[RFC bpf-next v2 0/9] 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 a bunch of skb initialization helpers; 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. prepare for new bpf flow dissector flavor, create some common routines
   and do some renames
5. restrict access to a limited set of __sk_buff fields from flow
   dissector programs
6. add new bpf_flow_dissect which uses temporary per-cpu skb and calls
   BPF flow dissector program
7. convert flow dissector BPF_PROG_TEST_RUN to skb-less mode to show that
   it works
8. add selftest that makes sure going over the packet bounds in
   bpf_skb_load_bytes with shinfo-less skb doesn't cause any problems
9. add new net namespace argument to eth_get_headlen and convert the
   callers

v2:
* moved temporary skb from stack into percpu (avoids memset of ~200 bytes
  per packet)
* tightened down access to __sk_buff fields from flow dissector programs to
  avoid touching shinfo (whitelist only relevant fields)
* addressed suggestions from Willem

Stanislav Fomichev (9):
  net: introduce __init_skb{,_data,_shinfo} helpers
  net: introduce skb_net helper
  net: plumb network namespace into __skb_flow_dissect
  net: flow_dissector: prepare for no-skb use case
  flow_dissector: allow access only to a subset of __sk_buff fields
  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                        |  48 +++++--
 net/bpf/test_run.c                            |  48 ++-----
 net/core/filter.c                             |  13 +-
 net/core/flow_dissector.c                     | 135 +++++++++++++-----
 net/core/skbuff.c                             |  76 +++++-----
 net/ethernet/eth.c                            |   8 +-
 .../prog_tests/flow_dissector_load_bytes.c    |  50 +++++++
 21 files changed, 269 insertions(+), 143 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/flow_dissector_load_bytes.c

-- 
2.21.0.225.g810b269d1ac-goog