Use path_walk_parent() to walk a path up to its parent.

No functional changes intended.

Signed-off-by: Song Liu <song@kernel.org>
---
 security/landlock/fs.c | 31 ++++++++++---------------------
 1 file changed, 10 insertions(+), 21 deletions(-)

diff --git a/security/landlock/fs.c b/security/landlock/fs.c
index 6fee7c20f64d..3adac544dc9e 100644
--- a/security/landlock/fs.c
+++ b/security/landlock/fs.c
@@ -837,8 +837,8 @@ static bool is_access_to_paths_allowed(
 	 * restriction.
 	 */
 	while (true) {
-		struct dentry *parent_dentry;
 		const struct landlock_rule *rule;
+		struct path root = {};
 
 		/*
 		 * If at least all accesses allowed on the destination are
@@ -895,34 +895,23 @@ static bool is_access_to_paths_allowed(
 		/* Stops when a rule from each layer grants access. */
 		if (allowed_parent1 && allowed_parent2)
 			break;
-jump_up:
-		if (walker_path.dentry == walker_path.mnt->mnt_root) {
-			if (follow_up(&walker_path)) {
-				/* Ignores hidden mount points. */
-				goto jump_up;
-			} else {
-				/*
-				 * Stops at the real root.  Denies access
-				 * because not all layers have granted access.
-				 */
-				break;
-			}
-		}
+
+		if (path_walk_parent(&walker_path, &root))
+			continue;
+
 		if (unlikely(IS_ROOT(walker_path.dentry))) {
 			/*
-			 * Stops at disconnected root directories.  Only allows
-			 * access to internal filesystems (e.g. nsfs, which is
-			 * reachable through /proc/<pid>/ns/<namespace>).
+			 * Stops at disconnected or real root directories.
+			 * Only allows access to internal filesystems
+			 * (e.g. nsfs, which is reachable through
+			 * /proc/<pid>/ns/<namespace>).
 			 */
 			if (walker_path.mnt->mnt_flags & MNT_INTERNAL) {
 				allowed_parent1 = true;
 				allowed_parent2 = true;
 			}
-			break;
 		}
-		parent_dentry = dget_parent(walker_path.dentry);
-		dput(walker_path.dentry);
-		walker_path.dentry = parent_dentry;
+		break;
 	}
 	path_put(&walker_path);
 
-- 
2.47.1

On 6/6/25 22:30, Song Liu wrote:
> Use path_walk_parent() to walk a path up to its parent.
> 
> No functional changes intended.
> 
> Signed-off-by: Song Liu <song@kernel.org>

There is also path walk code in collect_domain_accesses even though that
one doesn't walk pass mount points.  Not sure if that one should be
updated to use this helper as well, or maybe fine to keep using
dget_parent.