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Willem de Bruijn 0c19f846d5 net: accept UFO datagrams from tuntap and packet 
Tuntap and similar devices can inject GSO packets. Accept type
VIRTIO_NET_HDR_GSO_UDP, even though not generating UFO natively.

Processes are expected to use feature negotiation such as TUNSETOFFLOAD
to detect supported offload types and refrain from injecting other
packets. This process breaks down with live migration: guest kernels
do not renegotiate flags, so destination hosts need to expose all
features that the source host does.

Partially revert the UFO removal from 182e0b6b5846~1..d9d30adf5677.
This patch introduces nearly(*) no new code to simplify verification.
It brings back verbatim tuntap UFO negotiation, VIRTIO_NET_HDR_GSO_UDP
insertion and software UFO segmentation.

It does not reinstate protocol stack support, hardware offload
(NETIF_F_UFO), SKB_GSO_UDP tunneling in SKB_GSO_SOFTWARE or reception
of VIRTIO_NET_HDR_GSO_UDP packets in tuntap.

To support SKB_GSO_UDP reappearing in the stack, also reinstate
logic in act_csum and openvswitch. Achieve equivalence with v4.13 HEAD
by squashing in commit 939912216f ("net: skb_needs_check() removes
CHECKSUM_UNNECESSARY check for tx.") and reverting commit 8d63bee643
("net: avoid skb_warn_bad_offload false positives on UFO").

(*) To avoid having to bring back skb_shinfo(skb)->ip6_frag_id,
ipv6_proxy_select_ident is changed to return a __be32 and this is
assigned directly to the frag_hdr. Also, SKB_GSO_UDP is inserted
at the end of the enum to minimize code churn.

Tested
  Booted a v4.13 guest kernel with QEMU. On a host kernel before this
  patch `ethtool -k eth0` shows UFO disabled. After the patch, it is
  enabled, same as on a v4.13 host kernel.

  A UFO packet sent from the guest appears on the tap device:
    host:
      nc -l -p -u 8000 &
      tcpdump -n -i tap0

    guest:
      dd if=/dev/zero of=payload.txt bs=1 count=2000
      nc -u 192.16.1.1 8000 < payload.txt

  Direct tap to tap transmission of VIRTIO_NET_HDR_GSO_UDP succeeds,
  packets arriving fragmented:

    ./with_tap_pair.sh ./tap_send_ufo tap0 tap1
    (from https://github.com/wdebruij/kerneltools/tree/master/tests)

Changes
  v1 -> v2
    - simplified set_offload change (review comment)
    - documented test procedure

Link: http://lkml.kernel.org/r/<CAF=yD-LuUeDuL9YWPJD9ykOZ0QCjNeznPDr6whqZ9NGMNF12Mw@mail.gmail.com>
Fixes: fb652fdfe8 ("macvlan/macvtap: Remove NETIF_F_UFO advertisement.")
Reported-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
 		2017-11-24 01:37:35 +09:00
..
Kconfig openvswitch: enable NSH support 2017-11-08 16:12:33 +09:00
Makefile openvswitch: Add meter infrastructure 2017-11-13 10:37:07 +09:00
actions.c openvswitch: Add meter action support 2017-11-13 10:37:07 +09:00
conntrack.c openvswitch: conntrack: mark expected switch fall-through 2017-10-22 02:01:26 +01:00
conntrack.h openvswitch: add ct_clear action 2017-10-10 16:38:34 -07:00
datapath.c net: accept UFO datagrams from tuntap and packet 2017-11-24 01:37:35 +09:00
datapath.h openvswitch: Add meter action support 2017-11-13 10:37:07 +09:00
dp_notify.c openvswitch: reliable interface indentification in port dumps 2017-11-05 21:49:17 +09:00
flow.c net: accept UFO datagrams from tuntap and packet 2017-11-24 01:37:35 +09:00
flow.h openvswitch: enable NSH support 2017-11-08 16:12:33 +09:00
flow_netlink.c openvswitch: Make local function ovs_nsh_key_attr_size() static 2017-11-14 22:02:08 +09:00
flow_netlink.h openvswitch: enable NSH support 2017-11-08 16:12:33 +09:00
flow_table.c openvswitch: Optimize operations for OvS flow_stats. 2017-07-19 13:49:39 -07:00
flow_table.h openvswitch: Zero flows on allocation. 2015-09-22 17:33:41 -07:00
meter.c openvswitch: meter: fix NULL pointer dereference in ovs_meter_cmd_reply_start 2017-11-15 14:16:07 +09:00
meter.h openvswitch: Add meter infrastructure 2017-11-13 10:37:07 +09:00
vport-geneve.c openvswitch: do not ignore netdev errors when creating tunnel vports 2016-08-10 23:13:23 -07:00
vport-gre.c openvswitch: do not ignore netdev errors when creating tunnel vports 2016-08-10 23:13:23 -07:00
vport-internal_dev.c net: Fix inconsistent teardown and release of private netdev state. 2017-06-07 15:53:24 -04:00
vport-internal_dev.h openvswitch: introduce rtnl ops stub 2014-07-01 14:40:17 -07:00
vport-netdev.c net: Add extack to upper device linking 2017-10-04 21:39:33 -07:00
vport-netdev.h openvswitch: Use dev_queue_xmit for vport send. 2015-10-22 06:46:16 -07:00
vport-vxlan.c vxlan: get rid of redundant vxlan_dev.flags 2017-06-20 13:37:02 -04:00
vport.c openvswitch: add processing of L3 packets 2016-11-13 00:51:02 -05:00
vport.h openvswitch: pass mac_proto to ovs_vport_send 2016-11-13 00:51:02 -05:00