2 * The general entry points for password strength checking.
4 * Provides the strength_init, strength_check, and strength_close entry points
5 * for doing password strength checking. These are the only interfaces that
6 * are called by the implementation-specific code, and all other checks are
7 * wrapped up in those interfaces.
9 * Developed by Derrick Brashear and Ken Hornstein of Sine Nomine Associates,
10 * on behalf of Stanford University
11 * Extensive modifications by Russ Allbery <eagle@eyrie.org>
12 * Copyright 2006, 2007, 2009, 2012, 2013, 2014
13 * The Board of Trustees of the Leland Stanford Junior University
15 * See LICENSE for licensing terms.
19 #include <portable/krb5.h>
20 #include <portable/system.h>
24 #include <plugin/internal.h>
25 #include <util/macros.h>
29 * Initialize the module. Ensure that the dictionary file exists and is
30 * readable and store the path in the module context. Returns 0 on success,
31 * non-zero on failure. This function returns failure only if it could not
32 * allocate memory or internal Kerberos calls that shouldn't fail do.
34 * The dictionary file should not include the trailing .pwd extension.
35 * Currently, we don't cope with a NULL dictionary path.
38 strength_init(krb5_context ctx, const char *dictionary,
39 krb5_pwqual_moddata *moddata)
41 krb5_pwqual_moddata data = NULL;
44 /* Allocate our internal data. */
45 data = calloc(1, sizeof(*data));
47 return strength_error_system(ctx, "cannot allocate memory");
50 /* Get minimum length and character information from krb5.conf. */
51 strength_config_number(ctx, "minimum_different", &data->minimum_different);
52 strength_config_number(ctx, "minimum_length", &data->minimum_length);
54 /* Get simple character class restrictions from krb5.conf. */
55 strength_config_boolean(ctx, "require_ascii_printable", &data->ascii);
56 strength_config_boolean(ctx, "require_non_letter", &data->nonletter);
58 /* Get complex character class restrictions from krb5.conf. */
59 code = strength_config_classes(ctx, "require_classes", &data->rules);
63 /* Get CrackLib maximum length from krb5.conf. */
64 strength_config_number(ctx, "cracklib_maxlen", &data->cracklib_maxlen);
67 * Try to initialize CDB, CrackLib, and SQLite dictionaries. These
68 * functions handle their own configuration parsing and will do nothing if
69 * the corresponding dictionary is not configured.
71 code = strength_init_cracklib(ctx, data, dictionary);
74 code = strength_init_cdb(ctx, data);
77 code = strength_init_sqlite(ctx, data);
81 /* Initialized. Set moddata and return. */
87 strength_close(ctx, data);
94 * Check if a password contains only printable ASCII characters.
97 only_printable_ascii(const char *password)
101 for (p = password; *p != '\0'; p++)
102 if (!isascii((unsigned char) *p) || !isprint((unsigned char) *p))
109 * Check if a password contains only letters and spaces.
112 only_alpha_space(const char *password)
116 for (p = password; *p != '\0'; p++)
117 if (!isalpha((unsigned char) *p) && *p != ' ')
124 * Check if a password has a sufficient number of unique characters. Takes
125 * the password and the required number of characters.
128 has_minimum_different(const char *password, long minimum)
133 /* Special cases for passwords of length 0 and a minimum <= 1. */
134 if (password == NULL || password[0] == '\0')
140 * Count the number of unique characters by incrementing the count if each
141 * subsequent character is not found in the previous password characters.
142 * This algorithm is O(n^2), but passwords are short enough it shouldn't
146 for (p = password + 1; *p != '\0'; p++)
147 if (memchr(password, *p, p - password) == NULL) {
149 if (unique >= (size_t) minimum)
157 * Check a given password. Takes a Kerberos context, our module data, the
158 * password, the principal the password is for, and a buffer and buffer length
159 * into which to put any failure message.
162 strength_check(krb5_context ctx UNUSED, krb5_pwqual_moddata data,
163 const char *principal, const char *password)
165 krb5_error_code code;
167 /* Check minimum length first, since that's easy. */
168 if ((long) strlen(password) < data->minimum_length)
169 return strength_error_tooshort(ctx, ERROR_SHORT);
172 * If desired, check whether the password contains non-ASCII or
173 * non-printable ASCII characters.
175 if (data->ascii && !only_printable_ascii(password))
176 return strength_error_generic(ctx, ERROR_ASCII);
179 * If desired, ensure the password has a non-letter (and non-space)
180 * character. This requires that people using phrases at least include a
181 * digit or punctuation to make phrase dictionary attacks or dictionary
182 * attacks via combinations of words harder.
184 if (data->nonletter && only_alpha_space(password))
185 return strength_error_class(ctx, ERROR_LETTER);
187 /* If desired, check for enough unique characters. */
188 if (data->minimum_different > 0)
189 if (!has_minimum_different(password, data->minimum_different))
190 return strength_error_class(ctx, ERROR_MINDIFF);
193 * If desired, check that the password satisfies character class
196 code = strength_check_classes(ctx, data, password);
200 /* Check if the password is based on the principal in some way. */
201 code = strength_check_principal(ctx, data, principal, password);
205 /* Check the password against CDB, CrackLib, and SQLite if configured. */
206 code = strength_check_cracklib(ctx, data, password);
209 code = strength_check_cdb(ctx, data, password);
212 code = strength_check_sqlite(ctx, data, password);
216 /* Success. Password accepted. */
222 * Cleanly shut down the password strength plugin. The only thing we have to
223 * do is free the memory allocated for our internal data.
226 strength_close(krb5_context ctx UNUSED, krb5_pwqual_moddata data)
228 struct class_rule *last, *tmp;
232 strength_close_cdb(ctx, data);
233 strength_close_sqlite(ctx, data);
235 while (last != NULL) {
240 free(data->dictionary);