Annotation of src/usr.bin/ssh/mac.c, Revision 1.18
1.18 ! dtucker 1: /* $OpenBSD: mac.c,v 1.17 2011/12/02 00:43:57 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:
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) */
46:
1.1 markus 47: struct {
48: char *name;
1.14 pvalchev 49: int type;
1.5 markus 50: const EVP_MD * (*mdfunc)(void);
1.1 markus 51: int truncatebits; /* truncate digest if != 0 */
1.14 pvalchev 52: int key_len; /* just for UMAC */
53: int len; /* just for UMAC */
1.1 markus 54: } macs[] = {
1.14 pvalchev 55: { "hmac-sha1", SSH_EVP, EVP_sha1, 0, -1, -1 },
56: { "hmac-sha1-96", SSH_EVP, EVP_sha1, 96, -1, -1 },
1.16 djm 57: { "hmac-sha2-256", SSH_EVP, EVP_sha256, 0, -1, -1 },
58: { "hmac-sha2-512", SSH_EVP, EVP_sha512, 0, -1, -1 },
1.14 pvalchev 59: { "hmac-md5", SSH_EVP, EVP_md5, 0, -1, -1 },
60: { "hmac-md5-96", SSH_EVP, EVP_md5, 96, -1, -1 },
61: { "hmac-ripemd160", SSH_EVP, EVP_ripemd160, 0, -1, -1 },
62: { "hmac-ripemd160@openssh.com", SSH_EVP, EVP_ripemd160, 0, -1, -1 },
63: { "umac-64@openssh.com", SSH_UMAC, NULL, 0, 128, 64 },
64: { NULL, 0, NULL, 0, -1, -1 }
1.1 markus 65: };
66:
1.14 pvalchev 67: static void
68: mac_setup_by_id(Mac *mac, int which)
69: {
70: int evp_len;
71: mac->type = macs[which].type;
72: if (mac->type == SSH_EVP) {
73: mac->evp_md = (*macs[which].mdfunc)();
74: if ((evp_len = EVP_MD_size(mac->evp_md)) <= 0)
75: fatal("mac %s len %d", mac->name, evp_len);
76: mac->key_len = mac->mac_len = (u_int)evp_len;
77: } else {
78: mac->mac_len = macs[which].len / 8;
79: mac->key_len = macs[which].key_len / 8;
80: mac->umac_ctx = NULL;
81: }
82: if (macs[which].truncatebits != 0)
83: mac->mac_len = macs[which].truncatebits / 8;
84: }
85:
1.1 markus 86: int
1.13 djm 87: mac_setup(Mac *mac, char *name)
1.1 markus 88: {
1.14 pvalchev 89: int i;
1.7 djm 90:
1.1 markus 91: for (i = 0; macs[i].name; i++) {
92: if (strcmp(name, macs[i].name) == 0) {
1.14 pvalchev 93: if (mac != NULL)
94: mac_setup_by_id(mac, i);
1.13 djm 95: debug2("mac_setup: found %s", name);
1.1 markus 96: return (0);
97: }
98: }
1.13 djm 99: debug2("mac_setup: unknown %s", name);
1.1 markus 100: return (-1);
101: }
102:
1.14 pvalchev 103: int
1.13 djm 104: mac_init(Mac *mac)
105: {
106: if (mac->key == NULL)
107: fatal("mac_init: no key");
1.14 pvalchev 108: switch (mac->type) {
109: case SSH_EVP:
110: if (mac->evp_md == NULL)
111: return -1;
1.17 djm 112: HMAC_CTX_init(&mac->evp_ctx);
1.14 pvalchev 113: HMAC_Init(&mac->evp_ctx, mac->key, mac->key_len, mac->evp_md);
114: return 0;
115: case SSH_UMAC:
116: mac->umac_ctx = umac_new(mac->key);
117: return 0;
118: default:
119: return -1;
120: }
1.13 djm 121: }
122:
1.1 markus 123: u_char *
124: mac_compute(Mac *mac, u_int32_t seqno, u_char *data, int datalen)
125: {
126: static u_char m[EVP_MAX_MD_SIZE];
1.14 pvalchev 127: u_char b[4], nonce[8];
1.1 markus 128:
1.7 djm 129: if (mac->mac_len > sizeof(m))
1.14 pvalchev 130: fatal("mac_compute: mac too long %u %lu",
1.15 dtucker 131: mac->mac_len, (u_long)sizeof(m));
1.14 pvalchev 132:
133: switch (mac->type) {
134: case SSH_EVP:
135: put_u32(b, seqno);
136: /* reset HMAC context */
137: HMAC_Init(&mac->evp_ctx, NULL, 0, NULL);
138: HMAC_Update(&mac->evp_ctx, b, sizeof(b));
139: HMAC_Update(&mac->evp_ctx, data, datalen);
140: HMAC_Final(&mac->evp_ctx, m, NULL);
141: break;
142: case SSH_UMAC:
143: put_u64(nonce, seqno);
144: umac_update(mac->umac_ctx, data, datalen);
145: umac_final(mac->umac_ctx, m, nonce);
146: break;
147: default:
148: fatal("mac_compute: unknown MAC type");
149: }
1.1 markus 150: return (m);
151: }
152:
1.13 djm 153: void
154: mac_clear(Mac *mac)
155: {
1.14 pvalchev 156: if (mac->type == SSH_UMAC) {
157: if (mac->umac_ctx != NULL)
158: umac_delete(mac->umac_ctx);
159: } else if (mac->evp_md != NULL)
160: HMAC_cleanup(&mac->evp_ctx);
161: mac->evp_md = NULL;
162: mac->umac_ctx = NULL;
1.13 djm 163: }
164:
1.1 markus 165: /* XXX copied from ciphers_valid */
166: #define MAC_SEP ","
167: int
168: mac_valid(const char *names)
169: {
170: char *maclist, *cp, *p;
171:
172: if (names == NULL || strcmp(names, "") == 0)
173: return (0);
174: maclist = cp = xstrdup(names);
175: for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0';
1.3 deraadt 176: (p = strsep(&cp, MAC_SEP))) {
1.13 djm 177: if (mac_setup(NULL, p) < 0) {
1.1 markus 178: debug("bad mac %s [%s]", p, names);
179: xfree(maclist);
180: return (0);
181: } else {
182: debug3("mac ok: %s [%s]", p, names);
183: }
184: }
185: debug3("macs ok: [%s]", names);
186: xfree(maclist);
187: return (1);
188: }
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