Commit Graph
3 Commits
Author SHA1 Message Date
Paul Chaignon 9b06cd15e0 bpf: Clarify handling of mark and tstamp by redirect_peer
When switching network namespaces with the bpf_redirect_peer helper, the
skb->mark and skb->tstamp fields are not zeroed out like they can be on
a typical netns switch. This patch clarifies that in the helper
description.

Signed-off-by: Paul Chaignon <paul.chaignon@gmail.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://patch.msgid.link/ccc86af26d43c5c0b776bcba2601b7479c0d46d0.1746460653.git.paul.chaignon@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-06-16 08:51:34 -07:00
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