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/* vi: set sw=4 ts=4: */
/*
* Mini weak password checker implementation for busybox
*
* Copyright (C) 2006 Tito Ragusa <farmatito@tiscali.it>
*
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/
/* A good password:
1) should contain at least six characters (man passwd);
2) empty passwords are not permitted;
3) should contain a mix of four different types of characters
upper case letters,
lower case letters,
numbers,
special characters such as !@#$%^&*,;".
This password types should not be permitted:
a) pure numbers: birthdates, social security number, license plate, phone numbers;
b) words and all letters only passwords (uppercase, lowercase or mixed)
as palindromes, consecutive or repetitive letters
or adjacent letters on your keyboard;
c) username, real name, company name or (e-mail?) address
in any form (as-is, reversed, capitalized, doubled, etc.).
(we can check only against username, gecos and hostname)
d) common and obvious letter-number replacements
(e.g. replace the letter O with number 0)
such as "M1cr0$0ft" or "P@ssw0rd" (CAVEAT: we cannot check for them
without the use of a dictionary).
For each missing type of characters an increase of password length is
requested.
If user is root we warn only.
CAVEAT: some older versions of crypt() truncates passwords to 8 chars,
so that aaaaaaaa1Q$ is equal to aaaaaaaa making it possible to fool
some of our checks. We don't test for this special case as newer versions
of crypt do not truncate passwords.
*/
#include <ctype.h>
#include <unistd.h>
#include <string.h>
#include <strings.h>
#include "libbb.h"
static int string_checker_helper(const char *p1, const char *p2) __attribute__ ((__pure__));
static int string_checker_helper(const char *p1, const char *p2)
{
/* as-is or capitalized */
if (strcasecmp(p1, p2) == 0
/* as sub-string */
|| strcasestr(p2, p1) != NULL
/* invert in case haystack is shorter than needle */
|| strcasestr(p1, p2) != NULL)
return 1;
return 0;
}
static int string_checker(const char *p1, const char *p2)
{
int size;
/* check string */
int ret = string_checker_helper(p1, p2);
/* Make our own copy */
char *p = bb_xstrdup(p1);
/* reverse string */
size = strlen(p);
while (size--) {
*p = p1[size];
p++;
}
/* restore pointer */
p -= strlen(p1);
/* check reversed string */
ret |= string_checker_helper(p, p2);
/* clean up */
memset(p, 0, strlen(p1));
free(p);
return ret;
}
#define LOWERCASE 1
#define UPPERCASE 2
#define NUMBERS 4
#define SPECIAL 8
static const char *obscure_msg(const char *old_p, const char *new_p, const struct passwd *pw)
{
int i;
int c;
int length;
int mixed = 0;
/* Add 1 for each type of characters to the minlen of password */
int size = CONFIG_PASSWORD_MINLEN + 8;
const char *p;
char hostname[255];
/* size */
if (!new_p || (length = strlen(new_p)) < CONFIG_PASSWORD_MINLEN)
return("too short");
/* no username as-is, as sub-string, reversed, capitalized, doubled */
if (string_checker(new_p, pw->pw_name)) {
return "similar to username";
}
/* no gecos as-is, as sub-string, reversed, capitalized, doubled */
if (string_checker(new_p, pw->pw_gecos)) {
return "similar to gecos";
}
/* hostname as-is, as sub-string, reversed, capitalized, doubled */
if (gethostname(hostname, 255) == 0) {
hostname[254] = '\0';
if (string_checker(new_p, hostname)) {
return "similar to hostname";
}
}
/* Should / Must contain a mix of: */
for (i = 0; i < length; i++) {
if (islower(new_p[i])) { /* a-z */
mixed |= LOWERCASE;
} else if (isupper(new_p[i])) { /* A-Z */
mixed |= UPPERCASE;
} else if (isdigit(new_p[i])) { /* 0-9 */
mixed |= NUMBERS;
} else { /* special characters */
mixed |= SPECIAL;
}
/* More than 50% similar characters ? */
c = 0;
p = new_p;
while (1) {
if ((p = strchr(p, new_p[i])) == NULL) {
break;
}
c++;
if (!++p) {
break; /* move past the matched char if possible */
}
}
if (c >= (length / 2)) {
return "too many similar characters";
}
}
for (i=0; i<4; i++)
if (mixed & (1<<i)) size -= 2;
if (length < size)
return "too weak";
if (old_p && old_p[0] != '\0') {
/* check vs. old password */
if (string_checker(new_p, old_p)) {
return "similar to old password";
}
}
return NULL;
}
int obscure(const char *old, const char *newval, const struct passwd *pwdp)
{
const char *msg;
if ((msg = obscure_msg(old, newval, pwdp))) {
printf("Bad password: %s.\n", msg);
/* If user is root warn only */
return (getuid())? 1 : 0;
}
return 0;
}
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