mac.c revision 98675 
1/*
2 * Copyright (c) 2001 Markus Friedl.  All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
14 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
15 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
16 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
17 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
18 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
19 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
20 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
22 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
23 */
24
25#include "includes.h"
26RCSID("$OpenBSD: mac.c,v 1.5 2002/05/16 22:02:50 markus Exp $");
27
28#include <openssl/hmac.h>
29
30#include "xmalloc.h"
31#include "getput.h"
32#include "log.h"
33#include "cipher.h"
34#include "kex.h"
35#include "mac.h"
36
37struct {
38	char		*name;
39	const EVP_MD *	(*mdfunc)(void);
40	int		truncatebits;	/* truncate digest if != 0 */
41} macs[] = {
42	{ "hmac-sha1",			EVP_sha1, 0, },
43	{ "hmac-sha1-96",		EVP_sha1, 96 },
44	{ "hmac-md5",			EVP_md5, 0 },
45	{ "hmac-md5-96",		EVP_md5, 96 },
46	{ "hmac-ripemd160",		EVP_ripemd160, 0 },
47	{ "hmac-ripemd160@openssh.com",	EVP_ripemd160, 0 },
48	{ NULL,				NULL, 0 }
49};
50
51int
52mac_init(Mac *mac, char *name)
53{
54	int i;
55	for (i = 0; macs[i].name; i++) {
56		if (strcmp(name, macs[i].name) == 0) {
57			if (mac != NULL) {
58				mac->md = (*macs[i].mdfunc)();
59				mac->key_len = mac->mac_len = EVP_MD_size(mac->md);
60				if (macs[i].truncatebits != 0)
61					mac->mac_len = macs[i].truncatebits/8;
62			}
63			debug2("mac_init: found %s", name);
64			return (0);
65		}
66	}
67	debug2("mac_init: unknown %s", name);
68	return (-1);
69}
70
71u_char *
72mac_compute(Mac *mac, u_int32_t seqno, u_char *data, int datalen)
73{
74	HMAC_CTX c;
75	static u_char m[EVP_MAX_MD_SIZE];
76	u_char b[4];
77
78	if (mac->key == NULL)
79		fatal("mac_compute: no key");
80	if (mac->mac_len > sizeof(m))
81		fatal("mac_compute: mac too long");
82	HMAC_Init(&c, mac->key, mac->key_len, mac->md);
83	PUT_32BIT(b, seqno);
84	HMAC_Update(&c, b, sizeof(b));
85	HMAC_Update(&c, data, datalen);
86	HMAC_Final(&c, m, NULL);
87	HMAC_cleanup(&c);
88	return (m);
89}
90
91/* XXX copied from ciphers_valid */
92#define	MAC_SEP	","
93int
94mac_valid(const char *names)
95{
96	char *maclist, *cp, *p;
97
98	if (names == NULL || strcmp(names, "") == 0)
99		return (0);
100	maclist = cp = xstrdup(names);
101	for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0';
102	    (p = strsep(&cp, MAC_SEP))) {
103		if (mac_init(NULL, p) < 0) {
104			debug("bad mac %s [%s]", p, names);
105			xfree(maclist);
106			return (0);
107		} else {
108			debug3("mac ok: %s [%s]", p, names);
109		}
110	}
111	debug3("macs ok: [%s]", names);
112	xfree(maclist);
113	return (1);
114}
115