On 01/26/2010 05:15 PM, Sridhar Samudrala wrote:
On Tue, 2010-01-26 at 14:47 -0600, Anthony Liguori wrote:
On 01/26/2010 02:40 PM, Sridhar Samudrala wrote:
This patch adds raw socket backend to qemu and is based on Or Gerlitz's
patch re-factored and ported to the latest qemu-kvm git tree.
It also includes support for vnet_hdr option that enables gso/checksum
offload with raw backend. You can find the linux kernel patch to support
this feature here.
http://thread.gmane.org/gmane.linux.network/150308
Signed-off-by: Sridhar Samudrala<sri@xxxxxxxxxx>
See the previous discussion about the raw backend from Or's original
patch. There's no obvious reason why we should have this in addition to
a tun/tap backend.
The only use-case I know of is macvlan but macvtap addresses this
functionality while not introduce the rather nasty security problems
associated with a raw backend.
The raw backend can be attached to a physical device
This is equivalent to bridging with tun/tap except that it has the
unexpected behaviour of unreliable host/guest networking (which is not
universally consistent across platforms either). This is not a mode we
want to encourage users to use.
, macvlan
macvtap is a superior way to achieve this use case because a macvtap fd
can safely be given to a lesser privilege process without allowing
escalation of privileges.
or SR-IOV VF.
This depends on vhost-net. In general, what I would like to see for
this is something more user friendly that dealt specifically with this
use-case. Although honestly, given the recent security concerns around
raw sockets, I'm very concerned about supporting raw sockets in qemu at all.
Essentially, you get worse security doing vhost-net + raw + VF then with
PCI passthrough + VF because at least in the later case you can run qemu
without privileges. CAP_NET_RAW is a very big privilege.
Regards,
Anthony Liguori
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