[PATCH v2 0/6] Add _opts variant for bpf_*_get_fd_by_id()

[Roberto Sassu]

From: Roberto Sassu <roberto.sassu@xxxxxxxxxx>

Add the _opts variant for bpf_*_get_fd_by_id() functions, to be able to
pass to the kernel more options, when requesting a fd of an eBPF object.

Pass the options through a newly introduced structure,
bpf_get_fd_by_id_opts, which currently contains open_flags (the other two
members are for compatibility and for padding).

open_flags allows the caller to request specific permissions to access a
map (e.g. read-only). This is useful for example in the situation where a
map is write-protected.

Besides patches 2-6, which introduce the new variants and the data
structure, patch 1 fixes the LIBBPF_1.0.0 declaration in libbpf.map.

Changelog

v1:
 - Don't CC stable kernel mailing list for patch 1 (suggested by Andrii)
 - Rename bpf_get_fd_opts struct to bpf_get_fd_by_id_opts (suggested by
   Andrii)
 - Move declaration of _opts variants after non-opts variants (suggested by
   Andrii)
 - Correctly initialize bpf_map_info, fix style issues, use map from
   skeleton, check valid fd in the test (suggested by Andrii)
 - Rename libbpf_get_fd_opts test to libbpf_get_fd_by_id_opts

Roberto Sassu (6):
  libbpf: Fix LIBBPF_1.0.0 declaration in libbpf.map
  libbpf: Introduce bpf_get_fd_by_id_opts and
    bpf_map_get_fd_by_id_opts()
  libbpf: Introduce bpf_prog_get_fd_by_id_opts()
  libbpf: Introduce bpf_btf_get_fd_by_id_opts()
  libbpf: Introduce bpf_link_get_fd_by_id_opts()
  selftests/bpf: Add tests for _opts variants of bpf_*_get_fd_by_id()

 tools/lib/bpf/bpf.c                           | 48 +++++++++-
 tools/lib/bpf/bpf.h                           | 16 ++++
 tools/lib/bpf/libbpf.map                      |  6 +-
 tools/testing/selftests/bpf/DENYLIST.s390x    |  1 +
 .../bpf/prog_tests/libbpf_get_fd_by_id_opts.c | 87 +++++++++++++++++++
 .../bpf/progs/test_libbpf_get_fd_by_id_opts.c | 36 ++++++++
 6 files changed, 189 insertions(+), 5 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/libbpf_get_fd_by_id_opts.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_libbpf_get_fd_by_id_opts.c

-- 
2.25.1