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PK G]J�I I F doc/alt-openldap11-devel/drafts/draft-sermersheim-ldap-distproc-xx.txtnu �[��� Network Working Group J. Sermersheim Internet-Draft Novell, Inc Expires: August 26, 2005 February 22, 2005 Distributed Procedures for LDAP Operations draft-sermersheim-ldap-distproc-02.txt Status of this Memo This document is an Internet-Draft and is subject to all provisions of Section 3 of RFC 3667. By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she become aware will be disclosed, in accordance with RFC 3668. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on August 26, 2005. Copyright Notice Copyright (C) The Internet Society (2005). Abstract This document provides the data types and procedures used while servicing Lightweight Directory Access Protocol (LDAP) user operations in order to participate in a distributed directory. In particular, it describes the way in which an LDAP user operation in a distributed directory environment finds its way to the proper DSA(s) for servicing. Sermersheim Expires August 26, 2005 [Page 1] Internet-Draft Distributed Procedures for LDAP Operations February 2005 Discussion Forum Technical discussion of this document will take place on the IETF LDAP Extensions mailing list <ldapext@ietf.org>. Please send editorial comments directly to the author. Table of Contents 1. Distributed Operations Overview . . . . . . . . . . . . . . 3 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Distributed Operation Data Types . . . . . . . . . . . . . . 5 3.1 ContinuationReference . . . . . . . . . . . . . . . . . . . 5 3.2 ChainedRequest . . . . . . . . . . . . . . . . . . . . . . . 9 3.3 Chained Response . . . . . . . . . . . . . . . . . . . . . . 11 4. Distributed Procedures . . . . . . . . . . . . . . . . . . . 14 4.1 Name resolution . . . . . . . . . . . . . . . . . . . . . . 14 4.2 Operation Evaluation . . . . . . . . . . . . . . . . . . . . 16 4.3 Populating the ContinuationReference . . . . . . . . . . . . 19 4.4 Sending a ChainedRequest . . . . . . . . . . . . . . . . . . 21 4.5 Emulating the Sending of a ChainedRequest . . . . . . . . . 23 4.6 Receiving a ChainedRequest . . . . . . . . . . . . . . . . . 24 4.7 Returning a Chained Response . . . . . . . . . . . . . . . . 25 4.8 Receiving a Chained Response . . . . . . . . . . . . . . . . 26 4.9 Returning a Referral or Intermediate Referral . . . . . . . 27 4.10 Acting on a Referral or Intermediate Referral . . . . . . . 30 4.11 Ensuring non-existence of an entry under an nssr . . . . . . 31 4.12 Mapping a referralURI to an LDAP URI . . . . . . . . . . . . 31 4.13 Using the ManageDsaIT control . . . . . . . . . . . . . . . 32 5. Security Considerations . . . . . . . . . . . . . . . . . . 33 6. Normative References . . . . . . . . . . . . . . . . . . . . 33 Author's Address . . . . . . . . . . . . . . . . . . . . . . 34 A. IANA Considerations . . . . . . . . . . . . . . . . . . . . 35 A.1 LDAP Object Identifier Registrations . . . . . . . . . . . . 35 A.2 LDAP Protocol Mechanism Registrations . . . . . . . . . . . 35 A.3 LDAP Descriptor Registrations . . . . . . . . . . . . . . . 37 A.4 LDAP Result Code Registrations . . . . . . . . . . . . . . . 38 Intellectual Property and Copyright Statements . . . . . . . 39 Sermersheim Expires August 26, 2005 [Page 2] Internet-Draft Distributed Procedures for LDAP Operations February 2005 1. Distributed Operations Overview One characteristic of X.500-based directory systems [X500] is that, given a distributed Directory Information Tree (DIT), a user should potentially be able to have any service request satisfied (subject to security, access control, and administrative policies) irrespective of the Directory Service Agent (DSA) to which the request was sent. To accommodate this requirement, it is necessary that any DSA involved in satisfying a particular service request have some knowledge (as specified in {TODO: Link to future Distributed Data Model doc}) of where the requested information is located and either return this knowledge to the requester or attempt to satisfy the request satisfied on the behalf of the requester (the requester may either be a Directory User Agent (DUA) or another DSA). Two modes of operation distribution are defined to meet these requirements, namely "chaining" and "returning referrals". "Chaining" refers to the attempt by a DSA to satisfy a request by sending one or more chained operations to other DSAs. "Returning referrals", is the act of returning distributed knowledge information to the requester, which may then itself interact with the DSA(s) identified by the distributed knowledge information. It is a goal of this document to provide the same level of service whether the chaining or referral mechanism is used to distribute an operation. The processing of an operation is talked about in two major phases, namely "name resolution", and "operation evaluation". Name resolution is the act of locating a local DSE held on a DSA given a distinguished name (DN). Operation evaluation is the act of performing the operation after the name resolution phase is complete. While distributing an operation, a request operation may be decomposed into several sub-operations. The distributed directory operation procedures described in this document assume the absense of the ManageDsaIT control defined in [RFC3296] and described in Section 4.13. Sermersheim Expires August 26, 2005 [Page 3] Internet-Draft Distributed Procedures for LDAP Operations February 2005 2. Conventions Imperative keywords defined in [RFC2119] are used in this document, and carry the meanings described there. All Basic Encoding Rules (BER) [X690] encodings follow the conventions found in Section 5.1 of [RFC2251]. Sermersheim Expires August 26, 2005 [Page 4] Internet-Draft Distributed Procedures for LDAP Operations February 2005 3. Distributed Operation Data Types The data types in this section are used by the chaining and referral distributed operation mechanisms described in Section 4 3.1 ContinuationReference As an operation is being processed by a DSA, it is useful to group the information passed between various procedures as a collection of data. The ContinuationReference data type is introduced for this purpose. This data type is populated and consumed by various procedures discussed in various sections of this document. In general, a ContinuationReference is used when indicating that directory information being acted on is not present locally, but may be present elsewhere. A ContinuationReference consists of one or more addresses which identify remote DSAs along with other information pertaining both to the distributed knowledge information held on the local DSA as well as information relevant to the operation. This data type is expressed here in Abstract Syntax Notation One (ASN.1) [X680]. ContinuationReference ::= SET { referralURI [0] SET SIZE (1..MAX) OF URI, localReference [2] LDAPDN, referenceType [3] ReferenceType, remainingName [4] RelativeLDAPDN OPTIONAL, searchScope [5] SearchScope OPTIONAL, searchedSubtrees [6] SearchedSubtrees OPTIONAL, failedName [7] LDAPDN OPTIONAL, ... } <Editor's Note: Planned for addition is a searchCriteria field which is used both for assuring that the remote object is in fact the object originally pointed to (this mechanism provides a security measure), and also to allow moved or renamed remote entries to be found. Typically the search criteria would have a filter value of (entryUUID=<something>)> URI ::= LDAPString -- limited to characters permitted in URIs [RFC2396]. ReferenceType ::= ENUMERATED { superior (0), subordinate (1), cross (2), nonSpecificSubordinate (3), Sermersheim Expires August 26, 2005 [Page 5] Internet-Draft Distributed Procedures for LDAP Operations February 2005 suplier (4), master (5), immediateSuperior (6), self (7), ... } SearchScope ::= ENUMERATED { baseObject (0), singleLevel (1), wholeSubtree (2), subordinateSubtree (3), ... } SearchedSubtrees ::= SET OF RelativeLDAPDN LDAPDN, RelativeLDAPDN, and LDAPString, are defined in [RFC2251]. The following subsections introduce the fields of the ContinuationReference data type, but do not provide in-depth semantics or instructions on the population and consumption of the fields. These topics are discussed as part of the procedural instructions. 3.1.1 ContinuationReference.referralURI The list of referralURI values is used by the receiver to progress the operation. Each value specifies (at minimum) the protocol and address of one or more remote DSA(s) holding the data sought after. URI values which are placed in ContinuationReference.referralURI must allow for certain elements of data to be conveyed. Section 3.1.1.1 describes these data elements. Furthermore, a mapping must exist which relates the parts of a specified URI to these data elements. This document provides such a mapping for the LDAP URL [RFC2255] in Section 4.12. In some cases, a referralURI will contain data which has a counterpart in the fields of the ContinuationReference (an example is where the referralURI is an LDAP URL, holds a <scope> value, and the ContinuationReference.searchScope field is also present). In these cases, the data held on the referralURI overrides the field in the ContinuationReference. Specific examples of this are highlighted in other sections. Providing a means for these values to exist as fields of the ContinuationReference allows one value to be applied to all values of referralURI (as opposed to populating duplicate data on all referralURI values). If a referralURI value identifies an LDAP-enabled DSA [RFC3377], the LDAP URL form is used. Sermersheim Expires August 26, 2005 [Page 6] Internet-Draft Distributed Procedures for LDAP Operations February 2005 3.1.1.1 Elements of referralURI Values The following data elements must be allowed and identified for a specified URI type to be used to convey referral information. Each element is given a name which begins with 'referralURI.' for clarity when referencing the elements conceptually in other parts of this document. o referralURI.protocolIdentifier. There must be an indication of the protocol to be used to contact the DSA identified by the URI. o referralURI.accessPoint. The URI must identify a DSA in a manner that can be used to contact it using the protocol specified in protocolIdentifier. o referralURI.targetObject. Holds the name to be used as the base DN of the operation being progressed. This field must be allowed by the URI specification, but may be omitted in URI instances for various reasons. o referralURI.localReference. See Section 3.1.2. This field must be allowed by the URI specification, but may be omitted in URI instances for various reasons. o referralURI.searchScope. See Section 3.1.5. This field must be allowed by the URI specification, but may be omitted in URI instances for various reasons. o referralURI.searchedSubtrees. See Section 3.1.6. This field must be allowed by the URI specification, but may be omitted in URI instances for various reasons. o referralURI.failedName. See Section 3.1.7. This field must be allowed by the URI specification, but may be omitted in URI instances for various reasons. 3.1.2 ContinuationReference.localReference This names the DSE which was found to hold distributed knowledge information, and thus which caused the ContinuationReference to be formed. This field is primarily used to help convey the new target object name, but may also be used for purposes referential integrity (not discussed here). In the event that the root object holds the distributed knowledge information, this field is present and is populated with an empty DN. 3.1.3 ContinuationReference.referenceType Indicates the DSE Type of the ContinuationReference.localReference. This field may be used to determine how to progress an operations (i.e. if the value is nonSpecificSubordinate, a search continuation will exclude the ContinuationReference.referenceType). Sermersheim Expires August 26, 2005 [Page 7] Internet-Draft Distributed Procedures for LDAP Operations February 2005 3.1.4 ContinuationReference.remainingName In certain scenarios, the localReference does not completely name the DSE to be used as the new target object name. In these cases, remainingName is populated with the RDNSequence relative to the localReference of the target object name being resolved. Some examples of these scenarios include (but are not restricted to): o During name resolution, the name is not fully resolved, but a DSE holding distributed knowledge information is found, causing a ContinuationReference to be generated. o While searching, an alias is dereferenced. The aliasedObjectName points to a DSE of type glue which is subordinate to a DSE holding distributed knowledge information. 3.1.5 ContinuationReference.searchScope Under certain circumstances, when progressing a search operation, a search scope different than that of the original search request must be used. This field facilitates the conveyance of the proper search scope to be used when progressing the distributed operation. The scope of subordinateSubtree has been added to the values allowed by the LDAP SearchRequest.scope field. This scope includes the subtree of entries below the base DN, but does not include the base DN itself. This is used here when progressing distributed search operations caused by the existence of a DSE of type nssr. If a referralURI.searchScope is present, it overrides this field while that referralURI is being operated upon. 3.1.6 ContinuationReference.searchedSubtrees For ContinuationReferences generated while processing a search operation with a scope of wholeSubtree, each value of this field indicates that a particular subtree below the target object has already been searched. Consumers of this data use it to cause the progression of the search operation to exclude these subtrees as a mechanism to avoid receiving duplicate entries. If a referralURI.searchedSubtrees is present, it overrides this field while that referralURI is being operated upon. 3.1.7 ContinuationReference.failedName When an operation requires that multiple names be resolved (as is the case with the ModifyDN operation), this field is used to specify which name was found to be non-local. Sermersheim Expires August 26, 2005 [Page 8] Internet-Draft Distributed Procedures for LDAP Operations February 2005 If a referralURI.failedName is present, it overrides this field while that referralURI is being operated upon. 3.2 ChainedRequest The Chained Request is sent as an LDAP extended operation. The requestName is IANA-ASSIGNED-OID.1. The requestValue is the BER encoding of the following ChainedRequestValue ASN.1 definition: ChainedRequestValue ::= SEQUENCE { chainingArguments ChainingArguments, operationRequest OperationRequest } ChainingArguments ::= SEQUENCE { targetObject [0] LDAPDN OPTIONAL, referenceType [1] ReferenceType, traceInformation [2] ChainingTraceInformation, searchScope [3] SearchScope OPTIONAL, searchedSubtrees [4] SearchedSubtrees OPTIONAL} ChainingTraceInformation ::= SET OF LDAPURL OperationRequest ::= SEQUENCE { Request ::= CHOICE { bindRequest BindRequest, searchRequest SearchRequest, modifyRequest ModifyRequest, addRequest AddRequest, delRequest DelRequest, modDNRequest ModifyDNRequest, compareRequest CompareRequest, extendedReq ExtendedRequest, ... }, controls [0] Controls COPTIONAL } BindRequest, SearchRequest, ModifyRequest, AddRequest, DelRequest, ModifyDNRequest, CompareRequest, ExtendedRequest and Controls are defined in [RFC2251]. 3.2.1 ChainedRequestValue.chainingArguments In general, these fields assist in refining the original operation as it is to be executed on the receiving DSA. Sermersheim Expires August 26, 2005 [Page 9] Internet-Draft Distributed Procedures for LDAP Operations February 2005 3.2.1.1 ChainedRequestValue.chainingArguments.targetObject This field contains the new target (or base) DN for the operation. The sending DSA populates this under different scenarios including the case where an alias has been dereferenced while resolving the DN, and also the case where a referral carries a target name different from the reference object that caused the referral. This field can be omitted only if it would be the the same value as the object or base object parameter in the ChainedRequestValue.operationRequest, in which case its implied value is that value. The receiving DSA examines this field and (if present) uses it rather than the base DN held in the ChainedRequestValue.operationRequest. 3.2.1.2 ChainedRequestValue.chainingArguments.referenceType See Section 3.1.3. If the receiver encounters a value of nonSpecificSubordinate in this field, it indicates that the operation is being chained due to DSE of type nssr. In this case, the receiver allows (and expects) the base DN to name the immediate superior of a context prefix. 3.2.1.3 ChainedRequestValue.chainingArguments.traceInformation This contains a set of URIs. Each value represents the address of a DSA and DN that has already been contacted while attempting to service the operation. This field is used to detect looping while servicing a distributed operation. The sending DSA populates this with its own URI, and also the URIs of any DSAs that have already been chained to. The receiving DSA examines this list of URIs and returns a loopDetect error if it finds that any of the addresses and DNs in the listed URI's represent it's own. 3.2.1.4 ChainedRequestValue.chainingArguments.searchScope See Section 3.1.5. 3.2.1.5 ChainedRequestValue.chainingArguments.searchedSubtrees See Section 3.1.6. Sermersheim Expires August 26, 2005 [Page 10] Internet-Draft Distributed Procedures for LDAP Operations February 2005 3.2.2 ChainedRequestValue.operationRequest This holds the original LDAP operation request. This is restricted to a subset of all LDAP operations. Namely, the following LDAP operation types are not allowed: o Abandon/Cancel operations. When an abandon or cancel operation needs to be chained, it is sent to the remote DSA as-is. This is because there is no need to track it for loop detection or pass on any other information normally found in ChainingArguments. o Unbind. Again, there is no need to send chaining-related information to a DSA to perform an unbind. DSAs which chain operations maintain connections as they see fit. o Chained Operation. When a DSA receives a chained operation, and must again chain that operation to a remote DSA, it sends a ChainedRequest where the ChainedRequestValue.operationRequest is that of the incoming ChainedRequestValue.operationRequest. 3.3 Chained Response The Chained Response is sent as an LDAP IntermediateResponse [RFC3771], or LDAP ExtendedResponse [RFC2251], depending on whether the operation is complete or not. In either case, the responseName is omitted. For intermediate responses, the IntermediateResponse.responseValue is the BER encoding of the ChainedIntermediateResponseValue ASN.1 definition. For completed operations, the ExtendedResponse.value is the BER encoding of the ChainedFinalResponseValue ASN.1 definition. ChainedIntermediateResponseValue ::= SEQUENCE { chainedResults ChainingResults, operationResponse IntermediateResponse } ChainedFinalResponseValue ::= SEQUENCE { chainedResults ChainingResults, operationResponse FinalResponse } ChainingResults ::= SEQUENCE { searchedSubtrees [0] SearchedSubtrees OPTIONAL, ... } IntermediateResponse ::= SEQUENCE { Response ::= CHOICE { Sermersheim Expires August 26, 2005 [Page 11] Internet-Draft Distributed Procedures for LDAP Operations February 2005 searchResEntry SearchResultEntry, searchResRef SearchResultReference, intermediateResponse IntermediateResponse ... }, controls [0] Controls COPTIONAL } FinalResponse ::= SEQUENCE { Response ::= CHOICE { bindResponse BindResponse, searchResDone SearchResultDone, modifyResponse ModifyResponse, addResponse AddResponse, delResponse DelResponse, modDNResponse ModifyDNResponse, compareResponse CompareResponse, extendedResp ExtendedResponse, ... }, controls [0] Controls COPTIONAL } BindResponse, SearchResultEntry, SearchResultDone, SearchResultReference, ModifyResponse, AddResponse, DelResponse, ModifyDNResponse, CompareResponse, ExtendedResponse, and Controls are defined in [RFC2251]. IntermediateResponse is defined in [RFC3771]. 3.3.1 ChainingResults In general, this is used to convey additional information that may needed in the event that the operation needs to be progressed further. 3.3.1.1 ChainingResults.searchedSubtrees Each value of this field indicates that a particular subtree below the target object has already been searched. This is particularly useful while chaining search operations during operation evaluation caused by the presence of a DSA of type nssr. Each DSA referenced by the nssr holds one or more naming contexts subordinate to the nssr DSE. The ChainingResults.searchedSubtrees field allows the DSA being chained to, to inform the sending DSA which subordinate naming contexts have been searched. This information may be passed to further DSAs listed on the nssr in order to reduce the possibility of duplicate entries being returned. Sermersheim Expires August 26, 2005 [Page 12] Internet-Draft Distributed Procedures for LDAP Operations February 2005 3.3.2 ChainedIntermediateResponseValue.intermediateResponse and ChainedFinalResponseValue.finalResponse This holds the directory operation response message tied to the ChainedRequestValue.operationRequest. Sermersheim Expires August 26, 2005 [Page 13] Internet-Draft Distributed Procedures for LDAP Operations February 2005 4. Distributed Procedures For the purposes of describing a distributed operation, operations are said to consist of two major phases -- name resolution and operation evaluation. These terms are adopted from [X518]. Name resolution is the act of locating a DSE said to be held locally by a DSA given a distinguished name (DN). Operation evaluation is the act of performing the operation after the name resolution phase is complete. Furthermore, there are two modes of distributing an operation -- chaining, and returning referrals. Chaining is the act of forwarding an unfinished operation to another DSA for completion (this may happen during name resolution or operation evaluation). In this case, the forwarding DSA sends a chained operation to a receiving DSA, which attempts to complete the operation. Alternately, the DSA may return a referral (or intermediate referral), and the client may use that referral in order to forward the unfinished operation to another DSA. Whether the operation is distributed via chaining or referrals is a decision left to the DSA and or DUA. The term 'intermediate referral' describes a referral returned during the operation evaluation phase of an operation. These include searchResultReferences, referrals returned with an intermediateResponse [RFC3771], or future referrals which indicate that they are intermediate referrals. An operation which is distributed while in the operation evaluation phase is termed a 'sub-operation'. This document inserts a step between the two distributed operation phases in order to commonize the data and processes followed prior to chaining an operation or returning a referral. This step consists of populating a ContinuationReference data type. 4.1 Name resolution Before evaluating (enacting) most directory operations, the DSE named by the target (often called the base DN) of the operation must be located . This is done by evaluating the RDNs of the target DN one at a time, starting at the rootmost RDN. Each RDN is compared to the DSEs held by the DSA until the set of RDNs is exhausted, or an RDN cannot be found. If the DSE named by the target is found to be local, the name resolution phase of the operation completes and the operation evaluation phase begins. Sermersheim Expires August 26, 2005 [Page 14] Internet-Draft Distributed Procedures for LDAP Operations February 2005 If it is found that the target does not name a local DSE nor a DSE that may held by another DSA, it is said that the target does not exist, and the operation fails with noSuchObject (subject to local policy). If it is found that the DSE named by the target is non-local to the DSA, but may reside elsewhere, name resolution is said to be incomplete. In this case, the operation may be distributed by creating a ContinuationReference (Section 4.3) and either chaining the operation (Section 4.4 and Section 4.5)or returning a referral (Section 4.9). 4.1.1 Determining that a named DSE is local to a DSA If a DSE held by a DSA falls within a naming context held by the DSA, or is the root DSE on a first-level DSA, it is said to be local to that DSA 4.1.2 Determining that a named DSE does not exist A named DSE is said to not exist if, during name resolution the DSE is not found, but if found it would fall within a naming context held by the DSA. 4.1.3 Determining that a named DSE is non-local If a named DSE is niether found to be local to the DSA, nor found to not exist, it is said to be non-local to a DSA. In this case, it is indeterminate whether the named DSE exists. When a named DSE is found to be non-local, there should be distributed knowledge information available to be used to either return a referral or chain the operation. 4.1.3.1 Locating distributed knowledge information for a non-local target If it has been determined that a target names a non-local DSE, distributed knowledge information may be found by first examining the DSE named by the target, and subsequently all superior DSEs beginning with the immediate superior and ending with the root, until an examined DSE is one of types: {TODO: should DSE types be all caps? It would be easier to read.} o subr o supr o immsupr Sermersheim Expires August 26, 2005 [Page 15] Internet-Draft Distributed Procedures for LDAP Operations February 2005 o xr o nssr The examined DSE which is of one of these types holds the distributed knowledge information for the non-local named target. This DSE is said to be the found distributed knowledge information of the non-local target. This found distributed knowledge information may then be used to distribute the operation. If no examined DSEs are of any of these types, the distributed knowledge information is mis-configured, and the error invalidReference is returned. 4.1.4 Special case for the Add operation During the name resolution phase of the Add operation, the immediate parent of the base DN is resolved. If the immediate parent of the entry to be added is a DSE of type nssr, then further interrogation is needed to ensure that the entry to be added does not exist. Methods for doing this are found in Section 4.11. {TODO: don't make this mandatory. Also, it doesn't work without transaction semantics. Same prob in the mod dn below.}. 4.1.5 Special case for the ModifyDN operation When the modifyDN operation includes a newSuperior name, it must be resolved as well as the base DN being modified. If either of these result in a non-local name, the name causing the operation to be distributed should be conveyed (Section 4.3.5). {TODO: also mention access control problems, and mention (impl detail) that affectsmultidsa can be used.} If during operation evaluation of a ModifyDN operation, the newSuperior names a DSE type of nssr, then further interrogation is needed to ensure that the entry to be added does not exist. Methods for doing this are found in Section 4.11. 4.2 Operation Evaluation Once name resolution has completed. The DSE named in the target has been found to be local to a DSA. At this point the operation can be carried out. During operation evaluation distributed knowledge information may be found that may cause the DSA to distribute the operation. When this happens, the operation may be distributed by creating a ContinuationReference (Section 4.3) and either chaining the operation (Section 4.4 and Section 4.5)or returning a referral (Section 4.9). Sermersheim Expires August 26, 2005 [Page 16] Internet-Draft Distributed Procedures for LDAP Operations February 2005 If, during the location of the distributed knowledge information, the distributed knowledge information is found to be mis-configured, operation semantics are followed (some operations may call for an error to be returned, while others call for the error to be ignored). {TODO: either make this more specific, or less specific, or just toss it out.} 4.2.1 Search operation During operation evaluation of a search operation, the DSA must determine whether there is distributed knowledge information in the scope of the search. Any DSE in the search scope which is of the following types is considered to be 'found distributed knowledge information' {TODO: use a better term than found distributed knowledge information} in the search scope: o subr o nssr (see nssr note) o xr {TODO: I think xr only qualifies when an alias is dereferenced to an xr. Otherwisw, there should always be a subr above the xr if it falls in the search scope.} Note that due to alias dereferencing, the search scope may expand to include entries outside of the scope originally specified in the search operation. {TODO: note that an aliased object may be glue which needs to result in any subr or xr above it to be found} Nssr Note: A DSE of type nssr is only considered to be found distributed knowledge information when the scope of the search includes entries below it. For example, when the search scope is wholeSubtree or subordinateSubtree and a DSE of type nssr is found in the scope, or if the search scope is singleLevel and the target object names a DSE of type nsssr. {TODO: The following sections are talking about how the continuation reference is to be populated. Move to next secion. Can probably just say that whole subtree or subordinare subtree encountering nssr, and single level rooted at nssr result in a continuation reference. base at, and single level above do not result in a continuation reference.} 4.2.1.1 Search operation with singleLevel scope If distributed knowledge information is found during operation evaluation of a search with a singleLevel scope, it will cause the resulting ContinuationReference.searchScope to be set to baseObject. Sermersheim Expires August 26, 2005 [Page 17] Internet-Draft Distributed Procedures for LDAP Operations February 2005 4.2.1.2 Search operation encountering nssr knowledge reference When a search operation encounters distributed knowledge information which is a DSE type of nssr during operation evaluation, the following instructions are followed: Note that when a search operation is being progressed due to nssr knowledge information, the subsequent distributed progression of the search is caused to be applied to each DSA listed as non-specific knowledge information (This is talked about in Section 4.3.2). In the event that multiple DSAs listed in the knowledge information hold copies of the same directory entries, the 'already searched' and 'duplicate elimination' mechanisms SHOULD be used to prevent duplicate search result entries from ultimately being returned. 4.2.1.2.1 wholeSubtree search scope When the search scope is wholeSubtree, the ContinuationReference.searchScope is set to subordinateSubtree. Because the ContinuationReference.referrenceType is set to nonSpecificSubordinate, the receiving protocol peer allows (and expects) name resolution to stop at an immsupr DSE type which is treated as a local DSE. The subordinateSubtree scope instructs the receiving protocol peer to exclude the target object from the sub-search. 4.2.1.2.2 singleLevel search scope When the search scope is singleLevel, and the base DN is resolved to a DSE of type nssr, subsequent distributed progressions of the search are caused to use the same base DN, and a scope of singleLevel. Receiving protocol peers will only apply the search to entries below the target object. When the search scope is singleLevel and an evaluated DSE is of type nssr, no special handling is required. The search is applied to that DSE if it is of type entry. 4.2.1.2.3 baseObject search scope No special handling is needed when the search scope is baseObject and the base DN is an nssr DSEType. The search is applied to that DSE if it is of type entry. 4.2.1.3 Search operation rooted at an nssr DSE type (TODO: a subordinateSubtree scope needs to change to wholeSubtree if references are found.) Sermersheim Expires August 26, 2005 [Page 18] Internet-Draft Distributed Procedures for LDAP Operations February 2005 4.3 Populating the ContinuationReference When an entry is found to be non-local to a DSA (whether during name resolution or operation evaluation), the DSA prepares for operation distribution by generating a ContinuationReference. This is a conceptual step, given to help explain the interactions that occur between discovering that an operation must be distributing, and actually invoking the operation distribution mechanism. Implementations are not required to perform this step, but will effectively work with the same information. After the ContinuationReference has been created, the DSA may choose to chain the operation or return a referral (or intermediate referral(s)). the ContinuationReference is made up of data held on the found distributed knowledge information, as well as state information gained during name resolution or operation evaluation. 4.3.1 Conveying the Target Object The consumer of the ContinuationReference will examine various fields in order to determine the target object name of the operation being progressed. The fields examined are the localReference and remainingName. If name resolution did not complete, and the found distributed knowledge information names the same DSE as the base DN of the operation, the ContinuationReference MAY omit the localReference and/or remainingName fields. localReference is populated with the name of the found distributed knowledge information DSE. In the event that the root object holds the distributed knowledge information, this field will be populated with an empty DN. Contrast this with the omission of this field. referenceType is populated with a value reflecting the reference type of the localReference DSE. remainingName is populated with the RDNSequence which has not yet been resolved. This is the difference between the localReference value and the name of the DSE to be resolved. In cases where the DSE named by the {TODO, use a dash or different term to make 'found distributed knowledge' more like a single term} found distributed knowledge is not the same as the base DN of the operation, the ContinuationReference must contain the localReference and/or remainingName fields. Such cases include but are not limited Sermersheim Expires August 26, 2005 [Page 19] Internet-Draft Distributed Procedures for LDAP Operations February 2005 to: o Distributed knowledge information is found during operation evaluation. o Aliases were dereferenced during name resolution. o Name resolution did not complete and there were remaining RDNs to be resolved. 4.3.2 Conveying the Remote DSA The referralURI field must contain at least one value. Each referralURI value must hold a referralURI.accessPoint. Other requirements on this field as noted may also apply. Note for nssr DSE types: During operation evaluation, if a DSE of type nssr causes the operation to be distributed (the scenarios in Section 4.2.1.2 are an example), then an intermediate referral {TODO: this is talking about referral/intermediate referral, but this section is only dealing with populating continuation reference} is returned for each value of the ref attribute, where each intermediate referral only holds a single referralURI value. 4.3.3 Conveying new search scope During the evaluation of the search operation, the instructions in Section 4.2.1.2.1 and Section 4.2.1.2.2 are followed and the searchScope field is updated with the new search scope. 4.3.4 Preventing duplicates In order to prevent duplicate entries from being evaluated while progressing a search operation, the searchedSubtrees field is populated with any naming context below the ContinuationReference.targetObject which have been fully searched. During the evaluation of the search operation, if the scope is wholeSubtree, it is possible that the DSA may search the contents of a naming context which is subordinate to another naming context which is subordinate to the search base (See figure). Sermersheim Expires August 26, 2005 [Page 20] Internet-Draft Distributed Procedures for LDAP Operations February 2005 O X / \ / \ / \ / \ \_______O Y /|\ / | \ / | \ / | \ A B O C / \ / \ / \ / \ \_______/ In this figure, the DSA holds the naming context X and C,Y,X, but not Y,X. If the search base was X, an intermediate referral would be returned for Y,X. The DSA holding Y,X may also hold a copy of C,Y,X. In this case, the receiver of the ContinuationReference benefits by knowing that the DSA already searched C,Y,X so that it can prevent other DSAs from returning those entries again. Data already searched is in the form of an RDNSequence, consisting of the RDNs relative to the target object. 4.3.5 Conveying the Failed Name At least one DS operation (modifyDN) requires that multiple DNs be resolved (the entry being modified and the newSuperior entry). In this case, the failedName field will be populated with the DN being resolved which failed name resolution. This may aid in the determination of how the operation is to be progressed. If both names are found to be non-local, this field is omitted. 4.4 Sending a ChainedRequest When an entry is found to be non-local to a DSA (whether during name resolution or operation evaluation), the DSA may progress the operation by sending a chained operation to another DSA (or DSAs). The instructions in this section assume that a ContinuationReference has been generated which will be used to form the ChainedRequest. It is also assumed that it can be determined whether the operation is being progressed due to name resolution or due to operation evaluation. A DSA which is able to chain operations may advertise this by Sermersheim Expires August 26, 2005 [Page 21] Internet-Draft Distributed Procedures for LDAP Operations February 2005 returning a value of IANA-ASSIGNED-OID.2; in the supportedFeatures attribute on the root DSE. {TODO: does this and discovery of the extended op belong in a new 'discovery mechanisms' sections.} 4.4.1 Forming a ChainedRequest The following fields are populated as instructed: 4.4.1.1 ChainedRequestValue.chainingArguments.targetObject The ContinuationReference may convey a new target object. If present, the ContinuationReference.localReference field becomes the candidate target object. Otherwise the candidate target object is assumed to be that of the original directory operation. Note that an empty value in the ContinuationReference.localReference field denotes the root object. After performing the above determination as to the candidate target object, any RDNSequence in ContinuationReference.remainingName is prepended to the determined candidate target object. This value becomes the ChainedRequestValue.chainingArguments.targetObject. If this value matches the value of the original operation, this field may be omitted. 4.4.1.2 ChainedRequestValue.chainingArguments.referenceType This is populated with the ContinuationReference.referralURI.referenceType. 4.4.1.3 ChainedRequestValue.chainingArguments.traceInformation This is populated as specified in Section 3.2.1.3. 4.4.1.4 ChainedRequestValue.chainingArguments.searchScope This is populated with the ContinuationReference.referralURI.searchScope if present, otherwise by the ContinuationReference.searchScope if present, and not populated otherwise. 4.4.1.5 ChainedRequestValue.chainingArguments.searchedSubtrees This is populated with ContinuationReference.searchedSubtrees, as well as any previously received values of ChainedFinalResponseValue.chainingResults.searchedSubtrees or ChainedIntermediateResponseValue.chainingResults.searchedSubtrees which are subordinate, relative to the target object. (If thsi is relative to the target object, it can't contain non-relative Sermersheim Expires August 26, 2005 [Page 22] Internet-Draft Distributed Procedures for LDAP Operations February 2005 subtrees) 4.4.1.6 ChainedRequestValue.operationRequest This is populated with the original directory operation request. 4.4.2 Attempting Each Referral URI A ContinuationReference consists of one or more referralURIs which represent(s a) remote DSA(s). The chaining DSA attempts to chain to each of these DSAs until one succeeds in completing the operation. An operation is considered to be completed if it reaches the remote DSA and a response is sent back that indicates that the operation was executed. Operations which are sent to the remote DSA, but don't complete are indicated by a result code of unavailable or busy. A result code of protocolError may indicate that the DSA does not support the chained operation, and in this case, it is also treated as an uncompleted operation. Other errors may in the future specify that they also indicate non-completion. Note that the response may itself contain referral(s), these are still considered completed operations and thus would subsequently be handled and chained. {TODO: could use soft/hard, or transient/permanent referral/non-referral error terms here.} 4.4.3 Loop Prevention Prior to sending a ChainedRequest, the DSA may attempt to prevent looping scenarios by comparing {TODO: what matching rule is used? Suggest we don't convert dns names to ip addresses due to NATs} the address of the remote DSA and target object to the values of ChainedRequestValue.chainingArguments.traceInformation. If a match is found, the DSA returns a loopDetect error. Note that while this type of loop prevention aids in detecting loops prior to sending data to a remote DSA, it is not a substitute for loop detection (Section Section 4.6.2). This is because the sending DSA is only aware of a single address on which the receiving DSA accepts connections. 4.5 Emulating the Sending of a ChainedRequest When it is determined that the operation cannot be distributed by means of the ChainedRequest, the chaining DSA may instead emulate the steps involved in chaining the operation. These steps consist of performing loop prevention, forming a new directory operation request from the original request and possibly updating the base DN, search scope, and search filter(in order to emulate searchedSubtrees), and, similar to the steps in Section 4.4.2, attempting to send the operation request to each DSA listed in the ContinuationReference.referralURI until one succeeds in completing Sermersheim Expires August 26, 2005 [Page 23] Internet-Draft Distributed Procedures for LDAP Operations February 2005 the operation. {TODO: We need a way (control) to tell the receiver to allow name resolution to end on the parent of a cp (typically an immsupr). This would be sent when the ContinuationReference.referenceType is nonSpecificSubordinate} 4.5.1 Emulated Loop Detection For this step, the loop prevention instructions in Section 4.4.3 are followed. Note that this method of loop detection may actually allow some looping to occur before the loop is detected. 4.5.2 Forming the New Request The new directory operation request is formed from the fields of the original request, and the following fields may be updated: o The base DN is formed from the new target object as determined by following the instructions in Section 4.4.1.1 and using the value which would have been placed in ChainedRequestValue.chainingArguments.targetObject. o For the search operation, the scope is populated with ContinuationReference.searchScope if present, otherwise the scope of the original operation request is used. o For the search operation, if the ContinuationReference.searchedSubtrees field is present, causes the search filter to be augmented by adding a filter item of the 'and' CHOICE. The filter consists of {TODO: weasel Kurt into finishing his entryDN draft and reference the appropriate section there. See <http://www.openldap.org/lists/ietf-ldapext/200407/msg00000.html> for context} o Other fields (such as the messageID, and non-critical controls) may also need to be updated or excluded. If the service being chained to does not support directory operations, other operations may be used as long as they provide the same level as service as those provided by the analogous directory operation. 4.6 Receiving a ChainedRequest A DSA which is able to receive and service a ChainedRequest may advertise this feature by returning a value of IANA-ASSIGNED-OID.1 in the supportedExtension attribute of the root DSE. {TODO: move?} The ChainedRequestValue data type is the requestValue of an Sermersheim Expires August 26, 2005 [Page 24] Internet-Draft Distributed Procedures for LDAP Operations February 2005 extendedRequest. In general, receiving and servicing a ChainedRequest consists of performing loop detection and, using components of the ChainedRequestType.chainingArguments along with the ChainedRequestType.operationRequest, service the request. 4.6.1 Target Object determination Prior to checking for a loop condition, the target object must be determined. If the ChainedRequestType.chainingArguments.targetObject field is present, its value becomes the target object. Otherwise, the base DN found in the ChainedRequestType.operationRequest becomes the target object. 4.6.2 Loop Detection The loop detection check happens when a DSA receives a chained operation, prior to acting on the operation. The DSA compares {TODO: matching rule? DNS expansion?} each value of ChainedRequestValue.traceInformation to the list of addresses at which it accepts directory communications. A value of ChainedRequestValue.traceInformation matches when the DSA accepts directory communications on the address found in the ChainedRequestValue.traceInformation value, and the target object (as determined in Section 4.6.1 matches the DN {TODO: using DN matching?} value found in the ChainedRequestValue.traceInformation value. If a match is found the DSA returns a loopDetect result. 4.6.3 Processing the ChainedRequestValue.operationRequest In processing the operationRequest, the DSA uses the target object determined in Section 4.6.1. For search operations, it uses the scope found in ChainedRequestValue.chainingArguments.searchScope, and excludes any subtrees relative to the target object indicated in ChainedRequestValue.chainingArguments.searchedSubtrees. Responses are returned in the form of a Chained Response. 4.7 Returning a Chained Response When returning responses to a ChainedRequest, the Chained Response as documented in Section 3.3 is used. If the ChainedFinalResponseValue.operationResponse is a searchResultDone, the ChainedFinalResponseValue.chainingResults.searchedSubtrees field is populated with values consisting of the RDNSequence relative to the target object of naming contexts that the DSA searched. See Section 3.3.1.1 for details on why this is done. Sermersheim Expires August 26, 2005 [Page 25] Internet-Draft Distributed Procedures for LDAP Operations February 2005 4.7.1 Chained Response resultCode The resultCode for the Chained Response is distinct from the result code of the ChainedIntermediateResponseValue.intermediateResponse or ChainedFinalResponseValue.finalResponse. If the act of chaining the operation completed, then this value will be success. Other result codes refer to the chained operation itself, and not the result of the embedded operation. 4.7.2 Returning referrals in the Chained Response {TODO: it would be less complicated if rather than using the simple LDAP URL, we used the ContinuationReference type to return referrals and intermediate referrals.} {TODO: We need an example of why we should allow referrals on a chained response. Why not just use the referral field in the operation?} 4.8 Receiving a Chained Response Processing a received Chained Response is generally straight forward -- typically the response is simply extracted and returned, but there are some extra steps to be taken when chaining sub-operations. 4.8.1 Handling Sub-operation controls and result codes When sub-operations are chained, there is the possibility that different result codes will be encountered. Similarly, if controls which elicit response controls were attached to the operation, it's possible that multiple response controls will be encountered. Both of these possibilities require that the chaining DSA take appropriate steps to ensure that the response being returned is correct. In general, when a result code indicating an error is received, the operation will terminate and the error will be returned. In cases where multiple sub-operations are being concurrently serviced, the operation will terminate and the most relevant, or first received result code is returned -- determining the result code to be returned in this case is a local matter. A DSA which chains an operation having a control (or controls) attached must ensure that a properly formed response is returned. This requires that the DSA understand and know how to aggrigate the results of all controls which it allows to remain attached to an operation being chained. If the DSA does not understand or support a control which is marked non-critical, it removes the control prior to chaining the operation. The DSA may return unavailableCriticalExtension for critical controls that it cannot or will not chain. {TODO: give SSS as an example?} Sermersheim Expires August 26, 2005 [Page 26] Internet-Draft Distributed Procedures for LDAP Operations February 2005 4.8.1.1 Handling referrals during sub-operations If a referral is returned in response to a sub-operation, the sending DSA may attempt to further chain the operation. In the event that the DSA does not further chain the sub-operation, it will use the referral to construct an intermediate referral, and return it appropriately. When using a referral to construct an intermediate referral, certain transformations may have to happen. For example, when using a referral to construct a searchResultReference, it must be assured that the <dn> field is present, and that the <scope> field is properly updated. 4.8.2 Duplicate Elimination When search result references cause the DSA to chain a search, it is possible that duplicate objects will be returned by different remote DSAs. These duplicate objects must be sensed and not returned. {TODO: Even though there are costs associated with returning duplicates, is it a worthy exercise to build in an allowance for them to be returned? In other words, do we want to add a way for a client (or administrator) to say "it's ok, return the duplicates, let the client deal with them"? Allowing is seen as a cost benefit to the DSA.} 4.9 Returning a Referral or Intermediate Referral There are two ways in which the fields of the ContinuationReference may be conveyed in a response containing or consisting of referral or intermediate referral. A paired control is introduced for the purpose of soliciting and returning a ContinuationReference. In absence of this control, a referral or intermediate referral may be returned which conveys the information present in the ContinuationReference. A method of converting a ContinuationReference to an LDAP URL is provided for referrals and intermediate referrals which identify LDAP-enabled DSAs. Methods for converting a ContinuationReference to URIs which identify non-LDAP servers is not provided here, but may be specified in future documents, as long as they can represent the data needed to provide the same level of service. 4.9.1 ReturnContinuationReference controls This control is sent when a client wishes to receive a ContinuationReference in the event that a referral or intermediate referral is being returned. If returned, the ContinuationReference will hold all data but the referralURI field. the referralURI values will be held in the referral or intermediate referral (Referral, Sermersheim Expires August 26, 2005 [Page 27] Internet-Draft Distributed Procedures for LDAP Operations February 2005 SearchResultReference, etc.). 4.9.1.1 ReturnContinuationReference request control Solicits the return of a ReturnContinuationReference response control on messages consisting of (or carrying) a referral or intermediate referral. The controlType is IANA-ASSIGNED-OID.3, the criticality is set at the sender's discretion, the controlValue is omitted. 4.9.1.2 ReturnContinuationReference response control In response to the ReturnContinuationReference request control, this holds a ContinuationReference for messages consisting of (or carrying) a referral or intermediate referral. The controlType is IANA-ASSIGNED-OID.3, the controlValue is the BER-encoding of a ContinuationReference. Note that the referralURI field is optionally omitted when the ContinuationReference is sent in this control value. In this event, the URI(s) found in the referral or intermediate referral (Referral, SearchContinuationReference, etc.) are to be used in its stead. {TODO: is returining the referralURI outside an unneeded complication?} 4.9.2 Converting a ContinuationReference to an LDAP URL This section details the way in which an LDAP URL (from the referral or intermediate referral) is used to convey the fields of a ContinuationReference. Where existing LDAP URL fields are insufficient, extensions are introduced. Note that further extensions to the ContinuationReference type require further specifications here. {TODO: explain that each ldap url in the continuation refrerence is examined and converted} These instructions must be applied to each LDAP URL value within the referral or intermediate referral. 4.9.2.1 Conveying the target name If the <dn> part of the LDAP URL is already present, it is determined to be the candidate target object. Otherwise, the candidate target object comes from the ContinuationReference.localReference. Once the candidate target object is determined, the value of ContinuationReference.remainingName is prepended to the candidate target object. This new value becomes the target object and its string value (as specified by <distinguishedName> in [RFC2253]) is placed in the <dn> part of the LDAP URL. Sermersheim Expires August 26, 2005 [Page 28] Internet-Draft Distributed Procedures for LDAP Operations February 2005 4.9.2.2 ContinuationReference.localReference This is conveyed as an extension. The extype is IANA-ASSIGNED-OID.4 or the descriptor 'localReference', and the exvalue is the string DN encoding (as specified by <distinguishedName> in [RFC2253]) of the ContinuationReference.localReference value. 4.9.2.3 ContinuationReference.referenceType This is conveyed as an extension. The extype is IANA-ASSIGNED-OID.5 or the descriptor 'referenceType'. If the ContinuationReference.referenceType is one of superior, subordinate, cross, nonSpecificSubordinate, suplier, master, immediateSuperior, or self, the exvalue 'superior', 'subordinate', 'cross', 'nonSpecificSubordinate', 'suplier', 'master', 'immediateSuperior', or 'self' respectively. 4.9.2.4 ContinuationReference.searchScope If the search scope is one of baseObject, singleLevel, or wholeSubtree, then it may be conveyed in the 'scope' part of the LDAP URL as 'base', 'one', or 'sub' respectively. If the search scope is subordinateSubtree, then it may be conveyed in the <extension> form as documented in [LDAP-SUBORD]. If this extension is present, it MUST be marked critical. This ensures that a receiver which is unaware of this extension uses the proper search scope, or fails to progress the operation. 4.9.2.5 ContinuationReference.searchedSubtrees This field is conveyed as an extension. The extype is IANA-ASSIGNED-OID.6 or the descriptor 'searchedSubtrees', and the exvalue is the ContinuationReference.searchedSubtree value encoded according to the following searchedSubtrees ABNF: searchedSubtrees = 1*(LANGLE searchedSubtree RANGLE) searchedSubtree = <distinguishedName> from [RFC2253] LANGLE = %x3C ; left angle bracket ("<") RANGLE = %x3E ; right angle bracket (">") Each searchedSubtree represents one RDNSequence value in the ContinuationReference.searchedSubtree field. An example of a searchedSubtrees value containing two searched subtrees is: <dc=example,dc=com><cn=ralph,dc=users,dc=example,dc=com>. 4.9.2.6 ContinuationReference.failedName This field is conveyed as an extension. The extype is Sermersheim Expires August 26, 2005 [Page 29] Internet-Draft Distributed Procedures for LDAP Operations February 2005 IANA-ASSIGNED-OID.7 or the descriptor 'failedName', and the exvalue is the string DN encoding (as specified in [RFC2253]) of the ContinuationReference.failedName value. 4.10 Acting on a Referral or Intermediate Referral When a protocol peer receives a referral or intermediate referral, it may distribute the operation either by sending a ChainedRequest, or by emulating the ChainedRequest. Prior to taking these steps, the protocol peer effectively converts the referral or intermediate referral into a ContinuationReference. Then, acting in the same manner as a DSA would, follows the directions in Section 4.4 if sending a ChainedRequest, or Section 4.5 otherwise. 4.10.1 Converting a Referral or Intermediate Referral to a ContinuationReference A referral or intermediate referral may be converted (or conceptually converted) to a ContinuationReference type in order to follow the distributed operation procedures in Section 4.4, or Section 4.5. The following steps may only be used to convert a referral or intermediate referral containing LDAP URL values. Converting other types of URIs may be specified in future documents as long as the conversion provides the same level of service found here. o The ContinuationReference.referralURI is populated with all LDAP URL values in the referral or intermediate referral. o The ContinuationReference.localReference populate with the value of the localReference extension value (Section 4.9.2.2) if one exists. Otherwise it is omitted. o The ContinuationReference.referenceType populate with the value of the referenceType extension value (Section 4.9.2.3) if one exists. Otherwise it is omitted. o The ContinuationReference.remainingName is omitted. o The ContinuationReference.searchScope is populated with subordinateSubtree if the subordScope LDAP URL extension [LDAP-SUBORD] is present. If the <scope> field contains te value 'base', 'one', 'sub', or 'subordinates', this filed is populated with baseObject, singleLevel, wholeSubtree, or subordinateSubtree respectively. Otherwise this field is omitted. o The ContinuationReference.searchedSubtrees is populated with any searchedSubtrees LDAP URI extension Section 4.9.2.5 value found on an LDAP URI in the referral or intermediate referral. If none exist, this field is omitted. o The ContinuationReference.failedName is populated with any failedName LDAP URI extension Section 4.9.2.6 value found on an LDAP URI in the referral or intermediate referral. If none exist, this field is omitted. Sermersheim Expires August 26, 2005 [Page 30] Internet-Draft Distributed Procedures for LDAP Operations February 2005 Note that many fields are simply omitted. This is either because they are conveyed within the LDAP URL values themselves, and subsequent instructions will check for their presence, or because they are not needed (they are redundant or not used in further instructions). 4.11 Ensuring non-existence of an entry under an nssr {TODO: add a huge disclaimer here that says without transactional semantics, you can never be sure that the entry didn't get added. Maybe we should just punt on this and say it's a local matter} In order to ensure there are no entries matching the name of the entry to be added or renamed immediately subordinate to an nssr, these steps may be followed. If the DSA is able and allowed to chain operations, it may contact each of the DSAs listed as access points in the nssr (in the ref attribute) and using a base-level search operation it will determine whether or not the object to be added exists. Note that access control or other policies may hide the entry from the sending DSA. If the entry does not exist on any of the DSAs listed in the nssr, the operation may progress on the local DSA. If the DSA cannot make this determination, the operation fails with affectsMultipleDSAs. 4.12 Mapping a referralURI to an LDAP URI As with any URI specification which is intended to be used as a URI which conveys referral information, the LDAP URI specification is given a mapping to the elements of a referralURI as specified in. Section 3.1.1.1. These mappings are given here using the ABNF identifiers given in [RFC2255]. referralURI to LDAP URI mapping: +---------------------------------+---------------------------------+ | referralURI element | LDAP URL element | +---------------------------------+---------------------------------+ | protocolIdentifier | <scheme> | | | | | accessPoint | <hostport> | | | | | targetObject | <dn>. This must be encoded as a | | | <distinguishedName> as | | | specified in [RFC2253] | | | | | localReference | LDAP URL localReference | Sermersheim Expires August 26, 2005 [Page 31] Internet-Draft Distributed Procedures for LDAP Operations February 2005 | | extension as specified in | | | Section 4.9.2.2 | | | | | referenceType | LDAP URL referenceType | | | extension as specified in | | | Section 4.9.2.3 | | | | | searchScope | <scope> or LDAP URL subordScope | | | extension as specified in | | | Section 4.9.2.4 | | | | | searchedSubtrees | LDAP URL searchedSubtrees | | | extension as specified in | | | Section 4.9.2.5 | | | | | failedName | LDAP URL failedName extension | | | as specified in Section 4.9.2.6 | +---------------------------------+---------------------------------+ 4.13 Using the ManageDsaIT control This control, defined in [RFC3296], allows the management of the distributed knowledge information held by a DSA, and thus overrides the determinations made during name resolution and operation evaluation. When this control is attached to an operation, all resolved and acted upon DSEs are treated as being local to the DSA. This is true regardless of the phase the operation is in. Thus referrals are never returned and chaining never occurs. Sermersheim Expires August 26, 2005 [Page 32] Internet-Draft Distributed Procedures for LDAP Operations February 2005 5. Security Considerations This document introduces a mechanism (chaining) which can be used to propagate directory operation requests to servers which may be inaccessible otherwise. Implementers and deployers of this technology should be aware of this and take appropriate steps such that firewall mechanisms are not compromised. This document introduces the ability to return auxiliary data when returning referrals. Measures should be taken to ensure proper protection of his data. Implementers must ensure that any specified time, size, and administrative limits are not circumvented due to the mechanisms introduced here. 6. Normative References [LDAP-SUBORD] Sermersheim, J., "Subordinate Subtree Search Scope for LDAP", Internet-Draft draft-sermersheim-ldap-subordinate-scope, July 2004. [RFC2079] Smith, M., "Definition of an X.500 Attribute Type and an Object Class to Hold Uniform Resource Identifiers (URIs)", RFC 2079, January 1997. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2251] Wahl, M., Howes, T. and S. Kille, "Lightweight Directory Access Protocol (v3)", RFC 2251, December 1997. [RFC2253] Wahl, M., Kille, S. and T. Howes, "Lightweight Directory Access Protocol (v3): UTF-8 String Representation of Distinguished Names", RFC 2253, December 1997. [RFC2255] Howes, T. and M. Smith, "The LDAP URL Format", RFC 2255, December 1997. [RFC2396] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform Resource Identifiers (URI): Generic Syntax", RFC 2396, August 1998. [RFC3296] Zeilenga, K., "Named Subordinate References in Lightweight Directory Access Protocol (LDAP) Directories", RFC 3296, July 2002. Sermersheim Expires August 26, 2005 [Page 33] Internet-Draft Distributed Procedures for LDAP Operations February 2005 [RFC3377] Hodges, J. and R. Morgan, "Lightweight Directory Access Protocol (v3): Technical Specification", RFC 3377, September 2002. [RFC3383] Zeilenga, K., "Internet Assigned Numbers Authority (IANA) Considerations for the Lightweight Directory Access Protocol (LDAP)", BCP 64, RFC 3383, September 2002. [RFC3771] Harrison, R. and K. Zeilenga, "The Lightweight Directory Access Protocol (LDAP) Intermediate Response Message", RFC 3771, April 2004. [X500] International Telephone and Telegraph Consultative Committee, "The Directory - overview of concepts, models and services", ITU-T Recommendation X.500, November 1993. [X518] International Telephone and Telegraph Consultative Committee, "The Directory - The Directory: Procedures for distributed operation", ITU-T Recommendation X.518, November 1993. [X680] International Telecommunications Union, "Abstract Syntax Notation One (ASN.1): Specification of basic notation", ITU-T Recommendation X.680, July 2002. [X690] International Telecommunications Union, "Information Technology - ASN.1 encoding rules: Specification of Basic Encoding Rules (BER), Canonical Encoding Rules (CER) and Distinguished Encoding Rules (DER)", ITU-T Recommendation X.690, July 2002. Author's Address Jim Sermersheim Novell, Inc 1800 South Novell Place Provo, Utah 84606 USA Phone: +1 801 861-3088 Email: jimse@novell.com Sermersheim Expires August 26, 2005 [Page 34] Internet-Draft Distributed Procedures for LDAP Operations February 2005 Appendix A. IANA Considerations Registration of the following values is requested [RFC3383]. A.1 LDAP Object Identifier Registrations It is requested that IANA register upon Standards Action an LDAP Object Identifier in identifying the protocol elements defined in this technical specification. The following registration template is provided: Subject: Request for LDAP OID Registration Person & email address to contact for further information: Jim Sermersheim jimse@novell.com Specification: RFCXXXX Author/Change Controller: IESG Comments: Seven delegations will be made under the assigned OID: IANA-ASSIGNED-OID.1 ChainedRequest LDAP Extended Operation IANA-ASSIGNED-OID.2 Supported Feature: Can Chain Operations IANA-ASSIGNED-OID.3 ReturnContinuationReference LDAP Controls IANA-ASSIGNED-OID.4 localReference: LDAP URL Extension IANA-ASSIGNED-OID.6 searchedSubtree: LDAP URL Extension IANA-ASSIGNED-OID.7 failedName: LDAP URL Extension A.2 LDAP Protocol Mechanism Registrations It is requested that IANA register upon Standards Action the LDAP protocol mechanism described in this document. The following registration templates are given: Subject: Request for LDAP Protocol Mechanism Registration Object Identifier: IANA-ASSIGNED-OID.1 Description: ChainedRequest LDAP Extended Operation Person & email address to contact for further information: Jim Sermersheim jimse@novell.com Usage: Extension Specification: RFCXXXX Author/Change Controller: IESG Comments: none Subject: Request for LDAP Protocol Mechanism Registration Object Identifier: IANA-ASSIGNED-OID.2 Description: Can Chain Operations Supported Feature Person & email address to contact for further information: Sermersheim Expires August 26, 2005 [Page 35] Internet-Draft Distributed Procedures for LDAP Operations February 2005 Jim Sermersheim jimse@novell.com Usage: Feature Specification: RFCXXXX Author/Change Controller: IESG Comments: none Subject: Request for LDAP Protocol Mechanism Registration Object Identifier: IANA-ASSIGNED-OID.3 Description: ReturnContinuationReference LDAP Controls Person & email address to contact for further information: Jim Sermersheim jimse@novell.com Usage: Control Specification: RFCXXXX Author/Change Controller: IESG Comments: none Subject: Request for LDAP Protocol Mechanism Registration Object Identifier: IANA-ASSIGNED-OID.4 Description: localReference LDAP URL Extension Person & email address to contact for further information: Jim Sermersheim jimse@novell.com Usage: Extension Specification: RFCXXXX Author/Change Controller: IESG Comments: none Subject: Request for LDAP Protocol Mechanism Registration Object Identifier: IANA-ASSIGNED-OID.5 Description: referenceType LDAP URL Extension Person & email address to contact for further information: Jim Sermersheim jimse@novell.com Usage: Extension Specification: RFCXXXX Author/Change Controller: IESG Comments: none Subject: Request for LDAP Protocol Mechanism Registration Object Identifier: IANA-ASSIGNED-OID.6 Description: searchedSubtree LDAP URL Extension Person & email address to contact for further information: Jim Sermersheim jimse@novell.com Usage: Extension Sermersheim Expires August 26, 2005 [Page 36] Internet-Draft Distributed Procedures for LDAP Operations February 2005 Specification: RFCXXXX Author/Change Controller: IESG Comments: none Subject: Request for LDAP Protocol Mechanism Registration Object Identifier: IANA-ASSIGNED-OID.7 Description: failedName LDAP URL Extension Person & email address to contact for further information: Jim Sermersheim jimse@novell.com Usage: Extension Specification: RFCXXXX Author/Change Controller: IESG Comments: none A.3 LDAP Descriptor Registrations It is requested that IANA register upon Standards Action the LDAP descriptors described in this document. The following registration templates are given: Subject: Request for LDAP Descriptor Registration Descriptor (short name): localReference Object Identifier: IANA-ASSIGNED-OID.4 Person & email address to contact for further information: Jim Sermersheim jimse@novell.com Usage: URL Extension Specification: RFCXXXX Author/Change Controller: IESG Comments: none Subject: Request for LDAP Descriptor Registration Descriptor (short name): referenceType Object Identifier: IANA-ASSIGNED-OID.5 Person & email address to contact for further information: Jim Sermersheim jimse@novell.com Usage: URL Extension Specification: RFCXXXX Author/Change Controller: IESG Comments: none Subject: Request for LDAP Descriptor Registration Descriptor (short name): searchedSubtree Object Identifier: IANA-ASSIGNED-OID.6 Person & email address to contact for further information: Sermersheim Expires August 26, 2005 [Page 37] Internet-Draft Distributed Procedures for LDAP Operations February 2005 Jim Sermersheim jimse@novell.com Usage: URL Extension Specification: RFCXXXX Author/Change Controller: IESG Comments: none Subject: Request for LDAP Descriptor Registration Descriptor (short name): failedName Object Identifier: IANA-ASSIGNED-OID.7 Person & email address to contact for further information: Jim Sermersheim jimse@novell.com Usage: URL Extension Specification: RFCXXXX Author/Change Controller: IESG Comments: none A.4 LDAP Result Code Registrations It is requested that IANA register upon Standards Action the LDAP result codes described in this document. The following registration templates are given: Subject: Request for LDAP Result Code Registration Result Code Name: invalidReference Person & email address to contact for further information: Jim Sermersheim jimse@novell.com Usage: URL Extension Specification: RFCXXXX Author/Change Controller: IESG Comments: none Sermersheim Expires August 26, 2005 [Page 38] Internet-Draft Distributed Procedures for LDAP Operations February 2005 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights 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; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM 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. Copyright Statement Copyright (C) The Internet Society (2005). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Sermersheim Expires August 26, 2005 [Page 39]PK G]�Z�(� (� C doc/alt-openldap11-devel/drafts/draft-haripriya-dynamicgroup-xx.txtnu �[��� Network Working Group S. Haripriya Internet-Draft Jaimon. Jose, Ed. Updates: 02 (if approved) Jim. Sermersheim Intended status: Standards Track Novell, Inc. Expires: July 9, 2007 January 5, 2007 LDAP: Dynamic Groups for LDAPv3 draft-haripriya-dynamicgroup-02 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on July 9, 2007. Copyright Notice Copyright (C) The Internet Society (2007). Haripriya, et al. Expires July 9, 2007 [Page 1] Internet-Draft LDAP: Dynamic Groups for LDAPv3 January 2007 Abstract This document describes the requirements, semantics, schema elements, and operations needed for a dynamic group feature in LDAP. A dynamic group is defined here as a group object with a membership list of distinguished names that is dynamically generated using LDAP search criteria. The dynamic membership list may then be interrogated by LDAP search and compare operations, and may also be used to find the groups that an object is a member of. This feature eliminates a huge amount of the administrative effort required today for maintaining group memberships and role-based operations in large enterprises. Table of Contents 1. Conventions used in this document . . . . . . . . . . . . . . 4 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. Requirements of a dynamic group feature . . . . . . . . . . . 6 4. Schema and Semantic Definitions for Dynamic Groups . . . . . . 7 4.1. Object Classes . . . . . . . . . . . . . . . . . . . . . . 7 4.1.1. dynamicGroup . . . . . . . . . . . . . . . . . . . . . 7 4.1.2. dynamicGroupOfUniqueNames . . . . . . . . . . . . . . 7 4.1.3. dynamicGroupAux . . . . . . . . . . . . . . . . . . . 7 4.1.4. dynamicGroupOfUniqueNamesAux . . . . . . . . . . . . . 7 4.2. Attributes . . . . . . . . . . . . . . . . . . . . . . . . 8 4.2.1. memberQueryURL . . . . . . . . . . . . . . . . . . . . 8 4.2.2. excludedMember . . . . . . . . . . . . . . . . . . . . 11 4.3. member . . . . . . . . . . . . . . . . . . . . . . . . . . 11 4.4. uniqueMember . . . . . . . . . . . . . . . . . . . . . . . 11 4.5. dgIdentity . . . . . . . . . . . . . . . . . . . . . . . . 11 4.5.1. dgIdentity - Security implications . . . . . . . . . . 12 5. Advertisement of support for dynamic groups . . . . . . . . . 13 6. Dynamic Group Operations . . . . . . . . . . . . . . . . . . . 14 6.1. Existing Operations . . . . . . . . . . . . . . . . . . . 14 6.1.1. Access to resources in the directory . . . . . . . . . 14 6.1.2. Reading a dynamic group object . . . . . . . . . . . . 14 6.1.3. 'Is Member Of' functionality . . . . . . . . . . . . . 15 6.2. New Extensions . . . . . . . . . . . . . . . . . . . . . . 16 6.2.1. Managing the static members of a dynamic group . . . . 16 7. Performance Considerations . . . . . . . . . . . . . . . . . . 17 7.1. Caching of Dynamic Members . . . . . . . . . . . . . . . . 17 8. Security Considerations . . . . . . . . . . . . . . . . . . . 18 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19 10. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . 20 11. Normative References . . . . . . . . . . . . . . . . . . . . . 21 Appendix A. Example Values for memberQueryURL . . . . . . . . . . 22 Appendix B. Acknowledgments . . . . . . . . . . . . . . . . . . . 23 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 24 Haripriya, et al. Expires July 9, 2007 [Page 2] Internet-Draft LDAP: Dynamic Groups for LDAPv3 January 2007 Intellectual Property and Copyright Statements . . . . . . . . . . 25 Haripriya, et al. Expires July 9, 2007 [Page 3] Internet-Draft LDAP: Dynamic Groups for LDAPv3 January 2007 1. Conventions used in this document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [1]. Haripriya, et al. Expires July 9, 2007 [Page 4] Internet-Draft LDAP: Dynamic Groups for LDAPv3 January 2007 2. Introduction The LDAP schema described in [4] defines two object classes: 'groupOfNames', and 'groupOfUniqueNames', that hold a static list of distinguished names in their 'member' or 'uniqueMember' attributes respectively, and are typically used to describe a group of objects for various functions. These grouping functions range from simple group membership applications such as email distribution lists to describing common authorization for a set of users The administration and updating of these membership lists must be done by specifically modifying the DN values in the member or uniqueMember attributes. Thus, each time a change in membership happens, a process must exist which adds or removes the particular entry's DN from the member attribute. For example, consider an organization, where the access to its facilities is controlled by membership in a directory group. Assume that all employees in a department have been added to the group that provides access to the required department facility. If an employee moves from one department to another, the administrator must remove the employee from one group and add him to another. Similarly consider an organization that wants to provide access to its facility, to both interns and employees on weekdays, but only to employees on weekends. It would be effort-consuming to achieve this with static groups. "Dynamic groups" are like normal groups, but they let one specify criteria to be used for evaluating membership to a group; the membership of the group is determined dynamically by the directory servers involved. This lets the group administrator define the membership in terms of attributes, and let the DSAs worry about who are the actual members. This solution is more scalable and reduces administrative costs. This can also supplement static groups in LDAP to provide flexibility to the user. Haripriya, et al. Expires July 9, 2007 [Page 5] Internet-Draft LDAP: Dynamic Groups for LDAPv3 January 2007 3. Requirements of a dynamic group feature The following requirements SHOULD be met by a proposal for the dynamic groups feature: 1. Creation and administration of dynamic groups should be done using normal LDAP operations. 2. Applications must be able to use dynamic groups in the same way that they are able to use static groups for listing members and for membership evaluation. 3. Interrogation of a dynamic group's membership should be done using normal LDAP operations, and should be consistent. This means that all authorization identities with the same permission to the membership attribute of a dynamic group (such as 'read') should be presented with the same membership list. Haripriya, et al. Expires July 9, 2007 [Page 6] Internet-Draft LDAP: Dynamic Groups for LDAPv3 January 2007 4. Schema and Semantic Definitions for Dynamic Groups The dynamic group classes are defined by the following schema 4.1. Object Classes The following object classes MUST be supported, and their semantics understood by the server, for it to support the dynamic groups feature. 4.1.1. dynamicGroup ( <OID.TBD> NAME 'dynamicGroup' SUP groupOfNames STRUCTURAL MAY (memberQueryURL $ excludedMember $ dgIdentity )) This structural object class is used to create a dynamic group object. It is derived from groupOfNames, which is defined in [4]. 4.1.2. dynamicGroupOfUniqueNames ( <OID.TBD> NAME 'dynamicGroupOfUniqueNames' SUP groupOfUniqueNames STRUCTURAL MAY (memberQueryURL $ excludedMember $ dgIdentity )) This structural object class is used to create a dynamic group object whose membership list is held in a uniqueMember attribute. It is derived from groupOfUniqueNames, which is defined in [4]. 4.1.3. dynamicGroupAux ( <OID.TBD> NAME 'dynamicGroupAux' SUP groupOfNames AUXILIARY MAY (memberQueryURL $ excludedMember $ dgIdentity )) This auxiliary object class is used to convert an existing object to a dynamic group or to create an object of another object class but with dynamic group capabilities. This is derived from groupOfNames which is defined in [4]. 4.1.4. dynamicGroupOfUniqueNamesAux ( <OID.TBD> NAME 'dynamicGroupOfUniqueNamesAux' SUP groupOfUniqueNames AUXILIARY MAY (memberQueryURL $ excludedMember $ dgIdentity )) This auxiliary object class is used to convert an existing object to a dynamic group of unique names or to create an object of another object class but with dynamic group capabilities. This is derived from groupOfUniqueNames which is defined in [4]. Haripriya, et al. Expires July 9, 2007 [Page 7] Internet-Draft LDAP: Dynamic Groups for LDAPv3 January 2007 4.2. Attributes The following attribute names MUST be supported by the server. 4.2.1. memberQueryURL This attribute describes the membership of the list using an LDAPURL [3]. (<OID.TBD> NAME 'memberQueryURL' SYNTAX 1.3.6.1.4.1.1466.115.121.1.26 ) The value of memberQueryURL is encoded as an LDAPURL [3] Haripriya, et al. Expires July 9, 2007 [Page 8] Internet-Draft LDAP: Dynamic Groups for LDAPv3 January 2007 The BNF from [3] is listed here for reference. ldapurl = scheme COLON SLASH SLASH [host [COLON port]] [SLASH dn [QUESTION [attributes] [QUESTION [scope] [QUESTION [filter] [QUESTION extensions]]]]] ; <host> and <port> are defined ; in Sections 3.2.2 and 3.2.3 ; of [RFC3986]. ; <filter> is from Section 3 of ; [RFC4515], subject to the ; provisions of the ; "Percent-Encoding" section ; below. scheme = "ldap" dn = distinguishedName ; From Section 3 of [RFC4514], ; subject to the provisions of ; the "Percent-Encoding" ; section below. attributes = attrdesc *(COMMA attrdesc) attrdesc = selector *(COMMA selector) selector = attributeSelector ; From Section 4.5.1 of ; [RFC4511], subject to the ; provisions of the ; "Percent-Encoding" section ; below. scope = "base" / "one" / "sub" extensions = extension *(COMMA extension) extension = [EXCLAMATION] extype [EQUALS exvalue] extype = oid ; From section 1.4 of [RFC4512]. exvalue = LDAPString ; From section 4.1.2 of ; [RFC4511], subject to the ; provisions of the ; "Percent-Encoding" section ; below. EXCLAMATION = %x21 ; exclamation mark ("!") SLASH = %x2F ; forward slash ("/") COLON = %x3A ; colon (":") QUESTION = %x3F ; question mark ("?") For the purpose of evaluating dynamic members, the directory server uses only the dn, scope, filter and extensions fields. All remaining fields are ignored if specified. If other fields are specified, the server SHALL ignore them and MAY omit them when presenting the value to a client. The dn is used to specify the base dn from which to start the search for dynamic members. The scope specifies the scope with respect to the dn in which to search for dynamic members. The filter specifies the criteria with which to select objects for dynamic membership. Haripriya, et al. Expires July 9, 2007 [Page 9] Internet-Draft LDAP: Dynamic Groups for LDAPv3 January 2007 4.2.1.1. The x-chain extension A new extension is defined for use of the memberQueryURL in dynamic groups, named 'x-chain'. x-chain does not take a value. When x-chain is present, the server must follow any search continuation references to other servers while searching for dynamic members. When x-chain is absent, the dynamic members computed will be only those that are present on the server from which the search is made. A directory server supporting the memberQueryURL MAY support the x-chain extension, thus the x-chain extension could be critical or non- critical as specified by the '!' prefix to the extension type. 4.2.1.2. Semantics of multiple values for memberQueryURL The memberQueryURL MAY have multiple values, and in that case, the members of the dynamic group will be the union of the members computed using each individual URL value. This is useful in specifying a group membership that is made up from subtrees rooted at different base DNs, and possibly using different filters. 4.2.1.3. Condition of membership An object O is a member of a dynamic group G if and only if (( O is a value of the 'member' or 'uniqueMember' attribute of G) OR (( O is selected by the membership criteria specified in the 'memberQueryURL' attribute values of G) AND ( O is not listed in the 'excludedMember' attribute of G) )) If a member M of a dynamic group G happens to be a dynamic or a static group, the static or dynamic members of M SHALL NOT be considered as members of G. M is a member of G though. The last condition is imposed because o Recursively evaluating members of members may degrade the performance of the server drastically. o Looping may occur particularly in situations where the search chains across multiple-servers. Haripriya, et al. Expires July 9, 2007 [Page 10] Internet-Draft LDAP: Dynamic Groups for LDAPv3 January 2007 o Dynamic membership assertions (compare operation) cannot be optimized if recursive memberships are allowed. Without recursion, comparisons can be made light-weight. 4.2.2. excludedMember ( <OID.TBD> NAME 'excludedMember' SUP distinguishedName ) This attribute is used to exclude entries from being a dynamic member of a dynamic group. Thus an entry is a dynamic member of a dynamic group if and only if it is selected by the member criteria specified by the 'memberQueryURL' attribute or explicitly added to the member or uniqueMember attribute, and it is not listed in the 'excludedMember' attribute. 4.3. member ( 2.5.4.31 NAME 'member' SUP distinguishedName ) Defined in [4], this attribute is overloaded when used in the context of a dynamic group. It is used to explicitly specify static members of a dynamic group. If the same entry is listed in both the 'member' and 'excludedMember' attributes, the 'member' overrides the 'excludedMember', and the entry is considered to be a member of the group. This attribute is also used to interrogate both the static and dynamic member values of a dynamic group object. Subclasses of this attribute are NOT considered in this manner. 4.4. uniqueMember ( 2.5.4.32 NAME 'uniqueMember' SUP distinguishedName ) Defined in [4], this attribute is overloaded when used in the context of a dynamic group. It is used to specify the static members of a dynamic group. If the same entry is listed in both the 'uniqueMember' and 'excludedMember' attributes, the 'uniqueMember' overrides the 'excludedMember', and the entry is considered to be a member of the group. This attribute is also used to interrogate both the static and dynamic member values of a dynamic group object. Subclasses of this attribute are NOT considered in this manner. 4.5. dgIdentity ( <OID.TBD> NAME 'identity' SUP distinguishedName SINGLE-VALUE ) In order to provide consistent results when processing the search criteria, the server must use a single authorization identity. If the authorization of the bound identity is used, the membership list Haripriya, et al. Expires July 9, 2007 [Page 11] Internet-Draft LDAP: Dynamic Groups for LDAPv3 January 2007 will vary, from identity to identity due to differing access controls. This may either be done by the server authenticating as the dgIdentity prior to performing a search or compare operation, or may be done by simply assuming the authorization of the dgIdentity when performing those operations. As server implementations vary, so may the mechanisms to achieve consistent results through the use of the dgIdentity. In the case that the server authenticates as the dgIdentity, it may be required by the server that this identity have proper authentication credentials, and it may be required that this identity reside in the DIB of the local server. In the absence of an identity value, or in case the identity value cannot be used, the server will process the memberQueryURL as the anonymous identity. This attribute MAY be supported, and represents the identity the server will use for processing the memberQueryURL. 4.5.1. dgIdentity - Security implications Because this attribute indirectly but effectively grants anyone with read or compare access to the member or uniqueMember attribute sufficient permission to gain a DN result set from the memberQueryURL, server implementations SHOULD NOT allow this attribute to be populated with the DN of any object that is not administered by the identity making the change to this attribute. For purposes of this document, to "administer an object" indicates that the administrative identity has the ability to fully update the access control mechanism in place the object in question. As of this writing, there is no way to describe further what it means to be fully able to administer the access control mechanism for an object, so this definition is left as implementation-specific. This requirement will allow an entity that has privileges to administer a particular subtree (meaning that entity can add, delete, and update objects in that subtree), to place in the dgIdentity DNs of only those objects it administers. Haripriya, et al. Expires July 9, 2007 [Page 12] Internet-Draft LDAP: Dynamic Groups for LDAPv3 January 2007 5. Advertisement of support for dynamic groups If the dynamic groups schema is not present on an LDAP server, it MUST be assumed that the dynamic groups feature is not supported. Haripriya, et al. Expires July 9, 2007 [Page 13] Internet-Draft LDAP: Dynamic Groups for LDAPv3 January 2007 6. Dynamic Group Operations 6.1. Existing Operations The following operations SHOULD expose the dynamic groups functionality. These operations do not require any change in the LDAP protocol to be exchanged between the client and server. 6.1.1. Access to resources in the directory If access control items are set on a target resource object in the directory, with the subject being a dynamic group object, then all the members of the group object, including the dynamic members, will get the same permissions on the target entry. This would be the most useful application of dynamic groups as seen by an administrator because it lets the server control access to resources based on dynamic membership to a trustee (subject of ACI) of the resource. The way to specify a dynamic ACL is currently implementation specific, as there is no common ACL definition for LDAP, and hence will be dealt with in a separate document or later (TO BE DONE). 6.1.2. Reading a dynamic group object When the member attributes of a dynamic group object is listed by the client using an LDAP search operation, the member values returned SHOULD contain both the static and dynamic members of the group object. This functionality will not require a change to the protocol, and the clients need not be aware of dynamic groups to exploit this functionality. This feature is useful for clients that determine access privileges to a resource by themselves, by reading the members of a group object. It will also be useful to administrators who want to see the result of the query URL that they set on the dynamic group entry. Note that this overloads the semantics of the 'member' and 'uniqueMember' attributes. This could lead to some surprises for the client . for example: Clients that read the member attribute of a dynamic group object and then attempt to remove values (which were dynamic) could get an error specifying such a value was not there. Example: Let cn=dg1,o=myorg be a dynamic group object with the following attributes stored in the directory. Haripriya, et al. Expires July 9, 2007 [Page 14] Internet-Draft LDAP: Dynamic Groups for LDAPv3 January 2007 member: cn=admin,o=myorg excludedMember: cn=guest,ou=finance,o=myorg excludedMember: cn=robin,ou=finance,o=myorg memberQueryURL: ldap:///ou=finance,o=myorg??sub?(objectclass=organizationalPerson) If there are 5 organizationalPerson objects under ou=finance,o=myorg with common names bob, alice, john, robin, and guest, then the output of a base-scope LDAP search at cn=dg1,o=myorg, with the attribute list containing 'member' will be as follows: dn: cn=dg1,o=myorg member: cn=admin,o=myorg member: cn=bob,ou=finance,o=myorg member: cn=alice,ou=finance,o=myorg member: cn=john,ou=finance,o=myorg 6.1.3. 'Is Member Of' functionality The LDAP compare operation allows one to discover whether a given DN is in the membership list of a dynamic group. Again, the server SHOULD produce consistent results among different authorization identities when processing this request, as long as those identities have the same access to the member or uniqueMember attribute. Using the data from the example in Section 6.1.2, a compare on cn=dg1,o=myorg, for the AVA member=cn=bob,ou=finance,o=myorg would result in a response of compareTrue (assuming the bound identity was authorized to compare the member attribute of cn=dg1,o=myorg). Likewise, a search operation that contains an equalityMatch or presence filter, naming the member or uniqueMember attribute as the attribute (such as (member= cn=bob,ou=finance,o=myorg), or (member=*)), will cause the server to evaluate this filter against the rules given in Section 4.2.1.3 in the event that the search is performed on a dynamic group object. As of this writing, no other matching rules exist for the distinguished name syntax, thus no requirements beyond equalityMatch are given here. Haripriya, et al. Expires July 9, 2007 [Page 15] Internet-Draft LDAP: Dynamic Groups for LDAPv3 January 2007 6.2. New Extensions The following new extensions are added for dynamic group support. 6.2.1. Managing the static members of a dynamic group Because a dynamic group overloads the semantics of the member and uniqueMember attributes, a mechanism is needed to retrieve the static values found in these attributes for management purposes. To serve this need, a new attribute option is defined here called 'x-static'. Attribute options are discussed in Section 2.5 of [2]. This option SHALL only be specified with the 'member' or 'uniqueMember' attribute. When the LDAP server does not understand the semantics of this option on a given attribute, the option SHOULD be ignored. This attribute option is only used to affect the transmitted values, and does not impose sub-typing semantics on the attribute. This option MAY be specified by a client during a search request in the list of attributes to be returned, i.e. member;x-static. In this case, the server SHALL only return those members of the dynamic group that are statically listed as values of the member or uniqueMember attribute. The evaluation process listed in Section 9 SHALL NOT be used to populate the values to be returned. This option MAY be specified is either an equalityMatch or presence search filter. In this case, the server evaluates only the values statically listed in the member or uniqueMember attribute, and does not apply the evaluation process listed in Section 9. This option MAY be specified in update operations such as add and modify, but SHOULD be ignored, as its presence is semantically the same as its non-presence. Note to user: Performing a search to read a dynamic group, with a filter item such as (member=*), and specifying member;x-static, may result in a search result entry that has no member attribute. This may seem counter-intuitive. Haripriya, et al. Expires July 9, 2007 [Page 16] Internet-Draft LDAP: Dynamic Groups for LDAPv3 January 2007 7. Performance Considerations When the x-chain extension is present on the memberQueryURL, the server MUST follow any search continuation references to other servers while searching for dynamic members. This may be expensive and slow in a true distributed environment. The dynamicGroup implementation can consider a distributed caching feature to improve the performance. An outline of such a distributed caching is given below. 7.1. Caching of Dynamic Members Since the dynamic members of a group are computed every time the group is accessed, the performance could be affected. An implementation of dynamic groups can get around this problem by caching the computed members of a dynamic group locally and using the cached data subsequently. One way to do this is to create pseudo- objects for each dynamic group on every server that holds an object that is a dynamic member of the group. With this, the computation of the dynamic members of a group reduces to the task of reading the pseudo-objects from each server. These pseudo-objects need to be linked from the original dynamic group to speed up the member computation. Also, since these are cached objects, appropriate timeouts need to be associated with the cache after which the cache should be invalidated or refreshed Haripriya, et al. Expires July 9, 2007 [Page 17] Internet-Draft LDAP: Dynamic Groups for LDAPv3 January 2007 8. Security Considerations This document discusses the use of one object as the identity (Section 4.5) with which to read information for another object. If the creation of the dgIdentity attribute is uncontrolled, an intruder could potentially create a dynamic group with the identity of, say, the administrator, to be able to read the directory as the administrator, and see information which would be otherwise unavailable to him. Thus, a person adding an object as identity of a dynamic group should have appropriate permissions on the object being added as identity. This document also discusses using dynamic memberships to provide access for resources in a directory. As the dynamic members are not created by the administrator, there could be surprises for the administrator in the form of certain objects getting access to certain resources through dynamic membership, which the administrator never intended. So the administrator should be wary of such problems. The administrator could view the memberships and make sure that anybody who is not supposed to be a member of a group is added to the excludedMember list. Denial of service attacks can be launched on an LDAP server, by repeatedly searching for a dynamic group with a large membership list and listing the member attribute. A more effective form of denial of service attack could be launched by making searches of the form (member="somedn") at the top of tree and closing the client connection as soon as the search starts. Some administrative limits be imposed to avoid such situations. The dynamic groups feature could be potentially misused by a user to circumvent any administrative size-limit restriction placed on the server. In order to search an LDAP server and obtain the names of all the objects on the server irrespective of admin size-limit restriction on the server, the LDAP user could create a dynamic group with a memberQueryURL which matches all objects in the tree, and list just that one object. Haripriya, et al. Expires July 9, 2007 [Page 18] Internet-Draft LDAP: Dynamic Groups for LDAPv3 January 2007 9. IANA Considerations There are no IANA considerations. Haripriya, et al. Expires July 9, 2007 [Page 19] Internet-Draft LDAP: Dynamic Groups for LDAPv3 January 2007 10. Conclusions This document discusses the syntax, semantics and usage of dynamic groups in LDAPv3. Haripriya, et al. Expires July 9, 2007 [Page 20] Internet-Draft LDAP: Dynamic Groups for LDAPv3 January 2007 11. Normative References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [2] Zeilenga, K., "Lightweight Directory Access Protocol (LDAP): Directory Information Models", RFC 4512, June 2006. [3] Smith, M. and T. Howes, "Lightweight Directory Access Protocol (LDAP): Uniform Resource Locator", RFC 4516, June 2006. [4] Sciberras, A., "Lightweight Directory Access Protocol (LDAP): Schema for User Applications", RFC 4519, June 2006. Haripriya, et al. Expires July 9, 2007 [Page 21] Internet-Draft LDAP: Dynamic Groups for LDAPv3 January 2007 Appendix A. Example Values for memberQueryURL 1. This memberQueryURL value specifies the membership criteria for a dynamic group entry as "all inetorgperson entries that also have their title attribute set to 'manager', and are in the DIT-wide subtree under ou=hr,o=myorg ". memberQueryURL: ldap:/// ou=hr,o=myorg??sub?(& (objectclass=inetorgperson)(title=manager))? x-chain 2. This value lets the user specify the membership criteria for a dynamic group entry as "all entries on the local server, that either have unix accounts or belong to the unix department, and are under the engineering container ". memberQueryURL: ldap:///ou=eng,o=myorg??sub? (|(objectclass=posixaccount)(department=unix)) 3. These values let the user specify the membership criteria as "all inetorgperson entries on the local server, in either the ou=eng,o=myorg or ou=support,o=myorg" subtrees. memberQueryURL: ldap:///ou=eng,o=myorg??sub?(objectclass=inetorgperson) memberQueryURL: ldap:///ou=support,o=myorg??sub?(objectclass=inetorgperson) Haripriya, et al. Expires July 9, 2007 [Page 22] Internet-Draft LDAP: Dynamic Groups for LDAPv3 January 2007 Appendix B. Acknowledgments Funding for the RFC Editor function is currently provided by the Internet Society. Haripriya, et al. Expires July 9, 2007 [Page 23] Internet-Draft LDAP: Dynamic Groups for LDAPv3 January 2007 Authors' Addresses Haripriya S Novell, Inc. 49/1 & 49/3 Garvebhavi Palya, 7th Mile, Hosur Road Bangalore, Karnataka 560068 India Email: sharipriya@novell.com Jaimon Jose (editor) Novell, Inc. 49/1 & 49/3 Garvebhavi Palya, 7th Mile, Hosur Road Bangalore, Karnataka 560068 India Email: jjaimon@novell.com Jim Sermersheim Novell, Inc. 1800 South Novell Place Provo, Utah 84606 US Email: jimse@novell.com Haripriya, et al. Expires July 9, 2007 [Page 24] Internet-Draft LDAP: Dynamic Groups for LDAPv3 January 2007 Full Copyright Statement Copyright (C) The Internet Society (2007). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM 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. Intellectual Property The IETF takes no position regarding the validity or scope of any Intellectual Property Rights 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; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Acknowledgment Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Haripriya, et al. Expires July 9, 2007 [Page 25] PK G]B<u|?6 ?6 9 doc/alt-openldap11-devel/drafts/draft-chu-ldap-csn-xx.txtnu �[��� INTERNET-DRAFT Howard Y. Chu Intended Category: Standard Track Symas Corporation Expires in six months 1 December 2004 Change Sequence Numbers for LDAP <draft-chu-ldap-csn-00.txt> Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. This document is intended to be, after appropriate review and revision, submitted to the RFC Editor as an Standard Track document. Distribution of this memo is unlimited. Technical discussion of this document will take place on the IETF LDAP Extensions mailing list <ldapext@ietf.org>. Please send editorial comments directly to the author <Kurt@OpenLDAP.org>. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as ``work in progress.'' The list of current Internet-Drafts can be accessed at <http://www.ietf.org/ietf/1id-abstracts.txt>. The list of Internet-Draft Shadow Directories can be accessed at <http://www.ietf.org/shadow.html>. Copyright (C) The Internet Society (2004). All Rights Reserved. Please see the Full Copyright section near the end of this document for more information. Abstract This document describes the LDAP/X.500 Change Sequence Number 'CSN' syntax and matching rules and associated attributes. CSNs are used to impose a total ordering upon the sequence of updates applied to a directory. Chu draft-chu-ldap-csn-00 [Page 1] INTERNET-DRAFT LDAP CSN 1 December 2004 1. Background and Intended Use In X.500 Directory Services [X.501], updates to a directory may need to be distributed to multiple servers. The 'modifyTimeStamp' is already defined for recording the time of an update, but it may be inadequate in an environment where multiple servers with loosely synchronized clocks are interoperating. This document describes the 'CSN' syntax which augments a timestamp with additional information to assist in coordinating updates among multiple directory servers. This document describes the 'entryCSN' operational attribute which carries the CSN of the last update applied to an entry and also the 'contextCSN' operational attribute which carries the greatest CSN of all updates applied to a directory context. Directory clients and servers may use these attributes to assist in synchronizing shadowed copies of directory information. This document describes the 'csnMatch' and 'csnOrderingMatch' matching rules corresponding to the 'CSN' syntax. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119]. Schema definitions are provided using LDAP description formats [RFC2252]. Definitions provided here are formatted (line wrapped) for readability. 2. CSN Schema Elements 2.1 CSN Syntax Values in this syntax are encoded according to the following BNF: CSN = timestamp '#' operation-counter '#' replica-id timestamp = <generalizedTimeString as specified in 6.14 of [RFC2252]> operation-counter = 6hex-digit replica-id = 2hex-digit The timestamp SHALL use GMT and SHALL NOT include fractional seconds. The operation-counter is set to zero at the start of each second, and incremented by one for each update operation that occurs within that second. The replica-id is an identifier that represents a specific Replica in a collection of cooperating servers. The following is a LDAP syntax description [RFC2252] suitable for publication in the subschema. ( IANA-ASSIGNED-OID.1 DESC 'CSN' ) Chu draft-chu-ldap-csn-00 [Page 2] INTERNET-DRAFT LDAP CSN 1 December 2004 2.2 'csnMatch' Matching Rule The 'csnMatch' matching rule compares an asserted CSN with a stored CSN for equality. Its semantics are same as the octetStringMatch [X.520][RFC2252] matching rule. The following is a LDAP matching rule description [RFC2252] suitable for publication in the subschema. ( IANA-ASSIGNED-OID.2 NAME 'csnMatch' SYNTAX IANA-ASSIGNED-OID.1 ) 2.3 'csnOrderingMatch' Matching Rule The 'csnOrderingMatch' matching rule compares an asserted CSN with a stored CSN for ordering. Its semantics are the same as the octetStringOrderingMatch [X.520][RFC2252] matching rule. The following is a LDAP matching rule description [RFC2252] suitable for publication in the subschema. ( IANA-ASSIGNED-OID.3 NAME 'csnOrderingMatch' SYNTAX IANA-ASSIGNED-OID.1 ) 2.4. 'entryCSN' attribute The 'entryCSN' operational attribute provides the CSN of the last update applied to the entry. The following is a LDAP attribute type description [RFC2252] suitable for publication in the subschema. ( IANA-ASSIGNED-OID.4 NAME 'entryCSN' DESC 'CSN of the entry content' EQUALITY csnMatch ORDERING csnOrderingMatch Chu draft-chu-ldap-csn-00 [Page 3] INTERNET-DRAFT LDAP CSN 1 December 2004 SYNTAX IANA-ASSIGNED-OID.1 SINGLE-VALUE NO-USER-MODIFICATION USAGE directoryOperation ) Servers SHALL assign a CSN to each entry upon its addition to the directory and provide the entry's CSN as the value of the 'entryCSN' operational attribute. The entryCSN attribute SHOULD be updated upon every update of the entry. 2.5. 'contextCSN' attribute The 'contextCSN' operational attribute provides the greatest CSN of all the updates applied to a context. The following is a LDAP attribute type description [RFC2252] suitable for publication in the subschema. ( IANA-ASSIGNED-OID.5 NAME 'contextCSN' DESC 'the largest committed CSN of a context' EQUALITY csnMatch ORDERING csnOrderingMatch SYNTAX IANA-ASSIGNED-OID.1 SINGLE-VALUE NO-USER-MODIFICATION USAGE directoryOperation ) Servers SHALL record the greatest CSN of all updates applied to a context in the root entry of the context. 3. Security Considerations General LDAP security considerations [RFC3377] apply. 4. IANA Considerations 4.1. Object Identifier Registration It is requested that IANA register upon Standards Action an LDAP Object Identifier for use in this technical specification. Subject: Request for LDAP OID Registration Person & email address to contact for further information: Howard Chu <hyc@symas.com> Specification: RFC XXXX Author/Change Controller: IESG Comments: Identifies the CSN schema elements 4.2. Registration of the csnMatch descriptor It is requested that IANA register upon Standards Action the LDAP 'csnMatch' descriptor. Subject: Request for LDAP Descriptor Registration Descriptor (short name): csnMatch Object Identifier: IANA-ASSIGNED-OID.2 Person & email address to contact for further information: Howard Chu <hyc@symas.com> Usage: Matching Rule Specification: RFC XXXX Author/Change Controller: IESG Chu draft-chu-ldap-csn-00 [Page 4] INTERNET-DRAFT LDAP CSN 1 December 2004 4.3. Registration of the csnOrderingMatch descriptor It is requested that IANA register upon Standards Action the LDAP 'csnOrderingMatch' descriptor. Subject: Request for LDAP Descriptor Registration Descriptor (short name): csnOrderingMatch Object Identifier: IANA-ASSIGNED-OID.3 Person & email address to contact for further information: Howard Chu <hyc@symas.com> Usage: Matching Rule Specification: RFC XXXX Author/Change Controller: IESG 4.4. Registration of the entryCSN descriptor It is requested that IANA register upon Standards Action the LDAP 'entryCSN' descriptor. Subject: Request for LDAP Descriptor Registration Descriptor (short name): entryCSN Object Identifier: IANA-ASSIGNED-OID.4 Person & email address to contact for further information: Howard Chu <hyc@symas.com> Usage: Attribute Type Specification: RFC XXXX Author/Change Controller: IESG 4.5. Registration of the contextCSN descriptor It is requested that IANA register upon Standards Action the LDAP 'contextCSN' descriptor. Subject: Request for LDAP Descriptor Registration Descriptor (short name): contextCSN Object Identifier: IANA-ASSIGNED-OID.5 Person & email address to contact for further information: Howard Chu <hyc@symas.com> Usage: Attribute Type Specification: RFC XXXX Author/Change Controller: IESG 5. Acknowledgments This document is based on prior work from the IETF LDUP working group including the LDAP Replication Architecture [LDUPMODEL] and the LDAP Content Synchronization Operation [LDUPSYNC]. 6. Author's Addresses Howard Y. Chu Symas Corporation <hyc@symas.com> Kurt D. Zeilenga OpenLDAP Foundation <Kurt@OpenLDAP.org> 7. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14 (also RFC 2119), March 1997. Chu draft-chu-ldap-csn-00 [Page 5] INTERNET-DRAFT LDAP CSN 1 December 2004 [RFC2252] Wahl, M., A. Coulbeck, T. Howes, and S. Kille, "Lightweight Directory Access Protocol (v3): Attribute Syntax Definitions", RFC 2252, December 1997. [RFC3377] Hodges, J. and R. Morgan, "Lightweight Directory Access Protocol (v3): Technical Specification", RFC 3377, September 2002. [X.501] International Telecommunication Union - Telecommunication Standardization Sector, "The Directory -- Models," X.501(1993) (also ISO/IEC 9594-2:1994). [X.520] International Telecommunication Union - Telecommunication Standardization Sector, "The Directory: Selected Attribute Types", X.520(1993) (also ISO/IEC 9594-6:1994). [X.680] International Telecommunication Union - Telecommunication Standardization Sector, "Abstract Syntax Notation One (ASN.1) - Specification of Basic Notation", X.680(1997) (also ISO/IEC 8824-1:1998). [LDUPSYNC] Zeilenga, K. and Choi, J-H "LDAP Content Synchronization Operation", draft-zeilenga-ldup-sync-05.txt, a work in progress. 8. Informative References [RFC3383] Zeilenga, K., "IANA Considerations for LDAP", BCP 64 (also RFC 3383), September 2002. [LDUPMODEL] Merrellls, J., Srinivasan, U., and Reed, E., "LDAP Replication Architecture", draft-ietf-ldup-model-09.txt. Intellectual Property Rights The IETF takes no position regarding the validity or scope of any Chu draft-chu-ldap-csn-00 [Page 6] INTERNET-DRAFT LDAP CSN 1 December 2004 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 IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. Copies of claims of rights made available for publication and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementors or users of this specification can be obtained from the IETF Secretariat. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights which may cover technology that may be required to practice this standard. Please address the information to the IETF Executive Director. Full Copyright Copyright (C) The Internet Society (2004). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implmentation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. Chu draft-chu-ldap-csn-00 [Page 7] PK G]l�ۜ�8 �8 @ doc/alt-openldap11-devel/drafts/draft-ietf-ldapext-locate-xx.txtnu �[��� INTERNET-DRAFT Michael P. Armijo <draft-ietf-ldapext-locate-08.txt> Levon Esibov June 5, 2002 Paul Leach Expires: December 5, 2002 Microsoft Corporation R.L. Morgan University of Washington Discovering LDAP Services with DNS 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 Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet- Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Distribution of this memo is unlimited. It is filed as <draft- ietf-ldapext-locate-08.txt>, and expires on December 5, 2002. Please send comments to the authors. Copyright Notice Copyright (C) The Internet Society (2001). All Rights Reserved. Abstract A Lightweight Directory Access Protocol (LDAP) request must be directed to an appropriate server for processing. This document specifies a method for discovering such servers using information in the Domain Name System. Armijo, Esibov, Leach and Morgan [Page 1] INTERNET-DRAFT Discovering LDAP Services with DNS June 5, 2002 1. Introduction The LDAPv3 protocol [1] is designed to be a lightweight access protocol for directory services supporting X.500 models. As a distributed directory service, the complete set of directory information (known as the Directory Information Base) is spread across many different servers. Hence there is the need to determine, when initiating or processing a request, which servers hold the relevant information. In LDAP, the Search, Modify, Add, Delete, ModifyDN, and Compare operations all specify a Distinguished Name (DN) [2] on which the operation is performed. A client, or a server acting on behalf of a client, must be able to determine the server(s) that hold the naming context containing that DN, since that server (or one of that set of servers) must receive and process the request. This determination process is called "server location". To support dynamic distributed operation, the information needed to support server location must be available via lookups done at request processing time, rather than, for example, as static data configured into each client or server. It is possible to maintain the information needed to support server location in the directory itself, and X.500 directory deployments typically do so. In practice, however, this only permits location of servers within a limited X.500-connected set. LDAP-specific methods of maintaining server location information in the directory have not yet been standardized. This document defines an alternative method of managing server location information using the Domain Name System. This method takes advantage of the global deployment of the DNS, by allowing LDAP server location information for any existing DNS domain to be published by creating the records described below. A full discussion of the benefits and drawbacks of the various directory location and naming methods is beyond the scope of this document. RFC 2247[3] defines an algorithm for mapping DNS domain names into DNs. This document defines the inverse mapping, from DNs to DNS domain names, based on the conventions in [3], for use in this server location method. The server location method described in this document is only defined for DNs that can be so mapped, i.e., those DNs that are based on domain names. In practice this is reasonable because many objects of interest are named with domain names, and use of domain-name-based DNs is becoming common. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [9]. Armijo, Esibov, Leach and Morgan [Page 2] INTERNET-DRAFT Discovering LDAP Services with DNS June 5, 2002 2. Mapping Distinguished Names into Domain Names This section defines a method of converting a DN into a DNS domain name for use in the server location method described below. Some DNs cannot be converted into a domain name. Converted DNs result in a fully qualified domain name. The output domain name is initially empty. The DN is processed in right-to-left order (i.e., beginning with the first RDN in the sequence of RDNs). An RDN is able to be converted if it (1) consists of a single AttributeTypeAndValue; (2) the attribute type is "DC"; and (3) the attribute value is non-null. If it can be converted, the attribute value is used as a domain name component (label). The first such value becomes the rightmost (i.e., most significant) domain name component, and successive converted RDN values extend to the left. If an RDN cannot be converted, processing stops. If the output domain name is empty when processing stops, the DN cannot be converted into a domain name. For DN: cn=John Doe,ou=accounting,dc=example,dc=net The client would convert the DC components as defined above into DNS name: example.net The determined DNS name will be submitted as a DNS query using the algorithm defined in section 3. 3. Locating LDAPv3 servers through DNS LDAPv3 server location information is to be stored using DNS Service Location Record (SRV)[5]. The data in a SRV record contains the DNS name of the server that provides the LDAP service, corresponding Port number, and parameters that enable the client to choose an appropriate server from multiple servers according to the algorithm described in [5]. The name of this record has the following format: _<Service>._<Proto>.<Domain>. where <Service> is "ldap", and <Proto> is "tcp". <Domain> is the domain name formed by converting the DN of a naming context mastered by the LDAP Server into a domain name using the algorithm in Section 2. Note that "ldap" is the symbolic name for the LDAP service in Assigned Numbers[6], as required by [5]. Armijo, Esibov, Leach and Morgan [Page 3] INTERNET-DRAFT Discovering LDAP Services with DNS June 5, 2002 Presence of such records enables clients to find the LDAP servers using standard DNS query [4]. A client (or server) seeking an LDAP server for a particular DN converts that DN to a domain name using the algorithm of Section 2, does a SRV record query using the DNS name formed as described in the preceding paragraph, and interprets the response as described in [5] to determine a host (or hosts) to contact. As an example, a client that searches for an LDAP server for the DN "ou=foo,dc=example,dc=net" that supports the TCP protocol will submit a DNS query for a set of SRV records with owner name: _ldap._tcp.example.net. The client will receive the list of SRV records published in DNS that satisfy the requested criteria. The following is an example of such a record: _ldap._tcp.example.net. IN SRV 0 0 389 phoenix.example.net. The set of returned records may contain multiple records in the case where multiple LDAP servers serve the same domain. If there are no matching SRV records available for the converted DN the client SHOULD NOT attempt to 'walk the tree' by removing the least significant portion of the constructed fully qualified domain name. 4. IANA Considerations This document does not require any IANA actions. 5. Security Considerations DNS responses can typically be easily spoofed. Clients using this location method SHOULD ensure, via use of strong security mechanisms, that the LDAP server they contact is the one they intended to contact. See [7] for more information on security threats and security mechanisms. When using LDAP with TLS the client MUST check the server's name, as described in section 3.6 of [RFC 2830]. As specified there, the name the client checks for is the server's name before any potentially insecure transformations, including the SRV record lookup specified in this memo. Thus the name the client MUST check for is the name obtained by doing the mapping step defined in section 2 above. For example, if the DN "cn=John Doe,ou=accounting,dc=example,dc=net" is converted to the DNS name "example.net", the server's name MUST match "example.net". This document describes a method that uses DNS SRV records to discover LDAP servers. All security considerations related to DNS SRV records are inherited by this document. See the security considerations section in [5] for more details. Armijo, Esibov, Leach and Morgan [Page 4] INTERNET-DRAFT Discovering LDAP Services with DNS June 5, 2002 6. References [1] Wahl, M., Howes, T. and S. Kille, "Lightweight Directory Access Protocol(v3)", RFC 2251, December 1997. [2] Wahl, M., Kille, S. and T. Howes, "Lightweight Directory Access Protocol (v3): UTF-8 String Representation of Distinguished Names", RFC 2253, December 1997. [3] Kille, S. and M. Wahl, "Using Domains in LDAP/X.500 Distinguished Names", RFC 2247, January 1998. [4] Mockapetris, P., "DOMAIN NAMES - CONCEPTS AND FACILITIES", RFC 1034, STD 13, November 1987. [5] Gulbrandsen, A., Vixie, P. and L. Esibov, "A DNS RR for specifying the location of services (DNS SRV)", RFC 2782, February 2000. [6] Reynolds, J. and J. Postel, "Assigned Numbers", STD 2, RFC 1700, October 1994. [7] Wahl, M., Alvestrand, H., Hodges, J. and Morgan, R., "Authentication Methods for LDAP", RFC 2829, May 2000. [8] Hodges, J., Morgan, R., Wahl, M., "Lightweight Directory Access Protocol (v3): Extension for Transport Layer Security", RFC 2830, May 2000. [9] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. 7. Authors' Addresses Michael P. Armijo One Microsoft Way Redmond, WA 98052 micharm@microsoft.com Paul Leach One Microsoft Way Redmond, WA 98052 paulle@microsoft.com Levon Esibov One Microsoft Way Redmond, WA 98052 levone@microsoft.com Armijo, Esibov, Leach and Morgan [Page 5] INTERNET-DRAFT Discovering LDAP Services with DNS June 5, 2002 RL "Bob" Morgan University of Washington 4545 15th Ave NE Seattle, WA 98105 US Phone: +1 206 221 3307 EMail: rlmorgan@washington.edu URI: http://staff.washington.edu/rlmorgan/ 8. Intellectual Property Statement 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 IETF's procedures with respect to rights in standards-track and standards- related documentation can be found in BCP-11. Copies of claims of rights made available for publication and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementors or users of this specification can be obtained from the IETF Secretariat. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights which may cover technology that may be required to practice this standard. Please address the information to the IETF Executive Director. 9. Full Copyright Statement Copyright (C) The Internet Society (2001). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. 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 Armijo, Esibov, Leach and Morgan [Page 6] INTERNET-DRAFT Discovering LDAP Services with DNS June 5, 2002 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." 10. Expiration Date This document is filed as <draft-ietf-ldapext-locate-08.txt>, and expires December 5, 2002. Armijo, Esibov, Leach and Morgan [Page 7]PK G]��ت; �; <