• Willem de Bruijn's avatar
    packet: on direct_xmit, limit tso and csum to supported devices · 542a6af0
    Willem de Bruijn authored
    BugLink: http://bugs.launchpad.net/bugs/1642573
    
    [ Upstream commit 104ba78c ]
    
    When transmitting on a packet socket with PACKET_VNET_HDR and
    PACKET_QDISC_BYPASS, validate device support for features requested
    in vnet_hdr.
    
    Drop TSO packets sent to devices that do not support TSO or have the
    feature disabled. Note that the latter currently do process those
    packets correctly, regardless of not advertising the feature.
    
    Because of SKB_GSO_DODGY, it is not sufficient to test device features
    with netif_needs_gso. Full validate_xmit_skb is needed.
    
    Switch to software checksum for non-TSO packets that request checksum
    offload if that device feature is unsupported or disabled. Note that
    similar to the TSO case, device drivers may perform checksum offload
    correctly even when not advertising it.
    
    When switching to software checksum, packets hit skb_checksum_help,
    which has two BUG_ON checksum not in linear segment. Packet sockets
    always allocate at least up to csum_start + csum_off + 2 as linear.
    
    Tested by running github.com/wdebruij/kerneltools/psock_txring_vnet.c
    
      ethtool -K eth0 tso off tx on
      psock_txring_vnet -d $dst -s $src -i eth0 -l 2000 -n 1 -q -v
      psock_txring_vnet -d $dst -s $src -i eth0 -l 2000 -n 1 -q -v -N
    
      ethtool -K eth0 tx off
      psock_txring_vnet -d $dst -s $src -i eth0 -l 1000 -n 1 -q -v -G
      psock_txring_vnet -d $dst -s $src -i eth0 -l 1000 -n 1 -q -v -G -N
    
    v2:
      - add EXPORT_SYMBOL_GPL(validate_xmit_skb_list)
    
    Fixes: d346a3fa ("packet: introduce PACKET_QDISC_BYPASS socket option")
    Signed-off-by: default avatarWillem de Bruijn <willemb@google.com>
    Acked-by: default avatarEric Dumazet <edumazet@google.com>
    Acked-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    Signed-off-by: default avatarLuis Henriques <luis.henriques@canonical.com>
    542a6af0
dev.c 195 KB