[ovs-dev] [PATCH v2 1/1] datapath-windows: Reset flow key after Ipv4 fragments are reassembled

Wilson Peng pweisong at vmware.com
Tue Nov 9 15:55:27 UTC 2021


While testing OVS-windows flows for the Ip fragments, the traffic will be dropped
As it may match incorrect OVS flow.  From the code, after the Ipv4 fragments are
Reassembled, it willl still use the flow key of the last Ipv4 fragments to match
CT causing match error.

Reported-at:https://github.com/openvswitch/ovs-issues/issues/232
Signed-off-by: Wilson Peng <pweisong at vmware.com>
---
 datapath-windows/ovsext/Conntrack.c | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/datapath-windows/ovsext/Conntrack.c b/datapath-windows/ovsext/Conntrack.c
index 2610d626a..3b2b5fd32 100644
--- a/datapath-windows/ovsext/Conntrack.c
+++ b/datapath-windows/ovsext/Conntrack.c
@@ -493,15 +493,32 @@ static __inline NDIS_STATUS
 OvsDetectCtPacket(OvsForwardingContext *fwdCtx,
                   OvsFlowKey *key)
 {
+    NDIS_STATUS status = NDIS_STATUS_SUCCESS;
+    OvsFlowKey  newFlowKey = { 0 };
+
     switch (ntohs(key->l2.dlType)) {
     case ETH_TYPE_IPV4:
         if (key->ipKey.nwFrag != OVS_FRAG_TYPE_NONE) {
-            return OvsProcessIpv4Fragment(fwdCtx->switchContext,
+            status = OvsProcessIpv4Fragment(fwdCtx->switchContext,
                                           &fwdCtx->curNbl,
                                           fwdCtx->completionList,
                                           fwdCtx->fwdDetail->SourcePortId,
                                           &fwdCtx->layers,
                                           key->tunKey.tunnelId);
+            if (status == NDIS_STATUS_SUCCESS) {
+                 /*after the Ipv4 Fragment is reassembled, update flow key as 
+                   L3 and L4 headers are not correct */
+                 status =
+                      OvsExtractFlow(fwdCtx->curNbl, fwdCtx->srcVportNo,
+                                     &newFlowKey, &fwdCtx->layers,
+                                     fwdCtx->tunKey.dst != 0 ? &fwdCtx->tunKey : NULL);
+                if (status != NDIS_STATUS_SUCCESS) {
+                     OVS_LOG_ERROR("Extract flow failed Nbl %p", fwdCtx->curNbl);
+                     return status;
+                 }
+                *key = newFlowKey;
+            }
+            return status;
         }
         if (key->ipKey.nwProto == IPPROTO_TCP
             || key->ipKey.nwProto == IPPROTO_UDP
-- 
2.24.3 (Apple Git-128)



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