[PATCH v2 bpf-next 0/5] Introduce bpf_cgroup_read_xattr

[Song Liu <song@kernel.org>]

Introduce a new kfunc bpf_cgroup_read_xattr, which can read xattr from
cgroupfs nodes. The primary users are LSMs, cgroup programs, and sched_ext.

---

Changes v1 => v2:
1. Replace 1/4 in v1 with Chritian's version (1/5 in v2).
2. Rename bpf_kernfs_read_xattr => bpf_cgroup_read_xattr, and limit access
   to cgroup only.
3. Add 5/5, which makes bpf_cgroup_read_xattr available to cgroup and
   struct_ops programs.

v1: https://lore.kernel.org/bpf/20250618233739.189106-1-song@kernel.org/

Christian Brauner (1):
  kernfs: remove iattr_mutex

Song Liu (4):
  bpf: Introduce bpf_cgroup_read_xattr to read xattr of cgroup's node
  bpf: Mark cgroup_subsys_state->cgroup RCU safe
  selftests/bpf: Add tests for bpf_cgroup_read_xattr
  bpf: Make bpf_cgroup_read_xattr available to cgroup and struct_ops
    progs

 fs/bpf_fs_kfuncs.c                            |  86 +++++++++-
 fs/kernfs/inode.c                             |  74 ++++----
 kernel/bpf/verifier.c                         |   5 +
 .../selftests/bpf/prog_tests/cgroup_xattr.c   | 145 ++++++++++++++++
 .../selftests/bpf/progs/cgroup_read_xattr.c   | 158 ++++++++++++++++++
 .../selftests/bpf/progs/read_cgroupfs_xattr.c |  60 +++++++
 6 files changed, 489 insertions(+), 39 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/cgroup_xattr.c
 create mode 100644 tools/testing/selftests/bpf/progs/cgroup_read_xattr.c
 create mode 100644 tools/testing/selftests/bpf/progs/read_cgroupfs_xattr.c

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2.47.1