tcp_input.c revision 1.316
1 /* $NetBSD: tcp_input.c,v 1.316 2011/08/31 18:31:03 plunky 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 1.316 2011/08/31 18:31:03 plunky 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 */ 174 175 #include <net/if.h> 176 #include <net/route.h> 177 #include <net/if_types.h> 178 179 #include <netinet/in.h> 180 #include <netinet/in_systm.h> 181 #include <netinet/ip.h> 182 #include <netinet/in_pcb.h> 183 #include <netinet/in_var.h> 184 #include <netinet/ip_var.h> 185 #include <netinet/in_offload.h> 186 187 #ifdef INET6 188 #ifndef INET 189 #include <netinet/in.h> 190 #endif 191 #include <netinet/ip6.h> 192 #include <netinet6/ip6_var.h> 193 #include <netinet6/in6_pcb.h> 194 #include <netinet6/ip6_var.h> 195 #include <netinet6/in6_var.h> 196 #include <netinet/icmp6.h> 197 #include <netinet6/nd6.h> 198 #ifdef TCP_SIGNATURE 199 #include <netinet6/scope6_var.h> 200 #endif 201 #endif 202 203 #ifndef INET6 204 /* always need ip6.h for IP6_EXTHDR_GET */ 205 #include <netinet/ip6.h> 206 #endif 207 208 #include <netinet/tcp.h> 209 #include <netinet/tcp_fsm.h> 210 #include <netinet/tcp_seq.h> 211 #include <netinet/tcp_timer.h> 212 #include <netinet/tcp_var.h> 213 #include <netinet/tcp_private.h> 214 #include <netinet/tcpip.h> 215 #include <netinet/tcp_congctl.h> 216 #include <netinet/tcp_debug.h> 217 218 #ifdef IPSEC 219 #include <netinet6/ipsec.h> 220 #include <netinet6/ipsec_private.h> 221 #include <netkey/key.h> 222 #endif /*IPSEC*/ 223 #ifdef INET6 224 #include "faith.h" 225 #if defined(NFAITH) && NFAITH > 0 226 #include <net/if_faith.h> 227 #endif 228 #endif /* IPSEC */ 229 230 #ifdef FAST_IPSEC 231 #include <netipsec/ipsec.h> 232 #include <netipsec/ipsec_var.h> 233 #include <netipsec/ipsec_private.h> 234 #include <netipsec/key.h> 235 #ifdef INET6 236 #include <netipsec/ipsec6.h> 237 #endif 238 #endif /* FAST_IPSEC*/ 239 240 #include <netinet/tcp_vtw.h> 241 242 int tcprexmtthresh = 3; 243 int tcp_log_refused; 244 245 int tcp_do_autorcvbuf = 1; 246 int tcp_autorcvbuf_inc = 16 * 1024; 247 int tcp_autorcvbuf_max = 256 * 1024; 248 int tcp_msl = (TCPTV_MSL / PR_SLOWHZ); 249 250 static int tcp_rst_ppslim_count = 0; 251 static struct timeval tcp_rst_ppslim_last; 252 static int tcp_ackdrop_ppslim_count = 0; 253 static struct timeval tcp_ackdrop_ppslim_last; 254 255 #define TCP_PAWS_IDLE (24U * 24 * 60 * 60 * PR_SLOWHZ) 256 257 /* for modulo comparisons of timestamps */ 258 #define TSTMP_LT(a,b) ((int)((a)-(b)) < 0) 259 #define TSTMP_GEQ(a,b) ((int)((a)-(b)) >= 0) 260 261 /* 262 * Neighbor Discovery, Neighbor Unreachability Detection Upper layer hint. 263 */ 264 #ifdef INET6 265 static inline void 266 nd6_hint(struct tcpcb *tp) 267 { 268 struct rtentry *rt; 269 270 if (tp != NULL && tp->t_in6pcb != NULL && tp->t_family == AF_INET6 && 271 (rt = rtcache_validate(&tp->t_in6pcb->in6p_route)) != NULL) 272 nd6_nud_hint(rt, NULL, 0); 273 } 274 #else 275 static inline void 276 nd6_hint(struct tcpcb *tp) 277 { 278 } 279 #endif 280 281 /* 282 * Compute ACK transmission behavior. Delay the ACK unless 283 * we have already delayed an ACK (must send an ACK every two segments). 284 * We also ACK immediately if we received a PUSH and the ACK-on-PUSH 285 * option is enabled. 286 */ 287 static void 288 tcp_setup_ack(struct tcpcb *tp, const struct tcphdr *th) 289 { 290 291 if (tp->t_flags & TF_DELACK || 292 (tcp_ack_on_push && th->th_flags & TH_PUSH)) 293 tp->t_flags |= TF_ACKNOW; 294 else 295 TCP_SET_DELACK(tp); 296 } 297 298 static void 299 icmp_check(struct tcpcb *tp, const struct tcphdr *th, int acked) 300 { 301 302 /* 303 * If we had a pending ICMP message that refers to data that have 304 * just been acknowledged, disregard the recorded ICMP message. 305 */ 306 if ((tp->t_flags & TF_PMTUD_PEND) && 307 SEQ_GT(th->th_ack, tp->t_pmtud_th_seq)) 308 tp->t_flags &= ~TF_PMTUD_PEND; 309 310 /* 311 * Keep track of the largest chunk of data 312 * acknowledged since last PMTU update 313 */ 314 if (tp->t_pmtud_mss_acked < acked) 315 tp->t_pmtud_mss_acked = acked; 316 } 317 318 /* 319 * Convert TCP protocol fields to host order for easier processing. 320 */ 321 static void 322 tcp_fields_to_host(struct tcphdr *th) 323 { 324 325 NTOHL(th->th_seq); 326 NTOHL(th->th_ack); 327 NTOHS(th->th_win); 328 NTOHS(th->th_urp); 329 } 330 331 /* 332 * ... and reverse the above. 333 */ 334 static void 335 tcp_fields_to_net(struct tcphdr *th) 336 { 337 338 HTONL(th->th_seq); 339 HTONL(th->th_ack); 340 HTONS(th->th_win); 341 HTONS(th->th_urp); 342 } 343 344 #ifdef TCP_CSUM_COUNTERS 345 #include <sys/device.h> 346 347 #if defined(INET) 348 extern struct evcnt tcp_hwcsum_ok; 349 extern struct evcnt tcp_hwcsum_bad; 350 extern struct evcnt tcp_hwcsum_data; 351 extern struct evcnt tcp_swcsum; 352 #endif /* defined(INET) */ 353 #if defined(INET6) 354 extern struct evcnt tcp6_hwcsum_ok; 355 extern struct evcnt tcp6_hwcsum_bad; 356 extern struct evcnt tcp6_hwcsum_data; 357 extern struct evcnt tcp6_swcsum; 358 #endif /* defined(INET6) */ 359 360 #define TCP_CSUM_COUNTER_INCR(ev) (ev)->ev_count++ 361 362 #else 363 364 #define TCP_CSUM_COUNTER_INCR(ev) /* nothing */ 365 366 #endif /* TCP_CSUM_COUNTERS */ 367 368 #ifdef TCP_REASS_COUNTERS 369 #include <sys/device.h> 370 371 extern struct evcnt tcp_reass_; 372 extern struct evcnt tcp_reass_empty; 373 extern struct evcnt tcp_reass_iteration[8]; 374 extern struct evcnt tcp_reass_prependfirst; 375 extern struct evcnt tcp_reass_prepend; 376 extern struct evcnt tcp_reass_insert; 377 extern struct evcnt tcp_reass_inserttail; 378 extern struct evcnt tcp_reass_append; 379 extern struct evcnt tcp_reass_appendtail; 380 extern struct evcnt tcp_reass_overlaptail; 381 extern struct evcnt tcp_reass_overlapfront; 382 extern struct evcnt tcp_reass_segdup; 383 extern struct evcnt tcp_reass_fragdup; 384 385 #define TCP_REASS_COUNTER_INCR(ev) (ev)->ev_count++ 386 387 #else 388 389 #define TCP_REASS_COUNTER_INCR(ev) /* nothing */ 390 391 #endif /* TCP_REASS_COUNTERS */ 392 393 static int tcp_reass(struct tcpcb *, const struct tcphdr *, struct mbuf *, 394 int *); 395 static int tcp_dooptions(struct tcpcb *, const u_char *, int, 396 struct tcphdr *, struct mbuf *, int, struct tcp_opt_info *); 397 398 #ifdef INET 399 static void tcp4_log_refused(const struct ip *, const struct tcphdr *); 400 #endif 401 #ifdef INET6 402 static void tcp6_log_refused(const struct ip6_hdr *, const struct tcphdr *); 403 #endif 404 405 #define TRAVERSE(x) while ((x)->m_next) (x) = (x)->m_next 406 407 #if defined(MBUFTRACE) 408 struct mowner tcp_reass_mowner = MOWNER_INIT("tcp", "reass"); 409 #endif /* defined(MBUFTRACE) */ 410 411 static struct pool tcpipqent_pool; 412 413 void 414 tcpipqent_init(void) 415 { 416 417 pool_init(&tcpipqent_pool, sizeof(struct ipqent), 0, 0, 0, "tcpipqepl", 418 NULL, IPL_VM); 419 } 420 421 struct ipqent * 422 tcpipqent_alloc(void) 423 { 424 struct ipqent *ipqe; 425 int s; 426 427 s = splvm(); 428 ipqe = pool_get(&tcpipqent_pool, PR_NOWAIT); 429 splx(s); 430 431 return ipqe; 432 } 433 434 void 435 tcpipqent_free(struct ipqent *ipqe) 436 { 437 int s; 438 439 s = splvm(); 440 pool_put(&tcpipqent_pool, ipqe); 441 splx(s); 442 } 443 444 static int 445 tcp_reass(struct tcpcb *tp, const struct tcphdr *th, struct mbuf *m, int *tlen) 446 { 447 struct ipqent *p, *q, *nq, *tiqe = NULL; 448 struct socket *so = NULL; 449 int pkt_flags; 450 tcp_seq pkt_seq; 451 unsigned pkt_len; 452 u_long rcvpartdupbyte = 0; 453 u_long rcvoobyte; 454 #ifdef TCP_REASS_COUNTERS 455 u_int count = 0; 456 #endif 457 uint64_t *tcps; 458 459 if (tp->t_inpcb) 460 so = tp->t_inpcb->inp_socket; 461 #ifdef INET6 462 else if (tp->t_in6pcb) 463 so = tp->t_in6pcb->in6p_socket; 464 #endif 465 466 TCP_REASS_LOCK_CHECK(tp); 467 468 /* 469 * Call with th==0 after become established to 470 * force pre-ESTABLISHED data up to user socket. 471 */ 472 if (th == 0) 473 goto present; 474 475 m_claimm(m, &tcp_reass_mowner); 476 477 rcvoobyte = *tlen; 478 /* 479 * Copy these to local variables because the tcpiphdr 480 * gets munged while we are collapsing mbufs. 481 */ 482 pkt_seq = th->th_seq; 483 pkt_len = *tlen; 484 pkt_flags = th->th_flags; 485 486 TCP_REASS_COUNTER_INCR(&tcp_reass_); 487 488 if ((p = TAILQ_LAST(&tp->segq, ipqehead)) != NULL) { 489 /* 490 * When we miss a packet, the vast majority of time we get 491 * packets that follow it in order. So optimize for that. 492 */ 493 if (pkt_seq == p->ipqe_seq + p->ipqe_len) { 494 p->ipqe_len += pkt_len; 495 p->ipqe_flags |= pkt_flags; 496 m_cat(p->ipre_mlast, m); 497 TRAVERSE(p->ipre_mlast); 498 m = NULL; 499 tiqe = p; 500 TAILQ_REMOVE(&tp->timeq, p, ipqe_timeq); 501 TCP_REASS_COUNTER_INCR(&tcp_reass_appendtail); 502 goto skip_replacement; 503 } 504 /* 505 * While we're here, if the pkt is completely beyond 506 * anything we have, just insert it at the tail. 507 */ 508 if (SEQ_GT(pkt_seq, p->ipqe_seq + p->ipqe_len)) { 509 TCP_REASS_COUNTER_INCR(&tcp_reass_inserttail); 510 goto insert_it; 511 } 512 } 513 514 q = TAILQ_FIRST(&tp->segq); 515 516 if (q != NULL) { 517 /* 518 * If this segment immediately precedes the first out-of-order 519 * block, simply slap the segment in front of it and (mostly) 520 * skip the complicated logic. 521 */ 522 if (pkt_seq + pkt_len == q->ipqe_seq) { 523 q->ipqe_seq = pkt_seq; 524 q->ipqe_len += pkt_len; 525 q->ipqe_flags |= pkt_flags; 526 m_cat(m, q->ipqe_m); 527 q->ipqe_m = m; 528 q->ipre_mlast = m; /* last mbuf may have changed */ 529 TRAVERSE(q->ipre_mlast); 530 tiqe = q; 531 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 532 TCP_REASS_COUNTER_INCR(&tcp_reass_prependfirst); 533 goto skip_replacement; 534 } 535 } else { 536 TCP_REASS_COUNTER_INCR(&tcp_reass_empty); 537 } 538 539 /* 540 * Find a segment which begins after this one does. 541 */ 542 for (p = NULL; q != NULL; q = nq) { 543 nq = TAILQ_NEXT(q, ipqe_q); 544 #ifdef TCP_REASS_COUNTERS 545 count++; 546 #endif 547 /* 548 * If the received segment is just right after this 549 * fragment, merge the two together and then check 550 * for further overlaps. 551 */ 552 if (q->ipqe_seq + q->ipqe_len == pkt_seq) { 553 #ifdef TCPREASS_DEBUG 554 printf("tcp_reass[%p]: concat %u:%u(%u) to %u:%u(%u)\n", 555 tp, pkt_seq, pkt_seq + pkt_len, pkt_len, 556 q->ipqe_seq, q->ipqe_seq + q->ipqe_len, q->ipqe_len); 557 #endif 558 pkt_len += q->ipqe_len; 559 pkt_flags |= q->ipqe_flags; 560 pkt_seq = q->ipqe_seq; 561 m_cat(q->ipre_mlast, m); 562 TRAVERSE(q->ipre_mlast); 563 m = q->ipqe_m; 564 TCP_REASS_COUNTER_INCR(&tcp_reass_append); 565 goto free_ipqe; 566 } 567 /* 568 * If the received segment is completely past this 569 * fragment, we need to go the next fragment. 570 */ 571 if (SEQ_LT(q->ipqe_seq + q->ipqe_len, pkt_seq)) { 572 p = q; 573 continue; 574 } 575 /* 576 * If the fragment is past the received segment, 577 * it (or any following) can't be concatenated. 578 */ 579 if (SEQ_GT(q->ipqe_seq, pkt_seq + pkt_len)) { 580 TCP_REASS_COUNTER_INCR(&tcp_reass_insert); 581 break; 582 } 583 584 /* 585 * We've received all the data in this segment before. 586 * mark it as a duplicate and return. 587 */ 588 if (SEQ_LEQ(q->ipqe_seq, pkt_seq) && 589 SEQ_GEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) { 590 tcps = TCP_STAT_GETREF(); 591 tcps[TCP_STAT_RCVDUPPACK]++; 592 tcps[TCP_STAT_RCVDUPBYTE] += pkt_len; 593 TCP_STAT_PUTREF(); 594 tcp_new_dsack(tp, pkt_seq, pkt_len); 595 m_freem(m); 596 if (tiqe != NULL) { 597 tcpipqent_free(tiqe); 598 } 599 TCP_REASS_COUNTER_INCR(&tcp_reass_segdup); 600 goto out; 601 } 602 /* 603 * Received segment completely overlaps this fragment 604 * so we drop the fragment (this keeps the temporal 605 * ordering of segments correct). 606 */ 607 if (SEQ_GEQ(q->ipqe_seq, pkt_seq) && 608 SEQ_LEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) { 609 rcvpartdupbyte += q->ipqe_len; 610 m_freem(q->ipqe_m); 611 TCP_REASS_COUNTER_INCR(&tcp_reass_fragdup); 612 goto free_ipqe; 613 } 614 /* 615 * RX'ed segment extends past the end of the 616 * fragment. Drop the overlapping bytes. Then 617 * merge the fragment and segment then treat as 618 * a longer received packet. 619 */ 620 if (SEQ_LT(q->ipqe_seq, pkt_seq) && 621 SEQ_GT(q->ipqe_seq + q->ipqe_len, pkt_seq)) { 622 int overlap = q->ipqe_seq + q->ipqe_len - pkt_seq; 623 #ifdef TCPREASS_DEBUG 624 printf("tcp_reass[%p]: trim starting %d bytes of %u:%u(%u)\n", 625 tp, overlap, 626 pkt_seq, pkt_seq + pkt_len, pkt_len); 627 #endif 628 m_adj(m, overlap); 629 rcvpartdupbyte += overlap; 630 m_cat(q->ipre_mlast, m); 631 TRAVERSE(q->ipre_mlast); 632 m = q->ipqe_m; 633 pkt_seq = q->ipqe_seq; 634 pkt_len += q->ipqe_len - overlap; 635 rcvoobyte -= overlap; 636 TCP_REASS_COUNTER_INCR(&tcp_reass_overlaptail); 637 goto free_ipqe; 638 } 639 /* 640 * RX'ed segment extends past the front of the 641 * fragment. Drop the overlapping bytes on the 642 * received packet. The packet will then be 643 * contatentated with this fragment a bit later. 644 */ 645 if (SEQ_GT(q->ipqe_seq, pkt_seq) && 646 SEQ_LT(q->ipqe_seq, pkt_seq + pkt_len)) { 647 int overlap = pkt_seq + pkt_len - q->ipqe_seq; 648 #ifdef TCPREASS_DEBUG 649 printf("tcp_reass[%p]: trim trailing %d bytes of %u:%u(%u)\n", 650 tp, overlap, 651 pkt_seq, pkt_seq + pkt_len, pkt_len); 652 #endif 653 m_adj(m, -overlap); 654 pkt_len -= overlap; 655 rcvpartdupbyte += overlap; 656 TCP_REASS_COUNTER_INCR(&tcp_reass_overlapfront); 657 rcvoobyte -= overlap; 658 } 659 /* 660 * If the received segment immediates precedes this 661 * fragment then tack the fragment onto this segment 662 * and reinsert the data. 663 */ 664 if (q->ipqe_seq == pkt_seq + pkt_len) { 665 #ifdef TCPREASS_DEBUG 666 printf("tcp_reass[%p]: append %u:%u(%u) to %u:%u(%u)\n", 667 tp, q->ipqe_seq, q->ipqe_seq + q->ipqe_len, q->ipqe_len, 668 pkt_seq, pkt_seq + pkt_len, pkt_len); 669 #endif 670 pkt_len += q->ipqe_len; 671 pkt_flags |= q->ipqe_flags; 672 m_cat(m, q->ipqe_m); 673 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 674 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 675 tp->t_segqlen--; 676 KASSERT(tp->t_segqlen >= 0); 677 KASSERT(tp->t_segqlen != 0 || 678 (TAILQ_EMPTY(&tp->segq) && 679 TAILQ_EMPTY(&tp->timeq))); 680 if (tiqe == NULL) { 681 tiqe = q; 682 } else { 683 tcpipqent_free(q); 684 } 685 TCP_REASS_COUNTER_INCR(&tcp_reass_prepend); 686 break; 687 } 688 /* 689 * If the fragment is before the segment, remember it. 690 * When this loop is terminated, p will contain the 691 * pointer to fragment that is right before the received 692 * segment. 693 */ 694 if (SEQ_LEQ(q->ipqe_seq, pkt_seq)) 695 p = q; 696 697 continue; 698 699 /* 700 * This is a common operation. It also will allow 701 * to save doing a malloc/free in most instances. 702 */ 703 free_ipqe: 704 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 705 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 706 tp->t_segqlen--; 707 KASSERT(tp->t_segqlen >= 0); 708 KASSERT(tp->t_segqlen != 0 || 709 (TAILQ_EMPTY(&tp->segq) && TAILQ_EMPTY(&tp->timeq))); 710 if (tiqe == NULL) { 711 tiqe = q; 712 } else { 713 tcpipqent_free(q); 714 } 715 } 716 717 #ifdef TCP_REASS_COUNTERS 718 if (count > 7) 719 TCP_REASS_COUNTER_INCR(&tcp_reass_iteration[0]); 720 else if (count > 0) 721 TCP_REASS_COUNTER_INCR(&tcp_reass_iteration[count]); 722 #endif 723 724 insert_it: 725 726 /* 727 * Allocate a new queue entry since the received segment did not 728 * collapse onto any other out-of-order block; thus we are allocating 729 * a new block. If it had collapsed, tiqe would not be NULL and 730 * we would be reusing it. 731 * XXX If we can't, just drop the packet. XXX 732 */ 733 if (tiqe == NULL) { 734 tiqe = tcpipqent_alloc(); 735 if (tiqe == NULL) { 736 TCP_STATINC(TCP_STAT_RCVMEMDROP); 737 m_freem(m); 738 goto out; 739 } 740 } 741 742 /* 743 * Update the counters. 744 */ 745 tcps = TCP_STAT_GETREF(); 746 tcps[TCP_STAT_RCVOOPACK]++; 747 tcps[TCP_STAT_RCVOOBYTE] += rcvoobyte; 748 if (rcvpartdupbyte) { 749 tcps[TCP_STAT_RCVPARTDUPPACK]++; 750 tcps[TCP_STAT_RCVPARTDUPBYTE] += rcvpartdupbyte; 751 } 752 TCP_STAT_PUTREF(); 753 754 /* 755 * Insert the new fragment queue entry into both queues. 756 */ 757 tiqe->ipqe_m = m; 758 tiqe->ipre_mlast = m; 759 tiqe->ipqe_seq = pkt_seq; 760 tiqe->ipqe_len = pkt_len; 761 tiqe->ipqe_flags = pkt_flags; 762 if (p == NULL) { 763 TAILQ_INSERT_HEAD(&tp->segq, tiqe, ipqe_q); 764 #ifdef TCPREASS_DEBUG 765 if (tiqe->ipqe_seq != tp->rcv_nxt) 766 printf("tcp_reass[%p]: insert %u:%u(%u) at front\n", 767 tp, pkt_seq, pkt_seq + pkt_len, pkt_len); 768 #endif 769 } else { 770 TAILQ_INSERT_AFTER(&tp->segq, p, tiqe, ipqe_q); 771 #ifdef TCPREASS_DEBUG 772 printf("tcp_reass[%p]: insert %u:%u(%u) after %u:%u(%u)\n", 773 tp, pkt_seq, pkt_seq + pkt_len, pkt_len, 774 p->ipqe_seq, p->ipqe_seq + p->ipqe_len, p->ipqe_len); 775 #endif 776 } 777 tp->t_segqlen++; 778 779 skip_replacement: 780 781 TAILQ_INSERT_HEAD(&tp->timeq, tiqe, ipqe_timeq); 782 783 present: 784 /* 785 * Present data to user, advancing rcv_nxt through 786 * completed sequence space. 787 */ 788 if (TCPS_HAVEESTABLISHED(tp->t_state) == 0) 789 goto out; 790 q = TAILQ_FIRST(&tp->segq); 791 if (q == NULL || q->ipqe_seq != tp->rcv_nxt) 792 goto out; 793 if (tp->t_state == TCPS_SYN_RECEIVED && q->ipqe_len) 794 goto out; 795 796 tp->rcv_nxt += q->ipqe_len; 797 pkt_flags = q->ipqe_flags & TH_FIN; 798 nd6_hint(tp); 799 800 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 801 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 802 tp->t_segqlen--; 803 KASSERT(tp->t_segqlen >= 0); 804 KASSERT(tp->t_segqlen != 0 || 805 (TAILQ_EMPTY(&tp->segq) && TAILQ_EMPTY(&tp->timeq))); 806 if (so->so_state & SS_CANTRCVMORE) 807 m_freem(q->ipqe_m); 808 else 809 sbappendstream(&so->so_rcv, q->ipqe_m); 810 tcpipqent_free(q); 811 TCP_REASS_UNLOCK(tp); 812 sorwakeup(so); 813 return (pkt_flags); 814 out: 815 TCP_REASS_UNLOCK(tp); 816 return (0); 817 } 818 819 #ifdef INET6 820 int 821 tcp6_input(struct mbuf **mp, int *offp, int proto) 822 { 823 struct mbuf *m = *mp; 824 825 /* 826 * draft-itojun-ipv6-tcp-to-anycast 827 * better place to put this in? 828 */ 829 if (m->m_flags & M_ANYCAST6) { 830 struct ip6_hdr *ip6; 831 if (m->m_len < sizeof(struct ip6_hdr)) { 832 if ((m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) { 833 TCP_STATINC(TCP_STAT_RCVSHORT); 834 return IPPROTO_DONE; 835 } 836 } 837 ip6 = mtod(m, struct ip6_hdr *); 838 icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR, 839 (char *)&ip6->ip6_dst - (char *)ip6); 840 return IPPROTO_DONE; 841 } 842 843 tcp_input(m, *offp, proto); 844 return IPPROTO_DONE; 845 } 846 #endif 847 848 #ifdef INET 849 static void 850 tcp4_log_refused(const struct ip *ip, const struct tcphdr *th) 851 { 852 char src[4*sizeof "123"]; 853 char dst[4*sizeof "123"]; 854 855 if (ip) { 856 strlcpy(src, inet_ntoa(ip->ip_src), sizeof(src)); 857 strlcpy(dst, inet_ntoa(ip->ip_dst), sizeof(dst)); 858 } 859 else { 860 strlcpy(src, "(unknown)", sizeof(src)); 861 strlcpy(dst, "(unknown)", sizeof(dst)); 862 } 863 log(LOG_INFO, 864 "Connection attempt to TCP %s:%d from %s:%d\n", 865 dst, ntohs(th->th_dport), 866 src, ntohs(th->th_sport)); 867 } 868 #endif 869 870 #ifdef INET6 871 static void 872 tcp6_log_refused(const struct ip6_hdr *ip6, const struct tcphdr *th) 873 { 874 char src[INET6_ADDRSTRLEN]; 875 char dst[INET6_ADDRSTRLEN]; 876 877 if (ip6) { 878 strlcpy(src, ip6_sprintf(&ip6->ip6_src), sizeof(src)); 879 strlcpy(dst, ip6_sprintf(&ip6->ip6_dst), sizeof(dst)); 880 } 881 else { 882 strlcpy(src, "(unknown v6)", sizeof(src)); 883 strlcpy(dst, "(unknown v6)", sizeof(dst)); 884 } 885 log(LOG_INFO, 886 "Connection attempt to TCP [%s]:%d from [%s]:%d\n", 887 dst, ntohs(th->th_dport), 888 src, ntohs(th->th_sport)); 889 } 890 #endif 891 892 /* 893 * Checksum extended TCP header and data. 894 */ 895 int 896 tcp_input_checksum(int af, struct mbuf *m, const struct tcphdr *th, 897 int toff, int off, int tlen) 898 { 899 900 /* 901 * XXX it's better to record and check if this mbuf is 902 * already checked. 903 */ 904 905 switch (af) { 906 #ifdef INET 907 case AF_INET: 908 switch (m->m_pkthdr.csum_flags & 909 ((m->m_pkthdr.rcvif->if_csum_flags_rx & M_CSUM_TCPv4) | 910 M_CSUM_TCP_UDP_BAD | M_CSUM_DATA)) { 911 case M_CSUM_TCPv4|M_CSUM_TCP_UDP_BAD: 912 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_bad); 913 goto badcsum; 914 915 case M_CSUM_TCPv4|M_CSUM_DATA: { 916 u_int32_t hw_csum = m->m_pkthdr.csum_data; 917 918 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_data); 919 if (m->m_pkthdr.csum_flags & M_CSUM_NO_PSEUDOHDR) { 920 const struct ip *ip = 921 mtod(m, const struct ip *); 922 923 hw_csum = in_cksum_phdr(ip->ip_src.s_addr, 924 ip->ip_dst.s_addr, 925 htons(hw_csum + tlen + off + IPPROTO_TCP)); 926 } 927 if ((hw_csum ^ 0xffff) != 0) 928 goto badcsum; 929 break; 930 } 931 932 case M_CSUM_TCPv4: 933 /* Checksum was okay. */ 934 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_ok); 935 break; 936 937 default: 938 /* 939 * Must compute it ourselves. Maybe skip checksum 940 * on loopback interfaces. 941 */ 942 if (__predict_true(!(m->m_pkthdr.rcvif->if_flags & 943 IFF_LOOPBACK) || 944 tcp_do_loopback_cksum)) { 945 TCP_CSUM_COUNTER_INCR(&tcp_swcsum); 946 if (in4_cksum(m, IPPROTO_TCP, toff, 947 tlen + off) != 0) 948 goto badcsum; 949 } 950 break; 951 } 952 break; 953 #endif /* INET4 */ 954 955 #ifdef INET6 956 case AF_INET6: 957 switch (m->m_pkthdr.csum_flags & 958 ((m->m_pkthdr.rcvif->if_csum_flags_rx & M_CSUM_TCPv6) | 959 M_CSUM_TCP_UDP_BAD | M_CSUM_DATA)) { 960 case M_CSUM_TCPv6|M_CSUM_TCP_UDP_BAD: 961 TCP_CSUM_COUNTER_INCR(&tcp6_hwcsum_bad); 962 goto badcsum; 963 964 #if 0 /* notyet */ 965 case M_CSUM_TCPv6|M_CSUM_DATA: 966 #endif 967 968 case M_CSUM_TCPv6: 969 /* Checksum was okay. */ 970 TCP_CSUM_COUNTER_INCR(&tcp6_hwcsum_ok); 971 break; 972 973 default: 974 /* 975 * Must compute it ourselves. Maybe skip checksum 976 * on loopback interfaces. 977 */ 978 if (__predict_true((m->m_flags & M_LOOP) == 0 || 979 tcp_do_loopback_cksum)) { 980 TCP_CSUM_COUNTER_INCR(&tcp6_swcsum); 981 if (in6_cksum(m, IPPROTO_TCP, toff, 982 tlen + off) != 0) 983 goto badcsum; 984 } 985 } 986 break; 987 #endif /* INET6 */ 988 } 989 990 return 0; 991 992 badcsum: 993 TCP_STATINC(TCP_STAT_RCVBADSUM); 994 return -1; 995 } 996 997 /* When a packet arrives addressed to a vestigial tcpbp, we 998 * nevertheless have to respond to it per the spec. 999 */ 1000 static void tcp_vtw_input(struct tcphdr *th, vestigial_inpcb_t *vp, 1001 struct mbuf *m, int tlen, int multicast) 1002 { 1003 int tiflags; 1004 int todrop, dupseg; 1005 uint32_t t_flags = 0; 1006 uint64_t *tcps; 1007 1008 tiflags = th->th_flags; 1009 todrop = vp->rcv_nxt - th->th_seq; 1010 dupseg = false; 1011 1012 if (todrop > 0) { 1013 if (tiflags & TH_SYN) { 1014 tiflags &= ~TH_SYN; 1015 ++th->th_seq; 1016 if (th->th_urp > 1) 1017 --th->th_urp; 1018 else { 1019 tiflags &= ~TH_URG; 1020 th->th_urp = 0; 1021 } 1022 --todrop; 1023 } 1024 if (todrop > tlen || 1025 (todrop == tlen && (tiflags & TH_FIN) == 0)) { 1026 /* 1027 * Any valid FIN or RST must be to the left of the 1028 * window. At this point the FIN or RST must be a 1029 * duplicate or out of sequence; drop it. 1030 */ 1031 if (tiflags & TH_RST) 1032 goto drop; 1033 tiflags &= ~(TH_FIN|TH_RST); 1034 /* 1035 * Send an ACK to resynchronize and drop any data. 1036 * But keep on processing for RST or ACK. 1037 */ 1038 t_flags |= TF_ACKNOW; 1039 todrop = tlen; 1040 dupseg = true; 1041 tcps = TCP_STAT_GETREF(); 1042 tcps[TCP_STAT_RCVDUPPACK] += 1; 1043 tcps[TCP_STAT_RCVDUPBYTE] += todrop; 1044 TCP_STAT_PUTREF(); 1045 } else if ((tiflags & TH_RST) 1046 && th->th_seq != vp->rcv_nxt) { 1047 /* 1048 * Test for reset before adjusting the sequence 1049 * number for overlapping data. 1050 */ 1051 goto dropafterack_ratelim; 1052 } else { 1053 tcps = TCP_STAT_GETREF(); 1054 tcps[TCP_STAT_RCVPARTDUPPACK] += 1; 1055 tcps[TCP_STAT_RCVPARTDUPBYTE] += todrop; 1056 TCP_STAT_PUTREF(); 1057 } 1058 1059 // tcp_new_dsack(tp, th->th_seq, todrop); 1060 // hdroptlen += todrop; /*drop from head afterwards*/ 1061 1062 th->th_seq += todrop; 1063 tlen -= todrop; 1064 1065 if (th->th_urp > todrop) 1066 th->th_urp -= todrop; 1067 else { 1068 tiflags &= ~TH_URG; 1069 th->th_urp = 0; 1070 } 1071 } 1072 1073 /* 1074 * If new data are received on a connection after the 1075 * user processes are gone, then RST the other end. 1076 */ 1077 if (tlen) { 1078 TCP_STATINC(TCP_STAT_RCVAFTERCLOSE); 1079 goto dropwithreset; 1080 } 1081 1082 /* 1083 * If segment ends after window, drop trailing data 1084 * (and PUSH and FIN); if nothing left, just ACK. 1085 */ 1086 todrop = (th->th_seq + tlen) - (vp->rcv_nxt+vp->rcv_wnd); 1087 1088 if (todrop > 0) { 1089 TCP_STATINC(TCP_STAT_RCVPACKAFTERWIN); 1090 if (todrop >= tlen) { 1091 /* 1092 * The segment actually starts after the window. 1093 * th->th_seq + tlen - vp->rcv_nxt - vp->rcv_wnd >= tlen 1094 * th->th_seq - vp->rcv_nxt - vp->rcv_wnd >= 0 1095 * th->th_seq >= vp->rcv_nxt + vp->rcv_wnd 1096 */ 1097 TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, tlen); 1098 /* 1099 * If a new connection request is received 1100 * while in TIME_WAIT, drop the old connection 1101 * and start over if the sequence numbers 1102 * are above the previous ones. 1103 */ 1104 if ((tiflags & TH_SYN) 1105 && SEQ_GT(th->th_seq, vp->rcv_nxt)) { 1106 /* We only support this in the !NOFDREF case, which 1107 * is to say: not here. 1108 */ 1109 goto dropwithreset;; 1110 } 1111 /* 1112 * If window is closed can only take segments at 1113 * window edge, and have to drop data and PUSH from 1114 * incoming segments. Continue processing, but 1115 * remember to ack. Otherwise, drop segment 1116 * and (if not RST) ack. 1117 */ 1118 if (vp->rcv_wnd == 0 && th->th_seq == vp->rcv_nxt) { 1119 t_flags |= TF_ACKNOW; 1120 TCP_STATINC(TCP_STAT_RCVWINPROBE); 1121 } else 1122 goto dropafterack; 1123 } else 1124 TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, todrop); 1125 m_adj(m, -todrop); 1126 tlen -= todrop; 1127 tiflags &= ~(TH_PUSH|TH_FIN); 1128 } 1129 1130 if (tiflags & TH_RST) { 1131 if (th->th_seq != vp->rcv_nxt) 1132 goto dropafterack_ratelim; 1133 1134 vtw_del(vp->ctl, vp->vtw); 1135 goto drop; 1136 } 1137 1138 /* 1139 * If the ACK bit is off we drop the segment and return. 1140 */ 1141 if ((tiflags & TH_ACK) == 0) { 1142 if (t_flags & TF_ACKNOW) 1143 goto dropafterack; 1144 else 1145 goto drop; 1146 } 1147 1148 /* 1149 * In TIME_WAIT state the only thing that should arrive 1150 * is a retransmission of the remote FIN. Acknowledge 1151 * it and restart the finack timer. 1152 */ 1153 vtw_restart(vp); 1154 goto dropafterack; 1155 1156 dropafterack: 1157 /* 1158 * Generate an ACK dropping incoming segment if it occupies 1159 * sequence space, where the ACK reflects our state. 1160 */ 1161 if (tiflags & TH_RST) 1162 goto drop; 1163 goto dropafterack2; 1164 1165 dropafterack_ratelim: 1166 /* 1167 * We may want to rate-limit ACKs against SYN/RST attack. 1168 */ 1169 if (ppsratecheck(&tcp_ackdrop_ppslim_last, &tcp_ackdrop_ppslim_count, 1170 tcp_ackdrop_ppslim) == 0) { 1171 /* XXX stat */ 1172 goto drop; 1173 } 1174 /* ...fall into dropafterack2... */ 1175 1176 dropafterack2: 1177 (void)tcp_respond(0, m, m, th, th->th_seq + tlen, th->th_ack, 1178 TH_ACK); 1179 return; 1180 1181 dropwithreset: 1182 /* 1183 * Generate a RST, dropping incoming segment. 1184 * Make ACK acceptable to originator of segment. 1185 */ 1186 if (tiflags & TH_RST) 1187 goto drop; 1188 1189 if (tiflags & TH_ACK) 1190 tcp_respond(0, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 1191 else { 1192 if (tiflags & TH_SYN) 1193 ++tlen; 1194 (void)tcp_respond(0, m, m, th, th->th_seq + tlen, (tcp_seq)0, 1195 TH_RST|TH_ACK); 1196 } 1197 return; 1198 drop: 1199 m_freem(m); 1200 } 1201 1202 /* 1203 * TCP input routine, follows pages 65-76 of RFC 793 very closely. 1204 */ 1205 void 1206 tcp_input(struct mbuf *m, ...) 1207 { 1208 struct tcphdr *th; 1209 struct ip *ip; 1210 struct inpcb *inp; 1211 #ifdef INET6 1212 struct ip6_hdr *ip6; 1213 struct in6pcb *in6p; 1214 #endif 1215 u_int8_t *optp = NULL; 1216 int optlen = 0; 1217 int len, tlen, toff, hdroptlen = 0; 1218 struct tcpcb *tp = 0; 1219 int tiflags; 1220 struct socket *so = NULL; 1221 int todrop, acked, ourfinisacked, needoutput = 0; 1222 bool dupseg; 1223 #ifdef TCP_DEBUG 1224 short ostate = 0; 1225 #endif 1226 u_long tiwin; 1227 struct tcp_opt_info opti; 1228 int off, iphlen; 1229 va_list ap; 1230 int af; /* af on the wire */ 1231 struct mbuf *tcp_saveti = NULL; 1232 uint32_t ts_rtt; 1233 uint8_t iptos; 1234 uint64_t *tcps; 1235 vestigial_inpcb_t vestige; 1236 1237 vestige.valid = 0; 1238 1239 MCLAIM(m, &tcp_rx_mowner); 1240 va_start(ap, m); 1241 toff = va_arg(ap, int); 1242 (void)va_arg(ap, int); /* ignore value, advance ap */ 1243 va_end(ap); 1244 1245 TCP_STATINC(TCP_STAT_RCVTOTAL); 1246 1247 memset(&opti, 0, sizeof(opti)); 1248 opti.ts_present = 0; 1249 opti.maxseg = 0; 1250 1251 /* 1252 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN. 1253 * 1254 * TCP is, by definition, unicast, so we reject all 1255 * multicast outright. 1256 * 1257 * Note, there are additional src/dst address checks in 1258 * the AF-specific code below. 1259 */ 1260 if (m->m_flags & (M_BCAST|M_MCAST)) { 1261 /* XXX stat */ 1262 goto drop; 1263 } 1264 #ifdef INET6 1265 if (m->m_flags & M_ANYCAST6) { 1266 /* XXX stat */ 1267 goto drop; 1268 } 1269 #endif 1270 1271 /* 1272 * Get IP and TCP header. 1273 * Note: IP leaves IP header in first mbuf. 1274 */ 1275 ip = mtod(m, struct ip *); 1276 switch (ip->ip_v) { 1277 #ifdef INET 1278 case 4: 1279 #ifdef INET6 1280 ip6 = NULL; 1281 #endif 1282 af = AF_INET; 1283 iphlen = sizeof(struct ip); 1284 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, 1285 sizeof(struct tcphdr)); 1286 if (th == NULL) { 1287 TCP_STATINC(TCP_STAT_RCVSHORT); 1288 return; 1289 } 1290 /* We do the checksum after PCB lookup... */ 1291 len = ntohs(ip->ip_len); 1292 tlen = len - toff; 1293 iptos = ip->ip_tos; 1294 break; 1295 #endif 1296 #ifdef INET6 1297 case 6: 1298 ip = NULL; 1299 iphlen = sizeof(struct ip6_hdr); 1300 af = AF_INET6; 1301 ip6 = mtod(m, struct ip6_hdr *); 1302 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, 1303 sizeof(struct tcphdr)); 1304 if (th == NULL) { 1305 TCP_STATINC(TCP_STAT_RCVSHORT); 1306 return; 1307 } 1308 1309 /* Be proactive about malicious use of IPv4 mapped address */ 1310 if (IN6_IS_ADDR_V4MAPPED(&ip6->ip6_src) || 1311 IN6_IS_ADDR_V4MAPPED(&ip6->ip6_dst)) { 1312 /* XXX stat */ 1313 goto drop; 1314 } 1315 1316 /* 1317 * Be proactive about unspecified IPv6 address in source. 1318 * As we use all-zero to indicate unbounded/unconnected pcb, 1319 * unspecified IPv6 address can be used to confuse us. 1320 * 1321 * Note that packets with unspecified IPv6 destination is 1322 * already dropped in ip6_input. 1323 */ 1324 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 1325 /* XXX stat */ 1326 goto drop; 1327 } 1328 1329 /* 1330 * Make sure destination address is not multicast. 1331 * Source address checked in ip6_input(). 1332 */ 1333 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) { 1334 /* XXX stat */ 1335 goto drop; 1336 } 1337 1338 /* We do the checksum after PCB lookup... */ 1339 len = m->m_pkthdr.len; 1340 tlen = len - toff; 1341 iptos = (ntohl(ip6->ip6_flow) >> 20) & 0xff; 1342 break; 1343 #endif 1344 default: 1345 m_freem(m); 1346 return; 1347 } 1348 1349 KASSERT(TCP_HDR_ALIGNED_P(th)); 1350 1351 /* 1352 * Check that TCP offset makes sense, 1353 * pull out TCP options and adjust length. XXX 1354 */ 1355 off = th->th_off << 2; 1356 if (off < sizeof (struct tcphdr) || off > tlen) { 1357 TCP_STATINC(TCP_STAT_RCVBADOFF); 1358 goto drop; 1359 } 1360 tlen -= off; 1361 1362 /* 1363 * tcp_input() has been modified to use tlen to mean the TCP data 1364 * length throughout the function. Other functions can use 1365 * m->m_pkthdr.len as the basis for calculating the TCP data length. 1366 * rja 1367 */ 1368 1369 if (off > sizeof (struct tcphdr)) { 1370 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, off); 1371 if (th == NULL) { 1372 TCP_STATINC(TCP_STAT_RCVSHORT); 1373 return; 1374 } 1375 /* 1376 * NOTE: ip/ip6 will not be affected by m_pulldown() 1377 * (as they're before toff) and we don't need to update those. 1378 */ 1379 KASSERT(TCP_HDR_ALIGNED_P(th)); 1380 optlen = off - sizeof (struct tcphdr); 1381 optp = ((u_int8_t *)th) + sizeof(struct tcphdr); 1382 /* 1383 * Do quick retrieval of timestamp options ("options 1384 * prediction?"). If timestamp is the only option and it's 1385 * formatted as recommended in RFC 1323 appendix A, we 1386 * quickly get the values now and not bother calling 1387 * tcp_dooptions(), etc. 1388 */ 1389 if ((optlen == TCPOLEN_TSTAMP_APPA || 1390 (optlen > TCPOLEN_TSTAMP_APPA && 1391 optp[TCPOLEN_TSTAMP_APPA] == TCPOPT_EOL)) && 1392 *(u_int32_t *)optp == htonl(TCPOPT_TSTAMP_HDR) && 1393 (th->th_flags & TH_SYN) == 0) { 1394 opti.ts_present = 1; 1395 opti.ts_val = ntohl(*(u_int32_t *)(optp + 4)); 1396 opti.ts_ecr = ntohl(*(u_int32_t *)(optp + 8)); 1397 optp = NULL; /* we've parsed the options */ 1398 } 1399 } 1400 tiflags = th->th_flags; 1401 1402 /* 1403 * Locate pcb for segment. 1404 */ 1405 findpcb: 1406 inp = NULL; 1407 #ifdef INET6 1408 in6p = NULL; 1409 #endif 1410 switch (af) { 1411 #ifdef INET 1412 case AF_INET: 1413 inp = in_pcblookup_connect(&tcbtable, ip->ip_src, th->th_sport, 1414 ip->ip_dst, th->th_dport, 1415 &vestige); 1416 if (inp == 0 && !vestige.valid) { 1417 TCP_STATINC(TCP_STAT_PCBHASHMISS); 1418 inp = in_pcblookup_bind(&tcbtable, ip->ip_dst, th->th_dport); 1419 } 1420 #ifdef INET6 1421 if (inp == 0 && !vestige.valid) { 1422 struct in6_addr s, d; 1423 1424 /* mapped addr case */ 1425 memset(&s, 0, sizeof(s)); 1426 s.s6_addr16[5] = htons(0xffff); 1427 bcopy(&ip->ip_src, &s.s6_addr32[3], sizeof(ip->ip_src)); 1428 memset(&d, 0, sizeof(d)); 1429 d.s6_addr16[5] = htons(0xffff); 1430 bcopy(&ip->ip_dst, &d.s6_addr32[3], sizeof(ip->ip_dst)); 1431 in6p = in6_pcblookup_connect(&tcbtable, &s, 1432 th->th_sport, &d, th->th_dport, 1433 0, &vestige); 1434 if (in6p == 0 && !vestige.valid) { 1435 TCP_STATINC(TCP_STAT_PCBHASHMISS); 1436 in6p = in6_pcblookup_bind(&tcbtable, &d, 1437 th->th_dport, 0); 1438 } 1439 } 1440 #endif 1441 #ifndef INET6 1442 if (inp == 0 && !vestige.valid) 1443 #else 1444 if (inp == 0 && in6p == 0 && !vestige.valid) 1445 #endif 1446 { 1447 TCP_STATINC(TCP_STAT_NOPORT); 1448 if (tcp_log_refused && 1449 (tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) { 1450 tcp4_log_refused(ip, th); 1451 } 1452 tcp_fields_to_host(th); 1453 goto dropwithreset_ratelim; 1454 } 1455 #if defined(IPSEC) || defined(FAST_IPSEC) 1456 if (inp && (inp->inp_socket->so_options & SO_ACCEPTCONN) == 0 && 1457 ipsec4_in_reject(m, inp)) { 1458 IPSEC_STATINC(IPSEC_STAT_IN_POLVIO); 1459 goto drop; 1460 } 1461 #ifdef INET6 1462 else if (in6p && 1463 (in6p->in6p_socket->so_options & SO_ACCEPTCONN) == 0 && 1464 ipsec6_in_reject_so(m, in6p->in6p_socket)) { 1465 IPSEC_STATINC(IPSEC_STAT_IN_POLVIO); 1466 goto drop; 1467 } 1468 #endif 1469 #endif /*IPSEC*/ 1470 break; 1471 #endif /*INET*/ 1472 #ifdef INET6 1473 case AF_INET6: 1474 { 1475 int faith; 1476 1477 #if defined(NFAITH) && NFAITH > 0 1478 faith = faithprefix(&ip6->ip6_dst); 1479 #else 1480 faith = 0; 1481 #endif 1482 in6p = in6_pcblookup_connect(&tcbtable, &ip6->ip6_src, 1483 th->th_sport, &ip6->ip6_dst, th->th_dport, faith, &vestige); 1484 if (!in6p && !vestige.valid) { 1485 TCP_STATINC(TCP_STAT_PCBHASHMISS); 1486 in6p = in6_pcblookup_bind(&tcbtable, &ip6->ip6_dst, 1487 th->th_dport, faith); 1488 } 1489 if (!in6p && !vestige.valid) { 1490 TCP_STATINC(TCP_STAT_NOPORT); 1491 if (tcp_log_refused && 1492 (tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) { 1493 tcp6_log_refused(ip6, th); 1494 } 1495 tcp_fields_to_host(th); 1496 goto dropwithreset_ratelim; 1497 } 1498 #if defined(IPSEC) || defined(FAST_IPSEC) 1499 if (in6p 1500 && (in6p->in6p_socket->so_options & SO_ACCEPTCONN) == 0 1501 && ipsec6_in_reject(m, in6p)) { 1502 IPSEC6_STATINC(IPSEC_STAT_IN_POLVIO); 1503 goto drop; 1504 } 1505 #endif /*IPSEC*/ 1506 break; 1507 } 1508 #endif 1509 } 1510 1511 /* 1512 * If the state is CLOSED (i.e., TCB does not exist) then 1513 * all data in the incoming segment is discarded. 1514 * If the TCB exists but is in CLOSED state, it is embryonic, 1515 * but should either do a listen or a connect soon. 1516 */ 1517 tp = NULL; 1518 so = NULL; 1519 if (inp) { 1520 /* Check the minimum TTL for socket. */ 1521 if (ip->ip_ttl < inp->inp_ip_minttl) 1522 goto drop; 1523 1524 tp = intotcpcb(inp); 1525 so = inp->inp_socket; 1526 } 1527 #ifdef INET6 1528 else if (in6p) { 1529 tp = in6totcpcb(in6p); 1530 so = in6p->in6p_socket; 1531 } 1532 #endif 1533 else if (vestige.valid) { 1534 int mc = 0; 1535 1536 /* We do not support the resurrection of vtw tcpcps. 1537 */ 1538 if (tcp_input_checksum(af, m, th, toff, off, tlen)) 1539 goto badcsum; 1540 1541 switch (af) { 1542 #ifdef INET6 1543 case AF_INET6: 1544 mc = IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst); 1545 break; 1546 #endif 1547 1548 case AF_INET: 1549 mc = (IN_MULTICAST(ip->ip_dst.s_addr) 1550 || in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)); 1551 break; 1552 } 1553 1554 tcp_fields_to_host(th); 1555 tcp_vtw_input(th, &vestige, m, tlen, mc); 1556 m = 0; 1557 goto drop; 1558 } 1559 1560 if (tp == 0) { 1561 tcp_fields_to_host(th); 1562 goto dropwithreset_ratelim; 1563 } 1564 if (tp->t_state == TCPS_CLOSED) 1565 goto drop; 1566 1567 KASSERT(so->so_lock == softnet_lock); 1568 KASSERT(solocked(so)); 1569 1570 /* 1571 * Checksum extended TCP header and data. 1572 */ 1573 if (tcp_input_checksum(af, m, th, toff, off, tlen)) 1574 goto badcsum; 1575 1576 tcp_fields_to_host(th); 1577 1578 /* Unscale the window into a 32-bit value. */ 1579 if ((tiflags & TH_SYN) == 0) 1580 tiwin = th->th_win << tp->snd_scale; 1581 else 1582 tiwin = th->th_win; 1583 1584 #ifdef INET6 1585 /* save packet options if user wanted */ 1586 if (in6p && (in6p->in6p_flags & IN6P_CONTROLOPTS)) { 1587 if (in6p->in6p_options) { 1588 m_freem(in6p->in6p_options); 1589 in6p->in6p_options = 0; 1590 } 1591 KASSERT(ip6 != NULL); 1592 ip6_savecontrol(in6p, &in6p->in6p_options, ip6, m); 1593 } 1594 #endif 1595 1596 if (so->so_options & (SO_DEBUG|SO_ACCEPTCONN)) { 1597 union syn_cache_sa src; 1598 union syn_cache_sa dst; 1599 1600 memset(&src, 0, sizeof(src)); 1601 memset(&dst, 0, sizeof(dst)); 1602 switch (af) { 1603 #ifdef INET 1604 case AF_INET: 1605 src.sin.sin_len = sizeof(struct sockaddr_in); 1606 src.sin.sin_family = AF_INET; 1607 src.sin.sin_addr = ip->ip_src; 1608 src.sin.sin_port = th->th_sport; 1609 1610 dst.sin.sin_len = sizeof(struct sockaddr_in); 1611 dst.sin.sin_family = AF_INET; 1612 dst.sin.sin_addr = ip->ip_dst; 1613 dst.sin.sin_port = th->th_dport; 1614 break; 1615 #endif 1616 #ifdef INET6 1617 case AF_INET6: 1618 src.sin6.sin6_len = sizeof(struct sockaddr_in6); 1619 src.sin6.sin6_family = AF_INET6; 1620 src.sin6.sin6_addr = ip6->ip6_src; 1621 src.sin6.sin6_port = th->th_sport; 1622 1623 dst.sin6.sin6_len = sizeof(struct sockaddr_in6); 1624 dst.sin6.sin6_family = AF_INET6; 1625 dst.sin6.sin6_addr = ip6->ip6_dst; 1626 dst.sin6.sin6_port = th->th_dport; 1627 break; 1628 #endif /* INET6 */ 1629 default: 1630 goto badsyn; /*sanity*/ 1631 } 1632 1633 if (so->so_options & SO_DEBUG) { 1634 #ifdef TCP_DEBUG 1635 ostate = tp->t_state; 1636 #endif 1637 1638 tcp_saveti = NULL; 1639 if (iphlen + sizeof(struct tcphdr) > MHLEN) 1640 goto nosave; 1641 1642 if (m->m_len > iphlen && (m->m_flags & M_EXT) == 0) { 1643 tcp_saveti = m_copym(m, 0, iphlen, M_DONTWAIT); 1644 if (!tcp_saveti) 1645 goto nosave; 1646 } else { 1647 MGETHDR(tcp_saveti, M_DONTWAIT, MT_HEADER); 1648 if (!tcp_saveti) 1649 goto nosave; 1650 MCLAIM(m, &tcp_mowner); 1651 tcp_saveti->m_len = iphlen; 1652 m_copydata(m, 0, iphlen, 1653 mtod(tcp_saveti, void *)); 1654 } 1655 1656 if (M_TRAILINGSPACE(tcp_saveti) < sizeof(struct tcphdr)) { 1657 m_freem(tcp_saveti); 1658 tcp_saveti = NULL; 1659 } else { 1660 tcp_saveti->m_len += sizeof(struct tcphdr); 1661 memcpy(mtod(tcp_saveti, char *) + iphlen, th, 1662 sizeof(struct tcphdr)); 1663 } 1664 nosave:; 1665 } 1666 if (so->so_options & SO_ACCEPTCONN) { 1667 if ((tiflags & (TH_RST|TH_ACK|TH_SYN)) != TH_SYN) { 1668 if (tiflags & TH_RST) { 1669 syn_cache_reset(&src.sa, &dst.sa, th); 1670 } else if ((tiflags & (TH_ACK|TH_SYN)) == 1671 (TH_ACK|TH_SYN)) { 1672 /* 1673 * Received a SYN,ACK. This should 1674 * never happen while we are in 1675 * LISTEN. Send an RST. 1676 */ 1677 goto badsyn; 1678 } else if (tiflags & TH_ACK) { 1679 so = syn_cache_get(&src.sa, &dst.sa, 1680 th, toff, tlen, so, m); 1681 if (so == NULL) { 1682 /* 1683 * We don't have a SYN for 1684 * this ACK; send an RST. 1685 */ 1686 goto badsyn; 1687 } else if (so == 1688 (struct socket *)(-1)) { 1689 /* 1690 * We were unable to create 1691 * the connection. If the 1692 * 3-way handshake was 1693 * completed, and RST has 1694 * been sent to the peer. 1695 * Since the mbuf might be 1696 * in use for the reply, 1697 * do not free it. 1698 */ 1699 m = NULL; 1700 } else { 1701 /* 1702 * We have created a 1703 * full-blown connection. 1704 */ 1705 tp = NULL; 1706 inp = NULL; 1707 #ifdef INET6 1708 in6p = NULL; 1709 #endif 1710 switch (so->so_proto->pr_domain->dom_family) { 1711 #ifdef INET 1712 case AF_INET: 1713 inp = sotoinpcb(so); 1714 tp = intotcpcb(inp); 1715 break; 1716 #endif 1717 #ifdef INET6 1718 case AF_INET6: 1719 in6p = sotoin6pcb(so); 1720 tp = in6totcpcb(in6p); 1721 break; 1722 #endif 1723 } 1724 if (tp == NULL) 1725 goto badsyn; /*XXX*/ 1726 tiwin <<= tp->snd_scale; 1727 goto after_listen; 1728 } 1729 } else { 1730 /* 1731 * None of RST, SYN or ACK was set. 1732 * This is an invalid packet for a 1733 * TCB in LISTEN state. Send a RST. 1734 */ 1735 goto badsyn; 1736 } 1737 } else { 1738 /* 1739 * Received a SYN. 1740 * 1741 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN 1742 */ 1743 if (m->m_flags & (M_BCAST|M_MCAST)) 1744 goto drop; 1745 1746 switch (af) { 1747 #ifdef INET6 1748 case AF_INET6: 1749 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) 1750 goto drop; 1751 break; 1752 #endif /* INET6 */ 1753 case AF_INET: 1754 if (IN_MULTICAST(ip->ip_dst.s_addr) || 1755 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 1756 goto drop; 1757 break; 1758 } 1759 1760 #ifdef INET6 1761 /* 1762 * If deprecated address is forbidden, we do 1763 * not accept SYN to deprecated interface 1764 * address to prevent any new inbound 1765 * connection from getting established. 1766 * When we do not accept SYN, we send a TCP 1767 * RST, with deprecated source address (instead 1768 * of dropping it). We compromise it as it is 1769 * much better for peer to send a RST, and 1770 * RST will be the final packet for the 1771 * exchange. 1772 * 1773 * If we do not forbid deprecated addresses, we 1774 * accept the SYN packet. RFC2462 does not 1775 * suggest dropping SYN in this case. 1776 * If we decipher RFC2462 5.5.4, it says like 1777 * this: 1778 * 1. use of deprecated addr with existing 1779 * communication is okay - "SHOULD continue 1780 * to be used" 1781 * 2. use of it with new communication: 1782 * (2a) "SHOULD NOT be used if alternate 1783 * address with sufficient scope is 1784 * available" 1785 * (2b) nothing mentioned otherwise. 1786 * Here we fall into (2b) case as we have no 1787 * choice in our source address selection - we 1788 * must obey the peer. 1789 * 1790 * The wording in RFC2462 is confusing, and 1791 * there are multiple description text for 1792 * deprecated address handling - worse, they 1793 * are not exactly the same. I believe 5.5.4 1794 * is the best one, so we follow 5.5.4. 1795 */ 1796 if (af == AF_INET6 && !ip6_use_deprecated) { 1797 struct in6_ifaddr *ia6; 1798 if ((ia6 = in6ifa_ifpwithaddr(m->m_pkthdr.rcvif, 1799 &ip6->ip6_dst)) && 1800 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) { 1801 tp = NULL; 1802 goto dropwithreset; 1803 } 1804 } 1805 #endif 1806 1807 #if defined(IPSEC) || defined(FAST_IPSEC) 1808 switch (af) { 1809 #ifdef INET 1810 case AF_INET: 1811 if (ipsec4_in_reject_so(m, so)) { 1812 IPSEC_STATINC(IPSEC_STAT_IN_POLVIO); 1813 tp = NULL; 1814 goto dropwithreset; 1815 } 1816 break; 1817 #endif 1818 #ifdef INET6 1819 case AF_INET6: 1820 if (ipsec6_in_reject_so(m, so)) { 1821 IPSEC6_STATINC(IPSEC_STAT_IN_POLVIO); 1822 tp = NULL; 1823 goto dropwithreset; 1824 } 1825 break; 1826 #endif /*INET6*/ 1827 } 1828 #endif /*IPSEC*/ 1829 1830 /* 1831 * LISTEN socket received a SYN 1832 * from itself? This can't possibly 1833 * be valid; drop the packet. 1834 */ 1835 if (th->th_sport == th->th_dport) { 1836 int i; 1837 1838 switch (af) { 1839 #ifdef INET 1840 case AF_INET: 1841 i = in_hosteq(ip->ip_src, ip->ip_dst); 1842 break; 1843 #endif 1844 #ifdef INET6 1845 case AF_INET6: 1846 i = IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &ip6->ip6_dst); 1847 break; 1848 #endif 1849 default: 1850 i = 1; 1851 } 1852 if (i) { 1853 TCP_STATINC(TCP_STAT_BADSYN); 1854 goto drop; 1855 } 1856 } 1857 1858 /* 1859 * SYN looks ok; create compressed TCP 1860 * state for it. 1861 */ 1862 if (so->so_qlen <= so->so_qlimit && 1863 syn_cache_add(&src.sa, &dst.sa, th, tlen, 1864 so, m, optp, optlen, &opti)) 1865 m = NULL; 1866 } 1867 goto drop; 1868 } 1869 } 1870 1871 after_listen: 1872 #ifdef DIAGNOSTIC 1873 /* 1874 * Should not happen now that all embryonic connections 1875 * are handled with compressed state. 1876 */ 1877 if (tp->t_state == TCPS_LISTEN) 1878 panic("tcp_input: TCPS_LISTEN"); 1879 #endif 1880 1881 /* 1882 * Segment received on connection. 1883 * Reset idle time and keep-alive timer. 1884 */ 1885 tp->t_rcvtime = tcp_now; 1886 if (TCPS_HAVEESTABLISHED(tp->t_state)) 1887 TCP_TIMER_ARM(tp, TCPT_KEEP, tp->t_keepidle); 1888 1889 /* 1890 * Process options. 1891 */ 1892 #ifdef TCP_SIGNATURE 1893 if (optp || (tp->t_flags & TF_SIGNATURE)) 1894 #else 1895 if (optp) 1896 #endif 1897 if (tcp_dooptions(tp, optp, optlen, th, m, toff, &opti) < 0) 1898 goto drop; 1899 1900 if (TCP_SACK_ENABLED(tp)) { 1901 tcp_del_sackholes(tp, th); 1902 } 1903 1904 if (TCP_ECN_ALLOWED(tp)) { 1905 if (tiflags & TH_CWR) { 1906 tp->t_flags &= ~TF_ECN_SND_ECE; 1907 } 1908 switch (iptos & IPTOS_ECN_MASK) { 1909 case IPTOS_ECN_CE: 1910 tp->t_flags |= TF_ECN_SND_ECE; 1911 TCP_STATINC(TCP_STAT_ECN_CE); 1912 break; 1913 case IPTOS_ECN_ECT0: 1914 TCP_STATINC(TCP_STAT_ECN_ECT); 1915 break; 1916 case IPTOS_ECN_ECT1: 1917 /* XXX: ignore for now -- rpaulo */ 1918 break; 1919 } 1920 /* 1921 * Congestion experienced. 1922 * Ignore if we are already trying to recover. 1923 */ 1924 if ((tiflags & TH_ECE) && SEQ_GEQ(tp->snd_una, tp->snd_recover)) 1925 tp->t_congctl->cong_exp(tp); 1926 } 1927 1928 if (opti.ts_present && opti.ts_ecr) { 1929 /* 1930 * Calculate the RTT from the returned time stamp and the 1931 * connection's time base. If the time stamp is later than 1932 * the current time, or is extremely old, fall back to non-1323 1933 * RTT calculation. Since ts_rtt is unsigned, we can test both 1934 * at the same time. 1935 * 1936 * Note that ts_rtt is in units of slow ticks (500 1937 * ms). Since most earthbound RTTs are < 500 ms, 1938 * observed values will have large quantization noise. 1939 * Our smoothed RTT is then the fraction of observed 1940 * samples that are 1 tick instead of 0 (times 500 1941 * ms). 1942 * 1943 * ts_rtt is increased by 1 to denote a valid sample, 1944 * with 0 indicating an invalid measurement. This 1945 * extra 1 must be removed when ts_rtt is used, or 1946 * else an an erroneous extra 500 ms will result. 1947 */ 1948 ts_rtt = TCP_TIMESTAMP(tp) - opti.ts_ecr + 1; 1949 if (ts_rtt > TCP_PAWS_IDLE) 1950 ts_rtt = 0; 1951 } else { 1952 ts_rtt = 0; 1953 } 1954 1955 /* 1956 * Header prediction: check for the two common cases 1957 * of a uni-directional data xfer. If the packet has 1958 * no control flags, is in-sequence, the window didn't 1959 * change and we're not retransmitting, it's a 1960 * candidate. If the length is zero and the ack moved 1961 * forward, we're the sender side of the xfer. Just 1962 * free the data acked & wake any higher level process 1963 * that was blocked waiting for space. If the length 1964 * is non-zero and the ack didn't move, we're the 1965 * receiver side. If we're getting packets in-order 1966 * (the reassembly queue is empty), add the data to 1967 * the socket buffer and note that we need a delayed ack. 1968 */ 1969 if (tp->t_state == TCPS_ESTABLISHED && 1970 (tiflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ECE|TH_CWR|TH_ACK)) 1971 == TH_ACK && 1972 (!opti.ts_present || TSTMP_GEQ(opti.ts_val, tp->ts_recent)) && 1973 th->th_seq == tp->rcv_nxt && 1974 tiwin && tiwin == tp->snd_wnd && 1975 tp->snd_nxt == tp->snd_max) { 1976 1977 /* 1978 * If last ACK falls within this segment's sequence numbers, 1979 * record the timestamp. 1980 * NOTE that the test is modified according to the latest 1981 * proposal of the tcplw (at) cray.com list (Braden 1993/04/26). 1982 * 1983 * note that we already know 1984 * TSTMP_GEQ(opti.ts_val, tp->ts_recent) 1985 */ 1986 if (opti.ts_present && 1987 SEQ_LEQ(th->th_seq, tp->last_ack_sent)) { 1988 tp->ts_recent_age = tcp_now; 1989 tp->ts_recent = opti.ts_val; 1990 } 1991 1992 if (tlen == 0) { 1993 /* Ack prediction. */ 1994 if (SEQ_GT(th->th_ack, tp->snd_una) && 1995 SEQ_LEQ(th->th_ack, tp->snd_max) && 1996 tp->snd_cwnd >= tp->snd_wnd && 1997 tp->t_partialacks < 0) { 1998 /* 1999 * this is a pure ack for outstanding data. 2000 */ 2001 if (ts_rtt) 2002 tcp_xmit_timer(tp, ts_rtt - 1); 2003 else if (tp->t_rtttime && 2004 SEQ_GT(th->th_ack, tp->t_rtseq)) 2005 tcp_xmit_timer(tp, 2006 tcp_now - tp->t_rtttime); 2007 acked = th->th_ack - tp->snd_una; 2008 tcps = TCP_STAT_GETREF(); 2009 tcps[TCP_STAT_PREDACK]++; 2010 tcps[TCP_STAT_RCVACKPACK]++; 2011 tcps[TCP_STAT_RCVACKBYTE] += acked; 2012 TCP_STAT_PUTREF(); 2013 nd6_hint(tp); 2014 2015 if (acked > (tp->t_lastoff - tp->t_inoff)) 2016 tp->t_lastm = NULL; 2017 sbdrop(&so->so_snd, acked); 2018 tp->t_lastoff -= acked; 2019 2020 icmp_check(tp, th, acked); 2021 2022 tp->snd_una = th->th_ack; 2023 tp->snd_fack = tp->snd_una; 2024 if (SEQ_LT(tp->snd_high, tp->snd_una)) 2025 tp->snd_high = tp->snd_una; 2026 m_freem(m); 2027 2028 /* 2029 * If all outstanding data are acked, stop 2030 * retransmit timer, otherwise restart timer 2031 * using current (possibly backed-off) value. 2032 * If process is waiting for space, 2033 * wakeup/selnotify/signal. If data 2034 * are ready to send, let tcp_output 2035 * decide between more output or persist. 2036 */ 2037 if (tp->snd_una == tp->snd_max) 2038 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2039 else if (TCP_TIMER_ISARMED(tp, 2040 TCPT_PERSIST) == 0) 2041 TCP_TIMER_ARM(tp, TCPT_REXMT, 2042 tp->t_rxtcur); 2043 2044 sowwakeup(so); 2045 if (so->so_snd.sb_cc) { 2046 KERNEL_LOCK(1, NULL); 2047 (void) tcp_output(tp); 2048 KERNEL_UNLOCK_ONE(NULL); 2049 } 2050 if (tcp_saveti) 2051 m_freem(tcp_saveti); 2052 return; 2053 } 2054 } else if (th->th_ack == tp->snd_una && 2055 TAILQ_FIRST(&tp->segq) == NULL && 2056 tlen <= sbspace(&so->so_rcv)) { 2057 int newsize = 0; /* automatic sockbuf scaling */ 2058 2059 /* 2060 * this is a pure, in-sequence data packet 2061 * with nothing on the reassembly queue and 2062 * we have enough buffer space to take it. 2063 */ 2064 tp->rcv_nxt += tlen; 2065 tcps = TCP_STAT_GETREF(); 2066 tcps[TCP_STAT_PREDDAT]++; 2067 tcps[TCP_STAT_RCVPACK]++; 2068 tcps[TCP_STAT_RCVBYTE] += tlen; 2069 TCP_STAT_PUTREF(); 2070 nd6_hint(tp); 2071 2072 /* 2073 * Automatic sizing enables the performance of large buffers 2074 * and most of the efficiency of small ones by only allocating 2075 * space when it is needed. 2076 * 2077 * On the receive side the socket buffer memory is only rarely 2078 * used to any significant extent. This allows us to be much 2079 * more aggressive in scaling the receive socket buffer. For 2080 * the case that the buffer space is actually used to a large 2081 * extent and we run out of kernel memory we can simply drop 2082 * the new segments; TCP on the sender will just retransmit it 2083 * later. Setting the buffer size too big may only consume too 2084 * much kernel memory if the application doesn't read() from 2085 * the socket or packet loss or reordering makes use of the 2086 * reassembly queue. 2087 * 2088 * The criteria to step up the receive buffer one notch are: 2089 * 1. the number of bytes received during the time it takes 2090 * one timestamp to be reflected back to us (the RTT); 2091 * 2. received bytes per RTT is within seven eighth of the 2092 * current socket buffer size; 2093 * 3. receive buffer size has not hit maximal automatic size; 2094 * 2095 * This algorithm does one step per RTT at most and only if 2096 * we receive a bulk stream w/o packet losses or reorderings. 2097 * Shrinking the buffer during idle times is not necessary as 2098 * it doesn't consume any memory when idle. 2099 * 2100 * TODO: Only step up if the application is actually serving 2101 * the buffer to better manage the socket buffer resources. 2102 */ 2103 if (tcp_do_autorcvbuf && 2104 opti.ts_ecr && 2105 (so->so_rcv.sb_flags & SB_AUTOSIZE)) { 2106 if (opti.ts_ecr > tp->rfbuf_ts && 2107 opti.ts_ecr - tp->rfbuf_ts < PR_SLOWHZ) { 2108 if (tp->rfbuf_cnt > 2109 (so->so_rcv.sb_hiwat / 8 * 7) && 2110 so->so_rcv.sb_hiwat < 2111 tcp_autorcvbuf_max) { 2112 newsize = 2113 min(so->so_rcv.sb_hiwat + 2114 tcp_autorcvbuf_inc, 2115 tcp_autorcvbuf_max); 2116 } 2117 /* Start over with next RTT. */ 2118 tp->rfbuf_ts = 0; 2119 tp->rfbuf_cnt = 0; 2120 } else 2121 tp->rfbuf_cnt += tlen; /* add up */ 2122 } 2123 2124 /* 2125 * Drop TCP, IP headers and TCP options then add data 2126 * to socket buffer. 2127 */ 2128 if (so->so_state & SS_CANTRCVMORE) 2129 m_freem(m); 2130 else { 2131 /* 2132 * Set new socket buffer size. 2133 * Give up when limit is reached. 2134 */ 2135 if (newsize) 2136 if (!sbreserve(&so->so_rcv, 2137 newsize, so)) 2138 so->so_rcv.sb_flags &= ~SB_AUTOSIZE; 2139 m_adj(m, toff + off); 2140 sbappendstream(&so->so_rcv, m); 2141 } 2142 sorwakeup(so); 2143 tcp_setup_ack(tp, th); 2144 if (tp->t_flags & TF_ACKNOW) { 2145 KERNEL_LOCK(1, NULL); 2146 (void) tcp_output(tp); 2147 KERNEL_UNLOCK_ONE(NULL); 2148 } 2149 if (tcp_saveti) 2150 m_freem(tcp_saveti); 2151 return; 2152 } 2153 } 2154 2155 /* 2156 * Compute mbuf offset to TCP data segment. 2157 */ 2158 hdroptlen = toff + off; 2159 2160 /* 2161 * Calculate amount of space in receive window, 2162 * and then do TCP input processing. 2163 * Receive window is amount of space in rcv queue, 2164 * but not less than advertised window. 2165 */ 2166 { int win; 2167 2168 win = sbspace(&so->so_rcv); 2169 if (win < 0) 2170 win = 0; 2171 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 2172 } 2173 2174 /* Reset receive buffer auto scaling when not in bulk receive mode. */ 2175 tp->rfbuf_ts = 0; 2176 tp->rfbuf_cnt = 0; 2177 2178 switch (tp->t_state) { 2179 /* 2180 * If the state is SYN_SENT: 2181 * if seg contains an ACK, but not for our SYN, drop the input. 2182 * if seg contains a RST, then drop the connection. 2183 * if seg does not contain SYN, then drop it. 2184 * Otherwise this is an acceptable SYN segment 2185 * initialize tp->rcv_nxt and tp->irs 2186 * if seg contains ack then advance tp->snd_una 2187 * if seg contains a ECE and ECN support is enabled, the stream 2188 * is ECN capable. 2189 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 2190 * arrange for segment to be acked (eventually) 2191 * continue processing rest of data/controls, beginning with URG 2192 */ 2193 case TCPS_SYN_SENT: 2194 if ((tiflags & TH_ACK) && 2195 (SEQ_LEQ(th->th_ack, tp->iss) || 2196 SEQ_GT(th->th_ack, tp->snd_max))) 2197 goto dropwithreset; 2198 if (tiflags & TH_RST) { 2199 if (tiflags & TH_ACK) 2200 tp = tcp_drop(tp, ECONNREFUSED); 2201 goto drop; 2202 } 2203 if ((tiflags & TH_SYN) == 0) 2204 goto drop; 2205 if (tiflags & TH_ACK) { 2206 tp->snd_una = th->th_ack; 2207 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2208 tp->snd_nxt = tp->snd_una; 2209 if (SEQ_LT(tp->snd_high, tp->snd_una)) 2210 tp->snd_high = tp->snd_una; 2211 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2212 2213 if ((tiflags & TH_ECE) && tcp_do_ecn) { 2214 tp->t_flags |= TF_ECN_PERMIT; 2215 TCP_STATINC(TCP_STAT_ECN_SHS); 2216 } 2217 2218 } 2219 tp->irs = th->th_seq; 2220 tcp_rcvseqinit(tp); 2221 tp->t_flags |= TF_ACKNOW; 2222 tcp_mss_from_peer(tp, opti.maxseg); 2223 2224 /* 2225 * Initialize the initial congestion window. If we 2226 * had to retransmit the SYN, we must initialize cwnd 2227 * to 1 segment (i.e. the Loss Window). 2228 */ 2229 if (tp->t_flags & TF_SYN_REXMT) 2230 tp->snd_cwnd = tp->t_peermss; 2231 else { 2232 int ss = tcp_init_win; 2233 #ifdef INET 2234 if (inp != NULL && in_localaddr(inp->inp_faddr)) 2235 ss = tcp_init_win_local; 2236 #endif 2237 #ifdef INET6 2238 if (in6p != NULL && in6_localaddr(&in6p->in6p_faddr)) 2239 ss = tcp_init_win_local; 2240 #endif 2241 tp->snd_cwnd = TCP_INITIAL_WINDOW(ss, tp->t_peermss); 2242 } 2243 2244 tcp_rmx_rtt(tp); 2245 if (tiflags & TH_ACK) { 2246 TCP_STATINC(TCP_STAT_CONNECTS); 2247 /* 2248 * move tcp_established before soisconnected 2249 * because upcall handler can drive tcp_output 2250 * functionality. 2251 * XXX we might call soisconnected at the end of 2252 * all processing 2253 */ 2254 tcp_established(tp); 2255 soisconnected(so); 2256 /* Do window scaling on this connection? */ 2257 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2258 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2259 tp->snd_scale = tp->requested_s_scale; 2260 tp->rcv_scale = tp->request_r_scale; 2261 } 2262 TCP_REASS_LOCK(tp); 2263 (void) tcp_reass(tp, NULL, (struct mbuf *)0, &tlen); 2264 /* 2265 * if we didn't have to retransmit the SYN, 2266 * use its rtt as our initial srtt & rtt var. 2267 */ 2268 if (tp->t_rtttime) 2269 tcp_xmit_timer(tp, tcp_now - tp->t_rtttime); 2270 } else 2271 tp->t_state = TCPS_SYN_RECEIVED; 2272 2273 /* 2274 * Advance th->th_seq to correspond to first data byte. 2275 * If data, trim to stay within window, 2276 * dropping FIN if necessary. 2277 */ 2278 th->th_seq++; 2279 if (tlen > tp->rcv_wnd) { 2280 todrop = tlen - tp->rcv_wnd; 2281 m_adj(m, -todrop); 2282 tlen = tp->rcv_wnd; 2283 tiflags &= ~TH_FIN; 2284 tcps = TCP_STAT_GETREF(); 2285 tcps[TCP_STAT_RCVPACKAFTERWIN]++; 2286 tcps[TCP_STAT_RCVBYTEAFTERWIN] += todrop; 2287 TCP_STAT_PUTREF(); 2288 } 2289 tp->snd_wl1 = th->th_seq - 1; 2290 tp->rcv_up = th->th_seq; 2291 goto step6; 2292 2293 /* 2294 * If the state is SYN_RECEIVED: 2295 * If seg contains an ACK, but not for our SYN, drop the input 2296 * and generate an RST. See page 36, rfc793 2297 */ 2298 case TCPS_SYN_RECEIVED: 2299 if ((tiflags & TH_ACK) && 2300 (SEQ_LEQ(th->th_ack, tp->iss) || 2301 SEQ_GT(th->th_ack, tp->snd_max))) 2302 goto dropwithreset; 2303 break; 2304 } 2305 2306 /* 2307 * States other than LISTEN or SYN_SENT. 2308 * First check timestamp, if present. 2309 * Then check that at least some bytes of segment are within 2310 * receive window. If segment begins before rcv_nxt, 2311 * drop leading data (and SYN); if nothing left, just ack. 2312 * 2313 * RFC 1323 PAWS: If we have a timestamp reply on this segment 2314 * and it's less than ts_recent, drop it. 2315 */ 2316 if (opti.ts_present && (tiflags & TH_RST) == 0 && tp->ts_recent && 2317 TSTMP_LT(opti.ts_val, tp->ts_recent)) { 2318 2319 /* Check to see if ts_recent is over 24 days old. */ 2320 if (tcp_now - tp->ts_recent_age > TCP_PAWS_IDLE) { 2321 /* 2322 * Invalidate ts_recent. If this segment updates 2323 * ts_recent, the age will be reset later and ts_recent 2324 * will get a valid value. If it does not, setting 2325 * ts_recent to zero will at least satisfy the 2326 * requirement that zero be placed in the timestamp 2327 * echo reply when ts_recent isn't valid. The 2328 * age isn't reset until we get a valid ts_recent 2329 * because we don't want out-of-order segments to be 2330 * dropped when ts_recent is old. 2331 */ 2332 tp->ts_recent = 0; 2333 } else { 2334 tcps = TCP_STAT_GETREF(); 2335 tcps[TCP_STAT_RCVDUPPACK]++; 2336 tcps[TCP_STAT_RCVDUPBYTE] += tlen; 2337 tcps[TCP_STAT_PAWSDROP]++; 2338 TCP_STAT_PUTREF(); 2339 tcp_new_dsack(tp, th->th_seq, tlen); 2340 goto dropafterack; 2341 } 2342 } 2343 2344 todrop = tp->rcv_nxt - th->th_seq; 2345 dupseg = false; 2346 if (todrop > 0) { 2347 if (tiflags & TH_SYN) { 2348 tiflags &= ~TH_SYN; 2349 th->th_seq++; 2350 if (th->th_urp > 1) 2351 th->th_urp--; 2352 else { 2353 tiflags &= ~TH_URG; 2354 th->th_urp = 0; 2355 } 2356 todrop--; 2357 } 2358 if (todrop > tlen || 2359 (todrop == tlen && (tiflags & TH_FIN) == 0)) { 2360 /* 2361 * Any valid FIN or RST must be to the left of the 2362 * window. At this point the FIN or RST must be a 2363 * duplicate or out of sequence; drop it. 2364 */ 2365 if (tiflags & TH_RST) 2366 goto drop; 2367 tiflags &= ~(TH_FIN|TH_RST); 2368 /* 2369 * Send an ACK to resynchronize and drop any data. 2370 * But keep on processing for RST or ACK. 2371 */ 2372 tp->t_flags |= TF_ACKNOW; 2373 todrop = tlen; 2374 dupseg = true; 2375 tcps = TCP_STAT_GETREF(); 2376 tcps[TCP_STAT_RCVDUPPACK]++; 2377 tcps[TCP_STAT_RCVDUPBYTE] += todrop; 2378 TCP_STAT_PUTREF(); 2379 } else if ((tiflags & TH_RST) && 2380 th->th_seq != tp->rcv_nxt) { 2381 /* 2382 * Test for reset before adjusting the sequence 2383 * number for overlapping data. 2384 */ 2385 goto dropafterack_ratelim; 2386 } else { 2387 tcps = TCP_STAT_GETREF(); 2388 tcps[TCP_STAT_RCVPARTDUPPACK]++; 2389 tcps[TCP_STAT_RCVPARTDUPBYTE] += todrop; 2390 TCP_STAT_PUTREF(); 2391 } 2392 tcp_new_dsack(tp, th->th_seq, todrop); 2393 hdroptlen += todrop; /*drop from head afterwards*/ 2394 th->th_seq += todrop; 2395 tlen -= todrop; 2396 if (th->th_urp > todrop) 2397 th->th_urp -= todrop; 2398 else { 2399 tiflags &= ~TH_URG; 2400 th->th_urp = 0; 2401 } 2402 } 2403 2404 /* 2405 * If new data are received on a connection after the 2406 * user processes are gone, then RST the other end. 2407 */ 2408 if ((so->so_state & SS_NOFDREF) && 2409 tp->t_state > TCPS_CLOSE_WAIT && tlen) { 2410 tp = tcp_close(tp); 2411 TCP_STATINC(TCP_STAT_RCVAFTERCLOSE); 2412 goto dropwithreset; 2413 } 2414 2415 /* 2416 * If segment ends after window, drop trailing data 2417 * (and PUSH and FIN); if nothing left, just ACK. 2418 */ 2419 todrop = (th->th_seq + tlen) - (tp->rcv_nxt+tp->rcv_wnd); 2420 if (todrop > 0) { 2421 TCP_STATINC(TCP_STAT_RCVPACKAFTERWIN); 2422 if (todrop >= tlen) { 2423 /* 2424 * The segment actually starts after the window. 2425 * th->th_seq + tlen - tp->rcv_nxt - tp->rcv_wnd >= tlen 2426 * th->th_seq - tp->rcv_nxt - tp->rcv_wnd >= 0 2427 * th->th_seq >= tp->rcv_nxt + tp->rcv_wnd 2428 */ 2429 TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, tlen); 2430 /* 2431 * If a new connection request is received 2432 * while in TIME_WAIT, drop the old connection 2433 * and start over if the sequence numbers 2434 * are above the previous ones. 2435 * 2436 * NOTE: We will checksum the packet again, and 2437 * so we need to put the header fields back into 2438 * network order! 2439 * XXX This kind of sucks, but we don't expect 2440 * XXX this to happen very often, so maybe it 2441 * XXX doesn't matter so much. 2442 */ 2443 if (tiflags & TH_SYN && 2444 tp->t_state == TCPS_TIME_WAIT && 2445 SEQ_GT(th->th_seq, tp->rcv_nxt)) { 2446 tp = tcp_close(tp); 2447 tcp_fields_to_net(th); 2448 goto findpcb; 2449 } 2450 /* 2451 * If window is closed can only take segments at 2452 * window edge, and have to drop data and PUSH from 2453 * incoming segments. Continue processing, but 2454 * remember to ack. Otherwise, drop segment 2455 * and (if not RST) ack. 2456 */ 2457 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 2458 tp->t_flags |= TF_ACKNOW; 2459 TCP_STATINC(TCP_STAT_RCVWINPROBE); 2460 } else 2461 goto dropafterack; 2462 } else 2463 TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, todrop); 2464 m_adj(m, -todrop); 2465 tlen -= todrop; 2466 tiflags &= ~(TH_PUSH|TH_FIN); 2467 } 2468 2469 /* 2470 * If last ACK falls within this segment's sequence numbers, 2471 * record the timestamp. 2472 * NOTE: 2473 * 1) That the test incorporates suggestions from the latest 2474 * proposal of the tcplw (at) cray.com list (Braden 1993/04/26). 2475 * 2) That updating only on newer timestamps interferes with 2476 * our earlier PAWS tests, so this check should be solely 2477 * predicated on the sequence space of this segment. 2478 * 3) That we modify the segment boundary check to be 2479 * Last.ACK.Sent <= SEG.SEQ + SEG.Len 2480 * instead of RFC1323's 2481 * Last.ACK.Sent < SEG.SEQ + SEG.Len, 2482 * This modified check allows us to overcome RFC1323's 2483 * limitations as described in Stevens TCP/IP Illustrated 2484 * Vol. 2 p.869. In such cases, we can still calculate the 2485 * RTT correctly when RCV.NXT == Last.ACK.Sent. 2486 */ 2487 if (opti.ts_present && 2488 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 2489 SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen + 2490 ((tiflags & (TH_SYN|TH_FIN)) != 0))) { 2491 tp->ts_recent_age = tcp_now; 2492 tp->ts_recent = opti.ts_val; 2493 } 2494 2495 /* 2496 * If the RST bit is set examine the state: 2497 * SYN_RECEIVED STATE: 2498 * If passive open, return to LISTEN state. 2499 * If active open, inform user that connection was refused. 2500 * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES: 2501 * Inform user that connection was reset, and close tcb. 2502 * CLOSING, LAST_ACK, TIME_WAIT STATES 2503 * Close the tcb. 2504 */ 2505 if (tiflags & TH_RST) { 2506 if (th->th_seq != tp->rcv_nxt) 2507 goto dropafterack_ratelim; 2508 2509 switch (tp->t_state) { 2510 case TCPS_SYN_RECEIVED: 2511 so->so_error = ECONNREFUSED; 2512 goto close; 2513 2514 case TCPS_ESTABLISHED: 2515 case TCPS_FIN_WAIT_1: 2516 case TCPS_FIN_WAIT_2: 2517 case TCPS_CLOSE_WAIT: 2518 so->so_error = ECONNRESET; 2519 close: 2520 tp->t_state = TCPS_CLOSED; 2521 TCP_STATINC(TCP_STAT_DROPS); 2522 tp = tcp_close(tp); 2523 goto drop; 2524 2525 case TCPS_CLOSING: 2526 case TCPS_LAST_ACK: 2527 case TCPS_TIME_WAIT: 2528 tp = tcp_close(tp); 2529 goto drop; 2530 } 2531 } 2532 2533 /* 2534 * Since we've covered the SYN-SENT and SYN-RECEIVED states above 2535 * we must be in a synchronized state. RFC791 states (under RST 2536 * generation) that any unacceptable segment (an out-of-order SYN 2537 * qualifies) received in a synchronized state must elicit only an 2538 * empty acknowledgment segment ... and the connection remains in 2539 * the same state. 2540 */ 2541 if (tiflags & TH_SYN) { 2542 if (tp->rcv_nxt == th->th_seq) { 2543 tcp_respond(tp, m, m, th, (tcp_seq)0, th->th_ack - 1, 2544 TH_ACK); 2545 if (tcp_saveti) 2546 m_freem(tcp_saveti); 2547 return; 2548 } 2549 2550 goto dropafterack_ratelim; 2551 } 2552 2553 /* 2554 * If the ACK bit is off we drop the segment and return. 2555 */ 2556 if ((tiflags & TH_ACK) == 0) { 2557 if (tp->t_flags & TF_ACKNOW) 2558 goto dropafterack; 2559 else 2560 goto drop; 2561 } 2562 2563 /* 2564 * Ack processing. 2565 */ 2566 switch (tp->t_state) { 2567 2568 /* 2569 * In SYN_RECEIVED state if the ack ACKs our SYN then enter 2570 * ESTABLISHED state and continue processing, otherwise 2571 * send an RST. 2572 */ 2573 case TCPS_SYN_RECEIVED: 2574 if (SEQ_GT(tp->snd_una, th->th_ack) || 2575 SEQ_GT(th->th_ack, tp->snd_max)) 2576 goto dropwithreset; 2577 TCP_STATINC(TCP_STAT_CONNECTS); 2578 soisconnected(so); 2579 tcp_established(tp); 2580 /* Do window scaling? */ 2581 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2582 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2583 tp->snd_scale = tp->requested_s_scale; 2584 tp->rcv_scale = tp->request_r_scale; 2585 } 2586 TCP_REASS_LOCK(tp); 2587 (void) tcp_reass(tp, NULL, (struct mbuf *)0, &tlen); 2588 tp->snd_wl1 = th->th_seq - 1; 2589 /* fall into ... */ 2590 2591 /* 2592 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 2593 * ACKs. If the ack is in the range 2594 * tp->snd_una < th->th_ack <= tp->snd_max 2595 * then advance tp->snd_una to th->th_ack and drop 2596 * data from the retransmission queue. If this ACK reflects 2597 * more up to date window information we update our window information. 2598 */ 2599 case TCPS_ESTABLISHED: 2600 case TCPS_FIN_WAIT_1: 2601 case TCPS_FIN_WAIT_2: 2602 case TCPS_CLOSE_WAIT: 2603 case TCPS_CLOSING: 2604 case TCPS_LAST_ACK: 2605 case TCPS_TIME_WAIT: 2606 2607 if (SEQ_LEQ(th->th_ack, tp->snd_una)) { 2608 if (tlen == 0 && !dupseg && tiwin == tp->snd_wnd) { 2609 TCP_STATINC(TCP_STAT_RCVDUPACK); 2610 /* 2611 * If we have outstanding data (other than 2612 * a window probe), this is a completely 2613 * duplicate ack (ie, window info didn't 2614 * change), the ack is the biggest we've 2615 * seen and we've seen exactly our rexmt 2616 * threshhold of them, assume a packet 2617 * has been dropped and retransmit it. 2618 * Kludge snd_nxt & the congestion 2619 * window so we send only this one 2620 * packet. 2621 */ 2622 if (TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 || 2623 th->th_ack != tp->snd_una) 2624 tp->t_dupacks = 0; 2625 else if (tp->t_partialacks < 0 && 2626 (++tp->t_dupacks == tcprexmtthresh || 2627 TCP_FACK_FASTRECOV(tp))) { 2628 /* 2629 * Do the fast retransmit, and adjust 2630 * congestion control paramenters. 2631 */ 2632 if (tp->t_congctl->fast_retransmit(tp, th)) { 2633 /* False fast retransmit */ 2634 break; 2635 } else 2636 goto drop; 2637 } else if (tp->t_dupacks > tcprexmtthresh) { 2638 tp->snd_cwnd += tp->t_segsz; 2639 KERNEL_LOCK(1, NULL); 2640 (void) tcp_output(tp); 2641 KERNEL_UNLOCK_ONE(NULL); 2642 goto drop; 2643 } 2644 } else { 2645 /* 2646 * If the ack appears to be very old, only 2647 * allow data that is in-sequence. This 2648 * makes it somewhat more difficult to insert 2649 * forged data by guessing sequence numbers. 2650 * Sent an ack to try to update the send 2651 * sequence number on the other side. 2652 */ 2653 if (tlen && th->th_seq != tp->rcv_nxt && 2654 SEQ_LT(th->th_ack, 2655 tp->snd_una - tp->max_sndwnd)) 2656 goto dropafterack; 2657 } 2658 break; 2659 } 2660 /* 2661 * If the congestion window was inflated to account 2662 * for the other side's cached packets, retract it. 2663 */ 2664 /* XXX: make SACK have his own congestion control 2665 * struct -- rpaulo */ 2666 if (TCP_SACK_ENABLED(tp)) 2667 tcp_sack_newack(tp, th); 2668 else 2669 tp->t_congctl->fast_retransmit_newack(tp, th); 2670 if (SEQ_GT(th->th_ack, tp->snd_max)) { 2671 TCP_STATINC(TCP_STAT_RCVACKTOOMUCH); 2672 goto dropafterack; 2673 } 2674 acked = th->th_ack - tp->snd_una; 2675 tcps = TCP_STAT_GETREF(); 2676 tcps[TCP_STAT_RCVACKPACK]++; 2677 tcps[TCP_STAT_RCVACKBYTE] += acked; 2678 TCP_STAT_PUTREF(); 2679 2680 /* 2681 * If we have a timestamp reply, update smoothed 2682 * round trip time. If no timestamp is present but 2683 * transmit timer is running and timed sequence 2684 * number was acked, update smoothed round trip time. 2685 * Since we now have an rtt measurement, cancel the 2686 * timer backoff (cf., Phil Karn's retransmit alg.). 2687 * Recompute the initial retransmit timer. 2688 */ 2689 if (ts_rtt) 2690 tcp_xmit_timer(tp, ts_rtt - 1); 2691 else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) 2692 tcp_xmit_timer(tp, tcp_now - tp->t_rtttime); 2693 2694 /* 2695 * If all outstanding data is acked, stop retransmit 2696 * timer and remember to restart (more output or persist). 2697 * If there is more data to be acked, restart retransmit 2698 * timer, using current (possibly backed-off) value. 2699 */ 2700 if (th->th_ack == tp->snd_max) { 2701 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2702 needoutput = 1; 2703 } else if (TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) 2704 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 2705 2706 /* 2707 * New data has been acked, adjust the congestion window. 2708 */ 2709 tp->t_congctl->newack(tp, th); 2710 2711 nd6_hint(tp); 2712 if (acked > so->so_snd.sb_cc) { 2713 tp->snd_wnd -= so->so_snd.sb_cc; 2714 sbdrop(&so->so_snd, (int)so->so_snd.sb_cc); 2715 ourfinisacked = 1; 2716 } else { 2717 if (acked > (tp->t_lastoff - tp->t_inoff)) 2718 tp->t_lastm = NULL; 2719 sbdrop(&so->so_snd, acked); 2720 tp->t_lastoff -= acked; 2721 tp->snd_wnd -= acked; 2722 ourfinisacked = 0; 2723 } 2724 sowwakeup(so); 2725 2726 icmp_check(tp, th, acked); 2727 2728 tp->snd_una = th->th_ack; 2729 if (SEQ_GT(tp->snd_una, tp->snd_fack)) 2730 tp->snd_fack = tp->snd_una; 2731 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2732 tp->snd_nxt = tp->snd_una; 2733 if (SEQ_LT(tp->snd_high, tp->snd_una)) 2734 tp->snd_high = tp->snd_una; 2735 2736 switch (tp->t_state) { 2737 2738 /* 2739 * In FIN_WAIT_1 STATE in addition to the processing 2740 * for the ESTABLISHED state if our FIN is now acknowledged 2741 * then enter FIN_WAIT_2. 2742 */ 2743 case TCPS_FIN_WAIT_1: 2744 if (ourfinisacked) { 2745 /* 2746 * If we can't receive any more 2747 * data, then closing user can proceed. 2748 * Starting the timer is contrary to the 2749 * specification, but if we don't get a FIN 2750 * we'll hang forever. 2751 */ 2752 if (so->so_state & SS_CANTRCVMORE) { 2753 soisdisconnected(so); 2754 if (tp->t_maxidle > 0) 2755 TCP_TIMER_ARM(tp, TCPT_2MSL, 2756 tp->t_maxidle); 2757 } 2758 tp->t_state = TCPS_FIN_WAIT_2; 2759 } 2760 break; 2761 2762 /* 2763 * In CLOSING STATE in addition to the processing for 2764 * the ESTABLISHED state if the ACK acknowledges our FIN 2765 * then enter the TIME-WAIT state, otherwise ignore 2766 * the segment. 2767 */ 2768 case TCPS_CLOSING: 2769 if (ourfinisacked) { 2770 tp->t_state = TCPS_TIME_WAIT; 2771 tcp_canceltimers(tp); 2772 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * tp->t_msl); 2773 soisdisconnected(so); 2774 } 2775 break; 2776 2777 /* 2778 * In LAST_ACK, we may still be waiting for data to drain 2779 * and/or to be acked, as well as for the ack of our FIN. 2780 * If our FIN is now acknowledged, delete the TCB, 2781 * enter the closed state and return. 2782 */ 2783 case TCPS_LAST_ACK: 2784 if (ourfinisacked) { 2785 tp = tcp_close(tp); 2786 goto drop; 2787 } 2788 break; 2789 2790 /* 2791 * In TIME_WAIT state the only thing that should arrive 2792 * is a retransmission of the remote FIN. Acknowledge 2793 * it and restart the finack timer. 2794 */ 2795 case TCPS_TIME_WAIT: 2796 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * tp->t_msl); 2797 goto dropafterack; 2798 } 2799 } 2800 2801 step6: 2802 /* 2803 * Update window information. 2804 * Don't look at window if no ACK: TAC's send garbage on first SYN. 2805 */ 2806 if ((tiflags & TH_ACK) && (SEQ_LT(tp->snd_wl1, th->th_seq) || 2807 (tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) || 2808 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) { 2809 /* keep track of pure window updates */ 2810 if (tlen == 0 && 2811 tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) 2812 TCP_STATINC(TCP_STAT_RCVWINUPD); 2813 tp->snd_wnd = tiwin; 2814 tp->snd_wl1 = th->th_seq; 2815 tp->snd_wl2 = th->th_ack; 2816 if (tp->snd_wnd > tp->max_sndwnd) 2817 tp->max_sndwnd = tp->snd_wnd; 2818 needoutput = 1; 2819 } 2820 2821 /* 2822 * Process segments with URG. 2823 */ 2824 if ((tiflags & TH_URG) && th->th_urp && 2825 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2826 /* 2827 * This is a kludge, but if we receive and accept 2828 * random urgent pointers, we'll crash in 2829 * soreceive. It's hard to imagine someone 2830 * actually wanting to send this much urgent data. 2831 */ 2832 if (th->th_urp + so->so_rcv.sb_cc > sb_max) { 2833 th->th_urp = 0; /* XXX */ 2834 tiflags &= ~TH_URG; /* XXX */ 2835 goto dodata; /* XXX */ 2836 } 2837 /* 2838 * If this segment advances the known urgent pointer, 2839 * then mark the data stream. This should not happen 2840 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 2841 * a FIN has been received from the remote side. 2842 * In these states we ignore the URG. 2843 * 2844 * According to RFC961 (Assigned Protocols), 2845 * the urgent pointer points to the last octet 2846 * of urgent data. We continue, however, 2847 * to consider it to indicate the first octet 2848 * of data past the urgent section as the original 2849 * spec states (in one of two places). 2850 */ 2851 if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) { 2852 tp->rcv_up = th->th_seq + th->th_urp; 2853 so->so_oobmark = so->so_rcv.sb_cc + 2854 (tp->rcv_up - tp->rcv_nxt) - 1; 2855 if (so->so_oobmark == 0) 2856 so->so_state |= SS_RCVATMARK; 2857 sohasoutofband(so); 2858 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); 2859 } 2860 /* 2861 * Remove out of band data so doesn't get presented to user. 2862 * This can happen independent of advancing the URG pointer, 2863 * but if two URG's are pending at once, some out-of-band 2864 * data may creep in... ick. 2865 */ 2866 if (th->th_urp <= (u_int16_t) tlen 2867 #ifdef SO_OOBINLINE 2868 && (so->so_options & SO_OOBINLINE) == 0 2869 #endif 2870 ) 2871 tcp_pulloutofband(so, th, m, hdroptlen); 2872 } else 2873 /* 2874 * If no out of band data is expected, 2875 * pull receive urgent pointer along 2876 * with the receive window. 2877 */ 2878 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) 2879 tp->rcv_up = tp->rcv_nxt; 2880 dodata: /* XXX */ 2881 2882 /* 2883 * Process the segment text, merging it into the TCP sequencing queue, 2884 * and arranging for acknowledgement of receipt if necessary. 2885 * This process logically involves adjusting tp->rcv_wnd as data 2886 * is presented to the user (this happens in tcp_usrreq.c, 2887 * case PRU_RCVD). If a FIN has already been received on this 2888 * connection then we just ignore the text. 2889 */ 2890 if ((tlen || (tiflags & TH_FIN)) && 2891 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2892 /* 2893 * Insert segment ti into reassembly queue of tcp with 2894 * control block tp. Return TH_FIN if reassembly now includes 2895 * a segment with FIN. The macro form does the common case 2896 * inline (segment is the next to be received on an 2897 * established connection, and the queue is empty), 2898 * avoiding linkage into and removal from the queue and 2899 * repetition of various conversions. 2900 * Set DELACK for segments received in order, but ack 2901 * immediately when segments are out of order 2902 * (so fast retransmit can work). 2903 */ 2904 /* NOTE: this was TCP_REASS() macro, but used only once */ 2905 TCP_REASS_LOCK(tp); 2906 if (th->th_seq == tp->rcv_nxt && 2907 TAILQ_FIRST(&tp->segq) == NULL && 2908 tp->t_state == TCPS_ESTABLISHED) { 2909 tcp_setup_ack(tp, th); 2910 tp->rcv_nxt += tlen; 2911 tiflags = th->th_flags & TH_FIN; 2912 tcps = TCP_STAT_GETREF(); 2913 tcps[TCP_STAT_RCVPACK]++; 2914 tcps[TCP_STAT_RCVBYTE] += tlen; 2915 TCP_STAT_PUTREF(); 2916 nd6_hint(tp); 2917 if (so->so_state & SS_CANTRCVMORE) 2918 m_freem(m); 2919 else { 2920 m_adj(m, hdroptlen); 2921 sbappendstream(&(so)->so_rcv, m); 2922 } 2923 TCP_REASS_UNLOCK(tp); 2924 sorwakeup(so); 2925 } else { 2926 m_adj(m, hdroptlen); 2927 tiflags = tcp_reass(tp, th, m, &tlen); 2928 tp->t_flags |= TF_ACKNOW; 2929 TCP_REASS_UNLOCK(tp); 2930 } 2931 2932 /* 2933 * Note the amount of data that peer has sent into 2934 * our window, in order to estimate the sender's 2935 * buffer size. 2936 */ 2937 len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); 2938 } else { 2939 m_freem(m); 2940 m = NULL; 2941 tiflags &= ~TH_FIN; 2942 } 2943 2944 /* 2945 * If FIN is received ACK the FIN and let the user know 2946 * that the connection is closing. Ignore a FIN received before 2947 * the connection is fully established. 2948 */ 2949 if ((tiflags & TH_FIN) && TCPS_HAVEESTABLISHED(tp->t_state)) { 2950 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2951 socantrcvmore(so); 2952 tp->t_flags |= TF_ACKNOW; 2953 tp->rcv_nxt++; 2954 } 2955 switch (tp->t_state) { 2956 2957 /* 2958 * In ESTABLISHED STATE enter the CLOSE_WAIT state. 2959 */ 2960 case TCPS_ESTABLISHED: 2961 tp->t_state = TCPS_CLOSE_WAIT; 2962 break; 2963 2964 /* 2965 * If still in FIN_WAIT_1 STATE FIN has not been acked so 2966 * enter the CLOSING state. 2967 */ 2968 case TCPS_FIN_WAIT_1: 2969 tp->t_state = TCPS_CLOSING; 2970 break; 2971 2972 /* 2973 * In FIN_WAIT_2 state enter the TIME_WAIT state, 2974 * starting the time-wait timer, turning off the other 2975 * standard timers. 2976 */ 2977 case TCPS_FIN_WAIT_2: 2978 tp->t_state = TCPS_TIME_WAIT; 2979 tcp_canceltimers(tp); 2980 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * tp->t_msl); 2981 soisdisconnected(so); 2982 break; 2983 2984 /* 2985 * In TIME_WAIT state restart the 2 MSL time_wait timer. 2986 */ 2987 case TCPS_TIME_WAIT: 2988 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * tp->t_msl); 2989 break; 2990 } 2991 } 2992 #ifdef TCP_DEBUG 2993 if (so->so_options & SO_DEBUG) 2994 tcp_trace(TA_INPUT, ostate, tp, tcp_saveti, 0); 2995 #endif 2996 2997 /* 2998 * Return any desired output. 2999 */ 3000 if (needoutput || (tp->t_flags & TF_ACKNOW)) { 3001 KERNEL_LOCK(1, NULL); 3002 (void) tcp_output(tp); 3003 KERNEL_UNLOCK_ONE(NULL); 3004 } 3005 if (tcp_saveti) 3006 m_freem(tcp_saveti); 3007 3008 if (tp->t_state == TCPS_TIME_WAIT 3009 && (so->so_state & SS_NOFDREF) 3010 && (tp->t_inpcb || af != AF_INET) 3011 && (tp->t_in6pcb || af != AF_INET6) 3012 && ((af == AF_INET ? tcp4_vtw_enable : tcp6_vtw_enable) & 1) != 0 3013 && TAILQ_EMPTY(&tp->segq) 3014 && vtw_add(af, tp)) { 3015 ; 3016 } 3017 return; 3018 3019 badsyn: 3020 /* 3021 * Received a bad SYN. Increment counters and dropwithreset. 3022 */ 3023 TCP_STATINC(TCP_STAT_BADSYN); 3024 tp = NULL; 3025 goto dropwithreset; 3026 3027 dropafterack: 3028 /* 3029 * Generate an ACK dropping incoming segment if it occupies 3030 * sequence space, where the ACK reflects our state. 3031 */ 3032 if (tiflags & TH_RST) 3033 goto drop; 3034 goto dropafterack2; 3035 3036 dropafterack_ratelim: 3037 /* 3038 * We may want to rate-limit ACKs against SYN/RST attack. 3039 */ 3040 if (ppsratecheck(&tcp_ackdrop_ppslim_last, &tcp_ackdrop_ppslim_count, 3041 tcp_ackdrop_ppslim) == 0) { 3042 /* XXX stat */ 3043 goto drop; 3044 } 3045 /* ...fall into dropafterack2... */ 3046 3047 dropafterack2: 3048 m_freem(m); 3049 tp->t_flags |= TF_ACKNOW; 3050 KERNEL_LOCK(1, NULL); 3051 (void) tcp_output(tp); 3052 KERNEL_UNLOCK_ONE(NULL); 3053 if (tcp_saveti) 3054 m_freem(tcp_saveti); 3055 return; 3056 3057 dropwithreset_ratelim: 3058 /* 3059 * We may want to rate-limit RSTs in certain situations, 3060 * particularly if we are sending an RST in response to 3061 * an attempt to connect to or otherwise communicate with 3062 * a port for which we have no socket. 3063 */ 3064 if (ppsratecheck(&tcp_rst_ppslim_last, &tcp_rst_ppslim_count, 3065 tcp_rst_ppslim) == 0) { 3066 /* XXX stat */ 3067 goto drop; 3068 } 3069 /* ...fall into dropwithreset... */ 3070 3071 dropwithreset: 3072 /* 3073 * Generate a RST, dropping incoming segment. 3074 * Make ACK acceptable to originator of segment. 3075 */ 3076 if (tiflags & TH_RST) 3077 goto drop; 3078 3079 switch (af) { 3080 #ifdef INET6 3081 case AF_INET6: 3082 /* For following calls to tcp_respond */ 3083 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) 3084 goto drop; 3085 break; 3086 #endif /* INET6 */ 3087 case AF_INET: 3088 if (IN_MULTICAST(ip->ip_dst.s_addr) || 3089 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 3090 goto drop; 3091 } 3092 3093 if (tiflags & TH_ACK) 3094 (void)tcp_respond(tp, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 3095 else { 3096 if (tiflags & TH_SYN) 3097 tlen++; 3098 (void)tcp_respond(tp, m, m, th, th->th_seq + tlen, (tcp_seq)0, 3099 TH_RST|TH_ACK); 3100 } 3101 if (tcp_saveti) 3102 m_freem(tcp_saveti); 3103 return; 3104 3105 badcsum: 3106 drop: 3107 /* 3108 * Drop space held by incoming segment and return. 3109 */ 3110 if (tp) { 3111 if (tp->t_inpcb) 3112 so = tp->t_inpcb->inp_socket; 3113 #ifdef INET6 3114 else if (tp->t_in6pcb) 3115 so = tp->t_in6pcb->in6p_socket; 3116 #endif 3117 else 3118 so = NULL; 3119 #ifdef TCP_DEBUG 3120 if (so && (so->so_options & SO_DEBUG) != 0) 3121 tcp_trace(TA_DROP, ostate, tp, tcp_saveti, 0); 3122 #endif 3123 } 3124 if (tcp_saveti) 3125 m_freem(tcp_saveti); 3126 m_freem(m); 3127 return; 3128 } 3129 3130 #ifdef TCP_SIGNATURE 3131 int 3132 tcp_signature_apply(void *fstate, void *data, u_int len) 3133 { 3134 3135 MD5Update(fstate, (u_char *)data, len); 3136 return (0); 3137 } 3138 3139 struct secasvar * 3140 tcp_signature_getsav(struct mbuf *m, struct tcphdr *th) 3141 { 3142 struct secasvar *sav; 3143 #ifdef FAST_IPSEC 3144 union sockaddr_union dst; 3145 #endif 3146 struct ip *ip; 3147 struct ip6_hdr *ip6; 3148 3149 ip = mtod(m, struct ip *); 3150 switch (ip->ip_v) { 3151 case 4: 3152 ip = mtod(m, struct ip *); 3153 ip6 = NULL; 3154 break; 3155 case 6: 3156 ip = NULL; 3157 ip6 = mtod(m, struct ip6_hdr *); 3158 break; 3159 default: 3160 return (NULL); 3161 } 3162 3163 #ifdef FAST_IPSEC 3164 /* Extract the destination from the IP header in the mbuf. */ 3165 memset(&dst, 0, sizeof(union sockaddr_union)); 3166 if (ip !=NULL) { 3167 dst.sa.sa_len = sizeof(struct sockaddr_in); 3168 dst.sa.sa_family = AF_INET; 3169 dst.sin.sin_addr = ip->ip_dst; 3170 } else { 3171 dst.sa.sa_len = sizeof(struct sockaddr_in6); 3172 dst.sa.sa_family = AF_INET6; 3173 dst.sin6.sin6_addr = ip6->ip6_dst; 3174 } 3175 3176 /* 3177 * Look up an SADB entry which matches the address of the peer. 3178 */ 3179 sav = KEY_ALLOCSA(&dst, IPPROTO_TCP, htonl(TCP_SIG_SPI)); 3180 #else 3181 if (ip) 3182 sav = key_allocsa(AF_INET, (void *)&ip->ip_src, 3183 (void *)&ip->ip_dst, IPPROTO_TCP, 3184 htonl(TCP_SIG_SPI), 0, 0); 3185 else 3186 sav = key_allocsa(AF_INET6, (void *)&ip6->ip6_src, 3187 (void *)&ip6->ip6_dst, IPPROTO_TCP, 3188 htonl(TCP_SIG_SPI), 0, 0); 3189 #endif 3190 3191 return (sav); /* freesav must be performed by caller */ 3192 } 3193 3194 int 3195 tcp_signature(struct mbuf *m, struct tcphdr *th, int thoff, 3196 struct secasvar *sav, char *sig) 3197 { 3198 MD5_CTX ctx; 3199 struct ip *ip; 3200 struct ipovly *ipovly; 3201 struct ip6_hdr *ip6; 3202 struct ippseudo ippseudo; 3203 struct ip6_hdr_pseudo ip6pseudo; 3204 struct tcphdr th0; 3205 int l, tcphdrlen; 3206 3207 if (sav == NULL) 3208 return (-1); 3209 3210 tcphdrlen = th->th_off * 4; 3211 3212 switch (mtod(m, struct ip *)->ip_v) { 3213 case 4: 3214 ip = mtod(m, struct ip *); 3215 ip6 = NULL; 3216 break; 3217 case 6: 3218 ip = NULL; 3219 ip6 = mtod(m, struct ip6_hdr *); 3220 break; 3221 default: 3222 return (-1); 3223 } 3224 3225 MD5Init(&ctx); 3226 3227 if (ip) { 3228 memset(&ippseudo, 0, sizeof(ippseudo)); 3229 ipovly = (struct ipovly *)ip; 3230 ippseudo.ippseudo_src = ipovly->ih_src; 3231 ippseudo.ippseudo_dst = ipovly->ih_dst; 3232 ippseudo.ippseudo_pad = 0; 3233 ippseudo.ippseudo_p = IPPROTO_TCP; 3234 ippseudo.ippseudo_len = htons(m->m_pkthdr.len - thoff); 3235 MD5Update(&ctx, (char *)&ippseudo, sizeof(ippseudo)); 3236 } else { 3237 memset(&ip6pseudo, 0, sizeof(ip6pseudo)); 3238 ip6pseudo.ip6ph_src = ip6->ip6_src; 3239 in6_clearscope(&ip6pseudo.ip6ph_src); 3240 ip6pseudo.ip6ph_dst = ip6->ip6_dst; 3241 in6_clearscope(&ip6pseudo.ip6ph_dst); 3242 ip6pseudo.ip6ph_len = htons(m->m_pkthdr.len - thoff); 3243 ip6pseudo.ip6ph_nxt = IPPROTO_TCP; 3244 MD5Update(&ctx, (char *)&ip6pseudo, sizeof(ip6pseudo)); 3245 } 3246 3247 th0 = *th; 3248 th0.th_sum = 0; 3249 MD5Update(&ctx, (char *)&th0, sizeof(th0)); 3250 3251 l = m->m_pkthdr.len - thoff - tcphdrlen; 3252 if (l > 0) 3253 m_apply(m, thoff + tcphdrlen, 3254 m->m_pkthdr.len - thoff - tcphdrlen, 3255 tcp_signature_apply, &ctx); 3256 3257 MD5Update(&ctx, _KEYBUF(sav->key_auth), _KEYLEN(sav->key_auth)); 3258 MD5Final(sig, &ctx); 3259 3260 return (0); 3261 } 3262 #endif 3263 3264 /* 3265 * tcp_dooptions: parse and process tcp options. 3266 * 3267 * returns -1 if this segment should be dropped. (eg. wrong signature) 3268 * otherwise returns 0. 3269 */ 3270 3271 static int 3272 tcp_dooptions(struct tcpcb *tp, const u_char *cp, int cnt, 3273 struct tcphdr *th, 3274 struct mbuf *m, int toff, struct tcp_opt_info *oi) 3275 { 3276 u_int16_t mss; 3277 int opt, optlen = 0; 3278 #ifdef TCP_SIGNATURE 3279 void *sigp = NULL; 3280 char sigbuf[TCP_SIGLEN]; 3281 struct secasvar *sav = NULL; 3282 #endif 3283 3284 for (; cp && cnt > 0; cnt -= optlen, cp += optlen) { 3285 opt = cp[0]; 3286 if (opt == TCPOPT_EOL) 3287 break; 3288 if (opt == TCPOPT_NOP) 3289 optlen = 1; 3290 else { 3291 if (cnt < 2) 3292 break; 3293 optlen = cp[1]; 3294 if (optlen < 2 || optlen > cnt) 3295 break; 3296 } 3297 switch (opt) { 3298 3299 default: 3300 continue; 3301 3302 case TCPOPT_MAXSEG: 3303 if (optlen != TCPOLEN_MAXSEG) 3304 continue; 3305 if (!(th->th_flags & TH_SYN)) 3306 continue; 3307 if (TCPS_HAVERCVDSYN(tp->t_state)) 3308 continue; 3309 bcopy(cp + 2, &mss, sizeof(mss)); 3310 oi->maxseg = ntohs(mss); 3311 break; 3312 3313 case TCPOPT_WINDOW: 3314 if (optlen != TCPOLEN_WINDOW) 3315 continue; 3316 if (!(th->th_flags & TH_SYN)) 3317 continue; 3318 if (TCPS_HAVERCVDSYN(tp->t_state)) 3319 continue; 3320 tp->t_flags |= TF_RCVD_SCALE; 3321 tp->requested_s_scale = cp[2]; 3322 if (tp->requested_s_scale > TCP_MAX_WINSHIFT) { 3323 #if 0 /*XXX*/ 3324 char *p; 3325 3326 if (ip) 3327 p = ntohl(ip->ip_src); 3328 #ifdef INET6 3329 else if (ip6) 3330 p = ip6_sprintf(&ip6->ip6_src); 3331 #endif 3332 else 3333 p = "(unknown)"; 3334 log(LOG_ERR, "TCP: invalid wscale %d from %s, " 3335 "assuming %d\n", 3336 tp->requested_s_scale, p, 3337 TCP_MAX_WINSHIFT); 3338 #else 3339 log(LOG_ERR, "TCP: invalid wscale %d, " 3340 "assuming %d\n", 3341 tp->requested_s_scale, 3342 TCP_MAX_WINSHIFT); 3343 #endif 3344 tp->requested_s_scale = TCP_MAX_WINSHIFT; 3345 } 3346 break; 3347 3348 case TCPOPT_TIMESTAMP: 3349 if (optlen != TCPOLEN_TIMESTAMP) 3350 continue; 3351 oi->ts_present = 1; 3352 bcopy(cp + 2, &oi->ts_val, sizeof(oi->ts_val)); 3353 NTOHL(oi->ts_val); 3354 bcopy(cp + 6, &oi->ts_ecr, sizeof(oi->ts_ecr)); 3355 NTOHL(oi->ts_ecr); 3356 3357 if (!(th->th_flags & TH_SYN)) 3358 continue; 3359 if (TCPS_HAVERCVDSYN(tp->t_state)) 3360 continue; 3361 /* 3362 * A timestamp received in a SYN makes 3363 * it ok to send timestamp requests and replies. 3364 */ 3365 tp->t_flags |= TF_RCVD_TSTMP; 3366 tp->ts_recent = oi->ts_val; 3367 tp->ts_recent_age = tcp_now; 3368 break; 3369 3370 case TCPOPT_SACK_PERMITTED: 3371 if (optlen != TCPOLEN_SACK_PERMITTED) 3372 continue; 3373 if (!(th->th_flags & TH_SYN)) 3374 continue; 3375 if (TCPS_HAVERCVDSYN(tp->t_state)) 3376 continue; 3377 if (tcp_do_sack) { 3378 tp->t_flags |= TF_SACK_PERMIT; 3379 tp->t_flags |= TF_WILL_SACK; 3380 } 3381 break; 3382 3383 case TCPOPT_SACK: 3384 tcp_sack_option(tp, th, cp, optlen); 3385 break; 3386 #ifdef TCP_SIGNATURE 3387 case TCPOPT_SIGNATURE: 3388 if (optlen != TCPOLEN_SIGNATURE) 3389 continue; 3390 if (sigp && memcmp(sigp, cp + 2, TCP_SIGLEN)) 3391 return (-1); 3392 3393 sigp = sigbuf; 3394 memcpy(sigbuf, cp + 2, TCP_SIGLEN); 3395 tp->t_flags |= TF_SIGNATURE; 3396 break; 3397 #endif 3398 } 3399 } 3400 3401 #ifdef TCP_SIGNATURE 3402 if (tp->t_flags & TF_SIGNATURE) { 3403 3404 sav = tcp_signature_getsav(m, th); 3405 3406 if (sav == NULL && tp->t_state == TCPS_LISTEN) 3407 return (-1); 3408 } 3409 3410 if ((sigp ? TF_SIGNATURE : 0) ^ (tp->t_flags & TF_SIGNATURE)) { 3411 if (sav == NULL) 3412 return (-1); 3413 #ifdef FAST_IPSEC 3414 KEY_FREESAV(&sav); 3415 #else 3416 key_freesav(sav); 3417 #endif 3418 return (-1); 3419 } 3420 3421 if (sigp) { 3422 char sig[TCP_SIGLEN]; 3423 3424 tcp_fields_to_net(th); 3425 if (tcp_signature(m, th, toff, sav, sig) < 0) { 3426 tcp_fields_to_host(th); 3427 if (sav == NULL) 3428 return (-1); 3429 #ifdef FAST_IPSEC 3430 KEY_FREESAV(&sav); 3431 #else 3432 key_freesav(sav); 3433 #endif 3434 return (-1); 3435 } 3436 tcp_fields_to_host(th); 3437 3438 if (memcmp(sig, sigp, TCP_SIGLEN)) { 3439 TCP_STATINC(TCP_STAT_BADSIG); 3440 if (sav == NULL) 3441 return (-1); 3442 #ifdef FAST_IPSEC 3443 KEY_FREESAV(&sav); 3444 #else 3445 key_freesav(sav); 3446 #endif 3447 return (-1); 3448 } else 3449 TCP_STATINC(TCP_STAT_GOODSIG); 3450 3451 key_sa_recordxfer(sav, m); 3452 #ifdef FAST_IPSEC 3453 KEY_FREESAV(&sav); 3454 #else 3455 key_freesav(sav); 3456 #endif 3457 } 3458 #endif 3459 3460 return (0); 3461 } 3462 3463 /* 3464 * Pull out of band byte out of a segment so 3465 * it doesn't appear in the user's data queue. 3466 * It is still reflected in the segment length for 3467 * sequencing purposes. 3468 */ 3469 void 3470 tcp_pulloutofband(struct socket *so, struct tcphdr *th, 3471 struct mbuf *m, int off) 3472 { 3473 int cnt = off + th->th_urp - 1; 3474 3475 while (cnt >= 0) { 3476 if (m->m_len > cnt) { 3477 char *cp = mtod(m, char *) + cnt; 3478 struct tcpcb *tp = sototcpcb(so); 3479 3480 tp->t_iobc = *cp; 3481 tp->t_oobflags |= TCPOOB_HAVEDATA; 3482 bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); 3483 m->m_len--; 3484 return; 3485 } 3486 cnt -= m->m_len; 3487 m = m->m_next; 3488 if (m == 0) 3489 break; 3490 } 3491 panic("tcp_pulloutofband"); 3492 } 3493 3494 /* 3495 * Collect new round-trip time estimate 3496 * and update averages and current timeout. 3497 * 3498 * rtt is in units of slow ticks (typically 500 ms) -- essentially the 3499 * difference of two timestamps. 3500 */ 3501 void 3502 tcp_xmit_timer(struct tcpcb *tp, uint32_t rtt) 3503 { 3504 int32_t delta; 3505 3506 TCP_STATINC(TCP_STAT_RTTUPDATED); 3507 if (tp->t_srtt != 0) { 3508 /* 3509 * Compute the amount to add to srtt for smoothing, 3510 * *alpha, or 2^(-TCP_RTT_SHIFT). Because 3511 * srtt is stored in 1/32 slow ticks, we conceptually 3512 * shift left 5 bits, subtract srtt to get the 3513 * diference, and then shift right by TCP_RTT_SHIFT 3514 * (3) to obtain 1/8 of the difference. 3515 */ 3516 delta = (rtt << 2) - (tp->t_srtt >> TCP_RTT_SHIFT); 3517 /* 3518 * This can never happen, because delta's lowest 3519 * possible value is 1/8 of t_srtt. But if it does, 3520 * set srtt to some reasonable value, here chosen 3521 * as 1/8 tick. 3522 */ 3523 if ((tp->t_srtt += delta) <= 0) 3524 tp->t_srtt = 1 << 2; 3525 /* 3526 * RFC2988 requires that rttvar be updated first. 3527 * This code is compliant because "delta" is the old 3528 * srtt minus the new observation (scaled). 3529 * 3530 * RFC2988 says: 3531 * rttvar = (1-beta) * rttvar + beta * |srtt-observed| 3532 * 3533 * delta is in units of 1/32 ticks, and has then been 3534 * divided by 8. This is equivalent to being in 1/16s 3535 * units and divided by 4. Subtract from it 1/4 of 3536 * the existing rttvar to form the (signed) amount to 3537 * adjust. 3538 */ 3539 if (delta < 0) 3540 delta = -delta; 3541 delta -= (tp->t_rttvar >> TCP_RTTVAR_SHIFT); 3542 /* 3543 * As with srtt, this should never happen. There is 3544 * no support in RFC2988 for this operation. But 1/4s 3545 * as rttvar when faced with something arguably wrong 3546 * is ok. 3547 */ 3548 if ((tp->t_rttvar += delta) <= 0) 3549 tp->t_rttvar = 1 << 2; 3550 3551 /* 3552 * If srtt exceeds .01 second, ensure we use the 'remote' MSL 3553 * Problem is: it doesn't work. Disabled by defaulting 3554 * tcp_rttlocal to 0; see corresponding code in 3555 * tcp_subr that selects local vs remote in a different way. 3556 * 3557 * The static branch prediction hint here should be removed 3558 * when the rtt estimator is fixed and the rtt_enable code 3559 * is turned back on. 3560 */ 3561 if (__predict_false(tcp_rttlocal) && tcp_msl_enable 3562 && tp->t_srtt > tcp_msl_remote_threshold 3563 && tp->t_msl < tcp_msl_remote) { 3564 tp->t_msl = tcp_msl_remote; 3565 } 3566 } else { 3567 /* 3568 * This is the first measurement. Per RFC2988, 2.2, 3569 * set rtt=R and srtt=R/2. 3570 * For srtt, storage representation is 1/32 ticks, 3571 * so shift left by 5. 3572 * For rttvar, storage representation is 1/16 ticks, 3573 * So shift left by 4, but then right by 1 to halve. 3574 */ 3575 tp->t_srtt = rtt << (TCP_RTT_SHIFT + 2); 3576 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT + 2 - 1); 3577 } 3578 tp->t_rtttime = 0; 3579 tp->t_rxtshift = 0; 3580 3581 /* 3582 * the retransmit should happen at rtt + 4 * rttvar. 3583 * Because of the way we do the smoothing, srtt and rttvar 3584 * will each average +1/2 tick of bias. When we compute 3585 * the retransmit timer, we want 1/2 tick of rounding and 3586 * 1 extra tick because of +-1/2 tick uncertainty in the 3587 * firing of the timer. The bias will give us exactly the 3588 * 1.5 tick we need. But, because the bias is 3589 * statistical, we have to test that we don't drop below 3590 * the minimum feasible timer (which is 2 ticks). 3591 */ 3592 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), 3593 max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX); 3594 3595 /* 3596 * We received an ack for a packet that wasn't retransmitted; 3597 * it is probably safe to discard any error indications we've 3598 * received recently. This isn't quite right, but close enough 3599 * for now (a route might have failed after we sent a segment, 3600 * and the return path might not be symmetrical). 3601 */ 3602 tp->t_softerror = 0; 3603 } 3604 3605 3606 /* 3607 * TCP compressed state engine. Currently used to hold compressed 3608 * state for SYN_RECEIVED. 3609 */ 3610 3611 u_long syn_cache_count; 3612 u_int32_t syn_hash1, syn_hash2; 3613 3614 #define SYN_HASH(sa, sp, dp) \ 3615 ((((sa)->s_addr^syn_hash1)*(((((u_int32_t)(dp))<<16) + \ 3616 ((u_int32_t)(sp)))^syn_hash2))) 3617 #ifndef INET6 3618 #define SYN_HASHALL(hash, src, dst) \ 3619 do { \ 3620 hash = SYN_HASH(&((const struct sockaddr_in *)(src))->sin_addr, \ 3621 ((const struct sockaddr_in *)(src))->sin_port, \ 3622 ((const struct sockaddr_in *)(dst))->sin_port); \ 3623 } while (/*CONSTCOND*/ 0) 3624 #else 3625 #define SYN_HASH6(sa, sp, dp) \ 3626 ((((sa)->s6_addr32[0] ^ (sa)->s6_addr32[3] ^ syn_hash1) * \ 3627 (((((u_int32_t)(dp))<<16) + ((u_int32_t)(sp)))^syn_hash2)) \ 3628 & 0x7fffffff) 3629 3630 #define SYN_HASHALL(hash, src, dst) \ 3631 do { \ 3632 switch ((src)->sa_family) { \ 3633 case AF_INET: \ 3634 hash = SYN_HASH(&((const struct sockaddr_in *)(src))->sin_addr, \ 3635 ((const struct sockaddr_in *)(src))->sin_port, \ 3636 ((const struct sockaddr_in *)(dst))->sin_port); \ 3637 break; \ 3638 case AF_INET6: \ 3639 hash = SYN_HASH6(&((const struct sockaddr_in6 *)(src))->sin6_addr, \ 3640 ((const struct sockaddr_in6 *)(src))->sin6_port, \ 3641 ((const struct sockaddr_in6 *)(dst))->sin6_port); \ 3642 break; \ 3643 default: \ 3644 hash = 0; \ 3645 } \ 3646 } while (/*CONSTCOND*/0) 3647 #endif /* INET6 */ 3648 3649 static struct pool syn_cache_pool; 3650 3651 /* 3652 * We don't estimate RTT with SYNs, so each packet starts with the default 3653 * RTT and each timer step has a fixed timeout value. 3654 */ 3655 #define SYN_CACHE_TIMER_ARM(sc) \ 3656 do { \ 3657 TCPT_RANGESET((sc)->sc_rxtcur, \ 3658 TCPTV_SRTTDFLT * tcp_backoff[(sc)->sc_rxtshift], TCPTV_MIN, \ 3659 TCPTV_REXMTMAX); \ 3660 callout_reset(&(sc)->sc_timer, \ 3661 (sc)->sc_rxtcur * (hz / PR_SLOWHZ), syn_cache_timer, (sc)); \ 3662 } while (/*CONSTCOND*/0) 3663 3664 #define SYN_CACHE_TIMESTAMP(sc) (tcp_now - (sc)->sc_timebase) 3665 3666 static inline void 3667 syn_cache_rm(struct syn_cache *sc) 3668 { 3669 TAILQ_REMOVE(&tcp_syn_cache[sc->sc_bucketidx].sch_bucket, 3670 sc, sc_bucketq); 3671 sc->sc_tp = NULL; 3672 LIST_REMOVE(sc, sc_tpq); 3673 tcp_syn_cache[sc->sc_bucketidx].sch_length--; 3674 callout_stop(&sc->sc_timer); 3675 syn_cache_count--; 3676 } 3677 3678 static inline void 3679 syn_cache_put(struct syn_cache *sc) 3680 { 3681 if (sc->sc_ipopts) 3682 (void) m_free(sc->sc_ipopts); 3683 rtcache_free(&sc->sc_route); 3684 sc->sc_flags |= SCF_DEAD; 3685 if (!callout_invoking(&sc->sc_timer)) 3686 callout_schedule(&(sc)->sc_timer, 1); 3687 } 3688 3689 void 3690 syn_cache_init(void) 3691 { 3692 int i; 3693 3694 pool_init(&syn_cache_pool, sizeof(struct syn_cache), 0, 0, 0, 3695 "synpl", NULL, IPL_SOFTNET); 3696 3697 /* Initialize the hash buckets. */ 3698 for (i = 0; i < tcp_syn_cache_size; i++) 3699 TAILQ_INIT(&tcp_syn_cache[i].sch_bucket); 3700 } 3701 3702 void 3703 syn_cache_insert(struct syn_cache *sc, struct tcpcb *tp) 3704 { 3705 struct syn_cache_head *scp; 3706 struct syn_cache *sc2; 3707 int s; 3708 3709 /* 3710 * If there are no entries in the hash table, reinitialize 3711 * the hash secrets. 3712 */ 3713 if (syn_cache_count == 0) { 3714 syn_hash1 = arc4random(); 3715 syn_hash2 = arc4random(); 3716 } 3717 3718 SYN_HASHALL(sc->sc_hash, &sc->sc_src.sa, &sc->sc_dst.sa); 3719 sc->sc_bucketidx = sc->sc_hash % tcp_syn_cache_size; 3720 scp = &tcp_syn_cache[sc->sc_bucketidx]; 3721 3722 /* 3723 * Make sure that we don't overflow the per-bucket 3724 * limit or the total cache size limit. 3725 */ 3726 s = splsoftnet(); 3727 if (scp->sch_length >= tcp_syn_bucket_limit) { 3728 TCP_STATINC(TCP_STAT_SC_BUCKETOVERFLOW); 3729 /* 3730 * The bucket is full. Toss the oldest element in the 3731 * bucket. This will be the first entry in the bucket. 3732 */ 3733 sc2 = TAILQ_FIRST(&scp->sch_bucket); 3734 #ifdef DIAGNOSTIC 3735 /* 3736 * This should never happen; we should always find an 3737 * entry in our bucket. 3738 */ 3739 if (sc2 == NULL) 3740 panic("syn_cache_insert: bucketoverflow: impossible"); 3741 #endif 3742 syn_cache_rm(sc2); 3743 syn_cache_put(sc2); /* calls pool_put but see spl above */ 3744 } else if (syn_cache_count >= tcp_syn_cache_limit) { 3745 struct syn_cache_head *scp2, *sce; 3746 3747 TCP_STATINC(TCP_STAT_SC_OVERFLOWED); 3748 /* 3749 * The cache is full. Toss the oldest entry in the 3750 * first non-empty bucket we can find. 3751 * 3752 * XXX We would really like to toss the oldest 3753 * entry in the cache, but we hope that this 3754 * condition doesn't happen very often. 3755 */ 3756 scp2 = scp; 3757 if (TAILQ_EMPTY(&scp2->sch_bucket)) { 3758 sce = &tcp_syn_cache[tcp_syn_cache_size]; 3759 for (++scp2; scp2 != scp; scp2++) { 3760 if (scp2 >= sce) 3761 scp2 = &tcp_syn_cache[0]; 3762 if (! TAILQ_EMPTY(&scp2->sch_bucket)) 3763 break; 3764 } 3765 #ifdef DIAGNOSTIC 3766 /* 3767 * This should never happen; we should always find a 3768 * non-empty bucket. 3769 */ 3770 if (scp2 == scp) 3771 panic("syn_cache_insert: cacheoverflow: " 3772 "impossible"); 3773 #endif 3774 } 3775 sc2 = TAILQ_FIRST(&scp2->sch_bucket); 3776 syn_cache_rm(sc2); 3777 syn_cache_put(sc2); /* calls pool_put but see spl above */ 3778 } 3779 3780 /* 3781 * Initialize the entry's timer. 3782 */ 3783 sc->sc_rxttot = 0; 3784 sc->sc_rxtshift = 0; 3785 SYN_CACHE_TIMER_ARM(sc); 3786 3787 /* Link it from tcpcb entry */ 3788 LIST_INSERT_HEAD(&tp->t_sc, sc, sc_tpq); 3789 3790 /* Put it into the bucket. */ 3791 TAILQ_INSERT_TAIL(&scp->sch_bucket, sc, sc_bucketq); 3792 scp->sch_length++; 3793 syn_cache_count++; 3794 3795 TCP_STATINC(TCP_STAT_SC_ADDED); 3796 splx(s); 3797 } 3798 3799 /* 3800 * Walk the timer queues, looking for SYN,ACKs that need to be retransmitted. 3801 * If we have retransmitted an entry the maximum number of times, expire 3802 * that entry. 3803 */ 3804 void 3805 syn_cache_timer(void *arg) 3806 { 3807 struct syn_cache *sc = arg; 3808 3809 mutex_enter(softnet_lock); 3810 KERNEL_LOCK(1, NULL); 3811 callout_ack(&sc->sc_timer); 3812 3813 if (__predict_false(sc->sc_flags & SCF_DEAD)) { 3814 TCP_STATINC(TCP_STAT_SC_DELAYED_FREE); 3815 callout_destroy(&sc->sc_timer); 3816 pool_put(&syn_cache_pool, sc); 3817 KERNEL_UNLOCK_ONE(NULL); 3818 mutex_exit(softnet_lock); 3819 return; 3820 } 3821 3822 if (__predict_false(sc->sc_rxtshift == TCP_MAXRXTSHIFT)) { 3823 /* Drop it -- too many retransmissions. */ 3824 goto dropit; 3825 } 3826 3827 /* 3828 * Compute the total amount of time this entry has 3829 * been on a queue. If this entry has been on longer 3830 * than the keep alive timer would allow, expire it. 3831 */ 3832 sc->sc_rxttot += sc->sc_rxtcur; 3833 if (sc->sc_rxttot >= tcp_keepinit) 3834 goto dropit; 3835 3836 TCP_STATINC(TCP_STAT_SC_RETRANSMITTED); 3837 (void) syn_cache_respond(sc, NULL); 3838 3839 /* Advance the timer back-off. */ 3840 sc->sc_rxtshift++; 3841 SYN_CACHE_TIMER_ARM(sc); 3842 3843 KERNEL_UNLOCK_ONE(NULL); 3844 mutex_exit(softnet_lock); 3845 return; 3846 3847 dropit: 3848 TCP_STATINC(TCP_STAT_SC_TIMED_OUT); 3849 syn_cache_rm(sc); 3850 if (sc->sc_ipopts) 3851 (void) m_free(sc->sc_ipopts); 3852 rtcache_free(&sc->sc_route); 3853 callout_destroy(&sc->sc_timer); 3854 pool_put(&syn_cache_pool, sc); 3855 KERNEL_UNLOCK_ONE(NULL); 3856 mutex_exit(softnet_lock); 3857 } 3858 3859 /* 3860 * Remove syn cache created by the specified tcb entry, 3861 * because this does not make sense to keep them 3862 * (if there's no tcb entry, syn cache entry will never be used) 3863 */ 3864 void 3865 syn_cache_cleanup(struct tcpcb *tp) 3866 { 3867 struct syn_cache *sc, *nsc; 3868 int s; 3869 3870 s = splsoftnet(); 3871 3872 for (sc = LIST_FIRST(&tp->t_sc); sc != NULL; sc = nsc) { 3873 nsc = LIST_NEXT(sc, sc_tpq); 3874 3875 #ifdef DIAGNOSTIC 3876 if (sc->sc_tp != tp) 3877 panic("invalid sc_tp in syn_cache_cleanup"); 3878 #endif 3879 syn_cache_rm(sc); 3880 syn_cache_put(sc); /* calls pool_put but see spl above */ 3881 } 3882 /* just for safety */ 3883 LIST_INIT(&tp->t_sc); 3884 3885 splx(s); 3886 } 3887 3888 /* 3889 * Find an entry in the syn cache. 3890 */ 3891 struct syn_cache * 3892 syn_cache_lookup(const struct sockaddr *src, const struct sockaddr *dst, 3893 struct syn_cache_head **headp) 3894 { 3895 struct syn_cache *sc; 3896 struct syn_cache_head *scp; 3897 u_int32_t hash; 3898 int s; 3899 3900 SYN_HASHALL(hash, src, dst); 3901 3902 scp = &tcp_syn_cache[hash % tcp_syn_cache_size]; 3903 *headp = scp; 3904 s = splsoftnet(); 3905 for (sc = TAILQ_FIRST(&scp->sch_bucket); sc != NULL; 3906 sc = TAILQ_NEXT(sc, sc_bucketq)) { 3907 if (sc->sc_hash != hash) 3908 continue; 3909 if (!memcmp(&sc->sc_src, src, src->sa_len) && 3910 !memcmp(&sc->sc_dst, dst, dst->sa_len)) { 3911 splx(s); 3912 return (sc); 3913 } 3914 } 3915 splx(s); 3916 return (NULL); 3917 } 3918 3919 /* 3920 * This function gets called when we receive an ACK for a 3921 * socket in the LISTEN state. We look up the connection 3922 * in the syn cache, and if its there, we pull it out of 3923 * the cache and turn it into a full-blown connection in 3924 * the SYN-RECEIVED state. 3925 * 3926 * The return values may not be immediately obvious, and their effects 3927 * can be subtle, so here they are: 3928 * 3929 * NULL SYN was not found in cache; caller should drop the 3930 * packet and send an RST. 3931 * 3932 * -1 We were unable to create the new connection, and are 3933 * aborting it. An ACK,RST is being sent to the peer 3934 * (unless we got screwey sequence numbners; see below), 3935 * because the 3-way handshake has been completed. Caller 3936 * should not free the mbuf, since we may be using it. If 3937 * we are not, we will free it. 3938 * 3939 * Otherwise, the return value is a pointer to the new socket 3940 * associated with the connection. 3941 */ 3942 struct socket * 3943 syn_cache_get(struct sockaddr *src, struct sockaddr *dst, 3944 struct tcphdr *th, unsigned int hlen, unsigned int tlen, 3945 struct socket *so, struct mbuf *m) 3946 { 3947 struct syn_cache *sc; 3948 struct syn_cache_head *scp; 3949 struct inpcb *inp = NULL; 3950 #ifdef INET6 3951 struct in6pcb *in6p = NULL; 3952 #endif 3953 struct tcpcb *tp = 0; 3954 struct mbuf *am; 3955 int s; 3956 struct socket *oso; 3957 3958 s = splsoftnet(); 3959 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 3960 splx(s); 3961 return (NULL); 3962 } 3963 3964 /* 3965 * Verify the sequence and ack numbers. Try getting the correct 3966 * response again. 3967 */ 3968 if ((th->th_ack != sc->sc_iss + 1) || 3969 SEQ_LEQ(th->th_seq, sc->sc_irs) || 3970 SEQ_GT(th->th_seq, sc->sc_irs + 1 + sc->sc_win)) { 3971 (void) syn_cache_respond(sc, m); 3972 splx(s); 3973 return ((struct socket *)(-1)); 3974 } 3975 3976 /* Remove this cache entry */ 3977 syn_cache_rm(sc); 3978 splx(s); 3979 3980 /* 3981 * Ok, create the full blown connection, and set things up 3982 * as they would have been set up if we had created the 3983 * connection when the SYN arrived. If we can't create 3984 * the connection, abort it. 3985 */ 3986 /* 3987 * inp still has the OLD in_pcb stuff, set the 3988 * v6-related flags on the new guy, too. This is 3989 * done particularly for the case where an AF_INET6 3990 * socket is bound only to a port, and a v4 connection 3991 * comes in on that port. 3992 * we also copy the flowinfo from the original pcb 3993 * to the new one. 3994 */ 3995 oso = so; 3996 so = sonewconn(so, SS_ISCONNECTED); 3997 if (so == NULL) 3998 goto resetandabort; 3999 4000 switch (so->so_proto->pr_domain->dom_family) { 4001 #ifdef INET 4002 case AF_INET: 4003 inp = sotoinpcb(so); 4004 break; 4005 #endif 4006 #ifdef INET6 4007 case AF_INET6: 4008 in6p = sotoin6pcb(so); 4009 break; 4010 #endif 4011 } 4012 switch (src->sa_family) { 4013 #ifdef INET 4014 case AF_INET: 4015 if (inp) { 4016 inp->inp_laddr = ((struct sockaddr_in *)dst)->sin_addr; 4017 inp->inp_lport = ((struct sockaddr_in *)dst)->sin_port; 4018 inp->inp_options = ip_srcroute(); 4019 in_pcbstate(inp, INP_BOUND); 4020 if (inp->inp_options == NULL) { 4021 inp->inp_options = sc->sc_ipopts; 4022 sc->sc_ipopts = NULL; 4023 } 4024 } 4025 #ifdef INET6 4026 else if (in6p) { 4027 /* IPv4 packet to AF_INET6 socket */ 4028 memset(&in6p->in6p_laddr, 0, sizeof(in6p->in6p_laddr)); 4029 in6p->in6p_laddr.s6_addr16[5] = htons(0xffff); 4030 bcopy(&((struct sockaddr_in *)dst)->sin_addr, 4031 &in6p->in6p_laddr.s6_addr32[3], 4032 sizeof(((struct sockaddr_in *)dst)->sin_addr)); 4033 in6p->in6p_lport = ((struct sockaddr_in *)dst)->sin_port; 4034 in6totcpcb(in6p)->t_family = AF_INET; 4035 if (sotoin6pcb(oso)->in6p_flags & IN6P_IPV6_V6ONLY) 4036 in6p->in6p_flags |= IN6P_IPV6_V6ONLY; 4037 else 4038 in6p->in6p_flags &= ~IN6P_IPV6_V6ONLY; 4039 in6_pcbstate(in6p, IN6P_BOUND); 4040 } 4041 #endif 4042 break; 4043 #endif 4044 #ifdef INET6 4045 case AF_INET6: 4046 if (in6p) { 4047 in6p->in6p_laddr = ((struct sockaddr_in6 *)dst)->sin6_addr; 4048 in6p->in6p_lport = ((struct sockaddr_in6 *)dst)->sin6_port; 4049 in6_pcbstate(in6p, IN6P_BOUND); 4050 } 4051 break; 4052 #endif 4053 } 4054 #ifdef INET6 4055 if (in6p && in6totcpcb(in6p)->t_family == AF_INET6 && sotoinpcb(oso)) { 4056 struct in6pcb *oin6p = sotoin6pcb(oso); 4057 /* inherit socket options from the listening socket */ 4058 in6p->in6p_flags |= (oin6p->in6p_flags & IN6P_CONTROLOPTS); 4059 if (in6p->in6p_flags & IN6P_CONTROLOPTS) { 4060 m_freem(in6p->in6p_options); 4061 in6p->in6p_options = 0; 4062 } 4063 ip6_savecontrol(in6p, &in6p->in6p_options, 4064 mtod(m, struct ip6_hdr *), m); 4065 } 4066 #endif 4067 4068 #if defined(IPSEC) || defined(FAST_IPSEC) 4069 /* 4070 * we make a copy of policy, instead of sharing the policy, 4071 * for better behavior in terms of SA lookup and dead SA removal. 4072 */ 4073 if (inp) { 4074 /* copy old policy into new socket's */ 4075 if (ipsec_copy_pcbpolicy(sotoinpcb(oso)->inp_sp, inp->inp_sp)) 4076 printf("tcp_input: could not copy policy\n"); 4077 } 4078 #ifdef INET6 4079 else if (in6p) { 4080 /* copy old policy into new socket's */ 4081 if (ipsec_copy_pcbpolicy(sotoin6pcb(oso)->in6p_sp, 4082 in6p->in6p_sp)) 4083 printf("tcp_input: could not copy policy\n"); 4084 } 4085 #endif 4086 #endif 4087 4088 /* 4089 * Give the new socket our cached route reference. 4090 */ 4091 if (inp) { 4092 rtcache_copy(&inp->inp_route, &sc->sc_route); 4093 rtcache_free(&sc->sc_route); 4094 } 4095 #ifdef INET6 4096 else { 4097 rtcache_copy(&in6p->in6p_route, &sc->sc_route); 4098 rtcache_free(&sc->sc_route); 4099 } 4100 #endif 4101 4102 am = m_get(M_DONTWAIT, MT_SONAME); /* XXX */ 4103 if (am == NULL) 4104 goto resetandabort; 4105 MCLAIM(am, &tcp_mowner); 4106 am->m_len = src->sa_len; 4107 bcopy(src, mtod(am, void *), src->sa_len); 4108 if (inp) { 4109 if (in_pcbconnect(inp, am, &lwp0)) { 4110 (void) m_free(am); 4111 goto resetandabort; 4112 } 4113 } 4114 #ifdef INET6 4115 else if (in6p) { 4116 if (src->sa_family == AF_INET) { 4117 /* IPv4 packet to AF_INET6 socket */ 4118 struct sockaddr_in6 *sin6; 4119 sin6 = mtod(am, struct sockaddr_in6 *); 4120 am->m_len = sizeof(*sin6); 4121 memset(sin6, 0, sizeof(*sin6)); 4122 sin6->sin6_family = AF_INET6; 4123 sin6->sin6_len = sizeof(*sin6); 4124 sin6->sin6_port = ((struct sockaddr_in *)src)->sin_port; 4125 sin6->sin6_addr.s6_addr16[5] = htons(0xffff); 4126 bcopy(&((struct sockaddr_in *)src)->sin_addr, 4127 &sin6->sin6_addr.s6_addr32[3], 4128 sizeof(sin6->sin6_addr.s6_addr32[3])); 4129 } 4130 if (in6_pcbconnect(in6p, am, NULL)) { 4131 (void) m_free(am); 4132 goto resetandabort; 4133 } 4134 } 4135 #endif 4136 else { 4137 (void) m_free(am); 4138 goto resetandabort; 4139 } 4140 (void) m_free(am); 4141 4142 if (inp) 4143 tp = intotcpcb(inp); 4144 #ifdef INET6 4145 else if (in6p) 4146 tp = in6totcpcb(in6p); 4147 #endif 4148 else 4149 tp = NULL; 4150 tp->t_flags = sototcpcb(oso)->t_flags & TF_NODELAY; 4151 if (sc->sc_request_r_scale != 15) { 4152 tp->requested_s_scale = sc->sc_requested_s_scale; 4153 tp->request_r_scale = sc->sc_request_r_scale; 4154 tp->snd_scale = sc->sc_requested_s_scale; 4155 tp->rcv_scale = sc->sc_request_r_scale; 4156 tp->t_flags |= TF_REQ_SCALE|TF_RCVD_SCALE; 4157 } 4158 if (sc->sc_flags & SCF_TIMESTAMP) 4159 tp->t_flags |= TF_REQ_TSTMP|TF_RCVD_TSTMP; 4160 tp->ts_timebase = sc->sc_timebase; 4161 4162 tp->t_template = tcp_template(tp); 4163 if (tp->t_template == 0) { 4164 tp = tcp_drop(tp, ENOBUFS); /* destroys socket */ 4165 so = NULL; 4166 m_freem(m); 4167 goto abort; 4168 } 4169 4170 tp->iss = sc->sc_iss; 4171 tp->irs = sc->sc_irs; 4172 tcp_sendseqinit(tp); 4173 tcp_rcvseqinit(tp); 4174 tp->t_state = TCPS_SYN_RECEIVED; 4175 TCP_TIMER_ARM(tp, TCPT_KEEP, tp->t_keepinit); 4176 TCP_STATINC(TCP_STAT_ACCEPTS); 4177 4178 if ((sc->sc_flags & SCF_SACK_PERMIT) && tcp_do_sack) 4179 tp->t_flags |= TF_WILL_SACK; 4180 4181 if ((sc->sc_flags & SCF_ECN_PERMIT) && tcp_do_ecn) 4182 tp->t_flags |= TF_ECN_PERMIT; 4183 4184 #ifdef TCP_SIGNATURE 4185 if (sc->sc_flags & SCF_SIGNATURE) 4186 tp->t_flags |= TF_SIGNATURE; 4187 #endif 4188 4189 /* Initialize tp->t_ourmss before we deal with the peer's! */ 4190 tp->t_ourmss = sc->sc_ourmaxseg; 4191 tcp_mss_from_peer(tp, sc->sc_peermaxseg); 4192 4193 /* 4194 * Initialize the initial congestion window. If we 4195 * had to retransmit the SYN,ACK, we must initialize cwnd 4196 * to 1 segment (i.e. the Loss Window). 4197 */ 4198 if (sc->sc_rxtshift) 4199 tp->snd_cwnd = tp->t_peermss; 4200 else { 4201 int ss = tcp_init_win; 4202 #ifdef INET 4203 if (inp != NULL && in_localaddr(inp->inp_faddr)) 4204 ss = tcp_init_win_local; 4205 #endif 4206 #ifdef INET6 4207 if (in6p != NULL && in6_localaddr(&in6p->in6p_faddr)) 4208 ss = tcp_init_win_local; 4209 #endif 4210 tp->snd_cwnd = TCP_INITIAL_WINDOW(ss, tp->t_peermss); 4211 } 4212 4213 tcp_rmx_rtt(tp); 4214 tp->snd_wl1 = sc->sc_irs; 4215 tp->rcv_up = sc->sc_irs + 1; 4216 4217 /* 4218 * This is what whould have happened in tcp_output() when 4219 * the SYN,ACK was sent. 4220 */ 4221 tp->snd_up = tp->snd_una; 4222 tp->snd_max = tp->snd_nxt = tp->iss+1; 4223 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 4224 if (sc->sc_win > 0 && SEQ_GT(tp->rcv_nxt + sc->sc_win, tp->rcv_adv)) 4225 tp->rcv_adv = tp->rcv_nxt + sc->sc_win; 4226 tp->last_ack_sent = tp->rcv_nxt; 4227 tp->t_partialacks = -1; 4228 tp->t_dupacks = 0; 4229 4230 TCP_STATINC(TCP_STAT_SC_COMPLETED); 4231 s = splsoftnet(); 4232 syn_cache_put(sc); 4233 splx(s); 4234 return (so); 4235 4236 resetandabort: 4237 (void)tcp_respond(NULL, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 4238 abort: 4239 if (so != NULL) { 4240 (void) soqremque(so, 1); 4241 (void) soabort(so); 4242 mutex_enter(softnet_lock); 4243 } 4244 s = splsoftnet(); 4245 syn_cache_put(sc); 4246 splx(s); 4247 TCP_STATINC(TCP_STAT_SC_ABORTED); 4248 return ((struct socket *)(-1)); 4249 } 4250 4251 /* 4252 * This function is called when we get a RST for a 4253 * non-existent connection, so that we can see if the 4254 * connection is in the syn cache. If it is, zap it. 4255 */ 4256 4257 void 4258 syn_cache_reset(struct sockaddr *src, struct sockaddr *dst, struct tcphdr *th) 4259 { 4260 struct syn_cache *sc; 4261 struct syn_cache_head *scp; 4262 int s = splsoftnet(); 4263 4264 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 4265 splx(s); 4266 return; 4267 } 4268 if (SEQ_LT(th->th_seq, sc->sc_irs) || 4269 SEQ_GT(th->th_seq, sc->sc_irs+1)) { 4270 splx(s); 4271 return; 4272 } 4273 syn_cache_rm(sc); 4274 TCP_STATINC(TCP_STAT_SC_RESET); 4275 syn_cache_put(sc); /* calls pool_put but see spl above */ 4276 splx(s); 4277 } 4278 4279 void 4280 syn_cache_unreach(const struct sockaddr *src, const struct sockaddr *dst, 4281 struct tcphdr *th) 4282 { 4283 struct syn_cache *sc; 4284 struct syn_cache_head *scp; 4285 int s; 4286 4287 s = splsoftnet(); 4288 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 4289 splx(s); 4290 return; 4291 } 4292 /* If the sequence number != sc_iss, then it's a bogus ICMP msg */ 4293 if (ntohl (th->th_seq) != sc->sc_iss) { 4294 splx(s); 4295 return; 4296 } 4297 4298 /* 4299 * If we've retransmitted 3 times and this is our second error, 4300 * we remove the entry. Otherwise, we allow it to continue on. 4301 * This prevents us from incorrectly nuking an entry during a 4302 * spurious network outage. 4303 * 4304 * See tcp_notify(). 4305 */ 4306 if ((sc->sc_flags & SCF_UNREACH) == 0 || sc->sc_rxtshift < 3) { 4307 sc->sc_flags |= SCF_UNREACH; 4308 splx(s); 4309 return; 4310 } 4311 4312 syn_cache_rm(sc); 4313 TCP_STATINC(TCP_STAT_SC_UNREACH); 4314 syn_cache_put(sc); /* calls pool_put but see spl above */ 4315 splx(s); 4316 } 4317 4318 /* 4319 * Given a LISTEN socket and an inbound SYN request, add 4320 * this to the syn cache, and send back a segment: 4321 * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK> 4322 * to the source. 4323 * 4324 * IMPORTANT NOTE: We do _NOT_ ACK data that might accompany the SYN. 4325 * Doing so would require that we hold onto the data and deliver it 4326 * to the application. However, if we are the target of a SYN-flood 4327 * DoS attack, an attacker could send data which would eventually 4328 * consume all available buffer space if it were ACKed. By not ACKing 4329 * the data, we avoid this DoS scenario. 4330 */ 4331 4332 int 4333 syn_cache_add(struct sockaddr *src, struct sockaddr *dst, struct tcphdr *th, 4334 unsigned int hlen, struct socket *so, struct mbuf *m, u_char *optp, 4335 int optlen, struct tcp_opt_info *oi) 4336 { 4337 struct tcpcb tb, *tp; 4338 long win; 4339 struct syn_cache *sc; 4340 struct syn_cache_head *scp; 4341 struct mbuf *ipopts; 4342 struct tcp_opt_info opti; 4343 int s; 4344 4345 tp = sototcpcb(so); 4346 4347 memset(&opti, 0, sizeof(opti)); 4348 4349 /* 4350 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN 4351 * 4352 * Note this check is performed in tcp_input() very early on. 4353 */ 4354 4355 /* 4356 * Initialize some local state. 4357 */ 4358 win = sbspace(&so->so_rcv); 4359 if (win > TCP_MAXWIN) 4360 win = TCP_MAXWIN; 4361 4362 switch (src->sa_family) { 4363 #ifdef INET 4364 case AF_INET: 4365 /* 4366 * Remember the IP options, if any. 4367 */ 4368 ipopts = ip_srcroute(); 4369 break; 4370 #endif 4371 default: 4372 ipopts = NULL; 4373 } 4374 4375 #ifdef TCP_SIGNATURE 4376 if (optp || (tp->t_flags & TF_SIGNATURE)) 4377 #else 4378 if (optp) 4379 #endif 4380 { 4381 tb.t_flags = tcp_do_rfc1323 ? (TF_REQ_SCALE|TF_REQ_TSTMP) : 0; 4382 #ifdef TCP_SIGNATURE 4383 tb.t_flags |= (tp->t_flags & TF_SIGNATURE); 4384 #endif 4385 tb.t_state = TCPS_LISTEN; 4386 if (tcp_dooptions(&tb, optp, optlen, th, m, m->m_pkthdr.len - 4387 sizeof(struct tcphdr) - optlen - hlen, oi) < 0) 4388 return (0); 4389 } else 4390 tb.t_flags = 0; 4391 4392 /* 4393 * See if we already have an entry for this connection. 4394 * If we do, resend the SYN,ACK. We do not count this 4395 * as a retransmission (XXX though maybe we should). 4396 */ 4397 if ((sc = syn_cache_lookup(src, dst, &scp)) != NULL) { 4398 TCP_STATINC(TCP_STAT_SC_DUPESYN); 4399 if (ipopts) { 4400 /* 4401 * If we were remembering a previous source route, 4402 * forget it and use the new one we've been given. 4403 */ 4404 if (sc->sc_ipopts) 4405 (void) m_free(sc->sc_ipopts); 4406 sc->sc_ipopts = ipopts; 4407 } 4408 sc->sc_timestamp = tb.ts_recent; 4409 if (syn_cache_respond(sc, m) == 0) { 4410 uint64_t *tcps = TCP_STAT_GETREF(); 4411 tcps[TCP_STAT_SNDACKS]++; 4412 tcps[TCP_STAT_SNDTOTAL]++; 4413 TCP_STAT_PUTREF(); 4414 } 4415 return (1); 4416 } 4417 4418 s = splsoftnet(); 4419 sc = pool_get(&syn_cache_pool, PR_NOWAIT); 4420 splx(s); 4421 if (sc == NULL) { 4422 if (ipopts) 4423 (void) m_free(ipopts); 4424 return (0); 4425 } 4426 4427 /* 4428 * Fill in the cache, and put the necessary IP and TCP 4429 * options into the reply. 4430 */ 4431 memset(sc, 0, sizeof(struct syn_cache)); 4432 callout_init(&sc->sc_timer, CALLOUT_MPSAFE); 4433 bcopy(src, &sc->sc_src, src->sa_len); 4434 bcopy(dst, &sc->sc_dst, dst->sa_len); 4435 sc->sc_flags = 0; 4436 sc->sc_ipopts = ipopts; 4437 sc->sc_irs = th->th_seq; 4438 switch (src->sa_family) { 4439 #ifdef INET 4440 case AF_INET: 4441 { 4442 struct sockaddr_in *srcin = (void *) src; 4443 struct sockaddr_in *dstin = (void *) dst; 4444 4445 sc->sc_iss = tcp_new_iss1(&dstin->sin_addr, 4446 &srcin->sin_addr, dstin->sin_port, 4447 srcin->sin_port, sizeof(dstin->sin_addr), 0); 4448 break; 4449 } 4450 #endif /* INET */ 4451 #ifdef INET6 4452 case AF_INET6: 4453 { 4454 struct sockaddr_in6 *srcin6 = (void *) src; 4455 struct sockaddr_in6 *dstin6 = (void *) dst; 4456 4457 sc->sc_iss = tcp_new_iss1(&dstin6->sin6_addr, 4458 &srcin6->sin6_addr, dstin6->sin6_port, 4459 srcin6->sin6_port, sizeof(dstin6->sin6_addr), 0); 4460 break; 4461 } 4462 #endif /* INET6 */ 4463 } 4464 sc->sc_peermaxseg = oi->maxseg; 4465 sc->sc_ourmaxseg = tcp_mss_to_advertise(m->m_flags & M_PKTHDR ? 4466 m->m_pkthdr.rcvif : NULL, 4467 sc->sc_src.sa.sa_family); 4468 sc->sc_win = win; 4469 sc->sc_timebase = tcp_now - 1; /* see tcp_newtcpcb() */ 4470 sc->sc_timestamp = tb.ts_recent; 4471 if ((tb.t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP)) == 4472 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) 4473 sc->sc_flags |= SCF_TIMESTAMP; 4474 if ((tb.t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 4475 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 4476 sc->sc_requested_s_scale = tb.requested_s_scale; 4477 sc->sc_request_r_scale = 0; 4478 /* 4479 * Pick the smallest possible scaling factor that 4480 * will still allow us to scale up to sb_max. 4481 * 4482 * We do this because there are broken firewalls that 4483 * will corrupt the window scale option, leading to 4484 * the other endpoint believing that our advertised 4485 * window is unscaled. At scale factors larger than 4486 * 5 the unscaled window will drop below 1500 bytes, 4487 * leading to serious problems when traversing these 4488 * broken firewalls. 4489 * 4490 * With the default sbmax of 256K, a scale factor 4491 * of 3 will be chosen by this algorithm. Those who 4492 * choose a larger sbmax should watch out 4493 * for the compatiblity problems mentioned above. 4494 * 4495 * RFC1323: The Window field in a SYN (i.e., a <SYN> 4496 * or <SYN,ACK>) segment itself is never scaled. 4497 */ 4498 while (sc->sc_request_r_scale < TCP_MAX_WINSHIFT && 4499 (TCP_MAXWIN << sc->sc_request_r_scale) < sb_max) 4500 sc->sc_request_r_scale++; 4501 } else { 4502 sc->sc_requested_s_scale = 15; 4503 sc->sc_request_r_scale = 15; 4504 } 4505 if ((tb.t_flags & TF_SACK_PERMIT) && tcp_do_sack) 4506 sc->sc_flags |= SCF_SACK_PERMIT; 4507 4508 /* 4509 * ECN setup packet recieved. 4510 */ 4511 if ((th->th_flags & (TH_ECE|TH_CWR)) && tcp_do_ecn) 4512 sc->sc_flags |= SCF_ECN_PERMIT; 4513 4514 #ifdef TCP_SIGNATURE 4515 if (tb.t_flags & TF_SIGNATURE) 4516 sc->sc_flags |= SCF_SIGNATURE; 4517 #endif 4518 sc->sc_tp = tp; 4519 if (syn_cache_respond(sc, m) == 0) { 4520 uint64_t *tcps = TCP_STAT_GETREF(); 4521 tcps[TCP_STAT_SNDACKS]++; 4522 tcps[TCP_STAT_SNDTOTAL]++; 4523 TCP_STAT_PUTREF(); 4524 syn_cache_insert(sc, tp); 4525 } else { 4526 s = splsoftnet(); 4527 /* 4528 * syn_cache_put() will try to schedule the timer, so 4529 * we need to initialize it 4530 */ 4531 SYN_CACHE_TIMER_ARM(sc); 4532 syn_cache_put(sc); 4533 splx(s); 4534 TCP_STATINC(TCP_STAT_SC_DROPPED); 4535 } 4536 return (1); 4537 } 4538 4539 int 4540 syn_cache_respond(struct syn_cache *sc, struct mbuf *m) 4541 { 4542 #ifdef INET6 4543 struct rtentry *rt; 4544 #endif 4545 struct route *ro; 4546 u_int8_t *optp; 4547 int optlen, error; 4548 u_int16_t tlen; 4549 struct ip *ip = NULL; 4550 #ifdef INET6 4551 struct ip6_hdr *ip6 = NULL; 4552 #endif 4553 struct tcpcb *tp = NULL; 4554 struct tcphdr *th; 4555 u_int hlen; 4556 struct socket *so; 4557 4558 ro = &sc->sc_route; 4559 switch (sc->sc_src.sa.sa_family) { 4560 case AF_INET: 4561 hlen = sizeof(struct ip); 4562 break; 4563 #ifdef INET6 4564 case AF_INET6: 4565 hlen = sizeof(struct ip6_hdr); 4566 break; 4567 #endif 4568 default: 4569 if (m) 4570 m_freem(m); 4571 return (EAFNOSUPPORT); 4572 } 4573 4574 /* Compute the size of the TCP options. */ 4575 optlen = 4 + (sc->sc_request_r_scale != 15 ? 4 : 0) + 4576 ((sc->sc_flags & SCF_SACK_PERMIT) ? (TCPOLEN_SACK_PERMITTED + 2) : 0) + 4577 #ifdef TCP_SIGNATURE 4578 ((sc->sc_flags & SCF_SIGNATURE) ? (TCPOLEN_SIGNATURE + 2) : 0) + 4579 #endif 4580 ((sc->sc_flags & SCF_TIMESTAMP) ? TCPOLEN_TSTAMP_APPA : 0); 4581 4582 tlen = hlen + sizeof(struct tcphdr) + optlen; 4583 4584 /* 4585 * Create the IP+TCP header from scratch. 4586 */ 4587 if (m) 4588 m_freem(m); 4589 #ifdef DIAGNOSTIC 4590 if (max_linkhdr + tlen > MCLBYTES) 4591 return (ENOBUFS); 4592 #endif 4593 MGETHDR(m, M_DONTWAIT, MT_DATA); 4594 if (m && (max_linkhdr + tlen) > MHLEN) { 4595 MCLGET(m, M_DONTWAIT); 4596 if ((m->m_flags & M_EXT) == 0) { 4597 m_freem(m); 4598 m = NULL; 4599 } 4600 } 4601 if (m == NULL) 4602 return (ENOBUFS); 4603 MCLAIM(m, &tcp_tx_mowner); 4604 4605 /* Fixup the mbuf. */ 4606 m->m_data += max_linkhdr; 4607 m->m_len = m->m_pkthdr.len = tlen; 4608 if (sc->sc_tp) { 4609 tp = sc->sc_tp; 4610 if (tp->t_inpcb) 4611 so = tp->t_inpcb->inp_socket; 4612 #ifdef INET6 4613 else if (tp->t_in6pcb) 4614 so = tp->t_in6pcb->in6p_socket; 4615 #endif 4616 else 4617 so = NULL; 4618 } else 4619 so = NULL; 4620 m->m_pkthdr.rcvif = NULL; 4621 memset(mtod(m, u_char *), 0, tlen); 4622 4623 switch (sc->sc_src.sa.sa_family) { 4624 case AF_INET: 4625 ip = mtod(m, struct ip *); 4626 ip->ip_v = 4; 4627 ip->ip_dst = sc->sc_src.sin.sin_addr; 4628 ip->ip_src = sc->sc_dst.sin.sin_addr; 4629 ip->ip_p = IPPROTO_TCP; 4630 th = (struct tcphdr *)(ip + 1); 4631 th->th_dport = sc->sc_src.sin.sin_port; 4632 th->th_sport = sc->sc_dst.sin.sin_port; 4633 break; 4634 #ifdef INET6 4635 case AF_INET6: 4636 ip6 = mtod(m, struct ip6_hdr *); 4637 ip6->ip6_vfc = IPV6_VERSION; 4638 ip6->ip6_dst = sc->sc_src.sin6.sin6_addr; 4639 ip6->ip6_src = sc->sc_dst.sin6.sin6_addr; 4640 ip6->ip6_nxt = IPPROTO_TCP; 4641 /* ip6_plen will be updated in ip6_output() */ 4642 th = (struct tcphdr *)(ip6 + 1); 4643 th->th_dport = sc->sc_src.sin6.sin6_port; 4644 th->th_sport = sc->sc_dst.sin6.sin6_port; 4645 break; 4646 #endif 4647 default: 4648 th = NULL; 4649 } 4650 4651 th->th_seq = htonl(sc->sc_iss); 4652 th->th_ack = htonl(sc->sc_irs + 1); 4653 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 4654 th->th_flags = TH_SYN|TH_ACK; 4655 th->th_win = htons(sc->sc_win); 4656 /* th_sum already 0 */ 4657 /* th_urp already 0 */ 4658 4659 /* Tack on the TCP options. */ 4660 optp = (u_int8_t *)(th + 1); 4661 *optp++ = TCPOPT_MAXSEG; 4662 *optp++ = 4; 4663 *optp++ = (sc->sc_ourmaxseg >> 8) & 0xff; 4664 *optp++ = sc->sc_ourmaxseg & 0xff; 4665 4666 if (sc->sc_request_r_scale != 15) { 4667 *((u_int32_t *)optp) = htonl(TCPOPT_NOP << 24 | 4668 TCPOPT_WINDOW << 16 | TCPOLEN_WINDOW << 8 | 4669 sc->sc_request_r_scale); 4670 optp += 4; 4671 } 4672 4673 if (sc->sc_flags & SCF_TIMESTAMP) { 4674 u_int32_t *lp = (u_int32_t *)(optp); 4675 /* Form timestamp option as shown in appendix A of RFC 1323. */ 4676 *lp++ = htonl(TCPOPT_TSTAMP_HDR); 4677 *lp++ = htonl(SYN_CACHE_TIMESTAMP(sc)); 4678 *lp = htonl(sc->sc_timestamp); 4679 optp += TCPOLEN_TSTAMP_APPA; 4680 } 4681 4682 if (sc->sc_flags & SCF_SACK_PERMIT) { 4683 u_int8_t *p = optp; 4684 4685 /* Let the peer know that we will SACK. */ 4686 p[0] = TCPOPT_SACK_PERMITTED; 4687 p[1] = 2; 4688 p[2] = TCPOPT_NOP; 4689 p[3] = TCPOPT_NOP; 4690 optp += 4; 4691 } 4692 4693 /* 4694 * Send ECN SYN-ACK setup packet. 4695 * Routes can be asymetric, so, even if we receive a packet 4696 * with ECE and CWR set, we must not assume no one will block 4697 * the ECE packet we are about to send. 4698 */ 4699 if ((sc->sc_flags & SCF_ECN_PERMIT) && tp && 4700 SEQ_GEQ(tp->snd_nxt, tp->snd_max)) { 4701 th->th_flags |= TH_ECE; 4702 TCP_STATINC(TCP_STAT_ECN_SHS); 4703 4704 /* 4705 * draft-ietf-tcpm-ecnsyn-00.txt 4706 * 4707 * "[...] a TCP node MAY respond to an ECN-setup 4708 * SYN packet by setting ECT in the responding 4709 * ECN-setup SYN/ACK packet, indicating to routers 4710 * that the SYN/ACK packet is ECN-Capable. 4711 * This allows a congested router along the path 4712 * to mark the packet instead of dropping the 4713 * packet as an indication of congestion." 4714 * 4715 * "[...] There can be a great benefit in setting 4716 * an ECN-capable codepoint in SYN/ACK packets [...] 4717 * Congestion is most likely to occur in 4718 * the server-to-client direction. As a result, 4719 * setting an ECN-capable codepoint in SYN/ACK 4720 * packets can reduce the occurence of three-second 4721 * retransmit timeouts resulting from the drop 4722 * of SYN/ACK packets." 4723 * 4724 * Page 4 and 6, January 2006. 4725 */ 4726 4727 switch (sc->sc_src.sa.sa_family) { 4728 #ifdef INET 4729 case AF_INET: 4730 ip->ip_tos |= IPTOS_ECN_ECT0; 4731 break; 4732 #endif 4733 #ifdef INET6 4734 case AF_INET6: 4735 ip6->ip6_flow |= htonl(IPTOS_ECN_ECT0 << 20); 4736 break; 4737 #endif 4738 } 4739 TCP_STATINC(TCP_STAT_ECN_ECT); 4740 } 4741 4742 #ifdef TCP_SIGNATURE 4743 if (sc->sc_flags & SCF_SIGNATURE) { 4744 struct secasvar *sav; 4745 u_int8_t *sigp; 4746 4747 sav = tcp_signature_getsav(m, th); 4748 4749 if (sav == NULL) { 4750 if (m) 4751 m_freem(m); 4752 return (EPERM); 4753 } 4754 4755 *optp++ = TCPOPT_SIGNATURE; 4756 *optp++ = TCPOLEN_SIGNATURE; 4757 sigp = optp; 4758 memset(optp, 0, TCP_SIGLEN); 4759 optp += TCP_SIGLEN; 4760 *optp++ = TCPOPT_NOP; 4761 *optp++ = TCPOPT_EOL; 4762 4763 (void)tcp_signature(m, th, hlen, sav, sigp); 4764 4765 key_sa_recordxfer(sav, m); 4766 #ifdef FAST_IPSEC 4767 KEY_FREESAV(&sav); 4768 #else 4769 key_freesav(sav); 4770 #endif 4771 } 4772 #endif 4773 4774 /* Compute the packet's checksum. */ 4775 switch (sc->sc_src.sa.sa_family) { 4776 case AF_INET: 4777 ip->ip_len = htons(tlen - hlen); 4778 th->th_sum = 0; 4779 th->th_sum = in4_cksum(m, IPPROTO_TCP, hlen, tlen - hlen); 4780 break; 4781 #ifdef INET6 4782 case AF_INET6: 4783 ip6->ip6_plen = htons(tlen - hlen); 4784 th->th_sum = 0; 4785 th->th_sum = in6_cksum(m, IPPROTO_TCP, hlen, tlen - hlen); 4786 break; 4787 #endif 4788 } 4789 4790 /* 4791 * Fill in some straggling IP bits. Note the stack expects 4792 * ip_len to be in host order, for convenience. 4793 */ 4794 switch (sc->sc_src.sa.sa_family) { 4795 #ifdef INET 4796 case AF_INET: 4797 ip->ip_len = htons(tlen); 4798 ip->ip_ttl = ip_defttl; 4799 /* XXX tos? */ 4800 break; 4801 #endif 4802 #ifdef INET6 4803 case AF_INET6: 4804 ip6->ip6_vfc &= ~IPV6_VERSION_MASK; 4805 ip6->ip6_vfc |= IPV6_VERSION; 4806 ip6->ip6_plen = htons(tlen - hlen); 4807 /* ip6_hlim will be initialized afterwards */ 4808 /* XXX flowlabel? */ 4809 break; 4810 #endif 4811 } 4812 4813 /* XXX use IPsec policy on listening socket, on SYN ACK */ 4814 tp = sc->sc_tp; 4815 4816 switch (sc->sc_src.sa.sa_family) { 4817 #ifdef INET 4818 case AF_INET: 4819 error = ip_output(m, sc->sc_ipopts, ro, 4820 (ip_mtudisc ? IP_MTUDISC : 0), 4821 NULL, so); 4822 break; 4823 #endif 4824 #ifdef INET6 4825 case AF_INET6: 4826 ip6->ip6_hlim = in6_selecthlim(NULL, 4827 (rt = rtcache_validate(ro)) != NULL ? rt->rt_ifp 4828 : NULL); 4829 4830 error = ip6_output(m, NULL /*XXX*/, ro, 0, NULL, so, NULL); 4831 break; 4832 #endif 4833 default: 4834 error = EAFNOSUPPORT; 4835 break; 4836 } 4837 return (error); 4838 } 4839
Indexes created Tue Sep 23 07:09:52 GMT 2025