Changes v1 => v2: 1. Let bpf_get_file_xattr() use const string for arg "name". (Alexei) 2. Add recursion prevention with allowlist. (Alexei) 3. Let bpf_get_file_xattr() use __vfs_getxattr() to avoid recursion, as vfs_getxattr() calls into other LSM hooks. 4. Do not use dynptr->data directly, use helper insteadd. (Andrii) 5. Fixes with bpf_get_fsverity_digest. (Eric Biggers) 6. Add documentation. (Eric Biggers) 7. Fix some compile warnings. (kernel test robot) This set enables file verification with BPF LSM and fsverity. In this solution, fsverity is used to provide reliable and efficient hash of files; and BPF LSM is used to implement signature verification (against asymmetric keys), and to enforce access control. This solution can be used to implement access control in complicated cases. For example: only signed python binary and signed python script and access special files/devices/ports. Thanks, Song Song Liu (9): bpf: Expose bpf_dynptr_slice* kfuncs for in kernel use bpf: Factor out helper check_reg_const_str() bpf: Introduce KF_ARG_PTR_TO_CONST_STR bpf: Add kfunc bpf_get_file_xattr bpf, fsverity: Add kfunc bpf_get_fsverity_digest Documentation/bpf: Add documentation for filesystem kfuncs selftests/bpf: Sort config in alphabetic order selftests/bpf: Add tests for filesystem kfuncs selftests/bpf: Add test that use fsverity and xattr to sign a file Documentation/bpf/fs_kfuncs.rst | 21 +++ Documentation/bpf/index.rst | 1 + Documentation/bpf/kfuncs.rst | 24 +++ fs/verity/fsverity_private.h | 10 ++ fs/verity/init.c | 1 + fs/verity/measure.c | 82 +++++++++ include/linux/bpf.h | 4 + kernel/bpf/verifier.c | 104 +++++++---- kernel/trace/bpf_trace.c | 71 +++++++- tools/testing/selftests/bpf/bpf_kfuncs.h | 10 ++ tools/testing/selftests/bpf/config | 3 +- .../selftests/bpf/prog_tests/fs_kfuncs.c | 132 ++++++++++++++ .../bpf/prog_tests/verify_pkcs7_sig.c | 163 +++++++++++++++++- .../selftests/bpf/progs/test_fsverity.c | 46 +++++ .../selftests/bpf/progs/test_get_xattr.c | 37 ++++ .../selftests/bpf/progs/test_sig_in_xattr.c | 82 +++++++++ .../bpf/progs/test_verify_pkcs7_sig.c | 8 +- .../testing/selftests/bpf/verify_sig_setup.sh | 25 +++ 18 files changed, 775 insertions(+), 49 deletions(-) create mode 100644 Documentation/bpf/fs_kfuncs.rst create mode 100644 tools/testing/selftests/bpf/prog_tests/fs_kfuncs.c create mode 100644 tools/testing/selftests/bpf/progs/test_fsverity.c create mode 100644 tools/testing/selftests/bpf/progs/test_get_xattr.c create mode 100644 tools/testing/selftests/bpf/progs/test_sig_in_xattr.c -- 2.34.1
