1 /* $OpenBSD: mac.c,v 1.16 2011/08/02 01:22:11 djm 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 #include "umac.h"
46
47 #define SSH_EVP 1 /* OpenSSL EVP-based MAC */
48 #define SSH_UMAC 2 /* UMAC (not integrated with OpenSSL) */
49
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 #ifdef HAVE_EVP_SHA256
61 { "hmac-sha2-256", SSH_EVP, EVP_sha256, 0, -1, -1 },
62 { "hmac-sha2-256-96", SSH_EVP, EVP_sha256, 96, -1, -1 },
63 { "hmac-sha2-512", SSH_EVP, EVP_sha512, 0, -1, -1 },
64 { "hmac-sha2-512-96", SSH_EVP, EVP_sha512, 96, -1, -1 },
65 #endif
66 { "hmac-md5", SSH_EVP, EVP_md5, 0, -1, -1 },
67 { "hmac-md5-96", SSH_EVP, EVP_md5, 96, -1, -1 },
68 { "hmac-ripemd160", SSH_EVP, EVP_ripemd160, 0, -1, -1 },
69 { "hmac-ripemd160@openssh.com", SSH_EVP, EVP_ripemd160, 0, -1, -1 },
70 { "umac-64@openssh.com", SSH_UMAC, NULL, 0, 128, 64 },
71 { NULL, 0, NULL, 0, -1, -1 }
72 };
73
74 static void
mac_setup_by_id(Mac * mac,int which)75 mac_setup_by_id(Mac *mac, int which)
76 {
77 int evp_len;
78 mac->type = macs[which].type;
79 if (mac->type == SSH_EVP) {
80 mac->evp_md = (*macs[which].mdfunc)();
81 if ((evp_len = EVP_MD_size(mac->evp_md)) <= 0)
82 fatal("mac %s len %d", mac->name, evp_len);
83 mac->key_len = mac->mac_len = (u_int)evp_len;
84 } else {
85 mac->mac_len = macs[which].len / 8;
86 mac->key_len = macs[which].key_len / 8;
87 mac->umac_ctx = NULL;
88 }
89 if (macs[which].truncatebits != 0)
90 mac->mac_len = macs[which].truncatebits / 8;
91 }
92
93 int
mac_setup(Mac * mac,char * name)94 mac_setup(Mac *mac, char *name)
95 {
96 int i;
97
98 for (i = 0; macs[i].name; i++) {
99 if (strcmp(name, macs[i].name) == 0) {
100 if (mac != NULL)
101 mac_setup_by_id(mac, i);
102 debug2("mac_setup: found %s", name);
103 return (0);
104 }
105 }
106 debug2("mac_setup: unknown %s", name);
107 return (-1);
108 }
109
110 int
mac_init(Mac * mac)111 mac_init(Mac *mac)
112 {
113 if (mac->key == NULL)
114 fatal("mac_init: no key");
115 switch (mac->type) {
116 case SSH_EVP:
117 if (mac->evp_md == NULL)
118 return -1;
119 HMAC_Init(&mac->evp_ctx, mac->key, mac->key_len, mac->evp_md);
120 return 0;
121 case SSH_UMAC:
122 mac->umac_ctx = umac_new(mac->key);
123 return 0;
124 default:
125 return -1;
126 }
127 }
128
129 u_char *
mac_compute(Mac * mac,u_int32_t seqno,u_char * data,int datalen)130 mac_compute(Mac *mac, u_int32_t seqno, u_char *data, int datalen)
131 {
132 static u_char m[EVP_MAX_MD_SIZE];
133 u_char b[4], nonce[8];
134
135 if (mac->mac_len > sizeof(m))
136 fatal("mac_compute: mac too long %u %lu",
137 mac->mac_len, (u_long)sizeof(m));
138
139 switch (mac->type) {
140 case SSH_EVP:
141 put_u32(b, seqno);
142 /* reset HMAC context */
143 HMAC_Init(&mac->evp_ctx, NULL, 0, NULL);
144 HMAC_Update(&mac->evp_ctx, b, sizeof(b));
145 HMAC_Update(&mac->evp_ctx, data, datalen);
146 HMAC_Final(&mac->evp_ctx, m, NULL);
147 break;
148 case SSH_UMAC:
149 put_u64(nonce, seqno);
150 umac_update(mac->umac_ctx, data, datalen);
151 umac_final(mac->umac_ctx, m, nonce);
152 break;
153 default:
154 fatal("mac_compute: unknown MAC type");
155 }
156 return (m);
157 }
158
159 void
mac_clear(Mac * mac)160 mac_clear(Mac *mac)
161 {
162 if (mac->type == SSH_UMAC) {
163 if (mac->umac_ctx != NULL)
164 umac_delete(mac->umac_ctx);
165 } else if (mac->evp_md != NULL)
166 HMAC_cleanup(&mac->evp_ctx);
167 mac->evp_md = NULL;
168 mac->umac_ctx = NULL;
169 }
170
171 /* XXX copied from ciphers_valid */
172 #define MAC_SEP ","
173 int
mac_valid(const char * names)174 mac_valid(const char *names)
175 {
176 char *maclist, *cp, *p;
177
178 if (names == NULL || strcmp(names, "") == 0)
179 return (0);
180 maclist = cp = xstrdup(names);
181 for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0';
182 (p = strsep(&cp, MAC_SEP))) {
183 if (mac_setup(NULL, p) < 0) {
184 debug("bad mac %s [%s]", p, names);
185 xfree(maclist);
186 return (0);
187 } else {
188 debug3("mac ok: %s [%s]", p, names);
189 }
190 }
191 debug3("macs ok: [%s]", names);
192 xfree(maclist);
193 return (1);
194 }
195