[PATCH v5 03/24] landlock: Move domain hierarchy management

["Mickaël Salaün" <mic@digikod.net>]

Create a new domain.h file containing the struct landlock_hierarchy
definition and helpers.  This type will grow with audit support.  This
also prepares for a new domain type.

Cc: Günther Noack <gnoack@google.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Link: https://lore.kernel.org/r/20250131163059.1139617-4-mic@digikod.net
---

Changes since v4:
- Revert v3 changes because of the new audit rule patch removal.

Changes since v3:
- Export landlock_get_hierarchy() and landlock_put_hierarchy().
- Clean up Makefile entries.

Changes since v1:
- New patch.
---
 security/landlock/domain.h  | 48 +++++++++++++++++++++++++++++++++++++
 security/landlock/ruleset.c | 21 +++-------------
 security/landlock/ruleset.h | 17 +------------
 security/landlock/task.c    |  1 +
 4 files changed, 53 insertions(+), 34 deletions(-)
 create mode 100644 security/landlock/domain.h

diff --git a/security/landlock/domain.h b/security/landlock/domain.h
new file mode 100644
index 000000000000..015d61fd81ec
--- /dev/null
+++ b/security/landlock/domain.h
@@ -0,0 +1,48 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Landlock LSM - Domain management
+ *
+ * Copyright © 2016-2020 Mickaël Salaün <mic@digikod.net>
+ * Copyright © 2018-2020 ANSSI
+ */
+
+#ifndef _SECURITY_LANDLOCK_DOMAIN_H
+#define _SECURITY_LANDLOCK_DOMAIN_H
+
+#include <linux/mm.h>
+#include <linux/refcount.h>
+
+/**
+ * struct landlock_hierarchy - Node in a domain hierarchy
+ */
+struct landlock_hierarchy {
+	/**
+	 * @parent: Pointer to the parent node, or NULL if it is a root
+	 * Landlock domain.
+	 */
+	struct landlock_hierarchy *parent;
+	/**
+	 * @usage: Number of potential children domains plus their parent
+	 * domain.
+	 */
+	refcount_t usage;
+};
+
+static inline void
+landlock_get_hierarchy(struct landlock_hierarchy *const hierarchy)
+{
+	if (hierarchy)
+		refcount_inc(&hierarchy->usage);
+}
+
+static inline void landlock_put_hierarchy(struct landlock_hierarchy *hierarchy)
+{
+	while (hierarchy && refcount_dec_and_test(&hierarchy->usage)) {
+		const struct landlock_hierarchy *const freeme = hierarchy;
+
+		hierarchy = hierarchy->parent;
+		kfree(freeme);
+	}
+}
+
+#endif /* _SECURITY_LANDLOCK_DOMAIN_H */
diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
index 241ce44375b6..fb955354912d 100644
--- a/security/landlock/ruleset.c
+++ b/security/landlock/ruleset.c
@@ -23,6 +23,7 @@
 #include <linux/workqueue.h>
 
 #include "access.h"
+#include "domain.h"
 #include "limits.h"
 #include "object.h"
 #include "ruleset.h"
@@ -307,22 +308,6 @@ int landlock_insert_rule(struct landlock_ruleset *const ruleset,
 	return insert_rule(ruleset, id, &layers, ARRAY_SIZE(layers));
 }
 
-static void get_hierarchy(struct landlock_hierarchy *const hierarchy)
-{
-	if (hierarchy)
-		refcount_inc(&hierarchy->usage);
-}
-
-static void put_hierarchy(struct landlock_hierarchy *hierarchy)
-{
-	while (hierarchy && refcount_dec_and_test(&hierarchy->usage)) {
-		const struct landlock_hierarchy *const freeme = hierarchy;
-
-		hierarchy = hierarchy->parent;
-		kfree(freeme);
-	}
-}
-
 static int merge_tree(struct landlock_ruleset *const dst,
 		      struct landlock_ruleset *const src,
 		      const enum landlock_key_type key_type)
@@ -477,7 +462,7 @@ static int inherit_ruleset(struct landlock_ruleset *const parent,
 		err = -EINVAL;
 		goto out_unlock;
 	}
-	get_hierarchy(parent->hierarchy);
+	landlock_get_hierarchy(parent->hierarchy);
 	child->hierarchy->parent = parent->hierarchy;
 
 out_unlock:
@@ -501,7 +486,7 @@ static void free_ruleset(struct landlock_ruleset *const ruleset)
 		free_rule(freeme, LANDLOCK_KEY_NET_PORT);
 #endif /* IS_ENABLED(CONFIG_INET) */
 
-	put_hierarchy(ruleset->hierarchy);
+	landlock_put_hierarchy(ruleset->hierarchy);
 	kfree(ruleset);
 }
 
diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h
index 52f4f0af6ab0..bbb5996545d2 100644
--- a/security/landlock/ruleset.h
+++ b/security/landlock/ruleset.h
@@ -17,6 +17,7 @@
 #include <linux/workqueue.h>
 
 #include "access.h"
+#include "domain.h"
 #include "limits.h"
 #include "object.h"
 
@@ -108,22 +109,6 @@ struct landlock_rule {
 	struct landlock_layer layers[] __counted_by(num_layers);
 };
 
-/**
- * struct landlock_hierarchy - Node in a ruleset hierarchy
- */
-struct landlock_hierarchy {
-	/**
-	 * @parent: Pointer to the parent node, or NULL if it is a root
-	 * Landlock domain.
-	 */
-	struct landlock_hierarchy *parent;
-	/**
-	 * @usage: Number of potential children domains plus their parent
-	 * domain.
-	 */
-	refcount_t usage;
-};
-
 /**
  * struct landlock_ruleset - Landlock ruleset
  *
diff --git a/security/landlock/task.c b/security/landlock/task.c
index dc7dab78392e..98894ad1abc7 100644
--- a/security/landlock/task.c
+++ b/security/landlock/task.c
@@ -18,6 +18,7 @@
 
 #include "common.h"
 #include "cred.h"
+#include "domain.h"
 #include "fs.h"
 #include "ruleset.h"
 #include "setup.h"
-- 
2.48.1