[PATCH bpf-next v6 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:
* use new kernel context (struct bpf_flow_dissector) for flow dissector
  programs; this makes it easy to distinguish between skb and no-skb
  case and supports calling BPF flow dissector on a chunk of raw data
* convert BPF_PROG_TEST_RUN to use raw data
* plumb network namespace into __skb_flow_dissect from all callers
* handle no-skb case in __skb_flow_dissect
* update eth_get_headlen to include net namespace argument and
  convert all existing users
* add selftest to make sure bpf_skb_load_bytes is not allowed in
  the no-skb mode
* extend test_progs to exercise skb-less flow dissection as well
* stop adjusting nhoff/thoff by ETH_HLEN in BPF_PROG_TEST_RUN

v6:
* more suggestions by Alexei:
  * eth_get_headlen now takes net dev, not net namespace
  * test skb-less case via tun eth_get_headlen
* fix return errors in bpf_flow_load
* don't adjust nhoff/thoff by ETH_HLEN

v5:
* API changes have been submitted via bpf/stable tree

v4:
* prohibit access to vlan fields as well (otherwise, inconsistent
  between skb/skb-less cases)
* drop extra unneeded check for skb->vlan_present in bpf_flow.c

v3:
* new kernel xdp_buff-like context per Alexei suggestion
* drop skb_net helper
* properly clamp flow_keys->nhoff

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):
  flow_dissector: switch kernel context to struct bpf_flow_dissector
  bpf: when doing BPF_PROG_TEST_RUN for flow dissector use no-skb mode
  net: plumb network namespace into __skb_flow_dissect
  flow_dissector: handle no-skb use case
  net: pass net_device argument to the eth_get_headlen
  selftests/bpf: add flow dissector bpf_skb_load_bytes helper test
  selftests/bpf: run flow dissector tests in skb-less mode
  selftests/bpf: properly return error from bpf_flow_load
  bpf/flow_dissector: don't adjust nhoff by ETH_HLEN in
    BPF_PROG_TEST_RUN

 .../net/ethernet/aquantia/atlantic/aq_ring.c  |   3 +-
 drivers/net/ethernet/broadcom/bnxt/bnxt.c     |   2 +-
 drivers/net/ethernet/hisilicon/hns/hns_enet.c |   2 +-
 .../net/ethernet/hisilicon/hns3/hns3_enet.c   |   2 +-
 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   |   2 +-
 drivers/net/tun.c                             |   3 +-
 include/linux/etherdevice.h                   |   2 +-
 include/linux/skbuff.h                        |  28 +++--
 include/net/flow_dissector.h                  |   7 ++
 include/net/sch_generic.h                     |  11 +-
 net/bpf/test_run.c                            |  48 +++-----
 net/core/filter.c                             | 105 ++++++++++++----
 net/core/flow_dissector.c                     |  90 +++++++-------
 net/ethernet/eth.c                            |   8 +-
 .../selftests/bpf/flow_dissector_load.c       |   2 +-
 .../selftests/bpf/flow_dissector_load.h       |  24 +++-
 .../selftests/bpf/prog_tests/flow_dissector.c | 113 ++++++++++++++++--
 .../prog_tests/flow_dissector_load_bytes.c    |  48 ++++++++
 tools/testing/selftests/bpf/progs/bpf_flow.c  |  79 +++++++-----
 27 files changed, 411 insertions(+), 186 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/flow_dissector_load_bytes.c

-- 
2.21.0.593.g511ec345e18-goog