linux/fs/sysfs/mount.c
Li Zefan fed95bab8d sysfs: fix namespace refcnt leak
As mount() and kill_sb() is not a one-to-one match, we shoudn't get
ns refcnt unconditionally in sysfs_mount(), and instead we should
get the refcnt only when kernfs_mount() allocated a new superblock.

v2:
- Changed the name of the new argument, suggested by Tejun.
- Made the argument optional, suggested by Tejun.

v3:
- Make the new argument as second-to-last arg, suggested by Tejun.

Signed-off-by: Li Zefan <lizefan@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
 ---
 fs/kernfs/mount.c      | 8 +++++++-
 fs/sysfs/mount.c       | 5 +++--
 include/linux/kernfs.h | 9 +++++----
 3 files changed, 15 insertions(+), 7 deletions(-)
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-25 07:37:52 -08:00

80 lines
1.7 KiB
C

/*
* fs/sysfs/symlink.c - operations for initializing and mounting sysfs
*
* Copyright (c) 2001-3 Patrick Mochel
* Copyright (c) 2007 SUSE Linux Products GmbH
* Copyright (c) 2007 Tejun Heo <teheo@suse.de>
*
* This file is released under the GPLv2.
*
* Please see Documentation/filesystems/sysfs.txt for more information.
*/
#define DEBUG
#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/init.h>
#include <linux/user_namespace.h>
#include "sysfs.h"
static struct kernfs_root *sysfs_root;
struct kernfs_node *sysfs_root_kn;
static struct dentry *sysfs_mount(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data)
{
struct dentry *root;
void *ns;
bool new_sb;
if (!(flags & MS_KERNMOUNT)) {
if (!capable(CAP_SYS_ADMIN) && !fs_fully_visible(fs_type))
return ERR_PTR(-EPERM);
if (!kobj_ns_current_may_mount(KOBJ_NS_TYPE_NET))
return ERR_PTR(-EPERM);
}
ns = kobj_ns_grab_current(KOBJ_NS_TYPE_NET);
root = kernfs_mount_ns(fs_type, flags, sysfs_root, &new_sb, ns);
if (IS_ERR(root) || !new_sb)
kobj_ns_drop(KOBJ_NS_TYPE_NET, ns);
return root;
}
static void sysfs_kill_sb(struct super_block *sb)
{
void *ns = (void *)kernfs_super_ns(sb);
kernfs_kill_sb(sb);
kobj_ns_drop(KOBJ_NS_TYPE_NET, ns);
}
static struct file_system_type sysfs_fs_type = {
.name = "sysfs",
.mount = sysfs_mount,
.kill_sb = sysfs_kill_sb,
.fs_flags = FS_USERNS_MOUNT,
};
int __init sysfs_init(void)
{
int err;
sysfs_root = kernfs_create_root(NULL, NULL);
if (IS_ERR(sysfs_root))
return PTR_ERR(sysfs_root);
sysfs_root_kn = sysfs_root->kn;
err = register_filesystem(&sysfs_fs_type);
if (err) {
kernfs_destroy_root(sysfs_root);
return err;
}
return 0;
}