• Jesse Gross's avatar
    tunnels: Don't apply GRO to multiple layers of encapsulation. · 23cca87f
    Jesse Gross authored
    commit fac8e0f5 upstream.
    
    When drivers express support for TSO of encapsulated packets, they
    only mean that they can do it for one layer of encapsulation.
    Supporting additional levels would mean updating, at a minimum,
    more IP length fields and they are unaware of this.
    
    No encapsulation device expresses support for handling offloaded
    encapsulated packets, so we won't generate these types of frames
    in the transmit path. However, GRO doesn't have a check for
    multiple levels of encapsulation and will attempt to build them.
    
    UDP tunnel GRO actually does prevent this situation but it only
    handles multiple UDP tunnels stacked on top of each other. This
    generalizes that solution to prevent any kind of tunnel stacking
    that would cause problems.
    
    Fixes: bf5a755f ("net-gre-gro: Add GRE support to the GRO stack")
    Signed-off-by: default avatarJesse Gross <jesse@kernel.org>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    [bwh: Backported to 3.16:
     - Drop the ipip and sit cases
     - Adjust context]
    Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
    23cca87f
udp_offload.c 6.21 KB