On Tue, Nov 23, 2021 at 3:06 PM Maciej Żenczykowski
[off-list ref] wrote:

From: Maciej Żenczykowski <redacted>

IPv4 fragments (20 byte IPv4 header) need to be translated to/from
IPv6 fragments (40 byte IPv6 header with additional 8 byte IPv6
fragmentation header).

This allows this to be done by adding an extra flag BPF_F_IPV6_FRAGMENT
to bpf_skb_change_proto().

I think this is already technically achievable via the use of
bpf_skb_adjust_room() which was added in v4.12 commit 2be7e212d541,
but this is far easier to use and eliminates the need to call two
helper functions, so it's also faster.

Cc: Lorenzo Colitti <redacted>
Signed-off-by: Maciej Żenczykowski <redacted>

Please add a selftest to exercise the new flag.

Thanks,
Song