[PATCH v2 0/5] bpf: skb_adjust_room helper refactor and tunnel decap flags

This series refactors the bpf_skb_adjust_room() helper to support tunnel
decapsulation with L4 and IPXIP modes, in addition to the existing L3
decapsulation support.

The changes are structured as follows:
1. Name the enum for BPF_FUNC_skb_adjust_room flags
2. Add new BPF_F_ADJ_ROOM_DECAP_* flags for L4 and IPXIP decap modes
3. Introduce helper masks to simplify validation logic
4. Enable the new decap flags and add guard rails for invalid combinations
5. Clear tunnel GSO state when decapsulating in skb_adjust_room

These patches enable BPF programs to efficiently decapsulate various tunnel
encapsulation formats and properly handle GSO state transitions.

Changes v1 -> v2:
- Patch 3: Decap flag acceptance intentionally remains L3-only
  while adding the helper masks.
- Patch 4: Decap with L4/IPXIP support enabled with guard rails.

Nick Hudson (5):
  bpf: name the enum for BPF_FUNC_skb_adjust_room flags
  bpf: add BPF_F_ADJ_ROOM_DECAP_* flags for tunnel decapsulation
  bpf: add helper masks for ADJ_ROOM flags and encap validation
  bpf: allow new DECAP flags and add guard rails
  bpf: clear decap tunnel GSO state in skb_adjust_room

 include/uapi/linux/bpf.h       |  36 ++++++++++-
 net/core/filter.c              | 107 +++++++++++++++++++++++++++------
 tools/include/uapi/linux/bpf.h |  36 ++++++++++-
 3 files changed, 156 insertions(+), 23 deletions(-)

-- 
2.34.1