1/*	$OpenBSD: radius_msgauth.c,v 1.5 2024/08/14 04:50:31 yasuoka Exp $ */
2
3/*-
4 * Copyright (c) 2009 Internet Initiative Japan Inc.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE"AUTHOR" AND CONTRIBUTORS AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29#include <sys/types.h>
30#include <sys/socket.h>
31#include <netinet/in.h>
32
33#include <stdbool.h>
34#include <stdio.h>
35#include <stdlib.h>
36#include <string.h>
37
38#include <openssl/hmac.h>
39
40#include "radius.h"
41
42#include "radius_local.h"
43
44static int
45radius_calc_message_authenticator(RADIUS_PACKET * packet, const char *secret,
46    void *ma)
47{
48	const RADIUS_ATTRIBUTE	*attr;
49	const RADIUS_ATTRIBUTE	*end;
50	u_char			 zero16[16];
51	HMAC_CTX		*ctx;
52	int			 mdlen;
53	int			 ret = -1;
54
55	memset(zero16, 0, sizeof(zero16));
56
57	if ((ctx = HMAC_CTX_new()) == NULL)
58		goto err;
59
60	if (!HMAC_Init_ex(ctx, secret, strlen(secret), EVP_md5(), NULL))
61		goto err;
62
63	/*
64	 * Traverse the radius packet.
65	 */
66	if (packet->request != NULL) {
67		if (!HMAC_Update(ctx, (const u_char *)packet->pdata, 4))
68			goto err;
69		if (!HMAC_Update(ctx, (unsigned char *)packet->request->pdata
70		    ->authenticator, 16))
71			goto err;
72	} else {
73		if (!HMAC_Update(ctx, (const u_char *)packet->pdata,
74		    sizeof(RADIUS_PACKET_DATA)))
75			goto err;
76	}
77
78	attr = ATTRS_BEGIN(packet->pdata);
79	end = ATTRS_END(packet->pdata);
80
81	for (; attr < end; ATTRS_ADVANCE(attr)) {
82		if (attr->type == RADIUS_TYPE_MESSAGE_AUTHENTICATOR) {
83			if (!HMAC_Update(ctx, (u_char *)attr, 2))
84				goto err;
85			if (!HMAC_Update(ctx, (u_char *)zero16, sizeof(zero16)))
86				goto err;
87		} else {
88			if (!HMAC_Update(ctx, (u_char *)attr,
89			    (int)attr->length))
90				goto err;
91		}
92	}
93
94	if (!HMAC_Final(ctx, (u_char *)ma, &mdlen))
95		goto err;
96
97	ret = 0;
98
99 err:
100	HMAC_CTX_free(ctx);
101
102	return (ret);
103}
104
105int
106radius_put_message_authenticator(RADIUS_PACKET * packet, const char *secret)
107{
108	u_char	 ma[16];
109
110	/*
111	 * It is not required to initialize ma
112	 * because content of Message-Authenticator attribute is assumed zero
113	 * during calculation.
114	 */
115	if (radius_unshift_raw_attr(packet, RADIUS_TYPE_MESSAGE_AUTHENTICATOR,
116	    ma, sizeof(ma)) != 0)
117		return (-1);
118
119	return (radius_set_message_authenticator(packet, secret));
120}
121
122int
123radius_set_message_authenticator(RADIUS_PACKET * packet, const char *secret)
124{
125	u_char	 ma[16];
126
127	if (radius_calc_message_authenticator(packet, secret, ma) != 0)
128		return (-1);
129
130	return (radius_set_raw_attr(packet, RADIUS_TYPE_MESSAGE_AUTHENTICATOR,
131	    ma, sizeof(ma)));
132}
133
134int
135radius_check_message_authenticator(RADIUS_PACKET * packet, const char *secret)
136{
137	int	 rval;
138	size_t	 len;
139	u_char	 ma0[16], ma1[16];
140
141	if (radius_calc_message_authenticator(packet, secret, ma0) != 0)
142		return (-1);
143
144	len = sizeof(ma1);
145	if ((rval = radius_get_raw_attr(packet,
146		    RADIUS_TYPE_MESSAGE_AUTHENTICATOR, ma1, &len)) != 0)
147		return (rval);
148
149	if (len != sizeof(ma1))
150		return (-1);
151
152	return (timingsafe_bcmp(ma0, ma1, sizeof(ma1)));
153}
154