Annotation of src/usr.bin/ssh/mac.c, Revision 1.34
1.34 ! djm 1: /* $OpenBSD: mac.c,v 1.33 2016/07/08 03:44:42 djm 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:
1.11 stevesk 28: #include <string.h>
1.31 markus 29: #include <stdio.h>
1.1 markus 30:
1.27 markus 31: #include "digest.h"
32: #include "hmac.h"
1.14 pvalchev 33: #include "umac.h"
1.31 markus 34: #include "mac.h"
35: #include "misc.h"
36: #include "ssherr.h"
37: #include "sshbuf.h"
1.14 pvalchev 38:
1.27 markus 39: #define SSH_DIGEST 1 /* SSH_DIGEST_XXX */
1.14 pvalchev 40: #define SSH_UMAC 2 /* UMAC (not integrated with OpenSSL) */
1.19 markus 41: #define SSH_UMAC128 3
1.14 pvalchev 42:
1.22 djm 43: struct macalg {
1.1 markus 44: char *name;
1.14 pvalchev 45: int type;
1.27 markus 46: int alg;
1.1 markus 47: int truncatebits; /* truncate digest if != 0 */
1.14 pvalchev 48: int key_len; /* just for UMAC */
49: int len; /* just for UMAC */
1.20 markus 50: int etm; /* Encrypt-then-MAC */
1.22 djm 51: };
52:
53: static const struct macalg macs[] = {
1.20 markus 54: /* Encrypt-and-MAC (encrypt-and-authenticate) variants */
1.27 markus 55: { "hmac-sha1", SSH_DIGEST, SSH_DIGEST_SHA1, 0, 0, 0, 0 },
56: { "hmac-sha1-96", SSH_DIGEST, SSH_DIGEST_SHA1, 96, 0, 0, 0 },
57: { "hmac-sha2-256", SSH_DIGEST, SSH_DIGEST_SHA256, 0, 0, 0, 0 },
58: { "hmac-sha2-512", SSH_DIGEST, SSH_DIGEST_SHA512, 0, 0, 0, 0 },
59: { "hmac-md5", SSH_DIGEST, SSH_DIGEST_MD5, 0, 0, 0, 0 },
60: { "hmac-md5-96", SSH_DIGEST, SSH_DIGEST_MD5, 96, 0, 0, 0 },
61: { "umac-64@openssh.com", SSH_UMAC, 0, 0, 128, 64, 0 },
62: { "umac-128@openssh.com", SSH_UMAC128, 0, 0, 128, 128, 0 },
1.20 markus 63:
64: /* Encrypt-then-MAC variants */
1.27 markus 65: { "hmac-sha1-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA1, 0, 0, 0, 1 },
66: { "hmac-sha1-96-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA1, 96, 0, 0, 1 },
67: { "hmac-sha2-256-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA256, 0, 0, 0, 1 },
68: { "hmac-sha2-512-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA512, 0, 0, 0, 1 },
69: { "hmac-md5-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_MD5, 0, 0, 0, 1 },
70: { "hmac-md5-96-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_MD5, 96, 0, 0, 1 },
71: { "umac-64-etm@openssh.com", SSH_UMAC, 0, 0, 128, 64, 1 },
72: { "umac-128-etm@openssh.com", SSH_UMAC128, 0, 0, 128, 128, 1 },
1.20 markus 73:
1.27 markus 74: { NULL, 0, 0, 0, 0, 0, 0 }
1.1 markus 75: };
76:
1.25 dtucker 77: /* Returns a list of supported MACs separated by the specified char. */
1.22 djm 78: char *
1.25 dtucker 79: mac_alg_list(char sep)
1.22 djm 80: {
1.31 markus 81: char *ret = NULL, *tmp;
1.22 djm 82: size_t nlen, rlen = 0;
83: const struct macalg *m;
84:
85: for (m = macs; m->name != NULL; m++) {
86: if (ret != NULL)
1.25 dtucker 87: ret[rlen++] = sep;
1.22 djm 88: nlen = strlen(m->name);
1.31 markus 89: if ((tmp = realloc(ret, rlen + nlen + 2)) == NULL) {
90: free(ret);
91: return NULL;
92: }
93: ret = tmp;
1.22 djm 94: memcpy(ret + rlen, m->name, nlen + 1);
95: rlen += nlen;
96: }
97: return ret;
98: }
99:
1.31 markus 100: static int
101: mac_setup_by_alg(struct sshmac *mac, const struct macalg *macalg)
1.14 pvalchev 102: {
1.22 djm 103: mac->type = macalg->type;
1.27 markus 104: if (mac->type == SSH_DIGEST) {
105: if ((mac->hmac_ctx = ssh_hmac_start(macalg->alg)) == NULL)
1.31 markus 106: return SSH_ERR_ALLOC_FAIL;
1.27 markus 107: mac->key_len = mac->mac_len = ssh_hmac_bytes(macalg->alg);
1.14 pvalchev 108: } else {
1.22 djm 109: mac->mac_len = macalg->len / 8;
110: mac->key_len = macalg->key_len / 8;
1.14 pvalchev 111: mac->umac_ctx = NULL;
112: }
1.22 djm 113: if (macalg->truncatebits != 0)
114: mac->mac_len = macalg->truncatebits / 8;
115: mac->etm = macalg->etm;
1.31 markus 116: return 0;
1.14 pvalchev 117: }
118:
1.1 markus 119: int
1.31 markus 120: mac_setup(struct sshmac *mac, char *name)
1.1 markus 121: {
1.22 djm 122: const struct macalg *m;
1.7 djm 123:
1.22 djm 124: for (m = macs; m->name != NULL; m++) {
125: if (strcmp(name, m->name) != 0)
126: continue;
1.31 markus 127: if (mac != NULL)
128: return mac_setup_by_alg(mac, m);
129: return 0;
1.1 markus 130: }
1.31 markus 131: return SSH_ERR_INVALID_ARGUMENT;
1.1 markus 132: }
133:
1.14 pvalchev 134: int
1.31 markus 135: mac_init(struct sshmac *mac)
1.13 djm 136: {
137: if (mac->key == NULL)
1.31 markus 138: return SSH_ERR_INVALID_ARGUMENT;
1.14 pvalchev 139: switch (mac->type) {
1.27 markus 140: case SSH_DIGEST:
141: if (mac->hmac_ctx == NULL ||
142: ssh_hmac_init(mac->hmac_ctx, mac->key, mac->key_len) < 0)
1.31 markus 143: return SSH_ERR_INVALID_ARGUMENT;
1.14 pvalchev 144: return 0;
145: case SSH_UMAC:
1.31 markus 146: if ((mac->umac_ctx = umac_new(mac->key)) == NULL)
147: return SSH_ERR_ALLOC_FAIL;
1.14 pvalchev 148: return 0;
1.19 markus 149: case SSH_UMAC128:
1.32 naddy 150: if ((mac->umac_ctx = umac128_new(mac->key)) == NULL)
151: return SSH_ERR_ALLOC_FAIL;
1.19 markus 152: return 0;
1.14 pvalchev 153: default:
1.31 markus 154: return SSH_ERR_INVALID_ARGUMENT;
1.14 pvalchev 155: }
1.13 djm 156: }
157:
1.31 markus 158: int
1.33 djm 159: mac_compute(struct sshmac *mac, u_int32_t seqno,
160: const u_char *data, int datalen,
1.31 markus 161: u_char *digest, size_t dlen)
1.1 markus 162: {
1.24 dtucker 163: static union {
1.31 markus 164: u_char m[SSH_DIGEST_MAX_LENGTH];
1.24 dtucker 165: u_int64_t for_align;
166: } u;
1.29 markus 167: u_char b[4];
168: u_char nonce[8];
1.1 markus 169:
1.24 dtucker 170: if (mac->mac_len > sizeof(u))
1.31 markus 171: return SSH_ERR_INTERNAL_ERROR;
1.14 pvalchev 172:
173: switch (mac->type) {
1.27 markus 174: case SSH_DIGEST:
1.14 pvalchev 175: put_u32(b, seqno);
176: /* reset HMAC context */
1.27 markus 177: if (ssh_hmac_init(mac->hmac_ctx, NULL, 0) < 0 ||
178: ssh_hmac_update(mac->hmac_ctx, b, sizeof(b)) < 0 ||
179: ssh_hmac_update(mac->hmac_ctx, data, datalen) < 0 ||
180: ssh_hmac_final(mac->hmac_ctx, u.m, sizeof(u.m)) < 0)
1.31 markus 181: return SSH_ERR_LIBCRYPTO_ERROR;
1.14 pvalchev 182: break;
183: case SSH_UMAC:
1.31 markus 184: POKE_U64(nonce, seqno);
1.14 pvalchev 185: umac_update(mac->umac_ctx, data, datalen);
1.24 dtucker 186: umac_final(mac->umac_ctx, u.m, nonce);
1.14 pvalchev 187: break;
1.19 markus 188: case SSH_UMAC128:
189: put_u64(nonce, seqno);
190: umac128_update(mac->umac_ctx, data, datalen);
1.24 dtucker 191: umac128_final(mac->umac_ctx, u.m, nonce);
1.19 markus 192: break;
1.14 pvalchev 193: default:
1.31 markus 194: return SSH_ERR_INVALID_ARGUMENT;
1.14 pvalchev 195: }
1.31 markus 196: if (digest != NULL) {
197: if (dlen > mac->mac_len)
198: dlen = mac->mac_len;
199: memcpy(digest, u.m, dlen);
200: }
1.33 djm 201: return 0;
202: }
203:
204: int
205: mac_check(struct sshmac *mac, u_int32_t seqno,
206: const u_char *data, size_t dlen,
207: const u_char *theirmac, size_t mlen)
208: {
209: u_char ourmac[SSH_DIGEST_MAX_LENGTH];
210: int r;
211:
212: if (mac->mac_len > mlen)
213: return SSH_ERR_INVALID_ARGUMENT;
214: if ((r = mac_compute(mac, seqno, data, dlen,
215: ourmac, sizeof(ourmac))) != 0)
216: return r;
217: if (timingsafe_bcmp(ourmac, theirmac, mac->mac_len) != 0)
218: return SSH_ERR_MAC_INVALID;
1.31 markus 219: return 0;
1.1 markus 220: }
221:
1.13 djm 222: void
1.31 markus 223: mac_clear(struct sshmac *mac)
1.13 djm 224: {
1.14 pvalchev 225: if (mac->type == SSH_UMAC) {
226: if (mac->umac_ctx != NULL)
227: umac_delete(mac->umac_ctx);
1.19 markus 228: } else if (mac->type == SSH_UMAC128) {
229: if (mac->umac_ctx != NULL)
230: umac128_delete(mac->umac_ctx);
1.27 markus 231: } else if (mac->hmac_ctx != NULL)
232: ssh_hmac_free(mac->hmac_ctx);
233: mac->hmac_ctx = NULL;
1.14 pvalchev 234: mac->umac_ctx = NULL;
1.13 djm 235: }
236:
1.1 markus 237: /* XXX copied from ciphers_valid */
238: #define MAC_SEP ","
239: int
240: mac_valid(const char *names)
241: {
242: char *maclist, *cp, *p;
243:
244: if (names == NULL || strcmp(names, "") == 0)
1.31 markus 245: return 0;
246: if ((maclist = cp = strdup(names)) == NULL)
247: return 0;
1.1 markus 248: for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0';
1.3 deraadt 249: (p = strsep(&cp, MAC_SEP))) {
1.13 djm 250: if (mac_setup(NULL, p) < 0) {
1.23 djm 251: free(maclist);
1.31 markus 252: return 0;
1.1 markus 253: }
254: }
1.23 djm 255: free(maclist);
1.31 markus 256: return 1;
1.1 markus 257: }
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