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

[Avi Kivity <avi@redhat.com>]

On 11/05/2009 04:50 PM, Anthony Liguori wrote:
> Avi Kivity wrote:
>> On 11/05/2009 04:33 PM, Avi Kivity wrote:
>>> and concerned that we're loosening security for qemu non-users.
>>>
>>
>> I see you've addressed this via an acl system.  Still, this is IMO 
>> should be outside qemu, esp. as security is now much more than 
>> users/groups (i.e. selinux and friends).
>
> Actually, I think this model is pretty close to what the latest crazes 
> are in the security world.

I think we need to isolate qemu for these crazes.  First, we're hardly 
security experts here.  Second, anything we do will be bad for someone.  
Third, security models vary across distributions and time.

> The model you're advocating (privileged process handing over a fd) is 
> not as secure because it requires that the management daemon runs as a 
> privileged user.

Or it can acquire an fd from a privileged helper and pass it on or 
conjure it some other way.

>   There's nothing about this that prevents the use of a management 
> framework.  In fact, had this existed when libvirt was first written, 
> I'd hope libvirt would have used this mechanism instead of fd 
> inheritance.
>
> Management software is really just another user.  We really want 
> management software to run unprivileged as much as possible.

I'd like to see qemu confined to managing a single guest and not expand 
to system management.  We have enough to do without taking over 
management systems and security.

Bridged network configuration is painful now, but only for a handful of 
users (us developers).  For the vast majority it is handled behind their 
back by management, which has to deal with a bunch of privileged stuff 
anyway (assigned LVM volumes, assigned pci and usb devices, setting up 
the bridge, large pages, guest priorities).  Why are we adding code to 
benefit so few people, many of whom don't really use qemu as users?

-- 
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