[v2,bpf-next,0/2] add TCP_BPF_SOCK_OPS_CB_FLAGS to bpf_*sockopt()

Message

Alan Maguire Aug. 8, 2024, 3:05 p.m. UTC

As previously discussed here [1], long-lived sockets can miss
a chance to set additional callbacks if a sock ops program
was not attached early in their lifetime.  Adding support
to bpf_setsockopt() to set callback flags (and bpf_getsockopt()
to retrieve them) provides other opportunities to enable callbacks,
either directly via a cgroup/setsockopt intercepted setsockopt()
or via a socket iterator.

Patch 1 adds bpf_[get|set]sockopt() support; patch 2 adds testing
for it via a sockops programs, along with verification via a
cgroup/getsockopt program.

Changes since v1 [2]:

- Removed unneeded READ_ONCE() (Martin, patch 1)
- Reworked sockopt test to leave existing tests undisturbed while adding
  test_nonstandard_opt() test to cover the TCP_BPF_SOCK_OPS_CB_FLAGS
  case; test verifies that value set via bpf_setsockopt() is what we
  expect via a call to getsockopt() which is caught by a
  cgroup/getsockopt program to provide the flags value (Martin, patch 2)
- Removed unneeded iterator test (Martin)

[1] https://lore.kernel.org/bpf/[e-mail]/
[2] https://lore.kernel.org/bpf/[e-mail]/

Alan Maguire (2):
  bpf/bpf_get,set_sockopt: add option to set TCP-BPF sock ops flags
  selftests/bpf: add sockopt tests for TCP_BPF_SOCK_OPS_CB_FLAGS

 include/uapi/linux/bpf.h                      |  3 +-
 net/core/filter.c                             | 15 ++++++
 tools/include/uapi/linux/bpf.h                |  3 +-
 .../selftests/bpf/prog_tests/setget_sockopt.c | 47 +++++++++++++++++++
 .../selftests/bpf/progs/setget_sockopt.c      | 24 ++++++++--
 5 files changed, 87 insertions(+), 5 deletions(-)