linux-kernel - [PATCH] vfs: reorder checks in may_create_in

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Date: Thu, 20 Jun 2024 14:03:59 +0200
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] vfs: reorder checks in may_create_in_sticky

The routine is called for all directories on file creation and weirdly
postpones the check if the dir is sticky to begin with. Instead it first
checks fifos and regular files (in that order), while avoidably pulling
globals.

No functional changes.

Signed-off-by: Mateusz Guzik <mjguzik@...il.com>
---
 fs/namei.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 63d1fb06da6b..b1600060ecfb 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1246,9 +1246,9 @@ static int may_create_in_sticky(struct mnt_idmap *idmap,
 	umode_t dir_mode = nd->dir_mode;
 	vfsuid_t dir_vfsuid = nd->dir_vfsuid;
 
-	if ((!sysctl_protected_fifos && S_ISFIFO(inode->i_mode)) ||
-	    (!sysctl_protected_regular && S_ISREG(inode->i_mode)) ||
-	    likely(!(dir_mode & S_ISVTX)) ||
+	if (likely(!(dir_mode & S_ISVTX)) ||
+	    (S_ISREG(inode->i_mode) && !sysctl_protected_regular) ||
+	    (S_ISFIFO(inode->i_mode) && !sysctl_protected_fifos) ||
 	    vfsuid_eq(i_uid_into_vfsuid(idmap, inode), dir_vfsuid) ||
 	    vfsuid_eq_kuid(i_uid_into_vfsuid(idmap, inode), current_fsuid()))
 		return 0;
-- 
2.43.0