[CRIU] RFC: Add owner user namespace to tty_struct

[Matt Brown]

On 5/29/17 7:22 AM, Cyrill Gorcunov wrote:
> On Mon, May 29, 2017 at 02:09:40PM +0300, Pavel Emelyanov wrote:
>> On 05/29/2017 01:00 PM, Cyrill Gorcunov wrote:
>>> On Mon, May 29, 2017 at 12:43:52PM +0300, Pavel Emelyanov wrote:
>>>>>
>>>>> Hi Matt! Currently we don't use fake input in criu so at moment it won't
>>>>> affect us anyhow, but in longterm I expect more owner_user_ns testing may
>>>>> appear. Thus we will need to know which owner tty belong to. I think we
>>>>> may extend tty_fops and use show_fdinfo method to print owner_user_ns.
>>>>
>>>> We have similar problem with net_device:net pairing and with userns:<any other ns>
>>>> one -- we need to know which object belongs to which. For the net_device:net case
>>>> there has appeared a netdev ioctl, that results in an opened namespace file, just
>>>> like if we did open("/proc/pid/ns/net"). I think the same API would be more convenient
>>>> for tty:userns. All the more so there's already plenty of ioctls for ttys :)
>>>
>>> Mind to point which netdev ioctl it is?
>>
>> It's SIOCGSKNS. And I've made a mistake when told it was netdev->netns, it's
>> socket->netns mapper. Still, it returns an open file :)
> 
> Look good. Yup we could have the same for ttys I think.
> 

Thanks for all the feedback!

I will definitely look into the SIOCGSKNS ioctl and see if I can whip up
something similar for tty->owner_user_ns. In the mean time, do you feel OK with
my patch landing without this since you don't currently do input faking in criu?

Thanks,
Matt Brown