Multicast traffic is broken between VMs on different hypervisors using provider networks

[James Troup]

[Impact]
In an OpenStack Ussuri (both Focal and Bionic) cloud we discovered that multicast traffic would fail between VMs on different hypervisors and when using provider networks.

[Test Plan]
The upstream fix also contains an addition to the OVN testsuite confirming the correct behavior. We cat utilize this test case to perform both a control test on a unmodified package as well as confirming that a updated package fixes the problem.

[Regression Potential]
The fix touches a code path that is executed only when OVN is configured to enable handling of Multicast traffic. The fix has also been available for several upstream releases without any reported issues.

[Original Bug Description]
In an OpenStack Ussuri (both Focal and Bionic) cloud we discovered that multicast traffic would fail between VMs on different hypervisors and when using provider networks. The following table reflects what we found works/didn't work:

 https://paste.ubuntu.com/p/QZZBjrTSFQ/

Based on this, I went looking at relevant changes upstream and found that this appears to have been fixed upstream, but not backported to OVN 20.03:

https://github.com/ovn-org/ovn/commit/97778ab3e422ac071faa67f9f477fd54977e9c04

I backported this patch to the version of OVN in Ussuri here:

  https://launchpad.net/~elmo/+archive/ubuntu/sf322809

These patched packages have been tested on a customer site and confirmed to fix the problem.

I've attached the patch from the PPA for convenience.

[Ubuntu Foundations Team Bug Bot (crichton)]

The attachment "Backport of 97778ab3e422ac071faa67f9f477fd54977e9c04 to OVN 20.03.2" seems to be a patch. If it isn't, please remove the "patch" flag from the attachment, remove the "patch" tag, and if you are a member of the ~ubuntu-reviewers, unsubscribe the team.

[This is an automated message performed by a Launchpad user owned by ~brian-murray, for any issues please contact him.]

[James Page (james-page)]

@fnordahl I've merged and will uploaded for SRU team review however we still need the required SRU information for this bug including how to reproduce to validate the fix has resolved this issue.

[Robie Basak (racb)]

Still awaiting SRU information please.

[Frode Nordahl (fnordahl)]

Description updated with SRU documentation, apologies for the delay.

[Brian Murray (brian-murray)]

Hello James, or anyone else affected,

Accepted ovn into focal-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/ovn/20.03.2-0ubuntu0.20.04.3 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.

[Frode Nordahl (fnordahl)]

Control test:
With basis in the OVN package currently in the Focal Main archive, I added only the functional test part of debian/patches/lp-1957817-ovn-northd-Add-localnet-ports-to-Multicast_Groups-cr.patch

## ----------------------- ##
## ovn 20.03.2 test suite. ##
## ----------------------- ##

OVN end-to-end tests

117: ovn -- IGMP snoop/querier/relay FAILED (ovs-macros.at:222)
118: ovn -- MLD snoop/querier/relay FAILED (ovs-macros.at:222)

## ------------- ##
## Test results. ##
## ------------- ##

ERROR: All 2 tests were run,
2 failed unexpectedly.

Now instead download source of the proposed package and build it:
## ----------------------- ##
## ovn 20.03.2 test suite. ##
## ----------------------- ##

...

117: ovn -- IGMP snoop/querier/relay ok
118: ovn -- MLD snoop/querier/relay ok

...
## ------------- ##
## Test results. ##
## ------------- ##

All 242 tests were successful.

[Launchpad Janitor (janitor)]

This bug was fixed in the package ovn - 20.03.2-0ubuntu0.20.04.3

---------------
ovn (20.03.2-0ubuntu0.20.04.3) focal; urgency=medium

  [ James Troup ]
  * Fix Multicast traffic between VMs using provider networks (LP: #1957817):
   - d/p/lp-1957817-ovn-northd-Add-localnet-ports-to-Multicast_Groups-cr.patch

  [ Frode Nordahl ]
  * Add support for PTR DNS requests (LP: #1857026):
    - d/p/lp-1857026-0001-DNS-Make-DNS-lookups-case-insensitive.patch
    - d/p/lp-1857026-0002-controller-Add-support-for-PTR-DNS-requests.patch

 -- Frode Nordahl <email address hidden> Fri, 25 Feb 2022 08:10:00 +0100

[Łukasz Zemczak (sil2100)]

The verification of the Stable Release Update for ovn has completed successfully and the package is now being released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.

[Corey Bryant (corey.bryant)]

Hello James, or anyone else affected,

Accepted ovn into ussuri-proposed. The package will build now and be available in the Ubuntu Cloud Archive in a few hours, and then in the -proposed repository.

Please help us by testing this new package. To enable the -proposed repository:

  sudo add-apt-repository cloud-archive:ussuri-proposed
  sudo apt-get update

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, and change the tag from verification-ussuri-needed to verification-ussuri-done. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-ussuri-failed. In either case, details of your testing will help us make a better decision.

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

[Corey Bryant (corey.bryant)]

The verification of the Stable Release Update for ovn has completed successfully and the package has now been released to -updates. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.

[Corey Bryant (corey.bryant)]

This bug was fixed in the package ovn - 20.03.2-0ubuntu0.20.04.3~cloud0
---------------

 ovn (20.03.2-0ubuntu0.20.04.3~cloud0) bionic-ussuri; urgency=medium
 .
   * New update for the Ubuntu Cloud Archive.
 .
 ovn (20.03.2-0ubuntu0.20.04.3) focal; urgency=medium
 .
   [ James Troup ]
   * Fix Multicast traffic between VMs using provider networks (LP: #1957817):
    - d/p/lp-1957817-ovn-northd-Add-localnet-ports-to-Multicast_Groups-cr.patch
 .
   [ Frode Nordahl ]
   * Add support for PTR DNS requests (LP: #1857026):
     - d/p/lp-1857026-0001-DNS-Make-DNS-lookups-case-insensitive.patch
     - d/p/lp-1857026-0002-controller-Add-support-for-PTR-DNS-requests.patch