On 01/27/2010 10:59 AM, Michael S. Tsirkin wrote:
On Wed, Jan 27, 2010 at 08:07:11AM -0600, Anthony Liguori wrote:
On 01/27/2010 03:24 AM, Michael S. Tsirkin wrote:
I am not sure I agree with this sentiment. The main issue being that
macvtap doesn't exist on all kernels :).
Neither does vhost ;-) If it were just that as the difference, I'd be
inclined to agree, but macvtap is much better from a security PoV.
Not to mention that from a user perspective, raw makes almost no sense
as it's an obscure socket protocol family.
A user wants to do useful things like bridged networking or direct VF
assignment. We should have -net backends that reflect things that make
sense to a user.
Regards,
Anthony Liguori
I agree to that. People don't even seem to agree whether it's a raw
socket or a packet socket :) We need a better name for this option: what
it really does is rely on an external device to loopback a packet to us,
so how about -net loopback or -net extbridge?
Specifically for VEPA, something like:
-net extbridge,if=eth0
or even
-net vepa,if=eth0
Would be fantastic.
extbridge is IMO better.
I think the best way to achieve this is to
introduce a small helper that gets called and can create a macvtap
device and hand the file descriptor back to qemu :-) A builtin backend
would also be fine since we don't have the helper infrastructure.
Excellent.
Sridhar, this is actually not a lot of work on top of what you
already posted.
N.B. I had suggested using macvtap, not raw. In this case, the full
syntax would be:
-net vepa,if=eth0
or
-net vepa,fd=N
where N is a macvtap fd.
For raw, I think there's a real problem wrt security. I think it's
important that we support running qemu as a non-privileged user. In
fact, this seems to be the mode libvirt is now preferring to operate in.
I think we need to re-evaluate the use of any raw socket by qemu as it's
very dangerous from a security perspective (assuming we cannot
introduced a "locked" raw socket mode).
Regards,
Anthony Liguori
Regards,
Anthony Liguori
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