mptcp: handle consistently DSS corruption

commit e32d262c upstream.

Bugged peer implementation can send corrupted DSS options, consistently
hitting a few warning in the data path. Use DEBUG_NET assertions, to
avoid the splat on some builds and handle consistently the error, dumping
related MIBs and performing fallback and/or reset according to the
subflow type.

Fixes: 6771bfd9 ("mptcp: update mptcp ack sequence from work queue")
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20241008-net-mptcp-fallback-fixes-v1-1-c6fb8e93e551@kernel.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>
[ Conflicts in mib.[ch], because commit 104125b8 ("mptcp: add mib
  for infinite map sending") is linked to a new feature, not available
  in this version. Resolving the conflicts is easy, simply adding the
  new lines declaring the new "DSS corruptions" MIB entries.
  Also removed in protocol.c and subflow.c all DEBUG_NET_WARN_ON_ONCE
  because they are not defined in this version: enough with the MIB
  counters that have been added in this commit. ]
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>