slapo-dynlist - Dynamic List overlay to slapd
The dynlist overlay to slapd(8) allows expansion of dynamic groups and
more. Any time an entry with a specific objectClass is being returned,
the LDAP URI-valued occurrences of a specific attribute are expanded
into the corresponding entries, and the values of the attributes listed
in the URI are added to the original entry. No recursion is allowed,
to avoid potential infinite loops. The resulting entry must comply
with the LDAP data model, so constraints are enforced. For example, if
a SINGLE-VALUE attribute is listed, only the first value results in the
final entry. The above described behavior is disabled when the
manageDSAit control (RFC 3296) is used. In that case, the contents of
the dynamic group entry is returned; namely, the URLs are returned
instead of being expanded.
The config directives that are specific to the dynlist overlay must be
prefixed by dynlist-, to avoid potential conflicts with directives
specific to the underlying database or to other stacked overlays.
This directive adds the dynlist overlay to the current database,
or to the frontend, if used before any database instantiation;
see slapd.conf(5) for details.
This slapd.conf configuration option is defined for the dynlist
overlay. It may have multiple occurrences, and it must appear after the
dynlist-attrset <group-oc> [<URI>] <URL-ad> [[<mapped-ad>:]<member-ad>
The value group-oc is the name of the objectClass that triggers
the dynamic expansion of the data.
The optional URI restricts expansion only to entries matching
the DN, the scope and the filter portions of the URI.
The value URL-ad is the name of the attributeDescription that
contains the URI that is expanded by the overlay; if none is
present, no expansion occurs. If the intersection of the
attributes requested by the search operation (or the asserted
attribute for compares) and the attributes listed in the URI is
empty, no expansion occurs for that specific URI. It must be a
subtype of labeledURI.
The value member-ad is optional; if present, the overlay behaves
as a dynamic group: this attribute will list the DN of the
entries resulting from the internal search. In this case, the
attrs portion of the URIs in the URL-ad attribute must be
absent, and the DNs of all the entries resulting from the
expansion of the URIs are listed as values of this attribute.
Compares that assert the value of the member-ad attribute of
entries with group-oc objectClass apply as if the DN of the
entries resulting from the expansion of the URI were present in
the group-oc entry as values of the member-ad attribute.
Alternatively, mapped-ad can be used to remap attributes
obtained through expansion. member-ad attributes are not filled
by expanded DN, but are remapped as mapped-ad attributes.
Multiple mapping statements can be used.
The dynlist overlay may be used with any backend, but it is mainly
intended for use with local storage backends. In case the URI
expansion is very resource-intensive and occurs frequently with well-
defined patterns, one should consider adding a proxycache later on in
the overlay stack.
By default the expansions are performed using the identity of the
current LDAP user. This identity may be overridden by setting the
dgIdentity attribute in the group's entry to the DN of another LDAP
user. In that case the dgIdentity will be used when expanding the URIs
in the object. Setting the dgIdentity to a zero-length string will
cause the expansions to be performed anonymously. Note that the
dgIdentity attribute is defined in the dyngroup schema, and this schema
must be loaded before the dgIdentity authorization feature may be used.
If the dgAuthz attribute is also present in the group's entry, its
values are used to determine what identities are authorized to use the
dgIdentity to expand the group. Values of the dgAuthz attribute must
conform to the (experimental) OpenLDAP authz syntax.
This example collects all the email addresses of a database into a
single entry; first of all, make sure that slapd.conf contains the
dynlist-attrset groupOfURLs memberURL
and that slapd loads dynlist.la, if compiled as a run-time module; then
add to the database an entry like
dn: cn=Dynamic List,ou=Groups,dc=example,dc=com
cn: Dynamic List
If no <attrs> are provided in the URI, all (non-operational) attributes
This example implements the dynamic group feature on the member
dynlist-attrset groupOfURLs memberURL member
A dynamic group with dgIdentity authorization could be created with an
dn: cn=Dynamic Group,ou=Groups,dc=example,dc=com
cn: Dynamic Group
dgIdentity: cn=Group Proxy,ou=Services,dc=example,dc=com
default slapd configuration file
slapd.conf(5), slapd-config(5), slapd(8). The slapo-dynlist(5) overlay
supports dynamic configuration via back-config.
This module was written in 2004 by Pierangelo Masarati for SysNet
Attribute remapping was contributed in 2008 by Emmanuel Dreyfus.