xref: /freebsd/crypto/openssh/mac.c (revision 1e413cf93298b5b97441a21d9a50fdcd0ee9945e)
1 /* $OpenBSD: mac.c,v 1.12 2006/08/03 03:34:42 deraadt Exp $ */
2 /*
3  * Copyright (c) 2001 Markus Friedl.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24  */
25 
26 #include "includes.h"
27 
28 #include <sys/types.h>
29 
30 #include <openssl/hmac.h>
31 
32 #include <stdarg.h>
33 #include <string.h>
34 #include <signal.h>
35 
36 #include "xmalloc.h"
37 #include "log.h"
38 #include "cipher.h"
39 #include "buffer.h"
40 #include "key.h"
41 #include "kex.h"
42 #include "mac.h"
43 #include "misc.h"
44 
45 struct {
46 	char		*name;
47 	const EVP_MD *	(*mdfunc)(void);
48 	int		truncatebits;	/* truncate digest if != 0 */
49 } macs[] = {
50 	{ "hmac-sha1",			EVP_sha1, 0, },
51 	{ "hmac-sha1-96",		EVP_sha1, 96 },
52 	{ "hmac-md5",			EVP_md5, 0 },
53 	{ "hmac-md5-96",		EVP_md5, 96 },
54 	{ "hmac-ripemd160",		EVP_ripemd160, 0 },
55 	{ "hmac-ripemd160@openssh.com",	EVP_ripemd160, 0 },
56 	{ NULL,				NULL, 0 }
57 };
58 
59 int
60 mac_init(Mac *mac, char *name)
61 {
62 	int i, evp_len;
63 
64 	for (i = 0; macs[i].name; i++) {
65 		if (strcmp(name, macs[i].name) == 0) {
66 			if (mac != NULL) {
67 				mac->md = (*macs[i].mdfunc)();
68 				if ((evp_len = EVP_MD_size(mac->md)) <= 0)
69 					fatal("mac %s len %d", name, evp_len);
70 				mac->key_len = mac->mac_len = (u_int)evp_len;
71 				if (macs[i].truncatebits != 0)
72 					mac->mac_len = macs[i].truncatebits/8;
73 			}
74 			debug2("mac_init: found %s", name);
75 			return (0);
76 		}
77 	}
78 	debug2("mac_init: unknown %s", name);
79 	return (-1);
80 }
81 
82 u_char *
83 mac_compute(Mac *mac, u_int32_t seqno, u_char *data, int datalen)
84 {
85 	HMAC_CTX c;
86 	static u_char m[EVP_MAX_MD_SIZE];
87 	u_char b[4];
88 
89 	if (mac->key == NULL)
90 		fatal("mac_compute: no key");
91 	if (mac->mac_len > sizeof(m))
92 		fatal("mac_compute: mac too long");
93 	HMAC_Init(&c, mac->key, mac->key_len, mac->md);
94 	put_u32(b, seqno);
95 	HMAC_Update(&c, b, sizeof(b));
96 	HMAC_Update(&c, data, datalen);
97 	HMAC_Final(&c, m, NULL);
98 	HMAC_cleanup(&c);
99 	return (m);
100 }
101 
102 /* XXX copied from ciphers_valid */
103 #define	MAC_SEP	","
104 int
105 mac_valid(const char *names)
106 {
107 	char *maclist, *cp, *p;
108 
109 	if (names == NULL || strcmp(names, "") == 0)
110 		return (0);
111 	maclist = cp = xstrdup(names);
112 	for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0';
113 	    (p = strsep(&cp, MAC_SEP))) {
114 		if (mac_init(NULL, p) < 0) {
115 			debug("bad mac %s [%s]", p, names);
116 			xfree(maclist);
117 			return (0);
118 		} else {
119 			debug3("mac ok: %s [%s]", p, names);
120 		}
121 	}
122 	debug3("macs ok: [%s]", names);
123 	xfree(maclist);
124 	return (1);
125 }
126