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_kdtrace.h> 67 #include <netinet/in_pcb.h> 68 #include <netinet/in_systm.h> 69 #include <netinet/in_var.h> 70 #include <netinet/ip.h> 71 #include <netinet/ip_icmp.h> 72 #include <netinet/ip_var.h> 73 #ifdef INET6 74 #include <netinet/ip6.h> 75 #include <netinet6/in6_pcb.h> 76 #include <netinet6/ip6_var.h> 77 #include <netinet6/scope6_var.h> 78 #include <netinet6/nd6.h> 79 #endif 80 #include <netinet/tcp.h> 81 #include <netinet/tcp_fsm.h> 82 #include <netinet/tcp_seq.h> 83 #include <netinet/tcp_timer.h> 84 #include <netinet/tcp_var.h> 85 #ifdef INET6 86 #include <netinet6/tcp6_var.h> 87 #endif 88 #include <netinet/tcpip.h> 89 #ifdef TCPDEBUG 90 #include <netinet/tcp_debug.h> 91 #endif 92 #ifdef INET6 93 #include <netinet6/ip6protosw.h> 94 #endif 95 96 #include <netinet/udp.h> 97 #include <netinet/udp_var.h> 98 #include <machine/in_cksum.h> 99 100 #include <security/mac/mac_framework.h> 101 102 VNET_DEFINE_STATIC(uma_zone_t, tcptw_zone); 103 #define V_tcptw_zone VNET(tcptw_zone) 104 static int maxtcptw; 105 106 /* 107 * The timed wait queue contains references to each of the TCP sessions 108 * currently in the TIME_WAIT state. The queue pointers, including the 109 * queue pointers in each tcptw structure, are protected using the global 110 * timewait lock, which must be held over queue iteration and modification. 111 * 112 * Rules on tcptw usage: 113 * - a inpcb is always freed _after_ its tcptw 114 * - a tcptw relies on its inpcb reference counting for memory stability 115 * - a tcptw is dereferenceable only while its inpcb is locked 116 */ 117 VNET_DEFINE_STATIC(TAILQ_HEAD(, tcptw), twq_2msl); 118 #define V_twq_2msl VNET(twq_2msl) 119 120 /* Global timewait lock */ 121 VNET_DEFINE_STATIC(struct rwlock, tw_lock); 122 #define V_tw_lock VNET(tw_lock) 123 124 #define TW_LOCK_INIT(tw, d) rw_init_flags(&(tw), (d), 0) 125 #define TW_LOCK_DESTROY(tw) rw_destroy(&(tw)) 126 #define TW_RLOCK(tw) rw_rlock(&(tw)) 127 #define TW_WLOCK(tw) rw_wlock(&(tw)) 128 #define TW_RUNLOCK(tw) rw_runlock(&(tw)) 129 #define TW_WUNLOCK(tw) rw_wunlock(&(tw)) 130 #define TW_LOCK_ASSERT(tw) rw_assert(&(tw), RA_LOCKED) 131 #define TW_RLOCK_ASSERT(tw) rw_assert(&(tw), RA_RLOCKED) 132 #define TW_WLOCK_ASSERT(tw) rw_assert(&(tw), RA_WLOCKED) 133 #define TW_UNLOCK_ASSERT(tw) rw_assert(&(tw), RA_UNLOCKED) 134 135 static void tcp_tw_2msl_reset(struct tcptw *, int); 136 static void tcp_tw_2msl_stop(struct tcptw *, int); 137 static int tcp_twrespond(struct tcptw *, int); 138 139 static int 140 tcptw_auto_size(void) 141 { 142 int halfrange; 143 144 /* 145 * Max out at half the ephemeral port range so that TIME_WAIT 146 * sockets don't tie up too many ephemeral ports. 147 */ 148 if (V_ipport_lastauto > V_ipport_firstauto) 149 halfrange = (V_ipport_lastauto - V_ipport_firstauto) / 2; 150 else 151 halfrange = (V_ipport_firstauto - V_ipport_lastauto) / 2; 152 /* Protect against goofy port ranges smaller than 32. */ 153 return (imin(imax(halfrange, 32), maxsockets / 5)); 154 } 155 156 static int 157 sysctl_maxtcptw(SYSCTL_HANDLER_ARGS) 158 { 159 int error, new; 160 161 if (maxtcptw == 0) 162 new = tcptw_auto_size(); 163 else 164 new = maxtcptw; 165 error = sysctl_handle_int(oidp, &new, 0, req); 166 if (error == 0 && req->newptr) 167 if (new >= 32) { 168 maxtcptw = new; 169 uma_zone_set_max(V_tcptw_zone, maxtcptw); 170 } 171 return (error); 172 } 173 174 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, maxtcptw, 175 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 176 &maxtcptw, 0, sysctl_maxtcptw, "IU", 177 "Maximum number of compressed TCP TIME_WAIT entries"); 178 179 VNET_DEFINE_STATIC(int, nolocaltimewait) = 0; 180 #define V_nolocaltimewait VNET(nolocaltimewait) 181 SYSCTL_INT(_net_inet_tcp, OID_AUTO, nolocaltimewait, CTLFLAG_VNET | CTLFLAG_RW, 182 &VNET_NAME(nolocaltimewait), 0, 183 "Do not create compressed TCP TIME_WAIT entries for local connections"); 184 185 void 186 tcp_tw_zone_change(void) 187 { 188 189 if (maxtcptw == 0) 190 uma_zone_set_max(V_tcptw_zone, tcptw_auto_size()); 191 } 192 193 void 194 tcp_tw_init(void) 195 { 196 197 V_tcptw_zone = uma_zcreate("tcptw", sizeof(struct tcptw), 198 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 199 TUNABLE_INT_FETCH("net.inet.tcp.maxtcptw", &maxtcptw); 200 if (maxtcptw == 0) 201 uma_zone_set_max(V_tcptw_zone, tcptw_auto_size()); 202 else 203 uma_zone_set_max(V_tcptw_zone, maxtcptw); 204 TAILQ_INIT(&V_twq_2msl); 205 TW_LOCK_INIT(V_tw_lock, "tcptw"); 206 } 207 208 #ifdef VIMAGE 209 void 210 tcp_tw_destroy(void) 211 { 212 struct tcptw *tw; 213 struct epoch_tracker et; 214 215 NET_EPOCH_ENTER(et); 216 while ((tw = TAILQ_FIRST(&V_twq_2msl)) != NULL) 217 tcp_twclose(tw, 0); 218 NET_EPOCH_EXIT(et); 219 220 TW_LOCK_DESTROY(V_tw_lock); 221 uma_zdestroy(V_tcptw_zone); 222 } 223 #endif 224 225 /* 226 * Move a TCP connection into TIME_WAIT state. 227 * tcbinfo is locked. 228 * inp is locked, and is unlocked before returning. 229 */ 230 void 231 tcp_twstart(struct tcpcb *tp) 232 { 233 struct tcptw twlocal, *tw; 234 struct inpcb *inp = tp->t_inpcb; 235 struct socket *so; 236 uint32_t recwin; 237 bool acknow, local; 238 #ifdef INET6 239 bool isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6; 240 #endif 241 242 NET_EPOCH_ASSERT(); 243 INP_WLOCK_ASSERT(inp); 244 245 /* A dropped inp should never transition to TIME_WAIT state. */ 246 KASSERT((inp->inp_flags & INP_DROPPED) == 0, ("tcp_twstart: " 247 "(inp->inp_flags & INP_DROPPED) != 0")); 248 249 if (V_nolocaltimewait) { 250 #ifdef INET6 251 if (isipv6) 252 local = in6_localaddr(&inp->in6p_faddr); 253 else 254 #endif 255 #ifdef INET 256 local = in_localip(inp->inp_faddr); 257 #else 258 local = false; 259 #endif 260 } else 261 local = false; 262 263 /* 264 * For use only by DTrace. We do not reference the state 265 * after this point so modifying it in place is not a problem. 266 */ 267 tcp_state_change(tp, TCPS_TIME_WAIT); 268 269 if (local) 270 tw = &twlocal; 271 else 272 tw = uma_zalloc(V_tcptw_zone, M_NOWAIT); 273 if (tw == NULL) { 274 /* 275 * Reached limit on total number of TIMEWAIT connections 276 * allowed. Remove a connection from TIMEWAIT queue in LRU 277 * fashion to make room for this connection. 278 * 279 * XXX: Check if it possible to always have enough room 280 * in advance based on guarantees provided by uma_zalloc(). 281 */ 282 tw = tcp_tw_2msl_scan(1); 283 if (tw == NULL) { 284 tp = tcp_close(tp); 285 if (tp != NULL) 286 INP_WUNLOCK(inp); 287 return; 288 } 289 } 290 /* 291 * For !local case the tcptw will hold a reference on its inpcb 292 * until tcp_twclose is called. 293 */ 294 tw->tw_inpcb = inp; 295 296 /* 297 * Recover last window size sent. 298 */ 299 so = inp->inp_socket; 300 recwin = lmin(lmax(sbspace(&so->so_rcv), 0), 301 (long)TCP_MAXWIN << tp->rcv_scale); 302 if (recwin < (so->so_rcv.sb_hiwat / 4) && 303 recwin < tp->t_maxseg) 304 recwin = 0; 305 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt) && 306 recwin < (tp->rcv_adv - tp->rcv_nxt)) 307 recwin = (tp->rcv_adv - tp->rcv_nxt); 308 tw->last_win = (u_short)(recwin >> tp->rcv_scale); 309 310 /* 311 * Set t_recent if timestamps are used on the connection. 312 */ 313 if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) == 314 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) { 315 tw->t_recent = tp->ts_recent; 316 tw->ts_offset = tp->ts_offset; 317 } else { 318 tw->t_recent = 0; 319 tw->ts_offset = 0; 320 } 321 322 tw->snd_nxt = tp->snd_nxt; 323 tw->t_port = tp->t_port; 324 tw->rcv_nxt = tp->rcv_nxt; 325 tw->iss = tp->iss; 326 tw->irs = tp->irs; 327 tw->t_starttime = tp->t_starttime; 328 tw->tw_time = 0; 329 330 /* XXX 331 * If this code will 332 * be used for fin-wait-2 state also, then we may need 333 * a ts_recent from the last segment. 334 */ 335 acknow = tp->t_flags & TF_ACKNOW; 336 337 /* 338 * First, discard tcpcb state, which includes stopping its timers and 339 * freeing it. tcp_discardcb() used to also release the inpcb, but 340 * that work is now done in the caller. 341 * 342 * Note: soisdisconnected() call used to be made in tcp_discardcb(), 343 * and might not be needed here any longer. 344 */ 345 tcp_discardcb(tp); 346 soisdisconnected(so); 347 tw->tw_so_options = so->so_options; 348 inp->inp_flags |= INP_TIMEWAIT; 349 if (acknow) 350 tcp_twrespond(tw, TH_ACK); 351 if (local) 352 in_pcbdrop(inp); 353 else { 354 in_pcbref(inp); /* Reference from tw */ 355 tw->tw_cred = crhold(so->so_cred); 356 inp->inp_ppcb = tw; 357 TCPSTATES_INC(TCPS_TIME_WAIT); 358 tcp_tw_2msl_reset(tw, 0); 359 } 360 361 /* 362 * If the inpcb owns the sole reference to the socket, then we can 363 * detach and free the socket as it is not needed in time wait. 364 */ 365 if (inp->inp_flags & INP_SOCKREF) { 366 KASSERT(so->so_state & SS_PROTOREF, 367 ("tcp_twstart: !SS_PROTOREF")); 368 inp->inp_flags &= ~INP_SOCKREF; 369 INP_WUNLOCK(inp); 370 SOCK_LOCK(so); 371 so->so_state &= ~SS_PROTOREF; 372 sofree(so); 373 } else 374 INP_WUNLOCK(inp); 375 } 376 377 /* 378 * Returns 1 if the TIME_WAIT state was killed and we should start over, 379 * looking for a pcb in the listen state. Returns 0 otherwise. 380 * 381 * For pure SYN-segments the PCB shall be read-locked and the tcpopt pointer 382 * may be NULL. For the rest write-lock and valid tcpopt. 383 */ 384 int 385 tcp_twcheck(struct inpcb *inp, struct tcpopt *to, struct tcphdr *th, 386 struct mbuf *m, int tlen) 387 { 388 struct tcptw *tw; 389 int thflags; 390 tcp_seq seq; 391 392 NET_EPOCH_ASSERT(); 393 INP_LOCK_ASSERT(inp); 394 395 /* 396 * XXXRW: Time wait state for inpcb has been recycled, but inpcb is 397 * still present. This is undesirable, but temporarily necessary 398 * until we work out how to handle inpcb's who's timewait state has 399 * been removed. 400 */ 401 tw = intotw(inp); 402 if (tw == NULL) 403 goto drop; 404 405 thflags = th->th_flags; 406 #ifdef INVARIANTS 407 if ((thflags & (TH_SYN | TH_ACK)) == TH_SYN) 408 INP_RLOCK_ASSERT(inp); 409 else { 410 INP_WLOCK_ASSERT(inp); 411 KASSERT(to != NULL, 412 ("%s: called without options on a non-SYN segment", 413 __func__)); 414 } 415 #endif 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 * Allow UDP port number changes in this case. 453 */ 454 if ((thflags & TH_SYN) && SEQ_GT(th->th_seq, tw->rcv_nxt)) { 455 /* 456 * In case we can't upgrade our lock just pretend we have 457 * lost this packet. 458 */ 459 if (((thflags & (TH_SYN | TH_ACK)) == TH_SYN) && 460 INP_TRY_UPGRADE(inp) == 0) 461 goto drop; 462 tcp_twclose(tw, 0); 463 return (1); 464 } 465 466 /* 467 * Send RST if UDP port numbers don't match 468 */ 469 if (tw->t_port != m->m_pkthdr.tcp_tun_port) { 470 if (th->th_flags & TH_ACK) { 471 tcp_respond(NULL, mtod(m, void *), th, m, 472 (tcp_seq)0, th->th_ack, TH_RST); 473 } else { 474 if (th->th_flags & TH_SYN) 475 tlen++; 476 if (th->th_flags & TH_FIN) 477 tlen++; 478 tcp_respond(NULL, mtod(m, void *), th, m, 479 th->th_seq+tlen, (tcp_seq)0, TH_RST|TH_ACK); 480 } 481 INP_UNLOCK(inp); 482 return (0); 483 } 484 485 /* 486 * Drop the segment if it does not contain an ACK. 487 */ 488 if ((thflags & TH_ACK) == 0) 489 goto drop; 490 491 INP_WLOCK_ASSERT(inp); 492 493 /* 494 * If timestamps were negotiated during SYN/ACK and a 495 * segment without a timestamp is received, silently drop 496 * the segment, unless the missing timestamps are tolerated. 497 * See section 3.2 of RFC 7323. 498 */ 499 if (((to->to_flags & TOF_TS) == 0) && (tw->t_recent != 0) && 500 (V_tcp_tolerate_missing_ts == 0)) { 501 goto drop; 502 } 503 504 /* 505 * Reset the 2MSL timer if this is a duplicate FIN. 506 */ 507 if (thflags & TH_FIN) { 508 seq = th->th_seq + tlen + (thflags & TH_SYN ? 1 : 0); 509 if (seq + 1 == tw->rcv_nxt) 510 tcp_tw_2msl_reset(tw, 1); 511 } 512 513 /* 514 * Acknowledge the segment if it has data or is not a duplicate ACK. 515 */ 516 if (thflags != TH_ACK || tlen != 0 || 517 th->th_seq != tw->rcv_nxt || th->th_ack != tw->snd_nxt) { 518 TCP_PROBE5(receive, NULL, NULL, m, NULL, th); 519 tcp_twrespond(tw, TH_ACK); 520 goto dropnoprobe; 521 } 522 drop: 523 TCP_PROBE5(receive, NULL, NULL, m, NULL, th); 524 dropnoprobe: 525 INP_UNLOCK(inp); 526 m_freem(m); 527 return (0); 528 } 529 530 void 531 tcp_twclose(struct tcptw *tw, int reuse) 532 { 533 struct socket *so; 534 struct inpcb *inp; 535 536 /* 537 * At this point, we are in one of two situations: 538 * 539 * (1) We have no socket, just an inpcb<->twtcp pair. We can free 540 * all state. 541 * 542 * (2) We have a socket -- if we own a reference, release it and 543 * notify the socket layer. 544 */ 545 inp = tw->tw_inpcb; 546 KASSERT((inp->inp_flags & INP_TIMEWAIT), ("tcp_twclose: !timewait")); 547 KASSERT(intotw(inp) == tw, ("tcp_twclose: inp_ppcb != tw")); 548 NET_EPOCH_ASSERT(); 549 INP_WLOCK_ASSERT(inp); 550 551 tcp_tw_2msl_stop(tw, reuse); 552 inp->inp_ppcb = NULL; 553 in_pcbdrop(inp); 554 555 so = inp->inp_socket; 556 if (so != NULL) { 557 /* 558 * If there's a socket, handle two cases: first, we own a 559 * strong reference, which we will now release, or we don't 560 * in which case another reference exists (XXXRW: think 561 * about this more), and we don't need to take action. 562 */ 563 if (inp->inp_flags & INP_SOCKREF) { 564 inp->inp_flags &= ~INP_SOCKREF; 565 INP_WUNLOCK(inp); 566 SOCK_LOCK(so); 567 KASSERT(so->so_state & SS_PROTOREF, 568 ("tcp_twclose: INP_SOCKREF && !SS_PROTOREF")); 569 so->so_state &= ~SS_PROTOREF; 570 sofree(so); 571 } else { 572 /* 573 * If we don't own the only reference, the socket and 574 * inpcb need to be left around to be handled by 575 * tcp_usr_detach() later. 576 */ 577 INP_WUNLOCK(inp); 578 } 579 } else { 580 /* 581 * The socket has been already cleaned-up for us, only free the 582 * inpcb. 583 */ 584 in_pcbfree(inp); 585 } 586 TCPSTAT_INC(tcps_closed); 587 } 588 589 static int 590 tcp_twrespond(struct tcptw *tw, int flags) 591 { 592 struct inpcb *inp = tw->tw_inpcb; 593 #if defined(INET6) || defined(INET) 594 struct tcphdr *th = NULL; 595 #endif 596 struct mbuf *m; 597 #ifdef INET 598 struct ip *ip = NULL; 599 #endif 600 u_int hdrlen, optlen, ulen; 601 int error = 0; /* Keep compiler happy */ 602 struct tcpopt to; 603 #ifdef INET6 604 struct ip6_hdr *ip6 = NULL; 605 int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6; 606 #endif 607 struct udphdr *udp = NULL; 608 hdrlen = 0; /* Keep compiler happy */ 609 610 INP_WLOCK_ASSERT(inp); 611 612 m = m_gethdr(M_NOWAIT, MT_DATA); 613 if (m == NULL) 614 return (ENOBUFS); 615 m->m_data += max_linkhdr; 616 617 #ifdef MAC 618 mac_inpcb_create_mbuf(inp, m); 619 #endif 620 621 #ifdef INET6 622 if (isipv6) { 623 hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 624 ip6 = mtod(m, struct ip6_hdr *); 625 if (tw->t_port) { 626 udp = (struct udphdr *)(ip6 + 1); 627 hdrlen += sizeof(struct udphdr); 628 udp->uh_sport = htons(V_tcp_udp_tunneling_port); 629 udp->uh_dport = tw->t_port; 630 ulen = (hdrlen - sizeof(struct ip6_hdr)); 631 th = (struct tcphdr *)(udp + 1); 632 } else 633 th = (struct tcphdr *)(ip6 + 1); 634 tcpip_fillheaders(inp, tw->t_port, ip6, th); 635 } 636 #endif 637 #if defined(INET6) && defined(INET) 638 else 639 #endif 640 #ifdef INET 641 { 642 hdrlen = sizeof(struct tcpiphdr); 643 ip = mtod(m, struct ip *); 644 if (tw->t_port) { 645 udp = (struct udphdr *)(ip + 1); 646 hdrlen += sizeof(struct udphdr); 647 udp->uh_sport = htons(V_tcp_udp_tunneling_port); 648 udp->uh_dport = tw->t_port; 649 ulen = (hdrlen - sizeof(struct ip)); 650 th = (struct tcphdr *)(udp + 1); 651 } else 652 th = (struct tcphdr *)(ip + 1); 653 tcpip_fillheaders(inp, tw->t_port, ip, th); 654 } 655 #endif 656 to.to_flags = 0; 657 658 /* 659 * Send a timestamp and echo-reply if both our side and our peer 660 * have sent timestamps in our SYN's and this is not a RST. 661 */ 662 if (tw->t_recent && flags == TH_ACK) { 663 to.to_flags |= TOF_TS; 664 to.to_tsval = tcp_ts_getticks() + tw->ts_offset; 665 to.to_tsecr = tw->t_recent; 666 } 667 optlen = tcp_addoptions(&to, (u_char *)(th + 1)); 668 669 if (udp) { 670 ulen += optlen; 671 udp->uh_ulen = htons(ulen); 672 } 673 m->m_len = hdrlen + optlen; 674 m->m_pkthdr.len = m->m_len; 675 676 KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small")); 677 678 th->th_seq = htonl(tw->snd_nxt); 679 th->th_ack = htonl(tw->rcv_nxt); 680 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 681 th->th_flags = flags; 682 th->th_win = htons(tw->last_win); 683 684 #ifdef INET6 685 if (isipv6) { 686 if (tw->t_port) { 687 m->m_pkthdr.csum_flags = CSUM_UDP_IPV6; 688 m->m_pkthdr.csum_data = offsetof(struct udphdr, uh_sum); 689 udp->uh_sum = in6_cksum_pseudo(ip6, ulen, IPPROTO_UDP, 0); 690 th->th_sum = htons(0); 691 } else { 692 m->m_pkthdr.csum_flags = CSUM_TCP_IPV6; 693 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 694 th->th_sum = in6_cksum_pseudo(ip6, 695 sizeof(struct tcphdr) + optlen, IPPROTO_TCP, 0); 696 } 697 ip6->ip6_hlim = in6_selecthlim(inp, NULL); 698 TCP_PROBE5(send, NULL, NULL, ip6, NULL, th); 699 error = ip6_output(m, inp->in6p_outputopts, NULL, 700 (tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp); 701 } 702 #endif 703 #if defined(INET6) && defined(INET) 704 else 705 #endif 706 #ifdef INET 707 { 708 if (tw->t_port) { 709 m->m_pkthdr.csum_flags = CSUM_UDP; 710 m->m_pkthdr.csum_data = offsetof(struct udphdr, uh_sum); 711 udp->uh_sum = in_pseudo(ip->ip_src.s_addr, 712 ip->ip_dst.s_addr, htons(ulen + IPPROTO_UDP)); 713 th->th_sum = htons(0); 714 } else { 715 m->m_pkthdr.csum_flags = CSUM_TCP; 716 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 717 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 718 htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP)); 719 } 720 ip->ip_len = htons(m->m_pkthdr.len); 721 if (V_path_mtu_discovery) 722 ip->ip_off |= htons(IP_DF); 723 TCP_PROBE5(send, NULL, NULL, ip, NULL, th); 724 error = ip_output(m, inp->inp_options, NULL, 725 ((tw->tw_so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0), 726 NULL, inp); 727 } 728 #endif 729 if (flags & TH_ACK) 730 TCPSTAT_INC(tcps_sndacks); 731 else 732 TCPSTAT_INC(tcps_sndctrl); 733 TCPSTAT_INC(tcps_sndtotal); 734 return (error); 735 } 736 737 static void 738 tcp_tw_2msl_reset(struct tcptw *tw, int rearm) 739 { 740 741 NET_EPOCH_ASSERT(); 742 INP_WLOCK_ASSERT(tw->tw_inpcb); 743 744 TW_WLOCK(V_tw_lock); 745 if (rearm) 746 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl); 747 tw->tw_time = ticks + 2 * tcp_msl; 748 TAILQ_INSERT_TAIL(&V_twq_2msl, tw, tw_2msl); 749 TW_WUNLOCK(V_tw_lock); 750 } 751 752 static void 753 tcp_tw_2msl_stop(struct tcptw *tw, int reuse) 754 { 755 struct ucred *cred; 756 struct inpcb *inp; 757 int released __unused; 758 759 NET_EPOCH_ASSERT(); 760 761 TW_WLOCK(V_tw_lock); 762 inp = tw->tw_inpcb; 763 tw->tw_inpcb = NULL; 764 765 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl); 766 cred = tw->tw_cred; 767 tw->tw_cred = NULL; 768 TW_WUNLOCK(V_tw_lock); 769 770 if (cred != NULL) 771 crfree(cred); 772 773 released = in_pcbrele_wlocked(inp); 774 KASSERT(!released, ("%s: inp should not be released here", __func__)); 775 776 if (!reuse) 777 uma_zfree(V_tcptw_zone, tw); 778 TCPSTATES_DEC(TCPS_TIME_WAIT); 779 } 780 781 struct tcptw * 782 tcp_tw_2msl_scan(int reuse) 783 { 784 struct tcptw *tw; 785 struct inpcb *inp; 786 787 NET_EPOCH_ASSERT(); 788 789 for (;;) { 790 TW_RLOCK(V_tw_lock); 791 tw = TAILQ_FIRST(&V_twq_2msl); 792 if (tw == NULL || (!reuse && (tw->tw_time - ticks) > 0)) { 793 TW_RUNLOCK(V_tw_lock); 794 break; 795 } 796 KASSERT(tw->tw_inpcb != NULL, ("%s: tw->tw_inpcb == NULL", 797 __func__)); 798 799 inp = tw->tw_inpcb; 800 in_pcbref(inp); 801 TW_RUNLOCK(V_tw_lock); 802 803 INP_WLOCK(inp); 804 tw = intotw(inp); 805 if (in_pcbrele_wlocked(inp)) { 806 if (__predict_true(tw == NULL)) { 807 continue; 808 } else { 809 /* This should not happen as in TIMEWAIT 810 * state the inp should not be destroyed 811 * before its tcptw. If INVARIANTS is 812 * defined panic. 813 */ 814 #ifdef INVARIANTS 815 panic("%s: Panic before an infinite " 816 "loop: INP_TIMEWAIT && (INP_FREED " 817 "|| inp last reference) && tw != " 818 "NULL", __func__); 819 #else 820 log(LOG_ERR, "%s: Avoid an infinite " 821 "loop: INP_TIMEWAIT && (INP_FREED " 822 "|| inp last reference) && tw != " 823 "NULL", __func__); 824 #endif 825 break; 826 } 827 } 828 829 if (tw == NULL) { 830 /* tcp_twclose() has already been called */ 831 INP_WUNLOCK(inp); 832 continue; 833 } 834 835 tcp_twclose(tw, reuse); 836 if (reuse) 837 return tw; 838 } 839 840 return NULL; 841 } 842