Allowing Inheritable NFSv4 Access Control Entries to Override the Umask
draft-ietf-nfsv4-umask-04

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NFSv4                                                          J. Fields
Internet-Draft                                            A. Gruenbacher
Intended status: Standards Track                                 Red Hat
Expires: January 21, 2018                                  July 20, 2017

Allowing Inheritable NFSv4 Access Control Entries to Override the Umask
                       draft-ietf-nfsv4-umask-04

Abstract

   In many environments, inheritable NFSv4 Access Control Entries (ACEs)
   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 January 21, 2018.

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
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
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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  . . . . . . . . . . . . . . . . .   5
   Appendix A.  Acknowledgments  . . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   5

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 Access Control List (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 ACL
   entries (inheritable ACEs) describing the permissions to be granted
   to named users and groups are often ignored.  This makes inheritable
   ACEs useless in some common cases.

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   Linux solves this problem on local filesystems by ignoring the umask
   in the case the parent of the newly-created file has inheritable