sys/netinet/tcp_timer.c

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