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(bool, nolocaltimewait) = true; 180 #define V_nolocaltimewait VNET(nolocaltimewait) 181 SYSCTL_BOOL(_net_inet_tcp, OID_AUTO, nolocaltimewait, CTLFLAG_VNET | CTLFLAG_RW, 182 &VNET_NAME(nolocaltimewait), true, 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 * If that fails, use on stack tw at least to be able to 279 * run through tcp_twrespond() and standard tcpcb discard 280 * routine. 281 * 282 * XXX: Check if it possible to always have enough room 283 * in advance based on guarantees provided by uma_zalloc(). 284 */ 285 tw = tcp_tw_2msl_scan(1); 286 if (tw == NULL) { 287 tw = &twlocal; 288 local = true; 289 } 290 } 291 /* 292 * For !local case the tcptw will hold a reference on its inpcb 293 * until tcp_twclose is called. 294 */ 295 tw->tw_inpcb = inp; 296 297 /* 298 * Recover last window size sent. 299 */ 300 so = inp->inp_socket; 301 recwin = lmin(lmax(sbspace(&so->so_rcv), 0), 302 (long)TCP_MAXWIN << tp->rcv_scale); 303 if (recwin < (so->so_rcv.sb_hiwat / 4) && 304 recwin < tp->t_maxseg) 305 recwin = 0; 306 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt) && 307 recwin < (tp->rcv_adv - tp->rcv_nxt)) 308 recwin = (tp->rcv_adv - tp->rcv_nxt); 309 tw->last_win = (u_short)(recwin >> tp->rcv_scale); 310 311 /* 312 * Set t_recent if timestamps are used on the connection. 313 */ 314 if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) == 315 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) { 316 tw->t_recent = tp->ts_recent; 317 tw->ts_offset = tp->ts_offset; 318 } else { 319 tw->t_recent = 0; 320 tw->ts_offset = 0; 321 } 322 323 tw->snd_nxt = tp->snd_nxt; 324 tw->t_port = tp->t_port; 325 tw->rcv_nxt = tp->rcv_nxt; 326 tw->iss = tp->iss; 327 tw->irs = tp->irs; 328 tw->t_starttime = tp->t_starttime; 329 tw->tw_time = 0; 330 331 /* XXX 332 * If this code will 333 * be used for fin-wait-2 state also, then we may need 334 * a ts_recent from the last segment. 335 */ 336 acknow = tp->t_flags & TF_ACKNOW; 337 338 /* 339 * First, discard tcpcb state, which includes stopping its timers and 340 * freeing it. tcp_discardcb() used to also release the inpcb, but 341 * that work is now done in the caller. 342 * 343 * Note: soisdisconnected() call used to be made in tcp_discardcb(), 344 * and might not be needed here any longer. 345 */ 346 tcp_discardcb(tp); 347 soisdisconnected(so); 348 tw->tw_so_options = so->so_options; 349 inp->inp_flags |= INP_TIMEWAIT; 350 if (acknow) 351 tcp_twrespond(tw, TH_ACK); 352 if (local) 353 in_pcbdrop(inp); 354 else { 355 in_pcbref(inp); /* Reference from tw */ 356 tw->tw_cred = crhold(so->so_cred); 357 inp->inp_ppcb = tw; 358 TCPSTATES_INC(TCPS_TIME_WAIT); 359 tcp_tw_2msl_reset(tw, 0); 360 } 361 362 /* 363 * If the inpcb owns the sole reference to the socket, then we can 364 * detach and free the socket as it is not needed in time wait. 365 */ 366 if (inp->inp_flags & INP_SOCKREF) { 367 KASSERT(so->so_state & SS_PROTOREF, 368 ("tcp_twstart: !SS_PROTOREF")); 369 inp->inp_flags &= ~INP_SOCKREF; 370 INP_WUNLOCK(inp); 371 SOCK_LOCK(so); 372 so->so_state &= ~SS_PROTOREF; 373 sofree(so); 374 } else 375 INP_WUNLOCK(inp); 376 } 377 378 /* 379 * Returns 1 if the TIME_WAIT state was killed and we should start over, 380 * looking for a pcb in the listen state. Returns 0 otherwise. 381 * 382 * For pure SYN-segments the PCB shall be read-locked and the tcpopt pointer 383 * may be NULL. For the rest write-lock and valid tcpopt. 384 */ 385 int 386 tcp_twcheck(struct inpcb *inp, struct tcpopt *to, struct tcphdr *th, 387 struct mbuf *m, int tlen) 388 { 389 struct tcptw *tw; 390 int thflags; 391 tcp_seq seq; 392 393 NET_EPOCH_ASSERT(); 394 INP_LOCK_ASSERT(inp); 395 396 /* 397 * XXXRW: Time wait state for inpcb has been recycled, but inpcb is 398 * still present. This is undesirable, but temporarily necessary 399 * until we work out how to handle inpcb's who's timewait state has 400 * been removed. 401 */ 402 tw = intotw(inp); 403 if (tw == NULL) 404 goto drop; 405 406 thflags = th->th_flags; 407 #ifdef INVARIANTS 408 if ((thflags & (TH_SYN | TH_ACK)) == TH_SYN) 409 INP_RLOCK_ASSERT(inp); 410 else { 411 INP_WLOCK_ASSERT(inp); 412 KASSERT(to != NULL, 413 ("%s: called without options on a non-SYN segment", 414 __func__)); 415 } 416 #endif 417 418 /* 419 * NOTE: for FIN_WAIT_2 (to be added later), 420 * must validate sequence number before accepting RST 421 */ 422 423 /* 424 * If the segment contains RST: 425 * Drop the segment - see Stevens, vol. 2, p. 964 and 426 * RFC 1337. 427 */ 428 if (thflags & TH_RST) 429 goto drop; 430 431 #if 0 432 /* PAWS not needed at the moment */ 433 /* 434 * RFC 1323 PAWS: If we have a timestamp reply on this segment 435 * and it's less than ts_recent, drop it. 436 */ 437 if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent && 438 TSTMP_LT(to.to_tsval, tp->ts_recent)) { 439 if ((thflags & TH_ACK) == 0) 440 goto drop; 441 goto ack; 442 } 443 /* 444 * ts_recent is never updated because we never accept new segments. 445 */ 446 #endif 447 448 /* 449 * If a new connection request is received 450 * while in TIME_WAIT, drop the old connection 451 * and start over if the sequence numbers 452 * are above the previous ones. 453 * Allow UDP port number changes in this case. 454 */ 455 if ((thflags & TH_SYN) && SEQ_GT(th->th_seq, tw->rcv_nxt)) { 456 /* 457 * In case we can't upgrade our lock just pretend we have 458 * lost this packet. 459 */ 460 if (((thflags & (TH_SYN | TH_ACK)) == TH_SYN) && 461 INP_TRY_UPGRADE(inp) == 0) 462 goto drop; 463 tcp_twclose(tw, 0); 464 return (1); 465 } 466 467 /* 468 * Send RST if UDP port numbers don't match 469 */ 470 if (tw->t_port != m->m_pkthdr.tcp_tun_port) { 471 if (th->th_flags & TH_ACK) { 472 tcp_respond(NULL, mtod(m, void *), th, m, 473 (tcp_seq)0, th->th_ack, TH_RST); 474 } else { 475 if (th->th_flags & TH_SYN) 476 tlen++; 477 if (th->th_flags & TH_FIN) 478 tlen++; 479 tcp_respond(NULL, mtod(m, void *), th, m, 480 th->th_seq+tlen, (tcp_seq)0, TH_RST|TH_ACK); 481 } 482 INP_UNLOCK(inp); 483 return (0); 484 } 485 486 /* 487 * Drop the segment if it does not contain an ACK. 488 */ 489 if ((thflags & TH_ACK) == 0) 490 goto drop; 491 492 INP_WLOCK_ASSERT(inp); 493 494 /* 495 * If timestamps were negotiated during SYN/ACK and a 496 * segment without a timestamp is received, silently drop 497 * the segment, unless the missing timestamps are tolerated. 498 * See section 3.2 of RFC 7323. 499 */ 500 if (((to->to_flags & TOF_TS) == 0) && (tw->t_recent != 0) && 501 (V_tcp_tolerate_missing_ts == 0)) { 502 goto drop; 503 } 504 505 /* 506 * Reset the 2MSL timer if this is a duplicate FIN. 507 */ 508 if (thflags & TH_FIN) { 509 seq = th->th_seq + tlen + (thflags & TH_SYN ? 1 : 0); 510 if (seq + 1 == tw->rcv_nxt) 511 tcp_tw_2msl_reset(tw, 1); 512 } 513 514 /* 515 * Acknowledge the segment if it has data or is not a duplicate ACK. 516 */ 517 if (thflags != TH_ACK || tlen != 0 || 518 th->th_seq != tw->rcv_nxt || th->th_ack != tw->snd_nxt) { 519 TCP_PROBE5(receive, NULL, NULL, m, NULL, th); 520 tcp_twrespond(tw, TH_ACK); 521 goto dropnoprobe; 522 } 523 drop: 524 TCP_PROBE5(receive, NULL, NULL, m, NULL, th); 525 dropnoprobe: 526 INP_UNLOCK(inp); 527 m_freem(m); 528 return (0); 529 } 530 531 void 532 tcp_twclose(struct tcptw *tw, int reuse) 533 { 534 struct socket *so; 535 struct inpcb *inp; 536 537 /* 538 * At this point, we are in one of two situations: 539 * 540 * (1) We have no socket, just an inpcb<->twtcp pair. We can free 541 * all state. 542 * 543 * (2) We have a socket -- if we own a reference, release it and 544 * notify the socket layer. 545 */ 546 inp = tw->tw_inpcb; 547 KASSERT((inp->inp_flags & INP_TIMEWAIT), ("tcp_twclose: !timewait")); 548 KASSERT(intotw(inp) == tw, ("tcp_twclose: inp_ppcb != tw")); 549 NET_EPOCH_ASSERT(); 550 INP_WLOCK_ASSERT(inp); 551 552 tcp_tw_2msl_stop(tw, reuse); 553 inp->inp_ppcb = NULL; 554 in_pcbdrop(inp); 555 556 so = inp->inp_socket; 557 if (so != NULL) { 558 /* 559 * If there's a socket, handle two cases: first, we own a 560 * strong reference, which we will now release, or we don't 561 * in which case another reference exists (XXXRW: think 562 * about this more), and we don't need to take action. 563 */ 564 if (inp->inp_flags & INP_SOCKREF) { 565 inp->inp_flags &= ~INP_SOCKREF; 566 INP_WUNLOCK(inp); 567 SOCK_LOCK(so); 568 KASSERT(so->so_state & SS_PROTOREF, 569 ("tcp_twclose: INP_SOCKREF && !SS_PROTOREF")); 570 so->so_state &= ~SS_PROTOREF; 571 sofree(so); 572 } else { 573 /* 574 * If we don't own the only reference, the socket and 575 * inpcb need to be left around to be handled by 576 * tcp_usr_detach() later. 577 */ 578 INP_WUNLOCK(inp); 579 } 580 } else { 581 /* 582 * The socket has been already cleaned-up for us, only free the 583 * inpcb. 584 */ 585 in_pcbfree(inp); 586 } 587 TCPSTAT_INC(tcps_closed); 588 } 589 590 static int 591 tcp_twrespond(struct tcptw *tw, int flags) 592 { 593 struct inpcb *inp = tw->tw_inpcb; 594 #if defined(INET6) || defined(INET) 595 struct tcphdr *th = NULL; 596 #endif 597 struct mbuf *m; 598 #ifdef INET 599 struct ip *ip = NULL; 600 #endif 601 u_int hdrlen, optlen, ulen; 602 int error = 0; /* Keep compiler happy */ 603 struct tcpopt to; 604 #ifdef INET6 605 struct ip6_hdr *ip6 = NULL; 606 int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6; 607 #endif 608 struct udphdr *udp = NULL; 609 hdrlen = 0; /* Keep compiler happy */ 610 611 INP_WLOCK_ASSERT(inp); 612 613 m = m_gethdr(M_NOWAIT, MT_DATA); 614 if (m == NULL) 615 return (ENOBUFS); 616 m->m_data += max_linkhdr; 617 618 #ifdef MAC 619 mac_inpcb_create_mbuf(inp, m); 620 #endif 621 622 #ifdef INET6 623 if (isipv6) { 624 hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 625 ip6 = mtod(m, struct ip6_hdr *); 626 if (tw->t_port) { 627 udp = (struct udphdr *)(ip6 + 1); 628 hdrlen += sizeof(struct udphdr); 629 udp->uh_sport = htons(V_tcp_udp_tunneling_port); 630 udp->uh_dport = tw->t_port; 631 ulen = (hdrlen - sizeof(struct ip6_hdr)); 632 th = (struct tcphdr *)(udp + 1); 633 } else 634 th = (struct tcphdr *)(ip6 + 1); 635 tcpip_fillheaders(inp, tw->t_port, ip6, th); 636 } 637 #endif 638 #if defined(INET6) && defined(INET) 639 else 640 #endif 641 #ifdef INET 642 { 643 hdrlen = sizeof(struct tcpiphdr); 644 ip = mtod(m, struct ip *); 645 if (tw->t_port) { 646 udp = (struct udphdr *)(ip + 1); 647 hdrlen += sizeof(struct udphdr); 648 udp->uh_sport = htons(V_tcp_udp_tunneling_port); 649 udp->uh_dport = tw->t_port; 650 ulen = (hdrlen - sizeof(struct ip)); 651 th = (struct tcphdr *)(udp + 1); 652 } else 653 th = (struct tcphdr *)(ip + 1); 654 tcpip_fillheaders(inp, tw->t_port, ip, th); 655 } 656 #endif 657 to.to_flags = 0; 658 659 /* 660 * Send a timestamp and echo-reply if both our side and our peer 661 * have sent timestamps in our SYN's and this is not a RST. 662 */ 663 if (tw->t_recent && flags == TH_ACK) { 664 to.to_flags |= TOF_TS; 665 to.to_tsval = tcp_ts_getticks() + tw->ts_offset; 666 to.to_tsecr = tw->t_recent; 667 } 668 optlen = tcp_addoptions(&to, (u_char *)(th + 1)); 669 670 if (udp) { 671 ulen += optlen; 672 udp->uh_ulen = htons(ulen); 673 } 674 m->m_len = hdrlen + optlen; 675 m->m_pkthdr.len = m->m_len; 676 677 KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small")); 678 679 th->th_seq = htonl(tw->snd_nxt); 680 th->th_ack = htonl(tw->rcv_nxt); 681 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 682 th->th_flags = flags; 683 th->th_win = htons(tw->last_win); 684 685 #ifdef INET6 686 if (isipv6) { 687 if (tw->t_port) { 688 m->m_pkthdr.csum_flags = CSUM_UDP_IPV6; 689 m->m_pkthdr.csum_data = offsetof(struct udphdr, uh_sum); 690 udp->uh_sum = in6_cksum_pseudo(ip6, ulen, IPPROTO_UDP, 0); 691 th->th_sum = htons(0); 692 } else { 693 m->m_pkthdr.csum_flags = CSUM_TCP_IPV6; 694 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 695 th->th_sum = in6_cksum_pseudo(ip6, 696 sizeof(struct tcphdr) + optlen, IPPROTO_TCP, 0); 697 } 698 ip6->ip6_hlim = in6_selecthlim(inp, NULL); 699 TCP_PROBE5(send, NULL, NULL, ip6, NULL, th); 700 error = ip6_output(m, inp->in6p_outputopts, NULL, 701 (tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp); 702 } 703 #endif 704 #if defined(INET6) && defined(INET) 705 else 706 #endif 707 #ifdef INET 708 { 709 if (tw->t_port) { 710 m->m_pkthdr.csum_flags = CSUM_UDP; 711 m->m_pkthdr.csum_data = offsetof(struct udphdr, uh_sum); 712 udp->uh_sum = in_pseudo(ip->ip_src.s_addr, 713 ip->ip_dst.s_addr, htons(ulen + IPPROTO_UDP)); 714 th->th_sum = htons(0); 715 } else { 716 m->m_pkthdr.csum_flags = CSUM_TCP; 717 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 718 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 719 htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP)); 720 } 721 ip->ip_len = htons(m->m_pkthdr.len); 722 if (V_path_mtu_discovery) 723 ip->ip_off |= htons(IP_DF); 724 TCP_PROBE5(send, NULL, NULL, ip, NULL, th); 725 error = ip_output(m, inp->inp_options, NULL, 726 ((tw->tw_so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0), 727 NULL, inp); 728 } 729 #endif 730 if (flags & TH_ACK) 731 TCPSTAT_INC(tcps_sndacks); 732 else 733 TCPSTAT_INC(tcps_sndctrl); 734 TCPSTAT_INC(tcps_sndtotal); 735 return (error); 736 } 737 738 static void 739 tcp_tw_2msl_reset(struct tcptw *tw, int rearm) 740 { 741 742 NET_EPOCH_ASSERT(); 743 INP_WLOCK_ASSERT(tw->tw_inpcb); 744 745 TW_WLOCK(V_tw_lock); 746 if (rearm) 747 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl); 748 tw->tw_time = ticks + 2 * tcp_msl; 749 TAILQ_INSERT_TAIL(&V_twq_2msl, tw, tw_2msl); 750 TW_WUNLOCK(V_tw_lock); 751 } 752 753 static void 754 tcp_tw_2msl_stop(struct tcptw *tw, int reuse) 755 { 756 struct ucred *cred; 757 struct inpcb *inp; 758 int released __unused; 759 760 NET_EPOCH_ASSERT(); 761 762 TW_WLOCK(V_tw_lock); 763 inp = tw->tw_inpcb; 764 tw->tw_inpcb = NULL; 765 766 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl); 767 cred = tw->tw_cred; 768 tw->tw_cred = NULL; 769 TW_WUNLOCK(V_tw_lock); 770 771 if (cred != NULL) 772 crfree(cred); 773 774 released = in_pcbrele_wlocked(inp); 775 KASSERT(!released, ("%s: inp should not be released here", __func__)); 776 777 if (!reuse) 778 uma_zfree(V_tcptw_zone, tw); 779 TCPSTATES_DEC(TCPS_TIME_WAIT); 780 } 781 782 struct tcptw * 783 tcp_tw_2msl_scan(int reuse) 784 { 785 struct tcptw *tw; 786 struct inpcb *inp; 787 788 NET_EPOCH_ASSERT(); 789 790 for (;;) { 791 TW_RLOCK(V_tw_lock); 792 tw = TAILQ_FIRST(&V_twq_2msl); 793 if (tw == NULL || (!reuse && (tw->tw_time - ticks) > 0)) { 794 TW_RUNLOCK(V_tw_lock); 795 break; 796 } 797 KASSERT(tw->tw_inpcb != NULL, ("%s: tw->tw_inpcb == NULL", 798 __func__)); 799 800 inp = tw->tw_inpcb; 801 in_pcbref(inp); 802 TW_RUNLOCK(V_tw_lock); 803 804 INP_WLOCK(inp); 805 tw = intotw(inp); 806 if (in_pcbrele_wlocked(inp)) { 807 if (__predict_true(tw == NULL)) { 808 continue; 809 } else { 810 /* This should not happen as in TIMEWAIT 811 * state the inp should not be destroyed 812 * before its tcptw. If INVARIANTS is 813 * defined panic. 814 */ 815 #ifdef INVARIANTS 816 panic("%s: Panic before an infinite " 817 "loop: INP_TIMEWAIT && (INP_FREED " 818 "|| inp last reference) && tw != " 819 "NULL", __func__); 820 #else 821 log(LOG_ERR, "%s: Avoid an infinite " 822 "loop: INP_TIMEWAIT && (INP_FREED " 823 "|| inp last reference) && tw != " 824 "NULL", __func__); 825 #endif 826 break; 827 } 828 } 829 830 if (tw == NULL) { 831 /* tcp_twclose() has already been called */ 832 INP_WUNLOCK(inp); 833 continue; 834 } 835 836 tcp_twclose(tw, reuse); 837 if (reuse) 838 return tw; 839 } 840 841 return NULL; 842 } 843