[ovs-dev] [PATCH] datapath-windows: Fix conntrack lookups for reversed keys

Anand Kumar kumaranand at vmware.com
Tue Aug 1 22:01:44 UTC 2017


From: Sairam Venugopal <vsairam at vmware.com>

The conntrack table needs to be queried for entries in either directions
to determine if the packet is in forward direction or reply direction.

The current behavior ends up reversing the incoming packet's 5-Tuple for
every entry in the loop instead of doing it only once.

Testing Done:
- Verified that ICMP requests are no longer treated as replies
in Conntrack.

Change-Id: I826a164cfb9137e2167c404ff5c9bfd9dfaa33ad
Co-authored-by: Sairam Venugopal <vsairam at vmware.com>
Signed-off-by: Anand Kumar <kumaranand at vmware.com>
---
 datapath-windows/ovsext/Conntrack.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/datapath-windows/ovsext/Conntrack.c b/datapath-windows/ovsext/Conntrack.c
index 8ea1e65..917ebee 100644
--- a/datapath-windows/ovsext/Conntrack.c
+++ b/datapath-windows/ovsext/Conntrack.c
@@ -401,7 +401,14 @@ OvsCtLookup(OvsConntrackKeyLookupCtx *ctx)
     POVS_CT_ENTRY entry;
     BOOLEAN reply = FALSE;
     POVS_CT_ENTRY found = NULL;
-    OVS_CT_KEY key = ctx->key;
+
+    /* Reverse NAT must be performed before OvsCtLookup, so here
+     * we simply need to flip the src and dst in key and compare
+     * they are equal. Note that flipped key is not equal to
+     * rev_key due to NAT effect.
+     */
+    OVS_CT_KEY revCtxKey = ctx->key;
+    OvsCtKeyReverse(&revCtxKey);
 
     if (!ctTotalEntries) {
         return found;
@@ -410,19 +417,13 @@ OvsCtLookup(OvsConntrackKeyLookupCtx *ctx)
     LIST_FORALL(&ovsConntrackTable[ctx->hash & CT_HASH_TABLE_MASK], link) {
         entry = CONTAINING_RECORD(link, OVS_CT_ENTRY, link);
 
-        if (OvsCtKeyAreSame(key,entry->key)) {
+        if (OvsCtKeyAreSame(ctx->key, entry->key)) {
             found = entry;
             reply = FALSE;
             break;
         }
 
-        /* Reverse NAT must be performed before OvsCtLookup, so here
-         * we simply need to flip the src and dst in key and compare
-         * they are equal. Note that flipped key is not equal to
-         * rev_key due to NAT effect.
-         */
-        OvsCtKeyReverse(&key);
-        if (OvsCtKeyAreSame(key, entry->key)) {
+        if (OvsCtKeyAreSame(revCtxKey, entry->key)) {
             found = entry;
             reply = TRUE;
             break;
-- 
2.9.3.windows.1



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