tcp_input.c revision 281955
1187914Sdes/*- 2187914Sdes * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995 3188604Smckusick * The Regents of the University of California. All rights reserved. 4187914Sdes * Copyright (c) 2007-2008,2010 5187914Sdes * Swinburne University of Technology, Melbourne, Australia. 6187914Sdes * Copyright (c) 2009-2010 Lawrence Stewart <lstewart@freebsd.org> 7187914Sdes * Copyright (c) 2010 The FreeBSD Foundation 8187914Sdes * Copyright (c) 2010-2011 Juniper Networks, Inc. 9187914Sdes * All rights reserved. 10187914Sdes * 11187914Sdes * Portions of this software were developed at the Centre for Advanced Internet 12187914Sdes * Architectures, Swinburne University of Technology, by Lawrence Stewart, 13187914Sdes * James Healy and David Hayes, made possible in part by a grant from the Cisco 14187914Sdes * University Research Program Fund at Community Foundation Silicon Valley. 15187914Sdes * 16187914Sdes * Portions of this software were developed at the Centre for Advanced 17187914Sdes * Internet Architectures, Swinburne University of Technology, Melbourne, 18187914Sdes * Australia by David Hayes under sponsorship from the FreeBSD Foundation. 19187914Sdes * 20187914Sdes * Portions of this software were developed by Robert N. M. Watson under 21187914Sdes * contract to Juniper Networks, Inc. 22187914Sdes * 23187914Sdes * Redistribution and use in source and binary forms, with or without 24187914Sdes * modification, are permitted provided that the following conditions 25187914Sdes * are met: 26187914Sdes * 1. Redistributions of source code must retain the above copyright 27187914Sdes * notice, this list of conditions and the following disclaimer. 28187914Sdes * 2. Redistributions in binary form must reproduce the above copyright 29187914Sdes * notice, this list of conditions and the following disclaimer in the 30187914Sdes * documentation and/or other materials provided with the distribution. 31187914Sdes * 4. Neither the name of the University nor the names of its contributors 32187914Sdes * may be used to endorse or promote products derived from this software 33188568Smckusick * without specific prior written permission. 34187914Sdes * 35187914Sdes * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 36187914Sdes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 37187914Sdes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 38187914Sdes * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 39187914Sdes * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 40188568Smckusick * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 41187914Sdes * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 42187914Sdes * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 43187914Sdes * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 44187914Sdes * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 45188568Smckusick * SUCH DAMAGE. 46187914Sdes * 47187914Sdes * @(#)tcp_input.c 8.12 (Berkeley) 5/24/95 48187914Sdes */ 49187914Sdes 50187914Sdes#include <sys/cdefs.h> 51188604Smckusick__FBSDID("$FreeBSD: stable/10/sys/netinet/tcp_input.c 281955 2015-04-24 23:26:44Z hiren $"); 52197532Sdes 53188604Smckusick#include "opt_ipfw.h" /* for ipfw_fwd */ 54188604Smckusick#include "opt_inet.h" 55197532Sdes#include "opt_inet6.h" 56188604Smckusick#include "opt_ipsec.h" 57188604Smckusick#include "opt_kdtrace.h" 58187914Sdes#include "opt_tcpdebug.h" 59187914Sdes 60188568Smckusick#include <sys/param.h> 61188568Smckusick#include <sys/kernel.h> 62188604Smckusick#include <sys/hhook.h> 63188604Smckusick#include <sys/malloc.h> 64188604Smckusick#include <sys/mbuf.h> 65188604Smckusick#include <sys/proc.h> /* for proc0 declaration */ 66188604Smckusick#include <sys/protosw.h> 67188604Smckusick#include <sys/sdt.h> 68188604Smckusick#include <sys/signalvar.h> 69188604Smckusick#include <sys/socket.h> 70188604Smckusick#include <sys/socketvar.h> 71188604Smckusick#include <sys/sysctl.h> 72188604Smckusick#include <sys/syslog.h> 73188604Smckusick#include <sys/systm.h> 74197532Sdes 75197532Sdes#include <machine/cpu.h> /* before tcp_seq.h, for tcp_random18() */ 76197532Sdes 77197532Sdes#include <vm/uma.h> 78188604Smckusick 79188604Smckusick#include <net/if.h> 80188604Smckusick#include <net/route.h> 81188604Smckusick#include <net/vnet.h> 82188604Smckusick 83188604Smckusick#define TCPSTATES /* for logging */ 84188604Smckusick 85188604Smckusick#include <netinet/cc.h> 86188604Smckusick#include <netinet/in.h> 87229403Sed#include <netinet/in_kdtrace.h> 88188604Smckusick#include <netinet/in_pcb.h> 89188604Smckusick#include <netinet/in_systm.h> 90188604Smckusick#include <netinet/in_var.h> 91188604Smckusick#include <netinet/ip.h> 92188604Smckusick#include <netinet/ip_icmp.h> /* required for icmp_var.h */ 93188604Smckusick#include <netinet/icmp_var.h> /* for ICMP_BANDLIM */ 94188604Smckusick#include <netinet/ip_var.h> 95188604Smckusick#include <netinet/ip_options.h> 96188604Smckusick#include <netinet/ip6.h> 97188604Smckusick#include <netinet/icmp6.h> 98188604Smckusick#include <netinet6/in6_pcb.h> 99188604Smckusick#include <netinet6/ip6_var.h> 100188604Smckusick#include <netinet6/nd6.h> 101188604Smckusick#include <netinet/tcp_fsm.h> 102188604Smckusick#include <netinet/tcp_seq.h> 103188604Smckusick#include <netinet/tcp_timer.h> 104188604Smckusick#include <netinet/tcp_var.h> 105188604Smckusick#include <netinet6/tcp6_var.h> 106188604Smckusick#include <netinet/tcpip.h> 107188604Smckusick#include <netinet/tcp_syncache.h> 108188604Smckusick#ifdef TCPDEBUG 109188604Smckusick#include <netinet/tcp_debug.h> 110188604Smckusick#endif /* TCPDEBUG */ 111188604Smckusick#ifdef TCP_OFFLOAD 112187914Sdes#include <netinet/tcp_offload.h> 113188604Smckusick#endif 114187914Sdes 115187914Sdes#ifdef IPSEC 116187914Sdes#include <netipsec/ipsec.h> 117188604Smckusick#include <netipsec/ipsec6.h> 118197532Sdes#endif /*IPSEC*/ 119188604Smckusick 120187914Sdes#include <machine/in_cksum.h> 121201037Smckusick 122201037Smckusick#include <security/mac/mac_framework.h> 123187914Sdes 124187914Sdesconst int tcprexmtthresh = 3; 125197532Sdes 126188604Smckusickint tcp_log_in_vain = 0; 127300272StruckmanSYSCTL_INT(_net_inet_tcp, OID_AUTO, log_in_vain, CTLFLAG_RW, 128197532Sdes &tcp_log_in_vain, 0, 129197532Sdes "Log all incoming TCP segments to closed ports"); 130197532Sdes 131198265SmckusickVNET_DEFINE(int, blackhole) = 0; 132205207Smckusick#define V_blackhole VNET(blackhole) 133205207SmckusickSYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, blackhole, CTLFLAG_RW, 134188604Smckusick &VNET_NAME(blackhole), 0, 135198265Smckusick "Do not send RST on segments to closed ports"); 136188604Smckusick 137197532SdesVNET_DEFINE(int, tcp_delack_enabled) = 1; 138187914SdesSYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, delayed_ack, CTLFLAG_RW, 139197532Sdes &VNET_NAME(tcp_delack_enabled), 0, 140255007Sjilles "Delay ACK to try and piggyback it onto a data packet"); 141197532Sdes 142197532SdesVNET_DEFINE(int, drop_synfin) = 0; 143188604Smckusick#define V_drop_synfin VNET(drop_synfin) 144188604SmckusickSYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, drop_synfin, CTLFLAG_RW, 145188604Smckusick &VNET_NAME(drop_synfin), 0, 146188604Smckusick "Drop TCP packets with SYN+FIN set"); 147188604Smckusick 148197532SdesVNET_DEFINE(int, tcp_do_rfc3042) = 1; 149188604Smckusick#define V_tcp_do_rfc3042 VNET(tcp_do_rfc3042) 150188604SmckusickSYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, rfc3042, CTLFLAG_RW, 151188604Smckusick &VNET_NAME(tcp_do_rfc3042), 0, 152188604Smckusick "Enable RFC 3042 (Limited Transmit)"); 153188604Smckusick 154188604SmckusickVNET_DEFINE(int, tcp_do_rfc3390) = 1; 155188604SmckusickSYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, rfc3390, CTLFLAG_RW, 156188604Smckusick &VNET_NAME(tcp_do_rfc3390), 0, 157188604Smckusick "Enable RFC 3390 (Increasing TCP's Initial Congestion Window)"); 158188604Smckusick 159188604SmckusickSYSCTL_NODE(_net_inet_tcp, OID_AUTO, experimental, CTLFLAG_RW, 0, 160197532Sdes "Experimental TCP extensions"); 161188604Smckusick 162188604SmckusickVNET_DEFINE(int, tcp_do_initcwnd10) = 1; 163188604SmckusickSYSCTL_VNET_INT(_net_inet_tcp_experimental, OID_AUTO, initcwnd10, CTLFLAG_RW, 164188604Smckusick &VNET_NAME(tcp_do_initcwnd10), 0, 165188604Smckusick "Enable RFC 6928 (Increasing initial CWND to 10)"); 166188604Smckusick 167187914SdesVNET_DEFINE(int, tcp_do_rfc3465) = 1; 168188604SmckusickSYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, rfc3465, CTLFLAG_RW, 169187914Sdes &VNET_NAME(tcp_do_rfc3465), 0, 170197532Sdes "Enable RFC 3465 (Appropriate Byte Counting)"); 171255007Sjilles 172255007SjillesVNET_DEFINE(int, tcp_abc_l_var) = 2; 173197532SdesSYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, abc_l_var, CTLFLAG_RW, 174188604Smckusick &VNET_NAME(tcp_abc_l_var), 2, 175187914Sdes "Cap the max cwnd increment during slow-start to this number of segments"); 176187914Sdes 177187914Sdesstatic SYSCTL_NODE(_net_inet_tcp, OID_AUTO, ecn, CTLFLAG_RW, 0, "TCP ECN"); 178187914Sdes 179187914SdesVNET_DEFINE(int, tcp_do_ecn) = 0; 180201037SmckusickSYSCTL_VNET_INT(_net_inet_tcp_ecn, OID_AUTO, enable, CTLFLAG_RW, 181201037Smckusick &VNET_NAME(tcp_do_ecn), 0, 182201037Smckusick "TCP ECN support"); 183197532Sdes 184201037SmckusickVNET_DEFINE(int, tcp_ecn_maxretries) = 1; 185187914SdesSYSCTL_VNET_INT(_net_inet_tcp_ecn, OID_AUTO, maxretries, CTLFLAG_RW, 186187914Sdes &VNET_NAME(tcp_ecn_maxretries), 0, 187187914Sdes "Max retries before giving up on ECN"); 188187914Sdes 189197532SdesVNET_DEFINE(int, tcp_insecure_rst) = 0; 190197532Sdes#define V_tcp_insecure_rst VNET(tcp_insecure_rst) 191197532SdesSYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, insecure_rst, CTLFLAG_RW, 192201037Smckusick &VNET_NAME(tcp_insecure_rst), 0, 193197532Sdes "Follow the old (insecure) criteria for accepting RST packets"); 194197532Sdes 195197532SdesVNET_DEFINE(int, tcp_recvspace) = 1024*64; 196197532Sdes#define V_tcp_recvspace VNET(tcp_recvspace) 197187914SdesSYSCTL_VNET_INT(_net_inet_tcp, TCPCTL_RECVSPACE, recvspace, CTLFLAG_RW, 198187914Sdes &VNET_NAME(tcp_recvspace), 0, "Initial receive socket buffer size"); 199187914Sdes 200187914SdesVNET_DEFINE(int, tcp_do_autorcvbuf) = 1; 201187914Sdes#define V_tcp_do_autorcvbuf VNET(tcp_do_autorcvbuf) 202187914SdesSYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, recvbuf_auto, CTLFLAG_RW, 203188604Smckusick &VNET_NAME(tcp_do_autorcvbuf), 0, 204188604Smckusick "Enable automatic receive buffer sizing"); 205187914Sdes 206187914SdesVNET_DEFINE(int, tcp_autorcvbuf_inc) = 16*1024; 207187914Sdes#define V_tcp_autorcvbuf_inc VNET(tcp_autorcvbuf_inc) 208199328SmckusickSYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, recvbuf_inc, CTLFLAG_RW, 209199328Smckusick &VNET_NAME(tcp_autorcvbuf_inc), 0, 210199328Smckusick "Incrementor step size of automatic receive buffer"); 211199328Smckusick 212199328SmckusickVNET_DEFINE(int, tcp_autorcvbuf_max) = 2*1024*1024; 213199328Smckusick#define V_tcp_autorcvbuf_max VNET(tcp_autorcvbuf_max) 214199328SmckusickSYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, recvbuf_max, CTLFLAG_RW, 215199328Smckusick &VNET_NAME(tcp_autorcvbuf_max), 0, 216199328Smckusick "Max size of automatic receive buffer"); 217199328Smckusick 218199328SmckusickVNET_DEFINE(struct inpcbhead, tcb); 219199328Smckusick#define tcb6 tcb /* for KAME src sync over BSD*'s */ 220199328SmckusickVNET_DEFINE(struct inpcbinfo, tcbinfo); 221199328Smckusick 222199328Smckusickstatic void tcp_dooptions(struct tcpopt *, u_char *, int, int); 223199328Smckusickstatic void tcp_do_segment(struct mbuf *, struct tcphdr *, 224197532Sdes struct socket *, struct tcpcb *, int, int, uint8_t, 225197532Sdes int); 226197532Sdesstatic void tcp_dropwithreset(struct mbuf *, struct tcphdr *, 227197532Sdes struct tcpcb *, int, int); 228197532Sdesstatic void tcp_pulloutofband(struct socket *, 229197532Sdes struct tcphdr *, struct mbuf *, int); 230197532Sdesstatic void tcp_xmit_timer(struct tcpcb *, int); 231197532Sdesstatic void tcp_newreno_partial_ack(struct tcpcb *, struct tcphdr *); 232197532Sdesstatic void inline cc_ack_received(struct tcpcb *tp, struct tcphdr *th, 233197532Sdes uint16_t type); 234197532Sdesstatic void inline cc_conn_init(struct tcpcb *tp); 235197532Sdesstatic void inline cc_post_recovery(struct tcpcb *tp, struct tcphdr *th); 236197532Sdesstatic void inline hhook_run_tcp_est_in(struct tcpcb *tp, 237197532Sdes struct tcphdr *th, struct tcpopt *to); 238197532Sdes 239197532Sdes/* 240197532Sdes * TCP statistics are stored in an "array" of counter(9)s. 241197532Sdes */ 242197532SdesVNET_PCPUSTAT_DEFINE(struct tcpstat, tcpstat); 243197532SdesVNET_PCPUSTAT_SYSINIT(tcpstat); 244197532SdesSYSCTL_VNET_PCPUSTAT(_net_inet_tcp, TCPCTL_STATS, stats, struct tcpstat, 245197532Sdes tcpstat, "TCP statistics (struct tcpstat, netinet/tcp_var.h)"); 246197532Sdes 247197532Sdes#ifdef VIMAGE 248198265SmckusickVNET_PCPUSTAT_SYSUNINIT(tcpstat); 249198265Smckusick#endif /* VIMAGE */ 250198265Smckusick/* 251198265Smckusick * Kernel module interface for updating tcpstat. The argument is an index 252205207Smckusick * into tcpstat treated as an array. 253198265Smckusick */ 254198265Smckusickvoid 255198265Smckusickkmod_tcpstat_inc(int statnum) 256198265Smckusick{ 257198265Smckusick 258205207Smckusick counter_u64_add(VNET(tcpstat)[statnum], 1); 259205207Smckusick} 260198265Smckusick 261205207Smckusick/* 262205207Smckusick * Wrapper for the TCP established input helper hook. 263198265Smckusick */ 264205207Smckusickstatic void inline 265205207Smckusickhhook_run_tcp_est_in(struct tcpcb *tp, struct tcphdr *th, struct tcpopt *to) 266198265Smckusick{ 267205207Smckusick struct tcp_hhook_data hhook_data; 268198265Smckusick 269198265Smckusick if (V_tcp_hhh[HHOOK_TCP_EST_IN]->hhh_nhooks > 0) { 270187914Sdes hhook_data.tp = tp; 271187914Sdes hhook_data.th = th; 272187914Sdes hhook_data.to = to; 273187914Sdes 274187914Sdes hhook_run_hooks(V_tcp_hhh[HHOOK_TCP_EST_IN], &hhook_data, 275187914Sdes tp->osd); 276187914Sdes } 277187914Sdes} 278187914Sdes 279187914Sdes/* 280187914Sdes * CC wrapper hook functions 281198265Smckusick */ 282187914Sdesstatic void inline 283187914Sdescc_ack_received(struct tcpcb *tp, struct tcphdr *th, uint16_t type) 284187914Sdes{ 285187914Sdes INP_WLOCK_ASSERT(tp->t_inpcb); 286187914Sdes 287187914Sdes tp->ccv->bytes_this_ack = BYTES_THIS_ACK(tp, th); 288187914Sdes if (tp->snd_cwnd <= tp->snd_wnd) 289187914Sdes tp->ccv->flags |= CCF_CWND_LIMITED; 290187914Sdes else 291187914Sdes tp->ccv->flags &= ~CCF_CWND_LIMITED; 292187914Sdes 293187914Sdes if (type == CC_ACK) { 294187914Sdes if (tp->snd_cwnd > tp->snd_ssthresh) { 295187914Sdes tp->t_bytes_acked += min(tp->ccv->bytes_this_ack, 296187914Sdes V_tcp_abc_l_var * tp->t_maxseg); 297187914Sdes if (tp->t_bytes_acked >= tp->snd_cwnd) { 298187914Sdes tp->t_bytes_acked -= tp->snd_cwnd; 299187914Sdes tp->ccv->flags |= CCF_ABC_SENTAWND; 300187914Sdes } 301187914Sdes } else { 302187914Sdes tp->ccv->flags &= ~CCF_ABC_SENTAWND; 303187914Sdes tp->t_bytes_acked = 0; 304187914Sdes } 305187914Sdes } 306187914Sdes 307187914Sdes if (CC_ALGO(tp)->ack_received != NULL) { 308187914Sdes /* XXXLAS: Find a way to live without this */ 309198265Smckusick tp->ccv->curack = th->th_ack; 310187914Sdes CC_ALGO(tp)->ack_received(tp->ccv, type); 311187914Sdes } 312187914Sdes} 313187914Sdes 314187914Sdesstatic void inline 315187914Sdescc_conn_init(struct tcpcb *tp) 316187914Sdes{ 317187914Sdes struct hc_metrics_lite metrics; 318187914Sdes struct inpcb *inp = tp->t_inpcb; 319187914Sdes int rtt; 320187914Sdes 321187914Sdes INP_WLOCK_ASSERT(tp->t_inpcb); 322187914Sdes 323187914Sdes tcp_hc_get(&inp->inp_inc, &metrics); 324187914Sdes 325187914Sdes if (tp->t_srtt == 0 && (rtt = metrics.rmx_rtt)) { 326187914Sdes tp->t_srtt = rtt; 327187914Sdes tp->t_rttbest = tp->t_srtt + TCP_RTT_SCALE; 328187914Sdes TCPSTAT_INC(tcps_usedrtt); 329188604Smckusick if (metrics.rmx_rttvar) { 330187914Sdes tp->t_rttvar = metrics.rmx_rttvar; 331188604Smckusick TCPSTAT_INC(tcps_usedrttvar); 332188604Smckusick } else { 333188604Smckusick /* default variation is +- 1 rtt */ 334188604Smckusick tp->t_rttvar = 335188604Smckusick tp->t_srtt * TCP_RTTVAR_SCALE / TCP_RTT_SCALE; 336187914Sdes } 337197510Sdes TCPT_RANGESET(tp->t_rxtcur, 338187914Sdes ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1, 339197510Sdes tp->t_rttmin, TCPTV_REXMTMAX); 340187914Sdes } 341187914Sdes if (metrics.rmx_ssthresh) { 342187914Sdes /* 343187914Sdes * There's some sort of gateway or interface 344187914Sdes * buffer limit on the path. Use this to set 345187914Sdes * the slow start threshhold, but set the 346187914Sdes * threshold to no less than 2*mss. 347187914Sdes */ 348187914Sdes tp->snd_ssthresh = max(2 * tp->t_maxseg, metrics.rmx_ssthresh); 349187914Sdes TCPSTAT_INC(tcps_usedssthresh); 350187914Sdes } 351187914Sdes 352187914Sdes /* 353187914Sdes * Set the initial slow-start flight size. 354187914Sdes * 355187914Sdes * RFC5681 Section 3.1 specifies the default conservative values. 356187914Sdes * RFC3390 specifies slightly more aggressive values. 357187914Sdes * RFC6928 increases it to ten segments. 358187914Sdes * 359187914Sdes * If a SYN or SYN/ACK was lost and retransmitted, we have to 360187914Sdes * reduce the initial CWND to one segment as congestion is likely 361187914Sdes * requiring us to be cautious. 362187914Sdes */ 363187914Sdes if (tp->snd_cwnd == 1) 364187914Sdes tp->snd_cwnd = tp->t_maxseg; /* SYN(-ACK) lost */ 365187914Sdes else if (V_tcp_do_initcwnd10) 366187914Sdes tp->snd_cwnd = min(10 * tp->t_maxseg, 367188604Smckusick max(2 * tp->t_maxseg, 14600)); 368188604Smckusick else if (V_tcp_do_rfc3390) 369188604Smckusick tp->snd_cwnd = min(4 * tp->t_maxseg, 370187914Sdes max(2 * tp->t_maxseg, 4380)); 371187914Sdes else { 372187914Sdes /* Per RFC5681 Section 3.1 */ 373187914Sdes if (tp->t_maxseg > 2190) 374187914Sdes tp->snd_cwnd = 2 * tp->t_maxseg; 375187914Sdes else if (tp->t_maxseg > 1095) 376187914Sdes tp->snd_cwnd = 3 * tp->t_maxseg; 377187914Sdes else 378187914Sdes tp->snd_cwnd = 4 * tp->t_maxseg; 379187914Sdes } 380187914Sdes 381187914Sdes if (CC_ALGO(tp)->conn_init != NULL) 382187914Sdes CC_ALGO(tp)->conn_init(tp->ccv); 383187914Sdes} 384187914Sdes 385187914Sdesvoid inline 386187914Sdescc_cong_signal(struct tcpcb *tp, struct tcphdr *th, uint32_t type) 387187914Sdes{ 388187914Sdes INP_WLOCK_ASSERT(tp->t_inpcb); 389187914Sdes 390188604Smckusick switch(type) { 391188604Smckusick case CC_NDUPACK: 392188604Smckusick if (!IN_FASTRECOVERY(tp->t_flags)) { 393187914Sdes tp->snd_recover = tp->snd_max; 394187914Sdes if (tp->t_flags & TF_ECN_PERMIT) 395187914Sdes tp->t_flags |= TF_ECN_SND_CWR; 396188604Smckusick } 397187914Sdes break; 398188604Smckusick case CC_ECN: 399188604Smckusick if (!IN_CONGRECOVERY(tp->t_flags)) { 400187914Sdes TCPSTAT_INC(tcps_ecn_rcwnd); 401188604Smckusick tp->snd_recover = tp->snd_max; 402188604Smckusick if (tp->t_flags & TF_ECN_PERMIT) 403188604Smckusick tp->t_flags |= TF_ECN_SND_CWR; 404188604Smckusick } 405188604Smckusick break; 406188604Smckusick case CC_RTO: 407188604Smckusick tp->t_dupacks = 0; 408205207Smckusick tp->t_bytes_acked = 0; 409205207Smckusick EXIT_RECOVERY(tp->t_flags); 410205207Smckusick tp->snd_ssthresh = max(2, min(tp->snd_wnd, tp->snd_cwnd) / 2 / 411205207Smckusick tp->t_maxseg) * tp->t_maxseg; 412188604Smckusick tp->snd_cwnd = tp->t_maxseg; 413188604Smckusick break; 414188604Smckusick case CC_RTO_ERR: 415188604Smckusick TCPSTAT_INC(tcps_sndrexmitbad); 416188604Smckusick /* RTO was unnecessary, so reset everything. */ 417188604Smckusick tp->snd_cwnd = tp->snd_cwnd_prev; 418188604Smckusick tp->snd_ssthresh = tp->snd_ssthresh_prev; 419188604Smckusick tp->snd_recover = tp->snd_recover_prev; 420188604Smckusick if (tp->t_flags & TF_WASFRECOVERY) 421188604Smckusick ENTER_FASTRECOVERY(tp->t_flags); 422188604Smckusick if (tp->t_flags & TF_WASCRECOVERY) 423188604Smckusick ENTER_CONGRECOVERY(tp->t_flags); 424188604Smckusick tp->snd_nxt = tp->snd_max; 425188604Smckusick tp->t_flags &= ~TF_PREVVALID; 426188604Smckusick tp->t_badrxtwin = 0; 427188604Smckusick break; 428188604Smckusick } 429188604Smckusick 430188604Smckusick if (CC_ALGO(tp)->cong_signal != NULL) { 431188604Smckusick if (th != NULL) 432187914Sdes tp->ccv->curack = th->th_ack; 433197510Sdes CC_ALGO(tp)->cong_signal(tp->ccv, type); 434187914Sdes } 435197510Sdes} 436187914Sdes 437187914Sdesstatic void inline 438187914Sdescc_post_recovery(struct tcpcb *tp, struct tcphdr *th) 439187914Sdes{ 440187914Sdes INP_WLOCK_ASSERT(tp->t_inpcb); 441187914Sdes 442188568Smckusick /* XXXLAS: KASSERT that we're in recovery? */ 443188568Smckusick 444188604Smckusick if (CC_ALGO(tp)->post_recovery != NULL) { 445188568Smckusick tp->ccv->curack = th->th_ack; 446188604Smckusick CC_ALGO(tp)->post_recovery(tp->ccv); 447188604Smckusick } 448188568Smckusick /* XXXLAS: EXIT_RECOVERY ? */ 449188604Smckusick tp->t_bytes_acked = 0; 450188604Smckusick} 451188604Smckusick 452188568Smckusick#ifdef TCP_SIGNATURE 453188568Smckusickstatic inline int 454188604Smckusicktcp_signature_verify_input(struct mbuf *m, int off0, int tlen, int optlen, 455188568Smckusick struct tcpopt *to, struct tcphdr *th, u_int tcpbflag) 456205207Smckusick{ 457205207Smckusick int ret; 458205207Smckusick 459205207Smckusick tcp_fields_to_net(th); 460188604Smckusick ret = tcp_signature_verify(m, off0, tlen, optlen, to, th, tcpbflag); 461188604Smckusick tcp_fields_to_host(th); 462188604Smckusick return (ret); 463188604Smckusick} 464188604Smckusick#endif 465188604Smckusick 466188604Smckusick/* Neighbor Discovery, Neighbor Unreachability Detection Upper layer hint. */ 467188604Smckusick#ifdef INET6 468188604Smckusick#define ND6_HINT(tp) \ 469188604Smckusickdo { \ 470188604Smckusick if ((tp) && (tp)->t_inpcb && \ 471188604Smckusick ((tp)->t_inpcb->inp_vflag & INP_IPV6) != 0) \ 472188604Smckusick nd6_nud_hint(NULL, NULL, 0); \ 473188604Smckusick} while (0) 474188604Smckusick#else 475188604Smckusick#define ND6_HINT(tp) 476188604Smckusick#endif 477188604Smckusick 478188604Smckusick/* 479188604Smckusick * Indicate whether this ack should be delayed. We can delay the ack if 480188604Smckusick * - there is no delayed ack timer in progress and 481188604Smckusick * - our last ack wasn't a 0-sized window. We never want to delay 482188604Smckusick * the ack that opens up a 0-sized window and 483188604Smckusick * - delayed acks are enabled or 484188604Smckusick * - this is a half-synchronized T/TCP connection. 485188604Smckusick * - the segment size is not larger than the MSS and LRO wasn't used 486188604Smckusick * for this segment. 487188604Smckusick */ 488188604Smckusick#define DELAY_ACK(tp, tlen) \ 489188604Smckusick ((!tcp_timer_active(tp, TT_DELACK) && \ 490188604Smckusick (tp->t_flags & TF_RXWIN0SENT) == 0) && \ 491197510Sdes (tlen <= tp->t_maxopd) && \ 492188604Smckusick (V_tcp_delack_enabled || (tp->t_flags & TF_NEEDSYN))) 493197510Sdes 494188604Smckusick/* 495188604Smckusick * TCP input handling is split into multiple parts: 496188604Smckusick * tcp6_input is a thin wrapper around tcp_input for the extended 497188568Smckusick * ip6_protox[] call format in ip6_input 498188604Smckusick * tcp_input handles primary segment validation, inpcb lookup and 499188568Smckusick * SYN processing on listen sockets 500201144Smckusick * tcp_do_segment processes the ACK and text of the segment for 501201144Smckusick * establishing, established and closing connections 502201144Smckusick */ 503201144Smckusick#ifdef INET6 504201144Smckusickint 505201144Smckusicktcp6_input(struct mbuf **mp, int *offp, int proto) 506201144Smckusick{ 507201144Smckusick struct mbuf *m = *mp; 508201144Smckusick struct in6_ifaddr *ia6; 509201144Smckusick 510201144Smckusick IP6_EXTHDR_CHECK(m, *offp, sizeof(struct tcphdr), IPPROTO_DONE); 511201144Smckusick 512201144Smckusick /* 513201144Smckusick * draft-itojun-ipv6-tcp-to-anycast 514201144Smckusick * better place to put this in? 515201144Smckusick */ 516201144Smckusick ia6 = ip6_getdstifaddr(m); 517201144Smckusick if (ia6 && (ia6->ia6_flags & IN6_IFF_ANYCAST)) { 518201144Smckusick struct ip6_hdr *ip6; 519201144Smckusick 520201144Smckusick ifa_free(&ia6->ia_ifa); 521201144Smckusick ip6 = mtod(m, struct ip6_hdr *); 522201144Smckusick icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR, 523201144Smckusick (caddr_t)&ip6->ip6_dst - (caddr_t)ip6); 524201144Smckusick return IPPROTO_DONE; 525201144Smckusick } 526201144Smckusick if (ia6) 527201144Smckusick ifa_free(&ia6->ia_ifa); 528201144Smckusick 529201144Smckusick tcp_input(m, *offp); 530201144Smckusick return IPPROTO_DONE; 531201144Smckusick} 532201144Smckusick#endif /* INET6 */ 533201144Smckusick 534201144Smckusickvoid 535201144Smckusicktcp_input(struct mbuf *m, int off0) 536201144Smckusick{ 537201144Smckusick struct tcphdr *th = NULL; 538255007Sjilles struct ip *ip = NULL; 539255007Sjilles struct inpcb *inp = NULL; 540201144Smckusick struct tcpcb *tp = NULL; 541201144Smckusick struct socket *so = NULL; 542201144Smckusick u_char *optp = NULL; 543201144Smckusick int optlen = 0; 544201144Smckusick#ifdef INET 545201144Smckusick int len; 546201144Smckusick#endif 547201144Smckusick int tlen = 0, off; 548201144Smckusick int drop_hdrlen; 549201144Smckusick int thflags; 550201144Smckusick int rstreason = 0; /* For badport_bandlim accounting purposes */ 551201144Smckusick#ifdef TCP_SIGNATURE 552201144Smckusick uint8_t sig_checked = 0; 553201144Smckusick#endif 554201144Smckusick uint8_t iptos = 0; 555201144Smckusick struct m_tag *fwd_tag = NULL; 556201144Smckusick#ifdef INET6 557201144Smckusick struct ip6_hdr *ip6 = NULL; 558201144Smckusick int isipv6; 559201144Smckusick#else 560201144Smckusick const void *ip6 = NULL; 561201144Smckusick#endif /* INET6 */ 562201144Smckusick struct tcpopt to; /* options in this segment */ 563201144Smckusick char *s = NULL; /* address and port logging */ 564201144Smckusick int ti_locked; 565201144Smckusick#define TI_UNLOCKED 1 566201144Smckusick#define TI_WLOCKED 2 567201144Smckusick 568201144Smckusick#ifdef TCPDEBUG 569201144Smckusick /* 570201144Smckusick * The size of tcp_saveipgen must be the size of the max ip header, 571201144Smckusick * now IPv6. 572201144Smckusick */ 573201144Smckusick u_char tcp_saveipgen[IP6_HDR_LEN]; 574201144Smckusick struct tcphdr tcp_savetcp; 575201144Smckusick short ostate = 0; 576201144Smckusick#endif 577201144Smckusick 578201144Smckusick#ifdef INET6 579201144Smckusick isipv6 = (mtod(m, struct ip *)->ip_v == 6) ? 1 : 0; 580201144Smckusick#endif 581201144Smckusick 582201144Smckusick to.to_flags = 0; 583201144Smckusick TCPSTAT_INC(tcps_rcvtotal); 584201144Smckusick 585201144Smckusick#ifdef INET6 586201144Smckusick if (isipv6) { 587201144Smckusick /* IP6_EXTHDR_CHECK() is already done at tcp6_input(). */ 588201144Smckusick 589201144Smckusick if (m->m_len < (sizeof(*ip6) + sizeof(*th))) { 590201144Smckusick m = m_pullup(m, sizeof(*ip6) + sizeof(*th)); 591201144Smckusick if (m == NULL) { 592201144Smckusick TCPSTAT_INC(tcps_rcvshort); 593201144Smckusick return; 594201144Smckusick } 595201144Smckusick } 596 597 ip6 = mtod(m, struct ip6_hdr *); 598 th = (struct tcphdr *)((caddr_t)ip6 + off0); 599 tlen = sizeof(*ip6) + ntohs(ip6->ip6_plen) - off0; 600 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID_IPV6) { 601 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 602 th->th_sum = m->m_pkthdr.csum_data; 603 else 604 th->th_sum = in6_cksum_pseudo(ip6, tlen, 605 IPPROTO_TCP, m->m_pkthdr.csum_data); 606 th->th_sum ^= 0xffff; 607 } else 608 th->th_sum = in6_cksum(m, IPPROTO_TCP, off0, tlen); 609 if (th->th_sum) { 610 TCPSTAT_INC(tcps_rcvbadsum); 611 goto drop; 612 } 613 614 /* 615 * Be proactive about unspecified IPv6 address in source. 616 * As we use all-zero to indicate unbounded/unconnected pcb, 617 * unspecified IPv6 address can be used to confuse us. 618 * 619 * Note that packets with unspecified IPv6 destination is 620 * already dropped in ip6_input. 621 */ 622 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 623 /* XXX stat */ 624 goto drop; 625 } 626 } 627#endif 628#if defined(INET) && defined(INET6) 629 else 630#endif 631#ifdef INET 632 { 633 /* 634 * Get IP and TCP header together in first mbuf. 635 * Note: IP leaves IP header in first mbuf. 636 */ 637 if (off0 > sizeof (struct ip)) { 638 ip_stripoptions(m); 639 off0 = sizeof(struct ip); 640 } 641 if (m->m_len < sizeof (struct tcpiphdr)) { 642 if ((m = m_pullup(m, sizeof (struct tcpiphdr))) 643 == NULL) { 644 TCPSTAT_INC(tcps_rcvshort); 645 return; 646 } 647 } 648 ip = mtod(m, struct ip *); 649 th = (struct tcphdr *)((caddr_t)ip + off0); 650 tlen = ntohs(ip->ip_len) - off0; 651 652 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) { 653 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 654 th->th_sum = m->m_pkthdr.csum_data; 655 else 656 th->th_sum = in_pseudo(ip->ip_src.s_addr, 657 ip->ip_dst.s_addr, 658 htonl(m->m_pkthdr.csum_data + tlen + 659 IPPROTO_TCP)); 660 th->th_sum ^= 0xffff; 661 } else { 662 struct ipovly *ipov = (struct ipovly *)ip; 663 664 /* 665 * Checksum extended TCP header and data. 666 */ 667 len = off0 + tlen; 668 bzero(ipov->ih_x1, sizeof(ipov->ih_x1)); 669 ipov->ih_len = htons(tlen); 670 th->th_sum = in_cksum(m, len); 671 /* Reset length for SDT probes. */ 672 ip->ip_len = htons(tlen + off0); 673 } 674 675 if (th->th_sum) { 676 TCPSTAT_INC(tcps_rcvbadsum); 677 goto drop; 678 } 679 /* Re-initialization for later version check */ 680 ip->ip_v = IPVERSION; 681 } 682#endif /* INET */ 683 684#ifdef INET6 685 if (isipv6) 686 iptos = (ntohl(ip6->ip6_flow) >> 20) & 0xff; 687#endif 688#if defined(INET) && defined(INET6) 689 else 690#endif 691#ifdef INET 692 iptos = ip->ip_tos; 693#endif 694 695 /* 696 * Check that TCP offset makes sense, 697 * pull out TCP options and adjust length. XXX 698 */ 699 off = th->th_off << 2; 700 if (off < sizeof (struct tcphdr) || off > tlen) { 701 TCPSTAT_INC(tcps_rcvbadoff); 702 goto drop; 703 } 704 tlen -= off; /* tlen is used instead of ti->ti_len */ 705 if (off > sizeof (struct tcphdr)) { 706#ifdef INET6 707 if (isipv6) { 708 IP6_EXTHDR_CHECK(m, off0, off, ); 709 ip6 = mtod(m, struct ip6_hdr *); 710 th = (struct tcphdr *)((caddr_t)ip6 + off0); 711 } 712#endif 713#if defined(INET) && defined(INET6) 714 else 715#endif 716#ifdef INET 717 { 718 if (m->m_len < sizeof(struct ip) + off) { 719 if ((m = m_pullup(m, sizeof (struct ip) + off)) 720 == NULL) { 721 TCPSTAT_INC(tcps_rcvshort); 722 return; 723 } 724 ip = mtod(m, struct ip *); 725 th = (struct tcphdr *)((caddr_t)ip + off0); 726 } 727 } 728#endif 729 optlen = off - sizeof (struct tcphdr); 730 optp = (u_char *)(th + 1); 731 } 732 thflags = th->th_flags; 733 734 /* 735 * Convert TCP protocol specific fields to host format. 736 */ 737 tcp_fields_to_host(th); 738 739 /* 740 * Delay dropping TCP, IP headers, IPv6 ext headers, and TCP options. 741 */ 742 drop_hdrlen = off0 + off; 743 744 /* 745 * Locate pcb for segment; if we're likely to add or remove a 746 * connection then first acquire pcbinfo lock. There are two cases 747 * where we might discover later we need a write lock despite the 748 * flags: ACKs moving a connection out of the syncache, and ACKs for 749 * a connection in TIMEWAIT. 750 */ 751 if ((thflags & (TH_SYN | TH_FIN | TH_RST)) != 0) { 752 INP_INFO_WLOCK(&V_tcbinfo); 753 ti_locked = TI_WLOCKED; 754 } else 755 ti_locked = TI_UNLOCKED; 756 757 /* 758 * Grab info from PACKET_TAG_IPFORWARD tag prepended to the chain. 759 */ 760 if ( 761#ifdef INET6 762 (isipv6 && (m->m_flags & M_IP6_NEXTHOP)) 763#ifdef INET 764 || (!isipv6 && (m->m_flags & M_IP_NEXTHOP)) 765#endif 766#endif 767#if defined(INET) && !defined(INET6) 768 (m->m_flags & M_IP_NEXTHOP) 769#endif 770 ) 771 fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL); 772 773findpcb: 774#ifdef INVARIANTS 775 if (ti_locked == TI_WLOCKED) { 776 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 777 } else { 778 INP_INFO_UNLOCK_ASSERT(&V_tcbinfo); 779 } 780#endif 781#ifdef INET6 782 if (isipv6 && fwd_tag != NULL) { 783 struct sockaddr_in6 *next_hop6; 784 785 next_hop6 = (struct sockaddr_in6 *)(fwd_tag + 1); 786 /* 787 * Transparently forwarded. Pretend to be the destination. 788 * Already got one like this? 789 */ 790 inp = in6_pcblookup_mbuf(&V_tcbinfo, 791 &ip6->ip6_src, th->th_sport, &ip6->ip6_dst, th->th_dport, 792 INPLOOKUP_WLOCKPCB, m->m_pkthdr.rcvif, m); 793 if (!inp) { 794 /* 795 * It's new. Try to find the ambushing socket. 796 * Because we've rewritten the destination address, 797 * any hardware-generated hash is ignored. 798 */ 799 inp = in6_pcblookup(&V_tcbinfo, &ip6->ip6_src, 800 th->th_sport, &next_hop6->sin6_addr, 801 next_hop6->sin6_port ? ntohs(next_hop6->sin6_port) : 802 th->th_dport, INPLOOKUP_WILDCARD | 803 INPLOOKUP_WLOCKPCB, m->m_pkthdr.rcvif); 804 } 805 } else if (isipv6) { 806 inp = in6_pcblookup_mbuf(&V_tcbinfo, &ip6->ip6_src, 807 th->th_sport, &ip6->ip6_dst, th->th_dport, 808 INPLOOKUP_WILDCARD | INPLOOKUP_WLOCKPCB, 809 m->m_pkthdr.rcvif, m); 810 } 811#endif /* INET6 */ 812#if defined(INET6) && defined(INET) 813 else 814#endif 815#ifdef INET 816 if (fwd_tag != NULL) { 817 struct sockaddr_in *next_hop; 818 819 next_hop = (struct sockaddr_in *)(fwd_tag+1); 820 /* 821 * Transparently forwarded. Pretend to be the destination. 822 * already got one like this? 823 */ 824 inp = in_pcblookup_mbuf(&V_tcbinfo, ip->ip_src, th->th_sport, 825 ip->ip_dst, th->th_dport, INPLOOKUP_WLOCKPCB, 826 m->m_pkthdr.rcvif, m); 827 if (!inp) { 828 /* 829 * It's new. Try to find the ambushing socket. 830 * Because we've rewritten the destination address, 831 * any hardware-generated hash is ignored. 832 */ 833 inp = in_pcblookup(&V_tcbinfo, ip->ip_src, 834 th->th_sport, next_hop->sin_addr, 835 next_hop->sin_port ? ntohs(next_hop->sin_port) : 836 th->th_dport, INPLOOKUP_WILDCARD | 837 INPLOOKUP_WLOCKPCB, m->m_pkthdr.rcvif); 838 } 839 } else 840 inp = in_pcblookup_mbuf(&V_tcbinfo, ip->ip_src, 841 th->th_sport, ip->ip_dst, th->th_dport, 842 INPLOOKUP_WILDCARD | INPLOOKUP_WLOCKPCB, 843 m->m_pkthdr.rcvif, m); 844#endif /* INET */ 845 846 /* 847 * If the INPCB does not exist then all data in the incoming 848 * segment is discarded and an appropriate RST is sent back. 849 * XXX MRT Send RST using which routing table? 850 */ 851 if (inp == NULL) { 852 /* 853 * Log communication attempts to ports that are not 854 * in use. 855 */ 856 if ((tcp_log_in_vain == 1 && (thflags & TH_SYN)) || 857 tcp_log_in_vain == 2) { 858 if ((s = tcp_log_vain(NULL, th, (void *)ip, ip6))) 859 log(LOG_INFO, "%s; %s: Connection attempt " 860 "to closed port\n", s, __func__); 861 } 862 /* 863 * When blackholing do not respond with a RST but 864 * completely ignore the segment and drop it. 865 */ 866 if ((V_blackhole == 1 && (thflags & TH_SYN)) || 867 V_blackhole == 2) 868 goto dropunlock; 869 870 rstreason = BANDLIM_RST_CLOSEDPORT; 871 goto dropwithreset; 872 } 873 INP_WLOCK_ASSERT(inp); 874 if ((inp->inp_flowtype == M_HASHTYPE_NONE) && 875 (M_HASHTYPE_GET(m) != M_HASHTYPE_NONE) && 876 ((inp->inp_socket == NULL) || 877 (inp->inp_socket->so_options & SO_ACCEPTCONN) == 0)) { 878 inp->inp_flowid = m->m_pkthdr.flowid; 879 } 880#ifdef IPSEC 881#ifdef INET6 882 if (isipv6 && ipsec6_in_reject(m, inp)) { 883 IPSEC6STAT_INC(ips_in_polvio); 884 goto dropunlock; 885 } else 886#endif /* INET6 */ 887 if (ipsec4_in_reject(m, inp) != 0) { 888 IPSECSTAT_INC(ips_in_polvio); 889 goto dropunlock; 890 } 891#endif /* IPSEC */ 892 893 /* 894 * Check the minimum TTL for socket. 895 */ 896 if (inp->inp_ip_minttl != 0) { 897#ifdef INET6 898 if (isipv6 && inp->inp_ip_minttl > ip6->ip6_hlim) 899 goto dropunlock; 900 else 901#endif 902 if (inp->inp_ip_minttl > ip->ip_ttl) 903 goto dropunlock; 904 } 905 906 /* 907 * A previous connection in TIMEWAIT state is supposed to catch stray 908 * or duplicate segments arriving late. If this segment was a 909 * legitimate new connection attempt, the old INPCB gets removed and 910 * we can try again to find a listening socket. 911 * 912 * At this point, due to earlier optimism, we may hold only an inpcb 913 * lock, and not the inpcbinfo write lock. If so, we need to try to 914 * acquire it, or if that fails, acquire a reference on the inpcb, 915 * drop all locks, acquire a global write lock, and then re-acquire 916 * the inpcb lock. We may at that point discover that another thread 917 * has tried to free the inpcb, in which case we need to loop back 918 * and try to find a new inpcb to deliver to. 919 * 920 * XXXRW: It may be time to rethink timewait locking. 921 */ 922relocked: 923 if (inp->inp_flags & INP_TIMEWAIT) { 924 if (ti_locked == TI_UNLOCKED) { 925 if (INP_INFO_TRY_WLOCK(&V_tcbinfo) == 0) { 926 in_pcbref(inp); 927 INP_WUNLOCK(inp); 928 INP_INFO_WLOCK(&V_tcbinfo); 929 ti_locked = TI_WLOCKED; 930 INP_WLOCK(inp); 931 if (in_pcbrele_wlocked(inp)) { 932 inp = NULL; 933 goto findpcb; 934 } 935 } else 936 ti_locked = TI_WLOCKED; 937 } 938 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 939 940 if (thflags & TH_SYN) 941 tcp_dooptions(&to, optp, optlen, TO_SYN); 942 /* 943 * NB: tcp_twcheck unlocks the INP and frees the mbuf. 944 */ 945 if (tcp_twcheck(inp, &to, th, m, tlen)) 946 goto findpcb; 947 INP_INFO_WUNLOCK(&V_tcbinfo); 948 return; 949 } 950 /* 951 * The TCPCB may no longer exist if the connection is winding 952 * down or it is in the CLOSED state. Either way we drop the 953 * segment and send an appropriate response. 954 */ 955 tp = intotcpcb(inp); 956 if (tp == NULL || tp->t_state == TCPS_CLOSED) { 957 rstreason = BANDLIM_RST_CLOSEDPORT; 958 goto dropwithreset; 959 } 960 961#ifdef TCP_OFFLOAD 962 if (tp->t_flags & TF_TOE) { 963 tcp_offload_input(tp, m); 964 m = NULL; /* consumed by the TOE driver */ 965 goto dropunlock; 966 } 967#endif 968 969 /* 970 * We've identified a valid inpcb, but it could be that we need an 971 * inpcbinfo write lock but don't hold it. In this case, attempt to 972 * acquire using the same strategy as the TIMEWAIT case above. If we 973 * relock, we have to jump back to 'relocked' as the connection might 974 * now be in TIMEWAIT. 975 */ 976#ifdef INVARIANTS 977 if ((thflags & (TH_SYN | TH_FIN | TH_RST)) != 0) 978 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 979#endif 980 if (tp->t_state != TCPS_ESTABLISHED) { 981 if (ti_locked == TI_UNLOCKED) { 982 if (INP_INFO_TRY_WLOCK(&V_tcbinfo) == 0) { 983 in_pcbref(inp); 984 INP_WUNLOCK(inp); 985 INP_INFO_WLOCK(&V_tcbinfo); 986 ti_locked = TI_WLOCKED; 987 INP_WLOCK(inp); 988 if (in_pcbrele_wlocked(inp)) { 989 inp = NULL; 990 goto findpcb; 991 } 992 goto relocked; 993 } else 994 ti_locked = TI_WLOCKED; 995 } 996 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 997 } 998 999#ifdef MAC 1000 INP_WLOCK_ASSERT(inp); 1001 if (mac_inpcb_check_deliver(inp, m)) 1002 goto dropunlock; 1003#endif 1004 so = inp->inp_socket; 1005 KASSERT(so != NULL, ("%s: so == NULL", __func__)); 1006#ifdef TCPDEBUG 1007 if (so->so_options & SO_DEBUG) { 1008 ostate = tp->t_state; 1009#ifdef INET6 1010 if (isipv6) { 1011 bcopy((char *)ip6, (char *)tcp_saveipgen, sizeof(*ip6)); 1012 } else 1013#endif 1014 bcopy((char *)ip, (char *)tcp_saveipgen, sizeof(*ip)); 1015 tcp_savetcp = *th; 1016 } 1017#endif /* TCPDEBUG */ 1018 /* 1019 * When the socket is accepting connections (the INPCB is in LISTEN 1020 * state) we look into the SYN cache if this is a new connection 1021 * attempt or the completion of a previous one. Because listen 1022 * sockets are never in TCPS_ESTABLISHED, the V_tcbinfo lock will be 1023 * held in this case. 1024 */ 1025 if (so->so_options & SO_ACCEPTCONN) { 1026 struct in_conninfo inc; 1027 1028 KASSERT(tp->t_state == TCPS_LISTEN, ("%s: so accepting but " 1029 "tp not listening", __func__)); 1030 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 1031 1032 bzero(&inc, sizeof(inc)); 1033#ifdef INET6 1034 if (isipv6) { 1035 inc.inc_flags |= INC_ISIPV6; 1036 inc.inc6_faddr = ip6->ip6_src; 1037 inc.inc6_laddr = ip6->ip6_dst; 1038 } else 1039#endif 1040 { 1041 inc.inc_faddr = ip->ip_src; 1042 inc.inc_laddr = ip->ip_dst; 1043 } 1044 inc.inc_fport = th->th_sport; 1045 inc.inc_lport = th->th_dport; 1046 inc.inc_fibnum = so->so_fibnum; 1047 1048 /* 1049 * Check for an existing connection attempt in syncache if 1050 * the flag is only ACK. A successful lookup creates a new 1051 * socket appended to the listen queue in SYN_RECEIVED state. 1052 */ 1053 if ((thflags & (TH_RST|TH_ACK|TH_SYN)) == TH_ACK) { 1054 /* 1055 * Parse the TCP options here because 1056 * syncookies need access to the reflected 1057 * timestamp. 1058 */ 1059 tcp_dooptions(&to, optp, optlen, 0); 1060 /* 1061 * NB: syncache_expand() doesn't unlock 1062 * inp and tcpinfo locks. 1063 */ 1064 if (!syncache_expand(&inc, &to, th, &so, m)) { 1065 /* 1066 * No syncache entry or ACK was not 1067 * for our SYN/ACK. Send a RST. 1068 * NB: syncache did its own logging 1069 * of the failure cause. 1070 */ 1071 rstreason = BANDLIM_RST_OPENPORT; 1072 goto dropwithreset; 1073 } 1074 if (so == NULL) { 1075 /* 1076 * We completed the 3-way handshake 1077 * but could not allocate a socket 1078 * either due to memory shortage, 1079 * listen queue length limits or 1080 * global socket limits. Send RST 1081 * or wait and have the remote end 1082 * retransmit the ACK for another 1083 * try. 1084 */ 1085 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1086 log(LOG_DEBUG, "%s; %s: Listen socket: " 1087 "Socket allocation failed due to " 1088 "limits or memory shortage, %s\n", 1089 s, __func__, 1090 V_tcp_sc_rst_sock_fail ? 1091 "sending RST" : "try again"); 1092 if (V_tcp_sc_rst_sock_fail) { 1093 rstreason = BANDLIM_UNLIMITED; 1094 goto dropwithreset; 1095 } else 1096 goto dropunlock; 1097 } 1098 /* 1099 * Socket is created in state SYN_RECEIVED. 1100 * Unlock the listen socket, lock the newly 1101 * created socket and update the tp variable. 1102 */ 1103 INP_WUNLOCK(inp); /* listen socket */ 1104 inp = sotoinpcb(so); 1105 INP_WLOCK(inp); /* new connection */ 1106 tp = intotcpcb(inp); 1107 KASSERT(tp->t_state == TCPS_SYN_RECEIVED, 1108 ("%s: ", __func__)); 1109#ifdef TCP_SIGNATURE 1110 if (sig_checked == 0) { 1111 tcp_dooptions(&to, optp, optlen, 1112 (thflags & TH_SYN) ? TO_SYN : 0); 1113 if (!tcp_signature_verify_input(m, off0, tlen, 1114 optlen, &to, th, tp->t_flags)) { 1115 1116 /* 1117 * In SYN_SENT state if it receives an 1118 * RST, it is allowed for further 1119 * processing. 1120 */ 1121 if ((thflags & TH_RST) == 0 || 1122 (tp->t_state == TCPS_SYN_SENT) == 0) 1123 goto dropunlock; 1124 } 1125 sig_checked = 1; 1126 } 1127#endif 1128 1129 /* 1130 * Process the segment and the data it 1131 * contains. tcp_do_segment() consumes 1132 * the mbuf chain and unlocks the inpcb. 1133 */ 1134 tcp_do_segment(m, th, so, tp, drop_hdrlen, tlen, 1135 iptos, ti_locked); 1136 INP_INFO_UNLOCK_ASSERT(&V_tcbinfo); 1137 return; 1138 } 1139 /* 1140 * Segment flag validation for new connection attempts: 1141 * 1142 * Our (SYN|ACK) response was rejected. 1143 * Check with syncache and remove entry to prevent 1144 * retransmits. 1145 * 1146 * NB: syncache_chkrst does its own logging of failure 1147 * causes. 1148 */ 1149 if (thflags & TH_RST) { 1150 syncache_chkrst(&inc, th); 1151 goto dropunlock; 1152 } 1153 /* 1154 * We can't do anything without SYN. 1155 */ 1156 if ((thflags & TH_SYN) == 0) { 1157 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1158 log(LOG_DEBUG, "%s; %s: Listen socket: " 1159 "SYN is missing, segment ignored\n", 1160 s, __func__); 1161 TCPSTAT_INC(tcps_badsyn); 1162 goto dropunlock; 1163 } 1164 /* 1165 * (SYN|ACK) is bogus on a listen socket. 1166 */ 1167 if (thflags & TH_ACK) { 1168 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1169 log(LOG_DEBUG, "%s; %s: Listen socket: " 1170 "SYN|ACK invalid, segment rejected\n", 1171 s, __func__); 1172 syncache_badack(&inc); /* XXX: Not needed! */ 1173 TCPSTAT_INC(tcps_badsyn); 1174 rstreason = BANDLIM_RST_OPENPORT; 1175 goto dropwithreset; 1176 } 1177 /* 1178 * If the drop_synfin option is enabled, drop all 1179 * segments with both the SYN and FIN bits set. 1180 * This prevents e.g. nmap from identifying the 1181 * TCP/IP stack. 1182 * XXX: Poor reasoning. nmap has other methods 1183 * and is constantly refining its stack detection 1184 * strategies. 1185 * XXX: This is a violation of the TCP specification 1186 * and was used by RFC1644. 1187 */ 1188 if ((thflags & TH_FIN) && V_drop_synfin) { 1189 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1190 log(LOG_DEBUG, "%s; %s: Listen socket: " 1191 "SYN|FIN segment ignored (based on " 1192 "sysctl setting)\n", s, __func__); 1193 TCPSTAT_INC(tcps_badsyn); 1194 goto dropunlock; 1195 } 1196 /* 1197 * Segment's flags are (SYN) or (SYN|FIN). 1198 * 1199 * TH_PUSH, TH_URG, TH_ECE, TH_CWR are ignored 1200 * as they do not affect the state of the TCP FSM. 1201 * The data pointed to by TH_URG and th_urp is ignored. 1202 */ 1203 KASSERT((thflags & (TH_RST|TH_ACK)) == 0, 1204 ("%s: Listen socket: TH_RST or TH_ACK set", __func__)); 1205 KASSERT(thflags & (TH_SYN), 1206 ("%s: Listen socket: TH_SYN not set", __func__)); 1207#ifdef INET6 1208 /* 1209 * If deprecated address is forbidden, 1210 * we do not accept SYN to deprecated interface 1211 * address to prevent any new inbound connection from 1212 * getting established. 1213 * When we do not accept SYN, we send a TCP RST, 1214 * with deprecated source address (instead of dropping 1215 * it). We compromise it as it is much better for peer 1216 * to send a RST, and RST will be the final packet 1217 * for the exchange. 1218 * 1219 * If we do not forbid deprecated addresses, we accept 1220 * the SYN packet. RFC2462 does not suggest dropping 1221 * SYN in this case. 1222 * If we decipher RFC2462 5.5.4, it says like this: 1223 * 1. use of deprecated addr with existing 1224 * communication is okay - "SHOULD continue to be 1225 * used" 1226 * 2. use of it with new communication: 1227 * (2a) "SHOULD NOT be used if alternate address 1228 * with sufficient scope is available" 1229 * (2b) nothing mentioned otherwise. 1230 * Here we fall into (2b) case as we have no choice in 1231 * our source address selection - we must obey the peer. 1232 * 1233 * The wording in RFC2462 is confusing, and there are 1234 * multiple description text for deprecated address 1235 * handling - worse, they are not exactly the same. 1236 * I believe 5.5.4 is the best one, so we follow 5.5.4. 1237 */ 1238 if (isipv6 && !V_ip6_use_deprecated) { 1239 struct in6_ifaddr *ia6; 1240 1241 ia6 = ip6_getdstifaddr(m); 1242 if (ia6 != NULL && 1243 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) { 1244 ifa_free(&ia6->ia_ifa); 1245 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1246 log(LOG_DEBUG, "%s; %s: Listen socket: " 1247 "Connection attempt to deprecated " 1248 "IPv6 address rejected\n", 1249 s, __func__); 1250 rstreason = BANDLIM_RST_OPENPORT; 1251 goto dropwithreset; 1252 } 1253 if (ia6) 1254 ifa_free(&ia6->ia_ifa); 1255 } 1256#endif /* INET6 */ 1257 /* 1258 * Basic sanity checks on incoming SYN requests: 1259 * Don't respond if the destination is a link layer 1260 * broadcast according to RFC1122 4.2.3.10, p. 104. 1261 * If it is from this socket it must be forged. 1262 * Don't respond if the source or destination is a 1263 * global or subnet broad- or multicast address. 1264 * Note that it is quite possible to receive unicast 1265 * link-layer packets with a broadcast IP address. Use 1266 * in_broadcast() to find them. 1267 */ 1268 if (m->m_flags & (M_BCAST|M_MCAST)) { 1269 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1270 log(LOG_DEBUG, "%s; %s: Listen socket: " 1271 "Connection attempt from broad- or multicast " 1272 "link layer address ignored\n", s, __func__); 1273 goto dropunlock; 1274 } 1275#ifdef INET6 1276 if (isipv6) { 1277 if (th->th_dport == th->th_sport && 1278 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &ip6->ip6_src)) { 1279 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1280 log(LOG_DEBUG, "%s; %s: Listen socket: " 1281 "Connection attempt to/from self " 1282 "ignored\n", s, __func__); 1283 goto dropunlock; 1284 } 1285 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 1286 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) { 1287 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1288 log(LOG_DEBUG, "%s; %s: Listen socket: " 1289 "Connection attempt from/to multicast " 1290 "address ignored\n", s, __func__); 1291 goto dropunlock; 1292 } 1293 } 1294#endif 1295#if defined(INET) && defined(INET6) 1296 else 1297#endif 1298#ifdef INET 1299 { 1300 if (th->th_dport == th->th_sport && 1301 ip->ip_dst.s_addr == ip->ip_src.s_addr) { 1302 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1303 log(LOG_DEBUG, "%s; %s: Listen socket: " 1304 "Connection attempt from/to self " 1305 "ignored\n", s, __func__); 1306 goto dropunlock; 1307 } 1308 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 1309 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 1310 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || 1311 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) { 1312 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1313 log(LOG_DEBUG, "%s; %s: Listen socket: " 1314 "Connection attempt from/to broad- " 1315 "or multicast address ignored\n", 1316 s, __func__); 1317 goto dropunlock; 1318 } 1319 } 1320#endif 1321 /* 1322 * SYN appears to be valid. Create compressed TCP state 1323 * for syncache. 1324 */ 1325#ifdef TCPDEBUG 1326 if (so->so_options & SO_DEBUG) 1327 tcp_trace(TA_INPUT, ostate, tp, 1328 (void *)tcp_saveipgen, &tcp_savetcp, 0); 1329#endif 1330 tcp_dooptions(&to, optp, optlen, TO_SYN); 1331 syncache_add(&inc, &to, th, inp, &so, m, NULL, NULL); 1332 /* 1333 * Entry added to syncache and mbuf consumed. 1334 * Everything already unlocked by syncache_add(). 1335 */ 1336 INP_INFO_UNLOCK_ASSERT(&V_tcbinfo); 1337 return; 1338 } else if (tp->t_state == TCPS_LISTEN) { 1339 /* 1340 * When a listen socket is torn down the SO_ACCEPTCONN 1341 * flag is removed first while connections are drained 1342 * from the accept queue in a unlock/lock cycle of the 1343 * ACCEPT_LOCK, opening a race condition allowing a SYN 1344 * attempt go through unhandled. 1345 */ 1346 goto dropunlock; 1347 } 1348 1349#ifdef TCP_SIGNATURE 1350 if (sig_checked == 0) { 1351 tcp_dooptions(&to, optp, optlen, 1352 (thflags & TH_SYN) ? TO_SYN : 0); 1353 if (!tcp_signature_verify_input(m, off0, tlen, optlen, &to, 1354 th, tp->t_flags)) { 1355 1356 /* 1357 * In SYN_SENT state if it receives an RST, it is 1358 * allowed for further processing. 1359 */ 1360 if ((thflags & TH_RST) == 0 || 1361 (tp->t_state == TCPS_SYN_SENT) == 0) 1362 goto dropunlock; 1363 } 1364 sig_checked = 1; 1365 } 1366#endif 1367 1368 TCP_PROBE5(receive, NULL, tp, mtod(m, const char *), tp, th); 1369 1370 /* 1371 * Segment belongs to a connection in SYN_SENT, ESTABLISHED or later 1372 * state. tcp_do_segment() always consumes the mbuf chain, unlocks 1373 * the inpcb, and unlocks pcbinfo. 1374 */ 1375 tcp_do_segment(m, th, so, tp, drop_hdrlen, tlen, iptos, ti_locked); 1376 INP_INFO_UNLOCK_ASSERT(&V_tcbinfo); 1377 return; 1378 1379dropwithreset: 1380 TCP_PROBE5(receive, NULL, tp, mtod(m, const char *), tp, th); 1381 1382 if (ti_locked == TI_WLOCKED) { 1383 INP_INFO_WUNLOCK(&V_tcbinfo); 1384 ti_locked = TI_UNLOCKED; 1385 } 1386#ifdef INVARIANTS 1387 else { 1388 KASSERT(ti_locked == TI_UNLOCKED, ("%s: dropwithreset " 1389 "ti_locked: %d", __func__, ti_locked)); 1390 INP_INFO_UNLOCK_ASSERT(&V_tcbinfo); 1391 } 1392#endif 1393 1394 if (inp != NULL) { 1395 tcp_dropwithreset(m, th, tp, tlen, rstreason); 1396 INP_WUNLOCK(inp); 1397 } else 1398 tcp_dropwithreset(m, th, NULL, tlen, rstreason); 1399 m = NULL; /* mbuf chain got consumed. */ 1400 goto drop; 1401 1402dropunlock: 1403 if (m != NULL) 1404 TCP_PROBE5(receive, NULL, tp, mtod(m, const char *), tp, th); 1405 1406 if (ti_locked == TI_WLOCKED) { 1407 INP_INFO_WUNLOCK(&V_tcbinfo); 1408 ti_locked = TI_UNLOCKED; 1409 } 1410#ifdef INVARIANTS 1411 else { 1412 KASSERT(ti_locked == TI_UNLOCKED, ("%s: dropunlock " 1413 "ti_locked: %d", __func__, ti_locked)); 1414 INP_INFO_UNLOCK_ASSERT(&V_tcbinfo); 1415 } 1416#endif 1417 1418 if (inp != NULL) 1419 INP_WUNLOCK(inp); 1420 1421drop: 1422 INP_INFO_UNLOCK_ASSERT(&V_tcbinfo); 1423 if (s != NULL) 1424 free(s, M_TCPLOG); 1425 if (m != NULL) 1426 m_freem(m); 1427} 1428 1429static void 1430tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so, 1431 struct tcpcb *tp, int drop_hdrlen, int tlen, uint8_t iptos, 1432 int ti_locked) 1433{ 1434 int thflags, acked, ourfinisacked, needoutput = 0; 1435 int rstreason, todrop, win; 1436 u_long tiwin; 1437 char *s; 1438 struct in_conninfo *inc; 1439 struct mbuf *mfree; 1440 struct tcpopt to; 1441 1442#ifdef TCPDEBUG 1443 /* 1444 * The size of tcp_saveipgen must be the size of the max ip header, 1445 * now IPv6. 1446 */ 1447 u_char tcp_saveipgen[IP6_HDR_LEN]; 1448 struct tcphdr tcp_savetcp; 1449 short ostate = 0; 1450#endif 1451 thflags = th->th_flags; 1452 inc = &tp->t_inpcb->inp_inc; 1453 tp->sackhint.last_sack_ack = 0; 1454 1455 /* 1456 * If this is either a state-changing packet or current state isn't 1457 * established, we require a write lock on tcbinfo. Otherwise, we 1458 * allow the tcbinfo to be in either alocked or unlocked, as the 1459 * caller may have unnecessarily acquired a write lock due to a race. 1460 */ 1461 if ((thflags & (TH_SYN | TH_FIN | TH_RST)) != 0 || 1462 tp->t_state != TCPS_ESTABLISHED) { 1463 KASSERT(ti_locked == TI_WLOCKED, ("%s ti_locked %d for " 1464 "SYN/FIN/RST/!EST", __func__, ti_locked)); 1465 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 1466 } else { 1467#ifdef INVARIANTS 1468 if (ti_locked == TI_WLOCKED) 1469 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 1470 else { 1471 KASSERT(ti_locked == TI_UNLOCKED, ("%s: EST " 1472 "ti_locked: %d", __func__, ti_locked)); 1473 INP_INFO_UNLOCK_ASSERT(&V_tcbinfo); 1474 } 1475#endif 1476 } 1477 INP_WLOCK_ASSERT(tp->t_inpcb); 1478 KASSERT(tp->t_state > TCPS_LISTEN, ("%s: TCPS_LISTEN", 1479 __func__)); 1480 KASSERT(tp->t_state != TCPS_TIME_WAIT, ("%s: TCPS_TIME_WAIT", 1481 __func__)); 1482 1483 /* 1484 * Segment received on connection. 1485 * Reset idle time and keep-alive timer. 1486 * XXX: This should be done after segment 1487 * validation to ignore broken/spoofed segs. 1488 */ 1489 tp->t_rcvtime = ticks; 1490 if (TCPS_HAVEESTABLISHED(tp->t_state)) 1491 tcp_timer_activate(tp, TT_KEEP, TP_KEEPIDLE(tp)); 1492 1493 /* 1494 * Unscale the window into a 32-bit value. 1495 * For the SYN_SENT state the scale is zero. 1496 */ 1497 tiwin = th->th_win << tp->snd_scale; 1498 1499 /* 1500 * TCP ECN processing. 1501 */ 1502 if (tp->t_flags & TF_ECN_PERMIT) { 1503 if (thflags & TH_CWR) 1504 tp->t_flags &= ~TF_ECN_SND_ECE; 1505 switch (iptos & IPTOS_ECN_MASK) { 1506 case IPTOS_ECN_CE: 1507 tp->t_flags |= TF_ECN_SND_ECE; 1508 TCPSTAT_INC(tcps_ecn_ce); 1509 break; 1510 case IPTOS_ECN_ECT0: 1511 TCPSTAT_INC(tcps_ecn_ect0); 1512 break; 1513 case IPTOS_ECN_ECT1: 1514 TCPSTAT_INC(tcps_ecn_ect1); 1515 break; 1516 } 1517 /* Congestion experienced. */ 1518 if (thflags & TH_ECE) { 1519 cc_cong_signal(tp, th, CC_ECN); 1520 } 1521 } 1522 1523 /* 1524 * Parse options on any incoming segment. 1525 */ 1526 tcp_dooptions(&to, (u_char *)(th + 1), 1527 (th->th_off << 2) - sizeof(struct tcphdr), 1528 (thflags & TH_SYN) ? TO_SYN : 0); 1529 1530 /* 1531 * If echoed timestamp is later than the current time, 1532 * fall back to non RFC1323 RTT calculation. Normalize 1533 * timestamp if syncookies were used when this connection 1534 * was established. 1535 */ 1536 if ((to.to_flags & TOF_TS) && (to.to_tsecr != 0)) { 1537 to.to_tsecr -= tp->ts_offset; 1538 if (TSTMP_GT(to.to_tsecr, tcp_ts_getticks())) 1539 to.to_tsecr = 0; 1540 } 1541 /* 1542 * If timestamps were negotiated during SYN/ACK they should 1543 * appear on every segment during this session and vice versa. 1544 */ 1545 if ((tp->t_flags & TF_RCVD_TSTMP) && !(to.to_flags & TOF_TS)) { 1546 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1547 log(LOG_DEBUG, "%s; %s: Timestamp missing, " 1548 "no action\n", s, __func__); 1549 free(s, M_TCPLOG); 1550 } 1551 } 1552 if (!(tp->t_flags & TF_RCVD_TSTMP) && (to.to_flags & TOF_TS)) { 1553 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1554 log(LOG_DEBUG, "%s; %s: Timestamp not expected, " 1555 "no action\n", s, __func__); 1556 free(s, M_TCPLOG); 1557 } 1558 } 1559 1560 /* 1561 * Process options only when we get SYN/ACK back. The SYN case 1562 * for incoming connections is handled in tcp_syncache. 1563 * According to RFC1323 the window field in a SYN (i.e., a <SYN> 1564 * or <SYN,ACK>) segment itself is never scaled. 1565 * XXX this is traditional behavior, may need to be cleaned up. 1566 */ 1567 if (tp->t_state == TCPS_SYN_SENT && (thflags & TH_SYN)) { 1568 if ((to.to_flags & TOF_SCALE) && 1569 (tp->t_flags & TF_REQ_SCALE)) { 1570 tp->t_flags |= TF_RCVD_SCALE; 1571 tp->snd_scale = to.to_wscale; 1572 } 1573 /* 1574 * Initial send window. It will be updated with 1575 * the next incoming segment to the scaled value. 1576 */ 1577 tp->snd_wnd = th->th_win; 1578 if (to.to_flags & TOF_TS) { 1579 tp->t_flags |= TF_RCVD_TSTMP; 1580 tp->ts_recent = to.to_tsval; 1581 tp->ts_recent_age = tcp_ts_getticks(); 1582 } 1583 if (to.to_flags & TOF_MSS) 1584 tcp_mss(tp, to.to_mss); 1585 if ((tp->t_flags & TF_SACK_PERMIT) && 1586 (to.to_flags & TOF_SACKPERM) == 0) 1587 tp->t_flags &= ~TF_SACK_PERMIT; 1588 } 1589 1590 /* 1591 * Header prediction: check for the two common cases 1592 * of a uni-directional data xfer. If the packet has 1593 * no control flags, is in-sequence, the window didn't 1594 * change and we're not retransmitting, it's a 1595 * candidate. If the length is zero and the ack moved 1596 * forward, we're the sender side of the xfer. Just 1597 * free the data acked & wake any higher level process 1598 * that was blocked waiting for space. If the length 1599 * is non-zero and the ack didn't move, we're the 1600 * receiver side. If we're getting packets in-order 1601 * (the reassembly queue is empty), add the data to 1602 * the socket buffer and note that we need a delayed ack. 1603 * Make sure that the hidden state-flags are also off. 1604 * Since we check for TCPS_ESTABLISHED first, it can only 1605 * be TH_NEEDSYN. 1606 */ 1607 if (tp->t_state == TCPS_ESTABLISHED && 1608 th->th_seq == tp->rcv_nxt && 1609 (thflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK && 1610 tp->snd_nxt == tp->snd_max && 1611 tiwin && tiwin == tp->snd_wnd && 1612 ((tp->t_flags & (TF_NEEDSYN|TF_NEEDFIN)) == 0) && 1613 LIST_EMPTY(&tp->t_segq) && 1614 ((to.to_flags & TOF_TS) == 0 || 1615 TSTMP_GEQ(to.to_tsval, tp->ts_recent)) ) { 1616 1617 /* 1618 * If last ACK falls within this segment's sequence numbers, 1619 * record the timestamp. 1620 * NOTE that the test is modified according to the latest 1621 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 1622 */ 1623 if ((to.to_flags & TOF_TS) != 0 && 1624 SEQ_LEQ(th->th_seq, tp->last_ack_sent)) { 1625 tp->ts_recent_age = tcp_ts_getticks(); 1626 tp->ts_recent = to.to_tsval; 1627 } 1628 1629 if (tlen == 0) { 1630 if (SEQ_GT(th->th_ack, tp->snd_una) && 1631 SEQ_LEQ(th->th_ack, tp->snd_max) && 1632 !IN_RECOVERY(tp->t_flags) && 1633 (to.to_flags & TOF_SACK) == 0 && 1634 TAILQ_EMPTY(&tp->snd_holes)) { 1635 /* 1636 * This is a pure ack for outstanding data. 1637 */ 1638 if (ti_locked == TI_WLOCKED) 1639 INP_INFO_WUNLOCK(&V_tcbinfo); 1640 ti_locked = TI_UNLOCKED; 1641 1642 TCPSTAT_INC(tcps_predack); 1643 1644 /* 1645 * "bad retransmit" recovery. 1646 */ 1647 if (tp->t_rxtshift == 1 && 1648 tp->t_flags & TF_PREVVALID && 1649 (int)(ticks - tp->t_badrxtwin) < 0) { 1650 cc_cong_signal(tp, th, CC_RTO_ERR); 1651 } 1652 1653 /* 1654 * Recalculate the transmit timer / rtt. 1655 * 1656 * Some boxes send broken timestamp replies 1657 * during the SYN+ACK phase, ignore 1658 * timestamps of 0 or we could calculate a 1659 * huge RTT and blow up the retransmit timer. 1660 */ 1661 if ((to.to_flags & TOF_TS) != 0 && 1662 to.to_tsecr) { 1663 u_int t; 1664 1665 t = tcp_ts_getticks() - to.to_tsecr; 1666 if (!tp->t_rttlow || tp->t_rttlow > t) 1667 tp->t_rttlow = t; 1668 tcp_xmit_timer(tp, 1669 TCP_TS_TO_TICKS(t) + 1); 1670 } else if (tp->t_rtttime && 1671 SEQ_GT(th->th_ack, tp->t_rtseq)) { 1672 if (!tp->t_rttlow || 1673 tp->t_rttlow > ticks - tp->t_rtttime) 1674 tp->t_rttlow = ticks - tp->t_rtttime; 1675 tcp_xmit_timer(tp, 1676 ticks - tp->t_rtttime); 1677 } 1678 acked = BYTES_THIS_ACK(tp, th); 1679 1680 /* Run HHOOK_TCP_ESTABLISHED_IN helper hooks. */ 1681 hhook_run_tcp_est_in(tp, th, &to); 1682 1683 TCPSTAT_INC(tcps_rcvackpack); 1684 TCPSTAT_ADD(tcps_rcvackbyte, acked); 1685 sbdrop(&so->so_snd, acked); 1686 if (SEQ_GT(tp->snd_una, tp->snd_recover) && 1687 SEQ_LEQ(th->th_ack, tp->snd_recover)) 1688 tp->snd_recover = th->th_ack - 1; 1689 1690 /* 1691 * Let the congestion control algorithm update 1692 * congestion control related information. This 1693 * typically means increasing the congestion 1694 * window. 1695 */ 1696 cc_ack_received(tp, th, CC_ACK); 1697 1698 tp->snd_una = th->th_ack; 1699 /* 1700 * Pull snd_wl2 up to prevent seq wrap relative 1701 * to th_ack. 1702 */ 1703 tp->snd_wl2 = th->th_ack; 1704 tp->t_dupacks = 0; 1705 m_freem(m); 1706 ND6_HINT(tp); /* Some progress has been made. */ 1707 1708 /* 1709 * If all outstanding data are acked, stop 1710 * retransmit timer, otherwise restart timer 1711 * using current (possibly backed-off) value. 1712 * If process is waiting for space, 1713 * wakeup/selwakeup/signal. If data 1714 * are ready to send, let tcp_output 1715 * decide between more output or persist. 1716 */ 1717#ifdef TCPDEBUG 1718 if (so->so_options & SO_DEBUG) 1719 tcp_trace(TA_INPUT, ostate, tp, 1720 (void *)tcp_saveipgen, 1721 &tcp_savetcp, 0); 1722#endif 1723 if (tp->snd_una == tp->snd_max) 1724 tcp_timer_activate(tp, TT_REXMT, 0); 1725 else if (!tcp_timer_active(tp, TT_PERSIST)) 1726 tcp_timer_activate(tp, TT_REXMT, 1727 tp->t_rxtcur); 1728 sowwakeup(so); 1729 if (so->so_snd.sb_cc) 1730 (void) tcp_output(tp); 1731 goto check_delack; 1732 } 1733 } else if (th->th_ack == tp->snd_una && 1734 tlen <= sbspace(&so->so_rcv)) { 1735 int newsize = 0; /* automatic sockbuf scaling */ 1736 1737 /* 1738 * This is a pure, in-sequence data packet with 1739 * nothing on the reassembly queue and we have enough 1740 * buffer space to take it. 1741 */ 1742 if (ti_locked == TI_WLOCKED) 1743 INP_INFO_WUNLOCK(&V_tcbinfo); 1744 ti_locked = TI_UNLOCKED; 1745 1746 /* Clean receiver SACK report if present */ 1747 if ((tp->t_flags & TF_SACK_PERMIT) && tp->rcv_numsacks) 1748 tcp_clean_sackreport(tp); 1749 TCPSTAT_INC(tcps_preddat); 1750 tp->rcv_nxt += tlen; 1751 /* 1752 * Pull snd_wl1 up to prevent seq wrap relative to 1753 * th_seq. 1754 */ 1755 tp->snd_wl1 = th->th_seq; 1756 /* 1757 * Pull rcv_up up to prevent seq wrap relative to 1758 * rcv_nxt. 1759 */ 1760 tp->rcv_up = tp->rcv_nxt; 1761 TCPSTAT_INC(tcps_rcvpack); 1762 TCPSTAT_ADD(tcps_rcvbyte, tlen); 1763 ND6_HINT(tp); /* Some progress has been made */ 1764#ifdef TCPDEBUG 1765 if (so->so_options & SO_DEBUG) 1766 tcp_trace(TA_INPUT, ostate, tp, 1767 (void *)tcp_saveipgen, &tcp_savetcp, 0); 1768#endif 1769 /* 1770 * Automatic sizing of receive socket buffer. Often the send 1771 * buffer size is not optimally adjusted to the actual network 1772 * conditions at hand (delay bandwidth product). Setting the 1773 * buffer size too small limits throughput on links with high 1774 * bandwidth and high delay (eg. trans-continental/oceanic links). 1775 * 1776 * On the receive side the socket buffer memory is only rarely 1777 * used to any significant extent. This allows us to be much 1778 * more aggressive in scaling the receive socket buffer. For 1779 * the case that the buffer space is actually used to a large 1780 * extent and we run out of kernel memory we can simply drop 1781 * the new segments; TCP on the sender will just retransmit it 1782 * later. Setting the buffer size too big may only consume too 1783 * much kernel memory if the application doesn't read() from 1784 * the socket or packet loss or reordering makes use of the 1785 * reassembly queue. 1786 * 1787 * The criteria to step up the receive buffer one notch are: 1788 * 1. the number of bytes received during the time it takes 1789 * one timestamp to be reflected back to us (the RTT); 1790 * 2. received bytes per RTT is within seven eighth of the 1791 * current socket buffer size; 1792 * 3. receive buffer size has not hit maximal automatic size; 1793 * 1794 * This algorithm does one step per RTT at most and only if 1795 * we receive a bulk stream w/o packet losses or reorderings. 1796 * Shrinking the buffer during idle times is not necessary as 1797 * it doesn't consume any memory when idle. 1798 * 1799 * TODO: Only step up if the application is actually serving 1800 * the buffer to better manage the socket buffer resources. 1801 */ 1802 if (V_tcp_do_autorcvbuf && 1803 to.to_tsecr && 1804 (so->so_rcv.sb_flags & SB_AUTOSIZE)) { 1805 if (TSTMP_GT(to.to_tsecr, tp->rfbuf_ts) && 1806 to.to_tsecr - tp->rfbuf_ts < hz) { 1807 if (tp->rfbuf_cnt > 1808 (so->so_rcv.sb_hiwat / 8 * 7) && 1809 so->so_rcv.sb_hiwat < 1810 V_tcp_autorcvbuf_max) { 1811 newsize = 1812 min(so->so_rcv.sb_hiwat + 1813 V_tcp_autorcvbuf_inc, 1814 V_tcp_autorcvbuf_max); 1815 } 1816 /* Start over with next RTT. */ 1817 tp->rfbuf_ts = 0; 1818 tp->rfbuf_cnt = 0; 1819 } else 1820 tp->rfbuf_cnt += tlen; /* add up */ 1821 } 1822 1823 /* Add data to socket buffer. */ 1824 SOCKBUF_LOCK(&so->so_rcv); 1825 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 1826 m_freem(m); 1827 } else { 1828 /* 1829 * Set new socket buffer size. 1830 * Give up when limit is reached. 1831 */ 1832 if (newsize) 1833 if (!sbreserve_locked(&so->so_rcv, 1834 newsize, so, NULL)) 1835 so->so_rcv.sb_flags &= ~SB_AUTOSIZE; 1836 m_adj(m, drop_hdrlen); /* delayed header drop */ 1837 sbappendstream_locked(&so->so_rcv, m); 1838 } 1839 /* NB: sorwakeup_locked() does an implicit unlock. */ 1840 sorwakeup_locked(so); 1841 if (DELAY_ACK(tp, tlen)) { 1842 tp->t_flags |= TF_DELACK; 1843 } else { 1844 tp->t_flags |= TF_ACKNOW; 1845 tcp_output(tp); 1846 } 1847 goto check_delack; 1848 } 1849 } 1850 1851 /* 1852 * Calculate amount of space in receive window, 1853 * and then do TCP input processing. 1854 * Receive window is amount of space in rcv queue, 1855 * but not less than advertised window. 1856 */ 1857 win = sbspace(&so->so_rcv); 1858 if (win < 0) 1859 win = 0; 1860 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 1861 1862 /* Reset receive buffer auto scaling when not in bulk receive mode. */ 1863 tp->rfbuf_ts = 0; 1864 tp->rfbuf_cnt = 0; 1865 1866 switch (tp->t_state) { 1867 1868 /* 1869 * If the state is SYN_RECEIVED: 1870 * if seg contains an ACK, but not for our SYN/ACK, send a RST. 1871 */ 1872 case TCPS_SYN_RECEIVED: 1873 if ((thflags & TH_ACK) && 1874 (SEQ_LEQ(th->th_ack, tp->snd_una) || 1875 SEQ_GT(th->th_ack, tp->snd_max))) { 1876 rstreason = BANDLIM_RST_OPENPORT; 1877 goto dropwithreset; 1878 } 1879 break; 1880 1881 /* 1882 * If the state is SYN_SENT: 1883 * if seg contains an ACK, but not for our SYN, drop the input. 1884 * if seg contains a RST, then drop the connection. 1885 * if seg does not contain SYN, then drop it. 1886 * Otherwise this is an acceptable SYN segment 1887 * initialize tp->rcv_nxt and tp->irs 1888 * if seg contains ack then advance tp->snd_una 1889 * if seg contains an ECE and ECN support is enabled, the stream 1890 * is ECN capable. 1891 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 1892 * arrange for segment to be acked (eventually) 1893 * continue processing rest of data/controls, beginning with URG 1894 */ 1895 case TCPS_SYN_SENT: 1896 if ((thflags & TH_ACK) && 1897 (SEQ_LEQ(th->th_ack, tp->iss) || 1898 SEQ_GT(th->th_ack, tp->snd_max))) { 1899 rstreason = BANDLIM_UNLIMITED; 1900 goto dropwithreset; 1901 } 1902 if ((thflags & (TH_ACK|TH_RST)) == (TH_ACK|TH_RST)) { 1903 TCP_PROBE5(connect__refused, NULL, tp, 1904 mtod(m, const char *), tp, th); 1905 tp = tcp_drop(tp, ECONNREFUSED); 1906 } 1907 if (thflags & TH_RST) 1908 goto drop; 1909 if (!(thflags & TH_SYN)) 1910 goto drop; 1911 1912 tp->irs = th->th_seq; 1913 tcp_rcvseqinit(tp); 1914 if (thflags & TH_ACK) { 1915 TCPSTAT_INC(tcps_connects); 1916 soisconnected(so); 1917#ifdef MAC 1918 mac_socketpeer_set_from_mbuf(m, so); 1919#endif 1920 /* Do window scaling on this connection? */ 1921 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 1922 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 1923 tp->rcv_scale = tp->request_r_scale; 1924 } 1925 tp->rcv_adv += imin(tp->rcv_wnd, 1926 TCP_MAXWIN << tp->rcv_scale); 1927 tp->snd_una++; /* SYN is acked */ 1928 /* 1929 * If there's data, delay ACK; if there's also a FIN 1930 * ACKNOW will be turned on later. 1931 */ 1932 if (DELAY_ACK(tp, tlen) && tlen != 0) 1933 tcp_timer_activate(tp, TT_DELACK, 1934 tcp_delacktime); 1935 else 1936 tp->t_flags |= TF_ACKNOW; 1937 1938 if ((thflags & TH_ECE) && V_tcp_do_ecn) { 1939 tp->t_flags |= TF_ECN_PERMIT; 1940 TCPSTAT_INC(tcps_ecn_shs); 1941 } 1942 1943 /* 1944 * Received <SYN,ACK> in SYN_SENT[*] state. 1945 * Transitions: 1946 * SYN_SENT --> ESTABLISHED 1947 * SYN_SENT* --> FIN_WAIT_1 1948 */ 1949 tp->t_starttime = ticks; 1950 if (tp->t_flags & TF_NEEDFIN) { 1951 tcp_state_change(tp, TCPS_FIN_WAIT_1); 1952 tp->t_flags &= ~TF_NEEDFIN; 1953 thflags &= ~TH_SYN; 1954 } else { 1955 tcp_state_change(tp, TCPS_ESTABLISHED); 1956 TCP_PROBE5(connect__established, NULL, tp, 1957 mtod(m, const char *), tp, th); 1958 cc_conn_init(tp); 1959 tcp_timer_activate(tp, TT_KEEP, 1960 TP_KEEPIDLE(tp)); 1961 } 1962 } else { 1963 /* 1964 * Received initial SYN in SYN-SENT[*] state => 1965 * simultaneous open. If segment contains CC option 1966 * and there is a cached CC, apply TAO test. 1967 * If it succeeds, connection is * half-synchronized. 1968 * Otherwise, do 3-way handshake: 1969 * SYN-SENT -> SYN-RECEIVED 1970 * SYN-SENT* -> SYN-RECEIVED* 1971 * If there was no CC option, clear cached CC value. 1972 */ 1973 tp->t_flags |= (TF_ACKNOW | TF_NEEDSYN); 1974 tcp_timer_activate(tp, TT_REXMT, 0); 1975 tcp_state_change(tp, TCPS_SYN_RECEIVED); 1976 } 1977 1978 KASSERT(ti_locked == TI_WLOCKED, ("%s: trimthenstep6: " 1979 "ti_locked %d", __func__, ti_locked)); 1980 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 1981 INP_WLOCK_ASSERT(tp->t_inpcb); 1982 1983 /* 1984 * Advance th->th_seq to correspond to first data byte. 1985 * If data, trim to stay within window, 1986 * dropping FIN if necessary. 1987 */ 1988 th->th_seq++; 1989 if (tlen > tp->rcv_wnd) { 1990 todrop = tlen - tp->rcv_wnd; 1991 m_adj(m, -todrop); 1992 tlen = tp->rcv_wnd; 1993 thflags &= ~TH_FIN; 1994 TCPSTAT_INC(tcps_rcvpackafterwin); 1995 TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); 1996 } 1997 tp->snd_wl1 = th->th_seq - 1; 1998 tp->rcv_up = th->th_seq; 1999 /* 2000 * Client side of transaction: already sent SYN and data. 2001 * If the remote host used T/TCP to validate the SYN, 2002 * our data will be ACK'd; if so, enter normal data segment 2003 * processing in the middle of step 5, ack processing. 2004 * Otherwise, goto step 6. 2005 */ 2006 if (thflags & TH_ACK) 2007 goto process_ACK; 2008 2009 goto step6; 2010 2011 /* 2012 * If the state is LAST_ACK or CLOSING or TIME_WAIT: 2013 * do normal processing. 2014 * 2015 * NB: Leftover from RFC1644 T/TCP. Cases to be reused later. 2016 */ 2017 case TCPS_LAST_ACK: 2018 case TCPS_CLOSING: 2019 break; /* continue normal processing */ 2020 } 2021 2022 /* 2023 * States other than LISTEN or SYN_SENT. 2024 * First check the RST flag and sequence number since reset segments 2025 * are exempt from the timestamp and connection count tests. This 2026 * fixes a bug introduced by the Stevens, vol. 2, p. 960 bugfix 2027 * below which allowed reset segments in half the sequence space 2028 * to fall though and be processed (which gives forged reset 2029 * segments with a random sequence number a 50 percent chance of 2030 * killing a connection). 2031 * Then check timestamp, if present. 2032 * Then check the connection count, if present. 2033 * Then check that at least some bytes of segment are within 2034 * receive window. If segment begins before rcv_nxt, 2035 * drop leading data (and SYN); if nothing left, just ack. 2036 * 2037 * 2038 * If the RST bit is set, check the sequence number to see 2039 * if this is a valid reset segment. 2040 * RFC 793 page 37: 2041 * In all states except SYN-SENT, all reset (RST) segments 2042 * are validated by checking their SEQ-fields. A reset is 2043 * valid if its sequence number is in the window. 2044 * Note: this does not take into account delayed ACKs, so 2045 * we should test against last_ack_sent instead of rcv_nxt. 2046 * The sequence number in the reset segment is normally an 2047 * echo of our outgoing acknowlegement numbers, but some hosts 2048 * send a reset with the sequence number at the rightmost edge 2049 * of our receive window, and we have to handle this case. 2050 * Note 2: Paul Watson's paper "Slipping in the Window" has shown 2051 * that brute force RST attacks are possible. To combat this, 2052 * we use a much stricter check while in the ESTABLISHED state, 2053 * only accepting RSTs where the sequence number is equal to 2054 * last_ack_sent. In all other states (the states in which a 2055 * RST is more likely), the more permissive check is used. 2056 * If we have multiple segments in flight, the initial reset 2057 * segment sequence numbers will be to the left of last_ack_sent, 2058 * but they will eventually catch up. 2059 * In any case, it never made sense to trim reset segments to 2060 * fit the receive window since RFC 1122 says: 2061 * 4.2.2.12 RST Segment: RFC-793 Section 3.4 2062 * 2063 * A TCP SHOULD allow a received RST segment to include data. 2064 * 2065 * DISCUSSION 2066 * It has been suggested that a RST segment could contain 2067 * ASCII text that encoded and explained the cause of the 2068 * RST. No standard has yet been established for such 2069 * data. 2070 * 2071 * If the reset segment passes the sequence number test examine 2072 * the state: 2073 * SYN_RECEIVED STATE: 2074 * If passive open, return to LISTEN state. 2075 * If active open, inform user that connection was refused. 2076 * ESTABLISHED, FIN_WAIT_1, FIN_WAIT_2, CLOSE_WAIT STATES: 2077 * Inform user that connection was reset, and close tcb. 2078 * CLOSING, LAST_ACK STATES: 2079 * Close the tcb. 2080 * TIME_WAIT STATE: 2081 * Drop the segment - see Stevens, vol. 2, p. 964 and 2082 * RFC 1337. 2083 */ 2084 if (thflags & TH_RST) { 2085 if (SEQ_GEQ(th->th_seq, tp->last_ack_sent - 1) && 2086 SEQ_LEQ(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) { 2087 switch (tp->t_state) { 2088 2089 case TCPS_SYN_RECEIVED: 2090 so->so_error = ECONNREFUSED; 2091 goto close; 2092 2093 case TCPS_ESTABLISHED: 2094 if (V_tcp_insecure_rst == 0 && 2095 !(SEQ_GEQ(th->th_seq, tp->rcv_nxt - 1) && 2096 SEQ_LEQ(th->th_seq, tp->rcv_nxt + 1)) && 2097 !(SEQ_GEQ(th->th_seq, tp->last_ack_sent - 1) && 2098 SEQ_LEQ(th->th_seq, tp->last_ack_sent + 1))) { 2099 TCPSTAT_INC(tcps_badrst); 2100 goto drop; 2101 } 2102 /* FALLTHROUGH */ 2103 case TCPS_FIN_WAIT_1: 2104 case TCPS_FIN_WAIT_2: 2105 case TCPS_CLOSE_WAIT: 2106 so->so_error = ECONNRESET; 2107 close: 2108 KASSERT(ti_locked == TI_WLOCKED, 2109 ("tcp_do_segment: TH_RST 1 ti_locked %d", 2110 ti_locked)); 2111 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 2112 2113 tcp_state_change(tp, TCPS_CLOSED); 2114 TCPSTAT_INC(tcps_drops); 2115 tp = tcp_close(tp); 2116 break; 2117 2118 case TCPS_CLOSING: 2119 case TCPS_LAST_ACK: 2120 KASSERT(ti_locked == TI_WLOCKED, 2121 ("tcp_do_segment: TH_RST 2 ti_locked %d", 2122 ti_locked)); 2123 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 2124 2125 tp = tcp_close(tp); 2126 break; 2127 } 2128 } 2129 goto drop; 2130 } 2131 2132 /* 2133 * RFC 1323 PAWS: If we have a timestamp reply on this segment 2134 * and it's less than ts_recent, drop it. 2135 */ 2136 if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent && 2137 TSTMP_LT(to.to_tsval, tp->ts_recent)) { 2138 2139 /* Check to see if ts_recent is over 24 days old. */ 2140 if (tcp_ts_getticks() - tp->ts_recent_age > TCP_PAWS_IDLE) { 2141 /* 2142 * Invalidate ts_recent. If this segment updates 2143 * ts_recent, the age will be reset later and ts_recent 2144 * will get a valid value. If it does not, setting 2145 * ts_recent to zero will at least satisfy the 2146 * requirement that zero be placed in the timestamp 2147 * echo reply when ts_recent isn't valid. The 2148 * age isn't reset until we get a valid ts_recent 2149 * because we don't want out-of-order segments to be 2150 * dropped when ts_recent is old. 2151 */ 2152 tp->ts_recent = 0; 2153 } else { 2154 TCPSTAT_INC(tcps_rcvduppack); 2155 TCPSTAT_ADD(tcps_rcvdupbyte, tlen); 2156 TCPSTAT_INC(tcps_pawsdrop); 2157 if (tlen) 2158 goto dropafterack; 2159 goto drop; 2160 } 2161 } 2162 2163 /* 2164 * In the SYN-RECEIVED state, validate that the packet belongs to 2165 * this connection before trimming the data to fit the receive 2166 * window. Check the sequence number versus IRS since we know 2167 * the sequence numbers haven't wrapped. This is a partial fix 2168 * for the "LAND" DoS attack. 2169 */ 2170 if (tp->t_state == TCPS_SYN_RECEIVED && SEQ_LT(th->th_seq, tp->irs)) { 2171 rstreason = BANDLIM_RST_OPENPORT; 2172 goto dropwithreset; 2173 } 2174 2175 todrop = tp->rcv_nxt - th->th_seq; 2176 if (todrop > 0) { 2177 if (thflags & TH_SYN) { 2178 thflags &= ~TH_SYN; 2179 th->th_seq++; 2180 if (th->th_urp > 1) 2181 th->th_urp--; 2182 else 2183 thflags &= ~TH_URG; 2184 todrop--; 2185 } 2186 /* 2187 * Following if statement from Stevens, vol. 2, p. 960. 2188 */ 2189 if (todrop > tlen 2190 || (todrop == tlen && (thflags & TH_FIN) == 0)) { 2191 /* 2192 * Any valid FIN must be to the left of the window. 2193 * At this point the FIN must be a duplicate or out 2194 * of sequence; drop it. 2195 */ 2196 thflags &= ~TH_FIN; 2197 2198 /* 2199 * Send an ACK to resynchronize and drop any data. 2200 * But keep on processing for RST or ACK. 2201 */ 2202 tp->t_flags |= TF_ACKNOW; 2203 todrop = tlen; 2204 TCPSTAT_INC(tcps_rcvduppack); 2205 TCPSTAT_ADD(tcps_rcvdupbyte, todrop); 2206 } else { 2207 TCPSTAT_INC(tcps_rcvpartduppack); 2208 TCPSTAT_ADD(tcps_rcvpartdupbyte, todrop); 2209 } 2210 drop_hdrlen += todrop; /* drop from the top afterwards */ 2211 th->th_seq += todrop; 2212 tlen -= todrop; 2213 if (th->th_urp > todrop) 2214 th->th_urp -= todrop; 2215 else { 2216 thflags &= ~TH_URG; 2217 th->th_urp = 0; 2218 } 2219 } 2220 2221 /* 2222 * If new data are received on a connection after the 2223 * user processes are gone, then RST the other end. 2224 */ 2225 if ((so->so_state & SS_NOFDREF) && 2226 tp->t_state > TCPS_CLOSE_WAIT && tlen) { 2227 KASSERT(ti_locked == TI_WLOCKED, ("%s: SS_NOFDEREF && " 2228 "CLOSE_WAIT && tlen ti_locked %d", __func__, ti_locked)); 2229 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 2230 2231 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 2232 log(LOG_DEBUG, "%s; %s: %s: Received %d bytes of data " 2233 "after socket was closed, " 2234 "sending RST and removing tcpcb\n", 2235 s, __func__, tcpstates[tp->t_state], tlen); 2236 free(s, M_TCPLOG); 2237 } 2238 tp = tcp_close(tp); 2239 TCPSTAT_INC(tcps_rcvafterclose); 2240 rstreason = BANDLIM_UNLIMITED; 2241 goto dropwithreset; 2242 } 2243 2244 /* 2245 * If segment ends after window, drop trailing data 2246 * (and PUSH and FIN); if nothing left, just ACK. 2247 */ 2248 todrop = (th->th_seq + tlen) - (tp->rcv_nxt + tp->rcv_wnd); 2249 if (todrop > 0) { 2250 TCPSTAT_INC(tcps_rcvpackafterwin); 2251 if (todrop >= tlen) { 2252 TCPSTAT_ADD(tcps_rcvbyteafterwin, tlen); 2253 /* 2254 * If window is closed can only take segments at 2255 * window edge, and have to drop data and PUSH from 2256 * incoming segments. Continue processing, but 2257 * remember to ack. Otherwise, drop segment 2258 * and ack. 2259 */ 2260 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 2261 tp->t_flags |= TF_ACKNOW; 2262 TCPSTAT_INC(tcps_rcvwinprobe); 2263 } else 2264 goto dropafterack; 2265 } else 2266 TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); 2267 m_adj(m, -todrop); 2268 tlen -= todrop; 2269 thflags &= ~(TH_PUSH|TH_FIN); 2270 } 2271 2272 /* 2273 * If last ACK falls within this segment's sequence numbers, 2274 * record its timestamp. 2275 * NOTE: 2276 * 1) That the test incorporates suggestions from the latest 2277 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 2278 * 2) That updating only on newer timestamps interferes with 2279 * our earlier PAWS tests, so this check should be solely 2280 * predicated on the sequence space of this segment. 2281 * 3) That we modify the segment boundary check to be 2282 * Last.ACK.Sent <= SEG.SEQ + SEG.Len 2283 * instead of RFC1323's 2284 * Last.ACK.Sent < SEG.SEQ + SEG.Len, 2285 * This modified check allows us to overcome RFC1323's 2286 * limitations as described in Stevens TCP/IP Illustrated 2287 * Vol. 2 p.869. In such cases, we can still calculate the 2288 * RTT correctly when RCV.NXT == Last.ACK.Sent. 2289 */ 2290 if ((to.to_flags & TOF_TS) != 0 && 2291 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 2292 SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen + 2293 ((thflags & (TH_SYN|TH_FIN)) != 0))) { 2294 tp->ts_recent_age = tcp_ts_getticks(); 2295 tp->ts_recent = to.to_tsval; 2296 } 2297 2298 /* 2299 * If a SYN is in the window, then this is an 2300 * error and we send an RST and drop the connection. 2301 */ 2302 if (thflags & TH_SYN) { 2303 KASSERT(ti_locked == TI_WLOCKED, 2304 ("tcp_do_segment: TH_SYN ti_locked %d", ti_locked)); 2305 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 2306 2307 tp = tcp_drop(tp, ECONNRESET); 2308 rstreason = BANDLIM_UNLIMITED; 2309 goto drop; 2310 } 2311 2312 /* 2313 * If the ACK bit is off: if in SYN-RECEIVED state or SENDSYN 2314 * flag is on (half-synchronized state), then queue data for 2315 * later processing; else drop segment and return. 2316 */ 2317 if ((thflags & TH_ACK) == 0) { 2318 if (tp->t_state == TCPS_SYN_RECEIVED || 2319 (tp->t_flags & TF_NEEDSYN)) 2320 goto step6; 2321 else if (tp->t_flags & TF_ACKNOW) 2322 goto dropafterack; 2323 else 2324 goto drop; 2325 } 2326 2327 /* 2328 * Ack processing. 2329 */ 2330 switch (tp->t_state) { 2331 2332 /* 2333 * In SYN_RECEIVED state, the ack ACKs our SYN, so enter 2334 * ESTABLISHED state and continue processing. 2335 * The ACK was checked above. 2336 */ 2337 case TCPS_SYN_RECEIVED: 2338 2339 TCPSTAT_INC(tcps_connects); 2340 soisconnected(so); 2341 /* Do window scaling? */ 2342 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2343 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2344 tp->rcv_scale = tp->request_r_scale; 2345 tp->snd_wnd = tiwin; 2346 } 2347 /* 2348 * Make transitions: 2349 * SYN-RECEIVED -> ESTABLISHED 2350 * SYN-RECEIVED* -> FIN-WAIT-1 2351 */ 2352 tp->t_starttime = ticks; 2353 if (tp->t_flags & TF_NEEDFIN) { 2354 tcp_state_change(tp, TCPS_FIN_WAIT_1); 2355 tp->t_flags &= ~TF_NEEDFIN; 2356 } else { 2357 tcp_state_change(tp, TCPS_ESTABLISHED); 2358 TCP_PROBE5(accept__established, NULL, tp, 2359 mtod(m, const char *), tp, th); 2360 cc_conn_init(tp); 2361 tcp_timer_activate(tp, TT_KEEP, TP_KEEPIDLE(tp)); 2362 } 2363 /* 2364 * If segment contains data or ACK, will call tcp_reass() 2365 * later; if not, do so now to pass queued data to user. 2366 */ 2367 if (tlen == 0 && (thflags & TH_FIN) == 0) 2368 (void) tcp_reass(tp, (struct tcphdr *)0, 0, 2369 (struct mbuf *)0); 2370 tp->snd_wl1 = th->th_seq - 1; 2371 /* FALLTHROUGH */ 2372 2373 /* 2374 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 2375 * ACKs. If the ack is in the range 2376 * tp->snd_una < th->th_ack <= tp->snd_max 2377 * then advance tp->snd_una to th->th_ack and drop 2378 * data from the retransmission queue. If this ACK reflects 2379 * more up to date window information we update our window information. 2380 */ 2381 case TCPS_ESTABLISHED: 2382 case TCPS_FIN_WAIT_1: 2383 case TCPS_FIN_WAIT_2: 2384 case TCPS_CLOSE_WAIT: 2385 case TCPS_CLOSING: 2386 case TCPS_LAST_ACK: 2387 if (SEQ_GT(th->th_ack, tp->snd_max)) { 2388 TCPSTAT_INC(tcps_rcvacktoomuch); 2389 goto dropafterack; 2390 } 2391 if ((tp->t_flags & TF_SACK_PERMIT) && 2392 ((to.to_flags & TOF_SACK) || 2393 !TAILQ_EMPTY(&tp->snd_holes))) 2394 tcp_sack_doack(tp, &to, th->th_ack); 2395 2396 /* Run HHOOK_TCP_ESTABLISHED_IN helper hooks. */ 2397 hhook_run_tcp_est_in(tp, th, &to); 2398 2399 if (SEQ_LEQ(th->th_ack, tp->snd_una)) { 2400 if (tlen == 0 && tiwin == tp->snd_wnd) { 2401 TCPSTAT_INC(tcps_rcvdupack); 2402 /* 2403 * If we have outstanding data (other than 2404 * a window probe), this is a completely 2405 * duplicate ack (ie, window info didn't 2406 * change), the ack is the biggest we've 2407 * seen and we've seen exactly our rexmt 2408 * threshhold of them, assume a packet 2409 * has been dropped and retransmit it. 2410 * Kludge snd_nxt & the congestion 2411 * window so we send only this one 2412 * packet. 2413 * 2414 * We know we're losing at the current 2415 * window size so do congestion avoidance 2416 * (set ssthresh to half the current window 2417 * and pull our congestion window back to 2418 * the new ssthresh). 2419 * 2420 * Dup acks mean that packets have left the 2421 * network (they're now cached at the receiver) 2422 * so bump cwnd by the amount in the receiver 2423 * to keep a constant cwnd packets in the 2424 * network. 2425 * 2426 * When using TCP ECN, notify the peer that 2427 * we reduced the cwnd. 2428 */ 2429 if (!tcp_timer_active(tp, TT_REXMT) || 2430 th->th_ack != tp->snd_una) 2431 tp->t_dupacks = 0; 2432 else if (++tp->t_dupacks > tcprexmtthresh || 2433 IN_FASTRECOVERY(tp->t_flags)) { 2434 cc_ack_received(tp, th, CC_DUPACK); 2435 if ((tp->t_flags & TF_SACK_PERMIT) && 2436 IN_FASTRECOVERY(tp->t_flags)) { 2437 int awnd; 2438 2439 /* 2440 * Compute the amount of data in flight first. 2441 * We can inject new data into the pipe iff 2442 * we have less than 1/2 the original window's 2443 * worth of data in flight. 2444 */ 2445 awnd = (tp->snd_nxt - tp->snd_fack) + 2446 tp->sackhint.sack_bytes_rexmit; 2447 if (awnd < tp->snd_ssthresh) { 2448 tp->snd_cwnd += tp->t_maxseg; 2449 if (tp->snd_cwnd > tp->snd_ssthresh) 2450 tp->snd_cwnd = tp->snd_ssthresh; 2451 } 2452 } else 2453 tp->snd_cwnd += tp->t_maxseg; 2454 if ((thflags & TH_FIN) && 2455 (TCPS_HAVERCVDFIN(tp->t_state) == 0)) { 2456 /* 2457 * If its a fin we need to process 2458 * it to avoid a race where both 2459 * sides enter FIN-WAIT and send FIN|ACK 2460 * at the same time. 2461 */ 2462 break; 2463 } 2464 (void) tcp_output(tp); 2465 goto drop; 2466 } else if (tp->t_dupacks == tcprexmtthresh) { 2467 tcp_seq onxt = tp->snd_nxt; 2468 2469 /* 2470 * If we're doing sack, check to 2471 * see if we're already in sack 2472 * recovery. If we're not doing sack, 2473 * check to see if we're in newreno 2474 * recovery. 2475 */ 2476 if (tp->t_flags & TF_SACK_PERMIT) { 2477 if (IN_FASTRECOVERY(tp->t_flags)) { 2478 tp->t_dupacks = 0; 2479 break; 2480 } 2481 } else { 2482 if (SEQ_LEQ(th->th_ack, 2483 tp->snd_recover)) { 2484 tp->t_dupacks = 0; 2485 break; 2486 } 2487 } 2488 /* Congestion signal before ack. */ 2489 cc_cong_signal(tp, th, CC_NDUPACK); 2490 cc_ack_received(tp, th, CC_DUPACK); 2491 tcp_timer_activate(tp, TT_REXMT, 0); 2492 tp->t_rtttime = 0; 2493 if (tp->t_flags & TF_SACK_PERMIT) { 2494 TCPSTAT_INC( 2495 tcps_sack_recovery_episode); 2496 tp->sack_newdata = tp->snd_nxt; 2497 tp->snd_cwnd = tp->t_maxseg; 2498 (void) tcp_output(tp); 2499 goto drop; 2500 } 2501 tp->snd_nxt = th->th_ack; 2502 tp->snd_cwnd = tp->t_maxseg; 2503 if ((thflags & TH_FIN) && 2504 (TCPS_HAVERCVDFIN(tp->t_state) == 0)) { 2505 /* 2506 * If its a fin we need to process 2507 * it to avoid a race where both 2508 * sides enter FIN-WAIT and send FIN|ACK 2509 * at the same time. 2510 */ 2511 break; 2512 } 2513 (void) tcp_output(tp); 2514 KASSERT(tp->snd_limited <= 2, 2515 ("%s: tp->snd_limited too big", 2516 __func__)); 2517 tp->snd_cwnd = tp->snd_ssthresh + 2518 tp->t_maxseg * 2519 (tp->t_dupacks - tp->snd_limited); 2520 if (SEQ_GT(onxt, tp->snd_nxt)) 2521 tp->snd_nxt = onxt; 2522 goto drop; 2523 } else if (V_tcp_do_rfc3042) { 2524 cc_ack_received(tp, th, CC_DUPACK); 2525 u_long oldcwnd = tp->snd_cwnd; 2526 tcp_seq oldsndmax = tp->snd_max; 2527 u_int sent; 2528 int avail; 2529 2530 KASSERT(tp->t_dupacks == 1 || 2531 tp->t_dupacks == 2, 2532 ("%s: dupacks not 1 or 2", 2533 __func__)); 2534 if (tp->t_dupacks == 1) 2535 tp->snd_limited = 0; 2536 tp->snd_cwnd = 2537 (tp->snd_nxt - tp->snd_una) + 2538 (tp->t_dupacks - tp->snd_limited) * 2539 tp->t_maxseg; 2540 if ((thflags & TH_FIN) && 2541 (TCPS_HAVERCVDFIN(tp->t_state) == 0)) { 2542 /* 2543 * If its a fin we need to process 2544 * it to avoid a race where both 2545 * sides enter FIN-WAIT and send FIN|ACK 2546 * at the same time. 2547 */ 2548 break; 2549 } 2550 /* 2551 * Only call tcp_output when there 2552 * is new data available to be sent. 2553 * Otherwise we would send pure ACKs. 2554 */ 2555 SOCKBUF_LOCK(&so->so_snd); 2556 avail = so->so_snd.sb_cc - 2557 (tp->snd_nxt - tp->snd_una); 2558 SOCKBUF_UNLOCK(&so->so_snd); 2559 if (avail > 0) 2560 (void) tcp_output(tp); 2561 sent = tp->snd_max - oldsndmax; 2562 if (sent > tp->t_maxseg) { 2563 KASSERT((tp->t_dupacks == 2 && 2564 tp->snd_limited == 0) || 2565 (sent == tp->t_maxseg + 1 && 2566 tp->t_flags & TF_SENTFIN), 2567 ("%s: sent too much", 2568 __func__)); 2569 tp->snd_limited = 2; 2570 } else if (sent > 0) 2571 ++tp->snd_limited; 2572 tp->snd_cwnd = oldcwnd; 2573 goto drop; 2574 } 2575 } else 2576 tp->t_dupacks = 0; 2577 break; 2578 } 2579 2580 KASSERT(SEQ_GT(th->th_ack, tp->snd_una), 2581 ("%s: th_ack <= snd_una", __func__)); 2582 2583 /* 2584 * If the congestion window was inflated to account 2585 * for the other side's cached packets, retract it. 2586 */ 2587 if (IN_FASTRECOVERY(tp->t_flags)) { 2588 if (SEQ_LT(th->th_ack, tp->snd_recover)) { 2589 if (tp->t_flags & TF_SACK_PERMIT) 2590 tcp_sack_partialack(tp, th); 2591 else 2592 tcp_newreno_partial_ack(tp, th); 2593 } else 2594 cc_post_recovery(tp, th); 2595 } 2596 tp->t_dupacks = 0; 2597 /* 2598 * If we reach this point, ACK is not a duplicate, 2599 * i.e., it ACKs something we sent. 2600 */ 2601 if (tp->t_flags & TF_NEEDSYN) { 2602 /* 2603 * T/TCP: Connection was half-synchronized, and our 2604 * SYN has been ACK'd (so connection is now fully 2605 * synchronized). Go to non-starred state, 2606 * increment snd_una for ACK of SYN, and check if 2607 * we can do window scaling. 2608 */ 2609 tp->t_flags &= ~TF_NEEDSYN; 2610 tp->snd_una++; 2611 /* Do window scaling? */ 2612 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2613 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2614 tp->rcv_scale = tp->request_r_scale; 2615 /* Send window already scaled. */ 2616 } 2617 } 2618 2619process_ACK: 2620 INP_WLOCK_ASSERT(tp->t_inpcb); 2621 2622 acked = BYTES_THIS_ACK(tp, th); 2623 TCPSTAT_INC(tcps_rcvackpack); 2624 TCPSTAT_ADD(tcps_rcvackbyte, acked); 2625 2626 /* 2627 * If we just performed our first retransmit, and the ACK 2628 * arrives within our recovery window, then it was a mistake 2629 * to do the retransmit in the first place. Recover our 2630 * original cwnd and ssthresh, and proceed to transmit where 2631 * we left off. 2632 */ 2633 if (tp->t_rxtshift == 1 && tp->t_flags & TF_PREVVALID && 2634 (int)(ticks - tp->t_badrxtwin) < 0) 2635 cc_cong_signal(tp, th, CC_RTO_ERR); 2636 2637 /* 2638 * If we have a timestamp reply, update smoothed 2639 * round trip time. If no timestamp is present but 2640 * transmit timer is running and timed sequence 2641 * number was acked, update smoothed round trip time. 2642 * Since we now have an rtt measurement, cancel the 2643 * timer backoff (cf., Phil Karn's retransmit alg.). 2644 * Recompute the initial retransmit timer. 2645 * 2646 * Some boxes send broken timestamp replies 2647 * during the SYN+ACK phase, ignore 2648 * timestamps of 0 or we could calculate a 2649 * huge RTT and blow up the retransmit timer. 2650 */ 2651 if ((to.to_flags & TOF_TS) != 0 && to.to_tsecr) { 2652 u_int t; 2653 2654 t = tcp_ts_getticks() - to.to_tsecr; 2655 if (!tp->t_rttlow || tp->t_rttlow > t) 2656 tp->t_rttlow = t; 2657 tcp_xmit_timer(tp, TCP_TS_TO_TICKS(t) + 1); 2658 } else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) { 2659 if (!tp->t_rttlow || tp->t_rttlow > ticks - tp->t_rtttime) 2660 tp->t_rttlow = ticks - tp->t_rtttime; 2661 tcp_xmit_timer(tp, ticks - tp->t_rtttime); 2662 } 2663 2664 /* 2665 * If all outstanding data is acked, stop retransmit 2666 * timer and remember to restart (more output or persist). 2667 * If there is more data to be acked, restart retransmit 2668 * timer, using current (possibly backed-off) value. 2669 */ 2670 if (th->th_ack == tp->snd_max) { 2671 tcp_timer_activate(tp, TT_REXMT, 0); 2672 needoutput = 1; 2673 } else if (!tcp_timer_active(tp, TT_PERSIST)) 2674 tcp_timer_activate(tp, TT_REXMT, tp->t_rxtcur); 2675 2676 /* 2677 * If no data (only SYN) was ACK'd, 2678 * skip rest of ACK processing. 2679 */ 2680 if (acked == 0) 2681 goto step6; 2682 2683 /* 2684 * Let the congestion control algorithm update congestion 2685 * control related information. This typically means increasing 2686 * the congestion window. 2687 */ 2688 cc_ack_received(tp, th, CC_ACK); 2689 2690 SOCKBUF_LOCK(&so->so_snd); 2691 if (acked > so->so_snd.sb_cc) { 2692 tp->snd_wnd -= so->so_snd.sb_cc; 2693 mfree = sbcut_locked(&so->so_snd, 2694 (int)so->so_snd.sb_cc); 2695 ourfinisacked = 1; 2696 } else { 2697 mfree = sbcut_locked(&so->so_snd, acked); 2698 tp->snd_wnd -= acked; 2699 ourfinisacked = 0; 2700 } 2701 /* NB: sowwakeup_locked() does an implicit unlock. */ 2702 sowwakeup_locked(so); 2703 m_freem(mfree); 2704 /* Detect una wraparound. */ 2705 if (!IN_RECOVERY(tp->t_flags) && 2706 SEQ_GT(tp->snd_una, tp->snd_recover) && 2707 SEQ_LEQ(th->th_ack, tp->snd_recover)) 2708 tp->snd_recover = th->th_ack - 1; 2709 /* XXXLAS: Can this be moved up into cc_post_recovery? */ 2710 if (IN_RECOVERY(tp->t_flags) && 2711 SEQ_GEQ(th->th_ack, tp->snd_recover)) { 2712 EXIT_RECOVERY(tp->t_flags); 2713 } 2714 tp->snd_una = th->th_ack; 2715 if (tp->t_flags & TF_SACK_PERMIT) { 2716 if (SEQ_GT(tp->snd_una, tp->snd_recover)) 2717 tp->snd_recover = tp->snd_una; 2718 } 2719 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2720 tp->snd_nxt = tp->snd_una; 2721 2722 switch (tp->t_state) { 2723 2724 /* 2725 * In FIN_WAIT_1 STATE in addition to the processing 2726 * for the ESTABLISHED state if our FIN is now acknowledged 2727 * then enter FIN_WAIT_2. 2728 */ 2729 case TCPS_FIN_WAIT_1: 2730 if (ourfinisacked) { 2731 /* 2732 * If we can't receive any more 2733 * data, then closing user can proceed. 2734 * Starting the timer is contrary to the 2735 * specification, but if we don't get a FIN 2736 * we'll hang forever. 2737 * 2738 * XXXjl: 2739 * we should release the tp also, and use a 2740 * compressed state. 2741 */ 2742 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 2743 soisdisconnected(so); 2744 tcp_timer_activate(tp, TT_2MSL, 2745 (tcp_fast_finwait2_recycle ? 2746 tcp_finwait2_timeout : 2747 TP_MAXIDLE(tp))); 2748 } 2749 tcp_state_change(tp, TCPS_FIN_WAIT_2); 2750 } 2751 break; 2752 2753 /* 2754 * In CLOSING STATE in addition to the processing for 2755 * the ESTABLISHED state if the ACK acknowledges our FIN 2756 * then enter the TIME-WAIT state, otherwise ignore 2757 * the segment. 2758 */ 2759 case TCPS_CLOSING: 2760 if (ourfinisacked) { 2761 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 2762 tcp_twstart(tp); 2763 INP_INFO_WUNLOCK(&V_tcbinfo); 2764 m_freem(m); 2765 return; 2766 } 2767 break; 2768 2769 /* 2770 * In LAST_ACK, we may still be waiting for data to drain 2771 * and/or to be acked, as well as for the ack of our FIN. 2772 * If our FIN is now acknowledged, delete the TCB, 2773 * enter the closed state and return. 2774 */ 2775 case TCPS_LAST_ACK: 2776 if (ourfinisacked) { 2777 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 2778 tp = tcp_close(tp); 2779 goto drop; 2780 } 2781 break; 2782 } 2783 } 2784 2785step6: 2786 INP_WLOCK_ASSERT(tp->t_inpcb); 2787 2788 /* 2789 * Update window information. 2790 * Don't look at window if no ACK: TAC's send garbage on first SYN. 2791 */ 2792 if ((thflags & TH_ACK) && 2793 (SEQ_LT(tp->snd_wl1, th->th_seq) || 2794 (tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) || 2795 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) { 2796 /* keep track of pure window updates */ 2797 if (tlen == 0 && 2798 tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) 2799 TCPSTAT_INC(tcps_rcvwinupd); 2800 tp->snd_wnd = tiwin; 2801 tp->snd_wl1 = th->th_seq; 2802 tp->snd_wl2 = th->th_ack; 2803 if (tp->snd_wnd > tp->max_sndwnd) 2804 tp->max_sndwnd = tp->snd_wnd; 2805 needoutput = 1; 2806 } 2807 2808 /* 2809 * Process segments with URG. 2810 */ 2811 if ((thflags & TH_URG) && th->th_urp && 2812 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2813 /* 2814 * This is a kludge, but if we receive and accept 2815 * random urgent pointers, we'll crash in 2816 * soreceive. It's hard to imagine someone 2817 * actually wanting to send this much urgent data. 2818 */ 2819 SOCKBUF_LOCK(&so->so_rcv); 2820 if (th->th_urp + so->so_rcv.sb_cc > sb_max) { 2821 th->th_urp = 0; /* XXX */ 2822 thflags &= ~TH_URG; /* XXX */ 2823 SOCKBUF_UNLOCK(&so->so_rcv); /* XXX */ 2824 goto dodata; /* XXX */ 2825 } 2826 /* 2827 * If this segment advances the known urgent pointer, 2828 * then mark the data stream. This should not happen 2829 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 2830 * a FIN has been received from the remote side. 2831 * In these states we ignore the URG. 2832 * 2833 * According to RFC961 (Assigned Protocols), 2834 * the urgent pointer points to the last octet 2835 * of urgent data. We continue, however, 2836 * to consider it to indicate the first octet 2837 * of data past the urgent section as the original 2838 * spec states (in one of two places). 2839 */ 2840 if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) { 2841 tp->rcv_up = th->th_seq + th->th_urp; 2842 so->so_oobmark = so->so_rcv.sb_cc + 2843 (tp->rcv_up - tp->rcv_nxt) - 1; 2844 if (so->so_oobmark == 0) 2845 so->so_rcv.sb_state |= SBS_RCVATMARK; 2846 sohasoutofband(so); 2847 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); 2848 } 2849 SOCKBUF_UNLOCK(&so->so_rcv); 2850 /* 2851 * Remove out of band data so doesn't get presented to user. 2852 * This can happen independent of advancing the URG pointer, 2853 * but if two URG's are pending at once, some out-of-band 2854 * data may creep in... ick. 2855 */ 2856 if (th->th_urp <= (u_long)tlen && 2857 !(so->so_options & SO_OOBINLINE)) { 2858 /* hdr drop is delayed */ 2859 tcp_pulloutofband(so, th, m, drop_hdrlen); 2860 } 2861 } else { 2862 /* 2863 * If no out of band data is expected, 2864 * pull receive urgent pointer along 2865 * with the receive window. 2866 */ 2867 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) 2868 tp->rcv_up = tp->rcv_nxt; 2869 } 2870dodata: /* XXX */ 2871 INP_WLOCK_ASSERT(tp->t_inpcb); 2872 2873 /* 2874 * Process the segment text, merging it into the TCP sequencing queue, 2875 * and arranging for acknowledgment of receipt if necessary. 2876 * This process logically involves adjusting tp->rcv_wnd as data 2877 * is presented to the user (this happens in tcp_usrreq.c, 2878 * case PRU_RCVD). If a FIN has already been received on this 2879 * connection then we just ignore the text. 2880 */ 2881 if ((tlen || (thflags & TH_FIN)) && 2882 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2883 tcp_seq save_start = th->th_seq; 2884 m_adj(m, drop_hdrlen); /* delayed header drop */ 2885 /* 2886 * Insert segment which includes th into TCP reassembly queue 2887 * with control block tp. Set thflags to whether reassembly now 2888 * includes a segment with FIN. This handles the common case 2889 * inline (segment is the next to be received on an established 2890 * connection, and the queue is empty), avoiding linkage into 2891 * and removal from the queue and repetition of various 2892 * conversions. 2893 * Set DELACK for segments received in order, but ack 2894 * immediately when segments are out of order (so 2895 * fast retransmit can work). 2896 */ 2897 if (th->th_seq == tp->rcv_nxt && 2898 LIST_EMPTY(&tp->t_segq) && 2899 TCPS_HAVEESTABLISHED(tp->t_state)) { 2900 if (DELAY_ACK(tp, tlen)) 2901 tp->t_flags |= TF_DELACK; 2902 else 2903 tp->t_flags |= TF_ACKNOW; 2904 tp->rcv_nxt += tlen; 2905 thflags = th->th_flags & TH_FIN; 2906 TCPSTAT_INC(tcps_rcvpack); 2907 TCPSTAT_ADD(tcps_rcvbyte, tlen); 2908 ND6_HINT(tp); 2909 SOCKBUF_LOCK(&so->so_rcv); 2910 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) 2911 m_freem(m); 2912 else 2913 sbappendstream_locked(&so->so_rcv, m); 2914 /* NB: sorwakeup_locked() does an implicit unlock. */ 2915 sorwakeup_locked(so); 2916 } else { 2917 /* 2918 * XXX: Due to the header drop above "th" is 2919 * theoretically invalid by now. Fortunately 2920 * m_adj() doesn't actually frees any mbufs 2921 * when trimming from the head. 2922 */ 2923 thflags = tcp_reass(tp, th, &tlen, m); 2924 tp->t_flags |= TF_ACKNOW; 2925 } 2926 if (tlen > 0 && (tp->t_flags & TF_SACK_PERMIT)) 2927 tcp_update_sack_list(tp, save_start, save_start + tlen); 2928#if 0 2929 /* 2930 * Note the amount of data that peer has sent into 2931 * our window, in order to estimate the sender's 2932 * buffer size. 2933 * XXX: Unused. 2934 */ 2935 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt)) 2936 len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); 2937 else 2938 len = so->so_rcv.sb_hiwat; 2939#endif 2940 } else { 2941 m_freem(m); 2942 thflags &= ~TH_FIN; 2943 } 2944 2945 /* 2946 * If FIN is received ACK the FIN and let the user know 2947 * that the connection is closing. 2948 */ 2949 if (thflags & TH_FIN) { 2950 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2951 socantrcvmore(so); 2952 /* 2953 * If connection is half-synchronized 2954 * (ie NEEDSYN flag on) then delay ACK, 2955 * so it may be piggybacked when SYN is sent. 2956 * Otherwise, since we received a FIN then no 2957 * more input can be expected, send ACK now. 2958 */ 2959 if (tp->t_flags & TF_NEEDSYN) 2960 tp->t_flags |= TF_DELACK; 2961 else 2962 tp->t_flags |= TF_ACKNOW; 2963 tp->rcv_nxt++; 2964 } 2965 switch (tp->t_state) { 2966 2967 /* 2968 * In SYN_RECEIVED and ESTABLISHED STATES 2969 * enter the CLOSE_WAIT state. 2970 */ 2971 case TCPS_SYN_RECEIVED: 2972 tp->t_starttime = ticks; 2973 /* FALLTHROUGH */ 2974 case TCPS_ESTABLISHED: 2975 tcp_state_change(tp, TCPS_CLOSE_WAIT); 2976 break; 2977 2978 /* 2979 * If still in FIN_WAIT_1 STATE FIN has not been acked so 2980 * enter the CLOSING state. 2981 */ 2982 case TCPS_FIN_WAIT_1: 2983 tcp_state_change(tp, TCPS_CLOSING); 2984 break; 2985 2986 /* 2987 * In FIN_WAIT_2 state enter the TIME_WAIT state, 2988 * starting the time-wait timer, turning off the other 2989 * standard timers. 2990 */ 2991 case TCPS_FIN_WAIT_2: 2992 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 2993 KASSERT(ti_locked == TI_WLOCKED, ("%s: dodata " 2994 "TCP_FIN_WAIT_2 ti_locked: %d", __func__, 2995 ti_locked)); 2996 2997 tcp_twstart(tp); 2998 INP_INFO_WUNLOCK(&V_tcbinfo); 2999 return; 3000 } 3001 } 3002 if (ti_locked == TI_WLOCKED) 3003 INP_INFO_WUNLOCK(&V_tcbinfo); 3004 ti_locked = TI_UNLOCKED; 3005 3006#ifdef TCPDEBUG 3007 if (so->so_options & SO_DEBUG) 3008 tcp_trace(TA_INPUT, ostate, tp, (void *)tcp_saveipgen, 3009 &tcp_savetcp, 0); 3010#endif 3011 3012 /* 3013 * Return any desired output. 3014 */ 3015 if (needoutput || (tp->t_flags & TF_ACKNOW)) 3016 (void) tcp_output(tp); 3017 3018check_delack: 3019 KASSERT(ti_locked == TI_UNLOCKED, ("%s: check_delack ti_locked %d", 3020 __func__, ti_locked)); 3021 INP_INFO_UNLOCK_ASSERT(&V_tcbinfo); 3022 INP_WLOCK_ASSERT(tp->t_inpcb); 3023 3024 if (tp->t_flags & TF_DELACK) { 3025 tp->t_flags &= ~TF_DELACK; 3026 tcp_timer_activate(tp, TT_DELACK, tcp_delacktime); 3027 } 3028 INP_WUNLOCK(tp->t_inpcb); 3029 return; 3030 3031dropafterack: 3032 /* 3033 * Generate an ACK dropping incoming segment if it occupies 3034 * sequence space, where the ACK reflects our state. 3035 * 3036 * We can now skip the test for the RST flag since all 3037 * paths to this code happen after packets containing 3038 * RST have been dropped. 3039 * 3040 * In the SYN-RECEIVED state, don't send an ACK unless the 3041 * segment we received passes the SYN-RECEIVED ACK test. 3042 * If it fails send a RST. This breaks the loop in the 3043 * "LAND" DoS attack, and also prevents an ACK storm 3044 * between two listening ports that have been sent forged 3045 * SYN segments, each with the source address of the other. 3046 */ 3047 if (tp->t_state == TCPS_SYN_RECEIVED && (thflags & TH_ACK) && 3048 (SEQ_GT(tp->snd_una, th->th_ack) || 3049 SEQ_GT(th->th_ack, tp->snd_max)) ) { 3050 rstreason = BANDLIM_RST_OPENPORT; 3051 goto dropwithreset; 3052 } 3053#ifdef TCPDEBUG 3054 if (so->so_options & SO_DEBUG) 3055 tcp_trace(TA_DROP, ostate, tp, (void *)tcp_saveipgen, 3056 &tcp_savetcp, 0); 3057#endif 3058 if (ti_locked == TI_WLOCKED) 3059 INP_INFO_WUNLOCK(&V_tcbinfo); 3060 ti_locked = TI_UNLOCKED; 3061 3062 tp->t_flags |= TF_ACKNOW; 3063 (void) tcp_output(tp); 3064 INP_WUNLOCK(tp->t_inpcb); 3065 m_freem(m); 3066 return; 3067 3068dropwithreset: 3069 if (ti_locked == TI_WLOCKED) 3070 INP_INFO_WUNLOCK(&V_tcbinfo); 3071 ti_locked = TI_UNLOCKED; 3072 3073 if (tp != NULL) { 3074 tcp_dropwithreset(m, th, tp, tlen, rstreason); 3075 INP_WUNLOCK(tp->t_inpcb); 3076 } else 3077 tcp_dropwithreset(m, th, NULL, tlen, rstreason); 3078 return; 3079 3080drop: 3081 if (ti_locked == TI_WLOCKED) { 3082 INP_INFO_WUNLOCK(&V_tcbinfo); 3083 ti_locked = TI_UNLOCKED; 3084 } 3085#ifdef INVARIANTS 3086 else 3087 INP_INFO_UNLOCK_ASSERT(&V_tcbinfo); 3088#endif 3089 3090 /* 3091 * Drop space held by incoming segment and return. 3092 */ 3093#ifdef TCPDEBUG 3094 if (tp == NULL || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 3095 tcp_trace(TA_DROP, ostate, tp, (void *)tcp_saveipgen, 3096 &tcp_savetcp, 0); 3097#endif 3098 if (tp != NULL) 3099 INP_WUNLOCK(tp->t_inpcb); 3100 m_freem(m); 3101} 3102 3103/* 3104 * Issue RST and make ACK acceptable to originator of segment. 3105 * The mbuf must still include the original packet header. 3106 * tp may be NULL. 3107 */ 3108static void 3109tcp_dropwithreset(struct mbuf *m, struct tcphdr *th, struct tcpcb *tp, 3110 int tlen, int rstreason) 3111{ 3112#ifdef INET 3113 struct ip *ip; 3114#endif 3115#ifdef INET6 3116 struct ip6_hdr *ip6; 3117#endif 3118 3119 if (tp != NULL) { 3120 INP_WLOCK_ASSERT(tp->t_inpcb); 3121 } 3122 3123 /* Don't bother if destination was broadcast/multicast. */ 3124 if ((th->th_flags & TH_RST) || m->m_flags & (M_BCAST|M_MCAST)) 3125 goto drop; 3126#ifdef INET6 3127 if (mtod(m, struct ip *)->ip_v == 6) { 3128 ip6 = mtod(m, struct ip6_hdr *); 3129 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 3130 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) 3131 goto drop; 3132 /* IPv6 anycast check is done at tcp6_input() */ 3133 } 3134#endif 3135#if defined(INET) && defined(INET6) 3136 else 3137#endif 3138#ifdef INET 3139 { 3140 ip = mtod(m, struct ip *); 3141 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 3142 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 3143 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || 3144 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 3145 goto drop; 3146 } 3147#endif 3148 3149 /* Perform bandwidth limiting. */ 3150 if (badport_bandlim(rstreason) < 0) 3151 goto drop; 3152 3153 /* tcp_respond consumes the mbuf chain. */ 3154 if (th->th_flags & TH_ACK) { 3155 tcp_respond(tp, mtod(m, void *), th, m, (tcp_seq)0, 3156 th->th_ack, TH_RST); 3157 } else { 3158 if (th->th_flags & TH_SYN) 3159 tlen++; 3160 tcp_respond(tp, mtod(m, void *), th, m, th->th_seq+tlen, 3161 (tcp_seq)0, TH_RST|TH_ACK); 3162 } 3163 return; 3164drop: 3165 m_freem(m); 3166} 3167 3168/* 3169 * Parse TCP options and place in tcpopt. 3170 */ 3171static void 3172tcp_dooptions(struct tcpopt *to, u_char *cp, int cnt, int flags) 3173{ 3174 int opt, optlen; 3175 3176 to->to_flags = 0; 3177 for (; cnt > 0; cnt -= optlen, cp += optlen) { 3178 opt = cp[0]; 3179 if (opt == TCPOPT_EOL) 3180 break; 3181 if (opt == TCPOPT_NOP) 3182 optlen = 1; 3183 else { 3184 if (cnt < 2) 3185 break; 3186 optlen = cp[1]; 3187 if (optlen < 2 || optlen > cnt) 3188 break; 3189 } 3190 switch (opt) { 3191 case TCPOPT_MAXSEG: 3192 if (optlen != TCPOLEN_MAXSEG) 3193 continue; 3194 if (!(flags & TO_SYN)) 3195 continue; 3196 to->to_flags |= TOF_MSS; 3197 bcopy((char *)cp + 2, 3198 (char *)&to->to_mss, sizeof(to->to_mss)); 3199 to->to_mss = ntohs(to->to_mss); 3200 break; 3201 case TCPOPT_WINDOW: 3202 if (optlen != TCPOLEN_WINDOW) 3203 continue; 3204 if (!(flags & TO_SYN)) 3205 continue; 3206 to->to_flags |= TOF_SCALE; 3207 to->to_wscale = min(cp[2], TCP_MAX_WINSHIFT); 3208 break; 3209 case TCPOPT_TIMESTAMP: 3210 if (optlen != TCPOLEN_TIMESTAMP) 3211 continue; 3212 to->to_flags |= TOF_TS; 3213 bcopy((char *)cp + 2, 3214 (char *)&to->to_tsval, sizeof(to->to_tsval)); 3215 to->to_tsval = ntohl(to->to_tsval); 3216 bcopy((char *)cp + 6, 3217 (char *)&to->to_tsecr, sizeof(to->to_tsecr)); 3218 to->to_tsecr = ntohl(to->to_tsecr); 3219 break; 3220#ifdef TCP_SIGNATURE 3221 /* 3222 * XXX In order to reply to a host which has set the 3223 * TCP_SIGNATURE option in its initial SYN, we have to 3224 * record the fact that the option was observed here 3225 * for the syncache code to perform the correct response. 3226 */ 3227 case TCPOPT_SIGNATURE: 3228 if (optlen != TCPOLEN_SIGNATURE) 3229 continue; 3230 to->to_flags |= TOF_SIGNATURE; 3231 to->to_signature = cp + 2; 3232 break; 3233#endif 3234 case TCPOPT_SACK_PERMITTED: 3235 if (optlen != TCPOLEN_SACK_PERMITTED) 3236 continue; 3237 if (!(flags & TO_SYN)) 3238 continue; 3239 if (!V_tcp_do_sack) 3240 continue; 3241 to->to_flags |= TOF_SACKPERM; 3242 break; 3243 case TCPOPT_SACK: 3244 if (optlen <= 2 || (optlen - 2) % TCPOLEN_SACK != 0) 3245 continue; 3246 if (flags & TO_SYN) 3247 continue; 3248 to->to_flags |= TOF_SACK; 3249 to->to_nsacks = (optlen - 2) / TCPOLEN_SACK; 3250 to->to_sacks = cp + 2; 3251 TCPSTAT_INC(tcps_sack_rcv_blocks); 3252 break; 3253 default: 3254 continue; 3255 } 3256 } 3257} 3258 3259/* 3260 * Pull out of band byte out of a segment so 3261 * it doesn't appear in the user's data queue. 3262 * It is still reflected in the segment length for 3263 * sequencing purposes. 3264 */ 3265static void 3266tcp_pulloutofband(struct socket *so, struct tcphdr *th, struct mbuf *m, 3267 int off) 3268{ 3269 int cnt = off + th->th_urp - 1; 3270 3271 while (cnt >= 0) { 3272 if (m->m_len > cnt) { 3273 char *cp = mtod(m, caddr_t) + cnt; 3274 struct tcpcb *tp = sototcpcb(so); 3275 3276 INP_WLOCK_ASSERT(tp->t_inpcb); 3277 3278 tp->t_iobc = *cp; 3279 tp->t_oobflags |= TCPOOB_HAVEDATA; 3280 bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); 3281 m->m_len--; 3282 if (m->m_flags & M_PKTHDR) 3283 m->m_pkthdr.len--; 3284 return; 3285 } 3286 cnt -= m->m_len; 3287 m = m->m_next; 3288 if (m == NULL) 3289 break; 3290 } 3291 panic("tcp_pulloutofband"); 3292} 3293 3294/* 3295 * Collect new round-trip time estimate 3296 * and update averages and current timeout. 3297 */ 3298static void 3299tcp_xmit_timer(struct tcpcb *tp, int rtt) 3300{ 3301 int delta; 3302 3303 INP_WLOCK_ASSERT(tp->t_inpcb); 3304 3305 TCPSTAT_INC(tcps_rttupdated); 3306 tp->t_rttupdated++; 3307 if (tp->t_srtt != 0) { 3308 /* 3309 * srtt is stored as fixed point with 5 bits after the 3310 * binary point (i.e., scaled by 8). The following magic 3311 * is equivalent to the smoothing algorithm in rfc793 with 3312 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed 3313 * point). Adjust rtt to origin 0. 3314 */ 3315 delta = ((rtt - 1) << TCP_DELTA_SHIFT) 3316 - (tp->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT)); 3317 3318 if ((tp->t_srtt += delta) <= 0) 3319 tp->t_srtt = 1; 3320 3321 /* 3322 * We accumulate a smoothed rtt variance (actually, a 3323 * smoothed mean difference), then set the retransmit 3324 * timer to smoothed rtt + 4 times the smoothed variance. 3325 * rttvar is stored as fixed point with 4 bits after the 3326 * binary point (scaled by 16). The following is 3327 * equivalent to rfc793 smoothing with an alpha of .75 3328 * (rttvar = rttvar*3/4 + |delta| / 4). This replaces 3329 * rfc793's wired-in beta. 3330 */ 3331 if (delta < 0) 3332 delta = -delta; 3333 delta -= tp->t_rttvar >> (TCP_RTTVAR_SHIFT - TCP_DELTA_SHIFT); 3334 if ((tp->t_rttvar += delta) <= 0) 3335 tp->t_rttvar = 1; 3336 if (tp->t_rttbest > tp->t_srtt + tp->t_rttvar) 3337 tp->t_rttbest = tp->t_srtt + tp->t_rttvar; 3338 } else { 3339 /* 3340 * No rtt measurement yet - use the unsmoothed rtt. 3341 * Set the variance to half the rtt (so our first 3342 * retransmit happens at 3*rtt). 3343 */ 3344 tp->t_srtt = rtt << TCP_RTT_SHIFT; 3345 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1); 3346 tp->t_rttbest = tp->t_srtt + tp->t_rttvar; 3347 } 3348 tp->t_rtttime = 0; 3349 tp->t_rxtshift = 0; 3350 3351 /* 3352 * the retransmit should happen at rtt + 4 * rttvar. 3353 * Because of the way we do the smoothing, srtt and rttvar 3354 * will each average +1/2 tick of bias. When we compute 3355 * the retransmit timer, we want 1/2 tick of rounding and 3356 * 1 extra tick because of +-1/2 tick uncertainty in the 3357 * firing of the timer. The bias will give us exactly the 3358 * 1.5 tick we need. But, because the bias is 3359 * statistical, we have to test that we don't drop below 3360 * the minimum feasible timer (which is 2 ticks). 3361 */ 3362 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), 3363 max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX); 3364 3365 /* 3366 * We received an ack for a packet that wasn't retransmitted; 3367 * it is probably safe to discard any error indications we've 3368 * received recently. This isn't quite right, but close enough 3369 * for now (a route might have failed after we sent a segment, 3370 * and the return path might not be symmetrical). 3371 */ 3372 tp->t_softerror = 0; 3373} 3374 3375/* 3376 * Determine a reasonable value for maxseg size. 3377 * If the route is known, check route for mtu. 3378 * If none, use an mss that can be handled on the outgoing interface 3379 * without forcing IP to fragment. If no route is found, route has no mtu, 3380 * or the destination isn't local, use a default, hopefully conservative 3381 * size (usually 512 or the default IP max size, but no more than the mtu 3382 * of the interface), as we can't discover anything about intervening 3383 * gateways or networks. We also initialize the congestion/slow start 3384 * window to be a single segment if the destination isn't local. 3385 * While looking at the routing entry, we also initialize other path-dependent 3386 * parameters from pre-set or cached values in the routing entry. 3387 * 3388 * Also take into account the space needed for options that we 3389 * send regularly. Make maxseg shorter by that amount to assure 3390 * that we can send maxseg amount of data even when the options 3391 * are present. Store the upper limit of the length of options plus 3392 * data in maxopd. 3393 * 3394 * NOTE that this routine is only called when we process an incoming 3395 * segment, or an ICMP need fragmentation datagram. Outgoing SYN/ACK MSS 3396 * settings are handled in tcp_mssopt(). 3397 */ 3398void 3399tcp_mss_update(struct tcpcb *tp, int offer, int mtuoffer, 3400 struct hc_metrics_lite *metricptr, struct tcp_ifcap *cap) 3401{ 3402 int mss = 0; 3403 u_long maxmtu = 0; 3404 struct inpcb *inp = tp->t_inpcb; 3405 struct hc_metrics_lite metrics; 3406 int origoffer; 3407#ifdef INET6 3408 int isipv6 = ((inp->inp_vflag & INP_IPV6) != 0) ? 1 : 0; 3409 size_t min_protoh = isipv6 ? 3410 sizeof (struct ip6_hdr) + sizeof (struct tcphdr) : 3411 sizeof (struct tcpiphdr); 3412#else 3413 const size_t min_protoh = sizeof(struct tcpiphdr); 3414#endif 3415 3416 INP_WLOCK_ASSERT(tp->t_inpcb); 3417 3418 if (mtuoffer != -1) { 3419 KASSERT(offer == -1, ("%s: conflict", __func__)); 3420 offer = mtuoffer - min_protoh; 3421 } 3422 origoffer = offer; 3423 3424 /* Initialize. */ 3425#ifdef INET6 3426 if (isipv6) { 3427 maxmtu = tcp_maxmtu6(&inp->inp_inc, cap); 3428 tp->t_maxopd = tp->t_maxseg = V_tcp_v6mssdflt; 3429 } 3430#endif 3431#if defined(INET) && defined(INET6) 3432 else 3433#endif 3434#ifdef INET 3435 { 3436 maxmtu = tcp_maxmtu(&inp->inp_inc, cap); 3437 tp->t_maxopd = tp->t_maxseg = V_tcp_mssdflt; 3438 } 3439#endif 3440 3441 /* 3442 * No route to sender, stay with default mss and return. 3443 */ 3444 if (maxmtu == 0) { 3445 /* 3446 * In case we return early we need to initialize metrics 3447 * to a defined state as tcp_hc_get() would do for us 3448 * if there was no cache hit. 3449 */ 3450 if (metricptr != NULL) 3451 bzero(metricptr, sizeof(struct hc_metrics_lite)); 3452 return; 3453 } 3454 3455 /* What have we got? */ 3456 switch (offer) { 3457 case 0: 3458 /* 3459 * Offer == 0 means that there was no MSS on the SYN 3460 * segment, in this case we use tcp_mssdflt as 3461 * already assigned to t_maxopd above. 3462 */ 3463 offer = tp->t_maxopd; 3464 break; 3465 3466 case -1: 3467 /* 3468 * Offer == -1 means that we didn't receive SYN yet. 3469 */ 3470 /* FALLTHROUGH */ 3471 3472 default: 3473 /* 3474 * Prevent DoS attack with too small MSS. Round up 3475 * to at least minmss. 3476 */ 3477 offer = max(offer, V_tcp_minmss); 3478 } 3479 3480 /* 3481 * rmx information is now retrieved from tcp_hostcache. 3482 */ 3483 tcp_hc_get(&inp->inp_inc, &metrics); 3484 if (metricptr != NULL) 3485 bcopy(&metrics, metricptr, sizeof(struct hc_metrics_lite)); 3486 3487 /* 3488 * If there's a discovered mtu int tcp hostcache, use it 3489 * else, use the link mtu. 3490 */ 3491 if (metrics.rmx_mtu) 3492 mss = min(metrics.rmx_mtu, maxmtu) - min_protoh; 3493 else { 3494#ifdef INET6 3495 if (isipv6) { 3496 mss = maxmtu - min_protoh; 3497 if (!V_path_mtu_discovery && 3498 !in6_localaddr(&inp->in6p_faddr)) 3499 mss = min(mss, V_tcp_v6mssdflt); 3500 } 3501#endif 3502#if defined(INET) && defined(INET6) 3503 else 3504#endif 3505#ifdef INET 3506 { 3507 mss = maxmtu - min_protoh; 3508 if (!V_path_mtu_discovery && 3509 !in_localaddr(inp->inp_faddr)) 3510 mss = min(mss, V_tcp_mssdflt); 3511 } 3512#endif 3513 /* 3514 * XXX - The above conditional (mss = maxmtu - min_protoh) 3515 * probably violates the TCP spec. 3516 * The problem is that, since we don't know the 3517 * other end's MSS, we are supposed to use a conservative 3518 * default. But, if we do that, then MTU discovery will 3519 * never actually take place, because the conservative 3520 * default is much less than the MTUs typically seen 3521 * on the Internet today. For the moment, we'll sweep 3522 * this under the carpet. 3523 * 3524 * The conservative default might not actually be a problem 3525 * if the only case this occurs is when sending an initial 3526 * SYN with options and data to a host we've never talked 3527 * to before. Then, they will reply with an MSS value which 3528 * will get recorded and the new parameters should get 3529 * recomputed. For Further Study. 3530 */ 3531 } 3532 mss = min(mss, offer); 3533 3534 /* 3535 * Sanity check: make sure that maxopd will be large 3536 * enough to allow some data on segments even if the 3537 * all the option space is used (40bytes). Otherwise 3538 * funny things may happen in tcp_output. 3539 */ 3540 mss = max(mss, 64); 3541 3542 /* 3543 * maxopd stores the maximum length of data AND options 3544 * in a segment; maxseg is the amount of data in a normal 3545 * segment. We need to store this value (maxopd) apart 3546 * from maxseg, because now every segment carries options 3547 * and thus we normally have somewhat less data in segments. 3548 */ 3549 tp->t_maxopd = mss; 3550 3551 /* 3552 * origoffer==-1 indicates that no segments were received yet. 3553 * In this case we just guess. 3554 */ 3555 if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP && 3556 (origoffer == -1 || 3557 (tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP)) 3558 mss -= TCPOLEN_TSTAMP_APPA; 3559 3560 tp->t_maxseg = mss; 3561} 3562 3563void 3564tcp_mss(struct tcpcb *tp, int offer) 3565{ 3566 int mss; 3567 u_long bufsize; 3568 struct inpcb *inp; 3569 struct socket *so; 3570 struct hc_metrics_lite metrics; 3571 struct tcp_ifcap cap; 3572 3573 KASSERT(tp != NULL, ("%s: tp == NULL", __func__)); 3574 3575 bzero(&cap, sizeof(cap)); 3576 tcp_mss_update(tp, offer, -1, &metrics, &cap); 3577 3578 mss = tp->t_maxseg; 3579 inp = tp->t_inpcb; 3580 3581 /* 3582 * If there's a pipesize, change the socket buffer to that size, 3583 * don't change if sb_hiwat is different than default (then it 3584 * has been changed on purpose with setsockopt). 3585 * Make the socket buffers an integral number of mss units; 3586 * if the mss is larger than the socket buffer, decrease the mss. 3587 */ 3588 so = inp->inp_socket; 3589 SOCKBUF_LOCK(&so->so_snd); 3590 if ((so->so_snd.sb_hiwat == V_tcp_sendspace) && metrics.rmx_sendpipe) 3591 bufsize = metrics.rmx_sendpipe; 3592 else 3593 bufsize = so->so_snd.sb_hiwat; 3594 if (bufsize < mss) 3595 mss = bufsize; 3596 else { 3597 bufsize = roundup(bufsize, mss); 3598 if (bufsize > sb_max) 3599 bufsize = sb_max; 3600 if (bufsize > so->so_snd.sb_hiwat) 3601 (void)sbreserve_locked(&so->so_snd, bufsize, so, NULL); 3602 } 3603 SOCKBUF_UNLOCK(&so->so_snd); 3604 tp->t_maxseg = mss; 3605 3606 SOCKBUF_LOCK(&so->so_rcv); 3607 if ((so->so_rcv.sb_hiwat == V_tcp_recvspace) && metrics.rmx_recvpipe) 3608 bufsize = metrics.rmx_recvpipe; 3609 else 3610 bufsize = so->so_rcv.sb_hiwat; 3611 if (bufsize > mss) { 3612 bufsize = roundup(bufsize, mss); 3613 if (bufsize > sb_max) 3614 bufsize = sb_max; 3615 if (bufsize > so->so_rcv.sb_hiwat) 3616 (void)sbreserve_locked(&so->so_rcv, bufsize, so, NULL); 3617 } 3618 SOCKBUF_UNLOCK(&so->so_rcv); 3619 3620 /* Check the interface for TSO capabilities. */ 3621 if (cap.ifcap & CSUM_TSO) { 3622 tp->t_flags |= TF_TSO; 3623 tp->t_tsomax = cap.tsomax; 3624 tp->t_tsomaxsegcount = cap.tsomaxsegcount; 3625 tp->t_tsomaxsegsize = cap.tsomaxsegsize; 3626 } 3627} 3628 3629/* 3630 * Determine the MSS option to send on an outgoing SYN. 3631 */ 3632int 3633tcp_mssopt(struct in_conninfo *inc) 3634{ 3635 int mss = 0; 3636 u_long maxmtu = 0; 3637 u_long thcmtu = 0; 3638 size_t min_protoh; 3639 3640 KASSERT(inc != NULL, ("tcp_mssopt with NULL in_conninfo pointer")); 3641 3642#ifdef INET6 3643 if (inc->inc_flags & INC_ISIPV6) { 3644 mss = V_tcp_v6mssdflt; 3645 maxmtu = tcp_maxmtu6(inc, NULL); 3646 min_protoh = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 3647 } 3648#endif 3649#if defined(INET) && defined(INET6) 3650 else 3651#endif 3652#ifdef INET 3653 { 3654 mss = V_tcp_mssdflt; 3655 maxmtu = tcp_maxmtu(inc, NULL); 3656 min_protoh = sizeof(struct tcpiphdr); 3657 } 3658#endif 3659#if defined(INET6) || defined(INET) 3660 thcmtu = tcp_hc_getmtu(inc); /* IPv4 and IPv6 */ 3661#endif 3662 3663 if (maxmtu && thcmtu) 3664 mss = min(maxmtu, thcmtu) - min_protoh; 3665 else if (maxmtu || thcmtu) 3666 mss = max(maxmtu, thcmtu) - min_protoh; 3667 3668 return (mss); 3669} 3670 3671 3672/* 3673 * On a partial ack arrives, force the retransmission of the 3674 * next unacknowledged segment. Do not clear tp->t_dupacks. 3675 * By setting snd_nxt to ti_ack, this forces retransmission timer to 3676 * be started again. 3677 */ 3678static void 3679tcp_newreno_partial_ack(struct tcpcb *tp, struct tcphdr *th) 3680{ 3681 tcp_seq onxt = tp->snd_nxt; 3682 u_long ocwnd = tp->snd_cwnd; 3683 3684 INP_WLOCK_ASSERT(tp->t_inpcb); 3685 3686 tcp_timer_activate(tp, TT_REXMT, 0); 3687 tp->t_rtttime = 0; 3688 tp->snd_nxt = th->th_ack; 3689 /* 3690 * Set snd_cwnd to one segment beyond acknowledged offset. 3691 * (tp->snd_una has not yet been updated when this function is called.) 3692 */ 3693 tp->snd_cwnd = tp->t_maxseg + BYTES_THIS_ACK(tp, th); 3694 tp->t_flags |= TF_ACKNOW; 3695 (void) tcp_output(tp); 3696 tp->snd_cwnd = ocwnd; 3697 if (SEQ_GT(onxt, tp->snd_nxt)) 3698 tp->snd_nxt = onxt; 3699 /* 3700 * Partial window deflation. Relies on fact that tp->snd_una 3701 * not updated yet. 3702 */ 3703 if (tp->snd_cwnd > BYTES_THIS_ACK(tp, th)) 3704 tp->snd_cwnd -= BYTES_THIS_ACK(tp, th); 3705 else 3706 tp->snd_cwnd = 0; 3707 tp->snd_cwnd += tp->t_maxseg; 3708} 3709