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.
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 <sys/types.h>
27
28 #include <openssl/hmac.h>
29
30 #include <string.h>
31 #include <signal.h>
32
33 #include "xmalloc.h"
34 #include "log.h"
35 #include "cipher.h"
36 #include "buffer.h"
37 #include "key.h"
38 #include "kex.h"
39 #include "mac.h"
40 #include "misc.h"
41
42 __RCSID("$MirOS: src/usr.bin/ssh/mac.c,v 1.7 2008/12/16 20:55:23 tg Exp $");
43
44 #include "umac.h"
45
46 #define SSH_EVP 1 /* OpenSSL EVP-based MAC */
47 #define SSH_UMAC 2 /* UMAC (not integrated with OpenSSL) */
48
49 struct {
50 const char *name;
51 int type;
52 const EVP_MD * (*mdfunc)(void);
53 int truncatebits; /* truncate digest if != 0 */
54 int key_len; /* just for UMAC */
55 int len; /* just for UMAC */
56 } macs[] = {
57 { "hmac-sha1", SSH_EVP, EVP_sha1, 0, -1, -1 },
58 { "hmac-sha1-96", SSH_EVP, EVP_sha1, 96, -1, -1 },
59 { "hmac-md5", SSH_EVP, EVP_md5, 0, -1, -1 },
60 { "hmac-md5-96", SSH_EVP, EVP_md5, 96, -1, -1 },
61 { "hmac-ripemd160", SSH_EVP, EVP_ripemd160, 0, -1, -1 },
62 { "hmac-ripemd160@openssh.com", SSH_EVP, EVP_ripemd160, 0, -1, -1 },
63 { "umac-64@openssh.com", SSH_UMAC, NULL, 0, 128, 64 },
64 { NULL, 0, NULL, 0, -1, -1 }
65 };
66
67 static void
mac_setup_by_id(Mac * mac,int which)68 mac_setup_by_id(Mac *mac, int which)
69 {
70 int evp_len;
71 mac->type = macs[which].type;
72 if (mac->type == SSH_EVP) {
73 mac->evp_md = (*macs[which].mdfunc)();
74 if ((evp_len = EVP_MD_size(mac->evp_md)) <= 0)
75 fatal("mac %s len %d", mac->name, evp_len);
76 mac->key_len = mac->mac_len = (u_int)evp_len;
77 } else {
78 mac->mac_len = macs[which].len / 8;
79 mac->key_len = macs[which].key_len / 8;
80 mac->umac_ctx = NULL;
81 }
82 if (macs[which].truncatebits != 0)
83 mac->mac_len = macs[which].truncatebits / 8;
84 }
85
86 int
mac_setup(Mac * mac,char * name)87 mac_setup(Mac *mac, char *name)
88 {
89 int i;
90
91 for (i = 0; macs[i].name; i++) {
92 if (strcmp(name, macs[i].name) == 0) {
93 if (mac != NULL)
94 mac_setup_by_id(mac, i);
95 debug2("mac_setup: found %s", name);
96 return (0);
97 }
98 }
99 debug2("mac_setup: unknown %s", name);
100 return (-1);
101 }
102
103 int
mac_init(Mac * mac)104 mac_init(Mac *mac)
105 {
106 if (mac->key == NULL)
107 fatal("mac_init: no key");
108 switch (mac->type) {
109 case SSH_EVP:
110 if (mac->evp_md == NULL)
111 return -1;
112 HMAC_Init(&mac->evp_ctx, mac->key, mac->key_len, mac->evp_md);
113 return 0;
114 case SSH_UMAC:
115 mac->umac_ctx = umac_new(mac->key);
116 return 0;
117 default:
118 return -1;
119 }
120 }
121
122 u_char *
mac_compute(Mac * mac,u_int32_t seqno,u_char * data,int datalen)123 mac_compute(Mac *mac, u_int32_t seqno, u_char *data, int datalen)
124 {
125 static u_char m[EVP_MAX_MD_SIZE];
126 u_char b[4], nonce[8];
127
128 if (mac->mac_len > sizeof(m))
129 fatal("mac_compute: mac too long %u %lu",
130 mac->mac_len, (u_long)sizeof(m));
131
132 switch (mac->type) {
133 case SSH_EVP:
134 put_u32(b, seqno);
135 /* reset HMAC context */
136 HMAC_Init(&mac->evp_ctx, NULL, 0, NULL);
137 HMAC_Update(&mac->evp_ctx, b, sizeof(b));
138 HMAC_Update(&mac->evp_ctx, data, datalen);
139 HMAC_Final(&mac->evp_ctx, m, NULL);
140 break;
141 case SSH_UMAC:
142 put_u64(nonce, seqno);
143 umac_update(mac->umac_ctx, data, datalen);
144 umac_final(mac->umac_ctx, m, nonce);
145 break;
146 default:
147 fatal("mac_compute: unknown MAC type");
148 }
149 return (m);
150 }
151
152 void
mac_clear(Mac * mac)153 mac_clear(Mac *mac)
154 {
155 if (mac->type == SSH_UMAC) {
156 if (mac->umac_ctx != NULL)
157 umac_delete(mac->umac_ctx);
158 } else if (mac->evp_md != NULL)
159 HMAC_cleanup(&mac->evp_ctx);
160 mac->evp_md = NULL;
161 mac->umac_ctx = NULL;
162 }
163
164 /* XXX copied from ciphers_valid */
165 #define MAC_SEP ","
166 int
mac_valid(const char * names)167 mac_valid(const char *names)
168 {
169 char *maclist, *cp, *p;
170
171 if (names == NULL || strcmp(names, "") == 0)
172 return (0);
173 maclist = cp = xstrdup(names);
174 for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0';
175 (p = strsep(&cp, MAC_SEP))) {
176 if (mac_setup(NULL, p) < 0) {
177 debug("bad mac %s [%s]", p, names);
178 xfree(maclist);
179 return (0);
180 } else {
181 debug3("mac ok: %s [%s]", p, names);
182 }
183 }
184 debug3("macs ok: [%s]", names);
185 xfree(maclist);
186 return (1);
187 }
188