[PATCH net v3 0/2] net: Fix inet_proto_csum_replace_by_diff for IPv6

[Paul Chaignon <paul.chaignon@gmail.com>]

This patchset fixes a bug that causes skb->csum to hold an incorrect
value when calling inet_proto_csum_replace_by_diff for an IPv6 packet
in CHECKSUM_COMPLETE state. This bug affects BPF helper
bpf_l4_csum_replace and IPv6 ILA in adj-transport mode.

In those cases, inet_proto_csum_replace_by_diff updates the L4 checksum
field after an IPv6 address change. These two changes cancel each other
in terms of checksum, so skb->csum shouldn't be updated.

Changes in v3:
  - Rebase.
  - Use proper tag for reference, per Paolo's suggestion.
Changes in v2:
  - For BPF, pass the new flag is_ipv6 to
    inet_proto_csum_replace_by_diff directly instead of calling
    inet_proto_csum_replace16.
  - Document the new BPF helper flag.
  - Fix the usage of inet_proto_csum_replace_by_diff in ILA in a
    separate patch.
  - Rebase on net tree.
  - Link: https://lore.kernel.org/bpf/aCz84JU60wd8etiT@mail.gmail.com/

Paul Chaignon (2):
  net: Fix checksum update for ILA adj-transport
  bpf: Fix L4 csum update on IPv6 in CHECKSUM_COMPLETE

 include/net/checksum.h         | 2 +-
 include/uapi/linux/bpf.h       | 2 ++
 net/core/filter.c              | 5 +++--
 net/core/utils.c               | 4 ++--
 net/ipv6/ila/ila_common.c      | 6 +++---
 tools/include/uapi/linux/bpf.h | 2 ++
 6 files changed, 13 insertions(+), 8 deletions(-)

-- 
2.43.0