Bug#969365: USB-C dock lacks multicast Ethernet functionality (so IPv6 is broken)
Hi Santiago,
On Tue, Sep 01, 2020 at 01:01:27PM +0200, Santiago R.R. wrote:
> Source: linux
> Version: 4.19.118-2
> Severity: important
> Tags: ipv6 upstream fixed-upstream
>
> IPv6 connectivity (and other network protocols relying on multicast) are
> broken when using a Dell D6000 USB-C dock.
> Quoting Miguel Rodríguez that filed the equivalent bug in ubuntu:
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1779173:
>
> "Dell D6000 exposes a CDC_NCM device for Ethernet traffic. However,
> multicast Ethernet traffic is not processed making IPv6 not functional.
> Other services, like mDNS used for LAN service discovery are also
> hindered.
>
> The actual reason is that CDC_NCM driver was not processing requests to
> filter (admit) multicast traffic. I provide two patches to the linux
> kernel that admit all Ethernet multicast traffic whenever a multicast
> group is being joined.
>
> The solution is not optimal, as it makes the system receive more traffic
> than that strictly needed, but otherwise this only happens when the
> computer is connected to a dock and thus is running on AC power. I
> believe it is not worth the hassle to join only the requested groups.
> This is the same that is done in the CDN_ETHER driver."
>
> The patches proposed by Miguel Rodríguez have been merged upstream, and
> are part of 5.9-rc1 now. C.f. commits:
> 37a2ebdd9e597ae1a0270ac747883ea8f6f767b6
> e10dcb1b6ba714243ad5a35a11b91cc14103a9a9
> e506addeff844237d60545ef4f6141de21471caf
> 0226009ce0f6089f9b31211f7a2703cf9a327a01
Thanks for the report, if I'm not mistaken this is the same as
#965074. Can you request upstream backports of the needed fixes into
the applicable stable releases (and as I understand you back to
v4.19.y)?
Regards,
Salvatore
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