); 348 349 /* 350 * If the inpcb owns the sole reference to the socket, then we can 351 * detach and free the socket as it is not needed in time wait. 352 */ 353 if (inp->inp_flags & INP_SOCKREF) { 354 KASSERT(so->so_state & SS_PROTOREF, 355 ("tcp_twstart: !SS_PROTOREF")); 356 inp->inp_flags &= ~INP_SOCKREF; 357 INP_WUNLOCK(inp); 358 SOCK_LOCK(so); 359 so->so_state &= ~SS_PROTOREF; 360 sofree(so); 361 } else 362 INP_WUNLOCK(inp); 363 } 364 365 /* 366 * Returns 1 if the TIME_WAIT state was killed and we should start over, 367 * looking for a pcb in the listen state. Returns 0 otherwise. 368 */ 369 int 370 tcp_twcheck(struct inpcb *inp, struct tcpopt *to __unused, struct tcphdr *th, 371 struct mbuf *m, int tlen) 372 { 373 struct tcptw *tw; 374 int thflags; 375 tcp_seq seq; 376 377 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 378 INP_WLOCK_ASSERT(inp); 379 380 /* 381 * XXXRW: Time wait state for inpcb has been recycled, but inpcb is 382 * still present. This is undesirable, but temporarily necessary 383 * until we work out how to handle inpcb's who's timewait state has 384 * been removed. 385 */ 386 tw = intotw(inp); 387 if (tw == NULL) 388 goto drop; 389 390 thflags = th->th_flags; 391 392 /* 393 * NOTE: for FIN_WAIT_2 (to be added later), 394 * must validate sequence number before accepting RST 395 */ 396 397 /* 398 * If the segment contains RST: 399 * Drop the segment - see Stevens, vol. 2, p. 964 and 400 * RFC 1337. 401 */ 402 if (thflags & TH_RST) 403 goto drop; 404 405 #if 0 406 /* PAWS not needed at the moment */ 407 /* 408 * RFC 1323 PAWS: If we have a timestamp reply on this segment 409 * and it's less than ts_recent, drop it. 410 */ 411 if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent && 412 TSTMP_LT(to.to_tsval, tp->ts_recent)) { 413 if ((thflags & TH_ACK) == 0) 414 goto drop; 415 goto ack; 416 } 417 /* 418 * ts_recent is never updated because we never accept new segments. 419 */ 420 #endif 421 422 /* 423 * If a new connection request is received 424 * while in TIME_WAIT, drop the old connection 425 * and start over if the sequence numbers 426 * are above the previous ones. 427 */ 428 if ((thflags & TH_SYN) && SEQ_GT(th->th_seq, tw->rcv_nxt)) { 429 tcp_twclose(tw, 0); 430 return (1); 431 } 432 433 /* 434 * Drop the segment if it does not contain an ACK. 435 */ 436 if ((thflags & TH_ACK) == 0) 437 goto drop; 438 439 /* 440 * Reset the 2MSL timer if this is a duplicate FIN. 441 */ 442 if (thflags & TH_FIN) { 443 seq = th->th_seq + tlen + (thflags & TH_SYN ? 1 : 0); 444 if (seq + 1 == tw->rcv_nxt) 445 tcp_tw_2msl_reset(tw, 1); 446 } 447 448 /* 449 * Acknowledge the segment if it has data or is not a duplicate ACK. 450 */ 451 if (thflags != TH_ACK || tlen != 0 || 452 th->th_seq != tw->rcv_nxt || th->th_ack != tw->snd_nxt) 453 tcp_twrespond(tw, TH_ACK); 454 drop: 455 INP_WUNLOCK(inp); 456 m_freem(m); 457 return (0); 458 } 459 460 void 461 tcp_twclose(struct tcptw *tw, int reuse) 462 { 463 struct socket *so; 464 struct inpcb *inp; 465 466 /* 467 * At this point, we are in one of two situations: 468 * 469 * (1) We have no socket, just an inpcb<->twtcp pair. We can free 470 * all state. 471 * 472 * (2) We have a socket -- if we own a reference, release it and 473 * notify the socket layer. 474 */ 475 inp = tw->tw_inpcb; 476 KASSERT((inp->inp_flags & INP_TIMEWAIT), ("tcp_twclose: !timewait")); 477 KASSERT(intotw(inp) == tw, ("tcp_twclose: inp_ppcb != tw")); 478 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); /* in_pcbfree() */ 479 INP_WLOCK_ASSERT(inp); 480 481 tcp_tw_2msl_stop(tw, reuse); 482 inp->inp_ppcb = NULL; 483 in_pcbdrop(inp); 484 485 so = inp->inp_socket; 486 if (so != NULL) { 487 /* 488 * If there's a socket, handle two cases: first, we own a 489 * strong reference, which we will now release, or we don't 490 * in which case another reference exists (XXXRW: think 491 * about this more), and we don't need to take action. 492 */ 493 if (inp->inp_flags & INP_SOCKREF) { 494 inp->inp_flags &= ~INP_SOCKREF; 495 INP_WUNLOCK(inp); 496 SOCK_LOCK(so); 497 KASSERT(so->so_state & SS_PROTOREF, 498 ("tcp_twclose: INP_SOCKREF && !SS_PROTOREF")); 499 so->so_state &= ~SS_PROTOREF; 500 sofree(so); 501 } else { 502 /* 503 * If we don't own the only reference, the socket and 504 * inpcb need to be left around to be handled by 505 * tcp_usr_detach() later. 506 */ 507 INP_WUNLOCK(inp); 508 } 509 } else { 510 /* 511 * The socket has been already cleaned-up for us, only free the 512 * inpcb. 513 */ 514 in_pcbfree(inp); 515 } 516 TCPSTAT_INC(tcps_closed); 517 } 518 519 static int 520 tcp_twrespond(struct tcptw *tw, int flags) 521 { 522 struct inpcb *inp = tw->tw_inpcb; 523 #if defined(INET6) || defined(INET) 524 struct tcphdr *th = NULL; 525 #endif 526 struct mbuf *m; 527 #ifdef INET 528 struct ip *ip = NULL; 529 #endif 530 u_int hdrlen, optlen; 531 int error = 0; /* Keep compiler happy */ 532 struct tcpopt to; 533 #ifdef INET6 534 struct ip6_hdr *ip6 = NULL; 535 int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6; 536 #endif 537 hdrlen = 0; /* Keep compiler happy */ 538 539 INP_WLOCK_ASSERT(inp); 540 541 m = m_gethdr(M_NOWAIT, MT_DATA); 542 if (m == NULL) 543 return (ENOBUFS); 544 m->m_data += max_linkhdr; 545 546 #ifdef MAC 547 mac_inpcb_create_mbuf(inp, m); 548 #endif 549 550 #ifdef INET6 551 if (isipv6) { 552 hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 553 ip6 = mtod(m, struct ip6_hdr *); 554 th = (struct tcphdr *)(ip6 + 1); 555 tcpip_fillheaders(inp, ip6, th); 556 } 557 #endif 558 #if defined(INET6) && defined(INET) 559 else 560 #endif 561 #ifdef INET 562 { 563 hdrlen = sizeof(struct tcpiphdr); 564 ip = mtod(m, struct ip *); 565 th = (struct tcphdr *)(ip + 1); 566 tcpip_fillheaders(inp, ip, th); 567 } 568 #endif 569 to.to_flags = 0; 570 571 /* 572 * Send a timestamp and echo-reply if both our side and our peer 573 * have sent timestamps in our SYN's and this is not a RST. 574 */ 575 if (tw->t_recent && flags == TH_ACK) { 576 to.to_flags |= TOF_TS; 577 to.to_tsval = tcp_ts_getticks() + tw->ts_offset; 578 to.to_tsecr = tw->t_recent; 579 } 580 optlen = tcp_addoptions(&to, (u_char *)(th + 1)); 581 582 m->m_len = hdrlen + optlen; 583 m->m_pkthdr.len = m->m_len; 584 585 KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small")); 586 587 th->th_seq = htonl(tw->snd_nxt); 588 th->th_ack = htonl(tw->rcv_nxt); 589 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 590 th->th_flags = flags; 591 th->th_win = htons(tw->last_win); 592 593 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 594 #ifdef INET6 595 if (isipv6) { 596 m->m_pkthdr.csum_flags = CSUM_TCP_IPV6; 597 th->th_sum = in6_cksum_pseudo(ip6, 598 sizeof(struct tcphdr) + optlen, IPPROTO_TCP, 0); 599 ip6->ip6_hlim = in6_selecthlim(inp, NULL); 600 error = ip6_output(m, inp->in6p_outputopts, NULL, 601 (tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp); 602 } 603 #endif 604 #if defined(INET6) && defined(INET) 605 else 606 #endif 607 #ifdef INET 608 { 609 m->m_pkthdr.csum_flags = CSUM_TCP; 610 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 611 htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP)); 612 ip->ip_len = htons(m->m_pkthdr.len); 613 if (V_path_mtu_discovery) 614 ip->ip_off |= htons(IP_DF); 615 error = ip_output(m, inp->inp_options, NULL, 616 ((tw->tw_so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0), 617 NULL, inp); 618 } 619 #endif 620 if (flags & TH_ACK) 621 TCPSTAT_INC(tcps_sndacks); 622 else 623 TCPSTAT_INC(tcps_sndctrl); 624 TCPSTAT_INC(tcps_sndtotal); 625 return (error); 626 } 627 628 static void 629 tcp_tw_2msl_reset(struct tcptw *tw, int rearm) 630 { 631 632 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 633 INP_WLOCK_ASSERT(tw->tw_inpcb); 634 635 TW_WLOCK(V_tw_lock); 636 if (rearm) 637 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl); 638 tw->tw_time = ticks + 2 * tcp_msl; 639 TAILQ_INSERT_TAIL(&V_twq_2msl, tw, tw_2msl); 640 TW_WUNLOCK(V_tw_lock); 641 } 642 643 static void 644 tcp_tw_2msl_stop(struct tcptw *tw, int reuse) 645 { 646 struct ucred *cred; 647 struct inpcb *inp; 648 int released; 649 650 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 651 652 TW_WLOCK(V_tw_lock); 653 inp = tw->tw_inpcb; 654 tw->tw_inpcb = NULL; 655 656 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl); 657 cred = tw->tw_cred; 658 tw->tw_cred = NULL; 659 TW_WUNLOCK(V_tw_lock); 660 661 if (cred != NULL) 662 crfree(cred); 663 664 released = in_pcbrele_wlocked(inp); 665 KASSERT(!released, ("%s: inp should not be released here", __func__)); 666 667 if (!reuse) 668 uma_zfree(V_tcptw_zone, tw); 669 TCPSTATES_DEC(TCPS_TIME_WAIT); 670 } 671 672 struct tcptw * 673 tcp_tw_2msl_scan(int reuse) 674 { 675 struct tcptw *tw; 676 struct inpcb *inp; 677 678 #ifdef INVARIANTS 679 if (reuse) { 680 /* 681 * Exclusive pcbinfo lock is not required in reuse case even if 682 * two inpcb locks can be acquired simultaneously: 683 * - the inpcb transitioning to TIME_WAIT state in 684 * tcp_tw_start(), 685 * - the inpcb closed by tcp_twclose(). 686 * 687 * It is because only inpcbs in FIN_WAIT2 or CLOSING states can 688 * transition in TIME_WAIT state. Then a pcbcb cannot be in 689 * TIME_WAIT list and transitioning to TIME_WAIT state at same 690 * time. 691 */ 692 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 693 } 694 #endif 695 696 for (;;) { 697 TW_RLOCK(V_tw_lock); 698 tw = TAILQ_FIRST(&V_twq_2msl); 699 if (tw == NULL || (!reuse && (tw->tw_time - ticks) > 0)) { 700 TW_RUNLOCK(V_tw_lock); 701 break; 702 } 703 KASSERT(tw->tw_inpcb != NULL, ("%s: tw->tw_inpcb == NULL", 704 __func__)); 705 706 inp = tw->tw_inpcb; 707 in_pcbref(inp); 708 TW_RUNLOCK(V_tw_lock); 709 710 if (INP_INFO_TRY_RLOCK(&V_tcbinfo)) { 711 712 INP_WLOCK(inp); 713 tw = intotw(inp); 714 if (in_pcbrele_wlocked(inp)) { 715 if (__predict_true(tw == NULL)) { 716 INP_INFO_RUNLOCK(&V_tcbinfo); 717 continue; 718 } else { 719 /* This should not happen as in TIMEWAIT 720 * state the inp should not be destroyed 721 * before its tcptw. If INVARIANTS is 722 * defined panic. 723 */ 724 #ifdef INVARIANTS 725 panic("%s: Panic before an infinite " 726 "loop: INP_TIMEWAIT && (INP_FREED " 727 "|| inp last reference) && tw != " 728 "NULL", __func__); 729 #else 730 log(LOG_ERR, "%s: Avoid an infinite " 731 "loop: INP_TIMEWAIT && (INP_FREED " 732 "|| inp last reference) && tw != " 733 "NULL", __func__); 734 #endif 735 INP_INFO_RUNLOCK(&V_tcbinfo); 736 break; 737 } 738 } 739 740 if (tw == NULL) { 741 /* tcp_twclose() has already been called */ 742 INP_WUNLOCK(inp); 743 INP_INFO_RUNLOCK(&V_tcbinfo); 744 continue; 745 } 746 747 tcp_twclose(tw, reuse); 748 INP_INFO_RUNLOCK(&V_tcbinfo); 749 if (reuse) 750 return tw; 751 } else { 752 /* INP_INFO lock is busy, continue later. */ 753 INP_WLOCK(inp); 754 if (!in_pcbrele_wlocked(inp)) 755 INP_WUNLOCK(inp); 756 break; 757 } 758 } 759 760 return NULL; 761 } 762