EnableSearchForAllUsers has been edited by Christine Koppelt (Sep 09, 2007).

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Enable Authenticated Users to Browse and Read Entries in a Subtree

The first time is always the hardest!

We presume this is your first encounter and so many bases will be covered this time around. Every other trail will build on this information. So expect a little less to read as you gain momentum.

Since the entire directory is locked down for all but the superuser, you're going to want to grant read and browse access to users for certain regions of the DIT. This will probably be the first thing you'll want to do after turning on access controls.

Check for insufficientAccessRights for Normal Users

Just to make sure everything is locked down login as admin and create a new non-superuser. For more information on how to do this see Authentication. After creating the normal user make sure you cannot bind to dc=example,dc=com with access controls enabled. You should get an error trying to bind with a result code of 50 (insufficientAccessRights). If using JNDI to connect to the server you should get a NoPermissionException. After we apply the following ACI you can check again.

Partition and Access Control Area Setup

For this example we presume you have setup a partition at the namingContext dc=example,dc=com and have turned on access controls. Now you want to grant browse and read access to entries and their attributes.

Before you can add a subentry with the prescriptiveACI you'll need to create an administrative area. For now we'll make the root of the partition the adminstrative point (AP). Every entry including this entry and those underneath it will be part of the autonous administrative area for managing access controls. To do this we must add the administrativeRole operational attribute to the AP entry. See ACArea for code and information about creating access control administrative areas.

Adding the Subentry

The subentry can be added using an LDIF or via code. We'll show the code but the LDIF can be accessed here enableSearchForAllUsers.ldif:

// Get a DirContext on the dc=example,dc=com entry
  Hashtable env = new Hashtable();
  env.put( "java.naming.factory.initial", "com.sun.jndi.ldap.LdapCtxFactory" );
  env.put( "java.naming.provider.url", "ldap://localhost:" + port + "/dc=example,dc=com" );
  env.put( "java.naming.security.principal", "uid=admin,ou=system" );
  env.put( "java.naming.security.credentials", "secret" );
  env.put( "java.naming.security.authentication", "simple" );
  ctx = new InitialDirContext( env );

  // now add the A/C subentry below dc=example,dc=com
  Attributes subentry = new BasicAttributes( "cn", "enableSearchForAllUsers", true );
  Attribute objectClass = new BasicAttribute( "objectClass" );
  subentry.put( objectClass );
  objectClass.add( "top" );
  objectClass.add( "subentry" );
  objectClass.add( "accessControlSubentry" );
  subentry.put( "subtreeSpecification", "{}" );
  subentry.put( "prescriptiveACI",
                "{ \n" +
                "  identificationTag \"enableSearchForAllUsers\",\n" +
                "  precedence 14,\n" +
                "  authenticationLevel simple,\n" +
                "  itemOrUserFirst userFirst: \n" +
                "  { \n" +
                "    userClasses { allUsers }, \n" +
                "    userPermissions \n" +
                "    { \n" +
                "      {\n" +
                "        protectedItems {entry, allUserAttributeTypesAndValues}, \n" +
                "        grantsAndDenials { grantRead, grantReturnDN, grantBrowse } \n" +
                "      }\n" +
                "    } \n" +
                "  } \n" +
                "}" );
  ctx.createSubcontext( "cn=enableSearchForAllUsers", subentry );

Before we cover the anatomy of this ACIItem, you might want to add the subentry and test access with a normal non-super user to make sure access is now granted.

ACIItem Description

Here's the ACIItem you just added above without all the Java clutter:

{ 
  identificationTag "enableSearchForAllUsers",
  precedence 14,
  authenticationLevel simple,
  itemOrUserFirst userFirst: 
  { 
    userClasses { allUsers }, 
    userPermissions 
    { 
       {
         protectedItems {entry, allUserAttributeTypesAndValues}, 
         grantsAndDenials { grantRead, grantReturnDN, grantBrowse } 
       }
    } 
  } 
}

There are several parameters to this simple ACIItem. Here's a breif exaplanation of each field and it's meaning or significance.

Fields Description
identificationTag Identifies the ACIItem within an entry.
precedence Determine which ACI to apply with conflicting ACIItems.
authenticationLevel User's level of trust with values of none, simple, strong
itemOrUserFirst Determines order of item permissions or user permissions.
userClasses The set of users the permissions apply to.
userPermissions Permissions on protected items

identificationTag

The identificationTag is just that a tag. It's often used with a subtring search filter to lookup a specific ACIItem within an entry. One or more ACIItems may be present within a subentry, zero or more in entries, so this serves as a means to address the ACIItem within entries.

precedence

Precendence is used to determine the ACI to apply when two or more ACIItem's applied to an entry conflict. The ACIItem with the highest precedence is applied over other conflicting ACIItems.

Denials Overpower Grants

When two or more conflicting ACIItems are encountered with the same precedence the ACIItems with denials overpower ACIItems with grants.

Right now the use of this field may not mean too much to you. We're dealing with a very simple situation with a single access control area. Later as you add more subentries their subtreeSpecifications may define collections that intersect. When this happens two or more conflicting ACIItems may apply to the same entry. Precendence is then applied to determine which permissions apply.

Another complex situation requiring precedence is the use of inner areas. These nested inner administrative areas overlap and so do their effects. The authority within an AA may deny some operation to all entries but grant access to subentries of inner areas so minor authorities can control access to inner areas. Their grants to users may need to have a higher precedence over denials in outer areas. Such situations will arise and precedence will need to be used. In this example we just assign an arbitrary value to the precedence.

authenticationLevel

The authenticationLevel is the minimum authentication requirement for requestor for the ACI to by applied: According to X.501:

18.4.2.3 Authentication Level

... Strong authentication of the requestor is considered to exceed a requirement for simple or no authentication, and simple authentication exceeds a requirement for no authentication ...

The authenticationLevel can have three values: none, simple and strong. It's used to be able to associate permissions with the level of trust in users. For none, the identity of the user is anonymous or does not matter. The user can be anyone. The simple authenticationLevel means the user has authenticated but is using a simple bind with clear text passwords. The strong authenticationLevel represents users that bind to the directory using strong authentication mechanisms via SASL.

SASL can allow annonynous binds as well so there is a distinction here. Using SASL alone does not mean the authenticationLevel is strong. As we add SASL mechanisms to the server, we'll qualify each one with none, simple or strong. This will be reflected in the authenticationLevel property of the principal making requests.

itemOrUserFirst

This field describes the order of information within the ACI whether protected items are described first or user classes and permissions are described first. For simplicity we will only describe the userFirst configuration in this tutorial.

userClasses

UserClasses is used to list the sets of users to which this permission applies. Several mechanisms can be used here to define userClasses. They can be defined by name per user, by group membership, or by the superset of all users possible and many more. In our example we have applied the ACI to all users that have authenticated by simple or strong means.

For more information see UserClasses.

userPermissions

These are the permissions granted or denied to those users included by the userClasses field. The grants or denials however are qualified by the protected items operated upon. In our example we grant read, return DN and browse to all entries, their attributes and all possible values they may have.

For more information see UserPermissions.

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