1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995 5 * The Regents of the University of California. All rights reserved. 6 * Copyright (c) 2007-2008,2010 7 * Swinburne University of Technology, Melbourne, Australia. 8 * Copyright (c) 2009-2010 Lawrence Stewart <lstewart@freebsd.org> 9 * Copyright (c) 2010 The FreeBSD Foundation 10 * Copyright (c) 2010-2011 Juniper Networks, Inc. 11 * All rights reserved. 12 * 13 * Portions of this software were developed at the Centre for Advanced Internet 14 * Architectures, Swinburne University of Technology, by Lawrence Stewart, 15 * James Healy and David Hayes, made possible in part by a grant from the Cisco 16 * University Research Program Fund at Community Foundation Silicon Valley. 17 * 18 * Portions of this software were developed at the Centre for Advanced 19 * Internet Architectures, Swinburne University of Technology, Melbourne, 20 * Australia by David Hayes under sponsorship from the FreeBSD Foundation. 21 * 22 * Portions of this software were developed by Robert N. M. Watson under 23 * contract to Juniper Networks, Inc. 24 * 25 * Redistribution and use in source and binary forms, with or without 26 * modification, are permitted provided that the following conditions 27 * are met: 28 * 1. Redistributions of source code must retain the above copyright 29 * notice, this list of conditions and the following disclaimer. 30 * 2. Redistributions in binary form must reproduce the above copyright 31 * notice, this list of conditions and the following disclaimer in the 32 * documentation and/or other materials provided with the distribution. 33 * 3. Neither the name of the University nor the names of its contributors 34 * may be used to endorse or promote products derived from this software 35 * without specific prior written permission. 36 * 37 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 38 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 39 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 40 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 41 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 42 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 43 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 44 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 45 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 46 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 47 * SUCH DAMAGE. 48 * 49 * @(#)tcp_input.c 8.12 (Berkeley) 5/24/95 50 */ 51 52 #include <sys/cdefs.h> 53 __FBSDID("$FreeBSD$"); 54 55 #include "opt_inet.h" 56 #include "opt_inet6.h" 57 #include "opt_ipsec.h" 58 #include "opt_tcpdebug.h" 59 60 #include <sys/param.h> 61 #include <sys/kernel.h> 62 #ifdef TCP_HHOOK 63 #include <sys/hhook.h> 64 #endif 65 #include <sys/malloc.h> 66 #include <sys/mbuf.h> 67 #include <sys/proc.h> /* for proc0 declaration */ 68 #include <sys/protosw.h> 69 #include <sys/sdt.h> 70 #include <sys/signalvar.h> 71 #include <sys/socket.h> 72 #include <sys/socketvar.h> 73 #include <sys/sysctl.h> 74 #include <sys/syslog.h> 75 #include <sys/systm.h> 76 77 #include <machine/cpu.h> /* before tcp_seq.h, for tcp_random18() */ 78 79 #include <vm/uma.h> 80 81 #include <net/if.h> 82 #include <net/if_var.h> 83 #include <net/route.h> 84 #include <net/vnet.h> 85 86 #define TCPSTATES /* for logging */ 87 88 #include <netinet/in.h> 89 #include <netinet/in_kdtrace.h> 90 #include <netinet/in_pcb.h> 91 #include <netinet/in_systm.h> 92 #include <netinet/ip.h> 93 #include <netinet/ip_icmp.h> /* required for icmp_var.h */ 94 #include <netinet/icmp_var.h> /* for ICMP_BANDLIM */ 95 #include <netinet/ip_var.h> 96 #include <netinet/ip_options.h> 97 #include <netinet/ip6.h> 98 #include <netinet/icmp6.h> 99 #include <netinet6/in6_pcb.h> 100 #include <netinet6/in6_var.h> 101 #include <netinet6/ip6_var.h> 102 #include <netinet6/nd6.h> 103 #ifdef TCP_RFC7413 104 #include <netinet/tcp_fastopen.h> 105 #endif 106 #include <netinet/tcp.h> 107 #include <netinet/tcp_fsm.h> 108 #include <netinet/tcp_seq.h> 109 #include <netinet/tcp_timer.h> 110 #include <netinet/tcp_var.h> 111 #include <netinet6/tcp6_var.h> 112 #include <netinet/tcpip.h> 113 #include <netinet/cc/cc.h> 114 #ifdef TCPPCAP 115 #include <netinet/tcp_pcap.h> 116 #endif 117 #include <netinet/tcp_syncache.h> 118 #ifdef TCPDEBUG 119 #include <netinet/tcp_debug.h> 120 #endif /* TCPDEBUG */ 121 #ifdef TCP_OFFLOAD 122 #include <netinet/tcp_offload.h> 123 #endif 124 125 #include <netipsec/ipsec_support.h> 126 127 #include <machine/in_cksum.h> 128 129 #include <security/mac/mac_framework.h> 130 131 const int tcprexmtthresh = 3; 132 133 int tcp_log_in_vain = 0; 134 SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_in_vain, CTLFLAG_RW, 135 &tcp_log_in_vain, 0, 136 "Log all incoming TCP segments to closed ports"); 137 138 VNET_DEFINE(int, blackhole) = 0; 139 #define V_blackhole VNET(blackhole) 140 SYSCTL_INT(_net_inet_tcp, OID_AUTO, blackhole, CTLFLAG_VNET | CTLFLAG_RW, 141 &VNET_NAME(blackhole), 0, 142 "Do not send RST on segments to closed ports"); 143 144 VNET_DEFINE(int, tcp_delack_enabled) = 1; 145 SYSCTL_INT(_net_inet_tcp, OID_AUTO, delayed_ack, CTLFLAG_VNET | CTLFLAG_RW, 146 &VNET_NAME(tcp_delack_enabled), 0, 147 "Delay ACK to try and piggyback it onto a data packet"); 148 149 VNET_DEFINE(int, drop_synfin) = 0; 150 SYSCTL_INT(_net_inet_tcp, OID_AUTO, drop_synfin, CTLFLAG_VNET | CTLFLAG_RW, 151 &VNET_NAME(drop_synfin), 0, 152 "Drop TCP packets with SYN+FIN set"); 153 154 VNET_DEFINE(int, tcp_do_rfc6675_pipe) = 0; 155 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc6675_pipe, CTLFLAG_VNET | CTLFLAG_RW, 156 &VNET_NAME(tcp_do_rfc6675_pipe), 0, 157 "Use calculated pipe/in-flight bytes per RFC 6675"); 158 159 VNET_DEFINE(int, tcp_do_rfc3042) = 1; 160 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3042, CTLFLAG_VNET | CTLFLAG_RW, 161 &VNET_NAME(tcp_do_rfc3042), 0, 162 "Enable RFC 3042 (Limited Transmit)"); 163 164 VNET_DEFINE(int, tcp_do_rfc3390) = 1; 165 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3390, CTLFLAG_VNET | CTLFLAG_RW, 166 &VNET_NAME(tcp_do_rfc3390), 0, 167 "Enable RFC 3390 (Increasing TCP's Initial Congestion Window)"); 168 169 VNET_DEFINE(int, tcp_initcwnd_segments) = 10; 170 SYSCTL_INT(_net_inet_tcp, OID_AUTO, initcwnd_segments, 171 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(tcp_initcwnd_segments), 0, 172 "Slow-start flight size (initial congestion window) in number of segments"); 173 174 VNET_DEFINE(int, tcp_do_rfc3465) = 1; 175 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3465, CTLFLAG_VNET | CTLFLAG_RW, 176 &VNET_NAME(tcp_do_rfc3465), 0, 177 "Enable RFC 3465 (Appropriate Byte Counting)"); 178 179 VNET_DEFINE(int, tcp_abc_l_var) = 2; 180 SYSCTL_INT(_net_inet_tcp, OID_AUTO, abc_l_var, CTLFLAG_VNET | CTLFLAG_RW, 181 &VNET_NAME(tcp_abc_l_var), 2, 182 "Cap the max cwnd increment during slow-start to this number of segments"); 183 184 static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, ecn, CTLFLAG_RW, 0, "TCP ECN"); 185 186 VNET_DEFINE(int, tcp_do_ecn) = 2; 187 SYSCTL_INT(_net_inet_tcp_ecn, OID_AUTO, enable, CTLFLAG_VNET | CTLFLAG_RW, 188 &VNET_NAME(tcp_do_ecn), 0, 189 "TCP ECN support"); 190 191 VNET_DEFINE(int, tcp_ecn_maxretries) = 1; 192 SYSCTL_INT(_net_inet_tcp_ecn, OID_AUTO, maxretries, CTLFLAG_VNET | CTLFLAG_RW, 193 &VNET_NAME(tcp_ecn_maxretries), 0, 194 "Max retries before giving up on ECN"); 195 196 VNET_DEFINE(int, tcp_insecure_syn) = 0; 197 SYSCTL_INT(_net_inet_tcp, OID_AUTO, insecure_syn, CTLFLAG_VNET | CTLFLAG_RW, 198 &VNET_NAME(tcp_insecure_syn), 0, 199 "Follow RFC793 instead of RFC5961 criteria for accepting SYN packets"); 200 201 VNET_DEFINE(int, tcp_insecure_rst) = 0; 202 SYSCTL_INT(_net_inet_tcp, OID_AUTO, insecure_rst, CTLFLAG_VNET | CTLFLAG_RW, 203 &VNET_NAME(tcp_insecure_rst), 0, 204 "Follow RFC793 instead of RFC5961 criteria for accepting RST packets"); 205 206 VNET_DEFINE(int, tcp_recvspace) = 1024*64; 207 #define V_tcp_recvspace VNET(tcp_recvspace) 208 SYSCTL_INT(_net_inet_tcp, TCPCTL_RECVSPACE, recvspace, CTLFLAG_VNET | CTLFLAG_RW, 209 &VNET_NAME(tcp_recvspace), 0, "Initial receive socket buffer size"); 210 211 VNET_DEFINE(int, tcp_do_autorcvbuf) = 1; 212 SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_auto, CTLFLAG_VNET | CTLFLAG_RW, 213 &VNET_NAME(tcp_do_autorcvbuf), 0, 214 "Enable automatic receive buffer sizing"); 215 216 VNET_DEFINE(int, tcp_autorcvbuf_inc) = 16*1024; 217 SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_inc, CTLFLAG_VNET | CTLFLAG_RW, 218 &VNET_NAME(tcp_autorcvbuf_inc), 0, 219 "Incrementor step size of automatic receive buffer"); 220 221 VNET_DEFINE(int, tcp_autorcvbuf_max) = 2*1024*1024; 222 SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_max, CTLFLAG_VNET | CTLFLAG_RW, 223 &VNET_NAME(tcp_autorcvbuf_max), 0, 224 "Max size of automatic receive buffer"); 225 226 VNET_DEFINE(struct inpcbhead, tcb); 227 #define tcb6 tcb /* for KAME src sync over BSD*'s */ 228 VNET_DEFINE(struct inpcbinfo, tcbinfo); 229 230 /* 231 * TCP statistics are stored in an array of counter(9)s, which size matches 232 * size of struct tcpstat. TCP running connection count is a regular array. 233 */ 234 VNET_PCPUSTAT_DEFINE(struct tcpstat, tcpstat); 235 SYSCTL_VNET_PCPUSTAT(_net_inet_tcp, TCPCTL_STATS, stats, struct tcpstat, 236 tcpstat, "TCP statistics (struct tcpstat, netinet/tcp_var.h)"); 237 VNET_DEFINE(counter_u64_t, tcps_states[TCP_NSTATES]); 238 SYSCTL_COUNTER_U64_ARRAY(_net_inet_tcp, TCPCTL_STATES, states, CTLFLAG_RD | 239 CTLFLAG_VNET, &VNET_NAME(tcps_states)[0], TCP_NSTATES, 240 "TCP connection counts by TCP state"); 241 242 static void 243 tcp_vnet_init(const void *unused) 244 { 245 246 COUNTER_ARRAY_ALLOC(V_tcps_states, TCP_NSTATES, M_WAITOK); 247 VNET_PCPUSTAT_ALLOC(tcpstat, M_WAITOK); 248 } 249 VNET_SYSINIT(tcp_vnet_init, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY, 250 tcp_vnet_init, NULL); 251 252 #ifdef VIMAGE 253 static void 254 tcp_vnet_uninit(const void *unused) 255 { 256 257 COUNTER_ARRAY_FREE(V_tcps_states, TCP_NSTATES); 258 VNET_PCPUSTAT_FREE(tcpstat); 259 } 260 VNET_SYSUNINIT(tcp_vnet_uninit, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY, 261 tcp_vnet_uninit, NULL); 262 #endif /* VIMAGE */ 263 264 /* 265 * Kernel module interface for updating tcpstat. The argument is an index 266 * into tcpstat treated as an array. 267 */ 268 void 269 kmod_tcpstat_inc(int statnum) 270 { 271 272 counter_u64_add(VNET(tcpstat)[statnum], 1); 273 } 274 275 #ifdef TCP_HHOOK 276 /* 277 * Wrapper for the TCP established input helper hook. 278 */ 279 void 280 hhook_run_tcp_est_in(struct tcpcb *tp, struct tcphdr *th, struct tcpopt *to) 281 { 282 struct tcp_hhook_data hhook_data; 283 284 if (V_tcp_hhh[HHOOK_TCP_EST_IN]->hhh_nhooks > 0) { 285 hhook_data.tp = tp; 286 hhook_data.th = th; 287 hhook_data.to = to; 288 289 hhook_run_hooks(V_tcp_hhh[HHOOK_TCP_EST_IN], &hhook_data, 290 tp->osd); 291 } 292 } 293 #endif 294 295 /* 296 * CC wrapper hook functions 297 */ 298 void 299 cc_ack_received(struct tcpcb *tp, struct tcphdr *th, uint16_t nsegs, 300 uint16_t type) 301 { 302 INP_WLOCK_ASSERT(tp->t_inpcb); 303 304 tp->ccv->nsegs = nsegs; 305 tp->ccv->bytes_this_ack = BYTES_THIS_ACK(tp, th); 306 if (tp->snd_cwnd <= tp->snd_wnd) 307 tp->ccv->flags |= CCF_CWND_LIMITED; 308 else 309 tp->ccv->flags &= ~CCF_CWND_LIMITED; 310 311 if (type == CC_ACK) { 312 if (tp->snd_cwnd > tp->snd_ssthresh) { 313 tp->t_bytes_acked += min(tp->ccv->bytes_this_ack, 314 nsegs * V_tcp_abc_l_var * tcp_maxseg(tp)); 315 if (tp->t_bytes_acked >= tp->snd_cwnd) { 316 tp->t_bytes_acked -= tp->snd_cwnd; 317 tp->ccv->flags |= CCF_ABC_SENTAWND; 318 } 319 } else { 320 tp->ccv->flags &= ~CCF_ABC_SENTAWND; 321 tp->t_bytes_acked = 0; 322 } 323 } 324 325 if (CC_ALGO(tp)->ack_received != NULL) { 326 /* XXXLAS: Find a way to live without this */ 327 tp->ccv->curack = th->th_ack; 328 CC_ALGO(tp)->ack_received(tp->ccv, type); 329 } 330 } 331 332 void 333 cc_conn_init(struct tcpcb *tp) 334 { 335 struct hc_metrics_lite metrics; 336 struct inpcb *inp = tp->t_inpcb; 337 u_int maxseg; 338 int rtt; 339 340 INP_WLOCK_ASSERT(tp->t_inpcb); 341 342 tcp_hc_get(&inp->inp_inc, &metrics); 343 maxseg = tcp_maxseg(tp); 344 345 if (tp->t_srtt == 0 && (rtt = metrics.rmx_rtt)) { 346 tp->t_srtt = rtt; 347 tp->t_rttbest = tp->t_srtt + TCP_RTT_SCALE; 348 TCPSTAT_INC(tcps_usedrtt); 349 if (metrics.rmx_rttvar) { 350 tp->t_rttvar = metrics.rmx_rttvar; 351 TCPSTAT_INC(tcps_usedrttvar); 352 } else { 353 /* default variation is +- 1 rtt */ 354 tp->t_rttvar = 355 tp->t_srtt * TCP_RTTVAR_SCALE / TCP_RTT_SCALE; 356 } 357 TCPT_RANGESET(tp->t_rxtcur, 358 ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1, 359 tp->t_rttmin, TCPTV_REXMTMAX); 360 } 361 if (metrics.rmx_ssthresh) { 362 /* 363 * There's some sort of gateway or interface 364 * buffer limit on the path. Use this to set 365 * the slow start threshold, but set the 366 * threshold to no less than 2*mss. 367 */ 368 tp->snd_ssthresh = max(2 * maxseg, metrics.rmx_ssthresh); 369 TCPSTAT_INC(tcps_usedssthresh); 370 } 371 372 /* 373 * Set the initial slow-start flight size. 374 * 375 * RFC5681 Section 3.1 specifies the default conservative values. 376 * RFC3390 specifies slightly more aggressive values. 377 * RFC6928 increases it to ten segments. 378 * Support for user specified value for initial flight size. 379 * 380 * If a SYN or SYN/ACK was lost and retransmitted, we have to 381 * reduce the initial CWND to one segment as congestion is likely 382 * requiring us to be cautious. 383 */ 384 if (tp->snd_cwnd == 1) 385 tp->snd_cwnd = maxseg; /* SYN(-ACK) lost */ 386 else if (V_tcp_initcwnd_segments) 387 tp->snd_cwnd = min(V_tcp_initcwnd_segments * maxseg, 388 max(2 * maxseg, V_tcp_initcwnd_segments * 1460)); 389 else if (V_tcp_do_rfc3390) 390 tp->snd_cwnd = min(4 * maxseg, max(2 * maxseg, 4380)); 391 else { 392 /* Per RFC5681 Section 3.1 */ 393 if (maxseg > 2190) 394 tp->snd_cwnd = 2 * maxseg; 395 else if (maxseg > 1095) 396 tp->snd_cwnd = 3 * maxseg; 397 else 398 tp->snd_cwnd = 4 * maxseg; 399 } 400 401 if (CC_ALGO(tp)->conn_init != NULL) 402 CC_ALGO(tp)->conn_init(tp->ccv); 403 } 404 405 void inline 406 cc_cong_signal(struct tcpcb *tp, struct tcphdr *th, uint32_t type) 407 { 408 u_int maxseg; 409 410 INP_WLOCK_ASSERT(tp->t_inpcb); 411 412 switch(type) { 413 case CC_NDUPACK: 414 if (!IN_FASTRECOVERY(tp->t_flags)) { 415 tp->snd_recover = tp->snd_max; 416 if (tp->t_flags & TF_ECN_PERMIT) 417 tp->t_flags |= TF_ECN_SND_CWR; 418 } 419 break; 420 case CC_ECN: 421 if (!IN_CONGRECOVERY(tp->t_flags)) { 422 TCPSTAT_INC(tcps_ecn_rcwnd); 423 tp->snd_recover = tp->snd_max; 424 if (tp->t_flags & TF_ECN_PERMIT) 425 tp->t_flags |= TF_ECN_SND_CWR; 426 } 427 break; 428 case CC_RTO: 429 maxseg = tcp_maxseg(tp); 430 tp->t_dupacks = 0; 431 tp->t_bytes_acked = 0; 432 EXIT_RECOVERY(tp->t_flags); 433 tp->snd_ssthresh = max(2, min(tp->snd_wnd, tp->snd_cwnd) / 2 / 434 maxseg) * maxseg; 435 tp->snd_cwnd = maxseg; 436 break; 437 case CC_RTO_ERR: 438 TCPSTAT_INC(tcps_sndrexmitbad); 439 /* RTO was unnecessary, so reset everything. */ 440 tp->snd_cwnd = tp->snd_cwnd_prev; 441 tp->snd_ssthresh = tp->snd_ssthresh_prev; 442 tp->snd_recover = tp->snd_recover_prev; 443 if (tp->t_flags & TF_WASFRECOVERY) 444 ENTER_FASTRECOVERY(tp->t_flags); 445 if (tp->t_flags & TF_WASCRECOVERY) 446 ENTER_CONGRECOVERY(tp->t_flags); 447 tp->snd_nxt = tp->snd_max; 448 tp->t_flags &= ~TF_PREVVALID; 449 tp->t_badrxtwin = 0; 450 break; 451 } 452 453 if (CC_ALGO(tp)->cong_signal != NULL) { 454 if (th != NULL) 455 tp->ccv->curack = th->th_ack; 456 CC_ALGO(tp)->cong_signal(tp->ccv, type); 457 } 458 } 459 460 void inline 461 cc_post_recovery(struct tcpcb *tp, struct tcphdr *th) 462 { 463 INP_WLOCK_ASSERT(tp->t_inpcb); 464 465 /* XXXLAS: KASSERT that we're in recovery? */ 466 467 if (CC_ALGO(tp)->post_recovery != NULL) { 468 tp->ccv->curack = th->th_ack; 469 CC_ALGO(tp)->post_recovery(tp->ccv); 470 } 471 /* XXXLAS: EXIT_RECOVERY ? */ 472 tp->t_bytes_acked = 0; 473 } 474 475 /* 476 * Indicate whether this ack should be delayed. We can delay the ack if 477 * following conditions are met: 478 * - There is no delayed ack timer in progress. 479 * - Our last ack wasn't a 0-sized window. We never want to delay 480 * the ack that opens up a 0-sized window. 481 * - LRO wasn't used for this segment. We make sure by checking that the 482 * segment size is not larger than the MSS. 483 */ 484 #define DELAY_ACK(tp, tlen) \ 485 ((!tcp_timer_active(tp, TT_DELACK) && \ 486 (tp->t_flags & TF_RXWIN0SENT) == 0) && \ 487 (tlen <= tp->t_maxseg) && \ 488 (V_tcp_delack_enabled || (tp->t_flags & TF_NEEDSYN))) 489 490 static void inline 491 cc_ecnpkt_handler(struct tcpcb *tp, struct tcphdr *th, uint8_t iptos) 492 { 493 INP_WLOCK_ASSERT(tp->t_inpcb); 494 495 if (CC_ALGO(tp)->ecnpkt_handler != NULL) { 496 switch (iptos & IPTOS_ECN_MASK) { 497 case IPTOS_ECN_CE: 498 tp->ccv->flags |= CCF_IPHDR_CE; 499 break; 500 case IPTOS_ECN_ECT0: 501 tp->ccv->flags &= ~CCF_IPHDR_CE; 502 break; 503 case IPTOS_ECN_ECT1: 504 tp->ccv->flags &= ~CCF_IPHDR_CE; 505 break; 506 } 507 508 if (th->th_flags & TH_CWR) 509 tp->ccv->flags |= CCF_TCPHDR_CWR; 510 else 511 tp->ccv->flags &= ~CCF_TCPHDR_CWR; 512 513 if (tp->t_flags & TF_DELACK) 514 tp->ccv->flags |= CCF_DELACK; 515 else 516 tp->ccv->flags &= ~CCF_DELACK; 517 518 CC_ALGO(tp)->ecnpkt_handler(tp->ccv); 519 520 if (tp->ccv->flags & CCF_ACKNOW) 521 tcp_timer_activate(tp, TT_DELACK, tcp_delacktime); 522 } 523 } 524 525 /* 526 * TCP input handling is split into multiple parts: 527 * tcp6_input is a thin wrapper around tcp_input for the extended 528 * ip6_protox[] call format in ip6_input 529 * tcp_input handles primary segment validation, inpcb lookup and 530 * SYN processing on listen sockets 531 * tcp_do_segment processes the ACK and text of the segment for 532 * establishing, established and closing connections 533 */ 534 #ifdef INET6 535 int 536 tcp6_input(struct mbuf **mp, int *offp, int proto) 537 { 538 struct mbuf *m = *mp; 539 struct in6_ifaddr *ia6; 540 struct ip6_hdr *ip6; 541 542 IP6_EXTHDR_CHECK(m, *offp, sizeof(struct tcphdr), IPPROTO_DONE); 543 544 /* 545 * draft-itojun-ipv6-tcp-to-anycast 546 * better place to put this in? 547 */ 548 ip6 = mtod(m, struct ip6_hdr *); 549 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */); 550 if (ia6 && (ia6->ia6_flags & IN6_IFF_ANYCAST)) { 551 struct ip6_hdr *ip6; 552 553 ifa_free(&ia6->ia_ifa); 554 ip6 = mtod(m, struct ip6_hdr *); 555 icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR, 556 (caddr_t)&ip6->ip6_dst - (caddr_t)ip6); 557 return (IPPROTO_DONE); 558 } 559 if (ia6) 560 ifa_free(&ia6->ia_ifa); 561 562 return (tcp_input(mp, offp, proto)); 563 } 564 #endif /* INET6 */ 565 566 int 567 tcp_input(struct mbuf **mp, int *offp, int proto) 568 { 569 struct mbuf *m = *mp; 570 struct tcphdr *th = NULL; 571 struct ip *ip = NULL; 572 struct inpcb *inp = NULL; 573 struct tcpcb *tp = NULL; 574 struct socket *so = NULL; 575 u_char *optp = NULL; 576 int off0; 577 int optlen = 0; 578 #ifdef INET 579 int len; 580 #endif 581 int tlen = 0, off; 582 int drop_hdrlen; 583 int thflags; 584 int rstreason = 0; /* For badport_bandlim accounting purposes */ 585 uint8_t iptos; 586 struct m_tag *fwd_tag = NULL; 587 #ifdef INET6 588 struct ip6_hdr *ip6 = NULL; 589 int isipv6; 590 #else 591 const void *ip6 = NULL; 592 #endif /* INET6 */ 593 struct tcpopt to; /* options in this segment */ 594 char *s = NULL; /* address and port logging */ 595 int ti_locked; 596 #ifdef TCPDEBUG 597 /* 598 * The size of tcp_saveipgen must be the size of the max ip header, 599 * now IPv6. 600 */ 601 u_char tcp_saveipgen[IP6_HDR_LEN]; 602 struct tcphdr tcp_savetcp; 603 short ostate = 0; 604 #endif 605 606 #ifdef INET6 607 isipv6 = (mtod(m, struct ip *)->ip_v == 6) ? 1 : 0; 608 #endif 609 610 off0 = *offp; 611 m = *mp; 612 *mp = NULL; 613 to.to_flags = 0; 614 TCPSTAT_INC(tcps_rcvtotal); 615 616 #ifdef INET6 617 if (isipv6) { 618 /* IP6_EXTHDR_CHECK() is already done at tcp6_input(). */ 619 620 if (m->m_len < (sizeof(*ip6) + sizeof(*th))) { 621 m = m_pullup(m, sizeof(*ip6) + sizeof(*th)); 622 if (m == NULL) { 623 TCPSTAT_INC(tcps_rcvshort); 624 return (IPPROTO_DONE); 625 } 626 } 627 628 ip6 = mtod(m, struct ip6_hdr *); 629 th = (struct tcphdr *)((caddr_t)ip6 + off0); 630 tlen = sizeof(*ip6) + ntohs(ip6->ip6_plen) - off0; 631 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID_IPV6) { 632 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 633 th->th_sum = m->m_pkthdr.csum_data; 634 else 635 th->th_sum = in6_cksum_pseudo(ip6, tlen, 636 IPPROTO_TCP, m->m_pkthdr.csum_data); 637 th->th_sum ^= 0xffff; 638 } else 639 th->th_sum = in6_cksum(m, IPPROTO_TCP, off0, tlen); 640 if (th->th_sum) { 641 TCPSTAT_INC(tcps_rcvbadsum); 642 goto drop; 643 } 644 645 /* 646 * Be proactive about unspecified IPv6 address in source. 647 * As we use all-zero to indicate unbounded/unconnected pcb, 648 * unspecified IPv6 address can be used to confuse us. 649 * 650 * Note that packets with unspecified IPv6 destination is 651 * already dropped in ip6_input. 652 */ 653 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 654 /* XXX stat */ 655 goto drop; 656 } 657 iptos = (ntohl(ip6->ip6_flow) >> 20) & 0xff; 658 } 659 #endif 660 #if defined(INET) && defined(INET6) 661 else 662 #endif 663 #ifdef INET 664 { 665 /* 666 * Get IP and TCP header together in first mbuf. 667 * Note: IP leaves IP header in first mbuf. 668 */ 669 if (off0 > sizeof (struct ip)) { 670 ip_stripoptions(m); 671 off0 = sizeof(struct ip); 672 } 673 if (m->m_len < sizeof (struct tcpiphdr)) { 674 if ((m = m_pullup(m, sizeof (struct tcpiphdr))) 675 == NULL) { 676 TCPSTAT_INC(tcps_rcvshort); 677 return (IPPROTO_DONE); 678 } 679 } 680 ip = mtod(m, struct ip *); 681 th = (struct tcphdr *)((caddr_t)ip + off0); 682 tlen = ntohs(ip->ip_len) - off0; 683 684 iptos = ip->ip_tos; 685 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) { 686 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 687 th->th_sum = m->m_pkthdr.csum_data; 688 else 689 th->th_sum = in_pseudo(ip->ip_src.s_addr, 690 ip->ip_dst.s_addr, 691 htonl(m->m_pkthdr.csum_data + tlen + 692 IPPROTO_TCP)); 693 th->th_sum ^= 0xffff; 694 } else { 695 struct ipovly *ipov = (struct ipovly *)ip; 696 697 /* 698 * Checksum extended TCP header and data. 699 */ 700 len = off0 + tlen; 701 bzero(ipov->ih_x1, sizeof(ipov->ih_x1)); 702 ipov->ih_len = htons(tlen); 703 th->th_sum = in_cksum(m, len); 704 /* Reset length for SDT probes. */ 705 ip->ip_len = htons(len); 706 /* Reset TOS bits */ 707 ip->ip_tos = iptos; 708 /* Re-initialization for later version check */ 709 ip->ip_v = IPVERSION; 710 } 711 712 if (th->th_sum) { 713 TCPSTAT_INC(tcps_rcvbadsum); 714 goto drop; 715 } 716 } 717 #endif /* INET */ 718 719 /* 720 * Check that TCP offset makes sense, 721 * pull out TCP options and adjust length. XXX 722 */ 723 off = th->th_off << 2; 724 if (off < sizeof (struct tcphdr) || off > tlen) { 725 TCPSTAT_INC(tcps_rcvbadoff); 726 goto drop; 727 } 728 tlen -= off; /* tlen is used instead of ti->ti_len */ 729 if (off > sizeof (struct tcphdr)) { 730 #ifdef INET6 731 if (isipv6) { 732 IP6_EXTHDR_CHECK(m, off0, off, IPPROTO_DONE); 733 ip6 = mtod(m, struct ip6_hdr *); 734 th = (struct tcphdr *)((caddr_t)ip6 + off0); 735 } 736 #endif 737 #if defined(INET) && defined(INET6) 738 else 739 #endif 740 #ifdef INET 741 { 742 if (m->m_len < sizeof(struct ip) + off) { 743 if ((m = m_pullup(m, sizeof (struct ip) + off)) 744 == NULL) { 745 TCPSTAT_INC(tcps_rcvshort); 746 return (IPPROTO_DONE); 747 } 748 ip = mtod(m, struct ip *); 749 th = (struct tcphdr *)((caddr_t)ip + off0); 750 } 751 } 752 #endif 753 optlen = off - sizeof (struct tcphdr); 754 optp = (u_char *)(th + 1); 755 } 756 thflags = th->th_flags; 757 758 /* 759 * Convert TCP protocol specific fields to host format. 760 */ 761 tcp_fields_to_host(th); 762 763 /* 764 * Delay dropping TCP, IP headers, IPv6 ext headers, and TCP options. 765 */ 766 drop_hdrlen = off0 + off; 767 768 /* 769 * Locate pcb for segment; if we're likely to add or remove a 770 * connection then first acquire pcbinfo lock. There are three cases 771 * where we might discover later we need a write lock despite the 772 * flags: ACKs moving a connection out of the syncache, ACKs for a 773 * connection in TIMEWAIT and SYNs not targeting a listening socket. 774 */ 775 if ((thflags & (TH_FIN | TH_RST)) != 0) { 776 INP_INFO_RLOCK(&V_tcbinfo); 777 ti_locked = TI_RLOCKED; 778 } else 779 ti_locked = TI_UNLOCKED; 780 781 /* 782 * Grab info from PACKET_TAG_IPFORWARD tag prepended to the chain. 783 */ 784 if ( 785 #ifdef INET6 786 (isipv6 && (m->m_flags & M_IP6_NEXTHOP)) 787 #ifdef INET 788 || (!isipv6 && (m->m_flags & M_IP_NEXTHOP)) 789 #endif 790 #endif 791 #if defined(INET) && !defined(INET6) 792 (m->m_flags & M_IP_NEXTHOP) 793 #endif 794 ) 795 fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL); 796 797 findpcb: 798 #ifdef INVARIANTS 799 if (ti_locked == TI_RLOCKED) { 800 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 801 } else { 802 INP_INFO_UNLOCK_ASSERT(&V_tcbinfo); 803 } 804 #endif 805 #ifdef INET6 806 if (isipv6 && fwd_tag != NULL) { 807 struct sockaddr_in6 *next_hop6; 808 809 next_hop6 = (struct sockaddr_in6 *)(fwd_tag + 1); 810 /* 811 * Transparently forwarded. Pretend to be the destination. 812 * Already got one like this? 813 */ 814 inp = in6_pcblookup_mbuf(&V_tcbinfo, 815 &ip6->ip6_src, th->th_sport, &ip6->ip6_dst, th->th_dport, 816 INPLOOKUP_WLOCKPCB, m->m_pkthdr.rcvif, m); 817 if (!inp) { 818 /* 819 * It's new. Try to find the ambushing socket. 820 * Because we've rewritten the destination address, 821 * any hardware-generated hash is ignored. 822 */ 823 inp = in6_pcblookup(&V_tcbinfo, &ip6->ip6_src, 824 th->th_sport, &next_hop6->sin6_addr, 825 next_hop6->sin6_port ? ntohs(next_hop6->sin6_port) : 826 th->th_dport, INPLOOKUP_WILDCARD | 827 INPLOOKUP_WLOCKPCB, m->m_pkthdr.rcvif); 828 } 829 } else if (isipv6) { 830 inp = in6_pcblookup_mbuf(&V_tcbinfo, &ip6->ip6_src, 831 th->th_sport, &ip6->ip6_dst, th->th_dport, 832 INPLOOKUP_WILDCARD | INPLOOKUP_WLOCKPCB, 833 m->m_pkthdr.rcvif, m); 834 } 835 #endif /* INET6 */ 836 #if defined(INET6) && defined(INET) 837 else 838 #endif 839 #ifdef INET 840 if (fwd_tag != NULL) { 841 struct sockaddr_in *next_hop; 842 843 next_hop = (struct sockaddr_in *)(fwd_tag+1); 844 /* 845 * Transparently forwarded. Pretend to be the destination. 846 * already got one like this? 847 */ 848 inp = in_pcblookup_mbuf(&V_tcbinfo, ip->ip_src, th->th_sport, 849 ip->ip_dst, th->th_dport, INPLOOKUP_WLOCKPCB, 850 m->m_pkthdr.rcvif, m); 851 if (!inp) { 852 /* 853 * It's new. Try to find the ambushing socket. 854 * Because we've rewritten the destination address, 855 * any hardware-generated hash is ignored. 856 */ 857 inp = in_pcblookup(&V_tcbinfo, ip->ip_src, 858 th->th_sport, next_hop->sin_addr, 859 next_hop->sin_port ? ntohs(next_hop->sin_port) : 860 th->th_dport, INPLOOKUP_WILDCARD | 861 INPLOOKUP_WLOCKPCB, m->m_pkthdr.rcvif); 862 } 863 } else 864 inp = in_pcblookup_mbuf(&V_tcbinfo, ip->ip_src, 865 th->th_sport, ip->ip_dst, th->th_dport, 866 INPLOOKUP_WILDCARD | INPLOOKUP_WLOCKPCB, 867 m->m_pkthdr.rcvif, m); 868 #endif /* INET */ 869 870 /* 871 * If the INPCB does not exist then all data in the incoming 872 * segment is discarded and an appropriate RST is sent back. 873 * XXX MRT Send RST using which routing table? 874 */ 875 if (inp == NULL) { 876 /* 877 * Log communication attempts to ports that are not 878 * in use. 879 */ 880 if ((tcp_log_in_vain == 1 && (thflags & TH_SYN)) || 881 tcp_log_in_vain == 2) { 882 if ((s = tcp_log_vain(NULL, th, (void *)ip, ip6))) 883 log(LOG_INFO, "%s; %s: Connection attempt " 884 "to closed port\n", s, __func__); 885 } 886 /* 887 * When blackholing do not respond with a RST but 888 * completely ignore the segment and drop it. 889 */ 890 if ((V_blackhole == 1 && (thflags & TH_SYN)) || 891 V_blackhole == 2) 892 goto dropunlock; 893 894 rstreason = BANDLIM_RST_CLOSEDPORT; 895 goto dropwithreset; 896 } 897 INP_WLOCK_ASSERT(inp); 898 /* 899 * While waiting for inp lock during the lookup, another thread 900 * can have dropped the inpcb, in which case we need to loop back 901 * and try to find a new inpcb to deliver to. 902 */ 903 if (inp->inp_flags & INP_DROPPED) { 904 INP_WUNLOCK(inp); 905 inp = NULL; 906 goto findpcb; 907 } 908 if ((inp->inp_flowtype == M_HASHTYPE_NONE) && 909 (M_HASHTYPE_GET(m) != M_HASHTYPE_NONE) && 910 ((inp->inp_socket == NULL) || 911 (inp->inp_socket->so_options & SO_ACCEPTCONN) == 0)) { 912 inp->inp_flowid = m->m_pkthdr.flowid; 913 inp->inp_flowtype = M_HASHTYPE_GET(m); 914 } 915 #if defined(IPSEC) || defined(IPSEC_SUPPORT) 916 #ifdef INET6 917 if (isipv6 && IPSEC_ENABLED(ipv6) && 918 IPSEC_CHECK_POLICY(ipv6, m, inp) != 0) { 919 goto dropunlock; 920 } 921 #ifdef INET 922 else 923 #endif 924 #endif /* INET6 */ 925 #ifdef INET 926 if (IPSEC_ENABLED(ipv4) && 927 IPSEC_CHECK_POLICY(ipv4, m, inp) != 0) { 928 goto dropunlock; 929 } 930 #endif /* INET */ 931 #endif /* IPSEC */ 932 933 /* 934 * Check the minimum TTL for socket. 935 */ 936 if (inp->inp_ip_minttl != 0) { 937 #ifdef INET6 938 if (isipv6) { 939 if (inp->inp_ip_minttl > ip6->ip6_hlim) 940 goto dropunlock; 941 } else 942 #endif 943 if (inp->inp_ip_minttl > ip->ip_ttl) 944 goto dropunlock; 945 } 946 947 /* 948 * A previous connection in TIMEWAIT state is supposed to catch stray 949 * or duplicate segments arriving late. If this segment was a 950 * legitimate new connection attempt, the old INPCB gets removed and 951 * we can try again to find a listening socket. 952 * 953 * At this point, due to earlier optimism, we may hold only an inpcb 954 * lock, and not the inpcbinfo write lock. If so, we need to try to 955 * acquire it, or if that fails, acquire a reference on the inpcb, 956 * drop all locks, acquire a global write lock, and then re-acquire 957 * the inpcb lock. We may at that point discover that another thread 958 * has tried to free the inpcb, in which case we need to loop back 959 * and try to find a new inpcb to deliver to. 960 * 961 * XXXRW: It may be time to rethink timewait locking. 962 */ 963 relocked: 964 if (inp->inp_flags & INP_TIMEWAIT) { 965 if (ti_locked == TI_UNLOCKED) { 966 if (INP_INFO_TRY_RLOCK(&V_tcbinfo) == 0) { 967 in_pcbref(inp); 968 INP_WUNLOCK(inp); 969 INP_INFO_RLOCK(&V_tcbinfo); 970 ti_locked = TI_RLOCKED; 971 INP_WLOCK(inp); 972 if (in_pcbrele_wlocked(inp)) { 973 inp = NULL; 974 goto findpcb; 975 } else if (inp->inp_flags & INP_DROPPED) { 976 INP_WUNLOCK(inp); 977 inp = NULL; 978 goto findpcb; 979 } 980 } else 981 ti_locked = TI_RLOCKED; 982 } 983 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 984 985 if (thflags & TH_SYN) 986 tcp_dooptions(&to, optp, optlen, TO_SYN); 987 /* 988 * NB: tcp_twcheck unlocks the INP and frees the mbuf. 989 */ 990 if (tcp_twcheck(inp, &to, th, m, tlen)) 991 goto findpcb; 992 INP_INFO_RUNLOCK(&V_tcbinfo); 993 return (IPPROTO_DONE); 994 } 995 /* 996 * The TCPCB may no longer exist if the connection is winding 997 * down or it is in the CLOSED state. Either way we drop the 998 * segment and send an appropriate response. 999 */ 1000 tp = intotcpcb(inp); 1001 if (tp == NULL || tp->t_state == TCPS_CLOSED) { 1002 rstreason = BANDLIM_RST_CLOSEDPORT; 1003 goto dropwithreset; 1004 } 1005 1006 #ifdef TCP_OFFLOAD 1007 if (tp->t_flags & TF_TOE) { 1008 tcp_offload_input(tp, m); 1009 m = NULL; /* consumed by the TOE driver */ 1010 goto dropunlock; 1011 } 1012 #endif 1013 1014 /* 1015 * We've identified a valid inpcb, but it could be that we need an 1016 * inpcbinfo write lock but don't hold it. In this case, attempt to 1017 * acquire using the same strategy as the TIMEWAIT case above. If we 1018 * relock, we have to jump back to 'relocked' as the connection might 1019 * now be in TIMEWAIT. 1020 */ 1021 #ifdef INVARIANTS 1022 if ((thflags & (TH_FIN | TH_RST)) != 0) 1023 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 1024 #endif 1025 if (!((tp->t_state == TCPS_ESTABLISHED && (thflags & TH_SYN) == 0) || 1026 (tp->t_state == TCPS_LISTEN && (thflags & TH_SYN) && 1027 !IS_FASTOPEN(tp->t_flags)))) { 1028 if (ti_locked == TI_UNLOCKED) { 1029 if (INP_INFO_TRY_RLOCK(&V_tcbinfo) == 0) { 1030 in_pcbref(inp); 1031 INP_WUNLOCK(inp); 1032 INP_INFO_RLOCK(&V_tcbinfo); 1033 ti_locked = TI_RLOCKED; 1034 INP_WLOCK(inp); 1035 if (in_pcbrele_wlocked(inp)) { 1036 inp = NULL; 1037 goto findpcb; 1038 } else if (inp->inp_flags & INP_DROPPED) { 1039 INP_WUNLOCK(inp); 1040 inp = NULL; 1041 goto findpcb; 1042 } 1043 goto relocked; 1044 } else 1045 ti_locked = TI_RLOCKED; 1046 } 1047 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 1048 } 1049 1050 #ifdef MAC 1051 INP_WLOCK_ASSERT(inp); 1052 if (mac_inpcb_check_deliver(inp, m)) 1053 goto dropunlock; 1054 #endif 1055 so = inp->inp_socket; 1056 KASSERT(so != NULL, ("%s: so == NULL", __func__)); 1057 #ifdef TCPDEBUG 1058 if (so->so_options & SO_DEBUG) { 1059 ostate = tp->t_state; 1060 #ifdef INET6 1061 if (isipv6) { 1062 bcopy((char *)ip6, (char *)tcp_saveipgen, sizeof(*ip6)); 1063 } else 1064 #endif 1065 bcopy((char *)ip, (char *)tcp_saveipgen, sizeof(*ip)); 1066 tcp_savetcp = *th; 1067 } 1068 #endif /* TCPDEBUG */ 1069 /* 1070 * When the socket is accepting connections (the INPCB is in LISTEN 1071 * state) we look into the SYN cache if this is a new connection 1072 * attempt or the completion of a previous one. 1073 */ 1074 KASSERT(tp->t_state == TCPS_LISTEN || !(so->so_options & SO_ACCEPTCONN), 1075 ("%s: so accepting but tp %p not listening", __func__, tp)); 1076 if (tp->t_state == TCPS_LISTEN && (so->so_options & SO_ACCEPTCONN)) { 1077 struct in_conninfo inc; 1078 1079 bzero(&inc, sizeof(inc)); 1080 #ifdef INET6 1081 if (isipv6) { 1082 inc.inc_flags |= INC_ISIPV6; 1083 inc.inc6_faddr = ip6->ip6_src; 1084 inc.inc6_laddr = ip6->ip6_dst; 1085 } else 1086 #endif 1087 { 1088 inc.inc_faddr = ip->ip_src; 1089 inc.inc_laddr = ip->ip_dst; 1090 } 1091 inc.inc_fport = th->th_sport; 1092 inc.inc_lport = th->th_dport; 1093 inc.inc_fibnum = so->so_fibnum; 1094 1095 /* 1096 * Check for an existing connection attempt in syncache if 1097 * the flag is only ACK. A successful lookup creates a new 1098 * socket appended to the listen queue in SYN_RECEIVED state. 1099 */ 1100 if ((thflags & (TH_RST|TH_ACK|TH_SYN)) == TH_ACK) { 1101 1102 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 1103 /* 1104 * Parse the TCP options here because 1105 * syncookies need access to the reflected 1106 * timestamp. 1107 */ 1108 tcp_dooptions(&to, optp, optlen, 0); 1109 /* 1110 * NB: syncache_expand() doesn't unlock 1111 * inp and tcpinfo locks. 1112 */ 1113 rstreason = syncache_expand(&inc, &to, th, &so, m); 1114 if (rstreason < 0) { 1115 /* 1116 * A failing TCP MD5 signature comparison 1117 * must result in the segment being dropped 1118 * and must not produce any response back 1119 * to the sender. 1120 */ 1121 goto dropunlock; 1122 } else if (rstreason == 0) { 1123 /* 1124 * No syncache entry or ACK was not 1125 * for our SYN/ACK. Send a RST. 1126 * NB: syncache did its own logging 1127 * of the failure cause. 1128 */ 1129 rstreason = BANDLIM_RST_OPENPORT; 1130 goto dropwithreset; 1131 } 1132 #ifdef TCP_RFC7413 1133 tfo_socket_result: 1134 #endif 1135 if (so == NULL) { 1136 /* 1137 * We completed the 3-way handshake 1138 * but could not allocate a socket 1139 * either due to memory shortage, 1140 * listen queue length limits or 1141 * global socket limits. Send RST 1142 * or wait and have the remote end 1143 * retransmit the ACK for another 1144 * try. 1145 */ 1146 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1147 log(LOG_DEBUG, "%s; %s: Listen socket: " 1148 "Socket allocation failed due to " 1149 "limits or memory shortage, %s\n", 1150 s, __func__, 1151 V_tcp_sc_rst_sock_fail ? 1152 "sending RST" : "try again"); 1153 if (V_tcp_sc_rst_sock_fail) { 1154 rstreason = BANDLIM_UNLIMITED; 1155 goto dropwithreset; 1156 } else 1157 goto dropunlock; 1158 } 1159 /* 1160 * Socket is created in state SYN_RECEIVED. 1161 * Unlock the listen socket, lock the newly 1162 * created socket and update the tp variable. 1163 */ 1164 INP_WUNLOCK(inp); /* listen socket */ 1165 inp = sotoinpcb(so); 1166 /* 1167 * New connection inpcb is already locked by 1168 * syncache_expand(). 1169 */ 1170 INP_WLOCK_ASSERT(inp); 1171 tp = intotcpcb(inp); 1172 KASSERT(tp->t_state == TCPS_SYN_RECEIVED, 1173 ("%s: ", __func__)); 1174 /* 1175 * Process the segment and the data it 1176 * contains. tcp_do_segment() consumes 1177 * the mbuf chain and unlocks the inpcb. 1178 */ 1179 tp->t_fb->tfb_tcp_do_segment(m, th, so, tp, drop_hdrlen, tlen, 1180 iptos, ti_locked); 1181 INP_INFO_UNLOCK_ASSERT(&V_tcbinfo); 1182 return (IPPROTO_DONE); 1183 } 1184 /* 1185 * Segment flag validation for new connection attempts: 1186 * 1187 * Our (SYN|ACK) response was rejected. 1188 * Check with syncache and remove entry to prevent 1189 * retransmits. 1190 * 1191 * NB: syncache_chkrst does its own logging of failure 1192 * causes. 1193 */ 1194 if (thflags & TH_RST) { 1195 syncache_chkrst(&inc, th); 1196 goto dropunlock; 1197 } 1198 /* 1199 * We can't do anything without SYN. 1200 */ 1201 if ((thflags & TH_SYN) == 0) { 1202 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1203 log(LOG_DEBUG, "%s; %s: Listen socket: " 1204 "SYN is missing, segment ignored\n", 1205 s, __func__); 1206 TCPSTAT_INC(tcps_badsyn); 1207 goto dropunlock; 1208 } 1209 /* 1210 * (SYN|ACK) is bogus on a listen socket. 1211 */ 1212 if (thflags & TH_ACK) { 1213 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1214 log(LOG_DEBUG, "%s; %s: Listen socket: " 1215 "SYN|ACK invalid, segment rejected\n", 1216 s, __func__); 1217 syncache_badack(&inc); /* XXX: Not needed! */ 1218 TCPSTAT_INC(tcps_badsyn); 1219 rstreason = BANDLIM_RST_OPENPORT; 1220 goto dropwithreset; 1221 } 1222 /* 1223 * If the drop_synfin option is enabled, drop all 1224 * segments with both the SYN and FIN bits set. 1225 * This prevents e.g. nmap from identifying the 1226 * TCP/IP stack. 1227 * XXX: Poor reasoning. nmap has other methods 1228 * and is constantly refining its stack detection 1229 * strategies. 1230 * XXX: This is a violation of the TCP specification 1231 * and was used by RFC1644. 1232 */ 1233 if ((thflags & TH_FIN) && V_drop_synfin) { 1234 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1235 log(LOG_DEBUG, "%s; %s: Listen socket: " 1236 "SYN|FIN segment ignored (based on " 1237 "sysctl setting)\n", s, __func__); 1238 TCPSTAT_INC(tcps_badsyn); 1239 goto dropunlock; 1240 } 1241 /* 1242 * Segment's flags are (SYN) or (SYN|FIN). 1243 * 1244 * TH_PUSH, TH_URG, TH_ECE, TH_CWR are ignored 1245 * as they do not affect the state of the TCP FSM. 1246 * The data pointed to by TH_URG and th_urp is ignored. 1247 */ 1248 KASSERT((thflags & (TH_RST|TH_ACK)) == 0, 1249 ("%s: Listen socket: TH_RST or TH_ACK set", __func__)); 1250 KASSERT(thflags & (TH_SYN), 1251 ("%s: Listen socket: TH_SYN not set", __func__)); 1252 #ifdef INET6 1253 /* 1254 * If deprecated address is forbidden, 1255 * we do not accept SYN to deprecated interface 1256 * address to prevent any new inbound connection from 1257 * getting established. 1258 * When we do not accept SYN, we send a TCP RST, 1259 * with deprecated source address (instead of dropping 1260 * it). We compromise it as it is much better for peer 1261 * to send a RST, and RST will be the final packet 1262 * for the exchange. 1263 * 1264 * If we do not forbid deprecated addresses, we accept 1265 * the SYN packet. RFC2462 does not suggest dropping 1266 * SYN in this case. 1267 * If we decipher RFC2462 5.5.4, it says like this: 1268 * 1. use of deprecated addr with existing 1269 * communication is okay - "SHOULD continue to be 1270 * used" 1271 * 2. use of it with new communication: 1272 * (2a) "SHOULD NOT be used if alternate address 1273 * with sufficient scope is available" 1274 * (2b) nothing mentioned otherwise. 1275 * Here we fall into (2b) case as we have no choice in 1276 * our source address selection - we must obey the peer. 1277 * 1278 * The wording in RFC2462 is confusing, and there are 1279 * multiple description text for deprecated address 1280 * handling - worse, they are not exactly the same. 1281 * I believe 5.5.4 is the best one, so we follow 5.5.4. 1282 */ 1283 if (isipv6 && !V_ip6_use_deprecated) { 1284 struct in6_ifaddr *ia6; 1285 1286 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */); 1287 if (ia6 != NULL && 1288 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) { 1289 ifa_free(&ia6->ia_ifa); 1290 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1291 log(LOG_DEBUG, "%s; %s: Listen socket: " 1292 "Connection attempt to deprecated " 1293 "IPv6 address rejected\n", 1294 s, __func__); 1295 rstreason = BANDLIM_RST_OPENPORT; 1296 goto dropwithreset; 1297 } 1298 if (ia6) 1299 ifa_free(&ia6->ia_ifa); 1300 } 1301 #endif /* INET6 */ 1302 /* 1303 * Basic sanity checks on incoming SYN requests: 1304 * Don't respond if the destination is a link layer 1305 * broadcast according to RFC1122 4.2.3.10, p. 104. 1306 * If it is from this socket it must be forged. 1307 * Don't respond if the source or destination is a 1308 * global or subnet broad- or multicast address. 1309 * Note that it is quite possible to receive unicast 1310 * link-layer packets with a broadcast IP address. Use 1311 * in_broadcast() to find them. 1312 */ 1313 if (m->m_flags & (M_BCAST|M_MCAST)) { 1314 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1315 log(LOG_DEBUG, "%s; %s: Listen socket: " 1316 "Connection attempt from broad- or multicast " 1317 "link layer address ignored\n", s, __func__); 1318 goto dropunlock; 1319 } 1320 #ifdef INET6 1321 if (isipv6) { 1322 if (th->th_dport == th->th_sport && 1323 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &ip6->ip6_src)) { 1324 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1325 log(LOG_DEBUG, "%s; %s: Listen socket: " 1326 "Connection attempt to/from self " 1327 "ignored\n", s, __func__); 1328 goto dropunlock; 1329 } 1330 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 1331 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) { 1332 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1333 log(LOG_DEBUG, "%s; %s: Listen socket: " 1334 "Connection attempt from/to multicast " 1335 "address ignored\n", s, __func__); 1336 goto dropunlock; 1337 } 1338 } 1339 #endif 1340 #if defined(INET) && defined(INET6) 1341 else 1342 #endif 1343 #ifdef INET 1344 { 1345 if (th->th_dport == th->th_sport && 1346 ip->ip_dst.s_addr == ip->ip_src.s_addr) { 1347 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1348 log(LOG_DEBUG, "%s; %s: Listen socket: " 1349 "Connection attempt from/to self " 1350 "ignored\n", s, __func__); 1351 goto dropunlock; 1352 } 1353 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 1354 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 1355 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || 1356 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) { 1357 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1358 log(LOG_DEBUG, "%s; %s: Listen socket: " 1359 "Connection attempt from/to broad- " 1360 "or multicast address ignored\n", 1361 s, __func__); 1362 goto dropunlock; 1363 } 1364 } 1365 #endif 1366 /* 1367 * SYN appears to be valid. Create compressed TCP state 1368 * for syncache. 1369 */ 1370 #ifdef TCPDEBUG 1371 if (so->so_options & SO_DEBUG) 1372 tcp_trace(TA_INPUT, ostate, tp, 1373 (void *)tcp_saveipgen, &tcp_savetcp, 0); 1374 #endif 1375 TCP_PROBE3(debug__input, tp, th, m); 1376 tcp_dooptions(&to, optp, optlen, TO_SYN); 1377 #ifdef TCP_RFC7413 1378 if (syncache_add(&inc, &to, th, inp, &so, m, NULL, NULL)) 1379 goto tfo_socket_result; 1380 #else 1381 syncache_add(&inc, &to, th, inp, &so, m, NULL, NULL); 1382 #endif 1383 /* 1384 * Entry added to syncache and mbuf consumed. 1385 * Only the listen socket is unlocked by syncache_add(). 1386 */ 1387 if (ti_locked == TI_RLOCKED) { 1388 INP_INFO_RUNLOCK(&V_tcbinfo); 1389 ti_locked = TI_UNLOCKED; 1390 } 1391 INP_INFO_UNLOCK_ASSERT(&V_tcbinfo); 1392 return (IPPROTO_DONE); 1393 } else if (tp->t_state == TCPS_LISTEN) { 1394 /* 1395 * When a listen socket is torn down the SO_ACCEPTCONN 1396 * flag is removed first while connections are drained 1397 * from the accept queue in a unlock/lock cycle of the 1398 * ACCEPT_LOCK, opening a race condition allowing a SYN 1399 * attempt go through unhandled. 1400 */ 1401 goto dropunlock; 1402 } 1403 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 1404 if (tp->t_flags & TF_SIGNATURE) { 1405 tcp_dooptions(&to, optp, optlen, thflags); 1406 if ((to.to_flags & TOF_SIGNATURE) == 0) { 1407 TCPSTAT_INC(tcps_sig_err_nosigopt); 1408 goto dropunlock; 1409 } 1410 if (!TCPMD5_ENABLED() || 1411 TCPMD5_INPUT(m, th, to.to_signature) != 0) 1412 goto dropunlock; 1413 } 1414 #endif 1415 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1416 1417 /* 1418 * Segment belongs to a connection in SYN_SENT, ESTABLISHED or later 1419 * state. tcp_do_segment() always consumes the mbuf chain, unlocks 1420 * the inpcb, and unlocks pcbinfo. 1421 */ 1422 tp->t_fb->tfb_tcp_do_segment(m, th, so, tp, drop_hdrlen, tlen, iptos, ti_locked); 1423 INP_INFO_UNLOCK_ASSERT(&V_tcbinfo); 1424 return (IPPROTO_DONE); 1425 1426 dropwithreset: 1427 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1428 1429 if (ti_locked == TI_RLOCKED) { 1430 INP_INFO_RUNLOCK(&V_tcbinfo); 1431 ti_locked = TI_UNLOCKED; 1432 } 1433 #ifdef INVARIANTS 1434 else { 1435 KASSERT(ti_locked == TI_UNLOCKED, ("%s: dropwithreset " 1436 "ti_locked: %d", __func__, ti_locked)); 1437 INP_INFO_UNLOCK_ASSERT(&V_tcbinfo); 1438 } 1439 #endif 1440 1441 if (inp != NULL) { 1442 tcp_dropwithreset(m, th, tp, tlen, rstreason); 1443 INP_WUNLOCK(inp); 1444 } else 1445 tcp_dropwithreset(m, th, NULL, tlen, rstreason); 1446 m = NULL; /* mbuf chain got consumed. */ 1447 goto drop; 1448 1449 dropunlock: 1450 if (m != NULL) 1451 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1452 1453 if (ti_locked == TI_RLOCKED) { 1454 INP_INFO_RUNLOCK(&V_tcbinfo); 1455 ti_locked = TI_UNLOCKED; 1456 } 1457 #ifdef INVARIANTS 1458 else { 1459 KASSERT(ti_locked == TI_UNLOCKED, ("%s: dropunlock " 1460 "ti_locked: %d", __func__, ti_locked)); 1461 INP_INFO_UNLOCK_ASSERT(&V_tcbinfo); 1462 } 1463 #endif 1464 1465 if (inp != NULL) 1466 INP_WUNLOCK(inp); 1467 1468 drop: 1469 INP_INFO_UNLOCK_ASSERT(&V_tcbinfo); 1470 if (s != NULL) 1471 free(s, M_TCPLOG); 1472 if (m != NULL) 1473 m_freem(m); 1474 return (IPPROTO_DONE); 1475 } 1476 1477 /* 1478 * Automatic sizing of receive socket buffer. Often the send 1479 * buffer size is not optimally adjusted to the actual network 1480 * conditions at hand (delay bandwidth product). Setting the 1481 * buffer size too small limits throughput on links with high 1482 * bandwidth and high delay (eg. trans-continental/oceanic links). 1483 * 1484 * On the receive side the socket buffer memory is only rarely 1485 * used to any significant extent. This allows us to be much 1486 * more aggressive in scaling the receive socket buffer. For 1487 * the case that the buffer space is actually used to a large 1488 * extent and we run out of kernel memory we can simply drop 1489 * the new segments; TCP on the sender will just retransmit it 1490 * later. Setting the buffer size too big may only consume too 1491 * much kernel memory if the application doesn't read() from 1492 * the socket or packet loss or reordering makes use of the 1493 * reassembly queue. 1494 * 1495 * The criteria to step up the receive buffer one notch are: 1496 * 1. Application has not set receive buffer size with 1497 * SO_RCVBUF. Setting SO_RCVBUF clears SB_AUTOSIZE. 1498 * 2. the number of bytes received during the time it takes 1499 * one timestamp to be reflected back to us (the RTT); 1500 * 3. received bytes per RTT is within seven eighth of the 1501 * current socket buffer size; 1502 * 4. receive buffer size has not hit maximal automatic size; 1503 * 1504 * This algorithm does one step per RTT at most and only if 1505 * we receive a bulk stream w/o packet losses or reorderings. 1506 * Shrinking the buffer during idle times is not necessary as 1507 * it doesn't consume any memory when idle. 1508 * 1509 * TODO: Only step up if the application is actually serving 1510 * the buffer to better manage the socket buffer resources. 1511 */ 1512 int 1513 tcp_autorcvbuf(struct mbuf *m, struct tcphdr *th, struct socket *so, 1514 struct tcpcb *tp, int tlen) 1515 { 1516 int newsize = 0; 1517 1518 if (V_tcp_do_autorcvbuf && (so->so_rcv.sb_flags & SB_AUTOSIZE) && 1519 tp->t_srtt != 0 && tp->rfbuf_ts != 0 && 1520 TCP_TS_TO_TICKS(tcp_ts_getticks() - tp->rfbuf_ts) > 1521 (tp->t_srtt >> TCP_RTT_SHIFT)) { 1522 if (tp->rfbuf_cnt > (so->so_rcv.sb_hiwat / 8 * 7) && 1523 so->so_rcv.sb_hiwat < V_tcp_autorcvbuf_max) { 1524 newsize = min(so->so_rcv.sb_hiwat + 1525 V_tcp_autorcvbuf_inc, V_tcp_autorcvbuf_max); 1526 } 1527 TCP_PROBE6(receive__autoresize, NULL, tp, m, tp, th, newsize); 1528 1529 /* Start over with next RTT. */ 1530 tp->rfbuf_ts = 0; 1531 tp->rfbuf_cnt = 0; 1532 } else { 1533 tp->rfbuf_cnt += tlen; /* add up */ 1534 } 1535 1536 return (newsize); 1537 } 1538 1539 void 1540 tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so, 1541 struct tcpcb *tp, int drop_hdrlen, int tlen, uint8_t iptos, 1542 int ti_locked) 1543 { 1544 int thflags, acked, ourfinisacked, needoutput = 0, sack_changed; 1545 int rstreason, todrop, win; 1546 uint32_t tiwin; 1547 uint16_t nsegs; 1548 char *s; 1549 struct in_conninfo *inc; 1550 struct mbuf *mfree; 1551 struct tcpopt to; 1552 #ifdef TCP_RFC7413 1553 int tfo_syn; 1554 #endif 1555 1556 #ifdef TCPDEBUG 1557 /* 1558 * The size of tcp_saveipgen must be the size of the max ip header, 1559 * now IPv6. 1560 */ 1561 u_char tcp_saveipgen[IP6_HDR_LEN]; 1562 struct tcphdr tcp_savetcp; 1563 short ostate = 0; 1564 #endif 1565 thflags = th->th_flags; 1566 inc = &tp->t_inpcb->inp_inc; 1567 tp->sackhint.last_sack_ack = 0; 1568 sack_changed = 0; 1569 nsegs = max(1, m->m_pkthdr.lro_nsegs); 1570 1571 /* 1572 * If this is either a state-changing packet or current state isn't 1573 * established, we require a write lock on tcbinfo. Otherwise, we 1574 * allow the tcbinfo to be in either alocked or unlocked, as the 1575 * caller may have unnecessarily acquired a write lock due to a race. 1576 */ 1577 if ((thflags & (TH_SYN | TH_FIN | TH_RST)) != 0 || 1578 tp->t_state != TCPS_ESTABLISHED) { 1579 KASSERT(ti_locked == TI_RLOCKED, ("%s ti_locked %d for " 1580 "SYN/FIN/RST/!EST", __func__, ti_locked)); 1581 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 1582 } else { 1583 #ifdef INVARIANTS 1584 if (ti_locked == TI_RLOCKED) 1585 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 1586 else { 1587 KASSERT(ti_locked == TI_UNLOCKED, ("%s: EST " 1588 "ti_locked: %d", __func__, ti_locked)); 1589 INP_INFO_UNLOCK_ASSERT(&V_tcbinfo); 1590 } 1591 #endif 1592 } 1593 INP_WLOCK_ASSERT(tp->t_inpcb); 1594 KASSERT(tp->t_state > TCPS_LISTEN, ("%s: TCPS_LISTEN", 1595 __func__)); 1596 KASSERT(tp->t_state != TCPS_TIME_WAIT, ("%s: TCPS_TIME_WAIT", 1597 __func__)); 1598 1599 #ifdef TCPPCAP 1600 /* Save segment, if requested. */ 1601 tcp_pcap_add(th, m, &(tp->t_inpkts)); 1602 #endif 1603 1604 if ((thflags & TH_SYN) && (thflags & TH_FIN) && V_drop_synfin) { 1605 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1606 log(LOG_DEBUG, "%s; %s: " 1607 "SYN|FIN segment ignored (based on " 1608 "sysctl setting)\n", s, __func__); 1609 free(s, M_TCPLOG); 1610 } 1611 goto drop; 1612 } 1613 1614 /* 1615 * If a segment with the ACK-bit set arrives in the SYN-SENT state 1616 * check SEQ.ACK first. 1617 */ 1618 if ((tp->t_state == TCPS_SYN_SENT) && (thflags & TH_ACK) && 1619 (SEQ_LEQ(th->th_ack, tp->iss) || SEQ_GT(th->th_ack, tp->snd_max))) { 1620 rstreason = BANDLIM_UNLIMITED; 1621 goto dropwithreset; 1622 } 1623 1624 /* 1625 * Segment received on connection. 1626 * Reset idle time and keep-alive timer. 1627 * XXX: This should be done after segment 1628 * validation to ignore broken/spoofed segs. 1629 */ 1630 tp->t_rcvtime = ticks; 1631 1632 /* 1633 * Scale up the window into a 32-bit value. 1634 * For the SYN_SENT state the scale is zero. 1635 */ 1636 tiwin = th->th_win << tp->snd_scale; 1637 1638 /* 1639 * TCP ECN processing. 1640 */ 1641 if (tp->t_flags & TF_ECN_PERMIT) { 1642 if (thflags & TH_CWR) 1643 tp->t_flags &= ~TF_ECN_SND_ECE; 1644 switch (iptos & IPTOS_ECN_MASK) { 1645 case IPTOS_ECN_CE: 1646 tp->t_flags |= TF_ECN_SND_ECE; 1647 TCPSTAT_INC(tcps_ecn_ce); 1648 break; 1649 case IPTOS_ECN_ECT0: 1650 TCPSTAT_INC(tcps_ecn_ect0); 1651 break; 1652 case IPTOS_ECN_ECT1: 1653 TCPSTAT_INC(tcps_ecn_ect1); 1654 break; 1655 } 1656 1657 /* Process a packet differently from RFC3168. */ 1658 cc_ecnpkt_handler(tp, th, iptos); 1659 1660 /* Congestion experienced. */ 1661 if (thflags & TH_ECE) { 1662 cc_cong_signal(tp, th, CC_ECN); 1663 } 1664 } 1665 1666 /* 1667 * Parse options on any incoming segment. 1668 */ 1669 tcp_dooptions(&to, (u_char *)(th + 1), 1670 (th->th_off << 2) - sizeof(struct tcphdr), 1671 (thflags & TH_SYN) ? TO_SYN : 0); 1672 1673 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 1674 if ((tp->t_flags & TF_SIGNATURE) != 0 && 1675 (to.to_flags & TOF_SIGNATURE) == 0) { 1676 TCPSTAT_INC(tcps_sig_err_sigopt); 1677 /* XXX: should drop? */ 1678 } 1679 #endif 1680 /* 1681 * If echoed timestamp is later than the current time, 1682 * fall back to non RFC1323 RTT calculation. Normalize 1683 * timestamp if syncookies were used when this connection 1684 * was established. 1685 */ 1686 if ((to.to_flags & TOF_TS) && (to.to_tsecr != 0)) { 1687 to.to_tsecr -= tp->ts_offset; 1688 if (TSTMP_GT(to.to_tsecr, tcp_ts_getticks())) 1689 to.to_tsecr = 0; 1690 } 1691 /* 1692 * Process options only when we get SYN/ACK back. The SYN case 1693 * for incoming connections is handled in tcp_syncache. 1694 * According to RFC1323 the window field in a SYN (i.e., a <SYN> 1695 * or <SYN,ACK>) segment itself is never scaled. 1696 * XXX this is traditional behavior, may need to be cleaned up. 1697 */ 1698 if (tp->t_state == TCPS_SYN_SENT && (thflags & TH_SYN)) { 1699 if ((to.to_flags & TOF_SCALE) && 1700 (tp->t_flags & TF_REQ_SCALE)) { 1701 tp->t_flags |= TF_RCVD_SCALE; 1702 tp->snd_scale = to.to_wscale; 1703 } 1704 /* 1705 * Initial send window. It will be updated with 1706 * the next incoming segment to the scaled value. 1707 */ 1708 tp->snd_wnd = th->th_win; 1709 if (to.to_flags & TOF_TS) { 1710 tp->t_flags |= TF_RCVD_TSTMP; 1711 tp->ts_recent = to.to_tsval; 1712 tp->ts_recent_age = tcp_ts_getticks(); 1713 } 1714 if (to.to_flags & TOF_MSS) 1715 tcp_mss(tp, to.to_mss); 1716 if ((tp->t_flags & TF_SACK_PERMIT) && 1717 (to.to_flags & TOF_SACKPERM) == 0) 1718 tp->t_flags &= ~TF_SACK_PERMIT; 1719 } 1720 1721 /* 1722 * If timestamps were negotiated during SYN/ACK they should 1723 * appear on every segment during this session and vice versa. 1724 */ 1725 if ((tp->t_flags & TF_RCVD_TSTMP) && !(to.to_flags & TOF_TS)) { 1726 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1727 log(LOG_DEBUG, "%s; %s: Timestamp missing, " 1728 "no action\n", s, __func__); 1729 free(s, M_TCPLOG); 1730 } 1731 } 1732 if (!(tp->t_flags & TF_RCVD_TSTMP) && (to.to_flags & TOF_TS)) { 1733 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1734 log(LOG_DEBUG, "%s; %s: Timestamp not expected, " 1735 "no action\n", s, __func__); 1736 free(s, M_TCPLOG); 1737 } 1738 } 1739 1740 /* 1741 * Header prediction: check for the two common cases 1742 * of a uni-directional data xfer. If the packet has 1743 * no control flags, is in-sequence, the window didn't 1744 * change and we're not retransmitting, it's a 1745 * candidate. If the length is zero and the ack moved 1746 * forward, we're the sender side of the xfer. Just 1747 * free the data acked & wake any higher level process 1748 * that was blocked waiting for space. If the length 1749 * is non-zero and the ack didn't move, we're the 1750 * receiver side. If we're getting packets in-order 1751 * (the reassembly queue is empty), add the data to 1752 * the socket buffer and note that we need a delayed ack. 1753 * Make sure that the hidden state-flags are also off. 1754 * Since we check for TCPS_ESTABLISHED first, it can only 1755 * be TH_NEEDSYN. 1756 */ 1757 if (tp->t_state == TCPS_ESTABLISHED && 1758 th->th_seq == tp->rcv_nxt && 1759 (thflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK && 1760 tp->snd_nxt == tp->snd_max && 1761 tiwin && tiwin == tp->snd_wnd && 1762 ((tp->t_flags & (TF_NEEDSYN|TF_NEEDFIN)) == 0) && 1763 LIST_EMPTY(&tp->t_segq) && 1764 ((to.to_flags & TOF_TS) == 0 || 1765 TSTMP_GEQ(to.to_tsval, tp->ts_recent)) ) { 1766 1767 /* 1768 * If last ACK falls within this segment's sequence numbers, 1769 * record the timestamp. 1770 * NOTE that the test is modified according to the latest 1771 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 1772 */ 1773 if ((to.to_flags & TOF_TS) != 0 && 1774 SEQ_LEQ(th->th_seq, tp->last_ack_sent)) { 1775 tp->ts_recent_age = tcp_ts_getticks(); 1776 tp->ts_recent = to.to_tsval; 1777 } 1778 1779 if (tlen == 0) { 1780 if (SEQ_GT(th->th_ack, tp->snd_una) && 1781 SEQ_LEQ(th->th_ack, tp->snd_max) && 1782 !IN_RECOVERY(tp->t_flags) && 1783 (to.to_flags & TOF_SACK) == 0 && 1784 TAILQ_EMPTY(&tp->snd_holes)) { 1785 /* 1786 * This is a pure ack for outstanding data. 1787 */ 1788 if (ti_locked == TI_RLOCKED) 1789 INP_INFO_RUNLOCK(&V_tcbinfo); 1790 ti_locked = TI_UNLOCKED; 1791 1792 TCPSTAT_INC(tcps_predack); 1793 1794 /* 1795 * "bad retransmit" recovery. 1796 */ 1797 if (tp->t_rxtshift == 1 && 1798 tp->t_flags & TF_PREVVALID && 1799 (int)(ticks - tp->t_badrxtwin) < 0) { 1800 cc_cong_signal(tp, th, CC_RTO_ERR); 1801 } 1802 1803 /* 1804 * Recalculate the transmit timer / rtt. 1805 * 1806 * Some boxes send broken timestamp replies 1807 * during the SYN+ACK phase, ignore 1808 * timestamps of 0 or we could calculate a 1809 * huge RTT and blow up the retransmit timer. 1810 */ 1811 if ((to.to_flags & TOF_TS) != 0 && 1812 to.to_tsecr) { 1813 uint32_t t; 1814 1815 t = tcp_ts_getticks() - to.to_tsecr; 1816 if (!tp->t_rttlow || tp->t_rttlow > t) 1817 tp->t_rttlow = t; 1818 tcp_xmit_timer(tp, 1819 TCP_TS_TO_TICKS(t) + 1); 1820 } else if (tp->t_rtttime && 1821 SEQ_GT(th->th_ack, tp->t_rtseq)) { 1822 if (!tp->t_rttlow || 1823 tp->t_rttlow > ticks - tp->t_rtttime) 1824 tp->t_rttlow = ticks - tp->t_rtttime; 1825 tcp_xmit_timer(tp, 1826 ticks - tp->t_rtttime); 1827 } 1828 acked = BYTES_THIS_ACK(tp, th); 1829 1830 #ifdef TCP_HHOOK 1831 /* Run HHOOK_TCP_ESTABLISHED_IN helper hooks. */ 1832 hhook_run_tcp_est_in(tp, th, &to); 1833 #endif 1834 1835 TCPSTAT_ADD(tcps_rcvackpack, nsegs); 1836 TCPSTAT_ADD(tcps_rcvackbyte, acked); 1837 sbdrop(&so->so_snd, acked); 1838 if (SEQ_GT(tp->snd_una, tp->snd_recover) && 1839 SEQ_LEQ(th->th_ack, tp->snd_recover)) 1840 tp->snd_recover = th->th_ack - 1; 1841 1842 /* 1843 * Let the congestion control algorithm update 1844 * congestion control related information. This 1845 * typically means increasing the congestion 1846 * window. 1847 */ 1848 cc_ack_received(tp, th, nsegs, CC_ACK); 1849 1850 tp->snd_una = th->th_ack; 1851 /* 1852 * Pull snd_wl2 up to prevent seq wrap relative 1853 * to th_ack. 1854 */ 1855 tp->snd_wl2 = th->th_ack; 1856 tp->t_dupacks = 0; 1857 m_freem(m); 1858 1859 /* 1860 * If all outstanding data are acked, stop 1861 * retransmit timer, otherwise restart timer 1862 * using current (possibly backed-off) value. 1863 * If process is waiting for space, 1864 * wakeup/selwakeup/signal. If data 1865 * are ready to send, let tcp_output 1866 * decide between more output or persist. 1867 */ 1868 #ifdef TCPDEBUG 1869 if (so->so_options & SO_DEBUG) 1870 tcp_trace(TA_INPUT, ostate, tp, 1871 (void *)tcp_saveipgen, 1872 &tcp_savetcp, 0); 1873 #endif 1874 TCP_PROBE3(debug__input, tp, th, m); 1875 if (tp->snd_una == tp->snd_max) 1876 tcp_timer_activate(tp, TT_REXMT, 0); 1877 else if (!tcp_timer_active(tp, TT_PERSIST)) 1878 tcp_timer_activate(tp, TT_REXMT, 1879 tp->t_rxtcur); 1880 sowwakeup(so); 1881 if (sbavail(&so->so_snd)) 1882 (void) tp->t_fb->tfb_tcp_output(tp); 1883 goto check_delack; 1884 } 1885 } else if (th->th_ack == tp->snd_una && 1886 tlen <= sbspace(&so->so_rcv)) { 1887 int newsize = 0; /* automatic sockbuf scaling */ 1888 1889 /* 1890 * This is a pure, in-sequence data packet with 1891 * nothing on the reassembly queue and we have enough 1892 * buffer space to take it. 1893 */ 1894 if (ti_locked == TI_RLOCKED) 1895 INP_INFO_RUNLOCK(&V_tcbinfo); 1896 ti_locked = TI_UNLOCKED; 1897 1898 /* Clean receiver SACK report if present */ 1899 if ((tp->t_flags & TF_SACK_PERMIT) && tp->rcv_numsacks) 1900 tcp_clean_sackreport(tp); 1901 TCPSTAT_INC(tcps_preddat); 1902 tp->rcv_nxt += tlen; 1903 /* 1904 * Pull snd_wl1 up to prevent seq wrap relative to 1905 * th_seq. 1906 */ 1907 tp->snd_wl1 = th->th_seq; 1908 /* 1909 * Pull rcv_up up to prevent seq wrap relative to 1910 * rcv_nxt. 1911 */ 1912 tp->rcv_up = tp->rcv_nxt; 1913 TCPSTAT_ADD(tcps_rcvpack, nsegs); 1914 TCPSTAT_ADD(tcps_rcvbyte, tlen); 1915 #ifdef TCPDEBUG 1916 if (so->so_options & SO_DEBUG) 1917 tcp_trace(TA_INPUT, ostate, tp, 1918 (void *)tcp_saveipgen, &tcp_savetcp, 0); 1919 #endif 1920 TCP_PROBE3(debug__input, tp, th, m); 1921 1922 newsize = tcp_autorcvbuf(m, th, so, tp, tlen); 1923 1924 /* Add data to socket buffer. */ 1925 SOCKBUF_LOCK(&so->so_rcv); 1926 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 1927 m_freem(m); 1928 } else { 1929 /* 1930 * Set new socket buffer size. 1931 * Give up when limit is reached. 1932 */ 1933 if (newsize) 1934 if (!sbreserve_locked(&so->so_rcv, 1935 newsize, so, NULL)) 1936 so->so_rcv.sb_flags &= ~SB_AUTOSIZE; 1937 m_adj(m, drop_hdrlen); /* delayed header drop */ 1938 sbappendstream_locked(&so->so_rcv, m, 0); 1939 } 1940 /* NB: sorwakeup_locked() does an implicit unlock. */ 1941 sorwakeup_locked(so); 1942 if (DELAY_ACK(tp, tlen)) { 1943 tp->t_flags |= TF_DELACK; 1944 } else { 1945 tp->t_flags |= TF_ACKNOW; 1946 tp->t_fb->tfb_tcp_output(tp); 1947 } 1948 goto check_delack; 1949 } 1950 } 1951 1952 /* 1953 * Calculate amount of space in receive window, 1954 * and then do TCP input processing. 1955 * Receive window is amount of space in rcv queue, 1956 * but not less than advertised window. 1957 */ 1958 win = sbspace(&so->so_rcv); 1959 if (win < 0) 1960 win = 0; 1961 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 1962 1963 switch (tp->t_state) { 1964 1965 /* 1966 * If the state is SYN_RECEIVED: 1967 * if seg contains an ACK, but not for our SYN/ACK, send a RST. 1968 */ 1969 case TCPS_SYN_RECEIVED: 1970 if ((thflags & TH_ACK) && 1971 (SEQ_LEQ(th->th_ack, tp->snd_una) || 1972 SEQ_GT(th->th_ack, tp->snd_max))) { 1973 rstreason = BANDLIM_RST_OPENPORT; 1974 goto dropwithreset; 1975 } 1976 #ifdef TCP_RFC7413 1977 if (IS_FASTOPEN(tp->t_flags)) { 1978 /* 1979 * When a TFO connection is in SYN_RECEIVED, the 1980 * only valid packets are the initial SYN, a 1981 * retransmit/copy of the initial SYN (possibly with 1982 * a subset of the original data), a valid ACK, a 1983 * FIN, or a RST. 1984 */ 1985 if ((thflags & (TH_SYN|TH_ACK)) == (TH_SYN|TH_ACK)) { 1986 rstreason = BANDLIM_RST_OPENPORT; 1987 goto dropwithreset; 1988 } else if (thflags & TH_SYN) { 1989 /* non-initial SYN is ignored */ 1990 if ((tcp_timer_active(tp, TT_DELACK) || 1991 tcp_timer_active(tp, TT_REXMT))) 1992 goto drop; 1993 } else if (!(thflags & (TH_ACK|TH_FIN|TH_RST))) { 1994 goto drop; 1995 } 1996 } 1997 #endif 1998 break; 1999 2000 /* 2001 * If the state is SYN_SENT: 2002 * if seg contains a RST with valid ACK (SEQ.ACK has already 2003 * been verified), then drop the connection. 2004 * if seg contains a RST without an ACK, drop the seg. 2005 * if seg does not contain SYN, then drop the seg. 2006 * Otherwise this is an acceptable SYN segment 2007 * initialize tp->rcv_nxt and tp->irs 2008 * if seg contains ack then advance tp->snd_una 2009 * if seg contains an ECE and ECN support is enabled, the stream 2010 * is ECN capable. 2011 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 2012 * arrange for segment to be acked (eventually) 2013 * continue processing rest of data/controls, beginning with URG 2014 */ 2015 case TCPS_SYN_SENT: 2016 if ((thflags & (TH_ACK|TH_RST)) == (TH_ACK|TH_RST)) { 2017 TCP_PROBE5(connect__refused, NULL, tp, 2018 m, tp, th); 2019 tp = tcp_drop(tp, ECONNREFUSED); 2020 } 2021 if (thflags & TH_RST) 2022 goto drop; 2023 if (!(thflags & TH_SYN)) 2024 goto drop; 2025 2026 tp->irs = th->th_seq; 2027 tcp_rcvseqinit(tp); 2028 if (thflags & TH_ACK) { 2029 TCPSTAT_INC(tcps_connects); 2030 soisconnected(so); 2031 #ifdef MAC 2032 mac_socketpeer_set_from_mbuf(m, so); 2033 #endif 2034 /* Do window scaling on this connection? */ 2035 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2036 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2037 tp->rcv_scale = tp->request_r_scale; 2038 } 2039 tp->rcv_adv += min(tp->rcv_wnd, 2040 TCP_MAXWIN << tp->rcv_scale); 2041 tp->snd_una++; /* SYN is acked */ 2042 /* 2043 * If there's data, delay ACK; if there's also a FIN 2044 * ACKNOW will be turned on later. 2045 */ 2046 if (DELAY_ACK(tp, tlen) && tlen != 0) 2047 tcp_timer_activate(tp, TT_DELACK, 2048 tcp_delacktime); 2049 else 2050 tp->t_flags |= TF_ACKNOW; 2051 2052 if ((thflags & TH_ECE) && V_tcp_do_ecn) { 2053 tp->t_flags |= TF_ECN_PERMIT; 2054 TCPSTAT_INC(tcps_ecn_shs); 2055 } 2056 2057 /* 2058 * Received <SYN,ACK> in SYN_SENT[*] state. 2059 * Transitions: 2060 * SYN_SENT --> ESTABLISHED 2061 * SYN_SENT* --> FIN_WAIT_1 2062 */ 2063 tp->t_starttime = ticks; 2064 if (tp->t_flags & TF_NEEDFIN) { 2065 tcp_state_change(tp, TCPS_FIN_WAIT_1); 2066 tp->t_flags &= ~TF_NEEDFIN; 2067 thflags &= ~TH_SYN; 2068 } else { 2069 tcp_state_change(tp, TCPS_ESTABLISHED); 2070 TCP_PROBE5(connect__established, NULL, tp, 2071 m, tp, th); 2072 cc_conn_init(tp); 2073 tcp_timer_activate(tp, TT_KEEP, 2074 TP_KEEPIDLE(tp)); 2075 } 2076 } else { 2077 /* 2078 * Received initial SYN in SYN-SENT[*] state => 2079 * simultaneous open. 2080 * If it succeeds, connection is * half-synchronized. 2081 * Otherwise, do 3-way handshake: 2082 * SYN-SENT -> SYN-RECEIVED 2083 * SYN-SENT* -> SYN-RECEIVED* 2084 */ 2085 tp->t_flags |= (TF_ACKNOW | TF_NEEDSYN); 2086 tcp_timer_activate(tp, TT_REXMT, 0); 2087 tcp_state_change(tp, TCPS_SYN_RECEIVED); 2088 } 2089 2090 KASSERT(ti_locked == TI_RLOCKED, ("%s: trimthenstep6: " 2091 "ti_locked %d", __func__, ti_locked)); 2092 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 2093 INP_WLOCK_ASSERT(tp->t_inpcb); 2094 2095 /* 2096 * Advance th->th_seq to correspond to first data byte. 2097 * If data, trim to stay within window, 2098 * dropping FIN if necessary. 2099 */ 2100 th->th_seq++; 2101 if (tlen > tp->rcv_wnd) { 2102 todrop = tlen - tp->rcv_wnd; 2103 m_adj(m, -todrop); 2104 tlen = tp->rcv_wnd; 2105 thflags &= ~TH_FIN; 2106 TCPSTAT_INC(tcps_rcvpackafterwin); 2107 TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); 2108 } 2109 tp->snd_wl1 = th->th_seq - 1; 2110 tp->rcv_up = th->th_seq; 2111 /* 2112 * Client side of transaction: already sent SYN and data. 2113 * If the remote host used T/TCP to validate the SYN, 2114 * our data will be ACK'd; if so, enter normal data segment 2115 * processing in the middle of step 5, ack processing. 2116 * Otherwise, goto step 6. 2117 */ 2118 if (thflags & TH_ACK) 2119 goto process_ACK; 2120 2121 goto step6; 2122 2123 /* 2124 * If the state is LAST_ACK or CLOSING or TIME_WAIT: 2125 * do normal processing. 2126 * 2127 * NB: Leftover from RFC1644 T/TCP. Cases to be reused later. 2128 */ 2129 case TCPS_LAST_ACK: 2130 case TCPS_CLOSING: 2131 break; /* continue normal processing */ 2132 } 2133 2134 /* 2135 * States other than LISTEN or SYN_SENT. 2136 * First check the RST flag and sequence number since reset segments 2137 * are exempt from the timestamp and connection count tests. This 2138 * fixes a bug introduced by the Stevens, vol. 2, p. 960 bugfix 2139 * below which allowed reset segments in half the sequence space 2140 * to fall though and be processed (which gives forged reset 2141 * segments with a random sequence number a 50 percent chance of 2142 * killing a connection). 2143 * Then check timestamp, if present. 2144 * Then check the connection count, if present. 2145 * Then check that at least some bytes of segment are within 2146 * receive window. If segment begins before rcv_nxt, 2147 * drop leading data (and SYN); if nothing left, just ack. 2148 */ 2149 if (thflags & TH_RST) { 2150 /* 2151 * RFC5961 Section 3.2 2152 * 2153 * - RST drops connection only if SEG.SEQ == RCV.NXT. 2154 * - If RST is in window, we send challenge ACK. 2155 * 2156 * Note: to take into account delayed ACKs, we should 2157 * test against last_ack_sent instead of rcv_nxt. 2158 * Note 2: we handle special case of closed window, not 2159 * covered by the RFC. 2160 */ 2161 if ((SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 2162 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) || 2163 (tp->rcv_wnd == 0 && tp->last_ack_sent == th->th_seq)) { 2164 2165 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 2166 KASSERT(ti_locked == TI_RLOCKED, 2167 ("%s: TH_RST ti_locked %d, th %p tp %p", 2168 __func__, ti_locked, th, tp)); 2169 KASSERT(tp->t_state != TCPS_SYN_SENT, 2170 ("%s: TH_RST for TCPS_SYN_SENT th %p tp %p", 2171 __func__, th, tp)); 2172 2173 if (V_tcp_insecure_rst || 2174 tp->last_ack_sent == th->th_seq) { 2175 TCPSTAT_INC(tcps_drops); 2176 /* Drop the connection. */ 2177 switch (tp->t_state) { 2178 case TCPS_SYN_RECEIVED: 2179 so->so_error = ECONNREFUSED; 2180 goto close; 2181 case TCPS_ESTABLISHED: 2182 case TCPS_FIN_WAIT_1: 2183 case TCPS_FIN_WAIT_2: 2184 case TCPS_CLOSE_WAIT: 2185 case TCPS_CLOSING: 2186 case TCPS_LAST_ACK: 2187 so->so_error = ECONNRESET; 2188 close: 2189 /* FALLTHROUGH */ 2190 default: 2191 tp = tcp_close(tp); 2192 } 2193 } else { 2194 TCPSTAT_INC(tcps_badrst); 2195 /* Send challenge ACK. */ 2196 tcp_respond(tp, mtod(m, void *), th, m, 2197 tp->rcv_nxt, tp->snd_nxt, TH_ACK); 2198 tp->last_ack_sent = tp->rcv_nxt; 2199 m = NULL; 2200 } 2201 } 2202 goto drop; 2203 } 2204 2205 /* 2206 * RFC5961 Section 4.2 2207 * Send challenge ACK for any SYN in synchronized state. 2208 */ 2209 if ((thflags & TH_SYN) && tp->t_state != TCPS_SYN_SENT && 2210 tp->t_state != TCPS_SYN_RECEIVED) { 2211 KASSERT(ti_locked == TI_RLOCKED, 2212 ("tcp_do_segment: TH_SYN ti_locked %d", ti_locked)); 2213 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 2214 2215 TCPSTAT_INC(tcps_badsyn); 2216 if (V_tcp_insecure_syn && 2217 SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 2218 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) { 2219 tp = tcp_drop(tp, ECONNRESET); 2220 rstreason = BANDLIM_UNLIMITED; 2221 } else { 2222 /* Send challenge ACK. */ 2223 tcp_respond(tp, mtod(m, void *), th, m, tp->rcv_nxt, 2224 tp->snd_nxt, TH_ACK); 2225 tp->last_ack_sent = tp->rcv_nxt; 2226 m = NULL; 2227 } 2228 goto drop; 2229 } 2230 2231 /* 2232 * RFC 1323 PAWS: If we have a timestamp reply on this segment 2233 * and it's less than ts_recent, drop it. 2234 */ 2235 if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent && 2236 TSTMP_LT(to.to_tsval, tp->ts_recent)) { 2237 2238 /* Check to see if ts_recent is over 24 days old. */ 2239 if (tcp_ts_getticks() - tp->ts_recent_age > TCP_PAWS_IDLE) { 2240 /* 2241 * Invalidate ts_recent. If this segment updates 2242 * ts_recent, the age will be reset later and ts_recent 2243 * will get a valid value. If it does not, setting 2244 * ts_recent to zero will at least satisfy the 2245 * requirement that zero be placed in the timestamp 2246 * echo reply when ts_recent isn't valid. The 2247 * age isn't reset until we get a valid ts_recent 2248 * because we don't want out-of-order segments to be 2249 * dropped when ts_recent is old. 2250 */ 2251 tp->ts_recent = 0; 2252 } else { 2253 TCPSTAT_INC(tcps_rcvduppack); 2254 TCPSTAT_ADD(tcps_rcvdupbyte, tlen); 2255 TCPSTAT_INC(tcps_pawsdrop); 2256 if (tlen) 2257 goto dropafterack; 2258 goto drop; 2259 } 2260 } 2261 2262 /* 2263 * In the SYN-RECEIVED state, validate that the packet belongs to 2264 * this connection before trimming the data to fit the receive 2265 * window. Check the sequence number versus IRS since we know 2266 * the sequence numbers haven't wrapped. This is a partial fix 2267 * for the "LAND" DoS attack. 2268 */ 2269 if (tp->t_state == TCPS_SYN_RECEIVED && SEQ_LT(th->th_seq, tp->irs)) { 2270 rstreason = BANDLIM_RST_OPENPORT; 2271 goto dropwithreset; 2272 } 2273 2274 todrop = tp->rcv_nxt - th->th_seq; 2275 if (todrop > 0) { 2276 if (thflags & TH_SYN) { 2277 thflags &= ~TH_SYN; 2278 th->th_seq++; 2279 if (th->th_urp > 1) 2280 th->th_urp--; 2281 else 2282 thflags &= ~TH_URG; 2283 todrop--; 2284 } 2285 /* 2286 * Following if statement from Stevens, vol. 2, p. 960. 2287 */ 2288 if (todrop > tlen 2289 || (todrop == tlen && (thflags & TH_FIN) == 0)) { 2290 /* 2291 * Any valid FIN must be to the left of the window. 2292 * At this point the FIN must be a duplicate or out 2293 * of sequence; drop it. 2294 */ 2295 thflags &= ~TH_FIN; 2296 2297 /* 2298 * Send an ACK to resynchronize and drop any data. 2299 * But keep on processing for RST or ACK. 2300 */ 2301 tp->t_flags |= TF_ACKNOW; 2302 todrop = tlen; 2303 TCPSTAT_INC(tcps_rcvduppack); 2304 TCPSTAT_ADD(tcps_rcvdupbyte, todrop); 2305 } else { 2306 TCPSTAT_INC(tcps_rcvpartduppack); 2307 TCPSTAT_ADD(tcps_rcvpartdupbyte, todrop); 2308 } 2309 drop_hdrlen += todrop; /* drop from the top afterwards */ 2310 th->th_seq += todrop; 2311 tlen -= todrop; 2312 if (th->th_urp > todrop) 2313 th->th_urp -= todrop; 2314 else { 2315 thflags &= ~TH_URG; 2316 th->th_urp = 0; 2317 } 2318 } 2319 2320 /* 2321 * If new data are received on a connection after the 2322 * user processes are gone, then RST the other end. 2323 */ 2324 if ((so->so_state & SS_NOFDREF) && 2325 tp->t_state > TCPS_CLOSE_WAIT && tlen) { 2326 KASSERT(ti_locked == TI_RLOCKED, ("%s: SS_NOFDEREF && " 2327 "CLOSE_WAIT && tlen ti_locked %d", __func__, ti_locked)); 2328 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 2329 2330 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 2331 log(LOG_DEBUG, "%s; %s: %s: Received %d bytes of data " 2332 "after socket was closed, " 2333 "sending RST and removing tcpcb\n", 2334 s, __func__, tcpstates[tp->t_state], tlen); 2335 free(s, M_TCPLOG); 2336 } 2337 tp = tcp_close(tp); 2338 TCPSTAT_INC(tcps_rcvafterclose); 2339 rstreason = BANDLIM_UNLIMITED; 2340 goto dropwithreset; 2341 } 2342 2343 /* 2344 * If segment ends after window, drop trailing data 2345 * (and PUSH and FIN); if nothing left, just ACK. 2346 */ 2347 todrop = (th->th_seq + tlen) - (tp->rcv_nxt + tp->rcv_wnd); 2348 if (todrop > 0) { 2349 TCPSTAT_INC(tcps_rcvpackafterwin); 2350 if (todrop >= tlen) { 2351 TCPSTAT_ADD(tcps_rcvbyteafterwin, tlen); 2352 /* 2353 * If window is closed can only take segments at 2354 * window edge, and have to drop data and PUSH from 2355 * incoming segments. Continue processing, but 2356 * remember to ack. Otherwise, drop segment 2357 * and ack. 2358 */ 2359 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 2360 tp->t_flags |= TF_ACKNOW; 2361 TCPSTAT_INC(tcps_rcvwinprobe); 2362 } else 2363 goto dropafterack; 2364 } else 2365 TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); 2366 m_adj(m, -todrop); 2367 tlen -= todrop; 2368 thflags &= ~(TH_PUSH|TH_FIN); 2369 } 2370 2371 /* 2372 * If last ACK falls within this segment's sequence numbers, 2373 * record its timestamp. 2374 * NOTE: 2375 * 1) That the test incorporates suggestions from the latest 2376 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 2377 * 2) That updating only on newer timestamps interferes with 2378 * our earlier PAWS tests, so this check should be solely 2379 * predicated on the sequence space of this segment. 2380 * 3) That we modify the segment boundary check to be 2381 * Last.ACK.Sent <= SEG.SEQ + SEG.Len 2382 * instead of RFC1323's 2383 * Last.ACK.Sent < SEG.SEQ + SEG.Len, 2384 * This modified check allows us to overcome RFC1323's 2385 * limitations as described in Stevens TCP/IP Illustrated 2386 * Vol. 2 p.869. In such cases, we can still calculate the 2387 * RTT correctly when RCV.NXT == Last.ACK.Sent. 2388 */ 2389 if ((to.to_flags & TOF_TS) != 0 && 2390 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 2391 SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen + 2392 ((thflags & (TH_SYN|TH_FIN)) != 0))) { 2393 tp->ts_recent_age = tcp_ts_getticks(); 2394 tp->ts_recent = to.to_tsval; 2395 } 2396 2397 /* 2398 * If the ACK bit is off: if in SYN-RECEIVED state or SENDSYN 2399 * flag is on (half-synchronized state), then queue data for 2400 * later processing; else drop segment and return. 2401 */ 2402 if ((thflags & TH_ACK) == 0) { 2403 if (tp->t_state == TCPS_SYN_RECEIVED || 2404 (tp->t_flags & TF_NEEDSYN)) { 2405 #ifdef TCP_RFC7413 2406 if (tp->t_state == TCPS_SYN_RECEIVED && 2407 IS_FASTOPEN(tp->t_flags)) { 2408 tp->snd_wnd = tiwin; 2409 cc_conn_init(tp); 2410 } 2411 #endif 2412 goto step6; 2413 } else if (tp->t_flags & TF_ACKNOW) 2414 goto dropafterack; 2415 else 2416 goto drop; 2417 } 2418 2419 /* 2420 * Ack processing. 2421 */ 2422 switch (tp->t_state) { 2423 2424 /* 2425 * In SYN_RECEIVED state, the ack ACKs our SYN, so enter 2426 * ESTABLISHED state and continue processing. 2427 * The ACK was checked above. 2428 */ 2429 case TCPS_SYN_RECEIVED: 2430 2431 TCPSTAT_INC(tcps_connects); 2432 soisconnected(so); 2433 /* Do window scaling? */ 2434 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2435 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2436 tp->rcv_scale = tp->request_r_scale; 2437 tp->snd_wnd = tiwin; 2438 } 2439 /* 2440 * Make transitions: 2441 * SYN-RECEIVED -> ESTABLISHED 2442 * SYN-RECEIVED* -> FIN-WAIT-1 2443 */ 2444 tp->t_starttime = ticks; 2445 if (tp->t_flags & TF_NEEDFIN) { 2446 tcp_state_change(tp, TCPS_FIN_WAIT_1); 2447 tp->t_flags &= ~TF_NEEDFIN; 2448 } else { 2449 tcp_state_change(tp, TCPS_ESTABLISHED); 2450 TCP_PROBE5(accept__established, NULL, tp, 2451 m, tp, th); 2452 #ifdef TCP_RFC7413 2453 if (tp->t_tfo_pending) { 2454 tcp_fastopen_decrement_counter(tp->t_tfo_pending); 2455 tp->t_tfo_pending = NULL; 2456 2457 /* 2458 * Account for the ACK of our SYN prior to 2459 * regular ACK processing below. 2460 */ 2461 tp->snd_una++; 2462 } 2463 /* 2464 * TFO connections call cc_conn_init() during SYN 2465 * processing. Calling it again here for such 2466 * connections is not harmless as it would undo the 2467 * snd_cwnd reduction that occurs when a TFO SYN|ACK 2468 * is retransmitted. 2469 */ 2470 if (!IS_FASTOPEN(tp->t_flags)) 2471 #endif 2472 cc_conn_init(tp); 2473 tcp_timer_activate(tp, TT_KEEP, TP_KEEPIDLE(tp)); 2474 } 2475 /* 2476 * If segment contains data or ACK, will call tcp_reass() 2477 * later; if not, do so now to pass queued data to user. 2478 */ 2479 if (tlen == 0 && (thflags & TH_FIN) == 0) 2480 (void) tcp_reass(tp, (struct tcphdr *)0, 0, 2481 (struct mbuf *)0); 2482 tp->snd_wl1 = th->th_seq - 1; 2483 /* FALLTHROUGH */ 2484 2485 /* 2486 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 2487 * ACKs. If the ack is in the range 2488 * tp->snd_una < th->th_ack <= tp->snd_max 2489 * then advance tp->snd_una to th->th_ack and drop 2490 * data from the retransmission queue. If this ACK reflects 2491 * more up to date window information we update our window information. 2492 */ 2493 case TCPS_ESTABLISHED: 2494 case TCPS_FIN_WAIT_1: 2495 case TCPS_FIN_WAIT_2: 2496 case TCPS_CLOSE_WAIT: 2497 case TCPS_CLOSING: 2498 case TCPS_LAST_ACK: 2499 if (SEQ_GT(th->th_ack, tp->snd_max)) { 2500 TCPSTAT_INC(tcps_rcvacktoomuch); 2501 goto dropafterack; 2502 } 2503 if ((tp->t_flags & TF_SACK_PERMIT) && 2504 ((to.to_flags & TOF_SACK) || 2505 !TAILQ_EMPTY(&tp->snd_holes))) 2506 sack_changed = tcp_sack_doack(tp, &to, th->th_ack); 2507 else 2508 /* 2509 * Reset the value so that previous (valid) value 2510 * from the last ack with SACK doesn't get used. 2511 */ 2512 tp->sackhint.sacked_bytes = 0; 2513 2514 #ifdef TCP_HHOOK 2515 /* Run HHOOK_TCP_ESTABLISHED_IN helper hooks. */ 2516 hhook_run_tcp_est_in(tp, th, &to); 2517 #endif 2518 2519 if (SEQ_LEQ(th->th_ack, tp->snd_una)) { 2520 u_int maxseg; 2521 2522 maxseg = tcp_maxseg(tp); 2523 if (tlen == 0 && 2524 (tiwin == tp->snd_wnd || 2525 (tp->t_flags & TF_SACK_PERMIT))) { 2526 /* 2527 * If this is the first time we've seen a 2528 * FIN from the remote, this is not a 2529 * duplicate and it needs to be processed 2530 * normally. This happens during a 2531 * simultaneous close. 2532 */ 2533 if ((thflags & TH_FIN) && 2534 (TCPS_HAVERCVDFIN(tp->t_state) == 0)) { 2535 tp->t_dupacks = 0; 2536 break; 2537 } 2538 TCPSTAT_INC(tcps_rcvdupack); 2539 /* 2540 * If we have outstanding data (other than 2541 * a window probe), this is a completely 2542 * duplicate ack (ie, window info didn't 2543 * change and FIN isn't set), 2544 * the ack is the biggest we've 2545 * seen and we've seen exactly our rexmt 2546 * threshold of them, assume a packet 2547 * has been dropped and retransmit it. 2548 * Kludge snd_nxt & the congestion 2549 * window so we send only this one 2550 * packet. 2551 * 2552 * We know we're losing at the current 2553 * window size so do congestion avoidance 2554 * (set ssthresh to half the current window 2555 * and pull our congestion window back to 2556 * the new ssthresh). 2557 * 2558 * Dup acks mean that packets have left the 2559 * network (they're now cached at the receiver) 2560 * so bump cwnd by the amount in the receiver 2561 * to keep a constant cwnd packets in the 2562 * network. 2563 * 2564 * When using TCP ECN, notify the peer that 2565 * we reduced the cwnd. 2566 */ 2567 /* 2568 * Following 2 kinds of acks should not affect 2569 * dupack counting: 2570 * 1) Old acks 2571 * 2) Acks with SACK but without any new SACK 2572 * information in them. These could result from 2573 * any anomaly in the network like a switch 2574 * duplicating packets or a possible DoS attack. 2575 */ 2576 if (th->th_ack != tp->snd_una || 2577 ((tp->t_flags & TF_SACK_PERMIT) && 2578 !sack_changed)) 2579 break; 2580 else if (!tcp_timer_active(tp, TT_REXMT)) 2581 tp->t_dupacks = 0; 2582 else if (++tp->t_dupacks > tcprexmtthresh || 2583 IN_FASTRECOVERY(tp->t_flags)) { 2584 cc_ack_received(tp, th, nsegs, 2585 CC_DUPACK); 2586 if ((tp->t_flags & TF_SACK_PERMIT) && 2587 IN_FASTRECOVERY(tp->t_flags)) { 2588 int awnd; 2589 2590 /* 2591 * Compute the amount of data in flight first. 2592 * We can inject new data into the pipe iff 2593 * we have less than 1/2 the original window's 2594 * worth of data in flight. 2595 */ 2596 if (V_tcp_do_rfc6675_pipe) 2597 awnd = tcp_compute_pipe(tp); 2598 else 2599 awnd = (tp->snd_nxt - tp->snd_fack) + 2600 tp->sackhint.sack_bytes_rexmit; 2601 2602 if (awnd < tp->snd_ssthresh) { 2603 tp->snd_cwnd += maxseg; 2604 if (tp->snd_cwnd > tp->snd_ssthresh) 2605 tp->snd_cwnd = tp->snd_ssthresh; 2606 } 2607 } else 2608 tp->snd_cwnd += maxseg; 2609 (void) tp->t_fb->tfb_tcp_output(tp); 2610 goto drop; 2611 } else if (tp->t_dupacks == tcprexmtthresh) { 2612 tcp_seq onxt = tp->snd_nxt; 2613 2614 /* 2615 * If we're doing sack, check to 2616 * see if we're already in sack 2617 * recovery. If we're not doing sack, 2618 * check to see if we're in newreno 2619 * recovery. 2620 */ 2621 if (tp->t_flags & TF_SACK_PERMIT) { 2622 if (IN_FASTRECOVERY(tp->t_flags)) { 2623 tp->t_dupacks = 0; 2624 break; 2625 } 2626 } else { 2627 if (SEQ_LEQ(th->th_ack, 2628 tp->snd_recover)) { 2629 tp->t_dupacks = 0; 2630 break; 2631 } 2632 } 2633 /* Congestion signal before ack. */ 2634 cc_cong_signal(tp, th, CC_NDUPACK); 2635 cc_ack_received(tp, th, nsegs, 2636 CC_DUPACK); 2637 tcp_timer_activate(tp, TT_REXMT, 0); 2638 tp->t_rtttime = 0; 2639 if (tp->t_flags & TF_SACK_PERMIT) { 2640 TCPSTAT_INC( 2641 tcps_sack_recovery_episode); 2642 tp->sack_newdata = tp->snd_nxt; 2643 tp->snd_cwnd = maxseg; 2644 (void) tp->t_fb->tfb_tcp_output(tp); 2645 goto drop; 2646 } 2647 tp->snd_nxt = th->th_ack; 2648 tp->snd_cwnd = maxseg; 2649 (void) tp->t_fb->tfb_tcp_output(tp); 2650 KASSERT(tp->snd_limited <= 2, 2651 ("%s: tp->snd_limited too big", 2652 __func__)); 2653 tp->snd_cwnd = tp->snd_ssthresh + 2654 maxseg * 2655 (tp->t_dupacks - tp->snd_limited); 2656 if (SEQ_GT(onxt, tp->snd_nxt)) 2657 tp->snd_nxt = onxt; 2658 goto drop; 2659 } else if (V_tcp_do_rfc3042) { 2660 /* 2661 * Process first and second duplicate 2662 * ACKs. Each indicates a segment 2663 * leaving the network, creating room 2664 * for more. Make sure we can send a 2665 * packet on reception of each duplicate 2666 * ACK by increasing snd_cwnd by one 2667 * segment. Restore the original 2668 * snd_cwnd after packet transmission. 2669 */ 2670 cc_ack_received(tp, th, nsegs, 2671 CC_DUPACK); 2672 uint32_t oldcwnd = tp->snd_cwnd; 2673 tcp_seq oldsndmax = tp->snd_max; 2674 u_int sent; 2675 int avail; 2676 2677 KASSERT(tp->t_dupacks == 1 || 2678 tp->t_dupacks == 2, 2679 ("%s: dupacks not 1 or 2", 2680 __func__)); 2681 if (tp->t_dupacks == 1) 2682 tp->snd_limited = 0; 2683 tp->snd_cwnd = 2684 (tp->snd_nxt - tp->snd_una) + 2685 (tp->t_dupacks - tp->snd_limited) * 2686 maxseg; 2687 /* 2688 * Only call tcp_output when there 2689 * is new data available to be sent. 2690 * Otherwise we would send pure ACKs. 2691 */ 2692 SOCKBUF_LOCK(&so->so_snd); 2693 avail = sbavail(&so->so_snd) - 2694 (tp->snd_nxt - tp->snd_una); 2695 SOCKBUF_UNLOCK(&so->so_snd); 2696 if (avail > 0) 2697 (void) tp->t_fb->tfb_tcp_output(tp); 2698 sent = tp->snd_max - oldsndmax; 2699 if (sent > maxseg) { 2700 KASSERT((tp->t_dupacks == 2 && 2701 tp->snd_limited == 0) || 2702 (sent == maxseg + 1 && 2703 tp->t_flags & TF_SENTFIN), 2704 ("%s: sent too much", 2705 __func__)); 2706 tp->snd_limited = 2; 2707 } else if (sent > 0) 2708 ++tp->snd_limited; 2709 tp->snd_cwnd = oldcwnd; 2710 goto drop; 2711 } 2712 } 2713 break; 2714 } else { 2715 /* 2716 * This ack is advancing the left edge, reset the 2717 * counter. 2718 */ 2719 tp->t_dupacks = 0; 2720 /* 2721 * If this ack also has new SACK info, increment the 2722 * counter as per rfc6675. 2723 */ 2724 if ((tp->t_flags & TF_SACK_PERMIT) && sack_changed) 2725 tp->t_dupacks++; 2726 } 2727 2728 KASSERT(SEQ_GT(th->th_ack, tp->snd_una), 2729 ("%s: th_ack <= snd_una", __func__)); 2730 2731 /* 2732 * If the congestion window was inflated to account 2733 * for the other side's cached packets, retract it. 2734 */ 2735 if (IN_FASTRECOVERY(tp->t_flags)) { 2736 if (SEQ_LT(th->th_ack, tp->snd_recover)) { 2737 if (tp->t_flags & TF_SACK_PERMIT) 2738 tcp_sack_partialack(tp, th); 2739 else 2740 tcp_newreno_partial_ack(tp, th); 2741 } else 2742 cc_post_recovery(tp, th); 2743 } 2744 /* 2745 * If we reach this point, ACK is not a duplicate, 2746 * i.e., it ACKs something we sent. 2747 */ 2748 if (tp->t_flags & TF_NEEDSYN) { 2749 /* 2750 * T/TCP: Connection was half-synchronized, and our 2751 * SYN has been ACK'd (so connection is now fully 2752 * synchronized). Go to non-starred state, 2753 * increment snd_una for ACK of SYN, and check if 2754 * we can do window scaling. 2755 */ 2756 tp->t_flags &= ~TF_NEEDSYN; 2757 tp->snd_una++; 2758 /* Do window scaling? */ 2759 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2760 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2761 tp->rcv_scale = tp->request_r_scale; 2762 /* Send window already scaled. */ 2763 } 2764 } 2765 2766 process_ACK: 2767 INP_WLOCK_ASSERT(tp->t_inpcb); 2768 2769 acked = BYTES_THIS_ACK(tp, th); 2770 KASSERT(acked >= 0, ("%s: acked unexepectedly negative " 2771 "(tp->snd_una=%u, th->th_ack=%u, tp=%p, m=%p)", __func__, 2772 tp->snd_una, th->th_ack, tp, m)); 2773 TCPSTAT_ADD(tcps_rcvackpack, nsegs); 2774 TCPSTAT_ADD(tcps_rcvackbyte, acked); 2775 2776 /* 2777 * If we just performed our first retransmit, and the ACK 2778 * arrives within our recovery window, then it was a mistake 2779 * to do the retransmit in the first place. Recover our 2780 * original cwnd and ssthresh, and proceed to transmit where 2781 * we left off. 2782 */ 2783 if (tp->t_rxtshift == 1 && tp->t_flags & TF_PREVVALID && 2784 (int)(ticks - tp->t_badrxtwin) < 0) 2785 cc_cong_signal(tp, th, CC_RTO_ERR); 2786 2787 /* 2788 * If we have a timestamp reply, update smoothed 2789 * round trip time. If no timestamp is present but 2790 * transmit timer is running and timed sequence 2791 * number was acked, update smoothed round trip time. 2792 * Since we now have an rtt measurement, cancel the 2793 * timer backoff (cf., Phil Karn's retransmit alg.). 2794 * Recompute the initial retransmit timer. 2795 * 2796 * Some boxes send broken timestamp replies 2797 * during the SYN+ACK phase, ignore 2798 * timestamps of 0 or we could calculate a 2799 * huge RTT and blow up the retransmit timer. 2800 */ 2801 if ((to.to_flags & TOF_TS) != 0 && to.to_tsecr) { 2802 uint32_t t; 2803 2804 t = tcp_ts_getticks() - to.to_tsecr; 2805 if (!tp->t_rttlow || tp->t_rttlow > t) 2806 tp->t_rttlow = t; 2807 tcp_xmit_timer(tp, TCP_TS_TO_TICKS(t) + 1); 2808 } else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) { 2809 if (!tp->t_rttlow || tp->t_rttlow > ticks - tp->t_rtttime) 2810 tp->t_rttlow = ticks - tp->t_rtttime; 2811 tcp_xmit_timer(tp, ticks - tp->t_rtttime); 2812 } 2813 2814 /* 2815 * If all outstanding data is acked, stop retransmit 2816 * timer and remember to restart (more output or persist). 2817 * If there is more data to be acked, restart retransmit 2818 * timer, using current (possibly backed-off) value. 2819 */ 2820 if (th->th_ack == tp->snd_max) { 2821 tcp_timer_activate(tp, TT_REXMT, 0); 2822 needoutput = 1; 2823 } else if (!tcp_timer_active(tp, TT_PERSIST)) 2824 tcp_timer_activate(tp, TT_REXMT, tp->t_rxtcur); 2825 2826 /* 2827 * If no data (only SYN) was ACK'd, 2828 * skip rest of ACK processing. 2829 */ 2830 if (acked == 0) 2831 goto step6; 2832 2833 /* 2834 * Let the congestion control algorithm update congestion 2835 * control related information. This typically means increasing 2836 * the congestion window. 2837 */ 2838 cc_ack_received(tp, th, nsegs, CC_ACK); 2839 2840 SOCKBUF_LOCK(&so->so_snd); 2841 if (acked > sbavail(&so->so_snd)) { 2842 if (tp->snd_wnd >= sbavail(&so->so_snd)) 2843 tp->snd_wnd -= sbavail(&so->so_snd); 2844 else 2845 tp->snd_wnd = 0; 2846 mfree = sbcut_locked(&so->so_snd, 2847 (int)sbavail(&so->so_snd)); 2848 ourfinisacked = 1; 2849 } else { 2850 mfree = sbcut_locked(&so->so_snd, acked); 2851 if (tp->snd_wnd >= (uint32_t) acked) 2852 tp->snd_wnd -= acked; 2853 else 2854 tp->snd_wnd = 0; 2855 ourfinisacked = 0; 2856 } 2857 /* NB: sowwakeup_locked() does an implicit unlock. */ 2858 sowwakeup_locked(so); 2859 m_freem(mfree); 2860 /* Detect una wraparound. */ 2861 if (!IN_RECOVERY(tp->t_flags) && 2862 SEQ_GT(tp->snd_una, tp->snd_recover) && 2863 SEQ_LEQ(th->th_ack, tp->snd_recover)) 2864 tp->snd_recover = th->th_ack - 1; 2865 /* XXXLAS: Can this be moved up into cc_post_recovery? */ 2866 if (IN_RECOVERY(tp->t_flags) && 2867 SEQ_GEQ(th->th_ack, tp->snd_recover)) { 2868 EXIT_RECOVERY(tp->t_flags); 2869 } 2870 tp->snd_una = th->th_ack; 2871 if (tp->t_flags & TF_SACK_PERMIT) { 2872 if (SEQ_GT(tp->snd_una, tp->snd_recover)) 2873 tp->snd_recover = tp->snd_una; 2874 } 2875 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2876 tp->snd_nxt = tp->snd_una; 2877 2878 switch (tp->t_state) { 2879 2880 /* 2881 * In FIN_WAIT_1 STATE in addition to the processing 2882 * for the ESTABLISHED state if our FIN is now acknowledged 2883 * then enter FIN_WAIT_2. 2884 */ 2885 case TCPS_FIN_WAIT_1: 2886 if (ourfinisacked) { 2887 /* 2888 * If we can't receive any more 2889 * data, then closing user can proceed. 2890 * Starting the timer is contrary to the 2891 * specification, but if we don't get a FIN 2892 * we'll hang forever. 2893 * 2894 * XXXjl: 2895 * we should release the tp also, and use a 2896 * compressed state. 2897 */ 2898 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 2899 soisdisconnected(so); 2900 tcp_timer_activate(tp, TT_2MSL, 2901 (tcp_fast_finwait2_recycle ? 2902 tcp_finwait2_timeout : 2903 TP_MAXIDLE(tp))); 2904 } 2905 tcp_state_change(tp, TCPS_FIN_WAIT_2); 2906 } 2907 break; 2908 2909 /* 2910 * In CLOSING STATE in addition to the processing for 2911 * the ESTABLISHED state if the ACK acknowledges our FIN 2912 * then enter the TIME-WAIT state, otherwise ignore 2913 * the segment. 2914 */ 2915 case TCPS_CLOSING: 2916 if (ourfinisacked) { 2917 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 2918 tcp_twstart(tp); 2919 INP_INFO_RUNLOCK(&V_tcbinfo); 2920 m_freem(m); 2921 return; 2922 } 2923 break; 2924 2925 /* 2926 * In LAST_ACK, we may still be waiting for data to drain 2927 * and/or to be acked, as well as for the ack of our FIN. 2928 * If our FIN is now acknowledged, delete the TCB, 2929 * enter the closed state and return. 2930 */ 2931 case TCPS_LAST_ACK: 2932 if (ourfinisacked) { 2933 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 2934 tp = tcp_close(tp); 2935 goto drop; 2936 } 2937 break; 2938 } 2939 } 2940 2941 step6: 2942 INP_WLOCK_ASSERT(tp->t_inpcb); 2943 2944 /* 2945 * Update window information. 2946 * Don't look at window if no ACK: TAC's send garbage on first SYN. 2947 */ 2948 if ((thflags & TH_ACK) && 2949 (SEQ_LT(tp->snd_wl1, th->th_seq) || 2950 (tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) || 2951 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) { 2952 /* keep track of pure window updates */ 2953 if (tlen == 0 && 2954 tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) 2955 TCPSTAT_INC(tcps_rcvwinupd); 2956 tp->snd_wnd = tiwin; 2957 tp->snd_wl1 = th->th_seq; 2958 tp->snd_wl2 = th->th_ack; 2959 if (tp->snd_wnd > tp->max_sndwnd) 2960 tp->max_sndwnd = tp->snd_wnd; 2961 needoutput = 1; 2962 } 2963 2964 /* 2965 * Process segments with URG. 2966 */ 2967 if ((thflags & TH_URG) && th->th_urp && 2968 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2969 /* 2970 * This is a kludge, but if we receive and accept 2971 * random urgent pointers, we'll crash in 2972 * soreceive. It's hard to imagine someone 2973 * actually wanting to send this much urgent data. 2974 */ 2975 SOCKBUF_LOCK(&so->so_rcv); 2976 if (th->th_urp + sbavail(&so->so_rcv) > sb_max) { 2977 th->th_urp = 0; /* XXX */ 2978 thflags &= ~TH_URG; /* XXX */ 2979 SOCKBUF_UNLOCK(&so->so_rcv); /* XXX */ 2980 goto dodata; /* XXX */ 2981 } 2982 /* 2983 * If this segment advances the known urgent pointer, 2984 * then mark the data stream. This should not happen 2985 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 2986 * a FIN has been received from the remote side. 2987 * In these states we ignore the URG. 2988 * 2989 * According to RFC961 (Assigned Protocols), 2990 * the urgent pointer points to the last octet 2991 * of urgent data. We continue, however, 2992 * to consider it to indicate the first octet 2993 * of data past the urgent section as the original 2994 * spec states (in one of two places). 2995 */ 2996 if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) { 2997 tp->rcv_up = th->th_seq + th->th_urp; 2998 so->so_oobmark = sbavail(&so->so_rcv) + 2999 (tp->rcv_up - tp->rcv_nxt) - 1; 3000 if (so->so_oobmark == 0) 3001 so->so_rcv.sb_state |= SBS_RCVATMARK; 3002 sohasoutofband(so); 3003 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); 3004 } 3005 SOCKBUF_UNLOCK(&so->so_rcv); 3006 /* 3007 * Remove out of band data so doesn't get presented to user. 3008 * This can happen independent of advancing the URG pointer, 3009 * but if two URG's are pending at once, some out-of-band 3010 * data may creep in... ick. 3011 */ 3012 if (th->th_urp <= (uint32_t)tlen && 3013 !(so->so_options & SO_OOBINLINE)) { 3014 /* hdr drop is delayed */ 3015 tcp_pulloutofband(so, th, m, drop_hdrlen); 3016 } 3017 } else { 3018 /* 3019 * If no out of band data is expected, 3020 * pull receive urgent pointer along 3021 * with the receive window. 3022 */ 3023 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) 3024 tp->rcv_up = tp->rcv_nxt; 3025 } 3026 dodata: /* XXX */ 3027 INP_WLOCK_ASSERT(tp->t_inpcb); 3028 3029 /* 3030 * Process the segment text, merging it into the TCP sequencing queue, 3031 * and arranging for acknowledgment of receipt if necessary. 3032 * This process logically involves adjusting tp->rcv_wnd as data 3033 * is presented to the user (this happens in tcp_usrreq.c, 3034 * case PRU_RCVD). If a FIN has already been received on this 3035 * connection then we just ignore the text. 3036 */ 3037 #ifdef TCP_RFC7413 3038 tfo_syn = ((tp->t_state == TCPS_SYN_RECEIVED) && 3039 IS_FASTOPEN(tp->t_flags)); 3040 #else 3041 #define tfo_syn (false) 3042 #endif 3043 if ((tlen || (thflags & TH_FIN) || tfo_syn) && 3044 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3045 tcp_seq save_start = th->th_seq; 3046 m_adj(m, drop_hdrlen); /* delayed header drop */ 3047 /* 3048 * Insert segment which includes th into TCP reassembly queue 3049 * with control block tp. Set thflags to whether reassembly now 3050 * includes a segment with FIN. This handles the common case 3051 * inline (segment is the next to be received on an established 3052 * connection, and the queue is empty), avoiding linkage into 3053 * and removal from the queue and repetition of various 3054 * conversions. 3055 * Set DELACK for segments received in order, but ack 3056 * immediately when segments are out of order (so 3057 * fast retransmit can work). 3058 */ 3059 if (th->th_seq == tp->rcv_nxt && 3060 LIST_EMPTY(&tp->t_segq) && 3061 (TCPS_HAVEESTABLISHED(tp->t_state) || 3062 tfo_syn)) { 3063 if (DELAY_ACK(tp, tlen) || tfo_syn) 3064 tp->t_flags |= TF_DELACK; 3065 else 3066 tp->t_flags |= TF_ACKNOW; 3067 tp->rcv_nxt += tlen; 3068 thflags = th->th_flags & TH_FIN; 3069 TCPSTAT_INC(tcps_rcvpack); 3070 TCPSTAT_ADD(tcps_rcvbyte, tlen); 3071 SOCKBUF_LOCK(&so->so_rcv); 3072 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) 3073 m_freem(m); 3074 else 3075 sbappendstream_locked(&so->so_rcv, m, 0); 3076 /* NB: sorwakeup_locked() does an implicit unlock. */ 3077 sorwakeup_locked(so); 3078 } else { 3079 /* 3080 * XXX: Due to the header drop above "th" is 3081 * theoretically invalid by now. Fortunately 3082 * m_adj() doesn't actually frees any mbufs 3083 * when trimming from the head. 3084 */ 3085 thflags = tcp_reass(tp, th, &tlen, m); 3086 tp->t_flags |= TF_ACKNOW; 3087 } 3088 if (tlen > 0 && (tp->t_flags & TF_SACK_PERMIT)) 3089 tcp_update_sack_list(tp, save_start, save_start + tlen); 3090 #if 0 3091 /* 3092 * Note the amount of data that peer has sent into 3093 * our window, in order to estimate the sender's 3094 * buffer size. 3095 * XXX: Unused. 3096 */ 3097 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt)) 3098 len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); 3099 else 3100 len = so->so_rcv.sb_hiwat; 3101 #endif 3102 } else { 3103 m_freem(m); 3104 thflags &= ~TH_FIN; 3105 } 3106 3107 /* 3108 * If FIN is received ACK the FIN and let the user know 3109 * that the connection is closing. 3110 */ 3111 if (thflags & TH_FIN) { 3112 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3113 socantrcvmore(so); 3114 /* 3115 * If connection is half-synchronized 3116 * (ie NEEDSYN flag on) then delay ACK, 3117 * so it may be piggybacked when SYN is sent. 3118 * Otherwise, since we received a FIN then no 3119 * more input can be expected, send ACK now. 3120 */ 3121 if (tp->t_flags & TF_NEEDSYN) 3122 tp->t_flags |= TF_DELACK; 3123 else 3124 tp->t_flags |= TF_ACKNOW; 3125 tp->rcv_nxt++; 3126 } 3127 switch (tp->t_state) { 3128 3129 /* 3130 * In SYN_RECEIVED and ESTABLISHED STATES 3131 * enter the CLOSE_WAIT state. 3132 */ 3133 case TCPS_SYN_RECEIVED: 3134 tp->t_starttime = ticks; 3135 /* FALLTHROUGH */ 3136 case TCPS_ESTABLISHED: 3137 tcp_state_change(tp, TCPS_CLOSE_WAIT); 3138 break; 3139 3140 /* 3141 * If still in FIN_WAIT_1 STATE FIN has not been acked so 3142 * enter the CLOSING state. 3143 */ 3144 case TCPS_FIN_WAIT_1: 3145 tcp_state_change(tp, TCPS_CLOSING); 3146 break; 3147 3148 /* 3149 * In FIN_WAIT_2 state enter the TIME_WAIT state, 3150 * starting the time-wait timer, turning off the other 3151 * standard timers. 3152 */ 3153 case TCPS_FIN_WAIT_2: 3154 INP_INFO_RLOCK_ASSERT(&V_tcbinfo); 3155 KASSERT(ti_locked == TI_RLOCKED, ("%s: dodata " 3156 "TCP_FIN_WAIT_2 ti_locked: %d", __func__, 3157 ti_locked)); 3158 3159 tcp_twstart(tp); 3160 INP_INFO_RUNLOCK(&V_tcbinfo); 3161 return; 3162 } 3163 } 3164 if (ti_locked == TI_RLOCKED) 3165 INP_INFO_RUNLOCK(&V_tcbinfo); 3166 ti_locked = TI_UNLOCKED; 3167 3168 #ifdef TCPDEBUG 3169 if (so->so_options & SO_DEBUG) 3170 tcp_trace(TA_INPUT, ostate, tp, (void *)tcp_saveipgen, 3171 &tcp_savetcp, 0); 3172 #endif 3173 TCP_PROBE3(debug__input, tp, th, m); 3174 3175 /* 3176 * Return any desired output. 3177 */ 3178 if (needoutput || (tp->t_flags & TF_ACKNOW)) 3179 (void) tp->t_fb->tfb_tcp_output(tp); 3180 3181 check_delack: 3182 KASSERT(ti_locked == TI_UNLOCKED, ("%s: check_delack ti_locked %d", 3183 __func__, ti_locked)); 3184 INP_INFO_UNLOCK_ASSERT(&V_tcbinfo); 3185 INP_WLOCK_ASSERT(tp->t_inpcb); 3186 3187 if (tp->t_flags & TF_DELACK) { 3188 tp->t_flags &= ~TF_DELACK; 3189 tcp_timer_activate(tp, TT_DELACK, tcp_delacktime); 3190 } 3191 INP_WUNLOCK(tp->t_inpcb); 3192 return; 3193 3194 dropafterack: 3195 /* 3196 * Generate an ACK dropping incoming segment if it occupies 3197 * sequence space, where the ACK reflects our state. 3198 * 3199 * We can now skip the test for the RST flag since all 3200 * paths to this code happen after packets containing 3201 * RST have been dropped. 3202 * 3203 * In the SYN-RECEIVED state, don't send an ACK unless the 3204 * segment we received passes the SYN-RECEIVED ACK test. 3205 * If it fails send a RST. This breaks the loop in the 3206 * "LAND" DoS attack, and also prevents an ACK storm 3207 * between two listening ports that have been sent forged 3208 * SYN segments, each with the source address of the other. 3209 */ 3210 if (tp->t_state == TCPS_SYN_RECEIVED && (thflags & TH_ACK) && 3211 (SEQ_GT(tp->snd_una, th->th_ack) || 3212 SEQ_GT(th->th_ack, tp->snd_max)) ) { 3213 rstreason = BANDLIM_RST_OPENPORT; 3214 goto dropwithreset; 3215 } 3216 #ifdef TCPDEBUG 3217 if (so->so_options & SO_DEBUG) 3218 tcp_trace(TA_DROP, ostate, tp, (void *)tcp_saveipgen, 3219 &tcp_savetcp, 0); 3220 #endif 3221 TCP_PROBE3(debug__input, tp, th, m); 3222 if (ti_locked == TI_RLOCKED) 3223 INP_INFO_RUNLOCK(&V_tcbinfo); 3224 ti_locked = TI_UNLOCKED; 3225 3226 tp->t_flags |= TF_ACKNOW; 3227 (void) tp->t_fb->tfb_tcp_output(tp); 3228 INP_WUNLOCK(tp->t_inpcb); 3229 m_freem(m); 3230 return; 3231 3232 dropwithreset: 3233 if (ti_locked == TI_RLOCKED) 3234 INP_INFO_RUNLOCK(&V_tcbinfo); 3235 ti_locked = TI_UNLOCKED; 3236 3237 if (tp != NULL) { 3238 tcp_dropwithreset(m, th, tp, tlen, rstreason); 3239 INP_WUNLOCK(tp->t_inpcb); 3240 } else 3241 tcp_dropwithreset(m, th, NULL, tlen, rstreason); 3242 return; 3243 3244 drop: 3245 if (ti_locked == TI_RLOCKED) { 3246 INP_INFO_RUNLOCK(&V_tcbinfo); 3247 ti_locked = TI_UNLOCKED; 3248 } 3249 #ifdef INVARIANTS 3250 else 3251 INP_INFO_UNLOCK_ASSERT(&V_tcbinfo); 3252 #endif 3253 3254 /* 3255 * Drop space held by incoming segment and return. 3256 */ 3257 #ifdef TCPDEBUG 3258 if (tp == NULL || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 3259 tcp_trace(TA_DROP, ostate, tp, (void *)tcp_saveipgen, 3260 &tcp_savetcp, 0); 3261 #endif 3262 TCP_PROBE3(debug__input, tp, th, m); 3263 if (tp != NULL) 3264 INP_WUNLOCK(tp->t_inpcb); 3265 m_freem(m); 3266 #ifndef TCP_RFC7413 3267 #undef tfo_syn 3268 #endif 3269 } 3270 3271 /* 3272 * Issue RST and make ACK acceptable to originator of segment. 3273 * The mbuf must still include the original packet header. 3274 * tp may be NULL. 3275 */ 3276 void 3277 tcp_dropwithreset(struct mbuf *m, struct tcphdr *th, struct tcpcb *tp, 3278 int tlen, int rstreason) 3279 { 3280 #ifdef INET 3281 struct ip *ip; 3282 #endif 3283 #ifdef INET6 3284 struct ip6_hdr *ip6; 3285 #endif 3286 3287 if (tp != NULL) { 3288 INP_WLOCK_ASSERT(tp->t_inpcb); 3289 } 3290 3291 /* Don't bother if destination was broadcast/multicast. */ 3292 if ((th->th_flags & TH_RST) || m->m_flags & (M_BCAST|M_MCAST)) 3293 goto drop; 3294 #ifdef INET6 3295 if (mtod(m, struct ip *)->ip_v == 6) { 3296 ip6 = mtod(m, struct ip6_hdr *); 3297 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 3298 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) 3299 goto drop; 3300 /* IPv6 anycast check is done at tcp6_input() */ 3301 } 3302 #endif 3303 #if defined(INET) && defined(INET6) 3304 else 3305 #endif 3306 #ifdef INET 3307 { 3308 ip = mtod(m, struct ip *); 3309 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 3310 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 3311 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || 3312 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 3313 goto drop; 3314 } 3315 #endif 3316 3317 /* Perform bandwidth limiting. */ 3318 if (badport_bandlim(rstreason) < 0) 3319 goto drop; 3320 3321 /* tcp_respond consumes the mbuf chain. */ 3322 if (th->th_flags & TH_ACK) { 3323 tcp_respond(tp, mtod(m, void *), th, m, (tcp_seq)0, 3324 th->th_ack, TH_RST); 3325 } else { 3326 if (th->th_flags & TH_SYN) 3327 tlen++; 3328 if (th->th_flags & TH_FIN) 3329 tlen++; 3330 tcp_respond(tp, mtod(m, void *), th, m, th->th_seq+tlen, 3331 (tcp_seq)0, TH_RST|TH_ACK); 3332 } 3333 return; 3334 drop: 3335 m_freem(m); 3336 } 3337 3338 /* 3339 * Parse TCP options and place in tcpopt. 3340 */ 3341 void 3342 tcp_dooptions(struct tcpopt *to, u_char *cp, int cnt, int flags) 3343 { 3344 int opt, optlen; 3345 3346 to->to_flags = 0; 3347 for (; cnt > 0; cnt -= optlen, cp += optlen) { 3348 opt = cp[0]; 3349 if (opt == TCPOPT_EOL) 3350 break; 3351 if (opt == TCPOPT_NOP) 3352 optlen = 1; 3353 else { 3354 if (cnt < 2) 3355 break; 3356 optlen = cp[1]; 3357 if (optlen < 2 || optlen > cnt) 3358 break; 3359 } 3360 switch (opt) { 3361 case TCPOPT_MAXSEG: 3362 if (optlen != TCPOLEN_MAXSEG) 3363 continue; 3364 if (!(flags & TO_SYN)) 3365 continue; 3366 to->to_flags |= TOF_MSS; 3367 bcopy((char *)cp + 2, 3368 (char *)&to->to_mss, sizeof(to->to_mss)); 3369 to->to_mss = ntohs(to->to_mss); 3370 break; 3371 case TCPOPT_WINDOW: 3372 if (optlen != TCPOLEN_WINDOW) 3373 continue; 3374 if (!(flags & TO_SYN)) 3375 continue; 3376 to->to_flags |= TOF_SCALE; 3377 to->to_wscale = min(cp[2], TCP_MAX_WINSHIFT); 3378 break; 3379 case TCPOPT_TIMESTAMP: 3380 if (optlen != TCPOLEN_TIMESTAMP) 3381 continue; 3382 to->to_flags |= TOF_TS; 3383 bcopy((char *)cp + 2, 3384 (char *)&to->to_tsval, sizeof(to->to_tsval)); 3385 to->to_tsval = ntohl(to->to_tsval); 3386 bcopy((char *)cp + 6, 3387 (char *)&to->to_tsecr, sizeof(to->to_tsecr)); 3388 to->to_tsecr = ntohl(to->to_tsecr); 3389 break; 3390 case TCPOPT_SIGNATURE: 3391 /* 3392 * In order to reply to a host which has set the 3393 * TCP_SIGNATURE option in its initial SYN, we have 3394 * to record the fact that the option was observed 3395 * here for the syncache code to perform the correct 3396 * response. 3397 */ 3398 if (optlen != TCPOLEN_SIGNATURE) 3399 continue; 3400 to->to_flags |= TOF_SIGNATURE; 3401 to->to_signature = cp + 2; 3402 break; 3403 case TCPOPT_SACK_PERMITTED: 3404 if (optlen != TCPOLEN_SACK_PERMITTED) 3405 continue; 3406 if (!(flags & TO_SYN)) 3407 continue; 3408 if (!V_tcp_do_sack) 3409 continue; 3410 to->to_flags |= TOF_SACKPERM; 3411 break; 3412 case TCPOPT_SACK: 3413 if (optlen <= 2 || (optlen - 2) % TCPOLEN_SACK != 0) 3414 continue; 3415 if (flags & TO_SYN) 3416 continue; 3417 to->to_flags |= TOF_SACK; 3418 to->to_nsacks = (optlen - 2) / TCPOLEN_SACK; 3419 to->to_sacks = cp + 2; 3420 TCPSTAT_INC(tcps_sack_rcv_blocks); 3421 break; 3422 #ifdef TCP_RFC7413 3423 case TCPOPT_FAST_OPEN: 3424 if ((optlen != TCPOLEN_FAST_OPEN_EMPTY) && 3425 (optlen < TCPOLEN_FAST_OPEN_MIN) && 3426 (optlen > TCPOLEN_FAST_OPEN_MAX)) 3427 continue; 3428 if (!(flags & TO_SYN)) 3429 continue; 3430 if (!V_tcp_fastopen_enabled) 3431 continue; 3432 to->to_flags |= TOF_FASTOPEN; 3433 to->to_tfo_len = optlen - 2; 3434 to->to_tfo_cookie = to->to_tfo_len ? cp + 2 : NULL; 3435 break; 3436 #endif 3437 default: 3438 continue; 3439 } 3440 } 3441 } 3442 3443 /* 3444 * Pull out of band byte out of a segment so 3445 * it doesn't appear in the user's data queue. 3446 * It is still reflected in the segment length for 3447 * sequencing purposes. 3448 */ 3449 void 3450 tcp_pulloutofband(struct socket *so, struct tcphdr *th, struct mbuf *m, 3451 int off) 3452 { 3453 int cnt = off + th->th_urp - 1; 3454 3455 while (cnt >= 0) { 3456 if (m->m_len > cnt) { 3457 char *cp = mtod(m, caddr_t) + cnt; 3458 struct tcpcb *tp = sototcpcb(so); 3459 3460 INP_WLOCK_ASSERT(tp->t_inpcb); 3461 3462 tp->t_iobc = *cp; 3463 tp->t_oobflags |= TCPOOB_HAVEDATA; 3464 bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); 3465 m->m_len--; 3466 if (m->m_flags & M_PKTHDR) 3467 m->m_pkthdr.len--; 3468 return; 3469 } 3470 cnt -= m->m_len; 3471 m = m->m_next; 3472 if (m == NULL) 3473 break; 3474 } 3475 panic("tcp_pulloutofband"); 3476 } 3477 3478 /* 3479 * Collect new round-trip time estimate 3480 * and update averages and current timeout. 3481 */ 3482 void 3483 tcp_xmit_timer(struct tcpcb *tp, int rtt) 3484 { 3485 int delta; 3486 3487 INP_WLOCK_ASSERT(tp->t_inpcb); 3488 3489 TCPSTAT_INC(tcps_rttupdated); 3490 tp->t_rttupdated++; 3491 if ((tp->t_srtt != 0) && (tp->t_rxtshift <= TCP_RTT_INVALIDATE)) { 3492 /* 3493 * srtt is stored as fixed point with 5 bits after the 3494 * binary point (i.e., scaled by 8). The following magic 3495 * is equivalent to the smoothing algorithm in rfc793 with 3496 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed 3497 * point). Adjust rtt to origin 0. 3498 */ 3499 delta = ((rtt - 1) << TCP_DELTA_SHIFT) 3500 - (tp->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT)); 3501 3502 if ((tp->t_srtt += delta) <= 0) 3503 tp->t_srtt = 1; 3504 3505 /* 3506 * We accumulate a smoothed rtt variance (actually, a 3507 * smoothed mean difference), then set the retransmit 3508 * timer to smoothed rtt + 4 times the smoothed variance. 3509 * rttvar is stored as fixed point with 4 bits after the 3510 * binary point (scaled by 16). The following is 3511 * equivalent to rfc793 smoothing with an alpha of .75 3512 * (rttvar = rttvar*3/4 + |delta| / 4). This replaces 3513 * rfc793's wired-in beta. 3514 */ 3515 if (delta < 0) 3516 delta = -delta; 3517 delta -= tp->t_rttvar >> (TCP_RTTVAR_SHIFT - TCP_DELTA_SHIFT); 3518 if ((tp->t_rttvar += delta) <= 0) 3519 tp->t_rttvar = 1; 3520 if (tp->t_rttbest > tp->t_srtt + tp->t_rttvar) 3521 tp->t_rttbest = tp->t_srtt + tp->t_rttvar; 3522 } else { 3523 /* 3524 * No rtt measurement yet - use the unsmoothed rtt. 3525 * Set the variance to half the rtt (so our first 3526 * retransmit happens at 3*rtt). 3527 */ 3528 tp->t_srtt = rtt << TCP_RTT_SHIFT; 3529 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1); 3530 tp->t_rttbest = tp->t_srtt + tp->t_rttvar; 3531 } 3532 tp->t_rtttime = 0; 3533 tp->t_rxtshift = 0; 3534 3535 /* 3536 * the retransmit should happen at rtt + 4 * rttvar. 3537 * Because of the way we do the smoothing, srtt and rttvar 3538 * will each average +1/2 tick of bias. When we compute 3539 * the retransmit timer, we want 1/2 tick of rounding and 3540 * 1 extra tick because of +-1/2 tick uncertainty in the 3541 * firing of the timer. The bias will give us exactly the 3542 * 1.5 tick we need. But, because the bias is 3543 * statistical, we have to test that we don't drop below 3544 * the minimum feasible timer (which is 2 ticks). 3545 */ 3546 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), 3547 max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX); 3548 3549 /* 3550 * We received an ack for a packet that wasn't retransmitted; 3551 * it is probably safe to discard any error indications we've 3552 * received recently. This isn't quite right, but close enough 3553 * for now (a route might have failed after we sent a segment, 3554 * and the return path might not be symmetrical). 3555 */ 3556 tp->t_softerror = 0; 3557 } 3558 3559 /* 3560 * Determine a reasonable value for maxseg size. 3561 * If the route is known, check route for mtu. 3562 * If none, use an mss that can be handled on the outgoing interface 3563 * without forcing IP to fragment. If no route is found, route has no mtu, 3564 * or the destination isn't local, use a default, hopefully conservative 3565 * size (usually 512 or the default IP max size, but no more than the mtu 3566 * of the interface), as we can't discover anything about intervening 3567 * gateways or networks. We also initialize the congestion/slow start 3568 * window to be a single segment if the destination isn't local. 3569 * While looking at the routing entry, we also initialize other path-dependent 3570 * parameters from pre-set or cached values in the routing entry. 3571 * 3572 * NOTE that resulting t_maxseg doesn't include space for TCP options or 3573 * IP options, e.g. IPSEC data, since length of this data may vary, and 3574 * thus it is calculated for every segment separately in tcp_output(). 3575 * 3576 * NOTE that this routine is only called when we process an incoming 3577 * segment, or an ICMP need fragmentation datagram. Outgoing SYN/ACK MSS 3578 * settings are handled in tcp_mssopt(). 3579 */ 3580 void 3581 tcp_mss_update(struct tcpcb *tp, int offer, int mtuoffer, 3582 struct hc_metrics_lite *metricptr, struct tcp_ifcap *cap) 3583 { 3584 int mss = 0; 3585 uint32_t maxmtu = 0; 3586 struct inpcb *inp = tp->t_inpcb; 3587 struct hc_metrics_lite metrics; 3588 #ifdef INET6 3589 int isipv6 = ((inp->inp_vflag & INP_IPV6) != 0) ? 1 : 0; 3590 size_t min_protoh = isipv6 ? 3591 sizeof (struct ip6_hdr) + sizeof (struct tcphdr) : 3592 sizeof (struct tcpiphdr); 3593 #else 3594 const size_t min_protoh = sizeof(struct tcpiphdr); 3595 #endif 3596 3597 INP_WLOCK_ASSERT(tp->t_inpcb); 3598 3599 if (mtuoffer != -1) { 3600 KASSERT(offer == -1, ("%s: conflict", __func__)); 3601 offer = mtuoffer - min_protoh; 3602 } 3603 3604 /* Initialize. */ 3605 #ifdef INET6 3606 if (isipv6) { 3607 maxmtu = tcp_maxmtu6(&inp->inp_inc, cap); 3608 tp->t_maxseg = V_tcp_v6mssdflt; 3609 } 3610 #endif 3611 #if defined(INET) && defined(INET6) 3612 else 3613 #endif 3614 #ifdef INET 3615 { 3616 maxmtu = tcp_maxmtu(&inp->inp_inc, cap); 3617 tp->t_maxseg = V_tcp_mssdflt; 3618 } 3619 #endif 3620 3621 /* 3622 * No route to sender, stay with default mss and return. 3623 */ 3624 if (maxmtu == 0) { 3625 /* 3626 * In case we return early we need to initialize metrics 3627 * to a defined state as tcp_hc_get() would do for us 3628 * if there was no cache hit. 3629 */ 3630 if (metricptr != NULL) 3631 bzero(metricptr, sizeof(struct hc_metrics_lite)); 3632 return; 3633 } 3634 3635 /* What have we got? */ 3636 switch (offer) { 3637 case 0: 3638 /* 3639 * Offer == 0 means that there was no MSS on the SYN 3640 * segment, in this case we use tcp_mssdflt as 3641 * already assigned to t_maxseg above. 3642 */ 3643 offer = tp->t_maxseg; 3644 break; 3645 3646 case -1: 3647 /* 3648 * Offer == -1 means that we didn't receive SYN yet. 3649 */ 3650 /* FALLTHROUGH */ 3651 3652 default: 3653 /* 3654 * Prevent DoS attack with too small MSS. Round up 3655 * to at least minmss. 3656 */ 3657 offer = max(offer, V_tcp_minmss); 3658 } 3659 3660 /* 3661 * rmx information is now retrieved from tcp_hostcache. 3662 */ 3663 tcp_hc_get(&inp->inp_inc, &metrics); 3664 if (metricptr != NULL) 3665 bcopy(&metrics, metricptr, sizeof(struct hc_metrics_lite)); 3666 3667 /* 3668 * If there's a discovered mtu in tcp hostcache, use it. 3669 * Else, use the link mtu. 3670 */ 3671 if (metrics.rmx_mtu) 3672 mss = min(metrics.rmx_mtu, maxmtu) - min_protoh; 3673 else { 3674 #ifdef INET6 3675 if (isipv6) { 3676 mss = maxmtu - min_protoh; 3677 if (!V_path_mtu_discovery && 3678 !in6_localaddr(&inp->in6p_faddr)) 3679 mss = min(mss, V_tcp_v6mssdflt); 3680 } 3681 #endif 3682 #if defined(INET) && defined(INET6) 3683 else 3684 #endif 3685 #ifdef INET 3686 { 3687 mss = maxmtu - min_protoh; 3688 if (!V_path_mtu_discovery && 3689 !in_localaddr(inp->inp_faddr)) 3690 mss = min(mss, V_tcp_mssdflt); 3691 } 3692 #endif 3693 /* 3694 * XXX - The above conditional (mss = maxmtu - min_protoh) 3695 * probably violates the TCP spec. 3696 * The problem is that, since we don't know the 3697 * other end's MSS, we are supposed to use a conservative 3698 * default. But, if we do that, then MTU discovery will 3699 * never actually take place, because the conservative 3700 * default is much less than the MTUs typically seen 3701 * on the Internet today. For the moment, we'll sweep 3702 * this under the carpet. 3703 * 3704 * The conservative default might not actually be a problem 3705 * if the only case this occurs is when sending an initial 3706 * SYN with options and data to a host we've never talked 3707 * to before. Then, they will reply with an MSS value which 3708 * will get recorded and the new parameters should get 3709 * recomputed. For Further Study. 3710 */ 3711 } 3712 mss = min(mss, offer); 3713 3714 /* 3715 * Sanity check: make sure that maxseg will be large 3716 * enough to allow some data on segments even if the 3717 * all the option space is used (40bytes). Otherwise 3718 * funny things may happen in tcp_output. 3719 * 3720 * XXXGL: shouldn't we reserve space for IP/IPv6 options? 3721 */ 3722 mss = max(mss, 64); 3723 3724 tp->t_maxseg = mss; 3725 } 3726 3727 void 3728 tcp_mss(struct tcpcb *tp, int offer) 3729 { 3730 int mss; 3731 uint32_t bufsize; 3732 struct inpcb *inp; 3733 struct socket *so; 3734 struct hc_metrics_lite metrics; 3735 struct tcp_ifcap cap; 3736 3737 KASSERT(tp != NULL, ("%s: tp == NULL", __func__)); 3738 3739 bzero(&cap, sizeof(cap)); 3740 tcp_mss_update(tp, offer, -1, &metrics, &cap); 3741 3742 mss = tp->t_maxseg; 3743 inp = tp->t_inpcb; 3744 3745 /* 3746 * If there's a pipesize, change the socket buffer to that size, 3747 * don't change if sb_hiwat is different than default (then it 3748 * has been changed on purpose with setsockopt). 3749 * Make the socket buffers an integral number of mss units; 3750 * if the mss is larger than the socket buffer, decrease the mss. 3751 */ 3752 so = inp->inp_socket; 3753 SOCKBUF_LOCK(&so->so_snd); 3754 if ((so->so_snd.sb_hiwat == V_tcp_sendspace) && metrics.rmx_sendpipe) 3755 bufsize = metrics.rmx_sendpipe; 3756 else 3757 bufsize = so->so_snd.sb_hiwat; 3758 if (bufsize < mss) 3759 mss = bufsize; 3760 else { 3761 bufsize = roundup(bufsize, mss); 3762 if (bufsize > sb_max) 3763 bufsize = sb_max; 3764 if (bufsize > so->so_snd.sb_hiwat) 3765 (void)sbreserve_locked(&so->so_snd, bufsize, so, NULL); 3766 } 3767 SOCKBUF_UNLOCK(&so->so_snd); 3768 /* 3769 * Sanity check: make sure that maxseg will be large 3770 * enough to allow some data on segments even if the 3771 * all the option space is used (40bytes). Otherwise 3772 * funny things may happen in tcp_output. 3773 * 3774 * XXXGL: shouldn't we reserve space for IP/IPv6 options? 3775 */ 3776 tp->t_maxseg = max(mss, 64); 3777 3778 SOCKBUF_LOCK(&so->so_rcv); 3779 if ((so->so_rcv.sb_hiwat == V_tcp_recvspace) && metrics.rmx_recvpipe) 3780 bufsize = metrics.rmx_recvpipe; 3781 else 3782 bufsize = so->so_rcv.sb_hiwat; 3783 if (bufsize > mss) { 3784 bufsize = roundup(bufsize, mss); 3785 if (bufsize > sb_max) 3786 bufsize = sb_max; 3787 if (bufsize > so->so_rcv.sb_hiwat) 3788 (void)sbreserve_locked(&so->so_rcv, bufsize, so, NULL); 3789 } 3790 SOCKBUF_UNLOCK(&so->so_rcv); 3791 3792 /* Check the interface for TSO capabilities. */ 3793 if (cap.ifcap & CSUM_TSO) { 3794 tp->t_flags |= TF_TSO; 3795 tp->t_tsomax = cap.tsomax; 3796 tp->t_tsomaxsegcount = cap.tsomaxsegcount; 3797 tp->t_tsomaxsegsize = cap.tsomaxsegsize; 3798 } 3799 } 3800 3801 /* 3802 * Determine the MSS option to send on an outgoing SYN. 3803 */ 3804 int 3805 tcp_mssopt(struct in_conninfo *inc) 3806 { 3807 int mss = 0; 3808 uint32_t thcmtu = 0; 3809 uint32_t maxmtu = 0; 3810 size_t min_protoh; 3811 3812 KASSERT(inc != NULL, ("tcp_mssopt with NULL in_conninfo pointer")); 3813 3814 #ifdef INET6 3815 if (inc->inc_flags & INC_ISIPV6) { 3816 mss = V_tcp_v6mssdflt; 3817 maxmtu = tcp_maxmtu6(inc, NULL); 3818 min_protoh = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 3819 } 3820 #endif 3821 #if defined(INET) && defined(INET6) 3822 else 3823 #endif 3824 #ifdef INET 3825 { 3826 mss = V_tcp_mssdflt; 3827 maxmtu = tcp_maxmtu(inc, NULL); 3828 min_protoh = sizeof(struct tcpiphdr); 3829 } 3830 #endif 3831 #if defined(INET6) || defined(INET) 3832 thcmtu = tcp_hc_getmtu(inc); /* IPv4 and IPv6 */ 3833 #endif 3834 3835 if (maxmtu && thcmtu) 3836 mss = min(maxmtu, thcmtu) - min_protoh; 3837 else if (maxmtu || thcmtu) 3838 mss = max(maxmtu, thcmtu) - min_protoh; 3839 3840 return (mss); 3841 } 3842 3843 3844 /* 3845 * On a partial ack arrives, force the retransmission of the 3846 * next unacknowledged segment. Do not clear tp->t_dupacks. 3847 * By setting snd_nxt to ti_ack, this forces retransmission timer to 3848 * be started again. 3849 */ 3850 void 3851 tcp_newreno_partial_ack(struct tcpcb *tp, struct tcphdr *th) 3852 { 3853 tcp_seq onxt = tp->snd_nxt; 3854 uint32_t ocwnd = tp->snd_cwnd; 3855 u_int maxseg = tcp_maxseg(tp); 3856 3857 INP_WLOCK_ASSERT(tp->t_inpcb); 3858 3859 tcp_timer_activate(tp, TT_REXMT, 0); 3860 tp->t_rtttime = 0; 3861 tp->snd_nxt = th->th_ack; 3862 /* 3863 * Set snd_cwnd to one segment beyond acknowledged offset. 3864 * (tp->snd_una has not yet been updated when this function is called.) 3865 */ 3866 tp->snd_cwnd = maxseg + BYTES_THIS_ACK(tp, th); 3867 tp->t_flags |= TF_ACKNOW; 3868 (void) tp->t_fb->tfb_tcp_output(tp); 3869 tp->snd_cwnd = ocwnd; 3870 if (SEQ_GT(onxt, tp->snd_nxt)) 3871 tp->snd_nxt = onxt; 3872 /* 3873 * Partial window deflation. Relies on fact that tp->snd_una 3874 * not updated yet. 3875 */ 3876 if (tp->snd_cwnd > BYTES_THIS_ACK(tp, th)) 3877 tp->snd_cwnd -= BYTES_THIS_ACK(tp, th); 3878 else 3879 tp->snd_cwnd = 0; 3880 tp->snd_cwnd += maxseg; 3881 } 3882 3883 int 3884 tcp_compute_pipe(struct tcpcb *tp) 3885 { 3886 return (tp->snd_max - tp->snd_una + 3887 tp->sackhint.sack_bytes_rexmit - 3888 tp->sackhint.sacked_bytes); 3889 } 3890