[PATCH bpf-next 0/2] bpf: Add more dentry kfuncs for BPF LSM programs

[David Windsor <dwindsor@gmail.com>]

BPF LSM programs often need to perform path-based access control and
security monitoring that requires walking filesystem structures. Currently,
BPF programs can access basic file information but lack the ability to
safely navigate dentry relationships or perform reference-counted
operations on filesystem objects.

This series extends the existing collection of filesystem kfuncs by adding
dentry-specific operations that enable BPF LSM programs to:

1. Safely acquire and release dentry references (bpf_dget/bpf_dput)
2. Navigate parent-child relationships (bpf_dget_parent)
3. Find dentry aliases for inodes (bpf_d_find_alias)
4. Access trusted dentry/vfsmount pointers from files
   (bpf_file_dentry/bpf_file_vfsmount)

David Windsor (2):
  bpf: Add dentry kfuncs for BPF LSM programs
  selftests/bpf: Add tests for dentry kfuncs

 fs/bpf_fs_kfuncs.c                            | 104 ++++++++++++++++++
 .../selftests/bpf/prog_tests/dentry_lsm.c     |  48 ++++++++
 .../testing/selftests/bpf/progs/dentry_lsm.c  |  51 +++++++++
 3 files changed, 203 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/dentry_lsm.c
 create mode 100644 tools/testing/selftests/bpf/progs/dentry_lsm.c

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2.43.0