Messages in this thread Patch in this message | | | From | Jiri Slaby <> | Subject | [PATCH 3.12 087/103] mactap: Fix checksum errors for non-gso packets in bridge mode | Date | Thu, 29 May 2014 15:49:12 +0200 |
| |
From: Vlad Yasevich <vyasevic@redhat.com>
3.12-stable review patch. If anyone has any objections, please let me know.
===============
[ Upstream commit cbdb04279ccaefcc702c8757757eea8ed76e50cf ]
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 <daniel.lezcano@free.fr> CC: Patrick McHardy <kaber@trash.net> CC: Andrian Nord <nightnord@gmail.com> CC: Eric Dumazet <eric.dumazet@gmail.com> CC: Michael S. Tsirkin <mst@redhat.com> CC: Jason Wang <jasowang@redhat.com> Signed-off-by: Vlad Yasevich <vyasevic@redhat.com> Acked-by: Jason Wang <jasowang@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Jiri Slaby <jslaby@suse.cz> --- drivers/net/macvtap.c | 9 +++++++++ 1 file changed, 9 insertions(+)
diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c index 5895e4dbbf2a..d0f165f2877b 100644 --- a/drivers/net/macvtap.c +++ b/drivers/net/macvtap.c @@ -315,6 +315,15 @@ static int macvtap_forward(struct net_device *dev, struct sk_buff *skb) segs = nskb; } } else { + /* If we receive a partial checksum and the tap side + * doesn't support checksum offload, compute the checksum. + * Note: it doesn't matter which checksum feature to + * check, we either support them all or none. + */ + if (skb->ip_summed == CHECKSUM_PARTIAL && + !(features & NETIF_F_ALL_CSUM) && + skb_checksum_help(skb)) + goto drop; skb_queue_tail(&q->sk.sk_receive_queue, skb); } -- 1.9.3
| |