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[ovs-dev,ovs-dev,v1,1/1] datapath-windows:adjust Offset when processing packet in POP_VLAN action

Message ID 20210927142719.20961-1-pweisong@vmware.com
State Changes Requested
Delegated to: Alin Gabriel Serdean
Headers show
Series [ovs-dev,ovs-dev,v1,1/1] datapath-windows:adjust Offset when processing packet in POP_VLAN action | expand

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ovsrobot/apply-robot success apply and check: success
ovsrobot/github-robot-_Build_and_Test fail github build: failed

Commit Message

Wilson Peng Sept. 27, 2021, 2:27 p.m. UTC 
In one typical setup, on the Windows VM running OVS Windows Kernel, a Geneva
packet with 8021.q VLAN tag is received. Then it may do POP_VLAN action
processing in Actions.c, if the packet does not have Ieee8021QNetBufferListInfo
in the oob of the packet, it will be processed by function OvsPopVlanInPktBuf().
In the function it will go on remove VLAN header present in the nbl, but related
layers is never readjusted for the offset value at this moment. As a result, it
will cause function OvsValidateIPChecksum drop the packet.

Reported-at:https://github.com/openvswitch/ovs-issues/issues/225
Signed-off-by: wilsonpeng <pweisong@vmware.com>
---
 datapath-windows/ovsext/Actions.c | 7 +++++++
 1 file changed, 7 insertions(+)

Comments

Alin-Gabriel Serdean Sept. 29, 2021, 1:54 p.m. UTC | #1 
From: aserdean@ovn.org

Thank you for raising awareness about this issue. You are right the
offsets are not being updated when a pop vlan action is hit, they are
updated only on pop_mpls.
https://github.com/openvswitch/ovs/blob/master/datapath-windows/ovsext/Actions.c#L1173-L1174
Can you please update the offsets in the corresponding pop vlan
function. I.e.:
---
 datapath-windows/ovsext/Actions.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/datapath-windows/ovsext/Actions.c b/datapath-windows/ovsext/Actions.c
index e130c2f96..34aa5c5e4 100644
--- a/datapath-windows/ovsext/Actions.c
+++ b/datapath-windows/ovsext/Actions.c
@@ -1141,11 +1141,21 @@ OvsPopVlanInPktBuf(OvsForwardingContext *ovsFwdCtx)
      * Declare a dummy vlanTag structure since we need to compute the size
      * of shiftLength. The NDIS one is a unionized structure.
      */
+    NDIS_STATUS status;
+    OVS_PACKET_HDR_INFO* layers = &ovsFwdCtx->layers;
     NDIS_PACKET_8021Q_INFO vlanTag = {0};
     UINT32 shiftLength = sizeof(vlanTag.TagHeader);
     UINT32 shiftOffset = sizeof(DL_EUI48) + sizeof(DL_EUI48);
 
-    return OvsPopFieldInPacketBuf(ovsFwdCtx, shiftOffset, shiftLength, NULL);
+    status = OvsPopFieldInPacketBuf(ovsFwdCtx, shiftOffset, shiftLength,
+                                    NULL);
+
+    if (status == NDIS_STATUS_SUCCESS) {
+        layers->l3Offset -= (UINT16) shiftLength;
+        layers->l4Offset -= (UINT16) shiftLength;
+    }
+
+    return status;
 }
Wilson Peng Sept. 29, 2021, 2:52 p.m. UTC | #2 
Alin,

Original code diff is to avoid the case below(it will return NDIS_STATUS_SUCCESS before 
RtlMoveMemory in function OvsPopFieldInPacketBuf).

Regards
Wilson

In function OvsPopFieldInPacketBuf(..)
 if (!bufferData) {
        EthHdr *ethHdr = (EthHdr *)bufferStart;
        /* If the frame is not VLAN make it a no op */
        if (ethHdr->Type != ETH_TYPE_802_1PQ_NBO) {
            return NDIS_STATUS_SUCCESS;        ---->  may exit here.
        }
    }

  RtlMoveMemory(bufferStart + shiftLength, bufferStart, shiftOffset);
  NdisAdvanceNetBufferDataStart(curNb, shiftLength, FALSE, NULL);

在 2021/9/29 21:55，“dev 代表 Alin-Gabriel Serdean”<ovs-dev-bounces@openvswitch.org 代表 aserdean@ovn.org> 写入:

    From: aserdean@ovn.org

    Thank you for raising awareness about this issue. You are right the
    offsets are not being updated when a pop vlan action is hit, they are
    updated only on pop_mpls.
    https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fopenvswitch%2Fovs%2Fblob%2Fmaster%2Fdatapath-windows%2Fovsext%2FActions.c%23L1173-L1174&amp;data=04%7C01%7Cpweisong%40vmware.com%7C97a24c5e1c5642cde59d08d98350cbed%7Cb39138ca3cee4b4aa4d6cd83d9dd62f0%7C0%7C0%7C637685205333861058%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=J4d0vndzCmjpdacwp5KBVntxzNsWepJkSxqvEPRTbCQ%3D&amp;reserved=0
    Can you please update the offsets in the corresponding pop vlan
    function. I.e.:
    ---
     datapath-windows/ovsext/Actions.c | 12 +++++++++++-
     1 file changed, 11 insertions(+), 1 deletion(-)

    diff --git a/datapath-windows/ovsext/Actions.c b/datapath-windows/ovsext/Actions.c
    index e130c2f96..34aa5c5e4 100644
    --- a/datapath-windows/ovsext/Actions.c
    +++ b/datapath-windows/ovsext/Actions.c
    @@ -1141,11 +1141,21 @@ OvsPopVlanInPktBuf(OvsForwardingContext *ovsFwdCtx)
          * Declare a dummy vlanTag structure since we need to compute the size
          * of shiftLength. The NDIS one is a unionized structure.
          */
    +    NDIS_STATUS status;
    +    OVS_PACKET_HDR_INFO* layers = &ovsFwdCtx->layers;
         NDIS_PACKET_8021Q_INFO vlanTag = {0};
         UINT32 shiftLength = sizeof(vlanTag.TagHeader);
         UINT32 shiftOffset = sizeof(DL_EUI48) + sizeof(DL_EUI48);

    -    return OvsPopFieldInPacketBuf(ovsFwdCtx, shiftOffset, shiftLength, NULL);
    +    status = OvsPopFieldInPacketBuf(ovsFwdCtx, shiftOffset, shiftLength,
    +                                    NULL);
    +
    +    if (status == NDIS_STATUS_SUCCESS) {
    +        layers->l3Offset -= (UINT16) shiftLength;
    +        layers->l4Offset -= (UINT16) shiftLength;
    +    }
    +
    +    return status;
     }


    -- 
    2.32.0

    _______________________________________________
    dev mailing list
    dev@openvswitch.org
    https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fmail.openvswitch.org%2Fmailman%2Flistinfo%2Fovs-dev&amp;data=04%7C01%7Cpweisong%40vmware.com%7C97a24c5e1c5642cde59d08d98350cbed%7Cb39138ca3cee4b4aa4d6cd83d9dd62f0%7C0%7C0%7C637685205333861058%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=cYplthGDj6Y3JKU33UWegukyXDh7ZehNv6wXVqfWD6s%3D&amp;reserved=0
Alin-Gabriel Serdean Sept. 29, 2021, 3:21 p.m. UTC | #3 
Indeed. Thanks for pointing that out.

To be honest that looks like a bug.
We should return an error if the it is not a valid VLAN frame.

-----Original Message-----
From: Wilson Peng <pweisong@vmware.com> 
Sent: Wednesday, September 29, 2021 5:52 PM
To: Alin-Gabriel Serdean <aserdean@ovn.org>; ovs-dev@openvswitch.org
Subject: Re: [ovs-dev] [PATCH] datapath-windows:adjust Offset when processing packet in POP_VLAN action

Alin,

Original code diff is to avoid the case below(it will return NDIS_STATUS_SUCCESS before RtlMoveMemory in function OvsPopFieldInPacketBuf).

Regards
Wilson

In function OvsPopFieldInPacketBuf(..)
 if (!bufferData) {
        EthHdr *ethHdr = (EthHdr *)bufferStart;
        /* If the frame is not VLAN make it a no op */
        if (ethHdr->Type != ETH_TYPE_802_1PQ_NBO) {
            return NDIS_STATUS_SUCCESS;        ---->  may exit here.
        }
    }

  RtlMoveMemory(bufferStart + shiftLength, bufferStart, shiftOffset);
  NdisAdvanceNetBufferDataStart(curNb, shiftLength, FALSE, NULL);

在 2021/9/29 21:55，“dev 代表 Alin-Gabriel Serdean”<ovs-dev-bounces@openvswitch.org 代表 aserdean@ovn.org> 写入:

    From: aserdean@ovn.org

    Thank you for raising awareness about this issue. You are right the
    offsets are not being updated when a pop vlan action is hit, they are
    updated only on pop_mpls.
    https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fopenvswitch%2Fovs%2Fblob%2Fmaster%2Fdatapath-windows%2Fovsext%2FActions.c%23L1173-L1174&amp;data=04%7C01%7Cpweisong%40vmware.com%7C97a24c5e1c5642cde59d08d98350cbed%7Cb39138ca3cee4b4aa4d6cd83d9dd62f0%7C0%7C0%7C637685205333861058%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=J4d0vndzCmjpdacwp5KBVntxzNsWepJkSxqvEPRTbCQ%3D&amp;reserved=0
    Can you please update the offsets in the corresponding pop vlan
    function. I.e.:
    ---
     datapath-windows/ovsext/Actions.c | 12 +++++++++++-
     1 file changed, 11 insertions(+), 1 deletion(-)

    diff --git a/datapath-windows/ovsext/Actions.c b/datapath-windows/ovsext/Actions.c
    index e130c2f96..34aa5c5e4 100644
    --- a/datapath-windows/ovsext/Actions.c
    +++ b/datapath-windows/ovsext/Actions.c
    @@ -1141,11 +1141,21 @@ OvsPopVlanInPktBuf(OvsForwardingContext *ovsFwdCtx)
          * Declare a dummy vlanTag structure since we need to compute the size
          * of shiftLength. The NDIS one is a unionized structure.
          */
    +    NDIS_STATUS status;
    +    OVS_PACKET_HDR_INFO* layers = &ovsFwdCtx->layers;
         NDIS_PACKET_8021Q_INFO vlanTag = {0};
         UINT32 shiftLength = sizeof(vlanTag.TagHeader);
         UINT32 shiftOffset = sizeof(DL_EUI48) + sizeof(DL_EUI48);

    -    return OvsPopFieldInPacketBuf(ovsFwdCtx, shiftOffset, shiftLength, NULL);
    +    status = OvsPopFieldInPacketBuf(ovsFwdCtx, shiftOffset, shiftLength,
    +                                    NULL);
    +
    +    if (status == NDIS_STATUS_SUCCESS) {
    +        layers->l3Offset -= (UINT16) shiftLength;
    +        layers->l4Offset -= (UINT16) shiftLength;
    +    }
    +
    +    return status;
     }


    -- 
    2.32.0

    _______________________________________________
    dev mailing list
    dev@openvswitch.org
    https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fmail.openvswitch.org%2Fmailman%2Flistinfo%2Fovs-dev&amp;data=04%7C01%7Cpweisong%40vmware.com%7C97a24c5e1c5642cde59d08d98350cbed%7Cb39138ca3cee4b4aa4d6cd83d9dd62f0%7C0%7C0%7C637685205333861058%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=cYplthGDj6Y3JKU33UWegukyXDh7ZehNv6wXVqfWD6s%3D&amp;reserved=0
Wilson Peng Sept. 30, 2021, 5:01 a.m. UTC | #4 
Alin,

Thanks for your comments, I have sent out the updated patch, please help check.
https://patchwork.ozlabs.org/project/openvswitch/patch/20210930045626.9250-1-pweisong@vmware.com/

Regards
Wilson

在 2021/9/29 23:21，“Alin-Gabriel Serdean”<aserdean@ovn.org> 写入:

    Indeed. Thanks for pointing that out.

    To be honest that looks like a bug.
    We should return an error if the it is not a valid VLAN frame.

    -----Original Message-----
    From: Wilson Peng <pweisong@vmware.com> 
    Sent: Wednesday, September 29, 2021 5:52 PM
    To: Alin-Gabriel Serdean <aserdean@ovn.org>; ovs-dev@openvswitch.org
    Subject: Re: [ovs-dev] [PATCH] datapath-windows:adjust Offset when processing packet in POP_VLAN action

    Alin,

    Original code diff is to avoid the case below(it will return NDIS_STATUS_SUCCESS before RtlMoveMemory in function OvsPopFieldInPacketBuf).

    Regards
    Wilson

    In function OvsPopFieldInPacketBuf(..)
     if (!bufferData) {
            EthHdr *ethHdr = (EthHdr *)bufferStart;
            /* If the frame is not VLAN make it a no op */
            if (ethHdr->Type != ETH_TYPE_802_1PQ_NBO) {
                return NDIS_STATUS_SUCCESS;        ---->  may exit here.
            }
        }

      RtlMoveMemory(bufferStart + shiftLength, bufferStart, shiftOffset);
      NdisAdvanceNetBufferDataStart(curNb, shiftLength, FALSE, NULL);

    在 2021/9/29 21:55，“dev 代表 Alin-Gabriel Serdean”<ovs-dev-bounces@openvswitch.org 代表 aserdean@ovn.org> 写入:

        From: aserdean@ovn.org

        Thank you for raising awareness about this issue. You are right the
        offsets are not being updated when a pop vlan action is hit, they are
        updated only on pop_mpls.
        https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fopenvswitch%2Fovs%2Fblob%2Fmaster%2Fdatapath-windows%2Fovsext%2FActions.c%23L1173-L1174&amp;data=04%7C01%7Cpweisong%40vmware.com%7Ca65191ed9abd47b21a8608d9835cddfe%7Cb39138ca3cee4b4aa4d6cd83d9dd62f0%7C0%7C0%7C637685257162775283%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=oonWmImrDVicJ%2BBdGaYvmNDiUsueMXwOOjSn9MuFmBE%3D&amp;reserved=0
        Can you please update the offsets in the corresponding pop vlan
        function. I.e.:
        ---
         datapath-windows/ovsext/Actions.c | 12 +++++++++++-
         1 file changed, 11 insertions(+), 1 deletion(-)

        diff --git a/datapath-windows/ovsext/Actions.c b/datapath-windows/ovsext/Actions.c
        index e130c2f96..34aa5c5e4 100644
        --- a/datapath-windows/ovsext/Actions.c
        +++ b/datapath-windows/ovsext/Actions.c
        @@ -1141,11 +1141,21 @@ OvsPopVlanInPktBuf(OvsForwardingContext *ovsFwdCtx)
              * Declare a dummy vlanTag structure since we need to compute the size
              * of shiftLength. The NDIS one is a unionized structure.
              */
        +    NDIS_STATUS status;
        +    OVS_PACKET_HDR_INFO* layers = &ovsFwdCtx->layers;
             NDIS_PACKET_8021Q_INFO vlanTag = {0};
             UINT32 shiftLength = sizeof(vlanTag.TagHeader);
             UINT32 shiftOffset = sizeof(DL_EUI48) + sizeof(DL_EUI48);

        -    return OvsPopFieldInPacketBuf(ovsFwdCtx, shiftOffset, shiftLength, NULL);
        +    status = OvsPopFieldInPacketBuf(ovsFwdCtx, shiftOffset, shiftLength,
        +                                    NULL);
        +
        +    if (status == NDIS_STATUS_SUCCESS) {
        +        layers->l3Offset -= (UINT16) shiftLength;
        +        layers->l4Offset -= (UINT16) shiftLength;
        +    }
        +
        +    return status;
         }


        -- 
        2.32.0

        _______________________________________________
        dev mailing list
        dev@openvswitch.org
        https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fmail.openvswitch.org%2Fmailman%2Flistinfo%2Fovs-dev&amp;data=04%7C01%7Cpweisong%40vmware.com%7Ca65191ed9abd47b21a8608d9835cddfe%7Cb39138ca3cee4b4aa4d6cd83d9dd62f0%7C0%7C0%7C637685257162775283%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=29gFWHNVRPTixEkYAQeD6HevknOxi6%2BYerYFAUM3FTI%3D&amp;reserved=0
Alin Serdean Sept. 30, 2021, 7:02 a.m. UTC | #5 
Thank you for addressing the comments I applied the incremental version and backported it until 2.7.

Thank you,
Alin.

-----Original Message-----
From: Wilson Peng <pweisong@vmware.com> 
Sent: Thursday, September 30, 2021 8:02 AM
To: Alin-Gabriel Serdean <aserdean@ovn.org>; ovs-dev@openvswitch.org
Subject: Re: [ovs-dev] [PATCH] datapath-windows:adjust Offset when processing packet in POP_VLAN action

Alin,

Thanks for your comments, I have sent out the updated patch, please help check.
https://patchwork.ozlabs.org/project/openvswitch/patch/20210930045626.9250-1-pweisong@vmware.com/

Regards
Wilson

在 2021/9/29 23:21，“Alin-Gabriel Serdean”<aserdean@ovn.org> 写入:

    Indeed. Thanks for pointing that out.

    To be honest that looks like a bug.
    We should return an error if the it is not a valid VLAN frame.

    -----Original Message-----
    From: Wilson Peng <pweisong@vmware.com> 
    Sent: Wednesday, September 29, 2021 5:52 PM
    To: Alin-Gabriel Serdean <aserdean@ovn.org>; ovs-dev@openvswitch.org
    Subject: Re: [ovs-dev] [PATCH] datapath-windows:adjust Offset when processing packet in POP_VLAN action

    Alin,

    Original code diff is to avoid the case below(it will return NDIS_STATUS_SUCCESS before RtlMoveMemory in function OvsPopFieldInPacketBuf).

    Regards
    Wilson

    In function OvsPopFieldInPacketBuf(..)
     if (!bufferData) {
            EthHdr *ethHdr = (EthHdr *)bufferStart;
            /* If the frame is not VLAN make it a no op */
            if (ethHdr->Type != ETH_TYPE_802_1PQ_NBO) {
                return NDIS_STATUS_SUCCESS;        ---->  may exit here.
            }
        }

      RtlMoveMemory(bufferStart + shiftLength, bufferStart, shiftOffset);
      NdisAdvanceNetBufferDataStart(curNb, shiftLength, FALSE, NULL);

    在 2021/9/29 21:55，“dev 代表 Alin-Gabriel Serdean”<ovs-dev-bounces@openvswitch.org 代表 aserdean@ovn.org> 写入:

        From: aserdean@ovn.org

        Thank you for raising awareness about this issue. You are right the
        offsets are not being updated when a pop vlan action is hit, they are
        updated only on pop_mpls.
        https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fopenvswitch%2Fovs%2Fblob%2Fmaster%2Fdatapath-windows%2Fovsext%2FActions.c%23L1173-L1174&amp;data=04%7C01%7Cpweisong%40vmware.com%7Ca65191ed9abd47b21a8608d9835cddfe%7Cb39138ca3cee4b4aa4d6cd83d9dd62f0%7C0%7C0%7C637685257162775283%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=oonWmImrDVicJ%2BBdGaYvmNDiUsueMXwOOjSn9MuFmBE%3D&amp;reserved=0
        Can you please update the offsets in the corresponding pop vlan
        function. I.e.:
        ---
         datapath-windows/ovsext/Actions.c | 12 +++++++++++-
         1 file changed, 11 insertions(+), 1 deletion(-)

        diff --git a/datapath-windows/ovsext/Actions.c b/datapath-windows/ovsext/Actions.c
        index e130c2f96..34aa5c5e4 100644
        --- a/datapath-windows/ovsext/Actions.c
        +++ b/datapath-windows/ovsext/Actions.c
        @@ -1141,11 +1141,21 @@ OvsPopVlanInPktBuf(OvsForwardingContext *ovsFwdCtx)
              * Declare a dummy vlanTag structure since we need to compute the size
              * of shiftLength. The NDIS one is a unionized structure.
              */
        +    NDIS_STATUS status;
        +    OVS_PACKET_HDR_INFO* layers = &ovsFwdCtx->layers;
             NDIS_PACKET_8021Q_INFO vlanTag = {0};
             UINT32 shiftLength = sizeof(vlanTag.TagHeader);
             UINT32 shiftOffset = sizeof(DL_EUI48) + sizeof(DL_EUI48);

        -    return OvsPopFieldInPacketBuf(ovsFwdCtx, shiftOffset, shiftLength, NULL);
        +    status = OvsPopFieldInPacketBuf(ovsFwdCtx, shiftOffset, shiftLength,
        +                                    NULL);
        +
        +    if (status == NDIS_STATUS_SUCCESS) {
        +        layers->l3Offset -= (UINT16) shiftLength;
        +        layers->l4Offset -= (UINT16) shiftLength;
        +    }
        +
        +    return status;
         }


        -- 
        2.32.0

        _______________________________________________
        dev mailing list
        dev@openvswitch.org
        https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fmail.openvswitch.org%2Fmailman%2Flistinfo%2Fovs-dev&amp;data=04%7C01%7Cpweisong%40vmware.com%7Ca65191ed9abd47b21a8608d9835cddfe%7Cb39138ca3cee4b4aa4d6cd83d9dd62f0%7C0%7C0%7C637685257162775283%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=29gFWHNVRPTixEkYAQeD6HevknOxi6%2BYerYFAUM3FTI%3D&amp;reserved=0
diff mbox series

Patch

diff --git a/datapath-windows/ovsext/Actions.c b/datapath-windows/ovsext/Actions.c
index e130c2f96..a9e486752 100644
--- a/datapath-windows/ovsext/Actions.c
+++ b/datapath-windows/ovsext/Actions.c
@@ -1122,6 +1122,13 @@  OvsPopFieldInPacketBuf(OvsForwardingContext *ovsFwdCtx,
 
     if (bufferData) {
         *bufferData = bufferStart + shiftLength;
+    } else {
+        /* Currently !bufferData means it should be treated as VLAN;
+         * Adjust layers Offset value as the vlan tag is removed
+         */
+        OVS_PACKET_HDR_INFO *layers = &ovsFwdCtx->layers;
+        layers->l3Offset -= (UINT16)shiftLength;
+        layers->l4Offset -= (UINT16)shiftLength;
     }
 
     return NDIS_STATUS_SUCCESS;