<signal.h> has to and does provide pid_t, so we can also use it.
[dragonfly.git] / sys / netinet / tcp_syncache.c
blob52894ae2312a512e4c9b3b5ae086861906d7422b
1 /*
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
6 * by Jeffrey M. Hsu.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of The DragonFly Project nor the names of its
17 * contributors may be used to endorse or promote products derived
18 * from this software without specific, prior written permission.
20 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
22 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
23 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
24 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
25 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
26 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
27 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
28 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
29 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
30 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
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
49 * are met:
50 * 1. Redistributions of source code must retain the above copyright
51 * notice, this list of conditions and the following disclaimer.
52 * 2. Redistributions in binary form must reproduce the above copyright
53 * notice, this list of conditions and the following disclaimer in the
54 * documentation and/or other materials provided with the distribution.
55 * 3. The name of the author may not be used to endorse or promote
56 * products derived from this software without specific prior written
57 * permission.
59 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
60 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
61 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
62 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
63 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
64 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
65 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
66 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
67 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
68 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
69 * SUCH DAMAGE.
71 * $FreeBSD: src/sys/netinet/tcp_syncache.c,v 1.5.2.14 2003/02/24 04:02:27 silby Exp $
74 #include "opt_inet.h"
75 #include "opt_inet6.h"
77 #include <sys/param.h>
78 #include <sys/systm.h>
79 #include <sys/kernel.h>
80 #include <sys/sysctl.h>
81 #include <sys/malloc.h>
82 #include <sys/mbuf.h>
83 #include <sys/md5.h>
84 #include <sys/proc.h> /* for proc0 declaration */
85 #include <sys/random.h>
86 #include <sys/socket.h>
87 #include <sys/socketvar.h>
88 #include <sys/in_cksum.h>
90 #include <sys/msgport2.h>
91 #include <net/netmsg2.h>
92 #include <net/netisr2.h>
94 #include <net/if.h>
95 #include <net/route.h>
97 #include <netinet/in.h>
98 #include <netinet/in_systm.h>
99 #include <netinet/ip.h>
100 #include <netinet/in_var.h>
101 #include <netinet/in_pcb.h>
102 #include <netinet/ip_var.h>
103 #include <netinet/ip6.h>
104 #ifdef INET6
105 #include <netinet/icmp6.h>
106 #include <netinet6/nd6.h>
107 #endif
108 #include <netinet6/ip6_var.h>
109 #include <netinet6/in6_pcb.h>
110 #include <netinet/tcp.h>
111 #include <netinet/tcp_fsm.h>
112 #include <netinet/tcp_seq.h>
113 #include <netinet/tcp_timer.h>
114 #include <netinet/tcp_timer2.h>
115 #include <netinet/tcp_var.h>
116 #include <netinet6/tcp6_var.h>
118 static int tcp_syncookies = 1;
119 SYSCTL_INT(_net_inet_tcp, OID_AUTO, syncookies, CTLFLAG_RW,
120 &tcp_syncookies, 0,
121 "Use TCP SYN cookies if the syncache overflows");
123 static void syncache_drop(struct syncache *, struct syncache_head *);
124 static void syncache_free(struct syncache *);
125 static void syncache_insert(struct syncache *, struct syncache_head *);
126 static struct syncache *syncache_lookup(struct in_conninfo *,
127 struct syncache_head **);
128 static int syncache_respond(struct syncache *, struct mbuf *);
129 static struct socket *syncache_socket(struct syncache *, struct socket *,
130 struct mbuf *);
131 static void syncache_timer(void *);
132 static u_int32_t syncookie_generate(struct syncache *);
133 static struct syncache *syncookie_lookup(struct in_conninfo *,
134 struct tcphdr *, struct socket *);
137 * Transmit the SYN,ACK fewer times than TCP_MAXRXTSHIFT specifies.
138 * 4 retransmits corresponds to a timeout of (3 + 3 + 3 + 3 + 3 == 15) seconds
139 * or (1 + 1 + 2 + 4 + 8 == 16) seconds if RFC6298 is used, the odds are that
140 * the user has given up attempting to connect by then.
142 #define SYNCACHE_MAXREXMTS 4
144 /* Arbitrary values */
145 #define TCP_SYNCACHE_HASHSIZE 512
146 #define TCP_SYNCACHE_BUCKETLIMIT 30
148 static void syncache_timer_handler(netmsg_t);
149 static int syncache_sysctl_count(SYSCTL_HANDLER_ARGS);
151 struct tcp_syncache {
152 u_int hashsize;
153 u_int hashmask;
154 u_int bucket_limit;
155 u_int cache_limit;
156 u_int rexmt_limit;
157 u_int hash_secret;
159 static struct tcp_syncache tcp_syncache;
161 struct syncache_timerq {
162 TAILQ_HEAD(, syncache) list;
163 struct callout timeo;
164 struct netmsg_base nm;
167 struct tcp_syncache_percpu {
168 struct syncache_head *hashbase;
169 u_int cache_count;
170 struct syncache_timerq timerq[SYNCACHE_MAXREXMTS + 1];
173 static struct tcp_syncache_percpu *tcp_syncache_percpu[MAXCPU];
175 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, syncache, CTLFLAG_RW, 0, "TCP SYN cache");
177 SYSCTL_INT(_net_inet_tcp_syncache, OID_AUTO, bucketlimit, CTLFLAG_RD,
178 &tcp_syncache.bucket_limit, 0, "Per-bucket hash limit for syncache");
180 SYSCTL_INT(_net_inet_tcp_syncache, OID_AUTO, cachelimit, CTLFLAG_RD,
181 &tcp_syncache.cache_limit, 0, "Overall entry limit for syncache");
183 SYSCTL_PROC(_net_inet_tcp_syncache, OID_AUTO, count, (CTLTYPE_INT | CTLFLAG_RD),
184 0, 0, syncache_sysctl_count, "I", "Current number of entries in syncache");
186 SYSCTL_INT(_net_inet_tcp_syncache, OID_AUTO, hashsize, CTLFLAG_RD,
187 &tcp_syncache.hashsize, 0, "Size of TCP syncache hashtable");
189 SYSCTL_INT(_net_inet_tcp_syncache, OID_AUTO, rexmtlimit, CTLFLAG_RW,
190 &tcp_syncache.rexmt_limit, 0, "Limit on SYN/ACK retransmissions");
192 static MALLOC_DEFINE(M_SYNCACHE, "syncache", "TCP syncache");
194 #define SYNCACHE_HASH(inc, mask) \
195 ((tcp_syncache.hash_secret ^ \
196 (inc)->inc_faddr.s_addr ^ \
197 ((inc)->inc_faddr.s_addr >> 16) ^ \
198 (inc)->inc_fport ^ (inc)->inc_lport) & mask)
200 #define SYNCACHE_HASH6(inc, mask) \
201 ((tcp_syncache.hash_secret ^ \
202 (inc)->inc6_faddr.s6_addr32[0] ^ \
203 (inc)->inc6_faddr.s6_addr32[3] ^ \
204 (inc)->inc_fport ^ (inc)->inc_lport) & mask)
206 #define ENDPTS_EQ(a, b) ( \
207 (a)->ie_fport == (b)->ie_fport && \
208 (a)->ie_lport == (b)->ie_lport && \
209 (a)->ie_faddr.s_addr == (b)->ie_faddr.s_addr && \
210 (a)->ie_laddr.s_addr == (b)->ie_laddr.s_addr \
213 #define ENDPTS6_EQ(a, b) (memcmp(a, b, sizeof(*a)) == 0)
215 static __inline int
216 syncache_rto(int slot)
218 if (tcp_low_rtobase)
219 return (TCPTV_RTOBASE * tcp_syn_backoff_low[slot]);
220 else
221 return (TCPTV_RTOBASE * tcp_syn_backoff[slot]);
224 static __inline void
225 syncache_timeout(struct tcp_syncache_percpu *syncache_percpu,
226 struct syncache *sc, int slot)
228 struct syncache_timerq *tq;
229 int rto;
231 KASSERT(slot <= SYNCACHE_MAXREXMTS,
232 ("syncache: invalid slot %d", slot));
234 if (slot > 0) {
236 * Record the time that we spent in SYN|ACK
237 * retransmition.
239 * Needed by RFC3390 and RFC6298.
241 sc->sc_rxtused += syncache_rto(slot - 1);
243 sc->sc_rxtslot = slot;
245 rto = syncache_rto(slot);
246 sc->sc_rxttime = ticks + rto;
248 tq = &syncache_percpu->timerq[slot];
249 TAILQ_INSERT_TAIL(&tq->list, sc, sc_timerq);
250 if (!callout_active(&tq->timeo))
251 callout_reset(&tq->timeo, rto, syncache_timer, &tq->nm);
254 static void
255 syncache_free(struct syncache *sc)
257 struct rtentry *rt;
258 #ifdef INET6
259 const boolean_t isipv6 = sc->sc_inc.inc_isipv6;
260 #else
261 const boolean_t isipv6 = FALSE;
262 #endif
264 if (sc->sc_ipopts)
265 m_free(sc->sc_ipopts);
267 rt = isipv6 ? sc->sc_route6.ro_rt : sc->sc_route.ro_rt;
268 if (rt != NULL) {
270 * If this is the only reference to a protocol-cloned
271 * route, remove it immediately.
273 if ((rt->rt_flags & (RTF_WASCLONED | RTF_LLINFO)) ==
274 RTF_WASCLONED && rt->rt_refcnt == 1) {
275 rtrequest(RTM_DELETE, rt_key(rt), rt->rt_gateway,
276 rt_mask(rt), rt->rt_flags, NULL);
278 RTFREE(rt);
280 kfree(sc, M_SYNCACHE);
283 static void
284 syncache_init_dispatch(netmsg_t nm)
286 struct tcp_syncache_percpu *syncache_percpu;
287 int i;
289 ASSERT_NETISR_NCPUS(mycpuid);
291 syncache_percpu = kmalloc(sizeof(*syncache_percpu), M_SYNCACHE,
292 M_WAITOK | M_ZERO);
294 /* Allocate the hash table. */
295 syncache_percpu->hashbase = kmalloc(tcp_syncache.hashsize *
296 sizeof(struct syncache_head),
297 M_SYNCACHE, M_WAITOK | M_ZERO);
299 /* Initialize the hash buckets. */
300 for (i = 0; i < tcp_syncache.hashsize; i++) {
301 struct syncache_head *bucket;
303 bucket = &syncache_percpu->hashbase[i];
304 TAILQ_INIT(&bucket->sch_bucket);
305 bucket->sch_length = 0;
308 for (i = 0; i <= SYNCACHE_MAXREXMTS; i++) {
309 struct syncache_timerq *tq =
310 &syncache_percpu->timerq[i];
312 /* Initialize the timer queues. */
313 TAILQ_INIT(&tq->list);
314 callout_init_mp(&tq->timeo);
316 netmsg_init(&tq->nm, NULL, &netisr_adone_rport,
317 MSGF_PRIORITY, syncache_timer_handler);
318 tq->nm.lmsg.u.ms_result = i;
321 tcp_syncache_percpu[mycpuid] = syncache_percpu;
323 netisr_forwardmsg(&nm->base, mycpuid + 1);
326 void
327 syncache_init(void)
329 struct netmsg_base nm;
331 tcp_syncache.hashsize = TCP_SYNCACHE_HASHSIZE;
332 tcp_syncache.bucket_limit = TCP_SYNCACHE_BUCKETLIMIT;
333 tcp_syncache.cache_limit =
334 tcp_syncache.hashsize * tcp_syncache.bucket_limit;
335 tcp_syncache.rexmt_limit = SYNCACHE_MAXREXMTS;
336 tcp_syncache.hash_secret = karc4random();
338 TUNABLE_INT_FETCH("net.inet.tcp.syncache.hashsize",
339 &tcp_syncache.hashsize);
340 TUNABLE_INT_FETCH("net.inet.tcp.syncache.cachelimit",
341 &tcp_syncache.cache_limit);
342 TUNABLE_INT_FETCH("net.inet.tcp.syncache.bucketlimit",
343 &tcp_syncache.bucket_limit);
344 if (!powerof2(tcp_syncache.hashsize)) {
345 kprintf("WARNING: syncache hash size is not a power of 2.\n");
346 tcp_syncache.hashsize = 512; /* safe default */
348 tcp_syncache.hashmask = tcp_syncache.hashsize - 1;
350 netmsg_init(&nm, NULL, &curthread->td_msgport, 0,
351 syncache_init_dispatch);
352 netisr_domsg_global(&nm);
355 static void
356 syncache_insert(struct syncache *sc, struct syncache_head *sch)
358 struct tcp_syncache_percpu *syncache_percpu;
359 struct syncache *sc2;
360 int i;
362 syncache_percpu = tcp_syncache_percpu[mycpu->gd_cpuid];
365 * Make sure that we don't overflow the per-bucket
366 * limit or the total cache size limit.
368 if (sch->sch_length >= tcp_syncache.bucket_limit) {
370 * The bucket is full, toss the oldest element.
372 sc2 = TAILQ_FIRST(&sch->sch_bucket);
373 if (sc2->sc_tp != NULL)
374 sc2->sc_tp->ts_recent = ticks;
375 syncache_drop(sc2, sch);
376 tcpstat.tcps_sc_bucketoverflow++;
377 } else if (syncache_percpu->cache_count >= tcp_syncache.cache_limit) {
379 * The cache is full. Toss the oldest entry in the
380 * entire cache. This is the front entry in the
381 * first non-empty timer queue with the largest
382 * timeout value.
384 for (i = SYNCACHE_MAXREXMTS; i >= 0; i--) {
385 sc2 = TAILQ_FIRST(&syncache_percpu->timerq[i].list);
386 if (sc2 != NULL)
387 break;
389 if (sc2->sc_tp != NULL)
390 sc2->sc_tp->ts_recent = ticks;
391 syncache_drop(sc2, NULL);
392 tcpstat.tcps_sc_cacheoverflow++;
395 /* Initialize the entry's timer. */
396 syncache_timeout(syncache_percpu, sc, 0);
398 /* Put it into the bucket. */
399 TAILQ_INSERT_TAIL(&sch->sch_bucket, sc, sc_hash);
400 sch->sch_length++;
401 syncache_percpu->cache_count++;
402 tcpstat.tcps_sc_added++;
405 void
406 syncache_destroy(struct tcpcb *tp, struct tcpcb *tp_inh)
408 struct tcp_syncache_percpu *syncache_percpu;
409 int i;
411 ASSERT_NETISR_NCPUS(mycpuid);
413 syncache_percpu = tcp_syncache_percpu[mycpu->gd_cpuid];
414 for (i = 0; i < tcp_syncache.hashsize; i++) {
415 struct syncache_head *bucket;
416 struct syncache *sc;
418 bucket = &syncache_percpu->hashbase[i];
419 TAILQ_FOREACH(sc, &bucket->sch_bucket, sc_hash) {
420 if (sc->sc_tp == tp)
421 sc->sc_tp = tp_inh;
426 static void
427 syncache_drop(struct syncache *sc, struct syncache_head *sch)
429 struct tcp_syncache_percpu *syncache_percpu;
430 #ifdef INET6
431 const boolean_t isipv6 = sc->sc_inc.inc_isipv6;
432 #else
433 const boolean_t isipv6 = FALSE;
434 #endif
436 syncache_percpu = tcp_syncache_percpu[mycpu->gd_cpuid];
438 if (sch == NULL) {
439 if (isipv6) {
440 sch = &syncache_percpu->hashbase[
441 SYNCACHE_HASH6(&sc->sc_inc, tcp_syncache.hashmask)];
442 } else {
443 sch = &syncache_percpu->hashbase[
444 SYNCACHE_HASH(&sc->sc_inc, tcp_syncache.hashmask)];
448 TAILQ_REMOVE(&sch->sch_bucket, sc, sc_hash);
449 sch->sch_length--;
450 syncache_percpu->cache_count--;
453 * Cleanup
455 sc->sc_tp = NULL;
458 * Remove the entry from the syncache timer/timeout queue. Note
459 * that we do not try to stop any running timer since we do not know
460 * whether the timer's message is in-transit or not. Since timeouts
461 * are fairly long, taking an unneeded callout does not detrimentally
462 * effect performance.
464 TAILQ_REMOVE(&syncache_percpu->timerq[sc->sc_rxtslot].list, sc,
465 sc_timerq);
467 syncache_free(sc);
471 * Place a timeout message on the TCP thread's message queue.
472 * This routine runs in soft interrupt context.
474 * An invariant is for this routine to be called, the callout must
475 * have been active. Note that the callout is not deactivated until
476 * after the message has been processed in syncache_timer_handler() below.
478 static void
479 syncache_timer(void *p)
481 struct netmsg_base *msg = p;
483 KKASSERT(mycpuid < netisr_ncpus);
485 crit_enter();
486 if (msg->lmsg.ms_flags & MSGF_DONE)
487 netisr_sendmsg_oncpu(msg);
488 crit_exit();
492 * Service a timer message queued by timer expiration.
493 * This routine runs in the TCP protocol thread.
495 * Walk the timer queues, looking for SYN,ACKs that need to be retransmitted.
496 * If we have retransmitted an entry the maximum number of times, expire it.
498 * When we finish processing timed-out entries, we restart the timer if there
499 * are any entries still on the queue and deactivate it otherwise. Only after
500 * a timer has been deactivated here can it be restarted by syncache_timeout().
502 static void
503 syncache_timer_handler(netmsg_t msg)
505 struct tcp_syncache_percpu *syncache_percpu;
506 struct syncache *nsc;
507 struct syncache_timerq *tq;
508 int slot;
510 ASSERT_NETISR_NCPUS(mycpuid);
512 /* Reply ASAP. */
513 crit_enter();
514 netisr_replymsg(&msg->base, 0);
515 crit_exit();
517 syncache_percpu = tcp_syncache_percpu[mycpu->gd_cpuid];
519 slot = msg->lmsg.u.ms_result;
520 KASSERT(slot <= SYNCACHE_MAXREXMTS,
521 ("syncache: invalid slot %d", slot));
522 tq = &syncache_percpu->timerq[slot];
524 nsc = TAILQ_FIRST(&tq->list);
525 while (nsc != NULL) {
526 struct syncache *sc;
528 if (ticks < nsc->sc_rxttime)
529 break; /* finished because timerq sorted by time */
531 sc = nsc;
532 if (sc->sc_tp == NULL) {
533 nsc = TAILQ_NEXT(sc, sc_timerq);
534 syncache_drop(sc, NULL);
535 tcpstat.tcps_sc_stale++;
536 continue;
538 if (slot == SYNCACHE_MAXREXMTS ||
539 slot >= tcp_syncache.rexmt_limit ||
540 sc->sc_tp->t_inpcb->inp_gencnt != sc->sc_inp_gencnt) {
541 nsc = TAILQ_NEXT(sc, sc_timerq);
542 syncache_drop(sc, NULL);
543 tcpstat.tcps_sc_stale++;
544 continue;
547 * syncache_respond() may call back into the syncache to
548 * to modify another entry, so do not obtain the next
549 * entry on the timer chain until it has completed.
551 syncache_respond(sc, NULL);
552 tcpstat.tcps_sc_retransmitted++;
553 nsc = TAILQ_NEXT(sc, sc_timerq);
554 TAILQ_REMOVE(&tq->list, sc, sc_timerq);
555 syncache_timeout(syncache_percpu, sc, slot + 1);
558 if (nsc != NULL) {
559 callout_reset(&tq->timeo, nsc->sc_rxttime - ticks,
560 syncache_timer, &tq->nm);
561 } else {
562 callout_deactivate(&tq->timeo);
567 * Find an entry in the syncache.
569 static struct syncache *
570 syncache_lookup(struct in_conninfo *inc, struct syncache_head **schp)
572 struct tcp_syncache_percpu *syncache_percpu;
573 struct syncache *sc;
574 struct syncache_head *sch;
576 syncache_percpu = tcp_syncache_percpu[mycpu->gd_cpuid];
577 #ifdef INET6
578 if (inc->inc_isipv6) {
579 sch = &syncache_percpu->hashbase[
580 SYNCACHE_HASH6(inc, tcp_syncache.hashmask)];
581 *schp = sch;
582 TAILQ_FOREACH(sc, &sch->sch_bucket, sc_hash)
583 if (ENDPTS6_EQ(&inc->inc_ie, &sc->sc_inc.inc_ie))
584 return (sc);
585 } else
586 #endif
588 sch = &syncache_percpu->hashbase[
589 SYNCACHE_HASH(inc, tcp_syncache.hashmask)];
590 *schp = sch;
591 TAILQ_FOREACH(sc, &sch->sch_bucket, sc_hash) {
592 #ifdef INET6
593 if (sc->sc_inc.inc_isipv6)
594 continue;
595 #endif
596 if (ENDPTS_EQ(&inc->inc_ie, &sc->sc_inc.inc_ie))
597 return (sc);
600 return (NULL);
604 * This function is called when we get a RST for a
605 * non-existent connection, so that we can see if the
606 * connection is in the syn cache. If it is, zap it.
608 void
609 syncache_chkrst(struct in_conninfo *inc, struct tcphdr *th)
611 struct syncache *sc;
612 struct syncache_head *sch;
614 ASSERT_NETISR_NCPUS(mycpuid);
616 sc = syncache_lookup(inc, &sch);
617 if (sc == NULL) {
618 return;
621 * If the RST bit is set, check the sequence number to see
622 * if this is a valid reset segment.
623 * RFC 793 page 37:
624 * In all states except SYN-SENT, all reset (RST) segments
625 * are validated by checking their SEQ-fields. A reset is
626 * valid if its sequence number is in the window.
628 * The sequence number in the reset segment is normally an
629 * echo of our outgoing acknowlegement numbers, but some hosts
630 * send a reset with the sequence number at the rightmost edge
631 * of our receive window, and we have to handle this case.
633 if (SEQ_GEQ(th->th_seq, sc->sc_irs) &&
634 SEQ_LEQ(th->th_seq, sc->sc_irs + sc->sc_wnd)) {
635 syncache_drop(sc, sch);
636 tcpstat.tcps_sc_reset++;
640 void
641 syncache_badack(struct in_conninfo *inc)
643 struct syncache *sc;
644 struct syncache_head *sch;
646 ASSERT_NETISR_NCPUS(mycpuid);
648 sc = syncache_lookup(inc, &sch);
649 if (sc != NULL) {
650 syncache_drop(sc, sch);
651 tcpstat.tcps_sc_badack++;
655 void
656 syncache_unreach(struct in_conninfo *inc, const struct tcphdr *th)
658 struct syncache *sc;
659 struct syncache_head *sch;
661 ASSERT_NETISR_NCPUS(mycpuid);
663 /* we are called at splnet() here */
664 sc = syncache_lookup(inc, &sch);
665 if (sc == NULL)
666 return;
668 /* If the sequence number != sc_iss, then it's a bogus ICMP msg */
669 if (ntohl(th->th_seq) != sc->sc_iss)
670 return;
673 * If we've rertransmitted 3 times and this is our second error,
674 * we remove the entry. Otherwise, we allow it to continue on.
675 * This prevents us from incorrectly nuking an entry during a
676 * spurious network outage.
678 * See tcp_notify().
680 if ((sc->sc_flags & SCF_UNREACH) == 0 || sc->sc_rxtslot < 3) {
681 sc->sc_flags |= SCF_UNREACH;
682 return;
684 syncache_drop(sc, sch);
685 tcpstat.tcps_sc_unreach++;
689 * Build a new TCP socket structure from a syncache entry.
691 * This is called from the context of the SYN+ACK
693 static struct socket *
694 syncache_socket(struct syncache *sc, struct socket *lso, struct mbuf *m)
696 struct inpcb *inp = NULL, *linp;
697 struct socket *so;
698 struct tcpcb *tp, *ltp;
699 lwkt_port_t port;
700 #ifdef INET6
701 const boolean_t isipv6 = sc->sc_inc.inc_isipv6;
702 #else
703 const boolean_t isipv6 = FALSE;
704 #endif
705 struct sockaddr_in sin_faddr;
706 struct sockaddr_in6 sin6_faddr;
707 struct sockaddr *faddr;
709 KASSERT(m->m_flags & M_HASH, ("mbuf has no hash"));
711 if (isipv6) {
712 faddr = (struct sockaddr *)&sin6_faddr;
713 sin6_faddr.sin6_family = AF_INET6;
714 sin6_faddr.sin6_len = sizeof(sin6_faddr);
715 sin6_faddr.sin6_addr = sc->sc_inc.inc6_faddr;
716 sin6_faddr.sin6_port = sc->sc_inc.inc_fport;
717 sin6_faddr.sin6_flowinfo = sin6_faddr.sin6_scope_id = 0;
718 } else {
719 faddr = (struct sockaddr *)&sin_faddr;
720 sin_faddr.sin_family = AF_INET;
721 sin_faddr.sin_len = sizeof(sin_faddr);
722 sin_faddr.sin_addr = sc->sc_inc.inc_faddr;
723 sin_faddr.sin_port = sc->sc_inc.inc_fport;
724 bzero(sin_faddr.sin_zero, sizeof(sin_faddr.sin_zero));
728 * Ok, create the full blown connection, and set things up
729 * as they would have been set up if we had created the
730 * connection when the SYN arrived. If we can't create
731 * the connection, abort it.
733 * Set the protocol processing port for the socket to the current
734 * port (that the connection came in on).
736 * NOTE:
737 * We don't keep a reference on the new socket, since its
738 * destruction will run in this thread (netisrN); there is no
739 * race here.
741 so = sonewconn_faddr(lso, SS_ISCONNECTED, faddr,
742 FALSE /* don't ref */);
743 if (so == NULL) {
745 * Drop the connection; we will send a RST if the peer
746 * retransmits the ACK,
748 tcpstat.tcps_listendrop++;
749 goto abort;
753 * Insert new socket into hash list.
755 inp = so->so_pcb;
756 inp->inp_inc.inc_isipv6 = sc->sc_inc.inc_isipv6;
757 if (isipv6) {
758 inp->in6p_laddr = sc->sc_inc.inc6_laddr;
759 } else {
760 KASSERT(INP_ISIPV4(inp), ("not inet pcb"));
761 inp->inp_laddr = sc->sc_inc.inc_laddr;
763 inp->inp_lport = sc->sc_inc.inc_lport;
765 linp = lso->so_pcb;
766 ltp = intotcpcb(linp);
768 tcp_pcbport_insert(ltp, inp);
770 if (isipv6) {
771 struct in6_addr laddr6;
773 * Inherit socket options from the listening socket.
774 * Note that in6p_inputopts are not (and should not be)
775 * copied, since it stores previously received options and is
776 * used to detect if each new option is different than the
777 * previous one and hence should be passed to a user.
778 * If we copied in6p_inputopts, a user would not be able to
779 * receive options just after calling the accept system call.
781 inp->inp_flags |= linp->inp_flags & INP_CONTROLOPTS;
782 if (linp->in6p_outputopts)
783 inp->in6p_outputopts =
784 ip6_copypktopts(linp->in6p_outputopts, M_INTWAIT);
785 inp->in6p_route = sc->sc_route6;
786 sc->sc_route6.ro_rt = NULL;
788 laddr6 = inp->in6p_laddr;
789 if (IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_laddr))
790 inp->in6p_laddr = sc->sc_inc.inc6_laddr;
791 if (in6_pcbconnect(inp, faddr, &thread0)) {
792 inp->in6p_laddr = laddr6;
793 goto abort;
795 port = tcp6_addrport();
796 } else {
797 struct in_addr laddr;
799 inp->inp_options = ip_srcroute(m);
800 if (inp->inp_options == NULL) {
801 inp->inp_options = sc->sc_ipopts;
802 sc->sc_ipopts = NULL;
804 inp->inp_route = sc->sc_route;
805 sc->sc_route.ro_rt = NULL;
807 laddr = inp->inp_laddr;
808 if (inp->inp_laddr.s_addr == INADDR_ANY)
809 inp->inp_laddr = sc->sc_inc.inc_laddr;
810 if (in_pcbconnect(inp, faddr, &thread0)) {
811 inp->inp_laddr = laddr;
812 goto abort;
815 inp->inp_flags |= INP_HASH;
816 inp->inp_hashval = m->m_pkthdr.hash;
817 port = netisr_hashport(inp->inp_hashval);
821 * The current port should be in the context of the SYN+ACK and
822 * so should match the tcp address port.
824 KASSERT(port == &curthread->td_msgport,
825 ("TCP PORT MISMATCH %p vs %p\n", port, &curthread->td_msgport));
827 tp = intotcpcb(inp);
828 TCP_STATE_CHANGE(tp, TCPS_SYN_RECEIVED);
829 tp->iss = sc->sc_iss;
830 tp->irs = sc->sc_irs;
831 tcp_rcvseqinit(tp);
832 tcp_sendseqinit(tp);
833 tp->snd_wnd = sc->sc_sndwnd;
834 tp->snd_wl1 = sc->sc_irs;
835 tp->rcv_up = sc->sc_irs + 1;
836 tp->rcv_wnd = sc->sc_wnd;
837 tp->rcv_adv += tp->rcv_wnd;
839 tp->t_flags = sototcpcb(lso)->t_flags & (TF_NOPUSH | TF_NODELAY);
840 if (sc->sc_flags & SCF_NOOPT)
841 tp->t_flags |= TF_NOOPT;
842 if (sc->sc_flags & SCF_WINSCALE) {
843 tp->t_flags |= TF_REQ_SCALE | TF_RCVD_SCALE;
844 tp->snd_scale = sc->sc_requested_s_scale;
845 tp->request_r_scale = sc->sc_request_r_scale;
847 if (sc->sc_flags & SCF_TIMESTAMP) {
848 tp->t_flags |= TF_REQ_TSTMP | TF_RCVD_TSTMP;
849 tp->ts_recent = sc->sc_tsrecent;
850 tp->ts_recent_age = ticks;
852 if (sc->sc_flags & SCF_SACK_PERMITTED)
853 tp->t_flags |= TF_SACK_PERMITTED;
855 #ifdef TCP_SIGNATURE
856 if (sc->sc_flags & SCF_SIGNATURE)
857 tp->t_flags |= TF_SIGNATURE;
858 #endif /* TCP_SIGNATURE */
860 tp->t_rxtsyn = sc->sc_rxtused;
861 tcp_rmx_init(tp, sc->sc_peer_mss);
864 * Inherit some properties from the listen socket
866 tp->t_keepinit = ltp->t_keepinit;
867 tp->t_keepidle = ltp->t_keepidle;
868 tp->t_keepintvl = ltp->t_keepintvl;
869 tp->t_keepcnt = ltp->t_keepcnt;
870 tp->t_maxidle = ltp->t_maxidle;
872 tcp_create_timermsg(tp, port);
873 tcp_callout_reset(tp, tp->tt_keep, tp->t_keepinit, tcp_timer_keep);
875 tcpstat.tcps_accepts++;
876 return (so);
878 abort:
879 if (so != NULL)
880 soabort_direct(so);
881 return (NULL);
885 * This function gets called when we receive an ACK for a
886 * socket in the LISTEN state. We look up the connection
887 * in the syncache, and if its there, we pull it out of
888 * the cache and turn it into a full-blown connection in
889 * the SYN-RECEIVED state.
892 syncache_expand(struct in_conninfo *inc, struct tcphdr *th, struct socket **sop,
893 struct mbuf *m)
895 struct syncache *sc;
896 struct syncache_head *sch;
897 struct socket *so;
899 ASSERT_NETISR_NCPUS(mycpuid);
901 sc = syncache_lookup(inc, &sch);
902 if (sc == NULL) {
904 * There is no syncache entry, so see if this ACK is
905 * a returning syncookie. To do this, first:
906 * A. See if this socket has had a syncache entry dropped in
907 * the past. We don't want to accept a bogus syncookie
908 * if we've never received a SYN.
909 * B. check that the syncookie is valid. If it is, then
910 * cobble up a fake syncache entry, and return.
912 if (!tcp_syncookies)
913 return (0);
914 sc = syncookie_lookup(inc, th, *sop);
915 if (sc == NULL)
916 return (0);
917 sch = NULL;
918 tcpstat.tcps_sc_recvcookie++;
922 * If seg contains an ACK, but not for our SYN/ACK, send a RST.
924 if (th->th_ack != sc->sc_iss + 1)
925 return (0);
927 so = syncache_socket(sc, *sop, m);
928 if (so == NULL) {
929 #if 0
930 resetandabort:
931 /* XXXjlemon check this - is this correct? */
932 tcp_respond(NULL, m, m, th,
933 th->th_seq + tlen, (tcp_seq)0, TH_RST | TH_ACK);
934 #endif
935 m_freem(m); /* XXX only needed for above */
936 tcpstat.tcps_sc_aborted++;
937 } else {
938 tcpstat.tcps_sc_completed++;
940 if (sch == NULL)
941 syncache_free(sc);
942 else
943 syncache_drop(sc, sch);
944 *sop = so;
945 return (1);
949 * Given a LISTEN socket and an inbound SYN request, add
950 * this to the syn cache, and send back a segment:
951 * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK>
952 * to the source.
954 * IMPORTANT NOTE: We do _NOT_ ACK data that might accompany the SYN.
955 * Doing so would require that we hold onto the data and deliver it
956 * to the application. However, if we are the target of a SYN-flood
957 * DoS attack, an attacker could send data which would eventually
958 * consume all available buffer space if it were ACKed. By not ACKing
959 * the data, we avoid this DoS scenario.
962 syncache_add(struct in_conninfo *inc, struct tcpopt *to, struct tcphdr *th,
963 struct socket *so, struct mbuf *m)
965 struct tcp_syncache_percpu *syncache_percpu;
966 struct tcpcb *tp;
967 struct syncache *sc = NULL;
968 struct syncache_head *sch;
969 struct mbuf *ipopts = NULL;
970 int win;
972 ASSERT_NETISR_NCPUS(mycpuid);
973 KASSERT(m->m_flags & M_HASH, ("mbuf has no hash"));
975 syncache_percpu = tcp_syncache_percpu[mycpu->gd_cpuid];
976 tp = sototcpcb(so);
979 * Remember the IP options, if any.
981 #ifdef INET6
982 if (!inc->inc_isipv6)
983 #endif
984 ipopts = ip_srcroute(m);
987 * See if we already have an entry for this connection.
988 * If we do, resend the SYN,ACK, and reset the retransmit timer.
990 * XXX
991 * The syncache should be re-initialized with the contents
992 * of the new SYN which may have different options.
994 sc = syncache_lookup(inc, &sch);
995 if (sc != NULL) {
996 KASSERT(sc->sc_flags & SCF_HASH, ("syncache has no hash"));
997 KASSERT(sc->sc_hashval == m->m_pkthdr.hash,
998 ("syncache/mbuf hash mismatches"));
1000 tcpstat.tcps_sc_dupsyn++;
1001 if (ipopts) {
1003 * If we were remembering a previous source route,
1004 * forget it and use the new one we've been given.
1006 if (sc->sc_ipopts)
1007 m_free(sc->sc_ipopts);
1008 sc->sc_ipopts = ipopts;
1011 * Update timestamp if present.
1013 if (sc->sc_flags & SCF_TIMESTAMP)
1014 sc->sc_tsrecent = to->to_tsval;
1016 /* Just update the TOF_SACK_PERMITTED for now. */
1017 if (tcp_do_sack && (to->to_flags & TOF_SACK_PERMITTED))
1018 sc->sc_flags |= SCF_SACK_PERMITTED;
1019 else
1020 sc->sc_flags &= ~SCF_SACK_PERMITTED;
1022 /* Update initial send window */
1023 sc->sc_sndwnd = th->th_win;
1026 * PCB may have changed, pick up new values.
1028 sc->sc_tp = tp;
1029 sc->sc_inp_gencnt = tp->t_inpcb->inp_gencnt;
1030 if (syncache_respond(sc, m) == 0) {
1031 TAILQ_REMOVE(
1032 &syncache_percpu->timerq[sc->sc_rxtslot].list,
1033 sc, sc_timerq);
1034 syncache_timeout(syncache_percpu, sc, sc->sc_rxtslot);
1035 tcpstat.tcps_sndacks++;
1036 tcpstat.tcps_sndtotal++;
1038 return (1);
1042 * Fill in the syncache values.
1044 sc = kmalloc(sizeof(struct syncache), M_SYNCACHE, M_WAITOK|M_ZERO);
1045 sc->sc_inp_gencnt = tp->t_inpcb->inp_gencnt;
1046 sc->sc_ipopts = ipopts;
1047 sc->sc_inc.inc_fport = inc->inc_fport;
1048 sc->sc_inc.inc_lport = inc->inc_lport;
1049 sc->sc_tp = tp;
1050 #ifdef INET6
1051 sc->sc_inc.inc_isipv6 = inc->inc_isipv6;
1052 if (inc->inc_isipv6) {
1053 sc->sc_inc.inc6_faddr = inc->inc6_faddr;
1054 sc->sc_inc.inc6_laddr = inc->inc6_laddr;
1055 sc->sc_route6.ro_rt = NULL;
1056 } else
1057 #endif
1059 sc->sc_inc.inc_faddr = inc->inc_faddr;
1060 sc->sc_inc.inc_laddr = inc->inc_laddr;
1061 sc->sc_route.ro_rt = NULL;
1063 sc->sc_irs = th->th_seq;
1064 sc->sc_flags = SCF_HASH;
1065 sc->sc_hashval = m->m_pkthdr.hash;
1066 sc->sc_peer_mss = to->to_flags & TOF_MSS ? to->to_mss : 0;
1067 if (tcp_syncookies)
1068 sc->sc_iss = syncookie_generate(sc);
1069 else
1070 sc->sc_iss = karc4random();
1072 /* Initial receive window: clip ssb_space to [0 .. TCP_MAXWIN] */
1073 win = ssb_space(&so->so_rcv);
1074 win = imax(win, 0);
1075 win = imin(win, TCP_MAXWIN);
1076 sc->sc_wnd = win;
1078 if (tcp_do_rfc1323) {
1080 * A timestamp received in a SYN makes
1081 * it ok to send timestamp requests and replies.
1083 if (to->to_flags & TOF_TS) {
1084 sc->sc_tsrecent = to->to_tsval;
1085 sc->sc_flags |= SCF_TIMESTAMP;
1087 if (to->to_flags & TOF_SCALE) {
1088 int wscale = TCP_MIN_WINSHIFT;
1090 /* Compute proper scaling value from buffer space */
1091 while (wscale < TCP_MAX_WINSHIFT &&
1092 (TCP_MAXWIN << wscale) < so->so_rcv.ssb_hiwat) {
1093 wscale++;
1095 sc->sc_request_r_scale = wscale;
1096 sc->sc_requested_s_scale = to->to_requested_s_scale;
1097 sc->sc_flags |= SCF_WINSCALE;
1100 if (tcp_do_sack && (to->to_flags & TOF_SACK_PERMITTED))
1101 sc->sc_flags |= SCF_SACK_PERMITTED;
1102 if (tp->t_flags & TF_NOOPT)
1103 sc->sc_flags = SCF_NOOPT;
1104 #ifdef TCP_SIGNATURE
1106 * If listening socket requested TCP digests, and received SYN
1107 * contains the option, flag this in the syncache so that
1108 * syncache_respond() will do the right thing with the SYN+ACK.
1109 * XXX Currently we always record the option by default and will
1110 * attempt to use it in syncache_respond().
1112 if (to->to_flags & TOF_SIGNATURE)
1113 sc->sc_flags = SCF_SIGNATURE;
1114 #endif /* TCP_SIGNATURE */
1115 sc->sc_sndwnd = th->th_win;
1117 if (syncache_respond(sc, m) == 0) {
1118 syncache_insert(sc, sch);
1119 tcpstat.tcps_sndacks++;
1120 tcpstat.tcps_sndtotal++;
1121 } else {
1122 syncache_free(sc);
1123 tcpstat.tcps_sc_dropped++;
1125 return (1);
1128 static int
1129 syncache_respond(struct syncache *sc, struct mbuf *m)
1131 u_int8_t *optp;
1132 int optlen, error;
1133 u_int16_t tlen, hlen, mssopt;
1134 struct ip *ip = NULL;
1135 struct rtentry *rt;
1136 struct tcphdr *th;
1137 struct ip6_hdr *ip6 = NULL;
1138 #ifdef INET6
1139 const boolean_t isipv6 = sc->sc_inc.inc_isipv6;
1140 #else
1141 const boolean_t isipv6 = FALSE;
1142 #endif
1144 if (isipv6) {
1145 rt = tcp_rtlookup6(&sc->sc_inc);
1146 if (rt != NULL)
1147 mssopt = rt->rt_ifp->if_mtu -
1148 (sizeof(struct ip6_hdr) + sizeof(struct tcphdr));
1149 else
1150 mssopt = tcp_v6mssdflt;
1151 hlen = sizeof(struct ip6_hdr);
1152 } else {
1153 rt = tcp_rtlookup(&sc->sc_inc);
1154 if (rt != NULL)
1155 mssopt = rt->rt_ifp->if_mtu -
1156 (sizeof(struct ip) + sizeof(struct tcphdr));
1157 else
1158 mssopt = tcp_mssdflt;
1159 hlen = sizeof(struct ip);
1162 /* Compute the size of the TCP options. */
1163 if (sc->sc_flags & SCF_NOOPT) {
1164 optlen = 0;
1165 } else {
1166 optlen = TCPOLEN_MAXSEG +
1167 ((sc->sc_flags & SCF_WINSCALE) ? 4 : 0) +
1168 ((sc->sc_flags & SCF_TIMESTAMP) ? TCPOLEN_TSTAMP_APPA : 0) +
1169 ((sc->sc_flags & SCF_SACK_PERMITTED) ?
1170 TCPOLEN_SACK_PERMITTED_ALIGNED : 0);
1171 #ifdef TCP_SIGNATURE
1172 optlen += ((sc->sc_flags & SCF_SIGNATURE) ?
1173 (TCPOLEN_SIGNATURE + 2) : 0);
1174 #endif /* TCP_SIGNATURE */
1176 tlen = hlen + sizeof(struct tcphdr) + optlen;
1179 * XXX
1180 * assume that the entire packet will fit in a header mbuf
1182 KASSERT(max_linkhdr + tlen <= MHLEN, ("syncache: mbuf too small"));
1185 * XXX shouldn't this reuse the mbuf if possible ?
1186 * Create the IP+TCP header from scratch.
1188 if (m)
1189 m_freem(m);
1191 m = m_gethdr(M_NOWAIT, MT_HEADER);
1192 if (m == NULL)
1193 return (ENOBUFS);
1194 m->m_data += max_linkhdr;
1195 m->m_len = tlen;
1196 m->m_pkthdr.len = tlen;
1197 m->m_pkthdr.rcvif = NULL;
1198 if (tcp_prio_synack)
1199 m->m_flags |= M_PRIO;
1201 if (isipv6) {
1202 ip6 = mtod(m, struct ip6_hdr *);
1203 ip6->ip6_vfc = IPV6_VERSION;
1204 ip6->ip6_nxt = IPPROTO_TCP;
1205 ip6->ip6_src = sc->sc_inc.inc6_laddr;
1206 ip6->ip6_dst = sc->sc_inc.inc6_faddr;
1207 ip6->ip6_plen = htons(tlen - hlen);
1208 /* ip6_hlim is set after checksum */
1209 /* ip6_flow = ??? */
1211 th = (struct tcphdr *)(ip6 + 1);
1212 } else {
1213 ip = mtod(m, struct ip *);
1214 ip->ip_v = IPVERSION;
1215 ip->ip_hl = sizeof(struct ip) >> 2;
1216 ip->ip_len = tlen;
1217 ip->ip_id = 0;
1218 ip->ip_off = 0;
1219 ip->ip_sum = 0;
1220 ip->ip_p = IPPROTO_TCP;
1221 ip->ip_src = sc->sc_inc.inc_laddr;
1222 ip->ip_dst = sc->sc_inc.inc_faddr;
1223 ip->ip_ttl = sc->sc_tp->t_inpcb->inp_ip_ttl; /* XXX */
1224 ip->ip_tos = sc->sc_tp->t_inpcb->inp_ip_tos; /* XXX */
1227 * See if we should do MTU discovery. Route lookups are
1228 * expensive, so we will only unset the DF bit if:
1230 * 1) path_mtu_discovery is disabled
1231 * 2) the SCF_UNREACH flag has been set
1233 if (path_mtu_discovery
1234 && ((sc->sc_flags & SCF_UNREACH) == 0)) {
1235 ip->ip_off |= IP_DF;
1238 th = (struct tcphdr *)(ip + 1);
1240 th->th_sport = sc->sc_inc.inc_lport;
1241 th->th_dport = sc->sc_inc.inc_fport;
1243 th->th_seq = htonl(sc->sc_iss);
1244 th->th_ack = htonl(sc->sc_irs + 1);
1245 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2;
1246 th->th_x2 = 0;
1247 th->th_flags = TH_SYN | TH_ACK;
1248 th->th_win = htons(sc->sc_wnd);
1249 th->th_urp = 0;
1251 /* Tack on the TCP options. */
1252 if (optlen == 0)
1253 goto no_options;
1254 optp = (u_int8_t *)(th + 1);
1255 *optp++ = TCPOPT_MAXSEG;
1256 *optp++ = TCPOLEN_MAXSEG;
1257 *optp++ = (mssopt >> 8) & 0xff;
1258 *optp++ = mssopt & 0xff;
1260 if (sc->sc_flags & SCF_WINSCALE) {
1261 *((u_int32_t *)optp) = htonl(TCPOPT_NOP << 24 |
1262 TCPOPT_WINDOW << 16 | TCPOLEN_WINDOW << 8 |
1263 sc->sc_request_r_scale);
1264 optp += 4;
1267 if (sc->sc_flags & SCF_TIMESTAMP) {
1268 u_int32_t *lp = (u_int32_t *)(optp);
1270 /* Form timestamp option as shown in appendix A of RFC 1323. */
1271 *lp++ = htonl(TCPOPT_TSTAMP_HDR);
1272 *lp++ = htonl(ticks);
1273 *lp = htonl(sc->sc_tsrecent);
1274 optp += TCPOLEN_TSTAMP_APPA;
1277 #ifdef TCP_SIGNATURE
1279 * Handle TCP-MD5 passive opener response.
1281 if (sc->sc_flags & SCF_SIGNATURE) {
1282 u_int8_t *bp = optp;
1283 int i;
1285 *bp++ = TCPOPT_SIGNATURE;
1286 *bp++ = TCPOLEN_SIGNATURE;
1287 for (i = 0; i < TCP_SIGLEN; i++)
1288 *bp++ = 0;
1289 tcpsignature_compute(m, 0, optlen,
1290 optp + 2, IPSEC_DIR_OUTBOUND);
1291 *bp++ = TCPOPT_NOP;
1292 *bp++ = TCPOPT_EOL;
1293 optp += TCPOLEN_SIGNATURE + 2;
1295 #endif /* TCP_SIGNATURE */
1297 if (sc->sc_flags & SCF_SACK_PERMITTED) {
1298 *((u_int32_t *)optp) = htonl(TCPOPT_SACK_PERMITTED_ALIGNED);
1299 optp += TCPOLEN_SACK_PERMITTED_ALIGNED;
1302 no_options:
1303 if (isipv6) {
1304 struct route_in6 *ro6 = &sc->sc_route6;
1306 th->th_sum = 0;
1307 th->th_sum = in6_cksum(m, IPPROTO_TCP, hlen, tlen - hlen);
1308 ip6->ip6_hlim = in6_selecthlim(NULL,
1309 ro6->ro_rt ? ro6->ro_rt->rt_ifp : NULL);
1310 error = ip6_output(m, NULL, ro6, 0, NULL, NULL,
1311 sc->sc_tp->t_inpcb);
1312 } else {
1313 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
1314 htons(tlen - hlen + IPPROTO_TCP));
1315 m->m_pkthdr.csum_flags = CSUM_TCP;
1316 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
1317 m->m_pkthdr.csum_thlen = sizeof(struct tcphdr) + optlen;
1318 KASSERT(sc->sc_flags & SCF_HASH, ("syncache has no hash"));
1319 m_sethash(m, sc->sc_hashval);
1320 error = ip_output(m, sc->sc_ipopts, &sc->sc_route,
1321 IP_DEBUGROUTE, NULL, sc->sc_tp->t_inpcb);
1323 return (error);
1327 * cookie layers:
1329 * |. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .|
1330 * | peer iss |
1331 * | MD5(laddr,faddr,secret,lport,fport) |. . . . . . .|
1332 * | 0 |(A)| |
1333 * (A): peer mss index
1337 * The values below are chosen to minimize the size of the tcp_secret
1338 * table, as well as providing roughly a 16 second lifetime for the cookie.
1341 #define SYNCOOKIE_WNDBITS 5 /* exposed bits for window indexing */
1342 #define SYNCOOKIE_TIMESHIFT 1 /* scale ticks to window time units */
1344 #define SYNCOOKIE_WNDMASK ((1 << SYNCOOKIE_WNDBITS) - 1)
1345 #define SYNCOOKIE_NSECRETS (1 << SYNCOOKIE_WNDBITS)
1346 #define SYNCOOKIE_TIMEOUT \
1347 (hz * (1 << SYNCOOKIE_WNDBITS) / (1 << SYNCOOKIE_TIMESHIFT))
1348 #define SYNCOOKIE_DATAMASK ((3 << SYNCOOKIE_WNDBITS) | SYNCOOKIE_WNDMASK)
1350 static struct {
1351 u_int32_t ts_secbits[4];
1352 u_int ts_expire;
1353 } tcp_secret[SYNCOOKIE_NSECRETS];
1355 static int tcp_msstab[] = { 0, 536, 1460, 8960 };
1357 static MD5_CTX syn_ctx;
1359 #define MD5Add(v) MD5Update(&syn_ctx, (u_char *)&v, sizeof(v))
1361 struct md5_add {
1362 u_int32_t laddr, faddr;
1363 u_int32_t secbits[4];
1364 u_int16_t lport, fport;
1367 #ifdef CTASSERT
1368 CTASSERT(sizeof(struct md5_add) == 28);
1369 #endif
1372 * Consider the problem of a recreated (and retransmitted) cookie. If the
1373 * original SYN was accepted, the connection is established. The second
1374 * SYN is inflight, and if it arrives with an ISN that falls within the
1375 * receive window, the connection is killed.
1377 * However, since cookies have other problems, this may not be worth
1378 * worrying about.
1381 static u_int32_t
1382 syncookie_generate(struct syncache *sc)
1384 u_int32_t md5_buffer[4];
1385 u_int32_t data;
1386 int idx, i;
1387 struct md5_add add;
1388 #ifdef INET6
1389 const boolean_t isipv6 = sc->sc_inc.inc_isipv6;
1390 #else
1391 const boolean_t isipv6 = FALSE;
1392 #endif
1394 idx = ((ticks << SYNCOOKIE_TIMESHIFT) / hz) & SYNCOOKIE_WNDMASK;
1395 if (tcp_secret[idx].ts_expire < ticks) {
1396 for (i = 0; i < 4; i++)
1397 tcp_secret[idx].ts_secbits[i] = karc4random();
1398 tcp_secret[idx].ts_expire = ticks + SYNCOOKIE_TIMEOUT;
1400 for (data = NELEM(tcp_msstab) - 1; data > 0; data--)
1401 if (tcp_msstab[data] <= sc->sc_peer_mss)
1402 break;
1403 data = (data << SYNCOOKIE_WNDBITS) | idx;
1404 data ^= sc->sc_irs; /* peer's iss */
1405 MD5Init(&syn_ctx);
1406 if (isipv6) {
1407 MD5Add(sc->sc_inc.inc6_laddr);
1408 MD5Add(sc->sc_inc.inc6_faddr);
1409 add.laddr = 0;
1410 add.faddr = 0;
1411 } else {
1412 add.laddr = sc->sc_inc.inc_laddr.s_addr;
1413 add.faddr = sc->sc_inc.inc_faddr.s_addr;
1415 add.lport = sc->sc_inc.inc_lport;
1416 add.fport = sc->sc_inc.inc_fport;
1417 add.secbits[0] = tcp_secret[idx].ts_secbits[0];
1418 add.secbits[1] = tcp_secret[idx].ts_secbits[1];
1419 add.secbits[2] = tcp_secret[idx].ts_secbits[2];
1420 add.secbits[3] = tcp_secret[idx].ts_secbits[3];
1421 MD5Add(add);
1422 MD5Final((u_char *)&md5_buffer, &syn_ctx);
1423 data ^= (md5_buffer[0] & ~SYNCOOKIE_WNDMASK);
1424 return (data);
1427 static struct syncache *
1428 syncookie_lookup(struct in_conninfo *inc, struct tcphdr *th, struct socket *so)
1430 u_int32_t md5_buffer[4];
1431 struct syncache *sc;
1432 u_int32_t data;
1433 int wnd, idx;
1434 struct md5_add add;
1436 data = (th->th_ack - 1) ^ (th->th_seq - 1); /* remove ISS */
1437 idx = data & SYNCOOKIE_WNDMASK;
1438 if (tcp_secret[idx].ts_expire < ticks ||
1439 sototcpcb(so)->ts_recent + SYNCOOKIE_TIMEOUT < ticks)
1440 return (NULL);
1441 MD5Init(&syn_ctx);
1442 #ifdef INET6
1443 if (inc->inc_isipv6) {
1444 MD5Add(inc->inc6_laddr);
1445 MD5Add(inc->inc6_faddr);
1446 add.laddr = 0;
1447 add.faddr = 0;
1448 } else
1449 #endif
1451 add.laddr = inc->inc_laddr.s_addr;
1452 add.faddr = inc->inc_faddr.s_addr;
1454 add.lport = inc->inc_lport;
1455 add.fport = inc->inc_fport;
1456 add.secbits[0] = tcp_secret[idx].ts_secbits[0];
1457 add.secbits[1] = tcp_secret[idx].ts_secbits[1];
1458 add.secbits[2] = tcp_secret[idx].ts_secbits[2];
1459 add.secbits[3] = tcp_secret[idx].ts_secbits[3];
1460 MD5Add(add);
1461 MD5Final((u_char *)&md5_buffer, &syn_ctx);
1462 data ^= md5_buffer[0];
1463 if (data & ~SYNCOOKIE_DATAMASK)
1464 return (NULL);
1465 data = data >> SYNCOOKIE_WNDBITS;
1468 * Fill in the syncache values.
1469 * XXX duplicate code from syncache_add
1471 sc = kmalloc(sizeof(struct syncache), M_SYNCACHE, M_WAITOK|M_ZERO);
1472 sc->sc_ipopts = NULL;
1473 sc->sc_inc.inc_fport = inc->inc_fport;
1474 sc->sc_inc.inc_lport = inc->inc_lport;
1475 #ifdef INET6
1476 sc->sc_inc.inc_isipv6 = inc->inc_isipv6;
1477 if (inc->inc_isipv6) {
1478 sc->sc_inc.inc6_faddr = inc->inc6_faddr;
1479 sc->sc_inc.inc6_laddr = inc->inc6_laddr;
1480 sc->sc_route6.ro_rt = NULL;
1481 } else
1482 #endif
1484 sc->sc_inc.inc_faddr = inc->inc_faddr;
1485 sc->sc_inc.inc_laddr = inc->inc_laddr;
1486 sc->sc_route.ro_rt = NULL;
1488 sc->sc_irs = th->th_seq - 1;
1489 sc->sc_iss = th->th_ack - 1;
1490 wnd = ssb_space(&so->so_rcv);
1491 wnd = imax(wnd, 0);
1492 wnd = imin(wnd, TCP_MAXWIN);
1493 sc->sc_wnd = wnd;
1494 sc->sc_flags = 0;
1495 sc->sc_rxtslot = 0;
1496 sc->sc_peer_mss = tcp_msstab[data];
1497 return (sc);
1500 static int
1501 syncache_sysctl_count(SYSCTL_HANDLER_ARGS)
1503 u_int count = 0;
1504 int cpu;
1506 for (cpu = 0; cpu < netisr_ncpus; ++cpu)
1507 count += tcp_syncache_percpu[cpu]->cache_count;
1508 return sysctl_handle_int(oidp, &count, 0, req);