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/*-------------------------------------------------------------------------
*
* passwordcheck.c
*
*
* Copyright (c) 2009-2022, PostgreSQL Global Development Group
*
* Author: Laurenz Albe <laurenz.albe@wien.gv.at>
*
* IDENTIFICATION
* contrib/passwordcheck/passwordcheck.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <ctype.h>
#ifdef USE_CRACKLIB
#include <crack.h>
#endif
#include "commands/user.h"
#include "fmgr.h"
#include "libpq/crypt.h"
PG_MODULE_MAGIC;
/* Saved hook value in case of unload */
static check_password_hook_type prev_check_password_hook = NULL;
/* passwords shorter than this will be rejected */
#define MIN_PWD_LENGTH 8
extern void _PG_init(void);
/*
* check_password
*
* performs checks on an encrypted or unencrypted password
* ereport's if not acceptable
*
* username: name of role being created or changed
* password: new password (possibly already encrypted)
* password_type: PASSWORD_TYPE_* code, to indicate if the password is
* in plaintext or encrypted form.
* validuntil_time: password expiration time, as a timestamptz Datum
* validuntil_null: true if password expiration time is NULL
*
* This sample implementation doesn't pay any attention to the password
* expiration time, but you might wish to insist that it be non-null and
* not too far in the future.
*/
static void
check_password(const char *username,
const char *shadow_pass,
PasswordType password_type,
Datum validuntil_time,
bool validuntil_null)
{
if (prev_check_password_hook)
prev_check_password_hook(username, shadow_pass,
password_type, validuntil_time,
validuntil_null);
if (password_type != PASSWORD_TYPE_PLAINTEXT)
{
/*
* Unfortunately we cannot perform exhaustive checks on encrypted
* passwords - we are restricted to guessing. (Alternatively, we could
* insist on the password being presented non-encrypted, but that has
* its own security disadvantages.)
*
* We only check for username = password.
*/
const char *logdetail = NULL;
if (plain_crypt_verify(username, shadow_pass, username, &logdetail) == STATUS_OK)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("password must not equal user name")));
}
else
{
/*
* For unencrypted passwords we can perform better checks
*/
const char *password = shadow_pass;
int pwdlen = strlen(password);
int i;
bool pwd_has_letter,
pwd_has_nonletter;
#ifdef USE_CRACKLIB
const char *reason;
#endif
/* enforce minimum length */
if (pwdlen < MIN_PWD_LENGTH)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("password is too short")));
/* check if the password contains the username */
if (strstr(password, username))
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("password must not contain user name")));
/* check if the password contains both letters and non-letters */
pwd_has_letter = false;
pwd_has_nonletter = false;
for (i = 0; i < pwdlen; i++)
{
/*
* isalpha() does not work for multibyte encodings but let's
* consider non-ASCII characters non-letters
*/
if (isalpha((unsigned char) password[i]))
pwd_has_letter = true;
else
pwd_has_nonletter = true;
}
if (!pwd_has_letter || !pwd_has_nonletter)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("password must contain both letters and nonletters")));
#ifdef USE_CRACKLIB
/* call cracklib to check password */
if ((reason = FascistCheck(password, CRACKLIB_DICTPATH)))
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("password is easily cracked"),
errdetail_log("cracklib diagnostic: %s", reason)));
#endif
}
/* all checks passed, password is ok */
}
/*
* Module initialization function
*/
void
_PG_init(void)
{
/* activate password checks when the module is loaded */
prev_check_password_hook = check_password_hook;
check_password_hook = check_password;
}
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