[PATCH/RFC net-next v2 0/4] net/sched: cls_flower: avoid false matching of truncated packets

[Simon Horman <simon.horman@netronome.com>]

Hi,

this series is intended to avoid false-positives which match
truncated packets against flower classifiers which match on:
* zero L4 ports or;
* zero ICMP code or type

This requires updating the flow dissector to return an error in such cases
and updating flower to not match on the result of a failed dissection.

In the case of UDP this results in a behavioural change to users of
flow_keys_dissector_keys[] and flow_keys_dissector_symmetric_keys[] -
dissection will fail on truncated packets where the IP protocol of the
packets indicates ports should be present (according to skb_flow_get_ports()).

The last patch of the series builds on the above to allow users to specify
a policy for how to handle packets whose dissection fails.

I will separately provide RFC patches to iproute2 to allow exercising the
last patch.

Changes between RFCv1 and RFCv2
* Rename new attribute in last path TCA_FLOWER_META_TRUNCATED
  after discussion with Jamal.
* Update changelog for "flow dissector" patches to make it clearer what
  the before and after behaviours are.

Simon Horman (4):
  flow dissector: return error on port dissection under-run
  flow dissector: return error on icmp dissection under-run
  net/sched: cls_flower: do not match if dissection fails
  net/sched: cls_flower: allow control of tree traversal on packet parse
    errors

 include/linux/skbuff.h       |  11 +++--
 include/uapi/linux/pkt_cls.h |   2 +
 net/core/flow_dissector.c    | 105 ++++++++++++++++++++++++-------------------
 net/sched/cls_flower.c       |  46 ++++++++++++++-----
 4 files changed, 106 insertions(+), 58 deletions(-)

-- 
2.1.4