linux-kernel - [PATCH] LANDLOCK: use kmem_cache for landlock

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Message-ID: <ZgSrBVidW1U6yP+h@ayush-HP-Pavilion-Gaming-Laptop-15-ec0xxx>
Date: Thu, 28 Mar 2024 04:55:57 +0530
From: Ayush Tiwari <ayushtiw0110@...il.com>
To: alison.schofield@...el.com, paul@...l-moore.com, mic@...ikod.net,
	fabio.maria.de.francesco@...ux.intel.com,
	linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org,
	gregkh@...uxfoundation.org
Cc: outreachy@...ts.linux.dev, linux-security-module@...r.kernel.org
Subject: [PATCH] LANDLOCK: use kmem_cache for landlock_object

Use kmem_cache replace kzalloc() calls with kmem_cache_zalloc() for
struct landlock_object and update the related dependencies.

Signed-off-by: Ayush Tiwari <ayushtiw0110@...il.com>
---
 security/landlock/fs.c     |  2 +-
 security/landlock/object.c | 14 ++++++++++++--
 security/landlock/object.h |  4 ++++
 security/landlock/setup.c  |  2 ++
 4 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/security/landlock/fs.c b/security/landlock/fs.c
index fc520a06f9af..227dd67dd902 100644
--- a/security/landlock/fs.c
+++ b/security/landlock/fs.c
@@ -124,7 +124,7 @@ static struct landlock_object *get_inode_object(struct inode *const inode)
 	if (unlikely(rcu_access_pointer(inode_sec->object))) {
 		/* Someone else just created the object, bail out and retry. */
 		spin_unlock(&inode->i_lock);
-		kfree(new_object);
+		kmem_cache_free(landlock_object_cache, new_object);
 
 		rcu_read_lock();
 		goto retry;
diff --git a/security/landlock/object.c b/security/landlock/object.c
index 1f50612f0185..df1354215617 100644
--- a/security/landlock/object.c
+++ b/security/landlock/object.c
@@ -17,6 +17,15 @@
 
 #include "object.h"
 
+struct kmem_cache *landlock_object_cache;
+
+void __init landlock_object_init(void)
+{
+	landlock_object_cache = kmem_cache_create(
+		"landlock_object_cache", sizeof(struct landlock_object), 0,
+		SLAB_PANIC, NULL);
+}
+
 struct landlock_object *
 landlock_create_object(const struct landlock_object_underops *const underops,
 		       void *const underobj)
@@ -25,7 +34,8 @@ landlock_create_object(const struct landlock_object_underops *const underops,
 
 	if (WARN_ON_ONCE(!underops || !underobj))
 		return ERR_PTR(-ENOENT);
-	new_object = kzalloc(sizeof(*new_object), GFP_KERNEL_ACCOUNT);
+	new_object =
+		kmem_cache_zalloc(landlock_object_cache, GFP_KERNEL_ACCOUNT);
 	if (!new_object)
 		return ERR_PTR(-ENOMEM);
 	refcount_set(&new_object->usage, 1);
@@ -62,6 +72,6 @@ void landlock_put_object(struct landlock_object *const object)
 		 * @object->underobj to @object (if it still exists).
 		 */
 		object->underops->release(object);
-		kfree_rcu(object, rcu_free);
+		kmem_cache_free(landlock_object_cache, object);
 	}
 }
diff --git a/security/landlock/object.h b/security/landlock/object.h
index 5f28c35e8aa8..8ba1af3ddc2e 100644
--- a/security/landlock/object.h
+++ b/security/landlock/object.h
@@ -13,6 +13,10 @@
 #include <linux/refcount.h>
 #include <linux/spinlock.h>
 
+extern struct kmem_cache *landlock_object_cache;
+
+void __init landlock_object_init(void);
+
 struct landlock_object;
 
 /**
diff --git a/security/landlock/setup.c b/security/landlock/setup.c
index f6dd33143b7f..a5fca4582ee1 100644
--- a/security/landlock/setup.c
+++ b/security/landlock/setup.c
@@ -16,6 +16,7 @@
 #include "net.h"
 #include "ptrace.h"
 #include "setup.h"
+#include "object.h"
 
 bool landlock_initialized __ro_after_init = false;
 
@@ -33,6 +34,7 @@ const struct lsm_id landlock_lsmid = {
 
 static int __init landlock_init(void)
 {
+	landlock_object_init();
 	landlock_add_cred_hooks();
 	landlock_add_ptrace_hooks();
 	landlock_add_fs_hooks();
-- 
2.40.1