Bug 2096191

Summary:	glibc: Backport no-aaaa resolver option to suppress DNS AAAA queries [rhel-9.1.0]
Product:	Red Hat Enterprise Linux 9	Reporter:	Florian Weimer <fweimer>
Component:	glibc	Assignee:	glibc team <glibc-bugzilla>
Status:	CLOSED ERRATA	QA Contact:	Sergey Kolosov <skolosov>
Severity:	unspecified	Docs Contact:	Petr Hybl <phybl>
Priority:	unspecified
Version:	9.1	CC:	allen.payne, arawal, ashankar, byodlows, codonell, dj, fadamo, fweimer, glibc-bugzilla, jfont, mnewsome, pfrankli, phybl, qe-baseos-tools-bugs, sipoyare
Target Milestone:	rc	Keywords:	FutureFeature, Triaged
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:	glibc-2.34-39.el9	Doc Type:	Enhancement
Doc Text:	.DNS stub resolver option now supports `no-aaaa` option With this enhancement, `glibc` now recognizes the `no-aaaa` stub resolver option in `/etc/resolv.conf` and the `RES_OPTIONS` environment variable. When this option is active, no AAAA queries will be sent over the network. System administrators can disable AAAA DNS lookups for diagnostic purposes, such as ruling out that the superfluous lookups on IPv4-only networks do not contribute to DNS issues.	Story Points:	---
Clone Of:	2096189	Environment:
Last Closed:	2022-11-15 11:11:50 UTC	Type:	Enhancement
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	2096189

Description Florian Weimer 2022-06-13 08:50:02 UTC

This change needs to be forwarded-ported to Red Hat Enterprise Linux 9.1 to avoid a feature regression.

+++ This bug was initially created as a clone of Bug #2096189 +++

We are working upstream on a no-aaaa stub resolver option that suppresses DNS AAAA queries for diagnostic purposes.

Upstream NEWS entry:

+* The “no-aaaa” DNS stub resolver option has been added.  System
+  administrators can use it to suppress AAAA queries made by the stub
+  resolver, including AAAA lookups triggered by NSS-based interfaces
+  such as getaddrinfo.  Only DNS lookups are affected: IPv6 data in
+  /etc/hosts is still used, getaddrinfo with AI_PASSIVE will still
+  produce IPv6 addresses, and configured IPv6 name servers are still
+  used.  To produce correct Name Error (NXDOMAIN) results, AAAA queries
+  are translated to A queries.  The new resolver option is intended
+  preliminary for diagnostic purposes, to rule out that AAAA DNS queries
+  have adverse impact.  It is incompatible with EDNS0 usage and DNSSEC
+  validation by applications.

Patch:

[PATCH v2 2/2] resolv: Implement no-aaaa stub resolver option
https://sourceware.org/pipermail/libc-alpha/2022-June/139549.html

The proposed patch does not directly affect AF_UNSPEC queries, so it is distinct from bug 1027452, which is why I'm filing a separate bug.

Note to QE: Various “getent” queries (hosts, ahosts, ahostsv4, ahostsv6) for hosts in DNS are expected not to show any AAAA queries in tcpdump if the no-aaaa option is active.

Comment 10 errata-xmlrpc 2022-11-15 11:11:50 UTC

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (glibc bug fix and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2022:8272

Comment 13 Florian Weimer 2022-11-21 11:11:03 UTC

NetworkManager integration is currently missing. If NetworkManager is used to manage /etc/resolv.conf, changes to this file will be overwritten. NetworkManager does not propagate no-aaaa from the interface DNS configuration even if it set there.