[Bug 1662324] Re: linux bridge agent disables ipv6 before adding an ipv6 address

Mon Jun 22 14:47:26 UTC 2020

Since the patch is not entirely trivial, since some of the methods have
had their argument lists changed, I would appreciate if we had a bit
more regression potential analysis. What do you think could, in the
worst unpredictable scenario, break after this is released? In which
parts should we expect issues? Could it somehow affect non IPv6
scenarios?

** Changed in: neutron (Ubuntu Xenial)
       Status: In Progress => Incomplete

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Title:
  linux bridge agent disables ipv6 before adding an ipv6 address

Status in Ubuntu Cloud Archive:
  Fix Released
Status in Ubuntu Cloud Archive mitaka series:
  In Progress
Status in neutron:
  Fix Released
Status in neutron package in Ubuntu:
  Fix Released
Status in neutron source package in Xenial:
  Incomplete

Bug description:
  [Impact]
  When using linuxbridge and after creating network & interface to ext-net, disable_ipv6 is 1. then linuxbridge-agent doesn't add ipv6 properly to newly created bridge.

  [Test Case]

  1. deploy basic mitaka env
  2. create external network(ext-net)
  3. create ipv6 network and interface to ext-net
  4. check if related bridge has ipv6 ip
  - no ipv6 originally
  or
  - cat /proc/sys/net/ipv6/conf/[BRIDGE]/disable_ipv6

  after this commit, I was able to see ipv6 address properly.

  [Regression]
  This has been patched in newer releases of neutron for a while regression potential of the backport should be fairly low. You need to restart neutron-linuxbridge-agent after applying the fix adn then there could be short downtime needed.

  [Others]

  -- original description --

  Summary:
  ========
  I have a dual-stack NIC with only an IPv6 SLAAC and link local address plumbed. This is the designated provider network nic. When I create a network and then a subnet, the linux bridge agent first disables IPv6 on the bridge and then tries to add the IPv6 address from the NIC to the bridge. Since IPv6 was disabled on the bridge, this fails with 'RTNETLINK answers: Permission denied'. My intent was to create an IPv4 subnet over this interface with floating IPv4 addresses for assignment to VMs via this command:
    openstack subnet create --network provider \
      --allocation-pool start=10.54.204.200,end=10.54.204.217 \
      --dns-nameserver 69.252.80.80 --dns-nameserver 69.252.81.81 \
      --gateway 10.54.204.129 --subnet-range 10.54.204.128/25 provider

  I don't know why the agent is disabling IPv6 (I wish it wouldn't),
  that's probably the problem. However, if the agent knows to disable
  IPv6 it should also know not to try to add an IPv6 address.

  Details:
  ========
  Version: Newton on CentOS 7.3 minimal (CentOS-7-x86_64-Minimal-1611.iso) as per these instructions: http://docs.openstack.org/newton/install-guide-rdo/

  Seemingly relevant section of /var/log/neutron/linuxbridge-agent.log:
  2017-02-06 15:09:20.863 1551 INFO neutron.plugins.ml2.drivers.linuxbridge.agent.arp_protect [req-4917c507-369e-4a36-a381-e8b287cbc988 - - - - -] Skipping ARP spoofing rules for port 'tap3679987e-ce' because it has port security disabled
  2017-02-06 15:09:20.863 1551 DEBUG neutron.agent.linux.utils [req-4917c507-369e-4a36-a381-e8b287cbc988 - - - - -] Running command: ['ip', '-o', 'link', 'show', 'tap3679987e-ce'] create_process /usr/lib/python2.7/site-packages/neutron/agent/linux/utils.py:89
  2017-02-06 15:09:20.870 1551 DEBUG neutron.agent.linux.utils [req-4917c507-369e-4a36-a381-e8b287cbc988 - - - - -] Exit code: 0 execute /usr/lib/python2.7/site-packages/neutron/agent/linux/utils.py:146
  2017-02-06 15:09:20.871 1551 DEBUG neutron.agent.linux.utils [req-4917c507-369e-4a36-a381-e8b287cbc988 - - - - -] Running command: ['ip', 'addr', 'show', 'eno1', 'scope', 'global'] create_process /usr/lib/python2.7/site-packages/neutron/agent/linux/utils.py:89
  2017-02-06 15:09:20.878 1551 DEBUG neutron.agent.linux.utils [req-4917c507-369e-4a36-a381-e8b287cbc988 - - - - -] Exit code: 0 execute /usr/lib/python2.7/site-packages/neutron/agent/linux/utils.py:146
  2017-02-06 15:09:20.879 1551 DEBUG neutron.agent.linux.utils [req-4917c507-369e-4a36-a381-e8b287cbc988 - - - - -] Running command: ['ip', 'route', 'list', 'dev', 'eno1', 'scope', 'global'] create_process /usr/lib/python2.7/site-packages/neutron/agent/linux/utils.py:89
  2017-02-06 15:09:20.885 1551 DEBUG neutron.agent.linux.utils [req-4917c507-369e-4a36-a381-e8b287cbc988 - - - - -] Exit code: 0 execute /usr/lib/python2.7/site-packages/neutron/agent/linux/utils.py:146
  2017-02-06 15:09:20.886 1551 DEBUG neutron.agent.linux.utils [req-4917c507-369e-4a36-a381-e8b287cbc988 - - - - -] Running command (rootwrap daemon): ['ip', 'link', 'set', 'brqe1623c94-1f', 'up'] execute_rootwrap_daemon /usr/lib/python2.7/site-packages/neutron/agent/linux/utils.py:105
  2017-02-06 15:09:20.895 1551 DEBUG neutron.plugins.ml2.drivers.linuxbridge.agent.linuxbridge_neutron_agent [req-4917c507-369e-4a36-a381-e8b287cbc988 - - - - -] Starting bridge brqe1623c94-1f for subinterface eno1 ensure_bridge /usr/lib/python2.7/site-packages/neutron/plugins/ml2/drivers/linuxbridge/agent/linuxbridge_neutron_agent.py:367
  2017-02-06 15:09:20.895 1551 DEBUG neutron.agent.linux.utils [req-4917c507-369e-4a36-a381-e8b287cbc988 - - - - -] Running command (rootwrap daemon): ['brctl', 'addbr', 'brqe1623c94-1f'] execute_rootwrap_daemon /usr/lib/python2.7/site-packages/neutron/agent/linux/utils.py:105
  2017-02-06 15:09:20.905 1551 DEBUG neutron.agent.linux.utils [req-4917c507-369e-4a36-a381-e8b287cbc988 - - - - -] Exit code: 0 execute /usr/lib/python2.7/site-packages/neutron/agent/linux/utils.py:146
  2017-02-06 15:09:20.905 1551 DEBUG neutron.agent.linux.utils [req-4917c507-369e-4a36-a381-e8b287cbc988 - - - - -] Running command (rootwrap daemon): ['brctl', 'setfd', 'brqe1623c94-1f', '0'] execute_rootwrap_daemon /usr/lib/python2.7/site-packages/neutron/agent/linux/utils.py:105
  2017-02-06 15:09:20.909 1551 DEBUG neutron.agent.linux.utils [req-4917c507-369e-4a36-a381-e8b287cbc988 - - - - -] Exit code: 0 execute /usr/lib/python2.7/site-packages/neutron/agent/linux/utils.py:146
  2017-02-06 15:09:20.910 1551 DEBUG neutron.agent.linux.utils [req-4917c507-369e-4a36-a381-e8b287cbc988 - - - - -] Running command (rootwrap daemon): ['brctl', 'stp', 'brqe1623c94-1f', 'off'] execute_rootwrap_daemon /usr/lib/python2.7/site-packages/neutron/agent/linux/utils.py:105
  2017-02-06 15:09:20.913 1551 DEBUG neutron.agent.linux.utils [req-4917c507-369e-4a36-a381-e8b287cbc988 - - - - -] Exit code: 0 execute /usr/lib/python2.7/site-packages/neutron/agent/linux/utils.py:146
  2017-02-06 15:09:20.914 1551 DEBUG neutron.agent.linux.utils [req-4917c507-369e-4a36-a381-e8b287cbc988 - - - - -] Running command (rootwrap daemon): ['sysctl', '-w', 'net.ipv6.conf.brqe1623c94-1f.disable_ipv6=1'] execute_rootwrap_daemon /usr/lib/python2.7/site-packages/neutron/agent/linux/utils.py:105
  2017-02-06 15:09:20.919 1551 DEBUG neutron.agent.linux.utils [req-4917c507-369e-4a36-a381-e8b287cbc988 - - - - -] Exit code: 0 execute /usr/lib/python2.7/site-packages/neutron/agent/linux/utils.py:146
  2017-02-06 15:09:20.919 1551 DEBUG neutron.agent.linux.utils [req-4917c507-369e-4a36-a381-e8b287cbc988 - - - - -] Running command (rootwrap daemon): ['ip', 'link', 'set', 'brqe1623c94-1f', 'up'] execute_rootwrap_daemon /usr/lib/python2.7/site-packages/neutron/agent/linux/utils.py:105
  2017-02-06 15:09:20.922 1551 DEBUG neutron.agent.linux.utils [req-4917c507-369e-4a36-a381-e8b287cbc988 - - - - -] Exit code: 0 execute /usr/lib/python2.7/site-packages/neutron/agent/linux/utils.py:146
  2017-02-06 15:09:20.923 1551 DEBUG neutron.plugins.ml2.drivers.linuxbridge.agent.linuxbridge_neutron_agent [req-4917c507-369e-4a36-a381-e8b287cbc988 - - - - -] Done starting bridge brqe1623c94-1f for subinterface eno1 ensure_bridge /usr/lib/python2.7/site-packages/neutron/plugins/ml2/drivers/linuxbridge/agent/linuxbridge_neutron_agent.py:379
  2017-02-06 15:09:20.923 1551 DEBUG neutron.agent.linux.utils [req-4917c507-369e-4a36-a381-e8b287cbc988 - - - - -] Running command (rootwrap daemon): ['ip', '-6', 'addr', 'add', '2001:558:1046:12:cfb6:e0b9:d25f:4118/64', 'scope', 'global', 'dev', 'brqe1623c94-1f'] execute_rootwrap_daemon /usr/lib/python2.7/site-packages/neutron/agent/linux/utils.py:105
  2017-02-06 15:09:20.927 1551 ERROR neutron.agent.linux.utils [req-4917c507-369e-4a36-a381-e8b287cbc988 - - - - -] Exit code: 2; Stdin: ; Stdout: ; Stderr: RTNETLINK answers: Permission denied

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