1 /* $OpenBSD: mac.c,v 1.32 2015/01/15 18:32:54 naddy 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 <string.h>
31 #include <stdio.h>
32
33 #include "digest.h"
34 #include "hmac.h"
35 #include "umac.h"
36 #include "mac.h"
37 #include "misc.h"
38 #include "ssherr.h"
39 #include "sshbuf.h"
40
41 #include "openbsd-compat/openssl-compat.h"
42
43 #define SSH_DIGEST 1 /* SSH_DIGEST_XXX */
44 #define SSH_UMAC 2 /* UMAC (not integrated with OpenSSL) */
45 #define SSH_UMAC128 3
46
47 struct macalg {
48 char *name;
49 int type;
50 int alg;
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 */
55 };
56
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 },
64 #endif
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 #if defined(HAVE_EVP_RIPEMD)
68 { "hmac-ripemd160", SSH_DIGEST, SSH_DIGEST_RIPEMD160, 0, 0, 0, 0 },
69 { "hmac-ripemd160@openssh.com", SSH_DIGEST, SSH_DIGEST_RIPEMD160, 0, 0, 0, 0 },
70 #endif
71 { "umac-64@openssh.com", SSH_UMAC, 0, 0, 128, 64, 0 },
72 { "umac-128@openssh.com", SSH_UMAC128, 0, 0, 128, 128, 0 },
73
74 /* Encrypt-then-MAC variants */
75 { "hmac-sha1-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA1, 0, 0, 0, 1 },
76 { "hmac-sha1-96-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA1, 96, 0, 0, 1 },
77 #ifdef HAVE_EVP_SHA256
78 { "hmac-sha2-256-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA256, 0, 0, 0, 1 },
79 { "hmac-sha2-512-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA512, 0, 0, 0, 1 },
80 #endif
81 { "hmac-md5-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_MD5, 0, 0, 0, 1 },
82 { "hmac-md5-96-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_MD5, 96, 0, 0, 1 },
83 { "hmac-ripemd160-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_RIPEMD160, 0, 0, 0, 1 },
84 { "umac-64-etm@openssh.com", SSH_UMAC, 0, 0, 128, 64, 1 },
85 { "umac-128-etm@openssh.com", SSH_UMAC128, 0, 0, 128, 128, 1 },
86
87 { NULL, 0, 0, 0, 0, 0, 0 }
88 };
89
90 /* Returns a list of supported MACs separated by the specified char. */
91 char *
mac_alg_list(char sep)92 mac_alg_list(char sep)
93 {
94 char *ret = NULL, *tmp;
95 size_t nlen, rlen = 0;
96 const struct macalg *m;
97
98 for (m = macs; m->name != NULL; m++) {
99 if (ret != NULL)
100 ret[rlen++] = sep;
101 nlen = strlen(m->name);
102 if ((tmp = realloc(ret, rlen + nlen + 2)) == NULL) {
103 free(ret);
104 return NULL;
105 }
106 ret = tmp;
107 memcpy(ret + rlen, m->name, nlen + 1);
108 rlen += nlen;
109 }
110 return ret;
111 }
112
113 static int
mac_setup_by_alg(struct sshmac * mac,const struct macalg * macalg)114 mac_setup_by_alg(struct sshmac *mac, const struct macalg *macalg)
115 {
116 mac->type = macalg->type;
117 if (mac->type == SSH_DIGEST) {
118 if ((mac->hmac_ctx = ssh_hmac_start(macalg->alg)) == NULL)
119 return SSH_ERR_ALLOC_FAIL;
120 mac->key_len = mac->mac_len = ssh_hmac_bytes(macalg->alg);
121 } else {
122 mac->mac_len = macalg->len / 8;
123 mac->key_len = macalg->key_len / 8;
124 mac->umac_ctx = NULL;
125 }
126 if (macalg->truncatebits != 0)
127 mac->mac_len = macalg->truncatebits / 8;
128 mac->etm = macalg->etm;
129 return 0;
130 }
131
132 int
mac_setup(struct sshmac * mac,char * name)133 mac_setup(struct sshmac *mac, char *name)
134 {
135 const struct macalg *m;
136
137 for (m = macs; m->name != NULL; m++) {
138 if (strcmp(name, m->name) != 0)
139 continue;
140 if (mac != NULL)
141 return mac_setup_by_alg(mac, m);
142 return 0;
143 }
144 return SSH_ERR_INVALID_ARGUMENT;
145 }
146
147 int
mac_init(struct sshmac * mac)148 mac_init(struct sshmac *mac)
149 {
150 if (mac->key == NULL)
151 return SSH_ERR_INVALID_ARGUMENT;
152 switch (mac->type) {
153 case SSH_DIGEST:
154 if (mac->hmac_ctx == NULL ||
155 ssh_hmac_init(mac->hmac_ctx, mac->key, mac->key_len) < 0)
156 return SSH_ERR_INVALID_ARGUMENT;
157 return 0;
158 case SSH_UMAC:
159 if ((mac->umac_ctx = umac_new(mac->key)) == NULL)
160 return SSH_ERR_ALLOC_FAIL;
161 return 0;
162 case SSH_UMAC128:
163 if ((mac->umac_ctx = umac128_new(mac->key)) == NULL)
164 return SSH_ERR_ALLOC_FAIL;
165 return 0;
166 default:
167 return SSH_ERR_INVALID_ARGUMENT;
168 }
169 }
170
171 int
mac_compute(struct sshmac * mac,u_int32_t seqno,const u_char * data,int datalen,u_char * digest,size_t dlen)172 mac_compute(struct sshmac *mac, u_int32_t seqno, const u_char *data, int datalen,
173 u_char *digest, size_t dlen)
174 {
175 static union {
176 u_char m[SSH_DIGEST_MAX_LENGTH];
177 u_int64_t for_align;
178 } u;
179 u_char b[4];
180 u_char nonce[8];
181
182 if (mac->mac_len > sizeof(u))
183 return SSH_ERR_INTERNAL_ERROR;
184
185 switch (mac->type) {
186 case SSH_DIGEST:
187 put_u32(b, seqno);
188 /* reset HMAC context */
189 if (ssh_hmac_init(mac->hmac_ctx, NULL, 0) < 0 ||
190 ssh_hmac_update(mac->hmac_ctx, b, sizeof(b)) < 0 ||
191 ssh_hmac_update(mac->hmac_ctx, data, datalen) < 0 ||
192 ssh_hmac_final(mac->hmac_ctx, u.m, sizeof(u.m)) < 0)
193 return SSH_ERR_LIBCRYPTO_ERROR;
194 break;
195 case SSH_UMAC:
196 POKE_U64(nonce, seqno);
197 umac_update(mac->umac_ctx, data, datalen);
198 umac_final(mac->umac_ctx, u.m, nonce);
199 break;
200 case SSH_UMAC128:
201 put_u64(nonce, seqno);
202 umac128_update(mac->umac_ctx, data, datalen);
203 umac128_final(mac->umac_ctx, u.m, nonce);
204 break;
205 default:
206 return SSH_ERR_INVALID_ARGUMENT;
207 }
208 if (digest != NULL) {
209 if (dlen > mac->mac_len)
210 dlen = mac->mac_len;
211 memcpy(digest, u.m, dlen);
212 }
213 return 0;
214 }
215
216 void
mac_clear(struct sshmac * mac)217 mac_clear(struct sshmac *mac)
218 {
219 if (mac->type == SSH_UMAC) {
220 if (mac->umac_ctx != NULL)
221 umac_delete(mac->umac_ctx);
222 } else if (mac->type == SSH_UMAC128) {
223 if (mac->umac_ctx != NULL)
224 umac128_delete(mac->umac_ctx);
225 } else if (mac->hmac_ctx != NULL)
226 ssh_hmac_free(mac->hmac_ctx);
227 mac->hmac_ctx = NULL;
228 mac->umac_ctx = NULL;
229 }
230
231 /* XXX copied from ciphers_valid */
232 #define MAC_SEP ","
233 int
mac_valid(const char * names)234 mac_valid(const char *names)
235 {
236 char *maclist, *cp, *p;
237
238 if (names == NULL || strcmp(names, "") == 0)
239 return 0;
240 if ((maclist = cp = strdup(names)) == NULL)
241 return 0;
242 for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0';
243 (p = strsep(&cp, MAC_SEP))) {
244 if (mac_setup(NULL, p) < 0) {
245 free(maclist);
246 return 0;
247 }
248 }
249 free(maclist);
250 return 1;
251 }
252