Re: Help with Ubuntu Touch update to NM 1.2

On 05/11/2016 02:19 AM, Thomas Haller wrote:
On Tue, 2016-05-10 at 20:49 -0400, Tony Espy wrote:

Hi Tony,

After we recently landed NM 1.1.93 to Ubuntu 16.04 desktop, I
working on back-porting it to Vivid/15.04 for use by Ubuntu Touch
is still currently pinned to a 0.9.10 version of NM.

Very little needed to be changed to get it running.

One thing to note is that most of the devices running Touch are on
kernels ( mako is the oldest at 3.4, some are 3.10 ), so all output

18:19:56 <warn> device (wlan0): The kernel does not support extended
IFA_FLAGS needed by NM for IPv6 private addresses. This feature is

In the very past, NM used kernel to do autoconf (accept_ra). Already in
0.9.10, NM switched to using libndp and do it in user-space.

That originally broke IPv6 private addresses, and it was not fixed
until kernel added IFA_F_MANAGETEMPADDR. Thus, on your 0.9.10, IPv6
temporary addresss are not working already know (or do they?)

Thanks for the reply Thomas!

As mentioned, we currently don't perform in-depth IPv6 testing on touch, so it's very likely that temp addresses have never worked properly.

It's only that NM now warns about that...


During testing, we ran into problems with OpenVPN that seem to be
related to the re-factored netlink logic in NMLinuxPlatform and the
older kernels we're running.

We see two failures, the first occurs when the VPN connection
an IPv6 address add.  As the VPN specifies a unique Internal Address
Internal Point to Point address (or peer address), the latter is used
NM to build the IFA_ADDRESS attribute appended to the NEWADDR
The kernel rejects this with EINVAL.

Running 0.9.10x, the address is added, it just doesn't include the
address, and uses address for the IFA_ADDRESS attribute.

We also see quite a few of the same types of add IPv6 address
happening on a periodic basis with no VPN involved, which are
triggerd by lease renewals.

I was able to patch 1.1.93 to mimic the 0.9.10 behavior ( ie. never
peer_address for IFA_ADDRESS ) and the errors in syslog
disapper.  That
said, I'm not 100% the IPv6 configuration was ever *working*
however with this path our syslog isn't flooded with errors.

(just repeating what I said yesterday on IRC, for the list)

Older kernels don't support peer-addresses for IPv6. That was added
before, IFA_LOCAL and IFA_ADDRESS cannot differ.

With 1.2, nm-openvpn tells NetworkManager to consider the peer when
adding an IPv6 addresss. This was not present in 0.9.10 either, it was
added by commit
(grep for "ifconfig_ipv6_remote")

Unfortunately, it's not easily possible to detect at runtime whether
kernel support it or not.

I am not sure that patching nm-linux-platform.c to silently ignore the
peer is correct. Maybe it's better to patch nm-openvpn (and all
componnets) not to set IPv6 peer-addresses...
After all, if nm-openvpn requests to add such a IPv6 address,
NetworkManager/kernel should either comply or fail.
I dunno at which place this should be fixed.

After some discussion this morning, we're going to back out this portion of the patch.

The second failure is adding an IPv4 address that already
exists.  The
old code base had explicit handling for this case ( EEXISTS ) and
treat the operation as SUCCESS.  When I added extra logic to handle
EEXISTS in do_add_addroute ( in nm-linux-platform.c ), the IPv4
also disappeared, and I found that the VPN was now properly

On some of our newer devices, this IPv4 error doesn't occur, however
workaround appears to be a no-op on these devices.

Why does that happen? NM sets the netlink flags to NLM_F_CREATE|NLM_F_REPLACE, so kernel should replace the 
Which kernel version are you using precisely (which Ubuntu package)?

It happens because we're using kernels based on the Android BSPs for the hardware.

This only fails on some of the older devices we support ( eg. mako, krillin ). Devices with newer kernels and/or from different ODMs don't exhibit this behavior.

In this case, without this patch, OpenVPN is broken, so we're going to include this in our update, as on newer devices, the error won't be returned.

Does `make check` pass? Let's first add a test that shows the failure.

Yes, our PPA builds run `make check` and no failures are reported.

Regarding adding a test, yes that sounds like a good first step.


At this

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