Commit Graph
2 Commits
Author SHA1 Message Date
Paul Chaignon 0c85f5a154 bpf: Clarify the meaning of BPF_F_PSEUDO_HDR
In the bpf_l4_csum_replace helper, the BPF_F_PSEUDO_HDR flag should only
be set if the modified header field is part of the pseudo-header.

If you modify for example the UDP ports and pass BPF_F_PSEUDO_HDR,
inet_proto_csum_replace4 will update skb->csum even though it shouldn't
(the port and the UDP checksum updates null each other).

Signed-off-by: Paul Chaignon <paul.chaignon@gmail.com>
Link: https://lore.kernel.org/r/5126ef84ba75425b689482cbc98bffe75e5d8ab0.1744102490.git.paul.chaignon@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-04-29 11:33:37 -07:00
Paul Chaignon 7de6a44a0f bpf: Clarify role of BPF_F_RECOMPUTE_CSUM
BPF_F_RECOMPUTE_CSUM doesn't update the actual L3 and L4 checksums in
the packet, but simply updates skb->csum (according to skb->ip_summed).
This patch clarifies that to avoid confusions.

Signed-off-by: Paul Chaignon <paul.chaignon@gmail.com>
Link: https://lore.kernel.org/r/ff6895d42936f03dbb82334d8bcfd50e00c79086.1744102490.git.paul.chaignon@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-04-29 11:33:37 -07:00