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 $
72 * $DragonFly: src/sys/netinet/tcp_syncache.c,v 1.35 2008/11/22 11:03:35 sephe 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 nm_netmsg
;
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 struct tcp_syncache_percpu
{
187 struct syncache_head
*hashbase
;
189 TAILQ_HEAD(, syncache
) timerq
[SYNCACHE_MAXREXMTS
+ 1];
190 struct callout tt_timerq
[SYNCACHE_MAXREXMTS
+ 1];
191 struct msgrec mrec
[SYNCACHE_MAXREXMTS
+ 1];
193 static struct tcp_syncache_percpu tcp_syncache_percpu
[MAXCPU
];
195 static struct lwkt_port syncache_null_rport
;
197 SYSCTL_NODE(_net_inet_tcp
, OID_AUTO
, syncache
, CTLFLAG_RW
, 0, "TCP SYN cache");
199 SYSCTL_INT(_net_inet_tcp_syncache
, OID_AUTO
, bucketlimit
, CTLFLAG_RD
,
200 &tcp_syncache
.bucket_limit
, 0, "Per-bucket hash limit for syncache");
202 SYSCTL_INT(_net_inet_tcp_syncache
, OID_AUTO
, cachelimit
, CTLFLAG_RD
,
203 &tcp_syncache
.cache_limit
, 0, "Overall entry limit for syncache");
207 SYSCTL_INT(_net_inet_tcp_syncache
, OID_AUTO
, count
, CTLFLAG_RD
,
208 &tcp_syncache
.cache_count
, 0, "Current number of entries in syncache");
211 SYSCTL_INT(_net_inet_tcp_syncache
, OID_AUTO
, hashsize
, CTLFLAG_RD
,
212 &tcp_syncache
.hashsize
, 0, "Size of TCP syncache hashtable");
214 SYSCTL_INT(_net_inet_tcp_syncache
, OID_AUTO
, rexmtlimit
, CTLFLAG_RW
,
215 &tcp_syncache
.rexmt_limit
, 0, "Limit on SYN/ACK retransmissions");
217 static MALLOC_DEFINE(M_SYNCACHE
, "syncache", "TCP syncache");
219 #define SYNCACHE_HASH(inc, mask) \
220 ((tcp_syncache.hash_secret ^ \
221 (inc)->inc_faddr.s_addr ^ \
222 ((inc)->inc_faddr.s_addr >> 16) ^ \
223 (inc)->inc_fport ^ (inc)->inc_lport) & mask)
225 #define SYNCACHE_HASH6(inc, mask) \
226 ((tcp_syncache.hash_secret ^ \
227 (inc)->inc6_faddr.s6_addr32[0] ^ \
228 (inc)->inc6_faddr.s6_addr32[3] ^ \
229 (inc)->inc_fport ^ (inc)->inc_lport) & mask)
231 #define ENDPTS_EQ(a, b) ( \
232 (a)->ie_fport == (b)->ie_fport && \
233 (a)->ie_lport == (b)->ie_lport && \
234 (a)->ie_faddr.s_addr == (b)->ie_faddr.s_addr && \
235 (a)->ie_laddr.s_addr == (b)->ie_laddr.s_addr \
238 #define ENDPTS6_EQ(a, b) (memcmp(a, b, sizeof(*a)) == 0)
241 syncache_timeout(struct tcp_syncache_percpu
*syncache_percpu
,
242 struct syncache
*sc
, int slot
)
244 sc
->sc_rxtslot
= slot
;
245 sc
->sc_rxttime
= ticks
+ TCPTV_RTOBASE
* tcp_backoff
[slot
];
247 TAILQ_INSERT_TAIL(&syncache_percpu
->timerq
[slot
], sc
, sc_timerq
);
248 if (!callout_active(&syncache_percpu
->tt_timerq
[slot
])) {
249 callout_reset(&syncache_percpu
->tt_timerq
[slot
],
250 TCPTV_RTOBASE
* tcp_backoff
[slot
],
252 &syncache_percpu
->mrec
[slot
]);
258 syncache_free(struct syncache
*sc
)
262 const boolean_t isipv6
= sc
->sc_inc
.inc_isipv6
;
264 const boolean_t isipv6
= FALSE
;
268 m_free(sc
->sc_ipopts
);
270 rt
= isipv6
? sc
->sc_route6
.ro_rt
: sc
->sc_route
.ro_rt
;
273 * If this is the only reference to a protocol-cloned
274 * route, remove it immediately.
276 if ((rt
->rt_flags
& RTF_WASCLONED
) && rt
->rt_refcnt
== 1)
277 rtrequest(RTM_DELETE
, rt_key(rt
), rt
->rt_gateway
,
278 rt_mask(rt
), rt
->rt_flags
, NULL
);
281 kfree(sc
, M_SYNCACHE
);
289 tcp_syncache
.hashsize
= TCP_SYNCACHE_HASHSIZE
;
290 tcp_syncache
.bucket_limit
= TCP_SYNCACHE_BUCKETLIMIT
;
291 tcp_syncache
.cache_limit
=
292 tcp_syncache
.hashsize
* tcp_syncache
.bucket_limit
;
293 tcp_syncache
.rexmt_limit
= SYNCACHE_MAXREXMTS
;
294 tcp_syncache
.hash_secret
= karc4random();
296 TUNABLE_INT_FETCH("net.inet.tcp.syncache.hashsize",
297 &tcp_syncache
.hashsize
);
298 TUNABLE_INT_FETCH("net.inet.tcp.syncache.cachelimit",
299 &tcp_syncache
.cache_limit
);
300 TUNABLE_INT_FETCH("net.inet.tcp.syncache.bucketlimit",
301 &tcp_syncache
.bucket_limit
);
302 if (!powerof2(tcp_syncache
.hashsize
)) {
303 kprintf("WARNING: syncache hash size is not a power of 2.\n");
304 tcp_syncache
.hashsize
= 512; /* safe default */
306 tcp_syncache
.hashmask
= tcp_syncache
.hashsize
- 1;
308 lwkt_initport_replyonly_null(&syncache_null_rport
);
310 for (cpu
= 0; cpu
< ncpus2
; cpu
++) {
311 struct tcp_syncache_percpu
*syncache_percpu
;
313 syncache_percpu
= &tcp_syncache_percpu
[cpu
];
314 /* Allocate the hash table. */
315 MALLOC(syncache_percpu
->hashbase
, struct syncache_head
*,
316 tcp_syncache
.hashsize
* sizeof(struct syncache_head
),
317 M_SYNCACHE
, M_WAITOK
);
319 /* Initialize the hash buckets. */
320 for (i
= 0; i
< tcp_syncache
.hashsize
; i
++) {
321 struct syncache_head
*bucket
;
323 bucket
= &syncache_percpu
->hashbase
[i
];
324 TAILQ_INIT(&bucket
->sch_bucket
);
325 bucket
->sch_length
= 0;
328 for (i
= 0; i
<= SYNCACHE_MAXREXMTS
; i
++) {
329 /* Initialize the timer queues. */
330 TAILQ_INIT(&syncache_percpu
->timerq
[i
]);
331 callout_init(&syncache_percpu
->tt_timerq
[i
]);
333 syncache_percpu
->mrec
[i
].slot
= i
;
334 syncache_percpu
->mrec
[i
].port
= tcp_cport(cpu
);
335 syncache_percpu
->mrec
[i
].msg
.nm_mrec
=
336 &syncache_percpu
->mrec
[i
];
337 netmsg_init(&syncache_percpu
->mrec
[i
].msg
.nm_netmsg
,
338 NULL
, &syncache_null_rport
,
339 0, syncache_timer_handler
);
345 syncache_insert(struct syncache
*sc
, struct syncache_head
*sch
)
347 struct tcp_syncache_percpu
*syncache_percpu
;
348 struct syncache
*sc2
;
351 syncache_percpu
= &tcp_syncache_percpu
[mycpu
->gd_cpuid
];
354 * Make sure that we don't overflow the per-bucket
355 * limit or the total cache size limit.
357 if (sch
->sch_length
>= tcp_syncache
.bucket_limit
) {
359 * The bucket is full, toss the oldest element.
361 sc2
= TAILQ_FIRST(&sch
->sch_bucket
);
362 sc2
->sc_tp
->ts_recent
= ticks
;
363 syncache_drop(sc2
, sch
);
364 tcpstat
.tcps_sc_bucketoverflow
++;
365 } else if (syncache_percpu
->cache_count
>= tcp_syncache
.cache_limit
) {
367 * The cache is full. Toss the oldest entry in the
368 * entire cache. This is the front entry in the
369 * first non-empty timer queue with the largest
372 for (i
= SYNCACHE_MAXREXMTS
; i
>= 0; i
--) {
373 sc2
= TAILQ_FIRST(&syncache_percpu
->timerq
[i
]);
377 sc2
->sc_tp
->ts_recent
= ticks
;
378 syncache_drop(sc2
, NULL
);
379 tcpstat
.tcps_sc_cacheoverflow
++;
382 /* Initialize the entry's timer. */
383 syncache_timeout(syncache_percpu
, sc
, 0);
385 /* Put it into the bucket. */
386 TAILQ_INSERT_TAIL(&sch
->sch_bucket
, sc
, sc_hash
);
388 syncache_percpu
->cache_count
++;
389 tcpstat
.tcps_sc_added
++;
393 syncache_destroy(struct tcpcb
*tp
)
395 struct tcp_syncache_percpu
*syncache_percpu
;
396 struct syncache_head
*bucket
;
400 syncache_percpu
= &tcp_syncache_percpu
[mycpu
->gd_cpuid
];
402 for (i
= 0; i
< tcp_syncache
.hashsize
; i
++) {
403 bucket
= &syncache_percpu
->hashbase
[i
];
404 TAILQ_FOREACH(sc
, &bucket
->sch_bucket
, sc_hash
) {
405 if (sc
->sc_tp
== tp
) {
407 tp
->t_flags
&= ~TF_SYNCACHE
;
412 kprintf("Warning: delete stale syncache for tp=%p, sc=%p\n", tp
, sc
);
416 syncache_drop(struct syncache
*sc
, struct syncache_head
*sch
)
418 struct tcp_syncache_percpu
*syncache_percpu
;
420 const boolean_t isipv6
= sc
->sc_inc
.inc_isipv6
;
422 const boolean_t isipv6
= FALSE
;
425 syncache_percpu
= &tcp_syncache_percpu
[mycpu
->gd_cpuid
];
429 sch
= &syncache_percpu
->hashbase
[
430 SYNCACHE_HASH6(&sc
->sc_inc
, tcp_syncache
.hashmask
)];
432 sch
= &syncache_percpu
->hashbase
[
433 SYNCACHE_HASH(&sc
->sc_inc
, tcp_syncache
.hashmask
)];
437 TAILQ_REMOVE(&sch
->sch_bucket
, sc
, sc_hash
);
439 syncache_percpu
->cache_count
--;
445 sc
->sc_tp
->t_flags
&= ~TF_SYNCACHE
;
450 * Remove the entry from the syncache timer/timeout queue. Note
451 * that we do not try to stop any running timer since we do not know
452 * whether the timer's message is in-transit or not. Since timeouts
453 * are fairly long, taking an unneeded callout does not detrimentally
454 * effect performance.
457 TAILQ_REMOVE(&syncache_percpu
->timerq
[sc
->sc_rxtslot
], sc
, sc_timerq
);
464 * Place a timeout message on the TCP thread's message queue.
465 * This routine runs in soft interrupt context.
467 * An invariant is for this routine to be called, the callout must
468 * have been active. Note that the callout is not deactivated until
469 * after the message has been processed in syncache_timer_handler() below.
472 syncache_timer(void *p
)
474 struct netmsg_sc_timer
*msg
= p
;
476 lwkt_sendmsg(msg
->nm_mrec
->port
, &msg
->nm_netmsg
.nm_lmsg
);
480 * Service a timer message queued by timer expiration.
481 * This routine runs in the TCP protocol thread.
483 * Walk the timer queues, looking for SYN,ACKs that need to be retransmitted.
484 * If we have retransmitted an entry the maximum number of times, expire it.
486 * When we finish processing timed-out entries, we restart the timer if there
487 * are any entries still on the queue and deactivate it otherwise. Only after
488 * a timer has been deactivated here can it be restarted by syncache_timeout().
491 syncache_timer_handler(netmsg_t netmsg
)
493 struct tcp_syncache_percpu
*syncache_percpu
;
494 struct syncache
*sc
, *nsc
;
498 slot
= ((struct netmsg_sc_timer
*)netmsg
)->nm_mrec
->slot
;
499 syncache_percpu
= &tcp_syncache_percpu
[mycpu
->gd_cpuid
];
502 nsc
= TAILQ_FIRST(&syncache_percpu
->timerq
[slot
]);
503 while (nsc
!= NULL
) {
504 if (ticks
< nsc
->sc_rxttime
)
505 break; /* finished because timerq sorted by time */
507 if (sc
->sc_tp
== NULL
) {
508 nsc
= TAILQ_NEXT(sc
, sc_timerq
);
509 syncache_drop(sc
, NULL
);
510 tcpstat
.tcps_sc_stale
++;
513 inp
= sc
->sc_tp
->t_inpcb
;
514 if (slot
== SYNCACHE_MAXREXMTS
||
515 slot
>= tcp_syncache
.rexmt_limit
||
516 inp
->inp_gencnt
!= sc
->sc_inp_gencnt
) {
517 nsc
= TAILQ_NEXT(sc
, sc_timerq
);
518 syncache_drop(sc
, NULL
);
519 tcpstat
.tcps_sc_stale
++;
523 * syncache_respond() may call back into the syncache to
524 * to modify another entry, so do not obtain the next
525 * entry on the timer chain until it has completed.
527 syncache_respond(sc
, NULL
);
528 nsc
= TAILQ_NEXT(sc
, sc_timerq
);
529 tcpstat
.tcps_sc_retransmitted
++;
530 TAILQ_REMOVE(&syncache_percpu
->timerq
[slot
], sc
, sc_timerq
);
531 syncache_timeout(syncache_percpu
, sc
, slot
+ 1);
534 callout_reset(&syncache_percpu
->tt_timerq
[slot
],
535 nsc
->sc_rxttime
- ticks
, syncache_timer
,
536 &syncache_percpu
->mrec
[slot
]);
538 callout_deactivate(&syncache_percpu
->tt_timerq
[slot
]);
541 lwkt_replymsg(&netmsg
->nm_lmsg
, 0);
545 * Find an entry in the syncache.
548 syncache_lookup(struct in_conninfo
*inc
, struct syncache_head
**schp
)
550 struct tcp_syncache_percpu
*syncache_percpu
;
552 struct syncache_head
*sch
;
554 syncache_percpu
= &tcp_syncache_percpu
[mycpu
->gd_cpuid
];
556 if (inc
->inc_isipv6
) {
557 sch
= &syncache_percpu
->hashbase
[
558 SYNCACHE_HASH6(inc
, tcp_syncache
.hashmask
)];
560 TAILQ_FOREACH(sc
, &sch
->sch_bucket
, sc_hash
)
561 if (ENDPTS6_EQ(&inc
->inc_ie
, &sc
->sc_inc
.inc_ie
))
566 sch
= &syncache_percpu
->hashbase
[
567 SYNCACHE_HASH(inc
, tcp_syncache
.hashmask
)];
569 TAILQ_FOREACH(sc
, &sch
->sch_bucket
, sc_hash
) {
571 if (sc
->sc_inc
.inc_isipv6
)
574 if (ENDPTS_EQ(&inc
->inc_ie
, &sc
->sc_inc
.inc_ie
))
582 * This function is called when we get a RST for a
583 * non-existent connection, so that we can see if the
584 * connection is in the syn cache. If it is, zap it.
587 syncache_chkrst(struct in_conninfo
*inc
, struct tcphdr
*th
)
590 struct syncache_head
*sch
;
592 sc
= syncache_lookup(inc
, &sch
);
596 * If the RST bit is set, check the sequence number to see
597 * if this is a valid reset segment.
599 * In all states except SYN-SENT, all reset (RST) segments
600 * are validated by checking their SEQ-fields. A reset is
601 * valid if its sequence number is in the window.
603 * The sequence number in the reset segment is normally an
604 * echo of our outgoing acknowlegement numbers, but some hosts
605 * send a reset with the sequence number at the rightmost edge
606 * of our receive window, and we have to handle this case.
608 if (SEQ_GEQ(th
->th_seq
, sc
->sc_irs
) &&
609 SEQ_LEQ(th
->th_seq
, sc
->sc_irs
+ sc
->sc_wnd
)) {
610 syncache_drop(sc
, sch
);
611 tcpstat
.tcps_sc_reset
++;
616 syncache_badack(struct in_conninfo
*inc
)
619 struct syncache_head
*sch
;
621 sc
= syncache_lookup(inc
, &sch
);
623 syncache_drop(sc
, sch
);
624 tcpstat
.tcps_sc_badack
++;
629 syncache_unreach(struct in_conninfo
*inc
, struct tcphdr
*th
)
632 struct syncache_head
*sch
;
634 /* we are called at splnet() here */
635 sc
= syncache_lookup(inc
, &sch
);
639 /* If the sequence number != sc_iss, then it's a bogus ICMP msg */
640 if (ntohl(th
->th_seq
) != sc
->sc_iss
)
644 * If we've rertransmitted 3 times and this is our second error,
645 * we remove the entry. Otherwise, we allow it to continue on.
646 * This prevents us from incorrectly nuking an entry during a
647 * spurious network outage.
651 if ((sc
->sc_flags
& SCF_UNREACH
) == 0 || sc
->sc_rxtslot
< 3) {
652 sc
->sc_flags
|= SCF_UNREACH
;
655 syncache_drop(sc
, sch
);
656 tcpstat
.tcps_sc_unreach
++;
660 * Build a new TCP socket structure from a syncache entry.
662 * This is called from the context of the SYN+ACK
664 static struct socket
*
665 syncache_socket(struct syncache
*sc
, struct socket
*lso
, struct mbuf
*m
)
667 struct inpcb
*inp
= NULL
, *linp
;
672 const boolean_t isipv6
= sc
->sc_inc
.inc_isipv6
;
674 const boolean_t isipv6
= FALSE
;
678 * Ok, create the full blown connection, and set things up
679 * as they would have been set up if we had created the
680 * connection when the SYN arrived. If we can't create
681 * the connection, abort it.
683 so
= sonewconn(lso
, SS_ISCONNECTED
);
686 * Drop the connection; we will send a RST if the peer
687 * retransmits the ACK,
689 tcpstat
.tcps_listendrop
++;
694 * Set the protocol processing port for the socket to the current
695 * port (that the connection came in on).
697 sosetport(so
, &curthread
->td_msgport
);
700 * Insert new socket into hash list.
703 inp
->inp_inc
.inc_isipv6
= sc
->sc_inc
.inc_isipv6
;
705 inp
->in6p_laddr
= sc
->sc_inc
.inc6_laddr
;
708 inp
->inp_vflag
&= ~INP_IPV6
;
709 inp
->inp_vflag
|= INP_IPV4
;
710 inp
->inp_flags
&= ~IN6P_IPV6_V6ONLY
;
712 inp
->inp_laddr
= sc
->sc_inc
.inc_laddr
;
714 inp
->inp_lport
= sc
->sc_inc
.inc_lport
;
715 if (in_pcbinsporthash(inp
) != 0) {
717 * Undo the assignments above if we failed to
718 * put the PCB on the hash lists.
721 inp
->in6p_laddr
= kin6addr_any
;
723 inp
->inp_laddr
.s_addr
= INADDR_ANY
;
729 /* copy old policy into new socket's */
730 if (ipsec_copy_policy(linp
->inp_sp
, inp
->inp_sp
))
731 kprintf("syncache_expand: could not copy policy\n");
734 struct in6_addr laddr6
;
735 struct sockaddr_in6 sin6
;
737 * Inherit socket options from the listening socket.
738 * Note that in6p_inputopts are not (and should not be)
739 * copied, since it stores previously received options and is
740 * used to detect if each new option is different than the
741 * previous one and hence should be passed to a user.
742 * If we copied in6p_inputopts, a user would not be able to
743 * receive options just after calling the accept system call.
745 inp
->inp_flags
|= linp
->inp_flags
& INP_CONTROLOPTS
;
746 if (linp
->in6p_outputopts
)
747 inp
->in6p_outputopts
=
748 ip6_copypktopts(linp
->in6p_outputopts
, M_INTWAIT
);
749 inp
->in6p_route
= sc
->sc_route6
;
750 sc
->sc_route6
.ro_rt
= NULL
;
752 sin6
.sin6_family
= AF_INET6
;
753 sin6
.sin6_len
= sizeof sin6
;
754 sin6
.sin6_addr
= sc
->sc_inc
.inc6_faddr
;
755 sin6
.sin6_port
= sc
->sc_inc
.inc_fport
;
756 sin6
.sin6_flowinfo
= sin6
.sin6_scope_id
= 0;
757 laddr6
= inp
->in6p_laddr
;
758 if (IN6_IS_ADDR_UNSPECIFIED(&inp
->in6p_laddr
))
759 inp
->in6p_laddr
= sc
->sc_inc
.inc6_laddr
;
760 if (in6_pcbconnect(inp
, (struct sockaddr
*)&sin6
, &thread0
)) {
761 inp
->in6p_laddr
= laddr6
;
765 struct in_addr laddr
;
766 struct sockaddr_in sin
;
768 inp
->inp_options
= ip_srcroute(m
);
769 if (inp
->inp_options
== NULL
) {
770 inp
->inp_options
= sc
->sc_ipopts
;
771 sc
->sc_ipopts
= NULL
;
773 inp
->inp_route
= sc
->sc_route
;
774 sc
->sc_route
.ro_rt
= NULL
;
776 sin
.sin_family
= AF_INET
;
777 sin
.sin_len
= sizeof sin
;
778 sin
.sin_addr
= sc
->sc_inc
.inc_faddr
;
779 sin
.sin_port
= sc
->sc_inc
.inc_fport
;
780 bzero(sin
.sin_zero
, sizeof sin
.sin_zero
);
781 laddr
= inp
->inp_laddr
;
782 if (inp
->inp_laddr
.s_addr
== INADDR_ANY
)
783 inp
->inp_laddr
= sc
->sc_inc
.inc_laddr
;
784 if (in_pcbconnect(inp
, (struct sockaddr
*)&sin
, &thread0
)) {
785 inp
->inp_laddr
= laddr
;
791 * The current port should be in the context of the SYN+ACK and
792 * so should match the tcp address port.
794 * XXX we may be running on the netisr thread instead of a tcp
795 * thread, in which case port will not match
796 * curthread->td_msgport.
799 port
= tcp6_addrport();
801 port
= tcp_addrport(inp
->inp_faddr
.s_addr
, inp
->inp_fport
,
802 inp
->inp_laddr
.s_addr
, inp
->inp_lport
);
804 /*KKASSERT(port == &curthread->td_msgport);*/
807 tp
->t_state
= TCPS_SYN_RECEIVED
;
808 tp
->iss
= sc
->sc_iss
;
809 tp
->irs
= sc
->sc_irs
;
812 tp
->snd_wl1
= sc
->sc_irs
;
813 tp
->rcv_up
= sc
->sc_irs
+ 1;
814 tp
->rcv_wnd
= sc
->sc_wnd
;
815 tp
->rcv_adv
+= tp
->rcv_wnd
;
817 tp
->t_flags
= sototcpcb(lso
)->t_flags
& (TF_NOPUSH
| TF_NODELAY
);
818 if (sc
->sc_flags
& SCF_NOOPT
)
819 tp
->t_flags
|= TF_NOOPT
;
820 if (sc
->sc_flags
& SCF_WINSCALE
) {
821 tp
->t_flags
|= TF_REQ_SCALE
| TF_RCVD_SCALE
;
822 tp
->requested_s_scale
= sc
->sc_requested_s_scale
;
823 tp
->request_r_scale
= sc
->sc_request_r_scale
;
825 if (sc
->sc_flags
& SCF_TIMESTAMP
) {
826 tp
->t_flags
|= TF_REQ_TSTMP
| TF_RCVD_TSTMP
;
827 tp
->ts_recent
= sc
->sc_tsrecent
;
828 tp
->ts_recent_age
= ticks
;
830 if (sc
->sc_flags
& SCF_SACK_PERMITTED
)
831 tp
->t_flags
|= TF_SACK_PERMITTED
;
833 tcp_mss(tp
, sc
->sc_peer_mss
);
836 * If the SYN,ACK was retransmitted, reset cwnd to 1 segment.
838 if (sc
->sc_rxtslot
!= 0)
839 tp
->snd_cwnd
= tp
->t_maxseg
;
840 tcp_create_timermsg(tp
, port
);
841 tcp_callout_reset(tp
, tp
->tt_keep
, tcp_keepinit
, tcp_timer_keep
);
843 tcpstat
.tcps_accepts
++;
853 * This function gets called when we receive an ACK for a
854 * socket in the LISTEN state. We look up the connection
855 * in the syncache, and if its there, we pull it out of
856 * the cache and turn it into a full-blown connection in
857 * the SYN-RECEIVED state.
860 syncache_expand(struct in_conninfo
*inc
, struct tcphdr
*th
, struct socket
**sop
,
864 struct syncache_head
*sch
;
867 sc
= syncache_lookup(inc
, &sch
);
870 * There is no syncache entry, so see if this ACK is
871 * a returning syncookie. To do this, first:
872 * A. See if this socket has had a syncache entry dropped in
873 * the past. We don't want to accept a bogus syncookie
874 * if we've never received a SYN.
875 * B. check that the syncookie is valid. If it is, then
876 * cobble up a fake syncache entry, and return.
880 sc
= syncookie_lookup(inc
, th
, *sop
);
884 tcpstat
.tcps_sc_recvcookie
++;
888 * If seg contains an ACK, but not for our SYN/ACK, send a RST.
890 if (th
->th_ack
!= sc
->sc_iss
+ 1)
893 so
= syncache_socket(sc
, *sop
, m
);
897 /* XXXjlemon check this - is this correct? */
898 tcp_respond(NULL
, m
, m
, th
,
899 th
->th_seq
+ tlen
, (tcp_seq
)0, TH_RST
| TH_ACK
);
901 m_freem(m
); /* XXX only needed for above */
902 tcpstat
.tcps_sc_aborted
++;
904 tcpstat
.tcps_sc_completed
++;
909 syncache_drop(sc
, sch
);
915 * Given a LISTEN socket and an inbound SYN request, add
916 * this to the syn cache, and send back a segment:
917 * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK>
920 * IMPORTANT NOTE: We do _NOT_ ACK data that might accompany the SYN.
921 * Doing so would require that we hold onto the data and deliver it
922 * to the application. However, if we are the target of a SYN-flood
923 * DoS attack, an attacker could send data which would eventually
924 * consume all available buffer space if it were ACKed. By not ACKing
925 * the data, we avoid this DoS scenario.
928 syncache_add(struct in_conninfo
*inc
, struct tcpopt
*to
, struct tcphdr
*th
,
929 struct socket
**sop
, struct mbuf
*m
)
931 struct tcp_syncache_percpu
*syncache_percpu
;
934 struct syncache
*sc
= NULL
;
935 struct syncache_head
*sch
;
936 struct mbuf
*ipopts
= NULL
;
939 syncache_percpu
= &tcp_syncache_percpu
[mycpu
->gd_cpuid
];
944 * Remember the IP options, if any.
947 if (!inc
->inc_isipv6
)
949 ipopts
= ip_srcroute(m
);
952 * See if we already have an entry for this connection.
953 * If we do, resend the SYN,ACK, and reset the retransmit timer.
956 * The syncache should be re-initialized with the contents
957 * of the new SYN which may have different options.
959 sc
= syncache_lookup(inc
, &sch
);
961 tcpstat
.tcps_sc_dupsyn
++;
964 * If we were remembering a previous source route,
965 * forget it and use the new one we've been given.
968 m_free(sc
->sc_ipopts
);
969 sc
->sc_ipopts
= ipopts
;
972 * Update timestamp if present.
974 if (sc
->sc_flags
& SCF_TIMESTAMP
)
975 sc
->sc_tsrecent
= to
->to_tsval
;
977 /* Just update the TOF_SACK_PERMITTED for now. */
978 if (tcp_do_sack
&& (to
->to_flags
& TOF_SACK_PERMITTED
))
979 sc
->sc_flags
|= SCF_SACK_PERMITTED
;
981 sc
->sc_flags
&= ~SCF_SACK_PERMITTED
;
984 * PCB may have changed, pick up new values.
987 sc
->sc_tp
->t_flags
&= ~TF_SYNCACHE
;
988 tp
->t_flags
|= TF_SYNCACHE
;
991 sc
->sc_inp_gencnt
= tp
->t_inpcb
->inp_gencnt
;
992 if (syncache_respond(sc
, m
) == 0) {
994 TAILQ_REMOVE(&syncache_percpu
->timerq
[sc
->sc_rxtslot
],
997 syncache_timeout(syncache_percpu
, sc
, sc
->sc_rxtslot
);
998 tcpstat
.tcps_sndacks
++;
999 tcpstat
.tcps_sndtotal
++;
1006 * Fill in the syncache values.
1008 sc
= kmalloc(sizeof(struct syncache
), M_SYNCACHE
, M_WAITOK
|M_ZERO
);
1009 sc
->sc_inp_gencnt
= tp
->t_inpcb
->inp_gencnt
;
1010 sc
->sc_ipopts
= ipopts
;
1011 sc
->sc_inc
.inc_fport
= inc
->inc_fport
;
1012 sc
->sc_inc
.inc_lport
= inc
->inc_lport
;
1014 tp
->t_flags
|= TF_SYNCACHE
;
1016 sc
->sc_inc
.inc_isipv6
= inc
->inc_isipv6
;
1017 if (inc
->inc_isipv6
) {
1018 sc
->sc_inc
.inc6_faddr
= inc
->inc6_faddr
;
1019 sc
->sc_inc
.inc6_laddr
= inc
->inc6_laddr
;
1020 sc
->sc_route6
.ro_rt
= NULL
;
1024 sc
->sc_inc
.inc_faddr
= inc
->inc_faddr
;
1025 sc
->sc_inc
.inc_laddr
= inc
->inc_laddr
;
1026 sc
->sc_route
.ro_rt
= NULL
;
1028 sc
->sc_irs
= th
->th_seq
;
1030 sc
->sc_peer_mss
= to
->to_flags
& TOF_MSS
? to
->to_mss
: 0;
1032 sc
->sc_iss
= syncookie_generate(sc
);
1034 sc
->sc_iss
= karc4random();
1036 /* Initial receive window: clip ssb_space to [0 .. TCP_MAXWIN] */
1037 win
= ssb_space(&so
->so_rcv
);
1039 win
= imin(win
, TCP_MAXWIN
);
1042 if (tcp_do_rfc1323
) {
1044 * A timestamp received in a SYN makes
1045 * it ok to send timestamp requests and replies.
1047 if (to
->to_flags
& TOF_TS
) {
1048 sc
->sc_tsrecent
= to
->to_tsval
;
1049 sc
->sc_flags
|= SCF_TIMESTAMP
;
1051 if (to
->to_flags
& TOF_SCALE
) {
1052 int wscale
= TCP_MIN_WINSHIFT
;
1054 /* Compute proper scaling value from buffer space */
1055 while (wscale
< TCP_MAX_WINSHIFT
&&
1056 (TCP_MAXWIN
<< wscale
) < so
->so_rcv
.ssb_hiwat
) {
1059 sc
->sc_request_r_scale
= wscale
;
1060 sc
->sc_requested_s_scale
= to
->to_requested_s_scale
;
1061 sc
->sc_flags
|= SCF_WINSCALE
;
1064 if (tcp_do_sack
&& (to
->to_flags
& TOF_SACK_PERMITTED
))
1065 sc
->sc_flags
|= SCF_SACK_PERMITTED
;
1066 if (tp
->t_flags
& TF_NOOPT
)
1067 sc
->sc_flags
= SCF_NOOPT
;
1069 if (syncache_respond(sc
, m
) == 0) {
1070 syncache_insert(sc
, sch
);
1071 tcpstat
.tcps_sndacks
++;
1072 tcpstat
.tcps_sndtotal
++;
1075 tcpstat
.tcps_sc_dropped
++;
1082 syncache_respond(struct syncache
*sc
, struct mbuf
*m
)
1086 u_int16_t tlen
, hlen
, mssopt
;
1087 struct ip
*ip
= NULL
;
1090 struct ip6_hdr
*ip6
= NULL
;
1092 const boolean_t isipv6
= sc
->sc_inc
.inc_isipv6
;
1094 const boolean_t isipv6
= FALSE
;
1098 rt
= tcp_rtlookup6(&sc
->sc_inc
);
1100 mssopt
= rt
->rt_ifp
->if_mtu
-
1101 (sizeof(struct ip6_hdr
) + sizeof(struct tcphdr
));
1103 mssopt
= tcp_v6mssdflt
;
1104 hlen
= sizeof(struct ip6_hdr
);
1106 rt
= tcp_rtlookup(&sc
->sc_inc
);
1108 mssopt
= rt
->rt_ifp
->if_mtu
-
1109 (sizeof(struct ip
) + sizeof(struct tcphdr
));
1111 mssopt
= tcp_mssdflt
;
1112 hlen
= sizeof(struct ip
);
1115 /* Compute the size of the TCP options. */
1116 if (sc
->sc_flags
& SCF_NOOPT
) {
1119 optlen
= TCPOLEN_MAXSEG
+
1120 ((sc
->sc_flags
& SCF_WINSCALE
) ? 4 : 0) +
1121 ((sc
->sc_flags
& SCF_TIMESTAMP
) ? TCPOLEN_TSTAMP_APPA
: 0) +
1122 ((sc
->sc_flags
& SCF_SACK_PERMITTED
) ?
1123 TCPOLEN_SACK_PERMITTED_ALIGNED
: 0);
1125 tlen
= hlen
+ sizeof(struct tcphdr
) + optlen
;
1129 * assume that the entire packet will fit in a header mbuf
1131 KASSERT(max_linkhdr
+ tlen
<= MHLEN
, ("syncache: mbuf too small"));
1134 * XXX shouldn't this reuse the mbuf if possible ?
1135 * Create the IP+TCP header from scratch.
1140 m
= m_gethdr(MB_DONTWAIT
, MT_HEADER
);
1143 m
->m_data
+= max_linkhdr
;
1145 m
->m_pkthdr
.len
= tlen
;
1146 m
->m_pkthdr
.rcvif
= NULL
;
1149 ip6
= mtod(m
, struct ip6_hdr
*);
1150 ip6
->ip6_vfc
= IPV6_VERSION
;
1151 ip6
->ip6_nxt
= IPPROTO_TCP
;
1152 ip6
->ip6_src
= sc
->sc_inc
.inc6_laddr
;
1153 ip6
->ip6_dst
= sc
->sc_inc
.inc6_faddr
;
1154 ip6
->ip6_plen
= htons(tlen
- hlen
);
1155 /* ip6_hlim is set after checksum */
1156 /* ip6_flow = ??? */
1158 th
= (struct tcphdr
*)(ip6
+ 1);
1160 ip
= mtod(m
, struct ip
*);
1161 ip
->ip_v
= IPVERSION
;
1162 ip
->ip_hl
= sizeof(struct ip
) >> 2;
1167 ip
->ip_p
= IPPROTO_TCP
;
1168 ip
->ip_src
= sc
->sc_inc
.inc_laddr
;
1169 ip
->ip_dst
= sc
->sc_inc
.inc_faddr
;
1170 ip
->ip_ttl
= sc
->sc_tp
->t_inpcb
->inp_ip_ttl
; /* XXX */
1171 ip
->ip_tos
= sc
->sc_tp
->t_inpcb
->inp_ip_tos
; /* XXX */
1174 * See if we should do MTU discovery. Route lookups are
1175 * expensive, so we will only unset the DF bit if:
1177 * 1) path_mtu_discovery is disabled
1178 * 2) the SCF_UNREACH flag has been set
1180 if (path_mtu_discovery
1181 && ((sc
->sc_flags
& SCF_UNREACH
) == 0)) {
1182 ip
->ip_off
|= IP_DF
;
1185 th
= (struct tcphdr
*)(ip
+ 1);
1187 th
->th_sport
= sc
->sc_inc
.inc_lport
;
1188 th
->th_dport
= sc
->sc_inc
.inc_fport
;
1190 th
->th_seq
= htonl(sc
->sc_iss
);
1191 th
->th_ack
= htonl(sc
->sc_irs
+ 1);
1192 th
->th_off
= (sizeof(struct tcphdr
) + optlen
) >> 2;
1194 th
->th_flags
= TH_SYN
| TH_ACK
;
1195 th
->th_win
= htons(sc
->sc_wnd
);
1198 /* Tack on the TCP options. */
1201 optp
= (u_int8_t
*)(th
+ 1);
1202 *optp
++ = TCPOPT_MAXSEG
;
1203 *optp
++ = TCPOLEN_MAXSEG
;
1204 *optp
++ = (mssopt
>> 8) & 0xff;
1205 *optp
++ = mssopt
& 0xff;
1207 if (sc
->sc_flags
& SCF_WINSCALE
) {
1208 *((u_int32_t
*)optp
) = htonl(TCPOPT_NOP
<< 24 |
1209 TCPOPT_WINDOW
<< 16 | TCPOLEN_WINDOW
<< 8 |
1210 sc
->sc_request_r_scale
);
1214 if (sc
->sc_flags
& SCF_TIMESTAMP
) {
1215 u_int32_t
*lp
= (u_int32_t
*)(optp
);
1217 /* Form timestamp option as shown in appendix A of RFC 1323. */
1218 *lp
++ = htonl(TCPOPT_TSTAMP_HDR
);
1219 *lp
++ = htonl(ticks
);
1220 *lp
= htonl(sc
->sc_tsrecent
);
1221 optp
+= TCPOLEN_TSTAMP_APPA
;
1224 if (sc
->sc_flags
& SCF_SACK_PERMITTED
) {
1225 *((u_int32_t
*)optp
) = htonl(TCPOPT_SACK_PERMITTED_ALIGNED
);
1226 optp
+= TCPOLEN_SACK_PERMITTED_ALIGNED
;
1231 struct route_in6
*ro6
= &sc
->sc_route6
;
1234 th
->th_sum
= in6_cksum(m
, IPPROTO_TCP
, hlen
, tlen
- hlen
);
1235 ip6
->ip6_hlim
= in6_selecthlim(NULL
,
1236 ro6
->ro_rt
? ro6
->ro_rt
->rt_ifp
: NULL
);
1237 error
= ip6_output(m
, NULL
, ro6
, 0, NULL
, NULL
,
1238 sc
->sc_tp
->t_inpcb
);
1240 th
->th_sum
= in_pseudo(ip
->ip_src
.s_addr
, ip
->ip_dst
.s_addr
,
1241 htons(tlen
- hlen
+ IPPROTO_TCP
));
1242 m
->m_pkthdr
.csum_flags
= CSUM_TCP
;
1243 m
->m_pkthdr
.csum_data
= offsetof(struct tcphdr
, th_sum
);
1244 error
= ip_output(m
, sc
->sc_ipopts
, &sc
->sc_route
,
1245 IP_DEBUGROUTE
, NULL
, sc
->sc_tp
->t_inpcb
);
1253 * |. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .|
1255 * | MD5(laddr,faddr,secret,lport,fport) |. . . . . . .|
1257 * (A): peer mss index
1261 * The values below are chosen to minimize the size of the tcp_secret
1262 * table, as well as providing roughly a 16 second lifetime for the cookie.
1265 #define SYNCOOKIE_WNDBITS 5 /* exposed bits for window indexing */
1266 #define SYNCOOKIE_TIMESHIFT 1 /* scale ticks to window time units */
1268 #define SYNCOOKIE_WNDMASK ((1 << SYNCOOKIE_WNDBITS) - 1)
1269 #define SYNCOOKIE_NSECRETS (1 << SYNCOOKIE_WNDBITS)
1270 #define SYNCOOKIE_TIMEOUT \
1271 (hz * (1 << SYNCOOKIE_WNDBITS) / (1 << SYNCOOKIE_TIMESHIFT))
1272 #define SYNCOOKIE_DATAMASK ((3 << SYNCOOKIE_WNDBITS) | SYNCOOKIE_WNDMASK)
1275 u_int32_t ts_secbits
[4];
1277 } tcp_secret
[SYNCOOKIE_NSECRETS
];
1279 static int tcp_msstab
[] = { 0, 536, 1460, 8960 };
1281 static MD5_CTX syn_ctx
;
1283 #define MD5Add(v) MD5Update(&syn_ctx, (u_char *)&v, sizeof(v))
1286 u_int32_t laddr
, faddr
;
1287 u_int32_t secbits
[4];
1288 u_int16_t lport
, fport
;
1292 CTASSERT(sizeof(struct md5_add
) == 28);
1296 * Consider the problem of a recreated (and retransmitted) cookie. If the
1297 * original SYN was accepted, the connection is established. The second
1298 * SYN is inflight, and if it arrives with an ISN that falls within the
1299 * receive window, the connection is killed.
1301 * However, since cookies have other problems, this may not be worth
1306 syncookie_generate(struct syncache
*sc
)
1308 u_int32_t md5_buffer
[4];
1313 const boolean_t isipv6
= sc
->sc_inc
.inc_isipv6
;
1315 const boolean_t isipv6
= FALSE
;
1318 idx
= ((ticks
<< SYNCOOKIE_TIMESHIFT
) / hz
) & SYNCOOKIE_WNDMASK
;
1319 if (tcp_secret
[idx
].ts_expire
< ticks
) {
1320 for (i
= 0; i
< 4; i
++)
1321 tcp_secret
[idx
].ts_secbits
[i
] = karc4random();
1322 tcp_secret
[idx
].ts_expire
= ticks
+ SYNCOOKIE_TIMEOUT
;
1324 for (data
= sizeof(tcp_msstab
) / sizeof(int) - 1; data
> 0; data
--)
1325 if (tcp_msstab
[data
] <= sc
->sc_peer_mss
)
1327 data
= (data
<< SYNCOOKIE_WNDBITS
) | idx
;
1328 data
^= sc
->sc_irs
; /* peer's iss */
1331 MD5Add(sc
->sc_inc
.inc6_laddr
);
1332 MD5Add(sc
->sc_inc
.inc6_faddr
);
1336 add
.laddr
= sc
->sc_inc
.inc_laddr
.s_addr
;
1337 add
.faddr
= sc
->sc_inc
.inc_faddr
.s_addr
;
1339 add
.lport
= sc
->sc_inc
.inc_lport
;
1340 add
.fport
= sc
->sc_inc
.inc_fport
;
1341 add
.secbits
[0] = tcp_secret
[idx
].ts_secbits
[0];
1342 add
.secbits
[1] = tcp_secret
[idx
].ts_secbits
[1];
1343 add
.secbits
[2] = tcp_secret
[idx
].ts_secbits
[2];
1344 add
.secbits
[3] = tcp_secret
[idx
].ts_secbits
[3];
1346 MD5Final((u_char
*)&md5_buffer
, &syn_ctx
);
1347 data
^= (md5_buffer
[0] & ~SYNCOOKIE_WNDMASK
);
1351 static struct syncache
*
1352 syncookie_lookup(struct in_conninfo
*inc
, struct tcphdr
*th
, struct socket
*so
)
1354 u_int32_t md5_buffer
[4];
1355 struct syncache
*sc
;
1360 data
= (th
->th_ack
- 1) ^ (th
->th_seq
- 1); /* remove ISS */
1361 idx
= data
& SYNCOOKIE_WNDMASK
;
1362 if (tcp_secret
[idx
].ts_expire
< ticks
||
1363 sototcpcb(so
)->ts_recent
+ SYNCOOKIE_TIMEOUT
< ticks
)
1367 if (inc
->inc_isipv6
) {
1368 MD5Add(inc
->inc6_laddr
);
1369 MD5Add(inc
->inc6_faddr
);
1375 add
.laddr
= inc
->inc_laddr
.s_addr
;
1376 add
.faddr
= inc
->inc_faddr
.s_addr
;
1378 add
.lport
= inc
->inc_lport
;
1379 add
.fport
= inc
->inc_fport
;
1380 add
.secbits
[0] = tcp_secret
[idx
].ts_secbits
[0];
1381 add
.secbits
[1] = tcp_secret
[idx
].ts_secbits
[1];
1382 add
.secbits
[2] = tcp_secret
[idx
].ts_secbits
[2];
1383 add
.secbits
[3] = tcp_secret
[idx
].ts_secbits
[3];
1385 MD5Final((u_char
*)&md5_buffer
, &syn_ctx
);
1386 data
^= md5_buffer
[0];
1387 if (data
& ~SYNCOOKIE_DATAMASK
)
1389 data
= data
>> SYNCOOKIE_WNDBITS
;
1392 * Fill in the syncache values.
1393 * XXX duplicate code from syncache_add
1395 sc
= kmalloc(sizeof(struct syncache
), M_SYNCACHE
, M_WAITOK
|M_ZERO
);
1396 sc
->sc_ipopts
= NULL
;
1397 sc
->sc_inc
.inc_fport
= inc
->inc_fport
;
1398 sc
->sc_inc
.inc_lport
= inc
->inc_lport
;
1400 sc
->sc_inc
.inc_isipv6
= inc
->inc_isipv6
;
1401 if (inc
->inc_isipv6
) {
1402 sc
->sc_inc
.inc6_faddr
= inc
->inc6_faddr
;
1403 sc
->sc_inc
.inc6_laddr
= inc
->inc6_laddr
;
1404 sc
->sc_route6
.ro_rt
= NULL
;
1408 sc
->sc_inc
.inc_faddr
= inc
->inc_faddr
;
1409 sc
->sc_inc
.inc_laddr
= inc
->inc_laddr
;
1410 sc
->sc_route
.ro_rt
= NULL
;
1412 sc
->sc_irs
= th
->th_seq
- 1;
1413 sc
->sc_iss
= th
->th_ack
- 1;
1414 wnd
= ssb_space(&so
->so_rcv
);
1416 wnd
= imin(wnd
, TCP_MAXWIN
);
1420 sc
->sc_peer_mss
= tcp_msstab
[data
];