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Revision as of 12:20, 9 January 2023 by Ipedrosa (talk | contribs)

Remove pam_console

This is a proposed Change for Fedora Linux.
This document represents a proposed Change. As part of the Changes process, proposals are publicly announced in order to receive community feedback. This proposal will only be implemented if approved by the Fedora Engineering Steering Committee.

Summary

Remove pam_console as it does nothing.

Owner


Current status

  • Targeted release: Fedora Linux 39
  • Last updated: 2023-01-09
  • FESCo issue: <will be assigned by the Wrangler>
  • Tracker bug: <will be assigned by the Wrangler>
  • Release notes tracker: <will be assigned by the Wrangler>

Detailed Description

pam_console give users at the physical console additional capabilities when authenticating, and removes those capabilities when the user logs out. The module changes the permissions and ownership of files and devices.

pam_console has some limitations and flaws, including several security concerns. If the user isn't logged out successfully, the permissions wouldn't be retired. Moreover, there are some scenarios in which an inactive session could spy on active sessions. Besides, only one user can have those additional capabilities at the same time, as the module isn't multi-seat compliant. Finally,, the module does nothing because one of the configuration files (50-default.perms) is not installed in the distribution. This file is used to define the permissions, and as it isn't installed there isn't any permission defined.

Other packages may install their own configuration files to specify the permissions, but I haven't found any.

These additional capabilities that pam_console provides are useful to simplify the work for console users. Usually, the permissions are set for devices like the CD/DVD reader, or the disk drives. This functionality is still useful today, and it should be managed with systemd-logind, rather than with a PAM module. This systemd service takes care of user sessions, multi-seat management, device access management... This would increase the security level of the system, and enable multi-seat for the file and device permissions.

In 2007 there was a System-Wide Change proposal to remove pam_console, but it wasn't finished. My plan is to continue that work and remove the pam_console module.


Feedback

Benefit to Fedora

The main benefit is that it reduces the maintenance effort of the package, without reducing the functionality. The pam_console module is not included in the Linux-PAM, and it has to be maintained in a side-project. On top of that, the module is only used in Fedora and some of its derivatives.

Scope

  • Proposal owners:
  1. Provide PRs to remove pam_console from the PAM stack of the identified software packages (see Dependencies).
  2. Remove pam_console from pam-redhat project and rebuild the PAM package without it.
  • Other developers:
  1. Identified software package maintainers should review and merge the pam_console removal PRs.
  • Policies and guidelines: N/A
  • Trademark approval: N/A
  • Alignment with Objectives: N/A

Upgrade/compatibility impact

No impact is expected.


How To Test

No special hardware or configuration is required to test this change. Once the change is in place, check that the pam_console isn't installed in your system (default location: /lib64/security/pam_console.so) and do a user authentication (i.e. graphical interface, su, ssh, and whatever else comes to your mind).


User Experience

Users won't experience any change.

Dependencies

This change depends on other packages removing pam_console from their PAM stack. I have identified five packages and I have opened a bugzilla for all of them:

From the above list only the first item is a blocker as it requires pam_console to succeed in the authentication. In all other cases it is optional, so not removing the module from their PAM stack will only cause a message printed in the security file.


Contingency Plan

  • Contingency mechanism: Postpone to the next release.
  • Contingency deadline: Beta freeze.
  • Blocks release? No.


Documentation

No documentation.


Release Notes

No need to update the release notes for this change.

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