1 /* $NetBSD: tcp_input.c,v 1.406 2018/04/28 13:26:57 maxv 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 1.406 2018/04/28 13:26:57 maxv Exp $"); 152 153 #ifdef _KERNEL_OPT 154 #include "opt_inet.h" 155 #include "opt_ipsec.h" 156 #include "opt_inet_csum.h" 157 #include "opt_tcp_debug.h" 158 #endif 159 160 #include <sys/param.h> 161 #include <sys/systm.h> 162 #include <sys/malloc.h> 163 #include <sys/mbuf.h> 164 #include <sys/protosw.h> 165 #include <sys/socket.h> 166 #include <sys/socketvar.h> 167 #include <sys/errno.h> 168 #include <sys/syslog.h> 169 #include <sys/pool.h> 170 #include <sys/domain.h> 171 #include <sys/kernel.h> 172 #ifdef TCP_SIGNATURE 173 #include <sys/md5.h> 174 #endif 175 #include <sys/lwp.h> /* for lwp0 */ 176 #include <sys/cprng.h> 177 178 #include <net/if.h> 179 #include <net/if_types.h> 180 181 #include <netinet/in.h> 182 #include <netinet/in_systm.h> 183 #include <netinet/ip.h> 184 #include <netinet/in_pcb.h> 185 #include <netinet/in_var.h> 186 #include <netinet/ip_var.h> 187 #include <netinet/in_offload.h> 188 189 #ifdef INET6 190 #include <netinet/ip6.h> 191 #include <netinet6/ip6_var.h> 192 #include <netinet6/in6_pcb.h> 193 #include <netinet6/ip6_var.h> 194 #include <netinet6/in6_var.h> 195 #include <netinet/icmp6.h> 196 #include <netinet6/nd6.h> 197 #ifdef TCP_SIGNATURE 198 #include <netinet6/scope6_var.h> 199 #endif 200 #endif 201 202 #ifndef INET6 203 /* always need ip6.h for IP6_EXTHDR_GET */ 204 #include <netinet/ip6.h> 205 #endif 206 207 #include <netinet/tcp.h> 208 #include <netinet/tcp_fsm.h> 209 #include <netinet/tcp_seq.h> 210 #include <netinet/tcp_timer.h> 211 #include <netinet/tcp_var.h> 212 #include <netinet/tcp_private.h> 213 #include <netinet/tcpip.h> 214 #include <netinet/tcp_congctl.h> 215 #include <netinet/tcp_debug.h> 216 217 #ifdef INET6 218 #include "faith.h" 219 #if defined(NFAITH) && NFAITH > 0 220 #include <net/if_faith.h> 221 #endif 222 #endif 223 224 #ifdef IPSEC 225 #include <netipsec/ipsec.h> 226 #include <netipsec/key.h> 227 #ifdef INET6 228 #include <netipsec/ipsec6.h> 229 #endif 230 #endif /* IPSEC*/ 231 232 #include <netinet/tcp_vtw.h> 233 234 int tcprexmtthresh = 3; 235 int tcp_log_refused; 236 237 int tcp_do_autorcvbuf = 1; 238 int tcp_autorcvbuf_inc = 16 * 1024; 239 int tcp_autorcvbuf_max = 256 * 1024; 240 int tcp_msl = (TCPTV_MSL / PR_SLOWHZ); 241 242 static int tcp_rst_ppslim_count = 0; 243 static struct timeval tcp_rst_ppslim_last; 244 static int tcp_ackdrop_ppslim_count = 0; 245 static struct timeval tcp_ackdrop_ppslim_last; 246 247 static void syn_cache_timer(void *); 248 249 #define TCP_PAWS_IDLE (24U * 24 * 60 * 60 * PR_SLOWHZ) 250 251 /* for modulo comparisons of timestamps */ 252 #define TSTMP_LT(a,b) ((int)((a)-(b)) < 0) 253 #define TSTMP_GEQ(a,b) ((int)((a)-(b)) >= 0) 254 255 /* 256 * Neighbor Discovery, Neighbor Unreachability Detection Upper layer hint. 257 */ 258 #ifdef INET6 259 static inline void 260 nd6_hint(struct tcpcb *tp) 261 { 262 struct rtentry *rt = NULL; 263 264 if (tp != NULL && tp->t_in6pcb != NULL && tp->t_family == AF_INET6 && 265 (rt = rtcache_validate(&tp->t_in6pcb->in6p_route)) != NULL) 266 nd6_nud_hint(rt); 267 rtcache_unref(rt, &tp->t_in6pcb->in6p_route); 268 } 269 #else 270 static inline void 271 nd6_hint(struct tcpcb *tp) 272 { 273 } 274 #endif 275 276 /* 277 * Compute ACK transmission behavior. Delay the ACK unless 278 * we have already delayed an ACK (must send an ACK every two segments). 279 * We also ACK immediately if we received a PUSH and the ACK-on-PUSH 280 * option is enabled. 281 */ 282 static void 283 tcp_setup_ack(struct tcpcb *tp, const struct tcphdr *th) 284 { 285 286 if (tp->t_flags & TF_DELACK || 287 (tcp_ack_on_push && th->th_flags & TH_PUSH)) 288 tp->t_flags |= TF_ACKNOW; 289 else 290 TCP_SET_DELACK(tp); 291 } 292 293 static void 294 icmp_check(struct tcpcb *tp, const struct tcphdr *th, int acked) 295 { 296 297 /* 298 * If we had a pending ICMP message that refers to data that have 299 * just been acknowledged, disregard the recorded ICMP message. 300 */ 301 if ((tp->t_flags & TF_PMTUD_PEND) && 302 SEQ_GT(th->th_ack, tp->t_pmtud_th_seq)) 303 tp->t_flags &= ~TF_PMTUD_PEND; 304 305 /* 306 * Keep track of the largest chunk of data 307 * acknowledged since last PMTU update 308 */ 309 if (tp->t_pmtud_mss_acked < acked) 310 tp->t_pmtud_mss_acked = acked; 311 } 312 313 /* 314 * Convert TCP protocol fields to host order for easier processing. 315 */ 316 static void 317 tcp_fields_to_host(struct tcphdr *th) 318 { 319 320 NTOHL(th->th_seq); 321 NTOHL(th->th_ack); 322 NTOHS(th->th_win); 323 NTOHS(th->th_urp); 324 } 325 326 /* 327 * ... and reverse the above. 328 */ 329 static void 330 tcp_fields_to_net(struct tcphdr *th) 331 { 332 333 HTONL(th->th_seq); 334 HTONL(th->th_ack); 335 HTONS(th->th_win); 336 HTONS(th->th_urp); 337 } 338 339 static void 340 tcp_urp_drop(struct tcphdr *th, int todrop, int *tiflags) 341 { 342 if (th->th_urp > todrop) { 343 th->th_urp -= todrop; 344 } else { 345 *tiflags &= ~TH_URG; 346 th->th_urp = 0; 347 } 348 } 349 350 #ifdef TCP_CSUM_COUNTERS 351 #include <sys/device.h> 352 353 extern struct evcnt tcp_hwcsum_ok; 354 extern struct evcnt tcp_hwcsum_bad; 355 extern struct evcnt tcp_hwcsum_data; 356 extern struct evcnt tcp_swcsum; 357 #if defined(INET6) 358 extern struct evcnt tcp6_hwcsum_ok; 359 extern struct evcnt tcp6_hwcsum_bad; 360 extern struct evcnt tcp6_hwcsum_data; 361 extern struct evcnt tcp6_swcsum; 362 #endif /* defined(INET6) */ 363 364 #define TCP_CSUM_COUNTER_INCR(ev) (ev)->ev_count++ 365 366 #else 367 368 #define TCP_CSUM_COUNTER_INCR(ev) /* nothing */ 369 370 #endif /* TCP_CSUM_COUNTERS */ 371 372 #ifdef TCP_REASS_COUNTERS 373 #include <sys/device.h> 374 375 extern struct evcnt tcp_reass_; 376 extern struct evcnt tcp_reass_empty; 377 extern struct evcnt tcp_reass_iteration[8]; 378 extern struct evcnt tcp_reass_prependfirst; 379 extern struct evcnt tcp_reass_prepend; 380 extern struct evcnt tcp_reass_insert; 381 extern struct evcnt tcp_reass_inserttail; 382 extern struct evcnt tcp_reass_append; 383 extern struct evcnt tcp_reass_appendtail; 384 extern struct evcnt tcp_reass_overlaptail; 385 extern struct evcnt tcp_reass_overlapfront; 386 extern struct evcnt tcp_reass_segdup; 387 extern struct evcnt tcp_reass_fragdup; 388 389 #define TCP_REASS_COUNTER_INCR(ev) (ev)->ev_count++ 390 391 #else 392 393 #define TCP_REASS_COUNTER_INCR(ev) /* nothing */ 394 395 #endif /* TCP_REASS_COUNTERS */ 396 397 static int tcp_reass(struct tcpcb *, const struct tcphdr *, struct mbuf *, 398 int); 399 static int tcp_dooptions(struct tcpcb *, const u_char *, int, 400 struct tcphdr *, struct mbuf *, int, struct tcp_opt_info *); 401 402 static void tcp4_log_refused(const struct ip *, const struct tcphdr *); 403 #ifdef INET6 404 static void tcp6_log_refused(const struct ip6_hdr *, const struct tcphdr *); 405 #endif 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 /* 445 * Insert segment ti into reassembly queue of tcp with 446 * control block tp. Return TH_FIN if reassembly now includes 447 * a segment with FIN. 448 */ 449 static int 450 tcp_reass(struct tcpcb *tp, const struct tcphdr *th, struct mbuf *m, int tlen) 451 { 452 struct ipqent *p, *q, *nq, *tiqe = NULL; 453 struct socket *so = NULL; 454 int pkt_flags; 455 tcp_seq pkt_seq; 456 unsigned pkt_len; 457 u_long rcvpartdupbyte = 0; 458 u_long rcvoobyte; 459 #ifdef TCP_REASS_COUNTERS 460 u_int count = 0; 461 #endif 462 uint64_t *tcps; 463 464 if (tp->t_inpcb) 465 so = tp->t_inpcb->inp_socket; 466 #ifdef INET6 467 else if (tp->t_in6pcb) 468 so = tp->t_in6pcb->in6p_socket; 469 #endif 470 471 TCP_REASS_LOCK_CHECK(tp); 472 473 /* 474 * Call with th==NULL after become established to 475 * force pre-ESTABLISHED data up to user socket. 476 */ 477 if (th == NULL) 478 goto present; 479 480 m_claimm(m, &tcp_reass_mowner); 481 482 rcvoobyte = tlen; 483 /* 484 * Copy these to local variables because the TCP header gets munged 485 * while we are collapsing mbufs. 486 */ 487 pkt_seq = th->th_seq; 488 pkt_len = tlen; 489 pkt_flags = th->th_flags; 490 491 TCP_REASS_COUNTER_INCR(&tcp_reass_); 492 493 if ((p = TAILQ_LAST(&tp->segq, ipqehead)) != NULL) { 494 /* 495 * When we miss a packet, the vast majority of time we get 496 * packets that follow it in order. So optimize for that. 497 */ 498 if (pkt_seq == p->ipqe_seq + p->ipqe_len) { 499 p->ipqe_len += pkt_len; 500 p->ipqe_flags |= pkt_flags; 501 m_cat(p->ipqe_m, m); 502 m = NULL; 503 tiqe = p; 504 TAILQ_REMOVE(&tp->timeq, p, ipqe_timeq); 505 TCP_REASS_COUNTER_INCR(&tcp_reass_appendtail); 506 goto skip_replacement; 507 } 508 /* 509 * While we're here, if the pkt is completely beyond 510 * anything we have, just insert it at the tail. 511 */ 512 if (SEQ_GT(pkt_seq, p->ipqe_seq + p->ipqe_len)) { 513 TCP_REASS_COUNTER_INCR(&tcp_reass_inserttail); 514 goto insert_it; 515 } 516 } 517 518 q = TAILQ_FIRST(&tp->segq); 519 520 if (q != NULL) { 521 /* 522 * If this segment immediately precedes the first out-of-order 523 * block, simply slap the segment in front of it and (mostly) 524 * skip the complicated logic. 525 */ 526 if (pkt_seq + pkt_len == q->ipqe_seq) { 527 q->ipqe_seq = pkt_seq; 528 q->ipqe_len += pkt_len; 529 q->ipqe_flags |= pkt_flags; 530 m_cat(m, q->ipqe_m); 531 q->ipqe_m = m; 532 tiqe = q; 533 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 534 TCP_REASS_COUNTER_INCR(&tcp_reass_prependfirst); 535 goto skip_replacement; 536 } 537 } else { 538 TCP_REASS_COUNTER_INCR(&tcp_reass_empty); 539 } 540 541 /* 542 * Find a segment which begins after this one does. 543 */ 544 for (p = NULL; q != NULL; q = nq) { 545 nq = TAILQ_NEXT(q, ipqe_q); 546 #ifdef TCP_REASS_COUNTERS 547 count++; 548 #endif 549 550 /* 551 * If the received segment is just right after this 552 * fragment, merge the two together and then check 553 * for further overlaps. 554 */ 555 if (q->ipqe_seq + q->ipqe_len == pkt_seq) { 556 pkt_len += q->ipqe_len; 557 pkt_flags |= q->ipqe_flags; 558 pkt_seq = q->ipqe_seq; 559 m_cat(q->ipqe_m, m); 560 m = q->ipqe_m; 561 TCP_REASS_COUNTER_INCR(&tcp_reass_append); 562 goto free_ipqe; 563 } 564 565 /* 566 * If the received segment is completely past this 567 * fragment, we need to go to the next fragment. 568 */ 569 if (SEQ_LT(q->ipqe_seq + q->ipqe_len, pkt_seq)) { 570 p = q; 571 continue; 572 } 573 574 /* 575 * If the fragment is past the received segment, 576 * it (or any following) can't be concatenated. 577 */ 578 if (SEQ_GT(q->ipqe_seq, pkt_seq + pkt_len)) { 579 TCP_REASS_COUNTER_INCR(&tcp_reass_insert); 580 break; 581 } 582 583 /* 584 * We've received all the data in this segment before. 585 * Mark it as a duplicate and return. 586 */ 587 if (SEQ_LEQ(q->ipqe_seq, pkt_seq) && 588 SEQ_GEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) { 589 tcps = TCP_STAT_GETREF(); 590 tcps[TCP_STAT_RCVDUPPACK]++; 591 tcps[TCP_STAT_RCVDUPBYTE] += pkt_len; 592 TCP_STAT_PUTREF(); 593 tcp_new_dsack(tp, pkt_seq, pkt_len); 594 m_freem(m); 595 if (tiqe != NULL) { 596 tcpipqent_free(tiqe); 597 } 598 TCP_REASS_COUNTER_INCR(&tcp_reass_segdup); 599 goto out; 600 } 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 /* 616 * Received segment extends past the end of the fragment. 617 * Drop the overlapping bytes, merge the fragment and 618 * segment, and treat as 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 m_adj(m, overlap); 624 rcvpartdupbyte += overlap; 625 m_cat(q->ipqe_m, m); 626 m = q->ipqe_m; 627 pkt_seq = q->ipqe_seq; 628 pkt_len += q->ipqe_len - overlap; 629 rcvoobyte -= overlap; 630 TCP_REASS_COUNTER_INCR(&tcp_reass_overlaptail); 631 goto free_ipqe; 632 } 633 634 /* 635 * Received segment extends past the front of the fragment. 636 * Drop the overlapping bytes on the received packet. The 637 * packet will then be concatenated with this fragment a 638 * bit later. 639 */ 640 if (SEQ_GT(q->ipqe_seq, pkt_seq) && 641 SEQ_LT(q->ipqe_seq, pkt_seq + pkt_len)) { 642 int overlap = pkt_seq + pkt_len - q->ipqe_seq; 643 m_adj(m, -overlap); 644 pkt_len -= overlap; 645 rcvpartdupbyte += overlap; 646 TCP_REASS_COUNTER_INCR(&tcp_reass_overlapfront); 647 rcvoobyte -= overlap; 648 } 649 650 /* 651 * If the received segment immediately precedes this 652 * fragment then tack the fragment onto this segment 653 * and reinsert the data. 654 */ 655 if (q->ipqe_seq == pkt_seq + pkt_len) { 656 pkt_len += q->ipqe_len; 657 pkt_flags |= q->ipqe_flags; 658 m_cat(m, q->ipqe_m); 659 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 660 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 661 tp->t_segqlen--; 662 KASSERT(tp->t_segqlen >= 0); 663 KASSERT(tp->t_segqlen != 0 || 664 (TAILQ_EMPTY(&tp->segq) && 665 TAILQ_EMPTY(&tp->timeq))); 666 if (tiqe == NULL) { 667 tiqe = q; 668 } else { 669 tcpipqent_free(q); 670 } 671 TCP_REASS_COUNTER_INCR(&tcp_reass_prepend); 672 break; 673 } 674 675 /* 676 * If the fragment is before the segment, remember it. 677 * When this loop is terminated, p will contain the 678 * pointer to the fragment that is right before the 679 * received segment. 680 */ 681 if (SEQ_LEQ(q->ipqe_seq, pkt_seq)) 682 p = q; 683 684 continue; 685 686 /* 687 * This is a common operation. It also will allow 688 * to save doing a malloc/free in most instances. 689 */ 690 free_ipqe: 691 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 692 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 693 tp->t_segqlen--; 694 KASSERT(tp->t_segqlen >= 0); 695 KASSERT(tp->t_segqlen != 0 || 696 (TAILQ_EMPTY(&tp->segq) && TAILQ_EMPTY(&tp->timeq))); 697 if (tiqe == NULL) { 698 tiqe = q; 699 } else { 700 tcpipqent_free(q); 701 } 702 } 703 704 #ifdef TCP_REASS_COUNTERS 705 if (count > 7) 706 TCP_REASS_COUNTER_INCR(&tcp_reass_iteration[0]); 707 else if (count > 0) 708 TCP_REASS_COUNTER_INCR(&tcp_reass_iteration[count]); 709 #endif 710 711 insert_it: 712 /* 713 * Allocate a new queue entry (block) since the received segment 714 * did not collapse onto any other out-of-order block. If it had 715 * collapsed, tiqe would not be NULL and we would be reusing it. 716 * 717 * If the allocation fails, drop the packet. 718 */ 719 if (tiqe == NULL) { 720 tiqe = tcpipqent_alloc(); 721 if (tiqe == NULL) { 722 TCP_STATINC(TCP_STAT_RCVMEMDROP); 723 m_freem(m); 724 goto out; 725 } 726 } 727 728 /* 729 * Update the counters. 730 */ 731 tp->t_rcvoopack++; 732 tcps = TCP_STAT_GETREF(); 733 tcps[TCP_STAT_RCVOOPACK]++; 734 tcps[TCP_STAT_RCVOOBYTE] += rcvoobyte; 735 if (rcvpartdupbyte) { 736 tcps[TCP_STAT_RCVPARTDUPPACK]++; 737 tcps[TCP_STAT_RCVPARTDUPBYTE] += rcvpartdupbyte; 738 } 739 TCP_STAT_PUTREF(); 740 741 /* 742 * Insert the new fragment queue entry into both queues. 743 */ 744 tiqe->ipqe_m = m; 745 tiqe->ipqe_seq = pkt_seq; 746 tiqe->ipqe_len = pkt_len; 747 tiqe->ipqe_flags = pkt_flags; 748 if (p == NULL) { 749 TAILQ_INSERT_HEAD(&tp->segq, tiqe, ipqe_q); 750 } else { 751 TAILQ_INSERT_AFTER(&tp->segq, p, tiqe, ipqe_q); 752 } 753 tp->t_segqlen++; 754 755 skip_replacement: 756 TAILQ_INSERT_HEAD(&tp->timeq, tiqe, ipqe_timeq); 757 758 present: 759 /* 760 * Present data to user, advancing rcv_nxt through 761 * completed sequence space. 762 */ 763 if (TCPS_HAVEESTABLISHED(tp->t_state) == 0) 764 goto out; 765 q = TAILQ_FIRST(&tp->segq); 766 if (q == NULL || q->ipqe_seq != tp->rcv_nxt) 767 goto out; 768 if (tp->t_state == TCPS_SYN_RECEIVED && q->ipqe_len) 769 goto out; 770 771 tp->rcv_nxt += q->ipqe_len; 772 pkt_flags = q->ipqe_flags & TH_FIN; 773 nd6_hint(tp); 774 775 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 776 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 777 tp->t_segqlen--; 778 KASSERT(tp->t_segqlen >= 0); 779 KASSERT(tp->t_segqlen != 0 || 780 (TAILQ_EMPTY(&tp->segq) && TAILQ_EMPTY(&tp->timeq))); 781 if (so->so_state & SS_CANTRCVMORE) 782 m_freem(q->ipqe_m); 783 else 784 sbappendstream(&so->so_rcv, q->ipqe_m); 785 tcpipqent_free(q); 786 TCP_REASS_UNLOCK(tp); 787 sorwakeup(so); 788 return pkt_flags; 789 790 out: 791 TCP_REASS_UNLOCK(tp); 792 return 0; 793 } 794 795 #ifdef INET6 796 int 797 tcp6_input(struct mbuf **mp, int *offp, int proto) 798 { 799 struct mbuf *m = *mp; 800 801 /* 802 * draft-itojun-ipv6-tcp-to-anycast 803 * better place to put this in? 804 */ 805 if (m->m_flags & M_ANYCAST6) { 806 struct ip6_hdr *ip6; 807 if (m->m_len < sizeof(struct ip6_hdr)) { 808 if ((m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) { 809 TCP_STATINC(TCP_STAT_RCVSHORT); 810 return IPPROTO_DONE; 811 } 812 } 813 ip6 = mtod(m, struct ip6_hdr *); 814 icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR, 815 (char *)&ip6->ip6_dst - (char *)ip6); 816 return IPPROTO_DONE; 817 } 818 819 tcp_input(m, *offp, proto); 820 return IPPROTO_DONE; 821 } 822 #endif 823 824 static void 825 tcp4_log_refused(const struct ip *ip, const struct tcphdr *th) 826 { 827 char src[INET_ADDRSTRLEN]; 828 char dst[INET_ADDRSTRLEN]; 829 830 if (ip) { 831 in_print(src, sizeof(src), &ip->ip_src); 832 in_print(dst, sizeof(dst), &ip->ip_dst); 833 } else { 834 strlcpy(src, "(unknown)", sizeof(src)); 835 strlcpy(dst, "(unknown)", sizeof(dst)); 836 } 837 log(LOG_INFO, 838 "Connection attempt to TCP %s:%d from %s:%d\n", 839 dst, ntohs(th->th_dport), 840 src, ntohs(th->th_sport)); 841 } 842 843 #ifdef INET6 844 static void 845 tcp6_log_refused(const struct ip6_hdr *ip6, const struct tcphdr *th) 846 { 847 char src[INET6_ADDRSTRLEN]; 848 char dst[INET6_ADDRSTRLEN]; 849 850 if (ip6) { 851 in6_print(src, sizeof(src), &ip6->ip6_src); 852 in6_print(dst, sizeof(dst), &ip6->ip6_dst); 853 } else { 854 strlcpy(src, "(unknown v6)", sizeof(src)); 855 strlcpy(dst, "(unknown v6)", sizeof(dst)); 856 } 857 log(LOG_INFO, 858 "Connection attempt to TCP [%s]:%d from [%s]:%d\n", 859 dst, ntohs(th->th_dport), 860 src, ntohs(th->th_sport)); 861 } 862 #endif 863 864 /* 865 * Checksum extended TCP header and data. 866 */ 867 int 868 tcp_input_checksum(int af, struct mbuf *m, const struct tcphdr *th, 869 int toff, int off, int tlen) 870 { 871 struct ifnet *rcvif; 872 int s; 873 874 /* 875 * XXX it's better to record and check if this mbuf is 876 * already checked. 877 */ 878 879 rcvif = m_get_rcvif(m, &s); 880 if (__predict_false(rcvif == NULL)) 881 goto badcsum; /* XXX */ 882 883 switch (af) { 884 case AF_INET: 885 switch (m->m_pkthdr.csum_flags & 886 ((rcvif->if_csum_flags_rx & M_CSUM_TCPv4) | 887 M_CSUM_TCP_UDP_BAD | M_CSUM_DATA)) { 888 case M_CSUM_TCPv4|M_CSUM_TCP_UDP_BAD: 889 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_bad); 890 goto badcsum; 891 892 case M_CSUM_TCPv4|M_CSUM_DATA: { 893 u_int32_t hw_csum = m->m_pkthdr.csum_data; 894 895 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_data); 896 if (m->m_pkthdr.csum_flags & M_CSUM_NO_PSEUDOHDR) { 897 const struct ip *ip = 898 mtod(m, const struct ip *); 899 900 hw_csum = in_cksum_phdr(ip->ip_src.s_addr, 901 ip->ip_dst.s_addr, 902 htons(hw_csum + tlen + off + IPPROTO_TCP)); 903 } 904 if ((hw_csum ^ 0xffff) != 0) 905 goto badcsum; 906 break; 907 } 908 909 case M_CSUM_TCPv4: 910 /* Checksum was okay. */ 911 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_ok); 912 break; 913 914 default: 915 /* 916 * Must compute it ourselves. Maybe skip checksum 917 * on loopback interfaces. 918 */ 919 if (__predict_true(!(rcvif->if_flags & IFF_LOOPBACK) || 920 tcp_do_loopback_cksum)) { 921 TCP_CSUM_COUNTER_INCR(&tcp_swcsum); 922 if (in4_cksum(m, IPPROTO_TCP, toff, 923 tlen + off) != 0) 924 goto badcsum; 925 } 926 break; 927 } 928 break; 929 930 #ifdef INET6 931 case AF_INET6: 932 switch (m->m_pkthdr.csum_flags & 933 ((rcvif->if_csum_flags_rx & M_CSUM_TCPv6) | 934 M_CSUM_TCP_UDP_BAD | M_CSUM_DATA)) { 935 case M_CSUM_TCPv6|M_CSUM_TCP_UDP_BAD: 936 TCP_CSUM_COUNTER_INCR(&tcp6_hwcsum_bad); 937 goto badcsum; 938 939 #if 0 /* notyet */ 940 case M_CSUM_TCPv6|M_CSUM_DATA: 941 #endif 942 943 case M_CSUM_TCPv6: 944 /* Checksum was okay. */ 945 TCP_CSUM_COUNTER_INCR(&tcp6_hwcsum_ok); 946 break; 947 948 default: 949 /* 950 * Must compute it ourselves. Maybe skip checksum 951 * on loopback interfaces. 952 */ 953 if (__predict_true((m->m_flags & M_LOOP) == 0 || 954 tcp_do_loopback_cksum)) { 955 TCP_CSUM_COUNTER_INCR(&tcp6_swcsum); 956 if (in6_cksum(m, IPPROTO_TCP, toff, 957 tlen + off) != 0) 958 goto badcsum; 959 } 960 } 961 break; 962 #endif /* INET6 */ 963 } 964 m_put_rcvif(rcvif, &s); 965 966 return 0; 967 968 badcsum: 969 m_put_rcvif(rcvif, &s); 970 TCP_STATINC(TCP_STAT_RCVBADSUM); 971 return -1; 972 } 973 974 /* 975 * When a packet arrives addressed to a vestigial tcpbp, we 976 * nevertheless have to respond to it per the spec. 977 * 978 * This code is duplicated from the one in tcp_input(). 979 */ 980 static void tcp_vtw_input(struct tcphdr *th, vestigial_inpcb_t *vp, 981 struct mbuf *m, int tlen) 982 { 983 int tiflags; 984 int todrop; 985 uint32_t t_flags = 0; 986 uint64_t *tcps; 987 988 tiflags = th->th_flags; 989 todrop = vp->rcv_nxt - th->th_seq; 990 991 if (todrop > 0) { 992 if (tiflags & TH_SYN) { 993 tiflags &= ~TH_SYN; 994 th->th_seq++; 995 tcp_urp_drop(th, 1, &tiflags); 996 todrop--; 997 } 998 if (todrop > tlen || 999 (todrop == tlen && (tiflags & TH_FIN) == 0)) { 1000 /* 1001 * Any valid FIN or RST must be to the left of the 1002 * window. At this point the FIN or RST must be a 1003 * duplicate or out of sequence; drop it. 1004 */ 1005 if (tiflags & TH_RST) 1006 goto drop; 1007 tiflags &= ~(TH_FIN|TH_RST); 1008 1009 /* 1010 * Send an ACK to resynchronize and drop any data. 1011 * But keep on processing for RST or ACK. 1012 */ 1013 t_flags |= TF_ACKNOW; 1014 todrop = tlen; 1015 tcps = TCP_STAT_GETREF(); 1016 tcps[TCP_STAT_RCVDUPPACK] += 1; 1017 tcps[TCP_STAT_RCVDUPBYTE] += todrop; 1018 TCP_STAT_PUTREF(); 1019 } else if ((tiflags & TH_RST) && 1020 th->th_seq != vp->rcv_nxt) { 1021 /* 1022 * Test for reset before adjusting the sequence 1023 * number for overlapping data. 1024 */ 1025 goto dropafterack_ratelim; 1026 } else { 1027 tcps = TCP_STAT_GETREF(); 1028 tcps[TCP_STAT_RCVPARTDUPPACK] += 1; 1029 tcps[TCP_STAT_RCVPARTDUPBYTE] += todrop; 1030 TCP_STAT_PUTREF(); 1031 } 1032 1033 // tcp_new_dsack(tp, th->th_seq, todrop); 1034 // hdroptlen += todrop; /*drop from head afterwards*/ 1035 1036 th->th_seq += todrop; 1037 tlen -= todrop; 1038 tcp_urp_drop(th, todrop, &tiflags); 1039 } 1040 1041 /* 1042 * If new data are received on a connection after the 1043 * user processes are gone, then RST the other end. 1044 */ 1045 if (tlen) { 1046 TCP_STATINC(TCP_STAT_RCVAFTERCLOSE); 1047 goto dropwithreset; 1048 } 1049 1050 /* 1051 * If segment ends after window, drop trailing data 1052 * (and PUSH and FIN); if nothing left, just ACK. 1053 */ 1054 todrop = (th->th_seq + tlen) - (vp->rcv_nxt + vp->rcv_wnd); 1055 1056 if (todrop > 0) { 1057 TCP_STATINC(TCP_STAT_RCVPACKAFTERWIN); 1058 if (todrop >= tlen) { 1059 /* 1060 * The segment actually starts after the window. 1061 * th->th_seq + tlen - vp->rcv_nxt - vp->rcv_wnd >= tlen 1062 * th->th_seq - vp->rcv_nxt - vp->rcv_wnd >= 0 1063 * th->th_seq >= vp->rcv_nxt + vp->rcv_wnd 1064 */ 1065 TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, tlen); 1066 1067 /* 1068 * If a new connection request is received 1069 * while in TIME_WAIT, drop the old connection 1070 * and start over if the sequence numbers 1071 * are above the previous ones. 1072 */ 1073 if ((tiflags & TH_SYN) && 1074 SEQ_GT(th->th_seq, vp->rcv_nxt)) { 1075 /* 1076 * We only support this in the !NOFDREF case, which 1077 * is to say: not here. 1078 */ 1079 goto dropwithreset; 1080 } 1081 1082 /* 1083 * If window is closed can only take segments at 1084 * window edge, and have to drop data and PUSH from 1085 * incoming segments. Continue processing, but 1086 * remember to ack. Otherwise, drop segment 1087 * and (if not RST) ack. 1088 */ 1089 if (vp->rcv_wnd == 0 && th->th_seq == vp->rcv_nxt) { 1090 t_flags |= TF_ACKNOW; 1091 TCP_STATINC(TCP_STAT_RCVWINPROBE); 1092 } else { 1093 goto dropafterack; 1094 } 1095 } else { 1096 TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, todrop); 1097 } 1098 m_adj(m, -todrop); 1099 tlen -= todrop; 1100 tiflags &= ~(TH_PUSH|TH_FIN); 1101 } 1102 1103 if (tiflags & TH_RST) { 1104 if (th->th_seq != vp->rcv_nxt) 1105 goto dropafterack_ratelim; 1106 1107 vtw_del(vp->ctl, vp->vtw); 1108 goto drop; 1109 } 1110 1111 /* 1112 * If the ACK bit is off we drop the segment and return. 1113 */ 1114 if ((tiflags & TH_ACK) == 0) { 1115 if (t_flags & TF_ACKNOW) 1116 goto dropafterack; 1117 goto drop; 1118 } 1119 1120 /* 1121 * In TIME_WAIT state the only thing that should arrive 1122 * is a retransmission of the remote FIN. Acknowledge 1123 * it and restart the finack timer. 1124 */ 1125 vtw_restart(vp); 1126 goto dropafterack; 1127 1128 dropafterack: 1129 /* 1130 * Generate an ACK dropping incoming segment if it occupies 1131 * sequence space, where the ACK reflects our state. 1132 */ 1133 if (tiflags & TH_RST) 1134 goto drop; 1135 goto dropafterack2; 1136 1137 dropafterack_ratelim: 1138 /* 1139 * We may want to rate-limit ACKs against SYN/RST attack. 1140 */ 1141 if (ppsratecheck(&tcp_ackdrop_ppslim_last, &tcp_ackdrop_ppslim_count, 1142 tcp_ackdrop_ppslim) == 0) { 1143 /* XXX stat */ 1144 goto drop; 1145 } 1146 /* ...fall into dropafterack2... */ 1147 1148 dropafterack2: 1149 (void)tcp_respond(0, m, m, th, th->th_seq + tlen, th->th_ack, TH_ACK); 1150 return; 1151 1152 dropwithreset: 1153 /* 1154 * Generate a RST, dropping incoming segment. 1155 * Make ACK acceptable to originator of segment. 1156 */ 1157 if (tiflags & TH_RST) 1158 goto drop; 1159 1160 if (tiflags & TH_ACK) { 1161 tcp_respond(0, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 1162 } else { 1163 if (tiflags & TH_SYN) 1164 ++tlen; 1165 (void)tcp_respond(0, m, m, th, th->th_seq + tlen, (tcp_seq)0, 1166 TH_RST|TH_ACK); 1167 } 1168 return; 1169 drop: 1170 m_freem(m); 1171 } 1172 1173 /* 1174 * TCP input routine, follows pages 65-76 of RFC 793 very closely. 1175 */ 1176 void 1177 tcp_input(struct mbuf *m, ...) 1178 { 1179 struct tcphdr *th; 1180 struct ip *ip; 1181 struct inpcb *inp; 1182 #ifdef INET6 1183 struct ip6_hdr *ip6; 1184 struct in6pcb *in6p; 1185 #endif 1186 u_int8_t *optp = NULL; 1187 int optlen = 0; 1188 int len, tlen, toff, hdroptlen = 0; 1189 struct tcpcb *tp = NULL; 1190 int tiflags; 1191 struct socket *so = NULL; 1192 int todrop, acked, ourfinisacked, needoutput = 0; 1193 bool dupseg; 1194 #ifdef TCP_DEBUG 1195 short ostate = 0; 1196 #endif 1197 u_long tiwin; 1198 struct tcp_opt_info opti; 1199 int off, iphlen; 1200 va_list ap; 1201 int af; /* af on the wire */ 1202 struct mbuf *tcp_saveti = NULL; 1203 uint32_t ts_rtt; 1204 uint8_t iptos; 1205 uint64_t *tcps; 1206 vestigial_inpcb_t vestige; 1207 1208 vestige.valid = 0; 1209 1210 MCLAIM(m, &tcp_rx_mowner); 1211 va_start(ap, m); 1212 toff = va_arg(ap, int); 1213 (void)va_arg(ap, int); /* ignore value, advance ap */ 1214 va_end(ap); 1215 1216 TCP_STATINC(TCP_STAT_RCVTOTAL); 1217 1218 memset(&opti, 0, sizeof(opti)); 1219 opti.ts_present = 0; 1220 opti.maxseg = 0; 1221 1222 /* 1223 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN. 1224 * 1225 * TCP is, by definition, unicast, so we reject all 1226 * multicast outright. 1227 * 1228 * Note, there are additional src/dst address checks in 1229 * the AF-specific code below. 1230 */ 1231 if (m->m_flags & (M_BCAST|M_MCAST)) { 1232 /* XXX stat */ 1233 goto drop; 1234 } 1235 #ifdef INET6 1236 if (m->m_flags & M_ANYCAST6) { 1237 /* XXX stat */ 1238 goto drop; 1239 } 1240 #endif 1241 1242 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, sizeof(struct tcphdr)); 1243 if (th == NULL) { 1244 TCP_STATINC(TCP_STAT_RCVSHORT); 1245 return; 1246 } 1247 1248 /* 1249 * Get IP and TCP header. 1250 * Note: IP leaves IP header in first mbuf. 1251 */ 1252 ip = mtod(m, struct ip *); 1253 switch (ip->ip_v) { 1254 case 4: 1255 #ifdef INET6 1256 ip6 = NULL; 1257 #endif 1258 af = AF_INET; 1259 iphlen = sizeof(struct ip); 1260 1261 if (IN_MULTICAST(ip->ip_dst.s_addr) || 1262 in_broadcast(ip->ip_dst, m_get_rcvif_NOMPSAFE(m))) 1263 goto drop; 1264 1265 /* We do the checksum after PCB lookup... */ 1266 len = ntohs(ip->ip_len); 1267 tlen = len - toff; 1268 iptos = ip->ip_tos; 1269 break; 1270 #ifdef INET6 1271 case 6: 1272 ip = NULL; 1273 iphlen = sizeof(struct ip6_hdr); 1274 af = AF_INET6; 1275 ip6 = mtod(m, struct ip6_hdr *); 1276 1277 /* 1278 * Be proactive about unspecified IPv6 address in source. 1279 * As we use all-zero to indicate unbounded/unconnected pcb, 1280 * unspecified IPv6 address can be used to confuse us. 1281 * 1282 * Note that packets with unspecified IPv6 destination is 1283 * already dropped in ip6_input. 1284 */ 1285 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 1286 /* XXX stat */ 1287 goto drop; 1288 } 1289 1290 /* 1291 * Make sure destination address is not multicast. 1292 * Source address checked in ip6_input(). 1293 */ 1294 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) { 1295 /* XXX stat */ 1296 goto drop; 1297 } 1298 1299 /* We do the checksum after PCB lookup... */ 1300 len = m->m_pkthdr.len; 1301 tlen = len - toff; 1302 iptos = (ntohl(ip6->ip6_flow) >> 20) & 0xff; 1303 break; 1304 #endif 1305 default: 1306 m_freem(m); 1307 return; 1308 } 1309 1310 /* 1311 * Enforce alignment requirements that are violated in 1312 * some cases, see kern/50766 for details. 1313 */ 1314 if (TCP_HDR_ALIGNED_P(th) == 0) { 1315 m = m_copyup(m, toff + sizeof(struct tcphdr), 0); 1316 if (m == NULL) { 1317 TCP_STATINC(TCP_STAT_RCVSHORT); 1318 return; 1319 } 1320 ip = mtod(m, struct ip *); 1321 #ifdef INET6 1322 ip6 = mtod(m, struct ip6_hdr *); 1323 #endif 1324 th = (struct tcphdr *)(mtod(m, char *) + toff); 1325 } 1326 KASSERT(TCP_HDR_ALIGNED_P(th)); 1327 1328 /* 1329 * Check that TCP offset makes sense, pull out TCP options and 1330 * adjust length. 1331 */ 1332 off = th->th_off << 2; 1333 if (off < sizeof(struct tcphdr) || off > tlen) { 1334 TCP_STATINC(TCP_STAT_RCVBADOFF); 1335 goto drop; 1336 } 1337 tlen -= off; 1338 1339 if (off > sizeof(struct tcphdr)) { 1340 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, off); 1341 if (th == NULL) { 1342 TCP_STATINC(TCP_STAT_RCVSHORT); 1343 return; 1344 } 1345 KASSERT(TCP_HDR_ALIGNED_P(th)); 1346 optlen = off - sizeof(struct tcphdr); 1347 optp = ((u_int8_t *)th) + sizeof(struct tcphdr); 1348 1349 /* 1350 * Do quick retrieval of timestamp options. 1351 * 1352 * If timestamp is the only option and it's formatted as 1353 * recommended in RFC 1323 appendix A, we quickly get the 1354 * values now and don't bother calling tcp_dooptions(), 1355 * etc. 1356 */ 1357 if ((optlen == TCPOLEN_TSTAMP_APPA || 1358 (optlen > TCPOLEN_TSTAMP_APPA && 1359 optp[TCPOLEN_TSTAMP_APPA] == TCPOPT_EOL)) && 1360 *(u_int32_t *)optp == htonl(TCPOPT_TSTAMP_HDR) && 1361 (th->th_flags & TH_SYN) == 0) { 1362 opti.ts_present = 1; 1363 opti.ts_val = ntohl(*(u_int32_t *)(optp + 4)); 1364 opti.ts_ecr = ntohl(*(u_int32_t *)(optp + 8)); 1365 optp = NULL; /* we've parsed the options */ 1366 } 1367 } 1368 tiflags = th->th_flags; 1369 1370 /* 1371 * Checksum extended TCP header and data 1372 */ 1373 if (tcp_input_checksum(af, m, th, toff, off, tlen)) 1374 goto badcsum; 1375 1376 /* 1377 * Locate pcb for segment. 1378 */ 1379 findpcb: 1380 inp = NULL; 1381 #ifdef INET6 1382 in6p = NULL; 1383 #endif 1384 switch (af) { 1385 case AF_INET: 1386 inp = in_pcblookup_connect(&tcbtable, ip->ip_src, th->th_sport, 1387 ip->ip_dst, th->th_dport, &vestige); 1388 if (inp == NULL && !vestige.valid) { 1389 TCP_STATINC(TCP_STAT_PCBHASHMISS); 1390 inp = in_pcblookup_bind(&tcbtable, ip->ip_dst, 1391 th->th_dport); 1392 } 1393 #ifdef INET6 1394 if (inp == NULL && !vestige.valid) { 1395 struct in6_addr s, d; 1396 1397 /* mapped addr case */ 1398 in6_in_2_v4mapin6(&ip->ip_src, &s); 1399 in6_in_2_v4mapin6(&ip->ip_dst, &d); 1400 in6p = in6_pcblookup_connect(&tcbtable, &s, 1401 th->th_sport, &d, th->th_dport, 0, &vestige); 1402 if (in6p == 0 && !vestige.valid) { 1403 TCP_STATINC(TCP_STAT_PCBHASHMISS); 1404 in6p = in6_pcblookup_bind(&tcbtable, &d, 1405 th->th_dport, 0); 1406 } 1407 } 1408 #endif 1409 #ifndef INET6 1410 if (inp == NULL && !vestige.valid) 1411 #else 1412 if (inp == NULL && in6p == NULL && !vestige.valid) 1413 #endif 1414 { 1415 TCP_STATINC(TCP_STAT_NOPORT); 1416 if (tcp_log_refused && 1417 (tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) { 1418 tcp4_log_refused(ip, th); 1419 } 1420 tcp_fields_to_host(th); 1421 goto dropwithreset_ratelim; 1422 } 1423 #if defined(IPSEC) 1424 if (ipsec_used) { 1425 if (inp && ipsec_in_reject(m, inp)) { 1426 goto drop; 1427 } 1428 #ifdef INET6 1429 else if (in6p && ipsec_in_reject(m, in6p)) { 1430 goto drop; 1431 } 1432 #endif 1433 } 1434 #endif /*IPSEC*/ 1435 break; 1436 #ifdef INET6 1437 case AF_INET6: 1438 { 1439 int faith; 1440 1441 #if defined(NFAITH) && NFAITH > 0 1442 faith = faithprefix(&ip6->ip6_dst); 1443 #else 1444 faith = 0; 1445 #endif 1446 in6p = in6_pcblookup_connect(&tcbtable, &ip6->ip6_src, 1447 th->th_sport, &ip6->ip6_dst, th->th_dport, faith, &vestige); 1448 if (!in6p && !vestige.valid) { 1449 TCP_STATINC(TCP_STAT_PCBHASHMISS); 1450 in6p = in6_pcblookup_bind(&tcbtable, &ip6->ip6_dst, 1451 th->th_dport, faith); 1452 } 1453 if (!in6p && !vestige.valid) { 1454 TCP_STATINC(TCP_STAT_NOPORT); 1455 if (tcp_log_refused && 1456 (tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) { 1457 tcp6_log_refused(ip6, th); 1458 } 1459 tcp_fields_to_host(th); 1460 goto dropwithreset_ratelim; 1461 } 1462 #if defined(IPSEC) 1463 if (ipsec_used && in6p && ipsec_in_reject(m, in6p)) { 1464 goto drop; 1465 } 1466 #endif 1467 break; 1468 } 1469 #endif 1470 } 1471 1472 tcp_fields_to_host(th); 1473 1474 /* 1475 * If the state is CLOSED (i.e., TCB does not exist) then 1476 * all data in the incoming segment is discarded. 1477 * If the TCB exists but is in CLOSED state, it is embryonic, 1478 * but should either do a listen or a connect soon. 1479 */ 1480 tp = NULL; 1481 so = NULL; 1482 if (inp) { 1483 /* Check the minimum TTL for socket. */ 1484 if (ip->ip_ttl < inp->inp_ip_minttl) 1485 goto drop; 1486 1487 tp = intotcpcb(inp); 1488 so = inp->inp_socket; 1489 } 1490 #ifdef INET6 1491 else if (in6p) { 1492 tp = in6totcpcb(in6p); 1493 so = in6p->in6p_socket; 1494 } 1495 #endif 1496 else if (vestige.valid) { 1497 /* We do not support the resurrection of vtw tcpcps. */ 1498 tcp_vtw_input(th, &vestige, m, tlen); 1499 m = NULL; 1500 goto drop; 1501 } 1502 1503 if (tp == NULL) 1504 goto dropwithreset_ratelim; 1505 if (tp->t_state == TCPS_CLOSED) 1506 goto drop; 1507 1508 KASSERT(so->so_lock == softnet_lock); 1509 KASSERT(solocked(so)); 1510 1511 /* Unscale the window into a 32-bit value. */ 1512 if ((tiflags & TH_SYN) == 0) 1513 tiwin = th->th_win << tp->snd_scale; 1514 else 1515 tiwin = th->th_win; 1516 1517 #ifdef INET6 1518 /* save packet options if user wanted */ 1519 if (in6p && (in6p->in6p_flags & IN6P_CONTROLOPTS)) { 1520 if (in6p->in6p_options) { 1521 m_freem(in6p->in6p_options); 1522 in6p->in6p_options = NULL; 1523 } 1524 KASSERT(ip6 != NULL); 1525 ip6_savecontrol(in6p, &in6p->in6p_options, ip6, m); 1526 } 1527 #endif 1528 1529 if (so->so_options & SO_DEBUG) { 1530 #ifdef TCP_DEBUG 1531 ostate = tp->t_state; 1532 #endif 1533 1534 tcp_saveti = NULL; 1535 if (iphlen + sizeof(struct tcphdr) > MHLEN) 1536 goto nosave; 1537 1538 if (m->m_len > iphlen && (m->m_flags & M_EXT) == 0) { 1539 tcp_saveti = m_copym(m, 0, iphlen, M_DONTWAIT); 1540 if (tcp_saveti == NULL) 1541 goto nosave; 1542 } else { 1543 MGETHDR(tcp_saveti, M_DONTWAIT, MT_HEADER); 1544 if (tcp_saveti == NULL) 1545 goto nosave; 1546 MCLAIM(m, &tcp_mowner); 1547 tcp_saveti->m_len = iphlen; 1548 m_copydata(m, 0, iphlen, 1549 mtod(tcp_saveti, void *)); 1550 } 1551 1552 if (M_TRAILINGSPACE(tcp_saveti) < sizeof(struct tcphdr)) { 1553 m_freem(tcp_saveti); 1554 tcp_saveti = NULL; 1555 } else { 1556 tcp_saveti->m_len += sizeof(struct tcphdr); 1557 memcpy(mtod(tcp_saveti, char *) + iphlen, th, 1558 sizeof(struct tcphdr)); 1559 } 1560 nosave:; 1561 } 1562 1563 if (so->so_options & SO_ACCEPTCONN) { 1564 union syn_cache_sa src; 1565 union syn_cache_sa dst; 1566 1567 KASSERT(tp->t_state == TCPS_LISTEN); 1568 1569 memset(&src, 0, sizeof(src)); 1570 memset(&dst, 0, sizeof(dst)); 1571 switch (af) { 1572 case AF_INET: 1573 src.sin.sin_len = sizeof(struct sockaddr_in); 1574 src.sin.sin_family = AF_INET; 1575 src.sin.sin_addr = ip->ip_src; 1576 src.sin.sin_port = th->th_sport; 1577 1578 dst.sin.sin_len = sizeof(struct sockaddr_in); 1579 dst.sin.sin_family = AF_INET; 1580 dst.sin.sin_addr = ip->ip_dst; 1581 dst.sin.sin_port = th->th_dport; 1582 break; 1583 #ifdef INET6 1584 case AF_INET6: 1585 src.sin6.sin6_len = sizeof(struct sockaddr_in6); 1586 src.sin6.sin6_family = AF_INET6; 1587 src.sin6.sin6_addr = ip6->ip6_src; 1588 src.sin6.sin6_port = th->th_sport; 1589 1590 dst.sin6.sin6_len = sizeof(struct sockaddr_in6); 1591 dst.sin6.sin6_family = AF_INET6; 1592 dst.sin6.sin6_addr = ip6->ip6_dst; 1593 dst.sin6.sin6_port = th->th_dport; 1594 break; 1595 #endif 1596 } 1597 1598 if ((tiflags & (TH_RST|TH_ACK|TH_SYN)) != TH_SYN) { 1599 if (tiflags & TH_RST) { 1600 syn_cache_reset(&src.sa, &dst.sa, th); 1601 } else if ((tiflags & (TH_ACK|TH_SYN)) == 1602 (TH_ACK|TH_SYN)) { 1603 /* 1604 * Received a SYN,ACK. This should never 1605 * happen while we are in LISTEN. Send an RST. 1606 */ 1607 goto badsyn; 1608 } else if (tiflags & TH_ACK) { 1609 so = syn_cache_get(&src.sa, &dst.sa, th, so, m); 1610 if (so == NULL) { 1611 /* 1612 * We don't have a SYN for this ACK; 1613 * send an RST. 1614 */ 1615 goto badsyn; 1616 } else if (so == (struct socket *)(-1)) { 1617 /* 1618 * We were unable to create the 1619 * connection. If the 3-way handshake 1620 * was completed, and RST has been 1621 * sent to the peer. Since the mbuf 1622 * might be in use for the reply, do 1623 * not free it. 1624 */ 1625 m = NULL; 1626 } else { 1627 /* 1628 * We have created a full-blown 1629 * connection. 1630 */ 1631 tp = NULL; 1632 inp = NULL; 1633 #ifdef INET6 1634 in6p = NULL; 1635 #endif 1636 switch (so->so_proto->pr_domain->dom_family) { 1637 case AF_INET: 1638 inp = sotoinpcb(so); 1639 tp = intotcpcb(inp); 1640 break; 1641 #ifdef INET6 1642 case AF_INET6: 1643 in6p = sotoin6pcb(so); 1644 tp = in6totcpcb(in6p); 1645 break; 1646 #endif 1647 } 1648 if (tp == NULL) 1649 goto badsyn; /*XXX*/ 1650 tiwin <<= tp->snd_scale; 1651 goto after_listen; 1652 } 1653 } else { 1654 /* 1655 * None of RST, SYN or ACK was set. 1656 * This is an invalid packet for a 1657 * TCB in LISTEN state. Send a RST. 1658 */ 1659 goto badsyn; 1660 } 1661 } else { 1662 /* 1663 * Received a SYN. 1664 */ 1665 1666 #ifdef INET6 1667 /* 1668 * If deprecated address is forbidden, we do 1669 * not accept SYN to deprecated interface 1670 * address to prevent any new inbound 1671 * connection from getting established. 1672 * When we do not accept SYN, we send a TCP 1673 * RST, with deprecated source address (instead 1674 * of dropping it). We compromise it as it is 1675 * much better for peer to send a RST, and 1676 * RST will be the final packet for the 1677 * exchange. 1678 * 1679 * If we do not forbid deprecated addresses, we 1680 * accept the SYN packet. RFC2462 does not 1681 * suggest dropping SYN in this case. 1682 * If we decipher RFC2462 5.5.4, it says like 1683 * this: 1684 * 1. use of deprecated addr with existing 1685 * communication is okay - "SHOULD continue 1686 * to be used" 1687 * 2. use of it with new communication: 1688 * (2a) "SHOULD NOT be used if alternate 1689 * address with sufficient scope is 1690 * available" 1691 * (2b) nothing mentioned otherwise. 1692 * Here we fall into (2b) case as we have no 1693 * choice in our source address selection - we 1694 * must obey the peer. 1695 * 1696 * The wording in RFC2462 is confusing, and 1697 * there are multiple description text for 1698 * deprecated address handling - worse, they 1699 * are not exactly the same. I believe 5.5.4 1700 * is the best one, so we follow 5.5.4. 1701 */ 1702 if (af == AF_INET6 && !ip6_use_deprecated) { 1703 struct in6_ifaddr *ia6; 1704 int s; 1705 struct ifnet *rcvif = m_get_rcvif(m, &s); 1706 if (rcvif == NULL) 1707 goto dropwithreset; /* XXX */ 1708 if ((ia6 = in6ifa_ifpwithaddr(rcvif, 1709 &ip6->ip6_dst)) && 1710 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) { 1711 tp = NULL; 1712 m_put_rcvif(rcvif, &s); 1713 goto dropwithreset; 1714 } 1715 m_put_rcvif(rcvif, &s); 1716 } 1717 #endif 1718 1719 /* 1720 * LISTEN socket received a SYN from itself? This 1721 * can't possibly be valid; drop the packet. 1722 */ 1723 if (th->th_sport == th->th_dport) { 1724 int eq = 0; 1725 1726 switch (af) { 1727 case AF_INET: 1728 eq = in_hosteq(ip->ip_src, ip->ip_dst); 1729 break; 1730 #ifdef INET6 1731 case AF_INET6: 1732 eq = IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, 1733 &ip6->ip6_dst); 1734 break; 1735 #endif 1736 } 1737 if (eq) { 1738 TCP_STATINC(TCP_STAT_BADSYN); 1739 goto drop; 1740 } 1741 } 1742 1743 /* 1744 * SYN looks ok; create compressed TCP 1745 * state for it. 1746 */ 1747 if (so->so_qlen <= so->so_qlimit && 1748 syn_cache_add(&src.sa, &dst.sa, th, toff, 1749 so, m, optp, optlen, &opti)) 1750 m = NULL; 1751 } 1752 1753 goto drop; 1754 } 1755 1756 after_listen: 1757 /* 1758 * From here on, we're dealing with !LISTEN. 1759 */ 1760 KASSERT(tp->t_state != TCPS_LISTEN); 1761 1762 /* 1763 * Segment received on connection. 1764 * Reset idle time and keep-alive timer. 1765 */ 1766 tp->t_rcvtime = tcp_now; 1767 if (TCPS_HAVEESTABLISHED(tp->t_state)) 1768 TCP_TIMER_ARM(tp, TCPT_KEEP, tp->t_keepidle); 1769 1770 /* 1771 * Process options. 1772 */ 1773 #ifdef TCP_SIGNATURE 1774 if (optp || (tp->t_flags & TF_SIGNATURE)) 1775 #else 1776 if (optp) 1777 #endif 1778 if (tcp_dooptions(tp, optp, optlen, th, m, toff, &opti) < 0) 1779 goto drop; 1780 1781 if (TCP_SACK_ENABLED(tp)) { 1782 tcp_del_sackholes(tp, th); 1783 } 1784 1785 if (TCP_ECN_ALLOWED(tp)) { 1786 if (tiflags & TH_CWR) { 1787 tp->t_flags &= ~TF_ECN_SND_ECE; 1788 } 1789 switch (iptos & IPTOS_ECN_MASK) { 1790 case IPTOS_ECN_CE: 1791 tp->t_flags |= TF_ECN_SND_ECE; 1792 TCP_STATINC(TCP_STAT_ECN_CE); 1793 break; 1794 case IPTOS_ECN_ECT0: 1795 TCP_STATINC(TCP_STAT_ECN_ECT); 1796 break; 1797 case IPTOS_ECN_ECT1: 1798 /* XXX: ignore for now -- rpaulo */ 1799 break; 1800 } 1801 /* 1802 * Congestion experienced. 1803 * Ignore if we are already trying to recover. 1804 */ 1805 if ((tiflags & TH_ECE) && SEQ_GEQ(tp->snd_una, tp->snd_recover)) 1806 tp->t_congctl->cong_exp(tp); 1807 } 1808 1809 if (opti.ts_present && opti.ts_ecr) { 1810 /* 1811 * Calculate the RTT from the returned time stamp and the 1812 * connection's time base. If the time stamp is later than 1813 * the current time, or is extremely old, fall back to non-1323 1814 * RTT calculation. Since ts_rtt is unsigned, we can test both 1815 * at the same time. 1816 * 1817 * Note that ts_rtt is in units of slow ticks (500 1818 * ms). Since most earthbound RTTs are < 500 ms, 1819 * observed values will have large quantization noise. 1820 * Our smoothed RTT is then the fraction of observed 1821 * samples that are 1 tick instead of 0 (times 500 1822 * ms). 1823 * 1824 * ts_rtt is increased by 1 to denote a valid sample, 1825 * with 0 indicating an invalid measurement. This 1826 * extra 1 must be removed when ts_rtt is used, or 1827 * else an an erroneous extra 500 ms will result. 1828 */ 1829 ts_rtt = TCP_TIMESTAMP(tp) - opti.ts_ecr + 1; 1830 if (ts_rtt > TCP_PAWS_IDLE) 1831 ts_rtt = 0; 1832 } else { 1833 ts_rtt = 0; 1834 } 1835 1836 /* 1837 * Fast path: check for the two common cases of a uni-directional 1838 * data transfer. If: 1839 * o We are in the ESTABLISHED state, and 1840 * o The packet has no control flags, and 1841 * o The packet is in-sequence, and 1842 * o The window didn't change, and 1843 * o We are not retransmitting 1844 * It's a candidate. 1845 * 1846 * If the length (tlen) is zero and the ack moved forward, we're 1847 * the sender side of the transfer. Just free the data acked and 1848 * wake any higher level process that was blocked waiting for 1849 * space. 1850 * 1851 * If the length is non-zero and the ack didn't move, we're the 1852 * receiver side. If we're getting packets in-order (the reassembly 1853 * queue is empty), add the data to the socket buffer and note 1854 * that we need a delayed ack. 1855 */ 1856 if (tp->t_state == TCPS_ESTABLISHED && 1857 (tiflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ECE|TH_CWR|TH_ACK)) 1858 == TH_ACK && 1859 (!opti.ts_present || TSTMP_GEQ(opti.ts_val, tp->ts_recent)) && 1860 th->th_seq == tp->rcv_nxt && 1861 tiwin && tiwin == tp->snd_wnd && 1862 tp->snd_nxt == tp->snd_max) { 1863 1864 /* 1865 * If last ACK falls within this segment's sequence numbers, 1866 * record the timestamp. 1867 * NOTE that the test is modified according to the latest 1868 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 1869 * 1870 * note that we already know 1871 * TSTMP_GEQ(opti.ts_val, tp->ts_recent) 1872 */ 1873 if (opti.ts_present && SEQ_LEQ(th->th_seq, tp->last_ack_sent)) { 1874 tp->ts_recent_age = tcp_now; 1875 tp->ts_recent = opti.ts_val; 1876 } 1877 1878 if (tlen == 0) { 1879 /* Ack prediction. */ 1880 if (SEQ_GT(th->th_ack, tp->snd_una) && 1881 SEQ_LEQ(th->th_ack, tp->snd_max) && 1882 tp->snd_cwnd >= tp->snd_wnd && 1883 tp->t_partialacks < 0) { 1884 /* 1885 * this is a pure ack for outstanding data. 1886 */ 1887 if (ts_rtt) 1888 tcp_xmit_timer(tp, ts_rtt - 1); 1889 else if (tp->t_rtttime && 1890 SEQ_GT(th->th_ack, tp->t_rtseq)) 1891 tcp_xmit_timer(tp, 1892 tcp_now - tp->t_rtttime); 1893 acked = th->th_ack - tp->snd_una; 1894 tcps = TCP_STAT_GETREF(); 1895 tcps[TCP_STAT_PREDACK]++; 1896 tcps[TCP_STAT_RCVACKPACK]++; 1897 tcps[TCP_STAT_RCVACKBYTE] += acked; 1898 TCP_STAT_PUTREF(); 1899 nd6_hint(tp); 1900 1901 if (acked > (tp->t_lastoff - tp->t_inoff)) 1902 tp->t_lastm = NULL; 1903 sbdrop(&so->so_snd, acked); 1904 tp->t_lastoff -= acked; 1905 1906 icmp_check(tp, th, acked); 1907 1908 tp->snd_una = th->th_ack; 1909 tp->snd_fack = tp->snd_una; 1910 if (SEQ_LT(tp->snd_high, tp->snd_una)) 1911 tp->snd_high = tp->snd_una; 1912 m_freem(m); 1913 1914 /* 1915 * If all outstanding data are acked, stop 1916 * retransmit timer, otherwise restart timer 1917 * using current (possibly backed-off) value. 1918 * If process is waiting for space, 1919 * wakeup/selnotify/signal. If data 1920 * are ready to send, let tcp_output 1921 * decide between more output or persist. 1922 */ 1923 if (tp->snd_una == tp->snd_max) 1924 TCP_TIMER_DISARM(tp, TCPT_REXMT); 1925 else if (TCP_TIMER_ISARMED(tp, 1926 TCPT_PERSIST) == 0) 1927 TCP_TIMER_ARM(tp, TCPT_REXMT, 1928 tp->t_rxtcur); 1929 1930 sowwakeup(so); 1931 if (so->so_snd.sb_cc) { 1932 KERNEL_LOCK(1, NULL); 1933 (void)tcp_output(tp); 1934 KERNEL_UNLOCK_ONE(NULL); 1935 } 1936 if (tcp_saveti) 1937 m_freem(tcp_saveti); 1938 return; 1939 } 1940 } else if (th->th_ack == tp->snd_una && 1941 TAILQ_FIRST(&tp->segq) == NULL && 1942 tlen <= sbspace(&so->so_rcv)) { 1943 int newsize = 0; 1944 1945 /* 1946 * this is a pure, in-sequence data packet 1947 * with nothing on the reassembly queue and 1948 * we have enough buffer space to take it. 1949 */ 1950 tp->rcv_nxt += tlen; 1951 tcps = TCP_STAT_GETREF(); 1952 tcps[TCP_STAT_PREDDAT]++; 1953 tcps[TCP_STAT_RCVPACK]++; 1954 tcps[TCP_STAT_RCVBYTE] += tlen; 1955 TCP_STAT_PUTREF(); 1956 nd6_hint(tp); 1957 1958 /* 1959 * Automatic sizing enables the performance of large buffers 1960 * and most of the efficiency of small ones by only allocating 1961 * space when it is needed. 1962 * 1963 * On the receive side the socket buffer memory is only rarely 1964 * used to any significant extent. This allows us to be much 1965 * more aggressive in scaling the receive socket buffer. For 1966 * the case that the buffer space is actually used to a large 1967 * extent and we run out of kernel memory we can simply drop 1968 * the new segments; TCP on the sender will just retransmit it 1969 * later. Setting the buffer size too big may only consume too 1970 * much kernel memory if the application doesn't read() from 1971 * the socket or packet loss or reordering makes use of the 1972 * reassembly queue. 1973 * 1974 * The criteria to step up the receive buffer one notch are: 1975 * 1. the number of bytes received during the time it takes 1976 * one timestamp to be reflected back to us (the RTT); 1977 * 2. received bytes per RTT is within seven eighth of the 1978 * current socket buffer size; 1979 * 3. receive buffer size has not hit maximal automatic size; 1980 * 1981 * This algorithm does one step per RTT at most and only if 1982 * we receive a bulk stream w/o packet losses or reorderings. 1983 * Shrinking the buffer during idle times is not necessary as 1984 * it doesn't consume any memory when idle. 1985 * 1986 * TODO: Only step up if the application is actually serving 1987 * the buffer to better manage the socket buffer resources. 1988 */ 1989 if (tcp_do_autorcvbuf && 1990 opti.ts_ecr && 1991 (so->so_rcv.sb_flags & SB_AUTOSIZE)) { 1992 if (opti.ts_ecr > tp->rfbuf_ts && 1993 opti.ts_ecr - tp->rfbuf_ts < PR_SLOWHZ) { 1994 if (tp->rfbuf_cnt > 1995 (so->so_rcv.sb_hiwat / 8 * 7) && 1996 so->so_rcv.sb_hiwat < 1997 tcp_autorcvbuf_max) { 1998 newsize = 1999 min(so->so_rcv.sb_hiwat + 2000 tcp_autorcvbuf_inc, 2001 tcp_autorcvbuf_max); 2002 } 2003 /* Start over with next RTT. */ 2004 tp->rfbuf_ts = 0; 2005 tp->rfbuf_cnt = 0; 2006 } else 2007 tp->rfbuf_cnt += tlen; /* add up */ 2008 } 2009 2010 /* 2011 * Drop TCP, IP headers and TCP options then add data 2012 * to socket buffer. 2013 */ 2014 if (so->so_state & SS_CANTRCVMORE) { 2015 m_freem(m); 2016 } else { 2017 /* 2018 * Set new socket buffer size. 2019 * Give up when limit is reached. 2020 */ 2021 if (newsize) 2022 if (!sbreserve(&so->so_rcv, 2023 newsize, so)) 2024 so->so_rcv.sb_flags &= ~SB_AUTOSIZE; 2025 m_adj(m, toff + off); 2026 sbappendstream(&so->so_rcv, m); 2027 } 2028 sorwakeup(so); 2029 tcp_setup_ack(tp, th); 2030 if (tp->t_flags & TF_ACKNOW) { 2031 KERNEL_LOCK(1, NULL); 2032 (void)tcp_output(tp); 2033 KERNEL_UNLOCK_ONE(NULL); 2034 } 2035 if (tcp_saveti) 2036 m_freem(tcp_saveti); 2037 return; 2038 } 2039 } 2040 2041 /* 2042 * Compute mbuf offset to TCP data segment. 2043 */ 2044 hdroptlen = toff + off; 2045 2046 /* 2047 * Calculate amount of space in receive window. Receive window is 2048 * amount of space in rcv queue, but not less than advertised 2049 * window. 2050 */ 2051 { 2052 int win; 2053 win = sbspace(&so->so_rcv); 2054 if (win < 0) 2055 win = 0; 2056 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 2057 } 2058 2059 /* Reset receive buffer auto scaling when not in bulk receive mode. */ 2060 tp->rfbuf_ts = 0; 2061 tp->rfbuf_cnt = 0; 2062 2063 switch (tp->t_state) { 2064 /* 2065 * If the state is SYN_SENT: 2066 * if seg contains an ACK, but not for our SYN, drop the input. 2067 * if seg contains a RST, then drop the connection. 2068 * if seg does not contain SYN, then drop it. 2069 * Otherwise this is an acceptable SYN segment 2070 * initialize tp->rcv_nxt and tp->irs 2071 * if seg contains ack then advance tp->snd_una 2072 * if seg contains a ECE and ECN support is enabled, the stream 2073 * is ECN capable. 2074 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 2075 * arrange for segment to be acked (eventually) 2076 * continue processing rest of data/controls, beginning with URG 2077 */ 2078 case TCPS_SYN_SENT: 2079 if ((tiflags & TH_ACK) && 2080 (SEQ_LEQ(th->th_ack, tp->iss) || 2081 SEQ_GT(th->th_ack, tp->snd_max))) 2082 goto dropwithreset; 2083 if (tiflags & TH_RST) { 2084 if (tiflags & TH_ACK) 2085 tp = tcp_drop(tp, ECONNREFUSED); 2086 goto drop; 2087 } 2088 if ((tiflags & TH_SYN) == 0) 2089 goto drop; 2090 if (tiflags & TH_ACK) { 2091 tp->snd_una = th->th_ack; 2092 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2093 tp->snd_nxt = tp->snd_una; 2094 if (SEQ_LT(tp->snd_high, tp->snd_una)) 2095 tp->snd_high = tp->snd_una; 2096 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2097 2098 if ((tiflags & TH_ECE) && tcp_do_ecn) { 2099 tp->t_flags |= TF_ECN_PERMIT; 2100 TCP_STATINC(TCP_STAT_ECN_SHS); 2101 } 2102 } 2103 tp->irs = th->th_seq; 2104 tcp_rcvseqinit(tp); 2105 tp->t_flags |= TF_ACKNOW; 2106 tcp_mss_from_peer(tp, opti.maxseg); 2107 2108 /* 2109 * Initialize the initial congestion window. If we 2110 * had to retransmit the SYN, we must initialize cwnd 2111 * to 1 segment (i.e. the Loss Window). 2112 */ 2113 if (tp->t_flags & TF_SYN_REXMT) 2114 tp->snd_cwnd = tp->t_peermss; 2115 else { 2116 int ss = tcp_init_win; 2117 if (inp != NULL && in_localaddr(inp->inp_faddr)) 2118 ss = tcp_init_win_local; 2119 #ifdef INET6 2120 if (in6p != NULL && in6_localaddr(&in6p->in6p_faddr)) 2121 ss = tcp_init_win_local; 2122 #endif 2123 tp->snd_cwnd = TCP_INITIAL_WINDOW(ss, tp->t_peermss); 2124 } 2125 2126 tcp_rmx_rtt(tp); 2127 if (tiflags & TH_ACK) { 2128 TCP_STATINC(TCP_STAT_CONNECTS); 2129 /* 2130 * move tcp_established before soisconnected 2131 * because upcall handler can drive tcp_output 2132 * functionality. 2133 * XXX we might call soisconnected at the end of 2134 * all processing 2135 */ 2136 tcp_established(tp); 2137 soisconnected(so); 2138 /* Do window scaling on this connection? */ 2139 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2140 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2141 tp->snd_scale = tp->requested_s_scale; 2142 tp->rcv_scale = tp->request_r_scale; 2143 } 2144 TCP_REASS_LOCK(tp); 2145 (void)tcp_reass(tp, NULL, NULL, tlen); 2146 /* 2147 * if we didn't have to retransmit the SYN, 2148 * use its rtt as our initial srtt & rtt var. 2149 */ 2150 if (tp->t_rtttime) 2151 tcp_xmit_timer(tp, tcp_now - tp->t_rtttime); 2152 } else { 2153 tp->t_state = TCPS_SYN_RECEIVED; 2154 } 2155 2156 /* 2157 * Advance th->th_seq to correspond to first data byte. 2158 * If data, trim to stay within window, 2159 * dropping FIN if necessary. 2160 */ 2161 th->th_seq++; 2162 if (tlen > tp->rcv_wnd) { 2163 todrop = tlen - tp->rcv_wnd; 2164 m_adj(m, -todrop); 2165 tlen = tp->rcv_wnd; 2166 tiflags &= ~TH_FIN; 2167 tcps = TCP_STAT_GETREF(); 2168 tcps[TCP_STAT_RCVPACKAFTERWIN]++; 2169 tcps[TCP_STAT_RCVBYTEAFTERWIN] += todrop; 2170 TCP_STAT_PUTREF(); 2171 } 2172 tp->snd_wl1 = th->th_seq - 1; 2173 tp->rcv_up = th->th_seq; 2174 goto step6; 2175 2176 /* 2177 * If the state is SYN_RECEIVED: 2178 * If seg contains an ACK, but not for our SYN, drop the input 2179 * and generate an RST. See page 36, rfc793 2180 */ 2181 case TCPS_SYN_RECEIVED: 2182 if ((tiflags & TH_ACK) && 2183 (SEQ_LEQ(th->th_ack, tp->iss) || 2184 SEQ_GT(th->th_ack, tp->snd_max))) 2185 goto dropwithreset; 2186 break; 2187 } 2188 2189 /* 2190 * From here on, we're dealing with !LISTEN and !SYN_SENT. 2191 */ 2192 KASSERT(tp->t_state != TCPS_LISTEN && 2193 tp->t_state != TCPS_SYN_SENT); 2194 2195 /* 2196 * RFC1323 PAWS: if we have a timestamp reply on this segment and 2197 * it's less than ts_recent, drop it. 2198 */ 2199 if (opti.ts_present && (tiflags & TH_RST) == 0 && tp->ts_recent && 2200 TSTMP_LT(opti.ts_val, tp->ts_recent)) { 2201 /* Check to see if ts_recent is over 24 days old. */ 2202 if (tcp_now - tp->ts_recent_age > TCP_PAWS_IDLE) { 2203 /* 2204 * Invalidate ts_recent. If this segment updates 2205 * ts_recent, the age will be reset later and ts_recent 2206 * will get a valid value. If it does not, setting 2207 * ts_recent to zero will at least satisfy the 2208 * requirement that zero be placed in the timestamp 2209 * echo reply when ts_recent isn't valid. The 2210 * age isn't reset until we get a valid ts_recent 2211 * because we don't want out-of-order segments to be 2212 * dropped when ts_recent is old. 2213 */ 2214 tp->ts_recent = 0; 2215 } else { 2216 tcps = TCP_STAT_GETREF(); 2217 tcps[TCP_STAT_RCVDUPPACK]++; 2218 tcps[TCP_STAT_RCVDUPBYTE] += tlen; 2219 tcps[TCP_STAT_PAWSDROP]++; 2220 TCP_STAT_PUTREF(); 2221 tcp_new_dsack(tp, th->th_seq, tlen); 2222 goto dropafterack; 2223 } 2224 } 2225 2226 /* 2227 * Check that at least some bytes of the segment are within the 2228 * receive window. If segment begins before rcv_nxt, drop leading 2229 * data (and SYN); if nothing left, just ack. 2230 */ 2231 todrop = tp->rcv_nxt - th->th_seq; 2232 dupseg = false; 2233 if (todrop > 0) { 2234 if (tiflags & TH_SYN) { 2235 tiflags &= ~TH_SYN; 2236 th->th_seq++; 2237 tcp_urp_drop(th, 1, &tiflags); 2238 todrop--; 2239 } 2240 if (todrop > tlen || 2241 (todrop == tlen && (tiflags & TH_FIN) == 0)) { 2242 /* 2243 * Any valid FIN or RST must be to the left of the 2244 * window. At this point the FIN or RST must be a 2245 * duplicate or out of sequence; drop it. 2246 */ 2247 if (tiflags & TH_RST) 2248 goto drop; 2249 tiflags &= ~(TH_FIN|TH_RST); 2250 2251 /* 2252 * Send an ACK to resynchronize and drop any data. 2253 * But keep on processing for RST or ACK. 2254 */ 2255 tp->t_flags |= TF_ACKNOW; 2256 todrop = tlen; 2257 dupseg = true; 2258 tcps = TCP_STAT_GETREF(); 2259 tcps[TCP_STAT_RCVDUPPACK]++; 2260 tcps[TCP_STAT_RCVDUPBYTE] += todrop; 2261 TCP_STAT_PUTREF(); 2262 } else if ((tiflags & TH_RST) && th->th_seq != tp->rcv_nxt) { 2263 /* 2264 * Test for reset before adjusting the sequence 2265 * number for overlapping data. 2266 */ 2267 goto dropafterack_ratelim; 2268 } else { 2269 tcps = TCP_STAT_GETREF(); 2270 tcps[TCP_STAT_RCVPARTDUPPACK]++; 2271 tcps[TCP_STAT_RCVPARTDUPBYTE] += todrop; 2272 TCP_STAT_PUTREF(); 2273 } 2274 tcp_new_dsack(tp, th->th_seq, todrop); 2275 hdroptlen += todrop; /* drop from head afterwards (m_adj) */ 2276 th->th_seq += todrop; 2277 tlen -= todrop; 2278 tcp_urp_drop(th, todrop, &tiflags); 2279 } 2280 2281 /* 2282 * If new data is received on a connection after the user processes 2283 * are gone, then RST the other end. 2284 */ 2285 if ((so->so_state & SS_NOFDREF) && 2286 tp->t_state > TCPS_CLOSE_WAIT && tlen) { 2287 tp = tcp_close(tp); 2288 TCP_STATINC(TCP_STAT_RCVAFTERCLOSE); 2289 goto dropwithreset; 2290 } 2291 2292 /* 2293 * If the segment ends after the window, drop trailing data (and 2294 * PUSH and FIN); if nothing left, just ACK. 2295 */ 2296 todrop = (th->th_seq + tlen) - (tp->rcv_nxt + tp->rcv_wnd); 2297 if (todrop > 0) { 2298 TCP_STATINC(TCP_STAT_RCVPACKAFTERWIN); 2299 if (todrop >= tlen) { 2300 /* 2301 * The segment actually starts after the window. 2302 * th->th_seq + tlen - tp->rcv_nxt - tp->rcv_wnd >= tlen 2303 * th->th_seq - tp->rcv_nxt - tp->rcv_wnd >= 0 2304 * th->th_seq >= tp->rcv_nxt + tp->rcv_wnd 2305 */ 2306 TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, tlen); 2307 2308 /* 2309 * If a new connection request is received while in 2310 * TIME_WAIT, drop the old connection and start over 2311 * if the sequence numbers are above the previous 2312 * ones. 2313 * 2314 * NOTE: We need to put the header fields back into 2315 * network order. 2316 */ 2317 if ((tiflags & TH_SYN) && 2318 tp->t_state == TCPS_TIME_WAIT && 2319 SEQ_GT(th->th_seq, tp->rcv_nxt)) { 2320 tp = tcp_close(tp); 2321 tcp_fields_to_net(th); 2322 m_freem(tcp_saveti); 2323 tcp_saveti = NULL; 2324 goto findpcb; 2325 } 2326 2327 /* 2328 * If window is closed can only take segments at 2329 * window edge, and have to drop data and PUSH from 2330 * incoming segments. Continue processing, but 2331 * remember to ack. Otherwise, drop segment 2332 * and (if not RST) ack. 2333 */ 2334 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 2335 KASSERT(todrop == tlen); 2336 tp->t_flags |= TF_ACKNOW; 2337 TCP_STATINC(TCP_STAT_RCVWINPROBE); 2338 } else { 2339 goto dropafterack; 2340 } 2341 } else { 2342 TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, todrop); 2343 } 2344 m_adj(m, -todrop); 2345 tlen -= todrop; 2346 tiflags &= ~(TH_PUSH|TH_FIN); 2347 } 2348 2349 /* 2350 * If last ACK falls within this segment's sequence numbers, 2351 * record the timestamp. 2352 * NOTE: 2353 * 1) That the test incorporates suggestions from the latest 2354 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 2355 * 2) That updating only on newer timestamps interferes with 2356 * our earlier PAWS tests, so this check should be solely 2357 * predicated on the sequence space of this segment. 2358 * 3) That we modify the segment boundary check to be 2359 * Last.ACK.Sent <= SEG.SEQ + SEG.Len 2360 * instead of RFC1323's 2361 * Last.ACK.Sent < SEG.SEQ + SEG.Len, 2362 * This modified check allows us to overcome RFC1323's 2363 * limitations as described in Stevens TCP/IP Illustrated 2364 * Vol. 2 p.869. In such cases, we can still calculate the 2365 * RTT correctly when RCV.NXT == Last.ACK.Sent. 2366 */ 2367 if (opti.ts_present && 2368 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 2369 SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen + 2370 ((tiflags & (TH_SYN|TH_FIN)) != 0))) { 2371 tp->ts_recent_age = tcp_now; 2372 tp->ts_recent = opti.ts_val; 2373 } 2374 2375 /* 2376 * If the RST bit is set examine the state: 2377 * RECEIVED state: 2378 * If passive open, return to LISTEN state. 2379 * If active open, inform user that connection was refused. 2380 * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT states: 2381 * Inform user that connection was reset, and close tcb. 2382 * CLOSING, LAST_ACK, TIME_WAIT states: 2383 * Close the tcb. 2384 */ 2385 if (tiflags & TH_RST) { 2386 if (th->th_seq != tp->rcv_nxt) 2387 goto dropafterack_ratelim; 2388 2389 switch (tp->t_state) { 2390 case TCPS_SYN_RECEIVED: 2391 so->so_error = ECONNREFUSED; 2392 goto close; 2393 2394 case TCPS_ESTABLISHED: 2395 case TCPS_FIN_WAIT_1: 2396 case TCPS_FIN_WAIT_2: 2397 case TCPS_CLOSE_WAIT: 2398 so->so_error = ECONNRESET; 2399 close: 2400 tp->t_state = TCPS_CLOSED; 2401 TCP_STATINC(TCP_STAT_DROPS); 2402 tp = tcp_close(tp); 2403 goto drop; 2404 2405 case TCPS_CLOSING: 2406 case TCPS_LAST_ACK: 2407 case TCPS_TIME_WAIT: 2408 tp = tcp_close(tp); 2409 goto drop; 2410 } 2411 } 2412 2413 /* 2414 * Since we've covered the SYN-SENT and SYN-RECEIVED states above 2415 * we must be in a synchronized state. RFC791 states (under RST 2416 * generation) that any unacceptable segment (an out-of-order SYN 2417 * qualifies) received in a synchronized state must elicit only an 2418 * empty acknowledgment segment ... and the connection remains in 2419 * the same state. 2420 */ 2421 if (tiflags & TH_SYN) { 2422 if (tp->rcv_nxt == th->th_seq) { 2423 tcp_respond(tp, m, m, th, (tcp_seq)0, th->th_ack - 1, 2424 TH_ACK); 2425 if (tcp_saveti) 2426 m_freem(tcp_saveti); 2427 return; 2428 } 2429 2430 goto dropafterack_ratelim; 2431 } 2432 2433 /* 2434 * If the ACK bit is off we drop the segment and return. 2435 */ 2436 if ((tiflags & TH_ACK) == 0) { 2437 if (tp->t_flags & TF_ACKNOW) 2438 goto dropafterack; 2439 goto drop; 2440 } 2441 2442 /* 2443 * From here on, we're doing ACK processing. 2444 */ 2445 2446 switch (tp->t_state) { 2447 /* 2448 * In SYN_RECEIVED state if the ack ACKs our SYN then enter 2449 * ESTABLISHED state and continue processing, otherwise 2450 * send an RST. 2451 */ 2452 case TCPS_SYN_RECEIVED: 2453 if (SEQ_GT(tp->snd_una, th->th_ack) || 2454 SEQ_GT(th->th_ack, tp->snd_max)) 2455 goto dropwithreset; 2456 TCP_STATINC(TCP_STAT_CONNECTS); 2457 soisconnected(so); 2458 tcp_established(tp); 2459 /* Do window scaling? */ 2460 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2461 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2462 tp->snd_scale = tp->requested_s_scale; 2463 tp->rcv_scale = tp->request_r_scale; 2464 } 2465 TCP_REASS_LOCK(tp); 2466 (void)tcp_reass(tp, NULL, NULL, tlen); 2467 tp->snd_wl1 = th->th_seq - 1; 2468 /* FALLTHROUGH */ 2469 2470 /* 2471 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 2472 * ACKs. If the ack is in the range 2473 * tp->snd_una < th->th_ack <= tp->snd_max 2474 * then advance tp->snd_una to th->th_ack and drop 2475 * data from the retransmission queue. If this ACK reflects 2476 * more up to date window information we update our window information. 2477 */ 2478 case TCPS_ESTABLISHED: 2479 case TCPS_FIN_WAIT_1: 2480 case TCPS_FIN_WAIT_2: 2481 case TCPS_CLOSE_WAIT: 2482 case TCPS_CLOSING: 2483 case TCPS_LAST_ACK: 2484 case TCPS_TIME_WAIT: 2485 if (SEQ_LEQ(th->th_ack, tp->snd_una)) { 2486 if (tlen == 0 && !dupseg && tiwin == tp->snd_wnd) { 2487 TCP_STATINC(TCP_STAT_RCVDUPACK); 2488 /* 2489 * If we have outstanding data (other than 2490 * a window probe), this is a completely 2491 * duplicate ack (ie, window info didn't 2492 * change), the ack is the biggest we've 2493 * seen and we've seen exactly our rexmt 2494 * threshhold of them, assume a packet 2495 * has been dropped and retransmit it. 2496 * Kludge snd_nxt & the congestion 2497 * window so we send only this one 2498 * packet. 2499 */ 2500 if (TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 || 2501 th->th_ack != tp->snd_una) 2502 tp->t_dupacks = 0; 2503 else if (tp->t_partialacks < 0 && 2504 (++tp->t_dupacks == tcprexmtthresh || 2505 TCP_FACK_FASTRECOV(tp))) { 2506 /* 2507 * Do the fast retransmit, and adjust 2508 * congestion control paramenters. 2509 */ 2510 if (tp->t_congctl->fast_retransmit(tp, th)) { 2511 /* False fast retransmit */ 2512 break; 2513 } 2514 goto drop; 2515 } else if (tp->t_dupacks > tcprexmtthresh) { 2516 tp->snd_cwnd += tp->t_segsz; 2517 KERNEL_LOCK(1, NULL); 2518 (void)tcp_output(tp); 2519 KERNEL_UNLOCK_ONE(NULL); 2520 goto drop; 2521 } 2522 } else { 2523 /* 2524 * If the ack appears to be very old, only 2525 * allow data that is in-sequence. This 2526 * makes it somewhat more difficult to insert 2527 * forged data by guessing sequence numbers. 2528 * Sent an ack to try to update the send 2529 * sequence number on the other side. 2530 */ 2531 if (tlen && th->th_seq != tp->rcv_nxt && 2532 SEQ_LT(th->th_ack, 2533 tp->snd_una - tp->max_sndwnd)) 2534 goto dropafterack; 2535 } 2536 break; 2537 } 2538 /* 2539 * If the congestion window was inflated to account 2540 * for the other side's cached packets, retract it. 2541 */ 2542 tp->t_congctl->fast_retransmit_newack(tp, th); 2543 2544 if (SEQ_GT(th->th_ack, tp->snd_max)) { 2545 TCP_STATINC(TCP_STAT_RCVACKTOOMUCH); 2546 goto dropafterack; 2547 } 2548 acked = th->th_ack - tp->snd_una; 2549 tcps = TCP_STAT_GETREF(); 2550 tcps[TCP_STAT_RCVACKPACK]++; 2551 tcps[TCP_STAT_RCVACKBYTE] += acked; 2552 TCP_STAT_PUTREF(); 2553 2554 /* 2555 * If we have a timestamp reply, update smoothed 2556 * round trip time. If no timestamp is present but 2557 * transmit timer is running and timed sequence 2558 * number was acked, update smoothed round trip time. 2559 * Since we now have an rtt measurement, cancel the 2560 * timer backoff (cf., Phil Karn's retransmit alg.). 2561 * Recompute the initial retransmit timer. 2562 */ 2563 if (ts_rtt) 2564 tcp_xmit_timer(tp, ts_rtt - 1); 2565 else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) 2566 tcp_xmit_timer(tp, tcp_now - tp->t_rtttime); 2567 2568 /* 2569 * If all outstanding data is acked, stop retransmit 2570 * timer and remember to restart (more output or persist). 2571 * If there is more data to be acked, restart retransmit 2572 * timer, using current (possibly backed-off) value. 2573 */ 2574 if (th->th_ack == tp->snd_max) { 2575 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2576 needoutput = 1; 2577 } else if (TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) 2578 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 2579 2580 /* 2581 * New data has been acked, adjust the congestion window. 2582 */ 2583 tp->t_congctl->newack(tp, th); 2584 2585 nd6_hint(tp); 2586 if (acked > so->so_snd.sb_cc) { 2587 tp->snd_wnd -= so->so_snd.sb_cc; 2588 sbdrop(&so->so_snd, (int)so->so_snd.sb_cc); 2589 ourfinisacked = 1; 2590 } else { 2591 if (acked > (tp->t_lastoff - tp->t_inoff)) 2592 tp->t_lastm = NULL; 2593 sbdrop(&so->so_snd, acked); 2594 tp->t_lastoff -= acked; 2595 if (tp->snd_wnd > acked) 2596 tp->snd_wnd -= acked; 2597 else 2598 tp->snd_wnd = 0; 2599 ourfinisacked = 0; 2600 } 2601 sowwakeup(so); 2602 2603 icmp_check(tp, th, acked); 2604 2605 tp->snd_una = th->th_ack; 2606 if (SEQ_GT(tp->snd_una, tp->snd_fack)) 2607 tp->snd_fack = tp->snd_una; 2608 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2609 tp->snd_nxt = tp->snd_una; 2610 if (SEQ_LT(tp->snd_high, tp->snd_una)) 2611 tp->snd_high = tp->snd_una; 2612 2613 switch (tp->t_state) { 2614 2615 /* 2616 * In FIN_WAIT_1 STATE in addition to the processing 2617 * for the ESTABLISHED state if our FIN is now acknowledged 2618 * then enter FIN_WAIT_2. 2619 */ 2620 case TCPS_FIN_WAIT_1: 2621 if (ourfinisacked) { 2622 /* 2623 * If we can't receive any more 2624 * data, then closing user can proceed. 2625 * Starting the timer is contrary to the 2626 * specification, but if we don't get a FIN 2627 * we'll hang forever. 2628 */ 2629 if (so->so_state & SS_CANTRCVMORE) { 2630 soisdisconnected(so); 2631 if (tp->t_maxidle > 0) 2632 TCP_TIMER_ARM(tp, TCPT_2MSL, 2633 tp->t_maxidle); 2634 } 2635 tp->t_state = TCPS_FIN_WAIT_2; 2636 } 2637 break; 2638 2639 /* 2640 * In CLOSING STATE in addition to the processing for 2641 * the ESTABLISHED state if the ACK acknowledges our FIN 2642 * then enter the TIME-WAIT state, otherwise ignore 2643 * the segment. 2644 */ 2645 case TCPS_CLOSING: 2646 if (ourfinisacked) { 2647 tp->t_state = TCPS_TIME_WAIT; 2648 tcp_canceltimers(tp); 2649 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * tp->t_msl); 2650 soisdisconnected(so); 2651 } 2652 break; 2653 2654 /* 2655 * In LAST_ACK, we may still be waiting for data to drain 2656 * and/or to be acked, as well as for the ack of our FIN. 2657 * If our FIN is now acknowledged, delete the TCB, 2658 * enter the closed state and return. 2659 */ 2660 case TCPS_LAST_ACK: 2661 if (ourfinisacked) { 2662 tp = tcp_close(tp); 2663 goto drop; 2664 } 2665 break; 2666 2667 /* 2668 * In TIME_WAIT state the only thing that should arrive 2669 * is a retransmission of the remote FIN. Acknowledge 2670 * it and restart the finack timer. 2671 */ 2672 case TCPS_TIME_WAIT: 2673 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * tp->t_msl); 2674 goto dropafterack; 2675 } 2676 } 2677 2678 step6: 2679 /* 2680 * Update window information. 2681 * Don't look at window if no ACK: TAC's send garbage on first SYN. 2682 */ 2683 if ((tiflags & TH_ACK) && (SEQ_LT(tp->snd_wl1, th->th_seq) || 2684 (tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) || 2685 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) { 2686 /* keep track of pure window updates */ 2687 if (tlen == 0 && 2688 tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) 2689 TCP_STATINC(TCP_STAT_RCVWINUPD); 2690 tp->snd_wnd = tiwin; 2691 tp->snd_wl1 = th->th_seq; 2692 tp->snd_wl2 = th->th_ack; 2693 if (tp->snd_wnd > tp->max_sndwnd) 2694 tp->max_sndwnd = tp->snd_wnd; 2695 needoutput = 1; 2696 } 2697 2698 /* 2699 * Process segments with URG. 2700 */ 2701 if ((tiflags & TH_URG) && th->th_urp && 2702 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2703 /* 2704 * This is a kludge, but if we receive and accept 2705 * random urgent pointers, we'll crash in 2706 * soreceive. It's hard to imagine someone 2707 * actually wanting to send this much urgent data. 2708 */ 2709 if (th->th_urp + so->so_rcv.sb_cc > sb_max) { 2710 th->th_urp = 0; /* XXX */ 2711 tiflags &= ~TH_URG; /* XXX */ 2712 goto dodata; /* XXX */ 2713 } 2714 2715 /* 2716 * If this segment advances the known urgent pointer, 2717 * then mark the data stream. This should not happen 2718 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 2719 * a FIN has been received from the remote side. 2720 * In these states we ignore the URG. 2721 * 2722 * According to RFC961 (Assigned Protocols), 2723 * the urgent pointer points to the last octet 2724 * of urgent data. We continue, however, 2725 * to consider it to indicate the first octet 2726 * of data past the urgent section as the original 2727 * spec states (in one of two places). 2728 */ 2729 if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) { 2730 tp->rcv_up = th->th_seq + th->th_urp; 2731 so->so_oobmark = so->so_rcv.sb_cc + 2732 (tp->rcv_up - tp->rcv_nxt) - 1; 2733 if (so->so_oobmark == 0) 2734 so->so_state |= SS_RCVATMARK; 2735 sohasoutofband(so); 2736 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); 2737 } 2738 2739 /* 2740 * Remove out of band data so doesn't get presented to user. 2741 * This can happen independent of advancing the URG pointer, 2742 * but if two URG's are pending at once, some out-of-band 2743 * data may creep in... ick. 2744 */ 2745 if (th->th_urp <= (u_int16_t)tlen && 2746 (so->so_options & SO_OOBINLINE) == 0) 2747 tcp_pulloutofband(so, th, m, hdroptlen); 2748 } else { 2749 /* 2750 * If no out of band data is expected, 2751 * pull receive urgent pointer along 2752 * with the receive window. 2753 */ 2754 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) 2755 tp->rcv_up = tp->rcv_nxt; 2756 } 2757 dodata: 2758 2759 /* 2760 * Process the segment text, merging it into the TCP sequencing queue, 2761 * and arranging for acknowledgement of receipt if necessary. 2762 * This process logically involves adjusting tp->rcv_wnd as data 2763 * is presented to the user (this happens in tcp_usrreq.c, 2764 * tcp_rcvd()). If a FIN has already been received on this 2765 * connection then we just ignore the text. 2766 */ 2767 if ((tlen || (tiflags & TH_FIN)) && 2768 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2769 /* 2770 * Handle the common case: 2771 * o Segment is the next to be received, and 2772 * o The queue is empty, and 2773 * o The connection is established 2774 * In this case, we avoid calling tcp_reass. 2775 * 2776 * tcp_setup_ack: set DELACK for segments received in order, 2777 * but ack immediately when segments are out of order (so that 2778 * fast retransmit can work). 2779 */ 2780 TCP_REASS_LOCK(tp); 2781 if (th->th_seq == tp->rcv_nxt && 2782 TAILQ_FIRST(&tp->segq) == NULL && 2783 tp->t_state == TCPS_ESTABLISHED) { 2784 tcp_setup_ack(tp, th); 2785 tp->rcv_nxt += tlen; 2786 tiflags = th->th_flags & TH_FIN; 2787 tcps = TCP_STAT_GETREF(); 2788 tcps[TCP_STAT_RCVPACK]++; 2789 tcps[TCP_STAT_RCVBYTE] += tlen; 2790 TCP_STAT_PUTREF(); 2791 nd6_hint(tp); 2792 if (so->so_state & SS_CANTRCVMORE) { 2793 m_freem(m); 2794 } else { 2795 m_adj(m, hdroptlen); 2796 sbappendstream(&(so)->so_rcv, m); 2797 } 2798 TCP_REASS_UNLOCK(tp); 2799 sorwakeup(so); 2800 } else { 2801 m_adj(m, hdroptlen); 2802 tiflags = tcp_reass(tp, th, m, tlen); 2803 tp->t_flags |= TF_ACKNOW; 2804 } 2805 2806 /* 2807 * Note the amount of data that peer has sent into 2808 * our window, in order to estimate the sender's 2809 * buffer size. 2810 */ 2811 len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); 2812 } else { 2813 m_freem(m); 2814 m = NULL; 2815 tiflags &= ~TH_FIN; 2816 } 2817 2818 /* 2819 * If FIN is received ACK the FIN and let the user know 2820 * that the connection is closing. Ignore a FIN received before 2821 * the connection is fully established. 2822 */ 2823 if ((tiflags & TH_FIN) && TCPS_HAVEESTABLISHED(tp->t_state)) { 2824 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2825 socantrcvmore(so); 2826 tp->t_flags |= TF_ACKNOW; 2827 tp->rcv_nxt++; 2828 } 2829 switch (tp->t_state) { 2830 2831 /* 2832 * In ESTABLISHED STATE enter the CLOSE_WAIT state. 2833 */ 2834 case TCPS_ESTABLISHED: 2835 tp->t_state = TCPS_CLOSE_WAIT; 2836 break; 2837 2838 /* 2839 * If still in FIN_WAIT_1 STATE FIN has not been acked so 2840 * enter the CLOSING state. 2841 */ 2842 case TCPS_FIN_WAIT_1: 2843 tp->t_state = TCPS_CLOSING; 2844 break; 2845 2846 /* 2847 * In FIN_WAIT_2 state enter the TIME_WAIT state, 2848 * starting the time-wait timer, turning off the other 2849 * standard timers. 2850 */ 2851 case TCPS_FIN_WAIT_2: 2852 tp->t_state = TCPS_TIME_WAIT; 2853 tcp_canceltimers(tp); 2854 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * tp->t_msl); 2855 soisdisconnected(so); 2856 break; 2857 2858 /* 2859 * In TIME_WAIT state restart the 2 MSL time_wait timer. 2860 */ 2861 case TCPS_TIME_WAIT: 2862 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * tp->t_msl); 2863 break; 2864 } 2865 } 2866 #ifdef TCP_DEBUG 2867 if (so->so_options & SO_DEBUG) 2868 tcp_trace(TA_INPUT, ostate, tp, tcp_saveti, 0); 2869 #endif 2870 2871 /* 2872 * Return any desired output. 2873 */ 2874 if (needoutput || (tp->t_flags & TF_ACKNOW)) { 2875 KERNEL_LOCK(1, NULL); 2876 (void)tcp_output(tp); 2877 KERNEL_UNLOCK_ONE(NULL); 2878 } 2879 if (tcp_saveti) 2880 m_freem(tcp_saveti); 2881 2882 if (tp->t_state == TCPS_TIME_WAIT 2883 && (so->so_state & SS_NOFDREF) 2884 && (tp->t_inpcb || af != AF_INET) 2885 && (tp->t_in6pcb || af != AF_INET6) 2886 && ((af == AF_INET ? tcp4_vtw_enable : tcp6_vtw_enable) & 1) != 0 2887 && TAILQ_EMPTY(&tp->segq) 2888 && vtw_add(af, tp)) { 2889 ; 2890 } 2891 return; 2892 2893 badsyn: 2894 /* 2895 * Received a bad SYN. Increment counters and dropwithreset. 2896 */ 2897 TCP_STATINC(TCP_STAT_BADSYN); 2898 tp = NULL; 2899 goto dropwithreset; 2900 2901 dropafterack: 2902 /* 2903 * Generate an ACK dropping incoming segment if it occupies 2904 * sequence space, where the ACK reflects our state. 2905 */ 2906 if (tiflags & TH_RST) 2907 goto drop; 2908 goto dropafterack2; 2909 2910 dropafterack_ratelim: 2911 /* 2912 * We may want to rate-limit ACKs against SYN/RST attack. 2913 */ 2914 if (ppsratecheck(&tcp_ackdrop_ppslim_last, &tcp_ackdrop_ppslim_count, 2915 tcp_ackdrop_ppslim) == 0) { 2916 /* XXX stat */ 2917 goto drop; 2918 } 2919 2920 dropafterack2: 2921 m_freem(m); 2922 tp->t_flags |= TF_ACKNOW; 2923 KERNEL_LOCK(1, NULL); 2924 (void)tcp_output(tp); 2925 KERNEL_UNLOCK_ONE(NULL); 2926 if (tcp_saveti) 2927 m_freem(tcp_saveti); 2928 return; 2929 2930 dropwithreset_ratelim: 2931 /* 2932 * We may want to rate-limit RSTs in certain situations, 2933 * particularly if we are sending an RST in response to 2934 * an attempt to connect to or otherwise communicate with 2935 * a port for which we have no socket. 2936 */ 2937 if (ppsratecheck(&tcp_rst_ppslim_last, &tcp_rst_ppslim_count, 2938 tcp_rst_ppslim) == 0) { 2939 /* XXX stat */ 2940 goto drop; 2941 } 2942 2943 dropwithreset: 2944 /* 2945 * Generate a RST, dropping incoming segment. 2946 * Make ACK acceptable to originator of segment. 2947 */ 2948 if (tiflags & TH_RST) 2949 goto drop; 2950 if (tiflags & TH_ACK) { 2951 (void)tcp_respond(tp, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 2952 } else { 2953 if (tiflags & TH_SYN) 2954 tlen++; 2955 (void)tcp_respond(tp, m, m, th, th->th_seq + tlen, (tcp_seq)0, 2956 TH_RST|TH_ACK); 2957 } 2958 if (tcp_saveti) 2959 m_freem(tcp_saveti); 2960 return; 2961 2962 badcsum: 2963 drop: 2964 /* 2965 * Drop space held by incoming segment and return. 2966 */ 2967 if (tp) { 2968 if (tp->t_inpcb) 2969 so = tp->t_inpcb->inp_socket; 2970 #ifdef INET6 2971 else if (tp->t_in6pcb) 2972 so = tp->t_in6pcb->in6p_socket; 2973 #endif 2974 else 2975 so = NULL; 2976 #ifdef TCP_DEBUG 2977 if (so && (so->so_options & SO_DEBUG) != 0) 2978 tcp_trace(TA_DROP, ostate, tp, tcp_saveti, 0); 2979 #endif 2980 } 2981 if (tcp_saveti) 2982 m_freem(tcp_saveti); 2983 m_freem(m); 2984 return; 2985 } 2986 2987 #ifdef TCP_SIGNATURE 2988 int 2989 tcp_signature_apply(void *fstate, void *data, u_int len) 2990 { 2991 2992 MD5Update(fstate, (u_char *)data, len); 2993 return (0); 2994 } 2995 2996 struct secasvar * 2997 tcp_signature_getsav(struct mbuf *m) 2998 { 2999 struct ip *ip; 3000 struct ip6_hdr *ip6; 3001 3002 ip = mtod(m, struct ip *); 3003 switch (ip->ip_v) { 3004 case 4: 3005 ip = mtod(m, struct ip *); 3006 ip6 = NULL; 3007 break; 3008 case 6: 3009 ip = NULL; 3010 ip6 = mtod(m, struct ip6_hdr *); 3011 break; 3012 default: 3013 return (NULL); 3014 } 3015 3016 #ifdef IPSEC 3017 union sockaddr_union dst; 3018 3019 /* Extract the destination from the IP header in the mbuf. */ 3020 memset(&dst, 0, sizeof(union sockaddr_union)); 3021 if (ip != NULL) { 3022 dst.sa.sa_len = sizeof(struct sockaddr_in); 3023 dst.sa.sa_family = AF_INET; 3024 dst.sin.sin_addr = ip->ip_dst; 3025 } else { 3026 dst.sa.sa_len = sizeof(struct sockaddr_in6); 3027 dst.sa.sa_family = AF_INET6; 3028 dst.sin6.sin6_addr = ip6->ip6_dst; 3029 } 3030 3031 /* 3032 * Look up an SADB entry which matches the address of the peer. 3033 */ 3034 return KEY_LOOKUP_SA(&dst, IPPROTO_TCP, htonl(TCP_SIG_SPI), 0, 0); 3035 #else 3036 return NULL; 3037 #endif 3038 } 3039 3040 int 3041 tcp_signature(struct mbuf *m, struct tcphdr *th, int thoff, 3042 struct secasvar *sav, char *sig) 3043 { 3044 MD5_CTX ctx; 3045 struct ip *ip; 3046 struct ipovly *ipovly; 3047 #ifdef INET6 3048 struct ip6_hdr *ip6; 3049 struct ip6_hdr_pseudo ip6pseudo; 3050 #endif 3051 struct ippseudo ippseudo; 3052 struct tcphdr th0; 3053 int l, tcphdrlen; 3054 3055 if (sav == NULL) 3056 return (-1); 3057 3058 tcphdrlen = th->th_off * 4; 3059 3060 switch (mtod(m, struct ip *)->ip_v) { 3061 case 4: 3062 MD5Init(&ctx); 3063 ip = mtod(m, struct ip *); 3064 memset(&ippseudo, 0, sizeof(ippseudo)); 3065 ipovly = (struct ipovly *)ip; 3066 ippseudo.ippseudo_src = ipovly->ih_src; 3067 ippseudo.ippseudo_dst = ipovly->ih_dst; 3068 ippseudo.ippseudo_pad = 0; 3069 ippseudo.ippseudo_p = IPPROTO_TCP; 3070 ippseudo.ippseudo_len = htons(m->m_pkthdr.len - thoff); 3071 MD5Update(&ctx, (char *)&ippseudo, sizeof(ippseudo)); 3072 break; 3073 #if INET6 3074 case 6: 3075 MD5Init(&ctx); 3076 ip6 = mtod(m, struct ip6_hdr *); 3077 memset(&ip6pseudo, 0, sizeof(ip6pseudo)); 3078 ip6pseudo.ip6ph_src = ip6->ip6_src; 3079 in6_clearscope(&ip6pseudo.ip6ph_src); 3080 ip6pseudo.ip6ph_dst = ip6->ip6_dst; 3081 in6_clearscope(&ip6pseudo.ip6ph_dst); 3082 ip6pseudo.ip6ph_len = htons(m->m_pkthdr.len - thoff); 3083 ip6pseudo.ip6ph_nxt = IPPROTO_TCP; 3084 MD5Update(&ctx, (char *)&ip6pseudo, sizeof(ip6pseudo)); 3085 break; 3086 #endif 3087 default: 3088 return (-1); 3089 } 3090 3091 th0 = *th; 3092 th0.th_sum = 0; 3093 MD5Update(&ctx, (char *)&th0, sizeof(th0)); 3094 3095 l = m->m_pkthdr.len - thoff - tcphdrlen; 3096 if (l > 0) 3097 m_apply(m, thoff + tcphdrlen, 3098 m->m_pkthdr.len - thoff - tcphdrlen, 3099 tcp_signature_apply, &ctx); 3100 3101 MD5Update(&ctx, _KEYBUF(sav->key_auth), _KEYLEN(sav->key_auth)); 3102 MD5Final(sig, &ctx); 3103 3104 return (0); 3105 } 3106 #endif 3107 3108 /* 3109 * Parse and process tcp options. 3110 * 3111 * Returns -1 if this segment should be dropped. (eg. wrong signature) 3112 * Otherwise returns 0. 3113 */ 3114 static int 3115 tcp_dooptions(struct tcpcb *tp, const u_char *cp, int cnt, struct tcphdr *th, 3116 struct mbuf *m, int toff, struct tcp_opt_info *oi) 3117 { 3118 u_int16_t mss; 3119 int opt, optlen = 0; 3120 #ifdef TCP_SIGNATURE 3121 void *sigp = NULL; 3122 char sigbuf[TCP_SIGLEN]; 3123 struct secasvar *sav = NULL; 3124 #endif 3125 3126 for (; cp && cnt > 0; cnt -= optlen, cp += optlen) { 3127 opt = cp[0]; 3128 if (opt == TCPOPT_EOL) 3129 break; 3130 if (opt == TCPOPT_NOP) 3131 optlen = 1; 3132 else { 3133 if (cnt < 2) 3134 break; 3135 optlen = cp[1]; 3136 if (optlen < 2 || optlen > cnt) 3137 break; 3138 } 3139 switch (opt) { 3140 3141 default: 3142 continue; 3143 3144 case TCPOPT_MAXSEG: 3145 if (optlen != TCPOLEN_MAXSEG) 3146 continue; 3147 if (!(th->th_flags & TH_SYN)) 3148 continue; 3149 if (TCPS_HAVERCVDSYN(tp->t_state)) 3150 continue; 3151 memcpy(&mss, cp + 2, sizeof(mss)); 3152 oi->maxseg = ntohs(mss); 3153 break; 3154 3155 case TCPOPT_WINDOW: 3156 if (optlen != TCPOLEN_WINDOW) 3157 continue; 3158 if (!(th->th_flags & TH_SYN)) 3159 continue; 3160 if (TCPS_HAVERCVDSYN(tp->t_state)) 3161 continue; 3162 tp->t_flags |= TF_RCVD_SCALE; 3163 tp->requested_s_scale = cp[2]; 3164 if (tp->requested_s_scale > TCP_MAX_WINSHIFT) { 3165 char buf[INET6_ADDRSTRLEN]; 3166 struct ip *ip = mtod(m, struct ip *); 3167 #ifdef INET6 3168 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *); 3169 #endif 3170 3171 switch (ip->ip_v) { 3172 case 4: 3173 in_print(buf, sizeof(buf), 3174 &ip->ip_src); 3175 break; 3176 #ifdef INET6 3177 case 6: 3178 in6_print(buf, sizeof(buf), 3179 &ip6->ip6_src); 3180 break; 3181 #endif 3182 default: 3183 strlcpy(buf, "(unknown)", sizeof(buf)); 3184 break; 3185 } 3186 3187 log(LOG_ERR, "TCP: invalid wscale %d from %s, " 3188 "assuming %d\n", 3189 tp->requested_s_scale, buf, 3190 TCP_MAX_WINSHIFT); 3191 tp->requested_s_scale = TCP_MAX_WINSHIFT; 3192 } 3193 break; 3194 3195 case TCPOPT_TIMESTAMP: 3196 if (optlen != TCPOLEN_TIMESTAMP) 3197 continue; 3198 oi->ts_present = 1; 3199 memcpy(&oi->ts_val, cp + 2, sizeof(oi->ts_val)); 3200 NTOHL(oi->ts_val); 3201 memcpy(&oi->ts_ecr, cp + 6, sizeof(oi->ts_ecr)); 3202 NTOHL(oi->ts_ecr); 3203 3204 if (!(th->th_flags & TH_SYN)) 3205 continue; 3206 if (TCPS_HAVERCVDSYN(tp->t_state)) 3207 continue; 3208 /* 3209 * A timestamp received in a SYN makes 3210 * it ok to send timestamp requests and replies. 3211 */ 3212 tp->t_flags |= TF_RCVD_TSTMP; 3213 tp->ts_recent = oi->ts_val; 3214 tp->ts_recent_age = tcp_now; 3215 break; 3216 3217 case TCPOPT_SACK_PERMITTED: 3218 if (optlen != TCPOLEN_SACK_PERMITTED) 3219 continue; 3220 if (!(th->th_flags & TH_SYN)) 3221 continue; 3222 if (TCPS_HAVERCVDSYN(tp->t_state)) 3223 continue; 3224 if (tcp_do_sack) { 3225 tp->t_flags |= TF_SACK_PERMIT; 3226 tp->t_flags |= TF_WILL_SACK; 3227 } 3228 break; 3229 3230 case TCPOPT_SACK: 3231 tcp_sack_option(tp, th, cp, optlen); 3232 break; 3233 #ifdef TCP_SIGNATURE 3234 case TCPOPT_SIGNATURE: 3235 if (optlen != TCPOLEN_SIGNATURE) 3236 continue; 3237 if (sigp && 3238 !consttime_memequal(sigp, cp + 2, TCP_SIGLEN)) 3239 return (-1); 3240 3241 sigp = sigbuf; 3242 memcpy(sigbuf, cp + 2, TCP_SIGLEN); 3243 tp->t_flags |= TF_SIGNATURE; 3244 break; 3245 #endif 3246 } 3247 } 3248 3249 #ifndef TCP_SIGNATURE 3250 return 0; 3251 #else 3252 if (tp->t_flags & TF_SIGNATURE) { 3253 sav = tcp_signature_getsav(m); 3254 if (sav == NULL && tp->t_state == TCPS_LISTEN) 3255 return (-1); 3256 } 3257 3258 if ((sigp ? TF_SIGNATURE : 0) ^ (tp->t_flags & TF_SIGNATURE)) 3259 goto out; 3260 3261 if (sigp) { 3262 char sig[TCP_SIGLEN]; 3263 3264 tcp_fields_to_net(th); 3265 if (tcp_signature(m, th, toff, sav, sig) < 0) { 3266 tcp_fields_to_host(th); 3267 goto out; 3268 } 3269 tcp_fields_to_host(th); 3270 3271 if (!consttime_memequal(sig, sigp, TCP_SIGLEN)) { 3272 TCP_STATINC(TCP_STAT_BADSIG); 3273 goto out; 3274 } else 3275 TCP_STATINC(TCP_STAT_GOODSIG); 3276 3277 key_sa_recordxfer(sav, m); 3278 KEY_SA_UNREF(&sav); 3279 } 3280 return 0; 3281 out: 3282 if (sav != NULL) 3283 KEY_SA_UNREF(&sav); 3284 return -1; 3285 #endif 3286 } 3287 3288 /* 3289 * Pull out of band byte out of a segment so 3290 * it doesn't appear in the user's data queue. 3291 * It is still reflected in the segment length for 3292 * sequencing purposes. 3293 */ 3294 void 3295 tcp_pulloutofband(struct socket *so, struct tcphdr *th, 3296 struct mbuf *m, int off) 3297 { 3298 int cnt = off + th->th_urp - 1; 3299 3300 while (cnt >= 0) { 3301 if (m->m_len > cnt) { 3302 char *cp = mtod(m, char *) + cnt; 3303 struct tcpcb *tp = sototcpcb(so); 3304 3305 tp->t_iobc = *cp; 3306 tp->t_oobflags |= TCPOOB_HAVEDATA; 3307 memmove(cp, cp + 1, (unsigned)(m->m_len - cnt - 1)); 3308 m->m_len--; 3309 return; 3310 } 3311 cnt -= m->m_len; 3312 m = m->m_next; 3313 if (m == NULL) 3314 break; 3315 } 3316 panic("tcp_pulloutofband"); 3317 } 3318 3319 /* 3320 * Collect new round-trip time estimate 3321 * and update averages and current timeout. 3322 * 3323 * rtt is in units of slow ticks (typically 500 ms) -- essentially the 3324 * difference of two timestamps. 3325 */ 3326 void 3327 tcp_xmit_timer(struct tcpcb *tp, uint32_t rtt) 3328 { 3329 int32_t delta; 3330 3331 TCP_STATINC(TCP_STAT_RTTUPDATED); 3332 if (tp->t_srtt != 0) { 3333 /* 3334 * Compute the amount to add to srtt for smoothing, 3335 * *alpha, or 2^(-TCP_RTT_SHIFT). Because 3336 * srtt is stored in 1/32 slow ticks, we conceptually 3337 * shift left 5 bits, subtract srtt to get the 3338 * diference, and then shift right by TCP_RTT_SHIFT 3339 * (3) to obtain 1/8 of the difference. 3340 */ 3341 delta = (rtt << 2) - (tp->t_srtt >> TCP_RTT_SHIFT); 3342 /* 3343 * This can never happen, because delta's lowest 3344 * possible value is 1/8 of t_srtt. But if it does, 3345 * set srtt to some reasonable value, here chosen 3346 * as 1/8 tick. 3347 */ 3348 if ((tp->t_srtt += delta) <= 0) 3349 tp->t_srtt = 1 << 2; 3350 /* 3351 * RFC2988 requires that rttvar be updated first. 3352 * This code is compliant because "delta" is the old 3353 * srtt minus the new observation (scaled). 3354 * 3355 * RFC2988 says: 3356 * rttvar = (1-beta) * rttvar + beta * |srtt-observed| 3357 * 3358 * delta is in units of 1/32 ticks, and has then been 3359 * divided by 8. This is equivalent to being in 1/16s 3360 * units and divided by 4. Subtract from it 1/4 of 3361 * the existing rttvar to form the (signed) amount to 3362 * adjust. 3363 */ 3364 if (delta < 0) 3365 delta = -delta; 3366 delta -= (tp->t_rttvar >> TCP_RTTVAR_SHIFT); 3367 /* 3368 * As with srtt, this should never happen. There is 3369 * no support in RFC2988 for this operation. But 1/4s 3370 * as rttvar when faced with something arguably wrong 3371 * is ok. 3372 */ 3373 if ((tp->t_rttvar += delta) <= 0) 3374 tp->t_rttvar = 1 << 2; 3375 3376 /* 3377 * If srtt exceeds .01 second, ensure we use the 'remote' MSL 3378 * Problem is: it doesn't work. Disabled by defaulting 3379 * tcp_rttlocal to 0; see corresponding code in 3380 * tcp_subr that selects local vs remote in a different way. 3381 * 3382 * The static branch prediction hint here should be removed 3383 * when the rtt estimator is fixed and the rtt_enable code 3384 * is turned back on. 3385 */ 3386 if (__predict_false(tcp_rttlocal) && tcp_msl_enable 3387 && tp->t_srtt > tcp_msl_remote_threshold 3388 && tp->t_msl < tcp_msl_remote) { 3389 tp->t_msl = tcp_msl_remote; 3390 } 3391 } else { 3392 /* 3393 * This is the first measurement. Per RFC2988, 2.2, 3394 * set rtt=R and srtt=R/2. 3395 * For srtt, storage representation is 1/32 ticks, 3396 * so shift left by 5. 3397 * For rttvar, storage representation is 1/16 ticks, 3398 * So shift left by 4, but then right by 1 to halve. 3399 */ 3400 tp->t_srtt = rtt << (TCP_RTT_SHIFT + 2); 3401 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT + 2 - 1); 3402 } 3403 tp->t_rtttime = 0; 3404 tp->t_rxtshift = 0; 3405 3406 /* 3407 * the retransmit should happen at rtt + 4 * rttvar. 3408 * Because of the way we do the smoothing, srtt and rttvar 3409 * will each average +1/2 tick of bias. When we compute 3410 * the retransmit timer, we want 1/2 tick of rounding and 3411 * 1 extra tick because of +-1/2 tick uncertainty in the 3412 * firing of the timer. The bias will give us exactly the 3413 * 1.5 tick we need. But, because the bias is 3414 * statistical, we have to test that we don't drop below 3415 * the minimum feasible timer (which is 2 ticks). 3416 */ 3417 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), 3418 max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX); 3419 3420 /* 3421 * We received an ack for a packet that wasn't retransmitted; 3422 * it is probably safe to discard any error indications we've 3423 * received recently. This isn't quite right, but close enough 3424 * for now (a route might have failed after we sent a segment, 3425 * and the return path might not be symmetrical). 3426 */ 3427 tp->t_softerror = 0; 3428 } 3429 3430 3431 /* 3432 * TCP compressed state engine. Currently used to hold compressed 3433 * state for SYN_RECEIVED. 3434 */ 3435 3436 u_long syn_cache_count; 3437 u_int32_t syn_hash1, syn_hash2; 3438 3439 #define SYN_HASH(sa, sp, dp) \ 3440 ((((sa)->s_addr^syn_hash1)*(((((u_int32_t)(dp))<<16) + \ 3441 ((u_int32_t)(sp)))^syn_hash2))) 3442 #ifndef INET6 3443 #define SYN_HASHALL(hash, src, dst) \ 3444 do { \ 3445 hash = SYN_HASH(&((const struct sockaddr_in *)(src))->sin_addr, \ 3446 ((const struct sockaddr_in *)(src))->sin_port, \ 3447 ((const struct sockaddr_in *)(dst))->sin_port); \ 3448 } while (/*CONSTCOND*/ 0) 3449 #else 3450 #define SYN_HASH6(sa, sp, dp) \ 3451 ((((sa)->s6_addr32[0] ^ (sa)->s6_addr32[3] ^ syn_hash1) * \ 3452 (((((u_int32_t)(dp))<<16) + ((u_int32_t)(sp)))^syn_hash2)) \ 3453 & 0x7fffffff) 3454 3455 #define SYN_HASHALL(hash, src, dst) \ 3456 do { \ 3457 switch ((src)->sa_family) { \ 3458 case AF_INET: \ 3459 hash = SYN_HASH(&((const struct sockaddr_in *)(src))->sin_addr, \ 3460 ((const struct sockaddr_in *)(src))->sin_port, \ 3461 ((const struct sockaddr_in *)(dst))->sin_port); \ 3462 break; \ 3463 case AF_INET6: \ 3464 hash = SYN_HASH6(&((const struct sockaddr_in6 *)(src))->sin6_addr, \ 3465 ((const struct sockaddr_in6 *)(src))->sin6_port, \ 3466 ((const struct sockaddr_in6 *)(dst))->sin6_port); \ 3467 break; \ 3468 default: \ 3469 hash = 0; \ 3470 } \ 3471 } while (/*CONSTCOND*/0) 3472 #endif /* INET6 */ 3473 3474 static struct pool syn_cache_pool; 3475 3476 /* 3477 * We don't estimate RTT with SYNs, so each packet starts with the default 3478 * RTT and each timer step has a fixed timeout value. 3479 */ 3480 static inline void 3481 syn_cache_timer_arm(struct syn_cache *sc) 3482 { 3483 3484 TCPT_RANGESET(sc->sc_rxtcur, 3485 TCPTV_SRTTDFLT * tcp_backoff[sc->sc_rxtshift], TCPTV_MIN, 3486 TCPTV_REXMTMAX); 3487 callout_reset(&sc->sc_timer, 3488 sc->sc_rxtcur * (hz / PR_SLOWHZ), syn_cache_timer, sc); 3489 } 3490 3491 #define SYN_CACHE_TIMESTAMP(sc) (tcp_now - (sc)->sc_timebase) 3492 3493 static inline void 3494 syn_cache_rm(struct syn_cache *sc) 3495 { 3496 TAILQ_REMOVE(&tcp_syn_cache[sc->sc_bucketidx].sch_bucket, 3497 sc, sc_bucketq); 3498 sc->sc_tp = NULL; 3499 LIST_REMOVE(sc, sc_tpq); 3500 tcp_syn_cache[sc->sc_bucketidx].sch_length--; 3501 callout_stop(&sc->sc_timer); 3502 syn_cache_count--; 3503 } 3504 3505 static inline void 3506 syn_cache_put(struct syn_cache *sc) 3507 { 3508 if (sc->sc_ipopts) 3509 (void) m_free(sc->sc_ipopts); 3510 rtcache_free(&sc->sc_route); 3511 sc->sc_flags |= SCF_DEAD; 3512 if (!callout_invoking(&sc->sc_timer)) 3513 callout_schedule(&(sc)->sc_timer, 1); 3514 } 3515 3516 void 3517 syn_cache_init(void) 3518 { 3519 int i; 3520 3521 pool_init(&syn_cache_pool, sizeof(struct syn_cache), 0, 0, 0, 3522 "synpl", NULL, IPL_SOFTNET); 3523 3524 /* Initialize the hash buckets. */ 3525 for (i = 0; i < tcp_syn_cache_size; i++) 3526 TAILQ_INIT(&tcp_syn_cache[i].sch_bucket); 3527 } 3528 3529 void 3530 syn_cache_insert(struct syn_cache *sc, struct tcpcb *tp) 3531 { 3532 struct syn_cache_head *scp; 3533 struct syn_cache *sc2; 3534 int s; 3535 3536 /* 3537 * If there are no entries in the hash table, reinitialize 3538 * the hash secrets. 3539 */ 3540 if (syn_cache_count == 0) { 3541 syn_hash1 = cprng_fast32(); 3542 syn_hash2 = cprng_fast32(); 3543 } 3544 3545 SYN_HASHALL(sc->sc_hash, &sc->sc_src.sa, &sc->sc_dst.sa); 3546 sc->sc_bucketidx = sc->sc_hash % tcp_syn_cache_size; 3547 scp = &tcp_syn_cache[sc->sc_bucketidx]; 3548 3549 /* 3550 * Make sure that we don't overflow the per-bucket 3551 * limit or the total cache size limit. 3552 */ 3553 s = splsoftnet(); 3554 if (scp->sch_length >= tcp_syn_bucket_limit) { 3555 TCP_STATINC(TCP_STAT_SC_BUCKETOVERFLOW); 3556 /* 3557 * The bucket is full. Toss the oldest element in the 3558 * bucket. This will be the first entry in the bucket. 3559 */ 3560 sc2 = TAILQ_FIRST(&scp->sch_bucket); 3561 #ifdef DIAGNOSTIC 3562 /* 3563 * This should never happen; we should always find an 3564 * entry in our bucket. 3565 */ 3566 if (sc2 == NULL) 3567 panic("syn_cache_insert: bucketoverflow: impossible"); 3568 #endif 3569 syn_cache_rm(sc2); 3570 syn_cache_put(sc2); /* calls pool_put but see spl above */ 3571 } else if (syn_cache_count >= tcp_syn_cache_limit) { 3572 struct syn_cache_head *scp2, *sce; 3573 3574 TCP_STATINC(TCP_STAT_SC_OVERFLOWED); 3575 /* 3576 * The cache is full. Toss the oldest entry in the 3577 * first non-empty bucket we can find. 3578 * 3579 * XXX We would really like to toss the oldest 3580 * entry in the cache, but we hope that this 3581 * condition doesn't happen very often. 3582 */ 3583 scp2 = scp; 3584 if (TAILQ_EMPTY(&scp2->sch_bucket)) { 3585 sce = &tcp_syn_cache[tcp_syn_cache_size]; 3586 for (++scp2; scp2 != scp; scp2++) { 3587 if (scp2 >= sce) 3588 scp2 = &tcp_syn_cache[0]; 3589 if (! TAILQ_EMPTY(&scp2->sch_bucket)) 3590 break; 3591 } 3592 #ifdef DIAGNOSTIC 3593 /* 3594 * This should never happen; we should always find a 3595 * non-empty bucket. 3596 */ 3597 if (scp2 == scp) 3598 panic("syn_cache_insert: cacheoverflow: " 3599 "impossible"); 3600 #endif 3601 } 3602 sc2 = TAILQ_FIRST(&scp2->sch_bucket); 3603 syn_cache_rm(sc2); 3604 syn_cache_put(sc2); /* calls pool_put but see spl above */ 3605 } 3606 3607 /* 3608 * Initialize the entry's timer. 3609 */ 3610 sc->sc_rxttot = 0; 3611 sc->sc_rxtshift = 0; 3612 syn_cache_timer_arm(sc); 3613 3614 /* Link it from tcpcb entry */ 3615 LIST_INSERT_HEAD(&tp->t_sc, sc, sc_tpq); 3616 3617 /* Put it into the bucket. */ 3618 TAILQ_INSERT_TAIL(&scp->sch_bucket, sc, sc_bucketq); 3619 scp->sch_length++; 3620 syn_cache_count++; 3621 3622 TCP_STATINC(TCP_STAT_SC_ADDED); 3623 splx(s); 3624 } 3625 3626 /* 3627 * Walk the timer queues, looking for SYN,ACKs that need to be retransmitted. 3628 * If we have retransmitted an entry the maximum number of times, expire 3629 * that entry. 3630 */ 3631 static void 3632 syn_cache_timer(void *arg) 3633 { 3634 struct syn_cache *sc = arg; 3635 3636 mutex_enter(softnet_lock); 3637 KERNEL_LOCK(1, NULL); 3638 3639 callout_ack(&sc->sc_timer); 3640 3641 if (__predict_false(sc->sc_flags & SCF_DEAD)) { 3642 TCP_STATINC(TCP_STAT_SC_DELAYED_FREE); 3643 goto free; 3644 } 3645 3646 if (__predict_false(sc->sc_rxtshift == TCP_MAXRXTSHIFT)) { 3647 /* Drop it -- too many retransmissions. */ 3648 goto dropit; 3649 } 3650 3651 /* 3652 * Compute the total amount of time this entry has 3653 * been on a queue. If this entry has been on longer 3654 * than the keep alive timer would allow, expire it. 3655 */ 3656 sc->sc_rxttot += sc->sc_rxtcur; 3657 if (sc->sc_rxttot >= tcp_keepinit) 3658 goto dropit; 3659 3660 TCP_STATINC(TCP_STAT_SC_RETRANSMITTED); 3661 (void)syn_cache_respond(sc); 3662 3663 /* Advance the timer back-off. */ 3664 sc->sc_rxtshift++; 3665 syn_cache_timer_arm(sc); 3666 3667 goto out; 3668 3669 dropit: 3670 TCP_STATINC(TCP_STAT_SC_TIMED_OUT); 3671 syn_cache_rm(sc); 3672 if (sc->sc_ipopts) 3673 (void) m_free(sc->sc_ipopts); 3674 rtcache_free(&sc->sc_route); 3675 3676 free: 3677 callout_destroy(&sc->sc_timer); 3678 pool_put(&syn_cache_pool, sc); 3679 3680 out: 3681 KERNEL_UNLOCK_ONE(NULL); 3682 mutex_exit(softnet_lock); 3683 } 3684 3685 /* 3686 * Remove syn cache created by the specified tcb entry, 3687 * because this does not make sense to keep them 3688 * (if there's no tcb entry, syn cache entry will never be used) 3689 */ 3690 void 3691 syn_cache_cleanup(struct tcpcb *tp) 3692 { 3693 struct syn_cache *sc, *nsc; 3694 int s; 3695 3696 s = splsoftnet(); 3697 3698 for (sc = LIST_FIRST(&tp->t_sc); sc != NULL; sc = nsc) { 3699 nsc = LIST_NEXT(sc, sc_tpq); 3700 3701 #ifdef DIAGNOSTIC 3702 if (sc->sc_tp != tp) 3703 panic("invalid sc_tp in syn_cache_cleanup"); 3704 #endif 3705 syn_cache_rm(sc); 3706 syn_cache_put(sc); /* calls pool_put but see spl above */ 3707 } 3708 /* just for safety */ 3709 LIST_INIT(&tp->t_sc); 3710 3711 splx(s); 3712 } 3713 3714 /* 3715 * Find an entry in the syn cache. 3716 */ 3717 struct syn_cache * 3718 syn_cache_lookup(const struct sockaddr *src, const struct sockaddr *dst, 3719 struct syn_cache_head **headp) 3720 { 3721 struct syn_cache *sc; 3722 struct syn_cache_head *scp; 3723 u_int32_t hash; 3724 int s; 3725 3726 SYN_HASHALL(hash, src, dst); 3727 3728 scp = &tcp_syn_cache[hash % tcp_syn_cache_size]; 3729 *headp = scp; 3730 s = splsoftnet(); 3731 for (sc = TAILQ_FIRST(&scp->sch_bucket); sc != NULL; 3732 sc = TAILQ_NEXT(sc, sc_bucketq)) { 3733 if (sc->sc_hash != hash) 3734 continue; 3735 if (!memcmp(&sc->sc_src, src, src->sa_len) && 3736 !memcmp(&sc->sc_dst, dst, dst->sa_len)) { 3737 splx(s); 3738 return (sc); 3739 } 3740 } 3741 splx(s); 3742 return (NULL); 3743 } 3744 3745 /* 3746 * This function gets called when we receive an ACK for a socket in the 3747 * LISTEN state. We look up the connection in the syn cache, and if it's 3748 * there, we pull it out of the cache and turn it into a full-blown 3749 * connection in the SYN-RECEIVED state. 3750 * 3751 * The return values may not be immediately obvious, and their effects 3752 * can be subtle, so here they are: 3753 * 3754 * NULL SYN was not found in cache; caller should drop the 3755 * packet and send an RST. 3756 * 3757 * -1 We were unable to create the new connection, and are 3758 * aborting it. An ACK,RST is being sent to the peer 3759 * (unless we got screwey sequence numbers; see below), 3760 * because the 3-way handshake has been completed. Caller 3761 * should not free the mbuf, since we may be using it. If 3762 * we are not, we will free it. 3763 * 3764 * Otherwise, the return value is a pointer to the new socket 3765 * associated with the connection. 3766 */ 3767 struct socket * 3768 syn_cache_get(struct sockaddr *src, struct sockaddr *dst, 3769 struct tcphdr *th, struct socket *so, struct mbuf *m) 3770 { 3771 struct syn_cache *sc; 3772 struct syn_cache_head *scp; 3773 struct inpcb *inp = NULL; 3774 #ifdef INET6 3775 struct in6pcb *in6p = NULL; 3776 #endif 3777 struct tcpcb *tp; 3778 int s; 3779 struct socket *oso; 3780 3781 s = splsoftnet(); 3782 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 3783 splx(s); 3784 return NULL; 3785 } 3786 3787 /* 3788 * Verify the sequence and ack numbers. Try getting the correct 3789 * response again. 3790 */ 3791 if ((th->th_ack != sc->sc_iss + 1) || 3792 SEQ_LEQ(th->th_seq, sc->sc_irs) || 3793 SEQ_GT(th->th_seq, sc->sc_irs + 1 + sc->sc_win)) { 3794 m_freem(m); 3795 (void)syn_cache_respond(sc); 3796 splx(s); 3797 return ((struct socket *)(-1)); 3798 } 3799 3800 /* Remove this cache entry */ 3801 syn_cache_rm(sc); 3802 splx(s); 3803 3804 /* 3805 * Ok, create the full blown connection, and set things up 3806 * as they would have been set up if we had created the 3807 * connection when the SYN arrived. If we can't create 3808 * the connection, abort it. 3809 */ 3810 /* 3811 * inp still has the OLD in_pcb stuff, set the 3812 * v6-related flags on the new guy, too. This is 3813 * done particularly for the case where an AF_INET6 3814 * socket is bound only to a port, and a v4 connection 3815 * comes in on that port. 3816 * we also copy the flowinfo from the original pcb 3817 * to the new one. 3818 */ 3819 oso = so; 3820 so = sonewconn(so, true); 3821 if (so == NULL) 3822 goto resetandabort; 3823 3824 switch (so->so_proto->pr_domain->dom_family) { 3825 case AF_INET: 3826 inp = sotoinpcb(so); 3827 break; 3828 #ifdef INET6 3829 case AF_INET6: 3830 in6p = sotoin6pcb(so); 3831 break; 3832 #endif 3833 } 3834 3835 switch (src->sa_family) { 3836 case AF_INET: 3837 if (inp) { 3838 inp->inp_laddr = ((struct sockaddr_in *)dst)->sin_addr; 3839 inp->inp_lport = ((struct sockaddr_in *)dst)->sin_port; 3840 inp->inp_options = ip_srcroute(m); 3841 in_pcbstate(inp, INP_BOUND); 3842 if (inp->inp_options == NULL) { 3843 inp->inp_options = sc->sc_ipopts; 3844 sc->sc_ipopts = NULL; 3845 } 3846 } 3847 #ifdef INET6 3848 else if (in6p) { 3849 /* IPv4 packet to AF_INET6 socket */ 3850 memset(&in6p->in6p_laddr, 0, sizeof(in6p->in6p_laddr)); 3851 in6p->in6p_laddr.s6_addr16[5] = htons(0xffff); 3852 bcopy(&((struct sockaddr_in *)dst)->sin_addr, 3853 &in6p->in6p_laddr.s6_addr32[3], 3854 sizeof(((struct sockaddr_in *)dst)->sin_addr)); 3855 in6p->in6p_lport = ((struct sockaddr_in *)dst)->sin_port; 3856 in6totcpcb(in6p)->t_family = AF_INET; 3857 if (sotoin6pcb(oso)->in6p_flags & IN6P_IPV6_V6ONLY) 3858 in6p->in6p_flags |= IN6P_IPV6_V6ONLY; 3859 else 3860 in6p->in6p_flags &= ~IN6P_IPV6_V6ONLY; 3861 in6_pcbstate(in6p, IN6P_BOUND); 3862 } 3863 #endif 3864 break; 3865 #ifdef INET6 3866 case AF_INET6: 3867 if (in6p) { 3868 in6p->in6p_laddr = ((struct sockaddr_in6 *)dst)->sin6_addr; 3869 in6p->in6p_lport = ((struct sockaddr_in6 *)dst)->sin6_port; 3870 in6_pcbstate(in6p, IN6P_BOUND); 3871 } 3872 break; 3873 #endif 3874 } 3875 3876 #ifdef INET6 3877 if (in6p && in6totcpcb(in6p)->t_family == AF_INET6 && sotoinpcb(oso)) { 3878 struct in6pcb *oin6p = sotoin6pcb(oso); 3879 /* inherit socket options from the listening socket */ 3880 in6p->in6p_flags |= (oin6p->in6p_flags & IN6P_CONTROLOPTS); 3881 if (in6p->in6p_flags & IN6P_CONTROLOPTS) { 3882 m_freem(in6p->in6p_options); 3883 in6p->in6p_options = NULL; 3884 } 3885 ip6_savecontrol(in6p, &in6p->in6p_options, 3886 mtod(m, struct ip6_hdr *), m); 3887 } 3888 #endif 3889 3890 /* 3891 * Give the new socket our cached route reference. 3892 */ 3893 if (inp) { 3894 rtcache_copy(&inp->inp_route, &sc->sc_route); 3895 rtcache_free(&sc->sc_route); 3896 } 3897 #ifdef INET6 3898 else { 3899 rtcache_copy(&in6p->in6p_route, &sc->sc_route); 3900 rtcache_free(&sc->sc_route); 3901 } 3902 #endif 3903 3904 if (inp) { 3905 struct sockaddr_in sin; 3906 memcpy(&sin, src, src->sa_len); 3907 if (in_pcbconnect(inp, &sin, &lwp0)) { 3908 goto resetandabort; 3909 } 3910 } 3911 #ifdef INET6 3912 else if (in6p) { 3913 struct sockaddr_in6 sin6; 3914 memcpy(&sin6, src, src->sa_len); 3915 if (src->sa_family == AF_INET) { 3916 /* IPv4 packet to AF_INET6 socket */ 3917 in6_sin_2_v4mapsin6((struct sockaddr_in *)src, &sin6); 3918 } 3919 if (in6_pcbconnect(in6p, &sin6, NULL)) { 3920 goto resetandabort; 3921 } 3922 } 3923 #endif 3924 else { 3925 goto resetandabort; 3926 } 3927 3928 if (inp) 3929 tp = intotcpcb(inp); 3930 #ifdef INET6 3931 else if (in6p) 3932 tp = in6totcpcb(in6p); 3933 #endif 3934 else 3935 tp = NULL; 3936 3937 tp->t_flags = sototcpcb(oso)->t_flags & TF_NODELAY; 3938 if (sc->sc_request_r_scale != 15) { 3939 tp->requested_s_scale = sc->sc_requested_s_scale; 3940 tp->request_r_scale = sc->sc_request_r_scale; 3941 tp->snd_scale = sc->sc_requested_s_scale; 3942 tp->rcv_scale = sc->sc_request_r_scale; 3943 tp->t_flags |= TF_REQ_SCALE|TF_RCVD_SCALE; 3944 } 3945 if (sc->sc_flags & SCF_TIMESTAMP) 3946 tp->t_flags |= TF_REQ_TSTMP|TF_RCVD_TSTMP; 3947 tp->ts_timebase = sc->sc_timebase; 3948 3949 tp->t_template = tcp_template(tp); 3950 if (tp->t_template == 0) { 3951 tp = tcp_drop(tp, ENOBUFS); /* destroys socket */ 3952 so = NULL; 3953 m_freem(m); 3954 goto abort; 3955 } 3956 3957 tp->iss = sc->sc_iss; 3958 tp->irs = sc->sc_irs; 3959 tcp_sendseqinit(tp); 3960 tcp_rcvseqinit(tp); 3961 tp->t_state = TCPS_SYN_RECEIVED; 3962 TCP_TIMER_ARM(tp, TCPT_KEEP, tp->t_keepinit); 3963 TCP_STATINC(TCP_STAT_ACCEPTS); 3964 3965 if ((sc->sc_flags & SCF_SACK_PERMIT) && tcp_do_sack) 3966 tp->t_flags |= TF_WILL_SACK; 3967 3968 if ((sc->sc_flags & SCF_ECN_PERMIT) && tcp_do_ecn) 3969 tp->t_flags |= TF_ECN_PERMIT; 3970 3971 #ifdef TCP_SIGNATURE 3972 if (sc->sc_flags & SCF_SIGNATURE) 3973 tp->t_flags |= TF_SIGNATURE; 3974 #endif 3975 3976 /* Initialize tp->t_ourmss before we deal with the peer's! */ 3977 tp->t_ourmss = sc->sc_ourmaxseg; 3978 tcp_mss_from_peer(tp, sc->sc_peermaxseg); 3979 3980 /* 3981 * Initialize the initial congestion window. If we 3982 * had to retransmit the SYN,ACK, we must initialize cwnd 3983 * to 1 segment (i.e. the Loss Window). 3984 */ 3985 if (sc->sc_rxtshift) 3986 tp->snd_cwnd = tp->t_peermss; 3987 else { 3988 int ss = tcp_init_win; 3989 if (inp != NULL && in_localaddr(inp->inp_faddr)) 3990 ss = tcp_init_win_local; 3991 #ifdef INET6 3992 if (in6p != NULL && in6_localaddr(&in6p->in6p_faddr)) 3993 ss = tcp_init_win_local; 3994 #endif 3995 tp->snd_cwnd = TCP_INITIAL_WINDOW(ss, tp->t_peermss); 3996 } 3997 3998 tcp_rmx_rtt(tp); 3999 tp->snd_wl1 = sc->sc_irs; 4000 tp->rcv_up = sc->sc_irs + 1; 4001 4002 /* 4003 * This is what whould have happened in tcp_output() when 4004 * the SYN,ACK was sent. 4005 */ 4006 tp->snd_up = tp->snd_una; 4007 tp->snd_max = tp->snd_nxt = tp->iss+1; 4008 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 4009 if (sc->sc_win > 0 && SEQ_GT(tp->rcv_nxt + sc->sc_win, tp->rcv_adv)) 4010 tp->rcv_adv = tp->rcv_nxt + sc->sc_win; 4011 tp->last_ack_sent = tp->rcv_nxt; 4012 tp->t_partialacks = -1; 4013 tp->t_dupacks = 0; 4014 4015 TCP_STATINC(TCP_STAT_SC_COMPLETED); 4016 s = splsoftnet(); 4017 syn_cache_put(sc); 4018 splx(s); 4019 return so; 4020 4021 resetandabort: 4022 (void)tcp_respond(NULL, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 4023 abort: 4024 if (so != NULL) { 4025 (void) soqremque(so, 1); 4026 (void) soabort(so); 4027 mutex_enter(softnet_lock); 4028 } 4029 s = splsoftnet(); 4030 syn_cache_put(sc); 4031 splx(s); 4032 TCP_STATINC(TCP_STAT_SC_ABORTED); 4033 return ((struct socket *)(-1)); 4034 } 4035 4036 /* 4037 * This function is called when we get a RST for a 4038 * non-existent connection, so that we can see if the 4039 * connection is in the syn cache. If it is, zap it. 4040 */ 4041 4042 void 4043 syn_cache_reset(struct sockaddr *src, struct sockaddr *dst, struct tcphdr *th) 4044 { 4045 struct syn_cache *sc; 4046 struct syn_cache_head *scp; 4047 int s = splsoftnet(); 4048 4049 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 4050 splx(s); 4051 return; 4052 } 4053 if (SEQ_LT(th->th_seq, sc->sc_irs) || 4054 SEQ_GT(th->th_seq, sc->sc_irs+1)) { 4055 splx(s); 4056 return; 4057 } 4058 syn_cache_rm(sc); 4059 TCP_STATINC(TCP_STAT_SC_RESET); 4060 syn_cache_put(sc); /* calls pool_put but see spl above */ 4061 splx(s); 4062 } 4063 4064 void 4065 syn_cache_unreach(const struct sockaddr *src, const struct sockaddr *dst, 4066 struct tcphdr *th) 4067 { 4068 struct syn_cache *sc; 4069 struct syn_cache_head *scp; 4070 int s; 4071 4072 s = splsoftnet(); 4073 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 4074 splx(s); 4075 return; 4076 } 4077 /* If the sequence number != sc_iss, then it's a bogus ICMP msg */ 4078 if (ntohl(th->th_seq) != sc->sc_iss) { 4079 splx(s); 4080 return; 4081 } 4082 4083 /* 4084 * If we've retransmitted 3 times and this is our second error, 4085 * we remove the entry. Otherwise, we allow it to continue on. 4086 * This prevents us from incorrectly nuking an entry during a 4087 * spurious network outage. 4088 * 4089 * See tcp_notify(). 4090 */ 4091 if ((sc->sc_flags & SCF_UNREACH) == 0 || sc->sc_rxtshift < 3) { 4092 sc->sc_flags |= SCF_UNREACH; 4093 splx(s); 4094 return; 4095 } 4096 4097 syn_cache_rm(sc); 4098 TCP_STATINC(TCP_STAT_SC_UNREACH); 4099 syn_cache_put(sc); /* calls pool_put but see spl above */ 4100 splx(s); 4101 } 4102 4103 /* 4104 * Given a LISTEN socket and an inbound SYN request, add this to the syn 4105 * cache, and send back a segment: 4106 * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK> 4107 * to the source. 4108 * 4109 * IMPORTANT NOTE: We do _NOT_ ACK data that might accompany the SYN. 4110 * Doing so would require that we hold onto the data and deliver it 4111 * to the application. However, if we are the target of a SYN-flood 4112 * DoS attack, an attacker could send data which would eventually 4113 * consume all available buffer space if it were ACKed. By not ACKing 4114 * the data, we avoid this DoS scenario. 4115 */ 4116 int 4117 syn_cache_add(struct sockaddr *src, struct sockaddr *dst, struct tcphdr *th, 4118 unsigned int toff, struct socket *so, struct mbuf *m, u_char *optp, 4119 int optlen, struct tcp_opt_info *oi) 4120 { 4121 struct tcpcb tb, *tp; 4122 long win; 4123 struct syn_cache *sc; 4124 struct syn_cache_head *scp; 4125 struct mbuf *ipopts; 4126 int s; 4127 4128 tp = sototcpcb(so); 4129 4130 /* 4131 * Initialize some local state. 4132 */ 4133 win = sbspace(&so->so_rcv); 4134 if (win > TCP_MAXWIN) 4135 win = TCP_MAXWIN; 4136 4137 #ifdef TCP_SIGNATURE 4138 if (optp || (tp->t_flags & TF_SIGNATURE)) 4139 #else 4140 if (optp) 4141 #endif 4142 { 4143 tb.t_flags = tcp_do_rfc1323 ? (TF_REQ_SCALE|TF_REQ_TSTMP) : 0; 4144 #ifdef TCP_SIGNATURE 4145 tb.t_flags |= (tp->t_flags & TF_SIGNATURE); 4146 #endif 4147 tb.t_state = TCPS_LISTEN; 4148 if (tcp_dooptions(&tb, optp, optlen, th, m, toff, oi) < 0) 4149 return 0; 4150 } else 4151 tb.t_flags = 0; 4152 4153 switch (src->sa_family) { 4154 case AF_INET: 4155 /* Remember the IP options, if any. */ 4156 ipopts = ip_srcroute(m); 4157 break; 4158 default: 4159 ipopts = NULL; 4160 } 4161 4162 /* 4163 * See if we already have an entry for this connection. 4164 * If we do, resend the SYN,ACK. We do not count this 4165 * as a retransmission (XXX though maybe we should). 4166 */ 4167 if ((sc = syn_cache_lookup(src, dst, &scp)) != NULL) { 4168 TCP_STATINC(TCP_STAT_SC_DUPESYN); 4169 if (ipopts) { 4170 /* 4171 * If we were remembering a previous source route, 4172 * forget it and use the new one we've been given. 4173 */ 4174 if (sc->sc_ipopts) 4175 (void)m_free(sc->sc_ipopts); 4176 sc->sc_ipopts = ipopts; 4177 } 4178 sc->sc_timestamp = tb.ts_recent; 4179 m_freem(m); 4180 if (syn_cache_respond(sc) == 0) { 4181 uint64_t *tcps = TCP_STAT_GETREF(); 4182 tcps[TCP_STAT_SNDACKS]++; 4183 tcps[TCP_STAT_SNDTOTAL]++; 4184 TCP_STAT_PUTREF(); 4185 } 4186 return 1; 4187 } 4188 4189 s = splsoftnet(); 4190 sc = pool_get(&syn_cache_pool, PR_NOWAIT); 4191 splx(s); 4192 if (sc == NULL) { 4193 if (ipopts) 4194 (void)m_free(ipopts); 4195 return 0; 4196 } 4197 4198 /* 4199 * Fill in the cache, and put the necessary IP and TCP 4200 * options into the reply. 4201 */ 4202 memset(sc, 0, sizeof(struct syn_cache)); 4203 callout_init(&sc->sc_timer, CALLOUT_MPSAFE); 4204 memcpy(&sc->sc_src, src, src->sa_len); 4205 memcpy(&sc->sc_dst, dst, dst->sa_len); 4206 sc->sc_flags = 0; 4207 sc->sc_ipopts = ipopts; 4208 sc->sc_irs = th->th_seq; 4209 switch (src->sa_family) { 4210 case AF_INET: 4211 { 4212 struct sockaddr_in *srcin = (void *)src; 4213 struct sockaddr_in *dstin = (void *)dst; 4214 4215 sc->sc_iss = tcp_new_iss1(&dstin->sin_addr, 4216 &srcin->sin_addr, dstin->sin_port, 4217 srcin->sin_port, sizeof(dstin->sin_addr), 0); 4218 break; 4219 } 4220 #ifdef INET6 4221 case AF_INET6: 4222 { 4223 struct sockaddr_in6 *srcin6 = (void *)src; 4224 struct sockaddr_in6 *dstin6 = (void *)dst; 4225 4226 sc->sc_iss = tcp_new_iss1(&dstin6->sin6_addr, 4227 &srcin6->sin6_addr, dstin6->sin6_port, 4228 srcin6->sin6_port, sizeof(dstin6->sin6_addr), 0); 4229 break; 4230 } 4231 #endif 4232 } 4233 sc->sc_peermaxseg = oi->maxseg; 4234 sc->sc_ourmaxseg = tcp_mss_to_advertise(m->m_flags & M_PKTHDR ? 4235 m_get_rcvif_NOMPSAFE(m) : NULL, sc->sc_src.sa.sa_family); 4236 sc->sc_win = win; 4237 sc->sc_timebase = tcp_now - 1; /* see tcp_newtcpcb() */ 4238 sc->sc_timestamp = tb.ts_recent; 4239 if ((tb.t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP)) == 4240 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) 4241 sc->sc_flags |= SCF_TIMESTAMP; 4242 if ((tb.t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 4243 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 4244 sc->sc_requested_s_scale = tb.requested_s_scale; 4245 sc->sc_request_r_scale = 0; 4246 /* 4247 * Pick the smallest possible scaling factor that 4248 * will still allow us to scale up to sb_max. 4249 * 4250 * We do this because there are broken firewalls that 4251 * will corrupt the window scale option, leading to 4252 * the other endpoint believing that our advertised 4253 * window is unscaled. At scale factors larger than 4254 * 5 the unscaled window will drop below 1500 bytes, 4255 * leading to serious problems when traversing these 4256 * broken firewalls. 4257 * 4258 * With the default sbmax of 256K, a scale factor 4259 * of 3 will be chosen by this algorithm. Those who 4260 * choose a larger sbmax should watch out 4261 * for the compatiblity problems mentioned above. 4262 * 4263 * RFC1323: The Window field in a SYN (i.e., a <SYN> 4264 * or <SYN,ACK>) segment itself is never scaled. 4265 */ 4266 while (sc->sc_request_r_scale < TCP_MAX_WINSHIFT && 4267 (TCP_MAXWIN << sc->sc_request_r_scale) < sb_max) 4268 sc->sc_request_r_scale++; 4269 } else { 4270 sc->sc_requested_s_scale = 15; 4271 sc->sc_request_r_scale = 15; 4272 } 4273 if ((tb.t_flags & TF_SACK_PERMIT) && tcp_do_sack) 4274 sc->sc_flags |= SCF_SACK_PERMIT; 4275 4276 /* 4277 * ECN setup packet received. 4278 */ 4279 if ((th->th_flags & (TH_ECE|TH_CWR)) && tcp_do_ecn) 4280 sc->sc_flags |= SCF_ECN_PERMIT; 4281 4282 #ifdef TCP_SIGNATURE 4283 if (tb.t_flags & TF_SIGNATURE) 4284 sc->sc_flags |= SCF_SIGNATURE; 4285 #endif 4286 sc->sc_tp = tp; 4287 m_freem(m); 4288 if (syn_cache_respond(sc) == 0) { 4289 uint64_t *tcps = TCP_STAT_GETREF(); 4290 tcps[TCP_STAT_SNDACKS]++; 4291 tcps[TCP_STAT_SNDTOTAL]++; 4292 TCP_STAT_PUTREF(); 4293 syn_cache_insert(sc, tp); 4294 } else { 4295 s = splsoftnet(); 4296 /* 4297 * syn_cache_put() will try to schedule the timer, so 4298 * we need to initialize it 4299 */ 4300 syn_cache_timer_arm(sc); 4301 syn_cache_put(sc); 4302 splx(s); 4303 TCP_STATINC(TCP_STAT_SC_DROPPED); 4304 } 4305 return 1; 4306 } 4307 4308 /* 4309 * syn_cache_respond: (re)send SYN+ACK. 4310 * 4311 * Returns 0 on success. 4312 */ 4313 4314 int 4315 syn_cache_respond(struct syn_cache *sc) 4316 { 4317 #ifdef INET6 4318 struct rtentry *rt = NULL; 4319 #endif 4320 struct route *ro; 4321 u_int8_t *optp; 4322 int optlen, error; 4323 u_int16_t tlen; 4324 struct ip *ip = NULL; 4325 #ifdef INET6 4326 struct ip6_hdr *ip6 = NULL; 4327 #endif 4328 struct tcpcb *tp; 4329 struct tcphdr *th; 4330 struct mbuf *m; 4331 u_int hlen; 4332 #ifdef TCP_SIGNATURE 4333 struct secasvar *sav = NULL; 4334 u_int8_t *sigp = NULL; 4335 #endif 4336 4337 ro = &sc->sc_route; 4338 switch (sc->sc_src.sa.sa_family) { 4339 case AF_INET: 4340 hlen = sizeof(struct ip); 4341 break; 4342 #ifdef INET6 4343 case AF_INET6: 4344 hlen = sizeof(struct ip6_hdr); 4345 break; 4346 #endif 4347 default: 4348 return EAFNOSUPPORT; 4349 } 4350 4351 /* Worst case scanario, since we don't know the option size yet. */ 4352 tlen = hlen + sizeof(struct tcphdr) + MAX_TCPOPTLEN; 4353 KASSERT(max_linkhdr + tlen <= MCLBYTES); 4354 4355 /* 4356 * Create the IP+TCP header from scratch. 4357 */ 4358 MGETHDR(m, M_DONTWAIT, MT_DATA); 4359 if (m && (max_linkhdr + tlen) > MHLEN) { 4360 MCLGET(m, M_DONTWAIT); 4361 if ((m->m_flags & M_EXT) == 0) { 4362 m_freem(m); 4363 m = NULL; 4364 } 4365 } 4366 if (m == NULL) 4367 return ENOBUFS; 4368 MCLAIM(m, &tcp_tx_mowner); 4369 4370 tp = sc->sc_tp; 4371 4372 /* Fixup the mbuf. */ 4373 m->m_data += max_linkhdr; 4374 m_reset_rcvif(m); 4375 memset(mtod(m, void *), 0, tlen); 4376 4377 switch (sc->sc_src.sa.sa_family) { 4378 case AF_INET: 4379 ip = mtod(m, struct ip *); 4380 ip->ip_v = 4; 4381 ip->ip_dst = sc->sc_src.sin.sin_addr; 4382 ip->ip_src = sc->sc_dst.sin.sin_addr; 4383 ip->ip_p = IPPROTO_TCP; 4384 th = (struct tcphdr *)(ip + 1); 4385 th->th_dport = sc->sc_src.sin.sin_port; 4386 th->th_sport = sc->sc_dst.sin.sin_port; 4387 break; 4388 #ifdef INET6 4389 case AF_INET6: 4390 ip6 = mtod(m, struct ip6_hdr *); 4391 ip6->ip6_vfc = IPV6_VERSION; 4392 ip6->ip6_dst = sc->sc_src.sin6.sin6_addr; 4393 ip6->ip6_src = sc->sc_dst.sin6.sin6_addr; 4394 ip6->ip6_nxt = IPPROTO_TCP; 4395 /* ip6_plen will be updated in ip6_output() */ 4396 th = (struct tcphdr *)(ip6 + 1); 4397 th->th_dport = sc->sc_src.sin6.sin6_port; 4398 th->th_sport = sc->sc_dst.sin6.sin6_port; 4399 break; 4400 #endif 4401 default: 4402 panic("%s: impossible (1)", __func__); 4403 } 4404 4405 th->th_seq = htonl(sc->sc_iss); 4406 th->th_ack = htonl(sc->sc_irs + 1); 4407 th->th_flags = TH_SYN|TH_ACK; 4408 th->th_win = htons(sc->sc_win); 4409 /* th_x2, th_sum, th_urp already 0 from memset */ 4410 4411 /* Tack on the TCP options. */ 4412 optp = (u_int8_t *)(th + 1); 4413 optlen = 0; 4414 *optp++ = TCPOPT_MAXSEG; 4415 *optp++ = TCPOLEN_MAXSEG; 4416 *optp++ = (sc->sc_ourmaxseg >> 8) & 0xff; 4417 *optp++ = sc->sc_ourmaxseg & 0xff; 4418 optlen += TCPOLEN_MAXSEG; 4419 4420 if (sc->sc_request_r_scale != 15) { 4421 *((u_int32_t *)optp) = htonl(TCPOPT_NOP << 24 | 4422 TCPOPT_WINDOW << 16 | TCPOLEN_WINDOW << 8 | 4423 sc->sc_request_r_scale); 4424 optp += TCPOLEN_WINDOW + TCPOLEN_NOP; 4425 optlen += TCPOLEN_WINDOW + TCPOLEN_NOP; 4426 } 4427 4428 if (sc->sc_flags & SCF_SACK_PERMIT) { 4429 /* Let the peer know that we will SACK. */ 4430 *optp++ = TCPOPT_SACK_PERMITTED; 4431 *optp++ = TCPOLEN_SACK_PERMITTED; 4432 optlen += TCPOLEN_SACK_PERMITTED; 4433 } 4434 4435 if (sc->sc_flags & SCF_TIMESTAMP) { 4436 while (optlen % 4 != 2) { 4437 optlen += TCPOLEN_NOP; 4438 *optp++ = TCPOPT_NOP; 4439 } 4440 *optp++ = TCPOPT_TIMESTAMP; 4441 *optp++ = TCPOLEN_TIMESTAMP; 4442 u_int32_t *lp = (u_int32_t *)(optp); 4443 /* Form timestamp option as shown in appendix A of RFC 1323. */ 4444 *lp++ = htonl(SYN_CACHE_TIMESTAMP(sc)); 4445 *lp = htonl(sc->sc_timestamp); 4446 optp += TCPOLEN_TIMESTAMP - 2; 4447 optlen += TCPOLEN_TIMESTAMP; 4448 } 4449 4450 #ifdef TCP_SIGNATURE 4451 if (sc->sc_flags & SCF_SIGNATURE) { 4452 sav = tcp_signature_getsav(m); 4453 if (sav == NULL) { 4454 m_freem(m); 4455 return EPERM; 4456 } 4457 4458 *optp++ = TCPOPT_SIGNATURE; 4459 *optp++ = TCPOLEN_SIGNATURE; 4460 sigp = optp; 4461 memset(optp, 0, TCP_SIGLEN); 4462 optp += TCP_SIGLEN; 4463 optlen += TCPOLEN_SIGNATURE; 4464 } 4465 #endif 4466 4467 /* 4468 * Terminate and pad TCP options to a 4 byte boundary. 4469 * 4470 * According to RFC793: "The content of the header beyond the 4471 * End-of-Option option must be header padding (i.e., zero)." 4472 * And later: "The padding is composed of zeros." 4473 */ 4474 if (optlen % 4) { 4475 optlen += TCPOLEN_EOL; 4476 *optp++ = TCPOPT_EOL; 4477 } 4478 while (optlen % 4) { 4479 optlen += TCPOLEN_PAD; 4480 *optp++ = TCPOPT_PAD; 4481 } 4482 4483 /* Compute the actual values now that we've added the options. */ 4484 tlen = hlen + sizeof(struct tcphdr) + optlen; 4485 m->m_len = m->m_pkthdr.len = tlen; 4486 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 4487 4488 #ifdef TCP_SIGNATURE 4489 if (sav) { 4490 (void)tcp_signature(m, th, hlen, sav, sigp); 4491 key_sa_recordxfer(sav, m); 4492 KEY_SA_UNREF(&sav); 4493 } 4494 #endif 4495 4496 /* 4497 * Send ECN SYN-ACK setup packet. 4498 * Routes can be asymetric, so, even if we receive a packet 4499 * with ECE and CWR set, we must not assume no one will block 4500 * the ECE packet we are about to send. 4501 */ 4502 if ((sc->sc_flags & SCF_ECN_PERMIT) && tp && 4503 SEQ_GEQ(tp->snd_nxt, tp->snd_max)) { 4504 th->th_flags |= TH_ECE; 4505 TCP_STATINC(TCP_STAT_ECN_SHS); 4506 4507 /* 4508 * draft-ietf-tcpm-ecnsyn-00.txt 4509 * 4510 * "[...] a TCP node MAY respond to an ECN-setup 4511 * SYN packet by setting ECT in the responding 4512 * ECN-setup SYN/ACK packet, indicating to routers 4513 * that the SYN/ACK packet is ECN-Capable. 4514 * This allows a congested router along the path 4515 * to mark the packet instead of dropping the 4516 * packet as an indication of congestion." 4517 * 4518 * "[...] There can be a great benefit in setting 4519 * an ECN-capable codepoint in SYN/ACK packets [...] 4520 * Congestion is most likely to occur in 4521 * the server-to-client direction. As a result, 4522 * setting an ECN-capable codepoint in SYN/ACK 4523 * packets can reduce the occurence of three-second 4524 * retransmit timeouts resulting from the drop 4525 * of SYN/ACK packets." 4526 * 4527 * Page 4 and 6, January 2006. 4528 */ 4529 4530 switch (sc->sc_src.sa.sa_family) { 4531 case AF_INET: 4532 ip->ip_tos |= IPTOS_ECN_ECT0; 4533 break; 4534 #ifdef INET6 4535 case AF_INET6: 4536 ip6->ip6_flow |= htonl(IPTOS_ECN_ECT0 << 20); 4537 break; 4538 #endif 4539 } 4540 TCP_STATINC(TCP_STAT_ECN_ECT); 4541 } 4542 4543 4544 /* 4545 * Compute the packet's checksum. 4546 * 4547 * Fill in some straggling IP bits. Note the stack expects 4548 * ip_len to be in host order, for convenience. 4549 */ 4550 switch (sc->sc_src.sa.sa_family) { 4551 case AF_INET: 4552 ip->ip_len = htons(tlen - hlen); 4553 th->th_sum = 0; 4554 th->th_sum = in4_cksum(m, IPPROTO_TCP, hlen, tlen - hlen); 4555 ip->ip_len = htons(tlen); 4556 ip->ip_ttl = ip_defttl; 4557 /* XXX tos? */ 4558 break; 4559 #ifdef INET6 4560 case AF_INET6: 4561 ip6->ip6_plen = htons(tlen - hlen); 4562 th->th_sum = 0; 4563 th->th_sum = in6_cksum(m, IPPROTO_TCP, hlen, tlen - hlen); 4564 ip6->ip6_vfc &= ~IPV6_VERSION_MASK; 4565 ip6->ip6_vfc |= IPV6_VERSION; 4566 ip6->ip6_plen = htons(tlen - hlen); 4567 /* ip6_hlim will be initialized afterwards */ 4568 /* XXX flowlabel? */ 4569 break; 4570 #endif 4571 } 4572 4573 /* XXX use IPsec policy on listening socket, on SYN ACK */ 4574 tp = sc->sc_tp; 4575 4576 switch (sc->sc_src.sa.sa_family) { 4577 case AF_INET: 4578 error = ip_output(m, sc->sc_ipopts, ro, 4579 (ip_mtudisc ? IP_MTUDISC : 0), 4580 NULL, tp ? tp->t_inpcb : NULL); 4581 break; 4582 #ifdef INET6 4583 case AF_INET6: 4584 ip6->ip6_hlim = in6_selecthlim(NULL, 4585 (rt = rtcache_validate(ro)) != NULL ? rt->rt_ifp : NULL); 4586 rtcache_unref(rt, ro); 4587 4588 error = ip6_output(m, NULL /*XXX*/, ro, 0, NULL, 4589 tp ? tp->t_in6pcb : NULL, NULL); 4590 break; 4591 #endif 4592 default: 4593 panic("%s: impossible (2)", __func__); 4594 } 4595 4596 return error; 4597 } 4598