1 /* $OpenBSD: mac.c,v 1.34 2017/05/08 22:57:38 djm Exp $ */
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
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.
28 #include <sys/types.h>
41 #include "openbsd-compat/openssl-compat.h"
43 #define SSH_DIGEST 1 /* SSH_DIGEST_XXX */
44 #define SSH_UMAC 2 /* UMAC (not integrated with OpenSSL) */
51 int truncatebits; /* truncate digest if != 0 */
52 int key_len; /* just for UMAC */
53 int len; /* just for UMAC */
54 int etm; /* Encrypt-then-MAC */
57 static const struct macalg macs[] = {
58 /* Encrypt-and-MAC (encrypt-and-authenticate) variants */
59 { "hmac-sha1", SSH_DIGEST, SSH_DIGEST_SHA1, 0, 0, 0, 0 },
60 { "hmac-sha1-96", SSH_DIGEST, SSH_DIGEST_SHA1, 96, 0, 0, 0 },
61 #ifdef HAVE_EVP_SHA256
62 { "hmac-sha2-256", SSH_DIGEST, SSH_DIGEST_SHA256, 0, 0, 0, 0 },
63 { "hmac-sha2-512", SSH_DIGEST, SSH_DIGEST_SHA512, 0, 0, 0, 0 },
65 { "hmac-md5", SSH_DIGEST, SSH_DIGEST_MD5, 0, 0, 0, 0 },
66 { "hmac-md5-96", SSH_DIGEST, SSH_DIGEST_MD5, 96, 0, 0, 0 },
67 { "umac-64@openssh.com", SSH_UMAC, 0, 0, 128, 64, 0 },
68 { "umac-128@openssh.com", SSH_UMAC128, 0, 0, 128, 128, 0 },
70 /* Encrypt-then-MAC variants */
71 { "hmac-sha1-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA1, 0, 0, 0, 1 },
72 { "hmac-sha1-96-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA1, 96, 0, 0, 1 },
73 #ifdef HAVE_EVP_SHA256
74 { "hmac-sha2-256-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA256, 0, 0, 0, 1 },
75 { "hmac-sha2-512-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA512, 0, 0, 0, 1 },
77 { "hmac-md5-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_MD5, 0, 0, 0, 1 },
78 { "hmac-md5-96-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_MD5, 96, 0, 0, 1 },
79 { "umac-64-etm@openssh.com", SSH_UMAC, 0, 0, 128, 64, 1 },
80 { "umac-128-etm@openssh.com", SSH_UMAC128, 0, 0, 128, 128, 1 },
82 { NULL, 0, 0, 0, 0, 0, 0 }
85 /* Returns a list of supported MACs separated by the specified char. */
87 mac_alg_list(char sep)
89 char *ret = NULL, *tmp;
90 size_t nlen, rlen = 0;
91 const struct macalg *m;
93 for (m = macs; m->name != NULL; m++) {
96 nlen = strlen(m->name);
97 if ((tmp = realloc(ret, rlen + nlen + 2)) == NULL) {
102 memcpy(ret + rlen, m->name, nlen + 1);
109 mac_setup_by_alg(struct sshmac *mac, const struct macalg *macalg)
111 mac->type = macalg->type;
112 if (mac->type == SSH_DIGEST) {
113 if ((mac->hmac_ctx = ssh_hmac_start(macalg->alg)) == NULL)
114 return SSH_ERR_ALLOC_FAIL;
115 mac->key_len = mac->mac_len = ssh_hmac_bytes(macalg->alg);
117 mac->mac_len = macalg->len / 8;
118 mac->key_len = macalg->key_len / 8;
119 mac->umac_ctx = NULL;
121 if (macalg->truncatebits != 0)
122 mac->mac_len = macalg->truncatebits / 8;
123 mac->etm = macalg->etm;
128 mac_setup(struct sshmac *mac, char *name)
130 const struct macalg *m;
132 for (m = macs; m->name != NULL; m++) {
133 if (strcmp(name, m->name) != 0)
136 return mac_setup_by_alg(mac, m);
139 return SSH_ERR_INVALID_ARGUMENT;
143 mac_init(struct sshmac *mac)
145 if (mac->key == NULL)
146 return SSH_ERR_INVALID_ARGUMENT;
149 if (mac->hmac_ctx == NULL ||
150 ssh_hmac_init(mac->hmac_ctx, mac->key, mac->key_len) < 0)
151 return SSH_ERR_INVALID_ARGUMENT;
154 if ((mac->umac_ctx = umac_new(mac->key)) == NULL)
155 return SSH_ERR_ALLOC_FAIL;
158 if ((mac->umac_ctx = umac128_new(mac->key)) == NULL)
159 return SSH_ERR_ALLOC_FAIL;
162 return SSH_ERR_INVALID_ARGUMENT;
167 mac_compute(struct sshmac *mac, u_int32_t seqno,
168 const u_char *data, int datalen,
169 u_char *digest, size_t dlen)
172 u_char m[SSH_DIGEST_MAX_LENGTH];
178 if (mac->mac_len > sizeof(u))
179 return SSH_ERR_INTERNAL_ERROR;
184 /* reset HMAC context */
185 if (ssh_hmac_init(mac->hmac_ctx, NULL, 0) < 0 ||
186 ssh_hmac_update(mac->hmac_ctx, b, sizeof(b)) < 0 ||
187 ssh_hmac_update(mac->hmac_ctx, data, datalen) < 0 ||
188 ssh_hmac_final(mac->hmac_ctx, u.m, sizeof(u.m)) < 0)
189 return SSH_ERR_LIBCRYPTO_ERROR;
192 POKE_U64(nonce, seqno);
193 umac_update(mac->umac_ctx, data, datalen);
194 umac_final(mac->umac_ctx, u.m, nonce);
197 put_u64(nonce, seqno);
198 umac128_update(mac->umac_ctx, data, datalen);
199 umac128_final(mac->umac_ctx, u.m, nonce);
202 return SSH_ERR_INVALID_ARGUMENT;
204 if (digest != NULL) {
205 if (dlen > mac->mac_len)
207 memcpy(digest, u.m, dlen);
213 mac_check(struct sshmac *mac, u_int32_t seqno,
214 const u_char *data, size_t dlen,
215 const u_char *theirmac, size_t mlen)
217 u_char ourmac[SSH_DIGEST_MAX_LENGTH];
220 if (mac->mac_len > mlen)
221 return SSH_ERR_INVALID_ARGUMENT;
222 if ((r = mac_compute(mac, seqno, data, dlen,
223 ourmac, sizeof(ourmac))) != 0)
225 if (timingsafe_bcmp(ourmac, theirmac, mac->mac_len) != 0)
226 return SSH_ERR_MAC_INVALID;
231 mac_clear(struct sshmac *mac)
233 if (mac->type == SSH_UMAC) {
234 if (mac->umac_ctx != NULL)
235 umac_delete(mac->umac_ctx);
236 } else if (mac->type == SSH_UMAC128) {
237 if (mac->umac_ctx != NULL)
238 umac128_delete(mac->umac_ctx);
239 } else if (mac->hmac_ctx != NULL)
240 ssh_hmac_free(mac->hmac_ctx);
241 mac->hmac_ctx = NULL;
242 mac->umac_ctx = NULL;
245 /* XXX copied from ciphers_valid */
248 mac_valid(const char *names)
250 char *maclist, *cp, *p;
252 if (names == NULL || strcmp(names, "") == 0)
254 if ((maclist = cp = strdup(names)) == NULL)
256 for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0';
257 (p = strsep(&cp, MAC_SEP))) {
258 if (mac_setup(NULL, p) < 0) {