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authorDaniel Borkmann <daniel@iogearbox.net>2020-10-11 01:40:01 +0200
committerAlexei Starovoitov <ast@kernel.org>2020-10-11 10:21:04 -0700
commitdd2ce6a5373c6f5c830be54be10775458a8bd312 (patch)
tree7940f3cc43157998f60f63a252289217166abd21 /tools/include
parentac53a0d3107c6582b690a8ab348bd637dbd0883f (diff)
downloadlinux-dd2ce6a5373c6f5c830be54be10775458a8bd312.tar.bz2
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: David Ahern <dsahern@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Reviewed-by: David Ahern <dsahern@gmail.com> Link: https://lore.kernel.org/bpf/20201010234006.7075-2-daniel@iogearbox.net
Diffstat (limited to 'tools/include')
-rw-r--r--tools/include/uapi/linux/bpf.h10
1 files changed, 7 insertions, 3 deletions
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 42d2df799397..4272cc53d478 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -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.