Annotation of src/usr.bin/ssh/mac.c, Revision 1.35
1.35 ! djm 1: /* $OpenBSD: mac.c,v 1.34 2017/05/08 22:57:38 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>
1.35 ! djm 30: #include <stdlib.h>
1.1 markus 31:
1.27 markus 32: #include "digest.h"
33: #include "hmac.h"
1.14 pvalchev 34: #include "umac.h"
1.31 markus 35: #include "mac.h"
36: #include "misc.h"
37: #include "ssherr.h"
38: #include "sshbuf.h"
1.14 pvalchev 39:
1.27 markus 40: #define SSH_DIGEST 1 /* SSH_DIGEST_XXX */
1.14 pvalchev 41: #define SSH_UMAC 2 /* UMAC (not integrated with OpenSSL) */
1.19 markus 42: #define SSH_UMAC128 3
1.14 pvalchev 43:
1.22 djm 44: struct macalg {
1.1 markus 45: char *name;
1.14 pvalchev 46: int type;
1.27 markus 47: int alg;
1.1 markus 48: int truncatebits; /* truncate digest if != 0 */
1.14 pvalchev 49: int key_len; /* just for UMAC */
50: int len; /* just for UMAC */
1.20 markus 51: int etm; /* Encrypt-then-MAC */
1.22 djm 52: };
53:
54: static const struct macalg macs[] = {
1.20 markus 55: /* Encrypt-and-MAC (encrypt-and-authenticate) variants */
1.27 markus 56: { "hmac-sha1", SSH_DIGEST, SSH_DIGEST_SHA1, 0, 0, 0, 0 },
57: { "hmac-sha1-96", SSH_DIGEST, SSH_DIGEST_SHA1, 96, 0, 0, 0 },
58: { "hmac-sha2-256", SSH_DIGEST, SSH_DIGEST_SHA256, 0, 0, 0, 0 },
59: { "hmac-sha2-512", SSH_DIGEST, SSH_DIGEST_SHA512, 0, 0, 0, 0 },
60: { "hmac-md5", SSH_DIGEST, SSH_DIGEST_MD5, 0, 0, 0, 0 },
61: { "hmac-md5-96", SSH_DIGEST, SSH_DIGEST_MD5, 96, 0, 0, 0 },
62: { "umac-64@openssh.com", SSH_UMAC, 0, 0, 128, 64, 0 },
63: { "umac-128@openssh.com", SSH_UMAC128, 0, 0, 128, 128, 0 },
1.20 markus 64:
65: /* Encrypt-then-MAC variants */
1.27 markus 66: { "hmac-sha1-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA1, 0, 0, 0, 1 },
67: { "hmac-sha1-96-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA1, 96, 0, 0, 1 },
68: { "hmac-sha2-256-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA256, 0, 0, 0, 1 },
69: { "hmac-sha2-512-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA512, 0, 0, 0, 1 },
70: { "hmac-md5-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_MD5, 0, 0, 0, 1 },
71: { "hmac-md5-96-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_MD5, 96, 0, 0, 1 },
72: { "umac-64-etm@openssh.com", SSH_UMAC, 0, 0, 128, 64, 1 },
73: { "umac-128-etm@openssh.com", SSH_UMAC128, 0, 0, 128, 128, 1 },
1.20 markus 74:
1.27 markus 75: { NULL, 0, 0, 0, 0, 0, 0 }
1.1 markus 76: };
77:
1.25 dtucker 78: /* Returns a list of supported MACs separated by the specified char. */
1.22 djm 79: char *
1.25 dtucker 80: mac_alg_list(char sep)
1.22 djm 81: {
1.31 markus 82: char *ret = NULL, *tmp;
1.22 djm 83: size_t nlen, rlen = 0;
84: const struct macalg *m;
85:
86: for (m = macs; m->name != NULL; m++) {
87: if (ret != NULL)
1.25 dtucker 88: ret[rlen++] = sep;
1.22 djm 89: nlen = strlen(m->name);
1.31 markus 90: if ((tmp = realloc(ret, rlen + nlen + 2)) == NULL) {
91: free(ret);
92: return NULL;
93: }
94: ret = tmp;
1.22 djm 95: memcpy(ret + rlen, m->name, nlen + 1);
96: rlen += nlen;
97: }
98: return ret;
99: }
100:
1.31 markus 101: static int
102: mac_setup_by_alg(struct sshmac *mac, const struct macalg *macalg)
1.14 pvalchev 103: {
1.22 djm 104: mac->type = macalg->type;
1.27 markus 105: if (mac->type == SSH_DIGEST) {
106: if ((mac->hmac_ctx = ssh_hmac_start(macalg->alg)) == NULL)
1.31 markus 107: return SSH_ERR_ALLOC_FAIL;
1.27 markus 108: mac->key_len = mac->mac_len = ssh_hmac_bytes(macalg->alg);
1.14 pvalchev 109: } else {
1.22 djm 110: mac->mac_len = macalg->len / 8;
111: mac->key_len = macalg->key_len / 8;
1.14 pvalchev 112: mac->umac_ctx = NULL;
113: }
1.22 djm 114: if (macalg->truncatebits != 0)
115: mac->mac_len = macalg->truncatebits / 8;
116: mac->etm = macalg->etm;
1.31 markus 117: return 0;
1.14 pvalchev 118: }
119:
1.1 markus 120: int
1.31 markus 121: mac_setup(struct sshmac *mac, char *name)
1.1 markus 122: {
1.22 djm 123: const struct macalg *m;
1.7 djm 124:
1.22 djm 125: for (m = macs; m->name != NULL; m++) {
126: if (strcmp(name, m->name) != 0)
127: continue;
1.31 markus 128: if (mac != NULL)
129: return mac_setup_by_alg(mac, m);
130: return 0;
1.1 markus 131: }
1.31 markus 132: return SSH_ERR_INVALID_ARGUMENT;
1.1 markus 133: }
134:
1.14 pvalchev 135: int
1.31 markus 136: mac_init(struct sshmac *mac)
1.13 djm 137: {
138: if (mac->key == NULL)
1.31 markus 139: return SSH_ERR_INVALID_ARGUMENT;
1.14 pvalchev 140: switch (mac->type) {
1.27 markus 141: case SSH_DIGEST:
142: if (mac->hmac_ctx == NULL ||
143: ssh_hmac_init(mac->hmac_ctx, mac->key, mac->key_len) < 0)
1.31 markus 144: return SSH_ERR_INVALID_ARGUMENT;
1.14 pvalchev 145: return 0;
146: case SSH_UMAC:
1.31 markus 147: if ((mac->umac_ctx = umac_new(mac->key)) == NULL)
148: return SSH_ERR_ALLOC_FAIL;
1.14 pvalchev 149: return 0;
1.19 markus 150: case SSH_UMAC128:
1.32 naddy 151: if ((mac->umac_ctx = umac128_new(mac->key)) == NULL)
152: return SSH_ERR_ALLOC_FAIL;
1.19 markus 153: return 0;
1.14 pvalchev 154: default:
1.31 markus 155: return SSH_ERR_INVALID_ARGUMENT;
1.14 pvalchev 156: }
1.13 djm 157: }
158:
1.31 markus 159: int
1.33 djm 160: mac_compute(struct sshmac *mac, u_int32_t seqno,
161: const u_char *data, int datalen,
1.31 markus 162: u_char *digest, size_t dlen)
1.1 markus 163: {
1.24 dtucker 164: static union {
1.31 markus 165: u_char m[SSH_DIGEST_MAX_LENGTH];
1.24 dtucker 166: u_int64_t for_align;
167: } u;
1.29 markus 168: u_char b[4];
169: u_char nonce[8];
1.1 markus 170:
1.24 dtucker 171: if (mac->mac_len > sizeof(u))
1.31 markus 172: return SSH_ERR_INTERNAL_ERROR;
1.14 pvalchev 173:
174: switch (mac->type) {
1.27 markus 175: case SSH_DIGEST:
1.14 pvalchev 176: put_u32(b, seqno);
177: /* reset HMAC context */
1.27 markus 178: if (ssh_hmac_init(mac->hmac_ctx, NULL, 0) < 0 ||
179: ssh_hmac_update(mac->hmac_ctx, b, sizeof(b)) < 0 ||
180: ssh_hmac_update(mac->hmac_ctx, data, datalen) < 0 ||
181: ssh_hmac_final(mac->hmac_ctx, u.m, sizeof(u.m)) < 0)
1.31 markus 182: return SSH_ERR_LIBCRYPTO_ERROR;
1.14 pvalchev 183: break;
184: case SSH_UMAC:
1.31 markus 185: POKE_U64(nonce, seqno);
1.14 pvalchev 186: umac_update(mac->umac_ctx, data, datalen);
1.24 dtucker 187: umac_final(mac->umac_ctx, u.m, nonce);
1.14 pvalchev 188: break;
1.19 markus 189: case SSH_UMAC128:
190: put_u64(nonce, seqno);
191: umac128_update(mac->umac_ctx, data, datalen);
1.24 dtucker 192: umac128_final(mac->umac_ctx, u.m, nonce);
1.19 markus 193: break;
1.14 pvalchev 194: default:
1.31 markus 195: return SSH_ERR_INVALID_ARGUMENT;
1.14 pvalchev 196: }
1.31 markus 197: if (digest != NULL) {
198: if (dlen > mac->mac_len)
199: dlen = mac->mac_len;
200: memcpy(digest, u.m, dlen);
201: }
1.33 djm 202: return 0;
203: }
204:
205: int
206: mac_check(struct sshmac *mac, u_int32_t seqno,
207: const u_char *data, size_t dlen,
208: const u_char *theirmac, size_t mlen)
209: {
210: u_char ourmac[SSH_DIGEST_MAX_LENGTH];
211: int r;
212:
213: if (mac->mac_len > mlen)
214: return SSH_ERR_INVALID_ARGUMENT;
215: if ((r = mac_compute(mac, seqno, data, dlen,
216: ourmac, sizeof(ourmac))) != 0)
217: return r;
218: if (timingsafe_bcmp(ourmac, theirmac, mac->mac_len) != 0)
219: return SSH_ERR_MAC_INVALID;
1.31 markus 220: return 0;
1.1 markus 221: }
222:
1.13 djm 223: void
1.31 markus 224: mac_clear(struct sshmac *mac)
1.13 djm 225: {
1.14 pvalchev 226: if (mac->type == SSH_UMAC) {
227: if (mac->umac_ctx != NULL)
228: umac_delete(mac->umac_ctx);
1.19 markus 229: } else if (mac->type == SSH_UMAC128) {
230: if (mac->umac_ctx != NULL)
231: umac128_delete(mac->umac_ctx);
1.27 markus 232: } else if (mac->hmac_ctx != NULL)
233: ssh_hmac_free(mac->hmac_ctx);
234: mac->hmac_ctx = NULL;
1.14 pvalchev 235: mac->umac_ctx = NULL;
1.13 djm 236: }
237:
1.1 markus 238: /* XXX copied from ciphers_valid */
239: #define MAC_SEP ","
240: int
241: mac_valid(const char *names)
242: {
243: char *maclist, *cp, *p;
244:
245: if (names == NULL || strcmp(names, "") == 0)
1.31 markus 246: return 0;
247: if ((maclist = cp = strdup(names)) == NULL)
248: return 0;
1.1 markus 249: for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0';
1.3 deraadt 250: (p = strsep(&cp, MAC_SEP))) {
1.13 djm 251: if (mac_setup(NULL, p) < 0) {
1.23 djm 252: free(maclist);
1.31 markus 253: return 0;
1.1 markus 254: }
255: }
1.23 djm 256: free(maclist);
1.31 markus 257: return 1;
1.1 markus 258: }
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