netdev - Re: Cannot bind to IPv6 address in VRF

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Message-ID: <34c7b892-a1fc-a9b2-b1ef-848341f51d52@gmail.com>
Date:   Tue, 1 Jan 2019 09:24:15 -0700
From:   David Ahern <dsahern@...il.com>
To:     Ralf Jung <post@...fj.de>, netdev@...r.kernel.org
Cc:     Ondrej Zajicek <santiago@...reenet.org>, jan.matejka@....cz
Subject: Re: Cannot bind to IPv6 address in VRF

On 1/1/19 7:58 AM, Ralf Jung wrote:
> If instead, in the last line, I use the IPv6 address of eth0 (which is not
> inside this VRF), the `bind` call succeeds.  On the other hand, when I try using
> the eth0 IPv4 address in the first block, `bind` fails as expected because the
> address is not inside `vrf_freifunk`.
> If I replace `vrf_freifunk` by `tun-up-a_ak` (which is more like what Bird
> does), the behavior remains the same.
> 
> I think this is a kernel bug, it seems like setting `SO_BINDTODEVICE` on the
> IPv6 socket is just ignored entirely.
> 

I see the problem. The check on the address bind is not considering the
L3 domain - or even the device at all. That's why binding to an address
in the default VRF works, but bind to an address in a VRF fails
(requires an l3mdev match). Not sure how this has fallen through the
cracks over the last 3 years.

I will send a patch. Most likely will not happen until tomorrow.