svn commit: r353057 - head/sys/net

[Allan Jude]

On 2019-10-04 08:57, Kyle Evans wrote:
> On Thu, Oct 3, 2019 at 12:54 PM Kyle Evans <kevans at freebsd.org> wrote:
>>
>> Author: kevans
>> Date: Thu Oct  3 17:54:00 2019
>> New Revision: 353057
>> URL: https://svnweb.freebsd.org/changeset/base/353057
>>
>> Log:
>>   if_tuntap: create /dev aliases when a tuntap device gets renamed
>>
>>   Currently, if you do:
>>
>>   $ ifconfig tun0 create
>>   $ ifconfig tun0 name wg0
>>   $ ls -l /dev | egrep 'wg|tun'
>>
>>   You will see tun0, but no wg0. In fact, it's slightly more annoying to make
>>   the association between the new name and the old name in order to open the
>>   device (if it hadn't been opened during the rename).
>>
>>   Register an eventhandler for ifnet_arrival_events and catch interface
>>   renames. We can determine if the ifnet is a tun easily enough from the
>>   if_dname, which matches the cevsw.d_name from the associated tuntap_driver.
>>
>>   Some locking dance is required because renames don't require the device to
>>   be opened, so it could go away in the middle of handling the ioctl, but as
>>   soon as we've verified this isn't the case we can attempt to busy the tun
>>   and either bail out if the tun device is dying, or we can proceed with the
>>   rename.
>>
>>   We only create these aliases on a best-effort basis. Renaming a tun device
>>   to "usbctl", which doesn't exist as an ifnet but does as a /dev, is clearly
>>   not that disastrous, but we can't and won't create a /dev for that.
>>
> 
> It's been brought to my attention that I actually had a PR that I took
> six months ago that this should've belonged to.
> 
> PR: 219746
> 

Thanks for this, I was having similar problems with this trying to use
wireguard inside a VNET jail, so it was even harder to find and destroy
the correct interface.

-- 
Allan Jude

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