Eric Lee / smarc-fsl-linux-kernel

16 Sep, 2016

1 commit

  • 86da71b57   net_sched: Introduce skbmod action ... Browse Code ยป

    This action is intended to be an upgrade from a usability perspective
    from pedit (as well as operational debugability).
    Compare this:

    sudo tc filter add dev $ETH parent 1: protocol ip prio 10 \
    u32 match ip protocol 1 0xff flowid 1:2 \
    action pedit munge offset -14 u8 set 0x02 \
    munge offset -13 u8 set 0x15 \
    munge offset -12 u8 set 0x15 \
    munge offset -11 u8 set 0x15 \
    munge offset -10 u16 set 0x1515 \
    pipe

    to:

    sudo tc filter add dev $ETH parent 1: protocol ip prio 10 \
    u32 match ip protocol 1 0xff flowid 1:2 \
    action skbmod dmac 02:15:15:15:15:15

    Also try to do a MAC address swap with pedit or worse
    try to debug a policy with destination mac, source mac and
    etherype. Then make few rules out of those and you'll get my point.

    In the future common use cases on pedit can be migrated to this action
    (as an example different fields in ip v4/6, transports like tcp/udp/sctp
    etc). For this first cut, this allows modifying basic ethernet header.

    The most important ethernet use case at the moment is when redirecting or
    mirroring packets to a remote machine. The dst mac address needs a re-write
    so that it doesnt get dropped or confuse an interconnecting (learning) switch
    or dropped by a target machine (which looks at the dst mac). And at times
    when flipping back the packet a swap of the MAC addresses is needed.

    Signed-off-by: Jamal Hadi Salim
    Signed-off-by: David S. Miller

    Jamal Hadi Salim