[RFC bpf-next 0/7] net: flow_dissector: trigger BPF hook when called from eth_get_headlen

[Stanislav Fomichev <sdf@google.com>]

Currently, when eth_get_headlen calls flow dissector, it doesn't pass any
skb. Because we use passed skb to lookup associated networking namespace
to find whether we have a BPF program attached or not, we always use
C-based flow dissector in this case.

The goal of this patch series is to add new networking namespace argument
to the eth_get_headlen and make BPF flow dissector programs be able to
work in the skb-less case.

The series goes like this:
1. introduce __init_skb and __init_skb_shinfo; those will be used to
   initialize temporary skb
2. introduce skb_net which can be used to get networking namespace
   associated with an skb
3. add new optional network namespace argument to __skb_flow_dissect and
   plumb through the callers
4. add new __flow_bpf_dissect which constructs temporary on-stack skb
   (using __init_skb) and calls BPF flow dissector program
5. convert flow dissector BPF_PROG_TEST_RUN to skb-less mode to show that
   it works
6. add selftest that makes sure going over the packet bounds in
   bpf_skb_load_bytes with on-stack skb doesn't cause any problems
7. add new net namespace argument go eth_get_headlen and convert the
   callers

Stanislav Fomichev (7):
  net: introduce __init_skb and __init_skb_shinfo helpers
  net: introduce skb_net helper
  net: plumb network namespace into __skb_flow_dissect
  net: flow_dissector: handle no-skb use case
  bpf: when doing BPF_PROG_TEST_RUN for flow dissector use no-skb mode
  selftests/bpf: add flow dissector bpf_skb_load_bytes helper test
  net: flow_dissector: pass net argument to the eth_get_headlen

 drivers/net/ethernet/broadcom/bnxt/bnxt.c     |   2 +-
 drivers/net/ethernet/hisilicon/hns/hns_enet.c |   3 +-
 .../net/ethernet/hisilicon/hns3/hns3_enet.c   |   3 +-
 drivers/net/ethernet/intel/fm10k/fm10k_main.c |   2 +-
 drivers/net/ethernet/intel/i40e/i40e_txrx.c   |   3 +-
 drivers/net/ethernet/intel/iavf/iavf_txrx.c   |   2 +-
 drivers/net/ethernet/intel/ice/ice_txrx.c     |   2 +-
 drivers/net/ethernet/intel/igb/igb_main.c     |   2 +-
 drivers/net/ethernet/intel/igc/igc_main.c     |   2 +-
 drivers/net/ethernet/intel/ixgbe/ixgbe_main.c |   2 +-
 .../net/ethernet/intel/ixgbevf/ixgbevf_main.c |   3 +-
 .../net/ethernet/mellanox/mlx5/core/en_tx.c   |   3 +-
 drivers/net/tun.c                             |   3 +-
 include/linux/etherdevice.h                   |   2 +-
 include/linux/skbuff.h                        |  23 +++-
 net/bpf/test_run.c                            |  52 +++------
 net/core/flow_dissector.c                     | 105 +++++++++++++-----
 net/core/skbuff.c                             |  78 +++++++------
 net/ethernet/eth.c                            |   8 +-
 tools/testing/selftests/bpf/test_progs.c      |  49 ++++++++
 20 files changed, 227 insertions(+), 122 deletions(-)

-- 
2.20.1.611.gfbb209baf1-goog