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 #include <netinet/tcp_syncache.h> 116 #ifdef TCP_OFFLOAD 117 #include <netinet/tcp_offload.h> 118 #endif 119 #include <netinet/tcp_ecn.h> 120 #include <netinet/udp.h> 121 122 #include <netipsec/ipsec_support.h> 123 124 #include <machine/in_cksum.h> 125 126 #include <security/mac/mac_framework.h> 127 128 const int tcprexmtthresh = 3; 129 130 VNET_DEFINE(int, tcp_log_in_vain) = 0; 131 SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_in_vain, CTLFLAG_VNET | CTLFLAG_RW, 132 &VNET_NAME(tcp_log_in_vain), 0, 133 "Log all incoming TCP segments to closed ports"); 134 135 VNET_DEFINE(int, tcp_bind_all_fibs) = 1; 136 SYSCTL_INT(_net_inet_tcp, OID_AUTO, bind_all_fibs, CTLFLAG_VNET | CTLFLAG_RDTUN, 137 &VNET_NAME(tcp_bind_all_fibs), 0, 138 "Bound sockets receive traffic from all FIBs"); 139 140 VNET_DEFINE(int, blackhole) = 0; 141 #define V_blackhole VNET(blackhole) 142 SYSCTL_INT(_net_inet_tcp, OID_AUTO, blackhole, CTLFLAG_VNET | CTLFLAG_RW, 143 &VNET_NAME(blackhole), 0, 144 "Do not send RST on segments to closed ports"); 145 146 VNET_DEFINE(bool, blackhole_local) = false; 147 #define V_blackhole_local VNET(blackhole_local) 148 SYSCTL_BOOL(_net_inet_tcp, OID_AUTO, blackhole_local, CTLFLAG_VNET | 149 CTLFLAG_RW, &VNET_NAME(blackhole_local), false, 150 "Enforce net.inet.tcp.blackhole for locally originated packets"); 151 152 VNET_DEFINE(int, tcp_delack_enabled) = 1; 153 SYSCTL_INT(_net_inet_tcp, OID_AUTO, delayed_ack, CTLFLAG_VNET | CTLFLAG_RW, 154 &VNET_NAME(tcp_delack_enabled), 0, 155 "Delay ACK to try and piggyback it onto a data packet"); 156 157 VNET_DEFINE(int, drop_synfin) = 0; 158 SYSCTL_INT(_net_inet_tcp, OID_AUTO, drop_synfin, CTLFLAG_VNET | CTLFLAG_RW, 159 &VNET_NAME(drop_synfin), 0, 160 "Drop TCP packets with SYN+FIN set"); 161 162 VNET_DEFINE(int, tcp_do_prr) = 1; 163 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_prr, CTLFLAG_VNET | CTLFLAG_RW, 164 &VNET_NAME(tcp_do_prr), 1, 165 "Enable Proportional Rate Reduction per RFC 6937"); 166 167 VNET_DEFINE(int, tcp_do_newcwv) = 0; 168 SYSCTL_INT(_net_inet_tcp, OID_AUTO, newcwv, CTLFLAG_VNET | CTLFLAG_RW, 169 &VNET_NAME(tcp_do_newcwv), 0, 170 "Enable New Congestion Window Validation per RFC7661"); 171 172 VNET_DEFINE(int, tcp_do_rfc3042) = 1; 173 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3042, CTLFLAG_VNET | CTLFLAG_RW, 174 &VNET_NAME(tcp_do_rfc3042), 0, 175 "Enable RFC 3042 (Limited Transmit)"); 176 177 VNET_DEFINE(int, tcp_do_rfc3390) = 1; 178 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3390, CTLFLAG_VNET | CTLFLAG_RW, 179 &VNET_NAME(tcp_do_rfc3390), 0, 180 "Enable RFC 3390 (Increasing TCP's Initial Congestion Window)"); 181 182 VNET_DEFINE(int, tcp_initcwnd_segments) = 10; 183 SYSCTL_INT(_net_inet_tcp, OID_AUTO, initcwnd_segments, 184 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(tcp_initcwnd_segments), 0, 185 "Slow-start flight size (initial congestion window) in number of segments"); 186 187 VNET_DEFINE(int, tcp_do_rfc3465) = 1; 188 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3465, CTLFLAG_VNET | CTLFLAG_RW, 189 &VNET_NAME(tcp_do_rfc3465), 0, 190 "Enable RFC 3465 (Appropriate Byte Counting)"); 191 192 VNET_DEFINE(int, tcp_abc_l_var) = 2; 193 SYSCTL_INT(_net_inet_tcp, OID_AUTO, abc_l_var, CTLFLAG_VNET | CTLFLAG_RW, 194 &VNET_NAME(tcp_abc_l_var), 2, 195 "Cap the max cwnd increment during slow-start to this number of segments"); 196 197 VNET_DEFINE(int, tcp_insecure_syn) = 0; 198 SYSCTL_INT(_net_inet_tcp, OID_AUTO, insecure_syn, CTLFLAG_VNET | CTLFLAG_RW, 199 &VNET_NAME(tcp_insecure_syn), 0, 200 "Follow RFC793 instead of RFC5961 criteria for accepting SYN packets"); 201 202 VNET_DEFINE(int, tcp_insecure_rst) = 0; 203 SYSCTL_INT(_net_inet_tcp, OID_AUTO, insecure_rst, CTLFLAG_VNET | CTLFLAG_RW, 204 &VNET_NAME(tcp_insecure_rst), 0, 205 "Follow RFC793 instead of RFC5961 criteria for accepting RST packets"); 206 207 VNET_DEFINE(int, tcp_insecure_ack) = 0; 208 SYSCTL_INT(_net_inet_tcp, OID_AUTO, insecure_ack, CTLFLAG_VNET | CTLFLAG_RW, 209 &VNET_NAME(tcp_insecure_ack), 0, 210 "Follow RFC793 criteria for validating SEG.ACK"); 211 212 VNET_DEFINE(int, tcp_recvspace) = 1024*64; 213 #define V_tcp_recvspace VNET(tcp_recvspace) 214 SYSCTL_INT(_net_inet_tcp, TCPCTL_RECVSPACE, recvspace, CTLFLAG_VNET | CTLFLAG_RW, 215 &VNET_NAME(tcp_recvspace), 0, "Initial receive socket buffer size"); 216 217 VNET_DEFINE(int, tcp_do_autorcvbuf) = 1; 218 SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_auto, CTLFLAG_VNET | CTLFLAG_RW, 219 &VNET_NAME(tcp_do_autorcvbuf), 0, 220 "Enable automatic receive buffer sizing"); 221 222 VNET_DEFINE(int, tcp_autorcvbuf_max) = 2*1024*1024; 223 SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_max, CTLFLAG_VNET | CTLFLAG_RW, 224 &VNET_NAME(tcp_autorcvbuf_max), 0, 225 "Max size of automatic receive buffer"); 226 227 VNET_DEFINE(struct inpcbinfo, tcbinfo); 228 229 /* 230 * TCP statistics are stored in an array of counter(9)s, which size matches 231 * size of struct tcpstat. TCP running connection count is a regular array. 232 */ 233 VNET_PCPUSTAT_DEFINE(struct tcpstat, tcpstat); 234 SYSCTL_VNET_PCPUSTAT(_net_inet_tcp, TCPCTL_STATS, stats, struct tcpstat, 235 tcpstat, "TCP statistics (struct tcpstat, netinet/tcp_var.h)"); 236 VNET_DEFINE(counter_u64_t, tcps_states[TCP_NSTATES]); 237 SYSCTL_COUNTER_U64_ARRAY(_net_inet_tcp, TCPCTL_STATES, states, CTLFLAG_RD | 238 CTLFLAG_VNET, &VNET_NAME(tcps_states)[0], TCP_NSTATES, 239 "TCP connection counts by TCP state"); 240 241 /* 242 * Kernel module interface for updating tcpstat. The first argument is an index 243 * into tcpstat treated as an array. 244 */ 245 void 246 kmod_tcpstat_add(int statnum, int val) 247 { 248 249 counter_u64_add(VNET(tcpstat)[statnum], val); 250 } 251 252 /* 253 * Make sure that we only start a SACK loss recovery when 254 * receiving a duplicate ACK with a SACK block, and also 255 * complete SACK loss recovery in case the other end 256 * reneges. 257 */ 258 static bool inline 259 tcp_is_sack_recovery(struct tcpcb *tp, struct tcpopt *to) 260 { 261 return ((tp->t_flags & TF_SACK_PERMIT) && 262 ((to->to_flags & TOF_SACK) || 263 (!TAILQ_EMPTY(&tp->snd_holes)))); 264 } 265 266 #ifdef TCP_HHOOK 267 /* 268 * Wrapper for the TCP established input helper hook. 269 */ 270 void 271 hhook_run_tcp_est_in(struct tcpcb *tp, struct tcphdr *th, struct tcpopt *to) 272 { 273 struct tcp_hhook_data hhook_data; 274 275 if (V_tcp_hhh[HHOOK_TCP_EST_IN]->hhh_nhooks > 0) { 276 hhook_data.tp = tp; 277 hhook_data.th = th; 278 hhook_data.to = to; 279 280 hhook_run_hooks(V_tcp_hhh[HHOOK_TCP_EST_IN], &hhook_data, 281 &tp->t_osd); 282 } 283 } 284 #endif 285 286 /* 287 * CC wrapper hook functions 288 */ 289 void 290 cc_ack_received(struct tcpcb *tp, struct tcphdr *th, uint16_t nsegs, 291 uint16_t type) 292 { 293 #ifdef STATS 294 int32_t gput; 295 #endif 296 297 INP_WLOCK_ASSERT(tptoinpcb(tp)); 298 299 tp->t_ccv.nsegs = nsegs; 300 tp->t_ccv.bytes_this_ack = BYTES_THIS_ACK(tp, th); 301 if ((!V_tcp_do_newcwv && (tp->snd_cwnd <= tp->snd_wnd)) || 302 (V_tcp_do_newcwv && (tp->snd_cwnd <= tp->snd_wnd) && 303 (tp->snd_cwnd < (tcp_compute_pipe(tp) * 2)))) 304 tp->t_ccv.flags |= CCF_CWND_LIMITED; 305 else 306 tp->t_ccv.flags &= ~CCF_CWND_LIMITED; 307 308 if (type == CC_ACK) { 309 #ifdef STATS 310 stats_voi_update_abs_s32(tp->t_stats, VOI_TCP_CALCFRWINDIFF, 311 ((int32_t)tp->snd_cwnd) - tp->snd_wnd); 312 if (!IN_RECOVERY(tp->t_flags)) 313 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_ACKLEN, 314 tp->t_ccv.bytes_this_ack / (tcp_maxseg(tp) * nsegs)); 315 if ((tp->t_flags & TF_GPUTINPROG) && 316 SEQ_GEQ(th->th_ack, tp->gput_ack)) { 317 /* 318 * Compute goodput in bits per millisecond. 319 */ 320 gput = (((int64_t)SEQ_SUB(th->th_ack, tp->gput_seq)) << 3) / 321 max(1, tcp_ts_getticks() - tp->gput_ts); 322 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_GPUT, 323 gput); 324 /* 325 * XXXLAS: This is a temporary hack, and should be 326 * chained off VOI_TCP_GPUT when stats(9) grows an API 327 * to deal with chained VOIs. 328 */ 329 if (tp->t_stats_gput_prev > 0) 330 stats_voi_update_abs_s32(tp->t_stats, 331 VOI_TCP_GPUT_ND, 332 ((gput - tp->t_stats_gput_prev) * 100) / 333 tp->t_stats_gput_prev); 334 tp->t_flags &= ~TF_GPUTINPROG; 335 tp->t_stats_gput_prev = gput; 336 } 337 #endif /* STATS */ 338 if (tp->snd_cwnd > tp->snd_ssthresh) { 339 tp->t_bytes_acked += tp->t_ccv.bytes_this_ack; 340 if (tp->t_bytes_acked >= tp->snd_cwnd) { 341 tp->t_bytes_acked -= tp->snd_cwnd; 342 tp->t_ccv.flags |= CCF_ABC_SENTAWND; 343 } 344 } else { 345 tp->t_ccv.flags &= ~CCF_ABC_SENTAWND; 346 tp->t_bytes_acked = 0; 347 } 348 } 349 350 if (CC_ALGO(tp)->ack_received != NULL) { 351 /* XXXLAS: Find a way to live without this */ 352 tp->t_ccv.curack = th->th_ack; 353 CC_ALGO(tp)->ack_received(&tp->t_ccv, type); 354 } 355 #ifdef STATS 356 stats_voi_update_abs_ulong(tp->t_stats, VOI_TCP_LCWIN, tp->snd_cwnd); 357 #endif 358 } 359 360 void 361 cc_conn_init(struct tcpcb *tp) 362 { 363 struct hc_metrics_lite metrics; 364 struct inpcb *inp = tptoinpcb(tp); 365 u_int maxseg; 366 int rtt; 367 368 INP_WLOCK_ASSERT(inp); 369 370 tcp_hc_get(&inp->inp_inc, &metrics); 371 maxseg = tcp_maxseg(tp); 372 373 if (tp->t_srtt == 0 && (rtt = metrics.hc_rtt)) { 374 tp->t_srtt = rtt; 375 TCPSTAT_INC(tcps_usedrtt); 376 if (metrics.hc_rttvar) { 377 tp->t_rttvar = metrics.hc_rttvar; 378 TCPSTAT_INC(tcps_usedrttvar); 379 } else { 380 /* default variation is +- 1 rtt */ 381 tp->t_rttvar = 382 tp->t_srtt * TCP_RTTVAR_SCALE / TCP_RTT_SCALE; 383 } 384 TCPT_RANGESET(tp->t_rxtcur, 385 ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1, 386 tp->t_rttmin, tcp_rexmit_max); 387 } 388 if (metrics.hc_ssthresh) { 389 /* 390 * There's some sort of gateway or interface 391 * buffer limit on the path. Use this to set 392 * the slow start threshold, but set the 393 * threshold to no less than 2*mss. 394 */ 395 tp->snd_ssthresh = max(2 * maxseg, metrics.hc_ssthresh); 396 TCPSTAT_INC(tcps_usedssthresh); 397 } 398 399 /* 400 * Set the initial slow-start flight size. 401 * 402 * If a SYN or SYN/ACK was lost and retransmitted, we have to 403 * reduce the initial CWND to one segment as congestion is likely 404 * requiring us to be cautious. 405 */ 406 if (tp->snd_cwnd == 1) 407 tp->snd_cwnd = maxseg; /* SYN(-ACK) lost */ 408 else 409 tp->snd_cwnd = tcp_compute_initwnd(maxseg); 410 411 if (CC_ALGO(tp)->conn_init != NULL) 412 CC_ALGO(tp)->conn_init(&tp->t_ccv); 413 } 414 415 void inline 416 cc_cong_signal(struct tcpcb *tp, struct tcphdr *th, uint32_t type) 417 { 418 INP_WLOCK_ASSERT(tptoinpcb(tp)); 419 420 #ifdef STATS 421 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_CSIG, type); 422 #endif 423 424 switch(type) { 425 case CC_NDUPACK: 426 if (!IN_FASTRECOVERY(tp->t_flags)) { 427 tp->snd_recover = tp->snd_max; 428 if (tp->t_flags2 & TF2_ECN_PERMIT) 429 tp->t_flags2 |= TF2_ECN_SND_CWR; 430 } 431 break; 432 case CC_ECN: 433 if (!IN_CONGRECOVERY(tp->t_flags) || 434 /* 435 * Allow ECN reaction on ACK to CWR, if 436 * that data segment was also CE marked. 437 */ 438 SEQ_GEQ(th->th_ack, tp->snd_recover)) { 439 EXIT_CONGRECOVERY(tp->t_flags); 440 TCPSTAT_INC(tcps_ecn_rcwnd); 441 tp->snd_recover = tp->snd_max + 1; 442 if (tp->t_flags2 & TF2_ECN_PERMIT) 443 tp->t_flags2 |= TF2_ECN_SND_CWR; 444 } 445 break; 446 case CC_RTO: 447 tp->t_dupacks = 0; 448 tp->t_bytes_acked = 0; 449 EXIT_RECOVERY(tp->t_flags); 450 if (tp->t_flags2 & TF2_ECN_PERMIT) 451 tp->t_flags2 |= TF2_ECN_SND_CWR; 452 break; 453 case CC_RTO_ERR: 454 TCPSTAT_INC(tcps_sndrexmitbad); 455 /* RTO was unnecessary, so reset everything. */ 456 tp->snd_cwnd = tp->snd_cwnd_prev; 457 tp->snd_ssthresh = tp->snd_ssthresh_prev; 458 tp->snd_recover = tp->snd_recover_prev; 459 if (tp->t_flags & TF_WASFRECOVERY) 460 ENTER_FASTRECOVERY(tp->t_flags); 461 if (tp->t_flags & TF_WASCRECOVERY) 462 ENTER_CONGRECOVERY(tp->t_flags); 463 tp->snd_nxt = tp->snd_max; 464 tp->t_flags &= ~TF_PREVVALID; 465 tp->t_rxtshift = 0; 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; 570 571 m = *mp; 572 if (m->m_len < *offp + sizeof(struct tcphdr)) { 573 m = m_pullup(m, *offp + sizeof(struct tcphdr)); 574 if (m == NULL) { 575 *mp = m; 576 TCPSTAT_INC(tcps_rcvshort); 577 return (IPPROTO_DONE); 578 } 579 } 580 581 *mp = m; 582 return (tcp_input_with_port(mp, offp, proto, port)); 583 } 584 585 int 586 tcp6_input(struct mbuf **mp, int *offp, int proto) 587 { 588 589 return(tcp6_input_with_port(mp, offp, proto, 0)); 590 } 591 #endif /* INET6 */ 592 593 int 594 tcp_input_with_port(struct mbuf **mp, int *offp, int proto, uint16_t port) 595 { 596 struct mbuf *m = *mp; 597 struct tcphdr *th = NULL; 598 struct ip *ip = NULL; 599 struct inpcb *inp = NULL; 600 struct tcpcb *tp = NULL; 601 struct socket *so = NULL; 602 u_char *optp = NULL; 603 int off0; 604 int optlen = 0; 605 #ifdef INET 606 int len; 607 uint8_t ipttl; 608 #endif 609 int tlen = 0, off; 610 int drop_hdrlen; 611 int thflags; 612 int lookupflag; 613 uint8_t iptos; 614 struct m_tag *fwd_tag = NULL; 615 #ifdef INET6 616 struct ip6_hdr *ip6 = NULL; 617 int isipv6; 618 #else 619 const void *ip6 = NULL; 620 #endif /* INET6 */ 621 struct tcpopt to; /* options in this segment */ 622 char *s = NULL; /* address and port logging */ 623 bool closed_port = false; /* segment is hitting a closed port */ 624 625 NET_EPOCH_ASSERT(); 626 627 #ifdef INET6 628 isipv6 = (mtod(m, struct ip *)->ip_v == 6) ? 1 : 0; 629 #endif 630 631 off0 = *offp; 632 m = *mp; 633 *mp = NULL; 634 to.to_flags = 0; 635 TCPSTAT_INC(tcps_rcvtotal); 636 637 m->m_pkthdr.tcp_tun_port = port; 638 #ifdef INET6 639 if (isipv6) { 640 ip6 = mtod(m, struct ip6_hdr *); 641 th = (struct tcphdr *)((caddr_t)ip6 + off0); 642 tlen = sizeof(*ip6) + ntohs(ip6->ip6_plen) - off0; 643 if (port) 644 goto skip6_csum; 645 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID_IPV6) { 646 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 647 th->th_sum = m->m_pkthdr.csum_data; 648 else 649 th->th_sum = in6_cksum_pseudo(ip6, tlen, 650 IPPROTO_TCP, m->m_pkthdr.csum_data); 651 th->th_sum ^= 0xffff; 652 } else if (m->m_pkthdr.csum_flags & CSUM_IP6_TCP) { 653 /* 654 * Packet from local host (maybe from a VM). 655 * Checksum not required. 656 */ 657 th->th_sum = 0; 658 } else 659 th->th_sum = in6_cksum(m, IPPROTO_TCP, off0, tlen); 660 if (th->th_sum) { 661 TCPSTAT_INC(tcps_rcvbadsum); 662 goto drop; 663 } 664 skip6_csum: 665 /* 666 * Be proactive about unspecified IPv6 address in source. 667 * As we use all-zero to indicate unbounded/unconnected pcb, 668 * unspecified IPv6 address can be used to confuse us. 669 * 670 * Note that packets with unspecified IPv6 destination is 671 * already dropped in ip6_input. 672 */ 673 KASSERT(!IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_dst), 674 ("%s: unspecified destination v6 address", __func__)); 675 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 676 IP6STAT_INC(ip6s_badscope); /* XXX */ 677 goto drop; 678 } 679 iptos = IPV6_TRAFFIC_CLASS(ip6); 680 } 681 #endif 682 #if defined(INET) && defined(INET6) 683 else 684 #endif 685 #ifdef INET 686 { 687 /* 688 * Get IP and TCP header together in first mbuf. 689 * Note: IP leaves IP header in first mbuf. 690 */ 691 if (off0 > sizeof (struct ip)) { 692 ip_stripoptions(m); 693 off0 = sizeof(struct ip); 694 } 695 if (m->m_len < sizeof (struct tcpiphdr)) { 696 if ((m = m_pullup(m, sizeof (struct tcpiphdr))) 697 == NULL) { 698 TCPSTAT_INC(tcps_rcvshort); 699 return (IPPROTO_DONE); 700 } 701 } 702 ip = mtod(m, struct ip *); 703 th = (struct tcphdr *)((caddr_t)ip + off0); 704 tlen = ntohs(ip->ip_len) - off0; 705 706 iptos = ip->ip_tos; 707 if (port) 708 goto skip_csum; 709 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) { 710 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 711 th->th_sum = m->m_pkthdr.csum_data; 712 else 713 th->th_sum = in_pseudo(ip->ip_src.s_addr, 714 ip->ip_dst.s_addr, 715 htonl(m->m_pkthdr.csum_data + tlen + 716 IPPROTO_TCP)); 717 th->th_sum ^= 0xffff; 718 } else if (m->m_pkthdr.csum_flags & CSUM_IP_TCP) { 719 /* 720 * Packet from local host (maybe from a VM). 721 * Checksum not required. 722 */ 723 th->th_sum = 0; 724 } else { 725 struct ipovly *ipov = (struct ipovly *)ip; 726 727 /* 728 * Checksum extended TCP header and data. 729 */ 730 len = off0 + tlen; 731 ipttl = ip->ip_ttl; 732 bzero(ipov->ih_x1, sizeof(ipov->ih_x1)); 733 ipov->ih_len = htons(tlen); 734 th->th_sum = in_cksum(m, len); 735 /* Reset length for SDT probes. */ 736 ip->ip_len = htons(len); 737 /* Reset TOS bits */ 738 ip->ip_tos = iptos; 739 /* Re-initialization for later version check */ 740 ip->ip_ttl = ipttl; 741 ip->ip_v = IPVERSION; 742 ip->ip_hl = off0 >> 2; 743 } 744 skip_csum: 745 if (th->th_sum && (port == 0)) { 746 TCPSTAT_INC(tcps_rcvbadsum); 747 goto drop; 748 } 749 KASSERT(ip->ip_dst.s_addr != INADDR_ANY, 750 ("%s: unspecified destination v4 address", __func__)); 751 if (__predict_false(ip->ip_src.s_addr == INADDR_ANY)) { 752 IPSTAT_INC(ips_badaddr); 753 goto drop; 754 } 755 } 756 #endif /* INET */ 757 758 /* 759 * Check that TCP offset makes sense, 760 * pull out TCP options and adjust length. XXX 761 */ 762 off = th->th_off << 2; 763 if (off < sizeof (struct tcphdr) || off > tlen) { 764 TCPSTAT_INC(tcps_rcvbadoff); 765 goto drop; 766 } 767 tlen -= off; /* tlen is used instead of ti->ti_len */ 768 if (off > sizeof (struct tcphdr)) { 769 #ifdef INET6 770 if (isipv6) { 771 if (m->m_len < off0 + off) { 772 m = m_pullup(m, off0 + off); 773 if (m == NULL) { 774 TCPSTAT_INC(tcps_rcvshort); 775 return (IPPROTO_DONE); 776 } 777 } 778 ip6 = mtod(m, struct ip6_hdr *); 779 th = (struct tcphdr *)((caddr_t)ip6 + off0); 780 } 781 #endif 782 #if defined(INET) && defined(INET6) 783 else 784 #endif 785 #ifdef INET 786 { 787 if (m->m_len < sizeof(struct ip) + off) { 788 if ((m = m_pullup(m, sizeof (struct ip) + off)) 789 == NULL) { 790 TCPSTAT_INC(tcps_rcvshort); 791 return (IPPROTO_DONE); 792 } 793 ip = mtod(m, struct ip *); 794 th = (struct tcphdr *)((caddr_t)ip + off0); 795 } 796 } 797 #endif 798 optlen = off - sizeof (struct tcphdr); 799 optp = (u_char *)(th + 1); 800 } 801 thflags = tcp_get_flags(th); 802 803 /* 804 * Convert TCP protocol specific fields to host format. 805 */ 806 tcp_fields_to_host(th); 807 808 /* 809 * Delay dropping TCP, IP headers, IPv6 ext headers, and TCP options. 810 */ 811 drop_hdrlen = off0 + off; 812 813 /* 814 * Grab info from PACKET_TAG_IPFORWARD tag prepended to the chain. 815 */ 816 if ( 817 #ifdef INET6 818 (isipv6 && (m->m_flags & M_IP6_NEXTHOP)) 819 #ifdef INET 820 || (!isipv6 && (m->m_flags & M_IP_NEXTHOP)) 821 #endif 822 #endif 823 #if defined(INET) && !defined(INET6) 824 (m->m_flags & M_IP_NEXTHOP) 825 #endif 826 ) 827 fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL); 828 829 /* 830 * For initial SYN packets we don't need write lock on matching 831 * PCB, be it a listening one or a synchronized one. The packet 832 * shall not modify its state. 833 */ 834 lookupflag = INPLOOKUP_WILDCARD | 835 ((thflags & (TH_ACK|TH_SYN)) == TH_SYN ? 836 INPLOOKUP_RLOCKPCB : INPLOOKUP_WLOCKPCB) | 837 (V_tcp_bind_all_fibs ? 0 : INPLOOKUP_FIB); 838 findpcb: 839 tp = NULL; 840 #ifdef INET6 841 if (isipv6 && fwd_tag != NULL) { 842 struct sockaddr_in6 *next_hop6; 843 844 next_hop6 = (struct sockaddr_in6 *)(fwd_tag + 1); 845 /* 846 * Transparently forwarded. Pretend to be the destination. 847 * Already got one like this? 848 */ 849 inp = in6_pcblookup_mbuf(&V_tcbinfo, 850 &ip6->ip6_src, th->th_sport, &ip6->ip6_dst, th->th_dport, 851 lookupflag & ~INPLOOKUP_WILDCARD, m->m_pkthdr.rcvif, m); 852 if (!inp) { 853 /* 854 * It's new. Try to find the ambushing socket. 855 * Because we've rewritten the destination address, 856 * any hardware-generated hash is ignored. 857 */ 858 inp = in6_pcblookup(&V_tcbinfo, &ip6->ip6_src, 859 th->th_sport, &next_hop6->sin6_addr, 860 next_hop6->sin6_port ? ntohs(next_hop6->sin6_port) : 861 th->th_dport, lookupflag, m->m_pkthdr.rcvif); 862 } 863 } else if (isipv6) { 864 inp = in6_pcblookup_mbuf(&V_tcbinfo, &ip6->ip6_src, 865 th->th_sport, &ip6->ip6_dst, th->th_dport, lookupflag, 866 m->m_pkthdr.rcvif, m); 867 } 868 #endif /* INET6 */ 869 #if defined(INET6) && defined(INET) 870 else 871 #endif 872 #ifdef INET 873 if (fwd_tag != NULL) { 874 struct sockaddr_in *next_hop; 875 876 next_hop = (struct sockaddr_in *)(fwd_tag+1); 877 /* 878 * Transparently forwarded. Pretend to be the destination. 879 * already got one like this? 880 */ 881 inp = in_pcblookup_mbuf(&V_tcbinfo, ip->ip_src, th->th_sport, 882 ip->ip_dst, th->th_dport, lookupflag & ~INPLOOKUP_WILDCARD, 883 m->m_pkthdr.rcvif, m); 884 if (!inp) { 885 /* 886 * It's new. Try to find the ambushing socket. 887 * Because we've rewritten the destination address, 888 * any hardware-generated hash is ignored. 889 */ 890 inp = in_pcblookup(&V_tcbinfo, ip->ip_src, 891 th->th_sport, next_hop->sin_addr, 892 next_hop->sin_port ? ntohs(next_hop->sin_port) : 893 th->th_dport, lookupflag, m->m_pkthdr.rcvif); 894 } 895 } else 896 inp = in_pcblookup_mbuf(&V_tcbinfo, ip->ip_src, 897 th->th_sport, ip->ip_dst, th->th_dport, lookupflag, 898 m->m_pkthdr.rcvif, m); 899 #endif /* INET */ 900 901 /* 902 * If the INPCB does not exist then all data in the incoming 903 * segment is discarded and an appropriate RST is sent back. 904 * XXX MRT Send RST using which routing table? 905 */ 906 if (inp == NULL) { 907 if ((lookupflag & INPLOOKUP_WILDCARD) == 0) { 908 /* We came here after second (safety) lookup. */ 909 MPASS(!closed_port); 910 } else { 911 /* 912 * Log communication attempts to ports that are not 913 * in use. 914 */ 915 if (((V_tcp_log_in_vain == 1 && (thflags & TH_SYN)) || 916 V_tcp_log_in_vain == 2) && 917 (s = tcp_log_vain(NULL, th, (void *)ip, ip6))) { 918 log(LOG_INFO, "%s; %s: Connection attempt " 919 "to closed port\n", s, __func__); 920 } 921 closed_port = true; 922 } 923 goto dropwithreset; 924 } 925 INP_LOCK_ASSERT(inp); 926 927 if ((inp->inp_flowtype == M_HASHTYPE_NONE) && 928 !SOLISTENING(inp->inp_socket)) { 929 if (M_HASHTYPE_GET(m) != M_HASHTYPE_NONE) { 930 inp->inp_flowid = m->m_pkthdr.flowid; 931 inp->inp_flowtype = M_HASHTYPE_GET(m); 932 #ifdef RSS 933 } else { 934 /* assign flowid by software RSS hash */ 935 #ifdef INET6 936 if (isipv6) { 937 rss_proto_software_hash_v6(&inp->in6p_faddr, 938 &inp->in6p_laddr, 939 inp->inp_fport, 940 inp->inp_lport, 941 IPPROTO_TCP, 942 &inp->inp_flowid, 943 &inp->inp_flowtype); 944 } else 945 #endif /* INET6 */ 946 { 947 rss_proto_software_hash_v4(inp->inp_faddr, 948 inp->inp_laddr, 949 inp->inp_fport, 950 inp->inp_lport, 951 IPPROTO_TCP, 952 &inp->inp_flowid, 953 &inp->inp_flowtype); 954 } 955 #endif /* RSS */ 956 } 957 } 958 #if defined(IPSEC) || defined(IPSEC_SUPPORT) 959 #ifdef INET6 960 if (isipv6 && IPSEC_ENABLED(ipv6) && 961 IPSEC_CHECK_POLICY(ipv6, m, inp) != 0) { 962 goto dropunlock; 963 } 964 #ifdef INET 965 else 966 #endif 967 #endif /* INET6 */ 968 #ifdef INET 969 if (IPSEC_ENABLED(ipv4) && 970 IPSEC_CHECK_POLICY(ipv4, m, inp) != 0) { 971 goto dropunlock; 972 } 973 #endif /* INET */ 974 #endif /* IPSEC */ 975 976 /* 977 * Check the minimum TTL for socket. 978 */ 979 if (inp->inp_ip_minttl != 0) { 980 #ifdef INET6 981 if (isipv6) { 982 if (inp->inp_ip_minttl > ip6->ip6_hlim) 983 goto dropunlock; 984 } else 985 #endif 986 if (inp->inp_ip_minttl > ip->ip_ttl) 987 goto dropunlock; 988 } 989 990 tp = intotcpcb(inp); 991 switch (tp->t_state) { 992 case TCPS_TIME_WAIT: 993 /* 994 * A previous connection in TIMEWAIT state is supposed to catch 995 * stray or duplicate segments arriving late. If this segment 996 * was a legitimate new connection attempt, the old INPCB gets 997 * removed and we can try again to find a listening socket. 998 */ 999 tcp_dooptions(&to, optp, optlen, 1000 (thflags & TH_SYN) ? TO_SYN : 0); 1001 /* 1002 * tcp_twcheck unlocks the inp always, and frees the m if fails. 1003 */ 1004 if (tcp_twcheck(inp, &to, th, m, tlen)) 1005 goto findpcb; 1006 return (IPPROTO_DONE); 1007 case TCPS_CLOSED: 1008 /* 1009 * The TCPCB may no longer exist if the connection is winding 1010 * down or it is in the CLOSED state. Either way we drop the 1011 * segment and send an appropriate response. 1012 */ 1013 closed_port = true; 1014 goto dropwithreset; 1015 } 1016 1017 if ((tp->t_port != port) && (tp->t_state > TCPS_LISTEN)) { 1018 closed_port = true; 1019 goto dropwithreset; 1020 } 1021 1022 #ifdef TCP_OFFLOAD 1023 if (tp->t_flags & TF_TOE) { 1024 tcp_offload_input(tp, m); 1025 m = NULL; /* consumed by the TOE driver */ 1026 goto dropunlock; 1027 } 1028 #endif 1029 1030 #ifdef MAC 1031 if (mac_inpcb_check_deliver(inp, m)) 1032 goto dropunlock; 1033 #endif 1034 so = inp->inp_socket; 1035 KASSERT(so != NULL, ("%s: so == NULL", __func__)); 1036 /* 1037 * When the socket is accepting connections (the INPCB is in LISTEN 1038 * state) we look into the SYN cache if this is a new connection 1039 * attempt or the completion of a previous one. 1040 */ 1041 KASSERT(tp->t_state == TCPS_LISTEN || !SOLISTENING(so), 1042 ("%s: so accepting but tp %p not listening", __func__, tp)); 1043 if (tp->t_state == TCPS_LISTEN && SOLISTENING(so)) { 1044 struct in_conninfo inc; 1045 1046 bzero(&inc, sizeof(inc)); 1047 #ifdef INET6 1048 if (isipv6) { 1049 inc.inc_flags |= INC_ISIPV6; 1050 if (inp->inp_inc.inc_flags & INC_IPV6MINMTU) 1051 inc.inc_flags |= INC_IPV6MINMTU; 1052 inc.inc6_faddr = ip6->ip6_src; 1053 inc.inc6_laddr = ip6->ip6_dst; 1054 } else 1055 #endif 1056 { 1057 inc.inc_faddr = ip->ip_src; 1058 inc.inc_laddr = ip->ip_dst; 1059 } 1060 inc.inc_fport = th->th_sport; 1061 inc.inc_lport = th->th_dport; 1062 inc.inc_fibnum = so->so_fibnum; 1063 1064 /* 1065 * Check for an existing connection attempt in syncache if 1066 * the flag is only ACK. A successful lookup creates a new 1067 * socket appended to the listen queue in SYN_RECEIVED state. 1068 */ 1069 if ((thflags & (TH_RST|TH_ACK|TH_SYN)) == TH_ACK) { 1070 int result; 1071 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 result = syncache_expand(&inc, &to, th, &so, m, port); 1082 if (result < 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 (result == 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, the missing 1102 * INPLOOKUP_WILDCARD flag in lookupflag would 1103 * hint the above code that the lookup was a 1104 * second attempt. 1105 * 1106 * NB: syncache did its own logging 1107 * of the failure cause. 1108 */ 1109 INP_WUNLOCK(inp); 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 goto dropwithreset; 1134 } else 1135 goto dropunlock; 1136 } 1137 /* 1138 * Socket is created in state SYN_RECEIVED. 1139 * Unlock the listen socket, lock the newly 1140 * created socket and update the tp variable. 1141 * If we came here via jump to tfo_socket_result, 1142 * then listening socket is read-locked. 1143 */ 1144 INP_UNLOCK(inp); /* listen socket */ 1145 inp = sotoinpcb(so); 1146 /* 1147 * New connection inpcb is already locked by 1148 * syncache_expand(). 1149 */ 1150 INP_WLOCK_ASSERT(inp); 1151 tp = intotcpcb(inp); 1152 KASSERT(tp->t_state == TCPS_SYN_RECEIVED, 1153 ("%s: ", __func__)); 1154 /* 1155 * Process the segment and the data it 1156 * contains. tcp_do_segment() consumes 1157 * the mbuf chain and unlocks the inpcb. 1158 */ 1159 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1160 tp->t_fb->tfb_tcp_do_segment(tp, m, th, drop_hdrlen, 1161 tlen, iptos); 1162 return (IPPROTO_DONE); 1163 } 1164 /* 1165 * Segment flag validation for new connection attempts: 1166 * 1167 * Our (SYN|ACK) response was rejected. 1168 * Check with syncache and remove entry to prevent 1169 * retransmits. 1170 * 1171 * NB: syncache_chkrst does its own logging of failure 1172 * causes. 1173 */ 1174 if (thflags & TH_RST) { 1175 syncache_chkrst(&inc, th, m, port); 1176 goto dropunlock; 1177 } 1178 /* 1179 * We can't do anything without SYN. 1180 */ 1181 if ((thflags & TH_SYN) == 0) { 1182 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1183 log(LOG_DEBUG, "%s; %s: Listen socket: " 1184 "SYN is missing, segment ignored\n", 1185 s, __func__); 1186 TCPSTAT_INC(tcps_badsyn); 1187 goto dropunlock; 1188 } 1189 /* 1190 * (SYN|ACK) is bogus on a listen socket. 1191 */ 1192 if (thflags & TH_ACK) { 1193 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1194 log(LOG_DEBUG, "%s; %s: Listen socket: " 1195 "SYN|ACK invalid, segment rejected\n", 1196 s, __func__); 1197 syncache_badack(&inc, port); /* XXX: Not needed! */ 1198 TCPSTAT_INC(tcps_badsyn); 1199 goto dropwithreset; 1200 } 1201 /* 1202 * If the drop_synfin option is enabled, drop all 1203 * segments with both the SYN and FIN bits set. 1204 * This prevents e.g. nmap from identifying the 1205 * TCP/IP stack. 1206 * XXX: Poor reasoning. nmap has other methods 1207 * and is constantly refining its stack detection 1208 * strategies. 1209 * XXX: This is a violation of the TCP specification 1210 * and was used by RFC1644. 1211 */ 1212 if ((thflags & TH_FIN) && V_drop_synfin) { 1213 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1214 log(LOG_DEBUG, "%s; %s: Listen socket: " 1215 "SYN|FIN segment ignored (based on " 1216 "sysctl setting)\n", s, __func__); 1217 TCPSTAT_INC(tcps_badsyn); 1218 goto dropunlock; 1219 } 1220 /* 1221 * Segment's flags are (SYN) or (SYN|FIN). 1222 * 1223 * TH_PUSH, TH_URG, TH_ECE, TH_CWR are ignored 1224 * as they do not affect the state of the TCP FSM. 1225 * The data pointed to by TH_URG and th_urp is ignored. 1226 */ 1227 KASSERT((thflags & (TH_RST|TH_ACK)) == 0, 1228 ("%s: Listen socket: TH_RST or TH_ACK set", __func__)); 1229 KASSERT(thflags & (TH_SYN), 1230 ("%s: Listen socket: TH_SYN not set", __func__)); 1231 INP_RLOCK_ASSERT(inp); 1232 #ifdef INET6 1233 /* 1234 * If deprecated address is forbidden, 1235 * we do not accept SYN to deprecated interface 1236 * address to prevent any new inbound connection from 1237 * getting established. 1238 * When we do not accept SYN, we send a TCP RST, 1239 * with deprecated source address (instead of dropping 1240 * it). We compromise it as it is much better for peer 1241 * to send a RST, and RST will be the final packet 1242 * for the exchange. 1243 * 1244 * If we do not forbid deprecated addresses, we accept 1245 * the SYN packet. RFC2462 does not suggest dropping 1246 * SYN in this case. 1247 * If we decipher RFC2462 5.5.4, it says like this: 1248 * 1. use of deprecated addr with existing 1249 * communication is okay - "SHOULD continue to be 1250 * used" 1251 * 2. use of it with new communication: 1252 * (2a) "SHOULD NOT be used if alternate address 1253 * with sufficient scope is available" 1254 * (2b) nothing mentioned otherwise. 1255 * Here we fall into (2b) case as we have no choice in 1256 * our source address selection - we must obey the peer. 1257 * 1258 * The wording in RFC2462 is confusing, and there are 1259 * multiple description text for deprecated address 1260 * handling - worse, they are not exactly the same. 1261 * I believe 5.5.4 is the best one, so we follow 5.5.4. 1262 */ 1263 if (isipv6 && !V_ip6_use_deprecated) { 1264 struct in6_ifaddr *ia6; 1265 1266 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false); 1267 if (ia6 != NULL && 1268 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) { 1269 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1270 log(LOG_DEBUG, "%s; %s: Listen socket: " 1271 "Connection attempt to deprecated " 1272 "IPv6 address rejected\n", 1273 s, __func__); 1274 goto dropwithreset; 1275 } 1276 } 1277 #endif /* INET6 */ 1278 /* 1279 * Basic sanity checks on incoming SYN requests: 1280 * Don't respond if the destination is a link layer 1281 * broadcast according to RFC1122 4.2.3.10, p. 104. 1282 * If it is from this socket it must be forged. 1283 * Don't respond if the source or destination is a 1284 * global or subnet broad- or multicast address. 1285 * Note that it is quite possible to receive unicast 1286 * link-layer packets with a broadcast IP address. Use 1287 * in_ifnet_broadcast() to find them. 1288 */ 1289 if (m->m_flags & (M_BCAST|M_MCAST)) { 1290 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1291 log(LOG_DEBUG, "%s; %s: Listen socket: " 1292 "Connection attempt from broad- or multicast " 1293 "link layer address ignored\n", s, __func__); 1294 goto dropunlock; 1295 } 1296 #ifdef INET6 1297 if (isipv6) { 1298 if (th->th_dport == th->th_sport && 1299 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &ip6->ip6_src)) { 1300 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1301 log(LOG_DEBUG, "%s; %s: Listen socket: " 1302 "Connection attempt to/from self " 1303 "ignored\n", s, __func__); 1304 goto dropunlock; 1305 } 1306 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 1307 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) { 1308 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1309 log(LOG_DEBUG, "%s; %s: Listen socket: " 1310 "Connection attempt from/to multicast " 1311 "address ignored\n", s, __func__); 1312 goto dropunlock; 1313 } 1314 } 1315 #endif 1316 #if defined(INET) && defined(INET6) 1317 else 1318 #endif 1319 #ifdef INET 1320 { 1321 if (th->th_dport == th->th_sport && 1322 ip->ip_dst.s_addr == ip->ip_src.s_addr) { 1323 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1324 log(LOG_DEBUG, "%s; %s: Listen socket: " 1325 "Connection attempt from/to self " 1326 "ignored\n", s, __func__); 1327 goto dropunlock; 1328 } 1329 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 1330 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 1331 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || 1332 in_ifnet_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) { 1333 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1334 log(LOG_DEBUG, "%s; %s: Listen socket: " 1335 "Connection attempt from/to broad- " 1336 "or multicast address ignored\n", 1337 s, __func__); 1338 goto dropunlock; 1339 } 1340 } 1341 #endif 1342 /* 1343 * SYN appears to be valid. Create compressed TCP state 1344 * for syncache. 1345 */ 1346 TCP_PROBE3(debug__input, tp, th, m); 1347 tcp_dooptions(&to, optp, optlen, TO_SYN); 1348 if ((so = syncache_add(&inc, &to, th, inp, so, m, NULL, NULL, 1349 iptos, port)) != NULL) 1350 goto tfo_socket_result; 1351 1352 /* 1353 * Entry added to syncache and mbuf consumed. 1354 * Only the listen socket is unlocked by syncache_add(). 1355 */ 1356 return (IPPROTO_DONE); 1357 } 1358 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 1359 if (tp->t_flags & TF_SIGNATURE) { 1360 tcp_dooptions(&to, optp, optlen, thflags); 1361 if ((to.to_flags & TOF_SIGNATURE) == 0) { 1362 TCPSTAT_INC(tcps_sig_err_nosigopt); 1363 goto dropunlock; 1364 } 1365 if (!TCPMD5_ENABLED() || 1366 TCPMD5_INPUT(m, th, to.to_signature) != 0) 1367 goto dropunlock; 1368 } 1369 #endif 1370 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1371 1372 /* 1373 * Segment belongs to a connection in SYN_SENT, ESTABLISHED or later 1374 * state. tcp_do_segment() always consumes the mbuf chain, unlocks 1375 * the inpcb, and unlocks pcbinfo. 1376 * 1377 * XXXGL: in case of a pure SYN arriving on existing connection 1378 * TCP stacks won't need to modify the PCB, they would either drop 1379 * the segment silently, or send a challenge ACK. However, we try 1380 * to upgrade the lock, because calling convention for stacks is 1381 * write-lock on PCB. If upgrade fails, drop the SYN. 1382 */ 1383 if ((lookupflag & INPLOOKUP_RLOCKPCB) && INP_TRY_UPGRADE(inp) == 0) 1384 goto dropunlock; 1385 1386 tp->t_fb->tfb_tcp_do_segment(tp, m, th, drop_hdrlen, tlen, iptos); 1387 return (IPPROTO_DONE); 1388 1389 dropwithreset: 1390 /* 1391 * When blackholing do not respond with a RST but 1392 * completely ignore the segment and drop it. 1393 */ 1394 if (((!closed_port && V_blackhole == 3) || 1395 (closed_port && 1396 ((V_blackhole == 1 && (thflags & TH_SYN)) || V_blackhole > 1))) && 1397 (V_blackhole_local || ( 1398 #ifdef INET6 1399 isipv6 ? !in6_localip(&ip6->ip6_src) : 1400 #endif 1401 #ifdef INET 1402 !in_localip(ip->ip_src) 1403 #else 1404 true 1405 #endif 1406 ))) 1407 goto dropunlock; 1408 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1409 tcp_dropwithreset(m, th, tp, tlen); 1410 m = NULL; /* mbuf chain got consumed. */ 1411 1412 dropunlock: 1413 if (m != NULL) 1414 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1415 1416 if (inp != NULL) 1417 INP_UNLOCK(inp); 1418 1419 drop: 1420 if (s != NULL) 1421 free(s, M_TCPLOG); 1422 if (m != NULL) 1423 m_freem(m); 1424 return (IPPROTO_DONE); 1425 } 1426 1427 /* 1428 * Automatic sizing of receive socket buffer. Often the send 1429 * buffer size is not optimally adjusted to the actual network 1430 * conditions at hand (delay bandwidth product). Setting the 1431 * buffer size too small limits throughput on links with high 1432 * bandwidth and high delay (eg. trans-continental/oceanic links). 1433 * 1434 * On the receive side the socket buffer memory is only rarely 1435 * used to any significant extent. This allows us to be much 1436 * more aggressive in scaling the receive socket buffer. For 1437 * the case that the buffer space is actually used to a large 1438 * extent and we run out of kernel memory we can simply drop 1439 * the new segments; TCP on the sender will just retransmit it 1440 * later. Setting the buffer size too big may only consume too 1441 * much kernel memory if the application doesn't read() from 1442 * the socket or packet loss or reordering makes use of the 1443 * reassembly queue. 1444 * 1445 * The criteria to step up the receive buffer one notch are: 1446 * 1. Application has not set receive buffer size with 1447 * SO_RCVBUF. Setting SO_RCVBUF clears SB_AUTOSIZE. 1448 * 2. the number of bytes received during 1/2 of an sRTT 1449 * is at least 3/8 of the current socket buffer size. 1450 * 3. receive buffer size has not hit maximal automatic size; 1451 * 1452 * If all of the criteria are met, we increase the socket buffer 1453 * by a 1/2 (bounded by the max). This allows us to keep ahead 1454 * of slow-start but also makes it so our peer never gets limited 1455 * by our rwnd which we then open up causing a burst. 1456 * 1457 * This algorithm does two steps per RTT at most and only if 1458 * we receive a bulk stream w/o packet losses or reorderings. 1459 * Shrinking the buffer during idle times is not necessary as 1460 * it doesn't consume any memory when idle. 1461 * 1462 * TODO: Only step up if the application is actually serving 1463 * the buffer to better manage the socket buffer resources. 1464 */ 1465 int 1466 tcp_autorcvbuf(struct mbuf *m, struct tcphdr *th, struct socket *so, 1467 struct tcpcb *tp, int tlen) 1468 { 1469 int newsize = 0; 1470 1471 if (V_tcp_do_autorcvbuf && (so->so_rcv.sb_flags & SB_AUTOSIZE) && 1472 tp->t_srtt != 0 && tp->rfbuf_ts != 0 && 1473 TCP_TS_TO_TICKS(tcp_ts_getticks() - tp->rfbuf_ts) > 1474 ((tp->t_srtt >> TCP_RTT_SHIFT)/2)) { 1475 if (tp->rfbuf_cnt > ((so->so_rcv.sb_hiwat / 2)/ 4 * 3) && 1476 so->so_rcv.sb_hiwat < V_tcp_autorcvbuf_max) { 1477 newsize = min((so->so_rcv.sb_hiwat + (so->so_rcv.sb_hiwat/2)), V_tcp_autorcvbuf_max); 1478 } 1479 TCP_PROBE6(receive__autoresize, NULL, tp, m, tp, th, newsize); 1480 1481 /* Start over with next RTT. */ 1482 tp->rfbuf_ts = 0; 1483 tp->rfbuf_cnt = 0; 1484 } else { 1485 tp->rfbuf_cnt += tlen; /* add up */ 1486 } 1487 return (newsize); 1488 } 1489 1490 int 1491 tcp_input(struct mbuf **mp, int *offp, int proto) 1492 { 1493 return(tcp_input_with_port(mp, offp, proto, 0)); 1494 } 1495 1496 static void 1497 tcp_handle_wakeup(struct tcpcb *tp) 1498 { 1499 1500 INP_WLOCK_ASSERT(tptoinpcb(tp)); 1501 1502 if (tp->t_flags & TF_WAKESOR) { 1503 struct socket *so = tptosocket(tp); 1504 1505 tp->t_flags &= ~TF_WAKESOR; 1506 SOCK_RECVBUF_LOCK_ASSERT(so); 1507 sorwakeup_locked(so); 1508 } 1509 } 1510 1511 void 1512 tcp_do_segment(struct tcpcb *tp, struct mbuf *m, struct tcphdr *th, 1513 int drop_hdrlen, int tlen, uint8_t iptos) 1514 { 1515 uint16_t thflags; 1516 int acked, ourfinisacked, needoutput = 0; 1517 sackstatus_t sack_changed; 1518 int todrop, win, incforsyn = 0; 1519 uint32_t tiwin; 1520 uint16_t nsegs; 1521 char *s; 1522 struct inpcb *inp = tptoinpcb(tp); 1523 struct socket *so = tptosocket(tp); 1524 struct in_conninfo *inc = &inp->inp_inc; 1525 struct mbuf *mfree; 1526 struct tcpopt to; 1527 int tfo_syn; 1528 u_int maxseg = 0; 1529 bool no_data; 1530 1531 no_data = (tlen == 0); 1532 thflags = tcp_get_flags(th); 1533 tp->sackhint.last_sack_ack = 0; 1534 sack_changed = SACK_NOCHANGE; 1535 nsegs = max(1, m->m_pkthdr.lro_nsegs); 1536 1537 NET_EPOCH_ASSERT(); 1538 INP_WLOCK_ASSERT(inp); 1539 KASSERT(tp->t_state > TCPS_LISTEN, ("%s: TCPS_LISTEN", 1540 __func__)); 1541 KASSERT(tp->t_state != TCPS_TIME_WAIT, ("%s: TCPS_TIME_WAIT", 1542 __func__)); 1543 1544 TCP_LOG_EVENT(tp, th, &so->so_rcv, &so->so_snd, TCP_LOG_IN, 0, 1545 tlen, NULL, true); 1546 1547 if ((thflags & TH_SYN) && (thflags & TH_FIN) && V_drop_synfin) { 1548 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1549 log(LOG_DEBUG, "%s; %s: " 1550 "SYN|FIN segment ignored (based on " 1551 "sysctl setting)\n", s, __func__); 1552 free(s, M_TCPLOG); 1553 } 1554 goto drop; 1555 } 1556 1557 /* 1558 * If a segment with the ACK-bit set arrives in the SYN-SENT state 1559 * check SEQ.ACK first. 1560 */ 1561 if ((tp->t_state == TCPS_SYN_SENT) && (thflags & TH_ACK) && 1562 (SEQ_LEQ(th->th_ack, tp->iss) || SEQ_GT(th->th_ack, tp->snd_max))) { 1563 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 1564 goto dropwithreset; 1565 } 1566 1567 /* 1568 * Segment received on connection. 1569 * Reset idle time and keep-alive timer. 1570 * XXX: This should be done after segment 1571 * validation to ignore broken/spoofed segs. 1572 */ 1573 if (tp->t_idle_reduce && 1574 (tp->snd_max == tp->snd_una) && 1575 ((ticks - tp->t_rcvtime) >= tp->t_rxtcur)) 1576 cc_after_idle(tp); 1577 tp->t_rcvtime = ticks; 1578 1579 if (thflags & TH_FIN) 1580 tcp_log_end_status(tp, TCP_EI_STATUS_CLIENT_FIN); 1581 /* 1582 * Scale up the window into a 32-bit value. 1583 * For the SYN_SENT state the scale is zero. 1584 */ 1585 tiwin = th->th_win << tp->snd_scale; 1586 #ifdef STATS 1587 stats_voi_update_abs_ulong(tp->t_stats, VOI_TCP_FRWIN, tiwin); 1588 #endif 1589 1590 /* 1591 * TCP ECN processing. 1592 */ 1593 if (tcp_ecn_input_segment(tp, thflags, tlen, 1594 tcp_packets_this_ack(tp, th->th_ack), 1595 iptos)) 1596 cc_cong_signal(tp, th, CC_ECN); 1597 1598 /* 1599 * Parse options on any incoming segment. 1600 */ 1601 tcp_dooptions(&to, (u_char *)(th + 1), 1602 (th->th_off << 2) - sizeof(struct tcphdr), 1603 (thflags & TH_SYN) ? TO_SYN : 0); 1604 if (tp->t_flags2 & TF2_PROC_SACK_PROHIBIT) { 1605 /* 1606 * We don't look at sack's from the 1607 * peer because the MSS is too small which 1608 * can subject us to an attack. 1609 */ 1610 to.to_flags &= ~TOF_SACK; 1611 } 1612 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 1613 if ((tp->t_flags & TF_SIGNATURE) != 0 && 1614 (to.to_flags & TOF_SIGNATURE) == 0) { 1615 TCPSTAT_INC(tcps_sig_err_sigopt); 1616 /* XXX: should drop? */ 1617 } 1618 #endif 1619 /* 1620 * If echoed timestamp is later than the current time, 1621 * fall back to non RFC1323 RTT calculation. Normalize 1622 * timestamp if syncookies were used when this connection 1623 * was established. 1624 */ 1625 if ((to.to_flags & TOF_TS) && (to.to_tsecr != 0)) { 1626 to.to_tsecr -= tp->ts_offset; 1627 if (TSTMP_GT(to.to_tsecr, tcp_ts_getticks())) { 1628 to.to_tsecr = 0; 1629 } 1630 } 1631 /* 1632 * Process options only when we get SYN/ACK back. The SYN case 1633 * for incoming connections is handled in tcp_syncache. 1634 * According to RFC1323 the window field in a SYN (i.e., a <SYN> 1635 * or <SYN,ACK>) segment itself is never scaled. 1636 * XXX this is traditional behavior, may need to be cleaned up. 1637 */ 1638 if (tp->t_state == TCPS_SYN_SENT && (thflags & TH_SYN)) { 1639 /* Handle parallel SYN for ECN */ 1640 tcp_ecn_input_parallel_syn(tp, thflags, iptos); 1641 if ((to.to_flags & TOF_SCALE) && 1642 (tp->t_flags & TF_REQ_SCALE) && 1643 !(tp->t_flags & TF_NOOPT)) { 1644 tp->t_flags |= TF_RCVD_SCALE; 1645 tp->snd_scale = to.to_wscale; 1646 } else { 1647 tp->t_flags &= ~TF_REQ_SCALE; 1648 } 1649 /* 1650 * Initial send window. It will be updated with 1651 * the next incoming segment to the scaled value. 1652 */ 1653 tp->snd_wnd = th->th_win; 1654 if ((to.to_flags & TOF_TS) && 1655 (tp->t_flags & TF_REQ_TSTMP) && 1656 !(tp->t_flags & TF_NOOPT)) { 1657 tp->t_flags |= TF_RCVD_TSTMP; 1658 tp->ts_recent = to.to_tsval; 1659 tp->ts_recent_age = tcp_ts_getticks(); 1660 } else { 1661 tp->t_flags &= ~TF_REQ_TSTMP; 1662 } 1663 if (to.to_flags & TOF_MSS) { 1664 tcp_mss(tp, to.to_mss); 1665 } 1666 if ((tp->t_flags & TF_SACK_PERMIT) && 1667 (!(to.to_flags & TOF_SACKPERM) || 1668 (tp->t_flags & TF_NOOPT))) { 1669 tp->t_flags &= ~TF_SACK_PERMIT; 1670 } 1671 if (tp->t_flags & TF_FASTOPEN) { 1672 if ((to.to_flags & TOF_FASTOPEN) && 1673 !(tp->t_flags & TF_NOOPT)) { 1674 uint16_t mss; 1675 1676 if (to.to_flags & TOF_MSS) { 1677 mss = to.to_mss; 1678 } else { 1679 if ((inp->inp_vflag & INP_IPV6) != 0) { 1680 mss = TCP6_MSS; 1681 } else { 1682 mss = TCP_MSS; 1683 } 1684 } 1685 tcp_fastopen_update_cache(tp, mss, 1686 to.to_tfo_len, to.to_tfo_cookie); 1687 } else { 1688 tcp_fastopen_disable_path(tp); 1689 } 1690 } 1691 } 1692 1693 /* 1694 * If timestamps were negotiated during SYN/ACK and a 1695 * segment without a timestamp is received, silently drop 1696 * the segment, unless it is a RST segment or missing timestamps are 1697 * tolerated. 1698 * See section 3.2 of RFC 7323. 1699 */ 1700 if ((tp->t_flags & TF_RCVD_TSTMP) && !(to.to_flags & TOF_TS)) { 1701 if (((thflags & TH_RST) != 0) || V_tcp_tolerate_missing_ts) { 1702 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1703 log(LOG_DEBUG, "%s; %s: Timestamp missing, " 1704 "segment processed normally\n", 1705 s, __func__); 1706 free(s, M_TCPLOG); 1707 } 1708 } else { 1709 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1710 log(LOG_DEBUG, "%s; %s: Timestamp missing, " 1711 "segment silently dropped\n", s, __func__); 1712 free(s, M_TCPLOG); 1713 } 1714 goto drop; 1715 } 1716 } 1717 /* 1718 * If timestamps were not negotiated during SYN/ACK and a 1719 * segment with a timestamp is received, ignore the 1720 * timestamp and process the packet normally. 1721 * See section 3.2 of RFC 7323. 1722 */ 1723 if (!(tp->t_flags & TF_RCVD_TSTMP) && (to.to_flags & TOF_TS)) { 1724 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1725 log(LOG_DEBUG, "%s; %s: Timestamp not expected, " 1726 "segment processed normally\n", s, __func__); 1727 free(s, M_TCPLOG); 1728 } 1729 } 1730 1731 /* 1732 * Header prediction: check for the two common cases 1733 * of a uni-directional data xfer. If the packet has 1734 * no control flags, is in-sequence, the window didn't 1735 * change and we're not retransmitting, it's a 1736 * candidate. If the length is zero and the ack moved 1737 * forward, we're the sender side of the xfer. Just 1738 * free the data acked & wake any higher level process 1739 * that was blocked waiting for space. If the length 1740 * is non-zero and the ack didn't move, we're the 1741 * receiver side. If we're getting packets in-order 1742 * (the reassembly queue is empty), add the data to 1743 * the socket buffer and note that we need a delayed ack. 1744 * Make sure that the hidden state-flags are also off. 1745 * Since we check for TCPS_ESTABLISHED first, it can only 1746 * be TH_NEEDSYN. 1747 */ 1748 if (tp->t_state == TCPS_ESTABLISHED && 1749 th->th_seq == tp->rcv_nxt && 1750 (thflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK && 1751 tp->snd_nxt == tp->snd_max && 1752 tiwin && tiwin == tp->snd_wnd && 1753 ((tp->t_flags & (TF_NEEDSYN|TF_NEEDFIN)) == 0) && 1754 SEGQ_EMPTY(tp) && 1755 ((to.to_flags & TOF_TS) == 0 || 1756 TSTMP_GEQ(to.to_tsval, tp->ts_recent)) ) { 1757 /* 1758 * If last ACK falls within this segment's sequence numbers, 1759 * record the timestamp. 1760 * NOTE that the test is modified according to the latest 1761 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 1762 */ 1763 if ((to.to_flags & TOF_TS) != 0 && 1764 SEQ_LEQ(th->th_seq, tp->last_ack_sent)) { 1765 tp->ts_recent_age = tcp_ts_getticks(); 1766 tp->ts_recent = to.to_tsval; 1767 } 1768 1769 if (no_data) { 1770 if (SEQ_GT(th->th_ack, tp->snd_una) && 1771 SEQ_LEQ(th->th_ack, tp->snd_max) && 1772 !IN_RECOVERY(tp->t_flags) && 1773 (to.to_flags & TOF_SACK) == 0 && 1774 TAILQ_EMPTY(&tp->snd_holes)) { 1775 /* 1776 * This is a pure ack for outstanding data. 1777 */ 1778 TCPSTAT_INC(tcps_predack); 1779 1780 /* 1781 * "bad retransmit" recovery. 1782 */ 1783 if (tp->t_rxtshift == 1 && 1784 tp->t_flags & TF_PREVVALID && 1785 tp->t_badrxtwin != 0 && 1786 (((to.to_flags & TOF_TS) != 0 && 1787 to.to_tsecr != 0 && 1788 TSTMP_LT(to.to_tsecr, tp->t_badrxtwin)) || 1789 ((to.to_flags & TOF_TS) == 0 && 1790 TSTMP_LT(ticks, tp->t_badrxtwin)))) 1791 cc_cong_signal(tp, th, CC_RTO_ERR); 1792 1793 /* 1794 * Recalculate the transmit timer / rtt. 1795 * 1796 * Some boxes send broken timestamp replies 1797 * during the SYN+ACK phase, ignore 1798 * timestamps of 0 or we could calculate a 1799 * huge RTT and blow up the retransmit timer. 1800 */ 1801 if ((to.to_flags & TOF_TS) != 0 && 1802 to.to_tsecr) { 1803 uint32_t t; 1804 1805 t = tcp_ts_getticks() - to.to_tsecr; 1806 if (!tp->t_rttlow || tp->t_rttlow > t) 1807 tp->t_rttlow = t; 1808 tcp_xmit_timer(tp, 1809 TCP_TS_TO_TICKS(t) + 1); 1810 } else if (tp->t_rtttime && 1811 SEQ_GT(th->th_ack, tp->t_rtseq)) { 1812 if (!tp->t_rttlow || 1813 tp->t_rttlow > ticks - tp->t_rtttime) 1814 tp->t_rttlow = ticks - tp->t_rtttime; 1815 tcp_xmit_timer(tp, 1816 ticks - tp->t_rtttime); 1817 } 1818 acked = BYTES_THIS_ACK(tp, th); 1819 1820 #ifdef TCP_HHOOK 1821 /* Run HHOOK_TCP_ESTABLISHED_IN helper hooks. */ 1822 hhook_run_tcp_est_in(tp, th, &to); 1823 #endif 1824 1825 TCPSTAT_ADD(tcps_rcvackpack, nsegs); 1826 TCPSTAT_ADD(tcps_rcvackbyte, acked); 1827 sbdrop(&so->so_snd, acked); 1828 if (SEQ_GT(tp->snd_una, tp->snd_recover) && 1829 SEQ_LEQ(th->th_ack, tp->snd_recover)) 1830 tp->snd_recover = th->th_ack - 1; 1831 1832 /* 1833 * Let the congestion control algorithm update 1834 * congestion control related information. This 1835 * typically means increasing the congestion 1836 * window. 1837 */ 1838 cc_ack_received(tp, th, nsegs, CC_ACK); 1839 1840 tp->snd_una = th->th_ack; 1841 /* 1842 * Pull snd_wl2 up to prevent seq wrap relative 1843 * to th_ack. 1844 */ 1845 tp->snd_wl2 = th->th_ack; 1846 tp->t_dupacks = 0; 1847 m_freem(m); 1848 1849 /* 1850 * If all outstanding data are acked, stop 1851 * retransmit timer, otherwise restart timer 1852 * using current (possibly backed-off) value. 1853 * If process is waiting for space, 1854 * wakeup/selwakeup/signal. If data 1855 * are ready to send, let tcp_output 1856 * decide between more output or persist. 1857 */ 1858 TCP_PROBE3(debug__input, tp, th, m); 1859 /* 1860 * Clear t_acktime if remote side has ACKd 1861 * all data in the socket buffer. 1862 * Otherwise, update t_acktime if we received 1863 * a sufficiently large ACK. 1864 */ 1865 if (sbavail(&so->so_snd) == 0) 1866 tp->t_acktime = 0; 1867 else if (acked > 1) 1868 tp->t_acktime = ticks; 1869 if (tp->snd_una == tp->snd_max) 1870 tcp_timer_activate(tp, TT_REXMT, 0); 1871 else if (!tcp_timer_active(tp, TT_PERSIST)) 1872 tcp_timer_activate(tp, TT_REXMT, 1873 TP_RXTCUR(tp)); 1874 sowwakeup(so); 1875 /* 1876 * Only call tcp_output when there 1877 * is new data available to be sent 1878 * or we need to send an ACK. 1879 */ 1880 if ((tp->t_flags & TF_ACKNOW) || 1881 (sbavail(&so->so_snd) >= 1882 SEQ_SUB(tp->snd_max, tp->snd_una))) { 1883 (void) tcp_output(tp); 1884 } 1885 goto check_delack; 1886 } 1887 } else if (th->th_ack == tp->snd_una && 1888 tlen <= sbspace(&so->so_rcv)) { 1889 int newsize = 0; /* automatic sockbuf scaling */ 1890 1891 /* 1892 * This is a pure, in-sequence data packet with 1893 * nothing on the reassembly queue and we have enough 1894 * buffer space to take it. 1895 */ 1896 /* Clean receiver SACK report if present */ 1897 if ((tp->t_flags & TF_SACK_PERMIT) && tp->rcv_numsacks) 1898 tcp_clean_sackreport(tp); 1899 TCPSTAT_INC(tcps_preddat); 1900 tp->rcv_nxt += tlen; 1901 if (tlen && 1902 ((tp->t_flags2 & TF2_FBYTES_COMPLETE) == 0) && 1903 (tp->t_fbyte_in == 0)) { 1904 tp->t_fbyte_in = ticks; 1905 if (tp->t_fbyte_in == 0) 1906 tp->t_fbyte_in = 1; 1907 if (tp->t_fbyte_out && tp->t_fbyte_in) 1908 tp->t_flags2 |= TF2_FBYTES_COMPLETE; 1909 } 1910 /* 1911 * Pull snd_wl1 up to prevent seq wrap relative to 1912 * th_seq. 1913 */ 1914 tp->snd_wl1 = th->th_seq; 1915 /* 1916 * Pull rcv_up up to prevent seq wrap relative to 1917 * rcv_nxt. 1918 */ 1919 tp->rcv_up = tp->rcv_nxt; 1920 TCPSTAT_ADD(tcps_rcvpack, nsegs); 1921 TCPSTAT_ADD(tcps_rcvbyte, tlen); 1922 TCP_PROBE3(debug__input, tp, th, m); 1923 1924 newsize = tcp_autorcvbuf(m, th, so, tp, tlen); 1925 1926 /* Add data to socket buffer. */ 1927 SOCK_RECVBUF_LOCK(so); 1928 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 1929 m_freem(m); 1930 } else { 1931 /* 1932 * Set new socket buffer size. 1933 * Give up when limit is reached. 1934 */ 1935 if (newsize) 1936 if (!sbreserve_locked(so, SO_RCV, 1937 newsize, NULL)) 1938 so->so_rcv.sb_flags &= ~SB_AUTOSIZE; 1939 m_adj(m, drop_hdrlen); /* delayed header drop */ 1940 sbappendstream_locked(&so->so_rcv, m, 0); 1941 } 1942 /* NB: sorwakeup_locked() does an implicit unlock. */ 1943 sorwakeup_locked(so); 1944 if (DELAY_ACK(tp, tlen)) { 1945 tp->t_flags |= TF_DELACK; 1946 } else { 1947 tp->t_flags |= TF_ACKNOW; 1948 (void) tcp_output(tp); 1949 } 1950 goto check_delack; 1951 } 1952 } 1953 1954 /* 1955 * Calculate amount of space in receive window, 1956 * and then do TCP input processing. 1957 * Receive window is amount of space in rcv queue, 1958 * but not less than advertised window. 1959 */ 1960 win = sbspace(&so->so_rcv); 1961 if (win < 0) 1962 win = 0; 1963 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 1964 1965 switch (tp->t_state) { 1966 /* 1967 * If the state is SYN_RECEIVED: 1968 * if seg contains an ACK, but not for our SYN/ACK, send a RST. 1969 */ 1970 case TCPS_SYN_RECEIVED: 1971 if (thflags & TH_RST) { 1972 /* Handle RST segments later. */ 1973 break; 1974 } 1975 if ((thflags & TH_ACK) && 1976 (SEQ_LEQ(th->th_ack, tp->snd_una) || 1977 SEQ_GT(th->th_ack, tp->snd_max))) { 1978 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 1979 goto dropwithreset; 1980 } 1981 if (tp->t_flags & TF_FASTOPEN) { 1982 /* 1983 * When a TFO connection is in SYN_RECEIVED, the 1984 * only valid packets are the initial SYN, a 1985 * retransmit/copy of the initial SYN (possibly with 1986 * a subset of the original data), a valid ACK, a 1987 * FIN, or a RST. 1988 */ 1989 if ((thflags & (TH_SYN|TH_ACK)) == (TH_SYN|TH_ACK)) { 1990 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 1991 goto dropwithreset; 1992 } else if (thflags & TH_SYN) { 1993 /* non-initial SYN is ignored */ 1994 if ((tcp_timer_active(tp, TT_DELACK) || 1995 tcp_timer_active(tp, TT_REXMT))) 1996 goto drop; 1997 } else if (!(thflags & (TH_ACK|TH_FIN|TH_RST))) { 1998 goto drop; 1999 } 2000 } 2001 break; 2002 2003 /* 2004 * If the state is SYN_SENT: 2005 * if seg contains a RST with valid ACK (SEQ.ACK has already 2006 * been verified), then drop the connection. 2007 * if seg contains a RST without an ACK, drop the seg. 2008 * if seg does not contain SYN, then drop the seg. 2009 * Otherwise this is an acceptable SYN segment 2010 * initialize tp->rcv_nxt and tp->irs 2011 * if seg contains ack then advance tp->snd_una 2012 * if seg contains an ECE and ECN support is enabled, the stream 2013 * is ECN capable. 2014 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 2015 * arrange for segment to be acked (eventually) 2016 * continue processing rest of data/controls, beginning with URG 2017 */ 2018 case TCPS_SYN_SENT: 2019 if ((thflags & (TH_ACK|TH_RST)) == (TH_ACK|TH_RST)) { 2020 TCP_PROBE5(connect__refused, NULL, tp, 2021 m, tp, th); 2022 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 2023 tp = tcp_drop(tp, ECONNREFUSED); 2024 } 2025 if (thflags & TH_RST) 2026 goto drop; 2027 if (!(thflags & TH_SYN)) 2028 goto drop; 2029 2030 tp->irs = th->th_seq; 2031 tcp_rcvseqinit(tp); 2032 if (thflags & TH_ACK) { 2033 int tfo_partial_ack = 0; 2034 2035 TCPSTAT_INC(tcps_connects); 2036 soisconnected(so); 2037 #ifdef MAC 2038 mac_socketpeer_set_from_mbuf(m, so); 2039 #endif 2040 /* Do window scaling on this connection? */ 2041 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2042 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2043 tp->rcv_scale = tp->request_r_scale; 2044 } 2045 tp->rcv_adv += min(tp->rcv_wnd, 2046 TCP_MAXWIN << tp->rcv_scale); 2047 tp->snd_una++; /* SYN is acked */ 2048 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2049 tp->snd_nxt = tp->snd_una; 2050 /* 2051 * If not all the data that was sent in the TFO SYN 2052 * has been acked, resend the remainder right away. 2053 */ 2054 if ((tp->t_flags & TF_FASTOPEN) && 2055 (tp->snd_una != tp->snd_max)) { 2056 tp->snd_nxt = th->th_ack; 2057 tfo_partial_ack = 1; 2058 } 2059 /* 2060 * If there's data, delay ACK; if there's also a FIN 2061 * ACKNOW will be turned on later. 2062 */ 2063 if (DELAY_ACK(tp, tlen) && tlen != 0 && !tfo_partial_ack) 2064 tcp_timer_activate(tp, TT_DELACK, 2065 tcp_delacktime); 2066 else 2067 tp->t_flags |= TF_ACKNOW; 2068 2069 tcp_ecn_input_syn_sent(tp, thflags, iptos); 2070 2071 /* 2072 * Received <SYN,ACK> in SYN_SENT[*] state. 2073 * Transitions: 2074 * SYN_SENT --> ESTABLISHED 2075 * SYN_SENT* --> FIN_WAIT_1 2076 */ 2077 tp->t_starttime = ticks; 2078 if (tp->t_flags & TF_NEEDFIN) { 2079 tp->t_acktime = ticks; 2080 tcp_state_change(tp, TCPS_FIN_WAIT_1); 2081 tp->t_flags &= ~TF_NEEDFIN; 2082 thflags &= ~TH_SYN; 2083 } else { 2084 tcp_state_change(tp, TCPS_ESTABLISHED); 2085 TCP_PROBE5(connect__established, NULL, tp, 2086 m, tp, th); 2087 cc_conn_init(tp); 2088 tcp_timer_activate(tp, TT_KEEP, 2089 TP_KEEPIDLE(tp)); 2090 } 2091 } else { 2092 /* 2093 * Received initial SYN in SYN-SENT[*] state => 2094 * simultaneous open. 2095 * If it succeeds, connection is * half-synchronized. 2096 * Otherwise, do 3-way handshake: 2097 * SYN-SENT -> SYN-RECEIVED 2098 * SYN-SENT* -> SYN-RECEIVED* 2099 */ 2100 tp->t_flags |= (TF_ACKNOW | TF_NEEDSYN | TF_SONOTCONN); 2101 tcp_timer_activate(tp, TT_REXMT, 0); 2102 tcp_state_change(tp, TCPS_SYN_RECEIVED); 2103 } 2104 2105 /* 2106 * Advance th->th_seq to correspond to first data byte. 2107 * If data, trim to stay within window, 2108 * dropping FIN if necessary. 2109 */ 2110 th->th_seq++; 2111 if (tlen > tp->rcv_wnd) { 2112 todrop = tlen - tp->rcv_wnd; 2113 m_adj(m, -todrop); 2114 tlen = tp->rcv_wnd; 2115 thflags &= ~TH_FIN; 2116 TCPSTAT_INC(tcps_rcvpackafterwin); 2117 TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); 2118 } 2119 tp->snd_wl1 = th->th_seq - 1; 2120 tp->rcv_up = th->th_seq; 2121 /* 2122 * Client side of transaction: already sent SYN and data. 2123 * If the remote host used T/TCP to validate the SYN, 2124 * our data will be ACK'd; if so, enter normal data segment 2125 * processing in the middle of step 5, ack processing. 2126 * Otherwise, goto step 6. 2127 */ 2128 if (thflags & TH_ACK) 2129 goto process_ACK; 2130 2131 goto step6; 2132 } 2133 2134 /* 2135 * States other than LISTEN or SYN_SENT. 2136 * First check the RST flag and sequence number since reset segments 2137 * are exempt from the timestamp and connection count tests. This 2138 * fixes a bug introduced by the Stevens, vol. 2, p. 960 bugfix 2139 * below which allowed reset segments in half the sequence space 2140 * to fall though and be processed (which gives forged reset 2141 * segments with a random sequence number a 50 percent chance of 2142 * killing a connection). 2143 * Then check timestamp, if present. 2144 * Then check the connection count, if present. 2145 * Then check that at least some bytes of segment are within 2146 * receive window. If segment begins before rcv_nxt, 2147 * drop leading data (and SYN); if nothing left, just ack. 2148 */ 2149 if (thflags & TH_RST) { 2150 /* 2151 * RFC5961 Section 3.2 2152 * 2153 * - RST drops connection only if SEG.SEQ == RCV.NXT. 2154 * - If RST is in window, we send challenge ACK. 2155 * 2156 * Note: to take into account delayed ACKs, we should 2157 * test against last_ack_sent instead of rcv_nxt. 2158 * Note 2: we handle special case of closed window, not 2159 * covered by the RFC. 2160 */ 2161 if ((SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 2162 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) || 2163 (tp->rcv_wnd == 0 && tp->last_ack_sent == th->th_seq)) { 2164 KASSERT(tp->t_state != TCPS_SYN_SENT, 2165 ("%s: TH_RST for TCPS_SYN_SENT th %p tp %p", 2166 __func__, th, tp)); 2167 2168 if (V_tcp_insecure_rst || 2169 tp->last_ack_sent == th->th_seq) { 2170 TCPSTAT_INC(tcps_drops); 2171 /* Drop the connection. */ 2172 switch (tp->t_state) { 2173 case TCPS_SYN_RECEIVED: 2174 so->so_error = ECONNREFUSED; 2175 goto close; 2176 case TCPS_ESTABLISHED: 2177 case TCPS_FIN_WAIT_1: 2178 case TCPS_FIN_WAIT_2: 2179 case TCPS_CLOSE_WAIT: 2180 case TCPS_CLOSING: 2181 case TCPS_LAST_ACK: 2182 so->so_error = ECONNRESET; 2183 close: 2184 /* FALLTHROUGH */ 2185 default: 2186 tcp_log_end_status(tp, TCP_EI_STATUS_CLIENT_RST); 2187 tp = tcp_close(tp); 2188 } 2189 } else { 2190 TCPSTAT_INC(tcps_badrst); 2191 tcp_send_challenge_ack(tp, th, m); 2192 m = NULL; 2193 } 2194 } 2195 goto drop; 2196 } 2197 2198 /* 2199 * RFC5961 Section 4.2 2200 * Send challenge ACK for any SYN in synchronized state. 2201 */ 2202 if ((thflags & TH_SYN) && tp->t_state != TCPS_SYN_SENT && 2203 tp->t_state != TCPS_SYN_RECEIVED) { 2204 TCPSTAT_INC(tcps_badsyn); 2205 if (V_tcp_insecure_syn && 2206 SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 2207 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) { 2208 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 2209 tp = tcp_drop(tp, ECONNRESET); 2210 } else { 2211 tcp_ecn_input_syn_sent(tp, thflags, iptos); 2212 tcp_send_challenge_ack(tp, th, m); 2213 m = NULL; 2214 } 2215 goto drop; 2216 } 2217 2218 /* 2219 * RFC 1323 PAWS: If we have a timestamp reply on this segment 2220 * and it's less than ts_recent, drop it. 2221 */ 2222 if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent && 2223 TSTMP_LT(to.to_tsval, tp->ts_recent)) { 2224 /* Check to see if ts_recent is over 24 days old. */ 2225 if (tcp_ts_getticks() - tp->ts_recent_age > TCP_PAWS_IDLE) { 2226 /* 2227 * Invalidate ts_recent. If this segment updates 2228 * ts_recent, the age will be reset later and ts_recent 2229 * will get a valid value. If it does not, setting 2230 * ts_recent to zero will at least satisfy the 2231 * requirement that zero be placed in the timestamp 2232 * echo reply when ts_recent isn't valid. The 2233 * age isn't reset until we get a valid ts_recent 2234 * because we don't want out-of-order segments to be 2235 * dropped when ts_recent is old. 2236 */ 2237 tp->ts_recent = 0; 2238 } else { 2239 TCPSTAT_INC(tcps_rcvduppack); 2240 TCPSTAT_ADD(tcps_rcvdupbyte, tlen); 2241 TCPSTAT_INC(tcps_pawsdrop); 2242 if (tlen) 2243 goto dropafterack; 2244 goto drop; 2245 } 2246 } 2247 2248 /* 2249 * In the SYN-RECEIVED state, validate that the packet belongs to 2250 * this connection before trimming the data to fit the receive 2251 * window. Check the sequence number versus IRS since we know 2252 * the sequence numbers haven't wrapped. This is a partial fix 2253 * for the "LAND" DoS attack. 2254 */ 2255 if (tp->t_state == TCPS_SYN_RECEIVED && SEQ_LT(th->th_seq, tp->irs)) { 2256 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 2257 goto dropwithreset; 2258 } 2259 2260 todrop = tp->rcv_nxt - th->th_seq; 2261 if (todrop > 0) { 2262 if (thflags & TH_SYN) { 2263 thflags &= ~TH_SYN; 2264 th->th_seq++; 2265 if (th->th_urp > 1) 2266 th->th_urp--; 2267 else 2268 thflags &= ~TH_URG; 2269 todrop--; 2270 } 2271 /* 2272 * Following if statement from Stevens, vol. 2, p. 960. 2273 */ 2274 if (todrop > tlen 2275 || (todrop == tlen && (thflags & TH_FIN) == 0)) { 2276 /* 2277 * Any valid FIN must be to the left of the window. 2278 * At this point the FIN must be a duplicate or out 2279 * of sequence; drop it. 2280 */ 2281 thflags &= ~TH_FIN; 2282 2283 /* 2284 * Send an ACK to resynchronize and drop any data. 2285 * But keep on processing for RST or ACK. 2286 */ 2287 tp->t_flags |= TF_ACKNOW; 2288 todrop = tlen; 2289 TCPSTAT_INC(tcps_rcvduppack); 2290 TCPSTAT_ADD(tcps_rcvdupbyte, todrop); 2291 } else { 2292 TCPSTAT_INC(tcps_rcvpartduppack); 2293 TCPSTAT_ADD(tcps_rcvpartdupbyte, todrop); 2294 } 2295 /* 2296 * DSACK - add SACK block for dropped range 2297 */ 2298 if ((todrop > 0) && (tp->t_flags & TF_SACK_PERMIT)) { 2299 tcp_update_sack_list(tp, th->th_seq, 2300 th->th_seq + todrop); 2301 /* 2302 * ACK now, as the next in-sequence segment 2303 * will clear the DSACK block again 2304 */ 2305 tp->t_flags |= TF_ACKNOW; 2306 } 2307 drop_hdrlen += todrop; /* drop from the top afterwards */ 2308 th->th_seq += todrop; 2309 tlen -= todrop; 2310 if (th->th_urp > todrop) 2311 th->th_urp -= todrop; 2312 else { 2313 thflags &= ~TH_URG; 2314 th->th_urp = 0; 2315 } 2316 } 2317 2318 /* 2319 * If new data are received on a connection after the 2320 * user processes are gone, then RST the other end if 2321 * no FIN has been processed. 2322 */ 2323 if ((tp->t_flags & TF_CLOSED) && tlen > 0 && 2324 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2325 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 2326 log(LOG_DEBUG, "%s; %s: %s: Received %d bytes of data " 2327 "after socket was closed, " 2328 "sending RST and removing tcpcb\n", 2329 s, __func__, tcpstates[tp->t_state], tlen); 2330 free(s, M_TCPLOG); 2331 } 2332 tcp_log_end_status(tp, TCP_EI_STATUS_DATA_A_CLOSE); 2333 /* tcp_close will kill the inp pre-log the Reset */ 2334 tcp_log_end_status(tp, TCP_EI_STATUS_SERVER_RST); 2335 tp = tcp_close(tp); 2336 TCPSTAT_INC(tcps_rcvafterclose); 2337 goto dropwithreset; 2338 } 2339 2340 /* 2341 * If segment ends after window, drop trailing data 2342 * (and PUSH and FIN); if nothing left, just ACK. 2343 */ 2344 todrop = (th->th_seq + tlen) - (tp->rcv_nxt + tp->rcv_wnd); 2345 if (todrop > 0) { 2346 TCPSTAT_INC(tcps_rcvpackafterwin); 2347 if (todrop >= tlen) { 2348 TCPSTAT_ADD(tcps_rcvbyteafterwin, tlen); 2349 /* 2350 * If window is closed can only take segments at 2351 * window edge, and have to drop data and PUSH from 2352 * incoming segments. Continue processing, but 2353 * remember to ack. Otherwise, drop segment 2354 * and ack. 2355 */ 2356 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 2357 tp->t_flags |= TF_ACKNOW; 2358 TCPSTAT_INC(tcps_rcvwinprobe); 2359 } else 2360 goto dropafterack; 2361 } else 2362 TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); 2363 m_adj(m, -todrop); 2364 tlen -= todrop; 2365 thflags &= ~(TH_PUSH|TH_FIN); 2366 } 2367 2368 /* 2369 * If last ACK falls within this segment's sequence numbers, 2370 * record its timestamp. 2371 * NOTE: 2372 * 1) That the test incorporates suggestions from the latest 2373 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 2374 * 2) That updating only on newer timestamps interferes with 2375 * our earlier PAWS tests, so this check should be solely 2376 * predicated on the sequence space of this segment. 2377 * 3) That we modify the segment boundary check to be 2378 * Last.ACK.Sent <= SEG.SEQ + SEG.Len 2379 * instead of RFC1323's 2380 * Last.ACK.Sent < SEG.SEQ + SEG.Len, 2381 * This modified check allows us to overcome RFC1323's 2382 * limitations as described in Stevens TCP/IP Illustrated 2383 * Vol. 2 p.869. In such cases, we can still calculate the 2384 * RTT correctly when RCV.NXT == Last.ACK.Sent. 2385 */ 2386 if ((to.to_flags & TOF_TS) != 0 && 2387 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 2388 SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen + 2389 ((thflags & (TH_SYN|TH_FIN)) != 0))) { 2390 tp->ts_recent_age = tcp_ts_getticks(); 2391 tp->ts_recent = to.to_tsval; 2392 } 2393 2394 /* 2395 * If the ACK bit is off: if in SYN-RECEIVED state or SENDSYN 2396 * flag is on (half-synchronized state), then queue data for 2397 * later processing; else drop segment and return. 2398 */ 2399 if ((thflags & TH_ACK) == 0) { 2400 if (tp->t_state == TCPS_SYN_RECEIVED || 2401 (tp->t_flags & TF_NEEDSYN)) { 2402 if (tp->t_state == TCPS_SYN_RECEIVED && 2403 (tp->t_flags & TF_FASTOPEN)) { 2404 tp->snd_wnd = tiwin; 2405 cc_conn_init(tp); 2406 } 2407 goto step6; 2408 } else if (tp->t_flags & TF_ACKNOW) 2409 goto dropafterack; 2410 else 2411 goto drop; 2412 } 2413 2414 /* 2415 * Ack processing. 2416 */ 2417 if (SEQ_GEQ(tp->snd_una, tp->iss + (TCP_MAXWIN << tp->snd_scale))) { 2418 /* Checking SEG.ACK against ISS is definitely redundant. */ 2419 tp->t_flags2 |= TF2_NO_ISS_CHECK; 2420 } 2421 if (!V_tcp_insecure_ack) { 2422 tcp_seq seq_min; 2423 bool ghost_ack_check; 2424 2425 if (tp->t_flags2 & TF2_NO_ISS_CHECK) { 2426 /* Check for too old ACKs (RFC 5961, Section 5.2). */ 2427 seq_min = tp->snd_una - tp->max_sndwnd; 2428 ghost_ack_check = false; 2429 } else { 2430 if (SEQ_GT(tp->iss + 1, tp->snd_una - tp->max_sndwnd)) { 2431 /* Checking for ghost ACKs is stricter. */ 2432 seq_min = tp->iss + 1; 2433 ghost_ack_check = true; 2434 } else { 2435 /* 2436 * Checking for too old ACKs (RFC 5961, 2437 * Section 5.2) is stricter. 2438 */ 2439 seq_min = tp->snd_una - tp->max_sndwnd; 2440 ghost_ack_check = false; 2441 } 2442 } 2443 if (SEQ_LT(th->th_ack, seq_min)) { 2444 if (ghost_ack_check) 2445 TCPSTAT_INC(tcps_rcvghostack); 2446 else 2447 TCPSTAT_INC(tcps_rcvacktooold); 2448 tcp_send_challenge_ack(tp, th, m); 2449 m = NULL; 2450 goto drop; 2451 } 2452 } 2453 switch (tp->t_state) { 2454 /* 2455 * In SYN_RECEIVED state, the ack ACKs our SYN, so enter 2456 * ESTABLISHED state and continue processing. 2457 * The ACK was checked above. 2458 */ 2459 case TCPS_SYN_RECEIVED: 2460 2461 TCPSTAT_INC(tcps_connects); 2462 if (tp->t_flags & TF_SONOTCONN) { 2463 /* 2464 * Usually SYN_RECEIVED had been created from a LISTEN, 2465 * and solisten_enqueue() has already marked the socket 2466 * layer as connected. If it didn't, which can happen 2467 * only with an accept_filter(9), then the tp is marked 2468 * with TF_SONOTCONN. The other reason for this mark 2469 * to be set is a simultaneous open, a SYN_RECEIVED 2470 * that had been created from SYN_SENT. 2471 */ 2472 tp->t_flags &= ~TF_SONOTCONN; 2473 soisconnected(so); 2474 } 2475 /* Do window scaling? */ 2476 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2477 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2478 tp->rcv_scale = tp->request_r_scale; 2479 } 2480 tp->snd_wnd = tiwin; 2481 /* 2482 * Make transitions: 2483 * SYN-RECEIVED -> ESTABLISHED 2484 * SYN-RECEIVED* -> FIN-WAIT-1 2485 */ 2486 tp->t_starttime = ticks; 2487 if ((tp->t_flags & TF_FASTOPEN) && tp->t_tfo_pending) { 2488 tcp_fastopen_decrement_counter(tp->t_tfo_pending); 2489 tp->t_tfo_pending = NULL; 2490 } 2491 if (tp->t_flags & TF_NEEDFIN) { 2492 tp->t_acktime = ticks; 2493 tcp_state_change(tp, TCPS_FIN_WAIT_1); 2494 tp->t_flags &= ~TF_NEEDFIN; 2495 } else { 2496 tcp_state_change(tp, TCPS_ESTABLISHED); 2497 TCP_PROBE5(accept__established, NULL, tp, 2498 m, tp, th); 2499 /* 2500 * TFO connections call cc_conn_init() during SYN 2501 * processing. Calling it again here for such 2502 * connections is not harmless as it would undo the 2503 * snd_cwnd reduction that occurs when a TFO SYN|ACK 2504 * is retransmitted. 2505 */ 2506 if (!(tp->t_flags & TF_FASTOPEN)) 2507 cc_conn_init(tp); 2508 tcp_timer_activate(tp, TT_KEEP, TP_KEEPIDLE(tp)); 2509 } 2510 /* 2511 * Account for the ACK of our SYN prior to 2512 * regular ACK processing below, except for 2513 * simultaneous SYN, which is handled later. 2514 */ 2515 if (SEQ_GT(th->th_ack, tp->snd_una) && !(tp->t_flags & TF_NEEDSYN)) 2516 incforsyn = 1; 2517 /* 2518 * If segment contains data or ACK, will call tcp_reass() 2519 * later; if not, do so now to pass queued data to user. 2520 */ 2521 if (tlen == 0 && (thflags & TH_FIN) == 0) { 2522 (void) tcp_reass(tp, (struct tcphdr *)0, NULL, 0, 2523 (struct mbuf *)0); 2524 tcp_handle_wakeup(tp); 2525 } 2526 tp->snd_wl1 = th->th_seq - 1; 2527 /* FALLTHROUGH */ 2528 2529 /* 2530 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 2531 * ACKs. If the ack is in the range 2532 * tp->snd_una < th->th_ack <= tp->snd_max 2533 * then advance tp->snd_una to th->th_ack and drop 2534 * data from the retransmission queue. If this ACK reflects 2535 * more up to date window information we update our window information. 2536 */ 2537 case TCPS_ESTABLISHED: 2538 case TCPS_FIN_WAIT_1: 2539 case TCPS_FIN_WAIT_2: 2540 case TCPS_CLOSE_WAIT: 2541 case TCPS_CLOSING: 2542 case TCPS_LAST_ACK: 2543 if (SEQ_GT(th->th_ack, tp->snd_max)) { 2544 TCPSTAT_INC(tcps_rcvacktoomuch); 2545 goto dropafterack; 2546 } 2547 if (tcp_is_sack_recovery(tp, &to)) { 2548 sack_changed = tcp_sack_doack(tp, &to, th->th_ack); 2549 if ((sack_changed != SACK_NOCHANGE) && 2550 (tp->t_flags & TF_LRD)) { 2551 tcp_sack_lost_retransmission(tp, th); 2552 } 2553 } else 2554 /* 2555 * Reset the value so that previous (valid) value 2556 * from the last ack with SACK doesn't get used. 2557 */ 2558 tp->sackhint.sacked_bytes = 0; 2559 2560 #ifdef TCP_HHOOK 2561 /* Run HHOOK_TCP_ESTABLISHED_IN helper hooks. */ 2562 hhook_run_tcp_est_in(tp, th, &to); 2563 #endif 2564 2565 if (SEQ_LT(th->th_ack, tp->snd_una)) { 2566 /* This is old ACK information, don't process it. */ 2567 break; 2568 } 2569 if (th->th_ack == tp->snd_una) { 2570 /* Check if this is a duplicate ACK. */ 2571 if ((tp->t_flags & TF_SACK_PERMIT) && 2572 V_tcp_do_newsack) { 2573 /* 2574 * If SEG.ACK == SND.UNA, RFC 6675 requires a 2575 * duplicate ACK to selectively acknowledge 2576 * at least one byte, which was not selectively 2577 * acknowledged before. 2578 */ 2579 if (sack_changed == SACK_NOCHANGE) { 2580 break; 2581 } 2582 } else { 2583 /* 2584 * If SEG.ACK == SND.UNA, RFC 5681 requires a 2585 * duplicate ACK to have no data on it and to 2586 * not be a window update. 2587 */ 2588 if (!no_data || tiwin != tp->snd_wnd) { 2589 break; 2590 } 2591 } 2592 /* 2593 * If this is the first time we've seen a 2594 * FIN from the remote, this is not a 2595 * duplicate ACK and it needs to be processed 2596 * normally. 2597 * This happens during a simultaneous close. 2598 */ 2599 if ((thflags & TH_FIN) && 2600 (TCPS_HAVERCVDFIN(tp->t_state) == 0)) { 2601 tp->t_dupacks = 0; 2602 break; 2603 } 2604 /* Perform duplicate ACK processing. */ 2605 TCPSTAT_INC(tcps_rcvdupack); 2606 maxseg = tcp_maxseg(tp); 2607 if (!tcp_timer_active(tp, TT_REXMT)) { 2608 tp->t_dupacks = 0; 2609 } else if (++tp->t_dupacks > tcprexmtthresh || 2610 IN_FASTRECOVERY(tp->t_flags)) { 2611 cc_ack_received(tp, th, nsegs, CC_DUPACK); 2612 if (V_tcp_do_prr && 2613 IN_FASTRECOVERY(tp->t_flags) && 2614 (tp->t_flags & TF_SACK_PERMIT)) { 2615 tcp_do_prr_ack(tp, th, &to, 2616 sack_changed, &maxseg); 2617 } else if (tcp_is_sack_recovery(tp, &to) && 2618 IN_FASTRECOVERY(tp->t_flags) && 2619 (tp->snd_nxt == tp->snd_max)) { 2620 int awnd; 2621 2622 /* 2623 * Compute the amount of data in flight first. 2624 * We can inject new data into the pipe iff 2625 * we have less than ssthresh 2626 * worth of data in flight. 2627 */ 2628 awnd = tcp_compute_pipe(tp); 2629 if (awnd < tp->snd_ssthresh) { 2630 tp->snd_cwnd += imax(maxseg, 2631 imin(2 * maxseg, 2632 tp->sackhint.delivered_data)); 2633 if (tp->snd_cwnd > tp->snd_ssthresh) 2634 tp->snd_cwnd = tp->snd_ssthresh; 2635 } 2636 } else if (tcp_is_sack_recovery(tp, &to) && 2637 IN_FASTRECOVERY(tp->t_flags) && 2638 SEQ_LT(tp->snd_nxt, tp->snd_max)) { 2639 tp->snd_cwnd += imax(maxseg, 2640 imin(2 * maxseg, 2641 tp->sackhint.delivered_data)); 2642 } else { 2643 tp->snd_cwnd += maxseg; 2644 } 2645 (void) tcp_output(tp); 2646 goto drop; 2647 } else if (tp->t_dupacks == tcprexmtthresh || 2648 (tp->t_flags & TF_SACK_PERMIT && 2649 V_tcp_do_newsack && 2650 tp->sackhint.sacked_bytes > 2651 (tcprexmtthresh - 1) * maxseg)) { 2652 enter_recovery: 2653 /* 2654 * Above is the RFC6675 trigger condition of 2655 * more than (dupthresh-1)*maxseg sacked data. 2656 * If the count of holes in the 2657 * scoreboard is >= dupthresh, we could 2658 * also enter loss recovery, but don't 2659 * have that value readily available. 2660 */ 2661 tp->t_dupacks = tcprexmtthresh; 2662 tcp_seq onxt = tp->snd_nxt; 2663 2664 /* 2665 * If we're doing sack, check to 2666 * see if we're already in sack 2667 * recovery. If we're not doing sack, 2668 * check to see if we're in newreno 2669 * recovery. 2670 */ 2671 if (tcp_is_sack_recovery(tp, &to)) { 2672 if (IN_FASTRECOVERY(tp->t_flags)) { 2673 tp->t_dupacks = 0; 2674 break; 2675 } 2676 } else { 2677 if (SEQ_LEQ(th->th_ack, 2678 tp->snd_recover)) { 2679 tp->t_dupacks = 0; 2680 break; 2681 } 2682 } 2683 /* Congestion signal before ack. */ 2684 cc_cong_signal(tp, th, CC_NDUPACK); 2685 cc_ack_received(tp, th, nsegs, CC_DUPACK); 2686 tcp_timer_activate(tp, TT_REXMT, 0); 2687 tp->t_rtttime = 0; 2688 if (V_tcp_do_prr) { 2689 /* 2690 * snd_ssthresh and snd_recover are 2691 * already updated by cc_cong_signal. 2692 */ 2693 if (tcp_is_sack_recovery(tp, &to)) { 2694 /* 2695 * Include Limited Transmit 2696 * segments here 2697 */ 2698 tp->sackhint.prr_delivered = 2699 imin(tp->snd_max - th->th_ack, 2700 (tp->snd_limited + 1) * maxseg); 2701 } else { 2702 tp->sackhint.prr_delivered = 2703 maxseg; 2704 } 2705 tp->sackhint.recover_fs = max(1, 2706 tp->snd_nxt - tp->snd_una); 2707 } 2708 tp->snd_limited = 0; 2709 if (tcp_is_sack_recovery(tp, &to)) { 2710 TCPSTAT_INC(tcps_sack_recovery_episode); 2711 /* 2712 * When entering LR after RTO due to 2713 * Duplicate ACKs, retransmit existing 2714 * holes from the scoreboard. 2715 */ 2716 tcp_resend_sackholes(tp); 2717 /* Avoid inflating cwnd in tcp_output */ 2718 tp->snd_nxt = tp->snd_max; 2719 tp->snd_cwnd = tcp_compute_pipe(tp) + 2720 maxseg; 2721 (void) tcp_output(tp); 2722 /* Set cwnd to the expected flightsize */ 2723 tp->snd_cwnd = tp->snd_ssthresh; 2724 goto drop; 2725 } 2726 tp->snd_nxt = th->th_ack; 2727 tp->snd_cwnd = maxseg; 2728 (void) tcp_output(tp); 2729 KASSERT(tp->snd_limited <= 2, 2730 ("%s: tp->snd_limited too big", 2731 __func__)); 2732 tp->snd_cwnd = tp->snd_ssthresh + 2733 maxseg * 2734 (tp->t_dupacks - tp->snd_limited); 2735 if (SEQ_GT(onxt, tp->snd_nxt)) 2736 tp->snd_nxt = onxt; 2737 goto drop; 2738 } else if (V_tcp_do_rfc3042) { 2739 /* 2740 * Process first and second duplicate 2741 * ACKs. Each indicates a segment 2742 * leaving the network, creating room 2743 * for more. Make sure we can send a 2744 * packet on reception of each duplicate 2745 * ACK by increasing snd_cwnd by one 2746 * segment. Restore the original 2747 * snd_cwnd after packet transmission. 2748 */ 2749 cc_ack_received(tp, th, nsegs, CC_DUPACK); 2750 uint32_t oldcwnd = tp->snd_cwnd; 2751 tcp_seq oldsndmax = tp->snd_max; 2752 u_int sent; 2753 int avail; 2754 2755 KASSERT(tp->t_dupacks == 1 || 2756 tp->t_dupacks == 2, 2757 ("%s: dupacks not 1 or 2", 2758 __func__)); 2759 if (tp->t_dupacks == 1) 2760 tp->snd_limited = 0; 2761 if ((tp->snd_nxt == tp->snd_max) && 2762 (tp->t_rxtshift == 0)) 2763 tp->snd_cwnd = 2764 SEQ_SUB(tp->snd_nxt, tp->snd_una); 2765 tp->snd_cwnd += 2766 (tp->t_dupacks - tp->snd_limited) * maxseg; 2767 tp->snd_cwnd -= tcp_sack_adjust(tp); 2768 /* 2769 * Only call tcp_output when there 2770 * is new data available to be sent 2771 * or we need to send an ACK. 2772 */ 2773 SOCK_SENDBUF_LOCK(so); 2774 avail = sbavail(&so->so_snd); 2775 SOCK_SENDBUF_UNLOCK(so); 2776 if (tp->t_flags & TF_ACKNOW || 2777 (avail >= 2778 SEQ_SUB(tp->snd_nxt, tp->snd_una))) { 2779 (void) tcp_output(tp); 2780 } 2781 sent = SEQ_SUB(tp->snd_max, oldsndmax); 2782 if (sent > maxseg) { 2783 KASSERT((tp->t_dupacks == 2 && 2784 tp->snd_limited == 0) || 2785 (sent == maxseg + 1 && 2786 tp->t_flags & TF_SENTFIN) || 2787 (sent < 2 * maxseg && 2788 tp->t_flags & TF_NODELAY), 2789 ("%s: sent too much: %u>%u", 2790 __func__, sent, maxseg)); 2791 tp->snd_limited = 2; 2792 } else if (sent > 0) { 2793 ++tp->snd_limited; 2794 } 2795 tp->snd_cwnd = oldcwnd; 2796 goto drop; 2797 } 2798 break; 2799 } 2800 KASSERT(SEQ_GT(th->th_ack, tp->snd_una), 2801 ("%s: SEQ_LEQ(th_ack, snd_una)", __func__)); 2802 /* 2803 * This ack is advancing the left edge, reset the 2804 * counter. 2805 */ 2806 tp->t_dupacks = 0; 2807 /* 2808 * If this ack also has new SACK info, increment the 2809 * t_dupacks as per RFC 6675. The variable 2810 * sack_changed tracks all changes to the SACK 2811 * scoreboard, including when partial ACKs without 2812 * SACK options are received, and clear the scoreboard 2813 * from the left side. Such partial ACKs should not be 2814 * counted as dupacks here. 2815 */ 2816 if (V_tcp_do_newsack && 2817 tcp_is_sack_recovery(tp, &to) && 2818 (((tp->t_rxtshift == 0) && (sack_changed != SACK_NOCHANGE)) || 2819 ((tp->t_rxtshift > 0) && (sack_changed == SACK_NEWLOSS))) && 2820 (tp->snd_nxt == tp->snd_max)) { 2821 tp->t_dupacks++; 2822 /* limit overhead by setting maxseg last */ 2823 if (!IN_FASTRECOVERY(tp->t_flags) && 2824 (tp->sackhint.sacked_bytes > 2825 (tcprexmtthresh - 1) * (maxseg = tcp_maxseg(tp)))) { 2826 goto enter_recovery; 2827 } 2828 } 2829 /* 2830 * If the congestion window was inflated to account 2831 * for the other side's cached packets, retract it. 2832 */ 2833 if (SEQ_LT(th->th_ack, tp->snd_recover)) { 2834 if (IN_FASTRECOVERY(tp->t_flags)) { 2835 if (tp->t_flags & TF_SACK_PERMIT) { 2836 if (V_tcp_do_prr && 2837 (to.to_flags & TOF_SACK)) { 2838 tcp_timer_activate(tp, 2839 TT_REXMT, 0); 2840 tp->t_rtttime = 0; 2841 tcp_do_prr_ack(tp, th, &to, 2842 sack_changed, &maxseg); 2843 tp->t_flags |= TF_ACKNOW; 2844 (void) tcp_output(tp); 2845 } else { 2846 tcp_sack_partialack(tp, th, 2847 &maxseg); 2848 } 2849 } else { 2850 tcp_newreno_partial_ack(tp, th); 2851 } 2852 } else if (IN_CONGRECOVERY(tp->t_flags) && 2853 (V_tcp_do_prr)) { 2854 tp->sackhint.delivered_data = 2855 BYTES_THIS_ACK(tp, th); 2856 tp->snd_fack = th->th_ack; 2857 /* 2858 * During ECN cwnd reduction 2859 * always use PRR-SSRB 2860 */ 2861 tcp_do_prr_ack(tp, th, &to, SACK_CHANGE, 2862 &maxseg); 2863 (void) tcp_output(tp); 2864 } 2865 } 2866 /* 2867 * If we reach this point, ACK is not a duplicate, 2868 * i.e., it ACKs something we sent. 2869 */ 2870 if (tp->t_flags & TF_NEEDSYN) { 2871 /* 2872 * T/TCP: Connection was half-synchronized, and our 2873 * SYN has been ACK'd (so connection is now fully 2874 * synchronized). Go to non-starred state, 2875 * increment snd_una for ACK of SYN, and check if 2876 * we can do window scaling. 2877 */ 2878 tp->t_flags &= ~TF_NEEDSYN; 2879 tp->snd_una++; 2880 /* Do window scaling? */ 2881 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2882 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2883 tp->rcv_scale = tp->request_r_scale; 2884 /* Send window already scaled. */ 2885 } 2886 } 2887 2888 process_ACK: 2889 INP_WLOCK_ASSERT(inp); 2890 2891 /* 2892 * Adjust for the SYN bit in sequence space, 2893 * but don't account for it in cwnd calculations. 2894 * This is for the SYN_RECEIVED, non-simultaneous 2895 * SYN case. SYN_SENT and simultaneous SYN are 2896 * treated elsewhere. 2897 */ 2898 if (incforsyn) 2899 tp->snd_una++; 2900 acked = BYTES_THIS_ACK(tp, th); 2901 KASSERT(acked >= 0, ("%s: acked unexepectedly negative " 2902 "(tp->snd_una=%u, th->th_ack=%u, tp=%p, m=%p)", __func__, 2903 tp->snd_una, th->th_ack, tp, m)); 2904 TCPSTAT_ADD(tcps_rcvackpack, nsegs); 2905 TCPSTAT_ADD(tcps_rcvackbyte, acked); 2906 2907 /* 2908 * If we just performed our first retransmit, and the ACK 2909 * arrives within our recovery window, then it was a mistake 2910 * to do the retransmit in the first place. Recover our 2911 * original cwnd and ssthresh, and proceed to transmit where 2912 * we left off. 2913 */ 2914 if (tp->t_rxtshift == 1 && 2915 tp->t_flags & TF_PREVVALID && 2916 tp->t_badrxtwin != 0 && 2917 to.to_flags & TOF_TS && 2918 to.to_tsecr != 0 && 2919 TSTMP_LT(to.to_tsecr, tp->t_badrxtwin)) 2920 cc_cong_signal(tp, th, CC_RTO_ERR); 2921 2922 /* 2923 * If we have a timestamp reply, update smoothed 2924 * round trip time. If no timestamp is present but 2925 * transmit timer is running and timed sequence 2926 * number was acked, update smoothed round trip time. 2927 * Since we now have an rtt measurement, cancel the 2928 * timer backoff (cf., Phil Karn's retransmit alg.). 2929 * Recompute the initial retransmit timer. 2930 * 2931 * Some boxes send broken timestamp replies 2932 * during the SYN+ACK phase, ignore 2933 * timestamps of 0 or we could calculate a 2934 * huge RTT and blow up the retransmit timer. 2935 */ 2936 if ((to.to_flags & TOF_TS) != 0 && to.to_tsecr) { 2937 uint32_t t; 2938 2939 t = tcp_ts_getticks() - to.to_tsecr; 2940 if (!tp->t_rttlow || tp->t_rttlow > t) 2941 tp->t_rttlow = t; 2942 tcp_xmit_timer(tp, TCP_TS_TO_TICKS(t) + 1); 2943 } else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) { 2944 if (!tp->t_rttlow || tp->t_rttlow > ticks - tp->t_rtttime) 2945 tp->t_rttlow = ticks - tp->t_rtttime; 2946 tcp_xmit_timer(tp, ticks - tp->t_rtttime); 2947 } 2948 2949 SOCK_SENDBUF_LOCK(so); 2950 /* 2951 * Clear t_acktime if remote side has ACKd all data in the 2952 * socket buffer and FIN (if applicable). 2953 * Otherwise, update t_acktime if we received a sufficiently 2954 * large ACK. 2955 */ 2956 if ((tp->t_state <= TCPS_CLOSE_WAIT && 2957 acked == sbavail(&so->so_snd)) || 2958 acked > sbavail(&so->so_snd)) 2959 tp->t_acktime = 0; 2960 else if (acked > 1) 2961 tp->t_acktime = ticks; 2962 2963 /* 2964 * If all outstanding data is acked, stop retransmit 2965 * timer and remember to restart (more output or persist). 2966 * If there is more data to be acked, restart retransmit 2967 * timer, using current (possibly backed-off) value. 2968 */ 2969 if (th->th_ack == tp->snd_max) { 2970 tcp_timer_activate(tp, TT_REXMT, 0); 2971 needoutput = 1; 2972 } else if (!tcp_timer_active(tp, TT_PERSIST)) 2973 tcp_timer_activate(tp, TT_REXMT, TP_RXTCUR(tp)); 2974 2975 /* 2976 * If no data (only SYN) was ACK'd, 2977 * skip rest of ACK processing. 2978 */ 2979 if (acked == 0) { 2980 SOCK_SENDBUF_UNLOCK(so); 2981 goto step6; 2982 } 2983 2984 /* 2985 * Let the congestion control algorithm update congestion 2986 * control related information. This typically means increasing 2987 * the congestion window. 2988 */ 2989 cc_ack_received(tp, th, nsegs, CC_ACK); 2990 2991 if (acked > sbavail(&so->so_snd)) { 2992 if (tp->snd_wnd >= sbavail(&so->so_snd)) 2993 tp->snd_wnd -= sbavail(&so->so_snd); 2994 else 2995 tp->snd_wnd = 0; 2996 mfree = sbcut_locked(&so->so_snd, 2997 (int)sbavail(&so->so_snd)); 2998 ourfinisacked = 1; 2999 } else { 3000 mfree = sbcut_locked(&so->so_snd, acked); 3001 if (tp->snd_wnd >= (uint32_t) acked) 3002 tp->snd_wnd -= acked; 3003 else 3004 tp->snd_wnd = 0; 3005 ourfinisacked = 0; 3006 } 3007 /* NB: sowwakeup_locked() does an implicit unlock. */ 3008 sowwakeup_locked(so); 3009 m_freem(mfree); 3010 /* Detect una wraparound. */ 3011 if (!IN_RECOVERY(tp->t_flags) && 3012 SEQ_GT(tp->snd_una, tp->snd_recover) && 3013 SEQ_LEQ(th->th_ack, tp->snd_recover)) 3014 tp->snd_recover = th->th_ack - 1; 3015 tp->snd_una = th->th_ack; 3016 if (IN_RECOVERY(tp->t_flags) && 3017 SEQ_GEQ(th->th_ack, tp->snd_recover)) { 3018 cc_post_recovery(tp, th); 3019 } 3020 if (SEQ_GT(tp->snd_una, tp->snd_recover)) { 3021 tp->snd_recover = tp->snd_una; 3022 } 3023 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 3024 tp->snd_nxt = tp->snd_una; 3025 3026 switch (tp->t_state) { 3027 /* 3028 * In FIN_WAIT_1 STATE in addition to the processing 3029 * for the ESTABLISHED state if our FIN is now acknowledged 3030 * then enter FIN_WAIT_2. 3031 */ 3032 case TCPS_FIN_WAIT_1: 3033 if (ourfinisacked) { 3034 /* 3035 * If we can't receive any more 3036 * data, then closing user can proceed. 3037 * Starting the timer is contrary to the 3038 * specification, but if we don't get a FIN 3039 * we'll hang forever. 3040 */ 3041 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 3042 tcp_free_sackholes(tp); 3043 soisdisconnected(so); 3044 tcp_timer_activate(tp, TT_2MSL, 3045 (tcp_fast_finwait2_recycle ? 3046 tcp_finwait2_timeout : 3047 TP_MAXIDLE(tp))); 3048 } 3049 tcp_state_change(tp, TCPS_FIN_WAIT_2); 3050 } 3051 break; 3052 3053 /* 3054 * In CLOSING STATE in addition to the processing for 3055 * the ESTABLISHED state if the ACK acknowledges our FIN 3056 * then enter the TIME-WAIT state, otherwise ignore 3057 * the segment. 3058 */ 3059 case TCPS_CLOSING: 3060 if (ourfinisacked) { 3061 tcp_twstart(tp); 3062 m_freem(m); 3063 return; 3064 } 3065 break; 3066 3067 /* 3068 * In LAST_ACK, we may still be waiting for data to drain 3069 * and/or to be acked, as well as for the ack of our FIN. 3070 * If our FIN is now acknowledged, delete the TCB, 3071 * enter the closed state and return. 3072 */ 3073 case TCPS_LAST_ACK: 3074 if (ourfinisacked) { 3075 tp = tcp_close(tp); 3076 goto drop; 3077 } 3078 break; 3079 } 3080 } 3081 3082 step6: 3083 INP_WLOCK_ASSERT(inp); 3084 3085 /* 3086 * Update window information. 3087 * Don't look at window if no ACK: TAC's send garbage on first SYN. 3088 */ 3089 if ((thflags & TH_ACK) && 3090 (SEQ_LT(tp->snd_wl1, th->th_seq) || 3091 (tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) || 3092 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) { 3093 /* keep track of pure window updates */ 3094 if (no_data && tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) 3095 TCPSTAT_INC(tcps_rcvwinupd); 3096 tp->snd_wnd = tiwin; 3097 tp->snd_wl1 = th->th_seq; 3098 tp->snd_wl2 = th->th_ack; 3099 if (tp->snd_wnd > tp->max_sndwnd) 3100 tp->max_sndwnd = tp->snd_wnd; 3101 needoutput = 1; 3102 } 3103 3104 /* 3105 * Process segments with URG. 3106 */ 3107 if ((thflags & TH_URG) && th->th_urp && 3108 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3109 /* 3110 * This is a kludge, but if we receive and accept 3111 * random urgent pointers, we'll crash in 3112 * soreceive. It's hard to imagine someone 3113 * actually wanting to send this much urgent data. 3114 */ 3115 SOCK_RECVBUF_LOCK(so); 3116 if (th->th_urp + sbavail(&so->so_rcv) > sb_max) { 3117 th->th_urp = 0; /* XXX */ 3118 thflags &= ~TH_URG; /* XXX */ 3119 SOCK_RECVBUF_UNLOCK(so); /* XXX */ 3120 goto dodata; /* XXX */ 3121 } 3122 /* 3123 * If this segment advances the known urgent pointer, 3124 * then mark the data stream. This should not happen 3125 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 3126 * a FIN has been received from the remote side. 3127 * In these states we ignore the URG. 3128 * 3129 * According to RFC961 (Assigned Protocols), 3130 * the urgent pointer points to the last octet 3131 * of urgent data. We continue, however, 3132 * to consider it to indicate the first octet 3133 * of data past the urgent section as the original 3134 * spec states (in one of two places). 3135 */ 3136 if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) { 3137 tp->rcv_up = th->th_seq + th->th_urp; 3138 so->so_oobmark = sbavail(&so->so_rcv) + 3139 (tp->rcv_up - tp->rcv_nxt) - 1; 3140 if (so->so_oobmark == 0) 3141 so->so_rcv.sb_state |= SBS_RCVATMARK; 3142 sohasoutofband(so); 3143 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); 3144 } 3145 SOCK_RECVBUF_UNLOCK(so); 3146 /* 3147 * Remove out of band data so doesn't get presented to user. 3148 * This can happen independent of advancing the URG pointer, 3149 * but if two URG's are pending at once, some out-of-band 3150 * data may creep in... ick. 3151 */ 3152 if (th->th_urp <= (uint32_t)tlen && 3153 !(so->so_options & SO_OOBINLINE)) { 3154 /* hdr drop is delayed */ 3155 tcp_pulloutofband(so, th, m, drop_hdrlen); 3156 } 3157 } else { 3158 /* 3159 * If no out of band data is expected, 3160 * pull receive urgent pointer along 3161 * with the receive window. 3162 */ 3163 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) 3164 tp->rcv_up = tp->rcv_nxt; 3165 } 3166 dodata: /* XXX */ 3167 INP_WLOCK_ASSERT(inp); 3168 3169 /* 3170 * Process the segment text, merging it into the TCP sequencing queue, 3171 * and arranging for acknowledgment of receipt if necessary. 3172 * This process logically involves adjusting tp->rcv_wnd as data 3173 * is presented to the user (this happens in tcp_usrreq.c, 3174 * case PRU_RCVD). If a FIN has already been received on this 3175 * connection then we just ignore the text. 3176 */ 3177 tfo_syn = ((tp->t_state == TCPS_SYN_RECEIVED) && 3178 (tp->t_flags & TF_FASTOPEN)); 3179 if ((tlen || (thflags & TH_FIN) || (tfo_syn && tlen > 0)) && 3180 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3181 tcp_seq save_start = th->th_seq; 3182 tcp_seq save_rnxt = tp->rcv_nxt; 3183 int save_tlen = tlen; 3184 m_adj(m, drop_hdrlen); /* delayed header drop */ 3185 /* 3186 * Insert segment which includes th into TCP reassembly queue 3187 * with control block tp. Set thflags to whether reassembly now 3188 * includes a segment with FIN. This handles the common case 3189 * inline (segment is the next to be received on an established 3190 * connection, and the queue is empty), avoiding linkage into 3191 * and removal from the queue and repetition of various 3192 * conversions. 3193 * Set DELACK for segments received in order, but ack 3194 * immediately when segments are out of order (so 3195 * fast retransmit can work). 3196 */ 3197 if (th->th_seq == tp->rcv_nxt && 3198 SEGQ_EMPTY(tp) && 3199 (TCPS_HAVEESTABLISHED(tp->t_state) || 3200 tfo_syn)) { 3201 if (DELAY_ACK(tp, tlen) || tfo_syn) 3202 tp->t_flags |= TF_DELACK; 3203 else 3204 tp->t_flags |= TF_ACKNOW; 3205 tp->rcv_nxt += tlen; 3206 if (tlen && 3207 ((tp->t_flags2 & TF2_FBYTES_COMPLETE) == 0) && 3208 (tp->t_fbyte_in == 0)) { 3209 tp->t_fbyte_in = ticks; 3210 if (tp->t_fbyte_in == 0) 3211 tp->t_fbyte_in = 1; 3212 if (tp->t_fbyte_out && tp->t_fbyte_in) 3213 tp->t_flags2 |= TF2_FBYTES_COMPLETE; 3214 } 3215 thflags = tcp_get_flags(th) & TH_FIN; 3216 TCPSTAT_INC(tcps_rcvpack); 3217 TCPSTAT_ADD(tcps_rcvbyte, tlen); 3218 SOCK_RECVBUF_LOCK(so); 3219 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) 3220 m_freem(m); 3221 else 3222 sbappendstream_locked(&so->so_rcv, m, 0); 3223 tp->t_flags |= TF_WAKESOR; 3224 } else { 3225 /* 3226 * XXX: Due to the header drop above "th" is 3227 * theoretically invalid by now. Fortunately 3228 * m_adj() doesn't actually frees any mbufs 3229 * when trimming from the head. 3230 */ 3231 tcp_seq temp = save_start; 3232 3233 thflags = tcp_reass(tp, th, &temp, &tlen, m); 3234 tp->t_flags |= TF_ACKNOW; 3235 } 3236 if ((tp->t_flags & TF_SACK_PERMIT) && 3237 (save_tlen > 0) && 3238 TCPS_HAVEESTABLISHED(tp->t_state)) { 3239 if ((tlen == 0) && (SEQ_LT(save_start, save_rnxt))) { 3240 /* 3241 * DSACK actually handled in the fastpath 3242 * above. 3243 */ 3244 tcp_update_sack_list(tp, save_start, 3245 save_start + save_tlen); 3246 } else if ((tlen > 0) && SEQ_GT(tp->rcv_nxt, save_rnxt)) { 3247 if ((tp->rcv_numsacks >= 1) && 3248 (tp->sackblks[0].end == save_start)) { 3249 /* 3250 * Partial overlap, recorded at todrop 3251 * above. 3252 */ 3253 tcp_update_sack_list(tp, 3254 tp->sackblks[0].start, 3255 tp->sackblks[0].end); 3256 } else { 3257 tcp_update_dsack_list(tp, save_start, 3258 save_start + save_tlen); 3259 } 3260 } else if (tlen >= save_tlen) { 3261 /* Update of sackblks. */ 3262 tcp_update_dsack_list(tp, save_start, 3263 save_start + save_tlen); 3264 } else if (tlen > 0) { 3265 tcp_update_dsack_list(tp, save_start, 3266 save_start + tlen); 3267 } 3268 } 3269 tcp_handle_wakeup(tp); 3270 #if 0 3271 /* 3272 * Note the amount of data that peer has sent into 3273 * our window, in order to estimate the sender's 3274 * buffer size. 3275 * XXX: Unused. 3276 */ 3277 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt)) 3278 len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); 3279 else 3280 len = so->so_rcv.sb_hiwat; 3281 #endif 3282 } else { 3283 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 3284 if (tlen > 0) { 3285 if ((thflags & TH_FIN) != 0) { 3286 log(LOG_DEBUG, "%s; %s: %s: " 3287 "Received %d bytes of data and FIN " 3288 "after having received a FIN, " 3289 "just dropping both\n", 3290 s, __func__, 3291 tcpstates[tp->t_state], tlen); 3292 } else { 3293 log(LOG_DEBUG, "%s; %s: %s: " 3294 "Received %d bytes of data " 3295 "after having received a FIN, " 3296 "just dropping it\n", 3297 s, __func__, 3298 tcpstates[tp->t_state], tlen); 3299 } 3300 } else { 3301 if ((thflags & TH_FIN) != 0) { 3302 log(LOG_DEBUG, "%s; %s: %s: " 3303 "Received FIN " 3304 "after having received a FIN, " 3305 "just dropping it\n", 3306 s, __func__, 3307 tcpstates[tp->t_state]); 3308 } 3309 } 3310 free(s, M_TCPLOG); 3311 } 3312 m_freem(m); 3313 thflags &= ~TH_FIN; 3314 } 3315 3316 /* 3317 * If FIN is received ACK the FIN and let the user know 3318 * that the connection is closing. 3319 */ 3320 if (thflags & TH_FIN) { 3321 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3322 /* The socket upcall is handled by socantrcvmore. */ 3323 socantrcvmore(so); 3324 /* 3325 * If connection is half-synchronized 3326 * (ie NEEDSYN flag on) then delay ACK, 3327 * so it may be piggybacked when SYN is sent. 3328 * Otherwise, since we received a FIN then no 3329 * more input can be expected, send ACK now. 3330 */ 3331 if (tp->t_flags & TF_NEEDSYN) 3332 tp->t_flags |= TF_DELACK; 3333 else 3334 tp->t_flags |= TF_ACKNOW; 3335 tp->rcv_nxt++; 3336 } 3337 switch (tp->t_state) { 3338 /* 3339 * In SYN_RECEIVED and ESTABLISHED STATES 3340 * enter the CLOSE_WAIT state. 3341 */ 3342 case TCPS_SYN_RECEIVED: 3343 tp->t_starttime = ticks; 3344 /* FALLTHROUGH */ 3345 case TCPS_ESTABLISHED: 3346 tcp_state_change(tp, TCPS_CLOSE_WAIT); 3347 break; 3348 3349 /* 3350 * If still in FIN_WAIT_1 STATE FIN has not been acked so 3351 * enter the CLOSING state. 3352 */ 3353 case TCPS_FIN_WAIT_1: 3354 tcp_state_change(tp, TCPS_CLOSING); 3355 break; 3356 3357 /* 3358 * In FIN_WAIT_2 state enter the TIME_WAIT state, 3359 * starting the time-wait timer, turning off the other 3360 * standard timers. 3361 */ 3362 case TCPS_FIN_WAIT_2: 3363 tcp_twstart(tp); 3364 return; 3365 } 3366 } 3367 TCP_PROBE3(debug__input, tp, th, m); 3368 3369 /* 3370 * Return any desired output. 3371 */ 3372 if (needoutput || (tp->t_flags & TF_ACKNOW)) { 3373 (void) tcp_output(tp); 3374 } 3375 check_delack: 3376 INP_WLOCK_ASSERT(inp); 3377 3378 if (tp->t_flags & TF_DELACK) { 3379 tp->t_flags &= ~TF_DELACK; 3380 tcp_timer_activate(tp, TT_DELACK, tcp_delacktime); 3381 } 3382 INP_WUNLOCK(inp); 3383 return; 3384 3385 dropafterack: 3386 /* 3387 * Generate an ACK dropping incoming segment if it occupies 3388 * sequence space, where the ACK reflects our state. 3389 * 3390 * We can now skip the test for the RST flag since all 3391 * paths to this code happen after packets containing 3392 * RST have been dropped. 3393 * 3394 * In the SYN-RECEIVED state, don't send an ACK unless the 3395 * segment we received passes the SYN-RECEIVED ACK test. 3396 * If it fails send a RST. This breaks the loop in the 3397 * "LAND" DoS attack, and also prevents an ACK storm 3398 * between two listening ports that have been sent forged 3399 * SYN segments, each with the source address of the other. 3400 */ 3401 if (tp->t_state == TCPS_SYN_RECEIVED && (thflags & TH_ACK) && 3402 (SEQ_GT(tp->snd_una, th->th_ack) || 3403 SEQ_GT(th->th_ack, tp->snd_max)) ) { 3404 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 3405 goto dropwithreset; 3406 } 3407 TCP_PROBE3(debug__input, tp, th, m); 3408 tp->t_flags |= TF_ACKNOW; 3409 (void) tcp_output(tp); 3410 INP_WUNLOCK(inp); 3411 m_freem(m); 3412 return; 3413 3414 dropwithreset: 3415 tcp_dropwithreset(m, th, NULL, tlen); 3416 if (tp != NULL) { 3417 INP_WUNLOCK(inp); 3418 } 3419 return; 3420 3421 drop: 3422 /* 3423 * Drop space held by incoming segment and return. 3424 */ 3425 TCP_PROBE3(debug__input, tp, th, m); 3426 if (tp != NULL) { 3427 INP_WUNLOCK(inp); 3428 } 3429 m_freem(m); 3430 } 3431 3432 /* 3433 * Issue RST and make ACK acceptable to originator of segment. 3434 * The mbuf must still include the original packet header. 3435 * tp may be NULL. 3436 */ 3437 void 3438 tcp_dropwithreset(struct mbuf *m, struct tcphdr *th, struct tcpcb *tp, int tlen) 3439 { 3440 #ifdef INET 3441 struct ip *ip; 3442 #endif 3443 #ifdef INET6 3444 struct ip6_hdr *ip6; 3445 #endif 3446 3447 if (tp != NULL) { 3448 INP_LOCK_ASSERT(tptoinpcb(tp)); 3449 } 3450 3451 /* Don't bother if destination was broadcast/multicast. */ 3452 if ((tcp_get_flags(th) & TH_RST) || m->m_flags & (M_BCAST|M_MCAST)) 3453 goto drop; 3454 #ifdef INET6 3455 if (mtod(m, struct ip *)->ip_v == 6) { 3456 ip6 = mtod(m, struct ip6_hdr *); 3457 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 3458 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) 3459 goto drop; 3460 /* IPv6 anycast check is done at tcp6_input() */ 3461 } 3462 #endif 3463 #if defined(INET) && defined(INET6) 3464 else 3465 #endif 3466 #ifdef INET 3467 { 3468 ip = mtod(m, struct ip *); 3469 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 3470 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 3471 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || 3472 in_ifnet_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 3473 goto drop; 3474 } 3475 #endif 3476 3477 /* Perform bandwidth limiting. */ 3478 if (badport_bandlim(BANDLIM_TCP_RST) < 0) 3479 goto drop; 3480 3481 /* tcp_respond consumes the mbuf chain. */ 3482 if (tcp_get_flags(th) & TH_ACK) { 3483 tcp_respond(tp, mtod(m, void *), th, m, (tcp_seq)0, 3484 th->th_ack, TH_RST); 3485 } else { 3486 if (tcp_get_flags(th) & TH_SYN) 3487 tlen++; 3488 if (tcp_get_flags(th) & TH_FIN) 3489 tlen++; 3490 tcp_respond(tp, mtod(m, void *), th, m, th->th_seq+tlen, 3491 (tcp_seq)0, TH_RST|TH_ACK); 3492 } 3493 return; 3494 drop: 3495 m_freem(m); 3496 } 3497 3498 /* 3499 * Parse TCP options and place in tcpopt. 3500 */ 3501 void 3502 tcp_dooptions(struct tcpopt *to, u_char *cp, int cnt, int flags) 3503 { 3504 int opt, optlen; 3505 3506 to->to_flags = 0; 3507 for (; cnt > 0; cnt -= optlen, cp += optlen) { 3508 opt = cp[0]; 3509 if (opt == TCPOPT_EOL) 3510 break; 3511 if (opt == TCPOPT_NOP) 3512 optlen = 1; 3513 else { 3514 if (cnt < 2) 3515 break; 3516 optlen = cp[1]; 3517 if (optlen < 2 || optlen > cnt) 3518 break; 3519 } 3520 switch (opt) { 3521 case TCPOPT_MAXSEG: 3522 if (optlen != TCPOLEN_MAXSEG) 3523 continue; 3524 if (!(flags & TO_SYN)) 3525 continue; 3526 to->to_flags |= TOF_MSS; 3527 bcopy((char *)cp + 2, 3528 (char *)&to->to_mss, sizeof(to->to_mss)); 3529 to->to_mss = ntohs(to->to_mss); 3530 break; 3531 case TCPOPT_WINDOW: 3532 if (optlen != TCPOLEN_WINDOW) 3533 continue; 3534 if (!(flags & TO_SYN)) 3535 continue; 3536 to->to_flags |= TOF_SCALE; 3537 to->to_wscale = min(cp[2], TCP_MAX_WINSHIFT); 3538 break; 3539 case TCPOPT_TIMESTAMP: 3540 if (optlen != TCPOLEN_TIMESTAMP) 3541 continue; 3542 to->to_flags |= TOF_TS; 3543 bcopy((char *)cp + 2, 3544 (char *)&to->to_tsval, sizeof(to->to_tsval)); 3545 to->to_tsval = ntohl(to->to_tsval); 3546 bcopy((char *)cp + 6, 3547 (char *)&to->to_tsecr, sizeof(to->to_tsecr)); 3548 to->to_tsecr = ntohl(to->to_tsecr); 3549 break; 3550 case TCPOPT_SIGNATURE: 3551 /* 3552 * In order to reply to a host which has set the 3553 * TCP_SIGNATURE option in its initial SYN, we have 3554 * to record the fact that the option was observed 3555 * here for the syncache code to perform the correct 3556 * response. 3557 */ 3558 if (optlen != TCPOLEN_SIGNATURE) 3559 continue; 3560 to->to_flags |= TOF_SIGNATURE; 3561 to->to_signature = cp + 2; 3562 break; 3563 case TCPOPT_SACK_PERMITTED: 3564 if (optlen != TCPOLEN_SACK_PERMITTED) 3565 continue; 3566 if (!(flags & TO_SYN)) 3567 continue; 3568 if (!V_tcp_do_sack) 3569 continue; 3570 to->to_flags |= TOF_SACKPERM; 3571 break; 3572 case TCPOPT_SACK: 3573 if (optlen <= 2 || (optlen - 2) % TCPOLEN_SACK != 0) 3574 continue; 3575 if (flags & TO_SYN) 3576 continue; 3577 to->to_flags |= TOF_SACK; 3578 to->to_nsacks = (optlen - 2) / TCPOLEN_SACK; 3579 to->to_sacks = cp + 2; 3580 TCPSTAT_INC(tcps_sack_rcv_blocks); 3581 break; 3582 case TCPOPT_FAST_OPEN: 3583 /* 3584 * Cookie length validation is performed by the 3585 * server side cookie checking code or the client 3586 * side cookie cache update code. 3587 */ 3588 if (!(flags & TO_SYN)) 3589 continue; 3590 if (!V_tcp_fastopen_client_enable && 3591 !V_tcp_fastopen_server_enable) 3592 continue; 3593 to->to_flags |= TOF_FASTOPEN; 3594 to->to_tfo_len = optlen - 2; 3595 to->to_tfo_cookie = to->to_tfo_len ? cp + 2 : NULL; 3596 break; 3597 default: 3598 continue; 3599 } 3600 } 3601 } 3602 3603 /* 3604 * Pull out of band byte out of a segment so 3605 * it doesn't appear in the user's data queue. 3606 * It is still reflected in the segment length for 3607 * sequencing purposes. 3608 */ 3609 void 3610 tcp_pulloutofband(struct socket *so, struct tcphdr *th, struct mbuf *m, 3611 int off) 3612 { 3613 int cnt = off + th->th_urp - 1; 3614 3615 while (cnt >= 0) { 3616 if (m->m_len > cnt) { 3617 char *cp = mtod(m, caddr_t) + cnt; 3618 struct tcpcb *tp = sototcpcb(so); 3619 3620 INP_WLOCK_ASSERT(tptoinpcb(tp)); 3621 3622 tp->t_iobc = *cp; 3623 tp->t_oobflags |= TCPOOB_HAVEDATA; 3624 bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); 3625 m->m_len--; 3626 if (m->m_flags & M_PKTHDR) 3627 m->m_pkthdr.len--; 3628 return; 3629 } 3630 cnt -= m->m_len; 3631 m = m->m_next; 3632 if (m == NULL) 3633 break; 3634 } 3635 panic("tcp_pulloutofband"); 3636 } 3637 3638 /* 3639 * Collect new round-trip time estimate 3640 * and update averages and current timeout. 3641 */ 3642 void 3643 tcp_xmit_timer(struct tcpcb *tp, int rtt) 3644 { 3645 int delta; 3646 3647 INP_WLOCK_ASSERT(tptoinpcb(tp)); 3648 3649 TCPSTAT_INC(tcps_rttupdated); 3650 if (tp->t_rttupdated < UCHAR_MAX) 3651 tp->t_rttupdated++; 3652 #ifdef STATS 3653 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_RTT, 3654 imax(0, rtt * 1000 / hz)); 3655 #endif 3656 if ((tp->t_srtt != 0) && (tp->t_rxtshift <= TCP_RTT_INVALIDATE)) { 3657 /* 3658 * srtt is stored as fixed point with 5 bits after the 3659 * binary point (i.e., scaled by 8). The following magic 3660 * is equivalent to the smoothing algorithm in rfc793 with 3661 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed 3662 * point). Adjust rtt to origin 0. 3663 */ 3664 delta = ((rtt - 1) << TCP_DELTA_SHIFT) 3665 - (tp->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT)); 3666 3667 if ((tp->t_srtt += delta) <= 0) 3668 tp->t_srtt = 1; 3669 3670 /* 3671 * We accumulate a smoothed rtt variance (actually, a 3672 * smoothed mean difference), then set the retransmit 3673 * timer to smoothed rtt + 4 times the smoothed variance. 3674 * rttvar is stored as fixed point with 4 bits after the 3675 * binary point (scaled by 16). The following is 3676 * equivalent to rfc793 smoothing with an alpha of .75 3677 * (rttvar = rttvar*3/4 + |delta| / 4). This replaces 3678 * rfc793's wired-in beta. 3679 */ 3680 if (delta < 0) 3681 delta = -delta; 3682 delta -= tp->t_rttvar >> (TCP_RTTVAR_SHIFT - TCP_DELTA_SHIFT); 3683 if ((tp->t_rttvar += delta) <= 0) 3684 tp->t_rttvar = 1; 3685 } else { 3686 /* 3687 * No rtt measurement yet - use the unsmoothed rtt. 3688 * Set the variance to half the rtt (so our first 3689 * retransmit happens at 3*rtt). 3690 */ 3691 tp->t_srtt = rtt << TCP_RTT_SHIFT; 3692 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1); 3693 } 3694 tp->t_rtttime = 0; 3695 tp->t_rxtshift = 0; 3696 3697 /* 3698 * the retransmit should happen at rtt + 4 * rttvar. 3699 * Because of the way we do the smoothing, srtt and rttvar 3700 * will each average +1/2 tick of bias. When we compute 3701 * the retransmit timer, we want 1/2 tick of rounding and 3702 * 1 extra tick because of +-1/2 tick uncertainty in the 3703 * firing of the timer. The bias will give us exactly the 3704 * 1.5 tick we need. But, because the bias is 3705 * statistical, we have to test that we don't drop below 3706 * the minimum feasible timer (which is 2 ticks). 3707 */ 3708 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), 3709 max(tp->t_rttmin, rtt + 2), tcp_rexmit_max); 3710 3711 /* 3712 * We received an ack for a packet that wasn't retransmitted; 3713 * it is probably safe to discard any error indications we've 3714 * received recently. This isn't quite right, but close enough 3715 * for now (a route might have failed after we sent a segment, 3716 * and the return path might not be symmetrical). 3717 */ 3718 tp->t_softerror = 0; 3719 } 3720 3721 /* 3722 * Determine a reasonable value for maxseg size. 3723 * If the route is known, check route for mtu. 3724 * If none, use an mss that can be handled on the outgoing interface 3725 * without forcing IP to fragment. If no route is found, route has no mtu, 3726 * or the destination isn't local, use a default, hopefully conservative 3727 * size (usually 512 or the default IP max size, but no more than the mtu 3728 * of the interface), as we can't discover anything about intervening 3729 * gateways or networks. We also initialize the congestion/slow start 3730 * window to be a single segment if the destination isn't local. 3731 * While looking at the routing entry, we also initialize other path-dependent 3732 * parameters from pre-set or cached values in the routing entry. 3733 * 3734 * NOTE that resulting t_maxseg doesn't include space for TCP options or 3735 * IP options, e.g. IPSEC data, since length of this data may vary, and 3736 * thus it is calculated for every segment separately in tcp_output(). 3737 * 3738 * NOTE that this routine is only called when we process an incoming 3739 * segment, or an ICMP need fragmentation datagram. Outgoing SYN/ACK MSS 3740 * settings are handled in tcp_mssopt(). 3741 */ 3742 void 3743 tcp_mss_update(struct tcpcb *tp, int offer, int mtuoffer, 3744 struct hc_metrics_lite *metricptr, struct tcp_ifcap *cap) 3745 { 3746 int mss = 0; 3747 uint32_t maxmtu = 0; 3748 struct inpcb *inp = tptoinpcb(tp); 3749 struct hc_metrics_lite metrics; 3750 #ifdef INET6 3751 int isipv6 = ((inp->inp_vflag & INP_IPV6) != 0) ? 1 : 0; 3752 size_t min_protoh = isipv6 ? 3753 sizeof (struct ip6_hdr) + sizeof (struct tcphdr) : 3754 sizeof (struct tcpiphdr); 3755 #else 3756 size_t min_protoh = sizeof(struct tcpiphdr); 3757 #endif 3758 3759 INP_WLOCK_ASSERT(inp); 3760 3761 if (tp->t_port) 3762 min_protoh += V_tcp_udp_tunneling_overhead; 3763 if (mtuoffer != -1) { 3764 KASSERT(offer == -1, ("%s: conflict", __func__)); 3765 offer = mtuoffer - min_protoh; 3766 } 3767 3768 /* Initialize. */ 3769 #ifdef INET6 3770 if (isipv6) { 3771 maxmtu = tcp_maxmtu6(&inp->inp_inc, cap); 3772 tp->t_maxseg = V_tcp_v6mssdflt; 3773 } 3774 #endif 3775 #if defined(INET) && defined(INET6) 3776 else 3777 #endif 3778 #ifdef INET 3779 { 3780 maxmtu = tcp_maxmtu(&inp->inp_inc, cap); 3781 tp->t_maxseg = V_tcp_mssdflt; 3782 } 3783 #endif 3784 3785 /* 3786 * No route to sender, stay with default mss and return. 3787 */ 3788 if (maxmtu == 0) { 3789 /* 3790 * In case we return early we need to initialize metrics 3791 * to a defined state as tcp_hc_get() would do for us 3792 * if there was no cache hit. 3793 */ 3794 if (metricptr != NULL) 3795 bzero(metricptr, sizeof(struct hc_metrics_lite)); 3796 return; 3797 } 3798 3799 /* What have we got? */ 3800 switch (offer) { 3801 case 0: 3802 /* 3803 * Offer == 0 means that there was no MSS on the SYN 3804 * segment, in this case we use tcp_mssdflt as 3805 * already assigned to t_maxseg above. 3806 */ 3807 offer = tp->t_maxseg; 3808 break; 3809 3810 case -1: 3811 /* 3812 * Offer == -1 means that we didn't receive SYN yet. 3813 */ 3814 /* FALLTHROUGH */ 3815 3816 default: 3817 /* 3818 * Prevent DoS attack with too small MSS. Round up 3819 * to at least minmss. 3820 */ 3821 offer = max(offer, V_tcp_minmss); 3822 } 3823 3824 if (metricptr == NULL) 3825 metricptr = &metrics; 3826 tcp_hc_get(&inp->inp_inc, metricptr); 3827 3828 /* 3829 * If there's a discovered mtu in tcp hostcache, use it. 3830 * Else, use the link mtu. 3831 */ 3832 if (metricptr->hc_mtu) 3833 mss = min(metricptr->hc_mtu, maxmtu) - min_protoh; 3834 else { 3835 #ifdef INET6 3836 if (isipv6) { 3837 mss = maxmtu - min_protoh; 3838 if (!V_path_mtu_discovery && 3839 !in6_localaddr(&inp->in6p_faddr)) 3840 mss = min(mss, V_tcp_v6mssdflt); 3841 } 3842 #endif 3843 #if defined(INET) && defined(INET6) 3844 else 3845 #endif 3846 #ifdef INET 3847 { 3848 mss = maxmtu - min_protoh; 3849 if (!V_path_mtu_discovery && 3850 !in_localaddr(inp->inp_faddr)) 3851 mss = min(mss, V_tcp_mssdflt); 3852 } 3853 #endif 3854 /* 3855 * XXX - The above conditional (mss = maxmtu - min_protoh) 3856 * probably violates the TCP spec. 3857 * The problem is that, since we don't know the 3858 * other end's MSS, we are supposed to use a conservative 3859 * default. But, if we do that, then MTU discovery will 3860 * never actually take place, because the conservative 3861 * default is much less than the MTUs typically seen 3862 * on the Internet today. For the moment, we'll sweep 3863 * this under the carpet. 3864 * 3865 * The conservative default might not actually be a problem 3866 * if the only case this occurs is when sending an initial 3867 * SYN with options and data to a host we've never talked 3868 * to before. Then, they will reply with an MSS value which 3869 * will get recorded and the new parameters should get 3870 * recomputed. For Further Study. 3871 */ 3872 } 3873 mss = min(mss, offer); 3874 3875 /* 3876 * Sanity check: make sure that maxseg will be large 3877 * enough to allow some data on segments even if the 3878 * all the option space is used (40bytes). Otherwise 3879 * funny things may happen in tcp_output. 3880 * 3881 * XXXGL: shouldn't we reserve space for IP/IPv6 options? 3882 */ 3883 mss = max(mss, 64); 3884 3885 tp->t_maxseg = mss; 3886 if (tp->t_maxseg < V_tcp_mssdflt) { 3887 /* 3888 * The MSS is so small we should not process incoming 3889 * SACK's since we are subject to attack in such a 3890 * case. 3891 */ 3892 tp->t_flags2 |= TF2_PROC_SACK_PROHIBIT; 3893 } else { 3894 tp->t_flags2 &= ~TF2_PROC_SACK_PROHIBIT; 3895 } 3896 3897 } 3898 3899 void 3900 tcp_mss(struct tcpcb *tp, int offer) 3901 { 3902 int mss; 3903 uint32_t bufsize; 3904 struct inpcb *inp = tptoinpcb(tp); 3905 struct socket *so; 3906 struct hc_metrics_lite metrics; 3907 struct tcp_ifcap cap; 3908 3909 KASSERT(tp != NULL, ("%s: tp == NULL", __func__)); 3910 3911 bzero(&cap, sizeof(cap)); 3912 tcp_mss_update(tp, offer, -1, &metrics, &cap); 3913 3914 mss = tp->t_maxseg; 3915 3916 /* 3917 * If there's a pipesize, change the socket buffer to that size, 3918 * don't change if sb_hiwat is different than default (then it 3919 * has been changed on purpose with setsockopt). 3920 * Make the socket buffers an integral number of mss units; 3921 * if the mss is larger than the socket buffer, decrease the mss. 3922 */ 3923 so = inp->inp_socket; 3924 SOCK_SENDBUF_LOCK(so); 3925 if ((so->so_snd.sb_hiwat == V_tcp_sendspace) && metrics.hc_sendpipe) 3926 bufsize = metrics.hc_sendpipe; 3927 else 3928 bufsize = so->so_snd.sb_hiwat; 3929 if (bufsize < mss) 3930 mss = bufsize; 3931 else { 3932 bufsize = roundup(bufsize, mss); 3933 if (bufsize > sb_max) 3934 bufsize = sb_max; 3935 if (bufsize > so->so_snd.sb_hiwat) 3936 (void)sbreserve_locked(so, SO_SND, bufsize, NULL); 3937 } 3938 SOCK_SENDBUF_UNLOCK(so); 3939 /* 3940 * Sanity check: make sure that maxseg will be large 3941 * enough to allow some data on segments even if the 3942 * all the option space is used (40bytes). Otherwise 3943 * funny things may happen in tcp_output. 3944 * 3945 * XXXGL: shouldn't we reserve space for IP/IPv6 options? 3946 */ 3947 tp->t_maxseg = max(mss, 64); 3948 if (tp->t_maxseg < V_tcp_mssdflt) { 3949 /* 3950 * The MSS is so small we should not process incoming 3951 * SACK's since we are subject to attack in such a 3952 * case. 3953 */ 3954 tp->t_flags2 |= TF2_PROC_SACK_PROHIBIT; 3955 } else { 3956 tp->t_flags2 &= ~TF2_PROC_SACK_PROHIBIT; 3957 } 3958 3959 SOCK_RECVBUF_LOCK(so); 3960 if ((so->so_rcv.sb_hiwat == V_tcp_recvspace) && metrics.hc_recvpipe) 3961 bufsize = metrics.hc_recvpipe; 3962 else 3963 bufsize = so->so_rcv.sb_hiwat; 3964 if (bufsize > mss) { 3965 bufsize = roundup(bufsize, mss); 3966 if (bufsize > sb_max) 3967 bufsize = sb_max; 3968 if (bufsize > so->so_rcv.sb_hiwat) 3969 (void)sbreserve_locked(so, SO_RCV, bufsize, NULL); 3970 } 3971 SOCK_RECVBUF_UNLOCK(so); 3972 3973 /* Check the interface for TSO capabilities. */ 3974 if (cap.ifcap & CSUM_TSO) { 3975 tp->t_flags |= TF_TSO; 3976 tp->t_tsomax = cap.tsomax; 3977 tp->t_tsomaxsegcount = cap.tsomaxsegcount; 3978 tp->t_tsomaxsegsize = cap.tsomaxsegsize; 3979 if (cap.ipsec_tso) 3980 tp->t_flags2 |= TF2_IPSEC_TSO; 3981 } 3982 } 3983 3984 /* 3985 * Determine the MSS option to send on an outgoing SYN. 3986 */ 3987 int 3988 tcp_mssopt(struct in_conninfo *inc) 3989 { 3990 int mss = 0; 3991 uint32_t thcmtu = 0; 3992 uint32_t maxmtu = 0; 3993 size_t min_protoh; 3994 3995 KASSERT(inc != NULL, ("tcp_mssopt with NULL in_conninfo pointer")); 3996 3997 #ifdef INET6 3998 if (inc->inc_flags & INC_ISIPV6) { 3999 mss = V_tcp_v6mssdflt; 4000 maxmtu = tcp_maxmtu6(inc, NULL); 4001 min_protoh = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 4002 } 4003 #endif 4004 #if defined(INET) && defined(INET6) 4005 else 4006 #endif 4007 #ifdef INET 4008 { 4009 mss = V_tcp_mssdflt; 4010 maxmtu = tcp_maxmtu(inc, NULL); 4011 min_protoh = sizeof(struct tcpiphdr); 4012 } 4013 #endif 4014 #if defined(INET6) || defined(INET) 4015 thcmtu = tcp_hc_getmtu(inc); /* IPv4 and IPv6 */ 4016 #endif 4017 4018 if (maxmtu && thcmtu) 4019 mss = min(maxmtu, thcmtu) - min_protoh; 4020 else if (maxmtu || thcmtu) 4021 mss = max(maxmtu, thcmtu) - min_protoh; 4022 4023 return (mss); 4024 } 4025 4026 void 4027 tcp_do_prr_ack(struct tcpcb *tp, struct tcphdr *th, struct tcpopt *to, 4028 sackstatus_t sack_changed, u_int *maxsegp) 4029 { 4030 int snd_cnt = 0, limit = 0, del_data = 0, pipe = 0; 4031 u_int maxseg; 4032 4033 INP_WLOCK_ASSERT(tptoinpcb(tp)); 4034 4035 if (*maxsegp == 0) { 4036 *maxsegp = tcp_maxseg(tp); 4037 } 4038 maxseg = *maxsegp; 4039 /* 4040 * Compute the amount of data that this ACK is indicating 4041 * (del_data) and an estimate of how many bytes are in the 4042 * network. 4043 */ 4044 if (tcp_is_sack_recovery(tp, to) || 4045 (IN_CONGRECOVERY(tp->t_flags) && 4046 !IN_FASTRECOVERY(tp->t_flags))) { 4047 del_data = tp->sackhint.delivered_data; 4048 pipe = tcp_compute_pipe(tp); 4049 } else { 4050 if (tp->sackhint.prr_delivered < (tcprexmtthresh * maxseg + 4051 tp->snd_recover - tp->snd_una)) { 4052 del_data = maxseg; 4053 } 4054 pipe = imax(0, tp->snd_max - tp->snd_una - 4055 imin(INT_MAX / 65536, tp->t_dupacks) * maxseg); 4056 } 4057 tp->sackhint.prr_delivered += del_data; 4058 /* 4059 * Proportional Rate Reduction 4060 */ 4061 if (pipe >= tp->snd_ssthresh) { 4062 if (tp->sackhint.recover_fs == 0) 4063 tp->sackhint.recover_fs = 4064 imax(1, tp->snd_nxt - tp->snd_una); 4065 snd_cnt = howmany((long)tp->sackhint.prr_delivered * 4066 tp->snd_ssthresh, tp->sackhint.recover_fs) - 4067 tp->sackhint.prr_out + maxseg - 1; 4068 } else { 4069 /* 4070 * PRR 6937bis heuristic: 4071 * - A partial ack without SACK block beneath snd_recover 4072 * indicates further loss. 4073 * - An SACK scoreboard update adding a new hole indicates 4074 * further loss, so be conservative and send at most one 4075 * segment. 4076 * - Prevent ACK splitting attacks, by being conservative 4077 * when no new data is acked. 4078 */ 4079 if ((sack_changed == SACK_NEWLOSS) || (del_data == 0)) { 4080 limit = tp->sackhint.prr_delivered - 4081 tp->sackhint.prr_out; 4082 } else { 4083 limit = imax(tp->sackhint.prr_delivered - 4084 tp->sackhint.prr_out, del_data) + 4085 maxseg; 4086 } 4087 snd_cnt = imin((tp->snd_ssthresh - pipe), limit); 4088 } 4089 snd_cnt = imax(snd_cnt, 0) / maxseg; 4090 /* 4091 * Send snd_cnt new data into the network in response to this ack. 4092 * If there is going to be a SACK retransmission, adjust snd_cwnd 4093 * accordingly. 4094 */ 4095 if (IN_FASTRECOVERY(tp->t_flags)) { 4096 if (tcp_is_sack_recovery(tp, to)) { 4097 tp->snd_cwnd = pipe - del_data + (snd_cnt * maxseg); 4098 } else { 4099 tp->snd_cwnd = (tp->snd_max - tp->snd_una) + 4100 (snd_cnt * maxseg); 4101 } 4102 } else if (IN_CONGRECOVERY(tp->t_flags)) { 4103 tp->snd_cwnd = pipe - del_data + (snd_cnt * maxseg); 4104 } 4105 tp->snd_cwnd = imax(maxseg, tp->snd_cwnd); 4106 } 4107 4108 /* 4109 * On a partial ack arrives, force the retransmission of the 4110 * next unacknowledged segment. Do not clear tp->t_dupacks. 4111 * By setting snd_nxt to ti_ack, this forces retransmission timer to 4112 * be started again. 4113 */ 4114 void 4115 tcp_newreno_partial_ack(struct tcpcb *tp, struct tcphdr *th) 4116 { 4117 tcp_seq onxt = tp->snd_nxt; 4118 uint32_t ocwnd = tp->snd_cwnd; 4119 u_int maxseg = tcp_maxseg(tp); 4120 4121 INP_WLOCK_ASSERT(tptoinpcb(tp)); 4122 4123 tcp_timer_activate(tp, TT_REXMT, 0); 4124 tp->t_rtttime = 0; 4125 if (IN_FASTRECOVERY(tp->t_flags)) { 4126 tp->snd_nxt = th->th_ack; 4127 /* 4128 * Set snd_cwnd to one segment beyond acknowledged offset. 4129 * (tp->snd_una has not yet been updated when this function is called.) 4130 */ 4131 tp->snd_cwnd = maxseg + BYTES_THIS_ACK(tp, th); 4132 tp->t_flags |= TF_ACKNOW; 4133 (void) tcp_output(tp); 4134 tp->snd_cwnd = ocwnd; 4135 if (SEQ_GT(onxt, tp->snd_nxt)) 4136 tp->snd_nxt = onxt; 4137 } 4138 /* 4139 * Partial window deflation. Relies on fact that tp->snd_una 4140 * not updated yet. 4141 */ 4142 if (tp->snd_cwnd > BYTES_THIS_ACK(tp, th)) 4143 tp->snd_cwnd -= BYTES_THIS_ACK(tp, th); 4144 else 4145 tp->snd_cwnd = 0; 4146 tp->snd_cwnd += maxseg; 4147 } 4148 4149 int 4150 tcp_compute_pipe(struct tcpcb *tp) 4151 { 4152 int pipe; 4153 4154 if (tp->t_fb->tfb_compute_pipe != NULL) { 4155 pipe = (*tp->t_fb->tfb_compute_pipe)(tp); 4156 } else if (V_tcp_do_newsack) { 4157 pipe = tp->snd_max - tp->snd_una + 4158 tp->sackhint.sack_bytes_rexmit - 4159 tp->sackhint.sacked_bytes - 4160 tp->sackhint.lost_bytes; 4161 } else { 4162 pipe = tp->snd_nxt - tp->snd_fack + tp->sackhint.sack_bytes_rexmit; 4163 } 4164 return (imax(pipe, 0)); 4165 } 4166 4167 uint32_t 4168 tcp_compute_initwnd(uint32_t maxseg) 4169 { 4170 /* 4171 * Calculate the Initial Window, also used as Restart Window 4172 * 4173 * RFC5681 Section 3.1 specifies the default conservative values. 4174 * RFC3390 specifies slightly more aggressive values. 4175 * RFC6928 increases it to ten segments. 4176 * Support for user specified value for initial flight size. 4177 */ 4178 if (V_tcp_initcwnd_segments) 4179 return min(V_tcp_initcwnd_segments * maxseg, 4180 max(2 * maxseg, V_tcp_initcwnd_segments * 1460)); 4181 else if (V_tcp_do_rfc3390) 4182 return min(4 * maxseg, max(2 * maxseg, 4380)); 4183 else { 4184 /* Per RFC5681 Section 3.1 */ 4185 if (maxseg > 2190) 4186 return (2 * maxseg); 4187 else if (maxseg > 1095) 4188 return (3 * maxseg); 4189 else 4190 return (4 * maxseg); 4191 } 4192 } 4193