xref: /freebsd/lib/libcrypt/crypt.c (revision 315ee00f)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
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 #include <sys/types.h>
32 
33 #include <string.h>
34 #include <unistd.h>
35 
36 #include "crypt.h"
37 
38 /*
39  * List of supported crypt(3) formats.
40  *
41  * The default algorithm is the last entry in the list (second-to-last
42  * array element since the last is a sentinel).  The reason for placing
43  * the default last rather than first is that DES needs to be at the
44  * bottom for the algorithm guessing logic in crypt(3) to work correctly,
45  * and it needs to be the default for backward compatibility.
46  */
47 static const struct crypt_format {
48 	const char *name;
49 	int (*func)(const char *, const char *, char *);
50 	const char *magic;
51 } crypt_formats[] = {
52 	{ "md5",	crypt_md5,		"$1$"	},
53 #ifdef HAS_BLOWFISH
54 	{ "blf",	crypt_blowfish,		"$2"	},
55 #endif
56 	{ "nth",	crypt_nthash,		"$3$"	},
57 	{ "sha256",	crypt_sha256,		"$5$"	},
58 	{ "sha512",	crypt_sha512,		"$6$"	},
59 #ifdef HAS_DES
60 	{ "des",	crypt_des,		"_"	},
61 #endif
62 
63 	/* sentinel */
64 	{ NULL,		NULL,			NULL	}
65 };
66 
67 static const struct crypt_format *crypt_format =
68     &crypt_formats[(sizeof crypt_formats / sizeof *crypt_formats) - 2];
69 
70 #define DES_SALT_ALPHABET \
71 	"./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
72 
73 /*
74  * Returns the name of the currently selected format.
75  */
76 const char *
77 crypt_get_format(void)
78 {
79 
80 	return (crypt_format->name);
81 }
82 
83 /*
84  * Selects the format to use for subsequent crypt(3) invocations.
85  */
86 int
87 crypt_set_format(const char *format)
88 {
89 	const struct crypt_format *cf;
90 
91 	for (cf = crypt_formats; cf->name != NULL; ++cf) {
92 		if (strcasecmp(cf->name, format) == 0) {
93 			crypt_format = cf;
94 			return (1);
95 		}
96 	}
97 	return (0);
98 }
99 
100 /*
101  * Hash the given password with the given salt.  If the salt begins with a
102  * magic string (e.g. "$6$" for sha512), the corresponding format is used;
103  * otherwise, the currently selected format is used.
104  */
105 char *
106 crypt_r(const char *passwd, const char *salt, struct crypt_data *data)
107 {
108 	const struct crypt_format *cf;
109 	int (*func)(const char *, const char *, char *);
110 #ifdef HAS_DES
111 	int len;
112 #endif
113 
114 	for (cf = crypt_formats; cf->name != NULL; ++cf)
115 		if (cf->magic != NULL && strstr(salt, cf->magic) == salt) {
116 			func = cf->func;
117 			goto match;
118 		}
119 #ifdef HAS_DES
120 	len = strlen(salt);
121 	if ((len == 13 || len == 2) && strspn(salt, DES_SALT_ALPHABET) == len) {
122 		func = crypt_des;
123 		goto match;
124 	}
125 #endif
126 	func = crypt_format->func;
127 match:
128 	if (func(passwd, salt, data->__buf) != 0)
129 		return (NULL);
130 	return (data->__buf);
131 }
132 
133 char *
134 crypt(const char *passwd, const char *salt)
135 {
136 	static struct crypt_data data;
137 
138 	return (crypt_r(passwd, salt, &data));
139 }
140