ppm.c - OpenLDAP password policy module

version 1.6

ppm.c is an OpenLDAP module for checking password quality when they are modified. Passwords are checked against the presence or absence of certain character classes.

This module is used as an extension of the OpenLDAP password policy controls, see slapo-ppolicy(5) section pwdCheckModule.

contributions

• 2014 - 2017 - David Coutadeur [email protected] - maintainer
• 2015 - Daly Chikhaoui - Janua [email protected] - contribution on RDN checks
• 2017 - tdb - Tim Bishop - contribution on some compilation improvements

INSTALLATION

See INSTALL file

USAGE

See INSTALL file

Password checks

• 4 character classes are defined by default: upper case, lower case, digits and special characters.

• more character classes can be defined, just write your own.

• passwords must match the amount of quality points. A point is validated when at least m characters of the corresponding character class are present in the password.

• passwords must have at least n of the corresponding character class present, else they are rejected.

• the two previous criterias are checked against any specific character class defined.

• if a password contains any of the forbidden characters, then it is rejected.

• if a password contains tokens from the RDN, then it is rejected.

• if a password is too long, it can be rejected.

• if a password does not pass cracklib check, it can be rejected.

Configuration file

The configuration file (/etc/openldap/ppm.conf by default) contains parameters for the module. The PPM_CONFIG_FILE environment variable, if defined, overloads the configuration file path. If the file is not found, parameters are given their default value.

The syntax of the file is : parameter value [min] [minForPoint]

with spaces being delimiters. Parameter names ARE case sensitive

The default configuration file is the following:

# minQuality parameter
# Format:
# minQuality [NUMBER]
# Description:
# One point is granted for each class for which MIN_FOR_POINT criteria is fulfilled.
# defines the minimum point numbers for the password to be accepted.
minQuality 3

# maxLength parameter
# Format:
# maxLength [NUMBER]
# Description:
# The password must not be more than [NUMBER] long. 0 means no limit is set.
maxLength 0

# checkRDN parameter
# Format:
# checkRDN [0 | 1]
# Description:
# If set to 1, password must not contain a token from the RDN.
# Tokens are separated by the following delimiters : space tabulation _ - , ; £
checkRDN 0

# forbiddenChars parameter
# Format:
# forbiddenChars [CHARACTERS_FORBIDDEN]
# Description:
# Defines the forbidden characters list (no separator).
# If one of them is found in the password, then it is rejected.
forbiddenChars

# maxConsecutivePerClass parameter
# Format:
# maxConsecutivePerClass [NUMBER]
# Description:
# Defines the maximum number of consecutive character allowed for any class
maxConsecutivePerClass 0

# useCracklib parameter
# Format:
# useCracklib [0 | 1]
# Description:
# If set to 1, the password must pass the cracklib check
useCracklib 0

# cracklibDict parameter
# Format:
# cracklibDict [path_to_cracklib_dictionnary]
# Description:
# directory+filename-prefix that your version of CrackLib will go hunting for
# For example, /var/pw_dict resolves as /var/pw_dict.pwd,
# /var/pw_dict.pwi and /var/pw_dict.hwm dictionnary files
cracklibDict /var/cache/cracklib/cracklib_dict

# classes parameter
# Format:
# class-[CLASS_NAME] [CHARACTERS_DEFINING_CLASS] [MIN] [MIN_FOR_POINT]
# Description:
# [CHARACTERS_DEFINING_CLASS]: characters defining the class (no separator)
# [MIN]: If at least [MIN] characters of this class is not found in the password, then it is rejected
# [MIN_FOR_POINT]: one point is granted if password contains at least [MIN_FOR_POINT] character numbers of this class
class-upperCase ABCDEFGHIJKLMNOPQRSTUVWXYZ 0 1
class-lowerCase abcdefghijklmnopqrstuvwxyz 0 1
class-digit 0123456789 0 1
class-special <>,?;.:/!§ù%*µ^¨$£²&é~"#'{([-|è`_\ç^à@)]°=}+ 0 1

Example

With this policy:

minQuality 4
forbiddenChars .?,
maxLength 0
checkRDN 1
class-upperCase ABCDEFGHIJKLMNOPQRSTUVWXYZ 0 5
class-lowerCase abcdefghijklmnopqrstuvwxyz 0 12
class-digit 0123456789 0 1
class-special <>,?;.:/!§ù%*µ^¨$£²&é~"#'{([-|è`_\ç^à@)]°=}+ 0 1
class-myClass :) 1 1``

the password

ThereIsNoCowLevel)

is working, because,

• it has 4 character classes validated : upper, lower, special, and myClass
• it has no character among .?,
• it has at least one character among : or )
• there is no size constraint (maxLength of 0)

but it won't work for the user uid=John Cowlevel,ou=people,cn=example,cn=com, because the token "Cowlevel" from his RDN exists in the password (case insensitive).

Logs

If a user password is rejected by ppm, the user will get this type of message:

Typical user message from ldappasswd(5): Result: Constraint violation (19) Additional info: Password for dn="%s" does not pass required number of strength checks (2 of 3)

A more detailed message is written to the server log.

Server log:

Jul 27 20:09:14 machine slapd[20270]: ppm: Opening file /etc/openldap/ppm.conf
Jul 27 20:09:14 machine slapd[20270]: ppm: Param = minQuality, value = 3, min = (null), minForPoint= (null)
Jul 27 20:09:14 machine slapd[20270]: ppm:  Accepted replaced value: 3
Jul 27 20:09:14 machine slapd[20270]: ppm: Param = forbiddenChars, value = , min = (null), minForPoint= (null)
Jul 27 20:09:14 machine slapd[20270]: ppm:  Accepted replaced value:
Jul 27 20:09:14 machine slapd[20270]: ppm: Param = class-upperCase, value = ABCDEFGHIJKLMNOPQRSTUVWXYZ, min = 0, minForPoint= 5
Jul 27 20:09:14 machine slapd[20270]: ppm:  Accepted replaced value: ABCDEFGHIJKLMNOPQRSTUVWXYZ
Jul 27 20:09:14 machine slapd[20270]: ppm: Param = class-lowerCase, value = abcdefghijklmnopqrstuvwxyz, min = 0, minForPoint= 12
Jul 27 20:09:14 machine slapd[20270]: ppm:  Accepted replaced value: abcdefghijklmnopqrstuvwxyz
Jul 27 20:09:14 machine slapd[20270]: ppm: Param = class-digit, value = 0123456789, min = 0, minForPoint= 1
Jul 27 20:09:14 machine slapd[20270]: ppm:  Accepted replaced value: 0123456789
Jul 27 20:09:14 machine slapd[20270]: ppm: Param = class-special, value = <>,?;.:/!§ù%*µ^¨$£²&é~"#'{([-|è`_\ç^à@)]°=}+, min = 0, minForPoint= 1
Jul 27 20:09:14 machine slapd[20270]: ppm:  Accepted replaced value: <>,?;.:/!§ù%*µ^¨$£²&é~"#'{([-|è`_\ç^à@)]°=}+
Jul 27 20:09:14 machine slapd[20270]: ppm: Param = class-myClass, value = :), min = 1, minForPoint= 1
Jul 27 20:09:14 machine slapd[20270]: ppm:  Accepted new value:
Jul 27 20:09:14 machine slapd[20270]: ppm: 1 point granted for class class-upperCase
Jul 27 20:09:14 machine slapd[20270]: ppm: 1 point granted for class class-lowerCase
Jul 27 20:09:14 machine slapd[20270]: ppm: 1 point granted for class class-digit

Tests

There is a unit test script: "unit_tests.sh" that illustrates checking some passwords. It is possible to test one particular password using directly the test program:

cd /usr/local/openldap/lib64
PPM_CONFIG_FILE=/usr/local/openldap/etc/openldap/ppm.conf LD_LIBRARY_PATH=. ./ppm_test "my_password" && echo OK

TODO

• integrate configuration file into cn=config

HISTORY

• 2017-05-19 David Coutadeur [email protected] Adds cracklib support Readme adaptations and cleaning Version 1.6
• 2017-02-07 David Coutadeur [email protected] Adds maxConsecutivePerClass (idea from Trevor Vaughan / [email protected]) Version 1.5
• 2016-08-22 David Coutadeur [email protected] Get config file from environment variable Version 1.4
• 2014-12-20 Daly Chikhaoui [email protected] Adding checkRDN parameter Version 1.3
• 2014-10-28 David Coutadeur [email protected] Adding maxLength parameter Version 1.2
• 2014-07-27 David Coutadeur [email protected] Changing the configuration file and the configuration data structure Version 1.1
• 2014-04-04 David Coutadeur [email protected] Version 1.0