Auth module (Enterprise)

Memgraph supports authentication and (optional) authorization using a custom built external auth module. The two supported operation modes are:

• authentication only (username/password verification)
• authentication and authorization (username/password verification and user to role mapping)

When a user connects to Memgraph the database will forward the user's supplied username and password to the external auth module and wait for it to deliver the authentication and/or authorization verdict back to the database. Based on the returned verdict, Memgraph will either close the connection to the connected user or it will allow the connection and set-up the user and/or role accordingly.

When Memgraph is switched to use the external auth module for authentication its internal users are automatically disabled. All users are authenticated only using the module, existing local users are ignored (unless they can be authenticated using the module).

As this is an Enterprise feature, once the Memgraph Enterprise license expires, newly created users will be granted all privileges. The existing users' privileges will still apply but you won't be able to manage them.

Authentication mode

In this mode, Memgraph will only perform authentication (verification of username and password) using the external auth module. All user-to-role mappings, as well as user and role permissions are managed through Memgraph.

When a user that has never logged into the database passes authentication using the external auth module, a user object is created for that user. The user can then be seen using the following query:

SHOW USERS;

This behavior can be changed to disable login for users that don't have an explicitly created user account.

Authorization mode

In this mode, Memgraph will perform both the authentication and authorization using the external auth module. The external module is used to determine user-to-role mappings, but user and role permissions are still managed through Memgraph.

When a user with a non-existing role within Memgraph logs into the database, that role object is created and assigned to the user.

The role can then be seen using the following query:

SHOW ROLES;

This behavior can be changed to disable login to users that don't have an explicitly created role.

Configuration flags

Use the following configuration flags to configure the external auth module authentication and authorization mechanisms used by Memgraph.

Communication

Memgraph uses inter-process pipes to communicate with the module. The module will receive auth requests on file descriptor 1000 and has to return auth responses to file descriptor 1001. The standard streams (stdin and stdout) aren't used because external libraries often tend to write something to stdout which is difficult to disable. By using separate file descriptors, stdout is left intact and can be used freely for debugging purposes (along with stderr).

The protocol used between Memgraph and the module is as follows:

• Each auth request is sent as a JSON encoded object in a single line that is terminated by a \n.
• Each auth response must be sent as a JSON encoded object in a single line that is terminated by a \n.
• Auth requests are objects that contain the following keys:
  • username - the user's username
  • password - the user's password
• Auth responses must be objects that contain the following keys:
  • authenticated - a bool indicating whether the user is allowed to log in to the database
  • role - a string indicating which role the user should have (must be supplied even when the module is used for authentication only)

If the external auth module crashes during the processing of an auth request, Memgraph won't allow the user to log in to the database and will automatically restart the auth module for the next auth request. All crash logs will be seen in Memgraph's output (typically in systemd logs using journalctl).

Example

This very simple example auth module is written in Python, but any programming language can be used.

#!/usr/bin/python3
import json
import io
 
 
def authenticate(username, password):
    return {"authenticated": True, "role": ""}
 
 
if __name__ == "__main__":
    input_stream = io.FileIO(1000, mode="r")
    output_stream = io.FileIO(1001, mode="w")
    while True:
        params = json.loads(input_stream.readline().decode("ascii"))
        ret = authenticate(**params)
        output_stream.write((json.dumps(ret) + "\n").encode("ascii"))

In the example you can see how the communication protocol works and you can see the function that is used for authentication (and authorization). When writing your own modules you have to reimplement the authenticate function according to your needs.

Because the authentication (and authorization) function has a simple signature, it is easy (and recommended) to write unit (or integration) tests in separate files. For example:

#!/usr/bin/python3
import module
 
assert module.authenticate("sponge", "bob") == {"authenticated": True, "role": ""}
assert module.authenticate("CHUCK", "NORRIS") == {"authenticated": True, "role": ""}

LDAP

Memgraph also supports authentication and authorization using LDAP with a built-in auth module that is packaged with Memgraph Enterprise.

The module supports two operation modes:

• authentication only (LDAP bind request)
• authentication and authorization (LDAP bind and search requests)

Authentication mode

When using LDAP authentication the module builds the DN used for authentication using the user specified username and the following formula:

DN = prefix + username + suffix

In most common situations the prefix will be cn= and the suffix will be ,dc=example,dc=com. With an example username alice that would yield a DN equal to cn=alice,dc=example,dc=com which will then be used for the LDAP bind operation with the user specified password.

Authorization mode

Authentication is performed in the same way as described above. After the user is authenticated, the module searches through the role mapping root DN object that contains role mappings. A role mapping object that has the current bound user as its member attribute is used as the user's role. The role that is mapped to the user is the CN attribute of the role mapping object. The attribute that contains the user DN in the mapping object, as well as the attribute that contains the role name, can be changed in the module configuration file to accommodate your LDAP schema.

When searching for a role in directories that have thousands of roles, the search process could take some time, causing long login times.

Module requirements

The module is written in Python 3 and it must be installed on the server. The Python version should be at least 3.5. Also, you must have the following Python 3 libraries installed:

• ldap3 - used to communicate with the LDAP server.
• PyYAML - used to parse the configuration file.

Module configuration

The module configuration file is located at /etc/memgraph/auth_module/ldap.yaml. An initial example configuration file that has all settings documented and explained is located at /etc/memgraph/auth_module/ldap.example.yaml. For quick setup, you can copy the example configuration file into the module configuration file.

Database configuration

In order to enable the use of the LDAP authentication and authorization module you have to set the flag --auth-module-executable to use /usr/lib/memgraph/auth_module/ldap.py.

Other flags that change the behavior of the database to module integration can be specified according to your needs.

Example

Organizations typically use an LDAP server to hold and manage the permissions. Because LDAP servers are already set-up in most large organizations, it is convenient for the organization to allow all staff members to have access to the database using the already available centralized user management system.

For this guide let's assume that we have an LDAP server that is serving the following data:

# Users root entry
dn: ou=people,dc=memgraph,dc=com
objectclass: organizationalUnit
objectclass: top
ou: people

# User dba
dn: cn=dba,ou=people,dc=memgraph,dc=com
cn: dba
objectclass: person
objectclass: top
sn: user
userpassword: dba

# User alice
dn: cn=alice,ou=people,dc=memgraph,dc=com
cn: alice
objectclass: person
objectclass: top
sn: user
userpassword: alice

# User bob
dn: cn=bob,ou=people,dc=memgraph,dc=com
cn: bob
objectclass: person
objectclass: top
sn: user
userpassword: bob

# User carol
dn: cn=carol,ou=people,dc=memgraph,dc=com
cn: carol
objectclass: person
objectclass: top
sn: user
userpassword: carol

# User dave
dn: cn=dave,ou=people,dc=memgraph,dc=com
cn: dave
objectclass: person
objectclass: top
sn: user
userpassword: dave

# Roles root entry
dn: ou=roles,dc=memgraph,dc=com
objectclass: organizationalUnit
objectclass: top
ou: roles

# Role moderator
dn: cn=moderator,ou=roles,dc=memgraph,dc=com
cn: moderator
member: cn=alice,ou=people,dc=memgraph,dc=com
objectclass: groupOfNames
objectclass: top

# Role admin
dn: cn=admin,ou=roles,dc=memgraph,dc=com
cn: admin
member: cn=carol,ou=people,dc=memgraph,dc=com
member: cn=dave,ou=people,dc=memgraph,dc=com
objectclass: groupOfNames
objectclass: top

To summarize, the dataset contains the following data:

• ou=people,dc=memgraph,dc=com - entry that holds all users.
  • cn=dba,ou=people,dc=memgraph,dc=com - user dba that will be used as the database administrator.
  • cn=alice,ou=people,dc=memgraph,dc=com - regular user alice.
  • cn=bob,ou=people,dc=memgraph,dc=com - regular user bob.
  • cn=carol,ou=people,dc=memgraph,dc=com - regular user carol.
  • cn=dave,ou=people,dc=memgraph,dc=com - regular user dave.
• ou=roles,dc=memgraph,dc=com - entry that holds all roles.
  • cn=moderator,ou=roles,dc=memgraph,dc=com - role moderator that has alice as its member.
  • cn=admin,ou=roles,dc=memgraph,dc=com - role admin that has carol and dave as its members.

Authentication

CREATE USER dba;
GRANT ALL PRIVILEGES TO dba;

--auth-module-executable=/usr/lib/memgraph/auth_module/ldap.py

server:
  host: "<LDAP_SERVER_HOSTNAME>"
  port: <LDAP_SERVER_PORT>
  encryption: "disabled"
  cert_file: ""
  key_file: ""
  ca_file: ""
  validate_cert: false
 
users:
  prefix: "cn="
  suffix: ",ou=people,dc=memgraph,dc=com"
 
roles:
  root_dn: ""
  root_objectclass: ""
  user_attribute: ""
  role_attribute: ""

GRANT MATCH TO alice;

MATCH (n) RETURN n;

--auth-ldap-create-user=false

CREATE USER alice;
CREATE USER bob;

Authorization

This example shows how to set-up the LDAP auth module to deduce the user's role using LDAP search queries.

roles:
  root_dn: "ou=roles,dc=memgraph,dc=com"
  root_objectclass: "groupOfNames"
  user_attribute: "member"
  role_attribute: "cn"

--auth-ldap-create-role=false

CREATE ROLE moderator;