linux-kernel - [PATCH] fs: dedup handling of struct filename init and refcounts bumps

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250313142744.1323281-1-mjguzik@gmail.com>
Date: Thu, 13 Mar 2025 15:27:44 +0100
From: Mateusz Guzik <mjguzik@...il.com>
To: brauner@...nel.org
Cc: viro@...iv.linux.org.uk,
	jack@...e.cz,
	linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org,
	Mateusz Guzik <mjguzik@...il.com>
Subject: [PATCH] fs: dedup handling of struct filename init and refcounts bumps

No functional changes.

Signed-off-by: Mateusz Guzik <mjguzik@...il.com>
---

This is extracted from the patch which tried to introduce optional
non-atomic operation.

I think this is an ok cleanup, but I'm not going to argue about it.

ultimately this is a big NOP

 fs/namei.c         | 17 +++++++++--------
 include/linux/fs.h |  6 ++++++
 kernel/auditsc.c   | 12 +++++-------
 3 files changed, 20 insertions(+), 15 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 06765d320e7e..699158c325bf 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -125,6 +125,13 @@
 
 #define EMBEDDED_NAME_MAX	(PATH_MAX - offsetof(struct filename, iname))
 
+static inline void initname(struct filename *name)
+{
+	name->uptr = NULL;
+	name->aname = NULL;
+	atomic_set(&name->refcnt, 1);
+}
+
 struct filename *
 getname_flags(const char __user *filename, int flags)
 {
@@ -203,10 +210,7 @@ getname_flags(const char __user *filename, int flags)
 			return ERR_PTR(-ENAMETOOLONG);
 		}
 	}
-
-	atomic_set(&result->refcnt, 1);
-	result->uptr = filename;
-	result->aname = NULL;
+	initname(result);
 	audit_getname(result);
 	return result;
 }
@@ -264,11 +268,8 @@ struct filename *getname_kernel(const char * filename)
 		return ERR_PTR(-ENAMETOOLONG);
 	}
 	memcpy((char *)result->name, filename, len);
-	result->uptr = NULL;
-	result->aname = NULL;
-	atomic_set(&result->refcnt, 1);
+	initname(result);
 	audit_getname(result);
-
 	return result;
 }
 EXPORT_SYMBOL(getname_kernel);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 62440a9383dc..016b0fe1536e 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2865,6 +2865,12 @@ static inline struct filename *getname_maybe_null(const char __user *name, int f
 extern void putname(struct filename *name);
 DEFINE_FREE(putname, struct filename *, if (!IS_ERR_OR_NULL(_T)) putname(_T))
 
+static inline struct filename *refname(struct filename *name)
+{
+	atomic_inc(&name->refcnt);
+	return name;
+}
+
 extern int finish_open(struct file *file, struct dentry *dentry,
 			int (*open)(struct inode *, struct file *));
 extern int finish_no_open(struct file *file, struct dentry *dentry);
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 9c853cde9abe..78fd876a5473 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -2207,10 +2207,8 @@ __audit_reusename(const __user char *uptr)
 	list_for_each_entry(n, &context->names_list, list) {
 		if (!n->name)
 			continue;
-		if (n->name->uptr == uptr) {
-			atomic_inc(&n->name->refcnt);
-			return n->name;
-		}
+		if (n->name->uptr == uptr)
+			return refname(n->name);
 	}
 	return NULL;
 }
@@ -2237,7 +2235,7 @@ void __audit_getname(struct filename *name)
 	n->name = name;
 	n->name_len = AUDIT_NAME_FULL;
 	name->aname = n;
-	atomic_inc(&name->refcnt);
+	refname(name);
 }
 
 static inline int audit_copy_fcaps(struct audit_names *name,
@@ -2369,7 +2367,7 @@ void __audit_inode(struct filename *name, const struct dentry *dentry,
 		return;
 	if (name) {
 		n->name = name;
-		atomic_inc(&name->refcnt);
+		refname(name);
 	}
 
 out:
@@ -2496,7 +2494,7 @@ void __audit_inode_child(struct inode *parent,
 		if (found_parent) {
 			found_child->name = found_parent->name;
 			found_child->name_len = AUDIT_NAME_FULL;
-			atomic_inc(&found_child->name->refcnt);
+			refname(found_child->name);
 		}
 	}
 
-- 
2.43.0