netlink: make range pointers in policies const

struct nla_policy is usually constant itself, but unless
we make the ranges inside constant we won't be able to
make range structs const. The ranges are not modified
by the core.

Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Reviewed-by: David Ahern <dsahern@kernel.org>
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Link: https://lore.kernel.org/r/20231025162204.132528-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

ipv6: ioam: Insertion frequency in lwtunnel output

Add support for the IOAM insertion frequency inside its lwtunnel output
function. This patch introduces a new (atomic) counter for packets,
based on which the algorithm will decide if IOAM should be added or not.

Default frequency is "1/1" (i.e., applied to all packets) for backward
compatibility. The iproute2 patch is ready and will be submitted as soon
as this one is accepted.

Previous iproute2 command:
ip -6 ro ad fc00::1/128 encap ioam6 [ mode ... ] ...

New iproute2 command:
ip -6 ro ad fc00::1/128 encap ioam6 [ freq k/n ] [ mode ... ] ...

Signed-off-by: Justin Iurman <justin.iurman@uliege.be>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

ipv6: ioam: Add support for the ip6ip6 encapsulation

This patch adds support for the ip6ip6 encapsulation by providing three encap
modes: inline, encap and auto.

Signed-off-by: Justin Iurman <justin.iurman@uliege.be>
Signed-off-by: David S. Miller <davem@davemloft.net>

ipv6: ioam: Prerequisite patch for ioam6_iptunnel

This prerequisite patch provides some minor edits (alignments, renames) and a
minor modification inside a function to facilitate the next patch by using
existing nla_* functions.

Signed-off-by: Justin Iurman <justin.iurman@uliege.be>
Signed-off-by: David S. Miller <davem@davemloft.net>

ipv6: ioam: move the check for undefined bits

The check for undefined bits in the trace type is moved from the input side to
the output side, while the input side is relaxed and now inserts default empty
values when an undefined bit is set.

Signed-off-by: Justin Iurman <justin.iurman@uliege.be>
Signed-off-by: David S. Miller <davem@davemloft.net>

ipv6: ioam: Support for IOAM injection with lwtunnels

Add support for the IOAM inline insertion (only for the host-to-host use case)
which is per-route configured with lightweight tunnels. The target is iproute2
and the patch is ready. It will be posted as soon as this patchset is merged.
Here is an overview:

$ ip -6 ro ad fc00::1/128 encap ioam6 trace type 0x800000 ns 1 size 12 dev eth0

This example configures an IOAM Pre-allocated Trace option attached to the
fc00::1/128 prefix. The IOAM namespace (ns) is 1, the size of the pre-allocated
trace data block is 12 octets (size) and only the first IOAM data (bit 0:
hop_limit + node id) is included in the trace (type) represented as a bitfield.

The reason why the in-transit (IPv6-in-IPv6 encapsulation) use case is not
implemented is explained on the patchset cover.

Signed-off-by: Justin Iurman <justin.iurman@uliege.be>
Signed-off-by: David S. Miller <davem@davemloft.net>