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

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Date:   Wed, 4 Apr 2018 08:19:45 +0200
From:   Jiri Pirko <jiri@...nulli.us>
To:     David Ahern <dsahern@...il.com>
Cc:     Si-Wei Liu <si-wei.liu@...cle.com>, mst@...hat.com,
        stephen@...workplumber.org, alexander.h.duyck@...el.com,
        davem@...emloft.net, jesse.brandeburg@...el.com, kubakici@...pl,
        jasowang@...hat.com, sridhar.samudrala@...el.com,
        netdev@...r.kernel.org, virtualization@...ts.linux-foundation.org,
        virtio-dev@...ts.oasis-open.org
Subject: Re: [RFC PATCH 2/3] netdev: kernel-only IFF_HIDDEN netdevice

Wed, Apr 04, 2018 at 03:04:26AM CEST, dsahern@...il.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

virtio_net. Any other drivers?


>S/W like lldpd should ignore it.

It's just a matter of identification of the netdevs, so the user knows
what to do.


>
>> 
>>> 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.

As an administrator, I want to see all by default. I think it is
reasonable requirements. Again, this awfully smells like a workaround...