Merge branch 'net-fib_rules-add-flow-label-selector-support'

Merge branch 'net-fib_rules-add-flow-label-selector-support'

Ido Schimmel says:

====================
net: fib_rules: Add flow label selector support

In some deployments users would like to encode path information into
certain bits of the IPv6 flow label, the UDP source port and the DSCP
and use this information to route packets accordingly.

Redirecting traffic to a routing table based on the flow label is not
currently possible with Linux as FIB rules cannot match on it despite
the flow label being available in the IPv6 flow key.

This patchset extends FIB rules to match on the flow label with a mask.
Future patches will add mask attributes to L4 ports and DSCP matches.

Patches #1-#5 gradually extend FIB rules to match on the flow label.

Patches #6-#7 allow user space to specify a flow label in route get
requests. This is useful for both debugging and testing.

Patch #8 adjusts the fib6_table_lookup tracepoint to print the flow
label to the trace buffer for better observability.

Patch #9 extends the FIB rule selftest with flow label test cases while
utilizing the route get functionality from patch #6.
====================

Link: https://patch.msgid.link/20241216171201.274644-1-idosch@nvidia.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>