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Re: Overlay supporting password syntax checking

Mathieu wrote:

I am currently migrating a users database to an OpenLDAP solution. I
have to deal with some constraints for this project, namely password
policy and/or password syntax checking.

Fortunately the ppolicy overlay already implements the
draft-behera-ldap-password-policy, and offers the possibility to use
pwdCheckModule to check password via external modules.

Unfortunately, I did not find any module meeting all my requirements:

The check_password() function, as defined in ppolicy, provides
to the underlying module two parameters:
- The entry being modified
- The new password.
Now to support per user settings, which is one of these requirements,
I have to either store extra attributes among each entry, or the module
has to perform a ldapsearch against the db.

An option is to modify the check_password() function so it sends the
ppolicy object itself:
int check_password (char *pPasswd, char **ppErrStr, Entry *pEntry,
Entry *ppolicyEntry);
This way people using external modules would just need to store their
settings attributes in it.

As I don't want to break existing modules implementation, I have
developed a simple overlay which enforces password syntax
checking on a per user or per database basis. The overlay implements
also the check_password() function so it can be used in conjunction
with ppolicy.

I believe the code is clean enough to be contributed and
I will be glad to upload it if you think it can be of any interest.
However, I have some questions first.

The overlay allows me to define a default password constraints
object at a database level, or a subentry in the user entry, in a similar way
as the ppolicy_default setting and the pwdPolicySubentry attributes.
This is so similar that I think it would be more relevant to extend
the ppolicy overlay so it could support basic syntax checking. I
understand the need to have the pwdCheckModule functionality, for
those in need of exotics or platform dependent checks, but counting
the characters belonging to a class is not harder than checking the
min/max length of the password.

So to summarize:

- Could the check_password function be modified?

Yes, but we would not release this change until OpenLDAP 2.5.

- Could basic syntax checking be integrated in ppolicy?

Maybe; please give more details on how you propose to specify the nature of each check.

And If none of these options are acceptable, should I upload the
overlay I developed?

You're always free to submit code to the ITS.

Of course I'm willing to help on the first two points.

  -- Howard Chu
  CTO, Symas Corp.           http://www.symas.com
  Director, Highland Sun     http://highlandsun.com/hyc/
  Chief Architect, OpenLDAP  http://www.openldap.org/project/