Re: [RFC PATCH 2/3] netdev: kernel-only IFF_HIDDEN netdevice

[Siwei Liu <loseweigh@gmail.com>]

On Tue, Apr 3, 2018 at 6:04 PM, David Ahern <dsahern@gmail.com> wrote:
> On 4/3/18 9:42 AM, Jiri Pirko wrote:
>>>
>>> There are other use cases that want to hide a device from userspace. I
>>
>> What usecases do you have in mind?
>
> As mentioned in a previous response some kernel drivers create control
> netdevs. Just as in this case users should not be mucking with it, and
> S/W like lldpd should ignore it.
>
>>
>>> would prefer a better solution than playing games with name prefixes and
>>> one that includes an API for users to list all devices -- even ones
>>> hidden by default.
>>
>> Netdevice hiding feels a bit scarry for me. This smells like a workaround
>> for userspace issues. Why can't the netdevice be visible always and
>> userspace would know what is it and what should it do with it?
>>
>> Once we start with hiding, there are other things related to that which
>> appear. Like who can see what, levels of visibility etc...
>>
>
> I would not advocate for any API that does not allow users to have full
> introspection. The intent is to hide the netdev by default but have an
> option to see it.

I'm fine with having a link dump API to inspect the hidden netdev. As
said, the name for hidden netdevs should be in a separate device
namespace, and we did not even get closer to what it should look like
as I don't want to make it just an option for ip link. Perhaps a new
set of sub-commands of, say, 'ip device'.

-Siwei