openldap/doc/man/man5/slapd.access.5

.TH SLAPD.ACCESS 5 "RELEASEDATE" "OpenLDAP LDVERSION"
.\" Copyright 1998-2003 The OpenLDAP Foundation All Rights Reserved.
.\" Copying restrictions apply.  See COPYRIGHT/LICENSE.
.SH NAME
slapd.access \- access configuration for slapd, the stand-alone LDAP daemon
.SH SYNOPSIS
ETCDIR/slapd.conf
.SH DESCRIPTION
The 
.BR slapd.conf (5)
file contains configuration information for the
.BR slapd (8)
daemon. This configuration file is also used by the
.BR slurpd (8)
replication daemon and by the SLAPD tools
.BR slapadd (8),
.BR slapcat (8),
and
.BR slapindex (8).
.LP
The
.B slapd.conf
file consists of a series of global configuration options that apply to
.B slapd
as a whole (including all backends), followed by zero or more database
backend definitions that contain information specific to a backend
instance.
.LP
The general format of
.B slapd.conf
is as follows:
.LP
.nf
    # comment - these options apply to every database
    <global configuration options>
    # first database definition & configuration options
    database    <backend 1 type>
    <configuration options specific to backend 1>
    # subsequent database definitions & configuration options
    ...
.fi
.LP
Both the global configuration and each backend-specific section can
contain access information.  Backend-specific access control
directives are used for those entries that belong to the backend,
according to their naming context.  In case no access control
directives are defined for a backend or those which are defined are
not applicable, the directives from the global configuration section
are then used.
.LP
For entries not held in any backend (such as a root DSE), the
directives of the first backend (and any global directives) are
used.
.LP
Arguments that should be replaced by actual text are shown in
brackets <>.  The structure of the access control directives is
.TP
.B access to <what> "[ by <who> <access> [ <control> ] ]+"
Grant access (specified by 
.BR <access> ) 
to a set of entries and/or attributes (specified by 
.BR <what> ) 
by one or more requestors (specified by 
.BR <who> ).
.LP
The field
.BR <what>
specifies the entity the access control directive applies to.
It can have the forms
.LP
.nf
	*
	[dn[.<dnstyle>]=<DN>] 
	[filter=<ldapfilter>]
	[attrs=<attrlist>]
.fi
.LP
The wildcard
.B *
stands for all the entries.
.LP
The statement
.B dn=<DN>
selects the entries based on their naming context.
The pattern is a string representation of the entry's DN.
.BR base ,
the default,
or
.B exact 
(an alias of 
.BR base )
indicates the entry whose DN is equal to the pattern.
.B one
indicates all the entries immediately below the
.BR pattern ,
.B subtree
indicates all entries in the subtree at the pattern,
.B children
indicates all the entries below (subordinate to) the pattern.
.LP
If the
.B <dnstyle>
qualifier is
.BR regex ,
then the value is a regular expression pattern,
as detailed in
.BR regex (7),
matching a normalized string representation of the entry's DN.
The regex form of the pattern does not (yet) support UTF-8.
.LP
The statement
.B filter=<ldapfilter>
selects the entries based on a valid LDAP filter as described in RFC 2254.
.LP
The statement
.B attrs=<attrlist>
selects the attributes the access control rule applies to.
It is a comma-separated list of attribute types, plus the special names
.BR entry ,
indicating access to the entry itself, and
.BR children ,
indicating access to the entry's children. ObjectClass names may also
be specified in this list, which will affect all the attributes that
are required and/or allowed by that objectClass.
.LP
Using the form
.B attrs=<attr> val[.<style>]=<value>
specifies access to a particular value of a single attribute.
In this case, only a single attribute type may be given. A value
.B <style>
of
.B exact
(the default) uses the attribute's equality matching rule to compare the
value. If the
.B <style>
is
.BR regex ,
the provided value is used as a regular expression pattern.
.LP
The dn, filter, and attrs statements are additive; they can be used in sequence 
to select entities the access rule applies to based on naming context,
value and attribute type simultaneously.
.LP
The field
.B <who>
indicates whom the access rules apply to.
Multiple 
.B <who>
statements can appear in an access control statement, indicating the
different access privileges to the same resource that apply to different
accessee.
It can have the forms
.LP
.nf
	*
	anonymous
	users
	self

	dn[.<dnstyle>[,<modifier>]]=<DN>
	dnattr=<attrname>
	group[/<objectclass>[/<attrname>]]
		[.<style>]=<group>
	peername[.<style>]=<peername>
	sockname[.<style>]=<sockname>
	domain[.<domainstyle>[,<modifier>]]=<domain>
	sockurl[.<style>]=<sockurl>
	set[.<style>]=<pattern>

	ssf=<n>
	transport_ssf=<n>
	tls_ssf=<n>
	sasl_ssf=<n>

	aci=<attrname>
.fi
.LP
They may be specified in combination.
.LP
.nf
.fi
.LP
The wildcard
.B *
refers to everybody.
.LP
The keyword
.B anonymous
means access is granted to unauthenticated clients; it is mostly used 
to limit access to authentication resources (e.g. the
.B userPassword
attribute) to unauthenticated clients for authentication purposes.
.LP
The keyword
.B users
means access is granted to authenticated clients.
.LP
The keyword
.B self
means access to an entry is allowed to the entry itself (e.g. the entry
being accessed and the requesting entry must be the same).
.LP
The statement
.B dn=<DN>
means that access is granted to the matching DN.
The optional style qualifier
.B dnstyle
allows the same choices of the dn form of the
.B <what>
field.  In addition, the
.B regex
style can exploit substring substitution of submatches in the
.B <what>
dn.regex clause by using the form
.BR $<digit> ,
with 
.B digit
ranging from 1 to 9.
.LP
The statement
.B dnattr=<attrname>
means that access is granted to requests whose DN is listed in the
entry being accessed under the 
.B <attrname>
attribute.
.LP
The statement
.B group=<group>
means that access is granted to requests whose DN is listed
in the group entry whose DN is given by
.BR <group> .
The optional parameters
.B <objectclass>
and
.B <attrname>
define the objectClass and the member attributeType of the group entry.
The optional style qualifier
.B <style>
can be
.BR regex ,
which means that
.B <group>
will be expanded according to regex (7), and
.B base
or
.B exact
(an alias of
.BR base ),
which means that exact match will be used.
.LP
For static groups, the specified attributeType must have
.B DistinguishedName
or
.B NameAndOptionalUID
syntax. For dynamic groups the attributeType must
be a subtype of the
.B labeledURI
attributeType. Only LDAP URIs of the form
.B ldap:///<base>??<scope>?<filter>
will be evaluated in a dynamic group.
.LP
The statements
.BR peername=<peername> ,
.BR sockname=<sockname> ,
.BR domain=<domain> ,
and
.BR sockurl=<sockurl>
mean that the contacting host IP for
.BR peername ,
the named pipe file name for
.BR sockname ,
the contacting host name for
.BR domain ,
and the contacting URL for
.BR sockurl
are compared against
.B pattern
to determine access.
The same
.B style
rules for pattern match described for the
.B group
case apply. 
The
.BR domain 
clause also allows the
.B subtree
style, which succeeds when a fully qualified name exactly matches the
.BR domain
pattern, or its trailing part, after a 
.BR dot ,
exactly matches the 
.BR domain
pattern.
The
.B domain
of the contacting host is determined by performing a DNS reverse lookup.
As this lookup can easily be spoofed, use of the
.B domain
statement is strongly discouraged.  By default, reverse lookups are disabled.
.LP
The statement
.B set=<pattern>
is undocumented yet.
.LP
The statement
.B aci=<attrname>
means that the access control is determined by the values in the
.B attrname
of the entry itself.
ACIs are experimental; they must be enabled at compile time.
.LP
The statements
.BR ssf=<n> ,
.BR transport_ssf=<n> ,
.BR tls_ssf=<n> ,
and
.BR sasl_ssf=<n>
set the required Security Strength Factor (ssf) required to grant access.
.LP
The field
.B <access> ::= [self]{<level>|<priv>}
determines the access level or the specific access privileges the
.B who 
field will have.
Its component are defined as
.LP
.nf
	<level> ::= none|auth|compare|search|read|write
	<priv> ::= {=|+|-}{w|r|s|c|x}+
.fi
.LP
The modifier
.B self
allows special operations like having a certain access level or privilege
only in case the operation involves the name of the user that's requesting
the access.
It implies the user that requests access is bound.
An example is the
.B selfwrite
access to the member attribute of a group, which allows one to add/delete
its own DN from the member list of a group, without affecting other members.
.LP
The 
.B level 
access model relies on an incremental interpretation of the access
privileges.
The possible levels are
.BR none ,
.BR auth ,
.BR compare ,
.BR search ,
.BR read ,
and
.BR write .
Each access level implies all the preceding ones, thus 
.B write
access will imply all accesses.
While
.B none
is trivial, 
.B auth
access means that one is allowed access to an attribute to perform
authentication/authorization operations (e.g.
.BR bind )
with no other access.
This is useful to grant unauthenticated clients the least possible 
access level to critical resources, like passwords.
.LP
The
.B priv
access model relies on the explicit setting of access privileges
for each clause.
The
.B =
sign resets previously defined accesses; as a consequence, the final 
access privileges will be only those defined by the clause.
The 
.B +
and
.B -
signs add/remove access privileges to the existing ones.
The privileges are
.B w
for write,
.B r
for read,
.B s 
for search,
.B c 
for compare, and
.B x
for authentication.
More than one privilege can be added in one statement.
.LP
The optional field
.B <control>
controls the flow of access rule application.
It can have the forms
.LP
.nf
	stop
	continue
	break
.fi
.LP
where
.BR stop ,
the default, means access checking stops in case of match.
The other two forms are used to keep on processing access clauses.
In detail, the
.B continue
form allows for other 
.B <who>
clauses in the same 
.B <access>
clause to be considered, so that they may result in incrementally altering
the privileges, while the
.B break
form allows for other
.B <access>
clauses that match the same target to be processed.
Consider the (silly) example
.LP
.nf
	access to dn.subtree="dc=example,dc=com" attrs=cn
		by * =cs break

	access to dn.subtree="ou=People,dc=example,dc=com"
		by * +r
.fi
.LP
which allows search and compare privileges to everybody under
the "dc=example,dc=com" tree, with the second rule allowing
also read in the "ou=People" subtree,
or the (even more silly) example
.LP
.nf
	access to dn.subtree="dc=example,dc=com" attrs=cn
		by * =cs continue
		by users +r
.fi
.LP
which grants everybody search and compare privileges, and adds read
privileges to authenticated clients.
.SH CAVEATS
It is strongly recommended to explicitly use the most appropriate
DN 
.BR style ,
to avoid possible incorrect specifications of the access rules as well
as for performance (avoid unrequired regex matching when an exact
match suffices) reasons.
.LP
An adminisistrator might create a rule of the form:
.LP
.nf
	access to dn.regex="dc=example,dc=com"
		by ...
.fi
.LP
expecting it to match all entries in the subtree "dc=example,dc=com".
However, this rule actually matches any DN which contains anywhere
the substring "dc=example,dc=com".  That is, the rule matches both
"uid=joe,dc=example,dc=com" and "dc=example,dc=com,uid=joe".
.LP
To match the desired subtree, the rule would be more precisely
written:
.LP
.nf
	access to dn.regex="^(.+,)?dc=example,dc=com$$"
		by ...
.fi
.LP
For performance reasons, it would be better to use the subtree style.
.LP
.nf
	access to dn.subtree="dc=example,dc=com"
		by ...
.fi
.LP
.SH FILES
.TP
ETCDIR/slapd.conf
default slapd configuration file
.SH SEE ALSO
.BR slapd (8),
.LP
"OpenLDAP Administrator's Guide" (http://www.OpenLDAP.org/doc/admin/)
.SH ACKNOWLEDGEMENTS
.B OpenLDAP
is developed and maintained by The OpenLDAP Project (http://www.openldap.org/).
.B OpenLDAP
is derived from University of Michigan LDAP 3.3 Release.