Re: ip netns del zaps wg link

[Harry G Coin <hgcoin@gmail.com>]

On 7/14/23 05:27, Maarten de Vries wrote:
> On 18/05/2023 01:13, Harry G Coin wrote:
>> First, Hi and thanks for all the effort!
>>
>> At least on Ubuntu latest LTS:  As advertised, if a wireguard link 
>> gets created by systemd/networkd, then set into a different net 
>> namespace, all works well.
>>
>> However, if that namespace is deleted, the link appears to be 'gone 
>> forever'.  Other link types reappear in the primary namespace when 
>> the namespace they are in gets deleted.   I'm not sure whether the 
>> link retains its 'up' or 'down' state when the namespace it's in gets 
>> deleted and reset to primary.  Not a big deal, doesn't happen often.
>>
>> This is 100% repeatable.   Some other answer than 'inaccessible until 
>> the next reboot' would be nice.
>>
>>
>
> Hi,
>
> This behavior is exactly what I would expect. I'm using namespaces to 
> restrict access to a wireguard link. If the namespace gets destroyed, 
> I absolutely do not want other programs to have access to the 
> wireguard link.
>
> You can simply re-create the wireguard link to use it again. This may 
> not be the most convenient for you, but your use case seems to be a 
> bit unconventional: you are moving and deleting a resource created by 
> systemd and/or networkd manually. You are mixing automatic and manual 
> management, so there is a risk of breaking the automatic management.
>
> Alternatively, you could move the interface back before deleting the 
> namespace.
>
> Kind regards,
>
> Maarten de Vries
>
Hi,

It's worth thinking about the only means by which a namespace 'gets 
destroyed'.

The point of systemd/networkd for most of us is similarity and 
convenience and uniformity in initialization across interface device 
types.  That frees later choices in nic management to involve only the 
detail specific to those choices.  Remember systemd/networkd (can be 
just one-and-done setup time management) is a very different thing than 
NetworkManager (Automatic active ongoing management).  Someday I hope 
systemd/networkd adds namespace comprehension.

As wireguard and namespaces management are both limited to the root 
user, who presumably is aware of the security implications involved, and 
wireguard's birth in the initial namespace is a selling point no matter 
how it moves among namespaces later: allowing wireguard interfaces to 
behave like all other interfaces when a namespace is destroyed  (moving 
back to the namespace where it was born and to which it retains 
connection anyhow) avoids imposing further 'wireguard only' admin 
burden.   It might be convenient to automatically set the wireguard link 
'down' as the interface transitions back from the namespace being 
destroyed to the primary so as to avoid any possibility of overlapping 
existing entries in the primary routing table.  But destroying the 
interface altogether generates admin burden beyond need.

Thanks for all the wireguard work!

Harry Coin