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>
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>
105 #include <netinet/icmp6.h>
106 #include <netinet6/nd6.h>
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>
119 #include <netinet6/ipsec.h>
121 #include <netinet6/ipsec6.h>
123 #include <netproto/key/key.h>
127 #include <netproto/ipsec/ipsec.h>
129 #include <netproto/ipsec/ipsec6.h>
131 #include <netproto/ipsec/key.h>
133 #endif /*FAST_IPSEC*/
135 static int tcp_syncookies
= 1;
136 SYSCTL_INT(_net_inet_tcp
, OID_AUTO
, syncookies
, CTLFLAG_RW
,
138 "Use TCP SYN cookies if the syncache overflows");
140 static void syncache_drop(struct syncache
*, struct syncache_head
*);
141 static void syncache_free(struct syncache
*);
142 static void syncache_insert(struct syncache
*, struct syncache_head
*);
143 struct syncache
*syncache_lookup(struct in_conninfo
*, struct syncache_head
**);
144 static int syncache_respond(struct syncache
*, struct mbuf
*);
145 static struct socket
*syncache_socket(struct syncache
*, struct socket
*,
147 static void syncache_timer(void *);
148 static u_int32_t
syncookie_generate(struct syncache
*);
149 static struct syncache
*syncookie_lookup(struct in_conninfo
*,
150 struct tcphdr
*, struct socket
*);
153 * Transmit the SYN,ACK fewer times than TCP_MAXRXTSHIFT specifies.
154 * 3 retransmits corresponds to a timeout of (1 + 2 + 4 + 8 == 15) seconds,
155 * the odds are that the user has given up attempting to connect by then.
157 #define SYNCACHE_MAXREXMTS 3
159 /* Arbitrary values */
160 #define TCP_SYNCACHE_HASHSIZE 512
161 #define TCP_SYNCACHE_BUCKETLIMIT 30
163 struct netmsg_sc_timer
{
164 struct netmsg_base base
;
165 struct msgrec
*nm_mrec
; /* back pointer to containing msgrec */
169 struct netmsg_sc_timer msg
;
170 lwkt_port_t port
; /* constant after init */
171 int slot
; /* constant after init */
174 static void syncache_timer_handler(netmsg_t
);
176 struct tcp_syncache
{
184 static struct tcp_syncache tcp_syncache
;
186 TAILQ_HEAD(syncache_list
, syncache
);
188 struct tcp_syncache_percpu
{
189 struct syncache_head
*hashbase
;
191 struct syncache_list timerq
[SYNCACHE_MAXREXMTS
+ 1];
192 struct callout tt_timerq
[SYNCACHE_MAXREXMTS
+ 1];
193 struct msgrec mrec
[SYNCACHE_MAXREXMTS
+ 1];
195 static struct tcp_syncache_percpu tcp_syncache_percpu
[MAXCPU
];
197 static struct lwkt_port syncache_null_rport
;
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_timeout(struct tcp_syncache_percpu
*syncache_percpu
,
244 struct syncache
*sc
, int slot
)
248 * Record that SYN|ACK was lost.
249 * Needed by RFC3390 and RFC6298.
251 sc
->sc_flags
|= SCF_SYN_WASLOST
;
253 sc
->sc_rxtslot
= slot
;
254 sc
->sc_rxttime
= ticks
+ TCPTV_RTOBASE
* tcp_backoff
[slot
];
255 TAILQ_INSERT_TAIL(&syncache_percpu
->timerq
[slot
], sc
, sc_timerq
);
256 if (!callout_active(&syncache_percpu
->tt_timerq
[slot
])) {
257 callout_reset(&syncache_percpu
->tt_timerq
[slot
],
258 TCPTV_RTOBASE
* tcp_backoff
[slot
],
260 &syncache_percpu
->mrec
[slot
]);
265 syncache_free(struct syncache
*sc
)
269 const boolean_t isipv6
= sc
->sc_inc
.inc_isipv6
;
271 const boolean_t isipv6
= FALSE
;
275 m_free(sc
->sc_ipopts
);
277 rt
= isipv6
? sc
->sc_route6
.ro_rt
: sc
->sc_route
.ro_rt
;
280 * If this is the only reference to a protocol-cloned
281 * route, remove it immediately.
283 if ((rt
->rt_flags
& RTF_WASCLONED
) && rt
->rt_refcnt
== 1)
284 rtrequest(RTM_DELETE
, rt_key(rt
), rt
->rt_gateway
,
285 rt_mask(rt
), rt
->rt_flags
, NULL
);
288 kfree(sc
, M_SYNCACHE
);
296 tcp_syncache
.hashsize
= TCP_SYNCACHE_HASHSIZE
;
297 tcp_syncache
.bucket_limit
= TCP_SYNCACHE_BUCKETLIMIT
;
298 tcp_syncache
.cache_limit
=
299 tcp_syncache
.hashsize
* tcp_syncache
.bucket_limit
;
300 tcp_syncache
.rexmt_limit
= SYNCACHE_MAXREXMTS
;
301 tcp_syncache
.hash_secret
= karc4random();
303 TUNABLE_INT_FETCH("net.inet.tcp.syncache.hashsize",
304 &tcp_syncache
.hashsize
);
305 TUNABLE_INT_FETCH("net.inet.tcp.syncache.cachelimit",
306 &tcp_syncache
.cache_limit
);
307 TUNABLE_INT_FETCH("net.inet.tcp.syncache.bucketlimit",
308 &tcp_syncache
.bucket_limit
);
309 if (!powerof2(tcp_syncache
.hashsize
)) {
310 kprintf("WARNING: syncache hash size is not a power of 2.\n");
311 tcp_syncache
.hashsize
= 512; /* safe default */
313 tcp_syncache
.hashmask
= tcp_syncache
.hashsize
- 1;
315 lwkt_initport_replyonly_null(&syncache_null_rport
);
317 for (cpu
= 0; cpu
< ncpus2
; cpu
++) {
318 struct tcp_syncache_percpu
*syncache_percpu
;
320 syncache_percpu
= &tcp_syncache_percpu
[cpu
];
321 /* Allocate the hash table. */
322 syncache_percpu
->hashbase
= kmalloc(tcp_syncache
.hashsize
* sizeof(struct syncache_head
),
323 M_SYNCACHE
, M_WAITOK
);
325 /* Initialize the hash buckets. */
326 for (i
= 0; i
< tcp_syncache
.hashsize
; i
++) {
327 struct syncache_head
*bucket
;
329 bucket
= &syncache_percpu
->hashbase
[i
];
330 TAILQ_INIT(&bucket
->sch_bucket
);
331 bucket
->sch_length
= 0;
334 for (i
= 0; i
<= SYNCACHE_MAXREXMTS
; i
++) {
335 /* Initialize the timer queues. */
336 TAILQ_INIT(&syncache_percpu
->timerq
[i
]);
337 callout_init_mp(&syncache_percpu
->tt_timerq
[i
]);
339 syncache_percpu
->mrec
[i
].slot
= i
;
340 syncache_percpu
->mrec
[i
].port
= cpu_portfn(cpu
);
341 syncache_percpu
->mrec
[i
].msg
.nm_mrec
=
342 &syncache_percpu
->mrec
[i
];
343 netmsg_init(&syncache_percpu
->mrec
[i
].msg
.base
,
344 NULL
, &syncache_null_rport
,
345 0, syncache_timer_handler
);
351 syncache_insert(struct syncache
*sc
, struct syncache_head
*sch
)
353 struct tcp_syncache_percpu
*syncache_percpu
;
354 struct syncache
*sc2
;
357 syncache_percpu
= &tcp_syncache_percpu
[mycpu
->gd_cpuid
];
360 * Make sure that we don't overflow the per-bucket
361 * limit or the total cache size limit.
363 if (sch
->sch_length
>= tcp_syncache
.bucket_limit
) {
365 * The bucket is full, toss the oldest element.
367 sc2
= TAILQ_FIRST(&sch
->sch_bucket
);
368 sc2
->sc_tp
->ts_recent
= ticks
;
369 syncache_drop(sc2
, sch
);
370 tcpstat
.tcps_sc_bucketoverflow
++;
371 } else if (syncache_percpu
->cache_count
>= tcp_syncache
.cache_limit
) {
373 * The cache is full. Toss the oldest entry in the
374 * entire cache. This is the front entry in the
375 * first non-empty timer queue with the largest
378 for (i
= SYNCACHE_MAXREXMTS
; i
>= 0; i
--) {
379 sc2
= TAILQ_FIRST(&syncache_percpu
->timerq
[i
]);
380 while (sc2
&& (sc2
->sc_flags
& SCF_MARKER
))
381 sc2
= TAILQ_NEXT(sc2
, sc_timerq
);
385 sc2
->sc_tp
->ts_recent
= ticks
;
386 syncache_drop(sc2
, NULL
);
387 tcpstat
.tcps_sc_cacheoverflow
++;
390 /* Initialize the entry's timer. */
391 syncache_timeout(syncache_percpu
, sc
, 0);
393 /* Put it into the bucket. */
394 TAILQ_INSERT_TAIL(&sch
->sch_bucket
, sc
, sc_hash
);
396 syncache_percpu
->cache_count
++;
397 tcpstat
.tcps_sc_added
++;
401 syncache_destroy(struct tcpcb
*tp
)
403 struct tcp_syncache_percpu
*syncache_percpu
;
404 struct syncache_head
*bucket
;
408 syncache_percpu
= &tcp_syncache_percpu
[mycpu
->gd_cpuid
];
411 for (i
= 0; i
< tcp_syncache
.hashsize
; i
++) {
412 bucket
= &syncache_percpu
->hashbase
[i
];
413 TAILQ_FOREACH(sc
, &bucket
->sch_bucket
, sc_hash
) {
421 syncache_drop(struct syncache
*sc
, struct syncache_head
*sch
)
423 struct tcp_syncache_percpu
*syncache_percpu
;
425 const boolean_t isipv6
= sc
->sc_inc
.inc_isipv6
;
427 const boolean_t isipv6
= FALSE
;
430 syncache_percpu
= &tcp_syncache_percpu
[mycpu
->gd_cpuid
];
434 sch
= &syncache_percpu
->hashbase
[
435 SYNCACHE_HASH6(&sc
->sc_inc
, tcp_syncache
.hashmask
)];
437 sch
= &syncache_percpu
->hashbase
[
438 SYNCACHE_HASH(&sc
->sc_inc
, tcp_syncache
.hashmask
)];
442 TAILQ_REMOVE(&sch
->sch_bucket
, sc
, sc_hash
);
444 syncache_percpu
->cache_count
--;
453 * Remove the entry from the syncache timer/timeout queue. Note
454 * that we do not try to stop any running timer since we do not know
455 * whether the timer's message is in-transit or not. Since timeouts
456 * are fairly long, taking an unneeded callout does not detrimentally
457 * effect performance.
459 TAILQ_REMOVE(&syncache_percpu
->timerq
[sc
->sc_rxtslot
], sc
, sc_timerq
);
465 * Place a timeout message on the TCP thread's message queue.
466 * This routine runs in soft interrupt context.
468 * An invariant is for this routine to be called, the callout must
469 * have been active. Note that the callout is not deactivated until
470 * after the message has been processed in syncache_timer_handler() below.
473 syncache_timer(void *p
)
475 struct netmsg_sc_timer
*msg
= p
;
477 lwkt_sendmsg(msg
->nm_mrec
->port
, &msg
->base
.lmsg
);
481 * Service a timer message queued by timer expiration.
482 * This routine runs in the TCP protocol thread.
484 * Walk the timer queues, looking for SYN,ACKs that need to be retransmitted.
485 * If we have retransmitted an entry the maximum number of times, expire it.
487 * When we finish processing timed-out entries, we restart the timer if there
488 * are any entries still on the queue and deactivate it otherwise. Only after
489 * a timer has been deactivated here can it be restarted by syncache_timeout().
492 syncache_timer_handler(netmsg_t msg
)
494 struct tcp_syncache_percpu
*syncache_percpu
;
496 struct syncache marker
;
497 struct syncache_list
*list
;
501 slot
= ((struct netmsg_sc_timer
*)msg
)->nm_mrec
->slot
;
502 syncache_percpu
= &tcp_syncache_percpu
[mycpu
->gd_cpuid
];
504 list
= &syncache_percpu
->timerq
[slot
];
507 * Use a marker to keep our place in the scan. syncache_drop()
508 * can block and cause any next pointer we cache to become stale.
510 marker
.sc_flags
= SCF_MARKER
;
511 TAILQ_INSERT_HEAD(list
, &marker
, sc_timerq
);
513 while ((sc
= TAILQ_NEXT(&marker
, sc_timerq
)) != NULL
) {
517 TAILQ_REMOVE(list
, &marker
, sc_timerq
);
518 TAILQ_INSERT_AFTER(list
, sc
, &marker
, sc_timerq
);
520 if (sc
->sc_flags
& SCF_MARKER
)
523 if (ticks
< sc
->sc_rxttime
)
524 break; /* finished because timerq sorted by time */
525 if (sc
->sc_tp
== NULL
) {
526 syncache_drop(sc
, NULL
);
527 tcpstat
.tcps_sc_stale
++;
530 inp
= sc
->sc_tp
->t_inpcb
;
531 if (slot
== SYNCACHE_MAXREXMTS
||
532 slot
>= tcp_syncache
.rexmt_limit
||
534 inp
->inp_gencnt
!= sc
->sc_inp_gencnt
) {
535 syncache_drop(sc
, NULL
);
536 tcpstat
.tcps_sc_stale
++;
540 * syncache_respond() may call back into the syncache to
541 * to modify another entry, so do not obtain the next
542 * entry on the timer chain until it has completed.
544 syncache_respond(sc
, NULL
);
545 tcpstat
.tcps_sc_retransmitted
++;
546 TAILQ_REMOVE(list
, sc
, sc_timerq
);
547 syncache_timeout(syncache_percpu
, sc
, slot
+ 1);
549 TAILQ_REMOVE(list
, &marker
, sc_timerq
);
552 callout_reset(&syncache_percpu
->tt_timerq
[slot
],
553 sc
->sc_rxttime
- ticks
, syncache_timer
,
554 &syncache_percpu
->mrec
[slot
]);
556 callout_deactivate(&syncache_percpu
->tt_timerq
[slot
]);
558 lwkt_replymsg(&msg
->base
.lmsg
, 0);
562 * Find an entry in the syncache.
565 syncache_lookup(struct in_conninfo
*inc
, struct syncache_head
**schp
)
567 struct tcp_syncache_percpu
*syncache_percpu
;
569 struct syncache_head
*sch
;
571 syncache_percpu
= &tcp_syncache_percpu
[mycpu
->gd_cpuid
];
573 if (inc
->inc_isipv6
) {
574 sch
= &syncache_percpu
->hashbase
[
575 SYNCACHE_HASH6(inc
, tcp_syncache
.hashmask
)];
577 TAILQ_FOREACH(sc
, &sch
->sch_bucket
, sc_hash
)
578 if (ENDPTS6_EQ(&inc
->inc_ie
, &sc
->sc_inc
.inc_ie
))
583 sch
= &syncache_percpu
->hashbase
[
584 SYNCACHE_HASH(inc
, tcp_syncache
.hashmask
)];
586 TAILQ_FOREACH(sc
, &sch
->sch_bucket
, sc_hash
) {
588 if (sc
->sc_inc
.inc_isipv6
)
591 if (ENDPTS_EQ(&inc
->inc_ie
, &sc
->sc_inc
.inc_ie
))
599 * This function is called when we get a RST for a
600 * non-existent connection, so that we can see if the
601 * connection is in the syn cache. If it is, zap it.
604 syncache_chkrst(struct in_conninfo
*inc
, struct tcphdr
*th
)
607 struct syncache_head
*sch
;
609 sc
= syncache_lookup(inc
, &sch
);
614 * If the RST bit is set, check the sequence number to see
615 * if this is a valid reset segment.
617 * In all states except SYN-SENT, all reset (RST) segments
618 * are validated by checking their SEQ-fields. A reset is
619 * valid if its sequence number is in the window.
621 * The sequence number in the reset segment is normally an
622 * echo of our outgoing acknowlegement numbers, but some hosts
623 * send a reset with the sequence number at the rightmost edge
624 * of our receive window, and we have to handle this case.
626 if (SEQ_GEQ(th
->th_seq
, sc
->sc_irs
) &&
627 SEQ_LEQ(th
->th_seq
, sc
->sc_irs
+ sc
->sc_wnd
)) {
628 syncache_drop(sc
, sch
);
629 tcpstat
.tcps_sc_reset
++;
634 syncache_badack(struct in_conninfo
*inc
)
637 struct syncache_head
*sch
;
639 sc
= syncache_lookup(inc
, &sch
);
641 syncache_drop(sc
, sch
);
642 tcpstat
.tcps_sc_badack
++;
647 syncache_unreach(struct in_conninfo
*inc
, struct tcphdr
*th
)
650 struct syncache_head
*sch
;
652 /* we are called at splnet() here */
653 sc
= syncache_lookup(inc
, &sch
);
657 /* If the sequence number != sc_iss, then it's a bogus ICMP msg */
658 if (ntohl(th
->th_seq
) != sc
->sc_iss
)
662 * If we've rertransmitted 3 times and this is our second error,
663 * we remove the entry. Otherwise, we allow it to continue on.
664 * This prevents us from incorrectly nuking an entry during a
665 * spurious network outage.
669 if ((sc
->sc_flags
& SCF_UNREACH
) == 0 || sc
->sc_rxtslot
< 3) {
670 sc
->sc_flags
|= SCF_UNREACH
;
673 syncache_drop(sc
, sch
);
674 tcpstat
.tcps_sc_unreach
++;
678 * Build a new TCP socket structure from a syncache entry.
680 * This is called from the context of the SYN+ACK
682 static struct socket
*
683 syncache_socket(struct syncache
*sc
, struct socket
*lso
, struct mbuf
*m
)
685 struct inpcb
*inp
= NULL
, *linp
;
687 struct tcpcb
*tp
, *ltp
;
690 const boolean_t isipv6
= sc
->sc_inc
.inc_isipv6
;
692 const boolean_t isipv6
= FALSE
;
694 struct sockaddr_in sin_faddr
;
695 struct sockaddr_in6 sin6_faddr
;
696 struct sockaddr
*faddr
;
699 faddr
= (struct sockaddr
*)&sin6_faddr
;
700 sin6_faddr
.sin6_family
= AF_INET6
;
701 sin6_faddr
.sin6_len
= sizeof(sin6_faddr
);
702 sin6_faddr
.sin6_addr
= sc
->sc_inc
.inc6_faddr
;
703 sin6_faddr
.sin6_port
= sc
->sc_inc
.inc_fport
;
704 sin6_faddr
.sin6_flowinfo
= sin6_faddr
.sin6_scope_id
= 0;
706 faddr
= (struct sockaddr
*)&sin_faddr
;
707 sin_faddr
.sin_family
= AF_INET
;
708 sin_faddr
.sin_len
= sizeof(sin_faddr
);
709 sin_faddr
.sin_addr
= sc
->sc_inc
.inc_faddr
;
710 sin_faddr
.sin_port
= sc
->sc_inc
.inc_fport
;
711 bzero(sin_faddr
.sin_zero
, sizeof(sin_faddr
.sin_zero
));
715 * Ok, create the full blown connection, and set things up
716 * as they would have been set up if we had created the
717 * connection when the SYN arrived. If we can't create
718 * the connection, abort it.
720 * Set the protocol processing port for the socket to the current
721 * port (that the connection came in on).
723 so
= sonewconn_faddr(lso
, SS_ISCONNECTED
, faddr
);
726 * Drop the connection; we will send a RST if the peer
727 * retransmits the ACK,
729 tcpstat
.tcps_listendrop
++;
734 * Insert new socket into hash list.
737 inp
->inp_inc
.inc_isipv6
= sc
->sc_inc
.inc_isipv6
;
739 inp
->in6p_laddr
= sc
->sc_inc
.inc6_laddr
;
742 inp
->inp_vflag
&= ~INP_IPV6
;
743 inp
->inp_vflag
|= INP_IPV4
;
744 inp
->inp_flags
&= ~IN6P_IPV6_V6ONLY
;
746 inp
->inp_laddr
= sc
->sc_inc
.inc_laddr
;
748 inp
->inp_lport
= sc
->sc_inc
.inc_lport
;
749 if (in_pcbinsporthash(inp
) != 0) {
751 * Undo the assignments above if we failed to
752 * put the PCB on the hash lists.
755 inp
->in6p_laddr
= kin6addr_any
;
757 inp
->inp_laddr
.s_addr
= INADDR_ANY
;
763 /* copy old policy into new socket's */
764 if (ipsec_copy_policy(linp
->inp_sp
, inp
->inp_sp
))
765 kprintf("syncache_expand: could not copy policy\n");
768 struct in6_addr laddr6
;
770 * Inherit socket options from the listening socket.
771 * Note that in6p_inputopts are not (and should not be)
772 * copied, since it stores previously received options and is
773 * used to detect if each new option is different than the
774 * previous one and hence should be passed to a user.
775 * If we copied in6p_inputopts, a user would not be able to
776 * receive options just after calling the accept system call.
778 inp
->inp_flags
|= linp
->inp_flags
& INP_CONTROLOPTS
;
779 if (linp
->in6p_outputopts
)
780 inp
->in6p_outputopts
=
781 ip6_copypktopts(linp
->in6p_outputopts
, M_INTWAIT
);
782 inp
->in6p_route
= sc
->sc_route6
;
783 sc
->sc_route6
.ro_rt
= NULL
;
785 laddr6
= inp
->in6p_laddr
;
786 if (IN6_IS_ADDR_UNSPECIFIED(&inp
->in6p_laddr
))
787 inp
->in6p_laddr
= sc
->sc_inc
.inc6_laddr
;
788 if (in6_pcbconnect(inp
, faddr
, &thread0
)) {
789 inp
->in6p_laddr
= laddr6
;
793 struct in_addr laddr
;
795 inp
->inp_options
= ip_srcroute(m
);
796 if (inp
->inp_options
== NULL
) {
797 inp
->inp_options
= sc
->sc_ipopts
;
798 sc
->sc_ipopts
= NULL
;
800 inp
->inp_route
= sc
->sc_route
;
801 sc
->sc_route
.ro_rt
= NULL
;
803 laddr
= inp
->inp_laddr
;
804 if (inp
->inp_laddr
.s_addr
== INADDR_ANY
)
805 inp
->inp_laddr
= sc
->sc_inc
.inc_laddr
;
806 if (in_pcbconnect(inp
, faddr
, &thread0
)) {
807 inp
->inp_laddr
= laddr
;
813 * The current port should be in the context of the SYN+ACK and
814 * so should match the tcp address port.
816 * XXX we may be running on the netisr thread instead of a tcp
817 * thread, in which case port will not match
818 * curthread->td_msgport.
821 port
= tcp6_addrport();
823 port
= tcp_addrport(inp
->inp_faddr
.s_addr
, inp
->inp_fport
,
824 inp
->inp_laddr
.s_addr
, inp
->inp_lport
);
826 if (port
!= &curthread
->td_msgport
) {
828 kprintf("TCP PORT MISMATCH %p vs %p\n",
829 port
, &curthread
->td_msgport
);
831 /*KKASSERT(port == &curthread->td_msgport);*/
834 tp
->t_state
= TCPS_SYN_RECEIVED
;
835 tp
->iss
= sc
->sc_iss
;
836 tp
->irs
= sc
->sc_irs
;
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
->requested_s_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
;
859 if (sc
->sc_flags
& SCF_SYN_WASLOST
)
860 tp
->t_flags
|= TF_SYN_WASLOST
;
863 if (sc
->sc_flags
& SCF_SIGNATURE
)
864 tp
->t_flags
|= TF_SIGNATURE
;
865 #endif /* TCP_SIGNATURE */
867 tcp_mss(tp
, sc
->sc_peer_mss
);
870 * Inherit some properties from the listen socket
872 ltp
= intotcpcb(linp
);
873 tp
->t_keepinit
= ltp
->t_keepinit
;
874 tp
->t_keepidle
= ltp
->t_keepidle
;
875 tp
->t_keepintvl
= ltp
->t_keepintvl
;
876 tp
->t_keepcnt
= ltp
->t_keepcnt
;
877 tp
->t_maxidle
= ltp
->t_maxidle
;
879 tcp_create_timermsg(tp
, port
);
880 tcp_callout_reset(tp
, tp
->tt_keep
, tp
->t_keepinit
, tcp_timer_keep
);
882 tcpstat
.tcps_accepts
++;
892 * This function gets called when we receive an ACK for a
893 * socket in the LISTEN state. We look up the connection
894 * in the syncache, and if its there, we pull it out of
895 * the cache and turn it into a full-blown connection in
896 * the SYN-RECEIVED state.
899 syncache_expand(struct in_conninfo
*inc
, struct tcphdr
*th
, struct socket
**sop
,
903 struct syncache_head
*sch
;
906 sc
= syncache_lookup(inc
, &sch
);
909 * There is no syncache entry, so see if this ACK is
910 * a returning syncookie. To do this, first:
911 * A. See if this socket has had a syncache entry dropped in
912 * the past. We don't want to accept a bogus syncookie
913 * if we've never received a SYN.
914 * B. check that the syncookie is valid. If it is, then
915 * cobble up a fake syncache entry, and return.
919 sc
= syncookie_lookup(inc
, th
, *sop
);
923 tcpstat
.tcps_sc_recvcookie
++;
927 * If seg contains an ACK, but not for our SYN/ACK, send a RST.
929 if (th
->th_ack
!= sc
->sc_iss
+ 1)
932 so
= syncache_socket(sc
, *sop
, m
);
936 /* XXXjlemon check this - is this correct? */
937 tcp_respond(NULL
, m
, m
, th
,
938 th
->th_seq
+ tlen
, (tcp_seq
)0, TH_RST
| TH_ACK
);
940 m_freem(m
); /* XXX only needed for above */
941 tcpstat
.tcps_sc_aborted
++;
943 tcpstat
.tcps_sc_completed
++;
948 syncache_drop(sc
, sch
);
954 * Given a LISTEN socket and an inbound SYN request, add
955 * this to the syn cache, and send back a segment:
956 * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK>
959 * IMPORTANT NOTE: We do _NOT_ ACK data that might accompany the SYN.
960 * Doing so would require that we hold onto the data and deliver it
961 * to the application. However, if we are the target of a SYN-flood
962 * DoS attack, an attacker could send data which would eventually
963 * consume all available buffer space if it were ACKed. By not ACKing
964 * the data, we avoid this DoS scenario.
967 syncache_add(struct in_conninfo
*inc
, struct tcpopt
*to
, struct tcphdr
*th
,
968 struct socket
*so
, struct mbuf
*m
)
970 struct tcp_syncache_percpu
*syncache_percpu
;
972 struct syncache
*sc
= NULL
;
973 struct syncache_head
*sch
;
974 struct mbuf
*ipopts
= NULL
;
977 syncache_percpu
= &tcp_syncache_percpu
[mycpu
->gd_cpuid
];
981 * Remember the IP options, if any.
984 if (!inc
->inc_isipv6
)
986 ipopts
= ip_srcroute(m
);
989 * See if we already have an entry for this connection.
990 * If we do, resend the SYN,ACK, and reset the retransmit timer.
993 * The syncache should be re-initialized with the contents
994 * of the new SYN which may have different options.
996 sc
= syncache_lookup(inc
, &sch
);
998 tcpstat
.tcps_sc_dupsyn
++;
1001 * If we were remembering a previous source route,
1002 * forget it and use the new one we've been given.
1005 m_free(sc
->sc_ipopts
);
1006 sc
->sc_ipopts
= ipopts
;
1009 * Update timestamp if present.
1011 if (sc
->sc_flags
& SCF_TIMESTAMP
)
1012 sc
->sc_tsrecent
= to
->to_tsval
;
1014 /* Just update the TOF_SACK_PERMITTED for now. */
1015 if (tcp_do_sack
&& (to
->to_flags
& TOF_SACK_PERMITTED
))
1016 sc
->sc_flags
|= SCF_SACK_PERMITTED
;
1018 sc
->sc_flags
&= ~SCF_SACK_PERMITTED
;
1021 * PCB may have changed, pick up new values.
1024 sc
->sc_inp_gencnt
= tp
->t_inpcb
->inp_gencnt
;
1025 if (syncache_respond(sc
, m
) == 0) {
1026 TAILQ_REMOVE(&syncache_percpu
->timerq
[sc
->sc_rxtslot
],
1028 syncache_timeout(syncache_percpu
, sc
, sc
->sc_rxtslot
);
1029 tcpstat
.tcps_sndacks
++;
1030 tcpstat
.tcps_sndtotal
++;
1036 * Fill in the syncache values.
1038 sc
= kmalloc(sizeof(struct syncache
), M_SYNCACHE
, M_WAITOK
|M_ZERO
);
1039 sc
->sc_inp_gencnt
= tp
->t_inpcb
->inp_gencnt
;
1040 sc
->sc_ipopts
= ipopts
;
1041 sc
->sc_inc
.inc_fport
= inc
->inc_fport
;
1042 sc
->sc_inc
.inc_lport
= inc
->inc_lport
;
1045 sc
->sc_inc
.inc_isipv6
= inc
->inc_isipv6
;
1046 if (inc
->inc_isipv6
) {
1047 sc
->sc_inc
.inc6_faddr
= inc
->inc6_faddr
;
1048 sc
->sc_inc
.inc6_laddr
= inc
->inc6_laddr
;
1049 sc
->sc_route6
.ro_rt
= NULL
;
1053 sc
->sc_inc
.inc_faddr
= inc
->inc_faddr
;
1054 sc
->sc_inc
.inc_laddr
= inc
->inc_laddr
;
1055 sc
->sc_route
.ro_rt
= NULL
;
1057 sc
->sc_irs
= th
->th_seq
;
1059 sc
->sc_peer_mss
= to
->to_flags
& TOF_MSS
? to
->to_mss
: 0;
1061 sc
->sc_iss
= syncookie_generate(sc
);
1063 sc
->sc_iss
= karc4random();
1065 /* Initial receive window: clip ssb_space to [0 .. TCP_MAXWIN] */
1066 win
= ssb_space(&so
->so_rcv
);
1068 win
= imin(win
, TCP_MAXWIN
);
1071 if (tcp_do_rfc1323
) {
1073 * A timestamp received in a SYN makes
1074 * it ok to send timestamp requests and replies.
1076 if (to
->to_flags
& TOF_TS
) {
1077 sc
->sc_tsrecent
= to
->to_tsval
;
1078 sc
->sc_flags
|= SCF_TIMESTAMP
;
1080 if (to
->to_flags
& TOF_SCALE
) {
1081 int wscale
= TCP_MIN_WINSHIFT
;
1083 /* Compute proper scaling value from buffer space */
1084 while (wscale
< TCP_MAX_WINSHIFT
&&
1085 (TCP_MAXWIN
<< wscale
) < so
->so_rcv
.ssb_hiwat
) {
1088 sc
->sc_request_r_scale
= wscale
;
1089 sc
->sc_requested_s_scale
= to
->to_requested_s_scale
;
1090 sc
->sc_flags
|= SCF_WINSCALE
;
1093 if (tcp_do_sack
&& (to
->to_flags
& TOF_SACK_PERMITTED
))
1094 sc
->sc_flags
|= SCF_SACK_PERMITTED
;
1095 if (tp
->t_flags
& TF_NOOPT
)
1096 sc
->sc_flags
= SCF_NOOPT
;
1097 #ifdef TCP_SIGNATURE
1099 * If listening socket requested TCP digests, and received SYN
1100 * contains the option, flag this in the syncache so that
1101 * syncache_respond() will do the right thing with the SYN+ACK.
1102 * XXX Currently we always record the option by default and will
1103 * attempt to use it in syncache_respond().
1105 if (to
->to_flags
& TOF_SIGNATURE
)
1106 sc
->sc_flags
= SCF_SIGNATURE
;
1107 #endif /* TCP_SIGNATURE */
1109 if (syncache_respond(sc
, m
) == 0) {
1110 syncache_insert(sc
, sch
);
1111 tcpstat
.tcps_sndacks
++;
1112 tcpstat
.tcps_sndtotal
++;
1115 tcpstat
.tcps_sc_dropped
++;
1121 syncache_respond(struct syncache
*sc
, struct mbuf
*m
)
1125 u_int16_t tlen
, hlen
, mssopt
;
1126 struct ip
*ip
= NULL
;
1129 struct ip6_hdr
*ip6
= NULL
;
1131 const boolean_t isipv6
= sc
->sc_inc
.inc_isipv6
;
1133 const boolean_t isipv6
= FALSE
;
1137 rt
= tcp_rtlookup6(&sc
->sc_inc
);
1139 mssopt
= rt
->rt_ifp
->if_mtu
-
1140 (sizeof(struct ip6_hdr
) + sizeof(struct tcphdr
));
1142 mssopt
= tcp_v6mssdflt
;
1143 hlen
= sizeof(struct ip6_hdr
);
1145 rt
= tcp_rtlookup(&sc
->sc_inc
);
1147 mssopt
= rt
->rt_ifp
->if_mtu
-
1148 (sizeof(struct ip
) + sizeof(struct tcphdr
));
1150 mssopt
= tcp_mssdflt
;
1151 hlen
= sizeof(struct ip
);
1154 /* Compute the size of the TCP options. */
1155 if (sc
->sc_flags
& SCF_NOOPT
) {
1158 optlen
= TCPOLEN_MAXSEG
+
1159 ((sc
->sc_flags
& SCF_WINSCALE
) ? 4 : 0) +
1160 ((sc
->sc_flags
& SCF_TIMESTAMP
) ? TCPOLEN_TSTAMP_APPA
: 0) +
1161 ((sc
->sc_flags
& SCF_SACK_PERMITTED
) ?
1162 TCPOLEN_SACK_PERMITTED_ALIGNED
: 0);
1163 #ifdef TCP_SIGNATURE
1164 optlen
+= ((sc
->sc_flags
& SCF_SIGNATURE
) ?
1165 (TCPOLEN_SIGNATURE
+ 2) : 0);
1166 #endif /* TCP_SIGNATURE */
1168 tlen
= hlen
+ sizeof(struct tcphdr
) + optlen
;
1172 * assume that the entire packet will fit in a header mbuf
1174 KASSERT(max_linkhdr
+ tlen
<= MHLEN
, ("syncache: mbuf too small"));
1177 * XXX shouldn't this reuse the mbuf if possible ?
1178 * Create the IP+TCP header from scratch.
1183 m
= m_gethdr(MB_DONTWAIT
, MT_HEADER
);
1186 m
->m_data
+= max_linkhdr
;
1188 m
->m_pkthdr
.len
= tlen
;
1189 m
->m_pkthdr
.rcvif
= NULL
;
1192 ip6
= mtod(m
, struct ip6_hdr
*);
1193 ip6
->ip6_vfc
= IPV6_VERSION
;
1194 ip6
->ip6_nxt
= IPPROTO_TCP
;
1195 ip6
->ip6_src
= sc
->sc_inc
.inc6_laddr
;
1196 ip6
->ip6_dst
= sc
->sc_inc
.inc6_faddr
;
1197 ip6
->ip6_plen
= htons(tlen
- hlen
);
1198 /* ip6_hlim is set after checksum */
1199 /* ip6_flow = ??? */
1201 th
= (struct tcphdr
*)(ip6
+ 1);
1203 ip
= mtod(m
, struct ip
*);
1204 ip
->ip_v
= IPVERSION
;
1205 ip
->ip_hl
= sizeof(struct ip
) >> 2;
1210 ip
->ip_p
= IPPROTO_TCP
;
1211 ip
->ip_src
= sc
->sc_inc
.inc_laddr
;
1212 ip
->ip_dst
= sc
->sc_inc
.inc_faddr
;
1213 ip
->ip_ttl
= sc
->sc_tp
->t_inpcb
->inp_ip_ttl
; /* XXX */
1214 ip
->ip_tos
= sc
->sc_tp
->t_inpcb
->inp_ip_tos
; /* XXX */
1217 * See if we should do MTU discovery. Route lookups are
1218 * expensive, so we will only unset the DF bit if:
1220 * 1) path_mtu_discovery is disabled
1221 * 2) the SCF_UNREACH flag has been set
1223 if (path_mtu_discovery
1224 && ((sc
->sc_flags
& SCF_UNREACH
) == 0)) {
1225 ip
->ip_off
|= IP_DF
;
1228 th
= (struct tcphdr
*)(ip
+ 1);
1230 th
->th_sport
= sc
->sc_inc
.inc_lport
;
1231 th
->th_dport
= sc
->sc_inc
.inc_fport
;
1233 th
->th_seq
= htonl(sc
->sc_iss
);
1234 th
->th_ack
= htonl(sc
->sc_irs
+ 1);
1235 th
->th_off
= (sizeof(struct tcphdr
) + optlen
) >> 2;
1237 th
->th_flags
= TH_SYN
| TH_ACK
;
1238 th
->th_win
= htons(sc
->sc_wnd
);
1241 /* Tack on the TCP options. */
1244 optp
= (u_int8_t
*)(th
+ 1);
1245 *optp
++ = TCPOPT_MAXSEG
;
1246 *optp
++ = TCPOLEN_MAXSEG
;
1247 *optp
++ = (mssopt
>> 8) & 0xff;
1248 *optp
++ = mssopt
& 0xff;
1250 if (sc
->sc_flags
& SCF_WINSCALE
) {
1251 *((u_int32_t
*)optp
) = htonl(TCPOPT_NOP
<< 24 |
1252 TCPOPT_WINDOW
<< 16 | TCPOLEN_WINDOW
<< 8 |
1253 sc
->sc_request_r_scale
);
1257 if (sc
->sc_flags
& SCF_TIMESTAMP
) {
1258 u_int32_t
*lp
= (u_int32_t
*)(optp
);
1260 /* Form timestamp option as shown in appendix A of RFC 1323. */
1261 *lp
++ = htonl(TCPOPT_TSTAMP_HDR
);
1262 *lp
++ = htonl(ticks
);
1263 *lp
= htonl(sc
->sc_tsrecent
);
1264 optp
+= TCPOLEN_TSTAMP_APPA
;
1267 #ifdef TCP_SIGNATURE
1269 * Handle TCP-MD5 passive opener response.
1271 if (sc
->sc_flags
& SCF_SIGNATURE
) {
1272 u_int8_t
*bp
= optp
;
1275 *bp
++ = TCPOPT_SIGNATURE
;
1276 *bp
++ = TCPOLEN_SIGNATURE
;
1277 for (i
= 0; i
< TCP_SIGLEN
; i
++)
1279 tcpsignature_compute(m
, 0, optlen
,
1280 optp
+ 2, IPSEC_DIR_OUTBOUND
);
1283 optp
+= TCPOLEN_SIGNATURE
+ 2;
1285 #endif /* TCP_SIGNATURE */
1287 if (sc
->sc_flags
& SCF_SACK_PERMITTED
) {
1288 *((u_int32_t
*)optp
) = htonl(TCPOPT_SACK_PERMITTED_ALIGNED
);
1289 optp
+= TCPOLEN_SACK_PERMITTED_ALIGNED
;
1294 struct route_in6
*ro6
= &sc
->sc_route6
;
1297 th
->th_sum
= in6_cksum(m
, IPPROTO_TCP
, hlen
, tlen
- hlen
);
1298 ip6
->ip6_hlim
= in6_selecthlim(NULL
,
1299 ro6
->ro_rt
? ro6
->ro_rt
->rt_ifp
: NULL
);
1300 error
= ip6_output(m
, NULL
, ro6
, 0, NULL
, NULL
,
1301 sc
->sc_tp
->t_inpcb
);
1303 th
->th_sum
= in_pseudo(ip
->ip_src
.s_addr
, ip
->ip_dst
.s_addr
,
1304 htons(tlen
- hlen
+ IPPROTO_TCP
));
1305 m
->m_pkthdr
.csum_flags
= CSUM_TCP
;
1306 m
->m_pkthdr
.csum_data
= offsetof(struct tcphdr
, th_sum
);
1307 error
= ip_output(m
, sc
->sc_ipopts
, &sc
->sc_route
,
1308 IP_DEBUGROUTE
, NULL
, sc
->sc_tp
->t_inpcb
);
1316 * |. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .|
1318 * | MD5(laddr,faddr,secret,lport,fport) |. . . . . . .|
1320 * (A): peer mss index
1324 * The values below are chosen to minimize the size of the tcp_secret
1325 * table, as well as providing roughly a 16 second lifetime for the cookie.
1328 #define SYNCOOKIE_WNDBITS 5 /* exposed bits for window indexing */
1329 #define SYNCOOKIE_TIMESHIFT 1 /* scale ticks to window time units */
1331 #define SYNCOOKIE_WNDMASK ((1 << SYNCOOKIE_WNDBITS) - 1)
1332 #define SYNCOOKIE_NSECRETS (1 << SYNCOOKIE_WNDBITS)
1333 #define SYNCOOKIE_TIMEOUT \
1334 (hz * (1 << SYNCOOKIE_WNDBITS) / (1 << SYNCOOKIE_TIMESHIFT))
1335 #define SYNCOOKIE_DATAMASK ((3 << SYNCOOKIE_WNDBITS) | SYNCOOKIE_WNDMASK)
1338 u_int32_t ts_secbits
[4];
1340 } tcp_secret
[SYNCOOKIE_NSECRETS
];
1342 static int tcp_msstab
[] = { 0, 536, 1460, 8960 };
1344 static MD5_CTX syn_ctx
;
1346 #define MD5Add(v) MD5Update(&syn_ctx, (u_char *)&v, sizeof(v))
1349 u_int32_t laddr
, faddr
;
1350 u_int32_t secbits
[4];
1351 u_int16_t lport
, fport
;
1355 CTASSERT(sizeof(struct md5_add
) == 28);
1359 * Consider the problem of a recreated (and retransmitted) cookie. If the
1360 * original SYN was accepted, the connection is established. The second
1361 * SYN is inflight, and if it arrives with an ISN that falls within the
1362 * receive window, the connection is killed.
1364 * However, since cookies have other problems, this may not be worth
1369 syncookie_generate(struct syncache
*sc
)
1371 u_int32_t md5_buffer
[4];
1376 const boolean_t isipv6
= sc
->sc_inc
.inc_isipv6
;
1378 const boolean_t isipv6
= FALSE
;
1381 idx
= ((ticks
<< SYNCOOKIE_TIMESHIFT
) / hz
) & SYNCOOKIE_WNDMASK
;
1382 if (tcp_secret
[idx
].ts_expire
< ticks
) {
1383 for (i
= 0; i
< 4; i
++)
1384 tcp_secret
[idx
].ts_secbits
[i
] = karc4random();
1385 tcp_secret
[idx
].ts_expire
= ticks
+ SYNCOOKIE_TIMEOUT
;
1387 for (data
= NELEM(tcp_msstab
) - 1; data
> 0; data
--)
1388 if (tcp_msstab
[data
] <= sc
->sc_peer_mss
)
1390 data
= (data
<< SYNCOOKIE_WNDBITS
) | idx
;
1391 data
^= sc
->sc_irs
; /* peer's iss */
1394 MD5Add(sc
->sc_inc
.inc6_laddr
);
1395 MD5Add(sc
->sc_inc
.inc6_faddr
);
1399 add
.laddr
= sc
->sc_inc
.inc_laddr
.s_addr
;
1400 add
.faddr
= sc
->sc_inc
.inc_faddr
.s_addr
;
1402 add
.lport
= sc
->sc_inc
.inc_lport
;
1403 add
.fport
= sc
->sc_inc
.inc_fport
;
1404 add
.secbits
[0] = tcp_secret
[idx
].ts_secbits
[0];
1405 add
.secbits
[1] = tcp_secret
[idx
].ts_secbits
[1];
1406 add
.secbits
[2] = tcp_secret
[idx
].ts_secbits
[2];
1407 add
.secbits
[3] = tcp_secret
[idx
].ts_secbits
[3];
1409 MD5Final((u_char
*)&md5_buffer
, &syn_ctx
);
1410 data
^= (md5_buffer
[0] & ~SYNCOOKIE_WNDMASK
);
1414 static struct syncache
*
1415 syncookie_lookup(struct in_conninfo
*inc
, struct tcphdr
*th
, struct socket
*so
)
1417 u_int32_t md5_buffer
[4];
1418 struct syncache
*sc
;
1423 data
= (th
->th_ack
- 1) ^ (th
->th_seq
- 1); /* remove ISS */
1424 idx
= data
& SYNCOOKIE_WNDMASK
;
1425 if (tcp_secret
[idx
].ts_expire
< ticks
||
1426 sototcpcb(so
)->ts_recent
+ SYNCOOKIE_TIMEOUT
< ticks
)
1430 if (inc
->inc_isipv6
) {
1431 MD5Add(inc
->inc6_laddr
);
1432 MD5Add(inc
->inc6_faddr
);
1438 add
.laddr
= inc
->inc_laddr
.s_addr
;
1439 add
.faddr
= inc
->inc_faddr
.s_addr
;
1441 add
.lport
= inc
->inc_lport
;
1442 add
.fport
= inc
->inc_fport
;
1443 add
.secbits
[0] = tcp_secret
[idx
].ts_secbits
[0];
1444 add
.secbits
[1] = tcp_secret
[idx
].ts_secbits
[1];
1445 add
.secbits
[2] = tcp_secret
[idx
].ts_secbits
[2];
1446 add
.secbits
[3] = tcp_secret
[idx
].ts_secbits
[3];
1448 MD5Final((u_char
*)&md5_buffer
, &syn_ctx
);
1449 data
^= md5_buffer
[0];
1450 if (data
& ~SYNCOOKIE_DATAMASK
)
1452 data
= data
>> SYNCOOKIE_WNDBITS
;
1455 * Fill in the syncache values.
1456 * XXX duplicate code from syncache_add
1458 sc
= kmalloc(sizeof(struct syncache
), M_SYNCACHE
, M_WAITOK
|M_ZERO
);
1459 sc
->sc_ipopts
= NULL
;
1460 sc
->sc_inc
.inc_fport
= inc
->inc_fport
;
1461 sc
->sc_inc
.inc_lport
= inc
->inc_lport
;
1463 sc
->sc_inc
.inc_isipv6
= inc
->inc_isipv6
;
1464 if (inc
->inc_isipv6
) {
1465 sc
->sc_inc
.inc6_faddr
= inc
->inc6_faddr
;
1466 sc
->sc_inc
.inc6_laddr
= inc
->inc6_laddr
;
1467 sc
->sc_route6
.ro_rt
= NULL
;
1471 sc
->sc_inc
.inc_faddr
= inc
->inc_faddr
;
1472 sc
->sc_inc
.inc_laddr
= inc
->inc_laddr
;
1473 sc
->sc_route
.ro_rt
= NULL
;
1475 sc
->sc_irs
= th
->th_seq
- 1;
1476 sc
->sc_iss
= th
->th_ack
- 1;
1477 wnd
= ssb_space(&so
->so_rcv
);
1479 wnd
= imin(wnd
, TCP_MAXWIN
);
1483 sc
->sc_peer_mss
= tcp_msstab
[data
];