[PATCH bpf 0/3] Fix csum unnecessary on bpf_skb_adjust_room

[Daniel Borkmann <daniel@xxxxxxxxxxxxx>]

This series fixes an issue originally reported by Lorenz Bauer where using
the bpf_skb_adjust_room() helper hid a checksum bug since it wasn't adjusting
CHECKSUM_UNNECESSARY's skb->csum_level after decap. The fix is two-fold:
 i) We do a safe reset in bpf_skb_adjust_room() to CHECKSUM_NONE with an opt-
    out flag BPF_F_ADJ_ROOM_NO_CSUM_RESET.
ii) We add a new bpf_csum_level() for the latter in order to allow users to
    manually inc/dec the skb->csum_level when needed.
The series is rebased against latest bpf-next tree. It can be applied there,
or to bpf after the merge win sync from net-next.

Thanks!

Daniel Borkmann (3):
  bpf: Fix up bpf_skb_adjust_room helper's skb csum setting
  bpf: add csum_level helper for fixing up csum levels
  bpf, selftests: adapt cls_redirect to call csum_level helper

 include/linux/skbuff.h                        |  8 +++
 include/uapi/linux/bpf.h                      | 51 ++++++++++++++++++-
 net/core/filter.c                             | 46 ++++++++++++++++-
 tools/include/uapi/linux/bpf.h                | 51 ++++++++++++++++++-
 .../selftests/bpf/progs/test_cls_redirect.c   |  9 ++--
 5 files changed, 158 insertions(+), 7 deletions(-)

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2.21.0