KFunc bpf_xdp_metadata_rx_vlan_tag
Get XDP packet outermost VLAN tag
Definition
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,
Priority code point (PCP) - 3 bits.
For detailed meaning of DEI and PCP, please refer to other sources.
ctx: XDP context pointer.
vlan_proto: Destination pointer for VLAN Tag protocol identifier (TPID).
vlan_tci: Destination pointer for VLAN TCI (VID + DEI + PCP)
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
int bpf_xdp_metadata_rx_vlan_tag(const struct xdp_md *ctx, __be16 *vlan_proto, u16 *vlan_tci)
Usage
Docs could be improved
This part of the docs is incomplete, contributions are very welcome
Program types
The following program types can make use of this kfunc:
Example
Docs could be improved
This part of the docs is incomplete, contributions are very welcome