[PATCH bpf-next] bpf: add small subset of SECURITY_PATH hooks to BPF sleepable_lsm_hooks list

[Matt Bobrowski]

security_path_* based LSM hooks appear to be generally missing from
the sleepable_lsm_hooks list. Initially add a small subset of them to
the preexisting sleepable_lsm_hooks list so that sleepable BPF helpers
like bpf_d_path() can be used from sleepable BPF LSM based programs.

The security_path_* hooks added in this patch are similar to the
security_inode_* counterparts that already exist in the
sleepable_lsm_hooks list, and are called in roughly similar points and
contexts. Presumably, making them OK to be also annotated as
sleepable.

Building a kernel with DEBUG_ATOMIC_SLEEP options enabled and running
reasonable workloads stimulating activity that would be intercepted by
such security hooks didn't show any splats.

Notably, I haven't added all the security_path_* LSM hooks that are
available as I don't need them at this point in time.

Signed-off-by: Matt Bobrowski <mattbobrowski at google.com>
---
 kernel/bpf/bpf_lsm.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/kernel/bpf/bpf_lsm.c b/kernel/bpf/bpf_lsm.c
index 7d2f96413a57..63b4dc495125 100644
--- a/kernel/bpf/bpf_lsm.c
+++ b/kernel/bpf/bpf_lsm.c
@@ -304,6 +304,18 @@ BTF_ID(func, bpf_lsm_kernel_module_request)
 BTF_ID(func, bpf_lsm_kernel_read_file)
 BTF_ID(func, bpf_lsm_kernfs_init_security)
 
+#ifdef CONFIG_SECURITY_PATH
+BTF_ID(func, bpf_lsm_path_unlink)
+BTF_ID(func, bpf_lsm_path_mkdir)
+BTF_ID(func, bpf_lsm_path_rmdir)
+BTF_ID(func, bpf_lsm_path_truncate)
+BTF_ID(func, bpf_lsm_path_symlink)
+BTF_ID(func, bpf_lsm_path_link)
+BTF_ID(func, bpf_lsm_path_rename)
+BTF_ID(func, bpf_lsm_path_chmod)
+BTF_ID(func, bpf_lsm_path_chown)
+#endif /* CONFIG_SECURITY_PATH */
+
 #ifdef CONFIG_KEYS
 BTF_ID(func, bpf_lsm_key_free)
 #endif /* CONFIG_KEYS */
-- 
2.43.0.472.g3155946c3a-goog

/M