1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
|
/* $OpenBSD: cookie.c,v 1.3 1998/11/17 11:10:08 niklas Exp $ */
/* $EOM: cookie.c,v 1.17 1998/08/05 09:21:42 niklas Exp $ */
/*
* Copyright (c) 1998 Niklas Hallqvist. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by Ericsson Radio Systems.
* 4. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* This code was written under funding by Ericsson Radio Systems.
*/
#include <sys/types.h>
#include <sys/socket.h>
#include <sha1.h>
#include <stdlib.h>
#include <string.h>
#include "cookie.h"
#include "exchange.h"
#include "hash.h"
#include "log.h"
#include "timer.h"
#include "transport.h"
#include "util.h"
#define COOKIE_EVENT_FREQ 360
#define COOKIE_SECRET_SIZE 16
void cookie_secret_reset (void);
u_int8_t cookie_secret[COOKIE_SECRET_SIZE];
/*
* Generate an anti-clogging token (a protection against an attacker forcing
* us to keep state for a flood of connection requests) a.k.a. a cookie
* at BUF, LEN bytes long. The cookie will be generated by hashing of
* information found, among otherplaces, in transport T and exchange
* EXCHANGE.
*/
void
cookie_gen (struct transport *t, struct exchange *exchange, u_int8_t *buf,
size_t len)
{
struct hash* hash = hash_get (HASH_SHA1);
struct sockaddr *name;
int name_len;
hash->Init (hash->ctx);
(*t->vtbl->get_dst) (t, &name, &name_len);
hash->Update (hash->ctx, (u_int8_t *)name, name_len);
(*t->vtbl->get_src) (t, &name, &name_len);
hash->Update (hash->ctx, (u_int8_t *)name, name_len);
if (exchange->initiator)
{
u_int8_t tmpsecret[COOKIE_SECRET_SIZE];
getrandom (tmpsecret, COOKIE_SECRET_SIZE);
hash->Update (hash->ctx, tmpsecret, COOKIE_SECRET_SIZE);
}
else
{
hash->Update (hash->ctx, exchange->cookies + ISAKMP_HDR_ICOOKIE_OFF,
ISAKMP_HDR_ICOOKIE_LEN);
hash->Update (hash->ctx, cookie_secret, COOKIE_SECRET_SIZE);
}
hash->Final (hash->digest, hash->ctx);
memcpy (buf, hash->digest, len);
}
/*
* Reset the secret which is used for the responder cookie.
* As responder we do not want to keep state in the cookie
* exchange, which means when the cookie secret is reset,
* our cookie response has timed out.
*/
void
cookie_secret_reset (void)
{
getrandom (cookie_secret, COOKIE_SECRET_SIZE);
}
/*
* Handle the cookie reset event, and reschedule with timer.
*/
void
cookie_reset_event (void *arg)
{
struct timeval now;
cookie_secret_reset ();
gettimeofday (&now, 0);
now.tv_sec += COOKIE_EVENT_FREQ;
timer_add_event ("cookie_reset_event", cookie_reset_event, arg, &now);
}
void
cookie_init (void)
{
/* Start responder cookie resets. */
cookie_reset_event (NULL);
}
|
