Re: [Qemu-devel] Re: [PATCH 0/4] net-bridge: rootless bridge support for qemu

[Michael S. Tsirkin]

On Wed, Nov 04, 2009 at 01:48:01PM -0600, Anthony Liguori wrote:
> Michael S. Tsirkin wrote:
>> On Tue, Nov 03, 2009 at 06:28:01PM -0600, Anthony Liguori wrote:
>>   
>>> This series solves a problem that I've been struggling with for a few years 
>>> now.
>>> One of the best things about qemu is that it's possible to run guests as an
>>> unprivileged user to improve security.  However, if you want to have your 
>>> guests
>>> communicate with the outside world, you're pretty much forced to run qemu as
>>> root.
>>>
>>> At least with KVM support, this is probably the most common use case which 
>>> means
>>> that most of our users are running qemu as root.  That's terrible.
>>>
>>> We address this problem by introducing a new network backend: -net bridge.  
>>> This
>>> backend is less flexible than -net tap because it relies on a helper with
>>> elevated privileges to do the heavy lifting of allocating and attaching a 
>>> tap
>>> device to a bridge.  We use a special purpose helper because we don't want
>>> to elevate the privileges of more generic tools like brctl.
>>>
>>> >From a user perspective, to use bridged networking with a guest, you 
>>> >simply use:
>>>
>>>   qemu -hda linux.img -net bridge -net nic
>>>
>>> And assuming a bridge is defined named qemubr0 and the administrator has 
>>> setup
>>> permissions accordingly, it will Just Work.  My hope is that distributions 
>>> will
>>> do this work as part of the qemu packaging process such that for most users,
>>> the out-of-the-box experience will also Just Work.
>>>
>>> More details are included in individual patches.  I broke up the helper into
>>> a series of patches to improve reviewabilty.
>>>     
>>
>> Would raw backend attached to a bridge mostly do the same?
>>   
>
> Well it doesn't really help with the issue of privileges which is what  
> this series is really about.
>
> Regards,
>
> Anthony Liguori

I note that by default you grant all users all access.
If you do that, just give them net cap admin already?

-- 
MST