[PATCH v2 bpf-next 0/8] bpf: Allow bpf tcp iter to do bpf_(get|set)sockopt

[Martin KaFai Lau <kafai@fb.com>]

This set is to allow bpf tcp iter to call bpf_(get|set)sockopt.

With bpf-tcp-cc, new algo rollout happens more often.  Instead of
restarting the applications to pick up the new tcp-cc, this set
allows the bpf tcp iter to call bpf_(get|set)sockopt(TCP_CONGESTION).
It is not limited to TCP_CONGESTION, the bpf tcp iter can call
bpf_(get|set)sockopt() with other options.  The bpf tcp iter can read
into all the fields of a tcp_sock, so there is a lot of flexibility
to select the desired sk to do setsockopt(), e.g. it can test for
TCP_LISTEN only and leave the established connections untouched,
or check the addr/port, or check the current tcp-cc name, ...etc.

Patch 1-4 are some cleanup and prep work in the tcp and bpf seq_file.

Patch 5 is to have the tcp seq_file iterate on the
port+addr lhash2 instead of the port only listening_hash.

Patch 6 is to have the bpf tcp iter doing batching which
then allows lock_sock.  lock_sock is needed for setsockopt.

Patch 7 allows the bpf tcp iter to call bpf_(get|set)sockopt.

v2:
- Use __GFP_NOWARN in patch 6
- Add bpf_getsockopt() in patch 7 to give a symmetrical user experience.
  selftest in patch 8 is changed to also cover bpf_getsockopt().
- Remove CAP_NET_ADMIN check in patch 7. Tracing bpf prog has already
  required CAP_SYS_ADMIN or CAP_PERFMON.
- Move some def macros to bpf_tracing_net.h in patch 8

Martin KaFai Lau (8):
  tcp: seq_file: Avoid skipping sk during tcp_seek_last_pos
  tcp: seq_file: Refactor net and family matching
  bpf: tcp: seq_file: Remove bpf_seq_afinfo from tcp_iter_state
  tcp: seq_file: Add listening_get_first()
  tcp: seq_file: Replace listening_hash with lhash2
  bpf: tcp: bpf iter batching and lock_sock
  bpf: tcp: Support bpf_(get|set)sockopt in bpf tcp iter
  bpf: selftest: Test batching and bpf_(get|set)sockopt in bpf tcp iter

 include/linux/bpf.h                           |   8 +
 include/net/inet_hashtables.h                 |   6 +
 include/net/tcp.h                             |   1 -
 kernel/bpf/bpf_iter.c                         |  22 +
 kernel/trace/bpf_trace.c                      |   7 +-
 net/core/filter.c                             |  34 ++
 net/ipv4/tcp_ipv4.c                           | 410 ++++++++++++++----
 tools/testing/selftests/bpf/network_helpers.c |  85 +++-
 tools/testing/selftests/bpf/network_helpers.h |   4 +
 .../bpf/prog_tests/bpf_iter_setsockopt.c      | 226 ++++++++++
 .../selftests/bpf/progs/bpf_iter_setsockopt.c |  72 +++
 .../selftests/bpf/progs/bpf_tracing_net.h     |   6 +
 12 files changed, 784 insertions(+), 97 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/bpf_iter_setsockopt.c
 create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_setsockopt.c

-- 
2.30.2