Merge branch 'net-allow-dissecting-matching-tunnel-control-flags'

Davide Caratti says:

====================
net: allow dissecting/matching tunnel control flags

Ilya says: "for correct matching on decapsulated packets, we should match
on not only tunnel id and headers, but also on tunnel configuration flags
like TUNNEL_NO_CSUM and TUNNEL_DONT_FRAGMENT. This is done to distinguish
similar tunnels with slightly different configs. And it is important since
tunnel configuration is flow based, i.e. can be different for every packet,
even though the main tunnel port is the same."

 - patch 1 extends the kernel's flow dissector to extract these flags
   from the packet's tunnel metadata.
 - patch 2 extends TC flower to match on any combination of TUNNEL_NO_CSUM,
   TUNNEL_DONT_FRAGMENT, TUNNEL_OAM, TUNNEL_CRIT_OPT

v4:
 - fix kernel-doc warning in flow_dissector.h (thanks Jakub)

v3:
 - rebase on top of new uAPI bits and internals after commit 5832c4a77d69
   ("ip_tunnel: convert __be16 tunnel flags to bitmaps"). Use of network
   byte order is no more needed, since these bits match on metadata: convert
   netlink attributes to be u32.
 - also include TUNNEL_CRIT_OPT

v2:
 - use NL_REQ_ATTR_CHECK() where possible (thanks Jamal)
 - don't overwrite 'ret' in the error path of fl_set_key_flags()
====================

Link: https://lore.kernel.org/r/cover.1717088241.git.dcaratti@redhat.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>