vfs: export check_sticky()
It's already duplicated in btrfs and about to be used in overlayfs too.
Move the sticky bit check to an inline helper and call the out-of-line
helper only in the unlikly case of the sticky bit being set.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 8d2b76e..4399f0c 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -765,23 +765,6 @@
return ret;
}
-/* copy of check_sticky in fs/namei.c()
-* It's inline, so penalty for filesystems that don't use sticky bit is
-* minimal.
-*/
-static inline int btrfs_check_sticky(struct inode *dir, struct inode *inode)
-{
- kuid_t fsuid = current_fsuid();
-
- if (!(dir->i_mode & S_ISVTX))
- return 0;
- if (uid_eq(inode->i_uid, fsuid))
- return 0;
- if (uid_eq(dir->i_uid, fsuid))
- return 0;
- return !capable(CAP_FOWNER);
-}
-
/* copy of may_delete in fs/namei.c()
* Check whether we can remove a link victim from directory dir, check
* whether the type of victim is right.
@@ -817,8 +800,7 @@
return error;
if (IS_APPEND(dir))
return -EPERM;
- if (btrfs_check_sticky(dir, victim->d_inode)||
- IS_APPEND(victim->d_inode)||
+ if (check_sticky(dir, victim->d_inode) || IS_APPEND(victim->d_inode) ||
IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode))
return -EPERM;
if (isdir) {
diff --git a/fs/namei.c b/fs/namei.c
index d944f6d..77fd536 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2384,22 +2384,17 @@
}
EXPORT_SYMBOL(kern_path_mountpoint);
-/*
- * It's inline, so penalty for filesystems that don't use sticky bit is
- * minimal.
- */
-static inline int check_sticky(struct inode *dir, struct inode *inode)
+int __check_sticky(struct inode *dir, struct inode *inode)
{
kuid_t fsuid = current_fsuid();
- if (!(dir->i_mode & S_ISVTX))
- return 0;
if (uid_eq(inode->i_uid, fsuid))
return 0;
if (uid_eq(dir->i_uid, fsuid))
return 0;
return !capable_wrt_inode_uidgid(inode, CAP_FOWNER);
}
+EXPORT_SYMBOL(__check_sticky);
/*
* Check whether we can remove a link victim from directory dir, check
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 5419df7..55cc0a3 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2259,6 +2259,7 @@
extern int inode_permission(struct inode *, int);
extern int __inode_permission(struct inode *, int);
extern int generic_permission(struct inode *, int);
+extern int __check_sticky(struct inode *dir, struct inode *inode);
static inline bool execute_ok(struct inode *inode)
{
@@ -2745,6 +2746,14 @@
return (mode & S_ISUID) || ((mode & S_ISGID) && (mode & S_IXGRP));
}
+static inline int check_sticky(struct inode *dir, struct inode *inode)
+{
+ if (!(dir->i_mode & S_ISVTX))
+ return 0;
+
+ return __check_sticky(dir, inode);
+}
+
static inline void inode_has_no_xattr(struct inode *inode)
{
if (!is_sxid(inode->i_mode) && (inode->i_sb->s_flags & MS_NOSEC))