2 * Copyright (c) 2003, 2004 Jeffrey M. Hsu. All rights reserved.
3 * Copyright (c) 2003, 2004 The DragonFly Project. All rights reserved.
5 * This code is derived from software contributed to The DragonFly Project
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
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.
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
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.
39 * Copyright (c) 2001 Networks Associates Technologies, Inc.
40 * All rights reserved.
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.
47 * Redistribution and use in source and binary forms, with or without
48 * modification, are permitted provided that the following conditions
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
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
71 * $FreeBSD: src/sys/netinet/tcp_syncache.c,v 1.5.2.14 2003/02/24 04:02:27 silby Exp $
75 #include "opt_inet6.h"
76 #include "opt_ipsec.h"
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>
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>
91 #include <sys/msgport2.h>
92 #include <net/netmsg2.h>
93 #include <net/netisr2.h>
96 #include <net/route.h>
98 #include <netinet/in.h>
99 #include <netinet/in_systm.h>
100 #include <netinet/ip.h>
101 #include <netinet/in_var.h>
102 #include <netinet/in_pcb.h>
103 #include <netinet/ip_var.h>
104 #include <netinet/ip6.h>
106 #include <netinet/icmp6.h>
107 #include <netinet6/nd6.h>
109 #include <netinet6/ip6_var.h>
110 #include <netinet6/in6_pcb.h>
111 #include <netinet/tcp.h>
112 #include <netinet/tcp_fsm.h>
113 #include <netinet/tcp_seq.h>
114 #include <netinet/tcp_timer.h>
115 #include <netinet/tcp_timer2.h>
116 #include <netinet/tcp_var.h>
117 #include <netinet6/tcp6_var.h>
120 #include <netinet6/ipsec.h>
122 #include <netinet6/ipsec6.h>
124 #include <netproto/key/key.h>
128 #include <netproto/ipsec/ipsec.h>
130 #include <netproto/ipsec/ipsec6.h>
132 #include <netproto/ipsec/key.h>
134 #endif /*FAST_IPSEC*/
136 static int tcp_syncookies = 1;
137 SYSCTL_INT(_net_inet_tcp, OID_AUTO, syncookies, CTLFLAG_RW,
139 "Use TCP SYN cookies if the syncache overflows");
141 static void syncache_drop(struct syncache *, struct syncache_head *);
142 static void syncache_free(struct syncache *);
143 static void syncache_insert(struct syncache *, struct syncache_head *);
144 struct syncache *syncache_lookup(struct in_conninfo *, struct syncache_head **);
145 static int syncache_respond(struct syncache *, struct mbuf *);
146 static struct socket *syncache_socket(struct syncache *, struct socket *,
148 static void syncache_timer(void *);
149 static u_int32_t syncookie_generate(struct syncache *);
150 static struct syncache *syncookie_lookup(struct in_conninfo *,
151 struct tcphdr *, struct socket *);
154 * Transmit the SYN,ACK fewer times than TCP_MAXRXTSHIFT specifies.
155 * 4 retransmits corresponds to a timeout of (3 + 3 + 3 + 3 + 3 == 15) seconds
156 * or (1 + 1 + 2 + 4 + 8 == 16) seconds if RFC6298 is used, the odds are that
157 * the user has given up attempting to connect by then.
159 #define SYNCACHE_MAXREXMTS 4
161 /* Arbitrary values */
162 #define TCP_SYNCACHE_HASHSIZE 512
163 #define TCP_SYNCACHE_BUCKETLIMIT 30
165 struct netmsg_sc_timer {
166 struct netmsg_base base;
167 struct msgrec *nm_mrec; /* back pointer to containing msgrec */
171 struct netmsg_sc_timer msg;
172 lwkt_port_t port; /* constant after init */
173 int slot; /* constant after init */
176 static void syncache_timer_handler(netmsg_t);
178 struct tcp_syncache {
186 static struct tcp_syncache tcp_syncache;
188 TAILQ_HEAD(syncache_list, syncache);
190 struct tcp_syncache_percpu {
191 struct syncache_head *hashbase;
193 struct syncache_list timerq[SYNCACHE_MAXREXMTS + 1];
194 struct callout tt_timerq[SYNCACHE_MAXREXMTS + 1];
195 struct msgrec mrec[SYNCACHE_MAXREXMTS + 1];
197 static struct tcp_syncache_percpu tcp_syncache_percpu[MAXCPU];
199 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, syncache, CTLFLAG_RW, 0, "TCP SYN cache");
201 SYSCTL_INT(_net_inet_tcp_syncache, OID_AUTO, bucketlimit, CTLFLAG_RD,
202 &tcp_syncache.bucket_limit, 0, "Per-bucket hash limit for syncache");
204 SYSCTL_INT(_net_inet_tcp_syncache, OID_AUTO, cachelimit, CTLFLAG_RD,
205 &tcp_syncache.cache_limit, 0, "Overall entry limit for syncache");
209 SYSCTL_INT(_net_inet_tcp_syncache, OID_AUTO, count, CTLFLAG_RD,
210 &tcp_syncache.cache_count, 0, "Current number of entries in syncache");
213 SYSCTL_INT(_net_inet_tcp_syncache, OID_AUTO, hashsize, CTLFLAG_RD,
214 &tcp_syncache.hashsize, 0, "Size of TCP syncache hashtable");
216 SYSCTL_INT(_net_inet_tcp_syncache, OID_AUTO, rexmtlimit, CTLFLAG_RW,
217 &tcp_syncache.rexmt_limit, 0, "Limit on SYN/ACK retransmissions");
219 static MALLOC_DEFINE(M_SYNCACHE, "syncache", "TCP syncache");
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)
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)
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 \
240 #define ENDPTS6_EQ(a, b) (memcmp(a, b, sizeof(*a)) == 0)
243 syncache_rto(int slot)
246 return (TCPTV_RTOBASE * tcp_syn_backoff_low[slot]);
248 return (TCPTV_RTOBASE * tcp_syn_backoff[slot]);
252 syncache_timeout(struct tcp_syncache_percpu *syncache_percpu,
253 struct syncache *sc, int slot)
259 * Record the time that we spent in SYN|ACK
262 * Needed by RFC3390 and RFC6298.
264 sc->sc_rxtused += syncache_rto(slot - 1);
266 sc->sc_rxtslot = slot;
268 rto = syncache_rto(slot);
269 sc->sc_rxttime = ticks + rto;
271 TAILQ_INSERT_TAIL(&syncache_percpu->timerq[slot], sc, sc_timerq);
272 if (!callout_active(&syncache_percpu->tt_timerq[slot])) {
273 callout_reset(&syncache_percpu->tt_timerq[slot], rto,
274 syncache_timer, &syncache_percpu->mrec[slot]);
279 syncache_free(struct syncache *sc)
283 const boolean_t isipv6 = sc->sc_inc.inc_isipv6;
285 const boolean_t isipv6 = FALSE;
289 m_free(sc->sc_ipopts);
291 rt = isipv6 ? sc->sc_route6.ro_rt : sc->sc_route.ro_rt;
294 * If this is the only reference to a protocol-cloned
295 * route, remove it immediately.
297 if ((rt->rt_flags & (RTF_WASCLONED | RTF_LLINFO)) ==
298 RTF_WASCLONED && rt->rt_refcnt == 1) {
299 rtrequest(RTM_DELETE, rt_key(rt), rt->rt_gateway,
300 rt_mask(rt), rt->rt_flags, NULL);
304 kfree(sc, M_SYNCACHE);
312 tcp_syncache.hashsize = TCP_SYNCACHE_HASHSIZE;
313 tcp_syncache.bucket_limit = TCP_SYNCACHE_BUCKETLIMIT;
314 tcp_syncache.cache_limit =
315 tcp_syncache.hashsize * tcp_syncache.bucket_limit;
316 tcp_syncache.rexmt_limit = SYNCACHE_MAXREXMTS;
317 tcp_syncache.hash_secret = karc4random();
319 TUNABLE_INT_FETCH("net.inet.tcp.syncache.hashsize",
320 &tcp_syncache.hashsize);
321 TUNABLE_INT_FETCH("net.inet.tcp.syncache.cachelimit",
322 &tcp_syncache.cache_limit);
323 TUNABLE_INT_FETCH("net.inet.tcp.syncache.bucketlimit",
324 &tcp_syncache.bucket_limit);
325 if (!powerof2(tcp_syncache.hashsize)) {
326 kprintf("WARNING: syncache hash size is not a power of 2.\n");
327 tcp_syncache.hashsize = 512; /* safe default */
329 tcp_syncache.hashmask = tcp_syncache.hashsize - 1;
331 for (cpu = 0; cpu < ncpus2; cpu++) {
332 struct tcp_syncache_percpu *syncache_percpu;
334 syncache_percpu = &tcp_syncache_percpu[cpu];
335 /* Allocate the hash table. */
336 syncache_percpu->hashbase = kmalloc(tcp_syncache.hashsize * sizeof(struct syncache_head),
337 M_SYNCACHE, M_WAITOK);
339 /* Initialize the hash buckets. */
340 for (i = 0; i < tcp_syncache.hashsize; i++) {
341 struct syncache_head *bucket;
343 bucket = &syncache_percpu->hashbase[i];
344 TAILQ_INIT(&bucket->sch_bucket);
345 bucket->sch_length = 0;
348 for (i = 0; i <= SYNCACHE_MAXREXMTS; i++) {
349 /* Initialize the timer queues. */
350 TAILQ_INIT(&syncache_percpu->timerq[i]);
351 callout_init_mp(&syncache_percpu->tt_timerq[i]);
353 syncache_percpu->mrec[i].slot = i;
354 syncache_percpu->mrec[i].port = netisr_cpuport(cpu);
355 syncache_percpu->mrec[i].msg.nm_mrec =
356 &syncache_percpu->mrec[i];
357 netmsg_init(&syncache_percpu->mrec[i].msg.base,
358 NULL, &netisr_adone_rport,
359 MSGF_PRIORITY, syncache_timer_handler);
365 syncache_insert(struct syncache *sc, struct syncache_head *sch)
367 struct tcp_syncache_percpu *syncache_percpu;
368 struct syncache *sc2;
371 syncache_percpu = &tcp_syncache_percpu[mycpu->gd_cpuid];
374 * Make sure that we don't overflow the per-bucket
375 * limit or the total cache size limit.
377 if (sch->sch_length >= tcp_syncache.bucket_limit) {
379 * The bucket is full, toss the oldest element.
381 sc2 = TAILQ_FIRST(&sch->sch_bucket);
382 if (sc2->sc_tp != NULL)
383 sc2->sc_tp->ts_recent = ticks;
384 syncache_drop(sc2, sch);
385 tcpstat.tcps_sc_bucketoverflow++;
386 } else if (syncache_percpu->cache_count >= tcp_syncache.cache_limit) {
388 * The cache is full. Toss the oldest entry in the
389 * entire cache. This is the front entry in the
390 * first non-empty timer queue with the largest
393 for (i = SYNCACHE_MAXREXMTS; i >= 0; i--) {
394 sc2 = TAILQ_FIRST(&syncache_percpu->timerq[i]);
395 while (sc2 && (sc2->sc_flags & SCF_MARKER))
396 sc2 = TAILQ_NEXT(sc2, sc_timerq);
400 if (sc2->sc_tp != NULL)
401 sc2->sc_tp->ts_recent = ticks;
402 syncache_drop(sc2, NULL);
403 tcpstat.tcps_sc_cacheoverflow++;
406 /* Initialize the entry's timer. */
407 syncache_timeout(syncache_percpu, sc, 0);
409 /* Put it into the bucket. */
410 TAILQ_INSERT_TAIL(&sch->sch_bucket, sc, sc_hash);
412 syncache_percpu->cache_count++;
413 tcpstat.tcps_sc_added++;
417 syncache_destroy(struct tcpcb *tp, struct tcpcb *tp_inh)
419 struct tcp_syncache_percpu *syncache_percpu;
420 struct syncache_head *bucket;
424 syncache_percpu = &tcp_syncache_percpu[mycpu->gd_cpuid];
427 for (i = 0; i < tcp_syncache.hashsize; i++) {
428 bucket = &syncache_percpu->hashbase[i];
429 TAILQ_FOREACH(sc, &bucket->sch_bucket, sc_hash) {
437 syncache_drop(struct syncache *sc, struct syncache_head *sch)
439 struct tcp_syncache_percpu *syncache_percpu;
441 const boolean_t isipv6 = sc->sc_inc.inc_isipv6;
443 const boolean_t isipv6 = FALSE;
446 syncache_percpu = &tcp_syncache_percpu[mycpu->gd_cpuid];
450 sch = &syncache_percpu->hashbase[
451 SYNCACHE_HASH6(&sc->sc_inc, tcp_syncache.hashmask)];
453 sch = &syncache_percpu->hashbase[
454 SYNCACHE_HASH(&sc->sc_inc, tcp_syncache.hashmask)];
458 TAILQ_REMOVE(&sch->sch_bucket, sc, sc_hash);
460 syncache_percpu->cache_count--;
468 * Remove the entry from the syncache timer/timeout queue. Note
469 * that we do not try to stop any running timer since we do not know
470 * whether the timer's message is in-transit or not. Since timeouts
471 * are fairly long, taking an unneeded callout does not detrimentally
472 * effect performance.
474 TAILQ_REMOVE(&syncache_percpu->timerq[sc->sc_rxtslot], sc, sc_timerq);
480 * Place a timeout message on the TCP thread's message queue.
481 * This routine runs in soft interrupt context.
483 * An invariant is for this routine to be called, the callout must
484 * have been active. Note that the callout is not deactivated until
485 * after the message has been processed in syncache_timer_handler() below.
488 syncache_timer(void *p)
490 struct netmsg_sc_timer *msg = p;
492 lwkt_sendmsg_oncpu(msg->nm_mrec->port, &msg->base.lmsg);
496 * Service a timer message queued by timer expiration.
497 * This routine runs in the TCP protocol thread.
499 * Walk the timer queues, looking for SYN,ACKs that need to be retransmitted.
500 * If we have retransmitted an entry the maximum number of times, expire it.
502 * When we finish processing timed-out entries, we restart the timer if there
503 * are any entries still on the queue and deactivate it otherwise. Only after
504 * a timer has been deactivated here can it be restarted by syncache_timeout().
507 syncache_timer_handler(netmsg_t msg)
509 struct tcp_syncache_percpu *syncache_percpu;
511 struct syncache marker;
512 struct syncache_list *list;
516 slot = ((struct netmsg_sc_timer *)msg)->nm_mrec->slot;
517 syncache_percpu = &tcp_syncache_percpu[mycpu->gd_cpuid];
519 list = &syncache_percpu->timerq[slot];
522 * Use a marker to keep our place in the scan. syncache_drop()
523 * can block and cause any next pointer we cache to become stale.
525 marker.sc_flags = SCF_MARKER;
526 TAILQ_INSERT_HEAD(list, &marker, sc_timerq);
528 while ((sc = TAILQ_NEXT(&marker, sc_timerq)) != NULL) {
532 TAILQ_REMOVE(list, &marker, sc_timerq);
533 TAILQ_INSERT_AFTER(list, sc, &marker, sc_timerq);
535 if (sc->sc_flags & SCF_MARKER)
538 if (ticks < sc->sc_rxttime)
539 break; /* finished because timerq sorted by time */
540 if (sc->sc_tp == NULL) {
541 syncache_drop(sc, NULL);
542 tcpstat.tcps_sc_stale++;
545 inp = sc->sc_tp->t_inpcb;
546 if (slot == SYNCACHE_MAXREXMTS ||
547 slot >= tcp_syncache.rexmt_limit ||
549 inp->inp_gencnt != sc->sc_inp_gencnt) {
550 syncache_drop(sc, NULL);
551 tcpstat.tcps_sc_stale++;
555 * syncache_respond() may call back into the syncache to
556 * to modify another entry, so do not obtain the next
557 * entry on the timer chain until it has completed.
559 syncache_respond(sc, NULL);
560 tcpstat.tcps_sc_retransmitted++;
561 TAILQ_REMOVE(list, sc, sc_timerq);
562 syncache_timeout(syncache_percpu, sc, slot + 1);
564 TAILQ_REMOVE(list, &marker, sc_timerq);
567 callout_reset(&syncache_percpu->tt_timerq[slot],
568 sc->sc_rxttime - ticks, syncache_timer,
569 &syncache_percpu->mrec[slot]);
571 callout_deactivate(&syncache_percpu->tt_timerq[slot]);
573 lwkt_replymsg(&msg->base.lmsg, 0);
577 * Find an entry in the syncache.
580 syncache_lookup(struct in_conninfo *inc, struct syncache_head **schp)
582 struct tcp_syncache_percpu *syncache_percpu;
584 struct syncache_head *sch;
586 syncache_percpu = &tcp_syncache_percpu[mycpu->gd_cpuid];
588 if (inc->inc_isipv6) {
589 sch = &syncache_percpu->hashbase[
590 SYNCACHE_HASH6(inc, tcp_syncache.hashmask)];
592 TAILQ_FOREACH(sc, &sch->sch_bucket, sc_hash)
593 if (ENDPTS6_EQ(&inc->inc_ie, &sc->sc_inc.inc_ie))
598 sch = &syncache_percpu->hashbase[
599 SYNCACHE_HASH(inc, tcp_syncache.hashmask)];
601 TAILQ_FOREACH(sc, &sch->sch_bucket, sc_hash) {
603 if (sc->sc_inc.inc_isipv6)
606 if (ENDPTS_EQ(&inc->inc_ie, &sc->sc_inc.inc_ie))
614 * This function is called when we get a RST for a
615 * non-existent connection, so that we can see if the
616 * connection is in the syn cache. If it is, zap it.
619 syncache_chkrst(struct in_conninfo *inc, struct tcphdr *th)
622 struct syncache_head *sch;
624 sc = syncache_lookup(inc, &sch);
629 * If the RST bit is set, check the sequence number to see
630 * if this is a valid reset segment.
632 * In all states except SYN-SENT, all reset (RST) segments
633 * are validated by checking their SEQ-fields. A reset is
634 * valid if its sequence number is in the window.
636 * The sequence number in the reset segment is normally an
637 * echo of our outgoing acknowlegement numbers, but some hosts
638 * send a reset with the sequence number at the rightmost edge
639 * of our receive window, and we have to handle this case.
641 if (SEQ_GEQ(th->th_seq, sc->sc_irs) &&
642 SEQ_LEQ(th->th_seq, sc->sc_irs + sc->sc_wnd)) {
643 syncache_drop(sc, sch);
644 tcpstat.tcps_sc_reset++;
649 syncache_badack(struct in_conninfo *inc)
652 struct syncache_head *sch;
654 sc = syncache_lookup(inc, &sch);
656 syncache_drop(sc, sch);
657 tcpstat.tcps_sc_badack++;
662 syncache_unreach(struct in_conninfo *inc, const struct tcphdr *th)
665 struct syncache_head *sch;
667 /* we are called at splnet() here */
668 sc = syncache_lookup(inc, &sch);
672 /* If the sequence number != sc_iss, then it's a bogus ICMP msg */
673 if (ntohl(th->th_seq) != sc->sc_iss)
677 * If we've rertransmitted 3 times and this is our second error,
678 * we remove the entry. Otherwise, we allow it to continue on.
679 * This prevents us from incorrectly nuking an entry during a
680 * spurious network outage.
684 if ((sc->sc_flags & SCF_UNREACH) == 0 || sc->sc_rxtslot < 3) {
685 sc->sc_flags |= SCF_UNREACH;
688 syncache_drop(sc, sch);
689 tcpstat.tcps_sc_unreach++;
693 * Build a new TCP socket structure from a syncache entry.
695 * This is called from the context of the SYN+ACK
697 static struct socket *
698 syncache_socket(struct syncache *sc, struct socket *lso, struct mbuf *m)
700 struct inpcb *inp = NULL, *linp;
702 struct tcpcb *tp, *ltp;
705 const boolean_t isipv6 = sc->sc_inc.inc_isipv6;
707 const boolean_t isipv6 = FALSE;
709 struct sockaddr_in sin_faddr;
710 struct sockaddr_in6 sin6_faddr;
711 struct sockaddr *faddr;
714 faddr = (struct sockaddr *)&sin6_faddr;
715 sin6_faddr.sin6_family = AF_INET6;
716 sin6_faddr.sin6_len = sizeof(sin6_faddr);
717 sin6_faddr.sin6_addr = sc->sc_inc.inc6_faddr;
718 sin6_faddr.sin6_port = sc->sc_inc.inc_fport;
719 sin6_faddr.sin6_flowinfo = sin6_faddr.sin6_scope_id = 0;
721 faddr = (struct sockaddr *)&sin_faddr;
722 sin_faddr.sin_family = AF_INET;
723 sin_faddr.sin_len = sizeof(sin_faddr);
724 sin_faddr.sin_addr = sc->sc_inc.inc_faddr;
725 sin_faddr.sin_port = sc->sc_inc.inc_fport;
726 bzero(sin_faddr.sin_zero, sizeof(sin_faddr.sin_zero));
730 * Ok, create the full blown connection, and set things up
731 * as they would have been set up if we had created the
732 * connection when the SYN arrived. If we can't create
733 * the connection, abort it.
735 * Set the protocol processing port for the socket to the current
736 * port (that the connection came in on).
739 * We don't keep a reference on the new socket, since its
740 * destruction will run in this thread (netisrN); there is no
743 so = sonewconn_faddr(lso, SS_ISCONNECTED, faddr,
744 FALSE /* don't ref */);
747 * Drop the connection; we will send a RST if the peer
748 * retransmits the ACK,
750 tcpstat.tcps_listendrop++;
755 * Insert new socket into hash list.
758 inp->inp_inc.inc_isipv6 = sc->sc_inc.inc_isipv6;
760 inp->in6p_laddr = sc->sc_inc.inc6_laddr;
762 KASSERT(INP_ISIPV4(inp), ("not inet pcb"));
763 inp->inp_laddr = sc->sc_inc.inc_laddr;
765 inp->inp_lport = sc->sc_inc.inc_lport;
766 in_pcbinsporthash_lport(inp);
770 /* copy old policy into new socket's */
771 if (ipsec_copy_policy(linp->inp_sp, inp->inp_sp))
772 kprintf("syncache_expand: could not copy policy\n");
775 struct in6_addr laddr6;
777 * Inherit socket options from the listening socket.
778 * Note that in6p_inputopts are not (and should not be)
779 * copied, since it stores previously received options and is
780 * used to detect if each new option is different than the
781 * previous one and hence should be passed to a user.
782 * If we copied in6p_inputopts, a user would not be able to
783 * receive options just after calling the accept system call.
785 inp->inp_flags |= linp->inp_flags & INP_CONTROLOPTS;
786 if (linp->in6p_outputopts)
787 inp->in6p_outputopts =
788 ip6_copypktopts(linp->in6p_outputopts, M_INTWAIT);
789 inp->in6p_route = sc->sc_route6;
790 sc->sc_route6.ro_rt = NULL;
792 laddr6 = inp->in6p_laddr;
793 if (IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_laddr))
794 inp->in6p_laddr = sc->sc_inc.inc6_laddr;
795 if (in6_pcbconnect(inp, faddr, &thread0)) {
796 inp->in6p_laddr = laddr6;
800 struct in_addr laddr;
802 inp->inp_options = ip_srcroute(m);
803 if (inp->inp_options == NULL) {
804 inp->inp_options = sc->sc_ipopts;
805 sc->sc_ipopts = NULL;
807 inp->inp_route = sc->sc_route;
808 sc->sc_route.ro_rt = NULL;
810 laddr = inp->inp_laddr;
811 if (inp->inp_laddr.s_addr == INADDR_ANY)
812 inp->inp_laddr = sc->sc_inc.inc_laddr;
813 if (in_pcbconnect(inp, faddr, &thread0)) {
814 inp->inp_laddr = laddr;
820 * The current port should be in the context of the SYN+ACK and
821 * so should match the tcp address port.
824 port = tcp6_addrport();
826 port = tcp_addrport(inp->inp_faddr.s_addr, inp->inp_fport,
827 inp->inp_laddr.s_addr, inp->inp_lport);
829 KASSERT(port == &curthread->td_msgport,
830 ("TCP PORT MISMATCH %p vs %p\n", port, &curthread->td_msgport));
833 tp->t_state = TCPS_SYN_RECEIVED;
834 tp->iss = sc->sc_iss;
835 tp->irs = sc->sc_irs;
838 tp->snd_wnd = sc->sc_sndwnd;
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;
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->snd_scale = sc->sc_requested_s_scale;
850 tp->request_r_scale = sc->sc_request_r_scale;
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;
857 if (sc->sc_flags & SCF_SACK_PERMITTED)
858 tp->t_flags |= TF_SACK_PERMITTED;
861 if (sc->sc_flags & SCF_SIGNATURE)
862 tp->t_flags |= TF_SIGNATURE;
863 #endif /* TCP_SIGNATURE */
865 tp->t_rxtsyn = sc->sc_rxtused;
866 tcp_mss(tp, sc->sc_peer_mss);
869 * Inherit some properties from the listen socket
871 ltp = intotcpcb(linp);
872 tp->t_keepinit = ltp->t_keepinit;
873 tp->t_keepidle = ltp->t_keepidle;
874 tp->t_keepintvl = ltp->t_keepintvl;
875 tp->t_keepcnt = ltp->t_keepcnt;
876 tp->t_maxidle = ltp->t_maxidle;
878 tcp_create_timermsg(tp, port);
879 tcp_callout_reset(tp, tp->tt_keep, tp->t_keepinit, tcp_timer_keep);
881 tcpstat.tcps_accepts++;
891 * This function gets called when we receive an ACK for a
892 * socket in the LISTEN state. We look up the connection
893 * in the syncache, and if its there, we pull it out of
894 * the cache and turn it into a full-blown connection in
895 * the SYN-RECEIVED state.
898 syncache_expand(struct in_conninfo *inc, struct tcphdr *th, struct socket **sop,
902 struct syncache_head *sch;
905 sc = syncache_lookup(inc, &sch);
908 * There is no syncache entry, so see if this ACK is
909 * a returning syncookie. To do this, first:
910 * A. See if this socket has had a syncache entry dropped in
911 * the past. We don't want to accept a bogus syncookie
912 * if we've never received a SYN.
913 * B. check that the syncookie is valid. If it is, then
914 * cobble up a fake syncache entry, and return.
918 sc = syncookie_lookup(inc, th, *sop);
922 tcpstat.tcps_sc_recvcookie++;
926 * If seg contains an ACK, but not for our SYN/ACK, send a RST.
928 if (th->th_ack != sc->sc_iss + 1)
931 so = syncache_socket(sc, *sop, m);
935 /* XXXjlemon check this - is this correct? */
936 tcp_respond(NULL, m, m, th,
937 th->th_seq + tlen, (tcp_seq)0, TH_RST | TH_ACK);
939 m_freem(m); /* XXX only needed for above */
940 tcpstat.tcps_sc_aborted++;
942 tcpstat.tcps_sc_completed++;
947 syncache_drop(sc, sch);
953 * Given a LISTEN socket and an inbound SYN request, add
954 * this to the syn cache, and send back a segment:
955 * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK>
958 * IMPORTANT NOTE: We do _NOT_ ACK data that might accompany the SYN.
959 * Doing so would require that we hold onto the data and deliver it
960 * to the application. However, if we are the target of a SYN-flood
961 * DoS attack, an attacker could send data which would eventually
962 * consume all available buffer space if it were ACKed. By not ACKing
963 * the data, we avoid this DoS scenario.
966 syncache_add(struct in_conninfo *inc, struct tcpopt *to, struct tcphdr *th,
967 struct socket *so, struct mbuf *m)
969 struct tcp_syncache_percpu *syncache_percpu;
971 struct syncache *sc = NULL;
972 struct syncache_head *sch;
973 struct mbuf *ipopts = NULL;
976 syncache_percpu = &tcp_syncache_percpu[mycpu->gd_cpuid];
980 * Remember the IP options, if any.
983 if (!inc->inc_isipv6)
985 ipopts = ip_srcroute(m);
988 * See if we already have an entry for this connection.
989 * If we do, resend the SYN,ACK, and reset the retransmit timer.
992 * The syncache should be re-initialized with the contents
993 * of the new SYN which may have different options.
995 sc = syncache_lookup(inc, &sch);
997 tcpstat.tcps_sc_dupsyn++;
1000 * If we were remembering a previous source route,
1001 * forget it and use the new one we've been given.
1004 m_free(sc->sc_ipopts);
1005 sc->sc_ipopts = ipopts;
1008 * Update timestamp if present.
1010 if (sc->sc_flags & SCF_TIMESTAMP)
1011 sc->sc_tsrecent = to->to_tsval;
1013 /* Just update the TOF_SACK_PERMITTED for now. */
1014 if (tcp_do_sack && (to->to_flags & TOF_SACK_PERMITTED))
1015 sc->sc_flags |= SCF_SACK_PERMITTED;
1017 sc->sc_flags &= ~SCF_SACK_PERMITTED;
1019 /* Update initial send window */
1020 sc->sc_sndwnd = th->th_win;
1023 * PCB may have changed, pick up new values.
1026 sc->sc_inp_gencnt = tp->t_inpcb->inp_gencnt;
1027 if (syncache_respond(sc, m) == 0) {
1028 TAILQ_REMOVE(&syncache_percpu->timerq[sc->sc_rxtslot],
1030 syncache_timeout(syncache_percpu, sc, sc->sc_rxtslot);
1031 tcpstat.tcps_sndacks++;
1032 tcpstat.tcps_sndtotal++;
1038 * Fill in the syncache values.
1040 sc = kmalloc(sizeof(struct syncache), M_SYNCACHE, M_WAITOK|M_ZERO);
1041 sc->sc_inp_gencnt = tp->t_inpcb->inp_gencnt;
1042 sc->sc_ipopts = ipopts;
1043 sc->sc_inc.inc_fport = inc->inc_fport;
1044 sc->sc_inc.inc_lport = inc->inc_lport;
1047 sc->sc_inc.inc_isipv6 = inc->inc_isipv6;
1048 if (inc->inc_isipv6) {
1049 sc->sc_inc.inc6_faddr = inc->inc6_faddr;
1050 sc->sc_inc.inc6_laddr = inc->inc6_laddr;
1051 sc->sc_route6.ro_rt = NULL;
1055 sc->sc_inc.inc_faddr = inc->inc_faddr;
1056 sc->sc_inc.inc_laddr = inc->inc_laddr;
1057 sc->sc_route.ro_rt = NULL;
1059 sc->sc_irs = th->th_seq;
1061 sc->sc_peer_mss = to->to_flags & TOF_MSS ? to->to_mss : 0;
1063 sc->sc_iss = syncookie_generate(sc);
1065 sc->sc_iss = karc4random();
1067 /* Initial receive window: clip ssb_space to [0 .. TCP_MAXWIN] */
1068 win = ssb_space(&so->so_rcv);
1070 win = imin(win, TCP_MAXWIN);
1073 if (tcp_do_rfc1323) {
1075 * A timestamp received in a SYN makes
1076 * it ok to send timestamp requests and replies.
1078 if (to->to_flags & TOF_TS) {
1079 sc->sc_tsrecent = to->to_tsval;
1080 sc->sc_flags |= SCF_TIMESTAMP;
1082 if (to->to_flags & TOF_SCALE) {
1083 int wscale = TCP_MIN_WINSHIFT;
1085 /* Compute proper scaling value from buffer space */
1086 while (wscale < TCP_MAX_WINSHIFT &&
1087 (TCP_MAXWIN << wscale) < so->so_rcv.ssb_hiwat) {
1090 sc->sc_request_r_scale = wscale;
1091 sc->sc_requested_s_scale = to->to_requested_s_scale;
1092 sc->sc_flags |= SCF_WINSCALE;
1095 if (tcp_do_sack && (to->to_flags & TOF_SACK_PERMITTED))
1096 sc->sc_flags |= SCF_SACK_PERMITTED;
1097 if (tp->t_flags & TF_NOOPT)
1098 sc->sc_flags = SCF_NOOPT;
1099 #ifdef TCP_SIGNATURE
1101 * If listening socket requested TCP digests, and received SYN
1102 * contains the option, flag this in the syncache so that
1103 * syncache_respond() will do the right thing with the SYN+ACK.
1104 * XXX Currently we always record the option by default and will
1105 * attempt to use it in syncache_respond().
1107 if (to->to_flags & TOF_SIGNATURE)
1108 sc->sc_flags = SCF_SIGNATURE;
1109 #endif /* TCP_SIGNATURE */
1110 sc->sc_sndwnd = th->th_win;
1112 if (syncache_respond(sc, m) == 0) {
1113 syncache_insert(sc, sch);
1114 tcpstat.tcps_sndacks++;
1115 tcpstat.tcps_sndtotal++;
1118 tcpstat.tcps_sc_dropped++;
1124 syncache_respond(struct syncache *sc, struct mbuf *m)
1128 u_int16_t tlen, hlen, mssopt;
1129 struct ip *ip = NULL;
1132 struct ip6_hdr *ip6 = NULL;
1134 const boolean_t isipv6 = sc->sc_inc.inc_isipv6;
1136 const boolean_t isipv6 = FALSE;
1140 rt = tcp_rtlookup6(&sc->sc_inc);
1142 mssopt = rt->rt_ifp->if_mtu -
1143 (sizeof(struct ip6_hdr) + sizeof(struct tcphdr));
1145 mssopt = tcp_v6mssdflt;
1146 hlen = sizeof(struct ip6_hdr);
1148 rt = tcp_rtlookup(&sc->sc_inc);
1150 mssopt = rt->rt_ifp->if_mtu -
1151 (sizeof(struct ip) + sizeof(struct tcphdr));
1153 mssopt = tcp_mssdflt;
1154 hlen = sizeof(struct ip);
1157 /* Compute the size of the TCP options. */
1158 if (sc->sc_flags & SCF_NOOPT) {
1161 optlen = TCPOLEN_MAXSEG +
1162 ((sc->sc_flags & SCF_WINSCALE) ? 4 : 0) +
1163 ((sc->sc_flags & SCF_TIMESTAMP) ? TCPOLEN_TSTAMP_APPA : 0) +
1164 ((sc->sc_flags & SCF_SACK_PERMITTED) ?
1165 TCPOLEN_SACK_PERMITTED_ALIGNED : 0);
1166 #ifdef TCP_SIGNATURE
1167 optlen += ((sc->sc_flags & SCF_SIGNATURE) ?
1168 (TCPOLEN_SIGNATURE + 2) : 0);
1169 #endif /* TCP_SIGNATURE */
1171 tlen = hlen + sizeof(struct tcphdr) + optlen;
1175 * assume that the entire packet will fit in a header mbuf
1177 KASSERT(max_linkhdr + tlen <= MHLEN, ("syncache: mbuf too small"));
1180 * XXX shouldn't this reuse the mbuf if possible ?
1181 * Create the IP+TCP header from scratch.
1186 m = m_gethdr(M_NOWAIT, MT_HEADER);
1189 m->m_data += max_linkhdr;
1191 m->m_pkthdr.len = tlen;
1192 m->m_pkthdr.rcvif = NULL;
1193 if (tcp_prio_synack)
1194 m->m_flags |= M_PRIO;
1197 ip6 = mtod(m, struct ip6_hdr *);
1198 ip6->ip6_vfc = IPV6_VERSION;
1199 ip6->ip6_nxt = IPPROTO_TCP;
1200 ip6->ip6_src = sc->sc_inc.inc6_laddr;
1201 ip6->ip6_dst = sc->sc_inc.inc6_faddr;
1202 ip6->ip6_plen = htons(tlen - hlen);
1203 /* ip6_hlim is set after checksum */
1204 /* ip6_flow = ??? */
1206 th = (struct tcphdr *)(ip6 + 1);
1208 ip = mtod(m, struct ip *);
1209 ip->ip_v = IPVERSION;
1210 ip->ip_hl = sizeof(struct ip) >> 2;
1215 ip->ip_p = IPPROTO_TCP;
1216 ip->ip_src = sc->sc_inc.inc_laddr;
1217 ip->ip_dst = sc->sc_inc.inc_faddr;
1218 ip->ip_ttl = sc->sc_tp->t_inpcb->inp_ip_ttl; /* XXX */
1219 ip->ip_tos = sc->sc_tp->t_inpcb->inp_ip_tos; /* XXX */
1222 * See if we should do MTU discovery. Route lookups are
1223 * expensive, so we will only unset the DF bit if:
1225 * 1) path_mtu_discovery is disabled
1226 * 2) the SCF_UNREACH flag has been set
1228 if (path_mtu_discovery
1229 && ((sc->sc_flags & SCF_UNREACH) == 0)) {
1230 ip->ip_off |= IP_DF;
1233 th = (struct tcphdr *)(ip + 1);
1235 th->th_sport = sc->sc_inc.inc_lport;
1236 th->th_dport = sc->sc_inc.inc_fport;
1238 th->th_seq = htonl(sc->sc_iss);
1239 th->th_ack = htonl(sc->sc_irs + 1);
1240 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2;
1242 th->th_flags = TH_SYN | TH_ACK;
1243 th->th_win = htons(sc->sc_wnd);
1246 /* Tack on the TCP options. */
1249 optp = (u_int8_t *)(th + 1);
1250 *optp++ = TCPOPT_MAXSEG;
1251 *optp++ = TCPOLEN_MAXSEG;
1252 *optp++ = (mssopt >> 8) & 0xff;
1253 *optp++ = mssopt & 0xff;
1255 if (sc->sc_flags & SCF_WINSCALE) {
1256 *((u_int32_t *)optp) = htonl(TCPOPT_NOP << 24 |
1257 TCPOPT_WINDOW << 16 | TCPOLEN_WINDOW << 8 |
1258 sc->sc_request_r_scale);
1262 if (sc->sc_flags & SCF_TIMESTAMP) {
1263 u_int32_t *lp = (u_int32_t *)(optp);
1265 /* Form timestamp option as shown in appendix A of RFC 1323. */
1266 *lp++ = htonl(TCPOPT_TSTAMP_HDR);
1267 *lp++ = htonl(ticks);
1268 *lp = htonl(sc->sc_tsrecent);
1269 optp += TCPOLEN_TSTAMP_APPA;
1272 #ifdef TCP_SIGNATURE
1274 * Handle TCP-MD5 passive opener response.
1276 if (sc->sc_flags & SCF_SIGNATURE) {
1277 u_int8_t *bp = optp;
1280 *bp++ = TCPOPT_SIGNATURE;
1281 *bp++ = TCPOLEN_SIGNATURE;
1282 for (i = 0; i < TCP_SIGLEN; i++)
1284 tcpsignature_compute(m, 0, optlen,
1285 optp + 2, IPSEC_DIR_OUTBOUND);
1288 optp += TCPOLEN_SIGNATURE + 2;
1290 #endif /* TCP_SIGNATURE */
1292 if (sc->sc_flags & SCF_SACK_PERMITTED) {
1293 *((u_int32_t *)optp) = htonl(TCPOPT_SACK_PERMITTED_ALIGNED);
1294 optp += TCPOLEN_SACK_PERMITTED_ALIGNED;
1299 struct route_in6 *ro6 = &sc->sc_route6;
1302 th->th_sum = in6_cksum(m, IPPROTO_TCP, hlen, tlen - hlen);
1303 ip6->ip6_hlim = in6_selecthlim(NULL,
1304 ro6->ro_rt ? ro6->ro_rt->rt_ifp : NULL);
1305 error = ip6_output(m, NULL, ro6, 0, NULL, NULL,
1306 sc->sc_tp->t_inpcb);
1308 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
1309 htons(tlen - hlen + IPPROTO_TCP));
1310 m->m_pkthdr.csum_flags = CSUM_TCP;
1311 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
1312 m->m_pkthdr.csum_thlen = sizeof(struct tcphdr) + optlen;
1313 error = ip_output(m, sc->sc_ipopts, &sc->sc_route,
1314 IP_DEBUGROUTE, NULL, sc->sc_tp->t_inpcb);
1322 * |. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .|
1324 * | MD5(laddr,faddr,secret,lport,fport) |. . . . . . .|
1326 * (A): peer mss index
1330 * The values below are chosen to minimize the size of the tcp_secret
1331 * table, as well as providing roughly a 16 second lifetime for the cookie.
1334 #define SYNCOOKIE_WNDBITS 5 /* exposed bits for window indexing */
1335 #define SYNCOOKIE_TIMESHIFT 1 /* scale ticks to window time units */
1337 #define SYNCOOKIE_WNDMASK ((1 << SYNCOOKIE_WNDBITS) - 1)
1338 #define SYNCOOKIE_NSECRETS (1 << SYNCOOKIE_WNDBITS)
1339 #define SYNCOOKIE_TIMEOUT \
1340 (hz * (1 << SYNCOOKIE_WNDBITS) / (1 << SYNCOOKIE_TIMESHIFT))
1341 #define SYNCOOKIE_DATAMASK ((3 << SYNCOOKIE_WNDBITS) | SYNCOOKIE_WNDMASK)
1344 u_int32_t ts_secbits[4];
1346 } tcp_secret[SYNCOOKIE_NSECRETS];
1348 static int tcp_msstab[] = { 0, 536, 1460, 8960 };
1350 static MD5_CTX syn_ctx;
1352 #define MD5Add(v) MD5Update(&syn_ctx, (u_char *)&v, sizeof(v))
1355 u_int32_t laddr, faddr;
1356 u_int32_t secbits[4];
1357 u_int16_t lport, fport;
1361 CTASSERT(sizeof(struct md5_add) == 28);
1365 * Consider the problem of a recreated (and retransmitted) cookie. If the
1366 * original SYN was accepted, the connection is established. The second
1367 * SYN is inflight, and if it arrives with an ISN that falls within the
1368 * receive window, the connection is killed.
1370 * However, since cookies have other problems, this may not be worth
1375 syncookie_generate(struct syncache *sc)
1377 u_int32_t md5_buffer[4];
1382 const boolean_t isipv6 = sc->sc_inc.inc_isipv6;
1384 const boolean_t isipv6 = FALSE;
1387 idx = ((ticks << SYNCOOKIE_TIMESHIFT) / hz) & SYNCOOKIE_WNDMASK;
1388 if (tcp_secret[idx].ts_expire < ticks) {
1389 for (i = 0; i < 4; i++)
1390 tcp_secret[idx].ts_secbits[i] = karc4random();
1391 tcp_secret[idx].ts_expire = ticks + SYNCOOKIE_TIMEOUT;
1393 for (data = NELEM(tcp_msstab) - 1; data > 0; data--)
1394 if (tcp_msstab[data] <= sc->sc_peer_mss)
1396 data = (data << SYNCOOKIE_WNDBITS) | idx;
1397 data ^= sc->sc_irs; /* peer's iss */
1400 MD5Add(sc->sc_inc.inc6_laddr);
1401 MD5Add(sc->sc_inc.inc6_faddr);
1405 add.laddr = sc->sc_inc.inc_laddr.s_addr;
1406 add.faddr = sc->sc_inc.inc_faddr.s_addr;
1408 add.lport = sc->sc_inc.inc_lport;
1409 add.fport = sc->sc_inc.inc_fport;
1410 add.secbits[0] = tcp_secret[idx].ts_secbits[0];
1411 add.secbits[1] = tcp_secret[idx].ts_secbits[1];
1412 add.secbits[2] = tcp_secret[idx].ts_secbits[2];
1413 add.secbits[3] = tcp_secret[idx].ts_secbits[3];
1415 MD5Final((u_char *)&md5_buffer, &syn_ctx);
1416 data ^= (md5_buffer[0] & ~SYNCOOKIE_WNDMASK);
1420 static struct syncache *
1421 syncookie_lookup(struct in_conninfo *inc, struct tcphdr *th, struct socket *so)
1423 u_int32_t md5_buffer[4];
1424 struct syncache *sc;
1429 data = (th->th_ack - 1) ^ (th->th_seq - 1); /* remove ISS */
1430 idx = data & SYNCOOKIE_WNDMASK;
1431 if (tcp_secret[idx].ts_expire < ticks ||
1432 sototcpcb(so)->ts_recent + SYNCOOKIE_TIMEOUT < ticks)
1436 if (inc->inc_isipv6) {
1437 MD5Add(inc->inc6_laddr);
1438 MD5Add(inc->inc6_faddr);
1444 add.laddr = inc->inc_laddr.s_addr;
1445 add.faddr = inc->inc_faddr.s_addr;
1447 add.lport = inc->inc_lport;
1448 add.fport = inc->inc_fport;
1449 add.secbits[0] = tcp_secret[idx].ts_secbits[0];
1450 add.secbits[1] = tcp_secret[idx].ts_secbits[1];
1451 add.secbits[2] = tcp_secret[idx].ts_secbits[2];
1452 add.secbits[3] = tcp_secret[idx].ts_secbits[3];
1454 MD5Final((u_char *)&md5_buffer, &syn_ctx);
1455 data ^= md5_buffer[0];
1456 if (data & ~SYNCOOKIE_DATAMASK)
1458 data = data >> SYNCOOKIE_WNDBITS;
1461 * Fill in the syncache values.
1462 * XXX duplicate code from syncache_add
1464 sc = kmalloc(sizeof(struct syncache), M_SYNCACHE, M_WAITOK|M_ZERO);
1465 sc->sc_ipopts = NULL;
1466 sc->sc_inc.inc_fport = inc->inc_fport;
1467 sc->sc_inc.inc_lport = inc->inc_lport;
1469 sc->sc_inc.inc_isipv6 = inc->inc_isipv6;
1470 if (inc->inc_isipv6) {
1471 sc->sc_inc.inc6_faddr = inc->inc6_faddr;
1472 sc->sc_inc.inc6_laddr = inc->inc6_laddr;
1473 sc->sc_route6.ro_rt = NULL;
1477 sc->sc_inc.inc_faddr = inc->inc_faddr;
1478 sc->sc_inc.inc_laddr = inc->inc_laddr;
1479 sc->sc_route.ro_rt = NULL;
1481 sc->sc_irs = th->th_seq - 1;
1482 sc->sc_iss = th->th_ack - 1;
1483 wnd = ssb_space(&so->so_rcv);
1485 wnd = imin(wnd, TCP_MAXWIN);
1489 sc->sc_peer_mss = tcp_msstab[data];