Commit 7cb779a6 authored Sep 11, 2023 by Stanislav Fomichev Committed by Daniel Borkmann Sep 11, 2023

bpf: Clarify error expectations from bpf_clone_redirect



Commit 151e887d ("veth: Fixing transmit return status for dropped
packets") exposed the fact that bpf_clone_redirect is capable of
returning raw NET_XMIT_XXX return codes.

This is in the conflict with its UAPI doc which says the following:
"0 on success, or a negative error in case of failure."

Update the UAPI to reflect the fact that bpf_clone_redirect can
return positive error numbers, but don't explicitly define
their meaning.

Reported-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230911194731.286342-1-sdf@google.com

parent 9458964a

include/uapi/linux/bpf.h

+3 −1

Original line number	Diff line number	Diff line
		@@ -1962,7 +1962,9 @@ union bpf_attr {
		* performed again, if the helper is used in combination with
		* direct packet access.
		* Return
		* 0 on success, or a negative error in case of failure.
		* 0 on success, or a negative error in case of failure. Positive
		* error indicates a potential drop or congestion in the target
		* device. The particular positive error codes are not defined.
		*
		* u64 bpf_get_current_pid_tgid(void)
		* Description

tools/include/uapi/linux/bpf.h

+3 −1

Original line number	Diff line number	Diff line
		@@ -1962,7 +1962,9 @@ union bpf_attr {
		* performed again, if the helper is used in combination with
		* direct packet access.
		* Return
		* 0 on success, or a negative error in case of failure.
		* 0 on success, or a negative error in case of failure. Positive
		* error indicates a potential drop or congestion in the target
		* device. The particular positive error codes are not defined.
		*
		* u64 bpf_get_current_pid_tgid(void)
		* Description