xref: /freebsd/lib/libcrypt/crypt.c (revision 3c4ba5f55438f7afd4f4b0b56f88f2bb505fd6a6)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3  *
4  * Copyright (c) 1999 Mark Murray
5  * Copyright (c) 2014 Dag-Erling Smørgrav
6  * All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  *
17  * THIS SOFTWARE IS PROVIDED BY MARK MURRAY AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL MARK MURRAY OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  */
29 
30 #include <sys/cdefs.h>
31 __FBSDID("$FreeBSD$");
32 
33 #include <sys/types.h>
34 
35 #include <string.h>
36 #include <unistd.h>
37 
38 #include "crypt.h"
39 
40 /*
41  * List of supported crypt(3) formats.
42  *
43  * The default algorithm is the last entry in the list (second-to-last
44  * array element since the last is a sentinel).  The reason for placing
45  * the default last rather than first is that DES needs to be at the
46  * bottom for the algorithm guessing logic in crypt(3) to work correctly,
47  * and it needs to be the default for backward compatibility.
48  */
49 static const struct crypt_format {
50 	const char *name;
51 	int (*func)(const char *, const char *, char *);
52 	const char *magic;
53 } crypt_formats[] = {
54 	{ "md5",	crypt_md5,		"$1$"	},
55 #ifdef HAS_BLOWFISH
56 	{ "blf",	crypt_blowfish,		"$2"	},
57 #endif
58 	{ "nth",	crypt_nthash,		"$3$"	},
59 	{ "sha256",	crypt_sha256,		"$5$"	},
60 	{ "sha512",	crypt_sha512,		"$6$"	},
61 #ifdef HAS_DES
62 	{ "des",	crypt_des,		"_"	},
63 #endif
64 
65 	/* sentinel */
66 	{ NULL,		NULL,			NULL	}
67 };
68 
69 static const struct crypt_format *crypt_format =
70     &crypt_formats[(sizeof crypt_formats / sizeof *crypt_formats) - 2];
71 
72 #define DES_SALT_ALPHABET \
73 	"./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
74 
75 /*
76  * Returns the name of the currently selected format.
77  */
78 const char *
79 crypt_get_format(void)
80 {
81 
82 	return (crypt_format->name);
83 }
84 
85 /*
86  * Selects the format to use for subsequent crypt(3) invocations.
87  */
88 int
89 crypt_set_format(const char *format)
90 {
91 	const struct crypt_format *cf;
92 
93 	for (cf = crypt_formats; cf->name != NULL; ++cf) {
94 		if (strcasecmp(cf->name, format) == 0) {
95 			crypt_format = cf;
96 			return (1);
97 		}
98 	}
99 	return (0);
100 }
101 
102 /*
103  * Hash the given password with the given salt.  If the salt begins with a
104  * magic string (e.g. "$6$" for sha512), the corresponding format is used;
105  * otherwise, the currently selected format is used.
106  */
107 char *
108 crypt_r(const char *passwd, const char *salt, struct crypt_data *data)
109 {
110 	const struct crypt_format *cf;
111 	int (*func)(const char *, const char *, char *);
112 #ifdef HAS_DES
113 	int len;
114 #endif
115 
116 	for (cf = crypt_formats; cf->name != NULL; ++cf)
117 		if (cf->magic != NULL && strstr(salt, cf->magic) == salt) {
118 			func = cf->func;
119 			goto match;
120 		}
121 #ifdef HAS_DES
122 	len = strlen(salt);
123 	if ((len == 13 || len == 2) && strspn(salt, DES_SALT_ALPHABET) == len) {
124 		func = crypt_des;
125 		goto match;
126 	}
127 #endif
128 	func = crypt_format->func;
129 match:
130 	if (func(passwd, salt, data->__buf) != 0)
131 		return (NULL);
132 	return (data->__buf);
133 }
134 
135 char *
136 crypt(const char *passwd, const char *salt)
137 {
138 	static struct crypt_data data;
139 
140 	return (crypt_r(passwd, salt, &data));
141 }
142