From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lists.gentoo.org (pigeon.gentoo.org [208.92.234.80]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by finch.gentoo.org (Postfix) with ESMTPS id CCA8F138334 for ; Wed, 5 Jun 2019 09:18:50 +0000 (UTC) Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 6FD72E09DA; Wed, 5 Jun 2019 09:18:47 +0000 (UTC) Received: from smtp.gentoo.org (smtp.gentoo.org [140.211.166.183]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by pigeon.gentoo.org (Postfix) with ESMTPS id 0E2C1E0963 for ; Wed, 5 Jun 2019 09:18:46 +0000 (UTC) Received: from localhost.localdomain (d202-252.icpnet.pl [109.173.202.252]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: mgorny) by smtp.gentoo.org (Postfix) with ESMTPSA id 382F7345743; Wed, 5 Jun 2019 09:18:45 +0000 (UTC) From: =?UTF-8?q?Micha=C5=82=20G=C3=B3rny?= To: gentoo-dev@lists.gentoo.org Cc: =?UTF-8?q?Micha=C5=82=20G=C3=B3rny?= Subject: [gentoo-dev] [PATCH v2] glep-xxxx: User and group management via dedicated packages Date: Wed, 5 Jun 2019 11:18:39 +0200 Message-Id: <20190605091839.17396-1-mgorny@gentoo.org> X-Mailer: git-send-email 2.22.0.rc3 Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-dev@lists.gentoo.org Reply-to: gentoo-dev@lists.gentoo.org X-Auto-Response-Suppress: DR, RN, NRN, OOF, AutoReply MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Archives-Salt: 56099d1d-3b3f-4f18-b656-31dc794c7eb8 X-Archives-Hash: a3e94f10441bba9800b93b7cc90ded97 Here's the updated GLEP text. It has a few small changes based on feedback, and links reference implementation submitted to the ml. Signed-off-by: Michał Górny --- glep-9999.rst | 233 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 233 insertions(+) create mode 100644 glep-9999.rst diff --git a/glep-9999.rst b/glep-9999.rst new file mode 100644 index 0000000..19555a6 --- /dev/null +++ b/glep-9999.rst @@ -0,0 +1,233 @@ +--- +GLEP: 9999 +Title: User and group management via dedicated packages +Author: Michał Górny , + Michael Orlitzky +Type: Standards Track +Status: Draft +Version: 1 +Created: 2019-05-29 +Last-Modified: 2019-06-05 +Post-History: 2019-05-29 +Content-Type: text/x-rst +Requires: +Replaces: 27 +--- + +Abstract +======== + +A new approach for user/group management is proposed. Regular packages +in dedicated categories are used to represent and create user and group +accounts. Dependencies are used to request users and group from within +regular packages, and to track their usage. + + +Motivation +========== + +User management in Gentoo is currently ad-hoc. Users and groups are +created through calling system tools directly in packages needing them. +There is no systematic way of tracking which packages need specific +users or groups, and determining which ones are obsolete. Coordinating +properties of users and groups used by multiple packages must be done +manually by developers. + +GLEP 27 originally attempted to address the problem. Posted in 2004, +it never had reached the reference implementation state, and became +obsolete. [#GLEP27]_ + +A good system user and group management proposal should address: + +1. Tracking usage of users and groups, and determining which ones + are obsolete. + +2. Sharing users and groups reliably between different packages. + +3. Maintaining fixed UIDs/GIDs that are consistent between different + systems. + +4. Providing local overrides for user/group properties. + +5. Ensuring that users and groups are not created unnecessarily + at build time. + +6. Providing support for centralized account management (e.g. LDAP). + +At the same time, the proposal should avoid unnecessary complexity +to avoid sharing the fate of GLEP 27. This proposal aims to address +those points without requiring a new EAPI or any changes in the package +manager. + + +Specification +============= + +Logical structure +----------------- + +In this proposal, system users and groups are represented by regular +packages. Those packages logically represent the ownership of +the respective users and group, and technically implement their +creation. + +User packages are placed in ``acct-user`` category. Each user package +defines the properties of the particular user, and must be named after +the user it creates. It must depend at build and run time on the groups +the user belongs to. + +Group packages are placed in ``acct-group`` category. Each group +package defines the properties of the particular group, and must be +named after the group it creates. + +All user and group packages must define preferred fixed UIDs/GIDs, +and they must be unique within the repository. The packages should +indicate whether the value needs to be strictly enforced, or whether +another UID/GID can be used when the user exists already or requested +UID/GID is taken. + +Packages needing a specific user or group use dependencies to pull +the required user/group packages. If the user is needed at build time, +a build time dependency (``DEPEND``) must be used. If the user is +needed at install time, a run time dependency (``RDEPEND``) must be +used. If the user is only needed after the package is installed, +``PDEPEND`` must be used. + + +Maintaining users/groups +------------------------ + +The primary technical function of user and group packages is to create +the users and groups. This is done via invoking the respective system +tools at ``pkg_preinst`` phase. This is done only if the user/group +does not exist on the system already. + +Normally, the packages should not modify existing users, in order not +to overwrite local modifications. If an explicit update is necessary, +the package should compare the existing values against expected previous +properties, and update them only if they were not changed. + +The package must not remove users/groups. When the account is no longer +needed, the tooling must ensure that it is locked from access. However, +any cleanup actions must be done with explicit user approval, +and therefore should be addressed by separate tooling. + + +Home directory ownership +------------------------ + +If the user in question uses a regular home directory (i.e. not +``/dev/null``), the user package should maintain the directory +via ``keepdir`` command. This allows for clean removal of the home +directory if it is no longer needed. The package manager will also +apply correct permissions if the directory does not exist yet. + +Note that since the user is not created until ``pkg_preinst``, +the permissions to home directory should not be applied earlier than +that. + + +Rationale +========= + +Satisfied goals +--------------- + +Tracking of user/group usage is done through dependencies. As long +as any installed package depends on a specific user/group package, +the respective user/group is assumed to be used. If no package +requiring the specific user/group is left, the package manager +automatically prunes the package clearly indicating it is no longer +used. + +Each user and group has a single respective package creating it. +If multiple packages need it, they depend on the same package. This +ensures that all properties are kept in a single location, and do not +need to be synced. + +Having a single location with all predefined user/group ranges makes it +possible to maintain fixed UID/GID definitions. This GLEP makes +allocating them obligatory. While this isn't enforced for existing +users, it provides a way forward for new installations. + +Local overrides can be trivially implemented via local repository, +through overriding the respective user/group ebuilds. The proposal also +respects direct sysadmin modifications. + +Avoiding unnecessary user/group creation at build time is implemented +via correct dependency types. While this was possible with the status +quo, the dependency model should be more natural to developers and cause +less mistakes. + + +Category names +-------------- + +The original proposal used ``sys-user`` and ``sys-group`` as category +names. This was changed in order to avoid mixing them with regular +packages in ``sys-*`` categories. + +The new names intentionally are single component to distinguish them +from regular packages. + + +User/group updates +------------------ + +If sysadmin needs to change the properties (e.g. home directory) of some +user/group, the obvious course of action is to modify the system +databases directly. The GLEP aims to respect that and disallow altering +existing user/groups without explicit user request. If any updates need +to be done, the packages need to verify previous values first. + + +User/group removal +------------------ + +The original proposal attempted to remove user/groups automatically +when the respective package was unmerged. This required verifying that +no files are owned by the user/group in question which was both +expensive in terms of I/O, and fragile. + +This GLEP follows the best practice of leaving obsolete user/groups +accounts while ensuring that they are locked out properly. This +guarantees that no files with stale ownership are left +e.g. on unmounted filesystems) and that the same UID/GID is not reused +for another user/group. + + +Backwards Compatibility +======================= + +This GLEP preserves backwards compatibility with the existing method +of user/group management. Both methods can coexist as long as necessary +for the transition period, and the same user/group can be governed +by both in parallel. + +However, some of the advantages will only be reliable once the old +method is phased out, and only on new installations. This particularly +applies to fixed UIDs/GIDs. + + +Reference Implementation +======================== + +The reference implementation has been submitted to review on gentoo-dev +mailing list. The version at the time of writing is v2. [#REFIMPL]_ + + +References +========== + +.. [#GLEP27] GLEP 27: Portage Management of UIDs/GIDs + (https://www.gentoo.org/glep/glep-0027.html) + +.. [#REFIMPL] [gentoo-dev] [PATCH v2 0/9] User/group packages + (https://archives.gentoo.org/gentoo-dev/message/ccc85af0511f70ee9d3549b89bd8a40b) + + +Copyright +========= +This work is licensed under the Creative Commons Attribution-ShareAlike 3.0 +Unported License. To view a copy of this license, visit +http://creativecommons.org/licenses/by-sa/3.0/. -- 2.22.0.rc3