- djm@cvs.openbsd.org 2010/01/13 04:10:50
[openssh-git.git] / mac.c
blobfabc3ed661da8d532eaeaecbc57f4da67b8c06be
1 /* $OpenBSD: mac.c,v 1.15 2008/06/13 00:51:47 dtucker Exp $ */
2 /*
3 * Copyright (c) 2001 Markus Friedl. All rights reserved.
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.
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.
26 #include "includes.h"
28 #include <sys/types.h>
30 #include <openssl/hmac.h>
32 #include <stdarg.h>
33 #include <string.h>
34 #include <signal.h>
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"
45 #include "umac.h"
47 #define SSH_EVP 1 /* OpenSSL EVP-based MAC */
48 #define SSH_UMAC 2 /* UMAC (not integrated with OpenSSL) */
50 struct {
51 char *name;
52 int type;
53 const EVP_MD * (*mdfunc)(void);
54 int truncatebits; /* truncate digest if != 0 */
55 int key_len; /* just for UMAC */
56 int len; /* just for UMAC */
57 } macs[] = {
58 { "hmac-sha1", SSH_EVP, EVP_sha1, 0, -1, -1 },
59 { "hmac-sha1-96", SSH_EVP, EVP_sha1, 96, -1, -1 },
60 { "hmac-md5", SSH_EVP, EVP_md5, 0, -1, -1 },
61 { "hmac-md5-96", SSH_EVP, EVP_md5, 96, -1, -1 },
62 { "hmac-ripemd160", SSH_EVP, EVP_ripemd160, 0, -1, -1 },
63 { "hmac-ripemd160@openssh.com", SSH_EVP, EVP_ripemd160, 0, -1, -1 },
64 { "umac-64@openssh.com", SSH_UMAC, NULL, 0, 128, 64 },
65 { NULL, 0, NULL, 0, -1, -1 }
68 static void
69 mac_setup_by_id(Mac *mac, int which)
71 int evp_len;
72 mac->type = macs[which].type;
73 if (mac->type == SSH_EVP) {
74 mac->evp_md = (*macs[which].mdfunc)();
75 if ((evp_len = EVP_MD_size(mac->evp_md)) <= 0)
76 fatal("mac %s len %d", mac->name, evp_len);
77 mac->key_len = mac->mac_len = (u_int)evp_len;
78 } else {
79 mac->mac_len = macs[which].len / 8;
80 mac->key_len = macs[which].key_len / 8;
81 mac->umac_ctx = NULL;
83 if (macs[which].truncatebits != 0)
84 mac->mac_len = macs[which].truncatebits / 8;
87 int
88 mac_setup(Mac *mac, char *name)
90 int i;
92 for (i = 0; macs[i].name; i++) {
93 if (strcmp(name, macs[i].name) == 0) {
94 if (mac != NULL)
95 mac_setup_by_id(mac, i);
96 debug2("mac_setup: found %s", name);
97 return (0);
100 debug2("mac_setup: unknown %s", name);
101 return (-1);
105 mac_init(Mac *mac)
107 if (mac->key == NULL)
108 fatal("mac_init: no key");
109 switch (mac->type) {
110 case SSH_EVP:
111 if (mac->evp_md == NULL)
112 return -1;
113 HMAC_Init(&mac->evp_ctx, mac->key, mac->key_len, mac->evp_md);
114 return 0;
115 case SSH_UMAC:
116 mac->umac_ctx = umac_new(mac->key);
117 return 0;
118 default:
119 return -1;
123 u_char *
124 mac_compute(Mac *mac, u_int32_t seqno, u_char *data, int datalen)
126 static u_char m[EVP_MAX_MD_SIZE];
127 u_char b[4], nonce[8];
129 if (mac->mac_len > sizeof(m))
130 fatal("mac_compute: mac too long %u %lu",
131 mac->mac_len, (u_long)sizeof(m));
133 switch (mac->type) {
134 case SSH_EVP:
135 put_u32(b, seqno);
136 /* reset HMAC context */
137 HMAC_Init(&mac->evp_ctx, NULL, 0, NULL);
138 HMAC_Update(&mac->evp_ctx, b, sizeof(b));
139 HMAC_Update(&mac->evp_ctx, data, datalen);
140 HMAC_Final(&mac->evp_ctx, m, NULL);
141 break;
142 case SSH_UMAC:
143 put_u64(nonce, seqno);
144 umac_update(mac->umac_ctx, data, datalen);
145 umac_final(mac->umac_ctx, m, nonce);
146 break;
147 default:
148 fatal("mac_compute: unknown MAC type");
150 return (m);
153 void
154 mac_clear(Mac *mac)
156 if (mac->type == SSH_UMAC) {
157 if (mac->umac_ctx != NULL)
158 umac_delete(mac->umac_ctx);
159 } else if (mac->evp_md != NULL)
160 HMAC_cleanup(&mac->evp_ctx);
161 mac->evp_md = NULL;
162 mac->umac_ctx = NULL;
165 /* XXX copied from ciphers_valid */
166 #define MAC_SEP ","
168 mac_valid(const char *names)
170 char *maclist, *cp, *p;
172 if (names == NULL || strcmp(names, "") == 0)
173 return (0);
174 maclist = cp = xstrdup(names);
175 for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0';
176 (p = strsep(&cp, MAC_SEP))) {
177 if (mac_setup(NULL, p) < 0) {
178 debug("bad mac %s [%s]", p, names);
179 xfree(maclist);
180 return (0);
181 } else {
182 debug3("mac ok: %s [%s]", p, names);
185 debug3("macs ok: [%s]", names);
186 xfree(maclist);
187 return (1);