Geneve tunnels don't work when ipv6 is disabled
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
linux (Ubuntu) |
Fix Released
|
High
|
Nivedita Singhvi | ||
Xenial |
Fix Released
|
High
|
Nivedita Singhvi | ||
Bionic |
Fix Released
|
High
|
Nivedita Singhvi | ||
Cosmic |
Fix Released
|
High
|
Nivedita Singhvi | ||
Disco |
Fix Released
|
High
|
Nivedita Singhvi |
Bug Description
SRU Justification
Impact: Cannot create geneve tunnels if ipv6 is disabled dynamically.
Fix:
Fixed by upstream commit in v5.0:
Commit: cf1c9ccba7308e4
"geneve: correctly handle ipv6.disable module parameter"
Hence available in Disco and later; required in X,B,C.
Testcase:
1. Boot with "ipv6.disable=1"
2. Then try and create a geneve tunnel using:
# ovs-vsctl add-br br1
# ovs-vsctl add-port br1 geneve1 -- set interface geneve1
type=geneve options:
Regression Potential: Low, only geneve tunnels when ipv6 dynamically
disabled, current status is it doesn't work at all.
Other Info:
* Mainline commit msg includes reference to a fix for
non-metadata tunnels (infrastructure is not yet in
our tree prior to Disco), hence not being included
at this time under this case.
At this time, all geneve tunnels created as above
are metadata-enabled.
---
[Impact]
When attempting to create a geneve tunnel on Ubuntu 16.04 Xenial, in
an OS environment with open vswitch, where ipv6 has been disabled,
the create fails with the error :
“ovs-vsctl: Error detected while setting up 'geneve0': could not
add network device geneve0 to ofproto (Address family not supported
by protocol)."
[Fix]
There is an upstream commit for this in v5.0 mainline (and in Disco and later Ubuntu kernels).
"geneve: correctly handle ipv6.disable module parameter"
Commit: cf1c9ccba7308e4
This fix is needed on all our series prior to Disco
and the v5.0 kernel: X, C, B. It is identical to the
fix we implemented and tested internally with, but had
not pushed upstream yet.
[Test Case]
(Best to do this on a kvm guest VM so as not to interfere with
your system's networking)
1. On any Ubuntu Xenial kernel, disable ipv6. This example
is shown with the 4.15.0-23-generic kernel (which differs
slightly from 4.4.x in symptoms):
- Edit /etc/default/grub to add the line:
- # update-grub
- Reboot
2. Install OVS
# apt install openvswitch-switch
3. Create a Geneve tunnel
# ovs-vsctl add-br br1
# ovs-vsctl add-port br1 geneve1 -- set interface geneve1
type=geneve options:
(where remote_ip is the IP of the other host)
You will see the following error message:
"ovs-vsctl: Error detected while setting up 'geneve1'.
See ovs-vswitchd log for details."
From /var/log/
"2018-07-
failed to add geneve1 as port: Address family not supported
by protocol"
You will notice from the "ifconfig" output that the device
genev_sys_6081 is not created.
If you do not disable IPv6 (remove ipv6.disable=1 from
/etc/default/grub + update-grub + reboot), the same
'ovs-vsctl add-port' command completes successfully.
You can see that it is working properly by adding an
IP to the br1 and pinging each host.
On kernel 4.4 (4.4.0-
happen using the 'ovs-vsctl add-port' command, no warning is
shown in ovs-vswitchd.log, but the device genev_sys_6081 is
also not created and ping test won't work.
With the fixed test kernel, the interfaces and tunnel
is created successfully.
[Regression Potential]
* Low -- affects the geneve driver only, and when ipv6 is
disabled, and since it doesn't work in that case at all,
this fix gets the tunnel up and running for the common case.
[Other Info]
* Analysis
Geneve tunnels should work with either IPv4 or IPv6 environments
as a design and support principle.
Currently, however, what's in the implementation requires support
for ipv6 for metadata-based tunnels which geneve is:
rather than:
a) ipv4 + metadata // whether ipv6 compiled or dynamically disabled
b) ipv4 + metadata + ipv6
What enforces this in the current 4.4.0-x code when opening a Geneve
tunnel is the following in geneve_open() :
bool ipv6 = geneve-
bool metadata = geneve->collect_md;
...
#if IS_ENABLED(
if (ipv6 || metadata)
ret = geneve_
#endif
if (!ret && (!ipv6 || metadata))
ret = geneve_
CONFIG_IPV6 is enabled, IPv6 is disabled at boot, but
even though ipv6 is false, metadata is always true
for a geneve open as it is set unconditionally in
ovs:
In /lib/dpif_
case OVS_VPORT_
nl_msg_
The second argument of geneve_sock_add is a boolean
value indicating whether it's an ipv6 address family
socket or not, and we thus incorrectly pass a true
value rather than false.
The current "|| metadata" check is unnecessary and incorrectly
sends the tunnel creation code down the ipv6 path, which
fails subsequently when the code expects an ipv6 family socket.
* This issue exists in all versions of the kernel upto present
mainline and net-next trees.
* Testing with a trivial patch to remove that and make
similar changes to those made for vxlan (which had the
same issue) has been successful. Patches for various
versions to be attached here soon.
* Example Versions (bug exists in all versions of Ubuntu
and mainline):
$ uname -r
4.4.0-135-generic
$ lsb_release -rd
Description: Ubuntu 16.04.5 LTS
Release: 16.04
$ dpkg -l | grep openvswitch-switch
ii openvswitch-switch 2.5.4-0ubuntu0.
CVE References
tags: | added: geneve kernel-bug |
Changed in linux (Ubuntu): | |
importance: | Undecided → Medium |
status: | Confirmed → Triaged |
tags: | added: kernel-da-key |
description: | updated |
Changed in linux (Ubuntu Bionic): | |
status: | New → In Progress |
importance: | Undecided → High |
assignee: | nobody → Nivedita Singhvi (niveditasinghvi) |
description: | updated |
Changed in linux (Ubuntu Disco): | |
status: | In Progress → Fix Released |
description: | updated |
description: | updated |
description: | updated |
description: | updated |
description: | updated |
description: | updated |
tags: | added: cosmic xenial |
Changed in linux (Ubuntu Bionic): | |
status: | In Progress → Fix Committed |
Changed in linux (Ubuntu Cosmic): | |
status: | In Progress → Fix Committed |
tags: | added: sts |
Changed in linux (Ubuntu Xenial): | |
status: | In Progress → Fix Committed |
Changed in linux (Ubuntu Xenial): | |
status: | Fix Committed → Confirmed |
status: | Confirmed → Won't Fix |
status: | Won't Fix → Fix Committed |
tags: | added: cscc |
This bug is missing log files that will aid in diagnosing the problem. While running an Ubuntu kernel (not a mainline or third-party kernel) please enter the following command in a terminal window:
apport-collect 1794232
and then change the status of the bug to 'Confirmed'.
If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.
This change has been made by an automated script, maintained by the Ubuntu Kernel Team.