< draft-myers-imap-acl-01.txt   draft-myers-imap-acl-02.txt >
Network Working Group J. Myers Network Working Group J. Myers
Internet Draft Carnegie Mellon Internet Draft Carnegie Mellon
Document: draft-myers-imap-acl-01.txt March 1996 Document: draft-myers-imap-acl-02.txt June 1996
IMAP4 ACL extension IMAP4 ACL extension
Status of this Memo Status of this Memo
This document is an Internet Draft. Internet Drafts are working This document is an Internet Draft. Internet Drafts are working
documents of the Internet Engineering Task Force (IETF), its Areas, documents of the Internet Engineering Task Force (IETF), its Areas,
and its Working Groups. Note that other groups may also distribute and its Working Groups. Note that other groups may also distribute
working documents as Internet Drafts. working documents as Internet Drafts.
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``working draft'' or ``work in progress''. ``working draft'' or ``work in progress''.
To learn the current status of any Internet-Draft, please check the To learn the current status of any Internet-Draft, please check the
1id-abstracts.txt listing contained in the Internet-Drafts Shadow 1id-abstracts.txt listing contained in the Internet-Drafts Shadow
Directories on ds.internic.net, nic.nordu.net, ftp.isi.edu, or Directories on ds.internic.net, nic.nordu.net, ftp.isi.edu, or
munnari.oz.au. munnari.oz.au.
A revised version of this draft document will be submitted to the RFC A revised version of this draft document will be submitted to the RFC
editor as a Proposed Standard for the Internet Community. Discussion editor as a Proposed Standard for the Internet Community. Discussion
and suggestions for improvement are requested. This document will and suggestions for improvement are requested. This document will
expire before April 1996. Distribution of this draft is unlimited. expire before December 1996. Distribution of this draft is
unlimited.
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1. Abstract 1. Abstract
The ACL extension of the Internet Message Access Protocol [IMAP4] The ACL extension of the Internet Message Access Protocol [IMAP4]
permits access control lists to be manipulated through the IMAP permits access control lists to be manipulated through the IMAP
protocol. protocol.
2. Conventions Used in this Document 2. Conventions Used in this Document
In examples, "C:" and "S:" indicate lines sent by the client and In examples, "C:" and "S:" indicate lines sent by the client and
server respectively. server respectively.
3. Introduction and Overview 3. Introduction and Overview
The ACL extension is present in any IMAP4 implementation which The ACL extension is present in any IMAP4 implementation which
returns "ACL" as one of the supported capabilities to the CAPABILITY returns "ACL" as one of the supported capabilities to the CAPABILITY
command. command.
An access control list is a set of <identifier,rights> pairs. An access control list is a set of <identifier,rights> pairs.
Identifier is an ASCII string with implementation-defined semantics. Identifier is a US-ASCII string. The identifier anyone is reserved
to refer to the universal identity (all authentications, including
anonymous). All user name strings accepted by the LOGIN or
AUTHENTICATE commands to authenticate to the IMAP server are reserved
as identifiers to refer to the corresponding user. All other
identifier strings have implementation-defined semantics.
Possible variations of identifier interpretation include, but are not Possible variations of identifier interpretation include, but are not
limited to: limited to:
* User names, as specified in the LOGIN command.
* Named groups of users, presumably managed by some * Named groups of users, presumably managed by some
authorization service. authorization service.
* Only allowing identifiers supported by the operating system
(e.g. ``user'', ``group'', and ``other'' for the Unix filesystem)
* A prefix to the identifier specifying an "authentication * A prefix to the identifier specifying an "authentication
type". type".
As an example, an implementation may control posting to a group As an example, an implementation may control posting to a group
based on the contents of the From: header: based on the contents of the From: header:
from$user p from$user p
* Whether the union of rights for matching identifiers are granted * Whether the union of rights for matching identifiers are granted
to a user or whether the rights for the most specific matching to a user or whether the rights for the most specific matching
identifier is granted. identifier is granted.
As an example, for a mailbox with the following ACL: As an example, for a mailbox with the following ACL:
user lrsa user lrsa
group-user-is-in lrsw group-user-is-in lrsw
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One implementation may grant the user 'lrswa' rights, another One implementation may grant the user 'lrswa' rights, another
may only grant the user 'lrsa' rights. may only grant the user 'lrsa' rights.
* A prefix to an identifier name specifying the listed rights * A prefix to an identifier name specifying the listed rights
are to be removed from users who match the prefixed identifier. are to be removed from users who match the prefixed identifier.
As an example, for a mailbox with the following ACL: As an example, for a mailbox with the following ACL:
group-user-is-in lrsw group-user-is-in lrsw
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hierarchy) hierarchy)
d - delete (STORE \DELETED flag, perform EXPUNGE) d - delete (STORE \DELETED flag, perform EXPUNGE)
a - administer (perform SETACL) a - administer (perform SETACL)
An implementation may tie rights together or may force rights to An implementation may tie rights together or may force rights to
always or never be granted. For example, in an implementation that always or never be granted. For example, in an implementation that
uses unix mode bits, the rights "wisd" are tied, the "a" right is uses unix mode bits, the rights "wisd" are tied, the "a" right is
always granted to the owner and is never granted to another user. If always granted to the owner and is never granted to another user. If
rights are tied in an implementation, it should be conservative in rights are tied in an implementation, it should be conservative in
granting rights in response to SETACL commands--unless all rights in granting rights in response to SETACL commands--unless all rights in
a tied set are specified, none should be used. Numeric rights may a tied set are specified, none should be used.
not be tied.
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4. Commands 4. Commands
4.1. SETACL 4.1. SETACL
Arguments: mailbox name Arguments: mailbox name
authentication identifier authentication identifier
access rights access rights
Data: no specific data for this command Data: no specific data for this command
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Arguments: mailbox name Arguments: mailbox name
Data: untagged responses: ACL Data: untagged responses: ACL
Result: OK - getacl completed Result: OK - getacl completed
NO - getacl failure: can't get acl NO - getacl failure: can't get acl
BAD - command unknown or arguments invalid BAD - command unknown or arguments invalid
The GETACL command returns the access control list for mailbox in The GETACL command returns the access control list for mailbox in
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an untagged ACL reply. an untagged ACL reply.
Example: C: A002 GETACL INBOX Example: C: A002 GETACL INBOX
S: * ACL INBOX Fred rwipslda S: * ACL INBOX Fred rwipslda
S: A002 OK Getacl complete S: A002 OK Getacl complete
4.4. MYRIGHTS 4.4. LISTRIGHTS
Arguments: mailbox name
authentication identifier
Data: untagged responses: LISTRIGHTS
Result: OK - listrights completed
NO - listrights failure: can't get rights list
BAD - command unknown or arguments invalid
Example: C: a001 LISTRIGHTS ~/Mail/saved smith
S: * LISTRIGHTS ~/Mail/saved smith la r swicd
S: a001 OK Listrights completed
C: a005 LISTRIGHTS archive.imap anyone
S: * LISTRIGHTS archive.imap anyone "" l r s w i p c d a 0 1
2 3 4 5 6 7 8 9
S: a005 OK Listrights completed
The LISTRIGHTS command takes a mailbox name and an identifier and
returns information about what rights may be granted to the
4.5. MYRIGHTS
Arguments: mailbox name Arguments: mailbox name
Data: untagged responses: MYRIGHTS Data: untagged responses: MYRIGHTS
Result: OK - myrights completed Result: OK - myrights completed
NO - myrights failure: can't get rights NO - myrights failure: can't get rights
BAD - command unknown or arguments invalid BAD - command unknown or arguments invalid
Example: C: A003 MYRIGHTS INBOX
S: * MYRIGHTS INBOX rwipslda
S: A003 OK Myrights complete
The MYRIGHTS command returns the set of rights that the user has The MYRIGHTS command returns the set of rights that the user has
to mailbox in an untagged MYRIGHTS reply. to mailbox in an untagged MYRIGHTS reply.
Example: C: A003 MYRIGHTS INBOX
S: * MYRIGHTS INBOX rwipslda
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S: A003 OK Myrights complete
5. Responses 5. Responses
5.1. ACL 5.1. ACL
Data: mailbox name Data: mailbox name
zero or more identifier rights pairs zero or more identifier rights pairs
The ACL response occurs as a result of a GETACL command. The The ACL response occurs as a result of a GETACL command. The
first string is the mailbox name for which this ACL entry applies. first string is the mailbox name for which this ACL entry applies.
This is followed by zero or more pairs of strings, each pair This is followed by zero or more pairs of strings, each pair
contains the identifier for which the entry applies followed by contains the identifier for which the entry applies followed by
the set of rights that the identifier has. the set of rights that the identifier has.
5.2. MYRIGHTS 5.2. LISTRIGHTS
Data: mailbox name
identifier
required rights
list of optional rights
The LISTRIGHTS response occurs as a result of a LISTRIGHTS
command. The first two strings are the mailbox name and
identifier for which this rights list applies. Following the
identifier is a string containing the (possibly empty) set of
rights the identifier will always be granted in the mailbox.
Following this are zero or more strings each containing a set of
rights the identifier may be granted in the mailbox. Rights
mentioned in the same string are tied together--either all must be
granted to the identifier in the mailbox or none may be granted.
The same right may not be listed more than once in the LISTRIGHTS
command.
5.3. MYRIGHTS
Data: mailbox name Data: mailbox name
rights rights
The MYRIGHTS response occurs as a result of a MYRIGHTS command. The MYRIGHTS response occurs as a result of a MYRIGHTS command.
The first string is the mailbox name for which this ACL entry The first string is the mailbox name for which this ACL entry
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applies. The second string is the set of rights that the client applies. The second string is the set of rights that the client
has. has.
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6. Formal Syntax 6. Formal Syntax
The following syntax specification uses the augmented Backus-Naur The following syntax specification uses the augmented Backus-Naur
Form (BNF) notation as specified in [RFC-822] as modified by [IMAP4]. Form (BNF) notation as specified in [RFC-822] as modified by [IMAP4].
Non-terminals referenced but not defined below are as defined by Non-terminals referenced but not defined below are as defined by
[IMAP4]. [IMAP4].
Except as noted otherwise, all alphabetic characters are Except as noted otherwise, all alphabetic characters are
case-insensitive. The use of upper or lower case characters to case-insensitive. The use of upper or lower case characters to
define token strings is for editorial clarity only. Implementations define token strings is for editorial clarity only. Implementations
MUST accept these strings in a case-insensitive fashion. MUST accept these strings in a case-insensitive fashion.
acl_data ::= "ACL" SPACE mailbox *(SPACE identifier SPACE rights) acl_data ::= "ACL" SPACE mailbox *(SPACE identifier SPACE rights)
deleteacl ::= "DELETEACL" SPACE mailbox SPACE identifier deleteacl ::= "DELETEACL" SPACE mailbox SPACE identifier
getacl ::= "GETACL" SPACE mailbox getacl ::= "GETACL" SPACE mailbox
identifier ::= astring identifier ::= astring
listrights ::= "LISTRIGHTS" SPACE mailbox SPACE identifier
listrights_data ::= "LISTRIGHTS" SPACE mailbox SPACE identifier
SPACE rights *(SPACE rights)
myrights ::= "MYRIGHTS" SPACE mailbox myrights ::= "MYRIGHTS" SPACE mailbox
myrights_data ::= "MYRIGHTS" SPACE mailbox SPACE rights myrights_data ::= "MYRIGHTS" SPACE mailbox SPACE rights
rights ::= astring rights ::= astring
setacl ::= "SETACL" SPACE mailbox SPACE identifier SPACE rights setacl ::= "SETACL" SPACE mailbox SPACE identifier SPACE rights
7. References 7. References
[IMAP4] Crispin, M., "Internet Message Access Protocol - Version 4", [IMAP4] Crispin, M., "Internet Message Access Protocol - Version 4",
RFC 1730, University of Washington, December 1994. RFC 1730, University of Washington, December 1994.
[RFC-822] Crocker, D., "Standard for the Format of ARPA Internet Text [RFC-822] Crocker, D., "Standard for the Format of ARPA Internet Text
Messages", STD 11, RFC 822. Messages", STD 11, RFC 822.
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8. Security Considerations 8. Security Considerations
An implementation must make sure the ACL commands themselves do not An implementation must make sure the ACL commands themselves do not
give information about mailboxes with appropriately restricted ACL's. give information about mailboxes with appropriately restricted ACL's.
For example, a GETACL command on a mailbox for which the user has For example, a GETACL command on a mailbox for which the user has
insufficient rights should not admit the mailbox exists, much less insufficient rights should not admit the mailbox exists, much less
return the mailbox's ACL. return the mailbox's ACL.
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9. Author's Address 9. Author's Address
John G. Myers John G. Myers
Carnegie-Mellon University Carnegie-Mellon University
5000 Forbes Ave. 5000 Forbes Ave.
Pittsburgh PA, 15213-3890 Pittsburgh PA, 15213-3890
Email: jgm+@cmu.edu Email: jgm+@cmu.edu
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Table of Contents Table of Contents
Status of this Memo ............................................... i Status of this Memo ............................................... i
1. Abstract ..................................................... 2 1. Abstract ..................................................... 2
2. Conventions Used in this Document ............................ 2 2. Conventions Used in this Document ............................ 2
3. Introduction and Overview .................................... 2 3. Introduction and Overview .................................... 2
4. Commands ..................................................... 4 4. Commands ..................................................... 4
4.1. SETACL ....................................................... 4 4.1. SETACL ....................................................... 4
4.2. DELETEACL .................................................... 4 4.2. DELETEACL .................................................... 4
4.3. GETACL ....................................................... 4 4.3. GETACL ....................................................... 4
4.4. MYRIGHTS ..................................................... 5 4.4. LISTRIGHTS ................................................... 5
5. Responses .................................................... 5 4.5. MYRIGHTS ..................................................... 5
5.1. ACL .......................................................... 5 5. Responses .................................................... 6
5.2. MYRIGHTS ..................................................... 5 5.1. ACL .......................................................... 6
6. Formal Syntax ................................................ 6 5.2. LISTRIGHTS ................................................... 6
7. References ................................................... 6 5.3. MYRIGHTS ..................................................... 6
8. Security Considerations ...................................... 6 6. Formal Syntax ................................................ 7
9. Author's Address ............................................. 7 7. References ................................................... 7
8. Security Considerations ...................................... 8
9. Author's Address ............................................. 8
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