Bug 1898327 - Use of undocumented option in system resolver
Summary: Use of undocumented option in system resolver
Keywords:
Status: CLOSED NEXTRELEASE
Alias: None
Product: Fedora
Classification: Fedora
Component: man-pages
Version: 33
Hardware: Unspecified
OS: Unspecified
unspecified
unspecified
Target Milestone: ---
Assignee: Nikola Forró
QA Contact: Fedora Extras Quality Assurance
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2020-11-16 20:16 UTC by Brian 'redbeard' Harrington
Modified: 2021-11-05 07:22 UTC (History)
13 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed: 2021-11-05 07:22:04 UTC
Type: Bug
Embargoed:


Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Bugzilla 1164339 0 unspecified CLOSED dnssec: glibc: don't blindly trust the AD flag from nameservers in /etc/resolv.conf 2021-02-22 00:41:40 UTC

Description Brian 'redbeard' Harrington 2020-11-16 20:16:49 UTC
Description of problem:
In version 2.31 of GLIBC the option "trust-ad" was added and is now being set on new installations.  On a default fedora 33 installation, this is the contents of /etc/resolv.conf:


[~]$ cat /etc/resolv.conf 
# This file is managed by man:systemd-resolved(8). Do not edit.
#
# This is a dynamic resolv.conf file for connecting local clients to the
# internal DNS stub resolver of systemd-resolved. This file lists all
# configured search domains.
#
# Run "resolvectl status" to see details about the uplink DNS servers
# currently in use.
#
# Third party programs should typically not access this file directly, but only
# through the symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a
# different way, replace this symlink by a static file or a different symlink.
#
# See man:systemd-resolved.service(8) for details about the supported modes of
# operation for /etc/resolv.conf.

nameserver 127.0.0.53
options edns0 trust-ad


Unfortunately there is no reference to this in man 5 resolv.conf (nor in man 3 resolver, though this appears to be missing upstream as well in the change set - https://gnutoolchain-gerrit.osci.io/r/c/glibc/+/461).

The updated man page can be referenced on Michael Kerrisk's site: https://www.man7.org/linux/man-pages/man5/resolv.conf.5.html


The lack of this information presents a challenge to users auditing behavioral changes between different hosts running Fedora.



Version-Release number of selected component (if applicable):

[~]$ rpm -q glibc
glibc-2.32-1.fc33.x86_64
[~]$ cat /etc/os-release 
NAME=Fedora
VERSION="33 (Workstation Edition)"
ID=fedora
VERSION_ID=33
VERSION_CODENAME=""
PLATFORM_ID="platform:f33"
PRETTY_NAME="Fedora 33 (Workstation Edition)"
ANSI_COLOR="0;38;2;60;110;180"
LOGO=fedora-logo-icon
CPE_NAME="cpe:/o:fedoraproject:fedora:33"
HOME_URL="https://fedoraproject.org/"
DOCUMENTATION_URL="https://docs.fedoraproject.org/en-US/fedora/f33/system-administrators-guide/"
SUPPORT_URL="https://fedoraproject.org/wiki/Communicating_and_getting_help"
BUG_REPORT_URL="https://bugzilla.redhat.com/"
REDHAT_BUGZILLA_PRODUCT="Fedora"
REDHAT_BUGZILLA_PRODUCT_VERSION=33
REDHAT_SUPPORT_PRODUCT="Fedora"
REDHAT_SUPPORT_PRODUCT_VERSION=33
PRIVACY_POLICY_URL="https://fedoraproject.org/wiki/Legal:PrivacyPolicy"
VARIANT="Workstation Edition"
VARIANT_ID=workstation

Comment 1 Florian Weimer 2020-11-16 20:47:35 UTC
I submitted a patch to the man-pages project:

https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/commit/?id=a3f91ca97b6fe81da1598e4c3c3af9ed199d1338

It's not been long ago, so it's probably not yet in Fedora.

Comment 2 Ben Cotton 2021-11-04 17:14:50 UTC
This message is a reminder that Fedora 33 is nearing its end of life.
Fedora will stop maintaining and issuing updates for Fedora 33 on 2021-11-30.
It is Fedora's policy to close all bug reports from releases that are no longer
maintained. At that time this bug will be closed as EOL if it remains open with a
Fedora 'version' of '33'.

Package Maintainer: If you wish for this bug to remain open because you
plan to fix it in a currently maintained version, simply change the 'version' 
to a later Fedora version.

Thank you for reporting this issue and we are sorry that we were not 
able to fix it before Fedora 33 is end of life. If you would still like 
to see this bug fixed and are able to reproduce it against a later version 
of Fedora, you are encouraged  change the 'version' to a later Fedora 
version prior this bug is closed as described in the policy above.

Although we aim to fix as many bugs as possible during every release's 
lifetime, sometimes those efforts are overtaken by events. Often a 
more recent Fedora release includes newer upstream software that fixes 
bugs or makes them obsolete.

Comment 3 Nikola Forró 2021-11-05 07:22:04 UTC
This is fixed since man-pages 5.10, in Fedora 34 and up.


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