SLAPD.ACCESS(5) File Formats Manual SLAPD.ACCESS(5)
slapd.access - access configuration for slapd, the stand-alone LDAP
daemon
ETCDIR/slapd.conf
The slapd.conf(5) file contains configuration information for the
slapd(8) daemon. This configuration file is also used by the SLAPD
tools slapacl(8), slapadd(8), slapauth(8), slapcat(8), slapdn(8),
slapindex(8), and slaptest(8).
The slapd.conf file consists of a series of global configuration
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.
If no access controls are present, the default policy allows anyone
and everyone to read anything but restricts updates to rootdn.
(e.g., "access to * by * read").
When dealing with an access list, because the global access list is
effectively appended to each per-database list, if the resulting list
is non-empty then the access list will end with an implicit access to
* by * none directive. If there are no access directives applicable
to a backend, then a default read is used.
Be warned: the rootdn can always read and write EVERYTHING!
For entries not held in any backend (such as a root DSE), the 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>).
Lists of access directives are evaluated in the order they appear in
slapd.conf. When a <what> clause matches the datum whose access is
being evaluated, its <who> clause list is checked. When a <who>
clause matches the accessor's properties, its <access> and <control>
clauses are evaluated. Access control checking stops at the first
match of the <what> and <who> clause, unless otherwise dictated by
the <control> clause. Each <who> clause list is implicitly
terminated by a
by * none stop
clause that results in stopping the access control with no access
privileges granted. Each <what> clause list is implicitly terminated
by a
access to *
by * none
clause that results in granting no access privileges to an otherwise
unspecified datum.
The field <what> specifies the entity the access control directive
applies to. It can have the forms
dn[.<dnstyle>]=<dnpattern>
filter=<ldapfilter>
attrs=<attrlist>[ val[/matchingRule][.<attrstyle>]=<attrval>]
with
<dnstyle>={{exact|base(object)}|regex
|one(level)|sub(tree)|children}
<attrlist>={<attr>|[{!|@}]<objectClass>}[,<attrlist>]
<attrstyle>={{exact|base(object)}|regex
|one(level)|sub(tree)|children}
The statement dn=<dnpattern> selects the entries based on their
naming context. The <dnpattern> is a string representation of the
entry's DN. The wildcard * stands for all the entries, and it is
implied if no dn form is given.
The <dnstyle> is optional; however, it is recommended to specify it
to avoid ambiguities. Base (synonym of baseObject), the default, or
exact (an alias of base) indicates the entry whose DN is equal to the
<dnpattern>; one (synonym of onelevel) indicates all the entries
immediately below the <dnpattern>, sub (synonym of subtree) indicates
all entries in the subtree at the <dnpattern>, children indicates all
the entries below (subordinate to) the <dnpattern>.
If the <dnstyle> qualifier is regex, then <dnpattern> is a POSIX
(''extended'') regular expression pattern, as detailed in regex(7)
and/or re_format(7), matching a normalized string representation of
the entry's DN. The regex form of the pattern does not (yet) support
UTF-8.
The statement filter=<ldapfilter> selects the entries based on a
valid LDAP filter as described in RFC 4515. A filter of
(objectClass=*) is implied if no filter form is given.
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, 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. Actually, names in <attrlist> that are prefixed by @
are directly treated as objectClass names. A name prefixed by ! is
also treated as an objectClass, but in this case the access rule
affects the attributes that are not required nor allowed by that
objectClass. If no attrs form is given, attrs=@extensibleObject is
implied, i.e. all attributes are addressed.
Using the form attrs=<attr>
val[/matchingRule][.<attrstyle>]=<attrval> specifies access to a
particular value of a single attribute. In this case, only a single
attribute type may be given. The <attrstyle> exact (the default) uses
the attribute's equality matching rule to compare the value, unless a
different (and compatible) matching rule is specified. If the
<attrstyle> is regex, the provided value is used as a POSIX
(''extended'') regular expression pattern. If the attribute has DN
syntax, the <attrstyle> can be any of base, onelevel, subtree or
children, resulting in base, onelevel, subtree or children match,
respectively.
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. Submatches
resulting from regex matching can be dereferenced in the <who> field
using the syntax ${v<n>}, where <n> is the submatch number. The
default syntax, $<n>, is actually an alias for ${d<n>}, that
corresponds to dereferencing submatches from the dnpattern portion of
the <what> field.
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[.<selfstyle>]
dn[.<dnstyle>[,<modifier>]]=<DN>
dnattr=<attrname>
realanonymous
realusers
realself[.<selfstyle>]
realdn[.<dnstyle>[,<modifier>]]=<DN>
realdnattr=<attrname>
group[/<objectclass>[/<attrname>]]
[.<groupstyle>]=<group>
peername[.<peernamestyle>]=<peername>
sockname[.<style>]=<sockname>
domain[.<domainstyle>[,<modifier>]]=<domain>
sockurl[.<style>]=<sockurl>
set[.<setstyle>]=<pattern>
ssf=<n>
transport_ssf=<n>
tls_ssf=<n>
sasl_ssf=<n>
dynacl/<name>[/<options>][.<dynstyle>][=<pattern>]
with
<style>={exact|regex|expand}
<selfstyle>={level{<n>}}
<dnstyle>={{exact|base(object)}|regex
|one(level)|sub(tree)|children|level{<n>}}
<groupstyle>={exact|expand}
<peernamestyle>={<style>|ip|ipv6|path}
<domainstyle>={exact|regex|sub(tree)}
<setstyle>={exact|expand}
<modifier>={expand}
<name>=aci <pattern>=<attrname>]
They may be specified in combination.
The wildcard * refers to everybody.
The keywords prefixed by real act as their counterparts without
prefix; the checking respectively occurs with the authentication DN
and the authorization DN.
The keyword anonymous means access is granted to unauthenticated
clients; it is mostly used to limit access to authentication
resources (e.g. the userPassword attribute) to unauthenticated
clients for authentication purposes.
The keyword users means access is granted to authenticated clients.
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). It allows the level{<n>} style, where <n> indicates
what ancestor of the DN is to be used in matches. A positive value
indicates that the <n>-th ancestor of the user's DN is to be
considered; a negative value indicates that the <n>-th ancestor of
the target is to be considered. For example, a "by self.level{1}
..." clause would match when the object "dc=example,dc=com" is
accessed by "cn=User,dc=example,dc=com". A "by self.level{-1} ..."
clause would match when the same user accesses the object "ou=Address
Book,cn=User,dc=example,dc=com".
The statement dn=<DN> 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 style can
exploit substring substitution of submatches in the <what> dn.regex
clause by using the form $<digit>, with digit ranging from 0 to 9
(where 0 matches the entire string), or the form ${<digit>+}, for
submatches higher than 9. Substring substitution from attribute
value can be done in using the form ${v<digit>+}. Since the dollar
character is used to indicate a substring replacement, the dollar
character that is used to indicate match up to the end of the string
must be escaped by a second dollar character, e.g.
access to dn.regex="^(.+,)?uid=([^,]+),dc=[^,]+,dc=com$"
by dn.regex="^uid=$2,dc=[^,]+,dc=com$$" write
The style qualifier allows an optional modifier. At present, the
only type allowed is expand, which causes substring substitution of
submatches to take place even if dnstyle is not regex. Note that the
regex dnstyle in the above example may be of use only if the <by>
clause needs to be a regex; otherwise, if the value of the second
(from the right) dc= portion of the DN in the above example were
fixed, the form
access to dn.regex="^(.+,)?uid=([^,]+),dc=example,dc=com$"
by dn.exact,expand="uid=$2,dc=example,dc=com" write
could be used; if it had to match the value in the <what> clause, the
form
access to dn.regex="^(.+,)?uid=([^,]+),dc=([^,]+),dc=com$"
by dn.exact,expand="uid=$2,dc=$3,dc=com" write
could be used.
Forms of the <what> clause other than regex may provide submatches as
well. The base(object), the sub(tree), the one(level), and the
children forms provide $0 as the match of the entire string. The
sub(tree), the one(level), and the children forms also provide $1 as
the match of the rightmost part of the DN as defined in the <what>
clause. This may be useful, for instance, to provide access to all
the ancestors of a user by defining
access to dn.subtree="dc=com"
by dn.subtree,expand="$1" read
which means that only access to entries that appear in the DN of the
<by> clause is allowed.
The level{<n>} form is an extension and a generalization of the
onelevel form, which matches all DNs whose <n>-th ancestor is the
pattern. So, level{1} is equivalent to onelevel, and level{0} is
equivalent to base.
It is perfectly useless to give any access privileges to a DN that
exactly matches the rootdn of the database the ACLs apply to, because
it implicitly possesses write privileges for the entire tree of that
database. Actually, access control is bypassed for the rootdn, to
solve the intrinsic chicken-and-egg problem.
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=<group> means that access is granted to requests
whose DN is listed in the group entry whose DN is given by <group>.
The optional parameters <objectclass> and <attrname> define the
objectClass and the member attributeType of the group entry. The
defaults are groupOfNames and member, respectively. The optional
style qualifier <style> can be expand, which means that <group> will
be expanded as a replacement string (but not as a regular expression)
according to regex(7) and/or re_format(7), and exact, which means
that exact match will be used. If the style of the DN portion of the
<what> clause is regex, the submatches are made available according
to regex(7) and/or re_format(7); other styles provide limited
submatches as discussed above about the DN form of the <by> clause.
For static groups, the specified attributeType must have
DistinguishedName or NameAndOptionalUID syntax. For dynamic groups
the attributeType must be a subtype of the labeledURI attributeType.
Only LDAP URIs of the form ldap:///<base>??<scope>?<filter> will be
evaluated in a dynamic group, by searching the local server only.
The statements peername=<peername>, sockname=<sockname>,
domain=<domain>, and sockurl=<sockurl> mean that the contacting host
IP (in the form IP=<ip>:<port> for IPv4, or IP=[<ipv6>]:<port> for
IPv6) or the contacting host named pipe file name (in the form
PATH=<path> if connecting through a named pipe) 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, plus the regex style, which
implies submatch expand and regex match of the corresponding
connection parameters. The exact style of the <peername> clause (the
default) implies a case-exact match on the client's IP, including the
IP= prefix and the trailing :<port>, or the client's path, including
the PATH= prefix if connecting through a named pipe. The special ip
style interprets the pattern as <peername>=<ip>[%<mask>][{<n>}],
where <ip> and <mask> are dotted digit representations of the IP and
the mask, while <n>, delimited by curly brackets, is an optional
port. The same applies to IPv6 addresses when the special ipv6 style
is used. When checking access privileges, the IP portion of the
peername is extracted, eliminating the IP= prefix and the :<port>
part, and it is compared against the <ip> portion of the pattern
after masking with <mask>: ((peername & <mask>) == <ip>). As an
example, peername.ip=127.0.0.1 and peername.ipv6=::1 allow
connections only from localhost,
peername.ip=192.168.1.0%255.255.255.0 allows connections from any IP
in the 192.168.1 class C domain, and
peername.ip=192.168.1.16%255.255.255.240{9009} allows connections
from any IP in the 192.168.1.[16-31] range of the same domain, only
if port 9009 is used. The special path style eliminates the PATH=
prefix from the peername when connecting through a named pipe, and
performs an exact match on the given pattern. 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 expand style is
allowed, implying an exact match with submatch expansion; the use of
expand as a style modifier is considered more appropriate. As an
example, domain.subtree=example.com will match www.example.com, but
will not match www.anotherexample.com. 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 optional
domainstyle qualifier of the <domain> clause allows a modifier
option; the only value currently supported is expand, which causes
substring substitution of submatches to take place even if the
domainstyle is not regex, much like the analogous usage in <dn>
clause.
The statement set=<pattern> is undocumented yet.
The statement dynacl/<name>[/<options>][.<dynstyle>][=<pattern>]
means that access checking is delegated to the admin-defined method
indicated by <name>, which can be registered at run-time by means of
the moduleload statement. The fields <options>, <dynstyle> and
<pattern> are optional, and are directly passed to the registered
parsing routine. Dynacl is experimental; it must be enabled at
compile time.
The statement dynacl/aci[=<attrname>] means that the access control
is determined by the values in the attrname of the entry itself. The
optional <attrname> indicates what attributeType holds the ACI
information in the entry. By default, the OpenLDAPaci operational
attribute is used. 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 minimum required Security Strength Factor (ssf)
needed to grant access. The value should be positive integer.
The optional field <access> ::= [[real]self]{<level>|<priv>}
determines the access level or the specific access privileges the who
field will have. Its component are defined as
<level> ::= none|disclose|auth|compare|search|read|{write|add|delete}|manage
<priv> ::= {=|+|-}{0|d|x|c|s|r|{w|a|z}|m}+
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 authorized. The modifier realself refers to
the authenticated DN as opposed to the authorized DN of the self
modifier. 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, while being not allowed to affect other members.
The level access model relies on an incremental interpretation of the
access privileges. The possible levels are none, disclose, auth,
compare, search, read, write, and manage. Each access level implies
all the preceding ones, thus manage grants all access including
administrative access. The write access is actually the combination
of add and delete, which respectively restrict the write privilege to
add or delete the specified <what>.
The none access level disallows all access including disclosure on
error.
The disclose access level allows disclosure of information on error.
The auth access level 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
clients the least possible access level to critical resources, like
passwords.
The priv access model relies on the explicit setting of access
privileges 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 m for manage, w
for write, a for add, z for delete, r for read, s for search, c for
compare, x for authentication, and d for disclose. More than one of
the above privileges can be added in one statement. 0 indicates no
privileges and is used only by itself (e.g., +0). Note that +az is
equivalent to +w.
If no access is given, it defaults to +0.
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.
One useful application is to easily grant write privileges to an
updatedn that is different from the rootdn. In this case, since the
updatedn needs write access to (almost) all data, one can use
access to *
by dn.exact="cn=The Update DN,dc=example,dc=com" write
by * break
as the first access rule. As a consequence, unless the operation is
performed with the updatedn identity, control is passed straight to
the subsequent rules.
Operations require different privileges on different portions of
entries. The following summary applies to primary database backends
such as the BDB and HDB backends. Requirements for other backends
may (and often do) differ.
The add operation requires add (=a) privileges on the pseudo-
attribute entry of the entry being added, and add (=a) privileges on
the pseudo-attribute children of the entry's parent. When adding the
suffix entry of a database, add access to children of the empty DN
("") is required. Also if Add content ACL checking has been
configured on the database (see the slapd.conf(5) or slapd-config(5)
manual page), add (=a) will be required on all of the attributes
being added.
The bind operation, when credentials are stored in the directory,
requires auth (=x) privileges on the attribute the credentials are
stored in (usually userPassword).
The compare operation requires compare (=c) privileges on the
attribute that is being compared.
The delete operation requires delete (=z) privileges on the pseudo-
attribute entry of the entry being deleted, and delete (=d)
privileges on the children pseudo-attribute of the entry's parent.
The modify operation requires write (=w) privileges on the attributes
being modified. In detail, add (=a) is required to add new values,
delete (=z) is required to delete existing values, and both delete
and add (=az), or write (=w), are required to replace existing
values.
The modrdn operation requires write (=w) privileges on the pseudo-
attribute entry of the entry whose relative DN is being modified,
delete (=z) privileges on the pseudo-attribute children of the old
entry's parents, add (=a) privileges on the pseudo-attribute children
of the new entry's parents, and add (=a) privileges on the attributes
that are present in the new relative DN. Delete (=z) privileges are
also required on the attributes that are present in the old relative
DN if deleteoldrdn is set to 1.
The search operation, requires search (=s) privileges on the entry
pseudo-attribute of the searchBase (NOTE: this was introduced with
OpenLDAP 2.4). Then, for each entry, it requires search (=s)
privileges on the attributes that are defined in the filter. The
resulting entries are finally tested for read (=r) privileges on the
pseudo-attribute entry (for read access to the entry itself) and for
read (=r) access on each value of each attribute that is requested.
Also, for each referral object used in generating continuation
references, the operation requires read (=r) access on the pseudo-
attribute entry (for read access to the referral object itself), as
well as read (=r) access to the attribute holding the referral
information (generally the ref attribute).
Some internal operations and some controls require specific access
privileges. The authzID mapping and the proxyAuthz control require
auth (=x) privileges on all the attributes that are present in the
search filter of the URI regexp maps (the right-hand side of the
authz-regexp directives). Auth (=x) privileges are also required on
the authzTo attribute of the authorizing identity and/or on the
authzFrom attribute of the authorized identity. In general, when an
internal lookup is performed for authentication or authorization
purposes, search-specific privileges (see the access requirements for
the search operation illustrated above) are relaxed to auth.
Access control to search entries is checked by the frontend, so it is
fully honored by all backends; for all other operations and for the
discovery phase of the search operation, full ACL semantics is only
supported by the primary backends, i.e. back-bdb(5), and
back-hdb(5).
Some other backend, like back-sql(5), may fully support them; others
may only support a portion of the described semantics, or even differ
in some aspects. The relevant details are described in the backend-
specific man pages.
It is strongly recommended to explicitly use the most appropriate
<dnstyle> in <what> and <who> clauses, to avoid possible incorrect
specifications of the access rules as well as for performance (avoid
unnecessary regex matching when an exact match suffices) reasons.
An administrator might create a rule of the form:
access to dn.regex="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 ...
When writing submatch rules, it may be convenient to avoid
unnecessary regex <dnstyle> use; for instance, to allow access to the
subtree of the user that matches the <what> clause, one could use
access to dn.regex="^(.+,)?uid=([^,]+),dc=example,dc=com$"
by dn.regex="^uid=$2,dc=example,dc=com$$" write
by ...
However, since all that is required in the <by> clause is substring
expansion, a more efficient solution is
access to dn.regex="^(.+,)?uid=([^,]+),dc=example,dc=com$"
by dn.exact,expand="uid=$2,dc=example,dc=com" write
by ...
In fact, while a <dnstyle> of regex implies substring expansion,
exact, as well as all the other DN specific <dnstyle> values, does
not, so it must be explicitly requested.
ETCDIR/slapd.conf
default slapd configuration file
slapd(8), slapd-*(5), slapacl(8), regex(7), re_format(7)
"OpenLDAP Administrator's Guide" (http://www.OpenLDAP.org/doc/admin/)
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OpenLDAP LDVERSION RELEASEDATE SLAPD.ACCESS(5)
Pages that refer to this page: slapd-asyncmeta(5), slapd-bdb(5), slapd.conf(5), slapd-config(5), slapd-dnssrv(5), slapd-ldap(5), slapd-ldif(5), slapd-mdb(5), slapd-meta(5), slapd-monitor(5), slapd-ndb(5), slapd-null(5), slapd-passwd(5), slapd-perl(5), slapd-relay(5), slapd-shell(5), slapd-sock(5), slapd-sql(5), slapd-wt(5), slapo-dds(5), slapo-ppolicy(5), slapacl(8), slapd(8)
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