1 files changed, 170 insertions, 0 deletions

diff --git a/libbb/obscure.c b/libbb/obscure.c
new file mode 100644
index 000000000..2599095df
--- /dev/null
+++ b/libbb/obscure.c
@@ -0,0 +1,170 @@
+/* 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 "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 = 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 2 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 (*pw->pw_gecos && 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 *pw)
+{
+        const char *msg;
+
+        msg = obscure_msg(old, newval, pw);
+        if (msg) {
+                printf("Bad password: %s\n", msg);
+                return 1;
+        }
+        return 0;
+}