Add tunnel type bareudp

The Bareudp tunnel module provides a generic L3 encapsulation support for tunneling different L3 protocols inside a UDP tunnel, like MPLS, IP, NSH, etc.
Device creation & deletion

ip link add dev bareudp0 type bareudp dstport 6635 ethertype 0x8847

This creates a bareudp tunnel device which tunnels L3 traffic with ethertype
0x8847 (MPLS traffic). The destination port of the UDP header will be set to 6635
The device will listen on UDP port 6635 to receive traffic.

ip link delete bareudp0

Device creation with extended mode enabled

There are two ways to create a bareudp device for MPLS & IP with extended mode
enabled.

a)

ip link add dev  bareudp0 type bareudp dstport 6635 ethertype 0x8847 extmode 1

b)

ip link add dev  bareudp0 type bareudp dstport 6635 ethertype mpls

https://man7.org/linux/man-pages/man8/ip-link.8.html
https://www.rfc-editor.org/rfc/rfc7510
https://docs.kernel.org/networking/bareudp.html
https://lwn.net/Articles/804780/