1 /*-
2 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995
3 * The Regents of the University of California. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 4. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * @(#)tcp_subr.c 8.2 (Berkeley) 5/24/95
30 */
31
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD: stable/10/sys/netinet/tcp_timewait.c 309108 2016-11-24 14:48:46Z jch $");
34
35 #include "opt_inet.h"
36 #include "opt_inet6.h"
37 #include "opt_tcpdebug.h"
38
39 #include <sys/param.h>
40 #include <sys/systm.h>
41 #include <sys/callout.h>
42 #include <sys/kernel.h>
43 #include <sys/sysctl.h>
44 #include <sys/malloc.h>
45 #include <sys/mbuf.h>
46 #include <sys/priv.h>
47 #include <sys/proc.h>
48 #include <sys/socket.h>
49 #include <sys/socketvar.h>
50 #include <sys/protosw.h>
51 #include <sys/random.h>
52
53 #include <vm/uma.h>
54
55 #include <net/route.h>
56 #include <net/if.h>
57 #include <net/vnet.h>
58
59 #include <netinet/in.h>
60 #include <netinet/in_pcb.h>
61 #include <netinet/in_systm.h>
62 #include <netinet/in_var.h>
63 #include <netinet/ip.h>
64 #include <netinet/ip_icmp.h>
65 #include <netinet/ip_var.h>
66 #ifdef INET6
67 #include <netinet/ip6.h>
68 #include <netinet6/in6_pcb.h>
69 #include <netinet6/ip6_var.h>
70 #include <netinet6/scope6_var.h>
71 #include <netinet6/nd6.h>
72 #endif
73 #include <netinet/tcp.h>
74 #include <netinet/tcp_fsm.h>
75 #include <netinet/tcp_seq.h>
76 #include <netinet/tcp_timer.h>
77 #include <netinet/tcp_var.h>
78 #ifdef INET6
79 #include <netinet6/tcp6_var.h>
80 #endif
81 #include <netinet/tcpip.h>
82 #ifdef TCPDEBUG
83 #include <netinet/tcp_debug.h>
84 #endif
85 #ifdef INET6
86 #include <netinet6/ip6protosw.h>
87 #endif
88
89 #include <machine/in_cksum.h>
90
91 #include <security/mac/mac_framework.h>
92
93 static VNET_DEFINE(uma_zone_t, tcptw_zone);
94 #define V_tcptw_zone VNET(tcptw_zone)
95 static int maxtcptw;
96
97 /*
98 * The timed wait queue contains references to each of the TCP sessions
99 * currently in the TIME_WAIT state. The queue pointers, including the
100 * queue pointers in each tcptw structure, are protected using the global
101 * timewait lock, which must be held over queue iteration and modification.
102 *
103 * Rules on tcptw usage:
104 * - a inpcb is always freed _after_ its tcptw
105 * - a tcptw relies on its inpcb reference counting for memory stability
106 * - a tcptw is dereferenceable only while its inpcb is locked
107 */
108 static VNET_DEFINE(TAILQ_HEAD(, tcptw), twq_2msl);
109 #define V_twq_2msl VNET(twq_2msl)
110
111 /* Global timewait lock */
112 static VNET_DEFINE(struct rwlock, tw_lock);
113 #define V_tw_lock VNET(tw_lock)
114
115 #define TW_LOCK_INIT(tw, d) rw_init_flags(&(tw), (d), 0)
116 #define TW_LOCK_DESTROY(tw) rw_destroy(&(tw))
117 #define TW_RLOCK(tw) rw_rlock(&(tw))
118 #define TW_WLOCK(tw) rw_wlock(&(tw))
119 #define TW_RUNLOCK(tw) rw_runlock(&(tw))
120 #define TW_WUNLOCK(tw) rw_wunlock(&(tw))
121 #define TW_LOCK_ASSERT(tw) rw_assert(&(tw), RA_LOCKED)
122 #define TW_RLOCK_ASSERT(tw) rw_assert(&(tw), RA_RLOCKED)
123 #define TW_WLOCK_ASSERT(tw) rw_assert(&(tw), RA_WLOCKED)
124 #define TW_UNLOCK_ASSERT(tw) rw_assert(&(tw), RA_UNLOCKED)
125
126 static void tcp_tw_2msl_reset(struct tcptw *, int);
127 static void tcp_tw_2msl_stop(struct tcptw *, int);
128 static int tcp_twrespond(struct tcptw *, int);
129
130 static int
tcptw_auto_size(void)131 tcptw_auto_size(void)
132 {
133 int halfrange;
134
135 /*
136 * Max out at half the ephemeral port range so that TIME_WAIT
137 * sockets don't tie up too many ephemeral ports.
138 */
139 if (V_ipport_lastauto > V_ipport_firstauto)
140 halfrange = (V_ipport_lastauto - V_ipport_firstauto) / 2;
141 else
142 halfrange = (V_ipport_firstauto - V_ipport_lastauto) / 2;
143 /* Protect against goofy port ranges smaller than 32. */
144 return (imin(imax(halfrange, 32), maxsockets / 5));
145 }
146
147 static int
sysctl_maxtcptw(SYSCTL_HANDLER_ARGS)148 sysctl_maxtcptw(SYSCTL_HANDLER_ARGS)
149 {
150 int error, new;
151
152 if (maxtcptw == 0)
153 new = tcptw_auto_size();
154 else
155 new = maxtcptw;
156 error = sysctl_handle_int(oidp, &new, 0, req);
157 if (error == 0 && req->newptr)
158 if (new >= 32) {
159 maxtcptw = new;
160 uma_zone_set_max(V_tcptw_zone, maxtcptw);
161 }
162 return (error);
163 }
164
165 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, maxtcptw, CTLTYPE_INT|CTLFLAG_RW,
166 &maxtcptw, 0, sysctl_maxtcptw, "IU",
167 "Maximum number of compressed TCP TIME_WAIT entries");
168
169 VNET_DEFINE(int, nolocaltimewait) = 0;
170 #define V_nolocaltimewait VNET(nolocaltimewait)
171 SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, nolocaltimewait, CTLFLAG_RW,
172 &VNET_NAME(nolocaltimewait), 0,
173 "Do not create compressed TCP TIME_WAIT entries for local connections");
174
175 void
tcp_tw_zone_change(void)176 tcp_tw_zone_change(void)
177 {
178
179 if (maxtcptw == 0)
180 uma_zone_set_max(V_tcptw_zone, tcptw_auto_size());
181 }
182
183 void
tcp_tw_init(void)184 tcp_tw_init(void)
185 {
186
187 V_tcptw_zone = uma_zcreate("tcptw", sizeof(struct tcptw),
188 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
189 TUNABLE_INT_FETCH("net.inet.tcp.maxtcptw", &maxtcptw);
190 if (maxtcptw == 0)
191 uma_zone_set_max(V_tcptw_zone, tcptw_auto_size());
192 else
193 uma_zone_set_max(V_tcptw_zone, maxtcptw);
194 TAILQ_INIT(&V_twq_2msl);
195 TW_LOCK_INIT(V_tw_lock, "tcptw");
196 }
197
198 #ifdef VIMAGE
199 void
tcp_tw_destroy(void)200 tcp_tw_destroy(void)
201 {
202 struct tcptw *tw;
203
204 INP_INFO_RLOCK(&V_tcbinfo);
205 while ((tw = TAILQ_FIRST(&V_twq_2msl)) != NULL)
206 tcp_twclose(tw, 0);
207 INP_INFO_RUNLOCK(&V_tcbinfo);
208
209 TW_LOCK_DESTROY(V_tw_lock);
210 uma_zdestroy(V_tcptw_zone);
211 }
212 #endif
213
214 /*
215 * Move a TCP connection into TIME_WAIT state.
216 * tcbinfo is locked.
217 * inp is locked, and is unlocked before returning.
218 */
219 void
tcp_twstart(struct tcpcb * tp)220 tcp_twstart(struct tcpcb *tp)
221 {
222 struct tcptw *tw;
223 struct inpcb *inp = tp->t_inpcb;
224 int acknow;
225 struct socket *so;
226 #ifdef INET6
227 int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6;
228 #endif
229
230 INP_INFO_RLOCK_ASSERT(&V_tcbinfo);
231 INP_WLOCK_ASSERT(inp);
232
233 /* A dropped inp should never transition to TIME_WAIT state. */
234 KASSERT((inp->inp_flags & INP_DROPPED) == 0, ("tcp_twstart: "
235 "(inp->inp_flags & INP_DROPPED) != 0"));
236
237 if (V_nolocaltimewait) {
238 int error = 0;
239 #ifdef INET6
240 if (isipv6)
241 error = in6_localaddr(&inp->in6p_faddr);
242 #endif
243 #if defined(INET6) && defined(INET)
244 else
245 #endif
246 #ifdef INET
247 error = in_localip(inp->inp_faddr);
248 #endif
249 if (error) {
250 tp = tcp_close(tp);
251 if (tp != NULL)
252 INP_WUNLOCK(inp);
253 return;
254 }
255 }
256
257
258 /*
259 * For use only by DTrace. We do not reference the state
260 * after this point so modifying it in place is not a problem.
261 */
262 tcp_state_change(tp, TCPS_TIME_WAIT);
263
264 tw = uma_zalloc(V_tcptw_zone, M_NOWAIT);
265 if (tw == NULL) {
266 /*
267 * Reached limit on total number of TIMEWAIT connections
268 * allowed. Remove a connection from TIMEWAIT queue in LRU
269 * fashion to make room for this connection.
270 *
271 * XXX: Check if it possible to always have enough room
272 * in advance based on guarantees provided by uma_zalloc().
273 */
274 tw = tcp_tw_2msl_scan(1);
275 if (tw == NULL) {
276 tp = tcp_close(tp);
277 if (tp != NULL)
278 INP_WUNLOCK(inp);
279 return;
280 }
281 }
282 /*
283 * The tcptw will hold a reference on its inpcb until tcp_twclose
284 * is called
285 */
286 tw->tw_inpcb = inp;
287 in_pcbref(inp); /* Reference from tw */
288
289 /*
290 * Recover last window size sent.
291 */
292 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt))
293 tw->last_win = (tp->rcv_adv - tp->rcv_nxt) >> tp->rcv_scale;
294 else
295 tw->last_win = 0;
296
297 /*
298 * Set t_recent if timestamps are used on the connection.
299 */
300 if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) ==
301 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) {
302 tw->t_recent = tp->ts_recent;
303 tw->ts_offset = tp->ts_offset;
304 } else {
305 tw->t_recent = 0;
306 tw->ts_offset = 0;
307 }
308
309 tw->snd_nxt = tp->snd_nxt;
310 tw->rcv_nxt = tp->rcv_nxt;
311 tw->iss = tp->iss;
312 tw->irs = tp->irs;
313 tw->t_starttime = tp->t_starttime;
314 tw->tw_time = 0;
315
316 /* XXX
317 * If this code will
318 * be used for fin-wait-2 state also, then we may need
319 * a ts_recent from the last segment.
320 */
321 acknow = tp->t_flags & TF_ACKNOW;
322
323 /*
324 * First, discard tcpcb state, which includes stopping its timers and
325 * freeing it. tcp_discardcb() used to also release the inpcb, but
326 * that work is now done in the caller.
327 *
328 * Note: soisdisconnected() call used to be made in tcp_discardcb(),
329 * and might not be needed here any longer.
330 */
331 tcp_discardcb(tp);
332 so = inp->inp_socket;
333 soisdisconnected(so);
334 tw->tw_cred = crhold(so->so_cred);
335 SOCK_LOCK(so);
336 tw->tw_so_options = so->so_options;
337 SOCK_UNLOCK(so);
338 if (acknow)
339 tcp_twrespond(tw, TH_ACK);
340 inp->inp_ppcb = tw;
341 inp->inp_flags |= INP_TIMEWAIT;
342 tcp_tw_2msl_reset(tw, 0);
343
344 /*
345 * If the inpcb owns the sole reference to the socket, then we can
346 * detach and free the socket as it is not needed in time wait.
347 */
348 if (inp->inp_flags & INP_SOCKREF) {
349 KASSERT(so->so_state & SS_PROTOREF,
350 ("tcp_twstart: !SS_PROTOREF"));
351 inp->inp_flags &= ~INP_SOCKREF;
352 INP_WUNLOCK(inp);
353 ACCEPT_LOCK();
354 SOCK_LOCK(so);
355 so->so_state &= ~SS_PROTOREF;
356 sofree(so);
357 } else
358 INP_WUNLOCK(inp);
359 }
360
361 #if 0
362 /*
363 * The appromixate rate of ISN increase of Microsoft TCP stacks;
364 * the actual rate is slightly higher due to the addition of
365 * random positive increments.
366 *
367 * Most other new OSes use semi-randomized ISN values, so we
368 * do not need to worry about them.
369 */
370 #define MS_ISN_BYTES_PER_SECOND 250000
371
372 /*
373 * Determine if the ISN we will generate has advanced beyond the last
374 * sequence number used by the previous connection. If so, indicate
375 * that it is safe to recycle this tw socket by returning 1.
376 */
377 int
378 tcp_twrecycleable(struct tcptw *tw)
379 {
380 tcp_seq new_iss = tw->iss;
381 tcp_seq new_irs = tw->irs;
382
383 INP_INFO_RLOCK_ASSERT(&V_tcbinfo);
384 new_iss += (ticks - tw->t_starttime) * (ISN_BYTES_PER_SECOND / hz);
385 new_irs += (ticks - tw->t_starttime) * (MS_ISN_BYTES_PER_SECOND / hz);
386
387 if (SEQ_GT(new_iss, tw->snd_nxt) && SEQ_GT(new_irs, tw->rcv_nxt))
388 return (1);
389 else
390 return (0);
391 }
392 #endif
393
394 /*
395 * Returns 1 if the TIME_WAIT state was killed and we should start over,
396 * looking for a pcb in the listen state. Returns 0 otherwise.
397 */
398 int
tcp_twcheck(struct inpcb * inp,struct tcpopt * to __unused,struct tcphdr * th,struct mbuf * m,int tlen)399 tcp_twcheck(struct inpcb *inp, struct tcpopt *to __unused, struct tcphdr *th,
400 struct mbuf *m, int tlen)
401 {
402 struct tcptw *tw;
403 int thflags;
404 tcp_seq seq;
405
406 INP_INFO_RLOCK_ASSERT(&V_tcbinfo);
407 INP_WLOCK_ASSERT(inp);
408
409 /*
410 * XXXRW: Time wait state for inpcb has been recycled, but inpcb is
411 * still present. This is undesirable, but temporarily necessary
412 * until we work out how to handle inpcb's who's timewait state has
413 * been removed.
414 */
415 tw = intotw(inp);
416 if (tw == NULL)
417 goto drop;
418
419 thflags = th->th_flags;
420
421 /*
422 * NOTE: for FIN_WAIT_2 (to be added later),
423 * must validate sequence number before accepting RST
424 */
425
426 /*
427 * If the segment contains RST:
428 * Drop the segment - see Stevens, vol. 2, p. 964 and
429 * RFC 1337.
430 */
431 if (thflags & TH_RST)
432 goto drop;
433
434 #if 0
435 /* PAWS not needed at the moment */
436 /*
437 * RFC 1323 PAWS: If we have a timestamp reply on this segment
438 * and it's less than ts_recent, drop it.
439 */
440 if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent &&
441 TSTMP_LT(to.to_tsval, tp->ts_recent)) {
442 if ((thflags & TH_ACK) == 0)
443 goto drop;
444 goto ack;
445 }
446 /*
447 * ts_recent is never updated because we never accept new segments.
448 */
449 #endif
450
451 /*
452 * If a new connection request is received
453 * while in TIME_WAIT, drop the old connection
454 * and start over if the sequence numbers
455 * are above the previous ones.
456 */
457 if ((thflags & TH_SYN) && SEQ_GT(th->th_seq, tw->rcv_nxt)) {
458 tcp_twclose(tw, 0);
459 return (1);
460 }
461
462 /*
463 * Drop the segment if it does not contain an ACK.
464 */
465 if ((thflags & TH_ACK) == 0)
466 goto drop;
467
468 /*
469 * Reset the 2MSL timer if this is a duplicate FIN.
470 */
471 if (thflags & TH_FIN) {
472 seq = th->th_seq + tlen + (thflags & TH_SYN ? 1 : 0);
473 if (seq + 1 == tw->rcv_nxt)
474 tcp_tw_2msl_reset(tw, 1);
475 }
476
477 /*
478 * Acknowledge the segment if it has data or is not a duplicate ACK.
479 */
480 if (thflags != TH_ACK || tlen != 0 ||
481 th->th_seq != tw->rcv_nxt || th->th_ack != tw->snd_nxt)
482 tcp_twrespond(tw, TH_ACK);
483 drop:
484 INP_WUNLOCK(inp);
485 m_freem(m);
486 return (0);
487 }
488
489 void
tcp_twclose(struct tcptw * tw,int reuse)490 tcp_twclose(struct tcptw *tw, int reuse)
491 {
492 struct socket *so;
493 struct inpcb *inp;
494
495 /*
496 * At this point, we are in one of two situations:
497 *
498 * (1) We have no socket, just an inpcb<->twtcp pair. We can free
499 * all state.
500 *
501 * (2) We have a socket -- if we own a reference, release it and
502 * notify the socket layer.
503 */
504 inp = tw->tw_inpcb;
505 KASSERT((inp->inp_flags & INP_TIMEWAIT), ("tcp_twclose: !timewait"));
506 KASSERT(intotw(inp) == tw, ("tcp_twclose: inp_ppcb != tw"));
507 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); /* in_pcbfree() */
508 INP_WLOCK_ASSERT(inp);
509
510 tcp_tw_2msl_stop(tw, reuse);
511 inp->inp_ppcb = NULL;
512 in_pcbdrop(inp);
513
514 so = inp->inp_socket;
515 if (so != NULL) {
516 /*
517 * If there's a socket, handle two cases: first, we own a
518 * strong reference, which we will now release, or we don't
519 * in which case another reference exists (XXXRW: think
520 * about this more), and we don't need to take action.
521 */
522 if (inp->inp_flags & INP_SOCKREF) {
523 inp->inp_flags &= ~INP_SOCKREF;
524 INP_WUNLOCK(inp);
525 ACCEPT_LOCK();
526 SOCK_LOCK(so);
527 KASSERT(so->so_state & SS_PROTOREF,
528 ("tcp_twclose: INP_SOCKREF && !SS_PROTOREF"));
529 so->so_state &= ~SS_PROTOREF;
530 sofree(so);
531 } else {
532 /*
533 * If we don't own the only reference, the socket and
534 * inpcb need to be left around to be handled by
535 * tcp_usr_detach() later.
536 */
537 INP_WUNLOCK(inp);
538 }
539 } else {
540 /*
541 * The socket has been already cleaned-up for us, only free the
542 * inpcb.
543 */
544 in_pcbfree(inp);
545 }
546 TCPSTAT_INC(tcps_closed);
547 }
548
549 static int
tcp_twrespond(struct tcptw * tw,int flags)550 tcp_twrespond(struct tcptw *tw, int flags)
551 {
552 struct inpcb *inp = tw->tw_inpcb;
553 #if defined(INET6) || defined(INET)
554 struct tcphdr *th = NULL;
555 #endif
556 struct mbuf *m;
557 #ifdef INET
558 struct ip *ip = NULL;
559 #endif
560 u_int hdrlen, optlen;
561 int error = 0; /* Keep compiler happy */
562 struct tcpopt to;
563 #ifdef INET6
564 struct ip6_hdr *ip6 = NULL;
565 int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6;
566 #endif
567 hdrlen = 0; /* Keep compiler happy */
568
569 INP_WLOCK_ASSERT(inp);
570
571 m = m_gethdr(M_NOWAIT, MT_DATA);
572 if (m == NULL)
573 return (ENOBUFS);
574 m->m_data += max_linkhdr;
575
576 #ifdef MAC
577 mac_inpcb_create_mbuf(inp, m);
578 #endif
579
580 #ifdef INET6
581 if (isipv6) {
582 hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
583 ip6 = mtod(m, struct ip6_hdr *);
584 th = (struct tcphdr *)(ip6 + 1);
585 tcpip_fillheaders(inp, ip6, th);
586 }
587 #endif
588 #if defined(INET6) && defined(INET)
589 else
590 #endif
591 #ifdef INET
592 {
593 hdrlen = sizeof(struct tcpiphdr);
594 ip = mtod(m, struct ip *);
595 th = (struct tcphdr *)(ip + 1);
596 tcpip_fillheaders(inp, ip, th);
597 }
598 #endif
599 to.to_flags = 0;
600
601 /*
602 * Send a timestamp and echo-reply if both our side and our peer
603 * have sent timestamps in our SYN's and this is not a RST.
604 */
605 if (tw->t_recent && flags == TH_ACK) {
606 to.to_flags |= TOF_TS;
607 to.to_tsval = tcp_ts_getticks() + tw->ts_offset;
608 to.to_tsecr = tw->t_recent;
609 }
610 optlen = tcp_addoptions(&to, (u_char *)(th + 1));
611
612 m->m_len = hdrlen + optlen;
613 m->m_pkthdr.len = m->m_len;
614
615 KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small"));
616
617 th->th_seq = htonl(tw->snd_nxt);
618 th->th_ack = htonl(tw->rcv_nxt);
619 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2;
620 th->th_flags = flags;
621 th->th_win = htons(tw->last_win);
622
623 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
624 #ifdef INET6
625 if (isipv6) {
626 m->m_pkthdr.csum_flags = CSUM_TCP_IPV6;
627 th->th_sum = in6_cksum_pseudo(ip6,
628 sizeof(struct tcphdr) + optlen, IPPROTO_TCP, 0);
629 ip6->ip6_hlim = in6_selecthlim(inp, NULL);
630 error = ip6_output(m, inp->in6p_outputopts, NULL,
631 (tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp);
632 }
633 #endif
634 #if defined(INET6) && defined(INET)
635 else
636 #endif
637 #ifdef INET
638 {
639 m->m_pkthdr.csum_flags = CSUM_TCP;
640 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
641 htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP));
642 ip->ip_len = htons(m->m_pkthdr.len);
643 if (V_path_mtu_discovery)
644 ip->ip_off |= htons(IP_DF);
645 error = ip_output(m, inp->inp_options, NULL,
646 ((tw->tw_so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0),
647 NULL, inp);
648 }
649 #endif
650 if (flags & TH_ACK)
651 TCPSTAT_INC(tcps_sndacks);
652 else
653 TCPSTAT_INC(tcps_sndctrl);
654 TCPSTAT_INC(tcps_sndtotal);
655 return (error);
656 }
657
658 static void
tcp_tw_2msl_reset(struct tcptw * tw,int rearm)659 tcp_tw_2msl_reset(struct tcptw *tw, int rearm)
660 {
661
662 INP_INFO_RLOCK_ASSERT(&V_tcbinfo);
663 INP_WLOCK_ASSERT(tw->tw_inpcb);
664
665 TW_WLOCK(V_tw_lock);
666 if (rearm)
667 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl);
668 tw->tw_time = ticks + 2 * tcp_msl;
669 TAILQ_INSERT_TAIL(&V_twq_2msl, tw, tw_2msl);
670 TW_WUNLOCK(V_tw_lock);
671 }
672
673 static void
tcp_tw_2msl_stop(struct tcptw * tw,int reuse)674 tcp_tw_2msl_stop(struct tcptw *tw, int reuse)
675 {
676 struct ucred *cred;
677 struct inpcb *inp;
678 int released;
679
680 INP_INFO_RLOCK_ASSERT(&V_tcbinfo);
681
682 TW_WLOCK(V_tw_lock);
683 inp = tw->tw_inpcb;
684 tw->tw_inpcb = NULL;
685
686 TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl);
687 cred = tw->tw_cred;
688 tw->tw_cred = NULL;
689 TW_WUNLOCK(V_tw_lock);
690
691 if (cred != NULL)
692 crfree(cred);
693
694 released = in_pcbrele_wlocked(inp);
695 KASSERT(!released, ("%s: inp should not be released here", __func__));
696
697 if (!reuse)
698 uma_zfree(V_tcptw_zone, tw);
699 }
700
701 struct tcptw *
tcp_tw_2msl_scan(int reuse)702 tcp_tw_2msl_scan(int reuse)
703 {
704 struct tcptw *tw;
705 struct inpcb *inp;
706
707 #ifdef INVARIANTS
708 if (reuse) {
709 /*
710 * Exclusive pcbinfo lock is not required in reuse case even if
711 * two inpcb locks can be acquired simultaneously:
712 * - the inpcb transitioning to TIME_WAIT state in
713 * tcp_tw_start(),
714 * - the inpcb closed by tcp_twclose().
715 *
716 * It is because only inpcbs in FIN_WAIT2 or CLOSING states can
717 * transition in TIME_WAIT state. Then a pcbcb cannot be in
718 * TIME_WAIT list and transitioning to TIME_WAIT state at same
719 * time.
720 */
721 INP_INFO_RLOCK_ASSERT(&V_tcbinfo);
722 }
723 #endif
724
725 for (;;) {
726 TW_RLOCK(V_tw_lock);
727 tw = TAILQ_FIRST(&V_twq_2msl);
728 if (tw == NULL || (!reuse && (tw->tw_time - ticks) > 0)) {
729 TW_RUNLOCK(V_tw_lock);
730 break;
731 }
732 KASSERT(tw->tw_inpcb != NULL, ("%s: tw->tw_inpcb == NULL",
733 __func__));
734
735 inp = tw->tw_inpcb;
736 in_pcbref(inp);
737 TW_RUNLOCK(V_tw_lock);
738
739 if (INP_INFO_TRY_RLOCK(&V_tcbinfo)) {
740
741 INP_WLOCK(inp);
742 tw = intotw(inp);
743 if (in_pcbrele_wlocked(inp)) {
744 KASSERT(tw == NULL, ("%s: held last inp "
745 "reference but tw not NULL", __func__));
746 INP_INFO_RUNLOCK(&V_tcbinfo);
747 continue;
748 }
749
750 if (tw == NULL) {
751 /* tcp_twclose() has already been called */
752 INP_WUNLOCK(inp);
753 INP_INFO_RUNLOCK(&V_tcbinfo);
754 continue;
755 }
756
757 tcp_twclose(tw, reuse);
758 INP_INFO_RUNLOCK(&V_tcbinfo);
759 if (reuse)
760 return tw;
761 } else {
762 /* INP_INFO lock is busy, continue later. */
763 INP_WLOCK(inp);
764 if (!in_pcbrele_wlocked(inp))
765 INP_WUNLOCK(inp);
766 break;
767 }
768 }
769
770 return NULL;
771 }
772