slapdconfig.sdf

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or {{EX:children}}.  Where {{EX:base}} matches only the entry with
provided DN, {{EX:one}} matches the entries whose parent is the
provided DN, {{EX:subtree}} matches all entries in the subtree whose
root is the provided DN, and {{EX:children}} matches all entries
under the DN (but not the entry named by the DN).

For example, if the directory contained entries named:

>	0: o=suffix
>	1: cn=Manager,o=suffix
>	2: ou=people,o=suffix
>	3: uid=kdz,ou=people,o=suffix
>	4: cn=addresses,uid=kdz,ou=people,o=suffix
>	5: uid=hyc,ou=people,o=suffix

\Then:
. {{EX:dn.base="ou=people,o=suffix"}} match 2;
. {{EX:dn.one="ou=people,o=suffix"}} match 3, and 5;
. {{EX:dn.subtree="ou=people,o=suffix"}} match 2, 3, 4, and 5; and
. {{EX:dn.children="ou=people,o=suffix"}} match 3, 4, and 5.


Entries may also be selected using a filter:

>	to filter=<ldap filter>

where <ldap filter> is a string representation of an LDAP
search filter, as described in {{REF:RFC2254}}.  For example:

>	to filter=(objectClass=person)

Note that entries may be selected by both DN and filter by
including both qualifiers in the <what> clause.

>	to dn.one="ou=people,o=suffix" filter=(objectClass=person)

Attributes within an entry are selected by including a comma-separated
list of attribute names in the <what> selector:

>	attrs=<attribute list>

A specific value of an attribute is selected by using a single
attribute name and also using a value selector:

>	attrs=<attribute> val[.<style>]=<regex>

There are two special {{pseudo}} attributes {{EX:entry}} and
{{EX:children}}.  To read (and hence return) a target entry, the
subject must have {{EX:read}} access to the target's {{entry}}
attribute.  To add or delete an entry, the subject must have
{{EX:write}} access to the entry's {{EX:entry}} attribute AND must
have {{EX:write}} access to the entry's parent's {{EX:children}}
attribute.  To rename an entry, the subject must have {{EX:write}}
access to entry's {{EX:entry}} attribute AND have {{EX:write}}
access to both the old parent's and new parent's {{EX:children}}
attributes.  The complete examples at the end of this section should
help clear things up.

Lastly, there is a special entry selector {{EX:"*"}} that is used to
select any entry.  It is used when no other {{EX:<what>}}
selector has been provided.  It's equivalent to "{{EX:dn=.*}}"


H3: Who to grant access to

The <who> part identifies the entity or entities being granted
access. Note that access is granted to "entities" not "entries."
The following table summarizes entity specifiers:

!block table; align=Center; coltags="EX,N"; \
	title="Table 5.3: Access Entity Specifiers"
Specifier|Entities
*|All, including anonymous and authenticated users
anonymous|Anonymous (non-authenticated) users
users|Authenticated users
self|User associated with target entry
dn[.<basic-style>]=<regex>|Users matching a regular expression
dn.<scope-style>=<DN>|Users within scope of a DN
!endblock

The DN specifier behaves much like <what> clause DN specifiers.

Other control factors are also supported.  For example, a {{EX:<who>}}
can be restricted by an entry listed in a DN-valued attribute in
the entry to which the access applies:

>	dnattr=<dn-valued attribute name>

The dnattr specification is used to give access to an entry
whose DN is listed in an attribute of the entry (e.g., give
access to a group entry to whoever is listed as the owner of
the group entry).

Some factors may not be appropriate in all environments (or any).
For example, the domain factor relies on IP to domain name lookups.
As these can easily spoofed, the domain factor should not be avoided.


H3: The access to grant


The kind of <access> granted can be one of the following:


!block table; colaligns="LRL"; coltags="EX,EX,N"; align=Center; \
	title="Table 5.4: Access Levels"
Level	Privileges	Description
none	=0		no access
auth	=x		needed to bind
compare	=cx		needed to compare
search	=scx		needed to apply search filters
read	=rscx		needed to read search results
write	=wrscx		needed to modify/rename
!endblock

Each level implies all lower levels of access. So, for
example, granting someone {{EX:write}} access to an entry also
grants them {{EX:read}}, {{EX:search}}, {{EX:compare}}, and 
{{EX:auth}} access.  However, one may use the privileges specifier
to grant specific permissions.


H3: Access Control Evaluation

When evaluating whether some requester should be given access to
an entry and/or attribute, slapd compares the entry and/or attribute
to the {{EX:<what>}} selectors given in the configuration file.
For each entry, access controls provided in the database which holds
the entry (or the first database if not held in any database) apply
first, followed by the global access directives.  Within this
priority, access directives are examined in the order in which they
appear in the config file.  Slapd stops with the first {{EX:<what>}}
selector that matches the entry and/or attribute. The corresponding
access directive is the one slapd will use to evaluate access.

Next, slapd compares the entity requesting access to the {{EX:<who>}}
selectors within the access directive selected above in the order
in which they appear. It stops with the first {{EX:<who>}} selector
that matches the requester. This determines the access the entity
requesting access has to the entry and/or attribute.

Finally, slapd compares the access granted in the selected
{{EX:<access>}} clause to the access requested by the client. If
it allows greater or equal access, access is granted. Otherwise,
access is denied.

The order of evaluation of access directives makes their placement
in the configuration file important. If one access directive is
more specific than another in terms of the entries it selects, it
should appear first in the config file. Similarly, if one {{EX:<who>}}
selector is more specific than another it should come first in the
access directive. The access control examples given below should
help make this clear.



H3: Access Control Examples

The access control facility described above is quite powerful.  This
section shows some examples of its use for descriptive purposes.

A simple example:

>	access to * by * read

This access directive grants read access to everyone.

>	access to *
>		by self write
>		by anonymous auth
>		by * read

This directive allows the user to modify their entry, allows anonymous
to authentication against these entries, and allows all others to
read these entries.  Note that only the first {{EX:by <who>}} clause
which matches applies.  Hence, the anonymous users are granted
{{EX:auth}}, not {{EX:read}}.  The last clause could just as well
have been "{{EX:by users read}}".

It is often desirable to restrict operations based upon the level
of protection in place.  The following shows how security strength
factors (SSF) can be used.

>	access to *
>		by ssf=128 self write
>		by ssf=64 anonymous auth
>		by ssf=64 users read

This directive allows users to modify their own entries if security
protections have of strength 128 or better have been established,
allows authentication access to anonymous users, and read access
when 64 or better security protections have been established.  If
client has not establish sufficient security protections, the
implicit {{EX:by * none}} clause would be applied.

The following example shows the use of a style specifiers to select
the entries by DN in two access directives where ordering is
significant.

>	access to dn.children="dc=example,dc=com"
> 		by * search
>	access to dn.children="dc=com"
> 		by * read

Read access is granted to entries under the {{EX:dc=com}} subtree,
except for those entries under the {{EX:dc=example,dc=com}} subtree,
to which search access is granted.  No access is granted to
{{EX:dc=com}} as neither access directive matches this DN.  If the
order of these access directives was reversed, the trailing directive
would never be reached, since all entries under {{EX:dc=example,dc=com}}
are also under {{EX:dc=com}} entries.

Also note that if no {{EX:access to}} directive matches or no {{EX:by
<who>}} clause, {{B:access is denied}}.  That is, every {{EX:access
to}} directive ends with an implicit {{EX:by * none}} clause and
every access list ends with an implicit {{EX:access to * by * none}}
directive.

The next example again shows the importance of ordering, both of
the access directives and the {{EX:by <who>}} clauses.  It also
shows the use of an attribute selector to grant access to a specific
attribute and various {{EX:<who>}} selectors.

>	access to dn.subtree="dc=example,dc=com" attrs=homePhone
>		by self write
>		by dn.children="dc=example,dc=com" search
>		by peername.regex=IP:10\..+ read
>	access to dn.subtree="dc=example,dc=com"
>		by self write
>		by dn.children="dc=example,dc=com" search
>		by anonymous auth

This example applies to entries in the "{{EX:dc=example,dc=com}}"
subtree. To all attributes except {{EX:homePhone}}, an entry can
write to itself, entries under {{EX:example.com}} entries can search
by them, anybody else has no access (implicit {{EX:by * none}})
excepting for authentication/authorization (which is always done
anonymously).  The {{EX:homePhone}} attribute is writable by the
entry, searchable by entries under {{EX:example.com}}, readable by
clients connecting from network 10, and otherwise not readable
(implicit {{EX:by * none}}).  All other access is denied by the
implicit {{EX:access to * by * none}}.

Sometimes it is useful to permit a particular DN to add or
remove itself from an attribute. For example, if you would like to
create a group and allow people to add and remove only
their own DN from the member attribute, you could accomplish
it with an access directive like this:

>	access to attrs=member,entry
> 		by dnattr=member selfwrite

The dnattr {{EX:<who>}} selector says that the access applies to
entries listed in the {{EX:member}} attribute. The {{EX:selfwrite}} access
selector says that such members can only add or delete their
own DN from the attribute, not other values. The addition of
the entry attribute is required because access to the entry is
required to access any of the entry's attributes.

!if 0
For more details on how to use the {{EX:access}} directive,
consult the {{Advanced Access Control}} chapter.
!endif


H2: Configuration File Example

The following is an example configuration file, interspersed
with explanatory text. It defines two databases to handle
different parts of the {{TERM:X.500}} tree; both are {{TERM:BDB}}
database instances. The line numbers shown are provided for
reference only and are not included in the actual file. First, the
global configuration section:

E:  1.	# example config file - global configuration section
E:  2.	include /usr/local/etc/schema/core.schema
E:  3.	referral ldap://root.openldap.org
E:  4.	access to * by * read
 
Line 1 is a comment. Line 2 includes another config file
which contains {{core}} schema definitions.
The {{EX:referral}} directive on line 3
means that queries not local to one of the databases defined
below will be referred to the LDAP server running on the
standard port (389) at the host {{EX:root.openldap.org}}.

Line 4 is a global access control.  It applies to all
entries (after any applicable database-specific access
controls).

The next section of the configuration file defines a BDB
backend that will handle queries for things in the
"dc=example,dc=com" portion of the tree. The
database is to be replicated to two slave slapds, one on
truelies, the other on judgmentday. Indices are to be
maintained for several attributes, and the {{EX:userPassword}}
attribute is to be protected from unauthorized access.

E:  5.	# BDB definition for the example.com
E:  6.	database bdb
E:  7.	suffix "dc=example,dc=com"
E:  8.	directory /usr/local/var/openldap-data
E:  9.	rootdn "cn=Manager,dc=example,dc=com"
E: 10.	rootpw secret
E: 11.	# replication directives
E: 12.	replogfile /usr/local/var/openldap/slapd.replog
E: 13.	replica uri=ldap://slave1.example.com:389
E: 14.		binddn="cn=Replicator,dc=example,dc=com"
E: 15.		bindmethod=simple credentials=secret
E: 16.	replica uri=ldaps://slave2.example.com:636
E: 17.		binddn="cn=Replicator,dc=example,dc=com"
E: 18.		bindmethod=simple credentials=secret
E: 19.	# indexed attribute definitions
E: 20.	index uid pres,eq
E: 21.	index cn,sn,uid pres,eq,approx,sub
E: 22.	index objectClass eq
E: 23.	# database access control definitions
E: 24.	access to attrs=userPassword
E: 25.		by self write
E: 26.		by anonymous auth
E: 27.		by dn.base="cn=Admin,dc=example,dc=com" write
E: 28.		by * none
E: 29.	access to *
E: 30.		by self write
E: 31.		by dn.base="cn=Admin,dc=example,dc=com" write
E: 32.		by * read

Line 5 is a comment. The start of the database definition is marked
by the database keyword on line 6. Line 7 specifies the DN suffix
for queries to pass to this database. Line 8 specifies the directory
in which the database files will live.

Lines 9 and 10 identify the database {{super-user}} entry and associated
password. This entry is not subject to access control or size or
time limit restrictions.

Lines 11 through 18 are for replication. Line 12 specifies the
replication log file (where changes to the database are logged -
this file is written by slapd and read by slurpd). Lines 13 through
15 specify the hostname and port for a replicated host, the DN to
bind as when performing updates, the bind method (simple) and the
credentials (password) for the binddn. Lines 16 through 18 specify
a second replication site.  See the {{SECT:Replication with slurpd}}
chapter for more information on these directives.

Lines 20 through 22 indicate the indices to maintain for various
attributes.

Lines 24 through 32 specify access control for entries in this
database.  As this is the first database, the controls also apply
to entries not held in any database (such as the Root DSE).  For
all applicable entries, the {{EX:userPassword}} attribute is writable
by the entry itself and by the "admin" entry.  It may be used for
authentication/authorization purposes, but is otherwise not readable.
All other attributes are writable by the entry and the "admin"
entry, but may be read by all users (authenticated or not).

The next section of the example configuration file defines another
BDB database. This one handles queries involving the
{{EX:dc=example,dc=net}} subtree but is managed by the same entity
as the first database.  Note that without line 39, the read access
would be allowed due to the global access rule at line 4.

E: 33.	# BDB definition for example.net
E: 34.	database bdb
E: 35.	suffix "dc=example,dc=net"
E: 36.	directory /usr/local/var/openldap-data-net
E: 37.	rootdn "cn=Manager,dc=example,dc=com"
E: 38.	index objectClass eq
E: 39.	access to * by users read