Merge branch 'some-pktgen-fixes-improvments-part-ii'

Peter Seiderer says:

====================
Some pktgen fixes/improvments (part II)

While taking a look at '[PATCH net] pktgen: Avoid out-of-range in
get_imix_entries' ([1]) and '[PATCH net v2] pktgen: Avoid out-of-bounds
access in get_imix_entries' ([2], [3]) and doing some tests and code review
I detected that the /proc/net/pktgen/... parsing logic does not honour the
user given buffer bounds (resulting in out-of-bounds access).

This can be observed e.g. by the following simple test (sometimes the
old/'longer' previous value is re-read from the buffer):

        $ echo add_device lo@0 > /proc/net/pktgen/kpktgend_0

        $ echo "min_pkt_size 12345" > /proc/net/pktgen/lo\@0 && grep min_pkt_size /proc/net/pktgen/lo\@0
Params: count 1000  min_pkt_size: 12345  max_pkt_size: 0
Result: OK: min_pkt_size=12345

        $ echo -n "min_pkt_size 123" > /proc/net/pktgen/lo\@0 && grep min_pkt_size /proc/net/pktgen/lo\@0
Params: count 1000  min_pkt_size: 12345  max_pkt_size: 0
Result: OK: min_pkt_size=12345

        $ echo "min_pkt_size 123" > /proc/net/pktgen/lo\@0 && grep min_pkt_size /proc/net/pktgen/lo\@0
Params: count 1000  min_pkt_size: 123  max_pkt_size: 0
Result: OK: min_pkt_size=123

So fix the out-of-bounds access (and some minor findings) and add a simple
proc_net_pktgen selftest...

Patch set splited into part I (now already applied to net-next)

- net: pktgen: replace ENOTSUPP with EOPNOTSUPP
- net: pktgen: enable 'param=value' parsing
- net: pktgen: fix hex32_arg parsing for short reads
- net: pktgen: fix 'rate 0' error handling (return -EINVAL)
- net: pktgen: fix 'ratep 0' error handling (return -EINVAL)
- net: pktgen: fix ctrl interface command parsing
- net: pktgen: fix access outside of user given buffer in pktgen_thread_write()

nd part II (this one):

- net: pktgen: use defines for the various dec/hex number parsing digits lengths
- net: pktgen: fix mix of int/long
- net: pktgen: remove extra tmp variable (re-use len instead)
- net: pktgen: remove some superfluous variable initializing
- net: pktgen: fix mpls maximum labels list parsing
- net: pktgen: fix access outside of user given buffer in pktgen_if_write()
- net: pktgen: fix mpls reset parsing
- net: pktgen: remove all superfluous index assignements
- selftest: net: add proc_net_pktgen

[1] https://lore.kernel.org/netdev/20241006221221.3744995-1-artem.chernyshev@red-soft.ru/
[2] https://lore.kernel.org/netdev/20250109083039.14004-1-pchelkin@ispras.ru/
[3] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=76201b5979768500bca362871db66d77cb4c225e
====================

Link: https://patch.msgid.link/20250227135604.40024-1-ps.report@gmx.net
Signed-off-by: Paolo Abeni <pabeni@redhat.com>