• Davide Caratti's avatar
    net/sched: fix corrupted L2 header with MPLS 'push' and 'pop' actions · fa4e0f88
    Davide Caratti authored
    the following script:
    
     # tc qdisc add dev eth0 clsact
     # tc filter add dev eth0 egress protocol ip matchall \
     > action mpls push protocol mpls_uc label 0x355aa bos 1
    
    causes corruption of all IP packets transmitted by eth0. On TC egress, we
    can't rely on the value of skb->mac_len, because it's 0 and a MPLS 'push'
    operation will result in an overwrite of the first 4 octets in the packet
    L2 header (e.g. the Destination Address if eth0 is an Ethernet); the same
    error pattern is present also in the MPLS 'pop' operation. Fix this error
    in act_mpls data plane, computing 'mac_len' as the difference between the
    network header and the mac header (when not at TC ingress), and use it in
    MPLS 'push'/'pop' core functions.
    
    v2: unbreak 'make htmldocs' because of missing documentation of 'mac_len'
        in skb_mpls_pop(), reported by kbuild test robot
    
    CC: Lorenzo Bianconi <lorenzo@kernel.org>
    Fixes: 2a2ea508 ("net: sched: add mpls manipulation actions to TC")
    Reviewed-by: default avatarSimon Horman <simon.horman@netronome.com>
    Acked-by: default avatarJohn Hurley <john.hurley@netronome.com>
    Signed-off-by: default avatarDavide Caratti <dcaratti@redhat.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    fa4e0f88
act_mpls.c 10.5 KB