[821] | 1 | /* vi: set sw=4 ts=4: */
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| 2 | /*
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| 3 | * Mini weak password checker implementation for busybox
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| 4 | *
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| 5 | * Copyright (C) 2006 Tito Ragusa <farmatito@tiscali.it>
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| 6 | *
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| 7 | * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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| 8 | */
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| 9 |
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| 10 | /* A good password:
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| 11 | 1) should contain at least six characters (man passwd);
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| 12 | 2) empty passwords are not permitted;
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| 13 | 3) should contain a mix of four different types of characters
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| 14 | upper case letters,
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| 15 | lower case letters,
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| 16 | numbers,
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| 17 | special characters such as !@#$%^&*,;".
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| 18 | This password types should not be permitted:
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| 19 | a) pure numbers: birthdates, social security number, license plate, phone numbers;
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| 20 | b) words and all letters only passwords (uppercase, lowercase or mixed)
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| 21 | as palindromes, consecutive or repetitive letters
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| 22 | or adjacent letters on your keyboard;
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| 23 | c) username, real name, company name or (e-mail?) address
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| 24 | in any form (as-is, reversed, capitalized, doubled, etc.).
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| 25 | (we can check only against username, gecos and hostname)
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| 26 | d) common and obvious letter-number replacements
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| 27 | (e.g. replace the letter O with number 0)
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| 28 | such as "M1cr0$0ft" or "P@ssw0rd" (CAVEAT: we cannot check for them
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| 29 | without the use of a dictionary).
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| 30 |
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| 31 | For each missing type of characters an increase of password length is
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| 32 | requested.
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| 33 |
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| 34 | If user is root we warn only.
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| 35 |
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| 36 | CAVEAT: some older versions of crypt() truncates passwords to 8 chars,
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| 37 | so that aaaaaaaa1Q$ is equal to aaaaaaaa making it possible to fool
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| 38 | some of our checks. We don't test for this special case as newer versions
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| 39 | of crypt do not truncate passwords.
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| 40 | */
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| 41 |
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| 42 | #include <ctype.h>
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| 43 | #include <unistd.h>
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| 44 | #include <string.h>
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| 45 | #include <strings.h>
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| 46 |
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| 47 | #include "libbb.h"
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| 48 |
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| 49 |
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| 50 | /* passwords should consist of 6 (to 8 characters) */
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| 51 | #define MINLEN 6
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| 52 |
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| 53 |
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| 54 | static int string_checker_helper(const char *p1, const char *p2) __attribute__ ((__pure__));
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| 55 |
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| 56 | static int string_checker_helper(const char *p1, const char *p2)
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| 57 | {
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| 58 | /* as-is or capitalized */
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| 59 | if (strcasecmp(p1, p2) == 0
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| 60 | /* as sub-string */
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| 61 | || strcasestr(p2, p1) != NULL
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| 62 | /* invert in case haystack is shorter than needle */
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| 63 | || strcasestr(p1, p2) != NULL)
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| 64 | return 1;
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| 65 | return 0;
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| 66 | }
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| 67 |
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| 68 | static int string_checker(const char *p1, const char *p2)
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| 69 | {
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| 70 | int size;
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| 71 | /* check string */
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| 72 | int ret = string_checker_helper(p1, p2);
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| 73 | /* Make our own copy */
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| 74 | char *p = bb_xstrdup(p1);
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| 75 | /* reverse string */
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| 76 | size = strlen(p);
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| 77 |
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| 78 | while (size--) {
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| 79 | *p = p1[size];
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| 80 | p++;
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| 81 | }
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| 82 | /* restore pointer */
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| 83 | p -= strlen(p1);
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| 84 | /* check reversed string */
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| 85 | ret |= string_checker_helper(p, p2);
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| 86 | /* clean up */
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| 87 | memset(p, 0, strlen(p1));
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| 88 | free(p);
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| 89 | return ret;
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| 90 | }
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| 91 |
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| 92 | #define LOWERCASE 1
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| 93 | #define UPPERCASE 2
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| 94 | #define NUMBERS 4
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| 95 | #define SPECIAL 8
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| 96 |
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| 97 | static const char *obscure_msg(const char *old_p, const char *new_p, const struct passwd *pw)
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| 98 | {
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| 99 | int i;
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| 100 | int c;
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| 101 | int length;
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| 102 | int mixed = 0;
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| 103 | /* Add 1 for each type of characters to the minlen of password */
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| 104 | int size = MINLEN + 8;
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| 105 | const char *p;
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| 106 | char hostname[255];
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| 107 |
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| 108 | /* size */
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| 109 | if (!new_p || (length = strlen(new_p)) < MINLEN)
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| 110 | return("too short");
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| 111 |
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| 112 | /* no username as-is, as sub-string, reversed, capitalized, doubled */
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| 113 | if (string_checker(new_p, pw->pw_name)) {
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| 114 | return "similar to username";
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| 115 | }
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| 116 | /* no gecos as-is, as sub-string, reversed, capitalized, doubled */
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| 117 | if (*pw->pw_gecos && string_checker(new_p, pw->pw_gecos)) {
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| 118 | return "similar to gecos";
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| 119 | }
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| 120 | /* hostname as-is, as sub-string, reversed, capitalized, doubled */
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| 121 | if (gethostname(hostname, 255) == 0) {
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| 122 | hostname[254] = '\0';
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| 123 | if (string_checker(new_p, hostname)) {
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| 124 | return "similar to hostname";
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| 125 | }
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| 126 | }
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| 127 |
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| 128 | /* Should / Must contain a mix of: */
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| 129 | for (i = 0; i < length; i++) {
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| 130 | if (islower(new_p[i])) { /* a-z */
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| 131 | mixed |= LOWERCASE;
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| 132 | } else if (isupper(new_p[i])) { /* A-Z */
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| 133 | mixed |= UPPERCASE;
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| 134 | } else if (isdigit(new_p[i])) { /* 0-9 */
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| 135 | mixed |= NUMBERS;
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| 136 | } else { /* special characters */
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| 137 | mixed |= SPECIAL;
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| 138 | }
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| 139 | /* More than 50% similar characters ? */
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| 140 | c = 0;
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| 141 | p = new_p;
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| 142 | while (1) {
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| 143 | if ((p = strchr(p, new_p[i])) == NULL) {
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| 144 | break;
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| 145 | }
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| 146 | c++;
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| 147 | if (!++p) {
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| 148 | break; /* move past the matched char if possible */
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| 149 | }
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| 150 | }
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| 151 |
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| 152 | if (c >= (length / 2)) {
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| 153 | return "too many similar characters";
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| 154 | }
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| 155 | }
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| 156 | for (i=0; i<4; i++)
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| 157 | if (mixed & (1<<i)) size -= 2;
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| 158 | if (length < size)
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| 159 | return "too weak";
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| 160 |
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| 161 | if (old_p && old_p[0] != '\0') {
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| 162 | /* check vs. old password */
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| 163 | if (string_checker(new_p, old_p)) {
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| 164 | return "similar to old password";
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| 165 | }
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| 166 | }
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| 167 | return NULL;
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| 168 | }
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| 169 |
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| 170 | int obscure(const char *old, const char *newval, const struct passwd *pwdp)
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| 171 | {
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| 172 | const char *msg;
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| 173 |
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| 174 | if ((msg = obscure_msg(old, newval, pwdp))) {
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| 175 | printf("Bad password: %s.\n", msg);
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| 176 | /* If user is root warn only */
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| 177 | return (getuid())? 1 : 0;
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| 178 | }
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| 179 | return 0;
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| 180 | }
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