draft-ietf-imapext-2086upd-06.txt   draft-ietf-imapext-2086upd-07.txt 
Network Working Group A. Melnikov
Internet Draft Editor Individual A. Melnikov
Document: draft-ietf-imapext-2086upd-06.txt April 2005 Internet-Draft Isode Ltd.
Obsoletes: 2086 Obsoletes: 2086 (if approved) June 12, 2005
Expires: October 2005 Expires: December 14, 2005
IMAP4 ACL extension IMAP4 ACL extension
draft-ietf-imapext-2086upd-07
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Abstract Abstract
The ACL (Access Control List) extension (RFC 2086) of the Internet The ACL (Access Control List) extension (RFC 2086) of the Internet
Message Access Protocol (IMAP) permits mailbox access control Message Access Protocol (IMAP) permits mailbox access control lists
lists to be retrieved and manipulated through the IMAP protocol. to be retrieved and manipulated through the IMAP protocol.
This document is a revision of RFC 2086. It defines several new This document is a revision of RFC 2086. It defines several new
access control rights and clarifies which rights are required for access control rights and clarifies which rights are required for
different IMAP commands. different IMAP commands.
1. Conventions Used in this Document 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.
In all examples "/" character is used as hierarchy separator. In all examples "/" character is used as hierarchy separator.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [KEYWORDS]. document are to be interpreted as described in RFC 2119 [KEYWORDS].
The phrase "ACL server" is just a short cut for saying "IMAP server The phrase "ACL server" is just a short cut for saying "IMAP server
that supports ACL extension as defined in this document". that supports ACL extension as defined in this document".
2. Introduction and Overview Table of Contents
1. Introduction and Overview . . . . . . . . . . . . . . . . . . 4
2. Access Control . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1 Standard rights . . . . . . . . . . . . . . . . . . . . . 5
2.1.1 Obsolete rights . . . . . . . . . . . . . . . . . . . 6
2.2 Rights defined in RFC 2086 . . . . . . . . . . . . . . . . 9
3. Access control management commands and responses . . . . . . . 9
3.1 SETACL command . . . . . . . . . . . . . . . . . . . . . . 9
3.2 DELETEACL command . . . . . . . . . . . . . . . . . . . . 10
3.3 GETACL command . . . . . . . . . . . . . . . . . . . . . . 11
3.4 LISTRIGHTS command . . . . . . . . . . . . . . . . . . . . 11
3.5 MYRIGHTS command . . . . . . . . . . . . . . . . . . . . . 12
3.6 ACL response . . . . . . . . . . . . . . . . . . . . . . . 12
3.7 LISTRIGHTS response . . . . . . . . . . . . . . . . . . . 12
3.8 MYRIGHTS response . . . . . . . . . . . . . . . . . . . . 13
4. Rights required to perform different IMAP4rev1 commands . . . 13
5. Other considerations . . . . . . . . . . . . . . . . . . . . . 17
5.1 Additional requirements and Implementation notes . . . . . 17
5.1.1 Servers . . . . . . . . . . . . . . . . . . . . . . . 17
5.1.2 Clients . . . . . . . . . . . . . . . . . . . . . . . 19
5.2 Mapping of ACL rights to READ-WRITE and READ-ONLY
response codes . . . . . . . . . . . . . . . . . . . . . . 19
6. Security Considerations . . . . . . . . . . . . . . . . . . . 21
7. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . 21
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23
9. Internationalization Considerations . . . . . . . . . . . . . 23
A. Changes since RFC 2086 . . . . . . . . . . . . . . . . . . . . 23
B. Compatibility with RFC 2086 . . . . . . . . . . . . . . . . . 24
C. Known deficiencies . . . . . . . . . . . . . . . . . . . . . . 24
D. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 25
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 25
10.1 Normative References . . . . . . . . . . . . . . . . . . . 25
10.2 Informative References . . . . . . . . . . . . . . . . . . 26
Author's Address . . . . . . . . . . . . . . . . . . . . . . . 26
Intellectual Property and Copyright Statements . . . . . . . . 27
1. Introduction and Overview
The ACL (Access Control List) extension of the Internet Message The ACL (Access Control List) extension of the Internet Message
Access Protocol [IMAP4] permits mailbox access control lists to be Access Protocol [IMAP4] permits mailbox access control lists to be
retrieved and manipulated through the IMAP protocol. retrieved and manipulated through the IMAP protocol.
This document is a revision of RFC 2086. It tries to clarify This document is a revision of RFC 2086 [RFC2086]. It tries to
different ambiguities in RFC 2086, in particular use of UTF-8 clarify different ambiguities in RFC 2086, in particular use of UTF-8
[UTF-8] in identifiers, which rights are required for different IMAP4 [UTF-8] in identifiers, which rights are required for different IMAP4
commands; how READ-WRITE/READ-ONLY response codes are related to ACL. commands; how READ-WRITE/READ-ONLY response codes are related to ACL.
3. Access Control 2. Access Control
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.
A server implementation conformant to this document MUST also return A server implementation conformant to this document MUST also return
rights (see below) not defined in section 3.2 in the "RIGHTS=" rights (see below) not defined in Section 2.2 in the "RIGHTS="
capability. capability.
An access control list is a set of <identifier,rights> pairs. An access control list is a set of <identifier,rights> pairs. An ACL
An ACL applies to a mailbox name. applies to a mailbox name.
Identifier is a UTF-8 [UTF-8] string. The identifier "anyone" is Identifier is a UTF-8 [UTF-8] string. The identifier "anyone" is
reserved to refer to the universal identity (all authentications, reserved to refer to the universal identity (all authentications,
including anonymous). All user name strings accepted by the LOGIN or including anonymous). All user name strings accepted by the LOGIN or
AUTHENTICATE commands to authenticate to the IMAP server are reserved AUTHENTICATE commands to authenticate to the IMAP server are reserved
as identifiers for the corresponding users. Identifiers starting as identifiers for the corresponding users. Identifiers starting
with a dash ("-") are reserved for "negative rights", described with a dash ("-") are reserved for "negative rights", described
below. All other identifier strings are interpreted in an below. All other identifier strings are interpreted in an
implementation-defined manner. implementation-defined manner.
Rights is a string listing a (possibly empty) set of alphanumeric Rights is a string listing a (possibly empty) set of alphanumeric
characters, each character listing a set of operations which is being characters, each character listing a set of operations which is being
controlled. Lowercase letters are reserved for "standard" rights, controlled. Lowercase letters are reserved for "standard" rights,
listed in section 3.1. (Note that for compatibility with deployed listed in Section 2.1. (Note that for compatibility with deployed
clients and servers uppercase rights are not allowed). The set of clients and servers uppercase rights are not allowed). The set of
standard rights can only be extended by a standards-track document. standard rights can only be extended by a standards-track document.
Digits are reserved for implementation or site defined rights. Digits are reserved for implementation or site defined rights.
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 to particular identifiers. For example, always or never be granted to particular identifiers. For example,
in an implementation that uses UNIX mode bits, the rights "swite" are in an implementation that uses UNIX mode bits, the rights "swite" are
tied, the "a" right is always granted to the owner of a mailbox and tied, the "a" right is always granted to the owner of a mailbox and
is never granted to another user. If rights are tied in an is never granted to another user. If rights are tied in an
implementation, the implementation must be conservative in granting implementation, the implementation must be conservative in granting
rights in response to SETACL commands--unless all rights in a tied rights in response to SETACL commands--unless all rights in a tied
set are specified, none of that set should be included in the ACL set are specified, none of that set should be included in the ACL
entry for that identifier. A client can discover the set of rights entry for that identifier. A client can discover the set of rights
which may be granted to a given identifier in the ACL for a given which may be granted to a given identifier in the ACL for a given
mailbox name by using the LISTRIGHTS command. mailbox name by using the LISTRIGHTS command.
It is possible for multiple identifiers in an access control list to It is possible for multiple identifiers in an access control list to
apply to a given user. For apply to a given user. For example, an ACL may include rights to be
example, an ACL may include rights to be granted to the identifier granted to the identifier matching the user, one or more
matching the user, one or more implementation-defined identifiers implementation-defined identifiers matching groups which include the
matching groups which include the user, and/or the identifier user, and/or the identifier "anyone". How these rights are combined
"anyone". How these rights are combined to determine the user's to determine the user's access is implementation-defined. An
access is implementation-defined. An implementation may choose, for implementation may choose, for example, to use the union of the
example, to use the union of the rights granted to the applicable rights granted to the applicable identifiers. An implementation may
identifiers. An implementation may instead choose, for example, to instead choose, for example, to only use those rights granted to the
only use those rights granted to the most specific identifier present most specific identifier present in the ACL. A client can determine
in the ACL. A client can determine the set of rights granted to the the set of rights granted to the logged-in user for a given mailbox
logged-in user for a given mailbox name by using the MYRIGHTS name by using the MYRIGHTS command.
command.
When an identifier in an ACL starts with a dash ("-"), that indicates When an identifier in an ACL starts with a dash ("-"), that indicates
that associated rights are to be removed from the identifier that is that associated rights are to be removed from the identifier that is
prefixed by the dash. This is referred to as a "negative right". prefixed by the dash. This is referred to as a "negative right".
This differs from DELETEACL in that a negative right is added to the This differs from DELETEACL in that a negative right is added to the
ACL, and is a part of the calculation of the rights. ACL, and is a part of the calculation of the rights.
Let's assume that an identifier "fred" refers to a user with login Let's assume that an identifier "fred" refers to a user with login
"fred". If the identifier "-fred" is granted the "w" right, "fred". If the identifier "-fred" is granted the "w" right, that
that indicates that the "w" right is to be removed from users indicates that the "w" right is to be removed from users matching the
matching the identifier "fred", even though the user "fred" might identifier "fred", even though the user "fred" might have the "w"
have the "w" right as a consequence of some other identifier in right as a consequence of some other identifier in the ACL. A
the ACL. A DELETEACL of "fred" simply deletes the identifier "fred" DELETEACL of "fred" simply deletes the identifier "fred" from the
from the ACL; it does not affect any rights that the user "fred" ACL; it does not affect any rights that the user "fred" may get from
may get from another entry in the ACL, in particular it doesn't another entry in the ACL, in particular it doesn't affect rights
affect rights granted to the identifier "-fred". granted to the identifier "-fred".
Server implementations are not required to support "negative right" Server implementations are not required to support "negative right"
identifiers. identifiers.
3.1. Standard rights 2.1 Standard rights
The currently defined standard rights are (note that the list below The currently defined standard rights are (note that the list below
doesn't list all commands that use a particular right): doesn't list all commands that use a particular right):
l - lookup (mailbox is visible to LIST/LSUB commands, SUBSCRIBE mailbox) l - lookup (mailbox is visible to LIST/LSUB commands, SUBSCRIBE
mailbox)
r - read (SELECT the mailbox, perform STATUS) r - read (SELECT the mailbox, perform STATUS)
s - keep seen/unseen information across sessions (set or clear \SEEN flag s - keep seen/unseen information across sessions (set or clear
via STORE, also set \SEEN during APPEND/COPY/FETCH BODY[...]) \SEEN flag via STORE, also set \SEEN during APPEND/COPY/
w - write (set or clear flags other than \SEEN and \DELETED via STORE, FETCH BODY[...])
also set them during APPEND/COPY) w - write (set or clear flags other than \SEEN and \DELETED via
STORE, also set them during APPEND/COPY)
i - insert (perform APPEND, COPY into mailbox) i - insert (perform APPEND, COPY into mailbox)
p - post (send mail to submission address for mailbox, p - post (send mail to submission address for mailbox,
not enforced by IMAP4 itself) not enforced by IMAP4 itself)
k - create mailboxes (CREATE new sub-mailboxes in any k - create mailboxes (CREATE new sub-mailboxes in any
implementation-defined hierarchy, parent mailbox for the new implementation-defined hierarchy, parent mailbox for the new
mailbox name in RENAME) mailbox name in RENAME)
x - delete mailbox (DELETE mailbox, old mailbox name in RENAME) x - delete mailbox (DELETE mailbox, old mailbox name in RENAME)
t - delete messages (set or clear \DELETED flag via STORE, set \DELETED flag t - delete messages (set or clear \DELETED flag via STORE, set
during APPEND/COPY) \DELETED flag during APPEND/COPY)
e - perform EXPUNGE and expunge as a part of CLOSE. e - perform EXPUNGE and expunge as a part of CLOSE.
a - administer (perform SETACL/DELETEACL/GETACL) a - administer (perform SETACL/DELETEACL/GETACL)
3.1.1. Obsolete rights 2.1.1 Obsolete rights
Due to ambiguity in RFC 2086 some existing RFC 2086 server implementations Due to ambiguity in RFC 2086 some existing RFC 2086 server
use the "c" right to control the DELETE command. Others chose to use the implementations use the "c" right to control the DELETE command.
"d" right to control the DELETE command. Others chose to use the "d" right to control the DELETE command. For
For the former group, let's define the "create" right as union of the "k" the former group, let's define the "create" right as union of the "k"
and "x" rights, and the "delete" right as union of the "e" and "t" rights. and "x" rights, and the "delete" right as union of the "e" and "t"
For the latter group, let's define the "create" rights as a synonym to the rights. For the latter group, let's define the "create" rights as a
"k" right, and the "delete" right as union of the "e", "t" and "x" rights. synonym to the "k" right, and the "delete" right as union of the "e",
"t" and "x" rights.
For compatibility with RFC 2086 this section defines two virtual rights For compatibility with RFC 2086 this section defines two virtual
"d" and "c". rights "d" and "c".
If a client includes the "d" right in a rights list, then it MUST be If a client includes the "d" right in a rights list, then it MUST be
treated as if the client had included every member of the "delete" right. treated as if the client had included every member of the "delete"
(It is not an error for a client to specify both the "d" right and right. (It is not an error for a client to specify both the "d"
one or more members of the "delete" right, but the effect is no different right and one or more members of the "delete" right, but the effect
than if just the "d" right or all members of the "delete" right had been is no different than if just the "d" right or all members of the
specified). "delete" right had been specified).
When any of the "delete" member rights is set in a list of When any of the "delete" member rights is set in a list of rights,
rights, the server MUST also include the "d" right when returning the server MUST also include the "d" right when returning the list in
the list in a MYRIGHTS or ACL response. This is so to enable older clients a MYRIGHTS or ACL response. This is so to enable older clients
conforming to RFC 2086 to work with newer servers. (*) conforming to RFC 2086 to work with newer servers. (*)
Example: C: A001 SETACL INBOX/Drafts David lrswida Example: C: A001 SeTacl INBOX/Drafts David lrswida
S: A001 OK Setacl complete S: A001 OK Setacl complete
The client has specified the "d" right in the SETACL command above and it The client has specified the "d" right in the SETACL command above
expands to "et" on the server: and it expands to "et" on the server:
C: A002 GETACL INBOX/Drafts C: A002 getacl INBOX/Drafts
S: * ACL INBOX Fred rwipslxetda David lrswideta S: * ACL INBOX Fred rwipslxetda David lrswideta
S: A002 OK Getacl complete S: A002 OK Getacl complete
If the identifier specified in the LISTRIGHTS command can be If the identifier specified in the LISTRIGHTS command can be granted
granted any of the "delete" member rights on a mailbox, then the server any of the "delete" member rights on a mailbox, then the server MUST
MUST include the "d" right in the corresponding LISTRIGHTS response. (*) include the "d" right in the corresponding LISTRIGHTS response. (*)
If the member rights aren't tied to non-member rights, then the "d" right If the member rights aren't tied to non-member rights, then the "d"
is returned by itself in the LISTRIGHTS response. If any of the member rights right is returned by itself in the LISTRIGHTS response. If any of
needs to be tied to one (or more) non-member right, then the "d" right and all the member rights needs to be tied to one (or more) non-member right,
of the member rights need to be tied to the same non-member right(s) (**). then the "d" right and all of the member rights need to be tied to
the same non-member right(s) (**).
If a client includes the "c" right in a rights list, then it MUST be If a client includes the "c" right in a rights list, then it MUST be
treated as if the client had included every member of the "create" right. treated as if the client had included every member of the "create"
(It is not an error for a client to specify both the "c" right and right. (It is not an error for a client to specify both the "c"
one or more members of the "create" right, but the effect is no different right and one or more members of the "create" right, but the effect
than if just the "c" right or all members of the "create" right had been is no different than if just the "c" right or all members of the
specified). "create" right had been specified).
When any of the "create" member rights is set in a list of When any of the "create" member rights is set in a list of rights,
rights, the server MUST also include the "c" right when returning the server MUST also include the "c" right when returning the list in
the list in a MYRIGHTS or ACL response. This is so to enable older clients a MYRIGHTS or ACL response. This is so to enable older clients
conforming to RFC 2086 to work with newer servers. (*) conforming to RFC 2086 to work with newer servers. (*)
Example: C: A003 SETACL INBOX/Drafts Byron lrswikda Example: C: A003 Setacl INBOX/Drafts Byron lrswikda
S: A001 OK Setacl complete S: A001 OK Setacl complete
C: A002 GETACL INBOX/Drafts C: A002 getAcl INBOX/Drafts
S: * ACL INBOX Fred rwipslxeta Byron lrswikcdeta S: * ACL INBOX Fred rwipslxeta Byron lrswikcdeta
S: A002 OK Getacl complete S: A002 OK Getacl complete
The client has specified the "d" right in the SETACL command above and it The client has specified the "d" right in the SETACL command above
expands to "et" on the server: As the client has specified the "k" right and it expands to "et" on the server: As the client has specified
(which is a member of the "c" right), the server also returns the "c" right. the "k" right (which is a member of the "c" right), the server also
returns the "c" right.
If the identifier specified in the LISTRIGHTS command can be If the identifier specified in the LISTRIGHTS command can be granted
granted any of the "create" member rights on a mailbox, then the server any of the "create" member rights on a mailbox, then the server MUST
MUST include the "c" right in the corresponding LISTRIGHTS response. (*) include the "c" right in the corresponding LISTRIGHTS response. (*)
If the member rights aren't tied to non-member rights, then the "c" right If the member rights aren't tied to non-member rights, then the "c"
is returned by itself in the LISTRIGHTS response. If any of the member rights right is returned by itself in the LISTRIGHTS response. If any of
needs to be tied to one (or more) non-member right, then the "c" right and all the member rights needs to be tied to one (or more) non-member right,
of the member rights need to be tied to the same non-member right(s) (**). then the "c" right and all of the member rights need to be tied to
the same non-member right(s) (**).
Example: The server that ties the rights as follows Example: The server that ties the rights as follows
lr s w i p k x t lr s w i p k x t
and c=k and c=k
will return: will return:
S: * LISTRIGHTS archive/imap anyone "" lr s w i p k x t c d S: * LISTRIGHTS archive/imap anyone ""
lr s w i p k x t c d
Example: The server that ties the rights as follows Example: The server that ties the rights as follows
lr s w i p k xte lr s w i p k xte
and c=k and c=k
will return: will return:
S: * LISTRIGHTS archive/imap anyone "" lr s w i p k xte c d S: * LISTRIGHTS archive/imap anyone ""
lr s w i p k xte c d
Example: The server that ties the rights as follows Example: The server that ties the rights as follows
lr s w i p k x te lr s w i p k x te
and c=k and c=k
will return: will return:
S: * LISTRIGHTS archive/imap anyone "" lr s w i p k c x te d S: * LISTRIGHTS archive/imap anyone ""
lr s w i p k c x te d
Example: The server that ties the rights as follows Example: The server that ties the rights as follows
lr swte i p k x lr swte i p k x
and c=kx and c=kx
will return: will return:
S: * LISTRIGHTS archive/imap anyone "" lr swted i p k x c S: * LISTRIGHTS archive/imap anyone ""
lr swted i p k x c
(*) Clients conforming to this document MUST ignore the virtual "d" and "c" (*) Clients conforming to this document MUST ignore the virtual "d"
rights in MYRIGHTS, ACL and LISTRIGHTS responses. and "c" rights in MYRIGHTS, ACL and LISTRIGHTS responses.
(**) The IMAPEXT Working Group has debated this issue in great length (**) The IMAPEXT Working Group has debated this issue in great length
and after reviewing existing ACL implementations concluded that this is and after reviewing existing ACL implementations concluded that this
a reasonable restriction. is a reasonable restriction.
3.2. Rights defined in RFC 2086. 2.2 Rights defined in RFC 2086
The "RIGHTS=" capability MUST NOT include any of the rights defined The "RIGHTS=" capability MUST NOT include any of the rights defined
in RFC 2086: "l", "r", "s", "w", "i", "p", "a", "c", "d", and the digits in RFC 2086: "l", "r", "s", "w", "i", "p", "a", "c", "d", and the
("0" .. "9"). digits ("0" .. "9").
4. Access control management commands and responses 3. Access control management commands and responses
Servers, when processing a command that has an identifier Servers, when processing a command that has an identifier as a
as a parameter (i.e. any of SETACL, DELETEACL and LISTRIGHTS commands), parameter (i.e. any of SETACL, DELETEACL and LISTRIGHTS commands),
SHOULD first prepare the received identifier using "SASLprep" profile SHOULD first prepare the received identifier using "SASLprep" profile
[SASLprep] of the "stringprep" algorithm [StringPrep]. If the [SASLprep] of the "stringprep" algorithm [Stringprep]. If the
preparation of the identifier fails or results in an empty string, the preparation of the identifier fails or results in an empty string,
server MUST refuse to perform the command with a BAD response. the server MUST refuse to perform the command with a BAD response.
4.1. SETACL command 3.1 SETACL command
Arguments: mailbox name Arguments: mailbox name
identifier identifier
access right modification access right modification
Data: no specific data for this command Data: no specific data for this command
Result: OK - setacl completed Result: OK - setacl completed
NO - setacl failure: can't set acl NO - setacl failure: can't set acl
BAD - arguments invalid BAD - arguments invalid
The SETACL command changes the access control list on the The SETACL command changes the access control list on the specified
specified mailbox so that the specified identifier is granted mailbox so that the specified identifier is granted permissions as
permissions as specified in the third argument. specified in the third argument.
The third argument is a string containing an optional plus ("+") The third argument is a string containing an optional plus ("+") or
or minus ("-") prefix, followed by zero or more rights characters. minus ("-") prefix, followed by zero or more rights characters. If
If the string starts with a plus, the following rights are added the string starts with a plus, the following rights are added to any
to any existing rights for the identifier. If the string starts existing rights for the identifier. If the string starts with a
with a minus, the following rights are removed from any existing minus, the following rights are removed from any existing rights for
rights for the identifier. If the string does not start with a the identifier. If the string does not start with a plus or minus,
plus or minus, the rights replace any existing rights for the the rights replace any existing rights for the identifier.
identifier.
Note that an unrecognized right MUST cause the command to return Note that an unrecognized right MUST cause the command to return the
the BAD response. In particular, server MUST NOT silently ignore BAD response. In particular, server MUST NOT silently ignore
unrecognized rights. unrecognized rights.
Example: C: A001 GETACL INBOX/Drafts Example: C: A001 GETACL INBOX/Drafts
S: * ACL INBOX/Drafts Fred rwipslxetad Chris lrswi S: * ACL INBOX/Drafts Fred rwipslxetad Chris lrswi
S: A001 OK Getacl complete S: A001 OK Getacl complete
C: A002 SETACL INBOX/Drafts Chris +cda C: A002 SETACL INBOX/Drafts Chris +cda
S: A002 OK Setacl complete S: A002 OK Setacl complete
C: A003 GETACL INBOX/Drafts C: A003 GETACL INBOX/Drafts
S: * ACL INBOX/Drafts Fred rwipslxetad Chris lrswicdakxet S: * ACL INBOX/Drafts Fred rwipslxetad Chris lrswicdakxet
S: A003 OK Getacl complete S: A003 OK Getacl complete
C: A035 SETACL INBOX/Drafts John lrQswicda C: A035 SETACL INBOX/Drafts John lrQswicda
S: A035 BAD Uppercase rights are not allowed S: A035 BAD Uppercase rights are not allowed
C: A036 SETACL INBOX/Drafts John lrqswicda C: A036 SETACL INBOX/Drafts John lrqswicda
S: A036 BAD The q right is not supported S: A036 BAD The q right is not supported
4.2. DELETEACL command 3.2 DELETEACL command
Arguments: mailbox name Arguments: mailbox name
identifier identifier
Data: no specific data for this command Data: no specific data for this command
Result: OK - deleteacl completed Result: OK - deleteacl completed
NO - deleteacl failure: can't delete acl NO - deleteacl failure: can't delete acl
BAD - arguments invalid BAD - arguments invalid
The DELETEACL command removes any <identifier,rights> pair for the The DELETEACL command removes any <identifier,rights> pair for the
specified identifier from the access control list for the specified specified identifier from the access control list for the specified
mailbox. mailbox.
Example: C: B001 GETACL INBOX Example: C: B001 getacl INBOX
S: * ACL INBOX Fred rwipslxetad -Fred wetd $team w S: * ACL INBOX Fred rwipslxetad -Fred wetd $team w
S: B001 OK Getacl complete S: B001 OK Getacl complete
C: B002 DELETEACL INBOX Fred C: B002 DeleteAcl INBOX Fred
S: B002 OK Deleteacl complete S: B002 OK Deleteacl complete
C: B003 GETACL INBOX C: B003 GETACL INBOX
S: * ACL INBOX -Fred wetd $team w S: * ACL INBOX -Fred wetd $team w
S: B003 OK Getacl complete S: B003 OK Getacl complete
4.3. GETACL command 3.3 GETACL command
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 - arguments invalid BAD - arguments invalid
The GETACL command returns the access control list for mailbox in The GETACL command returns the access control list for mailbox in an
an untagged ACL response. untagged ACL response.
Some implementations MAY permit multiple forms of an Some implementations MAY permit multiple forms of an identifier to
identifier to reference the same IMAP account. Usually, such reference the same IMAP account. Usually, such implementations will
implementations will have a canonical form that is stored internally. have a canonical form that is stored internally. An ACL response
An ACL response caused by an GETACL command MAY include a caused by an GETACL command MAY include a canonicalized form of the
canonicalized form of the identifier which might be identifier which might be different from the one used in the
different from the one used in the corresponding SETACL command. corresponding SETACL command.
Example: C: A002 GETACL INBOX Example: C: A002 GETACL INBOX
S: * ACL INBOX Fred rwipsldexta S: * ACL INBOX Fred rwipsldexta
S: A002 OK Getacl complete S: A002 OK Getacl complete
4.4. LISTRIGHTS command 3.4 LISTRIGHTS command
Arguments: mailbox name Arguments: mailbox name
identifier identifier
Data: untagged responses: LISTRIGHTS Data: untagged responses: LISTRIGHTS
Result: OK - listrights completed Result: OK - listrights completed
NO - listrights failure: can't get rights list NO - listrights failure: can't get rights list
BAD - arguments invalid BAD - arguments invalid
The LISTRIGHTS command takes a mailbox name and an identifier and The LISTRIGHTS command takes a mailbox name and an identifier and
returns information about what rights can be granted to the identifier returns information about what rights can be granted to the
in the ACL for the mailbox. identifier in the ACL for the mailbox.
Some implementations MAY permit multiple forms of an Some implementations MAY permit multiple forms of an identifier to
identifier to reference the same IMAP account. Usually, such reference the same IMAP account. Usually, such implementations will
implementations will have a canonical form that is stored internally. have a canonical form that is stored internally. A LISTRIGHTS
A LISTRIGHTS response caused by a LISTRIGHTS command MUST always response caused by a LISTRIGHTS command MUST always return the same
return the same form of an identifier as specified form of an identifier as specified by the client. This is to allow
by the client. This is to allow the client to correlate the response the client to correlate the response with the command.
with the command.
Example: C: a001 LISTRIGHTS ~/Mail/saved smith Example: C: a001 LISTRIGHTS ~/Mail/saved smith
S: * LISTRIGHTS ~/Mail/saved smith la r swicdkxte S: * LISTRIGHTS ~/Mail/saved smith la r swicdkxte
S: a001 OK Listrights completed S: a001 OK Listrights completed
Example: C: a005 LISTRIGHTS archive/imap anyone Example: C: a005 listrights archive/imap anyone
S: * LISTRIGHTS archive.imap anyone "" l r s w i p k x t S: * LISTRIGHTS archive.imap anyone ""
e c d a 0 1 2 3 4 5 6 7 8 9 l r s w i p k x t e c d a 0 1 2 3 4 5 6 7 8 9
S: a005 Listrights successful S: a005 Listrights successful
4.5. MYRIGHTS command 3.5 MYRIGHTS command
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 - arguments invalid BAD - arguments invalid
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
to mailbox in an untagged MYRIGHTS reply. mailbox in an untagged MYRIGHTS reply.
Example: C: A003 MYRIGHTS INBOX Example: C: A003 MYRIGHTS INBOX
S: * MYRIGHTS INBOX rwiptsldaex S: * MYRIGHTS INBOX rwiptsldaex
S: A003 OK Myrights complete S: A003 OK Myrights complete
4.6. ACL response 3.6 ACL response
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 first The ACL response occurs as a result of a GETACL command. The first
string is the mailbox name for which this ACL applies. This is string is the mailbox name for which this ACL applies. This is
followed by zero or more pairs of strings, each pair contains the followed by zero or more pairs of strings, each pair contains the
identifier for which the entry applies followed by the set of identifier for which the entry applies followed by the set of rights
rights that the identifier has. that the identifier has.
Section 3.1.1 details additional server requirements related to handling Section 2.1.1 details additional server requirements related to
of the virtual "d" and "c" rights. handling of the virtual "d" and "c" rights.
4.7. LISTRIGHTS response 3.7 LISTRIGHTS response
Data: mailbox name Data: mailbox name
identifier identifier
required rights required rights
list of optional rights list of optional rights
The LISTRIGHTS response occurs as a result of a LISTRIGHTS command.
The LISTRIGHTS response occurs as a result of a LISTRIGHTS The first two strings are the mailbox name and identifier for which
command. The first two strings are the mailbox name and identifier this rights list applies. Following the identifier is a string
for which this rights list applies. Following the identifier is a containing the (possibly empty) set of rights the identifier will
string containing the (possibly empty) set of rights the always be granted in the mailbox.
identifier will always be granted in the mailbox.
Following this are zero or more strings each containing a set of Following this are zero or more strings each containing a set of
rights the identifier can be granted in the mailbox. Rights rights the identifier can be granted in the mailbox. Rights
mentioned in the same string are tied together. The server MUST mentioned in the same string are tied together. The server MUST
either grant all tied rights to the identifier in the mailbox or either grant all tied rights to the identifier in the mailbox or
grant none. Section 3.1.1 details additional server requirements grant none. Section 2.1.1 details additional server requirements
related to handling of the virtual "d" and "c" rights. related to handling of the virtual "d" and "c" rights.
The same right MUST NOT be listed more than once in the LISTRIGHTS The same right MUST NOT be listed more than once in the LISTRIGHTS
command. command.
4.8. MYRIGHTS response 3.8 MYRIGHTS response
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
The first string is the mailbox name for which these rights apply. first string is the mailbox name for which these rights apply. The
The second string is the set of rights that the client has. second string is the set of rights that the client has.
Section 3.1.1 details additional server requirements related to handling Section 2.1.1 details additional server requirements related to
of the virtual "d" and "c" rights. handling of the virtual "d" and "c" rights.
5. Rights required to perform different IMAP4rev1 commands 4. Rights required to perform different IMAP4rev1 commands
Before executing a command an ACL compliant server MUST check which rights Before executing a command an ACL compliant server MUST check which
are required to perform it. This section groups command by functions rights are required to perform it. This section groups command by
they perform and list the rights required. It also gives the detailed functions they perform and list the rights required. It also gives
description of any special processing required. the detailed description of any special processing required.
For the purpose of this section the UID counterpart of a command is For the purpose of this section the UID counterpart of a command is
considered to be the same command, e.g. both UID COPY and COPY commands considered to be the same command, e.g. both UID COPY and COPY
require the same set of rights. commands require the same set of rights.
The table below summarizes different rights or their combinations that are The table below summarizes different rights or their combinations
required in order to perform different IMAP operations. As it is not always that are required in order to perform different IMAP operations. As
possible to express complex right checking and interactions, the description it is not always possible to express complex right checking and
after the table should be used as the primary reference. interactions, the description after the table should be used as the
primary reference.
+---------------------+---+---+---+---+---+---+---+---+---+---+-----+------+ +-------------------+---+---+---+---+---+---+---+---+---+---+---+---+
| Operations\Rights | l | r | s | w | i | k | x | t | e | a | Any | None | |Operations\Rights | l | r | s | w | i | k | x | t | e | a |Any|Non|
+---------------------+---+---+---+---+---+---+---+---+---+---+-----+------+ +-------------------+---+---+---+---+---+---+---+---+---+---+---+---+
| commands in authenticated state | | commands in authenticated state |
+--------------------------------------------------------------------------+ +-------------------------------------------------------------------+
| LIST | + | | | | | | | | | | | | | LIST | + | | | | | | | | | | | |
| SUBSCRIBE | * | | | | | | | | | | | * | | SUBSCRIBE | * | | | | | | | | | | | * |
| UNSUBSCRIBE | | | | | | | | | | | | + | | UNSUBSCRIBE | | | | | | | | | | | | + |
| LSUB | * | | | | | | | | | | | * | | LSUB | * | | | | | | | | | | | * |
| CREATE (for parent) | | | | | | + | | | | | | | | CREATE (for parent) | | | | | | + | | | | | | |
| DELETE | | | | | | | + | ? | ? | | | | | DELETE | | | | | | | + | ? | ? | | | |
| RENAME | | | | | | + | + | | | | | | | RENAME | | | | | | + | + | | | | | |
|SELECT/EXAMINE/STATUS| | + | | | | | | | | | | | |SELECT/EXAMINE/ | | + | | | | | | | | | | |
| STATUS | | + | | | | | | | | | | |
| SETACL/DELETEACL | | | | | | | | | | + | | | | SETACL/DELETEACL | | | | | | | | | | + | | |
| GETACL/LISTRIGHTS | | | | | | | | | | + | | | | GETACL/LISTRIGHTS | | | | | | | | | | + | | |
| MYRIGHTS | | | | | | | | | | | + | | | MYRIGHTS | | | | | | | | | | | + | |
| APPEND | | | ? | ? | + | | | ? | | | | | | APPEND | | | ? | ? | + | | | ? | | | | |
+--------------------------------------------------------------------------+ +-------------------------------------------------------------------+
| commands in selected state | | commands in selected state |
+--------------------------------------------------------------------------+ +-------------------------------------------------------------------+
| APPEND | | | ? | ? | + | | | ? | | | | | | COPY | | | ? | ? | + | | | ? | | | | |
| EXPUNGE/CLOSE | | | | | | | | | + | | | | | EXPUNGE/CLOSE | | | | | | | | | + | | | |
| FETCH | | | ? | | | | | | | | | | | FETCH | | | ? | | | | | | | | | |
| STORE flags | | | ? | ? | | | | ? | | | | | | STORE flags | | | ? | ? | | | | ? | | | | |
+---------------------+---+---+---+---+---+---+---+---+---+---+-----+------+ +-------------------+---+---+---+---+---+---+---+---+---+---+---+---+
Note: for all commands in the selected state the "r" is implied, because
it is required to SELECT/EXAMINE a mailbox. Servers are not required Note: for all commands in the selected state the "r" is implied,
to check presence of the "r" right once a mailbox is successfully because it is required to SELECT/EXAMINE a mailbox. Servers are not
selected. required to check presence of the "r" right once a mailbox is
successfully selected.
Legend: Legend:
+ - The right is required + - The right is required
* - Only one of the rights marked with * is required (see description below) * - Only one of the rights marked with * is required
(see description below)
? - The right is OPTIONAL (see description below) ? - The right is OPTIONAL (see description below)
"Any" - at least one of the "l", "r", "i", "k", "x", "a" rights is "Any" - at least one of the "l", "r", "i", "k", "x", "a" rights is
required required
"None" - No rights required to perform the command "Non" - No rights required to perform the command
Listing and subscribing/unsubscribing mailboxes: Listing and subscribing/unsubscribing mailboxes:
LIST - "l" right is required. However, unlike other commands (e.g. SELECT) LIST - "l" right is required. However, unlike other commands
the server MUST NOT return a NO response if it can't list a mailbox. (e.g. SELECT) the server MUST NOT return a NO response if it
can't list a mailbox.
Note that if the user has "l" right to a mailbox "A/B", but not to
its parent mailbox "A", the LIST command should behave as if the
mailbox "A" doesn't exist, for example:
Note that if the user has "l" right to a mailbox "A/B", but not to its parent
mailbox "A", the LIST command should behave as if the mailbox "A" doesn't exist,
for example:
C: A777 LIST "" * C: A777 LIST "" *
S: * LIST (\NoInferiors) "/" "A/B" S: * LIST (\NoInferiors) "/" "A/B"
S: * LIST () "/" "C" S: * LIST () "/" "C"
S: * LIST (\NoInferiors) "/" "C/D" S: * LIST (\NoInferiors) "/" "C/D"
S: A777 OK LIST completed S: A777 OK LIST completed
SUBSCRIBE - "l" right is required only if the server checks for mailbox existence SUBSCRIBE - "l" right is required only if the server checks for
when performing SUBSCRIBE. mailbox existence when performing SUBSCRIBE.
UNSUBSCRIBE - no rights required to perform this operation. UNSUBSCRIBE - no rights required to perform this operation.
LSUB - "l" right is required only if the server checks for mailbox existence when LSUB - "l" right is required only if the server checks for mailbox
performing SUBSCRIBE. However, unlike other commands (e.g. SELECT) existence when performing SUBSCRIBE. However, unlike other
the server MUST NOT return a NO response if it can't list a subscribed commands (e.g. SELECT) the server MUST NOT return a NO response
mailbox. if it can't list a subscribed mailbox.
Mailbox management: Mailbox management:
CREATE - "k" right on a nearest existing parent mailbox. When a new CREATE - "k" right on a nearest existing parent mailbox. When a
mailbox is created it SHOULD inherit the ACL from the parent new mailbox is created it SHOULD inherit the ACL from the parent
mailbox (if one exists) in the defined hierarchy. mailbox (if one exists) in the defined hierarchy.
DELETE - "x" right on the mailbox. Note that some servers don't allow DELETE - "x" right on the mailbox. Note that some servers don't
to delete a non-empty mailbox. If this is the case, the user allow to delete a non-empty mailbox. If this is the case, the
would also need "r", "e" and "t" rights, in order to open the user would also need "r", "e" and "t" rights, in order to open the
mailbox and empty it. mailbox and empty it.
The DELETE command MUST delete the ACL associated with the The DELETE command MUST delete the ACL associated with the deleted
deleted mailbox. mailbox.
RENAME - Moving a mailbox from one parent to another requires the "x" right
on the mailbox itself and the "k" right for the new parent.
For example, if the user wants to rename mailbox named "A/B/C" to
"D/E", the user must have the "x" right for the mailbox "A/B/C"
and the "k" right for the mailbox "D".
RENAME - Moving a mailbox from one parent to another requires the
"x" right on the mailbox itself and the "k" right for the new
parent. For example, if the user wants to rename mailbox named
"A/B/C" to "D/E", the user must have the "x" right for the mailbox
"A/B/C" and the "k" right for the mailbox "D".
The RENAME command SHOULD NOT change the ACLs on the renamed The RENAME command SHOULD NOT change the ACLs on the renamed
mailbox and submailboxes. mailbox and submailboxes.
Copying or appending messages: Copying or appending messages:
Before performing a COPY/APPEND command the server MUST check if
Before performing a COPY/APPEND command the server MUST check if the the user has "i" right for the target mailbox. If the user
user has "i" right for the target mailbox. If the user doesn't have "i" doesn't have "i" right, the operation fails. Otherwise for each
right, the operation fails. Otherwise for each copied/appended message copied/appended message the server MUST check if the user has "t"
the server MUST check if the user has right - when the message has \Deleted flag set "s" right - when
"t" right - when the message has \Deleted flag set the message has \Seen flag set "w" right for all other message
"s" right - when the message has \Seen flag set flags. Only when the user has a particular right the
"w" right for all other message flags. corresponding flags are stored for the newly created message. The
Only when the user has a particular right the corresponding flags are server MUST NOT fail a COPY/APPEND if the user has no rights to
stored for the newly created message. The server MUST NOT fail set a particular flag.
a COPY/APPEND if the user has no rights to set a particular flag.
Example: C: A003 MYRIGHTS TargetMailbox Example: C: A003 MYRIGHTS TargetMailbox
S: * MYRIGHTS TargetMailbox rwis S: * MYRIGHTS TargetMailbox rwis
S: A003 OK Myrights complete S: A003 OK Myrights complete
C: A004 FETCH 1:3 (FLAGS) C: A004 FETCH 1:3 (FLAGS)
S: * 1 FETCH (FLAGS (\Draft \Deleted) S: * 1 FETCH (FLAGS (\Draft \Deleted)
S: * 2 FETCH (FLAGS (\Answered) S: * 2 FETCH (FLAGS (\Answered)
S: * 3 FETCH (FLAGS ($Forwarded \Seen) S: * 3 FETCH (FLAGS ($Forwarded \Seen)
S: A004 OK Fetch Completed S: A004 OK Fetch Completed
C: A005 COPY 1:3 TargetMailbox C: A005 COPY 1:3 TargetMailbox
S: A005 OK Copy completed S: A005 OK Copy completed
C: A006 SELECT TargetMailbox C: A006 SELECT TargetMailbox
... ...
S: A006 Select Completed S: A006 Select Completed
Let's assume that the copied messages received message numbers 77:79. Let's assume that the copied messages received message numbers
77:79.
C: A007 FETCH 77:79 (FLAGS) C: A007 FETCH 77:79 (FLAGS)
S: * 77 FETCH (FLAGS (\Draft)) S: * 77 FETCH (FLAGS (\Draft))
S: * 78 FETCH (FLAGS (\Answered)) S: * 78 FETCH (FLAGS (\Answered))
S: * 79 FETCH (FLAGS ($Forwarded \Seen)) S: * 79 FETCH (FLAGS ($Forwarded \Seen))
S: A007 OK Fetch Completed S: A007 OK Fetch Completed
\Deleted flag was lost on COPY, as the user has no "t" right in the \Deleted flag was lost on COPY, as the user has no "t" right in
target mailbox. the target mailbox.
If the MYRIGHTS command with the tag A003 would have returned: If the MYRIGHTS command with the tag A003 would have returned:
S: * MYRIGHTS TargetMailbox rsti S: * MYRIGHTS TargetMailbox rsti
the response from the FETCH with the tag A007 would have been: the response from the FETCH with the tag A007 would have been:
C: A007 FETCH 77:79 (FLAGS) C: A007 FETCH 77:79 (FLAGS)
S: * 77 FETCH (FLAGS (\Deleted)) S: * 77 FETCH (FLAGS (\Deleted))
S: * 78 FETCH (FLAGS ()) S: * 78 FETCH (FLAGS ())
S: * 79 FETCH (FLAGS (\Seen)) S: * 79 FETCH (FLAGS (\Seen))
S: A007 OK Fetch Completed S: A007 OK Fetch Completed
skipping to change at line 648 skipping to change at page 16, line 48
S: * MYRIGHTS TargetMailbox rsti S: * MYRIGHTS TargetMailbox rsti
the response from the FETCH with the tag A007 would have been: the response from the FETCH with the tag A007 would have been:
C: A007 FETCH 77:79 (FLAGS) C: A007 FETCH 77:79 (FLAGS)
S: * 77 FETCH (FLAGS (\Deleted)) S: * 77 FETCH (FLAGS (\Deleted))
S: * 78 FETCH (FLAGS ()) S: * 78 FETCH (FLAGS ())
S: * 79 FETCH (FLAGS (\Seen)) S: * 79 FETCH (FLAGS (\Seen))
S: A007 OK Fetch Completed S: A007 OK Fetch Completed
In the latter case \Answered, $Forwarded and \Draft flags were lost In the latter case \Answered, $Forwarded and \Draft flags were
on COPY, as the user has no "w" right in the target mailbox. lost on COPY, as the user has no "w" right in the target mailbox.
Expunging the selected mailbox: Expunging the selected mailbox:
EXPUNGE - "e" right on the selected mailbox. EXPUNGE - "e" right on the selected mailbox.
CLOSE - "e" right on the selected mailbox. If the server is unable to CLOSE - "e" right on the selected mailbox. If the server is
expunge the mailbox because the user doesn't have the "e" right, unable to expunge the mailbox because the user doesn't have the
the server MUST ignore expunge request, close the mailbox "e" right, the server MUST ignore expunge request, close the
and return tagged OK response. mailbox and return tagged OK response.
Fetch information about a mailbox and its messages: Fetch information about a mailbox and its messages:
SELECT/EXAMINE/STATUS - "r" right on the mailbox. SELECT/EXAMINE/STATUS - "r" right on the mailbox.
FETCH - A FETCH request that implies setting \Seen flag MUST NOT set it, FETCH - A FETCH request that implies setting \Seen flag MUST NOT
if the current user doesn't have "s" right. set it, if the current user doesn't have "s" right.
Changing flags: Changing flags:
STORE - the server MUST check if the user has STORE - the server MUST check if the user has "t" right - when the
"t" right - when the user modifies \Deleted flag user modifies \Deleted flag "s" right - when the user modifies
"s" right - when the user modifies \Seen flag \Seen flag "w" right for all other message flags. STORE operation
"w" right for all other message flags. SHOULD NOT fail if the user has rights to modify at least one flag
STORE operation SHOULD NOT fail if the user has rights to modify at least specified in the STORE, as the tagged NO response to a STORE
one flag specified in the STORE, as the tagged NO response to a STORE
command is not handled very well by deployed clients. command is not handled very well by deployed clients.
Changing ACLs: Changing ACLs:
SETACL/DELETEACL - "a" right on the mailbox. SETACL/DELETEACL - "a" right on the mailbox.
Reading ACLs: Reading ACLs:
GETACL - "a" right on the mailbox. GETACL - "a" right on the mailbox.
MYRIGHTS - any of the following rights is required to perform MYRIGHTS - any of the following rights is required to perform the
the operation: "l", "r", "i", "k", "x", "a". operation: "l", "r", "i", "k", "x", "a".
LISTRIGHTS - "a" right on the mailbox. LISTRIGHTS - "a" right on the mailbox.
6. Other considerations 5. Other considerations
6.1. Additional requirements and Implementation notes 5.1 Additional requirements and Implementation notes
6.1.1. Servers 5.1.1 Servers
This document defines an additional capability that is used to announce This document defines an additional capability that is used to
the list of extra rights (excluding the ones defined in the RFC 2086) announce the list of extra rights (excluding the ones defined in the
supported by the server. The set of rights MUST include "t", "e", "x" RFC 2086) supported by the server. The set of rights MUST include
and "k". Note that the extra rights can appear in any order. "t", "e", "x" and "k". Note that the extra rights can appear in any
order.
Example: C: 1 capability Example: C: 1 capability
S: * CAPABILITY IMAP4REV1 STARTTLS LITERAL+ ACL RIGHTS=texk S: * CAPABILITY IMAP4REV1 STARTTLS LITERAL+
ACL RIGHTS=texk
S: 1 OK completed S: 1 OK completed
Any server implementing an ACL extension MUST accurately reflect the current Any server implementing an ACL extension MUST accurately reflect the
user's rights in FLAGS and PERMANENTFLAGS responses. current user's rights in FLAGS and PERMANENTFLAGS responses.
Example: C: A142 SELECT INBOX Example: C: A142 SELECT INBOX
S: * 172 EXISTS S: * 172 EXISTS
S: * 1 RECENT S: * 1 RECENT
S: * OK [UNSEEN 12] Message 12 is first unseen S: * OK [UNSEEN 12] Message 12 is first unseen
S: * OK [UIDVALIDITY 3857529045] UIDs valid S: * OK [UIDVALIDITY 3857529045] UIDs valid
S: * OK [UIDNEXT 4392] Predicted next UID S: * OK [UIDNEXT 4392] Predicted next UID
S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft)
S: * OK [PERMANENTFLAGS (\Seen \Answered \Flagged \*)] Limited S: * OK [PERMANENTFLAGS (\Seen \Answered \Flagged \*)] L
S: A142 OK [READ-WRITE] SELECT completed S: A142 OK [READ-WRITE] SELECT completed
C: A143 MYRIGHTS INBOX C: A143 MYRIGHTS INBOX
S: * MYRIGHTS INBOX lrwis S: * MYRIGHTS INBOX lrwis
S: A143 OK completed S: A143 OK completed
Note that in order to get better performance the client MAY pipeline Note that in order to get better performance the client MAY pipeline
SELECT and MYRIGHTS commands: SELECT and MYRIGHTS commands:
C: A142 SELECT INBOX C: A142 SELECT INBOX
C: A143 MYRIGHTS INBOX C: A143 MYRIGHTS INBOX
S: * 172 EXISTS S: * 172 EXISTS
S: * 1 RECENT S: * 1 RECENT
S: * OK [UNSEEN 12] Message 12 is first unseen S: * OK [UNSEEN 12] Message 12 is first unseen
S: * OK [UIDVALIDITY 3857529045] UIDs valid S: * OK [UIDVALIDITY 3857529045] UIDs valid
S: * OK [UIDNEXT 4392] Predicted next UID S: * OK [UIDNEXT 4392] Predicted next UID
S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft)
S: * OK [PERMANENTFLAGS (\Seen \Answered \Flagged \*)] Limited S: * OK [PERMANENTFLAGS (\Seen \Answered \Flagged \*)] L
S: A142 OK [READ-WRITE] SELECT completed S: A142 OK [READ-WRITE] SELECT completed
S: * MYRIGHTS INBOX lrwis S: * MYRIGHTS INBOX lrwis
S: A143 OK completed S: A143 OK completed
Servers MAY cache the rights a user has on a mailbox when the mailbox Servers MAY cache the rights a user has on a mailbox when the mailbox
is selected, so that if a client's rights on a mailbox are changed with is selected, so that if a client's rights on a mailbox are changed
SETACL or DELETEACL, commands specific to the selected state (e.g., STORE, with SETACL or DELETEACL, commands specific to the selected state
EXPUNGE) might not reflect the changed rights until the mailbox is (e.g., STORE, EXPUNGE) might not reflect the changed rights until the
re-selected. If the server checks the rights on each command, then it SHOULD mailbox is re-selected. If the server checks the rights on each
send FLAGS and PERMANENTFLAGS responses if they have changed. command, then it SHOULD send FLAGS and PERMANENTFLAGS responses if
If such server detects that the user no longer has read access to the they have changed. If such server detects that the user no longer
mailbox, it MAY send an untagged BYE response and close connection. has read access to the mailbox, it MAY send an untagged BYE response
It MAY also refuse to execute all commands specific to the selected state and close connection. It MAY also refuse to execute all commands
until the mailbox is closed, however server implementors should note that specific to the selected state until the mailbox is closed, however
most clients don't handle NO responses very well. server implementors should note that most clients don't handle NO
responses very well.
An ACL server MAY modify one or more ACL for one or more identifier as a An ACL server MAY modify one or more ACL for one or more identifier
side effect of modifying the ACL specified in a SETACL/DELETEACL. as a side effect of modifying the ACL specified in a SETACL/
If the server does that it MUST send untagged ACL response(s) to notify the DELETEACL. If the server does that it MUST send untagged ACL
client about the changes made. response(s) to notify the client about the changes made.
An ACL server implementation MUST treat received ACL modification commands An ACL server implementation MUST treat received ACL modification
as a possible ambiguity with respect to subsequent commands affected by the commands as a possible ambiguity with respect to subsequent commands
ACL, as described in section 5.5 of [IMAP4]. Hence a pipeline affected by the ACL, as described in section 5.5 of [IMAP4]. Hence a
SETACL + MYRIGHTS is an ambiguity with respect to the server, meaning that pipeline SETACL + MYRIGHTS is an ambiguity with respect to the
the server must execute the SETACL command to completion before the MYRIGHTS. server, meaning that the server must execute the SETACL command to
However, clients are permitted to send such a pipeline. completion before the MYRIGHTS. However, clients are permitted to
send such a pipeline.
6.1.2. Clients 5.1.2 Clients
The following requirement is put on clients in order to allow for The following requirement is put on clients in order to allow for
future extensibility. future extensibility. A client implementation that allows a user to
A client implementation that allows a user to read and update ACLs MUST read and update ACLs MUST preserve unrecognized rights that it
preserve unrecognized rights that it doesn't allow the user to change. doesn't allow the user to change. I.e., if the client
I.e., if the client
1) can read ACLs 1) can read ACLs
and and
2) can update ACLs 2) can update ACLs
but but
3) doesn't allow the user to change the rights the client doesn't recognize, 3) doesn't allow the user to change the rights the client doesn't
then it MUST preserve unrecognized rights. recognize, then it MUST preserve unrecognized rights.
Otherwise the client could risk unintentionally removing permissions Otherwise the client could risk unintentionally removing permissions
it doesn't understand. it doesn't understand.
6.2. Mapping of ACL rights to READ-WRITE and READ-ONLY response codes 5.2 Mapping of ACL rights to READ-WRITE and READ-ONLY response codes
A particular ACL server implementation MAY allow "shared multiuser A particular ACL server implementation MAY allow "shared multiuser
access" to some mailboxes. "Shared multiuser access" to a mailbox means access" to some mailboxes. "Shared multiuser access" to a mailbox
that multiple different users are able to access the same mailbox, means that multiple different users are able to access the same
if they have proper access rights. "Shared multiuser access" to the mailbox, if they have proper access rights. "Shared multiuser
mailbox doesn't mean that the ACL for the mailbox is currently set access" to the mailbox doesn't mean that the ACL for the mailbox is
to allow access by multiple users. Let's denote a "shared multiuser currently set to allow access by multiple users. Let's denote a
write access" as a "shared multiuser access" when a user can be "shared multiuser write access" as a "shared multiuser access" when a
granted flag modification rights (any of "w", "s" or "t"). user can be granted flag modification rights (any of "w", "s" or
"t").
Section 5 describes which rights are required for modifying different flags. Section 4 describes which rights are required for modifying different
flags.
If the ACL server implements some flags as shared for a mailbox (i.e., If the ACL server implements some flags as shared for a mailbox
the ACL for the mailbox MAY be set up so that changes to those flags are (i.e., the ACL for the mailbox MAY be set up so that changes to those
visible to another user), let's call the set of rights associated with these flags are visible to another user), let's call the set of rights
flags (as described in Section 5) for that mailbox collectively as associated with these flags (as described in Section 4) for that
"shared flag rights". Note that "shared flag rights" set MAY be different mailbox collectively as "shared flag rights". Note that "shared flag
for different mailboxes. rights" set MAY be different for different mailboxes.
If the server doesn't support "shared multiuser write access" to a If the server doesn't support "shared multiuser write access" to a
mailbox or doesn't implement shared flags on the mailbox, "shared flag mailbox or doesn't implement shared flags on the mailbox, "shared
rights" for the mailbox is defined to be the empty set. flag rights" for the mailbox is defined to be the empty set.
Example 1: Mailbox "banan" allows "shared multiuser write access" and Example 1: Mailbox "banan" allows "shared multiuser write access" and
implements flags \Deleted, \Answered and $MDNSent as implements flags \Deleted, \Answered and $MDNSent as
shared flags. "Shared flag rights" for the mailbox "banan" shared flags. "Shared flag rights" for the mailbox "banan"
is a set containing flags "t" (because system flag \Deleted is a set containing flags "t" (because system flag
requires "t" right) and "w" (because both \Answered and \Deleted requires "t" right) and "w" (because both
$MDNSent require "w" right). \Answered and $MDNSent require "w" right).
Example 2: Mailbox "apple" allows "shared multiuser write access" and Example 2: Mailbox "apple" allows "shared multiuser write access" and
implements \Seen system flag as shared flag. "Shared flag implements \Seen system flag as shared flag. "Shared flag
rights" for the mailbox "apple" contains "s" right, rights" for the mailbox "apple" contains "s" right,
because system flag \Seen requires "s" right. because system flag \Seen requires "s" right.
Example 3: Mailbox "pear" allows "shared multiuser write access" and Example 3: Mailbox "pear" allows "shared multiuser write access" and
implements flags \Seen, \Draft as shared flags. "Shared flag implements flags \Seen, \Draft as shared flags. "Shared
rights" for the mailbox "apple" is a set containing flags "s" flag rights" for the mailbox "apple" is a set containing
(because system flag \Seen requires "s" right) and "w" flags "s" (because system flag \Seen requires "s" right)
(because system flag \Draft requires "w" right). and "w" (because system flag \Draft requires "w" right).
The server MUST include a READ-ONLY response code in the tagged OK
response to a SELECT command if none of the following rights is
granted to the current user:
The server MUST include a READ-ONLY response code in the tagged OK response to
a SELECT command if none of the following rights is granted to the
current user:
"i", "e" and "shared flag rights"*. "i", "e" and "shared flag rights"*.
The server SHOULD include a READ-WRITE response code in the tagged OK response
if at least one of the "i", "e" or "shared flag rights"* is granted to the
current user.
* - Note that a future extension to this document can extend the list of The server SHOULD include a READ-WRITE response code in the tagged OK
rights that causes the server to return the READ-WRITE response code. response if at least one of the "i", "e" or "shared flag rights"* is
granted to the current user.
* - Note that a future extension to this document can extend the list
of rights that causes the server to return the READ-WRITE response
code.
Example 1 (continued): The user that has "lrs" rights for the mailbox Example 1 (continued): The user that has "lrs" rights for the mailbox
"banan". The server returns READ-ONLY response "banan". The server returns READ-ONLY response
code on SELECT, as none of "iewt" rights is code on SELECT, as none of "iewt" rights is
granted to the user. granted to the user.
Example 2 (continued): The user that has "rit" rights for the mailbox Example 2 (continued): The user that has "rit" rights for the mailbox
"apple". The server returns READ-WRITE response "apple". The server returns READ-WRITE
code on SELECT, as the user has "i" right. response code on SELECT, as the user has "i"
right.
Example 3 (continued): The user that has "rset" rights for the mailbox Example 3 (continued): The user that has "rset" rights for the
"pear". The server returns READ-WRITE response mailbox "pear". The server returns READ-WRITE
code on SELECT, as the user has "e" and "s" rights. response code on SELECT, as the user has "e"
and "s" rights.
7. Security Considerations 6. 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, when a user agent executes a GETACL command on a mailbox For example, when a user agent executes a GETACL command on a mailbox
that the user has no permission to LIST, the server would respond to that that the user has no permission to LIST, the server would respond to
request with the same error that would be used if the mailbox did not exist, that request with the same error that would be used if the mailbox
thus revealing no existence information, much less the mailbox's ACL. did not exist, thus revealing no existence information, much less the
mailbox's ACL.
IMAP clients implementing ACL that are able to modify ACLs SHOULD IMAP clients implementing ACL that are able to modify ACLs SHOULD
warn a user that wants to give full access (or even just the "a" right) warn a user that wants to give full access (or even just the "a"
to the special identifier "anyone". right) to the special identifier "anyone".
8. Formal Syntax 7. Formal Syntax
Formal syntax is defined using ABNF [ABNF], extending the ABNF rules Formal syntax is defined using ABNF [ABNF], extending the ABNF rules
in section 9 of [IMAP]. The IMAP4 ABNF should be imported first before in section 9 of [IMAP4]. Elements not defined here can be found in
attempting to validate these rules. the [ABNF] and [IMAP4].
Except as noted otherwise, all alphabetic characters are Except as noted otherwise, all alphabetic characters are case-
case-insensitive. The use of upper or lower case characters to insensitive. The use of upper or lower case characters to define
define token strings is for editorial clarity only. Implementations token strings is for editorial clarity only. Implementations MUST
MUST accept these strings in a case-insensitive fashion. accept these strings in a case-insensitive fashion.
LOWER-ALPHA = %x61-7A ;; a-z LOWER-ALPHA = %x61-7A ;; a-z
acl-data = "ACL" SP mailbox *(SP identifier SP acl-data = "ACL" SP mailbox *(SP identifier SP
rights) rights)
capability =/ rights-capa capability =/ rights-capa
;;capability is defined in [IMAP4] ;;capability is defined in [IMAP4]
command-auth =/ setacl / deleteacl / getacl / command-auth =/ setacl / deleteacl / getacl /
skipping to change at line 899 skipping to change at page 22, line 42
;; +rights to add, -rights to remove ;; +rights to add, -rights to remove
;; rights to replace ;; rights to replace
myrights = "MYRIGHTS" SP mailbox myrights = "MYRIGHTS" SP mailbox
myrights-data = "MYRIGHTS" SP mailbox SP rights myrights-data = "MYRIGHTS" SP mailbox SP rights
new-rights = 1*LOWER-ALPHA new-rights = 1*LOWER-ALPHA
;; MUST include "t", "e", "x" and "k". ;; MUST include "t", "e", "x" and "k".
;; MUST NOT include standard rights listed ;; MUST NOT include standard rights listed
;; in section 3.2 ;; in section 2.2
rights = astring rights = astring
;; only lowercase ASCII letters and digits ;; only lowercase ASCII letters and digits
;; are allowed. ;; are allowed.
rights-capa = "RIGHTS=" new-rights rights-capa = "RIGHTS=" new-rights
;; RIGHTS=... capability ;; RIGHTS=... capability
setacl = "SETACL" SP mailbox SP identifier setacl = "SETACL" SP mailbox SP identifier
SP mod-rights SP mod-rights
9. IANA Considerations 8. IANA Considerations
IMAP4 capabilities are registered by publishing a standards track or IMAP4 capabilities are registered by publishing a standards track or
IESG approved experimental RFC. The registry is currently located IESG approved experimental RFC. The registry is currently located
at: at:
http://www.iana.org/assignments/imap4-capabilities http://www.iana.org/assignments/imap4-capabilities
This document defines the RIGHTS= IMAP capability. IANA is requested This document defines the RIGHTS= IMAP capability. IANA is requested
to add this capability to the registry. to add this capability to the registry.
10. Internationalization Considerations 9. Internationalization Considerations
Section 4 states requirements on servers regarding internationalization
of identifiers.
11. References
11.1. Normative References
[KEYWORDS] Bradner, "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, Harvard University, March 1997.
[ABNF] Crocker, Overell, "Augmented BNF for Syntax Specifications:
ABNF", RFC 2234, Internet Mail Consortium, Demon Internet Ltd,
November 1997.
[IMAP4] Crispin, M., "Internet Message Access Protocol - Version
4rev1", RFC 3501, University of Washington, March 2003.
[UTF-8] Yergeau, F., "UTF-8, a transformation format of IS0 10646",
RFC 3629, Alis Technologies, November 2003.
[Stringprep] Hoffman, P., Blanchet, M., "Preparation of
Internationalized Strings ("stringprep")", RFC 3454, December 2002.
[SASLprep] Zeilenga, K., "SASLprep: Stringprep profile for User Names
and Passwords", RFC 4013, February 2005.
11.2. Informative References
[RFC2086] Myers, J., "IMAP4 ACL extension", RFC 2086, Carnegie Mellon,
January 1997.
12. Editor's Address
Alexey Melnikov
email: alexey.melnikov@isode.com
Isode Limited
13. IPR Disclosure Acknowledgement
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.
14. 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.
15. Full 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.
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.
Acknowledgement
Funding for the RFC Editor function is currently provided by the Section 3 states requirements on servers regarding
Internet Society. internationalization of identifiers.
Appendix A. Changes since RFC 2086 Appendix A. Changes since RFC 2086
1. Changed the charset of "identifier" from US-ASCII to UTF-8. 1. Changed the charset of "identifier" from US-ASCII to UTF-8.
2. Specified that mailbox deletion is controled by the "x" right
2. Specified that mailbox deletion is controled by the "x" right and and EXPUNGE is controlled by the "e" right.
EXPUNGE is controlled by the "e" right. 3. Added the "t" right that controls STORE \Deleted. Redefined the
"d" right to be a macro for "e", "t" and possibly "x".
3. Added the "t" right that controls STORE \Deleted. Redefined the "d"
right to be a macro for "e", "t" and possibly "x".
4. Added the "k" right that controls CREATE. Redefined the "c" 4. Added the "k" right that controls CREATE. Redefined the "c"
right to be a macro for "k" and possibly "x". right to be a macro for "k" and possibly "x".
5. Specified that the "a" right also controls DELETEACL. 5. Specified that the "a" right also controls DELETEACL.
6. Specified that the "r" right also controls STATUS. 6. Specified that the "r" right also controls STATUS.
7. Removed the requirement to check the "r" right for CHECK, SEARCH
7. Removed the requirement to check the "r" right for CHECK, SEARCH and and FETCH, as this is required for SELECT/EXAMINE to be
FETCH, as this is required for SELECT/EXAMINE to be successful. successful.
8. LISTRIGHTS requires the "a" right on the mailbox (same as
8. LISTRIGHTS requires the "a" right on the mailbox (same as SETACL). SETACL).
9. Deleted "PARTIAL", this is a deprecated feature of RFC 1730. 9. Deleted "PARTIAL", this is a deprecated feature of RFC 1730.
10. Specified that the "w" right controls setting flags other than
10. Specified that the "w" right controls setting flags other than \Seen \Seen and \Deleted on APPEND. Also specified that the "s" right
and \Deleted on APPEND. Also specified that the "s" right controls controls the \Seen flag and that the "t" right controls the
the \Seen flag and that the "t" right controls the \Deleted flag. \Deleted flag.
11. Specified that SUBSCRIBE is NOT allowed with the "r" right. 11. Specified that SUBSCRIBE is NOT allowed with the "r" right.
12. Specified that the "l" right controls SUBSCRIBE. 12. Specified that the "l" right controls SUBSCRIBE.
13. GETACL is NOT allowed with the "r" right, even though there are 13. GETACL is NOT allowed with the "r" right, even though there are
several implementations that allows that. If a user only has "r" several implementations that allows that. If a user only has
right, GETACL can disclose information about identifiers existing "r" right, GETACL can disclose information about identifiers
on the mail system. existing on the mail system.
14. Clarified that RENAME requires the "k" right for the new parent
14. Clarified that RENAME requires the "k" right for the new parent and and the "x" right for the old name.
the "x" right for the old name. 15. Added new section that describes which rights are required
and/or checked when performing various IMAP commands.
15. Added new section that describes which rights are required and/or
checked when performing various IMAP commands.
16. Added mail client security considerations when dealing with special
identifier "anyone".
16. Added mail client security considerations when dealing with
special identifier "anyone".
17. Clarified that negative rights are not the same as DELETEACL. 17. Clarified that negative rights are not the same as DELETEACL.
18. Added "Compatibility with RFC 2086" section. 18. Added "Compatibility with RFC 2086" section.
19. Added section about mapping of ACL rights to READ-WRITE and
19. Added section about mapping of ACL rights to READ-WRITE and READ-ONLY READ-ONLY response codes.
response codes.
20. Changed BNF to ABNF. 20. Changed BNF to ABNF.
21. Added "Implementation Notes" section. 21. Added "Implementation Notes" section.
22. Updated "References" section. 22. Updated "References" section.
23. Added more examples. 23. Added more examples.
24. Clarified when the virtual "c" and "d" rights are returned in
24. Clarified when the virtual "c" and "d" rights are returned in ACL, ACL, MYRIGHTS and LISTRIGHTS responses.
MYRIGHTS and LISTRIGHTS responses.
Appendix B. Compatibility with RFC 2086 Appendix B. Compatibility with RFC 2086
This non-normative section gives guidelines how an existing RFC 2086 This non-normative section gives guidelines how an existing RFC 2086
server implementation may be updated to comply with this document. server implementation may be updated to comply with this document.
This document splits the "d" right into several new different rights: This document splits the "d" right into several new different rights:
"t", "e" and possibly "x" (see section 3.1.1 for more details). The "d" "t", "e" and possibly "x" (see Section 2.1.1 for more details). The
right remains for backwards-compatibility but it is a virtual right. "d" right remains for backwards-compatibility but it is a virtual
There are two approaches for RFC2086 server implementors to right. There are two approaches for RFC2086 server implementors to
handle the "d" right and the new rights that have replaced it. handle the "d" right and the new rights that have replaced it:
a). "t", "e" (and possibly "x) together - almost no changes. a. "t", "e" (and possibly "x) together - almost no changes.
b). Implement separate "x", "t" and "e". Return the "d" right in a b. Implement separate "x", "t" and "e". Return the "d" right in a
MYRIGHTS response or an ACL response containing ACL MYRIGHTS response or an ACL response containing ACL information
information when any of the "t", "e" (and "x") is granted. when any of the "t", "e" (and "x") is granted.
In a similar manner this document splits the "c" right into several In a similar manner this document splits the "c" right into several
new different rights: "k" and possibly "x" (see section 3.1.1 for more new different rights: "k" and possibly "x" (see Section 2.1.1 for
details). The "c" right remains for backwards-compatibility but it is more details). The "c" right remains for backwards-compatibility but
a virtual right. Again, RFC2086 server implementors can choose it is a virtual right. Again, RFC2086 server implementors can choose
to tie rights or to implement separate rights, as described above. to tie rights or to implement separate rights, as described above.
Also check Sections 6.1 and 6.2, as well as the appendix A to see Also check Sections Section 5.1.1 and Section 5.1.2, as well as the
other changes required. Server implementors should check which rights Appendix A to see other changes required. Server implementors should
are required to invoke different IMAP4 commands as described in check which rights are required to invoke different IMAP4 commands as
Section 5. described in Section 4.
Appendix C. Known deficiencies Appendix C. Known deficiencies
This specification has some known deficiencies including: This specification has some known deficiencies including:
1. This is inadequate to provide complete read-write access to 1. This is inadequate to provide complete read-write access to
mailboxes protected by Unix-style rights bits because there is no mailboxes protected by Unix-style rights bits because there is no
equivalent to "chown" and "chgrp" commands nor is there a good way equivalent to "chown" and "chgrp" commands nor is there a good
to discover such limitations are present. way to discover such limitations are present.
2. Because this extension leaves the specific semantics of how rights
are combined by the server as implementation defined, the ability
to build a user-friendly interface is limited.
2. Because this extension leaves the specific semantics of how
rights are combined by the server as implementation defined, the
ability to build a user-friendly interface is limited.
3. Users, groups, and special identifiers (e.g. anyone) exist in the 3. Users, groups, and special identifiers (e.g. anyone) exist in the
same namespace. same namespace.
The work-in-progress "ACL2" extension is intended to redesign this The work-in-progress "ACL2" extension is intended to redesign this
extension to address these deficiencies without the constraint of extension to address these deficiencies without the constraint of
backwards-compatibility and may eventually supercede this facility. backwards-compatibility and may eventually supercede this facility.
However, RFC 2086 is deployed in multiple implementations so this However, RFC 2086 is deployed in multiple implementations so this
intermediate step which fixes the straightforward deficiencies in a intermediate step which fixes the straightforward deficiencies in a
backwards compatible fashion is considered worthwhile. backwards compatible fashion is considered worthwhile.
Appendix D. Acknowledgment Appendix D. Acknowledgments
This document is a revision of the RFC 2086 written by John G. Myers. This document is a revision of the RFC 2086 written by John G. Myers.
Editor appreciates comments received from Mark Crispin, Chris Newman, Editor appreciates comments received from Mark Crispin, Chris Newman,
Cyrus Daboo, John G. Myers, Dave Cridland, Ken Murchison, Steve Hole, Cyrus Daboo, John G. Myers, Dave Cridland, Ken Murchison, Steve Hole,
Vladimir Butenko, Larry Greenfield, Robert Siemborski, Harrie Vladimir Butenko, Larry Greenfield, Robert Siemborski, Harrie
Hazewinkel, Philip Guenther, Brian Candler, Curtis King, Lyndon Hazewinkel, Philip Guenther, Brian Candler, Curtis King, Lyndon
Nerenberg, Lisa Dusseault, Arnt Gulbrandsen and other participants Nerenberg, Lisa Dusseault, Arnt Gulbrandsen and other participants of
of the IMAPEXT working group. the IMAPEXT working group.
10. References
10.1 Normative References
[KEYWORDS]
Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[ABNF] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 2234, November 1997.
[IMAP4] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION
4rev1", RFC 3501, March 2003.
[UTF-8] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, November 2003.
[Stringprep]
Hoffman, P. and M. Blanchet, "Preparation of
Internationalized Strings ("stringprep")", RFC 3454,
December 2002.
[SASLprep]
Zeilenga, K., "SASLprep: Stringprep Profile for User Names
and Passwords", RFC 4013, February 2005.
10.2 Informative References
[RFC2086] Myers, J., "IMAP4 ACL extension", RFC 2086, January 1997.
Author's Address
Alexey Melnikov
Isode Ltd.
5 Castle Business Village
36 Station Road
Hampton, Middlesex TW12 2BX
GB
Email: alexey.melnikov@isode.com
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
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The IETF invites any interested party to bring to its attention any
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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.
The IETF has been notified of intellectual property rights claimed in
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Copyright (C) The Internet Society (2005). This document is subject
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Funding for the RFC Editor function is currently provided by the
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 End of changes. 

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