Linux Virtualization - Aug 2023 - [PATCH v3 0/3] vduse: add support for networking devices

On Tue, Aug 29, 2023 at 03:34:06PM +0200, Maxime Coquelin
wrote:
> 
> 
> On 8/11/23 00:00, Jakub Kicinski wrote:
> > On Thu, 10 Aug 2023 17:42:11 -0400 Michael S. Tsirkin wrote:
> > > > Directly into the stack? I thought VDUSE is vDPA in user
space,
> > > > meaning to get to the kernel the packet has to first go thru
> > > > a virtio-net instance.
> > > 
> > > yes. is that a sufficient filter in your opinion?
> > 
> > Yes, the ability to create the device feels stronger than CAP_NET_RAW,
> > and a bit tangential to CAP_NET_ADMIN. But I don't have much
practical
> > experience with virt so no strong opinion, perhaps it does make sense
> > for someone's deployment? Dunno..
> > 
> 
> I'm not sure CAP_NET_ADMIN should be required for creating the VDUSE
> devices, as the device could be attached to vhost-vDPA and so not
> visible to the Kernel networking stack.
> 
> However, CAP_NET_ADMIN should be required to attach the VDUSE device to
> virtio-vdpa/virtio-net.
> 
> Does that make sense?
> 
> Maxime
OK. How are we going to enforce it?
Also, we need a way for selinux to enable/disable some of these things
but not others.

-- 
MST

On 8/29/23 19:05, Michael S. Tsirkin wrote:
> On Tue, Aug 29, 2023 at 03:34:06PM +0200, Maxime Coquelin wrote:
>>
>>
>> On 8/11/23 00:00, Jakub Kicinski wrote:
>>> On Thu, 10 Aug 2023 17:42:11 -0400 Michael S. Tsirkin wrote:
>>>>> Directly into the stack? I thought VDUSE is vDPA in user
space,
>>>>> meaning to get to the kernel the packet has to first go
thru
>>>>> a virtio-net instance.
>>>>
>>>> yes. is that a sufficient filter in your opinion?
>>>
>>> Yes, the ability to create the device feels stronger than
CAP_NET_RAW,
>>> and a bit tangential to CAP_NET_ADMIN. But I don't have much
practical
>>> experience with virt so no strong opinion, perhaps it does make
sense
>>> for someone's deployment? Dunno..
>>>
>>
>> I'm not sure CAP_NET_ADMIN should be required for creating the
VDUSE
>> devices, as the device could be attached to vhost-vDPA and so not
>> visible to the Kernel networking stack.
>>
>> However, CAP_NET_ADMIN should be required to attach the VDUSE device to
>> virtio-vdpa/virtio-net.
>>
>> Does that make sense?
>>
>> Maxime
> 
> OK. How are we going to enforce it?
Actually, it seems already enforced for all VDPA devices types.
Indeed, the VDPA_CMD_DEV_NEW Netlink command used to add the device to
the VDPA bus has the GENL_ADMIN_PERM flag set, and so require
CAT_NET_ADMIN.
> Also, we need a way for selinux to enable/disable some of these things
> but not others.
Ok, I can do it in a patch on top.
Do you have a pointer where it is done for Virtio Block devices?

Maxime