tcp_input.c revision 1.334
1 /* $NetBSD: tcp_input.c,v 1.334 2014/08/08 03:05:45 rtr Exp $ */ 2 3 /* 4 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the project nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 /* 33 * @(#)COPYRIGHT 1.1 (NRL) 17 January 1995 34 * 35 * NRL grants permission for redistribution and use in source and binary 36 * forms, with or without modification, of the software and documentation 37 * created at NRL provided that the following conditions are met: 38 * 39 * 1. Redistributions of source code must retain the above copyright 40 * notice, this list of conditions and the following disclaimer. 41 * 2. Redistributions in binary form must reproduce the above copyright 42 * notice, this list of conditions and the following disclaimer in the 43 * documentation and/or other materials provided with the distribution. 44 * 3. All advertising materials mentioning features or use of this software 45 * must display the following acknowledgements: 46 * This product includes software developed by the University of 47 * California, Berkeley and its contributors. 48 * This product includes software developed at the Information 49 * Technology Division, US Naval Research Laboratory. 50 * 4. Neither the name of the NRL nor the names of its contributors 51 * may be used to endorse or promote products derived from this software 52 * without specific prior written permission. 53 * 54 * THE SOFTWARE PROVIDED BY NRL IS PROVIDED BY NRL AND CONTRIBUTORS ``AS 55 * IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 56 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A 57 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL NRL OR 58 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 59 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 60 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 61 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 62 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 63 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 64 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 65 * 66 * The views and conclusions contained in the software and documentation 67 * are those of the authors and should not be interpreted as representing 68 * official policies, either expressed or implied, of the US Naval 69 * Research Laboratory (NRL). 70 */ 71 72 /*- 73 * Copyright (c) 1997, 1998, 1999, 2001, 2005, 2006, 74 * 2011 The NetBSD Foundation, Inc. 75 * All rights reserved. 76 * 77 * This code is derived from software contributed to The NetBSD Foundation 78 * by Coyote Point Systems, Inc. 79 * This code is derived from software contributed to The NetBSD Foundation 80 * by Jason R. Thorpe and Kevin M. Lahey of the Numerical Aerospace Simulation 81 * Facility, NASA Ames Research Center. 82 * This code is derived from software contributed to The NetBSD Foundation 83 * by Charles M. Hannum. 84 * This code is derived from software contributed to The NetBSD Foundation 85 * by Rui Paulo. 86 * 87 * Redistribution and use in source and binary forms, with or without 88 * modification, are permitted provided that the following conditions 89 * are met: 90 * 1. Redistributions of source code must retain the above copyright 91 * notice, this list of conditions and the following disclaimer. 92 * 2. Redistributions in binary form must reproduce the above copyright 93 * notice, this list of conditions and the following disclaimer in the 94 * documentation and/or other materials provided with the distribution. 95 * 96 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 97 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 98 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 99 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 100 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 101 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 102 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 103 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 104 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 105 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 106 * POSSIBILITY OF SUCH DAMAGE. 107 */ 108 109 /* 110 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995 111 * The Regents of the University of California. All rights reserved. 112 * 113 * Redistribution and use in source and binary forms, with or without 114 * modification, are permitted provided that the following conditions 115 * are met: 116 * 1. Redistributions of source code must retain the above copyright 117 * notice, this list of conditions and the following disclaimer. 118 * 2. Redistributions in binary form must reproduce the above copyright 119 * notice, this list of conditions and the following disclaimer in the 120 * documentation and/or other materials provided with the distribution. 121 * 3. Neither the name of the University nor the names of its contributors 122 * may be used to endorse or promote products derived from this software 123 * without specific prior written permission. 124 * 125 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 126 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 127 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 128 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 129 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 130 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 131 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 132 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 133 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 134 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 135 * SUCH DAMAGE. 136 * 137 * @(#)tcp_input.c 8.12 (Berkeley) 5/24/95 138 */ 139 140 /* 141 * TODO list for SYN cache stuff: 142 * 143 * Find room for a "state" field, which is needed to keep a 144 * compressed state for TIME_WAIT TCBs. It's been noted already 145 * that this is fairly important for very high-volume web and 146 * mail servers, which use a large number of short-lived 147 * connections. 148 */ 149 150 #include <sys/cdefs.h> 151 __KERNEL_RCSID(0, "$NetBSD: tcp_input.c,v 1.334 2014/08/08 03:05:45 rtr Exp $"); 152 153 #include "opt_inet.h" 154 #include "opt_ipsec.h" 155 #include "opt_inet_csum.h" 156 #include "opt_tcp_debug.h" 157 158 #include <sys/param.h> 159 #include <sys/systm.h> 160 #include <sys/malloc.h> 161 #include <sys/mbuf.h> 162 #include <sys/protosw.h> 163 #include <sys/socket.h> 164 #include <sys/socketvar.h> 165 #include <sys/errno.h> 166 #include <sys/syslog.h> 167 #include <sys/pool.h> 168 #include <sys/domain.h> 169 #include <sys/kernel.h> 170 #ifdef TCP_SIGNATURE 171 #include <sys/md5.h> 172 #endif 173 #include <sys/lwp.h> /* for lwp0 */ 174 #include <sys/cprng.h> 175 176 #include <net/if.h> 177 #include <net/route.h> 178 #include <net/if_types.h> 179 180 #include <netinet/in.h> 181 #include <netinet/in_systm.h> 182 #include <netinet/ip.h> 183 #include <netinet/in_pcb.h> 184 #include <netinet/in_var.h> 185 #include <netinet/ip_var.h> 186 #include <netinet/in_offload.h> 187 188 #ifdef INET6 189 #ifndef INET 190 #include <netinet/in.h> 191 #endif 192 #include <netinet/ip6.h> 193 #include <netinet6/ip6_var.h> 194 #include <netinet6/in6_pcb.h> 195 #include <netinet6/ip6_var.h> 196 #include <netinet6/in6_var.h> 197 #include <netinet/icmp6.h> 198 #include <netinet6/nd6.h> 199 #ifdef TCP_SIGNATURE 200 #include <netinet6/scope6_var.h> 201 #endif 202 #endif 203 204 #ifndef INET6 205 /* always need ip6.h for IP6_EXTHDR_GET */ 206 #include <netinet/ip6.h> 207 #endif 208 209 #include <netinet/tcp.h> 210 #include <netinet/tcp_fsm.h> 211 #include <netinet/tcp_seq.h> 212 #include <netinet/tcp_timer.h> 213 #include <netinet/tcp_var.h> 214 #include <netinet/tcp_private.h> 215 #include <netinet/tcpip.h> 216 #include <netinet/tcp_congctl.h> 217 #include <netinet/tcp_debug.h> 218 219 #ifdef INET6 220 #include "faith.h" 221 #if defined(NFAITH) && NFAITH > 0 222 #include <net/if_faith.h> 223 #endif 224 #endif /* INET6 */ 225 226 #ifdef IPSEC 227 #include <netipsec/ipsec.h> 228 #include <netipsec/ipsec_var.h> 229 #include <netipsec/ipsec_private.h> 230 #include <netipsec/key.h> 231 #ifdef INET6 232 #include <netipsec/ipsec6.h> 233 #endif 234 #endif /* IPSEC*/ 235 236 #include <netinet/tcp_vtw.h> 237 238 int tcprexmtthresh = 3; 239 int tcp_log_refused; 240 241 int tcp_do_autorcvbuf = 1; 242 int tcp_autorcvbuf_inc = 16 * 1024; 243 int tcp_autorcvbuf_max = 256 * 1024; 244 int tcp_msl = (TCPTV_MSL / PR_SLOWHZ); 245 246 static int tcp_rst_ppslim_count = 0; 247 static struct timeval tcp_rst_ppslim_last; 248 static int tcp_ackdrop_ppslim_count = 0; 249 static struct timeval tcp_ackdrop_ppslim_last; 250 251 #define TCP_PAWS_IDLE (24U * 24 * 60 * 60 * PR_SLOWHZ) 252 253 /* for modulo comparisons of timestamps */ 254 #define TSTMP_LT(a,b) ((int)((a)-(b)) < 0) 255 #define TSTMP_GEQ(a,b) ((int)((a)-(b)) >= 0) 256 257 /* 258 * Neighbor Discovery, Neighbor Unreachability Detection Upper layer hint. 259 */ 260 #ifdef INET6 261 static inline void 262 nd6_hint(struct tcpcb *tp) 263 { 264 struct rtentry *rt; 265 266 if (tp != NULL && tp->t_in6pcb != NULL && tp->t_family == AF_INET6 && 267 (rt = rtcache_validate(&tp->t_in6pcb->in6p_route)) != NULL) 268 nd6_nud_hint(rt, NULL, 0); 269 } 270 #else 271 static inline void 272 nd6_hint(struct tcpcb *tp) 273 { 274 } 275 #endif 276 277 /* 278 * Compute ACK transmission behavior. Delay the ACK unless 279 * we have already delayed an ACK (must send an ACK every two segments). 280 * We also ACK immediately if we received a PUSH and the ACK-on-PUSH 281 * option is enabled. 282 */ 283 static void 284 tcp_setup_ack(struct tcpcb *tp, const struct tcphdr *th) 285 { 286 287 if (tp->t_flags & TF_DELACK || 288 (tcp_ack_on_push && th->th_flags & TH_PUSH)) 289 tp->t_flags |= TF_ACKNOW; 290 else 291 TCP_SET_DELACK(tp); 292 } 293 294 static void 295 icmp_check(struct tcpcb *tp, const struct tcphdr *th, int acked) 296 { 297 298 /* 299 * If we had a pending ICMP message that refers to data that have 300 * just been acknowledged, disregard the recorded ICMP message. 301 */ 302 if ((tp->t_flags & TF_PMTUD_PEND) && 303 SEQ_GT(th->th_ack, tp->t_pmtud_th_seq)) 304 tp->t_flags &= ~TF_PMTUD_PEND; 305 306 /* 307 * Keep track of the largest chunk of data 308 * acknowledged since last PMTU update 309 */ 310 if (tp->t_pmtud_mss_acked < acked) 311 tp->t_pmtud_mss_acked = acked; 312 } 313 314 /* 315 * Convert TCP protocol fields to host order for easier processing. 316 */ 317 static void 318 tcp_fields_to_host(struct tcphdr *th) 319 { 320 321 NTOHL(th->th_seq); 322 NTOHL(th->th_ack); 323 NTOHS(th->th_win); 324 NTOHS(th->th_urp); 325 } 326 327 /* 328 * ... and reverse the above. 329 */ 330 static void 331 tcp_fields_to_net(struct tcphdr *th) 332 { 333 334 HTONL(th->th_seq); 335 HTONL(th->th_ack); 336 HTONS(th->th_win); 337 HTONS(th->th_urp); 338 } 339 340 #ifdef TCP_CSUM_COUNTERS 341 #include <sys/device.h> 342 343 #if defined(INET) 344 extern struct evcnt tcp_hwcsum_ok; 345 extern struct evcnt tcp_hwcsum_bad; 346 extern struct evcnt tcp_hwcsum_data; 347 extern struct evcnt tcp_swcsum; 348 #endif /* defined(INET) */ 349 #if defined(INET6) 350 extern struct evcnt tcp6_hwcsum_ok; 351 extern struct evcnt tcp6_hwcsum_bad; 352 extern struct evcnt tcp6_hwcsum_data; 353 extern struct evcnt tcp6_swcsum; 354 #endif /* defined(INET6) */ 355 356 #define TCP_CSUM_COUNTER_INCR(ev) (ev)->ev_count++ 357 358 #else 359 360 #define TCP_CSUM_COUNTER_INCR(ev) /* nothing */ 361 362 #endif /* TCP_CSUM_COUNTERS */ 363 364 #ifdef TCP_REASS_COUNTERS 365 #include <sys/device.h> 366 367 extern struct evcnt tcp_reass_; 368 extern struct evcnt tcp_reass_empty; 369 extern struct evcnt tcp_reass_iteration[8]; 370 extern struct evcnt tcp_reass_prependfirst; 371 extern struct evcnt tcp_reass_prepend; 372 extern struct evcnt tcp_reass_insert; 373 extern struct evcnt tcp_reass_inserttail; 374 extern struct evcnt tcp_reass_append; 375 extern struct evcnt tcp_reass_appendtail; 376 extern struct evcnt tcp_reass_overlaptail; 377 extern struct evcnt tcp_reass_overlapfront; 378 extern struct evcnt tcp_reass_segdup; 379 extern struct evcnt tcp_reass_fragdup; 380 381 #define TCP_REASS_COUNTER_INCR(ev) (ev)->ev_count++ 382 383 #else 384 385 #define TCP_REASS_COUNTER_INCR(ev) /* nothing */ 386 387 #endif /* TCP_REASS_COUNTERS */ 388 389 static int tcp_reass(struct tcpcb *, const struct tcphdr *, struct mbuf *, 390 int *); 391 static int tcp_dooptions(struct tcpcb *, const u_char *, int, 392 struct tcphdr *, struct mbuf *, int, struct tcp_opt_info *); 393 394 #ifdef INET 395 static void tcp4_log_refused(const struct ip *, const struct tcphdr *); 396 #endif 397 #ifdef INET6 398 static void tcp6_log_refused(const struct ip6_hdr *, const struct tcphdr *); 399 #endif 400 401 #define TRAVERSE(x) while ((x)->m_next) (x) = (x)->m_next 402 403 #if defined(MBUFTRACE) 404 struct mowner tcp_reass_mowner = MOWNER_INIT("tcp", "reass"); 405 #endif /* defined(MBUFTRACE) */ 406 407 static struct pool tcpipqent_pool; 408 409 void 410 tcpipqent_init(void) 411 { 412 413 pool_init(&tcpipqent_pool, sizeof(struct ipqent), 0, 0, 0, "tcpipqepl", 414 NULL, IPL_VM); 415 } 416 417 struct ipqent * 418 tcpipqent_alloc(void) 419 { 420 struct ipqent *ipqe; 421 int s; 422 423 s = splvm(); 424 ipqe = pool_get(&tcpipqent_pool, PR_NOWAIT); 425 splx(s); 426 427 return ipqe; 428 } 429 430 void 431 tcpipqent_free(struct ipqent *ipqe) 432 { 433 int s; 434 435 s = splvm(); 436 pool_put(&tcpipqent_pool, ipqe); 437 splx(s); 438 } 439 440 static int 441 tcp_reass(struct tcpcb *tp, const struct tcphdr *th, struct mbuf *m, int *tlen) 442 { 443 struct ipqent *p, *q, *nq, *tiqe = NULL; 444 struct socket *so = NULL; 445 int pkt_flags; 446 tcp_seq pkt_seq; 447 unsigned pkt_len; 448 u_long rcvpartdupbyte = 0; 449 u_long rcvoobyte; 450 #ifdef TCP_REASS_COUNTERS 451 u_int count = 0; 452 #endif 453 uint64_t *tcps; 454 455 if (tp->t_inpcb) 456 so = tp->t_inpcb->inp_socket; 457 #ifdef INET6 458 else if (tp->t_in6pcb) 459 so = tp->t_in6pcb->in6p_socket; 460 #endif 461 462 TCP_REASS_LOCK_CHECK(tp); 463 464 /* 465 * Call with th==0 after become established to 466 * force pre-ESTABLISHED data up to user socket. 467 */ 468 if (th == 0) 469 goto present; 470 471 m_claimm(m, &tcp_reass_mowner); 472 473 rcvoobyte = *tlen; 474 /* 475 * Copy these to local variables because the tcpiphdr 476 * gets munged while we are collapsing mbufs. 477 */ 478 pkt_seq = th->th_seq; 479 pkt_len = *tlen; 480 pkt_flags = th->th_flags; 481 482 TCP_REASS_COUNTER_INCR(&tcp_reass_); 483 484 if ((p = TAILQ_LAST(&tp->segq, ipqehead)) != NULL) { 485 /* 486 * When we miss a packet, the vast majority of time we get 487 * packets that follow it in order. So optimize for that. 488 */ 489 if (pkt_seq == p->ipqe_seq + p->ipqe_len) { 490 p->ipqe_len += pkt_len; 491 p->ipqe_flags |= pkt_flags; 492 m_cat(p->ipre_mlast, m); 493 TRAVERSE(p->ipre_mlast); 494 m = NULL; 495 tiqe = p; 496 TAILQ_REMOVE(&tp->timeq, p, ipqe_timeq); 497 TCP_REASS_COUNTER_INCR(&tcp_reass_appendtail); 498 goto skip_replacement; 499 } 500 /* 501 * While we're here, if the pkt is completely beyond 502 * anything we have, just insert it at the tail. 503 */ 504 if (SEQ_GT(pkt_seq, p->ipqe_seq + p->ipqe_len)) { 505 TCP_REASS_COUNTER_INCR(&tcp_reass_inserttail); 506 goto insert_it; 507 } 508 } 509 510 q = TAILQ_FIRST(&tp->segq); 511 512 if (q != NULL) { 513 /* 514 * If this segment immediately precedes the first out-of-order 515 * block, simply slap the segment in front of it and (mostly) 516 * skip the complicated logic. 517 */ 518 if (pkt_seq + pkt_len == q->ipqe_seq) { 519 q->ipqe_seq = pkt_seq; 520 q->ipqe_len += pkt_len; 521 q->ipqe_flags |= pkt_flags; 522 m_cat(m, q->ipqe_m); 523 q->ipqe_m = m; 524 q->ipre_mlast = m; /* last mbuf may have changed */ 525 TRAVERSE(q->ipre_mlast); 526 tiqe = q; 527 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 528 TCP_REASS_COUNTER_INCR(&tcp_reass_prependfirst); 529 goto skip_replacement; 530 } 531 } else { 532 TCP_REASS_COUNTER_INCR(&tcp_reass_empty); 533 } 534 535 /* 536 * Find a segment which begins after this one does. 537 */ 538 for (p = NULL; q != NULL; q = nq) { 539 nq = TAILQ_NEXT(q, ipqe_q); 540 #ifdef TCP_REASS_COUNTERS 541 count++; 542 #endif 543 /* 544 * If the received segment is just right after this 545 * fragment, merge the two together and then check 546 * for further overlaps. 547 */ 548 if (q->ipqe_seq + q->ipqe_len == pkt_seq) { 549 #ifdef TCPREASS_DEBUG 550 printf("tcp_reass[%p]: concat %u:%u(%u) to %u:%u(%u)\n", 551 tp, pkt_seq, pkt_seq + pkt_len, pkt_len, 552 q->ipqe_seq, q->ipqe_seq + q->ipqe_len, q->ipqe_len); 553 #endif 554 pkt_len += q->ipqe_len; 555 pkt_flags |= q->ipqe_flags; 556 pkt_seq = q->ipqe_seq; 557 m_cat(q->ipre_mlast, m); 558 TRAVERSE(q->ipre_mlast); 559 m = q->ipqe_m; 560 TCP_REASS_COUNTER_INCR(&tcp_reass_append); 561 goto free_ipqe; 562 } 563 /* 564 * If the received segment is completely past this 565 * fragment, we need to go the next fragment. 566 */ 567 if (SEQ_LT(q->ipqe_seq + q->ipqe_len, pkt_seq)) { 568 p = q; 569 continue; 570 } 571 /* 572 * If the fragment is past the received segment, 573 * it (or any following) can't be concatenated. 574 */ 575 if (SEQ_GT(q->ipqe_seq, pkt_seq + pkt_len)) { 576 TCP_REASS_COUNTER_INCR(&tcp_reass_insert); 577 break; 578 } 579 580 /* 581 * We've received all the data in this segment before. 582 * mark it as a duplicate and return. 583 */ 584 if (SEQ_LEQ(q->ipqe_seq, pkt_seq) && 585 SEQ_GEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) { 586 tcps = TCP_STAT_GETREF(); 587 tcps[TCP_STAT_RCVDUPPACK]++; 588 tcps[TCP_STAT_RCVDUPBYTE] += pkt_len; 589 TCP_STAT_PUTREF(); 590 tcp_new_dsack(tp, pkt_seq, pkt_len); 591 m_freem(m); 592 if (tiqe != NULL) { 593 tcpipqent_free(tiqe); 594 } 595 TCP_REASS_COUNTER_INCR(&tcp_reass_segdup); 596 goto out; 597 } 598 /* 599 * Received segment completely overlaps this fragment 600 * so we drop the fragment (this keeps the temporal 601 * ordering of segments correct). 602 */ 603 if (SEQ_GEQ(q->ipqe_seq, pkt_seq) && 604 SEQ_LEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) { 605 rcvpartdupbyte += q->ipqe_len; 606 m_freem(q->ipqe_m); 607 TCP_REASS_COUNTER_INCR(&tcp_reass_fragdup); 608 goto free_ipqe; 609 } 610 /* 611 * RX'ed segment extends past the end of the 612 * fragment. Drop the overlapping bytes. Then 613 * merge the fragment and segment then treat as 614 * a longer received packet. 615 */ 616 if (SEQ_LT(q->ipqe_seq, pkt_seq) && 617 SEQ_GT(q->ipqe_seq + q->ipqe_len, pkt_seq)) { 618 int overlap = q->ipqe_seq + q->ipqe_len - pkt_seq; 619 #ifdef TCPREASS_DEBUG 620 printf("tcp_reass[%p]: trim starting %d bytes of %u:%u(%u)\n", 621 tp, overlap, 622 pkt_seq, pkt_seq + pkt_len, pkt_len); 623 #endif 624 m_adj(m, overlap); 625 rcvpartdupbyte += overlap; 626 m_cat(q->ipre_mlast, m); 627 TRAVERSE(q->ipre_mlast); 628 m = q->ipqe_m; 629 pkt_seq = q->ipqe_seq; 630 pkt_len += q->ipqe_len - overlap; 631 rcvoobyte -= overlap; 632 TCP_REASS_COUNTER_INCR(&tcp_reass_overlaptail); 633 goto free_ipqe; 634 } 635 /* 636 * RX'ed segment extends past the front of the 637 * fragment. Drop the overlapping bytes on the 638 * received packet. The packet will then be 639 * contatentated with this fragment a bit later. 640 */ 641 if (SEQ_GT(q->ipqe_seq, pkt_seq) && 642 SEQ_LT(q->ipqe_seq, pkt_seq + pkt_len)) { 643 int overlap = pkt_seq + pkt_len - q->ipqe_seq; 644 #ifdef TCPREASS_DEBUG 645 printf("tcp_reass[%p]: trim trailing %d bytes of %u:%u(%u)\n", 646 tp, overlap, 647 pkt_seq, pkt_seq + pkt_len, pkt_len); 648 #endif 649 m_adj(m, -overlap); 650 pkt_len -= overlap; 651 rcvpartdupbyte += overlap; 652 TCP_REASS_COUNTER_INCR(&tcp_reass_overlapfront); 653 rcvoobyte -= overlap; 654 } 655 /* 656 * If the received segment immediates precedes this 657 * fragment then tack the fragment onto this segment 658 * and reinsert the data. 659 */ 660 if (q->ipqe_seq == pkt_seq + pkt_len) { 661 #ifdef TCPREASS_DEBUG 662 printf("tcp_reass[%p]: append %u:%u(%u) to %u:%u(%u)\n", 663 tp, q->ipqe_seq, q->ipqe_seq + q->ipqe_len, q->ipqe_len, 664 pkt_seq, pkt_seq + pkt_len, pkt_len); 665 #endif 666 pkt_len += q->ipqe_len; 667 pkt_flags |= q->ipqe_flags; 668 m_cat(m, q->ipqe_m); 669 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 670 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 671 tp->t_segqlen--; 672 KASSERT(tp->t_segqlen >= 0); 673 KASSERT(tp->t_segqlen != 0 || 674 (TAILQ_EMPTY(&tp->segq) && 675 TAILQ_EMPTY(&tp->timeq))); 676 if (tiqe == NULL) { 677 tiqe = q; 678 } else { 679 tcpipqent_free(q); 680 } 681 TCP_REASS_COUNTER_INCR(&tcp_reass_prepend); 682 break; 683 } 684 /* 685 * If the fragment is before the segment, remember it. 686 * When this loop is terminated, p will contain the 687 * pointer to fragment that is right before the received 688 * segment. 689 */ 690 if (SEQ_LEQ(q->ipqe_seq, pkt_seq)) 691 p = q; 692 693 continue; 694 695 /* 696 * This is a common operation. It also will allow 697 * to save doing a malloc/free in most instances. 698 */ 699 free_ipqe: 700 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 701 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 702 tp->t_segqlen--; 703 KASSERT(tp->t_segqlen >= 0); 704 KASSERT(tp->t_segqlen != 0 || 705 (TAILQ_EMPTY(&tp->segq) && TAILQ_EMPTY(&tp->timeq))); 706 if (tiqe == NULL) { 707 tiqe = q; 708 } else { 709 tcpipqent_free(q); 710 } 711 } 712 713 #ifdef TCP_REASS_COUNTERS 714 if (count > 7) 715 TCP_REASS_COUNTER_INCR(&tcp_reass_iteration[0]); 716 else if (count > 0) 717 TCP_REASS_COUNTER_INCR(&tcp_reass_iteration[count]); 718 #endif 719 720 insert_it: 721 722 /* 723 * Allocate a new queue entry since the received segment did not 724 * collapse onto any other out-of-order block; thus we are allocating 725 * a new block. If it had collapsed, tiqe would not be NULL and 726 * we would be reusing it. 727 * XXX If we can't, just drop the packet. XXX 728 */ 729 if (tiqe == NULL) { 730 tiqe = tcpipqent_alloc(); 731 if (tiqe == NULL) { 732 TCP_STATINC(TCP_STAT_RCVMEMDROP); 733 m_freem(m); 734 goto out; 735 } 736 } 737 738 /* 739 * Update the counters. 740 */ 741 tcps = TCP_STAT_GETREF(); 742 tcps[TCP_STAT_RCVOOPACK]++; 743 tcps[TCP_STAT_RCVOOBYTE] += rcvoobyte; 744 if (rcvpartdupbyte) { 745 tcps[TCP_STAT_RCVPARTDUPPACK]++; 746 tcps[TCP_STAT_RCVPARTDUPBYTE] += rcvpartdupbyte; 747 } 748 TCP_STAT_PUTREF(); 749 750 /* 751 * Insert the new fragment queue entry into both queues. 752 */ 753 tiqe->ipqe_m = m; 754 tiqe->ipre_mlast = m; 755 tiqe->ipqe_seq = pkt_seq; 756 tiqe->ipqe_len = pkt_len; 757 tiqe->ipqe_flags = pkt_flags; 758 if (p == NULL) { 759 TAILQ_INSERT_HEAD(&tp->segq, tiqe, ipqe_q); 760 #ifdef TCPREASS_DEBUG 761 if (tiqe->ipqe_seq != tp->rcv_nxt) 762 printf("tcp_reass[%p]: insert %u:%u(%u) at front\n", 763 tp, pkt_seq, pkt_seq + pkt_len, pkt_len); 764 #endif 765 } else { 766 TAILQ_INSERT_AFTER(&tp->segq, p, tiqe, ipqe_q); 767 #ifdef TCPREASS_DEBUG 768 printf("tcp_reass[%p]: insert %u:%u(%u) after %u:%u(%u)\n", 769 tp, pkt_seq, pkt_seq + pkt_len, pkt_len, 770 p->ipqe_seq, p->ipqe_seq + p->ipqe_len, p->ipqe_len); 771 #endif 772 } 773 tp->t_segqlen++; 774 775 skip_replacement: 776 777 TAILQ_INSERT_HEAD(&tp->timeq, tiqe, ipqe_timeq); 778 779 present: 780 /* 781 * Present data to user, advancing rcv_nxt through 782 * completed sequence space. 783 */ 784 if (TCPS_HAVEESTABLISHED(tp->t_state) == 0) 785 goto out; 786 q = TAILQ_FIRST(&tp->segq); 787 if (q == NULL || q->ipqe_seq != tp->rcv_nxt) 788 goto out; 789 if (tp->t_state == TCPS_SYN_RECEIVED && q->ipqe_len) 790 goto out; 791 792 tp->rcv_nxt += q->ipqe_len; 793 pkt_flags = q->ipqe_flags & TH_FIN; 794 nd6_hint(tp); 795 796 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 797 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 798 tp->t_segqlen--; 799 KASSERT(tp->t_segqlen >= 0); 800 KASSERT(tp->t_segqlen != 0 || 801 (TAILQ_EMPTY(&tp->segq) && TAILQ_EMPTY(&tp->timeq))); 802 if (so->so_state & SS_CANTRCVMORE) 803 m_freem(q->ipqe_m); 804 else 805 sbappendstream(&so->so_rcv, q->ipqe_m); 806 tcpipqent_free(q); 807 TCP_REASS_UNLOCK(tp); 808 sorwakeup(so); 809 return (pkt_flags); 810 out: 811 TCP_REASS_UNLOCK(tp); 812 return (0); 813 } 814 815 #ifdef INET6 816 int 817 tcp6_input(struct mbuf **mp, int *offp, int proto) 818 { 819 struct mbuf *m = *mp; 820 821 /* 822 * draft-itojun-ipv6-tcp-to-anycast 823 * better place to put this in? 824 */ 825 if (m->m_flags & M_ANYCAST6) { 826 struct ip6_hdr *ip6; 827 if (m->m_len < sizeof(struct ip6_hdr)) { 828 if ((m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) { 829 TCP_STATINC(TCP_STAT_RCVSHORT); 830 return IPPROTO_DONE; 831 } 832 } 833 ip6 = mtod(m, struct ip6_hdr *); 834 icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR, 835 (char *)&ip6->ip6_dst - (char *)ip6); 836 return IPPROTO_DONE; 837 } 838 839 tcp_input(m, *offp, proto); 840 return IPPROTO_DONE; 841 } 842 #endif 843 844 #ifdef INET 845 static void 846 tcp4_log_refused(const struct ip *ip, const struct tcphdr *th) 847 { 848 char src[4*sizeof "123"]; 849 char dst[4*sizeof "123"]; 850 851 if (ip) { 852 strlcpy(src, inet_ntoa(ip->ip_src), sizeof(src)); 853 strlcpy(dst, inet_ntoa(ip->ip_dst), sizeof(dst)); 854 } 855 else { 856 strlcpy(src, "(unknown)", sizeof(src)); 857 strlcpy(dst, "(unknown)", sizeof(dst)); 858 } 859 log(LOG_INFO, 860 "Connection attempt to TCP %s:%d from %s:%d\n", 861 dst, ntohs(th->th_dport), 862 src, ntohs(th->th_sport)); 863 } 864 #endif 865 866 #ifdef INET6 867 static void 868 tcp6_log_refused(const struct ip6_hdr *ip6, const struct tcphdr *th) 869 { 870 char src[INET6_ADDRSTRLEN]; 871 char dst[INET6_ADDRSTRLEN]; 872 873 if (ip6) { 874 strlcpy(src, ip6_sprintf(&ip6->ip6_src), sizeof(src)); 875 strlcpy(dst, ip6_sprintf(&ip6->ip6_dst), sizeof(dst)); 876 } 877 else { 878 strlcpy(src, "(unknown v6)", sizeof(src)); 879 strlcpy(dst, "(unknown v6)", sizeof(dst)); 880 } 881 log(LOG_INFO, 882 "Connection attempt to TCP [%s]:%d from [%s]:%d\n", 883 dst, ntohs(th->th_dport), 884 src, ntohs(th->th_sport)); 885 } 886 #endif 887 888 /* 889 * Checksum extended TCP header and data. 890 */ 891 int 892 tcp_input_checksum(int af, struct mbuf *m, const struct tcphdr *th, 893 int toff, int off, int tlen) 894 { 895 896 /* 897 * XXX it's better to record and check if this mbuf is 898 * already checked. 899 */ 900 901 switch (af) { 902 #ifdef INET 903 case AF_INET: 904 switch (m->m_pkthdr.csum_flags & 905 ((m->m_pkthdr.rcvif->if_csum_flags_rx & M_CSUM_TCPv4) | 906 M_CSUM_TCP_UDP_BAD | M_CSUM_DATA)) { 907 case M_CSUM_TCPv4|M_CSUM_TCP_UDP_BAD: 908 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_bad); 909 goto badcsum; 910 911 case M_CSUM_TCPv4|M_CSUM_DATA: { 912 u_int32_t hw_csum = m->m_pkthdr.csum_data; 913 914 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_data); 915 if (m->m_pkthdr.csum_flags & M_CSUM_NO_PSEUDOHDR) { 916 const struct ip *ip = 917 mtod(m, const struct ip *); 918 919 hw_csum = in_cksum_phdr(ip->ip_src.s_addr, 920 ip->ip_dst.s_addr, 921 htons(hw_csum + tlen + off + IPPROTO_TCP)); 922 } 923 if ((hw_csum ^ 0xffff) != 0) 924 goto badcsum; 925 break; 926 } 927 928 case M_CSUM_TCPv4: 929 /* Checksum was okay. */ 930 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_ok); 931 break; 932 933 default: 934 /* 935 * Must compute it ourselves. Maybe skip checksum 936 * on loopback interfaces. 937 */ 938 if (__predict_true(!(m->m_pkthdr.rcvif->if_flags & 939 IFF_LOOPBACK) || 940 tcp_do_loopback_cksum)) { 941 TCP_CSUM_COUNTER_INCR(&tcp_swcsum); 942 if (in4_cksum(m, IPPROTO_TCP, toff, 943 tlen + off) != 0) 944 goto badcsum; 945 } 946 break; 947 } 948 break; 949 #endif /* INET4 */ 950 951 #ifdef INET6 952 case AF_INET6: 953 switch (m->m_pkthdr.csum_flags & 954 ((m->m_pkthdr.rcvif->if_csum_flags_rx & M_CSUM_TCPv6) | 955 M_CSUM_TCP_UDP_BAD | M_CSUM_DATA)) { 956 case M_CSUM_TCPv6|M_CSUM_TCP_UDP_BAD: 957 TCP_CSUM_COUNTER_INCR(&tcp6_hwcsum_bad); 958 goto badcsum; 959 960 #if 0 /* notyet */ 961 case M_CSUM_TCPv6|M_CSUM_DATA: 962 #endif 963 964 case M_CSUM_TCPv6: 965 /* Checksum was okay. */ 966 TCP_CSUM_COUNTER_INCR(&tcp6_hwcsum_ok); 967 break; 968 969 default: 970 /* 971 * Must compute it ourselves. Maybe skip checksum 972 * on loopback interfaces. 973 */ 974 if (__predict_true((m->m_flags & M_LOOP) == 0 || 975 tcp_do_loopback_cksum)) { 976 TCP_CSUM_COUNTER_INCR(&tcp6_swcsum); 977 if (in6_cksum(m, IPPROTO_TCP, toff, 978 tlen + off) != 0) 979 goto badcsum; 980 } 981 } 982 break; 983 #endif /* INET6 */ 984 } 985 986 return 0; 987 988 badcsum: 989 TCP_STATINC(TCP_STAT_RCVBADSUM); 990 return -1; 991 } 992 993 /* When a packet arrives addressed to a vestigial tcpbp, we 994 * nevertheless have to respond to it per the spec. 995 */ 996 static void tcp_vtw_input(struct tcphdr *th, vestigial_inpcb_t *vp, 997 struct mbuf *m, int tlen, int multicast) 998 { 999 int tiflags; 1000 int todrop; 1001 uint32_t t_flags = 0; 1002 uint64_t *tcps; 1003 1004 tiflags = th->th_flags; 1005 todrop = vp->rcv_nxt - th->th_seq; 1006 1007 if (todrop > 0) { 1008 if (tiflags & TH_SYN) { 1009 tiflags &= ~TH_SYN; 1010 ++th->th_seq; 1011 if (th->th_urp > 1) 1012 --th->th_urp; 1013 else { 1014 tiflags &= ~TH_URG; 1015 th->th_urp = 0; 1016 } 1017 --todrop; 1018 } 1019 if (todrop > tlen || 1020 (todrop == tlen && (tiflags & TH_FIN) == 0)) { 1021 /* 1022 * Any valid FIN or RST must be to the left of the 1023 * window. At this point the FIN or RST must be a 1024 * duplicate or out of sequence; drop it. 1025 */ 1026 if (tiflags & TH_RST) 1027 goto drop; 1028 tiflags &= ~(TH_FIN|TH_RST); 1029 /* 1030 * Send an ACK to resynchronize and drop any data. 1031 * But keep on processing for RST or ACK. 1032 */ 1033 t_flags |= TF_ACKNOW; 1034 todrop = tlen; 1035 tcps = TCP_STAT_GETREF(); 1036 tcps[TCP_STAT_RCVDUPPACK] += 1; 1037 tcps[TCP_STAT_RCVDUPBYTE] += todrop; 1038 TCP_STAT_PUTREF(); 1039 } else if ((tiflags & TH_RST) 1040 && th->th_seq != vp->rcv_nxt) { 1041 /* 1042 * Test for reset before adjusting the sequence 1043 * number for overlapping data. 1044 */ 1045 goto dropafterack_ratelim; 1046 } else { 1047 tcps = TCP_STAT_GETREF(); 1048 tcps[TCP_STAT_RCVPARTDUPPACK] += 1; 1049 tcps[TCP_STAT_RCVPARTDUPBYTE] += todrop; 1050 TCP_STAT_PUTREF(); 1051 } 1052 1053 // tcp_new_dsack(tp, th->th_seq, todrop); 1054 // hdroptlen += todrop; /*drop from head afterwards*/ 1055 1056 th->th_seq += todrop; 1057 tlen -= todrop; 1058 1059 if (th->th_urp > todrop) 1060 th->th_urp -= todrop; 1061 else { 1062 tiflags &= ~TH_URG; 1063 th->th_urp = 0; 1064 } 1065 } 1066 1067 /* 1068 * If new data are received on a connection after the 1069 * user processes are gone, then RST the other end. 1070 */ 1071 if (tlen) { 1072 TCP_STATINC(TCP_STAT_RCVAFTERCLOSE); 1073 goto dropwithreset; 1074 } 1075 1076 /* 1077 * If segment ends after window, drop trailing data 1078 * (and PUSH and FIN); if nothing left, just ACK. 1079 */ 1080 todrop = (th->th_seq + tlen) - (vp->rcv_nxt+vp->rcv_wnd); 1081 1082 if (todrop > 0) { 1083 TCP_STATINC(TCP_STAT_RCVPACKAFTERWIN); 1084 if (todrop >= tlen) { 1085 /* 1086 * The segment actually starts after the window. 1087 * th->th_seq + tlen - vp->rcv_nxt - vp->rcv_wnd >= tlen 1088 * th->th_seq - vp->rcv_nxt - vp->rcv_wnd >= 0 1089 * th->th_seq >= vp->rcv_nxt + vp->rcv_wnd 1090 */ 1091 TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, tlen); 1092 /* 1093 * If a new connection request is received 1094 * while in TIME_WAIT, drop the old connection 1095 * and start over if the sequence numbers 1096 * are above the previous ones. 1097 */ 1098 if ((tiflags & TH_SYN) 1099 && SEQ_GT(th->th_seq, vp->rcv_nxt)) { 1100 /* We only support this in the !NOFDREF case, which 1101 * is to say: not here. 1102 */ 1103 goto dropwithreset; 1104 } 1105 /* 1106 * If window is closed can only take segments at 1107 * window edge, and have to drop data and PUSH from 1108 * incoming segments. Continue processing, but 1109 * remember to ack. Otherwise, drop segment 1110 * and (if not RST) ack. 1111 */ 1112 if (vp->rcv_wnd == 0 && th->th_seq == vp->rcv_nxt) { 1113 t_flags |= TF_ACKNOW; 1114 TCP_STATINC(TCP_STAT_RCVWINPROBE); 1115 } else 1116 goto dropafterack; 1117 } else 1118 TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, todrop); 1119 m_adj(m, -todrop); 1120 tlen -= todrop; 1121 tiflags &= ~(TH_PUSH|TH_FIN); 1122 } 1123 1124 if (tiflags & TH_RST) { 1125 if (th->th_seq != vp->rcv_nxt) 1126 goto dropafterack_ratelim; 1127 1128 vtw_del(vp->ctl, vp->vtw); 1129 goto drop; 1130 } 1131 1132 /* 1133 * If the ACK bit is off we drop the segment and return. 1134 */ 1135 if ((tiflags & TH_ACK) == 0) { 1136 if (t_flags & TF_ACKNOW) 1137 goto dropafterack; 1138 else 1139 goto drop; 1140 } 1141 1142 /* 1143 * In TIME_WAIT state the only thing that should arrive 1144 * is a retransmission of the remote FIN. Acknowledge 1145 * it and restart the finack timer. 1146 */ 1147 vtw_restart(vp); 1148 goto dropafterack; 1149 1150 dropafterack: 1151 /* 1152 * Generate an ACK dropping incoming segment if it occupies 1153 * sequence space, where the ACK reflects our state. 1154 */ 1155 if (tiflags & TH_RST) 1156 goto drop; 1157 goto dropafterack2; 1158 1159 dropafterack_ratelim: 1160 /* 1161 * We may want to rate-limit ACKs against SYN/RST attack. 1162 */ 1163 if (ppsratecheck(&tcp_ackdrop_ppslim_last, &tcp_ackdrop_ppslim_count, 1164 tcp_ackdrop_ppslim) == 0) { 1165 /* XXX stat */ 1166 goto drop; 1167 } 1168 /* ...fall into dropafterack2... */ 1169 1170 dropafterack2: 1171 (void)tcp_respond(0, m, m, th, th->th_seq + tlen, th->th_ack, 1172 TH_ACK); 1173 return; 1174 1175 dropwithreset: 1176 /* 1177 * Generate a RST, dropping incoming segment. 1178 * Make ACK acceptable to originator of segment. 1179 */ 1180 if (tiflags & TH_RST) 1181 goto drop; 1182 1183 if (tiflags & TH_ACK) 1184 tcp_respond(0, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 1185 else { 1186 if (tiflags & TH_SYN) 1187 ++tlen; 1188 (void)tcp_respond(0, m, m, th, th->th_seq + tlen, (tcp_seq)0, 1189 TH_RST|TH_ACK); 1190 } 1191 return; 1192 drop: 1193 m_freem(m); 1194 } 1195 1196 /* 1197 * TCP input routine, follows pages 65-76 of RFC 793 very closely. 1198 */ 1199 void 1200 tcp_input(struct mbuf *m, ...) 1201 { 1202 struct tcphdr *th; 1203 struct ip *ip; 1204 struct inpcb *inp; 1205 #ifdef INET6 1206 struct ip6_hdr *ip6; 1207 struct in6pcb *in6p; 1208 #endif 1209 u_int8_t *optp = NULL; 1210 int optlen = 0; 1211 int len, tlen, toff, hdroptlen = 0; 1212 struct tcpcb *tp = 0; 1213 int tiflags; 1214 struct socket *so = NULL; 1215 int todrop, acked, ourfinisacked, needoutput = 0; 1216 bool dupseg; 1217 #ifdef TCP_DEBUG 1218 short ostate = 0; 1219 #endif 1220 u_long tiwin; 1221 struct tcp_opt_info opti; 1222 int off, iphlen; 1223 va_list ap; 1224 int af; /* af on the wire */ 1225 struct mbuf *tcp_saveti = NULL; 1226 uint32_t ts_rtt; 1227 uint8_t iptos; 1228 uint64_t *tcps; 1229 vestigial_inpcb_t vestige; 1230 1231 vestige.valid = 0; 1232 1233 MCLAIM(m, &tcp_rx_mowner); 1234 va_start(ap, m); 1235 toff = va_arg(ap, int); 1236 (void)va_arg(ap, int); /* ignore value, advance ap */ 1237 va_end(ap); 1238 1239 TCP_STATINC(TCP_STAT_RCVTOTAL); 1240 1241 memset(&opti, 0, sizeof(opti)); 1242 opti.ts_present = 0; 1243 opti.maxseg = 0; 1244 1245 /* 1246 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN. 1247 * 1248 * TCP is, by definition, unicast, so we reject all 1249 * multicast outright. 1250 * 1251 * Note, there are additional src/dst address checks in 1252 * the AF-specific code below. 1253 */ 1254 if (m->m_flags & (M_BCAST|M_MCAST)) { 1255 /* XXX stat */ 1256 goto drop; 1257 } 1258 #ifdef INET6 1259 if (m->m_flags & M_ANYCAST6) { 1260 /* XXX stat */ 1261 goto drop; 1262 } 1263 #endif 1264 1265 /* 1266 * Get IP and TCP header. 1267 * Note: IP leaves IP header in first mbuf. 1268 */ 1269 ip = mtod(m, struct ip *); 1270 switch (ip->ip_v) { 1271 #ifdef INET 1272 case 4: 1273 #ifdef INET6 1274 ip6 = NULL; 1275 #endif 1276 af = AF_INET; 1277 iphlen = sizeof(struct ip); 1278 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, 1279 sizeof(struct tcphdr)); 1280 if (th == NULL) { 1281 TCP_STATINC(TCP_STAT_RCVSHORT); 1282 return; 1283 } 1284 /* We do the checksum after PCB lookup... */ 1285 len = ntohs(ip->ip_len); 1286 tlen = len - toff; 1287 iptos = ip->ip_tos; 1288 break; 1289 #endif 1290 #ifdef INET6 1291 case 6: 1292 ip = NULL; 1293 iphlen = sizeof(struct ip6_hdr); 1294 af = AF_INET6; 1295 ip6 = mtod(m, struct ip6_hdr *); 1296 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, 1297 sizeof(struct tcphdr)); 1298 if (th == NULL) { 1299 TCP_STATINC(TCP_STAT_RCVSHORT); 1300 return; 1301 } 1302 1303 /* Be proactive about malicious use of IPv4 mapped address */ 1304 if (IN6_IS_ADDR_V4MAPPED(&ip6->ip6_src) || 1305 IN6_IS_ADDR_V4MAPPED(&ip6->ip6_dst)) { 1306 /* XXX stat */ 1307 goto drop; 1308 } 1309 1310 /* 1311 * Be proactive about unspecified IPv6 address in source. 1312 * As we use all-zero to indicate unbounded/unconnected pcb, 1313 * unspecified IPv6 address can be used to confuse us. 1314 * 1315 * Note that packets with unspecified IPv6 destination is 1316 * already dropped in ip6_input. 1317 */ 1318 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 1319 /* XXX stat */ 1320 goto drop; 1321 } 1322 1323 /* 1324 * Make sure destination address is not multicast. 1325 * Source address checked in ip6_input(). 1326 */ 1327 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) { 1328 /* XXX stat */ 1329 goto drop; 1330 } 1331 1332 /* We do the checksum after PCB lookup... */ 1333 len = m->m_pkthdr.len; 1334 tlen = len - toff; 1335 iptos = (ntohl(ip6->ip6_flow) >> 20) & 0xff; 1336 break; 1337 #endif 1338 default: 1339 m_freem(m); 1340 return; 1341 } 1342 1343 KASSERT(TCP_HDR_ALIGNED_P(th)); 1344 1345 /* 1346 * Check that TCP offset makes sense, 1347 * pull out TCP options and adjust length. XXX 1348 */ 1349 off = th->th_off << 2; 1350 if (off < sizeof (struct tcphdr) || off > tlen) { 1351 TCP_STATINC(TCP_STAT_RCVBADOFF); 1352 goto drop; 1353 } 1354 tlen -= off; 1355 1356 /* 1357 * tcp_input() has been modified to use tlen to mean the TCP data 1358 * length throughout the function. Other functions can use 1359 * m->m_pkthdr.len as the basis for calculating the TCP data length. 1360 * rja 1361 */ 1362 1363 if (off > sizeof (struct tcphdr)) { 1364 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, off); 1365 if (th == NULL) { 1366 TCP_STATINC(TCP_STAT_RCVSHORT); 1367 return; 1368 } 1369 /* 1370 * NOTE: ip/ip6 will not be affected by m_pulldown() 1371 * (as they're before toff) and we don't need to update those. 1372 */ 1373 KASSERT(TCP_HDR_ALIGNED_P(th)); 1374 optlen = off - sizeof (struct tcphdr); 1375 optp = ((u_int8_t *)th) + sizeof(struct tcphdr); 1376 /* 1377 * Do quick retrieval of timestamp options ("options 1378 * prediction?"). If timestamp is the only option and it's 1379 * formatted as recommended in RFC 1323 appendix A, we 1380 * quickly get the values now and not bother calling 1381 * tcp_dooptions(), etc. 1382 */ 1383 if ((optlen == TCPOLEN_TSTAMP_APPA || 1384 (optlen > TCPOLEN_TSTAMP_APPA && 1385 optp[TCPOLEN_TSTAMP_APPA] == TCPOPT_EOL)) && 1386 *(u_int32_t *)optp == htonl(TCPOPT_TSTAMP_HDR) && 1387 (th->th_flags & TH_SYN) == 0) { 1388 opti.ts_present = 1; 1389 opti.ts_val = ntohl(*(u_int32_t *)(optp + 4)); 1390 opti.ts_ecr = ntohl(*(u_int32_t *)(optp + 8)); 1391 optp = NULL; /* we've parsed the options */ 1392 } 1393 } 1394 tiflags = th->th_flags; 1395 1396 /* 1397 * Locate pcb for segment. 1398 */ 1399 findpcb: 1400 inp = NULL; 1401 #ifdef INET6 1402 in6p = NULL; 1403 #endif 1404 switch (af) { 1405 #ifdef INET 1406 case AF_INET: 1407 inp = in_pcblookup_connect(&tcbtable, ip->ip_src, th->th_sport, 1408 ip->ip_dst, th->th_dport, 1409 &vestige); 1410 if (inp == 0 && !vestige.valid) { 1411 TCP_STATINC(TCP_STAT_PCBHASHMISS); 1412 inp = in_pcblookup_bind(&tcbtable, ip->ip_dst, th->th_dport); 1413 } 1414 #ifdef INET6 1415 if (inp == 0 && !vestige.valid) { 1416 struct in6_addr s, d; 1417 1418 /* mapped addr case */ 1419 memset(&s, 0, sizeof(s)); 1420 s.s6_addr16[5] = htons(0xffff); 1421 bcopy(&ip->ip_src, &s.s6_addr32[3], sizeof(ip->ip_src)); 1422 memset(&d, 0, sizeof(d)); 1423 d.s6_addr16[5] = htons(0xffff); 1424 bcopy(&ip->ip_dst, &d.s6_addr32[3], sizeof(ip->ip_dst)); 1425 in6p = in6_pcblookup_connect(&tcbtable, &s, 1426 th->th_sport, &d, th->th_dport, 1427 0, &vestige); 1428 if (in6p == 0 && !vestige.valid) { 1429 TCP_STATINC(TCP_STAT_PCBHASHMISS); 1430 in6p = in6_pcblookup_bind(&tcbtable, &d, 1431 th->th_dport, 0); 1432 } 1433 } 1434 #endif 1435 #ifndef INET6 1436 if (inp == 0 && !vestige.valid) 1437 #else 1438 if (inp == 0 && in6p == 0 && !vestige.valid) 1439 #endif 1440 { 1441 TCP_STATINC(TCP_STAT_NOPORT); 1442 if (tcp_log_refused && 1443 (tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) { 1444 tcp4_log_refused(ip, th); 1445 } 1446 tcp_fields_to_host(th); 1447 goto dropwithreset_ratelim; 1448 } 1449 #if defined(IPSEC) 1450 if (ipsec_used) { 1451 if (inp && 1452 (inp->inp_socket->so_options & SO_ACCEPTCONN) == 0 1453 && ipsec4_in_reject(m, inp)) { 1454 IPSEC_STATINC(IPSEC_STAT_IN_POLVIO); 1455 goto drop; 1456 } 1457 #ifdef INET6 1458 else if (in6p && 1459 (in6p->in6p_socket->so_options & SO_ACCEPTCONN) == 0 1460 && ipsec6_in_reject_so(m, in6p->in6p_socket)) { 1461 IPSEC_STATINC(IPSEC_STAT_IN_POLVIO); 1462 goto drop; 1463 } 1464 #endif 1465 } 1466 #endif /*IPSEC*/ 1467 break; 1468 #endif /*INET*/ 1469 #ifdef INET6 1470 case AF_INET6: 1471 { 1472 int faith; 1473 1474 #if defined(NFAITH) && NFAITH > 0 1475 faith = faithprefix(&ip6->ip6_dst); 1476 #else 1477 faith = 0; 1478 #endif 1479 in6p = in6_pcblookup_connect(&tcbtable, &ip6->ip6_src, 1480 th->th_sport, &ip6->ip6_dst, th->th_dport, faith, &vestige); 1481 if (!in6p && !vestige.valid) { 1482 TCP_STATINC(TCP_STAT_PCBHASHMISS); 1483 in6p = in6_pcblookup_bind(&tcbtable, &ip6->ip6_dst, 1484 th->th_dport, faith); 1485 } 1486 if (!in6p && !vestige.valid) { 1487 TCP_STATINC(TCP_STAT_NOPORT); 1488 if (tcp_log_refused && 1489 (tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) { 1490 tcp6_log_refused(ip6, th); 1491 } 1492 tcp_fields_to_host(th); 1493 goto dropwithreset_ratelim; 1494 } 1495 #if defined(IPSEC) 1496 if (ipsec_used && in6p 1497 && (in6p->in6p_socket->so_options & SO_ACCEPTCONN) == 0 1498 && ipsec6_in_reject(m, in6p)) { 1499 IPSEC6_STATINC(IPSEC_STAT_IN_POLVIO); 1500 goto drop; 1501 } 1502 #endif /*IPSEC*/ 1503 break; 1504 } 1505 #endif 1506 } 1507 1508 /* 1509 * If the state is CLOSED (i.e., TCB does not exist) then 1510 * all data in the incoming segment is discarded. 1511 * If the TCB exists but is in CLOSED state, it is embryonic, 1512 * but should either do a listen or a connect soon. 1513 */ 1514 tp = NULL; 1515 so = NULL; 1516 if (inp) { 1517 /* Check the minimum TTL for socket. */ 1518 if (ip->ip_ttl < inp->inp_ip_minttl) 1519 goto drop; 1520 1521 tp = intotcpcb(inp); 1522 so = inp->inp_socket; 1523 } 1524 #ifdef INET6 1525 else if (in6p) { 1526 tp = in6totcpcb(in6p); 1527 so = in6p->in6p_socket; 1528 } 1529 #endif 1530 else if (vestige.valid) { 1531 int mc = 0; 1532 1533 /* We do not support the resurrection of vtw tcpcps. 1534 */ 1535 if (tcp_input_checksum(af, m, th, toff, off, tlen)) 1536 goto badcsum; 1537 1538 switch (af) { 1539 #ifdef INET6 1540 case AF_INET6: 1541 mc = IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst); 1542 break; 1543 #endif 1544 1545 case AF_INET: 1546 mc = (IN_MULTICAST(ip->ip_dst.s_addr) 1547 || in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)); 1548 break; 1549 } 1550 1551 tcp_fields_to_host(th); 1552 tcp_vtw_input(th, &vestige, m, tlen, mc); 1553 m = 0; 1554 goto drop; 1555 } 1556 1557 if (tp == 0) { 1558 tcp_fields_to_host(th); 1559 goto dropwithreset_ratelim; 1560 } 1561 if (tp->t_state == TCPS_CLOSED) 1562 goto drop; 1563 1564 KASSERT(so->so_lock == softnet_lock); 1565 KASSERT(solocked(so)); 1566 1567 /* 1568 * Checksum extended TCP header and data. 1569 */ 1570 if (tcp_input_checksum(af, m, th, toff, off, tlen)) 1571 goto badcsum; 1572 1573 tcp_fields_to_host(th); 1574 1575 /* Unscale the window into a 32-bit value. */ 1576 if ((tiflags & TH_SYN) == 0) 1577 tiwin = th->th_win << tp->snd_scale; 1578 else 1579 tiwin = th->th_win; 1580 1581 #ifdef INET6 1582 /* save packet options if user wanted */ 1583 if (in6p && (in6p->in6p_flags & IN6P_CONTROLOPTS)) { 1584 if (in6p->in6p_options) { 1585 m_freem(in6p->in6p_options); 1586 in6p->in6p_options = 0; 1587 } 1588 KASSERT(ip6 != NULL); 1589 ip6_savecontrol(in6p, &in6p->in6p_options, ip6, m); 1590 } 1591 #endif 1592 1593 if (so->so_options & (SO_DEBUG|SO_ACCEPTCONN)) { 1594 union syn_cache_sa src; 1595 union syn_cache_sa dst; 1596 1597 memset(&src, 0, sizeof(src)); 1598 memset(&dst, 0, sizeof(dst)); 1599 switch (af) { 1600 #ifdef INET 1601 case AF_INET: 1602 src.sin.sin_len = sizeof(struct sockaddr_in); 1603 src.sin.sin_family = AF_INET; 1604 src.sin.sin_addr = ip->ip_src; 1605 src.sin.sin_port = th->th_sport; 1606 1607 dst.sin.sin_len = sizeof(struct sockaddr_in); 1608 dst.sin.sin_family = AF_INET; 1609 dst.sin.sin_addr = ip->ip_dst; 1610 dst.sin.sin_port = th->th_dport; 1611 break; 1612 #endif 1613 #ifdef INET6 1614 case AF_INET6: 1615 src.sin6.sin6_len = sizeof(struct sockaddr_in6); 1616 src.sin6.sin6_family = AF_INET6; 1617 src.sin6.sin6_addr = ip6->ip6_src; 1618 src.sin6.sin6_port = th->th_sport; 1619 1620 dst.sin6.sin6_len = sizeof(struct sockaddr_in6); 1621 dst.sin6.sin6_family = AF_INET6; 1622 dst.sin6.sin6_addr = ip6->ip6_dst; 1623 dst.sin6.sin6_port = th->th_dport; 1624 break; 1625 #endif /* INET6 */ 1626 default: 1627 goto badsyn; /*sanity*/ 1628 } 1629 1630 if (so->so_options & SO_DEBUG) { 1631 #ifdef TCP_DEBUG 1632 ostate = tp->t_state; 1633 #endif 1634 1635 tcp_saveti = NULL; 1636 if (iphlen + sizeof(struct tcphdr) > MHLEN) 1637 goto nosave; 1638 1639 if (m->m_len > iphlen && (m->m_flags & M_EXT) == 0) { 1640 tcp_saveti = m_copym(m, 0, iphlen, M_DONTWAIT); 1641 if (!tcp_saveti) 1642 goto nosave; 1643 } else { 1644 MGETHDR(tcp_saveti, M_DONTWAIT, MT_HEADER); 1645 if (!tcp_saveti) 1646 goto nosave; 1647 MCLAIM(m, &tcp_mowner); 1648 tcp_saveti->m_len = iphlen; 1649 m_copydata(m, 0, iphlen, 1650 mtod(tcp_saveti, void *)); 1651 } 1652 1653 if (M_TRAILINGSPACE(tcp_saveti) < sizeof(struct tcphdr)) { 1654 m_freem(tcp_saveti); 1655 tcp_saveti = NULL; 1656 } else { 1657 tcp_saveti->m_len += sizeof(struct tcphdr); 1658 memcpy(mtod(tcp_saveti, char *) + iphlen, th, 1659 sizeof(struct tcphdr)); 1660 } 1661 nosave:; 1662 } 1663 if (so->so_options & SO_ACCEPTCONN) { 1664 if ((tiflags & (TH_RST|TH_ACK|TH_SYN)) != TH_SYN) { 1665 if (tiflags & TH_RST) { 1666 syn_cache_reset(&src.sa, &dst.sa, th); 1667 } else if ((tiflags & (TH_ACK|TH_SYN)) == 1668 (TH_ACK|TH_SYN)) { 1669 /* 1670 * Received a SYN,ACK. This should 1671 * never happen while we are in 1672 * LISTEN. Send an RST. 1673 */ 1674 goto badsyn; 1675 } else if (tiflags & TH_ACK) { 1676 so = syn_cache_get(&src.sa, &dst.sa, 1677 th, toff, tlen, so, m); 1678 if (so == NULL) { 1679 /* 1680 * We don't have a SYN for 1681 * this ACK; send an RST. 1682 */ 1683 goto badsyn; 1684 } else if (so == 1685 (struct socket *)(-1)) { 1686 /* 1687 * We were unable to create 1688 * the connection. If the 1689 * 3-way handshake was 1690 * completed, and RST has 1691 * been sent to the peer. 1692 * Since the mbuf might be 1693 * in use for the reply, 1694 * do not free it. 1695 */ 1696 m = NULL; 1697 } else { 1698 /* 1699 * We have created a 1700 * full-blown connection. 1701 */ 1702 tp = NULL; 1703 inp = NULL; 1704 #ifdef INET6 1705 in6p = NULL; 1706 #endif 1707 switch (so->so_proto->pr_domain->dom_family) { 1708 #ifdef INET 1709 case AF_INET: 1710 inp = sotoinpcb(so); 1711 tp = intotcpcb(inp); 1712 break; 1713 #endif 1714 #ifdef INET6 1715 case AF_INET6: 1716 in6p = sotoin6pcb(so); 1717 tp = in6totcpcb(in6p); 1718 break; 1719 #endif 1720 } 1721 if (tp == NULL) 1722 goto badsyn; /*XXX*/ 1723 tiwin <<= tp->snd_scale; 1724 goto after_listen; 1725 } 1726 } else { 1727 /* 1728 * None of RST, SYN or ACK was set. 1729 * This is an invalid packet for a 1730 * TCB in LISTEN state. Send a RST. 1731 */ 1732 goto badsyn; 1733 } 1734 } else { 1735 /* 1736 * Received a SYN. 1737 * 1738 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN 1739 */ 1740 if (m->m_flags & (M_BCAST|M_MCAST)) 1741 goto drop; 1742 1743 switch (af) { 1744 #ifdef INET6 1745 case AF_INET6: 1746 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) 1747 goto drop; 1748 break; 1749 #endif /* INET6 */ 1750 case AF_INET: 1751 if (IN_MULTICAST(ip->ip_dst.s_addr) || 1752 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 1753 goto drop; 1754 break; 1755 } 1756 1757 #ifdef INET6 1758 /* 1759 * If deprecated address is forbidden, we do 1760 * not accept SYN to deprecated interface 1761 * address to prevent any new inbound 1762 * connection from getting established. 1763 * When we do not accept SYN, we send a TCP 1764 * RST, with deprecated source address (instead 1765 * of dropping it). We compromise it as it is 1766 * much better for peer to send a RST, and 1767 * RST will be the final packet for the 1768 * exchange. 1769 * 1770 * If we do not forbid deprecated addresses, we 1771 * accept the SYN packet. RFC2462 does not 1772 * suggest dropping SYN in this case. 1773 * If we decipher RFC2462 5.5.4, it says like 1774 * this: 1775 * 1. use of deprecated addr with existing 1776 * communication is okay - "SHOULD continue 1777 * to be used" 1778 * 2. use of it with new communication: 1779 * (2a) "SHOULD NOT be used if alternate 1780 * address with sufficient scope is 1781 * available" 1782 * (2b) nothing mentioned otherwise. 1783 * Here we fall into (2b) case as we have no 1784 * choice in our source address selection - we 1785 * must obey the peer. 1786 * 1787 * The wording in RFC2462 is confusing, and 1788 * there are multiple description text for 1789 * deprecated address handling - worse, they 1790 * are not exactly the same. I believe 5.5.4 1791 * is the best one, so we follow 5.5.4. 1792 */ 1793 if (af == AF_INET6 && !ip6_use_deprecated) { 1794 struct in6_ifaddr *ia6; 1795 if ((ia6 = in6ifa_ifpwithaddr(m->m_pkthdr.rcvif, 1796 &ip6->ip6_dst)) && 1797 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) { 1798 tp = NULL; 1799 goto dropwithreset; 1800 } 1801 } 1802 #endif 1803 1804 #if defined(IPSEC) 1805 if (ipsec_used) { 1806 switch (af) { 1807 #ifdef INET 1808 case AF_INET: 1809 if (!ipsec4_in_reject_so(m, so)) 1810 break; 1811 IPSEC_STATINC( 1812 IPSEC_STAT_IN_POLVIO); 1813 tp = NULL; 1814 goto dropwithreset; 1815 #endif 1816 #ifdef INET6 1817 case AF_INET6: 1818 if (!ipsec6_in_reject_so(m, so)) 1819 break; 1820 IPSEC6_STATINC( 1821 IPSEC_STAT_IN_POLVIO); 1822 tp = NULL; 1823 goto dropwithreset; 1824 #endif /*INET6*/ 1825 } 1826 } 1827 #endif /*IPSEC*/ 1828 1829 /* 1830 * LISTEN socket received a SYN 1831 * from itself? This can't possibly 1832 * be valid; drop the packet. 1833 */ 1834 if (th->th_sport == th->th_dport) { 1835 int i; 1836 1837 switch (af) { 1838 #ifdef INET 1839 case AF_INET: 1840 i = in_hosteq(ip->ip_src, ip->ip_dst); 1841 break; 1842 #endif 1843 #ifdef INET6 1844 case AF_INET6: 1845 i = IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &ip6->ip6_dst); 1846 break; 1847 #endif 1848 default: 1849 i = 1; 1850 } 1851 if (i) { 1852 TCP_STATINC(TCP_STAT_BADSYN); 1853 goto drop; 1854 } 1855 } 1856 1857 /* 1858 * SYN looks ok; create compressed TCP 1859 * state for it. 1860 */ 1861 if (so->so_qlen <= so->so_qlimit && 1862 syn_cache_add(&src.sa, &dst.sa, th, tlen, 1863 so, m, optp, optlen, &opti)) 1864 m = NULL; 1865 } 1866 goto drop; 1867 } 1868 } 1869 1870 after_listen: 1871 #ifdef DIAGNOSTIC 1872 /* 1873 * Should not happen now that all embryonic connections 1874 * are handled with compressed state. 1875 */ 1876 if (tp->t_state == TCPS_LISTEN) 1877 panic("tcp_input: TCPS_LISTEN"); 1878 #endif 1879 1880 /* 1881 * Segment received on connection. 1882 * Reset idle time and keep-alive timer. 1883 */ 1884 tp->t_rcvtime = tcp_now; 1885 if (TCPS_HAVEESTABLISHED(tp->t_state)) 1886 TCP_TIMER_ARM(tp, TCPT_KEEP, tp->t_keepidle); 1887 1888 /* 1889 * Process options. 1890 */ 1891 #ifdef TCP_SIGNATURE 1892 if (optp || (tp->t_flags & TF_SIGNATURE)) 1893 #else 1894 if (optp) 1895 #endif 1896 if (tcp_dooptions(tp, optp, optlen, th, m, toff, &opti) < 0) 1897 goto drop; 1898 1899 if (TCP_SACK_ENABLED(tp)) { 1900 tcp_del_sackholes(tp, th); 1901 } 1902 1903 if (TCP_ECN_ALLOWED(tp)) { 1904 if (tiflags & TH_CWR) { 1905 tp->t_flags &= ~TF_ECN_SND_ECE; 1906 } 1907 switch (iptos & IPTOS_ECN_MASK) { 1908 case IPTOS_ECN_CE: 1909 tp->t_flags |= TF_ECN_SND_ECE; 1910 TCP_STATINC(TCP_STAT_ECN_CE); 1911 break; 1912 case IPTOS_ECN_ECT0: 1913 TCP_STATINC(TCP_STAT_ECN_ECT); 1914 break; 1915 case IPTOS_ECN_ECT1: 1916 /* XXX: ignore for now -- rpaulo */ 1917 break; 1918 } 1919 /* 1920 * Congestion experienced. 1921 * Ignore if we are already trying to recover. 1922 */ 1923 if ((tiflags & TH_ECE) && SEQ_GEQ(tp->snd_una, tp->snd_recover)) 1924 tp->t_congctl->cong_exp(tp); 1925 } 1926 1927 if (opti.ts_present && opti.ts_ecr) { 1928 /* 1929 * Calculate the RTT from the returned time stamp and the 1930 * connection's time base. If the time stamp is later than 1931 * the current time, or is extremely old, fall back to non-1323 1932 * RTT calculation. Since ts_rtt is unsigned, we can test both 1933 * at the same time. 1934 * 1935 * Note that ts_rtt is in units of slow ticks (500 1936 * ms). Since most earthbound RTTs are < 500 ms, 1937 * observed values will have large quantization noise. 1938 * Our smoothed RTT is then the fraction of observed 1939 * samples that are 1 tick instead of 0 (times 500 1940 * ms). 1941 * 1942 * ts_rtt is increased by 1 to denote a valid sample, 1943 * with 0 indicating an invalid measurement. This 1944 * extra 1 must be removed when ts_rtt is used, or 1945 * else an an erroneous extra 500 ms will result. 1946 */ 1947 ts_rtt = TCP_TIMESTAMP(tp) - opti.ts_ecr + 1; 1948 if (ts_rtt > TCP_PAWS_IDLE) 1949 ts_rtt = 0; 1950 } else { 1951 ts_rtt = 0; 1952 } 1953 1954 /* 1955 * Header prediction: check for the two common cases 1956 * of a uni-directional data xfer. If the packet has 1957 * no control flags, is in-sequence, the window didn't 1958 * change and we're not retransmitting, it's a 1959 * candidate. If the length is zero and the ack moved 1960 * forward, we're the sender side of the xfer. Just 1961 * free the data acked & wake any higher level process 1962 * that was blocked waiting for space. If the length 1963 * is non-zero and the ack didn't move, we're the 1964 * receiver side. If we're getting packets in-order 1965 * (the reassembly queue is empty), add the data to 1966 * the socket buffer and note that we need a delayed ack. 1967 */ 1968 if (tp->t_state == TCPS_ESTABLISHED && 1969 (tiflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ECE|TH_CWR|TH_ACK)) 1970 == TH_ACK && 1971 (!opti.ts_present || TSTMP_GEQ(opti.ts_val, tp->ts_recent)) && 1972 th->th_seq == tp->rcv_nxt && 1973 tiwin && tiwin == tp->snd_wnd && 1974 tp->snd_nxt == tp->snd_max) { 1975 1976 /* 1977 * If last ACK falls within this segment's sequence numbers, 1978 * record the timestamp. 1979 * NOTE that the test is modified according to the latest 1980 * proposal of the tcplw (at) cray.com list (Braden 1993/04/26). 1981 * 1982 * note that we already know 1983 * TSTMP_GEQ(opti.ts_val, tp->ts_recent) 1984 */ 1985 if (opti.ts_present && 1986 SEQ_LEQ(th->th_seq, tp->last_ack_sent)) { 1987 tp->ts_recent_age = tcp_now; 1988 tp->ts_recent = opti.ts_val; 1989 } 1990 1991 if (tlen == 0) { 1992 /* Ack prediction. */ 1993 if (SEQ_GT(th->th_ack, tp->snd_una) && 1994 SEQ_LEQ(th->th_ack, tp->snd_max) && 1995 tp->snd_cwnd >= tp->snd_wnd && 1996 tp->t_partialacks < 0) { 1997 /* 1998 * this is a pure ack for outstanding data. 1999 */ 2000 if (ts_rtt) 2001 tcp_xmit_timer(tp, ts_rtt - 1); 2002 else if (tp->t_rtttime && 2003 SEQ_GT(th->th_ack, tp->t_rtseq)) 2004 tcp_xmit_timer(tp, 2005 tcp_now - tp->t_rtttime); 2006 acked = th->th_ack - tp->snd_una; 2007 tcps = TCP_STAT_GETREF(); 2008 tcps[TCP_STAT_PREDACK]++; 2009 tcps[TCP_STAT_RCVACKPACK]++; 2010 tcps[TCP_STAT_RCVACKBYTE] += acked; 2011 TCP_STAT_PUTREF(); 2012 nd6_hint(tp); 2013 2014 if (acked > (tp->t_lastoff - tp->t_inoff)) 2015 tp->t_lastm = NULL; 2016 sbdrop(&so->so_snd, acked); 2017 tp->t_lastoff -= acked; 2018 2019 icmp_check(tp, th, acked); 2020 2021 tp->snd_una = th->th_ack; 2022 tp->snd_fack = tp->snd_una; 2023 if (SEQ_LT(tp->snd_high, tp->snd_una)) 2024 tp->snd_high = tp->snd_una; 2025 m_freem(m); 2026 2027 /* 2028 * If all outstanding data are acked, stop 2029 * retransmit timer, otherwise restart timer 2030 * using current (possibly backed-off) value. 2031 * If process is waiting for space, 2032 * wakeup/selnotify/signal. If data 2033 * are ready to send, let tcp_output 2034 * decide between more output or persist. 2035 */ 2036 if (tp->snd_una == tp->snd_max) 2037 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2038 else if (TCP_TIMER_ISARMED(tp, 2039 TCPT_PERSIST) == 0) 2040 TCP_TIMER_ARM(tp, TCPT_REXMT, 2041 tp->t_rxtcur); 2042 2043 sowwakeup(so); 2044 if (so->so_snd.sb_cc) { 2045 KERNEL_LOCK(1, NULL); 2046 (void) tcp_output(tp); 2047 KERNEL_UNLOCK_ONE(NULL); 2048 } 2049 if (tcp_saveti) 2050 m_freem(tcp_saveti); 2051 return; 2052 } 2053 } else if (th->th_ack == tp->snd_una && 2054 TAILQ_FIRST(&tp->segq) == NULL && 2055 tlen <= sbspace(&so->so_rcv)) { 2056 int newsize = 0; /* automatic sockbuf scaling */ 2057 2058 /* 2059 * this is a pure, in-sequence data packet 2060 * with nothing on the reassembly queue and 2061 * we have enough buffer space to take it. 2062 */ 2063 tp->rcv_nxt += tlen; 2064 tcps = TCP_STAT_GETREF(); 2065 tcps[TCP_STAT_PREDDAT]++; 2066 tcps[TCP_STAT_RCVPACK]++; 2067 tcps[TCP_STAT_RCVBYTE] += tlen; 2068 TCP_STAT_PUTREF(); 2069 nd6_hint(tp); 2070 2071 /* 2072 * Automatic sizing enables the performance of large buffers 2073 * and most of the efficiency of small ones by only allocating 2074 * space when it is needed. 2075 * 2076 * On the receive side the socket buffer memory is only rarely 2077 * used to any significant extent. This allows us to be much 2078 * more aggressive in scaling the receive socket buffer. For 2079 * the case that the buffer space is actually used to a large 2080 * extent and we run out of kernel memory we can simply drop 2081 * the new segments; TCP on the sender will just retransmit it 2082 * later. Setting the buffer size too big may only consume too 2083 * much kernel memory if the application doesn't read() from 2084 * the socket or packet loss or reordering makes use of the 2085 * reassembly queue. 2086 * 2087 * The criteria to step up the receive buffer one notch are: 2088 * 1. the number of bytes received during the time it takes 2089 * one timestamp to be reflected back to us (the RTT); 2090 * 2. received bytes per RTT is within seven eighth of the 2091 * current socket buffer size; 2092 * 3. receive buffer size has not hit maximal automatic size; 2093 * 2094 * This algorithm does one step per RTT at most and only if 2095 * we receive a bulk stream w/o packet losses or reorderings. 2096 * Shrinking the buffer during idle times is not necessary as 2097 * it doesn't consume any memory when idle. 2098 * 2099 * TODO: Only step up if the application is actually serving 2100 * the buffer to better manage the socket buffer resources. 2101 */ 2102 if (tcp_do_autorcvbuf && 2103 opti.ts_ecr && 2104 (so->so_rcv.sb_flags & SB_AUTOSIZE)) { 2105 if (opti.ts_ecr > tp->rfbuf_ts && 2106 opti.ts_ecr - tp->rfbuf_ts < PR_SLOWHZ) { 2107 if (tp->rfbuf_cnt > 2108 (so->so_rcv.sb_hiwat / 8 * 7) && 2109 so->so_rcv.sb_hiwat < 2110 tcp_autorcvbuf_max) { 2111 newsize = 2112 min(so->so_rcv.sb_hiwat + 2113 tcp_autorcvbuf_inc, 2114 tcp_autorcvbuf_max); 2115 } 2116 /* Start over with next RTT. */ 2117 tp->rfbuf_ts = 0; 2118 tp->rfbuf_cnt = 0; 2119 } else 2120 tp->rfbuf_cnt += tlen; /* add up */ 2121 } 2122 2123 /* 2124 * Drop TCP, IP headers and TCP options then add data 2125 * to socket buffer. 2126 */ 2127 if (so->so_state & SS_CANTRCVMORE) 2128 m_freem(m); 2129 else { 2130 /* 2131 * Set new socket buffer size. 2132 * Give up when limit is reached. 2133 */ 2134 if (newsize) 2135 if (!sbreserve(&so->so_rcv, 2136 newsize, so)) 2137 so->so_rcv.sb_flags &= ~SB_AUTOSIZE; 2138 m_adj(m, toff + off); 2139 sbappendstream(&so->so_rcv, m); 2140 } 2141 sorwakeup(so); 2142 tcp_setup_ack(tp, th); 2143 if (tp->t_flags & TF_ACKNOW) { 2144 KERNEL_LOCK(1, NULL); 2145 (void) tcp_output(tp); 2146 KERNEL_UNLOCK_ONE(NULL); 2147 } 2148 if (tcp_saveti) 2149 m_freem(tcp_saveti); 2150 return; 2151 } 2152 } 2153 2154 /* 2155 * Compute mbuf offset to TCP data segment. 2156 */ 2157 hdroptlen = toff + off; 2158 2159 /* 2160 * Calculate amount of space in receive window, 2161 * and then do TCP input processing. 2162 * Receive window is amount of space in rcv queue, 2163 * but not less than advertised window. 2164 */ 2165 { int win; 2166 2167 win = sbspace(&so->so_rcv); 2168 if (win < 0) 2169 win = 0; 2170 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 2171 } 2172 2173 /* Reset receive buffer auto scaling when not in bulk receive mode. */ 2174 tp->rfbuf_ts = 0; 2175 tp->rfbuf_cnt = 0; 2176 2177 switch (tp->t_state) { 2178 /* 2179 * If the state is SYN_SENT: 2180 * if seg contains an ACK, but not for our SYN, drop the input. 2181 * if seg contains a RST, then drop the connection. 2182 * if seg does not contain SYN, then drop it. 2183 * Otherwise this is an acceptable SYN segment 2184 * initialize tp->rcv_nxt and tp->irs 2185 * if seg contains ack then advance tp->snd_una 2186 * if seg contains a ECE and ECN support is enabled, the stream 2187 * is ECN capable. 2188 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 2189 * arrange for segment to be acked (eventually) 2190 * continue processing rest of data/controls, beginning with URG 2191 */ 2192 case TCPS_SYN_SENT: 2193 if ((tiflags & TH_ACK) && 2194 (SEQ_LEQ(th->th_ack, tp->iss) || 2195 SEQ_GT(th->th_ack, tp->snd_max))) 2196 goto dropwithreset; 2197 if (tiflags & TH_RST) { 2198 if (tiflags & TH_ACK) 2199 tp = tcp_drop(tp, ECONNREFUSED); 2200 goto drop; 2201 } 2202 if ((tiflags & TH_SYN) == 0) 2203 goto drop; 2204 if (tiflags & TH_ACK) { 2205 tp->snd_una = th->th_ack; 2206 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2207 tp->snd_nxt = tp->snd_una; 2208 if (SEQ_LT(tp->snd_high, tp->snd_una)) 2209 tp->snd_high = tp->snd_una; 2210 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2211 2212 if ((tiflags & TH_ECE) && tcp_do_ecn) { 2213 tp->t_flags |= TF_ECN_PERMIT; 2214 TCP_STATINC(TCP_STAT_ECN_SHS); 2215 } 2216 2217 } 2218 tp->irs = th->th_seq; 2219 tcp_rcvseqinit(tp); 2220 tp->t_flags |= TF_ACKNOW; 2221 tcp_mss_from_peer(tp, opti.maxseg); 2222 2223 /* 2224 * Initialize the initial congestion window. If we 2225 * had to retransmit the SYN, we must initialize cwnd 2226 * to 1 segment (i.e. the Loss Window). 2227 */ 2228 if (tp->t_flags & TF_SYN_REXMT) 2229 tp->snd_cwnd = tp->t_peermss; 2230 else { 2231 int ss = tcp_init_win; 2232 #ifdef INET 2233 if (inp != NULL && in_localaddr(inp->inp_faddr)) 2234 ss = tcp_init_win_local; 2235 #endif 2236 #ifdef INET6 2237 if (in6p != NULL && in6_localaddr(&in6p->in6p_faddr)) 2238 ss = tcp_init_win_local; 2239 #endif 2240 tp->snd_cwnd = TCP_INITIAL_WINDOW(ss, tp->t_peermss); 2241 } 2242 2243 tcp_rmx_rtt(tp); 2244 if (tiflags & TH_ACK) { 2245 TCP_STATINC(TCP_STAT_CONNECTS); 2246 /* 2247 * move tcp_established before soisconnected 2248 * because upcall handler can drive tcp_output 2249 * functionality. 2250 * XXX we might call soisconnected at the end of 2251 * all processing 2252 */ 2253 tcp_established(tp); 2254 soisconnected(so); 2255 /* Do window scaling on this connection? */ 2256 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2257 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2258 tp->snd_scale = tp->requested_s_scale; 2259 tp->rcv_scale = tp->request_r_scale; 2260 } 2261 TCP_REASS_LOCK(tp); 2262 (void) tcp_reass(tp, NULL, NULL, &tlen); 2263 /* 2264 * if we didn't have to retransmit the SYN, 2265 * use its rtt as our initial srtt & rtt var. 2266 */ 2267 if (tp->t_rtttime) 2268 tcp_xmit_timer(tp, tcp_now - tp->t_rtttime); 2269 } else 2270 tp->t_state = TCPS_SYN_RECEIVED; 2271 2272 /* 2273 * Advance th->th_seq to correspond to first data byte. 2274 * If data, trim to stay within window, 2275 * dropping FIN if necessary. 2276 */ 2277 th->th_seq++; 2278 if (tlen > tp->rcv_wnd) { 2279 todrop = tlen - tp->rcv_wnd; 2280 m_adj(m, -todrop); 2281 tlen = tp->rcv_wnd; 2282 tiflags &= ~TH_FIN; 2283 tcps = TCP_STAT_GETREF(); 2284 tcps[TCP_STAT_RCVPACKAFTERWIN]++; 2285 tcps[TCP_STAT_RCVBYTEAFTERWIN] += todrop; 2286 TCP_STAT_PUTREF(); 2287 } 2288 tp->snd_wl1 = th->th_seq - 1; 2289 tp->rcv_up = th->th_seq; 2290 goto step6; 2291 2292 /* 2293 * If the state is SYN_RECEIVED: 2294 * If seg contains an ACK, but not for our SYN, drop the input 2295 * and generate an RST. See page 36, rfc793 2296 */ 2297 case TCPS_SYN_RECEIVED: 2298 if ((tiflags & TH_ACK) && 2299 (SEQ_LEQ(th->th_ack, tp->iss) || 2300 SEQ_GT(th->th_ack, tp->snd_max))) 2301 goto dropwithreset; 2302 break; 2303 } 2304 2305 /* 2306 * States other than LISTEN or SYN_SENT. 2307 * First check timestamp, if present. 2308 * Then check that at least some bytes of segment are within 2309 * receive window. If segment begins before rcv_nxt, 2310 * drop leading data (and SYN); if nothing left, just ack. 2311 * 2312 * RFC 1323 PAWS: If we have a timestamp reply on this segment 2313 * and it's less than ts_recent, drop it. 2314 */ 2315 if (opti.ts_present && (tiflags & TH_RST) == 0 && tp->ts_recent && 2316 TSTMP_LT(opti.ts_val, tp->ts_recent)) { 2317 2318 /* Check to see if ts_recent is over 24 days old. */ 2319 if (tcp_now - tp->ts_recent_age > TCP_PAWS_IDLE) { 2320 /* 2321 * Invalidate ts_recent. If this segment updates 2322 * ts_recent, the age will be reset later and ts_recent 2323 * will get a valid value. If it does not, setting 2324 * ts_recent to zero will at least satisfy the 2325 * requirement that zero be placed in the timestamp 2326 * echo reply when ts_recent isn't valid. The 2327 * age isn't reset until we get a valid ts_recent 2328 * because we don't want out-of-order segments to be 2329 * dropped when ts_recent is old. 2330 */ 2331 tp->ts_recent = 0; 2332 } else { 2333 tcps = TCP_STAT_GETREF(); 2334 tcps[TCP_STAT_RCVDUPPACK]++; 2335 tcps[TCP_STAT_RCVDUPBYTE] += tlen; 2336 tcps[TCP_STAT_PAWSDROP]++; 2337 TCP_STAT_PUTREF(); 2338 tcp_new_dsack(tp, th->th_seq, tlen); 2339 goto dropafterack; 2340 } 2341 } 2342 2343 todrop = tp->rcv_nxt - th->th_seq; 2344 dupseg = false; 2345 if (todrop > 0) { 2346 if (tiflags & TH_SYN) { 2347 tiflags &= ~TH_SYN; 2348 th->th_seq++; 2349 if (th->th_urp > 1) 2350 th->th_urp--; 2351 else { 2352 tiflags &= ~TH_URG; 2353 th->th_urp = 0; 2354 } 2355 todrop--; 2356 } 2357 if (todrop > tlen || 2358 (todrop == tlen && (tiflags & TH_FIN) == 0)) { 2359 /* 2360 * Any valid FIN or RST must be to the left of the 2361 * window. At this point the FIN or RST must be a 2362 * duplicate or out of sequence; drop it. 2363 */ 2364 if (tiflags & TH_RST) 2365 goto drop; 2366 tiflags &= ~(TH_FIN|TH_RST); 2367 /* 2368 * Send an ACK to resynchronize and drop any data. 2369 * But keep on processing for RST or ACK. 2370 */ 2371 tp->t_flags |= TF_ACKNOW; 2372 todrop = tlen; 2373 dupseg = true; 2374 tcps = TCP_STAT_GETREF(); 2375 tcps[TCP_STAT_RCVDUPPACK]++; 2376 tcps[TCP_STAT_RCVDUPBYTE] += todrop; 2377 TCP_STAT_PUTREF(); 2378 } else if ((tiflags & TH_RST) && 2379 th->th_seq != tp->rcv_nxt) { 2380 /* 2381 * Test for reset before adjusting the sequence 2382 * number for overlapping data. 2383 */ 2384 goto dropafterack_ratelim; 2385 } else { 2386 tcps = TCP_STAT_GETREF(); 2387 tcps[TCP_STAT_RCVPARTDUPPACK]++; 2388 tcps[TCP_STAT_RCVPARTDUPBYTE] += todrop; 2389 TCP_STAT_PUTREF(); 2390 } 2391 tcp_new_dsack(tp, th->th_seq, todrop); 2392 hdroptlen += todrop; /*drop from head afterwards*/ 2393 th->th_seq += todrop; 2394 tlen -= todrop; 2395 if (th->th_urp > todrop) 2396 th->th_urp -= todrop; 2397 else { 2398 tiflags &= ~TH_URG; 2399 th->th_urp = 0; 2400 } 2401 } 2402 2403 /* 2404 * If new data are received on a connection after the 2405 * user processes are gone, then RST the other end. 2406 */ 2407 if ((so->so_state & SS_NOFDREF) && 2408 tp->t_state > TCPS_CLOSE_WAIT && tlen) { 2409 tp = tcp_close(tp); 2410 TCP_STATINC(TCP_STAT_RCVAFTERCLOSE); 2411 goto dropwithreset; 2412 } 2413 2414 /* 2415 * If segment ends after window, drop trailing data 2416 * (and PUSH and FIN); if nothing left, just ACK. 2417 */ 2418 todrop = (th->th_seq + tlen) - (tp->rcv_nxt+tp->rcv_wnd); 2419 if (todrop > 0) { 2420 TCP_STATINC(TCP_STAT_RCVPACKAFTERWIN); 2421 if (todrop >= tlen) { 2422 /* 2423 * The segment actually starts after the window. 2424 * th->th_seq + tlen - tp->rcv_nxt - tp->rcv_wnd >= tlen 2425 * th->th_seq - tp->rcv_nxt - tp->rcv_wnd >= 0 2426 * th->th_seq >= tp->rcv_nxt + tp->rcv_wnd 2427 */ 2428 TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, tlen); 2429 /* 2430 * If a new connection request is received 2431 * while in TIME_WAIT, drop the old connection 2432 * and start over if the sequence numbers 2433 * are above the previous ones. 2434 * 2435 * NOTE: We will checksum the packet again, and 2436 * so we need to put the header fields back into 2437 * network order! 2438 * XXX This kind of sucks, but we don't expect 2439 * XXX this to happen very often, so maybe it 2440 * XXX doesn't matter so much. 2441 */ 2442 if (tiflags & TH_SYN && 2443 tp->t_state == TCPS_TIME_WAIT && 2444 SEQ_GT(th->th_seq, tp->rcv_nxt)) { 2445 tp = tcp_close(tp); 2446 tcp_fields_to_net(th); 2447 goto findpcb; 2448 } 2449 /* 2450 * If window is closed can only take segments at 2451 * window edge, and have to drop data and PUSH from 2452 * incoming segments. Continue processing, but 2453 * remember to ack. Otherwise, drop segment 2454 * and (if not RST) ack. 2455 */ 2456 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 2457 tp->t_flags |= TF_ACKNOW; 2458 TCP_STATINC(TCP_STAT_RCVWINPROBE); 2459 } else 2460 goto dropafterack; 2461 } else 2462 TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, todrop); 2463 m_adj(m, -todrop); 2464 tlen -= todrop; 2465 tiflags &= ~(TH_PUSH|TH_FIN); 2466 } 2467 2468 /* 2469 * If last ACK falls within this segment's sequence numbers, 2470 * record the timestamp. 2471 * NOTE: 2472 * 1) That the test incorporates suggestions from the latest 2473 * proposal of the tcplw (at) cray.com list (Braden 1993/04/26). 2474 * 2) That updating only on newer timestamps interferes with 2475 * our earlier PAWS tests, so this check should be solely 2476 * predicated on the sequence space of this segment. 2477 * 3) That we modify the segment boundary check to be 2478 * Last.ACK.Sent <= SEG.SEQ + SEG.Len 2479 * instead of RFC1323's 2480 * Last.ACK.Sent < SEG.SEQ + SEG.Len, 2481 * This modified check allows us to overcome RFC1323's 2482 * limitations as described in Stevens TCP/IP Illustrated 2483 * Vol. 2 p.869. In such cases, we can still calculate the 2484 * RTT correctly when RCV.NXT == Last.ACK.Sent. 2485 */ 2486 if (opti.ts_present && 2487 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 2488 SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen + 2489 ((tiflags & (TH_SYN|TH_FIN)) != 0))) { 2490 tp->ts_recent_age = tcp_now; 2491 tp->ts_recent = opti.ts_val; 2492 } 2493 2494 /* 2495 * If the RST bit is set examine the state: 2496 * SYN_RECEIVED STATE: 2497 * If passive open, return to LISTEN state. 2498 * If active open, inform user that connection was refused. 2499 * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES: 2500 * Inform user that connection was reset, and close tcb. 2501 * CLOSING, LAST_ACK, TIME_WAIT STATES 2502 * Close the tcb. 2503 */ 2504 if (tiflags & TH_RST) { 2505 if (th->th_seq != tp->rcv_nxt) 2506 goto dropafterack_ratelim; 2507 2508 switch (tp->t_state) { 2509 case TCPS_SYN_RECEIVED: 2510 so->so_error = ECONNREFUSED; 2511 goto close; 2512 2513 case TCPS_ESTABLISHED: 2514 case TCPS_FIN_WAIT_1: 2515 case TCPS_FIN_WAIT_2: 2516 case TCPS_CLOSE_WAIT: 2517 so->so_error = ECONNRESET; 2518 close: 2519 tp->t_state = TCPS_CLOSED; 2520 TCP_STATINC(TCP_STAT_DROPS); 2521 tp = tcp_close(tp); 2522 goto drop; 2523 2524 case TCPS_CLOSING: 2525 case TCPS_LAST_ACK: 2526 case TCPS_TIME_WAIT: 2527 tp = tcp_close(tp); 2528 goto drop; 2529 } 2530 } 2531 2532 /* 2533 * Since we've covered the SYN-SENT and SYN-RECEIVED states above 2534 * we must be in a synchronized state. RFC791 states (under RST 2535 * generation) that any unacceptable segment (an out-of-order SYN 2536 * qualifies) received in a synchronized state must elicit only an 2537 * empty acknowledgment segment ... and the connection remains in 2538 * the same state. 2539 */ 2540 if (tiflags & TH_SYN) { 2541 if (tp->rcv_nxt == th->th_seq) { 2542 tcp_respond(tp, m, m, th, (tcp_seq)0, th->th_ack - 1, 2543 TH_ACK); 2544 if (tcp_saveti) 2545 m_freem(tcp_saveti); 2546 return; 2547 } 2548 2549 goto dropafterack_ratelim; 2550 } 2551 2552 /* 2553 * If the ACK bit is off we drop the segment and return. 2554 */ 2555 if ((tiflags & TH_ACK) == 0) { 2556 if (tp->t_flags & TF_ACKNOW) 2557 goto dropafterack; 2558 else 2559 goto drop; 2560 } 2561 2562 /* 2563 * Ack processing. 2564 */ 2565 switch (tp->t_state) { 2566 2567 /* 2568 * In SYN_RECEIVED state if the ack ACKs our SYN then enter 2569 * ESTABLISHED state and continue processing, otherwise 2570 * send an RST. 2571 */ 2572 case TCPS_SYN_RECEIVED: 2573 if (SEQ_GT(tp->snd_una, th->th_ack) || 2574 SEQ_GT(th->th_ack, tp->snd_max)) 2575 goto dropwithreset; 2576 TCP_STATINC(TCP_STAT_CONNECTS); 2577 soisconnected(so); 2578 tcp_established(tp); 2579 /* Do window scaling? */ 2580 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2581 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2582 tp->snd_scale = tp->requested_s_scale; 2583 tp->rcv_scale = tp->request_r_scale; 2584 } 2585 TCP_REASS_LOCK(tp); 2586 (void) tcp_reass(tp, NULL, NULL, &tlen); 2587 tp->snd_wl1 = th->th_seq - 1; 2588 /* fall into ... */ 2589 2590 /* 2591 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 2592 * ACKs. If the ack is in the range 2593 * tp->snd_una < th->th_ack <= tp->snd_max 2594 * then advance tp->snd_una to th->th_ack and drop 2595 * data from the retransmission queue. If this ACK reflects 2596 * more up to date window information we update our window information. 2597 */ 2598 case TCPS_ESTABLISHED: 2599 case TCPS_FIN_WAIT_1: 2600 case TCPS_FIN_WAIT_2: 2601 case TCPS_CLOSE_WAIT: 2602 case TCPS_CLOSING: 2603 case TCPS_LAST_ACK: 2604 case TCPS_TIME_WAIT: 2605 2606 if (SEQ_LEQ(th->th_ack, tp->snd_una)) { 2607 if (tlen == 0 && !dupseg && tiwin == tp->snd_wnd) { 2608 TCP_STATINC(TCP_STAT_RCVDUPACK); 2609 /* 2610 * If we have outstanding data (other than 2611 * a window probe), this is a completely 2612 * duplicate ack (ie, window info didn't 2613 * change), the ack is the biggest we've 2614 * seen and we've seen exactly our rexmt 2615 * threshhold of them, assume a packet 2616 * has been dropped and retransmit it. 2617 * Kludge snd_nxt & the congestion 2618 * window so we send only this one 2619 * packet. 2620 */ 2621 if (TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 || 2622 th->th_ack != tp->snd_una) 2623 tp->t_dupacks = 0; 2624 else if (tp->t_partialacks < 0 && 2625 (++tp->t_dupacks == tcprexmtthresh || 2626 TCP_FACK_FASTRECOV(tp))) { 2627 /* 2628 * Do the fast retransmit, and adjust 2629 * congestion control paramenters. 2630 */ 2631 if (tp->t_congctl->fast_retransmit(tp, th)) { 2632 /* False fast retransmit */ 2633 break; 2634 } else 2635 goto drop; 2636 } else if (tp->t_dupacks > tcprexmtthresh) { 2637 tp->snd_cwnd += tp->t_segsz; 2638 KERNEL_LOCK(1, NULL); 2639 (void) tcp_output(tp); 2640 KERNEL_UNLOCK_ONE(NULL); 2641 goto drop; 2642 } 2643 } else { 2644 /* 2645 * If the ack appears to be very old, only 2646 * allow data that is in-sequence. This 2647 * makes it somewhat more difficult to insert 2648 * forged data by guessing sequence numbers. 2649 * Sent an ack to try to update the send 2650 * sequence number on the other side. 2651 */ 2652 if (tlen && th->th_seq != tp->rcv_nxt && 2653 SEQ_LT(th->th_ack, 2654 tp->snd_una - tp->max_sndwnd)) 2655 goto dropafterack; 2656 } 2657 break; 2658 } 2659 /* 2660 * If the congestion window was inflated to account 2661 * for the other side's cached packets, retract it. 2662 */ 2663 tp->t_congctl->fast_retransmit_newack(tp, th); 2664 2665 if (SEQ_GT(th->th_ack, tp->snd_max)) { 2666 TCP_STATINC(TCP_STAT_RCVACKTOOMUCH); 2667 goto dropafterack; 2668 } 2669 acked = th->th_ack - tp->snd_una; 2670 tcps = TCP_STAT_GETREF(); 2671 tcps[TCP_STAT_RCVACKPACK]++; 2672 tcps[TCP_STAT_RCVACKBYTE] += acked; 2673 TCP_STAT_PUTREF(); 2674 2675 /* 2676 * If we have a timestamp reply, update smoothed 2677 * round trip time. If no timestamp is present but 2678 * transmit timer is running and timed sequence 2679 * number was acked, update smoothed round trip time. 2680 * Since we now have an rtt measurement, cancel the 2681 * timer backoff (cf., Phil Karn's retransmit alg.). 2682 * Recompute the initial retransmit timer. 2683 */ 2684 if (ts_rtt) 2685 tcp_xmit_timer(tp, ts_rtt - 1); 2686 else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) 2687 tcp_xmit_timer(tp, tcp_now - tp->t_rtttime); 2688 2689 /* 2690 * If all outstanding data is acked, stop retransmit 2691 * timer and remember to restart (more output or persist). 2692 * If there is more data to be acked, restart retransmit 2693 * timer, using current (possibly backed-off) value. 2694 */ 2695 if (th->th_ack == tp->snd_max) { 2696 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2697 needoutput = 1; 2698 } else if (TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) 2699 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 2700 2701 /* 2702 * New data has been acked, adjust the congestion window. 2703 */ 2704 tp->t_congctl->newack(tp, th); 2705 2706 nd6_hint(tp); 2707 if (acked > so->so_snd.sb_cc) { 2708 tp->snd_wnd -= so->so_snd.sb_cc; 2709 sbdrop(&so->so_snd, (int)so->so_snd.sb_cc); 2710 ourfinisacked = 1; 2711 } else { 2712 if (acked > (tp->t_lastoff - tp->t_inoff)) 2713 tp->t_lastm = NULL; 2714 sbdrop(&so->so_snd, acked); 2715 tp->t_lastoff -= acked; 2716 tp->snd_wnd -= acked; 2717 ourfinisacked = 0; 2718 } 2719 sowwakeup(so); 2720 2721 icmp_check(tp, th, acked); 2722 2723 tp->snd_una = th->th_ack; 2724 if (SEQ_GT(tp->snd_una, tp->snd_fack)) 2725 tp->snd_fack = tp->snd_una; 2726 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2727 tp->snd_nxt = tp->snd_una; 2728 if (SEQ_LT(tp->snd_high, tp->snd_una)) 2729 tp->snd_high = tp->snd_una; 2730 2731 switch (tp->t_state) { 2732 2733 /* 2734 * In FIN_WAIT_1 STATE in addition to the processing 2735 * for the ESTABLISHED state if our FIN is now acknowledged 2736 * then enter FIN_WAIT_2. 2737 */ 2738 case TCPS_FIN_WAIT_1: 2739 if (ourfinisacked) { 2740 /* 2741 * If we can't receive any more 2742 * data, then closing user can proceed. 2743 * Starting the timer is contrary to the 2744 * specification, but if we don't get a FIN 2745 * we'll hang forever. 2746 */ 2747 if (so->so_state & SS_CANTRCVMORE) { 2748 soisdisconnected(so); 2749 if (tp->t_maxidle > 0) 2750 TCP_TIMER_ARM(tp, TCPT_2MSL, 2751 tp->t_maxidle); 2752 } 2753 tp->t_state = TCPS_FIN_WAIT_2; 2754 } 2755 break; 2756 2757 /* 2758 * In CLOSING STATE in addition to the processing for 2759 * the ESTABLISHED state if the ACK acknowledges our FIN 2760 * then enter the TIME-WAIT state, otherwise ignore 2761 * the segment. 2762 */ 2763 case TCPS_CLOSING: 2764 if (ourfinisacked) { 2765 tp->t_state = TCPS_TIME_WAIT; 2766 tcp_canceltimers(tp); 2767 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * tp->t_msl); 2768 soisdisconnected(so); 2769 } 2770 break; 2771 2772 /* 2773 * In LAST_ACK, we may still be waiting for data to drain 2774 * and/or to be acked, as well as for the ack of our FIN. 2775 * If our FIN is now acknowledged, delete the TCB, 2776 * enter the closed state and return. 2777 */ 2778 case TCPS_LAST_ACK: 2779 if (ourfinisacked) { 2780 tp = tcp_close(tp); 2781 goto drop; 2782 } 2783 break; 2784 2785 /* 2786 * In TIME_WAIT state the only thing that should arrive 2787 * is a retransmission of the remote FIN. Acknowledge 2788 * it and restart the finack timer. 2789 */ 2790 case TCPS_TIME_WAIT: 2791 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * tp->t_msl); 2792 goto dropafterack; 2793 } 2794 } 2795 2796 step6: 2797 /* 2798 * Update window information. 2799 * Don't look at window if no ACK: TAC's send garbage on first SYN. 2800 */ 2801 if ((tiflags & TH_ACK) && (SEQ_LT(tp->snd_wl1, th->th_seq) || 2802 (tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) || 2803 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) { 2804 /* keep track of pure window updates */ 2805 if (tlen == 0 && 2806 tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) 2807 TCP_STATINC(TCP_STAT_RCVWINUPD); 2808 tp->snd_wnd = tiwin; 2809 tp->snd_wl1 = th->th_seq; 2810 tp->snd_wl2 = th->th_ack; 2811 if (tp->snd_wnd > tp->max_sndwnd) 2812 tp->max_sndwnd = tp->snd_wnd; 2813 needoutput = 1; 2814 } 2815 2816 /* 2817 * Process segments with URG. 2818 */ 2819 if ((tiflags & TH_URG) && th->th_urp && 2820 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2821 /* 2822 * This is a kludge, but if we receive and accept 2823 * random urgent pointers, we'll crash in 2824 * soreceive. It's hard to imagine someone 2825 * actually wanting to send this much urgent data. 2826 */ 2827 if (th->th_urp + so->so_rcv.sb_cc > sb_max) { 2828 th->th_urp = 0; /* XXX */ 2829 tiflags &= ~TH_URG; /* XXX */ 2830 goto dodata; /* XXX */ 2831 } 2832 /* 2833 * If this segment advances the known urgent pointer, 2834 * then mark the data stream. This should not happen 2835 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 2836 * a FIN has been received from the remote side. 2837 * In these states we ignore the URG. 2838 * 2839 * According to RFC961 (Assigned Protocols), 2840 * the urgent pointer points to the last octet 2841 * of urgent data. We continue, however, 2842 * to consider it to indicate the first octet 2843 * of data past the urgent section as the original 2844 * spec states (in one of two places). 2845 */ 2846 if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) { 2847 tp->rcv_up = th->th_seq + th->th_urp; 2848 so->so_oobmark = so->so_rcv.sb_cc + 2849 (tp->rcv_up - tp->rcv_nxt) - 1; 2850 if (so->so_oobmark == 0) 2851 so->so_state |= SS_RCVATMARK; 2852 sohasoutofband(so); 2853 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); 2854 } 2855 /* 2856 * Remove out of band data so doesn't get presented to user. 2857 * This can happen independent of advancing the URG pointer, 2858 * but if two URG's are pending at once, some out-of-band 2859 * data may creep in... ick. 2860 */ 2861 if (th->th_urp <= (u_int16_t) tlen 2862 #ifdef SO_OOBINLINE 2863 && (so->so_options & SO_OOBINLINE) == 0 2864 #endif 2865 ) 2866 tcp_pulloutofband(so, th, m, hdroptlen); 2867 } else 2868 /* 2869 * If no out of band data is expected, 2870 * pull receive urgent pointer along 2871 * with the receive window. 2872 */ 2873 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) 2874 tp->rcv_up = tp->rcv_nxt; 2875 dodata: /* XXX */ 2876 2877 /* 2878 * Process the segment text, merging it into the TCP sequencing queue, 2879 * and arranging for acknowledgement of receipt if necessary. 2880 * This process logically involves adjusting tp->rcv_wnd as data 2881 * is presented to the user (this happens in tcp_usrreq.c, 2882 * tcp_rcvd()). If a FIN has already been received on this 2883 * connection then we just ignore the text. 2884 */ 2885 if ((tlen || (tiflags & TH_FIN)) && 2886 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2887 /* 2888 * Insert segment ti into reassembly queue of tcp with 2889 * control block tp. Return TH_FIN if reassembly now includes 2890 * a segment with FIN. The macro form does the common case 2891 * inline (segment is the next to be received on an 2892 * established connection, and the queue is empty), 2893 * avoiding linkage into and removal from the queue and 2894 * repetition of various conversions. 2895 * Set DELACK for segments received in order, but ack 2896 * immediately when segments are out of order 2897 * (so fast retransmit can work). 2898 */ 2899 /* NOTE: this was TCP_REASS() macro, but used only once */ 2900 TCP_REASS_LOCK(tp); 2901 if (th->th_seq == tp->rcv_nxt && 2902 TAILQ_FIRST(&tp->segq) == NULL && 2903 tp->t_state == TCPS_ESTABLISHED) { 2904 tcp_setup_ack(tp, th); 2905 tp->rcv_nxt += tlen; 2906 tiflags = th->th_flags & TH_FIN; 2907 tcps = TCP_STAT_GETREF(); 2908 tcps[TCP_STAT_RCVPACK]++; 2909 tcps[TCP_STAT_RCVBYTE] += tlen; 2910 TCP_STAT_PUTREF(); 2911 nd6_hint(tp); 2912 if (so->so_state & SS_CANTRCVMORE) 2913 m_freem(m); 2914 else { 2915 m_adj(m, hdroptlen); 2916 sbappendstream(&(so)->so_rcv, m); 2917 } 2918 TCP_REASS_UNLOCK(tp); 2919 sorwakeup(so); 2920 } else { 2921 m_adj(m, hdroptlen); 2922 tiflags = tcp_reass(tp, th, m, &tlen); 2923 tp->t_flags |= TF_ACKNOW; 2924 } 2925 2926 /* 2927 * Note the amount of data that peer has sent into 2928 * our window, in order to estimate the sender's 2929 * buffer size. 2930 */ 2931 len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); 2932 } else { 2933 m_freem(m); 2934 m = NULL; 2935 tiflags &= ~TH_FIN; 2936 } 2937 2938 /* 2939 * If FIN is received ACK the FIN and let the user know 2940 * that the connection is closing. Ignore a FIN received before 2941 * the connection is fully established. 2942 */ 2943 if ((tiflags & TH_FIN) && TCPS_HAVEESTABLISHED(tp->t_state)) { 2944 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2945 socantrcvmore(so); 2946 tp->t_flags |= TF_ACKNOW; 2947 tp->rcv_nxt++; 2948 } 2949 switch (tp->t_state) { 2950 2951 /* 2952 * In ESTABLISHED STATE enter the CLOSE_WAIT state. 2953 */ 2954 case TCPS_ESTABLISHED: 2955 tp->t_state = TCPS_CLOSE_WAIT; 2956 break; 2957 2958 /* 2959 * If still in FIN_WAIT_1 STATE FIN has not been acked so 2960 * enter the CLOSING state. 2961 */ 2962 case TCPS_FIN_WAIT_1: 2963 tp->t_state = TCPS_CLOSING; 2964 break; 2965 2966 /* 2967 * In FIN_WAIT_2 state enter the TIME_WAIT state, 2968 * starting the time-wait timer, turning off the other 2969 * standard timers. 2970 */ 2971 case TCPS_FIN_WAIT_2: 2972 tp->t_state = TCPS_TIME_WAIT; 2973 tcp_canceltimers(tp); 2974 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * tp->t_msl); 2975 soisdisconnected(so); 2976 break; 2977 2978 /* 2979 * In TIME_WAIT state restart the 2 MSL time_wait timer. 2980 */ 2981 case TCPS_TIME_WAIT: 2982 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * tp->t_msl); 2983 break; 2984 } 2985 } 2986 #ifdef TCP_DEBUG 2987 if (so->so_options & SO_DEBUG) 2988 tcp_trace(TA_INPUT, ostate, tp, tcp_saveti, 0); 2989 #endif 2990 2991 /* 2992 * Return any desired output. 2993 */ 2994 if (needoutput || (tp->t_flags & TF_ACKNOW)) { 2995 KERNEL_LOCK(1, NULL); 2996 (void) tcp_output(tp); 2997 KERNEL_UNLOCK_ONE(NULL); 2998 } 2999 if (tcp_saveti) 3000 m_freem(tcp_saveti); 3001 3002 if (tp->t_state == TCPS_TIME_WAIT 3003 && (so->so_state & SS_NOFDREF) 3004 && (tp->t_inpcb || af != AF_INET) 3005 && (tp->t_in6pcb || af != AF_INET6) 3006 && ((af == AF_INET ? tcp4_vtw_enable : tcp6_vtw_enable) & 1) != 0 3007 && TAILQ_EMPTY(&tp->segq) 3008 && vtw_add(af, tp)) { 3009 ; 3010 } 3011 return; 3012 3013 badsyn: 3014 /* 3015 * Received a bad SYN. Increment counters and dropwithreset. 3016 */ 3017 TCP_STATINC(TCP_STAT_BADSYN); 3018 tp = NULL; 3019 goto dropwithreset; 3020 3021 dropafterack: 3022 /* 3023 * Generate an ACK dropping incoming segment if it occupies 3024 * sequence space, where the ACK reflects our state. 3025 */ 3026 if (tiflags & TH_RST) 3027 goto drop; 3028 goto dropafterack2; 3029 3030 dropafterack_ratelim: 3031 /* 3032 * We may want to rate-limit ACKs against SYN/RST attack. 3033 */ 3034 if (ppsratecheck(&tcp_ackdrop_ppslim_last, &tcp_ackdrop_ppslim_count, 3035 tcp_ackdrop_ppslim) == 0) { 3036 /* XXX stat */ 3037 goto drop; 3038 } 3039 /* ...fall into dropafterack2... */ 3040 3041 dropafterack2: 3042 m_freem(m); 3043 tp->t_flags |= TF_ACKNOW; 3044 KERNEL_LOCK(1, NULL); 3045 (void) tcp_output(tp); 3046 KERNEL_UNLOCK_ONE(NULL); 3047 if (tcp_saveti) 3048 m_freem(tcp_saveti); 3049 return; 3050 3051 dropwithreset_ratelim: 3052 /* 3053 * We may want to rate-limit RSTs in certain situations, 3054 * particularly if we are sending an RST in response to 3055 * an attempt to connect to or otherwise communicate with 3056 * a port for which we have no socket. 3057 */ 3058 if (ppsratecheck(&tcp_rst_ppslim_last, &tcp_rst_ppslim_count, 3059 tcp_rst_ppslim) == 0) { 3060 /* XXX stat */ 3061 goto drop; 3062 } 3063 /* ...fall into dropwithreset... */ 3064 3065 dropwithreset: 3066 /* 3067 * Generate a RST, dropping incoming segment. 3068 * Make ACK acceptable to originator of segment. 3069 */ 3070 if (tiflags & TH_RST) 3071 goto drop; 3072 3073 switch (af) { 3074 #ifdef INET6 3075 case AF_INET6: 3076 /* For following calls to tcp_respond */ 3077 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) 3078 goto drop; 3079 break; 3080 #endif /* INET6 */ 3081 case AF_INET: 3082 if (IN_MULTICAST(ip->ip_dst.s_addr) || 3083 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 3084 goto drop; 3085 } 3086 3087 if (tiflags & TH_ACK) 3088 (void)tcp_respond(tp, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 3089 else { 3090 if (tiflags & TH_SYN) 3091 tlen++; 3092 (void)tcp_respond(tp, m, m, th, th->th_seq + tlen, (tcp_seq)0, 3093 TH_RST|TH_ACK); 3094 } 3095 if (tcp_saveti) 3096 m_freem(tcp_saveti); 3097 return; 3098 3099 badcsum: 3100 drop: 3101 /* 3102 * Drop space held by incoming segment and return. 3103 */ 3104 if (tp) { 3105 if (tp->t_inpcb) 3106 so = tp->t_inpcb->inp_socket; 3107 #ifdef INET6 3108 else if (tp->t_in6pcb) 3109 so = tp->t_in6pcb->in6p_socket; 3110 #endif 3111 else 3112 so = NULL; 3113 #ifdef TCP_DEBUG 3114 if (so && (so->so_options & SO_DEBUG) != 0) 3115 tcp_trace(TA_DROP, ostate, tp, tcp_saveti, 0); 3116 #endif 3117 } 3118 if (tcp_saveti) 3119 m_freem(tcp_saveti); 3120 m_freem(m); 3121 return; 3122 } 3123 3124 #ifdef TCP_SIGNATURE 3125 int 3126 tcp_signature_apply(void *fstate, void *data, u_int len) 3127 { 3128 3129 MD5Update(fstate, (u_char *)data, len); 3130 return (0); 3131 } 3132 3133 struct secasvar * 3134 tcp_signature_getsav(struct mbuf *m, struct tcphdr *th) 3135 { 3136 struct ip *ip; 3137 struct ip6_hdr *ip6; 3138 3139 ip = mtod(m, struct ip *); 3140 switch (ip->ip_v) { 3141 case 4: 3142 ip = mtod(m, struct ip *); 3143 ip6 = NULL; 3144 break; 3145 case 6: 3146 ip = NULL; 3147 ip6 = mtod(m, struct ip6_hdr *); 3148 break; 3149 default: 3150 return (NULL); 3151 } 3152 3153 #ifdef IPSEC 3154 if (ipsec_used) { 3155 union sockaddr_union dst; 3156 /* Extract the destination from the IP header in the mbuf. */ 3157 memset(&dst, 0, sizeof(union sockaddr_union)); 3158 if (ip != NULL) { 3159 dst.sa.sa_len = sizeof(struct sockaddr_in); 3160 dst.sa.sa_family = AF_INET; 3161 dst.sin.sin_addr = ip->ip_dst; 3162 } else { 3163 dst.sa.sa_len = sizeof(struct sockaddr_in6); 3164 dst.sa.sa_family = AF_INET6; 3165 dst.sin6.sin6_addr = ip6->ip6_dst; 3166 } 3167 3168 /* 3169 * Look up an SADB entry which matches the address of the peer. 3170 */ 3171 return KEY_ALLOCSA(&dst, IPPROTO_TCP, htonl(TCP_SIG_SPI), 0, 0); 3172 } 3173 return NULL; 3174 #else 3175 if (ip) 3176 return key_allocsa(AF_INET, (void *)&ip->ip_src, 3177 (void *)&ip->ip_dst, IPPROTO_TCP, 3178 htonl(TCP_SIG_SPI), 0, 0); 3179 else 3180 return key_allocsa(AF_INET6, (void *)&ip6->ip6_src, 3181 (void *)&ip6->ip6_dst, IPPROTO_TCP, 3182 htonl(TCP_SIG_SPI), 0, 0); 3183 #endif 3184 } 3185 3186 int 3187 tcp_signature(struct mbuf *m, struct tcphdr *th, int thoff, 3188 struct secasvar *sav, char *sig) 3189 { 3190 MD5_CTX ctx; 3191 struct ip *ip; 3192 struct ipovly *ipovly; 3193 struct ip6_hdr *ip6; 3194 struct ippseudo ippseudo; 3195 struct ip6_hdr_pseudo ip6pseudo; 3196 struct tcphdr th0; 3197 int l, tcphdrlen; 3198 3199 if (sav == NULL) 3200 return (-1); 3201 3202 tcphdrlen = th->th_off * 4; 3203 3204 switch (mtod(m, struct ip *)->ip_v) { 3205 case 4: 3206 ip = mtod(m, struct ip *); 3207 ip6 = NULL; 3208 break; 3209 case 6: 3210 ip = NULL; 3211 ip6 = mtod(m, struct ip6_hdr *); 3212 break; 3213 default: 3214 return (-1); 3215 } 3216 3217 MD5Init(&ctx); 3218 3219 if (ip) { 3220 memset(&ippseudo, 0, sizeof(ippseudo)); 3221 ipovly = (struct ipovly *)ip; 3222 ippseudo.ippseudo_src = ipovly->ih_src; 3223 ippseudo.ippseudo_dst = ipovly->ih_dst; 3224 ippseudo.ippseudo_pad = 0; 3225 ippseudo.ippseudo_p = IPPROTO_TCP; 3226 ippseudo.ippseudo_len = htons(m->m_pkthdr.len - thoff); 3227 MD5Update(&ctx, (char *)&ippseudo, sizeof(ippseudo)); 3228 } else { 3229 memset(&ip6pseudo, 0, sizeof(ip6pseudo)); 3230 ip6pseudo.ip6ph_src = ip6->ip6_src; 3231 in6_clearscope(&ip6pseudo.ip6ph_src); 3232 ip6pseudo.ip6ph_dst = ip6->ip6_dst; 3233 in6_clearscope(&ip6pseudo.ip6ph_dst); 3234 ip6pseudo.ip6ph_len = htons(m->m_pkthdr.len - thoff); 3235 ip6pseudo.ip6ph_nxt = IPPROTO_TCP; 3236 MD5Update(&ctx, (char *)&ip6pseudo, sizeof(ip6pseudo)); 3237 } 3238 3239 th0 = *th; 3240 th0.th_sum = 0; 3241 MD5Update(&ctx, (char *)&th0, sizeof(th0)); 3242 3243 l = m->m_pkthdr.len - thoff - tcphdrlen; 3244 if (l > 0) 3245 m_apply(m, thoff + tcphdrlen, 3246 m->m_pkthdr.len - thoff - tcphdrlen, 3247 tcp_signature_apply, &ctx); 3248 3249 MD5Update(&ctx, _KEYBUF(sav->key_auth), _KEYLEN(sav->key_auth)); 3250 MD5Final(sig, &ctx); 3251 3252 return (0); 3253 } 3254 #endif 3255 3256 /* 3257 * tcp_dooptions: parse and process tcp options. 3258 * 3259 * returns -1 if this segment should be dropped. (eg. wrong signature) 3260 * otherwise returns 0. 3261 */ 3262 3263 static int 3264 tcp_dooptions(struct tcpcb *tp, const u_char *cp, int cnt, 3265 struct tcphdr *th, 3266 struct mbuf *m, int toff, struct tcp_opt_info *oi) 3267 { 3268 u_int16_t mss; 3269 int opt, optlen = 0; 3270 #ifdef TCP_SIGNATURE 3271 void *sigp = NULL; 3272 char sigbuf[TCP_SIGLEN]; 3273 struct secasvar *sav = NULL; 3274 #endif 3275 3276 for (; cp && cnt > 0; cnt -= optlen, cp += optlen) { 3277 opt = cp[0]; 3278 if (opt == TCPOPT_EOL) 3279 break; 3280 if (opt == TCPOPT_NOP) 3281 optlen = 1; 3282 else { 3283 if (cnt < 2) 3284 break; 3285 optlen = cp[1]; 3286 if (optlen < 2 || optlen > cnt) 3287 break; 3288 } 3289 switch (opt) { 3290 3291 default: 3292 continue; 3293 3294 case TCPOPT_MAXSEG: 3295 if (optlen != TCPOLEN_MAXSEG) 3296 continue; 3297 if (!(th->th_flags & TH_SYN)) 3298 continue; 3299 if (TCPS_HAVERCVDSYN(tp->t_state)) 3300 continue; 3301 bcopy(cp + 2, &mss, sizeof(mss)); 3302 oi->maxseg = ntohs(mss); 3303 break; 3304 3305 case TCPOPT_WINDOW: 3306 if (optlen != TCPOLEN_WINDOW) 3307 continue; 3308 if (!(th->th_flags & TH_SYN)) 3309 continue; 3310 if (TCPS_HAVERCVDSYN(tp->t_state)) 3311 continue; 3312 tp->t_flags |= TF_RCVD_SCALE; 3313 tp->requested_s_scale = cp[2]; 3314 if (tp->requested_s_scale > TCP_MAX_WINSHIFT) { 3315 #if 0 /*XXX*/ 3316 char *p; 3317 3318 if (ip) 3319 p = ntohl(ip->ip_src); 3320 #ifdef INET6 3321 else if (ip6) 3322 p = ip6_sprintf(&ip6->ip6_src); 3323 #endif 3324 else 3325 p = "(unknown)"; 3326 log(LOG_ERR, "TCP: invalid wscale %d from %s, " 3327 "assuming %d\n", 3328 tp->requested_s_scale, p, 3329 TCP_MAX_WINSHIFT); 3330 #else 3331 log(LOG_ERR, "TCP: invalid wscale %d, " 3332 "assuming %d\n", 3333 tp->requested_s_scale, 3334 TCP_MAX_WINSHIFT); 3335 #endif 3336 tp->requested_s_scale = TCP_MAX_WINSHIFT; 3337 } 3338 break; 3339 3340 case TCPOPT_TIMESTAMP: 3341 if (optlen != TCPOLEN_TIMESTAMP) 3342 continue; 3343 oi->ts_present = 1; 3344 bcopy(cp + 2, &oi->ts_val, sizeof(oi->ts_val)); 3345 NTOHL(oi->ts_val); 3346 bcopy(cp + 6, &oi->ts_ecr, sizeof(oi->ts_ecr)); 3347 NTOHL(oi->ts_ecr); 3348 3349 if (!(th->th_flags & TH_SYN)) 3350 continue; 3351 if (TCPS_HAVERCVDSYN(tp->t_state)) 3352 continue; 3353 /* 3354 * A timestamp received in a SYN makes 3355 * it ok to send timestamp requests and replies. 3356 */ 3357 tp->t_flags |= TF_RCVD_TSTMP; 3358 tp->ts_recent = oi->ts_val; 3359 tp->ts_recent_age = tcp_now; 3360 break; 3361 3362 case TCPOPT_SACK_PERMITTED: 3363 if (optlen != TCPOLEN_SACK_PERMITTED) 3364 continue; 3365 if (!(th->th_flags & TH_SYN)) 3366 continue; 3367 if (TCPS_HAVERCVDSYN(tp->t_state)) 3368 continue; 3369 if (tcp_do_sack) { 3370 tp->t_flags |= TF_SACK_PERMIT; 3371 tp->t_flags |= TF_WILL_SACK; 3372 } 3373 break; 3374 3375 case TCPOPT_SACK: 3376 tcp_sack_option(tp, th, cp, optlen); 3377 break; 3378 #ifdef TCP_SIGNATURE 3379 case TCPOPT_SIGNATURE: 3380 if (optlen != TCPOLEN_SIGNATURE) 3381 continue; 3382 if (sigp && memcmp(sigp, cp + 2, TCP_SIGLEN)) 3383 return (-1); 3384 3385 sigp = sigbuf; 3386 memcpy(sigbuf, cp + 2, TCP_SIGLEN); 3387 tp->t_flags |= TF_SIGNATURE; 3388 break; 3389 #endif 3390 } 3391 } 3392 3393 #ifndef TCP_SIGNATURE 3394 return 0; 3395 #else 3396 if (tp->t_flags & TF_SIGNATURE) { 3397 3398 sav = tcp_signature_getsav(m, th); 3399 3400 if (sav == NULL && tp->t_state == TCPS_LISTEN) 3401 return (-1); 3402 } 3403 3404 if ((sigp ? TF_SIGNATURE : 0) ^ (tp->t_flags & TF_SIGNATURE)) 3405 goto out; 3406 3407 if (sigp) { 3408 char sig[TCP_SIGLEN]; 3409 3410 tcp_fields_to_net(th); 3411 if (tcp_signature(m, th, toff, sav, sig) < 0) { 3412 tcp_fields_to_host(th); 3413 goto out; 3414 } 3415 tcp_fields_to_host(th); 3416 3417 if (memcmp(sig, sigp, TCP_SIGLEN)) { 3418 TCP_STATINC(TCP_STAT_BADSIG); 3419 goto out; 3420 } else 3421 TCP_STATINC(TCP_STAT_GOODSIG); 3422 3423 key_sa_recordxfer(sav, m); 3424 KEY_FREESAV(&sav); 3425 } 3426 return 0; 3427 out: 3428 if (sav != NULL) 3429 KEY_FREESAV(&sav); 3430 return -1; 3431 #endif 3432 } 3433 3434 /* 3435 * Pull out of band byte out of a segment so 3436 * it doesn't appear in the user's data queue. 3437 * It is still reflected in the segment length for 3438 * sequencing purposes. 3439 */ 3440 void 3441 tcp_pulloutofband(struct socket *so, struct tcphdr *th, 3442 struct mbuf *m, int off) 3443 { 3444 int cnt = off + th->th_urp - 1; 3445 3446 while (cnt >= 0) { 3447 if (m->m_len > cnt) { 3448 char *cp = mtod(m, char *) + cnt; 3449 struct tcpcb *tp = sototcpcb(so); 3450 3451 tp->t_iobc = *cp; 3452 tp->t_oobflags |= TCPOOB_HAVEDATA; 3453 bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); 3454 m->m_len--; 3455 return; 3456 } 3457 cnt -= m->m_len; 3458 m = m->m_next; 3459 if (m == 0) 3460 break; 3461 } 3462 panic("tcp_pulloutofband"); 3463 } 3464 3465 /* 3466 * Collect new round-trip time estimate 3467 * and update averages and current timeout. 3468 * 3469 * rtt is in units of slow ticks (typically 500 ms) -- essentially the 3470 * difference of two timestamps. 3471 */ 3472 void 3473 tcp_xmit_timer(struct tcpcb *tp, uint32_t rtt) 3474 { 3475 int32_t delta; 3476 3477 TCP_STATINC(TCP_STAT_RTTUPDATED); 3478 if (tp->t_srtt != 0) { 3479 /* 3480 * Compute the amount to add to srtt for smoothing, 3481 * *alpha, or 2^(-TCP_RTT_SHIFT). Because 3482 * srtt is stored in 1/32 slow ticks, we conceptually 3483 * shift left 5 bits, subtract srtt to get the 3484 * diference, and then shift right by TCP_RTT_SHIFT 3485 * (3) to obtain 1/8 of the difference. 3486 */ 3487 delta = (rtt << 2) - (tp->t_srtt >> TCP_RTT_SHIFT); 3488 /* 3489 * This can never happen, because delta's lowest 3490 * possible value is 1/8 of t_srtt. But if it does, 3491 * set srtt to some reasonable value, here chosen 3492 * as 1/8 tick. 3493 */ 3494 if ((tp->t_srtt += delta) <= 0) 3495 tp->t_srtt = 1 << 2; 3496 /* 3497 * RFC2988 requires that rttvar be updated first. 3498 * This code is compliant because "delta" is the old 3499 * srtt minus the new observation (scaled). 3500 * 3501 * RFC2988 says: 3502 * rttvar = (1-beta) * rttvar + beta * |srtt-observed| 3503 * 3504 * delta is in units of 1/32 ticks, and has then been 3505 * divided by 8. This is equivalent to being in 1/16s 3506 * units and divided by 4. Subtract from it 1/4 of 3507 * the existing rttvar to form the (signed) amount to 3508 * adjust. 3509 */ 3510 if (delta < 0) 3511 delta = -delta; 3512 delta -= (tp->t_rttvar >> TCP_RTTVAR_SHIFT); 3513 /* 3514 * As with srtt, this should never happen. There is 3515 * no support in RFC2988 for this operation. But 1/4s 3516 * as rttvar when faced with something arguably wrong 3517 * is ok. 3518 */ 3519 if ((tp->t_rttvar += delta) <= 0) 3520 tp->t_rttvar = 1 << 2; 3521 3522 /* 3523 * If srtt exceeds .01 second, ensure we use the 'remote' MSL 3524 * Problem is: it doesn't work. Disabled by defaulting 3525 * tcp_rttlocal to 0; see corresponding code in 3526 * tcp_subr that selects local vs remote in a different way. 3527 * 3528 * The static branch prediction hint here should be removed 3529 * when the rtt estimator is fixed and the rtt_enable code 3530 * is turned back on. 3531 */ 3532 if (__predict_false(tcp_rttlocal) && tcp_msl_enable 3533 && tp->t_srtt > tcp_msl_remote_threshold 3534 && tp->t_msl < tcp_msl_remote) { 3535 tp->t_msl = tcp_msl_remote; 3536 } 3537 } else { 3538 /* 3539 * This is the first measurement. Per RFC2988, 2.2, 3540 * set rtt=R and srtt=R/2. 3541 * For srtt, storage representation is 1/32 ticks, 3542 * so shift left by 5. 3543 * For rttvar, storage representation is 1/16 ticks, 3544 * So shift left by 4, but then right by 1 to halve. 3545 */ 3546 tp->t_srtt = rtt << (TCP_RTT_SHIFT + 2); 3547 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT + 2 - 1); 3548 } 3549 tp->t_rtttime = 0; 3550 tp->t_rxtshift = 0; 3551 3552 /* 3553 * the retransmit should happen at rtt + 4 * rttvar. 3554 * Because of the way we do the smoothing, srtt and rttvar 3555 * will each average +1/2 tick of bias. When we compute 3556 * the retransmit timer, we want 1/2 tick of rounding and 3557 * 1 extra tick because of +-1/2 tick uncertainty in the 3558 * firing of the timer. The bias will give us exactly the 3559 * 1.5 tick we need. But, because the bias is 3560 * statistical, we have to test that we don't drop below 3561 * the minimum feasible timer (which is 2 ticks). 3562 */ 3563 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), 3564 max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX); 3565 3566 /* 3567 * We received an ack for a packet that wasn't retransmitted; 3568 * it is probably safe to discard any error indications we've 3569 * received recently. This isn't quite right, but close enough 3570 * for now (a route might have failed after we sent a segment, 3571 * and the return path might not be symmetrical). 3572 */ 3573 tp->t_softerror = 0; 3574 } 3575 3576 3577 /* 3578 * TCP compressed state engine. Currently used to hold compressed 3579 * state for SYN_RECEIVED. 3580 */ 3581 3582 u_long syn_cache_count; 3583 u_int32_t syn_hash1, syn_hash2; 3584 3585 #define SYN_HASH(sa, sp, dp) \ 3586 ((((sa)->s_addr^syn_hash1)*(((((u_int32_t)(dp))<<16) + \ 3587 ((u_int32_t)(sp)))^syn_hash2))) 3588 #ifndef INET6 3589 #define SYN_HASHALL(hash, src, dst) \ 3590 do { \ 3591 hash = SYN_HASH(&((const struct sockaddr_in *)(src))->sin_addr, \ 3592 ((const struct sockaddr_in *)(src))->sin_port, \ 3593 ((const struct sockaddr_in *)(dst))->sin_port); \ 3594 } while (/*CONSTCOND*/ 0) 3595 #else 3596 #define SYN_HASH6(sa, sp, dp) \ 3597 ((((sa)->s6_addr32[0] ^ (sa)->s6_addr32[3] ^ syn_hash1) * \ 3598 (((((u_int32_t)(dp))<<16) + ((u_int32_t)(sp)))^syn_hash2)) \ 3599 & 0x7fffffff) 3600 3601 #define SYN_HASHALL(hash, src, dst) \ 3602 do { \ 3603 switch ((src)->sa_family) { \ 3604 case AF_INET: \ 3605 hash = SYN_HASH(&((const struct sockaddr_in *)(src))->sin_addr, \ 3606 ((const struct sockaddr_in *)(src))->sin_port, \ 3607 ((const struct sockaddr_in *)(dst))->sin_port); \ 3608 break; \ 3609 case AF_INET6: \ 3610 hash = SYN_HASH6(&((const struct sockaddr_in6 *)(src))->sin6_addr, \ 3611 ((const struct sockaddr_in6 *)(src))->sin6_port, \ 3612 ((const struct sockaddr_in6 *)(dst))->sin6_port); \ 3613 break; \ 3614 default: \ 3615 hash = 0; \ 3616 } \ 3617 } while (/*CONSTCOND*/0) 3618 #endif /* INET6 */ 3619 3620 static struct pool syn_cache_pool; 3621 3622 /* 3623 * We don't estimate RTT with SYNs, so each packet starts with the default 3624 * RTT and each timer step has a fixed timeout value. 3625 */ 3626 #define SYN_CACHE_TIMER_ARM(sc) \ 3627 do { \ 3628 TCPT_RANGESET((sc)->sc_rxtcur, \ 3629 TCPTV_SRTTDFLT * tcp_backoff[(sc)->sc_rxtshift], TCPTV_MIN, \ 3630 TCPTV_REXMTMAX); \ 3631 callout_reset(&(sc)->sc_timer, \ 3632 (sc)->sc_rxtcur * (hz / PR_SLOWHZ), syn_cache_timer, (sc)); \ 3633 } while (/*CONSTCOND*/0) 3634 3635 #define SYN_CACHE_TIMESTAMP(sc) (tcp_now - (sc)->sc_timebase) 3636 3637 static inline void 3638 syn_cache_rm(struct syn_cache *sc) 3639 { 3640 TAILQ_REMOVE(&tcp_syn_cache[sc->sc_bucketidx].sch_bucket, 3641 sc, sc_bucketq); 3642 sc->sc_tp = NULL; 3643 LIST_REMOVE(sc, sc_tpq); 3644 tcp_syn_cache[sc->sc_bucketidx].sch_length--; 3645 callout_stop(&sc->sc_timer); 3646 syn_cache_count--; 3647 } 3648 3649 static inline void 3650 syn_cache_put(struct syn_cache *sc) 3651 { 3652 if (sc->sc_ipopts) 3653 (void) m_free(sc->sc_ipopts); 3654 rtcache_free(&sc->sc_route); 3655 sc->sc_flags |= SCF_DEAD; 3656 if (!callout_invoking(&sc->sc_timer)) 3657 callout_schedule(&(sc)->sc_timer, 1); 3658 } 3659 3660 void 3661 syn_cache_init(void) 3662 { 3663 int i; 3664 3665 pool_init(&syn_cache_pool, sizeof(struct syn_cache), 0, 0, 0, 3666 "synpl", NULL, IPL_SOFTNET); 3667 3668 /* Initialize the hash buckets. */ 3669 for (i = 0; i < tcp_syn_cache_size; i++) 3670 TAILQ_INIT(&tcp_syn_cache[i].sch_bucket); 3671 } 3672 3673 void 3674 syn_cache_insert(struct syn_cache *sc, struct tcpcb *tp) 3675 { 3676 struct syn_cache_head *scp; 3677 struct syn_cache *sc2; 3678 int s; 3679 3680 /* 3681 * If there are no entries in the hash table, reinitialize 3682 * the hash secrets. 3683 */ 3684 if (syn_cache_count == 0) { 3685 syn_hash1 = cprng_fast32(); 3686 syn_hash2 = cprng_fast32(); 3687 } 3688 3689 SYN_HASHALL(sc->sc_hash, &sc->sc_src.sa, &sc->sc_dst.sa); 3690 sc->sc_bucketidx = sc->sc_hash % tcp_syn_cache_size; 3691 scp = &tcp_syn_cache[sc->sc_bucketidx]; 3692 3693 /* 3694 * Make sure that we don't overflow the per-bucket 3695 * limit or the total cache size limit. 3696 */ 3697 s = splsoftnet(); 3698 if (scp->sch_length >= tcp_syn_bucket_limit) { 3699 TCP_STATINC(TCP_STAT_SC_BUCKETOVERFLOW); 3700 /* 3701 * The bucket is full. Toss the oldest element in the 3702 * bucket. This will be the first entry in the bucket. 3703 */ 3704 sc2 = TAILQ_FIRST(&scp->sch_bucket); 3705 #ifdef DIAGNOSTIC 3706 /* 3707 * This should never happen; we should always find an 3708 * entry in our bucket. 3709 */ 3710 if (sc2 == NULL) 3711 panic("syn_cache_insert: bucketoverflow: impossible"); 3712 #endif 3713 syn_cache_rm(sc2); 3714 syn_cache_put(sc2); /* calls pool_put but see spl above */ 3715 } else if (syn_cache_count >= tcp_syn_cache_limit) { 3716 struct syn_cache_head *scp2, *sce; 3717 3718 TCP_STATINC(TCP_STAT_SC_OVERFLOWED); 3719 /* 3720 * The cache is full. Toss the oldest entry in the 3721 * first non-empty bucket we can find. 3722 * 3723 * XXX We would really like to toss the oldest 3724 * entry in the cache, but we hope that this 3725 * condition doesn't happen very often. 3726 */ 3727 scp2 = scp; 3728 if (TAILQ_EMPTY(&scp2->sch_bucket)) { 3729 sce = &tcp_syn_cache[tcp_syn_cache_size]; 3730 for (++scp2; scp2 != scp; scp2++) { 3731 if (scp2 >= sce) 3732 scp2 = &tcp_syn_cache[0]; 3733 if (! TAILQ_EMPTY(&scp2->sch_bucket)) 3734 break; 3735 } 3736 #ifdef DIAGNOSTIC 3737 /* 3738 * This should never happen; we should always find a 3739 * non-empty bucket. 3740 */ 3741 if (scp2 == scp) 3742 panic("syn_cache_insert: cacheoverflow: " 3743 "impossible"); 3744 #endif 3745 } 3746 sc2 = TAILQ_FIRST(&scp2->sch_bucket); 3747 syn_cache_rm(sc2); 3748 syn_cache_put(sc2); /* calls pool_put but see spl above */ 3749 } 3750 3751 /* 3752 * Initialize the entry's timer. 3753 */ 3754 sc->sc_rxttot = 0; 3755 sc->sc_rxtshift = 0; 3756 SYN_CACHE_TIMER_ARM(sc); 3757 3758 /* Link it from tcpcb entry */ 3759 LIST_INSERT_HEAD(&tp->t_sc, sc, sc_tpq); 3760 3761 /* Put it into the bucket. */ 3762 TAILQ_INSERT_TAIL(&scp->sch_bucket, sc, sc_bucketq); 3763 scp->sch_length++; 3764 syn_cache_count++; 3765 3766 TCP_STATINC(TCP_STAT_SC_ADDED); 3767 splx(s); 3768 } 3769 3770 /* 3771 * Walk the timer queues, looking for SYN,ACKs that need to be retransmitted. 3772 * If we have retransmitted an entry the maximum number of times, expire 3773 * that entry. 3774 */ 3775 void 3776 syn_cache_timer(void *arg) 3777 { 3778 struct syn_cache *sc = arg; 3779 3780 mutex_enter(softnet_lock); 3781 KERNEL_LOCK(1, NULL); 3782 callout_ack(&sc->sc_timer); 3783 3784 if (__predict_false(sc->sc_flags & SCF_DEAD)) { 3785 TCP_STATINC(TCP_STAT_SC_DELAYED_FREE); 3786 callout_destroy(&sc->sc_timer); 3787 pool_put(&syn_cache_pool, sc); 3788 KERNEL_UNLOCK_ONE(NULL); 3789 mutex_exit(softnet_lock); 3790 return; 3791 } 3792 3793 if (__predict_false(sc->sc_rxtshift == TCP_MAXRXTSHIFT)) { 3794 /* Drop it -- too many retransmissions. */ 3795 goto dropit; 3796 } 3797 3798 /* 3799 * Compute the total amount of time this entry has 3800 * been on a queue. If this entry has been on longer 3801 * than the keep alive timer would allow, expire it. 3802 */ 3803 sc->sc_rxttot += sc->sc_rxtcur; 3804 if (sc->sc_rxttot >= tcp_keepinit) 3805 goto dropit; 3806 3807 TCP_STATINC(TCP_STAT_SC_RETRANSMITTED); 3808 (void) syn_cache_respond(sc, NULL); 3809 3810 /* Advance the timer back-off. */ 3811 sc->sc_rxtshift++; 3812 SYN_CACHE_TIMER_ARM(sc); 3813 3814 KERNEL_UNLOCK_ONE(NULL); 3815 mutex_exit(softnet_lock); 3816 return; 3817 3818 dropit: 3819 TCP_STATINC(TCP_STAT_SC_TIMED_OUT); 3820 syn_cache_rm(sc); 3821 if (sc->sc_ipopts) 3822 (void) m_free(sc->sc_ipopts); 3823 rtcache_free(&sc->sc_route); 3824 callout_destroy(&sc->sc_timer); 3825 pool_put(&syn_cache_pool, sc); 3826 KERNEL_UNLOCK_ONE(NULL); 3827 mutex_exit(softnet_lock); 3828 } 3829 3830 /* 3831 * Remove syn cache created by the specified tcb entry, 3832 * because this does not make sense to keep them 3833 * (if there's no tcb entry, syn cache entry will never be used) 3834 */ 3835 void 3836 syn_cache_cleanup(struct tcpcb *tp) 3837 { 3838 struct syn_cache *sc, *nsc; 3839 int s; 3840 3841 s = splsoftnet(); 3842 3843 for (sc = LIST_FIRST(&tp->t_sc); sc != NULL; sc = nsc) { 3844 nsc = LIST_NEXT(sc, sc_tpq); 3845 3846 #ifdef DIAGNOSTIC 3847 if (sc->sc_tp != tp) 3848 panic("invalid sc_tp in syn_cache_cleanup"); 3849 #endif 3850 syn_cache_rm(sc); 3851 syn_cache_put(sc); /* calls pool_put but see spl above */ 3852 } 3853 /* just for safety */ 3854 LIST_INIT(&tp->t_sc); 3855 3856 splx(s); 3857 } 3858 3859 /* 3860 * Find an entry in the syn cache. 3861 */ 3862 struct syn_cache * 3863 syn_cache_lookup(const struct sockaddr *src, const struct sockaddr *dst, 3864 struct syn_cache_head **headp) 3865 { 3866 struct syn_cache *sc; 3867 struct syn_cache_head *scp; 3868 u_int32_t hash; 3869 int s; 3870 3871 SYN_HASHALL(hash, src, dst); 3872 3873 scp = &tcp_syn_cache[hash % tcp_syn_cache_size]; 3874 *headp = scp; 3875 s = splsoftnet(); 3876 for (sc = TAILQ_FIRST(&scp->sch_bucket); sc != NULL; 3877 sc = TAILQ_NEXT(sc, sc_bucketq)) { 3878 if (sc->sc_hash != hash) 3879 continue; 3880 if (!memcmp(&sc->sc_src, src, src->sa_len) && 3881 !memcmp(&sc->sc_dst, dst, dst->sa_len)) { 3882 splx(s); 3883 return (sc); 3884 } 3885 } 3886 splx(s); 3887 return (NULL); 3888 } 3889 3890 /* 3891 * This function gets called when we receive an ACK for a 3892 * socket in the LISTEN state. We look up the connection 3893 * in the syn cache, and if its there, we pull it out of 3894 * the cache and turn it into a full-blown connection in 3895 * the SYN-RECEIVED state. 3896 * 3897 * The return values may not be immediately obvious, and their effects 3898 * can be subtle, so here they are: 3899 * 3900 * NULL SYN was not found in cache; caller should drop the 3901 * packet and send an RST. 3902 * 3903 * -1 We were unable to create the new connection, and are 3904 * aborting it. An ACK,RST is being sent to the peer 3905 * (unless we got screwey sequence numbners; see below), 3906 * because the 3-way handshake has been completed. Caller 3907 * should not free the mbuf, since we may be using it. If 3908 * we are not, we will free it. 3909 * 3910 * Otherwise, the return value is a pointer to the new socket 3911 * associated with the connection. 3912 */ 3913 struct socket * 3914 syn_cache_get(struct sockaddr *src, struct sockaddr *dst, 3915 struct tcphdr *th, unsigned int hlen, unsigned int tlen, 3916 struct socket *so, struct mbuf *m) 3917 { 3918 struct syn_cache *sc; 3919 struct syn_cache_head *scp; 3920 struct inpcb *inp = NULL; 3921 #ifdef INET6 3922 struct in6pcb *in6p = NULL; 3923 #endif 3924 struct tcpcb *tp = 0; 3925 struct mbuf *am; 3926 int s; 3927 struct socket *oso; 3928 3929 s = splsoftnet(); 3930 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 3931 splx(s); 3932 return (NULL); 3933 } 3934 3935 /* 3936 * Verify the sequence and ack numbers. Try getting the correct 3937 * response again. 3938 */ 3939 if ((th->th_ack != sc->sc_iss + 1) || 3940 SEQ_LEQ(th->th_seq, sc->sc_irs) || 3941 SEQ_GT(th->th_seq, sc->sc_irs + 1 + sc->sc_win)) { 3942 (void) syn_cache_respond(sc, m); 3943 splx(s); 3944 return ((struct socket *)(-1)); 3945 } 3946 3947 /* Remove this cache entry */ 3948 syn_cache_rm(sc); 3949 splx(s); 3950 3951 /* 3952 * Ok, create the full blown connection, and set things up 3953 * as they would have been set up if we had created the 3954 * connection when the SYN arrived. If we can't create 3955 * the connection, abort it. 3956 */ 3957 /* 3958 * inp still has the OLD in_pcb stuff, set the 3959 * v6-related flags on the new guy, too. This is 3960 * done particularly for the case where an AF_INET6 3961 * socket is bound only to a port, and a v4 connection 3962 * comes in on that port. 3963 * we also copy the flowinfo from the original pcb 3964 * to the new one. 3965 */ 3966 oso = so; 3967 so = sonewconn(so, true); 3968 if (so == NULL) 3969 goto resetandabort; 3970 3971 switch (so->so_proto->pr_domain->dom_family) { 3972 #ifdef INET 3973 case AF_INET: 3974 inp = sotoinpcb(so); 3975 break; 3976 #endif 3977 #ifdef INET6 3978 case AF_INET6: 3979 in6p = sotoin6pcb(so); 3980 break; 3981 #endif 3982 } 3983 switch (src->sa_family) { 3984 #ifdef INET 3985 case AF_INET: 3986 if (inp) { 3987 inp->inp_laddr = ((struct sockaddr_in *)dst)->sin_addr; 3988 inp->inp_lport = ((struct sockaddr_in *)dst)->sin_port; 3989 inp->inp_options = ip_srcroute(); 3990 in_pcbstate(inp, INP_BOUND); 3991 if (inp->inp_options == NULL) { 3992 inp->inp_options = sc->sc_ipopts; 3993 sc->sc_ipopts = NULL; 3994 } 3995 } 3996 #ifdef INET6 3997 else if (in6p) { 3998 /* IPv4 packet to AF_INET6 socket */ 3999 memset(&in6p->in6p_laddr, 0, sizeof(in6p->in6p_laddr)); 4000 in6p->in6p_laddr.s6_addr16[5] = htons(0xffff); 4001 bcopy(&((struct sockaddr_in *)dst)->sin_addr, 4002 &in6p->in6p_laddr.s6_addr32[3], 4003 sizeof(((struct sockaddr_in *)dst)->sin_addr)); 4004 in6p->in6p_lport = ((struct sockaddr_in *)dst)->sin_port; 4005 in6totcpcb(in6p)->t_family = AF_INET; 4006 if (sotoin6pcb(oso)->in6p_flags & IN6P_IPV6_V6ONLY) 4007 in6p->in6p_flags |= IN6P_IPV6_V6ONLY; 4008 else 4009 in6p->in6p_flags &= ~IN6P_IPV6_V6ONLY; 4010 in6_pcbstate(in6p, IN6P_BOUND); 4011 } 4012 #endif 4013 break; 4014 #endif 4015 #ifdef INET6 4016 case AF_INET6: 4017 if (in6p) { 4018 in6p->in6p_laddr = ((struct sockaddr_in6 *)dst)->sin6_addr; 4019 in6p->in6p_lport = ((struct sockaddr_in6 *)dst)->sin6_port; 4020 in6_pcbstate(in6p, IN6P_BOUND); 4021 } 4022 break; 4023 #endif 4024 } 4025 #ifdef INET6 4026 if (in6p && in6totcpcb(in6p)->t_family == AF_INET6 && sotoinpcb(oso)) { 4027 struct in6pcb *oin6p = sotoin6pcb(oso); 4028 /* inherit socket options from the listening socket */ 4029 in6p->in6p_flags |= (oin6p->in6p_flags & IN6P_CONTROLOPTS); 4030 if (in6p->in6p_flags & IN6P_CONTROLOPTS) { 4031 m_freem(in6p->in6p_options); 4032 in6p->in6p_options = 0; 4033 } 4034 ip6_savecontrol(in6p, &in6p->in6p_options, 4035 mtod(m, struct ip6_hdr *), m); 4036 } 4037 #endif 4038 4039 #if defined(IPSEC) 4040 if (ipsec_used) { 4041 /* 4042 * we make a copy of policy, instead of sharing the policy, for 4043 * better behavior in terms of SA lookup and dead SA removal. 4044 */ 4045 if (inp) { 4046 /* copy old policy into new socket's */ 4047 if (ipsec_copy_pcbpolicy(sotoinpcb(oso)->inp_sp, 4048 inp->inp_sp)) 4049 printf("tcp_input: could not copy policy\n"); 4050 } 4051 #ifdef INET6 4052 else if (in6p) { 4053 /* copy old policy into new socket's */ 4054 if (ipsec_copy_pcbpolicy(sotoin6pcb(oso)->in6p_sp, 4055 in6p->in6p_sp)) 4056 printf("tcp_input: could not copy policy\n"); 4057 } 4058 #endif 4059 } 4060 #endif 4061 4062 /* 4063 * Give the new socket our cached route reference. 4064 */ 4065 if (inp) { 4066 rtcache_copy(&inp->inp_route, &sc->sc_route); 4067 rtcache_free(&sc->sc_route); 4068 } 4069 #ifdef INET6 4070 else { 4071 rtcache_copy(&in6p->in6p_route, &sc->sc_route); 4072 rtcache_free(&sc->sc_route); 4073 } 4074 #endif 4075 4076 am = m_get(M_DONTWAIT, MT_SONAME); /* XXX */ 4077 if (am == NULL) 4078 goto resetandabort; 4079 MCLAIM(am, &tcp_mowner); 4080 am->m_len = src->sa_len; 4081 bcopy(src, mtod(am, void *), src->sa_len); 4082 if (inp) { 4083 if (in_pcbconnect(inp, am, &lwp0)) { 4084 (void) m_free(am); 4085 goto resetandabort; 4086 } 4087 } 4088 #ifdef INET6 4089 else if (in6p) { 4090 if (src->sa_family == AF_INET) { 4091 /* IPv4 packet to AF_INET6 socket */ 4092 struct sockaddr_in6 *sin6; 4093 sin6 = mtod(am, struct sockaddr_in6 *); 4094 am->m_len = sizeof(*sin6); 4095 memset(sin6, 0, sizeof(*sin6)); 4096 sin6->sin6_family = AF_INET6; 4097 sin6->sin6_len = sizeof(*sin6); 4098 sin6->sin6_port = ((struct sockaddr_in *)src)->sin_port; 4099 sin6->sin6_addr.s6_addr16[5] = htons(0xffff); 4100 bcopy(&((struct sockaddr_in *)src)->sin_addr, 4101 &sin6->sin6_addr.s6_addr32[3], 4102 sizeof(sin6->sin6_addr.s6_addr32[3])); 4103 } 4104 if (in6_pcbconnect(in6p, am, NULL)) { 4105 (void) m_free(am); 4106 goto resetandabort; 4107 } 4108 } 4109 #endif 4110 else { 4111 (void) m_free(am); 4112 goto resetandabort; 4113 } 4114 (void) m_free(am); 4115 4116 if (inp) 4117 tp = intotcpcb(inp); 4118 #ifdef INET6 4119 else if (in6p) 4120 tp = in6totcpcb(in6p); 4121 #endif 4122 else 4123 tp = NULL; 4124 tp->t_flags = sototcpcb(oso)->t_flags & TF_NODELAY; 4125 if (sc->sc_request_r_scale != 15) { 4126 tp->requested_s_scale = sc->sc_requested_s_scale; 4127 tp->request_r_scale = sc->sc_request_r_scale; 4128 tp->snd_scale = sc->sc_requested_s_scale; 4129 tp->rcv_scale = sc->sc_request_r_scale; 4130 tp->t_flags |= TF_REQ_SCALE|TF_RCVD_SCALE; 4131 } 4132 if (sc->sc_flags & SCF_TIMESTAMP) 4133 tp->t_flags |= TF_REQ_TSTMP|TF_RCVD_TSTMP; 4134 tp->ts_timebase = sc->sc_timebase; 4135 4136 tp->t_template = tcp_template(tp); 4137 if (tp->t_template == 0) { 4138 tp = tcp_drop(tp, ENOBUFS); /* destroys socket */ 4139 so = NULL; 4140 m_freem(m); 4141 goto abort; 4142 } 4143 4144 tp->iss = sc->sc_iss; 4145 tp->irs = sc->sc_irs; 4146 tcp_sendseqinit(tp); 4147 tcp_rcvseqinit(tp); 4148 tp->t_state = TCPS_SYN_RECEIVED; 4149 TCP_TIMER_ARM(tp, TCPT_KEEP, tp->t_keepinit); 4150 TCP_STATINC(TCP_STAT_ACCEPTS); 4151 4152 if ((sc->sc_flags & SCF_SACK_PERMIT) && tcp_do_sack) 4153 tp->t_flags |= TF_WILL_SACK; 4154 4155 if ((sc->sc_flags & SCF_ECN_PERMIT) && tcp_do_ecn) 4156 tp->t_flags |= TF_ECN_PERMIT; 4157 4158 #ifdef TCP_SIGNATURE 4159 if (sc->sc_flags & SCF_SIGNATURE) 4160 tp->t_flags |= TF_SIGNATURE; 4161 #endif 4162 4163 /* Initialize tp->t_ourmss before we deal with the peer's! */ 4164 tp->t_ourmss = sc->sc_ourmaxseg; 4165 tcp_mss_from_peer(tp, sc->sc_peermaxseg); 4166 4167 /* 4168 * Initialize the initial congestion window. If we 4169 * had to retransmit the SYN,ACK, we must initialize cwnd 4170 * to 1 segment (i.e. the Loss Window). 4171 */ 4172 if (sc->sc_rxtshift) 4173 tp->snd_cwnd = tp->t_peermss; 4174 else { 4175 int ss = tcp_init_win; 4176 #ifdef INET 4177 if (inp != NULL && in_localaddr(inp->inp_faddr)) 4178 ss = tcp_init_win_local; 4179 #endif 4180 #ifdef INET6 4181 if (in6p != NULL && in6_localaddr(&in6p->in6p_faddr)) 4182 ss = tcp_init_win_local; 4183 #endif 4184 tp->snd_cwnd = TCP_INITIAL_WINDOW(ss, tp->t_peermss); 4185 } 4186 4187 tcp_rmx_rtt(tp); 4188 tp->snd_wl1 = sc->sc_irs; 4189 tp->rcv_up = sc->sc_irs + 1; 4190 4191 /* 4192 * This is what whould have happened in tcp_output() when 4193 * the SYN,ACK was sent. 4194 */ 4195 tp->snd_up = tp->snd_una; 4196 tp->snd_max = tp->snd_nxt = tp->iss+1; 4197 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 4198 if (sc->sc_win > 0 && SEQ_GT(tp->rcv_nxt + sc->sc_win, tp->rcv_adv)) 4199 tp->rcv_adv = tp->rcv_nxt + sc->sc_win; 4200 tp->last_ack_sent = tp->rcv_nxt; 4201 tp->t_partialacks = -1; 4202 tp->t_dupacks = 0; 4203 4204 TCP_STATINC(TCP_STAT_SC_COMPLETED); 4205 s = splsoftnet(); 4206 syn_cache_put(sc); 4207 splx(s); 4208 return (so); 4209 4210 resetandabort: 4211 (void)tcp_respond(NULL, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 4212 abort: 4213 if (so != NULL) { 4214 (void) soqremque(so, 1); 4215 (void) soabort(so); 4216 mutex_enter(softnet_lock); 4217 } 4218 s = splsoftnet(); 4219 syn_cache_put(sc); 4220 splx(s); 4221 TCP_STATINC(TCP_STAT_SC_ABORTED); 4222 return ((struct socket *)(-1)); 4223 } 4224 4225 /* 4226 * This function is called when we get a RST for a 4227 * non-existent connection, so that we can see if the 4228 * connection is in the syn cache. If it is, zap it. 4229 */ 4230 4231 void 4232 syn_cache_reset(struct sockaddr *src, struct sockaddr *dst, struct tcphdr *th) 4233 { 4234 struct syn_cache *sc; 4235 struct syn_cache_head *scp; 4236 int s = splsoftnet(); 4237 4238 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 4239 splx(s); 4240 return; 4241 } 4242 if (SEQ_LT(th->th_seq, sc->sc_irs) || 4243 SEQ_GT(th->th_seq, sc->sc_irs+1)) { 4244 splx(s); 4245 return; 4246 } 4247 syn_cache_rm(sc); 4248 TCP_STATINC(TCP_STAT_SC_RESET); 4249 syn_cache_put(sc); /* calls pool_put but see spl above */ 4250 splx(s); 4251 } 4252 4253 void 4254 syn_cache_unreach(const struct sockaddr *src, const struct sockaddr *dst, 4255 struct tcphdr *th) 4256 { 4257 struct syn_cache *sc; 4258 struct syn_cache_head *scp; 4259 int s; 4260 4261 s = splsoftnet(); 4262 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 4263 splx(s); 4264 return; 4265 } 4266 /* If the sequence number != sc_iss, then it's a bogus ICMP msg */ 4267 if (ntohl (th->th_seq) != sc->sc_iss) { 4268 splx(s); 4269 return; 4270 } 4271 4272 /* 4273 * If we've retransmitted 3 times and this is our second error, 4274 * we remove the entry. Otherwise, we allow it to continue on. 4275 * This prevents us from incorrectly nuking an entry during a 4276 * spurious network outage. 4277 * 4278 * See tcp_notify(). 4279 */ 4280 if ((sc->sc_flags & SCF_UNREACH) == 0 || sc->sc_rxtshift < 3) { 4281 sc->sc_flags |= SCF_UNREACH; 4282 splx(s); 4283 return; 4284 } 4285 4286 syn_cache_rm(sc); 4287 TCP_STATINC(TCP_STAT_SC_UNREACH); 4288 syn_cache_put(sc); /* calls pool_put but see spl above */ 4289 splx(s); 4290 } 4291 4292 /* 4293 * Given a LISTEN socket and an inbound SYN request, add 4294 * this to the syn cache, and send back a segment: 4295 * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK> 4296 * to the source. 4297 * 4298 * IMPORTANT NOTE: We do _NOT_ ACK data that might accompany the SYN. 4299 * Doing so would require that we hold onto the data and deliver it 4300 * to the application. However, if we are the target of a SYN-flood 4301 * DoS attack, an attacker could send data which would eventually 4302 * consume all available buffer space if it were ACKed. By not ACKing 4303 * the data, we avoid this DoS scenario. 4304 */ 4305 4306 int 4307 syn_cache_add(struct sockaddr *src, struct sockaddr *dst, struct tcphdr *th, 4308 unsigned int hlen, struct socket *so, struct mbuf *m, u_char *optp, 4309 int optlen, struct tcp_opt_info *oi) 4310 { 4311 struct tcpcb tb, *tp; 4312 long win; 4313 struct syn_cache *sc; 4314 struct syn_cache_head *scp; 4315 struct mbuf *ipopts; 4316 struct tcp_opt_info opti; 4317 int s; 4318 4319 tp = sototcpcb(so); 4320 4321 memset(&opti, 0, sizeof(opti)); 4322 4323 /* 4324 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN 4325 * 4326 * Note this check is performed in tcp_input() very early on. 4327 */ 4328 4329 /* 4330 * Initialize some local state. 4331 */ 4332 win = sbspace(&so->so_rcv); 4333 if (win > TCP_MAXWIN) 4334 win = TCP_MAXWIN; 4335 4336 switch (src->sa_family) { 4337 #ifdef INET 4338 case AF_INET: 4339 /* 4340 * Remember the IP options, if any. 4341 */ 4342 ipopts = ip_srcroute(); 4343 break; 4344 #endif 4345 default: 4346 ipopts = NULL; 4347 } 4348 4349 #ifdef TCP_SIGNATURE 4350 if (optp || (tp->t_flags & TF_SIGNATURE)) 4351 #else 4352 if (optp) 4353 #endif 4354 { 4355 tb.t_flags = tcp_do_rfc1323 ? (TF_REQ_SCALE|TF_REQ_TSTMP) : 0; 4356 #ifdef TCP_SIGNATURE 4357 tb.t_flags |= (tp->t_flags & TF_SIGNATURE); 4358 #endif 4359 tb.t_state = TCPS_LISTEN; 4360 if (tcp_dooptions(&tb, optp, optlen, th, m, m->m_pkthdr.len - 4361 sizeof(struct tcphdr) - optlen - hlen, oi) < 0) 4362 return (0); 4363 } else 4364 tb.t_flags = 0; 4365 4366 /* 4367 * See if we already have an entry for this connection. 4368 * If we do, resend the SYN,ACK. We do not count this 4369 * as a retransmission (XXX though maybe we should). 4370 */ 4371 if ((sc = syn_cache_lookup(src, dst, &scp)) != NULL) { 4372 TCP_STATINC(TCP_STAT_SC_DUPESYN); 4373 if (ipopts) { 4374 /* 4375 * If we were remembering a previous source route, 4376 * forget it and use the new one we've been given. 4377 */ 4378 if (sc->sc_ipopts) 4379 (void) m_free(sc->sc_ipopts); 4380 sc->sc_ipopts = ipopts; 4381 } 4382 sc->sc_timestamp = tb.ts_recent; 4383 if (syn_cache_respond(sc, m) == 0) { 4384 uint64_t *tcps = TCP_STAT_GETREF(); 4385 tcps[TCP_STAT_SNDACKS]++; 4386 tcps[TCP_STAT_SNDTOTAL]++; 4387 TCP_STAT_PUTREF(); 4388 } 4389 return (1); 4390 } 4391 4392 s = splsoftnet(); 4393 sc = pool_get(&syn_cache_pool, PR_NOWAIT); 4394 splx(s); 4395 if (sc == NULL) { 4396 if (ipopts) 4397 (void) m_free(ipopts); 4398 return (0); 4399 } 4400 4401 /* 4402 * Fill in the cache, and put the necessary IP and TCP 4403 * options into the reply. 4404 */ 4405 memset(sc, 0, sizeof(struct syn_cache)); 4406 callout_init(&sc->sc_timer, CALLOUT_MPSAFE); 4407 bcopy(src, &sc->sc_src, src->sa_len); 4408 bcopy(dst, &sc->sc_dst, dst->sa_len); 4409 sc->sc_flags = 0; 4410 sc->sc_ipopts = ipopts; 4411 sc->sc_irs = th->th_seq; 4412 switch (src->sa_family) { 4413 #ifdef INET 4414 case AF_INET: 4415 { 4416 struct sockaddr_in *srcin = (void *) src; 4417 struct sockaddr_in *dstin = (void *) dst; 4418 4419 sc->sc_iss = tcp_new_iss1(&dstin->sin_addr, 4420 &srcin->sin_addr, dstin->sin_port, 4421 srcin->sin_port, sizeof(dstin->sin_addr), 0); 4422 break; 4423 } 4424 #endif /* INET */ 4425 #ifdef INET6 4426 case AF_INET6: 4427 { 4428 struct sockaddr_in6 *srcin6 = (void *) src; 4429 struct sockaddr_in6 *dstin6 = (void *) dst; 4430 4431 sc->sc_iss = tcp_new_iss1(&dstin6->sin6_addr, 4432 &srcin6->sin6_addr, dstin6->sin6_port, 4433 srcin6->sin6_port, sizeof(dstin6->sin6_addr), 0); 4434 break; 4435 } 4436 #endif /* INET6 */ 4437 } 4438 sc->sc_peermaxseg = oi->maxseg; 4439 sc->sc_ourmaxseg = tcp_mss_to_advertise(m->m_flags & M_PKTHDR ? 4440 m->m_pkthdr.rcvif : NULL, 4441 sc->sc_src.sa.sa_family); 4442 sc->sc_win = win; 4443 sc->sc_timebase = tcp_now - 1; /* see tcp_newtcpcb() */ 4444 sc->sc_timestamp = tb.ts_recent; 4445 if ((tb.t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP)) == 4446 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) 4447 sc->sc_flags |= SCF_TIMESTAMP; 4448 if ((tb.t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 4449 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 4450 sc->sc_requested_s_scale = tb.requested_s_scale; 4451 sc->sc_request_r_scale = 0; 4452 /* 4453 * Pick the smallest possible scaling factor that 4454 * will still allow us to scale up to sb_max. 4455 * 4456 * We do this because there are broken firewalls that 4457 * will corrupt the window scale option, leading to 4458 * the other endpoint believing that our advertised 4459 * window is unscaled. At scale factors larger than 4460 * 5 the unscaled window will drop below 1500 bytes, 4461 * leading to serious problems when traversing these 4462 * broken firewalls. 4463 * 4464 * With the default sbmax of 256K, a scale factor 4465 * of 3 will be chosen by this algorithm. Those who 4466 * choose a larger sbmax should watch out 4467 * for the compatiblity problems mentioned above. 4468 * 4469 * RFC1323: The Window field in a SYN (i.e., a <SYN> 4470 * or <SYN,ACK>) segment itself is never scaled. 4471 */ 4472 while (sc->sc_request_r_scale < TCP_MAX_WINSHIFT && 4473 (TCP_MAXWIN << sc->sc_request_r_scale) < sb_max) 4474 sc->sc_request_r_scale++; 4475 } else { 4476 sc->sc_requested_s_scale = 15; 4477 sc->sc_request_r_scale = 15; 4478 } 4479 if ((tb.t_flags & TF_SACK_PERMIT) && tcp_do_sack) 4480 sc->sc_flags |= SCF_SACK_PERMIT; 4481 4482 /* 4483 * ECN setup packet recieved. 4484 */ 4485 if ((th->th_flags & (TH_ECE|TH_CWR)) && tcp_do_ecn) 4486 sc->sc_flags |= SCF_ECN_PERMIT; 4487 4488 #ifdef TCP_SIGNATURE 4489 if (tb.t_flags & TF_SIGNATURE) 4490 sc->sc_flags |= SCF_SIGNATURE; 4491 #endif 4492 sc->sc_tp = tp; 4493 if (syn_cache_respond(sc, m) == 0) { 4494 uint64_t *tcps = TCP_STAT_GETREF(); 4495 tcps[TCP_STAT_SNDACKS]++; 4496 tcps[TCP_STAT_SNDTOTAL]++; 4497 TCP_STAT_PUTREF(); 4498 syn_cache_insert(sc, tp); 4499 } else { 4500 s = splsoftnet(); 4501 /* 4502 * syn_cache_put() will try to schedule the timer, so 4503 * we need to initialize it 4504 */ 4505 SYN_CACHE_TIMER_ARM(sc); 4506 syn_cache_put(sc); 4507 splx(s); 4508 TCP_STATINC(TCP_STAT_SC_DROPPED); 4509 } 4510 return (1); 4511 } 4512 4513 /* 4514 * syn_cache_respond: (re)send SYN+ACK. 4515 * 4516 * returns 0 on success. otherwise returns an errno, typically ENOBUFS. 4517 */ 4518 4519 int 4520 syn_cache_respond(struct syn_cache *sc, struct mbuf *m) 4521 { 4522 #ifdef INET6 4523 struct rtentry *rt; 4524 #endif 4525 struct route *ro; 4526 u_int8_t *optp; 4527 int optlen, error; 4528 u_int16_t tlen; 4529 struct ip *ip = NULL; 4530 #ifdef INET6 4531 struct ip6_hdr *ip6 = NULL; 4532 #endif 4533 struct tcpcb *tp = NULL; 4534 struct tcphdr *th; 4535 u_int hlen; 4536 struct socket *so; 4537 4538 ro = &sc->sc_route; 4539 switch (sc->sc_src.sa.sa_family) { 4540 case AF_INET: 4541 hlen = sizeof(struct ip); 4542 break; 4543 #ifdef INET6 4544 case AF_INET6: 4545 hlen = sizeof(struct ip6_hdr); 4546 break; 4547 #endif 4548 default: 4549 if (m) 4550 m_freem(m); 4551 return (EAFNOSUPPORT); 4552 } 4553 4554 /* Compute the size of the TCP options. */ 4555 optlen = 4 + (sc->sc_request_r_scale != 15 ? 4 : 0) + 4556 ((sc->sc_flags & SCF_SACK_PERMIT) ? (TCPOLEN_SACK_PERMITTED + 2) : 0) + 4557 #ifdef TCP_SIGNATURE 4558 ((sc->sc_flags & SCF_SIGNATURE) ? (TCPOLEN_SIGNATURE + 2) : 0) + 4559 #endif 4560 ((sc->sc_flags & SCF_TIMESTAMP) ? TCPOLEN_TSTAMP_APPA : 0); 4561 4562 tlen = hlen + sizeof(struct tcphdr) + optlen; 4563 4564 /* 4565 * Create the IP+TCP header from scratch. 4566 */ 4567 if (m) 4568 m_freem(m); 4569 #ifdef DIAGNOSTIC 4570 if (max_linkhdr + tlen > MCLBYTES) 4571 return (ENOBUFS); 4572 #endif 4573 MGETHDR(m, M_DONTWAIT, MT_DATA); 4574 if (m && (max_linkhdr + tlen) > MHLEN) { 4575 MCLGET(m, M_DONTWAIT); 4576 if ((m->m_flags & M_EXT) == 0) { 4577 m_freem(m); 4578 m = NULL; 4579 } 4580 } 4581 if (m == NULL) 4582 return (ENOBUFS); 4583 MCLAIM(m, &tcp_tx_mowner); 4584 4585 /* Fixup the mbuf. */ 4586 m->m_data += max_linkhdr; 4587 m->m_len = m->m_pkthdr.len = tlen; 4588 if (sc->sc_tp) { 4589 tp = sc->sc_tp; 4590 if (tp->t_inpcb) 4591 so = tp->t_inpcb->inp_socket; 4592 #ifdef INET6 4593 else if (tp->t_in6pcb) 4594 so = tp->t_in6pcb->in6p_socket; 4595 #endif 4596 else 4597 so = NULL; 4598 } else 4599 so = NULL; 4600 m->m_pkthdr.rcvif = NULL; 4601 memset(mtod(m, u_char *), 0, tlen); 4602 4603 switch (sc->sc_src.sa.sa_family) { 4604 case AF_INET: 4605 ip = mtod(m, struct ip *); 4606 ip->ip_v = 4; 4607 ip->ip_dst = sc->sc_src.sin.sin_addr; 4608 ip->ip_src = sc->sc_dst.sin.sin_addr; 4609 ip->ip_p = IPPROTO_TCP; 4610 th = (struct tcphdr *)(ip + 1); 4611 th->th_dport = sc->sc_src.sin.sin_port; 4612 th->th_sport = sc->sc_dst.sin.sin_port; 4613 break; 4614 #ifdef INET6 4615 case AF_INET6: 4616 ip6 = mtod(m, struct ip6_hdr *); 4617 ip6->ip6_vfc = IPV6_VERSION; 4618 ip6->ip6_dst = sc->sc_src.sin6.sin6_addr; 4619 ip6->ip6_src = sc->sc_dst.sin6.sin6_addr; 4620 ip6->ip6_nxt = IPPROTO_TCP; 4621 /* ip6_plen will be updated in ip6_output() */ 4622 th = (struct tcphdr *)(ip6 + 1); 4623 th->th_dport = sc->sc_src.sin6.sin6_port; 4624 th->th_sport = sc->sc_dst.sin6.sin6_port; 4625 break; 4626 #endif 4627 default: 4628 th = NULL; 4629 } 4630 4631 th->th_seq = htonl(sc->sc_iss); 4632 th->th_ack = htonl(sc->sc_irs + 1); 4633 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 4634 th->th_flags = TH_SYN|TH_ACK; 4635 th->th_win = htons(sc->sc_win); 4636 /* th_sum already 0 */ 4637 /* th_urp already 0 */ 4638 4639 /* Tack on the TCP options. */ 4640 optp = (u_int8_t *)(th + 1); 4641 *optp++ = TCPOPT_MAXSEG; 4642 *optp++ = 4; 4643 *optp++ = (sc->sc_ourmaxseg >> 8) & 0xff; 4644 *optp++ = sc->sc_ourmaxseg & 0xff; 4645 4646 if (sc->sc_request_r_scale != 15) { 4647 *((u_int32_t *)optp) = htonl(TCPOPT_NOP << 24 | 4648 TCPOPT_WINDOW << 16 | TCPOLEN_WINDOW << 8 | 4649 sc->sc_request_r_scale); 4650 optp += 4; 4651 } 4652 4653 if (sc->sc_flags & SCF_TIMESTAMP) { 4654 u_int32_t *lp = (u_int32_t *)(optp); 4655 /* Form timestamp option as shown in appendix A of RFC 1323. */ 4656 *lp++ = htonl(TCPOPT_TSTAMP_HDR); 4657 *lp++ = htonl(SYN_CACHE_TIMESTAMP(sc)); 4658 *lp = htonl(sc->sc_timestamp); 4659 optp += TCPOLEN_TSTAMP_APPA; 4660 } 4661 4662 if (sc->sc_flags & SCF_SACK_PERMIT) { 4663 u_int8_t *p = optp; 4664 4665 /* Let the peer know that we will SACK. */ 4666 p[0] = TCPOPT_SACK_PERMITTED; 4667 p[1] = 2; 4668 p[2] = TCPOPT_NOP; 4669 p[3] = TCPOPT_NOP; 4670 optp += 4; 4671 } 4672 4673 /* 4674 * Send ECN SYN-ACK setup packet. 4675 * Routes can be asymetric, so, even if we receive a packet 4676 * with ECE and CWR set, we must not assume no one will block 4677 * the ECE packet we are about to send. 4678 */ 4679 if ((sc->sc_flags & SCF_ECN_PERMIT) && tp && 4680 SEQ_GEQ(tp->snd_nxt, tp->snd_max)) { 4681 th->th_flags |= TH_ECE; 4682 TCP_STATINC(TCP_STAT_ECN_SHS); 4683 4684 /* 4685 * draft-ietf-tcpm-ecnsyn-00.txt 4686 * 4687 * "[...] a TCP node MAY respond to an ECN-setup 4688 * SYN packet by setting ECT in the responding 4689 * ECN-setup SYN/ACK packet, indicating to routers 4690 * that the SYN/ACK packet is ECN-Capable. 4691 * This allows a congested router along the path 4692 * to mark the packet instead of dropping the 4693 * packet as an indication of congestion." 4694 * 4695 * "[...] There can be a great benefit in setting 4696 * an ECN-capable codepoint in SYN/ACK packets [...] 4697 * Congestion is most likely to occur in 4698 * the server-to-client direction. As a result, 4699 * setting an ECN-capable codepoint in SYN/ACK 4700 * packets can reduce the occurence of three-second 4701 * retransmit timeouts resulting from the drop 4702 * of SYN/ACK packets." 4703 * 4704 * Page 4 and 6, January 2006. 4705 */ 4706 4707 switch (sc->sc_src.sa.sa_family) { 4708 #ifdef INET 4709 case AF_INET: 4710 ip->ip_tos |= IPTOS_ECN_ECT0; 4711 break; 4712 #endif 4713 #ifdef INET6 4714 case AF_INET6: 4715 ip6->ip6_flow |= htonl(IPTOS_ECN_ECT0 << 20); 4716 break; 4717 #endif 4718 } 4719 TCP_STATINC(TCP_STAT_ECN_ECT); 4720 } 4721 4722 #ifdef TCP_SIGNATURE 4723 if (sc->sc_flags & SCF_SIGNATURE) { 4724 struct secasvar *sav; 4725 u_int8_t *sigp; 4726 4727 sav = tcp_signature_getsav(m, th); 4728 4729 if (sav == NULL) { 4730 if (m) 4731 m_freem(m); 4732 return (EPERM); 4733 } 4734 4735 *optp++ = TCPOPT_SIGNATURE; 4736 *optp++ = TCPOLEN_SIGNATURE; 4737 sigp = optp; 4738 memset(optp, 0, TCP_SIGLEN); 4739 optp += TCP_SIGLEN; 4740 *optp++ = TCPOPT_NOP; 4741 *optp++ = TCPOPT_EOL; 4742 4743 (void)tcp_signature(m, th, hlen, sav, sigp); 4744 4745 key_sa_recordxfer(sav, m); 4746 KEY_FREESAV(&sav); 4747 } 4748 #endif 4749 4750 /* Compute the packet's checksum. */ 4751 switch (sc->sc_src.sa.sa_family) { 4752 case AF_INET: 4753 ip->ip_len = htons(tlen - hlen); 4754 th->th_sum = 0; 4755 th->th_sum = in4_cksum(m, IPPROTO_TCP, hlen, tlen - hlen); 4756 break; 4757 #ifdef INET6 4758 case AF_INET6: 4759 ip6->ip6_plen = htons(tlen - hlen); 4760 th->th_sum = 0; 4761 th->th_sum = in6_cksum(m, IPPROTO_TCP, hlen, tlen - hlen); 4762 break; 4763 #endif 4764 } 4765 4766 /* 4767 * Fill in some straggling IP bits. Note the stack expects 4768 * ip_len to be in host order, for convenience. 4769 */ 4770 switch (sc->sc_src.sa.sa_family) { 4771 #ifdef INET 4772 case AF_INET: 4773 ip->ip_len = htons(tlen); 4774 ip->ip_ttl = ip_defttl; 4775 /* XXX tos? */ 4776 break; 4777 #endif 4778 #ifdef INET6 4779 case AF_INET6: 4780 ip6->ip6_vfc &= ~IPV6_VERSION_MASK; 4781 ip6->ip6_vfc |= IPV6_VERSION; 4782 ip6->ip6_plen = htons(tlen - hlen); 4783 /* ip6_hlim will be initialized afterwards */ 4784 /* XXX flowlabel? */ 4785 break; 4786 #endif 4787 } 4788 4789 /* XXX use IPsec policy on listening socket, on SYN ACK */ 4790 tp = sc->sc_tp; 4791 4792 switch (sc->sc_src.sa.sa_family) { 4793 #ifdef INET 4794 case AF_INET: 4795 error = ip_output(m, sc->sc_ipopts, ro, 4796 (ip_mtudisc ? IP_MTUDISC : 0), 4797 NULL, so); 4798 break; 4799 #endif 4800 #ifdef INET6 4801 case AF_INET6: 4802 ip6->ip6_hlim = in6_selecthlim(NULL, 4803 (rt = rtcache_validate(ro)) != NULL ? rt->rt_ifp 4804 : NULL); 4805 4806 error = ip6_output(m, NULL /*XXX*/, ro, 0, NULL, so, NULL); 4807 break; 4808 #endif 4809 default: 4810 error = EAFNOSUPPORT; 4811 break; 4812 } 4813 return (error); 4814 } 4815
Indexes created Tue Sep 23 01:09:51 GMT 2025