Package: debian-policy
Version: 4.7.4.1
Severity: normal

DNSSEC-enabled DNS resolvers must depend on the dns-root-data package 
instead of shipping built-in trust anchors.
The dns-root-data is a trivial, arch:all package whose only purpose is 
to provide a current DNS root zone and DNSSEC trust anchors, even for 
end of support Debian releases.

Short summary for people who are not familiar with DNSSEC: domains 
resolution will stop working if the trust anchors are not up to date.
There is a mechanism (RFC 5011) to update them automatically in band, 
but it requires that the resolver was working *before* the rollover.

Due to complex reasons (pandemic, end of life HSMs...) only three root 
zone KSKs have been deployed so far[1] since 2010, the most recent one 
last Sunday, but the current IANA plan[1] is to rotate the root KSK 
every 3 years.  This means that this failure will be much more frequent 
in the future.

Most important DNS resolvers already depend on dns-root-data: bind9, 
pdns-recursor, knot-resolver6.
Some important DNS resolvers only recommend dns-root-data: unbound, 
dnsmasq-base.
Only one important DNS resolver does not use dns-root-data (but AFAICT 
could with just a symlink): systemd-resolved.

Embarrassing failures:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1150730
https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/2170538

[1] https://www.iana.org/dnssec/files
[2] 
https://www.icann.org/en/system/files/files/proposal-future-rz-ksk-rollovers-01nov19-en.pdf

-- 
ciao,
Marco

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