This introduces basic mptcp sockets diag support.
As IPPROTO_MPTCP excedes 8 bits, we need some changes at the inet_diag level:
a new attribute is introduced to allow user-space providing u32 protocol
values.

Patch 2 introduces new token APIs to allow traversing the existing msks, while
patch 3 bring in the actual diag implementation.

Patch 4 includes some basic functional tests

v2 -> v3:
 - changed token iterator APIs: use RCU && get_sock
 - tests cleanup

v1 -> v2
 - fixed dump issue on large dump
 - use flags for fallback, etc
 - patch 4

Paolo Abeni (4):
  inet_diag: support for wider protocol numbers
  mptcp: add msk interations helper
  mptcp: add MPTCP socket diag interface
  selftests/mptcp: add diag interface tests

 include/uapi/linux/inet_diag.h                |   1 +
 include/uapi/linux/mptcp.h                    |  17 ++
 net/core/sock.c                               |   1 +
 net/ipv4/inet_diag.c                          |  63 +++++--
 net/mptcp/Kconfig                             |   4 +
 net/mptcp/Makefile                            |   2 +
 net/mptcp/mptcp_diag.c                        | 169 ++++++++++++++++++
 net/mptcp/protocol.h                          |   2 +
 net/mptcp/token.c                             |  59 ++++++
 tools/testing/selftests/net/mptcp/Makefile    |   2 +-
 tools/testing/selftests/net/mptcp/diag.sh     | 122 +++++++++++++
 .../selftests/net/mptcp/mptcp_connect.c       |  22 ++-
 12 files changed, 442 insertions(+), 22 deletions(-)
 create mode 100644 net/mptcp/mptcp_diag.c
 create mode 100755 tools/testing/selftests/net/mptcp/diag.sh

-- 
2.26.2