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 50 #include <sys/cdefs.h> 51 #include "opt_inet.h" 52 #include "opt_inet6.h" 53 #include "opt_ipsec.h" 54 #include "opt_rss.h" 55 56 #include <sys/param.h> 57 #include <sys/arb.h> 58 #include <sys/kernel.h> 59 #ifdef TCP_HHOOK 60 #include <sys/hhook.h> 61 #endif 62 #include <sys/malloc.h> 63 #include <sys/mbuf.h> 64 #include <sys/proc.h> /* for proc0 declaration */ 65 #include <sys/protosw.h> 66 #include <sys/qmath.h> 67 #include <sys/sdt.h> 68 #include <sys/signalvar.h> 69 #include <sys/socket.h> 70 #include <sys/socketvar.h> 71 #include <sys/sysctl.h> 72 #include <sys/syslog.h> 73 #include <sys/systm.h> 74 #include <sys/stats.h> 75 76 #include <machine/cpu.h> /* before tcp_seq.h, for tcp_random18() */ 77 78 #include <vm/uma.h> 79 80 #include <net/if.h> 81 #include <net/if_var.h> 82 #include <net/route.h> 83 #include <net/rss_config.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_rss.h> 92 #include <netinet/in_systm.h> 93 #include <netinet/ip.h> 94 #include <netinet/ip_icmp.h> /* required for icmp_var.h */ 95 #include <netinet/icmp_var.h> /* for ICMP_BANDLIM */ 96 #include <netinet/ip_var.h> 97 #include <netinet/ip_options.h> 98 #include <netinet/ip6.h> 99 #include <netinet/icmp6.h> 100 #include <netinet6/in6_pcb.h> 101 #include <netinet6/in6_rss.h> 102 #include <netinet6/in6_var.h> 103 #include <netinet6/ip6_var.h> 104 #include <netinet6/nd6.h> 105 #include <netinet/tcp.h> 106 #include <netinet/tcp_fsm.h> 107 #include <netinet/tcp_seq.h> 108 #include <netinet/tcp_timer.h> 109 #include <netinet/tcp_var.h> 110 #include <netinet/tcp_log_buf.h> 111 #include <netinet6/tcp6_var.h> 112 #include <netinet/tcpip.h> 113 #include <netinet/cc/cc.h> 114 #include <netinet/tcp_fastopen.h> 115 #ifdef TCPPCAP 116 #include <netinet/tcp_pcap.h> 117 #endif 118 #include <netinet/tcp_syncache.h> 119 #ifdef TCP_OFFLOAD 120 #include <netinet/tcp_offload.h> 121 #endif 122 #include <netinet/tcp_ecn.h> 123 #include <netinet/udp.h> 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 VNET_DEFINE(int, tcp_log_in_vain) = 0; 134 SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_in_vain, CTLFLAG_VNET | CTLFLAG_RW, 135 &VNET_NAME(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(bool, blackhole_local) = false; 145 #define V_blackhole_local VNET(blackhole_local) 146 SYSCTL_BOOL(_net_inet_tcp, OID_AUTO, blackhole_local, CTLFLAG_VNET | 147 CTLFLAG_RW, &VNET_NAME(blackhole_local), false, 148 "Enforce net.inet.tcp.blackhole for locally originated packets"); 149 150 VNET_DEFINE(int, tcp_delack_enabled) = 1; 151 SYSCTL_INT(_net_inet_tcp, OID_AUTO, delayed_ack, CTLFLAG_VNET | CTLFLAG_RW, 152 &VNET_NAME(tcp_delack_enabled), 0, 153 "Delay ACK to try and piggyback it onto a data packet"); 154 155 VNET_DEFINE(int, drop_synfin) = 0; 156 SYSCTL_INT(_net_inet_tcp, OID_AUTO, drop_synfin, CTLFLAG_VNET | CTLFLAG_RW, 157 &VNET_NAME(drop_synfin), 0, 158 "Drop TCP packets with SYN+FIN set"); 159 160 VNET_DEFINE(int, tcp_do_prr) = 1; 161 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_prr, CTLFLAG_VNET | CTLFLAG_RW, 162 &VNET_NAME(tcp_do_prr), 1, 163 "Enable Proportional Rate Reduction per RFC 6937"); 164 165 VNET_DEFINE(int, tcp_do_newcwv) = 0; 166 SYSCTL_INT(_net_inet_tcp, OID_AUTO, newcwv, CTLFLAG_VNET | CTLFLAG_RW, 167 &VNET_NAME(tcp_do_newcwv), 0, 168 "Enable New Congestion Window Validation per RFC7661"); 169 170 VNET_DEFINE(int, tcp_do_rfc3042) = 1; 171 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3042, CTLFLAG_VNET | CTLFLAG_RW, 172 &VNET_NAME(tcp_do_rfc3042), 0, 173 "Enable RFC 3042 (Limited Transmit)"); 174 175 VNET_DEFINE(int, tcp_do_rfc3390) = 1; 176 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3390, CTLFLAG_VNET | CTLFLAG_RW, 177 &VNET_NAME(tcp_do_rfc3390), 0, 178 "Enable RFC 3390 (Increasing TCP's Initial Congestion Window)"); 179 180 VNET_DEFINE(int, tcp_initcwnd_segments) = 10; 181 SYSCTL_INT(_net_inet_tcp, OID_AUTO, initcwnd_segments, 182 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(tcp_initcwnd_segments), 0, 183 "Slow-start flight size (initial congestion window) in number of segments"); 184 185 VNET_DEFINE(int, tcp_do_rfc3465) = 1; 186 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3465, CTLFLAG_VNET | CTLFLAG_RW, 187 &VNET_NAME(tcp_do_rfc3465), 0, 188 "Enable RFC 3465 (Appropriate Byte Counting)"); 189 190 VNET_DEFINE(int, tcp_abc_l_var) = 2; 191 SYSCTL_INT(_net_inet_tcp, OID_AUTO, abc_l_var, CTLFLAG_VNET | CTLFLAG_RW, 192 &VNET_NAME(tcp_abc_l_var), 2, 193 "Cap the max cwnd increment during slow-start to this number of segments"); 194 195 VNET_DEFINE(int, tcp_insecure_syn) = 0; 196 SYSCTL_INT(_net_inet_tcp, OID_AUTO, insecure_syn, CTLFLAG_VNET | CTLFLAG_RW, 197 &VNET_NAME(tcp_insecure_syn), 0, 198 "Follow RFC793 instead of RFC5961 criteria for accepting SYN packets"); 199 200 VNET_DEFINE(int, tcp_insecure_rst) = 0; 201 SYSCTL_INT(_net_inet_tcp, OID_AUTO, insecure_rst, CTLFLAG_VNET | CTLFLAG_RW, 202 &VNET_NAME(tcp_insecure_rst), 0, 203 "Follow RFC793 instead of RFC5961 criteria for accepting RST packets"); 204 205 VNET_DEFINE(int, tcp_recvspace) = 1024*64; 206 #define V_tcp_recvspace VNET(tcp_recvspace) 207 SYSCTL_INT(_net_inet_tcp, TCPCTL_RECVSPACE, recvspace, CTLFLAG_VNET | CTLFLAG_RW, 208 &VNET_NAME(tcp_recvspace), 0, "Initial receive socket buffer size"); 209 210 VNET_DEFINE(int, tcp_do_autorcvbuf) = 1; 211 SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_auto, CTLFLAG_VNET | CTLFLAG_RW, 212 &VNET_NAME(tcp_do_autorcvbuf), 0, 213 "Enable automatic receive buffer sizing"); 214 215 VNET_DEFINE(int, tcp_autorcvbuf_max) = 2*1024*1024; 216 SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_max, CTLFLAG_VNET | CTLFLAG_RW, 217 &VNET_NAME(tcp_autorcvbuf_max), 0, 218 "Max size of automatic receive buffer"); 219 220 VNET_DEFINE(struct inpcbinfo, tcbinfo); 221 222 /* 223 * TCP statistics are stored in an array of counter(9)s, which size matches 224 * size of struct tcpstat. TCP running connection count is a regular array. 225 */ 226 VNET_PCPUSTAT_DEFINE(struct tcpstat, tcpstat); 227 SYSCTL_VNET_PCPUSTAT(_net_inet_tcp, TCPCTL_STATS, stats, struct tcpstat, 228 tcpstat, "TCP statistics (struct tcpstat, netinet/tcp_var.h)"); 229 VNET_DEFINE(counter_u64_t, tcps_states[TCP_NSTATES]); 230 SYSCTL_COUNTER_U64_ARRAY(_net_inet_tcp, TCPCTL_STATES, states, CTLFLAG_RD | 231 CTLFLAG_VNET, &VNET_NAME(tcps_states)[0], TCP_NSTATES, 232 "TCP connection counts by TCP state"); 233 234 /* 235 * Kernel module interface for updating tcpstat. The first argument is an index 236 * into tcpstat treated as an array. 237 */ 238 void 239 kmod_tcpstat_add(int statnum, int val) 240 { 241 242 counter_u64_add(VNET(tcpstat)[statnum], val); 243 } 244 245 /* 246 * Make sure that we only start a SACK loss recovery when 247 * receiving a duplicate ACK with a SACK block, and also 248 * complete SACK loss recovery in case the other end 249 * reneges. 250 */ 251 static bool inline 252 tcp_is_sack_recovery(struct tcpcb *tp, struct tcpopt *to) 253 { 254 return ((tp->t_flags & TF_SACK_PERMIT) && 255 ((to->to_flags & TOF_SACK) || 256 (!TAILQ_EMPTY(&tp->snd_holes)))); 257 } 258 259 #ifdef TCP_HHOOK 260 /* 261 * Wrapper for the TCP established input helper hook. 262 */ 263 void 264 hhook_run_tcp_est_in(struct tcpcb *tp, struct tcphdr *th, struct tcpopt *to) 265 { 266 struct tcp_hhook_data hhook_data; 267 268 if (V_tcp_hhh[HHOOK_TCP_EST_IN]->hhh_nhooks > 0) { 269 hhook_data.tp = tp; 270 hhook_data.th = th; 271 hhook_data.to = to; 272 273 hhook_run_hooks(V_tcp_hhh[HHOOK_TCP_EST_IN], &hhook_data, 274 &tp->t_osd); 275 } 276 } 277 #endif 278 279 /* 280 * CC wrapper hook functions 281 */ 282 void 283 cc_ack_received(struct tcpcb *tp, struct tcphdr *th, uint16_t nsegs, 284 uint16_t type) 285 { 286 #ifdef STATS 287 int32_t gput; 288 #endif 289 290 INP_WLOCK_ASSERT(tptoinpcb(tp)); 291 292 tp->t_ccv.nsegs = nsegs; 293 tp->t_ccv.bytes_this_ack = BYTES_THIS_ACK(tp, th); 294 if ((!V_tcp_do_newcwv && (tp->snd_cwnd <= tp->snd_wnd)) || 295 (V_tcp_do_newcwv && (tp->snd_cwnd <= tp->snd_wnd) && 296 (tp->snd_cwnd < (tcp_compute_pipe(tp) * 2)))) 297 tp->t_ccv.flags |= CCF_CWND_LIMITED; 298 else 299 tp->t_ccv.flags &= ~CCF_CWND_LIMITED; 300 301 if (type == CC_ACK) { 302 #ifdef STATS 303 stats_voi_update_abs_s32(tp->t_stats, VOI_TCP_CALCFRWINDIFF, 304 ((int32_t)tp->snd_cwnd) - tp->snd_wnd); 305 if (!IN_RECOVERY(tp->t_flags)) 306 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_ACKLEN, 307 tp->t_ccv.bytes_this_ack / (tcp_maxseg(tp) * nsegs)); 308 if ((tp->t_flags & TF_GPUTINPROG) && 309 SEQ_GEQ(th->th_ack, tp->gput_ack)) { 310 /* 311 * Compute goodput in bits per millisecond. 312 */ 313 gput = (((int64_t)SEQ_SUB(th->th_ack, tp->gput_seq)) << 3) / 314 max(1, tcp_ts_getticks() - tp->gput_ts); 315 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_GPUT, 316 gput); 317 /* 318 * XXXLAS: This is a temporary hack, and should be 319 * chained off VOI_TCP_GPUT when stats(9) grows an API 320 * to deal with chained VOIs. 321 */ 322 if (tp->t_stats_gput_prev > 0) 323 stats_voi_update_abs_s32(tp->t_stats, 324 VOI_TCP_GPUT_ND, 325 ((gput - tp->t_stats_gput_prev) * 100) / 326 tp->t_stats_gput_prev); 327 tp->t_flags &= ~TF_GPUTINPROG; 328 tp->t_stats_gput_prev = gput; 329 } 330 #endif /* STATS */ 331 if (tp->snd_cwnd > tp->snd_ssthresh) { 332 tp->t_bytes_acked += tp->t_ccv.bytes_this_ack; 333 if (tp->t_bytes_acked >= tp->snd_cwnd) { 334 tp->t_bytes_acked -= tp->snd_cwnd; 335 tp->t_ccv.flags |= CCF_ABC_SENTAWND; 336 } 337 } else { 338 tp->t_ccv.flags &= ~CCF_ABC_SENTAWND; 339 tp->t_bytes_acked = 0; 340 } 341 } 342 343 if (CC_ALGO(tp)->ack_received != NULL) { 344 /* XXXLAS: Find a way to live without this */ 345 tp->t_ccv.curack = th->th_ack; 346 CC_ALGO(tp)->ack_received(&tp->t_ccv, type); 347 } 348 #ifdef STATS 349 stats_voi_update_abs_ulong(tp->t_stats, VOI_TCP_LCWIN, tp->snd_cwnd); 350 #endif 351 } 352 353 void 354 cc_conn_init(struct tcpcb *tp) 355 { 356 struct hc_metrics_lite metrics; 357 struct inpcb *inp = tptoinpcb(tp); 358 u_int maxseg; 359 int rtt; 360 361 INP_WLOCK_ASSERT(inp); 362 363 tcp_hc_get(&inp->inp_inc, &metrics); 364 maxseg = tcp_maxseg(tp); 365 366 if (tp->t_srtt == 0 && (rtt = metrics.rmx_rtt)) { 367 tp->t_srtt = rtt; 368 TCPSTAT_INC(tcps_usedrtt); 369 if (metrics.rmx_rttvar) { 370 tp->t_rttvar = metrics.rmx_rttvar; 371 TCPSTAT_INC(tcps_usedrttvar); 372 } else { 373 /* default variation is +- 1 rtt */ 374 tp->t_rttvar = 375 tp->t_srtt * TCP_RTTVAR_SCALE / TCP_RTT_SCALE; 376 } 377 TCPT_RANGESET(tp->t_rxtcur, 378 ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1, 379 tp->t_rttmin, TCPTV_REXMTMAX); 380 } 381 if (metrics.rmx_ssthresh) { 382 /* 383 * There's some sort of gateway or interface 384 * buffer limit on the path. Use this to set 385 * the slow start threshold, but set the 386 * threshold to no less than 2*mss. 387 */ 388 tp->snd_ssthresh = max(2 * maxseg, metrics.rmx_ssthresh); 389 TCPSTAT_INC(tcps_usedssthresh); 390 } 391 392 /* 393 * Set the initial slow-start flight size. 394 * 395 * If a SYN or SYN/ACK was lost and retransmitted, we have to 396 * reduce the initial CWND to one segment as congestion is likely 397 * requiring us to be cautious. 398 */ 399 if (tp->snd_cwnd == 1) 400 tp->snd_cwnd = maxseg; /* SYN(-ACK) lost */ 401 else 402 tp->snd_cwnd = tcp_compute_initwnd(maxseg); 403 404 if (CC_ALGO(tp)->conn_init != NULL) 405 CC_ALGO(tp)->conn_init(&tp->t_ccv); 406 } 407 408 void inline 409 cc_cong_signal(struct tcpcb *tp, struct tcphdr *th, uint32_t type) 410 { 411 INP_WLOCK_ASSERT(tptoinpcb(tp)); 412 413 #ifdef STATS 414 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_CSIG, type); 415 #endif 416 417 switch(type) { 418 case CC_NDUPACK: 419 if (!IN_FASTRECOVERY(tp->t_flags)) { 420 tp->snd_recover = tp->snd_max; 421 if (tp->t_flags2 & TF2_ECN_PERMIT) 422 tp->t_flags2 |= TF2_ECN_SND_CWR; 423 } 424 break; 425 case CC_ECN: 426 if (!IN_CONGRECOVERY(tp->t_flags) || 427 /* 428 * Allow ECN reaction on ACK to CWR, if 429 * that data segment was also CE marked. 430 */ 431 SEQ_GEQ(th->th_ack, tp->snd_recover)) { 432 EXIT_CONGRECOVERY(tp->t_flags); 433 TCPSTAT_INC(tcps_ecn_rcwnd); 434 tp->snd_recover = tp->snd_max + 1; 435 if (tp->t_flags2 & TF2_ECN_PERMIT) 436 tp->t_flags2 |= TF2_ECN_SND_CWR; 437 } 438 break; 439 case CC_RTO: 440 tp->t_dupacks = 0; 441 tp->t_bytes_acked = 0; 442 if ((tp->t_rxtshift > 1) || 443 !((tp->t_flags & TF_SACK_PERMIT) && 444 (!TAILQ_EMPTY(&tp->snd_holes)))) 445 EXIT_RECOVERY(tp->t_flags); 446 if (tp->t_flags2 & TF2_ECN_PERMIT) 447 tp->t_flags2 |= TF2_ECN_SND_CWR; 448 break; 449 case CC_RTO_ERR: 450 TCPSTAT_INC(tcps_sndrexmitbad); 451 /* RTO was unnecessary, so reset everything. */ 452 tp->snd_cwnd = tp->snd_cwnd_prev; 453 tp->snd_ssthresh = tp->snd_ssthresh_prev; 454 tp->snd_recover = tp->snd_recover_prev; 455 if (tp->t_flags & TF_WASFRECOVERY) 456 ENTER_FASTRECOVERY(tp->t_flags); 457 if (tp->t_flags & TF_WASCRECOVERY) 458 ENTER_CONGRECOVERY(tp->t_flags); 459 tp->snd_nxt = tp->snd_max; 460 tp->t_flags &= ~TF_PREVVALID; 461 tp->t_badrxtwin = 0; 462 break; 463 } 464 if (SEQ_LT(tp->snd_fack, tp->snd_una) || 465 SEQ_GT(tp->snd_fack, tp->snd_max)) { 466 tp->snd_fack = tp->snd_una; 467 } 468 469 if (CC_ALGO(tp)->cong_signal != NULL) { 470 if (th != NULL) 471 tp->t_ccv.curack = th->th_ack; 472 CC_ALGO(tp)->cong_signal(&tp->t_ccv, type); 473 } 474 } 475 476 void inline 477 cc_post_recovery(struct tcpcb *tp, struct tcphdr *th) 478 { 479 INP_WLOCK_ASSERT(tptoinpcb(tp)); 480 481 if (CC_ALGO(tp)->post_recovery != NULL) { 482 if (SEQ_LT(tp->snd_fack, th->th_ack) || 483 SEQ_GT(tp->snd_fack, tp->snd_max)) { 484 tp->snd_fack = th->th_ack; 485 } 486 tp->t_ccv.curack = th->th_ack; 487 CC_ALGO(tp)->post_recovery(&tp->t_ccv); 488 } 489 EXIT_RECOVERY(tp->t_flags); 490 491 tp->t_bytes_acked = 0; 492 tp->sackhint.delivered_data = 0; 493 tp->sackhint.prr_delivered = 0; 494 tp->sackhint.prr_out = 0; 495 } 496 497 /* 498 * Indicate whether this ack should be delayed. We can delay the ack if 499 * following conditions are met: 500 * - There is no delayed ack timer in progress. 501 * - Our last ack wasn't a 0-sized window. We never want to delay 502 * the ack that opens up a 0-sized window. 503 * - LRO wasn't used for this segment. We make sure by checking that the 504 * segment size is not larger than the MSS. 505 */ 506 #define DELAY_ACK(tp, tlen) \ 507 ((!tcp_timer_active(tp, TT_DELACK) && \ 508 (tp->t_flags & TF_RXWIN0SENT) == 0) && \ 509 (tlen <= tp->t_maxseg) && \ 510 (V_tcp_delack_enabled || (tp->t_flags & TF_NEEDSYN))) 511 512 void inline 513 cc_ecnpkt_handler_flags(struct tcpcb *tp, uint16_t flags, uint8_t iptos) 514 { 515 INP_WLOCK_ASSERT(tptoinpcb(tp)); 516 517 if (CC_ALGO(tp)->ecnpkt_handler != NULL) { 518 switch (iptos & IPTOS_ECN_MASK) { 519 case IPTOS_ECN_CE: 520 tp->t_ccv.flags |= CCF_IPHDR_CE; 521 break; 522 case IPTOS_ECN_ECT0: 523 /* FALLTHROUGH */ 524 case IPTOS_ECN_ECT1: 525 /* FALLTHROUGH */ 526 case IPTOS_ECN_NOTECT: 527 tp->t_ccv.flags &= ~CCF_IPHDR_CE; 528 break; 529 } 530 531 if (flags & TH_CWR) 532 tp->t_ccv.flags |= CCF_TCPHDR_CWR; 533 else 534 tp->t_ccv.flags &= ~CCF_TCPHDR_CWR; 535 536 CC_ALGO(tp)->ecnpkt_handler(&tp->t_ccv); 537 538 if (tp->t_ccv.flags & CCF_ACKNOW) { 539 tcp_timer_activate(tp, TT_DELACK, tcp_delacktime); 540 tp->t_flags |= TF_ACKNOW; 541 } 542 } 543 } 544 545 void inline 546 cc_ecnpkt_handler(struct tcpcb *tp, struct tcphdr *th, uint8_t iptos) 547 { 548 cc_ecnpkt_handler_flags(tp, tcp_get_flags(th), iptos); 549 } 550 551 /* 552 * TCP input handling is split into multiple parts: 553 * tcp6_input is a thin wrapper around tcp_input for the extended 554 * ip6_protox[] call format in ip6_input 555 * tcp_input handles primary segment validation, inpcb lookup and 556 * SYN processing on listen sockets 557 * tcp_do_segment processes the ACK and text of the segment for 558 * establishing, established and closing connections 559 */ 560 #ifdef INET6 561 int 562 tcp6_input_with_port(struct mbuf **mp, int *offp, int proto, uint16_t port) 563 { 564 struct mbuf *m; 565 struct in6_ifaddr *ia6; 566 struct ip6_hdr *ip6; 567 568 m = *mp; 569 if (m->m_len < *offp + sizeof(struct tcphdr)) { 570 m = m_pullup(m, *offp + sizeof(struct tcphdr)); 571 if (m == NULL) { 572 *mp = m; 573 TCPSTAT_INC(tcps_rcvshort); 574 return (IPPROTO_DONE); 575 } 576 } 577 578 /* 579 * draft-itojun-ipv6-tcp-to-anycast 580 * better place to put this in? 581 */ 582 ip6 = mtod(m, struct ip6_hdr *); 583 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false); 584 if (ia6 && (ia6->ia6_flags & IN6_IFF_ANYCAST)) { 585 icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR, 586 (caddr_t)&ip6->ip6_dst - (caddr_t)ip6); 587 *mp = NULL; 588 return (IPPROTO_DONE); 589 } 590 591 *mp = m; 592 return (tcp_input_with_port(mp, offp, proto, port)); 593 } 594 595 int 596 tcp6_input(struct mbuf **mp, int *offp, int proto) 597 { 598 599 return(tcp6_input_with_port(mp, offp, proto, 0)); 600 } 601 #endif /* INET6 */ 602 603 int 604 tcp_input_with_port(struct mbuf **mp, int *offp, int proto, uint16_t port) 605 { 606 struct mbuf *m = *mp; 607 struct tcphdr *th = NULL; 608 struct ip *ip = NULL; 609 struct inpcb *inp = NULL; 610 struct tcpcb *tp = NULL; 611 struct socket *so = NULL; 612 u_char *optp = NULL; 613 int off0; 614 int optlen = 0; 615 #ifdef INET 616 int len; 617 uint8_t ipttl; 618 #endif 619 int tlen = 0, off; 620 int drop_hdrlen; 621 int thflags; 622 int rstreason = 0; /* For badport_bandlim accounting purposes */ 623 int lookupflag; 624 uint8_t iptos; 625 struct m_tag *fwd_tag = NULL; 626 #ifdef INET6 627 struct ip6_hdr *ip6 = NULL; 628 int isipv6; 629 #else 630 const void *ip6 = NULL; 631 #endif /* INET6 */ 632 struct tcpopt to; /* options in this segment */ 633 char *s = NULL; /* address and port logging */ 634 635 NET_EPOCH_ASSERT(); 636 637 #ifdef INET6 638 isipv6 = (mtod(m, struct ip *)->ip_v == 6) ? 1 : 0; 639 #endif 640 641 off0 = *offp; 642 m = *mp; 643 *mp = NULL; 644 to.to_flags = 0; 645 TCPSTAT_INC(tcps_rcvtotal); 646 647 m->m_pkthdr.tcp_tun_port = port; 648 #ifdef INET6 649 if (isipv6) { 650 ip6 = mtod(m, struct ip6_hdr *); 651 th = (struct tcphdr *)((caddr_t)ip6 + off0); 652 tlen = sizeof(*ip6) + ntohs(ip6->ip6_plen) - off0; 653 if (port) 654 goto skip6_csum; 655 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID_IPV6) { 656 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 657 th->th_sum = m->m_pkthdr.csum_data; 658 else 659 th->th_sum = in6_cksum_pseudo(ip6, tlen, 660 IPPROTO_TCP, m->m_pkthdr.csum_data); 661 th->th_sum ^= 0xffff; 662 } else 663 th->th_sum = in6_cksum(m, IPPROTO_TCP, off0, tlen); 664 if (th->th_sum) { 665 TCPSTAT_INC(tcps_rcvbadsum); 666 goto drop; 667 } 668 skip6_csum: 669 /* 670 * Be proactive about unspecified IPv6 address in source. 671 * As we use all-zero to indicate unbounded/unconnected pcb, 672 * unspecified IPv6 address can be used to confuse us. 673 * 674 * Note that packets with unspecified IPv6 destination is 675 * already dropped in ip6_input. 676 */ 677 KASSERT(!IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_dst), 678 ("%s: unspecified destination v6 address", __func__)); 679 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 680 IP6STAT_INC(ip6s_badscope); /* XXX */ 681 goto drop; 682 } 683 iptos = IPV6_TRAFFIC_CLASS(ip6); 684 } 685 #endif 686 #if defined(INET) && defined(INET6) 687 else 688 #endif 689 #ifdef INET 690 { 691 /* 692 * Get IP and TCP header together in first mbuf. 693 * Note: IP leaves IP header in first mbuf. 694 */ 695 if (off0 > sizeof (struct ip)) { 696 ip_stripoptions(m); 697 off0 = sizeof(struct ip); 698 } 699 if (m->m_len < sizeof (struct tcpiphdr)) { 700 if ((m = m_pullup(m, sizeof (struct tcpiphdr))) 701 == NULL) { 702 TCPSTAT_INC(tcps_rcvshort); 703 return (IPPROTO_DONE); 704 } 705 } 706 ip = mtod(m, struct ip *); 707 th = (struct tcphdr *)((caddr_t)ip + off0); 708 tlen = ntohs(ip->ip_len) - off0; 709 710 iptos = ip->ip_tos; 711 if (port) 712 goto skip_csum; 713 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) { 714 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 715 th->th_sum = m->m_pkthdr.csum_data; 716 else 717 th->th_sum = in_pseudo(ip->ip_src.s_addr, 718 ip->ip_dst.s_addr, 719 htonl(m->m_pkthdr.csum_data + tlen + 720 IPPROTO_TCP)); 721 th->th_sum ^= 0xffff; 722 } else { 723 struct ipovly *ipov = (struct ipovly *)ip; 724 725 /* 726 * Checksum extended TCP header and data. 727 */ 728 len = off0 + tlen; 729 ipttl = ip->ip_ttl; 730 bzero(ipov->ih_x1, sizeof(ipov->ih_x1)); 731 ipov->ih_len = htons(tlen); 732 th->th_sum = in_cksum(m, len); 733 /* Reset length for SDT probes. */ 734 ip->ip_len = htons(len); 735 /* Reset TOS bits */ 736 ip->ip_tos = iptos; 737 /* Re-initialization for later version check */ 738 ip->ip_ttl = ipttl; 739 ip->ip_v = IPVERSION; 740 ip->ip_hl = off0 >> 2; 741 } 742 skip_csum: 743 if (th->th_sum && (port == 0)) { 744 TCPSTAT_INC(tcps_rcvbadsum); 745 goto drop; 746 } 747 KASSERT(ip->ip_dst.s_addr != INADDR_ANY, 748 ("%s: unspecified destination v4 address", __func__)); 749 if (__predict_false(ip->ip_src.s_addr == INADDR_ANY)) { 750 IPSTAT_INC(ips_badaddr); 751 goto drop; 752 } 753 } 754 #endif /* INET */ 755 756 /* 757 * Check that TCP offset makes sense, 758 * pull out TCP options and adjust length. XXX 759 */ 760 off = th->th_off << 2; 761 if (off < sizeof (struct tcphdr) || off > tlen) { 762 TCPSTAT_INC(tcps_rcvbadoff); 763 goto drop; 764 } 765 tlen -= off; /* tlen is used instead of ti->ti_len */ 766 if (off > sizeof (struct tcphdr)) { 767 #ifdef INET6 768 if (isipv6) { 769 if (m->m_len < off0 + off) { 770 m = m_pullup(m, off0 + off); 771 if (m == NULL) { 772 TCPSTAT_INC(tcps_rcvshort); 773 return (IPPROTO_DONE); 774 } 775 } 776 ip6 = mtod(m, struct ip6_hdr *); 777 th = (struct tcphdr *)((caddr_t)ip6 + off0); 778 } 779 #endif 780 #if defined(INET) && defined(INET6) 781 else 782 #endif 783 #ifdef INET 784 { 785 if (m->m_len < sizeof(struct ip) + off) { 786 if ((m = m_pullup(m, sizeof (struct ip) + off)) 787 == NULL) { 788 TCPSTAT_INC(tcps_rcvshort); 789 return (IPPROTO_DONE); 790 } 791 ip = mtod(m, struct ip *); 792 th = (struct tcphdr *)((caddr_t)ip + off0); 793 } 794 } 795 #endif 796 optlen = off - sizeof (struct tcphdr); 797 optp = (u_char *)(th + 1); 798 } 799 thflags = tcp_get_flags(th); 800 801 /* 802 * Convert TCP protocol specific fields to host format. 803 */ 804 tcp_fields_to_host(th); 805 806 /* 807 * Delay dropping TCP, IP headers, IPv6 ext headers, and TCP options. 808 */ 809 drop_hdrlen = off0 + off; 810 811 /* 812 * Grab info from PACKET_TAG_IPFORWARD tag prepended to the chain. 813 */ 814 if ( 815 #ifdef INET6 816 (isipv6 && (m->m_flags & M_IP6_NEXTHOP)) 817 #ifdef INET 818 || (!isipv6 && (m->m_flags & M_IP_NEXTHOP)) 819 #endif 820 #endif 821 #if defined(INET) && !defined(INET6) 822 (m->m_flags & M_IP_NEXTHOP) 823 #endif 824 ) 825 fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL); 826 827 /* 828 * For initial SYN packets we don't need write lock on matching 829 * PCB, be it a listening one or a synchronized one. The packet 830 * shall not modify its state. 831 */ 832 lookupflag = INPLOOKUP_WILDCARD | 833 ((thflags & (TH_ACK|TH_SYN)) == TH_SYN ? 834 INPLOOKUP_RLOCKPCB : INPLOOKUP_WLOCKPCB); 835 findpcb: 836 #ifdef INET6 837 if (isipv6 && fwd_tag != NULL) { 838 struct sockaddr_in6 *next_hop6; 839 840 next_hop6 = (struct sockaddr_in6 *)(fwd_tag + 1); 841 /* 842 * Transparently forwarded. Pretend to be the destination. 843 * Already got one like this? 844 */ 845 inp = in6_pcblookup_mbuf(&V_tcbinfo, 846 &ip6->ip6_src, th->th_sport, &ip6->ip6_dst, th->th_dport, 847 lookupflag & ~INPLOOKUP_WILDCARD, m->m_pkthdr.rcvif, m); 848 if (!inp) { 849 /* 850 * It's new. Try to find the ambushing socket. 851 * Because we've rewritten the destination address, 852 * any hardware-generated hash is ignored. 853 */ 854 inp = in6_pcblookup(&V_tcbinfo, &ip6->ip6_src, 855 th->th_sport, &next_hop6->sin6_addr, 856 next_hop6->sin6_port ? ntohs(next_hop6->sin6_port) : 857 th->th_dport, lookupflag, m->m_pkthdr.rcvif); 858 } 859 } else if (isipv6) { 860 inp = in6_pcblookup_mbuf(&V_tcbinfo, &ip6->ip6_src, 861 th->th_sport, &ip6->ip6_dst, th->th_dport, lookupflag, 862 m->m_pkthdr.rcvif, m); 863 } 864 #endif /* INET6 */ 865 #if defined(INET6) && defined(INET) 866 else 867 #endif 868 #ifdef INET 869 if (fwd_tag != NULL) { 870 struct sockaddr_in *next_hop; 871 872 next_hop = (struct sockaddr_in *)(fwd_tag+1); 873 /* 874 * Transparently forwarded. Pretend to be the destination. 875 * already got one like this? 876 */ 877 inp = in_pcblookup_mbuf(&V_tcbinfo, ip->ip_src, th->th_sport, 878 ip->ip_dst, th->th_dport, lookupflag & ~INPLOOKUP_WILDCARD, 879 m->m_pkthdr.rcvif, m); 880 if (!inp) { 881 /* 882 * It's new. Try to find the ambushing socket. 883 * Because we've rewritten the destination address, 884 * any hardware-generated hash is ignored. 885 */ 886 inp = in_pcblookup(&V_tcbinfo, ip->ip_src, 887 th->th_sport, next_hop->sin_addr, 888 next_hop->sin_port ? ntohs(next_hop->sin_port) : 889 th->th_dport, lookupflag, m->m_pkthdr.rcvif); 890 } 891 } else 892 inp = in_pcblookup_mbuf(&V_tcbinfo, ip->ip_src, 893 th->th_sport, ip->ip_dst, th->th_dport, lookupflag, 894 m->m_pkthdr.rcvif, m); 895 #endif /* INET */ 896 897 /* 898 * If the INPCB does not exist then all data in the incoming 899 * segment is discarded and an appropriate RST is sent back. 900 * XXX MRT Send RST using which routing table? 901 */ 902 if (inp == NULL) { 903 if (rstreason != 0) { 904 /* We came here after second (safety) lookup. */ 905 MPASS((lookupflag & INPLOOKUP_WILDCARD) == 0); 906 goto dropwithreset; 907 } 908 /* 909 * Log communication attempts to ports that are not 910 * in use. 911 */ 912 if ((V_tcp_log_in_vain == 1 && (thflags & TH_SYN)) || 913 V_tcp_log_in_vain == 2) { 914 if ((s = tcp_log_vain(NULL, th, (void *)ip, ip6))) 915 log(LOG_INFO, "%s; %s: Connection attempt " 916 "to closed port\n", s, __func__); 917 } 918 /* 919 * When blackholing do not respond with a RST but 920 * completely ignore the segment and drop it. 921 */ 922 if (((V_blackhole == 1 && (thflags & TH_SYN)) || 923 V_blackhole == 2) && (V_blackhole_local || ( 924 #ifdef INET6 925 isipv6 ? !in6_localaddr(&ip6->ip6_src) : 926 #endif 927 #ifdef INET 928 !in_localip(ip->ip_src) 929 #else 930 true 931 #endif 932 ))) 933 goto dropunlock; 934 935 rstreason = BANDLIM_RST_CLOSEDPORT; 936 goto dropwithreset; 937 } 938 INP_LOCK_ASSERT(inp); 939 940 if ((inp->inp_flowtype == M_HASHTYPE_NONE) && 941 !SOLISTENING(inp->inp_socket)) { 942 if (M_HASHTYPE_GET(m) != M_HASHTYPE_NONE) { 943 inp->inp_flowid = m->m_pkthdr.flowid; 944 inp->inp_flowtype = M_HASHTYPE_GET(m); 945 #ifdef RSS 946 } else { 947 /* assign flowid by software RSS hash */ 948 #ifdef INET6 949 if (isipv6) { 950 rss_proto_software_hash_v6(&inp->in6p_faddr, 951 &inp->in6p_laddr, 952 inp->inp_fport, 953 inp->inp_lport, 954 IPPROTO_TCP, 955 &inp->inp_flowid, 956 &inp->inp_flowtype); 957 } else 958 #endif /* INET6 */ 959 { 960 rss_proto_software_hash_v4(inp->inp_faddr, 961 inp->inp_laddr, 962 inp->inp_fport, 963 inp->inp_lport, 964 IPPROTO_TCP, 965 &inp->inp_flowid, 966 &inp->inp_flowtype); 967 } 968 #endif /* RSS */ 969 } 970 } 971 #if defined(IPSEC) || defined(IPSEC_SUPPORT) 972 #ifdef INET6 973 if (isipv6 && IPSEC_ENABLED(ipv6) && 974 IPSEC_CHECK_POLICY(ipv6, m, inp) != 0) { 975 goto dropunlock; 976 } 977 #ifdef INET 978 else 979 #endif 980 #endif /* INET6 */ 981 #ifdef INET 982 if (IPSEC_ENABLED(ipv4) && 983 IPSEC_CHECK_POLICY(ipv4, m, inp) != 0) { 984 goto dropunlock; 985 } 986 #endif /* INET */ 987 #endif /* IPSEC */ 988 989 /* 990 * Check the minimum TTL for socket. 991 */ 992 if (inp->inp_ip_minttl != 0) { 993 #ifdef INET6 994 if (isipv6) { 995 if (inp->inp_ip_minttl > ip6->ip6_hlim) 996 goto dropunlock; 997 } else 998 #endif 999 if (inp->inp_ip_minttl > ip->ip_ttl) 1000 goto dropunlock; 1001 } 1002 1003 tp = intotcpcb(inp); 1004 switch (tp->t_state) { 1005 case TCPS_TIME_WAIT: 1006 /* 1007 * A previous connection in TIMEWAIT state is supposed to catch 1008 * stray or duplicate segments arriving late. If this segment 1009 * was a legitimate new connection attempt, the old INPCB gets 1010 * removed and we can try again to find a listening socket. 1011 */ 1012 tcp_dooptions(&to, optp, optlen, 1013 (thflags & TH_SYN) ? TO_SYN : 0); 1014 /* 1015 * tcp_twcheck unlocks the inp always, and frees the m if fails. 1016 */ 1017 if (tcp_twcheck(inp, &to, th, m, tlen)) 1018 goto findpcb; 1019 return (IPPROTO_DONE); 1020 case TCPS_CLOSED: 1021 /* 1022 * The TCPCB may no longer exist if the connection is winding 1023 * down or it is in the CLOSED state. Either way we drop the 1024 * segment and send an appropriate response. 1025 */ 1026 rstreason = BANDLIM_RST_CLOSEDPORT; 1027 goto dropwithreset; 1028 } 1029 1030 if ((tp->t_port != port) && (tp->t_state > TCPS_LISTEN)) { 1031 rstreason = BANDLIM_RST_CLOSEDPORT; 1032 goto dropwithreset; 1033 } 1034 1035 #ifdef TCP_OFFLOAD 1036 if (tp->t_flags & TF_TOE) { 1037 tcp_offload_input(tp, m); 1038 m = NULL; /* consumed by the TOE driver */ 1039 goto dropunlock; 1040 } 1041 #endif 1042 1043 #ifdef MAC 1044 if (mac_inpcb_check_deliver(inp, m)) 1045 goto dropunlock; 1046 #endif 1047 so = inp->inp_socket; 1048 KASSERT(so != NULL, ("%s: so == NULL", __func__)); 1049 /* 1050 * When the socket is accepting connections (the INPCB is in LISTEN 1051 * state) we look into the SYN cache if this is a new connection 1052 * attempt or the completion of a previous one. 1053 */ 1054 KASSERT(tp->t_state == TCPS_LISTEN || !SOLISTENING(so), 1055 ("%s: so accepting but tp %p not listening", __func__, tp)); 1056 if (tp->t_state == TCPS_LISTEN && SOLISTENING(so)) { 1057 struct in_conninfo inc; 1058 1059 bzero(&inc, sizeof(inc)); 1060 #ifdef INET6 1061 if (isipv6) { 1062 inc.inc_flags |= INC_ISIPV6; 1063 if (inp->inp_inc.inc_flags & INC_IPV6MINMTU) 1064 inc.inc_flags |= INC_IPV6MINMTU; 1065 inc.inc6_faddr = ip6->ip6_src; 1066 inc.inc6_laddr = ip6->ip6_dst; 1067 } else 1068 #endif 1069 { 1070 inc.inc_faddr = ip->ip_src; 1071 inc.inc_laddr = ip->ip_dst; 1072 } 1073 inc.inc_fport = th->th_sport; 1074 inc.inc_lport = th->th_dport; 1075 inc.inc_fibnum = so->so_fibnum; 1076 1077 /* 1078 * Check for an existing connection attempt in syncache if 1079 * the flag is only ACK. A successful lookup creates a new 1080 * socket appended to the listen queue in SYN_RECEIVED state. 1081 */ 1082 if ((thflags & (TH_RST|TH_ACK|TH_SYN)) == TH_ACK) { 1083 /* 1084 * Parse the TCP options here because 1085 * syncookies need access to the reflected 1086 * timestamp. 1087 */ 1088 tcp_dooptions(&to, optp, optlen, 0); 1089 /* 1090 * NB: syncache_expand() doesn't unlock inp. 1091 */ 1092 rstreason = syncache_expand(&inc, &to, th, &so, m, port); 1093 if (rstreason < 0) { 1094 /* 1095 * A failing TCP MD5 signature comparison 1096 * must result in the segment being dropped 1097 * and must not produce any response back 1098 * to the sender. 1099 */ 1100 goto dropunlock; 1101 } else if (rstreason == 0) { 1102 /* 1103 * No syncache entry, or ACK was not for our 1104 * SYN/ACK. Do our protection against double 1105 * ACK. If peer sent us 2 ACKs, then for the 1106 * first one syncache_expand() successfully 1107 * converted syncache entry into a socket, 1108 * while we were waiting on the inpcb lock. We 1109 * don't want to sent RST for the second ACK, 1110 * so we perform second lookup without wildcard 1111 * match, hoping to find the new socket. If 1112 * the ACK is stray indeed, rstreason would 1113 * hint the above code that the lookup was a 1114 * second attempt. 1115 * 1116 * NB: syncache did its own logging 1117 * of the failure cause. 1118 */ 1119 INP_WUNLOCK(inp); 1120 rstreason = BANDLIM_RST_OPENPORT; 1121 lookupflag &= ~INPLOOKUP_WILDCARD; 1122 goto findpcb; 1123 } 1124 tfo_socket_result: 1125 if (so == NULL) { 1126 /* 1127 * We completed the 3-way handshake 1128 * but could not allocate a socket 1129 * either due to memory shortage, 1130 * listen queue length limits or 1131 * global socket limits. Send RST 1132 * or wait and have the remote end 1133 * retransmit the ACK for another 1134 * try. 1135 */ 1136 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1137 log(LOG_DEBUG, "%s; %s: Listen socket: " 1138 "Socket allocation failed due to " 1139 "limits or memory shortage, %s\n", 1140 s, __func__, 1141 V_tcp_sc_rst_sock_fail ? 1142 "sending RST" : "try again"); 1143 if (V_tcp_sc_rst_sock_fail) { 1144 rstreason = BANDLIM_UNLIMITED; 1145 goto dropwithreset; 1146 } else 1147 goto dropunlock; 1148 } 1149 /* 1150 * Socket is created in state SYN_RECEIVED. 1151 * Unlock the listen socket, lock the newly 1152 * created socket and update the tp variable. 1153 * If we came here via jump to tfo_socket_result, 1154 * then listening socket is read-locked. 1155 */ 1156 INP_UNLOCK(inp); /* listen socket */ 1157 inp = sotoinpcb(so); 1158 /* 1159 * New connection inpcb is already locked by 1160 * syncache_expand(). 1161 */ 1162 INP_WLOCK_ASSERT(inp); 1163 tp = intotcpcb(inp); 1164 KASSERT(tp->t_state == TCPS_SYN_RECEIVED, 1165 ("%s: ", __func__)); 1166 /* 1167 * Process the segment and the data it 1168 * contains. tcp_do_segment() consumes 1169 * the mbuf chain and unlocks the inpcb. 1170 */ 1171 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1172 tp->t_fb->tfb_tcp_do_segment(tp, m, th, drop_hdrlen, 1173 tlen, iptos); 1174 return (IPPROTO_DONE); 1175 } 1176 /* 1177 * Segment flag validation for new connection attempts: 1178 * 1179 * Our (SYN|ACK) response was rejected. 1180 * Check with syncache and remove entry to prevent 1181 * retransmits. 1182 * 1183 * NB: syncache_chkrst does its own logging of failure 1184 * causes. 1185 */ 1186 if (thflags & TH_RST) { 1187 syncache_chkrst(&inc, th, m, port); 1188 goto dropunlock; 1189 } 1190 /* 1191 * We can't do anything without SYN. 1192 */ 1193 if ((thflags & TH_SYN) == 0) { 1194 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1195 log(LOG_DEBUG, "%s; %s: Listen socket: " 1196 "SYN is missing, segment ignored\n", 1197 s, __func__); 1198 TCPSTAT_INC(tcps_badsyn); 1199 goto dropunlock; 1200 } 1201 /* 1202 * (SYN|ACK) is bogus on a listen socket. 1203 */ 1204 if (thflags & TH_ACK) { 1205 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1206 log(LOG_DEBUG, "%s; %s: Listen socket: " 1207 "SYN|ACK invalid, segment rejected\n", 1208 s, __func__); 1209 syncache_badack(&inc, port); /* XXX: Not needed! */ 1210 TCPSTAT_INC(tcps_badsyn); 1211 rstreason = BANDLIM_RST_OPENPORT; 1212 goto dropwithreset; 1213 } 1214 /* 1215 * If the drop_synfin option is enabled, drop all 1216 * segments with both the SYN and FIN bits set. 1217 * This prevents e.g. nmap from identifying the 1218 * TCP/IP stack. 1219 * XXX: Poor reasoning. nmap has other methods 1220 * and is constantly refining its stack detection 1221 * strategies. 1222 * XXX: This is a violation of the TCP specification 1223 * and was used by RFC1644. 1224 */ 1225 if ((thflags & TH_FIN) && V_drop_synfin) { 1226 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1227 log(LOG_DEBUG, "%s; %s: Listen socket: " 1228 "SYN|FIN segment ignored (based on " 1229 "sysctl setting)\n", s, __func__); 1230 TCPSTAT_INC(tcps_badsyn); 1231 goto dropunlock; 1232 } 1233 /* 1234 * Segment's flags are (SYN) or (SYN|FIN). 1235 * 1236 * TH_PUSH, TH_URG, TH_ECE, TH_CWR are ignored 1237 * as they do not affect the state of the TCP FSM. 1238 * The data pointed to by TH_URG and th_urp is ignored. 1239 */ 1240 KASSERT((thflags & (TH_RST|TH_ACK)) == 0, 1241 ("%s: Listen socket: TH_RST or TH_ACK set", __func__)); 1242 KASSERT(thflags & (TH_SYN), 1243 ("%s: Listen socket: TH_SYN not set", __func__)); 1244 INP_RLOCK_ASSERT(inp); 1245 #ifdef INET6 1246 /* 1247 * If deprecated address is forbidden, 1248 * we do not accept SYN to deprecated interface 1249 * address to prevent any new inbound connection from 1250 * getting established. 1251 * When we do not accept SYN, we send a TCP RST, 1252 * with deprecated source address (instead of dropping 1253 * it). We compromise it as it is much better for peer 1254 * to send a RST, and RST will be the final packet 1255 * for the exchange. 1256 * 1257 * If we do not forbid deprecated addresses, we accept 1258 * the SYN packet. RFC2462 does not suggest dropping 1259 * SYN in this case. 1260 * If we decipher RFC2462 5.5.4, it says like this: 1261 * 1. use of deprecated addr with existing 1262 * communication is okay - "SHOULD continue to be 1263 * used" 1264 * 2. use of it with new communication: 1265 * (2a) "SHOULD NOT be used if alternate address 1266 * with sufficient scope is available" 1267 * (2b) nothing mentioned otherwise. 1268 * Here we fall into (2b) case as we have no choice in 1269 * our source address selection - we must obey the peer. 1270 * 1271 * The wording in RFC2462 is confusing, and there are 1272 * multiple description text for deprecated address 1273 * handling - worse, they are not exactly the same. 1274 * I believe 5.5.4 is the best one, so we follow 5.5.4. 1275 */ 1276 if (isipv6 && !V_ip6_use_deprecated) { 1277 struct in6_ifaddr *ia6; 1278 1279 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false); 1280 if (ia6 != NULL && 1281 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) { 1282 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1283 log(LOG_DEBUG, "%s; %s: Listen socket: " 1284 "Connection attempt to deprecated " 1285 "IPv6 address rejected\n", 1286 s, __func__); 1287 rstreason = BANDLIM_RST_OPENPORT; 1288 goto dropwithreset; 1289 } 1290 } 1291 #endif /* INET6 */ 1292 /* 1293 * Basic sanity checks on incoming SYN requests: 1294 * Don't respond if the destination is a link layer 1295 * broadcast according to RFC1122 4.2.3.10, p. 104. 1296 * If it is from this socket it must be forged. 1297 * Don't respond if the source or destination is a 1298 * global or subnet broad- or multicast address. 1299 * Note that it is quite possible to receive unicast 1300 * link-layer packets with a broadcast IP address. Use 1301 * in_broadcast() to find them. 1302 */ 1303 if (m->m_flags & (M_BCAST|M_MCAST)) { 1304 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1305 log(LOG_DEBUG, "%s; %s: Listen socket: " 1306 "Connection attempt from broad- or multicast " 1307 "link layer address ignored\n", s, __func__); 1308 goto dropunlock; 1309 } 1310 #ifdef INET6 1311 if (isipv6) { 1312 if (th->th_dport == th->th_sport && 1313 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &ip6->ip6_src)) { 1314 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1315 log(LOG_DEBUG, "%s; %s: Listen socket: " 1316 "Connection attempt to/from self " 1317 "ignored\n", s, __func__); 1318 goto dropunlock; 1319 } 1320 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 1321 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) { 1322 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1323 log(LOG_DEBUG, "%s; %s: Listen socket: " 1324 "Connection attempt from/to multicast " 1325 "address ignored\n", s, __func__); 1326 goto dropunlock; 1327 } 1328 } 1329 #endif 1330 #if defined(INET) && defined(INET6) 1331 else 1332 #endif 1333 #ifdef INET 1334 { 1335 if (th->th_dport == th->th_sport && 1336 ip->ip_dst.s_addr == ip->ip_src.s_addr) { 1337 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1338 log(LOG_DEBUG, "%s; %s: Listen socket: " 1339 "Connection attempt from/to self " 1340 "ignored\n", s, __func__); 1341 goto dropunlock; 1342 } 1343 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 1344 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 1345 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || 1346 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) { 1347 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1348 log(LOG_DEBUG, "%s; %s: Listen socket: " 1349 "Connection attempt from/to broad- " 1350 "or multicast address ignored\n", 1351 s, __func__); 1352 goto dropunlock; 1353 } 1354 } 1355 #endif 1356 /* 1357 * SYN appears to be valid. Create compressed TCP state 1358 * for syncache. 1359 */ 1360 TCP_PROBE3(debug__input, tp, th, m); 1361 tcp_dooptions(&to, optp, optlen, TO_SYN); 1362 if ((so = syncache_add(&inc, &to, th, inp, so, m, NULL, NULL, 1363 iptos, port)) != NULL) 1364 goto tfo_socket_result; 1365 1366 /* 1367 * Entry added to syncache and mbuf consumed. 1368 * Only the listen socket is unlocked by syncache_add(). 1369 */ 1370 return (IPPROTO_DONE); 1371 } else if (tp->t_state == TCPS_LISTEN) { 1372 /* 1373 * When a listen socket is torn down the SO_ACCEPTCONN 1374 * flag is removed first while connections are drained 1375 * from the accept queue in a unlock/lock cycle of the 1376 * ACCEPT_LOCK, opening a race condition allowing a SYN 1377 * attempt go through unhandled. 1378 */ 1379 goto dropunlock; 1380 } 1381 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 1382 if (tp->t_flags & TF_SIGNATURE) { 1383 tcp_dooptions(&to, optp, optlen, thflags); 1384 if ((to.to_flags & TOF_SIGNATURE) == 0) { 1385 TCPSTAT_INC(tcps_sig_err_nosigopt); 1386 goto dropunlock; 1387 } 1388 if (!TCPMD5_ENABLED() || 1389 TCPMD5_INPUT(m, th, to.to_signature) != 0) 1390 goto dropunlock; 1391 } 1392 #endif 1393 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1394 1395 /* 1396 * Segment belongs to a connection in SYN_SENT, ESTABLISHED or later 1397 * state. tcp_do_segment() always consumes the mbuf chain, unlocks 1398 * the inpcb, and unlocks pcbinfo. 1399 * 1400 * XXXGL: in case of a pure SYN arriving on existing connection 1401 * TCP stacks won't need to modify the PCB, they would either drop 1402 * the segment silently, or send a challenge ACK. However, we try 1403 * to upgrade the lock, because calling convention for stacks is 1404 * write-lock on PCB. If upgrade fails, drop the SYN. 1405 */ 1406 if ((lookupflag & INPLOOKUP_RLOCKPCB) && INP_TRY_UPGRADE(inp) == 0) 1407 goto dropunlock; 1408 1409 tp->t_fb->tfb_tcp_do_segment(tp, m, th, drop_hdrlen, tlen, iptos); 1410 return (IPPROTO_DONE); 1411 1412 dropwithreset: 1413 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1414 1415 if (inp != NULL) { 1416 tcp_dropwithreset(m, th, tp, tlen, rstreason); 1417 INP_UNLOCK(inp); 1418 } else 1419 tcp_dropwithreset(m, th, NULL, tlen, rstreason); 1420 m = NULL; /* mbuf chain got consumed. */ 1421 goto drop; 1422 1423 dropunlock: 1424 if (m != NULL) 1425 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1426 1427 if (inp != NULL) 1428 INP_UNLOCK(inp); 1429 1430 drop: 1431 if (s != NULL) 1432 free(s, M_TCPLOG); 1433 if (m != NULL) 1434 m_freem(m); 1435 return (IPPROTO_DONE); 1436 } 1437 1438 /* 1439 * Automatic sizing of receive socket buffer. Often the send 1440 * buffer size is not optimally adjusted to the actual network 1441 * conditions at hand (delay bandwidth product). Setting the 1442 * buffer size too small limits throughput on links with high 1443 * bandwidth and high delay (eg. trans-continental/oceanic links). 1444 * 1445 * On the receive side the socket buffer memory is only rarely 1446 * used to any significant extent. This allows us to be much 1447 * more aggressive in scaling the receive socket buffer. For 1448 * the case that the buffer space is actually used to a large 1449 * extent and we run out of kernel memory we can simply drop 1450 * the new segments; TCP on the sender will just retransmit it 1451 * later. Setting the buffer size too big may only consume too 1452 * much kernel memory if the application doesn't read() from 1453 * the socket or packet loss or reordering makes use of the 1454 * reassembly queue. 1455 * 1456 * The criteria to step up the receive buffer one notch are: 1457 * 1. Application has not set receive buffer size with 1458 * SO_RCVBUF. Setting SO_RCVBUF clears SB_AUTOSIZE. 1459 * 2. the number of bytes received during 1/2 of an sRTT 1460 * is at least 3/8 of the current socket buffer size. 1461 * 3. receive buffer size has not hit maximal automatic size; 1462 * 1463 * If all of the criteria are met we increaset the socket buffer 1464 * by a 1/2 (bounded by the max). This allows us to keep ahead 1465 * of slow-start but also makes it so our peer never gets limited 1466 * by our rwnd which we then open up causing a burst. 1467 * 1468 * This algorithm does two steps per RTT at most and only if 1469 * we receive a bulk stream w/o packet losses or reorderings. 1470 * Shrinking the buffer during idle times is not necessary as 1471 * it doesn't consume any memory when idle. 1472 * 1473 * TODO: Only step up if the application is actually serving 1474 * the buffer to better manage the socket buffer resources. 1475 */ 1476 int 1477 tcp_autorcvbuf(struct mbuf *m, struct tcphdr *th, struct socket *so, 1478 struct tcpcb *tp, int tlen) 1479 { 1480 int newsize = 0; 1481 1482 if (V_tcp_do_autorcvbuf && (so->so_rcv.sb_flags & SB_AUTOSIZE) && 1483 tp->t_srtt != 0 && tp->rfbuf_ts != 0 && 1484 TCP_TS_TO_TICKS(tcp_ts_getticks() - tp->rfbuf_ts) > 1485 ((tp->t_srtt >> TCP_RTT_SHIFT)/2)) { 1486 if (tp->rfbuf_cnt > ((so->so_rcv.sb_hiwat / 2)/ 4 * 3) && 1487 so->so_rcv.sb_hiwat < V_tcp_autorcvbuf_max) { 1488 newsize = min((so->so_rcv.sb_hiwat + (so->so_rcv.sb_hiwat/2)), V_tcp_autorcvbuf_max); 1489 } 1490 TCP_PROBE6(receive__autoresize, NULL, tp, m, tp, th, newsize); 1491 1492 /* Start over with next RTT. */ 1493 tp->rfbuf_ts = 0; 1494 tp->rfbuf_cnt = 0; 1495 } else { 1496 tp->rfbuf_cnt += tlen; /* add up */ 1497 } 1498 return (newsize); 1499 } 1500 1501 int 1502 tcp_input(struct mbuf **mp, int *offp, int proto) 1503 { 1504 return(tcp_input_with_port(mp, offp, proto, 0)); 1505 } 1506 1507 static void 1508 tcp_handle_wakeup(struct tcpcb *tp) 1509 { 1510 1511 INP_WLOCK_ASSERT(tptoinpcb(tp)); 1512 1513 if (tp->t_flags & TF_WAKESOR) { 1514 struct socket *so = tptosocket(tp); 1515 1516 tp->t_flags &= ~TF_WAKESOR; 1517 SOCKBUF_LOCK_ASSERT(&so->so_rcv); 1518 sorwakeup_locked(so); 1519 } 1520 } 1521 1522 void 1523 tcp_do_segment(struct tcpcb *tp, struct mbuf *m, struct tcphdr *th, 1524 int drop_hdrlen, int tlen, uint8_t iptos) 1525 { 1526 uint16_t thflags; 1527 int acked, ourfinisacked, needoutput = 0; 1528 sackstatus_t sack_changed; 1529 int rstreason, todrop, win, incforsyn = 0; 1530 uint32_t tiwin; 1531 uint16_t nsegs; 1532 char *s; 1533 struct inpcb *inp = tptoinpcb(tp); 1534 struct socket *so = tptosocket(tp); 1535 struct in_conninfo *inc = &inp->inp_inc; 1536 struct mbuf *mfree; 1537 struct tcpopt to; 1538 int tfo_syn; 1539 u_int maxseg = 0; 1540 1541 thflags = tcp_get_flags(th); 1542 tp->sackhint.last_sack_ack = 0; 1543 sack_changed = SACK_NOCHANGE; 1544 nsegs = max(1, m->m_pkthdr.lro_nsegs); 1545 1546 NET_EPOCH_ASSERT(); 1547 INP_WLOCK_ASSERT(inp); 1548 KASSERT(tp->t_state > TCPS_LISTEN, ("%s: TCPS_LISTEN", 1549 __func__)); 1550 KASSERT(tp->t_state != TCPS_TIME_WAIT, ("%s: TCPS_TIME_WAIT", 1551 __func__)); 1552 1553 #ifdef TCPPCAP 1554 /* Save segment, if requested. */ 1555 tcp_pcap_add(th, m, &(tp->t_inpkts)); 1556 #endif 1557 TCP_LOG_EVENT(tp, th, &so->so_rcv, &so->so_snd, TCP_LOG_IN, 0, 1558 tlen, NULL, true); 1559 1560 if ((thflags & TH_SYN) && (thflags & TH_FIN) && V_drop_synfin) { 1561 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1562 log(LOG_DEBUG, "%s; %s: " 1563 "SYN|FIN segment ignored (based on " 1564 "sysctl setting)\n", s, __func__); 1565 free(s, M_TCPLOG); 1566 } 1567 goto drop; 1568 } 1569 1570 /* 1571 * If a segment with the ACK-bit set arrives in the SYN-SENT state 1572 * check SEQ.ACK first. 1573 */ 1574 if ((tp->t_state == TCPS_SYN_SENT) && (thflags & TH_ACK) && 1575 (SEQ_LEQ(th->th_ack, tp->iss) || SEQ_GT(th->th_ack, tp->snd_max))) { 1576 rstreason = BANDLIM_UNLIMITED; 1577 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 1578 goto dropwithreset; 1579 } 1580 1581 /* 1582 * Segment received on connection. 1583 * Reset idle time and keep-alive timer. 1584 * XXX: This should be done after segment 1585 * validation to ignore broken/spoofed segs. 1586 */ 1587 if (tp->t_idle_reduce && 1588 (tp->snd_max == tp->snd_una) && 1589 ((ticks - tp->t_rcvtime) >= tp->t_rxtcur)) 1590 cc_after_idle(tp); 1591 tp->t_rcvtime = ticks; 1592 1593 if (thflags & TH_FIN) 1594 tcp_log_end_status(tp, TCP_EI_STATUS_CLIENT_FIN); 1595 /* 1596 * Scale up the window into a 32-bit value. 1597 * For the SYN_SENT state the scale is zero. 1598 */ 1599 tiwin = th->th_win << tp->snd_scale; 1600 #ifdef STATS 1601 stats_voi_update_abs_ulong(tp->t_stats, VOI_TCP_FRWIN, tiwin); 1602 #endif 1603 1604 /* 1605 * TCP ECN processing. 1606 */ 1607 if (tcp_ecn_input_segment(tp, thflags, tlen, 1608 tcp_packets_this_ack(tp, th->th_ack), 1609 iptos)) 1610 cc_cong_signal(tp, th, CC_ECN); 1611 1612 /* 1613 * Parse options on any incoming segment. 1614 */ 1615 tcp_dooptions(&to, (u_char *)(th + 1), 1616 (th->th_off << 2) - sizeof(struct tcphdr), 1617 (thflags & TH_SYN) ? TO_SYN : 0); 1618 1619 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 1620 if ((tp->t_flags & TF_SIGNATURE) != 0 && 1621 (to.to_flags & TOF_SIGNATURE) == 0) { 1622 TCPSTAT_INC(tcps_sig_err_sigopt); 1623 /* XXX: should drop? */ 1624 } 1625 #endif 1626 /* 1627 * If echoed timestamp is later than the current time, 1628 * fall back to non RFC1323 RTT calculation. Normalize 1629 * timestamp if syncookies were used when this connection 1630 * was established. 1631 */ 1632 if ((to.to_flags & TOF_TS) && (to.to_tsecr != 0)) { 1633 to.to_tsecr -= tp->ts_offset; 1634 if (TSTMP_GT(to.to_tsecr, tcp_ts_getticks())) { 1635 to.to_tsecr = 0; 1636 } else if (tp->t_rxtshift == 1 && 1637 tp->t_flags & TF_PREVVALID && 1638 tp->t_badrxtwin != 0 && 1639 TSTMP_LT(to.to_tsecr, tp->t_badrxtwin)) { 1640 cc_cong_signal(tp, th, CC_RTO_ERR); 1641 } 1642 } 1643 /* 1644 * Process options only when we get SYN/ACK back. The SYN case 1645 * for incoming connections is handled in tcp_syncache. 1646 * According to RFC1323 the window field in a SYN (i.e., a <SYN> 1647 * or <SYN,ACK>) segment itself is never scaled. 1648 * XXX this is traditional behavior, may need to be cleaned up. 1649 */ 1650 if (tp->t_state == TCPS_SYN_SENT && (thflags & TH_SYN)) { 1651 /* Handle parallel SYN for ECN */ 1652 tcp_ecn_input_parallel_syn(tp, thflags, iptos); 1653 if ((to.to_flags & TOF_SCALE) && 1654 (tp->t_flags & TF_REQ_SCALE) && 1655 !(tp->t_flags & TF_NOOPT)) { 1656 tp->t_flags |= TF_RCVD_SCALE; 1657 tp->snd_scale = to.to_wscale; 1658 } else { 1659 tp->t_flags &= ~TF_REQ_SCALE; 1660 } 1661 /* 1662 * Initial send window. It will be updated with 1663 * the next incoming segment to the scaled value. 1664 */ 1665 tp->snd_wnd = th->th_win; 1666 if ((to.to_flags & TOF_TS) && 1667 (tp->t_flags & TF_REQ_TSTMP) && 1668 !(tp->t_flags & TF_NOOPT)) { 1669 tp->t_flags |= TF_RCVD_TSTMP; 1670 tp->ts_recent = to.to_tsval; 1671 tp->ts_recent_age = tcp_ts_getticks(); 1672 } else { 1673 tp->t_flags &= ~TF_REQ_TSTMP; 1674 } 1675 if (to.to_flags & TOF_MSS) { 1676 tcp_mss(tp, to.to_mss); 1677 } 1678 if ((tp->t_flags & TF_SACK_PERMIT) && 1679 (!(to.to_flags & TOF_SACKPERM) || 1680 (tp->t_flags & TF_NOOPT))) { 1681 tp->t_flags &= ~TF_SACK_PERMIT; 1682 } 1683 if (IS_FASTOPEN(tp->t_flags)) { 1684 if ((to.to_flags & TOF_FASTOPEN) && 1685 !(tp->t_flags & TF_NOOPT)) { 1686 uint16_t mss; 1687 1688 if (to.to_flags & TOF_MSS) { 1689 mss = to.to_mss; 1690 } else { 1691 if ((inp->inp_vflag & INP_IPV6) != 0) { 1692 mss = TCP6_MSS; 1693 } else { 1694 mss = TCP_MSS; 1695 } 1696 } 1697 tcp_fastopen_update_cache(tp, mss, 1698 to.to_tfo_len, to.to_tfo_cookie); 1699 } else { 1700 tcp_fastopen_disable_path(tp); 1701 } 1702 } 1703 } 1704 1705 /* 1706 * If timestamps were negotiated during SYN/ACK and a 1707 * segment without a timestamp is received, silently drop 1708 * the segment, unless it is a RST segment or missing timestamps are 1709 * tolerated. 1710 * See section 3.2 of RFC 7323. 1711 */ 1712 if ((tp->t_flags & TF_RCVD_TSTMP) && !(to.to_flags & TOF_TS)) { 1713 if (((thflags & TH_RST) != 0) || V_tcp_tolerate_missing_ts) { 1714 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1715 log(LOG_DEBUG, "%s; %s: Timestamp missing, " 1716 "segment processed normally\n", 1717 s, __func__); 1718 free(s, M_TCPLOG); 1719 } 1720 } else { 1721 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1722 log(LOG_DEBUG, "%s; %s: Timestamp missing, " 1723 "segment silently dropped\n", s, __func__); 1724 free(s, M_TCPLOG); 1725 } 1726 goto drop; 1727 } 1728 } 1729 /* 1730 * If timestamps were not negotiated during SYN/ACK and a 1731 * segment with a timestamp is received, ignore the 1732 * timestamp and process the packet normally. 1733 * See section 3.2 of RFC 7323. 1734 */ 1735 if (!(tp->t_flags & TF_RCVD_TSTMP) && (to.to_flags & TOF_TS)) { 1736 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1737 log(LOG_DEBUG, "%s; %s: Timestamp not expected, " 1738 "segment processed normally\n", s, __func__); 1739 free(s, M_TCPLOG); 1740 } 1741 } 1742 1743 /* 1744 * Header prediction: check for the two common cases 1745 * of a uni-directional data xfer. If the packet has 1746 * no control flags, is in-sequence, the window didn't 1747 * change and we're not retransmitting, it's a 1748 * candidate. If the length is zero and the ack moved 1749 * forward, we're the sender side of the xfer. Just 1750 * free the data acked & wake any higher level process 1751 * that was blocked waiting for space. If the length 1752 * is non-zero and the ack didn't move, we're the 1753 * receiver side. If we're getting packets in-order 1754 * (the reassembly queue is empty), add the data to 1755 * the socket buffer and note that we need a delayed ack. 1756 * Make sure that the hidden state-flags are also off. 1757 * Since we check for TCPS_ESTABLISHED first, it can only 1758 * be TH_NEEDSYN. 1759 */ 1760 if (tp->t_state == TCPS_ESTABLISHED && 1761 th->th_seq == tp->rcv_nxt && 1762 (thflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK && 1763 tp->snd_nxt == tp->snd_max && 1764 tiwin && tiwin == tp->snd_wnd && 1765 ((tp->t_flags & (TF_NEEDSYN|TF_NEEDFIN)) == 0) && 1766 SEGQ_EMPTY(tp) && 1767 ((to.to_flags & TOF_TS) == 0 || 1768 TSTMP_GEQ(to.to_tsval, tp->ts_recent)) ) { 1769 /* 1770 * If last ACK falls within this segment's sequence numbers, 1771 * record the timestamp. 1772 * NOTE that the test is modified according to the latest 1773 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 1774 */ 1775 if ((to.to_flags & TOF_TS) != 0 && 1776 SEQ_LEQ(th->th_seq, tp->last_ack_sent)) { 1777 tp->ts_recent_age = tcp_ts_getticks(); 1778 tp->ts_recent = to.to_tsval; 1779 } 1780 1781 if (tlen == 0) { 1782 if (SEQ_GT(th->th_ack, tp->snd_una) && 1783 SEQ_LEQ(th->th_ack, tp->snd_max) && 1784 !IN_RECOVERY(tp->t_flags) && 1785 (to.to_flags & TOF_SACK) == 0 && 1786 TAILQ_EMPTY(&tp->snd_holes)) { 1787 /* 1788 * This is a pure ack for outstanding data. 1789 */ 1790 TCPSTAT_INC(tcps_predack); 1791 1792 /* 1793 * "bad retransmit" recovery without timestamps. 1794 */ 1795 if ((to.to_flags & TOF_TS) == 0 && 1796 tp->t_rxtshift == 1 && 1797 tp->t_flags & TF_PREVVALID && 1798 tp->t_badrxtwin != 0 && 1799 TSTMP_LT(ticks, tp->t_badrxtwin)) { 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 TCP_PROBE3(debug__input, tp, th, m); 1869 /* 1870 * Clear t_acktime if remote side has ACKd 1871 * all data in the socket buffer. 1872 * Otherwise, update t_acktime if we received 1873 * a sufficiently large ACK. 1874 */ 1875 if (sbavail(&so->so_snd) == 0) 1876 tp->t_acktime = 0; 1877 else if (acked > 1) 1878 tp->t_acktime = ticks; 1879 if (tp->snd_una == tp->snd_max) 1880 tcp_timer_activate(tp, TT_REXMT, 0); 1881 else if (!tcp_timer_active(tp, TT_PERSIST)) 1882 tcp_timer_activate(tp, TT_REXMT, 1883 TP_RXTCUR(tp)); 1884 sowwakeup(so); 1885 /* 1886 * Only call tcp_output when there 1887 * is new data available to be sent 1888 * or we need to send an ACK. 1889 */ 1890 if ((tp->t_flags & TF_ACKNOW) || 1891 (sbavail(&so->so_snd) >= 1892 SEQ_SUB(tp->snd_max, tp->snd_una))) { 1893 (void) tcp_output(tp); 1894 } 1895 goto check_delack; 1896 } 1897 } else if (th->th_ack == tp->snd_una && 1898 tlen <= sbspace(&so->so_rcv)) { 1899 int newsize = 0; /* automatic sockbuf scaling */ 1900 1901 /* 1902 * This is a pure, in-sequence data packet with 1903 * nothing on the reassembly queue and we have enough 1904 * buffer space to take it. 1905 */ 1906 /* Clean receiver SACK report if present */ 1907 if ((tp->t_flags & TF_SACK_PERMIT) && tp->rcv_numsacks) 1908 tcp_clean_sackreport(tp); 1909 TCPSTAT_INC(tcps_preddat); 1910 tp->rcv_nxt += tlen; 1911 if (tlen && 1912 ((tp->t_flags2 & TF2_FBYTES_COMPLETE) == 0) && 1913 (tp->t_fbyte_in == 0)) { 1914 tp->t_fbyte_in = ticks; 1915 if (tp->t_fbyte_in == 0) 1916 tp->t_fbyte_in = 1; 1917 if (tp->t_fbyte_out && tp->t_fbyte_in) 1918 tp->t_flags2 |= TF2_FBYTES_COMPLETE; 1919 } 1920 /* 1921 * Pull snd_wl1 up to prevent seq wrap relative to 1922 * th_seq. 1923 */ 1924 tp->snd_wl1 = th->th_seq; 1925 /* 1926 * Pull rcv_up up to prevent seq wrap relative to 1927 * rcv_nxt. 1928 */ 1929 tp->rcv_up = tp->rcv_nxt; 1930 TCPSTAT_ADD(tcps_rcvpack, nsegs); 1931 TCPSTAT_ADD(tcps_rcvbyte, tlen); 1932 TCP_PROBE3(debug__input, tp, th, m); 1933 1934 newsize = tcp_autorcvbuf(m, th, so, tp, tlen); 1935 1936 /* Add data to socket buffer. */ 1937 SOCKBUF_LOCK(&so->so_rcv); 1938 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 1939 m_freem(m); 1940 } else { 1941 /* 1942 * Set new socket buffer size. 1943 * Give up when limit is reached. 1944 */ 1945 if (newsize) 1946 if (!sbreserve_locked(so, SO_RCV, 1947 newsize, NULL)) 1948 so->so_rcv.sb_flags &= ~SB_AUTOSIZE; 1949 m_adj(m, drop_hdrlen); /* delayed header drop */ 1950 sbappendstream_locked(&so->so_rcv, m, 0); 1951 } 1952 /* NB: sorwakeup_locked() does an implicit unlock. */ 1953 sorwakeup_locked(so); 1954 if (DELAY_ACK(tp, tlen)) { 1955 tp->t_flags |= TF_DELACK; 1956 } else { 1957 tp->t_flags |= TF_ACKNOW; 1958 tcp_output(tp); 1959 } 1960 goto check_delack; 1961 } 1962 } 1963 1964 /* 1965 * Calculate amount of space in receive window, 1966 * and then do TCP input processing. 1967 * Receive window is amount of space in rcv queue, 1968 * but not less than advertised window. 1969 */ 1970 win = sbspace(&so->so_rcv); 1971 if (win < 0) 1972 win = 0; 1973 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 1974 1975 switch (tp->t_state) { 1976 /* 1977 * If the state is SYN_RECEIVED: 1978 * if seg contains an ACK, but not for our SYN/ACK, send a RST. 1979 */ 1980 case TCPS_SYN_RECEIVED: 1981 if (thflags & TH_RST) { 1982 /* Handle RST segments later. */ 1983 break; 1984 } 1985 if ((thflags & TH_ACK) && 1986 (SEQ_LEQ(th->th_ack, tp->snd_una) || 1987 SEQ_GT(th->th_ack, tp->snd_max))) { 1988 rstreason = BANDLIM_RST_OPENPORT; 1989 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 1990 goto dropwithreset; 1991 } 1992 if (IS_FASTOPEN(tp->t_flags)) { 1993 /* 1994 * When a TFO connection is in SYN_RECEIVED, the 1995 * only valid packets are the initial SYN, a 1996 * retransmit/copy of the initial SYN (possibly with 1997 * a subset of the original data), a valid ACK, a 1998 * FIN, or a RST. 1999 */ 2000 if ((thflags & (TH_SYN|TH_ACK)) == (TH_SYN|TH_ACK)) { 2001 rstreason = BANDLIM_RST_OPENPORT; 2002 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 2003 goto dropwithreset; 2004 } else if (thflags & TH_SYN) { 2005 /* non-initial SYN is ignored */ 2006 if ((tcp_timer_active(tp, TT_DELACK) || 2007 tcp_timer_active(tp, TT_REXMT))) 2008 goto drop; 2009 } else if (!(thflags & (TH_ACK|TH_FIN|TH_RST))) { 2010 goto drop; 2011 } 2012 } 2013 break; 2014 2015 /* 2016 * If the state is SYN_SENT: 2017 * if seg contains a RST with valid ACK (SEQ.ACK has already 2018 * been verified), then drop the connection. 2019 * if seg contains a RST without an ACK, drop the seg. 2020 * if seg does not contain SYN, then drop the seg. 2021 * Otherwise this is an acceptable SYN segment 2022 * initialize tp->rcv_nxt and tp->irs 2023 * if seg contains ack then advance tp->snd_una 2024 * if seg contains an ECE and ECN support is enabled, the stream 2025 * is ECN capable. 2026 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 2027 * arrange for segment to be acked (eventually) 2028 * continue processing rest of data/controls, beginning with URG 2029 */ 2030 case TCPS_SYN_SENT: 2031 if ((thflags & (TH_ACK|TH_RST)) == (TH_ACK|TH_RST)) { 2032 TCP_PROBE5(connect__refused, NULL, tp, 2033 m, tp, th); 2034 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 2035 tp = tcp_drop(tp, ECONNREFUSED); 2036 } 2037 if (thflags & TH_RST) 2038 goto drop; 2039 if (!(thflags & TH_SYN)) 2040 goto drop; 2041 2042 tp->irs = th->th_seq; 2043 tcp_rcvseqinit(tp); 2044 if (thflags & TH_ACK) { 2045 int tfo_partial_ack = 0; 2046 2047 TCPSTAT_INC(tcps_connects); 2048 soisconnected(so); 2049 #ifdef MAC 2050 mac_socketpeer_set_from_mbuf(m, so); 2051 #endif 2052 /* Do window scaling on this connection? */ 2053 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2054 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2055 tp->rcv_scale = tp->request_r_scale; 2056 } 2057 tp->rcv_adv += min(tp->rcv_wnd, 2058 TCP_MAXWIN << tp->rcv_scale); 2059 tp->snd_una++; /* SYN is acked */ 2060 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2061 tp->snd_nxt = tp->snd_una; 2062 /* 2063 * If not all the data that was sent in the TFO SYN 2064 * has been acked, resend the remainder right away. 2065 */ 2066 if (IS_FASTOPEN(tp->t_flags) && 2067 (tp->snd_una != tp->snd_max)) { 2068 tp->snd_nxt = th->th_ack; 2069 tfo_partial_ack = 1; 2070 } 2071 /* 2072 * If there's data, delay ACK; if there's also a FIN 2073 * ACKNOW will be turned on later. 2074 */ 2075 if (DELAY_ACK(tp, tlen) && tlen != 0 && !tfo_partial_ack) 2076 tcp_timer_activate(tp, TT_DELACK, 2077 tcp_delacktime); 2078 else 2079 tp->t_flags |= TF_ACKNOW; 2080 2081 tcp_ecn_input_syn_sent(tp, thflags, iptos); 2082 2083 /* 2084 * Received <SYN,ACK> in SYN_SENT[*] state. 2085 * Transitions: 2086 * SYN_SENT --> ESTABLISHED 2087 * SYN_SENT* --> FIN_WAIT_1 2088 */ 2089 tp->t_starttime = ticks; 2090 if (tp->t_flags & TF_NEEDFIN) { 2091 tp->t_acktime = ticks; 2092 tcp_state_change(tp, TCPS_FIN_WAIT_1); 2093 tp->t_flags &= ~TF_NEEDFIN; 2094 thflags &= ~TH_SYN; 2095 } else { 2096 tcp_state_change(tp, TCPS_ESTABLISHED); 2097 TCP_PROBE5(connect__established, NULL, tp, 2098 m, tp, th); 2099 cc_conn_init(tp); 2100 tcp_timer_activate(tp, TT_KEEP, 2101 TP_KEEPIDLE(tp)); 2102 } 2103 } else { 2104 /* 2105 * Received initial SYN in SYN-SENT[*] state => 2106 * simultaneous open. 2107 * If it succeeds, connection is * half-synchronized. 2108 * Otherwise, do 3-way handshake: 2109 * SYN-SENT -> SYN-RECEIVED 2110 * SYN-SENT* -> SYN-RECEIVED* 2111 */ 2112 tp->t_flags |= (TF_ACKNOW | TF_NEEDSYN | TF_SONOTCONN); 2113 tcp_timer_activate(tp, TT_REXMT, 0); 2114 tcp_state_change(tp, TCPS_SYN_RECEIVED); 2115 } 2116 2117 /* 2118 * Advance th->th_seq to correspond to first data byte. 2119 * If data, trim to stay within window, 2120 * dropping FIN if necessary. 2121 */ 2122 th->th_seq++; 2123 if (tlen > tp->rcv_wnd) { 2124 todrop = tlen - tp->rcv_wnd; 2125 m_adj(m, -todrop); 2126 tlen = tp->rcv_wnd; 2127 thflags &= ~TH_FIN; 2128 TCPSTAT_INC(tcps_rcvpackafterwin); 2129 TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); 2130 } 2131 tp->snd_wl1 = th->th_seq - 1; 2132 tp->rcv_up = th->th_seq; 2133 /* 2134 * Client side of transaction: already sent SYN and data. 2135 * If the remote host used T/TCP to validate the SYN, 2136 * our data will be ACK'd; if so, enter normal data segment 2137 * processing in the middle of step 5, ack processing. 2138 * Otherwise, goto step 6. 2139 */ 2140 if (thflags & TH_ACK) 2141 goto process_ACK; 2142 2143 goto step6; 2144 } 2145 2146 /* 2147 * States other than LISTEN or SYN_SENT. 2148 * First check the RST flag and sequence number since reset segments 2149 * are exempt from the timestamp and connection count tests. This 2150 * fixes a bug introduced by the Stevens, vol. 2, p. 960 bugfix 2151 * below which allowed reset segments in half the sequence space 2152 * to fall though and be processed (which gives forged reset 2153 * segments with a random sequence number a 50 percent chance of 2154 * killing a connection). 2155 * Then check timestamp, if present. 2156 * Then check the connection count, if present. 2157 * Then check that at least some bytes of segment are within 2158 * receive window. If segment begins before rcv_nxt, 2159 * drop leading data (and SYN); if nothing left, just ack. 2160 */ 2161 if (thflags & TH_RST) { 2162 /* 2163 * RFC5961 Section 3.2 2164 * 2165 * - RST drops connection only if SEG.SEQ == RCV.NXT. 2166 * - If RST is in window, we send challenge ACK. 2167 * 2168 * Note: to take into account delayed ACKs, we should 2169 * test against last_ack_sent instead of rcv_nxt. 2170 * Note 2: we handle special case of closed window, not 2171 * covered by the RFC. 2172 */ 2173 if ((SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 2174 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) || 2175 (tp->rcv_wnd == 0 && tp->last_ack_sent == th->th_seq)) { 2176 KASSERT(tp->t_state != TCPS_SYN_SENT, 2177 ("%s: TH_RST for TCPS_SYN_SENT th %p tp %p", 2178 __func__, th, tp)); 2179 2180 if (V_tcp_insecure_rst || 2181 tp->last_ack_sent == th->th_seq) { 2182 TCPSTAT_INC(tcps_drops); 2183 /* Drop the connection. */ 2184 switch (tp->t_state) { 2185 case TCPS_SYN_RECEIVED: 2186 so->so_error = ECONNREFUSED; 2187 goto close; 2188 case TCPS_ESTABLISHED: 2189 case TCPS_FIN_WAIT_1: 2190 case TCPS_FIN_WAIT_2: 2191 case TCPS_CLOSE_WAIT: 2192 case TCPS_CLOSING: 2193 case TCPS_LAST_ACK: 2194 so->so_error = ECONNRESET; 2195 close: 2196 /* FALLTHROUGH */ 2197 default: 2198 tcp_log_end_status(tp, TCP_EI_STATUS_CLIENT_RST); 2199 tp = tcp_close(tp); 2200 } 2201 } else { 2202 TCPSTAT_INC(tcps_badrst); 2203 /* Send challenge ACK. */ 2204 tcp_respond(tp, mtod(m, void *), th, m, 2205 tp->rcv_nxt, tp->snd_nxt, TH_ACK); 2206 tp->last_ack_sent = tp->rcv_nxt; 2207 m = NULL; 2208 } 2209 } 2210 goto drop; 2211 } 2212 2213 /* 2214 * RFC5961 Section 4.2 2215 * Send challenge ACK for any SYN in synchronized state. 2216 */ 2217 if ((thflags & TH_SYN) && tp->t_state != TCPS_SYN_SENT && 2218 tp->t_state != TCPS_SYN_RECEIVED) { 2219 TCPSTAT_INC(tcps_badsyn); 2220 if (V_tcp_insecure_syn && 2221 SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 2222 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) { 2223 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 2224 tp = tcp_drop(tp, ECONNRESET); 2225 rstreason = BANDLIM_UNLIMITED; 2226 } else { 2227 tcp_ecn_input_syn_sent(tp, thflags, iptos); 2228 /* Send challenge ACK. */ 2229 tcp_respond(tp, mtod(m, void *), th, m, tp->rcv_nxt, 2230 tp->snd_nxt, TH_ACK); 2231 tp->last_ack_sent = tp->rcv_nxt; 2232 m = NULL; 2233 } 2234 goto drop; 2235 } 2236 2237 /* 2238 * RFC 1323 PAWS: If we have a timestamp reply on this segment 2239 * and it's less than ts_recent, drop it. 2240 */ 2241 if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent && 2242 TSTMP_LT(to.to_tsval, tp->ts_recent)) { 2243 /* Check to see if ts_recent is over 24 days old. */ 2244 if (tcp_ts_getticks() - tp->ts_recent_age > TCP_PAWS_IDLE) { 2245 /* 2246 * Invalidate ts_recent. If this segment updates 2247 * ts_recent, the age will be reset later and ts_recent 2248 * will get a valid value. If it does not, setting 2249 * ts_recent to zero will at least satisfy the 2250 * requirement that zero be placed in the timestamp 2251 * echo reply when ts_recent isn't valid. The 2252 * age isn't reset until we get a valid ts_recent 2253 * because we don't want out-of-order segments to be 2254 * dropped when ts_recent is old. 2255 */ 2256 tp->ts_recent = 0; 2257 } else { 2258 TCPSTAT_INC(tcps_rcvduppack); 2259 TCPSTAT_ADD(tcps_rcvdupbyte, tlen); 2260 TCPSTAT_INC(tcps_pawsdrop); 2261 if (tlen) 2262 goto dropafterack; 2263 goto drop; 2264 } 2265 } 2266 2267 /* 2268 * In the SYN-RECEIVED state, validate that the packet belongs to 2269 * this connection before trimming the data to fit the receive 2270 * window. Check the sequence number versus IRS since we know 2271 * the sequence numbers haven't wrapped. This is a partial fix 2272 * for the "LAND" DoS attack. 2273 */ 2274 if (tp->t_state == TCPS_SYN_RECEIVED && SEQ_LT(th->th_seq, tp->irs)) { 2275 rstreason = BANDLIM_RST_OPENPORT; 2276 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 2277 goto dropwithreset; 2278 } 2279 2280 todrop = tp->rcv_nxt - th->th_seq; 2281 if (todrop > 0) { 2282 if (thflags & TH_SYN) { 2283 thflags &= ~TH_SYN; 2284 th->th_seq++; 2285 if (th->th_urp > 1) 2286 th->th_urp--; 2287 else 2288 thflags &= ~TH_URG; 2289 todrop--; 2290 } 2291 /* 2292 * Following if statement from Stevens, vol. 2, p. 960. 2293 */ 2294 if (todrop > tlen 2295 || (todrop == tlen && (thflags & TH_FIN) == 0)) { 2296 /* 2297 * Any valid FIN must be to the left of the window. 2298 * At this point the FIN must be a duplicate or out 2299 * of sequence; drop it. 2300 */ 2301 thflags &= ~TH_FIN; 2302 2303 /* 2304 * Send an ACK to resynchronize and drop any data. 2305 * But keep on processing for RST or ACK. 2306 */ 2307 tp->t_flags |= TF_ACKNOW; 2308 todrop = tlen; 2309 TCPSTAT_INC(tcps_rcvduppack); 2310 TCPSTAT_ADD(tcps_rcvdupbyte, todrop); 2311 } else { 2312 TCPSTAT_INC(tcps_rcvpartduppack); 2313 TCPSTAT_ADD(tcps_rcvpartdupbyte, todrop); 2314 } 2315 /* 2316 * DSACK - add SACK block for dropped range 2317 */ 2318 if ((todrop > 0) && (tp->t_flags & TF_SACK_PERMIT)) { 2319 tcp_update_sack_list(tp, th->th_seq, 2320 th->th_seq + todrop); 2321 /* 2322 * ACK now, as the next in-sequence segment 2323 * will clear the DSACK block again 2324 */ 2325 tp->t_flags |= TF_ACKNOW; 2326 } 2327 drop_hdrlen += todrop; /* drop from the top afterwards */ 2328 th->th_seq += todrop; 2329 tlen -= todrop; 2330 if (th->th_urp > todrop) 2331 th->th_urp -= todrop; 2332 else { 2333 thflags &= ~TH_URG; 2334 th->th_urp = 0; 2335 } 2336 } 2337 2338 /* 2339 * If new data are received on a connection after the 2340 * user processes are gone, then RST the other end. 2341 */ 2342 if ((tp->t_flags & TF_CLOSED) && tlen) { 2343 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 2344 log(LOG_DEBUG, "%s; %s: %s: Received %d bytes of data " 2345 "after socket was closed, " 2346 "sending RST and removing tcpcb\n", 2347 s, __func__, tcpstates[tp->t_state], tlen); 2348 free(s, M_TCPLOG); 2349 } 2350 tcp_log_end_status(tp, TCP_EI_STATUS_DATA_A_CLOSE); 2351 /* tcp_close will kill the inp pre-log the Reset */ 2352 tcp_log_end_status(tp, TCP_EI_STATUS_SERVER_RST); 2353 tp = tcp_close(tp); 2354 TCPSTAT_INC(tcps_rcvafterclose); 2355 rstreason = BANDLIM_UNLIMITED; 2356 goto dropwithreset; 2357 } 2358 2359 /* 2360 * If segment ends after window, drop trailing data 2361 * (and PUSH and FIN); if nothing left, just ACK. 2362 */ 2363 todrop = (th->th_seq + tlen) - (tp->rcv_nxt + tp->rcv_wnd); 2364 if (todrop > 0) { 2365 TCPSTAT_INC(tcps_rcvpackafterwin); 2366 if (todrop >= tlen) { 2367 TCPSTAT_ADD(tcps_rcvbyteafterwin, tlen); 2368 /* 2369 * If window is closed can only take segments at 2370 * window edge, and have to drop data and PUSH from 2371 * incoming segments. Continue processing, but 2372 * remember to ack. Otherwise, drop segment 2373 * and ack. 2374 */ 2375 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 2376 tp->t_flags |= TF_ACKNOW; 2377 TCPSTAT_INC(tcps_rcvwinprobe); 2378 } else 2379 goto dropafterack; 2380 } else 2381 TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); 2382 m_adj(m, -todrop); 2383 tlen -= todrop; 2384 thflags &= ~(TH_PUSH|TH_FIN); 2385 } 2386 2387 /* 2388 * If last ACK falls within this segment's sequence numbers, 2389 * record its timestamp. 2390 * NOTE: 2391 * 1) That the test incorporates suggestions from the latest 2392 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 2393 * 2) That updating only on newer timestamps interferes with 2394 * our earlier PAWS tests, so this check should be solely 2395 * predicated on the sequence space of this segment. 2396 * 3) That we modify the segment boundary check to be 2397 * Last.ACK.Sent <= SEG.SEQ + SEG.Len 2398 * instead of RFC1323's 2399 * Last.ACK.Sent < SEG.SEQ + SEG.Len, 2400 * This modified check allows us to overcome RFC1323's 2401 * limitations as described in Stevens TCP/IP Illustrated 2402 * Vol. 2 p.869. In such cases, we can still calculate the 2403 * RTT correctly when RCV.NXT == Last.ACK.Sent. 2404 */ 2405 if ((to.to_flags & TOF_TS) != 0 && 2406 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 2407 SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen + 2408 ((thflags & (TH_SYN|TH_FIN)) != 0))) { 2409 tp->ts_recent_age = tcp_ts_getticks(); 2410 tp->ts_recent = to.to_tsval; 2411 } 2412 2413 /* 2414 * If the ACK bit is off: if in SYN-RECEIVED state or SENDSYN 2415 * flag is on (half-synchronized state), then queue data for 2416 * later processing; else drop segment and return. 2417 */ 2418 if ((thflags & TH_ACK) == 0) { 2419 if (tp->t_state == TCPS_SYN_RECEIVED || 2420 (tp->t_flags & TF_NEEDSYN)) { 2421 if (tp->t_state == TCPS_SYN_RECEIVED && 2422 IS_FASTOPEN(tp->t_flags)) { 2423 tp->snd_wnd = tiwin; 2424 cc_conn_init(tp); 2425 } 2426 goto step6; 2427 } else if (tp->t_flags & TF_ACKNOW) 2428 goto dropafterack; 2429 else 2430 goto drop; 2431 } 2432 2433 /* 2434 * Ack processing. 2435 */ 2436 switch (tp->t_state) { 2437 /* 2438 * In SYN_RECEIVED state, the ack ACKs our SYN, so enter 2439 * ESTABLISHED state and continue processing. 2440 * The ACK was checked above. 2441 */ 2442 case TCPS_SYN_RECEIVED: 2443 2444 TCPSTAT_INC(tcps_connects); 2445 if (tp->t_flags & TF_SONOTCONN) { 2446 /* 2447 * Usually SYN_RECEIVED had been created from a LISTEN, 2448 * and solisten_enqueue() has already marked the socket 2449 * layer as connected. If it didn't, which can happen 2450 * only with an accept_filter(9), then the tp is marked 2451 * with TF_SONOTCONN. The other reason for this mark 2452 * to be set is a simultaneous open, a SYN_RECEIVED 2453 * that had been created from SYN_SENT. 2454 */ 2455 tp->t_flags &= ~TF_SONOTCONN; 2456 soisconnected(so); 2457 } 2458 /* Do window scaling? */ 2459 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2460 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2461 tp->rcv_scale = tp->request_r_scale; 2462 } 2463 tp->snd_wnd = tiwin; 2464 /* 2465 * Make transitions: 2466 * SYN-RECEIVED -> ESTABLISHED 2467 * SYN-RECEIVED* -> FIN-WAIT-1 2468 */ 2469 tp->t_starttime = ticks; 2470 if (IS_FASTOPEN(tp->t_flags) && tp->t_tfo_pending) { 2471 tcp_fastopen_decrement_counter(tp->t_tfo_pending); 2472 tp->t_tfo_pending = NULL; 2473 } 2474 if (tp->t_flags & TF_NEEDFIN) { 2475 tp->t_acktime = ticks; 2476 tcp_state_change(tp, TCPS_FIN_WAIT_1); 2477 tp->t_flags &= ~TF_NEEDFIN; 2478 } else { 2479 tcp_state_change(tp, TCPS_ESTABLISHED); 2480 TCP_PROBE5(accept__established, NULL, tp, 2481 m, tp, th); 2482 /* 2483 * TFO connections call cc_conn_init() during SYN 2484 * processing. Calling it again here for such 2485 * connections is not harmless as it would undo the 2486 * snd_cwnd reduction that occurs when a TFO SYN|ACK 2487 * is retransmitted. 2488 */ 2489 if (!IS_FASTOPEN(tp->t_flags)) 2490 cc_conn_init(tp); 2491 tcp_timer_activate(tp, TT_KEEP, TP_KEEPIDLE(tp)); 2492 } 2493 /* 2494 * Account for the ACK of our SYN prior to 2495 * regular ACK processing below, except for 2496 * simultaneous SYN, which is handled later. 2497 */ 2498 if (SEQ_GT(th->th_ack, tp->snd_una) && !(tp->t_flags & TF_NEEDSYN)) 2499 incforsyn = 1; 2500 /* 2501 * If segment contains data or ACK, will call tcp_reass() 2502 * later; if not, do so now to pass queued data to user. 2503 */ 2504 if (tlen == 0 && (thflags & TH_FIN) == 0) { 2505 (void) tcp_reass(tp, (struct tcphdr *)0, NULL, 0, 2506 (struct mbuf *)0); 2507 tcp_handle_wakeup(tp); 2508 } 2509 tp->snd_wl1 = th->th_seq - 1; 2510 /* FALLTHROUGH */ 2511 2512 /* 2513 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 2514 * ACKs. If the ack is in the range 2515 * tp->snd_una < th->th_ack <= tp->snd_max 2516 * then advance tp->snd_una to th->th_ack and drop 2517 * data from the retransmission queue. If this ACK reflects 2518 * more up to date window information we update our window information. 2519 */ 2520 case TCPS_ESTABLISHED: 2521 case TCPS_FIN_WAIT_1: 2522 case TCPS_FIN_WAIT_2: 2523 case TCPS_CLOSE_WAIT: 2524 case TCPS_CLOSING: 2525 case TCPS_LAST_ACK: 2526 if (SEQ_GT(th->th_ack, tp->snd_max)) { 2527 TCPSTAT_INC(tcps_rcvacktoomuch); 2528 goto dropafterack; 2529 } 2530 if (tcp_is_sack_recovery(tp, &to)) { 2531 sack_changed = tcp_sack_doack(tp, &to, th->th_ack); 2532 if ((sack_changed != SACK_NOCHANGE) && 2533 (tp->t_flags & TF_LRD)) { 2534 tcp_sack_lost_retransmission(tp, th); 2535 } 2536 } else 2537 /* 2538 * Reset the value so that previous (valid) value 2539 * from the last ack with SACK doesn't get used. 2540 */ 2541 tp->sackhint.sacked_bytes = 0; 2542 2543 #ifdef TCP_HHOOK 2544 /* Run HHOOK_TCP_ESTABLISHED_IN helper hooks. */ 2545 hhook_run_tcp_est_in(tp, th, &to); 2546 #endif 2547 2548 if (SEQ_LEQ(th->th_ack, tp->snd_una)) { 2549 maxseg = tcp_maxseg(tp); 2550 if (tlen == 0 && 2551 (tiwin == tp->snd_wnd || 2552 (tp->t_flags & TF_SACK_PERMIT))) { 2553 /* 2554 * If this is the first time we've seen a 2555 * FIN from the remote, this is not a 2556 * duplicate and it needs to be processed 2557 * normally. This happens during a 2558 * simultaneous close. 2559 */ 2560 if ((thflags & TH_FIN) && 2561 (TCPS_HAVERCVDFIN(tp->t_state) == 0)) { 2562 tp->t_dupacks = 0; 2563 break; 2564 } 2565 TCPSTAT_INC(tcps_rcvdupack); 2566 /* 2567 * If we have outstanding data (other than 2568 * a window probe), this is a completely 2569 * duplicate ack (ie, window info didn't 2570 * change and FIN isn't set), 2571 * the ack is the biggest we've 2572 * seen and we've seen exactly our rexmt 2573 * threshold of them, assume a packet 2574 * has been dropped and retransmit it. 2575 * Kludge snd_nxt & the congestion 2576 * window so we send only this one 2577 * packet. 2578 * 2579 * We know we're losing at the current 2580 * window size so do congestion avoidance 2581 * (set ssthresh to half the current window 2582 * and pull our congestion window back to 2583 * the new ssthresh). 2584 * 2585 * Dup acks mean that packets have left the 2586 * network (they're now cached at the receiver) 2587 * so bump cwnd by the amount in the receiver 2588 * to keep a constant cwnd packets in the 2589 * network. 2590 * 2591 * When using TCP ECN, notify the peer that 2592 * we reduced the cwnd. 2593 */ 2594 /* 2595 * Following 2 kinds of acks should not affect 2596 * dupack counting: 2597 * 1) Old acks 2598 * 2) Acks with SACK but without any new SACK 2599 * information in them. These could result from 2600 * any anomaly in the network like a switch 2601 * duplicating packets or a possible DoS attack. 2602 */ 2603 if (th->th_ack != tp->snd_una || 2604 (tcp_is_sack_recovery(tp, &to) && 2605 (sack_changed == SACK_NOCHANGE))) { 2606 break; 2607 } else if (!tcp_timer_active(tp, TT_REXMT)) { 2608 tp->t_dupacks = 0; 2609 } else if (++tp->t_dupacks > tcprexmtthresh || 2610 IN_FASTRECOVERY(tp->t_flags)) { 2611 cc_ack_received(tp, th, nsegs, 2612 CC_DUPACK); 2613 if (V_tcp_do_prr && 2614 IN_FASTRECOVERY(tp->t_flags) && 2615 (tp->t_flags & TF_SACK_PERMIT)) { 2616 tcp_do_prr_ack(tp, th, &to, 2617 sack_changed, &maxseg); 2618 } else if (tcp_is_sack_recovery(tp, &to) && 2619 IN_FASTRECOVERY(tp->t_flags)) { 2620 int awnd; 2621 2622 /* 2623 * Compute the amount of data in flight first. 2624 * We can inject new data into the pipe iff 2625 * we have less than 1/2 the original window's 2626 * worth of data in flight. 2627 */ 2628 if (V_tcp_do_newsack) { 2629 awnd = tcp_compute_pipe(tp); 2630 } else { 2631 awnd = (tp->snd_nxt - tp->snd_fack) + 2632 tp->sackhint.sack_bytes_rexmit; 2633 } 2634 if (awnd < tp->snd_ssthresh) { 2635 tp->snd_cwnd += maxseg; 2636 if (tp->snd_cwnd > tp->snd_ssthresh) 2637 tp->snd_cwnd = tp->snd_ssthresh; 2638 } 2639 } else { 2640 tp->snd_cwnd += maxseg; 2641 } 2642 (void) tcp_output(tp); 2643 goto drop; 2644 } else if (tp->t_dupacks == tcprexmtthresh || 2645 (tp->t_flags & TF_SACK_PERMIT && 2646 V_tcp_do_newsack && 2647 tp->sackhint.sacked_bytes > 2648 (tcprexmtthresh - 1) * maxseg)) { 2649 enter_recovery: 2650 /* 2651 * Above is the RFC6675 trigger condition of 2652 * more than (dupthresh-1)*maxseg sacked data. 2653 * If the count of holes in the 2654 * scoreboard is >= dupthresh, we could 2655 * also enter loss recovery, but don't 2656 * have that value readily available. 2657 */ 2658 tp->t_dupacks = tcprexmtthresh; 2659 tcp_seq onxt = tp->snd_nxt; 2660 2661 /* 2662 * If we're doing sack, or prr, check 2663 * to see if we're already in sack 2664 * recovery. If we're not doing sack, 2665 * check to see if we're in newreno 2666 * recovery. 2667 */ 2668 if (V_tcp_do_prr || 2669 (tp->t_flags & TF_SACK_PERMIT)) { 2670 if (IN_FASTRECOVERY(tp->t_flags)) { 2671 tp->t_dupacks = 0; 2672 break; 2673 } 2674 } else { 2675 if (SEQ_LEQ(th->th_ack, 2676 tp->snd_recover)) { 2677 tp->t_dupacks = 0; 2678 break; 2679 } 2680 } 2681 /* Congestion signal before ack. */ 2682 cc_cong_signal(tp, th, CC_NDUPACK); 2683 cc_ack_received(tp, th, nsegs, 2684 CC_DUPACK); 2685 tcp_timer_activate(tp, TT_REXMT, 0); 2686 tp->t_rtttime = 0; 2687 if (V_tcp_do_prr) { 2688 /* 2689 * snd_ssthresh is already updated by 2690 * cc_cong_signal. 2691 */ 2692 if (tcp_is_sack_recovery(tp, &to)) { 2693 /* 2694 * Exclude Limited Transmit 2695 * segments here 2696 */ 2697 tp->sackhint.prr_delivered = 2698 maxseg; 2699 } else { 2700 tp->sackhint.prr_delivered = 2701 imin(tp->snd_max - tp->snd_una, 2702 imin(INT_MAX / 65536, 2703 tp->t_dupacks) * maxseg); 2704 } 2705 tp->sackhint.recover_fs = max(1, 2706 tp->snd_nxt - tp->snd_una); 2707 } 2708 if (tcp_is_sack_recovery(tp, &to)) { 2709 TCPSTAT_INC(tcps_sack_recovery_episode); 2710 tp->snd_recover = tp->snd_nxt; 2711 tp->snd_cwnd = maxseg; 2712 (void) tcp_output(tp); 2713 if (SEQ_GT(th->th_ack, tp->snd_una)) { 2714 goto resume_partialack; 2715 } 2716 goto drop; 2717 } 2718 tp->snd_nxt = th->th_ack; 2719 tp->snd_cwnd = maxseg; 2720 (void) tcp_output(tp); 2721 KASSERT(tp->snd_limited <= 2, 2722 ("%s: tp->snd_limited too big", 2723 __func__)); 2724 tp->snd_cwnd = tp->snd_ssthresh + 2725 maxseg * 2726 (tp->t_dupacks - tp->snd_limited); 2727 if (SEQ_GT(onxt, tp->snd_nxt)) 2728 tp->snd_nxt = onxt; 2729 goto drop; 2730 } else if (V_tcp_do_rfc3042) { 2731 /* 2732 * Process first and second duplicate 2733 * ACKs. Each indicates a segment 2734 * leaving the network, creating room 2735 * for more. Make sure we can send a 2736 * packet on reception of each duplicate 2737 * ACK by increasing snd_cwnd by one 2738 * segment. Restore the original 2739 * snd_cwnd after packet transmission. 2740 */ 2741 cc_ack_received(tp, th, nsegs, CC_DUPACK); 2742 uint32_t oldcwnd = tp->snd_cwnd; 2743 tcp_seq oldsndmax = tp->snd_max; 2744 u_int sent; 2745 int avail; 2746 2747 KASSERT(tp->t_dupacks == 1 || 2748 tp->t_dupacks == 2, 2749 ("%s: dupacks not 1 or 2", 2750 __func__)); 2751 if (tp->t_dupacks == 1) 2752 tp->snd_limited = 0; 2753 tp->snd_cwnd = 2754 (tp->snd_nxt - tp->snd_una) + 2755 (tp->t_dupacks - tp->snd_limited) * 2756 maxseg; 2757 /* 2758 * Only call tcp_output when there 2759 * is new data available to be sent 2760 * or we need to send an ACK. 2761 */ 2762 SOCKBUF_LOCK(&so->so_snd); 2763 avail = sbavail(&so->so_snd); 2764 SOCKBUF_UNLOCK(&so->so_snd); 2765 if (tp->t_flags & TF_ACKNOW || 2766 (avail >= 2767 SEQ_SUB(tp->snd_nxt, tp->snd_una))) { 2768 (void) tcp_output(tp); 2769 } 2770 sent = SEQ_SUB(tp->snd_max, oldsndmax); 2771 if (sent > maxseg) { 2772 KASSERT((tp->t_dupacks == 2 && 2773 tp->snd_limited == 0) || 2774 (sent == maxseg + 1 && 2775 tp->t_flags & TF_SENTFIN), 2776 ("%s: sent too much", 2777 __func__)); 2778 tp->snd_limited = 2; 2779 } else if (sent > 0) { 2780 ++tp->snd_limited; 2781 } 2782 tp->snd_cwnd = oldcwnd; 2783 goto drop; 2784 } 2785 } 2786 break; 2787 } else { 2788 /* 2789 * This ack is advancing the left edge, reset the 2790 * counter. 2791 */ 2792 tp->t_dupacks = 0; 2793 /* 2794 * If this ack also has new SACK info, increment the 2795 * counter as per rfc6675. The variable 2796 * sack_changed tracks all changes to the SACK 2797 * scoreboard, including when partial ACKs without 2798 * SACK options are received, and clear the scoreboard 2799 * from the left side. Such partial ACKs should not be 2800 * counted as dupacks here. 2801 */ 2802 if (tcp_is_sack_recovery(tp, &to) && 2803 (sack_changed != SACK_NOCHANGE)) { 2804 tp->t_dupacks++; 2805 /* limit overhead by setting maxseg last */ 2806 if (!IN_FASTRECOVERY(tp->t_flags) && 2807 (tp->sackhint.sacked_bytes > 2808 ((tcprexmtthresh - 1) * 2809 (maxseg = tcp_maxseg(tp))))) { 2810 goto enter_recovery; 2811 } 2812 } 2813 } 2814 2815 resume_partialack: 2816 KASSERT(SEQ_GT(th->th_ack, tp->snd_una), 2817 ("%s: th_ack <= snd_una", __func__)); 2818 2819 /* 2820 * If the congestion window was inflated to account 2821 * for the other side's cached packets, retract it. 2822 */ 2823 if (SEQ_LT(th->th_ack, tp->snd_recover)) { 2824 if (IN_FASTRECOVERY(tp->t_flags)) { 2825 if (tp->t_flags & TF_SACK_PERMIT) { 2826 if (V_tcp_do_prr && 2827 (to.to_flags & TOF_SACK)) { 2828 tcp_timer_activate(tp, 2829 TT_REXMT, 0); 2830 tp->t_rtttime = 0; 2831 tcp_do_prr_ack(tp, th, &to, 2832 sack_changed, &maxseg); 2833 tp->t_flags |= TF_ACKNOW; 2834 (void) tcp_output(tp); 2835 } else { 2836 tcp_sack_partialack(tp, th, 2837 &maxseg); 2838 } 2839 } else { 2840 tcp_newreno_partial_ack(tp, th); 2841 } 2842 } else if (IN_CONGRECOVERY(tp->t_flags) && 2843 (V_tcp_do_prr)) { 2844 tp->sackhint.delivered_data = 2845 BYTES_THIS_ACK(tp, th); 2846 tp->snd_fack = th->th_ack; 2847 /* 2848 * During ECN cwnd reduction 2849 * always use PRR-SSRB 2850 */ 2851 tcp_do_prr_ack(tp, th, &to, SACK_CHANGE, 2852 &maxseg); 2853 (void) tcp_output(tp); 2854 } 2855 } 2856 /* 2857 * If we reach this point, ACK is not a duplicate, 2858 * i.e., it ACKs something we sent. 2859 */ 2860 if (tp->t_flags & TF_NEEDSYN) { 2861 /* 2862 * T/TCP: Connection was half-synchronized, and our 2863 * SYN has been ACK'd (so connection is now fully 2864 * synchronized). Go to non-starred state, 2865 * increment snd_una for ACK of SYN, and check if 2866 * we can do window scaling. 2867 */ 2868 tp->t_flags &= ~TF_NEEDSYN; 2869 tp->snd_una++; 2870 /* Do window scaling? */ 2871 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2872 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2873 tp->rcv_scale = tp->request_r_scale; 2874 /* Send window already scaled. */ 2875 } 2876 } 2877 2878 process_ACK: 2879 INP_WLOCK_ASSERT(inp); 2880 2881 /* 2882 * Adjust for the SYN bit in sequence space, 2883 * but don't account for it in cwnd calculations. 2884 * This is for the SYN_RECEIVED, non-simultaneous 2885 * SYN case. SYN_SENT and simultaneous SYN are 2886 * treated elsewhere. 2887 */ 2888 if (incforsyn) 2889 tp->snd_una++; 2890 acked = BYTES_THIS_ACK(tp, th); 2891 KASSERT(acked >= 0, ("%s: acked unexepectedly negative " 2892 "(tp->snd_una=%u, th->th_ack=%u, tp=%p, m=%p)", __func__, 2893 tp->snd_una, th->th_ack, tp, m)); 2894 TCPSTAT_ADD(tcps_rcvackpack, nsegs); 2895 TCPSTAT_ADD(tcps_rcvackbyte, acked); 2896 2897 /* 2898 * If we just performed our first retransmit, and the ACK 2899 * arrives within our recovery window, then it was a mistake 2900 * to do the retransmit in the first place. Recover our 2901 * original cwnd and ssthresh, and proceed to transmit where 2902 * we left off. 2903 */ 2904 if (tp->t_rxtshift == 1 && 2905 tp->t_flags & TF_PREVVALID && 2906 tp->t_badrxtwin != 0 && 2907 to.to_flags & TOF_TS && 2908 to.to_tsecr != 0 && 2909 TSTMP_LT(to.to_tsecr, tp->t_badrxtwin)) 2910 cc_cong_signal(tp, th, CC_RTO_ERR); 2911 2912 /* 2913 * If we have a timestamp reply, update smoothed 2914 * round trip time. If no timestamp is present but 2915 * transmit timer is running and timed sequence 2916 * number was acked, update smoothed round trip time. 2917 * Since we now have an rtt measurement, cancel the 2918 * timer backoff (cf., Phil Karn's retransmit alg.). 2919 * Recompute the initial retransmit timer. 2920 * 2921 * Some boxes send broken timestamp replies 2922 * during the SYN+ACK phase, ignore 2923 * timestamps of 0 or we could calculate a 2924 * huge RTT and blow up the retransmit timer. 2925 */ 2926 if ((to.to_flags & TOF_TS) != 0 && to.to_tsecr) { 2927 uint32_t t; 2928 2929 t = tcp_ts_getticks() - to.to_tsecr; 2930 if (!tp->t_rttlow || tp->t_rttlow > t) 2931 tp->t_rttlow = t; 2932 tcp_xmit_timer(tp, TCP_TS_TO_TICKS(t) + 1); 2933 } else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) { 2934 if (!tp->t_rttlow || tp->t_rttlow > ticks - tp->t_rtttime) 2935 tp->t_rttlow = ticks - tp->t_rtttime; 2936 tcp_xmit_timer(tp, ticks - tp->t_rtttime); 2937 } 2938 2939 SOCKBUF_LOCK(&so->so_snd); 2940 /* 2941 * Clear t_acktime if remote side has ACKd all data in the 2942 * socket buffer and FIN (if applicable). 2943 * Otherwise, update t_acktime if we received a sufficiently 2944 * large ACK. 2945 */ 2946 if ((tp->t_state <= TCPS_CLOSE_WAIT && 2947 acked == sbavail(&so->so_snd)) || 2948 acked > sbavail(&so->so_snd)) 2949 tp->t_acktime = 0; 2950 else if (acked > 1) 2951 tp->t_acktime = ticks; 2952 2953 /* 2954 * If all outstanding data is acked, stop retransmit 2955 * timer and remember to restart (more output or persist). 2956 * If there is more data to be acked, restart retransmit 2957 * timer, using current (possibly backed-off) value. 2958 */ 2959 if (th->th_ack == tp->snd_max) { 2960 tcp_timer_activate(tp, TT_REXMT, 0); 2961 needoutput = 1; 2962 } else if (!tcp_timer_active(tp, TT_PERSIST)) 2963 tcp_timer_activate(tp, TT_REXMT, TP_RXTCUR(tp)); 2964 2965 /* 2966 * If no data (only SYN) was ACK'd, 2967 * skip rest of ACK processing. 2968 */ 2969 if (acked == 0) { 2970 SOCKBUF_UNLOCK(&so->so_snd); 2971 goto step6; 2972 } 2973 2974 /* 2975 * Let the congestion control algorithm update congestion 2976 * control related information. This typically means increasing 2977 * the congestion window. 2978 */ 2979 cc_ack_received(tp, th, nsegs, CC_ACK); 2980 2981 if (acked > sbavail(&so->so_snd)) { 2982 if (tp->snd_wnd >= sbavail(&so->so_snd)) 2983 tp->snd_wnd -= sbavail(&so->so_snd); 2984 else 2985 tp->snd_wnd = 0; 2986 mfree = sbcut_locked(&so->so_snd, 2987 (int)sbavail(&so->so_snd)); 2988 ourfinisacked = 1; 2989 } else { 2990 mfree = sbcut_locked(&so->so_snd, acked); 2991 if (tp->snd_wnd >= (uint32_t) acked) 2992 tp->snd_wnd -= acked; 2993 else 2994 tp->snd_wnd = 0; 2995 ourfinisacked = 0; 2996 } 2997 /* NB: sowwakeup_locked() does an implicit unlock. */ 2998 sowwakeup_locked(so); 2999 m_freem(mfree); 3000 /* Detect una wraparound. */ 3001 if (!IN_RECOVERY(tp->t_flags) && 3002 SEQ_GT(tp->snd_una, tp->snd_recover) && 3003 SEQ_LEQ(th->th_ack, tp->snd_recover)) 3004 tp->snd_recover = th->th_ack - 1; 3005 tp->snd_una = th->th_ack; 3006 if (IN_RECOVERY(tp->t_flags) && 3007 SEQ_GEQ(th->th_ack, tp->snd_recover)) { 3008 cc_post_recovery(tp, th); 3009 } 3010 if (tp->t_flags & TF_SACK_PERMIT) { 3011 if (SEQ_GT(tp->snd_una, tp->snd_recover)) 3012 tp->snd_recover = tp->snd_una; 3013 } 3014 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 3015 tp->snd_nxt = tp->snd_una; 3016 3017 switch (tp->t_state) { 3018 /* 3019 * In FIN_WAIT_1 STATE in addition to the processing 3020 * for the ESTABLISHED state if our FIN is now acknowledged 3021 * then enter FIN_WAIT_2. 3022 */ 3023 case TCPS_FIN_WAIT_1: 3024 if (ourfinisacked) { 3025 /* 3026 * If we can't receive any more 3027 * data, then closing user can proceed. 3028 * Starting the timer is contrary to the 3029 * specification, but if we don't get a FIN 3030 * we'll hang forever. 3031 */ 3032 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 3033 tcp_free_sackholes(tp); 3034 soisdisconnected(so); 3035 tcp_timer_activate(tp, TT_2MSL, 3036 (tcp_fast_finwait2_recycle ? 3037 tcp_finwait2_timeout : 3038 TP_MAXIDLE(tp))); 3039 } 3040 tcp_state_change(tp, TCPS_FIN_WAIT_2); 3041 } 3042 break; 3043 3044 /* 3045 * In CLOSING STATE in addition to the processing for 3046 * the ESTABLISHED state if the ACK acknowledges our FIN 3047 * then enter the TIME-WAIT state, otherwise ignore 3048 * the segment. 3049 */ 3050 case TCPS_CLOSING: 3051 if (ourfinisacked) { 3052 tcp_twstart(tp); 3053 m_freem(m); 3054 return; 3055 } 3056 break; 3057 3058 /* 3059 * In LAST_ACK, we may still be waiting for data to drain 3060 * and/or to be acked, as well as for the ack of our FIN. 3061 * If our FIN is now acknowledged, delete the TCB, 3062 * enter the closed state and return. 3063 */ 3064 case TCPS_LAST_ACK: 3065 if (ourfinisacked) { 3066 tp = tcp_close(tp); 3067 goto drop; 3068 } 3069 break; 3070 } 3071 } 3072 3073 step6: 3074 INP_WLOCK_ASSERT(inp); 3075 3076 /* 3077 * Update window information. 3078 * Don't look at window if no ACK: TAC's send garbage on first SYN. 3079 */ 3080 if ((thflags & TH_ACK) && 3081 (SEQ_LT(tp->snd_wl1, th->th_seq) || 3082 (tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) || 3083 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) { 3084 /* keep track of pure window updates */ 3085 if (tlen == 0 && 3086 tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) 3087 TCPSTAT_INC(tcps_rcvwinupd); 3088 tp->snd_wnd = tiwin; 3089 tp->snd_wl1 = th->th_seq; 3090 tp->snd_wl2 = th->th_ack; 3091 if (tp->snd_wnd > tp->max_sndwnd) 3092 tp->max_sndwnd = tp->snd_wnd; 3093 needoutput = 1; 3094 } 3095 3096 /* 3097 * Process segments with URG. 3098 */ 3099 if ((thflags & TH_URG) && th->th_urp && 3100 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3101 /* 3102 * This is a kludge, but if we receive and accept 3103 * random urgent pointers, we'll crash in 3104 * soreceive. It's hard to imagine someone 3105 * actually wanting to send this much urgent data. 3106 */ 3107 SOCKBUF_LOCK(&so->so_rcv); 3108 if (th->th_urp + sbavail(&so->so_rcv) > sb_max) { 3109 th->th_urp = 0; /* XXX */ 3110 thflags &= ~TH_URG; /* XXX */ 3111 SOCKBUF_UNLOCK(&so->so_rcv); /* XXX */ 3112 goto dodata; /* XXX */ 3113 } 3114 /* 3115 * If this segment advances the known urgent pointer, 3116 * then mark the data stream. This should not happen 3117 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 3118 * a FIN has been received from the remote side. 3119 * In these states we ignore the URG. 3120 * 3121 * According to RFC961 (Assigned Protocols), 3122 * the urgent pointer points to the last octet 3123 * of urgent data. We continue, however, 3124 * to consider it to indicate the first octet 3125 * of data past the urgent section as the original 3126 * spec states (in one of two places). 3127 */ 3128 if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) { 3129 tp->rcv_up = th->th_seq + th->th_urp; 3130 so->so_oobmark = sbavail(&so->so_rcv) + 3131 (tp->rcv_up - tp->rcv_nxt) - 1; 3132 if (so->so_oobmark == 0) 3133 so->so_rcv.sb_state |= SBS_RCVATMARK; 3134 sohasoutofband(so); 3135 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); 3136 } 3137 SOCKBUF_UNLOCK(&so->so_rcv); 3138 /* 3139 * Remove out of band data so doesn't get presented to user. 3140 * This can happen independent of advancing the URG pointer, 3141 * but if two URG's are pending at once, some out-of-band 3142 * data may creep in... ick. 3143 */ 3144 if (th->th_urp <= (uint32_t)tlen && 3145 !(so->so_options & SO_OOBINLINE)) { 3146 /* hdr drop is delayed */ 3147 tcp_pulloutofband(so, th, m, drop_hdrlen); 3148 } 3149 } else { 3150 /* 3151 * If no out of band data is expected, 3152 * pull receive urgent pointer along 3153 * with the receive window. 3154 */ 3155 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) 3156 tp->rcv_up = tp->rcv_nxt; 3157 } 3158 dodata: /* XXX */ 3159 INP_WLOCK_ASSERT(inp); 3160 3161 /* 3162 * Process the segment text, merging it into the TCP sequencing queue, 3163 * and arranging for acknowledgment of receipt if necessary. 3164 * This process logically involves adjusting tp->rcv_wnd as data 3165 * is presented to the user (this happens in tcp_usrreq.c, 3166 * case PRU_RCVD). If a FIN has already been received on this 3167 * connection then we just ignore the text. 3168 */ 3169 tfo_syn = ((tp->t_state == TCPS_SYN_RECEIVED) && 3170 IS_FASTOPEN(tp->t_flags)); 3171 if ((tlen || (thflags & TH_FIN) || (tfo_syn && tlen > 0)) && 3172 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3173 tcp_seq save_start = th->th_seq; 3174 tcp_seq save_rnxt = tp->rcv_nxt; 3175 int save_tlen = tlen; 3176 m_adj(m, drop_hdrlen); /* delayed header drop */ 3177 /* 3178 * Insert segment which includes th into TCP reassembly queue 3179 * with control block tp. Set thflags to whether reassembly now 3180 * includes a segment with FIN. This handles the common case 3181 * inline (segment is the next to be received on an established 3182 * connection, and the queue is empty), avoiding linkage into 3183 * and removal from the queue and repetition of various 3184 * conversions. 3185 * Set DELACK for segments received in order, but ack 3186 * immediately when segments are out of order (so 3187 * fast retransmit can work). 3188 */ 3189 if (th->th_seq == tp->rcv_nxt && 3190 SEGQ_EMPTY(tp) && 3191 (TCPS_HAVEESTABLISHED(tp->t_state) || 3192 tfo_syn)) { 3193 if (DELAY_ACK(tp, tlen) || tfo_syn) 3194 tp->t_flags |= TF_DELACK; 3195 else 3196 tp->t_flags |= TF_ACKNOW; 3197 tp->rcv_nxt += tlen; 3198 if (tlen && 3199 ((tp->t_flags2 & TF2_FBYTES_COMPLETE) == 0) && 3200 (tp->t_fbyte_in == 0)) { 3201 tp->t_fbyte_in = ticks; 3202 if (tp->t_fbyte_in == 0) 3203 tp->t_fbyte_in = 1; 3204 if (tp->t_fbyte_out && tp->t_fbyte_in) 3205 tp->t_flags2 |= TF2_FBYTES_COMPLETE; 3206 } 3207 thflags = tcp_get_flags(th) & TH_FIN; 3208 TCPSTAT_INC(tcps_rcvpack); 3209 TCPSTAT_ADD(tcps_rcvbyte, tlen); 3210 SOCKBUF_LOCK(&so->so_rcv); 3211 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) 3212 m_freem(m); 3213 else 3214 sbappendstream_locked(&so->so_rcv, m, 0); 3215 tp->t_flags |= TF_WAKESOR; 3216 } else { 3217 /* 3218 * XXX: Due to the header drop above "th" is 3219 * theoretically invalid by now. Fortunately 3220 * m_adj() doesn't actually frees any mbufs 3221 * when trimming from the head. 3222 */ 3223 tcp_seq temp = save_start; 3224 3225 thflags = tcp_reass(tp, th, &temp, &tlen, m); 3226 tp->t_flags |= TF_ACKNOW; 3227 } 3228 if ((tp->t_flags & TF_SACK_PERMIT) && 3229 (save_tlen > 0) && 3230 TCPS_HAVEESTABLISHED(tp->t_state)) { 3231 if ((tlen == 0) && (SEQ_LT(save_start, save_rnxt))) { 3232 /* 3233 * DSACK actually handled in the fastpath 3234 * above. 3235 */ 3236 tcp_update_sack_list(tp, save_start, 3237 save_start + save_tlen); 3238 } else if ((tlen > 0) && SEQ_GT(tp->rcv_nxt, save_rnxt)) { 3239 if ((tp->rcv_numsacks >= 1) && 3240 (tp->sackblks[0].end == save_start)) { 3241 /* 3242 * Partial overlap, recorded at todrop 3243 * above. 3244 */ 3245 tcp_update_sack_list(tp, 3246 tp->sackblks[0].start, 3247 tp->sackblks[0].end); 3248 } else { 3249 tcp_update_dsack_list(tp, save_start, 3250 save_start + save_tlen); 3251 } 3252 } else if (tlen >= save_tlen) { 3253 /* Update of sackblks. */ 3254 tcp_update_dsack_list(tp, save_start, 3255 save_start + save_tlen); 3256 } else if (tlen > 0) { 3257 tcp_update_dsack_list(tp, save_start, 3258 save_start + tlen); 3259 } 3260 } 3261 tcp_handle_wakeup(tp); 3262 #if 0 3263 /* 3264 * Note the amount of data that peer has sent into 3265 * our window, in order to estimate the sender's 3266 * buffer size. 3267 * XXX: Unused. 3268 */ 3269 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt)) 3270 len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); 3271 else 3272 len = so->so_rcv.sb_hiwat; 3273 #endif 3274 } else { 3275 m_freem(m); 3276 thflags &= ~TH_FIN; 3277 } 3278 3279 /* 3280 * If FIN is received ACK the FIN and let the user know 3281 * that the connection is closing. 3282 */ 3283 if (thflags & TH_FIN) { 3284 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3285 /* The socket upcall is handled by socantrcvmore. */ 3286 socantrcvmore(so); 3287 /* 3288 * If connection is half-synchronized 3289 * (ie NEEDSYN flag on) then delay ACK, 3290 * so it may be piggybacked when SYN is sent. 3291 * Otherwise, since we received a FIN then no 3292 * more input can be expected, send ACK now. 3293 */ 3294 if (tp->t_flags & TF_NEEDSYN) 3295 tp->t_flags |= TF_DELACK; 3296 else 3297 tp->t_flags |= TF_ACKNOW; 3298 tp->rcv_nxt++; 3299 } 3300 switch (tp->t_state) { 3301 /* 3302 * In SYN_RECEIVED and ESTABLISHED STATES 3303 * enter the CLOSE_WAIT state. 3304 */ 3305 case TCPS_SYN_RECEIVED: 3306 tp->t_starttime = ticks; 3307 /* FALLTHROUGH */ 3308 case TCPS_ESTABLISHED: 3309 tcp_state_change(tp, TCPS_CLOSE_WAIT); 3310 break; 3311 3312 /* 3313 * If still in FIN_WAIT_1 STATE FIN has not been acked so 3314 * enter the CLOSING state. 3315 */ 3316 case TCPS_FIN_WAIT_1: 3317 tcp_state_change(tp, TCPS_CLOSING); 3318 break; 3319 3320 /* 3321 * In FIN_WAIT_2 state enter the TIME_WAIT state, 3322 * starting the time-wait timer, turning off the other 3323 * standard timers. 3324 */ 3325 case TCPS_FIN_WAIT_2: 3326 tcp_twstart(tp); 3327 return; 3328 } 3329 } 3330 TCP_PROBE3(debug__input, tp, th, m); 3331 3332 /* 3333 * Return any desired output. 3334 */ 3335 if (needoutput || (tp->t_flags & TF_ACKNOW)) { 3336 (void) tcp_output(tp); 3337 } 3338 check_delack: 3339 INP_WLOCK_ASSERT(inp); 3340 3341 if (tp->t_flags & TF_DELACK) { 3342 tp->t_flags &= ~TF_DELACK; 3343 tcp_timer_activate(tp, TT_DELACK, tcp_delacktime); 3344 } 3345 INP_WUNLOCK(inp); 3346 return; 3347 3348 dropafterack: 3349 /* 3350 * Generate an ACK dropping incoming segment if it occupies 3351 * sequence space, where the ACK reflects our state. 3352 * 3353 * We can now skip the test for the RST flag since all 3354 * paths to this code happen after packets containing 3355 * RST have been dropped. 3356 * 3357 * In the SYN-RECEIVED state, don't send an ACK unless the 3358 * segment we received passes the SYN-RECEIVED ACK test. 3359 * If it fails send a RST. This breaks the loop in the 3360 * "LAND" DoS attack, and also prevents an ACK storm 3361 * between two listening ports that have been sent forged 3362 * SYN segments, each with the source address of the other. 3363 */ 3364 if (tp->t_state == TCPS_SYN_RECEIVED && (thflags & TH_ACK) && 3365 (SEQ_GT(tp->snd_una, th->th_ack) || 3366 SEQ_GT(th->th_ack, tp->snd_max)) ) { 3367 rstreason = BANDLIM_RST_OPENPORT; 3368 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 3369 goto dropwithreset; 3370 } 3371 TCP_PROBE3(debug__input, tp, th, m); 3372 tp->t_flags |= TF_ACKNOW; 3373 (void) tcp_output(tp); 3374 INP_WUNLOCK(inp); 3375 m_freem(m); 3376 return; 3377 3378 dropwithreset: 3379 if (tp != NULL) { 3380 tcp_dropwithreset(m, th, tp, tlen, rstreason); 3381 INP_WUNLOCK(inp); 3382 } else 3383 tcp_dropwithreset(m, th, NULL, tlen, rstreason); 3384 return; 3385 3386 drop: 3387 /* 3388 * Drop space held by incoming segment and return. 3389 */ 3390 TCP_PROBE3(debug__input, tp, th, m); 3391 if (tp != NULL) { 3392 INP_WUNLOCK(inp); 3393 } 3394 m_freem(m); 3395 } 3396 3397 /* 3398 * Issue RST and make ACK acceptable to originator of segment. 3399 * The mbuf must still include the original packet header. 3400 * tp may be NULL. 3401 */ 3402 void 3403 tcp_dropwithreset(struct mbuf *m, struct tcphdr *th, struct tcpcb *tp, 3404 int tlen, int rstreason) 3405 { 3406 #ifdef INET 3407 struct ip *ip; 3408 #endif 3409 #ifdef INET6 3410 struct ip6_hdr *ip6; 3411 #endif 3412 3413 if (tp != NULL) { 3414 INP_LOCK_ASSERT(tptoinpcb(tp)); 3415 } 3416 3417 /* Don't bother if destination was broadcast/multicast. */ 3418 if ((tcp_get_flags(th) & TH_RST) || m->m_flags & (M_BCAST|M_MCAST)) 3419 goto drop; 3420 #ifdef INET6 3421 if (mtod(m, struct ip *)->ip_v == 6) { 3422 ip6 = mtod(m, struct ip6_hdr *); 3423 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 3424 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) 3425 goto drop; 3426 /* IPv6 anycast check is done at tcp6_input() */ 3427 } 3428 #endif 3429 #if defined(INET) && defined(INET6) 3430 else 3431 #endif 3432 #ifdef INET 3433 { 3434 ip = mtod(m, struct ip *); 3435 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 3436 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 3437 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || 3438 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 3439 goto drop; 3440 } 3441 #endif 3442 3443 /* Perform bandwidth limiting. */ 3444 if (badport_bandlim(rstreason) < 0) 3445 goto drop; 3446 3447 /* tcp_respond consumes the mbuf chain. */ 3448 if (tcp_get_flags(th) & TH_ACK) { 3449 tcp_respond(tp, mtod(m, void *), th, m, (tcp_seq)0, 3450 th->th_ack, TH_RST); 3451 } else { 3452 if (tcp_get_flags(th) & TH_SYN) 3453 tlen++; 3454 if (tcp_get_flags(th) & TH_FIN) 3455 tlen++; 3456 tcp_respond(tp, mtod(m, void *), th, m, th->th_seq+tlen, 3457 (tcp_seq)0, TH_RST|TH_ACK); 3458 } 3459 return; 3460 drop: 3461 m_freem(m); 3462 } 3463 3464 /* 3465 * Parse TCP options and place in tcpopt. 3466 */ 3467 void 3468 tcp_dooptions(struct tcpopt *to, u_char *cp, int cnt, int flags) 3469 { 3470 int opt, optlen; 3471 3472 to->to_flags = 0; 3473 for (; cnt > 0; cnt -= optlen, cp += optlen) { 3474 opt = cp[0]; 3475 if (opt == TCPOPT_EOL) 3476 break; 3477 if (opt == TCPOPT_NOP) 3478 optlen = 1; 3479 else { 3480 if (cnt < 2) 3481 break; 3482 optlen = cp[1]; 3483 if (optlen < 2 || optlen > cnt) 3484 break; 3485 } 3486 switch (opt) { 3487 case TCPOPT_MAXSEG: 3488 if (optlen != TCPOLEN_MAXSEG) 3489 continue; 3490 if (!(flags & TO_SYN)) 3491 continue; 3492 to->to_flags |= TOF_MSS; 3493 bcopy((char *)cp + 2, 3494 (char *)&to->to_mss, sizeof(to->to_mss)); 3495 to->to_mss = ntohs(to->to_mss); 3496 break; 3497 case TCPOPT_WINDOW: 3498 if (optlen != TCPOLEN_WINDOW) 3499 continue; 3500 if (!(flags & TO_SYN)) 3501 continue; 3502 to->to_flags |= TOF_SCALE; 3503 to->to_wscale = min(cp[2], TCP_MAX_WINSHIFT); 3504 break; 3505 case TCPOPT_TIMESTAMP: 3506 if (optlen != TCPOLEN_TIMESTAMP) 3507 continue; 3508 to->to_flags |= TOF_TS; 3509 bcopy((char *)cp + 2, 3510 (char *)&to->to_tsval, sizeof(to->to_tsval)); 3511 to->to_tsval = ntohl(to->to_tsval); 3512 bcopy((char *)cp + 6, 3513 (char *)&to->to_tsecr, sizeof(to->to_tsecr)); 3514 to->to_tsecr = ntohl(to->to_tsecr); 3515 break; 3516 case TCPOPT_SIGNATURE: 3517 /* 3518 * In order to reply to a host which has set the 3519 * TCP_SIGNATURE option in its initial SYN, we have 3520 * to record the fact that the option was observed 3521 * here for the syncache code to perform the correct 3522 * response. 3523 */ 3524 if (optlen != TCPOLEN_SIGNATURE) 3525 continue; 3526 to->to_flags |= TOF_SIGNATURE; 3527 to->to_signature = cp + 2; 3528 break; 3529 case TCPOPT_SACK_PERMITTED: 3530 if (optlen != TCPOLEN_SACK_PERMITTED) 3531 continue; 3532 if (!(flags & TO_SYN)) 3533 continue; 3534 if (!V_tcp_do_sack) 3535 continue; 3536 to->to_flags |= TOF_SACKPERM; 3537 break; 3538 case TCPOPT_SACK: 3539 if (optlen <= 2 || (optlen - 2) % TCPOLEN_SACK != 0) 3540 continue; 3541 if (flags & TO_SYN) 3542 continue; 3543 to->to_flags |= TOF_SACK; 3544 to->to_nsacks = (optlen - 2) / TCPOLEN_SACK; 3545 to->to_sacks = cp + 2; 3546 TCPSTAT_INC(tcps_sack_rcv_blocks); 3547 break; 3548 case TCPOPT_FAST_OPEN: 3549 /* 3550 * Cookie length validation is performed by the 3551 * server side cookie checking code or the client 3552 * side cookie cache update code. 3553 */ 3554 if (!(flags & TO_SYN)) 3555 continue; 3556 if (!V_tcp_fastopen_client_enable && 3557 !V_tcp_fastopen_server_enable) 3558 continue; 3559 to->to_flags |= TOF_FASTOPEN; 3560 to->to_tfo_len = optlen - 2; 3561 to->to_tfo_cookie = to->to_tfo_len ? cp + 2 : NULL; 3562 break; 3563 default: 3564 continue; 3565 } 3566 } 3567 } 3568 3569 /* 3570 * Pull out of band byte out of a segment so 3571 * it doesn't appear in the user's data queue. 3572 * It is still reflected in the segment length for 3573 * sequencing purposes. 3574 */ 3575 void 3576 tcp_pulloutofband(struct socket *so, struct tcphdr *th, struct mbuf *m, 3577 int off) 3578 { 3579 int cnt = off + th->th_urp - 1; 3580 3581 while (cnt >= 0) { 3582 if (m->m_len > cnt) { 3583 char *cp = mtod(m, caddr_t) + cnt; 3584 struct tcpcb *tp = sototcpcb(so); 3585 3586 INP_WLOCK_ASSERT(tptoinpcb(tp)); 3587 3588 tp->t_iobc = *cp; 3589 tp->t_oobflags |= TCPOOB_HAVEDATA; 3590 bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); 3591 m->m_len--; 3592 if (m->m_flags & M_PKTHDR) 3593 m->m_pkthdr.len--; 3594 return; 3595 } 3596 cnt -= m->m_len; 3597 m = m->m_next; 3598 if (m == NULL) 3599 break; 3600 } 3601 panic("tcp_pulloutofband"); 3602 } 3603 3604 /* 3605 * Collect new round-trip time estimate 3606 * and update averages and current timeout. 3607 */ 3608 void 3609 tcp_xmit_timer(struct tcpcb *tp, int rtt) 3610 { 3611 int delta; 3612 3613 INP_WLOCK_ASSERT(tptoinpcb(tp)); 3614 3615 TCPSTAT_INC(tcps_rttupdated); 3616 if (tp->t_rttupdated < UCHAR_MAX) 3617 tp->t_rttupdated++; 3618 #ifdef STATS 3619 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_RTT, 3620 imax(0, rtt * 1000 / hz)); 3621 #endif 3622 if ((tp->t_srtt != 0) && (tp->t_rxtshift <= TCP_RTT_INVALIDATE)) { 3623 /* 3624 * srtt is stored as fixed point with 5 bits after the 3625 * binary point (i.e., scaled by 8). The following magic 3626 * is equivalent to the smoothing algorithm in rfc793 with 3627 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed 3628 * point). Adjust rtt to origin 0. 3629 */ 3630 delta = ((rtt - 1) << TCP_DELTA_SHIFT) 3631 - (tp->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT)); 3632 3633 if ((tp->t_srtt += delta) <= 0) 3634 tp->t_srtt = 1; 3635 3636 /* 3637 * We accumulate a smoothed rtt variance (actually, a 3638 * smoothed mean difference), then set the retransmit 3639 * timer to smoothed rtt + 4 times the smoothed variance. 3640 * rttvar is stored as fixed point with 4 bits after the 3641 * binary point (scaled by 16). The following is 3642 * equivalent to rfc793 smoothing with an alpha of .75 3643 * (rttvar = rttvar*3/4 + |delta| / 4). This replaces 3644 * rfc793's wired-in beta. 3645 */ 3646 if (delta < 0) 3647 delta = -delta; 3648 delta -= tp->t_rttvar >> (TCP_RTTVAR_SHIFT - TCP_DELTA_SHIFT); 3649 if ((tp->t_rttvar += delta) <= 0) 3650 tp->t_rttvar = 1; 3651 } else { 3652 /* 3653 * No rtt measurement yet - use the unsmoothed rtt. 3654 * Set the variance to half the rtt (so our first 3655 * retransmit happens at 3*rtt). 3656 */ 3657 tp->t_srtt = rtt << TCP_RTT_SHIFT; 3658 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1); 3659 } 3660 tp->t_rtttime = 0; 3661 tp->t_rxtshift = 0; 3662 3663 /* 3664 * the retransmit should happen at rtt + 4 * rttvar. 3665 * Because of the way we do the smoothing, srtt and rttvar 3666 * will each average +1/2 tick of bias. When we compute 3667 * the retransmit timer, we want 1/2 tick of rounding and 3668 * 1 extra tick because of +-1/2 tick uncertainty in the 3669 * firing of the timer. The bias will give us exactly the 3670 * 1.5 tick we need. But, because the bias is 3671 * statistical, we have to test that we don't drop below 3672 * the minimum feasible timer (which is 2 ticks). 3673 */ 3674 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), 3675 max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX); 3676 3677 /* 3678 * We received an ack for a packet that wasn't retransmitted; 3679 * it is probably safe to discard any error indications we've 3680 * received recently. This isn't quite right, but close enough 3681 * for now (a route might have failed after we sent a segment, 3682 * and the return path might not be symmetrical). 3683 */ 3684 tp->t_softerror = 0; 3685 } 3686 3687 /* 3688 * Determine a reasonable value for maxseg size. 3689 * If the route is known, check route for mtu. 3690 * If none, use an mss that can be handled on the outgoing interface 3691 * without forcing IP to fragment. If no route is found, route has no mtu, 3692 * or the destination isn't local, use a default, hopefully conservative 3693 * size (usually 512 or the default IP max size, but no more than the mtu 3694 * of the interface), as we can't discover anything about intervening 3695 * gateways or networks. We also initialize the congestion/slow start 3696 * window to be a single segment if the destination isn't local. 3697 * While looking at the routing entry, we also initialize other path-dependent 3698 * parameters from pre-set or cached values in the routing entry. 3699 * 3700 * NOTE that resulting t_maxseg doesn't include space for TCP options or 3701 * IP options, e.g. IPSEC data, since length of this data may vary, and 3702 * thus it is calculated for every segment separately in tcp_output(). 3703 * 3704 * NOTE that this routine is only called when we process an incoming 3705 * segment, or an ICMP need fragmentation datagram. Outgoing SYN/ACK MSS 3706 * settings are handled in tcp_mssopt(). 3707 */ 3708 void 3709 tcp_mss_update(struct tcpcb *tp, int offer, int mtuoffer, 3710 struct hc_metrics_lite *metricptr, struct tcp_ifcap *cap) 3711 { 3712 int mss = 0; 3713 uint32_t maxmtu = 0; 3714 struct inpcb *inp = tptoinpcb(tp); 3715 struct hc_metrics_lite metrics; 3716 #ifdef INET6 3717 int isipv6 = ((inp->inp_vflag & INP_IPV6) != 0) ? 1 : 0; 3718 size_t min_protoh = isipv6 ? 3719 sizeof (struct ip6_hdr) + sizeof (struct tcphdr) : 3720 sizeof (struct tcpiphdr); 3721 #else 3722 size_t min_protoh = sizeof(struct tcpiphdr); 3723 #endif 3724 3725 INP_WLOCK_ASSERT(inp); 3726 3727 if (tp->t_port) 3728 min_protoh += V_tcp_udp_tunneling_overhead; 3729 if (mtuoffer != -1) { 3730 KASSERT(offer == -1, ("%s: conflict", __func__)); 3731 offer = mtuoffer - min_protoh; 3732 } 3733 3734 /* Initialize. */ 3735 #ifdef INET6 3736 if (isipv6) { 3737 maxmtu = tcp_maxmtu6(&inp->inp_inc, cap); 3738 tp->t_maxseg = V_tcp_v6mssdflt; 3739 } 3740 #endif 3741 #if defined(INET) && defined(INET6) 3742 else 3743 #endif 3744 #ifdef INET 3745 { 3746 maxmtu = tcp_maxmtu(&inp->inp_inc, cap); 3747 tp->t_maxseg = V_tcp_mssdflt; 3748 } 3749 #endif 3750 3751 /* 3752 * No route to sender, stay with default mss and return. 3753 */ 3754 if (maxmtu == 0) { 3755 /* 3756 * In case we return early we need to initialize metrics 3757 * to a defined state as tcp_hc_get() would do for us 3758 * if there was no cache hit. 3759 */ 3760 if (metricptr != NULL) 3761 bzero(metricptr, sizeof(struct hc_metrics_lite)); 3762 return; 3763 } 3764 3765 /* What have we got? */ 3766 switch (offer) { 3767 case 0: 3768 /* 3769 * Offer == 0 means that there was no MSS on the SYN 3770 * segment, in this case we use tcp_mssdflt as 3771 * already assigned to t_maxseg above. 3772 */ 3773 offer = tp->t_maxseg; 3774 break; 3775 3776 case -1: 3777 /* 3778 * Offer == -1 means that we didn't receive SYN yet. 3779 */ 3780 /* FALLTHROUGH */ 3781 3782 default: 3783 /* 3784 * Prevent DoS attack with too small MSS. Round up 3785 * to at least minmss. 3786 */ 3787 offer = max(offer, V_tcp_minmss); 3788 } 3789 3790 /* 3791 * rmx information is now retrieved from tcp_hostcache. 3792 */ 3793 tcp_hc_get(&inp->inp_inc, &metrics); 3794 if (metricptr != NULL) 3795 bcopy(&metrics, metricptr, sizeof(struct hc_metrics_lite)); 3796 3797 /* 3798 * If there's a discovered mtu in tcp hostcache, use it. 3799 * Else, use the link mtu. 3800 */ 3801 if (metrics.rmx_mtu) 3802 mss = min(metrics.rmx_mtu, maxmtu) - min_protoh; 3803 else { 3804 #ifdef INET6 3805 if (isipv6) { 3806 mss = maxmtu - min_protoh; 3807 if (!V_path_mtu_discovery && 3808 !in6_localaddr(&inp->in6p_faddr)) 3809 mss = min(mss, V_tcp_v6mssdflt); 3810 } 3811 #endif 3812 #if defined(INET) && defined(INET6) 3813 else 3814 #endif 3815 #ifdef INET 3816 { 3817 mss = maxmtu - min_protoh; 3818 if (!V_path_mtu_discovery && 3819 !in_localaddr(inp->inp_faddr)) 3820 mss = min(mss, V_tcp_mssdflt); 3821 } 3822 #endif 3823 /* 3824 * XXX - The above conditional (mss = maxmtu - min_protoh) 3825 * probably violates the TCP spec. 3826 * The problem is that, since we don't know the 3827 * other end's MSS, we are supposed to use a conservative 3828 * default. But, if we do that, then MTU discovery will 3829 * never actually take place, because the conservative 3830 * default is much less than the MTUs typically seen 3831 * on the Internet today. For the moment, we'll sweep 3832 * this under the carpet. 3833 * 3834 * The conservative default might not actually be a problem 3835 * if the only case this occurs is when sending an initial 3836 * SYN with options and data to a host we've never talked 3837 * to before. Then, they will reply with an MSS value which 3838 * will get recorded and the new parameters should get 3839 * recomputed. For Further Study. 3840 */ 3841 } 3842 mss = min(mss, offer); 3843 3844 /* 3845 * Sanity check: make sure that maxseg will be large 3846 * enough to allow some data on segments even if the 3847 * all the option space is used (40bytes). Otherwise 3848 * funny things may happen in tcp_output. 3849 * 3850 * XXXGL: shouldn't we reserve space for IP/IPv6 options? 3851 */ 3852 mss = max(mss, 64); 3853 3854 tp->t_maxseg = mss; 3855 } 3856 3857 void 3858 tcp_mss(struct tcpcb *tp, int offer) 3859 { 3860 int mss; 3861 uint32_t bufsize; 3862 struct inpcb *inp = tptoinpcb(tp); 3863 struct socket *so; 3864 struct hc_metrics_lite metrics; 3865 struct tcp_ifcap cap; 3866 3867 KASSERT(tp != NULL, ("%s: tp == NULL", __func__)); 3868 3869 bzero(&cap, sizeof(cap)); 3870 tcp_mss_update(tp, offer, -1, &metrics, &cap); 3871 3872 mss = tp->t_maxseg; 3873 3874 /* 3875 * If there's a pipesize, change the socket buffer to that size, 3876 * don't change if sb_hiwat is different than default (then it 3877 * has been changed on purpose with setsockopt). 3878 * Make the socket buffers an integral number of mss units; 3879 * if the mss is larger than the socket buffer, decrease the mss. 3880 */ 3881 so = inp->inp_socket; 3882 SOCKBUF_LOCK(&so->so_snd); 3883 if ((so->so_snd.sb_hiwat == V_tcp_sendspace) && metrics.rmx_sendpipe) 3884 bufsize = metrics.rmx_sendpipe; 3885 else 3886 bufsize = so->so_snd.sb_hiwat; 3887 if (bufsize < mss) 3888 mss = bufsize; 3889 else { 3890 bufsize = roundup(bufsize, mss); 3891 if (bufsize > sb_max) 3892 bufsize = sb_max; 3893 if (bufsize > so->so_snd.sb_hiwat) 3894 (void)sbreserve_locked(so, SO_SND, bufsize, NULL); 3895 } 3896 SOCKBUF_UNLOCK(&so->so_snd); 3897 /* 3898 * Sanity check: make sure that maxseg will be large 3899 * enough to allow some data on segments even if the 3900 * all the option space is used (40bytes). Otherwise 3901 * funny things may happen in tcp_output. 3902 * 3903 * XXXGL: shouldn't we reserve space for IP/IPv6 options? 3904 */ 3905 tp->t_maxseg = max(mss, 64); 3906 3907 SOCKBUF_LOCK(&so->so_rcv); 3908 if ((so->so_rcv.sb_hiwat == V_tcp_recvspace) && metrics.rmx_recvpipe) 3909 bufsize = metrics.rmx_recvpipe; 3910 else 3911 bufsize = so->so_rcv.sb_hiwat; 3912 if (bufsize > mss) { 3913 bufsize = roundup(bufsize, mss); 3914 if (bufsize > sb_max) 3915 bufsize = sb_max; 3916 if (bufsize > so->so_rcv.sb_hiwat) 3917 (void)sbreserve_locked(so, SO_RCV, bufsize, NULL); 3918 } 3919 SOCKBUF_UNLOCK(&so->so_rcv); 3920 3921 /* Check the interface for TSO capabilities. */ 3922 if (cap.ifcap & CSUM_TSO) { 3923 tp->t_flags |= TF_TSO; 3924 tp->t_tsomax = cap.tsomax; 3925 tp->t_tsomaxsegcount = cap.tsomaxsegcount; 3926 tp->t_tsomaxsegsize = cap.tsomaxsegsize; 3927 } 3928 } 3929 3930 /* 3931 * Determine the MSS option to send on an outgoing SYN. 3932 */ 3933 int 3934 tcp_mssopt(struct in_conninfo *inc) 3935 { 3936 int mss = 0; 3937 uint32_t thcmtu = 0; 3938 uint32_t maxmtu = 0; 3939 size_t min_protoh; 3940 3941 KASSERT(inc != NULL, ("tcp_mssopt with NULL in_conninfo pointer")); 3942 3943 #ifdef INET6 3944 if (inc->inc_flags & INC_ISIPV6) { 3945 mss = V_tcp_v6mssdflt; 3946 maxmtu = tcp_maxmtu6(inc, NULL); 3947 min_protoh = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 3948 } 3949 #endif 3950 #if defined(INET) && defined(INET6) 3951 else 3952 #endif 3953 #ifdef INET 3954 { 3955 mss = V_tcp_mssdflt; 3956 maxmtu = tcp_maxmtu(inc, NULL); 3957 min_protoh = sizeof(struct tcpiphdr); 3958 } 3959 #endif 3960 #if defined(INET6) || defined(INET) 3961 thcmtu = tcp_hc_getmtu(inc); /* IPv4 and IPv6 */ 3962 #endif 3963 3964 if (maxmtu && thcmtu) 3965 mss = min(maxmtu, thcmtu) - min_protoh; 3966 else if (maxmtu || thcmtu) 3967 mss = max(maxmtu, thcmtu) - min_protoh; 3968 3969 return (mss); 3970 } 3971 3972 void 3973 tcp_do_prr_ack(struct tcpcb *tp, struct tcphdr *th, struct tcpopt *to, 3974 sackstatus_t sack_changed, u_int *maxsegp) 3975 { 3976 int snd_cnt = 0, limit = 0, del_data = 0, pipe = 0; 3977 u_int maxseg; 3978 3979 INP_WLOCK_ASSERT(tptoinpcb(tp)); 3980 3981 if (*maxsegp == 0) { 3982 *maxsegp = tcp_maxseg(tp); 3983 } 3984 maxseg = *maxsegp; 3985 /* 3986 * Compute the amount of data that this ACK is indicating 3987 * (del_data) and an estimate of how many bytes are in the 3988 * network. 3989 */ 3990 if (tcp_is_sack_recovery(tp, to) || 3991 (IN_CONGRECOVERY(tp->t_flags) && 3992 !IN_FASTRECOVERY(tp->t_flags))) { 3993 del_data = tp->sackhint.delivered_data; 3994 if (V_tcp_do_newsack) 3995 pipe = tcp_compute_pipe(tp); 3996 else 3997 pipe = (tp->snd_nxt - tp->snd_fack) + 3998 tp->sackhint.sack_bytes_rexmit; 3999 } else { 4000 if (tp->sackhint.prr_delivered < (tcprexmtthresh * maxseg + 4001 tp->snd_recover - tp->snd_una)) { 4002 del_data = maxseg; 4003 } 4004 pipe = imax(0, tp->snd_max - tp->snd_una - 4005 imin(INT_MAX / 65536, tp->t_dupacks) * maxseg); 4006 } 4007 tp->sackhint.prr_delivered += del_data; 4008 /* 4009 * Proportional Rate Reduction 4010 */ 4011 if (pipe >= tp->snd_ssthresh) { 4012 if (tp->sackhint.recover_fs == 0) 4013 tp->sackhint.recover_fs = 4014 imax(1, tp->snd_nxt - tp->snd_una); 4015 snd_cnt = howmany((long)tp->sackhint.prr_delivered * 4016 tp->snd_ssthresh, tp->sackhint.recover_fs) - 4017 tp->sackhint.prr_out + maxseg - 1; 4018 } else { 4019 /* 4020 * PRR 6937bis heuristic: 4021 * - A partial ack without SACK block beneath snd_recover 4022 * indicates further loss. 4023 * - An SACK scoreboard update adding a new hole indicates 4024 * further loss, so be conservative and send at most one 4025 * segment. 4026 * - Prevent ACK splitting attacks, by being conservative 4027 * when no new data is acked. 4028 */ 4029 if ((sack_changed == SACK_NEWLOSS) || (del_data == 0)) { 4030 limit = tp->sackhint.prr_delivered - 4031 tp->sackhint.prr_out; 4032 } else { 4033 limit = imax(tp->sackhint.prr_delivered - 4034 tp->sackhint.prr_out, del_data) + 4035 maxseg; 4036 } 4037 snd_cnt = imin((tp->snd_ssthresh - pipe), limit); 4038 } 4039 snd_cnt = imax(snd_cnt, 0) / maxseg; 4040 /* 4041 * Send snd_cnt new data into the network in response to this ack. 4042 * If there is going to be a SACK retransmission, adjust snd_cwnd 4043 * accordingly. 4044 */ 4045 if (IN_FASTRECOVERY(tp->t_flags)) { 4046 if (tcp_is_sack_recovery(tp, to)) { 4047 tp->snd_cwnd = tp->snd_nxt - tp->snd_recover + 4048 tp->sackhint.sack_bytes_rexmit + 4049 (snd_cnt * maxseg); 4050 } else { 4051 tp->snd_cwnd = (tp->snd_max - tp->snd_una) + 4052 (snd_cnt * maxseg); 4053 } 4054 } else if (IN_CONGRECOVERY(tp->t_flags)) { 4055 tp->snd_cwnd = pipe - del_data + (snd_cnt * maxseg); 4056 } 4057 tp->snd_cwnd = imax(maxseg, tp->snd_cwnd); 4058 } 4059 4060 /* 4061 * On a partial ack arrives, force the retransmission of the 4062 * next unacknowledged segment. Do not clear tp->t_dupacks. 4063 * By setting snd_nxt to ti_ack, this forces retransmission timer to 4064 * be started again. 4065 */ 4066 void 4067 tcp_newreno_partial_ack(struct tcpcb *tp, struct tcphdr *th) 4068 { 4069 tcp_seq onxt = tp->snd_nxt; 4070 uint32_t ocwnd = tp->snd_cwnd; 4071 u_int maxseg = tcp_maxseg(tp); 4072 4073 INP_WLOCK_ASSERT(tptoinpcb(tp)); 4074 4075 tcp_timer_activate(tp, TT_REXMT, 0); 4076 tp->t_rtttime = 0; 4077 tp->snd_nxt = th->th_ack; 4078 /* 4079 * Set snd_cwnd to one segment beyond acknowledged offset. 4080 * (tp->snd_una has not yet been updated when this function is called.) 4081 */ 4082 tp->snd_cwnd = maxseg + BYTES_THIS_ACK(tp, th); 4083 tp->t_flags |= TF_ACKNOW; 4084 (void) tcp_output(tp); 4085 tp->snd_cwnd = ocwnd; 4086 if (SEQ_GT(onxt, tp->snd_nxt)) 4087 tp->snd_nxt = onxt; 4088 /* 4089 * Partial window deflation. Relies on fact that tp->snd_una 4090 * not updated yet. 4091 */ 4092 if (tp->snd_cwnd > BYTES_THIS_ACK(tp, th)) 4093 tp->snd_cwnd -= BYTES_THIS_ACK(tp, th); 4094 else 4095 tp->snd_cwnd = 0; 4096 tp->snd_cwnd += maxseg; 4097 } 4098 4099 int 4100 tcp_compute_pipe(struct tcpcb *tp) 4101 { 4102 if (tp->t_fb->tfb_compute_pipe == NULL) { 4103 return (tp->snd_max - tp->snd_una + 4104 tp->sackhint.sack_bytes_rexmit - 4105 tp->sackhint.sacked_bytes - 4106 tp->sackhint.lost_bytes); 4107 } else { 4108 return((*tp->t_fb->tfb_compute_pipe)(tp)); 4109 } 4110 } 4111 4112 uint32_t 4113 tcp_compute_initwnd(uint32_t maxseg) 4114 { 4115 /* 4116 * Calculate the Initial Window, also used as Restart Window 4117 * 4118 * RFC5681 Section 3.1 specifies the default conservative values. 4119 * RFC3390 specifies slightly more aggressive values. 4120 * RFC6928 increases it to ten segments. 4121 * Support for user specified value for initial flight size. 4122 */ 4123 if (V_tcp_initcwnd_segments) 4124 return min(V_tcp_initcwnd_segments * maxseg, 4125 max(2 * maxseg, V_tcp_initcwnd_segments * 1460)); 4126 else if (V_tcp_do_rfc3390) 4127 return min(4 * maxseg, max(2 * maxseg, 4380)); 4128 else { 4129 /* Per RFC5681 Section 3.1 */ 4130 if (maxseg > 2190) 4131 return (2 * maxseg); 4132 else if (maxseg > 1095) 4133 return (3 * maxseg); 4134 else 4135 return (4 * maxseg); 4136 } 4137 } 4138