Commit dd2ce6a5 authored by Daniel Borkmann's avatar Daniel Borkmann Committed by Alexei Starovoitov
Browse files

bpf: Improve bpf_redirect_neigh helper description 



Follow-up to address David's feedback that we should better describe internals
of the bpf_redirect_neigh() helper.

Suggested-by: default avatarDavid Ahern <dsahern@gmail.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Reviewed-by: default avatarDavid Ahern <dsahern@gmail.com>
Link: https://lore.kernel.org/bpf/20201010234006.7075-2-daniel@iogearbox.net
parent ac53a0d3

include/uapi/linux/bpf.h

+7 −3
Original line number Diff line number Diff line
@@ -3679,10 +3679,14 @@ union bpf_attr { 
 * 		Redirect the packet to another net device of index *ifindex*

 * 		and fill in L2 addresses from neighboring subsystem. This helper

 * 		is somewhat similar to **bpf_redirect**\ (), except that it

 * 		fills in e.g. MAC addresses based on the L3 information from

 * 		the packet. This helper is supported for IPv4 and IPv6 protocols.

 * 		populates L2 addresses as well, meaning, internally, the helper

 * 		performs a FIB lookup based on the skb's networking header to

 * 		get the address of the next hop and then relies on the neighbor

 * 		lookup for the L2 address of the nexthop.

 *

 * 		The *flags* argument is reserved and must be 0. The helper is

 * 		currently only supported for tc BPF program types.

 * 		currently only supported for tc BPF program types, and enabled

 * 		for IPv4 and IPv6 protocols.

 * 	Return

 * 		The helper returns **TC_ACT_REDIRECT** on success or

 * 		**TC_ACT_SHOT** on error.

tools/include/uapi/linux/bpf.h

+7 −3
Original line number Diff line number Diff line
@@ -3679,10 +3679,14 @@ union bpf_attr { 
 * 		Redirect the packet to another net device of index *ifindex*

 * 		and fill in L2 addresses from neighboring subsystem. This helper

 * 		is somewhat similar to **bpf_redirect**\ (), except that it

 * 		fills in e.g. MAC addresses based on the L3 information from

 * 		the packet. This helper is supported for IPv4 and IPv6 protocols.

 * 		populates L2 addresses as well, meaning, internally, the helper

 * 		performs a FIB lookup based on the skb's networking header to

 * 		get the address of the next hop and then relies on the neighbor

 * 		lookup for the L2 address of the nexthop.

 *

 * 		The *flags* argument is reserved and must be 0. The helper is

 * 		currently only supported for tc BPF program types.

 * 		currently only supported for tc BPF program types, and enabled

 * 		for IPv4 and IPv6 protocols.

 * 	Return

 * 		The helper returns **TC_ACT_REDIRECT** on success or

 * 		**TC_ACT_SHOT** on error.

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