1139823Simp/*- 211150Swollman * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995 31541Srgrimes * The Regents of the University of California. All rights reserved. 41541Srgrimes * 51541Srgrimes * Redistribution and use in source and binary forms, with or without 61541Srgrimes * modification, are permitted provided that the following conditions 71541Srgrimes * are met: 81541Srgrimes * 1. Redistributions of source code must retain the above copyright 91541Srgrimes * notice, this list of conditions and the following disclaimer. 101541Srgrimes * 2. Redistributions in binary form must reproduce the above copyright 111541Srgrimes * notice, this list of conditions and the following disclaimer in the 121541Srgrimes * documentation and/or other materials provided with the distribution. 131541Srgrimes * 4. Neither the name of the University nor the names of its contributors 141541Srgrimes * may be used to endorse or promote products derived from this software 151541Srgrimes * without specific prior written permission. 161541Srgrimes * 171541Srgrimes * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 181541Srgrimes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 191541Srgrimes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 201541Srgrimes * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 211541Srgrimes * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 221541Srgrimes * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 231541Srgrimes * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 241541Srgrimes * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 251541Srgrimes * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 261541Srgrimes * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 271541Srgrimes * SUCH DAMAGE. 281541Srgrimes * 2911150Swollman * @(#)tcp_subr.c 8.2 (Berkeley) 5/24/95 301541Srgrimes */ 311541Srgrimes 32172467Ssilby#include <sys/cdefs.h> 33172467Ssilby__FBSDID("$FreeBSD: stable/10/sys/netinet/tcp_timewait.c 309108 2016-11-24 14:48:46Z jch $"); 34172467Ssilby 35125680Sbms#include "opt_inet.h" 3654263Sshin#include "opt_inet6.h" 3729514Sjoerg#include "opt_tcpdebug.h" 3829514Sjoerg 391541Srgrimes#include <sys/param.h> 401541Srgrimes#include <sys/systm.h> 4150673Sjlemon#include <sys/callout.h> 4212172Sphk#include <sys/kernel.h> 4312172Sphk#include <sys/sysctl.h> 441541Srgrimes#include <sys/malloc.h> 451541Srgrimes#include <sys/mbuf.h> 46164033Srwatson#include <sys/priv.h> 4748758Sgreen#include <sys/proc.h> 481541Srgrimes#include <sys/socket.h> 491541Srgrimes#include <sys/socketvar.h> 501541Srgrimes#include <sys/protosw.h> 5175619Skris#include <sys/random.h> 5234923Sbde 5392760Sjeff#include <vm/uma.h> 541541Srgrimes 551541Srgrimes#include <net/route.h> 561541Srgrimes#include <net/if.h> 57196019Srwatson#include <net/vnet.h> 581541Srgrimes 591541Srgrimes#include <netinet/in.h> 60221250Sbz#include <netinet/in_pcb.h> 611541Srgrimes#include <netinet/in_systm.h> 62221250Sbz#include <netinet/in_var.h> 631541Srgrimes#include <netinet/ip.h> 64221250Sbz#include <netinet/ip_icmp.h> 65221250Sbz#include <netinet/ip_var.h> 6655679Sshin#ifdef INET6 6755679Sshin#include <netinet/ip6.h> 6855679Sshin#include <netinet6/in6_pcb.h> 6955679Sshin#include <netinet6/ip6_var.h> 70148385Sume#include <netinet6/scope6_var.h> 71122922Sandre#include <netinet6/nd6.h> 7255679Sshin#endif 731541Srgrimes#include <netinet/tcp.h> 741541Srgrimes#include <netinet/tcp_fsm.h> 751541Srgrimes#include <netinet/tcp_seq.h> 761541Srgrimes#include <netinet/tcp_timer.h> 771541Srgrimes#include <netinet/tcp_var.h> 7855679Sshin#ifdef INET6 7955679Sshin#include <netinet6/tcp6_var.h> 8055679Sshin#endif 811541Srgrimes#include <netinet/tcpip.h> 826283Swollman#ifdef TCPDEBUG 836283Swollman#include <netinet/tcp_debug.h> 846283Swollman#endif 85221250Sbz#ifdef INET6 8655679Sshin#include <netinet6/ip6protosw.h> 87221250Sbz#endif 881541Srgrimes 8958698Sjlemon#include <machine/in_cksum.h> 9058698Sjlemon 91163606Srwatson#include <security/mac/mac_framework.h> 92163606Srwatson 93215701Sdimstatic VNET_DEFINE(uma_zone_t, tcptw_zone); 94275402Sjch#define V_tcptw_zone VNET(tcptw_zone) 95157478Sglebiusstatic int maxtcptw; 96162767Ssilby 97169608Sandre/* 98169608Sandre * The timed wait queue contains references to each of the TCP sessions 99169608Sandre * currently in the TIME_WAIT state. The queue pointers, including the 100169608Sandre * queue pointers in each tcptw structure, are protected using the global 101275402Sjch * timewait lock, which must be held over queue iteration and modification. 102275402Sjch * 103275402Sjch * Rules on tcptw usage: 104275402Sjch * - a inpcb is always freed _after_ its tcptw 105275402Sjch * - a tcptw relies on its inpcb reference counting for memory stability 106275402Sjch * - a tcptw is dereferenceable only while its inpcb is locked 107169608Sandre */ 108215701Sdimstatic VNET_DEFINE(TAILQ_HEAD(, tcptw), twq_2msl); 109275402Sjch#define V_twq_2msl VNET(twq_2msl) 110195699Srwatson 111275402Sjch/* Global timewait lock */ 112275402Sjchstatic VNET_DEFINE(struct rwlock, tw_lock); 113275402Sjch#define V_tw_lock VNET(tw_lock) 114275402Sjch 115275402Sjch#define TW_LOCK_INIT(tw, d) rw_init_flags(&(tw), (d), 0) 116275402Sjch#define TW_LOCK_DESTROY(tw) rw_destroy(&(tw)) 117275402Sjch#define TW_RLOCK(tw) rw_rlock(&(tw)) 118275402Sjch#define TW_WLOCK(tw) rw_wlock(&(tw)) 119275402Sjch#define TW_RUNLOCK(tw) rw_runlock(&(tw)) 120275402Sjch#define TW_WUNLOCK(tw) rw_wunlock(&(tw)) 121275402Sjch#define TW_LOCK_ASSERT(tw) rw_assert(&(tw), RA_LOCKED) 122275402Sjch#define TW_RLOCK_ASSERT(tw) rw_assert(&(tw), RA_RLOCKED) 123275402Sjch#define TW_WLOCK_ASSERT(tw) rw_assert(&(tw), RA_WLOCKED) 124275402Sjch#define TW_UNLOCK_ASSERT(tw) rw_assert(&(tw), RA_UNLOCKED) 125275402Sjch 126169608Sandrestatic void tcp_tw_2msl_reset(struct tcptw *, int); 127275402Sjchstatic void tcp_tw_2msl_stop(struct tcptw *, int); 128270054Sbzstatic int tcp_twrespond(struct tcptw *, int); 129169608Sandre 130162031Sglebiusstatic int 131162767Ssilbytcptw_auto_size(void) 132162767Ssilby{ 133162767Ssilby int halfrange; 134162767Ssilby 135162767Ssilby /* 136162768Smaxim * Max out at half the ephemeral port range so that TIME_WAIT 137162768Smaxim * sockets don't tie up too many ephemeral ports. 138162768Smaxim */ 139181803Sbz if (V_ipport_lastauto > V_ipport_firstauto) 140181803Sbz halfrange = (V_ipport_lastauto - V_ipport_firstauto) / 2; 141162767Ssilby else 142181803Sbz halfrange = (V_ipport_firstauto - V_ipport_lastauto) / 2; 143162767Ssilby /* Protect against goofy port ranges smaller than 32. */ 144162767Ssilby return (imin(imax(halfrange, 32), maxsockets / 5)); 145162767Ssilby} 146162767Ssilby 147162767Ssilbystatic int 148162031Sglebiussysctl_maxtcptw(SYSCTL_HANDLER_ARGS) 149162031Sglebius{ 150162031Sglebius int error, new; 151157478Sglebius 152162031Sglebius if (maxtcptw == 0) 153162767Ssilby new = tcptw_auto_size(); 154162031Sglebius else 155162031Sglebius new = maxtcptw; 156170289Sdwmalone error = sysctl_handle_int(oidp, &new, 0, req); 157162767Ssilby if (error == 0 && req->newptr) 158162767Ssilby if (new >= 32) { 159162031Sglebius maxtcptw = new; 160190787Szec uma_zone_set_max(V_tcptw_zone, maxtcptw); 161162767Ssilby } 162162031Sglebius return (error); 163162031Sglebius} 164169541Sandre 165162031SglebiusSYSCTL_PROC(_net_inet_tcp, OID_AUTO, maxtcptw, CTLTYPE_INT|CTLFLAG_RW, 166162031Sglebius &maxtcptw, 0, sysctl_maxtcptw, "IU", 167162031Sglebius "Maximum number of compressed TCP TIME_WAIT entries"); 168162031Sglebius 169207369SbzVNET_DEFINE(int, nolocaltimewait) = 0; 170207369Sbz#define V_nolocaltimewait VNET(nolocaltimewait) 171195699SrwatsonSYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, nolocaltimewait, CTLFLAG_RW, 172195699Srwatson &VNET_NAME(nolocaltimewait), 0, 173167721Sandre "Do not create compressed TCP TIME_WAIT entries for local connections"); 174162151Sglebius 175169541Sandrevoid 176169541Sandretcp_tw_zone_change(void) 177157927Sps{ 178157927Sps 179162031Sglebius if (maxtcptw == 0) 180190787Szec uma_zone_set_max(V_tcptw_zone, tcptw_auto_size()); 181157927Sps} 182157927Sps 1831541Srgrimesvoid 184169541Sandretcp_tw_init(void) 1851541Srgrimes{ 186169454Srwatson 187190787Szec V_tcptw_zone = uma_zcreate("tcptw", sizeof(struct tcptw), 188162031Sglebius NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 189157478Sglebius TUNABLE_INT_FETCH("net.inet.tcp.maxtcptw", &maxtcptw); 190157478Sglebius if (maxtcptw == 0) 191190787Szec uma_zone_set_max(V_tcptw_zone, tcptw_auto_size()); 192162031Sglebius else 193190787Szec uma_zone_set_max(V_tcptw_zone, maxtcptw); 194181803Sbz TAILQ_INIT(&V_twq_2msl); 195275402Sjch TW_LOCK_INIT(V_tw_lock, "tcptw"); 1961541Srgrimes} 1971541Srgrimes 198193731Szec#ifdef VIMAGE 199193731Szecvoid 200193731Szectcp_tw_destroy(void) 201193731Szec{ 202193731Szec struct tcptw *tw; 203193731Szec 204309108Sjch INP_INFO_RLOCK(&V_tcbinfo); 205275402Sjch while ((tw = TAILQ_FIRST(&V_twq_2msl)) != NULL) 206193731Szec tcp_twclose(tw, 0); 207309108Sjch INP_INFO_RUNLOCK(&V_tcbinfo); 208204838Sbz 209275402Sjch TW_LOCK_DESTROY(V_tw_lock); 210204838Sbz uma_zdestroy(V_tcptw_zone); 211193731Szec} 212193731Szec#endif 213193731Szec 2141541Srgrimes/* 215111145Sjlemon * Move a TCP connection into TIME_WAIT state. 216138410Srwatson * tcbinfo is locked. 217111145Sjlemon * inp is locked, and is unlocked before returning. 218111145Sjlemon */ 219111145Sjlemonvoid 220157431Srwatsontcp_twstart(struct tcpcb *tp) 221111145Sjlemon{ 222111145Sjlemon struct tcptw *tw; 223162151Sglebius struct inpcb *inp = tp->t_inpcb; 224162111Sru int acknow; 225111145Sjlemon struct socket *so; 226221250Sbz#ifdef INET6 227221250Sbz int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6; 228221250Sbz#endif 229111145Sjlemon 230309108Sjch INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 231178285Srwatson INP_WLOCK_ASSERT(inp); 232138020Srwatson 233307906Sjch /* A dropped inp should never transition to TIME_WAIT state. */ 234307906Sjch KASSERT((inp->inp_flags & INP_DROPPED) == 0, ("tcp_twstart: " 235307906Sjch "(inp->inp_flags & INP_DROPPED) != 0")); 236307906Sjch 237221250Sbz if (V_nolocaltimewait) { 238221250Sbz int error = 0; 239221250Sbz#ifdef INET6 240221250Sbz if (isipv6) 241221250Sbz error = in6_localaddr(&inp->in6p_faddr); 242221250Sbz#endif 243221250Sbz#if defined(INET6) && defined(INET) 244221250Sbz else 245221250Sbz#endif 246221250Sbz#ifdef INET 247221250Sbz error = in_localip(inp->inp_faddr); 248221250Sbz#endif 249221250Sbz if (error) { 250221250Sbz tp = tcp_close(tp); 251221250Sbz if (tp != NULL) 252221250Sbz INP_WUNLOCK(inp); 253221250Sbz return; 254221250Sbz } 255162151Sglebius } 256162151Sglebius 257282826Sgnn 258282826Sgnn /* 259282826Sgnn * For use only by DTrace. We do not reference the state 260282826Sgnn * after this point so modifying it in place is not a problem. 261282826Sgnn */ 262282826Sgnn tcp_state_change(tp, TCPS_TIME_WAIT); 263282826Sgnn 264190787Szec tw = uma_zalloc(V_tcptw_zone, M_NOWAIT); 265112009Sjlemon if (tw == NULL) { 266275402Sjch /* 267275402Sjch * Reached limit on total number of TIMEWAIT connections 268275402Sjch * allowed. Remove a connection from TIMEWAIT queue in LRU 269275402Sjch * fashion to make room for this connection. 270275402Sjch * 271309108Sjch * XXX: Check if it possible to always have enough room 272309108Sjch * in advance based on guarantees provided by uma_zalloc(). 273275402Sjch */ 274169608Sandre tw = tcp_tw_2msl_scan(1); 275112009Sjlemon if (tw == NULL) { 276157376Srwatson tp = tcp_close(tp); 277157376Srwatson if (tp != NULL) 278178285Srwatson INP_WUNLOCK(inp); 279112009Sjlemon return; 280112009Sjlemon } 281112009Sjlemon } 282275402Sjch /* 283275402Sjch * The tcptw will hold a reference on its inpcb until tcp_twclose 284275402Sjch * is called 285275402Sjch */ 286111145Sjlemon tw->tw_inpcb = inp; 287275402Sjch in_pcbref(inp); /* Reference from tw */ 288111145Sjlemon 289111145Sjlemon /* 290111145Sjlemon * Recover last window size sent. 291111145Sjlemon */ 292229700Sjhb if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt)) 293229665Sjhb tw->last_win = (tp->rcv_adv - tp->rcv_nxt) >> tp->rcv_scale; 294229665Sjhb else 295229665Sjhb tw->last_win = 0; 296111145Sjlemon 297111145Sjlemon /* 298111145Sjlemon * Set t_recent if timestamps are used on the connection. 299111145Sjlemon */ 300133874Srwatson if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) == 301169477Sandre (TF_REQ_TSTMP|TF_RCVD_TSTMP)) { 302111145Sjlemon tw->t_recent = tp->ts_recent; 303169477Sandre tw->ts_offset = tp->ts_offset; 304169477Sandre } else { 305111145Sjlemon tw->t_recent = 0; 306169477Sandre tw->ts_offset = 0; 307169477Sandre } 308111145Sjlemon 309111145Sjlemon tw->snd_nxt = tp->snd_nxt; 310111145Sjlemon tw->rcv_nxt = tp->rcv_nxt; 311121850Ssilby tw->iss = tp->iss; 312121884Ssilby tw->irs = tp->irs; 313111145Sjlemon tw->t_starttime = tp->t_starttime; 314112009Sjlemon tw->tw_time = 0; 315111145Sjlemon 316111145Sjlemon/* XXX 317111145Sjlemon * If this code will 318111145Sjlemon * be used for fin-wait-2 state also, then we may need 319111145Sjlemon * a ts_recent from the last segment. 320111145Sjlemon */ 321137139Sandre acknow = tp->t_flags & TF_ACKNOW; 322157376Srwatson 323157376Srwatson /* 324157376Srwatson * First, discard tcpcb state, which includes stopping its timers and 325157376Srwatson * freeing it. tcp_discardcb() used to also release the inpcb, but 326157376Srwatson * that work is now done in the caller. 327160925Srwatson * 328160925Srwatson * Note: soisdisconnected() call used to be made in tcp_discardcb(), 329160925Srwatson * and might not be needed here any longer. 330157376Srwatson */ 331111145Sjlemon tcp_discardcb(tp); 332111145Sjlemon so = inp->inp_socket; 333160925Srwatson soisdisconnected(so); 334169347Srwatson tw->tw_cred = crhold(so->so_cred); 335130387Srwatson SOCK_LOCK(so); 336111145Sjlemon tw->tw_so_options = so->so_options; 337157376Srwatson SOCK_UNLOCK(so); 338114794Srwatson if (acknow) 339126351Srwatson tcp_twrespond(tw, TH_ACK); 340157432Srwatson inp->inp_ppcb = tw; 341189848Srwatson inp->inp_flags |= INP_TIMEWAIT; 342169608Sandre tcp_tw_2msl_reset(tw, 0); 343157376Srwatson 344157376Srwatson /* 345157376Srwatson * If the inpcb owns the sole reference to the socket, then we can 346157376Srwatson * detach and free the socket as it is not needed in time wait. 347157376Srwatson */ 348189848Srwatson if (inp->inp_flags & INP_SOCKREF) { 349157376Srwatson KASSERT(so->so_state & SS_PROTOREF, 350157376Srwatson ("tcp_twstart: !SS_PROTOREF")); 351189848Srwatson inp->inp_flags &= ~INP_SOCKREF; 352178285Srwatson INP_WUNLOCK(inp); 353157376Srwatson ACCEPT_LOCK(); 354157376Srwatson SOCK_LOCK(so); 355157376Srwatson so->so_state &= ~SS_PROTOREF; 356157376Srwatson sofree(so); 357157376Srwatson } else 358178285Srwatson INP_WUNLOCK(inp); 359111145Sjlemon} 360111145Sjlemon 361162064Sglebius#if 0 362121850Ssilby/* 363121884Ssilby * The appromixate rate of ISN increase of Microsoft TCP stacks; 364121884Ssilby * the actual rate is slightly higher due to the addition of 365121884Ssilby * random positive increments. 366121884Ssilby * 367121884Ssilby * Most other new OSes use semi-randomized ISN values, so we 368121884Ssilby * do not need to worry about them. 369121884Ssilby */ 370275402Sjch#define MS_ISN_BYTES_PER_SECOND 250000 371121884Ssilby 372121884Ssilby/* 373121850Ssilby * Determine if the ISN we will generate has advanced beyond the last 374121850Ssilby * sequence number used by the previous connection. If so, indicate 375121850Ssilby * that it is safe to recycle this tw socket by returning 1. 376121850Ssilby */ 377121850Ssilbyint 378121850Ssilbytcp_twrecycleable(struct tcptw *tw) 379121850Ssilby{ 380121884Ssilby tcp_seq new_iss = tw->iss; 381121884Ssilby tcp_seq new_irs = tw->irs; 382121850Ssilby 383309108Sjch INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 384121884Ssilby new_iss += (ticks - tw->t_starttime) * (ISN_BYTES_PER_SECOND / hz); 385121884Ssilby new_irs += (ticks - tw->t_starttime) * (MS_ISN_BYTES_PER_SECOND / hz); 386133874Srwatson 387121884Ssilby if (SEQ_GT(new_iss, tw->snd_nxt) && SEQ_GT(new_irs, tw->rcv_nxt)) 388139222Srwatson return (1); 389121850Ssilby else 390139222Srwatson return (0); 391121850Ssilby} 392162064Sglebius#endif 393121850Ssilby 394169608Sandre/* 395169608Sandre * Returns 1 if the TIME_WAIT state was killed and we should start over, 396169608Sandre * looking for a pcb in the listen state. Returns 0 otherwise. 397169608Sandre */ 398169608Sandreint 399270057Sbztcp_twcheck(struct inpcb *inp, struct tcpopt *to __unused, struct tcphdr *th, 400169608Sandre struct mbuf *m, int tlen) 401169608Sandre{ 402169608Sandre struct tcptw *tw; 403169608Sandre int thflags; 404169608Sandre tcp_seq seq; 405169608Sandre 406309108Sjch INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 407178285Srwatson INP_WLOCK_ASSERT(inp); 408169608Sandre 409169608Sandre /* 410169608Sandre * XXXRW: Time wait state for inpcb has been recycled, but inpcb is 411169608Sandre * still present. This is undesirable, but temporarily necessary 412169608Sandre * until we work out how to handle inpcb's who's timewait state has 413169608Sandre * been removed. 414169608Sandre */ 415169608Sandre tw = intotw(inp); 416169608Sandre if (tw == NULL) 417169608Sandre goto drop; 418169608Sandre 419169608Sandre thflags = th->th_flags; 420169608Sandre 421169608Sandre /* 422169608Sandre * NOTE: for FIN_WAIT_2 (to be added later), 423169608Sandre * must validate sequence number before accepting RST 424169608Sandre */ 425169608Sandre 426169608Sandre /* 427169608Sandre * If the segment contains RST: 428169608Sandre * Drop the segment - see Stevens, vol. 2, p. 964 and 429169608Sandre * RFC 1337. 430169608Sandre */ 431169608Sandre if (thflags & TH_RST) 432169608Sandre goto drop; 433169608Sandre 434169608Sandre#if 0 435169608Sandre/* PAWS not needed at the moment */ 436169608Sandre /* 437169608Sandre * RFC 1323 PAWS: If we have a timestamp reply on this segment 438169608Sandre * and it's less than ts_recent, drop it. 439169608Sandre */ 440169608Sandre if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent && 441169608Sandre TSTMP_LT(to.to_tsval, tp->ts_recent)) { 442169608Sandre if ((thflags & TH_ACK) == 0) 443169608Sandre goto drop; 444169608Sandre goto ack; 445169608Sandre } 446169608Sandre /* 447169608Sandre * ts_recent is never updated because we never accept new segments. 448169608Sandre */ 449169608Sandre#endif 450169608Sandre 451169608Sandre /* 452169608Sandre * If a new connection request is received 453169608Sandre * while in TIME_WAIT, drop the old connection 454169608Sandre * and start over if the sequence numbers 455169608Sandre * are above the previous ones. 456169608Sandre */ 457169608Sandre if ((thflags & TH_SYN) && SEQ_GT(th->th_seq, tw->rcv_nxt)) { 458169608Sandre tcp_twclose(tw, 0); 459169608Sandre return (1); 460169608Sandre } 461169608Sandre 462169608Sandre /* 463218909Sbrucec * Drop the segment if it does not contain an ACK. 464169608Sandre */ 465169608Sandre if ((thflags & TH_ACK) == 0) 466169608Sandre goto drop; 467169608Sandre 468169608Sandre /* 469169608Sandre * Reset the 2MSL timer if this is a duplicate FIN. 470169608Sandre */ 471169608Sandre if (thflags & TH_FIN) { 472169608Sandre seq = th->th_seq + tlen + (thflags & TH_SYN ? 1 : 0); 473169608Sandre if (seq + 1 == tw->rcv_nxt) 474169608Sandre tcp_tw_2msl_reset(tw, 1); 475169608Sandre } 476169608Sandre 477169608Sandre /* 478169608Sandre * Acknowledge the segment if it has data or is not a duplicate ACK. 479169608Sandre */ 480169608Sandre if (thflags != TH_ACK || tlen != 0 || 481169608Sandre th->th_seq != tw->rcv_nxt || th->th_ack != tw->snd_nxt) 482169608Sandre tcp_twrespond(tw, TH_ACK); 483169608Sandredrop: 484178285Srwatson INP_WUNLOCK(inp); 485169608Sandre m_freem(m); 486169608Sandre return (0); 487169608Sandre} 488169608Sandre 489157376Srwatsonvoid 490112009Sjlemontcp_twclose(struct tcptw *tw, int reuse) 491111145Sjlemon{ 492157376Srwatson struct socket *so; 493111145Sjlemon struct inpcb *inp; 494111145Sjlemon 495157376Srwatson /* 496157386Srwatson * At this point, we are in one of two situations: 497157376Srwatson * 498160549Srwatson * (1) We have no socket, just an inpcb<->twtcp pair. We can free 499160549Srwatson * all state. 500157386Srwatson * 501160549Srwatson * (2) We have a socket -- if we own a reference, release it and 502160549Srwatson * notify the socket layer. 503157376Srwatson */ 504111145Sjlemon inp = tw->tw_inpcb; 505189848Srwatson KASSERT((inp->inp_flags & INP_TIMEWAIT), ("tcp_twclose: !timewait")); 506157432Srwatson KASSERT(intotw(inp) == tw, ("tcp_twclose: inp_ppcb != tw")); 507309108Sjch INP_INFO_RLOCK_ASSERT(&V_tcbinfo); /* in_pcbfree() */ 508178285Srwatson INP_WLOCK_ASSERT(inp); 509138020Srwatson 510275402Sjch tcp_tw_2msl_stop(tw, reuse); 511111145Sjlemon inp->inp_ppcb = NULL; 512158009Srwatson in_pcbdrop(inp); 513157376Srwatson 514157376Srwatson so = inp->inp_socket; 515157386Srwatson if (so != NULL) { 516160549Srwatson /* 517160549Srwatson * If there's a socket, handle two cases: first, we own a 518160549Srwatson * strong reference, which we will now release, or we don't 519160549Srwatson * in which case another reference exists (XXXRW: think 520160549Srwatson * about this more), and we don't need to take action. 521160549Srwatson */ 522189848Srwatson if (inp->inp_flags & INP_SOCKREF) { 523189848Srwatson inp->inp_flags &= ~INP_SOCKREF; 524178285Srwatson INP_WUNLOCK(inp); 525157386Srwatson ACCEPT_LOCK(); 526157386Srwatson SOCK_LOCK(so); 527157386Srwatson KASSERT(so->so_state & SS_PROTOREF, 528157386Srwatson ("tcp_twclose: INP_SOCKREF && !SS_PROTOREF")); 529157386Srwatson so->so_state &= ~SS_PROTOREF; 530157386Srwatson sofree(so); 531157376Srwatson } else { 532157386Srwatson /* 533157386Srwatson * If we don't own the only reference, the socket and 534157386Srwatson * inpcb need to be left around to be handled by 535157386Srwatson * tcp_usr_detach() later. 536157386Srwatson */ 537178285Srwatson INP_WUNLOCK(inp); 538157376Srwatson } 539275402Sjch } else { 540275402Sjch /* 541275402Sjch * The socket has been already cleaned-up for us, only free the 542275402Sjch * inpcb. 543275402Sjch */ 544185370Sbz in_pcbfree(inp); 545275402Sjch } 546190948Srwatson TCPSTAT_INC(tcps_closed); 547111145Sjlemon} 548111145Sjlemon 549270054Sbzstatic int 550126351Srwatsontcp_twrespond(struct tcptw *tw, int flags) 551111145Sjlemon{ 552111145Sjlemon struct inpcb *inp = tw->tw_inpcb; 553221250Sbz#if defined(INET6) || defined(INET) 554221250Sbz struct tcphdr *th = NULL; 555221250Sbz#endif 556111145Sjlemon struct mbuf *m; 557221250Sbz#ifdef INET 558111145Sjlemon struct ip *ip = NULL; 559221250Sbz#endif 560111145Sjlemon u_int hdrlen, optlen; 561221250Sbz int error = 0; /* Keep compiler happy */ 562168845Sandre struct tcpopt to; 563111145Sjlemon#ifdef INET6 564111145Sjlemon struct ip6_hdr *ip6 = NULL; 565186222Sbz int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6; 566111145Sjlemon#endif 567242854Srdivacky hdrlen = 0; /* Keep compiler happy */ 568111145Sjlemon 569178285Srwatson INP_WLOCK_ASSERT(inp); 570138020Srwatson 571243882Sglebius m = m_gethdr(M_NOWAIT, MT_DATA); 572111145Sjlemon if (m == NULL) 573111145Sjlemon return (ENOBUFS); 574111145Sjlemon m->m_data += max_linkhdr; 575111145Sjlemon 576114794Srwatson#ifdef MAC 577172930Srwatson mac_inpcb_create_mbuf(inp, m); 578114794Srwatson#endif 579114794Srwatson 580111153Sjlemon#ifdef INET6 581111145Sjlemon if (isipv6) { 582111145Sjlemon hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 583111145Sjlemon ip6 = mtod(m, struct ip6_hdr *); 584111145Sjlemon th = (struct tcphdr *)(ip6 + 1); 585111145Sjlemon tcpip_fillheaders(inp, ip6, th); 586221250Sbz } 587111153Sjlemon#endif 588221250Sbz#if defined(INET6) && defined(INET) 589221250Sbz else 590221250Sbz#endif 591221250Sbz#ifdef INET 592111153Sjlemon { 593111145Sjlemon hdrlen = sizeof(struct tcpiphdr); 594111145Sjlemon ip = mtod(m, struct ip *); 595111145Sjlemon th = (struct tcphdr *)(ip + 1); 596111145Sjlemon tcpip_fillheaders(inp, ip, th); 597111145Sjlemon } 598221250Sbz#endif 599168845Sandre to.to_flags = 0; 600133874Srwatson 601133874Srwatson /* 602111145Sjlemon * Send a timestamp and echo-reply if both our side and our peer 603111145Sjlemon * have sent timestamps in our SYN's and this is not a RST. 604133874Srwatson */ 605111145Sjlemon if (tw->t_recent && flags == TH_ACK) { 606168845Sandre to.to_flags |= TOF_TS; 607231767Sbz to.to_tsval = tcp_ts_getticks() + tw->ts_offset; 608168845Sandre to.to_tsecr = tw->t_recent; 609133874Srwatson } 610168845Sandre optlen = tcp_addoptions(&to, (u_char *)(th + 1)); 611111145Sjlemon 612111145Sjlemon m->m_len = hdrlen + optlen; 613111145Sjlemon m->m_pkthdr.len = m->m_len; 614111145Sjlemon 615111145Sjlemon KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small")); 616111145Sjlemon 617111145Sjlemon th->th_seq = htonl(tw->snd_nxt); 618111145Sjlemon th->th_ack = htonl(tw->rcv_nxt); 619111145Sjlemon th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 620111145Sjlemon th->th_flags = flags; 621111145Sjlemon th->th_win = htons(tw->last_win); 622111145Sjlemon 623235961Sbz m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 624111153Sjlemon#ifdef INET6 625111145Sjlemon if (isipv6) { 626236170Sbz m->m_pkthdr.csum_flags = CSUM_TCP_IPV6; 627235961Sbz th->th_sum = in6_cksum_pseudo(ip6, 628235961Sbz sizeof(struct tcphdr) + optlen, IPPROTO_TCP, 0); 629122922Sandre ip6->ip6_hlim = in6_selecthlim(inp, NULL); 630122922Sandre error = ip6_output(m, inp->in6p_outputopts, NULL, 631111145Sjlemon (tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp); 632221250Sbz } 633111153Sjlemon#endif 634221250Sbz#if defined(INET6) && defined(INET) 635221250Sbz else 636221250Sbz#endif 637221250Sbz#ifdef INET 638111153Sjlemon { 639236170Sbz m->m_pkthdr.csum_flags = CSUM_TCP; 640111145Sjlemon th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 641133874Srwatson htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP)); 642241913Sglebius ip->ip_len = htons(m->m_pkthdr.len); 643181803Sbz if (V_path_mtu_discovery) 644241913Sglebius ip->ip_off |= htons(IP_DF); 645122922Sandre error = ip_output(m, inp->inp_options, NULL, 646134793Sjmg ((tw->tw_so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0), 647134793Sjmg NULL, inp); 648111145Sjlemon } 649221250Sbz#endif 650111145Sjlemon if (flags & TH_ACK) 651190948Srwatson TCPSTAT_INC(tcps_sndacks); 652111145Sjlemon else 653190948Srwatson TCPSTAT_INC(tcps_sndctrl); 654190948Srwatson TCPSTAT_INC(tcps_sndtotal); 655111145Sjlemon return (error); 656111145Sjlemon} 657169608Sandre 658169608Sandrestatic void 659169608Sandretcp_tw_2msl_reset(struct tcptw *tw, int rearm) 660169608Sandre{ 661169608Sandre 662309108Sjch INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 663178285Srwatson INP_WLOCK_ASSERT(tw->tw_inpcb); 664275402Sjch 665275402Sjch TW_WLOCK(V_tw_lock); 666169608Sandre if (rearm) 667181803Sbz TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl); 668169608Sandre tw->tw_time = ticks + 2 * tcp_msl; 669181803Sbz TAILQ_INSERT_TAIL(&V_twq_2msl, tw, tw_2msl); 670275402Sjch TW_WUNLOCK(V_tw_lock); 671169608Sandre} 672169608Sandre 673169608Sandrestatic void 674275402Sjchtcp_tw_2msl_stop(struct tcptw *tw, int reuse) 675169608Sandre{ 676275402Sjch struct ucred *cred; 677275402Sjch struct inpcb *inp; 678275402Sjch int released; 679169608Sandre 680309108Sjch INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 681275402Sjch 682275402Sjch TW_WLOCK(V_tw_lock); 683275402Sjch inp = tw->tw_inpcb; 684275402Sjch tw->tw_inpcb = NULL; 685275402Sjch 686181803Sbz TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl); 687275402Sjch cred = tw->tw_cred; 688275402Sjch tw->tw_cred = NULL; 689275402Sjch TW_WUNLOCK(V_tw_lock); 690275402Sjch 691275402Sjch if (cred != NULL) 692275402Sjch crfree(cred); 693275402Sjch 694275402Sjch released = in_pcbrele_wlocked(inp); 695275402Sjch KASSERT(!released, ("%s: inp should not be released here", __func__)); 696275402Sjch 697275402Sjch if (!reuse) 698275402Sjch uma_zfree(V_tcptw_zone, tw); 699169608Sandre} 700169608Sandre 701169608Sandrestruct tcptw * 702169608Sandretcp_tw_2msl_scan(int reuse) 703169608Sandre{ 704169608Sandre struct tcptw *tw; 705275402Sjch struct inpcb *inp; 706169608Sandre 707275402Sjch#ifdef INVARIANTS 708275402Sjch if (reuse) { 709275402Sjch /* 710309108Sjch * Exclusive pcbinfo lock is not required in reuse case even if 711309108Sjch * two inpcb locks can be acquired simultaneously: 712275402Sjch * - the inpcb transitioning to TIME_WAIT state in 713275402Sjch * tcp_tw_start(), 714275402Sjch * - the inpcb closed by tcp_twclose(). 715309108Sjch * 716309108Sjch * It is because only inpcbs in FIN_WAIT2 or CLOSING states can 717309108Sjch * transition in TIME_WAIT state. Then a pcbcb cannot be in 718309108Sjch * TIME_WAIT list and transitioning to TIME_WAIT state at same 719309108Sjch * time. 720275402Sjch */ 721309108Sjch INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 722275402Sjch } 723275402Sjch#endif 724275402Sjch 725169608Sandre for (;;) { 726275402Sjch TW_RLOCK(V_tw_lock); 727181803Sbz tw = TAILQ_FIRST(&V_twq_2msl); 728275402Sjch if (tw == NULL || (!reuse && (tw->tw_time - ticks) > 0)) { 729275402Sjch TW_RUNLOCK(V_tw_lock); 730169608Sandre break; 731275402Sjch } 732275402Sjch KASSERT(tw->tw_inpcb != NULL, ("%s: tw->tw_inpcb == NULL", 733275402Sjch __func__)); 734275402Sjch 735275402Sjch inp = tw->tw_inpcb; 736275402Sjch in_pcbref(inp); 737275402Sjch TW_RUNLOCK(V_tw_lock); 738275402Sjch 739309108Sjch if (INP_INFO_TRY_RLOCK(&V_tcbinfo)) { 740275402Sjch 741275402Sjch INP_WLOCK(inp); 742275402Sjch tw = intotw(inp); 743275402Sjch if (in_pcbrele_wlocked(inp)) { 744275402Sjch KASSERT(tw == NULL, ("%s: held last inp " 745275402Sjch "reference but tw not NULL", __func__)); 746309108Sjch INP_INFO_RUNLOCK(&V_tcbinfo); 747275402Sjch continue; 748275402Sjch } 749275402Sjch 750275402Sjch if (tw == NULL) { 751275402Sjch /* tcp_twclose() has already been called */ 752275402Sjch INP_WUNLOCK(inp); 753309108Sjch INP_INFO_RUNLOCK(&V_tcbinfo); 754275402Sjch continue; 755275402Sjch } 756275402Sjch 757275402Sjch tcp_twclose(tw, reuse); 758309108Sjch INP_INFO_RUNLOCK(&V_tcbinfo); 759275402Sjch if (reuse) 760275402Sjch return tw; 761275402Sjch } else { 762275402Sjch /* INP_INFO lock is busy, continue later. */ 763275402Sjch INP_WLOCK(inp); 764275402Sjch if (!in_pcbrele_wlocked(inp)) 765275402Sjch INP_WUNLOCK(inp); 766275402Sjch break; 767275402Sjch } 768169608Sandre } 769275402Sjch 770275402Sjch return NULL; 771169608Sandre} 772