tcp_input.c revision 1.323
1 /* $NetBSD: tcp_input.c,v 1.323 2012/04/13 15:35:57 yamt 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 1.323 2012/04/13 15:35:57 yamt 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 FAST_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 /* FAST_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, dupseg; 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 dupseg = false; 1007 1008 if (todrop > 0) { 1009 if (tiflags & TH_SYN) { 1010 tiflags &= ~TH_SYN; 1011 ++th->th_seq; 1012 if (th->th_urp > 1) 1013 --th->th_urp; 1014 else { 1015 tiflags &= ~TH_URG; 1016 th->th_urp = 0; 1017 } 1018 --todrop; 1019 } 1020 if (todrop > tlen || 1021 (todrop == tlen && (tiflags & TH_FIN) == 0)) { 1022 /* 1023 * Any valid FIN or RST must be to the left of the 1024 * window. At this point the FIN or RST must be a 1025 * duplicate or out of sequence; drop it. 1026 */ 1027 if (tiflags & TH_RST) 1028 goto drop; 1029 tiflags &= ~(TH_FIN|TH_RST); 1030 /* 1031 * Send an ACK to resynchronize and drop any data. 1032 * But keep on processing for RST or ACK. 1033 */ 1034 t_flags |= TF_ACKNOW; 1035 todrop = tlen; 1036 dupseg = true; 1037 tcps = TCP_STAT_GETREF(); 1038 tcps[TCP_STAT_RCVDUPPACK] += 1; 1039 tcps[TCP_STAT_RCVDUPBYTE] += todrop; 1040 TCP_STAT_PUTREF(); 1041 } else if ((tiflags & TH_RST) 1042 && th->th_seq != vp->rcv_nxt) { 1043 /* 1044 * Test for reset before adjusting the sequence 1045 * number for overlapping data. 1046 */ 1047 goto dropafterack_ratelim; 1048 } else { 1049 tcps = TCP_STAT_GETREF(); 1050 tcps[TCP_STAT_RCVPARTDUPPACK] += 1; 1051 tcps[TCP_STAT_RCVPARTDUPBYTE] += todrop; 1052 TCP_STAT_PUTREF(); 1053 } 1054 1055 // tcp_new_dsack(tp, th->th_seq, todrop); 1056 // hdroptlen += todrop; /*drop from head afterwards*/ 1057 1058 th->th_seq += todrop; 1059 tlen -= todrop; 1060 1061 if (th->th_urp > todrop) 1062 th->th_urp -= todrop; 1063 else { 1064 tiflags &= ~TH_URG; 1065 th->th_urp = 0; 1066 } 1067 } 1068 1069 /* 1070 * If new data are received on a connection after the 1071 * user processes are gone, then RST the other end. 1072 */ 1073 if (tlen) { 1074 TCP_STATINC(TCP_STAT_RCVAFTERCLOSE); 1075 goto dropwithreset; 1076 } 1077 1078 /* 1079 * If segment ends after window, drop trailing data 1080 * (and PUSH and FIN); if nothing left, just ACK. 1081 */ 1082 todrop = (th->th_seq + tlen) - (vp->rcv_nxt+vp->rcv_wnd); 1083 1084 if (todrop > 0) { 1085 TCP_STATINC(TCP_STAT_RCVPACKAFTERWIN); 1086 if (todrop >= tlen) { 1087 /* 1088 * The segment actually starts after the window. 1089 * th->th_seq + tlen - vp->rcv_nxt - vp->rcv_wnd >= tlen 1090 * th->th_seq - vp->rcv_nxt - vp->rcv_wnd >= 0 1091 * th->th_seq >= vp->rcv_nxt + vp->rcv_wnd 1092 */ 1093 TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, tlen); 1094 /* 1095 * If a new connection request is received 1096 * while in TIME_WAIT, drop the old connection 1097 * and start over if the sequence numbers 1098 * are above the previous ones. 1099 */ 1100 if ((tiflags & TH_SYN) 1101 && SEQ_GT(th->th_seq, vp->rcv_nxt)) { 1102 /* We only support this in the !NOFDREF case, which 1103 * is to say: not here. 1104 */ 1105 goto dropwithreset;; 1106 } 1107 /* 1108 * If window is closed can only take segments at 1109 * window edge, and have to drop data and PUSH from 1110 * incoming segments. Continue processing, but 1111 * remember to ack. Otherwise, drop segment 1112 * and (if not RST) ack. 1113 */ 1114 if (vp->rcv_wnd == 0 && th->th_seq == vp->rcv_nxt) { 1115 t_flags |= TF_ACKNOW; 1116 TCP_STATINC(TCP_STAT_RCVWINPROBE); 1117 } else 1118 goto dropafterack; 1119 } else 1120 TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, todrop); 1121 m_adj(m, -todrop); 1122 tlen -= todrop; 1123 tiflags &= ~(TH_PUSH|TH_FIN); 1124 } 1125 1126 if (tiflags & TH_RST) { 1127 if (th->th_seq != vp->rcv_nxt) 1128 goto dropafterack_ratelim; 1129 1130 vtw_del(vp->ctl, vp->vtw); 1131 goto drop; 1132 } 1133 1134 /* 1135 * If the ACK bit is off we drop the segment and return. 1136 */ 1137 if ((tiflags & TH_ACK) == 0) { 1138 if (t_flags & TF_ACKNOW) 1139 goto dropafterack; 1140 else 1141 goto drop; 1142 } 1143 1144 /* 1145 * In TIME_WAIT state the only thing that should arrive 1146 * is a retransmission of the remote FIN. Acknowledge 1147 * it and restart the finack timer. 1148 */ 1149 vtw_restart(vp); 1150 goto dropafterack; 1151 1152 dropafterack: 1153 /* 1154 * Generate an ACK dropping incoming segment if it occupies 1155 * sequence space, where the ACK reflects our state. 1156 */ 1157 if (tiflags & TH_RST) 1158 goto drop; 1159 goto dropafterack2; 1160 1161 dropafterack_ratelim: 1162 /* 1163 * We may want to rate-limit ACKs against SYN/RST attack. 1164 */ 1165 if (ppsratecheck(&tcp_ackdrop_ppslim_last, &tcp_ackdrop_ppslim_count, 1166 tcp_ackdrop_ppslim) == 0) { 1167 /* XXX stat */ 1168 goto drop; 1169 } 1170 /* ...fall into dropafterack2... */ 1171 1172 dropafterack2: 1173 (void)tcp_respond(0, m, m, th, th->th_seq + tlen, th->th_ack, 1174 TH_ACK); 1175 return; 1176 1177 dropwithreset: 1178 /* 1179 * Generate a RST, dropping incoming segment. 1180 * Make ACK acceptable to originator of segment. 1181 */ 1182 if (tiflags & TH_RST) 1183 goto drop; 1184 1185 if (tiflags & TH_ACK) 1186 tcp_respond(0, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 1187 else { 1188 if (tiflags & TH_SYN) 1189 ++tlen; 1190 (void)tcp_respond(0, m, m, th, th->th_seq + tlen, (tcp_seq)0, 1191 TH_RST|TH_ACK); 1192 } 1193 return; 1194 drop: 1195 m_freem(m); 1196 } 1197 1198 /* 1199 * TCP input routine, follows pages 65-76 of RFC 793 very closely. 1200 */ 1201 void 1202 tcp_input(struct mbuf *m, ...) 1203 { 1204 struct tcphdr *th; 1205 struct ip *ip; 1206 struct inpcb *inp; 1207 #ifdef INET6 1208 struct ip6_hdr *ip6; 1209 struct in6pcb *in6p; 1210 #endif 1211 u_int8_t *optp = NULL; 1212 int optlen = 0; 1213 int len, tlen, toff, hdroptlen = 0; 1214 struct tcpcb *tp = 0; 1215 int tiflags; 1216 struct socket *so = NULL; 1217 int todrop, acked, ourfinisacked, needoutput = 0; 1218 bool dupseg; 1219 #ifdef TCP_DEBUG 1220 short ostate = 0; 1221 #endif 1222 u_long tiwin; 1223 struct tcp_opt_info opti; 1224 int off, iphlen; 1225 va_list ap; 1226 int af; /* af on the wire */ 1227 struct mbuf *tcp_saveti = NULL; 1228 uint32_t ts_rtt; 1229 uint8_t iptos; 1230 uint64_t *tcps; 1231 vestigial_inpcb_t vestige; 1232 1233 vestige.valid = 0; 1234 1235 MCLAIM(m, &tcp_rx_mowner); 1236 va_start(ap, m); 1237 toff = va_arg(ap, int); 1238 (void)va_arg(ap, int); /* ignore value, advance ap */ 1239 va_end(ap); 1240 1241 TCP_STATINC(TCP_STAT_RCVTOTAL); 1242 1243 memset(&opti, 0, sizeof(opti)); 1244 opti.ts_present = 0; 1245 opti.maxseg = 0; 1246 1247 /* 1248 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN. 1249 * 1250 * TCP is, by definition, unicast, so we reject all 1251 * multicast outright. 1252 * 1253 * Note, there are additional src/dst address checks in 1254 * the AF-specific code below. 1255 */ 1256 if (m->m_flags & (M_BCAST|M_MCAST)) { 1257 /* XXX stat */ 1258 goto drop; 1259 } 1260 #ifdef INET6 1261 if (m->m_flags & M_ANYCAST6) { 1262 /* XXX stat */ 1263 goto drop; 1264 } 1265 #endif 1266 1267 /* 1268 * Get IP and TCP header. 1269 * Note: IP leaves IP header in first mbuf. 1270 */ 1271 ip = mtod(m, struct ip *); 1272 switch (ip->ip_v) { 1273 #ifdef INET 1274 case 4: 1275 #ifdef INET6 1276 ip6 = NULL; 1277 #endif 1278 af = AF_INET; 1279 iphlen = sizeof(struct ip); 1280 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, 1281 sizeof(struct tcphdr)); 1282 if (th == NULL) { 1283 TCP_STATINC(TCP_STAT_RCVSHORT); 1284 return; 1285 } 1286 /* We do the checksum after PCB lookup... */ 1287 len = ntohs(ip->ip_len); 1288 tlen = len - toff; 1289 iptos = ip->ip_tos; 1290 break; 1291 #endif 1292 #ifdef INET6 1293 case 6: 1294 ip = NULL; 1295 iphlen = sizeof(struct ip6_hdr); 1296 af = AF_INET6; 1297 ip6 = mtod(m, struct ip6_hdr *); 1298 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, 1299 sizeof(struct tcphdr)); 1300 if (th == NULL) { 1301 TCP_STATINC(TCP_STAT_RCVSHORT); 1302 return; 1303 } 1304 1305 /* Be proactive about malicious use of IPv4 mapped address */ 1306 if (IN6_IS_ADDR_V4MAPPED(&ip6->ip6_src) || 1307 IN6_IS_ADDR_V4MAPPED(&ip6->ip6_dst)) { 1308 /* XXX stat */ 1309 goto drop; 1310 } 1311 1312 /* 1313 * Be proactive about unspecified IPv6 address in source. 1314 * As we use all-zero to indicate unbounded/unconnected pcb, 1315 * unspecified IPv6 address can be used to confuse us. 1316 * 1317 * Note that packets with unspecified IPv6 destination is 1318 * already dropped in ip6_input. 1319 */ 1320 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 1321 /* XXX stat */ 1322 goto drop; 1323 } 1324 1325 /* 1326 * Make sure destination address is not multicast. 1327 * Source address checked in ip6_input(). 1328 */ 1329 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) { 1330 /* XXX stat */ 1331 goto drop; 1332 } 1333 1334 /* We do the checksum after PCB lookup... */ 1335 len = m->m_pkthdr.len; 1336 tlen = len - toff; 1337 iptos = (ntohl(ip6->ip6_flow) >> 20) & 0xff; 1338 break; 1339 #endif 1340 default: 1341 m_freem(m); 1342 return; 1343 } 1344 1345 KASSERT(TCP_HDR_ALIGNED_P(th)); 1346 1347 /* 1348 * Check that TCP offset makes sense, 1349 * pull out TCP options and adjust length. XXX 1350 */ 1351 off = th->th_off << 2; 1352 if (off < sizeof (struct tcphdr) || off > tlen) { 1353 TCP_STATINC(TCP_STAT_RCVBADOFF); 1354 goto drop; 1355 } 1356 tlen -= off; 1357 1358 /* 1359 * tcp_input() has been modified to use tlen to mean the TCP data 1360 * length throughout the function. Other functions can use 1361 * m->m_pkthdr.len as the basis for calculating the TCP data length. 1362 * rja 1363 */ 1364 1365 if (off > sizeof (struct tcphdr)) { 1366 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, off); 1367 if (th == NULL) { 1368 TCP_STATINC(TCP_STAT_RCVSHORT); 1369 return; 1370 } 1371 /* 1372 * NOTE: ip/ip6 will not be affected by m_pulldown() 1373 * (as they're before toff) and we don't need to update those. 1374 */ 1375 KASSERT(TCP_HDR_ALIGNED_P(th)); 1376 optlen = off - sizeof (struct tcphdr); 1377 optp = ((u_int8_t *)th) + sizeof(struct tcphdr); 1378 /* 1379 * Do quick retrieval of timestamp options ("options 1380 * prediction?"). If timestamp is the only option and it's 1381 * formatted as recommended in RFC 1323 appendix A, we 1382 * quickly get the values now and not bother calling 1383 * tcp_dooptions(), etc. 1384 */ 1385 if ((optlen == TCPOLEN_TSTAMP_APPA || 1386 (optlen > TCPOLEN_TSTAMP_APPA && 1387 optp[TCPOLEN_TSTAMP_APPA] == TCPOPT_EOL)) && 1388 *(u_int32_t *)optp == htonl(TCPOPT_TSTAMP_HDR) && 1389 (th->th_flags & TH_SYN) == 0) { 1390 opti.ts_present = 1; 1391 opti.ts_val = ntohl(*(u_int32_t *)(optp + 4)); 1392 opti.ts_ecr = ntohl(*(u_int32_t *)(optp + 8)); 1393 optp = NULL; /* we've parsed the options */ 1394 } 1395 } 1396 tiflags = th->th_flags; 1397 1398 /* 1399 * Locate pcb for segment. 1400 */ 1401 findpcb: 1402 inp = NULL; 1403 #ifdef INET6 1404 in6p = NULL; 1405 #endif 1406 switch (af) { 1407 #ifdef INET 1408 case AF_INET: 1409 inp = in_pcblookup_connect(&tcbtable, ip->ip_src, th->th_sport, 1410 ip->ip_dst, th->th_dport, 1411 &vestige); 1412 if (inp == 0 && !vestige.valid) { 1413 TCP_STATINC(TCP_STAT_PCBHASHMISS); 1414 inp = in_pcblookup_bind(&tcbtable, ip->ip_dst, th->th_dport); 1415 } 1416 #ifdef INET6 1417 if (inp == 0 && !vestige.valid) { 1418 struct in6_addr s, d; 1419 1420 /* mapped addr case */ 1421 memset(&s, 0, sizeof(s)); 1422 s.s6_addr16[5] = htons(0xffff); 1423 bcopy(&ip->ip_src, &s.s6_addr32[3], sizeof(ip->ip_src)); 1424 memset(&d, 0, sizeof(d)); 1425 d.s6_addr16[5] = htons(0xffff); 1426 bcopy(&ip->ip_dst, &d.s6_addr32[3], sizeof(ip->ip_dst)); 1427 in6p = in6_pcblookup_connect(&tcbtable, &s, 1428 th->th_sport, &d, th->th_dport, 1429 0, &vestige); 1430 if (in6p == 0 && !vestige.valid) { 1431 TCP_STATINC(TCP_STAT_PCBHASHMISS); 1432 in6p = in6_pcblookup_bind(&tcbtable, &d, 1433 th->th_dport, 0); 1434 } 1435 } 1436 #endif 1437 #ifndef INET6 1438 if (inp == 0 && !vestige.valid) 1439 #else 1440 if (inp == 0 && in6p == 0 && !vestige.valid) 1441 #endif 1442 { 1443 TCP_STATINC(TCP_STAT_NOPORT); 1444 if (tcp_log_refused && 1445 (tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) { 1446 tcp4_log_refused(ip, th); 1447 } 1448 tcp_fields_to_host(th); 1449 goto dropwithreset_ratelim; 1450 } 1451 #if defined(FAST_IPSEC) 1452 if (inp && (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 #endif /*IPSEC*/ 1466 break; 1467 #endif /*INET*/ 1468 #ifdef INET6 1469 case AF_INET6: 1470 { 1471 int faith; 1472 1473 #if defined(NFAITH) && NFAITH > 0 1474 faith = faithprefix(&ip6->ip6_dst); 1475 #else 1476 faith = 0; 1477 #endif 1478 in6p = in6_pcblookup_connect(&tcbtable, &ip6->ip6_src, 1479 th->th_sport, &ip6->ip6_dst, th->th_dport, faith, &vestige); 1480 if (!in6p && !vestige.valid) { 1481 TCP_STATINC(TCP_STAT_PCBHASHMISS); 1482 in6p = in6_pcblookup_bind(&tcbtable, &ip6->ip6_dst, 1483 th->th_dport, faith); 1484 } 1485 if (!in6p && !vestige.valid) { 1486 TCP_STATINC(TCP_STAT_NOPORT); 1487 if (tcp_log_refused && 1488 (tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) { 1489 tcp6_log_refused(ip6, th); 1490 } 1491 tcp_fields_to_host(th); 1492 goto dropwithreset_ratelim; 1493 } 1494 #if defined(FAST_IPSEC) 1495 if (in6p 1496 && (in6p->in6p_socket->so_options & SO_ACCEPTCONN) == 0 1497 && ipsec6_in_reject(m, in6p)) { 1498 IPSEC6_STATINC(IPSEC_STAT_IN_POLVIO); 1499 goto drop; 1500 } 1501 #endif /*IPSEC*/ 1502 break; 1503 } 1504 #endif 1505 } 1506 1507 /* 1508 * If the state is CLOSED (i.e., TCB does not exist) then 1509 * all data in the incoming segment is discarded. 1510 * If the TCB exists but is in CLOSED state, it is embryonic, 1511 * but should either do a listen or a connect soon. 1512 */ 1513 tp = NULL; 1514 so = NULL; 1515 if (inp) { 1516 /* Check the minimum TTL for socket. */ 1517 if (ip->ip_ttl < inp->inp_ip_minttl) 1518 goto drop; 1519 1520 tp = intotcpcb(inp); 1521 so = inp->inp_socket; 1522 } 1523 #ifdef INET6 1524 else if (in6p) { 1525 tp = in6totcpcb(in6p); 1526 so = in6p->in6p_socket; 1527 } 1528 #endif 1529 else if (vestige.valid) { 1530 int mc = 0; 1531 1532 /* We do not support the resurrection of vtw tcpcps. 1533 */ 1534 if (tcp_input_checksum(af, m, th, toff, off, tlen)) 1535 goto badcsum; 1536 1537 switch (af) { 1538 #ifdef INET6 1539 case AF_INET6: 1540 mc = IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst); 1541 break; 1542 #endif 1543 1544 case AF_INET: 1545 mc = (IN_MULTICAST(ip->ip_dst.s_addr) 1546 || in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)); 1547 break; 1548 } 1549 1550 tcp_fields_to_host(th); 1551 tcp_vtw_input(th, &vestige, m, tlen, mc); 1552 m = 0; 1553 goto drop; 1554 } 1555 1556 if (tp == 0) { 1557 tcp_fields_to_host(th); 1558 goto dropwithreset_ratelim; 1559 } 1560 if (tp->t_state == TCPS_CLOSED) 1561 goto drop; 1562 1563 KASSERT(so->so_lock == softnet_lock); 1564 KASSERT(solocked(so)); 1565 1566 /* 1567 * Checksum extended TCP header and data. 1568 */ 1569 if (tcp_input_checksum(af, m, th, toff, off, tlen)) 1570 goto badcsum; 1571 1572 tcp_fields_to_host(th); 1573 1574 /* Unscale the window into a 32-bit value. */ 1575 if ((tiflags & TH_SYN) == 0) 1576 tiwin = th->th_win << tp->snd_scale; 1577 else 1578 tiwin = th->th_win; 1579 1580 #ifdef INET6 1581 /* save packet options if user wanted */ 1582 if (in6p && (in6p->in6p_flags & IN6P_CONTROLOPTS)) { 1583 if (in6p->in6p_options) { 1584 m_freem(in6p->in6p_options); 1585 in6p->in6p_options = 0; 1586 } 1587 KASSERT(ip6 != NULL); 1588 ip6_savecontrol(in6p, &in6p->in6p_options, ip6, m); 1589 } 1590 #endif 1591 1592 if (so->so_options & (SO_DEBUG|SO_ACCEPTCONN)) { 1593 union syn_cache_sa src; 1594 union syn_cache_sa dst; 1595 1596 memset(&src, 0, sizeof(src)); 1597 memset(&dst, 0, sizeof(dst)); 1598 switch (af) { 1599 #ifdef INET 1600 case AF_INET: 1601 src.sin.sin_len = sizeof(struct sockaddr_in); 1602 src.sin.sin_family = AF_INET; 1603 src.sin.sin_addr = ip->ip_src; 1604 src.sin.sin_port = th->th_sport; 1605 1606 dst.sin.sin_len = sizeof(struct sockaddr_in); 1607 dst.sin.sin_family = AF_INET; 1608 dst.sin.sin_addr = ip->ip_dst; 1609 dst.sin.sin_port = th->th_dport; 1610 break; 1611 #endif 1612 #ifdef INET6 1613 case AF_INET6: 1614 src.sin6.sin6_len = sizeof(struct sockaddr_in6); 1615 src.sin6.sin6_family = AF_INET6; 1616 src.sin6.sin6_addr = ip6->ip6_src; 1617 src.sin6.sin6_port = th->th_sport; 1618 1619 dst.sin6.sin6_len = sizeof(struct sockaddr_in6); 1620 dst.sin6.sin6_family = AF_INET6; 1621 dst.sin6.sin6_addr = ip6->ip6_dst; 1622 dst.sin6.sin6_port = th->th_dport; 1623 break; 1624 #endif /* INET6 */ 1625 default: 1626 goto badsyn; /*sanity*/ 1627 } 1628 1629 if (so->so_options & SO_DEBUG) { 1630 #ifdef TCP_DEBUG 1631 ostate = tp->t_state; 1632 #endif 1633 1634 tcp_saveti = NULL; 1635 if (iphlen + sizeof(struct tcphdr) > MHLEN) 1636 goto nosave; 1637 1638 if (m->m_len > iphlen && (m->m_flags & M_EXT) == 0) { 1639 tcp_saveti = m_copym(m, 0, iphlen, M_DONTWAIT); 1640 if (!tcp_saveti) 1641 goto nosave; 1642 } else { 1643 MGETHDR(tcp_saveti, M_DONTWAIT, MT_HEADER); 1644 if (!tcp_saveti) 1645 goto nosave; 1646 MCLAIM(m, &tcp_mowner); 1647 tcp_saveti->m_len = iphlen; 1648 m_copydata(m, 0, iphlen, 1649 mtod(tcp_saveti, void *)); 1650 } 1651 1652 if (M_TRAILINGSPACE(tcp_saveti) < sizeof(struct tcphdr)) { 1653 m_freem(tcp_saveti); 1654 tcp_saveti = NULL; 1655 } else { 1656 tcp_saveti->m_len += sizeof(struct tcphdr); 1657 memcpy(mtod(tcp_saveti, char *) + iphlen, th, 1658 sizeof(struct tcphdr)); 1659 } 1660 nosave:; 1661 } 1662 if (so->so_options & SO_ACCEPTCONN) { 1663 if ((tiflags & (TH_RST|TH_ACK|TH_SYN)) != TH_SYN) { 1664 if (tiflags & TH_RST) { 1665 syn_cache_reset(&src.sa, &dst.sa, th); 1666 } else if ((tiflags & (TH_ACK|TH_SYN)) == 1667 (TH_ACK|TH_SYN)) { 1668 /* 1669 * Received a SYN,ACK. This should 1670 * never happen while we are in 1671 * LISTEN. Send an RST. 1672 */ 1673 goto badsyn; 1674 } else if (tiflags & TH_ACK) { 1675 so = syn_cache_get(&src.sa, &dst.sa, 1676 th, toff, tlen, so, m); 1677 if (so == NULL) { 1678 /* 1679 * We don't have a SYN for 1680 * this ACK; send an RST. 1681 */ 1682 goto badsyn; 1683 } else if (so == 1684 (struct socket *)(-1)) { 1685 /* 1686 * We were unable to create 1687 * the connection. If the 1688 * 3-way handshake was 1689 * completed, and RST has 1690 * been sent to the peer. 1691 * Since the mbuf might be 1692 * in use for the reply, 1693 * do not free it. 1694 */ 1695 m = NULL; 1696 } else { 1697 /* 1698 * We have created a 1699 * full-blown connection. 1700 */ 1701 tp = NULL; 1702 inp = NULL; 1703 #ifdef INET6 1704 in6p = NULL; 1705 #endif 1706 switch (so->so_proto->pr_domain->dom_family) { 1707 #ifdef INET 1708 case AF_INET: 1709 inp = sotoinpcb(so); 1710 tp = intotcpcb(inp); 1711 break; 1712 #endif 1713 #ifdef INET6 1714 case AF_INET6: 1715 in6p = sotoin6pcb(so); 1716 tp = in6totcpcb(in6p); 1717 break; 1718 #endif 1719 } 1720 if (tp == NULL) 1721 goto badsyn; /*XXX*/ 1722 tiwin <<= tp->snd_scale; 1723 goto after_listen; 1724 } 1725 } else { 1726 /* 1727 * None of RST, SYN or ACK was set. 1728 * This is an invalid packet for a 1729 * TCB in LISTEN state. Send a RST. 1730 */ 1731 goto badsyn; 1732 } 1733 } else { 1734 /* 1735 * Received a SYN. 1736 * 1737 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN 1738 */ 1739 if (m->m_flags & (M_BCAST|M_MCAST)) 1740 goto drop; 1741 1742 switch (af) { 1743 #ifdef INET6 1744 case AF_INET6: 1745 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) 1746 goto drop; 1747 break; 1748 #endif /* INET6 */ 1749 case AF_INET: 1750 if (IN_MULTICAST(ip->ip_dst.s_addr) || 1751 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 1752 goto drop; 1753 break; 1754 } 1755 1756 #ifdef INET6 1757 /* 1758 * If deprecated address is forbidden, we do 1759 * not accept SYN to deprecated interface 1760 * address to prevent any new inbound 1761 * connection from getting established. 1762 * When we do not accept SYN, we send a TCP 1763 * RST, with deprecated source address (instead 1764 * of dropping it). We compromise it as it is 1765 * much better for peer to send a RST, and 1766 * RST will be the final packet for the 1767 * exchange. 1768 * 1769 * If we do not forbid deprecated addresses, we 1770 * accept the SYN packet. RFC2462 does not 1771 * suggest dropping SYN in this case. 1772 * If we decipher RFC2462 5.5.4, it says like 1773 * this: 1774 * 1. use of deprecated addr with existing 1775 * communication is okay - "SHOULD continue 1776 * to be used" 1777 * 2. use of it with new communication: 1778 * (2a) "SHOULD NOT be used if alternate 1779 * address with sufficient scope is 1780 * available" 1781 * (2b) nothing mentioned otherwise. 1782 * Here we fall into (2b) case as we have no 1783 * choice in our source address selection - we 1784 * must obey the peer. 1785 * 1786 * The wording in RFC2462 is confusing, and 1787 * there are multiple description text for 1788 * deprecated address handling - worse, they 1789 * are not exactly the same. I believe 5.5.4 1790 * is the best one, so we follow 5.5.4. 1791 */ 1792 if (af == AF_INET6 && !ip6_use_deprecated) { 1793 struct in6_ifaddr *ia6; 1794 if ((ia6 = in6ifa_ifpwithaddr(m->m_pkthdr.rcvif, 1795 &ip6->ip6_dst)) && 1796 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) { 1797 tp = NULL; 1798 goto dropwithreset; 1799 } 1800 } 1801 #endif 1802 1803 #if defined(FAST_IPSEC) 1804 switch (af) { 1805 #ifdef INET 1806 case AF_INET: 1807 if (ipsec4_in_reject_so(m, so)) { 1808 IPSEC_STATINC(IPSEC_STAT_IN_POLVIO); 1809 tp = NULL; 1810 goto dropwithreset; 1811 } 1812 break; 1813 #endif 1814 #ifdef INET6 1815 case AF_INET6: 1816 if (ipsec6_in_reject_so(m, so)) { 1817 IPSEC6_STATINC(IPSEC_STAT_IN_POLVIO); 1818 tp = NULL; 1819 goto dropwithreset; 1820 } 1821 break; 1822 #endif /*INET6*/ 1823 } 1824 #endif /*IPSEC*/ 1825 1826 /* 1827 * LISTEN socket received a SYN 1828 * from itself? This can't possibly 1829 * be valid; drop the packet. 1830 */ 1831 if (th->th_sport == th->th_dport) { 1832 int i; 1833 1834 switch (af) { 1835 #ifdef INET 1836 case AF_INET: 1837 i = in_hosteq(ip->ip_src, ip->ip_dst); 1838 break; 1839 #endif 1840 #ifdef INET6 1841 case AF_INET6: 1842 i = IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &ip6->ip6_dst); 1843 break; 1844 #endif 1845 default: 1846 i = 1; 1847 } 1848 if (i) { 1849 TCP_STATINC(TCP_STAT_BADSYN); 1850 goto drop; 1851 } 1852 } 1853 1854 /* 1855 * SYN looks ok; create compressed TCP 1856 * state for it. 1857 */ 1858 if (so->so_qlen <= so->so_qlimit && 1859 syn_cache_add(&src.sa, &dst.sa, th, tlen, 1860 so, m, optp, optlen, &opti)) 1861 m = NULL; 1862 } 1863 goto drop; 1864 } 1865 } 1866 1867 after_listen: 1868 #ifdef DIAGNOSTIC 1869 /* 1870 * Should not happen now that all embryonic connections 1871 * are handled with compressed state. 1872 */ 1873 if (tp->t_state == TCPS_LISTEN) 1874 panic("tcp_input: TCPS_LISTEN"); 1875 #endif 1876 1877 /* 1878 * Segment received on connection. 1879 * Reset idle time and keep-alive timer. 1880 */ 1881 tp->t_rcvtime = tcp_now; 1882 if (TCPS_HAVEESTABLISHED(tp->t_state)) 1883 TCP_TIMER_ARM(tp, TCPT_KEEP, tp->t_keepidle); 1884 1885 /* 1886 * Process options. 1887 */ 1888 #ifdef TCP_SIGNATURE 1889 if (optp || (tp->t_flags & TF_SIGNATURE)) 1890 #else 1891 if (optp) 1892 #endif 1893 if (tcp_dooptions(tp, optp, optlen, th, m, toff, &opti) < 0) 1894 goto drop; 1895 1896 if (TCP_SACK_ENABLED(tp)) { 1897 tcp_del_sackholes(tp, th); 1898 } 1899 1900 if (TCP_ECN_ALLOWED(tp)) { 1901 if (tiflags & TH_CWR) { 1902 tp->t_flags &= ~TF_ECN_SND_ECE; 1903 } 1904 switch (iptos & IPTOS_ECN_MASK) { 1905 case IPTOS_ECN_CE: 1906 tp->t_flags |= TF_ECN_SND_ECE; 1907 TCP_STATINC(TCP_STAT_ECN_CE); 1908 break; 1909 case IPTOS_ECN_ECT0: 1910 TCP_STATINC(TCP_STAT_ECN_ECT); 1911 break; 1912 case IPTOS_ECN_ECT1: 1913 /* XXX: ignore for now -- rpaulo */ 1914 break; 1915 } 1916 /* 1917 * Congestion experienced. 1918 * Ignore if we are already trying to recover. 1919 */ 1920 if ((tiflags & TH_ECE) && SEQ_GEQ(tp->snd_una, tp->snd_recover)) 1921 tp->t_congctl->cong_exp(tp); 1922 } 1923 1924 if (opti.ts_present && opti.ts_ecr) { 1925 /* 1926 * Calculate the RTT from the returned time stamp and the 1927 * connection's time base. If the time stamp is later than 1928 * the current time, or is extremely old, fall back to non-1323 1929 * RTT calculation. Since ts_rtt is unsigned, we can test both 1930 * at the same time. 1931 * 1932 * Note that ts_rtt is in units of slow ticks (500 1933 * ms). Since most earthbound RTTs are < 500 ms, 1934 * observed values will have large quantization noise. 1935 * Our smoothed RTT is then the fraction of observed 1936 * samples that are 1 tick instead of 0 (times 500 1937 * ms). 1938 * 1939 * ts_rtt is increased by 1 to denote a valid sample, 1940 * with 0 indicating an invalid measurement. This 1941 * extra 1 must be removed when ts_rtt is used, or 1942 * else an an erroneous extra 500 ms will result. 1943 */ 1944 ts_rtt = TCP_TIMESTAMP(tp) - opti.ts_ecr + 1; 1945 if (ts_rtt > TCP_PAWS_IDLE) 1946 ts_rtt = 0; 1947 } else { 1948 ts_rtt = 0; 1949 } 1950 1951 /* 1952 * Header prediction: check for the two common cases 1953 * of a uni-directional data xfer. If the packet has 1954 * no control flags, is in-sequence, the window didn't 1955 * change and we're not retransmitting, it's a 1956 * candidate. If the length is zero and the ack moved 1957 * forward, we're the sender side of the xfer. Just 1958 * free the data acked & wake any higher level process 1959 * that was blocked waiting for space. If the length 1960 * is non-zero and the ack didn't move, we're the 1961 * receiver side. If we're getting packets in-order 1962 * (the reassembly queue is empty), add the data to 1963 * the socket buffer and note that we need a delayed ack. 1964 */ 1965 if (tp->t_state == TCPS_ESTABLISHED && 1966 (tiflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ECE|TH_CWR|TH_ACK)) 1967 == TH_ACK && 1968 (!opti.ts_present || TSTMP_GEQ(opti.ts_val, tp->ts_recent)) && 1969 th->th_seq == tp->rcv_nxt && 1970 tiwin && tiwin == tp->snd_wnd && 1971 tp->snd_nxt == tp->snd_max) { 1972 1973 /* 1974 * If last ACK falls within this segment's sequence numbers, 1975 * record the timestamp. 1976 * NOTE that the test is modified according to the latest 1977 * proposal of the tcplw (at) cray.com list (Braden 1993/04/26). 1978 * 1979 * note that we already know 1980 * TSTMP_GEQ(opti.ts_val, tp->ts_recent) 1981 */ 1982 if (opti.ts_present && 1983 SEQ_LEQ(th->th_seq, tp->last_ack_sent)) { 1984 tp->ts_recent_age = tcp_now; 1985 tp->ts_recent = opti.ts_val; 1986 } 1987 1988 if (tlen == 0) { 1989 /* Ack prediction. */ 1990 if (SEQ_GT(th->th_ack, tp->snd_una) && 1991 SEQ_LEQ(th->th_ack, tp->snd_max) && 1992 tp->snd_cwnd >= tp->snd_wnd && 1993 tp->t_partialacks < 0) { 1994 /* 1995 * this is a pure ack for outstanding data. 1996 */ 1997 if (ts_rtt) 1998 tcp_xmit_timer(tp, ts_rtt - 1); 1999 else if (tp->t_rtttime && 2000 SEQ_GT(th->th_ack, tp->t_rtseq)) 2001 tcp_xmit_timer(tp, 2002 tcp_now - tp->t_rtttime); 2003 acked = th->th_ack - tp->snd_una; 2004 tcps = TCP_STAT_GETREF(); 2005 tcps[TCP_STAT_PREDACK]++; 2006 tcps[TCP_STAT_RCVACKPACK]++; 2007 tcps[TCP_STAT_RCVACKBYTE] += acked; 2008 TCP_STAT_PUTREF(); 2009 nd6_hint(tp); 2010 2011 if (acked > (tp->t_lastoff - tp->t_inoff)) 2012 tp->t_lastm = NULL; 2013 sbdrop(&so->so_snd, acked); 2014 tp->t_lastoff -= acked; 2015 2016 icmp_check(tp, th, acked); 2017 2018 tp->snd_una = th->th_ack; 2019 tp->snd_fack = tp->snd_una; 2020 if (SEQ_LT(tp->snd_high, tp->snd_una)) 2021 tp->snd_high = tp->snd_una; 2022 m_freem(m); 2023 2024 /* 2025 * If all outstanding data are acked, stop 2026 * retransmit timer, otherwise restart timer 2027 * using current (possibly backed-off) value. 2028 * If process is waiting for space, 2029 * wakeup/selnotify/signal. If data 2030 * are ready to send, let tcp_output 2031 * decide between more output or persist. 2032 */ 2033 if (tp->snd_una == tp->snd_max) 2034 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2035 else if (TCP_TIMER_ISARMED(tp, 2036 TCPT_PERSIST) == 0) 2037 TCP_TIMER_ARM(tp, TCPT_REXMT, 2038 tp->t_rxtcur); 2039 2040 sowwakeup(so); 2041 if (so->so_snd.sb_cc) { 2042 KERNEL_LOCK(1, NULL); 2043 (void) tcp_output(tp); 2044 KERNEL_UNLOCK_ONE(NULL); 2045 } 2046 if (tcp_saveti) 2047 m_freem(tcp_saveti); 2048 return; 2049 } 2050 } else if (th->th_ack == tp->snd_una && 2051 TAILQ_FIRST(&tp->segq) == NULL && 2052 tlen <= sbspace(&so->so_rcv)) { 2053 int newsize = 0; /* automatic sockbuf scaling */ 2054 2055 /* 2056 * this is a pure, in-sequence data packet 2057 * with nothing on the reassembly queue and 2058 * we have enough buffer space to take it. 2059 */ 2060 tp->rcv_nxt += tlen; 2061 tcps = TCP_STAT_GETREF(); 2062 tcps[TCP_STAT_PREDDAT]++; 2063 tcps[TCP_STAT_RCVPACK]++; 2064 tcps[TCP_STAT_RCVBYTE] += tlen; 2065 TCP_STAT_PUTREF(); 2066 nd6_hint(tp); 2067 2068 /* 2069 * Automatic sizing enables the performance of large buffers 2070 * and most of the efficiency of small ones by only allocating 2071 * space when it is needed. 2072 * 2073 * On the receive side the socket buffer memory is only rarely 2074 * used to any significant extent. This allows us to be much 2075 * more aggressive in scaling the receive socket buffer. For 2076 * the case that the buffer space is actually used to a large 2077 * extent and we run out of kernel memory we can simply drop 2078 * the new segments; TCP on the sender will just retransmit it 2079 * later. Setting the buffer size too big may only consume too 2080 * much kernel memory if the application doesn't read() from 2081 * the socket or packet loss or reordering makes use of the 2082 * reassembly queue. 2083 * 2084 * The criteria to step up the receive buffer one notch are: 2085 * 1. the number of bytes received during the time it takes 2086 * one timestamp to be reflected back to us (the RTT); 2087 * 2. received bytes per RTT is within seven eighth of the 2088 * current socket buffer size; 2089 * 3. receive buffer size has not hit maximal automatic size; 2090 * 2091 * This algorithm does one step per RTT at most and only if 2092 * we receive a bulk stream w/o packet losses or reorderings. 2093 * Shrinking the buffer during idle times is not necessary as 2094 * it doesn't consume any memory when idle. 2095 * 2096 * TODO: Only step up if the application is actually serving 2097 * the buffer to better manage the socket buffer resources. 2098 */ 2099 if (tcp_do_autorcvbuf && 2100 opti.ts_ecr && 2101 (so->so_rcv.sb_flags & SB_AUTOSIZE)) { 2102 if (opti.ts_ecr > tp->rfbuf_ts && 2103 opti.ts_ecr - tp->rfbuf_ts < PR_SLOWHZ) { 2104 if (tp->rfbuf_cnt > 2105 (so->so_rcv.sb_hiwat / 8 * 7) && 2106 so->so_rcv.sb_hiwat < 2107 tcp_autorcvbuf_max) { 2108 newsize = 2109 min(so->so_rcv.sb_hiwat + 2110 tcp_autorcvbuf_inc, 2111 tcp_autorcvbuf_max); 2112 } 2113 /* Start over with next RTT. */ 2114 tp->rfbuf_ts = 0; 2115 tp->rfbuf_cnt = 0; 2116 } else 2117 tp->rfbuf_cnt += tlen; /* add up */ 2118 } 2119 2120 /* 2121 * Drop TCP, IP headers and TCP options then add data 2122 * to socket buffer. 2123 */ 2124 if (so->so_state & SS_CANTRCVMORE) 2125 m_freem(m); 2126 else { 2127 /* 2128 * Set new socket buffer size. 2129 * Give up when limit is reached. 2130 */ 2131 if (newsize) 2132 if (!sbreserve(&so->so_rcv, 2133 newsize, so)) 2134 so->so_rcv.sb_flags &= ~SB_AUTOSIZE; 2135 m_adj(m, toff + off); 2136 sbappendstream(&so->so_rcv, m); 2137 } 2138 sorwakeup(so); 2139 tcp_setup_ack(tp, th); 2140 if (tp->t_flags & TF_ACKNOW) { 2141 KERNEL_LOCK(1, NULL); 2142 (void) tcp_output(tp); 2143 KERNEL_UNLOCK_ONE(NULL); 2144 } 2145 if (tcp_saveti) 2146 m_freem(tcp_saveti); 2147 return; 2148 } 2149 } 2150 2151 /* 2152 * Compute mbuf offset to TCP data segment. 2153 */ 2154 hdroptlen = toff + off; 2155 2156 /* 2157 * Calculate amount of space in receive window, 2158 * and then do TCP input processing. 2159 * Receive window is amount of space in rcv queue, 2160 * but not less than advertised window. 2161 */ 2162 { int win; 2163 2164 win = sbspace(&so->so_rcv); 2165 if (win < 0) 2166 win = 0; 2167 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 2168 } 2169 2170 /* Reset receive buffer auto scaling when not in bulk receive mode. */ 2171 tp->rfbuf_ts = 0; 2172 tp->rfbuf_cnt = 0; 2173 2174 switch (tp->t_state) { 2175 /* 2176 * If the state is SYN_SENT: 2177 * if seg contains an ACK, but not for our SYN, drop the input. 2178 * if seg contains a RST, then drop the connection. 2179 * if seg does not contain SYN, then drop it. 2180 * Otherwise this is an acceptable SYN segment 2181 * initialize tp->rcv_nxt and tp->irs 2182 * if seg contains ack then advance tp->snd_una 2183 * if seg contains a ECE and ECN support is enabled, the stream 2184 * is ECN capable. 2185 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 2186 * arrange for segment to be acked (eventually) 2187 * continue processing rest of data/controls, beginning with URG 2188 */ 2189 case TCPS_SYN_SENT: 2190 if ((tiflags & TH_ACK) && 2191 (SEQ_LEQ(th->th_ack, tp->iss) || 2192 SEQ_GT(th->th_ack, tp->snd_max))) 2193 goto dropwithreset; 2194 if (tiflags & TH_RST) { 2195 if (tiflags & TH_ACK) 2196 tp = tcp_drop(tp, ECONNREFUSED); 2197 goto drop; 2198 } 2199 if ((tiflags & TH_SYN) == 0) 2200 goto drop; 2201 if (tiflags & TH_ACK) { 2202 tp->snd_una = th->th_ack; 2203 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2204 tp->snd_nxt = tp->snd_una; 2205 if (SEQ_LT(tp->snd_high, tp->snd_una)) 2206 tp->snd_high = tp->snd_una; 2207 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2208 2209 if ((tiflags & TH_ECE) && tcp_do_ecn) { 2210 tp->t_flags |= TF_ECN_PERMIT; 2211 TCP_STATINC(TCP_STAT_ECN_SHS); 2212 } 2213 2214 } 2215 tp->irs = th->th_seq; 2216 tcp_rcvseqinit(tp); 2217 tp->t_flags |= TF_ACKNOW; 2218 tcp_mss_from_peer(tp, opti.maxseg); 2219 2220 /* 2221 * Initialize the initial congestion window. If we 2222 * had to retransmit the SYN, we must initialize cwnd 2223 * to 1 segment (i.e. the Loss Window). 2224 */ 2225 if (tp->t_flags & TF_SYN_REXMT) 2226 tp->snd_cwnd = tp->t_peermss; 2227 else { 2228 int ss = tcp_init_win; 2229 #ifdef INET 2230 if (inp != NULL && in_localaddr(inp->inp_faddr)) 2231 ss = tcp_init_win_local; 2232 #endif 2233 #ifdef INET6 2234 if (in6p != NULL && in6_localaddr(&in6p->in6p_faddr)) 2235 ss = tcp_init_win_local; 2236 #endif 2237 tp->snd_cwnd = TCP_INITIAL_WINDOW(ss, tp->t_peermss); 2238 } 2239 2240 tcp_rmx_rtt(tp); 2241 if (tiflags & TH_ACK) { 2242 TCP_STATINC(TCP_STAT_CONNECTS); 2243 /* 2244 * move tcp_established before soisconnected 2245 * because upcall handler can drive tcp_output 2246 * functionality. 2247 * XXX we might call soisconnected at the end of 2248 * all processing 2249 */ 2250 tcp_established(tp); 2251 soisconnected(so); 2252 /* Do window scaling on this connection? */ 2253 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2254 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2255 tp->snd_scale = tp->requested_s_scale; 2256 tp->rcv_scale = tp->request_r_scale; 2257 } 2258 TCP_REASS_LOCK(tp); 2259 (void) tcp_reass(tp, NULL, NULL, &tlen); 2260 /* 2261 * if we didn't have to retransmit the SYN, 2262 * use its rtt as our initial srtt & rtt var. 2263 */ 2264 if (tp->t_rtttime) 2265 tcp_xmit_timer(tp, tcp_now - tp->t_rtttime); 2266 } else 2267 tp->t_state = TCPS_SYN_RECEIVED; 2268 2269 /* 2270 * Advance th->th_seq to correspond to first data byte. 2271 * If data, trim to stay within window, 2272 * dropping FIN if necessary. 2273 */ 2274 th->th_seq++; 2275 if (tlen > tp->rcv_wnd) { 2276 todrop = tlen - tp->rcv_wnd; 2277 m_adj(m, -todrop); 2278 tlen = tp->rcv_wnd; 2279 tiflags &= ~TH_FIN; 2280 tcps = TCP_STAT_GETREF(); 2281 tcps[TCP_STAT_RCVPACKAFTERWIN]++; 2282 tcps[TCP_STAT_RCVBYTEAFTERWIN] += todrop; 2283 TCP_STAT_PUTREF(); 2284 } 2285 tp->snd_wl1 = th->th_seq - 1; 2286 tp->rcv_up = th->th_seq; 2287 goto step6; 2288 2289 /* 2290 * If the state is SYN_RECEIVED: 2291 * If seg contains an ACK, but not for our SYN, drop the input 2292 * and generate an RST. See page 36, rfc793 2293 */ 2294 case TCPS_SYN_RECEIVED: 2295 if ((tiflags & TH_ACK) && 2296 (SEQ_LEQ(th->th_ack, tp->iss) || 2297 SEQ_GT(th->th_ack, tp->snd_max))) 2298 goto dropwithreset; 2299 break; 2300 } 2301 2302 /* 2303 * States other than LISTEN or SYN_SENT. 2304 * First check timestamp, if present. 2305 * Then check that at least some bytes of segment are within 2306 * receive window. If segment begins before rcv_nxt, 2307 * drop leading data (and SYN); if nothing left, just ack. 2308 * 2309 * RFC 1323 PAWS: If we have a timestamp reply on this segment 2310 * and it's less than ts_recent, drop it. 2311 */ 2312 if (opti.ts_present && (tiflags & TH_RST) == 0 && tp->ts_recent && 2313 TSTMP_LT(opti.ts_val, tp->ts_recent)) { 2314 2315 /* Check to see if ts_recent is over 24 days old. */ 2316 if (tcp_now - tp->ts_recent_age > TCP_PAWS_IDLE) { 2317 /* 2318 * Invalidate ts_recent. If this segment updates 2319 * ts_recent, the age will be reset later and ts_recent 2320 * will get a valid value. If it does not, setting 2321 * ts_recent to zero will at least satisfy the 2322 * requirement that zero be placed in the timestamp 2323 * echo reply when ts_recent isn't valid. The 2324 * age isn't reset until we get a valid ts_recent 2325 * because we don't want out-of-order segments to be 2326 * dropped when ts_recent is old. 2327 */ 2328 tp->ts_recent = 0; 2329 } else { 2330 tcps = TCP_STAT_GETREF(); 2331 tcps[TCP_STAT_RCVDUPPACK]++; 2332 tcps[TCP_STAT_RCVDUPBYTE] += tlen; 2333 tcps[TCP_STAT_PAWSDROP]++; 2334 TCP_STAT_PUTREF(); 2335 tcp_new_dsack(tp, th->th_seq, tlen); 2336 goto dropafterack; 2337 } 2338 } 2339 2340 todrop = tp->rcv_nxt - th->th_seq; 2341 dupseg = false; 2342 if (todrop > 0) { 2343 if (tiflags & TH_SYN) { 2344 tiflags &= ~TH_SYN; 2345 th->th_seq++; 2346 if (th->th_urp > 1) 2347 th->th_urp--; 2348 else { 2349 tiflags &= ~TH_URG; 2350 th->th_urp = 0; 2351 } 2352 todrop--; 2353 } 2354 if (todrop > tlen || 2355 (todrop == tlen && (tiflags & TH_FIN) == 0)) { 2356 /* 2357 * Any valid FIN or RST must be to the left of the 2358 * window. At this point the FIN or RST must be a 2359 * duplicate or out of sequence; drop it. 2360 */ 2361 if (tiflags & TH_RST) 2362 goto drop; 2363 tiflags &= ~(TH_FIN|TH_RST); 2364 /* 2365 * Send an ACK to resynchronize and drop any data. 2366 * But keep on processing for RST or ACK. 2367 */ 2368 tp->t_flags |= TF_ACKNOW; 2369 todrop = tlen; 2370 dupseg = true; 2371 tcps = TCP_STAT_GETREF(); 2372 tcps[TCP_STAT_RCVDUPPACK]++; 2373 tcps[TCP_STAT_RCVDUPBYTE] += todrop; 2374 TCP_STAT_PUTREF(); 2375 } else if ((tiflags & TH_RST) && 2376 th->th_seq != tp->rcv_nxt) { 2377 /* 2378 * Test for reset before adjusting the sequence 2379 * number for overlapping data. 2380 */ 2381 goto dropafterack_ratelim; 2382 } else { 2383 tcps = TCP_STAT_GETREF(); 2384 tcps[TCP_STAT_RCVPARTDUPPACK]++; 2385 tcps[TCP_STAT_RCVPARTDUPBYTE] += todrop; 2386 TCP_STAT_PUTREF(); 2387 } 2388 tcp_new_dsack(tp, th->th_seq, todrop); 2389 hdroptlen += todrop; /*drop from head afterwards*/ 2390 th->th_seq += todrop; 2391 tlen -= todrop; 2392 if (th->th_urp > todrop) 2393 th->th_urp -= todrop; 2394 else { 2395 tiflags &= ~TH_URG; 2396 th->th_urp = 0; 2397 } 2398 } 2399 2400 /* 2401 * If new data are received on a connection after the 2402 * user processes are gone, then RST the other end. 2403 */ 2404 if ((so->so_state & SS_NOFDREF) && 2405 tp->t_state > TCPS_CLOSE_WAIT && tlen) { 2406 tp = tcp_close(tp); 2407 TCP_STATINC(TCP_STAT_RCVAFTERCLOSE); 2408 goto dropwithreset; 2409 } 2410 2411 /* 2412 * If segment ends after window, drop trailing data 2413 * (and PUSH and FIN); if nothing left, just ACK. 2414 */ 2415 todrop = (th->th_seq + tlen) - (tp->rcv_nxt+tp->rcv_wnd); 2416 if (todrop > 0) { 2417 TCP_STATINC(TCP_STAT_RCVPACKAFTERWIN); 2418 if (todrop >= tlen) { 2419 /* 2420 * The segment actually starts after the window. 2421 * th->th_seq + tlen - tp->rcv_nxt - tp->rcv_wnd >= tlen 2422 * th->th_seq - tp->rcv_nxt - tp->rcv_wnd >= 0 2423 * th->th_seq >= tp->rcv_nxt + tp->rcv_wnd 2424 */ 2425 TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, tlen); 2426 /* 2427 * If a new connection request is received 2428 * while in TIME_WAIT, drop the old connection 2429 * and start over if the sequence numbers 2430 * are above the previous ones. 2431 * 2432 * NOTE: We will checksum the packet again, and 2433 * so we need to put the header fields back into 2434 * network order! 2435 * XXX This kind of sucks, but we don't expect 2436 * XXX this to happen very often, so maybe it 2437 * XXX doesn't matter so much. 2438 */ 2439 if (tiflags & TH_SYN && 2440 tp->t_state == TCPS_TIME_WAIT && 2441 SEQ_GT(th->th_seq, tp->rcv_nxt)) { 2442 tp = tcp_close(tp); 2443 tcp_fields_to_net(th); 2444 goto findpcb; 2445 } 2446 /* 2447 * If window is closed can only take segments at 2448 * window edge, and have to drop data and PUSH from 2449 * incoming segments. Continue processing, but 2450 * remember to ack. Otherwise, drop segment 2451 * and (if not RST) ack. 2452 */ 2453 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 2454 tp->t_flags |= TF_ACKNOW; 2455 TCP_STATINC(TCP_STAT_RCVWINPROBE); 2456 } else 2457 goto dropafterack; 2458 } else 2459 TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, todrop); 2460 m_adj(m, -todrop); 2461 tlen -= todrop; 2462 tiflags &= ~(TH_PUSH|TH_FIN); 2463 } 2464 2465 /* 2466 * If last ACK falls within this segment's sequence numbers, 2467 * record the timestamp. 2468 * NOTE: 2469 * 1) That the test incorporates suggestions from the latest 2470 * proposal of the tcplw (at) cray.com list (Braden 1993/04/26). 2471 * 2) That updating only on newer timestamps interferes with 2472 * our earlier PAWS tests, so this check should be solely 2473 * predicated on the sequence space of this segment. 2474 * 3) That we modify the segment boundary check to be 2475 * Last.ACK.Sent <= SEG.SEQ + SEG.Len 2476 * instead of RFC1323's 2477 * Last.ACK.Sent < SEG.SEQ + SEG.Len, 2478 * This modified check allows us to overcome RFC1323's 2479 * limitations as described in Stevens TCP/IP Illustrated 2480 * Vol. 2 p.869. In such cases, we can still calculate the 2481 * RTT correctly when RCV.NXT == Last.ACK.Sent. 2482 */ 2483 if (opti.ts_present && 2484 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 2485 SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen + 2486 ((tiflags & (TH_SYN|TH_FIN)) != 0))) { 2487 tp->ts_recent_age = tcp_now; 2488 tp->ts_recent = opti.ts_val; 2489 } 2490 2491 /* 2492 * If the RST bit is set examine the state: 2493 * SYN_RECEIVED STATE: 2494 * If passive open, return to LISTEN state. 2495 * If active open, inform user that connection was refused. 2496 * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES: 2497 * Inform user that connection was reset, and close tcb. 2498 * CLOSING, LAST_ACK, TIME_WAIT STATES 2499 * Close the tcb. 2500 */ 2501 if (tiflags & TH_RST) { 2502 if (th->th_seq != tp->rcv_nxt) 2503 goto dropafterack_ratelim; 2504 2505 switch (tp->t_state) { 2506 case TCPS_SYN_RECEIVED: 2507 so->so_error = ECONNREFUSED; 2508 goto close; 2509 2510 case TCPS_ESTABLISHED: 2511 case TCPS_FIN_WAIT_1: 2512 case TCPS_FIN_WAIT_2: 2513 case TCPS_CLOSE_WAIT: 2514 so->so_error = ECONNRESET; 2515 close: 2516 tp->t_state = TCPS_CLOSED; 2517 TCP_STATINC(TCP_STAT_DROPS); 2518 tp = tcp_close(tp); 2519 goto drop; 2520 2521 case TCPS_CLOSING: 2522 case TCPS_LAST_ACK: 2523 case TCPS_TIME_WAIT: 2524 tp = tcp_close(tp); 2525 goto drop; 2526 } 2527 } 2528 2529 /* 2530 * Since we've covered the SYN-SENT and SYN-RECEIVED states above 2531 * we must be in a synchronized state. RFC791 states (under RST 2532 * generation) that any unacceptable segment (an out-of-order SYN 2533 * qualifies) received in a synchronized state must elicit only an 2534 * empty acknowledgment segment ... and the connection remains in 2535 * the same state. 2536 */ 2537 if (tiflags & TH_SYN) { 2538 if (tp->rcv_nxt == th->th_seq) { 2539 tcp_respond(tp, m, m, th, (tcp_seq)0, th->th_ack - 1, 2540 TH_ACK); 2541 if (tcp_saveti) 2542 m_freem(tcp_saveti); 2543 return; 2544 } 2545 2546 goto dropafterack_ratelim; 2547 } 2548 2549 /* 2550 * If the ACK bit is off we drop the segment and return. 2551 */ 2552 if ((tiflags & TH_ACK) == 0) { 2553 if (tp->t_flags & TF_ACKNOW) 2554 goto dropafterack; 2555 else 2556 goto drop; 2557 } 2558 2559 /* 2560 * Ack processing. 2561 */ 2562 switch (tp->t_state) { 2563 2564 /* 2565 * In SYN_RECEIVED state if the ack ACKs our SYN then enter 2566 * ESTABLISHED state and continue processing, otherwise 2567 * send an RST. 2568 */ 2569 case TCPS_SYN_RECEIVED: 2570 if (SEQ_GT(tp->snd_una, th->th_ack) || 2571 SEQ_GT(th->th_ack, tp->snd_max)) 2572 goto dropwithreset; 2573 TCP_STATINC(TCP_STAT_CONNECTS); 2574 soisconnected(so); 2575 tcp_established(tp); 2576 /* Do window scaling? */ 2577 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2578 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2579 tp->snd_scale = tp->requested_s_scale; 2580 tp->rcv_scale = tp->request_r_scale; 2581 } 2582 TCP_REASS_LOCK(tp); 2583 (void) tcp_reass(tp, NULL, NULL, &tlen); 2584 tp->snd_wl1 = th->th_seq - 1; 2585 /* fall into ... */ 2586 2587 /* 2588 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 2589 * ACKs. If the ack is in the range 2590 * tp->snd_una < th->th_ack <= tp->snd_max 2591 * then advance tp->snd_una to th->th_ack and drop 2592 * data from the retransmission queue. If this ACK reflects 2593 * more up to date window information we update our window information. 2594 */ 2595 case TCPS_ESTABLISHED: 2596 case TCPS_FIN_WAIT_1: 2597 case TCPS_FIN_WAIT_2: 2598 case TCPS_CLOSE_WAIT: 2599 case TCPS_CLOSING: 2600 case TCPS_LAST_ACK: 2601 case TCPS_TIME_WAIT: 2602 2603 if (SEQ_LEQ(th->th_ack, tp->snd_una)) { 2604 if (tlen == 0 && !dupseg && tiwin == tp->snd_wnd) { 2605 TCP_STATINC(TCP_STAT_RCVDUPACK); 2606 /* 2607 * If we have outstanding data (other than 2608 * a window probe), this is a completely 2609 * duplicate ack (ie, window info didn't 2610 * change), the ack is the biggest we've 2611 * seen and we've seen exactly our rexmt 2612 * threshhold of them, assume a packet 2613 * has been dropped and retransmit it. 2614 * Kludge snd_nxt & the congestion 2615 * window so we send only this one 2616 * packet. 2617 */ 2618 if (TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 || 2619 th->th_ack != tp->snd_una) 2620 tp->t_dupacks = 0; 2621 else if (tp->t_partialacks < 0 && 2622 (++tp->t_dupacks == tcprexmtthresh || 2623 TCP_FACK_FASTRECOV(tp))) { 2624 /* 2625 * Do the fast retransmit, and adjust 2626 * congestion control paramenters. 2627 */ 2628 if (tp->t_congctl->fast_retransmit(tp, th)) { 2629 /* False fast retransmit */ 2630 break; 2631 } else 2632 goto drop; 2633 } else if (tp->t_dupacks > tcprexmtthresh) { 2634 tp->snd_cwnd += tp->t_segsz; 2635 KERNEL_LOCK(1, NULL); 2636 (void) tcp_output(tp); 2637 KERNEL_UNLOCK_ONE(NULL); 2638 goto drop; 2639 } 2640 } else { 2641 /* 2642 * If the ack appears to be very old, only 2643 * allow data that is in-sequence. This 2644 * makes it somewhat more difficult to insert 2645 * forged data by guessing sequence numbers. 2646 * Sent an ack to try to update the send 2647 * sequence number on the other side. 2648 */ 2649 if (tlen && th->th_seq != tp->rcv_nxt && 2650 SEQ_LT(th->th_ack, 2651 tp->snd_una - tp->max_sndwnd)) 2652 goto dropafterack; 2653 } 2654 break; 2655 } 2656 /* 2657 * If the congestion window was inflated to account 2658 * for the other side's cached packets, retract it. 2659 */ 2660 /* XXX: make SACK have his own congestion control 2661 * struct -- rpaulo */ 2662 if (TCP_SACK_ENABLED(tp)) 2663 tcp_sack_newack(tp, th); 2664 else 2665 tp->t_congctl->fast_retransmit_newack(tp, th); 2666 if (SEQ_GT(th->th_ack, tp->snd_max)) { 2667 TCP_STATINC(TCP_STAT_RCVACKTOOMUCH); 2668 goto dropafterack; 2669 } 2670 acked = th->th_ack - tp->snd_una; 2671 tcps = TCP_STAT_GETREF(); 2672 tcps[TCP_STAT_RCVACKPACK]++; 2673 tcps[TCP_STAT_RCVACKBYTE] += acked; 2674 TCP_STAT_PUTREF(); 2675 2676 /* 2677 * If we have a timestamp reply, update smoothed 2678 * round trip time. If no timestamp is present but 2679 * transmit timer is running and timed sequence 2680 * number was acked, update smoothed round trip time. 2681 * Since we now have an rtt measurement, cancel the 2682 * timer backoff (cf., Phil Karn's retransmit alg.). 2683 * Recompute the initial retransmit timer. 2684 */ 2685 if (ts_rtt) 2686 tcp_xmit_timer(tp, ts_rtt - 1); 2687 else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) 2688 tcp_xmit_timer(tp, tcp_now - tp->t_rtttime); 2689 2690 /* 2691 * If all outstanding data is acked, stop retransmit 2692 * timer and remember to restart (more output or persist). 2693 * If there is more data to be acked, restart retransmit 2694 * timer, using current (possibly backed-off) value. 2695 */ 2696 if (th->th_ack == tp->snd_max) { 2697 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2698 needoutput = 1; 2699 } else if (TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) 2700 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 2701 2702 /* 2703 * New data has been acked, adjust the congestion window. 2704 */ 2705 tp->t_congctl->newack(tp, th); 2706 2707 nd6_hint(tp); 2708 if (acked > so->so_snd.sb_cc) { 2709 tp->snd_wnd -= so->so_snd.sb_cc; 2710 sbdrop(&so->so_snd, (int)so->so_snd.sb_cc); 2711 ourfinisacked = 1; 2712 } else { 2713 if (acked > (tp->t_lastoff - tp->t_inoff)) 2714 tp->t_lastm = NULL; 2715 sbdrop(&so->so_snd, acked); 2716 tp->t_lastoff -= acked; 2717 tp->snd_wnd -= acked; 2718 ourfinisacked = 0; 2719 } 2720 sowwakeup(so); 2721 2722 icmp_check(tp, th, acked); 2723 2724 tp->snd_una = th->th_ack; 2725 if (SEQ_GT(tp->snd_una, tp->snd_fack)) 2726 tp->snd_fack = tp->snd_una; 2727 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2728 tp->snd_nxt = tp->snd_una; 2729 if (SEQ_LT(tp->snd_high, tp->snd_una)) 2730 tp->snd_high = tp->snd_una; 2731 2732 switch (tp->t_state) { 2733 2734 /* 2735 * In FIN_WAIT_1 STATE in addition to the processing 2736 * for the ESTABLISHED state if our FIN is now acknowledged 2737 * then enter FIN_WAIT_2. 2738 */ 2739 case TCPS_FIN_WAIT_1: 2740 if (ourfinisacked) { 2741 /* 2742 * If we can't receive any more 2743 * data, then closing user can proceed. 2744 * Starting the timer is contrary to the 2745 * specification, but if we don't get a FIN 2746 * we'll hang forever. 2747 */ 2748 if (so->so_state & SS_CANTRCVMORE) { 2749 soisdisconnected(so); 2750 if (tp->t_maxidle > 0) 2751 TCP_TIMER_ARM(tp, TCPT_2MSL, 2752 tp->t_maxidle); 2753 } 2754 tp->t_state = TCPS_FIN_WAIT_2; 2755 } 2756 break; 2757 2758 /* 2759 * In CLOSING STATE in addition to the processing for 2760 * the ESTABLISHED state if the ACK acknowledges our FIN 2761 * then enter the TIME-WAIT state, otherwise ignore 2762 * the segment. 2763 */ 2764 case TCPS_CLOSING: 2765 if (ourfinisacked) { 2766 tp->t_state = TCPS_TIME_WAIT; 2767 tcp_canceltimers(tp); 2768 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * tp->t_msl); 2769 soisdisconnected(so); 2770 } 2771 break; 2772 2773 /* 2774 * In LAST_ACK, we may still be waiting for data to drain 2775 * and/or to be acked, as well as for the ack of our FIN. 2776 * If our FIN is now acknowledged, delete the TCB, 2777 * enter the closed state and return. 2778 */ 2779 case TCPS_LAST_ACK: 2780 if (ourfinisacked) { 2781 tp = tcp_close(tp); 2782 goto drop; 2783 } 2784 break; 2785 2786 /* 2787 * In TIME_WAIT state the only thing that should arrive 2788 * is a retransmission of the remote FIN. Acknowledge 2789 * it and restart the finack timer. 2790 */ 2791 case TCPS_TIME_WAIT: 2792 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * tp->t_msl); 2793 goto dropafterack; 2794 } 2795 } 2796 2797 step6: 2798 /* 2799 * Update window information. 2800 * Don't look at window if no ACK: TAC's send garbage on first SYN. 2801 */ 2802 if ((tiflags & TH_ACK) && (SEQ_LT(tp->snd_wl1, th->th_seq) || 2803 (tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) || 2804 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) { 2805 /* keep track of pure window updates */ 2806 if (tlen == 0 && 2807 tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) 2808 TCP_STATINC(TCP_STAT_RCVWINUPD); 2809 tp->snd_wnd = tiwin; 2810 tp->snd_wl1 = th->th_seq; 2811 tp->snd_wl2 = th->th_ack; 2812 if (tp->snd_wnd > tp->max_sndwnd) 2813 tp->max_sndwnd = tp->snd_wnd; 2814 needoutput = 1; 2815 } 2816 2817 /* 2818 * Process segments with URG. 2819 */ 2820 if ((tiflags & TH_URG) && th->th_urp && 2821 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2822 /* 2823 * This is a kludge, but if we receive and accept 2824 * random urgent pointers, we'll crash in 2825 * soreceive. It's hard to imagine someone 2826 * actually wanting to send this much urgent data. 2827 */ 2828 if (th->th_urp + so->so_rcv.sb_cc > sb_max) { 2829 th->th_urp = 0; /* XXX */ 2830 tiflags &= ~TH_URG; /* XXX */ 2831 goto dodata; /* XXX */ 2832 } 2833 /* 2834 * If this segment advances the known urgent pointer, 2835 * then mark the data stream. This should not happen 2836 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 2837 * a FIN has been received from the remote side. 2838 * In these states we ignore the URG. 2839 * 2840 * According to RFC961 (Assigned Protocols), 2841 * the urgent pointer points to the last octet 2842 * of urgent data. We continue, however, 2843 * to consider it to indicate the first octet 2844 * of data past the urgent section as the original 2845 * spec states (in one of two places). 2846 */ 2847 if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) { 2848 tp->rcv_up = th->th_seq + th->th_urp; 2849 so->so_oobmark = so->so_rcv.sb_cc + 2850 (tp->rcv_up - tp->rcv_nxt) - 1; 2851 if (so->so_oobmark == 0) 2852 so->so_state |= SS_RCVATMARK; 2853 sohasoutofband(so); 2854 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); 2855 } 2856 /* 2857 * Remove out of band data so doesn't get presented to user. 2858 * This can happen independent of advancing the URG pointer, 2859 * but if two URG's are pending at once, some out-of-band 2860 * data may creep in... ick. 2861 */ 2862 if (th->th_urp <= (u_int16_t) tlen 2863 #ifdef SO_OOBINLINE 2864 && (so->so_options & SO_OOBINLINE) == 0 2865 #endif 2866 ) 2867 tcp_pulloutofband(so, th, m, hdroptlen); 2868 } else 2869 /* 2870 * If no out of band data is expected, 2871 * pull receive urgent pointer along 2872 * with the receive window. 2873 */ 2874 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) 2875 tp->rcv_up = tp->rcv_nxt; 2876 dodata: /* XXX */ 2877 2878 /* 2879 * Process the segment text, merging it into the TCP sequencing queue, 2880 * and arranging for acknowledgement of receipt if necessary. 2881 * This process logically involves adjusting tp->rcv_wnd as data 2882 * is presented to the user (this happens in tcp_usrreq.c, 2883 * case PRU_RCVD). If a FIN has already been received on this 2884 * connection then we just ignore the text. 2885 */ 2886 if ((tlen || (tiflags & TH_FIN)) && 2887 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2888 /* 2889 * Insert segment ti into reassembly queue of tcp with 2890 * control block tp. Return TH_FIN if reassembly now includes 2891 * a segment with FIN. The macro form does the common case 2892 * inline (segment is the next to be received on an 2893 * established connection, and the queue is empty), 2894 * avoiding linkage into and removal from the queue and 2895 * repetition of various conversions. 2896 * Set DELACK for segments received in order, but ack 2897 * immediately when segments are out of order 2898 * (so fast retransmit can work). 2899 */ 2900 /* NOTE: this was TCP_REASS() macro, but used only once */ 2901 TCP_REASS_LOCK(tp); 2902 if (th->th_seq == tp->rcv_nxt && 2903 TAILQ_FIRST(&tp->segq) == NULL && 2904 tp->t_state == TCPS_ESTABLISHED) { 2905 tcp_setup_ack(tp, th); 2906 tp->rcv_nxt += tlen; 2907 tiflags = th->th_flags & TH_FIN; 2908 tcps = TCP_STAT_GETREF(); 2909 tcps[TCP_STAT_RCVPACK]++; 2910 tcps[TCP_STAT_RCVBYTE] += tlen; 2911 TCP_STAT_PUTREF(); 2912 nd6_hint(tp); 2913 if (so->so_state & SS_CANTRCVMORE) 2914 m_freem(m); 2915 else { 2916 m_adj(m, hdroptlen); 2917 sbappendstream(&(so)->so_rcv, m); 2918 } 2919 TCP_REASS_UNLOCK(tp); 2920 sorwakeup(so); 2921 } else { 2922 m_adj(m, hdroptlen); 2923 tiflags = tcp_reass(tp, th, m, &tlen); 2924 tp->t_flags |= TF_ACKNOW; 2925 } 2926 2927 /* 2928 * Note the amount of data that peer has sent into 2929 * our window, in order to estimate the sender's 2930 * buffer size. 2931 */ 2932 len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); 2933 } else { 2934 m_freem(m); 2935 m = NULL; 2936 tiflags &= ~TH_FIN; 2937 } 2938 2939 /* 2940 * If FIN is received ACK the FIN and let the user know 2941 * that the connection is closing. Ignore a FIN received before 2942 * the connection is fully established. 2943 */ 2944 if ((tiflags & TH_FIN) && TCPS_HAVEESTABLISHED(tp->t_state)) { 2945 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2946 socantrcvmore(so); 2947 tp->t_flags |= TF_ACKNOW; 2948 tp->rcv_nxt++; 2949 } 2950 switch (tp->t_state) { 2951 2952 /* 2953 * In ESTABLISHED STATE enter the CLOSE_WAIT state. 2954 */ 2955 case TCPS_ESTABLISHED: 2956 tp->t_state = TCPS_CLOSE_WAIT; 2957 break; 2958 2959 /* 2960 * If still in FIN_WAIT_1 STATE FIN has not been acked so 2961 * enter the CLOSING state. 2962 */ 2963 case TCPS_FIN_WAIT_1: 2964 tp->t_state = TCPS_CLOSING; 2965 break; 2966 2967 /* 2968 * In FIN_WAIT_2 state enter the TIME_WAIT state, 2969 * starting the time-wait timer, turning off the other 2970 * standard timers. 2971 */ 2972 case TCPS_FIN_WAIT_2: 2973 tp->t_state = TCPS_TIME_WAIT; 2974 tcp_canceltimers(tp); 2975 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * tp->t_msl); 2976 soisdisconnected(so); 2977 break; 2978 2979 /* 2980 * In TIME_WAIT state restart the 2 MSL time_wait timer. 2981 */ 2982 case TCPS_TIME_WAIT: 2983 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * tp->t_msl); 2984 break; 2985 } 2986 } 2987 #ifdef TCP_DEBUG 2988 if (so->so_options & SO_DEBUG) 2989 tcp_trace(TA_INPUT, ostate, tp, tcp_saveti, 0); 2990 #endif 2991 2992 /* 2993 * Return any desired output. 2994 */ 2995 if (needoutput || (tp->t_flags & TF_ACKNOW)) { 2996 KERNEL_LOCK(1, NULL); 2997 (void) tcp_output(tp); 2998 KERNEL_UNLOCK_ONE(NULL); 2999 } 3000 if (tcp_saveti) 3001 m_freem(tcp_saveti); 3002 3003 if (tp->t_state == TCPS_TIME_WAIT 3004 && (so->so_state & SS_NOFDREF) 3005 && (tp->t_inpcb || af != AF_INET) 3006 && (tp->t_in6pcb || af != AF_INET6) 3007 && ((af == AF_INET ? tcp4_vtw_enable : tcp6_vtw_enable) & 1) != 0 3008 && TAILQ_EMPTY(&tp->segq) 3009 && vtw_add(af, tp)) { 3010 ; 3011 } 3012 return; 3013 3014 badsyn: 3015 /* 3016 * Received a bad SYN. Increment counters and dropwithreset. 3017 */ 3018 TCP_STATINC(TCP_STAT_BADSYN); 3019 tp = NULL; 3020 goto dropwithreset; 3021 3022 dropafterack: 3023 /* 3024 * Generate an ACK dropping incoming segment if it occupies 3025 * sequence space, where the ACK reflects our state. 3026 */ 3027 if (tiflags & TH_RST) 3028 goto drop; 3029 goto dropafterack2; 3030 3031 dropafterack_ratelim: 3032 /* 3033 * We may want to rate-limit ACKs against SYN/RST attack. 3034 */ 3035 if (ppsratecheck(&tcp_ackdrop_ppslim_last, &tcp_ackdrop_ppslim_count, 3036 tcp_ackdrop_ppslim) == 0) { 3037 /* XXX stat */ 3038 goto drop; 3039 } 3040 /* ...fall into dropafterack2... */ 3041 3042 dropafterack2: 3043 m_freem(m); 3044 tp->t_flags |= TF_ACKNOW; 3045 KERNEL_LOCK(1, NULL); 3046 (void) tcp_output(tp); 3047 KERNEL_UNLOCK_ONE(NULL); 3048 if (tcp_saveti) 3049 m_freem(tcp_saveti); 3050 return; 3051 3052 dropwithreset_ratelim: 3053 /* 3054 * We may want to rate-limit RSTs in certain situations, 3055 * particularly if we are sending an RST in response to 3056 * an attempt to connect to or otherwise communicate with 3057 * a port for which we have no socket. 3058 */ 3059 if (ppsratecheck(&tcp_rst_ppslim_last, &tcp_rst_ppslim_count, 3060 tcp_rst_ppslim) == 0) { 3061 /* XXX stat */ 3062 goto drop; 3063 } 3064 /* ...fall into dropwithreset... */ 3065 3066 dropwithreset: 3067 /* 3068 * Generate a RST, dropping incoming segment. 3069 * Make ACK acceptable to originator of segment. 3070 */ 3071 if (tiflags & TH_RST) 3072 goto drop; 3073 3074 switch (af) { 3075 #ifdef INET6 3076 case AF_INET6: 3077 /* For following calls to tcp_respond */ 3078 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) 3079 goto drop; 3080 break; 3081 #endif /* INET6 */ 3082 case AF_INET: 3083 if (IN_MULTICAST(ip->ip_dst.s_addr) || 3084 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 3085 goto drop; 3086 } 3087 3088 if (tiflags & TH_ACK) 3089 (void)tcp_respond(tp, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 3090 else { 3091 if (tiflags & TH_SYN) 3092 tlen++; 3093 (void)tcp_respond(tp, m, m, th, th->th_seq + tlen, (tcp_seq)0, 3094 TH_RST|TH_ACK); 3095 } 3096 if (tcp_saveti) 3097 m_freem(tcp_saveti); 3098 return; 3099 3100 badcsum: 3101 drop: 3102 /* 3103 * Drop space held by incoming segment and return. 3104 */ 3105 if (tp) { 3106 if (tp->t_inpcb) 3107 so = tp->t_inpcb->inp_socket; 3108 #ifdef INET6 3109 else if (tp->t_in6pcb) 3110 so = tp->t_in6pcb->in6p_socket; 3111 #endif 3112 else 3113 so = NULL; 3114 #ifdef TCP_DEBUG 3115 if (so && (so->so_options & SO_DEBUG) != 0) 3116 tcp_trace(TA_DROP, ostate, tp, tcp_saveti, 0); 3117 #endif 3118 } 3119 if (tcp_saveti) 3120 m_freem(tcp_saveti); 3121 m_freem(m); 3122 return; 3123 } 3124 3125 #ifdef TCP_SIGNATURE 3126 int 3127 tcp_signature_apply(void *fstate, void *data, u_int len) 3128 { 3129 3130 MD5Update(fstate, (u_char *)data, len); 3131 return (0); 3132 } 3133 3134 struct secasvar * 3135 tcp_signature_getsav(struct mbuf *m, struct tcphdr *th) 3136 { 3137 struct secasvar *sav; 3138 #ifdef FAST_IPSEC 3139 union sockaddr_union dst; 3140 #endif 3141 struct ip *ip; 3142 struct ip6_hdr *ip6; 3143 3144 ip = mtod(m, struct ip *); 3145 switch (ip->ip_v) { 3146 case 4: 3147 ip = mtod(m, struct ip *); 3148 ip6 = NULL; 3149 break; 3150 case 6: 3151 ip = NULL; 3152 ip6 = mtod(m, struct ip6_hdr *); 3153 break; 3154 default: 3155 return (NULL); 3156 } 3157 3158 #ifdef FAST_IPSEC 3159 /* Extract the destination from the IP header in the mbuf. */ 3160 memset(&dst, 0, sizeof(union sockaddr_union)); 3161 if (ip !=NULL) { 3162 dst.sa.sa_len = sizeof(struct sockaddr_in); 3163 dst.sa.sa_family = AF_INET; 3164 dst.sin.sin_addr = ip->ip_dst; 3165 } else { 3166 dst.sa.sa_len = sizeof(struct sockaddr_in6); 3167 dst.sa.sa_family = AF_INET6; 3168 dst.sin6.sin6_addr = ip6->ip6_dst; 3169 } 3170 3171 /* 3172 * Look up an SADB entry which matches the address of the peer. 3173 */ 3174 sav = KEY_ALLOCSA(&dst, IPPROTO_TCP, htonl(TCP_SIG_SPI), 0, 0); 3175 #else 3176 if (ip) 3177 sav = key_allocsa(AF_INET, (void *)&ip->ip_src, 3178 (void *)&ip->ip_dst, IPPROTO_TCP, 3179 htonl(TCP_SIG_SPI), 0, 0); 3180 else 3181 sav = key_allocsa(AF_INET6, (void *)&ip6->ip6_src, 3182 (void *)&ip6->ip6_dst, IPPROTO_TCP, 3183 htonl(TCP_SIG_SPI), 0, 0); 3184 #endif 3185 3186 return (sav); /* freesav must be performed by caller */ 3187 } 3188 3189 int 3190 tcp_signature(struct mbuf *m, struct tcphdr *th, int thoff, 3191 struct secasvar *sav, char *sig) 3192 { 3193 MD5_CTX ctx; 3194 struct ip *ip; 3195 struct ipovly *ipovly; 3196 struct ip6_hdr *ip6; 3197 struct ippseudo ippseudo; 3198 struct ip6_hdr_pseudo ip6pseudo; 3199 struct tcphdr th0; 3200 int l, tcphdrlen; 3201 3202 if (sav == NULL) 3203 return (-1); 3204 3205 tcphdrlen = th->th_off * 4; 3206 3207 switch (mtod(m, struct ip *)->ip_v) { 3208 case 4: 3209 ip = mtod(m, struct ip *); 3210 ip6 = NULL; 3211 break; 3212 case 6: 3213 ip = NULL; 3214 ip6 = mtod(m, struct ip6_hdr *); 3215 break; 3216 default: 3217 return (-1); 3218 } 3219 3220 MD5Init(&ctx); 3221 3222 if (ip) { 3223 memset(&ippseudo, 0, sizeof(ippseudo)); 3224 ipovly = (struct ipovly *)ip; 3225 ippseudo.ippseudo_src = ipovly->ih_src; 3226 ippseudo.ippseudo_dst = ipovly->ih_dst; 3227 ippseudo.ippseudo_pad = 0; 3228 ippseudo.ippseudo_p = IPPROTO_TCP; 3229 ippseudo.ippseudo_len = htons(m->m_pkthdr.len - thoff); 3230 MD5Update(&ctx, (char *)&ippseudo, sizeof(ippseudo)); 3231 } else { 3232 memset(&ip6pseudo, 0, sizeof(ip6pseudo)); 3233 ip6pseudo.ip6ph_src = ip6->ip6_src; 3234 in6_clearscope(&ip6pseudo.ip6ph_src); 3235 ip6pseudo.ip6ph_dst = ip6->ip6_dst; 3236 in6_clearscope(&ip6pseudo.ip6ph_dst); 3237 ip6pseudo.ip6ph_len = htons(m->m_pkthdr.len - thoff); 3238 ip6pseudo.ip6ph_nxt = IPPROTO_TCP; 3239 MD5Update(&ctx, (char *)&ip6pseudo, sizeof(ip6pseudo)); 3240 } 3241 3242 th0 = *th; 3243 th0.th_sum = 0; 3244 MD5Update(&ctx, (char *)&th0, sizeof(th0)); 3245 3246 l = m->m_pkthdr.len - thoff - tcphdrlen; 3247 if (l > 0) 3248 m_apply(m, thoff + tcphdrlen, 3249 m->m_pkthdr.len - thoff - tcphdrlen, 3250 tcp_signature_apply, &ctx); 3251 3252 MD5Update(&ctx, _KEYBUF(sav->key_auth), _KEYLEN(sav->key_auth)); 3253 MD5Final(sig, &ctx); 3254 3255 return (0); 3256 } 3257 #endif 3258 3259 /* 3260 * tcp_dooptions: parse and process tcp options. 3261 * 3262 * returns -1 if this segment should be dropped. (eg. wrong signature) 3263 * otherwise returns 0. 3264 */ 3265 3266 static int 3267 tcp_dooptions(struct tcpcb *tp, const u_char *cp, int cnt, 3268 struct tcphdr *th, 3269 struct mbuf *m, int toff, struct tcp_opt_info *oi) 3270 { 3271 u_int16_t mss; 3272 int opt, optlen = 0; 3273 #ifdef TCP_SIGNATURE 3274 void *sigp = NULL; 3275 char sigbuf[TCP_SIGLEN]; 3276 struct secasvar *sav = NULL; 3277 #endif 3278 3279 for (; cp && cnt > 0; cnt -= optlen, cp += optlen) { 3280 opt = cp[0]; 3281 if (opt == TCPOPT_EOL) 3282 break; 3283 if (opt == TCPOPT_NOP) 3284 optlen = 1; 3285 else { 3286 if (cnt < 2) 3287 break; 3288 optlen = cp[1]; 3289 if (optlen < 2 || optlen > cnt) 3290 break; 3291 } 3292 switch (opt) { 3293 3294 default: 3295 continue; 3296 3297 case TCPOPT_MAXSEG: 3298 if (optlen != TCPOLEN_MAXSEG) 3299 continue; 3300 if (!(th->th_flags & TH_SYN)) 3301 continue; 3302 if (TCPS_HAVERCVDSYN(tp->t_state)) 3303 continue; 3304 bcopy(cp + 2, &mss, sizeof(mss)); 3305 oi->maxseg = ntohs(mss); 3306 break; 3307 3308 case TCPOPT_WINDOW: 3309 if (optlen != TCPOLEN_WINDOW) 3310 continue; 3311 if (!(th->th_flags & TH_SYN)) 3312 continue; 3313 if (TCPS_HAVERCVDSYN(tp->t_state)) 3314 continue; 3315 tp->t_flags |= TF_RCVD_SCALE; 3316 tp->requested_s_scale = cp[2]; 3317 if (tp->requested_s_scale > TCP_MAX_WINSHIFT) { 3318 #if 0 /*XXX*/ 3319 char *p; 3320 3321 if (ip) 3322 p = ntohl(ip->ip_src); 3323 #ifdef INET6 3324 else if (ip6) 3325 p = ip6_sprintf(&ip6->ip6_src); 3326 #endif 3327 else 3328 p = "(unknown)"; 3329 log(LOG_ERR, "TCP: invalid wscale %d from %s, " 3330 "assuming %d\n", 3331 tp->requested_s_scale, p, 3332 TCP_MAX_WINSHIFT); 3333 #else 3334 log(LOG_ERR, "TCP: invalid wscale %d, " 3335 "assuming %d\n", 3336 tp->requested_s_scale, 3337 TCP_MAX_WINSHIFT); 3338 #endif 3339 tp->requested_s_scale = TCP_MAX_WINSHIFT; 3340 } 3341 break; 3342 3343 case TCPOPT_TIMESTAMP: 3344 if (optlen != TCPOLEN_TIMESTAMP) 3345 continue; 3346 oi->ts_present = 1; 3347 bcopy(cp + 2, &oi->ts_val, sizeof(oi->ts_val)); 3348 NTOHL(oi->ts_val); 3349 bcopy(cp + 6, &oi->ts_ecr, sizeof(oi->ts_ecr)); 3350 NTOHL(oi->ts_ecr); 3351 3352 if (!(th->th_flags & TH_SYN)) 3353 continue; 3354 if (TCPS_HAVERCVDSYN(tp->t_state)) 3355 continue; 3356 /* 3357 * A timestamp received in a SYN makes 3358 * it ok to send timestamp requests and replies. 3359 */ 3360 tp->t_flags |= TF_RCVD_TSTMP; 3361 tp->ts_recent = oi->ts_val; 3362 tp->ts_recent_age = tcp_now; 3363 break; 3364 3365 case TCPOPT_SACK_PERMITTED: 3366 if (optlen != TCPOLEN_SACK_PERMITTED) 3367 continue; 3368 if (!(th->th_flags & TH_SYN)) 3369 continue; 3370 if (TCPS_HAVERCVDSYN(tp->t_state)) 3371 continue; 3372 if (tcp_do_sack) { 3373 tp->t_flags |= TF_SACK_PERMIT; 3374 tp->t_flags |= TF_WILL_SACK; 3375 } 3376 break; 3377 3378 case TCPOPT_SACK: 3379 tcp_sack_option(tp, th, cp, optlen); 3380 break; 3381 #ifdef TCP_SIGNATURE 3382 case TCPOPT_SIGNATURE: 3383 if (optlen != TCPOLEN_SIGNATURE) 3384 continue; 3385 if (sigp && memcmp(sigp, cp + 2, TCP_SIGLEN)) 3386 return (-1); 3387 3388 sigp = sigbuf; 3389 memcpy(sigbuf, cp + 2, TCP_SIGLEN); 3390 tp->t_flags |= TF_SIGNATURE; 3391 break; 3392 #endif 3393 } 3394 } 3395 3396 #ifdef TCP_SIGNATURE 3397 if (tp->t_flags & TF_SIGNATURE) { 3398 3399 sav = tcp_signature_getsav(m, th); 3400 3401 if (sav == NULL && tp->t_state == TCPS_LISTEN) 3402 return (-1); 3403 } 3404 3405 if ((sigp ? TF_SIGNATURE : 0) ^ (tp->t_flags & TF_SIGNATURE)) { 3406 if (sav == NULL) 3407 return (-1); 3408 #ifdef FAST_IPSEC 3409 KEY_FREESAV(&sav); 3410 #else 3411 key_freesav(sav); 3412 #endif 3413 return (-1); 3414 } 3415 3416 if (sigp) { 3417 char sig[TCP_SIGLEN]; 3418 3419 tcp_fields_to_net(th); 3420 if (tcp_signature(m, th, toff, sav, sig) < 0) { 3421 tcp_fields_to_host(th); 3422 if (sav == NULL) 3423 return (-1); 3424 #ifdef FAST_IPSEC 3425 KEY_FREESAV(&sav); 3426 #else 3427 key_freesav(sav); 3428 #endif 3429 return (-1); 3430 } 3431 tcp_fields_to_host(th); 3432 3433 if (memcmp(sig, sigp, TCP_SIGLEN)) { 3434 TCP_STATINC(TCP_STAT_BADSIG); 3435 if (sav == NULL) 3436 return (-1); 3437 #ifdef FAST_IPSEC 3438 KEY_FREESAV(&sav); 3439 #else 3440 key_freesav(sav); 3441 #endif 3442 return (-1); 3443 } else 3444 TCP_STATINC(TCP_STAT_GOODSIG); 3445 3446 key_sa_recordxfer(sav, m); 3447 #ifdef FAST_IPSEC 3448 KEY_FREESAV(&sav); 3449 #else 3450 key_freesav(sav); 3451 #endif 3452 } 3453 #endif 3454 3455 return (0); 3456 } 3457 3458 /* 3459 * Pull out of band byte out of a segment so 3460 * it doesn't appear in the user's data queue. 3461 * It is still reflected in the segment length for 3462 * sequencing purposes. 3463 */ 3464 void 3465 tcp_pulloutofband(struct socket *so, struct tcphdr *th, 3466 struct mbuf *m, int off) 3467 { 3468 int cnt = off + th->th_urp - 1; 3469 3470 while (cnt >= 0) { 3471 if (m->m_len > cnt) { 3472 char *cp = mtod(m, char *) + cnt; 3473 struct tcpcb *tp = sototcpcb(so); 3474 3475 tp->t_iobc = *cp; 3476 tp->t_oobflags |= TCPOOB_HAVEDATA; 3477 bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); 3478 m->m_len--; 3479 return; 3480 } 3481 cnt -= m->m_len; 3482 m = m->m_next; 3483 if (m == 0) 3484 break; 3485 } 3486 panic("tcp_pulloutofband"); 3487 } 3488 3489 /* 3490 * Collect new round-trip time estimate 3491 * and update averages and current timeout. 3492 * 3493 * rtt is in units of slow ticks (typically 500 ms) -- essentially the 3494 * difference of two timestamps. 3495 */ 3496 void 3497 tcp_xmit_timer(struct tcpcb *tp, uint32_t rtt) 3498 { 3499 int32_t delta; 3500 3501 TCP_STATINC(TCP_STAT_RTTUPDATED); 3502 if (tp->t_srtt != 0) { 3503 /* 3504 * Compute the amount to add to srtt for smoothing, 3505 * *alpha, or 2^(-TCP_RTT_SHIFT). Because 3506 * srtt is stored in 1/32 slow ticks, we conceptually 3507 * shift left 5 bits, subtract srtt to get the 3508 * diference, and then shift right by TCP_RTT_SHIFT 3509 * (3) to obtain 1/8 of the difference. 3510 */ 3511 delta = (rtt << 2) - (tp->t_srtt >> TCP_RTT_SHIFT); 3512 /* 3513 * This can never happen, because delta's lowest 3514 * possible value is 1/8 of t_srtt. But if it does, 3515 * set srtt to some reasonable value, here chosen 3516 * as 1/8 tick. 3517 */ 3518 if ((tp->t_srtt += delta) <= 0) 3519 tp->t_srtt = 1 << 2; 3520 /* 3521 * RFC2988 requires that rttvar be updated first. 3522 * This code is compliant because "delta" is the old 3523 * srtt minus the new observation (scaled). 3524 * 3525 * RFC2988 says: 3526 * rttvar = (1-beta) * rttvar + beta * |srtt-observed| 3527 * 3528 * delta is in units of 1/32 ticks, and has then been 3529 * divided by 8. This is equivalent to being in 1/16s 3530 * units and divided by 4. Subtract from it 1/4 of 3531 * the existing rttvar to form the (signed) amount to 3532 * adjust. 3533 */ 3534 if (delta < 0) 3535 delta = -delta; 3536 delta -= (tp->t_rttvar >> TCP_RTTVAR_SHIFT); 3537 /* 3538 * As with srtt, this should never happen. There is 3539 * no support in RFC2988 for this operation. But 1/4s 3540 * as rttvar when faced with something arguably wrong 3541 * is ok. 3542 */ 3543 if ((tp->t_rttvar += delta) <= 0) 3544 tp->t_rttvar = 1 << 2; 3545 3546 /* 3547 * If srtt exceeds .01 second, ensure we use the 'remote' MSL 3548 * Problem is: it doesn't work. Disabled by defaulting 3549 * tcp_rttlocal to 0; see corresponding code in 3550 * tcp_subr that selects local vs remote in a different way. 3551 * 3552 * The static branch prediction hint here should be removed 3553 * when the rtt estimator is fixed and the rtt_enable code 3554 * is turned back on. 3555 */ 3556 if (__predict_false(tcp_rttlocal) && tcp_msl_enable 3557 && tp->t_srtt > tcp_msl_remote_threshold 3558 && tp->t_msl < tcp_msl_remote) { 3559 tp->t_msl = tcp_msl_remote; 3560 } 3561 } else { 3562 /* 3563 * This is the first measurement. Per RFC2988, 2.2, 3564 * set rtt=R and srtt=R/2. 3565 * For srtt, storage representation is 1/32 ticks, 3566 * so shift left by 5. 3567 * For rttvar, storage representation is 1/16 ticks, 3568 * So shift left by 4, but then right by 1 to halve. 3569 */ 3570 tp->t_srtt = rtt << (TCP_RTT_SHIFT + 2); 3571 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT + 2 - 1); 3572 } 3573 tp->t_rtttime = 0; 3574 tp->t_rxtshift = 0; 3575 3576 /* 3577 * the retransmit should happen at rtt + 4 * rttvar. 3578 * Because of the way we do the smoothing, srtt and rttvar 3579 * will each average +1/2 tick of bias. When we compute 3580 * the retransmit timer, we want 1/2 tick of rounding and 3581 * 1 extra tick because of +-1/2 tick uncertainty in the 3582 * firing of the timer. The bias will give us exactly the 3583 * 1.5 tick we need. But, because the bias is 3584 * statistical, we have to test that we don't drop below 3585 * the minimum feasible timer (which is 2 ticks). 3586 */ 3587 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), 3588 max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX); 3589 3590 /* 3591 * We received an ack for a packet that wasn't retransmitted; 3592 * it is probably safe to discard any error indications we've 3593 * received recently. This isn't quite right, but close enough 3594 * for now (a route might have failed after we sent a segment, 3595 * and the return path might not be symmetrical). 3596 */ 3597 tp->t_softerror = 0; 3598 } 3599 3600 3601 /* 3602 * TCP compressed state engine. Currently used to hold compressed 3603 * state for SYN_RECEIVED. 3604 */ 3605 3606 u_long syn_cache_count; 3607 u_int32_t syn_hash1, syn_hash2; 3608 3609 #define SYN_HASH(sa, sp, dp) \ 3610 ((((sa)->s_addr^syn_hash1)*(((((u_int32_t)(dp))<<16) + \ 3611 ((u_int32_t)(sp)))^syn_hash2))) 3612 #ifndef INET6 3613 #define SYN_HASHALL(hash, src, dst) \ 3614 do { \ 3615 hash = SYN_HASH(&((const struct sockaddr_in *)(src))->sin_addr, \ 3616 ((const struct sockaddr_in *)(src))->sin_port, \ 3617 ((const struct sockaddr_in *)(dst))->sin_port); \ 3618 } while (/*CONSTCOND*/ 0) 3619 #else 3620 #define SYN_HASH6(sa, sp, dp) \ 3621 ((((sa)->s6_addr32[0] ^ (sa)->s6_addr32[3] ^ syn_hash1) * \ 3622 (((((u_int32_t)(dp))<<16) + ((u_int32_t)(sp)))^syn_hash2)) \ 3623 & 0x7fffffff) 3624 3625 #define SYN_HASHALL(hash, src, dst) \ 3626 do { \ 3627 switch ((src)->sa_family) { \ 3628 case AF_INET: \ 3629 hash = SYN_HASH(&((const struct sockaddr_in *)(src))->sin_addr, \ 3630 ((const struct sockaddr_in *)(src))->sin_port, \ 3631 ((const struct sockaddr_in *)(dst))->sin_port); \ 3632 break; \ 3633 case AF_INET6: \ 3634 hash = SYN_HASH6(&((const struct sockaddr_in6 *)(src))->sin6_addr, \ 3635 ((const struct sockaddr_in6 *)(src))->sin6_port, \ 3636 ((const struct sockaddr_in6 *)(dst))->sin6_port); \ 3637 break; \ 3638 default: \ 3639 hash = 0; \ 3640 } \ 3641 } while (/*CONSTCOND*/0) 3642 #endif /* INET6 */ 3643 3644 static struct pool syn_cache_pool; 3645 3646 /* 3647 * We don't estimate RTT with SYNs, so each packet starts with the default 3648 * RTT and each timer step has a fixed timeout value. 3649 */ 3650 #define SYN_CACHE_TIMER_ARM(sc) \ 3651 do { \ 3652 TCPT_RANGESET((sc)->sc_rxtcur, \ 3653 TCPTV_SRTTDFLT * tcp_backoff[(sc)->sc_rxtshift], TCPTV_MIN, \ 3654 TCPTV_REXMTMAX); \ 3655 callout_reset(&(sc)->sc_timer, \ 3656 (sc)->sc_rxtcur * (hz / PR_SLOWHZ), syn_cache_timer, (sc)); \ 3657 } while (/*CONSTCOND*/0) 3658 3659 #define SYN_CACHE_TIMESTAMP(sc) (tcp_now - (sc)->sc_timebase) 3660 3661 static inline void 3662 syn_cache_rm(struct syn_cache *sc) 3663 { 3664 TAILQ_REMOVE(&tcp_syn_cache[sc->sc_bucketidx].sch_bucket, 3665 sc, sc_bucketq); 3666 sc->sc_tp = NULL; 3667 LIST_REMOVE(sc, sc_tpq); 3668 tcp_syn_cache[sc->sc_bucketidx].sch_length--; 3669 callout_stop(&sc->sc_timer); 3670 syn_cache_count--; 3671 } 3672 3673 static inline void 3674 syn_cache_put(struct syn_cache *sc) 3675 { 3676 if (sc->sc_ipopts) 3677 (void) m_free(sc->sc_ipopts); 3678 rtcache_free(&sc->sc_route); 3679 sc->sc_flags |= SCF_DEAD; 3680 if (!callout_invoking(&sc->sc_timer)) 3681 callout_schedule(&(sc)->sc_timer, 1); 3682 } 3683 3684 void 3685 syn_cache_init(void) 3686 { 3687 int i; 3688 3689 pool_init(&syn_cache_pool, sizeof(struct syn_cache), 0, 0, 0, 3690 "synpl", NULL, IPL_SOFTNET); 3691 3692 /* Initialize the hash buckets. */ 3693 for (i = 0; i < tcp_syn_cache_size; i++) 3694 TAILQ_INIT(&tcp_syn_cache[i].sch_bucket); 3695 } 3696 3697 void 3698 syn_cache_insert(struct syn_cache *sc, struct tcpcb *tp) 3699 { 3700 struct syn_cache_head *scp; 3701 struct syn_cache *sc2; 3702 int s; 3703 3704 /* 3705 * If there are no entries in the hash table, reinitialize 3706 * the hash secrets. 3707 */ 3708 if (syn_cache_count == 0) { 3709 syn_hash1 = cprng_fast32(); 3710 syn_hash2 = cprng_fast32(); 3711 } 3712 3713 SYN_HASHALL(sc->sc_hash, &sc->sc_src.sa, &sc->sc_dst.sa); 3714 sc->sc_bucketidx = sc->sc_hash % tcp_syn_cache_size; 3715 scp = &tcp_syn_cache[sc->sc_bucketidx]; 3716 3717 /* 3718 * Make sure that we don't overflow the per-bucket 3719 * limit or the total cache size limit. 3720 */ 3721 s = splsoftnet(); 3722 if (scp->sch_length >= tcp_syn_bucket_limit) { 3723 TCP_STATINC(TCP_STAT_SC_BUCKETOVERFLOW); 3724 /* 3725 * The bucket is full. Toss the oldest element in the 3726 * bucket. This will be the first entry in the bucket. 3727 */ 3728 sc2 = TAILQ_FIRST(&scp->sch_bucket); 3729 #ifdef DIAGNOSTIC 3730 /* 3731 * This should never happen; we should always find an 3732 * entry in our bucket. 3733 */ 3734 if (sc2 == NULL) 3735 panic("syn_cache_insert: bucketoverflow: impossible"); 3736 #endif 3737 syn_cache_rm(sc2); 3738 syn_cache_put(sc2); /* calls pool_put but see spl above */ 3739 } else if (syn_cache_count >= tcp_syn_cache_limit) { 3740 struct syn_cache_head *scp2, *sce; 3741 3742 TCP_STATINC(TCP_STAT_SC_OVERFLOWED); 3743 /* 3744 * The cache is full. Toss the oldest entry in the 3745 * first non-empty bucket we can find. 3746 * 3747 * XXX We would really like to toss the oldest 3748 * entry in the cache, but we hope that this 3749 * condition doesn't happen very often. 3750 */ 3751 scp2 = scp; 3752 if (TAILQ_EMPTY(&scp2->sch_bucket)) { 3753 sce = &tcp_syn_cache[tcp_syn_cache_size]; 3754 for (++scp2; scp2 != scp; scp2++) { 3755 if (scp2 >= sce) 3756 scp2 = &tcp_syn_cache[0]; 3757 if (! TAILQ_EMPTY(&scp2->sch_bucket)) 3758 break; 3759 } 3760 #ifdef DIAGNOSTIC 3761 /* 3762 * This should never happen; we should always find a 3763 * non-empty bucket. 3764 */ 3765 if (scp2 == scp) 3766 panic("syn_cache_insert: cacheoverflow: " 3767 "impossible"); 3768 #endif 3769 } 3770 sc2 = TAILQ_FIRST(&scp2->sch_bucket); 3771 syn_cache_rm(sc2); 3772 syn_cache_put(sc2); /* calls pool_put but see spl above */ 3773 } 3774 3775 /* 3776 * Initialize the entry's timer. 3777 */ 3778 sc->sc_rxttot = 0; 3779 sc->sc_rxtshift = 0; 3780 SYN_CACHE_TIMER_ARM(sc); 3781 3782 /* Link it from tcpcb entry */ 3783 LIST_INSERT_HEAD(&tp->t_sc, sc, sc_tpq); 3784 3785 /* Put it into the bucket. */ 3786 TAILQ_INSERT_TAIL(&scp->sch_bucket, sc, sc_bucketq); 3787 scp->sch_length++; 3788 syn_cache_count++; 3789 3790 TCP_STATINC(TCP_STAT_SC_ADDED); 3791 splx(s); 3792 } 3793 3794 /* 3795 * Walk the timer queues, looking for SYN,ACKs that need to be retransmitted. 3796 * If we have retransmitted an entry the maximum number of times, expire 3797 * that entry. 3798 */ 3799 void 3800 syn_cache_timer(void *arg) 3801 { 3802 struct syn_cache *sc = arg; 3803 3804 mutex_enter(softnet_lock); 3805 KERNEL_LOCK(1, NULL); 3806 callout_ack(&sc->sc_timer); 3807 3808 if (__predict_false(sc->sc_flags & SCF_DEAD)) { 3809 TCP_STATINC(TCP_STAT_SC_DELAYED_FREE); 3810 callout_destroy(&sc->sc_timer); 3811 pool_put(&syn_cache_pool, sc); 3812 KERNEL_UNLOCK_ONE(NULL); 3813 mutex_exit(softnet_lock); 3814 return; 3815 } 3816 3817 if (__predict_false(sc->sc_rxtshift == TCP_MAXRXTSHIFT)) { 3818 /* Drop it -- too many retransmissions. */ 3819 goto dropit; 3820 } 3821 3822 /* 3823 * Compute the total amount of time this entry has 3824 * been on a queue. If this entry has been on longer 3825 * than the keep alive timer would allow, expire it. 3826 */ 3827 sc->sc_rxttot += sc->sc_rxtcur; 3828 if (sc->sc_rxttot >= tcp_keepinit) 3829 goto dropit; 3830 3831 TCP_STATINC(TCP_STAT_SC_RETRANSMITTED); 3832 (void) syn_cache_respond(sc, NULL); 3833 3834 /* Advance the timer back-off. */ 3835 sc->sc_rxtshift++; 3836 SYN_CACHE_TIMER_ARM(sc); 3837 3838 KERNEL_UNLOCK_ONE(NULL); 3839 mutex_exit(softnet_lock); 3840 return; 3841 3842 dropit: 3843 TCP_STATINC(TCP_STAT_SC_TIMED_OUT); 3844 syn_cache_rm(sc); 3845 if (sc->sc_ipopts) 3846 (void) m_free(sc->sc_ipopts); 3847 rtcache_free(&sc->sc_route); 3848 callout_destroy(&sc->sc_timer); 3849 pool_put(&syn_cache_pool, sc); 3850 KERNEL_UNLOCK_ONE(NULL); 3851 mutex_exit(softnet_lock); 3852 } 3853 3854 /* 3855 * Remove syn cache created by the specified tcb entry, 3856 * because this does not make sense to keep them 3857 * (if there's no tcb entry, syn cache entry will never be used) 3858 */ 3859 void 3860 syn_cache_cleanup(struct tcpcb *tp) 3861 { 3862 struct syn_cache *sc, *nsc; 3863 int s; 3864 3865 s = splsoftnet(); 3866 3867 for (sc = LIST_FIRST(&tp->t_sc); sc != NULL; sc = nsc) { 3868 nsc = LIST_NEXT(sc, sc_tpq); 3869 3870 #ifdef DIAGNOSTIC 3871 if (sc->sc_tp != tp) 3872 panic("invalid sc_tp in syn_cache_cleanup"); 3873 #endif 3874 syn_cache_rm(sc); 3875 syn_cache_put(sc); /* calls pool_put but see spl above */ 3876 } 3877 /* just for safety */ 3878 LIST_INIT(&tp->t_sc); 3879 3880 splx(s); 3881 } 3882 3883 /* 3884 * Find an entry in the syn cache. 3885 */ 3886 struct syn_cache * 3887 syn_cache_lookup(const struct sockaddr *src, const struct sockaddr *dst, 3888 struct syn_cache_head **headp) 3889 { 3890 struct syn_cache *sc; 3891 struct syn_cache_head *scp; 3892 u_int32_t hash; 3893 int s; 3894 3895 SYN_HASHALL(hash, src, dst); 3896 3897 scp = &tcp_syn_cache[hash % tcp_syn_cache_size]; 3898 *headp = scp; 3899 s = splsoftnet(); 3900 for (sc = TAILQ_FIRST(&scp->sch_bucket); sc != NULL; 3901 sc = TAILQ_NEXT(sc, sc_bucketq)) { 3902 if (sc->sc_hash != hash) 3903 continue; 3904 if (!memcmp(&sc->sc_src, src, src->sa_len) && 3905 !memcmp(&sc->sc_dst, dst, dst->sa_len)) { 3906 splx(s); 3907 return (sc); 3908 } 3909 } 3910 splx(s); 3911 return (NULL); 3912 } 3913 3914 /* 3915 * This function gets called when we receive an ACK for a 3916 * socket in the LISTEN state. We look up the connection 3917 * in the syn cache, and if its there, we pull it out of 3918 * the cache and turn it into a full-blown connection in 3919 * the SYN-RECEIVED state. 3920 * 3921 * The return values may not be immediately obvious, and their effects 3922 * can be subtle, so here they are: 3923 * 3924 * NULL SYN was not found in cache; caller should drop the 3925 * packet and send an RST. 3926 * 3927 * -1 We were unable to create the new connection, and are 3928 * aborting it. An ACK,RST is being sent to the peer 3929 * (unless we got screwey sequence numbners; see below), 3930 * because the 3-way handshake has been completed. Caller 3931 * should not free the mbuf, since we may be using it. If 3932 * we are not, we will free it. 3933 * 3934 * Otherwise, the return value is a pointer to the new socket 3935 * associated with the connection. 3936 */ 3937 struct socket * 3938 syn_cache_get(struct sockaddr *src, struct sockaddr *dst, 3939 struct tcphdr *th, unsigned int hlen, unsigned int tlen, 3940 struct socket *so, struct mbuf *m) 3941 { 3942 struct syn_cache *sc; 3943 struct syn_cache_head *scp; 3944 struct inpcb *inp = NULL; 3945 #ifdef INET6 3946 struct in6pcb *in6p = NULL; 3947 #endif 3948 struct tcpcb *tp = 0; 3949 struct mbuf *am; 3950 int s; 3951 struct socket *oso; 3952 3953 s = splsoftnet(); 3954 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 3955 splx(s); 3956 return (NULL); 3957 } 3958 3959 /* 3960 * Verify the sequence and ack numbers. Try getting the correct 3961 * response again. 3962 */ 3963 if ((th->th_ack != sc->sc_iss + 1) || 3964 SEQ_LEQ(th->th_seq, sc->sc_irs) || 3965 SEQ_GT(th->th_seq, sc->sc_irs + 1 + sc->sc_win)) { 3966 (void) syn_cache_respond(sc, m); 3967 splx(s); 3968 return ((struct socket *)(-1)); 3969 } 3970 3971 /* Remove this cache entry */ 3972 syn_cache_rm(sc); 3973 splx(s); 3974 3975 /* 3976 * Ok, create the full blown connection, and set things up 3977 * as they would have been set up if we had created the 3978 * connection when the SYN arrived. If we can't create 3979 * the connection, abort it. 3980 */ 3981 /* 3982 * inp still has the OLD in_pcb stuff, set the 3983 * v6-related flags on the new guy, too. This is 3984 * done particularly for the case where an AF_INET6 3985 * socket is bound only to a port, and a v4 connection 3986 * comes in on that port. 3987 * we also copy the flowinfo from the original pcb 3988 * to the new one. 3989 */ 3990 oso = so; 3991 so = sonewconn(so, SS_ISCONNECTED); 3992 if (so == NULL) 3993 goto resetandabort; 3994 3995 switch (so->so_proto->pr_domain->dom_family) { 3996 #ifdef INET 3997 case AF_INET: 3998 inp = sotoinpcb(so); 3999 break; 4000 #endif 4001 #ifdef INET6 4002 case AF_INET6: 4003 in6p = sotoin6pcb(so); 4004 break; 4005 #endif 4006 } 4007 switch (src->sa_family) { 4008 #ifdef INET 4009 case AF_INET: 4010 if (inp) { 4011 inp->inp_laddr = ((struct sockaddr_in *)dst)->sin_addr; 4012 inp->inp_lport = ((struct sockaddr_in *)dst)->sin_port; 4013 inp->inp_options = ip_srcroute(); 4014 in_pcbstate(inp, INP_BOUND); 4015 if (inp->inp_options == NULL) { 4016 inp->inp_options = sc->sc_ipopts; 4017 sc->sc_ipopts = NULL; 4018 } 4019 } 4020 #ifdef INET6 4021 else if (in6p) { 4022 /* IPv4 packet to AF_INET6 socket */ 4023 memset(&in6p->in6p_laddr, 0, sizeof(in6p->in6p_laddr)); 4024 in6p->in6p_laddr.s6_addr16[5] = htons(0xffff); 4025 bcopy(&((struct sockaddr_in *)dst)->sin_addr, 4026 &in6p->in6p_laddr.s6_addr32[3], 4027 sizeof(((struct sockaddr_in *)dst)->sin_addr)); 4028 in6p->in6p_lport = ((struct sockaddr_in *)dst)->sin_port; 4029 in6totcpcb(in6p)->t_family = AF_INET; 4030 if (sotoin6pcb(oso)->in6p_flags & IN6P_IPV6_V6ONLY) 4031 in6p->in6p_flags |= IN6P_IPV6_V6ONLY; 4032 else 4033 in6p->in6p_flags &= ~IN6P_IPV6_V6ONLY; 4034 in6_pcbstate(in6p, IN6P_BOUND); 4035 } 4036 #endif 4037 break; 4038 #endif 4039 #ifdef INET6 4040 case AF_INET6: 4041 if (in6p) { 4042 in6p->in6p_laddr = ((struct sockaddr_in6 *)dst)->sin6_addr; 4043 in6p->in6p_lport = ((struct sockaddr_in6 *)dst)->sin6_port; 4044 in6_pcbstate(in6p, IN6P_BOUND); 4045 } 4046 break; 4047 #endif 4048 } 4049 #ifdef INET6 4050 if (in6p && in6totcpcb(in6p)->t_family == AF_INET6 && sotoinpcb(oso)) { 4051 struct in6pcb *oin6p = sotoin6pcb(oso); 4052 /* inherit socket options from the listening socket */ 4053 in6p->in6p_flags |= (oin6p->in6p_flags & IN6P_CONTROLOPTS); 4054 if (in6p->in6p_flags & IN6P_CONTROLOPTS) { 4055 m_freem(in6p->in6p_options); 4056 in6p->in6p_options = 0; 4057 } 4058 ip6_savecontrol(in6p, &in6p->in6p_options, 4059 mtod(m, struct ip6_hdr *), m); 4060 } 4061 #endif 4062 4063 #if defined(FAST_IPSEC) 4064 /* 4065 * we make a copy of policy, instead of sharing the policy, 4066 * for better behavior in terms of SA lookup and dead SA removal. 4067 */ 4068 if (inp) { 4069 /* copy old policy into new socket's */ 4070 if (ipsec_copy_pcbpolicy(sotoinpcb(oso)->inp_sp, inp->inp_sp)) 4071 printf("tcp_input: could not copy policy\n"); 4072 } 4073 #ifdef INET6 4074 else if (in6p) { 4075 /* copy old policy into new socket's */ 4076 if (ipsec_copy_pcbpolicy(sotoin6pcb(oso)->in6p_sp, 4077 in6p->in6p_sp)) 4078 printf("tcp_input: could not copy policy\n"); 4079 } 4080 #endif 4081 #endif 4082 4083 /* 4084 * Give the new socket our cached route reference. 4085 */ 4086 if (inp) { 4087 rtcache_copy(&inp->inp_route, &sc->sc_route); 4088 rtcache_free(&sc->sc_route); 4089 } 4090 #ifdef INET6 4091 else { 4092 rtcache_copy(&in6p->in6p_route, &sc->sc_route); 4093 rtcache_free(&sc->sc_route); 4094 } 4095 #endif 4096 4097 am = m_get(M_DONTWAIT, MT_SONAME); /* XXX */ 4098 if (am == NULL) 4099 goto resetandabort; 4100 MCLAIM(am, &tcp_mowner); 4101 am->m_len = src->sa_len; 4102 bcopy(src, mtod(am, void *), src->sa_len); 4103 if (inp) { 4104 if (in_pcbconnect(inp, am, &lwp0)) { 4105 (void) m_free(am); 4106 goto resetandabort; 4107 } 4108 } 4109 #ifdef INET6 4110 else if (in6p) { 4111 if (src->sa_family == AF_INET) { 4112 /* IPv4 packet to AF_INET6 socket */ 4113 struct sockaddr_in6 *sin6; 4114 sin6 = mtod(am, struct sockaddr_in6 *); 4115 am->m_len = sizeof(*sin6); 4116 memset(sin6, 0, sizeof(*sin6)); 4117 sin6->sin6_family = AF_INET6; 4118 sin6->sin6_len = sizeof(*sin6); 4119 sin6->sin6_port = ((struct sockaddr_in *)src)->sin_port; 4120 sin6->sin6_addr.s6_addr16[5] = htons(0xffff); 4121 bcopy(&((struct sockaddr_in *)src)->sin_addr, 4122 &sin6->sin6_addr.s6_addr32[3], 4123 sizeof(sin6->sin6_addr.s6_addr32[3])); 4124 } 4125 if (in6_pcbconnect(in6p, am, NULL)) { 4126 (void) m_free(am); 4127 goto resetandabort; 4128 } 4129 } 4130 #endif 4131 else { 4132 (void) m_free(am); 4133 goto resetandabort; 4134 } 4135 (void) m_free(am); 4136 4137 if (inp) 4138 tp = intotcpcb(inp); 4139 #ifdef INET6 4140 else if (in6p) 4141 tp = in6totcpcb(in6p); 4142 #endif 4143 else 4144 tp = NULL; 4145 tp->t_flags = sototcpcb(oso)->t_flags & TF_NODELAY; 4146 if (sc->sc_request_r_scale != 15) { 4147 tp->requested_s_scale = sc->sc_requested_s_scale; 4148 tp->request_r_scale = sc->sc_request_r_scale; 4149 tp->snd_scale = sc->sc_requested_s_scale; 4150 tp->rcv_scale = sc->sc_request_r_scale; 4151 tp->t_flags |= TF_REQ_SCALE|TF_RCVD_SCALE; 4152 } 4153 if (sc->sc_flags & SCF_TIMESTAMP) 4154 tp->t_flags |= TF_REQ_TSTMP|TF_RCVD_TSTMP; 4155 tp->ts_timebase = sc->sc_timebase; 4156 4157 tp->t_template = tcp_template(tp); 4158 if (tp->t_template == 0) { 4159 tp = tcp_drop(tp, ENOBUFS); /* destroys socket */ 4160 so = NULL; 4161 m_freem(m); 4162 goto abort; 4163 } 4164 4165 tp->iss = sc->sc_iss; 4166 tp->irs = sc->sc_irs; 4167 tcp_sendseqinit(tp); 4168 tcp_rcvseqinit(tp); 4169 tp->t_state = TCPS_SYN_RECEIVED; 4170 TCP_TIMER_ARM(tp, TCPT_KEEP, tp->t_keepinit); 4171 TCP_STATINC(TCP_STAT_ACCEPTS); 4172 4173 if ((sc->sc_flags & SCF_SACK_PERMIT) && tcp_do_sack) 4174 tp->t_flags |= TF_WILL_SACK; 4175 4176 if ((sc->sc_flags & SCF_ECN_PERMIT) && tcp_do_ecn) 4177 tp->t_flags |= TF_ECN_PERMIT; 4178 4179 #ifdef TCP_SIGNATURE 4180 if (sc->sc_flags & SCF_SIGNATURE) 4181 tp->t_flags |= TF_SIGNATURE; 4182 #endif 4183 4184 /* Initialize tp->t_ourmss before we deal with the peer's! */ 4185 tp->t_ourmss = sc->sc_ourmaxseg; 4186 tcp_mss_from_peer(tp, sc->sc_peermaxseg); 4187 4188 /* 4189 * Initialize the initial congestion window. If we 4190 * had to retransmit the SYN,ACK, we must initialize cwnd 4191 * to 1 segment (i.e. the Loss Window). 4192 */ 4193 if (sc->sc_rxtshift) 4194 tp->snd_cwnd = tp->t_peermss; 4195 else { 4196 int ss = tcp_init_win; 4197 #ifdef INET 4198 if (inp != NULL && in_localaddr(inp->inp_faddr)) 4199 ss = tcp_init_win_local; 4200 #endif 4201 #ifdef INET6 4202 if (in6p != NULL && in6_localaddr(&in6p->in6p_faddr)) 4203 ss = tcp_init_win_local; 4204 #endif 4205 tp->snd_cwnd = TCP_INITIAL_WINDOW(ss, tp->t_peermss); 4206 } 4207 4208 tcp_rmx_rtt(tp); 4209 tp->snd_wl1 = sc->sc_irs; 4210 tp->rcv_up = sc->sc_irs + 1; 4211 4212 /* 4213 * This is what whould have happened in tcp_output() when 4214 * the SYN,ACK was sent. 4215 */ 4216 tp->snd_up = tp->snd_una; 4217 tp->snd_max = tp->snd_nxt = tp->iss+1; 4218 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 4219 if (sc->sc_win > 0 && SEQ_GT(tp->rcv_nxt + sc->sc_win, tp->rcv_adv)) 4220 tp->rcv_adv = tp->rcv_nxt + sc->sc_win; 4221 tp->last_ack_sent = tp->rcv_nxt; 4222 tp->t_partialacks = -1; 4223 tp->t_dupacks = 0; 4224 4225 TCP_STATINC(TCP_STAT_SC_COMPLETED); 4226 s = splsoftnet(); 4227 syn_cache_put(sc); 4228 splx(s); 4229 return (so); 4230 4231 resetandabort: 4232 (void)tcp_respond(NULL, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 4233 abort: 4234 if (so != NULL) { 4235 (void) soqremque(so, 1); 4236 (void) soabort(so); 4237 mutex_enter(softnet_lock); 4238 } 4239 s = splsoftnet(); 4240 syn_cache_put(sc); 4241 splx(s); 4242 TCP_STATINC(TCP_STAT_SC_ABORTED); 4243 return ((struct socket *)(-1)); 4244 } 4245 4246 /* 4247 * This function is called when we get a RST for a 4248 * non-existent connection, so that we can see if the 4249 * connection is in the syn cache. If it is, zap it. 4250 */ 4251 4252 void 4253 syn_cache_reset(struct sockaddr *src, struct sockaddr *dst, struct tcphdr *th) 4254 { 4255 struct syn_cache *sc; 4256 struct syn_cache_head *scp; 4257 int s = splsoftnet(); 4258 4259 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 4260 splx(s); 4261 return; 4262 } 4263 if (SEQ_LT(th->th_seq, sc->sc_irs) || 4264 SEQ_GT(th->th_seq, sc->sc_irs+1)) { 4265 splx(s); 4266 return; 4267 } 4268 syn_cache_rm(sc); 4269 TCP_STATINC(TCP_STAT_SC_RESET); 4270 syn_cache_put(sc); /* calls pool_put but see spl above */ 4271 splx(s); 4272 } 4273 4274 void 4275 syn_cache_unreach(const struct sockaddr *src, const struct sockaddr *dst, 4276 struct tcphdr *th) 4277 { 4278 struct syn_cache *sc; 4279 struct syn_cache_head *scp; 4280 int s; 4281 4282 s = splsoftnet(); 4283 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 4284 splx(s); 4285 return; 4286 } 4287 /* If the sequence number != sc_iss, then it's a bogus ICMP msg */ 4288 if (ntohl (th->th_seq) != sc->sc_iss) { 4289 splx(s); 4290 return; 4291 } 4292 4293 /* 4294 * If we've retransmitted 3 times and this is our second error, 4295 * we remove the entry. Otherwise, we allow it to continue on. 4296 * This prevents us from incorrectly nuking an entry during a 4297 * spurious network outage. 4298 * 4299 * See tcp_notify(). 4300 */ 4301 if ((sc->sc_flags & SCF_UNREACH) == 0 || sc->sc_rxtshift < 3) { 4302 sc->sc_flags |= SCF_UNREACH; 4303 splx(s); 4304 return; 4305 } 4306 4307 syn_cache_rm(sc); 4308 TCP_STATINC(TCP_STAT_SC_UNREACH); 4309 syn_cache_put(sc); /* calls pool_put but see spl above */ 4310 splx(s); 4311 } 4312 4313 /* 4314 * Given a LISTEN socket and an inbound SYN request, add 4315 * this to the syn cache, and send back a segment: 4316 * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK> 4317 * to the source. 4318 * 4319 * IMPORTANT NOTE: We do _NOT_ ACK data that might accompany the SYN. 4320 * Doing so would require that we hold onto the data and deliver it 4321 * to the application. However, if we are the target of a SYN-flood 4322 * DoS attack, an attacker could send data which would eventually 4323 * consume all available buffer space if it were ACKed. By not ACKing 4324 * the data, we avoid this DoS scenario. 4325 */ 4326 4327 int 4328 syn_cache_add(struct sockaddr *src, struct sockaddr *dst, struct tcphdr *th, 4329 unsigned int hlen, struct socket *so, struct mbuf *m, u_char *optp, 4330 int optlen, struct tcp_opt_info *oi) 4331 { 4332 struct tcpcb tb, *tp; 4333 long win; 4334 struct syn_cache *sc; 4335 struct syn_cache_head *scp; 4336 struct mbuf *ipopts; 4337 struct tcp_opt_info opti; 4338 int s; 4339 4340 tp = sototcpcb(so); 4341 4342 memset(&opti, 0, sizeof(opti)); 4343 4344 /* 4345 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN 4346 * 4347 * Note this check is performed in tcp_input() very early on. 4348 */ 4349 4350 /* 4351 * Initialize some local state. 4352 */ 4353 win = sbspace(&so->so_rcv); 4354 if (win > TCP_MAXWIN) 4355 win = TCP_MAXWIN; 4356 4357 switch (src->sa_family) { 4358 #ifdef INET 4359 case AF_INET: 4360 /* 4361 * Remember the IP options, if any. 4362 */ 4363 ipopts = ip_srcroute(); 4364 break; 4365 #endif 4366 default: 4367 ipopts = NULL; 4368 } 4369 4370 #ifdef TCP_SIGNATURE 4371 if (optp || (tp->t_flags & TF_SIGNATURE)) 4372 #else 4373 if (optp) 4374 #endif 4375 { 4376 tb.t_flags = tcp_do_rfc1323 ? (TF_REQ_SCALE|TF_REQ_TSTMP) : 0; 4377 #ifdef TCP_SIGNATURE 4378 tb.t_flags |= (tp->t_flags & TF_SIGNATURE); 4379 #endif 4380 tb.t_state = TCPS_LISTEN; 4381 if (tcp_dooptions(&tb, optp, optlen, th, m, m->m_pkthdr.len - 4382 sizeof(struct tcphdr) - optlen - hlen, oi) < 0) 4383 return (0); 4384 } else 4385 tb.t_flags = 0; 4386 4387 /* 4388 * See if we already have an entry for this connection. 4389 * If we do, resend the SYN,ACK. We do not count this 4390 * as a retransmission (XXX though maybe we should). 4391 */ 4392 if ((sc = syn_cache_lookup(src, dst, &scp)) != NULL) { 4393 TCP_STATINC(TCP_STAT_SC_DUPESYN); 4394 if (ipopts) { 4395 /* 4396 * If we were remembering a previous source route, 4397 * forget it and use the new one we've been given. 4398 */ 4399 if (sc->sc_ipopts) 4400 (void) m_free(sc->sc_ipopts); 4401 sc->sc_ipopts = ipopts; 4402 } 4403 sc->sc_timestamp = tb.ts_recent; 4404 if (syn_cache_respond(sc, m) == 0) { 4405 uint64_t *tcps = TCP_STAT_GETREF(); 4406 tcps[TCP_STAT_SNDACKS]++; 4407 tcps[TCP_STAT_SNDTOTAL]++; 4408 TCP_STAT_PUTREF(); 4409 } 4410 return (1); 4411 } 4412 4413 s = splsoftnet(); 4414 sc = pool_get(&syn_cache_pool, PR_NOWAIT); 4415 splx(s); 4416 if (sc == NULL) { 4417 if (ipopts) 4418 (void) m_free(ipopts); 4419 return (0); 4420 } 4421 4422 /* 4423 * Fill in the cache, and put the necessary IP and TCP 4424 * options into the reply. 4425 */ 4426 memset(sc, 0, sizeof(struct syn_cache)); 4427 callout_init(&sc->sc_timer, CALLOUT_MPSAFE); 4428 bcopy(src, &sc->sc_src, src->sa_len); 4429 bcopy(dst, &sc->sc_dst, dst->sa_len); 4430 sc->sc_flags = 0; 4431 sc->sc_ipopts = ipopts; 4432 sc->sc_irs = th->th_seq; 4433 switch (src->sa_family) { 4434 #ifdef INET 4435 case AF_INET: 4436 { 4437 struct sockaddr_in *srcin = (void *) src; 4438 struct sockaddr_in *dstin = (void *) dst; 4439 4440 sc->sc_iss = tcp_new_iss1(&dstin->sin_addr, 4441 &srcin->sin_addr, dstin->sin_port, 4442 srcin->sin_port, sizeof(dstin->sin_addr), 0); 4443 break; 4444 } 4445 #endif /* INET */ 4446 #ifdef INET6 4447 case AF_INET6: 4448 { 4449 struct sockaddr_in6 *srcin6 = (void *) src; 4450 struct sockaddr_in6 *dstin6 = (void *) dst; 4451 4452 sc->sc_iss = tcp_new_iss1(&dstin6->sin6_addr, 4453 &srcin6->sin6_addr, dstin6->sin6_port, 4454 srcin6->sin6_port, sizeof(dstin6->sin6_addr), 0); 4455 break; 4456 } 4457 #endif /* INET6 */ 4458 } 4459 sc->sc_peermaxseg = oi->maxseg; 4460 sc->sc_ourmaxseg = tcp_mss_to_advertise(m->m_flags & M_PKTHDR ? 4461 m->m_pkthdr.rcvif : NULL, 4462 sc->sc_src.sa.sa_family); 4463 sc->sc_win = win; 4464 sc->sc_timebase = tcp_now - 1; /* see tcp_newtcpcb() */ 4465 sc->sc_timestamp = tb.ts_recent; 4466 if ((tb.t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP)) == 4467 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) 4468 sc->sc_flags |= SCF_TIMESTAMP; 4469 if ((tb.t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 4470 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 4471 sc->sc_requested_s_scale = tb.requested_s_scale; 4472 sc->sc_request_r_scale = 0; 4473 /* 4474 * Pick the smallest possible scaling factor that 4475 * will still allow us to scale up to sb_max. 4476 * 4477 * We do this because there are broken firewalls that 4478 * will corrupt the window scale option, leading to 4479 * the other endpoint believing that our advertised 4480 * window is unscaled. At scale factors larger than 4481 * 5 the unscaled window will drop below 1500 bytes, 4482 * leading to serious problems when traversing these 4483 * broken firewalls. 4484 * 4485 * With the default sbmax of 256K, a scale factor 4486 * of 3 will be chosen by this algorithm. Those who 4487 * choose a larger sbmax should watch out 4488 * for the compatiblity problems mentioned above. 4489 * 4490 * RFC1323: The Window field in a SYN (i.e., a <SYN> 4491 * or <SYN,ACK>) segment itself is never scaled. 4492 */ 4493 while (sc->sc_request_r_scale < TCP_MAX_WINSHIFT && 4494 (TCP_MAXWIN << sc->sc_request_r_scale) < sb_max) 4495 sc->sc_request_r_scale++; 4496 } else { 4497 sc->sc_requested_s_scale = 15; 4498 sc->sc_request_r_scale = 15; 4499 } 4500 if ((tb.t_flags & TF_SACK_PERMIT) && tcp_do_sack) 4501 sc->sc_flags |= SCF_SACK_PERMIT; 4502 4503 /* 4504 * ECN setup packet recieved. 4505 */ 4506 if ((th->th_flags & (TH_ECE|TH_CWR)) && tcp_do_ecn) 4507 sc->sc_flags |= SCF_ECN_PERMIT; 4508 4509 #ifdef TCP_SIGNATURE 4510 if (tb.t_flags & TF_SIGNATURE) 4511 sc->sc_flags |= SCF_SIGNATURE; 4512 #endif 4513 sc->sc_tp = tp; 4514 if (syn_cache_respond(sc, m) == 0) { 4515 uint64_t *tcps = TCP_STAT_GETREF(); 4516 tcps[TCP_STAT_SNDACKS]++; 4517 tcps[TCP_STAT_SNDTOTAL]++; 4518 TCP_STAT_PUTREF(); 4519 syn_cache_insert(sc, tp); 4520 } else { 4521 s = splsoftnet(); 4522 /* 4523 * syn_cache_put() will try to schedule the timer, so 4524 * we need to initialize it 4525 */ 4526 SYN_CACHE_TIMER_ARM(sc); 4527 syn_cache_put(sc); 4528 splx(s); 4529 TCP_STATINC(TCP_STAT_SC_DROPPED); 4530 } 4531 return (1); 4532 } 4533 4534 /* 4535 * syn_cache_respond: (re)send SYN+ACK. 4536 * 4537 * returns 0 on success. otherwise returns an errno, typically ENOBUFS. 4538 */ 4539 4540 int 4541 syn_cache_respond(struct syn_cache *sc, struct mbuf *m) 4542 { 4543 #ifdef INET6 4544 struct rtentry *rt; 4545 #endif 4546 struct route *ro; 4547 u_int8_t *optp; 4548 int optlen, error; 4549 u_int16_t tlen; 4550 struct ip *ip = NULL; 4551 #ifdef INET6 4552 struct ip6_hdr *ip6 = NULL; 4553 #endif 4554 struct tcpcb *tp = NULL; 4555 struct tcphdr *th; 4556 u_int hlen; 4557 struct socket *so; 4558 4559 ro = &sc->sc_route; 4560 switch (sc->sc_src.sa.sa_family) { 4561 case AF_INET: 4562 hlen = sizeof(struct ip); 4563 break; 4564 #ifdef INET6 4565 case AF_INET6: 4566 hlen = sizeof(struct ip6_hdr); 4567 break; 4568 #endif 4569 default: 4570 if (m) 4571 m_freem(m); 4572 return (EAFNOSUPPORT); 4573 } 4574 4575 /* Compute the size of the TCP options. */ 4576 optlen = 4 + (sc->sc_request_r_scale != 15 ? 4 : 0) + 4577 ((sc->sc_flags & SCF_SACK_PERMIT) ? (TCPOLEN_SACK_PERMITTED + 2) : 0) + 4578 #ifdef TCP_SIGNATURE 4579 ((sc->sc_flags & SCF_SIGNATURE) ? (TCPOLEN_SIGNATURE + 2) : 0) + 4580 #endif 4581 ((sc->sc_flags & SCF_TIMESTAMP) ? TCPOLEN_TSTAMP_APPA : 0); 4582 4583 tlen = hlen + sizeof(struct tcphdr) + optlen; 4584 4585 /* 4586 * Create the IP+TCP header from scratch. 4587 */ 4588 if (m) 4589 m_freem(m); 4590 #ifdef DIAGNOSTIC 4591 if (max_linkhdr + tlen > MCLBYTES) 4592 return (ENOBUFS); 4593 #endif 4594 MGETHDR(m, M_DONTWAIT, MT_DATA); 4595 if (m && (max_linkhdr + tlen) > MHLEN) { 4596 MCLGET(m, M_DONTWAIT); 4597 if ((m->m_flags & M_EXT) == 0) { 4598 m_freem(m); 4599 m = NULL; 4600 } 4601 } 4602 if (m == NULL) 4603 return (ENOBUFS); 4604 MCLAIM(m, &tcp_tx_mowner); 4605 4606 /* Fixup the mbuf. */ 4607 m->m_data += max_linkhdr; 4608 m->m_len = m->m_pkthdr.len = tlen; 4609 if (sc->sc_tp) { 4610 tp = sc->sc_tp; 4611 if (tp->t_inpcb) 4612 so = tp->t_inpcb->inp_socket; 4613 #ifdef INET6 4614 else if (tp->t_in6pcb) 4615 so = tp->t_in6pcb->in6p_socket; 4616 #endif 4617 else 4618 so = NULL; 4619 } else 4620 so = NULL; 4621 m->m_pkthdr.rcvif = NULL; 4622 memset(mtod(m, u_char *), 0, tlen); 4623 4624 switch (sc->sc_src.sa.sa_family) { 4625 case AF_INET: 4626 ip = mtod(m, struct ip *); 4627 ip->ip_v = 4; 4628 ip->ip_dst = sc->sc_src.sin.sin_addr; 4629 ip->ip_src = sc->sc_dst.sin.sin_addr; 4630 ip->ip_p = IPPROTO_TCP; 4631 th = (struct tcphdr *)(ip + 1); 4632 th->th_dport = sc->sc_src.sin.sin_port; 4633 th->th_sport = sc->sc_dst.sin.sin_port; 4634 break; 4635 #ifdef INET6 4636 case AF_INET6: 4637 ip6 = mtod(m, struct ip6_hdr *); 4638 ip6->ip6_vfc = IPV6_VERSION; 4639 ip6->ip6_dst = sc->sc_src.sin6.sin6_addr; 4640 ip6->ip6_src = sc->sc_dst.sin6.sin6_addr; 4641 ip6->ip6_nxt = IPPROTO_TCP; 4642 /* ip6_plen will be updated in ip6_output() */ 4643 th = (struct tcphdr *)(ip6 + 1); 4644 th->th_dport = sc->sc_src.sin6.sin6_port; 4645 th->th_sport = sc->sc_dst.sin6.sin6_port; 4646 break; 4647 #endif 4648 default: 4649 th = NULL; 4650 } 4651 4652 th->th_seq = htonl(sc->sc_iss); 4653 th->th_ack = htonl(sc->sc_irs + 1); 4654 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 4655 th->th_flags = TH_SYN|TH_ACK; 4656 th->th_win = htons(sc->sc_win); 4657 /* th_sum already 0 */ 4658 /* th_urp already 0 */ 4659 4660 /* Tack on the TCP options. */ 4661 optp = (u_int8_t *)(th + 1); 4662 *optp++ = TCPOPT_MAXSEG; 4663 *optp++ = 4; 4664 *optp++ = (sc->sc_ourmaxseg >> 8) & 0xff; 4665 *optp++ = sc->sc_ourmaxseg & 0xff; 4666 4667 if (sc->sc_request_r_scale != 15) { 4668 *((u_int32_t *)optp) = htonl(TCPOPT_NOP << 24 | 4669 TCPOPT_WINDOW << 16 | TCPOLEN_WINDOW << 8 | 4670 sc->sc_request_r_scale); 4671 optp += 4; 4672 } 4673 4674 if (sc->sc_flags & SCF_TIMESTAMP) { 4675 u_int32_t *lp = (u_int32_t *)(optp); 4676 /* Form timestamp option as shown in appendix A of RFC 1323. */ 4677 *lp++ = htonl(TCPOPT_TSTAMP_HDR); 4678 *lp++ = htonl(SYN_CACHE_TIMESTAMP(sc)); 4679 *lp = htonl(sc->sc_timestamp); 4680 optp += TCPOLEN_TSTAMP_APPA; 4681 } 4682 4683 if (sc->sc_flags & SCF_SACK_PERMIT) { 4684 u_int8_t *p = optp; 4685 4686 /* Let the peer know that we will SACK. */ 4687 p[0] = TCPOPT_SACK_PERMITTED; 4688 p[1] = 2; 4689 p[2] = TCPOPT_NOP; 4690 p[3] = TCPOPT_NOP; 4691 optp += 4; 4692 } 4693 4694 /* 4695 * Send ECN SYN-ACK setup packet. 4696 * Routes can be asymetric, so, even if we receive a packet 4697 * with ECE and CWR set, we must not assume no one will block 4698 * the ECE packet we are about to send. 4699 */ 4700 if ((sc->sc_flags & SCF_ECN_PERMIT) && tp && 4701 SEQ_GEQ(tp->snd_nxt, tp->snd_max)) { 4702 th->th_flags |= TH_ECE; 4703 TCP_STATINC(TCP_STAT_ECN_SHS); 4704 4705 /* 4706 * draft-ietf-tcpm-ecnsyn-00.txt 4707 * 4708 * "[...] a TCP node MAY respond to an ECN-setup 4709 * SYN packet by setting ECT in the responding 4710 * ECN-setup SYN/ACK packet, indicating to routers 4711 * that the SYN/ACK packet is ECN-Capable. 4712 * This allows a congested router along the path 4713 * to mark the packet instead of dropping the 4714 * packet as an indication of congestion." 4715 * 4716 * "[...] There can be a great benefit in setting 4717 * an ECN-capable codepoint in SYN/ACK packets [...] 4718 * Congestion is most likely to occur in 4719 * the server-to-client direction. As a result, 4720 * setting an ECN-capable codepoint in SYN/ACK 4721 * packets can reduce the occurence of three-second 4722 * retransmit timeouts resulting from the drop 4723 * of SYN/ACK packets." 4724 * 4725 * Page 4 and 6, January 2006. 4726 */ 4727 4728 switch (sc->sc_src.sa.sa_family) { 4729 #ifdef INET 4730 case AF_INET: 4731 ip->ip_tos |= IPTOS_ECN_ECT0; 4732 break; 4733 #endif 4734 #ifdef INET6 4735 case AF_INET6: 4736 ip6->ip6_flow |= htonl(IPTOS_ECN_ECT0 << 20); 4737 break; 4738 #endif 4739 } 4740 TCP_STATINC(TCP_STAT_ECN_ECT); 4741 } 4742 4743 #ifdef TCP_SIGNATURE 4744 if (sc->sc_flags & SCF_SIGNATURE) { 4745 struct secasvar *sav; 4746 u_int8_t *sigp; 4747 4748 sav = tcp_signature_getsav(m, th); 4749 4750 if (sav == NULL) { 4751 if (m) 4752 m_freem(m); 4753 return (EPERM); 4754 } 4755 4756 *optp++ = TCPOPT_SIGNATURE; 4757 *optp++ = TCPOLEN_SIGNATURE; 4758 sigp = optp; 4759 memset(optp, 0, TCP_SIGLEN); 4760 optp += TCP_SIGLEN; 4761 *optp++ = TCPOPT_NOP; 4762 *optp++ = TCPOPT_EOL; 4763 4764 (void)tcp_signature(m, th, hlen, sav, sigp); 4765 4766 key_sa_recordxfer(sav, m); 4767 #ifdef FAST_IPSEC 4768 KEY_FREESAV(&sav); 4769 #else 4770 key_freesav(sav); 4771 #endif 4772 } 4773 #endif 4774 4775 /* Compute the packet's checksum. */ 4776 switch (sc->sc_src.sa.sa_family) { 4777 case AF_INET: 4778 ip->ip_len = htons(tlen - hlen); 4779 th->th_sum = 0; 4780 th->th_sum = in4_cksum(m, IPPROTO_TCP, hlen, tlen - hlen); 4781 break; 4782 #ifdef INET6 4783 case AF_INET6: 4784 ip6->ip6_plen = htons(tlen - hlen); 4785 th->th_sum = 0; 4786 th->th_sum = in6_cksum(m, IPPROTO_TCP, hlen, tlen - hlen); 4787 break; 4788 #endif 4789 } 4790 4791 /* 4792 * Fill in some straggling IP bits. Note the stack expects 4793 * ip_len to be in host order, for convenience. 4794 */ 4795 switch (sc->sc_src.sa.sa_family) { 4796 #ifdef INET 4797 case AF_INET: 4798 ip->ip_len = htons(tlen); 4799 ip->ip_ttl = ip_defttl; 4800 /* XXX tos? */ 4801 break; 4802 #endif 4803 #ifdef INET6 4804 case AF_INET6: 4805 ip6->ip6_vfc &= ~IPV6_VERSION_MASK; 4806 ip6->ip6_vfc |= IPV6_VERSION; 4807 ip6->ip6_plen = htons(tlen - hlen); 4808 /* ip6_hlim will be initialized afterwards */ 4809 /* XXX flowlabel? */ 4810 break; 4811 #endif 4812 } 4813 4814 /* XXX use IPsec policy on listening socket, on SYN ACK */ 4815 tp = sc->sc_tp; 4816 4817 switch (sc->sc_src.sa.sa_family) { 4818 #ifdef INET 4819 case AF_INET: 4820 error = ip_output(m, sc->sc_ipopts, ro, 4821 (ip_mtudisc ? IP_MTUDISC : 0), 4822 NULL, so); 4823 break; 4824 #endif 4825 #ifdef INET6 4826 case AF_INET6: 4827 ip6->ip6_hlim = in6_selecthlim(NULL, 4828 (rt = rtcache_validate(ro)) != NULL ? rt->rt_ifp 4829 : NULL); 4830 4831 error = ip6_output(m, NULL /*XXX*/, ro, 0, NULL, so, NULL); 4832 break; 4833 #endif 4834 default: 4835 error = EAFNOSUPPORT; 4836 break; 4837 } 4838 return (error); 4839 } 4840
Indexes created Fri Sep 26 20:09:58 GMT 2025