mactap: Fix checksum errors for non-gso packets in bridge mode

The following is a problematic configuration:

 VM1: virtio-net device connected to macvtap0@eth0
 VM2: e1000 device connect to macvtap1@eth0

The problem is is that virtio-net supports checksum offloading
and thus sends the packets to the host with CHECKSUM_PARTIAL set.
On the other hand, e1000 does not support any acceleration.

For small TCP packets (and this includes the 3-way handshake),
e1000 ends up receiving packets that only have a partial checksum
set.  This causes TCP to fail checksum validation and to drop
packets.  As a result tcp connections can not be established.

Commit 3e4f8b787370978733ca6cae452720a4f0c296b8
	macvtap: Perform GSO on forwarding path.
fixes this issue for large packets wthat will end up undergoing GSO.
This commit adds a check for the non-GSO case and attempts to
compute the checksum for partially checksummed packets in the
non-GSO case.

CC: Daniel Lezcano <[email protected]>
CC: Patrick McHardy <[email protected]>
CC: Andrian Nord <[email protected]>
CC: Eric Dumazet <[email protected]>
CC: Michael S. Tsirkin <[email protected]>
CC: Jason Wang <[email protected]>
Signed-off-by: Vlad Yasevich <[email protected]>
Acked-by: Jason Wang <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

0 files changed, 0 insertions, 0 deletions