On 12/5/23 22:08, Larysa Zaremba wrote:
Implement functionality that enables drivers to expose VLAN tag
to XDP code.
VLAN tag is represented by 2 variables:
- protocol ID, which is passed to bpf code in BE
- VLAN TCI, in host byte order
Acked-by: Stanislav Fomichev <sdf@xxxxxxxxxx>
Signed-off-by: Larysa Zaremba <larysa.zaremba@xxxxxxxxx>
---
Small doc nitpicks below, but it can go in-as-is
Acked-by: Jesper Dangaard Brouer <hawk@xxxxxxxxxx>
Documentation/netlink/specs/netdev.yaml | 4 +++
Documentation/networking/xdp-rx-metadata.rst | 8 ++++-
include/net/xdp.h | 6 ++++
include/uapi/linux/netdev.h | 3 ++
net/core/xdp.c | 33 ++++++++++++++++++++
tools/include/uapi/linux/netdev.h | 3 ++
tools/net/ynl/generated/netdev-user.c | 1 +
7 files changed, 57 insertions(+), 1 deletion(-)
[...]
diff --git a/net/core/xdp.c b/net/core/xdp.c
index b6f1d6dab3f2..4869c1c2d8f3 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -736,6 +736,39 @@ __bpf_kfunc int bpf_xdp_metadata_rx_hash(const struct xdp_md *ctx, u32 *hash,
return -EOPNOTSUPP;
}
+/**
+ * bpf_xdp_metadata_rx_vlan_tag - Get XDP packet outermost VLAN tag
+ * @ctx: XDP context pointer.
+ * @vlan_proto: Destination pointer for VLAN Tag protocol identifier (TPID).
I would have written: Tag Protocol Identifier (TPID).
- like e.g. CCNA exam https://study-ccna.com/ieee-802-1q/
Capital letters leading up to the short version, but I don't think this
is a requirement. I noticed that wikipedia also got this wrong. So, I it
doesn't really matter. If you need to do a respin, I would appreciate
this changed, but you got my ACK anyway.
+ * @vlan_tci: Destination pointer for VLAN TCI (VID + DEI + PCP)
+ *
+ * In case of success, ``vlan_proto`` contains *Tag protocol identifier (TPID)*,
+ * usually ``ETH_P_8021Q`` or ``ETH_P_8021AD``, but some networks can use
+ * custom TPIDs. ``vlan_proto`` is stored in **network byte order (BE)**
+ * and should be used as follows:
+ * ``if (vlan_proto == bpf_htons(ETH_P_8021Q)) do_something();``
+ *
+ * ``vlan_tci`` contains the remaining 16 bits of a VLAN tag.
+ * Driver is expected to provide those in **host byte order (usually LE)**,
+ * so the bpf program should not perform byte conversion.
+ * According to 802.1Q standard, *VLAN TCI (Tag control information)*
+ * is a bit field that contains:
+ * *VLAN identifier (VID)* that can be read with ``vlan_tci & 0xfff``,
+ * *Drop eligible indicator (DEI)* - 1 bit,
Drop Eligible Indicator (DEI)
+ * *Priority code point (PCP)* - 3 bits.
Priority Code Point (PCP)
+ * For detailed meaning of DEI and PCP, please refer to other sources.
+ *
+ * Return:
+ * * Returns 0 on success or ``-errno`` on error.
+ * * ``-EOPNOTSUPP`` : device driver doesn't implement kfunc
+ * * ``-ENODATA`` : VLAN tag was not stripped or is not available
+ */
+__bpf_kfunc int bpf_xdp_metadata_rx_vlan_tag(const struct xdp_md *ctx,
+ __be16 *vlan_proto, u16 *vlan_tci)
+{
+ return -EOPNOTSUPP;
+}
+
__bpf_kfunc_end_defs();
