From: Willem de Bruijn <willemdebruijn.ker...@gmail.com>
Date: Wed, 26 Oct 2016 11:23:07 -0400
> From: Willem de Bruijn <will...@google.com>
>
> 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: d346a3fae3ff ("packet: introduce PACKET_QDISC_BYPASS socket option")
> Signed-off-by: Willem de Bruijn <will...@google.com>
Applied and queued up for -stable.
