Problems with Ubuntu 16.04 kernels and wireguard 1.0.20200611

[Gregory ORIOL]

Hi,

Thanks for your feedback!

Couldn't that issue be fixed by adapting the IF condition that has been
changed in commit e24c9a9265af40781fa27b5de11dd5b78925c5be?
I know it's not very practical to support/check this, plus it's not
wireguard's fault, but that will likely cause trouble to other users too.

We could obviously wait a few weeks with a broken apt upgrade state
until a new new kernel version is released and then switch to it, and
remove the old ones, so then we will have an n-1 kernel -184 working and
the new-new one as current. But that feels like a very unstable
situation for our systems until then...

Regards,
Gregory


Jason A. Donenfeld a écrit le 17/06/2020 à 10:13 :

> Hi Gregory,
>
> On Wed, Jun 17, 2020 at 2:01 AM Gregory ORIOL <fortin81 at gmail.com> wrote:
>> Since commit e24c9a9265af40781fa27b5de11dd5b78925c5be to
>> wireguard-linux-compat with a fix for some Ubuntu versions, we are
>> experiencing a problem with some older, but still LTS, versions of
>> Ubuntu 16.04: older kernels 4.4.0-148, 4.4.0-166 fail to build with
>> wireguard 1.0.20200611
>>
>> So, any system running an (or still having an installed) "older" kernel
>> and doing an apt upgrade to install wireguard 1.0.20200611 would fail
>> during the wireguard dkms step, while trying to build wireguard for all
>> the kernels available.
>>
>> The problem gets more problematic when a newer kernel 4.4.0-184 gets
>> installed with the same apt upgrade: then, trying to downgrade wireguard
>> also fails; none of the 1.0.20200611 or 1.0.20200520 versions work
>> anymore with this combination of old/new kernels...
>>
>> To recap :
>> # wireguard 1.0.20200520
>>  - ok with kernels 4.4.0-148, 4.4.0-166
>>  - fails with kernel 4.4.0-184
>> # wireguard 1.0.20200611
>>  - fails with kernels 4.4.0-148, 4.4.0-166
>>  - ok with kernel 4.4.0-184
>>
>> (nb: we see it now with -184 but it could have started with an earlier
>> version)
>>
>> We could partially fix this by manually getting each deb/src and doing
>> dkms install:
>> dkms install wireguard/1.0.20200520 -k 4.4.0-148-generic
>> dkms install wireguard/1.0.20200611 -k 4.4.0-184-generic
>> ...
>> But apt upgrade is still broken.
>>
>> While we could boot onto the newer kernel and remove the older ones to
>> get rid of the problem, this situation would prevent from having a
>> "previous working" kernel on the system, which is not very safe.
>>
>> Could there be a fix for this made to wireguard-linux-compat for those
>> versions?
> Unfortunately, I don't have a super good solution for you right now.
> The wireguard-linux-compat repo is developed against the latest Ubuntu
> kernels that they put out once every three weeks. You can see them
> being tested at the bottom of
> <https://www.wireguard.com/build-status/>. The backport against
> upstream mainline kernels is z-granular (for an x.y.z versioning
> scheme), but Ubuntu's release cycle and versioning scheme is a bit too
> chaotic to make it reasonable to try to manage all the differences
> between their kernels every three weeks. So for distro kernels --
> Ubuntu, RHEL, Debian, etc -- we typically just develop against the
> latest one, and try to make sure that we release it at the right time
> so users aren't caught with no working version. This means,
> unfortunately, that when there are badly breaking changes, like in
> this last cycle, you have to uninstall the old kernels or mask them
> from dkms, in order to get dkms to avoid building for them and only
> building for the new kernel. There might be other more complicated
> solutions that closely track version dependencies or do compile time
> feature probing, but that comes with a maintenance burden far too
> arduous for a distro frankenkernel.
>
> But there is hope!
>
> Canonical is adding WireGuard to 18.04 and 16.04, and this is coming
> in two steps:
>
> Step 1) The wireguard-dkms and wireguard-tools packages will be added
> to the package archives, so that you won't have to use the PPA. This
> means that Canonical's kernel team will include wireguard-dkms in
> their development tests, so that they won't accidentally ship kernels
> with build breakage, like what you experienced last week.
>
> Step 2) The wireguard-dkms package will get built by Canonical,
> signed, and shipped alongside the other modules, so that you won't
> have to install wireguard-dkms, and it will just come out of the box
> with the normal kernel updates. This is already the case with 20.04
> and 19.10. They're working on it now for 18.04, and I really really
> hope to see that happen by the next cycle. And maybe if we ask apw
> (CC'd) nicely, he'll even do it for 16.04 too.
>
> Regards,
> Jason