Merge branch 'csum-fixes'

Daniel Borkmann says:

====================
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!
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>