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_timer.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_tcpdebug.h"
40 #include "opt_rss.h"
41
42 #include <sys/param.h>
43 #include <sys/kernel.h>
44 #include <sys/lock.h>
45 #include <sys/mbuf.h>
46 #include <sys/mutex.h>
47 #include <sys/protosw.h>
48 #include <sys/smp.h>
49 #include <sys/socket.h>
50 #include <sys/socketvar.h>
51 #include <sys/sysctl.h>
52 #include <sys/systm.h>
53
54 #include <net/if.h>
55 #include <net/route.h>
56 #include <net/rss_config.h>
57 #include <net/vnet.h>
58 #include <net/netisr.h>
59
60 #include <netinet/in.h>
61 #include <netinet/in_kdtrace.h>
62 #include <netinet/in_pcb.h>
63 #include <netinet/in_rss.h>
64 #include <netinet/in_systm.h>
65 #ifdef INET6
66 #include <netinet6/in6_pcb.h>
67 #endif
68 #include <netinet/ip_var.h>
69 #include <netinet/tcp.h>
70 #include <netinet/tcp_fsm.h>
71 #include <netinet/tcp_log_buf.h>
72 #include <netinet/tcp_timer.h>
73 #include <netinet/tcp_var.h>
74 #include <netinet/tcp_seq.h>
75 #include <netinet/cc/cc.h>
76 #ifdef INET6
77 #include <netinet6/tcp6_var.h>
78 #endif
79 #include <netinet/tcpip.h>
80 #ifdef TCPDEBUG
81 #include <netinet/tcp_debug.h>
82 #endif
83
84 int tcp_persmin;
85 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, persmin, CTLTYPE_INT|CTLFLAG_RW,
86 &tcp_persmin, 0, sysctl_msec_to_ticks, "I", "minimum persistence interval");
87
88 int tcp_persmax;
89 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, persmax, CTLTYPE_INT|CTLFLAG_RW,
90 &tcp_persmax, 0, sysctl_msec_to_ticks, "I", "maximum persistence interval");
91
92 int tcp_keepinit;
93 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINIT, keepinit, CTLTYPE_INT|CTLFLAG_RW,
94 &tcp_keepinit, 0, sysctl_msec_to_ticks, "I", "time to establish connection");
95
96 int tcp_keepidle;
97 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPIDLE, keepidle, CTLTYPE_INT|CTLFLAG_RW,
98 &tcp_keepidle, 0, sysctl_msec_to_ticks, "I", "time before keepalive probes begin");
99
100 int tcp_keepintvl;
101 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINTVL, keepintvl, CTLTYPE_INT|CTLFLAG_RW,
102 &tcp_keepintvl, 0, sysctl_msec_to_ticks, "I", "time between keepalive probes");
103
104 int tcp_delacktime;
105 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DELACKTIME, delacktime, CTLTYPE_INT|CTLFLAG_RW,
106 &tcp_delacktime, 0, sysctl_msec_to_ticks, "I",
107 "Time before a delayed ACK is sent");
108
109 int tcp_msl;
110 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, msl, CTLTYPE_INT|CTLFLAG_RW,
111 &tcp_msl, 0, sysctl_msec_to_ticks, "I", "Maximum segment lifetime");
112
113 int tcp_rexmit_initial;
114 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_initial, CTLTYPE_INT|CTLFLAG_RW,
115 &tcp_rexmit_initial, 0, sysctl_msec_to_ticks, "I",
116 "Initial Retransmission Timeout");
117
118 int tcp_rexmit_min;
119 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_min, CTLTYPE_INT|CTLFLAG_RW,
120 &tcp_rexmit_min, 0, sysctl_msec_to_ticks, "I",
121 "Minimum Retransmission Timeout");
122
123 int tcp_rexmit_slop;
124 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_slop, CTLTYPE_INT|CTLFLAG_RW,
125 &tcp_rexmit_slop, 0, sysctl_msec_to_ticks, "I",
126 "Retransmission Timer Slop");
127
128 int tcp_always_keepalive = 1;
129 SYSCTL_INT(_net_inet_tcp, OID_AUTO, always_keepalive, CTLFLAG_RW,
130 &tcp_always_keepalive , 0, "Assume SO_KEEPALIVE on all TCP connections");
131
132 int tcp_fast_finwait2_recycle = 0;
133 SYSCTL_INT(_net_inet_tcp, OID_AUTO, fast_finwait2_recycle, CTLFLAG_RW,
134 &tcp_fast_finwait2_recycle, 0,
135 "Recycle closed FIN_WAIT_2 connections faster");
136
137 int tcp_finwait2_timeout;
138 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, finwait2_timeout, CTLTYPE_INT|CTLFLAG_RW,
139 &tcp_finwait2_timeout, 0, sysctl_msec_to_ticks, "I", "FIN-WAIT2 timeout");
140
141 int tcp_keepcnt = TCPTV_KEEPCNT;
142 SYSCTL_INT(_net_inet_tcp, OID_AUTO, keepcnt, CTLFLAG_RW, &tcp_keepcnt, 0,
143 "Number of keepalive probes to send");
144
145 /* max idle probes */
146 int tcp_maxpersistidle;
147
148 int tcp_rexmit_drop_options = 0;
149 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rexmit_drop_options, CTLFLAG_RW,
150 &tcp_rexmit_drop_options, 0,
151 "Drop TCP options from 3rd and later retransmitted SYN");
152
153 VNET_DEFINE(int, tcp_pmtud_blackhole_detect);
154 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_detection,
155 CTLFLAG_RW|CTLFLAG_VNET,
156 &VNET_NAME(tcp_pmtud_blackhole_detect), 0,
157 "Path MTU Discovery Black Hole Detection Enabled");
158
159 #ifdef INET
160 VNET_DEFINE(int, tcp_pmtud_blackhole_mss) = 1200;
161 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_mss,
162 CTLFLAG_RW|CTLFLAG_VNET,
163 &VNET_NAME(tcp_pmtud_blackhole_mss), 0,
164 "Path MTU Discovery Black Hole Detection lowered MSS");
165 #endif
166
167 #ifdef INET6
168 VNET_DEFINE(int, tcp_v6pmtud_blackhole_mss) = 1220;
169 SYSCTL_INT(_net_inet_tcp, OID_AUTO, v6pmtud_blackhole_mss,
170 CTLFLAG_RW|CTLFLAG_VNET,
171 &VNET_NAME(tcp_v6pmtud_blackhole_mss), 0,
172 "Path MTU Discovery IPv6 Black Hole Detection lowered MSS");
173 #endif
174
175 #ifdef RSS
176 static int per_cpu_timers = 1;
177 #else
178 static int per_cpu_timers = 0;
179 #endif
180 SYSCTL_INT(_net_inet_tcp, OID_AUTO, per_cpu_timers, CTLFLAG_RW,
181 &per_cpu_timers , 0, "run tcp timers on all cpus");
182
183 /*
184 * Map the given inp to a CPU id.
185 *
186 * This queries RSS if it's compiled in, else it defaults to the current
187 * CPU ID.
188 */
189 inline int
inp_to_cpuid(struct inpcb * inp)190 inp_to_cpuid(struct inpcb *inp)
191 {
192 u_int cpuid;
193
194 #ifdef RSS
195 if (per_cpu_timers) {
196 cpuid = rss_hash2cpuid(inp->inp_flowid, inp->inp_flowtype);
197 if (cpuid == NETISR_CPUID_NONE)
198 return (curcpu); /* XXX */
199 else
200 return (cpuid);
201 }
202 #else
203 /* Legacy, pre-RSS behaviour */
204 if (per_cpu_timers) {
205 /*
206 * We don't have a flowid -> cpuid mapping, so cheat and
207 * just map unknown cpuids to curcpu. Not the best, but
208 * apparently better than defaulting to swi 0.
209 */
210 cpuid = inp->inp_flowid % (mp_maxid + 1);
211 if (! CPU_ABSENT(cpuid))
212 return (cpuid);
213 return (curcpu);
214 }
215 #endif
216 /* Default for RSS and non-RSS - cpuid 0 */
217 else {
218 return (0);
219 }
220 }
221
222 /*
223 * Tcp protocol timeout routine called every 500 ms.
224 * Updates timestamps used for TCP
225 * causes finite state machine actions if timers expire.
226 */
227 void
tcp_slowtimo(void)228 tcp_slowtimo(void)
229 {
230 VNET_ITERATOR_DECL(vnet_iter);
231
232 VNET_LIST_RLOCK_NOSLEEP();
233 VNET_FOREACH(vnet_iter) {
234 CURVNET_SET(vnet_iter);
235 (void) tcp_tw_2msl_scan(0);
236 CURVNET_RESTORE();
237 }
238 VNET_LIST_RUNLOCK_NOSLEEP();
239 }
240
241 int tcp_backoff[TCP_MAXRXTSHIFT + 1] =
242 { 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 512, 512, 512 };
243
244 int tcp_totbackoff = 2559; /* sum of tcp_backoff[] */
245
246 /*
247 * TCP timer processing.
248 */
249
250 void
tcp_timer_delack(void * xtp)251 tcp_timer_delack(void *xtp)
252 {
253 struct tcpcb *tp = xtp;
254 struct inpcb *inp;
255 CURVNET_SET(tp->t_vnet);
256
257 inp = tp->t_inpcb;
258 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
259 INP_WLOCK(inp);
260 if (callout_pending(&tp->t_timers->tt_delack) ||
261 !callout_active(&tp->t_timers->tt_delack)) {
262 INP_WUNLOCK(inp);
263 CURVNET_RESTORE();
264 return;
265 }
266 callout_deactivate(&tp->t_timers->tt_delack);
267 if ((inp->inp_flags & INP_DROPPED) != 0) {
268 INP_WUNLOCK(inp);
269 CURVNET_RESTORE();
270 return;
271 }
272 tp->t_flags |= TF_ACKNOW;
273 TCPSTAT_INC(tcps_delack);
274 (void) tp->t_fb->tfb_tcp_output(tp);
275 INP_WUNLOCK(inp);
276 CURVNET_RESTORE();
277 }
278
279 void
tcp_inpinfo_lock_del(struct inpcb * inp,struct tcpcb * tp)280 tcp_inpinfo_lock_del(struct inpcb *inp, struct tcpcb *tp)
281 {
282 if (inp && tp != NULL)
283 INP_WUNLOCK(inp);
284 }
285
286 void
tcp_timer_2msl(void * xtp)287 tcp_timer_2msl(void *xtp)
288 {
289 struct tcpcb *tp = xtp;
290 struct inpcb *inp;
291 struct epoch_tracker et;
292 CURVNET_SET(tp->t_vnet);
293 #ifdef TCPDEBUG
294 int ostate;
295
296 ostate = tp->t_state;
297 #endif
298 inp = tp->t_inpcb;
299 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
300 INP_WLOCK(inp);
301 tcp_free_sackholes(tp);
302 if (callout_pending(&tp->t_timers->tt_2msl) ||
303 !callout_active(&tp->t_timers->tt_2msl)) {
304 INP_WUNLOCK(tp->t_inpcb);
305 CURVNET_RESTORE();
306 return;
307 }
308 callout_deactivate(&tp->t_timers->tt_2msl);
309 if ((inp->inp_flags & INP_DROPPED) != 0) {
310 INP_WUNLOCK(inp);
311 CURVNET_RESTORE();
312 return;
313 }
314 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
315 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
316 /*
317 * 2 MSL timeout in shutdown went off. If we're closed but
318 * still waiting for peer to close and connection has been idle
319 * too long delete connection control block. Otherwise, check
320 * again in a bit.
321 *
322 * If in TIME_WAIT state just ignore as this timeout is handled in
323 * tcp_tw_2msl_scan().
324 *
325 * If fastrecycle of FIN_WAIT_2, in FIN_WAIT_2 and receiver has closed,
326 * there's no point in hanging onto FIN_WAIT_2 socket. Just close it.
327 * Ignore fact that there were recent incoming segments.
328 */
329 if ((inp->inp_flags & INP_TIMEWAIT) != 0) {
330 INP_WUNLOCK(inp);
331 CURVNET_RESTORE();
332 return;
333 }
334 if (tcp_fast_finwait2_recycle && tp->t_state == TCPS_FIN_WAIT_2 &&
335 tp->t_inpcb && tp->t_inpcb->inp_socket &&
336 (tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE)) {
337 TCPSTAT_INC(tcps_finwait2_drops);
338 if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
339 tcp_inpinfo_lock_del(inp, tp);
340 goto out;
341 }
342 INP_INFO_RLOCK_ET(&V_tcbinfo, et);
343 tp = tcp_close(tp);
344 INP_INFO_RUNLOCK_ET(&V_tcbinfo, et);
345 tcp_inpinfo_lock_del(inp, tp);
346 goto out;
347 } else {
348 if (ticks - tp->t_rcvtime <= TP_MAXIDLE(tp)) {
349 callout_reset(&tp->t_timers->tt_2msl,
350 TP_KEEPINTVL(tp), tcp_timer_2msl, tp);
351 } else {
352 if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
353 tcp_inpinfo_lock_del(inp, tp);
354 goto out;
355 }
356 INP_INFO_RLOCK_ET(&V_tcbinfo, et);
357 tp = tcp_close(tp);
358 INP_INFO_RUNLOCK_ET(&V_tcbinfo, et);
359 tcp_inpinfo_lock_del(inp, tp);
360 goto out;
361 }
362 }
363
364 #ifdef TCPDEBUG
365 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
366 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
367 PRU_SLOWTIMO);
368 #endif
369 TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
370
371 if (tp != NULL)
372 INP_WUNLOCK(inp);
373 out:
374 CURVNET_RESTORE();
375 }
376
377 void
tcp_timer_keep(void * xtp)378 tcp_timer_keep(void *xtp)
379 {
380 struct tcpcb *tp = xtp;
381 struct tcptemp *t_template;
382 struct inpcb *inp;
383 struct epoch_tracker et;
384 CURVNET_SET(tp->t_vnet);
385 #ifdef TCPDEBUG
386 int ostate;
387
388 ostate = tp->t_state;
389 #endif
390 inp = tp->t_inpcb;
391 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
392 INP_WLOCK(inp);
393 if (callout_pending(&tp->t_timers->tt_keep) ||
394 !callout_active(&tp->t_timers->tt_keep)) {
395 INP_WUNLOCK(inp);
396 CURVNET_RESTORE();
397 return;
398 }
399 callout_deactivate(&tp->t_timers->tt_keep);
400 if ((inp->inp_flags & INP_DROPPED) != 0) {
401 INP_WUNLOCK(inp);
402 CURVNET_RESTORE();
403 return;
404 }
405 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
406 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
407
408 /*
409 * Because we don't regularly reset the keepalive callout in
410 * the ESTABLISHED state, it may be that we don't actually need
411 * to send a keepalive yet. If that occurs, schedule another
412 * call for the next time the keepalive timer might expire.
413 */
414 if (TCPS_HAVEESTABLISHED(tp->t_state)) {
415 u_int idletime;
416
417 idletime = ticks - tp->t_rcvtime;
418 if (idletime < TP_KEEPIDLE(tp)) {
419 callout_reset(&tp->t_timers->tt_keep,
420 TP_KEEPIDLE(tp) - idletime, tcp_timer_keep, tp);
421 INP_WUNLOCK(inp);
422 CURVNET_RESTORE();
423 return;
424 }
425 }
426
427 /*
428 * Keep-alive timer went off; send something
429 * or drop connection if idle for too long.
430 */
431 TCPSTAT_INC(tcps_keeptimeo);
432 if (tp->t_state < TCPS_ESTABLISHED)
433 goto dropit;
434 if ((tcp_always_keepalive ||
435 inp->inp_socket->so_options & SO_KEEPALIVE) &&
436 tp->t_state <= TCPS_CLOSING) {
437 if (ticks - tp->t_rcvtime >= TP_KEEPIDLE(tp) + TP_MAXIDLE(tp))
438 goto dropit;
439 /*
440 * Send a packet designed to force a response
441 * if the peer is up and reachable:
442 * either an ACK if the connection is still alive,
443 * or an RST if the peer has closed the connection
444 * due to timeout or reboot.
445 * Using sequence number tp->snd_una-1
446 * causes the transmitted zero-length segment
447 * to lie outside the receive window;
448 * by the protocol spec, this requires the
449 * correspondent TCP to respond.
450 */
451 TCPSTAT_INC(tcps_keepprobe);
452 t_template = tcpip_maketemplate(inp);
453 if (t_template) {
454 tcp_respond(tp, t_template->tt_ipgen,
455 &t_template->tt_t, (struct mbuf *)NULL,
456 tp->rcv_nxt, tp->snd_una - 1, 0);
457 free(t_template, M_TEMP);
458 }
459 callout_reset(&tp->t_timers->tt_keep, TP_KEEPINTVL(tp),
460 tcp_timer_keep, tp);
461 } else
462 callout_reset(&tp->t_timers->tt_keep, TP_KEEPIDLE(tp),
463 tcp_timer_keep, tp);
464
465 #ifdef TCPDEBUG
466 if (inp->inp_socket->so_options & SO_DEBUG)
467 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
468 PRU_SLOWTIMO);
469 #endif
470 TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
471 INP_WUNLOCK(inp);
472 CURVNET_RESTORE();
473 return;
474
475 dropit:
476 TCPSTAT_INC(tcps_keepdrops);
477 if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
478 tcp_inpinfo_lock_del(inp, tp);
479 goto out;
480 }
481 INP_INFO_RLOCK_ET(&V_tcbinfo, et);
482 tp = tcp_drop(tp, ETIMEDOUT);
483
484 #ifdef TCPDEBUG
485 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
486 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
487 PRU_SLOWTIMO);
488 #endif
489 TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
490 INP_INFO_RUNLOCK_ET(&V_tcbinfo, et);
491 tcp_inpinfo_lock_del(inp, tp);
492 out:
493 CURVNET_RESTORE();
494 }
495
496 void
tcp_timer_persist(void * xtp)497 tcp_timer_persist(void *xtp)
498 {
499 struct tcpcb *tp = xtp;
500 struct inpcb *inp;
501 struct epoch_tracker et;
502 CURVNET_SET(tp->t_vnet);
503 #ifdef TCPDEBUG
504 int ostate;
505
506 ostate = tp->t_state;
507 #endif
508 inp = tp->t_inpcb;
509 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
510 INP_WLOCK(inp);
511 if (callout_pending(&tp->t_timers->tt_persist) ||
512 !callout_active(&tp->t_timers->tt_persist)) {
513 INP_WUNLOCK(inp);
514 CURVNET_RESTORE();
515 return;
516 }
517 callout_deactivate(&tp->t_timers->tt_persist);
518 if ((inp->inp_flags & INP_DROPPED) != 0) {
519 INP_WUNLOCK(inp);
520 CURVNET_RESTORE();
521 return;
522 }
523 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
524 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
525 /*
526 * Persistence timer into zero window.
527 * Force a byte to be output, if possible.
528 */
529 TCPSTAT_INC(tcps_persisttimeo);
530 /*
531 * Hack: if the peer is dead/unreachable, we do not
532 * time out if the window is closed. After a full
533 * backoff, drop the connection if the idle time
534 * (no responses to probes) reaches the maximum
535 * backoff that we would use if retransmitting.
536 */
537 if (tp->t_rxtshift == TCP_MAXRXTSHIFT &&
538 (ticks - tp->t_rcvtime >= tcp_maxpersistidle ||
539 ticks - tp->t_rcvtime >= TCP_REXMTVAL(tp) * tcp_totbackoff)) {
540 TCPSTAT_INC(tcps_persistdrop);
541 if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
542 tcp_inpinfo_lock_del(inp, tp);
543 goto out;
544 }
545 INP_INFO_RLOCK_ET(&V_tcbinfo, et);
546 tp = tcp_drop(tp, ETIMEDOUT);
547 INP_INFO_RUNLOCK_ET(&V_tcbinfo, et);
548 tcp_inpinfo_lock_del(inp, tp);
549 goto out;
550 }
551 /*
552 * If the user has closed the socket then drop a persisting
553 * connection after a much reduced timeout.
554 */
555 if (tp->t_state > TCPS_CLOSE_WAIT &&
556 (ticks - tp->t_rcvtime) >= TCPTV_PERSMAX) {
557 TCPSTAT_INC(tcps_persistdrop);
558 if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
559 tcp_inpinfo_lock_del(inp, tp);
560 goto out;
561 }
562 INP_INFO_RLOCK_ET(&V_tcbinfo, et);
563 tp = tcp_drop(tp, ETIMEDOUT);
564 INP_INFO_RUNLOCK_ET(&V_tcbinfo, et);
565 tcp_inpinfo_lock_del(inp, tp);
566 goto out;
567 }
568 tcp_setpersist(tp);
569 tp->t_flags |= TF_FORCEDATA;
570 (void) tp->t_fb->tfb_tcp_output(tp);
571 tp->t_flags &= ~TF_FORCEDATA;
572
573 #ifdef TCPDEBUG
574 if (tp != NULL && tp->t_inpcb->inp_socket->so_options & SO_DEBUG)
575 tcp_trace(TA_USER, ostate, tp, NULL, NULL, PRU_SLOWTIMO);
576 #endif
577 TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
578 INP_WUNLOCK(inp);
579 out:
580 CURVNET_RESTORE();
581 }
582
583 void
tcp_timer_rexmt(void * xtp)584 tcp_timer_rexmt(void * xtp)
585 {
586 struct tcpcb *tp = xtp;
587 CURVNET_SET(tp->t_vnet);
588 int rexmt;
589 struct inpcb *inp;
590 struct epoch_tracker et;
591 #ifdef TCPDEBUG
592 int ostate;
593
594 ostate = tp->t_state;
595 #endif
596 inp = tp->t_inpcb;
597 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
598 INP_WLOCK(inp);
599 if (callout_pending(&tp->t_timers->tt_rexmt) ||
600 !callout_active(&tp->t_timers->tt_rexmt)) {
601 INP_WUNLOCK(inp);
602 CURVNET_RESTORE();
603 return;
604 }
605 callout_deactivate(&tp->t_timers->tt_rexmt);
606 if ((inp->inp_flags & INP_DROPPED) != 0) {
607 INP_WUNLOCK(inp);
608 CURVNET_RESTORE();
609 return;
610 }
611 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
612 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
613 tcp_free_sackholes(tp);
614 TCP_LOG_EVENT(tp, NULL, NULL, NULL, TCP_LOG_RTO, 0, 0, NULL, false);
615 if (tp->t_fb->tfb_tcp_rexmit_tmr) {
616 /* The stack has a timer action too. */
617 (*tp->t_fb->tfb_tcp_rexmit_tmr)(tp);
618 }
619 /*
620 * Retransmission timer went off. Message has not
621 * been acked within retransmit interval. Back off
622 * to a longer retransmit interval and retransmit one segment.
623 */
624 if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) {
625 tp->t_rxtshift = TCP_MAXRXTSHIFT;
626 TCPSTAT_INC(tcps_timeoutdrop);
627 if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
628 tcp_inpinfo_lock_del(inp, tp);
629 goto out;
630 }
631 INP_INFO_RLOCK_ET(&V_tcbinfo, et);
632 tp = tcp_drop(tp, ETIMEDOUT);
633 INP_INFO_RUNLOCK_ET(&V_tcbinfo, et);
634 tcp_inpinfo_lock_del(inp, tp);
635 goto out;
636 }
637 if (tp->t_state == TCPS_SYN_SENT) {
638 /*
639 * If the SYN was retransmitted, indicate CWND to be
640 * limited to 1 segment in cc_conn_init().
641 */
642 tp->snd_cwnd = 1;
643 } else if (tp->t_rxtshift == 1) {
644 /*
645 * first retransmit; record ssthresh and cwnd so they can
646 * be recovered if this turns out to be a "bad" retransmit.
647 * A retransmit is considered "bad" if an ACK for this
648 * segment is received within RTT/2 interval; the assumption
649 * here is that the ACK was already in flight. See
650 * "On Estimating End-to-End Network Path Properties" by
651 * Allman and Paxson for more details.
652 */
653 tp->snd_cwnd_prev = tp->snd_cwnd;
654 tp->snd_ssthresh_prev = tp->snd_ssthresh;
655 tp->snd_recover_prev = tp->snd_recover;
656 if (IN_FASTRECOVERY(tp->t_flags))
657 tp->t_flags |= TF_WASFRECOVERY;
658 else
659 tp->t_flags &= ~TF_WASFRECOVERY;
660 if (IN_CONGRECOVERY(tp->t_flags))
661 tp->t_flags |= TF_WASCRECOVERY;
662 else
663 tp->t_flags &= ~TF_WASCRECOVERY;
664 if ((tp->t_flags & TF_RCVD_TSTMP) == 0)
665 tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1));
666 /* In the event that we've negotiated timestamps
667 * badrxtwin will be set to the value that we set
668 * the retransmitted packet's to_tsval to by tcp_output
669 */
670 tp->t_flags |= TF_PREVVALID;
671 } else
672 tp->t_flags &= ~TF_PREVVALID;
673 TCPSTAT_INC(tcps_rexmttimeo);
674 if ((tp->t_state == TCPS_SYN_SENT) ||
675 (tp->t_state == TCPS_SYN_RECEIVED))
676 rexmt = tcp_rexmit_initial * tcp_backoff[tp->t_rxtshift];
677 else
678 rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift];
679 TCPT_RANGESET(tp->t_rxtcur, rexmt,
680 tp->t_rttmin, TCPTV_REXMTMAX);
681
682 /*
683 * We enter the path for PLMTUD if connection is established or, if
684 * connection is FIN_WAIT_1 status, reason for the last is that if
685 * amount of data we send is very small, we could send it in couple of
686 * packets and process straight to FIN. In that case we won't catch
687 * ESTABLISHED state.
688 */
689 if (V_tcp_pmtud_blackhole_detect && (((tp->t_state == TCPS_ESTABLISHED))
690 || (tp->t_state == TCPS_FIN_WAIT_1))) {
691 #ifdef INET6
692 int isipv6;
693 #endif
694
695 /*
696 * Idea here is that at each stage of mtu probe (usually, 1448
697 * -> 1188 -> 524) should be given 2 chances to recover before
698 * further clamping down. 'tp->t_rxtshift % 2 == 0' should
699 * take care of that.
700 */
701 if (((tp->t_flags2 & (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) ==
702 (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) &&
703 (tp->t_rxtshift >= 2 && tp->t_rxtshift < 6 &&
704 tp->t_rxtshift % 2 == 0)) {
705 /*
706 * Enter Path MTU Black-hole Detection mechanism:
707 * - Disable Path MTU Discovery (IP "DF" bit).
708 * - Reduce MTU to lower value than what we
709 * negotiated with peer.
710 */
711 if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) == 0) {
712 /* Record that we may have found a black hole. */
713 tp->t_flags2 |= TF2_PLPMTU_BLACKHOLE;
714 /* Keep track of previous MSS. */
715 tp->t_pmtud_saved_maxseg = tp->t_maxseg;
716 }
717
718 /*
719 * Reduce the MSS to blackhole value or to the default
720 * in an attempt to retransmit.
721 */
722 #ifdef INET6
723 isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) ? 1 : 0;
724 if (isipv6 &&
725 tp->t_maxseg > V_tcp_v6pmtud_blackhole_mss) {
726 /* Use the sysctl tuneable blackhole MSS. */
727 tp->t_maxseg = V_tcp_v6pmtud_blackhole_mss;
728 TCPSTAT_INC(tcps_pmtud_blackhole_activated);
729 } else if (isipv6) {
730 /* Use the default MSS. */
731 tp->t_maxseg = V_tcp_v6mssdflt;
732 /*
733 * Disable Path MTU Discovery when we switch to
734 * minmss.
735 */
736 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
737 TCPSTAT_INC(tcps_pmtud_blackhole_activated_min_mss);
738 }
739 #endif
740 #if defined(INET6) && defined(INET)
741 else
742 #endif
743 #ifdef INET
744 if (tp->t_maxseg > V_tcp_pmtud_blackhole_mss) {
745 /* Use the sysctl tuneable blackhole MSS. */
746 tp->t_maxseg = V_tcp_pmtud_blackhole_mss;
747 TCPSTAT_INC(tcps_pmtud_blackhole_activated);
748 } else {
749 /* Use the default MSS. */
750 tp->t_maxseg = V_tcp_mssdflt;
751 /*
752 * Disable Path MTU Discovery when we switch to
753 * minmss.
754 */
755 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
756 TCPSTAT_INC(tcps_pmtud_blackhole_activated_min_mss);
757 }
758 #endif
759 /*
760 * Reset the slow-start flight size
761 * as it may depend on the new MSS.
762 */
763 if (CC_ALGO(tp)->conn_init != NULL)
764 CC_ALGO(tp)->conn_init(tp->ccv);
765 } else {
766 /*
767 * If further retransmissions are still unsuccessful
768 * with a lowered MTU, maybe this isn't a blackhole and
769 * we restore the previous MSS and blackhole detection
770 * flags.
771 * The limit '6' is determined by giving each probe
772 * stage (1448, 1188, 524) 2 chances to recover.
773 */
774 if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) &&
775 (tp->t_rxtshift >= 6)) {
776 tp->t_flags2 |= TF2_PLPMTU_PMTUD;
777 tp->t_flags2 &= ~TF2_PLPMTU_BLACKHOLE;
778 tp->t_maxseg = tp->t_pmtud_saved_maxseg;
779 TCPSTAT_INC(tcps_pmtud_blackhole_failed);
780 /*
781 * Reset the slow-start flight size as it
782 * may depend on the new MSS.
783 */
784 if (CC_ALGO(tp)->conn_init != NULL)
785 CC_ALGO(tp)->conn_init(tp->ccv);
786 }
787 }
788 }
789
790 /*
791 * Disable RFC1323 and SACK if we haven't got any response to
792 * our third SYN to work-around some broken terminal servers
793 * (most of which have hopefully been retired) that have bad VJ
794 * header compression code which trashes TCP segments containing
795 * unknown-to-them TCP options.
796 */
797 if (tcp_rexmit_drop_options && (tp->t_state == TCPS_SYN_SENT) &&
798 (tp->t_rxtshift == 3))
799 tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP|TF_SACK_PERMIT);
800 /*
801 * If we backed off this far, notify the L3 protocol that we're having
802 * connection problems.
803 */
804 if (tp->t_rxtshift > TCP_RTT_INVALIDATE) {
805 #ifdef INET6
806 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0)
807 in6_losing(tp->t_inpcb);
808 else
809 #endif
810 in_losing(tp->t_inpcb);
811 }
812 tp->snd_nxt = tp->snd_una;
813 tp->snd_recover = tp->snd_max;
814 /*
815 * Force a segment to be sent.
816 */
817 tp->t_flags |= TF_ACKNOW;
818 /*
819 * If timing a segment in this window, stop the timer.
820 */
821 tp->t_rtttime = 0;
822
823 cc_cong_signal(tp, NULL, CC_RTO);
824
825 (void) tp->t_fb->tfb_tcp_output(tp);
826
827 #ifdef TCPDEBUG
828 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
829 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
830 PRU_SLOWTIMO);
831 #endif
832 TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
833 INP_WUNLOCK(inp);
834 out:
835 CURVNET_RESTORE();
836 }
837
838 void
tcp_timer_activate(struct tcpcb * tp,uint32_t timer_type,u_int delta)839 tcp_timer_activate(struct tcpcb *tp, uint32_t timer_type, u_int delta)
840 {
841 struct callout *t_callout;
842 timeout_t *f_callout;
843 struct inpcb *inp = tp->t_inpcb;
844 int cpu = inp_to_cpuid(inp);
845
846 #ifdef TCP_OFFLOAD
847 if (tp->t_flags & TF_TOE)
848 return;
849 #endif
850
851 if (tp->t_timers->tt_flags & TT_STOPPED)
852 return;
853
854 switch (timer_type) {
855 case TT_DELACK:
856 t_callout = &tp->t_timers->tt_delack;
857 f_callout = tcp_timer_delack;
858 break;
859 case TT_REXMT:
860 t_callout = &tp->t_timers->tt_rexmt;
861 f_callout = tcp_timer_rexmt;
862 break;
863 case TT_PERSIST:
864 t_callout = &tp->t_timers->tt_persist;
865 f_callout = tcp_timer_persist;
866 break;
867 case TT_KEEP:
868 t_callout = &tp->t_timers->tt_keep;
869 f_callout = tcp_timer_keep;
870 break;
871 case TT_2MSL:
872 t_callout = &tp->t_timers->tt_2msl;
873 f_callout = tcp_timer_2msl;
874 break;
875 default:
876 if (tp->t_fb->tfb_tcp_timer_activate) {
877 tp->t_fb->tfb_tcp_timer_activate(tp, timer_type, delta);
878 return;
879 }
880 panic("tp %p bad timer_type %#x", tp, timer_type);
881 }
882 if (delta == 0) {
883 callout_stop(t_callout);
884 } else {
885 callout_reset_on(t_callout, delta, f_callout, tp, cpu);
886 }
887 }
888
889 int
tcp_timer_active(struct tcpcb * tp,uint32_t timer_type)890 tcp_timer_active(struct tcpcb *tp, uint32_t timer_type)
891 {
892 struct callout *t_callout;
893
894 switch (timer_type) {
895 case TT_DELACK:
896 t_callout = &tp->t_timers->tt_delack;
897 break;
898 case TT_REXMT:
899 t_callout = &tp->t_timers->tt_rexmt;
900 break;
901 case TT_PERSIST:
902 t_callout = &tp->t_timers->tt_persist;
903 break;
904 case TT_KEEP:
905 t_callout = &tp->t_timers->tt_keep;
906 break;
907 case TT_2MSL:
908 t_callout = &tp->t_timers->tt_2msl;
909 break;
910 default:
911 if (tp->t_fb->tfb_tcp_timer_active) {
912 return(tp->t_fb->tfb_tcp_timer_active(tp, timer_type));
913 }
914 panic("tp %p bad timer_type %#x", tp, timer_type);
915 }
916 return callout_active(t_callout);
917 }
918
919 /*
920 * Stop the timer from running, and apply a flag
921 * against the timer_flags that will force the
922 * timer never to run. The flag is needed to assure
923 * a race does not leave it running and cause
924 * the timer to possibly restart itself (keep and persist
925 * especially do this).
926 */
927 int
tcp_timer_suspend(struct tcpcb * tp,uint32_t timer_type)928 tcp_timer_suspend(struct tcpcb *tp, uint32_t timer_type)
929 {
930 struct callout *t_callout;
931 uint32_t t_flags;
932
933 switch (timer_type) {
934 case TT_DELACK:
935 t_flags = TT_DELACK_SUS;
936 t_callout = &tp->t_timers->tt_delack;
937 break;
938 case TT_REXMT:
939 t_flags = TT_REXMT_SUS;
940 t_callout = &tp->t_timers->tt_rexmt;
941 break;
942 case TT_PERSIST:
943 t_flags = TT_PERSIST_SUS;
944 t_callout = &tp->t_timers->tt_persist;
945 break;
946 case TT_KEEP:
947 t_flags = TT_KEEP_SUS;
948 t_callout = &tp->t_timers->tt_keep;
949 break;
950 case TT_2MSL:
951 t_flags = TT_2MSL_SUS;
952 t_callout = &tp->t_timers->tt_2msl;
953 break;
954 default:
955 panic("tp:%p bad timer_type 0x%x", tp, timer_type);
956 }
957 tp->t_timers->tt_flags |= t_flags;
958 return (callout_stop(t_callout));
959 }
960
961 void
tcp_timers_unsuspend(struct tcpcb * tp,uint32_t timer_type)962 tcp_timers_unsuspend(struct tcpcb *tp, uint32_t timer_type)
963 {
964 switch (timer_type) {
965 case TT_DELACK:
966 if (tp->t_timers->tt_flags & TT_DELACK_SUS) {
967 tp->t_timers->tt_flags &= ~TT_DELACK_SUS;
968 if (tp->t_flags & TF_DELACK) {
969 /* Delayed ack timer should be up activate a timer */
970 tp->t_flags &= ~TF_DELACK;
971 tcp_timer_activate(tp, TT_DELACK,
972 tcp_delacktime);
973 }
974 }
975 break;
976 case TT_REXMT:
977 if (tp->t_timers->tt_flags & TT_REXMT_SUS) {
978 tp->t_timers->tt_flags &= ~TT_REXMT_SUS;
979 if (SEQ_GT(tp->snd_max, tp->snd_una) &&
980 (tcp_timer_active((tp), TT_PERSIST) == 0) &&
981 tp->snd_wnd) {
982 /* We have outstanding data activate a timer */
983 tcp_timer_activate(tp, TT_REXMT,
984 tp->t_rxtcur);
985 }
986 }
987 break;
988 case TT_PERSIST:
989 if (tp->t_timers->tt_flags & TT_PERSIST_SUS) {
990 tp->t_timers->tt_flags &= ~TT_PERSIST_SUS;
991 if (tp->snd_wnd == 0) {
992 /* Activate the persists timer */
993 tp->t_rxtshift = 0;
994 tcp_setpersist(tp);
995 }
996 }
997 break;
998 case TT_KEEP:
999 if (tp->t_timers->tt_flags & TT_KEEP_SUS) {
1000 tp->t_timers->tt_flags &= ~TT_KEEP_SUS;
1001 tcp_timer_activate(tp, TT_KEEP,
1002 TCPS_HAVEESTABLISHED(tp->t_state) ?
1003 TP_KEEPIDLE(tp) : TP_KEEPINIT(tp));
1004 }
1005 break;
1006 case TT_2MSL:
1007 if (tp->t_timers->tt_flags &= TT_2MSL_SUS) {
1008 tp->t_timers->tt_flags &= ~TT_2MSL_SUS;
1009 if ((tp->t_state == TCPS_FIN_WAIT_2) &&
1010 ((tp->t_inpcb->inp_socket == NULL) ||
1011 (tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE))) {
1012 /* Star the 2MSL timer */
1013 tcp_timer_activate(tp, TT_2MSL,
1014 (tcp_fast_finwait2_recycle) ?
1015 tcp_finwait2_timeout : TP_MAXIDLE(tp));
1016 }
1017 }
1018 break;
1019 default:
1020 panic("tp:%p bad timer_type 0x%x", tp, timer_type);
1021 }
1022 }
1023
1024 void
tcp_timer_stop(struct tcpcb * tp,uint32_t timer_type)1025 tcp_timer_stop(struct tcpcb *tp, uint32_t timer_type)
1026 {
1027 struct callout *t_callout;
1028
1029 tp->t_timers->tt_flags |= TT_STOPPED;
1030 switch (timer_type) {
1031 case TT_DELACK:
1032 t_callout = &tp->t_timers->tt_delack;
1033 break;
1034 case TT_REXMT:
1035 t_callout = &tp->t_timers->tt_rexmt;
1036 break;
1037 case TT_PERSIST:
1038 t_callout = &tp->t_timers->tt_persist;
1039 break;
1040 case TT_KEEP:
1041 t_callout = &tp->t_timers->tt_keep;
1042 break;
1043 case TT_2MSL:
1044 t_callout = &tp->t_timers->tt_2msl;
1045 break;
1046 default:
1047 if (tp->t_fb->tfb_tcp_timer_stop) {
1048 /*
1049 * XXXrrs we need to look at this with the
1050 * stop case below (flags).
1051 */
1052 tp->t_fb->tfb_tcp_timer_stop(tp, timer_type);
1053 return;
1054 }
1055 panic("tp %p bad timer_type %#x", tp, timer_type);
1056 }
1057
1058 if (callout_async_drain(t_callout, tcp_timer_discard) == 0) {
1059 /*
1060 * Can't stop the callout, defer tcpcb actual deletion
1061 * to the last one. We do this using the async drain
1062 * function and incrementing the count in
1063 */
1064 tp->t_timers->tt_draincnt++;
1065 }
1066 }
1067