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: releng/12.0/sys/netinet/tcp_timewait.c 336937 2018-07-30 21:13:42Z tuexen $");
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 <machine/in_cksum.h>
97
98 #include <security/mac/mac_framework.h>
99
100 VNET_DEFINE_STATIC(uma_zone_t, tcptw_zone);
101 #define V_tcptw_zone VNET(tcptw_zone)
102 static int maxtcptw;
103
104 /*
105 * The timed wait queue contains references to each of the TCP sessions
106 * currently in the TIME_WAIT state. The queue pointers, including the
107 * queue pointers in each tcptw structure, are protected using the global
108 * timewait lock, which must be held over queue iteration and modification.
109 *
110 * Rules on tcptw usage:
111 * - a inpcb is always freed _after_ its tcptw
112 * - a tcptw relies on its inpcb reference counting for memory stability
113 * - a tcptw is dereferenceable only while its inpcb is locked
114 */
115 VNET_DEFINE_STATIC(TAILQ_HEAD(, tcptw), twq_2msl);
116 #define V_twq_2msl VNET(twq_2msl)
117
118 /* Global timewait lock */
119 VNET_DEFINE_STATIC(struct rwlock, tw_lock);
120 #define V_tw_lock VNET(tw_lock)
121
122 #define TW_LOCK_INIT(tw, d) rw_init_flags(&(tw), (d), 0)
123 #define TW_LOCK_DESTROY(tw) rw_destroy(&(tw))
124 #define TW_RLOCK(tw) rw_rlock(&(tw))
125 #define TW_WLOCK(tw) rw_wlock(&(tw))
126 #define TW_RUNLOCK(tw) rw_runlock(&(tw))
127 #define TW_WUNLOCK(tw) rw_wunlock(&(tw))
128 #define TW_LOCK_ASSERT(tw) rw_assert(&(tw), RA_LOCKED)
129 #define TW_RLOCK_ASSERT(tw) rw_assert(&(tw), RA_RLOCKED)
130 #define TW_WLOCK_ASSERT(tw) rw_assert(&(tw), RA_WLOCKED)
131 #define TW_UNLOCK_ASSERT(tw) rw_assert(&(tw), RA_UNLOCKED)
132
133 static void tcp_tw_2msl_reset(struct tcptw *, int);
134 static void tcp_tw_2msl_stop(struct tcptw *, int);
135 static int tcp_twrespond(struct tcptw *, int);
136
137 static int
138 tcptw_auto_size(void)
139 {
140 int halfrange;
141
142 /*
143 * Max out at half the ephemeral port range so that TIME_WAIT
144 * sockets don't tie up too many ephemeral ports.
145 */
146 if (V_ipport_lastauto > V_ipport_firstauto)
147 halfrange = (V_ipport_lastauto - V_ipport_firstauto) / 2;
148 else
149 halfrange = (V_ipport_firstauto - V_ipport_lastauto) / 2;
150 /* Protect against goofy port ranges smaller than 32. */
151 return (imin(imax(halfrange, 32), maxsockets / 5));
152 }
153
154 static int
155 sysctl_maxtcptw(SYSCTL_HANDLER_ARGS)
156 {
157 int error, new;
158
159 if (maxtcptw == 0)
160 new = tcptw_auto_size();
161 else
162 new = maxtcptw;
163 error = sysctl_handle_int(oidp, &new, 0, req);
164 if (error == 0 && req->newptr)
165 if (new >= 32) {
166 maxtcptw = new;
167 uma_zone_set_max(V_tcptw_zone, maxtcptw);
168 }
169 return (error);
170 }
171
172 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, maxtcptw, CTLTYPE_INT|CTLFLAG_RW,
173 &maxtcptw, 0, sysctl_maxtcptw, "IU",
174 "Maximum number of compressed TCP TIME_WAIT entries");
175
176 VNET_DEFINE_STATIC(int, nolocaltimewait) = 0;
177 #define V_nolocaltimewait VNET(nolocaltimewait)
178 SYSCTL_INT(_net_inet_tcp, OID_AUTO, nolocaltimewait, CTLFLAG_VNET | CTLFLAG_RW,
179 &VNET_NAME(nolocaltimewait), 0,
180 "Do not create compressed TCP TIME_WAIT entries for local connections");
181
182 void
183 tcp_tw_zone_change(void)
184 {
185
186 if (maxtcptw == 0)
187 uma_zone_set_max(V_tcptw_zone, tcptw_auto_size());
188 }
189
190 void
191 tcp_tw_init(void)
192 {
193
194 V_tcptw_zone = uma_zcreate("tcptw", sizeof(struct tcptw),
195 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
196 TUNABLE_INT_FETCH("net.inet.tcp.maxtcptw", &maxtcptw);
197 if (maxtcptw == 0)
198 uma_zone_set_max(V_tcptw_zone, tcptw_auto_size());
199 else
200 uma_zone_set_max(V_tcptw_zone, maxtcptw);
201 TAILQ_INIT(&V_twq_2msl);
202 TW_LOCK_INIT(V_tw_lock, "tcptw");
203 }
204
205 #ifdef VIMAGE
206 void
207 tcp_tw_destroy(void)
208 {
209 struct tcptw *tw;
210 struct epoch_tracker et;
211
212 INP_INFO_RLOCK_ET(&V_tcbinfo, et);
213 while ((tw = TAILQ_FIRST(&V_twq_2msl)) != NULL)
214 tcp_twclose(tw, 0);
215 INP_INFO_RUNLOCK_ET(&V_tcbinfo, et);
216
217 TW_LOCK_DESTROY(V_tw_lock);
218 uma_zdestroy(V_tcptw_zone);
219 }
220 #endif
221
222 /*
223 * Move a TCP connection into TIME_WAIT state.
224 * tcbinfo is locked.
225 * inp is locked, and is unlocked before returning.
226 */
227 void
228 tcp_twstart(struct tcpcb *tp)
229 {
230 struct tcptw twlocal, *tw;
231 struct inpcb *inp = tp->t_inpcb;
232 struct socket *so;
233 uint32_t recwin;
234 bool acknow, local;
235 #ifdef INET6
236 bool isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6;
237 #endif
238
239 INP_INFO_RLOCK_ASSERT(&V_tcbinfo);
240 INP_WLOCK_ASSERT(inp);
241
242 /* A dropped inp should never transition to TIME_WAIT state. */
243 KASSERT((inp->inp_flags & INP_DROPPED) == 0, ("tcp_twstart: "
244 "(inp->inp_flags & INP_DROPPED) != 0"));
245
246 if (V_nolocaltimewait) {
247 #ifdef INET6
248 if (isipv6)
249 local = in6_localaddr(&inp->in6p_faddr);
250 else
251 #endif
252 #ifdef INET
253 local = in_localip(inp->inp_faddr);
254 #else
255 local = false;
256 #endif
257 } else
258 local = false;
259
260 /*
261 * For use only by DTrace. We do not reference the state
262 * after this point so modifying it in place is not a problem.
263 */
264 tcp_state_change(tp, TCPS_TIME_WAIT);
265
266 if (local)
267 tw = &twlocal;
268 else
269 tw = uma_zalloc(V_tcptw_zone, M_NOWAIT);
270 if (tw == NULL) {
271 /*
272 * Reached limit on total number of TIMEWAIT connections
273 * allowed. Remove a connection from TIMEWAIT queue in LRU
274 * fashion to make room for this connection.
275 *
276 * XXX: Check if it possible to always have enough room
277 * in advance based on guarantees provided by uma_zalloc().
278 */
279 tw = tcp_tw_2msl_scan(1);
280 if (tw == NULL) {
281 tp = tcp_close(tp);
282 if (tp != NULL)
283 INP_WUNLOCK(inp);
284 return;
285 }
286 }
287 /*
288 * For !local case the tcptw will hold a reference on its inpcb
289 * until tcp_twclose is called.
290 */
291 tw->tw_inpcb = inp;
292
293 /*
294 * Recover last window size sent.
295 */
296 so = inp->inp_socket;
297 recwin = lmin(lmax(sbspace(&so->so_rcv), 0),
298 (long)TCP_MAXWIN << tp->rcv_scale);
299 if (recwin < (so->so_rcv.sb_hiwat / 4) &&
300 recwin < tp->t_maxseg)
301 recwin = 0;
302 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt) &&
303 recwin < (tp->rcv_adv - tp->rcv_nxt))
304 recwin = (tp->rcv_adv - tp->rcv_nxt);
305 tw->last_win = htons((u_short)(recwin >> tp->rcv_scale));
306
307 /*
308 * Set t_recent if timestamps are used on the connection.
309 */
310 if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) ==
311 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) {
312 tw->t_recent = tp->ts_recent;
313 tw->ts_offset = tp->ts_offset;
314 } else {
315 tw->t_recent = 0;
316 tw->ts_offset = 0;
317 }
318
319 tw->snd_nxt = tp->snd_nxt;
320 tw->rcv_nxt = tp->rcv_nxt;
321 tw->iss = tp->iss;
322 tw->irs = tp->irs;
323 tw->t_starttime = tp->t_starttime;
324 tw->tw_time = 0;
325
326 /* XXX
327 * If this code will
328 * be used for fin-wait-2 state also, then we may need
329 * a ts_recent from the last segment.
330 */
331 acknow = tp->t_flags & TF_ACKNOW;
332
333 /*
334 * First, discard tcpcb state, which includes stopping its timers and
335 * freeing it. tcp_discardcb() used to also release the inpcb, but
336 * that work is now done in the caller.
337 *
338 * Note: soisdisconnected() call used to be made in tcp_discardcb(),
339 * and might not be needed here any longer.
340 */
341 tcp_discardcb(tp);
342 soisdisconnected(so);
343 tw->tw_so_options = so->so_options;
344 inp->inp_flags |= INP_TIMEWAIT;
345 if (acknow)
346 tcp_twrespond(tw, TH_ACK);
347 if (local)
348 in_pcbdrop(inp);
349 else {
350 in_pcbref(inp); /* Reference from tw */
351 tw->tw_cred = crhold(so->so_cred);
352 inp->inp_ppcb = tw;
353 TCPSTATES_INC(TCPS_TIME_WAIT);
354 tcp_tw_2msl_reset(tw, 0);
355 }
356
357 /*
358 * If the inpcb owns the sole reference to the socket, then we can
359 * detach and free the socket as it is not needed in time wait.
360 */
361 if (inp->inp_flags & INP_SOCKREF) {
362 KASSERT(so->so_state & SS_PROTOREF,
363 ("tcp_twstart: !SS_PROTOREF"));
364 inp->inp_flags &= ~INP_SOCKREF;
365 INP_WUNLOCK(inp);
366 SOCK_LOCK(so);
367 so->so_state &= ~SS_PROTOREF;
368 sofree(so);
369 } else
370 INP_WUNLOCK(inp);
371 }
372
373 /*
374 * Returns 1 if the TIME_WAIT state was killed and we should start over,
375 * looking for a pcb in the listen state. Returns 0 otherwise.
376 */
377 int
378 tcp_twcheck(struct inpcb *inp, struct tcpopt *to __unused, struct tcphdr *th,
379 struct mbuf *m, int tlen)
380 {
381 struct tcptw *tw;
382 int thflags;
383 tcp_seq seq;
384
385 INP_INFO_RLOCK_ASSERT(&V_tcbinfo);
386 INP_WLOCK_ASSERT(inp);
387
388 /*
389 * XXXRW: Time wait state for inpcb has been recycled, but inpcb is
390 * still present. This is undesirable, but temporarily necessary
391 * until we work out how to handle inpcb's who's timewait state has
392 * been removed.
393 */
394 tw = intotw(inp);
395 if (tw == NULL)
396 goto drop;
397
398 thflags = th->th_flags;
399
400 /*
401 * NOTE: for FIN_WAIT_2 (to be added later),
402 * must validate sequence number before accepting RST
403 */
404
405 /*
406 * If the segment contains RST:
407 * Drop the segment - see Stevens, vol. 2, p. 964 and
408 * RFC 1337.
409 */
410 if (thflags & TH_RST)
411 goto drop;
412
413 #if 0
414 /* PAWS not needed at the moment */
415 /*
416 * RFC 1323 PAWS: If we have a timestamp reply on this segment
417 * and it's less than ts_recent, drop it.
418 */
419 if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent &&
420 TSTMP_LT(to.to_tsval, tp->ts_recent)) {
421 if ((thflags & TH_ACK) == 0)
422 goto drop;
423 goto ack;
424 }
425 /*
426 * ts_recent is never updated because we never accept new segments.
427 */
428 #endif
429
430 /*
431 * If a new connection request is received
432 * while in TIME_WAIT, drop the old connection
433 * and start over if the sequence numbers
434 * are above the previous ones.
435 */
436 if ((thflags & TH_SYN) && SEQ_GT(th->th_seq, tw->rcv_nxt)) {
437 tcp_twclose(tw, 0);
438 return (1);
439 }
440
441 /*
442 * Drop the segment if it does not contain an ACK.
443 */
444 if ((thflags & TH_ACK) == 0)
445 goto drop;
446
447 /*
448 * Reset the 2MSL timer if this is a duplicate FIN.
449 */
450 if (thflags & TH_FIN) {
451 seq = th->th_seq + tlen + (thflags & TH_SYN ? 1 : 0);
452 if (seq + 1 == tw->rcv_nxt)
453 tcp_tw_2msl_reset(tw, 1);
454 }
455
456 /*
457 * Acknowledge the segment if it has data or is not a duplicate ACK.
458 */
459 if (thflags != TH_ACK || tlen != 0 ||
460 th->th_seq != tw->rcv_nxt || th->th_ack != tw->snd_nxt) {
461 TCP_PROBE5(receive, NULL, NULL, m, NULL, th);
462 tcp_twrespond(tw, TH_ACK);
463 goto dropnoprobe;
464 }
465 drop:
466 TCP_PROBE5(receive, NULL, NULL, m, NULL, th);
467 dropnoprobe:
468 INP_WUNLOCK(inp);
469 m_freem(m);
470 return (0);
471 }
472
473 void
474 tcp_twclose(struct tcptw *tw, int reuse)
475 {
476 struct socket *so;
477 struct inpcb *inp;
478
479 /*
480 * At this point, we are in one of two situations:
481 *
482 * (1) We have no socket, just an inpcb<->twtcp pair. We can free
483 * all state.
484 *
485 * (2) We have a socket -- if we own a reference, release it and
486 * notify the socket layer.
487 */
488 inp = tw->tw_inpcb;
489 KASSERT((inp->inp_flags & INP_TIMEWAIT), ("tcp_twclose: !timewait"));
490 KASSERT(intotw(inp) == tw, ("tcp_twclose: inp_ppcb != tw"));
491 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); /* in_pcbfree() */
492 INP_WLOCK_ASSERT(inp);
493
494 tcp_tw_2msl_stop(tw, reuse);
495 inp->inp_ppcb = NULL;
496 in_pcbdrop(inp);
497
498 so = inp->inp_socket;
499 if (so != NULL) {
500 /*
501 * If there's a socket, handle two cases: first, we own a
502 * strong reference, which we will now release, or we don't
503 * in which case another reference exists (XXXRW: think
504 * about this more), and we don't need to take action.
505 */
506 if (inp->inp_flags & INP_SOCKREF) {
507 inp->inp_flags &= ~INP_SOCKREF;
508 INP_WUNLOCK(inp);
509 SOCK_LOCK(so);
510 KASSERT(so->so_state & SS_PROTOREF,
511 ("tcp_twclose: INP_SOCKREF && !SS_PROTOREF"));
512 so->so_state &= ~SS_PROTOREF;
513 sofree(so);
514 } else {
515 /*
516 * If we don't own the only reference, the socket and
517 * inpcb need to be left around to be handled by
518 * tcp_usr_detach() later.
519 */
520 INP_WUNLOCK(inp);
521 }
522 } else {
523 /*
524 * The socket has been already cleaned-up for us, only free the
525 * inpcb.
526 */
527 in_pcbfree(inp);
528 }
529 TCPSTAT_INC(tcps_closed);
530 }
531
532 static int
533 tcp_twrespond(struct tcptw *tw, int flags)
534 {
535 struct inpcb *inp = tw->tw_inpcb;
536 #if defined(INET6) || defined(INET)
537 struct tcphdr *th = NULL;
538 #endif
539 struct mbuf *m;
540 #ifdef INET
541 struct ip *ip = NULL;
542 #endif
543 u_int hdrlen, optlen;
544 int error = 0; /* Keep compiler happy */
545 struct tcpopt to;
546 #ifdef INET6
547 struct ip6_hdr *ip6 = NULL;
548 int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6;
549 #endif
550 hdrlen = 0; /* Keep compiler happy */
551
552 INP_WLOCK_ASSERT(inp);
553
554 m = m_gethdr(M_NOWAIT, MT_DATA);
555 if (m == NULL)
556 return (ENOBUFS);
557 m->m_data += max_linkhdr;
558
559 #ifdef MAC
560 mac_inpcb_create_mbuf(inp, m);
561 #endif
562
563 #ifdef INET6
564 if (isipv6) {
565 hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
566 ip6 = mtod(m, struct ip6_hdr *);
567 th = (struct tcphdr *)(ip6 + 1);
568 tcpip_fillheaders(inp, ip6, th);
569 }
570 #endif
571 #if defined(INET6) && defined(INET)
572 else
573 #endif
574 #ifdef INET
575 {
576 hdrlen = sizeof(struct tcpiphdr);
577 ip = mtod(m, struct ip *);
578 th = (struct tcphdr *)(ip + 1);
579 tcpip_fillheaders(inp, ip, th);
580 }
581 #endif
582 to.to_flags = 0;
583
584 /*
585 * Send a timestamp and echo-reply if both our side and our peer
586 * have sent timestamps in our SYN's and this is not a RST.
587 */
588 if (tw->t_recent && flags == TH_ACK) {
589 to.to_flags |= TOF_TS;
590 to.to_tsval = tcp_ts_getticks() + tw->ts_offset;
591 to.to_tsecr = tw->t_recent;
592 }
593 optlen = tcp_addoptions(&to, (u_char *)(th + 1));
594
595 m->m_len = hdrlen + optlen;
596 m->m_pkthdr.len = m->m_len;
597
598 KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small"));
599
600 th->th_seq = htonl(tw->snd_nxt);
601 th->th_ack = htonl(tw->rcv_nxt);
602 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2;
603 th->th_flags = flags;
604 th->th_win = htons(tw->last_win);
605
606 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
607 #ifdef INET6
608 if (isipv6) {
609 m->m_pkthdr.csum_flags = CSUM_TCP_IPV6;
610 th->th_sum = in6_cksum_pseudo(ip6,
611 sizeof(struct tcphdr) + optlen, IPPROTO_TCP, 0);
612 ip6->ip6_hlim = in6_selecthlim(inp, NULL);
613 TCP_PROBE5(send, NULL, NULL, ip6, NULL, th);
614 error = ip6_output(m, inp->in6p_outputopts, NULL,
615 (tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp);
616 }
617 #endif
618 #if defined(INET6) && defined(INET)
619 else
620 #endif
621 #ifdef INET
622 {
623 m->m_pkthdr.csum_flags = CSUM_TCP;
624 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
625 htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP));
626 ip->ip_len = htons(m->m_pkthdr.len);
627 if (V_path_mtu_discovery)
628 ip->ip_off |= htons(IP_DF);
629 TCP_PROBE5(send, NULL, NULL, ip, NULL, th);
630 error = ip_output(m, inp->inp_options, NULL,
631 ((tw->tw_so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0),
632 NULL, inp);
633 }
634 #endif
635 if (flags & TH_ACK)
636 TCPSTAT_INC(tcps_sndacks);
637 else
638 TCPSTAT_INC(tcps_sndctrl);
639 TCPSTAT_INC(tcps_sndtotal);
640 return (error);
641 }
642
643 static void
644 tcp_tw_2msl_reset(struct tcptw *tw, int rearm)
645 {
646
647 INP_INFO_RLOCK_ASSERT(&V_tcbinfo);
648 INP_WLOCK_ASSERT(tw->tw_inpcb);
649
650 TW_WLOCK(V_tw_lock);
651 if (rearm)
652 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl);
653 tw->tw_time = ticks + 2 * tcp_msl;
654 TAILQ_INSERT_TAIL(&V_twq_2msl, tw, tw_2msl);
655 TW_WUNLOCK(V_tw_lock);
656 }
657
658 static void
659 tcp_tw_2msl_stop(struct tcptw *tw, int reuse)
660 {
661 struct ucred *cred;
662 struct inpcb *inp;
663 int released __unused;
664
665 INP_INFO_RLOCK_ASSERT(&V_tcbinfo);
666
667 TW_WLOCK(V_tw_lock);
668 inp = tw->tw_inpcb;
669 tw->tw_inpcb = NULL;
670
671 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl);
672 cred = tw->tw_cred;
673 tw->tw_cred = NULL;
674 TW_WUNLOCK(V_tw_lock);
675
676 if (cred != NULL)
677 crfree(cred);
678
679 released = in_pcbrele_wlocked(inp);
680 KASSERT(!released, ("%s: inp should not be released here", __func__));
681
682 if (!reuse)
683 uma_zfree(V_tcptw_zone, tw);
684 TCPSTATES_DEC(TCPS_TIME_WAIT);
685 }
686
687 struct tcptw *
688 tcp_tw_2msl_scan(int reuse)
689 {
690 struct tcptw *tw;
691 struct inpcb *inp;
692 struct epoch_tracker et;
693
694 #ifdef INVARIANTS
695 if (reuse) {
696 /*
697 * Exclusive pcbinfo lock is not required in reuse case even if
698 * two inpcb locks can be acquired simultaneously:
699 * - the inpcb transitioning to TIME_WAIT state in
700 * tcp_tw_start(),
701 * - the inpcb closed by tcp_twclose().
702 *
703 * It is because only inpcbs in FIN_WAIT2 or CLOSING states can
704 * transition in TIME_WAIT state. Then a pcbcb cannot be in
705 * TIME_WAIT list and transitioning to TIME_WAIT state at same
706 * time.
707 */
708 INP_INFO_RLOCK_ASSERT(&V_tcbinfo);
709 }
710 #endif
711
712 for (;;) {
713 TW_RLOCK(V_tw_lock);
714 tw = TAILQ_FIRST(&V_twq_2msl);
715 if (tw == NULL || (!reuse && (tw->tw_time - ticks) > 0)) {
716 TW_RUNLOCK(V_tw_lock);
717 break;
718 }
719 KASSERT(tw->tw_inpcb != NULL, ("%s: tw->tw_inpcb == NULL",
720 __func__));
721
722 inp = tw->tw_inpcb;
723 in_pcbref(inp);
724 TW_RUNLOCK(V_tw_lock);
725
726 INP_INFO_RLOCK_ET(&V_tcbinfo, et);
727 INP_WLOCK(inp);
728 tw = intotw(inp);
729 if (in_pcbrele_wlocked(inp)) {
730 if (__predict_true(tw == NULL)) {
731 INP_INFO_RUNLOCK_ET(&V_tcbinfo, et);
732 continue;
733 } else {
734 /* This should not happen as in TIMEWAIT
735 * state the inp should not be destroyed
736 * before its tcptw. If INVARIANTS is
737 * defined panic.
738 */
739 #ifdef INVARIANTS
740 panic("%s: Panic before an infinite "
741 "loop: INP_TIMEWAIT && (INP_FREED "
742 "|| inp last reference) && tw != "
743 "NULL", __func__);
744 #else
745 log(LOG_ERR, "%s: Avoid an infinite "
746 "loop: INP_TIMEWAIT && (INP_FREED "
747 "|| inp last reference) && tw != "
748 "NULL", __func__);
749 #endif
750 INP_INFO_RUNLOCK_ET(&V_tcbinfo, et);
751 break;
752 }
753 }
754
755 if (tw == NULL) {
756 /* tcp_twclose() has already been called */
757 INP_WUNLOCK(inp);
758 INP_INFO_RUNLOCK_ET(&V_tcbinfo, et);
759 continue;
760 }
761
762 tcp_twclose(tw, reuse);
763 INP_INFO_RUNLOCK_ET(&V_tcbinfo, et);
764 if (reuse)
765 return tw;
766 }
767
768 return NULL;
769 }
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