Annotation of src/usr.bin/ssh/mac.c, Revision 1.25
1.25 ! dtucker 1: /* $OpenBSD: mac.c,v 1.24 2013/06/03 00:03:18 dtucker Exp $ */
1.1 markus 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:
1.12 deraadt 26: #include <sys/types.h>
1.1 markus 27:
28: #include <openssl/hmac.h>
1.11 stevesk 29:
30: #include <string.h>
1.12 deraadt 31: #include <signal.h>
1.1 markus 32:
33: #include "xmalloc.h"
34: #include "log.h"
35: #include "cipher.h"
1.12 deraadt 36: #include "buffer.h"
37: #include "key.h"
1.1 markus 38: #include "kex.h"
39: #include "mac.h"
1.10 djm 40: #include "misc.h"
1.1 markus 41:
1.14 pvalchev 42: #include "umac.h"
43:
44: #define SSH_EVP 1 /* OpenSSL EVP-based MAC */
45: #define SSH_UMAC 2 /* UMAC (not integrated with OpenSSL) */
1.19 markus 46: #define SSH_UMAC128 3
1.14 pvalchev 47:
1.22 djm 48: struct macalg {
1.1 markus 49: char *name;
1.14 pvalchev 50: int type;
1.5 markus 51: const EVP_MD * (*mdfunc)(void);
1.1 markus 52: int truncatebits; /* truncate digest if != 0 */
1.14 pvalchev 53: int key_len; /* just for UMAC */
54: int len; /* just for UMAC */
1.20 markus 55: int etm; /* Encrypt-then-MAC */
1.22 djm 56: };
57:
58: static const struct macalg macs[] = {
1.20 markus 59: /* Encrypt-and-MAC (encrypt-and-authenticate) variants */
60: { "hmac-sha1", SSH_EVP, EVP_sha1, 0, 0, 0, 0 },
61: { "hmac-sha1-96", SSH_EVP, EVP_sha1, 96, 0, 0, 0 },
62: { "hmac-sha2-256", SSH_EVP, EVP_sha256, 0, 0, 0, 0 },
63: { "hmac-sha2-512", SSH_EVP, EVP_sha512, 0, 0, 0, 0 },
64: { "hmac-md5", SSH_EVP, EVP_md5, 0, 0, 0, 0 },
65: { "hmac-md5-96", SSH_EVP, EVP_md5, 96, 0, 0, 0 },
66: { "hmac-ripemd160", SSH_EVP, EVP_ripemd160, 0, 0, 0, 0 },
67: { "hmac-ripemd160@openssh.com", SSH_EVP, EVP_ripemd160, 0, 0, 0, 0 },
68: { "umac-64@openssh.com", SSH_UMAC, NULL, 0, 128, 64, 0 },
69: { "umac-128@openssh.com", SSH_UMAC128, NULL, 0, 128, 128, 0 },
70:
71: /* Encrypt-then-MAC variants */
72: { "hmac-sha1-etm@openssh.com", SSH_EVP, EVP_sha1, 0, 0, 0, 1 },
73: { "hmac-sha1-96-etm@openssh.com", SSH_EVP, EVP_sha1, 96, 0, 0, 1 },
74: { "hmac-sha2-256-etm@openssh.com", SSH_EVP, EVP_sha256, 0, 0, 0, 1 },
75: { "hmac-sha2-512-etm@openssh.com", SSH_EVP, EVP_sha512, 0, 0, 0, 1 },
76: { "hmac-md5-etm@openssh.com", SSH_EVP, EVP_md5, 0, 0, 0, 1 },
77: { "hmac-md5-96-etm@openssh.com", SSH_EVP, EVP_md5, 96, 0, 0, 1 },
1.21 sthen 78: { "hmac-ripemd160-etm@openssh.com", SSH_EVP, EVP_ripemd160, 0, 0, 0, 1 },
1.20 markus 79: { "umac-64-etm@openssh.com", SSH_UMAC, NULL, 0, 128, 64, 1 },
80: { "umac-128-etm@openssh.com", SSH_UMAC128, NULL, 0, 128, 128, 1 },
81:
82: { NULL, 0, NULL, 0, 0, 0, 0 }
1.1 markus 83: };
84:
1.25 ! dtucker 85: /* Returns a list of supported MACs separated by the specified char. */
1.22 djm 86: char *
1.25 ! dtucker 87: mac_alg_list(char sep)
1.22 djm 88: {
89: char *ret = NULL;
90: size_t nlen, rlen = 0;
91: const struct macalg *m;
92:
93: for (m = macs; m->name != NULL; m++) {
94: if (ret != NULL)
1.25 ! dtucker 95: ret[rlen++] = sep;
1.22 djm 96: nlen = strlen(m->name);
97: ret = xrealloc(ret, 1, rlen + nlen + 2);
98: memcpy(ret + rlen, m->name, nlen + 1);
99: rlen += nlen;
100: }
101: return ret;
102: }
103:
1.14 pvalchev 104: static void
1.22 djm 105: mac_setup_by_alg(Mac *mac, const struct macalg *macalg)
1.14 pvalchev 106: {
107: int evp_len;
1.22 djm 108:
109: mac->type = macalg->type;
1.14 pvalchev 110: if (mac->type == SSH_EVP) {
1.22 djm 111: mac->evp_md = macalg->mdfunc();
1.14 pvalchev 112: if ((evp_len = EVP_MD_size(mac->evp_md)) <= 0)
113: fatal("mac %s len %d", mac->name, evp_len);
114: mac->key_len = mac->mac_len = (u_int)evp_len;
115: } else {
1.22 djm 116: mac->mac_len = macalg->len / 8;
117: mac->key_len = macalg->key_len / 8;
1.14 pvalchev 118: mac->umac_ctx = NULL;
119: }
1.22 djm 120: if (macalg->truncatebits != 0)
121: mac->mac_len = macalg->truncatebits / 8;
122: mac->etm = macalg->etm;
1.14 pvalchev 123: }
124:
1.1 markus 125: int
1.13 djm 126: mac_setup(Mac *mac, char *name)
1.1 markus 127: {
1.22 djm 128: const struct macalg *m;
1.7 djm 129:
1.22 djm 130: for (m = macs; m->name != NULL; m++) {
131: if (strcmp(name, m->name) != 0)
132: continue;
133: if (mac != NULL)
134: mac_setup_by_alg(mac, m);
135: debug2("mac_setup: found %s", name);
136: return (0);
1.1 markus 137: }
1.13 djm 138: debug2("mac_setup: unknown %s", name);
1.1 markus 139: return (-1);
140: }
141:
1.14 pvalchev 142: int
1.13 djm 143: mac_init(Mac *mac)
144: {
145: if (mac->key == NULL)
146: fatal("mac_init: no key");
1.14 pvalchev 147: switch (mac->type) {
148: case SSH_EVP:
149: if (mac->evp_md == NULL)
150: return -1;
1.17 djm 151: HMAC_CTX_init(&mac->evp_ctx);
1.14 pvalchev 152: HMAC_Init(&mac->evp_ctx, mac->key, mac->key_len, mac->evp_md);
153: return 0;
154: case SSH_UMAC:
155: mac->umac_ctx = umac_new(mac->key);
156: return 0;
1.19 markus 157: case SSH_UMAC128:
158: mac->umac_ctx = umac128_new(mac->key);
159: return 0;
1.14 pvalchev 160: default:
161: return -1;
162: }
1.13 djm 163: }
164:
1.1 markus 165: u_char *
166: mac_compute(Mac *mac, u_int32_t seqno, u_char *data, int datalen)
167: {
1.24 dtucker 168: static union {
169: u_char m[EVP_MAX_MD_SIZE];
170: u_int64_t for_align;
171: } u;
1.14 pvalchev 172: u_char b[4], nonce[8];
1.1 markus 173:
1.24 dtucker 174: if (mac->mac_len > sizeof(u))
1.14 pvalchev 175: fatal("mac_compute: mac too long %u %lu",
1.24 dtucker 176: mac->mac_len, (u_long)sizeof(u));
1.14 pvalchev 177:
178: switch (mac->type) {
179: case SSH_EVP:
180: put_u32(b, seqno);
181: /* reset HMAC context */
182: HMAC_Init(&mac->evp_ctx, NULL, 0, NULL);
183: HMAC_Update(&mac->evp_ctx, b, sizeof(b));
184: HMAC_Update(&mac->evp_ctx, data, datalen);
1.24 dtucker 185: HMAC_Final(&mac->evp_ctx, u.m, NULL);
1.14 pvalchev 186: break;
187: case SSH_UMAC:
188: put_u64(nonce, seqno);
189: umac_update(mac->umac_ctx, data, datalen);
1.24 dtucker 190: umac_final(mac->umac_ctx, u.m, nonce);
1.14 pvalchev 191: break;
1.19 markus 192: case SSH_UMAC128:
193: put_u64(nonce, seqno);
194: umac128_update(mac->umac_ctx, data, datalen);
1.24 dtucker 195: umac128_final(mac->umac_ctx, u.m, nonce);
1.19 markus 196: break;
1.14 pvalchev 197: default:
198: fatal("mac_compute: unknown MAC type");
199: }
1.24 dtucker 200: return (u.m);
1.1 markus 201: }
202:
1.13 djm 203: void
204: mac_clear(Mac *mac)
205: {
1.14 pvalchev 206: if (mac->type == SSH_UMAC) {
207: if (mac->umac_ctx != NULL)
208: umac_delete(mac->umac_ctx);
1.19 markus 209: } else if (mac->type == SSH_UMAC128) {
210: if (mac->umac_ctx != NULL)
211: umac128_delete(mac->umac_ctx);
1.14 pvalchev 212: } else if (mac->evp_md != NULL)
213: HMAC_cleanup(&mac->evp_ctx);
214: mac->evp_md = NULL;
215: mac->umac_ctx = NULL;
1.13 djm 216: }
217:
1.1 markus 218: /* XXX copied from ciphers_valid */
219: #define MAC_SEP ","
220: int
221: mac_valid(const char *names)
222: {
223: char *maclist, *cp, *p;
224:
225: if (names == NULL || strcmp(names, "") == 0)
226: return (0);
227: maclist = cp = xstrdup(names);
228: for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0';
1.3 deraadt 229: (p = strsep(&cp, MAC_SEP))) {
1.13 djm 230: if (mac_setup(NULL, p) < 0) {
1.1 markus 231: debug("bad mac %s [%s]", p, names);
1.23 djm 232: free(maclist);
1.1 markus 233: return (0);
234: } else {
235: debug3("mac ok: %s [%s]", p, names);
236: }
237: }
238: debug3("macs ok: [%s]", names);
1.23 djm 239: free(maclist);
1.1 markus 240: return (1);
241: }
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