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_insecure_ack) = 0; 206 SYSCTL_INT(_net_inet_tcp, OID_AUTO, insecure_ack, CTLFLAG_VNET | CTLFLAG_RW, 207 &VNET_NAME(tcp_insecure_ack), 0, 208 "Follow RFC793 criteria for validating SEG.ACK"); 209 210 VNET_DEFINE(int, tcp_recvspace) = 1024*64; 211 #define V_tcp_recvspace VNET(tcp_recvspace) 212 SYSCTL_INT(_net_inet_tcp, TCPCTL_RECVSPACE, recvspace, CTLFLAG_VNET | CTLFLAG_RW, 213 &VNET_NAME(tcp_recvspace), 0, "Initial receive socket buffer size"); 214 215 VNET_DEFINE(int, tcp_do_autorcvbuf) = 1; 216 SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_auto, CTLFLAG_VNET | CTLFLAG_RW, 217 &VNET_NAME(tcp_do_autorcvbuf), 0, 218 "Enable automatic receive buffer sizing"); 219 220 VNET_DEFINE(int, tcp_autorcvbuf_max) = 2*1024*1024; 221 SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_max, CTLFLAG_VNET | CTLFLAG_RW, 222 &VNET_NAME(tcp_autorcvbuf_max), 0, 223 "Max size of automatic receive buffer"); 224 225 VNET_DEFINE(struct inpcbinfo, tcbinfo); 226 227 /* 228 * TCP statistics are stored in an array of counter(9)s, which size matches 229 * size of struct tcpstat. TCP running connection count is a regular array. 230 */ 231 VNET_PCPUSTAT_DEFINE(struct tcpstat, tcpstat); 232 SYSCTL_VNET_PCPUSTAT(_net_inet_tcp, TCPCTL_STATS, stats, struct tcpstat, 233 tcpstat, "TCP statistics (struct tcpstat, netinet/tcp_var.h)"); 234 VNET_DEFINE(counter_u64_t, tcps_states[TCP_NSTATES]); 235 SYSCTL_COUNTER_U64_ARRAY(_net_inet_tcp, TCPCTL_STATES, states, CTLFLAG_RD | 236 CTLFLAG_VNET, &VNET_NAME(tcps_states)[0], TCP_NSTATES, 237 "TCP connection counts by TCP state"); 238 239 /* 240 * Kernel module interface for updating tcpstat. The first argument is an index 241 * into tcpstat treated as an array. 242 */ 243 void 244 kmod_tcpstat_add(int statnum, int val) 245 { 246 247 counter_u64_add(VNET(tcpstat)[statnum], val); 248 } 249 250 /* 251 * Make sure that we only start a SACK loss recovery when 252 * receiving a duplicate ACK with a SACK block, and also 253 * complete SACK loss recovery in case the other end 254 * reneges. 255 */ 256 static bool inline 257 tcp_is_sack_recovery(struct tcpcb *tp, struct tcpopt *to) 258 { 259 return ((tp->t_flags & TF_SACK_PERMIT) && 260 ((to->to_flags & TOF_SACK) || 261 (!TAILQ_EMPTY(&tp->snd_holes)))); 262 } 263 264 #ifdef TCP_HHOOK 265 /* 266 * Wrapper for the TCP established input helper hook. 267 */ 268 void 269 hhook_run_tcp_est_in(struct tcpcb *tp, struct tcphdr *th, struct tcpopt *to) 270 { 271 struct tcp_hhook_data hhook_data; 272 273 if (V_tcp_hhh[HHOOK_TCP_EST_IN]->hhh_nhooks > 0) { 274 hhook_data.tp = tp; 275 hhook_data.th = th; 276 hhook_data.to = to; 277 278 hhook_run_hooks(V_tcp_hhh[HHOOK_TCP_EST_IN], &hhook_data, 279 &tp->t_osd); 280 } 281 } 282 #endif 283 284 /* 285 * CC wrapper hook functions 286 */ 287 void 288 cc_ack_received(struct tcpcb *tp, struct tcphdr *th, uint16_t nsegs, 289 uint16_t type) 290 { 291 #ifdef STATS 292 int32_t gput; 293 #endif 294 295 INP_WLOCK_ASSERT(tptoinpcb(tp)); 296 297 tp->t_ccv.nsegs = nsegs; 298 tp->t_ccv.bytes_this_ack = BYTES_THIS_ACK(tp, th); 299 if ((!V_tcp_do_newcwv && (tp->snd_cwnd <= tp->snd_wnd)) || 300 (V_tcp_do_newcwv && (tp->snd_cwnd <= tp->snd_wnd) && 301 (tp->snd_cwnd < (tcp_compute_pipe(tp) * 2)))) 302 tp->t_ccv.flags |= CCF_CWND_LIMITED; 303 else 304 tp->t_ccv.flags &= ~CCF_CWND_LIMITED; 305 306 if (type == CC_ACK) { 307 #ifdef STATS 308 stats_voi_update_abs_s32(tp->t_stats, VOI_TCP_CALCFRWINDIFF, 309 ((int32_t)tp->snd_cwnd) - tp->snd_wnd); 310 if (!IN_RECOVERY(tp->t_flags)) 311 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_ACKLEN, 312 tp->t_ccv.bytes_this_ack / (tcp_maxseg(tp) * nsegs)); 313 if ((tp->t_flags & TF_GPUTINPROG) && 314 SEQ_GEQ(th->th_ack, tp->gput_ack)) { 315 /* 316 * Compute goodput in bits per millisecond. 317 */ 318 gput = (((int64_t)SEQ_SUB(th->th_ack, tp->gput_seq)) << 3) / 319 max(1, tcp_ts_getticks() - tp->gput_ts); 320 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_GPUT, 321 gput); 322 /* 323 * XXXLAS: This is a temporary hack, and should be 324 * chained off VOI_TCP_GPUT when stats(9) grows an API 325 * to deal with chained VOIs. 326 */ 327 if (tp->t_stats_gput_prev > 0) 328 stats_voi_update_abs_s32(tp->t_stats, 329 VOI_TCP_GPUT_ND, 330 ((gput - tp->t_stats_gput_prev) * 100) / 331 tp->t_stats_gput_prev); 332 tp->t_flags &= ~TF_GPUTINPROG; 333 tp->t_stats_gput_prev = gput; 334 } 335 #endif /* STATS */ 336 if (tp->snd_cwnd > tp->snd_ssthresh) { 337 tp->t_bytes_acked += tp->t_ccv.bytes_this_ack; 338 if (tp->t_bytes_acked >= tp->snd_cwnd) { 339 tp->t_bytes_acked -= tp->snd_cwnd; 340 tp->t_ccv.flags |= CCF_ABC_SENTAWND; 341 } 342 } else { 343 tp->t_ccv.flags &= ~CCF_ABC_SENTAWND; 344 tp->t_bytes_acked = 0; 345 } 346 } 347 348 if (CC_ALGO(tp)->ack_received != NULL) { 349 /* XXXLAS: Find a way to live without this */ 350 tp->t_ccv.curack = th->th_ack; 351 CC_ALGO(tp)->ack_received(&tp->t_ccv, type); 352 } 353 #ifdef STATS 354 stats_voi_update_abs_ulong(tp->t_stats, VOI_TCP_LCWIN, tp->snd_cwnd); 355 #endif 356 } 357 358 void 359 cc_conn_init(struct tcpcb *tp) 360 { 361 struct hc_metrics_lite metrics; 362 struct inpcb *inp = tptoinpcb(tp); 363 u_int maxseg; 364 int rtt; 365 366 INP_WLOCK_ASSERT(inp); 367 368 tcp_hc_get(&inp->inp_inc, &metrics); 369 maxseg = tcp_maxseg(tp); 370 371 if (tp->t_srtt == 0 && (rtt = metrics.rmx_rtt)) { 372 tp->t_srtt = rtt; 373 TCPSTAT_INC(tcps_usedrtt); 374 if (metrics.rmx_rttvar) { 375 tp->t_rttvar = metrics.rmx_rttvar; 376 TCPSTAT_INC(tcps_usedrttvar); 377 } else { 378 /* default variation is +- 1 rtt */ 379 tp->t_rttvar = 380 tp->t_srtt * TCP_RTTVAR_SCALE / TCP_RTT_SCALE; 381 } 382 TCPT_RANGESET(tp->t_rxtcur, 383 ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1, 384 tp->t_rttmin, TCPTV_REXMTMAX); 385 } 386 if (metrics.rmx_ssthresh) { 387 /* 388 * There's some sort of gateway or interface 389 * buffer limit on the path. Use this to set 390 * the slow start threshold, but set the 391 * threshold to no less than 2*mss. 392 */ 393 tp->snd_ssthresh = max(2 * maxseg, metrics.rmx_ssthresh); 394 TCPSTAT_INC(tcps_usedssthresh); 395 } 396 397 /* 398 * Set the initial slow-start flight size. 399 * 400 * If a SYN or SYN/ACK was lost and retransmitted, we have to 401 * reduce the initial CWND to one segment as congestion is likely 402 * requiring us to be cautious. 403 */ 404 if (tp->snd_cwnd == 1) 405 tp->snd_cwnd = maxseg; /* SYN(-ACK) lost */ 406 else 407 tp->snd_cwnd = tcp_compute_initwnd(maxseg); 408 409 if (CC_ALGO(tp)->conn_init != NULL) 410 CC_ALGO(tp)->conn_init(&tp->t_ccv); 411 } 412 413 void inline 414 cc_cong_signal(struct tcpcb *tp, struct tcphdr *th, uint32_t type) 415 { 416 INP_WLOCK_ASSERT(tptoinpcb(tp)); 417 418 #ifdef STATS 419 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_CSIG, type); 420 #endif 421 422 switch(type) { 423 case CC_NDUPACK: 424 if (!IN_FASTRECOVERY(tp->t_flags)) { 425 tp->snd_recover = tp->snd_max; 426 if (tp->t_flags2 & TF2_ECN_PERMIT) 427 tp->t_flags2 |= TF2_ECN_SND_CWR; 428 } 429 break; 430 case CC_ECN: 431 if (!IN_CONGRECOVERY(tp->t_flags) || 432 /* 433 * Allow ECN reaction on ACK to CWR, if 434 * that data segment was also CE marked. 435 */ 436 SEQ_GEQ(th->th_ack, tp->snd_recover)) { 437 EXIT_CONGRECOVERY(tp->t_flags); 438 TCPSTAT_INC(tcps_ecn_rcwnd); 439 tp->snd_recover = tp->snd_max + 1; 440 if (tp->t_flags2 & TF2_ECN_PERMIT) 441 tp->t_flags2 |= TF2_ECN_SND_CWR; 442 } 443 break; 444 case CC_RTO: 445 tp->t_dupacks = 0; 446 tp->t_bytes_acked = 0; 447 if ((tp->t_rxtshift > 1) || 448 !((tp->t_flags & TF_SACK_PERMIT) && 449 (!TAILQ_EMPTY(&tp->snd_holes)))) 450 EXIT_RECOVERY(tp->t_flags); 451 if (tp->t_flags2 & TF2_ECN_PERMIT) 452 tp->t_flags2 |= TF2_ECN_SND_CWR; 453 break; 454 case CC_RTO_ERR: 455 TCPSTAT_INC(tcps_sndrexmitbad); 456 /* RTO was unnecessary, so reset everything. */ 457 tp->snd_cwnd = tp->snd_cwnd_prev; 458 tp->snd_ssthresh = tp->snd_ssthresh_prev; 459 tp->snd_recover = tp->snd_recover_prev; 460 if (tp->t_flags & TF_WASFRECOVERY) 461 ENTER_FASTRECOVERY(tp->t_flags); 462 if (tp->t_flags & TF_WASCRECOVERY) 463 ENTER_CONGRECOVERY(tp->t_flags); 464 tp->snd_nxt = tp->snd_max; 465 tp->t_flags &= ~TF_PREVVALID; 466 tp->t_badrxtwin = 0; 467 break; 468 } 469 if (SEQ_LT(tp->snd_fack, tp->snd_una) || 470 SEQ_GT(tp->snd_fack, tp->snd_max)) { 471 tp->snd_fack = tp->snd_una; 472 } 473 474 if (CC_ALGO(tp)->cong_signal != NULL) { 475 if (th != NULL) 476 tp->t_ccv.curack = th->th_ack; 477 CC_ALGO(tp)->cong_signal(&tp->t_ccv, type); 478 } 479 } 480 481 void inline 482 cc_post_recovery(struct tcpcb *tp, struct tcphdr *th) 483 { 484 INP_WLOCK_ASSERT(tptoinpcb(tp)); 485 486 if (CC_ALGO(tp)->post_recovery != NULL) { 487 if (SEQ_LT(tp->snd_fack, th->th_ack) || 488 SEQ_GT(tp->snd_fack, tp->snd_max)) { 489 tp->snd_fack = th->th_ack; 490 } 491 tp->t_ccv.curack = th->th_ack; 492 CC_ALGO(tp)->post_recovery(&tp->t_ccv); 493 } 494 EXIT_RECOVERY(tp->t_flags); 495 496 tp->t_bytes_acked = 0; 497 tp->sackhint.delivered_data = 0; 498 tp->sackhint.prr_delivered = 0; 499 tp->sackhint.prr_out = 0; 500 } 501 502 /* 503 * Indicate whether this ack should be delayed. We can delay the ack if 504 * following conditions are met: 505 * - There is no delayed ack timer in progress. 506 * - Our last ack wasn't a 0-sized window. We never want to delay 507 * the ack that opens up a 0-sized window. 508 * - LRO wasn't used for this segment. We make sure by checking that the 509 * segment size is not larger than the MSS. 510 */ 511 #define DELAY_ACK(tp, tlen) \ 512 ((!tcp_timer_active(tp, TT_DELACK) && \ 513 (tp->t_flags & TF_RXWIN0SENT) == 0) && \ 514 (tlen <= tp->t_maxseg) && \ 515 (V_tcp_delack_enabled || (tp->t_flags & TF_NEEDSYN))) 516 517 void inline 518 cc_ecnpkt_handler_flags(struct tcpcb *tp, uint16_t flags, uint8_t iptos) 519 { 520 INP_WLOCK_ASSERT(tptoinpcb(tp)); 521 522 if (CC_ALGO(tp)->ecnpkt_handler != NULL) { 523 switch (iptos & IPTOS_ECN_MASK) { 524 case IPTOS_ECN_CE: 525 tp->t_ccv.flags |= CCF_IPHDR_CE; 526 break; 527 case IPTOS_ECN_ECT0: 528 /* FALLTHROUGH */ 529 case IPTOS_ECN_ECT1: 530 /* FALLTHROUGH */ 531 case IPTOS_ECN_NOTECT: 532 tp->t_ccv.flags &= ~CCF_IPHDR_CE; 533 break; 534 } 535 536 if (flags & TH_CWR) 537 tp->t_ccv.flags |= CCF_TCPHDR_CWR; 538 else 539 tp->t_ccv.flags &= ~CCF_TCPHDR_CWR; 540 541 CC_ALGO(tp)->ecnpkt_handler(&tp->t_ccv); 542 543 if (tp->t_ccv.flags & CCF_ACKNOW) { 544 tcp_timer_activate(tp, TT_DELACK, tcp_delacktime); 545 tp->t_flags |= TF_ACKNOW; 546 } 547 } 548 } 549 550 void inline 551 cc_ecnpkt_handler(struct tcpcb *tp, struct tcphdr *th, uint8_t iptos) 552 { 553 cc_ecnpkt_handler_flags(tp, tcp_get_flags(th), iptos); 554 } 555 556 /* 557 * TCP input handling is split into multiple parts: 558 * tcp6_input is a thin wrapper around tcp_input for the extended 559 * ip6_protox[] call format in ip6_input 560 * tcp_input handles primary segment validation, inpcb lookup and 561 * SYN processing on listen sockets 562 * tcp_do_segment processes the ACK and text of the segment for 563 * establishing, established and closing connections 564 */ 565 #ifdef INET6 566 int 567 tcp6_input_with_port(struct mbuf **mp, int *offp, int proto, uint16_t port) 568 { 569 struct mbuf *m; 570 struct in6_ifaddr *ia6; 571 struct ip6_hdr *ip6; 572 573 m = *mp; 574 if (m->m_len < *offp + sizeof(struct tcphdr)) { 575 m = m_pullup(m, *offp + sizeof(struct tcphdr)); 576 if (m == NULL) { 577 *mp = m; 578 TCPSTAT_INC(tcps_rcvshort); 579 return (IPPROTO_DONE); 580 } 581 } 582 583 /* 584 * draft-itojun-ipv6-tcp-to-anycast 585 * better place to put this in? 586 */ 587 ip6 = mtod(m, struct ip6_hdr *); 588 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false); 589 if (ia6 && (ia6->ia6_flags & IN6_IFF_ANYCAST)) { 590 icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR, 591 (caddr_t)&ip6->ip6_dst - (caddr_t)ip6); 592 *mp = NULL; 593 return (IPPROTO_DONE); 594 } 595 596 *mp = m; 597 return (tcp_input_with_port(mp, offp, proto, port)); 598 } 599 600 int 601 tcp6_input(struct mbuf **mp, int *offp, int proto) 602 { 603 604 return(tcp6_input_with_port(mp, offp, proto, 0)); 605 } 606 #endif /* INET6 */ 607 608 int 609 tcp_input_with_port(struct mbuf **mp, int *offp, int proto, uint16_t port) 610 { 611 struct mbuf *m = *mp; 612 struct tcphdr *th = NULL; 613 struct ip *ip = NULL; 614 struct inpcb *inp = NULL; 615 struct tcpcb *tp = NULL; 616 struct socket *so = NULL; 617 u_char *optp = NULL; 618 int off0; 619 int optlen = 0; 620 #ifdef INET 621 int len; 622 uint8_t ipttl; 623 #endif 624 int tlen = 0, off; 625 int drop_hdrlen; 626 int thflags; 627 int rstreason = 0; /* For badport_bandlim accounting purposes */ 628 int lookupflag; 629 uint8_t iptos; 630 struct m_tag *fwd_tag = NULL; 631 #ifdef INET6 632 struct ip6_hdr *ip6 = NULL; 633 int isipv6; 634 #else 635 const void *ip6 = NULL; 636 #endif /* INET6 */ 637 struct tcpopt to; /* options in this segment */ 638 char *s = NULL; /* address and port logging */ 639 640 NET_EPOCH_ASSERT(); 641 642 #ifdef INET6 643 isipv6 = (mtod(m, struct ip *)->ip_v == 6) ? 1 : 0; 644 #endif 645 646 off0 = *offp; 647 m = *mp; 648 *mp = NULL; 649 to.to_flags = 0; 650 TCPSTAT_INC(tcps_rcvtotal); 651 652 m->m_pkthdr.tcp_tun_port = port; 653 #ifdef INET6 654 if (isipv6) { 655 ip6 = mtod(m, struct ip6_hdr *); 656 th = (struct tcphdr *)((caddr_t)ip6 + off0); 657 tlen = sizeof(*ip6) + ntohs(ip6->ip6_plen) - off0; 658 if (port) 659 goto skip6_csum; 660 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID_IPV6) { 661 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 662 th->th_sum = m->m_pkthdr.csum_data; 663 else 664 th->th_sum = in6_cksum_pseudo(ip6, tlen, 665 IPPROTO_TCP, m->m_pkthdr.csum_data); 666 th->th_sum ^= 0xffff; 667 } else 668 th->th_sum = in6_cksum(m, IPPROTO_TCP, off0, tlen); 669 if (th->th_sum) { 670 TCPSTAT_INC(tcps_rcvbadsum); 671 goto drop; 672 } 673 skip6_csum: 674 /* 675 * Be proactive about unspecified IPv6 address in source. 676 * As we use all-zero to indicate unbounded/unconnected pcb, 677 * unspecified IPv6 address can be used to confuse us. 678 * 679 * Note that packets with unspecified IPv6 destination is 680 * already dropped in ip6_input. 681 */ 682 KASSERT(!IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_dst), 683 ("%s: unspecified destination v6 address", __func__)); 684 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 685 IP6STAT_INC(ip6s_badscope); /* XXX */ 686 goto drop; 687 } 688 iptos = IPV6_TRAFFIC_CLASS(ip6); 689 } 690 #endif 691 #if defined(INET) && defined(INET6) 692 else 693 #endif 694 #ifdef INET 695 { 696 /* 697 * Get IP and TCP header together in first mbuf. 698 * Note: IP leaves IP header in first mbuf. 699 */ 700 if (off0 > sizeof (struct ip)) { 701 ip_stripoptions(m); 702 off0 = sizeof(struct ip); 703 } 704 if (m->m_len < sizeof (struct tcpiphdr)) { 705 if ((m = m_pullup(m, sizeof (struct tcpiphdr))) 706 == NULL) { 707 TCPSTAT_INC(tcps_rcvshort); 708 return (IPPROTO_DONE); 709 } 710 } 711 ip = mtod(m, struct ip *); 712 th = (struct tcphdr *)((caddr_t)ip + off0); 713 tlen = ntohs(ip->ip_len) - off0; 714 715 iptos = ip->ip_tos; 716 if (port) 717 goto skip_csum; 718 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) { 719 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 720 th->th_sum = m->m_pkthdr.csum_data; 721 else 722 th->th_sum = in_pseudo(ip->ip_src.s_addr, 723 ip->ip_dst.s_addr, 724 htonl(m->m_pkthdr.csum_data + tlen + 725 IPPROTO_TCP)); 726 th->th_sum ^= 0xffff; 727 } else { 728 struct ipovly *ipov = (struct ipovly *)ip; 729 730 /* 731 * Checksum extended TCP header and data. 732 */ 733 len = off0 + tlen; 734 ipttl = ip->ip_ttl; 735 bzero(ipov->ih_x1, sizeof(ipov->ih_x1)); 736 ipov->ih_len = htons(tlen); 737 th->th_sum = in_cksum(m, len); 738 /* Reset length for SDT probes. */ 739 ip->ip_len = htons(len); 740 /* Reset TOS bits */ 741 ip->ip_tos = iptos; 742 /* Re-initialization for later version check */ 743 ip->ip_ttl = ipttl; 744 ip->ip_v = IPVERSION; 745 ip->ip_hl = off0 >> 2; 746 } 747 skip_csum: 748 if (th->th_sum && (port == 0)) { 749 TCPSTAT_INC(tcps_rcvbadsum); 750 goto drop; 751 } 752 KASSERT(ip->ip_dst.s_addr != INADDR_ANY, 753 ("%s: unspecified destination v4 address", __func__)); 754 if (__predict_false(ip->ip_src.s_addr == INADDR_ANY)) { 755 IPSTAT_INC(ips_badaddr); 756 goto drop; 757 } 758 } 759 #endif /* INET */ 760 761 /* 762 * Check that TCP offset makes sense, 763 * pull out TCP options and adjust length. XXX 764 */ 765 off = th->th_off << 2; 766 if (off < sizeof (struct tcphdr) || off > tlen) { 767 TCPSTAT_INC(tcps_rcvbadoff); 768 goto drop; 769 } 770 tlen -= off; /* tlen is used instead of ti->ti_len */ 771 if (off > sizeof (struct tcphdr)) { 772 #ifdef INET6 773 if (isipv6) { 774 if (m->m_len < off0 + off) { 775 m = m_pullup(m, off0 + off); 776 if (m == NULL) { 777 TCPSTAT_INC(tcps_rcvshort); 778 return (IPPROTO_DONE); 779 } 780 } 781 ip6 = mtod(m, struct ip6_hdr *); 782 th = (struct tcphdr *)((caddr_t)ip6 + off0); 783 } 784 #endif 785 #if defined(INET) && defined(INET6) 786 else 787 #endif 788 #ifdef INET 789 { 790 if (m->m_len < sizeof(struct ip) + off) { 791 if ((m = m_pullup(m, sizeof (struct ip) + off)) 792 == NULL) { 793 TCPSTAT_INC(tcps_rcvshort); 794 return (IPPROTO_DONE); 795 } 796 ip = mtod(m, struct ip *); 797 th = (struct tcphdr *)((caddr_t)ip + off0); 798 } 799 } 800 #endif 801 optlen = off - sizeof (struct tcphdr); 802 optp = (u_char *)(th + 1); 803 } 804 thflags = tcp_get_flags(th); 805 806 /* 807 * Convert TCP protocol specific fields to host format. 808 */ 809 tcp_fields_to_host(th); 810 811 /* 812 * Delay dropping TCP, IP headers, IPv6 ext headers, and TCP options. 813 */ 814 drop_hdrlen = off0 + off; 815 816 /* 817 * Grab info from PACKET_TAG_IPFORWARD tag prepended to the chain. 818 */ 819 if ( 820 #ifdef INET6 821 (isipv6 && (m->m_flags & M_IP6_NEXTHOP)) 822 #ifdef INET 823 || (!isipv6 && (m->m_flags & M_IP_NEXTHOP)) 824 #endif 825 #endif 826 #if defined(INET) && !defined(INET6) 827 (m->m_flags & M_IP_NEXTHOP) 828 #endif 829 ) 830 fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL); 831 832 /* 833 * For initial SYN packets we don't need write lock on matching 834 * PCB, be it a listening one or a synchronized one. The packet 835 * shall not modify its state. 836 */ 837 lookupflag = INPLOOKUP_WILDCARD | 838 ((thflags & (TH_ACK|TH_SYN)) == TH_SYN ? 839 INPLOOKUP_RLOCKPCB : INPLOOKUP_WLOCKPCB); 840 findpcb: 841 tp = NULL; 842 #ifdef INET6 843 if (isipv6 && fwd_tag != NULL) { 844 struct sockaddr_in6 *next_hop6; 845 846 next_hop6 = (struct sockaddr_in6 *)(fwd_tag + 1); 847 /* 848 * Transparently forwarded. Pretend to be the destination. 849 * Already got one like this? 850 */ 851 inp = in6_pcblookup_mbuf(&V_tcbinfo, 852 &ip6->ip6_src, th->th_sport, &ip6->ip6_dst, th->th_dport, 853 lookupflag & ~INPLOOKUP_WILDCARD, m->m_pkthdr.rcvif, m); 854 if (!inp) { 855 /* 856 * It's new. Try to find the ambushing socket. 857 * Because we've rewritten the destination address, 858 * any hardware-generated hash is ignored. 859 */ 860 inp = in6_pcblookup(&V_tcbinfo, &ip6->ip6_src, 861 th->th_sport, &next_hop6->sin6_addr, 862 next_hop6->sin6_port ? ntohs(next_hop6->sin6_port) : 863 th->th_dport, lookupflag, m->m_pkthdr.rcvif); 864 } 865 } else if (isipv6) { 866 inp = in6_pcblookup_mbuf(&V_tcbinfo, &ip6->ip6_src, 867 th->th_sport, &ip6->ip6_dst, th->th_dport, lookupflag, 868 m->m_pkthdr.rcvif, m); 869 } 870 #endif /* INET6 */ 871 #if defined(INET6) && defined(INET) 872 else 873 #endif 874 #ifdef INET 875 if (fwd_tag != NULL) { 876 struct sockaddr_in *next_hop; 877 878 next_hop = (struct sockaddr_in *)(fwd_tag+1); 879 /* 880 * Transparently forwarded. Pretend to be the destination. 881 * already got one like this? 882 */ 883 inp = in_pcblookup_mbuf(&V_tcbinfo, ip->ip_src, th->th_sport, 884 ip->ip_dst, th->th_dport, lookupflag & ~INPLOOKUP_WILDCARD, 885 m->m_pkthdr.rcvif, m); 886 if (!inp) { 887 /* 888 * It's new. Try to find the ambushing socket. 889 * Because we've rewritten the destination address, 890 * any hardware-generated hash is ignored. 891 */ 892 inp = in_pcblookup(&V_tcbinfo, ip->ip_src, 893 th->th_sport, next_hop->sin_addr, 894 next_hop->sin_port ? ntohs(next_hop->sin_port) : 895 th->th_dport, lookupflag, m->m_pkthdr.rcvif); 896 } 897 } else 898 inp = in_pcblookup_mbuf(&V_tcbinfo, ip->ip_src, 899 th->th_sport, ip->ip_dst, th->th_dport, lookupflag, 900 m->m_pkthdr.rcvif, m); 901 #endif /* INET */ 902 903 /* 904 * If the INPCB does not exist then all data in the incoming 905 * segment is discarded and an appropriate RST is sent back. 906 * XXX MRT Send RST using which routing table? 907 */ 908 if (inp == NULL) { 909 if (rstreason != 0) { 910 /* We came here after second (safety) lookup. */ 911 MPASS((lookupflag & INPLOOKUP_WILDCARD) == 0); 912 goto dropwithreset; 913 } 914 /* 915 * Log communication attempts to ports that are not 916 * in use. 917 */ 918 if ((V_tcp_log_in_vain == 1 && (thflags & TH_SYN)) || 919 V_tcp_log_in_vain == 2) { 920 if ((s = tcp_log_vain(NULL, th, (void *)ip, ip6))) 921 log(LOG_INFO, "%s; %s: Connection attempt " 922 "to closed port\n", s, __func__); 923 } 924 rstreason = BANDLIM_RST_CLOSEDPORT; 925 goto dropwithreset; 926 } 927 INP_LOCK_ASSERT(inp); 928 929 if ((inp->inp_flowtype == M_HASHTYPE_NONE) && 930 !SOLISTENING(inp->inp_socket)) { 931 if (M_HASHTYPE_GET(m) != M_HASHTYPE_NONE) { 932 inp->inp_flowid = m->m_pkthdr.flowid; 933 inp->inp_flowtype = M_HASHTYPE_GET(m); 934 #ifdef RSS 935 } else { 936 /* assign flowid by software RSS hash */ 937 #ifdef INET6 938 if (isipv6) { 939 rss_proto_software_hash_v6(&inp->in6p_faddr, 940 &inp->in6p_laddr, 941 inp->inp_fport, 942 inp->inp_lport, 943 IPPROTO_TCP, 944 &inp->inp_flowid, 945 &inp->inp_flowtype); 946 } else 947 #endif /* INET6 */ 948 { 949 rss_proto_software_hash_v4(inp->inp_faddr, 950 inp->inp_laddr, 951 inp->inp_fport, 952 inp->inp_lport, 953 IPPROTO_TCP, 954 &inp->inp_flowid, 955 &inp->inp_flowtype); 956 } 957 #endif /* RSS */ 958 } 959 } 960 #if defined(IPSEC) || defined(IPSEC_SUPPORT) 961 #ifdef INET6 962 if (isipv6 && IPSEC_ENABLED(ipv6) && 963 IPSEC_CHECK_POLICY(ipv6, m, inp) != 0) { 964 goto dropunlock; 965 } 966 #ifdef INET 967 else 968 #endif 969 #endif /* INET6 */ 970 #ifdef INET 971 if (IPSEC_ENABLED(ipv4) && 972 IPSEC_CHECK_POLICY(ipv4, m, inp) != 0) { 973 goto dropunlock; 974 } 975 #endif /* INET */ 976 #endif /* IPSEC */ 977 978 /* 979 * Check the minimum TTL for socket. 980 */ 981 if (inp->inp_ip_minttl != 0) { 982 #ifdef INET6 983 if (isipv6) { 984 if (inp->inp_ip_minttl > ip6->ip6_hlim) 985 goto dropunlock; 986 } else 987 #endif 988 if (inp->inp_ip_minttl > ip->ip_ttl) 989 goto dropunlock; 990 } 991 992 tp = intotcpcb(inp); 993 switch (tp->t_state) { 994 case TCPS_TIME_WAIT: 995 /* 996 * A previous connection in TIMEWAIT state is supposed to catch 997 * stray or duplicate segments arriving late. If this segment 998 * was a legitimate new connection attempt, the old INPCB gets 999 * removed and we can try again to find a listening socket. 1000 */ 1001 tcp_dooptions(&to, optp, optlen, 1002 (thflags & TH_SYN) ? TO_SYN : 0); 1003 /* 1004 * tcp_twcheck unlocks the inp always, and frees the m if fails. 1005 */ 1006 if (tcp_twcheck(inp, &to, th, m, tlen)) 1007 goto findpcb; 1008 return (IPPROTO_DONE); 1009 case TCPS_CLOSED: 1010 /* 1011 * The TCPCB may no longer exist if the connection is winding 1012 * down or it is in the CLOSED state. Either way we drop the 1013 * segment and send an appropriate response. 1014 */ 1015 rstreason = BANDLIM_RST_CLOSEDPORT; 1016 goto dropwithreset; 1017 } 1018 1019 if ((tp->t_port != port) && (tp->t_state > TCPS_LISTEN)) { 1020 rstreason = BANDLIM_RST_CLOSEDPORT; 1021 goto dropwithreset; 1022 } 1023 1024 #ifdef TCP_OFFLOAD 1025 if (tp->t_flags & TF_TOE) { 1026 tcp_offload_input(tp, m); 1027 m = NULL; /* consumed by the TOE driver */ 1028 goto dropunlock; 1029 } 1030 #endif 1031 1032 #ifdef MAC 1033 if (mac_inpcb_check_deliver(inp, m)) 1034 goto dropunlock; 1035 #endif 1036 so = inp->inp_socket; 1037 KASSERT(so != NULL, ("%s: so == NULL", __func__)); 1038 /* 1039 * When the socket is accepting connections (the INPCB is in LISTEN 1040 * state) we look into the SYN cache if this is a new connection 1041 * attempt or the completion of a previous one. 1042 */ 1043 KASSERT(tp->t_state == TCPS_LISTEN || !SOLISTENING(so), 1044 ("%s: so accepting but tp %p not listening", __func__, tp)); 1045 if (tp->t_state == TCPS_LISTEN && SOLISTENING(so)) { 1046 struct in_conninfo inc; 1047 1048 bzero(&inc, sizeof(inc)); 1049 #ifdef INET6 1050 if (isipv6) { 1051 inc.inc_flags |= INC_ISIPV6; 1052 if (inp->inp_inc.inc_flags & INC_IPV6MINMTU) 1053 inc.inc_flags |= INC_IPV6MINMTU; 1054 inc.inc6_faddr = ip6->ip6_src; 1055 inc.inc6_laddr = ip6->ip6_dst; 1056 } else 1057 #endif 1058 { 1059 inc.inc_faddr = ip->ip_src; 1060 inc.inc_laddr = ip->ip_dst; 1061 } 1062 inc.inc_fport = th->th_sport; 1063 inc.inc_lport = th->th_dport; 1064 inc.inc_fibnum = so->so_fibnum; 1065 1066 /* 1067 * Check for an existing connection attempt in syncache if 1068 * the flag is only ACK. A successful lookup creates a new 1069 * socket appended to the listen queue in SYN_RECEIVED state. 1070 */ 1071 if ((thflags & (TH_RST|TH_ACK|TH_SYN)) == TH_ACK) { 1072 /* 1073 * Parse the TCP options here because 1074 * syncookies need access to the reflected 1075 * timestamp. 1076 */ 1077 tcp_dooptions(&to, optp, optlen, 0); 1078 /* 1079 * NB: syncache_expand() doesn't unlock inp. 1080 */ 1081 rstreason = syncache_expand(&inc, &to, th, &so, m, port); 1082 if (rstreason < 0) { 1083 /* 1084 * A failing TCP MD5 signature comparison 1085 * must result in the segment being dropped 1086 * and must not produce any response back 1087 * to the sender. 1088 */ 1089 goto dropunlock; 1090 } else if (rstreason == 0) { 1091 /* 1092 * No syncache entry, or ACK was not for our 1093 * SYN/ACK. Do our protection against double 1094 * ACK. If peer sent us 2 ACKs, then for the 1095 * first one syncache_expand() successfully 1096 * converted syncache entry into a socket, 1097 * while we were waiting on the inpcb lock. We 1098 * don't want to sent RST for the second ACK, 1099 * so we perform second lookup without wildcard 1100 * match, hoping to find the new socket. If 1101 * the ACK is stray indeed, rstreason would 1102 * hint the above code that the lookup was a 1103 * second attempt. 1104 * 1105 * NB: syncache did its own logging 1106 * of the failure cause. 1107 */ 1108 INP_WUNLOCK(inp); 1109 rstreason = BANDLIM_RST_OPENPORT; 1110 lookupflag &= ~INPLOOKUP_WILDCARD; 1111 goto findpcb; 1112 } 1113 tfo_socket_result: 1114 if (so == NULL) { 1115 /* 1116 * We completed the 3-way handshake 1117 * but could not allocate a socket 1118 * either due to memory shortage, 1119 * listen queue length limits or 1120 * global socket limits. Send RST 1121 * or wait and have the remote end 1122 * retransmit the ACK for another 1123 * try. 1124 */ 1125 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1126 log(LOG_DEBUG, "%s; %s: Listen socket: " 1127 "Socket allocation failed due to " 1128 "limits or memory shortage, %s\n", 1129 s, __func__, 1130 V_tcp_sc_rst_sock_fail ? 1131 "sending RST" : "try again"); 1132 if (V_tcp_sc_rst_sock_fail) { 1133 rstreason = BANDLIM_UNLIMITED; 1134 goto dropwithreset; 1135 } else 1136 goto dropunlock; 1137 } 1138 /* 1139 * Socket is created in state SYN_RECEIVED. 1140 * Unlock the listen socket, lock the newly 1141 * created socket and update the tp variable. 1142 * If we came here via jump to tfo_socket_result, 1143 * then listening socket is read-locked. 1144 */ 1145 INP_UNLOCK(inp); /* listen socket */ 1146 inp = sotoinpcb(so); 1147 /* 1148 * New connection inpcb is already locked by 1149 * syncache_expand(). 1150 */ 1151 INP_WLOCK_ASSERT(inp); 1152 tp = intotcpcb(inp); 1153 KASSERT(tp->t_state == TCPS_SYN_RECEIVED, 1154 ("%s: ", __func__)); 1155 /* 1156 * Process the segment and the data it 1157 * contains. tcp_do_segment() consumes 1158 * the mbuf chain and unlocks the inpcb. 1159 */ 1160 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1161 tp->t_fb->tfb_tcp_do_segment(tp, m, th, drop_hdrlen, 1162 tlen, iptos); 1163 return (IPPROTO_DONE); 1164 } 1165 /* 1166 * Segment flag validation for new connection attempts: 1167 * 1168 * Our (SYN|ACK) response was rejected. 1169 * Check with syncache and remove entry to prevent 1170 * retransmits. 1171 * 1172 * NB: syncache_chkrst does its own logging of failure 1173 * causes. 1174 */ 1175 if (thflags & TH_RST) { 1176 syncache_chkrst(&inc, th, m, port); 1177 goto dropunlock; 1178 } 1179 /* 1180 * We can't do anything without SYN. 1181 */ 1182 if ((thflags & TH_SYN) == 0) { 1183 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1184 log(LOG_DEBUG, "%s; %s: Listen socket: " 1185 "SYN is missing, segment ignored\n", 1186 s, __func__); 1187 TCPSTAT_INC(tcps_badsyn); 1188 goto dropunlock; 1189 } 1190 /* 1191 * (SYN|ACK) is bogus on a listen socket. 1192 */ 1193 if (thflags & TH_ACK) { 1194 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1195 log(LOG_DEBUG, "%s; %s: Listen socket: " 1196 "SYN|ACK invalid, segment rejected\n", 1197 s, __func__); 1198 syncache_badack(&inc, port); /* XXX: Not needed! */ 1199 TCPSTAT_INC(tcps_badsyn); 1200 rstreason = BANDLIM_RST_OPENPORT; 1201 goto dropwithreset; 1202 } 1203 /* 1204 * If the drop_synfin option is enabled, drop all 1205 * segments with both the SYN and FIN bits set. 1206 * This prevents e.g. nmap from identifying the 1207 * TCP/IP stack. 1208 * XXX: Poor reasoning. nmap has other methods 1209 * and is constantly refining its stack detection 1210 * strategies. 1211 * XXX: This is a violation of the TCP specification 1212 * and was used by RFC1644. 1213 */ 1214 if ((thflags & TH_FIN) && V_drop_synfin) { 1215 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1216 log(LOG_DEBUG, "%s; %s: Listen socket: " 1217 "SYN|FIN segment ignored (based on " 1218 "sysctl setting)\n", s, __func__); 1219 TCPSTAT_INC(tcps_badsyn); 1220 goto dropunlock; 1221 } 1222 /* 1223 * Segment's flags are (SYN) or (SYN|FIN). 1224 * 1225 * TH_PUSH, TH_URG, TH_ECE, TH_CWR are ignored 1226 * as they do not affect the state of the TCP FSM. 1227 * The data pointed to by TH_URG and th_urp is ignored. 1228 */ 1229 KASSERT((thflags & (TH_RST|TH_ACK)) == 0, 1230 ("%s: Listen socket: TH_RST or TH_ACK set", __func__)); 1231 KASSERT(thflags & (TH_SYN), 1232 ("%s: Listen socket: TH_SYN not set", __func__)); 1233 INP_RLOCK_ASSERT(inp); 1234 #ifdef INET6 1235 /* 1236 * If deprecated address is forbidden, 1237 * we do not accept SYN to deprecated interface 1238 * address to prevent any new inbound connection from 1239 * getting established. 1240 * When we do not accept SYN, we send a TCP RST, 1241 * with deprecated source address (instead of dropping 1242 * it). We compromise it as it is much better for peer 1243 * to send a RST, and RST will be the final packet 1244 * for the exchange. 1245 * 1246 * If we do not forbid deprecated addresses, we accept 1247 * the SYN packet. RFC2462 does not suggest dropping 1248 * SYN in this case. 1249 * If we decipher RFC2462 5.5.4, it says like this: 1250 * 1. use of deprecated addr with existing 1251 * communication is okay - "SHOULD continue to be 1252 * used" 1253 * 2. use of it with new communication: 1254 * (2a) "SHOULD NOT be used if alternate address 1255 * with sufficient scope is available" 1256 * (2b) nothing mentioned otherwise. 1257 * Here we fall into (2b) case as we have no choice in 1258 * our source address selection - we must obey the peer. 1259 * 1260 * The wording in RFC2462 is confusing, and there are 1261 * multiple description text for deprecated address 1262 * handling - worse, they are not exactly the same. 1263 * I believe 5.5.4 is the best one, so we follow 5.5.4. 1264 */ 1265 if (isipv6 && !V_ip6_use_deprecated) { 1266 struct in6_ifaddr *ia6; 1267 1268 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false); 1269 if (ia6 != NULL && 1270 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) { 1271 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1272 log(LOG_DEBUG, "%s; %s: Listen socket: " 1273 "Connection attempt to deprecated " 1274 "IPv6 address rejected\n", 1275 s, __func__); 1276 rstreason = BANDLIM_RST_OPENPORT; 1277 goto dropwithreset; 1278 } 1279 } 1280 #endif /* INET6 */ 1281 /* 1282 * Basic sanity checks on incoming SYN requests: 1283 * Don't respond if the destination is a link layer 1284 * broadcast according to RFC1122 4.2.3.10, p. 104. 1285 * If it is from this socket it must be forged. 1286 * Don't respond if the source or destination is a 1287 * global or subnet broad- or multicast address. 1288 * Note that it is quite possible to receive unicast 1289 * link-layer packets with a broadcast IP address. Use 1290 * in_broadcast() to find them. 1291 */ 1292 if (m->m_flags & (M_BCAST|M_MCAST)) { 1293 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1294 log(LOG_DEBUG, "%s; %s: Listen socket: " 1295 "Connection attempt from broad- or multicast " 1296 "link layer address ignored\n", s, __func__); 1297 goto dropunlock; 1298 } 1299 #ifdef INET6 1300 if (isipv6) { 1301 if (th->th_dport == th->th_sport && 1302 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &ip6->ip6_src)) { 1303 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1304 log(LOG_DEBUG, "%s; %s: Listen socket: " 1305 "Connection attempt to/from self " 1306 "ignored\n", s, __func__); 1307 goto dropunlock; 1308 } 1309 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 1310 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) { 1311 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1312 log(LOG_DEBUG, "%s; %s: Listen socket: " 1313 "Connection attempt from/to multicast " 1314 "address ignored\n", s, __func__); 1315 goto dropunlock; 1316 } 1317 } 1318 #endif 1319 #if defined(INET) && defined(INET6) 1320 else 1321 #endif 1322 #ifdef INET 1323 { 1324 if (th->th_dport == th->th_sport && 1325 ip->ip_dst.s_addr == ip->ip_src.s_addr) { 1326 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1327 log(LOG_DEBUG, "%s; %s: Listen socket: " 1328 "Connection attempt from/to self " 1329 "ignored\n", s, __func__); 1330 goto dropunlock; 1331 } 1332 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 1333 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 1334 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || 1335 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) { 1336 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1337 log(LOG_DEBUG, "%s; %s: Listen socket: " 1338 "Connection attempt from/to broad- " 1339 "or multicast address ignored\n", 1340 s, __func__); 1341 goto dropunlock; 1342 } 1343 } 1344 #endif 1345 /* 1346 * SYN appears to be valid. Create compressed TCP state 1347 * for syncache. 1348 */ 1349 TCP_PROBE3(debug__input, tp, th, m); 1350 tcp_dooptions(&to, optp, optlen, TO_SYN); 1351 if ((so = syncache_add(&inc, &to, th, inp, so, m, NULL, NULL, 1352 iptos, port)) != NULL) 1353 goto tfo_socket_result; 1354 1355 /* 1356 * Entry added to syncache and mbuf consumed. 1357 * Only the listen socket is unlocked by syncache_add(). 1358 */ 1359 return (IPPROTO_DONE); 1360 } else if (tp->t_state == TCPS_LISTEN) { 1361 /* 1362 * When a listen socket is torn down the SO_ACCEPTCONN 1363 * flag is removed first while connections are drained 1364 * from the accept queue in a unlock/lock cycle of the 1365 * ACCEPT_LOCK, opening a race condition allowing a SYN 1366 * attempt go through unhandled. 1367 */ 1368 goto dropunlock; 1369 } 1370 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 1371 if (tp->t_flags & TF_SIGNATURE) { 1372 tcp_dooptions(&to, optp, optlen, thflags); 1373 if ((to.to_flags & TOF_SIGNATURE) == 0) { 1374 TCPSTAT_INC(tcps_sig_err_nosigopt); 1375 goto dropunlock; 1376 } 1377 if (!TCPMD5_ENABLED() || 1378 TCPMD5_INPUT(m, th, to.to_signature) != 0) 1379 goto dropunlock; 1380 } 1381 #endif 1382 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1383 1384 /* 1385 * Segment belongs to a connection in SYN_SENT, ESTABLISHED or later 1386 * state. tcp_do_segment() always consumes the mbuf chain, unlocks 1387 * the inpcb, and unlocks pcbinfo. 1388 * 1389 * XXXGL: in case of a pure SYN arriving on existing connection 1390 * TCP stacks won't need to modify the PCB, they would either drop 1391 * the segment silently, or send a challenge ACK. However, we try 1392 * to upgrade the lock, because calling convention for stacks is 1393 * write-lock on PCB. If upgrade fails, drop the SYN. 1394 */ 1395 if ((lookupflag & INPLOOKUP_RLOCKPCB) && INP_TRY_UPGRADE(inp) == 0) 1396 goto dropunlock; 1397 1398 tp->t_fb->tfb_tcp_do_segment(tp, m, th, drop_hdrlen, tlen, iptos); 1399 return (IPPROTO_DONE); 1400 1401 dropwithreset: 1402 /* 1403 * When blackholing do not respond with a RST but 1404 * completely ignore the segment and drop it. 1405 */ 1406 if (((rstreason == BANDLIM_RST_OPENPORT && V_blackhole == 3) || 1407 (rstreason == BANDLIM_RST_CLOSEDPORT && 1408 ((V_blackhole == 1 && (thflags & TH_SYN)) || V_blackhole > 1))) && 1409 (V_blackhole_local || ( 1410 #ifdef INET6 1411 isipv6 ? !in6_localaddr(&ip6->ip6_src) : 1412 #endif 1413 #ifdef INET 1414 !in_localip(ip->ip_src) 1415 #else 1416 true 1417 #endif 1418 ))) 1419 goto dropunlock; 1420 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1421 tcp_dropwithreset(m, th, tp, tlen, rstreason); 1422 m = NULL; /* mbuf chain got consumed. */ 1423 1424 dropunlock: 1425 if (m != NULL) 1426 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1427 1428 if (inp != NULL) 1429 INP_UNLOCK(inp); 1430 1431 drop: 1432 if (s != NULL) 1433 free(s, M_TCPLOG); 1434 if (m != NULL) 1435 m_freem(m); 1436 return (IPPROTO_DONE); 1437 } 1438 1439 /* 1440 * Automatic sizing of receive socket buffer. Often the send 1441 * buffer size is not optimally adjusted to the actual network 1442 * conditions at hand (delay bandwidth product). Setting the 1443 * buffer size too small limits throughput on links with high 1444 * bandwidth and high delay (eg. trans-continental/oceanic links). 1445 * 1446 * On the receive side the socket buffer memory is only rarely 1447 * used to any significant extent. This allows us to be much 1448 * more aggressive in scaling the receive socket buffer. For 1449 * the case that the buffer space is actually used to a large 1450 * extent and we run out of kernel memory we can simply drop 1451 * the new segments; TCP on the sender will just retransmit it 1452 * later. Setting the buffer size too big may only consume too 1453 * much kernel memory if the application doesn't read() from 1454 * the socket or packet loss or reordering makes use of the 1455 * reassembly queue. 1456 * 1457 * The criteria to step up the receive buffer one notch are: 1458 * 1. Application has not set receive buffer size with 1459 * SO_RCVBUF. Setting SO_RCVBUF clears SB_AUTOSIZE. 1460 * 2. the number of bytes received during 1/2 of an sRTT 1461 * is at least 3/8 of the current socket buffer size. 1462 * 3. receive buffer size has not hit maximal automatic size; 1463 * 1464 * If all of the criteria are met we increaset the socket buffer 1465 * by a 1/2 (bounded by the max). This allows us to keep ahead 1466 * of slow-start but also makes it so our peer never gets limited 1467 * by our rwnd which we then open up causing a burst. 1468 * 1469 * This algorithm does two steps per RTT at most and only if 1470 * we receive a bulk stream w/o packet losses or reorderings. 1471 * Shrinking the buffer during idle times is not necessary as 1472 * it doesn't consume any memory when idle. 1473 * 1474 * TODO: Only step up if the application is actually serving 1475 * the buffer to better manage the socket buffer resources. 1476 */ 1477 int 1478 tcp_autorcvbuf(struct mbuf *m, struct tcphdr *th, struct socket *so, 1479 struct tcpcb *tp, int tlen) 1480 { 1481 int newsize = 0; 1482 1483 if (V_tcp_do_autorcvbuf && (so->so_rcv.sb_flags & SB_AUTOSIZE) && 1484 tp->t_srtt != 0 && tp->rfbuf_ts != 0 && 1485 TCP_TS_TO_TICKS(tcp_ts_getticks() - tp->rfbuf_ts) > 1486 ((tp->t_srtt >> TCP_RTT_SHIFT)/2)) { 1487 if (tp->rfbuf_cnt > ((so->so_rcv.sb_hiwat / 2)/ 4 * 3) && 1488 so->so_rcv.sb_hiwat < V_tcp_autorcvbuf_max) { 1489 newsize = min((so->so_rcv.sb_hiwat + (so->so_rcv.sb_hiwat/2)), V_tcp_autorcvbuf_max); 1490 } 1491 TCP_PROBE6(receive__autoresize, NULL, tp, m, tp, th, newsize); 1492 1493 /* Start over with next RTT. */ 1494 tp->rfbuf_ts = 0; 1495 tp->rfbuf_cnt = 0; 1496 } else { 1497 tp->rfbuf_cnt += tlen; /* add up */ 1498 } 1499 return (newsize); 1500 } 1501 1502 int 1503 tcp_input(struct mbuf **mp, int *offp, int proto) 1504 { 1505 return(tcp_input_with_port(mp, offp, proto, 0)); 1506 } 1507 1508 static void 1509 tcp_handle_wakeup(struct tcpcb *tp) 1510 { 1511 1512 INP_WLOCK_ASSERT(tptoinpcb(tp)); 1513 1514 if (tp->t_flags & TF_WAKESOR) { 1515 struct socket *so = tptosocket(tp); 1516 1517 tp->t_flags &= ~TF_WAKESOR; 1518 SOCKBUF_LOCK_ASSERT(&so->so_rcv); 1519 sorwakeup_locked(so); 1520 } 1521 } 1522 1523 void 1524 tcp_do_segment(struct tcpcb *tp, struct mbuf *m, struct tcphdr *th, 1525 int drop_hdrlen, int tlen, uint8_t iptos) 1526 { 1527 uint16_t thflags; 1528 int acked, ourfinisacked, needoutput = 0; 1529 sackstatus_t sack_changed; 1530 int rstreason, todrop, win, incforsyn = 0; 1531 uint32_t tiwin; 1532 uint16_t nsegs; 1533 char *s; 1534 struct inpcb *inp = tptoinpcb(tp); 1535 struct socket *so = tptosocket(tp); 1536 struct in_conninfo *inc = &inp->inp_inc; 1537 struct mbuf *mfree; 1538 struct tcpopt to; 1539 int tfo_syn; 1540 u_int maxseg = 0; 1541 1542 thflags = tcp_get_flags(th); 1543 tp->sackhint.last_sack_ack = 0; 1544 sack_changed = SACK_NOCHANGE; 1545 nsegs = max(1, m->m_pkthdr.lro_nsegs); 1546 1547 NET_EPOCH_ASSERT(); 1548 INP_WLOCK_ASSERT(inp); 1549 KASSERT(tp->t_state > TCPS_LISTEN, ("%s: TCPS_LISTEN", 1550 __func__)); 1551 KASSERT(tp->t_state != TCPS_TIME_WAIT, ("%s: TCPS_TIME_WAIT", 1552 __func__)); 1553 1554 #ifdef TCPPCAP 1555 /* Save segment, if requested. */ 1556 tcp_pcap_add(th, m, &(tp->t_inpkts)); 1557 #endif 1558 TCP_LOG_EVENT(tp, th, &so->so_rcv, &so->so_snd, TCP_LOG_IN, 0, 1559 tlen, NULL, true); 1560 1561 if ((thflags & TH_SYN) && (thflags & TH_FIN) && V_drop_synfin) { 1562 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1563 log(LOG_DEBUG, "%s; %s: " 1564 "SYN|FIN segment ignored (based on " 1565 "sysctl setting)\n", s, __func__); 1566 free(s, M_TCPLOG); 1567 } 1568 goto drop; 1569 } 1570 1571 /* 1572 * If a segment with the ACK-bit set arrives in the SYN-SENT state 1573 * check SEQ.ACK first. 1574 */ 1575 if ((tp->t_state == TCPS_SYN_SENT) && (thflags & TH_ACK) && 1576 (SEQ_LEQ(th->th_ack, tp->iss) || SEQ_GT(th->th_ack, tp->snd_max))) { 1577 rstreason = BANDLIM_UNLIMITED; 1578 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 1579 goto dropwithreset; 1580 } 1581 1582 /* 1583 * Segment received on connection. 1584 * Reset idle time and keep-alive timer. 1585 * XXX: This should be done after segment 1586 * validation to ignore broken/spoofed segs. 1587 */ 1588 if (tp->t_idle_reduce && 1589 (tp->snd_max == tp->snd_una) && 1590 ((ticks - tp->t_rcvtime) >= tp->t_rxtcur)) 1591 cc_after_idle(tp); 1592 tp->t_rcvtime = ticks; 1593 1594 if (thflags & TH_FIN) 1595 tcp_log_end_status(tp, TCP_EI_STATUS_CLIENT_FIN); 1596 /* 1597 * Scale up the window into a 32-bit value. 1598 * For the SYN_SENT state the scale is zero. 1599 */ 1600 tiwin = th->th_win << tp->snd_scale; 1601 #ifdef STATS 1602 stats_voi_update_abs_ulong(tp->t_stats, VOI_TCP_FRWIN, tiwin); 1603 #endif 1604 1605 /* 1606 * TCP ECN processing. 1607 */ 1608 if (tcp_ecn_input_segment(tp, thflags, tlen, 1609 tcp_packets_this_ack(tp, th->th_ack), 1610 iptos)) 1611 cc_cong_signal(tp, th, CC_ECN); 1612 1613 /* 1614 * Parse options on any incoming segment. 1615 */ 1616 tcp_dooptions(&to, (u_char *)(th + 1), 1617 (th->th_off << 2) - sizeof(struct tcphdr), 1618 (thflags & TH_SYN) ? TO_SYN : 0); 1619 if (tp->t_flags2 & TF2_PROC_SACK_PROHIBIT) { 1620 /* 1621 * We don't look at sack's from the 1622 * peer because the MSS is too small which 1623 * can subject us to an attack. 1624 */ 1625 to.to_flags &= ~TOF_SACK; 1626 } 1627 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 1628 if ((tp->t_flags & TF_SIGNATURE) != 0 && 1629 (to.to_flags & TOF_SIGNATURE) == 0) { 1630 TCPSTAT_INC(tcps_sig_err_sigopt); 1631 /* XXX: should drop? */ 1632 } 1633 #endif 1634 /* 1635 * If echoed timestamp is later than the current time, 1636 * fall back to non RFC1323 RTT calculation. Normalize 1637 * timestamp if syncookies were used when this connection 1638 * was established. 1639 */ 1640 if ((to.to_flags & TOF_TS) && (to.to_tsecr != 0)) { 1641 to.to_tsecr -= tp->ts_offset; 1642 if (TSTMP_GT(to.to_tsecr, tcp_ts_getticks())) { 1643 to.to_tsecr = 0; 1644 } else if (tp->t_rxtshift == 1 && 1645 tp->t_flags & TF_PREVVALID && 1646 tp->t_badrxtwin != 0 && 1647 TSTMP_LT(to.to_tsecr, tp->t_badrxtwin)) { 1648 cc_cong_signal(tp, th, CC_RTO_ERR); 1649 } 1650 } 1651 /* 1652 * Process options only when we get SYN/ACK back. The SYN case 1653 * for incoming connections is handled in tcp_syncache. 1654 * According to RFC1323 the window field in a SYN (i.e., a <SYN> 1655 * or <SYN,ACK>) segment itself is never scaled. 1656 * XXX this is traditional behavior, may need to be cleaned up. 1657 */ 1658 if (tp->t_state == TCPS_SYN_SENT && (thflags & TH_SYN)) { 1659 /* Handle parallel SYN for ECN */ 1660 tcp_ecn_input_parallel_syn(tp, thflags, iptos); 1661 if ((to.to_flags & TOF_SCALE) && 1662 (tp->t_flags & TF_REQ_SCALE) && 1663 !(tp->t_flags & TF_NOOPT)) { 1664 tp->t_flags |= TF_RCVD_SCALE; 1665 tp->snd_scale = to.to_wscale; 1666 } else { 1667 tp->t_flags &= ~TF_REQ_SCALE; 1668 } 1669 /* 1670 * Initial send window. It will be updated with 1671 * the next incoming segment to the scaled value. 1672 */ 1673 tp->snd_wnd = th->th_win; 1674 if ((to.to_flags & TOF_TS) && 1675 (tp->t_flags & TF_REQ_TSTMP) && 1676 !(tp->t_flags & TF_NOOPT)) { 1677 tp->t_flags |= TF_RCVD_TSTMP; 1678 tp->ts_recent = to.to_tsval; 1679 tp->ts_recent_age = tcp_ts_getticks(); 1680 } else { 1681 tp->t_flags &= ~TF_REQ_TSTMP; 1682 } 1683 if (to.to_flags & TOF_MSS) { 1684 tcp_mss(tp, to.to_mss); 1685 } 1686 if ((tp->t_flags & TF_SACK_PERMIT) && 1687 (!(to.to_flags & TOF_SACKPERM) || 1688 (tp->t_flags & TF_NOOPT))) { 1689 tp->t_flags &= ~TF_SACK_PERMIT; 1690 } 1691 if (tp->t_flags & TF_FASTOPEN) { 1692 if ((to.to_flags & TOF_FASTOPEN) && 1693 !(tp->t_flags & TF_NOOPT)) { 1694 uint16_t mss; 1695 1696 if (to.to_flags & TOF_MSS) { 1697 mss = to.to_mss; 1698 } else { 1699 if ((inp->inp_vflag & INP_IPV6) != 0) { 1700 mss = TCP6_MSS; 1701 } else { 1702 mss = TCP_MSS; 1703 } 1704 } 1705 tcp_fastopen_update_cache(tp, mss, 1706 to.to_tfo_len, to.to_tfo_cookie); 1707 } else { 1708 tcp_fastopen_disable_path(tp); 1709 } 1710 } 1711 } 1712 1713 /* 1714 * If timestamps were negotiated during SYN/ACK and a 1715 * segment without a timestamp is received, silently drop 1716 * the segment, unless it is a RST segment or missing timestamps are 1717 * tolerated. 1718 * See section 3.2 of RFC 7323. 1719 */ 1720 if ((tp->t_flags & TF_RCVD_TSTMP) && !(to.to_flags & TOF_TS)) { 1721 if (((thflags & TH_RST) != 0) || V_tcp_tolerate_missing_ts) { 1722 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1723 log(LOG_DEBUG, "%s; %s: Timestamp missing, " 1724 "segment processed normally\n", 1725 s, __func__); 1726 free(s, M_TCPLOG); 1727 } 1728 } else { 1729 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1730 log(LOG_DEBUG, "%s; %s: Timestamp missing, " 1731 "segment silently dropped\n", s, __func__); 1732 free(s, M_TCPLOG); 1733 } 1734 goto drop; 1735 } 1736 } 1737 /* 1738 * If timestamps were not negotiated during SYN/ACK and a 1739 * segment with a timestamp is received, ignore the 1740 * timestamp and process the packet normally. 1741 * See section 3.2 of RFC 7323. 1742 */ 1743 if (!(tp->t_flags & TF_RCVD_TSTMP) && (to.to_flags & TOF_TS)) { 1744 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1745 log(LOG_DEBUG, "%s; %s: Timestamp not expected, " 1746 "segment processed normally\n", s, __func__); 1747 free(s, M_TCPLOG); 1748 } 1749 } 1750 1751 /* 1752 * Header prediction: check for the two common cases 1753 * of a uni-directional data xfer. If the packet has 1754 * no control flags, is in-sequence, the window didn't 1755 * change and we're not retransmitting, it's a 1756 * candidate. If the length is zero and the ack moved 1757 * forward, we're the sender side of the xfer. Just 1758 * free the data acked & wake any higher level process 1759 * that was blocked waiting for space. If the length 1760 * is non-zero and the ack didn't move, we're the 1761 * receiver side. If we're getting packets in-order 1762 * (the reassembly queue is empty), add the data to 1763 * the socket buffer and note that we need a delayed ack. 1764 * Make sure that the hidden state-flags are also off. 1765 * Since we check for TCPS_ESTABLISHED first, it can only 1766 * be TH_NEEDSYN. 1767 */ 1768 if (tp->t_state == TCPS_ESTABLISHED && 1769 th->th_seq == tp->rcv_nxt && 1770 (thflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK && 1771 tp->snd_nxt == tp->snd_max && 1772 tiwin && tiwin == tp->snd_wnd && 1773 ((tp->t_flags & (TF_NEEDSYN|TF_NEEDFIN)) == 0) && 1774 SEGQ_EMPTY(tp) && 1775 ((to.to_flags & TOF_TS) == 0 || 1776 TSTMP_GEQ(to.to_tsval, tp->ts_recent)) ) { 1777 /* 1778 * If last ACK falls within this segment's sequence numbers, 1779 * record the timestamp. 1780 * NOTE that the test is modified according to the latest 1781 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 1782 */ 1783 if ((to.to_flags & TOF_TS) != 0 && 1784 SEQ_LEQ(th->th_seq, tp->last_ack_sent)) { 1785 tp->ts_recent_age = tcp_ts_getticks(); 1786 tp->ts_recent = to.to_tsval; 1787 } 1788 1789 if (tlen == 0) { 1790 if (SEQ_GT(th->th_ack, tp->snd_una) && 1791 SEQ_LEQ(th->th_ack, tp->snd_max) && 1792 !IN_RECOVERY(tp->t_flags) && 1793 (to.to_flags & TOF_SACK) == 0 && 1794 TAILQ_EMPTY(&tp->snd_holes)) { 1795 /* 1796 * This is a pure ack for outstanding data. 1797 */ 1798 TCPSTAT_INC(tcps_predack); 1799 1800 /* 1801 * "bad retransmit" recovery without timestamps. 1802 */ 1803 if ((to.to_flags & TOF_TS) == 0 && 1804 tp->t_rxtshift == 1 && 1805 tp->t_flags & TF_PREVVALID && 1806 tp->t_badrxtwin != 0 && 1807 TSTMP_LT(ticks, tp->t_badrxtwin)) { 1808 cc_cong_signal(tp, th, CC_RTO_ERR); 1809 } 1810 1811 /* 1812 * Recalculate the transmit timer / rtt. 1813 * 1814 * Some boxes send broken timestamp replies 1815 * during the SYN+ACK phase, ignore 1816 * timestamps of 0 or we could calculate a 1817 * huge RTT and blow up the retransmit timer. 1818 */ 1819 if ((to.to_flags & TOF_TS) != 0 && 1820 to.to_tsecr) { 1821 uint32_t t; 1822 1823 t = tcp_ts_getticks() - to.to_tsecr; 1824 if (!tp->t_rttlow || tp->t_rttlow > t) 1825 tp->t_rttlow = t; 1826 tcp_xmit_timer(tp, 1827 TCP_TS_TO_TICKS(t) + 1); 1828 } else if (tp->t_rtttime && 1829 SEQ_GT(th->th_ack, tp->t_rtseq)) { 1830 if (!tp->t_rttlow || 1831 tp->t_rttlow > ticks - tp->t_rtttime) 1832 tp->t_rttlow = ticks - tp->t_rtttime; 1833 tcp_xmit_timer(tp, 1834 ticks - tp->t_rtttime); 1835 } 1836 acked = BYTES_THIS_ACK(tp, th); 1837 1838 #ifdef TCP_HHOOK 1839 /* Run HHOOK_TCP_ESTABLISHED_IN helper hooks. */ 1840 hhook_run_tcp_est_in(tp, th, &to); 1841 #endif 1842 1843 TCPSTAT_ADD(tcps_rcvackpack, nsegs); 1844 TCPSTAT_ADD(tcps_rcvackbyte, acked); 1845 sbdrop(&so->so_snd, acked); 1846 if (SEQ_GT(tp->snd_una, tp->snd_recover) && 1847 SEQ_LEQ(th->th_ack, tp->snd_recover)) 1848 tp->snd_recover = th->th_ack - 1; 1849 1850 /* 1851 * Let the congestion control algorithm update 1852 * congestion control related information. This 1853 * typically means increasing the congestion 1854 * window. 1855 */ 1856 cc_ack_received(tp, th, nsegs, CC_ACK); 1857 1858 tp->snd_una = th->th_ack; 1859 /* 1860 * Pull snd_wl2 up to prevent seq wrap relative 1861 * to th_ack. 1862 */ 1863 tp->snd_wl2 = th->th_ack; 1864 tp->t_dupacks = 0; 1865 m_freem(m); 1866 1867 /* 1868 * If all outstanding data are acked, stop 1869 * retransmit timer, otherwise restart timer 1870 * using current (possibly backed-off) value. 1871 * If process is waiting for space, 1872 * wakeup/selwakeup/signal. If data 1873 * are ready to send, let tcp_output 1874 * decide between more output or persist. 1875 */ 1876 TCP_PROBE3(debug__input, tp, th, m); 1877 /* 1878 * Clear t_acktime if remote side has ACKd 1879 * all data in the socket buffer. 1880 * Otherwise, update t_acktime if we received 1881 * a sufficiently large ACK. 1882 */ 1883 if (sbavail(&so->so_snd) == 0) 1884 tp->t_acktime = 0; 1885 else if (acked > 1) 1886 tp->t_acktime = ticks; 1887 if (tp->snd_una == tp->snd_max) 1888 tcp_timer_activate(tp, TT_REXMT, 0); 1889 else if (!tcp_timer_active(tp, TT_PERSIST)) 1890 tcp_timer_activate(tp, TT_REXMT, 1891 TP_RXTCUR(tp)); 1892 sowwakeup(so); 1893 /* 1894 * Only call tcp_output when there 1895 * is new data available to be sent 1896 * or we need to send an ACK. 1897 */ 1898 if ((tp->t_flags & TF_ACKNOW) || 1899 (sbavail(&so->so_snd) >= 1900 SEQ_SUB(tp->snd_max, tp->snd_una))) { 1901 (void) tcp_output(tp); 1902 } 1903 goto check_delack; 1904 } 1905 } else if (th->th_ack == tp->snd_una && 1906 tlen <= sbspace(&so->so_rcv)) { 1907 int newsize = 0; /* automatic sockbuf scaling */ 1908 1909 /* 1910 * This is a pure, in-sequence data packet with 1911 * nothing on the reassembly queue and we have enough 1912 * buffer space to take it. 1913 */ 1914 /* Clean receiver SACK report if present */ 1915 if ((tp->t_flags & TF_SACK_PERMIT) && tp->rcv_numsacks) 1916 tcp_clean_sackreport(tp); 1917 TCPSTAT_INC(tcps_preddat); 1918 tp->rcv_nxt += tlen; 1919 if (tlen && 1920 ((tp->t_flags2 & TF2_FBYTES_COMPLETE) == 0) && 1921 (tp->t_fbyte_in == 0)) { 1922 tp->t_fbyte_in = ticks; 1923 if (tp->t_fbyte_in == 0) 1924 tp->t_fbyte_in = 1; 1925 if (tp->t_fbyte_out && tp->t_fbyte_in) 1926 tp->t_flags2 |= TF2_FBYTES_COMPLETE; 1927 } 1928 /* 1929 * Pull snd_wl1 up to prevent seq wrap relative to 1930 * th_seq. 1931 */ 1932 tp->snd_wl1 = th->th_seq; 1933 /* 1934 * Pull rcv_up up to prevent seq wrap relative to 1935 * rcv_nxt. 1936 */ 1937 tp->rcv_up = tp->rcv_nxt; 1938 TCPSTAT_ADD(tcps_rcvpack, nsegs); 1939 TCPSTAT_ADD(tcps_rcvbyte, tlen); 1940 TCP_PROBE3(debug__input, tp, th, m); 1941 1942 newsize = tcp_autorcvbuf(m, th, so, tp, tlen); 1943 1944 /* Add data to socket buffer. */ 1945 SOCKBUF_LOCK(&so->so_rcv); 1946 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 1947 m_freem(m); 1948 } else { 1949 /* 1950 * Set new socket buffer size. 1951 * Give up when limit is reached. 1952 */ 1953 if (newsize) 1954 if (!sbreserve_locked(so, SO_RCV, 1955 newsize, NULL)) 1956 so->so_rcv.sb_flags &= ~SB_AUTOSIZE; 1957 m_adj(m, drop_hdrlen); /* delayed header drop */ 1958 sbappendstream_locked(&so->so_rcv, m, 0); 1959 } 1960 /* NB: sorwakeup_locked() does an implicit unlock. */ 1961 sorwakeup_locked(so); 1962 if (DELAY_ACK(tp, tlen)) { 1963 tp->t_flags |= TF_DELACK; 1964 } else { 1965 tp->t_flags |= TF_ACKNOW; 1966 (void) tcp_output(tp); 1967 } 1968 goto check_delack; 1969 } 1970 } 1971 1972 /* 1973 * Calculate amount of space in receive window, 1974 * and then do TCP input processing. 1975 * Receive window is amount of space in rcv queue, 1976 * but not less than advertised window. 1977 */ 1978 win = sbspace(&so->so_rcv); 1979 if (win < 0) 1980 win = 0; 1981 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 1982 1983 switch (tp->t_state) { 1984 /* 1985 * If the state is SYN_RECEIVED: 1986 * if seg contains an ACK, but not for our SYN/ACK, send a RST. 1987 */ 1988 case TCPS_SYN_RECEIVED: 1989 if (thflags & TH_RST) { 1990 /* Handle RST segments later. */ 1991 break; 1992 } 1993 if ((thflags & TH_ACK) && 1994 (SEQ_LEQ(th->th_ack, tp->snd_una) || 1995 SEQ_GT(th->th_ack, tp->snd_max))) { 1996 rstreason = BANDLIM_RST_OPENPORT; 1997 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 1998 goto dropwithreset; 1999 } 2000 if (tp->t_flags & TF_FASTOPEN) { 2001 /* 2002 * When a TFO connection is in SYN_RECEIVED, the 2003 * only valid packets are the initial SYN, a 2004 * retransmit/copy of the initial SYN (possibly with 2005 * a subset of the original data), a valid ACK, a 2006 * FIN, or a RST. 2007 */ 2008 if ((thflags & (TH_SYN|TH_ACK)) == (TH_SYN|TH_ACK)) { 2009 rstreason = BANDLIM_RST_OPENPORT; 2010 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 2011 goto dropwithreset; 2012 } else if (thflags & TH_SYN) { 2013 /* non-initial SYN is ignored */ 2014 if ((tcp_timer_active(tp, TT_DELACK) || 2015 tcp_timer_active(tp, TT_REXMT))) 2016 goto drop; 2017 } else if (!(thflags & (TH_ACK|TH_FIN|TH_RST))) { 2018 goto drop; 2019 } 2020 } 2021 break; 2022 2023 /* 2024 * If the state is SYN_SENT: 2025 * if seg contains a RST with valid ACK (SEQ.ACK has already 2026 * been verified), then drop the connection. 2027 * if seg contains a RST without an ACK, drop the seg. 2028 * if seg does not contain SYN, then drop the seg. 2029 * Otherwise this is an acceptable SYN segment 2030 * initialize tp->rcv_nxt and tp->irs 2031 * if seg contains ack then advance tp->snd_una 2032 * if seg contains an ECE and ECN support is enabled, the stream 2033 * is ECN capable. 2034 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 2035 * arrange for segment to be acked (eventually) 2036 * continue processing rest of data/controls, beginning with URG 2037 */ 2038 case TCPS_SYN_SENT: 2039 if ((thflags & (TH_ACK|TH_RST)) == (TH_ACK|TH_RST)) { 2040 TCP_PROBE5(connect__refused, NULL, tp, 2041 m, tp, th); 2042 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 2043 tp = tcp_drop(tp, ECONNREFUSED); 2044 } 2045 if (thflags & TH_RST) 2046 goto drop; 2047 if (!(thflags & TH_SYN)) 2048 goto drop; 2049 2050 tp->irs = th->th_seq; 2051 tcp_rcvseqinit(tp); 2052 if (thflags & TH_ACK) { 2053 int tfo_partial_ack = 0; 2054 2055 TCPSTAT_INC(tcps_connects); 2056 soisconnected(so); 2057 #ifdef MAC 2058 mac_socketpeer_set_from_mbuf(m, so); 2059 #endif 2060 /* Do window scaling on this connection? */ 2061 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2062 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2063 tp->rcv_scale = tp->request_r_scale; 2064 } 2065 tp->rcv_adv += min(tp->rcv_wnd, 2066 TCP_MAXWIN << tp->rcv_scale); 2067 tp->snd_una++; /* SYN is acked */ 2068 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2069 tp->snd_nxt = tp->snd_una; 2070 /* 2071 * If not all the data that was sent in the TFO SYN 2072 * has been acked, resend the remainder right away. 2073 */ 2074 if ((tp->t_flags & TF_FASTOPEN) && 2075 (tp->snd_una != tp->snd_max)) { 2076 tp->snd_nxt = th->th_ack; 2077 tfo_partial_ack = 1; 2078 } 2079 /* 2080 * If there's data, delay ACK; if there's also a FIN 2081 * ACKNOW will be turned on later. 2082 */ 2083 if (DELAY_ACK(tp, tlen) && tlen != 0 && !tfo_partial_ack) 2084 tcp_timer_activate(tp, TT_DELACK, 2085 tcp_delacktime); 2086 else 2087 tp->t_flags |= TF_ACKNOW; 2088 2089 tcp_ecn_input_syn_sent(tp, thflags, iptos); 2090 2091 /* 2092 * Received <SYN,ACK> in SYN_SENT[*] state. 2093 * Transitions: 2094 * SYN_SENT --> ESTABLISHED 2095 * SYN_SENT* --> FIN_WAIT_1 2096 */ 2097 tp->t_starttime = ticks; 2098 if (tp->t_flags & TF_NEEDFIN) { 2099 tp->t_acktime = ticks; 2100 tcp_state_change(tp, TCPS_FIN_WAIT_1); 2101 tp->t_flags &= ~TF_NEEDFIN; 2102 thflags &= ~TH_SYN; 2103 } else { 2104 tcp_state_change(tp, TCPS_ESTABLISHED); 2105 TCP_PROBE5(connect__established, NULL, tp, 2106 m, tp, th); 2107 cc_conn_init(tp); 2108 tcp_timer_activate(tp, TT_KEEP, 2109 TP_KEEPIDLE(tp)); 2110 } 2111 } else { 2112 /* 2113 * Received initial SYN in SYN-SENT[*] state => 2114 * simultaneous open. 2115 * If it succeeds, connection is * half-synchronized. 2116 * Otherwise, do 3-way handshake: 2117 * SYN-SENT -> SYN-RECEIVED 2118 * SYN-SENT* -> SYN-RECEIVED* 2119 */ 2120 tp->t_flags |= (TF_ACKNOW | TF_NEEDSYN | TF_SONOTCONN); 2121 tcp_timer_activate(tp, TT_REXMT, 0); 2122 tcp_state_change(tp, TCPS_SYN_RECEIVED); 2123 } 2124 2125 /* 2126 * Advance th->th_seq to correspond to first data byte. 2127 * If data, trim to stay within window, 2128 * dropping FIN if necessary. 2129 */ 2130 th->th_seq++; 2131 if (tlen > tp->rcv_wnd) { 2132 todrop = tlen - tp->rcv_wnd; 2133 m_adj(m, -todrop); 2134 tlen = tp->rcv_wnd; 2135 thflags &= ~TH_FIN; 2136 TCPSTAT_INC(tcps_rcvpackafterwin); 2137 TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); 2138 } 2139 tp->snd_wl1 = th->th_seq - 1; 2140 tp->rcv_up = th->th_seq; 2141 /* 2142 * Client side of transaction: already sent SYN and data. 2143 * If the remote host used T/TCP to validate the SYN, 2144 * our data will be ACK'd; if so, enter normal data segment 2145 * processing in the middle of step 5, ack processing. 2146 * Otherwise, goto step 6. 2147 */ 2148 if (thflags & TH_ACK) 2149 goto process_ACK; 2150 2151 goto step6; 2152 } 2153 2154 /* 2155 * States other than LISTEN or SYN_SENT. 2156 * First check the RST flag and sequence number since reset segments 2157 * are exempt from the timestamp and connection count tests. This 2158 * fixes a bug introduced by the Stevens, vol. 2, p. 960 bugfix 2159 * below which allowed reset segments in half the sequence space 2160 * to fall though and be processed (which gives forged reset 2161 * segments with a random sequence number a 50 percent chance of 2162 * killing a connection). 2163 * Then check timestamp, if present. 2164 * Then check the connection count, if present. 2165 * Then check that at least some bytes of segment are within 2166 * receive window. If segment begins before rcv_nxt, 2167 * drop leading data (and SYN); if nothing left, just ack. 2168 */ 2169 if (thflags & TH_RST) { 2170 /* 2171 * RFC5961 Section 3.2 2172 * 2173 * - RST drops connection only if SEG.SEQ == RCV.NXT. 2174 * - If RST is in window, we send challenge ACK. 2175 * 2176 * Note: to take into account delayed ACKs, we should 2177 * test against last_ack_sent instead of rcv_nxt. 2178 * Note 2: we handle special case of closed window, not 2179 * covered by the RFC. 2180 */ 2181 if ((SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 2182 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) || 2183 (tp->rcv_wnd == 0 && tp->last_ack_sent == th->th_seq)) { 2184 KASSERT(tp->t_state != TCPS_SYN_SENT, 2185 ("%s: TH_RST for TCPS_SYN_SENT th %p tp %p", 2186 __func__, th, tp)); 2187 2188 if (V_tcp_insecure_rst || 2189 tp->last_ack_sent == th->th_seq) { 2190 TCPSTAT_INC(tcps_drops); 2191 /* Drop the connection. */ 2192 switch (tp->t_state) { 2193 case TCPS_SYN_RECEIVED: 2194 so->so_error = ECONNREFUSED; 2195 goto close; 2196 case TCPS_ESTABLISHED: 2197 case TCPS_FIN_WAIT_1: 2198 case TCPS_FIN_WAIT_2: 2199 case TCPS_CLOSE_WAIT: 2200 case TCPS_CLOSING: 2201 case TCPS_LAST_ACK: 2202 so->so_error = ECONNRESET; 2203 close: 2204 /* FALLTHROUGH */ 2205 default: 2206 tcp_log_end_status(tp, TCP_EI_STATUS_CLIENT_RST); 2207 tp = tcp_close(tp); 2208 } 2209 } else { 2210 TCPSTAT_INC(tcps_badrst); 2211 tcp_send_challenge_ack(tp, th, m); 2212 m = NULL; 2213 } 2214 } 2215 goto drop; 2216 } 2217 2218 /* 2219 * RFC5961 Section 4.2 2220 * Send challenge ACK for any SYN in synchronized state. 2221 */ 2222 if ((thflags & TH_SYN) && tp->t_state != TCPS_SYN_SENT && 2223 tp->t_state != TCPS_SYN_RECEIVED) { 2224 TCPSTAT_INC(tcps_badsyn); 2225 if (V_tcp_insecure_syn && 2226 SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 2227 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) { 2228 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 2229 tp = tcp_drop(tp, ECONNRESET); 2230 rstreason = BANDLIM_UNLIMITED; 2231 } else { 2232 tcp_ecn_input_syn_sent(tp, thflags, iptos); 2233 tcp_send_challenge_ack(tp, th, m); 2234 m = NULL; 2235 } 2236 goto drop; 2237 } 2238 2239 /* 2240 * RFC 1323 PAWS: If we have a timestamp reply on this segment 2241 * and it's less than ts_recent, drop it. 2242 */ 2243 if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent && 2244 TSTMP_LT(to.to_tsval, tp->ts_recent)) { 2245 /* Check to see if ts_recent is over 24 days old. */ 2246 if (tcp_ts_getticks() - tp->ts_recent_age > TCP_PAWS_IDLE) { 2247 /* 2248 * Invalidate ts_recent. If this segment updates 2249 * ts_recent, the age will be reset later and ts_recent 2250 * will get a valid value. If it does not, setting 2251 * ts_recent to zero will at least satisfy the 2252 * requirement that zero be placed in the timestamp 2253 * echo reply when ts_recent isn't valid. The 2254 * age isn't reset until we get a valid ts_recent 2255 * because we don't want out-of-order segments to be 2256 * dropped when ts_recent is old. 2257 */ 2258 tp->ts_recent = 0; 2259 } else { 2260 TCPSTAT_INC(tcps_rcvduppack); 2261 TCPSTAT_ADD(tcps_rcvdupbyte, tlen); 2262 TCPSTAT_INC(tcps_pawsdrop); 2263 if (tlen) 2264 goto dropafterack; 2265 goto drop; 2266 } 2267 } 2268 2269 /* 2270 * In the SYN-RECEIVED state, validate that the packet belongs to 2271 * this connection before trimming the data to fit the receive 2272 * window. Check the sequence number versus IRS since we know 2273 * the sequence numbers haven't wrapped. This is a partial fix 2274 * for the "LAND" DoS attack. 2275 */ 2276 if (tp->t_state == TCPS_SYN_RECEIVED && SEQ_LT(th->th_seq, tp->irs)) { 2277 rstreason = BANDLIM_RST_OPENPORT; 2278 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 2279 goto dropwithreset; 2280 } 2281 2282 todrop = tp->rcv_nxt - th->th_seq; 2283 if (todrop > 0) { 2284 if (thflags & TH_SYN) { 2285 thflags &= ~TH_SYN; 2286 th->th_seq++; 2287 if (th->th_urp > 1) 2288 th->th_urp--; 2289 else 2290 thflags &= ~TH_URG; 2291 todrop--; 2292 } 2293 /* 2294 * Following if statement from Stevens, vol. 2, p. 960. 2295 */ 2296 if (todrop > tlen 2297 || (todrop == tlen && (thflags & TH_FIN) == 0)) { 2298 /* 2299 * Any valid FIN must be to the left of the window. 2300 * At this point the FIN must be a duplicate or out 2301 * of sequence; drop it. 2302 */ 2303 thflags &= ~TH_FIN; 2304 2305 /* 2306 * Send an ACK to resynchronize and drop any data. 2307 * But keep on processing for RST or ACK. 2308 */ 2309 tp->t_flags |= TF_ACKNOW; 2310 todrop = tlen; 2311 TCPSTAT_INC(tcps_rcvduppack); 2312 TCPSTAT_ADD(tcps_rcvdupbyte, todrop); 2313 } else { 2314 TCPSTAT_INC(tcps_rcvpartduppack); 2315 TCPSTAT_ADD(tcps_rcvpartdupbyte, todrop); 2316 } 2317 /* 2318 * DSACK - add SACK block for dropped range 2319 */ 2320 if ((todrop > 0) && (tp->t_flags & TF_SACK_PERMIT)) { 2321 tcp_update_sack_list(tp, th->th_seq, 2322 th->th_seq + todrop); 2323 /* 2324 * ACK now, as the next in-sequence segment 2325 * will clear the DSACK block again 2326 */ 2327 tp->t_flags |= TF_ACKNOW; 2328 } 2329 drop_hdrlen += todrop; /* drop from the top afterwards */ 2330 th->th_seq += todrop; 2331 tlen -= todrop; 2332 if (th->th_urp > todrop) 2333 th->th_urp -= todrop; 2334 else { 2335 thflags &= ~TH_URG; 2336 th->th_urp = 0; 2337 } 2338 } 2339 2340 /* 2341 * If new data are received on a connection after the 2342 * user processes are gone, then RST the other end if 2343 * no FIN has been processed. 2344 */ 2345 if ((tp->t_flags & TF_CLOSED) && tlen > 0 && 2346 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2347 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 2348 log(LOG_DEBUG, "%s; %s: %s: Received %d bytes of data " 2349 "after socket was closed, " 2350 "sending RST and removing tcpcb\n", 2351 s, __func__, tcpstates[tp->t_state], tlen); 2352 free(s, M_TCPLOG); 2353 } 2354 tcp_log_end_status(tp, TCP_EI_STATUS_DATA_A_CLOSE); 2355 /* tcp_close will kill the inp pre-log the Reset */ 2356 tcp_log_end_status(tp, TCP_EI_STATUS_SERVER_RST); 2357 tp = tcp_close(tp); 2358 TCPSTAT_INC(tcps_rcvafterclose); 2359 rstreason = BANDLIM_UNLIMITED; 2360 goto dropwithreset; 2361 } 2362 2363 /* 2364 * If segment ends after window, drop trailing data 2365 * (and PUSH and FIN); if nothing left, just ACK. 2366 */ 2367 todrop = (th->th_seq + tlen) - (tp->rcv_nxt + tp->rcv_wnd); 2368 if (todrop > 0) { 2369 TCPSTAT_INC(tcps_rcvpackafterwin); 2370 if (todrop >= tlen) { 2371 TCPSTAT_ADD(tcps_rcvbyteafterwin, tlen); 2372 /* 2373 * If window is closed can only take segments at 2374 * window edge, and have to drop data and PUSH from 2375 * incoming segments. Continue processing, but 2376 * remember to ack. Otherwise, drop segment 2377 * and ack. 2378 */ 2379 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 2380 tp->t_flags |= TF_ACKNOW; 2381 TCPSTAT_INC(tcps_rcvwinprobe); 2382 } else 2383 goto dropafterack; 2384 } else 2385 TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); 2386 m_adj(m, -todrop); 2387 tlen -= todrop; 2388 thflags &= ~(TH_PUSH|TH_FIN); 2389 } 2390 2391 /* 2392 * If last ACK falls within this segment's sequence numbers, 2393 * record its timestamp. 2394 * NOTE: 2395 * 1) That the test incorporates suggestions from the latest 2396 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 2397 * 2) That updating only on newer timestamps interferes with 2398 * our earlier PAWS tests, so this check should be solely 2399 * predicated on the sequence space of this segment. 2400 * 3) That we modify the segment boundary check to be 2401 * Last.ACK.Sent <= SEG.SEQ + SEG.Len 2402 * instead of RFC1323's 2403 * Last.ACK.Sent < SEG.SEQ + SEG.Len, 2404 * This modified check allows us to overcome RFC1323's 2405 * limitations as described in Stevens TCP/IP Illustrated 2406 * Vol. 2 p.869. In such cases, we can still calculate the 2407 * RTT correctly when RCV.NXT == Last.ACK.Sent. 2408 */ 2409 if ((to.to_flags & TOF_TS) != 0 && 2410 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 2411 SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen + 2412 ((thflags & (TH_SYN|TH_FIN)) != 0))) { 2413 tp->ts_recent_age = tcp_ts_getticks(); 2414 tp->ts_recent = to.to_tsval; 2415 } 2416 2417 /* 2418 * If the ACK bit is off: if in SYN-RECEIVED state or SENDSYN 2419 * flag is on (half-synchronized state), then queue data for 2420 * later processing; else drop segment and return. 2421 */ 2422 if ((thflags & TH_ACK) == 0) { 2423 if (tp->t_state == TCPS_SYN_RECEIVED || 2424 (tp->t_flags & TF_NEEDSYN)) { 2425 if (tp->t_state == TCPS_SYN_RECEIVED && 2426 (tp->t_flags & TF_FASTOPEN)) { 2427 tp->snd_wnd = tiwin; 2428 cc_conn_init(tp); 2429 } 2430 goto step6; 2431 } else if (tp->t_flags & TF_ACKNOW) 2432 goto dropafterack; 2433 else 2434 goto drop; 2435 } 2436 2437 /* 2438 * Ack processing. 2439 */ 2440 if (SEQ_GEQ(tp->snd_una, tp->iss + (TCP_MAXWIN << tp->snd_scale))) { 2441 /* Checking SEG.ACK against ISS is definitely redundant. */ 2442 tp->t_flags2 |= TF2_NO_ISS_CHECK; 2443 } 2444 if (!V_tcp_insecure_ack) { 2445 tcp_seq seq_min; 2446 bool ghost_ack_check; 2447 2448 if (tp->t_flags2 & TF2_NO_ISS_CHECK) { 2449 /* Check for too old ACKs (RFC 5961, Section 5.2). */ 2450 seq_min = tp->snd_una - tp->max_sndwnd; 2451 ghost_ack_check = false; 2452 } else { 2453 if (SEQ_GT(tp->iss + 1, tp->snd_una - tp->max_sndwnd)) { 2454 /* Checking for ghost ACKs is stricter. */ 2455 seq_min = tp->iss + 1; 2456 ghost_ack_check = true; 2457 } else { 2458 /* 2459 * Checking for too old ACKs (RFC 5961, 2460 * Section 5.2) is stricter. 2461 */ 2462 seq_min = tp->snd_una - tp->max_sndwnd; 2463 ghost_ack_check = false; 2464 } 2465 } 2466 if (SEQ_LT(th->th_ack, seq_min)) { 2467 if (ghost_ack_check) 2468 TCPSTAT_INC(tcps_rcvghostack); 2469 else 2470 TCPSTAT_INC(tcps_rcvacktooold); 2471 tcp_send_challenge_ack(tp, th, m); 2472 m = NULL; 2473 goto drop; 2474 } 2475 } 2476 switch (tp->t_state) { 2477 /* 2478 * In SYN_RECEIVED state, the ack ACKs our SYN, so enter 2479 * ESTABLISHED state and continue processing. 2480 * The ACK was checked above. 2481 */ 2482 case TCPS_SYN_RECEIVED: 2483 2484 TCPSTAT_INC(tcps_connects); 2485 if (tp->t_flags & TF_SONOTCONN) { 2486 /* 2487 * Usually SYN_RECEIVED had been created from a LISTEN, 2488 * and solisten_enqueue() has already marked the socket 2489 * layer as connected. If it didn't, which can happen 2490 * only with an accept_filter(9), then the tp is marked 2491 * with TF_SONOTCONN. The other reason for this mark 2492 * to be set is a simultaneous open, a SYN_RECEIVED 2493 * that had been created from SYN_SENT. 2494 */ 2495 tp->t_flags &= ~TF_SONOTCONN; 2496 soisconnected(so); 2497 } 2498 /* Do window scaling? */ 2499 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2500 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2501 tp->rcv_scale = tp->request_r_scale; 2502 } 2503 tp->snd_wnd = tiwin; 2504 /* 2505 * Make transitions: 2506 * SYN-RECEIVED -> ESTABLISHED 2507 * SYN-RECEIVED* -> FIN-WAIT-1 2508 */ 2509 tp->t_starttime = ticks; 2510 if ((tp->t_flags & TF_FASTOPEN) && tp->t_tfo_pending) { 2511 tcp_fastopen_decrement_counter(tp->t_tfo_pending); 2512 tp->t_tfo_pending = NULL; 2513 } 2514 if (tp->t_flags & TF_NEEDFIN) { 2515 tp->t_acktime = ticks; 2516 tcp_state_change(tp, TCPS_FIN_WAIT_1); 2517 tp->t_flags &= ~TF_NEEDFIN; 2518 } else { 2519 tcp_state_change(tp, TCPS_ESTABLISHED); 2520 TCP_PROBE5(accept__established, NULL, tp, 2521 m, tp, th); 2522 /* 2523 * TFO connections call cc_conn_init() during SYN 2524 * processing. Calling it again here for such 2525 * connections is not harmless as it would undo the 2526 * snd_cwnd reduction that occurs when a TFO SYN|ACK 2527 * is retransmitted. 2528 */ 2529 if (!(tp->t_flags & TF_FASTOPEN)) 2530 cc_conn_init(tp); 2531 tcp_timer_activate(tp, TT_KEEP, TP_KEEPIDLE(tp)); 2532 } 2533 /* 2534 * Account for the ACK of our SYN prior to 2535 * regular ACK processing below, except for 2536 * simultaneous SYN, which is handled later. 2537 */ 2538 if (SEQ_GT(th->th_ack, tp->snd_una) && !(tp->t_flags & TF_NEEDSYN)) 2539 incforsyn = 1; 2540 /* 2541 * If segment contains data or ACK, will call tcp_reass() 2542 * later; if not, do so now to pass queued data to user. 2543 */ 2544 if (tlen == 0 && (thflags & TH_FIN) == 0) { 2545 (void) tcp_reass(tp, (struct tcphdr *)0, NULL, 0, 2546 (struct mbuf *)0); 2547 tcp_handle_wakeup(tp); 2548 } 2549 tp->snd_wl1 = th->th_seq - 1; 2550 /* FALLTHROUGH */ 2551 2552 /* 2553 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 2554 * ACKs. If the ack is in the range 2555 * tp->snd_una < th->th_ack <= tp->snd_max 2556 * then advance tp->snd_una to th->th_ack and drop 2557 * data from the retransmission queue. If this ACK reflects 2558 * more up to date window information we update our window information. 2559 */ 2560 case TCPS_ESTABLISHED: 2561 case TCPS_FIN_WAIT_1: 2562 case TCPS_FIN_WAIT_2: 2563 case TCPS_CLOSE_WAIT: 2564 case TCPS_CLOSING: 2565 case TCPS_LAST_ACK: 2566 if (SEQ_GT(th->th_ack, tp->snd_max)) { 2567 TCPSTAT_INC(tcps_rcvacktoomuch); 2568 goto dropafterack; 2569 } 2570 if (tcp_is_sack_recovery(tp, &to)) { 2571 sack_changed = tcp_sack_doack(tp, &to, th->th_ack); 2572 if ((sack_changed != SACK_NOCHANGE) && 2573 (tp->t_flags & TF_LRD)) { 2574 tcp_sack_lost_retransmission(tp, th); 2575 } 2576 } else 2577 /* 2578 * Reset the value so that previous (valid) value 2579 * from the last ack with SACK doesn't get used. 2580 */ 2581 tp->sackhint.sacked_bytes = 0; 2582 2583 #ifdef TCP_HHOOK 2584 /* Run HHOOK_TCP_ESTABLISHED_IN helper hooks. */ 2585 hhook_run_tcp_est_in(tp, th, &to); 2586 #endif 2587 2588 if (SEQ_LEQ(th->th_ack, tp->snd_una)) { 2589 maxseg = tcp_maxseg(tp); 2590 if (tlen == 0 && 2591 (tiwin == tp->snd_wnd || 2592 (tp->t_flags & TF_SACK_PERMIT))) { 2593 /* 2594 * If this is the first time we've seen a 2595 * FIN from the remote, this is not a 2596 * duplicate and it needs to be processed 2597 * normally. This happens during a 2598 * simultaneous close. 2599 */ 2600 if ((thflags & TH_FIN) && 2601 (TCPS_HAVERCVDFIN(tp->t_state) == 0)) { 2602 tp->t_dupacks = 0; 2603 break; 2604 } 2605 TCPSTAT_INC(tcps_rcvdupack); 2606 /* 2607 * If we have outstanding data (other than 2608 * a window probe), this is a completely 2609 * duplicate ack (ie, window info didn't 2610 * change and FIN isn't set), 2611 * the ack is the biggest we've 2612 * seen and we've seen exactly our rexmt 2613 * threshold of them, assume a packet 2614 * has been dropped and retransmit it. 2615 * Kludge snd_nxt & the congestion 2616 * window so we send only this one 2617 * packet. 2618 * 2619 * We know we're losing at the current 2620 * window size so do congestion avoidance 2621 * (set ssthresh to half the current window 2622 * and pull our congestion window back to 2623 * the new ssthresh). 2624 * 2625 * Dup acks mean that packets have left the 2626 * network (they're now cached at the receiver) 2627 * so bump cwnd by the amount in the receiver 2628 * to keep a constant cwnd packets in the 2629 * network. 2630 * 2631 * When using TCP ECN, notify the peer that 2632 * we reduced the cwnd. 2633 */ 2634 /* 2635 * Following 2 kinds of acks should not affect 2636 * dupack counting: 2637 * 1) Old acks 2638 * 2) Acks with SACK but without any new SACK 2639 * information in them. These could result from 2640 * any anomaly in the network like a switch 2641 * duplicating packets or a possible DoS attack. 2642 */ 2643 if (th->th_ack != tp->snd_una || 2644 (tcp_is_sack_recovery(tp, &to) && 2645 (sack_changed == SACK_NOCHANGE))) { 2646 break; 2647 } else if (!tcp_timer_active(tp, TT_REXMT)) { 2648 tp->t_dupacks = 0; 2649 } else if (++tp->t_dupacks > tcprexmtthresh || 2650 IN_FASTRECOVERY(tp->t_flags)) { 2651 cc_ack_received(tp, th, nsegs, 2652 CC_DUPACK); 2653 if (V_tcp_do_prr && 2654 IN_FASTRECOVERY(tp->t_flags) && 2655 (tp->t_flags & TF_SACK_PERMIT)) { 2656 tcp_do_prr_ack(tp, th, &to, 2657 sack_changed, &maxseg); 2658 } else if (tcp_is_sack_recovery(tp, &to) && 2659 IN_FASTRECOVERY(tp->t_flags)) { 2660 int awnd; 2661 2662 /* 2663 * Compute the amount of data in flight first. 2664 * We can inject new data into the pipe iff 2665 * we have less than 1/2 the original window's 2666 * worth of data in flight. 2667 */ 2668 if (V_tcp_do_newsack) { 2669 awnd = tcp_compute_pipe(tp); 2670 } else { 2671 awnd = (tp->snd_nxt - tp->snd_fack) + 2672 tp->sackhint.sack_bytes_rexmit; 2673 } 2674 if (awnd < tp->snd_ssthresh) { 2675 tp->snd_cwnd += maxseg; 2676 if (tp->snd_cwnd > tp->snd_ssthresh) 2677 tp->snd_cwnd = tp->snd_ssthresh; 2678 } 2679 } else { 2680 tp->snd_cwnd += maxseg; 2681 } 2682 (void) tcp_output(tp); 2683 goto drop; 2684 } else if (tp->t_dupacks == tcprexmtthresh || 2685 (tp->t_flags & TF_SACK_PERMIT && 2686 V_tcp_do_newsack && 2687 tp->sackhint.sacked_bytes > 2688 (tcprexmtthresh - 1) * maxseg)) { 2689 enter_recovery: 2690 /* 2691 * Above is the RFC6675 trigger condition of 2692 * more than (dupthresh-1)*maxseg sacked data. 2693 * If the count of holes in the 2694 * scoreboard is >= dupthresh, we could 2695 * also enter loss recovery, but don't 2696 * have that value readily available. 2697 */ 2698 tp->t_dupacks = tcprexmtthresh; 2699 tcp_seq onxt = tp->snd_nxt; 2700 2701 /* 2702 * If we're doing sack, or prr, check 2703 * to see if we're already in sack 2704 * recovery. If we're not doing sack, 2705 * check to see if we're in newreno 2706 * recovery. 2707 */ 2708 if (V_tcp_do_prr || 2709 (tp->t_flags & TF_SACK_PERMIT)) { 2710 if (IN_FASTRECOVERY(tp->t_flags)) { 2711 tp->t_dupacks = 0; 2712 break; 2713 } 2714 } else { 2715 if (SEQ_LEQ(th->th_ack, 2716 tp->snd_recover)) { 2717 tp->t_dupacks = 0; 2718 break; 2719 } 2720 } 2721 /* Congestion signal before ack. */ 2722 cc_cong_signal(tp, th, CC_NDUPACK); 2723 cc_ack_received(tp, th, nsegs, 2724 CC_DUPACK); 2725 tcp_timer_activate(tp, TT_REXMT, 0); 2726 tp->t_rtttime = 0; 2727 if (V_tcp_do_prr) { 2728 /* 2729 * snd_ssthresh is already updated by 2730 * cc_cong_signal. 2731 */ 2732 if (tcp_is_sack_recovery(tp, &to)) { 2733 /* 2734 * Exclude Limited Transmit 2735 * segments here 2736 */ 2737 tp->sackhint.prr_delivered = 2738 maxseg; 2739 } else { 2740 tp->sackhint.prr_delivered = 2741 imin(tp->snd_max - tp->snd_una, 2742 imin(INT_MAX / 65536, 2743 tp->t_dupacks) * maxseg); 2744 } 2745 tp->sackhint.recover_fs = max(1, 2746 tp->snd_nxt - tp->snd_una); 2747 } 2748 if (tcp_is_sack_recovery(tp, &to)) { 2749 TCPSTAT_INC(tcps_sack_recovery_episode); 2750 tp->snd_recover = tp->snd_nxt; 2751 tp->snd_cwnd = maxseg; 2752 (void) tcp_output(tp); 2753 if (SEQ_GT(th->th_ack, tp->snd_una)) { 2754 goto resume_partialack; 2755 } 2756 goto drop; 2757 } 2758 tp->snd_nxt = th->th_ack; 2759 tp->snd_cwnd = maxseg; 2760 (void) tcp_output(tp); 2761 KASSERT(tp->snd_limited <= 2, 2762 ("%s: tp->snd_limited too big", 2763 __func__)); 2764 tp->snd_cwnd = tp->snd_ssthresh + 2765 maxseg * 2766 (tp->t_dupacks - tp->snd_limited); 2767 if (SEQ_GT(onxt, tp->snd_nxt)) 2768 tp->snd_nxt = onxt; 2769 goto drop; 2770 } else if (V_tcp_do_rfc3042) { 2771 /* 2772 * Process first and second duplicate 2773 * ACKs. Each indicates a segment 2774 * leaving the network, creating room 2775 * for more. Make sure we can send a 2776 * packet on reception of each duplicate 2777 * ACK by increasing snd_cwnd by one 2778 * segment. Restore the original 2779 * snd_cwnd after packet transmission. 2780 */ 2781 cc_ack_received(tp, th, nsegs, CC_DUPACK); 2782 uint32_t oldcwnd = tp->snd_cwnd; 2783 tcp_seq oldsndmax = tp->snd_max; 2784 u_int sent; 2785 int avail; 2786 2787 KASSERT(tp->t_dupacks == 1 || 2788 tp->t_dupacks == 2, 2789 ("%s: dupacks not 1 or 2", 2790 __func__)); 2791 if (tp->t_dupacks == 1) 2792 tp->snd_limited = 0; 2793 tp->snd_cwnd = 2794 (tp->snd_nxt - tp->snd_una) + 2795 (tp->t_dupacks - tp->snd_limited) * 2796 maxseg; 2797 /* 2798 * Only call tcp_output when there 2799 * is new data available to be sent 2800 * or we need to send an ACK. 2801 */ 2802 SOCKBUF_LOCK(&so->so_snd); 2803 avail = sbavail(&so->so_snd); 2804 SOCKBUF_UNLOCK(&so->so_snd); 2805 if (tp->t_flags & TF_ACKNOW || 2806 (avail >= 2807 SEQ_SUB(tp->snd_nxt, tp->snd_una))) { 2808 (void) tcp_output(tp); 2809 } 2810 sent = SEQ_SUB(tp->snd_max, oldsndmax); 2811 if (sent > maxseg) { 2812 KASSERT((tp->t_dupacks == 2 && 2813 tp->snd_limited == 0) || 2814 (sent == maxseg + 1 && 2815 tp->t_flags & TF_SENTFIN), 2816 ("%s: sent too much", 2817 __func__)); 2818 tp->snd_limited = 2; 2819 } else if (sent > 0) { 2820 ++tp->snd_limited; 2821 } 2822 tp->snd_cwnd = oldcwnd; 2823 goto drop; 2824 } 2825 } 2826 break; 2827 } else { 2828 /* 2829 * This ack is advancing the left edge, reset the 2830 * counter. 2831 */ 2832 tp->t_dupacks = 0; 2833 /* 2834 * If this ack also has new SACK info, increment the 2835 * counter as per rfc6675. The variable 2836 * sack_changed tracks all changes to the SACK 2837 * scoreboard, including when partial ACKs without 2838 * SACK options are received, and clear the scoreboard 2839 * from the left side. Such partial ACKs should not be 2840 * counted as dupacks here. 2841 */ 2842 if (tcp_is_sack_recovery(tp, &to) && 2843 (sack_changed != SACK_NOCHANGE)) { 2844 tp->t_dupacks++; 2845 /* limit overhead by setting maxseg last */ 2846 if (!IN_FASTRECOVERY(tp->t_flags) && 2847 (tp->sackhint.sacked_bytes > 2848 ((tcprexmtthresh - 1) * 2849 (maxseg = tcp_maxseg(tp))))) { 2850 goto enter_recovery; 2851 } 2852 } 2853 } 2854 2855 resume_partialack: 2856 KASSERT(SEQ_GT(th->th_ack, tp->snd_una), 2857 ("%s: th_ack <= snd_una", __func__)); 2858 2859 /* 2860 * If the congestion window was inflated to account 2861 * for the other side's cached packets, retract it. 2862 */ 2863 if (SEQ_LT(th->th_ack, tp->snd_recover)) { 2864 if (IN_FASTRECOVERY(tp->t_flags)) { 2865 if (tp->t_flags & TF_SACK_PERMIT) { 2866 if (V_tcp_do_prr && 2867 (to.to_flags & TOF_SACK)) { 2868 tcp_timer_activate(tp, 2869 TT_REXMT, 0); 2870 tp->t_rtttime = 0; 2871 tcp_do_prr_ack(tp, th, &to, 2872 sack_changed, &maxseg); 2873 tp->t_flags |= TF_ACKNOW; 2874 (void) tcp_output(tp); 2875 } else { 2876 tcp_sack_partialack(tp, th, 2877 &maxseg); 2878 } 2879 } else { 2880 tcp_newreno_partial_ack(tp, th); 2881 } 2882 } else if (IN_CONGRECOVERY(tp->t_flags) && 2883 (V_tcp_do_prr)) { 2884 tp->sackhint.delivered_data = 2885 BYTES_THIS_ACK(tp, th); 2886 tp->snd_fack = th->th_ack; 2887 /* 2888 * During ECN cwnd reduction 2889 * always use PRR-SSRB 2890 */ 2891 tcp_do_prr_ack(tp, th, &to, SACK_CHANGE, 2892 &maxseg); 2893 (void) tcp_output(tp); 2894 } 2895 } 2896 /* 2897 * If we reach this point, ACK is not a duplicate, 2898 * i.e., it ACKs something we sent. 2899 */ 2900 if (tp->t_flags & TF_NEEDSYN) { 2901 /* 2902 * T/TCP: Connection was half-synchronized, and our 2903 * SYN has been ACK'd (so connection is now fully 2904 * synchronized). Go to non-starred state, 2905 * increment snd_una for ACK of SYN, and check if 2906 * we can do window scaling. 2907 */ 2908 tp->t_flags &= ~TF_NEEDSYN; 2909 tp->snd_una++; 2910 /* Do window scaling? */ 2911 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2912 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2913 tp->rcv_scale = tp->request_r_scale; 2914 /* Send window already scaled. */ 2915 } 2916 } 2917 2918 process_ACK: 2919 INP_WLOCK_ASSERT(inp); 2920 2921 /* 2922 * Adjust for the SYN bit in sequence space, 2923 * but don't account for it in cwnd calculations. 2924 * This is for the SYN_RECEIVED, non-simultaneous 2925 * SYN case. SYN_SENT and simultaneous SYN are 2926 * treated elsewhere. 2927 */ 2928 if (incforsyn) 2929 tp->snd_una++; 2930 acked = BYTES_THIS_ACK(tp, th); 2931 KASSERT(acked >= 0, ("%s: acked unexepectedly negative " 2932 "(tp->snd_una=%u, th->th_ack=%u, tp=%p, m=%p)", __func__, 2933 tp->snd_una, th->th_ack, tp, m)); 2934 TCPSTAT_ADD(tcps_rcvackpack, nsegs); 2935 TCPSTAT_ADD(tcps_rcvackbyte, acked); 2936 2937 /* 2938 * If we just performed our first retransmit, and the ACK 2939 * arrives within our recovery window, then it was a mistake 2940 * to do the retransmit in the first place. Recover our 2941 * original cwnd and ssthresh, and proceed to transmit where 2942 * we left off. 2943 */ 2944 if (tp->t_rxtshift == 1 && 2945 tp->t_flags & TF_PREVVALID && 2946 tp->t_badrxtwin != 0 && 2947 to.to_flags & TOF_TS && 2948 to.to_tsecr != 0 && 2949 TSTMP_LT(to.to_tsecr, tp->t_badrxtwin)) 2950 cc_cong_signal(tp, th, CC_RTO_ERR); 2951 2952 /* 2953 * If we have a timestamp reply, update smoothed 2954 * round trip time. If no timestamp is present but 2955 * transmit timer is running and timed sequence 2956 * number was acked, update smoothed round trip time. 2957 * Since we now have an rtt measurement, cancel the 2958 * timer backoff (cf., Phil Karn's retransmit alg.). 2959 * Recompute the initial retransmit timer. 2960 * 2961 * Some boxes send broken timestamp replies 2962 * during the SYN+ACK phase, ignore 2963 * timestamps of 0 or we could calculate a 2964 * huge RTT and blow up the retransmit timer. 2965 */ 2966 if ((to.to_flags & TOF_TS) != 0 && to.to_tsecr) { 2967 uint32_t t; 2968 2969 t = tcp_ts_getticks() - to.to_tsecr; 2970 if (!tp->t_rttlow || tp->t_rttlow > t) 2971 tp->t_rttlow = t; 2972 tcp_xmit_timer(tp, TCP_TS_TO_TICKS(t) + 1); 2973 } else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) { 2974 if (!tp->t_rttlow || tp->t_rttlow > ticks - tp->t_rtttime) 2975 tp->t_rttlow = ticks - tp->t_rtttime; 2976 tcp_xmit_timer(tp, ticks - tp->t_rtttime); 2977 } 2978 2979 SOCKBUF_LOCK(&so->so_snd); 2980 /* 2981 * Clear t_acktime if remote side has ACKd all data in the 2982 * socket buffer and FIN (if applicable). 2983 * Otherwise, update t_acktime if we received a sufficiently 2984 * large ACK. 2985 */ 2986 if ((tp->t_state <= TCPS_CLOSE_WAIT && 2987 acked == sbavail(&so->so_snd)) || 2988 acked > sbavail(&so->so_snd)) 2989 tp->t_acktime = 0; 2990 else if (acked > 1) 2991 tp->t_acktime = ticks; 2992 2993 /* 2994 * If all outstanding data is acked, stop retransmit 2995 * timer and remember to restart (more output or persist). 2996 * If there is more data to be acked, restart retransmit 2997 * timer, using current (possibly backed-off) value. 2998 */ 2999 if (th->th_ack == tp->snd_max) { 3000 tcp_timer_activate(tp, TT_REXMT, 0); 3001 needoutput = 1; 3002 } else if (!tcp_timer_active(tp, TT_PERSIST)) 3003 tcp_timer_activate(tp, TT_REXMT, TP_RXTCUR(tp)); 3004 3005 /* 3006 * If no data (only SYN) was ACK'd, 3007 * skip rest of ACK processing. 3008 */ 3009 if (acked == 0) { 3010 SOCKBUF_UNLOCK(&so->so_snd); 3011 goto step6; 3012 } 3013 3014 /* 3015 * Let the congestion control algorithm update congestion 3016 * control related information. This typically means increasing 3017 * the congestion window. 3018 */ 3019 cc_ack_received(tp, th, nsegs, CC_ACK); 3020 3021 if (acked > sbavail(&so->so_snd)) { 3022 if (tp->snd_wnd >= sbavail(&so->so_snd)) 3023 tp->snd_wnd -= sbavail(&so->so_snd); 3024 else 3025 tp->snd_wnd = 0; 3026 mfree = sbcut_locked(&so->so_snd, 3027 (int)sbavail(&so->so_snd)); 3028 ourfinisacked = 1; 3029 } else { 3030 mfree = sbcut_locked(&so->so_snd, acked); 3031 if (tp->snd_wnd >= (uint32_t) acked) 3032 tp->snd_wnd -= acked; 3033 else 3034 tp->snd_wnd = 0; 3035 ourfinisacked = 0; 3036 } 3037 /* NB: sowwakeup_locked() does an implicit unlock. */ 3038 sowwakeup_locked(so); 3039 m_freem(mfree); 3040 /* Detect una wraparound. */ 3041 if (!IN_RECOVERY(tp->t_flags) && 3042 SEQ_GT(tp->snd_una, tp->snd_recover) && 3043 SEQ_LEQ(th->th_ack, tp->snd_recover)) 3044 tp->snd_recover = th->th_ack - 1; 3045 tp->snd_una = th->th_ack; 3046 if (IN_RECOVERY(tp->t_flags) && 3047 SEQ_GEQ(th->th_ack, tp->snd_recover)) { 3048 cc_post_recovery(tp, th); 3049 } 3050 if (tp->t_flags & TF_SACK_PERMIT) { 3051 if (SEQ_GT(tp->snd_una, tp->snd_recover)) 3052 tp->snd_recover = tp->snd_una; 3053 } 3054 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 3055 tp->snd_nxt = tp->snd_una; 3056 3057 switch (tp->t_state) { 3058 /* 3059 * In FIN_WAIT_1 STATE in addition to the processing 3060 * for the ESTABLISHED state if our FIN is now acknowledged 3061 * then enter FIN_WAIT_2. 3062 */ 3063 case TCPS_FIN_WAIT_1: 3064 if (ourfinisacked) { 3065 /* 3066 * If we can't receive any more 3067 * data, then closing user can proceed. 3068 * Starting the timer is contrary to the 3069 * specification, but if we don't get a FIN 3070 * we'll hang forever. 3071 */ 3072 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 3073 tcp_free_sackholes(tp); 3074 soisdisconnected(so); 3075 tcp_timer_activate(tp, TT_2MSL, 3076 (tcp_fast_finwait2_recycle ? 3077 tcp_finwait2_timeout : 3078 TP_MAXIDLE(tp))); 3079 } 3080 tcp_state_change(tp, TCPS_FIN_WAIT_2); 3081 } 3082 break; 3083 3084 /* 3085 * In CLOSING STATE in addition to the processing for 3086 * the ESTABLISHED state if the ACK acknowledges our FIN 3087 * then enter the TIME-WAIT state, otherwise ignore 3088 * the segment. 3089 */ 3090 case TCPS_CLOSING: 3091 if (ourfinisacked) { 3092 tcp_twstart(tp); 3093 m_freem(m); 3094 return; 3095 } 3096 break; 3097 3098 /* 3099 * In LAST_ACK, we may still be waiting for data to drain 3100 * and/or to be acked, as well as for the ack of our FIN. 3101 * If our FIN is now acknowledged, delete the TCB, 3102 * enter the closed state and return. 3103 */ 3104 case TCPS_LAST_ACK: 3105 if (ourfinisacked) { 3106 tp = tcp_close(tp); 3107 goto drop; 3108 } 3109 break; 3110 } 3111 } 3112 3113 step6: 3114 INP_WLOCK_ASSERT(inp); 3115 3116 /* 3117 * Update window information. 3118 * Don't look at window if no ACK: TAC's send garbage on first SYN. 3119 */ 3120 if ((thflags & TH_ACK) && 3121 (SEQ_LT(tp->snd_wl1, th->th_seq) || 3122 (tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) || 3123 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) { 3124 /* keep track of pure window updates */ 3125 if (tlen == 0 && 3126 tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) 3127 TCPSTAT_INC(tcps_rcvwinupd); 3128 tp->snd_wnd = tiwin; 3129 tp->snd_wl1 = th->th_seq; 3130 tp->snd_wl2 = th->th_ack; 3131 if (tp->snd_wnd > tp->max_sndwnd) 3132 tp->max_sndwnd = tp->snd_wnd; 3133 needoutput = 1; 3134 } 3135 3136 /* 3137 * Process segments with URG. 3138 */ 3139 if ((thflags & TH_URG) && th->th_urp && 3140 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3141 /* 3142 * This is a kludge, but if we receive and accept 3143 * random urgent pointers, we'll crash in 3144 * soreceive. It's hard to imagine someone 3145 * actually wanting to send this much urgent data. 3146 */ 3147 SOCKBUF_LOCK(&so->so_rcv); 3148 if (th->th_urp + sbavail(&so->so_rcv) > sb_max) { 3149 th->th_urp = 0; /* XXX */ 3150 thflags &= ~TH_URG; /* XXX */ 3151 SOCKBUF_UNLOCK(&so->so_rcv); /* XXX */ 3152 goto dodata; /* XXX */ 3153 } 3154 /* 3155 * If this segment advances the known urgent pointer, 3156 * then mark the data stream. This should not happen 3157 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 3158 * a FIN has been received from the remote side. 3159 * In these states we ignore the URG. 3160 * 3161 * According to RFC961 (Assigned Protocols), 3162 * the urgent pointer points to the last octet 3163 * of urgent data. We continue, however, 3164 * to consider it to indicate the first octet 3165 * of data past the urgent section as the original 3166 * spec states (in one of two places). 3167 */ 3168 if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) { 3169 tp->rcv_up = th->th_seq + th->th_urp; 3170 so->so_oobmark = sbavail(&so->so_rcv) + 3171 (tp->rcv_up - tp->rcv_nxt) - 1; 3172 if (so->so_oobmark == 0) 3173 so->so_rcv.sb_state |= SBS_RCVATMARK; 3174 sohasoutofband(so); 3175 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); 3176 } 3177 SOCKBUF_UNLOCK(&so->so_rcv); 3178 /* 3179 * Remove out of band data so doesn't get presented to user. 3180 * This can happen independent of advancing the URG pointer, 3181 * but if two URG's are pending at once, some out-of-band 3182 * data may creep in... ick. 3183 */ 3184 if (th->th_urp <= (uint32_t)tlen && 3185 !(so->so_options & SO_OOBINLINE)) { 3186 /* hdr drop is delayed */ 3187 tcp_pulloutofband(so, th, m, drop_hdrlen); 3188 } 3189 } else { 3190 /* 3191 * If no out of band data is expected, 3192 * pull receive urgent pointer along 3193 * with the receive window. 3194 */ 3195 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) 3196 tp->rcv_up = tp->rcv_nxt; 3197 } 3198 dodata: /* XXX */ 3199 INP_WLOCK_ASSERT(inp); 3200 3201 /* 3202 * Process the segment text, merging it into the TCP sequencing queue, 3203 * and arranging for acknowledgment of receipt if necessary. 3204 * This process logically involves adjusting tp->rcv_wnd as data 3205 * is presented to the user (this happens in tcp_usrreq.c, 3206 * case PRU_RCVD). If a FIN has already been received on this 3207 * connection then we just ignore the text. 3208 */ 3209 tfo_syn = ((tp->t_state == TCPS_SYN_RECEIVED) && 3210 (tp->t_flags & TF_FASTOPEN)); 3211 if ((tlen || (thflags & TH_FIN) || (tfo_syn && tlen > 0)) && 3212 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3213 tcp_seq save_start = th->th_seq; 3214 tcp_seq save_rnxt = tp->rcv_nxt; 3215 int save_tlen = tlen; 3216 m_adj(m, drop_hdrlen); /* delayed header drop */ 3217 /* 3218 * Insert segment which includes th into TCP reassembly queue 3219 * with control block tp. Set thflags to whether reassembly now 3220 * includes a segment with FIN. This handles the common case 3221 * inline (segment is the next to be received on an established 3222 * connection, and the queue is empty), avoiding linkage into 3223 * and removal from the queue and repetition of various 3224 * conversions. 3225 * Set DELACK for segments received in order, but ack 3226 * immediately when segments are out of order (so 3227 * fast retransmit can work). 3228 */ 3229 if (th->th_seq == tp->rcv_nxt && 3230 SEGQ_EMPTY(tp) && 3231 (TCPS_HAVEESTABLISHED(tp->t_state) || 3232 tfo_syn)) { 3233 if (DELAY_ACK(tp, tlen) || tfo_syn) 3234 tp->t_flags |= TF_DELACK; 3235 else 3236 tp->t_flags |= TF_ACKNOW; 3237 tp->rcv_nxt += tlen; 3238 if (tlen && 3239 ((tp->t_flags2 & TF2_FBYTES_COMPLETE) == 0) && 3240 (tp->t_fbyte_in == 0)) { 3241 tp->t_fbyte_in = ticks; 3242 if (tp->t_fbyte_in == 0) 3243 tp->t_fbyte_in = 1; 3244 if (tp->t_fbyte_out && tp->t_fbyte_in) 3245 tp->t_flags2 |= TF2_FBYTES_COMPLETE; 3246 } 3247 thflags = tcp_get_flags(th) & TH_FIN; 3248 TCPSTAT_INC(tcps_rcvpack); 3249 TCPSTAT_ADD(tcps_rcvbyte, tlen); 3250 SOCKBUF_LOCK(&so->so_rcv); 3251 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) 3252 m_freem(m); 3253 else 3254 sbappendstream_locked(&so->so_rcv, m, 0); 3255 tp->t_flags |= TF_WAKESOR; 3256 } else { 3257 /* 3258 * XXX: Due to the header drop above "th" is 3259 * theoretically invalid by now. Fortunately 3260 * m_adj() doesn't actually frees any mbufs 3261 * when trimming from the head. 3262 */ 3263 tcp_seq temp = save_start; 3264 3265 thflags = tcp_reass(tp, th, &temp, &tlen, m); 3266 tp->t_flags |= TF_ACKNOW; 3267 } 3268 if ((tp->t_flags & TF_SACK_PERMIT) && 3269 (save_tlen > 0) && 3270 TCPS_HAVEESTABLISHED(tp->t_state)) { 3271 if ((tlen == 0) && (SEQ_LT(save_start, save_rnxt))) { 3272 /* 3273 * DSACK actually handled in the fastpath 3274 * above. 3275 */ 3276 tcp_update_sack_list(tp, save_start, 3277 save_start + save_tlen); 3278 } else if ((tlen > 0) && SEQ_GT(tp->rcv_nxt, save_rnxt)) { 3279 if ((tp->rcv_numsacks >= 1) && 3280 (tp->sackblks[0].end == save_start)) { 3281 /* 3282 * Partial overlap, recorded at todrop 3283 * above. 3284 */ 3285 tcp_update_sack_list(tp, 3286 tp->sackblks[0].start, 3287 tp->sackblks[0].end); 3288 } else { 3289 tcp_update_dsack_list(tp, save_start, 3290 save_start + save_tlen); 3291 } 3292 } else if (tlen >= save_tlen) { 3293 /* Update of sackblks. */ 3294 tcp_update_dsack_list(tp, save_start, 3295 save_start + save_tlen); 3296 } else if (tlen > 0) { 3297 tcp_update_dsack_list(tp, save_start, 3298 save_start + tlen); 3299 } 3300 } 3301 tcp_handle_wakeup(tp); 3302 #if 0 3303 /* 3304 * Note the amount of data that peer has sent into 3305 * our window, in order to estimate the sender's 3306 * buffer size. 3307 * XXX: Unused. 3308 */ 3309 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt)) 3310 len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); 3311 else 3312 len = so->so_rcv.sb_hiwat; 3313 #endif 3314 } else { 3315 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 3316 if (tlen > 0) { 3317 if ((thflags & TH_FIN) != 0) { 3318 log(LOG_DEBUG, "%s; %s: %s: " 3319 "Received %d bytes of data and FIN " 3320 "after having received a FIN, " 3321 "just dropping both\n", 3322 s, __func__, 3323 tcpstates[tp->t_state], tlen); 3324 } else { 3325 log(LOG_DEBUG, "%s; %s: %s: " 3326 "Received %d bytes of data " 3327 "after having received a FIN, " 3328 "just dropping it\n", 3329 s, __func__, 3330 tcpstates[tp->t_state], tlen); 3331 } 3332 } else { 3333 if ((thflags & TH_FIN) != 0) { 3334 log(LOG_DEBUG, "%s; %s: %s: " 3335 "Received FIN " 3336 "after having received a FIN, " 3337 "just dropping it\n", 3338 s, __func__, 3339 tcpstates[tp->t_state]); 3340 } 3341 } 3342 free(s, M_TCPLOG); 3343 } 3344 m_freem(m); 3345 thflags &= ~TH_FIN; 3346 } 3347 3348 /* 3349 * If FIN is received ACK the FIN and let the user know 3350 * that the connection is closing. 3351 */ 3352 if (thflags & TH_FIN) { 3353 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3354 /* The socket upcall is handled by socantrcvmore. */ 3355 socantrcvmore(so); 3356 /* 3357 * If connection is half-synchronized 3358 * (ie NEEDSYN flag on) then delay ACK, 3359 * so it may be piggybacked when SYN is sent. 3360 * Otherwise, since we received a FIN then no 3361 * more input can be expected, send ACK now. 3362 */ 3363 if (tp->t_flags & TF_NEEDSYN) 3364 tp->t_flags |= TF_DELACK; 3365 else 3366 tp->t_flags |= TF_ACKNOW; 3367 tp->rcv_nxt++; 3368 } 3369 switch (tp->t_state) { 3370 /* 3371 * In SYN_RECEIVED and ESTABLISHED STATES 3372 * enter the CLOSE_WAIT state. 3373 */ 3374 case TCPS_SYN_RECEIVED: 3375 tp->t_starttime = ticks; 3376 /* FALLTHROUGH */ 3377 case TCPS_ESTABLISHED: 3378 tcp_state_change(tp, TCPS_CLOSE_WAIT); 3379 break; 3380 3381 /* 3382 * If still in FIN_WAIT_1 STATE FIN has not been acked so 3383 * enter the CLOSING state. 3384 */ 3385 case TCPS_FIN_WAIT_1: 3386 tcp_state_change(tp, TCPS_CLOSING); 3387 break; 3388 3389 /* 3390 * In FIN_WAIT_2 state enter the TIME_WAIT state, 3391 * starting the time-wait timer, turning off the other 3392 * standard timers. 3393 */ 3394 case TCPS_FIN_WAIT_2: 3395 tcp_twstart(tp); 3396 return; 3397 } 3398 } 3399 TCP_PROBE3(debug__input, tp, th, m); 3400 3401 /* 3402 * Return any desired output. 3403 */ 3404 if (needoutput || (tp->t_flags & TF_ACKNOW)) { 3405 (void) tcp_output(tp); 3406 } 3407 check_delack: 3408 INP_WLOCK_ASSERT(inp); 3409 3410 if (tp->t_flags & TF_DELACK) { 3411 tp->t_flags &= ~TF_DELACK; 3412 tcp_timer_activate(tp, TT_DELACK, tcp_delacktime); 3413 } 3414 INP_WUNLOCK(inp); 3415 return; 3416 3417 dropafterack: 3418 /* 3419 * Generate an ACK dropping incoming segment if it occupies 3420 * sequence space, where the ACK reflects our state. 3421 * 3422 * We can now skip the test for the RST flag since all 3423 * paths to this code happen after packets containing 3424 * RST have been dropped. 3425 * 3426 * In the SYN-RECEIVED state, don't send an ACK unless the 3427 * segment we received passes the SYN-RECEIVED ACK test. 3428 * If it fails send a RST. This breaks the loop in the 3429 * "LAND" DoS attack, and also prevents an ACK storm 3430 * between two listening ports that have been sent forged 3431 * SYN segments, each with the source address of the other. 3432 */ 3433 if (tp->t_state == TCPS_SYN_RECEIVED && (thflags & TH_ACK) && 3434 (SEQ_GT(tp->snd_una, th->th_ack) || 3435 SEQ_GT(th->th_ack, tp->snd_max)) ) { 3436 rstreason = BANDLIM_RST_OPENPORT; 3437 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 3438 goto dropwithreset; 3439 } 3440 TCP_PROBE3(debug__input, tp, th, m); 3441 tp->t_flags |= TF_ACKNOW; 3442 (void) tcp_output(tp); 3443 INP_WUNLOCK(inp); 3444 m_freem(m); 3445 return; 3446 3447 dropwithreset: 3448 if (tp != NULL) { 3449 tcp_dropwithreset(m, th, tp, tlen, rstreason); 3450 INP_WUNLOCK(inp); 3451 } else 3452 tcp_dropwithreset(m, th, NULL, tlen, rstreason); 3453 return; 3454 3455 drop: 3456 /* 3457 * Drop space held by incoming segment and return. 3458 */ 3459 TCP_PROBE3(debug__input, tp, th, m); 3460 if (tp != NULL) { 3461 INP_WUNLOCK(inp); 3462 } 3463 m_freem(m); 3464 } 3465 3466 /* 3467 * Issue RST and make ACK acceptable to originator of segment. 3468 * The mbuf must still include the original packet header. 3469 * tp may be NULL. 3470 */ 3471 void 3472 tcp_dropwithreset(struct mbuf *m, struct tcphdr *th, struct tcpcb *tp, 3473 int tlen, int rstreason) 3474 { 3475 #ifdef INET 3476 struct ip *ip; 3477 #endif 3478 #ifdef INET6 3479 struct ip6_hdr *ip6; 3480 #endif 3481 3482 if (tp != NULL) { 3483 INP_LOCK_ASSERT(tptoinpcb(tp)); 3484 } 3485 3486 /* Don't bother if destination was broadcast/multicast. */ 3487 if ((tcp_get_flags(th) & TH_RST) || m->m_flags & (M_BCAST|M_MCAST)) 3488 goto drop; 3489 #ifdef INET6 3490 if (mtod(m, struct ip *)->ip_v == 6) { 3491 ip6 = mtod(m, struct ip6_hdr *); 3492 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 3493 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) 3494 goto drop; 3495 /* IPv6 anycast check is done at tcp6_input() */ 3496 } 3497 #endif 3498 #if defined(INET) && defined(INET6) 3499 else 3500 #endif 3501 #ifdef INET 3502 { 3503 ip = mtod(m, struct ip *); 3504 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 3505 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 3506 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || 3507 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 3508 goto drop; 3509 } 3510 #endif 3511 3512 /* Perform bandwidth limiting. */ 3513 if (badport_bandlim(rstreason) < 0) 3514 goto drop; 3515 3516 /* tcp_respond consumes the mbuf chain. */ 3517 if (tcp_get_flags(th) & TH_ACK) { 3518 tcp_respond(tp, mtod(m, void *), th, m, (tcp_seq)0, 3519 th->th_ack, TH_RST); 3520 } else { 3521 if (tcp_get_flags(th) & TH_SYN) 3522 tlen++; 3523 if (tcp_get_flags(th) & TH_FIN) 3524 tlen++; 3525 tcp_respond(tp, mtod(m, void *), th, m, th->th_seq+tlen, 3526 (tcp_seq)0, TH_RST|TH_ACK); 3527 } 3528 return; 3529 drop: 3530 m_freem(m); 3531 } 3532 3533 /* 3534 * Parse TCP options and place in tcpopt. 3535 */ 3536 void 3537 tcp_dooptions(struct tcpopt *to, u_char *cp, int cnt, int flags) 3538 { 3539 int opt, optlen; 3540 3541 to->to_flags = 0; 3542 for (; cnt > 0; cnt -= optlen, cp += optlen) { 3543 opt = cp[0]; 3544 if (opt == TCPOPT_EOL) 3545 break; 3546 if (opt == TCPOPT_NOP) 3547 optlen = 1; 3548 else { 3549 if (cnt < 2) 3550 break; 3551 optlen = cp[1]; 3552 if (optlen < 2 || optlen > cnt) 3553 break; 3554 } 3555 switch (opt) { 3556 case TCPOPT_MAXSEG: 3557 if (optlen != TCPOLEN_MAXSEG) 3558 continue; 3559 if (!(flags & TO_SYN)) 3560 continue; 3561 to->to_flags |= TOF_MSS; 3562 bcopy((char *)cp + 2, 3563 (char *)&to->to_mss, sizeof(to->to_mss)); 3564 to->to_mss = ntohs(to->to_mss); 3565 break; 3566 case TCPOPT_WINDOW: 3567 if (optlen != TCPOLEN_WINDOW) 3568 continue; 3569 if (!(flags & TO_SYN)) 3570 continue; 3571 to->to_flags |= TOF_SCALE; 3572 to->to_wscale = min(cp[2], TCP_MAX_WINSHIFT); 3573 break; 3574 case TCPOPT_TIMESTAMP: 3575 if (optlen != TCPOLEN_TIMESTAMP) 3576 continue; 3577 to->to_flags |= TOF_TS; 3578 bcopy((char *)cp + 2, 3579 (char *)&to->to_tsval, sizeof(to->to_tsval)); 3580 to->to_tsval = ntohl(to->to_tsval); 3581 bcopy((char *)cp + 6, 3582 (char *)&to->to_tsecr, sizeof(to->to_tsecr)); 3583 to->to_tsecr = ntohl(to->to_tsecr); 3584 break; 3585 case TCPOPT_SIGNATURE: 3586 /* 3587 * In order to reply to a host which has set the 3588 * TCP_SIGNATURE option in its initial SYN, we have 3589 * to record the fact that the option was observed 3590 * here for the syncache code to perform the correct 3591 * response. 3592 */ 3593 if (optlen != TCPOLEN_SIGNATURE) 3594 continue; 3595 to->to_flags |= TOF_SIGNATURE; 3596 to->to_signature = cp + 2; 3597 break; 3598 case TCPOPT_SACK_PERMITTED: 3599 if (optlen != TCPOLEN_SACK_PERMITTED) 3600 continue; 3601 if (!(flags & TO_SYN)) 3602 continue; 3603 if (!V_tcp_do_sack) 3604 continue; 3605 to->to_flags |= TOF_SACKPERM; 3606 break; 3607 case TCPOPT_SACK: 3608 if (optlen <= 2 || (optlen - 2) % TCPOLEN_SACK != 0) 3609 continue; 3610 if (flags & TO_SYN) 3611 continue; 3612 to->to_flags |= TOF_SACK; 3613 to->to_nsacks = (optlen - 2) / TCPOLEN_SACK; 3614 to->to_sacks = cp + 2; 3615 TCPSTAT_INC(tcps_sack_rcv_blocks); 3616 break; 3617 case TCPOPT_FAST_OPEN: 3618 /* 3619 * Cookie length validation is performed by the 3620 * server side cookie checking code or the client 3621 * side cookie cache update code. 3622 */ 3623 if (!(flags & TO_SYN)) 3624 continue; 3625 if (!V_tcp_fastopen_client_enable && 3626 !V_tcp_fastopen_server_enable) 3627 continue; 3628 to->to_flags |= TOF_FASTOPEN; 3629 to->to_tfo_len = optlen - 2; 3630 to->to_tfo_cookie = to->to_tfo_len ? cp + 2 : NULL; 3631 break; 3632 default: 3633 continue; 3634 } 3635 } 3636 } 3637 3638 /* 3639 * Pull out of band byte out of a segment so 3640 * it doesn't appear in the user's data queue. 3641 * It is still reflected in the segment length for 3642 * sequencing purposes. 3643 */ 3644 void 3645 tcp_pulloutofband(struct socket *so, struct tcphdr *th, struct mbuf *m, 3646 int off) 3647 { 3648 int cnt = off + th->th_urp - 1; 3649 3650 while (cnt >= 0) { 3651 if (m->m_len > cnt) { 3652 char *cp = mtod(m, caddr_t) + cnt; 3653 struct tcpcb *tp = sototcpcb(so); 3654 3655 INP_WLOCK_ASSERT(tptoinpcb(tp)); 3656 3657 tp->t_iobc = *cp; 3658 tp->t_oobflags |= TCPOOB_HAVEDATA; 3659 bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); 3660 m->m_len--; 3661 if (m->m_flags & M_PKTHDR) 3662 m->m_pkthdr.len--; 3663 return; 3664 } 3665 cnt -= m->m_len; 3666 m = m->m_next; 3667 if (m == NULL) 3668 break; 3669 } 3670 panic("tcp_pulloutofband"); 3671 } 3672 3673 /* 3674 * Collect new round-trip time estimate 3675 * and update averages and current timeout. 3676 */ 3677 void 3678 tcp_xmit_timer(struct tcpcb *tp, int rtt) 3679 { 3680 int delta; 3681 3682 INP_WLOCK_ASSERT(tptoinpcb(tp)); 3683 3684 TCPSTAT_INC(tcps_rttupdated); 3685 if (tp->t_rttupdated < UCHAR_MAX) 3686 tp->t_rttupdated++; 3687 #ifdef STATS 3688 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_RTT, 3689 imax(0, rtt * 1000 / hz)); 3690 #endif 3691 if ((tp->t_srtt != 0) && (tp->t_rxtshift <= TCP_RTT_INVALIDATE)) { 3692 /* 3693 * srtt is stored as fixed point with 5 bits after the 3694 * binary point (i.e., scaled by 8). The following magic 3695 * is equivalent to the smoothing algorithm in rfc793 with 3696 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed 3697 * point). Adjust rtt to origin 0. 3698 */ 3699 delta = ((rtt - 1) << TCP_DELTA_SHIFT) 3700 - (tp->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT)); 3701 3702 if ((tp->t_srtt += delta) <= 0) 3703 tp->t_srtt = 1; 3704 3705 /* 3706 * We accumulate a smoothed rtt variance (actually, a 3707 * smoothed mean difference), then set the retransmit 3708 * timer to smoothed rtt + 4 times the smoothed variance. 3709 * rttvar is stored as fixed point with 4 bits after the 3710 * binary point (scaled by 16). The following is 3711 * equivalent to rfc793 smoothing with an alpha of .75 3712 * (rttvar = rttvar*3/4 + |delta| / 4). This replaces 3713 * rfc793's wired-in beta. 3714 */ 3715 if (delta < 0) 3716 delta = -delta; 3717 delta -= tp->t_rttvar >> (TCP_RTTVAR_SHIFT - TCP_DELTA_SHIFT); 3718 if ((tp->t_rttvar += delta) <= 0) 3719 tp->t_rttvar = 1; 3720 } else { 3721 /* 3722 * No rtt measurement yet - use the unsmoothed rtt. 3723 * Set the variance to half the rtt (so our first 3724 * retransmit happens at 3*rtt). 3725 */ 3726 tp->t_srtt = rtt << TCP_RTT_SHIFT; 3727 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1); 3728 } 3729 tp->t_rtttime = 0; 3730 tp->t_rxtshift = 0; 3731 3732 /* 3733 * the retransmit should happen at rtt + 4 * rttvar. 3734 * Because of the way we do the smoothing, srtt and rttvar 3735 * will each average +1/2 tick of bias. When we compute 3736 * the retransmit timer, we want 1/2 tick of rounding and 3737 * 1 extra tick because of +-1/2 tick uncertainty in the 3738 * firing of the timer. The bias will give us exactly the 3739 * 1.5 tick we need. But, because the bias is 3740 * statistical, we have to test that we don't drop below 3741 * the minimum feasible timer (which is 2 ticks). 3742 */ 3743 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), 3744 max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX); 3745 3746 /* 3747 * We received an ack for a packet that wasn't retransmitted; 3748 * it is probably safe to discard any error indications we've 3749 * received recently. This isn't quite right, but close enough 3750 * for now (a route might have failed after we sent a segment, 3751 * and the return path might not be symmetrical). 3752 */ 3753 tp->t_softerror = 0; 3754 } 3755 3756 /* 3757 * Determine a reasonable value for maxseg size. 3758 * If the route is known, check route for mtu. 3759 * If none, use an mss that can be handled on the outgoing interface 3760 * without forcing IP to fragment. If no route is found, route has no mtu, 3761 * or the destination isn't local, use a default, hopefully conservative 3762 * size (usually 512 or the default IP max size, but no more than the mtu 3763 * of the interface), as we can't discover anything about intervening 3764 * gateways or networks. We also initialize the congestion/slow start 3765 * window to be a single segment if the destination isn't local. 3766 * While looking at the routing entry, we also initialize other path-dependent 3767 * parameters from pre-set or cached values in the routing entry. 3768 * 3769 * NOTE that resulting t_maxseg doesn't include space for TCP options or 3770 * IP options, e.g. IPSEC data, since length of this data may vary, and 3771 * thus it is calculated for every segment separately in tcp_output(). 3772 * 3773 * NOTE that this routine is only called when we process an incoming 3774 * segment, or an ICMP need fragmentation datagram. Outgoing SYN/ACK MSS 3775 * settings are handled in tcp_mssopt(). 3776 */ 3777 void 3778 tcp_mss_update(struct tcpcb *tp, int offer, int mtuoffer, 3779 struct hc_metrics_lite *metricptr, struct tcp_ifcap *cap) 3780 { 3781 int mss = 0; 3782 uint32_t maxmtu = 0; 3783 struct inpcb *inp = tptoinpcb(tp); 3784 struct hc_metrics_lite metrics; 3785 #ifdef INET6 3786 int isipv6 = ((inp->inp_vflag & INP_IPV6) != 0) ? 1 : 0; 3787 size_t min_protoh = isipv6 ? 3788 sizeof (struct ip6_hdr) + sizeof (struct tcphdr) : 3789 sizeof (struct tcpiphdr); 3790 #else 3791 size_t min_protoh = sizeof(struct tcpiphdr); 3792 #endif 3793 3794 INP_WLOCK_ASSERT(inp); 3795 3796 if (tp->t_port) 3797 min_protoh += V_tcp_udp_tunneling_overhead; 3798 if (mtuoffer != -1) { 3799 KASSERT(offer == -1, ("%s: conflict", __func__)); 3800 offer = mtuoffer - min_protoh; 3801 } 3802 3803 /* Initialize. */ 3804 #ifdef INET6 3805 if (isipv6) { 3806 maxmtu = tcp_maxmtu6(&inp->inp_inc, cap); 3807 tp->t_maxseg = V_tcp_v6mssdflt; 3808 } 3809 #endif 3810 #if defined(INET) && defined(INET6) 3811 else 3812 #endif 3813 #ifdef INET 3814 { 3815 maxmtu = tcp_maxmtu(&inp->inp_inc, cap); 3816 tp->t_maxseg = V_tcp_mssdflt; 3817 } 3818 #endif 3819 3820 /* 3821 * No route to sender, stay with default mss and return. 3822 */ 3823 if (maxmtu == 0) { 3824 /* 3825 * In case we return early we need to initialize metrics 3826 * to a defined state as tcp_hc_get() would do for us 3827 * if there was no cache hit. 3828 */ 3829 if (metricptr != NULL) 3830 bzero(metricptr, sizeof(struct hc_metrics_lite)); 3831 return; 3832 } 3833 3834 /* What have we got? */ 3835 switch (offer) { 3836 case 0: 3837 /* 3838 * Offer == 0 means that there was no MSS on the SYN 3839 * segment, in this case we use tcp_mssdflt as 3840 * already assigned to t_maxseg above. 3841 */ 3842 offer = tp->t_maxseg; 3843 break; 3844 3845 case -1: 3846 /* 3847 * Offer == -1 means that we didn't receive SYN yet. 3848 */ 3849 /* FALLTHROUGH */ 3850 3851 default: 3852 /* 3853 * Prevent DoS attack with too small MSS. Round up 3854 * to at least minmss. 3855 */ 3856 offer = max(offer, V_tcp_minmss); 3857 } 3858 3859 /* 3860 * rmx information is now retrieved from tcp_hostcache. 3861 */ 3862 tcp_hc_get(&inp->inp_inc, &metrics); 3863 if (metricptr != NULL) 3864 bcopy(&metrics, metricptr, sizeof(struct hc_metrics_lite)); 3865 3866 /* 3867 * If there's a discovered mtu in tcp hostcache, use it. 3868 * Else, use the link mtu. 3869 */ 3870 if (metrics.rmx_mtu) 3871 mss = min(metrics.rmx_mtu, maxmtu) - min_protoh; 3872 else { 3873 #ifdef INET6 3874 if (isipv6) { 3875 mss = maxmtu - min_protoh; 3876 if (!V_path_mtu_discovery && 3877 !in6_localaddr(&inp->in6p_faddr)) 3878 mss = min(mss, V_tcp_v6mssdflt); 3879 } 3880 #endif 3881 #if defined(INET) && defined(INET6) 3882 else 3883 #endif 3884 #ifdef INET 3885 { 3886 mss = maxmtu - min_protoh; 3887 if (!V_path_mtu_discovery && 3888 !in_localaddr(inp->inp_faddr)) 3889 mss = min(mss, V_tcp_mssdflt); 3890 } 3891 #endif 3892 /* 3893 * XXX - The above conditional (mss = maxmtu - min_protoh) 3894 * probably violates the TCP spec. 3895 * The problem is that, since we don't know the 3896 * other end's MSS, we are supposed to use a conservative 3897 * default. But, if we do that, then MTU discovery will 3898 * never actually take place, because the conservative 3899 * default is much less than the MTUs typically seen 3900 * on the Internet today. For the moment, we'll sweep 3901 * this under the carpet. 3902 * 3903 * The conservative default might not actually be a problem 3904 * if the only case this occurs is when sending an initial 3905 * SYN with options and data to a host we've never talked 3906 * to before. Then, they will reply with an MSS value which 3907 * will get recorded and the new parameters should get 3908 * recomputed. For Further Study. 3909 */ 3910 } 3911 mss = min(mss, offer); 3912 3913 /* 3914 * Sanity check: make sure that maxseg will be large 3915 * enough to allow some data on segments even if the 3916 * all the option space is used (40bytes). Otherwise 3917 * funny things may happen in tcp_output. 3918 * 3919 * XXXGL: shouldn't we reserve space for IP/IPv6 options? 3920 */ 3921 mss = max(mss, 64); 3922 3923 tp->t_maxseg = mss; 3924 if (tp->t_maxseg < V_tcp_mssdflt) { 3925 /* 3926 * The MSS is so small we should not process incoming 3927 * SACK's since we are subject to attack in such a 3928 * case. 3929 */ 3930 tp->t_flags2 |= TF2_PROC_SACK_PROHIBIT; 3931 } else { 3932 tp->t_flags2 &= ~TF2_PROC_SACK_PROHIBIT; 3933 } 3934 3935 } 3936 3937 void 3938 tcp_mss(struct tcpcb *tp, int offer) 3939 { 3940 int mss; 3941 uint32_t bufsize; 3942 struct inpcb *inp = tptoinpcb(tp); 3943 struct socket *so; 3944 struct hc_metrics_lite metrics; 3945 struct tcp_ifcap cap; 3946 3947 KASSERT(tp != NULL, ("%s: tp == NULL", __func__)); 3948 3949 bzero(&cap, sizeof(cap)); 3950 tcp_mss_update(tp, offer, -1, &metrics, &cap); 3951 3952 mss = tp->t_maxseg; 3953 3954 /* 3955 * If there's a pipesize, change the socket buffer to that size, 3956 * don't change if sb_hiwat is different than default (then it 3957 * has been changed on purpose with setsockopt). 3958 * Make the socket buffers an integral number of mss units; 3959 * if the mss is larger than the socket buffer, decrease the mss. 3960 */ 3961 so = inp->inp_socket; 3962 SOCKBUF_LOCK(&so->so_snd); 3963 if ((so->so_snd.sb_hiwat == V_tcp_sendspace) && metrics.rmx_sendpipe) 3964 bufsize = metrics.rmx_sendpipe; 3965 else 3966 bufsize = so->so_snd.sb_hiwat; 3967 if (bufsize < mss) 3968 mss = bufsize; 3969 else { 3970 bufsize = roundup(bufsize, mss); 3971 if (bufsize > sb_max) 3972 bufsize = sb_max; 3973 if (bufsize > so->so_snd.sb_hiwat) 3974 (void)sbreserve_locked(so, SO_SND, bufsize, NULL); 3975 } 3976 SOCKBUF_UNLOCK(&so->so_snd); 3977 /* 3978 * Sanity check: make sure that maxseg will be large 3979 * enough to allow some data on segments even if the 3980 * all the option space is used (40bytes). Otherwise 3981 * funny things may happen in tcp_output. 3982 * 3983 * XXXGL: shouldn't we reserve space for IP/IPv6 options? 3984 */ 3985 tp->t_maxseg = max(mss, 64); 3986 if (tp->t_maxseg < V_tcp_mssdflt) { 3987 /* 3988 * The MSS is so small we should not process incoming 3989 * SACK's since we are subject to attack in such a 3990 * case. 3991 */ 3992 tp->t_flags2 |= TF2_PROC_SACK_PROHIBIT; 3993 } else { 3994 tp->t_flags2 &= ~TF2_PROC_SACK_PROHIBIT; 3995 } 3996 3997 SOCKBUF_LOCK(&so->so_rcv); 3998 if ((so->so_rcv.sb_hiwat == V_tcp_recvspace) && metrics.rmx_recvpipe) 3999 bufsize = metrics.rmx_recvpipe; 4000 else 4001 bufsize = so->so_rcv.sb_hiwat; 4002 if (bufsize > mss) { 4003 bufsize = roundup(bufsize, mss); 4004 if (bufsize > sb_max) 4005 bufsize = sb_max; 4006 if (bufsize > so->so_rcv.sb_hiwat) 4007 (void)sbreserve_locked(so, SO_RCV, bufsize, NULL); 4008 } 4009 SOCKBUF_UNLOCK(&so->so_rcv); 4010 4011 /* Check the interface for TSO capabilities. */ 4012 if (cap.ifcap & CSUM_TSO) { 4013 tp->t_flags |= TF_TSO; 4014 tp->t_tsomax = cap.tsomax; 4015 tp->t_tsomaxsegcount = cap.tsomaxsegcount; 4016 tp->t_tsomaxsegsize = cap.tsomaxsegsize; 4017 if (cap.ipsec_tso) 4018 tp->t_flags2 |= TF2_IPSEC_TSO; 4019 } 4020 } 4021 4022 /* 4023 * Determine the MSS option to send on an outgoing SYN. 4024 */ 4025 int 4026 tcp_mssopt(struct in_conninfo *inc) 4027 { 4028 int mss = 0; 4029 uint32_t thcmtu = 0; 4030 uint32_t maxmtu = 0; 4031 size_t min_protoh; 4032 4033 KASSERT(inc != NULL, ("tcp_mssopt with NULL in_conninfo pointer")); 4034 4035 #ifdef INET6 4036 if (inc->inc_flags & INC_ISIPV6) { 4037 mss = V_tcp_v6mssdflt; 4038 maxmtu = tcp_maxmtu6(inc, NULL); 4039 min_protoh = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 4040 } 4041 #endif 4042 #if defined(INET) && defined(INET6) 4043 else 4044 #endif 4045 #ifdef INET 4046 { 4047 mss = V_tcp_mssdflt; 4048 maxmtu = tcp_maxmtu(inc, NULL); 4049 min_protoh = sizeof(struct tcpiphdr); 4050 } 4051 #endif 4052 #if defined(INET6) || defined(INET) 4053 thcmtu = tcp_hc_getmtu(inc); /* IPv4 and IPv6 */ 4054 #endif 4055 4056 if (maxmtu && thcmtu) 4057 mss = min(maxmtu, thcmtu) - min_protoh; 4058 else if (maxmtu || thcmtu) 4059 mss = max(maxmtu, thcmtu) - min_protoh; 4060 4061 return (mss); 4062 } 4063 4064 void 4065 tcp_do_prr_ack(struct tcpcb *tp, struct tcphdr *th, struct tcpopt *to, 4066 sackstatus_t sack_changed, u_int *maxsegp) 4067 { 4068 int snd_cnt = 0, limit = 0, del_data = 0, pipe = 0; 4069 u_int maxseg; 4070 4071 INP_WLOCK_ASSERT(tptoinpcb(tp)); 4072 4073 if (*maxsegp == 0) { 4074 *maxsegp = tcp_maxseg(tp); 4075 } 4076 maxseg = *maxsegp; 4077 /* 4078 * Compute the amount of data that this ACK is indicating 4079 * (del_data) and an estimate of how many bytes are in the 4080 * network. 4081 */ 4082 if (tcp_is_sack_recovery(tp, to) || 4083 (IN_CONGRECOVERY(tp->t_flags) && 4084 !IN_FASTRECOVERY(tp->t_flags))) { 4085 del_data = tp->sackhint.delivered_data; 4086 if (V_tcp_do_newsack) 4087 pipe = tcp_compute_pipe(tp); 4088 else 4089 pipe = (tp->snd_nxt - tp->snd_fack) + 4090 tp->sackhint.sack_bytes_rexmit; 4091 } else { 4092 if (tp->sackhint.prr_delivered < (tcprexmtthresh * maxseg + 4093 tp->snd_recover - tp->snd_una)) { 4094 del_data = maxseg; 4095 } 4096 pipe = imax(0, tp->snd_max - tp->snd_una - 4097 imin(INT_MAX / 65536, tp->t_dupacks) * maxseg); 4098 } 4099 tp->sackhint.prr_delivered += del_data; 4100 /* 4101 * Proportional Rate Reduction 4102 */ 4103 if (pipe >= tp->snd_ssthresh) { 4104 if (tp->sackhint.recover_fs == 0) 4105 tp->sackhint.recover_fs = 4106 imax(1, tp->snd_nxt - tp->snd_una); 4107 snd_cnt = howmany((long)tp->sackhint.prr_delivered * 4108 tp->snd_ssthresh, tp->sackhint.recover_fs) - 4109 tp->sackhint.prr_out + maxseg - 1; 4110 } else { 4111 /* 4112 * PRR 6937bis heuristic: 4113 * - A partial ack without SACK block beneath snd_recover 4114 * indicates further loss. 4115 * - An SACK scoreboard update adding a new hole indicates 4116 * further loss, so be conservative and send at most one 4117 * segment. 4118 * - Prevent ACK splitting attacks, by being conservative 4119 * when no new data is acked. 4120 */ 4121 if ((sack_changed == SACK_NEWLOSS) || (del_data == 0)) { 4122 limit = tp->sackhint.prr_delivered - 4123 tp->sackhint.prr_out; 4124 } else { 4125 limit = imax(tp->sackhint.prr_delivered - 4126 tp->sackhint.prr_out, del_data) + 4127 maxseg; 4128 } 4129 snd_cnt = imin((tp->snd_ssthresh - pipe), limit); 4130 } 4131 snd_cnt = imax(snd_cnt, 0) / maxseg; 4132 /* 4133 * Send snd_cnt new data into the network in response to this ack. 4134 * If there is going to be a SACK retransmission, adjust snd_cwnd 4135 * accordingly. 4136 */ 4137 if (IN_FASTRECOVERY(tp->t_flags)) { 4138 if (tcp_is_sack_recovery(tp, to)) { 4139 tp->snd_cwnd = tp->snd_nxt - tp->snd_recover + 4140 tp->sackhint.sack_bytes_rexmit + 4141 (snd_cnt * maxseg); 4142 } else { 4143 tp->snd_cwnd = (tp->snd_max - tp->snd_una) + 4144 (snd_cnt * maxseg); 4145 } 4146 } else if (IN_CONGRECOVERY(tp->t_flags)) { 4147 tp->snd_cwnd = pipe - del_data + (snd_cnt * maxseg); 4148 } 4149 tp->snd_cwnd = imax(maxseg, tp->snd_cwnd); 4150 } 4151 4152 /* 4153 * On a partial ack arrives, force the retransmission of the 4154 * next unacknowledged segment. Do not clear tp->t_dupacks. 4155 * By setting snd_nxt to ti_ack, this forces retransmission timer to 4156 * be started again. 4157 */ 4158 void 4159 tcp_newreno_partial_ack(struct tcpcb *tp, struct tcphdr *th) 4160 { 4161 tcp_seq onxt = tp->snd_nxt; 4162 uint32_t ocwnd = tp->snd_cwnd; 4163 u_int maxseg = tcp_maxseg(tp); 4164 4165 INP_WLOCK_ASSERT(tptoinpcb(tp)); 4166 4167 tcp_timer_activate(tp, TT_REXMT, 0); 4168 tp->t_rtttime = 0; 4169 tp->snd_nxt = th->th_ack; 4170 /* 4171 * Set snd_cwnd to one segment beyond acknowledged offset. 4172 * (tp->snd_una has not yet been updated when this function is called.) 4173 */ 4174 tp->snd_cwnd = maxseg + BYTES_THIS_ACK(tp, th); 4175 tp->t_flags |= TF_ACKNOW; 4176 (void) tcp_output(tp); 4177 tp->snd_cwnd = ocwnd; 4178 if (SEQ_GT(onxt, tp->snd_nxt)) 4179 tp->snd_nxt = onxt; 4180 /* 4181 * Partial window deflation. Relies on fact that tp->snd_una 4182 * not updated yet. 4183 */ 4184 if (tp->snd_cwnd > BYTES_THIS_ACK(tp, th)) 4185 tp->snd_cwnd -= BYTES_THIS_ACK(tp, th); 4186 else 4187 tp->snd_cwnd = 0; 4188 tp->snd_cwnd += maxseg; 4189 } 4190 4191 int 4192 tcp_compute_pipe(struct tcpcb *tp) 4193 { 4194 if (tp->t_fb->tfb_compute_pipe == NULL) { 4195 return (tp->snd_max - tp->snd_una + 4196 tp->sackhint.sack_bytes_rexmit - 4197 tp->sackhint.sacked_bytes - 4198 tp->sackhint.lost_bytes); 4199 } else { 4200 return((*tp->t_fb->tfb_compute_pipe)(tp)); 4201 } 4202 } 4203 4204 uint32_t 4205 tcp_compute_initwnd(uint32_t maxseg) 4206 { 4207 /* 4208 * Calculate the Initial Window, also used as Restart Window 4209 * 4210 * RFC5681 Section 3.1 specifies the default conservative values. 4211 * RFC3390 specifies slightly more aggressive values. 4212 * RFC6928 increases it to ten segments. 4213 * Support for user specified value for initial flight size. 4214 */ 4215 if (V_tcp_initcwnd_segments) 4216 return min(V_tcp_initcwnd_segments * maxseg, 4217 max(2 * maxseg, V_tcp_initcwnd_segments * 1460)); 4218 else if (V_tcp_do_rfc3390) 4219 return min(4 * maxseg, max(2 * maxseg, 4380)); 4220 else { 4221 /* Per RFC5681 Section 3.1 */ 4222 if (maxseg > 2190) 4223 return (2 * maxseg); 4224 else if (maxseg > 1095) 4225 return (3 * maxseg); 4226 else 4227 return (4 * maxseg); 4228 } 4229 } 4230