Ubuntu Manpage: slapo-unique - Attribute Uniqueness overlay to slapd

Provided by: slapd_2.5.18+dfsg-0ubuntu0.22.04.2_amd64

NAME

       slapo-unique - Attribute Uniqueness overlay to slapd

SYNOPSIS

       /etc/ldap/slapd.conf

DESCRIPTION

       The  Attribute Uniqueness overlay can be used with a backend database such as slapd-mdb(5)
       to enforce the uniqueness of some or all attributes within a scope. This subtree  defaults
       to  all  objects  within  the  subtree of the database for which the Uniqueness overlay is
       configured.

       Uniqueness is enforced by  searching  the  subtree  to  ensure  that  the  values  of  all
       attributes  presented with an add, modify or modrdn operation are unique within the scope.
       For example, if uniqueness were enforced for the  uid  attribute,  the  subtree  would  be
       searched  for any other records which also have a uid attribute containing the same value.
       If any are found, the request is rejected.

       The search is performed using the rootdn of  the  database,  to  avoid  issues  with  ACLs
       preventing  the  overlay  from seeing all of the relevant data. As such, the database must
       have a rootdn configured.

CONFIGURATION

These slapd.conf options apply to the Attribute Uniqueness overlay. They should appear
after the overlay directive.

unique_uri <[strict ][ignore ][serialize ]URI[[ URI...]...]>
Configure the base, attributes, scope, and filter for uniqueness checking.
Multiple URIs may be specified within a domain, allowing complex selections of
objects. Multiple unique_uri statements or olcUniqueURI attribute values will
create independent domains, each with their own independent lists of URIs and
ignore/strict settings.

Keywords strict, ignore, and serialize have to be enclosed in quotes (") together
with the URI when using deprecated slapd.conf configurations.

The LDAP URI syntax is a subset of RFC-4516, and takes the form:

ldap:///[base dn]?[attributes...]?scope[?filter]

The base dn defaults to that of the back-end database. Specified base dns must be
within the subtree of the back-end database.

If no attributes are specified, the URI applies to all non-operational attributes.

The scope component is effectively mandatory, because LDAP URIs default to base
scope, which is not valid for uniqueness, because groups of one object are always
unique. Scopes of sub (for subtree) and one for one-level are valid.

The filter component causes the domain to apply uniqueness constraints only to
matching objects. e.g. ldap:///?cn?sub?(sn=e*) would require unique cn attributes
for all objects in the subtree of the back-end database whose sn starts with an e.

It is possible to assert uniqueness upon all non-operational attributes except
those listed by prepending the keyword ignore If not configured, all non-
operational (e.g., system) attributes must be unique. Note that the attributes list
of an ignore URI should generally contain the objectClass, dc, ou and o attributes,
as these will generally not be unique, nor are they operational attributes.

It is possible to set strict checking for the uniqueness domain by prepending the
keyword strict. By default, uniqueness is not enforced for null values. Enabling
strict mode extends the concept of uniqueness to include null values, such that
only one attribute within a subtree will be allowed to have a null value.
Strictness applies to all URIs within a uniqueness domain, but some domains may be
strict while others are not.

It is possible to enforce strict serialization of modifications by prepending the
keyword serialize. By default, no serialization is performed, so multiple
modifications occurring nearly simultaneously may see incomplete uniqueness
results. Using serialize will force individual write operations to fully complete
before allowing any others to proceed, to ensure that each operation's uniqueness
checks are consistent.

It is not possible to set both URIs and legacy slapo-unique configuration parameters
simultaneously. In general, the legacy configuration options control pieces of a single
unfiltered subtree domain.

unique_base <basedn>
This legacy configuration parameter should be converted to the base dn component of
the above unique_uri style of parameter.

unique_ignore <attribute...>
This legacy configuration parameter should be converted to a unique_uri parameter
with ignore keyword as described above.

unique_attributes <attribute...>
This legacy configuration parameter should be converted to a unique_uri parameter,
as described above.

unique_strict <attribute...>
This legacy configuration parameter should be converted to a strict keyword
prepended to a unique_uri parameter, as described above.

CAVEATS

       unique_uri cannot be used with the old-style of configuration, and vice versa.  unique_uri
       can implement everything the older system can do, however.

       Typical attributes for the ignore ldap:///...  URIs are intentionally not  hardcoded  into
       the overlay to allow for maximum flexibility in meeting site-specific requirements.

       Replication  and operations with the relax control are allowed to bypass this enforcement.
       It is therefore important that all servers accepting writes have this  overlay  configured
       in order to maintain uniqueness in a replicated DIT.

FILES