datapath-windows: Merge split dis-continuous net-buf.

NdisGetDataBuffer() is called without providing a buffer to copy packet
data in case it is not contiguous.  So, it fails in some scenarios
where the packet is handled by the general network stack before OVS
and headers become split in multiple buffers.

In the fix it will supply the stack buffer to copy packet data when
call NdisGetDataBuffer().

In the conntrack Action process, it will do OvsPartialCopyNBL firstly
with the size of layers l7offsets. If the header is split the header
will be merged to one continuous buffer.

But IPV6 traffic is not handed in this patch to merge the split
dis-continuous net-buf.
Reported-at: openvswitch/ovs-issues#323

Signed-off-by: Wilson Peng <pweisong@vmware.com>
Signed-off-by: 0-day Robot <robot@bytheb.org>

Author: pweisong

datapath-windows/ovsext/Actions.c

@@ -2414,6 +2414,14 @@ OvsDoExecuteActions(POVS_SWITCH_CONTEXT switchContext,
             }
 
             PNET_BUFFER_LIST oldNbl = ovsFwdCtx.curNbl;
+            if (layers->value != 0 && layers->isIPv4 && layers->l7Offset != 0) {
+                PUINT8 bufferStart = NULL;
+                bufferStart = OvsGetHeaderBySize(&ovsFwdCtx, layers->l7Offset);
+                if (!bufferStart) {
+                    dropReason = L"OVS-Netbuf reallocated failed";
+                    goto dropit;
+                }
+            }
             status = OvsExecuteConntrackAction(&ovsFwdCtx, key,
                                                (const PNL_ATTR)a);
             if (status != NDIS_STATUS_SUCCESS) {

datapath-windows/ovsext/BufferMgmt.c

@@ -1106,24 +1106,24 @@ GetIpHeaderInfo(PNET_BUFFER_LIST curNbl,
                 const POVS_PACKET_HDR_INFO hdrInfo,
                 UINT32 *hdrSize)
 {
-    EthHdr *eth;
-    IPHdr *ipHdr;
-    IPv6Hdr *ipv6Hdr;
-    PNET_BUFFER curNb;
-
-    curNb = NET_BUFFER_LIST_FIRST_NB(curNbl);
-    ASSERT(NET_BUFFER_NEXT_NB(curNb) == NULL);
-    eth = (EthHdr *)NdisGetDataBuffer(curNb,
-                                      hdrInfo->l4Offset,
-                                      NULL, 1, 0);
-    if (eth == NULL) {
-        return NDIS_STATUS_INVALID_PACKET;
-    }
-
     if (hdrInfo->isIPv6) {
-        ipv6Hdr = (IPv6Hdr *)((PCHAR)eth + hdrInfo->l3Offset);
         *hdrSize = (UINT32)(hdrInfo->l4Offset);
     } else {
+        EthHdr *eth;
+        IPHdr *ipHdr;
+        CHAR tempBuf[MAX_IPV4_PKT_HDR_LEN];
+        PNET_BUFFER curNb;
+
+        curNb = NET_BUFFER_LIST_FIRST_NB(curNbl);
+        ASSERT(NET_BUFFER_NEXT_NB(curNb) == NULL);
+
+        NdisZeroMemory(tempBuf, MAX_IPV4_PKT_HDR_LEN);
+        eth = (EthHdr *)NdisGetDataBuffer(curNb,
+                                          hdrInfo->l4Offset,
+                                          (PVOID)tempBuf, 1, 0);
+        if (eth == NULL) {
+           return NDIS_STATUS_INVALID_PACKET;
+        }
         ipHdr = (IPHdr *)((PCHAR)eth + hdrInfo->l3Offset);
         *hdrSize = (UINT32)(hdrInfo->l3Offset + (ipHdr->ihl * 4));
     }

datapath-windows/ovsext/Conntrack.c

@@ -683,6 +683,7 @@ OvsGetTcpHeader(PNET_BUFFER_LIST nbl,
     TCPHdr *tcp;
     VOID *dest = storage;
     uint16_t ipv6ExtLength = 0;
+    CHAR tempBuf[MAX_IPV4_PKT_HDR_LEN];
 
     if (layers->isIPv6) {
         ipv6Hdr = NdisGetDataBuffer(NET_BUFFER_LIST_FIRST_NB(nbl),
@@ -701,9 +702,10 @@ OvsGetTcpHeader(PNET_BUFFER_LIST nbl,
             return storage;
         }
     } else {
+        NdisZeroMemory(tempBuf, MAX_IPV4_PKT_HDR_LEN);
         ipHdr = NdisGetDataBuffer(NET_BUFFER_LIST_FIRST_NB(nbl),
                                   layers->l4Offset + sizeof(TCPHdr),
-                                  NULL, 1 /*no align*/, 0);
+                                  (PVOID)tempBuf, 1 /*no align*/, 0);
         if (ipHdr == NULL) {
             return NULL;
         }

datapath-windows/ovsext/IpFragment.c

@@ -153,12 +153,14 @@ OvsIpv4Reassemble(POVS_SWITCH_CONTEXT switchContext,
     PNET_BUFFER_LIST newNbl = NULL;
     UINT16 ipHdrLen, packetHeader;
     UINT32 packetLen;
+    CHAR tempBuf[MAX_IPV4_PKT_HDR_LEN];
 
     curNb = NET_BUFFER_LIST_FIRST_NB(*curNbl);
     ASSERT(NET_BUFFER_NEXT_NB(curNb) == NULL);
 
+    NdisZeroMemory(tempBuf, MAX_IPV4_PKT_HDR_LEN);
     eth = (EthHdr*)NdisGetDataBuffer(curNb, layers->l4Offset,
-                                     NULL, 1, 0);
+                                     (PVOID)tempBuf, 1, 0);
     if (eth == NULL) {
         return NDIS_STATUS_INVALID_PACKET;
     }
@@ -253,12 +255,14 @@ OvsProcessIpv4Fragment(POVS_SWITCH_CONTEXT switchContext,
     POVS_IPFRAG_ENTRY entry;
     POVS_FRAGMENT_LIST fragStorage;
     LOCK_STATE_EX htLockState;
+    CHAR tempBuf[MAX_IPV4_PKT_HDR_LEN];
 
     curNb = NET_BUFFER_LIST_FIRST_NB(*curNbl);
     ASSERT(NET_BUFFER_NEXT_NB(curNb) == NULL);
 
+    NdisZeroMemory(tempBuf, MAX_IPV4_PKT_HDR_LEN);
     eth = (EthHdr*)NdisGetDataBuffer(curNb, layers->l4Offset,
-                                     NULL, 1, 0);
+                                     (PVOID)tempBuf, 1, 0);
     if (eth == NULL) {
         return NDIS_STATUS_INVALID_PACKET;
     }

datapath-windows/ovsext/PacketParser.h

@@ -18,6 +18,7 @@
 #define __PACKET_PARSER_H_ 1
 
 #define MIN_IPV4_HLEN 20
+#define MAX_IPV4_PKT_HDR_LEN (ETH_MAX_HEADER_LEN + MAX_IPV4_HLEN)
 
 #include "precomp.h"
 #include "NetProto.h"