--- 1/draft-ietf-ldapbis-protocol-22.txt 2006-02-05 00:12:21.000000000 +0100 +++ 2/draft-ietf-ldapbis-protocol-23.txt 2006-02-05 00:12:21.000000000 +0100 @@ -1,14 +1,14 @@ Internet-Draft Editor: J. Sermersheim Intended Category: Standard Track Novell, Inc -Document: draft-ietf-ldapbis-protocol-22.txt Feb 2004 +Document: draft-ietf-ldapbis-protocol-23.txt Apr 2004 Obsoletes: RFC 2251, 2830, [LIMR] LDAP: The Protocol Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. Internet-Drafts are working documents of the Internet Engineering @@ -37,82 +37,80 @@ (LDAP). LDAP provides access to distributed directory services that act in accordance with X.500 data and service models. These protocol elements are based on those described in the X.500 Directory Access Protocol (DAP). Table of Contents 1. Introduction....................................................2 1.1. Relationship to Obsolete Specifications.......................3 2. Conventions.....................................................3 - 3. Protocol Model..................................................3 + 3. Protocol Model..................................................4 4. Elements of Protocol............................................4 - 4.1. Common Elements...............................................4 + 4.1. Common Elements...............................................5 4.1.1. Message Envelope............................................5 4.1.2. String Types................................................6 - -Sermersheim Internet-Draft - Expires Aug 2004 Page 1 Lightweight Directory Access Protocol Version 3 - 4.1.3. Distinguished Name and Relative Distinguished Name..........6 + 4.1.3. Distinguished Name and Relative Distinguished Name..........7 4.1.4. Attribute Descriptions......................................7 4.1.5. Attribute Value.............................................7 - 4.1.6. Attribute Value Assertion...................................7 + 4.1.6. Attribute Value Assertion...................................8 4.1.7. Attribute and PartialAttribute..............................8 4.1.8. Matching Rule Identifier....................................8 - 4.1.9. Result Message..............................................8 + 4.1.9. Result Message..............................................9 4.1.10. Referral..................................................10 - 4.1.11. Controls..................................................11 + 4.1.11. Controls..................................................12 4.2. Bind Operation...............................................13 4.3. Unbind Operation.............................................16 4.4. Unsolicited Notification.....................................16 4.5. Search Operation.............................................17 4.6. Modify Operation.............................................26 - 4.7. Add Operation................................................27 - 4.8. Delete Operation.............................................28 + 4.7. Add Operation................................................28 + 4.8. Delete Operation.............................................29 4.9. Modify DN Operation..........................................29 4.10. Compare Operation...........................................30 4.11. Abandon Operation...........................................31 - 4.12. Extended Operation..........................................31 + 4.12. Extended Operation..........................................32 4.13. IntermediateResponse Message................................33 - 4.13.1. Usage with LDAP ExtendedRequest and ExtendedResponse......33 + 4.13.1. Usage with LDAP ExtendedRequest and ExtendedResponse......34 4.13.2. Usage with LDAP Request Controls..........................34 4.14. StartTLS Operation..........................................34 - 5. Protocol Element Encodings and Transfer........................36 - 5.1. Protocol Encoding............................................37 - 5.2. Transfer Protocols...........................................37 + 5. Protocol Encoding, Connection, and Transfer....................37 + 5.1 Operation and Connection Relationship.........................37 + 5.2. Protocol Encoding............................................37 + 5.3. Transmission Control Protocol (TCP)..........................38 6. Security Considerations........................................38 7. Acknowledgements...............................................39 - 8. Normative References...........................................39 + 8. Normative References...........................................40 9. Informative References.........................................41 10. IANA Considerations...........................................41 - 11. Editor's Address..............................................41 - Appendix A - LDAP Result Codes....................................42 - A.1 Non-Error Result Codes........................................42 - A.2 Result Codes..................................................42 - Appendix B - Complete ASN.1 Definition............................46 - Appendix C - Changes..............................................52 - C.1 Changes made to made to RFC 2251:.............................52 - C.2 Changes made to made to RFC 2830:.............................57 - C.3 Changes made to made to [LIMR]:...............................58 + 11. Editor's Address..............................................42 + Appendix A - LDAP Result Codes....................................43 + A.1 Non-Error Result Codes........................................43 + A.2 Result Codes..................................................43 + Appendix B - Complete ASN.1 Definition............................48 + Appendix C - Changes..............................................54 + C.1 Changes made to RFC 2251:.....................................54 + C.2 Changes made to RFC 2830:.....................................59 + C.3 Changes made to [LIMR]:.......................................60 1. Introduction The Directory is "a collection of open systems cooperating to provide directory services" [X.500]. A directory user, which may be a human or other entity, accesses the Directory through a client (or Directory User Agent (DUA)). The client, on behalf of the directory user, interacts with one or more servers (or Directory System Agents (DSA)). Clients interact with servers using a directory access protocol. -Sermersheim Internet-Draft - Expires Aug 2004 Page 2 Lightweight Directory Access Protocol Version 3 This document details the protocol elements of the Lightweight Directory Access Protocol (LDAP), along with their semantics. Following the description of protocol elements, it describes the way in which the protocol elements are encoded and transferred. 1.1. Relationship to Obsolete Specifications This document is an integral part of the LDAP Technical Specification @@ -137,39 +135,49 @@ <> 2. Conventions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", and "MAY" in this document are to be interpreted as described in [Keyword]. - The terms "connection" and "LDAP connection" both refer to the - underlying transport protocol connection between two protocol peers. + The term "stream" refers to the underlying transport service used to + carry the protocol exchange. - The term "TLS connection" refers to a [TLS]-protected LDAP - connection. + The term "connection" refers to application layer where LDAP PDUs are + exchanged between protocol peers. - The terms "association" and "LDAP association" both refer to the - association of the LDAP connection and its current authentication and - authorization state. + The term "TLS layer" refers to a layer inserted between the stream + and the connection that utilizes [TLS] to protect the exchange of + LDAP PDUs. + + The term "SASL layer" refers to a layer inserted between the stream + and the connection that utilizes [SASL] to protect the exchange of + LDAP PDUs. + + See the table in Section 5 for an illustration of these four terms. + + Lightweight Directory Access Protocol Version 3 + + The term "TLS-protected connection" refers to a connection protected + by a TLS-layer. + + The term "association" refers to the association of the connection + and its current authentication and authorization state. 3. Protocol Model The general model adopted by this protocol is one of clients performing protocol operations against servers. In this model, a client transmits a protocol request describing the operation to be - -Sermersheim Internet-Draft - Expires Aug 2004 Page 3 - Lightweight Directory Access Protocol Version 3 - performed to a server. The server is then responsible for performing the necessary operation(s) in the Directory. Upon completion of an operation, the server typically returns a response containing appropriate data to the requesting client. Although servers are required to return responses whenever such responses are defined in the protocol, there is no requirement for synchronous behavior on the part of either clients or servers. Requests and responses for multiple operations generally may be exchanged between a client and server in any order, provided the @@ -180,50 +188,49 @@ to a subset of the X.500 (1993) Directory Abstract Service [X.511]. However there is not a one-to-one mapping between LDAP operations and X.500 Directory Access Protocol (DAP) operations. Server implementations acting as a gateway to X.500 directories may need to make multiple DAP requests to service a single LDAP request. 4. Elements of Protocol The protocol is described using Abstract Syntax Notation One ([ASN.1]), and is transferred using a subset of ASN.1 Basic Encoding - Rules ([BER]). Section 5.1 specifies how the protocol elements are + Rules ([BER]). Section 5 specifies how the protocol elements are encoded and transferred. In order to support future extensions to this protocol, extensibility is implied where it is allowed per ASN.1 (i.e. sequence, set, choice, and enumerated types are extensible). In addition, ellipses (...) have been supplied in ASN.1 types that are explicitly extensible as discussed in [LDAPIANA]. Because of the implied extensibility, clients and servers MUST (unless otherwise specified) ignore trailing SEQUENCE components whose tags they do not recognize. Changes to the protocol other than through the extension mechanisms described here require a different version number. A client indicates the version it is using as part of the bind request, described in Section 4.2. If a client has not sent a bind, the server MUST assume the client is using version 3 or later. + Lightweight Directory Access Protocol Version 3 + Clients may determine the protocol versions a server supports by reading the 'supportedLDAPVersion' attribute from the root DSE (DSA- Specific Entry) [Models]. 4.1. Common Elements This section describes the LDAPMessage envelope Protocol Data Unit (PDU) format, as well as data type definitions, which are used in the protocol operations. -Sermersheim Internet-Draft - Expires Aug 2004 Page 4 - Lightweight Directory Access Protocol Version 3 - 4.1.1. Message Envelope For the purposes of protocol exchanges, all protocol operations are encapsulated in a common envelope, the LDAPMessage, which is defined as follows: LDAPMessage ::= SEQUENCE { messageID MessageID, protocolOp CHOICE { bindRequest BindRequest, @@ -253,35 +260,33 @@ MessageID ::= INTEGER (0 .. maxInt) maxInt INTEGER ::= 2147483647 -- (2^^31 - 1) -- The ASN.1 type Controls is defined in Section 4.1.11. The function of the LDAPMessage is to provide an envelope containing common fields required in all protocol exchanges. At this time the only common fields are the message ID and the controls. + Lightweight Directory Access Protocol Version 3 + If the server receives a PDU from the client in which the LDAPMessage SEQUENCE tag cannot be recognized, the messageID cannot be parsed, the tag of the protocolOp is not recognized as a request, or the encoding structures or lengths of data fields are found to be incorrect, then the server SHOULD return the Notice of Disconnection described in Section 4.4.1, with the resultCode set to protocolError, - and MUST immediately close the connection. + and MUST immediately close the stream. In other cases where the client or server cannot parse a PDU, it - SHOULD abruptly close the connection where further communication + SHOULD abruptly close the stream where further communication (including providing notice) would be pernicious. Otherwise, server - -Sermersheim Internet-Draft - Expires Aug 2004 Page 5 - Lightweight Directory Access Protocol Version 3 - implementations MUST return an appropriate response to the request, with the resultCode set to protocolError. 4.1.1.1. Message ID All LDAPMessage envelopes encapsulating responses contain the messageID value of the corresponding request LDAPMessage. The message ID of a request MUST have a non-zero value different from the values of any other requests outstanding in the LDAP association @@ -309,34 +314,33 @@ LDAPString ::= OCTET STRING -- UTF-8 encoded, -- [ISO10646] characters The LDAPOID is a notational convenience to indicate that the permitted value of this string is a (UTF-8 encoded) dotted-decimal representation of an OBJECT IDENTIFIER. Although an LDAPOID is encoded as an OCTET STRING, values are limited to the definition of given in Section 1.4 of [Models]. + Lightweight Directory Access Protocol Version 3 + LDAPOID ::= OCTET STRING -- Constrained to [Models] For example, 1.3.6.1.4.1.1466.1.2.3 4.1.3. Distinguished Name and Relative Distinguished Name An LDAPDN is defined to be the representation of a Distinguished Name (DN) after encoding according to the specification in [LDAPDN]. -Sermersheim Internet-Draft - Expires Aug 2004 Page 6 - Lightweight Directory Access Protocol Version 3 - LDAPDN ::= LDAPString -- Constrained to [LDAPDN] A RelativeLDAPDN is defined to be the representation of a Relative Distinguished Name (RDN) after encoding according to the specification in [LDAPDN]. RelativeLDAPDN ::= LDAPString -- Constrained to [LDAPDN] @@ -362,35 +366,33 @@ AttributeValue ::= OCTET STRING Note that there is no defined limit on the size of this encoding; thus protocol values may include multi-megabyte attribute values (e.g. photographs). Attribute values may be defined which have arbitrary and non- printable syntax. Implementations MUST NOT display nor attempt to decode an attribute value if its syntax is not known. The implementation may attempt to discover the subschema of the source + Lightweight Directory Access Protocol Version 3 + entry, and retrieve the descriptions of 'attributeTypes' from it [Models]. Clients MUST only send attribute values in a request that are valid according to the syntax defined for the attributes. 4.1.6. Attribute Value Assertion The AttributeValueAssertion (AVA) type definition is similar to the one in the X.500 Directory standards. It contains an attribute description and a matching rule ([Models Section 4.1.3) assertion - -Sermersheim Internet-Draft - Expires Aug 2004 Page 7 - Lightweight Directory Access Protocol Version 3 - value suitable for that type. Elements of this type are typically used to assert that the value in assertionValue matches a value of an attribute. AttributeValueAssertion ::= SEQUENCE { attributeDesc AttributeDescription, assertionValue AssertionValue } AssertionValue ::= OCTET STRING @@ -409,42 +411,40 @@ Attribute requires at least one value. PartialAttribute ::= SEQUENCE { type AttributeDescription, vals SET OF value AttributeValue } Attribute ::= PartialAttribute(WITH COMPONENTS { ..., vals (SIZE(1..MAX))}) - No two attribute values are equivalent as described by Section 2.3 of - [Models]. The set of attribute values is unordered. Implementations - MUST NOT rely upon the ordering being repeatable. + No two attribute values may be equivalent as described by Section 2.3 + of [Models]. The set of attribute values is unordered. + Implementations MUST NOT rely upon the ordering being repeatable. 4.1.8. Matching Rule Identifier Matching rules are defined in Section 4.1.3 of [Models]. A matching rule is identified in the protocol by the printable representation of + Lightweight Directory Access Protocol Version 3 + either its , or one of its short name descriptors [Models], e.g. 'caseIgnoreMatch' or '2.5.13.2'. MatchingRuleId ::= LDAPString 4.1.9. Result Message The LDAPResult is the construct used in this protocol to return success or failure indications from servers to clients. To various requests, servers will return responses of LDAPResult or responses - -Sermersheim Internet-Draft - Expires Aug 2004 Page 8 - Lightweight Directory Access Protocol Version 3 - containing the components of LDAPResult to indicate the final status of a protocol operation request. LDAPResult ::= SEQUENCE { resultCode ENUMERATED { success (0), operationsError (1), protocolError (2), timeLimitExceeded (3), sizeLimitExceeded (4), @@ -474,35 +474,33 @@ inappropriateAuthentication (48), invalidCredentials (49), insufficientAccessRights (50), busy (51), unavailable (52), unwillingToPerform (53), loopDetect (54), -- 55-63 unused -- namingViolation (64), objectClassViolation (65), + Lightweight Directory Access Protocol Version 3 + notAllowedOnNonLeaf (66), notAllowedOnRDN (67), entryAlreadyExists (68), objectClassModsProhibited (69), -- 70 reserved for CLDAP -- affectsMultipleDSAs (71), -- 72-79 unused -- other (80), ... }, matchedDN LDAPDN, diagnosticMessage LDAPString, - -Sermersheim Internet-Draft - Expires Aug 2004 Page 9 - Lightweight Directory Access Protocol Version 3 - referral [3] Referral OPTIONAL } The resultCode enumeration is extensible as defined in Section 3.6 of [LDAPIANA]. The meanings of the listed result codes are given in Appendix A. If a server detects multiple errors for an operation, only one result code is returned. The server should return the result code that best indicates the nature of the error encountered. The diagnosticMessage field of this construct may, at the server's option, be used to return a string containing a textual, human- @@ -516,48 +514,56 @@ noSuchObject, aliasProblem, invalidDNSyntax and aliasDereferencingProblem), the matchedDN field is set to the name of the lowest entry (object or alias) in the Directory that was matched. If no aliases were dereferenced while attempting to locate the entry, this will be a truncated form of the name provided, or if aliases were dereferenced, of the resulting name, as defined in Section 12.5 of [X.511]. Otherwise the matchedDN field is empty. 4.1.10. Referral - The referral result code indicates that the contacted server does not - hold the target entry of the request. The referral field is present - in an LDAPResult if the resultCode field value is referral, and - absent with all other result codes. It contains one or more - references to one or more servers or services that may be accessed - via LDAP or other protocols. Referrals can be returned in response to - any operation request (except unbind and abandon which do not have - responses). At least one URI MUST be present in the Referral. + The referral result code indicates that the contacted server cannot + or will not perform the operation and that one or more other servers + may be able to. Reasons for this include: + + - The target entry of the request is not held locally, but the + server has knowledge of its possible existence elsewhere. + + - The operation is restricted on this server -- perhaps due to a + read-only copy of an entry to be modified. + + The referral field is present in an LDAPResult if the resultCode + field value is referral, and absent with all other result codes. It + contains one or more references to one or more servers or services + that may be accessed via LDAP or other protocols. Referrals can be + returned in response to any operation request (except unbind and + Lightweight Directory Access Protocol Version 3 + + abandon which do not have responses). At least one URI MUST be + present in the Referral. During a search operation, after the baseObject is located, and entries are being evaluated, the referral is not returned. Instead, continuation references, described in Section 4.5.3, are returned when other servers would need to be contacted to complete the operation. Referral ::= SEQUENCE SIZE (1..MAX) OF uri URI URI ::= LDAPString -- limited to characters permitted in -- URIs If the client wishes to progress the operation, it MUST follow the referral by contacting one of the supported services. If multiple URIs are present, the client assumes that any supported URI may be used to progress the operation. -Sermersheim Internet-Draft - Expires Aug 2004 Page 10 - Lightweight Directory Access Protocol Version 3 - Protocol peers that follow referrals MUST ensure that they do not loop between servers. They MUST NOT repeatedly contact the same server for the same request with the same target entry name, scope and filter. Some implementations use a counter that is incremented each time referral handling occurs for an operation, and these kinds of implementations MUST be able to handle at least ten nested referrals between the root and a leaf entry. A URI for a server implementing LDAP and accessible via [TCP]/[IP] (v4 or v6) is written as an LDAP URL according to [LDAPURL]. @@ -562,36 +568,45 @@ A URI for a server implementing LDAP and accessible via [TCP]/[IP] (v4 or v6) is written as an LDAP URL according to [LDAPURL]. When an LDAP URL is used, the following instructions are followed: - If an alias was dereferenced, the part of the URL MUST be present, with the new target object name. UTF-8 encoded characters appearing in the string representation of a DN or search filter may not be legal for URLs (e.g. spaces) and MUST be escaped using the % method in [URI]. + - It is RECOMMENDED that the part be present to avoid ambiguity. + - If the part is present, the client MUST use this name in its next request to progress the operation, and if it is not present the client will use the same name as in the original request. + - Some servers (e.g. participating in distributed indexing) may provide a different filter in a URL of a referral for a search operation. + - If the part of the LDAP URL is present, the client MUST use this filter in its next request to progress this search, and if it is not present the client MUST use the same filter as it used for that search. + + Lightweight Directory Access Protocol Version 3 + - For search, it is RECOMMENDED that the part be present to avoid ambiguity. + - If the part is missing, the scope of the original search is used by the client to progress the operation. + - Other aspects of the new request may be the same as or different from the request which generated the referral. Other kinds of URIs may be returned. The syntax and semantics of such URIs is left to future specifications. Clients may ignore URIs that they do not support. 4.1.11. Controls Controls provide a mechanism whereby the semantics and arguments of @@ -594,87 +609,81 @@ 4.1.11. Controls Controls provide a mechanism whereby the semantics and arguments of existing LDAP operations may be extended. One or more controls may be attached to a single LDAP message. A control only affects the semantics of the message it is attached to. Controls sent by clients are termed 'request controls' and those sent by servers are termed 'response controls'. - When an extension calls for a particular response control to be sent - in response to a request control, the response and request controls - are termed to be "paired". - -Sermersheim Internet-Draft - Expires Aug 2004 Page 11 - Lightweight Directory Access Protocol Version 3 Controls ::= SEQUENCE OF control Control Control ::= SEQUENCE { controlType LDAPOID, criticality BOOLEAN DEFAULT FALSE, controlValue OCTET STRING OPTIONAL } The controlType field is the dotted-decimal representation of an - OBJECT IDENTIFIER which uniquely identifies the control, or the - request control and its paired response control. This provides - unambiguous naming of controls. + OBJECT IDENTIFIER which uniquely identifies the control. This + provides unambiguous naming of controls. Often, response control(s) + solicited by a request control share controlType values with the + request control. The criticality field only has meaning in controls attached to request messages (except unbindRequest). For controls attached to response messages and the unbindRequest, the criticality field SHOULD be FALSE, and MUST be ignored by the receiving protocol peer. A value of TRUE indicates that it is unacceptable to perform the operation without applying the semantics of the control and FALSE otherwise. Specifically, the criticality field is applied as follows: - Regardless of the value of the criticality field, if the server recognizes the control type and it is appropriate for the operation, the server is to make use of the control when performing the operation. - If the server does not recognize the control type or it is not appropriate for the operation, and the criticality field is TRUE, the server MUST NOT perform the operation, and for operations that + Lightweight Directory Access Protocol Version 3 + have a response message, MUST return unavailableCriticalExtension in the resultCode. - If the server does not recognize the control type or it is not appropriate for the operation, and the criticality field is FALSE, the server MUST ignore the control. The controlValue may contain information associated with the controlType. Its format is defined by the specification of the control. Implementations MUST be prepared to handle arbitrary contents of the controlValue octet string, including zero bytes. It is absent only if there is no value information which is associated with a control of its type. When a controlValue is defined in terms - of ASN.1, and BER encoded according to Section 5.1, it also follows + of ASN.1, and BER encoded according to Section 5.2, it also follows the extensibility rules in Section 4. Servers list the controlType of all request controls they recognize in the supportedControl attribute in the root DSE (Section 5.1 of [Models]). Controls SHOULD NOT be combined unless the semantics of the combination has been specified. The semantics of control combinations, if specified, are generally found in the control specification most recently published. In the absence of combination semantics, the behavior of the operation is undefined. - -Sermersheim Internet-Draft - Expires Aug 2004 Page 12 - Lightweight Directory Access Protocol Version 3 - Additionally, unless order-dependent semantics are given in a specification, the order of a combination of controls in the SEQUENCE - is ignored. + is ignored. Where the order is to be ignored but cannot be ignored by + the server, the operation fails with protocolError. This document does not specify any controls. Controls may be specified in other documents. Documents detailing control extensions are to provide for each control: - the OBJECT IDENTIFIER assigned to the control, - direction as to what value the sender should provide for the criticality field (note: the semantics of the criticality field are defined above should not be altered by the control's @@ -685,23 +694,25 @@ - the semantics of the control, and - optionally, semantics regarding the combination of the control with other controls. 4.2. Bind Operation The function of the Bind Operation is to allow authentication information to be exchanged between the client and server. The Bind + Lightweight Directory Access Protocol Version 3 + operation should be thought of as the "authenticate" operation. - Authentication and security-related semantics of this operation are - given in [AuthMeth]. + Operational, authentication, and security-related semantics of this + operation are given in [AuthMeth]. The Bind Request is defined as follows: BindRequest ::= [APPLICATION 0] SEQUENCE { version INTEGER (1 .. 127), name LDAPDN, authentication AuthenticationChoice } AuthenticationChoice ::= CHOICE { simple [0] OCTET STRING, @@ -711,199 +722,182 @@ SaslCredentials ::= SEQUENCE { mechanism LDAPString, credentials OCTET STRING OPTIONAL } Fields of the Bind Request are: - version: A version number indicating the version of the protocol to be used in this LDAP association. This document describes version 3 of the protocol. There is no version negotiation. The - -Sermersheim Internet-Draft - Expires Aug 2004 Page 13 - Lightweight Directory Access Protocol Version 3 - client sets this field to the version it desires. If the server does not support the specified version, it MUST respond with protocolError in the resultCode field of the BindResponse. - name: The name of the Directory object that the client wishes to bind as. This field may take on a null value (a zero length string) for the purposes of anonymous binds ([AuthMeth] Section 5.1) or when using Simple Authentication and Security Layer [SASL] - authentication ([AuthMeth] Section 3.3.2). Server behavior is - undefined when the name is a null value, simple authentication is - used, and a non-null password is specified. Where the server + authentication ([AuthMeth] Section 3.3.2). Where the server attempts to locate the named object, it SHALL NOT perform alias dereferencing. - authentication: information used in authentication. This type is extensible as defined in Section 3.7 of [LDAPIANA]. Servers that do not support a choice supplied by a client return authMethodNotSupported in the resultCode field of the BindResponse. Textual passwords (consisting of a character sequence with a known character set and encoding) transferred to the server using the simple AuthenticationChoice SHALL be transferred as [UTF-8] encoded [Unicode]. Prior to transfer, clients SHOULD prepare text passwords by applying the [SASLprep] profile of the [Stringprep] algorithm. Passwords consisting of other data (such as random octets) MUST NOT be altered. The determination of whether a password is textual is a local client matter. - Authorization is the use of this authentication information when - performing operations. Authorization MAY be affected by factors - outside of the LDAP Bind Request, such as those provided by lower - layer security services. + Lightweight Directory Access Protocol Version 3 + + Authorization is the process of enforcing policy while performing + operations. Among other things, the process of authorization takes as + input authentication information obtained during the bind operation + and/or other acts of authentication (such as lower layer security + services). 4.2.1. Processing of the Bind Request Before processing a BindRequest, all outstanding operations MUST either complete or be abandoned. The server may either wait for the outstanding operations to complete, or abandon them. The server then proceeds to authenticate the client in either a single-step, or multi-step bind process. Each step requires the server to return a BindResponse to indicate the status of authentication. If the client did not bind before sending a request and receives an operationsError to that request, it may then send a Bind Request. If this also fails or the client chooses not to bind on the existing - connection, it may close the connection, reopen it and begin again by + connection, it may close the stream, reopen it and begin again by first sending a PDU with a Bind Request. This will aid in interoperating with servers implementing other versions of LDAP. Clients may send multiple Bind Requests on a connection to change the authentication and/or security associations or to complete a multi- - -Sermersheim Internet-Draft - Expires Aug 2004 Page 14 - Lightweight Directory Access Protocol Version 3 - stage bind process. Authentication from earlier binds is subsequently ignored. For some SASL authentication mechanisms, it may be necessary for the - client to invoke the BindRequest multiple times. This is indicated by - the server sending a BindResponse with the resultCode set to - saslBindInProgress. This indicates that the server requires the - client to send a new bind request, with the same sasl mechanism, to - continue the authentication process. Clients MUST NOT invoke - operations between two Bind Requests made as part of a multi-stage - bind. + client to invoke the BindRequest multiple times ([AuthMeth] Section + 8.2). Clients MUST NOT invoke operations between two Bind Requests + made as part of a multi-stage bind. A client may abort a SASL bind negotiation by sending a BindRequest with a different value in the mechanism field of SaslCredentials, or an AuthenticationChoice other than sasl. If the client sends a BindRequest with the sasl mechanism field as an empty string, the server MUST return a BindResponse with authMethodNotSupported as the resultCode. This will allow clients to abort a negotiation if it wishes to try again with the same SASL mechanism. - A failed Bind Operation has the effect of placing the connection in - an anonymous state. - 4.2.2. Bind Response The Bind Response is defined as follows. BindResponse ::= [APPLICATION 1] SEQUENCE { COMPONENTS OF LDAPResult, serverSaslCreds [7] OCTET STRING OPTIONAL } BindResponse consists simply of an indication from the server of the status of the client's request for authentication. + Lightweight Directory Access Protocol Version 3 + A successful bind operation is indicated by a BindResponse with a resultCode set to success. Otherwise, an appropriate result code is set in the BindResponse. For bind, the protocolError result code may be used to indicate that the version number supplied by the client is unsupported. If the client receives a BindResponse where the resultCode field is protocolError, it is to assume that the server does not support this version of LDAP. While the client may be able proceed with another - version of this protocol (this may or may not require establishing a - new connection), how to proceed with another version of this protocol - is beyond the scope of this document. Clients which are unable or - unwilling to proceed SHOULD drop the underlying connection. + version of this protocol (this may or may not require closing and re- + establishing the stream), how to proceed with another version of this + protocol is beyond the scope of this document. Clients which are + unable or unwilling to proceed SHOULD close the underlying stream. The serverSaslCreds field is used as part of a SASL-defined bind mechanism to allow the client to authenticate the server to which it is communicating, or to perform "challenge-response" authentication. - -Sermersheim Internet-Draft - Expires Aug 2004 Page 15 - Lightweight Directory Access Protocol Version 3 - If the client bound with the simple choice, or the SASL mechanism does not require the server to return information to the client, then this field SHALL NOT be included in the BindResponse. 4.3. Unbind Operation The function of the Unbind Operation is to terminate an LDAP - association and connection. The Unbind operation is not the + association and close the stream. The Unbind operation is not the antithesis of the Bind operation as the name implies. The naming of these operations is historical. The Unbind operation should be thought of as the "quit" operation. The Unbind Operation is defined as follows: UnbindRequest ::= [APPLICATION 2] NULL The Unbind Operation has no response defined. Upon transmission of the UnbindRequest, each protocol peer is to consider the LDAP association terminated, MUST cease transmission of messages to the - other peer, and MUST close the connection. Outstanding operations are - handled as specified in Section 5.2. + other peer, and MUST close the stream. Outstanding operations are + handled as specified in Section 5.1. 4.4. Unsolicited Notification An unsolicited notification is an LDAPMessage sent from the server to the client which is not in response to any LDAPMessage received by the server. It is used to signal an extraordinary condition in the server or in the connection between the client and the server. The notification is of an advisory nature, and the server will not expect any response to be returned from the client. The unsolicited notification is structured as an LDAPMessage in which the messageID is zero and protocolOp is of the extendedResp form (See + Lightweight Directory Access Protocol Version 3 + Section 4.12). The responseName field of the ExtendedResponse always contains an LDAPOID which is unique for this notification. One unsolicited notification (Notice of Disconnection) is defined in this document. The specification of an unsolicited notification consists of: - the OBJECT IDENTIFIER assigned to the notification (to be specified in the responseName, - the format of the contents (if any) of the responseValue, - the circumstances which will cause the notification to be returned, and - the semantics of the operation. 4.4.1. Notice of Disconnection -Sermersheim Internet-Draft - Expires Aug 2004 Page 16 - Lightweight Directory Access Protocol Version 3 - This notification may be used by the server to advise the client that - the server is about to close the connection due to an error - condition. This notification is intended to assist clients in - distinguishing between an error condition and a transient network - failure. Note that this notification is not a response to an unbind - requested by the client. Outstanding operations are handled as - specified in Section 5.2. + the server is about to close the stream due to an error condition. + This notification is intended to assist clients in distinguishing + between an error condition and a transient network failure. Note that + this notification is not a response to an unbind requested by the + client. Outstanding operations are handled as specified in Section + 5.1. The responseName is 1.3.6.1.4.1.1466.20036, the response field is absent, and the resultCode is used to indicate the reason for the disconnection. The following result codes have these meanings when used in this notification: - protocolError: The server has received data from the client in which the LDAPMessage structure could not be parsed. @@ -913,57 +907,55 @@ unexpectedly failed or been compromised, or that the server now requires the client to authenticate using a strong(er) mechanism. - unavailable: This server will stop accepting new connections and operations on all existing connections, and be unavailable for an extended period of time. The client may make use of an alternative server. Upon transmission of the Notice of Disconnection, the server is to consider the LDAP association terminated, MUST cease transmission of - messages to the client, and MUST close the connection. + messages to the client, and MUST close the stream. 4.5. Search Operation + Lightweight Directory Access Protocol Version 3 The Search Operation is used to request a server to return, subject to access controls and other restrictions, a set of entries matching a complex search criterion. This can be used to read attributes from a single entry, from entries immediately subordinate to a particular entry, or a whole subtree of entries. 4.5.1. Search Request The Search Request is defined as follows: SearchRequest ::= [APPLICATION 3] SEQUENCE { baseObject LDAPDN, scope ENUMERATED { baseObject (0), singleLevel (1), wholeSubtree (2) }, derefAliases ENUMERATED { - -Sermersheim Internet-Draft - Expires Aug 2004 Page 17 - Lightweight Directory Access Protocol Version 3 - neverDerefAliases (0), derefInSearching (1), derefFindingBaseObj (2), derefAlways (3) }, sizeLimit INTEGER (0 .. maxInt), timeLimit INTEGER (0 .. maxInt), typesOnly BOOLEAN, filter Filter, attributes AttributeSelection } - AttributeSelection ::= SEQUENCE OF selection LDAPString - -- constrained to below + AttributeSelection ::= SEQUENCE OF selector LDAPString + -- The LDAPString is constrained to + -- below Filter ::= CHOICE { and [0] SET SIZE (1..MAX) OF filter Filter, or [1] SET SIZE (1..MAX) OF filter Filter, not [2] Filter, equalityMatch [3] AttributeValueAssertion, substrings [4] SubstringFilter, greaterOrEqual [5] AttributeValueAssertion, lessOrEqual [6] AttributeValueAssertion, present [7] AttributeDescription, @@ -972,43 +964,42 @@ SubstringFilter ::= SEQUENCE { type AttributeDescription, -- initial and final can occur at most once substrings SEQUENCE SIZE (1..MAX) OF substring CHOICE { initial [0] AssertionValue, any [1] AssertionValue, final [2] AssertionValue } } MatchingRuleAssertion ::= SEQUENCE { + Lightweight Directory Access Protocol Version 3 + matchingRule [1] MatchingRuleId OPTIONAL, type [2] AttributeDescription OPTIONAL, matchValue [3] AssertionValue, dnAttributes [4] BOOLEAN DEFAULT FALSE } Fields of the Search Request are: - baseObject: The name of the base object entry relative to which the search is to be performed. - scope: Specifies the scope of the search to be performed. The semantics (as described in [X.511]) of the possible values of this field are: baseObject: The scope is constrained to the entry named by baseObject. singleLevel: The scope is constrained to the immediate subordinates of the entry named by baseObject. -Sermersheim Internet-Draft - Expires Aug 2004 Page 18 - Lightweight Directory Access Protocol Version 3 - wholeSubtree: the scope is constrained to the entry named by the baseObject, and all its subordinates. - derefAliases: An indicator as to how alias entries (as defined in [Models]) are to be handled in searching. The semantics of the possible values of this field are: neverDerefAliases: Do not dereference aliases in searching or in locating the base object of the search. @@ -1028,44 +1019,42 @@ locating the base object of the search. Servers MUST detect looping while dereferencing aliases in order to prevent denial of service attacks of this nature. - sizeLimit: A size limit that restricts the maximum number of entries to be returned as a result of the search. A value of zero in this field indicates that no client-requested size limit restrictions are in effect for the search. Servers may also enforce a maximum number of entries to return. + Lightweight Directory Access Protocol Version 3 + - timeLimit: A time limit that restricts the maximum time (in seconds) allowed for a search. A value of zero in this field indicates that no client-requested time limit restrictions are in effect for the search. Servers may also enforce a maximum time limit for the search. - typesOnly: An indicator as to whether search results are to contain both attribute descriptions and values, or just attribute descriptions. Setting this field to TRUE causes only attribute descriptions (no values) to be returned. Setting this field to FALSE causes both attribute descriptions and values to be returned. - filter: A filter that defines the conditions that must be fulfilled in order for the search to match a given entry. The 'and', 'or' and 'not' choices can be used to form combinations of filters. At least one filter element MUST be present in an 'and' or 'or' choice. The others match against individual attribute values of entries in the scope of the search. - -Sermersheim Internet-Draft - Expires Aug 2004 Page 19 - Lightweight Directory Access Protocol Version 3 - (Implementor's note: the 'not' filter is an example of a tagged choice in an implicitly-tagged module. In BER this is treated as if the tag was explicit.) A server MUST evaluate filters according to the three-valued logic of X.511 (1993) Section 7.8.1. In summary, a filter is evaluated to either "TRUE", "FALSE" or "Undefined". If the filter evaluates to TRUE for a particular entry, then the attributes of that entry are returned as part of the search result (subject to any applicable access control restrictions). If the filter evaluates @@ -1086,20 +1075,23 @@ The matching rule for equalityMatch filter items is defined by the EQUALITY matching rule for the attribute type. There SHALL be at most one 'initial', and at most one 'final' in the 'substrings' of a SubstringFilter. If 'initial' is present, it SHALL be the first element of 'substrings'. If 'final' is present, it SHALL be the last element of 'substrings'. The matching rule for AssertionValues in a substrings filter item is defined by the SUBSTR matching rule for the attribute type. + + Lightweight Directory Access Protocol Version 3 + Note that the AssertionValue in a substrings filter item conforms to the assertion syntax of the EQUALITY matching rule for the attribute type rather than the assertion syntax of the SUBSTR matching rule for the attribute type. Conceptually, the entire SubstringFilter is converted into an assertion value of the substrings matching rule prior to applying the rule. The matching rule for the greaterOrEqual filter item is defined by the ORDERING and EQUALITY matching rules for the attribute type. @@ -1107,23 +1099,20 @@ the ORDERING matching rule for the attribute type. An approxMatch filter item evaluates to TRUE when there is a value of the attribute or subtype for which some locally-defined approximate matching algorithm (e.g. spelling variations, phonetic match, etc.) returns TRUE. If an item matches for equality, it also satisfies an approximate match. If approximate matching is not supported, this filter item should be treated as an equalityMatch. -Sermersheim Internet-Draft - Expires Aug 2004 Page 20 - Lightweight Directory Access Protocol Version 3 - An extensibleMatch filter item is evaluated as follows: If the matchingRule field is absent, the type field MUST be present, and an equality match is performed for that type. If the type field is absent and the matchingRule is present, the matchValue is compared against all attributes in an entry which support that matchingRule. The matchingRule determines the syntax for the assertion value. The filter item evaluates to TRUE if it matches with at least one attribute in the entry, @@ -1143,45 +1132,44 @@ at least one attribute in the distinguished name for which the filter item evaluates to TRUE. The dnAttributes field is present to alleviate the need for multiple versions of generic matching rules (such as word matching), where one applies to entries and another applies to entries and dn attributes as well. A filter item evaluates to Undefined when the server would not be able to determine whether the assertion value matches an entry. If an attribute description in an equalityMatch, substrings, greaterOrEqual, lessOrEqual, approxMatch or extensibleMatch filter + Lightweight Directory Access Protocol Version 3 + is not recognized by the server, a matching rule id in the extensibleMatch is not recognized by the server, the assertion value is invalid, or the type of filtering requested is not implemented, then the filter is Undefined. Thus for example if a server did not recognize the attribute type shoeSize, a filter of (shoeSize=*) would evaluate to FALSE, and the filters (shoeSize=12), (shoeSize>=12) and (shoeSize<=12) would evaluate to Undefined. Servers MUST NOT return errors if attribute descriptions or matching rule ids are not recognized, assertion values are invalid, or the assertion syntax is not supported. More details of filter processing are given in Section 7.8 of [X.511]. - - attributes: A list of the attributes to be returned from each - entry which matches the search filter. LDAPString values of this - field are constrained to the following Augmented Backus-Naur Form - ([ABNF]): - - attributeSelection = attributedescription / selectionspecial + - attributes: A selection list of the attributes to be returned from + each entry which matches the search filter. LDAPString values of + this field are constrained to the following Augmented Backus-Naur + Form ([ABNF]): -Sermersheim Internet-Draft - Expires Aug 2004 Page 21 - Lightweight Directory Access Protocol Version 3 + attributeSelector = attributedescription / selectorpecial - selectionspecial = noattrs / alluserattrs + selectorspecial = noattrs / alluserattrs noattrs = %x31.2E.31 ; "1.1" alluserattrs = %x2A ; asterisk ("*") The production is defined in Section 2.5 of [Models]. There are three special cases which may exist in the attribute selection: @@ -1197,43 +1188,42 @@ A list containing only the OID "1.1" indicates that no values are to be returned. If "1.1" is provided with other values, the "1.1" value is ignored. This OID was chosen because it does not (and can not) correspond to any attribute in use. Client implementors should note that even if all user attributes are requested, some attributes and/or attribute values of the entry may not be included in search results due to access controls or other restrictions. Furthermore, servers will not return + Lightweight Directory Access Protocol Version 3 + operational attributes, such as objectClasses or attributeTypes, unless they are listed by name. Operational attributes are described in [Models]. Attributes are returned at most once in an entry. If an attribute description is named more than once in the list, the subsequent names are ignored. If an attribute description in the list is not recognized, it is ignored by the server. Note that an X.500 "list"-like operation can be emulated by the client requesting a one-level LDAP search operation with a filter checking for the presence of the 'objectClass' attribute, and that an X.500 "read"-like operation can be emulated by a base object LDAP search operation with the same filter. A server which provides a gateway to X.500 is not required to use the Read or List operations, although it may choose to do so, and if it does, it must provide the same semantics as the X.500 search operation. 4.5.2. Search Result -Sermersheim Internet-Draft - Expires Aug 2004 Page 22 - Lightweight Directory Access Protocol Version 3 - The results of the search operation are returned as zero or more searchResultEntry messages, zero or more SearchResultReference messages, followed by a single searchResultDone message. SearchResultEntry ::= [APPLICATION 4] SEQUENCE { objectName LDAPDN, attributes PartialAttributeList } PartialAttributeList ::= SEQUENCE OF partialAttribute PartialAttribute @@ -1252,20 +1242,22 @@ Each SearchResultEntry represents an entry found during the search. Each SearchResultReference represents an area not yet explored during the search. The SearchResultEntry and SearchResultReference PDUs may come in any order. Following all the SearchResultReference and SearchResultEntry responses, the server returns a SearchResultDone response, which contains an indication of success, or detailing any errors that have occurred. Each entry returned in a SearchResultEntry will contain all appropriate attributes as specified in the attributes field of the + Lightweight Directory Access Protocol Version 3 + Search Request. Return of attributes is subject to access control and other administrative policy. Some attributes may be constructed by the server and appear in a SearchResultEntry attribute list, although they are not stored attributes of an entry. Clients SHOULD NOT assume that all attributes can be modified, even if permitted by access control. If the server's schema defines short names [Models] for an attribute type then the server SHOULD use one of those names in attribute @@ -1273,29 +1265,26 @@ [Models] format of the attribute type's object identifier). The server SHOULD NOT use the short name if that name is known by the server to be ambiguous, or otherwise likely to cause interoperability problems. 4.5.3. Continuation References in the Search Result If the server was able to locate the entry referred to by the baseObject but was unable to search one or more non-local entries, the server may return one or more SearchResultReference entries, each - -Sermersheim Internet-Draft - Expires Aug 2004 Page 23 - Lightweight Directory Access Protocol Version 3 - containing a reference to another set of servers for continuing the operation. A server MUST NOT return any SearchResultReference if it has not located the baseObject and thus has not searched any entries; - in this case it would return a SearchResultDone containing a referral - result code. + in this case it would return a SearchResultDone containing either a + referral or noSuchObject result code (depending on the server's + knowledge of the entry named in the baseObject). If a server holds a copy or partial copy of the subordinate naming context [Section 5 of Models], it may use the search filter to determine whether or not to return a SearchResultReference response. Otherwise SearchResultReference responses are always returned when in scope. The SearchResultReference is of the same data type as the Referral. A URI for a server implementing LDAP and accessible via [TCP]/[IP] @@ -1309,46 +1298,51 @@ wishes to individually. Clients that follow search continuation references MUST ensure that they do not loop between servers. They MUST NOT repeatedly contact the same server for the same request with the same target entry name, scope and filter. Some clients use a counter that is incremented each time search result reference handling occurs for an operation, and these kinds of clients MUST be able to handle at least ten nested search result references between the root and a leaf entry. + Lightweight Directory Access Protocol Version 3 + When an LDAP URL is used, the following instructions are followed: - The part of the URL MUST be present, with the new target object name. The client MUST use this name when following the reference. UTF-8 encoded characters appearing in the string representation of a DN or search filter may not be legal for URLs (e.g. spaces) and MUST be escaped using the % method in [URI]. + - Some servers (e.g. participating in distributed indexing) may provide a different filter in a URL of a SearchResultReference. + - If the part of the URL is present, the client MUST use this filter in its next request to progress this search, and if it is not present the client MUST use the same filter as it used for that search. + - If the originating search scope was singleLevel, the part of the URL will be "base". + - it is RECOMMENDED that the part be present to avoid ambiguity. + - Other aspects of the new search request may be the same as or different from the search request which generated the SearchResultReference. + - The name of an unexplored subtree in a SearchResultReference need not be subordinate to the base object. -Sermersheim Internet-Draft - Expires Aug 2004 Page 24 - Lightweight Directory Access Protocol Version 3 - Other kinds of URIs may be returned. The syntax and semantics of such URIs is left to future specifications. Clients may ignore URIs that they do not support. 4.5.3.1. Examples For example, suppose the contacted server (hosta) holds the entry and the entry . It knows that either LDAP-capable servers (hostb) or (hostc) hold (one is the master and the other server @@ -1358,20 +1352,21 @@ return the following: SearchResultEntry for DC=Example,DC=NET SearchResultEntry for CN=Manager,DC=Example,DC=NET SearchResultReference { ldap://hostb/OU=People,DC=Example,DC=NET??sub ldap://hostc/OU=People,DC=Example,DC=NET??sub } SearchResultReference { ldap://hostd/OU=Roles,DC=Example,DC=NET??sub } SearchResultDone (success) + Lightweight Directory Access Protocol Version 3 Client implementors should note that when following a SearchResultReference, additional SearchResultReference may be generated. Continuing the example, if the client contacted the server (hostb) and issued the search for the subtree , the server might respond as follows: SearchResultEntry for OU=People,DC=Example,DC=NET SearchResultReference { ldap://hoste/OU=Managers,OU=People,DC=Example,DC=NET??sub } @@ -1384,26 +1379,24 @@ SearchResultEntry for CN=Manager,DC=Example,DC=NET SearchResultReference { ldap://hostb/OU=People,DC=Example,DC=NET??base ldap://hostc/OU=People,DC=Example,DC=NET??base } SearchResultReference { ldap://hostd/OU=Roles,DC=Example,DC=NET??base } SearchResultDone (success) If the contacted server does not hold the base object for the search, - then it will return a referral to the client. For example, if the - client requests a subtree search of to hosta, the - server may return only a SearchResultDone containing a referral. - -Sermersheim Internet-Draft - Expires Aug 2004 Page 25 - Lightweight Directory Access Protocol Version 3 + but has knowledge of its possible location, then it may return a + referral to the client. In this case, if the client requests a + subtree search of to hosta, the server returns a + SearchResultDone containing a referral. SearchResultDone (referral) { ldap://hostg/DC=Example,DC=ORG??sub } 4.6. Modify Operation The Modify Operation allows a client to request that a modification of an entry be performed on its behalf by a server. The Modify Request is defined as follows: @@ -1413,77 +1406,78 @@ operation ENUMERATED { add (0), delete (1), replace (2) }, modification PartialAttribute } } Fields of the Modify Request are: - object: The name of the object to be modified. The value of this field contains the DN of the entry to be modified. The server + Lightweight Directory Access Protocol Version 3 + SHALL NOT perform any alias dereferencing in determining the object to be modified. - changes: A list of modifications to be performed on the entry. The entire list of modifications MUST be performed in the order they are listed as a single atomic operation. While individual modifications may violate certain aspects of the directory schema (such as the object class definition and DIT content rule), the resulting entry after the entire list of modifications is - performed MUST conform to the requirements of the directory schema - [Models]. + performed MUST conform to the requirements of the directory model + and controlling schema [Models]. - operation: Used to specify the type of modification being performed. Each operation type acts on the following modification. The values of this field have the following semantics respectively: add: add values listed to the modification attribute, creating the attribute if necessary; delete: delete values listed from the modification attribute, removing the entire attribute if no values are listed, or if all current values of the attribute are listed for deletion; replace: replace all existing values of the modification attribute with the new values listed, creating the attribute if it did not already exist. A replace with no value will delete the entire attribute if it exists, and is ignored if the attribute does not exist. -Sermersheim Internet-Draft - Expires Aug 2004 Page 26 - Lightweight Directory Access Protocol Version 3 - - modification: A PartialAttribute (which may have an empty SET of vals) used to hold the attribute type or attribute type and values being modified. Upon receipt of a Modify Request, the server attempts to perform the necessary modifications to the DIT and returns the result in a Modify Response, defined as follows: ModifyResponse ::= [APPLICATION 7] LDAPResult The server will return to the client a single Modify Response indicating either the successful completion of the DIT modification, or the reason that the modification failed. Due to the requirement for atomicity in applying the list of modifications in the Modify Request, the client may expect that no modifications of the DIT have been performed if the Modify Response received indicates any sort of error, and that all requested modifications have been performed if the Modify Response indicates successful completion of the Modify - Operation. If the association changes or the connection fails, - whether the modification occurred or not is indeterminate. + Operation. If the association changes or the stream fails, whether + the modification occurred or not is indeterminate. The Modify Operation cannot be used to remove from an entry any of its distinguished values, i.e. those values which form the entry's relative distinguished name. An attempt to do so will result in the + Lightweight Directory Access Protocol Version 3 + server returning the notAllowedOnRDN result code. The Modify DN Operation described in Section 4.9 is used to rename an entry. Note that due to the simplifications made in LDAP, there is not a direct mapping of the changes in an LDAP ModifyRequest onto the changes of a DAP ModifyEntry operation, and different implementations of LDAP-DAP gateways may use different means of representing the change. If successful, the final effect of the operations on the entry MUST be identical. @@ -1497,54 +1491,47 @@ attributes AttributeList } AttributeList ::= SEQUENCE OF attribute Attribute Fields of the Add Request are: - entry: the name of the entry to be added. The server SHALL NOT dereference any aliases in locating the entry to be added. - attributes: the list of attributes that, along with those from the - RDN, make up the content of the entry being added. Clients MUST + RDN, make up the content of the entry being added. Clients MAY or + MAY NOT include the RDN attribute in this list. Clients MUST include the 'objectClass' attribute, and values of any mandatory - -Sermersheim Internet-Draft - Expires Aug 2004 Page 27 - Lightweight Directory Access Protocol Version 3 - attributes of the listed object classes. Clients MUST NOT supply NO-USER-MODIFICATION attributes such as the createTimestamp or creatorsName attributes, since the server maintains these automatically. The entry named in the entry field of the AddRequest MUST NOT exist for the AddRequest to succeed. The immediate superior (parent) of an object or alias entry to be added MUST exist. For example, if the client attempted to add , the entry did not exist, and the entry did exist, then the server would return the noSuchObject result code with the matchedDN field containing . - If the entry to be added would not fall within a naming context - [Section 5 of Models] held by the server, and the server has - knowledge of where that entry is to be located, a referral to the - server(s) holding the parent entry should be returned. - Server implementations SHOULD NOT restrict where entries can be located in the Directory unless DIT structure rules are in place. Some servers allow the administrator to restrict the classes of entries which can be added to the Directory. Upon receipt of an Add Request, a server will attempt to add the requested entry. The result of the add attempt will be returned to the client in the Add Response, defined as follows: AddResponse ::= [APPLICATION 9] LDAPResult + Lightweight Directory Access Protocol Version 3 A response of success indicates that the new entry has been added to the Directory. 4.8. Delete Operation The Delete Operation allows a client to request the removal of an entry from the Directory. The Delete Request is defined as follows: DelRequest ::= [APPLICATION 10] LDAPDN @@ -1555,50 +1542,51 @@ Only leaf entries (those with no subordinate entries) can be deleted with this operation. Upon receipt of a Delete Request, a server will attempt to perform the entry removal requested and return the result in the Delete Response defined as follows: DelResponse ::= [APPLICATION 11] LDAPResult -Sermersheim Internet-Draft - Expires Aug 2004 Page 28 - Lightweight Directory Access Protocol Version 3 - 4.9. Modify DN Operation The Modify DN Operation allows a client to change the Relative Distinguished Name (RDN) of an entry in the Directory, and/or to move a subtree of entries to a new location in the Directory. The Modify DN Request is defined as follows: ModifyDNRequest ::= [APPLICATION 12] SEQUENCE { entry LDAPDN, newrdn RelativeLDAPDN, deleteoldrdn BOOLEAN, newSuperior [0] LDAPDN OPTIONAL } Fields of the Modify DN Request are: - entry: the name of the entry to be changed. This entry may or may not have subordinate entries. - - newrdn: the new RDN of the entry. If an attribute value in the - newrdn does not already exist in the entry (either as part of the - old RDN or as a non-distinguished value), it is added. If it - cannot be added, an appropriate error is returned. + - newrdn: the new RDN of the entry. If the operation moves the entry + to a new superior without changing its RDN, the value of the old + RDN is supplied for this parameter. + Attribute values of the new RDN not matching any attribute value + of the entry are added to the entry and an appropriate error is + returned if this fails. - deleteoldrdn: a boolean field that controls whether the old RDN attribute values are to be retained as attributes of the entry, or deleted from the entry. + Lightweight Directory Access Protocol Version 3 + - newSuperior: if present, this is the name of an existing object entry which becomes the immediate superior (parent) of the existing entry. The server SHALL NOT dereference any aliases in locating the objects named in entry or newSuperior. Upon receipt of a ModifyDNRequest, a server will attempt to perform the name change and return the result in the Modify DN Response, defined as follows: @@ -1611,23 +1599,20 @@ rename the entry to be . If there was already an entry with that name, the operation would fail with the entryAlreadyExists result code. The object named in newSuperior MUST exist. For example, if the client attempted to add , the entry did not exist, and the entry did exist, then the server would return the noSuchObject result code with the matchedDN field containing . -Sermersheim Internet-Draft - Expires Aug 2004 Page 29 - Lightweight Directory Access Protocol Version 3 - If the deleteoldrdn field is TRUE, the attribute values forming the old RDN but not the new RDN are deleted from the entry. If the deleteoldrdn field is FALSE, the attribute values forming the old RDN will be retained as non-distinguished attribute values of the entry. The server MUST fail the operation and return an error in the result code if the setting of the deleteoldrdn field would cause a schema inconsistency in the entry. Note that X.500 restricts the ModifyDN operation to only affect entries that are contained within a single server. If the LDAP server @@ -1639,105 +1624,102 @@ 4.10. Compare Operation The Compare Operation allows a client to compare an assertion value with the values of a particular attribute in a particular entry in the Directory. The Compare Request is defined as follows: CompareRequest ::= [APPLICATION 14] SEQUENCE { entry LDAPDN, ava AttributeValueAssertion } + Lightweight Directory Access Protocol Version 3 Fields of the Compare Request are: - entry: the name of the entry to be compared. The server SHALL NOT dereference any aliases in locating the entry to be compared. - ava: holds the attribute description and assertion value with which an attribute in the entry is to be compared. Upon receipt of a Compare Request, a server will attempt to perform the requested comparison and return the result in the Compare Response, defined as follows: CompareResponse ::= [APPLICATION 15] LDAPResult The resultCode field is set to compareTrue, compareFalse, or an appropriate error. compareTrue indicates that the assertion value in - the ava field is equivalent to a value of the attribute or subtype - (according to the attribute's EQUALITY matching rule). compareFalse - indicates that the comparison of the assertion value in the ava field - and the values of the attribute or subtype resulted in an Undefined - (Section 4.5.1) or non-equivalent match. + the ava field matches a value of the attribute or subtype according + to the attribute's EQUALITY matching rule. compareFalse indicates + that the assertion value in the ava field and the values of the + attribute or subtype did not match or was Undefined (Section 4.5.1). In the event that the attribute or subtype is not present in the entry, the resultCode field is set to noSuchAttribute. If the attribute is unknown, the resultCode is set to undefinedAttributeType. If the attribute or subtype has no equality matching rule, innapropriateMatching is returned in the resultCode. -Sermersheim Internet-Draft - Expires Aug 2004 Page 30 - Lightweight Directory Access Protocol Version 3 - Note that some directory systems may establish access controls which permit the values of certain attributes (such as userPassword) to be compared but not interrogated by other means. 4.11. Abandon Operation The function of the Abandon Operation is to allow a client to request that the server abandon an outstanding operation. The Abandon Request is defined as follows: AbandonRequest ::= [APPLICATION 16] MessageID The MessageID is that of an operation which was requested earlier in this LDAP association. The abandon request itself has its own message id. This is distinct from the id of the earlier operation being abandoned. There is no response defined in the Abandon operation. Upon receipt of an AbandonRequest, the server MAY abandon the operation identified - by the MessageID. Operation responses are not sent for successfully - abandoned operations, thus the application of the Abandon operation - is limited to uses where the client does not require an indication of - its outcome. + by the MessageID. Since the client cannot tell the difference between + a successfully abandoned operation and an outstanding operation, the + application of the Abandon operation is limited to uses where the + client does not require an indication of its outcome. Abandon, Bind, Unbind, and StartTLS operations cannot be abandoned. - The ability to abandon other (particularly update) operations is at - the discretion of the server. + + Lightweight Directory Access Protocol Version 3 In the event that a server receives an Abandon Request on a Search Operation in the midst of transmitting responses to the search, that server MUST cease transmitting entry responses to the abandoned request immediately, and MUST NOT send the SearchResponseDone. Of course, the server MUST ensure that only properly encoded LDAPMessage PDUs are transmitted. + The ability to abandon other (particularly update) operations is at + the discretion of the server. + Clients should not send abandon requests for the same operation multiple times, and MUST also be prepared to receive results from operations it has abandoned (since these may have been in transit when the abandon was requested, or are not able to be abandoned). Servers MUST discard abandon requests for message IDs they do not recognize, for operations which cannot be abandoned, and for operations which have already been abandoned. 4.12. Extended Operation The extended operation allows additional operations to be defined for services not already available in the protocol. For example, to add operations to install transport layer security (see Section 4.14). -Sermersheim Internet-Draft - Expires Aug 2004 Page 31 - Lightweight Directory Access Protocol Version 3 - The extended operation allows clients to make requests and receive responses with predefined syntaxes and semantics. These may be defined in RFCs or be private to particular implementations. Each extended operation consists of an extended request and an extended response. ExtendedRequest ::= [APPLICATION 23] SEQUENCE { requestName [0] LDAPOID, requestValue [1] OCTET STRING OPTIONAL } @@ -1753,48 +1735,50 @@ ExtendedResponse ::= [APPLICATION 24] SEQUENCE { COMPONENTS OF LDAPResult, responseName [10] LDAPOID OPTIONAL, responseValue [11] OCTET STRING OPTIONAL } The responseName is typically not required to be present as the syntax and semantics of the response (including the format of the responseValue) is implicitly known and associated with the request by the messageID. + Lightweight Directory Access Protocol Version 3 + If the requestName is not recognized by the server, the server MUST NOT provide a responseName nor a responseValue and MUST return a resultCode of protocolError. The requestValue and responseValue fields contain any information associated with the operation. The format of these fields is defined by the specification of the extended operation. Implementations MUST be prepared to handle arbitrary contents of these fields, including zero bytes. Values that are defined in terms of ASN.1 and BER encoded - according to Section 5.1, also follow the extensibility rules in + according to Section 5.2, also follow the extensibility rules in Section 4. It is RECOMMENDED that servers list the requestName of extended operations they support in the 'supportedExtension' attribute of the root DSE [Models]. Extended operations may be specified in other documents. The specification of an extended operation consists of: - - the OBJECT IDENTIFIER assigned to the requestName (and possibly - responseName), + - the OBJECT IDENTIFIER assigned to the requestName, + + - the OBJECT IDENTIFIER (if any) assigned to the responseName (note + that the same OBJECT IDENTIFIER my be used for both the + requestName and responseName), - the format of the contents of the requestValue and responseValue (if any), and -Sermersheim Internet-Draft - Expires Aug 2004 Page 32 - Lightweight Directory Access Protocol Version 3 - - the semantics of the operation. 4.13. IntermediateResponse Message While the Search operation provides a mechanism to return multiple response messages for a single search request, other operations, by nature, do not provide for multiple response messages. The IntermediateResponse message provides a general mechanism for defining single-request/multiple-response operations in LDAP. This @@ -1802,114 +1786,93 @@ operation to define new single-request/multiple-response operations or in conjunction with a control when extending existing LDAP operations in a way that requires them to return intermediate response information. It is intended that the definitions and descriptions of extended operations and controls that make use of the IntermediateResponse message will define the circumstances when an IntermediateResponse message can be sent by a server and the associated meaning of an IntermediateResponse message sent in a particular circumstance. - Similarly, it is intended that clients will explicitly solicit - IntermediateResponse messages by issuing operations that specifically - call for their return. IntermediateResponse ::= [APPLICATION 25] SEQUENCE { responseName [0] LDAPOID OPTIONAL, + Lightweight Directory Access Protocol Version 3 + responseValue [1] OCTET STRING OPTIONAL } IntermediateResponse messages SHALL NOT be returned to the client unless the client issues a request that specifically solicits their return. This document defines two forms of solicitation: extended - operation and request control. + operation and request control. IntermediateResponse messages are + specified in documents describing the manner in which they are + solicited (i.e. in the extended operation or request control + specification that uses them). These specifications include: + + - the OBJECT IDENTIFIER (if any) assigned to the responseName, + + - the format of the contents of the responseValue, and + + - the semantics associated with the IntermediateResponse message. + + Extensions that allow the return of multiple types of + IntermediateResponse messages SHALL identify those types using unique + responseName values (note that one of these may specify no value). - Although the responseName and responseValue are optional in some - circumstances, generally speaking IntermediateResponse messages have - a predefined responseName and a responseValue. The value of the - responseName (if present), the syntax of the responseValue (if - present) and the semantics associated with a particular - IntermediateResponse message MUST be specified in documents - describing the extended operation or request control that uses them. Sections 4.13.1 and 4.13.2 describe additional requirements on the inclusion of responseName and responseValue in IntermediateResponse messages. 4.13.1. Usage with LDAP ExtendedRequest and ExtendedResponse A single-request/multiple-response operation may be defined using a single ExtendedRequest message to solicit zero or more IntermediateResponse messages of one or more kinds followed by an ExtendedResponse message. -Sermersheim Internet-Draft - Expires Aug 2004 Page 33 - Lightweight Directory Access Protocol Version 3 - - An extended operation that defines the return of multiple kinds of - IntermediateResponse messages MUST provide and document a mechanism - for the client to distinguish the kind of IntermediateResponse - message being sent. This SHALL be accomplished by using different - responseName values for each type of IntermediateResponse message - associated with the extended operation or by including identifying - information in the responseValue of each type of IntermediateResponse - message associated with the extended operation. - 4.13.2. Usage with LDAP Request Controls - Any LDAP operation may be extended by the addition of one or more - controls ([RFC2251] Section 4.1.12). A control's semantics may - include the return of zero or more IntermediateResponse messages - prior to returning the final result code for the operation. One or - more kinds of IntermediateResponse messages may be sent in response - to a request control. + A control's semantics may include the return of zero or more + IntermediateResponse messages prior to returning the final result + code for the operation. One or more kinds of IntermediateResponse + messages may be sent in response to a request control. All IntermediateResponse messages associated with request controls SHALL include a responseName. This requirement ensures that the client can correctly identify the source of IntermediateResponse messages when: - two or more controls using IntermediateResponse messages are included in a request for any LDAP operation or - one or more controls using IntermediateResponse messages are included in a request with an LDAP extended operation that uses IntermediateResponse messages. - A request control that defines the return of multiple kinds of - IntermediateResponse messages MUST provide and document a mechanism - for the client to distinguish the kind of IntermediateResponse - message being sent. This SHALL be accomplished by using different - responseName values for each type of IntermediateResponse message - associated with the request control or by including identifying - information in the responseValue of each type of IntermediateResponse - message associated with the request control. - 4.14. StartTLS Operation + Lightweight Directory Access Protocol Version 3 The Start Transport Layer Security (StartTLS) operation provides the - ability to establish Transport Layer Security ([TLS]) on an LDAP - connection. The StartTLS operation is defined using the extended - operation mechanism described in Section 4.12. + ability to establish a TLS-protected connection. The StartTLS + operation is defined using the extended operation mechanism described + in Section 4.12. 4.14.1. StartTLS Request A client requests TLS establishment by transmitting a StartTLS request PDU to the server. The StartTLS request is defined in terms - -Sermersheim Internet-Draft - Expires Aug 2004 Page 34 - Lightweight Directory Access Protocol Version 3 - of an ExtendedRequest. The requestName is "1.3.6.1.4.1.1466.20037", and the requestValue field is always absent. The client MUST NOT send any PDUs on this connection following this - request until it receives a StartTLS extended response and completes - TLS negotiations. + request until it receives a StartTLS extended response and, in the + case of a successful response, completes TLS negotiations. 4.14.2. StartTLS Response When a StartTLS request is made, servers supporting the operation MUST return a StartTLS response PDU to the requestor. The responseName is also "1.3.6.1.4.1.1466.20037", and the responseValue field is absent. The server provides a resultCode field to either success or one of the other values outlined in Section 4.14.2.2. @@ -1928,96 +1891,123 @@ operation: - operationsError: operations sequencing incorrect; e.g. TLS is already established. - protocolError: TLS is not supported or incorrect PDU structure. - unavailable: Some major problem with TLS, or the server is shutting down. + Lightweight Directory Access Protocol Version 3 + The server MUST return operationsError if the client violates any of the StartTLS extended operation sequencing requirements described in Section 4 of [AuthMeth]. If the server does not support TLS (whether by design or by current - configuration), it MUST return the protocolError resultCode. The - client's current association is unaffected if the server does not - support TLS. The client may proceed with any LDAP operation, or it - may close the connection. + configuration), it MUST return the protocolError resultCode. In this + event, the client may proceed with any LDAP operation, or it may + close the stream. The server MUST return unavailable if it supports TLS but cannot - establish a TLS connection for some reason, e.g. the certificate - -Sermersheim Internet-Draft - Expires Aug 2004 Page 35 - Lightweight Directory Access Protocol Version 3 + install the TLS layer for some reason, e.g. the certificate server + not responding, it cannot contact its TLS implementation, or if the + server is in process of shutting down. The client may retry the + StartTLS operation, or it may proceed with any other LDAP operation, + or it may close the stream. - server not responding, it cannot contact its TLS implementation, or - if the server is in process of shutting down. The client may retry - the StartTLS operation, or it may proceed with any other LDAP - operation, or it may close the LDAP connection. +4.14.3. Removal of the TLS Layer -4.14.3. Closing a TLS Connection + Two forms of TLS layer -- graceful and abrupt -- are supported. These + do not involve LDAP PDUs, but are preformed at the underlying layers. - Two forms of TLS connection closure -- graceful and abrupt -- are - supported. These do not involve LDAP PDUs, but are preformed at the - underlying layers. + If the stream is closed, outstanding operations are handled as + specified in Section 5.1. -4.14.3.1. Graceful Closure +4.14.3.1. Graceful Removal - Either the client or server MAY terminate the TLS connection and - leave the LDAP connection intact by sending and receiving a TLS - closure alert. + Either the client or server MAY remove the TLS layer and leave the + connection intact by sending and receiving a TLS closure alert. The initiating protocol peer sends the TLS closure alert. If it - wishes to leave the LDAP connection intact, it then MUST cease to - send further PDUs and MUST ignore any received PDUs until it receives - a TLS closure alert from the other peer. + wishes to leave the connection intact, it then MUST cease to send + further PDUs and MUST ignore any received PDUs until it receives a + TLS closure alert from the other peer. Once the initiating protocol peer receives a TLS closure alert from the other peer it MAY send and receive LDAP PDUs. When a protocol peer receives the initial TLS closure alert, it may - choose to allow the underlying LDAP connection to remain intact. In - this case, it MUST immediately transmit a TLS closure alert. - Following this, it MAY send and receive LDAP PDUs. + choose to allow the connection to remain intact. In this case, it + MUST immediately transmit a TLS closure alert. Following this, it MAY + send and receive LDAP PDUs. - Protocol peers MAY drop the underlying LDAP connection after sending - or receiving a TLS closure alert. + Protocol peers MAY close the stream after sending or receiving a TLS + closure alert. - After the TLS connection has been closed, the server MUST NOT send - responses to any request message received before the TLS closure. - Thus, clients wishing to receive responses to messages sent while the - TLS connection is intact MUST wait for those message responses before - sending the TLS closure alert. + After the TLS layer has been removed, the server MUST NOT send + responses to any request message received before the TLS closure + alert. Thus, clients wishing to receive responses to messages sent + while the TLS layer is intact MUST wait for those message responses + before sending the TLS closure alert. -4.14.3.2. Abrupt Closure + Lightweight Directory Access Protocol Version 3 - Either the client or server MAY abruptly close the TLS connection by - dropping the underlying transfer protocol connection. In this - circumstance, a server MAY send the client a Notice of Disconnection - before dropping the underlying LDAP connection. Outstanding - operations are handled as specified in Section 5.2. +4.14.3.2. Abrupt Removal -5. Protocol Element Encodings and Transfer + Either the client or server MAY abruptly remove the TLS layer by + closing the stream. In this circumstance, a server MAY send the + client a Notice of Disconnection before closing the stream. -Sermersheim Internet-Draft - Expires Aug 2004 Page 36 - Lightweight Directory Access Protocol Version 3 +5. Protocol Encoding, Connection, and Transfer - One underlying service, LDAP over TCP, is defined here. This service - is generally applicable to applications providing or consuming X.500- - based directory services on the Internet. + This protocol is designed to run over connection-oriented, reliable + transports, where the data stream is divided into octets (8-bit + units), with each octet being significant. + + One underlying service, LDAP over TCP, is defined in Section + 5.3. This service is generally applicable to applications providing + or consuming X.500-based directory services on the Internet. This + specification was generally written with the TCP mapping in mind. + Specifications detailing other mappings may encounter various + obstacles. Implementations of LDAP over TCP MUST implement the mapping as - described in Section 5.2.1 + described in Section 5.3 -5.1. Protocol Encoding + This table illustrates the relationship between the different layers + involved in an exchange between two protocol peers: + +------------+ | + | connection | | + +------------+ > LDAP PDU | + +------------+ < data | + | SASL layer | | + +------------+ > SASL-protected data | + +------------+ < data | + | TLS layer | | + +------------+ > TLS-protected data | Application + +------------+ < data +------------ + | stream | | Transport + +------------+ + +5.1 Operation and Connection Relationship + + Protocol operations are tied to a connection. If the stream is + closed, any outstanding operations tied to the connection are, when + possible, abandoned, and when not possible, completed without + transmission of the response. Also, if the stream is closed, the + client MUST NOT assume that any outstanding update operations tied to + the connection have succeeded or failed. + +5.2. Protocol Encoding + Lightweight Directory Access Protocol Version 3 The protocol elements of LDAP SHALL be encoded for exchange using the Basic Encoding Rules [BER] of [ASN.1] with the following restrictions: - Only the definite form of length encoding is used. - OCTET STRING values are encoded in the primitive form only. - If the value of a BOOLEAN type is true, the encoding of the value @@ -2027,100 +2017,82 @@ BOOLEAN and INTEGER types have default values in this protocol definition. These restrictions are meant to ease the overhead of encoding and decoding certain elements in BER. These restrictions do not apply to ASN.1 types encapsulated inside of OCTET STRING values, such as attribute values, unless otherwise stated. -5.2. Transfer Protocols - - This protocol is designed to run over connection-oriented, reliable - transports, with all 8 bits in an octet being significant in the data - stream. Protocol operations are tied to a connection, thus if the - connection is closed or dropped, the operation is aborted. When this - happens, any outstanding operations on the server are, when possible, - abandoned, and when not possible, completed without transmission of - the response. Also, if the connection is closed or dropped, the - client MUST NOT assume that any outstanding requests which modified - the Directory have succeeded or failed. - -5.2.1. Transmission Control Protocol (TCP) +5.3. Transmission Control Protocol (TCP) The encoded LDAPMessage PDUs are mapped directly onto the [TCP] - bytestream using the BER-based encoding described in Section 5.1. It + bytestream using the BER-based encoding described in Section 5.2. It is recommended that server implementations running over the TCP provide a protocol listener on the Internet Assigned Numbers Authority (IANA)-assigned LDAP port, 389 [PortReg]. Servers may - -Sermersheim Internet-Draft - Expires Aug 2004 Page 37 - Lightweight Directory Access Protocol Version 3 - instead provide a listener on a different port number. Clients MUST support contacting servers on any valid TCP port. 6. Security Considerations This version of the protocol provides facilities for simple authentication using a cleartext password, as well as any [SASL] - mechanism. SASL allows for integrity and privacy services to be - negotiated. + mechanism. Installing SASL layers can provide integrity and privacy + services. It is also permitted that the server can return its credentials to the client, if it chooses to do so. Use of cleartext password is strongly discouraged where the underlying transport service cannot guarantee confidentiality and may result in disclosure of the password to unauthorized parties. Servers are encouraged to prevent directory modifications by clients that have authenticated anonymously [AuthMeth]. - Requirements of authentication methods, SASL mechanisms, and TLS are - described in [AuthMeth]. + Security considerations for authentication methods, SASL mechanisms, + and TLS are described in [AuthMeth]. + + Lightweight Directory Access Protocol Version 3 It should be noted that SASL authentication exchanges do not provide data confidentiality nor integrity protection for the version or name fields of the bind request nor the resultCode, diagnosticMessage, or referral fields of the bind response nor of any information contained in controls attached to bind request or responses. Thus information contained in these fields SHOULD NOT be relied on unless otherwise protected (such as by establishing protections at the transport layer). - Server implementors should plan for the possibility of an identity - associated with an LDAP connection being deleted, renamed, or - modified, and take appropriate actions to prevent insecure side - effects. Likewise, server implementors should plan for the - possibility of an associated identity's credentials becoming invalid, - or an identity's privileges being changed. The ways in which these - issues are addressed are application and/or implementation specific. + Server implementors should plan for the possibility of an identity in + and association being deleted, renamed, or modified, and take + appropriate actions to prevent insecure side effects. Likewise, + server implementors should plan for the possibility of an associated + identity's credentials becoming invalid, or an identity's privileges + being changed. The ways in which these issues are addressed are + application and/or implementation specific. Implementations which cache attributes and entries obtained via LDAP MUST ensure that access controls are maintained if that information is to be provided to multiple clients, since servers may have access control policies which prevent the return of entries or attributes in search results except to particular authenticated clients. For example, caches could serve result information only to the client whose request caused it to be in the cache. Servers may return referrals or search result references which redirect clients to peer servers. It is possible for a rogue application to inject such referrals into the data stream in an attempt to redirect a client to a rogue server. Clients are advised to be aware of this, and possibly reject referrals when - -Sermersheim Internet-Draft - Expires Aug 2004 Page 38 - Lightweight Directory Access Protocol Version 3 - confidentiality measures are not in place. Clients are advised to reject referrals from the StartTLS operation. The matchedDN and diagnosticMessage fields, as well as some resultCode values (e.g., attributeOrValueExists and entryAlreadyExists), could disclose the presence the specific data in the directory which is subject to access and other administrative controls. Server implementations should restrict access to protected information equally under both normal and error conditions. @@ -2131,20 +2103,22 @@ 7. Acknowledgements This document is based on RFC 2251 by Mark Wahl, Tim Howes, and Steve Kille. It is also based on RFC 2830 by Jeff Hodges, RL "Bob" Morgan, and Mark Wahl. It is also based on [LIMR] by Roger Harrison, and Kurt Zeilenga. Notable amounts of technical reviews and content were provided by Kurt Zeilenga, Steven Legg, and Hallvard Furuseth. Their work along with the input of individuals of the IETF ASID, LDAPEXT, LDUP, LDAPBIS, and other Working Groups is gratefully acknowledged. + Lightweight Directory Access Protocol Version 3 + 8. Normative References [ABNF] Crocker, D. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", RFC 2234, November 1997. [ASN.1] ITU-T Recommendation X.680 (07/2002) | ISO/IEC 8824-1:2002 "Information Technology - Abstract Syntax Notation One (ASN.1): Specification of basic notation" [AuthMeth] Harrison, R., "LDAP: Authentication Methods and Connection @@ -2160,23 +2134,20 @@ [IP] Postel, J., "Internet Protocol", STD5 and RFC 791, September 1981 [ISO10646] Universal Multiple-Octet Coded Character Set (UCS) - Architecture and Basic Multilingual Plane, ISO/IEC 10646-1 : 1993. [Keyword] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, March 1997. -Sermersheim Internet-Draft - Expires Aug 2004 Page 39 - Lightweight Directory Access Protocol Version 3 - [LDAPDN] Zeilenga, K., "LDAP: String Representation of Distinguished Names", draft-ietf-ldapbis-dn-xx.txt, (a work in progress). [LDAPIANA] Zeilenga, K., "IANA Considerations for LDAP", draft-ietf- ldapbis-bcp64-xx.txt, (a work in progress). [LDAPURL] Smith, M., "LDAP: Uniform Resource Locator", draft-ietf- ldapbis-url-xx.txt, (a work in progress). @@ -2187,20 +2158,22 @@ [Models] Zeilenga, K., "LDAP: Directory Information Models", draft- ietf-ldapbis-models-xx.txt (a work in progress). [Roadmap] Zeilenga, K., "LDAP: Technical Specification Road Map", draft-ietf-ldapbis-roadmap-xx.txt (a work in progress). [SASL] Melnikov, A., "Simple Authentication and Security Layer", draft-ietf-sasl-rfc2222bis-xx.txt (a work in progress). + Lightweight Directory Access Protocol Version 3 + [SASLPrep] Zeilenga, K., "Stringprep profile for user names and passwords", draft-ietf-sasl-saslprep-xx.txt, (a work in progress). [StringPrep] Hoffman P. and M. Blanchet, "Preparation of Internationalized Strings ('stringprep')", draft-hoffman- rfc3454bis-xx.txt, a work in progress. [Syntaxes] Legg, S., and K. Dally, "LDAP: Syntaxes and Matching Rules", draft-ietf-ldapbis-syntaxes-xx.txt, (a work in @@ -2217,42 +2190,40 @@ (Reading, MA, Addison-Wesley, 2000. ISBN 0-201-61633-5), as amended by the "Unicode Standard Annex #27: Unicode 3.1" (http://www.unicode.org/reports/tr27/) and by the "Unicode Standard Annex #28: Unicode 3.2" (http://www.unicode.org/reports/tr28/). [URI] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifiers (URI): Generic Syntax", RFC 2396, August 1998. -Sermersheim Internet-Draft - Expires Aug 2004 Page 40 - Lightweight Directory Access Protocol Version 3 - [UTF-8] Yergeau, F., "UTF-8, a transformation format of ISO 10646", STD63 and RFC3629, November 2003. [X.500] ITU-T Rec. X.500, "The Directory: Overview of Concepts, Models and Service", 1993. [X.501] ITU-T Rec. X.501, "The Directory: Models", 1993. [X.511] ITU-T Rec. X.511, "The Directory: Abstract Service Definition", 1993. 9. Informative References [CERT] The CERT(R) Center, http://www.cert.org [PortReg] IANA, "Port Numbers", http://www.iana.org/assignments/port-numbers 10. IANA Considerations + Lightweight Directory Access Protocol Version 3 It is requested that the Internet Assigned Numbers Authority (IANA) update the LDAP result code registry to indicate that this document provides the definitive technical specification for result codes 0- 36, 48-54, 64-70, 80-90. It is requested that the IANA update the LDAP Protocol Mechanism registry to indicate that this document and [AuthMeth] provides the definitive technical specification for the Start TLS (1.3.6.1.4.1.1466.20037) extended operation. @@ -2261,90 +2232,99 @@ Appendix B with this RFC number at publication. 11. Editor's Address Jim Sermersheim Novell, Inc. 1800 South Novell Place Provo, Utah 84606, USA jimse@novell.com +1 801 861-3088 - -Sermersheim Internet-Draft - Expires Aug 2004 Page 41 Lightweight Directory Access Protocol Version 3 Appendix A - LDAP Result Codes This normative appendix details additional considerations regarding LDAP result codes and provides a brief, general description of each LDAP result code enumerated in Section 4.1.9. Additional result codes MAY be defined for use with extensions [LDAPIANA]. Client implementations SHALL treat any result code which they do not recognize as an unknown error condition. A.1 Non-Error Result Codes These result codes (called "non-error" result codes) do not indicate an error condition: success (0), + compareFalse (5), compareTrue (6), - compareFalse (7), referral (10), and saslBindInProgress (14). The success, compareTrue, and compareFalse result codes indicate successful completion (and, hence, are referred to as "successful" result codes). The referral and saslBindInProgress result codes indicate the client is required to take additional action to complete the operation. A.2 Result Codes Existing LDAP result codes are described as follows: success (0) Indicates the successful completion of an operation. Note: this code is not used with the compare operation. See - compareTrue (5) and compareFalse (6). + compareFalse (5) and compareTrue (6). operationsError (1) Indicates that the operation is not properly sequenced with relation to other operations (of same or different type). For example, this code is returned if the client attempts to StartTLS [TLS] while there are other operations outstanding - or if TLS was already established. + or if a TLS layer was already installed. protocolError (2) Indicates the server received data which has incorrect structure. For bind operation only, this code is also used to indicate that the server does not support the requested protocol version. -Sermersheim Internet-Draft - Expires Aug 2004 Page 42 Lightweight Directory Access Protocol Version 3 + For the extended operation only, this code indicates that the + server does not recognize the requestName. + + For the Start TLS operation, this code may also indicate that + the server does not currently support Start TLS (even though + it may recognize the requestName). + + For request operations specifying multiple controls, this may + be used to indicate that the server cannot ignore the order + of the controls as specified. + timeLimitExceeded (3) Indicates that the time limit specified by the client was exceeded before the operation could be completed. sizeLimitExceeded (4) Indicates that the size limit specified by the client was exceeded before the operation could be completed. compareFalse (5) Indicates that the compare operation has successfully - completed and the assertion has evaluated to FALSE. + completed and the assertion has evaluated to FALSE or + Undefined. compareTrue (6) Indicates that the compare operation has successfully completed and the assertion has evaluated to TRUE. authMethodNotSupported (7) Indicates that the authentication method or mechanism is not supported. strongAuthRequired (8) @@ -2362,35 +2342,34 @@ Indicates that an administrative limit has been exceeded. unavailableCriticalExtension (12) Indicates that the server is unable or unwilling to perform a critical control (see Section 4.1.11). confidentialityRequired (13) Indicates that data confidentiality protections are required. saslBindInProgress (14) + Lightweight Directory Access Protocol Version 3 + Indicates the server requires the client to send a new bind request, with the same SASL mechanism, to continue the authentication process (see Section 4.2). noSuchAttribute (16) Indicates that the named entry does not contain the specified attribute or attribute value. undefinedAttributeType (17) Indicates that a request field contains an unrecognized attribute description. -Sermersheim Internet-Draft - Expires Aug 2004 Page 43 - Lightweight Directory Access Protocol Version 3 - inappropriateMatching (18) Indicates that an attempt was made, e.g. in an assertion, to use a matching rule not defined for the attribute type concerned. constraintViolation (19) Indicates that the client supplied an attribute value which does not conform to the constraints placed upon it by the data model. @@ -2419,36 +2398,35 @@ base, target entry, ModifyDN newrdn, etc.) of a request does not conform to the required syntax or contains attribute values which do not conform to the syntax of the attribute's type. aliasDereferencingProblem (36) Indicates that a problem occurred while dereferencing an alias. Typically an alias was encountered in a situation where it was not allowed or where access was denied. + Lightweight Directory Access Protocol Version 3 + inappropriateAuthentication (48) Indicates the server requires the client which had attempted to bind anonymously or without supplying credentials to provide some form of credentials. invalidCredentials (49) Indicates that the provided credentials (e.g. the user's name and password) are invalid. insufficientAccessRights (50) Indicates that the client does not have sufficient access rights to perform the operation. -Sermersheim Internet-Draft - Expires Aug 2004 Page 44 - Lightweight Directory Access Protocol Version 3 - busy (51) Indicates that the server is too busy to service the operation. unavailable (52) Indicates that the server is shutting down or a subsystem necessary to complete the operation is offline. unwillingToPerform (53) Indicates that the server is unwilling to perform the @@ -2477,28 +2455,29 @@ Indicates that the request cannot be fulfilled (added, moved, or renamed) as the target entry already exists. objectClassModsProhibited (69) Indicates that an attempt to modify the object class(es) of an entry's 'objectClass' attribute is prohibited. For example, this code is returned when a client attempts to modify the structural object class of an entry. + Lightweight Directory Access Protocol Version 3 + affectsMultipleDSAs (71) - Indicates that the operation cannot be completed as it - affects multiple servers (DSAs). + Indicates that the operation cannot be performed as it would + affect multiple servers (DSAs). other (80) Indicates the server has encountered an internal error. -Sermersheim Internet-Draft - Expires Aug 2004 Page 45 Lightweight Directory Access Protocol Version 3 Appendix B - Complete ASN.1 Definition This appendix is normative. Lightweight-Directory-Access-Protocol-V3 -- Copyright (C) The Internet Society (2003). This version of -- this ASN.1 module is part of RFC XXXX; see the RFC itself -- for full legal notices. @@ -2541,22 +2520,20 @@ LDAPString ::= OCTET STRING -- UTF-8 encoded, -- [ISO10646] characters LDAPOID ::= OCTET STRING -- Constrained to [Models] LDAPDN ::= LDAPString -- Constrained to -- [LDAPDN] RelativeLDAPDN ::= LDAPString -- Constrained to - -Sermersheim Internet-Draft - Expires Aug 2004 Page 46 Lightweight Directory Access Protocol Version 3 -- [LDAPDN] AttributeDescription ::= LDAPString -- Constrained to -- [Models] AttributeValue ::= OCTET STRING @@ -2599,22 +2576,20 @@ constraintViolation (19), attributeOrValueExists (20), invalidAttributeSyntax (21), -- 22-31 unused -- noSuchObject (32), aliasProblem (33), invalidDNSyntax (34), -- 35 reserved for undefined isLeaf -- aliasDereferencingProblem (36), -- 37-47 unused -- - -Sermersheim Internet-Draft - Expires Aug 2004 Page 47 Lightweight Directory Access Protocol Version 3 inappropriateAuthentication (48), invalidCredentials (49), insufficientAccessRights (50), busy (51), unavailable (52), unwillingToPerform (53), loopDetect (54), -- 55-63 unused -- @@ -2656,22 +2631,20 @@ sasl [3] SaslCredentials, ... } SaslCredentials ::= SEQUENCE { mechanism LDAPString, credentials OCTET STRING OPTIONAL } BindResponse ::= [APPLICATION 1] SEQUENCE { COMPONENTS OF LDAPResult, serverSaslCreds [7] OCTET STRING OPTIONAL } - -Sermersheim Internet-Draft - Expires Aug 2004 Page 48 Lightweight Directory Access Protocol Version 3 UnbindRequest ::= [APPLICATION 2] NULL SearchRequest ::= [APPLICATION 3] SEQUENCE { baseObject LDAPDN, scope ENUMERATED { baseObject (0), singleLevel (1), wholeSubtree (2) }, @@ -2679,23 +2652,23 @@ neverDerefAliases (0), derefInSearching (1), derefFindingBaseObj (2), derefAlways (3) }, sizeLimit INTEGER (0 .. maxInt), timeLimit INTEGER (0 .. maxInt), typesOnly BOOLEAN, filter Filter, attributes AttributeSelection } - AttributeSelection ::= SEQUENCE OF selection LDAPString - -- constrained to - -- in section 4.5.1. + AttributeSelection ::= SEQUENCE OF selector LDAPString + -- The LDAPString is constrained to + -- in Section 4.5.1 Filter ::= CHOICE { and [0] SET SIZE (1..MAX) OF filter Filter, or [1] SET SIZE (1..MAX) OF filter Filter, not [2] Filter, equalityMatch [3] AttributeValueAssertion, substrings [4] SubstringFilter, greaterOrEqual [5] AttributeValueAssertion, lessOrEqual [6] AttributeValueAssertion, present [7] AttributeDescription, @@ -2713,22 +2686,20 @@ MatchingRuleAssertion ::= SEQUENCE { matchingRule [1] MatchingRuleId OPTIONAL, type [2] AttributeDescription OPTIONAL, matchValue [3] AssertionValue, dnAttributes [4] BOOLEAN DEFAULT FALSE } SearchResultEntry ::= [APPLICATION 4] SEQUENCE { objectName LDAPDN, attributes PartialAttributeList } - -Sermersheim Internet-Draft - Expires Aug 2004 Page 49 Lightweight Directory Access Protocol Version 3 PartialAttributeList ::= SEQUENCE OF partialAttribute PartialAttribute SearchResultReference ::= [APPLICATION 19] SEQUENCE SIZE (1..MAX) OF uri URI SearchResultDone ::= [APPLICATION 5] LDAPResult @@ -2771,39 +2742,39 @@ AbandonRequest ::= [APPLICATION 16] MessageID ExtendedRequest ::= [APPLICATION 23] SEQUENCE { requestName [0] LDAPOID, requestValue [1] OCTET STRING OPTIONAL } ExtendedResponse ::= [APPLICATION 24] SEQUENCE { COMPONENTS OF LDAPResult, responseName [10] LDAPOID OPTIONAL, - -Sermersheim Internet-Draft - Expires Aug 2004 Page 50 Lightweight Directory Access Protocol Version 3 responseValue [11] OCTET STRING OPTIONAL } - END + IntermediateResponse ::= [APPLICATION 25] SEQUENCE { + responseName [0] LDAPOID OPTIONAL, + responseValue [1] OCTET STRING OPTIONAL } -Sermersheim Internet-Draft - Expires Aug 2004 Page 51 + END Lightweight Directory Access Protocol Version 3 Appendix C - Changes This appendix is non-normative. This appendix summarizes substantive changes made to RFC 2251 and RFC 2830. -C.1 Changes made to made to RFC 2251: +C.1 Changes made to RFC 2251: This section summarizes the substantive changes made to Sections 1, 2, 3.1, and 4 through the remainder of RFC 2251. Readers should consult [Models] and [AuthMeth] for summaries of changes to other sections. C.1.1 Section 1 - Removed IESG note. Post publication of RFC 2251, mandatory LDAP authentication mechanisms have been standardized which are @@ -2829,21 +2800,20 @@ - There was a mandatory requirement for the server to return a Notice of Disconnection and drop the connection when a PDU is malformed in a certain way. This has been clarified such that the server SHOULD return the Notice of Disconnection, and MUST drop the connection. C.1.5 Section 4.1.1.1 - Clarified that the messageID of requests MUST be non-zero. -Sermersheim Internet-Draft - Expires Aug 2004 Page 52 Lightweight Directory Access Protocol Version 3 - Clarified when it is and isn't appropriate to return an already used message id. RFC 2251 accidentally imposed synchronous server behavior in its wording of this. C.1.6 Section 4.1.2 - Stated that LDAPOID is constrained to from [Models]. @@ -2880,31 +2850,31 @@ C.1.12 Section 4.1.11 - Defined referrals in terms of URIs rather than URLs. - Removed the requirement that all referral URIs MUST be equally capable of progressing the operation. The statement was ambiguous and provided no instructions on how to carry it out. - Added the requirement that clients MUST NOT loop between servers. - Clarified the instructions for using LDAPURLs in referrals, and in doing so added a recommendation that the scope part be present. -Sermersheim Internet-Draft - Expires Aug 2004 Page 53 Lightweight Directory Access Protocol Version 3 C.1.13 Section 4.1.12 - Specified how control values defined in terms of ASN.1 are to be encoded. - Noted that the criticality field is only applied to request messages (except unbindRequest), and must be ignored when present on response messages and unbindRequest. - - Added language regarding combinations of controls on a message. + - Added language regarding combinations of controls and the ordering + of controls on a message. - Changed "The server MUST be prepared" to "Implementations MUST be prepared" in the eighth paragraph to reflect that both client and server implementations must be able to handle this (as both parse controls). C.1.14 Section 4.2 - Mandated that servers return protocolError when the version is not supported. - Clarified behavior when the simple authentication is used, the @@ -2929,22 +2899,20 @@ Each SASL negotiation is, generally, independent of other SASL negotiations. If there were dependencies between multiple negotiations of a particular mechanism, the mechanism technical specification should detail how applications are to deal with them. LDAP should not require any special handling. And if an LDAP client had used such a mechanism, it would have the option of using another mechanism. - Dropped MUST imperative in paragraph 3 to align with [Keywords]. C.1.16 Section 4.2.3 - -Sermersheim Internet-Draft - Expires Aug 2004 Page 54 Lightweight Directory Access Protocol Version 3 - Moved most error-related text to Appendix A, and added text regarding certain errors used in conjunction with the bind operation. - Prohibited the server from specifying serverSaslCreds when not appropriate. C.1.17 Section 4.3 @@ -2981,22 +2949,20 @@ - Recommended that servers not use attribute short names when it knows they are ambiguous or may cause interoperability problems. - Removed all mention of ExtendedResponse due to lack of implementation. C.1.21 Section 4.5.3 - Made changes similar to those made to Section 4.1.11. C.1.22 Section 4.5.3.1 - -Sermersheim Internet-Draft - Expires Aug 2004 Page 55 Lightweight Directory Access Protocol Version 3 - Fixed examples to adhere to changes made to Section 4.5.3. C.1.23 Section 4.6 - Removed restriction that required an EQUALITY matching rule in order to perform value delete modifications. It is sufficiently documented that in absence of an equality matching rule, octet equality is used. @@ -3031,22 +2997,20 @@ added for consistency with other operations and to help ensure data consistency. C.1.27 Section 4.11 - Explained that since abandon returns no response, clients should not use it if they need to know the outcome. - Specified that Abandon and Unbind cannot be abandoned. C.1.28 Section 4.12 - -Sermersheim Internet-Draft - Expires Aug 2004 Page 56 Lightweight Directory Access Protocol Version 3 - Specified how values of extended operations defined in terms of ASN.1 are to be encoded. - Added instructions on what extended operation specifications consist of. - Added a recommendation that servers advertise supported extended operations. C.1.29 Section 5.2 @@ -3068,50 +3032,47 @@ - Noted that servers should protect information equally, whether in an error condition or not, and mentioned specifically; matchedDN, diagnosticMessage, and resultCodes. - Added a note regarding malformed and long encodings. C.1.31 Appendix A - Added "EXTESIBILITY IMPLIED" to ASN.1 definition. - Removed AttributeType. It is not used. -C.2 Changes made to made to RFC 2830: +C.2 Changes made to RFC 2830: This section summarizes the substantive changes made to Sections of RFC 2830. Readers should consult [AuthMeth] for summaries of changes to other sections. C.2.1 Section 2.3 - Removed wording indicating that referrals can be returned from StartTLS - Removed requirement that only a narrow set of result codes can be returned. Some result codes are required in certain scenarios, but any other may be returned if appropriate. C.2.1 Section 4.13.3.1 - -Sermersheim Internet-Draft - Expires Aug 2004 Page 57 Lightweight Directory Access Protocol Version 3 - Reworded most of this section and added the requirement that after the TLS connection has been closed, the server MUST NOT send responses to any request message received before the TLS closure. -C.3 Changes made to made to [LIMR]: +C.3 Changes made to [LIMR]: - In general, all technical language was transferred in whole. Supporting and background language seen as redundant due to its presence in this document was omitted. -Sermersheim Internet-Draft - Expires Aug 2004 Page 58 Lightweight Directory Access Protocol Version 3 Intellectual Property Rights The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on the @@ -3149,12 +3110,10 @@ The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. - -Sermersheim Internet-Draft - Expires Aug 2004 Page 59