Annotation of src/usr.bin/ssh/mac.c, Revision 1.21
1.21 ! sthen 1: /* $OpenBSD: mac.c,v 1.20 2012/12/11 22:31:18 markus 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:
1.1 markus 48: struct {
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 */
1.1 markus 56: } macs[] = {
1.20 markus 57: /* Encrypt-and-MAC (encrypt-and-authenticate) variants */
58: { "hmac-sha1", SSH_EVP, EVP_sha1, 0, 0, 0, 0 },
59: { "hmac-sha1-96", SSH_EVP, EVP_sha1, 96, 0, 0, 0 },
60: { "hmac-sha2-256", SSH_EVP, EVP_sha256, 0, 0, 0, 0 },
61: { "hmac-sha2-512", SSH_EVP, EVP_sha512, 0, 0, 0, 0 },
62: { "hmac-md5", SSH_EVP, EVP_md5, 0, 0, 0, 0 },
63: { "hmac-md5-96", SSH_EVP, EVP_md5, 96, 0, 0, 0 },
64: { "hmac-ripemd160", SSH_EVP, EVP_ripemd160, 0, 0, 0, 0 },
65: { "hmac-ripemd160@openssh.com", SSH_EVP, EVP_ripemd160, 0, 0, 0, 0 },
66: { "umac-64@openssh.com", SSH_UMAC, NULL, 0, 128, 64, 0 },
67: { "umac-128@openssh.com", SSH_UMAC128, NULL, 0, 128, 128, 0 },
68:
69: /* Encrypt-then-MAC variants */
70: { "hmac-sha1-etm@openssh.com", SSH_EVP, EVP_sha1, 0, 0, 0, 1 },
71: { "hmac-sha1-96-etm@openssh.com", SSH_EVP, EVP_sha1, 96, 0, 0, 1 },
72: { "hmac-sha2-256-etm@openssh.com", SSH_EVP, EVP_sha256, 0, 0, 0, 1 },
73: { "hmac-sha2-512-etm@openssh.com", SSH_EVP, EVP_sha512, 0, 0, 0, 1 },
74: { "hmac-md5-etm@openssh.com", SSH_EVP, EVP_md5, 0, 0, 0, 1 },
75: { "hmac-md5-96-etm@openssh.com", SSH_EVP, EVP_md5, 96, 0, 0, 1 },
1.21 ! sthen 76: { "hmac-ripemd160-etm@openssh.com", SSH_EVP, EVP_ripemd160, 0, 0, 0, 1 },
1.20 markus 77: { "umac-64-etm@openssh.com", SSH_UMAC, NULL, 0, 128, 64, 1 },
78: { "umac-128-etm@openssh.com", SSH_UMAC128, NULL, 0, 128, 128, 1 },
79:
80: { NULL, 0, NULL, 0, 0, 0, 0 }
1.1 markus 81: };
82:
1.14 pvalchev 83: static void
84: mac_setup_by_id(Mac *mac, int which)
85: {
86: int evp_len;
87: mac->type = macs[which].type;
88: if (mac->type == SSH_EVP) {
89: mac->evp_md = (*macs[which].mdfunc)();
90: if ((evp_len = EVP_MD_size(mac->evp_md)) <= 0)
91: fatal("mac %s len %d", mac->name, evp_len);
92: mac->key_len = mac->mac_len = (u_int)evp_len;
93: } else {
94: mac->mac_len = macs[which].len / 8;
95: mac->key_len = macs[which].key_len / 8;
96: mac->umac_ctx = NULL;
97: }
98: if (macs[which].truncatebits != 0)
99: mac->mac_len = macs[which].truncatebits / 8;
1.20 markus 100: mac->etm = macs[which].etm;
1.14 pvalchev 101: }
102:
1.1 markus 103: int
1.13 djm 104: mac_setup(Mac *mac, char *name)
1.1 markus 105: {
1.14 pvalchev 106: int i;
1.7 djm 107:
1.1 markus 108: for (i = 0; macs[i].name; i++) {
109: if (strcmp(name, macs[i].name) == 0) {
1.14 pvalchev 110: if (mac != NULL)
111: mac_setup_by_id(mac, i);
1.13 djm 112: debug2("mac_setup: found %s", name);
1.1 markus 113: return (0);
114: }
115: }
1.13 djm 116: debug2("mac_setup: unknown %s", name);
1.1 markus 117: return (-1);
118: }
119:
1.14 pvalchev 120: int
1.13 djm 121: mac_init(Mac *mac)
122: {
123: if (mac->key == NULL)
124: fatal("mac_init: no key");
1.14 pvalchev 125: switch (mac->type) {
126: case SSH_EVP:
127: if (mac->evp_md == NULL)
128: return -1;
1.17 djm 129: HMAC_CTX_init(&mac->evp_ctx);
1.14 pvalchev 130: HMAC_Init(&mac->evp_ctx, mac->key, mac->key_len, mac->evp_md);
131: return 0;
132: case SSH_UMAC:
133: mac->umac_ctx = umac_new(mac->key);
134: return 0;
1.19 markus 135: case SSH_UMAC128:
136: mac->umac_ctx = umac128_new(mac->key);
137: return 0;
1.14 pvalchev 138: default:
139: return -1;
140: }
1.13 djm 141: }
142:
1.1 markus 143: u_char *
144: mac_compute(Mac *mac, u_int32_t seqno, u_char *data, int datalen)
145: {
146: static u_char m[EVP_MAX_MD_SIZE];
1.14 pvalchev 147: u_char b[4], nonce[8];
1.1 markus 148:
1.7 djm 149: if (mac->mac_len > sizeof(m))
1.14 pvalchev 150: fatal("mac_compute: mac too long %u %lu",
1.15 dtucker 151: mac->mac_len, (u_long)sizeof(m));
1.14 pvalchev 152:
153: switch (mac->type) {
154: case SSH_EVP:
155: put_u32(b, seqno);
156: /* reset HMAC context */
157: HMAC_Init(&mac->evp_ctx, NULL, 0, NULL);
158: HMAC_Update(&mac->evp_ctx, b, sizeof(b));
159: HMAC_Update(&mac->evp_ctx, data, datalen);
160: HMAC_Final(&mac->evp_ctx, m, NULL);
161: break;
162: case SSH_UMAC:
163: put_u64(nonce, seqno);
164: umac_update(mac->umac_ctx, data, datalen);
165: umac_final(mac->umac_ctx, m, nonce);
166: break;
1.19 markus 167: case SSH_UMAC128:
168: put_u64(nonce, seqno);
169: umac128_update(mac->umac_ctx, data, datalen);
170: umac128_final(mac->umac_ctx, m, nonce);
171: break;
1.14 pvalchev 172: default:
173: fatal("mac_compute: unknown MAC type");
174: }
1.1 markus 175: return (m);
176: }
177:
1.13 djm 178: void
179: mac_clear(Mac *mac)
180: {
1.14 pvalchev 181: if (mac->type == SSH_UMAC) {
182: if (mac->umac_ctx != NULL)
183: umac_delete(mac->umac_ctx);
1.19 markus 184: } else if (mac->type == SSH_UMAC128) {
185: if (mac->umac_ctx != NULL)
186: umac128_delete(mac->umac_ctx);
1.14 pvalchev 187: } else if (mac->evp_md != NULL)
188: HMAC_cleanup(&mac->evp_ctx);
189: mac->evp_md = NULL;
190: mac->umac_ctx = NULL;
1.13 djm 191: }
192:
1.1 markus 193: /* XXX copied from ciphers_valid */
194: #define MAC_SEP ","
195: int
196: mac_valid(const char *names)
197: {
198: char *maclist, *cp, *p;
199:
200: if (names == NULL || strcmp(names, "") == 0)
201: return (0);
202: maclist = cp = xstrdup(names);
203: for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0';
1.3 deraadt 204: (p = strsep(&cp, MAC_SEP))) {
1.13 djm 205: if (mac_setup(NULL, p) < 0) {
1.1 markus 206: debug("bad mac %s [%s]", p, names);
207: xfree(maclist);
208: return (0);
209: } else {
210: debug3("mac ok: %s [%s]", p, names);
211: }
212: }
213: debug3("macs ok: [%s]", names);
214: xfree(maclist);
215: return (1);
216: }
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