On 6/2/20 5:19 PM, Lorenz Bauer wrote:
On Tue, 2 Jun 2020 at 15:58, Daniel Borkmann <daniel@xxxxxxxxxxxxx> wrote:Add a bpf_csum_level() helper which BPF programs can use in combination with bpf_skb_adjust_room() when they pass in BPF_F_ADJ_ROOM_NO_CSUM_RESET flag to the latter to avoid falling back to CHECKSUM_NONE. The bpf_csum_level() allows to adjust CHECKSUM_UNNECESSARY skb->csum_levels via BPF_CSUM_LEVEL_{INC,DEC} which calls __skb_{incr,decr}_checksum_unnecessary() on the skb. The helper also allows a BPF_CSUM_LEVEL_RESET which sets the skb's csum to CHECKSUM_NONE as well as a BPF_CSUM_LEVEL_QUERY to just return the current level. Without this helper, there is no way to otherwise adjust the skb->csum_level. I did not add an extra dummy flags as there is plenty of free bitspace in level argument itself iff ever needed in future. Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx> --- include/uapi/linux/bpf.h | 43 +++++++++++++++++++++++++++++++++- net/core/filter.c | 38 ++++++++++++++++++++++++++++++ tools/include/uapi/linux/bpf.h | 43 +++++++++++++++++++++++++++++++++- 3 files changed, 122 insertions(+), 2 deletions(-) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 3ba2bbbed80c..46622901cba7 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -3220,6 +3220,38 @@ union bpf_attr { * calculation. * Return * Requested value, or 0, if flags are not recognized. + * + * int bpf_csum_level(struct sk_buff *skb, u64 level)u64 flags? We can also stuff things into level I guess.
Yeah, I did mention it in the commit log. There is plenty of bit space to extend with flags in there iff ever needed. Originally, helper was called bpf_csum_adjust() but then renamed into bpf_csum_level() to be more 'topic specific' (aka do one thing and do it well...) and avoid future api overloading, so if necessary level can be used since I don't think the enum will be extended much further from what we have here anyway. [...]
Acked-by: Lorenz Bauer <lmb@xxxxxxxxxxxxxx>
Thanks!
