1 /* 2 * Copyright (c) 2003, 2004 Jeffrey M. Hsu. All rights reserved. 3 * Copyright (c) 2003, 2004 The DragonFly Project. All rights reserved. 4 * 5 * This code is derived from software contributed to The DragonFly Project 6 * by Jeffrey M. Hsu. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. Neither the name of The DragonFly Project nor the names of its 17 * contributors may be used to endorse or promote products derived 18 * from this software without specific, prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 22 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 23 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 24 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 25 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 26 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 27 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 28 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 29 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 30 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 /* 35 * All advertising materials mentioning features or use of this software 36 * must display the following acknowledgement: 37 * This product includes software developed by Jeffrey M. Hsu. 38 * 39 * Copyright (c) 2001 Networks Associates Technologies, Inc. 40 * All rights reserved. 41 * 42 * This software was developed for the FreeBSD Project by Jonathan Lemon 43 * and NAI Labs, the Security Research Division of Network Associates, Inc. 44 * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the 45 * DARPA CHATS research program. 46 * 47 * Redistribution and use in source and binary forms, with or without 48 * modification, are permitted provided that the following conditions 49 * are met: 50 * 1. Redistributions of source code must retain the above copyright 51 * notice, this list of conditions and the following disclaimer. 52 * 2. Redistributions in binary form must reproduce the above copyright 53 * notice, this list of conditions and the following disclaimer in the 54 * documentation and/or other materials provided with the distribution. 55 * 3. The name of the author may not be used to endorse or promote 56 * products derived from this software without specific prior written 57 * permission. 58 * 59 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 60 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 61 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 62 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 63 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 64 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 65 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 66 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 67 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 68 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 69 * SUCH DAMAGE. 70 * 71 * $FreeBSD: src/sys/netinet/tcp_syncache.c,v 1.5.2.14 2003/02/24 04:02:27 silby Exp $ 72 */ 73 74 #include "opt_inet.h" 75 #include "opt_inet6.h" 76 #include "opt_ipsec.h" 77 78 #include <sys/param.h> 79 #include <sys/systm.h> 80 #include <sys/kernel.h> 81 #include <sys/sysctl.h> 82 #include <sys/malloc.h> 83 #include <sys/mbuf.h> 84 #include <sys/md5.h> 85 #include <sys/proc.h> /* for proc0 declaration */ 86 #include <sys/random.h> 87 #include <sys/socket.h> 88 #include <sys/socketvar.h> 89 #include <sys/in_cksum.h> 90 91 #include <sys/msgport2.h> 92 #include <net/netmsg2.h> 93 94 #include <net/if.h> 95 #include <net/route.h> 96 97 #include <netinet/in.h> 98 #include <netinet/in_systm.h> 99 #include <netinet/ip.h> 100 #include <netinet/in_var.h> 101 #include <netinet/in_pcb.h> 102 #include <netinet/ip_var.h> 103 #include <netinet/ip6.h> 104 #ifdef INET6 105 #include <netinet/icmp6.h> 106 #include <netinet6/nd6.h> 107 #endif 108 #include <netinet6/ip6_var.h> 109 #include <netinet6/in6_pcb.h> 110 #include <netinet/tcp.h> 111 #include <netinet/tcp_fsm.h> 112 #include <netinet/tcp_seq.h> 113 #include <netinet/tcp_timer.h> 114 #include <netinet/tcp_timer2.h> 115 #include <netinet/tcp_var.h> 116 #include <netinet6/tcp6_var.h> 117 118 #ifdef IPSEC 119 #include <netinet6/ipsec.h> 120 #ifdef INET6 121 #include <netinet6/ipsec6.h> 122 #endif 123 #include <netproto/key/key.h> 124 #endif /*IPSEC*/ 125 126 #ifdef FAST_IPSEC 127 #include <netproto/ipsec/ipsec.h> 128 #ifdef INET6 129 #include <netproto/ipsec/ipsec6.h> 130 #endif 131 #include <netproto/ipsec/key.h> 132 #define IPSEC 133 #endif /*FAST_IPSEC*/ 134 135 static int tcp_syncookies = 1; 136 SYSCTL_INT(_net_inet_tcp, OID_AUTO, syncookies, CTLFLAG_RW, 137 &tcp_syncookies, 0, 138 "Use TCP SYN cookies if the syncache overflows"); 139 140 static void syncache_drop(struct syncache *, struct syncache_head *); 141 static void syncache_free(struct syncache *); 142 static void syncache_insert(struct syncache *, struct syncache_head *); 143 struct syncache *syncache_lookup(struct in_conninfo *, struct syncache_head **); 144 static int syncache_respond(struct syncache *, struct mbuf *); 145 static struct socket *syncache_socket(struct syncache *, struct socket *, 146 struct mbuf *); 147 static void syncache_timer(void *); 148 static u_int32_t syncookie_generate(struct syncache *); 149 static struct syncache *syncookie_lookup(struct in_conninfo *, 150 struct tcphdr *, struct socket *); 151 152 /* 153 * Transmit the SYN,ACK fewer times than TCP_MAXRXTSHIFT specifies. 154 * 3 retransmits corresponds to a timeout of (1 + 2 + 4 + 8 == 15) seconds, 155 * the odds are that the user has given up attempting to connect by then. 156 */ 157 #define SYNCACHE_MAXREXMTS 3 158 159 /* Arbitrary values */ 160 #define TCP_SYNCACHE_HASHSIZE 512 161 #define TCP_SYNCACHE_BUCKETLIMIT 30 162 163 struct netmsg_sc_timer { 164 struct netmsg_base base; 165 struct msgrec *nm_mrec; /* back pointer to containing msgrec */ 166 }; 167 168 struct msgrec { 169 struct netmsg_sc_timer msg; 170 lwkt_port_t port; /* constant after init */ 171 int slot; /* constant after init */ 172 }; 173 174 static void syncache_timer_handler(netmsg_t); 175 176 struct tcp_syncache { 177 u_int hashsize; 178 u_int hashmask; 179 u_int bucket_limit; 180 u_int cache_limit; 181 u_int rexmt_limit; 182 u_int hash_secret; 183 }; 184 static struct tcp_syncache tcp_syncache; 185 186 TAILQ_HEAD(syncache_list, syncache); 187 188 struct tcp_syncache_percpu { 189 struct syncache_head *hashbase; 190 u_int cache_count; 191 struct syncache_list timerq[SYNCACHE_MAXREXMTS + 1]; 192 struct callout tt_timerq[SYNCACHE_MAXREXMTS + 1]; 193 struct msgrec mrec[SYNCACHE_MAXREXMTS + 1]; 194 }; 195 static struct tcp_syncache_percpu tcp_syncache_percpu[MAXCPU]; 196 197 static struct lwkt_port syncache_null_rport; 198 199 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, syncache, CTLFLAG_RW, 0, "TCP SYN cache"); 200 201 SYSCTL_INT(_net_inet_tcp_syncache, OID_AUTO, bucketlimit, CTLFLAG_RD, 202 &tcp_syncache.bucket_limit, 0, "Per-bucket hash limit for syncache"); 203 204 SYSCTL_INT(_net_inet_tcp_syncache, OID_AUTO, cachelimit, CTLFLAG_RD, 205 &tcp_syncache.cache_limit, 0, "Overall entry limit for syncache"); 206 207 /* XXX JH */ 208 #if 0 209 SYSCTL_INT(_net_inet_tcp_syncache, OID_AUTO, count, CTLFLAG_RD, 210 &tcp_syncache.cache_count, 0, "Current number of entries in syncache"); 211 #endif 212 213 SYSCTL_INT(_net_inet_tcp_syncache, OID_AUTO, hashsize, CTLFLAG_RD, 214 &tcp_syncache.hashsize, 0, "Size of TCP syncache hashtable"); 215 216 SYSCTL_INT(_net_inet_tcp_syncache, OID_AUTO, rexmtlimit, CTLFLAG_RW, 217 &tcp_syncache.rexmt_limit, 0, "Limit on SYN/ACK retransmissions"); 218 219 static MALLOC_DEFINE(M_SYNCACHE, "syncache", "TCP syncache"); 220 221 #define SYNCACHE_HASH(inc, mask) \ 222 ((tcp_syncache.hash_secret ^ \ 223 (inc)->inc_faddr.s_addr ^ \ 224 ((inc)->inc_faddr.s_addr >> 16) ^ \ 225 (inc)->inc_fport ^ (inc)->inc_lport) & mask) 226 227 #define SYNCACHE_HASH6(inc, mask) \ 228 ((tcp_syncache.hash_secret ^ \ 229 (inc)->inc6_faddr.s6_addr32[0] ^ \ 230 (inc)->inc6_faddr.s6_addr32[3] ^ \ 231 (inc)->inc_fport ^ (inc)->inc_lport) & mask) 232 233 #define ENDPTS_EQ(a, b) ( \ 234 (a)->ie_fport == (b)->ie_fport && \ 235 (a)->ie_lport == (b)->ie_lport && \ 236 (a)->ie_faddr.s_addr == (b)->ie_faddr.s_addr && \ 237 (a)->ie_laddr.s_addr == (b)->ie_laddr.s_addr \ 238 ) 239 240 #define ENDPTS6_EQ(a, b) (memcmp(a, b, sizeof(*a)) == 0) 241 242 static __inline void 243 syncache_timeout(struct tcp_syncache_percpu *syncache_percpu, 244 struct syncache *sc, int slot) 245 { 246 if (slot > 0) { 247 /* 248 * Record that SYN|ACK was lost. 249 * Needed by RFC3390 and RFC6298. 250 */ 251 sc->sc_flags |= SCF_SYN_WASLOST; 252 } 253 sc->sc_rxtslot = slot; 254 sc->sc_rxttime = ticks + TCPTV_RTOBASE * tcp_backoff[slot]; 255 TAILQ_INSERT_TAIL(&syncache_percpu->timerq[slot], sc, sc_timerq); 256 if (!callout_active(&syncache_percpu->tt_timerq[slot])) { 257 callout_reset(&syncache_percpu->tt_timerq[slot], 258 TCPTV_RTOBASE * tcp_backoff[slot], 259 syncache_timer, 260 &syncache_percpu->mrec[slot]); 261 } 262 } 263 264 static void 265 syncache_free(struct syncache *sc) 266 { 267 struct rtentry *rt; 268 #ifdef INET6 269 const boolean_t isipv6 = sc->sc_inc.inc_isipv6; 270 #else 271 const boolean_t isipv6 = FALSE; 272 #endif 273 274 if (sc->sc_ipopts) 275 m_free(sc->sc_ipopts); 276 277 rt = isipv6 ? sc->sc_route6.ro_rt : sc->sc_route.ro_rt; 278 if (rt != NULL) { 279 /* 280 * If this is the only reference to a protocol-cloned 281 * route, remove it immediately. 282 */ 283 if ((rt->rt_flags & RTF_WASCLONED) && rt->rt_refcnt == 1) 284 rtrequest(RTM_DELETE, rt_key(rt), rt->rt_gateway, 285 rt_mask(rt), rt->rt_flags, NULL); 286 RTFREE(rt); 287 } 288 kfree(sc, M_SYNCACHE); 289 } 290 291 void 292 syncache_init(void) 293 { 294 int i, cpu; 295 296 tcp_syncache.hashsize = TCP_SYNCACHE_HASHSIZE; 297 tcp_syncache.bucket_limit = TCP_SYNCACHE_BUCKETLIMIT; 298 tcp_syncache.cache_limit = 299 tcp_syncache.hashsize * tcp_syncache.bucket_limit; 300 tcp_syncache.rexmt_limit = SYNCACHE_MAXREXMTS; 301 tcp_syncache.hash_secret = karc4random(); 302 303 TUNABLE_INT_FETCH("net.inet.tcp.syncache.hashsize", 304 &tcp_syncache.hashsize); 305 TUNABLE_INT_FETCH("net.inet.tcp.syncache.cachelimit", 306 &tcp_syncache.cache_limit); 307 TUNABLE_INT_FETCH("net.inet.tcp.syncache.bucketlimit", 308 &tcp_syncache.bucket_limit); 309 if (!powerof2(tcp_syncache.hashsize)) { 310 kprintf("WARNING: syncache hash size is not a power of 2.\n"); 311 tcp_syncache.hashsize = 512; /* safe default */ 312 } 313 tcp_syncache.hashmask = tcp_syncache.hashsize - 1; 314 315 lwkt_initport_replyonly_null(&syncache_null_rport); 316 317 for (cpu = 0; cpu < ncpus2; cpu++) { 318 struct tcp_syncache_percpu *syncache_percpu; 319 320 syncache_percpu = &tcp_syncache_percpu[cpu]; 321 /* Allocate the hash table. */ 322 syncache_percpu->hashbase = kmalloc(tcp_syncache.hashsize * sizeof(struct syncache_head), 323 M_SYNCACHE, M_WAITOK); 324 325 /* Initialize the hash buckets. */ 326 for (i = 0; i < tcp_syncache.hashsize; i++) { 327 struct syncache_head *bucket; 328 329 bucket = &syncache_percpu->hashbase[i]; 330 TAILQ_INIT(&bucket->sch_bucket); 331 bucket->sch_length = 0; 332 } 333 334 for (i = 0; i <= SYNCACHE_MAXREXMTS; i++) { 335 /* Initialize the timer queues. */ 336 TAILQ_INIT(&syncache_percpu->timerq[i]); 337 callout_init_mp(&syncache_percpu->tt_timerq[i]); 338 339 syncache_percpu->mrec[i].slot = i; 340 syncache_percpu->mrec[i].port = cpu_portfn(cpu); 341 syncache_percpu->mrec[i].msg.nm_mrec = 342 &syncache_percpu->mrec[i]; 343 netmsg_init(&syncache_percpu->mrec[i].msg.base, 344 NULL, &syncache_null_rport, 345 0, syncache_timer_handler); 346 } 347 } 348 } 349 350 static void 351 syncache_insert(struct syncache *sc, struct syncache_head *sch) 352 { 353 struct tcp_syncache_percpu *syncache_percpu; 354 struct syncache *sc2; 355 int i; 356 357 syncache_percpu = &tcp_syncache_percpu[mycpu->gd_cpuid]; 358 359 /* 360 * Make sure that we don't overflow the per-bucket 361 * limit or the total cache size limit. 362 */ 363 if (sch->sch_length >= tcp_syncache.bucket_limit) { 364 /* 365 * The bucket is full, toss the oldest element. 366 */ 367 sc2 = TAILQ_FIRST(&sch->sch_bucket); 368 sc2->sc_tp->ts_recent = ticks; 369 syncache_drop(sc2, sch); 370 tcpstat.tcps_sc_bucketoverflow++; 371 } else if (syncache_percpu->cache_count >= tcp_syncache.cache_limit) { 372 /* 373 * The cache is full. Toss the oldest entry in the 374 * entire cache. This is the front entry in the 375 * first non-empty timer queue with the largest 376 * timeout value. 377 */ 378 for (i = SYNCACHE_MAXREXMTS; i >= 0; i--) { 379 sc2 = TAILQ_FIRST(&syncache_percpu->timerq[i]); 380 while (sc2 && (sc2->sc_flags & SCF_MARKER)) 381 sc2 = TAILQ_NEXT(sc2, sc_timerq); 382 if (sc2 != NULL) 383 break; 384 } 385 sc2->sc_tp->ts_recent = ticks; 386 syncache_drop(sc2, NULL); 387 tcpstat.tcps_sc_cacheoverflow++; 388 } 389 390 /* Initialize the entry's timer. */ 391 syncache_timeout(syncache_percpu, sc, 0); 392 393 /* Put it into the bucket. */ 394 TAILQ_INSERT_TAIL(&sch->sch_bucket, sc, sc_hash); 395 sch->sch_length++; 396 syncache_percpu->cache_count++; 397 tcpstat.tcps_sc_added++; 398 } 399 400 void 401 syncache_destroy(struct tcpcb *tp) 402 { 403 struct tcp_syncache_percpu *syncache_percpu; 404 struct syncache_head *bucket; 405 struct syncache *sc; 406 int i; 407 408 syncache_percpu = &tcp_syncache_percpu[mycpu->gd_cpuid]; 409 sc = NULL; 410 411 for (i = 0; i < tcp_syncache.hashsize; i++) { 412 bucket = &syncache_percpu->hashbase[i]; 413 TAILQ_FOREACH(sc, &bucket->sch_bucket, sc_hash) { 414 if (sc->sc_tp == tp) 415 sc->sc_tp = NULL; 416 } 417 } 418 } 419 420 static void 421 syncache_drop(struct syncache *sc, struct syncache_head *sch) 422 { 423 struct tcp_syncache_percpu *syncache_percpu; 424 #ifdef INET6 425 const boolean_t isipv6 = sc->sc_inc.inc_isipv6; 426 #else 427 const boolean_t isipv6 = FALSE; 428 #endif 429 430 syncache_percpu = &tcp_syncache_percpu[mycpu->gd_cpuid]; 431 432 if (sch == NULL) { 433 if (isipv6) { 434 sch = &syncache_percpu->hashbase[ 435 SYNCACHE_HASH6(&sc->sc_inc, tcp_syncache.hashmask)]; 436 } else { 437 sch = &syncache_percpu->hashbase[ 438 SYNCACHE_HASH(&sc->sc_inc, tcp_syncache.hashmask)]; 439 } 440 } 441 442 TAILQ_REMOVE(&sch->sch_bucket, sc, sc_hash); 443 sch->sch_length--; 444 syncache_percpu->cache_count--; 445 446 /* 447 * Cleanup 448 */ 449 if (sc->sc_tp) 450 sc->sc_tp = NULL; 451 452 /* 453 * Remove the entry from the syncache timer/timeout queue. Note 454 * that we do not try to stop any running timer since we do not know 455 * whether the timer's message is in-transit or not. Since timeouts 456 * are fairly long, taking an unneeded callout does not detrimentally 457 * effect performance. 458 */ 459 TAILQ_REMOVE(&syncache_percpu->timerq[sc->sc_rxtslot], sc, sc_timerq); 460 461 syncache_free(sc); 462 } 463 464 /* 465 * Place a timeout message on the TCP thread's message queue. 466 * This routine runs in soft interrupt context. 467 * 468 * An invariant is for this routine to be called, the callout must 469 * have been active. Note that the callout is not deactivated until 470 * after the message has been processed in syncache_timer_handler() below. 471 */ 472 static void 473 syncache_timer(void *p) 474 { 475 struct netmsg_sc_timer *msg = p; 476 477 lwkt_sendmsg(msg->nm_mrec->port, &msg->base.lmsg); 478 } 479 480 /* 481 * Service a timer message queued by timer expiration. 482 * This routine runs in the TCP protocol thread. 483 * 484 * Walk the timer queues, looking for SYN,ACKs that need to be retransmitted. 485 * If we have retransmitted an entry the maximum number of times, expire it. 486 * 487 * When we finish processing timed-out entries, we restart the timer if there 488 * are any entries still on the queue and deactivate it otherwise. Only after 489 * a timer has been deactivated here can it be restarted by syncache_timeout(). 490 */ 491 static void 492 syncache_timer_handler(netmsg_t msg) 493 { 494 struct tcp_syncache_percpu *syncache_percpu; 495 struct syncache *sc; 496 struct syncache marker; 497 struct syncache_list *list; 498 struct inpcb *inp; 499 int slot; 500 501 slot = ((struct netmsg_sc_timer *)msg)->nm_mrec->slot; 502 syncache_percpu = &tcp_syncache_percpu[mycpu->gd_cpuid]; 503 504 list = &syncache_percpu->timerq[slot]; 505 506 /* 507 * Use a marker to keep our place in the scan. syncache_drop() 508 * can block and cause any next pointer we cache to become stale. 509 */ 510 marker.sc_flags = SCF_MARKER; 511 TAILQ_INSERT_HEAD(list, &marker, sc_timerq); 512 513 while ((sc = TAILQ_NEXT(&marker, sc_timerq)) != NULL) { 514 /* 515 * Move the marker. 516 */ 517 TAILQ_REMOVE(list, &marker, sc_timerq); 518 TAILQ_INSERT_AFTER(list, sc, &marker, sc_timerq); 519 520 if (sc->sc_flags & SCF_MARKER) 521 continue; 522 523 if (ticks < sc->sc_rxttime) 524 break; /* finished because timerq sorted by time */ 525 if (sc->sc_tp == NULL) { 526 syncache_drop(sc, NULL); 527 tcpstat.tcps_sc_stale++; 528 continue; 529 } 530 inp = sc->sc_tp->t_inpcb; 531 if (slot == SYNCACHE_MAXREXMTS || 532 slot >= tcp_syncache.rexmt_limit || 533 inp == NULL || 534 inp->inp_gencnt != sc->sc_inp_gencnt) { 535 syncache_drop(sc, NULL); 536 tcpstat.tcps_sc_stale++; 537 continue; 538 } 539 /* 540 * syncache_respond() may call back into the syncache to 541 * to modify another entry, so do not obtain the next 542 * entry on the timer chain until it has completed. 543 */ 544 syncache_respond(sc, NULL); 545 tcpstat.tcps_sc_retransmitted++; 546 TAILQ_REMOVE(list, sc, sc_timerq); 547 syncache_timeout(syncache_percpu, sc, slot + 1); 548 } 549 TAILQ_REMOVE(list, &marker, sc_timerq); 550 551 if (sc != NULL) { 552 callout_reset(&syncache_percpu->tt_timerq[slot], 553 sc->sc_rxttime - ticks, syncache_timer, 554 &syncache_percpu->mrec[slot]); 555 } else { 556 callout_deactivate(&syncache_percpu->tt_timerq[slot]); 557 } 558 lwkt_replymsg(&msg->base.lmsg, 0); 559 } 560 561 /* 562 * Find an entry in the syncache. 563 */ 564 struct syncache * 565 syncache_lookup(struct in_conninfo *inc, struct syncache_head **schp) 566 { 567 struct tcp_syncache_percpu *syncache_percpu; 568 struct syncache *sc; 569 struct syncache_head *sch; 570 571 syncache_percpu = &tcp_syncache_percpu[mycpu->gd_cpuid]; 572 #ifdef INET6 573 if (inc->inc_isipv6) { 574 sch = &syncache_percpu->hashbase[ 575 SYNCACHE_HASH6(inc, tcp_syncache.hashmask)]; 576 *schp = sch; 577 TAILQ_FOREACH(sc, &sch->sch_bucket, sc_hash) 578 if (ENDPTS6_EQ(&inc->inc_ie, &sc->sc_inc.inc_ie)) 579 return (sc); 580 } else 581 #endif 582 { 583 sch = &syncache_percpu->hashbase[ 584 SYNCACHE_HASH(inc, tcp_syncache.hashmask)]; 585 *schp = sch; 586 TAILQ_FOREACH(sc, &sch->sch_bucket, sc_hash) { 587 #ifdef INET6 588 if (sc->sc_inc.inc_isipv6) 589 continue; 590 #endif 591 if (ENDPTS_EQ(&inc->inc_ie, &sc->sc_inc.inc_ie)) 592 return (sc); 593 } 594 } 595 return (NULL); 596 } 597 598 /* 599 * This function is called when we get a RST for a 600 * non-existent connection, so that we can see if the 601 * connection is in the syn cache. If it is, zap it. 602 */ 603 void 604 syncache_chkrst(struct in_conninfo *inc, struct tcphdr *th) 605 { 606 struct syncache *sc; 607 struct syncache_head *sch; 608 609 sc = syncache_lookup(inc, &sch); 610 if (sc == NULL) { 611 return; 612 } 613 /* 614 * If the RST bit is set, check the sequence number to see 615 * if this is a valid reset segment. 616 * RFC 793 page 37: 617 * In all states except SYN-SENT, all reset (RST) segments 618 * are validated by checking their SEQ-fields. A reset is 619 * valid if its sequence number is in the window. 620 * 621 * The sequence number in the reset segment is normally an 622 * echo of our outgoing acknowlegement numbers, but some hosts 623 * send a reset with the sequence number at the rightmost edge 624 * of our receive window, and we have to handle this case. 625 */ 626 if (SEQ_GEQ(th->th_seq, sc->sc_irs) && 627 SEQ_LEQ(th->th_seq, sc->sc_irs + sc->sc_wnd)) { 628 syncache_drop(sc, sch); 629 tcpstat.tcps_sc_reset++; 630 } 631 } 632 633 void 634 syncache_badack(struct in_conninfo *inc) 635 { 636 struct syncache *sc; 637 struct syncache_head *sch; 638 639 sc = syncache_lookup(inc, &sch); 640 if (sc != NULL) { 641 syncache_drop(sc, sch); 642 tcpstat.tcps_sc_badack++; 643 } 644 } 645 646 void 647 syncache_unreach(struct in_conninfo *inc, struct tcphdr *th) 648 { 649 struct syncache *sc; 650 struct syncache_head *sch; 651 652 /* we are called at splnet() here */ 653 sc = syncache_lookup(inc, &sch); 654 if (sc == NULL) 655 return; 656 657 /* If the sequence number != sc_iss, then it's a bogus ICMP msg */ 658 if (ntohl(th->th_seq) != sc->sc_iss) 659 return; 660 661 /* 662 * If we've rertransmitted 3 times and this is our second error, 663 * we remove the entry. Otherwise, we allow it to continue on. 664 * This prevents us from incorrectly nuking an entry during a 665 * spurious network outage. 666 * 667 * See tcp_notify(). 668 */ 669 if ((sc->sc_flags & SCF_UNREACH) == 0 || sc->sc_rxtslot < 3) { 670 sc->sc_flags |= SCF_UNREACH; 671 return; 672 } 673 syncache_drop(sc, sch); 674 tcpstat.tcps_sc_unreach++; 675 } 676 677 /* 678 * Build a new TCP socket structure from a syncache entry. 679 * 680 * This is called from the context of the SYN+ACK 681 */ 682 static struct socket * 683 syncache_socket(struct syncache *sc, struct socket *lso, struct mbuf *m) 684 { 685 struct inpcb *inp = NULL, *linp; 686 struct socket *so; 687 struct tcpcb *tp, *ltp; 688 lwkt_port_t port; 689 #ifdef INET6 690 const boolean_t isipv6 = sc->sc_inc.inc_isipv6; 691 #else 692 const boolean_t isipv6 = FALSE; 693 #endif 694 struct sockaddr_in sin_faddr; 695 struct sockaddr_in6 sin6_faddr; 696 struct sockaddr *faddr; 697 698 if (isipv6) { 699 faddr = (struct sockaddr *)&sin6_faddr; 700 sin6_faddr.sin6_family = AF_INET6; 701 sin6_faddr.sin6_len = sizeof(sin6_faddr); 702 sin6_faddr.sin6_addr = sc->sc_inc.inc6_faddr; 703 sin6_faddr.sin6_port = sc->sc_inc.inc_fport; 704 sin6_faddr.sin6_flowinfo = sin6_faddr.sin6_scope_id = 0; 705 } else { 706 faddr = (struct sockaddr *)&sin_faddr; 707 sin_faddr.sin_family = AF_INET; 708 sin_faddr.sin_len = sizeof(sin_faddr); 709 sin_faddr.sin_addr = sc->sc_inc.inc_faddr; 710 sin_faddr.sin_port = sc->sc_inc.inc_fport; 711 bzero(sin_faddr.sin_zero, sizeof(sin_faddr.sin_zero)); 712 } 713 714 /* 715 * Ok, create the full blown connection, and set things up 716 * as they would have been set up if we had created the 717 * connection when the SYN arrived. If we can't create 718 * the connection, abort it. 719 * 720 * Set the protocol processing port for the socket to the current 721 * port (that the connection came in on). 722 */ 723 so = sonewconn_faddr(lso, SS_ISCONNECTED, faddr); 724 if (so == NULL) { 725 /* 726 * Drop the connection; we will send a RST if the peer 727 * retransmits the ACK, 728 */ 729 tcpstat.tcps_listendrop++; 730 goto abort; 731 } 732 733 /* 734 * Insert new socket into hash list. 735 */ 736 inp = so->so_pcb; 737 inp->inp_inc.inc_isipv6 = sc->sc_inc.inc_isipv6; 738 if (isipv6) { 739 inp->in6p_laddr = sc->sc_inc.inc6_laddr; 740 } else { 741 #ifdef INET6 742 inp->inp_vflag &= ~INP_IPV6; 743 inp->inp_vflag |= INP_IPV4; 744 inp->inp_flags &= ~IN6P_IPV6_V6ONLY; 745 #endif 746 inp->inp_laddr = sc->sc_inc.inc_laddr; 747 } 748 inp->inp_lport = sc->sc_inc.inc_lport; 749 if (in_pcbinsporthash(inp) != 0) { 750 /* 751 * Undo the assignments above if we failed to 752 * put the PCB on the hash lists. 753 */ 754 if (isipv6) 755 inp->in6p_laddr = kin6addr_any; 756 else 757 inp->inp_laddr.s_addr = INADDR_ANY; 758 inp->inp_lport = 0; 759 goto abort; 760 } 761 linp = lso->so_pcb; 762 #ifdef IPSEC 763 /* copy old policy into new socket's */ 764 if (ipsec_copy_policy(linp->inp_sp, inp->inp_sp)) 765 kprintf("syncache_expand: could not copy policy\n"); 766 #endif 767 if (isipv6) { 768 struct in6_addr laddr6; 769 /* 770 * Inherit socket options from the listening socket. 771 * Note that in6p_inputopts are not (and should not be) 772 * copied, since it stores previously received options and is 773 * used to detect if each new option is different than the 774 * previous one and hence should be passed to a user. 775 * If we copied in6p_inputopts, a user would not be able to 776 * receive options just after calling the accept system call. 777 */ 778 inp->inp_flags |= linp->inp_flags & INP_CONTROLOPTS; 779 if (linp->in6p_outputopts) 780 inp->in6p_outputopts = 781 ip6_copypktopts(linp->in6p_outputopts, M_INTWAIT); 782 inp->in6p_route = sc->sc_route6; 783 sc->sc_route6.ro_rt = NULL; 784 785 laddr6 = inp->in6p_laddr; 786 if (IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_laddr)) 787 inp->in6p_laddr = sc->sc_inc.inc6_laddr; 788 if (in6_pcbconnect(inp, faddr, &thread0)) { 789 inp->in6p_laddr = laddr6; 790 goto abort; 791 } 792 } else { 793 struct in_addr laddr; 794 795 inp->inp_options = ip_srcroute(m); 796 if (inp->inp_options == NULL) { 797 inp->inp_options = sc->sc_ipopts; 798 sc->sc_ipopts = NULL; 799 } 800 inp->inp_route = sc->sc_route; 801 sc->sc_route.ro_rt = NULL; 802 803 laddr = inp->inp_laddr; 804 if (inp->inp_laddr.s_addr == INADDR_ANY) 805 inp->inp_laddr = sc->sc_inc.inc_laddr; 806 if (in_pcbconnect(inp, faddr, &thread0)) { 807 inp->inp_laddr = laddr; 808 goto abort; 809 } 810 } 811 812 /* 813 * The current port should be in the context of the SYN+ACK and 814 * so should match the tcp address port. 815 * 816 * XXX we may be running on the netisr thread instead of a tcp 817 * thread, in which case port will not match 818 * curthread->td_msgport. 819 */ 820 if (isipv6) { 821 port = tcp6_addrport(); 822 } else { 823 port = tcp_addrport(inp->inp_faddr.s_addr, inp->inp_fport, 824 inp->inp_laddr.s_addr, inp->inp_lport); 825 } 826 if (port != &curthread->td_msgport) { 827 print_backtrace(-1); 828 kprintf("TCP PORT MISMATCH %p vs %p\n", 829 port, &curthread->td_msgport); 830 } 831 /*KKASSERT(port == &curthread->td_msgport);*/ 832 833 tp = intotcpcb(inp); 834 tp->t_state = TCPS_SYN_RECEIVED; 835 tp->iss = sc->sc_iss; 836 tp->irs = sc->sc_irs; 837 tcp_rcvseqinit(tp); 838 tcp_sendseqinit(tp); 839 tp->snd_wl1 = sc->sc_irs; 840 tp->rcv_up = sc->sc_irs + 1; 841 tp->rcv_wnd = sc->sc_wnd; 842 tp->rcv_adv += tp->rcv_wnd; 843 844 tp->t_flags = sototcpcb(lso)->t_flags & (TF_NOPUSH | TF_NODELAY); 845 if (sc->sc_flags & SCF_NOOPT) 846 tp->t_flags |= TF_NOOPT; 847 if (sc->sc_flags & SCF_WINSCALE) { 848 tp->t_flags |= TF_REQ_SCALE | TF_RCVD_SCALE; 849 tp->requested_s_scale = sc->sc_requested_s_scale; 850 tp->request_r_scale = sc->sc_request_r_scale; 851 } 852 if (sc->sc_flags & SCF_TIMESTAMP) { 853 tp->t_flags |= TF_REQ_TSTMP | TF_RCVD_TSTMP; 854 tp->ts_recent = sc->sc_tsrecent; 855 tp->ts_recent_age = ticks; 856 } 857 if (sc->sc_flags & SCF_SACK_PERMITTED) 858 tp->t_flags |= TF_SACK_PERMITTED; 859 if (sc->sc_flags & SCF_SYN_WASLOST) 860 tp->t_flags |= TF_SYN_WASLOST; 861 862 #ifdef TCP_SIGNATURE 863 if (sc->sc_flags & SCF_SIGNATURE) 864 tp->t_flags |= TF_SIGNATURE; 865 #endif /* TCP_SIGNATURE */ 866 867 tcp_mss(tp, sc->sc_peer_mss); 868 869 /* 870 * Inherit some properties from the listen socket 871 */ 872 ltp = intotcpcb(linp); 873 tp->t_keepinit = ltp->t_keepinit; 874 tp->t_keepidle = ltp->t_keepidle; 875 tp->t_keepintvl = ltp->t_keepintvl; 876 tp->t_keepcnt = ltp->t_keepcnt; 877 tp->t_maxidle = ltp->t_maxidle; 878 879 tcp_create_timermsg(tp, port); 880 tcp_callout_reset(tp, tp->tt_keep, tp->t_keepinit, tcp_timer_keep); 881 882 tcpstat.tcps_accepts++; 883 return (so); 884 885 abort: 886 if (so != NULL) 887 soabort_oncpu(so); 888 return (NULL); 889 } 890 891 /* 892 * This function gets called when we receive an ACK for a 893 * socket in the LISTEN state. We look up the connection 894 * in the syncache, and if its there, we pull it out of 895 * the cache and turn it into a full-blown connection in 896 * the SYN-RECEIVED state. 897 */ 898 int 899 syncache_expand(struct in_conninfo *inc, struct tcphdr *th, struct socket **sop, 900 struct mbuf *m) 901 { 902 struct syncache *sc; 903 struct syncache_head *sch; 904 struct socket *so; 905 906 sc = syncache_lookup(inc, &sch); 907 if (sc == NULL) { 908 /* 909 * There is no syncache entry, so see if this ACK is 910 * a returning syncookie. To do this, first: 911 * A. See if this socket has had a syncache entry dropped in 912 * the past. We don't want to accept a bogus syncookie 913 * if we've never received a SYN. 914 * B. check that the syncookie is valid. If it is, then 915 * cobble up a fake syncache entry, and return. 916 */ 917 if (!tcp_syncookies) 918 return (0); 919 sc = syncookie_lookup(inc, th, *sop); 920 if (sc == NULL) 921 return (0); 922 sch = NULL; 923 tcpstat.tcps_sc_recvcookie++; 924 } 925 926 /* 927 * If seg contains an ACK, but not for our SYN/ACK, send a RST. 928 */ 929 if (th->th_ack != sc->sc_iss + 1) 930 return (0); 931 932 so = syncache_socket(sc, *sop, m); 933 if (so == NULL) { 934 #if 0 935 resetandabort: 936 /* XXXjlemon check this - is this correct? */ 937 tcp_respond(NULL, m, m, th, 938 th->th_seq + tlen, (tcp_seq)0, TH_RST | TH_ACK); 939 #endif 940 m_freem(m); /* XXX only needed for above */ 941 tcpstat.tcps_sc_aborted++; 942 } else { 943 tcpstat.tcps_sc_completed++; 944 } 945 if (sch == NULL) 946 syncache_free(sc); 947 else 948 syncache_drop(sc, sch); 949 *sop = so; 950 return (1); 951 } 952 953 /* 954 * Given a LISTEN socket and an inbound SYN request, add 955 * this to the syn cache, and send back a segment: 956 * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK> 957 * to the source. 958 * 959 * IMPORTANT NOTE: We do _NOT_ ACK data that might accompany the SYN. 960 * Doing so would require that we hold onto the data and deliver it 961 * to the application. However, if we are the target of a SYN-flood 962 * DoS attack, an attacker could send data which would eventually 963 * consume all available buffer space if it were ACKed. By not ACKing 964 * the data, we avoid this DoS scenario. 965 */ 966 int 967 syncache_add(struct in_conninfo *inc, struct tcpopt *to, struct tcphdr *th, 968 struct socket *so, struct mbuf *m) 969 { 970 struct tcp_syncache_percpu *syncache_percpu; 971 struct tcpcb *tp; 972 struct syncache *sc = NULL; 973 struct syncache_head *sch; 974 struct mbuf *ipopts = NULL; 975 int win; 976 977 syncache_percpu = &tcp_syncache_percpu[mycpu->gd_cpuid]; 978 tp = sototcpcb(so); 979 980 /* 981 * Remember the IP options, if any. 982 */ 983 #ifdef INET6 984 if (!inc->inc_isipv6) 985 #endif 986 ipopts = ip_srcroute(m); 987 988 /* 989 * See if we already have an entry for this connection. 990 * If we do, resend the SYN,ACK, and reset the retransmit timer. 991 * 992 * XXX 993 * The syncache should be re-initialized with the contents 994 * of the new SYN which may have different options. 995 */ 996 sc = syncache_lookup(inc, &sch); 997 if (sc != NULL) { 998 tcpstat.tcps_sc_dupsyn++; 999 if (ipopts) { 1000 /* 1001 * If we were remembering a previous source route, 1002 * forget it and use the new one we've been given. 1003 */ 1004 if (sc->sc_ipopts) 1005 m_free(sc->sc_ipopts); 1006 sc->sc_ipopts = ipopts; 1007 } 1008 /* 1009 * Update timestamp if present. 1010 */ 1011 if (sc->sc_flags & SCF_TIMESTAMP) 1012 sc->sc_tsrecent = to->to_tsval; 1013 1014 /* Just update the TOF_SACK_PERMITTED for now. */ 1015 if (tcp_do_sack && (to->to_flags & TOF_SACK_PERMITTED)) 1016 sc->sc_flags |= SCF_SACK_PERMITTED; 1017 else 1018 sc->sc_flags &= ~SCF_SACK_PERMITTED; 1019 1020 /* 1021 * PCB may have changed, pick up new values. 1022 */ 1023 sc->sc_tp = tp; 1024 sc->sc_inp_gencnt = tp->t_inpcb->inp_gencnt; 1025 if (syncache_respond(sc, m) == 0) { 1026 TAILQ_REMOVE(&syncache_percpu->timerq[sc->sc_rxtslot], 1027 sc, sc_timerq); 1028 syncache_timeout(syncache_percpu, sc, sc->sc_rxtslot); 1029 tcpstat.tcps_sndacks++; 1030 tcpstat.tcps_sndtotal++; 1031 } 1032 return (1); 1033 } 1034 1035 /* 1036 * Fill in the syncache values. 1037 */ 1038 sc = kmalloc(sizeof(struct syncache), M_SYNCACHE, M_WAITOK|M_ZERO); 1039 sc->sc_inp_gencnt = tp->t_inpcb->inp_gencnt; 1040 sc->sc_ipopts = ipopts; 1041 sc->sc_inc.inc_fport = inc->inc_fport; 1042 sc->sc_inc.inc_lport = inc->inc_lport; 1043 sc->sc_tp = tp; 1044 #ifdef INET6 1045 sc->sc_inc.inc_isipv6 = inc->inc_isipv6; 1046 if (inc->inc_isipv6) { 1047 sc->sc_inc.inc6_faddr = inc->inc6_faddr; 1048 sc->sc_inc.inc6_laddr = inc->inc6_laddr; 1049 sc->sc_route6.ro_rt = NULL; 1050 } else 1051 #endif 1052 { 1053 sc->sc_inc.inc_faddr = inc->inc_faddr; 1054 sc->sc_inc.inc_laddr = inc->inc_laddr; 1055 sc->sc_route.ro_rt = NULL; 1056 } 1057 sc->sc_irs = th->th_seq; 1058 sc->sc_flags = 0; 1059 sc->sc_peer_mss = to->to_flags & TOF_MSS ? to->to_mss : 0; 1060 if (tcp_syncookies) 1061 sc->sc_iss = syncookie_generate(sc); 1062 else 1063 sc->sc_iss = karc4random(); 1064 1065 /* Initial receive window: clip ssb_space to [0 .. TCP_MAXWIN] */ 1066 win = ssb_space(&so->so_rcv); 1067 win = imax(win, 0); 1068 win = imin(win, TCP_MAXWIN); 1069 sc->sc_wnd = win; 1070 1071 if (tcp_do_rfc1323) { 1072 /* 1073 * A timestamp received in a SYN makes 1074 * it ok to send timestamp requests and replies. 1075 */ 1076 if (to->to_flags & TOF_TS) { 1077 sc->sc_tsrecent = to->to_tsval; 1078 sc->sc_flags |= SCF_TIMESTAMP; 1079 } 1080 if (to->to_flags & TOF_SCALE) { 1081 int wscale = TCP_MIN_WINSHIFT; 1082 1083 /* Compute proper scaling value from buffer space */ 1084 while (wscale < TCP_MAX_WINSHIFT && 1085 (TCP_MAXWIN << wscale) < so->so_rcv.ssb_hiwat) { 1086 wscale++; 1087 } 1088 sc->sc_request_r_scale = wscale; 1089 sc->sc_requested_s_scale = to->to_requested_s_scale; 1090 sc->sc_flags |= SCF_WINSCALE; 1091 } 1092 } 1093 if (tcp_do_sack && (to->to_flags & TOF_SACK_PERMITTED)) 1094 sc->sc_flags |= SCF_SACK_PERMITTED; 1095 if (tp->t_flags & TF_NOOPT) 1096 sc->sc_flags = SCF_NOOPT; 1097 #ifdef TCP_SIGNATURE 1098 /* 1099 * If listening socket requested TCP digests, and received SYN 1100 * contains the option, flag this in the syncache so that 1101 * syncache_respond() will do the right thing with the SYN+ACK. 1102 * XXX Currently we always record the option by default and will 1103 * attempt to use it in syncache_respond(). 1104 */ 1105 if (to->to_flags & TOF_SIGNATURE) 1106 sc->sc_flags = SCF_SIGNATURE; 1107 #endif /* TCP_SIGNATURE */ 1108 1109 if (syncache_respond(sc, m) == 0) { 1110 syncache_insert(sc, sch); 1111 tcpstat.tcps_sndacks++; 1112 tcpstat.tcps_sndtotal++; 1113 } else { 1114 syncache_free(sc); 1115 tcpstat.tcps_sc_dropped++; 1116 } 1117 return (1); 1118 } 1119 1120 static int 1121 syncache_respond(struct syncache *sc, struct mbuf *m) 1122 { 1123 u_int8_t *optp; 1124 int optlen, error; 1125 u_int16_t tlen, hlen, mssopt; 1126 struct ip *ip = NULL; 1127 struct rtentry *rt; 1128 struct tcphdr *th; 1129 struct ip6_hdr *ip6 = NULL; 1130 #ifdef INET6 1131 const boolean_t isipv6 = sc->sc_inc.inc_isipv6; 1132 #else 1133 const boolean_t isipv6 = FALSE; 1134 #endif 1135 1136 if (isipv6) { 1137 rt = tcp_rtlookup6(&sc->sc_inc); 1138 if (rt != NULL) 1139 mssopt = rt->rt_ifp->if_mtu - 1140 (sizeof(struct ip6_hdr) + sizeof(struct tcphdr)); 1141 else 1142 mssopt = tcp_v6mssdflt; 1143 hlen = sizeof(struct ip6_hdr); 1144 } else { 1145 rt = tcp_rtlookup(&sc->sc_inc); 1146 if (rt != NULL) 1147 mssopt = rt->rt_ifp->if_mtu - 1148 (sizeof(struct ip) + sizeof(struct tcphdr)); 1149 else 1150 mssopt = tcp_mssdflt; 1151 hlen = sizeof(struct ip); 1152 } 1153 1154 /* Compute the size of the TCP options. */ 1155 if (sc->sc_flags & SCF_NOOPT) { 1156 optlen = 0; 1157 } else { 1158 optlen = TCPOLEN_MAXSEG + 1159 ((sc->sc_flags & SCF_WINSCALE) ? 4 : 0) + 1160 ((sc->sc_flags & SCF_TIMESTAMP) ? TCPOLEN_TSTAMP_APPA : 0) + 1161 ((sc->sc_flags & SCF_SACK_PERMITTED) ? 1162 TCPOLEN_SACK_PERMITTED_ALIGNED : 0); 1163 #ifdef TCP_SIGNATURE 1164 optlen += ((sc->sc_flags & SCF_SIGNATURE) ? 1165 (TCPOLEN_SIGNATURE + 2) : 0); 1166 #endif /* TCP_SIGNATURE */ 1167 } 1168 tlen = hlen + sizeof(struct tcphdr) + optlen; 1169 1170 /* 1171 * XXX 1172 * assume that the entire packet will fit in a header mbuf 1173 */ 1174 KASSERT(max_linkhdr + tlen <= MHLEN, ("syncache: mbuf too small")); 1175 1176 /* 1177 * XXX shouldn't this reuse the mbuf if possible ? 1178 * Create the IP+TCP header from scratch. 1179 */ 1180 if (m) 1181 m_freem(m); 1182 1183 m = m_gethdr(MB_DONTWAIT, MT_HEADER); 1184 if (m == NULL) 1185 return (ENOBUFS); 1186 m->m_data += max_linkhdr; 1187 m->m_len = tlen; 1188 m->m_pkthdr.len = tlen; 1189 m->m_pkthdr.rcvif = NULL; 1190 1191 if (isipv6) { 1192 ip6 = mtod(m, struct ip6_hdr *); 1193 ip6->ip6_vfc = IPV6_VERSION; 1194 ip6->ip6_nxt = IPPROTO_TCP; 1195 ip6->ip6_src = sc->sc_inc.inc6_laddr; 1196 ip6->ip6_dst = sc->sc_inc.inc6_faddr; 1197 ip6->ip6_plen = htons(tlen - hlen); 1198 /* ip6_hlim is set after checksum */ 1199 /* ip6_flow = ??? */ 1200 1201 th = (struct tcphdr *)(ip6 + 1); 1202 } else { 1203 ip = mtod(m, struct ip *); 1204 ip->ip_v = IPVERSION; 1205 ip->ip_hl = sizeof(struct ip) >> 2; 1206 ip->ip_len = tlen; 1207 ip->ip_id = 0; 1208 ip->ip_off = 0; 1209 ip->ip_sum = 0; 1210 ip->ip_p = IPPROTO_TCP; 1211 ip->ip_src = sc->sc_inc.inc_laddr; 1212 ip->ip_dst = sc->sc_inc.inc_faddr; 1213 ip->ip_ttl = sc->sc_tp->t_inpcb->inp_ip_ttl; /* XXX */ 1214 ip->ip_tos = sc->sc_tp->t_inpcb->inp_ip_tos; /* XXX */ 1215 1216 /* 1217 * See if we should do MTU discovery. Route lookups are 1218 * expensive, so we will only unset the DF bit if: 1219 * 1220 * 1) path_mtu_discovery is disabled 1221 * 2) the SCF_UNREACH flag has been set 1222 */ 1223 if (path_mtu_discovery 1224 && ((sc->sc_flags & SCF_UNREACH) == 0)) { 1225 ip->ip_off |= IP_DF; 1226 } 1227 1228 th = (struct tcphdr *)(ip + 1); 1229 } 1230 th->th_sport = sc->sc_inc.inc_lport; 1231 th->th_dport = sc->sc_inc.inc_fport; 1232 1233 th->th_seq = htonl(sc->sc_iss); 1234 th->th_ack = htonl(sc->sc_irs + 1); 1235 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 1236 th->th_x2 = 0; 1237 th->th_flags = TH_SYN | TH_ACK; 1238 th->th_win = htons(sc->sc_wnd); 1239 th->th_urp = 0; 1240 1241 /* Tack on the TCP options. */ 1242 if (optlen == 0) 1243 goto no_options; 1244 optp = (u_int8_t *)(th + 1); 1245 *optp++ = TCPOPT_MAXSEG; 1246 *optp++ = TCPOLEN_MAXSEG; 1247 *optp++ = (mssopt >> 8) & 0xff; 1248 *optp++ = mssopt & 0xff; 1249 1250 if (sc->sc_flags & SCF_WINSCALE) { 1251 *((u_int32_t *)optp) = htonl(TCPOPT_NOP << 24 | 1252 TCPOPT_WINDOW << 16 | TCPOLEN_WINDOW << 8 | 1253 sc->sc_request_r_scale); 1254 optp += 4; 1255 } 1256 1257 if (sc->sc_flags & SCF_TIMESTAMP) { 1258 u_int32_t *lp = (u_int32_t *)(optp); 1259 1260 /* Form timestamp option as shown in appendix A of RFC 1323. */ 1261 *lp++ = htonl(TCPOPT_TSTAMP_HDR); 1262 *lp++ = htonl(ticks); 1263 *lp = htonl(sc->sc_tsrecent); 1264 optp += TCPOLEN_TSTAMP_APPA; 1265 } 1266 1267 #ifdef TCP_SIGNATURE 1268 /* 1269 * Handle TCP-MD5 passive opener response. 1270 */ 1271 if (sc->sc_flags & SCF_SIGNATURE) { 1272 u_int8_t *bp = optp; 1273 int i; 1274 1275 *bp++ = TCPOPT_SIGNATURE; 1276 *bp++ = TCPOLEN_SIGNATURE; 1277 for (i = 0; i < TCP_SIGLEN; i++) 1278 *bp++ = 0; 1279 tcpsignature_compute(m, 0, optlen, 1280 optp + 2, IPSEC_DIR_OUTBOUND); 1281 *bp++ = TCPOPT_NOP; 1282 *bp++ = TCPOPT_EOL; 1283 optp += TCPOLEN_SIGNATURE + 2; 1284 } 1285 #endif /* TCP_SIGNATURE */ 1286 1287 if (sc->sc_flags & SCF_SACK_PERMITTED) { 1288 *((u_int32_t *)optp) = htonl(TCPOPT_SACK_PERMITTED_ALIGNED); 1289 optp += TCPOLEN_SACK_PERMITTED_ALIGNED; 1290 } 1291 1292 no_options: 1293 if (isipv6) { 1294 struct route_in6 *ro6 = &sc->sc_route6; 1295 1296 th->th_sum = 0; 1297 th->th_sum = in6_cksum(m, IPPROTO_TCP, hlen, tlen - hlen); 1298 ip6->ip6_hlim = in6_selecthlim(NULL, 1299 ro6->ro_rt ? ro6->ro_rt->rt_ifp : NULL); 1300 error = ip6_output(m, NULL, ro6, 0, NULL, NULL, 1301 sc->sc_tp->t_inpcb); 1302 } else { 1303 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 1304 htons(tlen - hlen + IPPROTO_TCP)); 1305 m->m_pkthdr.csum_flags = CSUM_TCP; 1306 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 1307 error = ip_output(m, sc->sc_ipopts, &sc->sc_route, 1308 IP_DEBUGROUTE, NULL, sc->sc_tp->t_inpcb); 1309 } 1310 return (error); 1311 } 1312 1313 /* 1314 * cookie layers: 1315 * 1316 * |. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .| 1317 * | peer iss | 1318 * | MD5(laddr,faddr,secret,lport,fport) |. . . . . . .| 1319 * | 0 |(A)| | 1320 * (A): peer mss index 1321 */ 1322 1323 /* 1324 * The values below are chosen to minimize the size of the tcp_secret 1325 * table, as well as providing roughly a 16 second lifetime for the cookie. 1326 */ 1327 1328 #define SYNCOOKIE_WNDBITS 5 /* exposed bits for window indexing */ 1329 #define SYNCOOKIE_TIMESHIFT 1 /* scale ticks to window time units */ 1330 1331 #define SYNCOOKIE_WNDMASK ((1 << SYNCOOKIE_WNDBITS) - 1) 1332 #define SYNCOOKIE_NSECRETS (1 << SYNCOOKIE_WNDBITS) 1333 #define SYNCOOKIE_TIMEOUT \ 1334 (hz * (1 << SYNCOOKIE_WNDBITS) / (1 << SYNCOOKIE_TIMESHIFT)) 1335 #define SYNCOOKIE_DATAMASK ((3 << SYNCOOKIE_WNDBITS) | SYNCOOKIE_WNDMASK) 1336 1337 static struct { 1338 u_int32_t ts_secbits[4]; 1339 u_int ts_expire; 1340 } tcp_secret[SYNCOOKIE_NSECRETS]; 1341 1342 static int tcp_msstab[] = { 0, 536, 1460, 8960 }; 1343 1344 static MD5_CTX syn_ctx; 1345 1346 #define MD5Add(v) MD5Update(&syn_ctx, (u_char *)&v, sizeof(v)) 1347 1348 struct md5_add { 1349 u_int32_t laddr, faddr; 1350 u_int32_t secbits[4]; 1351 u_int16_t lport, fport; 1352 }; 1353 1354 #ifdef CTASSERT 1355 CTASSERT(sizeof(struct md5_add) == 28); 1356 #endif 1357 1358 /* 1359 * Consider the problem of a recreated (and retransmitted) cookie. If the 1360 * original SYN was accepted, the connection is established. The second 1361 * SYN is inflight, and if it arrives with an ISN that falls within the 1362 * receive window, the connection is killed. 1363 * 1364 * However, since cookies have other problems, this may not be worth 1365 * worrying about. 1366 */ 1367 1368 static u_int32_t 1369 syncookie_generate(struct syncache *sc) 1370 { 1371 u_int32_t md5_buffer[4]; 1372 u_int32_t data; 1373 int idx, i; 1374 struct md5_add add; 1375 #ifdef INET6 1376 const boolean_t isipv6 = sc->sc_inc.inc_isipv6; 1377 #else 1378 const boolean_t isipv6 = FALSE; 1379 #endif 1380 1381 idx = ((ticks << SYNCOOKIE_TIMESHIFT) / hz) & SYNCOOKIE_WNDMASK; 1382 if (tcp_secret[idx].ts_expire < ticks) { 1383 for (i = 0; i < 4; i++) 1384 tcp_secret[idx].ts_secbits[i] = karc4random(); 1385 tcp_secret[idx].ts_expire = ticks + SYNCOOKIE_TIMEOUT; 1386 } 1387 for (data = NELEM(tcp_msstab) - 1; data > 0; data--) 1388 if (tcp_msstab[data] <= sc->sc_peer_mss) 1389 break; 1390 data = (data << SYNCOOKIE_WNDBITS) | idx; 1391 data ^= sc->sc_irs; /* peer's iss */ 1392 MD5Init(&syn_ctx); 1393 if (isipv6) { 1394 MD5Add(sc->sc_inc.inc6_laddr); 1395 MD5Add(sc->sc_inc.inc6_faddr); 1396 add.laddr = 0; 1397 add.faddr = 0; 1398 } else { 1399 add.laddr = sc->sc_inc.inc_laddr.s_addr; 1400 add.faddr = sc->sc_inc.inc_faddr.s_addr; 1401 } 1402 add.lport = sc->sc_inc.inc_lport; 1403 add.fport = sc->sc_inc.inc_fport; 1404 add.secbits[0] = tcp_secret[idx].ts_secbits[0]; 1405 add.secbits[1] = tcp_secret[idx].ts_secbits[1]; 1406 add.secbits[2] = tcp_secret[idx].ts_secbits[2]; 1407 add.secbits[3] = tcp_secret[idx].ts_secbits[3]; 1408 MD5Add(add); 1409 MD5Final((u_char *)&md5_buffer, &syn_ctx); 1410 data ^= (md5_buffer[0] & ~SYNCOOKIE_WNDMASK); 1411 return (data); 1412 } 1413 1414 static struct syncache * 1415 syncookie_lookup(struct in_conninfo *inc, struct tcphdr *th, struct socket *so) 1416 { 1417 u_int32_t md5_buffer[4]; 1418 struct syncache *sc; 1419 u_int32_t data; 1420 int wnd, idx; 1421 struct md5_add add; 1422 1423 data = (th->th_ack - 1) ^ (th->th_seq - 1); /* remove ISS */ 1424 idx = data & SYNCOOKIE_WNDMASK; 1425 if (tcp_secret[idx].ts_expire < ticks || 1426 sototcpcb(so)->ts_recent + SYNCOOKIE_TIMEOUT < ticks) 1427 return (NULL); 1428 MD5Init(&syn_ctx); 1429 #ifdef INET6 1430 if (inc->inc_isipv6) { 1431 MD5Add(inc->inc6_laddr); 1432 MD5Add(inc->inc6_faddr); 1433 add.laddr = 0; 1434 add.faddr = 0; 1435 } else 1436 #endif 1437 { 1438 add.laddr = inc->inc_laddr.s_addr; 1439 add.faddr = inc->inc_faddr.s_addr; 1440 } 1441 add.lport = inc->inc_lport; 1442 add.fport = inc->inc_fport; 1443 add.secbits[0] = tcp_secret[idx].ts_secbits[0]; 1444 add.secbits[1] = tcp_secret[idx].ts_secbits[1]; 1445 add.secbits[2] = tcp_secret[idx].ts_secbits[2]; 1446 add.secbits[3] = tcp_secret[idx].ts_secbits[3]; 1447 MD5Add(add); 1448 MD5Final((u_char *)&md5_buffer, &syn_ctx); 1449 data ^= md5_buffer[0]; 1450 if (data & ~SYNCOOKIE_DATAMASK) 1451 return (NULL); 1452 data = data >> SYNCOOKIE_WNDBITS; 1453 1454 /* 1455 * Fill in the syncache values. 1456 * XXX duplicate code from syncache_add 1457 */ 1458 sc = kmalloc(sizeof(struct syncache), M_SYNCACHE, M_WAITOK|M_ZERO); 1459 sc->sc_ipopts = NULL; 1460 sc->sc_inc.inc_fport = inc->inc_fport; 1461 sc->sc_inc.inc_lport = inc->inc_lport; 1462 #ifdef INET6 1463 sc->sc_inc.inc_isipv6 = inc->inc_isipv6; 1464 if (inc->inc_isipv6) { 1465 sc->sc_inc.inc6_faddr = inc->inc6_faddr; 1466 sc->sc_inc.inc6_laddr = inc->inc6_laddr; 1467 sc->sc_route6.ro_rt = NULL; 1468 } else 1469 #endif 1470 { 1471 sc->sc_inc.inc_faddr = inc->inc_faddr; 1472 sc->sc_inc.inc_laddr = inc->inc_laddr; 1473 sc->sc_route.ro_rt = NULL; 1474 } 1475 sc->sc_irs = th->th_seq - 1; 1476 sc->sc_iss = th->th_ack - 1; 1477 wnd = ssb_space(&so->so_rcv); 1478 wnd = imax(wnd, 0); 1479 wnd = imin(wnd, TCP_MAXWIN); 1480 sc->sc_wnd = wnd; 1481 sc->sc_flags = 0; 1482 sc->sc_rxtslot = 0; 1483 sc->sc_peer_mss = tcp_msstab[data]; 1484 return (sc); 1485 } 1486