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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("$FreeBSD$"); 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_kdtrace.h> 65 #include <netinet/in_pcb.h> 66 #include <netinet/in_systm.h> 67 #include <netinet/in_var.h> 68 #include <netinet/ip.h> 69 #include <netinet/ip_icmp.h> 70 #include <netinet/ip_var.h> 71 #ifdef INET6 72 #include <netinet/ip6.h> 73 #include <netinet6/in6_pcb.h> 74 #include <netinet6/ip6_var.h> 75 #include <netinet6/scope6_var.h> 76 #include <netinet6/nd6.h> 77 #endif 78 #include <netinet/tcp.h> 79 #include <netinet/tcp_fsm.h> 80 #include <netinet/tcp_seq.h> 81 #include <netinet/tcp_timer.h> 82 #include <netinet/tcp_var.h> 83 #ifdef INET6 84 #include <netinet6/tcp6_var.h> 85 #endif 86 #include <netinet/tcpip.h> 87 #ifdef TCPDEBUG 88 #include <netinet/tcp_debug.h> 89 #endif 90 #ifdef INET6 91 #include <netinet6/ip6protosw.h> 92 #endif 93 94 #include <machine/in_cksum.h> 95 96 #include <security/mac/mac_framework.h> 97 98 static VNET_DEFINE(uma_zone_t, tcptw_zone); 99 #define V_tcptw_zone VNET(tcptw_zone) 100 static int maxtcptw; 101 102 /* 103 * The timed wait queue contains references to each of the TCP sessions 104 * currently in the TIME_WAIT state. The queue pointers, including the 105 * queue pointers in each tcptw structure, are protected using the global 106 * timewait lock, which must be held over queue iteration and modification. 107 * 108 * Rules on tcptw usage: 109 * - a inpcb is always freed _after_ its tcptw 110 * - a tcptw relies on its inpcb reference counting for memory stability 111 * - a tcptw is dereferenceable only while its inpcb is locked 112 */ 113 static VNET_DEFINE(TAILQ_HEAD(, tcptw), twq_2msl); 114 #define V_twq_2msl VNET(twq_2msl) 115 116 /* Global timewait lock */ 117 static VNET_DEFINE(struct rwlock, tw_lock); 118 #define V_tw_lock VNET(tw_lock) 119 120 #define TW_LOCK_INIT(tw, d) rw_init_flags(&(tw), (d), 0) 121 #define TW_LOCK_DESTROY(tw) rw_destroy(&(tw)) 122 #define TW_RLOCK(tw) rw_rlock(&(tw)) 123 #define TW_WLOCK(tw) rw_wlock(&(tw)) 124 #define TW_RUNLOCK(tw) rw_runlock(&(tw)) 125 #define TW_WUNLOCK(tw) rw_wunlock(&(tw)) 126 #define TW_LOCK_ASSERT(tw) rw_assert(&(tw), RA_LOCKED) 127 #define TW_RLOCK_ASSERT(tw) rw_assert(&(tw), RA_RLOCKED) 128 #define TW_WLOCK_ASSERT(tw) rw_assert(&(tw), RA_WLOCKED) 129 #define TW_UNLOCK_ASSERT(tw) rw_assert(&(tw), RA_UNLOCKED) 130 131 static void tcp_tw_2msl_reset(struct tcptw *, int); 132 static void tcp_tw_2msl_stop(struct tcptw *, int); 133 static int tcp_twrespond(struct tcptw *, int); 134 135 static int 136 tcptw_auto_size(void) 137 { 138 int halfrange; 139 140 /* 141 * Max out at half the ephemeral port range so that TIME_WAIT 142 * sockets don't tie up too many ephemeral ports. 143 */ 144 if (V_ipport_lastauto > V_ipport_firstauto) 145 halfrange = (V_ipport_lastauto - V_ipport_firstauto) / 2; 146 else 147 halfrange = (V_ipport_firstauto - V_ipport_lastauto) / 2; 148 /* Protect against goofy port ranges smaller than 32. */ 149 return (imin(imax(halfrange, 32), maxsockets / 5)); 150 } 151 152 static int 153 sysctl_maxtcptw(SYSCTL_HANDLER_ARGS) 154 { 155 int error, new; 156 157 if (maxtcptw == 0) 158 new = tcptw_auto_size(); 159 else 160 new = maxtcptw; 161 error = sysctl_handle_int(oidp, &new, 0, req); 162 if (error == 0 && req->newptr) 163 if (new >= 32) { 164 maxtcptw = new; 165 uma_zone_set_max(V_tcptw_zone, maxtcptw); 166 } 167 return (error); 168 } 169 170 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, maxtcptw, CTLTYPE_INT|CTLFLAG_RW, 171 &maxtcptw, 0, sysctl_maxtcptw, "IU", 172 "Maximum number of compressed TCP TIME_WAIT entries"); 173 174 VNET_DEFINE(int, nolocaltimewait) = 0; 175 #define V_nolocaltimewait VNET(nolocaltimewait) 176 SYSCTL_INT(_net_inet_tcp, OID_AUTO, nolocaltimewait, CTLFLAG_VNET | CTLFLAG_RW, 177 &VNET_NAME(nolocaltimewait), 0, 178 "Do not create compressed TCP TIME_WAIT entries for local connections"); 179 180 void 181 tcp_tw_zone_change(void) 182 { 183 184 if (maxtcptw == 0) 185 uma_zone_set_max(V_tcptw_zone, tcptw_auto_size()); 186 } 187 188 void 189 tcp_tw_init(void) 190 { 191 192 V_tcptw_zone = uma_zcreate("tcptw", sizeof(struct tcptw), 193 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 194 TUNABLE_INT_FETCH("net.inet.tcp.maxtcptw", &maxtcptw); 195 if (maxtcptw == 0) 196 uma_zone_set_max(V_tcptw_zone, tcptw_auto_size()); 197 else 198 uma_zone_set_max(V_tcptw_zone, maxtcptw); 199 TAILQ_INIT(&V_twq_2msl); 200 TW_LOCK_INIT(V_tw_lock, "tcptw"); 201 } 202 203 #ifdef VIMAGE 204 void 205 tcp_tw_destroy(void) 206 { 207 struct tcptw *tw; 208 209 INP_INFO_RLOCK(&V_tcbinfo); 210 while ((tw = TAILQ_FIRST(&V_twq_2msl)) != NULL) 211 tcp_twclose(tw, 0); 212 INP_INFO_RUNLOCK(&V_tcbinfo); 213 214 TW_LOCK_DESTROY(V_tw_lock); 215 uma_zdestroy(V_tcptw_zone); 216 } 217 #endif 218 219 /* 220 * Move a TCP connection into TIME_WAIT state. 221 * tcbinfo is locked. 222 * inp is locked, and is unlocked before returning. 223 */ 224 void 225 tcp_twstart(struct tcpcb *tp) 226 { 227 struct tcptw *tw; 228 struct inpcb *inp = tp->t_inpcb; 229 int acknow; 230 struct socket *so; 231 uint32_t recwin; 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 so = inp->inp_socket; 299 recwin = lmin(lmax(sbspace(&so->so_rcv), 0), 300 (long)TCP_MAXWIN << tp->rcv_scale); 301 if (recwin < (so->so_rcv.sb_hiwat / 4) && 302 recwin < tp->t_maxseg) 303 recwin = 0; 304 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt) && 305 recwin < (tp->rcv_adv - tp->rcv_nxt)) 306 recwin = (tp->rcv_adv - tp->rcv_nxt); 307 tw->last_win = (u_short)(recwin >> tp->rcv_scale); 308 309 /* 310 * Set t_recent if timestamps are used on the connection. 311 */ 312 if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) == 313 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) { 314 tw->t_recent = tp->ts_recent; 315 tw->ts_offset = tp->ts_offset; 316 } else { 317 tw->t_recent = 0; 318 tw->ts_offset = 0; 319 } 320 321 tw->snd_nxt = tp->snd_nxt; 322 tw->rcv_nxt = tp->rcv_nxt; 323 tw->iss = tp->iss; 324 tw->irs = tp->irs; 325 tw->t_starttime = tp->t_starttime; 326 tw->tw_time = 0; 327 328 /* XXX 329 * If this code will 330 * be used for fin-wait-2 state also, then we may need 331 * a ts_recent from the last segment. 332 */ 333 acknow = tp->t_flags & TF_ACKNOW; 334 335 /* 336 * First, discard tcpcb state, which includes stopping its timers and 337 * freeing it. tcp_discardcb() used to also release the inpcb, but 338 * that work is now done in the caller. 339 * 340 * Note: soisdisconnected() call used to be made in tcp_discardcb(), 341 * and might not be needed here any longer. 342 */ 343 tcp_discardcb(tp); 344 soisdisconnected(so); 345 tw->tw_cred = crhold(so->so_cred); 346 SOCK_LOCK(so); 347 tw->tw_so_options = so->so_options; 348 SOCK_UNLOCK(so); 349 if (acknow) 350 tcp_twrespond(tw, TH_ACK); 351 inp->inp_ppcb = tw; 352 inp->inp_flags |= INP_TIMEWAIT; 353 TCPSTATES_INC(TCPS_TIME_WAIT); 354 tcp_tw_2msl_reset(tw, 0); 355 356 /* 357 * If the inpcb owns the sole reference to the socket, then we can 358 * detach and free the socket as it is not needed in time wait. 359 */ 360 if (inp->inp_flags & INP_SOCKREF) { 361 KASSERT(so->so_state & SS_PROTOREF, 362 ("tcp_twstart: !SS_PROTOREF")); 363 inp->inp_flags &= ~INP_SOCKREF; 364 INP_WUNLOCK(inp); 365 ACCEPT_LOCK(); 366 SOCK_LOCK(so); 367 so->so_state &= ~SS_PROTOREF; 368 sofree(so); 369 } else 370 INP_WUNLOCK(inp); 371 } 372 373 /* 374 * Returns 1 if the TIME_WAIT state was killed and we should start over, 375 * looking for a pcb in the listen state. Returns 0 otherwise. 376 * It be called with to == NULL only for pure SYN-segments. 377 */ 378 int 379 tcp_twcheck(struct inpcb *inp, struct tcpopt *to, struct tcphdr *th, 380 struct mbuf *m, int tlen) 381 { 382 struct tcptw *tw; 383 int thflags; 384 tcp_seq seq; 385 386 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 387 INP_WLOCK_ASSERT(inp); 388 389 /* 390 * XXXRW: Time wait state for inpcb has been recycled, but inpcb is 391 * still present. This is undesirable, but temporarily necessary 392 * until we work out how to handle inpcb's who's timewait state has 393 * been removed. 394 */ 395 tw = intotw(inp); 396 if (tw == NULL) 397 goto drop; 398 399 thflags = th->th_flags; 400 KASSERT(to != NULL || (thflags & (TH_SYN | TH_ACK)) == TH_SYN, 401 ("tcp_twcheck: called without options on a non-SYN segment")); 402 403 /* 404 * NOTE: for FIN_WAIT_2 (to be added later), 405 * must validate sequence number before accepting RST 406 */ 407 408 /* 409 * If the segment contains RST: 410 * Drop the segment - see Stevens, vol. 2, p. 964 and 411 * RFC 1337. 412 */ 413 if (thflags & TH_RST) 414 goto drop; 415 416 #if 0 417 /* PAWS not needed at the moment */ 418 /* 419 * RFC 1323 PAWS: If we have a timestamp reply on this segment 420 * and it's less than ts_recent, drop it. 421 */ 422 if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent && 423 TSTMP_LT(to.to_tsval, tp->ts_recent)) { 424 if ((thflags & TH_ACK) == 0) 425 goto drop; 426 goto ack; 427 } 428 /* 429 * ts_recent is never updated because we never accept new segments. 430 */ 431 #endif 432 433 /* 434 * If a new connection request is received 435 * while in TIME_WAIT, drop the old connection 436 * and start over if the sequence numbers 437 * are above the previous ones. 438 */ 439 if ((thflags & TH_SYN) && SEQ_GT(th->th_seq, tw->rcv_nxt)) { 440 tcp_twclose(tw, 0); 441 return (1); 442 } 443 444 /* 445 * Drop the segment if it does not contain an ACK. 446 */ 447 if ((thflags & TH_ACK) == 0) 448 goto drop; 449 450 /* 451 * If timestamps were negotiated during SYN/ACK and a 452 * segment without a timestamp is received, silently drop 453 * the segment. 454 * See section 3.2 of RFC 7323. 455 */ 456 if (((to->to_flags & TOF_TS) == 0) && (tw->t_recent != 0)) { 457 goto drop; 458 } 459 460 /* 461 * Reset the 2MSL timer if this is a duplicate FIN. 462 */ 463 if (thflags & TH_FIN) { 464 seq = th->th_seq + tlen + (thflags & TH_SYN ? 1 : 0); 465 if (seq + 1 == tw->rcv_nxt) 466 tcp_tw_2msl_reset(tw, 1); 467 } 468 469 /* 470 * Acknowledge the segment if it has data or is not a duplicate ACK. 471 */ 472 if (thflags != TH_ACK || tlen != 0 || 473 th->th_seq != tw->rcv_nxt || th->th_ack != tw->snd_nxt) { 474 TCP_PROBE5(receive, NULL, NULL, m, NULL, th); 475 tcp_twrespond(tw, TH_ACK); 476 goto dropnoprobe; 477 } 478 drop: 479 TCP_PROBE5(receive, NULL, NULL, m, NULL, th); 480 dropnoprobe: 481 INP_WUNLOCK(inp); 482 m_freem(m); 483 return (0); 484 } 485 486 void 487 tcp_twclose(struct tcptw *tw, int reuse) 488 { 489 struct socket *so; 490 struct inpcb *inp; 491 492 /* 493 * At this point, we are in one of two situations: 494 * 495 * (1) We have no socket, just an inpcb<->twtcp pair. We can free 496 * all state. 497 * 498 * (2) We have a socket -- if we own a reference, release it and 499 * notify the socket layer. 500 */ 501 inp = tw->tw_inpcb; 502 KASSERT((inp->inp_flags & INP_TIMEWAIT), ("tcp_twclose: !timewait")); 503 KASSERT(intotw(inp) == tw, ("tcp_twclose: inp_ppcb != tw")); 504 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); /* in_pcbfree() */ 505 INP_WLOCK_ASSERT(inp); 506 507 tcp_tw_2msl_stop(tw, reuse); 508 inp->inp_ppcb = NULL; 509 in_pcbdrop(inp); 510 511 so = inp->inp_socket; 512 if (so != NULL) { 513 /* 514 * If there's a socket, handle two cases: first, we own a 515 * strong reference, which we will now release, or we don't 516 * in which case another reference exists (XXXRW: think 517 * about this more), and we don't need to take action. 518 */ 519 if (inp->inp_flags & INP_SOCKREF) { 520 inp->inp_flags &= ~INP_SOCKREF; 521 INP_WUNLOCK(inp); 522 ACCEPT_LOCK(); 523 SOCK_LOCK(so); 524 KASSERT(so->so_state & SS_PROTOREF, 525 ("tcp_twclose: INP_SOCKREF && !SS_PROTOREF")); 526 so->so_state &= ~SS_PROTOREF; 527 sofree(so); 528 } else { 529 /* 530 * If we don't own the only reference, the socket and 531 * inpcb need to be left around to be handled by 532 * tcp_usr_detach() later. 533 */ 534 INP_WUNLOCK(inp); 535 } 536 } else { 537 /* 538 * The socket has been already cleaned-up for us, only free the 539 * inpcb. 540 */ 541 in_pcbfree(inp); 542 } 543 TCPSTAT_INC(tcps_closed); 544 } 545 546 static int 547 tcp_twrespond(struct tcptw *tw, int flags) 548 { 549 struct inpcb *inp = tw->tw_inpcb; 550 #if defined(INET6) || defined(INET) 551 struct tcphdr *th = NULL; 552 #endif 553 struct mbuf *m; 554 #ifdef INET 555 struct ip *ip = NULL; 556 #endif 557 u_int hdrlen, optlen; 558 int error = 0; /* Keep compiler happy */ 559 struct tcpopt to; 560 #ifdef INET6 561 struct ip6_hdr *ip6 = NULL; 562 int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6; 563 #endif 564 hdrlen = 0; /* Keep compiler happy */ 565 566 INP_WLOCK_ASSERT(inp); 567 568 m = m_gethdr(M_NOWAIT, MT_DATA); 569 if (m == NULL) 570 return (ENOBUFS); 571 m->m_data += max_linkhdr; 572 573 #ifdef MAC 574 mac_inpcb_create_mbuf(inp, m); 575 #endif 576 577 #ifdef INET6 578 if (isipv6) { 579 hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 580 ip6 = mtod(m, struct ip6_hdr *); 581 th = (struct tcphdr *)(ip6 + 1); 582 tcpip_fillheaders(inp, ip6, th); 583 } 584 #endif 585 #if defined(INET6) && defined(INET) 586 else 587 #endif 588 #ifdef INET 589 { 590 hdrlen = sizeof(struct tcpiphdr); 591 ip = mtod(m, struct ip *); 592 th = (struct tcphdr *)(ip + 1); 593 tcpip_fillheaders(inp, ip, th); 594 } 595 #endif 596 to.to_flags = 0; 597 598 /* 599 * Send a timestamp and echo-reply if both our side and our peer 600 * have sent timestamps in our SYN's and this is not a RST. 601 */ 602 if (tw->t_recent && flags == TH_ACK) { 603 to.to_flags |= TOF_TS; 604 to.to_tsval = tcp_ts_getticks() + tw->ts_offset; 605 to.to_tsecr = tw->t_recent; 606 } 607 optlen = tcp_addoptions(&to, (u_char *)(th + 1)); 608 609 m->m_len = hdrlen + optlen; 610 m->m_pkthdr.len = m->m_len; 611 612 KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small")); 613 614 th->th_seq = htonl(tw->snd_nxt); 615 th->th_ack = htonl(tw->rcv_nxt); 616 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 617 th->th_flags = flags; 618 th->th_win = htons(tw->last_win); 619 620 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 621 #ifdef INET6 622 if (isipv6) { 623 m->m_pkthdr.csum_flags = CSUM_TCP_IPV6; 624 th->th_sum = in6_cksum_pseudo(ip6, 625 sizeof(struct tcphdr) + optlen, IPPROTO_TCP, 0); 626 ip6->ip6_hlim = in6_selecthlim(inp, NULL); 627 TCP_PROBE5(send, NULL, NULL, ip6, NULL, th); 628 error = ip6_output(m, inp->in6p_outputopts, NULL, 629 (tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp); 630 } 631 #endif 632 #if defined(INET6) && defined(INET) 633 else 634 #endif 635 #ifdef INET 636 { 637 m->m_pkthdr.csum_flags = CSUM_TCP; 638 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 639 htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP)); 640 ip->ip_len = htons(m->m_pkthdr.len); 641 if (V_path_mtu_discovery) 642 ip->ip_off |= htons(IP_DF); 643 TCP_PROBE5(send, NULL, NULL, ip, NULL, th); 644 error = ip_output(m, inp->inp_options, NULL, 645 ((tw->tw_so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0), 646 NULL, inp); 647 } 648 #endif 649 if (flags & TH_ACK) 650 TCPSTAT_INC(tcps_sndacks); 651 else 652 TCPSTAT_INC(tcps_sndctrl); 653 TCPSTAT_INC(tcps_sndtotal); 654 return (error); 655 } 656 657 static void 658 tcp_tw_2msl_reset(struct tcptw *tw, int rearm) 659 { 660 661 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 662 INP_WLOCK_ASSERT(tw->tw_inpcb); 663 664 TW_WLOCK(V_tw_lock); 665 if (rearm) 666 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl); 667 tw->tw_time = ticks + 2 * tcp_msl; 668 TAILQ_INSERT_TAIL(&V_twq_2msl, tw, tw_2msl); 669 TW_WUNLOCK(V_tw_lock); 670 } 671 672 static void 673 tcp_tw_2msl_stop(struct tcptw *tw, int reuse) 674 { 675 struct ucred *cred; 676 struct inpcb *inp; 677 int released; 678 679 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 680 681 TW_WLOCK(V_tw_lock); 682 inp = tw->tw_inpcb; 683 tw->tw_inpcb = NULL; 684 685 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl); 686 cred = tw->tw_cred; 687 tw->tw_cred = NULL; 688 TW_WUNLOCK(V_tw_lock); 689 690 if (cred != NULL) 691 crfree(cred); 692 693 released = in_pcbrele_wlocked(inp); 694 KASSERT(!released, ("%s: inp should not be released here", __func__)); 695 696 if (!reuse) 697 uma_zfree(V_tcptw_zone, tw); 698 TCPSTATES_DEC(TCPS_TIME_WAIT); 699 } 700 701 struct tcptw * 702 tcp_tw_2msl_scan(int reuse) 703 { 704 struct tcptw *tw; 705 struct inpcb *inp; 706 707 #ifdef INVARIANTS 708 if (reuse) { 709 /* 710 * Exclusive pcbinfo lock is not required in reuse case even if 711 * two inpcb locks can be acquired simultaneously: 712 * - the inpcb transitioning to TIME_WAIT state in 713 * tcp_tw_start(), 714 * - the inpcb closed by tcp_twclose(). 715 * 716 * It is because only inpcbs in FIN_WAIT2 or CLOSING states can 717 * transition in TIME_WAIT state. Then a pcbcb cannot be in 718 * TIME_WAIT list and transitioning to TIME_WAIT state at same 719 * time. 720 */ 721 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 722 } 723 #endif 724 725 for (;;) { 726 TW_RLOCK(V_tw_lock); 727 tw = TAILQ_FIRST(&V_twq_2msl); 728 if (tw == NULL || (!reuse && (tw->tw_time - ticks) > 0)) { 729 TW_RUNLOCK(V_tw_lock); 730 break; 731 } 732 KASSERT(tw->tw_inpcb != NULL, ("%s: tw->tw_inpcb == NULL", 733 __func__)); 734 735 inp = tw->tw_inpcb; 736 in_pcbref(inp); 737 TW_RUNLOCK(V_tw_lock); 738 739 if (INP_INFO_TRY_RLOCK(&V_tcbinfo)) { 740 741 INP_WLOCK(inp); 742 tw = intotw(inp); 743 if (in_pcbrele_wlocked(inp)) { 744 if (__predict_true(tw == NULL)) { 745 INP_INFO_RUNLOCK(&V_tcbinfo); 746 continue; 747 } else { 748 /* This should not happen as in TIMEWAIT 749 * state the inp should not be destroyed 750 * before its tcptw. If INVARIANTS is 751 * defined panic. 752 */ 753 #ifdef INVARIANTS 754 panic("%s: Panic before an infinite " 755 "loop: INP_TIMEWAIT && (INP_FREED " 756 "|| inp last reference) && tw != " 757 "NULL", __func__); 758 #else 759 log(LOG_ERR, "%s: Avoid an infinite " 760 "loop: INP_TIMEWAIT && (INP_FREED " 761 "|| inp last reference) && tw != " 762 "NULL", __func__); 763 #endif 764 INP_INFO_RUNLOCK(&V_tcbinfo); 765 break; 766 } 767 } 768 769 if (tw == NULL) { 770 /* tcp_twclose() has already been called */ 771 INP_WUNLOCK(inp); 772 INP_INFO_RUNLOCK(&V_tcbinfo); 773 continue; 774 } 775 776 tcp_twclose(tw, reuse); 777 INP_INFO_RUNLOCK(&V_tcbinfo); 778 if (reuse) 779 return tw; 780 } else { 781 /* INP_INFO lock is busy, continue later. */ 782 INP_WLOCK(inp); 783 if (!in_pcbrele_wlocked(inp)) 784 INP_WUNLOCK(inp); 785 break; 786 } 787 } 788 789 return NULL; 790 }
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