1 /*- 2 * Copyright (c) 2001 McAfee, Inc. 3 * Copyright (c) 2006 Andre Oppermann, Internet Business Solutions AG 4 * All rights reserved. 5 * 6 * This software was developed for the FreeBSD Project by Jonathan Lemon 7 * and McAfee Research, the Security Research Division of McAfee, Inc. under 8 * DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the 9 * DARPA CHATS research program. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33 #include <sys/cdefs.h> 34 __FBSDID("$FreeBSD$"); 35 36 #include "opt_inet.h" 37 #include "opt_inet6.h" 38 #include "opt_ipsec.h" 39 #include "opt_mac.h" 40 41 #include <sys/param.h> 42 #include <sys/systm.h> 43 #include <sys/kernel.h> 44 #include <sys/sysctl.h> 45 #include <sys/limits.h> 46 #include <sys/lock.h> 47 #include <sys/mutex.h> 48 #include <sys/malloc.h> 49 #include <sys/mbuf.h> 50 #include <sys/md5.h> 51 #include <sys/proc.h> /* for proc0 declaration */ 52 #include <sys/random.h> 53 #include <sys/socket.h> 54 #include <sys/socketvar.h> 55 #include <sys/syslog.h> 56 #include <sys/ucred.h> 57 #include <sys/vimage.h> 58 59 #include <vm/uma.h> 60 61 #include <net/if.h> 62 #include <net/route.h> 63 64 #include <netinet/in.h> 65 #include <netinet/in_systm.h> 66 #include <netinet/ip.h> 67 #include <netinet/in_var.h> 68 #include <netinet/in_pcb.h> 69 #include <netinet/ip_var.h> 70 #include <netinet/ip_options.h> 71 #ifdef INET6 72 #include <netinet/ip6.h> 73 #include <netinet/icmp6.h> 74 #include <netinet6/nd6.h> 75 #include <netinet6/ip6_var.h> 76 #include <netinet6/in6_pcb.h> 77 #endif 78 #include <netinet/tcp.h> 79 #include <netinet/tcp_fsm.h> 80 #include <netinet/tcp_seq.h> 81 #include <netinet/tcp_timer.h> 82 #include <netinet/tcp_var.h> 83 #include <netinet/tcp_syncache.h> 84 #include <netinet/tcp_offload.h> 85 #ifdef INET6 86 #include <netinet6/tcp6_var.h> 87 #endif 88 89 #ifdef IPSEC 90 #include <netipsec/ipsec.h> 91 #ifdef INET6 92 #include <netipsec/ipsec6.h> 93 #endif 94 #include <netipsec/key.h> 95 #endif /*IPSEC*/ 96 97 #include <machine/in_cksum.h> 98 99 #include <security/mac/mac_framework.h> 100 101 static int tcp_syncookies = 1; 102 SYSCTL_INT(_net_inet_tcp, OID_AUTO, syncookies, CTLFLAG_RW, 103 &tcp_syncookies, 0, 104 "Use TCP SYN cookies if the syncache overflows"); 105 106 static int tcp_syncookiesonly = 0; 107 SYSCTL_INT(_net_inet_tcp, OID_AUTO, syncookies_only, CTLFLAG_RW, 108 &tcp_syncookiesonly, 0, 109 "Use only TCP SYN cookies"); 110 111 #ifdef TCP_OFFLOAD_DISABLE 112 #define TOEPCB_ISSET(sc) (0) 113 #else 114 #define TOEPCB_ISSET(sc) ((sc)->sc_toepcb != NULL) 115 #endif 116 117 static void syncache_drop(struct syncache *, struct syncache_head *); 118 static void syncache_free(struct syncache *); 119 static void syncache_insert(struct syncache *, struct syncache_head *); 120 struct syncache *syncache_lookup(struct in_conninfo *, struct syncache_head **); 121 static int syncache_respond(struct syncache *); 122 static struct socket *syncache_socket(struct syncache *, struct socket *, 123 struct mbuf *m); 124 static void syncache_timeout(struct syncache *sc, struct syncache_head *sch, 125 int docallout); 126 static void syncache_timer(void *); 127 static void syncookie_generate(struct syncache_head *, struct syncache *, 128 u_int32_t *); 129 static struct syncache 130 *syncookie_lookup(struct in_conninfo *, struct syncache_head *, 131 struct syncache *, struct tcpopt *, struct tcphdr *, 132 struct socket *); 133 134 /* 135 * Transmit the SYN,ACK fewer times than TCP_MAXRXTSHIFT specifies. 136 * 3 retransmits corresponds to a timeout of 3 * (1 + 2 + 4 + 8) == 45 seconds, 137 * the odds are that the user has given up attempting to connect by then. 138 */ 139 #define SYNCACHE_MAXREXMTS 3 140 141 /* Arbitrary values */ 142 #define TCP_SYNCACHE_HASHSIZE 512 143 #define TCP_SYNCACHE_BUCKETLIMIT 30 144 145 static struct tcp_syncache tcp_syncache; 146 147 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, syncache, CTLFLAG_RW, 0, "TCP SYN cache"); 148 149 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp_syncache, OID_AUTO, 150 bucketlimit, CTLFLAG_RDTUN, 151 tcp_syncache.bucket_limit, 0, "Per-bucket hash limit for syncache"); 152 153 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp_syncache, OID_AUTO, 154 cachelimit, CTLFLAG_RDTUN, 155 tcp_syncache.cache_limit, 0, "Overall entry limit for syncache"); 156 157 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp_syncache, OID_AUTO, 158 count, CTLFLAG_RD, 159 tcp_syncache.cache_count, 0, "Current number of entries in syncache"); 160 161 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp_syncache, OID_AUTO, 162 hashsize, CTLFLAG_RDTUN, 163 tcp_syncache.hashsize, 0, "Size of TCP syncache hashtable"); 164 165 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp_syncache, OID_AUTO, 166 rexmtlimit, CTLFLAG_RW, 167 tcp_syncache.rexmt_limit, 0, "Limit on SYN/ACK retransmissions"); 168 169 int tcp_sc_rst_sock_fail = 1; 170 SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp_syncache, OID_AUTO, 171 rst_on_sock_fail, CTLFLAG_RW, 172 tcp_sc_rst_sock_fail, 0, "Send reset on socket allocation failure"); 173 174 static MALLOC_DEFINE(M_SYNCACHE, "syncache", "TCP syncache"); 175 176 #define SYNCACHE_HASH(inc, mask) \ 177 ((V_tcp_syncache.hash_secret ^ \ 178 (inc)->inc_faddr.s_addr ^ \ 179 ((inc)->inc_faddr.s_addr >> 16) ^ \ 180 (inc)->inc_fport ^ (inc)->inc_lport) & mask) 181 182 #define SYNCACHE_HASH6(inc, mask) \ 183 ((V_tcp_syncache.hash_secret ^ \ 184 (inc)->inc6_faddr.s6_addr32[0] ^ \ 185 (inc)->inc6_faddr.s6_addr32[3] ^ \ 186 (inc)->inc_fport ^ (inc)->inc_lport) & mask) 187 188 #define ENDPTS_EQ(a, b) ( \ 189 (a)->ie_fport == (b)->ie_fport && \ 190 (a)->ie_lport == (b)->ie_lport && \ 191 (a)->ie_faddr.s_addr == (b)->ie_faddr.s_addr && \ 192 (a)->ie_laddr.s_addr == (b)->ie_laddr.s_addr \ 193 ) 194 195 #define ENDPTS6_EQ(a, b) (memcmp(a, b, sizeof(*a)) == 0) 196 197 #define SCH_LOCK(sch) mtx_lock(&(sch)->sch_mtx) 198 #define SCH_UNLOCK(sch) mtx_unlock(&(sch)->sch_mtx) 199 #define SCH_LOCK_ASSERT(sch) mtx_assert(&(sch)->sch_mtx, MA_OWNED) 200 201 /* 202 * Requires the syncache entry to be already removed from the bucket list. 203 */ 204 static void 205 syncache_free(struct syncache *sc) 206 { 207 INIT_VNET_INET(curvnet); 208 209 if (sc->sc_ipopts) 210 (void) m_free(sc->sc_ipopts); 211 if (sc->sc_cred) 212 crfree(sc->sc_cred); 213 #ifdef MAC 214 mac_syncache_destroy(&sc->sc_label); 215 #endif 216 217 uma_zfree(V_tcp_syncache.zone, sc); 218 } 219 220 void 221 syncache_init(void) 222 { 223 INIT_VNET_INET(curvnet); 224 int i; 225 226 V_tcp_syncache.cache_count = 0; 227 V_tcp_syncache.hashsize = TCP_SYNCACHE_HASHSIZE; 228 V_tcp_syncache.bucket_limit = TCP_SYNCACHE_BUCKETLIMIT; 229 V_tcp_syncache.rexmt_limit = SYNCACHE_MAXREXMTS; 230 V_tcp_syncache.hash_secret = arc4random(); 231 232 TUNABLE_INT_FETCH("net.inet.tcp.syncache.hashsize", 233 &V_tcp_syncache.hashsize); 234 TUNABLE_INT_FETCH("net.inet.tcp.syncache.bucketlimit", 235 &V_tcp_syncache.bucket_limit); 236 if (!powerof2(V_tcp_syncache.hashsize) || 237 V_tcp_syncache.hashsize == 0) { 238 printf("WARNING: syncache hash size is not a power of 2.\n"); 239 V_tcp_syncache.hashsize = TCP_SYNCACHE_HASHSIZE; 240 } 241 V_tcp_syncache.hashmask = V_tcp_syncache.hashsize - 1; 242 243 /* Set limits. */ 244 V_tcp_syncache.cache_limit = 245 V_tcp_syncache.hashsize * V_tcp_syncache.bucket_limit; 246 TUNABLE_INT_FETCH("net.inet.tcp.syncache.cachelimit", 247 &V_tcp_syncache.cache_limit); 248 249 /* Allocate the hash table. */ 250 MALLOC(V_tcp_syncache.hashbase, struct syncache_head *, 251 V_tcp_syncache.hashsize * sizeof(struct syncache_head), 252 M_SYNCACHE, M_WAITOK | M_ZERO); 253 254 /* Initialize the hash buckets. */ 255 for (i = 0; i < V_tcp_syncache.hashsize; i++) { 256 TAILQ_INIT(&V_tcp_syncache.hashbase[i].sch_bucket); 257 mtx_init(&V_tcp_syncache.hashbase[i].sch_mtx, "tcp_sc_head", 258 NULL, MTX_DEF); 259 callout_init_mtx(&V_tcp_syncache.hashbase[i].sch_timer, 260 &V_tcp_syncache.hashbase[i].sch_mtx, 0); 261 V_tcp_syncache.hashbase[i].sch_length = 0; 262 } 263 264 /* Create the syncache entry zone. */ 265 V_tcp_syncache.zone = uma_zcreate("syncache", sizeof(struct syncache), 266 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 267 uma_zone_set_max(V_tcp_syncache.zone, V_tcp_syncache.cache_limit); 268 } 269 270 /* 271 * Inserts a syncache entry into the specified bucket row. 272 * Locks and unlocks the syncache_head autonomously. 273 */ 274 static void 275 syncache_insert(struct syncache *sc, struct syncache_head *sch) 276 { 277 INIT_VNET_INET(sch->sch_vnet); 278 struct syncache *sc2; 279 280 SCH_LOCK(sch); 281 282 /* 283 * Make sure that we don't overflow the per-bucket limit. 284 * If the bucket is full, toss the oldest element. 285 */ 286 if (sch->sch_length >= V_tcp_syncache.bucket_limit) { 287 KASSERT(!TAILQ_EMPTY(&sch->sch_bucket), 288 ("sch->sch_length incorrect")); 289 sc2 = TAILQ_LAST(&sch->sch_bucket, sch_head); 290 syncache_drop(sc2, sch); 291 V_tcpstat.tcps_sc_bucketoverflow++; 292 } 293 294 /* Put it into the bucket. */ 295 TAILQ_INSERT_HEAD(&sch->sch_bucket, sc, sc_hash); 296 sch->sch_length++; 297 298 /* Reinitialize the bucket row's timer. */ 299 if (sch->sch_length == 1) 300 sch->sch_nextc = ticks + INT_MAX; 301 syncache_timeout(sc, sch, 1); 302 303 SCH_UNLOCK(sch); 304 305 V_tcp_syncache.cache_count++; 306 V_tcpstat.tcps_sc_added++; 307 } 308 309 /* 310 * Remove and free entry from syncache bucket row. 311 * Expects locked syncache head. 312 */ 313 static void 314 syncache_drop(struct syncache *sc, struct syncache_head *sch) 315 { 316 INIT_VNET_INET(sch->sch_vnet); 317 318 SCH_LOCK_ASSERT(sch); 319 320 TAILQ_REMOVE(&sch->sch_bucket, sc, sc_hash); 321 sch->sch_length--; 322 323 #ifndef TCP_OFFLOAD_DISABLE 324 if (sc->sc_tu) 325 sc->sc_tu->tu_syncache_event(TOE_SC_DROP, sc->sc_toepcb); 326 #endif 327 syncache_free(sc); 328 V_tcp_syncache.cache_count--; 329 } 330 331 /* 332 * Engage/reengage time on bucket row. 333 */ 334 static void 335 syncache_timeout(struct syncache *sc, struct syncache_head *sch, int docallout) 336 { 337 sc->sc_rxttime = ticks + 338 TCPTV_RTOBASE * (tcp_backoff[sc->sc_rxmits]); 339 sc->sc_rxmits++; 340 if (TSTMP_LT(sc->sc_rxttime, sch->sch_nextc)) { 341 sch->sch_nextc = sc->sc_rxttime; 342 if (docallout) 343 callout_reset(&sch->sch_timer, sch->sch_nextc - ticks, 344 syncache_timer, (void *)sch); 345 } 346 } 347 348 /* 349 * Walk the timer queues, looking for SYN,ACKs that need to be retransmitted. 350 * If we have retransmitted an entry the maximum number of times, expire it. 351 * One separate timer for each bucket row. 352 */ 353 static void 354 syncache_timer(void *xsch) 355 { 356 struct syncache_head *sch = (struct syncache_head *)xsch; 357 INIT_VNET_INET(sch->sch_vnet); 358 struct syncache *sc, *nsc; 359 int tick = ticks; 360 char *s; 361 362 /* NB: syncache_head has already been locked by the callout. */ 363 SCH_LOCK_ASSERT(sch); 364 365 /* 366 * In the following cycle we may remove some entries and/or 367 * advance some timeouts, so re-initialize the bucket timer. 368 */ 369 sch->sch_nextc = tick + INT_MAX; 370 371 TAILQ_FOREACH_SAFE(sc, &sch->sch_bucket, sc_hash, nsc) { 372 /* 373 * We do not check if the listen socket still exists 374 * and accept the case where the listen socket may be 375 * gone by the time we resend the SYN/ACK. We do 376 * not expect this to happens often. If it does, 377 * then the RST will be sent by the time the remote 378 * host does the SYN/ACK->ACK. 379 */ 380 if (TSTMP_GT(sc->sc_rxttime, tick)) { 381 if (TSTMP_LT(sc->sc_rxttime, sch->sch_nextc)) 382 sch->sch_nextc = sc->sc_rxttime; 383 continue; 384 } 385 if (sc->sc_rxmits > V_tcp_syncache.rexmt_limit) { 386 if ((s = tcp_log_addrs(&sc->sc_inc, NULL, NULL, NULL))) { 387 log(LOG_DEBUG, "%s; %s: Retransmits exhausted, " 388 "giving up and removing syncache entry\n", 389 s, __func__); 390 free(s, M_TCPLOG); 391 } 392 syncache_drop(sc, sch); 393 V_tcpstat.tcps_sc_stale++; 394 continue; 395 } 396 if ((s = tcp_log_addrs(&sc->sc_inc, NULL, NULL, NULL))) { 397 log(LOG_DEBUG, "%s; %s: Response timeout, " 398 "retransmitting (%u) SYN|ACK\n", 399 s, __func__, sc->sc_rxmits); 400 free(s, M_TCPLOG); 401 } 402 403 (void) syncache_respond(sc); 404 V_tcpstat.tcps_sc_retransmitted++; 405 syncache_timeout(sc, sch, 0); 406 } 407 if (!TAILQ_EMPTY(&(sch)->sch_bucket)) 408 callout_reset(&(sch)->sch_timer, (sch)->sch_nextc - tick, 409 syncache_timer, (void *)(sch)); 410 } 411 412 /* 413 * Find an entry in the syncache. 414 * Returns always with locked syncache_head plus a matching entry or NULL. 415 */ 416 struct syncache * 417 syncache_lookup(struct in_conninfo *inc, struct syncache_head **schp) 418 { 419 INIT_VNET_INET(curvnet); 420 struct syncache *sc; 421 struct syncache_head *sch; 422 423 #ifdef INET6 424 if (inc->inc_isipv6) { 425 sch = &V_tcp_syncache.hashbase[ 426 SYNCACHE_HASH6(inc, V_tcp_syncache.hashmask)]; 427 *schp = sch; 428 429 SCH_LOCK(sch); 430 431 /* Circle through bucket row to find matching entry. */ 432 TAILQ_FOREACH(sc, &sch->sch_bucket, sc_hash) { 433 if (ENDPTS6_EQ(&inc->inc_ie, &sc->sc_inc.inc_ie)) 434 return (sc); 435 } 436 } else 437 #endif 438 { 439 sch = &V_tcp_syncache.hashbase[ 440 SYNCACHE_HASH(inc, V_tcp_syncache.hashmask)]; 441 *schp = sch; 442 443 SCH_LOCK(sch); 444 445 /* Circle through bucket row to find matching entry. */ 446 TAILQ_FOREACH(sc, &sch->sch_bucket, sc_hash) { 447 #ifdef INET6 448 if (sc->sc_inc.inc_isipv6) 449 continue; 450 #endif 451 if (ENDPTS_EQ(&inc->inc_ie, &sc->sc_inc.inc_ie)) 452 return (sc); 453 } 454 } 455 SCH_LOCK_ASSERT(*schp); 456 return (NULL); /* always returns with locked sch */ 457 } 458 459 /* 460 * This function is called when we get a RST for a 461 * non-existent connection, so that we can see if the 462 * connection is in the syn cache. If it is, zap it. 463 */ 464 void 465 syncache_chkrst(struct in_conninfo *inc, struct tcphdr *th) 466 { 467 INIT_VNET_INET(curvnet); 468 struct syncache *sc; 469 struct syncache_head *sch; 470 char *s = NULL; 471 472 sc = syncache_lookup(inc, &sch); /* returns locked sch */ 473 SCH_LOCK_ASSERT(sch); 474 475 /* 476 * Any RST to our SYN|ACK must not carry ACK, SYN or FIN flags. 477 * See RFC 793 page 65, section SEGMENT ARRIVES. 478 */ 479 if (th->th_flags & (TH_ACK|TH_SYN|TH_FIN)) { 480 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) 481 log(LOG_DEBUG, "%s; %s: Spurious RST with ACK, SYN or " 482 "FIN flag set, segment ignored\n", s, __func__); 483 V_tcpstat.tcps_badrst++; 484 goto done; 485 } 486 487 /* 488 * No corresponding connection was found in syncache. 489 * If syncookies are enabled and possibly exclusively 490 * used, or we are under memory pressure, a valid RST 491 * may not find a syncache entry. In that case we're 492 * done and no SYN|ACK retransmissions will happen. 493 * Otherwise the the RST was misdirected or spoofed. 494 */ 495 if (sc == NULL) { 496 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) 497 log(LOG_DEBUG, "%s; %s: Spurious RST without matching " 498 "syncache entry (possibly syncookie only), " 499 "segment ignored\n", s, __func__); 500 V_tcpstat.tcps_badrst++; 501 goto done; 502 } 503 504 /* 505 * If the RST bit is set, check the sequence number to see 506 * if this is a valid reset segment. 507 * RFC 793 page 37: 508 * In all states except SYN-SENT, all reset (RST) segments 509 * are validated by checking their SEQ-fields. A reset is 510 * valid if its sequence number is in the window. 511 * 512 * The sequence number in the reset segment is normally an 513 * echo of our outgoing acknowlegement numbers, but some hosts 514 * send a reset with the sequence number at the rightmost edge 515 * of our receive window, and we have to handle this case. 516 */ 517 if (SEQ_GEQ(th->th_seq, sc->sc_irs) && 518 SEQ_LEQ(th->th_seq, sc->sc_irs + sc->sc_wnd)) { 519 syncache_drop(sc, sch); 520 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) 521 log(LOG_DEBUG, "%s; %s: Our SYN|ACK was rejected, " 522 "connection attempt aborted by remote endpoint\n", 523 s, __func__); 524 V_tcpstat.tcps_sc_reset++; 525 } else { 526 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) 527 log(LOG_DEBUG, "%s; %s: RST with invalid SEQ %u != " 528 "IRS %u (+WND %u), segment ignored\n", 529 s, __func__, th->th_seq, sc->sc_irs, sc->sc_wnd); 530 V_tcpstat.tcps_badrst++; 531 } 532 533 done: 534 if (s != NULL) 535 free(s, M_TCPLOG); 536 SCH_UNLOCK(sch); 537 } 538 539 void 540 syncache_badack(struct in_conninfo *inc) 541 { 542 INIT_VNET_INET(curvnet); 543 struct syncache *sc; 544 struct syncache_head *sch; 545 546 sc = syncache_lookup(inc, &sch); /* returns locked sch */ 547 SCH_LOCK_ASSERT(sch); 548 if (sc != NULL) { 549 syncache_drop(sc, sch); 550 V_tcpstat.tcps_sc_badack++; 551 } 552 SCH_UNLOCK(sch); 553 } 554 555 void 556 syncache_unreach(struct in_conninfo *inc, struct tcphdr *th) 557 { 558 INIT_VNET_INET(curvnet); 559 struct syncache *sc; 560 struct syncache_head *sch; 561 562 sc = syncache_lookup(inc, &sch); /* returns locked sch */ 563 SCH_LOCK_ASSERT(sch); 564 if (sc == NULL) 565 goto done; 566 567 /* If the sequence number != sc_iss, then it's a bogus ICMP msg */ 568 if (ntohl(th->th_seq) != sc->sc_iss) 569 goto done; 570 571 /* 572 * If we've rertransmitted 3 times and this is our second error, 573 * we remove the entry. Otherwise, we allow it to continue on. 574 * This prevents us from incorrectly nuking an entry during a 575 * spurious network outage. 576 * 577 * See tcp_notify(). 578 */ 579 if ((sc->sc_flags & SCF_UNREACH) == 0 || sc->sc_rxmits < 3 + 1) { 580 sc->sc_flags |= SCF_UNREACH; 581 goto done; 582 } 583 syncache_drop(sc, sch); 584 V_tcpstat.tcps_sc_unreach++; 585 done: 586 SCH_UNLOCK(sch); 587 } 588 589 /* 590 * Build a new TCP socket structure from a syncache entry. 591 */ 592 static struct socket * 593 syncache_socket(struct syncache *sc, struct socket *lso, struct mbuf *m) 594 { 595 INIT_VNET_INET(lso->so_vnet); 596 struct inpcb *inp = NULL; 597 struct socket *so; 598 struct tcpcb *tp; 599 char *s; 600 601 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 602 603 /* 604 * Ok, create the full blown connection, and set things up 605 * as they would have been set up if we had created the 606 * connection when the SYN arrived. If we can't create 607 * the connection, abort it. 608 */ 609 so = sonewconn(lso, SS_ISCONNECTED); 610 if (so == NULL) { 611 /* 612 * Drop the connection; we will either send a RST or 613 * have the peer retransmit its SYN again after its 614 * RTO and try again. 615 */ 616 V_tcpstat.tcps_listendrop++; 617 if ((s = tcp_log_addrs(&sc->sc_inc, NULL, NULL, NULL))) { 618 log(LOG_DEBUG, "%s; %s: Socket create failed " 619 "due to limits or memory shortage\n", 620 s, __func__); 621 free(s, M_TCPLOG); 622 } 623 goto abort2; 624 } 625 #ifdef MAC 626 SOCK_LOCK(so); 627 mac_socketpeer_set_from_mbuf(m, so); 628 SOCK_UNLOCK(so); 629 #endif 630 631 inp = sotoinpcb(so); 632 inp->inp_inc.inc_fibnum = sc->sc_inc.inc_fibnum; 633 so->so_fibnum = sc->sc_inc.inc_fibnum; 634 INP_WLOCK(inp); 635 636 /* Insert new socket into PCB hash list. */ 637 inp->inp_inc.inc_isipv6 = sc->sc_inc.inc_isipv6; 638 #ifdef INET6 639 if (sc->sc_inc.inc_isipv6) { 640 inp->in6p_laddr = sc->sc_inc.inc6_laddr; 641 } else { 642 inp->inp_vflag &= ~INP_IPV6; 643 inp->inp_vflag |= INP_IPV4; 644 #endif 645 inp->inp_laddr = sc->sc_inc.inc_laddr; 646 #ifdef INET6 647 } 648 #endif 649 inp->inp_lport = sc->sc_inc.inc_lport; 650 if (in_pcbinshash(inp) != 0) { 651 /* 652 * Undo the assignments above if we failed to 653 * put the PCB on the hash lists. 654 */ 655 #ifdef INET6 656 if (sc->sc_inc.inc_isipv6) 657 inp->in6p_laddr = in6addr_any; 658 else 659 #endif 660 inp->inp_laddr.s_addr = INADDR_ANY; 661 inp->inp_lport = 0; 662 goto abort; 663 } 664 #ifdef IPSEC 665 /* Copy old policy into new socket's. */ 666 if (ipsec_copy_policy(sotoinpcb(lso)->inp_sp, inp->inp_sp)) 667 printf("syncache_socket: could not copy policy\n"); 668 #endif 669 #ifdef INET6 670 if (sc->sc_inc.inc_isipv6) { 671 struct inpcb *oinp = sotoinpcb(lso); 672 struct in6_addr laddr6; 673 struct sockaddr_in6 sin6; 674 /* 675 * Inherit socket options from the listening socket. 676 * Note that in6p_inputopts are not (and should not be) 677 * copied, since it stores previously received options and is 678 * used to detect if each new option is different than the 679 * previous one and hence should be passed to a user. 680 * If we copied in6p_inputopts, a user would not be able to 681 * receive options just after calling the accept system call. 682 */ 683 inp->inp_flags |= oinp->inp_flags & INP_CONTROLOPTS; 684 if (oinp->in6p_outputopts) 685 inp->in6p_outputopts = 686 ip6_copypktopts(oinp->in6p_outputopts, M_NOWAIT); 687 688 sin6.sin6_family = AF_INET6; 689 sin6.sin6_len = sizeof(sin6); 690 sin6.sin6_addr = sc->sc_inc.inc6_faddr; 691 sin6.sin6_port = sc->sc_inc.inc_fport; 692 sin6.sin6_flowinfo = sin6.sin6_scope_id = 0; 693 laddr6 = inp->in6p_laddr; 694 if (IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_laddr)) 695 inp->in6p_laddr = sc->sc_inc.inc6_laddr; 696 if (in6_pcbconnect(inp, (struct sockaddr *)&sin6, 697 thread0.td_ucred)) { 698 inp->in6p_laddr = laddr6; 699 goto abort; 700 } 701 /* Override flowlabel from in6_pcbconnect. */ 702 inp->in6p_flowinfo &= ~IPV6_FLOWLABEL_MASK; 703 inp->in6p_flowinfo |= sc->sc_flowlabel; 704 } else 705 #endif 706 { 707 struct in_addr laddr; 708 struct sockaddr_in sin; 709 710 inp->inp_options = (m) ? ip_srcroute(m) : NULL; 711 712 if (inp->inp_options == NULL) { 713 inp->inp_options = sc->sc_ipopts; 714 sc->sc_ipopts = NULL; 715 } 716 717 sin.sin_family = AF_INET; 718 sin.sin_len = sizeof(sin); 719 sin.sin_addr = sc->sc_inc.inc_faddr; 720 sin.sin_port = sc->sc_inc.inc_fport; 721 bzero((caddr_t)sin.sin_zero, sizeof(sin.sin_zero)); 722 laddr = inp->inp_laddr; 723 if (inp->inp_laddr.s_addr == INADDR_ANY) 724 inp->inp_laddr = sc->sc_inc.inc_laddr; 725 if (in_pcbconnect(inp, (struct sockaddr *)&sin, 726 thread0.td_ucred)) { 727 inp->inp_laddr = laddr; 728 goto abort; 729 } 730 } 731 tp = intotcpcb(inp); 732 tp->t_state = TCPS_SYN_RECEIVED; 733 tp->iss = sc->sc_iss; 734 tp->irs = sc->sc_irs; 735 tcp_rcvseqinit(tp); 736 tcp_sendseqinit(tp); 737 tp->snd_wl1 = sc->sc_irs; 738 tp->snd_max = tp->iss + 1; 739 tp->snd_nxt = tp->iss + 1; 740 tp->rcv_up = sc->sc_irs + 1; 741 tp->rcv_wnd = sc->sc_wnd; 742 tp->rcv_adv += tp->rcv_wnd; 743 tp->last_ack_sent = tp->rcv_nxt; 744 745 tp->t_flags = sototcpcb(lso)->t_flags & (TF_NOPUSH|TF_NODELAY); 746 if (sc->sc_flags & SCF_NOOPT) 747 tp->t_flags |= TF_NOOPT; 748 else { 749 if (sc->sc_flags & SCF_WINSCALE) { 750 tp->t_flags |= TF_REQ_SCALE|TF_RCVD_SCALE; 751 tp->snd_scale = sc->sc_requested_s_scale; 752 tp->request_r_scale = sc->sc_requested_r_scale; 753 } 754 if (sc->sc_flags & SCF_TIMESTAMP) { 755 tp->t_flags |= TF_REQ_TSTMP|TF_RCVD_TSTMP; 756 tp->ts_recent = sc->sc_tsreflect; 757 tp->ts_recent_age = ticks; 758 tp->ts_offset = sc->sc_tsoff; 759 } 760 #ifdef TCP_SIGNATURE 761 if (sc->sc_flags & SCF_SIGNATURE) 762 tp->t_flags |= TF_SIGNATURE; 763 #endif 764 if (sc->sc_flags & SCF_SACK) 765 tp->t_flags |= TF_SACK_PERMIT; 766 } 767 768 if (sc->sc_flags & SCF_ECN) 769 tp->t_flags |= TF_ECN_PERMIT; 770 771 /* 772 * Set up MSS and get cached values from tcp_hostcache. 773 * This might overwrite some of the defaults we just set. 774 */ 775 tcp_mss(tp, sc->sc_peer_mss); 776 777 /* 778 * If the SYN,ACK was retransmitted, reset cwnd to 1 segment. 779 */ 780 if (sc->sc_rxmits) 781 tp->snd_cwnd = tp->t_maxseg; 782 tcp_timer_activate(tp, TT_KEEP, tcp_keepinit); 783 784 INP_WUNLOCK(inp); 785 786 V_tcpstat.tcps_accepts++; 787 return (so); 788 789 abort: 790 INP_WUNLOCK(inp); 791 abort2: 792 if (so != NULL) 793 soabort(so); 794 return (NULL); 795 } 796 797 /* 798 * This function gets called when we receive an ACK for a 799 * socket in the LISTEN state. We look up the connection 800 * in the syncache, and if its there, we pull it out of 801 * the cache and turn it into a full-blown connection in 802 * the SYN-RECEIVED state. 803 */ 804 int 805 syncache_expand(struct in_conninfo *inc, struct tcpopt *to, struct tcphdr *th, 806 struct socket **lsop, struct mbuf *m) 807 { 808 INIT_VNET_INET(curvnet); 809 struct syncache *sc; 810 struct syncache_head *sch; 811 struct syncache scs; 812 char *s; 813 814 /* 815 * Global TCP locks are held because we manipulate the PCB lists 816 * and create a new socket. 817 */ 818 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 819 KASSERT((th->th_flags & (TH_RST|TH_ACK|TH_SYN)) == TH_ACK, 820 ("%s: can handle only ACK", __func__)); 821 822 sc = syncache_lookup(inc, &sch); /* returns locked sch */ 823 SCH_LOCK_ASSERT(sch); 824 if (sc == NULL) { 825 /* 826 * There is no syncache entry, so see if this ACK is 827 * a returning syncookie. To do this, first: 828 * A. See if this socket has had a syncache entry dropped in 829 * the past. We don't want to accept a bogus syncookie 830 * if we've never received a SYN. 831 * B. check that the syncookie is valid. If it is, then 832 * cobble up a fake syncache entry, and return. 833 */ 834 if (!tcp_syncookies) { 835 SCH_UNLOCK(sch); 836 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) 837 log(LOG_DEBUG, "%s; %s: Spurious ACK, " 838 "segment rejected (syncookies disabled)\n", 839 s, __func__); 840 goto failed; 841 } 842 bzero(&scs, sizeof(scs)); 843 sc = syncookie_lookup(inc, sch, &scs, to, th, *lsop); 844 SCH_UNLOCK(sch); 845 if (sc == NULL) { 846 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) 847 log(LOG_DEBUG, "%s; %s: Segment failed " 848 "SYNCOOKIE authentication, segment rejected " 849 "(probably spoofed)\n", s, __func__); 850 goto failed; 851 } 852 } else { 853 /* Pull out the entry to unlock the bucket row. */ 854 TAILQ_REMOVE(&sch->sch_bucket, sc, sc_hash); 855 sch->sch_length--; 856 V_tcp_syncache.cache_count--; 857 SCH_UNLOCK(sch); 858 } 859 860 /* 861 * Segment validation: 862 * ACK must match our initial sequence number + 1 (the SYN|ACK). 863 */ 864 if (th->th_ack != sc->sc_iss + 1 && !TOEPCB_ISSET(sc)) { 865 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) 866 log(LOG_DEBUG, "%s; %s: ACK %u != ISS+1 %u, segment " 867 "rejected\n", s, __func__, th->th_ack, sc->sc_iss); 868 goto failed; 869 } 870 871 /* 872 * The SEQ must fall in the window starting at the received 873 * initial receive sequence number + 1 (the SYN). 874 */ 875 if ((SEQ_LEQ(th->th_seq, sc->sc_irs) || 876 SEQ_GT(th->th_seq, sc->sc_irs + sc->sc_wnd)) && 877 !TOEPCB_ISSET(sc)) { 878 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) 879 log(LOG_DEBUG, "%s; %s: SEQ %u != IRS+1 %u, segment " 880 "rejected\n", s, __func__, th->th_seq, sc->sc_irs); 881 goto failed; 882 } 883 884 if (!(sc->sc_flags & SCF_TIMESTAMP) && (to->to_flags & TOF_TS)) { 885 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) 886 log(LOG_DEBUG, "%s; %s: Timestamp not expected, " 887 "segment rejected\n", s, __func__); 888 goto failed; 889 } 890 /* 891 * If timestamps were negotiated the reflected timestamp 892 * must be equal to what we actually sent in the SYN|ACK. 893 */ 894 if ((to->to_flags & TOF_TS) && to->to_tsecr != sc->sc_ts && 895 !TOEPCB_ISSET(sc)) { 896 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) 897 log(LOG_DEBUG, "%s; %s: TSECR %u != TS %u, " 898 "segment rejected\n", 899 s, __func__, to->to_tsecr, sc->sc_ts); 900 goto failed; 901 } 902 903 *lsop = syncache_socket(sc, *lsop, m); 904 905 if (*lsop == NULL) 906 V_tcpstat.tcps_sc_aborted++; 907 else 908 V_tcpstat.tcps_sc_completed++; 909 910 /* how do we find the inp for the new socket? */ 911 if (sc != &scs) 912 syncache_free(sc); 913 return (1); 914 failed: 915 if (sc != NULL && sc != &scs) 916 syncache_free(sc); 917 if (s != NULL) 918 free(s, M_TCPLOG); 919 *lsop = NULL; 920 return (0); 921 } 922 923 int 924 tcp_offload_syncache_expand(struct in_conninfo *inc, struct tcpopt *to, 925 struct tcphdr *th, struct socket **lsop, struct mbuf *m) 926 { 927 int rc; 928 929 INP_INFO_WLOCK(&V_tcbinfo); 930 rc = syncache_expand(inc, to, th, lsop, m); 931 INP_INFO_WUNLOCK(&V_tcbinfo); 932 933 return (rc); 934 } 935 936 /* 937 * Given a LISTEN socket and an inbound SYN request, add 938 * this to the syn cache, and send back a segment: 939 * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK> 940 * to the source. 941 * 942 * IMPORTANT NOTE: We do _NOT_ ACK data that might accompany the SYN. 943 * Doing so would require that we hold onto the data and deliver it 944 * to the application. However, if we are the target of a SYN-flood 945 * DoS attack, an attacker could send data which would eventually 946 * consume all available buffer space if it were ACKed. By not ACKing 947 * the data, we avoid this DoS scenario. 948 */ 949 static void 950 _syncache_add(struct in_conninfo *inc, struct tcpopt *to, struct tcphdr *th, 951 struct inpcb *inp, struct socket **lsop, struct mbuf *m, 952 struct toe_usrreqs *tu, void *toepcb) 953 { 954 INIT_VNET_INET(inp->inp_vnet); 955 struct tcpcb *tp; 956 struct socket *so; 957 struct syncache *sc = NULL; 958 struct syncache_head *sch; 959 struct mbuf *ipopts = NULL; 960 u_int32_t flowtmp; 961 int win, sb_hiwat, ip_ttl, ip_tos, noopt; 962 char *s; 963 #ifdef INET6 964 int autoflowlabel = 0; 965 #endif 966 #ifdef MAC 967 struct label *maclabel; 968 #endif 969 struct syncache scs; 970 struct ucred *cred; 971 972 INP_INFO_WLOCK_ASSERT(&V_tcbinfo); 973 INP_WLOCK_ASSERT(inp); /* listen socket */ 974 KASSERT((th->th_flags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN, 975 ("%s: unexpected tcp flags", __func__)); 976 977 /* 978 * Combine all so/tp operations very early to drop the INP lock as 979 * soon as possible. 980 */ 981 so = *lsop; 982 tp = sototcpcb(so); 983 cred = crhold(so->so_cred); 984 985 #ifdef INET6 986 if (inc->inc_isipv6 && 987 (inp->in6p_flags & IN6P_AUTOFLOWLABEL)) 988 autoflowlabel = 1; 989 #endif 990 ip_ttl = inp->inp_ip_ttl; 991 ip_tos = inp->inp_ip_tos; 992 win = sbspace(&so->so_rcv); 993 sb_hiwat = so->so_rcv.sb_hiwat; 994 noopt = (tp->t_flags & TF_NOOPT); 995 996 /* By the time we drop the lock these should no longer be used. */ 997 so = NULL; 998 tp = NULL; 999 1000 #ifdef MAC 1001 if (mac_syncache_init(&maclabel) != 0) { 1002 INP_WUNLOCK(inp); 1003 INP_INFO_WUNLOCK(&V_tcbinfo); 1004 goto done; 1005 } else 1006 mac_syncache_create(maclabel, inp); 1007 #endif 1008 INP_WUNLOCK(inp); 1009 INP_INFO_WUNLOCK(&V_tcbinfo); 1010 1011 /* 1012 * Remember the IP options, if any. 1013 */ 1014 #ifdef INET6 1015 if (!inc->inc_isipv6) 1016 #endif 1017 ipopts = (m) ? ip_srcroute(m) : NULL; 1018 1019 /* 1020 * See if we already have an entry for this connection. 1021 * If we do, resend the SYN,ACK, and reset the retransmit timer. 1022 * 1023 * XXX: should the syncache be re-initialized with the contents 1024 * of the new SYN here (which may have different options?) 1025 * 1026 * XXX: We do not check the sequence number to see if this is a 1027 * real retransmit or a new connection attempt. The question is 1028 * how to handle such a case; either ignore it as spoofed, or 1029 * drop the current entry and create a new one? 1030 */ 1031 sc = syncache_lookup(inc, &sch); /* returns locked entry */ 1032 SCH_LOCK_ASSERT(sch); 1033 if (sc != NULL) { 1034 #ifndef TCP_OFFLOAD_DISABLE 1035 if (sc->sc_tu) 1036 sc->sc_tu->tu_syncache_event(TOE_SC_ENTRY_PRESENT, 1037 sc->sc_toepcb); 1038 #endif 1039 V_tcpstat.tcps_sc_dupsyn++; 1040 if (ipopts) { 1041 /* 1042 * If we were remembering a previous source route, 1043 * forget it and use the new one we've been given. 1044 */ 1045 if (sc->sc_ipopts) 1046 (void) m_free(sc->sc_ipopts); 1047 sc->sc_ipopts = ipopts; 1048 } 1049 /* 1050 * Update timestamp if present. 1051 */ 1052 if ((sc->sc_flags & SCF_TIMESTAMP) && (to->to_flags & TOF_TS)) 1053 sc->sc_tsreflect = to->to_tsval; 1054 else 1055 sc->sc_flags &= ~SCF_TIMESTAMP; 1056 #ifdef MAC 1057 /* 1058 * Since we have already unconditionally allocated label 1059 * storage, free it up. The syncache entry will already 1060 * have an initialized label we can use. 1061 */ 1062 mac_syncache_destroy(&maclabel); 1063 KASSERT(sc->sc_label != NULL, 1064 ("%s: label not initialized", __func__)); 1065 #endif 1066 /* Retransmit SYN|ACK and reset retransmit count. */ 1067 if ((s = tcp_log_addrs(&sc->sc_inc, th, NULL, NULL))) { 1068 log(LOG_DEBUG, "%s; %s: Received duplicate SYN, " 1069 "resetting timer and retransmitting SYN|ACK\n", 1070 s, __func__); 1071 free(s, M_TCPLOG); 1072 } 1073 if (!TOEPCB_ISSET(sc) && syncache_respond(sc) == 0) { 1074 sc->sc_rxmits = 0; 1075 syncache_timeout(sc, sch, 1); 1076 V_tcpstat.tcps_sndacks++; 1077 V_tcpstat.tcps_sndtotal++; 1078 } 1079 SCH_UNLOCK(sch); 1080 goto done; 1081 } 1082 1083 sc = uma_zalloc(V_tcp_syncache.zone, M_NOWAIT | M_ZERO); 1084 if (sc == NULL) { 1085 /* 1086 * The zone allocator couldn't provide more entries. 1087 * Treat this as if the cache was full; drop the oldest 1088 * entry and insert the new one. 1089 */ 1090 V_tcpstat.tcps_sc_zonefail++; 1091 if ((sc = TAILQ_LAST(&sch->sch_bucket, sch_head)) != NULL) 1092 syncache_drop(sc, sch); 1093 sc = uma_zalloc(V_tcp_syncache.zone, M_NOWAIT | M_ZERO); 1094 if (sc == NULL) { 1095 if (tcp_syncookies) { 1096 bzero(&scs, sizeof(scs)); 1097 sc = &scs; 1098 } else { 1099 SCH_UNLOCK(sch); 1100 if (ipopts) 1101 (void) m_free(ipopts); 1102 goto done; 1103 } 1104 } 1105 } 1106 1107 /* 1108 * Fill in the syncache values. 1109 */ 1110 #ifdef MAC 1111 sc->sc_label = maclabel; 1112 #endif 1113 sc->sc_cred = cred; 1114 cred = NULL; 1115 sc->sc_ipopts = ipopts; 1116 sc->sc_inc.inc_fibnum = inp->inp_inc.inc_fibnum; 1117 bcopy(inc, &sc->sc_inc, sizeof(struct in_conninfo)); 1118 #ifdef INET6 1119 if (!inc->inc_isipv6) 1120 #endif 1121 { 1122 sc->sc_ip_tos = ip_tos; 1123 sc->sc_ip_ttl = ip_ttl; 1124 } 1125 #ifndef TCP_OFFLOAD_DISABLE 1126 sc->sc_tu = tu; 1127 sc->sc_toepcb = toepcb; 1128 #endif 1129 sc->sc_irs = th->th_seq; 1130 sc->sc_iss = arc4random(); 1131 sc->sc_flags = 0; 1132 sc->sc_flowlabel = 0; 1133 1134 /* 1135 * Initial receive window: clip sbspace to [0 .. TCP_MAXWIN]. 1136 * win was derived from socket earlier in the function. 1137 */ 1138 win = imax(win, 0); 1139 win = imin(win, TCP_MAXWIN); 1140 sc->sc_wnd = win; 1141 1142 if (V_tcp_do_rfc1323) { 1143 /* 1144 * A timestamp received in a SYN makes 1145 * it ok to send timestamp requests and replies. 1146 */ 1147 if (to->to_flags & TOF_TS) { 1148 sc->sc_tsreflect = to->to_tsval; 1149 sc->sc_ts = ticks; 1150 sc->sc_flags |= SCF_TIMESTAMP; 1151 } 1152 if (to->to_flags & TOF_SCALE) { 1153 int wscale = 0; 1154 1155 /* 1156 * Pick the smallest possible scaling factor that 1157 * will still allow us to scale up to sb_max, aka 1158 * kern.ipc.maxsockbuf. 1159 * 1160 * We do this because there are broken firewalls that 1161 * will corrupt the window scale option, leading to 1162 * the other endpoint believing that our advertised 1163 * window is unscaled. At scale factors larger than 1164 * 5 the unscaled window will drop below 1500 bytes, 1165 * leading to serious problems when traversing these 1166 * broken firewalls. 1167 * 1168 * With the default maxsockbuf of 256K, a scale factor 1169 * of 3 will be chosen by this algorithm. Those who 1170 * choose a larger maxsockbuf should watch out 1171 * for the compatiblity problems mentioned above. 1172 * 1173 * RFC1323: The Window field in a SYN (i.e., a <SYN> 1174 * or <SYN,ACK>) segment itself is never scaled. 1175 */ 1176 while (wscale < TCP_MAX_WINSHIFT && 1177 (TCP_MAXWIN << wscale) < sb_max) 1178 wscale++; 1179 sc->sc_requested_r_scale = wscale; 1180 sc->sc_requested_s_scale = to->to_wscale; 1181 sc->sc_flags |= SCF_WINSCALE; 1182 } 1183 } 1184 #ifdef TCP_SIGNATURE 1185 /* 1186 * If listening socket requested TCP digests, and received SYN 1187 * contains the option, flag this in the syncache so that 1188 * syncache_respond() will do the right thing with the SYN+ACK. 1189 * XXX: Currently we always record the option by default and will 1190 * attempt to use it in syncache_respond(). 1191 */ 1192 if (to->to_flags & TOF_SIGNATURE) 1193 sc->sc_flags |= SCF_SIGNATURE; 1194 #endif 1195 if (to->to_flags & TOF_SACKPERM) 1196 sc->sc_flags |= SCF_SACK; 1197 if (to->to_flags & TOF_MSS) 1198 sc->sc_peer_mss = to->to_mss; /* peer mss may be zero */ 1199 if (noopt) 1200 sc->sc_flags |= SCF_NOOPT; 1201 if ((th->th_flags & (TH_ECE|TH_CWR)) && V_tcp_do_ecn) 1202 sc->sc_flags |= SCF_ECN; 1203 1204 if (tcp_syncookies) { 1205 syncookie_generate(sch, sc, &flowtmp); 1206 #ifdef INET6 1207 if (autoflowlabel) 1208 sc->sc_flowlabel = flowtmp; 1209 #endif 1210 } else { 1211 #ifdef INET6 1212 if (autoflowlabel) 1213 sc->sc_flowlabel = 1214 (htonl(ip6_randomflowlabel()) & IPV6_FLOWLABEL_MASK); 1215 #endif 1216 } 1217 SCH_UNLOCK(sch); 1218 1219 /* 1220 * Do a standard 3-way handshake. 1221 */ 1222 if (TOEPCB_ISSET(sc) || syncache_respond(sc) == 0) { 1223 if (tcp_syncookies && tcp_syncookiesonly && sc != &scs) 1224 syncache_free(sc); 1225 else if (sc != &scs) 1226 syncache_insert(sc, sch); /* locks and unlocks sch */ 1227 V_tcpstat.tcps_sndacks++; 1228 V_tcpstat.tcps_sndtotal++; 1229 } else { 1230 if (sc != &scs) 1231 syncache_free(sc); 1232 V_tcpstat.tcps_sc_dropped++; 1233 } 1234 1235 done: 1236 if (cred != NULL) 1237 crfree(cred); 1238 #ifdef MAC 1239 if (sc == &scs) 1240 mac_syncache_destroy(&maclabel); 1241 #endif 1242 if (m) { 1243 1244 *lsop = NULL; 1245 m_freem(m); 1246 } 1247 return; 1248 } 1249 1250 static int 1251 syncache_respond(struct syncache *sc) 1252 { 1253 INIT_VNET_INET(curvnet); 1254 struct ip *ip = NULL; 1255 struct mbuf *m; 1256 struct tcphdr *th; 1257 int optlen, error; 1258 u_int16_t hlen, tlen, mssopt; 1259 struct tcpopt to; 1260 #ifdef INET6 1261 struct ip6_hdr *ip6 = NULL; 1262 #endif 1263 1264 hlen = 1265 #ifdef INET6 1266 (sc->sc_inc.inc_isipv6) ? sizeof(struct ip6_hdr) : 1267 #endif 1268 sizeof(struct ip); 1269 tlen = hlen + sizeof(struct tcphdr); 1270 1271 /* Determine MSS we advertize to other end of connection. */ 1272 mssopt = tcp_mssopt(&sc->sc_inc); 1273 if (sc->sc_peer_mss) 1274 mssopt = max( min(sc->sc_peer_mss, mssopt), V_tcp_minmss); 1275 1276 /* XXX: Assume that the entire packet will fit in a header mbuf. */ 1277 KASSERT(max_linkhdr + tlen + TCP_MAXOLEN <= MHLEN, 1278 ("syncache: mbuf too small")); 1279 1280 /* Create the IP+TCP header from scratch. */ 1281 m = m_gethdr(M_DONTWAIT, MT_DATA); 1282 if (m == NULL) 1283 return (ENOBUFS); 1284 #ifdef MAC 1285 mac_syncache_create_mbuf(sc->sc_label, m); 1286 #endif 1287 m->m_data += max_linkhdr; 1288 m->m_len = tlen; 1289 m->m_pkthdr.len = tlen; 1290 m->m_pkthdr.rcvif = NULL; 1291 1292 #ifdef INET6 1293 if (sc->sc_inc.inc_isipv6) { 1294 ip6 = mtod(m, struct ip6_hdr *); 1295 ip6->ip6_vfc = IPV6_VERSION; 1296 ip6->ip6_nxt = IPPROTO_TCP; 1297 ip6->ip6_src = sc->sc_inc.inc6_laddr; 1298 ip6->ip6_dst = sc->sc_inc.inc6_faddr; 1299 ip6->ip6_plen = htons(tlen - hlen); 1300 /* ip6_hlim is set after checksum */ 1301 ip6->ip6_flow &= ~IPV6_FLOWLABEL_MASK; 1302 ip6->ip6_flow |= sc->sc_flowlabel; 1303 1304 th = (struct tcphdr *)(ip6 + 1); 1305 } else 1306 #endif 1307 { 1308 ip = mtod(m, struct ip *); 1309 ip->ip_v = IPVERSION; 1310 ip->ip_hl = sizeof(struct ip) >> 2; 1311 ip->ip_len = tlen; 1312 ip->ip_id = 0; 1313 ip->ip_off = 0; 1314 ip->ip_sum = 0; 1315 ip->ip_p = IPPROTO_TCP; 1316 ip->ip_src = sc->sc_inc.inc_laddr; 1317 ip->ip_dst = sc->sc_inc.inc_faddr; 1318 ip->ip_ttl = sc->sc_ip_ttl; 1319 ip->ip_tos = sc->sc_ip_tos; 1320 1321 /* 1322 * See if we should do MTU discovery. Route lookups are 1323 * expensive, so we will only unset the DF bit if: 1324 * 1325 * 1) path_mtu_discovery is disabled 1326 * 2) the SCF_UNREACH flag has been set 1327 */ 1328 if (V_path_mtu_discovery && ((sc->sc_flags & SCF_UNREACH) == 0)) 1329 ip->ip_off |= IP_DF; 1330 1331 th = (struct tcphdr *)(ip + 1); 1332 } 1333 th->th_sport = sc->sc_inc.inc_lport; 1334 th->th_dport = sc->sc_inc.inc_fport; 1335 1336 th->th_seq = htonl(sc->sc_iss); 1337 th->th_ack = htonl(sc->sc_irs + 1); 1338 th->th_off = sizeof(struct tcphdr) >> 2; 1339 th->th_x2 = 0; 1340 th->th_flags = TH_SYN|TH_ACK; 1341 th->th_win = htons(sc->sc_wnd); 1342 th->th_urp = 0; 1343 1344 if (sc->sc_flags & SCF_ECN) { 1345 th->th_flags |= TH_ECE; 1346 V_tcpstat.tcps_ecn_shs++; 1347 } 1348 1349 /* Tack on the TCP options. */ 1350 if ((sc->sc_flags & SCF_NOOPT) == 0) { 1351 to.to_flags = 0; 1352 1353 to.to_mss = mssopt; 1354 to.to_flags = TOF_MSS; 1355 if (sc->sc_flags & SCF_WINSCALE) { 1356 to.to_wscale = sc->sc_requested_r_scale; 1357 to.to_flags |= TOF_SCALE; 1358 } 1359 if (sc->sc_flags & SCF_TIMESTAMP) { 1360 /* Virgin timestamp or TCP cookie enhanced one. */ 1361 to.to_tsval = sc->sc_ts; 1362 to.to_tsecr = sc->sc_tsreflect; 1363 to.to_flags |= TOF_TS; 1364 } 1365 if (sc->sc_flags & SCF_SACK) 1366 to.to_flags |= TOF_SACKPERM; 1367 #ifdef TCP_SIGNATURE 1368 if (sc->sc_flags & SCF_SIGNATURE) 1369 to.to_flags |= TOF_SIGNATURE; 1370 #endif 1371 optlen = tcp_addoptions(&to, (u_char *)(th + 1)); 1372 1373 /* Adjust headers by option size. */ 1374 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 1375 m->m_len += optlen; 1376 m->m_pkthdr.len += optlen; 1377 1378 #ifdef TCP_SIGNATURE 1379 if (sc->sc_flags & SCF_SIGNATURE) 1380 tcp_signature_compute(m, 0, 0, optlen, 1381 to.to_signature, IPSEC_DIR_OUTBOUND); 1382 #endif 1383 #ifdef INET6 1384 if (sc->sc_inc.inc_isipv6) 1385 ip6->ip6_plen = htons(ntohs(ip6->ip6_plen) + optlen); 1386 else 1387 #endif 1388 ip->ip_len += optlen; 1389 } else 1390 optlen = 0; 1391 1392 #ifdef INET6 1393 if (sc->sc_inc.inc_isipv6) { 1394 th->th_sum = 0; 1395 th->th_sum = in6_cksum(m, IPPROTO_TCP, hlen, 1396 tlen + optlen - hlen); 1397 ip6->ip6_hlim = in6_selecthlim(NULL, NULL); 1398 error = ip6_output(m, NULL, NULL, 0, NULL, NULL, NULL); 1399 } else 1400 #endif 1401 { 1402 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 1403 htons(tlen + optlen - hlen + IPPROTO_TCP)); 1404 m->m_pkthdr.csum_flags = CSUM_TCP; 1405 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 1406 error = ip_output(m, sc->sc_ipopts, NULL, 0, NULL, NULL); 1407 } 1408 return (error); 1409 } 1410 1411 void 1412 syncache_add(struct in_conninfo *inc, struct tcpopt *to, struct tcphdr *th, 1413 struct inpcb *inp, struct socket **lsop, struct mbuf *m) 1414 { 1415 _syncache_add(inc, to, th, inp, lsop, m, NULL, NULL); 1416 } 1417 1418 void 1419 tcp_offload_syncache_add(struct in_conninfo *inc, struct tcpopt *to, 1420 struct tcphdr *th, struct inpcb *inp, struct socket **lsop, 1421 struct toe_usrreqs *tu, void *toepcb) 1422 { 1423 INIT_VNET_INET(curvnet); 1424 1425 INP_INFO_WLOCK(&V_tcbinfo); 1426 INP_WLOCK(inp); 1427 _syncache_add(inc, to, th, inp, lsop, NULL, tu, toepcb); 1428 } 1429 1430 /* 1431 * The purpose of SYN cookies is to avoid keeping track of all SYN's we 1432 * receive and to be able to handle SYN floods from bogus source addresses 1433 * (where we will never receive any reply). SYN floods try to exhaust all 1434 * our memory and available slots in the SYN cache table to cause a denial 1435 * of service to legitimate users of the local host. 1436 * 1437 * The idea of SYN cookies is to encode and include all necessary information 1438 * about the connection setup state within the SYN-ACK we send back and thus 1439 * to get along without keeping any local state until the ACK to the SYN-ACK 1440 * arrives (if ever). Everything we need to know should be available from 1441 * the information we encoded in the SYN-ACK. 1442 * 1443 * More information about the theory behind SYN cookies and its first 1444 * discussion and specification can be found at: 1445 * http://cr.yp.to/syncookies.html (overview) 1446 * http://cr.yp.to/syncookies/archive (gory details) 1447 * 1448 * This implementation extends the orginal idea and first implementation 1449 * of FreeBSD by using not only the initial sequence number field to store 1450 * information but also the timestamp field if present. This way we can 1451 * keep track of the entire state we need to know to recreate the session in 1452 * its original form. Almost all TCP speakers implement RFC1323 timestamps 1453 * these days. For those that do not we still have to live with the known 1454 * shortcomings of the ISN only SYN cookies. 1455 * 1456 * Cookie layers: 1457 * 1458 * Initial sequence number we send: 1459 * 31|................................|0 1460 * DDDDDDDDDDDDDDDDDDDDDDDDDMMMRRRP 1461 * D = MD5 Digest (first dword) 1462 * M = MSS index 1463 * R = Rotation of secret 1464 * P = Odd or Even secret 1465 * 1466 * The MD5 Digest is computed with over following parameters: 1467 * a) randomly rotated secret 1468 * b) struct in_conninfo containing the remote/local ip/port (IPv4&IPv6) 1469 * c) the received initial sequence number from remote host 1470 * d) the rotation offset and odd/even bit 1471 * 1472 * Timestamp we send: 1473 * 31|................................|0 1474 * DDDDDDDDDDDDDDDDDDDDDDSSSSRRRRA5 1475 * D = MD5 Digest (third dword) (only as filler) 1476 * S = Requested send window scale 1477 * R = Requested receive window scale 1478 * A = SACK allowed 1479 * 5 = TCP-MD5 enabled (not implemented yet) 1480 * XORed with MD5 Digest (forth dword) 1481 * 1482 * The timestamp isn't cryptographically secure and doesn't need to be. 1483 * The double use of the MD5 digest dwords ties it to a specific remote/ 1484 * local host/port, remote initial sequence number and our local time 1485 * limited secret. A received timestamp is reverted (XORed) and then 1486 * the contained MD5 dword is compared to the computed one to ensure the 1487 * timestamp belongs to the SYN-ACK we sent. The other parameters may 1488 * have been tampered with but this isn't different from supplying bogus 1489 * values in the SYN in the first place. 1490 * 1491 * Some problems with SYN cookies remain however: 1492 * Consider the problem of a recreated (and retransmitted) cookie. If the 1493 * original SYN was accepted, the connection is established. The second 1494 * SYN is inflight, and if it arrives with an ISN that falls within the 1495 * receive window, the connection is killed. 1496 * 1497 * Notes: 1498 * A heuristic to determine when to accept syn cookies is not necessary. 1499 * An ACK flood would cause the syncookie verification to be attempted, 1500 * but a SYN flood causes syncookies to be generated. Both are of equal 1501 * cost, so there's no point in trying to optimize the ACK flood case. 1502 * Also, if you don't process certain ACKs for some reason, then all someone 1503 * would have to do is launch a SYN and ACK flood at the same time, which 1504 * would stop cookie verification and defeat the entire purpose of syncookies. 1505 */ 1506 static int tcp_sc_msstab[] = { 0, 256, 468, 536, 996, 1452, 1460, 8960 }; 1507 1508 static void 1509 syncookie_generate(struct syncache_head *sch, struct syncache *sc, 1510 u_int32_t *flowlabel) 1511 { 1512 INIT_VNET_INET(curvnet); 1513 MD5_CTX ctx; 1514 u_int32_t md5_buffer[MD5_DIGEST_LENGTH / sizeof(u_int32_t)]; 1515 u_int32_t data; 1516 u_int32_t *secbits; 1517 u_int off, pmss, mss; 1518 int i; 1519 1520 SCH_LOCK_ASSERT(sch); 1521 1522 /* Which of the two secrets to use. */ 1523 secbits = sch->sch_oddeven ? 1524 sch->sch_secbits_odd : sch->sch_secbits_even; 1525 1526 /* Reseed secret if too old. */ 1527 if (sch->sch_reseed < time_uptime) { 1528 sch->sch_oddeven = sch->sch_oddeven ? 0 : 1; /* toggle */ 1529 secbits = sch->sch_oddeven ? 1530 sch->sch_secbits_odd : sch->sch_secbits_even; 1531 for (i = 0; i < SYNCOOKIE_SECRET_SIZE; i++) 1532 secbits[i] = arc4random(); 1533 sch->sch_reseed = time_uptime + SYNCOOKIE_LIFETIME; 1534 } 1535 1536 /* Secret rotation offset. */ 1537 off = sc->sc_iss & 0x7; /* iss was randomized before */ 1538 1539 /* Maximum segment size calculation. */ 1540 pmss = 1541 max( min(sc->sc_peer_mss, tcp_mssopt(&sc->sc_inc)), V_tcp_minmss); 1542 for (mss = sizeof(tcp_sc_msstab) / sizeof(int) - 1; mss > 0; mss--) 1543 if (tcp_sc_msstab[mss] <= pmss) 1544 break; 1545 1546 /* Fold parameters and MD5 digest into the ISN we will send. */ 1547 data = sch->sch_oddeven;/* odd or even secret, 1 bit */ 1548 data |= off << 1; /* secret offset, derived from iss, 3 bits */ 1549 data |= mss << 4; /* mss, 3 bits */ 1550 1551 MD5Init(&ctx); 1552 MD5Update(&ctx, ((u_int8_t *)secbits) + off, 1553 SYNCOOKIE_SECRET_SIZE * sizeof(*secbits) - off); 1554 MD5Update(&ctx, secbits, off); 1555 MD5Update(&ctx, &sc->sc_inc, sizeof(sc->sc_inc)); 1556 MD5Update(&ctx, &sc->sc_irs, sizeof(sc->sc_irs)); 1557 MD5Update(&ctx, &data, sizeof(data)); 1558 MD5Final((u_int8_t *)&md5_buffer, &ctx); 1559 1560 data |= (md5_buffer[0] << 7); 1561 sc->sc_iss = data; 1562 1563 #ifdef INET6 1564 *flowlabel = md5_buffer[1] & IPV6_FLOWLABEL_MASK; 1565 #endif 1566 1567 /* Additional parameters are stored in the timestamp if present. */ 1568 if (sc->sc_flags & SCF_TIMESTAMP) { 1569 data = ((sc->sc_flags & SCF_SIGNATURE) ? 1 : 0); /* TCP-MD5, 1 bit */ 1570 data |= ((sc->sc_flags & SCF_SACK) ? 1 : 0) << 1; /* SACK, 1 bit */ 1571 data |= sc->sc_requested_s_scale << 2; /* SWIN scale, 4 bits */ 1572 data |= sc->sc_requested_r_scale << 6; /* RWIN scale, 4 bits */ 1573 data |= md5_buffer[2] << 10; /* more digest bits */ 1574 data ^= md5_buffer[3]; 1575 sc->sc_ts = data; 1576 sc->sc_tsoff = data - ticks; /* after XOR */ 1577 } 1578 1579 V_tcpstat.tcps_sc_sendcookie++; 1580 return; 1581 } 1582 1583 static struct syncache * 1584 syncookie_lookup(struct in_conninfo *inc, struct syncache_head *sch, 1585 struct syncache *sc, struct tcpopt *to, struct tcphdr *th, 1586 struct socket *so) 1587 { 1588 INIT_VNET_INET(curvnet); 1589 MD5_CTX ctx; 1590 u_int32_t md5_buffer[MD5_DIGEST_LENGTH / sizeof(u_int32_t)]; 1591 u_int32_t data = 0; 1592 u_int32_t *secbits; 1593 tcp_seq ack, seq; 1594 int off, mss, wnd, flags; 1595 1596 SCH_LOCK_ASSERT(sch); 1597 1598 /* 1599 * Pull information out of SYN-ACK/ACK and 1600 * revert sequence number advances. 1601 */ 1602 ack = th->th_ack - 1; 1603 seq = th->th_seq - 1; 1604 off = (ack >> 1) & 0x7; 1605 mss = (ack >> 4) & 0x7; 1606 flags = ack & 0x7f; 1607 1608 /* Which of the two secrets to use. */ 1609 secbits = (flags & 0x1) ? sch->sch_secbits_odd : sch->sch_secbits_even; 1610 1611 /* 1612 * The secret wasn't updated for the lifetime of a syncookie, 1613 * so this SYN-ACK/ACK is either too old (replay) or totally bogus. 1614 */ 1615 if (sch->sch_reseed + SYNCOOKIE_LIFETIME < time_uptime) { 1616 return (NULL); 1617 } 1618 1619 /* Recompute the digest so we can compare it. */ 1620 MD5Init(&ctx); 1621 MD5Update(&ctx, ((u_int8_t *)secbits) + off, 1622 SYNCOOKIE_SECRET_SIZE * sizeof(*secbits) - off); 1623 MD5Update(&ctx, secbits, off); 1624 MD5Update(&ctx, inc, sizeof(*inc)); 1625 MD5Update(&ctx, &seq, sizeof(seq)); 1626 MD5Update(&ctx, &flags, sizeof(flags)); 1627 MD5Final((u_int8_t *)&md5_buffer, &ctx); 1628 1629 /* Does the digest part of or ACK'ed ISS match? */ 1630 if ((ack & (~0x7f)) != (md5_buffer[0] << 7)) 1631 return (NULL); 1632 1633 /* Does the digest part of our reflected timestamp match? */ 1634 if (to->to_flags & TOF_TS) { 1635 data = md5_buffer[3] ^ to->to_tsecr; 1636 if ((data & (~0x3ff)) != (md5_buffer[2] << 10)) 1637 return (NULL); 1638 } 1639 1640 /* Fill in the syncache values. */ 1641 bcopy(inc, &sc->sc_inc, sizeof(struct in_conninfo)); 1642 sc->sc_ipopts = NULL; 1643 1644 sc->sc_irs = seq; 1645 sc->sc_iss = ack; 1646 1647 #ifdef INET6 1648 if (inc->inc_isipv6) { 1649 if (sotoinpcb(so)->in6p_flags & IN6P_AUTOFLOWLABEL) 1650 sc->sc_flowlabel = md5_buffer[1] & IPV6_FLOWLABEL_MASK; 1651 } else 1652 #endif 1653 { 1654 sc->sc_ip_ttl = sotoinpcb(so)->inp_ip_ttl; 1655 sc->sc_ip_tos = sotoinpcb(so)->inp_ip_tos; 1656 } 1657 1658 /* Additional parameters that were encoded in the timestamp. */ 1659 if (data) { 1660 sc->sc_flags |= SCF_TIMESTAMP; 1661 sc->sc_tsreflect = to->to_tsval; 1662 sc->sc_ts = to->to_tsecr; 1663 sc->sc_tsoff = to->to_tsecr - ticks; 1664 sc->sc_flags |= (data & 0x1) ? SCF_SIGNATURE : 0; 1665 sc->sc_flags |= ((data >> 1) & 0x1) ? SCF_SACK : 0; 1666 sc->sc_requested_s_scale = min((data >> 2) & 0xf, 1667 TCP_MAX_WINSHIFT); 1668 sc->sc_requested_r_scale = min((data >> 6) & 0xf, 1669 TCP_MAX_WINSHIFT); 1670 if (sc->sc_requested_s_scale || sc->sc_requested_r_scale) 1671 sc->sc_flags |= SCF_WINSCALE; 1672 } else 1673 sc->sc_flags |= SCF_NOOPT; 1674 1675 wnd = sbspace(&so->so_rcv); 1676 wnd = imax(wnd, 0); 1677 wnd = imin(wnd, TCP_MAXWIN); 1678 sc->sc_wnd = wnd; 1679 1680 sc->sc_rxmits = 0; 1681 sc->sc_peer_mss = tcp_sc_msstab[mss]; 1682 1683 V_tcpstat.tcps_sc_recvcookie++; 1684 return (sc); 1685 } 1686 1687 /* 1688 * Returns the current number of syncache entries. This number 1689 * will probably change before you get around to calling 1690 * syncache_pcblist. 1691 */ 1692 1693 int 1694 syncache_pcbcount(void) 1695 { 1696 INIT_VNET_INET(curvnet); 1697 struct syncache_head *sch; 1698 int count, i; 1699 1700 for (count = 0, i = 0; i < V_tcp_syncache.hashsize; i++) { 1701 /* No need to lock for a read. */ 1702 sch = &V_tcp_syncache.hashbase[i]; 1703 count += sch->sch_length; 1704 } 1705 return count; 1706 } 1707 1708 /* 1709 * Exports the syncache entries to userland so that netstat can display 1710 * them alongside the other sockets. This function is intended to be 1711 * called only from tcp_pcblist. 1712 * 1713 * Due to concurrency on an active system, the number of pcbs exported 1714 * may have no relation to max_pcbs. max_pcbs merely indicates the 1715 * amount of space the caller allocated for this function to use. 1716 */ 1717 int 1718 syncache_pcblist(struct sysctl_req *req, int max_pcbs, int *pcbs_exported) 1719 { 1720 INIT_VNET_INET(curvnet); 1721 struct xtcpcb xt; 1722 struct syncache *sc; 1723 struct syncache_head *sch; 1724 int count, error, i; 1725 1726 for (count = 0, error = 0, i = 0; i < V_tcp_syncache.hashsize; i++) { 1727 sch = &V_tcp_syncache.hashbase[i]; 1728 SCH_LOCK(sch); 1729 TAILQ_FOREACH(sc, &sch->sch_bucket, sc_hash) { 1730 if (count >= max_pcbs) { 1731 SCH_UNLOCK(sch); 1732 goto exit; 1733 } 1734 if (cr_cansee(req->td->td_ucred, sc->sc_cred) != 0) 1735 continue; 1736 bzero(&xt, sizeof(xt)); 1737 xt.xt_len = sizeof(xt); 1738 if (sc->sc_inc.inc_isipv6) 1739 xt.xt_inp.inp_vflag = INP_IPV6; 1740 else 1741 xt.xt_inp.inp_vflag = INP_IPV4; 1742 bcopy(&sc->sc_inc, &xt.xt_inp.inp_inc, sizeof (struct in_conninfo)); 1743 xt.xt_tp.t_inpcb = &xt.xt_inp; 1744 xt.xt_tp.t_state = TCPS_SYN_RECEIVED; 1745 xt.xt_socket.xso_protocol = IPPROTO_TCP; 1746 xt.xt_socket.xso_len = sizeof (struct xsocket); 1747 xt.xt_socket.so_type = SOCK_STREAM; 1748 xt.xt_socket.so_state = SS_ISCONNECTING; 1749 error = SYSCTL_OUT(req, &xt, sizeof xt); 1750 if (error) { 1751 SCH_UNLOCK(sch); 1752 goto exit; 1753 } 1754 count++; 1755 } 1756 SCH_UNLOCK(sch); 1757 } 1758 exit: 1759 *pcbs_exported = count; 1760 return error; 1761 } 1762