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 $
76 #include "opt_inet6.h"
77 #include "opt_ipsec.h"
79 #include <sys/param.h>
80 #include <sys/systm.h>
81 #include <sys/kernel.h>
82 #include <sys/sysctl.h>
83 #include <sys/malloc.h>
86 #include <sys/proc.h> /* for proc0 declaration */
87 #include <sys/random.h>
88 #include <sys/socket.h>
89 #include <sys/socketvar.h>
90 #include <sys/in_cksum.h>
92 #include <sys/msgport2.h>
93 #include <net/netmsg2.h>
96 #include <net/route.h>
98 #include <netinet/in.h>
99 #include <netinet/in_systm.h>
100 #include <netinet/ip.h>
101 #include <netinet/in_var.h>
102 #include <netinet/in_pcb.h>
103 #include <netinet/ip_var.h>
104 #include <netinet/ip6.h>
106 #include <netinet/icmp6.h>
107 #include <netinet6/nd6.h>
109 #include <netinet6/ip6_var.h>
110 #include <netinet6/in6_pcb.h>
111 #include <netinet/tcp.h>
112 #include <netinet/tcp_fsm.h>
113 #include <netinet/tcp_seq.h>
114 #include <netinet/tcp_timer.h>
115 #include <netinet/tcp_timer2.h>
116 #include <netinet/tcp_var.h>
117 #include <netinet6/tcp6_var.h>
120 #include <netinet6/ipsec.h>
122 #include <netinet6/ipsec6.h>
124 #include <netproto/key/key.h>
128 #include <netproto/ipsec/ipsec.h>
130 #include <netproto/ipsec/ipsec6.h>
132 #include <netproto/ipsec/key.h>
134 #endif /*FAST_IPSEC*/
136 static int tcp_syncookies
= 1;
137 SYSCTL_INT(_net_inet_tcp
, OID_AUTO
, syncookies
, CTLFLAG_RW
,
139 "Use TCP SYN cookies if the syncache overflows");
141 static void syncache_drop(struct syncache
*, struct syncache_head
*);
142 static void syncache_free(struct syncache
*);
143 static void syncache_insert(struct syncache
*, struct syncache_head
*);
144 struct syncache
*syncache_lookup(struct in_conninfo
*, struct syncache_head
**);
145 static int syncache_respond(struct syncache
*, struct mbuf
*);
146 static struct socket
*syncache_socket(struct syncache
*, struct socket
*,
148 static void syncache_timer(void *);
149 static u_int32_t
syncookie_generate(struct syncache
*);
150 static struct syncache
*syncookie_lookup(struct in_conninfo
*,
151 struct tcphdr
*, struct socket
*);
154 * Transmit the SYN,ACK fewer times than TCP_MAXRXTSHIFT specifies.
155 * 3 retransmits corresponds to a timeout of (1 + 2 + 4 + 8 == 15) seconds,
156 * the odds are that the user has given up attempting to connect by then.
158 #define SYNCACHE_MAXREXMTS 3
160 /* Arbitrary values */
161 #define TCP_SYNCACHE_HASHSIZE 512
162 #define TCP_SYNCACHE_BUCKETLIMIT 30
164 struct netmsg_sc_timer
{
165 struct netmsg nm_netmsg
;
166 struct msgrec
*nm_mrec
; /* back pointer to containing msgrec */
170 struct netmsg_sc_timer msg
;
171 lwkt_port_t port
; /* constant after init */
172 int slot
; /* constant after init */
175 static void syncache_timer_handler(netmsg_t
);
177 struct tcp_syncache
{
185 static struct tcp_syncache tcp_syncache
;
187 TAILQ_HEAD(syncache_list
, syncache
);
189 struct tcp_syncache_percpu
{
190 struct syncache_head
*hashbase
;
192 struct syncache_list timerq
[SYNCACHE_MAXREXMTS
+ 1];
193 struct callout tt_timerq
[SYNCACHE_MAXREXMTS
+ 1];
194 struct msgrec mrec
[SYNCACHE_MAXREXMTS
+ 1];
196 static struct tcp_syncache_percpu tcp_syncache_percpu
[MAXCPU
];
198 static struct lwkt_port syncache_null_rport
;
200 SYSCTL_NODE(_net_inet_tcp
, OID_AUTO
, syncache
, CTLFLAG_RW
, 0, "TCP SYN cache");
202 SYSCTL_INT(_net_inet_tcp_syncache
, OID_AUTO
, bucketlimit
, CTLFLAG_RD
,
203 &tcp_syncache
.bucket_limit
, 0, "Per-bucket hash limit for syncache");
205 SYSCTL_INT(_net_inet_tcp_syncache
, OID_AUTO
, cachelimit
, CTLFLAG_RD
,
206 &tcp_syncache
.cache_limit
, 0, "Overall entry limit for syncache");
210 SYSCTL_INT(_net_inet_tcp_syncache
, OID_AUTO
, count
, CTLFLAG_RD
,
211 &tcp_syncache
.cache_count
, 0, "Current number of entries in syncache");
214 SYSCTL_INT(_net_inet_tcp_syncache
, OID_AUTO
, hashsize
, CTLFLAG_RD
,
215 &tcp_syncache
.hashsize
, 0, "Size of TCP syncache hashtable");
217 SYSCTL_INT(_net_inet_tcp_syncache
, OID_AUTO
, rexmtlimit
, CTLFLAG_RW
,
218 &tcp_syncache
.rexmt_limit
, 0, "Limit on SYN/ACK retransmissions");
220 static MALLOC_DEFINE(M_SYNCACHE
, "syncache", "TCP syncache");
222 #define SYNCACHE_HASH(inc, mask) \
223 ((tcp_syncache.hash_secret ^ \
224 (inc)->inc_faddr.s_addr ^ \
225 ((inc)->inc_faddr.s_addr >> 16) ^ \
226 (inc)->inc_fport ^ (inc)->inc_lport) & mask)
228 #define SYNCACHE_HASH6(inc, mask) \
229 ((tcp_syncache.hash_secret ^ \
230 (inc)->inc6_faddr.s6_addr32[0] ^ \
231 (inc)->inc6_faddr.s6_addr32[3] ^ \
232 (inc)->inc_fport ^ (inc)->inc_lport) & mask)
234 #define ENDPTS_EQ(a, b) ( \
235 (a)->ie_fport == (b)->ie_fport && \
236 (a)->ie_lport == (b)->ie_lport && \
237 (a)->ie_faddr.s_addr == (b)->ie_faddr.s_addr && \
238 (a)->ie_laddr.s_addr == (b)->ie_laddr.s_addr \
241 #define ENDPTS6_EQ(a, b) (memcmp(a, b, sizeof(*a)) == 0)
244 syncache_timeout(struct tcp_syncache_percpu
*syncache_percpu
,
245 struct syncache
*sc
, int slot
)
247 sc
->sc_rxtslot
= slot
;
248 sc
->sc_rxttime
= ticks
+ TCPTV_RTOBASE
* tcp_backoff
[slot
];
249 TAILQ_INSERT_TAIL(&syncache_percpu
->timerq
[slot
], sc
, sc_timerq
);
250 if (!callout_active(&syncache_percpu
->tt_timerq
[slot
])) {
251 callout_reset(&syncache_percpu
->tt_timerq
[slot
],
252 TCPTV_RTOBASE
* tcp_backoff
[slot
],
254 &syncache_percpu
->mrec
[slot
]);
259 syncache_free(struct syncache
*sc
)
263 const boolean_t isipv6
= sc
->sc_inc
.inc_isipv6
;
265 const boolean_t isipv6
= FALSE
;
269 m_free(sc
->sc_ipopts
);
271 rt
= isipv6
? sc
->sc_route6
.ro_rt
: sc
->sc_route
.ro_rt
;
274 * If this is the only reference to a protocol-cloned
275 * route, remove it immediately.
277 if ((rt
->rt_flags
& RTF_WASCLONED
) && rt
->rt_refcnt
== 1)
278 rtrequest(RTM_DELETE
, rt_key(rt
), rt
->rt_gateway
,
279 rt_mask(rt
), rt
->rt_flags
, NULL
);
282 kfree(sc
, M_SYNCACHE
);
290 tcp_syncache
.hashsize
= TCP_SYNCACHE_HASHSIZE
;
291 tcp_syncache
.bucket_limit
= TCP_SYNCACHE_BUCKETLIMIT
;
292 tcp_syncache
.cache_limit
=
293 tcp_syncache
.hashsize
* tcp_syncache
.bucket_limit
;
294 tcp_syncache
.rexmt_limit
= SYNCACHE_MAXREXMTS
;
295 tcp_syncache
.hash_secret
= karc4random();
297 TUNABLE_INT_FETCH("net.inet.tcp.syncache.hashsize",
298 &tcp_syncache
.hashsize
);
299 TUNABLE_INT_FETCH("net.inet.tcp.syncache.cachelimit",
300 &tcp_syncache
.cache_limit
);
301 TUNABLE_INT_FETCH("net.inet.tcp.syncache.bucketlimit",
302 &tcp_syncache
.bucket_limit
);
303 if (!powerof2(tcp_syncache
.hashsize
)) {
304 kprintf("WARNING: syncache hash size is not a power of 2.\n");
305 tcp_syncache
.hashsize
= 512; /* safe default */
307 tcp_syncache
.hashmask
= tcp_syncache
.hashsize
- 1;
309 lwkt_initport_replyonly_null(&syncache_null_rport
);
311 for (cpu
= 0; cpu
< ncpus2
; cpu
++) {
312 struct tcp_syncache_percpu
*syncache_percpu
;
314 syncache_percpu
= &tcp_syncache_percpu
[cpu
];
315 /* Allocate the hash table. */
316 MALLOC(syncache_percpu
->hashbase
, struct syncache_head
*,
317 tcp_syncache
.hashsize
* sizeof(struct syncache_head
),
318 M_SYNCACHE
, M_WAITOK
);
320 /* Initialize the hash buckets. */
321 for (i
= 0; i
< tcp_syncache
.hashsize
; i
++) {
322 struct syncache_head
*bucket
;
324 bucket
= &syncache_percpu
->hashbase
[i
];
325 TAILQ_INIT(&bucket
->sch_bucket
);
326 bucket
->sch_length
= 0;
329 for (i
= 0; i
<= SYNCACHE_MAXREXMTS
; i
++) {
330 /* Initialize the timer queues. */
331 TAILQ_INIT(&syncache_percpu
->timerq
[i
]);
332 callout_init(&syncache_percpu
->tt_timerq
[i
]);
334 syncache_percpu
->mrec
[i
].slot
= i
;
335 syncache_percpu
->mrec
[i
].port
= tcp_cport(cpu
);
336 syncache_percpu
->mrec
[i
].msg
.nm_mrec
=
337 &syncache_percpu
->mrec
[i
];
338 netmsg_init(&syncache_percpu
->mrec
[i
].msg
.nm_netmsg
,
339 NULL
, &syncache_null_rport
,
340 0, syncache_timer_handler
);
346 syncache_insert(struct syncache
*sc
, struct syncache_head
*sch
)
348 struct tcp_syncache_percpu
*syncache_percpu
;
349 struct syncache
*sc2
;
352 syncache_percpu
= &tcp_syncache_percpu
[mycpu
->gd_cpuid
];
355 * Make sure that we don't overflow the per-bucket
356 * limit or the total cache size limit.
358 if (sch
->sch_length
>= tcp_syncache
.bucket_limit
) {
360 * The bucket is full, toss the oldest element.
362 sc2
= TAILQ_FIRST(&sch
->sch_bucket
);
363 sc2
->sc_tp
->ts_recent
= ticks
;
364 syncache_drop(sc2
, sch
);
365 tcpstat
.tcps_sc_bucketoverflow
++;
366 } else if (syncache_percpu
->cache_count
>= tcp_syncache
.cache_limit
) {
368 * The cache is full. Toss the oldest entry in the
369 * entire cache. This is the front entry in the
370 * first non-empty timer queue with the largest
373 for (i
= SYNCACHE_MAXREXMTS
; i
>= 0; i
--) {
374 sc2
= TAILQ_FIRST(&syncache_percpu
->timerq
[i
]);
375 while (sc2
&& (sc2
->sc_flags
& SCF_MARKER
))
376 sc2
= TAILQ_NEXT(sc2
, sc_timerq
);
380 sc2
->sc_tp
->ts_recent
= ticks
;
381 syncache_drop(sc2
, NULL
);
382 tcpstat
.tcps_sc_cacheoverflow
++;
385 /* Initialize the entry's timer. */
386 syncache_timeout(syncache_percpu
, sc
, 0);
388 /* Put it into the bucket. */
389 TAILQ_INSERT_TAIL(&sch
->sch_bucket
, sc
, sc_hash
);
391 syncache_percpu
->cache_count
++;
392 tcpstat
.tcps_sc_added
++;
396 syncache_destroy(struct tcpcb
*tp
)
398 struct tcp_syncache_percpu
*syncache_percpu
;
399 struct syncache_head
*bucket
;
403 syncache_percpu
= &tcp_syncache_percpu
[mycpu
->gd_cpuid
];
406 for (i
= 0; i
< tcp_syncache
.hashsize
; i
++) {
407 bucket
= &syncache_percpu
->hashbase
[i
];
408 TAILQ_FOREACH(sc
, &bucket
->sch_bucket
, sc_hash
) {
409 if (sc
->sc_tp
== tp
) {
411 tp
->t_flags
&= ~TF_SYNCACHE
;
416 kprintf("Warning: delete stale syncache for tp=%p, sc=%p\n", tp
, sc
);
420 syncache_drop(struct syncache
*sc
, struct syncache_head
*sch
)
422 struct tcp_syncache_percpu
*syncache_percpu
;
424 const boolean_t isipv6
= sc
->sc_inc
.inc_isipv6
;
426 const boolean_t isipv6
= FALSE
;
429 syncache_percpu
= &tcp_syncache_percpu
[mycpu
->gd_cpuid
];
433 sch
= &syncache_percpu
->hashbase
[
434 SYNCACHE_HASH6(&sc
->sc_inc
, tcp_syncache
.hashmask
)];
436 sch
= &syncache_percpu
->hashbase
[
437 SYNCACHE_HASH(&sc
->sc_inc
, tcp_syncache
.hashmask
)];
441 TAILQ_REMOVE(&sch
->sch_bucket
, sc
, sc_hash
);
443 syncache_percpu
->cache_count
--;
449 sc
->sc_tp
->t_flags
&= ~TF_SYNCACHE
;
454 * Remove the entry from the syncache timer/timeout queue. Note
455 * that we do not try to stop any running timer since we do not know
456 * whether the timer's message is in-transit or not. Since timeouts
457 * are fairly long, taking an unneeded callout does not detrimentally
458 * effect performance.
460 TAILQ_REMOVE(&syncache_percpu
->timerq
[sc
->sc_rxtslot
], sc
, sc_timerq
);
466 * Place a timeout message on the TCP thread's message queue.
467 * This routine runs in soft interrupt context.
469 * An invariant is for this routine to be called, the callout must
470 * have been active. Note that the callout is not deactivated until
471 * after the message has been processed in syncache_timer_handler() below.
474 syncache_timer(void *p
)
476 struct netmsg_sc_timer
*msg
= p
;
478 lwkt_sendmsg(msg
->nm_mrec
->port
, &msg
->nm_netmsg
.nm_lmsg
);
482 * Service a timer message queued by timer expiration.
483 * This routine runs in the TCP protocol thread.
485 * Walk the timer queues, looking for SYN,ACKs that need to be retransmitted.
486 * If we have retransmitted an entry the maximum number of times, expire it.
488 * When we finish processing timed-out entries, we restart the timer if there
489 * are any entries still on the queue and deactivate it otherwise. Only after
490 * a timer has been deactivated here can it be restarted by syncache_timeout().
493 syncache_timer_handler(netmsg_t netmsg
)
495 struct tcp_syncache_percpu
*syncache_percpu
;
497 struct syncache marker
;
498 struct syncache_list
*list
;
502 slot
= ((struct netmsg_sc_timer
*)netmsg
)->nm_mrec
->slot
;
503 syncache_percpu
= &tcp_syncache_percpu
[mycpu
->gd_cpuid
];
505 list
= &syncache_percpu
->timerq
[slot
];
508 * Use a marker to keep our place in the scan. syncache_drop()
509 * can block and cause any next pointer we cache to become stale.
511 marker
.sc_flags
= SCF_MARKER
;
512 TAILQ_INSERT_HEAD(list
, &marker
, sc_timerq
);
514 while ((sc
= TAILQ_NEXT(&marker
, sc_timerq
)) != NULL
) {
518 TAILQ_REMOVE(list
, &marker
, sc_timerq
);
519 TAILQ_INSERT_AFTER(list
, sc
, &marker
, sc_timerq
);
521 if (sc
->sc_flags
& SCF_MARKER
)
524 if (ticks
< sc
->sc_rxttime
)
525 break; /* finished because timerq sorted by time */
526 if (sc
->sc_tp
== NULL
) {
527 syncache_drop(sc
, NULL
);
528 tcpstat
.tcps_sc_stale
++;
531 inp
= sc
->sc_tp
->t_inpcb
;
532 if (slot
== SYNCACHE_MAXREXMTS
||
533 slot
>= tcp_syncache
.rexmt_limit
||
535 inp
->inp_gencnt
!= sc
->sc_inp_gencnt
) {
536 syncache_drop(sc
, NULL
);
537 tcpstat
.tcps_sc_stale
++;
541 * syncache_respond() may call back into the syncache to
542 * to modify another entry, so do not obtain the next
543 * entry on the timer chain until it has completed.
545 syncache_respond(sc
, NULL
);
546 tcpstat
.tcps_sc_retransmitted
++;
547 TAILQ_REMOVE(list
, sc
, sc_timerq
);
548 syncache_timeout(syncache_percpu
, sc
, slot
+ 1);
550 TAILQ_REMOVE(list
, &marker
, sc_timerq
);
553 callout_reset(&syncache_percpu
->tt_timerq
[slot
],
554 sc
->sc_rxttime
- ticks
, syncache_timer
,
555 &syncache_percpu
->mrec
[slot
]);
557 callout_deactivate(&syncache_percpu
->tt_timerq
[slot
]);
559 lwkt_replymsg(&netmsg
->nm_lmsg
, 0);
563 * Find an entry in the syncache.
566 syncache_lookup(struct in_conninfo
*inc
, struct syncache_head
**schp
)
568 struct tcp_syncache_percpu
*syncache_percpu
;
570 struct syncache_head
*sch
;
572 syncache_percpu
= &tcp_syncache_percpu
[mycpu
->gd_cpuid
];
574 if (inc
->inc_isipv6
) {
575 sch
= &syncache_percpu
->hashbase
[
576 SYNCACHE_HASH6(inc
, tcp_syncache
.hashmask
)];
578 TAILQ_FOREACH(sc
, &sch
->sch_bucket
, sc_hash
)
579 if (ENDPTS6_EQ(&inc
->inc_ie
, &sc
->sc_inc
.inc_ie
))
584 sch
= &syncache_percpu
->hashbase
[
585 SYNCACHE_HASH(inc
, tcp_syncache
.hashmask
)];
587 TAILQ_FOREACH(sc
, &sch
->sch_bucket
, sc_hash
) {
589 if (sc
->sc_inc
.inc_isipv6
)
592 if (ENDPTS_EQ(&inc
->inc_ie
, &sc
->sc_inc
.inc_ie
))
600 * This function is called when we get a RST for a
601 * non-existent connection, so that we can see if the
602 * connection is in the syn cache. If it is, zap it.
605 syncache_chkrst(struct in_conninfo
*inc
, struct tcphdr
*th
)
608 struct syncache_head
*sch
;
610 sc
= syncache_lookup(inc
, &sch
);
615 * If the RST bit is set, check the sequence number to see
616 * if this is a valid reset segment.
618 * In all states except SYN-SENT, all reset (RST) segments
619 * are validated by checking their SEQ-fields. A reset is
620 * valid if its sequence number is in the window.
622 * The sequence number in the reset segment is normally an
623 * echo of our outgoing acknowlegement numbers, but some hosts
624 * send a reset with the sequence number at the rightmost edge
625 * of our receive window, and we have to handle this case.
627 if (SEQ_GEQ(th
->th_seq
, sc
->sc_irs
) &&
628 SEQ_LEQ(th
->th_seq
, sc
->sc_irs
+ sc
->sc_wnd
)) {
629 syncache_drop(sc
, sch
);
630 tcpstat
.tcps_sc_reset
++;
635 syncache_badack(struct in_conninfo
*inc
)
638 struct syncache_head
*sch
;
640 sc
= syncache_lookup(inc
, &sch
);
642 syncache_drop(sc
, sch
);
643 tcpstat
.tcps_sc_badack
++;
648 syncache_unreach(struct in_conninfo
*inc
, struct tcphdr
*th
)
651 struct syncache_head
*sch
;
653 /* we are called at splnet() here */
654 sc
= syncache_lookup(inc
, &sch
);
658 /* If the sequence number != sc_iss, then it's a bogus ICMP msg */
659 if (ntohl(th
->th_seq
) != sc
->sc_iss
)
663 * If we've rertransmitted 3 times and this is our second error,
664 * we remove the entry. Otherwise, we allow it to continue on.
665 * This prevents us from incorrectly nuking an entry during a
666 * spurious network outage.
670 if ((sc
->sc_flags
& SCF_UNREACH
) == 0 || sc
->sc_rxtslot
< 3) {
671 sc
->sc_flags
|= SCF_UNREACH
;
674 syncache_drop(sc
, sch
);
675 tcpstat
.tcps_sc_unreach
++;
679 * Build a new TCP socket structure from a syncache entry.
681 * This is called from the context of the SYN+ACK
683 static struct socket
*
684 syncache_socket(struct syncache
*sc
, struct socket
*lso
, struct mbuf
*m
)
686 struct inpcb
*inp
= NULL
, *linp
;
691 const boolean_t isipv6
= sc
->sc_inc
.inc_isipv6
;
693 const boolean_t isipv6
= FALSE
;
697 * Ok, create the full blown connection, and set things up
698 * as they would have been set up if we had created the
699 * connection when the SYN arrived. If we can't create
700 * the connection, abort it.
702 so
= sonewconn(lso
, SS_ISCONNECTED
);
705 * Drop the connection; we will send a RST if the peer
706 * retransmits the ACK,
708 tcpstat
.tcps_listendrop
++;
713 * Set the protocol processing port for the socket to the current
714 * port (that the connection came in on).
716 sosetport(so
, &curthread
->td_msgport
);
719 * Insert new socket into hash list.
722 inp
->inp_inc
.inc_isipv6
= sc
->sc_inc
.inc_isipv6
;
724 inp
->in6p_laddr
= sc
->sc_inc
.inc6_laddr
;
727 inp
->inp_vflag
&= ~INP_IPV6
;
728 inp
->inp_vflag
|= INP_IPV4
;
729 inp
->inp_flags
&= ~IN6P_IPV6_V6ONLY
;
731 inp
->inp_laddr
= sc
->sc_inc
.inc_laddr
;
733 inp
->inp_lport
= sc
->sc_inc
.inc_lport
;
734 if (in_pcbinsporthash(inp
) != 0) {
736 * Undo the assignments above if we failed to
737 * put the PCB on the hash lists.
740 inp
->in6p_laddr
= kin6addr_any
;
742 inp
->inp_laddr
.s_addr
= INADDR_ANY
;
748 /* copy old policy into new socket's */
749 if (ipsec_copy_policy(linp
->inp_sp
, inp
->inp_sp
))
750 kprintf("syncache_expand: could not copy policy\n");
753 struct in6_addr laddr6
;
754 struct sockaddr_in6 sin6
;
756 * Inherit socket options from the listening socket.
757 * Note that in6p_inputopts are not (and should not be)
758 * copied, since it stores previously received options and is
759 * used to detect if each new option is different than the
760 * previous one and hence should be passed to a user.
761 * If we copied in6p_inputopts, a user would not be able to
762 * receive options just after calling the accept system call.
764 inp
->inp_flags
|= linp
->inp_flags
& INP_CONTROLOPTS
;
765 if (linp
->in6p_outputopts
)
766 inp
->in6p_outputopts
=
767 ip6_copypktopts(linp
->in6p_outputopts
, M_INTWAIT
);
768 inp
->in6p_route
= sc
->sc_route6
;
769 sc
->sc_route6
.ro_rt
= NULL
;
771 sin6
.sin6_family
= AF_INET6
;
772 sin6
.sin6_len
= sizeof sin6
;
773 sin6
.sin6_addr
= sc
->sc_inc
.inc6_faddr
;
774 sin6
.sin6_port
= sc
->sc_inc
.inc_fport
;
775 sin6
.sin6_flowinfo
= sin6
.sin6_scope_id
= 0;
776 laddr6
= inp
->in6p_laddr
;
777 if (IN6_IS_ADDR_UNSPECIFIED(&inp
->in6p_laddr
))
778 inp
->in6p_laddr
= sc
->sc_inc
.inc6_laddr
;
779 if (in6_pcbconnect(inp
, (struct sockaddr
*)&sin6
, &thread0
)) {
780 inp
->in6p_laddr
= laddr6
;
784 struct in_addr laddr
;
785 struct sockaddr_in sin
;
787 inp
->inp_options
= ip_srcroute(m
);
788 if (inp
->inp_options
== NULL
) {
789 inp
->inp_options
= sc
->sc_ipopts
;
790 sc
->sc_ipopts
= NULL
;
792 inp
->inp_route
= sc
->sc_route
;
793 sc
->sc_route
.ro_rt
= NULL
;
795 sin
.sin_family
= AF_INET
;
796 sin
.sin_len
= sizeof sin
;
797 sin
.sin_addr
= sc
->sc_inc
.inc_faddr
;
798 sin
.sin_port
= sc
->sc_inc
.inc_fport
;
799 bzero(sin
.sin_zero
, sizeof sin
.sin_zero
);
800 laddr
= inp
->inp_laddr
;
801 if (inp
->inp_laddr
.s_addr
== INADDR_ANY
)
802 inp
->inp_laddr
= sc
->sc_inc
.inc_laddr
;
803 if (in_pcbconnect(inp
, (struct sockaddr
*)&sin
, &thread0
)) {
804 inp
->inp_laddr
= laddr
;
810 * The current port should be in the context of the SYN+ACK and
811 * so should match the tcp address port.
813 * XXX we may be running on the netisr thread instead of a tcp
814 * thread, in which case port will not match
815 * curthread->td_msgport.
818 port
= tcp6_addrport();
820 port
= tcp_addrport(inp
->inp_faddr
.s_addr
, inp
->inp_fport
,
821 inp
->inp_laddr
.s_addr
, inp
->inp_lport
);
823 /*KKASSERT(port == &curthread->td_msgport);*/
826 tp
->t_state
= TCPS_SYN_RECEIVED
;
827 tp
->iss
= sc
->sc_iss
;
828 tp
->irs
= sc
->sc_irs
;
831 tp
->snd_wl1
= sc
->sc_irs
;
832 tp
->rcv_up
= sc
->sc_irs
+ 1;
833 tp
->rcv_wnd
= sc
->sc_wnd
;
834 tp
->rcv_adv
+= tp
->rcv_wnd
;
836 tp
->t_flags
= sototcpcb(lso
)->t_flags
& (TF_NOPUSH
| TF_NODELAY
);
837 if (sc
->sc_flags
& SCF_NOOPT
)
838 tp
->t_flags
|= TF_NOOPT
;
839 if (sc
->sc_flags
& SCF_WINSCALE
) {
840 tp
->t_flags
|= TF_REQ_SCALE
| TF_RCVD_SCALE
;
841 tp
->requested_s_scale
= sc
->sc_requested_s_scale
;
842 tp
->request_r_scale
= sc
->sc_request_r_scale
;
844 if (sc
->sc_flags
& SCF_TIMESTAMP
) {
845 tp
->t_flags
|= TF_REQ_TSTMP
| TF_RCVD_TSTMP
;
846 tp
->ts_recent
= sc
->sc_tsrecent
;
847 tp
->ts_recent_age
= ticks
;
849 if (sc
->sc_flags
& SCF_SACK_PERMITTED
)
850 tp
->t_flags
|= TF_SACK_PERMITTED
;
853 if (sc
->sc_flags
& SCF_SIGNATURE
)
854 tp
->t_flags
|= TF_SIGNATURE
;
855 #endif /* TCP_SIGNATURE */
858 tcp_mss(tp
, sc
->sc_peer_mss
);
861 * If the SYN,ACK was retransmitted, reset cwnd to 1 segment.
863 if (sc
->sc_rxtslot
!= 0)
864 tp
->snd_cwnd
= tp
->t_maxseg
;
865 tcp_create_timermsg(tp
, port
);
866 tcp_callout_reset(tp
, tp
->tt_keep
, tcp_keepinit
, tcp_timer_keep
);
868 tcpstat
.tcps_accepts
++;
878 * This function gets called when we receive an ACK for a
879 * socket in the LISTEN state. We look up the connection
880 * in the syncache, and if its there, we pull it out of
881 * the cache and turn it into a full-blown connection in
882 * the SYN-RECEIVED state.
885 syncache_expand(struct in_conninfo
*inc
, struct tcphdr
*th
, struct socket
**sop
,
889 struct syncache_head
*sch
;
892 sc
= syncache_lookup(inc
, &sch
);
895 * There is no syncache entry, so see if this ACK is
896 * a returning syncookie. To do this, first:
897 * A. See if this socket has had a syncache entry dropped in
898 * the past. We don't want to accept a bogus syncookie
899 * if we've never received a SYN.
900 * B. check that the syncookie is valid. If it is, then
901 * cobble up a fake syncache entry, and return.
905 sc
= syncookie_lookup(inc
, th
, *sop
);
909 tcpstat
.tcps_sc_recvcookie
++;
913 * If seg contains an ACK, but not for our SYN/ACK, send a RST.
915 if (th
->th_ack
!= sc
->sc_iss
+ 1)
918 so
= syncache_socket(sc
, *sop
, m
);
922 /* XXXjlemon check this - is this correct? */
923 tcp_respond(NULL
, m
, m
, th
,
924 th
->th_seq
+ tlen
, (tcp_seq
)0, TH_RST
| TH_ACK
);
926 m_freem(m
); /* XXX only needed for above */
927 tcpstat
.tcps_sc_aborted
++;
929 tcpstat
.tcps_sc_completed
++;
934 syncache_drop(sc
, sch
);
940 * Given a LISTEN socket and an inbound SYN request, add
941 * this to the syn cache, and send back a segment:
942 * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK>
945 * IMPORTANT NOTE: We do _NOT_ ACK data that might accompany the SYN.
946 * Doing so would require that we hold onto the data and deliver it
947 * to the application. However, if we are the target of a SYN-flood
948 * DoS attack, an attacker could send data which would eventually
949 * consume all available buffer space if it were ACKed. By not ACKing
950 * the data, we avoid this DoS scenario.
953 syncache_add(struct in_conninfo
*inc
, struct tcpopt
*to
, struct tcphdr
*th
,
954 struct socket
**sop
, struct mbuf
*m
)
956 struct tcp_syncache_percpu
*syncache_percpu
;
959 struct syncache
*sc
= NULL
;
960 struct syncache_head
*sch
;
961 struct mbuf
*ipopts
= NULL
;
964 syncache_percpu
= &tcp_syncache_percpu
[mycpu
->gd_cpuid
];
969 * Remember the IP options, if any.
972 if (!inc
->inc_isipv6
)
974 ipopts
= ip_srcroute(m
);
977 * See if we already have an entry for this connection.
978 * If we do, resend the SYN,ACK, and reset the retransmit timer.
981 * The syncache should be re-initialized with the contents
982 * of the new SYN which may have different options.
984 sc
= syncache_lookup(inc
, &sch
);
986 tcpstat
.tcps_sc_dupsyn
++;
989 * If we were remembering a previous source route,
990 * forget it and use the new one we've been given.
993 m_free(sc
->sc_ipopts
);
994 sc
->sc_ipopts
= ipopts
;
997 * Update timestamp if present.
999 if (sc
->sc_flags
& SCF_TIMESTAMP
)
1000 sc
->sc_tsrecent
= to
->to_tsval
;
1002 /* Just update the TOF_SACK_PERMITTED for now. */
1003 if (tcp_do_sack
&& (to
->to_flags
& TOF_SACK_PERMITTED
))
1004 sc
->sc_flags
|= SCF_SACK_PERMITTED
;
1006 sc
->sc_flags
&= ~SCF_SACK_PERMITTED
;
1009 * PCB may have changed, pick up new values.
1012 sc
->sc_tp
->t_flags
&= ~TF_SYNCACHE
;
1013 tp
->t_flags
|= TF_SYNCACHE
;
1016 sc
->sc_inp_gencnt
= tp
->t_inpcb
->inp_gencnt
;
1017 if (syncache_respond(sc
, m
) == 0) {
1018 TAILQ_REMOVE(&syncache_percpu
->timerq
[sc
->sc_rxtslot
],
1020 syncache_timeout(syncache_percpu
, sc
, sc
->sc_rxtslot
);
1021 tcpstat
.tcps_sndacks
++;
1022 tcpstat
.tcps_sndtotal
++;
1029 * Fill in the syncache values.
1031 sc
= kmalloc(sizeof(struct syncache
), M_SYNCACHE
, M_WAITOK
|M_ZERO
);
1032 sc
->sc_inp_gencnt
= tp
->t_inpcb
->inp_gencnt
;
1033 sc
->sc_ipopts
= ipopts
;
1034 sc
->sc_inc
.inc_fport
= inc
->inc_fport
;
1035 sc
->sc_inc
.inc_lport
= inc
->inc_lport
;
1037 tp
->t_flags
|= TF_SYNCACHE
;
1039 sc
->sc_inc
.inc_isipv6
= inc
->inc_isipv6
;
1040 if (inc
->inc_isipv6
) {
1041 sc
->sc_inc
.inc6_faddr
= inc
->inc6_faddr
;
1042 sc
->sc_inc
.inc6_laddr
= inc
->inc6_laddr
;
1043 sc
->sc_route6
.ro_rt
= NULL
;
1047 sc
->sc_inc
.inc_faddr
= inc
->inc_faddr
;
1048 sc
->sc_inc
.inc_laddr
= inc
->inc_laddr
;
1049 sc
->sc_route
.ro_rt
= NULL
;
1051 sc
->sc_irs
= th
->th_seq
;
1053 sc
->sc_peer_mss
= to
->to_flags
& TOF_MSS
? to
->to_mss
: 0;
1055 sc
->sc_iss
= syncookie_generate(sc
);
1057 sc
->sc_iss
= karc4random();
1059 /* Initial receive window: clip ssb_space to [0 .. TCP_MAXWIN] */
1060 win
= ssb_space(&so
->so_rcv
);
1062 win
= imin(win
, TCP_MAXWIN
);
1065 if (tcp_do_rfc1323
) {
1067 * A timestamp received in a SYN makes
1068 * it ok to send timestamp requests and replies.
1070 if (to
->to_flags
& TOF_TS
) {
1071 sc
->sc_tsrecent
= to
->to_tsval
;
1072 sc
->sc_flags
|= SCF_TIMESTAMP
;
1074 if (to
->to_flags
& TOF_SCALE
) {
1075 int wscale
= TCP_MIN_WINSHIFT
;
1077 /* Compute proper scaling value from buffer space */
1078 while (wscale
< TCP_MAX_WINSHIFT
&&
1079 (TCP_MAXWIN
<< wscale
) < so
->so_rcv
.ssb_hiwat
) {
1082 sc
->sc_request_r_scale
= wscale
;
1083 sc
->sc_requested_s_scale
= to
->to_requested_s_scale
;
1084 sc
->sc_flags
|= SCF_WINSCALE
;
1087 if (tcp_do_sack
&& (to
->to_flags
& TOF_SACK_PERMITTED
))
1088 sc
->sc_flags
|= SCF_SACK_PERMITTED
;
1089 if (tp
->t_flags
& TF_NOOPT
)
1090 sc
->sc_flags
= SCF_NOOPT
;
1091 #ifdef TCP_SIGNATURE
1093 * If listening socket requested TCP digests, and received SYN
1094 * contains the option, flag this in the syncache so that
1095 * syncache_respond() will do the right thing with the SYN+ACK.
1096 * XXX Currently we always record the option by default and will
1097 * attempt to use it in syncache_respond().
1099 if (to
->to_flags
& TOF_SIGNATURE
)
1100 sc
->sc_flags
= SCF_SIGNATURE
;
1101 #endif /* TCP_SIGNATURE */
1103 if (syncache_respond(sc
, m
) == 0) {
1104 syncache_insert(sc
, sch
);
1105 tcpstat
.tcps_sndacks
++;
1106 tcpstat
.tcps_sndtotal
++;
1109 tcpstat
.tcps_sc_dropped
++;
1116 syncache_respond(struct syncache
*sc
, struct mbuf
*m
)
1120 u_int16_t tlen
, hlen
, mssopt
;
1121 struct ip
*ip
= NULL
;
1124 struct ip6_hdr
*ip6
= NULL
;
1126 const boolean_t isipv6
= sc
->sc_inc
.inc_isipv6
;
1128 const boolean_t isipv6
= FALSE
;
1132 rt
= tcp_rtlookup6(&sc
->sc_inc
);
1134 mssopt
= rt
->rt_ifp
->if_mtu
-
1135 (sizeof(struct ip6_hdr
) + sizeof(struct tcphdr
));
1137 mssopt
= tcp_v6mssdflt
;
1138 hlen
= sizeof(struct ip6_hdr
);
1140 rt
= tcp_rtlookup(&sc
->sc_inc
);
1142 mssopt
= rt
->rt_ifp
->if_mtu
-
1143 (sizeof(struct ip
) + sizeof(struct tcphdr
));
1145 mssopt
= tcp_mssdflt
;
1146 hlen
= sizeof(struct ip
);
1149 /* Compute the size of the TCP options. */
1150 if (sc
->sc_flags
& SCF_NOOPT
) {
1153 optlen
= TCPOLEN_MAXSEG
+
1154 ((sc
->sc_flags
& SCF_WINSCALE
) ? 4 : 0) +
1155 ((sc
->sc_flags
& SCF_TIMESTAMP
) ? TCPOLEN_TSTAMP_APPA
: 0) +
1156 ((sc
->sc_flags
& SCF_SACK_PERMITTED
) ?
1157 TCPOLEN_SACK_PERMITTED_ALIGNED
: 0);
1158 #ifdef TCP_SIGNATURE
1159 optlen
+= ((sc
->sc_flags
& SCF_SIGNATURE
) ?
1160 (TCPOLEN_SIGNATURE
+ 2) : 0);
1161 #endif /* TCP_SIGNATURE */
1163 tlen
= hlen
+ sizeof(struct tcphdr
) + optlen
;
1167 * assume that the entire packet will fit in a header mbuf
1169 KASSERT(max_linkhdr
+ tlen
<= MHLEN
, ("syncache: mbuf too small"));
1172 * XXX shouldn't this reuse the mbuf if possible ?
1173 * Create the IP+TCP header from scratch.
1178 m
= m_gethdr(MB_DONTWAIT
, MT_HEADER
);
1181 m
->m_data
+= max_linkhdr
;
1183 m
->m_pkthdr
.len
= tlen
;
1184 m
->m_pkthdr
.rcvif
= NULL
;
1187 ip6
= mtod(m
, struct ip6_hdr
*);
1188 ip6
->ip6_vfc
= IPV6_VERSION
;
1189 ip6
->ip6_nxt
= IPPROTO_TCP
;
1190 ip6
->ip6_src
= sc
->sc_inc
.inc6_laddr
;
1191 ip6
->ip6_dst
= sc
->sc_inc
.inc6_faddr
;
1192 ip6
->ip6_plen
= htons(tlen
- hlen
);
1193 /* ip6_hlim is set after checksum */
1194 /* ip6_flow = ??? */
1196 th
= (struct tcphdr
*)(ip6
+ 1);
1198 ip
= mtod(m
, struct ip
*);
1199 ip
->ip_v
= IPVERSION
;
1200 ip
->ip_hl
= sizeof(struct ip
) >> 2;
1205 ip
->ip_p
= IPPROTO_TCP
;
1206 ip
->ip_src
= sc
->sc_inc
.inc_laddr
;
1207 ip
->ip_dst
= sc
->sc_inc
.inc_faddr
;
1208 ip
->ip_ttl
= sc
->sc_tp
->t_inpcb
->inp_ip_ttl
; /* XXX */
1209 ip
->ip_tos
= sc
->sc_tp
->t_inpcb
->inp_ip_tos
; /* XXX */
1212 * See if we should do MTU discovery. Route lookups are
1213 * expensive, so we will only unset the DF bit if:
1215 * 1) path_mtu_discovery is disabled
1216 * 2) the SCF_UNREACH flag has been set
1218 if (path_mtu_discovery
1219 && ((sc
->sc_flags
& SCF_UNREACH
) == 0)) {
1220 ip
->ip_off
|= IP_DF
;
1223 th
= (struct tcphdr
*)(ip
+ 1);
1225 th
->th_sport
= sc
->sc_inc
.inc_lport
;
1226 th
->th_dport
= sc
->sc_inc
.inc_fport
;
1228 th
->th_seq
= htonl(sc
->sc_iss
);
1229 th
->th_ack
= htonl(sc
->sc_irs
+ 1);
1230 th
->th_off
= (sizeof(struct tcphdr
) + optlen
) >> 2;
1232 th
->th_flags
= TH_SYN
| TH_ACK
;
1233 th
->th_win
= htons(sc
->sc_wnd
);
1236 /* Tack on the TCP options. */
1239 optp
= (u_int8_t
*)(th
+ 1);
1240 *optp
++ = TCPOPT_MAXSEG
;
1241 *optp
++ = TCPOLEN_MAXSEG
;
1242 *optp
++ = (mssopt
>> 8) & 0xff;
1243 *optp
++ = mssopt
& 0xff;
1245 if (sc
->sc_flags
& SCF_WINSCALE
) {
1246 *((u_int32_t
*)optp
) = htonl(TCPOPT_NOP
<< 24 |
1247 TCPOPT_WINDOW
<< 16 | TCPOLEN_WINDOW
<< 8 |
1248 sc
->sc_request_r_scale
);
1252 if (sc
->sc_flags
& SCF_TIMESTAMP
) {
1253 u_int32_t
*lp
= (u_int32_t
*)(optp
);
1255 /* Form timestamp option as shown in appendix A of RFC 1323. */
1256 *lp
++ = htonl(TCPOPT_TSTAMP_HDR
);
1257 *lp
++ = htonl(ticks
);
1258 *lp
= htonl(sc
->sc_tsrecent
);
1259 optp
+= TCPOLEN_TSTAMP_APPA
;
1262 #ifdef TCP_SIGNATURE
1264 * Handle TCP-MD5 passive opener response.
1266 if (sc
->sc_flags
& SCF_SIGNATURE
) {
1267 u_int8_t
*bp
= optp
;
1270 *bp
++ = TCPOPT_SIGNATURE
;
1271 *bp
++ = TCPOLEN_SIGNATURE
;
1272 for (i
= 0; i
< TCP_SIGLEN
; i
++)
1274 tcpsignature_compute(m
, 0, optlen
,
1275 optp
+ 2, IPSEC_DIR_OUTBOUND
);
1278 optp
+= TCPOLEN_SIGNATURE
+ 2;
1280 #endif /* TCP_SIGNATURE */
1282 if (sc
->sc_flags
& SCF_SACK_PERMITTED
) {
1283 *((u_int32_t
*)optp
) = htonl(TCPOPT_SACK_PERMITTED_ALIGNED
);
1284 optp
+= TCPOLEN_SACK_PERMITTED_ALIGNED
;
1289 struct route_in6
*ro6
= &sc
->sc_route6
;
1292 th
->th_sum
= in6_cksum(m
, IPPROTO_TCP
, hlen
, tlen
- hlen
);
1293 ip6
->ip6_hlim
= in6_selecthlim(NULL
,
1294 ro6
->ro_rt
? ro6
->ro_rt
->rt_ifp
: NULL
);
1295 error
= ip6_output(m
, NULL
, ro6
, 0, NULL
, NULL
,
1296 sc
->sc_tp
->t_inpcb
);
1298 th
->th_sum
= in_pseudo(ip
->ip_src
.s_addr
, ip
->ip_dst
.s_addr
,
1299 htons(tlen
- hlen
+ IPPROTO_TCP
));
1300 m
->m_pkthdr
.csum_flags
= CSUM_TCP
;
1301 m
->m_pkthdr
.csum_data
= offsetof(struct tcphdr
, th_sum
);
1302 error
= ip_output(m
, sc
->sc_ipopts
, &sc
->sc_route
,
1303 IP_DEBUGROUTE
, NULL
, sc
->sc_tp
->t_inpcb
);
1311 * |. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .|
1313 * | MD5(laddr,faddr,secret,lport,fport) |. . . . . . .|
1315 * (A): peer mss index
1319 * The values below are chosen to minimize the size of the tcp_secret
1320 * table, as well as providing roughly a 16 second lifetime for the cookie.
1323 #define SYNCOOKIE_WNDBITS 5 /* exposed bits for window indexing */
1324 #define SYNCOOKIE_TIMESHIFT 1 /* scale ticks to window time units */
1326 #define SYNCOOKIE_WNDMASK ((1 << SYNCOOKIE_WNDBITS) - 1)
1327 #define SYNCOOKIE_NSECRETS (1 << SYNCOOKIE_WNDBITS)
1328 #define SYNCOOKIE_TIMEOUT \
1329 (hz * (1 << SYNCOOKIE_WNDBITS) / (1 << SYNCOOKIE_TIMESHIFT))
1330 #define SYNCOOKIE_DATAMASK ((3 << SYNCOOKIE_WNDBITS) | SYNCOOKIE_WNDMASK)
1333 u_int32_t ts_secbits
[4];
1335 } tcp_secret
[SYNCOOKIE_NSECRETS
];
1337 static int tcp_msstab
[] = { 0, 536, 1460, 8960 };
1339 static MD5_CTX syn_ctx
;
1341 #define MD5Add(v) MD5Update(&syn_ctx, (u_char *)&v, sizeof(v))
1344 u_int32_t laddr
, faddr
;
1345 u_int32_t secbits
[4];
1346 u_int16_t lport
, fport
;
1350 CTASSERT(sizeof(struct md5_add
) == 28);
1354 * Consider the problem of a recreated (and retransmitted) cookie. If the
1355 * original SYN was accepted, the connection is established. The second
1356 * SYN is inflight, and if it arrives with an ISN that falls within the
1357 * receive window, the connection is killed.
1359 * However, since cookies have other problems, this may not be worth
1364 syncookie_generate(struct syncache
*sc
)
1366 u_int32_t md5_buffer
[4];
1371 const boolean_t isipv6
= sc
->sc_inc
.inc_isipv6
;
1373 const boolean_t isipv6
= FALSE
;
1376 idx
= ((ticks
<< SYNCOOKIE_TIMESHIFT
) / hz
) & SYNCOOKIE_WNDMASK
;
1377 if (tcp_secret
[idx
].ts_expire
< ticks
) {
1378 for (i
= 0; i
< 4; i
++)
1379 tcp_secret
[idx
].ts_secbits
[i
] = karc4random();
1380 tcp_secret
[idx
].ts_expire
= ticks
+ SYNCOOKIE_TIMEOUT
;
1382 for (data
= sizeof(tcp_msstab
) / sizeof(int) - 1; data
> 0; data
--)
1383 if (tcp_msstab
[data
] <= sc
->sc_peer_mss
)
1385 data
= (data
<< SYNCOOKIE_WNDBITS
) | idx
;
1386 data
^= sc
->sc_irs
; /* peer's iss */
1389 MD5Add(sc
->sc_inc
.inc6_laddr
);
1390 MD5Add(sc
->sc_inc
.inc6_faddr
);
1394 add
.laddr
= sc
->sc_inc
.inc_laddr
.s_addr
;
1395 add
.faddr
= sc
->sc_inc
.inc_faddr
.s_addr
;
1397 add
.lport
= sc
->sc_inc
.inc_lport
;
1398 add
.fport
= sc
->sc_inc
.inc_fport
;
1399 add
.secbits
[0] = tcp_secret
[idx
].ts_secbits
[0];
1400 add
.secbits
[1] = tcp_secret
[idx
].ts_secbits
[1];
1401 add
.secbits
[2] = tcp_secret
[idx
].ts_secbits
[2];
1402 add
.secbits
[3] = tcp_secret
[idx
].ts_secbits
[3];
1404 MD5Final((u_char
*)&md5_buffer
, &syn_ctx
);
1405 data
^= (md5_buffer
[0] & ~SYNCOOKIE_WNDMASK
);
1409 static struct syncache
*
1410 syncookie_lookup(struct in_conninfo
*inc
, struct tcphdr
*th
, struct socket
*so
)
1412 u_int32_t md5_buffer
[4];
1413 struct syncache
*sc
;
1418 data
= (th
->th_ack
- 1) ^ (th
->th_seq
- 1); /* remove ISS */
1419 idx
= data
& SYNCOOKIE_WNDMASK
;
1420 if (tcp_secret
[idx
].ts_expire
< ticks
||
1421 sototcpcb(so
)->ts_recent
+ SYNCOOKIE_TIMEOUT
< ticks
)
1425 if (inc
->inc_isipv6
) {
1426 MD5Add(inc
->inc6_laddr
);
1427 MD5Add(inc
->inc6_faddr
);
1433 add
.laddr
= inc
->inc_laddr
.s_addr
;
1434 add
.faddr
= inc
->inc_faddr
.s_addr
;
1436 add
.lport
= inc
->inc_lport
;
1437 add
.fport
= inc
->inc_fport
;
1438 add
.secbits
[0] = tcp_secret
[idx
].ts_secbits
[0];
1439 add
.secbits
[1] = tcp_secret
[idx
].ts_secbits
[1];
1440 add
.secbits
[2] = tcp_secret
[idx
].ts_secbits
[2];
1441 add
.secbits
[3] = tcp_secret
[idx
].ts_secbits
[3];
1443 MD5Final((u_char
*)&md5_buffer
, &syn_ctx
);
1444 data
^= md5_buffer
[0];
1445 if (data
& ~SYNCOOKIE_DATAMASK
)
1447 data
= data
>> SYNCOOKIE_WNDBITS
;
1450 * Fill in the syncache values.
1451 * XXX duplicate code from syncache_add
1453 sc
= kmalloc(sizeof(struct syncache
), M_SYNCACHE
, M_WAITOK
|M_ZERO
);
1454 sc
->sc_ipopts
= NULL
;
1455 sc
->sc_inc
.inc_fport
= inc
->inc_fport
;
1456 sc
->sc_inc
.inc_lport
= inc
->inc_lport
;
1458 sc
->sc_inc
.inc_isipv6
= inc
->inc_isipv6
;
1459 if (inc
->inc_isipv6
) {
1460 sc
->sc_inc
.inc6_faddr
= inc
->inc6_faddr
;
1461 sc
->sc_inc
.inc6_laddr
= inc
->inc6_laddr
;
1462 sc
->sc_route6
.ro_rt
= NULL
;
1466 sc
->sc_inc
.inc_faddr
= inc
->inc_faddr
;
1467 sc
->sc_inc
.inc_laddr
= inc
->inc_laddr
;
1468 sc
->sc_route
.ro_rt
= NULL
;
1470 sc
->sc_irs
= th
->th_seq
- 1;
1471 sc
->sc_iss
= th
->th_ack
- 1;
1472 wnd
= ssb_space(&so
->so_rcv
);
1474 wnd
= imin(wnd
, TCP_MAXWIN
);
1478 sc
->sc_peer_mss
= tcp_msstab
[data
];