SLAPD.ACCESS(5)SLAPD.ACCESS(5)NAMEslapd.access - access configuration for slapd, the stand-
alone LDAP daemon
SYNOPSIS
ETCDIR/slapd.conf
DESCRIPTION
The slapd.conf(5) file contains configuration information
for the slapd(8) daemon. This configuration file is also
used by the slurpd(8) replication daemon and by the SLAPD
tools slapadd(8), slapcat(8), and slapindex(8).
The slapd.conf file consists of a series of global config-
uration options that apply to slapd as a whole (including
all backends), followed by zero or more database backend
definitions that contain information specific to a backend
instance.
The general format of slapd.conf is as follows:
# 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
...
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.
For entries not held in any backend (such as a root DSE),
the directives of the first backend (and any global direc-
tives) are used.
Arguments that should be replaced by actual text are shown
in brackets <>. The structure of the access control
directives is
access to <what> [ by <who> <access> [ <control> ] ]+
Grant access (specified by <access>) to a set of
entries and/or attributes (specified by <what>) by
one or more requestors (specified by <who>).
The field <what> specifies the entity the access control
directive applies to. It can have the forms
*
[dn[.<dnstyle>]=<pattern>]
[filter=<ldapfilter>]
[attrs=<attrlist>]
The wildcard * stands for all the entries.
The statement dn=<pattern> selects the entries based on
their naming context. The optional style qualifier
<dnstyle> can be regex (the default) implies that pattern
is a regular expression, as detailed in regex(7), matching
a normalized string representation of the entry's DN. The
regex form of the pattern does not support UTF-8 yet.
For all other qualifiers, the pattern is a string repre-
sentation of the entry's DN. base or exact (an alias of
base) indicates the entry whose DN is equal to the pat-
tern. one to indicate all the entries immediately below
the pattern, subtree to indicate all entries in the sub-
tree at the pattern, children to indicate all entries
below (subordinate) to the pattern. Note that dn=".*" is
equivalent to *.
The statement filter=<ldapfilter> selects the entries
based on a valid LDAP filter as described in RFC 2254.
The statement attrs=<attrlist> selects the attributes the
access control rule applies to. It is a comma-separated
list of attribute types, plus the special names entry,
indicating access to the entry itself, and children, indi-
cating 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.
The last three 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 simulta-
neously.
The field <who> indicates whom the access rules apply to.
Multiple <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
*
anonymous
users
self
dn[.<dnstyle>[,<modifier>]]=<pattern>
dnattr=<attrname>
group[/<objectclass>[/<attrname>]]
[.<style>]=<pattern>
peername[.<style>]=<pattern>
sockname[.<style>]=<pattern>
domain[.<domainstyle>[,<modifier>]]=<pattern>
sockurl[.<style>]=<pattern>
set[.<style>]=<pattern>
ssf=<n>
transport_ssf=<n>
tls_ssf=<n>
sasl_ssf=<n>
aci=<attrname>
They may be specified in combination.
The wildcard * refers to everybody.
The keyword anonymous means access is granted to
unauthenticated users; it is moslty used to limit access
to authentication resources (e.g. the userPassword
attribute) to unauthenticated users for authentication
purposes.
The keyword users means access is granted to authenticated
users.
The keyword 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).
The statement dn=<pattern> means that access is granted to
the matching DN. The optional style qualifier dnstyle
allows the same choices of the dn form of the <what>
field. In addition, the regex form of pattern can exploit
substring substitution of submatches in the <what>
dn.regex clause by using the form $<digit>, with digit
ranging from 1 to 9.
The statement dnattr=<attrname> means that access is
granted to requests whose DN is listed in the entry being
accessed under the attrname attribute.
The statement group=<pattern> means that access is granted
to requests whose DN is listed in the group entry whose DN
is given by pattern. The optional parameters objectclass
and attrname define the objectClass and the member
attributeType of the group entry. The optional style
qualifier style can be regex, which means that pattern
will be expanded accorging to regex (7), and base or exact
(an alias of base), which means that exact match will be
used.
The statements peername=<pattern>, sockname=<pattern>,
domain=<pattern>, and sockurl=<pattern> mean that the con-
tacting host IP for peername, the named pipe file name for
sockname, the contacting host name for domain, and the
contacting URL for sockurl are compared against pattern to
determine access. The same style rules for pattern match
described for the group case apply. The domain clause
also allows the subtree style, which succeeds when a fully
qualified name exactly matches the domain pattern, or its
trailing part, after a dot, exactly matches the domain
pattern. The domain of the contacting host is determined
by performing a DNS reverse lookup. As this lookup can
easily be spoofed, use of the domain statement is strongly
discouraged. By default, reverse lookups are disabled.
The statement set=<pattern> is undocumented yet.
The statement aci=<attrname> means that the access control
is determined by the values in the attrname of the entry
itself. ACIs are experimental; they must be enabled at
compile time.
The statements ssf=<n>, transport_ssf=<n>, tls_ssf=<n>,
and sasl_ssf=<n> set the required Security Strength Factor
(ssf) required to grant access.
The field <access> ::= [self]{<level>|<priv>} determines
the access level or the specific access privileges the who
field will have. Its component are defined as
<level> ::= none|auth|compare|search|read|write
<priv> ::= {=|+|-}{w|r|s|c|x}+
The modifier self allows special operations like having a
certain access level or privilege only in case the opera-
tion involves the name of the user that's requesting the
access. It implies the user that requests access is
bound. An example is the 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.
The level access model relies on an incremental interpre-
tation of the access privileges. The possible levels are
none, auth, compare, search, read, and write. Each access
level implies all the preceding ones, thus write access
will imply all accesses. While none is trivial, auth
access means that one is allowed access to an attribute to
perform authentication/authorization operations (e.g.
bind) with no other access. This is useful to grant unau-
thenticated users the least possible access level to crit-
ical resources, like passwords.
The priv access model relies on the explicit setting of
access privileges for each clause. The = sign resets pre-
viously defined accesses; as a consequence, the final
access privileges will be only those defined by the
clause. The + and - signs add/remove access privileges to
the existing ones. The privileges are w for write, r for
read, s for search, c for compare, and x for authentica-
tion. More than one privilege can be added in one state-
ment.
The optional field <control> controls the flow of access
rule application. It can have the forms
stop
continue
break
where 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 continue form
allows for other <who> clauses in the same <access> clause
to be considered, so that they may result in incrementally
altering the privileges, while the break form allows for
other <access> clauses that match the same target to be
processed. Consider the (silly) example
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
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
access to dn.subtree="dc=example,dc=com" attrs=cn
by * =cs continue
by users +r
which grants everybody search and compare privileges, and
adds read privileges to authenticated clients.
CAVEATS
It is strongly recommended to explicitly use the most
appropriate DN style, to avoid possible incorrect specifi-
cations of the access rules as well as for performance
(avoid unrequired regex matching when an exact match suf-
fices) reasons.
An adminisistrator might create a rule of the form:
access to dn="dc=example,dc=com"
by ...
expecting it to match all entries in the subtree "dc=exam-
ple,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".
To match the desired subtree, the rule would be more pre-
cisely written:
access to dn.regex="^(.+,)?dc=example,dc=com$$"
by ...
For performance reasons, it would be better to use the
subtree style.
access to dn.subtree="dc=example,dc=com"
by ...
FILES
ETCDIR/slapd.conf
default slapd configuration file
SEE ALSOslapd(8),
"OpenLDAP Administrator's Guide" (http://www.OpenL-
DAP.org/doc/admin/)
ACKNOWLEDGEMENTS
OpenLDAP is developed and maintained by The OpenLDAP Pro-
ject (http://www.openldap.org/). OpenLDAP is derived from
University of Michigan LDAP 3.3 Release.
OpenLDAP LDVERSION RELEASEDATE SLAPD.ACCESS(5)
