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 #include <sys/syslog.h> 54 #include <sys/protosw.h> 55 #include <sys/random.h> 56 57 #include <vm/uma.h> 58 59 #include <net/route.h> 60 #include <net/if.h> 61 #include <net/if_var.h> 62 #include <net/vnet.h> 63 64 #include <netinet/in.h> 65 #include <netinet/in_kdtrace.h> 66 #include <netinet/in_pcb.h> 67 #include <netinet/in_systm.h> 68 #include <netinet/in_var.h> 69 #include <netinet/ip.h> 70 #include <netinet/ip_icmp.h> 71 #include <netinet/ip_var.h> 72 #ifdef INET6 73 #include <netinet/ip6.h> 74 #include <netinet6/in6_pcb.h> 75 #include <netinet6/ip6_var.h> 76 #include <netinet6/scope6_var.h> 77 #include <netinet6/nd6.h> 78 #endif 79 #include <netinet/tcp.h> 80 #include <netinet/tcp_fsm.h> 81 #include <netinet/tcp_seq.h> 82 #include <netinet/tcp_timer.h> 83 #include <netinet/tcp_var.h> 84 #include <netinet/tcp_hpts.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 99 #include <netipsec/ipsec_support.h> 100 101 #include <machine/in_cksum.h> 102 103 #include <security/mac/mac_framework.h> 104 105 VNET_DEFINE_STATIC(uma_zone_t, tcptw_zone); 106 #define V_tcptw_zone VNET(tcptw_zone) 107 static int maxtcptw; 108 109 /* 110 * The timed wait queue contains references to each of the TCP sessions 111 * currently in the TIME_WAIT state. The queue pointers, including the 112 * queue pointers in each tcptw structure, are protected using the global 113 * timewait lock, which must be held over queue iteration and modification. 114 * 115 * Rules on tcptw usage: 116 * - a inpcb is always freed _after_ its tcptw 117 * - a tcptw relies on its inpcb reference counting for memory stability 118 * - a tcptw is dereferenceable only while its inpcb is locked 119 */ 120 VNET_DEFINE_STATIC(TAILQ_HEAD(, tcptw), twq_2msl); 121 #define V_twq_2msl VNET(twq_2msl) 122 123 /* Global timewait lock */ 124 VNET_DEFINE_STATIC(struct rwlock, tw_lock); 125 #define V_tw_lock VNET(tw_lock) 126 127 #define TW_LOCK_INIT(tw, d) rw_init_flags(&(tw), (d), 0) 128 #define TW_LOCK_DESTROY(tw) rw_destroy(&(tw)) 129 #define TW_RLOCK(tw) rw_rlock(&(tw)) 130 #define TW_WLOCK(tw) rw_wlock(&(tw)) 131 #define TW_RUNLOCK(tw) rw_runlock(&(tw)) 132 #define TW_WUNLOCK(tw) rw_wunlock(&(tw)) 133 #define TW_LOCK_ASSERT(tw) rw_assert(&(tw), RA_LOCKED) 134 #define TW_RLOCK_ASSERT(tw) rw_assert(&(tw), RA_RLOCKED) 135 #define TW_WLOCK_ASSERT(tw) rw_assert(&(tw), RA_WLOCKED) 136 #define TW_UNLOCK_ASSERT(tw) rw_assert(&(tw), RA_UNLOCKED) 137 138 static void tcp_tw_2msl_reset(struct tcptw *, int); 139 static void tcp_tw_2msl_stop(struct tcptw *, int); 140 static int tcp_twrespond(struct tcptw *, int); 141 142 static int 143 tcptw_auto_size(void) 144 { 145 int halfrange; 146 147 /* 148 * Max out at half the ephemeral port range so that TIME_WAIT 149 * sockets don't tie up too many ephemeral ports. 150 */ 151 if (V_ipport_lastauto > V_ipport_firstauto) 152 halfrange = (V_ipport_lastauto - V_ipport_firstauto) / 2; 153 else 154 halfrange = (V_ipport_firstauto - V_ipport_lastauto) / 2; 155 /* Protect against goofy port ranges smaller than 32. */ 156 return (imin(imax(halfrange, 32), maxsockets / 5)); 157 } 158 159 static int 160 sysctl_maxtcptw(SYSCTL_HANDLER_ARGS) 161 { 162 int error, new; 163 164 if (maxtcptw == 0) 165 new = tcptw_auto_size(); 166 else 167 new = maxtcptw; 168 error = sysctl_handle_int(oidp, &new, 0, req); 169 if (error == 0 && req->newptr) 170 if (new >= 32) { 171 maxtcptw = new; 172 uma_zone_set_max(V_tcptw_zone, maxtcptw); 173 } 174 return (error); 175 } 176 177 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, maxtcptw, 178 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 179 &maxtcptw, 0, sysctl_maxtcptw, "IU", 180 "Maximum number of compressed TCP TIME_WAIT entries"); 181 182 VNET_DEFINE_STATIC(bool, nolocaltimewait) = true; 183 #define V_nolocaltimewait VNET(nolocaltimewait) 184 SYSCTL_BOOL(_net_inet_tcp, OID_AUTO, nolocaltimewait, CTLFLAG_VNET | CTLFLAG_RW, 185 &VNET_NAME(nolocaltimewait), true, 186 "Do not create compressed TCP TIME_WAIT entries for local connections"); 187 188 void 189 tcp_tw_zone_change(void) 190 { 191 192 if (maxtcptw == 0) 193 uma_zone_set_max(V_tcptw_zone, tcptw_auto_size()); 194 } 195 196 void 197 tcp_tw_init(void) 198 { 199 200 V_tcptw_zone = uma_zcreate("tcptw", sizeof(struct tcptw), 201 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 202 TUNABLE_INT_FETCH("net.inet.tcp.maxtcptw", &maxtcptw); 203 if (maxtcptw == 0) 204 uma_zone_set_max(V_tcptw_zone, tcptw_auto_size()); 205 else 206 uma_zone_set_max(V_tcptw_zone, maxtcptw); 207 TAILQ_INIT(&V_twq_2msl); 208 TW_LOCK_INIT(V_tw_lock, "tcptw"); 209 } 210 211 #ifdef VIMAGE 212 void 213 tcp_tw_destroy(void) 214 { 215 struct tcptw *tw; 216 struct epoch_tracker et; 217 218 NET_EPOCH_ENTER(et); 219 while ((tw = TAILQ_FIRST(&V_twq_2msl)) != NULL) 220 tcp_twclose(tw, 0); 221 NET_EPOCH_EXIT(et); 222 223 TW_LOCK_DESTROY(V_tw_lock); 224 uma_zdestroy(V_tcptw_zone); 225 } 226 #endif 227 228 /* 229 * Move a TCP connection into TIME_WAIT state. 230 * tcbinfo is locked. 231 * inp is locked, and is unlocked before returning. 232 */ 233 void 234 tcp_twstart(struct tcpcb *tp) 235 { 236 struct tcptw twlocal, *tw; 237 struct inpcb *inp = tp->t_inpcb; 238 struct socket *so; 239 uint32_t recwin; 240 bool acknow, local; 241 #ifdef INET6 242 bool isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6; 243 #endif 244 245 NET_EPOCH_ASSERT(); 246 INP_WLOCK_ASSERT(inp); 247 248 /* A dropped inp should never transition to TIME_WAIT state. */ 249 KASSERT((inp->inp_flags & INP_DROPPED) == 0, ("tcp_twstart: " 250 "(inp->inp_flags & INP_DROPPED) != 0")); 251 252 if (V_nolocaltimewait) { 253 #ifdef INET6 254 if (isipv6) 255 local = in6_localaddr(&inp->in6p_faddr); 256 else 257 #endif 258 #ifdef INET 259 local = in_localip(inp->inp_faddr); 260 #else 261 local = false; 262 #endif 263 } else 264 local = false; 265 266 /* 267 * For use only by DTrace. We do not reference the state 268 * after this point so modifying it in place is not a problem. 269 */ 270 tcp_state_change(tp, TCPS_TIME_WAIT); 271 272 if (local) 273 tw = &twlocal; 274 else 275 tw = uma_zalloc(V_tcptw_zone, M_NOWAIT); 276 if (tw == NULL) { 277 /* 278 * Reached limit on total number of TIMEWAIT connections 279 * allowed. Remove a connection from TIMEWAIT queue in LRU 280 * fashion to make room for this connection. 281 * If that fails, use on stack tw at least to be able to 282 * run through tcp_twrespond() and standard tcpcb discard 283 * routine. 284 * 285 * XXX: Check if it possible to always have enough room 286 * in advance based on guarantees provided by uma_zalloc(). 287 */ 288 tw = tcp_tw_2msl_scan(1); 289 if (tw == NULL) { 290 tw = &twlocal; 291 local = true; 292 } 293 } 294 /* 295 * For !local case the tcptw will hold a reference on its inpcb 296 * until tcp_twclose is called. 297 */ 298 tw->tw_inpcb = inp; 299 300 /* 301 * Recover last window size sent. 302 */ 303 so = inp->inp_socket; 304 recwin = lmin(lmax(sbspace(&so->so_rcv), 0), 305 (long)TCP_MAXWIN << tp->rcv_scale); 306 if (recwin < (so->so_rcv.sb_hiwat / 4) && 307 recwin < tp->t_maxseg) 308 recwin = 0; 309 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt) && 310 recwin < (tp->rcv_adv - tp->rcv_nxt)) 311 recwin = (tp->rcv_adv - tp->rcv_nxt); 312 tw->last_win = (u_short)(recwin >> tp->rcv_scale); 313 314 /* 315 * Set t_recent if timestamps are used on the connection. 316 */ 317 if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) == 318 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) { 319 tw->t_recent = tp->ts_recent; 320 tw->ts_offset = tp->ts_offset; 321 } else { 322 tw->t_recent = 0; 323 tw->ts_offset = 0; 324 } 325 326 tw->snd_nxt = tp->snd_nxt; 327 tw->t_port = tp->t_port; 328 tw->rcv_nxt = tp->rcv_nxt; 329 tw->tw_time = 0; 330 tw->tw_flags = tp->t_flags; 331 332 /* XXX 333 * If this code will 334 * be used for fin-wait-2 state also, then we may need 335 * a ts_recent from the last segment. 336 */ 337 acknow = tp->t_flags & TF_ACKNOW; 338 339 /* 340 * First, discard tcpcb state, which includes stopping its timers and 341 * freeing it. tcp_discardcb() used to also release the inpcb, but 342 * that work is now done in the caller. 343 * 344 * Note: soisdisconnected() call used to be made in tcp_discardcb(), 345 * and might not be needed here any longer. 346 */ 347 #ifdef TCPHPTS 348 tcp_hpts_remove(inp); 349 #endif 350 tcp_discardcb(tp); 351 soisdisconnected(so); 352 tw->tw_so_options = so->so_options; 353 inp->inp_flags |= INP_TIMEWAIT; 354 if (acknow) 355 tcp_twrespond(tw, TH_ACK); 356 if (local) 357 in_pcbdrop(inp); 358 else { 359 in_pcbref(inp); /* Reference from tw */ 360 tw->tw_cred = crhold(so->so_cred); 361 inp->inp_ppcb = tw; 362 TCPSTATES_INC(TCPS_TIME_WAIT); 363 tcp_tw_2msl_reset(tw, 0); 364 } 365 366 /* 367 * If the inpcb owns the sole reference to the socket, then we can 368 * detach and free the socket as it is not needed in time wait. 369 */ 370 if (inp->inp_flags & INP_SOCKREF) { 371 inp->inp_flags &= ~INP_SOCKREF; 372 INP_WUNLOCK(inp); 373 sorele(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 char *s; 391 int thflags; 392 tcp_seq seq; 393 394 NET_EPOCH_ASSERT(); 395 INP_LOCK_ASSERT(inp); 396 397 /* 398 * XXXRW: Time wait state for inpcb has been recycled, but inpcb is 399 * still present. This is undesirable, but temporarily necessary 400 * until we work out how to handle inpcb's who's timewait state has 401 * been removed. 402 */ 403 tw = intotw(inp); 404 if (tw == NULL) 405 goto drop; 406 407 thflags = tcp_get_flags(th); 408 #ifdef INVARIANTS 409 if ((thflags & (TH_SYN | TH_ACK)) == TH_SYN) 410 INP_RLOCK_ASSERT(inp); 411 else { 412 INP_WLOCK_ASSERT(inp); 413 KASSERT(to != NULL, 414 ("%s: called without options on a non-SYN segment", 415 __func__)); 416 } 417 #endif 418 419 /* 420 * NOTE: for FIN_WAIT_2 (to be added later), 421 * must validate sequence number before accepting RST 422 */ 423 424 /* 425 * If the segment contains RST: 426 * Drop the segment - see Stevens, vol. 2, p. 964 and 427 * RFC 1337. 428 */ 429 if (thflags & TH_RST) 430 goto drop; 431 432 #if 0 433 /* PAWS not needed at the moment */ 434 /* 435 * RFC 1323 PAWS: If we have a timestamp reply on this segment 436 * and it's less than ts_recent, drop it. 437 */ 438 if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent && 439 TSTMP_LT(to.to_tsval, tp->ts_recent)) { 440 if ((thflags & TH_ACK) == 0) 441 goto drop; 442 goto ack; 443 } 444 /* 445 * ts_recent is never updated because we never accept new segments. 446 */ 447 #endif 448 449 /* Honor the drop_synfin sysctl variable. */ 450 if ((thflags & TH_SYN) && (thflags & TH_FIN) && V_drop_synfin) { 451 if ((s = tcp_log_addrs(&inp->inp_inc, th, NULL, NULL))) { 452 log(LOG_DEBUG, "%s; %s: " 453 "SYN|FIN segment ignored (based on " 454 "sysctl setting)\n", s, __func__); 455 free(s, M_TCPLOG); 456 } 457 goto drop; 458 } 459 460 /* 461 * If a new connection request is received 462 * while in TIME_WAIT, drop the old connection 463 * and start over if the sequence numbers 464 * are above the previous ones. 465 * Allow UDP port number changes in this case. 466 */ 467 if (((thflags & (TH_SYN | TH_ACK)) == TH_SYN) && 468 SEQ_GT(th->th_seq, tw->rcv_nxt)) { 469 /* 470 * In case we can't upgrade our lock just pretend we have 471 * lost this packet. 472 */ 473 if (INP_TRY_UPGRADE(inp) == 0) 474 goto drop; 475 tcp_twclose(tw, 0); 476 TCPSTAT_INC(tcps_tw_recycles); 477 return (1); 478 } 479 480 /* 481 * Send RST if UDP port numbers don't match 482 */ 483 if (tw->t_port != m->m_pkthdr.tcp_tun_port) { 484 if (tcp_get_flags(th) & TH_ACK) { 485 tcp_respond(NULL, mtod(m, void *), th, m, 486 (tcp_seq)0, th->th_ack, TH_RST); 487 } else { 488 if (tcp_get_flags(th) & TH_SYN) 489 tlen++; 490 if (tcp_get_flags(th) & TH_FIN) 491 tlen++; 492 tcp_respond(NULL, mtod(m, void *), th, m, 493 th->th_seq+tlen, (tcp_seq)0, TH_RST|TH_ACK); 494 } 495 INP_UNLOCK(inp); 496 TCPSTAT_INC(tcps_tw_resets); 497 return (0); 498 } 499 500 /* 501 * Drop the segment if it does not contain an ACK. 502 */ 503 if ((thflags & TH_ACK) == 0) 504 goto drop; 505 506 INP_WLOCK_ASSERT(inp); 507 508 /* 509 * If timestamps were negotiated during SYN/ACK and a 510 * segment without a timestamp is received, silently drop 511 * the segment, unless the missing timestamps are tolerated. 512 * See section 3.2 of RFC 7323. 513 */ 514 if (((to->to_flags & TOF_TS) == 0) && (tw->t_recent != 0) && 515 (V_tcp_tolerate_missing_ts == 0)) { 516 goto drop; 517 } 518 519 /* 520 * Reset the 2MSL timer if this is a duplicate FIN. 521 */ 522 if (thflags & TH_FIN) { 523 seq = th->th_seq + tlen + (thflags & TH_SYN ? 1 : 0); 524 if (seq + 1 == tw->rcv_nxt) 525 tcp_tw_2msl_reset(tw, 1); 526 } 527 528 /* 529 * Acknowledge the segment if it has data or is not a duplicate ACK. 530 */ 531 if (thflags != TH_ACK || tlen != 0 || 532 th->th_seq != tw->rcv_nxt || th->th_ack != tw->snd_nxt) { 533 TCP_PROBE5(receive, NULL, NULL, m, NULL, th); 534 tcp_twrespond(tw, TH_ACK); 535 TCPSTAT_INC(tcps_tw_responds); 536 goto dropnoprobe; 537 } 538 drop: 539 TCP_PROBE5(receive, NULL, NULL, m, NULL, th); 540 dropnoprobe: 541 INP_UNLOCK(inp); 542 m_freem(m); 543 return (0); 544 } 545 546 void 547 tcp_twclose(struct tcptw *tw, int reuse) 548 { 549 struct socket *so; 550 struct inpcb *inp; 551 552 /* 553 * At this point, we are in one of two situations: 554 * 555 * (1) We have no socket, just an inpcb<->twtcp pair. We can free 556 * all state. 557 * 558 * (2) We have a socket -- if we own a reference, release it and 559 * notify the socket layer. 560 */ 561 inp = tw->tw_inpcb; 562 KASSERT((inp->inp_flags & INP_TIMEWAIT), ("tcp_twclose: !timewait")); 563 KASSERT(intotw(inp) == tw, ("tcp_twclose: inp_ppcb != tw")); 564 NET_EPOCH_ASSERT(); 565 INP_WLOCK_ASSERT(inp); 566 567 tcp_tw_2msl_stop(tw, reuse); 568 inp->inp_ppcb = NULL; 569 in_pcbdrop(inp); 570 571 so = inp->inp_socket; 572 if (so != NULL) { 573 /* 574 * If there's a socket, handle two cases: first, we own a 575 * strong reference, which we will now release, or we don't 576 * in which case another reference exists (XXXRW: think 577 * about this more), and we don't need to take action. 578 */ 579 if (inp->inp_flags & INP_SOCKREF) { 580 inp->inp_flags &= ~INP_SOCKREF; 581 INP_WUNLOCK(inp); 582 sorele(so); 583 } else { 584 /* 585 * If we don't own the only reference, the socket and 586 * inpcb need to be left around to be handled by 587 * tcp_usr_detach() later. 588 */ 589 INP_WUNLOCK(inp); 590 } 591 } else { 592 /* 593 * The socket has been already cleaned-up for us, only free the 594 * inpcb. 595 */ 596 in_pcbfree(inp); 597 } 598 TCPSTAT_INC(tcps_closed); 599 } 600 601 static int 602 tcp_twrespond(struct tcptw *tw, int flags) 603 { 604 struct inpcb *inp = tw->tw_inpcb; 605 #if defined(INET6) || defined(INET) 606 struct tcphdr *th = NULL; 607 #endif 608 struct mbuf *m; 609 #ifdef INET 610 struct ip *ip = NULL; 611 #endif 612 u_int hdrlen, optlen, ulen; 613 int error = 0; /* Keep compiler happy */ 614 struct tcpopt to; 615 #ifdef INET6 616 struct ip6_hdr *ip6 = NULL; 617 int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6; 618 #endif 619 struct udphdr *udp = NULL; 620 hdrlen = 0; /* Keep compiler happy */ 621 622 INP_WLOCK_ASSERT(inp); 623 624 m = m_gethdr(M_NOWAIT, MT_DATA); 625 if (m == NULL) 626 return (ENOBUFS); 627 m->m_data += max_linkhdr; 628 629 #ifdef MAC 630 mac_inpcb_create_mbuf(inp, m); 631 #endif 632 633 #ifdef INET6 634 if (isipv6) { 635 hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 636 ip6 = mtod(m, struct ip6_hdr *); 637 if (tw->t_port) { 638 udp = (struct udphdr *)(ip6 + 1); 639 hdrlen += sizeof(struct udphdr); 640 udp->uh_sport = htons(V_tcp_udp_tunneling_port); 641 udp->uh_dport = tw->t_port; 642 ulen = (hdrlen - sizeof(struct ip6_hdr)); 643 th = (struct tcphdr *)(udp + 1); 644 } else 645 th = (struct tcphdr *)(ip6 + 1); 646 tcpip_fillheaders(inp, tw->t_port, ip6, th); 647 } 648 #endif 649 #if defined(INET6) && defined(INET) 650 else 651 #endif 652 #ifdef INET 653 { 654 hdrlen = sizeof(struct tcpiphdr); 655 ip = mtod(m, struct ip *); 656 if (tw->t_port) { 657 udp = (struct udphdr *)(ip + 1); 658 hdrlen += sizeof(struct udphdr); 659 udp->uh_sport = htons(V_tcp_udp_tunneling_port); 660 udp->uh_dport = tw->t_port; 661 ulen = (hdrlen - sizeof(struct ip)); 662 th = (struct tcphdr *)(udp + 1); 663 } else 664 th = (struct tcphdr *)(ip + 1); 665 tcpip_fillheaders(inp, tw->t_port, ip, th); 666 } 667 #endif 668 to.to_flags = 0; 669 670 /* 671 * Send a timestamp and echo-reply if both our side and our peer 672 * have sent timestamps in our SYN's and this is not a RST. 673 */ 674 if (tw->t_recent && flags == TH_ACK) { 675 to.to_flags |= TOF_TS; 676 to.to_tsval = tcp_ts_getticks() + tw->ts_offset; 677 to.to_tsecr = tw->t_recent; 678 } 679 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 680 if (tw->tw_flags & TF_SIGNATURE) 681 to.to_flags |= TOF_SIGNATURE; 682 #endif 683 optlen = tcp_addoptions(&to, (u_char *)(th + 1)); 684 685 if (udp) { 686 ulen += optlen; 687 udp->uh_ulen = htons(ulen); 688 } 689 m->m_len = hdrlen + optlen; 690 m->m_pkthdr.len = m->m_len; 691 692 KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small")); 693 694 th->th_seq = htonl(tw->snd_nxt); 695 th->th_ack = htonl(tw->rcv_nxt); 696 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 697 tcp_set_flags(th, flags); 698 th->th_win = htons(tw->last_win); 699 700 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 701 if (tw->tw_flags & TF_SIGNATURE) { 702 if (!TCPMD5_ENABLED() || 703 TCPMD5_OUTPUT(m, th, to.to_signature) != 0) 704 return (-1); 705 } 706 #endif 707 #ifdef INET6 708 if (isipv6) { 709 if (tw->t_port) { 710 m->m_pkthdr.csum_flags = CSUM_UDP_IPV6; 711 m->m_pkthdr.csum_data = offsetof(struct udphdr, uh_sum); 712 udp->uh_sum = in6_cksum_pseudo(ip6, ulen, IPPROTO_UDP, 0); 713 th->th_sum = htons(0); 714 } else { 715 m->m_pkthdr.csum_flags = CSUM_TCP_IPV6; 716 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 717 th->th_sum = in6_cksum_pseudo(ip6, 718 sizeof(struct tcphdr) + optlen, IPPROTO_TCP, 0); 719 } 720 ip6->ip6_hlim = in6_selecthlim(inp, NULL); 721 TCP_PROBE5(send, NULL, NULL, ip6, NULL, th); 722 error = ip6_output(m, inp->in6p_outputopts, NULL, 723 (tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp); 724 } 725 #endif 726 #if defined(INET6) && defined(INET) 727 else 728 #endif 729 #ifdef INET 730 { 731 if (tw->t_port) { 732 m->m_pkthdr.csum_flags = CSUM_UDP; 733 m->m_pkthdr.csum_data = offsetof(struct udphdr, uh_sum); 734 udp->uh_sum = in_pseudo(ip->ip_src.s_addr, 735 ip->ip_dst.s_addr, htons(ulen + IPPROTO_UDP)); 736 th->th_sum = htons(0); 737 } else { 738 m->m_pkthdr.csum_flags = CSUM_TCP; 739 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 740 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 741 htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP)); 742 } 743 ip->ip_len = htons(m->m_pkthdr.len); 744 if (V_path_mtu_discovery) 745 ip->ip_off |= htons(IP_DF); 746 TCP_PROBE5(send, NULL, NULL, ip, NULL, th); 747 error = ip_output(m, inp->inp_options, NULL, 748 ((tw->tw_so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0), 749 NULL, inp); 750 } 751 #endif 752 if (flags & TH_ACK) 753 TCPSTAT_INC(tcps_sndacks); 754 else 755 TCPSTAT_INC(tcps_sndctrl); 756 TCPSTAT_INC(tcps_sndtotal); 757 return (error); 758 } 759 760 static void 761 tcp_tw_2msl_reset(struct tcptw *tw, int rearm) 762 { 763 764 NET_EPOCH_ASSERT(); 765 INP_WLOCK_ASSERT(tw->tw_inpcb); 766 767 TW_WLOCK(V_tw_lock); 768 if (rearm) 769 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl); 770 tw->tw_time = ticks + 2 * V_tcp_msl; 771 TAILQ_INSERT_TAIL(&V_twq_2msl, tw, tw_2msl); 772 TW_WUNLOCK(V_tw_lock); 773 } 774 775 static void 776 tcp_tw_2msl_stop(struct tcptw *tw, int reuse) 777 { 778 struct ucred *cred; 779 struct inpcb *inp; 780 int released __unused; 781 782 NET_EPOCH_ASSERT(); 783 784 TW_WLOCK(V_tw_lock); 785 inp = tw->tw_inpcb; 786 tw->tw_inpcb = NULL; 787 788 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl); 789 cred = tw->tw_cred; 790 tw->tw_cred = NULL; 791 TW_WUNLOCK(V_tw_lock); 792 793 if (cred != NULL) 794 crfree(cred); 795 796 released = in_pcbrele_wlocked(inp); 797 KASSERT(!released, ("%s: inp should not be released here", __func__)); 798 799 if (!reuse) 800 uma_zfree(V_tcptw_zone, tw); 801 TCPSTATES_DEC(TCPS_TIME_WAIT); 802 } 803 804 struct tcptw * 805 tcp_tw_2msl_scan(int reuse) 806 { 807 struct tcptw *tw; 808 struct inpcb *inp; 809 810 NET_EPOCH_ASSERT(); 811 812 for (;;) { 813 TW_RLOCK(V_tw_lock); 814 tw = TAILQ_FIRST(&V_twq_2msl); 815 if (tw == NULL || (!reuse && (tw->tw_time - ticks) > 0)) { 816 TW_RUNLOCK(V_tw_lock); 817 break; 818 } 819 KASSERT(tw->tw_inpcb != NULL, ("%s: tw->tw_inpcb == NULL", 820 __func__)); 821 822 inp = tw->tw_inpcb; 823 in_pcbref(inp); 824 TW_RUNLOCK(V_tw_lock); 825 826 INP_WLOCK(inp); 827 tw = intotw(inp); 828 if (in_pcbrele_wlocked(inp)) { 829 if (__predict_true(tw == NULL)) { 830 continue; 831 } else { 832 /* This should not happen as in TIMEWAIT 833 * state the inp should not be destroyed 834 * before its tcptw. If INVARIANTS is 835 * defined panic. 836 */ 837 #ifdef INVARIANTS 838 panic("%s: Panic before an infinite " 839 "loop: INP_TIMEWAIT && (INP_FREED " 840 "|| inp last reference) && tw != " 841 "NULL", __func__); 842 #else 843 log(LOG_ERR, "%s: Avoid an infinite " 844 "loop: INP_TIMEWAIT && (INP_FREED " 845 "|| inp last reference) && tw != " 846 "NULL", __func__); 847 #endif 848 break; 849 } 850 } 851 852 if (tw == NULL) { 853 /* tcp_twclose() has already been called */ 854 INP_WUNLOCK(inp); 855 continue; 856 } 857 858 tcp_twclose(tw, reuse); 859 if (reuse) 860 return tw; 861 } 862 863 return NULL; 864 } 865