Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/netinet/tcp_timewait.c
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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 * 4. 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: releng/10.3/sys/netinet/tcp_timewait.c 282826 2015-05-13 00:28:36Z gnn $"); 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/vnet.h> 58 59 #include <netinet/in.h> 60 #include <netinet/in_pcb.h> 61 #include <netinet/in_systm.h> 62 #include <netinet/in_var.h> 63 #include <netinet/ip.h> 64 #include <netinet/ip_icmp.h> 65 #include <netinet/ip_var.h> 66 #ifdef INET6 67 #include <netinet/ip6.h> 68 #include <netinet6/in6_pcb.h> 69 #include <netinet6/ip6_var.h> 70 #include <netinet6/scope6_var.h> 71 #include <netinet6/nd6.h> 72 #endif 73 #include <netinet/tcp.h> 74 #include <netinet/tcp_fsm.h> 75 #include <netinet/tcp_seq.h> 76 #include <netinet/tcp_timer.h> 77 #include <netinet/tcp_var.h> 78 #ifdef INET6 79 #include <netinet6/tcp6_var.h> 80 #endif 81 #include <netinet/tcpip.h> 82 #ifdef TCPDEBUG 83 #include <netinet/tcp_debug.h> 84 #endif 85 #ifdef INET6 86 #include <netinet6/ip6protosw.h> 87 #endif 88 89 #include <machine/in_cksum.h> 90 91 #include <security/mac/mac_framework.h> 92 93 static VNET_DEFINE(uma_zone_t, tcptw_zone); 94 #define V_tcptw_zone VNET(tcptw_zone) 95 static int maxtcptw; 96 97 /* 98 * The timed wait queue contains references to each of the TCP sessions 99 * currently in the TIME_WAIT state. The queue pointers, including the 100 * queue pointers in each tcptw structure, are protected using the global 101 * timewait lock, which must be held over queue iteration and modification. 102 * 103 * Rules on tcptw usage: 104 * - a inpcb is always freed _after_ its tcptw 105 * - a tcptw relies on its inpcb reference counting for memory stability 106 * - a tcptw is dereferenceable only while its inpcb is locked 107 */ 108 static VNET_DEFINE(TAILQ_HEAD(, tcptw), twq_2msl); 109 #define V_twq_2msl VNET(twq_2msl) 110 111 /* Global timewait lock */ 112 static VNET_DEFINE(struct rwlock, tw_lock); 113 #define V_tw_lock VNET(tw_lock) 114 115 #define TW_LOCK_INIT(tw, d) rw_init_flags(&(tw), (d), 0) 116 #define TW_LOCK_DESTROY(tw) rw_destroy(&(tw)) 117 #define TW_RLOCK(tw) rw_rlock(&(tw)) 118 #define TW_WLOCK(tw) rw_wlock(&(tw)) 119 #define TW_RUNLOCK(tw) rw_runlock(&(tw)) 120 #define TW_WUNLOCK(tw) rw_wunlock(&(tw)) 121 #define TW_LOCK_ASSERT(tw) rw_assert(&(tw), RA_LOCKED) 122 #define TW_RLOCK_ASSERT(tw) rw_assert(&(tw), RA_RLOCKED) 123 #define TW_WLOCK_ASSERT(tw) rw_assert(&(tw), RA_WLOCKED) 124 #define TW_UNLOCK_ASSERT(tw) rw_assert(&(tw), RA_UNLOCKED) 125 126 static void tcp_tw_2msl_reset(struct tcptw *, int); 127 static void tcp_tw_2msl_stop(struct tcptw *, int); 128 static int tcp_twrespond(struct tcptw *, int); 129 130 static int 131 tcptw_auto_size(void) 132 { 133 int halfrange; 134 135 /* 136 * Max out at half the ephemeral port range so that TIME_WAIT 137 * sockets don't tie up too many ephemeral ports. 138 */ 139 if (V_ipport_lastauto > V_ipport_firstauto) 140 halfrange = (V_ipport_lastauto - V_ipport_firstauto) / 2; 141 else 142 halfrange = (V_ipport_firstauto - V_ipport_lastauto) / 2; 143 /* Protect against goofy port ranges smaller than 32. */ 144 return (imin(imax(halfrange, 32), maxsockets / 5)); 145 } 146 147 static int 148 sysctl_maxtcptw(SYSCTL_HANDLER_ARGS) 149 { 150 int error, new; 151 152 if (maxtcptw == 0) 153 new = tcptw_auto_size(); 154 else 155 new = maxtcptw; 156 error = sysctl_handle_int(oidp, &new, 0, req); 157 if (error == 0 && req->newptr) 158 if (new >= 32) { 159 maxtcptw = new; 160 uma_zone_set_max(V_tcptw_zone, maxtcptw); 161 } 162 return (error); 163 } 164 165 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, maxtcptw, CTLTYPE_INT|CTLFLAG_RW, 166 &maxtcptw, 0, sysctl_maxtcptw, "IU", 167 "Maximum number of compressed TCP TIME_WAIT entries"); 168 169 VNET_DEFINE(int, nolocaltimewait) = 0; 170 #define V_nolocaltimewait VNET(nolocaltimewait) 171 SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, nolocaltimewait, CTLFLAG_RW, 172 &VNET_NAME(nolocaltimewait), 0, 173 "Do not create compressed TCP TIME_WAIT entries for local connections"); 174 175 void 176 tcp_tw_zone_change(void) 177 { 178 179 if (maxtcptw == 0) 180 uma_zone_set_max(V_tcptw_zone, tcptw_auto_size()); 181 } 182 183 void 184 tcp_tw_init(void) 185 { 186 187 V_tcptw_zone = uma_zcreate("tcptw", sizeof(struct tcptw), 188 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 189 TUNABLE_INT_FETCH("net.inet.tcp.maxtcptw", &maxtcptw); 190 if (maxtcptw == 0) 191 uma_zone_set_max(V_tcptw_zone, tcptw_auto_size()); 192 else 193 uma_zone_set_max(V_tcptw_zone, maxtcptw); 194 TAILQ_INIT(&V_twq_2msl); 195 TW_LOCK_INIT(V_tw_lock, "tcptw"); 196 } 197 198 #ifdef VIMAGE 199 void 200 tcp_tw_destroy(void) 201 { 202 struct tcptw *tw; 203 204 INP_INFO_WLOCK(&V_tcbinfo); 205 while ((tw = TAILQ_FIRST(&V_twq_2msl)) != NULL) 206 tcp_twclose(tw, 0); 207 INP_INFO_WUNLOCK(&V_tcbinfo); 208 209 TW_LOCK_DESTROY(V_tw_lock); 210 uma_zdestroy(V_tcptw_zone); 211 } 212 #endif 213 214 /* 215 * Move a TCP connection into TIME_WAIT state. 216 * tcbinfo is locked. 217 * inp is locked, and is unlocked before returning. 218 */ 219 void 220 tcp_twstart(struct tcpcb *tp) 221 { 222 struct tcptw *tw; 223 struct inpcb *inp = tp->t_inpcb; 224 int acknow; 225 struct socket *so; 226 #ifdef INET6 227 int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6; 228 #endif 229 230 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 231 INP_WLOCK_ASSERT(inp); 232 233 if (V_nolocaltimewait) { 234 int error = 0; 235 #ifdef INET6 236 if (isipv6) 237 error = in6_localaddr(&inp->in6p_faddr); 238 #endif 239 #if defined(INET6) && defined(INET) 240 else 241 #endif 242 #ifdef INET 243 error = in_localip(inp->inp_faddr); 244 #endif 245 if (error) { 246 tp = tcp_close(tp); 247 if (tp != NULL) 248 INP_WUNLOCK(inp); 249 return; 250 } 251 } 252 253 254 /* 255 * For use only by DTrace. We do not reference the state 256 * after this point so modifying it in place is not a problem. 257 */ 258 tcp_state_change(tp, TCPS_TIME_WAIT); 259 260 tw = uma_zalloc(V_tcptw_zone, M_NOWAIT); 261 if (tw == NULL) { 262 /* 263 * Reached limit on total number of TIMEWAIT connections 264 * allowed. Remove a connection from TIMEWAIT queue in LRU 265 * fashion to make room for this connection. 266 * 267 * pcbinfo lock is needed here to prevent deadlock as 268 * two inpcb locks can be acquired simultaneously. 269 */ 270 tw = tcp_tw_2msl_scan(1); 271 if (tw == NULL) { 272 tp = tcp_close(tp); 273 if (tp != NULL) 274 INP_WUNLOCK(inp); 275 return; 276 } 277 } 278 /* 279 * The tcptw will hold a reference on its inpcb until tcp_twclose 280 * is called 281 */ 282 tw->tw_inpcb = inp; 283 in_pcbref(inp); /* Reference from tw */ 284 285 /* 286 * Recover last window size sent. 287 */ 288 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt)) 289 tw->last_win = (tp->rcv_adv - tp->rcv_nxt) >> tp->rcv_scale; 290 else 291 tw->last_win = 0; 292 293 /* 294 * Set t_recent if timestamps are used on the connection. 295 */ 296 if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) == 297 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) { 298 tw->t_recent = tp->ts_recent; 299 tw->ts_offset = tp->ts_offset; 300 } else { 301 tw->t_recent = 0; 302 tw->ts_offset = 0; 303 } 304 305 tw->snd_nxt = tp->snd_nxt; 306 tw->rcv_nxt = tp->rcv_nxt; 307 tw->iss = tp->iss; 308 tw->irs = tp->irs; 309 tw->t_starttime = tp->t_starttime; 310 tw->tw_time = 0; 311 312 /* XXX 313 * If this code will 314 * be used for fin-wait-2 state also, then we may need 315 * a ts_recent from the last segment. 316 */ 317 acknow = tp->t_flags & TF_ACKNOW; 318 319 /* 320 * First, discard tcpcb state, which includes stopping its timers and 321 * freeing it. tcp_discardcb() used to also release the inpcb, but 322 * that work is now done in the caller. 323 * 324 * Note: soisdisconnected() call used to be made in tcp_discardcb(), 325 * and might not be needed here any longer. 326 */ 327 tcp_discardcb(tp); 328 so = inp->inp_socket; 329 soisdisconnected(so); 330 tw->tw_cred = crhold(so->so_cred); 331 SOCK_LOCK(so); 332 tw->tw_so_options = so->so_options; 333 SOCK_UNLOCK(so); 334 if (acknow) 335 tcp_twrespond(tw, TH_ACK); 336 inp->inp_ppcb = tw; 337 inp->inp_flags |= INP_TIMEWAIT; 338 tcp_tw_2msl_reset(tw, 0); 339 340 /* 341 * If the inpcb owns the sole reference to the socket, then we can 342 * detach and free the socket as it is not needed in time wait. 343 */ 344 if (inp->inp_flags & INP_SOCKREF) { 345 KASSERT(so->so_state & SS_PROTOREF, 346 ("tcp_twstart: !SS_PROTOREF")); 347 inp->inp_flags &= ~INP_SOCKREF; 348 INP_WUNLOCK(inp); 349 ACCEPT_LOCK(); 350 SOCK_LOCK(so); 351 so->so_state &= ~SS_PROTOREF; 352 sofree(so); 353 } else 354 INP_WUNLOCK(inp); 355 } 356 357 #if 0 358 /* 359 * The appromixate rate of ISN increase of Microsoft TCP stacks; 360 * the actual rate is slightly higher due to the addition of 361 * random positive increments. 362 * 363 * Most other new OSes use semi-randomized ISN values, so we 364 * do not need to worry about them. 365 */ 366 #define MS_ISN_BYTES_PER_SECOND 250000 367 368 /* 369 * Determine if the ISN we will generate has advanced beyond the last 370 * sequence number used by the previous connection. If so, indicate 371 * that it is safe to recycle this tw socket by returning 1. 372 */ 373 int 374 tcp_twrecycleable(struct tcptw *tw) 375 { 376 tcp_seq new_iss = tw->iss; 377 tcp_seq new_irs = tw->irs; 378 379 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 380 new_iss += (ticks - tw->t_starttime) * (ISN_BYTES_PER_SECOND / hz); 381 new_irs += (ticks - tw->t_starttime) * (MS_ISN_BYTES_PER_SECOND / hz); 382 383 if (SEQ_GT(new_iss, tw->snd_nxt) && SEQ_GT(new_irs, tw->rcv_nxt)) 384 return (1); 385 else 386 return (0); 387 } 388 #endif 389 390 /* 391 * Returns 1 if the TIME_WAIT state was killed and we should start over, 392 * looking for a pcb in the listen state. Returns 0 otherwise. 393 */ 394 int 395 tcp_twcheck(struct inpcb *inp, struct tcpopt *to __unused, struct tcphdr *th, 396 struct mbuf *m, int tlen) 397 { 398 struct tcptw *tw; 399 int thflags; 400 tcp_seq seq; 401 402 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 403 INP_WLOCK_ASSERT(inp); 404 405 /* 406 * XXXRW: Time wait state for inpcb has been recycled, but inpcb is 407 * still present. This is undesirable, but temporarily necessary 408 * until we work out how to handle inpcb's who's timewait state has 409 * been removed. 410 */ 411 tw = intotw(inp); 412 if (tw == NULL) 413 goto drop; 414 415 thflags = th->th_flags; 416 417 /* 418 * NOTE: for FIN_WAIT_2 (to be added later), 419 * must validate sequence number before accepting RST 420 */ 421 422 /* 423 * If the segment contains RST: 424 * Drop the segment - see Stevens, vol. 2, p. 964 and 425 * RFC 1337. 426 */ 427 if (thflags & TH_RST) 428 goto drop; 429 430 #if 0 431 /* PAWS not needed at the moment */ 432 /* 433 * RFC 1323 PAWS: If we have a timestamp reply on this segment 434 * and it's less than ts_recent, drop it. 435 */ 436 if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent && 437 TSTMP_LT(to.to_tsval, tp->ts_recent)) { 438 if ((thflags & TH_ACK) == 0) 439 goto drop; 440 goto ack; 441 } 442 /* 443 * ts_recent is never updated because we never accept new segments. 444 */ 445 #endif 446 447 /* 448 * If a new connection request is received 449 * while in TIME_WAIT, drop the old connection 450 * and start over if the sequence numbers 451 * are above the previous ones. 452 */ 453 if ((thflags & TH_SYN) && SEQ_GT(th->th_seq, tw->rcv_nxt)) { 454 tcp_twclose(tw, 0); 455 return (1); 456 } 457 458 /* 459 * Drop the segment if it does not contain an ACK. 460 */ 461 if ((thflags & TH_ACK) == 0) 462 goto drop; 463 464 /* 465 * Reset the 2MSL timer if this is a duplicate FIN. 466 */ 467 if (thflags & TH_FIN) { 468 seq = th->th_seq + tlen + (thflags & TH_SYN ? 1 : 0); 469 if (seq + 1 == tw->rcv_nxt) 470 tcp_tw_2msl_reset(tw, 1); 471 } 472 473 /* 474 * Acknowledge the segment if it has data or is not a duplicate ACK. 475 */ 476 if (thflags != TH_ACK || tlen != 0 || 477 th->th_seq != tw->rcv_nxt || th->th_ack != tw->snd_nxt) 478 tcp_twrespond(tw, TH_ACK); 479 drop: 480 INP_WUNLOCK(inp); 481 m_freem(m); 482 return (0); 483 } 484 485 void 486 tcp_twclose(struct tcptw *tw, int reuse) 487 { 488 struct socket *so; 489 struct inpcb *inp; 490 491 /* 492 * At this point, we are in one of two situations: 493 * 494 * (1) We have no socket, just an inpcb<->twtcp pair. We can free 495 * all state. 496 * 497 * (2) We have a socket -- if we own a reference, release it and 498 * notify the socket layer. 499 */ 500 inp = tw->tw_inpcb; 501 KASSERT((inp->inp_flags & INP_TIMEWAIT), ("tcp_twclose: !timewait")); 502 KASSERT(intotw(inp) == tw, ("tcp_twclose: inp_ppcb != tw")); 503 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); /* in_pcbfree() */ 504 INP_WLOCK_ASSERT(inp); 505 506 tcp_tw_2msl_stop(tw, reuse); 507 inp->inp_ppcb = NULL; 508 in_pcbdrop(inp); 509 510 so = inp->inp_socket; 511 if (so != NULL) { 512 /* 513 * If there's a socket, handle two cases: first, we own a 514 * strong reference, which we will now release, or we don't 515 * in which case another reference exists (XXXRW: think 516 * about this more), and we don't need to take action. 517 */ 518 if (inp->inp_flags & INP_SOCKREF) { 519 inp->inp_flags &= ~INP_SOCKREF; 520 INP_WUNLOCK(inp); 521 ACCEPT_LOCK(); 522 SOCK_LOCK(so); 523 KASSERT(so->so_state & SS_PROTOREF, 524 ("tcp_twclose: INP_SOCKREF && !SS_PROTOREF")); 525 so->so_state &= ~SS_PROTOREF; 526 sofree(so); 527 } else { 528 /* 529 * If we don't own the only reference, the socket and 530 * inpcb need to be left around to be handled by 531 * tcp_usr_detach() later. 532 */ 533 INP_WUNLOCK(inp); 534 } 535 } else { 536 /* 537 * The socket has been already cleaned-up for us, only free the 538 * inpcb. 539 */ 540 in_pcbfree(inp); 541 } 542 TCPSTAT_INC(tcps_closed); 543 } 544 545 static int 546 tcp_twrespond(struct tcptw *tw, int flags) 547 { 548 struct inpcb *inp = tw->tw_inpcb; 549 #if defined(INET6) || defined(INET) 550 struct tcphdr *th = NULL; 551 #endif 552 struct mbuf *m; 553 #ifdef INET 554 struct ip *ip = NULL; 555 #endif 556 u_int hdrlen, optlen; 557 int error = 0; /* Keep compiler happy */ 558 struct tcpopt to; 559 #ifdef INET6 560 struct ip6_hdr *ip6 = NULL; 561 int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6; 562 #endif 563 hdrlen = 0; /* Keep compiler happy */ 564 565 INP_WLOCK_ASSERT(inp); 566 567 m = m_gethdr(M_NOWAIT, MT_DATA); 568 if (m == NULL) 569 return (ENOBUFS); 570 m->m_data += max_linkhdr; 571 572 #ifdef MAC 573 mac_inpcb_create_mbuf(inp, m); 574 #endif 575 576 #ifdef INET6 577 if (isipv6) { 578 hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 579 ip6 = mtod(m, struct ip6_hdr *); 580 th = (struct tcphdr *)(ip6 + 1); 581 tcpip_fillheaders(inp, ip6, th); 582 } 583 #endif 584 #if defined(INET6) && defined(INET) 585 else 586 #endif 587 #ifdef INET 588 { 589 hdrlen = sizeof(struct tcpiphdr); 590 ip = mtod(m, struct ip *); 591 th = (struct tcphdr *)(ip + 1); 592 tcpip_fillheaders(inp, ip, th); 593 } 594 #endif 595 to.to_flags = 0; 596 597 /* 598 * Send a timestamp and echo-reply if both our side and our peer 599 * have sent timestamps in our SYN's and this is not a RST. 600 */ 601 if (tw->t_recent && flags == TH_ACK) { 602 to.to_flags |= TOF_TS; 603 to.to_tsval = tcp_ts_getticks() + tw->ts_offset; 604 to.to_tsecr = tw->t_recent; 605 } 606 optlen = tcp_addoptions(&to, (u_char *)(th + 1)); 607 608 m->m_len = hdrlen + optlen; 609 m->m_pkthdr.len = m->m_len; 610 611 KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small")); 612 613 th->th_seq = htonl(tw->snd_nxt); 614 th->th_ack = htonl(tw->rcv_nxt); 615 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 616 th->th_flags = flags; 617 th->th_win = htons(tw->last_win); 618 619 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 620 #ifdef INET6 621 if (isipv6) { 622 m->m_pkthdr.csum_flags = CSUM_TCP_IPV6; 623 th->th_sum = in6_cksum_pseudo(ip6, 624 sizeof(struct tcphdr) + optlen, IPPROTO_TCP, 0); 625 ip6->ip6_hlim = in6_selecthlim(inp, NULL); 626 error = ip6_output(m, inp->in6p_outputopts, NULL, 627 (tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp); 628 } 629 #endif 630 #if defined(INET6) && defined(INET) 631 else 632 #endif 633 #ifdef INET 634 { 635 m->m_pkthdr.csum_flags = CSUM_TCP; 636 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 637 htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP)); 638 ip->ip_len = htons(m->m_pkthdr.len); 639 if (V_path_mtu_discovery) 640 ip->ip_off |= htons(IP_DF); 641 error = ip_output(m, inp->inp_options, NULL, 642 ((tw->tw_so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0), 643 NULL, inp); 644 } 645 #endif 646 if (flags & TH_ACK) 647 TCPSTAT_INC(tcps_sndacks); 648 else 649 TCPSTAT_INC(tcps_sndctrl); 650 TCPSTAT_INC(tcps_sndtotal); 651 return (error); 652 } 653 654 static void 655 tcp_tw_2msl_reset(struct tcptw *tw, int rearm) 656 { 657 658 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 659 INP_WLOCK_ASSERT(tw->tw_inpcb); 660 661 TW_WLOCK(V_tw_lock); 662 if (rearm) 663 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl); 664 tw->tw_time = ticks + 2 * tcp_msl; 665 TAILQ_INSERT_TAIL(&V_twq_2msl, tw, tw_2msl); 666 TW_WUNLOCK(V_tw_lock); 667 } 668 669 static void 670 tcp_tw_2msl_stop(struct tcptw *tw, int reuse) 671 { 672 struct ucred *cred; 673 struct inpcb *inp; 674 int released; 675 676 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 677 678 TW_WLOCK(V_tw_lock); 679 inp = tw->tw_inpcb; 680 tw->tw_inpcb = NULL; 681 682 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl); 683 cred = tw->tw_cred; 684 tw->tw_cred = NULL; 685 TW_WUNLOCK(V_tw_lock); 686 687 if (cred != NULL) 688 crfree(cred); 689 690 released = in_pcbrele_wlocked(inp); 691 KASSERT(!released, ("%s: inp should not be released here", __func__)); 692 693 if (!reuse) 694 uma_zfree(V_tcptw_zone, tw); 695 } 696 697 struct tcptw * 698 tcp_tw_2msl_scan(int reuse) 699 { 700 struct tcptw *tw; 701 struct inpcb *inp; 702 703 #ifdef INVARIANTS 704 if (reuse) { 705 /* 706 * pcbinfo lock is needed in reuse case to prevent deadlock 707 * as two inpcb locks can be acquired simultaneously: 708 * - the inpcb transitioning to TIME_WAIT state in 709 * tcp_tw_start(), 710 * - the inpcb closed by tcp_twclose(). 711 */ 712 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 713 } 714 #endif 715 716 for (;;) { 717 TW_RLOCK(V_tw_lock); 718 tw = TAILQ_FIRST(&V_twq_2msl); 719 if (tw == NULL || (!reuse && (tw->tw_time - ticks) > 0)) { 720 TW_RUNLOCK(V_tw_lock); 721 break; 722 } 723 KASSERT(tw->tw_inpcb != NULL, ("%s: tw->tw_inpcb == NULL", 724 __func__)); 725 726 inp = tw->tw_inpcb; 727 in_pcbref(inp); 728 TW_RUNLOCK(V_tw_lock); 729 730 if (INP_INFO_TRY_WLOCK(&V_tcbinfo)) { 731 732 INP_WLOCK(inp); 733 tw = intotw(inp); 734 if (in_pcbrele_wlocked(inp)) { 735 KASSERT(tw == NULL, ("%s: held last inp " 736 "reference but tw not NULL", __func__)); 737 INP_INFO_WUNLOCK(&V_tcbinfo); 738 continue; 739 } 740 741 if (tw == NULL) { 742 /* tcp_twclose() has already been called */ 743 INP_WUNLOCK(inp); 744 INP_INFO_WUNLOCK(&V_tcbinfo); 745 continue; 746 } 747 748 tcp_twclose(tw, reuse); 749 INP_INFO_WUNLOCK(&V_tcbinfo); 750 if (reuse) 751 return tw; 752 } else { 753 /* INP_INFO lock is busy, continue later. */ 754 INP_WLOCK(inp); 755 if (!in_pcbrele_wlocked(inp)) 756 INP_WUNLOCK(inp); 757 break; 758 } 759 } 760 761 return NULL; 762 }
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