Allowing Inheritable NFSv4 ACLs to Override the Umask
draft-ietf-nfsv4-umask-03

Document Type Active Internet-Draft (nfsv4 WG)
Last updated 2017-03-03
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NFSv4                                                          J. Fields
Internet-Draft                                            A. Gruenbacher
Intended status: Standards Track                                 Red Hat
Expires: September 4, 2017                                March 03, 2017

         Allowing Inheritable NFSv4 ACLs to Override the Umask
                       draft-ietf-nfsv4-umask-03

Abstract

   In many important environments, inheritable NFSv4 ACLs can be
   rendered ineffective by the application of the per-process umask.
   This can be addressed by transmitting the umask and create mode as
   separate pieces of data, allowing the server to make more intelligent
   decisions about the permissions to set on new files.  This document
   proposes a protocol extension which accomplishes that.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on September 4, 2017.

Copyright Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   include Simplified BSD License text as described in Section 4.e of

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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Conventions Used in This Document . . . . . . . . . . . . . .   2
   2.  Problem Statement . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Protocol Extension Considerations . . . . . . . . . . . . . .   3
   4.  mode_umask Attribute  . . . . . . . . . . . . . . . . . . . .   3
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Appendix A.  Acknowledgments  . . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Conventions Used in This Document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

2.  Problem Statement

   On Unix-like systems, each process is associated with a file mode
   creation mask (umask), which specifies which permissions must be
   turned off when creating new file system objects.

   When applying the mode, section 6.4.1.1 of [RFC7530] recommends that
   servers SHOULD restrict permissions granted to any user or group
   named in the ACL to be no more than the permissions granted by the
   MODE4_RGRP, MODE4_WGRP, and MODE4_XGRP bits.  Servers aiming to
   provide clients with Unix-like chmod behavior may also be motivated
   by the same requirements in [SUSv4].  (See the discussion of
   additional and alternate access control mechanisms in section "4.4
   File Permissions" of that document.)

   On many existing installations, all ordinary users by default use the
   same effective group ID.  To prevent granting all users full access
   to each other's files, such installations usually default to a umask
   with very restrictive permissions.  As a result, inherited ACEs
   describing the permissions to be granted to named users and groups
   are often ignored.  This makes inheritable ACLs useless in some
   common cases.

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