[PATCH bpf-next v3 0/5] bpf: add MPTCP subflow support

[Nicolas Rybowski]

Previously it was not possible to make a distinction between plain TCP
sockets and MPTCP subflow sockets on the BPF_PROG_TYPE_SOCK_OPS hook.

This patch series now enables a fine control of subflow sockets. In its
current state, it allows to put different sockopt on each subflow from a
same MPTCP connection (socket mark, TCP congestion algorithm, ...) using
BPF programs.

It should also be the basis of exposing MPTCP-specific fields through BPF.

v2 -> v3:
- minor modifications in new MPTCP selftests (Song). More details in patch notes.
- rebase on latest bpf-next
- the new is_mptcp field in bpf_tcp_sock is left as an __u32 to keep cohesion 
with the is_fullsock field from bpf_sock_ops. Also it seems easier with a __u32 
on the verifier side.

v1 -> v2:
- add basic mandatory selftests for the new helper and is_mptcp field (Alexei)
- rebase on latest bpf-next

Nicolas Rybowski (5):
  bpf: expose is_mptcp flag to bpf_tcp_sock
  mptcp: attach subflow socket to parent cgroup
  bpf: add 'bpf_mptcp_sock' structure and helper
  bpf: selftests: add MPTCP test base
  bpf: selftests: add bpf_mptcp_sock() verifier tests

 include/linux/bpf.h                           |  33 +++++
 include/uapi/linux/bpf.h                      |  15 +++
 kernel/bpf/verifier.c                         |  30 +++++
 net/core/filter.c                             |  13 +-
 net/mptcp/Makefile                            |   2 +
 net/mptcp/bpf.c                               |  72 +++++++++++
 net/mptcp/subflow.c                           |  27 ++++
 scripts/bpf_helpers_doc.py                    |   2 +
 tools/include/uapi/linux/bpf.h                |  15 +++
 tools/testing/selftests/bpf/config            |   1 +
 tools/testing/selftests/bpf/network_helpers.c |  37 +++++-
 tools/testing/selftests/bpf/network_helpers.h |   3 +
 .../testing/selftests/bpf/prog_tests/mptcp.c  | 118 ++++++++++++++++++
 tools/testing/selftests/bpf/progs/mptcp.c     |  48 +++++++
 tools/testing/selftests/bpf/verifier/sock.c   |  63 ++++++++++
 15 files changed, 473 insertions(+), 6 deletions(-)
 create mode 100644 net/mptcp/bpf.c
 create mode 100644 tools/testing/selftests/bpf/prog_tests/mptcp.c
 create mode 100644 tools/testing/selftests/bpf/progs/mptcp.c

-- 
2.28.0