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1 | /* | |
2 | * Copyright (c) 2001 Markus Friedl. All rights reserved. | |
3 | * | |
4 | * Redistribution and use in source and binary forms, with or without | |
5 | * modification, are permitted provided that the following conditions | |
6 | * are met: | |
7 | * 1. Redistributions of source code must retain the above copyright | |
8 | * notice, this list of conditions and the following disclaimer. | |
9 | * 2. Redistributions in binary form must reproduce the above copyright | |
10 | * notice, this list of conditions and the following disclaimer in the | |
11 | * documentation and/or other materials provided with the distribution. | |
12 | * | |
13 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
14 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
15 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
16 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
17 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
18 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
19 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
20 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
21 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
22 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
23 | */ | |
24 | ||
25 | #include "includes.h" | |
26 | RCSID("$OpenBSD: mac.c,v 1.5 2002/05/16 22:02:50 markus Exp $"); | |
27 | ||
28 | #include <openssl/hmac.h> | |
29 | ||
30 | #include "xmalloc.h" | |
31 | #include "getput.h" | |
32 | #include "log.h" | |
33 | #include "cipher.h" | |
34 | #include "kex.h" | |
35 | #include "mac.h" | |
36 | ||
37 | struct { | |
38 | char *name; | |
39 | const EVP_MD * (*mdfunc)(void); | |
40 | int truncatebits; /* truncate digest if != 0 */ | |
41 | } macs[] = { | |
42 | { "hmac-sha1", EVP_sha1, 0, }, | |
43 | { "hmac-sha1-96", EVP_sha1, 96 }, | |
44 | { "hmac-md5", EVP_md5, 0 }, | |
45 | { "hmac-md5-96", EVP_md5, 96 }, | |
46 | { "hmac-ripemd160", EVP_ripemd160, 0 }, | |
47 | { "hmac-ripemd160@openssh.com", EVP_ripemd160, 0 }, | |
48 | { NULL, NULL, 0 } | |
49 | }; | |
50 | ||
51 | int | |
52 | mac_init(Mac *mac, char *name) | |
53 | { | |
54 | int i; | |
55 | for (i = 0; macs[i].name; i++) { | |
56 | if (strcmp(name, macs[i].name) == 0) { | |
57 | if (mac != NULL) { | |
58 | mac->md = (*macs[i].mdfunc)(); | |
59 | mac->key_len = mac->mac_len = EVP_MD_size(mac->md); | |
60 | if (macs[i].truncatebits != 0) | |
61 | mac->mac_len = macs[i].truncatebits/8; | |
62 | } | |
63 | debug2("mac_init: found %s", name); | |
64 | return (0); | |
65 | } | |
66 | } | |
67 | debug2("mac_init: unknown %s", name); | |
68 | return (-1); | |
69 | } | |
70 | ||
71 | u_char * | |
72 | mac_compute(Mac *mac, u_int32_t seqno, u_char *data, int datalen) | |
73 | { | |
74 | HMAC_CTX c; | |
75 | static u_char m[EVP_MAX_MD_SIZE]; | |
76 | u_char b[4]; | |
77 | ||
78 | if (mac->key == NULL) | |
79 | fatal("mac_compute: no key"); | |
80 | if (mac->mac_len > sizeof(m)) | |
81 | fatal("mac_compute: mac too long"); | |
82 | HMAC_Init(&c, mac->key, mac->key_len, mac->md); | |
83 | PUT_32BIT(b, seqno); | |
84 | HMAC_Update(&c, b, sizeof(b)); | |
85 | HMAC_Update(&c, data, datalen); | |
86 | HMAC_Final(&c, m, NULL); | |
87 | HMAC_cleanup(&c); | |
88 | return (m); | |
89 | } | |
90 | ||
91 | /* XXX copied from ciphers_valid */ | |
92 | #define MAC_SEP "," | |
93 | int | |
94 | mac_valid(const char *names) | |
95 | { | |
96 | char *maclist, *cp, *p; | |
97 | ||
98 | if (names == NULL || strcmp(names, "") == 0) | |
99 | return (0); | |
100 | maclist = cp = xstrdup(names); | |
101 | for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0'; | |
102 | (p = strsep(&cp, MAC_SEP))) { | |
103 | if (mac_init(NULL, p) < 0) { | |
104 | debug("bad mac %s [%s]", p, names); | |
105 | xfree(maclist); | |
106 | return (0); | |
107 | } else { | |
108 | debug3("mac ok: %s [%s]", p, names); | |
109 | } | |
110 | } | |
111 | debug3("macs ok: [%s]", names); | |
112 | xfree(maclist); | |
113 | return (1); | |
114 | } |