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Message-Id: <20201008213148.26848-2-daniel@iogearbox.net>
Date: Thu, 8 Oct 2020 23:31:43 +0200
From: Daniel Borkmann <daniel@...earbox.net>
To: ast@...nel.org
Cc: daniel@...earbox.net, john.fastabend@...il.com,
netdev@...r.kernel.org, bpf@...r.kernel.org,
David Ahern <dsahern@...il.com>
Subject: [PATCH bpf-next 1/6] 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@...il.com>
Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
---
include/uapi/linux/bpf.h | 10 +++++++---
tools/include/uapi/linux/bpf.h | 10 +++++++---
2 files changed, 14 insertions(+), 6 deletions(-)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index d83561e8cd2c..8e8941535c28 100644
--- a/include/uapi/linux/bpf.h
+++ b/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.
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index d83561e8cd2c..8e8941535c28 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.
--
2.17.1
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