[Bug 1897744] Re: VerifyHostKeyDNS not working due to missing trust-ad flag

[Brian Murray]

Hello Daniel, or anyone else affected,

Accepted systemd into focal-proposed. The package will build now and be
available at
https://launchpad.net/ubuntu/+source/systemd/245.4-4ubuntu3.3 in a few
hours, and then in the -proposed repository.

Please help us by testing this new package.  See
https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how
to enable and use -proposed.  Your feedback will aid us getting this
update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug,
mentioning the version of the package you tested, what testing has been
performed on the package and change the tag from verification-needed-
focal to verification-done-focal. If it does not fix the bug for you,
please add a comment stating that, and change the tag to verification-
failed-focal. In either case, without details of your testing we will
not be able to proceed.

Further information regarding the verification process can be found at
https://wiki.ubuntu.com/QATeam/PerformingSRUVerification .  Thank you in
advance for helping!

N.B. The updated package will be released to -updates after the bug(s)
fixed by this package have been verified and the package has been in
-proposed for a minimum of 7 days.

** Changed in: systemd (Ubuntu Focal)
       Status: In Progress => Fix Committed

** Tags added: verification-needed verification-needed-focal

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https://bugs.launchpad.net/bugs/1897744

Title:
  VerifyHostKeyDNS not working due to missing trust-ad flag

Status in systemd package in Ubuntu:
  Fix Released
Status in systemd source package in Focal:
  Fix Committed

Bug description:
  [impact]

  without trust-ad resolv.conf option, glibc will strip AD from systemd-
  resolved responses. one thing this will prevent working is ssh
  VerifyHostKeyDNS

  [test case]

  see
  https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1898590/comments/7

  [regression potential]

  regressions would likely involve DNS lookup failures, probably if
  DNSSEC is enabled but possibly even without, and likely when the
  application requesting the dns lookup processes the response AD.

  [scope]

  this is needed only in focal.

  glibc first stripped the AD in version 2.31, so this is not needed in
  bionic or earlier.

  this was added upstream in commit a742f9828ea which was included in
  v246, so this is fixed already in groovy.

  [original description]

  Hi,

  1)
  Description:	Ubuntu 20.04.1 LTS
  Release:	20.04

  2)
  systemd:        245.4-4ubuntu3.2

  3)
  I set VerifyHostKeyDNS to YES and hosts are automatically verified via sshfp.

  4)
  I still get the security question
  Matching host key fingerprint found in DNS.
  Are you sure you want to continue connecting (yes/no/[fingerprint])?

  The issue is known and fixed in systemd v246.
  https://github.com/systemd/systemd/pull/16072

  Best regards
  Daniel

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