SLAPD.ACCESS(5)SLAPD.ACCESS(5)NAMEslapd.access - access configuration for slapd, the stand-alone LDAP
daemon
SYNOPSIS
/etc/openldap/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 configuration
options that apply to slapd as a whole (including all backends), fol‐
lowed by zero or more database backend definitions that contain infor‐
mation 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 direc‐
tives from the global configuration section are then used.
For entries not held in any backend (such as a root DSE), the direc‐
tives of the first backend (and any global directives) 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 representation of the
entry's DN. base or exact (an alias of base) indicates the entry whose
DN is equal to the pattern. one to indicate all the entries immedi‐
ately below the pattern, subtree to indicate all entries in the subtree
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 con‐
trol 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, 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.
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 simultaneously.
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 dif‐
ferent 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 pat‐
tern 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 attr‐
name 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=<pat‐
tern>, and sockurl=<pattern> mean that the contacting host IP for peer‐
name, 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 eas‐
ily 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 deter‐
mined 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 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 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 interpretation 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 triv‐
ial, 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 unauthenticated users the least
possible access level to critical resources, like passwords.
The priv access model relies on the explicit setting of access privi‐
leges for each clause. The = sign resets previously 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 authentication. More than one
privilege can be added in one statement.
The optional field <control> controls the flow of access rule applica‐
tion. 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 incremen‐
tally 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 specifications of the access rules
as well as for performance (avoid unrequired regex matching when an
exact match suffices) 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=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".
To match the desired subtree, the rule would be more precisely 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
/etc/openldap/slapd.conf
default slapd configuration file
SEE ALSOslapd(8),
"OpenLDAP Administrator's Guide" (http://www.OpenLDAP.org/doc/admin/)
ACKNOWLEDGEMENTS
OpenLDAP is developed and maintained by The OpenLDAP Project
(http://www.openldap.org/). OpenLDAP is derived from University of
Michigan LDAP 3.3 Release.
OpenLDAP 2.1.X RELEASEDATE SLAPD.ACCESS(5)