[RFC PATCH bpf-next 04/12] bpf: mark struct path trusted

[Justin Suess <utilityemal77@gmail.com>]

Walking a trusted struct path yields a trusted dentry - a live path
never carries a NULL dentry - so BPF programs can use it with kfuncs
that require trusted arguments.

Signed-off-by: Song Liu <song@kernel.org>
[justin: carried only the verifier.c hunk of the original patch,
 trusted instead of trusted-or-null]
Signed-off-by: Justin Suess <utilityemal77@gmail.com>
---
 kernel/bpf/verifier.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index fd3c0206bd67..24ec4b037de7 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -6300,6 +6300,10 @@ BTF_TYPE_SAFE_TRUSTED(struct scx_sub_detach_args) {
 	struct sched_ext_ops *ops;
 };
 
+BTF_TYPE_SAFE_TRUSTED(struct path) {
+	struct dentry *dentry;
+};
+
 BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct dentry) {
 	struct inode *d_inode;
 };
@@ -6352,6 +6356,7 @@ static bool type_is_trusted(struct bpf_verifier_env *env,
 	BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct scx_cpu_release_args));
 	BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct scx_sub_attach_args));
 	BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct scx_sub_detach_args));
+	BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct path));
 
 	return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id, "__safe_trusted");
 }
-- 
2.55.0