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_ipsec.h" 40 #include "opt_tcpdebug.h" 41 42 #include <sys/param.h> 43 #include <sys/systm.h> 44 #include <sys/callout.h> 45 #include <sys/kernel.h> 46 #include <sys/sysctl.h> 47 #include <sys/malloc.h> 48 #include <sys/mbuf.h> 49 #include <sys/priv.h> 50 #include <sys/proc.h> 51 #include <sys/socket.h> 52 #include <sys/socketvar.h> 53 #ifndef INVARIANTS 54 #include <sys/syslog.h> 55 #endif 56 #include <sys/protosw.h> 57 #include <sys/random.h> 58 59 #include <vm/uma.h> 60 61 #include <net/route.h> 62 #include <net/if.h> 63 #include <net/if_var.h> 64 #include <net/vnet.h> 65 66 #include <netinet/in.h> 67 #include <netinet/in_kdtrace.h> 68 #include <netinet/in_pcb.h> 69 #include <netinet/in_systm.h> 70 #include <netinet/in_var.h> 71 #include <netinet/ip.h> 72 #include <netinet/ip_icmp.h> 73 #include <netinet/ip_var.h> 74 #ifdef INET6 75 #include <netinet/ip6.h> 76 #include <netinet6/in6_pcb.h> 77 #include <netinet6/ip6_var.h> 78 #include <netinet6/scope6_var.h> 79 #include <netinet6/nd6.h> 80 #endif 81 #include <netinet/tcp.h> 82 #include <netinet/tcp_fsm.h> 83 #include <netinet/tcp_seq.h> 84 #include <netinet/tcp_timer.h> 85 #include <netinet/tcp_var.h> 86 #include <netinet/tcp_hpts.h> 87 #ifdef INET6 88 #include <netinet6/tcp6_var.h> 89 #endif 90 #include <netinet/tcpip.h> 91 #ifdef TCPDEBUG 92 #include <netinet/tcp_debug.h> 93 #endif 94 #ifdef INET6 95 #include <netinet6/ip6protosw.h> 96 #endif 97 98 #include <netinet/udp.h> 99 #include <netinet/udp_var.h> 100 101 #include <netipsec/ipsec_support.h> 102 103 #include <machine/in_cksum.h> 104 105 #include <security/mac/mac_framework.h> 106 107 VNET_DEFINE_STATIC(uma_zone_t, tcptw_zone); 108 #define V_tcptw_zone VNET(tcptw_zone) 109 static int maxtcptw; 110 111 /* 112 * The timed wait queue contains references to each of the TCP sessions 113 * currently in the TIME_WAIT state. The queue pointers, including the 114 * queue pointers in each tcptw structure, are protected using the global 115 * timewait lock, which must be held over queue iteration and modification. 116 * 117 * Rules on tcptw usage: 118 * - a inpcb is always freed _after_ its tcptw 119 * - a tcptw relies on its inpcb reference counting for memory stability 120 * - a tcptw is dereferenceable only while its inpcb is locked 121 */ 122 VNET_DEFINE_STATIC(TAILQ_HEAD(, tcptw), twq_2msl); 123 #define V_twq_2msl VNET(twq_2msl) 124 125 /* Global timewait lock */ 126 VNET_DEFINE_STATIC(struct rwlock, tw_lock); 127 #define V_tw_lock VNET(tw_lock) 128 129 #define TW_LOCK_INIT(tw, d) rw_init_flags(&(tw), (d), 0) 130 #define TW_LOCK_DESTROY(tw) rw_destroy(&(tw)) 131 #define TW_RLOCK(tw) rw_rlock(&(tw)) 132 #define TW_WLOCK(tw) rw_wlock(&(tw)) 133 #define TW_RUNLOCK(tw) rw_runlock(&(tw)) 134 #define TW_WUNLOCK(tw) rw_wunlock(&(tw)) 135 #define TW_LOCK_ASSERT(tw) rw_assert(&(tw), RA_LOCKED) 136 #define TW_RLOCK_ASSERT(tw) rw_assert(&(tw), RA_RLOCKED) 137 #define TW_WLOCK_ASSERT(tw) rw_assert(&(tw), RA_WLOCKED) 138 #define TW_UNLOCK_ASSERT(tw) rw_assert(&(tw), RA_UNLOCKED) 139 140 static void tcp_tw_2msl_reset(struct tcptw *, int); 141 static void tcp_tw_2msl_stop(struct tcptw *, int); 142 static int tcp_twrespond(struct tcptw *, int); 143 144 static int 145 tcptw_auto_size(void) 146 { 147 int halfrange; 148 149 /* 150 * Max out at half the ephemeral port range so that TIME_WAIT 151 * sockets don't tie up too many ephemeral ports. 152 */ 153 if (V_ipport_lastauto > V_ipport_firstauto) 154 halfrange = (V_ipport_lastauto - V_ipport_firstauto) / 2; 155 else 156 halfrange = (V_ipport_firstauto - V_ipport_lastauto) / 2; 157 /* Protect against goofy port ranges smaller than 32. */ 158 return (imin(imax(halfrange, 32), maxsockets / 5)); 159 } 160 161 static int 162 sysctl_maxtcptw(SYSCTL_HANDLER_ARGS) 163 { 164 int error, new; 165 166 if (maxtcptw == 0) 167 new = tcptw_auto_size(); 168 else 169 new = maxtcptw; 170 error = sysctl_handle_int(oidp, &new, 0, req); 171 if (error == 0 && req->newptr) 172 if (new >= 32) { 173 maxtcptw = new; 174 uma_zone_set_max(V_tcptw_zone, maxtcptw); 175 } 176 return (error); 177 } 178 179 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, maxtcptw, 180 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 181 &maxtcptw, 0, sysctl_maxtcptw, "IU", 182 "Maximum number of compressed TCP TIME_WAIT entries"); 183 184 VNET_DEFINE_STATIC(bool, nolocaltimewait) = true; 185 #define V_nolocaltimewait VNET(nolocaltimewait) 186 SYSCTL_BOOL(_net_inet_tcp, OID_AUTO, nolocaltimewait, CTLFLAG_VNET | CTLFLAG_RW, 187 &VNET_NAME(nolocaltimewait), true, 188 "Do not create compressed TCP TIME_WAIT entries for local connections"); 189 190 void 191 tcp_tw_zone_change(void) 192 { 193 194 if (maxtcptw == 0) 195 uma_zone_set_max(V_tcptw_zone, tcptw_auto_size()); 196 } 197 198 void 199 tcp_tw_init(void) 200 { 201 202 V_tcptw_zone = uma_zcreate("tcptw", sizeof(struct tcptw), 203 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 204 TUNABLE_INT_FETCH("net.inet.tcp.maxtcptw", &maxtcptw); 205 if (maxtcptw == 0) 206 uma_zone_set_max(V_tcptw_zone, tcptw_auto_size()); 207 else 208 uma_zone_set_max(V_tcptw_zone, maxtcptw); 209 TAILQ_INIT(&V_twq_2msl); 210 TW_LOCK_INIT(V_tw_lock, "tcptw"); 211 } 212 213 #ifdef VIMAGE 214 void 215 tcp_tw_destroy(void) 216 { 217 struct tcptw *tw; 218 struct epoch_tracker et; 219 220 NET_EPOCH_ENTER(et); 221 while ((tw = TAILQ_FIRST(&V_twq_2msl)) != NULL) 222 tcp_twclose(tw, 0); 223 NET_EPOCH_EXIT(et); 224 225 TW_LOCK_DESTROY(V_tw_lock); 226 uma_zdestroy(V_tcptw_zone); 227 } 228 #endif 229 230 /* 231 * Move a TCP connection into TIME_WAIT state. 232 * tcbinfo is locked. 233 * inp is locked, and is unlocked before returning. 234 */ 235 void 236 tcp_twstart(struct tcpcb *tp) 237 { 238 struct tcptw twlocal, *tw; 239 struct inpcb *inp = tp->t_inpcb; 240 struct socket *so; 241 uint32_t recwin; 242 bool acknow, local; 243 #ifdef INET6 244 bool isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6; 245 #endif 246 247 NET_EPOCH_ASSERT(); 248 INP_WLOCK_ASSERT(inp); 249 250 /* A dropped inp should never transition to TIME_WAIT state. */ 251 KASSERT((inp->inp_flags & INP_DROPPED) == 0, ("tcp_twstart: " 252 "(inp->inp_flags & INP_DROPPED) != 0")); 253 254 if (V_nolocaltimewait) { 255 #ifdef INET6 256 if (isipv6) 257 local = in6_localaddr(&inp->in6p_faddr); 258 else 259 #endif 260 #ifdef INET 261 local = in_localip(inp->inp_faddr); 262 #else 263 local = false; 264 #endif 265 } else 266 local = false; 267 268 /* 269 * For use only by DTrace. We do not reference the state 270 * after this point so modifying it in place is not a problem. 271 */ 272 tcp_state_change(tp, TCPS_TIME_WAIT); 273 274 if (local) 275 tw = &twlocal; 276 else 277 tw = uma_zalloc(V_tcptw_zone, M_NOWAIT); 278 if (tw == NULL) { 279 /* 280 * Reached limit on total number of TIMEWAIT connections 281 * allowed. Remove a connection from TIMEWAIT queue in LRU 282 * fashion to make room for this connection. 283 * If that fails, use on stack tw at least to be able to 284 * run through tcp_twrespond() and standard tcpcb discard 285 * routine. 286 * 287 * XXX: Check if it possible to always have enough room 288 * in advance based on guarantees provided by uma_zalloc(). 289 */ 290 tw = tcp_tw_2msl_scan(1); 291 if (tw == NULL) { 292 tw = &twlocal; 293 local = true; 294 } 295 } 296 /* 297 * For !local case the tcptw will hold a reference on its inpcb 298 * until tcp_twclose is called. 299 */ 300 tw->tw_inpcb = inp; 301 302 /* 303 * Recover last window size sent. 304 */ 305 so = inp->inp_socket; 306 recwin = lmin(lmax(sbspace(&so->so_rcv), 0), 307 (long)TCP_MAXWIN << tp->rcv_scale); 308 if (recwin < (so->so_rcv.sb_hiwat / 4) && 309 recwin < tp->t_maxseg) 310 recwin = 0; 311 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt) && 312 recwin < (tp->rcv_adv - tp->rcv_nxt)) 313 recwin = (tp->rcv_adv - tp->rcv_nxt); 314 tw->last_win = (u_short)(recwin >> tp->rcv_scale); 315 316 /* 317 * Set t_recent if timestamps are used on the connection. 318 */ 319 if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) == 320 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) { 321 tw->t_recent = tp->ts_recent; 322 tw->ts_offset = tp->ts_offset; 323 } else { 324 tw->t_recent = 0; 325 tw->ts_offset = 0; 326 } 327 328 tw->snd_nxt = tp->snd_nxt; 329 tw->t_port = tp->t_port; 330 tw->rcv_nxt = tp->rcv_nxt; 331 tw->tw_time = 0; 332 tw->tw_flags = tp->t_flags; 333 334 /* XXX 335 * If this code will 336 * be used for fin-wait-2 state also, then we may need 337 * a ts_recent from the last segment. 338 */ 339 acknow = tp->t_flags & TF_ACKNOW; 340 341 /* 342 * First, discard tcpcb state, which includes stopping its timers and 343 * freeing it. tcp_discardcb() used to also release the inpcb, but 344 * that work is now done in the caller. 345 * 346 * Note: soisdisconnected() call used to be made in tcp_discardcb(), 347 * and might not be needed here any longer. 348 */ 349 #ifdef TCPHPTS 350 tcp_hpts_remove(inp); 351 #endif 352 tcp_discardcb(tp); 353 soisdisconnected(so); 354 tw->tw_so_options = so->so_options; 355 inp->inp_flags |= INP_TIMEWAIT; 356 if (acknow) 357 tcp_twrespond(tw, TH_ACK); 358 if (local) 359 in_pcbdrop(inp); 360 else { 361 in_pcbref(inp); /* Reference from tw */ 362 tw->tw_cred = crhold(so->so_cred); 363 inp->inp_ppcb = tw; 364 TCPSTATES_INC(TCPS_TIME_WAIT); 365 tcp_tw_2msl_reset(tw, 0); 366 } 367 368 /* 369 * If the inpcb owns the sole reference to the socket, then we can 370 * detach and free the socket as it is not needed in time wait. 371 */ 372 if (inp->inp_flags & INP_SOCKREF) { 373 KASSERT(so->so_state & SS_PROTOREF, 374 ("tcp_twstart: !SS_PROTOREF")); 375 inp->inp_flags &= ~INP_SOCKREF; 376 INP_WUNLOCK(inp); 377 SOCK_LOCK(so); 378 so->so_state &= ~SS_PROTOREF; 379 sofree(so); 380 } else 381 INP_WUNLOCK(inp); 382 } 383 384 /* 385 * Returns 1 if the TIME_WAIT state was killed and we should start over, 386 * looking for a pcb in the listen state. Returns 0 otherwise. 387 * 388 * For pure SYN-segments the PCB shall be read-locked and the tcpopt pointer 389 * may be NULL. For the rest write-lock and valid tcpopt. 390 */ 391 int 392 tcp_twcheck(struct inpcb *inp, struct tcpopt *to, struct tcphdr *th, 393 struct mbuf *m, int tlen) 394 { 395 struct tcptw *tw; 396 int thflags; 397 tcp_seq seq; 398 399 NET_EPOCH_ASSERT(); 400 INP_LOCK_ASSERT(inp); 401 402 /* 403 * XXXRW: Time wait state for inpcb has been recycled, but inpcb is 404 * still present. This is undesirable, but temporarily necessary 405 * until we work out how to handle inpcb's who's timewait state has 406 * been removed. 407 */ 408 tw = intotw(inp); 409 if (tw == NULL) 410 goto drop; 411 412 thflags = th->th_flags; 413 #ifdef INVARIANTS 414 if ((thflags & (TH_SYN | TH_ACK)) == TH_SYN) 415 INP_RLOCK_ASSERT(inp); 416 else { 417 INP_WLOCK_ASSERT(inp); 418 KASSERT(to != NULL, 419 ("%s: called without options on a non-SYN segment", 420 __func__)); 421 } 422 #endif 423 424 /* 425 * NOTE: for FIN_WAIT_2 (to be added later), 426 * must validate sequence number before accepting RST 427 */ 428 429 /* 430 * If the segment contains RST: 431 * Drop the segment - see Stevens, vol. 2, p. 964 and 432 * RFC 1337. 433 */ 434 if (thflags & TH_RST) 435 goto drop; 436 437 #if 0 438 /* PAWS not needed at the moment */ 439 /* 440 * RFC 1323 PAWS: If we have a timestamp reply on this segment 441 * and it's less than ts_recent, drop it. 442 */ 443 if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent && 444 TSTMP_LT(to.to_tsval, tp->ts_recent)) { 445 if ((thflags & TH_ACK) == 0) 446 goto drop; 447 goto ack; 448 } 449 /* 450 * ts_recent is never updated because we never accept new segments. 451 */ 452 #endif 453 454 /* 455 * If a new connection request is received 456 * while in TIME_WAIT, drop the old connection 457 * and start over if the sequence numbers 458 * are above the previous ones. 459 * Allow UDP port number changes in this case. 460 */ 461 if ((thflags & TH_SYN) && SEQ_GT(th->th_seq, tw->rcv_nxt)) { 462 /* 463 * In case we can't upgrade our lock just pretend we have 464 * lost this packet. 465 */ 466 if (((thflags & (TH_SYN | TH_ACK)) == TH_SYN) && 467 INP_TRY_UPGRADE(inp) == 0) 468 goto drop; 469 tcp_twclose(tw, 0); 470 TCPSTAT_INC(tcps_tw_recycles); 471 return (1); 472 } 473 474 /* 475 * Send RST if UDP port numbers don't match 476 */ 477 if (tw->t_port != m->m_pkthdr.tcp_tun_port) { 478 if (th->th_flags & TH_ACK) { 479 tcp_respond(NULL, mtod(m, void *), th, m, 480 (tcp_seq)0, th->th_ack, TH_RST); 481 } else { 482 if (th->th_flags & TH_SYN) 483 tlen++; 484 if (th->th_flags & TH_FIN) 485 tlen++; 486 tcp_respond(NULL, mtod(m, void *), th, m, 487 th->th_seq+tlen, (tcp_seq)0, TH_RST|TH_ACK); 488 } 489 INP_UNLOCK(inp); 490 TCPSTAT_INC(tcps_tw_resets); 491 return (0); 492 } 493 494 /* 495 * Drop the segment if it does not contain an ACK. 496 */ 497 if ((thflags & TH_ACK) == 0) 498 goto drop; 499 500 INP_WLOCK_ASSERT(inp); 501 502 /* 503 * If timestamps were negotiated during SYN/ACK and a 504 * segment without a timestamp is received, silently drop 505 * the segment, unless the missing timestamps are tolerated. 506 * See section 3.2 of RFC 7323. 507 */ 508 if (((to->to_flags & TOF_TS) == 0) && (tw->t_recent != 0) && 509 (V_tcp_tolerate_missing_ts == 0)) { 510 goto drop; 511 } 512 513 /* 514 * Reset the 2MSL timer if this is a duplicate FIN. 515 */ 516 if (thflags & TH_FIN) { 517 seq = th->th_seq + tlen + (thflags & TH_SYN ? 1 : 0); 518 if (seq + 1 == tw->rcv_nxt) 519 tcp_tw_2msl_reset(tw, 1); 520 } 521 522 /* 523 * Acknowledge the segment if it has data or is not a duplicate ACK. 524 */ 525 if (thflags != TH_ACK || tlen != 0 || 526 th->th_seq != tw->rcv_nxt || th->th_ack != tw->snd_nxt) { 527 TCP_PROBE5(receive, NULL, NULL, m, NULL, th); 528 tcp_twrespond(tw, TH_ACK); 529 TCPSTAT_INC(tcps_tw_responds); 530 goto dropnoprobe; 531 } 532 drop: 533 TCP_PROBE5(receive, NULL, NULL, m, NULL, th); 534 dropnoprobe: 535 INP_UNLOCK(inp); 536 m_freem(m); 537 return (0); 538 } 539 540 void 541 tcp_twclose(struct tcptw *tw, int reuse) 542 { 543 struct socket *so; 544 struct inpcb *inp; 545 546 /* 547 * At this point, we are in one of two situations: 548 * 549 * (1) We have no socket, just an inpcb<->twtcp pair. We can free 550 * all state. 551 * 552 * (2) We have a socket -- if we own a reference, release it and 553 * notify the socket layer. 554 */ 555 inp = tw->tw_inpcb; 556 KASSERT((inp->inp_flags & INP_TIMEWAIT), ("tcp_twclose: !timewait")); 557 KASSERT(intotw(inp) == tw, ("tcp_twclose: inp_ppcb != tw")); 558 NET_EPOCH_ASSERT(); 559 INP_WLOCK_ASSERT(inp); 560 561 tcp_tw_2msl_stop(tw, reuse); 562 inp->inp_ppcb = NULL; 563 in_pcbdrop(inp); 564 565 so = inp->inp_socket; 566 if (so != NULL) { 567 /* 568 * If there's a socket, handle two cases: first, we own a 569 * strong reference, which we will now release, or we don't 570 * in which case another reference exists (XXXRW: think 571 * about this more), and we don't need to take action. 572 */ 573 if (inp->inp_flags & INP_SOCKREF) { 574 inp->inp_flags &= ~INP_SOCKREF; 575 INP_WUNLOCK(inp); 576 SOCK_LOCK(so); 577 KASSERT(so->so_state & SS_PROTOREF, 578 ("tcp_twclose: INP_SOCKREF && !SS_PROTOREF")); 579 so->so_state &= ~SS_PROTOREF; 580 sofree(so); 581 } else { 582 /* 583 * If we don't own the only reference, the socket and 584 * inpcb need to be left around to be handled by 585 * tcp_usr_detach() later. 586 */ 587 INP_WUNLOCK(inp); 588 } 589 } else { 590 /* 591 * The socket has been already cleaned-up for us, only free the 592 * inpcb. 593 */ 594 in_pcbfree(inp); 595 } 596 TCPSTAT_INC(tcps_closed); 597 } 598 599 static int 600 tcp_twrespond(struct tcptw *tw, int flags) 601 { 602 struct inpcb *inp = tw->tw_inpcb; 603 #if defined(INET6) || defined(INET) 604 struct tcphdr *th = NULL; 605 #endif 606 struct mbuf *m; 607 #ifdef INET 608 struct ip *ip = NULL; 609 #endif 610 u_int hdrlen, optlen, ulen; 611 int error = 0; /* Keep compiler happy */ 612 struct tcpopt to; 613 #ifdef INET6 614 struct ip6_hdr *ip6 = NULL; 615 int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6; 616 #endif 617 struct udphdr *udp = NULL; 618 hdrlen = 0; /* Keep compiler happy */ 619 620 INP_WLOCK_ASSERT(inp); 621 622 m = m_gethdr(M_NOWAIT, MT_DATA); 623 if (m == NULL) 624 return (ENOBUFS); 625 m->m_data += max_linkhdr; 626 627 #ifdef MAC 628 mac_inpcb_create_mbuf(inp, m); 629 #endif 630 631 #ifdef INET6 632 if (isipv6) { 633 hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 634 ip6 = mtod(m, struct ip6_hdr *); 635 if (tw->t_port) { 636 udp = (struct udphdr *)(ip6 + 1); 637 hdrlen += sizeof(struct udphdr); 638 udp->uh_sport = htons(V_tcp_udp_tunneling_port); 639 udp->uh_dport = tw->t_port; 640 ulen = (hdrlen - sizeof(struct ip6_hdr)); 641 th = (struct tcphdr *)(udp + 1); 642 } else 643 th = (struct tcphdr *)(ip6 + 1); 644 tcpip_fillheaders(inp, tw->t_port, ip6, th); 645 } 646 #endif 647 #if defined(INET6) && defined(INET) 648 else 649 #endif 650 #ifdef INET 651 { 652 hdrlen = sizeof(struct tcpiphdr); 653 ip = mtod(m, struct ip *); 654 if (tw->t_port) { 655 udp = (struct udphdr *)(ip + 1); 656 hdrlen += sizeof(struct udphdr); 657 udp->uh_sport = htons(V_tcp_udp_tunneling_port); 658 udp->uh_dport = tw->t_port; 659 ulen = (hdrlen - sizeof(struct ip)); 660 th = (struct tcphdr *)(udp + 1); 661 } else 662 th = (struct tcphdr *)(ip + 1); 663 tcpip_fillheaders(inp, tw->t_port, ip, th); 664 } 665 #endif 666 to.to_flags = 0; 667 668 /* 669 * Send a timestamp and echo-reply if both our side and our peer 670 * have sent timestamps in our SYN's and this is not a RST. 671 */ 672 if (tw->t_recent && flags == TH_ACK) { 673 to.to_flags |= TOF_TS; 674 to.to_tsval = tcp_ts_getticks() + tw->ts_offset; 675 to.to_tsecr = tw->t_recent; 676 } 677 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 678 if (tw->tw_flags & TF_SIGNATURE) 679 to.to_flags |= TOF_SIGNATURE; 680 #endif 681 optlen = tcp_addoptions(&to, (u_char *)(th + 1)); 682 683 if (udp) { 684 ulen += optlen; 685 udp->uh_ulen = htons(ulen); 686 } 687 m->m_len = hdrlen + optlen; 688 m->m_pkthdr.len = m->m_len; 689 690 KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small")); 691 692 th->th_seq = htonl(tw->snd_nxt); 693 th->th_ack = htonl(tw->rcv_nxt); 694 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 695 th->th_flags = flags; 696 th->th_win = htons(tw->last_win); 697 698 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 699 if (tw->tw_flags & TF_SIGNATURE) { 700 if (!TCPMD5_ENABLED() || 701 TCPMD5_OUTPUT(m, th, to.to_signature) != 0) 702 return (-1); 703 } 704 #endif 705 #ifdef INET6 706 if (isipv6) { 707 if (tw->t_port) { 708 m->m_pkthdr.csum_flags = CSUM_UDP_IPV6; 709 m->m_pkthdr.csum_data = offsetof(struct udphdr, uh_sum); 710 udp->uh_sum = in6_cksum_pseudo(ip6, ulen, IPPROTO_UDP, 0); 711 th->th_sum = htons(0); 712 } else { 713 m->m_pkthdr.csum_flags = CSUM_TCP_IPV6; 714 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 715 th->th_sum = in6_cksum_pseudo(ip6, 716 sizeof(struct tcphdr) + optlen, IPPROTO_TCP, 0); 717 } 718 ip6->ip6_hlim = in6_selecthlim(inp, NULL); 719 TCP_PROBE5(send, NULL, NULL, ip6, NULL, th); 720 error = ip6_output(m, inp->in6p_outputopts, NULL, 721 (tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp); 722 } 723 #endif 724 #if defined(INET6) && defined(INET) 725 else 726 #endif 727 #ifdef INET 728 { 729 if (tw->t_port) { 730 m->m_pkthdr.csum_flags = CSUM_UDP; 731 m->m_pkthdr.csum_data = offsetof(struct udphdr, uh_sum); 732 udp->uh_sum = in_pseudo(ip->ip_src.s_addr, 733 ip->ip_dst.s_addr, htons(ulen + IPPROTO_UDP)); 734 th->th_sum = htons(0); 735 } else { 736 m->m_pkthdr.csum_flags = CSUM_TCP; 737 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 738 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 739 htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP)); 740 } 741 ip->ip_len = htons(m->m_pkthdr.len); 742 if (V_path_mtu_discovery) 743 ip->ip_off |= htons(IP_DF); 744 TCP_PROBE5(send, NULL, NULL, ip, NULL, th); 745 error = ip_output(m, inp->inp_options, NULL, 746 ((tw->tw_so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0), 747 NULL, inp); 748 } 749 #endif 750 if (flags & TH_ACK) 751 TCPSTAT_INC(tcps_sndacks); 752 else 753 TCPSTAT_INC(tcps_sndctrl); 754 TCPSTAT_INC(tcps_sndtotal); 755 return (error); 756 } 757 758 static void 759 tcp_tw_2msl_reset(struct tcptw *tw, int rearm) 760 { 761 762 NET_EPOCH_ASSERT(); 763 INP_WLOCK_ASSERT(tw->tw_inpcb); 764 765 TW_WLOCK(V_tw_lock); 766 if (rearm) 767 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl); 768 tw->tw_time = ticks + 2 * V_tcp_msl; 769 TAILQ_INSERT_TAIL(&V_twq_2msl, tw, tw_2msl); 770 TW_WUNLOCK(V_tw_lock); 771 } 772 773 static void 774 tcp_tw_2msl_stop(struct tcptw *tw, int reuse) 775 { 776 struct ucred *cred; 777 struct inpcb *inp; 778 int released __unused; 779 780 NET_EPOCH_ASSERT(); 781 782 TW_WLOCK(V_tw_lock); 783 inp = tw->tw_inpcb; 784 tw->tw_inpcb = NULL; 785 786 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl); 787 cred = tw->tw_cred; 788 tw->tw_cred = NULL; 789 TW_WUNLOCK(V_tw_lock); 790 791 if (cred != NULL) 792 crfree(cred); 793 794 released = in_pcbrele_wlocked(inp); 795 KASSERT(!released, ("%s: inp should not be released here", __func__)); 796 797 if (!reuse) 798 uma_zfree(V_tcptw_zone, tw); 799 TCPSTATES_DEC(TCPS_TIME_WAIT); 800 } 801 802 struct tcptw * 803 tcp_tw_2msl_scan(int reuse) 804 { 805 struct tcptw *tw; 806 struct inpcb *inp; 807 808 NET_EPOCH_ASSERT(); 809 810 for (;;) { 811 TW_RLOCK(V_tw_lock); 812 tw = TAILQ_FIRST(&V_twq_2msl); 813 if (tw == NULL || (!reuse && (tw->tw_time - ticks) > 0)) { 814 TW_RUNLOCK(V_tw_lock); 815 break; 816 } 817 KASSERT(tw->tw_inpcb != NULL, ("%s: tw->tw_inpcb == NULL", 818 __func__)); 819 820 inp = tw->tw_inpcb; 821 in_pcbref(inp); 822 TW_RUNLOCK(V_tw_lock); 823 824 INP_WLOCK(inp); 825 tw = intotw(inp); 826 if (in_pcbrele_wlocked(inp)) { 827 if (__predict_true(tw == NULL)) { 828 continue; 829 } else { 830 /* This should not happen as in TIMEWAIT 831 * state the inp should not be destroyed 832 * before its tcptw. If INVARIANTS is 833 * defined panic. 834 */ 835 #ifdef INVARIANTS 836 panic("%s: Panic before an infinite " 837 "loop: INP_TIMEWAIT && (INP_FREED " 838 "|| inp last reference) && tw != " 839 "NULL", __func__); 840 #else 841 log(LOG_ERR, "%s: Avoid an infinite " 842 "loop: INP_TIMEWAIT && (INP_FREED " 843 "|| inp last reference) && tw != " 844 "NULL", __func__); 845 #endif 846 break; 847 } 848 } 849 850 if (tw == NULL) { 851 /* tcp_twclose() has already been called */ 852 INP_WUNLOCK(inp); 853 continue; 854 } 855 856 tcp_twclose(tw, reuse); 857 if (reuse) 858 return tw; 859 } 860 861 return NULL; 862 } 863