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